Science.gov

Sample records for accelerated time frame

  1. Independent Study Unit on Accelerated Reference Frames

    ERIC Educational Resources Information Center

    Poultney, S. K.

    1973-01-01

    Presents a list of topics, research areas, references, and laboratory equipment which is prepared to facilitate general-science students' understanding of physics aspects in accelerated reference frames after their study of circular motion and Galilean relativity in mechanics. (CC)

  2. Modeling laser-plasma acceleration in the laboratory frame

    SciTech Connect

    2011-01-01

    A simulation of laser-plasma acceleration in the laboratory frame. Both the laser and the wakefield buckets must be resolved over the entire domain of the plasma, requiring many cells and many time steps. While researchers often use a simulation window that moves with the pulse, this reduces only the multitude of cells, not the multitude of time steps. For an artistic impression of how to solve the simulation by using the boosted-frame method, watch the video "Modeling laser-plasma acceleration in the wakefield frame."

  3. 2-20 ns interframe time 2-frame 6.151 keV x-ray imaging on the recently upgraded Z Accelerator: A progress report

    SciTech Connect

    Bennett, G. R.; Smith, I. C.; Shores, J. E.; Sinars, D. B.; Robertson, G.; Atherton, B. W.; Jones, M. C.; Porter, J. L.

    2008-10-15

    When used for the production of an x-ray imaging backlighter source on Sandia National Laboratories' recently upgraded 26 MA Z Accelerator, the terawatt-class, multikilojoule, 526.57 nm Z-Beamlet laser (ZBL) [P. K. Rambo et al., Appl. Opt. 44, 2421 (2005)], in conjunction with the 6.151 keV (1s{sup 2}-1s2p triplet line of He-like Mn) curved-crystal imager [D. B. Sinars et al., Rev. Sci. Instrum. 75, 3672 (2004); G. R. Bennett et al., Rev. Sci. Instrum. 77, 10E322 (2006)], is capable of providing a high quality x radiograph per Z shot for inertial confinement fusion (ICF), complex hydrodynamics, and other high-energy-density physics experiments. For example, this diagnostic has recently afforded microgram-scale mass perturbation measurements on an imploding ignition-scale 1 mg ICF capsule [G. R. Bennett et al., Phys. Rev. Lett. 99, 205003 (2007)], where the perturbation was initiated by a surrogate deuterium-tritium (DT) fuel fill tube. Using an angle-time multiplexing technique, ZBL now has the capability to provide two spatially and temporally separated foci in the Z chamber, allowing 'two-frame' imaging to be performed, with an interframe time range of 2-20 ns. This multiplexing technique allows the full area of the four-pass amplifiers to be used for the two pulses, rather than split the amplifiers effectively into two rectangular sections, with one leg delayed with respect to the other, which would otherwise double the power imposed onto the various optics thereby halving the damage threshold, for the same irradiance on target. The 6.151 keV two frame technique has recently been used to image imploding wire arrays, using a 7.3 ns interframe time. The diagnostic will soon be converted to operate with p-rather than s-polarized laser light for enhanced laser absorption in the Mn foil, plus other changes (e.g., operation at the possibly brighter 6.181 keV Mn 1s{sup 2}-1s2p singlet line), to increase x-ray yields. Also, a highly sensitive inline multiframe ultrafast

  4. 2-20 ns interframe time 2-frame 6.151 keV x-ray imaging on the recently upgraded Z Accelerator: A progress report

    NASA Astrophysics Data System (ADS)

    Bennett, G. R.; Smith, I. C.; Shores, J. E.; Sinars, D. B.; Robertson, G.; Atherton, B. W.; Jones, M. C.; Porter, J. L.

    2008-10-01

    When used for the production of an x-ray imaging backlighter source on Sandia National Laboratories' recently upgraded 26MA Z Accelerator, the terawatt-class, multikilojoule, 526.57nm Z-Beamlet laser (ZBL) [P. K. Rambo et al., Appl. Opt. 44, 2421 (2005)], in conjunction with the 6.151keV (1s2-1s2p triplet line of He-like Mn) curved-crystal imager [D. B. Sinars et al., Rev. Sci. Instrum. 75, 3672 (2004); G. R. Bennett et al., Rev. Sci. Instrum. 77, 10E322 (2006)], is capable of providing a high quality x radiograph per Z shot for inertial confinement fusion (ICF), complex hydrodynamics, and other high-energy-density physics experiments. For example, this diagnostic has recently afforded microgram-scale mass perturbation measurements on an imploding ignition-scale 1mg ICF capsule [G. R. Bennett et al., Phys. Rev. Lett. 99, 205003 (2007)], where the perturbation was initiated by a surrogate deuterium-tritium (DT) fuel fill tube. Using an angle-time multiplexing technique, ZBL now has the capability to provide two spatially and temporally separated foci in the Z chamber, allowing "two-frame" imaging to be performed, with an interframe time range of 2-20ns. This multiplexing technique allows the full area of the four-pass amplifiers to be used for the two pulses, rather than split the amplifiers effectively into two rectangular sections, with one leg delayed with respect to the other, which would otherwise double the power imposed onto the various optics thereby halving the damage threshold, for the same irradiance on target. The 6.151keV two frame technique has recently been used to image imploding wire arrays, using a 7.3ns interframe time. The diagnostic will soon be converted to operate with p-rather than s-polarized laser light for enhanced laser absorption in the Mn foil, plus other changes (e.g., operation at the possibly brighter 6.181keV Mn 1s2-1s2p singlet line), to increase x-ray yields. Also, a highly sensitive inline multiframe ultrafast (1ns gate time

  5. Solid-state framing camera with multiple time frames

    SciTech Connect

    Baker, K. L.; Stewart, R. E.; Steele, P. T.; Vernon, S. P.; Hsing, W. W.; Remington, B. A.

    2013-10-07

    A high speed solid-state framing camera has been developed which can operate over a wide range of photon energies. This camera measures the two-dimensional spatial profile of the flux incident on a cadmium selenide semiconductor at multiple times. This multi-frame camera has been tested at 3.1 eV and 4.5 keV. The framing camera currently records two frames with a temporal separation between the frames of 5 ps but this separation can be varied between hundreds of femtoseconds up to nanoseconds and the number of frames can be increased by angularly multiplexing the probe beam onto the cadmium selenide semiconductor.

  6. Modeling laser wakefield accelerators in a Lorentz boosted frame

    SciTech Connect

    Vay, J.-L.; Geddes, C.G.R.; Cormier-Michel, E.; Grotec, D. P.

    2010-06-15

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high-frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing the frame of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.

  7. Modeling laser wakefield accelerators in a Lorentz boosted frame

    SciTech Connect

    Vay, J.-L.; Geddes, C.G.R.; Cormier-Michel, E.; Grote, D.P.

    2010-09-15

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [1] is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing theframe of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.

  8. Tripartite entanglement of fermionic system in accelerated frames

    SciTech Connect

    Khan, Salman

    2014-09-15

    The dynamics of tripartite entanglement of fermionic system in noninertial frames through linear contraction criterion when one or two observers are accelerated is investigated. In one observer accelerated case the entanglement measurement is not invariant with respect to the partial realignment of different subsystems and for two observers accelerated case it is invariant. It is shown that the acceleration of the frame does not generate entanglement in any bipartite subsystems. Unlike the bipartite states, the genuine tripartite entanglement does not completely vanish in both one observer accelerated and two observers accelerated cases even in the limit of infinite acceleration. The degradation of tripartite entanglement is fast when two observers are accelerated than when one observer is accelerated. It is shown that tripartite entanglement is a better resource for quantum information processing than the bipartite entanglement in noninertial frames. - Highlights: • Tripartite entanglement of fermionic system in noninertial frames is studied. • Linear contraction criterion for quantifying tripartite entanglement is used. • Acceleration does not produce any bipartite entanglement. • The invariance of entanglement quantifier depends on accelerated observers. • The tripartite entanglement degrades against the acceleration, it never vanishes.

  9. 10 CFR 710.35 - Time frames.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Time frames. 710.35 Section 710.35 Energy DEPARTMENT OF... Matter or Special Nuclear Material Miscellaneous § 710.35 Time frames. Statements of time established for processing aspects of a case under this subpart are the agency's desired time frames in implementing...

  10. 10 CFR 710.35 - Time frames.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Time frames. 710.35 Section 710.35 Energy DEPARTMENT OF... Matter or Special Nuclear Material Miscellaneous § 710.35 Time frames. Statements of time established for processing aspects of a case under this subpart are the agency's desired time frames in implementing...

  11. 10 CFR 710.35 - Time frames.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Time frames. 710.35 Section 710.35 Energy DEPARTMENT OF... Matter or Special Nuclear Material Miscellaneous § 710.35 Time frames. Statements of time established for processing aspects of a case under this subpart are the agency's desired time frames in implementing...

  12. GPU accelerated processing of astronomical high frame-rate videosequences

    NASA Astrophysics Data System (ADS)

    Vítek, Stanislav; Švihlík, Jan; Krasula, Lukáš; Fliegel, Karel; Páta, Petr

    2015-09-01

    Astronomical instruments located around the world are producing an incredibly large amount of possibly interesting scientific data. Astronomical research is expanding into large and highly sensitive telescopes. Total volume of data rates per night of operations also increases with the quality and resolution of state-of-the-art CCD/CMOS detectors. Since many of the ground-based astronomical experiments are placed in remote locations with limited access to the Internet, it is necessary to solve the problem of the data storage. It mostly means that current data acquistion, processing and analyses algorithm require review. Decision about importance of the data has to be taken in very short time. This work deals with GPU accelerated processing of high frame-rate astronomical video-sequences, mostly originating from experiment MAIA (Meteor Automatic Imager and Analyser), an instrument primarily focused to observing of faint meteoric events with a high time resolution. The instrument with price bellow 2000 euro consists of image intensifier and gigabite ethernet camera running at 61 fps. With resolution better than VGA the system produces up to 2TB of scientifically valuable video data per night. Main goal of the paper is not to optimize any GPU algorithm, but to propose and evaluate parallel GPU algorithms able to process huge amount of video-sequences in order to delete all uninteresting data.

  13. Time evolution of an SLR reference frame

    NASA Astrophysics Data System (ADS)

    Angermann, D.; Gerstl, M.; Kelm, R.; Müller, H.; Seemüller, W.; Vei, M.

    2002-07-01

    On the basis of LAGEOS-1 and LAGEOS-2 data we computed a 10-years (1990-2000) solution for SLR station positions and velocities. The paper describes the data processing with the DGFI software package DOGS. We present results for station coordinates and their time variation for 41 stations of the global SLR network, and discuss the stability and time evolution of the SLR reference frame established in the same way. We applied different methods to assess the quality and consistency of the SLR results. The results presented in this paper include: (1) a time series of weekly estimated station coordinates; (2) a comparison of a 10-year LAGEOS-1 and LAGEOS-2 solution; (3) a comparison of 2.5-year solutions with the combined 10-year solution to assess the internal stability and the time evolution of the SLR reference frame; (4) a comparison of the SLR reference frame with ITRF97; and (5) a comparison of SLR station velocities with those of ITRF97 and NNR NUVEL-1A.

  14. Accelerated high-frame-rate mouse heart cine-MRI using compressed sensing reconstruction.

    PubMed

    Motaal, Abdallah G; Coolen, Bram F; Abdurrachim, Desiree; Castro, Rui M; Prompers, Jeanine J; Florack, Luc M J; Nicolay, Klaas; Strijkers, Gustav J

    2013-04-01

    We introduce a new protocol to obtain very high-frame-rate cinematographic (Cine) MRI movies of the beating mouse heart within a reasonable measurement time. The method is based on a self-gated accelerated fast low-angle shot (FLASH) acquisition and compressed sensing reconstruction. Key to our approach is that we exploit the stochastic nature of the retrospective triggering acquisition scheme to produce an undersampled and random k-t space filling that allows for compressed sensing reconstruction and acceleration. As a standard, a self-gated FLASH sequence with a total acquisition time of 10 min was used to produce single-slice Cine movies of seven mouse hearts with 90 frames per cardiac cycle. Two times (2×) and three times (3×) k-t space undersampled Cine movies were produced from 2.5- and 1.5-min data acquisitions, respectively. The accelerated 90-frame Cine movies of mouse hearts were successfully reconstructed with a compressed sensing algorithm. The movies had high image quality and the undersampling artifacts were effectively removed. Left ventricular functional parameters, i.e. end-systolic and end-diastolic lumen surface areas and early-to-late filling rate ratio as a parameter to evaluate diastolic function, derived from the standard and accelerated Cine movies, were nearly identical.

  15. Time reversibility in the quantum frame

    SciTech Connect

    Masot-Conde, Fátima

    2014-12-04

    Classic Mechanics and Electromagnetism, conventionally taken as time-reversible, share the same concept of motion (either of mass or charge) as the basis of the time reversibility in their own fields. This paper focuses on the relationship between mobile geometry and motion reversibility. The goal is to extrapolate the conclusions to the quantum frame, where matter and radiation behave just as elementary mobiles. The possibility that the asymmetry of Time (Time’s arrow) is an effect of a fundamental quantum asymmetry of elementary particles, turns out to be a consequence of the discussion.

  16. 28 CFR 570.21 - Time-frames.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Time-frames. 570.21 Section 570.21... PROGRAMS Pre-Release Community Confinement § 570.21 Time-frames. (a) Community confinement. Inmates may be... inmate's term of imprisonment or six months. (c) Exceeding time-frames. These time-frames may be...

  17. 28 CFR 570.21 - Time-frames.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Time-frames. 570.21 Section 570.21... PROGRAMS Pre-Release Community Confinement § 570.21 Time-frames. (a) Community confinement. Inmates may be... inmate's term of imprisonment or six months. (c) Exceeding time-frames. These time-frames may be...

  18. 28 CFR 570.21 - Time-frames.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Time-frames. 570.21 Section 570.21... PROGRAMS Pre-Release Community Confinement § 570.21 Time-frames. (a) Community confinement. Inmates may be... inmate's term of imprisonment or six months. (c) Exceeding time-frames. These time-frames may be...

  19. 28 CFR 570.21 - Time-frames.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Time-frames. 570.21 Section 570.21... PROGRAMS Pre-Release Community Confinement § 570.21 Time-frames. (a) Community confinement. Inmates may be... inmate's term of imprisonment or six months. (c) Exceeding time-frames. These time-frames may be...

  20. Effects of Hyperbolic Rotation in Minkowski Space on the Modeling of Plasma Accelerators in a Lorentz Boosted Frame

    SciTech Connect

    Vay, J.-L.; Geddes, C. G. R.; Cormier-Michel, E.; Grote, D. P.

    2010-09-21

    Laser driven plasma accelerators promise much shorter particle accelerators but their development requires detailed simulations that challenge or exceed current capabilities. We report the first direct simulations of stages up to 1 TeV from simulations using a Lorentz boosted calculation frame resulting in a million times speedup, thanks to a frame boost as high as gamma = 1300. Effects of the hyperbolic rotation in Minkowski space resulting from the frame boost on the laser propagation in the plasma is shown to be key in the mitigation of a numerical instability that was limiting previous attempts.

  1. The effects of the framing of time on delay discounting.

    PubMed

    DeHart, William Brady; Odum, Amy L

    2015-01-01

    We examined the effects of the framing of time on delay discounting. Delay discounting is the process by which delayed outcomes are devalued as a function of time. Time in a titrating delay discounting task is often framed in calendar units (e.g., as 1 week, 1 month, etc.). When time is framed as a specific date, delayed outcomes are discounted less compared to the calendar format. Other forms of framing time; however, have not been explored. All participants completed a titrating calendar unit delay-discounting task for money. Participants were also assigned to one of two delay discounting tasks: time as dates (e.g., June 1st, 2015) or time in units of days (e.g., 5000 days), using the same delay distribution as the calendar delay-discounting task. Time framed as dates resulted in less discounting compared to the calendar method, whereas time framed as days resulted in greater discounting compared to the calendar method. The hyperboloid model fit best compared to the hyperbola and exponential models. How time is framed may alter how participants attend to the delays as well as how the delayed outcome is valued. Altering how time is framed may serve to improve adherence to goals with delayed outcomes.

  2. Quantum mechanics in noninertial reference frames: Relativistic accelerations and fictitious forces

    NASA Astrophysics Data System (ADS)

    Klink, W. H.; Wickramasekara, S.

    2016-06-01

    One-particle systems in relativistically accelerating reference frames can be associated with a class of unitary representations of the group of arbitrary coordinate transformations, an extension of the Wigner-Bargmann definition of particles as the physical realization of unitary irreducible representations of the Poincaré group. Representations of the group of arbitrary coordinate transformations become necessary to define unitary operators implementing relativistic acceleration transformations in quantum theory because, unlike in the Galilean case, the relativistic acceleration transformations do not themselves form a group. The momentum operators that follow from these representations show how the fictitious forces in noninertial reference frames are generated in quantum theory.

  3. SHORT ACCELERATION TIMES FROM SUPERDIFFUSIVE SHOCK ACCELERATION IN THE HELIOSPHERE

    SciTech Connect

    Perri, S.; Zimbardo, G.

    2015-12-10

    The analysis of time profiles of particles accelerated at interplanetary shocks allows particle transport properties to be inferred. The frequently observed power-law decay upstream, indeed, implies a superdiffusive particle transport when the level of magnetic field variance does not change as the time interval from the shock front increases. In this context, a superdiffusive shock acceleration (SSA) theory has been developed, allowing us to make predictions of the acceleration times. In this work we estimate for a number of interplanetary shocks, including the solar wind termination shock, the acceleration times for energetic protons in the framework of SSA and we compare the results with the acceleration times predicted by standard diffusive shock acceleration. The acceleration times due to SSA are found to be much shorter than in the classical model, and also shorter than the interplanetary shock lifetimes. This decrease of the acceleration times is due to the scale-free nature of the particle displacements in the framework of superdiffusion. Indeed, very long displacements are possible, increasing the probability for particles far from the front of the shock to return, and short displacements have a high probability of occurrence, increasing the chances for particles close to the front to cross the shock many times.

  4. Superdiffusive shock acceleration and short acceleration times at interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Perri, Silvia; Zimbardo, Gaetano

    2016-04-01

    The analysis of time profiles of particles accelerated at interplanetary shock waves has shown evidence for superdiffusive transport in the upstream region. Superdiffusive transport is characterized by a mean square displacement that grows faster than linearly in time and by non Gaussian statistics for the distribution of the particle jump lengths. In the superdiffusive framework it has been shown that particle time profiles upstream of a planar shock decay as power laws, at variance with exponential particle time profiles predicted in the case of diffusive transport. A large number of interplanetary shocks, including coronal mass ejection driven shocks, exhibit energetic particle time profiles that decay as power laws far upstream. In order to take this evidence into account, we have extended the standard theory of diffusive shock acceleration to the case of particle superdiffusive transport (superdiffusive shock acceleration). This has allowed us to derive both hard energy spectral indices and short acceleration times. This new theory has been tested for a number of interplanetary shock waves, observed by the Ulysses and the ACE spacecraft, and for the termination shock. The superdiffusive shock acceleration leads to a strong reduction of the acceleration times (even of about one order of magnitude) with respect to the diffusive shock acceleration. Thus, this new framework provides a substantial advancement in the understanding of the processes of particle acceleration and particle transport, which are among the main objectives of the new Solar Probe and Solar Orbiter space missions.

  5. Time and Outcome Framing in Intertemporal Tradeoffs

    ERIC Educational Resources Information Center

    Scholten, Marc; Read, Daniel

    2013-01-01

    A robust anomaly in intertemporal choice is the delay-speedup asymmetry: Receipts are discounted more, and payments are discounted less, when delayed than when expedited over the same interval. We developed 2 versions of the tradeoff model (Scholten & Read, 2010) to address such situations, in which an outcome is expected at a given time but…

  6. Synchronization of high speed framing camera and intense electron-beam accelerator.

    PubMed

    Cheng, Xin-Bing; Liu, Jin-Liang; Hong, Zhi-Qiang; Qian, Bao-Liang

    2012-06-01

    A new trigger program is proposed to realize the synchronization of high speed framing camera (HSFC) and intense electron-beam accelerator (IEBA). The trigger program which include light signal acquisition radiated from main switch of IEBA and signal processing circuit could provide a trigger signal with rise time of 17 ns and amplitude of about 5 V. First, the light signal was collected by an avalanche photodiode (APD) module, and the delay time between the output voltage of APD and load voltage of IEBA was tested, it was about 35 ns. Subsequently, the output voltage of APD was processed further by the signal processing circuit to obtain the trigger signal. At last, by combining the trigger program with an IEBA, the trigger program operated stably, and a delay time of 30 ns between the trigger signal of HSFC and output voltage of IEBA was obtained. Meanwhile, when surface flashover occurred at the high density polyethylene sample, the delay time between the trigger signal of HSFC and flashover current was up to 150 ns, which satisfied the need of synchronization of HSFC and IEBA. So the experiment results proved that the trigger program could compensate the time (called compensated time) of the trigger signal processing time and the inherent delay time of the HSFC. PMID:22755659

  7. Reducing video frame rate increases remote optimal focus time

    NASA Technical Reports Server (NTRS)

    Haines, Richard F.

    1993-01-01

    Twelve observers made best optical focus adjustments to a microscope whose high-resolution pattern was video monitored and displayed first on a National Television System Committee (NTSC) analog color monitor and second on a digitally compressed computer monitor screen at frame rates ranging (in six steps) from 1.5 to 30 frames per second (fps). This was done to determine whether reducing the frame rate affects the image focus. Reducing frame rate has been shown to be an effective and acceptable means of reducing transmission bandwidth of dynamic video imagery sent from Space Station Freedom (SSF) to ground scientists. Three responses were recorded per trial: time to complete the focus adjustment, number of changes of focus direction, and subjective rating of final image quality. It was found that: the average time to complete the focus setting increases from 4.5 sec at 30 fps to 7.9 sec at 1.5 fps (statistical probability = 1.2 x 10(exp -7)); there is no significant difference in the number of changes in the direction of focus adjustment across these frame rates; and there is no significant change in subjectively determined final image quality across these frame rates. These data can be used to help pre-plan future remote optical-focus operations on SSF.

  8. Enabling Lorentz boosted frame particle-in-cell simulations of laser wakefield acceleration in quasi-3D geometry

    NASA Astrophysics Data System (ADS)

    Yu, Peicheng; Xu, Xinlu; Davidson, Asher; Tableman, Adam; Dalichaouch, Thamine; Li, Fei; Meyers, Michael D.; An, Weiming; Tsung, Frank S.; Decyk, Viktor K.; Fiuza, Frederico; Vieira, Jorge; Fonseca, Ricardo A.; Lu, Wei; Silva, Luis O.; Mori, Warren B.

    2016-07-01

    When modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) algorithm in a Lorentz boosted frame, the plasma is drifting relativistically at βb c towards the laser, which can lead to a computational speedup of ∼ γb2 = (1 - βb2)-1. Meanwhile, when LWFA is modeled in the quasi-3D geometry in which the electromagnetic fields and current are decomposed into a limited number of azimuthal harmonics, speedups are achieved by modeling three dimensional (3D) problems with the computational loads on the order of two dimensional r - z simulations. Here, we describe a method to combine the speedups from the Lorentz boosted frame and quasi-3D algorithms. The key to the combination is the use of a hybrid Yee-FFT solver in the quasi-3D geometry that significantly mitigates the Numerical Cerenkov Instability (NCI) which inevitably arises in a Lorentz boosted frame due to the unphysical coupling of Langmuir modes and EM modes of the relativistically drifting plasma in these simulations. In addition, based on the space-time distribution of the LWFA data in the lab and boosted frame, we propose to use a moving window to follow the drifting plasma, instead of following the laser driver as is done in the LWFA lab frame simulations, in order to further reduce the computational loads. We describe the details of how the NCI is mitigated for the quasi-3D geometry, the setups for simulations which combine the Lorentz boosted frame, quasi-3D geometry, and the use of a moving window, and compare the results from these simulations against their corresponding lab frame cases. Good agreement is obtained among these sample simulations, particularly when there is no self-trapping, which demonstrates it is possible to combine the Lorentz boosted frame and the quasi-3D algorithms when modeling LWFA. We also discuss the preliminary speedups achieved in these sample simulations.

  9. Numerical methods for instability mitigation in the modeling of laser wakefield accelerators in a Lorentz-boosted frame

    SciTech Connect

    Vay, J.-L.; Geddes, C.G.R.; Cormier-Michel, E.; Grote, D.P.

    2011-07-01

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference has been shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups required mitigation of a high-frequency instability that otherwise limits effectiveness. In this paper, methods are presented which mitigated the observed instability, including an electromagnetic solver with tunable coefficients, its extension to accommodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is observed that choosing the frame of the wake as the frame of reference allows for higher levels of filtering or damping than is possible in other frames for the same accuracy. Detailed testing also revealed the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion. A combination of the techniques presented in this paper prove to be very efficient at controlling the instability, allowing for efficient direct modeling of 10 GeV class laser plasma accelerator stages. The methods developed in this paper may have broader application, to other Lorentz-boosted simulations and Particle-In-Cell simulations in general.

  10. Time pressure increases cooperation in competitively framed social dilemmas.

    PubMed

    Cone, Jeremy; Rand, David G

    2014-01-01

    What makes people willing to pay costs to benefit others? Does such cooperation require effortful self-control, or do automatic, intuitive processes favor cooperation? Time pressure has been shown to increase cooperative behavior in Public Goods Games, implying a predisposition towards cooperation. Consistent with the hypothesis that this predisposition results from the fact that cooperation is typically advantageous outside the lab, it has further been shown that the time pressure effect is undermined by prior experience playing lab games (where selfishness is the more advantageous strategy). Furthermore, a recent study found that time pressure increases cooperation even in a game framed as a competition, suggesting that the time pressure effect is not the result of social norm compliance. Here, we successfully replicate these findings, again observing a positive effect of time pressure on cooperation in a competitively framed game, but not when using the standard cooperative framing. These results suggest that participants' intuitions favor cooperation rather than norm compliance, and also that simply changing the framing of the Public Goods Game is enough to make it appear novel to participants and thus to restore the time pressure effect. PMID:25551386

  11. Modeling laser wakefield accelerator experiments with ultrafast particle-in-cell simulations in boosted frames

    SciTech Connect

    Martins, S. F.; Fonseca, R. A.; Vieira, J.; Silva, L. O.

    2010-05-15

    The development of new laser systems at the 10 Petawatt range will push laser wakefield accelerators to novel regimes, for which theoretical scalings predict the possibility to accelerate electron bunches up to tens of GeVs in meter-scale plasmas. Numerical simulations will play a crucial role in testing, probing, and optimizing the physical parameters and the setup of future experiments. Fully kinetic simulations are computationally very demanding, pushing the limits of today's supercomputers. In this paper, the recent developments in the OSIRIS framework [R. A. Fonseca et al., Lect. Notes Comput. Sci. 2331, 342 (2002)] are described, in particular the boosted frame scheme, which leads to a dramatic change in the computational resources required to model laser wakefield accelerators. Results from one-to-one modeling of the next generation of laser systems are discussed, including the confirmation of electron bunch acceleration to the energy frontier.

  12. 12 CFR 1805.503 - Time frame for raising match.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Time frame for raising match. 1805.503 Section 1805.503 Banks and Banking COMMUNITY DEVELOPMENT FINANCIAL INSTITUTIONS FUND, DEPARTMENT OF THE TREASURY COMMUNITY DEVELOPMENT FINANCIAL INSTITUTIONS PROGRAM Matching Funds Requirements § 1805.503...

  13. Framing health messages based on anomalies in time preference.

    PubMed

    Ortendahl, Monica; Fries, James F

    2005-08-01

    Time discounting processes and their effects are increasingly taken into account in health-related decisions. Because these effects have a potentially large impact the characteristics of discounting should also be taken into consideration when framing health messages. Research on the relationship between time and health is discussed with a special focus on discounting biases. The criteria for selection of articles were potential practical application when formulating health messages. Time discounting processes vary with individuals and contexts. Therefore, no single model is expected to describe discounting processes completely. Discounting biases appear more prevalent in health decisions than in economic decisions, even when health and monetary outcomes are matched for utility. Research on decision-making under conditions of uncertainty has documented numerous anomalies of expected utility. Analysis on the anomalies related to intertemporal choice and discounted utility (DU) include the magnitude effect, dynamic inconsistency effect, instant endowment, status quo bias, and sequence effect. Discounting biases in the formulation of preventive health messages are important. The desire for behavioral change in these programs would benefit from considering the psychological factor of discounting. Framing health messages in terms of large, important outcomes or long delays should induce lower implicit discount rates. Framing health messages as losses rather than gains, or as involving a series of outcomes rather than individual outcomes, might similarly lower the implicit discount rate used.

  14. Finite Time Shock Acceleration at Interplanetary Shocks

    NASA Astrophysics Data System (ADS)

    Channok, C.; Ruffolo, D.; Desai, M. I.; Mason, G. M.

    2004-05-01

    Observations of energetic ion acceleration at interplanetary shocks sometimes indicate a spectral rollover at ˜ 0.1 to 1 MeV nucl-1. This rollover is not well explained by finite shock width or thickness effects. At the same time, a typical timescale of diffusive shock acceleration is several days, implying that the process of shock acceleration at an interplanetary shock near Earth usually gives only a mild increase in energy to an existing seed particle population. This is consistent with a recent analysis of ACE observations that argues for a seed population at substantially higher energies than the solar wind. Therefore an explanation of typical spectra of interplanetary shock-accelerated ions requires a theory of finite-time shock acceleration, which for long times (or an unusually fast acceleration timescale) tends to the steady-state result of a power-law spectrum. We present analytic and numerical models of finite-time shock acceleration. For a given injection momentum p0, after a very short time there is only a small boost in momentum, at intermediate times the spectrum is a power law with a hump and steep cutoff at a critical momentum, and at longer times the critical momentum increases and the spectrum approaches the steady-state power law. The composition dependence of the critical momentum is different from that obtained for other cutoff mechanisms. The results are compared with observed spectra. Work in Thailand was supported by the Commission for Higher Education, the Rachadapisek Sompoj Fund of Chulalongkorn University, and the Thailand Research Fund. Work at the University of Maryland was supported by NASA contract NAS5-30927 and NASA grant PC 251428.

  15. Stability of Gabor Frames Under Small Time Hamiltonian Evolutions

    NASA Astrophysics Data System (ADS)

    de Gosson, Maurice A.; Gröchenig, Karlheinz; Romero, José Luis

    2016-06-01

    We consider Hamiltonian deformations of Gabor systems, where the window evolves according to the action of a Schrödinger propagator and the phase-space nodes evolve according to the corresponding Hamiltonian flow. We prove the stability of the frame property for small times and Hamiltonians consisting of a quadratic polynomial plus a potential in the Sjöstrand class with bounded second-order derivatives. This answers a question raised in de Gosson (Appl Comput Harmonic Anal 38(2):196-221, 2015)

  16. Realization of fertility intentions by different time frames.

    PubMed

    Dommermuth, Lars; Klobas, Jane; Lappegård, Trude

    2015-06-01

    This paper focuses on the realization of positive fertility intentions with different time frames. The analyses are based on a unique combination of survey data and information from Norwegian administrative registers on childbearing in the years following the complete selected sample. Guided by the theoretical and empirical framework of the Theory of Planned Behavior (TPB), the results suggest that a fertility intention's time frame is relevant for childbearing behaviour, but the patterns are somewhat different for respondents who were childless at the time of the interview compared to those who already had children. Overall, childless were less likely to realize their fertility intentions than parents. Following the TPB, childless may underestimate the difficulty of acting on their intentions and therefore have more difficulty realizing their intentions, versus parents who take into account their ability to manage another child. The results also show that childless with an immediate fertility intention are more likely to succeed than those with a longer-term intention. Likewise, parents with an immediate fertility intention are more likely to realize their intention during the two first years after the interview, but after four years the childbearing rate was higher among those with longer-term fertility intentions. PMID:26047988

  17. Advanced concepts in accelerator timing control

    SciTech Connect

    Frankel, R.; Salwen, C.

    1988-01-01

    The control system for the Booster accelerator presently under construction at BNL includes a timing section with serial high speed coded data distribution, computer based encoders for both real time and field driven clocks and a method of easily tracking the performance and reliability of these timing streams. We have developed a simple method for the generation of timing which operates to produce pulses which may be repeated as desired with minimal latency.

  18. Accelerated Failure-Time Models of Graduation

    ERIC Educational Resources Information Center

    Chimka, Justin R.; Wang, Qilu

    2009-01-01

    This third article in a series describing survival analysis of engineering student retention and graduation introduces accelerated failure-time as an alternative to the Cox proportional hazards model to the context of student data. The new survival analysis of graduation data presented here assumes different distributions including exponential,…

  19. 42 CFR 405.950 - Time frame for making a redetermination.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Time frame for making a redetermination. 405.950....950 Time frame for making a redetermination. (a) General rule. The contractor mails, or otherwise... decision-making time frame begins on the date the contractor receives the late-filed request...

  20. 42 CFR 405.950 - Time frame for making a redetermination.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Time frame for making a redetermination. 405.950....950 Time frame for making a redetermination. (a) General rule. The contractor mails, or otherwise... decision-making time frame begins on the date the contractor receives the late-filed request...

  1. 42 CFR 405.950 - Time frame for making a redetermination.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Time frame for making a redetermination. 405.950....950 Time frame for making a redetermination. (a) General rule. The contractor mails, or otherwise... decision-making time frame begins on the date the contractor receives the late-filed request...

  2. 42 CFR 405.950 - Time frame for making a redetermination.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Time frame for making a redetermination. 405.950....950 Time frame for making a redetermination. (a) General rule. The contractor mails, or otherwise... decision-making time frame begins on the date the contractor receives the late-filed request...

  3. Particle Acceleration by Relativistic Frame Dragging of a Magnetised Black Hole

    NASA Astrophysics Data System (ADS)

    Karas, Vladimir; Kopacek, Ondrej; Kunneriath, Devaky

    2014-06-01

    Black holes are considered to be a likely agent of acceleration of particles. Various processes have been proposed, however, the exact mechanism is still to be identified. It is conceivable that different mechanisms can operate, depending on parameters of the black hole (spin) and the environment to which the black hole is embedded (magnetic fields and plasma). We demonstrate that large-scale oblique magnetic field near a rotating (Kerr) black hole acts as an origin of magnetic layers, where the field direction changes abruptly (Karas, Kopacek, & Kunneriath 2012, 2013). Magnetic null points can develop near the ergosphere boundary by purely geometrical effects of the strong gravitational field and the frame-dragging mechanism. In consequence, particles can be accelerated efficiently by the gravito-magnetically induced electric component. The situation we discuss is relevant for starving nuclei of some galaxies which exhibit episodic accretion events, such as Sagittarius A* supermassive black hole surrounded by the large-scale structure of magnetic filaments. By the mass-scaling relation, the same process is expected to operate also near a stellar-mass black hole orbiting in a close binary system with a strongly magnetised neutron star.

  4. Reliable timing systems for computer controlled accelerators

    NASA Astrophysics Data System (ADS)

    Knott, Jürgen; Nettleton, Robert

    1986-06-01

    Over the past decade the use of computers has set new standards for control systems of accelerators with ever increasing complexity coupled with stringent reliability criteria. In fact, with very slow cycling machines or storage rings any erratic operation or timing pulse will cause the loss of precious particles and waste hours of time and effort of preparation. Thus, for the CERN linac and LEAR (Low Energy Antiproton Ring) timing system reliability becomes a crucial factor in the sense that all components must operate practically without fault for very long periods compared to the effective machine cycle. This has been achieved by careful selection of components and design well below thermal and electrical limits, using error detection and correction where possible, as well as developing "safe" decoding techniques for serial data trains. Further, consistent structuring had to be applied in order to obtain simple and flexible modular configurations with very few components on critical paths and to minimize the exchange of information to synchronize accelerators. In addition, this structuring allows the development of efficient strategies for on-line and off-line fault diagnostics. As a result, the timing system for Linac 2 has, so far, been operating without fault for three years, the one for LEAR more than one year since its final debugging.

  5. 39 CFR 775.12 - Time frames for environmental impact statement actions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 39 Postal Service 1 2011-07-01 2011-07-01 false Time frames for environmental impact statement... NATIONAL ENVIRONMENTAL POLICY ACT PROCEDURES § 775.12 Time frames for environmental impact statement... environmental impact statements received in that office during the preceding week. The minimum time periods...

  6. 39 CFR 775.12 - Time frames for environmental impact statement actions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 39 Postal Service 1 2013-07-01 2013-07-01 false Time frames for environmental impact statement... NATIONAL ENVIRONMENTAL POLICY ACT PROCEDURES § 775.12 Time frames for environmental impact statement... environmental impact statements received in that office during the preceding week. The minimum time periods...

  7. 39 CFR 775.12 - Time frames for environmental impact statement actions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 39 Postal Service 1 2014-07-01 2014-07-01 false Time frames for environmental impact statement... NATIONAL ENVIRONMENTAL POLICY ACT PROCEDURES § 775.12 Time frames for environmental impact statement... environmental impact statements received in that office during the preceding week. The minimum time periods...

  8. 39 CFR 775.12 - Time frames for environmental impact statement actions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 39 Postal Service 1 2012-07-01 2012-07-01 false Time frames for environmental impact statement... NATIONAL ENVIRONMENTAL POLICY ACT PROCEDURES § 775.12 Time frames for environmental impact statement... environmental impact statements received in that office during the preceding week. The minimum time periods...

  9. 39 CFR 775.12 - Time frames for environmental impact statement actions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Time frames for environmental impact statement... NATIONAL ENVIRONMENTAL POLICY ACT PROCEDURES § 775.12 Time frames for environmental impact statement... environmental impact statements received in that office during the preceding week. The minimum time periods...

  10. Quantum mechanics in non-inertial reference frames: Time-dependent rotations and loop prolongations

    NASA Astrophysics Data System (ADS)

    Klink, W. H.; Wickramasekara, S.

    2013-09-01

    This is the fourth in a series of papers on developing a formulation of quantum mechanics in non-inertial reference frames. This formulation is grounded in a class of unitary cocycle representations of what we have called the Galilean line group, the generalization of the Galilei group to include transformations amongst non-inertial reference frames. These representations show that in quantum mechanics, just as the case in classical mechanics, the transformations to accelerating reference frames give rise to fictitious forces. In previous work, we have shown that there exist representations of the Galilean line group that uphold the non-relativistic equivalence principle as well as representations that violate the equivalence principle. In these previous studies, the focus was on linear accelerations. In this paper, we undertake an extension of the formulation to include rotational accelerations. We show that the incorporation of rotational accelerations requires a class of loop prolongations of the Galilean line group and their unitary cocycle representations. We recover the centrifugal and Coriolis force effects from these loop representations. Loops are more general than groups in that their multiplication law need not be associative. Hence, our broad theoretical claim is that a Galilean quantum theory that holds in arbitrary non-inertial reference frames requires going beyond groups and group representations, the well-established framework for implementing symmetry transformations in quantum mechanics.

  11. 42 CFR 403.251 - Loss ratio date and time frame provisions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Loss ratio date and time frame provisions. 403.251... Certification Program: Loss Ratio Provisions § 403.251 Loss ratio date and time frame provisions. (a) Initial... procedure that provides for the impact of a variety of factors, such as lapse of policies) for loss...

  12. 42 CFR 403.251 - Loss ratio date and time frame provisions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Loss ratio date and time frame provisions. 403.251... Certification Program: Loss Ratio Provisions § 403.251 Loss ratio date and time frame provisions. (a) Initial... procedure that provides for the impact of a variety of factors, such as lapse of policies) for loss...

  13. 20 CFR 10.336 - What are the time frames for submitting bills?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false What are the time frames for submitting bills...' COMPENSATION ACT, AS AMENDED Medical and Related Benefits Medical Bills § 10.336 What are the time frames for submitting bills? To be considered for payment, bills must be submitted by the end of the calendar year...

  14. 20 CFR 10.336 - What are the time frames for submitting bills?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true What are the time frames for submitting bills...' COMPENSATION ACT, AS AMENDED Medical and Related Benefits Medical Bills § 10.336 What are the time frames for submitting bills? To be considered for payment, bills must be submitted by the end of the calendar year...

  15. 20 CFR 10.336 - What are the time frames for submitting bills?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false What are the time frames for submitting bills...' COMPENSATION ACT, AS AMENDED Medical and Related Benefits Medical Bills § 10.336 What are the time frames for submitting bills? To be considered for payment, bills must be submitted by the end of the calendar year...

  16. 20 CFR 30.421 - What are the time frames for submitting bills and reimbursement requests?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false What are the time frames for submitting bills... AMENDED Medical and Related Benefits Medical Bills § 30.421 What are the time frames for submitting bills and reimbursement requests? To be considered for payment, bills and reimbursement requests must...

  17. 20 CFR 30.421 - What are the time frames for submitting bills and reimbursement requests?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true What are the time frames for submitting bills... AMENDED Medical and Related Benefits Medical Bills § 30.421 What are the time frames for submitting bills and reimbursement requests? To be considered for payment, bills and reimbursement requests must...

  18. 20 CFR 30.421 - What are the time frames for submitting bills and reimbursement requests?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true What are the time frames for submitting bills... AMENDED Medical and Related Benefits Medical Bills § 30.421 What are the time frames for submitting bills and reimbursement requests? To be considered for payment, bills and reimbursement requests must...

  19. 20 CFR 10.336 - What are the time frames for submitting bills?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true What are the time frames for submitting bills...' COMPENSATION ACT, AS AMENDED Medical and Related Benefits Medical Bills § 10.336 What are the time frames for submitting bills? To be considered for payment, bills must be submitted by the end of the calendar year...

  20. 20 CFR 30.421 - What are the time frames for submitting bills and reimbursement requests?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false What are the time frames for submitting bills... AMENDED Medical and Related Benefits Medical Bills § 30.421 What are the time frames for submitting bills and reimbursement requests? To be considered for payment, bills and reimbursement requests must...

  1. 20 CFR 30.421 - What are the time frames for submitting bills and reimbursement requests?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false What are the time frames for submitting bills... AMENDED Medical and Related Benefits Medical Bills § 30.421 What are the time frames for submitting bills and reimbursement requests? To be considered for payment, bills and reimbursement requests must...

  2. 20 CFR 10.336 - What are the time frames for submitting bills?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false What are the time frames for submitting bills...' COMPENSATION ACT, AS AMENDED Medical and Related Benefits Medical Bills § 10.336 What are the time frames for submitting bills? To be considered for payment, bills must be submitted by the end of the calendar year...

  3. 21 CFR 814.40 - Time frames for reviewing a PMA.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Time frames for reviewing a PMA. 814.40 Section 814.40 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PREMARKET APPROVAL OF MEDICAL DEVICES FDA Action on a PMA § 814.40 Time frames...

  4. 21 CFR 814.40 - Time frames for reviewing a PMA.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Time frames for reviewing a PMA. 814.40 Section 814.40 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PREMARKET APPROVAL OF MEDICAL DEVICES FDA Action on a PMA § 814.40 Time frames...

  5. 21 CFR 814.40 - Time frames for reviewing a PMA.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Time frames for reviewing a PMA. 814.40 Section 814.40 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PREMARKET APPROVAL OF MEDICAL DEVICES FDA Action on a PMA § 814.40 Time frames...

  6. 21 CFR 814.40 - Time frames for reviewing a PMA.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Time frames for reviewing a PMA. 814.40 Section...) MEDICAL DEVICES PREMARKET APPROVAL OF MEDICAL DEVICES FDA Action on a PMA § 814.40 Time frames for reviewing a PMA. Within 180 days after receipt of an application that is accepted for filing and to...

  7. 21 CFR 814.40 - Time frames for reviewing a PMA.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Time frames for reviewing a PMA. 814.40 Section...) MEDICAL DEVICES PREMARKET APPROVAL OF MEDICAL DEVICES FDA Action on a PMA § 814.40 Time frames for reviewing a PMA. Within 180 days after receipt of an application that is accepted for filing and to...

  8. Dilaton-derived quintessence scenario leading naturally to the late-time acceleration of the Universe

    NASA Astrophysics Data System (ADS)

    Bean, R.; Magueijo, J.

    2001-09-01

    Quintessence scenarios provide a simple explanation for the observed acceleration of the Universe. Yet, explaining why acceleration did not start a long time ago remains a challenge. The idea that the transition from radiation to matter domination played a dynamical role in triggering acceleration has been put forward in various guises. We propose a simple dilaton-derived quintessence model in which temporary vacuum domination is naturally triggered by the radiation to matter transition. In this model Einstein's gravity is preserved but quintessence couples non-minimally to the cold dark matter, but not to ``visible'' matter. Such couplings have been attributed to the dilaton in the low-energy limit of string theory beyond tree level. We also show how a cosmological constant in the string frame translates into a quintessence-type of potential in the atomic frame.

  9. Effects of Time Frame on the Recall Reliability of CFS Symptoms.

    PubMed

    Evans, Meredyth; Jason, Leonard A

    2015-09-01

    This study serves as an investigation of the reliability of symptom data as reported by individuals with chronic fatigue syndrome (CFS), across three recall time frames (the past week, the past month, and the past 6 months), and at two assessment points (with 1 week in between each assessment). Multilevel model analyses were used to determine the optimal recall time frame, in terms of test -retest reliability, for each of the Fukuda et al. (1994) case defining symptoms. Results suggested that the optimal time frame for reliably reporting CFS symptoms was six months for sore throat, lymph node pain, muscle pain, post-exertional malaise, headaches, memory/concentration difficulties, and unrefreshing sleep. For joint pain, the optimal time frame was one month. Researchers who are interested in the assessment of CFS symptoms need to take recall time frame into account, especially when the intended goal is to standardize and improve the methods used to reliably and accurately diagnose this complex illness.

  10. Reference Frames and Relativity.

    ERIC Educational Resources Information Center

    Swartz, Clifford

    1989-01-01

    Stresses the importance of a reference frame in mechanics. Shows the Galilean transformation in terms of relativity theory. Discusses accelerated reference frames and noninertial reference frames. Provides examples of reference frames with diagrams. (YP)

  11. Examining the Variability of Wind Power Output in the Regulation Time Frame: Preprint

    SciTech Connect

    Hodge, B. M.; Shedd, S.; Florita, A.

    2012-08-01

    This work examines the distribution of changes in wind power for different time scales in the regulation time frame as well as the correlation of changes in power output for individual wind turbines in a wind plant.

  12. Quantum mechanics in non-inertial reference frames: Time-dependent rotations and loop prolongations

    SciTech Connect

    Klink, W.H.; Wickramasekara, S.

    2013-09-15

    This is the fourth in a series of papers on developing a formulation of quantum mechanics in non-inertial reference frames. This formulation is grounded in a class of unitary cocycle representations of what we have called the Galilean line group, the generalization of the Galilei group to include transformations amongst non-inertial reference frames. These representations show that in quantum mechanics, just as the case in classical mechanics, the transformations to accelerating reference frames give rise to fictitious forces. In previous work, we have shown that there exist representations of the Galilean line group that uphold the non-relativistic equivalence principle as well as representations that violate the equivalence principle. In these previous studies, the focus was on linear accelerations. In this paper, we undertake an extension of the formulation to include rotational accelerations. We show that the incorporation of rotational accelerations requires a class of loop prolongations of the Galilean line group and their unitary cocycle representations. We recover the centrifugal and Coriolis force effects from these loop representations. Loops are more general than groups in that their multiplication law need not be associative. Hence, our broad theoretical claim is that a Galilean quantum theory that holds in arbitrary non-inertial reference frames requires going beyond groups and group representations, the well-established framework for implementing symmetry transformations in quantum mechanics. -- Highlights: •A formulation of Galilean quantum mechanics in non-inertial reference frames is presented. •The Galilei group is generalized to infinite dimensional Galilean line group. •Loop prolongations of Galilean line group contain central extensions of Galilei group. •Unitary representations of the loops are constructed. •These representations lead to terms in the Hamiltonian corresponding to fictitious forces, including centrifugal and Coriolis

  13. Development of a cryogenic load frame for the neutron diffractometer at Takumi in Japan Proton Accelerator Research Complex.

    PubMed

    Jin, Xinzhe; Nakamoto, Tatsushi; Harjo, Stefanus; Hemmi, Tsutomu; Umeno, Takahiro; Ogitsu, Toru; Yamamoto, Akira; Sugano, Michinaka; Aizawa, Kazuya; Abe, Jun; Gong, Wu; Iwahashi, Takaaki

    2013-06-01

    To prepare for projects such as the Large Hadron Collider upgrade, International Thermonuclear Experimental Reactor and Demonstration reactor, it is important to form a clear understanding of stress-strain properties of the materials that make up superconducting magnets. Thus, we have been studying the mechanical properties of superconducting wires using neutron diffraction measurements. To simulate operational conditions such as temperature, stress, and strain, we developed a cryogenic load frame for stress-strain measurements of materials using a neutron diffractometer at Japan Proton Accelerator Research Complex (J-PARC) Takumi beam line. The maximum load that can be applied to a sample using an external driving machine is 50 kN. Using a Gifford-MacMahon cryocooler, samples can be measured down to temperatures below 10 K when loaded. In the present paper, we describe the details of the cryogenic load frame with its test results by using type-304 stainless steel wire.

  14. Development of a cryogenic load frame for the neutron diffractometer at Takumi in Japan Proton Accelerator Research Complex

    SciTech Connect

    Jin, Xinzhe; Nakamoto, Tatsushi; Ogitsu, Toru; Yamamoto, Akira; Sugano, Michinaka; Harjo, Stefanus; Aizawa, Kazuya; Abe, Jun; Gong, Wu; Iwahashi, Takaaki; Hemmi, Tsutomu; Umeno, Takahiro

    2013-06-15

    To prepare for projects such as the Large Hadron Collider upgrade, International Thermonuclear Experimental Reactor and Demonstration reactor, it is important to form a clear understanding of stress-strain properties of the materials that make up superconducting magnets. Thus, we have been studying the mechanical properties of superconducting wires using neutron diffraction measurements. To simulate operational conditions such as temperature, stress, and strain, we developed a cryogenic load frame for stress-strain measurements of materials using a neutron diffractometer at Japan Proton Accelerator Research Complex (J-PARC) Takumi beam line. The maximum load that can be applied to a sample using an external driving machine is 50 kN. Using a Gifford-MacMahon cryocooler, samples can be measured down to temperatures below 10 K when loaded. In the present paper, we describe the details of the cryogenic load frame with its test results by using type-304 stainless steel wire.

  15. Time frames and the distinction between affective and cognitive well-being.

    PubMed

    Luhmann, Maike; Hawkley, Louise C; Eid, Michael; Cacioppo, John T

    2012-08-01

    We examined whether the empirical differences between affective well-being (AWB) and cognitive well-being (CWB) might be due to (a) the use of different time frames in measures of AWB and CWB or (b) structural differences. In Study 1, a multitrait-multimethod (MTMM) analysis indicated that levels of different components are more similar but do not converge completely when the same time frame is used. In Study 2, we found that people are more likely to consider global life circumstances (as opposed to specific events and activities) when they evaluate their CWB, regardless of the specific time frame. In both studies, the time frame did not moderate the associations between AWB and CWB and important correlates (personality, life circumstances).

  16. Transformation from proper time on earth to coordinate time in solar system barycentric space-time frame of reference

    NASA Technical Reports Server (NTRS)

    Moyer, T. D.

    1976-01-01

    An expression was derived for the time transformation t - tau, where t is coordinate time in the solar system barycentric space-time frame of reference and tau is proper time obtained from a fixed atomic clock on earth. This transformation is suitable for use in the computation of high-precision earth-based range and Doppler observables of a spacecraft or celestial body located anywhere in the solar system; it can also be used in obtaining computed values of very long baseline interferometry data types. The formulation for computing range and Doppler observables, which is an explicit function of the transformation t - tau, is described briefly.

  17. Faculty Speak on the Impact of Time in Accelerated Courses

    ERIC Educational Resources Information Center

    Johnson, Carrie

    2009-01-01

    Eighteen faculty members participated in this qualitative study to determine the impact of reduced seat time in accelerated courses. The findings challenge critics who believe the accelerated delivery format compromises academic quality. The participants noted the importance of students in the learning process, emphasizing the significant workload…

  18. A Possible Approach to Inclusion of Space and Time in Frame Fields of Quantum Representations of Real and Complex Numbers

    DOE PAGES

    Benioff, Paul

    2009-01-01

    Tmore » his work is based on the field of reference frames based on quantum representations of real and complex numbers described in other work. Here frame domains are expanded to include space and time lattices. Strings of qukits are described as hybrid systems as they are both mathematical and physical systems. As mathematical systems they represent numbers. As physical systems in each frame the strings have a discrete Schrodinger dynamics on the lattices.he frame field has an iterative structure such that the contents of a stage j frame have images in a stage j - 1 (parent) frame. A discussion of parent frame images includes the proposal that points of stage j frame lattices have images as hybrid systems in parent frames.he resulting association of energy with images of lattice point locations, as hybrid systems states, is discussed. Representations and images of other physical systems in the different frames are also described.« less

  19. Measuring dwell time percentage from head-mounted eye-tracking data--comparison of a frame-by-frame and a fixation-by-fixation analysis.

    PubMed

    Vansteenkiste, Pieter; Cardon, Greet; Philippaerts, Renaat; Lenoir, Matthieu

    2015-01-01

    Although analysing software for eye-tracking data has significantly improved in the past decades, the analysis of gaze behaviour recorded with head-mounted devices is still challenging and time-consuming. Therefore, new methods have to be tested to reduce the analysis workload while maintaining accuracy and reliability. In this article, dwell time percentages to six areas of interest (AOIs), of six participants cycling on four different roads, were analysed both frame-by-frame and in a 'fixation-by-fixation' manner. The fixation-based method is similar to the classic frame-by-frame method but instead of assigning frames, fixations are assigned to one of the AOIs. Although some considerable differences were found between the two methods, a Pearson correlation of 0.930 points out a good validity of the fixation-by-fixation method. For the analysis of gaze behaviour over an extended period of time, the fixation-based approach is a valuable and time-saving alternative for the classic frame-by-frame analysis. PMID:25529829

  20. ACCELERATORS: Timing system of HIRFL-CSR

    NASA Astrophysics Data System (ADS)

    Dong, Jin-Mei; Yuan, You-Jin; Qiao, Wei-Min; Jing, Lan; Zhang, Wei

    2009-05-01

    The national science project HIRFL-CSR has recently been officially accepted. As a cyclotron and synchrotron complex, it puts some particularly high demands on the control system. There are hundreds of pieces of equipment that need to be synchronized. An integrated timing control system is built to meet these demands. The output rate and the accuracy of the controller are 16 bit/μs. The accuracy of the time delay reaches 40 ns. The timing control system is based on a typical event distribution system, which adopts the new event generation and the distribution scheme. The scheme of the timing control system with innovation points, the architecture and the implemented method are presented in the paper.

  1. Relating Time-Dependent Acceleration and Height Using an Elevator

    ERIC Educational Resources Information Center

    Kinser, Jason M.

    2015-01-01

    A simple experiment in relating a time-dependent linear acceleration function to height is explored through the use of a smartphone and an elevator. Given acceleration as a function of time, a(t), the velocity function and position functions are determined through integration as in v(t)=? a(t) dt (1) and x(t)=? v(t) dt. Mobile devices such as…

  2. An LCD driver with on-chip frame buffer and 3 times image compression

    NASA Astrophysics Data System (ADS)

    Sung, Star; Baudia, Jacques

    2008-01-01

    An LCD Driver with on-chip frame buffer and 3 times image compression codec reaching visually lossless image quality is presented. The frame buffer compression codec can encode and decode up to eight pixels in one clock cycle. Integrating a whole frame buffer with RGB=888 bits into the display driver sharply reduces power dissipated between the IO pad and PCB board at a cost of 50% IC die area increase. The existing working chip (STE2102, a ram-less LCD Driver with die size of 170mm x 12mm) is manufactured by ST Micro 0.18μm high voltage CMOS process. A new chip design with on-chip frame buffer SRAM and 3 times compression codec supporting QVGA (320x240) is completed which reduces the frame buffer SRAM density and area by a factor of ~3.0 times and cuts the power consumption of the on-chip SRAM frame buffer by ~9.0 times of which 3 times is contributed by less capacitive bit line load and another 3 times from data rate reduction from image compression. The compression codec having 25K gates in encoder and 10K in decoder accepts both YUV and RGB color formats. An on-chip color-space-conversion unit converts the decompressed YUV components with 420, 422 and 444 formats to be RGB format before driving out to be displayed. The high image quality is achieved by applying some patented proprietary compression algorithms including accurate prediction in DPCM, a Golomb-Rice like VLC coding with accurate predictive divider and an intelligent bit rate distribution control.

  3. Relating Time-Dependent Acceleration and Height Using an Elevator

    NASA Astrophysics Data System (ADS)

    Kinser, Jason M.

    2015-04-01

    A simple experiment in relating a time-dependent linear acceleration function to height is explored through the use of a smartphone and an elevator. Given acceleration as a function of time1, a(t), the velocity function and position functions are determined through integration as in v (t ) =∫ a (t ) d t (1) and x (t ) =∫ v (t ) dt. Mobile devices such as smartphones or tablets have accelerometers that capture slowly evolving acceleration with respect to time and can deliver those measurements as a CSV file. A recent example measured the oscillations of the elevator as it starts its motion.2 In the application presented here the mobile device is used to estimate the height of the elevator ride. By estimating the functional form of the acceleration of an elevator ride, it is possible to estimate the height of the ride through Eqs. (1) and (2).

  4. Time and Irreversibility in AN Accelerating Universe

    NASA Astrophysics Data System (ADS)

    Romero, Gustavo E.; Pérez, Daniela

    It is a remarkable fact that all processes occurring in the observable universe are irreversible, whereas the equations through which the fundamental laws of physics are formulated are invariant under time reversal. The emergence of irreversibility from the fundamental laws has been a topic of consideration by physicists, astronomers and philosophers since Boltzmann's formulation of his famous "H" theorem. In this paper, we shall discuss some aspects of this problem and its connection with the dynamics of spacetime, within the framework of modern cosmology. We conclude that the existence of cosmological horizons allows a coupling of the global state of the universe with the local events determined through electromagnetic processes.

  5. KALREF—A Kalman filter and time series approach to the International Terrestrial Reference Frame realization

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoping; Abbondanza, Claudio; Altamimi, Zuheir; Chin, T. Mike; Collilieux, Xavier; Gross, Richard S.; Heflin, Michael B.; Jiang, Yan; Parker, Jay W.

    2015-05-01

    The current International Terrestrial Reference Frame is based on a piecewise linear site motion model and realized by reference epoch coordinates and velocities for a global set of stations. Although linear motions due to tectonic plates and glacial isostatic adjustment dominate geodetic signals, at today's millimeter precisions, nonlinear motions due to earthquakes, volcanic activities, ice mass losses, sea level rise, hydrological changes, and other processes become significant. Monitoring these (sometimes rapid) changes desires consistent and precise realization of the terrestrial reference frame (TRF) quasi-instantaneously. Here, we use a Kalman filter and smoother approach to combine time series from four space geodetic techniques to realize an experimental TRF through weekly time series of geocentric coordinates. In addition to secular, periodic, and stochastic components for station coordinates, the Kalman filter state variables also include daily Earth orientation parameters and transformation parameters from input data frames to the combined TRF. Local tie measurements among colocated stations are used at their known or nominal epochs of observation, with comotion constraints applied to almost all colocated stations. The filter/smoother approach unifies different geodetic time series in a single geocentric frame. Fragmented and multitechnique tracking records at colocation sites are bridged together to form longer and coherent motion time series. While the time series approach to TRF reflects the reality of a changing Earth more closely than the linear approximation model, the filter/smoother is computationally powerful and flexible to facilitate incorporation of other data types and more advanced characterization of stochastic behavior of geodetic time series.

  6. Friedman—Robertson—Walker Models with Late-Time Acceleration

    NASA Astrophysics Data System (ADS)

    Abdussattar; Prajapati, S. R.

    2011-02-01

    In order to account for the observed cosmic acceleration, a modification of the ansatz for the variation of density in Friedman—Robertson—Walker (FRW) FRW models given by Islam is proposed. The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that of a modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.

  7. 42 CFR 457.1160 - Program specific review process: Time frames.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... process: Time frames. (a) Eligibility or enrollment matter. A State must complete the review of a matter... services matter. The State must ensure that reviews are completed in accordance with the medical needs of... HUMAN SERVICES (CONTINUED) STATE CHILDREN'S HEALTH INSURANCE PROGRAMS (SCHIPs) ALLOTMENTS AND GRANTS...

  8. An Agenda-Setting Time-Frame for the Civil Rights Issue, 1954-1976.

    ERIC Educational Resources Information Center

    Winter, James P.; Eyal, Chaim H.

    The role that time frame plays in the media agenda-setting process was studied by examining the single issue of civil rights over an extended period between 1954 and 1976. The public agenda was determined from 27 Gallup polls, conducted between 1954 and 1976, which asked respondents what they considered the most important issue facing the American…

  9. 42 CFR 457.1160 - Program specific review process: Time frames.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... process: Time frames. (a) Eligibility or enrollment matter. A State must complete the review of a matter... services matter. The State must ensure that reviews are completed in accordance with the medical needs of... HUMAN SERVICES (CONTINUED) STATE CHILDREN'S HEALTH INSURANCE PROGRAMS (SCHIPs) ALLOTMENTS AND GRANTS...

  10. Boosted frame PIC simulations of LWFA: ultra-fast modeling of current experiments and first studies of acceleration towards the energy frontier

    NASA Astrophysics Data System (ADS)

    Martins, Samuel

    2009-11-01

    The development of new laser systems, in the 10PW range, will push Laser Wakefield Accelerators (LWFA) to a new qualitative regime, for which theoretical scalings predict the possibility to accelerate electron bunches close to the energy frontier, with self-injected electrons in excess of 10 GeV, and above 50GeV bunches with externally injected electrons. As in the past, numerical simulations will certainly play an important role in testing, probing and optimizing the physical parameters and setup of these upscale experiments. The distances involved in these numerical experiments, however, are very demanding in terms of computational resources, so that three-dimensional fully kinetic simulations are not yet possible to (easily) accomplish. Following the work on optimized Lorentz frames by J.-L. Vay [PRL 98, 130405 (2007)], the Lorentz transformation for a boosted frame was implemented in OSIRIS [R. A. Fonseca et al, LNCS 2329, III-342 (Springer-Verlag, 2002)], leading to a dramatic change in the computational resources required to model LWFA. The critical implementation details will be described, and the main difficulties discussed. Quantitative benchmarks will be presented between boosted frame and laboratory frame simulations, and also with experimental results from Imperial College and Lawrence Livermore National Laboratory, with emphasis on the boosted frame scheme as a tool for faster design and modeling of current experiments. Finally, simulations for the scenarios possible with the next generation of laser systems will be presented, including the confirmation of electron bunch acceleration to the energy frontier.

  11. Design and implementation of timing generator of frame transfer area-array CCD camera

    NASA Astrophysics Data System (ADS)

    Zhou, Jian-kang; Chen, Xin-hua; Zhou, Wang; Shen, Wei-min

    2008-03-01

    Frame transfer area-array CCD camera is the perfect solution for high-end real-time medical, scientific and industrial applications because it has characteristics of high fill factor, low dark current, high resolving power, high sensitivity, high linear dynamic range and electronic shutter capability. Time sequences of frame transfer area-array CCD camera have two compact segments: CCD driving sequences and CCD signal processing sequences. Proper working of CCD sensor lies on good driving sequences while accurate CCD signal processing sequences ensures high quality of CCD image. The relationship among CCD camera time sequences is complex and precise. The conventional methods are uneasy to implement time sequences of Frame transfer area-array CCD. Embedded designing method is introduced in this paper and field programmable gate array device is chosen as the hardware design platform. Phase-locked loops are used for precise phase shifting and embedded logic analyzer for waveform verification. CCD driving clocks, electronic shutter signal, A/D and black pixels clamp clocks and double correlation sampling clocks have been attained on the hardware platform and this timing generator can control exposure time flexibly. High quality images have been acquired through using this timing generator on the CCD circuit system board which has been designed by our team.

  12. LCFM - LIVING COLOR FRAME MAKER: PC GRAPHICS GENERATION AND MANAGEMENT TOOL FOR REAL-TIME APPLICATIONS

    NASA Technical Reports Server (NTRS)

    Truong, L. V.

    1994-01-01

    Computer graphics are often applied for better understanding and interpretation of data under observation. These graphics become more complicated when animation is required during "run-time", as found in many typical modern artificial intelligence and expert systems. Living Color Frame Maker is a solution to many of these real-time graphics problems. Living Color Frame Maker (LCFM) is a graphics generation and management tool for IBM or IBM compatible personal computers. To eliminate graphics programming, the graphic designer can use LCFM to generate computer graphics frames. The graphical frames are then saved as text files, in a readable and disclosed format, which can be easily accessed and manipulated by user programs for a wide range of "real-time" visual information applications. For example, LCFM can be implemented in a frame-based expert system for visual aids in management of systems. For monitoring, diagnosis, and/or controlling purposes, circuit or systems diagrams can be brought to "life" by using designated video colors and intensities to symbolize the status of hardware components (via real-time feedback from sensors). Thus status of the system itself can be displayed. The Living Color Frame Maker is user friendly with graphical interfaces, and provides on-line help instructions. All options are executed using mouse commands and are displayed on a single menu for fast and easy operation. LCFM is written in C++ using the Borland C++ 2.0 compiler for IBM PC series computers and compatible computers running MS-DOS. The program requires a mouse and an EGA/VGA display. A minimum of 77K of RAM is also required for execution. The documentation is provided in electronic form on the distribution medium in WordPerfect format. A sample MS-DOS executable is provided on the distribution medium. The standard distribution medium for this program is one 5.25 inch 360K MS-DOS format diskette. The contents of the diskette are compressed using the PKWARE archiving tools

  13. Decisions, decisions: analysis of age, cohort, and time of testing on framing of risky decision options.

    PubMed

    Mayhorn, Christopher B; Fisk, Arthur D; Whittle, Justin D

    2002-01-01

    Decision making in uncertain environments is a daily challenge faced by adults of all ages. Framing decision options as either gains or losses is a common method of altering decision-making behavior. In the experiment reported here, benchmark decision-making data collected in the 1970s by Tversky and Kahneman (1981, 1988) were compared with data collected from current samples of young and older adults to determine whether behavior was consistent across time. Although differences did emerge between the benchmark and the present samples, the effect of framing on decision behavior was relatively stable. The present findings suggest that adults of all ages are susceptible to framing effects. Results also indicated that apparent age differences might be better explained by an analysis of cohort and time-of-testing effects. Actual or potential applications of this research include an understanding of how framing might influence the decision-making behavior of people of all ages in a number of applied contexts, such as product warning interactions and medical decision scenarios.

  14. Efficient Time Frame Building for Online Data Reconstruction in ALICE Experiment

    NASA Astrophysics Data System (ADS)

    Rybalchenko, A.; Al-Turany, M.; Kouzinopoulos, C.; Winckler, N.

    2015-12-01

    After the Long Shutdown 2 period, the upgraded ALICE detector at the LHC will produce more than a terabyte of data per second. The data, constituted from a continuous un-triggered stream data, have to be distributed from about 250 First Level Processor nodes (FLPs) to about 1500 Event Processing Nodes (EPNs). Each FLP receives a small subset of the detector data that is chopped in sub-time frames. One EPN needs all the fragments from the 250 FLPs to build a full time frame. An algorithm has been implemented on the FLPs with the aim of optimizing the usage of the network connecting the FLPs and EPNs. The algorithm minimizes contention when several FLPs are sending to the same EPN. An adequate traffic shaping is implemented by delaying the sending time of each FLP by a unique offset. The payloads are stored in a buffer large enough to accommodate the delay provoked by the maximum number of FLPs. As the buffers are queued for sending, the FLPs can operate with the highest efficiency. Using the time information embedded in the data any further FLP synchronization can be avoided. Moreover, zero-copy and multipart messages of ZeroMQ are used to create full time frames on the EPNs without the overhead of copying the payloads. The concept and the performance measurement of the implementation on a reference computing cluster are presented.

  15. Real-time Optical Network for Accelerator Control

    SciTech Connect

    Lee, Keun

    2012-06-27

    The timing requirements of a modern accelerator complex call for several features. The first is a system for high precision relative timing among accelerator components. Stabilized fiber links have already been demonstrated to achieve sub-10 femtoseconds relative timing precision. The second is a system for timing distribution of absolute time with sufficient precision to identify a specific RF bucket. The White Rabbit technology is a promising candidate to deliver the absolute time that is linked to the GPS clock. In this study we demonstrated that these two technologies can be combined in a way that the absolute time information can be delivered to the stabilized fiber link system. This was accomplished by researching the design of the stabilized fiber and White Rabbit systems and devising adaptation modules that facilitate co-existence of both systems in the same FPGA environment. We built a prototype system using off-the-shelf products and implemented a proof-of-concept version of the FPGA firmware. The test verified that the White Rabbit features operate correctly under the stabilized fiber system environment. This work demonstrates that turn-key femtosecond timing systems with absolute time information can be built cost effectively and deployed in various accelerator environments. This will lead to many new applications in chemistry, biology and surface dynamics, to name a few.

  16. Construal level theory and theory of planned behavior: time frame effects on salient belief generation.

    PubMed

    Lutchyn, Yuliya; Yzer, Marco

    2011-07-01

    This study tests implications of different time specifications in behavioral definitions as used in belief-elicitation research. Using construal level theory and the theory of planned behavior as complementary frameworks, the authors examined temporal frame effects on beliefs about eating fruits and vegetables and beliefs about condom use generated in a belief-elicitation study. Consistent with propositions from construal level theory, the authors found that temporal perspective (performing the behavior tomorrow, in 3 months, in 6 months, or in 5 years) affects the type of salient behavioral beliefs, such that individuals generate more feasibility (efficacy) beliefs when thinking about proximal behaviors, but more desirability (attitudinal and normative) beliefs when the behavior in question is distal. The authors' results indicate the importance of time frame in behavioral definitions in belief-elicitation research.

  17. Kuss Middle School: Expanding Time to Accelerate School Improvement

    ERIC Educational Resources Information Center

    Massachusetts 2020, 2012

    2012-01-01

    In 2004, Kuss Middle School became the first school declared "Chronically Underperforming" by the state of Massachusetts. But by 2010, Kuss had transformed itself into a model for schools around the country seeking a comprehensive turnaround strategy. Kuss is using increased learning time as the primary catalyst to accelerate learning, deepen…

  18. Quantum frames

    NASA Astrophysics Data System (ADS)

    Brown, Matthew J.

    2014-02-01

    The framework of quantum frames can help unravel some of the interpretive difficulties i the foundation of quantum mechanics. In this paper, I begin by tracing the origins of this concept in Bohr's discussion of quantum theory and his theory of complementarity. Engaging with various interpreters and followers of Bohr, I argue that the correct account of quantum frames must be extended beyond literal space-time reference frames to frames defined by relations between a quantum system and the exosystem or external physical frame, of which measurement contexts are a particularly important example. This approach provides superior solutions to key EPR-type measurement and locality paradoxes.

  19. Does the time frame between exercise influence the effectiveness of hydrotherapy for recovery?

    PubMed

    Halson, Shona L

    2011-06-01

    An increase in research investigating recovery strategies has occurred alongside the increase in usage of recovery by elite athletes. Because there is inconsistent evidence regarding the benefits of recovery on performance, it is necessary to examine research design to identify possible strategies that enhance performance in different athlete settings. The purpose of this review is to examine available recovery literature specifically related to the time frame between performance assessments to identify considerations for both research design and practical use of recovery techniques.

  20. Analysis of data systems requirements for global crop production forecasting in the 1985 time frame

    NASA Technical Reports Server (NTRS)

    Downs, S. W.; Larsen, P. A.; Gerstner, D. A.

    1978-01-01

    Data systems concepts that would be needed to implement the objective of the global crop production forecasting in an orderly transition from experimental to operational status in the 1985 time frame were examined. Information needs of users were converted into data system requirements, and the influence of these requirements on the formulation of a conceptual data system was analyzed. Any potential problem areas in meeting these data system requirements were identified in an iterative process.

  1. Subjective acceleration of time experience in everyday life across adulthood.

    PubMed

    John, Dennis; Lang, Frieder R

    2015-12-01

    Most people believe that time seems to pass more quickly as they age. Building on assumptions of socioemotional selectivity theory, we investigated whether awareness that one's future lifetime is limited is associated with one's experience of time during everyday activities across adulthood in 3 studies. In the first 2 studies (Study 1: N = 608; Study 2: N = 398), participants completed a web-based version of the day reconstruction method. In Study 3 (N = 392) participants took part in a newly developed tomorrow construction method, a web-based experimental method for assessing everyday life plans. Results confirmed that older adults' subjective interpretation of everyday episodes is that these episodes pass more quickly compared with younger adults. The subjective acceleration of time experience in old age was more pronounced during productive activities than during regenerative-consumptive activities. The age differences were partly related to limited time remaining in life. In addition, subjective acceleration of time experience was associated with positive evaluations of everyday activities. Findings suggest that subjective acceleration of time in older adults' daily lives reflects an adaptation to limitations in time remaining in life. (PsycINFO Database Record

  2. Extracting Time-Accurate Acceleration Vectors From Nontrivial Accelerometer Arrangements.

    PubMed

    Franck, Jennifer A; Blume, Janet; Crisco, Joseph J; Franck, Christian

    2015-09-01

    Sports-related concussions are of significant concern in many impact sports, and their detection relies on accurate measurements of the head kinematics during impact. Among the most prevalent recording technologies are videography, and more recently, the use of single-axis accelerometers mounted in a helmet, such as the HIT system. Successful extraction of the linear and angular impact accelerations depends on an accurate analysis methodology governed by the equations of motion. Current algorithms are able to estimate the magnitude of acceleration and hit location, but make assumptions about the hit orientation and are often limited in the position and/or orientation of the accelerometers. The newly formulated algorithm presented in this manuscript accurately extracts the full linear and rotational acceleration vectors from a broad arrangement of six single-axis accelerometers directly from the governing set of kinematic equations. The new formulation linearizes the nonlinear centripetal acceleration term with a finite-difference approximation and provides a fast and accurate solution for all six components of acceleration over long time periods (>250 ms). The approximation of the nonlinear centripetal acceleration term provides an accurate computation of the rotational velocity as a function of time and allows for reconstruction of a multiple-impact signal. Furthermore, the algorithm determines the impact location and orientation and can distinguish between glancing, high rotational velocity impacts, or direct impacts through the center of mass. Results are shown for ten simulated impact locations on a headform geometry computed with three different accelerometer configurations in varying degrees of signal noise. Since the algorithm does not require simplifications of the actual impacted geometry, the impact vector, or a specific arrangement of accelerometer orientations, it can be easily applied to many impact investigations in which accurate kinematics need to

  3. Late time solution for interacting scalar in accelerating spaces

    SciTech Connect

    Prokopec, Tomislav

    2015-11-01

    We consider stochastic inflation in an interacting scalar field in spatially homogeneous accelerating space-times with a constant principal slow roll parameter ε. We show that, if the scalar potential is scale invariant (which is the case when scalar contains quartic self-interaction and couples non-minimally to gravity), the late-time solution on accelerating FLRW spaces can be described by a probability distribution function (PDF) ρ which is a function of φ/H only, where φ=φ( x-vector ) is the scalar field and H=H(t) denotes the Hubble parameter. We give explicit late-time solutions for ρarrow ρ{sub ∞}(φ/H), and thereby find the order ε corrections to the Starobinsky-Yokoyama result. This PDF can then be used to calculate e.g. various n-point functions of the (self-interacting) scalar field, which are valid at late times in arbitrary accelerating space-times with ε= constant.

  4. Intelligent real-time CCD data processing system based on variable frame rate

    NASA Astrophysics Data System (ADS)

    Chen, Su-ting

    2009-07-01

    In order to meet the need of image shooting with CCD in unmanned aerial vehicles, a real-time high resolution CCD data processing system based on variable frame rate is designed. The system is consisted of three modules: CCD control module, data processing module and data display module. In the CCD control module, real-time flight parameters (e.g. flight height, velocity and longitude) should be received from GPS through UART (Universal Asynchronous Receiver Transmitter) and according to the corresponding flight parameters, the variable frame rate is calculated. Based on the calculated variable frame rate, CCD external synchronization control impulse signal is generated in the control of FPGA and then CCD data is read out. In the data processing module, data segmentation is designed to extract ROI (region of interest), whose resolution is equal to valid data resolution of HDTV standard conforming to SMPTE (1080i). On one hand, Ping-pong SRAM storage controller is designed in FPGA to real-time store ROI data. On the other hand, according to the need of intelligent observing, changeable window position is designed, and a flexible area of interest is obtained. In the real-time display module, a special video encoder is used to accomplish data format conversion. Data after storage is packeted to HDTV format by creating corresponding format information in FPGA. Through inner register configuration, high definition video analog signal is implemented. The entire system has been implemented in FPGA and validated. It has been used in various real-time CCD data processing situations.

  5. Occupation time statistics of the random acceleration model

    NASA Astrophysics Data System (ADS)

    Joël Ouandji Boutcheng, Hermann; Bouetou Bouetou, Thomas; Burkhardt, Theodore W.; Rosso, Alberto; Zoia, Andrea; Timoleon Crepin, Kofane

    2016-05-01

    The random acceleration model is one of the simplest non-Markovian stochastic systems and has been widely studied in connection with applications in physics and mathematics. However, the occupation time and related properties are non-trivial and not yet completely understood. In this paper we consider the occupation time T + of the one-dimensional random acceleration model on the positive half-axis. We calculate the first two moments of T + analytically and also study the statistics of T + with Monte Carlo simulations. One goal of our work was to ascertain whether the occupation time T + and the time T m at which the maximum of the process is attained are statistically equivalent. For regular Brownian motion the distributions of T + and T m coincide and are given by Lévy’s arcsine law. We show that for randomly accelerated motion the distributions of T + and T m are quite similar but not identical. This conclusion follows from the exact results for the moments of the distributions and is also consistent with our Monte Carlo simulations.

  6. Late-time acceleration in higher dimensional cosmology

    SciTech Connect

    Pahwa, Isha; Choudhury, Debajyoti; Seshadri, T.R. E-mail: debajyoti.choudhury@gmail.com

    2011-09-01

    We investigate late time acceleration of the universe in higher dimensional cosmology. The content in the universe is assumed to exert pressure which is different in the normal and extra dimensions. Cosmologically viable solutions are found to exist for simple forms of the equation of state. The parameters of the model are fixed by comparing the predictions with supernovae data. While observations stipulate that the matter exerts almost vanishing pressure in the normal dimensions, we assume that, in the extra dimensions, the equation of state is of the form P∝ρ{sup 1−γ}. For appropriate choice of parameters, a late time acceleration in the universe occurs with q{sub 0} and z{sub tr} being approximately -0.46 and 0.76 respectively.

  7. The methodology study of time accelerated irradiation of elastomers

    NASA Astrophysics Data System (ADS)

    Ito, Masayuki

    2005-07-01

    The article studied the methods how to shorten the irradiation time by increasing dose rate without changing the relationship between dose versus properties of degraded samples. The samples used were nine kinds of EPDM which have different compounding formula. The different dose of Co-γ ray was exposed to the samples. The maximum dose was 2 MGy. The reference condition to be compared with two short time test conditions is irradiation of 0.33 kGy/h at room temperature. Two methods shown below were studied as the time-accelerate irradiation conditions.

  8. Krylov-subspace acceleration of time periodic waveform relaxation

    SciTech Connect

    Lumsdaine, A.

    1994-12-31

    In this paper the author uses Krylov-subspace techniques to accelerate the convergence of waveform relaxation applied to solving systems of first order time periodic ordinary differential equations. He considers the problem in the frequency domain and presents frequency dependent waveform GMRES (FDWGMRES), a member of a new class of frequency dependent Krylov-subspace techniques. FDWGMRES exhibits many desirable properties, including finite termination independent of the number of timesteps and, for certain problems, a convergence rate which is bounded from above by the convergence rate of GMRES applied to the static matrix problem corresponding to the linear time-invariant ODE.

  9. Los Alamos Neutron Science Center (LANSCE) accelerator timing system upgrade

    SciTech Connect

    Rybarcyk, L.J.; Shelley, F.E. Jr.

    1997-10-01

    The Los Alamos Neutron Science Center (LANSCE) 800 MeV proton linear accelerator (linac) operates at a maximum repetition rate of twice the AC power line frequency, i.e. 120 Hz. The start of each machine cycle occurs a fixed delay after each zero-crossing of the AC line voltage. Fluctuations in the AC line frequency and phase are therefore present on all linac timing signals. Proper beam acceleration along the linac requires that the timing signals remain well synchronized to the AC line. For neutron chopper spectrometers, e.g., PHAROS at the Manuel Lujan Jr. Neutron Scattering Center, accurate neutron energy selection requires that precise synchronization be maintained between the beam-on-target arrival time and the neutron chopper rotor position. This is most easily accomplished when the chopper is synchronized to a stable, fixed frequency signal. A new zero-crossing circuit which employs a Phase-Locked Loop (PLL) has been developed to increase the phase and frequency stability of the linac timing signals and thereby improve neutron chopper performance while simultaneously maintaining proper linac operation. Results of timing signal data analysis and modeling and a description of the PLL circuit are presented.

  10. SLR Station Recovery, Center of Frame Motion, and Time Varying Gravity

    NASA Technical Reports Server (NTRS)

    Zelensky, Nikita P.; Lemoine, Frank G.; Chinn, Douglas S.; Melachroinos, Stavros; Wiser Beall, Jennifer; Larson, Jordan D.

    2012-01-01

    Weekly station position estimates, beginning with 1993, are derived from the ITRF2008-based SLR processing of up to four satellites: Lageos 1, Lageos2, Starlette, and Stella. Helmert parameters obtained from c omparison of weekly SLR station positions and the a-priori SLRF2008 station complement are evaluated for geocenter motion and scale. Two me thods for modeling time varying gravity are employed in the SLR satel lite POD processing, with GGM03S serving as the static gravity field. Both methods forward model atmosphere gravity derived from 6-hour ECM WF pressure data. The standard approach applies an annual 20x20 field estimated from 4 years of GRACE data, and the IERS2003 recommended linear rates for C20, C30, C40, C21, and S21. The alternate approach us es a new set of low-order/degree 4x4 coefficients estimated weekly fr om SLR & DORIS processing to 10 satellites from 1993-2012. This exper imental tvg4x4 model has been shown to improve the TOPEX, Jason-1, and Jason-2 altimeter satellite orbits,. In this paper we apply the more detailed time-variable gravity modeling to the SLR satellite POD pro cessing and subsequent reference frame analyses. For this study we will evaluate the orbit differences (periodic and secular) for the satel lites concerned, characterize the impact on the station coordinate solutions, and the impact on reference frame parameters (geocenter and s cale).

  11. Nature, nurture, or that fast food hamburger: media framing of diabetes in the New York Times from 2000 to 2010.

    PubMed

    Stefanik-Sidener, Kelsey

    2013-01-01

    Diabetes is a growing yet misunderstood health concern in the United States. This study examined the ways in which diabetes has been framed by the New York Times over the past decade. The public's perception of the causes and solutions to complex problems such as diabetes has significant implications for the way public policy interventions are viewed; therefore, understanding how diabetes is being framed in the media can be an important first step in shifting public opinion about ways to combat the disease. A content analysis of 239 articles published in the New York Times between 2000 and 2010 revealed that nearly one-third of articles failed to differentiate between type 1, type 2, and gestational diabetes, which may cause confusion given substantial differences in the root cause and treatment of each. An examination of frames used within each type of diabetes showed that the overall dominant frame across types was either a medical frame or a behavioral frame, with deficient use of a societal frame. The limited use of societal-level framing may make it difficult for the public to see the wider consequences of diabetes and decreases the likelihood of public support for policy solutions to combat the disease.

  12. Source Time Function of P-wave Acceleration

    NASA Astrophysics Data System (ADS)

    Chen, K. J.

    2015-12-01

    In this study, the site effect of time function of the Taiwan area will be invested. The recorded response function of a single earthquake will be calculated by Complex Demodulation. The path effect of each event-station pair will be estimated by using the forward method with a 3-D attenuation structure. After removing the path effect, the source frequency function of each single event will be obtained by averaging the whole station gotten. Using this source time function to calculate the path effect of the all stations, the theoretic received time frequency function can be obtained. The difference between this theoretic function and the recorded function is the site effect function of the single station. The characterics of the site effect in Taiwan area will be analyzed. Recalculate the path effect and remove the site effect of each station to get the new source time function of P-wave acceleration.

  13. Putting language back in the body: speech and gesture on three time frames.

    PubMed

    Kelly, Spencer D; Iverson, Jana M; Terranova, Joseph; Niego, Julia; Hopkins, Michael; Goldsmith, Leslie

    2002-01-01

    This article investigates the role that nonverbal actions play in language processing over 3 different time frames. First, we speculate that nonverbal actions played a role in how formal language systems emerged from our primate ancestors over evolutionary time. Next, we hypothesize that if nonverbal behaviors played a foundational role in the emergence of language over evolution, these actions should influence how children learn language in the present. Finally, we argue that nonverbal actions continue to play a role for adults in the moment-to-moment processing of language. Throughout, we take an embodied view of language and argue that the neural, cognitive, and social components of language processing are firmly grounded in bodily action. PMID:12405508

  14. Evaluating the Human Damage of Tsunami at Each Time Frame in Aggregate Units Based on GPS data

    NASA Astrophysics Data System (ADS)

    Ogawa, Y.; Akiyama, Y.; Kanasugi, H.; Shibasaki, R.; Kaneda, H.

    2016-06-01

    Assessments of the human damage caused by the tsunami are required in order to consider disaster prevention at such a regional level. Hence, there is an increasing need for the assessments of human damage caused by earthquakes. However, damage assessments in japan currently usually rely on static population distribution data, such as statistical night time population data obtained from national census surveys. Therefore, human damage estimation that take into consideration time frames have not been assessed yet. With these backgrounds, the objectives of this study are: to develop a method for estimating the population distribution of the for each time frame, based on location positioning data observed with mass GPS loggers of mobile phones, to use a evacuation and casualties models for evaluating human damage due to the tsunami, and evaluate each time frame by using the data developed in the first objective, and 3) to discuss the factors which cause the differences in human damage for each time frame. By visualizing the results, we clarified the differences in damage depending on time frame, day and area. As this study enables us to assess damage for any time frame in and high resolution, it will be useful to consider provision for various situations when an earthquake may hit, such as during commuting hours or working hours and week day or holiday.

  15. Side oblique real-time orthophotography with the 9Kx9K digital framing camera

    NASA Astrophysics Data System (ADS)

    Gorin, Brian A.

    2003-08-01

    BAE SYSTEMS has reported on a new framing camera incorporating an ultra high resolution CCD detector array comprised of 9,216 x 9,216 pixels fabricated on one silicon wafer. The detector array features a 1:2 frame-per-second readout capable of stereo imagery with Nyquist resolution of 57 lp/mm from high velocity, low altitude (V/H) airborne platforms. Flight tests demonstrated the capability of the focal plane electronics for differential image motion compensation (IMC) with Nyquist performance utilizing a focal plane shutter (FPS) to enable both nadir and significant side and forward oblique imaging angles. The impact of FPS for differential image motion compensation is evaluated with the exterior orientation calibration parameters, which include the existing shutter velocity and flight dynamics from sample mapping applications. System requirements for GPS/INS are included with the effect of vertical error and side oblique angle impact of the digital elevation map (DEM) required to create the orthophoto. Results from the differentiated "collinearity equations" which relate the image coordinates to elements of interior and exterior orientation are combined with the DEM impact to provide useful guidelines for side oblique applications. The application of real-time orthophotography is described with the implications for system requirements for side oblique orthophoto capability.

  16. Real-Time Detection and Tracking of Multiple People in Laser Scan Frames

    NASA Astrophysics Data System (ADS)

    Cui, J.; Song, X.; Zhao, H.; Zha, H.; Shibasaki, R.

    This chapter presents an approach to detect and track multiple people ro bustly in real time using laser scan frames. The detection and tracking of people in real time is a problem that arises in a variety of different contexts. Examples in clude intelligent surveillance for security purposes, scene analysis for service robot, and crowd behavior analysis for human behavior study. Over the last several years, an increasing number of laser-based people-tracking systems have been developed in both mobile robotics platforms and fixed platforms using one or multiple laser scanners. It has been proved that processing on laser scanner data makes the tracker much faster and more robust than a vision-only based one in complex situations. In this chapter, we present a novel robust tracker to detect and track multiple people in a crowded and open area in real time. First, raw data are obtained that measures two legs for each people at a height of 16 cm from horizontal ground with multiple registered laser scanners. A stable feature is extracted using accumulated distribu tion of successive laser frames. In this way, the noise that generates split and merged measurements is smoothed well, and the pattern of rhythmic swinging legs is uti lized to extract each leg. Second, a probabilistic tracking model is presented, and then a sequential inference process using a Bayesian rule is described. A sequential inference process is difficult to compute analytically, so two strategies are presented to simplify the computation. In the case of independent tracking, the Kalman fil ter is used with a more efficient measurement likelihood model based on a region coherency property. Finally, to deal with trajectory fragments we present a concise approach to fuse just a little visual information from synchronized video camera to laser data. Evaluation with real data shows that the proposed method is robust and effective. It achieves a significant improvement compared with existing laser

  17. Dynamics of supersonic microparticle impact on elastomers revealed by real–time multi–frame imaging

    PubMed Central

    Veysset, David; Hsieh, Alex J.; Kooi, Steven; Maznev, Alexei A.; Masser, Kevin A.; Nelson, Keith A.

    2016-01-01

    Understanding high–velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post–mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real–time multi–frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700–900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high–velocity impact. PMID:27156501

  18. Dynamics of supersonic microparticle impact on elastomers revealed by real–time multi–frame imaging

    NASA Astrophysics Data System (ADS)

    Veysset, David; Hsieh, Alex J.; Kooi, Steven; Maznev, Alexei A.; Masser, Kevin A.; Nelson, Keith A.

    2016-05-01

    Understanding high–velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post–mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real–time multi–frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700–900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high–velocity impact.

  19. Dynamics of supersonic microparticle impact on elastomers revealed by real-time multi-frame imaging.

    PubMed

    Veysset, David; Hsieh, Alex J; Kooi, Steven; Maznev, Alexei A; Masser, Kevin A; Nelson, Keith A

    2016-01-01

    Understanding high-velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post-mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real-time multi-frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700-900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high-velocity impact. PMID:27156501

  20. Dynamics of supersonic microparticle impact on elastomers revealed by real-time multi-frame imaging.

    PubMed

    Veysset, David; Hsieh, Alex J; Kooi, Steven; Maznev, Alexei A; Masser, Kevin A; Nelson, Keith A

    2016-05-09

    Understanding high-velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post-mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real-time multi-frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700-900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high-velocity impact.

  1. Relativistic Jets in the Radio Reference Frame Image Database. II. Blazar Jet Accelerations from the First 10 Years of Data (1994-2003)

    NASA Astrophysics Data System (ADS)

    Piner, B. G.; Pushkarev, A. B.; Kovalev, Y. Y.; Marvin, C. J.; Arenson, J. G.; Charlot, P.; Fey, A. L.; Collioud, A.; Voitsik, P. A.

    2012-10-01

    We analyze blazar jet apparent speeds and accelerations from the RDV series of astrometric and geodetic very long baseline interferometry (VLBI) experiments. From these experiments, we have produced and analyzed 2753 global VLBI images of 68 sources at 8 GHz with a median beam size of 0.9 milliarcseconds (mas) and a median of 43 epochs per source. From this sample, we analyze the motions of 225 jet components in 66 sources. The distribution of the fastest measured apparent speed in each source has a median of 8.3c and a maximum of 44c. Sources in the 2FGL Fermi LAT catalog display higher apparent speeds than those that have not been detected. On average, components farther from the core in a given source have significantly higher apparent speeds than components closer to the core; for example, for a typical source, components at ~3 mas from the core (~15 pc projected at z ~ 0.5) have apparent speeds about 50% higher than those of components at ~1 mas from the core (~5 pc projected at z ~ 0.5). We measure accelerations of components in orthogonal directions parallel and perpendicular to their average velocity vector. Parallel accelerations have significantly larger magnitudes than perpendicular accelerations, implying that observed accelerations are predominantly due to changes in the Lorentz factor (bulk or pattern) rather than projection effects from jet bending. Positive parallel accelerations are significantly more common than negative ones, so the Lorentz factor (bulk or pattern) tends to increase on the scales observed here. Observed parallel accelerations correspond to modest source frame increases in the bulk or pattern Lorentz factor.

  2. Dynamics of high-speed micro-drop impact: numerical simulations and experiments at frame-to-frame times below 100 ns.

    PubMed

    Visser, Claas Willem; Frommhold, Philipp Erhard; Wildeman, Sander; Mettin, Robert; Lohse, Detlef; Sun, Chao

    2015-03-01

    Technologies including (3D-) (bio-)printing, diesel engines, laser-induced forward transfer, and spray cleaning require optimization and therefore understanding of micrometer-sized droplets impacting at velocities beyond 10 m s(-1). However, as yet, this regime has hardly been addressed. Here we present the first time-resolved experimental investigation of microdroplet impact at velocities up to V0 = 50 m s(-1), on hydrophilic and -phobic surfaces at frame rates exceeding 10(7) frames per second. A novel method to determine the 3D-droplet profile at sub-micron resolution at the same frame rates is presented, using the fringe pattern observed from a bottom view. A numerical model, which is validated by the side- and bottom-view measurements, is employed to study the viscous boundary layer inside the droplet and the development of the rim. The spreading dynamics, the maximal spreading diameter, the boundary layer thickness, the rim formation, and the air bubble entrainment are compared to theory and previous experiments. In general, the impact dynamics are equal to millimeter-sized droplet impact for equal Reynolds-, Weber- and Stokes numbers (Re, We, and St, respectively). Using our numerical model, effective scaling laws for the progression of the boundary layer thickness and the rim diameter are provided. The dimensionless boundary layer thickness develops in time (t) according to δBL ~ D0/√Re(t/τ)0.45, and the diameter of the rim develops as DRim ~ D0/√We(t/τ)0.68, with drop diameter D0 and inertial time scale τ = D0/V0. These scalings differ from previously assumed, but never validated, values. Finally, no splash is observed, at variance with many predictions but in agreement with models including the influence of the surrounding gas. This confirms that the ambient gas properties are key ingredients for splash threshold predictions.

  3. Dynamics of high-speed micro-drop impact: numerical simulations and experiments at frame-to-frame times below 100 ns.

    PubMed

    Visser, Claas Willem; Frommhold, Philipp Erhard; Wildeman, Sander; Mettin, Robert; Lohse, Detlef; Sun, Chao

    2015-03-01

    Technologies including (3D-) (bio-)printing, diesel engines, laser-induced forward transfer, and spray cleaning require optimization and therefore understanding of micrometer-sized droplets impacting at velocities beyond 10 m s(-1). However, as yet, this regime has hardly been addressed. Here we present the first time-resolved experimental investigation of microdroplet impact at velocities up to V0 = 50 m s(-1), on hydrophilic and -phobic surfaces at frame rates exceeding 10(7) frames per second. A novel method to determine the 3D-droplet profile at sub-micron resolution at the same frame rates is presented, using the fringe pattern observed from a bottom view. A numerical model, which is validated by the side- and bottom-view measurements, is employed to study the viscous boundary layer inside the droplet and the development of the rim. The spreading dynamics, the maximal spreading diameter, the boundary layer thickness, the rim formation, and the air bubble entrainment are compared to theory and previous experiments. In general, the impact dynamics are equal to millimeter-sized droplet impact for equal Reynolds-, Weber- and Stokes numbers (Re, We, and St, respectively). Using our numerical model, effective scaling laws for the progression of the boundary layer thickness and the rim diameter are provided. The dimensionless boundary layer thickness develops in time (t) according to δBL ~ D0/√Re(t/τ)0.45, and the diameter of the rim develops as DRim ~ D0/√We(t/τ)0.68, with drop diameter D0 and inertial time scale τ = D0/V0. These scalings differ from previously assumed, but never validated, values. Finally, no splash is observed, at variance with many predictions but in agreement with models including the influence of the surrounding gas. This confirms that the ambient gas properties are key ingredients for splash threshold predictions. PMID:25607820

  4. Full-Field Spectroscopy at Megahertz-frame-rates: Application of Coherent Time-Stretch Transform

    NASA Astrophysics Data System (ADS)

    DeVore, Peter Thomas Setsuda

    Outliers or rogue events are found extensively in our world and have incredible effects. Also called rare events, they arise in the distribution of wealth (e.g., Pareto index), finance, network traffic, ocean waves, and e-commerce (selling less of more). Interest in rare optical events exploded after the sighting of optical rogue waves in laboratory experiments at UCLA. Detecting such tail events in fast streams of information necessitates real-time measurements. The Coherent Time-Stretch Transform chirps a pulsed source of radiation so that its temporal envelope matches its spectral profile (analogous to the far field regime of spatial diffraction), and the mapped spectral electric field is slow enough to be captured by a real-time digitizer. Combining this technique with spectral encoding, the time stretch technique has enabled a new class of ultra-high performance spectrometers and cameras (30+ MHz), and analog-to-digital converters that have led to the discovery of optical rogue waves and detection of cancer cells in blood with one in a million sensitivity. Conventionally, the Coherent Time-Stretch Transform maps the spectrum into the temporal electric field, but the time-dilation process along with inherent fiber losses results in reduction of peak power and loss of sensitivity, a problem exacerbated by extremely narrow molecular linewidths. The loss issue notwithstanding, in many cases the requisite dispersive optical device is not available. By extending the Coherent Time-Stretch Transform to the temporal near field, I have demonstrated, for the first time, phase-sensitive absorption spectroscopy of a gaseous sample at millions of frames per second. As the Coherent Time-Stretch Transform may capture both near and far field optical waves, it is a complete spectro-temporal optical characterization tool. This is manifested as an amplitude-dependent chirp, which implies the ability to measure the complex refractive index dispersion at megahertz frame rates. This

  5. Time-resolved measurement technique for pulsed electron beam envelope basing on framing and streaking principle

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao-Guo; Wang, Yuan; Yang, Zhi-Yong; Zhang, Huang; Wang, Yi

    2016-01-01

    The time-resolved electron beam envelope parameters, including cross sectional distribution and beam centroid position, are very important for the study of beam transmission characteristics in a magnetic field and for verifying the rationality of the magnetic field parameters employed. One kind of high time-resolved beam envelope measurement system has recently been developed, constituted of a high-speed framing camera and a streak camera. It can obtain three panoramic images of the beam and time continuous information along the given beam profile simultaneously. Recently obtained data has proved that several fast vibrations of the beam envelope along the diameter direction occur during the front and the tail parts of the electron beam. The vibration period is several nanoseconds. The effect of magnetic field on the electron beam is also observed and verified. Beam debugging experiments have proved that the existing beam transmission design is reasonable and viable. This beam envelope measurement system will establish a good foundation for beam physics research. Supported by National Natural Science Foundation of China (10675104, 11375162)

  6. Electron-transfer acceleration investigated by time resolved infrared spectroscopy.

    PubMed

    Vlček, Antonín; Kvapilová, Hana; Towrie, Michael; Záliš, Stanislav

    2015-03-17

    Ultrafast electron transfer (ET) processes are important primary steps in natural and artificial photosynthesis, as well as in molecular electronic/photonic devices. In biological systems, ET often occurs surprisingly fast over long distances of several tens of angströms. Laser-pulse irradiation is conveniently used to generate strongly oxidizing (or reducing) excited states whose reactions are then studied by time-resolved spectroscopic techniques. While photoluminescence decay and UV-vis absorption supply precise kinetics data, time-resolved infrared absorption (TRIR) and Raman-based spectroscopies have the advantage of providing additional structural information and monitoring vibrational energy flows and dissipation, as well as medium relaxation, that accompany ultrafast ET. We will discuss three cases of photoinduced ET involving the Re(I)(CO)3(N,N) moiety (N,N = polypyridine) that occur much faster than would be expected from ET theories. [Re(4-N-methylpyridinium-pyridine)(CO)3(N,N)](2+) represents a case of excited-state picosecond ET between two different ligands that remains ultrafast even in slow-relaxing solvents, beating the adiabatic limit. This is caused by vibrational/solvational excitation of the precursor state and participation of high-frequency quantum modes in barrier crossing. The case of Re-tryptophan assemblies demonstrates that excited-state Trp → *Re(II) ET is accelerated from nanoseconds to picoseconds when the Re(I)(CO)3(N,N) chromophore is appended to a protein, close to a tryptophan residue. TRIR in combination with DFT calculations and structural studies reveals an interaction between the N,N ligand and the tryptophan indole. It results in partial electronic delocalization in the precursor excited state and likely contributes to the ultrafast ET rate. Long-lived vibrational/solvational excitation of the protein Re(I)(CO)3(N,N)···Trp moiety, documented by dynamic IR band shifts, could be another accelerating factor. The last

  7. AFFECT AND THE FRAMING EFFECT WITHIN INDIVIDUALS OVER TIME: RISK TAKING IN A DYNAMIC INVESTMENT SIMULATION

    PubMed Central

    SEO, MYEONG-GU; GOLDFARB, BRENT; BARRETT, LISA FELDMAN

    2011-01-01

    We examined the role of affect (pleasant or unpleasant feelings) and decision frames (gains or losses) in risk taking in a 20-day stock investment simulation in which 101 participants rated their current feelings while making investment decisions. As predicted, affect attenuated the relationships between decision frames and risk taking. After experiencing losses, individuals made more risky choices, in keeping with the framing effect. However, this tendency decreased and/or disappeared when loss was simultaneously experienced with either pleasant or unpleasant feelings. Similarly, individuals’ tendency to avoid risk after experiencing gains disappeared or even reversed when they simultaneously experienced pleasant feelings. PMID:26412860

  8. Time-Resolved Molecular Frame Dynamics of Fixed-in-Space CS2 Molecules

    SciTech Connect

    Bisgaard, Christer; Clarkin, Owen; Wu, Guorong; Lee, Anthony; Gessner, Oliver; Hayden, Carl; Stolow, Albert

    2009-04-02

    Random orientation of molecules within a sample leads to blurred observationsof chemical reactions studied from the laboratory perspective. Methodsdeveloped for the dynamic imaging of molecular structures and processesstruggle with this, as measurements are optimally made in the molecular frame.Here we uselaser alignment to transiently fix CS2 molecules in space longenough to elucidate, in the molecular reference frame, details of ultrafast electronic vibrationaldynamics during a photochemical reaction. These three-dimensional photoelectron imaging results, combined with ongoing efforts in molecular alignment and orientation, presage a wide range of insights obtainable fromtime-resolved studies in the molecular frame.

  9. Interstellar Mapping and Acceleration Probe (IMAP) - Its Time Has Come!

    NASA Astrophysics Data System (ADS)

    Schwadron, N.; Kasper, J. C.; Mewaldt, R. A.; Moebius, E.; Opher, M.; Spence, H. E.; Zurbuchen, T.

    2014-12-01

    Our piece of cosmic real-estate, the heliosphere, is the domain of all human existence -- an astrophysical case-history of the successful evolution of life in a habitable system. By exploring our global heliosphere and its myriad interactions, we develop key physical knowledge of the interstellar interactions that influence exoplanetary habitability as well as the distant history and destiny of our solar system and world. IBEX was the first mission to explore the global heliosphere and in concert with Voyager 1 and Voyager 2 is discovering a fundamentally new and uncharted physical domain of the outer heliosphere. The enigmatic IBEX ribbon is an unanticipated discovery demonstrating that much of what we know or think we understand about the outer heliosphere needs to be revised. The next quantum leap enabled by IMAP will open new windows on the frontier of Heliophysics at a time when the space environment is rapidly evolving. IMAP with 100 times the combined resolution and sensitivity of IBEX will discover the substructure of the IBEX ribbon and will reveal in unprecedented resolution global maps of our heliosphere. The remarkable synergy between IMAP, Voyager 1 and Voyager 2 will remain for at least the next decade as Voyager 1 pushes further into the interstellar domain and Voyager 2 moves through the heliosheath. Voyager 2 moves outward in the vicinity of the IBEX ribbon and its plasma measurements will create singular opportunities for discovery in the context of IMAP's global measurements. IMAP, like ACE before it, will be a keystone of the Heliophysics System Observatory by providing comprehensive cosmic ray, energetic particle, pickup ion, suprathermal ion, neutral atom, solar wind, solar wind heavy ion, and magnetic field observations to diagnose the changing space environment and understand the fundamental origins of particle acceleration. Thus, IMAP is a mission whose time has come. IMAP is the highest ranked next Solar Terrestrial Probe in the Decadal

  10. Sediment identification using free fall penetrometer acceleration-time histories

    NASA Astrophysics Data System (ADS)

    Mulukutla, Gopal K.; Huff, Lloyd C.; Melton, Jeffrey S.; Baldwin, Kenneth C.; Mayer, Larry A.

    2011-09-01

    Knowledge of physical properties of near-surface sediments is an important requirement for many studies of the seafloor. Dynamic or Free Fall Penetrometers (FFP), instrumented with accelerometers, are widely used to assess the mechanical properties of the sediment by deriving penetration resistance from the deceleration response of the probe as it impacts and embeds the seabed. Other field investigations, a priori knowledge or a very basic description of the type of sediment (such as a description of the sediment as soft, medium or hard) derived from studying the deceleration response (accelerometer-time histories) are used for sediment identification prior to the application of an appropriate strength determination model. In many cases this information is site-specific and in others the penetration resistance is overestimated due to the dilatory effects observed in sediment with an undetected grain fraction. In this study variables affecting a dynamic penetrometer-sediment interaction system are identified. Using data from field investigations and literature we found a relationship among five variables: peak acceleration, embedment depth, total embedment time, velocity of impact and grain size. This is used to formulate a sediment identification model. The model accounts for variables that may vary widely within one deployment and it can be applied to other FFPs with different physical characteristics (such as a different mass or size). This may lead to the increased use of FFP as a deployment tool for rapid in situ characterization of the seafloor.

  11. Frame-Transfer Gating Raman Spectroscopy for Time-Resolved Multiscalar Combustion Diagnostics

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet; Fischer, David G.; Kojima, Jun

    2011-01-01

    Accurate experimental measurement of spatially and temporally resolved variations in chemical composition (species concentrations) and temperature in turbulent flames is vital for characterizing the complex phenomena occurring in most practical combustion systems. These diagnostic measurements are called multiscalar because they are capable of acquiring multiple scalar quantities simultaneously. Multiscalar diagnostics also play a critical role in the area of computational code validation. In order to improve the design of combustion devices, computational codes for modeling turbulent combustion are often used to speed up and optimize the development process. The experimental validation of these codes is a critical step in accepting their predictions for engine performance in the absence of cost-prohibitive testing. One of the most critical aspects of setting up a time-resolved stimulated Raman scattering (SRS) diagnostic system is the temporal optical gating scheme. A short optical gate is necessary in order for weak SRS signals to be detected with a good signal- to-noise ratio (SNR) in the presence of strong background optical emissions. This time-synchronized optical gating is a classical problem even to other spectroscopic techniques such as laser-induced fluorescence (LIF) or laser-induced breakdown spectroscopy (LIBS). Traditionally, experimenters have had basically two options for gating: (1) an electronic means of gating using an image intensifier before the charge-coupled-device (CCD), or (2) a mechanical optical shutter (a rotary chopper/mechanical shutter combination). A new diagnostic technology has been developed at the NASA Glenn Research Center that utilizes a frame-transfer CCD sensor, in conjunction with a pulsed laser and multiplex optical fiber collection, to realize time-resolved Raman spectroscopy of turbulent flames that is free from optical background noise (interference). The technology permits not only shorter temporal optical gating (down

  12. Time-dependent Electron Acceleration in Blazar Transients: X-Ray Time Lags and Spectral Formation

    NASA Astrophysics Data System (ADS)

    Lewis, Tiffany R.; Becker, Peter A.; Finke, Justin D.

    2016-06-01

    Electromagnetic radiation from blazar jets often displays strong variability, extending from radio to γ-ray frequencies. In a few cases, this variability has been characterized using Fourier time lags, such as those detected in the X-rays from Mrk 421 using BeppoSAX. The lack of a theoretical framework to interpret the data has motivated us to develop a new model for the formation of the X-ray spectrum and the time lags in blazar jets based on a transport equation including terms describing stochastic Fermi acceleration, synchrotron losses, shock acceleration, adiabatic expansion, and spatial diffusion. We derive the exact solution for the Fourier transform of the electron distribution and use it to compute the Fourier transform of the synchrotron radiation spectrum and the associated X-ray time lags. The same theoretical framework is also used to compute the peak flare X-ray spectrum, assuming that a steady-state electron distribution is achieved during the peak of the flare. The model parameters are constrained by comparing the theoretical predictions with the observational data for Mrk 421. The resulting integrated model yields, for the first time, a complete first-principles physical explanation for both the formation of the observed time lags and the shape of the peak flare X-ray spectrum. It also yields direct estimates of the strength of the shock and the stochastic magnetohydrodynamical wave acceleration components in the Mrk 421 jet.

  13. Late time cosmic acceleration from natural infrared cutoff

    NASA Astrophysics Data System (ADS)

    Gorji, Mohammad Ali

    2016-09-01

    In this paper, inspired by the ultraviolet deformation of the Friedmann-Lemaître-Robertson-Walker geometry in loop quantum cosmology, we formulate an infrared-modified cosmological model. We obtain the associated deformed Friedmann and Raychaudhuri equations and we show that the late time cosmic acceleration can be addressed by the infrared corrections. As a particular example, we applied the setup to the case of matter dominated universe. This model has the same number of parameters as ΛCDM, but a dynamical dark energy generates in the matter dominated era at the late time. According to our model, as the universe expands, the energy density of the cold dark matter dilutes and when the Hubble parameter approaches to its minimum, the infrared effects dominate such that the effective equation of state parameter smoothly changes from weff = 0 to weff = - 2. Interestingly and nontrivially, the unstable de Sitter phase with weff = - 1 is corresponding to Ωm =Ωd = 0.5 and the universe crosses the phantom divide from the quintessence phase with weff > - 1 and Ωm >Ωd to the phantom phase with weff < - 1 and Ωm <Ωd which shows that the model is observationally viable. The results show that the universe finally ends up in a big rip singularity for a finite time proportional to the inverse of the minimum of the Hubble parameter. Moreover, we consider the dynamical stability of the model and we show that the universe starts from the matter dominated era at the past attractor with weff = 0 and ends up in a future attractor at the big rip with weff = - 2.

  14. Convergence Acceleration for Multistage Time-Stepping Schemes

    NASA Technical Reports Server (NTRS)

    Swanson, R. C.; Turkel, Eli L.; Rossow, C-C; Vasta, V. N.

    2006-01-01

    The convergence of a Runge-Kutta (RK) scheme with multigrid is accelerated by preconditioning with a fully implicit operator. With the extended stability of the Runge-Kutta scheme, CFL numbers as high as 1000 could be used. The implicit preconditioner addresses the stiffness in the discrete equations associated with stretched meshes. Numerical dissipation operators (based on the Roe scheme, a matrix formulation, and the CUSP scheme) as well as the number of RK stages are considered in evaluating the RK/implicit scheme. Both the numerical and computational efficiency of the scheme with the different dissipation operators are discussed. The RK/implicit scheme is used to solve the two-dimensional (2-D) and three-dimensional (3-D) compressible, Reynolds-averaged Navier-Stokes equations. In two dimensions, turbulent flows over an airfoil at subsonic and transonic conditions are computed. The effects of mesh cell aspect ratio on convergence are investigated for Reynolds numbers between 5.7 x 10(exp 6) and 100.0 x 10(exp 6). Results are also obtained for a transonic wing flow. For both 2-D and 3-D problems, the computational time of a well-tuned standard RK scheme is reduced at least a factor of four.

  15. Timing of recent accelerations of Pine Island Glacier, Antarctica

    USGS Publications Warehouse

    Joughin, I.; Rignot, E.; Rosanova, C.E.; Lucchitta, B.K.; Bohlander, J.

    2003-01-01

    We have used Interferometric Synthetic Aperture Radar (InSAR) data and sequential Landsat imagery to identify and temporally constrain two acceleration events on Pine Island Glacier (PIG). These two events are separated by a period of at least seven years (1987 - 1994). The change in discharge between two flux gates indicates that the majority of the increase in discharge associated with the second acceleration originates well inland (>80 km) from the grounding line. An analysis indicates that changes in driving stress consistent with observed thinning rates are sufficient in magnitude to explain much of the acceleration.

  16. Visual reaction times during prolonged angular acceleration parallel the subjective perception of rotation

    NASA Technical Reports Server (NTRS)

    Mattson, D. L.

    1975-01-01

    The effect of prolonged angular acceleration on choice reaction time to an accelerating visual stimulus was investigated, with 10 commercial airline pilots serving as subjects. The pattern of reaction times during and following acceleration was compared with the pattern of velocity estimates reported during identical trials. Both reaction times and velocity estimates increased at the onset of acceleration, declined prior to the termination of acceleration, and showed an aftereffect. These results are inconsistent with the torsion-pendulum theory of semicircular canal function and suggest that the vestibular adaptation is of central origin.

  17. Optical cell tracking analysis using a straight-forward approach to minimize processing time for high frame rate data.

    PubMed

    Seeto, Wen Jun; Lipke, Elizabeth Ann

    2016-03-01

    Tracking of rolling cells via in vitro experiment is now commonly performed using customized computer programs. In most cases, two critical challenges continue to limit analysis of cell rolling data: long computation times due to the complexity of tracking algorithms and difficulty in accurately correlating a given cell with itself from one frame to the next, which is typically due to errors caused by cells that either come close in proximity to each other or come in contact with each other. In this paper, we have developed a sophisticated, yet simple and highly effective, rolling cell tracking system to address these two critical problems. This optical cell tracking analysis (OCTA) system first employs ImageJ for cell identification in each frame of a cell rolling video. A custom MATLAB code was written to use the geometric and positional information of all cells as the primary parameters for matching each individual cell with itself between consecutive frames and to avoid errors when tracking cells that come within close proximity to one another. Once the cells are matched, rolling velocity can be obtained for further analysis. The use of ImageJ for cell identification eliminates the need for high level MATLAB image processing knowledge. As a result, only fundamental MATLAB syntax is necessary for cell matching. OCTA has been implemented in the tracking of endothelial colony forming cell (ECFC) rolling under shear. The processing time needed to obtain tracked cell data from a 2 min ECFC rolling video recorded at 70 frames per second with a total of over 8000 frames is less than 6 min using a computer with an Intel® Core™ i7 CPU 2.80 GHz (8 CPUs). This cell tracking system benefits cell rolling analysis by substantially reducing the time required for post-acquisition data processing of high frame rate video recordings and preventing tracking errors when individual cells come in close proximity to one another. PMID:27036782

  18. Optical cell tracking analysis using a straight-forward approach to minimize processing time for high frame rate data

    NASA Astrophysics Data System (ADS)

    Seeto, Wen Jun; Lipke, Elizabeth Ann

    2016-03-01

    Tracking of rolling cells via in vitro experiment is now commonly performed using customized computer programs. In most cases, two critical challenges continue to limit analysis of cell rolling data: long computation times due to the complexity of tracking algorithms and difficulty in accurately correlating a given cell with itself from one frame to the next, which is typically due to errors caused by cells that either come close in proximity to each other or come in contact with each other. In this paper, we have developed a sophisticated, yet simple and highly effective, rolling cell tracking system to address these two critical problems. This optical cell tracking analysis (OCTA) system first employs ImageJ for cell identification in each frame of a cell rolling video. A custom MATLAB code was written to use the geometric and positional information of all cells as the primary parameters for matching each individual cell with itself between consecutive frames and to avoid errors when tracking cells that come within close proximity to one another. Once the cells are matched, rolling velocity can be obtained for further analysis. The use of ImageJ for cell identification eliminates the need for high level MATLAB image processing knowledge. As a result, only fundamental MATLAB syntax is necessary for cell matching. OCTA has been implemented in the tracking of endothelial colony forming cell (ECFC) rolling under shear. The processing time needed to obtain tracked cell data from a 2 min ECFC rolling video recorded at 70 frames per second with a total of over 8000 frames is less than 6 min using a computer with an Intel® Core™ i7 CPU 2.80 GHz (8 CPUs). This cell tracking system benefits cell rolling analysis by substantially reducing the time required for post-acquisition data processing of high frame rate video recordings and preventing tracking errors when individual cells come in close proximity to one another.

  19. TIME-DEPENDENT STOCHASTIC ACCELERATION MODEL FOR FERMI BUBBLES

    SciTech Connect

    Sasaki, Kento; Asano, Katsuaki; Terasawa, Toshio E-mail: asanok@icrr.u-tokyo.ac.jp

    2015-12-01

    We study stochastic acceleration models for the Fermi bubbles. Turbulence is excited just behind the shock front via Kelvin–Helmholtz, Rayleigh–Taylor, or Richtmyer–Meshkov instabilities, and plasma particles are continuously accelerated by the interaction with the turbulence. The turbulence gradually decays as it goes away from the shock fronts. Adopting a phenomenological model for the stochastic acceleration, we explicitly solve the temporal evolution of the particle energy distribution in the turbulence. Our results show that the spatial distribution of high-energy particles is different from those for a steady solution. We also show that the contribution of electrons that escaped from the acceleration regions significantly softens the photon spectrum. The photon spectrum and surface brightness profile are reproduced by our models. If the escape efficiency is very high, the radio flux from the escaped low-energy electrons can be comparable to that of the WMAP haze. We also demonstrate hadronic models with the stochastic acceleration, but they are unlikely in the viewpoint of the energy budget.

  20. Generalized Radar 4-COORDINATES and Equal-Time Cauchy Surfaces for Arbitrary Accelerated Observers

    NASA Astrophysics Data System (ADS)

    Alba, David; Lusanna, Luca

    All existing 4-coordinate systems centered on the world-line of an accelerated observer are only locally defined, as for Fermi coordinates both in special and general relativity. As a consequence, it is not known how non-inertial observers can build equal-time surfaces which (a) correspond to a conventional observer-dependent definition of synchronization of distant clocks, and (b) are good Cauchy surfaces for Maxwell equations. Another type of coordinate singularities generating the same problems are those connected to the relativistic rotating coordinate systems used in the treatment of the rotating disk and the Sagnac effect. We show that the use of Hamiltonian methods based on 3+1 splittings of space-time allows one to define as many observer-dependent globally defined radar 4-coordinate systems as nice foliations of space-time with space-like hyper-surfaces admissible according to Møller (for instance, only the differentially rotating relativistic coordinate system, but not the rigidly rotating ones of non-relativistic physics, are allowed). All these conventional notions of an instantaneous 3-space for an arbitrary observer can be empirically defined by introducing generalizations of the Einstein ½ convention for clock synchronization in inertial frames. Each admissible 3+1 splitting has two naturally associated congruences of time-like observers: as a consequence every 3+1 splitting gives rise to non-rigid non-inertial frames centered on any one of these observers. Only for Eulerian observers are the simultaneity leaves orthogonal to the observer world-line. When there is a Lagrangian description of an isolated relativistic system, its reformulation as a parametrized Minkowski theory allows one to show that all the admissible synchronization conventions are gauge equivalent, as also happens in the canonical metric and tetrad gravity, where, however, the chrono-geometrical structure of space-time is dynamically determined. The framework developed in this

  1. Accelerating Child Survival and Development in Dark Times.

    ERIC Educational Resources Information Center

    Grant, James P.

    Measures were proposed that would enable UNICEF, in association with others and despite prevailing difficult economic circumstances, to more effectively bring well-being and hope to hundreds of millions of children. Specific proposals were designed to help most countries accelerate child survival and development. Most particularly, it was…

  2. Effects of angular acceleration on man - Choice reaction time using visual and rotary motion information

    NASA Technical Reports Server (NTRS)

    Clark, B.; Stewart, J. D.

    1974-01-01

    This experiment was concerned with the effects of rotary acceleration on choice reaction time (RTc) to the motion of a luminous line on a cathode-ray tube. Specifically, it compared the (RTc) to rotary acceleration alone, visual acceleration alone, and simultaneous, double stimulation by both rotary and visual acceleration. Thirteen airline pilots were rotated about an earth-vertical axis in a precision rotation device while they observed a vertical line. The stimuli were 7 rotary and visual accelerations which were matched for rise time. The pilot responded as quickly as possible by displacing a vertical controller to the right or left. The results showed a decreasing (RTc) with increasing acceleration for all conditions, while the (RTc) to rotary motion alone was substantially longer than for all other conditions. The (RTc) to the double stimulation was significantly longer than that for visual acceleration alone.

  3. MOSFET solid state switching circuit improves the 0 to 99% rise time for framing camera deflection electronics

    SciTech Connect

    Rivera, A.T.; Thomas, S.

    1996-09-01

    We have improved the 0 to 99% rise time voltage on our 2 frame deflection plates from 160 to 65 nS with the addition of a peaking circuit that works in conjunction with our primary 2 frame deflection circuitry. Our peaking technique has applications to other HV pulsers including those which must drive 51 ohm loads. Generally, rise time voltages are measured between 10 and 90%. To minimize the camera image blur resulting from the dynamic influence of deflection plate potentials acting on photocathode electrons, it was necessary to design a circuit that would rise from 0 to the 99% voltage level in under 100nS. Once this voltage was reached, it was necessary to stay within 1% of the attained voltage level for a duration of 1 uS. This was accomplished with the use of MOSFET solid state switching.

  4. Minimum time acceleration of aircraft turbofan engines by using an algorithm based on nonlinear programming

    NASA Technical Reports Server (NTRS)

    Teren, F.

    1977-01-01

    Minimum time accelerations of aircraft turbofan engines are presented. The calculation of these accelerations was made by using a piecewise linear engine model, and an algorithm based on nonlinear programming. Use of this model and algorithm allows such trajectories to be readily calculated on a digital computer with a minimal expenditure of computer time.

  5. Rotary acceleration of a subject inhibits choice reaction time to motion in peripheral vision

    NASA Technical Reports Server (NTRS)

    Borkenhagen, J. M.

    1974-01-01

    Twelve pilots were tested in a rotation device with visual simulation, alone and in combination with rotary stimulation, in experiments with variable levels of acceleration and variable viewing angles, in a study of the effect of S's rotary acceleration on the choice reaction time for an accelerating target in peripheral vision. The pilots responded to the direction of the visual motion by moving a hand controller to the right or left. Visual-plus-rotary stimulation required a longer choice reaction time, which was inversely related to the level of acceleration and directly proportional to the viewing angle.

  6. Future evolution and finite-time singularities in F(R) gravity unifying inflation and cosmic acceleration

    SciTech Connect

    Nojiri, Shin'ichi; Odintsov, Sergei D.

    2008-08-15

    We study the future evolution of quintessence/phantom-dominated epoch in modified F(R) gravity which unifies the early-time inflation with late-time acceleration and which is consistent with observational tests. Using the reconstruction technique it is demonstrated that there are models where any known (big rip, II, III, or IV type) singularity may classically occur. From another side, in Einstein frame (scalar-tensor description) only IV type singularity occurs. Near the singularity the classical description breaks up, and it is demonstrated that quantum effects act against the singularity and may prevent its appearance. The realistic F(R) gravity which is future singularity free is proposed. We point out that additional modification of any F(R) gravity by the terms relevant at the early universe is possible, in such a way that future singularity does not occur even classically.

  7. An accelerated failure time model for investigating pedestrian crossing behavior and waiting times at signalized intersections.

    PubMed

    Yang, Xiaobao; Abdel-Aty, Mohamed; Huan, Mei; Peng, Yichuan; Gao, Ziyou

    2015-09-01

    The waiting process is crucial to pedestrians in the street-crossing behavior. Once pedestrians terminate their waiting behavior during the red light period, they would cross against the red light and put themselves in danger. A joint hazard-based duration model is developed to investigate the effect of various covariates on pedestrian crossing behavior and to estimate pedestrian waiting times at signalized intersections. A total of 1181 pedestrians approaching the intersections during red light periods were observed in Beijing, China. Pedestrian crossing behaviors are classified into immediate crossing behavior and waiting behavior. The probability and effect of various covariates for pedestrians' immediate crossing behavior are identified by a logit model. Four accelerated failure time duration models based on the exponential, Weibull, lognormal and log-logistic distributions are proposed to examine the significant risk factors affecting duration times for pedestrians' waiting behavior. A joint duration model is developed to estimate pedestrian waiting times. Moreover, unobserved heterogeneity is considered in the proposed model. The results indicate that the Weibull AFT model with shared frailty is appropriate for modelling pedestrian waiting durations. Failure to account for heterogeneity would significantly underestimate the effects of covariates on waiting duration times. The proposed model provides a better understanding of pedestrian crossing behavior and more accurate estimation of pedestrian waiting times. It may be applicable in traffic system analysis in developing countries with high flow of mixed traffic.

  8. Galileon gravity and its relevance to late time cosmic acceleration

    SciTech Connect

    Gannouji, Radouane; Sami, M.

    2010-07-15

    We consider the covariant Galileon gravity taking into account the third order and fourth order scalar field Lagrangians L{sub 3}({pi}) and L{sub 4}({pi}), consisting of three and four {pi}'s with four and five derivatives acting on them, respectively. The background dynamical equations are set up for the system under consideration and the stability of the self-accelerating solution is demonstrated in a general setting. We extended this study to the general case of the fifth order theory. For the spherically symmetric static background, we spell out conditions for the suppression of fifth force effects mediated by the Galileon field {pi}. We study field perturbations in the fixed background and investigate the conditions for their causal propagation. We also briefly discuss metric fluctuations and derive an evolution equation for matter perturbations in Galileon gravity.

  9. Automating Frame Analysis

    SciTech Connect

    Sanfilippo, Antonio P.; Franklin, Lyndsey; Tratz, Stephen C.; Danielson, Gary R.; Mileson, Nicholas D.; Riensche, Roderick M.; McGrath, Liam

    2008-04-01

    Frame Analysis has come to play an increasingly stronger role in the study of social movements in Sociology and Political Science. While significant steps have been made in providing a theory of frames and framing, a systematic characterization of the frame concept is still largely lacking and there are no rec-ognized criteria and methods that can be used to identify and marshal frame evi-dence reliably and in a time and cost effective manner. Consequently, current Frame Analysis work is still too reliant on manual annotation and subjective inter-pretation. The goal of this paper is to present an approach to the representation, acquisition and analysis of frame evidence which leverages Content Analysis, In-formation Extraction and Semantic Search methods to provide a systematic treat-ment of a Frame Analysis and automate frame annotation.

  10. Bunching in time at the ATLAS (Argonne Tandem-Linac Accelerator System) accelerator

    SciTech Connect

    Pardo, R.

    1986-01-01

    The ability to manipulate the energy spread and time width of the beam from the ATLAS linac is an important feature used by the experimental program at Argonne. The time resolution which can be obtained on target has been shown to be less than 150 ps. for all beams through /sup 58/Ni. The fundamental ideas which apply to the bunching of heavy ion beams are described and the limitations and capabilities of the bunching system are discussed. A sequential guide for obtaining good timing on target is included.

  11. GPU accelerated real-time multi-functional spectral-domain optical coherence tomography system at 1300 nm.

    PubMed

    Wang, Yan; Oh, Christian M; Oliveira, Michael C; Islam, M Shahidul; Ortega, Arthur; Park, B Hyle

    2012-07-01

    We present a GPU accelerated multi-functional spectral domain optical coherence tomography system at 1300 nm. The system is capable of real-time processing and display of every intensity image, comprised of 512 pixels by 2048 A-lines acquired at 20 frames per second. The update rate for all four images with size of 512 pixels by 2048 A-lines simultaneously (intensity, phase retardation, flow and en face view) is approximately 10 frames per second. Additionally, we report for the first time the characterization of phase retardation and diattenuation by a sample comprised of a stacked set of polarizing film and wave plate. The calculated optic axis orientation, phase retardation and diattenuation match well with expected values. The speed of each facet of the multi-functional OCT CPU-GPU hybrid acquisition system, intensity, phase retardation, and flow, were separately demonstrated by imaging a horseshoe crab lateral compound eye, a non-uniformly heated chicken muscle, and a microfluidic device. A mouse brain with thin skull preparation was imaged in vivo and demonstrated the capability of the system for live multi-functional OCT visualization. PMID:22772175

  12. GPU accelerated real-time multi-functional spectral-domain optical coherence tomography system at 1300 nm.

    PubMed

    Wang, Yan; Oh, Christian M; Oliveira, Michael C; Islam, M Shahidul; Ortega, Arthur; Park, B Hyle

    2012-07-01

    We present a GPU accelerated multi-functional spectral domain optical coherence tomography system at 1300 nm. The system is capable of real-time processing and display of every intensity image, comprised of 512 pixels by 2048 A-lines acquired at 20 frames per second. The update rate for all four images with size of 512 pixels by 2048 A-lines simultaneously (intensity, phase retardation, flow and en face view) is approximately 10 frames per second. Additionally, we report for the first time the characterization of phase retardation and diattenuation by a sample comprised of a stacked set of polarizing film and wave plate. The calculated optic axis orientation, phase retardation and diattenuation match well with expected values. The speed of each facet of the multi-functional OCT CPU-GPU hybrid acquisition system, intensity, phase retardation, and flow, were separately demonstrated by imaging a horseshoe crab lateral compound eye, a non-uniformly heated chicken muscle, and a microfluidic device. A mouse brain with thin skull preparation was imaged in vivo and demonstrated the capability of the system for live multi-functional OCT visualization.

  13. Subjective Acceleration of Time Experience in Everyday Life across Adulthood

    ERIC Educational Resources Information Center

    John, Dennis; Lang, Frieder R.

    2015-01-01

    Most people believe that time seems to pass more quickly as they age. Building on assumptions of socioemotional selectivity theory, we investigated whether awareness that one's future lifetime is limited is associated with one's experience of time during everyday activities across adulthood in 3 studies. In the first 2 studies (Study 1: N = 608;…

  14. Time-dependent shock acceleration of particles. Effect of the time-dependent injection, with application to supernova remnants

    NASA Astrophysics Data System (ADS)

    Petruk, O.; Kopytko, B.

    2016-11-01

    Three approaches are considered to solve the equation which describes the time-dependent diffusive shock acceleration of test particles at the non-relativistic shocks. At first, the solution of Drury for the particle distribution function at the shock is generalized to any relation between the acceleration time-scales upstream and downstream and for the time-dependent injection efficiency. Three alternative solutions for the spatial dependence of the distribution function are derived. Then, the two other approaches to solve the time-dependent equation are presented, one of which does not require the Laplace transform. At the end, our more general solution is discussed, with a particular attention to the time-dependent injection in supernova remnants. It is shown that, comparing to the case with the dominant upstream acceleration time-scale, the maximum momentum of accelerated particles shifts towards the smaller momenta with increase of the downstream acceleration time-scale. The time-dependent injection affects the shape of the particle spectrum. In particular, (i) the power-law index is not solely determined by the shock compression, in contrast to the stationary solution; (ii) the larger the injection efficiency during the first decades after the supernova explosion, the harder the particle spectrum around the high-energy cutoff at the later times. This is important, in particular, for interpretation of the radio and gamma-ray observations of supernova remnants, as demonstrated on a number of examples.

  15. Demonstration of 11-ps exposure time of a framing camera using pulse-dilation technology and a magnetic lens

    NASA Astrophysics Data System (ADS)

    Bai, Yanli; Long, Jinghua; Liu, Jinyuan; Cai, Houzhi; Niu, Lihong; Zhang, Dongfang; Ma, Xue; Liu, Dan; Yang, Qinlao; Niu, Hanben

    2015-12-01

    A framing camera with high temporal and spatial resolution is demonstrated using pulse-dilation technology and a magnetic lens. The magnetic field of the magnetic lens is simulated using LORENTZ-3EM software, and the magnetic field distribution on-axis is similar to a Gaussian function. The temporal and spatial resolutions of the instrument are measured using light at the wavelength of 266 nm from a frequency tripled femtosecond laser. The measured exposure time of this camera is ˜11 ps, and the spatial resolution is better than 100 μm.

  16. Time Acceleration Methods for Advection on the Cubed Sphere

    SciTech Connect

    Archibald, Richard K; Evans, Katherine J; White III, James B; Drake, John B

    2009-01-01

    Climate simulation will not grow to the ultrascale without new algorithms to overcome the scalability barriers blocking existing implementations. Until recently, climate simulations concentrated on the question of whether the climate is changing. The emphasis is now shifting to impact assessments, mitigation and adaptation strategies, and regional details. Such studies will require significant increases in spatial resolution and model complexity while maintaining adequate throughput. The barrier to progress is the resulting decrease in time step without increasing single-thread performance. In this paper we demonstrate how to overcome this time barrier for the first standard test defined for the shallow-water equations on a sphere. This paper explains how combining a multiwavelet discontinuous Galerkin method with exact linear part time-evolution schemes can overcome the time barrier for advection equations on a sphere. The discontinuous Galerkin method is a high-order method that is conservative, flexible, and scalable. The addition of multiwavelets to discontinuous Galerkin provides a hierarchical scale structure that can be exploited to improve computational efficiency in both the spatial and temporal dimensions. Exact linear part time-evolution schemes are explicit schemes that remain stable for implicit-size time steps.

  17. GPU acceleration of time-domain fluorescence lifetime imaging

    NASA Astrophysics Data System (ADS)

    Wu, Gang; Nowotny, Thomas; Chen, Yu; Li, David Day-Uei

    2016-01-01

    Fluorescence lifetime imaging microscopy (FLIM) plays a significant role in biological sciences, chemistry, and medical research. We propose a graphic processing unit (GPU) based FLIM analysis tool suitable for high-speed, flexible time-domain FLIM applications. With a large number of parallel processors, GPUs can significantly speed up lifetime calculations compared to CPU-OpenMP (parallel computing with multiple CPU cores) based analysis. We demonstrate how to implement and optimize FLIM algorithms on GPUs for both iterative and noniterative FLIM analysis algorithms. The implemented algorithms have been tested on both synthesized and experimental FLIM data. The results show that at the same precision, the GPU analysis can be up to 24-fold faster than its CPU-OpenMP counterpart. This means that even for high-precision but time-consuming iterative FLIM algorithms, GPUs enable fast or even real-time analysis.

  18. Time-accurate Navier-Stokes calculations with multigrid acceleration

    NASA Technical Reports Server (NTRS)

    Melson, N. D.; Sanetrik, Mark D.; Atkins, Harold L.

    1993-01-01

    An efficient method for calculating unsteady flows is presented, with emphasis on a modified version of the thin-layer Navier-Stokes equations. Fourier stability analysis is used to illustrate the effect of treating the source term implicitly instead of explicity, as well as to illustrate other algorithmic choices. A 2D circular cylinder (with a Reynolds number of 1200 and a Mach number of 0.3) is calculated. The present scheme requires only about 10 percent of the computer time required by global minimum time stepping.

  19. Time dependent solution for acceleration of tau-leaping

    NASA Astrophysics Data System (ADS)

    Fu, Jin; Wu, Sheng; Petzold, Linda R.

    2013-02-01

    The tau-leaping method is often effective for speeding up discrete stochastic simulation of chemically reacting systems. However, when fast reactions are involved, the speed-up for this method can be quite limited. One way to address this is to apply a stochastic quasi-steady state assumption. However we must be careful when using this assumption. If the fast subsystem cannot reach a steady distribution fast enough, the quasi-steady-state assumption will propagate error into the simulation. To avoid these errors, we propose to use the time dependent solution rather than the quasi-steady-state. Generally speaking, the time dependent solution is not easy to derive for an arbitrary network. However, for some common motifs we do have time dependent solutions. We derive the time dependent solutions for these motifs, and then show how they can be used with tau-leaping to achieve substantial speed-ups, including for a realistic model of blood coagulation. Although the method is complicated, we have automated it.

  20. Time dependent solution for acceleration of tau-leaping

    SciTech Connect

    Fu, Jin; Wu, Sheng; Petzold, Linda R.

    2013-02-15

    The tau-leaping method is often effective for speeding up discrete stochastic simulation of chemically reacting systems. However, when fast reactions are involved, the speed-up for this method can be quite limited. One way to address this is to apply a stochastic quasi-steady state assumption. However we must be careful when using this assumption. If the fast subsystem cannot reach a steady distribution fast enough, the quasi-steady-state assumption will propagate error into the simulation. To avoid these errors, we propose to use the time dependent solution rather than the quasi-steady-state. Generally speaking, the time dependent solution is not easy to derive for an arbitrary network. However, for some common motifs we do have time dependent solutions. We derive the time dependent solutions for these motifs, and then show how they can be used with tau-leaping to achieve substantial speed-ups, including for a realistic model of blood coagulation. Although the method is complicated, we have automated it.

  1. Acceleration in a nonplanar time-dependent billiard

    NASA Astrophysics Data System (ADS)

    Raeisi, Sedighe; Eslami, Parvin

    2016-08-01

    We study the dynamical properties of a particle in a nonplanar square billiard. The plane of the billiard has a sinusoidal shape. We consider both the static and time-dependent plane. We study the affect of different parameters that control the geometry of the billiard in this model. We consider variations of different parameters of the model and describe how the particle trajectory is affected by these parameters. We also investigate the dynamical behavior of the system in the static condition using its reduced phase plot and show that the dynamics of the particle inside the billiard may be regular, mixed, or chaotic. Finally, the problem of the particle energy growth is studied in the billiard with the time-dependent plane. We show that when in the static case, the billiard is chaotic, then the particle energy in the time-dependent billiard grows for a small number of collisions, and then it starts to saturate. But when the dynamics of the static case is regular, then the particle average energy in the time-dependent situation stays constant.

  2. Acceleration in a nonplanar time-dependent billiard.

    PubMed

    Raeisi, Sedighe; Eslami, Parvin

    2016-08-01

    We study the dynamical properties of a particle in a nonplanar square billiard. The plane of the billiard has a sinusoidal shape. We consider both the static and time-dependent plane. We study the affect of different parameters that control the geometry of the billiard in this model. We consider variations of different parameters of the model and describe how the particle trajectory is affected by these parameters. We also investigate the dynamical behavior of the system in the static condition using its reduced phase plot and show that the dynamics of the particle inside the billiard may be regular, mixed, or chaotic. Finally, the problem of the particle energy growth is studied in the billiard with the time-dependent plane. We show that when in the static case, the billiard is chaotic, then the particle energy in the time-dependent billiard grows for a small number of collisions, and then it starts to saturate. But when the dynamics of the static case is regular, then the particle average energy in the time-dependent situation stays constant. PMID:27627308

  3. Framing Health Messages for Adolescents: Should We Use Objective Time Periods, Temporal Benchmarks, or Both?

    ERIC Educational Resources Information Center

    McKay, Michael T.; Cole, Jon C.; Sumnall, Harry R.; Goudie, Andrew J.

    2012-01-01

    Time perspective is a cognitive-motivational construct, which has been shown to be related to decision-making, motivation and adjustment. The majority of research into time perspective has been conducted in college students and/or general population samples. Focus groups were held as part of a larger investigation into the relationship between…

  4. Accelerating Real-Time String Searching with Multicore Processors

    SciTech Connect

    Villa, Oreste; Scarpazza, Daniele P.; Petrini, Fabrizio

    2008-04-01

    String searching is at the core of tools used to search, filter, and protect data, but this has become increasingly difficult to do in real time as communication speed grows. The authors present an optimization strategy for a popular algorithm that fully exploits the IBM Cell Broadband Engine architecture to perform exact string matching against large dictionaries and also offer various solutions to alleviate memory congestion.

  5. Multihit two-dimensional charged-particle imaging system with real-time image processing at 1000 frames/s

    NASA Astrophysics Data System (ADS)

    Horio, Takuya; Suzuki, Toshinori

    2009-01-01

    A high-speed imaging system developed for two-dimensional counting of charged particles is presented. Microchannel plates coupled with a phosphor screen of a short emission lifetime (<1 μs) are used to visualize the two-dimensional positions of charged-particle impacts, and the image on the phosphor screen is captured with a 1 kHz complementary metal oxide semiconductor (CMOS) image sensor (512×512 pixels). A multistage image intensifier consisting of the first and second generation devices was used to compensate for the low sensitivity of CMOS. The centers of gravity (COG) of individual light spots in each image frame are calculated in real time by a field programmable gate array circuit. The performance of this system is tested by time-resolved photoelectron imaging (TR-PEI) of NO using (1+1') resonance enhanced multiphoton ionization via the A Σ2+ state with a femtosecond laser operated at 1 kHz. The new system enabled COG detection for more than ten particles in each frame at 1 kHz and achieved an extremely high degree of accuracy in the measurement of photoelectron angular distributions in TR-PEI.

  6. The operant reserve: a computer simulation in (accelerated) real time.

    PubMed

    Catania, A Charles

    2005-05-31

    In Skinner's Reflex Reserve theory, reinforced responses added to a reserve depleted by responding. It could not handle the finding that partial reinforcement generated more responding than continuous reinforcement, but it would have worked if its growth had depended not just on the last response but also on earlier responses preceding a reinforcer, each weighted by delay. In that case, partial reinforcement generates steady states in which reserve decrements produced by responding balance increments produced when reinforcers follow responding. A computer simulation arranged schedules for responses produced with probabilities proportional to reserve size. Each response subtracted a fixed amount from the reserve and added an amount weighted by the reciprocal of the time to the next reinforcer. Simulated cumulative records and quantitative data for extinction, random-ratio, random-interval, and other schedules were consistent with those of real performances, including some effects of history. The model also simulated rapid performance transitions with changed contingencies that did not depend on molar variables or on differential reinforcement of inter-response times. The simulation can be extended to inhomogeneous contingencies by way of continua of reserves arrayed along response and time dimensions, and to concurrent performances and stimulus control by way of different reserves created for different response classes. PMID:15845312

  7. The operant reserve: a computer simulation in (accelerated) real time.

    PubMed

    Catania, A Charles

    2005-05-31

    In Skinner's Reflex Reserve theory, reinforced responses added to a reserve depleted by responding. It could not handle the finding that partial reinforcement generated more responding than continuous reinforcement, but it would have worked if its growth had depended not just on the last response but also on earlier responses preceding a reinforcer, each weighted by delay. In that case, partial reinforcement generates steady states in which reserve decrements produced by responding balance increments produced when reinforcers follow responding. A computer simulation arranged schedules for responses produced with probabilities proportional to reserve size. Each response subtracted a fixed amount from the reserve and added an amount weighted by the reciprocal of the time to the next reinforcer. Simulated cumulative records and quantitative data for extinction, random-ratio, random-interval, and other schedules were consistent with those of real performances, including some effects of history. The model also simulated rapid performance transitions with changed contingencies that did not depend on molar variables or on differential reinforcement of inter-response times. The simulation can be extended to inhomogeneous contingencies by way of continua of reserves arrayed along response and time dimensions, and to concurrent performances and stimulus control by way of different reserves created for different response classes.

  8. Methods for Expanding Rotary Wing Aircraft Health and Usage Monitoring Systems to the Rotating Frame through Real-time Rotor Blade Kinematics Estimation

    NASA Astrophysics Data System (ADS)

    Allred, Charles Jefferson

    mechanism, similar to a Stewart Platform. A calibration method for this device is developed and the improved orientation estimation results are shown. The second method is not specific to the fully articulated rotor head mounting geometry of the first method. Rather, it utilizes micro-electromechanical (MEMS) accelerometers and gyroscopes configured to measure the centrifugal acceleration and rotation rate induced through rotor head rotation differentially. By measuring these quantities differentially, other accelerations from the fuselage reference frame are removed from the measurement, resulting in acceleration and rate quantities that are impacted only by the angle of the sensors relative to the plane of rotation. By mounting these sensors strategically and symmetrically about the rotor blade root center of rotation, the orientation of the rotor blade can be estimated in real time.

  9. Egocentric and allocentric reference frames for catching a falling object.

    PubMed

    Le Séac'h, Anne Brec'hed; Senot, Patrice; McIntyre, Joseph

    2010-04-01

    When programming movement, one must account for gravitational acceleration. This is particularly important when catching a falling object because the task requires a precise estimate of time-to-contact. Knowledge of gravity's effects is intimately linked to our definition of 'up' and 'down'. Both directions can be described in an allocentric reference frame, based on visual and/or gravitational cues, or in an egocentric reference frame in which the body axis is taken as vertical. To test which frame humans use to predict gravity's effect, we asked participants to intercept virtual balls approaching from above or below with artificially controlled acceleration that could be congruent or not with gravity. To dissociate between these frames, subjects were seated upright (trunk parallel to gravity) or lying down (body axis orthogonal to the gravitational axis). We report data in line with the use of an allocentric reference frame and discuss its relevance depending on available gravity-related cues. PMID:20024651

  10. "simplest Molecule" Clarifies Modern Physics I. Cw Laser Space-Time Frame Dynamics

    NASA Astrophysics Data System (ADS)

    Reimer, T. C.; Harter, W. G.

    2014-06-01

    Molecular spectroscopy makes very precise applications of quantum theory including GPS, BEC, and laser clocks. Now it can return the favor by shedding some light on modern physics mysteries by further unifying quantum theory and relativity. * We first ask, "What is the simplest molecule?" Hydrogen H2 is the simplest, stable molecule. Positronium is an electron-positron (e+e-)-pair. An even simpler "molecule" or "radical" is a photon-pair (γ, γ) that under certain conditions can create an (e+e-)-pair. * To help unravel relativistic and quantum mysteries consider CW laser beam pairs or TE-waveguides. Remarkably, their wave interference immediately gives Minkowski space-time coordinates and clearly relates eight kinds of space-time wave dilations or contractions to shifts in Doppler frequency or wavenumber. * Modern physics students may find this approach significantly simplifies and clarifies relativistic physics in space-time (x,ct) and inverse time-space (ω,ck). It resolves some mysteries surrounding super-constant c=299,792,458m/s by proving "Evenson's Axiom" named in honor of NIST metrologist Ken Evenson (1932-2002) whose spectroscopy established c to start a precision-renaissance in spectroscopy and GPS metrology. * The following Talk II applies this approach to relativistic quantum mechanics.

  11. ``Simplest Molecule'' Clarifies Modern Physics I. CW Laser Space-Time Frame Dynamics

    NASA Astrophysics Data System (ADS)

    Reimer, Tyle; Harter, William

    2015-05-01

    Molecular spectroscopy makes very precise applications of quantum theory including GPS, BEC, and laser clocks. Now it can return the favor by shedding some light on modern physics mysteries by further unifying quantum theory and relativity. We first ask, ``What is the simplest molecule?'' Hydrogen H2 is the simplest stable molecule. Positronium is an electron-positron (e+e-) -pair. An even simpler ``molecule'' or ``radical'' is a photon-pair (γ, γ) that under certain conditions can create an (e+e-) -pair. To help unravel relativistic and quantum mysteries consider CW laser beam pairs or TE-waveguides. Remarkably, their wave interference immediately gives Minkowski space-time coordinates and clearly relates eight kinds of space-time wave dilations or contractions to shifts in Doppler frequency or wavenumber. Modern physics students may find this approach significantly simplifies and clarifies relativistic physics in space-time (x,ct) and inverse time-space (ω,ck). It resolves some mysteries surrounding super-constant c = 299,792,458 m/s by proving ``Evenson's Axiom'' named in honor of NIST metrologist Ken Evenson (1932-2002) whose spectroscopy established c to start a precision renaissance in spectroscopy and GPS metrology.

  12. Molecular evidence from the nuclear genome for the time frame of human evolution.

    PubMed

    Easteal, S; Herbert, G

    1997-01-01

    Evolutionary divergence times can be inferred from molecular distances if a molecular clock can be assumed and if the substitution rate can be estimated. We present new evidence from relative rate tests that the rate of substitution at fourfold degenerate sites of nuclear genome-coding DNA is uniform in primate and rodent lineages. We also review recent relative rate test results showing substitution rate uniformity in the nuclear genome of simian primates. DNA distances between a range of mammalian taxa shows that a molecular clock is inconsistent with many assumed divergence times irrespective of the assumed substitution rate. We find that the substitution rate that implies the best compromise fit with divergence times across the range of taxa is 2.0-2.25 x 10(-9). This range of substitution rates implies a divergence time of humans and chimpanzees of 4.0-3.6 million years ago. This postdates the occurrence of Ardipithecus ramidus and the earliest occurrence of Australopithecus afarensis, suggesting that the common ancestor of humans and chimpanzees was bipedal and that the trait has been lost in chimpanzees rather than gained in humans.

  13. Student Understanding of Time in Special Relativity: Simultaneity and Reference Frames.

    ERIC Educational Resources Information Center

    Scherr, Rachel E.; Shaffer, Peter S.; Vokos, Stamatis

    2001-01-01

    Reports on an investigation of students' understanding of the concept of time in special relativity. Discusses a series of research tasks to illustrate how student reasoning of fundamental concepts of relativity was probed. Indicates that after standard instruction, students have serious difficulties with the relativity of simultaneity and the…

  14. Time-Dependent Selection of an Optimal Set of Sources to Define a Stable Celestial Reference Frame

    NASA Technical Reports Server (NTRS)

    Le Bail, Karine; Gordon, David

    2010-01-01

    Temporal statistical position stability is required for VLBI sources to define a stable Celestial Reference Frame (CRF) and has been studied in many recent papers. This study analyzes the sources from the latest realization of the International Celestial Reference Frame (ICRF2) with the Allan variance, in addition to taking into account the apparent linear motions of the sources. Focusing on the 295 defining sources shows how they are a good compromise of different criteria, such as statistical stability and sky distribution, as well as having a sufficient number of sources, despite the fact that the most stable sources of the entire ICRF2 are mostly in the Northern Hemisphere. Nevertheless, the selection of a stable set is not unique: studying different solutions (GSF005a and AUG24 from GSFC and OPA from the Paris Observatory) over different time periods (1989.5 to 2009.5 and 1999.5 to 2009.5) leads to selections that can differ in up to 20% of the sources. Observing, recording, and network improvement are some of the causes, showing better stability for the CRF over the last decade than the last twenty years. But this may also be explained by the assumption of stationarity that is not necessarily right for some sources.

  15. An assessment of the government liquid hydrogen requirements for the 1995-2005 time frame

    NASA Technical Reports Server (NTRS)

    Bain, Addison

    1990-01-01

    The results of government study of long range liquid hydrogen (LH2) requirements for the time period of 1995 through the year 2005 are presented. To assure an adequate supply of LH2 is available in support of various programs, it is imperative a long range projection of LH2 requirements be developed and maintained. This information is vital in planning for necessary procurement actions and assuring adequate industry lead time to acquiring the necessary production and distribution capabilities. The Advanced Launch System and High-Altitude Long-Endurance programs may represent the predominant government needs for LH2 in the long range. The assembled data clearly indicates a need for KSC (Kennedy Space Center) constant program/project surveillance. Also clear is the need for KSC to monitor industry's plans for LH2 plant production and distribution expansion.

  16. Characteristics of Four SPE Classes According to Onset Timing and Proton Acceleration Patterns

    NASA Astrophysics Data System (ADS)

    Kim, Roksoon

    2015-04-01

    In our previous work (Kim et al., 2015), we suggested a new classification scheme, which categorizes the SPEs into four groups based on association with flare or CME inferred from onset timings as well as proton acceleration patterns using multienergy observations. In this study, we have tried to find whether there are any typical characteristics of associated events and acceleration sites in each group using 42 SPEs from 1997 to 2012. We find: (i) if the proton acceleration starts from a lower energy, a SPE has a higher chance to be a strong event (> 5000 pfu) even if the associated flare and CME are not so strong. The only difference between the SPEs associated with flare and CME is the location of the acceleration site. For the former, the sites are very low ( ~1 Rs) and close to the western limb, while the latter has a relatively higher (mean=6.05 Rs) and wider acceleration sites. (ii) When the proton acceleration starts from the higher energy, a SPE tends to be a relatively weak event (< 1000 pfu), in spite of its associated CME is relatively stronger than previous group. (iii) The SPEs categorized by the simultaneous proton acceleration in whole energy range within 10 minutes, tend to show the weakest proton flux (mean=327 pfu) in spite of strong related eruptions. Their acceleration heights are very close to the locations of type II radio bursts. Based on those results, we suggest that the different characteristics of the four groups are mainly due to the different mechanisms governing the acceleration pattern and interval, and different condition such as the acceleration location.

  17. Stopping time: Henry Fox Talbot and the origins of freeze-frame photography.

    PubMed

    Ramalingam, Chitra

    2008-09-01

    As an image-making tool for scientists studying the transient, instantaneous photography has long been seen as opening up a visual realm previously inaccessible to the inferior testimony of the human eye. But when photographic pioneer Henry Fox Talbot took the first photograph of a moving object by the light of an electric spark in 1851, he was guided by existing visual practices designed to create instantaneous vision in the eye itself. Exploring the background behind the peculiar subject of his experiment - a mechanically spinning disc - reveals a hidden prehistory of spark-illuminated photography: physicists' pre-photographic techniques for stopping time.

  18. Nonlinear finite element model updating of an infilled frame based on identified time-varying modal parameters during an earthquake

    NASA Astrophysics Data System (ADS)

    Asgarieh, Eliyar; Moaveni, Babak; Stavridis, Andreas

    2014-11-01

    A model updating methodology is proposed for calibration of nonlinear finite element (FE) models simulating the behavior of real-world complex civil structures subjected to seismic excitations. In the proposed methodology, parameters of hysteretic material models assigned to elements (or substructures) of a nonlinear FE model are updated by minimizing an objective function. The objective function used in this study is the misfit between the experimentally identified time-varying modal parameters of the structure and those of the FE model at selected time instances along the response time history. The time-varying modal parameters are estimated using the deterministic-stochastic subspace identification method which is an input-output system identification approach. The performance of the proposed updating method is evaluated through numerical and experimental applications on a large-scale three-story reinforced concrete frame with masonry infills. The test structure was subjected to seismic base excitations of increasing amplitude at a large outdoor shake-table. A nonlinear FE model of the test structure has been calibrated to match the time-varying modal parameters of the test structure identified from measured data during a seismic base excitation. The accuracy of the proposed nonlinear FE model updating procedure is quantified in numerical and experimental applications using different error metrics. The calibrated models predict the exact simulated response very accurately in the numerical application, while the updated models match the measured response reasonably well in the experimental application.

  19. Solar/hydrogen systems assessment. Volume 1: Solar/hydrogen systems for the 1985 - 2000 time frame

    NASA Technical Reports Server (NTRS)

    Foster, R. W.; Tison, R. R.; Escher, W. J. D.; Hanson, J. A.

    1980-01-01

    Opportunities for commercialization of systems capable of producing hydrogen from solar energy were studied. The hydrogen product costs that might be achieved by the four selected candidate systems was compared with the pricing structure and practices of the commodity gas market. Subsequently, product cost and market price match was noted to exist in the small user sector of the hydrogen marketplace. Barriers to and historical time lags in, commercialization of new technologies are reviewed. Recommendations for development and demonstration programs designed to accelerate the commercialization of the candidate systems are presented.

  20. A look at global seismicity during 1999 in the longer-term time frame

    NASA Astrophysics Data System (ADS)

    Marza, Vasile; Carvalho, Juraci; Barros, Lucas; Chimpliganond, Cristiano

    An analysis and discussion of the main features and effects of the 1999global seismicity based especially on the inferred patterns of strong(Mw 7) earthquakes using NEIC/USGS data is presented.Based on the above data and their statistical features (see also Table 1)one may state that from the point of view of occurrence rate (number/yr)the 1999 global seismicity was fairly regular, but from the moment (orenergy) release standpoint it is well under the long-term average. The spacepartition was again rather typical and time distribution was quasi-Poissonian,noteworthy, the 1999 worldwide seismicity had an anomalously high deathtoll, to be discussed later. Two main new insights are brought by ouranalysis: (i) a (mega)quiescence along the whole south American segmentof circum-Pacific earthquake belt, which was inferred and rated asanomalous while it was underway and which, in retrospect, ended with thegreat (Mw = 8.4 HRV) 2001 Arequipa (Peru) event; (ii) an intriguingmonotonous rate decrease within only magnitude class 5.0 to 5.9 duringthe analyzed period (i.e., 1990-1999).

  1. The 2-MEV model: Constancy of adolescent environmental values within an 8-year time frame

    NASA Astrophysics Data System (ADS)

    Bogner, F. X.; Johnson, B.; Buxner, S.; Felix, L.

    2015-08-01

    The 2-MEV model is a widely used tool to monitor children's environmental perception by scoring individual values. Although the scale's validity has been confirmed repeatedly and independently as well as the scale is in usage within more than two dozen language units all over the world, longitudinal properties still need clarification. The purpose of the present study therefore was to validate the 2-MEV scale based on a large data basis of 10,676 children collected over an eight-year period. Cohorts of three different US states contributed to the sample by responding to a paper-and-pencil questionnaire within their pre-test initiatives in the context of field center programs. Since we used only the pre-program 2-MEV scale results (which is before participation in education programs), the data were clearly unspoiled by any follow-up interventions. The purpose of analysis was fourfold: First, to test and confirm the hypothesized factorized structure for the large data set and for the subsample of each of the three states. Second, to analyze the scoring pattern across the eight years' time range for both preservation and utilitarian preferences. Third, to investigate any age effects in the extracted factors. Finally, to extract suitable recommendations for educational implementation efforts.

  2. Perceptual frames in frequency estimation.

    PubMed

    Zyłowska, Aleksandra; Kossek, Marcin; Wawrzyniak, Małgorzata

    2014-02-01

    This study is an introductory investigation of cognitive frames, focused on perceptual frames divided into information and formal perceptual frames, which were studied based on sub-additivity of frequency estimations. It was postulated that different presentations of a response scale would result in different percentage estimates of time spent watching TV or using the Internet. The results supported the existence of perceptual frames that influence the perception process and indicated that information perceptual frames had a stronger effect than formal frames. The measures made possible the exploration of the operation of perceptual frames and also outlined the relations between heuristics and cognitive frames. PMID:24765715

  3. Evaluation of highly accelerated real-time cardiac cine MRI in tachycardia.

    PubMed

    Bassett, Elwin C; Kholmovski, Eugene G; Wilson, Brent D; DiBella, Edward V R; Dosdall, Derek J; Ranjan, Ravi; McGann, Christopher J; Kim, Daniel

    2014-02-01

    Electrocardiogram (ECG)-gated breath-hold cine MRI is considered to be the gold standard test for the assessment of cardiac function. However, it may fail in patients with arrhythmia, impaired breath-hold capacity and poor ECG gating. Although ungated real-time cine MRI may mitigate these problems, commercially available real-time cine MRI pulse sequences using parallel imaging typically yield relatively poor spatiotemporal resolution because of their low image acquisition efficiency. As an extension of our previous work, the purpose of this study was to evaluate the diagnostic quality and accuracy of eight-fold-accelerated real-time cine MRI with compressed sensing (CS) for the quantification of cardiac function in tachycardia, where it is challenging for real-time cine MRI to provide sufficient spatiotemporal resolution. We evaluated the performances of eight-fold-accelerated cine MRI with CS, three-fold-accelerated real-time cine MRI with temporal generalized autocalibrating partially parallel acquisitions (TGRAPPA) and ECG-gated breath-hold cine MRI in 21 large animals with tachycardia (mean heart rate, 104 beats per minute) at 3T. For each cine MRI method, two expert readers evaluated the diagnostic quality in four categories (image quality, temporal fidelity of wall motion, artifacts and apparent noise) using a Likert scale (1-5, worst to best). One reader evaluated the left ventricular functional parameters. The diagnostic quality scores were significantly different between the three cine pulse sequences, except for the artifact level between CS and TGRAPPA real-time cine MRI. Both ECG-gated breath-hold cine MRI and eight-fold accelerated real-time cine MRI yielded all four scores of ≥ 3.0 (acceptable), whereas three-fold-accelerated real-time cine MRI yielded all scores below 3.0, except for artifact (3.0). The left ventricular ejection fraction (LVEF) measurements agreed better between ECG-gated cine MRI and eight-fold-accelerated real-time cine MRI

  4. A magnetostratigraphic time frame for Plio-Pleistocene transgressions in the South Caspian Basin, Azerbaijan

    NASA Astrophysics Data System (ADS)

    Van Baak, C. G. C.; Vasiliev, I.; Stoica, M.; Kuiper, K. F.; Forte, A. M.; Aliyeva, E.; Krijgsman, W.

    2013-04-01

    The isolation of the Caspian Sea took place in the latest Miocene coinciding with a significant lowering of sea level and the deposition of a massive lowstand deltaic system. This so-called Productive Series is the main reservoir unit of the South Caspian oil-province. The Productive Series is overlain by marine clays from the Akchagylian and Apsheronian regional stages. During the Plio-Pleistocene, the Caspian basin experienced several short periods of intermittent connectivity with other marine basins. This work aims to create integrated, high-resolution, bio-magnetostratigraphic dating of these regional transgressions in key sections of the South Caspian Basin in Azerbaijan. We sample two long sections, the Lokbatan section in the Palaeo-Volga delta and the Xocashen section in the Kura Basin. Palaeoenvironmental reconstructions are derived from characteristic ostracod species. Rock magnetic analyses combined with thermal demagnetisation data indicate that the magnetic signal is carried dominantly by the iron oxide magnetite in the Productive Series of Lokbatan section and in the Xocashen section. The marine Akchagylian and Apsheronian of Lokbatan are characterised by the iron sulphide greigite, which appears to be of (near-) primary origin. The most logical correlation of the magnetic polarity patterns to the Geomagnetic Polarity Time Scale dates the Akchagylian transgression at ~ 3.2 Ma, a major transgression during the Apsheronian at ~ 2.0 Ma and the Bakunian transgression at 0.85-0.89 Ma. Ostracod assemblages indicate increasing salinities during these transgressions, from fresh water lacustrine to brackish-marine species. This implies that marine connections have been created with an adjacent basin that has a higher salinity, most likely the Black Sea.

  5. On Spin-Statistics and Bogoliubov Transformations in Flat Space-Time with Acceleration Conditions

    NASA Astrophysics Data System (ADS)

    Good, Michael R. R.

    2013-01-01

    A single real scalar field of spin zero obeying the Klein-Gordon equation in flat space-time under external conditions is considered in the context of the spin-statistics connection. An imposed accelerated boundary on the field is made to become, in the far future, (1) asymptotically inertial and (2) asymptotically noninertial (with an infinite acceleration). The constant acceleration Unruh effect is also considered. The systems involving nontrivial Bogoliubov transformations contain dynamics which point to commutation relations. Particles described by in-modes obey the same statistics as particles described by out-modes. It is found in the nontrivial systems that the spin-statistics connection can be manifest from the acceleration. The equation of motion for the boundary which forever emits thermal radiation is revealed.

  6. Moving Forward in Space and Time: How Strong is the Conceptual Link between Spatial and Temporal Frames of Reference?

    PubMed Central

    Bender, Andrea; Rothe-Wulf, Annelie; Hüther, Lisa; Beller, Sieghard

    2012-01-01

    People often use spatial vocabulary to describe temporal relations, and this increasingly has motivated attempts to map spatial frames of reference (FoRs) onto time. Recent research suggested that speech communities, which differ in how they conceptualize space, may also differ in how they conceptualize time and, more specifically, that the preferences for spatial FoRs should carry over to the domain of time. Here, we scrutinize this assumption (a) by reviewing data from recent studies on temporal references, (b) by comparing data we had collected in previous studies on preferences for spatial and temporal FoRs in four languages, (c) by analyzing new data from dynamic spatial tasks that resemble the temporal tasks more closely, and (d) by assessing the co-variation of individual preferences of English speakers across space and time. While the first set of data paints a mixed picture, the latter three do not support the assumption of a close link between referencing preferences across domains. We explore possible reasons for this lack of consistency and discuss implications for research on temporal references. PMID:23162519

  7. Highly accelerated real-time cardiac cine MRI using k-t SPARSE-SENSE.

    PubMed

    Feng, Li; Srichai, Monvadi B; Lim, Ruth P; Harrison, Alexis; King, Wilson; Adluru, Ganesh; Dibella, Edward V R; Sodickson, Daniel K; Otazo, Ricardo; Kim, Daniel

    2013-07-01

    For patients with impaired breath-hold capacity and/or arrhythmias, real-time cine MRI may be more clinically useful than breath-hold cine MRI. However, commercially available real-time cine MRI methods using parallel imaging typically yield relatively poor spatio-temporal resolution due to their low image acquisition speed. We sought to achieve relatively high spatial resolution (∼2.5 × 2.5 mm(2)) and temporal resolution (∼40 ms), to produce high-quality real-time cine MR images that could be applied clinically for wall motion assessment and measurement of left ventricular function. In this work, we present an eightfold accelerated real-time cardiac cine MRI pulse sequence using a combination of compressed sensing and parallel imaging (k-t SPARSE-SENSE). Compared with reference, breath-hold cine MRI, our eightfold accelerated real-time cine MRI produced significantly worse qualitative grades (1-5 scale), but its image quality and temporal fidelity scores were above 3.0 (adequate) and artifacts and noise scores were below 3.0 (moderate), suggesting that acceptable diagnostic image quality can be achieved. Additionally, both eightfold accelerated real-time cine and breath-hold cine MRI yielded comparable left ventricular function measurements, with coefficient of variation <10% for left ventricular volumes. Our proposed eightfold accelerated real-time cine MRI with k-t SPARSE-SENSE is a promising modality for rapid imaging of myocardial function.

  8. Mini acceleration and deceleration driving strategy to increase the operational time of flywheel hybrid module

    NASA Astrophysics Data System (ADS)

    Manaf, Muhammad Zaidan Abdul; Fakeruddin, Shafarul Hafidi; Zakaria, Mohamad Shukri; Saadun, Mohd Noor Asril; Hanafi, Mohd Hafidzal Mohd

    2015-05-01

    This paper presents a new driving strategy to increase the operational time of flywheel hybrid module. The flywheel hybrid module contains low cost mechanical parts which installed on the small motorcycle. Based on normal driving cycles characteristics, the Mini-AD driving strategy is develop. It is involved a series of short or mini acceleration cycle and short deceleration cycle on top of the normal driving cycles. The new strategy is simulated for flywheel hybrid module, aimed for acceleration phase only. Simulations show that the new driving strategy can increase the operational time of flywheel hybrid module up to 62.5%.

  9. Taming the escape dynamics of nonadiabatic time-periodically driven quantum dissipative system within the frame of Wigner formalism

    NASA Astrophysics Data System (ADS)

    Shit, Anindita; Chattopadhyay, Sudip; Ray Chaudhuri, Jyotipratim

    2014-03-01

    Escape under the action of the external modulation constitutes a nontrivial generalization of an conventional Kramers rate because the system is away from thermal equilibrium. A derivation of this result from the point of view of Langevin dynamics in the frame of Floquet theorem in conjunction with the Kapitza-Landau time window (that leads to an attractive description of the time-dependent quantum dynamics in terms of time-independent one) has been provided. The quantum escape rate in the intermediate-to-high and very-high damping regime so obtained analytically using the phase space formalism associated with the Wigner distribution and path-integral formalism bears a quantum correction that depends strongly on the barrier height. It is shown that an increase of (amplitude/frequency) ratio causes the system to decay faster, in general. The crossover temperature between tunneling and thermal activation increases in the presence of field so that quantum effects in the escape are relevant at higher temperatures.

  10. Choice reaction time to movement of eccentric visual targets during concurrent rotary acceleration

    NASA Technical Reports Server (NTRS)

    Hamerman, J. A.

    1979-01-01

    This study investigates the influence of concurrent rotary acceleration on choice reaction time (RT) to a small, accelerating visual cursor on a cathode-ray tube. Subjects sat in an enclosed rotating device at the center of rotation and observed a 3-mm dot accelerating at different rates across a cathode-ray tube. The dot was viewed at various eccentricities under conditions of visual stimulation alone and with concurrent rotary acceleration. Subjects responded to both vertical and horizontal dot movements. There was a significant inverse relationship between choice RT and level of dot acceleration (p less than .001), and a significant direct relationship between choice RT and eccentricity (p less than .001). There was no significant difference between choice RT to vertical or horizontal dot motion (p greater than .25), and choice RT was not significantly affected by concurrent rotary acceleration (p greater than .10). The results are discussed in terms of the effects of vestibular stimulation on choice RT to visual motion.

  11. Acceleration of proliferative response of mouse fibroblasts by short-time pretreatment with polyphenols.

    PubMed

    Tsuruya, Makoto; Niwano, Yoshimi; Nakamura, Keisuke; Kanno, Taro; Nakashima, Takuji; Egusa, Hiroshi; Sasaki, Keiichi

    2014-11-01

    Under the hypothesis that photo-irradiated proanthocyanidin could accelerate wound healing through reactive oxygen species (ROS) formation, we examined the effect of proanthocyanidin on 3T3-L1 mouse fibroblasts with or without photo-irradiation. As a result, irrespective of presence or absence of photo-irradiation, only 1 min exposure of the cells to proanthocyanidin resulted in accelerated proliferation of the cells in a concentration-dependent manner. Similarly to proanthocyanidin, 1 min pretreatment with catechin, caffeic acid, and chlorogenic acid accelerated the proliferative response, but gallic acid, epicatechin gallate, epigallocatechin, and epigallocatechin gallate failed. If incorporated active ingredient such as proanthocyanidin for such a short time as 1 min accelerates the proliferation response, a bioassay was conducted by utilizing antioxidant potential of proanthocyanidin. That is, intracellular oxidation of 2',7'-dichlorodihydrofluorescin induced by H2O2 was significantly inhibited when the cells were pretreated with proanthocyanidin for 1 min, suggesting that incorporated proanthocyanidin into the cells exerted antioxidant effect. This was also supported by a liquid chromatography/mass spectrometry analysis in which incorporation of proanthocyanidin components such as catechin monomers and dimers into the cells within 1 min was confirmed. These results suggest that active polyphenolic compounds such as proanthocyanidin, catechin, caffeic acid, and chlorogenic acid incorporated into the cells in such a short time as 1 min could accelerate the proliferative response of the cells. PMID:25173673

  12. 3-Component acceleration field measurement by dual-time stereoscopic particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Perret, L.; Braud, P.; Fourment, C.; David, L.; Delville, J.

    2006-05-01

    In this article, a multiplane stereo-particle image velocimetry (PIV) system was implemented and validated to measure the three-component acceleration field in a plane of turbulent flows. The employed technique relies on the use of two stereoscopic particle image velocimetry (SPIV) systems to measure pairs of velocity fields superimposed in space but shifted in time. The time delay between the two velocity fields enables the implementation of a finite difference scheme to compute temporal derivatives. The use of two synchronized SPIV systems allows us to overcome the limited acquisition rate of PIV systems when dealing with highly turbulent flows. Moreover, a methodology based on the analysis of the spectral error distribution is described here to determine the optimal time delay to compute time derivatives. The present dual-time SPIV arrangement and the proposed analysis method are applied to measure three-component acceleration fields in a cross section of a subsonic plane turbulent mixing layer.

  13. Force-Time Characteristics and Running Velocity of Male Sprinters During the Acceleration Phase of Sprinting.

    ERIC Educational Resources Information Center

    Mero, Antti

    1988-01-01

    Investigation of the force-time characteristics of eight male sprinters during the acceleration phase of the sprint start suggested that the braking and propulsion phases occur immediately after the block phase and that muscle strength strongly affects running velocity in the sprint start. (Author/CB)

  14. The Gift of Time: Today's Academic Acceleration Case Study Voices of Experience

    ERIC Educational Resources Information Center

    Scheibel, Susan Riley

    2010-01-01

    The purpose of this qualitative case study was to examine today's academic acceleration from the lived experience and perspectives of two young adults whose education was shortened, thereby allowing them the gift of time. Through personal interviews, parent interviews, and physical artifacts, the researcher gained a complex, holistic understanding…

  15. Sensitivity Upgrades to the Idaho Accelerator Center Neutron Time of Flight Spectrometer

    SciTech Connect

    Thompson, S. J.; Kinlaw, M. T.; Harmon, J. F.; Wells, D. P.; Hunt, A. W.

    2007-10-26

    Past experiments have shown that discrimination between between fissionable and non-fissionable materials is possible using an interrogation technique that monitors for high energy prompt fission neutrons. Several recent upgrades have been made to the neutron time of flight spectrometer at the Idaho Accelerator Center with the intent of increasing neutron detection sensitivity, allowing for system use in nonproliferation and security applications.

  16. Finite-time position and velocity estimation adapted to noisy biased acceleration measurements from periodic motion

    NASA Astrophysics Data System (ADS)

    Estrada, Antonio; Efimov, Denis; Perruquetti, Wilfrid

    2016-09-01

    The present work focuses on the problem of velocity and position estimation. A solution is presented for a class of oscillating systems in which position, velocity and acceleration are zero mean signals. The proposed scheme considers that the dynamic model of the system is unknown. Only noisy acceleration measurements, that may be contaminated by zero mean noise and constant bias, are considered to be available. The proposal uses the periodic nature of the signals obtaining finite-time estimations while tackling integration drift accumulation.

  17. Using expert knowledge and modeling to define mangrove composition, functioning, and threats and estimate time frame for recovery.

    PubMed

    Mukherjee, Nibedita; Sutherland, William J; Khan, Md Nabiul I; Berger, Uta; Schmitz, Nele; Dahdouh-Guebas, Farid; Koedam, Nico

    2014-06-01

    Mangroves are threatened worldwide, and their loss or degradation could impact functioning of the ecosystem. Our aim was to investigate three aspects of mangroves at a global scale: (1) their constituents (2) their indispensable ecological functions, and (3) the maintenance of their constituents and functions in degraded mangroves. We focused on answering two questions: "What is a mangrove ecosystem" and "How vulnerable are mangrove ecosystems to different impacts"? We invited 106 mangrove experts globally to participate in a survey based on the Delphi technique and provide inputs on the three aspects. The outputs from the Delphi technique for the third aspect, i.e. maintenance of constituents and functions were incorporated in a modeling approach to simulate the time frame for recovery. Presented here for the first time are the consensus definition of the mangrove ecosystem and the list of mangrove plant species. In this study, experts considered even monospecific (tree) stands to be a mangrove ecosystem as long as there was adequate tidal exchange, propagule dispersal, and faunal interactions. We provide a ranking of the important ecological functions, faunal groups, and impacts on mangroves. Degradation due to development was identified as having the largest impact on mangroves globally in terms of spatial scale, intensity, and time needed for restoration. The results indicate that mangroves are ecologically unique even though they may be species poor (from the vegetation perspective). The consensus list of mangrove species and the ranking of the mangrove ecological functions could be a useful tool for restoration and management of mangroves. While there is ample literature on the destruction of mangroves due to aquaculture in the past decade, this study clearly shows that more attention must go to avoiding and mitigating mangrove loss due to coastal development (such as building of roads, ports, or harbors). PMID:25360265

  18. Using expert knowledge and modeling to define mangrove composition, functioning, and threats and estimate time frame for recovery.

    PubMed

    Mukherjee, Nibedita; Sutherland, William J; Khan, Md Nabiul I; Berger, Uta; Schmitz, Nele; Dahdouh-Guebas, Farid; Koedam, Nico

    2014-06-01

    Mangroves are threatened worldwide, and their loss or degradation could impact functioning of the ecosystem. Our aim was to investigate three aspects of mangroves at a global scale: (1) their constituents (2) their indispensable ecological functions, and (3) the maintenance of their constituents and functions in degraded mangroves. We focused on answering two questions: "What is a mangrove ecosystem" and "How vulnerable are mangrove ecosystems to different impacts"? We invited 106 mangrove experts globally to participate in a survey based on the Delphi technique and provide inputs on the three aspects. The outputs from the Delphi technique for the third aspect, i.e. maintenance of constituents and functions were incorporated in a modeling approach to simulate the time frame for recovery. Presented here for the first time are the consensus definition of the mangrove ecosystem and the list of mangrove plant species. In this study, experts considered even monospecific (tree) stands to be a mangrove ecosystem as long as there was adequate tidal exchange, propagule dispersal, and faunal interactions. We provide a ranking of the important ecological functions, faunal groups, and impacts on mangroves. Degradation due to development was identified as having the largest impact on mangroves globally in terms of spatial scale, intensity, and time needed for restoration. The results indicate that mangroves are ecologically unique even though they may be species poor (from the vegetation perspective). The consensus list of mangrove species and the ranking of the mangrove ecological functions could be a useful tool for restoration and management of mangroves. While there is ample literature on the destruction of mangroves due to aquaculture in the past decade, this study clearly shows that more attention must go to avoiding and mitigating mangrove loss due to coastal development (such as building of roads, ports, or harbors).

  19. Using expert knowledge and modeling to define mangrove composition, functioning, and threats and estimate time frame for recovery

    PubMed Central

    Mukherjee, Nibedita; Sutherland, William J; Khan, Md Nabiul I; Berger, Uta; Schmitz, Nele; Dahdouh-Guebas, Farid; Koedam, Nico

    2014-01-01

    Mangroves are threatened worldwide, and their loss or degradation could impact functioning of the ecosystem. Our aim was to investigate three aspects of mangroves at a global scale: (1) their constituents (2) their indispensable ecological functions, and (3) the maintenance of their constituents and functions in degraded mangroves. We focused on answering two questions: “What is a mangrove ecosystem” and “How vulnerable are mangrove ecosystems to different impacts”? We invited 106 mangrove experts globally to participate in a survey based on the Delphi technique and provide inputs on the three aspects. The outputs from the Delphi technique for the third aspect, i.e. maintenance of constituents and functions were incorporated in a modeling approach to simulate the time frame for recovery. Presented here for the first time are the consensus definition of the mangrove ecosystem and the list of mangrove plant species. In this study, experts considered even monospecific (tree) stands to be a mangrove ecosystem as long as there was adequate tidal exchange, propagule dispersal, and faunal interactions. We provide a ranking of the important ecological functions, faunal groups, and impacts on mangroves. Degradation due to development was identified as having the largest impact on mangroves globally in terms of spatial scale, intensity, and time needed for restoration. The results indicate that mangroves are ecologically unique even though they may be species poor (from the vegetation perspective). The consensus list of mangrove species and the ranking of the mangrove ecological functions could be a useful tool for restoration and management of mangroves. While there is ample literature on the destruction of mangroves due to aquaculture in the past decade, this study clearly shows that more attention must go to avoiding and mitigating mangrove loss due to coastal development (such as building of roads, ports, or harbors). PMID:25360265

  20. Impact of Interstellar Vehicle Acceleration and Cruise Velocity on Total Mission Mass and Trip Time

    NASA Technical Reports Server (NTRS)

    Frisbee, Robert H.

    2006-01-01

    Far-term interstellar missions, like their near-term solar system exploration counterparts, seek to minimize overall mission trip time and transportation system mass. Trip time is especially important in interstellar missions because of the enormous distances between stars and the finite limit of the speed of light (c). In this paper, we investigate the impact of vehicle acceleration and maximum or cruise velocity (Vcruise) on the total mission trip time. We also consider the impact that acceleration has on the transportation system mass (M) and power (P) (e.g., acceleration approx. power/mass and mass approx. power), as well as the impact that the cruise velocity has on the vehicle mass (e.g., the total mission change in velocity ((Delta)V) approx. Vcruise). For example, a Matter-Antimatter Annihilation Rocket's wet mass (Mwet) with propellant (Mp) will be a function of the dry mass of the vehicle (Mdry) and (Delta)V through the Rocket Equation. Similarly, a laser-driven LightSail's sail mass and laser power and mass will be a function of acceleration, Vcruise, and power-beaming distance (because of the need to focus the laser beam over interstellar distances).

  1. Accelerated multiscale space-time finite element simulation and application to high cycle fatigue life prediction

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Wen, Lihua; Naboulsi, Sam; Eason, Thomas; Vasudevan, Vijay K.; Qian, Dong

    2016-08-01

    A multiscale space-time finite element method based on time-discontinuous Galerkin and enrichment approach is presented in this work with a focus on improving the computational efficiencies for high cycle fatigue simulations. While the robustness of the TDG-based space-time method has been extensively demonstrated, a critical barrier for the extensive application is the large computational cost due to the additional temporal dimension and enrichment that are introduced. The present implementation focuses on two aspects: firstly, a preconditioned iterative solver is developed along with techniques for optimizing the matrix storage and operations. Secondly, parallel algorithms based on multi-core graphics processing unit are established to accelerate the progressive damage model implementation. It is shown that the computing time and memory from the accelerated space-time implementation scale with the number of degree of freedom N through ˜ O(N^{1.6}) and ˜ O(N), respectively. Finally, we demonstrate the accelerated space-time FEM simulation through benchmark problems.

  2. Unifying inflation with late-time acceleration by a BIonic system

    NASA Astrophysics Data System (ADS)

    Sepehri, Alireza; Rahaman, Farook; Setare, Mohammad Reza; Pradhan, Anirudh; Capozziello, Salvatore; Sardar, Iftikar Hossain

    2015-07-01

    We propose a cosmological model that unifies inflation, deceleration and acceleration phases of expansion history by a BIonic system. At the beginning, there are k black fundamental strings that transited to the BIon configuration at a given corresponding point. Here, two coupled universes, brane and antibrane, are created interacting each other through a wormhole and inflate. With decreasing temperature, the energy of this wormhole flows into the universe branes and leads to inflation. After a short time, the wormhole evaporates, the inflation ends and a deceleration epoch starts. By approaching the brane and antibrane universes together, a tachyon is born, grows and causes the creation of a new wormhole. At this time, the brane and antibrane universes result connected again and the late-time acceleration era of the universe begins. We compare our model with previous unified phantom models and observational data obtaining some cosmological parameters like temperature in terms of time. We also find that deceleration parameter is negative during inflation and late-time acceleration epochs, while it is positive during the deceleration era. This means that the model is consistent, in principle, with cosmological observations.

  3. Late time acceleration of the 3-space in a higher dimensional steady state universe in dilaton gravity

    SciTech Connect

    Akarsu, Özgür; Dereli, Tekin E-mail: tdereli@ku.edu.tr

    2013-02-01

    We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales.

  4. Improving linear accelerator service response with a real- time electronic event reporting system.

    PubMed

    Hoisak, Jeremy D P; Pawlicki, Todd; Kim, Gwe-Ya; Fletcher, Richard; Moore, Kevin L

    2014-09-08

    To track linear accelerator performance issues, an online event recording system was developed in-house for use by therapists and physicists to log the details of technical problems arising on our institution's four linear accelerators. In use since October 2010, the system was designed so that all clinical physicists would receive email notification when an event was logged. Starting in October 2012, we initiated a pilot project in collaboration with our linear accelerator vendor to explore a new model of service and support, in which event notifications were also sent electronically directly to dedicated engineers at the vendor's technical help desk, who then initiated a response to technical issues. Previously, technical issues were reported by telephone to the vendor's call center, which then disseminated information and coordinated a response with the Technical Support help desk and local service engineers. The purpose of this work was to investigate the improvements to clinical operations resulting from this new service model. The new and old service models were quantitatively compared by reviewing event logs and the oncology information system database in the nine months prior to and after initiation of the project. Here, we focus on events that resulted in an inoperative linear accelerator ("down" machine). Machine downtime, vendor response time, treatment cancellations, and event resolution were evaluated and compared over two equivalent time periods. In 389 clinical days, there were 119 machine-down events: 59 events before and 60 after introduction of the new model. In the new model, median time to service response decreased from 45 to 8 min, service engineer dispatch time decreased 44%, downtime per event decreased from 45 to 20 min, and treatment cancellations decreased 68%. The decreased vendor response time and reduced number of on-site visits by a service engineer resulted in decreased downtime and decreased patient treatment cancellations.

  5. Improving linear accelerator service response with a real- time electronic event reporting system.

    PubMed

    Hoisak, Jeremy D P; Pawlicki, Todd; Kim, Gwe-Ya; Fletcher, Richard; Moore, Kevin L

    2014-01-01

    To track linear accelerator performance issues, an online event recording system was developed in-house for use by therapists and physicists to log the details of technical problems arising on our institution's four linear accelerators. In use since October 2010, the system was designed so that all clinical physicists would receive email notification when an event was logged. Starting in October 2012, we initiated a pilot project in collaboration with our linear accelerator vendor to explore a new model of service and support, in which event notifications were also sent electronically directly to dedicated engineers at the vendor's technical help desk, who then initiated a response to technical issues. Previously, technical issues were reported by telephone to the vendor's call center, which then disseminated information and coordinated a response with the Technical Support help desk and local service engineers. The purpose of this work was to investigate the improvements to clinical operations resulting from this new service model. The new and old service models were quantitatively compared by reviewing event logs and the oncology information system database in the nine months prior to and after initiation of the project. Here, we focus on events that resulted in an inoperative linear accelerator ("down" machine). Machine downtime, vendor response time, treatment cancellations, and event resolution were evaluated and compared over two equivalent time periods. In 389 clinical days, there were 119 machine-down events: 59 events before and 60 after introduction of the new model. In the new model, median time to service response decreased from 45 to 8 min, service engineer dispatch time decreased 44%, downtime per event decreased from 45 to 20 min, and treatment cancellations decreased 68%. The decreased vendor response time and reduced number of on-site visits by a service engineer resulted in decreased downtime and decreased patient treatment cancellations. PMID

  6. Real-Time and Accelerated Solar Weathering of Commercial PV Modules: Preprint

    SciTech Connect

    Osterwald, C. R.; Pruett, J.; Myers, D. R.; Rummel, S.; Anderberg, A.; Ottoson, L.; Basso, T.

    2001-10-01

    Presented at the 2001 NCPV Program Review Meeting: We report the observed degradation in 6 different types of PV modules as a function of total UV exposure and give a number of recommendations for future weathering tests. Since 1997, using existing ASTM standards for weathering of materials, we have been conducting a solar weathering program on a group of six different types of photovoltaic (PV) modules. The methods used include real-time outdoor, accelerated outdoor, and accelerated indoor weathering. We have employed the technique specified in these standards that quantifies exposure totals by the time integral of the ultraviolet (UV) irradiance. In this paper, we report the observed degradation in the test modules as a function of total UV exposure, and give a number of recommendations for future weathering tests that resulted from our first attempt at a formal test program.

  7. Real-time and accelerated outdoor endurance testing of solar cells

    NASA Technical Reports Server (NTRS)

    Forestieri, A. F.; Anagnostou, E.

    1977-01-01

    Real-time and accelerated outdoor endurance testing was performed on a variety of samples of interest to the National Photovoltaic Conversion Program. The real-time tests were performed at seven different sites and the accelerated tests were performed at one of those sites in the southwestern United States. The purpose of the tests were to help evaluate the lifetime of photovoltaic systems. Three types of samples were tested; transmission samples of possible cover materials, sub-modules constructed using these materials attached to solar cells, and solar cell modules produced by the manufacturers for the ERDA program. Results indicate that suitable cover materials are glass, FEP-A and PFA. Dirt accumulation and cleanability are important factors in the selection of solar cell module covers and encapsulants.

  8. Using the Advanced Progressive Matrices (Set I) to Assess Fluid Ability in a Short Time Frame: An Item Response Theory-Based Analysis

    ERIC Educational Resources Information Center

    Chiesi, Francesca; Ciancaleoni, Matteo; Galli, Silvia; Primi, Caterina

    2012-01-01

    This article is aimed at evaluating the possibility that Set I of the Advanced Progressive Matrices (APM-Set I) can be employed to assess fluid ability in a short time frame. The APM-Set I was administered to a sample of 1,389 primary and secondary school students. Confirmatory factor analysis attested to the unidimensionality of the scale. Item…

  9. Real-time damage monitoring scheme in PSC girder bridge using output-only acceleration data

    NASA Astrophysics Data System (ADS)

    Kim, Jeong-Tae; Park, Jae-Hyung; Do, Han-Sung; Lee, Jung-Mi

    2007-04-01

    Artificial neural networks (ANNs) have been increasingly utilized for structural health monitoring (SHM) due to the advantage that it needs only a few training data to detect damage in structures. In this study, a new damage monitoring method using a set of parallel ANNs and acceleration signals is developed for alarming locations of damage in PSC girder bridges. First, theoretical backgrounds are described. The problem addressed in this paper is defined as the stochastic process. In addition, a parallel ANN-algorithm using output-only acceleration responses is newly designed for damage detection in real time. The cross-covariance of two acceleration-signals measured at two different locations is selected as the feature representing the structural condition. Neural networks are trained for potential loading patterns and damage scenarios of the target structure for which its actual loadings are unknown. The feasibility of the proposed method is evaluated from numerical model tests on PSC beams for which accelerations were acquired before and after several damage cases.

  10. A consistent approach for the treatment of Fermi acceleration in time-dependent billiards

    NASA Astrophysics Data System (ADS)

    Karlis, A. K.; Diakonos, F. K.; Constantoudis, V.

    2012-06-01

    The standard description of Fermi acceleration, developing in a class of time-dependent billiards, is given in terms of a diffusion process taking place in momentum space. Within this framework, the evolution of the probability density function (PDF) of the magnitude of particle velocities as a function of the number of collisions n is determined by the Fokker-Planck equation (FPE). In the literature, the FPE is constructed by identifying the transport coefficients with the ensemble averages of the change of the magnitude of particle velocity and its square in the course of one collision. Although this treatment leads to the correct solution after a sufficiently large number of collisions have been reached, the transient part of the evolution of the PDF is not described. Moreover, in the case of the Fermi-Ulam model (FUM), if a standard simplification is employed, the solution of the FPE is even inconsistent with the values of the transport coefficients used for its derivation. The goal of our work is to provide a self-consistent methodology for the treatment of Fermi acceleration in time-dependent billiards. The proposed approach obviates any assumptions for the continuity of the random process and the existence of the limits formally defining the transport coefficients of the FPE. Specifically, we suggest, instead of the calculation of ensemble averages, the derivation of the one-step transition probability function and the use of the Chapman-Kolmogorov forward equation. This approach is generic and can be applied to any time-dependent billiard for the treatment of Fermi-acceleration. As a first step, we apply this methodology to the FUM, being the archetype of time-dependent billiards to exhibit Fermi acceleration.

  11. Real time monitoring of accelerated chemical reactions by ultrasonication-assisted spray ionization mass spectrometry.

    PubMed

    Lin, Shu-Hsuan; Lo, Ta-Ju; Kuo, Fang-Yin; Chen, Yu-Chie

    2014-01-01

    Ultrasonication has been used to accelerate chemical reactions. It would be ideal if ultrasonication-assisted chemical reactions could be monitored by suitable detection tools such as mass spectrometry in real time. It would be helpful to clarify reaction intermediates/products and to have a better understanding of reaction mechanism. In this work, we developed a system for ultrasonication-assisted spray ionization mass spectrometry (UASI-MS) with an ~1.7 MHz ultrasonic transducer to monitor chemical reactions in real time. We demonstrated that simply depositing a sample solution on the MHz-based ultrasonic transducer, which was placed in front of the orifice of a mass spectrometer, the analyte signals can be readily detected by the mass spectrometer. Singly and multiply charged ions from small and large molecules, respectively, can be observed in the UASI mass spectra. Furthermore, the ultrasonic transducer used in the UASI setup accelerates the chemical reactions while being monitored via UASI-MS. The feasibility of using this approach for real-time acceleration/monitoring of chemical reactions was demonstrated. The reactions of Girard T reagent and hydroxylamine with steroids were used as the model reactions. Upon the deposition of reactant solutions on the ultrasonic transducer, the intermediate/product ions are readily generated and instantaneously monitored using MS within 1 s. Additionally, we also showed the possibility of using this reactive UASI-MS approach to assist the confirmation of trace steroids from complex urine samples by monitoring the generation of the product ions.

  12. Relativistic electron acceleration and decay time scales in the inner and outer radiation belts: SAMPEX

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Blake, J. B.; Callis, L. B.; Cummings, J. R.; Hovestadt, D.; Kanekal, S.; Klecker, B.; Mewaldt, R. A.; Zwickl, R. D.

    1994-01-01

    High-energy electrons have been measured systematically in a low-altitude (520 x 675 km), nearly polar (inclination = 82 deg) orbit by sensitive instruments onboard the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX). Count rate channels with electron energy thresholds ranging from 0.4 MeV to 3.5 MeV in three different instruments have been used to examine relativistic electron variations as a function of L-shell parameter and time. A long run of essentially continuous data (July 1992 - July 1993) shows substantial acceleration of energetic electrons throughout much of the magnetosphere on rapid time scales. This acceleration appears to be due to solar wind velocity enhancements and is surprisingly large in that the radiation belt 'slot' region often is filled temporarily and electron fluxes are strongly enhanced even at very low L-values (L aprroximately 2). A superposed epoch analysis shows that electron fluxes rise rapidly for 2.5 is approximately less than L is approximately less than 5. These increases occur on a time scale of order 1-2 days and are most abrupt for L-values near 3. The temporal decay rate of the fluxes is dependent on energy and L-value and may be described by J = Ke-t/to with t(sub o) approximately equals 5-10 days. Thus, these results suggest that the Earth's magnetosphere is a cosmic electron accelerator of substantial strength and efficiency.

  13. Solar/hydrogen systems for the 1985 to 2000 time frame. Volume I. Solar/hydrogen systems assessment. Final report

    SciTech Connect

    Foster, R. W.; Tison, R. R.; Escher, W. J.D.; Hanson, J. A.

    1980-06-01

    The findings of a study of opportunities for commercialization of systems capable of producing hydrogen from solar energy are presented in two volumes. A compendium of monographs by specialists in the fields of solar energy conversion technologies, hydrogen production technologies and related technology descriptions from the general literature comprise Volume II. This data base was used to support an evaluation and selection process that identified four candidate solar/hydrogen systems best suited to commercialization within the next two decades. Volume I first reviews the background of the work and the methods used. Then an evaluation of the hydrogen product costs that might be achieved by the four selected candidate systems (photovoltaic/water electrolysis, thermal-heat engine/water electrolysis, wind energy/water electrolysis, small hydrogen/water electrolysis) is compared with the pricing structure and practices of the commodity gas market. Subsequently, product cost and market price match is noted to exist in the small user sector of the hydrogen marketplace. Barriers to and historical time lags in, commercialization of new technologies are then reviewed. Finally, recommendations for development and demonstration programs designed to accelerate the commercialization of the candidate systems are presented.

  14. Effect of prolonged bedrest and plus Gz acceleration on peripheral visual response time

    NASA Technical Reports Server (NTRS)

    Haines, R. F.

    1973-01-01

    Peripheral visual response time changes during +G sub z acceleration following fourteen days of bedrest are considered as well as what effect prolonged bedrest has upon this response. Eighteen test lights, placed 10 deg are apart along the horizontal meridian of the subject's field of view, were presented in a random sequence. The subject was instructed to press a button as soon as a light appeared. Response time testing occurred periodically during bedrest and continuously during centrifugation testing. The results indicate that: (1) mean response time is significantly longer to stimuli imaged in the far periphery than to stimuli imaged closer to the line of sight; (2) mean response time at each stimulus position tends to be longer at plateau g than during the preacceleration baseline period; (3) mean response time tends to lengthen as the g level is increased; (4) peripheral visual response time during +G sub x acceleration at 2, 3.2, and 3.8 g was not a reliable advanced indicator that blackout was going to occur; and (5) the subject's field of view collapsed rapidly just before blackout. Bedrest data showed that the distribution of response times to stimuli imaged across the subject's horizontal retinal meridian remained remarkably constant from day to day during both the bedrest and recovery periods.

  15. Frames of Reference in the Classroom

    ERIC Educational Resources Information Center

    Grossman, Joshua

    2012-01-01

    The classic film "Frames of Reference" effectively illustrates concepts involved with inertial and non-inertial reference frames. In it, Donald G. Ivey and Patterson Hume use the cameras perspective to allow the viewer to see motion in reference frames translating with a constant velocity, translating while accelerating, and rotating--all with…

  16. Time-dependent modeling of solar wind acceleration from turbulent heating in open flux tubes

    NASA Astrophysics Data System (ADS)

    Woolsey, Lauren Nicole; Cranmer, Steven R.

    2015-04-01

    The acceleration of the solar wind, particularly from open flux tubes, remains an open question in solar physics. Countless physical processes have been suggested to explain all or parts of the coupled problem of coronal heating and wind acceleration, but the current generation of observations have been so far unable to distinguish which mechanism(s) dominates. In this project, we consider heating by Alfvén waves in a three-dimensional, time-dependent reduced magnetohydrodynamics model. This model solves for the heating rate as a function of time due to the twisting and braiding of magnetic field lines within a flux tube, which is caused by Alfvén waves generated at the single footpoint of the flux tube. We investigate three specific structures commonly found in the corona: 1) an open flux tube in a coronal hole, 2) an open flux tube on the edge of an equatorial streamer, and 3) an open flux tube directly neighboring an active region. We present the time-dependent heating rate, power spectra of fluctuations, and the time-averaged properties of the solar wind arising from each magnetic structure. We compare the time-averaged properties from the present modeling with previous results from a one-dimensional, time-steady code (Cranmer et al. 2007) to better calibrate the physics in the lower-dimensional code and get a better understanding of the intricate role that bursty, transient heating from Alfvén-wave-driven turbulence plays in the acceleration of the solar wind from different magnetic structures.

  17. Pseudo-entanglement evaluated in noninertial frames

    SciTech Connect

    Mehri-Dehnavi, Hossein; Mirza, Behrouz; Mohammadzadeh, Hosein; Rahimi, Robabeh

    2011-05-15

    Research Highlights: > We study pseudo-entanglement in noninertial frames. > We examine different measures of entanglement and nonclassical correlation for the state. > We find the threshold for entanglement is changed in noninertial frames. > We also describe the behavior of local unitary classes of states in noninertial frames. - Abstract: We study quantum discord, in addition to entanglement, of bipartite pseudo-entanglement in noninertial frames. It is shown that the entanglement degrades from its maximum value in a stationary frame to a minimum value in an infinite accelerating frame. There is a critical region found in which, for particular cases, entanglement of states vanishes for certain accelerations. The quantum discord of pseudo-entanglement decreases by increasing the acceleration. Also, for a physically inaccessible region, entanglement and nonclassical correlation are evaluated and shown to match the corresponding values of the physically accessible region for an infinite acceleration.

  18. Newton-Cartan Gravity in Noninertial Reference Frames

    NASA Astrophysics Data System (ADS)

    Rodriguez, Leo; St. Germaine-Fuller, James; Wickramasekara, Sujeev

    2015-03-01

    We study Newton-Cartan gravity under transformations into all noninertial, nonrelativistic reference frames. These transformations form an infinite dimensional Lie group, called the Galilean line group, which contains as a subgroup the Galilei group. The fictitious forces of noninertial reference frames are encoded in the Cartan connection transformed under the Galilean line group. These fictitious forces, which are coordinate effects, do not contribute to the Ricci tensor. Only the 00-component of the Ricci tensor is non-zero and equals (4 π times) the matter density in all reference frames. While the Ricci field equation and Gauss' law are fulfilled by the physical matter density in inertial and linearly accelerating reference frames, in rotating reference frames Gauss' law holds for an effective mass density that differs from the physical matter density. This effective density has its origin in the simulated magnetic field of rotating frames, highlighting a striking difference between linearly and rotationally accelerating frames. The equations governing the simulated fields have the same form as Maxwell's equations, a surprising result given that these equations obey special relativity (and U (1) -gauge symmetry), rather than Galilean symmetry. This work was supported in part by the HHMI Undergraduate Science Education Award 52006298 and the Grinnell College Academic Affairs' CSFS and MAP programs.

  19. Accelerating universe and the time-dependent fine-structure constant

    NASA Astrophysics Data System (ADS)

    Fujii, Yasunori

    2010-11-01

    I start with assuming a gravitational scalar field as the dark-energy supposed to be responsible for the accelerating universe. Also from the point of view of unification, a scalar field implies a time-variability of certain “constants” in Nature. In this context I once derived a relation for the time-variability of the fine-structure constant α: Δα/α =ζ Ƶ(α/π) Δσ, where ζ and Ƶ are the constants of the order one, while σ on the right-hand side is the scalar field in action in the accelerating universe. I use the reduced Planckian units with c=ℏ =MP(=(8π G)-1/2)=1. I then compared the dynamics of the accelerating universe, on one hand, and Δα/α derived from the analyses of QSO absorption lines, Oklo phenomenon, also different atomic clocks in the laboratories, on the other hand. I am here going to discuss the theoretical background of the relation, based on the scalar-tensor theory invented first by Jordan in 1955.

  20. Freezing, accelerating, and slowing directed currents in real time with superimposed driven lattices

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Aritra K.; Liebchen, Benno; Wulf, Thomas; Schmelcher, Peter

    2016-05-01

    We provide a generic scheme offering real-time control of directed particle transport using superimposed driven lattices. This scheme allows one to accelerate, slow, and freeze the transport on demand by switching one of the lattices subsequently on and off. The underlying physical mechanism hinges on a systematic opening and closing of channels between transporting and nontransporting phase space structures upon switching and exploits cantori structures which generate memory effects in the population of these structures. Our results should allow for real-time control of cold thermal atomic ensembles in optical lattices but might also be useful as a design principle for targeted delivery of molecules or colloids in optical devices.

  1. Three-dimensional, Time-Resolved, Intrafraction Motion Monitoring Throughout Stereotactic Liver Radiation Therapy on a Conventional Linear Accelerator

    SciTech Connect

    Worm, Esben S.; Høyer, Morten; Fledelius, Walter; Poulsen, Per R.

    2013-05-01

    Purpose: To investigate the time-resolved 3-dimensional (3D) internal motion throughout stereotactic body radiation therapy (SBRT) of tumors in the liver using standard x-ray imagers of a conventional linear accelerator. Methods and Materials: Ten patients with implanted gold markers received 11 treatment courses of 3-fraction SBRT in a stereotactic body-frame on a conventional linear accelerator. Two pretreatment and 1 posttreatment cone-beam computed tomography (CBCT) scans were acquired during each fraction. The CBCT projection images were used to estimate the internal 3D marker motion during CBCT acquisition with 11-Hz resolution by a monoscopic probability-based method. Throughout the treatment delivery by conformal or volumetric modulated arc fields, simultaneous MV portal imaging (8 Hz) and orthogonal kV imaging (5 Hz) were applied to determine the 3D marker motion using either MV/kV triangulation or the monoscopic method when marker segmentation was unachievable in either MV or kV images. The accuracy of monoscopic motion estimation was quantified by also applying monoscopic estimation as a test for all treatments during which MV/kV triangulation was possible. Results: Root-mean-square deviations between monoscopic estimations and triangulations were less than 1.0 mm. The mean 3D intrafraction and intrafield motion ranges during liver SBRT were 17.6 mm (range, 5.6-39.5 mm) and 11.3 mm (2.1-35.5mm), respectively. The risk of large intrafraction baseline shifts correlated with intrafield respiratory motion range. The mean 3D intrafractional marker displacement relative to the first CBCT was 3.4 mm (range, 0.7-14.5 mm). The 3D displacements exceeded 8.8 mm 10% of the time. Conclusions: Highly detailed time-resolved internal 3D motion was determined throughout liver SBRT using standard imaging equipment. Considerable intrafraction motion was observed. The demonstrated methods provide a widely available approach for motion monitoring that, combined with motion

  2. Application of real-time digitization techniques in beam measurement for accelerators

    NASA Astrophysics Data System (ADS)

    Zhao, Lei; Zhan, Lin-Song; Gao, Xing-Shun; Liu, Shu-Bin; An, Qi

    2016-04-01

    Beam measurement is very important for accelerators. In this paper, modern digital beam measurement techniques based on IQ (In-phase & Quadrature-phase) analysis are discussed. Based on this method and high-speed high-resolution analog-to-digital conversion, we have completed three beam measurement electronics systems designed for the China Spallation Neutron Source (CSNS), Shanghai Synchrotron Radiation Facility (SSRF), and Accelerator Driven Sub-critical system (ADS). Core techniques of hardware design and real-time system calibration are discussed, and performance test results of these three instruments are also presented. Supported by National Natural Science Foundation of China (11205153, 10875119), Knowledge Innovation Program of the Chinese Academy of Sciences (KJCX2-YW-N27), and the Fundamental Research Funds for the Central Universities (WK2030040029),and the CAS Center for Excellence in Particle Physics (CCEPP).

  3. Evaluation of Linear Accelerator Gating With Real-Time Electromagnetic Tracking

    SciTech Connect

    Smith, Ryan L.; Lechleiter, Kristen; Malinowski, Kathleen; Shepard, D.M.; Housley, D.J.; Afghan, M.; Newell, Jeff; Petersen, Jay; Sargent, Brian; Parikh, Parag

    2009-07-01

    Purpose: Intrafraction organ motion can produce dosimetric errors in radiotherapy. Commonly, the linear accelerator is gated using real-time breathing phase obtained by way of external sensors. However, the external anatomy does not always correlate well with the internal position. We examined a beam gating technique using signals from implanted wireless transponders that provided real-time feedback on the tumor location without an imaging dose to the patient. Methods and Materials: An interface was developed between Calypso Medical's four-dimensional electromagnetic tracking system and a Varian Trilogy linear accelerator. A film phantom was mounted on a motion platform programmed with lung motion trajectories. Deliveries were performed when the beam was gated according to the signal from the wireless transponders. The dosimetric advantages of beam gating and the system latencies were quantified. Results: Beam gating using on internal position monitoring provided up to a twofold increase in the dose gradients. The percentage of points failing to be within {+-}10 cGy of the planned dose (maximal dose, {approx}200 cGy) was 3.4% for gating and 32.1% for no intervention in the presence of motion. The mean latencies between the transponder position and linear accelerator modulation were 75.0 {+-}12.7 ms for beam on and 65.1 {+-} 12.9 ms for beam off. Conclusion: We have presented the results from a novel method for gating the linear accelerator using trackable wireless internal fiducial markers without the use of ionizing radiation for imaging. The latencies observed were suitable for gating using electromagnetic fiducial markers, which results in dosimetric improvements for irradiation in the presence of motion.

  4. Analysis of accelerated failure time data with dependent censoring using auxiliary variables via nonparametric multiple imputation.

    PubMed

    Hsu, Chiu-Hsieh; Taylor, Jeremy M G; Hu, Chengcheng

    2015-08-30

    We consider the situation of estimating the marginal survival distribution from censored data subject to dependent censoring using auxiliary variables. We had previously developed a nonparametric multiple imputation approach. The method used two working proportional hazards (PH) models, one for the event times and the other for the censoring times, to define a nearest neighbor imputing risk set. This risk set was then used to impute failure times for censored observations. Here, we adapt the method to the situation where the event and censoring times follow accelerated failure time models and propose to use the Buckley-James estimator as the two working models. Besides studying the performances of the proposed method, we also compare the proposed method with two popular methods for handling dependent censoring through the use of auxiliary variables, inverse probability of censoring weighted and parametric multiple imputation methods, to shed light on the use of them. In a simulation study with time-independent auxiliary variables, we show that all approaches can reduce bias due to dependent censoring. The proposed method is robust to misspecification of either one of the two working models and their link function. This indicates that a working proportional hazards model is preferred because it is more cumbersome to fit an accelerated failure time model. In contrast, the inverse probability of censoring weighted method is not robust to misspecification of the link function of the censoring time model. The parametric imputation methods rely on the specification of the event time model. The approaches are applied to a prostate cancer dataset.

  5. Nonsingular exponential gravity: A simple theory for early- and late-time accelerated expansion

    SciTech Connect

    Elizalde, E.; Odintsov, S. D.; Sebastiani, L.; Zerbini, S.

    2011-04-15

    A theory of exponential modified gravity which explains both early-time inflation and late-time acceleration, in a unified way, is proposed. The theory successfully passes the local tests and fulfills the cosmological bounds and, remarkably, the corresponding inflationary era is proven to be unstable. Numerical investigation of its late-time evolution leads to the conclusion that the corresponding dark energy epoch is not distinguishable from the one for the {Lambda}CDM model. Several versions of this exponential gravity, sharing similar properties, are formulated. It is also shown that this theory is nonsingular, being protected against the formation of finite-time future singularities. As a result, the corresponding future universe evolution asymptotically tends, in a smooth way, to de Sitter space, which turns out to be the final attractor of the system.

  6. Time-resolved energy spectrum measurement of a linear induction accelerator with the magnetic analyzer

    NASA Astrophysics Data System (ADS)

    Wang, Yuan; Jiang, Xiao-Guo; Yang, Guo-Jun; Chen, Si-Fu; Zhang, Zhuo; Wei, Tao; Li, Jin

    2015-01-01

    We recently set up a time-resolved optical beam diagnostic system. Using this system, we measured the high current electron beam energy in the accelerator under construction. This paper introduces the principle of the diagnostic system, describes the setup, and shows the results. A bending beam line was designed using an existing magnetic analyzer with a 300 mm-bending radius and a 60° bending angle at hard-edge approximation. Calculations show that the magnitude of the beam energy is about 18 MeV, and the energy spread is within 2%. Our results agree well with the initial estimates deduced from the diode voltage approach.

  7. Protecting and accelerating adiabatic passage with time-delayed pulse sequences.

    PubMed

    Sampedro, Pablo; Chang, Bo Y; Sola, Ignacio R

    2016-05-21

    Using numerical simulations of two-photon electronic absorption with femtosecond pulses in Na2 we show that: (i) it is possible to avoid the characteristic saturation or dumped Rabi oscillations in the yield of absorption by time-delaying the laser pulses; (ii) it is possible to accelerate the onset of adiabatic passage by using the vibrational coherence starting in a wave packet; and (iii) it is possible to prepare the initial wave packet in order to achieve full state-selective transitions with broadband pulses. The findings can be used, for instance, to achieve ultrafast adiabatic passage by light-induced potentials and understand its intrinsic robustness. PMID:27125342

  8. Protecting and accelerating adiabatic passage with time-delayed pulse sequences.

    PubMed

    Sampedro, Pablo; Chang, Bo Y; Sola, Ignacio R

    2016-05-21

    Using numerical simulations of two-photon electronic absorption with femtosecond pulses in Na2 we show that: (i) it is possible to avoid the characteristic saturation or dumped Rabi oscillations in the yield of absorption by time-delaying the laser pulses; (ii) it is possible to accelerate the onset of adiabatic passage by using the vibrational coherence starting in a wave packet; and (iii) it is possible to prepare the initial wave packet in order to achieve full state-selective transitions with broadband pulses. The findings can be used, for instance, to achieve ultrafast adiabatic passage by light-induced potentials and understand its intrinsic robustness.

  9. Simulating the effects of timing and energy stability in a laser wakefield accelerator with external injection

    SciTech Connect

    Dijk, W. van; Corstens, J. M.; Stragier, X. F. D.; Brussaard, G. J. H.; Geer, S. B. van der

    2009-01-22

    One of the most compelling reasons to use external injection of electrons into a laser wakefield accelerator is to improve the stability and reproducibility of the accelerated electrons. We have built a simulation tool based on particle tracking to investigate the expected output parameters. Specifically, we are simulating the variations in energy and bunch charge under the influence of variations in laser power and timing jitter. In these simulations a a{sub 0} = 0.32 to a{sub 0} = 1.02 laser pulse with 10% shot-to-shot energy fluctuation is focused into a plasma waveguide with a density of 1.0x10{sup 24} m{sup -3} and a calculated matched spot size of 50.2 {mu}m. The timing of the injected electron bunch with respect to the laser pulse is varied from up to 1 ps from the standard timing (1 ps ahead or behind the laser pulse, depending on the regime). The simulation method and first results will be presented. Shortcomings and possible extensions to the model will be discussed.

  10. Accelerating Time Integration for the Shallow Water Equations on the Sphere Using GPUs

    DOE PAGES

    Archibald, R.; Evans, K. J.; Salinger, A.

    2015-06-01

    The push towards larger and larger computational platforms has made it possible for climate simulations to resolve climate dynamics across multiple spatial and temporal scales. This direction in climate simulation has created a strong need to develop scalable time-stepping methods capable of accelerating throughput on high performance computing. This work details the recent advances in the implementation of implicit time stepping on a spectral element cube-sphere grid using graphical processing units (GPU) based machines. We demonstrate how solvers in the Trilinos project are interfaced with ACME and GPU kernels can significantly increase computational speed of the residual calculations in themore » implicit time stepping method for the shallow water equations on the sphere. We show the optimization gains and data structure reorganization that facilitates the performance improvements.« less

  11. Accelerating Time Integration for the Shallow Water Equations on the Sphere Using GPUs

    SciTech Connect

    Archibald, R.; Evans, K. J.; Salinger, A.

    2015-06-01

    The push towards larger and larger computational platforms has made it possible for climate simulations to resolve climate dynamics across multiple spatial and temporal scales. This direction in climate simulation has created a strong need to develop scalable time-stepping methods capable of accelerating throughput on high performance computing. This work details the recent advances in the implementation of implicit time stepping on a spectral element cube-sphere grid using graphical processing units (GPU) based machines. We demonstrate how solvers in the Trilinos project are interfaced with ACME and GPU kernels can significantly increase computational speed of the residual calculations in the implicit time stepping method for the shallow water equations on the sphere. We show the optimization gains and data structure reorganization that facilitates the performance improvements.

  12. A charged particle in a homogeneous magnetic field accelerated by a time-periodic Aharonov-Bohm flux

    SciTech Connect

    Kalvoda, T.; Stovicek, P.

    2011-10-15

    We consider a nonrelativistic quantum charged particle moving on a plane under the influence of a uniform magnetic field and driven by a periodically time-dependent Aharonov-Bohm flux. We observe an acceleration effect in the case when the Aharonov-Bohm flux depends on time as a sinusoidal function whose frequency is in resonance with the cyclotron frequency. In particular, the energy of the particle increases linearly for large times. An explicit formula for the acceleration rate is derived with the aid of the quantum averaging method, and then it is checked against a numerical solution and a very good agreement is found. - Highlights: > A nonrelativistic quantum charged particle on a plane. > A homogeneous magnetic field and a periodically time-dependent Aharonov-Bohm flux. > The quantum averaging method applied to a time-dependent system. > A resonance of the AB flux with the cyclotron frequency. > An acceleration with linearly increasing energy; a formula for the acceleration rate.

  13. Time dependent diffusive shock acceleration and its application to middle aged supernova remnants

    NASA Astrophysics Data System (ADS)

    Tang, Xiaping; Chevalier, Roger A.

    2016-06-01

    Recent gamma-ray observations show that middle aged supernova remnants (SNRs) interacting with molecular clouds (MCs) can be sources of both GeV and TeV emission. Based on the MC association, two scenarios have been proposed to explain the observed gamma-ray emission. In one, energetic cosmic ray (CR) particles escape from the SNR and then illuminate nearby MCs, producing gamma-ray emission, while the other involves direct interaction between the SNR and MC. In the direct interaction scenario, re-acceleration of pre-existing CRs in the ambient medium is investigated while particles injected from the thermal pool are neglected in view of the slow shock speeds in middle aged SNRs. However, standard diffusive shock acceleration (DSA) theory produces a steady state particle spectrum that is too flat compared to observations, which suggests that the high energy part of the observed spectrum has not yet reached a steady state. We derive a time dependent DSA solution in the test particle limit for re-acceleration of pre-existing CRs case and show that it is capable of reproducing the observed gamma-ray emission in SNRs like IC 443 and W44, in the context of a MC interaction model. We also provide a simple physical picture to understand the time dependent DSA spectrum. A spatially averaged diffusion coefficient around the SNR can be estimated through fitting the gamma-ray spectrum. The spatially averaged diffusion coefficient in middle aged SNRs like IC 443 and W44 is estimated to be ~10^(25) cm^2/s at ~ 1GeV, which is between the Bohm limit and interstellar value.

  14. Gauss-Bonnet cosmology unifying late and early-time acceleration eras with intermediate eras

    NASA Astrophysics Data System (ADS)

    Oikonomou, V. K.

    2016-07-01

    In this paper we demonstrate that with vacuum F(G) gravity it is possible to describe the unification of late and early-time acceleration eras with the radiation and matter domination era. The Hubble rate of the unified evolution contains two mild singularities, so called Type IV singularities, and the evolution itself has some appealing features, such as the existence of a deceleration-acceleration transition at late times. We also address quantitatively a fundamental question related to modified gravity models description of cosmological evolution: Is it possible for all modified gravity descriptions of our Universe evolution, to produce a nearly scale invariant spectrum of primordial curvature perturbations? As we demonstrate, the answer for the F(G) description is no, since the resulting power spectrum is not scale invariant, in contrast to the F(R) description studied in the literature. Therefore, although the cosmological evolution can be realized in the context of vacuum F(G) gravity, the evolution is not compatible with the observational data, in contrast to the F(R) gravity description of the same cosmological evolution.

  15. High frame-rate real-time x-ray imaging of in situ high-velocity rifle bullets

    NASA Astrophysics Data System (ADS)

    D'Aries, Lawrence J.; Miller, Stuart R.; Robertson, Rob; Singh, Bipin; Nagarkar, Vivek V.

    2016-05-01

    High frame-rate imaging is a valuable tool for non-destructive evaluation (NDE) as well as for ballistic impact studies (terminal ballistics), in-flight projectile imaging, studies of exploding ordnance and characterization of other high-speed phenomena. Current imaging systems exist for these studies, however, none have the ability to do in-barrel characterization (in-bore ballistics) to image kinetics of the moving projectile BEFORE it exits the barrel. The system uses an intensified high-speed CMOS camera coupled to a specially designed scintillator to serve as the X-ray detector. The X-ray source is a sequentially fired portable pulsed unit synchronized with the detector integration window and is able to acquire 3,600 frames per second (fps) with mega-pixel spatial resolution and up to 500,000 fps with reduced pixel resolution. This paper will discuss our results imaging .30 caliber bullets traveling at ~1,000 m/s while still in the barrel. Information on bullet deformation, pitch, yaw and integrity are the main goals of this experimentation. Planned future upgrades for imaging large caliber projectiles will also be discussed.

  16. The effects of gait time and trunk acceleration ratio during stair climbing in old-old adult females.

    PubMed

    Shin, Sun-Shil; Yoo, Won-Gyu

    2016-07-01

    [Purpose] This study investigated the effects of gait time and trunk acceleration ratio in old-old adult females during stair climbing. [Subjects and Methods] Twenty-five older adult females who were able to walk independently volunteered for this study and were categorized into two age groups (older adults or old-old adults). Gait time and trunk acceleration ratio were measured using an accelerometer during stair climbing. [Results] Gait time and trunk acceleration ratio when climbing stairs were significantly higher in the old-old age group than in the older adults group. [Conclusions] These findings suggest that old-old females have decreased upper trunk control. In addition, gait time and the trunk acceleration ratio during stair climbing are useful clinical markers for predicting function and balance control ability in old-old elderly populations. PMID:27512256

  17. The effects of gait time and trunk acceleration ratio during stair climbing in old-old adult females

    PubMed Central

    Shin, Sun-Shil; Yoo, Won-Gyu

    2016-01-01

    [Purpose] This study investigated the effects of gait time and trunk acceleration ratio in old-old adult females during stair climbing. [Subjects and Methods] Twenty-five older adult females who were able to walk independently volunteered for this study and were categorized into two age groups (older adults or old-old adults). Gait time and trunk acceleration ratio were measured using an accelerometer during stair climbing. [Results] Gait time and trunk acceleration ratio when climbing stairs were significantly higher in the old-old age group than in the older adults group. [Conclusions] These findings suggest that old-old females have decreased upper trunk control. In addition, gait time and the trunk acceleration ratio during stair climbing are useful clinical markers for predicting function and balance control ability in old-old elderly populations. PMID:27512256

  18. Three Accelerated Developmental Education Programs: Features, Student Outcomes, and Implications

    ERIC Educational Resources Information Center

    Jaggars, Shanna Smith; Hodara, Michelle; Cho, Sung-Woo; Xu, Di

    2015-01-01

    To support the long-term success of underprepared students, many community colleges are experimenting with accelerated developmental education models, which allow students to complete remediation and enroll in college-level math and English within a shorter time frame. This study examines three developmental acceleration programs, including two in…

  19. Acceleration of yoghurt fermentation time by yeast extract and partial characterisation of the active components.

    PubMed

    Smith, Esti-Andrine; Myburgh, Jacobus; Osthoff, Gernot; de Wit, Maryna

    2014-11-01

    Water soluble autolysate of yeast, usually utilised for microbial growth support, was used as additive in yoghurt fermentation. The yeast extract (YE) resulted in a decrease of fermentation time by 21% to reach a pH of 4·6. However, the YE resulted in unacceptable flavour and taste. By size exclusion chromatography, a fraction of the YE was obtained that could account for the observed 21% decrease in fermentation time. The fraction contained molecules of low molecular weight, consisting of minerals, free amino acids and peptides. The acceleration of the yoghurt fermentation was ascribed to the short peptides in the fraction. It is proposed that the application of this extract in industrial yoghurt manufacture would result in savings for both the industry and the consumer.

  20. Accumulation of accelerated electrons in coronal loops and time delays of solar flare nonthermal emission

    NASA Astrophysics Data System (ADS)

    Tsap, Yu. T.; Stepanov, A. V.; Kopylova, Yu. G.

    2015-12-01

    The mechanisms by which accelerated electrons accumulate in flare loops with regard to the observed time delays between peaks of prolonged (≫1 s) hard X-ray pulses with different energies are considered. The focus is on an analysis of electron pitch-angle scattering by background plasma particles and/or turbulent pulsations in extreme cases of frequent and rare collisions. It was shown that it is difficult to explain the origination of time delays in the scope of a diffusion model when the electron free path length ( l) in the corona is smaller than the flare loop length ( L). The accumulation of energetic particles in loops at l > L is related to a trap-plus-precipitation model in which the regime of weak pitch angle diffusion of trapped electrons in the loss cone predominates.

  1. Identifying Issue Frames in Text

    PubMed Central

    Sagi, Eyal; Diermeier, Daniel; Kaufmann, Stefan

    2013-01-01

    Framing, the effect of context on cognitive processes, is a prominent topic of research in psychology and public opinion research. Research on framing has traditionally relied on controlled experiments and manually annotated document collections. In this paper we present a method that allows for quantifying the relative strengths of competing linguistic frames based on corpus analysis. This method requires little human intervention and can therefore be efficiently applied to large bodies of text. We demonstrate its effectiveness by tracking changes in the framing of terror over time and comparing the framing of abortion by Democrats and Republicans in the U.S. PMID:23874909

  2. Time-scale bias in evidence for anthropogenic acceleration of soil erosion and floodplain accretion

    NASA Astrophysics Data System (ADS)

    Willenbring, J. K.; Hoffmann, T.; Sadler, P.; Kaplan, J. O.; Chiverrell, R. C.; Erkens, G.; von Blanckenburg, F.

    2014-12-01

    The claim that humans modify the landscape more dramatically than any previous geological agent has impacts for river restoration, conservation and models of both nutrient- and carbon-cycling. This view of extreme sediment mobilization driven by human activities is largely based on data, which unfortunately are measured over discrepant timescales that can introduce bias. Comparing denudation rates discerned from cosmogenic nuclides as 'baseline' or 'natural' rates with continent-scale sediment export rates over modern timescales reveals that most cosmogenic nuclide-based erosion rates are faster than human-impacted rates of sediment yield [1]. One explanation for relatively low recent continental sediment yields is that the eroded sediment may be accumulating and stored for an uncertain duration in swelling floodplains and deltas. We present a global compilation of Holocene floodplain accumulation rates. Rates measured over the last ~100 years are faster than those averaged over ~1000 years, which in turn are faster than those for the last ~10000 years. Floodplain sediment accumulation measurements, however, are taken at discreet cores or bank exposures, and this introduces both temporal and spatial bias. Vertical accumulation rates are calculated by dividing thickness of sediment by the time-span of accumulation for discrete packages of sediment. Thus, time integrates from the present to a past datum provided by 14C measurements for buried organics (or other chronological tools). We argue that the pattern of rate increase in sedimentation over time is related to infilling behavior of all floodplains and not specifically tied to the supply of (anthropogenic) sediment. The apparent acceleration in sedimentation rates appears globally synchronous over 8000-year timescales, despite diachronous human and land use histories. Moreover, some rate acceleration pre-dates significant human land use. When the effect/bias of averaging time is accounted for, recent accumulation

  3. On the Impact of a Quadratic Acceleration Term in the Analysis of Position Time Series

    NASA Astrophysics Data System (ADS)

    Bogusz, Janusz; Klos, Anna; Bos, Machiel Simon; Hunegnaw, Addisu; Teferle, Felix Norman

    2016-04-01

    The analysis of Global Navigation Satellite System (GNSS) position time series generally assumes that each of the coordinate component series is described by the sum of a linear rate (velocity) and various periodic terms. The residuals, the deviations between the fitted model and the observations, are then a measure of the epoch-to-epoch scatter and have been used for the analysis of the stochastic character (noise) of the time series. Often the parameters of interest in GNSS position time series are the velocities and their associated uncertainties, which have to be determined with the highest reliability. It is clear that not all GNSS position time series follow this simple linear behaviour. Therefore, we have added an acceleration term in the form of a quadratic polynomial function to the model in order to better describe the non-linear motion in the position time series. This non-linear motion could be a response to purely geophysical processes, for example, elastic rebound of the Earth's crust due to ice mass loss in Greenland, artefacts due to deficiencies in bias mitigation models, for example, of the GNSS satellite and receiver antenna phase centres, or any combination thereof. In this study we have simulated 20 time series with different stochastic characteristics such as white, flicker or random walk noise of length of 23 years. The noise amplitude was assumed at 1 mm/y-/4. Then, we added the deterministic part consisting of a linear trend of 20 mm/y (that represents the averaged horizontal velocity) and accelerations ranging from minus 0.6 to plus 0.6 mm/y2. For all these data we estimated the noise parameters with Maximum Likelihood Estimation (MLE) using the Hector software package without taken into account the non-linear term. In this way we set the benchmark to then investigate how the noise properties and velocity uncertainty may be affected by any un-modelled, non-linear term. The velocities and their uncertainties versus the accelerations for

  4. Real-time diagnostic for charging and damage of dielectrics in accelerators

    NASA Astrophysics Data System (ADS)

    Shchelkunov, S. V.; Marshall, T. C.; Hirshfield, J. L.

    2016-09-01

    We report on the progress made during the initial stage of our research to study charging rate and charge distribution in a thin walled dielectric wakefield accelerator (DWA) from a passing charge bunch and the physics of conductivity and discharge phenomena in dielectric materials useful in accelerator applications. The issue is the role played by the beam halo and intense wakefields in charging the dielectric, possibly leading to undesired deflection of charge bunches and degradation of the dielectric material: the effects that may grow over many pulses, albeit perhaps differently at different repetition rates. During the initial stage of development, a microwave apparatus was built and signal processing was developed to observe time-dependent charging of dielectric surfaces and/or plasmas located on or near the inner surface of a thin-wall hollow dielectric tube. Three frequencies were employed to improve the data handling rate and the signal-to-noise. The test and performance results for a plasma test case are presented; in particular, the performance of the test unit shows capability to detect small changes ~0.1% of a dielectric constant, which would correspond to the scraping-off of only 0.3 nC to the walls of the dielectric liner inside the cavity from the passing charge bunch.

  5. Time-dependent Models for Blazar Emission with the Second-order Fermi Acceleration

    NASA Astrophysics Data System (ADS)

    Asano, Katsuaki; Takahara, Fumio; Kusunose, Masaaki; Toma, Kenji; Kakuwa, Jun

    2014-01-01

    The second-order Fermi acceleration (Fermi-II) driven by turbulence may be responsible for the electron acceleration in blazar jets. We test this model with time-dependent simulations. The hard electron spectrum predicted by the Fermi-II process agrees with the hard photon spectrum of 1ES 1101-232. For other blazars that show softer spectra, the Fermi-II model requires radial evolution of the electron injection rate and/or diffusion coefficient in the outflow. Such evolutions can yield a curved electron spectrum, which can reproduce the synchrotron spectrum of Mrk 421 from the radio to the X-ray regime. The photon spectrum in the GeV energy range of Mrk 421 is hard to fit with a synchrotron self-Compton model. However, if we introduce an external radio photon field with a luminosity of 4.9 × 1038 erg s-1, GeV photons are successfully produced via inverse Compton scattering. The temporal variability of the diffusion coefficient or injection rate causes flare emission. The observed synchronicity of X-ray and TeV flares implies a decrease of the magnetic field in the flaring source region.

  6. Time-dependent models for blazar emission with the second-order Fermi acceleration

    SciTech Connect

    Asano, Katsuaki; Takahara, Fumio; Toma, Kenji; Kusunose, Masaaki; Kakuwa, Jun

    2014-01-01

    The second-order Fermi acceleration (Fermi-II) driven by turbulence may be responsible for the electron acceleration in blazar jets. We test this model with time-dependent simulations. The hard electron spectrum predicted by the Fermi-II process agrees with the hard photon spectrum of 1ES 1101–232. For other blazars that show softer spectra, the Fermi-II model requires radial evolution of the electron injection rate and/or diffusion coefficient in the outflow. Such evolutions can yield a curved electron spectrum, which can reproduce the synchrotron spectrum of Mrk 421 from the radio to the X-ray regime. The photon spectrum in the GeV energy range of Mrk 421 is hard to fit with a synchrotron self-Compton model. However, if we introduce an external radio photon field with a luminosity of 4.9 × 10{sup 38} erg s{sup –1}, GeV photons are successfully produced via inverse Compton scattering. The temporal variability of the diffusion coefficient or injection rate causes flare emission. The observed synchronicity of X-ray and TeV flares implies a decrease of the magnetic field in the flaring source region.

  7. Analytic approach to nonlinear hydrodynamic instabilities driven by time-dependent accelerations

    SciTech Connect

    Mikaelian, K O

    2009-09-28

    We extend our earlier model for Rayleigh-Taylor and Richtmyer-Meshkov instabilities to the more general class of hydrodynamic instabilities driven by a time-dependent acceleration g(t) . Explicit analytic solutions for linear as well as nonlinear amplitudes are obtained for several g(t)'s by solving a Schroedinger-like equation d{sup 2}{eta}/dt{sup 2} - g(t)kA{eta} = 0 where A is the Atwood number and k is the wavenumber of the perturbation amplitude {eta}(t). In our model a simple transformation k {yields} k{sub L} and A {yields} A{sub L} connects the linear to the nonlinear amplitudes: {eta}{sup nonlinear} (k,A) {approx} (1/k{sub L})ln{eta}{sup linear} (k{sub L}, A{sub L}). The model is found to be in very good agreement with direct numerical simulations. Bubble amplitudes for a variety of accelerations are seen to scale with s defined by s = {integral} {radical}g(t)dt, while spike amplitudes prefer scaling with displacement {Delta}x = {integral}[{integral}g(t)dt]dt.

  8. Merging metadynamics into hyperdynamics: accelerated molecular simulations reaching time scales from microseconds to seconds.

    PubMed

    Bal, Kristof M; Neyts, Erik C

    2015-10-13

    The hyperdynamics method is a powerful tool to simulate slow processes at the atomic level. However, the construction of an optimal hyperdynamics potential is a task that is far from trivial. Here, we propose a generally applicable implementation of the hyperdynamics algorithm, borrowing two concepts from metadynamics. First, the use of a collective variable (CV) to represent the accelerated dynamics gives the method a very large flexibility and simplicity. Second, a metadynamics procedure can be used to construct a suitable history-dependent bias potential on-the-fly, effectively turning the algorithm into a self-learning accelerated molecular dynamics method. This collective variable-driven hyperdynamics (CVHD) method has a modular design: both the local system properties on which the bias is based, as well as the characteristics of the biasing method itself, can be chosen to match the needs of the considered system. As a result, system-specific details are abstracted from the biasing algorithm itself, making it extremely versatile and transparent. The method is tested on three model systems: diffusion on the Cu(001) surface and nickel-catalyzed methane decomposition, as examples of “reactive” processes with a bond-length-based CV, and the folding of a long polymer-like chain, using a set of dihedral angles as a CV. Boost factors up to 109, corresponding to a time scale of seconds, could be obtained while still accurately reproducing correct dynamics.

  9. Interaction of HTLV-1 Tax with minichromosome maintenance proteins accelerates the replication timing program.

    PubMed

    Boxus, Mathieu; Twizere, Jean-Claude; Legros, Sébastien; Kettmann, Richard; Willems, Luc

    2012-01-01

    The Tax oncoprotein encoded by the human T-cell leukemia virus type 1 plays a pivotal role in viral persistence and pathogenesis. Human T-cell leukemia virus type 1-infected cells proliferate faster than normal lymphocytes, expand through mitotic division, and accumulate genomic lesions. Here, we show that Tax associates with the minichromosome maintenance MCM2-7 helicase complex and localizes to origins of replication. Tax modulates the spatiotemporal program of origin activation and fires supplementary origins at the onset of S phase. Thereby, Tax increases the DNA replication rate, accelerates S phase progression, but also generates a replicative stress characterized by the presence of genomic lesions. Mechanistically, Tax favors p300 recruitment and histone hyperacetylation at late replication domains, advancing their replication timing in early S phase. PMID:22058115

  10. Early inflation to late-time acceleration in f(G) model

    NASA Astrophysics Data System (ADS)

    Dutta, Malay Krishna; Sarkar, Kaushik; Modak, B.

    2016-09-01

    We present some solutions in Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime in the modified theory of gravity with a general Gauss-Bonnet (GB) term f(G) and R2 including an ideal fluid. We present evolution of the universe introducing an ansatz without a prior choice of f(G) in one approach, while in other class of model, the solutions are obtained assuming few simple forms of f(G). Some of the solutions show early inflationary expansion, further in one solution the fluctuation of the deceleration parameter q is evident at the end of inflation. In all cases, late-time transition to accelerating universe at redshift z ˜ 0.7 is realizable.

  11. A smoothing expectation and substitution algorithm for the semiparametric accelerated failure time frailty model.

    PubMed

    Johnson, Lynn M; Strawderman, Robert L

    2012-09-20

    This paper proposes an estimation procedure for the semiparametric accelerated failure time frailty model that combines smoothing with an Expectation and Maximization-like algorithm for estimating equations. The resulting algorithm permits simultaneous estimation of the regression parameter, the baseline cumulative hazard, and the parameter indexing a general frailty distribution. We develop novel moment-based estimators for the frailty parameter, including a generalized method of moments estimator. Standard error estimates for all parameters are easily obtained using a randomly weighted bootstrap procedure. For the commonly used gamma frailty distribution, the proposed algorithm is very easy to implement using widely available numerical methods. Simulation results demonstrate that the algorithm performs very well in this setting. We re-analyz several previously analyzed data sets for illustrative purposes.

  12. On using moving windows in finite element time domain simulation for long accelerator structures

    SciTech Connect

    Lee, L.-Q.; Candel, Arno; Ng, Cho; Ko, Kwok

    2010-12-10

    A finite element moving window technique is developed to simulate the propagation of electromagnetic waves induced by the transit of a charged particle beam inside large and long structures. The window moving along with the beam in the computational domain adopts high-order finite element basis functions through p refinement and/or a high-resolution mesh through h refinement so that a sufficient accuracy is attained with substantially reduced computational costs. Algorithms to transfer discretized fields from one mesh to another, which are the keys to implementing a moving window in a finite element unstructured mesh, are presented. Numerical experiments are carried out using the moving window technique to compute short-range wakefields in long accelerator structures. The results are compared with those obtained from the normal finite element time domain (FETD) method and the advantages of using the moving window technique are discussed.

  13. Control, timing, and data acquisition for the Argonne Wakefield Accelerator (AWA)

    SciTech Connect

    Schoessow, P.; Ho, C.; Power, J.; Chojnacki, E.

    1993-08-01

    The AWA is a new facility primarily designed for wakefield acceleration experiments at the 100 MV/m scale, which incorporates a high current linac and rf photocathode electron source, a low emittance rf electron gun for witness beam generation, and associated beamlines and diagnostics. The control system is based on VME and CA-MAC electronics interfaced to a high performance work-station and provides some distributed processing capability. In addition to the control of linac rf, laser optics, and beamlines, the system is also used for acquisition of video data both from luminescent beam position monitors and from streak camera pulse length diagnostics. Online image feature extraction will permit wakefields to be computed during the course of data taking. The linac timing electronics and its interface to the control system is described.

  14. Three classes of space-time with a uniformly accelerating and nonrotating gravitational source

    NASA Astrophysics Data System (ADS)

    Ishikawa, K.-I.; Miyashita, T.

    1983-11-01

    In his study of Einstein spaces, Petrov (1969) has classified curvature tensors algebraically. The present investigation is concerned with the type-D empty spaces which possess a degenerate principal null vector tangent to expanding and nonrotating null geodesic congruences. These spaces have been represented by the C metric. Ishikawa and Miyashita (1982) have conducted a classification of the type-D empty spaces. In the current study, the physical properties of space-time of the three classes are explored. In a representation of the metric forms of the three classes, use is made of the Eddington-Finkelstein type of null coordinates. It is shown that the considered classes can be interpreted as a gravitational field of a uniformly accelerating source which moves with a velocity which is equal to that of light, or either slower or faster than it.

  15. Real-time dose computation: GPU-accelerated source modeling and superposition/convolution

    SciTech Connect

    Jacques, Robert; Wong, John; Taylor, Russell; McNutt, Todd

    2011-01-15

    } times were 8.3 and 94 s, respectively, on an AMD (Sunnyvale, CA) Opteron 254 (two cores, 2.8 GHz). Conclusions: The authors have completed a comprehensive, GPU-accelerated dose engine in order to provide a substantial performance gain over CPU based implementations. Real-time dose computation is feasible with the accuracy levels of the superposition/convolution algorithm.

  16. Dynamic inversion method based on the time-staggered stereo-modeling scheme and its acceleration

    NASA Astrophysics Data System (ADS)

    Jing, Hao; Yang, Dinghui; Wu, Hao

    2016-09-01

    A set of second-order differential equations describing the space-time behavior of derivatives of displacement with respect to model parameters (i.e. waveform sensitivities) is obtained via taking the derivative of the original wave equations. The dynamic inversion method obtains sensitivities of the seismic displacement field with respect to earth properties directly by solving differential equations for them instead of constructing sensitivities from the displacement field itself. In this study, we have taken a new perspective on the dynamic inversion method and used acceleration approaches to reduce the computational time and memory usage to improve its ability of performing high-resolution imaging. The dynamic inversion method, which can simultaneously use different waves and multi-component observation data, is appropriate for directly inverting elastic parameters, medium density or wave velocities. Full wave-field information is utilized as much as possible at the expense of a larger amount of calculations. To mitigate the computational burden, two ways are proposed to accelerate the method from a computer-implementation point of view. One is source encoding which uses a linear combination of all shots, and the other is to reduce the amount of calculations on forward modeling. We applied a new finite difference method to the dynamic inversion to improve the computational accuracy and speed up the performance. Numerical experiments indicated that the new finite difference method can effectively suppress the numerical dispersion caused by the discretization of wave equations, resulting in enhanced computational efficiency with less memory cost for seismic modeling and inversion based on the full wave equations. We present some inversion results to demonstrate the validity of this method through both checkerboard and Marmousi models. It shows that this method is also convergent even with big deviations for the initial model. Besides, parallel calculations can be

  17. A 181 GOPS AKAZE Accelerator Employing Discrete-Time Cellular Neural Networks for Real-Time Feature Extraction.

    PubMed

    Jiang, Guangli; Liu, Leibo; Zhu, Wenping; Yin, Shouyi; Wei, Shaojun

    2015-01-01

    This paper proposes a real-time feature extraction VLSI architecture for high-resolution images based on the accelerated KAZE algorithm. Firstly, a new system architecture is proposed. It increases the system throughput, provides flexibility in image resolution, and offers trade-offs between speed and scaling robustness. The architecture consists of a two-dimensional pipeline array that fully utilizes computational similarities in octaves. Secondly, a substructure (block-serial discrete-time cellular neural network) that can realize a nonlinear filter is proposed. This structure decreases the memory demand through the removal of data dependency. Thirdly, a hardware-friendly descriptor is introduced in order to overcome the hardware design bottleneck through the polar sample pattern; a simplified method to realize rotation invariance is also presented. Finally, the proposed architecture is designed in TSMC 65 nm CMOS technology. The experimental results show a performance of 127 fps in full HD resolution at 200 MHz frequency. The peak performance reaches 181 GOPS and the throughput is double the speed of other state-of-the-art architectures. PMID:26404305

  18. A 181 GOPS AKAZE Accelerator Employing Discrete-Time Cellular Neural Networks for Real-Time Feature Extraction

    PubMed Central

    Jiang, Guangli; Liu, Leibo; Zhu, Wenping; Yin, Shouyi; Wei, Shaojun

    2015-01-01

    This paper proposes a real-time feature extraction VLSI architecture for high-resolution images based on the accelerated KAZE algorithm. Firstly, a new system architecture is proposed. It increases the system throughput, provides flexibility in image resolution, and offers trade-offs between speed and scaling robustness. The architecture consists of a two-dimensional pipeline array that fully utilizes computational similarities in octaves. Secondly, a substructure (block-serial discrete-time cellular neural network) that can realize a nonlinear filter is proposed. This structure decreases the memory demand through the removal of data dependency. Thirdly, a hardware-friendly descriptor is introduced in order to overcome the hardware design bottleneck through the polar sample pattern; a simplified method to realize rotation invariance is also presented. Finally, the proposed architecture is designed in TSMC 65 nm CMOS technology. The experimental results show a performance of 127 fps in full HD resolution at 200 MHz frequency. The peak performance reaches 181 GOPS and the throughput is double the speed of other state-of-the-art architectures. PMID:26404305

  19. A WiSN node SoC with real-time image compressor and IEEE 802.15.4 MAC accelerator

    NASA Astrophysics Data System (ADS)

    Zhou, Renyan; Liu, Leibo; Yin, Shouyi; Luo, Ao; Chen, Xinkai; Wei, Shaojun

    2014-11-01

    This article presents a wireless image sensor node SoC (system-on-a-chip) for low-power wireless image sensor network (WiSN), in which camera chip interface, high-quality image compression and IEEE 802.15.4 compliant acceleration modules are integrated on chip. The proposed SoC contains a hardware-implemented real-time lossless JPEG (JPEG-LS) compression engine for Bayer Color Filter Arrays (Bayer CFA), reaching a 3.5 bits/pixel with peak signal to noise ratio (PSNR) greater than 46.3 dB and achieving a maximum 5 frames/s @16 MHz for VGA (640 × 480) colour images. The proposed hardware accelerator for IEEE 802.15.4 media access control (MAC) layer covers crucial protocol defined functions and algorithms, and reduces 45% software code in the host processor. This SoC has been fabricated in UMC 0.18 µm 1P6M CMOS process. The average power of the prototype chip is 18.2 mW at 3.0 V power supply and 16 MHz clock rate.

  20. A Bayesian approach to joint analysis of multivariate longitudinal data and parametric accelerated failure time

    PubMed Central

    Luo, Sheng

    2013-01-01

    Impairment caused by Parkinson’s disease (PD) is multidimensional (e.g., sensoria, functions, and cognition) and progressive. Its multidimensional nature precludes a single outcome to measure disease progression. Clinical trials of PD use multiple categorical and continuous longitudinal outcomes to assess the treatment effects on overall improvement. A terminal event such as death or dropout can stop the follow-up process. Moreover, the time to the terminal event may be dependent on the multivariate longitudinal measurements. In this article, we consider a joint random-effects model for the correlated outcomes. A multilevel item response theory model is used for the multivariate longitudinal outcomes and a parametric accelerated failure time model is used for the failure time because of the violation of proportional hazard assumption. These two models are linked via random effects. The Bayesian inference via MCMC is implemented in ‘ BUGS’ language. Our proposed method is evaluated by a simulation study and is applied to DATATOP study, a motivating clinical trial to determine if deprenyl slows the progression of PD. PMID:24009073

  1. A Bayesian approach to joint analysis of multivariate longitudinal data and parametric accelerated failure time.

    PubMed

    Luo, Sheng

    2014-02-20

    Impairment caused by Parkinson's disease (PD) is multidimensional (e.g., sensoria, functions, and cognition) and progressive. Its multidimensional nature precludes a single outcome to measure disease progression. Clinical trials of PD use multiple categorical and continuous longitudinal outcomes to assess the treatment effects on overall improvement. A terminal event such as death or dropout can stop the follow-up process. Moreover, the time to the terminal event may be dependent on the multivariate longitudinal measurements. In this article, we consider a joint random-effects model for the correlated outcomes. A multilevel item response theory model is used for the multivariate longitudinal outcomes and a parametric accelerated failure time model is used for the failure time because of the violation of proportional hazard assumption. These two models are linked via random effects. The Bayesian inference via MCMC is implemented in 'BUGS' language. Our proposed method is evaluated by a simulation study and is applied to DATATOP study, a motivating clinical trial to determine if deprenyl slows the progression of PD. PMID:24009073

  2. The L(1/2) regularization approach for survival analysis in the accelerated failure time model.

    PubMed

    Chai, Hua; Liang, Yong; Liu, Xiao-Ying

    2015-09-01

    The analysis of high-dimensional and low-sample size microarray data for survival analysis of cancer patients is an important problem. It is a huge challenge to select the significantly relevant bio-marks from microarray gene expression datasets, in which the number of genes is far more than the size of samples. In this article, we develop a robust prediction approach for survival time of patient by a L(1/2) regularization estimator with the accelerated failure time (AFT) model. The L(1/2) regularization could be seen as a typical delegate of L(q)(0time of patient based on a set of clinical prognostic factors and gene signatures.

  3. Using precise word timing information improves decoding accuracy in a multiband-accelerated multimodal reading experiment.

    PubMed

    Vu, An T; Phillips, Jeffrey S; Kay, Kendrick; Phillips, Matthew E; Johnson, Matthew R; Shinkareva, Svetlana V; Tubridy, Shannon; Millin, Rachel; Grossman, Murray; Gureckis, Todd; Bhattacharyya, Rajan; Yacoub, Essa

    2016-01-01

    The blood-oxygen-level-dependent (BOLD) signal measured in functional magnetic resonance imaging (fMRI) experiments is generally regarded as sluggish and poorly suited for probing neural function at the rapid timescales involved in sentence comprehension. However, recent studies have shown the value of acquiring data with very short repetition times (TRs), not merely in terms of improvements in contrast to noise ratio (CNR) through averaging, but also in terms of additional fine-grained temporal information. Using multiband-accelerated fMRI, we achieved whole-brain scans at 3-mm resolution with a TR of just 500 ms at both 3T and 7T field strengths. By taking advantage of word timing information, we found that word decoding accuracy across two separate sets of scan sessions improved significantly, with better overall performance at 7T than at 3T. The effect of TR was also investigated; we found that substantial word timing information can be extracted using fast TRs, with diminishing benefits beyond TRs of 1000 ms. PMID:27686111

  4. Using precise word timing information improves decoding accuracy in a multiband-accelerated multimodal reading experiment.

    PubMed

    Vu, An T; Phillips, Jeffrey S; Kay, Kendrick; Phillips, Matthew E; Johnson, Matthew R; Shinkareva, Svetlana V; Tubridy, Shannon; Millin, Rachel; Grossman, Murray; Gureckis, Todd; Bhattacharyya, Rajan; Yacoub, Essa

    2016-01-01

    The blood-oxygen-level-dependent (BOLD) signal measured in functional magnetic resonance imaging (fMRI) experiments is generally regarded as sluggish and poorly suited for probing neural function at the rapid timescales involved in sentence comprehension. However, recent studies have shown the value of acquiring data with very short repetition times (TRs), not merely in terms of improvements in contrast to noise ratio (CNR) through averaging, but also in terms of additional fine-grained temporal information. Using multiband-accelerated fMRI, we achieved whole-brain scans at 3-mm resolution with a TR of just 500 ms at both 3T and 7T field strengths. By taking advantage of word timing information, we found that word decoding accuracy across two separate sets of scan sessions improved significantly, with better overall performance at 7T than at 3T. The effect of TR was also investigated; we found that substantial word timing information can be extracted using fast TRs, with diminishing benefits beyond TRs of 1000 ms.

  5. Solar Energetic Particle Acceleration/Injection Time Profiles: Much Better Observed in the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Roelof, E. C.; Lario, D.; Haggerty, D. K.

    2006-12-01

    We have argued that during the beam-like anisotropic phase of solar energetic particle (SEP) events, the history of the field-aligned unidirectional intensity is essentially that of the injection history at the Sun (shifted backwards by the scatter-free transit time). We have concentrated so far mainly on the injection timing relative to that of solar electromagnetic signatures, because the onset of the first-arriving particles can be delayed by only a fraction of their scatter-free transit time by interplanetary scattering (i.e., 10 min to 1AU for relativistic particles). However, there is much more information than just the onset time contained in the field- aligned intensity time profile throughout the beam-like phase; it must echo that of the actual solar injection history. We have recently classified the intensity time profiles during the duration of the beam-like anisotropies of ACE/EPAM near-relativistic electrons into three broad categories: 1) Spikes (rapid and equal rise and decay); 2) Pulses (rapid rise, slower decay); and 3) Ramps (rapid rise followed by a plateau). These classes indicate a wide range (and possibly different mechanisms) for SEP acceleration/injection. The beam- like anisotropic phase ends when a sufficient number of particles have been backscattered from beyond 1AU where propagation is no longer essentially scatter-free (as it usually is inside 1AU). Preliminary estimates of the time difference between the event beam onset and the first arrival of back-scattered particles yield about 10 min or more. This gives us a 10 min window for an unambiguous view of the injection history (although we can actually extract considerably more of the injection history even in the presence of back-scatter). The >10 min elapsed time for relativistic particles places this back-scattering region somewhere roughly beyond 1.3 AU (a field-aligned round-trip distance of >1.0 beyond 1 AU). Now imagine a spacecraft like one of the Sentinels, Solar Orbiter, or

  6. Guidewire path tracking and segmentation in 2D fluoroscopic time series using device paths from previous frames

    NASA Astrophysics Data System (ADS)

    Wagner, Martin G.; Strother, Charles M.; Mistretta, Charles A.

    2016-03-01

    Recent efforts to perform a 3D reconstruction of interventional devices such as guidewires from monoplane and biplane fluoroscopic images require the segmentation of the exact device path in the respective 2D projection images. The segmentation of the device in low dose fluoroscopy images can be challenging since noise and motion artifacts degrade the image quality. Additionally, extracting the device path from the segmented region may result in ambiguous results due to overlapping device parts or discontinuities in the device segmentation. The purpose of this work is to present a novel guidewire tracking and segmentation algorithm, which segments the device region based on three different features based on a ridge detection filter, noise reduction for curvilinear structures as well as an a priori probability map. The features are calculated from background subtracted as well as unsubtracted fluoroscopic images. The device path extraction is based on a topology preserving thinning algorithm followed by a path search, which minimizes a cost function based on distance and directional difference between adjacent segments as well as the similarity to the device path extracted from the previous frame. The quantitative evaluation was performed using 7 data sets acquired from a canine study. Device shapes with different complexities are compared to semi-automatic segmentations. An average segmentation accuracy of 0.50 0.41 mm was achieved where each point along the device was compared to the point on the reference device centerline with the same distance to the device tip. In all cases the device path could be resolved correctly, which would allow a more accurate and reliable reconstruction of the 3D path of the device.

  7. Picosecond (picoframe) framing camera evaluations.

    PubMed

    Liu, Y; Sibbett, W; Walker, D R

    1992-03-01

    Detailed theoretical evaluations of picoframe-I- and II-type framing cameras are presented, and predicted performance characteristics are compared with experimental results. The methods of theoretical simulations are described, and a suite of computer programs was developed. The theoretical analyses indicate that the existence of fringe fields in the vicinity of the deflectors is the main factor that limits the dynamic spatial resolutions and frame times of these particular designs of framing camera, and possible refinements are outlined. PMID:20720702

  8. TIME-DEPENDENT DIFFUSIVE SHOCK ACCELERATION IN SLOW SUPERNOVA REMNANT SHOCKS

    SciTech Connect

    Tang, Xiaping; Chevalier, Roger A. E-mail: rac5x@virginia.edu

    2015-02-20

    Recent gamma-ray observations show that middle-aged supernova remnants (SNRs) interacting with molecular clouds can be sources of both GeV and TeV emission. Models involving reacceleration of preexisting cosmic rays (CRs) in the ambient medium and direct interaction between SNR and molecular clouds have been proposed to explain the observed gamma-ray emission. For the reacceleration process, standard diffusive shock acceleration (DSA) theory in the test particle limit produces a steady-state particle spectrum that is too flat compared to observations, which suggests that the high-energy part of the observed spectrum has not yet reached a steady state. We derive a time-dependent DSA solution in the test particle limit for situations involving reacceleration of preexisting CRs in the preshock medium. Simple estimates with our time-dependent DSA solution plus a molecular cloud interaction model can reproduce the overall shape of the spectra of IC 443 and W44 from GeV to TeV energies through pure π{sup 0}-decay emission. We allow for a power-law momentum dependence of the diffusion coefficient, finding that a power-law index of 0.5 is favored.

  9. Development of a subway operation incident delay model using accelerated failure time approaches.

    PubMed

    Weng, Jinxian; Zheng, Yang; Yan, Xuedong; Meng, Qiang

    2014-12-01

    This study aims to develop a subway operational incident delay model using the parametric accelerated time failure (AFT) approach. Six parametric AFT models including the log-logistic, lognormal and Weibull models, with fixed and random parameters are built based on the Hong Kong subway operation incident data from 2005 to 2012, respectively. In addition, the Weibull model with gamma heterogeneity is also considered to compare the model performance. The goodness-of-fit test results show that the log-logistic AFT model with random parameters is most suitable for estimating the subway incident delay. First, the results show that a longer subway operation incident delay is highly correlated with the following factors: power cable failure, signal cable failure, turnout communication disruption and crashes involving a casualty. Vehicle failure makes the least impact on the increment of subway operation incident delay. According to these results, several possible measures, such as the use of short-distance and wireless communication technology (e.g., Wifi and Zigbee) are suggested to shorten the delay caused by subway operation incidents. Finally, the temporal transferability test results show that the developed log-logistic AFT model with random parameters is stable over time. PMID:25171521

  10. Multigrid Acceleration of Time-Accurate DNS of Compressible Turbulent Flow

    NASA Technical Reports Server (NTRS)

    Broeze, Jan; Geurts, Bernard; Kuerten, Hans; Streng, Martin

    1996-01-01

    An efficient scheme for the direct numerical simulation of 3D transitional and developed turbulent flow is presented. Explicit and implicit time integration schemes for the compressible Navier-Stokes equations are compared. The nonlinear system resulting from the implicit time discretization is solved with an iterative method and accelerated by the application of a multigrid technique. Since we use central spatial discretizations and no artificial dissipation is added to the equations, the smoothing method is less effective than in the more traditional use of multigrid in steady-state calculations. Therefore, a special prolongation method is needed in order to obtain an effective multigrid method. This simulation scheme was studied in detail for compressible flow over a flat plate. In the laminar regime and in the first stages of turbulent flow the implicit method provides a speed-up of a factor 2 relative to the explicit method on a relatively coarse grid. At increased resolution this speed-up is enhanced correspondingly.

  11. Mediation Analysis with Survival Outcomes: Accelerated Failure Time vs. Proportional Hazards Models

    PubMed Central

    Gelfand, Lois A.; MacKinnon, David P.; DeRubeis, Robert J.; Baraldi, Amanda N.

    2016-01-01

    Objective: Survival time is an important type of outcome variable in treatment research. Currently, limited guidance is available regarding performing mediation analyses with survival outcomes, which generally do not have normally distributed errors, and contain unobserved (censored) events. We present considerations for choosing an approach, using a comparison of semi-parametric proportional hazards (PH) and fully parametric accelerated failure time (AFT) approaches for illustration. Method: We compare PH and AFT models and procedures in their integration into mediation models and review their ability to produce coefficients that estimate causal effects. Using simulation studies modeling Weibull-distributed survival times, we compare statistical properties of mediation analyses incorporating PH and AFT approaches (employing SAS procedures PHREG and LIFEREG, respectively) under varied data conditions, some including censoring. A simulated data set illustrates the findings. Results: AFT models integrate more easily than PH models into mediation models. Furthermore, mediation analyses incorporating LIFEREG produce coefficients that can estimate causal effects, and demonstrate superior statistical properties. Censoring introduces bias in the coefficient estimate representing the treatment effect on outcome—underestimation in LIFEREG, and overestimation in PHREG. With LIFEREG, this bias can be addressed using an alternative estimate obtained from combining other coefficients, whereas this is not possible with PHREG. Conclusions: When Weibull assumptions are not violated, there are compelling advantages to using LIFEREG over PHREG for mediation analyses involving survival-time outcomes. Irrespective of the procedures used, the interpretation of coefficients, effects of censoring on coefficient estimates, and statistical properties should be taken into account when reporting results. PMID:27065906

  12. The framing of drivers' route choices when travel time information is provided under varying degrees of cognitive load.

    PubMed

    Katsikopoulos, K V; Duse-Anthony, Y; Fisher, D L; Duffy, S A

    2000-01-01

    In two experiments, participants chose between staying on a main route with a certain travel time and diverting to an alternative route that could take a range of travel times. In the first experiment, travel time information was displayed on a sheet of paper to participants seated at a desk. In the second experiment, the same information was displayed in a virtual environment through which participants drove. Overall, participants were risk-averse when the average travel time along the alternative route was shorter than the certain travel time of the main route but risk-seeking when the average travel time of the alternative route was longer than the certain travel time along the main route. In the second experiment, in which cognitive load was higher, participants simplified their decision-making strategies. A simple probabilistic model describes the risk-taking behavior and the load effects. Actual or potential applications of this research include the development of efficient travel time information systems for drivers.

  13. Femtosecond timing distribution and control for next generation accelerators and light sources

    SciTech Connect

    Chen, Li -Jin

    2014-03-31

    Femtosecond Timing Distribution At LCLS Free-electron-lasers (FEL) have the capability of producing high photon flux from the IR to the hard x-ray wavelength range and to emit femtosecond and eventually even attosecond pulses. This makes them an ideal tool for fundamental as well as applied re-search. Timing precision at the Stanford Linear Coherent Light Source (LCLS) between the x-ray FEL (XFEL) and ultrafast optical lasers is currently no better than 100 fs RMS. Ideally this precision should be much better and could be limited only by the x-ray pulse duration, which can be as short as a few femtoseconds. An increasing variety of science problems involving electron and nuclear dynamics in chemical and material systems will become accessible as the timing improves to a few femtoseconds. Advanced methods of electron beam conditioning or pulse injection could allow the FEL to achieve pulse durations less than one femtosecond. The objective of the work described in this proposal is to set up an optical timing distribution system based on mode locked Erbium doped fiber lasers at LCLS facility to improve the timing precision in the facility and allow time stamping with a 10 fs precision. The primary commercial applications for optical timing distributions systems are seen in the worldwide accelerator facilities and next generation light sources community. It is reasonable to expect that at least three major XFELs will be built in the next decade. In addition there will be up to 10 smaller machines, such as FERMI in Italy and Maxlab in Sweden, plus the market for upgrading already existing facilities like Jefferson Lab. The total market is estimated to be on the order of a 100 Million US Dollars. The company owns the exclusive rights to the IP covering the technology enabling sub-10 fs synchronization systems. Testing this technology, which has set records in a lab environment, at LCLS, hence in a real world scenario, is an important corner stone of bringing the

  14. Synchronization as a biological, psychological and social mechanism to create common time: A theoretical frame and a single case study.

    PubMed

    Bao, Yan; Pöppel, Ernst; Wang, Lingyan; Lin, Xiaoxiong; Yang, Taoxi; Avram, Mihai; Blautzik, Janusch; Paolini, Marco; Silveira, Sarita; Vedder, Aline; Zaytseva, Yuliya; Zhou, Bin

    2015-12-01

    Synchronizing neural processes, mental activities, and social interactions is considered to be fundamental for the creation of temporal order on the personal and interpersonal level. Several different types of synchronization are distinguished, and for each of them examples are given: self-organized synchronizations on the neural level giving rise to pre-semantically defined time windows of some tens of milliseconds and of approximately 3 s; time windows that are created by synchronizing different neural representations, as for instance in aesthetic appreciations or moral judgments; and synchronization of biological rhythms with geophysical cycles, like the circadian clock with the 24-hr rhythm of day and night. For the latter type of synchronization, an experiment is described that shows the importance of social interactions for sharing or avoiding common time. In a group study with four subjects being completely isolated together for 3 weeks from the external world, social interactions resulted both in intra- and interindividual circadian synchronization and desynchronization. A unique phenomenon in circadian regulation is described, the "beat phenomenon," which has been made visible by the interaction of two circadian rhythms with different frequencies in one body. The separation of the two physiological rhythms was the consequence of social interactions, that is, by the desire of a subject to share and to escape common time during different phases of the long-term experiment. The theoretical arguments on synchronization are summarized with the general statement: "Nothing in cognitive science makes sense except in the light of time windows." The hypothesis is forwarded that time windows that express discrete timing mechanisms in behavioral control and on the level of conscious experiences are the necessary bases to create cognitive order, and it is suggested that time windows are implemented by neural oscillations in different frequency domains. PMID:26663630

  15. Synchronization as a biological, psychological and social mechanism to create common time: A theoretical frame and a single case study.

    PubMed

    Bao, Yan; Pöppel, Ernst; Wang, Lingyan; Lin, Xiaoxiong; Yang, Taoxi; Avram, Mihai; Blautzik, Janusch; Paolini, Marco; Silveira, Sarita; Vedder, Aline; Zaytseva, Yuliya; Zhou, Bin

    2015-12-01

    Synchronizing neural processes, mental activities, and social interactions is considered to be fundamental for the creation of temporal order on the personal and interpersonal level. Several different types of synchronization are distinguished, and for each of them examples are given: self-organized synchronizations on the neural level giving rise to pre-semantically defined time windows of some tens of milliseconds and of approximately 3 s; time windows that are created by synchronizing different neural representations, as for instance in aesthetic appreciations or moral judgments; and synchronization of biological rhythms with geophysical cycles, like the circadian clock with the 24-hr rhythm of day and night. For the latter type of synchronization, an experiment is described that shows the importance of social interactions for sharing or avoiding common time. In a group study with four subjects being completely isolated together for 3 weeks from the external world, social interactions resulted both in intra- and interindividual circadian synchronization and desynchronization. A unique phenomenon in circadian regulation is described, the "beat phenomenon," which has been made visible by the interaction of two circadian rhythms with different frequencies in one body. The separation of the two physiological rhythms was the consequence of social interactions, that is, by the desire of a subject to share and to escape common time during different phases of the long-term experiment. The theoretical arguments on synchronization are summarized with the general statement: "Nothing in cognitive science makes sense except in the light of time windows." The hypothesis is forwarded that time windows that express discrete timing mechanisms in behavioral control and on the level of conscious experiences are the necessary bases to create cognitive order, and it is suggested that time windows are implemented by neural oscillations in different frequency domains.

  16. Real time and accelerated stability studies of Tetanus toxoid manufactured in public sector facilities of Pakistan.

    PubMed

    Parveen, Ghazala; Hussain, Shahzad; Malik, Farnaz; Begum, Anwar; Mahmood, Sidra; Raza, Naeem

    2013-11-01

    Tetanus is an acute illness represented by comprehensive increased inflexibility and spastic spasms of skeletal muscles. The poor quality tetanus toxoid vaccine can raise the prevalence of neonatal tetanus. WHO has taken numerous steps to assist national regulatory authorities and vaccine manufacturers to ensure its quality and efficacy. It has formulated international principles for stability evaluation of each vaccine, which are available in the form of recommendations and guidelines. The aim of present study was to ensure the stability of tetanus vaccines produced by National Institute of Health, Islamabad, Pakistan by employing standardized methods to ensure constancy of tetanus toxoid at elevated temperature, if during storage/transportation cold chain may not be maintained in hot weather. A total of three batches filled during full-scale production were tested. All Stability studies determination were performed on final products stored at 2-8°C and elevated temperatures in conformance with the ICH Guideline of Stability Testing of Biological Products. These studies gave comparison between real time shelf-life stability and accelerated stability studies. The findings indicate long﷓term thermo stability and prove that this tetanus vaccine can remain efficient under setting of routine use when suggested measures for storage and handling are followed in true spirit.

  17. Hamiltonian approach to frame dragging

    NASA Astrophysics Data System (ADS)

    Epstein, Kenneth J.

    2008-07-01

    A Hamiltonian approach makes the phenomenon of frame dragging apparent “up front” from the appearance of the drag velocity in the Hamiltonian of a test particle in an arbitrary metric. Hamiltonian (1) uses the inhomogeneous force equation (4), which applies to non-geodesic motion as well as to geodesics. The Hamiltonian is not in manifestly covariant form, but is covariant because it is derived from Hamilton’s manifestly covariant scalar action principle. A distinction is made between manifest frame dragging such as that in the Kerr metric, and hidden frame dragging that can be made manifest by a coordinate transformation such as that applied to the Robertson-Walker metric in Sect. 2. In Sect. 3 a zone of repulsive gravity is found in the extreme Kerr metric. Section 4 treats frame dragging in special relativity as a manifestation of the equivalence principle in accelerated frames. It answers a question posed by Bell about how the Lorentz contraction can break a thread connecting two uniformly accelerated rocket ships. In Sect. 5 the form of the Hamiltonian facilitates the definition of gravitomagnetic and gravitoelectric potentials.

  18. A time frame permissive for Protein Kinase D2 activity to direct angiogenesis in mouse embryonic stem cells.

    PubMed

    Müller, Martin; Schröer, Jana; Azoitei, Ninel; Eiseler, Tim; Bergmann, Wendy; Köhntop, Ralf; Lin, Qiong; Costa, Ivan G; Zenke, Martin; Genze, Felicitas; Weidgang, Clair; Seufferlein, Thomas; Liebau, Stefan; Kleger, Alexander

    2015-01-01

    The protein kinase D isoenzymes PKD1/2/3 are prominent downstream targets of PKCs (Protein Kinase Cs) and phospholipase D in various biological systems. Recently, we identified PKD isoforms as novel mediators of tumour cell-endothelial cell communication, tumour cell motility and metastasis. Although PKD isoforms have been implicated in physiological/tumour angiogenesis, a role of PKDs during embryonic development, vasculogenesis and angiogenesis still remains elusive. We investigated the role of PKDs in germ layer segregation and subsequent vasculogenesis and angiogenesis using mouse embryonic stem cells (ESCs). We show that mouse ESCs predominantly express PKD2 followed by PKD3 while PKD1 displays negligible levels. Furthermore, we demonstrate that PKD2 is specifically phosphorylated/activated at the time of germ layer segregation. Time-restricted PKD2-activation limits mesendoderm formation and subsequent cardiovasculogenesis during early differentiation while leading to branching angiogenesis during late differentiation. In line, PKD2 loss-of-function analyses showed induction of mesendodermal differentiation in expense of the neuroectodermal germ layer. Our in vivo findings demonstrate that embryoid bodies transplanted on chicken chorioallantoic membrane induced an angiogenic response indicating that timed overexpression of PKD2 from day 4 onwards leads to augmented angiogenesis in differentiating ESCs. Taken together, our results describe novel and time-dependent facets of PKD2 during early cell fate determination. PMID:26148697

  19. A time frame permissive for Protein Kinase D2 activity to direct angiogenesis in mouse embryonic stem cells

    PubMed Central

    Müller, Martin; Schröer, Jana; Azoitei, Ninel; Eiseler, Tim; Bergmann, Wendy; Köhntop, Ralf; Lin, Qiong; Costa, Ivan G; Zenke, Martin; Genze, Felicitas; Weidgang, Clair; Seufferlein, Thomas; Liebau, Stefan; Kleger, Alexander

    2015-01-01

    The protein kinase D isoenzymes PKD1/2/3 are prominent downstream targets of PKCs (Protein Kinase Cs) and phospholipase D in various biological systems. Recently, we identified PKD isoforms as novel mediators of tumour cell-endothelial cell communication, tumour cell motility and metastasis. Although PKD isoforms have been implicated in physiological/tumour angiogenesis, a role of PKDs during embryonic development, vasculogenesis and angiogenesis still remains elusive. We investigated the role of PKDs in germ layer segregation and subsequent vasculogenesis and angiogenesis using mouse embryonic stem cells (ESCs). We show that mouse ESCs predominantly express PKD2 followed by PKD3 while PKD1 displays negligible levels. Furthermore, we demonstrate that PKD2 is specifically phosphorylated/activated at the time of germ layer segregation. Time-restricted PKD2-activation limits mesendoderm formation and subsequent cardiovasculogenesis during early differentiation while leading to branching angiogenesis during late differentiation. In line, PKD2 loss-of-function analyses showed induction of mesendodermal differentiation in expense of the neuroectodermal germ layer. Our in vivo findings demonstrate that embryoid bodies transplanted on chicken chorioallantoic membrane induced an angiogenic response indicating that timed overexpression of PKD2 from day 4 onwards leads to augmented angiogenesis in differentiating ESCs. Taken together, our results describe novel and time-dependent facets of PKD2 during early cell fate determination. PMID:26148697

  20. Athletic Classmates, Physical Self-Concept, and Free-Time Physical Activity: A Longitudinal Study of Frame of Reference Effects

    ERIC Educational Resources Information Center

    Trautwein, Ulrich; Gerlach, Erin; Ludtke, Oliver

    2008-01-01

    The systematic analysis of factors that promote or impede physical activity in children is an urgent task for educational researchers. The present study investigated the reciprocal relationship between physical self-concept, teacher-assigned grades in physical education classes, and free-time physical activity, and analyzed positive and negative…

  1. Short treatment time and excellent treatment outcome in accelerated hyperfractionated radiotherapy for T1 glottic cancer.

    PubMed

    Tamaki, Yukihisa; Hieda, Yoko; Yoshida, Rika; Yoshizako, Takeshi; Fuchiwaki, Takafumi; Aoi, Noriaki; Sekihara, Kazumasa; Kitajima, Kazuhiro; Kawauchi, Hideyuki; Kitagaki, Hajime; Sasaki, Ryohei; Inomata, Taisuke

    2015-11-01

    Accelerated hyperfractionated radiotherapy was performed as treatment for patients with T1 glottic cancer, and its utility was evaluated based on treatment outcomes and adverse effects. Fifty-eight men who had undergone radiotherapy were retrospectively reviewed. Tumor classification was Tis in 4 patients, T1a in 38, and T1b in 16. Histological examination revealed squamous cell carcinoma in 55 patients. Travel time from home to hospital was 0-1 hour for 24 patients, 1-2 hours for 9, and >2 hours for 25. Laser vaporization was performed prior to radiotherapy in 38 patients, and 19 patients received concurrent chemotherapy with an agent such as S-1. Patients were irradiated twice daily using an irradiation container. Most patients received a dose of 1.5 Gy/fraction up to a total of 60 Gy. The median overall treatment time was 30 days, with a median observation period of 59.6 months. A complete response was observed in all patients. The 5-year overall survival, disease-free survival, and local control rates were 97.2%, 93.2%, and 97.8%, respectively. Although grade 3 pharyngeal mucositis was observed in 2 patients, there were no other grade 3 or higher acute adverse events. As late toxicity, grade 2 laryngeal edema and grade 1 laryngeal hemorrhage were observed in 1 patient each, but no serious events such as laryngeal necrosis or laryngeal stenosis were observed. In conclusion, this treatment method brings excellent outcome and will substantially reduce the treatment duration among patients who need to stay at nearby hotels while undergoing treatment at hospitals in rural areas. PMID:26663937

  2. Short treatment time and excellent treatment outcome in accelerated hyperfractionated radiotherapy for T1 glottic cancer

    PubMed Central

    Tamaki, Yukihisa; Hieda, Yoko; Yoshida, Rika; Yoshizako, Takeshi; Fuchiwaki, Takafumi; Aoi, Noriaki; Sekihara, Kazumasa; Kitajima, Kazuhiro; Kawauchi, Hideyuki; Kitagaki, Hajime; Sasaki, Ryohei; Inomata, Taisuke

    2015-01-01

    ABSTRACT Accelerated hyperfractionated radiotherapy was performed as treatment for patients with T1 glottic cancer, and its utility was evaluated based on treatment outcomes and adverse effects. Fifty-eight men who had undergone radiotherapy were retrospectively reviewed. Tumor classification was Tis in 4 patients, T1a in 38, and T1b in 16. Histological examination revealed squamous cell carcinoma in 55 patients. Travel time from home to hospital was 0–1 hour for 24 patients, 1–2 hours for 9, and >2 hours for 25. Laser vaporization was performed prior to radiotherapy in 38 patients, and 19 patients received concurrent chemotherapy with an agent such as S-1. Patients were irradiated twice daily using an irradiation container. Most patients received a dose of 1.5 Gy/fraction up to a total of 60 Gy. The median overall treatment time was 30 days, with a median observation period of 59.6 months. A complete response was observed in all patients. The 5-year overall survival, disease-free survival, and local control rates were 97.2%, 93.2%, and 97.8%, respectively. Although grade 3 pharyngeal mucositis was observed in 2 patients, there were no other grade 3 or higher acute adverse events. As late toxicity, grade 2 laryngeal edema and grade 1 laryngeal hemorrhage were observed in 1 patient each, but no serious events such as laryngeal necrosis or laryngeal stenosis were observed. In conclusion, this treatment method brings excellent outcome and will substantially reduce the treatment duration among patients who need to stay at nearby hotels while undergoing treatment at hospitals in rural areas. PMID:26663937

  3. Effect of frame size and time-on-pasture on steer performance, longissimus muscle fatty acid composition, and tenderness in a forage-finishing system.

    PubMed

    Duckett, S K; Fernandez Rosso, C; Volpi Lagreca, G; Miller, M C; Neel, J P S; Lewis, R M; Swecker, W S; Fontenot, J P

    2014-10-01

    Angus-cross steers (n = 96; BW = 309 ± 34 kg; 13.5 mo of age) were used to determine the effects of frame size (medium or small) and time-on-pasture (TOP) on meat composition and palatability in a 2-yr study. Finishing steers grazed mixed pastures (bluegrass/white clover; April start) and were slaughtered after 89-, 146-, and 201-d TOP. At 24 h postmortem, carcass traits were collected and a rib from each carcass was obtained for proximate and fatty acid composition, Warner-Bratzler shear force (WBSF), and postmortem proteolysis. In yr 1, postmortem aging treatments included 14 and 28 d, whereas in yr 2, postmortem aging treatments included 2, 4, 7, 14, and 28 d. Increasing frame size of the finishing steers produced greater (P < 0.05) ADG by 0.10 kg, BW by 24 kg, HCW by 14 kg, and ribeye size by 2.65 cm(2). All other carcass, meat composition, and tenderness measures did not differ (P > 0.05) due to frame size or 2-way interaction with TOP. Increasing TOP resulted in quadratic increases (P < 0.01) in BW and HCW. Ribeye area, fat thickness, KPH, marbling scores, quality grades, and yield grades increased (P < 0.001) linearly as TOP increased. Time-on-pasture linearly increased (P = 0.001) palmitic (C16:0) acid, oleic (C18:1 cis-9) acid, SFA, and MUFA in the LM. Both n-6 PUFA, linoleic (C18:2) and arachidonic (C20:4) acids, decreased linearly (P = 0.001) with increasing TOP. Increasing TOP linearly reduced (P = 0.01) concentrations of all n-3 fatty acids in the LM. These changes resulted in a linear reduction (P = 0.01) in n-6 to n-3 fatty acid ratio with advancing TOP; however, the magnitude of the difference was small (1.46 vs. 1.37). At 14 d of postmortem aging, WBSF was lowest (P < 0.001) for 89-d TOP and greatest (P < 0.05) for the 201-d TOP. After 28 d of postmortem aging, WBSF values for 89- and 146-d TOP did not differ (P > 0.05) compared to the 14-d postmortem aging WBSF values. However, in steaks from 201-d TOP, additional postmortem aging to 28 d reduced

  4. Examining the limits of time reweighting and Kramers' rate theory to obtain correct kinetics from accelerated molecular dynamics.

    PubMed

    Xin, Yao; Doshi, Urmi; Hamelberg, Donald

    2010-06-14

    Accelerated molecular dynamics simulations are routinely being used to recover the correct canonical probability distributions corresponding to the original potential energy landscape of biomolecular systems. However, the limits of time reweighting, based on transition state theory, in obtaining true kinetic rates from accelerated molecular dynamics for biomolecular systems are less obvious. Here, we investigate this issue by studying the kinetics of cis-trans isomerization of peptidic omega bond by accelerated molecular dynamics. We find that time reweighting is valid for obtaining true kinetics when the original potential is not altered at the transition state regions, as expected. When the original potential landscape is modified such that the applied boost potential alters the transition state regions, time reweighting fails to reproduce correct kinetics and the reweighted rate is much slower than the true rate. By adopting the overdamped limit of Kramers' rate theory, we are successful in recovering correct kinetics irrespective of whether or not the transition state regions are modified. Furthermore, we tested the validity of the acceleration weight factor from the path integral formalism for obtaining the correct kinetics of cis-trans isomerization. It was found that this formulation of the weight factor is not suitable for long time scale processes such as cis-trans isomerization with high energy barriers.

  5. A simple approach to estimate earthquake magnitude from the arrival time of the peak acceleration amplitude

    NASA Astrophysics Data System (ADS)

    Noda, S.; Yamamoto, S.

    2014-12-01

    In order for Earthquake Early Warning (EEW) to be effective, the rapid determination of magnitude (M) is important. At present, there are no methods which can accurately determine M even for extremely large events (ELE) for EEW, although a number of the methods have been suggested. In order to solve the problem, we use a simple approach derived from the fact that the time difference (Top) from the onset of the body wave to the arrival time of the peak acceleration amplitude of the body wave scales with M. To test this approach, we use 15,172 accelerograms of regional earthquakes (most of them are M4-7 events) from the K-NET, as the first step. Top is defined by analyzing the S-wave in this step. The S-onsets are calculated by adding the theoretical S-P times to the P-onsets which are manually picked. As the result, it is confirmed that logTop has high correlation with Mw, especially for the higher frequency band (> 2Hz). The RMS of residuals between Mw and M estimated in this step is less than 0.5. In case of the 2011 Tohoku earthquake, M is estimated to be 9.01 at 150 seconds after the initiation of the event.To increase the number of the ELE data, we add the teleseismic high frequency P-wave records to the analysis, as the second step. According to the result of various back-projection analyses, we consider the teleseismic P-waves to contain information on the entire rupture process. The BHZ channel data of the Global Seismographic Network for 24 events are used in this step. 2-4Hz data from the stations in the epicentral distance range of 30-85 degrees are used following the method of Hara [2007]. All P-onsets are manually picked. Top obtained from the teleseimic data show good correlation with Mw, complementing the one obtained from the regional data. We conclude that the proposed approach is quite useful for estimating reliable M for EEW, even for the ELE.

  6. HEART Pathway Accelerated Diagnostic Protocol Implementation: Prospective Pre-Post Interrupted Time Series Design and Methods

    PubMed Central

    Wells, Brian J

    2016-01-01

    Background Most patients presenting to US Emergency Departments (ED) with chest pain are hospitalized for comprehensive testing. These evaluations cost the US health system >$10 billion annually, but have a diagnostic yield for acute coronary syndrome (ACS) of <10%. The history/ECG/age/risk factors/troponin (HEART) Pathway is an accelerated diagnostic protocol (ADP), designed to improve care for patients with acute chest pain by identifying patients for early ED discharge. Prior efficacy studies demonstrate that the HEART Pathway safely reduces cardiac testing, while maintaining an acceptably low adverse event rate. Objective The purpose of this study is to determine the effectiveness of HEART Pathway ADP implementation within a health system. Methods This controlled before-after study will accrue adult patients with acute chest pain, but without ST-segment elevation myocardial infarction on electrocardiogram for two years and is expected to include approximately 10,000 patients. Outcomes measures include hospitalization rate, objective cardiac testing rates (stress testing and angiography), length of stay, and rates of recurrent cardiac care for participants. Results In pilot data, the HEART Pathway decreased hospitalizations by 21%, decreased hospital length (median of 12 hour reduction), without increasing adverse events or recurrent care. At the writing of this paper, data has been collected on >5000 patient encounters. The HEART Pathway has been fully integrated into health system electronic medical records, providing real-time decision support to our providers. Conclusions We hypothesize that the HEART Pathway will safely reduce healthcare utilization. This study could provide a model for delivering high-value care to the 8-10 million US ED patients with acute chest pain each year. ClinicalTrial Clinicaltrials.gov NCT02056964; https://clinicaltrials.gov/ct2/show/NCT02056964 (Archived by WebCite at http://www.webcitation.org/6ccajsgyu) PMID:26800789

  7. Singular F(R) cosmology unifying early- and late-time acceleration with matter and radiation domination era

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-06-01

    We present some cosmological models which unify the late- and early-time acceleration eras with the radiation and the matter domination era, and we realize the cosmological models by using the theoretical framework of F(R) gravity. Particularly, the first model unifies the late- and early-time acceleration with the matter domination era, and the second model unifies all the evolution eras of our Universe. The two models are described in the same way at early and late times, and only the intermediate stages of the evolution have some differences. Each cosmological model contains two Type IV singularities which are chosen to occur one at the end of the inflationary era and one at the end of the matter domination era. The cosmological models at early times are approximately identical to the R 2 inflation model, so these describe a slow-roll inflationary era which ends when the slow-roll parameters become of order one. The inflationary era is followed by the radiation era and after that the matter domination era follows, which lasts until the second Type IV singularity, and then the late-time acceleration era follows. The models have two appealing features: firstly they produce a nearly scale invariant power spectrum of primordial curvature perturbations and a scalar-to-tensor ratio which are compatible with the most recent observational data and secondly, it seems that the deceleration–acceleration transition is crucially affected by the presence of the second Type IV singularity which occurs at the end of the matter domination era. As we demonstrate, the Hubble horizon at early times shrinks, as expected for an initially accelerating Universe, then during the matter domination era, it expands and finally after the Type IV singularity, the Hubble horizon starts to shrink again, during the late-time acceleration era. Intriguingly enough, the deceleration–acceleration transition, occurs after the second Type IV singularity. In addition, we investigate which F

  8. Singular F(R) cosmology unifying early- and late-time acceleration with matter and radiation domination era

    NASA Astrophysics Data System (ADS)

    Odintsov, S. D.; Oikonomou, V. K.

    2016-06-01

    We present some cosmological models which unify the late- and early-time acceleration eras with the radiation and the matter domination era, and we realize the cosmological models by using the theoretical framework of F(R) gravity. Particularly, the first model unifies the late- and early-time acceleration with the matter domination era, and the second model unifies all the evolution eras of our Universe. The two models are described in the same way at early and late times, and only the intermediate stages of the evolution have some differences. Each cosmological model contains two Type IV singularities which are chosen to occur one at the end of the inflationary era and one at the end of the matter domination era. The cosmological models at early times are approximately identical to the R 2 inflation model, so these describe a slow-roll inflationary era which ends when the slow-roll parameters become of order one. The inflationary era is followed by the radiation era and after that the matter domination era follows, which lasts until the second Type IV singularity, and then the late-time acceleration era follows. The models have two appealing features: firstly they produce a nearly scale invariant power spectrum of primordial curvature perturbations and a scalar-to-tensor ratio which are compatible with the most recent observational data and secondly, it seems that the deceleration-acceleration transition is crucially affected by the presence of the second Type IV singularity which occurs at the end of the matter domination era. As we demonstrate, the Hubble horizon at early times shrinks, as expected for an initially accelerating Universe, then during the matter domination era, it expands and finally after the Type IV singularity, the Hubble horizon starts to shrink again, during the late-time acceleration era. Intriguingly enough, the deceleration-acceleration transition, occurs after the second Type IV singularity. In addition, we investigate which F(R) gravity

  9. The time-frame of acute resistance exercise effects on football skill performance: the impact of exercise intensity.

    PubMed

    Draganidis, Dimitrios; Chatzinikolaou, Athanasios; Jamurtas, Athanasios Z; Carlos Barbero, Jose; Tsoukas, Dimitrios; Theodorou, Apostolos Spyridon; Margonis, Konstantinos; Michailidis, Yannis; Avloniti, Alexandra; Theodorou, Anastasios; Kambas, Antonis; Fatouros, Ioannis

    2013-01-01

    The purpose of this study was to determine the recovery rate of football skill performance following resistance exercise of moderate or high intensity. Ten elite football players participated in three different trials: control, low-intensity resistance exercise (4 sets, 8-10 repetitions/set, 65-70% 1 repetition maximum [1RM]) and high-intensity resistance exercise (4 sets, 4-6 repetitions/set, 85-90% 1RM) in a counterbalanced manner. In each experimental condition, participants were evaluated pre, post, and at 24, 48, 72 h post exercise time points. Football skill performance was assessed through the Loughborough Soccer Passing Test, long passing, dribbling, shooting and heading. Delayed onset muscle soreness, knee joint range of motion, and muscle strength (1RM) in squat were considered as muscle damage markers. Blood samples analysed for creatine kinase activity, C-reactive protein, and leukocyte count. Passing and shooting performance declined (P < 0.05) post-exercise following resistance exercise. Strength declined post-exercise following high-intensity resistance exercise. Both trials induced only a mild muscle damage and inflammatory response in an intensity-dependent manner. These results indicate that football skill performance is minimally affected by acute resistance exercise independent of intensity suggesting that elite players may be able to participate in a football practice or match after only 24 h following a strength training session. PMID:23301779

  10. The time-frame of acute resistance exercise effects on football skill performance: the impact of exercise intensity.

    PubMed

    Draganidis, Dimitrios; Chatzinikolaou, Athanasios; Jamurtas, Athanasios Z; Carlos Barbero, Jose; Tsoukas, Dimitrios; Theodorou, Apostolos Spyridon; Margonis, Konstantinos; Michailidis, Yannis; Avloniti, Alexandra; Theodorou, Anastasios; Kambas, Antonis; Fatouros, Ioannis

    2013-01-01

    The purpose of this study was to determine the recovery rate of football skill performance following resistance exercise of moderate or high intensity. Ten elite football players participated in three different trials: control, low-intensity resistance exercise (4 sets, 8-10 repetitions/set, 65-70% 1 repetition maximum [1RM]) and high-intensity resistance exercise (4 sets, 4-6 repetitions/set, 85-90% 1RM) in a counterbalanced manner. In each experimental condition, participants were evaluated pre, post, and at 24, 48, 72 h post exercise time points. Football skill performance was assessed through the Loughborough Soccer Passing Test, long passing, dribbling, shooting and heading. Delayed onset muscle soreness, knee joint range of motion, and muscle strength (1RM) in squat were considered as muscle damage markers. Blood samples analysed for creatine kinase activity, C-reactive protein, and leukocyte count. Passing and shooting performance declined (P < 0.05) post-exercise following resistance exercise. Strength declined post-exercise following high-intensity resistance exercise. Both trials induced only a mild muscle damage and inflammatory response in an intensity-dependent manner. These results indicate that football skill performance is minimally affected by acute resistance exercise independent of intensity suggesting that elite players may be able to participate in a football practice or match after only 24 h following a strength training session.

  11. Real-time cardiac synchronization with fixed volume frame rate for reducing physiological instabilities in 3D FMRI.

    PubMed

    Tijssen, Rob H N; Okell, Thomas W; Miller, Karla L

    2011-08-15

    Although 2D echo-planar imaging (EPI) remains the dominant method for functional MRI (FMRI), 3D readouts are receiving more interest as these sequences have favorable signal-to-noise ratio (SNR) and enable imaging at a high isotropic resolution. Spoiled gradient-echo (SPGR) and balanced steady-state free-precession (bSSFP) are rapid sequences that are typically acquired with highly segmented 3D readouts, and thus less sensitive to image distortion and signal dropout. They therefore provide a powerful alternative for FMRI in areas with strong susceptibility offsets, such as deep gray matter structures and the brainstem. Unfortunately, the multi-shot nature of the readout makes these sequences highly sensitive to physiological fluctuations, and large signal instabilities are observed in the inferior regions of the brain. In this work a characterization of the source of these instabilities is given and a new method is presented to reduce the instabilities observed in 3D SPGR and bSSFP. Rapidly acquired single-slice data, which critically sampled the respiratory and cardiac waveforms, showed that cardiac pulsation is the dominant source of the instabilities. Simulations further showed that synchronizing the readout to the cardiac cycle minimizes the instabilities considerably. A real-time synchronization method was therefore developed, which utilizes parallel-imaging techniques to allow cardiac synchronization without alteration of the volume acquisition rate. The implemented method significantly improves the temporal stability in areas that are affected by cardiac-related signal fluctuations. In bSSFP data the tSNR in the brainstem increased by 45%, at the cost of a small reduction in tSNR in the cortical areas. In SPGR the temporal stability is improved by approximately 20% in the subcortical structures and as well as cortical gray matter when synchronization was performed.

  12. Analysis on the Time and Frequency Domains of the Acceleration in Front Crawl Stroke

    PubMed Central

    Gil, Joaquín Madera; Moreno, Luis-Millán González; Mahiques, Juan Benavent; Muñoz, Víctor Tella

    2012-01-01

    The swimming involves accelerations and decelerations in the swimmer’s body. Thus, the main objective of this study is to make a temporal and frequency analysis of the acceleration in front crawl swimming, regarding the gender and the performance. The sample was composed by 31 male swimmers (15 of high-level and 16 of low-level) and 20 female swimmers (11 of high-level and 9 of low-level). The acceleration was registered from the third complete cycle during eight seconds in a 25 meters maximum velocity test. A position transducer (200Hz) was used to collect the data, and it was synchronized to an aquatic camera (25Hz). The acceleration in the temporal (root mean square, minimum and maximum of the acceleration) and frequency (power peak, power peak frequency and spectral area) domains was calculated with Fourier analysis, as well as the velocity and the spectrums distribution in function to present one or more main peaks (type 1 and type 2). A one-way ANOVA was used to establish differences between gender and performance. Results show differences between genders in all the temporal domain variables (p<0.05) and only the Spectral Area (SA) in the frequency domain (p<0.05). Between gender and performance, only the Root Mean Square (RMS) showed differences in the performance of the male swimmers (p<0.05) and in the higher level swimmers, the Maximum (Max) and the Power Peak (PP) of the acceleration showed differences between both genders (p<0.05). These results confirms the importance of knowing the RMS to determine the efficiency of the swimmers regarding gender and performance level PMID:23487001

  13. An Experiment in ''Less Time, More Options": A Study of Accelerated University Students.

    ERIC Educational Resources Information Center

    Litwin, James L.; And Others

    This study investigated the characteristics and experiences of 59 college students accelerated from their freshman to their junior year. The students showed high academic performance and few social problems, but questions of personal identity remained problematic; the best single predictor of academic success was found to be freshman grade-point…

  14. Deformed phase space Kaluza-Klein cosmology and late time acceleration

    NASA Astrophysics Data System (ADS)

    Sabido, M.; Yee-Romero, C.

    2016-06-01

    The effects of phase space deformations on Kaluza-Klein cosmology are studied. The deformation is introduced by modifying the symplectic structure of the minisuperspace variables. In the deformed model, we find an accelerating scale factor and therefore infer the existence of an effective cosmological constant from the phase space deformation parameter β.

  15. An Investigation On The Problems Of The Intermittent High-Speed Camera Of 360 Frames/S

    NASA Astrophysics Data System (ADS)

    Zhihong, Rong

    1989-06-01

    This paper discusses several problems on the JX-300 intermittent synchronous high-speed camera developed by the Institue of Optics and Electronics (10E), Academia Sinica in 1985. It is shown that when a framing rate is no more than 120 frames/s, a relatively high reliability is obtained resulting from low acceleration of the moving elements, weak intermittent pulldown strength, low frequency vibration, etc. At the time when a framing rate increases to over 200 frames/s, the photographic resolving power, as well as the film running reliability reduce due to the dramatic increase in vibration and pulldown strenth, which is similar to that in the stationary photography. It is getting worse when the framing rate is up to 300 frames/s. Therefore, deliberating on the choice of a claw mechanism having a framing rate of over 300 frames/s and conducting a series of technical measures are particularly important for a camera to obtain a sharp object image securely, otherwise it can hardly reach the framing rate of 300 frames/s for an intermittent camera. Even if this framing rate is attained, the image quality is also deformed and the mechanism would be rapidly worn off from high vibration.

  16. Quasi-gravitational Effect in the Accelerating Universe

    NASA Astrophysics Data System (ADS)

    Harutyunian, H. A.

    2016-09-01

    The possibility of measuring of the accelerated expansion rate at any point of our Universe is considered. It is argued that as the only reference frame in the Universe expanding with acceleration can serve the cosmological horizon - the most distant sphere belonging the observable Universe. All the points of this sphere represent the initial point coincided with the observer's local point at the beginning of time. And at the present the observer moves away from all that points. Simple calculations show that the acceleration of the observer with respect to the cosmological horizon is very small and numerically equal to the Pioneers' anomalous acceleration.

  17. Estimating time to contact and impact velocity when catching an accelerating object with the hand.

    PubMed

    Senot, Patrice; Prévost, Pascal; McIntyre, Joseph

    2003-02-01

    To catch a moving object with the hand requires precise coordination between visual information about the target's motion and the muscle activity necessary to prepare for the impact. A key question remains open as to if and how a human observer uses velocity and acceleration information when controlling muscles in anticipation of impact. Participants were asked to catch the moving end of a swinging counterweighted pendulum, and resulting muscle activities in the arm were measured. The authors also simulated muscle activities that would be produced according to different tuning strategies. By comparing data with simulations, the authors provide evidence that human observers use online information about velocity but not acceleration when preparing for impact.

  18. Development of a Nomarski-type multi-frame interferometer as a time and space resolving diagnostics for the free electron density of laser-generated plasma

    SciTech Connect

    Boerner, M.; Frank, A.; Pelka, A.; Schaumann, G.; Schoekel, A.; Schumacher, D.; Roth, M.; Fils, J.; Blazevic, A.; Hessling, T.; Basko, M. M.; Maruhn, J.; Tauschwitz, An.

    2012-04-15

    This article reports on the development and set-up of a Nomarski-type multi-frame interferometer as a time and space resolving diagnostics of the free electron density in laser-generated plasma. The interferometer allows the recording of a series of 4 images within 6 ns of a single laser-plasma interaction. For the setup presented here, the minimal accessible free electron density is 5 x 10{sup 18} cm{sup -3}, the maximal one is 2 x 10{sup 20} cm{sup -3}. Furthermore, it provides a resolution of the electron density in space of 50 {mu}m and in time of 0.5 ns for one image with a customizable magnification in space for each of the 4 images. The electron density was evaluated from the interferograms using an Abel inversion algorithm. The functionality of the system was proven during first experiments and the experimental results are presented and discussed. A ray tracing procedure was realized to verify the interferometry pictures taken. In particular, the experimental results are compared to simulations and show excellent agreement, providing a conclusive picture of the evolution of the electron density distribution.

  19. Instability of multi-layer fluid configurations in the presence of time-dependent accelerations in a microgravity environment

    NASA Technical Reports Server (NTRS)

    Lyell, M. J.; Roh, Michael

    1991-01-01

    The increasing number of research opportunities in a microgravity environment will benefit not only fundamental studies in fluid dynamics, but also technological applications such as those involving materials processing. In particular, fluid configurations which involve fluid-fluid interfaces would occur in a variety of experimental investigations. This work investigates the stability of a configuration involving fluid-fluid interfaces in the presence of a time-dependent forcing. Both periodic (g-jitter) and nonperiodic accelerations are considered. The fluid configuration is multilayered, and infinite in extent. The analysis is linear and inviscid, and the acceleration vector is oriented perpendicular to each interface. A Floquet analysis is employed in the case of the periodic forcing. In the problem of nonperiodic forcing, the resulting system of equations are integrated in time. Specific nondimensional parameters appear in each problem. The configuration behavior is investigated for a range of parameter values.

  20. Thirty Frames per Second

    ERIC Educational Resources Information Center

    Kelly, Bruce

    2006-01-01

    Analyzing real motion with frame-by-frame precision can be conducted using modestly priced digital-video camcorders. Although well below the 1,000 frames-per-second threshold of high-speed cameras, commercially available camcorders grab 30 frames per second. A replay dissected at this lower frequency is fun to watch, challenges students'…

  1. Evolution of the single-mode Rayleigh-Taylor instability under the influence of time-dependent accelerations.

    PubMed

    Ramaprabhu, P; Karkhanis, V; Banerjee, R; Varshochi, H; Khan, M; Lawrie, A G W

    2016-01-01

    From nonlinear models and direct numerical simulations we report on several findings of relevance to the single-mode Rayleigh-Taylor (RT) instability driven by time-varying acceleration histories. The incompressible, direct numerical simulations (DNSs) were performed in two (2D) and three dimensions (3D), and at a range of density ratios of the fluid combinations (characterized by the Atwood number). We investigated several acceleration histories, including acceleration profiles of the general form g(t)∼t^{n}, with n≥0 and acceleration histories reminiscent of the linear electric motor experiments. For the 2D flow, results from numerical simulations compare well with a 2D potential flow model and solutions to a drag-buoyancy model reported as part of this work. When the simulations are extended to three dimensions, bubble and spike growth rates are in agreement with the so-called level 2 and level 3 models of Mikaelian [K. O. Mikaelian, Phys. Rev. E 79, 065303(R) (2009)10.1103/PhysRevE.79.065303], and with corresponding 3D drag-buoyancy model solutions derived in this article. Our generalization of the RT problem to study variable g(t) affords us the opportunity to investigate the appropriate scaling for bubble and spike amplitudes under these conditions. We consider two candidates, the displacement Z and width s^{2}, but find the appropriate scaling is dependent on the density ratios between the fluids-at low density ratios, bubble and spike amplitudes are explained by both s^{2} and Z, while at large density differences the displacement collapses the spike data. Finally, for all the acceleration profiles studied here, spikes enter a free-fall regime at lower Atwood numbers than predicted by all the models. PMID:26871165

  2. Evolution of the single-mode Rayleigh-Taylor instability under the influence of time-dependent accelerations

    NASA Astrophysics Data System (ADS)

    Ramaprabhu, P.; Karkhanis, V.; Banerjee, R.; Varshochi, H.; Khan, M.; Lawrie, A. G. W.

    2016-01-01

    From nonlinear models and direct numerical simulations we report on several findings of relevance to the single-mode Rayleigh-Taylor (RT) instability driven by time-varying acceleration histories. The incompressible, direct numerical simulations (DNSs) were performed in two (2D) and three dimensions (3D), and at a range of density ratios of the fluid combinations (characterized by the Atwood number). We investigated several acceleration histories, including acceleration profiles of the general form g (t ) ˜tn , with n ≥0 and acceleration histories reminiscent of the linear electric motor experiments. For the 2D flow, results from numerical simulations compare well with a 2D potential flow model and solutions to a drag-buoyancy model reported as part of this work. When the simulations are extended to three dimensions, bubble and spike growth rates are in agreement with the so-called level 2 and level 3 models of Mikaelian [K. O. Mikaelian, Phys. Rev. E 79, 065303(R) (2009), 10.1103/PhysRevE.79.065303], and with corresponding 3D drag-buoyancy model solutions derived in this article. Our generalization of the RT problem to study variable g (t ) affords us the opportunity to investigate the appropriate scaling for bubble and spike amplitudes under these conditions. We consider two candidates, the displacement Z and width s2, but find the appropriate scaling is dependent on the density ratios between the fluids—at low density ratios, bubble and spike amplitudes are explained by both s2 and Z , while at large density differences the displacement collapses the spike data. Finally, for all the acceleration profiles studied here, spikes enter a free-fall regime at lower Atwood numbers than predicted by all the models.

  3. Evolution of the single-mode Rayleigh-Taylor instability under the influence of time-dependent accelerations.

    PubMed

    Ramaprabhu, P; Karkhanis, V; Banerjee, R; Varshochi, H; Khan, M; Lawrie, A G W

    2016-01-01

    From nonlinear models and direct numerical simulations we report on several findings of relevance to the single-mode Rayleigh-Taylor (RT) instability driven by time-varying acceleration histories. The incompressible, direct numerical simulations (DNSs) were performed in two (2D) and three dimensions (3D), and at a range of density ratios of the fluid combinations (characterized by the Atwood number). We investigated several acceleration histories, including acceleration profiles of the general form g(t)∼t^{n}, with n≥0 and acceleration histories reminiscent of the linear electric motor experiments. For the 2D flow, results from numerical simulations compare well with a 2D potential flow model and solutions to a drag-buoyancy model reported as part of this work. When the simulations are extended to three dimensions, bubble and spike growth rates are in agreement with the so-called level 2 and level 3 models of Mikaelian [K. O. Mikaelian, Phys. Rev. E 79, 065303(R) (2009)10.1103/PhysRevE.79.065303], and with corresponding 3D drag-buoyancy model solutions derived in this article. Our generalization of the RT problem to study variable g(t) affords us the opportunity to investigate the appropriate scaling for bubble and spike amplitudes under these conditions. We consider two candidates, the displacement Z and width s^{2}, but find the appropriate scaling is dependent on the density ratios between the fluids-at low density ratios, bubble and spike amplitudes are explained by both s^{2} and Z, while at large density differences the displacement collapses the spike data. Finally, for all the acceleration profiles studied here, spikes enter a free-fall regime at lower Atwood numbers than predicted by all the models.

  4. New Features of Time Domain Electric-Field Structures in the Auroral Acceleration Region

    SciTech Connect

    Mozer, F.S.; Ergun, R.; Temerin, M.; Cattell, C.; Dombeck, J.; Wygant, J.

    1997-08-01

    The Polar Satellite carries the first three-axis electric field detector flown in the magnetosphere. Its direct measurement of electric field components perpendicular and parallel to the local magnetic field has revealed new classes and features of electric field structures associated with the plasma acceleration that produces discrete auroras and that populates the magnetosphere with plasma of ionospheric origin. These structures, associated with the hydrogen ion cyclotron mode, include very large solitary waves, spiky field structures, wave envelopes of parallel electric fields, and very large amplitude, nonlinear, coherent ion cyclotron waves. {copyright} {ital 1997} {ital The American Physical Society}

  5. A greigite-based magnetostratigraphic time frame for the Late Miocene to Recent DSDP Leg 42B cores from the Black Sea

    NASA Astrophysics Data System (ADS)

    Van Baak, Christiaan; Vasiliev, Iuliana; Palcu, Dan; Dekkers, Mark; Krijgsman, Wout

    2016-05-01

    Throughout the Late Neogene, the Black Sea experienced large paleoenvironmental changes, switching between (anoxic) marine conditions when connected to the Mediterranean Sea and (oxic) freshwater conditions at times of isolation. We create a magnetostratigraphic time frame for three sites drilled during Deep Sea Drilling Project (DSDP) Leg 42B to the Black Sea (drilled in 1975). At the time, magnetostratigraphic dating was impossible because of the presence of the little understood iron sulfide mineral greigite (in sediments a precursor to pyrite) as magnetic carrier. Our rock-magnetic results indicate that only anoxic conditions result in poor magnetic signal, likely as a result of pyrite formation in the water column rather than in the sediment. The magnetostratigraphic results indicate that Hole 379A, drilled in the basin center, has a continuous sedimentary record dating back to 1.3 Ma. Hole 380/380A is subdivided into three consistent intervals, 0-700 mbsf, 700-860 mbsf and 860-1075 mbsf. The top unit covers the Pleistocene but the magnetostratigraphy is likely compromised by the presence of mass transport deposits. The middle unit spans between 4.3 and 6.1 Ma and records continuous deposition at ~10 cm/kyr. The lower unit lacks the independent age constraints to correlate the obtained magnetostratigraphy. Hole 381 is drilled on the Bosporus slope and as a result, hiatuses are common. A correlation to the nearby Hole 380/380A is proposed, but indicates deposits cannot straightforwardly be traced across the slope. Our improved age model does not support the original interpretation based on these cores of a desiccation of the Black Sea during the Messinian salinity crisis.

  6. Short Time Impulse Response Function (STIRF) for automatic evaluation of the variation of the dynamic parameters of reinforced concrete framed structures during strong earthquakes.

    NASA Astrophysics Data System (ADS)

    Carlo Ponzo, Felice; Ditommaso, Rocco

    2015-04-01

    the results provided in this study, the methodology seems to be able to evaluate fast variations (over time) of dynamic parameters of a generic reinforced concrete framed structure. Further analyses are necessary to better calibrate the length of the moving time-window (in order to minimize the spurious frequency within each Interferometric Response Function evaluated on both weak and strong motion phases) and to verify the possibility to use the STIRF to analyse the nonlinear behaviour of general systems. Acknowledgements This study was partially funded by the Italian Civil Protection Department within the project DPC-RELUIS 2014 - RS4 ''Seismic observatory of structures and health monitoring''. References R. Ditommaso, F.C. Ponzo (2015). Automatic evaluation of the fundamental frequency variations and related damping factor of reinforced concrete framed structures using the Short Time Impulse Response Function (STIRF). Engineering Structures, 82 (2015), 104-112. http://dx.doi.org/10.1016/j.engstruct.2014.10.023.

  7. Ten scenarios from early radiation to late time acceleration with a minimally coupled dark energy

    SciTech Connect

    Fay, Stéphane

    2013-09-01

    We consider General Relativity with matter, radiation and a minimally coupled dark energy defined by an equation of state w. Using dynamical system method, we find the equilibrium points of such a theory assuming an expanding Universe and a positive dark energy density. Two of these points correspond to classical radiation and matter dominated epochs for the Universe. For the other points, dark energy mimics matter, radiation or accelerates Universe expansion. We then look for possible sequences of epochs describing a Universe starting with some radiation dominated epoch(s) (mimicked or not by dark energy), then matter dominated epoch(s) (mimicked or not by dark energy) and ending with an accelerated expansion. We find ten sequences able to follow this Universe history without singular behaviour of w at some saddle points. Most of them are new in dark energy literature. To get more than these ten sequences, w has to be singular at some specific saddle equilibrium points. This is an unusual mathematical property of the equation of state in dark energy literature, whose physical consequences tend to be discarded by observations. This thus distinguishes the ten above sequences from an infinity of ways to describe Universe expansion.

  8. Rovibrational spectroscopy using a kinetic energy operator in Eckart frame and the multi-configuration time-dependent Hartree (MCTDH) approach

    SciTech Connect

    Sadri, Keyvan Meyer, Hans-Dieter; Lauvergnat, David; Gatti, Fabien

    2014-09-21

    For computational rovibrational spectroscopy the choice of the frame is critical for an approximate separation of overall rotation from internal motions. To minimize the coupling between internal coordinates and rotation, Eckart proposed a condition [“Some studies concerning rotating axes and polyatomic molecules,” Phys. Rev. 47, 552–558 (1935)] and a frame that fulfills this condition is hence called an Eckart frame. A method is developed to introduce in a systematic way the Eckart frame for the expression of the kinetic energy operator (KEO) in the polyspherical approach. The computed energy levels of a water molecule are compared with those obtained using a KEO in the standard definition of the Body-fixed frame of the polyspherical approach. The KEO in the Eckart frame leads to a faster convergence especially for large J states and vibrationally excited states. To provide an example with more degrees of freedom, rotational states of the vibrational ground state of the trans nitrous acid (HONO) are also investigated.

  9. Real-time dedispersion for fast radio transient surveys, using auto tuning on many-core accelerators

    NASA Astrophysics Data System (ADS)

    Sclocco, A.; van Leeuwen, J.; Bal, H. E.; van Nieuwpoort, R. V.

    2016-01-01

    Dedispersion, the removal of deleterious smearing of impulsive signals by the interstellar matter, is one of the most intensive processing steps in any radio survey for pulsars and fast transients. We here present a study of the parallelization of this algorithm on many-core accelerators, including GPUs from AMD and NVIDIA, and the Intel Xeon Phi. We find that dedispersion is inherently memory-bound. Even in a perfect scenario, hardware limitations keep the arithmetic intensity low, thus limiting performance. We next exploit auto-tuning to adapt dedispersion to different accelerators, observations, and even telescopes. We demonstrate that the optimal settings differ between observational setups, and that auto-tuning significantly improves performance. This impacts time-domain surveys from Apertif to SKA.

  10. On the acceleration of ions by interplanetary shock waves. 3: High time resolution observations of CIR proton events

    NASA Technical Reports Server (NTRS)

    Pesses, M. E.; Vanallen, J. A.; Tsurutani, B. T.; Smith, E. J.

    1981-01-01

    Observations within + or - 3 hours of corotating interaction region (CIR) shock waves of proton intensities, pitch angle distribution and crude differential energy spectra of the range of 0.6 E sub p 3.4 MeV are presented. The principle result is the evidence for the persistent flow of particles away from the shock. The observations are found to be in good agreement with the hypothesis of local interplanetary shock acceleration by the shock drift and compression mechanisms. The same set of observations strongly suggest that transit time damping does not play an important role in the acceleration of protons to 1 MeV in the immediate vicinity of CIR shocks.

  11. Evaluation of the Effectiveness of the Stereotactic Body Frame in Reducing Respiratory Intrafractional Organ Motion Using the Real-Time Tumor-Tracking Radiotherapy System

    SciTech Connect

    Bengua, Gerard; Ishikawa, Masayori; Sutherland, Kenneth; Horita, Kenji; Yamazaki, Rie; Fujita, Katsuhisa; Onimaru, Rikiya; Katoh, Noriwo; Inoue, Tetsuya; Onodera, Shunsuke; Shirato, Hiroki

    2010-06-01

    Purpose: To evaluate the effectiveness of the stereotactic body frame (SBF), with or without a diaphragm press or a breathing cycle monitoring device (Abches), in controlling the range of lung tumor motion, by tracking the real-time position of fiducial markers. Methods and Materials: The trajectories of gold markers in the lung were tracked with the real-time tumor-tracking radiotherapy system. The SBF was used for patient immobilization and the diaphragm press and Abches were used to actively control breathing and for self-controlled respiration, respectively. Tracking was performed in five setups, with and without immobilization and respiration control. The results were evaluated using the effective range, which was defined as the range that includes 95% of all the recorded marker positions in each setup. Results: The SBF, with or without a diaphragm press or Abches, did not yield effective ranges of marker motion which were significantly different from setups that did not use these materials. The differences in the effective marker ranges in the upper lobes for all the patient setups were less than 1mm. Larger effective ranges were obtained for the markers in the middle or lower lobes. Conclusion: The effectiveness of controlling respiratory-induced organ motion by using the SBF+diaphragm press or SBF + Abches patient setups were highly dependent on the individual patient reaction to the use of these materials and the location of the markers. They may be considered for lung tumors in the lower lobes, but are not necessary for tumors in the upper lobes.

  12. Two-dimensional time-dependent vortex regions based on the acceleration magnitude.

    PubMed

    Kasten, Jens; Reininghaus, Jan; Hotz, Ingrid; Hege, Hans-Christian

    2011-12-01

    Acceleration is a fundamental quantity of flow fields that captures Galilean invariant properties of particle motion. Considering the magnitude of this field, minima represent characteristic structures of the flow that can be classified as saddle- or vortex-like. We made the interesting observation that vortex-like minima are enclosed by particularly pronounced ridges. This makes it possible to define boundaries of vortex regions in a parameter-free way. Utilizing scalar field topology, a robust algorithm can be designed to extract such boundaries. They can be arbitrarily shaped. An efficient tracking algorithm allows us to display the temporal evolution of vortices. Various vortex models are used to evaluate the method. We apply our method to two-dimensional model systems from computational fluid dynamics and compare the results to those arising from existing definitions.

  13. Plasma physics in noninertial frames

    SciTech Connect

    Thyagaraja, A.; McClements, K. G.

    2009-09-15

    Equations describing the nonrelativistic motion of a charged particle in an arbitrary noninertial reference frame are derived from the relativistically invariant form of the particle action. It is shown that the equations of motion can be written in the same form in inertial and noninertial frames, with the effective electric and magnetic fields in the latter modified by inertial effects associated with centrifugal and Coriolis accelerations. These modifications depend on the particle charge-to-mass ratio, and also the vorticity, specific kinetic energy, and compressibility of the frame flow. The Newton-Lorentz, Vlasov, and Fokker-Planck equations in such a frame are derived. Reduced models such as gyrokinetic, drift-kinetic, and fluid equations are then derivable from these equations in the appropriate limits, using standard averaging procedures. The results are applied to tokamak plasmas rotating about the machine symmetry axis with a nonrelativistic but otherwise arbitrary toroidal flow velocity. Astrophysical applications of the analysis are also possible since the power of the action principle is such that it can be used to describe relativistic flows in curved spacetime.

  14. Rank-based inference for the accelerated failure time model in the presence of interval censored data

    NASA Astrophysics Data System (ADS)

    Karimi, Mostafa; Ibrahim, Noor Akma; Bakar, Mohd. Rizam Abu; Arasan, Jayanthi

    2016-06-01

    Semiparametric analysis and rank-based inference for the accelerated failure time model are complicated in the presence of interval censored data. The main difficulty with the existing rank-based methods is that they involve estimating functions with the possibility of multiple roots. In this paper a class of asymptotically normal rank estimators is developed which can be aquired via linear programming for estimating the parameters of the model, and a two-step iterative algorithm is introduce for solving the estimating equations. The proposed inference procedures are assessed through a real example.

  15. Design and Evaluation of a Clock Multiplexing Circuit for the SSRL Booster Accelerator Timing System - Oral Presentation

    SciTech Connect

    Araya, Million

    2015-08-25

    SPEAR3 is a 234 m circular storage ring at SLAC’s synchrotron radiation facility (SSRL) in which a 3 GeV electron beam is stored for user access. Typically the electron beam decays with a time constant of approximately 10hr due to electron lose. In order to replenish the lost electrons, a booster synchrotron is used to accelerate fresh electrons up to 3GeV for injection into SPEAR3. In order to maintain a constant electron beam current of 500mA, the injection process occurs at 5 minute intervals. At these times the booster synchrotron accelerates electrons for injection at a 10Hz rate. A 10Hz 'injection ready' clock pulse train is generated when the booster synchrotron is operating. Between injection intervalswhere the booster is not running and hence the 10 Hz ‘injection ready’ signal is not present-a 10Hz clock is derived from the power line supplied by Pacific Gas and Electric (PG&E) to keep track of the injection timing. For this project I constructed a multiplexing circuit to 'switch' between the booster synchrotron 'injection ready' clock signal and PG&E based clock signal. The circuit uses digital IC components and is capable of making glitch-free transitions between the two clocks. This report details construction of a prototype multiplexing circuit including test results and suggests improvement opportunities for the final design.

  16. Complete cosmic scenario from inflation to late time acceleration: Nonequilibrium thermodynamics in the context of particle creation

    NASA Astrophysics Data System (ADS)

    Chakraborty, Subenoy; Saha, Subhajit

    2014-12-01

    The paper deals with the mechanism of particle creation in the framework of irreversible thermodynamics. The second order nonequilibrium thermodynamical prescription of Israel and Stewart has been presented with particle creation rate, treated as the dissipative effect. In the background of a flat Friedmann-Robertson-Walker (FRW) model, we assume the nonequilibrium thermodynamical process to be isentropic so that the entropy per particle does not change and consequently the dissipative pressure can be expressed linearly in terms of the particle creation rate. Here the dissipative pressure behaves as a dynamical variable having a nonlinear inhomogeneous evolution equation and the entropy flow vector satisfies the second law of thermodynamics. Further, using the Friedmann equations and by proper choice of the particle creation rate as a function of the Hubble parameter, it is possible to show (separately) a transition from the inflationary phase to the radiation era and also from the matter dominated era to late time acceleration. Also, in analogy to analytic continuation, it is possible to show a continuous cosmic evolution from inflation to late time acceleration by adjusting the parameters. It is found that in the de Sitter phase, the comoving entropy increases exponentially with time, keeping entropy per particle unchanged. Subsequently, the above cosmological scenarios have been described from a field theoretic point of view by introducing a scalar field having self-interacting potential. Finally, we make an attempt to show the cosmological phenomenon of particle creation as Hawking radiation, particularly during the inflationary era.

  17. Design and Evaluation of a Clock Multiplexing Circuit for the SSRL Booster Accelerator Timing System - Final Paper

    SciTech Connect

    Araya, Million

    2015-08-21

    SPEAR3 is a 234 m circular storage ring at SLAC’s synchrotron radiation facility (SSRL) in which a 3 GeV electron beam is stored for user access. Typically the electron beam decays with a time constant of approximately 10hr due to electron lose. In order to replenish the lost electrons, a booster synchrotron is used to accelerate fresh electrons up to 3GeV for injection into SPEAR3. In order to maintain a constant electron beam current of 500mA, the injection process occurs at 5 minute intervals. At these times the booster synchrotron accelerates electrons for injection at a 10Hz rate. A 10Hz 'injection ready' clock pulse train is generated when the booster synchrotron is operating. Between injection intervals-where the booster is not running and hence the 10 Hz ‘injection ready’ signal is not present-a 10Hz clock is derived from the power line supplied by Pacific Gas and Electric (PG&E) to keep track of the injection timing. For this project I constructed a multiplexing circuit to 'switch' between the booster synchrotron 'injection ready' clock signal and PG&E based clock signal. The circuit uses digital IC components and is capable of making glitch-free transitions between the two clocks. This report details construction of a prototype multiplexing circuit including test results and suggests improvement opportunities for the final design.

  18. SU-E-I-37: Low-Dose Real-Time Region-Of-Interest X-Ray Fluoroscopic Imaging with a GPU-Accelerated Spatially Different Bilateral Filtering

    SciTech Connect

    Chung, H; Lee, J; Pua, R; Cho, S; Jung, W

    2014-06-01

    Purpose: The purpose of our study is to reduce imaging radiation dose while maintaining image quality of region of interest (ROI) in X-ray fluoroscopy. A low-dose real-time ROI fluoroscopic imaging technique which includes graphics-processing-unit- (GPU-) accelerated image processing for brightness compensation and noise filtering was developed in this study. Methods: In our ROI fluoroscopic imaging, a copper filter is placed in front of the X-ray tube. The filter contains a round aperture to reduce radiation dose to outside of the aperture. To equalize the brightness difference between inner and outer ROI regions, brightness compensation was performed by use of a simple weighting method that applies selectively to the inner ROI, the outer ROI, and the boundary zone. A bilateral filtering was applied to the images to reduce relatively high noise in the outer ROI images. To speed up the calculation of our technique for real-time application, the GPU-acceleration was applied to the image processing algorithm. We performed a dosimetric measurement using an ion-chamber dosimeter to evaluate the amount of radiation dose reduction. The reduction of calculation time compared to a CPU-only computation was also measured, and the assessment of image quality in terms of image noise and spatial resolution was conducted. Results: More than 80% of dose was reduced by use of the ROI filter. The reduction rate depended on the thickness of the filter and the size of ROI aperture. The image noise outside the ROI was remarkably reduced by the bilateral filtering technique. The computation time for processing each frame image was reduced from 3.43 seconds with single CPU to 9.85 milliseconds with GPU-acceleration. Conclusion: The proposed technique for X-ray fluoroscopy can substantially reduce imaging radiation dose to the patient while maintaining image quality particularly in the ROI region in real-time.

  19. A Comparison of Reading Achievement in Second Grade Students Using the Accelerated Reading Program and Independent Reading.

    ERIC Educational Resources Information Center

    Toro, Adrienne

    Accelerated Reader is a computer program designed by Advantage Learning Systems to assess students' reading comprehension levels and keep detailed and accurate reports of such findings. This research studied the Accelerated Reader program with a second grade class over a 6-week time frame. One class of 20 students read books picked from the…

  20. Time-dependent Acceleration of Pickup Ions at The Heliospheric Termination Shock

    SciTech Connect

    Le Roux, J. A.

    2008-08-25

    It is discussed how a time-dependent focused transport model, using a time series of shock obliquities at the termination shock based on Voyager 1 observations to model magnetic field-line random walk, can reproduce observational features of energetic ions at the termination shock and in the heliosheath which is beyond the scope of standard cosmic-ray transport models.

  1. THE MATRYOSHKA RUN. II. TIME-DEPENDENT TURBULENCE STATISTICS, STOCHASTIC PARTICLE ACCELERATION, AND MICROPHYSICS IMPACT IN A MASSIVE GALAXY CLUSTER

    SciTech Connect

    Miniati, Francesco

    2015-02-10

    We use the Matryoshka run to study the time-dependent statistics of structure-formation-driven turbulence in the intracluster medium of a 10{sup 15} M {sub ☉} galaxy cluster. We investigate the turbulent cascade in the inner megaparsec for both compressional and incompressible velocity components. The flow maintains approximate conditions of fully developed turbulence, with departures thereof settling in about an eddy-turnover time. Turbulent velocity dispersion remains above 700 km s{sup –1} even at low mass accretion rate, with the fraction of compressional energy between 10% and 40%. The normalization and the slope of the compressional turbulence are susceptible to large variations on short timescales, unlike the incompressible counterpart. A major merger occurs around redshift z ≅ 0 and is accompanied by a long period of enhanced turbulence, ascribed to temporal clustering of mass accretion related to spatial clustering of matter. We test models of stochastic acceleration by compressional modes for the origin of diffuse radio emission in galaxy clusters. The turbulence simulation model constrains an important unknown of this complex problem and brings forth its dependence on the elusive microphysics of the intracluster plasma. In particular, the specifics of the plasma collisionality and the dissipation physics of weak shocks affect the cascade of compressional modes with strong impact on the acceleration rates. In this context radio halos emerge as complex phenomena in which a hierarchy of processes acting on progressively smaller scales are at work. Stochastic acceleration by compressional modes implies statistical correlation of radio power and spectral index with merging cores distance, both testable in principle with radio surveys.

  2. Hard X-ray time profiles and acceleration processes in large solar flares

    NASA Technical Reports Server (NTRS)

    Bai, T.; Ramaty, R.

    1979-01-01

    The hard X-ray time profiles of the (1972) August 4 and 7 flares are investigated, taking into account a comparison of the time profiles of different energy channels. It is shown that for these flares the temporal features of the intensity profiles of higher energy channels are delayed with respect to those of channel 1. The delay time gradually increases to approximately 5 sec as the channel number increases from 1 to 5, and it jumps to approximately 15 sec for channels 6 and 7. A description is presented of a model in which the delay and other characteristics of the observed time profiles in channels 1-5 are self-consistently explained by the increase of the electron energy loss time with electron energy.

  3. A drug-induced accelerated senescence (DIAS) is a possibility to study aging in time lapse.

    PubMed

    Alili, Lirija; Diekmann, Johanna; Giesen, Melanie; Holtkötter, Olaf; Brenneisen, Peter

    2014-06-01

    Currently, the oxidative stress (or free radical) theory of aging is the most popular explanation of how aging occurs at the molecular level. Accordingly, a stress-induced senescence-like phenotype of human dermal fibroblasts can be induced in vitro by the exposure of human diploid fibroblasts to subcytotoxic concentrations of hydrogen peroxide. However, several biomarkers of replicative senescence e.g. cell cycle arrest and enlarged morphology are abrogated 14 days after treatment, indicating that reactive oxygen species (ROS) rather acts as a trigger for short-term senescence (1-3 days) than being responsible for the maintenance of the senescence-like phenotype. Further, DNA-damaging factors are discussed resulting in a permanent senescent cell type. To induce long-term premature senescence and to understand the molecular alterations occurring during the aging process, we analyzed mitomycin C (MMC) as an alkylating DNA-damaging agent and ROS producer. Human dermal fibroblasts (HDF), used as model for skin aging, were exposed to non-cytotoxic concentrations of MMC and analyzed for potential markers of cellular aging, for example enlarged morphology, activity of senescence-associated-ß-galactosidase, cell cycle arrest, increased ROS production and MMP1-activity, which are well-documented for HDF in replicative senescence. Our data show that mitomycin C treatment results in a drug-induced accelerated senescence (DIAS) with long-term expression of senescence markers, demonstrating that a combination of different susceptibility factors, here ROS and DNA alkylation, are necessary to induce a permanent senescent cell type.

  4. Full time-resolved diffuse fluorescence tomography accelerated with parallelized Fourier-series truncated diffusion approximation.

    PubMed

    Yi, Xi; Wang, Bingyuan; Wan, Wenbo; Wang, Yihan; Zhang, Yanqi; Zhao, Huijuan; Gao, Feng

    2015-05-01

    Of the three measurement schemes established for diffuse fluorescence tomography (DFT), the time-domain scheme is well known to provide the richest information about the distribution of the targeting fluorophore in living tissues. However, the explicit use of the full time-resolved data usually leads to a considerably lengthy time for image reconstruction, limiting its applications to three-dimensional or small-volume imaging. To cope with the adversity, we propose herein a computationally efficient scheme for DFT image reconstruction where the time-dependent photon density is expanded to a Fourier-series and calculated by solving the independent frequency-domain diffusion equations at multiple sampling frequencies with the support of a combined multicore CPU-based coarse-grain and multithread GPU-based fine-grain parallelization strategy. With such a parallelized Fourier-series truncated diffusion approximation, both the time- and frequency-domain inversion procedures are developed and validated for their effectiveness and accuracy using simulative and phantom experiments. The results show that the proposed method can generate reconstructions comparable to the explicit time-domain scheme, with significantly reduced computational time.

  5. VIRTUAL FRAME BUFFER INTERFACE

    NASA Technical Reports Server (NTRS)

    Wolfe, T. L.

    1994-01-01

    Large image processing systems use multiple frame buffers with differing architectures and vendor supplied user interfaces. This variety of architectures and interfaces creates software development, maintenance, and portability problems for application programs. The Virtual Frame Buffer Interface program makes all frame buffers appear as a generic frame buffer with a specified set of characteristics, allowing programmers to write code which will run unmodified on all supported hardware. The Virtual Frame Buffer Interface converts generic commands to actual device commands. The virtual frame buffer consists of a definition of capabilities and FORTRAN subroutines that are called by application programs. The virtual frame buffer routines may be treated as subroutines, logical functions, or integer functions by the application program. Routines are included that allocate and manage hardware resources such as frame buffers, monitors, video switches, trackballs, tablets and joysticks; access image memory planes; and perform alphanumeric font or text generation. The subroutines for the various "real" frame buffers are in separate VAX/VMS shared libraries allowing modification, correction or enhancement of the virtual interface without affecting application programs. The Virtual Frame Buffer Interface program was developed in FORTRAN 77 for a DEC VAX 11/780 or a DEC VAX 11/750 under VMS 4.X. It supports ADAGE IK3000, DEANZA IP8500, Low Resolution RAMTEK 9460, and High Resolution RAMTEK 9460 Frame Buffers. It has a central memory requirement of approximately 150K. This program was developed in 1985.

  6. Quantum decoherence in noninertial frames

    SciTech Connect

    Wang Jieci; Jing Jiliang

    2010-09-15

    Quantum decoherence, which appears when a system interacts with its environment in an irreversible way, plays a fundamental role in the description of quantum-to-classical transitions and has been successfully applied in some important experiments. Here, we study the decoherence in noninertial frames. It is shown that the decoherence and loss of the entanglement generated by the Unruh effect will influence each other remarkably. It is interesting to note that, in the case of the total system under decoherence, the sudden death of entanglement may appear for any acceleration. However, in the case of only Rob's qubit undergoing decoherence, sudden death may only occur when the acceleration parameter is greater than a 'critical point'.

  7. Note: Real-time monitoring via second-harmonic interferometry of a flow gas cell for laser wakefield acceleration.

    PubMed

    Brandi, F; Giammanco, F; Conti, F; Sylla, F; Lambert, G; Gizzi, L A

    2016-08-01

    The use of a gas cell as a target for laser wakefield acceleration (LWFA) offers the possibility to obtain stable and manageable laser-plasma interaction process, a mandatory condition for practical applications of this emerging technique, especially in multi-stage accelerators. In order to obtain full control of the gas particle number density in the interaction region, thus allowing for a long term stable and manageable LWFA, real-time monitoring is necessary. In fact, the ideal gas law cannot be used to estimate the particle density inside the flow cell based on the preset backing pressure and the room temperature because the gas flow depends on several factors like tubing, regulators, and valves in the gas supply system, as well as vacuum chamber volume and vacuum pump speed/throughput. Here, second-harmonic interferometry is applied to measure the particle number density inside a flow gas cell designed for LWFA. The results demonstrate that real-time monitoring is achieved and that using low backing pressure gas (<1 bar) and different cell orifice diameters (<2 mm) it is possible to finely tune the number density up to the 10(19) cm(-3) range well suited for LWFA. PMID:27587174

  8. Note: Real-time monitoring via second-harmonic interferometry of a flow gas cell for laser wakefield acceleration.

    PubMed

    Brandi, F; Giammanco, F; Conti, F; Sylla, F; Lambert, G; Gizzi, L A

    2016-08-01

    The use of a gas cell as a target for laser wakefield acceleration (LWFA) offers the possibility to obtain stable and manageable laser-plasma interaction process, a mandatory condition for practical applications of this emerging technique, especially in multi-stage accelerators. In order to obtain full control of the gas particle number density in the interaction region, thus allowing for a long term stable and manageable LWFA, real-time monitoring is necessary. In fact, the ideal gas law cannot be used to estimate the particle density inside the flow cell based on the preset backing pressure and the room temperature because the gas flow depends on several factors like tubing, regulators, and valves in the gas supply system, as well as vacuum chamber volume and vacuum pump speed/throughput. Here, second-harmonic interferometry is applied to measure the particle number density inside a flow gas cell designed for LWFA. The results demonstrate that real-time monitoring is achieved and that using low backing pressure gas (<1 bar) and different cell orifice diameters (<2 mm) it is possible to finely tune the number density up to the 10(19) cm(-3) range well suited for LWFA.

  9. Note: Real-time monitoring via second-harmonic interferometry of a flow gas cell for laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Brandi, F.; Giammanco, F.; Conti, F.; Sylla, F.; Lambert, G.; Gizzi, L. A.

    2016-08-01

    The use of a gas cell as a target for laser wakefield acceleration (LWFA) offers the possibility to obtain stable and manageable laser-plasma interaction process, a mandatory condition for practical applications of this emerging technique, especially in multi-stage accelerators. In order to obtain full control of the gas particle number density in the interaction region, thus allowing for a long term stable and manageable LWFA, real-time monitoring is necessary. In fact, the ideal gas law cannot be used to estimate the particle density inside the flow cell based on the preset backing pressure and the room temperature because the gas flow depends on several factors like tubing, regulators, and valves in the gas supply system, as well as vacuum chamber volume and vacuum pump speed/throughput. Here, second-harmonic interferometry is applied to measure the particle number density inside a flow gas cell designed for LWFA. The results demonstrate that real-time monitoring is achieved and that using low backing pressure gas (<1 bar) and different cell orifice diameters (<2 mm) it is possible to finely tune the number density up to the 1019 cm-3 range well suited for LWFA.

  10. Graphics processing unit-accelerated real-time compressive sensing spectral domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Xu, Daguang; Huang, Yong; Kang, Jin U.

    2015-03-01

    In this paper, we systematically demonstrate two real-time CS SD OCT systems based on a conventional desktop having three GPUs. The first one takes fast Fourier transform (FFT) as the sensing technique and under-sampled linear wavenumber spectral sampling as input data, while the second one uses non-uniform fast Fourier transform (NUFFT) and under-sampled nonlinear wavenumber spectral sampling, respectively. The maximum reconstruction speed of 72k and 33.5k A-line/s were achieved for these two systems, respectively, with A-scan size 2048. It is >100 times faster than the C++ implementation and >400 times faster than the MATLAB implementation. Finally, we present real-time dispersion compensated image reconstruction for both systems.

  11. Towards the theory of regular accelerating Universe in Riemann-Cartan space-time

    NASA Astrophysics Data System (ADS)

    Minkevich, A. V.

    2016-01-01

    The problems of modern cosmology and attempts of its solution are considered. The applying of gravitation theory in the Riemann-Cartan space-time as the most natural generalization of Einstein gravitation theory in order to solve the principal cosmological problems is discussed. The gravitation theory in the Riemann-Cartan space-time leading to the solution of the problem of cosmological singularity and dark energy problem is analyzed.

  12. Graphic processing unit accelerated real-time partially coherent beam generator

    NASA Astrophysics Data System (ADS)

    Ni, Xiaolong; Liu, Zhi; Chen, Chunyi; Jiang, Huilin; Fang, Hanhan; Song, Lujun; Zhang, Su

    2016-07-01

    A method of using liquid-crystals (LCs) to generate a partially coherent beam in real-time is described. An expression for generating a partially coherent beam is given and calculated using a graphic processing unit (GPU), i.e., the GeForce GTX 680. A liquid-crystal on silicon (LCOS) with 256 × 256 pixels is used as the partially coherent beam generator (PCBG). An optimizing method with partition convolution is used to improve the generating speed of our LC PCBG. The total time needed to generate a random phase map with a coherence width range from 0.015 mm to 1.5 mm is less than 2.4 ms for calculation and readout with the GPU; adding the time needed for the CPU to read and send to LCOS with the response time of the LC PCBG, the real-time partially coherent beam (PCB) generation frequency of our LC PCBG is up to 312 Hz. To our knowledge, it is the first real-time partially coherent beam generator. A series of experiments based on double pinhole interference are performed. The result shows that to generate a laser beam with a coherence width of 0.9 mm and 1.5 mm, with a mean error of approximately 1%, the RMS values needed 0.021306 and 0.020883 and the PV values required 0.073576 and 0.072998, respectively.

  13. Unifying phantom inflation with late-time acceleration: scalar phantom-non-phantom transition model and generalized holographic dark energy

    NASA Astrophysics Data System (ADS)

    Nojiri, Shin'ichi; Odintsov, Sergei D.

    2006-08-01

    The unifying approach to early-time and late-time universe based on phantom cosmology is proposed. We consider gravity-scalar system which contains usual potential and scalar coupling function in front of kinetic term. As a result, the possibility of phantom-non-phantom transition appears in such a way that universe could have effectively phantom equation of state at early time as well as at late time. In fact, the oscillating universe may have several phantom and non-phantom phases. Role in each of two phase and can be absorbed into the redefinition of the scalar field. Right on the transition point, however, the factor cannot be absorbed into the redefinition and play the role to connect two phases smoothly. Holographic dark energy where infrared cutoff is identified with combination of FRW parameters: Hubble constant, particle and future horizons, cosmological constant and universe life-time (if finite). Depending on the specific choice of the model the number of interesting effects occur: the possibility to solve the coincidence problem, crossing of phantom divide and unification of early-time inflationary and late-time accelerating phantom universe. The bound for holographic entropy which decreases in phantom era is also discussed.

  14. Applicability of time-to-failure analysis to accelerated strain before earthquakes and volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Main, Ian G.

    1999-12-01

    We examine quantitatively the ranges of applicability of the equation Ω=A+B[1-t/tf]m for predicting `system-sized' failure times tf in the Earth. In applications Ω is a proxy measure for strain or crack length, and A, B and the index m are model parameters determined by curve fitting. We consider constitutive rules derived from (a) Charles' law for subcritical crack growth; (b) Voight's equation; and (c) a simple percolation model, and show in each case that this equation holds only when m<0. When m>0, the general solution takes the form Ω=A+B[1+t/T]m, where T is a positive time constant, and no failure time can be defined. Reported values for volcanic precursors based on rate data are found to be within the range of applicability of time-to-failure analysis (m<0). The same applies to seismic moment release before earthquakes, at the expense of poor retrospective predictability of the time of the a posteriori-defined main shock. In contrast, reported values based on increasing cumulative Benioff strain occur in the region where a system-sized failure time cannot be defined (m>0 commonly m~0.3). We conclude on physical grounds that cumulative seismic moment is preferred as the most direct measure of seismic strain. If cumulative Benioff strain is to be retained on empirical grounds, then it is important that these data either be re-examined with the independent constraint m<0, or that for the case 0time-integration of cumulative data be applied, of the form ΣΩ=At+B'{1-[1-t/tf]m+1}.

  15. Magnetospheric Multiscale Satellite Observations of Parallel Electron Acceleration in Magnetic Field Reconnection by Fermi Reflection from Time Domain Structures.

    PubMed

    Mozer, F S; Agapitov, O A; Artemyev, A; Burch, J L; Ergun, R E; Giles, B L; Mourenas, D; Torbert, R B; Phan, T D; Vasko, I

    2016-04-01

    The same time domain structures (TDS) have been observed on two Magnetospheric Multiscale Satellites near Earth's dayside magnetopause. These TDS, traveling away from the X line along the magnetic field at 4000  km/s, accelerated field-aligned ∼5  eV electrons to ∼200  eV by a single Fermi reflection of the electrons by these overtaking barriers. Additionally, the TDS contained both positive and negative potentials, so they were a mixture of electron holes and double layers. They evolve in ∼10  km of space or 7 ms of time and their spatial scale size is 10-20 km, which is much larger than the electron gyroradius (<1  km) or the electron inertial length (4 km at the observation point, less nearer the X line). PMID:27104714

  16. Bone Mineral Content and Density Among Female NCAA Division I Athletes Across the Competitive Season and Over a Multi-Year Time Frame.

    PubMed

    Stanforth, Dixie; Lu, Tao; Stults-Kolehmainen, Matthew A; Crim, Brittany N; Stanforth, Philip R

    2016-10-01

    Stanforth, D, Lu, T, Stults-Kolehmainen, MA, Crim, BN, and Stanforth, PR. Bone mineral content and density among female NCAA Division I athletes across the competitive season and over a multi-year time frame. J Strength Cond Res 30(10): 2828-2838, 2016-Longitudinal and cross-sectional bone mineral content (BMC) and bone mineral density (BMD) comparisons were made among impact and nonimpact sports. Female collegiate athletes, 18-23 years of age, from basketball (BB; n = 38), soccer (SOC; n = 47), swimming (SW; n = 52), track sprinters and jumpers (TR; n = 49), and volleyball (VB; n = 26) had BMC/BMD measures preseason and postseason over 3 years. Control groups of 85 college females, 18-24 years of age, who completed 2 tests 1-3 years apart and of 170 college females, 18-20 years of age, were used for the longitudinal and cross-sectional analyses, respectively. A restricted maximum likelihood linear mixed model regression analysis with a compound symmetric heterogeneous variance-covariance matrix structure was used for all analyses (p ≤ 0.05). Increases from year-1 preseason to year-3 postseason included the following: total BMC (3.3%), total BMD (1.4%), and spine BMD (4.5%) for BB; total BMC (1.5%) and leg BMD (1.2%) for SOC; arm (1.8%), leg (1.9%), and total BMD (5.7%) for SW; total BMC (2.0%), arm (1.7%), leg (2.3%), pelvis (3.4%), spine (6.0%), and total BMD (2.3%) for TR; and arm (4.1%), leg (2.0%), pelvis (2.0%), spine (2.0%), and total BMD (2.7%) for VB. Comparisons among sports determined that BB had higher BMC and BMD values than all other sports for all variables except spine and total BMD; BB, SOC, TR, and VB had higher total BMC (11-29%), leg BMD (13-20%), and total BMD (9-15%) than SW and CON, and there were few differences among SOC, TR, and VB. In conclusion, small, significant increases in many BMC and BMD measures occur during female athlete's collegiate careers. The BMC and BMD differences between impact and nonimpact sports are large compared

  17. The time dependent propensity function for acceleration of spatial stochastic simulation of reaction-diffusion systems

    NASA Astrophysics Data System (ADS)

    Fu, Jin; Wu, Sheng; Li, Hong; Petzold, Linda R.

    2014-10-01

    The inhomogeneous stochastic simulation algorithm (ISSA) is a fundamental method for spatial stochastic simulation. However, when diffusion events occur more frequently than reaction events, simulating the diffusion events by ISSA is quite costly. To reduce this cost, we propose to use the time dependent propensity function in each step. In this way we can avoid simulating individual diffusion events, and use the time interval between two adjacent reaction events as the simulation stepsize. We demonstrate that the new algorithm can achieve orders of magnitude efficiency gains over widely-used exact algorithms, scales well with increasing grid resolution, and maintains a high level of accuracy.

  18. The Time Dependent Propensity Function for Acceleration of Spatial Stochastic Simulation of Reaction-Diffusion Systems

    PubMed Central

    Wu, Sheng; Li, Hong; Petzold, Linda R.

    2015-01-01

    The inhomogeneous stochastic simulation algorithm (ISSA) is a fundamental method for spatial stochastic simulation. However, when diffusion events occur more frequently than reaction events, simulating the diffusion events by ISSA is quite costly. To reduce this cost, we propose to use the time dependent propensity function in each step. In this way we can avoid simulating individual diffusion events, and use the time interval between two adjacent reaction events as the simulation stepsize. We demonstrate that the new algorithm can achieve orders of magnitude efficiency gains over widely-used exact algorithms, scales well with increasing grid resolution, and maintains a high level of accuracy. PMID:26609185

  19. The time dependent propensity function for acceleration of spatial stochastic simulation of reaction–diffusion systems

    SciTech Connect

    Fu, Jin; Wu, Sheng; Li, Hong; Petzold, Linda R.

    2014-10-01

    The inhomogeneous stochastic simulation algorithm (ISSA) is a fundamental method for spatial stochastic simulation. However, when diffusion events occur more frequently than reaction events, simulating the diffusion events by ISSA is quite costly. To reduce this cost, we propose to use the time dependent propensity function in each step. In this way we can avoid simulating individual diffusion events, and use the time interval between two adjacent reaction events as the simulation stepsize. We demonstrate that the new algorithm can achieve orders of magnitude efficiency gains over widely-used exact algorithms, scales well with increasing grid resolution, and maintains a high level of accuracy.

  20. PROBING DYNAMICS OF ELECTRON ACCELERATION WITH RADIO AND X-RAY SPECTROSCOPY, IMAGING, AND TIMING IN THE 2002 APRIL 11 SOLAR FLARE

    SciTech Connect

    Fleishman, Gregory D.; Nita, Gelu M.; Gary, Dale E.; Kontar, Eduard P.

    2013-05-10

    Based on detailed analysis of radio and X-ray observations of a flare on 2002 April 11 augmented by realistic three-dimensional modeling, we have identified a radio emission component produced directly at the flare acceleration region. This acceleration region radio component has distinctly different (1) spectrum, (2) light curves, (3) spatial location, and, thus, (4) physical parameters from those of the separately identified trapped or precipitating electron components. To derive evolution of physical parameters of the radio sources we apply forward fitting of the radio spectrum time sequence with the gyrosynchrotron source function with five to six free parameters. At the stage when the contribution from the acceleration region dominates the radio spectrum, the X-ray- and radio-derived electron energy spectral indices agree well with each other. During this time the maximum energy of the accelerated electron spectrum displays a monotonic increase with time from {approx}300 keV to {approx}2 MeV over roughly one minute duration indicative of an acceleration process in the form of growth of the power-law tail; the fast electron residence time in the acceleration region is about 2-4 s, which is much longer than the time of flight and so requires a strong diffusion mode there to inhibit free-streaming propagation. The acceleration region has a relatively strong magnetic field, B {approx} 120 G, and a low thermal density, n{sub e} {approx}< 2 Multiplication-Sign 10{sup 9} cm{sup -3}. These acceleration region properties are consistent with a stochastic acceleration mechanism.

  1. GPU-accelerated Modeling and Element-free Reverse-time Migration with Gauss Points Partition

    NASA Astrophysics Data System (ADS)

    Zhen, Z.; Jia, X.

    2014-12-01

    Element-free method (EFM) has been applied to seismic modeling and migration. Compared with finite element method (FEM) and finite difference method (FDM), it is much cheaper and more flexible because only the information of the nodes and the boundary of the study area are required in computation. In the EFM, the number of Gauss points should be consistent with the number of model nodes; otherwise the accuracy of the intermediate coefficient matrices would be harmed. Thus when we increase the nodes of velocity model in order to obtain higher resolution, we find that the size of the computer's memory will be a bottleneck. The original EFM can deal with at most 81×81 nodes in the case of 2G memory, as tested by Jia and Hu (2006). In order to solve the problem of storage and computation efficiency, we propose a concept of Gauss points partition (GPP), and utilize the GPUs to improve the computation efficiency. Considering the characteristics of the Gaussian points, the GPP method doesn't influence the propagation of seismic wave in the velocity model. To overcome the time-consuming computation of the stiffness matrix (K) and the mass matrix (M), we also use the GPUs in our computation program. We employ the compressed sparse row (CSR) format to compress the intermediate sparse matrices and try to simplify the operations by solving the linear equations with the CULA Sparse's Conjugate Gradient (CG) solver instead of the linear sparse solver 'PARDISO'. It is observed that our strategy can significantly reduce the computational time of K and Mcompared with the algorithm based on CPU. The model tested is Marmousi model. The length of the model is 7425m and the depth is 2990m. We discretize the model with 595x298 nodes, 300x300 Gauss cells and 3x3 Gauss points in each cell. In contrast to the computational time of the conventional EFM, the GPUs-GPP approach can substantially improve the efficiency. The speedup ratio of time consumption of computing K, M is 120 and the

  2. CUDA Fortran acceleration for the finite-difference time-domain method

    NASA Astrophysics Data System (ADS)

    Hadi, Mohammed F.; Esmaeili, Seyed A.

    2013-05-01

    A detailed description of programming the three-dimensional finite-difference time-domain (FDTD) method to run on graphical processing units (GPUs) using CUDA Fortran is presented. Two FDTD-to-CUDA thread-block mapping designs are investigated and their performances compared. Comparative assessment of trade-offs between GPU's shared memory and L1 cache is also discussed. This presentation is for the benefit of FDTD programmers who work exclusively with Fortran and are reluctant to port their codes to C in order to utilize GPU computing. The derived CUDA Fortran code is compared with an optimized CPU version that runs on a workstation-class CPU to present a realistic GPU to CPU run time comparison and thus help in making better informed investment decisions on FDTD code redesigns and equipment upgrades. All analyses are mirrored with CUDA C simulations to put in perspective the present state of CUDA Fortran development.

  3. GPU-accelerated real-time IR smoke screen simulation and assessment of its obscuration

    NASA Astrophysics Data System (ADS)

    Wu, Xin; Zhang, Jian-qi; Huang, Xi; Liu, De-lian

    2012-01-01

    With the growing demand for the Battlefield Environment Simulation (BES), IR smoke screen, which is computationally expensive and absolutely indispensable, should be modeled true to life and correct in its thermal radiation characteristics. This paper analyzes the features of an IR smoke screen, and represents an IR smoke screen model based on light extinction, particle dispersion and temperature attenuation, which is calculated by GPU and rendered to screen in real time. Thus a method considering both the real-life in profile and the real-time in efficiency is presented. Additionally, the comparison between the simulated results and the measured data is made to verify the correctness of the smoke screen's obscuration, which illustrates the effect of its interference feature in an infrared scene.

  4. Accelerating Time-Varying Hardware Volume Rendering Using TSP Trees and Color-Based Error Metrics

    NASA Technical Reports Server (NTRS)

    Ellsworth, David; Chiang, Ling-Jen; Shen, Han-Wei; Kwak, Dochan (Technical Monitor)

    2000-01-01

    This paper describes a new hardware volume rendering algorithm for time-varying data. The algorithm uses the Time-Space Partitioning (TSP) tree data structure to identify regions within the data that have spatial or temporal coherence. By using this coherence, the rendering algorithm can improve performance when the volume data is larger than the texture memory capacity by decreasing the amount of textures required. This coherence can also allow improved speed by appropriately rendering flat-shaded polygons instead of textured polygons, and by not rendering transparent regions. To reduce the polygonization overhead caused by the use of the hierarchical data structure, we introduce an optimization method using polygon templates. The paper also introduces new color-based error metrics, which more accurately identify coherent regions compared to the earlier scalar-based metrics. By showing experimental results from runs using different data sets and error metrics, we demonstrate that the new methods give substantial improvements in volume rendering performance.

  5. Accelerating the Customer-Driven Microgrid Through Real-Time Digital Simulation

    SciTech Connect

    I. Leonard; T. Baldwin; M. Sloderbeck

    2009-07-01

    Comprehensive design and testing of realistic customer-driven microgrids requires a high performance simulation platform capable of incorporating power system and control models with external hardware systems. Traditional non real-time simulation is unable to fully capture the level of detail necessary to expose real-world implementation issues. With a real-time digital simulator as its foundation, a high-fidelity simulation environment that includes a robust electrical power system model, advanced control architecture, and a highly adaptable communication network is introduced. Hardware-in-the-loop implementation approaches for the hardware-based control and communication systems are included. An overview of the existing power system model and its suitability for investigation of autonomous island formation within the microgrid is additionally presented. Further test plans are also documented.

  6. Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

    NASA Technical Reports Server (NTRS)

    Kessel, R. L.; Armstrong, T. P.; Nuber, R.; Bandle, J.

    1985-01-01

    Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail.

  7. Real-time particle-detection probabilities in accelerated macroscopic detectors

    NASA Astrophysics Data System (ADS)

    Anastopoulos, Charis; Savvidou, Ntina

    2015-01-01

    We construct the detection rate for particle detectors moving along non-inertial trajectories and interacting with quantum fields. The detectors described here are characterized by the presence of records of observation throughout their history, so that the detection rate corresponds to directly measurable quantities. This is in contrast to past treatments of detectors, which actually refer to probes, i.e., microscopic systems from which we extract information only after their interaction has been completed. Our treatment incorporates the irreversibility due to the creation of macroscopic records of observation. The key result is a real-time description of particle detection and a rigorously defined time-local probability density function (PDF). The PDF depends on the scale of the temporal coarse-graining that is necessary for the formation of a macroscopic record. The evaluation of the PDF for Unruh-DeWitt detectors along different types of trajectory shows that only paths with at least one characteristic time-scale much smaller than lead to appreciable particle detection. Our approach allows for averaging over fast motions and thus predicts a constant detection rate for all fast periodic motions.

  8. Storm time impulsive enhancements of energetic oxygen due to adiabatic acceleration of preexisting warm oxygen in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Keika, Kunihiro; Seki, Kanako; Nosé, Masahito; Machida, Shinobu; Miyoshi, Yoshizumi; Lanzerotti, Louis J.; Mitchell, Donald G.; Gkioulidou, Matina; Turner, Drew; Spence, Harlan; Larsen, Brian A.

    2016-08-01

    We examine enhancements of energetic (>50 keV) oxygen ions observed by the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument on board the Van Allen Probes spacecraft in the inner magnetosphere (L ~ 6) at 22-23 h magnetic local time (MLT) during an injection event of the 6 June 2013 storm. Simultaneous observations by two Van Allen Probes spacecraft located close together (~0.5 RE) indicate that particle injections occurred in the premidnight sector (< ~24 h MLT). We also examine the evolution of the proton and oxygen energy spectra at L ~ 6 during the injection event. The spectral slope did not significantly change during the storm. The oxygen phase space density (PSD) was shifted toward higher PSD in a wide range of the first adiabatic invariant. The spectral evolution manifests the characteristics of adiabatic acceleration and density increase of oxygen ions. Warm (0.1-10 keV) oxygen measured by the Helium, Oxygen, Proton, and Electron (HOPE) instrument was enhanced prior to the storm mostly in magnetic field-aligned directions. The most reasonable scenario of this event is that warm oxygen ions that preexisted in the inner magnetosphere were picked up and adiabatically transported and accelerated by spatially localized, temporarily impulsive electric fields.

  9. Time dependent three-dimensional body frame quantal wave packet treatment of the H + H2 exchange reaction on the Liu-Siegbahn-Truhlar-Horowitz (LSTH) surface

    NASA Technical Reports Server (NTRS)

    Neuhauser, Daniel; Baer, Michael; Judson, Richard S.; Kouri, Donald J.

    1989-01-01

    The first successful application of the three-dimensional quantum body frame wave packet approach to reactive scattering is reported for the H + H2 exchange reaction on the LSTH potential surface. The method used is based on a procedure for calculating total reaction probabilities from wave packets. It is found that converged, vibrationally resolved reactive probabilities can be calculated with a grid that is not much larger than required for the pure inelastic calculation. Tabular results are presented for several energies.

  10. Frame independent cosmological perturbations

    SciTech Connect

    Prokopec, Tomislav; Weenink, Jan E-mail: j.g.weenink@uu.nl

    2013-09-01

    We compute the third order gauge invariant action for scalar-graviton interactions in the Jordan frame. We demonstrate that the gauge invariant action for scalar and tensor perturbations on one physical hypersurface only differs from that on another physical hypersurface via terms proportional to the equation of motion and boundary terms, such that the evolution of non-Gaussianity may be called unique. Moreover, we demonstrate that the gauge invariant curvature perturbation and graviton on uniform field hypersurfaces in the Jordan frame are equal to their counterparts in the Einstein frame. These frame independent perturbations are therefore particularly useful in relating results in different frames at the perturbative level. On the other hand, the field perturbation and graviton on uniform curvature hypersurfaces in the Jordan and Einstein frame are non-linearly related, as are their corresponding actions and n-point functions.

  11. Real-time atmospheric imaging and processing with hybrid adaptive optics and hardware accelerated lucky-region fusion (LRF) algorithm

    NASA Astrophysics Data System (ADS)

    Liu, Jony Jiang; Carhart, Gary W.; Beresnev, Leonid A.; Aubailly, Mathieu; Jackson, Christopher R.; Ejzak, Garrett; Kiamilev, Fouad E.

    2014-09-01

    Atmospheric turbulences can significantly deteriorate the performance of long-range conventional imaging systems and create difficulties for target identification and recognition. Our in-house developed adaptive optics (AO) system, which contains high-performance deformable mirrors (DMs) and the fast stochastic parallel gradient decent (SPGD) control mechanism, allows effective compensation of such turbulence-induced wavefront aberrations and result in significant improvement on the image quality. In addition, we developed advanced digital synthetic imaging and processing technique, "lucky-region" fusion (LRF), to mitigate the image degradation over large field-of-view (FOV). The LRF algorithm extracts sharp regions from each image obtained from a series of short exposure frames and fuses them into a final improved image. We further implemented such algorithm into a VIRTEX-7 field programmable gate array (FPGA) and achieved real-time video processing. Experiments were performed by combining both AO and hardware implemented LRF processing technique over a near-horizontal 2.3km atmospheric propagation path. Our approach can also generate a universal real-time imaging and processing system with a general camera link input, a user controller interface, and a DVI video output.

  12. Dynamic real-time 4D cardiac MDCT image display using GPU-accelerated volume rendering.

    PubMed

    Zhang, Qi; Eagleson, Roy; Peters, Terry M

    2009-09-01

    Intraoperative cardiac monitoring, accurate preoperative diagnosis, and surgical planning are important components of minimally-invasive cardiac therapy. Retrospective, electrocardiographically (ECG) gated, multidetector computed tomographical (MDCT), four-dimensional (3D + time), real-time, cardiac image visualization is an important tool for the surgeon in such procedure, particularly if the dynamic volumetric image can be registered to, and fused with the actual patient anatomy. The addition of stereoscopic imaging provides a more intuitive environment by adding binocular vision and depth cues to structures within the beating heart. In this paper, we describe the design and implementation of a comprehensive stereoscopic 4D cardiac image visualization and manipulation platform, based on the opacity density radiation model, which exploits the power of modern graphics processing units (GPUs) in the rendering pipeline. In addition, we present a new algorithm to synchronize the phases of the dynamic heart to clinical ECG signals, and to calculate and compensate for latencies in the visualization pipeline. A dynamic multiresolution display is implemented to enable the interactive selection and emphasis of volume of interest (VOI) within the entire contextual cardiac volume and to enhance performance, and a novel color and opacity adjustment algorithm is designed to increase the uniformity of the rendered multiresolution image of heart. Our system provides a visualization environment superior to noninteractive software-based implementations, but with a rendering speed that is comparable to traditional, but inferior quality, volume rendering approaches based on texture mapping. This retrospective ECG-gated dynamic cardiac display system can provide real-time feedback regarding the suspected pathology, function, and structural defects, as well as anatomical information such as chamber volume and morphology.

  13. Effect of bedrest and positive radial acceleration upon peripheral visual response time.

    NASA Technical Reports Server (NTRS)

    Haines, R. F.

    1972-01-01

    Attempt to determine if peripheral visual response time (RT) could be used as a reliable advanced predictor of +G sub z-related blackout or grayout. The relatively high luminance of the peripheral stimuli used in the experiments may account for the finding that peripheral RT was not sensitive to impending blackout or grayout. The relatively consistent mean RTs within subjects across test days in bed is probably due to the relatively constant response characteristics of the retina and to the high repeatability of the stimuli.

  14. Convergence acceleration for time-independent first-order PDE using optimal PNB-approximations

    SciTech Connect

    Holmgren, S.; Branden, H.

    1996-12-31

    We consider solving time-independent (steady-state) flow problems in 2D or 3D governed by hyperbolic or {open_quotes}almost hyperbolic{close_quotes} systems of partial differential equations (PDE). Examples of such PDE are the Euler and the Navier-Stokes equations. The PDE is discretized using a finite difference or finite volume scheme with arbitrary order of accuracy. If the matrix B describes the discretized differential operator and u denotes the approximate solution, the discrete problem is given by a large system of equations.

  15. A new perspective on global mean sea level (GMSL) acceleration

    NASA Astrophysics Data System (ADS)

    Watson, Phil J.

    2016-06-01

    The vast body of contemporary climate change science is largely underpinned by the premise of a measured acceleration from anthropogenic forcings evident in key climate change proxies -- greenhouse gas emissions, temperature, and mean sea level. By virtue, over recent years, the issue of whether or not there is a measurable acceleration in global mean sea level has resulted in fierce, widespread professional, social, and political debate. Attempts to measure acceleration in global mean sea level (GMSL) have often used comparatively crude analysis techniques providing little temporal instruction on these key questions. This work proposes improved techniques to measure real-time velocity and acceleration based on five GMSL reconstructions spanning the time frame from 1807 to 2014 with substantially improved temporal resolution. While this analysis highlights key differences between the respective reconstructions, there is now more robust, convincing evidence of recent acceleration in the trend of GMSL.

  16. Frame Rate and Human Vision

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.

    2012-01-01

    To enhance the quality of the theatre experience, the film industry is interested in achieving higher frame rates for capture and display. In this talk I will describe the basic spatio-temporal sensitivities of human vision, and how they respond to the time sequence of static images that is fundamental to cinematic presentation.

  17. Modified gravity à la Galileon: Late time cosmic acceleration and observational constraints

    NASA Astrophysics Data System (ADS)

    Ali, Amna; Gannouji, Radouane; Sami, M.

    2010-11-01

    In this paper we examine the cosmological consequences of fourth order Galileon gravity. We carry out detailed investigations of the underlying dynamics and demonstrate the stability of one de Sitter phase. The stable de Sitter phase contains a Galileon field π which is an increasing function of time (π˙>0). Using the required suppression of the fifth force, supernovae, Baryon acoustic oscillations, and CMB data, we constrain parameters of the model. We find that the π matter coupling parameter β is constrained to small numerical values such that β<0.02. We also show that the parameters of the third and fourth order in the action (c3,c4) are not independent and with reasonable assumptions, we obtain constraints on them. We investigate the growth history of the model and find that the subhorizon approximation is not allowed for this model. We demonstrate strong scale dependence of linear perturbations in the fourth order Galileon gravity.

  18. Denoising NMR time-domain signal by singular-value decomposition accelerated by graphics processing units.

    PubMed

    Man, Pascal P; Bonhomme, Christian; Babonneau, Florence

    2014-01-01

    We present a post-processing method that decreases the NMR spectrum noise without line shape distortion. As a result the signal-to-noise (S/N) ratio of a spectrum increases. This method is called Cadzow enhancement procedure that is based on the singular-value decomposition of time-domain signal. We also provide software whose execution duration is a few seconds for typical data when it is executed in modern graphic-processing unit. We tested this procedure not only on low sensitive nucleus (29)Si in hybrid materials but also on low gyromagnetic ratio, quadrupole nucleus (87)Sr in reference sample Sr(NO3)2. Improving the spectrum S/N ratio facilitates the determination of T/Q ratio of hybrid materials. It is also applicable to simulated spectrum, resulting shorter simulation duration for powder averaging. An estimation of the number of singular values needed for denoising is also provided. PMID:24880899

  19. Modified gravity a la Galileon: Late time cosmic acceleration and observational constraints

    SciTech Connect

    Ali, Amna; Sami, M.; Gannouji, Radouane

    2010-11-15

    In this paper we examine the cosmological consequences of fourth order Galileon gravity. We carry out detailed investigations of the underlying dynamics and demonstrate the stability of one de Sitter phase. The stable de Sitter phase contains a Galileon field {pi} which is an increasing function of time ({pi}>0). Using the required suppression of the fifth force, supernovae, Baryon acoustic oscillations, and CMB data, we constrain parameters of the model. We find that the {pi} matter coupling parameter {beta} is constrained to small numerical values such that {beta}<0.02. We also show that the parameters of the third and fourth order in the action (c{sub 3},c{sub 4}) are not independent and with reasonable assumptions, we obtain constraints on them. We investigate the growth history of the model and find that the subhorizon approximation is not allowed for this model. We demonstrate strong scale dependence of linear perturbations in the fourth order Galileon gravity.

  20. Unruh effect in a real scalar field with the Higgs potential on a dynamically variable background space-time

    NASA Astrophysics Data System (ADS)

    Takeuchi, Shingo

    2015-09-01

    It is predicted that an accelerating electron performs a Brownian motion in the inertial frame. This Brownian motion in the inertial frame has its roots in the interaction with the thermal excitation given by the Unruh effect in the accelerating frame. If such a prediction is possible, correspondingly we propose a prediction in this study that the thermal radiation is emitted in the inertial frame from an electron heated due to the Unruh effect in the accelerating frame. The point in our prediction is, although the Unruh effect is limited in the accelerating frame, as well as that the Brownian motion rooted in the Unruh effect appears in the inertial frame, the heat of the particle appears in the inertial frame. Based on such a prediction in this paper, we investigate phenomena in the neighborhood of an accelerating electron in the inertial frame. The model we consider is the four-dimensional Klein-Gordon real scalar field model with the Higgs potential term at the finite temperature identified with the Unruh temperature on the de Sitter space-time. We calculate the one-loop effective potential in the inertial frame with the corrections by the thermal radiation rooted in the Unruh effect in the accelerating frame. In this calculation, we take into account that the background space-time is deformed due to the field theory's corrected one-loop effective potential. Based on such an analysis, we illustrate the restoration of the spontaneous symmetry breaking and the dynamical variation of the background space-time, and we examine the accelerating particle's world-line and the amount of the energy corresponding to the change of the acceleration.

  1. Real-time thermal imaging of microwave accelerated metal-enhanced fluorescence (MAMEF) based assays on sapphire plates.

    PubMed

    Previte, Michael J R; Zhang, Yongxia; Aslan, Kadir; Geddes, Chris D

    2007-11-01

    In this paper, we describe an optical geometry that facilitates our further characterization of the temperature changes above silver island films (SiFs) on sapphire plates, when exposed to microwave radiation. Since sapphire transmits IR, we designed an optical scheme to capture real-time temperature images of a thin water film on sapphire plates with and without SiFs during the application of a short microwave pulse. Using this optical scheme, we can accurately determine the temperature profile of solvents in proximity to metal structures when exposed to microwave irradiation. We believe that this optical scheme will provide us with a basis for further studies in designing metal structures to further improve plasmonic-fluorescence clinical sensing applications, such as those used in microwave accelerated metal-enhanced fluorescence (MAMEF). PMID:17902038

  2. Increasing the multiscale/multiphysics capability of CAM-SE using implicit time integration and GPU accelerators

    NASA Astrophysics Data System (ADS)

    Archibald, R.; Evans, K. J.; Worley, P.; Norman, M. R.; Lott, A.; Salinger, A.; Woodward, C. S.

    2014-12-01

    The recent focus on regional refinement in the Community Atmosphere Model (CAM5) has created a strong need to develop time-stepping methods capable of accelerating throughput on high performance computing for climate dynamics across multiple spatial and temporal scales. This research is focused on developing implicit methods that can be executed at scale on GPU based machines. Efforts to port the scalable spectral element dynamical core to incorporate these developments is presented, including both 2D and 3D benchmark test case results. The current implicit solver and preconditioner implementations utilize a Fortran interface package within the Trilinos project, third party software that allows fully tested, optimized, and robust code with a suite of parameter options to be included a priori. Merging this coding strategy with GPU libraries will be discussed along with beneficial optimization gains and data structure requirements to evaluate Trilinos binded residual calculations on GPU processors.

  3. Frame synchronization in PCM telemetry.

    NASA Technical Reports Server (NTRS)

    Peavey, B.

    1971-01-01

    The frame synchronization performance characteristics are defined that can be measured under actual operating conditions. The frame synchronization process is explained, and test data on the performance of frame synchronizers and frame synchronization codes are presented. The application of frame synchronization methods in specific cases is considered in the light of code selection, frame length, and data recovery.

  4. A new design of ion storage accelerator for time-of-flight-MS

    SciTech Connect

    Kraft, A.; Wollnik, H.; Laiko, V.; Dodonov, A.F.

    1995-12-31

    A new Time-of-Flight MS for orthogonal extraction has been constructed. It consists of a API-source, the orthogonal extraction optic and a single stage reflectron as well as a detector with two MCP`s in Chevron-arrangement. The extraction optic has a new design in respect to the prevention of disturbing fields. Such fields take influence on the primary beam during accumulation made and causes noise as well as broadening of mass peaks. This fields arises from the penetration of field through the grid between the two stages of the extraction optic. In this construction, this penetration is compensated by the introduction of an additional electrode which is held at the average virtual potential of the separation grid. By adjusting all electrical parameters of the mass spectrometer (extraction-pulser, backplane of reflector, focussing optics) the peakwidth had been optimized. It has been shown the peakwidth strongly depends on the potential of the compensation electrode. The optimal value corresponds in good agreement with the calculated value (1.7V instead of 1.56V). In the case of Gramicidin S (m=1140) a resolving power of 2000 is achieved.

  5. On the high-resolution mass analysis of the product ions in tandem time-of-flight (TOF/TOF) mass spectrometers using a time-dependent re-acceleration technique.

    PubMed

    Kurnosenko, Sergey; Moskovets, Eugene

    2010-01-01

    The time-dependent reacceleration of product ions produced as a result of dissociation of a single precursor ion in a tandem time-of-flight mass spectrometer is considered for the first time. Analytical expressions for the shapes of electric pulses bringing all the kinetic energies of the product ions to the same value are derived for two cases: forward acceleration mode and deceleration, followed by re-acceleration in the reversed direction (reversed mode). Secondary time-of-flight focusing resulting from the re-acceleration in the reversed mode is shown to be mass-dependent and, when averaged over a wide mass range, the focusing is tight enough to provide mass resolution exceeding 10,000. After time-dependent re-acceleration, additional compression of the ion packet width leading to better mass resolution can be obtained by decelerating the ions in a constant field.

  6. Modern Steel Framed Schools.

    ERIC Educational Resources Information Center

    American Inst. of Steel Construction, Inc., New York, NY.

    In view of the cost of structural framing for school buildings, ten steel-framed schools are examined to review the economical advantages of steel for school construction. These schools do not resemble each other in size, shape, arrangement or unit cost; some are original in concept and architecture, and others are conservative. Cost and…

  7. An SDR-Based Real-Time Testbed for GNSS Adaptive Array Anti-Jamming Algorithms Accelerated by GPU.

    PubMed

    Xu, Hailong; Cui, Xiaowei; Lu, Mingquan

    2016-01-01

    Nowadays, software-defined radio (SDR) has become a common approach to evaluate new algorithms. However, in the field of Global Navigation Satellite System (GNSS) adaptive array anti-jamming, previous work has been limited due to the high computational power demanded by adaptive algorithms, and often lack flexibility and configurability. In this paper, the design and implementation of an SDR-based real-time testbed for GNSS adaptive array anti-jamming accelerated by a Graphics Processing Unit (GPU) are documented. This testbed highlights itself as a feature-rich and extendible platform with great flexibility and configurability, as well as high computational performance. Both Space-Time Adaptive Processing (STAP) and Space-Frequency Adaptive Processing (SFAP) are implemented with a wide range of parameters. Raw data from as many as eight antenna elements can be processed in real-time in either an adaptive nulling or beamforming mode. To fully take advantage of the parallelism resource provided by the GPU, a batched method in programming is proposed. Tests and experiments are conducted to evaluate both the computational and anti-jamming performance. This platform can be used for research and prototyping, as well as a real product in certain applications. PMID:26978363

  8. An SDR-Based Real-Time Testbed for GNSS Adaptive Array Anti-Jamming Algorithms Accelerated by GPU.

    PubMed

    Xu, Hailong; Cui, Xiaowei; Lu, Mingquan

    2016-03-11

    Nowadays, software-defined radio (SDR) has become a common approach to evaluate new algorithms. However, in the field of Global Navigation Satellite System (GNSS) adaptive array anti-jamming, previous work has been limited due to the high computational power demanded by adaptive algorithms, and often lack flexibility and configurability. In this paper, the design and implementation of an SDR-based real-time testbed for GNSS adaptive array anti-jamming accelerated by a Graphics Processing Unit (GPU) are documented. This testbed highlights itself as a feature-rich and extendible platform with great flexibility and configurability, as well as high computational performance. Both Space-Time Adaptive Processing (STAP) and Space-Frequency Adaptive Processing (SFAP) are implemented with a wide range of parameters. Raw data from as many as eight antenna elements can be processed in real-time in either an adaptive nulling or beamforming mode. To fully take advantage of the parallelism resource provided by the GPU, a batched method in programming is proposed. Tests and experiments are conducted to evaluate both the computational and anti-jamming performance. This platform can be used for research and prototyping, as well as a real product in certain applications.

  9. An SDR-Based Real-Time Testbed for GNSS Adaptive Array Anti-Jamming Algorithms Accelerated by GPU

    PubMed Central

    Xu, Hailong; Cui, Xiaowei; Lu, Mingquan

    2016-01-01

    Nowadays, software-defined radio (SDR) has become a common approach to evaluate new algorithms. However, in the field of Global Navigation Satellite System (GNSS) adaptive array anti-jamming, previous work has been limited due to the high computational power demanded by adaptive algorithms, and often lack flexibility and configurability. In this paper, the design and implementation of an SDR-based real-time testbed for GNSS adaptive array anti-jamming accelerated by a Graphics Processing Unit (GPU) are documented. This testbed highlights itself as a feature-rich and extendible platform with great flexibility and configurability, as well as high computational performance. Both Space-Time Adaptive Processing (STAP) and Space-Frequency Adaptive Processing (SFAP) are implemented with a wide range of parameters. Raw data from as many as eight antenna elements can be processed in real-time in either an adaptive nulling or beamforming mode. To fully take advantage of the parallelism resource provided by the GPU, a batched method in programming is proposed. Tests and experiments are conducted to evaluate both the computational and anti-jamming performance. This platform can be used for research and prototyping, as well as a real product in certain applications. PMID:26978363

  10. Two-Body Orbit Expansion Due to Time-Dependent Relative Acceleration Rate of the Cosmological Scale Factor

    NASA Astrophysics Data System (ADS)

    Iorio, Lorenzo

    2014-01-01

    By phenomenologically assuming a slow temporal variation of the percent acceleration rate S̈S -1 of the cosmic scale factor S(t), it is shown that the orbit of a local binary undergoes a secular expansion. To first order in the power expansion of S̈S -1 around the present epoch t0, a non-vanishing shift per orbit (Δr) of the two-body relative distance r occurs for eccentric trajectories. A general relativistic expression, which turns out to be cubic in the Hubble parameter H0 at the present epoch, is explicitly calculated for it in the case of matter-dominated epochs with Dark Energy. For a highly eccentric Oort comet orbit with period Pb ≈ 31 Myr, the general relativistic distance shift per orbit turns out to be of the order of (Δr) ≈ 70 km. For the Large Magellanic Cloud, assumed on a bound elliptic orbit around the Milky Way, the shift per orbit is of the order of (Δr) ≈ 2-4 pc. Our result has a general validity since it holds in any cosmological model admitting the Hubble law and a slowly varying S̈S-1(t). More generally, it is valid for an arbitrary Hooke-like extra-acceleration whose "elastic" parameter κ is slowly time-dependent, irrespectively of the physical mechanism which may lead to it. The coefficient κ1 of the first-order term of the power expansion of κ(t) can be preliminarily constrained in a model-independent way down to a κ1 ≤ 2 x 10-13 year-3 level from latest Solar System's planetary observations. The radial velocities of the double lined spectroscopic binary ALPHA Cen AB yield κ1 ≤ 10-8 year-3.

  11. The High Time Resolution Universe Pulsar Survey - XII. Galactic plane acceleration search and the discovery of 60 pulsars

    NASA Astrophysics Data System (ADS)

    Ng, C.; Champion, D. J.; Bailes, M.; Barr, E. D.; Bates, S. D.; Bhat, N. D. R.; Burgay, M.; Burke-Spolaor, S.; Flynn, C. M. L.; Jameson, A.; Johnston, S.; Keith, M. J.; Kramer, M.; Levin, L.; Petroff, E.; Possenti, A.; Stappers, B. W.; van Straten, W.; Tiburzi, C.; Eatough, R. P.; Lyne, A. G.

    2015-07-01

    We present initial results from the low-latitude Galactic plane region of the High Time Resolution Universe pulsar survey conducted at the Parkes 64-m radio telescope. We discuss the computational challenges arising from the processing of the terabyte-sized survey data. Two new radio interference mitigation techniques are introduced, as well as a partially coherent segmented acceleration search algorithm which aims to increase our chances of discovering highly relativistic short-orbit binary systems, covering a parameter space including potential pulsar-black hole binaries. We show that under a constant acceleration approximation, a ratio of data length over orbital period of ≈0.1 results in the highest effectiveness for this search algorithm. From the 50 per cent of data processed thus far, we have redetected 435 previously known pulsars and discovered a further 60 pulsars, two of which are fast-spinning pulsars with periods less than 30 ms. PSR J1101-6424 is a millisecond pulsar whose heavy white dwarf (WD) companion and short spin period of 5.1 ms indicate a rare example of full-recycling via Case A Roche lobe overflow. PSR J1757-27 appears to be an isolated recycled pulsar with a relatively long spin period of 17 ms. In addition, PSR J1244-6359 is a mildly recycled binary system with a heavy WD companion, PSR J1755-25 has a significant orbital eccentricity of 0.09 and PSR J1759-24 is likely to be a long-orbit eclipsing binary with orbital period of the order of tens of years. Comparison of our newly discovered pulsar sample to the known population suggests that they belong to an older population. Furthermore, we demonstrate that our current pulsar detection yield is as expected from population synthesis.

  12. Resolution limitations from detector pulse width and jitter in a linear orthogonal-acceleration time-of-flight mass spectrometer.

    PubMed

    Coles, J N; Guilhaus, M

    1994-08-01

    Recent and ongoing advances in timing electronics together with the development of ionization techniques suited to time-of-flight mass spectrometry (TOF-MS) have contributed to renewed interest in this method of mass analysis. Whereas low resolving powers (m/†m < 500) were once an almost unavoidable drawback in TOF-MS, recent developments in instrument geometries have produced much higher resolving powers for many ion sources. The temporal width of detector pulses and jitter in timing electronics, however, lead to contributions to peak widths that are essentially independent of the mass-analyzer ion optics. The effective detector pulse width (†t d ≈ 1-10 ns typically) can be a limiting factor in the development of high resolution time-of-flight (TOF) instruments with modest drift lengths (∼1 m), It also reduces the mass resolution more seriously for light ions. This article presents a method for distinguishing the instrumental "ion arrival-time" resolution (R o) of a linear TOF mass analyzer from that which is locally measured at a particular mass, limited by the broadening of the detector pulse width and electronics. The method also provides an estimate of †t d, that is useful in determining the temporal performance of the detection system. The model developed here is tested with data from a recently constructed orthogonal-acceleration TOF mass spectrometer equipped with a commercially available transient recorder (a LeCroy 400-Msamplejs digital oscilloscope) from which we obtained R o = 4240 ± 100 [full width at half maximum (FWHM)) and †t d = 3.0 ± 0.1 ns (FWHM).

  13. Accelerated time-of-flight (TOF) PET image reconstruction using TOF bin subsetization and TOF weighting matrix pre-computation

    NASA Astrophysics Data System (ADS)

    Mehranian, Abolfazl; Kotasidis, Fotis; Zaidi, Habib

    2016-02-01

    Time-of-flight (TOF) positron emission tomography (PET) technology has recently regained popularity in clinical PET studies for improving image quality and lesion detectability. Using TOF information, the spatial location of annihilation events is confined to a number of image voxels along each line of response, thereby the cross-dependencies of image voxels are reduced, which in turns results in improved signal-to-noise ratio and convergence rate. In this work, we propose a novel approach to further improve the convergence of the expectation maximization (EM)-based TOF PET image reconstruction algorithm through subsetization of emission data over TOF bins as well as azimuthal bins. Given the prevalence of TOF PET, we elaborated the practical and efficient implementation of TOF PET image reconstruction through the pre-computation of TOF weighting coefficients while exploiting the same in-plane and axial symmetries used in pre-computation of geometric system matrix. In the proposed subsetization approach, TOF PET data were partitioned into a number of interleaved TOF subsets, with the aim of reducing the spatial coupling of TOF bins and therefore to improve the convergence of the standard maximum likelihood expectation maximization (MLEM) and ordered subsets EM (OSEM) algorithms. The comparison of on-the-fly and pre-computed TOF projections showed that the pre-computation of the TOF weighting coefficients can considerably reduce the computation time of TOF PET image reconstruction. The convergence rate and bias-variance performance of the proposed TOF subsetization scheme were evaluated using simulated, experimental phantom and clinical studies. Simulations demonstrated that as the number of TOF subsets is increased, the convergence rate of MLEM and OSEM algorithms is improved. It was also found that for the same computation time, the proposed subsetization gives rise to further convergence. The bias-variance analysis of the experimental NEMA phantom and a clinical

  14. Accelerated time-of-flight (TOF) PET image reconstruction using TOF bin subsetization and TOF weighting matrix pre-computation.

    PubMed

    Mehranian, Abolfazl; Kotasidis, Fotis; Zaidi, Habib

    2016-02-01

    Time-of-flight (TOF) positron emission tomography (PET) technology has recently regained popularity in clinical PET studies for improving image quality and lesion detectability. Using TOF information, the spatial location of annihilation events is confined to a number of image voxels along each line of response, thereby the cross-dependencies of image voxels are reduced, which in turns results in improved signal-to-noise ratio and convergence rate. In this work, we propose a novel approach to further improve the convergence of the expectation maximization (EM)-based TOF PET image reconstruction algorithm through subsetization of emission data over TOF bins as well as azimuthal bins. Given the prevalence of TOF PET, we elaborated the practical and efficient implementation of TOF PET image reconstruction through the pre-computation of TOF weighting coefficients while exploiting the same in-plane and axial symmetries used in pre-computation of geometric system matrix. In the proposed subsetization approach, TOF PET data were partitioned into a number of interleaved TOF subsets, with the aim of reducing the spatial coupling of TOF bins and therefore to improve the convergence of the standard maximum likelihood expectation maximization (MLEM) and ordered subsets EM (OSEM) algorithms. The comparison of on-the-fly and pre-computed TOF projections showed that the pre-computation of the TOF weighting coefficients can considerably reduce the computation time of TOF PET image reconstruction. The convergence rate and bias-variance performance of the proposed TOF subsetization scheme were evaluated using simulated, experimental phantom and clinical studies. Simulations demonstrated that as the number of TOF subsets is increased, the convergence rate of MLEM and OSEM algorithms is improved. It was also found that for the same computation time, the proposed subsetization gives rise to further convergence. The bias-variance analysis of the experimental NEMA phantom and a clinical

  15. Red Blood Cell Membrane as a Biomimetic Nanocoating for Prolonged Circulation Time and Reduced Accelerated Blood Clearance.

    PubMed

    Rao, Lang; Bu, Lin-Lin; Xu, Jun-Hua; Cai, Bo; Yu, Guang-Tao; Yu, Xiaolei; He, Zhaobo; Huang, Qinqin; Li, Andrew; Guo, Shi-Shang; Zhang, Wen-Feng; Liu, Wei; Sun, Zhi-Jun; Wang, Hao; Wang, Tza-Huei; Zhao, Xing-Zhong

    2015-12-01

    For decades, poly(ethylene glycol) (PEG) has been widely incorporated into nanoparticles for evading immune clearance and improving the systematic circulation time. However, recent studies have reported a phenomenon known as "accelerated blood clearance (ABC)" where a second dose of PEGylated nanomaterials is rapidly cleared when given several days after the first dose. Herein, we demonstrate that natural red blood cell (RBC) membrane is a superior alternative to PEG. Biomimetic RBC membrane-coated Fe(3)O(4) nanoparticles (Fe(3)O(4) @RBC NPs) rely on CD47, which is a "don't eat me" marker on the RBC surface, to escape immune clearance through interactions with the signal regulatory protein-alpha (SIRP-α) receptor. Fe(3)O(4) @RBC NPs exhibit extended circulation time and show little change between the first and second doses, with no ABC suffered. In addition, the administration of Fe(3)O(4) @RBC NPs does not elicit immune responses on neither the cellular level (myeloid-derived suppressor cells (MDSCs)) nor the humoral level (immunoglobulin M and G (IgM and IgG)). Finally, the in vivo toxicity of these cell membrane-camouflaged nanoparticles is systematically investigated by blood biochemistry, hematology testing, and histology analysis. These findings are significant advancements toward solving the long-existing clinical challenges of developing biomaterials that are able to resist both immune response and rapid clearance. PMID:26488923

  16. Structure and composition of the distant lunar exosphere: Constraints from ARTEMIS observations of ion acceleration in time-varying fields

    NASA Astrophysics Data System (ADS)

    Halekas, J. S.; Poppe, A. R.; Farrell, W. M.; McFadden, J. P.

    2016-06-01

    By analyzing the trajectories of ionized constituents of the lunar exosphere in time-varying electromagnetic fields, we can place constraints on the composition, structure, and dynamics of the lunar exosphere. Heavy ions travel slower than light ions in the same fields, so by observing the lag between field rotations and the response of ions from the lunar exosphere, we can place constraints on the composition of the ions. Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) provides an ideal platform to utilize such an analysis, since its two-probe vantage allows precise timing of the propagation of field discontinuities in the solar wind, and its sensitive plasma instruments can detect the ion response. We demonstrate the utility of this technique by using fully time-dependent charged particle tracing to analyze several minutes of ion observations taken by the two ARTEMIS probes ~3000-5000 km above the dusk terminator on 25 January 2014. The observations from this time period allow us to reach several interesting conclusions. The ion production at altitudes of a few hundred kilometers above the sunlit surface of the Moon has an unexpectedly significant contribution from species with masses of 40 amu or greater. The inferred distribution of the neutral source population has a large scale height, suggesting that micrometeorite impact vaporization and/or sputtering play an important role in the production of neutrals from the surface. Our observations also suggest an asymmetry in ion production, consistent with either a compositional variation in neutral vapor production or a local reduction in solar wind sputtering in magnetic regions of the surface.

  17. Real-time atomic-resolution imaging of crystal growth process in water by phase modulation atomic force microscopy at one frame per second

    SciTech Connect

    Miyata, Kazuki; Asakawa, Hitoshi; Fukuma, Takeshi

    2013-11-11

    Recent advancement in dynamic-mode atomic force microscopy (AFM) has enabled its operation in liquid with atomic-scale resolution. However, its imaging speed has often been too slow to visualize atomic-scale dynamic processes. Here, we propose a method for making a significant improvement in the operation speed of dynamic-mode AFM. In this method, we use a wideband and low-latency phase detector with an improved algorithm for the signal complexification. We demonstrate atomic-scale imaging of a calcite crystal growth process in water at one frame per second. The significant improvement in the imaging speed should enable various studies on unexplored atomic-scale interfacial processes.

  18. Section at Frame 195, Section at Frame 154, Section at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Section at Frame 195, Section at Frame 154, Section at Midship, Section at Frame 45, Longitudinal Section at Reinforced Bow Structure - US Coast Guard Icebreaker Glacier, Suisun Bay Reserve Fleet, Benicia, Solano County, CA

  19. Celestial Reference Frames

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher S.

    2013-03-01

    Concepts and Background: This paper gives an overview of modern celestial reference frames as realized at radio frequencies using the Very Long baseline Interferometry (VLBI) technique. We discuss basic celestial reference frame concepts, desired properties, and uses. We review the networks of antennas used for this work. We briefly discuss the history of the science of astrometry touching upon the discovery of precession, proper motion, nutation, and parallax, and the field of radio astronomy. Building Celestial Frames: Next, we discuss the multi-step process of building a celestial frame: First candidate sources are identified based on point-like properties from single dish radio telescopes surveys. Second, positions are refined using connected element interferometers such as the Very Large Array, and the ATCA. Third, positions of approximately milli-arcsecond (mas) accuracy are determined using intercontinental VLBI surveys. Fourth, sub-mas positions are determined by multiyear programs using intercontinental VLBI. These sub-mas sets of positions are then verified by multiple teams in preparation for release to non-specialists in the form of an official IAU International Celestial Reference Frame (ICRF). The process described above has until recently been largely restricted to work at S/X-band (2.3/8.4 GHz). However, in the last decade sub-mas work has expanded to include celestial frames at K-band (24 GHz), Ka-band (32 GHz), and Q-band (43 GHz). While these frames currently have the disadvantage of far smaller data sets, the astrophysical quality of the sources themselves improves at these higher frequencies and thus make these frequencies attractive for realizations of celestial reference frames. Accordingly, we review progress at these higher frequency bands. Path to the Future: We discuss prospects for celestial reference frames over the next decade. We present an example of an error budget for astrometric VLBI and discuss the budget's use as a tool for

  20. Celestial Reference Frame

    NASA Astrophysics Data System (ADS)

    Jacobs, Christopher S.

    2013-09-01

    Concepts and Background: This paper gives an overview of modern celestial reference frames as realized at radio frequencies using the Very Long baseline Interferometry (VLBI) technique. We discuss basic celestial reference frame concepts, desired properties, and uses. We review the networks of antennas used for this work. We briefly discuss the history of the science of astrometry touching upon the discovery of precession, proper motion, nutation, and parallax, and the field of radio astronomy. Building Celestial Frames: Next, we discuss the multi-step process of building a celestial frame: First candidate sources are identified based on point-like properties from single dish radio telescopes surveys. Second, positions are refined using connected element interferometers such as the Very Large Array, and the ATCA. Third, positions of approximately milli-arcsecond (mas) accuracy are determined using intercontinental VLBI surveys. Fourth, sub-mas positions are determined by multiyear programs using intercontinental VLBI. These sub-mas sets of positions are then verified by multiple teams in preparation for release to non-specialists in the form of an official IAU International Celestial Reference Frame (ICRF). The process described above has until recently been largely restricted to work at S/X-band (2.3/8.4 GHz). However, in the last decade sub-mas work has expanded to include celestial frames at K-band (24 GHz), Ka-band (32 GHz), and Q-band (43 GHz). While these frames currently have the disadvantage of far smaller data sets, the astrophysical quality of the sources themselves improves at these higher frequencies and thus make these frequencies attractive for realizations of celestial reference frames. Accordingly, we review progress at these higher frequency bands. Path to the Future: We discuss prospects for celestial reference frames over the next decade. We present an example of an error budget for astrometric VLBI and discuss the budget's use as a tool for

  1. APT/LEDA RFQ and support frame structural analysis

    SciTech Connect

    Ellis, S.

    1997-04-01

    This report documents structural analysis of the Accelerator Production of Tritium Low Energy Demonstration Accelerator (APT/LEDA) Radio Frequency Quadrupole (RFQ) accelerator structure and its associated support frame. This work was conducted for the Department of Energy in support of the APT/LEDA. Structural analysis of the RFQ was performed to quantify stress levels and deflections due to both vacuum loading and gravity loading. This analysis also verified the proposed support scheme geometry and quantified interface loads. This analysis also determined the necessary stiffness and strength requirements of the RFQ support frame verifying the conceptual design geometry and allowing specification of individual frame elements. Complete structural analysis of the frame was completed subsequently. This report details structural analysis of the RFQ assembly with regard to gravity and vacuum loads only. Thermally induced stresses from the Radio Frequency (RF) surface resistance heating were not considered.

  2. Detection of large ions in time-of-flight mass spectrometry: effects of ion mass and acceleration voltage on microchannel plate detector response.

    PubMed

    Liu, Ranran; Li, Qiyao; Smith, Lloyd M

    2014-08-01

    In time-of-flight mass spectrometry (TOF-MS), ion detection is typically accomplished by the generation and amplification of secondary electrons produced by ions colliding with a microchannel plate (MCP) detector. Here, the response of an MCP detector as a function of ion mass and acceleration voltage is characterized, for singly charged peptide/protein ions ranging from 1 to 290 kDa in mass, and for acceleration voltages from 5 to 25 kV. A nondestructive inductive charge detector (ICD) employed in parallel with MCP detection provides a reliable reference signal to allow accurate calibration of the MCP response. MCP detection efficiencies were very close to unity for smaller ions at high acceleration voltages (e.g., angiotensin, 1046.5 Da, at 25 kV acceleration voltage), but decreased to ~11% for the largest ions examined (immunoglobulin G (IgG) dimer, 290 kDa) even at the highest acceleration voltage employed (25 kV). The secondary electron yield γ (average number of electrons produced per ion collision) is found to be proportional to mv(3.1) (m: ion mass, v: ion velocity) over the entire mass range examined, and inversely proportional to the square root of m in TOF-MS analysis. The results indicate that although MCP detectors indeed offer superlative performance in the detection of smaller peptide/protein species, their performance does fall off substantially for larger proteins, particularly under conditions of low acceleration voltage.

  3. Accelerators, Beams And Physical Review Special Topics - Accelerators And Beams

    SciTech Connect

    Siemann, R.H.; /SLAC

    2011-10-24

    Accelerator science and technology have evolved as accelerators became larger and important to a broad range of science. Physical Review Special Topics - Accelerators and Beams was established to serve the accelerator community as a timely, widely circulated, international journal covering the full breadth of accelerators and beams. The history of the journal and the innovations associated with it are reviewed.

  4. Particle acceleration

    NASA Technical Reports Server (NTRS)

    Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.; Alissandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.; Ellison, D.

    1986-01-01

    Data is compiled from Solar Maximum Mission and Hinothori satellites, particle detectors in several satellites, ground based instruments, and balloon flights in order to answer fundamental questions relating to: (1) the requirements for the coronal magnetic field structure in the vicinity of the energization source; (2) the height (above the photosphere) of the energization source; (3) the time of energization; (4) transistion between coronal heating and flares; (5) evidence for purely thermal, purely nonthermal and hybrid type flares; (6) the time characteristics of the energization source; (7) whether every flare accelerates protons; (8) the location of the interaction site of the ions and relativistic electrons; (9) the energy spectra for ions and relativistic electrons; (10) the relationship between particles at the Sun and interplanetary space; (11) evidence for more than one acceleration mechanism; (12) whether there is single mechanism that will accelerate particles to all energies and also heat the plasma; and (13) how fast the existing mechanisms accelerate electrons up to several MeV and ions to 1 GeV.

  5. Linear Accelerators

    SciTech Connect

    Sidorin, Anatoly

    2010-01-05

    In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

  6. A new limit on the time between the nucleosynthesis and the acceleration of cosmic rays in supernova remnants using the Co/Ni ratio

    NASA Technical Reports Server (NTRS)

    Webber, W. R.; Gupta, M.

    1990-01-01

    Using new cross section measurements of Ni into Co, data on the Co/Ni ratio in cosmic rays from the HEAO C spacecraft have been reinterpreted in terms of the time between nucleosynthesis and the acceleration of cosmic rays, delta t. The observed Co/Ni ratio is now consistent with interstellar fragmentation only, leading to a small or zero source abundance. In terms of the decay of e-process nucleosynthesis nuclides into Co after a supernova explosion, this permits an estimate of delta t = 4-30,000 yr for the time between nucleosynthesis and the acceleration of cosmic rays if supernovae are the direct progenitors of cosmic rays. These age limits are used in conjunction with models of the expansion of supernova remnants (SNRs), to estimate that cosmic rays are accelerated when the radius of these remnants is between 0.1 and 25 pc.

  7. Efficient key frames selection for panorama generation from video

    NASA Astrophysics Data System (ADS)

    Fadaeieslam, Mohammad Javad; Soryani, Mohsen; Fathy, Mahmood

    2011-04-01

    A video sequence consists of several hundred frames, and as a result, creating a panoramic image from these frames is a very time-consuming process. Consecutive frames have large overlap areas that do not provide much information. Therefore, some key frames must be extracted for better performance. There are a number of methods for key-frame selection that match all frames in a video sequence. We present a novel and efficient method to select key frames from video for creating a large panoramic mosaic without matching all frames. Consecutive frames are transformed and projected onto the common mosaic surface and the position of each corner of the next frame is predicted with a distinct Kalman filter on this surface. The overlap area between each predicted frame and its previous key frame is used as the criterion to select the next key frame. This method uses video information to reduce features and align frames with repeated structures more accurately. We show that this approach is an efficient preprocessing step and substantially reduces the time required to construct panorama from a video sequence.

  8. Improved quality of intrafraction kilovoltage images by triggered readout of unexposed frames

    SciTech Connect

    Poulsen, Per Rugaard; Jonassen, Johnny; Jensen, Carsten; Schmidt, Mai Lykkegaard

    2015-11-15

    Purpose: The gantry-mounted kilovoltage (kV) imager of modern linear accelerators can be used for real-time tumor localization during radiation treatment delivery. However, the kV image quality often suffers from cross-scatter from the megavoltage (MV) treatment beam. This study investigates readout of unexposed kV frames as a means to improve the kV image quality in a series of experiments and a theoretical model of the observed image quality improvements. Methods: A series of fluoroscopic images were acquired of a solid water phantom with an embedded gold marker and an air cavity with and without simultaneous radiation of the phantom with a 6 MV beam delivered perpendicular to the kV beam with 300 and 600 monitor units per minute (MU/min). An in-house built device triggered readout of zero, one, or multiple unexposed frames between the kV exposures. The unexposed frames contained part of the MV scatter, consequently reducing the amount of MV scatter accumulated in the exposed frames. The image quality with and without unexposed frame readout was quantified as the contrast-to-noise ratio (CNR) of the gold marker and air cavity for a range of imaging frequencies from 1 to 15 Hz. To gain more insight into the observed CNR changes, the image lag of the kV imager was measured and used as input in a simple model that describes the CNR with unexposed frame readout in terms of the contrast, kV noise, and MV noise measured without readout of unexposed frames. Results: Without readout of unexposed kV frames, the quality of intratreatment kV images decreased dramatically with reduced kV frequencies due to MV scatter. The gold marker was only visible for imaging frequencies ≥3 Hz at 300 MU/min and ≥5 Hz for 600 MU/min. Visibility of the air cavity required even higher imaging frequencies. Readout of multiple unexposed frames ensured visibility of both structures at all imaging frequencies and a CNR that was independent of the kV frame rate. The image lag was 12.2%, 2

  9. How Constant Momentum Acceleration Decouples Energy and Space Focusing in Distance-of-Flight and Time-of-Flight Mass Spectrometries

    SciTech Connect

    Dennis, Elise; Gundlach-Graham, Alexander W.; Enke, Chris; Ray, Steven J.; Carado, Anthony J.; Barinaga, Charles J.; Koppenaal, David W.; Hieftje, Gary M.

    2013-05-01

    Time-of-flight (TOF) and distance-of-flight (DOF) mass spectrometers require means for focusing ions at the detector(s) because of initial dispersions of position and energy at the time of their acceleration. Time-of-flight mass spectrometers ordinarily employ constant energy acceleration (CEA), which creates a space-focus plane at which the initial spatial dispersion is corrected. In contrast, constant-momentum acceleration (CMA), in conjunction with an ion mirror, provides focus of the initial energy dispersion at the energy focus time for ions of all m/z at their respective positions along the flight path. With CEA, the initial energy dispersion is not simultaneously correctable as its effect on ion velocity is convoluted with that of the spatial dispersion. The initial spatial dispersion with CMA remains unchanged throughout the field-free region of the flight path, so spatial dispersion can be reduced before acceleration. Improved focus is possible when each dispersion can be addressed independently. With minor modification, a TOF mass spectrometer can be operated in CMA mode by treating the TOF detector as though it were a single element in the array of detectors that would be used in a DOF mass spectrometer. Significant improvement in mass resolution is thereby achieved, albeit over a narrow range of m/z values. In this paper, experimental and theoretical results are presented that illustrate the energy-focusing capabilities of both DOF and TOF mass spectrometry.

  10. Analyzing Factors Affecting Emergency Department Length of Stay-Using a Competing Risk-accelerated Failure Time Model.

    PubMed

    Chaou, Chung-Hsien; Chiu, Te-Fa; Yen, Amy Ming-Fang; Ng, Chip-Jin; Chen, Hsiu-Hsi

    2016-04-01

    Emergency department (ED) length of stay (LOS) is associated with ED crowding and related complications. Previous studies either analyzed single patient disposition groups or combined different endpoints as a whole. The aim of this study is to evaluate different effects of relevant factors affecting ED LOS among different patient disposition groups.This is a retrospective electronic data analysis. The ED LOS and relevant covariates of all patients between January 2013 and December 2013 were collected. A competing risk accelerated failure time model was used to compute endpoint type-specific time ratios (TRs) for ED LOS.A total of 149,472 patients was included for analysis with an overall medium ED LOS of 2.15 [interquartile range (IQR) = 6.51] hours. The medium LOS for discharged, admission, and mortality patients was 1.46 (IQR = 2.07), 11.3 (IQR = 33.2), and 7.53 (IQR = 28.0) hours, respectively. In multivariate analysis, age (TR = 1.012, P < 0.0001], higher acuity (triage level I vs level V, TR = 2.371, P < 0.0001), pediatric nontrauma (compared with adult nontrauma, TR = 3.084, P < 0.0001), transferred patients (TR = 2.712, P < 0.0001), and day shift arrival (compared with night shift, TR = 1.451, P < 0.0001) were associated with prolonged ED LOS in the discharged patient group. However, opposite results were noted for higher acuity (triage level I vs level V, TR = 0.532, P < 0.0001), pediatric nontrauma (TR = 0.375, P < 0.0001), transferred patients (TR = 0.852, P < 0.0001), and day shift arrival (TR = 0.88, P < 0.0001) in the admission patient group.Common influential factors such as age, patient entity, triage acuity level, or arrival time may have varying effects on different disposition groups of patients. These findings and the suggested model could be used for EDs to develop individually tailored approaches to minimize ED LOS and further improve ED crowding status

  11. Analyzing Factors Affecting Emergency Department Length of Stay—Using a Competing Risk-accelerated Failure Time Model

    PubMed Central

    Chaou, Chung-Hsien; Chiu, Te-Fa; Yen, Amy Ming-Fang; Ng, Chip-Jin; Chen, Hsiu-Hsi

    2016-01-01

    Abstract Emergency department (ED) length of stay (LOS) is associated with ED crowding and related complications. Previous studies either analyzed single patient disposition groups or combined different endpoints as a whole. The aim of this study is to evaluate different effects of relevant factors affecting ED LOS among different patient disposition groups. This is a retrospective electronic data analysis. The ED LOS and relevant covariates of all patients between January 2013 and December 2013 were collected. A competing risk accelerated failure time model was used to compute endpoint type-specific time ratios (TRs) for ED LOS. A total of 149,472 patients was included for analysis with an overall medium ED LOS of 2.15 [interquartile range (IQR) = 6.51] hours. The medium LOS for discharged, admission, and mortality patients was 1.46 (IQR = 2.07), 11.3 (IQR = 33.2), and 7.53 (IQR = 28.0) hours, respectively. In multivariate analysis, age (TR = 1.012, P < 0.0001], higher acuity (triage level I vs level V, TR = 2.371, P < 0.0001), pediatric nontrauma (compared with adult nontrauma, TR = 3.084, P < 0.0001), transferred patients (TR = 2.712, P < 0.0001), and day shift arrival (compared with night shift, TR = 1.451, P < 0.0001) were associated with prolonged ED LOS in the discharged patient group. However, opposite results were noted for higher acuity (triage level I vs level V, TR = 0.532, P < 0.0001), pediatric nontrauma (TR = 0.375, P < 0.0001), transferred patients (TR = 0.852, P < 0.0001), and day shift arrival (TR = 0.88, P < 0.0001) in the admission patient group. Common influential factors such as age, patient entity, triage acuity level, or arrival time may have varying effects on different disposition groups of patients. These findings and the suggested model could be used for EDs to develop individually tailored approaches to minimize ED LOS and further improve ED crowding

  12. Design, Simulation and Testing of a Precision Alignment Frame for the Next Linear Collider

    SciTech Connect

    Fitsos, P

    2004-06-18

    An alignment frame is developed to support 3 Beam Position Monitors (BPM's) for detecting and ultimately aligning the electron beam from a linear accelerator. This report discusses the design details, preliminary modal analysis of the alignment frame as well as the addition of a metrology frame in the final phase of development.

  13. Performance optimisation of a new-generation orthogonal-acceleration quadrupole-time-of-flight mass spectrometer.

    PubMed

    Bristow, Tony; Constantine, Jill; Harrison, Mark; Cavoit, Fabien

    2008-04-01

    Orthogonal-acceleration quadrupole time-of-flight (oa-QTOF) mass spectrometers, employed for accurate mass measurement, have been commercially available for well over a decade. A limitation of the early instruments of this type was the narrow ion abundance range over which accurate mass measurements could be made with a high degree of certainty. Recently, a new generation of oa-QTOF mass spectrometers has been developed and these allow accurate mass measurements to be recorded over a much greater range of ion abundances. This development has resulted from new ion detection technology and improved electronic stability or by accurate control of the number of ions reaching the detector. In this report we describe the results from experiments performed to evaluate the mass measurement performance of the Bruker micrOTOF-Q, a member of the new-generation oa-QTOFs. The relationship between mass accuracy and ion abundance has been extensively evaluated and mass measurement accuracy remained stable (+/-1.5 m m/z units) over approximately 3-4 orders of magnitude of ion abundance. The second feature of the Bruker micrOTOF-Q that was evaluated was the SigmaFit function of the software. This isotope pattern-matching algorithm provides an exact numerical comparison of the theoretical and measured isotope patterns as an additional identification tool to accurate mass measurement. The smaller the value, the closer the match between theoretical and measured isotope patterns. This information is then employed to reduce the number of potential elemental formulae produced from the mass measurements. A relationship between the SigmaFit value and ion abundance has been established. The results from the study for both mass accuracy and SigmaFit were employed to define the performance criteria for the micrOTOF-Q. This provided increased confidence in the selection of elemental formulae resulting from accurate mass measurements.

  14. Potential of gas chromatography-orthogonal acceleration time-of-flight mass spectrometry (GC-oaTOFMS) in flavor research.

    PubMed

    Fay, Laurent B; Newton, Anthony; Simian, Hervé; Robert, Fabien; Douce, David; Hancock, Peter; Green, Martin; Blank, Imre

    2003-04-23

    Gas chromatography-orthogonal acceleration time-of-flight mass spectrometry (GC-oaTOFMS) is an emerging technique offering a straightforward access to a resolving power up to 7000. This paper deals with the use of GC-oaTOFMS to identify the flavor components of a complex seafood flavor extract and to quantify furanones formed in model Maillard reactions. A seafood extract was selected as a representative example for complex food flavors and was previously analyzed using GC-quadrupole MS, leaving several molecules unidentified. GC-oaTOFMS analysis was focused on these unknowns to evaluate its potential in flavor research, particularly for determining exact masses. N-Methyldithiodimethylamine, 6-methyl-5-hepten-2-one, and tetrahydro-2,4-dimethyl-4H-pyrrolo[2,1-d]-1,3,5-dithiazine were successfully identified on the basis of the precise mass determination of their molecular ions and their major fragments. A second set of experiments was performed to test the capabilities of the GC-oaTOFMS for quantification. Calibration curves were found to be linear over a dynamic range of 10(3) for the quantification of furanones. The quantitative data obtained using GC-oaTOFMS confirmed earlier results that the formation of 4-hydroxy-2,5-dimethyl-3(2H)-furanone was favored in the xylose/glycine model reaction and 2(or 5)-ethyl-4-hydroxy-5(or 2)-methyl-3(2H)-furanone in the xylose/alanine model reaction. It was concluded that GC-oaTOFMS may become a powerful analytical tool for the flavor chemist for both identification and quantification purposes, the latter in particular when combined with stable isotope dilution assay.

  15. Fast-acting calorimeter measures heat output of plasma gun accelerator

    NASA Technical Reports Server (NTRS)

    Dethlefson, R.; Larson, A. V.; Liebing, L.

    1967-01-01

    Calorimeter measures the exhaust energy from a shot of a pulsed plasma gun accelerator. It has a fast response time and requires only one measurement to determine the total energy. It uses a long ribbon of copper foil wound around a glass frame to form a reentrant cavity.

  16. BrainFrame: a knowledge visualization system for the neurosciences

    NASA Astrophysics Data System (ADS)

    Barnes, Steven J.; Shaw, Chris D.

    2009-01-01

    Neuroscience has benefited from an explosion of new experimental techniques; many have only become feasible in the wake of improvements in computing speed and data storage. At the same time, these new computation-intensive techniques have led to a growing gulf between the data and the knowledge extracted from those data. That is, in the neurosciences there is a paucity of effective knowledge management techniques and an accelerating accumulation of experimental data. The purpose of the project described in the present paper is to create a visualization of the knowledge base of the neurosciences. At run-time, this 'BrainFrame' project accesses several web-based ontologies and generates a semantically zoomable representation of any one of many levels of the human nervous system.

  17. Radiation from violently accelerated bodies

    NASA Astrophysics Data System (ADS)

    Gerlach, Ulrich H.

    2001-11-01

    A determination is made of the radiation emitted by a linearly uniformly accelerated uncharged dipole transmitter. It is found that, first of all, the radiation rate is given by the familiar Larmor formula, but it is augmented by an amount which becomes dominant for sufficiently high acceleration. For an accelerated dipole oscillator, the criterion is that the center of mass motion become relativistic within one oscillation period. The augmented formula and the measurements which it summarizes presuppose an expanding inertial observation frame. A static inertial reference frame will not do. Secondly, it is found that the radiation measured in the expanding inertial frame is received with 100% fidelity. There is no blueshift or redshift due to the accelerative motion of the transmitter. Finally, it is found that a pair of coherently radiating oscillators accelerating (into opposite directions) in their respective causally disjoint Rindler-coordinatized sectors produces an interference pattern in the expanding inertial frame. Like the pattern of a Young double slit interferometer, this Rindler interferometer pattern has a fringe spacing which is inversely proportional to the proper separation and the proper frequency of the accelerated sources. The interferometer, as well as the augmented Larmor formula, provide a unifying perspective. It joins adjacent Rindler-coordinatized neighborhoods into a single spacetime arena for scattering and radiation from accelerated bodies.

  18. Can Accelerators Accelerate Learning?

    NASA Astrophysics Data System (ADS)

    Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

    2009-03-01

    The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ) [1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

  19. Can Accelerators Accelerate Learning?

    SciTech Connect

    Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

    2009-03-10

    The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ)[1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

  20. Informative-frame filtering in endoscopy videos

    NASA Astrophysics Data System (ADS)

    An, Yong Hwan; Hwang, Sae; Oh, JungHwan; Lee, JeongKyu; Tavanapong, Wallapak; de Groen, Piet C.; Wong, Johnny

    2005-04-01

    Advances in video technology are being incorporated into today"s healthcare practice. For example, colonoscopy is an important screening tool for colorectal cancer. Colonoscopy allows for the inspection of the entire colon and provides the ability to perform a number of therapeutic operations during a single procedure. During a colonoscopic procedure, a tiny video camera at the tip of the endoscope generates a video signal of the internal mucosa of the colon. The video data are displayed on a monitor for real-time analysis by the endoscopist. Other endoscopic procedures include upper gastrointestinal endoscopy, enteroscopy, bronchoscopy, cystoscopy, and laparoscopy. However, a significant number of out-of-focus frames are included in this type of videos since current endoscopes are equipped with a single, wide-angle lens that cannot be focused. The out-of-focus frames do not hold any useful information. To reduce the burdens of the further processes such as computer-aided image processing or human expert"s examinations, these frames need to be removed. We call an out-of-focus frame as non-informative frame and an in-focus frame as informative frame. We propose a new technique to classify the video frames into two classes, informative and non-informative frames using a combination of Discrete Fourier Transform (DFT), Texture Analysis, and K-Means Clustering. The proposed technique can evaluate the frames without any reference image, and does not need any predefined threshold value. Our experimental studies indicate that it achieves over 96% of four different performance metrics (i.e. precision, sensitivity, specificity, and accuracy).

  1. Aluminum space frame technology

    SciTech Connect

    Birch, S.

    1994-01-01

    This article examines the increased application of aluminum to the construction of automobile frames. The topics of the article include a joint venture between Audi and Alcoa, forms in which aluminum is used, new alloys and construction methods, meeting rigidity and safety levels, manufacturing techniques, the use of extrusions, die casting, joining techniques, and pollution control during manufacturing.

  2. Framing Evolution Discussion Intellectually

    ERIC Educational Resources Information Center

    Oliveira, Alandeom W.; Cook, Kristin; Buck, Gayle A.

    2011-01-01

    This study examines how a first-year biology teacher facilitates a series of whole-class discussions about evolution during the implementation of a problem-based unit. A communicative theoretical perspective is adopted wherein evolution discussions are viewed as social events that the teacher can frame intellectually (i.e., present or organize as…

  3. Popcorn Story Frames.

    ERIC Educational Resources Information Center

    DiLella, Carol Ann

    This paper presents "popcorn story frames"--holistic outlines that facilitate comprehension when reading and writing stories, useful for outlining stories read and for creating outlines for original student stories--that are particularly useful for elementary and intermediate school students. "Popcorn" pops in a horizontal manner rather than in a…

  4. Frame dragging and superenergy

    SciTech Connect

    Herrera, L.; Di Prisco, A.; Carot, J.

    2007-08-15

    We show that the vorticity appearing in stationary vacuum spacetimes is always related to the existence of a flow of superenergy on the plane orthogonal to the vorticity vector. This result, together with the previously established link between vorticity and superenergy in radiative (Bondi-Sachs) spacetimes, strengthens further the case for this latter quantity as the cause of frame dragging.

  5. Nighttime Clouds in Martian Arctic (Accelerated Movie)

    NASA Technical Reports Server (NTRS)

    2008-01-01

    An angry looking sky is captured in a movie clip consisting of 10 frames taken by the Surface Stereo Imager on NASA's Phoenix Mars Lander.

    The clip accelerates the motion. The images were take around 3 a.m. local solar time at the Phoenix site during Sol 95 (Aug. 30), the 95th Martian day since landing.

    The swirling clouds may be moving generally in a westward direction over the lander.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  6. Disformal gravity theories: A Jordan frame analysis

    NASA Astrophysics Data System (ADS)

    Sakstein, Jeremy; Verner, Sarunas

    2015-12-01

    The Jordan frame action for general disformal theories is presented and studied for the first time, motivated by several unresolved mysteries that arise when working in the Einstein frame. We present the Friedmann equations and, specializing to exponential functions, study the late-time cosmology using both dynamical systems methods and by finding approximate solutions. Our analysis reveals that either the disformal effects are irrelevant or the Universe evolves towards a phantom phase where the equation of state of dark energy is -3 . There is a marginal case where the asymptotic state of the Universe depends on the model parameters and de Sitter solutions can be obtained. Our findings indicate that the metric singularity found using the Einstein frame construction corresponds to phantom behavior in the Jordan frame and we argue that this is the case for general disformal theories.

  7. Are Transition Periods the Optimal Time for Acceleration? The Training of a First Order Conservation in Young Children.

    ERIC Educational Resources Information Center

    Biskin, Donald S.; Rice, Deborah

    The effectiveness of acceleration training with children who were in a transition period was examined. Forty-eight kindergarten children were separated into four groups on the basis of their status (Preoperational vs. Transitional) and whether or not they received three sessions of inversion-negation training. The results of the immediate and…

  8. Effect of non-structural elements on the dynamic behaviour of moment-resisting framed structures

    NASA Astrophysics Data System (ADS)

    Carlo Ponzo, Felice; Ditommaso, Rocco; Auletta, Gianluca

    2015-04-01

    Effects of earthquakes on building structures have studied from many researchers on the recent scientific and technique literature. The phenomenon is clear: inertia forces are governed from structural and non-structural stiffness and masses. The distribution of seismic lateral loads and their magnitude are strongly correlated to the fundamental period of the structure. Therefore, an accurate evaluation of the fundamental period is a crucial aspect for both static and dynamic seismic analyses. In fact, the fundamental period determines the global seismic demand through the spectral acceleration directly evaluated from the linear and/or nonlinear acceleration response spectra (provided from codes or derived from detailed analyses of site effects). Recent earthquakes highlighted the significant effects derived from the interaction between structural and non-structural elements on the main dynamic parameters of a structure and on the lateral distribution of the inertial forces. Usually, non-structural elements acts together with the structural elements, adding both masses and stiffness. Using numerical and experimental campaigns, many researchers have studied the effects of infill walls on the dynamic behaviour of buildings and several simplified models have been proposed to take into account the presence of non-structural elements within linear and nonlinear numerical models. As example, Kliner and Bertero tested a 1/3 scaled structure (moment-resisting infilled frame model) and determine its behaviour during earthquakes. They found that the infills increased the stiffness of the frame in about 5 times. Consequently, in these cases the fundamental period reduces and the inertia forces generally increases. Meharabi et al. tested a 6-storey, three bay, reinforced concrete moment resisting frame, designed according to the provision of UBC-91, and they shown that the lateral force resistance of an infilled frame was higher than that of bare frame. It was concluded that a

  9. Effect of cross exercise on quadriceps acceleration reaction time and subjective scores (Lysholm questionnaire) following anterior cruciate ligament reconstruction

    PubMed Central

    Papandreou, Maria G; Billis, Evdokia V; Antonogiannakis, Emmanouel M; Papaioannou, Nikos A

    2009-01-01

    Background Anterior cruciate ligament (ACL) injury or reconstruction can cause knee impairments and disability. Knee impairments are related to quadriceps performance – accelerated reaction time (ART) – and disability to performance of daily living activities which is assessed by questionnaires such as the Lysholm knee score. The purposes of this study were to investigate the effect of cross exercise, as supplementary rehabilitation to the early phase of ACL reconstruction: a) on quadriceps ART at the angles 45°, 60° and 90° of knee flexion and, b) on the subjective scores of disability in ACL reconstructed patients. Methods 42 patients who underwent ACL reconstruction were randomly divided into 3 groups, two experimental and one control. All groups followed the same rehabilitation program. The experimental groups followed 8 weeks of cross eccentric exercise (CEE) on the uninjured knee; 3 d/w, and 5 d/w respectively. Quadriceps ART was measured at 45°, 60° and 90° of knee flexion pre and nine weeks post-operatively using an isokinetic dynamometer. Patients also completed pre and post operatively the Lysholm questionnaire whereby subjective scores were recorded. Results Two factor ANOVA showed significant differences in ART at 90° among the groups (F = 4.29, p = 0.02, p < 0.05). Post hoc Tukey HSD analysis determined that the significant results arose from the first experimental group in comparison to the control (D = -0.83, p = 0.01). No significant differences were revealed at 45° and 60°. Significant differences were also found in the Lysholm score among the groups (F = 4.75, p = 0.01, p < 0.05). Post hoc analysis determined that the above significant results arose from the first experimental group in comparison with the control (D = 7.5, p < 0.01) and from the second experimental in comparison with the control (D = 3.78, p = 0.03). Conclusion CEE showed improvements on quadriceps ART at 90° at a sequence of 3 d/w and in the Lysholm score at a

  10. How constant momentum acceleration decouples energy and space focusing in distance-of-flight and time-of-flight mass spectrometries.

    PubMed

    Dennis, Elise A; Gundlach-Graham, Alexander W; Enke, Christie G; Ray, Steven J; Carado, Anthony J; Barinaga, Charles J; Koppenaal, David W; Hieftje, Gary M

    2013-05-01

    Resolution in time-of-flight mass spectrometry (TOFMS) is ordinarily limited by the initial energy and space distributions within an instrument's acceleration region and by the length of the field-free flight zone. With gaseous ion sources, these distributions lead to systematic flight-time errors that cannot be simultaneously corrected with conventional static-field ion-focusing devices (i.e., an ion mirror). It is known that initial energy and space distributions produce non-linearly correlated errors in both ion velocity and exit time from the acceleration region. Here we reinvestigate an old acceleration technique, constant-momentum acceleration (CMA), to decouple the effects of initial energy and space distributions. In CMA, only initial ion energies (and not their positions) affect the velocity ions gain. Therefore, with CMA, the spatial distribution within the acceleration region can be manipulated without creating ion-velocity error. The velocity differences caused by a spread in initial ion energy can be corrected with an ion mirror. We discuss here the use of CMA and independent focusing of energy and space distributions for both distance-of-flight mass spectrometry (DOFMS) and TOFMS. Performance characteristics of our CMA-DOFMS and CMA-TOFMS instrument, fitted with a glow-discharge ionization source, are described. In CMA-DOFMS, resolving powers (FWHM) of greater than 1000 are achieved for atomic ions with a flight length of 285 mm. In CMA-TOFMS, only ions over a narrow range of m/z values can be energy-focused; however, the technique offers improved resolution for these focused ions, with resolving powers of greater than 2000 for a separation distance of 350 mm.

  11. DC-like Phase Space Manipulation and Particle Acceleration Using Chirped AC Fields

    SciTech Connect

    P.F. Schmit and N.J. Fisch

    2009-06-17

    Waves in plasmas can accelerate particles that are resonant with the wave. A DC electric field also accelerates particles, but without a resonance discrimination, which makes the acceleration mechanism profoundly different. We investigate the effect on a Hamiltonian distribution of an accelerating potential waveform, which could, for example, represent the average ponderomotive effect of two counterpropagating electromagnetic waves. In particular, we examine the apparent DC-like time-asymptotic response of the distribution in regimes where the potential structure is accelerated adiabatically. A highly resonant population within the distribution is always present, and we characterize its nonadiabatic response during wave-particle resonance using an integral method in the noninertial reference frame moving with the wave. Finally, we show that in the limit of infinitely slow acceleration of the wave, these highly resonant particles disappear and the response

  12. Quantitative rotating frame relaxometry methods in MRI.

    PubMed

    Gilani, Irtiza Ali; Sepponen, Raimo

    2016-06-01

    Macromolecular degeneration and biochemical changes in tissue can be quantified using rotating frame relaxometry in MRI. It has been shown in several studies that the rotating frame longitudinal relaxation rate constant (R1ρ ) and the rotating frame transverse relaxation rate constant (R2ρ ) are sensitive biomarkers of phenomena at the cellular level. In this comprehensive review, existing MRI methods for probing the biophysical mechanisms that affect the rotating frame relaxation rates of the tissue (i.e. R1ρ and R2ρ ) are presented. Long acquisition times and high radiofrequency (RF) energy deposition into tissue during the process of spin-locking in rotating frame relaxometry are the major barriers to the establishment of these relaxation contrasts at high magnetic fields. Therefore, clinical applications of R1ρ and R2ρ MRI using on- or off-resonance RF excitation methods remain challenging. Accordingly, this review describes the theoretical and experimental approaches to the design of hard RF pulse cluster- and adiabatic RF pulse-based excitation schemes for accurate and precise measurements of R1ρ and R2ρ . The merits and drawbacks of different MRI acquisition strategies for quantitative relaxation rate measurement in the rotating frame regime are reviewed. In addition, this review summarizes current clinical applications of rotating frame MRI sequences. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Computational studies and optimization of wakefield accelerators

    SciTech Connect

    Tsung, Frank S.; Bruhwiler, David L.; Cary, John R.; Esarey, Eric H.; Mori, Warren B.; Vay, Jean-Luc; Martins, Samuel F.; Katsouleas, Tom; Cormier-Michel, Estelle; Fawley, William M.; Huang, Chengkun; Wang, Xiadong; Cowan, Ben; Decyk, Victor K.; Fonseca, Ricardo A.; Lu, Wei; Messmer, Peter; Mullowney, Paul; Nakamura, Kei; Paul, Kevin; Plateau, Guillaume R.; Schroeder, Carl B.; Silva, Luis O.; Toth, Csaba; Geddes, C.G.R.; Tzoufras, Michael; Antonsen, Tom; Vieira, Jorge; Leemans, Wim P.

    2008-06-16

    Laser- and particle beam-driven plasma wakefield accelerators produce accelerating fields thousands of times higher than radio-frequency accelerators, offering compactness and ultrafast bunches to extend the frontiers of high energy physics and to enable laboratory-scale radiation sources. Large-scale kinetic simulations provide essential understanding of accelerator physics to advance beam performance and stability and show and predict the physics behind recent demonstration of narrow energy spread bunches. Benchmarking between codes is establishing validity of the models used and, by testing new reduced models, is extending the reach of simulations to cover upcoming meter-scale multi-GeV experiments. This includes new models that exploit Lorentz boosted simulation frames to speed calculations. Simulations of experiments showed that recently demonstrated plasma gradient injection of electrons can be used as an injector to increase beam quality by orders of magnitude. Simulations are now also modeling accelerator stages of tens of GeV, staging of modules, and new positron sources to design next-generation experiments and to use in applications in high energy physics and light sources.

  14. One-Shot Measurement of Spin-Lattice Relaxation Times in the Off-Resonance Rotating Frame of Reference with Applications to Breast

    NASA Astrophysics Data System (ADS)

    Fairbanks, Ethan Jefferson

    1994-01-01

    Off-resonance spin locking makes use of the novel relaxation time T_{1rho} ^{rm off}, which may be useful in characterizing breast disease. Knowledge of T _{rm 1rho}^{rm off} is essential for optimization of spin -locking imaging methods. The purpose of this work was to develop an optimal imaging technique for in vivo measurement of T_{rm 1rho}^ {rm off}. Measurement of T _{1rho}^{rm off } using conventional methods requires long exam times which are not suitable for patients. Exam time may be shortened by utilizing a one-shot method developed by Look and Locker, making in vivo measurements possible. The imaging method consisted of a 180^circ inversion pulse followed by a series of small-angle alpha pulses to tip a portion of the longitudinal magnetization into the transverse plane for readout. During each relaxation interval (between alpha pulses), a spin-locking pulse was applied off-resonance to achieve T_ {1rho}^{rm off} relaxation. The value of T_{rm 1rho}^{rm off} was then determined using a three-parameter non-linear least-squares fitting procedure. Values of T_ {1rho}^{rm off} were measured for normal and pathologic breast tissues at several resonant offsets. These measurements revealed that image contrast can be manipulated by altering the resonant offset of the spin-locking pulse. Whereas T _1 relaxation times were nearly identical for normal and cancerous tissues, T_{1 rho}^{rm off} relaxation times differed significantly. These results may be useful in improving image contrast in magnetic resonance imaging.

  15. Nanosecond frame cameras

    SciTech Connect

    Frank, A M; Wilkins, P R

    2001-01-05

    The advent of CCD cameras and computerized data recording has spurred the development of several new cameras and techniques for recording nanosecond images. We have made a side by side comparison of three nanosecond frame cameras, examining them for both performance and operational characteristics. The cameras include; Micro-Channel Plate/CCD, Image Diode/CCD and Image Diode/Film; combinations of gating/data recording. The advantages and disadvantages of each device will be discussed.

  16. Pulsars and Acceleration Sites

    NASA Technical Reports Server (NTRS)

    Harding, Alice

    2008-01-01

    Rotation-powered pulsars are excellent laboratories for the studying particle acceleration as well as fundamental physics of strong gravity, strong magnetic fields and relativity. But even forty years after their discovery, we still do not understand their pulsed emission at any wavelength. I will review both the basic physics of pulsars as well as the latest developments in understanding their high-energy emission. Special and general relativistic effects play important roles in pulsar emission, from inertial frame-dragging near the stellar surface to aberration, time-of-flight and retardation of the magnetic field near the light cylinder. Understanding how these effects determine what we observe at different wavelengths is critical to unraveling the emission physics. Fortunately the Gamma-Ray Large Area Space Telescope (GLAST), with launch in May 2008 will detect many new gamma-ray pulsars and test the predictions of these models with unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 300 GeV.

  17. Extended temperature-accelerated dynamics: Enabling long-time full-scale modeling of large rare-event systems

    SciTech Connect

    Bochenkov, Vladimir; Suetin, Nikolay; Shankar, Sadasivan

    2014-09-07

    A new method, the Extended Temperature-Accelerated Dynamics (XTAD), is introduced for modeling long-timescale evolution of large rare-event systems. The method is based on the Temperature-Accelerated Dynamics approach [M. Sørensen and A. Voter, J. Chem. Phys. 112, 9599 (2000)], but uses full-scale parallel molecular dynamics simulations to probe a potential energy surface of an entire system, combined with the adaptive on-the-fly system decomposition for analyzing the energetics of rare events. The method removes limitations on a feasible system size and enables to handle simultaneous diffusion events, including both large-scale concerted and local transitions. Due to the intrinsically parallel algorithm, XTAD not only allows studies of various diffusion mechanisms in solid state physics, but also opens the avenue for atomistic simulations of a range of technologically relevant processes in material science, such as thin film growth on nano- and microstructured surfaces.

  18. Frame for a firearm

    DOEpatents

    Crandall, David L.; Watson, Richard W.

    2008-03-04

    A firearm frame which is adapted to be disposed in operative relationship as a component part of a firearm, the firearm having disposed in operative relationships each with one or more of the others, a barrel, a receiver, and at least one firing mechanism; wherein the barrel and receiver form operative parts of a movable assembly and the at least one firing mechanism is disposed in a substantially stationary operative relationship therewith; the firearm frame including at least one elongated support structure discrete from the barrel and receiver, the elongated support structure being adapted to directly support the movable assembly in an operative movable relationship therewith; whereby at least one of the barrel and receiver is in direct contact with and movable on the elongated support structure; and, a firing mechanism support structure connected to the at least one elongated support structure, the firing mechanism support structure being adapted to have the firing mechanism connected thereto; the firearm frame also directly supporting the movable assembly and the firing mechanism in corresponding movable and stationary operative relationships each with the other.

  19. The Variational Principle for the Uniform Acceleration and Quasi-Spin in Two Dimensional Space-Time

    NASA Astrophysics Data System (ADS)

    Matsyuk, Roman Ya.

    2008-02-01

    The variational principle and the corresponding differential equation for geodesic circles in two dimensional (pseudo)-Riemannian space are being discovered. The relationship with the physical notion of uniformly accelerated relativistic particle is emphasized. The known form of spin-curvature interaction emerges due to the presence of second order derivatives in the expression for the Lagrange function. The variational equation itself reduces to the unique invariant variational equation of constant Frenet curvature in two dimensional (pseudo)-Euclidean geometry.

  20. BICEP's acceleration

    SciTech Connect

    Contaldi, Carlo R.

    2014-10-01

    The recent Bicep2 [1] detection of, what is claimed to be primordial B-modes, opens up the possibility of constraining not only the energy scale of inflation but also the detailed acceleration history that occurred during inflation. In turn this can be used to determine the shape of the inflaton potential V(φ) for the first time — if a single, scalar inflaton is assumed to be driving the acceleration. We carry out a Monte Carlo exploration of inflationary trajectories given the current data. Using this method we obtain a posterior distribution of possible acceleration profiles ε(N) as a function of e-fold N and derived posterior distributions of the primordial power spectrum P(k) and potential V(φ). We find that the Bicep2 result, in combination with Planck measurements of total intensity Cosmic Microwave Background (CMB) anisotropies, induces a significant feature in the scalar primordial spectrum at scales k∼ 10{sup -3} Mpc {sup -1}. This is in agreement with a previous detection of a suppression in the scalar power [2].

  1. Neutron Energy and Time-of-flight Spectra Behind the Lateral Shield of a High Energy Electron Accelerator Beam Dump, Part II: Monte Carlo Simulations

    SciTech Connect

    Roesler, Stefan

    2002-09-19

    Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators.

  2. Calculation of Neutron Time-of-Flight and Energy Spectra Behind Thick Shielding of an Electron Accelerator and Comparison to Experimental Data

    NASA Astrophysics Data System (ADS)

    Roesler, S.

    2002-05-01

    Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators.

  3. Calculation of Neutron Time-of-Flight and Energy Spectra Behind Thick Shielding of an Electron Accelerator and Comparison to Experimental Data

    SciTech Connect

    Roesler, Stefan

    2002-05-06

    Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators.

  4. Vibration of x-braced portal frames

    NASA Astrophysics Data System (ADS)

    Chang, C. H.; Wang, P. Y.; Lin, Y. W.

    1987-09-01

    Both free and forced vibrations of elastic X-braced portal frames are investigated. Solutions of the Euler-Bernoulli equation for the transverse vibration coupled with the axial vibration are used. The first five natural frequencies, with the angle of inclination, α, of the bracing bars ranging from 15° to 75°, with different slenderness ratios, R, of the columns, and different stiffness of the floor beam and crossing bars, are presented along with two sets of the natural modes of the frames with α = 45°. For the forced vibration, the dynamic responses of the frames with a concentrated horizontal time dependent force acting at a top joint are studied. The responses of the frames with α = 45° are analyzed in detail.

  5. Frames of Reference in the Classroom

    NASA Astrophysics Data System (ADS)

    Grossman, Joshua

    2012-12-01

    The classic film "Frames of Reference"1,2 effectively illustrates concepts involved with inertial and non-inertial reference frames. In it, Donald G. Ivey and Patterson Hume use the cameras perspective to allow the viewer to see motion in reference frames translating with a constant velocity, translating while accelerating, and rotating—all with respect to the Earth frame. The film is a classic for good reason, but today it does have a couple of drawbacks: 1) The film by nature only accommodates passive learning. It does not give students the opportunity to try any of the experiments themselves. 2) The dated style of the 50-year-old film can distract students from the physics content. I present here a simple setup that can recreate many of the movies demonstrations in the classroom. The demonstrations can be used to supplement the movie or in its place, if desired. All of the materials except perhaps the inexpensive web camera should likely be available already in most teaching laboratories. Unlike previously described activities, these experiments do not require travel to another location3 or an involved setup.4,5

  6. Teleportation with a uniformly accelerated partner.

    PubMed

    Alsing, Paul M; Milburn, G J

    2003-10-31

    In this work, we give a description of the process of teleportation between Alice in an inertial frame, and Rob who is in uniform acceleration with respect to Alice. The fidelity of the teleportation is reduced due to Davies-Unruh radiation in Rob's frame. In so far as teleportation is a measure of entanglement, our results suggest that quantum entanglement is degraded in noninertial frames.

  7. Reduction of Effective Acceleration to Microgravity Levels

    NASA Technical Reports Server (NTRS)

    Downey, James P.

    2000-01-01

    accelerates according to the force of gravity as do the experimental fluids within the lab. Hence, the magnitude of the form excited by the laboratory on the experimental solutions within are greatly reduced. When compared with a laboratory on the ground and averaged over time, the fluids in a spaceflight laboratory experience approximately a 10 (sup -6)decrease in acceleration relative to their laboratory reference frame hence the term microgravity.

  8. Transitions in students' epistemic framing along two axes

    NASA Astrophysics Data System (ADS)

    Irving, Paul W.; Martinuk, Mathew Sandy; Sayre, Eleanor C.

    2013-06-01

    We use epistemological framing to interpret participants’ behavior during group problem-solving sessions in an intermediate mechanics course. We are interested in how students frame discussion and in how the groups shift discussion framings. Our analysis includes two framing axes, expansive vs narrow and serious vs silly, which together incorporate and extend prior work on how students frame discussions in physics education research. We present markers for where discussion falls on these axes. We support our conclusions with both microanalytic excerpts of discussion and overall analysis of 75 hours of video-based data. We find that the group spends most of its time in more serious framings, and slightly more than half of its time in more narrow ones. The teaching assistant is the participant who initiates the largest number of frame shifts, and her shifts include bids to all quadrants in the expansive or narrow and serious or silly plane.

  9. The fully non-linear post-Friedmann frame-dragging vector potential: magnitude and time evolution from N-body simulations

    NASA Astrophysics Data System (ADS)

    Thomas, Daniel B.; Bruni, Marco; Wands, David

    2015-09-01

    Newtonian simulations are routinely used to examine the matter dynamics on non-linear scales. However, even on these scales, Newtonian gravity is not a complete description of gravitational effects. A post-Friedmann approach shows that the leading-order correction to Newtonian theory is a vector potential in the metric. This vector potential can be calculated from N-body simulations, requiring a method for extracting the velocity field. Here, we present the full details of our calculation of the post-Friedmann vector potential, using the Delaunay Tessellation Field Estimator code. We include a detailed examination of the robustness of our numerical result, including the effects of box size and mass resolution on the extracted fields. We present the power spectrum of the vector potential and find that the power spectrum of the vector potential is ˜105 times smaller than the power spectrum of the fully non-linear scalar gravitational potential at redshift zero. Comparing our numerical results to perturbative estimates, we find that the fully non-linear result can be more than an order of magnitude larger than the perturbative estimate on small scales. We extend the analysis of the vector potential to multiple redshifts, showing that this ratio persists over a range of scales and redshifts. We also comment on the implications of our results for the validity and interpretation of Newtonian simulations.

  10. Conformal frame dependence of inflation

    SciTech Connect

    Domènech, Guillem; Sasaki, Misao E-mail: misao@yukawa.kyoto-u.ac.jp

    2015-04-01

    Physical equivalence between different conformal frames in scalar-tensor theory of gravity is a known fact. However, assuming that matter minimally couples to the metric of a particular frame, which we call the matter Jordan frame, the matter point of view of the universe may vary from frame to frame. Thus, there is a clear distinction between gravitational sector (curvature and scalar field) and matter sector. In this paper, focusing on a simple power-law inflation model in the Einstein frame, two examples are considered; a super-inflationary and a bouncing universe Jordan frames. Then we consider a spectator curvaton minimally coupled to a Jordan frame, and compute its contribution to the curvature perturbation power spectrum. In these specific examples, we find a blue tilt at short scales for the super-inflationary case, and a blue tilt at large scales for the bouncing case.

  11. Idaho Completion Project’s Accelerated Retrieval Project Overview of the Pit 4 Non-Time Critical Removal Action

    SciTech Connect

    T. L. Clements; R. E. Arbon; B. D. Preussner

    2005-02-01

    This paper presents an overview of the Accelerated Retrieval Project performed by the Idaho Completion Project at the Idaho National Laboratory (INL). Topics include an overall description of the process and methods that will retrieve, characterize, and certify newly generated transuranic (TRU) waste for disposal at the Waste Isolation Pilot Plant (WIPP). The retrieval and characterization of buried TRU waste presents unique challenges. Innovative approaches developed and discussed are: excavation, RCRA waste sampling, visual examination, and deployment of the WIPP Central Characterization Project mobile systems to the INL.

  12. Production of Multi-Terawatt Time-Structured CO{sub 2} Laser Pulses for Ion Acceleration

    SciTech Connect

    Haberberger, Dan; Tochitsky, Sergei; Gong Chao; Joshi, Chan

    2010-11-04

    The UCLA Neptune Laboratory CO{sub 2} laser system has been recently upgraded to produce 3ps multi-terawatt 10{mu}m laser pulses. The laser energy is distributed over several 3 ps pulses separated by 18 ps. These temporally structured pulses are applied for laser driven ion acceleration in an H{sub 2} gas jet at a measured plasma density of 2x10{sup 19} cm{sup -3}. Protons in excess of 20 MeV have been observed in the forward direction and with energy spreads ({Delta}E/E{approx}10%).

  13. A greigite-based magnetostratigraphic time frame for the Late Miocene to Recent DSDP Leg 42B cores from the Black Sea

    NASA Astrophysics Data System (ADS)

    van Baak, Christiaan; Vasiliev, Iuliana; Palcu, Dan; Dekkers, Mark; Krijgsman, Wout

    2016-04-01

    In 1975, during DSDP Leg 42B to the Black Sea, three sites were drilled with a total of 2318 m cored and a recovery of 55%. While to modern scientific standards this may not be very impressive, these sites still represent the longest available records of sedimentation in the basinal part of the Black Sea. The main stratigraphic objectives of DSDP Leg 42B were to 1) obtain a complete Pleistocene litho- and biostratigraphic section and 2) study interactions between the Black Sea and Mediterranean Sea, focusing on glacio-eustatic sea level change, periods of lacustrine sedimentation, periods of anoxia, and 3) to establish a paleoclimatic record. Major problems establishing a timescale emerged after drilling due to a) the general shortage of definitive paleontological age markers and b) the general lack of agreement on correlation and time zonation of sedimentary units. Magnetostratigraphic dating could have solved these timescale problems but was hindered by the presence of the little understood authigenic iron sulphide mineral greigite (Fe3S4) as main magnetic carrier. In recent years, the understanding of greigite has significantly improved and is considered a reliable magnetic carrier. Especially in the circum-Black Sea region, many Miocene to recent, land-based sections are magnetostratigraphically dated with greigite as magnetic carrier. We therefore resampled the cores of DSDP Leg 42B to see whether after 40 years of storage any of the original signal is preserved. Our results show these cores are still surprisingly useful for magnetostratigraphic dating. Complications arise due to the presence of hiatuses, especially in the near-Bosporus locations. Our age model gives important new insights into the response of the Black Sea to major paleoenvironmental and climatic changes related to the late Miocene Messinian salinity crisis and throughout the Pleistocene. More generally, our results show that for future deep-sea drilling expeditions to the Black Sea, the

  14. Greigite-based magnetostratigraphic framework for the Late Miocene to recent DSDP Leg 42B cores from the Black Sea: A new time frame for old cores

    NASA Astrophysics Data System (ADS)

    Baak, C. V.; Vasiliev, I.; Grothe, A.; Kuiper, K.; Raffi, I.; Krijgsman, W.

    2014-12-01

    In 1975, DSDP Leg 42B to the Black Sea, three sites were drilled with a total of 2318 m cored and a recovery of 55%. While to modern standards this may not be very impressive, these sites still represent the best record of sedimentation in the basinal part of the Black Sea. The main stratigraphic objectives of DSDP Leg 42B were to 1) obtain a complete Pleistocene litho- and biostratigraphic section and 2) study interactions between the Black Sea and Mediterranean Sea, focusing on glacio-eustatic sea level change, periods of lacustrine sedimentation, periods of stagnation, and to establish a paleoclimatic record. Major problems establishing a timescale emerged after drilling due to a) the general shortage of definitive paleontological age markers and b) the general lack of agreement on correlation and time zonation of sedimentary units. Magnetostratigraphic dating could have solved these timescale problems but was hindered by the presence of the little understood authigenic iron sulphide mineral greigite (Fe3S4) as main magnetic carrier. In recent years, the understanding of greigite has significantly improved and is considered a reliable magnetic carrier. Especially in the circum-Black Sea region, many Miocene to recent, land-based sections are magnetostratigraphically dated with greigite as magnetic carrier. We therefore resample the cores of DSDP Leg 42B to see whether after 40 years of storage any of the original signal is preserved. Our results show these cores are surprisingly useful for magnetostratigraphic dating. We create an integrated bio-magnetostratigraphic framework for the sites of Leg 42B, focusing on the Latest Miocene and Plio-Pleistocene. Ar/Ar dating of an ash-layer at site 380A gives additional age constraints. Our age model gives important new insights into the response of the Black Sea to major paleoenvironmental and climatic changes like e.g. the Messinian salinity crisis, the mid-Pliocene warm period and Pleistocene glaciations on the

  15. A novel adaptive time stepping variant of the Boris–Buneman integrator for the simulation of particle accelerators with space charge

    SciTech Connect

    Toggweiler, Matthias; Adelmann, Andreas; Arbenz, Peter; Yang, Jianjun

    2014-09-15

    We show that adaptive time stepping in particle accelerator simulation is an enhancement for certain problems. The new algorithm has been implemented in the OPAL (Object Oriented Parallel Accelerator Library) framework. The idea is to adjust the frequency of costly self-field calculations, which are needed to model Coulomb interaction (space charge) effects. In analogy to a Kepler orbit simulation that requires a higher time step resolution at the close encounter, we propose to choose the time step based on the magnitude of the space charge forces. Inspired by geometric integration techniques, our algorithm chooses the time step proportional to a function of the current phase space state instead of calculating a local error estimate like a conventional adaptive procedure. Building on recent work, a more profound argument is given on how exactly the time step should be chosen. An intermediate algorithm, initially built to allow a clearer analysis by introducing separate time steps for external field and self-field integration, turned out to be useful by its own, for a large class of problems.

  16. VIOLENT FRAMES IN ACTION

    SciTech Connect

    Sanfilippo, Antonio P.; McGrath, Liam R.; Whitney, Paul D.

    2011-11-17

    We present a computational approach to radical rhetoric that leverages the co-expression of rhetoric and action features in discourse to identify violent intent. The approach combines text mining and machine learning techniques with insights from Frame Analysis and theories that explain the emergence of violence in terms of moral disengagement, the violation of sacred values and social isolation in order to build computational models that identify messages from terrorist sources and estimate their proximity to an attack. We discuss a specific application of this approach to a body of documents from and about radical and terrorist groups in the Middle East and present the results achieved.

  17. The Levels of Visual Framing

    ERIC Educational Resources Information Center

    Rodriguez, Lulu; Dimitrova, Daniela V.

    2011-01-01

    While framing research has centered mostly on the evaluations of media texts, visual news discourse has remained relatively unexamined. This study surveys the visual framing techniques and methods employed in previous studies and proposes a four-tiered model of identifying and analyzing visual frames: (1) visuals as denotative systems, (2) visuals…

  18. Fiber Accelerating Structures

    SciTech Connect

    Hammond, Andrew P.; /Reed Coll. /SLAC

    2010-08-25

    One of the options for future particle accelerators are photonic band gap (PBG) fiber accelerators. PBG fibers are specially designed optical fibers that use lasers to excite an electric field that is used to accelerate electrons. To improve PBG accelerators, the basic parameters of the fiber were tested to maximize defect size and acceleration. Using the program CUDOS, several accelerating modes were found that maximized these parameters for several wavelengths. The design of multiple defects, similar to having closely bound fibers, was studied to find possible coupling or the change of modes. The amount of coupling was found to be dependent on distance separated. For certain distances accelerating coupled modes were found and examined. In addition, several non-periodic fiber structures were examined using CUDOS. The non-periodic fibers produced several interesting results and promised more modes given time to study them in more detail.

  19. On the role of local CIR-associated particle acceleration in formation of time-intensity profiles of suprathermal particle fluxes

    NASA Astrophysics Data System (ADS)

    Khabarova, Olga; Malandraki, Olga E.

    2015-04-01

    A possibility of local acceleration of particles up to several MeV at the edge of corotating interaction regions (CIRs) in the solar wind is discussed. Recently, evidence for significant local particle energization due to magnetic reconnection that occurs at the heliospheric current sheet (HCS) and followed by consequent trapping and re-acceleration of suprathermal particles in magnetic islands surrounding the rippled HCS was provided (Khabarova et al. 2014). We investigate this phenomenon in application to particle energization at current sheets of various scales (from the HCS to local small-scale current sheets), including current sheets frequently observed at the edge of CIRs, and explore the role of magnetic islands in the picture of suprathermal particle flux enhancements associated with CIRs. It is commonly believed that CIRs serve as one of the sources of suprathermal particles at the Earth's orbit in addition to flares and pre-CME shocks because of particle acceleration by reverse shocks formed beyond 2-3AU. However, this paradigm demands a free way of particles back from the shocks to 1 AU, which produces specific timing and ion/electron flux features that are not observed every time. We suggest that local particle acceleration may take place directly at the CIR edge in the case of the HCS-CIR interaction, as well as be determined by the occurrence of electric field in merging/contracting magnetic islands and local reconnecting current sheets (Zank et al. 2014) in the turbulent plasma of CIRs. Multi-spacecraft data analysis (STEREO, Wind, ACE and Ulysses) is performed. Khabarova O., Zank G.P., Li G., le Roux J.A., Webb G.M., Dosch A., Zharkova V.V. and Malandraki O.E., Small-scale magnetic islands in the solar wind and their role in particle acceleration. Part 1: Dynamics of magnetic islands near the heliospheric current sheet. Submitted to ApJ, 2014 Zank G.P., le Roux J.A., Webb G.M., Dosch A., and O. Khabarova. Particle acceleration via reconnection

  20. Inertial nonvacuum states viewed from the Rindler frame

    NASA Astrophysics Data System (ADS)

    Lochan, Kinjalk; Padmanabhan, T.

    2015-02-01

    The appearance of the inertial vacuum state in Rindler frame has been extensively studied in the literature, both from the point of view of quantum field theory developed using Rindler foliation and using the response of an Unruh-Dewitt detector. In comparison, less attention has been devoted to the study of inertial nonvacuum states when viewed from the Rindler frame. We provide a comprehensive study of this issue in this paper. We first present a general formalism describing the characterization of arbitrary inertial state (i) when described using an arbitrary foliation and (ii) using the response of an Unruh-DeWitt detector moving along an arbitrary trajectory. This allows us to calculate the mean number of particles in an arbitrary inertial state, when the QFT is described using an arbitrary foliation of spacetime or when the state is probed by a detector moving along an arbitrary trajectory. We use this formalism to explicitly compute the results for the Rindler frame and uniformly accelerated detectors. Any arbitrary inertial state will always have a thermal component in the Rindler frame with additional contributions arising from the nonvacuum nature. We classify the nature of the additional contributions in terms of functions characterizing the inertial state. We establish that for all physically well-behaved normalizable inertial states, the correction terms decrease rapidly with the energy of the Rindler mode so that the high frequency limit is dominated by the thermal noise in any normalizable inertial state. However, inertial states which are not strictly normalizable like, for example, the one-particle state with definite momentum, lead to a constant contribution at all high frequencies in the Rindler frame. We show that a similar behavior arises in the response of the Unruh-DeWitt detector as well. In the case of the detector response, we provide a physical interpretation for the constant contribution at high frequencies in terms of total detection

  1. Particle acceleration in flares

    NASA Technical Reports Server (NTRS)

    Benz, Arnold O.; Kosugi, Takeo; Aschwanden, Markus J.; Benka, Steve G.; Chupp, Edward L.; Enome, Shinzo; Garcia, Howard; Holman, Gordon D.; Kurt, Victoria G.; Sakao, Taro

    1994-01-01

    Particle acceleration is intrinsic to the primary energy release in the impulsive phase of solar flares, and we cannot understand flares without understanding acceleration. New observations in soft and hard X-rays, gamma-rays and coherent radio emissions are presented, suggesting flare fragmentation in time and space. X-ray and radio measurements exhibit at least five different time scales in flares. In addition, some new observations of delayed acceleration signatures are also presented. The theory of acceleration by parallel electric fields is used to model the spectral shape and evolution of hard X-rays. The possibility of the appearance of double layers is further investigated.

  2. Cognitive framing in action.

    PubMed

    Huhn, John M; Potts, Cory Adam; Rosenbaum, David A

    2016-06-01

    Cognitive framing effects have been widely reported in higher-level decision-making and have been ascribed to rules of thumb for quick thinking. No such demonstrations have been reported for physical action, as far as we know, but they would be expected if cognition for physical action is fundamentally similar to cognition for higher-level decision-making. To test for such effects, we asked participants to reach for a horizontally-oriented pipe to move it from one height to another while turning the pipe 180° to bring one end (the "business end") to a target on the left or right. From a physical perspective, participants could have always rotated the pipe in the same angular direction no matter which end was the business end; a given participant could have always turned the pipe clockwise or counter-clockwise. Instead, our participants turned the business end counter-clockwise for left targets and clockwise for right targets. Thus, the way the identical physical task was framed altered the way it was performed. This finding is consistent with the hypothesis that cognition for physical action is fundamentally similar to cognition for higher-level decision-making. A tantalizing possibility is that higher-level decision heuristics have roots in the control of physical action, a hypothesis that accords with embodied views of cognition. PMID:26970853

  3. High Performance Commercial Fenestration Framing Systems

    SciTech Connect

    Mike Manteghi; Sneh Kumar; Joshua Early; Bhaskar Adusumalli

    2010-01-31

    A major objective of the U.S. Department of Energy is to have a zero energy commercial building by the year 2025. Windows have a major influence on the energy performance of the building envelope as they control over 55% of building energy load, and represent one important area where technologies can be developed to save energy. Aluminum framing systems are used in over 80% of commercial fenestration products (i.e. windows, curtain walls, store fronts, etc.). Aluminum framing systems are often required in commercial buildings because of their inherent good structural properties and long service life, which is required from commercial and architectural frames. At the same time, they are lightweight and durable, requiring very little maintenance, and offer design flexibility. An additional benefit of aluminum framing systems is their relatively low cost and easy manufacturability. Aluminum, being an easily recyclable material, also offers sustainable features. However, from energy efficiency point of view, aluminum frames have lower thermal performance due to the very high thermal conductivity of aluminum. Fenestration systems constructed of aluminum alloys therefore have lower performance in terms of being effective barrier to energy transfer (heat loss or gain). Despite the lower energy performance, aluminum is the choice material for commercial framing systems and dominates the commercial/architectural fenestration market because of the reasons mentioned above. In addition, there is no other cost effective and energy efficient replacement material available to take place of aluminum in the commercial/architectural market. Hence it is imperative to improve the performance of aluminum framing system to improve the energy performance of commercial fenestration system and in turn reduce the energy consumption of commercial building and achieve zero energy building by 2025. The objective of this project was to develop high performance, energy efficient commercial

  4. Frame architecture for video servers

    NASA Astrophysics Data System (ADS)

    Venkatramani, Chitra; Kienzle, Martin G.

    1999-11-01

    Video is inherently frame-oriented and most applications such as commercial video processing require to manipulate video in terms of frames. However, typical video servers treat videos as byte streams and perform random access based on approximate byte offsets to be supplied by the client. They do not provide frame or timecode oriented API which is essential for many applications. This paper describes a frame-oriented architecture for video servers. It also describes the implementation in the context of IBM's VideoCharger server. The later part of the paper describes an application that uses the frame architecture and provides fast and slow-motion scanning capabilities to the server.

  5. Clover root exudate produces male-biased sex ratios and accelerates male metamorphic timing in wood frogs.

    PubMed

    Lambert, Max R

    2015-12-01

    In amphibians, abnormal metamorph sex ratios and sexual development have almost exclusively been considered in response to synthetic compounds like pesticides or pharmaceuticals. However, endocrine-active plant chemicals (i.e. phytoestrogens) are commonly found in agricultural and urban waterways hosting frog populations with deviant sexual development. Yet the effects of these compounds on amphibian development remain predominantly unexplored. Legumes, like clover, are common in agricultural fields and urban yards and exude phytoestrogen mixtures from their roots. These root exudates serve important ecological functions and may also be a source of phytoestrogens in waterways. I show that clover root exudate produces male-biased sex ratios and accelerates male metamorphosis relative to females in low and intermediate doses of root exudate. My results indicate that root exudates are a potential source of contaminants impacting vertebrate development and that humans may be cultivating sexual abnormalities in wildlife by actively managing certain plant species.

  6. Clover root exudate produces male-biased sex ratios and accelerates male metamorphic timing in wood frogs.

    PubMed

    Lambert, Max R

    2015-12-01

    In amphibians, abnormal metamorph sex ratios and sexual development have almost exclusively been considered in response to synthetic compounds like pesticides or pharmaceuticals. However, endocrine-active plant chemicals (i.e. phytoestrogens) are commonly found in agricultural and urban waterways hosting frog populations with deviant sexual development. Yet the effects of these compounds on amphibian development remain predominantly unexplored. Legumes, like clover, are common in agricultural fields and urban yards and exude phytoestrogen mixtures from their roots. These root exudates serve important ecological functions and may also be a source of phytoestrogens in waterways. I show that clover root exudate produces male-biased sex ratios and accelerates male metamorphosis relative to females in low and intermediate doses of root exudate. My results indicate that root exudates are a potential source of contaminants impacting vertebrate development and that humans may be cultivating sexual abnormalities in wildlife by actively managing certain plant species. PMID:27019728

  7. Clover root exudate produces male-biased sex ratios and accelerates male metamorphic timing in wood frogs

    PubMed Central

    Lambert, Max R.

    2015-01-01

    In amphibians, abnormal metamorph sex ratios and sexual development have almost exclusively been considered in response to synthetic compounds like pesticides or pharmaceuticals. However, endocrine-active plant chemicals (i.e. phytoestrogens) are commonly found in agricultural and urban waterways hosting frog populations with deviant sexual development. Yet the effects of these compounds on amphibian development remain predominantly unexplored. Legumes, like clover, are common in agricultural fields and urban yards and exude phytoestrogen mixtures from their roots. These root exudates serve important ecological functions and may also be a source of phytoestrogens in waterways. I show that clover root exudate produces male-biased sex ratios and accelerates male metamorphosis relative to females in low and intermediate doses of root exudate. My results indicate that root exudates are a potential source of contaminants impacting vertebrate development and that humans may be cultivating sexual abnormalities in wildlife by actively managing certain plant species. PMID:27019728

  8. Intelligence's likelihood and evolutionary time frame

    NASA Astrophysics Data System (ADS)

    Bogonovich, Marc

    2011-04-01

    This paper outlines hypotheses relevant to the evolution of intelligent life and encephalization in the Phanerozoic. If general principles are inferable from patterns of Earth life, implications could be drawn for astrobiology. Many of the outlined hypotheses, relevant data, and associated evolutionary and ecological theory are not frequently cited in astrobiological journals. Thus opportunity exists to evaluate reviewed hypotheses with an astrobiological perspective. A quantitative method is presented for testing one of the reviewed hypotheses (hypothesis i; the diffusion hypothesis). Questions are presented throughout, which illustrate that the question of intelligent life's likelihood can be expressed as multiple, broadly ranging, more tractable questions.

  9. Time development of high-altitude auroral acceleration region plasma, potentials, and field-aligned current systems observed by Cluster during a substorm

    NASA Astrophysics Data System (ADS)

    Hull, A. J.; Chaston, C. C.; Fillingim, M. O.; Mozer, F.; Frey, H. U.

    2013-12-01

    The auroral acceleration region is an integral link in the chain of events that transpire during substorms, and the currents, plasma and electric fields undergo significant changes driven by complex dynamical processes deep in the magnetotail. These auroral acceleration processes in turn accelerate and heat the plasma that ultimately leads to some of the most intense global substorm auroral displays. The complex interplay between field-aligned current system formation, the development of parallel electric fields, and resultant changes in the plasma constituents that occur during substorms within or just above the auroral acceleration zone remain unclear. We present Cluster multi-point observations within the high-altitude acceleration region (> 3 Re altitude) at key instances during the development of a substorm. Of particular emphasis is on the time-development of the plasma, potentials and currents that occur therein with the aim of ascertaining high-altitude drivers of substorm active auroral acceleration processes and auroral emission consequences. Preliminary results show that the initial onset is dominated by Alfvenic activity as evidenced by the sudden occurrence of relatively intense, short-spatial scale Alfvenic currents and attendant energy dispersed, counterstreaming electrons poleward of the growth-phase arc. The Alfvenic currents are locally planar structures with characteristic thicknesses on the order of a few tens of kilometers. In subsequent passages by the other spacecraft, the plasma sheet region became hotter and thicker via the injection of new hot, dense plasma of magnetospheric origins poleward of the pre-existing growth phase arc. In association with the heating and/or thickening of the plasma sheet, the currents appeared to broaden to larger scales as Alfven dominated activity gave way to either inverted-V dominated or mixed inverted-V and Alfvenic behavior depending on location. The transition from Alfven dominated to inverted-V dominated

  10. Future accelerators (?)

    SciTech Connect

    John Womersley

    2003-08-21

    I describe the future accelerator facilities that are currently foreseen for electroweak scale physics, neutrino physics, and nuclear structure. I will explore the physics justification for these machines, and suggest how the case for future accelerators can be made.

  11. Semiclassical framed BPS states

    NASA Astrophysics Data System (ADS)

    Moore, Gregory W.; Royston, Andrew B.; Van den Bleeken, Dieter

    2016-07-01

    We provide a semiclassical description of framed BPS states in four-dimensional {N}=2 super Yang-Mills theories probed by 't Hooft defects, in terms of a supersymmetric quantum mechanics on the moduli space of singular monopoles. Framed BPS states, like their ordinary counterparts in the theory without defects, are associated with the L 2 kernel of certain Dirac operators on moduli space, or equivalently with the L 2 cohomology of related Dolbeault operators. The Dirac/Dolbeault operators depend on two Cartan-valued Higgs vevs. We conjecture a map between these vevs and the Seiberg-Witten special coordinates, consistent with a one-loop analysis and checked in examples. The map incorporates all perturbative and nonperturbative corrections that are relevant for the semiclassical construction of BPS states, over a suitably defined weak coupling regime of the Coulomb branch. We use this map to translate wall crossing formulae and the no-exotics theorem to statements about the Dirac/Dolbeault operators. The no-exotics theorem, concerning the absence of nontrivial SU(2) R representations in the BPS spectrum, implies that the kernel of the Dirac operator is chiral, and further translates into a statement that all L 2 cohomology of the Dolbeault operator is concentrated in the middle degree. Wall crossing formulae lead to detailed predictions for where the Dirac operators fail to be Fredholm and how their kernels jump. We explore these predictions in nontrivial examples. This paper explains the background and arguments behind the results announced in the short note [1].

  12. Optimization of a space spectrograph main frame and frequency response analysis of the frame

    NASA Astrophysics Data System (ADS)

    Zhang, Xin-yu; Chen, Zhi-yuan; Yang, Shi-mo

    2009-07-01

    A space spectrograph main structure is optimized and examined in order to satisfy the space operational needs. The space spectrograph will be transported into its operational orbit by the launch vehicle and it will undergo dynamic environment in the spacecraft injection period. The unexpected shocks may cause declination of observation accuracy and even equipment damages. The main frame is one of the most important parts because its mechanical performance has great influence on the operational life of the spectrograph, accuracy of observation, etc. For the reason of cost reduction and stability confirming, lower weight and higher structure stiffness of the frame are simultaneously required. Structure optimization was conducted considering the initial design modal analysis results. The base modal frequency raised 10.34% while the whole weight lowered 8.63% compared to the initial design. The purpose of this study is to analyze the new design of main frame mechanical properties and verify whether it can satisfy strict optical demands under the dynamic impact during spacecraft injection. For realizing and forecasting the frequency response characteristics of the main structure in mechanical environment experiment, dynamic analysis of the structure should be performed simulating impulse loads from the bottom base. Therefore, frequency response analysis (FRA) of the frame was then performed using the FEA software MSC.PATRAN/NASTRAN. Results of shock response spectrum (SRS) responses from the base excitations were given. Stress and acceleration dynamic responses of essential positions in the spacecraft injection course were also calculated and spectrometer structure design was examined considering stiffness / strength demands. In this simulation, maximum stresses of Cesic material in two acceleration application cases are 45.1 and 74.1 MPa, respectively. They are all less than yield strengths. As is demonstrated from the simulation, strength reservation of the frame is

  13. Transformation Theory, Accelerating Frames, and Two Simple Problems

    ERIC Educational Resources Information Center

    Schmid, G. Bruno

    1977-01-01

    Presents an operator which transforms quantum functions to solve problems of the stationary state wave functions for a particle and the motion and spreading of a Gaussian wave packet in uniform gravitational fields. (SL)

  14. Analysis of dynamic testing performed on structural clay tile infilled frames

    SciTech Connect

    Fowler, J.J.

    1994-12-18

    The behavior of two structural clay tile infilled frames subjected to dynamic loading is investigated. The testing was performed by USACERL using a biaxial shake table machine on which two framed infills were spaced nine feet apart and connected by steel trusses and an eight inch concrete roof slab. The infills were composed of structural clay tile block which were laid with the cores horizontal. The specimen was loaded in both the out-of-plane and in-plane directions using a site specific time history record. The testing focused on determining frame and panel load-deflection behavior, acceleration amplification, and frequency degradation characteristics. The out-of-plane tests resulted in little degradation of frequency which means there was little loss of stiffness. There was no evidence of the infill {open_quotes}walking-out{close_quotes} of the steel frame; in fact the infill still had substantial stability after completion of the out-of-plane tests. As a result of the gradual increase in ground motion in the in-plane testing, the stiffness of the specimen gradually decreased. Strength and stiffness characteristics obtained from the dynamic testing were comparable to results and behavior seen in static tests. Degradation in the panel was much more rapid under the stronger ground motions which were produced during the sine sweep tests.

  15. Uniform acceleration in general relativity

    NASA Astrophysics Data System (ADS)

    Friedman, Yaakov; Scarr, Tzvi

    2015-10-01

    We extend de la Fuente and Romero's (Gen Relativ Gravit 47:33, 2015) defining equation for uniform acceleration in a general curved spacetime from linear acceleration to the full Lorentz covariant uniform acceleration. In a flat spacetime background, we have explicit solutions. We use generalized Fermi-Walker transport to parallel transport the Frenet basis along the trajectory. In flat spacetime, we obtain velocity and acceleration transformations from a uniformly accelerated system to an inertial system. We obtain the time dilation between accelerated clocks. We apply our acceleration transformations to the motion of a charged particle in a constant electromagnetic field and recover the Lorentz-Abraham-Dirac equation.

  16. Clinical performance of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast-enhanced pediatric abdominal MR angiography

    PubMed Central

    Yousaf, Ufra; Hsiao, Albert; Cheng, Joseph Y.; Alley, Marcus T.; Lustig, Michael; Pauly, John M.; Vasanawala, Shreyas S.

    2015-01-01

    Background Pediatric contrast-enhanced MR angiography is often limited by respiration, other patient motion and compromised spatiotemporal resolution. Objective To determine the reliability of a free-breathing spatiotemporally accelerated 3-D time-resolved contrast enhanced MR angiography method for depicting abdominal arterial anatomy in young children. Materials and methods With IRB approval and informed consent, we retrospectively identified 27 consecutive children (16 males and 11 females; mean age: 3.8 years, range: 14 days to 8.4 years) referred for contrast enhanced MR angiography at our institution, who had undergone free-breathing spatiotemporally accelerated time-resolved contrast enhanced MR angiography studies. An radio-frequency-spoiled gradient echo sequence with Cartesian variable density k-space sampling and radial view ordering, intrinsic motion navigation and intermittent fat suppression was developed. Images were reconstructed with soft-gated parallel imaging locally low-rank method to achieve both motion correction and high spatiotemporal resolution. Quality of delineation of 13 abdominal arteries in the reconstructed images was assessed independently by two radiologists on a five-point scale. Ninety-five percent confidence intervals of the proportion of diagnostically adequate cases were calculated. Interobserver agreements were also analyzed. Results Eleven out of 13 arteries achieved acceptable image quality (mean score range: 3.9–5.0) for both readers. Fair to substantial interobserver agreement was reached on nine arteries. Conclusion Free-breathing spatiotemporally accelerated 3-D time-resolved contrast enhanced MR angiography frequently yields diagnostic image quality for most abdominal arteries for pediatric contrast enhanced MR angiography. PMID:26040509

  17. Real-time GPU-accelerated processing and volumetric display for wide-field laser-scanning optical-resolution photoacoustic microscopy

    PubMed Central

    Kang, Heesung; Lee, Sang-Won; Lee, Eun-Soo; Kim, Se-Hwa; Lee, Tae Geol

    2015-01-01

    Fast signal processing and real-time displays are essential for practical imaging modality in various fields of applications. However, the imaging speed in optical-resolution photoacoustic microscopy (OR-PAM), in particular, depends on factors such as the pulse repetition rate of the laser, scanning method, field of view (FOV), and signal processing time. In the past, efforts to increase acquisition speed either focused on developing new scanning methods or using lasers with higher pulse repetition rates. However, high-speed signal processing is also important for real-time volumetric display in OR-PAM. In this study, we carried out parallel signal processing using a graphics processing unit (GPU) to enable fast signal processing and wide-field real-time displays in laser-scanning OR-PAM. The average total GPU processing time for a B-mode PAM image was approximately 1.35 ms at a display speed of 480 fps when the data samples were acquired with 736 (axial) × 500 (lateral) points/B-mode-frame at a pulse repetition rate of 300 kHz. In addition, we successfully displayed maximum amplitude projection images of a mouse’s ear as volumetric images with an FOV of 3 mm × 3 mm (500 × 500 pixels) at 1.02 s, corresponding to 0.98 fps. PMID:26713184

  18. Straight Metalworking Fluids and All-Cause and Cardiovascular Mortality Analyzed by Using G-Estimation of an Accelerated Failure Time Model With Quantitative Exposure: Methods and Interpretations.

    PubMed

    Picciotto, Sally; Ljungman, Petter L; Eisen, Ellen A

    2016-04-01

    Straight metalworking fluids have been linked to cardiovascular mortality in analyses using binary exposure metrics, accounting for healthy worker survivor bias by using g-estimation of accelerated failure time models. A cohort of 38,666 Michigan autoworkers was followed (1941-1994) for mortality from all causes and ischemic heart disease. The structural model chosen here, using continuous exposure, assumes that increasing exposure from 0 to 1 mg/m(3) in any single year would decrease survival time by a fixed amount. Under that assumption, banning the fluids would have saved an estimated total of 8,468 (slope-based 95% confidence interval: 2,262, 28,563) person-years of life in this cohort. On average, 3.04 (slope-based 95% confidence interval: 0.02, 25.98) years of life could have been saved for each exposed worker who died from ischemic heart disease. Estimates were sensitive to both model specification for predicting exposure (multinomial or logistic regression) and characterization of exposure as binary or continuous in the structural model. Our results provide evidence supporting the hypothesis of a detrimental relationship between straight metalworking fluids and mortality, particularly from ischemic heart disease, as well as an instructive example of the challenges in obtaining and interpreting results from accelerated failure time models using a continuous exposure in the presence of competing risks. PMID:26968943

  19. Microscale acceleration history discriminators

    DOEpatents

    Polosky, Marc A.; Plummer, David W.

    2002-01-01

    A new class of micromechanical acceleration history discriminators is claimed. These discriminators allow the precise differentiation of a wide range of acceleration-time histories, thereby allowing adaptive events to be triggered in response to the severity (or lack thereof) of an external environment. Such devices have applications in airbag activation, and other safety and surety applications.

  20. The Dielectric Wall Accelerator

    SciTech Connect

    Caporaso, George J.; Chen, Yu-Jiuan; Sampayan, Stephen E.

    2009-01-01

    The Dielectric Wall Accelerator (DWA), a class of induction accelerators, employs a novel insulating beam tube to impress a longitudinal electric field on a bunch of charged particles. The surface flashover characteristics of this tube may permit the attainment of accelerating gradients on the order of 100 MV/m for accelerating pulses on the order of a nanosecond in duration. A virtual traveling wave of excitation along the tube is produced at any desired speed by controlling the timing of pulse generating modules that supply a tangential electric field to the tube wall. Because of the ability to control the speed of this virtual wave, the accelerator is capable of handling any charge to mass ratio particle; hence it can be used for electrons, protons and any ion. The accelerator architectures, key technologies and development challenges will be described.

  1. Switched matrix accelerator

    SciTech Connect

    Whittum, David H.; Tantawi, Sami G.

    2001-01-01

    We describe a new concept for a microwave circuit functioning as a charged-particle accelerator at mm wavelengths, permitting an accelerating gradient higher than conventional passive circuits can withstand consistent with cyclic fatigue. The device provides acceleration for multiple bunches in parallel channels, and permits a short exposure time for the conducting surface of the accelerating cavities. Our analysis includes scalings based on a smooth transmission line model and a complementary treatment with a coupled-cavity simulation. We also provide an electromagnetic design for the accelerating structure, arriving at rough dimensions for a seven-cell accelerator matched to standard waveguide and suitable for bench tests at low power in air at 91.392 GHz. A critical element in the concept is a fast mm-wave switch suitable for operation at high power, and we present the considerations for implementation in an H-plane tee. We discuss the use of diamond as the photoconductor switch medium.

  2. Switched Matrix Accelerator

    SciTech Connect

    Whittum, David H

    2000-10-04

    We describe a new concept for a microwave circuit functioning as a charged-particle accelerator at mm-wavelengths, permitting an accelerating gradient higher than conventional passive circuits can withstand consistent with cyclic fatigue. The device provides acceleration for multiple bunches in parallel channels, and permits a short exposure time for the conducting surface of the accelerating cavities. Our analysis includes scalings based on a smooth transmission line model and a complementary treatment with a coupled-cavity simulation. We provide also an electromagnetic design for the accelerating structure, arriving at rough dimensions for a seven-cell accelerator matched to standard waveguide and suitable for bench tests at low power in air at 91.392. GHz. A critical element in the concept is a fast mm-wave switch suitable for operation at high-power, and we present the considerations for implementation in an H-plane tee. We discuss the use of diamond as the photoconductor switch medium.

  3. Microelectromechanical acceleration-sensing apparatus

    DOEpatents

    Lee, Robb M.; Shul, Randy J.; Polosky, Marc A.; Hoke, Darren A.; Vernon, George E.

    2006-12-12

    An acceleration-sensing apparatus is disclosed which includes a moveable shuttle (i.e. a suspended mass) and a latch for capturing and holding the shuttle when an acceleration event is sensed above a predetermined threshold level. The acceleration-sensing apparatus provides a switch closure upon sensing the acceleration event and remains latched in place thereafter. Examples of the acceleration-sensing apparatus are provided which are responsive to an acceleration component in a single direction (i.e. a single-sided device) or to two oppositely-directed acceleration components (i.e. a dual-sided device). A two-stage acceleration-sensing apparatus is also disclosed which can sense two acceleration events separated in time. The acceleration-sensing apparatus of the present invention has applications, for example, in an automotive airbag deployment system.

  4. Virtual Frame Buffer Interface Program

    NASA Technical Reports Server (NTRS)

    Wolfe, Thomas L.

    1990-01-01

    Virtual Frame Buffer Interface program makes all frame buffers appear as generic frame buffer with specified set of characteristics, allowing programmers to write codes that run unmodified on all supported hardware. Converts generic commands to actual device commands. Consists of definition of capabilities and FORTRAN subroutines called by application programs. Developed in FORTRAN 77 for DEC VAX 11/780 or DEC VAX 11/750 computer under VMS 4.X.

  5. The Effects of Acceleration Noise Performance on the Determination of the Earth's Time-varying Gravity Field for Low-low satellite-to-satellite Tracking missions.

    NASA Astrophysics Data System (ADS)

    Hong, S. H.; Conklin, J. W.

    2015-12-01

    GRACE provides monthly average gravity field solutions in spherical harmonic coefficients, which gives us information about land and ocean mass variations with a spatial resolution of 1 degree and with an accuracy within 2 cm throughout the entire Earth. GRACE-FO is expected to be launched in 2017 to continue the work of GRACE and to test a new laser ranging interferometer (LRI) which measures the range between the two satellites with higher precision than the K-Band ranging system used in GRACE. Moreover, there have been simulation studies that show that an additional pair of satellites in an inclined orbit increases the sampling frequency and reduces temporal aliasing errors. On the other hand, GOCE used an electrostatic gravity gradiometer and a drag-free control system to compensate for the non-gravitational forces which had better performance than the electrostatic accelerometers of GRACE. Given the fact that future missions will likely continue to use the low-low satellite-to-satellite tracking formation with LRI onboard, it is expected that acceleration noise caused by non-gravitational forces will become a limiting factor for the time-varying gravity field solution. This research evaluates the effects of acceleration noise on the estimation of the time-varying gravity field for a single pair and the optimal double pairs of satellites, assuming that the satellites fly in collinear pairs with LRI. Spherical harmonic coefficients are used to represent the solution and a batch computation Kalman filter is used to estimate the solutions. Various levels of residual noise for existing drag-free systems are applied as acceleration noise to find suitable drag-free performance requirements for upcoming geodesy missions.

  6. Real time mitigation of atmospheric turbulence in long distance imaging using the lucky region fusion algorithm with FPGA and GPU hardware acceleration

    NASA Astrophysics Data System (ADS)

    Jackson, Christopher Robert

    "Lucky-region" fusion (LRF) is a synthetic imaging technique that has proven successful in enhancing the quality of images distorted by atmospheric turbulence. The LRF algorithm selects sharp regions of an image obtained from a series of short exposure frames, and fuses the sharp regions into a final, improved image. In previous research, the LRF algorithm had been implemented on a PC using the C programming language. However, the PC did not have sufficient sequential processing power to handle real-time extraction, processing and reduction required when the LRF algorithm was applied to real-time video from fast, high-resolution image sensors. This thesis describes two hardware implementations of the LRF algorithm to achieve real-time image processing. The first was created with a VIRTEX-7 field programmable gate array (FPGA). The other developed using the graphics processing unit (GPU) of a NVIDIA GeForce GTX 690 video card. The novelty in the FPGA approach is the creation of a "black box" LRF video processing system with a general camera link input, a user controller interface, and a camera link video output. We also describe a custom hardware simulation environment we have built to test the FPGA LRF implementation. The advantage of the GPU approach is significantly improved development time, integration of image stabilization into the system, and comparable atmospheric turbulence mitigation.

  7. Physics of Non-Inertial Reference Frames

    NASA Astrophysics Data System (ADS)

    Kamalov, Timur F.

    2010-12-01

    Physics of non-inertial reference frames is a generalizing of Newton's laws to any reference frames. It is the system of general axioms for classical and quantum mechanics. The first, Kinematics Principle reads: the kinematic state of a body free of forces conserves and equal in absolute value to an invariant of the observer's reference frame. The second, Dynamics Principle extended Newton's second law to non-inertial reference frames and also contains additional variables there are higher derivatives of coordinates. Dynamics Principle reads: a force induces a change in the kinematic state of the body and is proportional to the rate of its change. It is mean that if the kinematic invariant of the reference frame is n-th derivative with respect the time, then the dynamics of a body being affected by the force F is described by the 2n-th differential equation. The third, Statics Principle reads: the sum of all forces acting a body at rest is equal to zero.

  8. Physics of Non-Inertial Reference Frames

    SciTech Connect

    Kamalov, Timur F.

    2010-12-22

    Physics of non-inertial reference frames is a generalizing of Newton's laws to any reference frames. It is the system of general axioms for classical and quantum mechanics. The first, Kinematics Principle reads: the kinematic state of a body free of forces conserves and equal in absolute value to an invariant of the observer's reference frame. The second, Dynamics Principle extended Newton's second law to non-inertial reference frames and also contains additional variables there are higher derivatives of coordinates. Dynamics Principle reads: a force induces a change in the kinematic state of the body and is proportional to the rate of its change. It is mean that if the kinematic invariant of the reference frame is n-th derivative with respect the time, then the dynamics of a body being affected by the force F is described by the 2n-th differential equation. The third, Statics Principle reads: the sum of all forces acting a body at rest is equal to zero.

  9. Backreaction of frame dragging

    SciTech Connect

    Herdeiro, Carlos A. R.; Rebelo, Carmen; Warnick, Claude M.

    2009-10-15

    The backreaction on black holes due to dragging heavy, rather than test, objects is discussed. As a case study, a five-dimensional regular black Saturn system where the central black hole has vanishing intrinsic angular momentum, J{sup BH}=0, is considered. It is shown that there is a correlation between the sign of two response functions. One is interpreted as a moment of inertia of the black ring in the black Saturn system. The other measures the variation of the black ring horizon angular velocity with the central black hole mass, for fixed ring mass and angular momentum. The two different phases defined by these response functions collapse, for small central black hole mass, to the thin and fat ring phases. In the fat phase, the zero area limit of the black Saturn ring has reduced spin j{sup 2}>1, which is related to the behavior of the ring angular velocity. Using the 'gravitomagnetic clock effect', for which a universality property is exhibited, it is shown that frame dragging measured by an asymptotic observer decreases, in both phases, when the central black hole mass increases, for fixed ring mass and angular momentum. A close parallelism between the results for the fat phase and those obtained recently for the double Kerr solution is drawn, considering also a regular black Saturn system with J{sup BH}{ne}0.

  10. Backreaction of frame dragging

    NASA Astrophysics Data System (ADS)

    Herdeiro, Carlos A. R.; Rebelo, Carmen; Warnick, Claude M.

    2009-10-01

    The backreaction on black holes due to dragging heavy, rather than test, objects is discussed. As a case study, a five-dimensional regular black Saturn system where the central black hole has vanishing intrinsic angular momentum, JBH=0, is considered. It is shown that there is a correlation between the sign of two response functions. One is interpreted as a moment of inertia of the black ring in the black Saturn system. The other measures the variation of the black ring horizon angular velocity with the central black hole mass, for fixed ring mass and angular momentum. The two different phases defined by these response functions collapse, for small central black hole mass, to the thin and fat ring phases. In the fat phase, the zero area limit of the black Saturn ring has reduced spin j2>1, which is related to the behavior of the ring angular velocity. Using the “gravitomagnetic clock effect,” for which a universality property is exhibited, it is shown that frame dragging measured by an asymptotic observer decreases, in both phases, when the central black hole mass increases, for fixed ring mass and angular momentum. A close parallelism between the results for the fat phase and those obtained recently for the double Kerr solution is drawn, considering also a regular black Saturn system with JBH≠0.

  11. Real-time dual-mode standard/complex Fourier-domain OCT system using graphics processing unit accelerated 4D signal processing and visualization

    NASA Astrophysics Data System (ADS)

    Zhang, Kang; Kang, Jin U.

    2011-03-01

    We realized a real-time dual-mode standard/complex Fourier-domain optical coherence tomography (FD-OCT) system using graphics processing unit (GPU) accelerated 4D (3D+time) signal processing and visualization. For both standard and complex FD-OCT modes, the signal processing tasks were implemented on a dual-GPUs architecture that included λ-to-k spectral re-sampling, fast Fourier transform (FFT), modified Hilbert transform, logarithmic-scaling, and volume rendering. The maximum A-scan processing speeds achieved are >3,000,000 line/s for the standard 1024-pixel-FD-OCT, and >500,000 line/s for the complex 1024-pixel-FD-OCT. Multiple volumerendering of the same 3D data set were preformed and displayed with different view angles. The GPU-acceleration technique is highly cost-effective and can be easily integrated into most ultrahigh speed FD-OCT systems to overcome the 3D data processing and visualization bottlenecks.

  12. Neutron energy and time-of-flight spectra behind the lateral shield of a high energy electron accelerator beam dump. Part II: Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Roesler, S.; Liu, J. C.; Rokni, S. H.; Taniguchi, S.

    2003-05-01

    Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight spectra were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators.

  13. Ultra-high speed burst-mode imager for multi-frame radiography

    SciTech Connect

    Kwiatkowski, Kris; Nedrow, Paul; Mariam, Fesseha; Merrill, Frank E; Morris, Chris L; Saunders, Abdy; Hogan, Gary; Douance, Vincent; Bal, Yibin; Joshi, Atul; Auyeung, John

    2010-01-01

    A 720 x 720 pixel hybrid-CMOS imager was fabricated by Rockwell Scientific (now Teledyne Imaging Sensors). Several cameras have been in operation for 5 years, in a variety of static and dynamic experiments, at the 800MeV proton radiography (pRAD) facility at the LANSCE accelerator. The cameras can operate with a per-pulse adjustable inter-frame time of 250ns to 2s, and with an exposure/integration-time as short as 150 ns. Given the 800 ms total readout time, the imager can be externally synchronized to 0.1-to-5Hz, 50-ns wide proton beam pulses, and record 1000-frame radiographic movies of 5-to-30 minute duration. The effectiveness and dependence of the global electronic shutter on the pixelated Si photo-sensor bias voltage is discussed. The spatial resolution dependence of the full imaging system on various monolithic and structured scintillators is presented. We also present features of a new-generation 10-frame, 1024 x 1024 pixel, 50-ns exposure, 12-bit dynamic range imager, which is now in the design phase.

  14. Advanced Wall Framing; BTS Technology Fact Sheet

    SciTech Connect

    Southface Energy Institute; Tromly, K.

    2000-11-07

    Advanced framing techniques for home construction have been researched extensively and proven effective. Both builders and home owners can benefit from advanced framing. Advanced framing techniques create a structurally sound home that has lower material and labor costs than a conventionally framed house. This fact sheet describes advanced framing techniques, design considerations, and framing.

  15. Accelerating Ground-Test Cycle Time: The Six-Minute Model Change and Other Visions for the 21st Century

    NASA Technical Reports Server (NTRS)

    Kegelman, Jerome T.

    1998-01-01

    The advantage of managing organizations to minimize product development cycle time has been well established. This paper provides an overview of the wind tunnel testing cycle time reduction activities at Langley Research Center (LaRC) and gives the status of several improvements in the wind tunnel productivity and cost reductions that have resulted from these activities. Processes have been examined and optimized. Metric data from monitoring processes provides guidance for investments in advanced technologies. The most promising technologies under implementation today include the use of formally designed experiments, a diverse array of quick disconnect technology and the judicious use of advanced electronic and information technologies.

  16. Accelerated autoantibody clearance by intravenous immunoglobulin therapy: studies in experimental models to determine the magnitude and time course of the effect.

    PubMed

    Bleeker, W K; Teeling, J L; Hack, C E

    2001-11-15

    Recently, it has been postulated that the beneficial effect of intravenous immunoglobulins (IVIGs) in antibody-mediated autoimmune disorders is based on accelerated catabolism of autoantibodies. In the current study, in vivo experiments were performed with mice in which autoantibody production was mimicked by continuous infusion of monoclonal antibodies. In this model, a single dose of IVIG reduced the plasma concentrations of the infused immunoglobulin (Ig)G1 monoclonal antibody (mAb) by approximately 40% after 3 days, whereas the concentration of an IgA mAb was not affected. To extrapolate these findings to humans, a computational model for IgG clearance was established that accurately predicted the time course and magnitude of the decrease in IgG plasma levels observed in mice. Adapted for humans, this model predicted a gradually occurring decrease in autoantibody levels after IVIG administration (2 g/kg), with a maximum reduction of approximately 25% after 3 to 4 weeks and a continued decrease of several months. In conclusion, a single high dose of IVIG induces a relatively small but long-lasting reduction of autoantibody levels by accelerated IgG clearance. This mechanism has clinical relevance in the sense that it can fully explain, as the sole mechanism, the gradual decrease in autoantibody levels observed in several patient studies. However, in some clinical studies, larger or more rapid effects have been observed that cannot be explained by accelerated clearance. Hence, IVIG can also reduce autoantibody levels through mechanisms such as down-regulation of antibody production or neutralization by anti-idiotypic antibodies.

  17. Putting a Frame on Leadership

    ERIC Educational Resources Information Center

    Dexter, Robin R.; Berube, William B.; Perry, Suzanne M.; Stader, David L.

    2005-01-01

    Teachers are learning more about the theories that support conceptual frameworks as a learning tool. A literature review revealed that frame theory is an accepted principle used to describe how the brain organizes experiences and new information. Frame theory supports the understanding that individuals can organize their thoughts to better…

  18. Calculating body frame size (image)

    MedlinePlus

    ... boned category. Determining frame size: To determine the body frame size, measure the wrist with a tape measure and use the following chart to determine whether the person is small, medium, or large boned. Women: Height under 5'2" Small = wrist size less ...

  19. RAM-Based frame synchronizer

    NASA Technical Reports Server (NTRS)

    Niswander, J. K.; Stattel, R. J.

    1980-01-01

    Frame synchronizer for serial telemetry is rapidly reconfigured for changing formats. Synchronizer generates signals marking data-word boundaries, beginning of each frame, and beginning of each paragraph. Also derived are search, check, and lock status signals. Existing unit is assembled from standard random-access memory elements and MOS and low-power-Schottky logic.

  20. FRAMES and Other IEM Technologies

    EPA Science Inventory

    A presentation package is developed that describes the FRAMES software technology system. The philosophy of FRAMES is discussed; its components and editors are reviewed; its relationship to integrated environmental modeling technologies; such as D4EM and SuperMUSE, are described;...

  1. The Semantics of Syntactic Frames

    ERIC Educational Resources Information Center

    Kako, Edward

    2006-01-01

    Research in psychology and in linguistics has converged to suggest that the syntactic frames in which verbs appear carry meanings of their own, apart from the meaning of the verbs themselves. To date, however, a gap has existed between these two lines of research: Research in psychology has inferred the meanings of frames only indirectly; research…

  2. Blip decomposition of the path integral: Exponential acceleration of real-time calculations on quantum dissipative systems

    SciTech Connect

    Makri, Nancy

    2014-10-07

    The real-time path integral representation of the reduced density matrix for a discrete system in contact with a dissipative medium is rewritten in terms of the number of blips, i.e., elementary time intervals over which the forward and backward paths are not identical. For a given set of blips, it is shown that the path sum with respect to the coordinates of all remaining time points is isomorphic to that for the wavefunction of a system subject to an external driving term and thus can be summed by an inexpensive iterative procedure. This exact decomposition reduces the number of terms by a factor that increases exponentially with propagation time. Further, under conditions (moderately high temperature and/or dissipation strength) that lead primarily to incoherent dynamics, the “fully incoherent limit” zero-blip term of the series provides a reasonable approximation to the dynamics, and the blip series converges rapidly to the exact result. Retention of only the blips required for satisfactory convergence leads to speedup of full-memory path integral calculations by many orders of magnitude.

  3. Theory, implementation and applications of nonstationary Gabor frames

    PubMed Central

    Balazs, P.; Dörfler, M.; Jaillet, F.; Holighaus, N.; Velasco, G.

    2011-01-01

    Signal analysis with classical Gabor frames leads to a fixed time–frequency resolution over the whole time–frequency plane. To overcome the limitations imposed by this rigidity, we propose an extension of Gabor theory that leads to the construction of frames with time–frequency resolution changing over time or frequency. We describe the construction of the resulting nonstationary Gabor frames and give the explicit formula for the canonical dual frame for a particular case, the painless case. We show that wavelet transforms, constant-Q transforms and more general filter banks may be modeled in the framework of nonstationary Gabor frames. Further, we present the results in the finite-dimensional case, which provides a method for implementing the above-mentioned transforms with perfect reconstruction. Finally, we elaborate on two applications of nonstationary Gabor frames in audio signal processing, namely a method for automatic adaptation to transients and an algorithm for an invertible constant-Q transform. PMID:22267893

  4. Aging and Tennis Playing in a Coincidence-Timing Task with an Accelerating Object: The Role of Visuomotor Delay

    ERIC Educational Resources Information Center

    Lobjois, Regis; Benguigui, Nicolas; Bertsch, Jean

    2005-01-01

    The purpose of the present study was to determine whether playing a specific ball sport, such as tennis, could maintain the coincidence-timing (CT) performance of older adults at a similar level to that of younger ones. To address this question, tennis players and nonplayers of three different age ranges (ages 20-30, 60-70, and 70-80 years)…

  5. Arsenic trioxide inhibits accelerated allograft rejection mediated by alloreactive CD8(+) memory T cells and prolongs allograft survival time.

    PubMed

    Li, Chun; Guan, Tianjun; Gao, Chang; Lin, Yingying; Yan, Guoliang; Zhu, Maoshu; Lv, Chongshan; Xia, Junjie; Qi, Zhongquan

    2015-09-01

    CD8(+) memory T (Tm) cells are a significant barrier to transplant tolerance induction in alloantigen-primed recipients, and are insensitive to existing clinical immunosuppressants. Here, we studied the inhibition of CD8(+) Tm cells by arsenic trioxide (As2O3) for the first time. Alloantigen-primed CD8(+) Tm cells were transferred to T cell immunodeficient nude mice. The mice were subjected to heart allotransplantation, and treated with As2O3. The transplant survival time was determined, and the inhibitory effects of As2O3 on CD8(+) Tm cell-mediated immune rejection were assessed through serological studies and inspection of the transplanted heart and lymphoid organs. We found that As2O3 treatment prolonged the mean survival time of the graft and reduced the number of CD8(+) Tm cells in the spleen and lymph nodes. The expression of the genes encoding interleukin (IL)-2, and IFN-γ was reduced, while expression of IL-10 and transforming growth factor-β was increased in the transplant. Our findings show that As2O3 treatment inhibits allograft rejection mediated by alloreactive CD8(+) Tm cells in the mouse heart transplantation model.

  6. GPU accelerated fully space and time resolved numerical simulations of self-focusing laser beams in SBS-active media

    SciTech Connect

    Mauger, Sarah; Colin de Verdière, Guillaume; Bergé, Luc; Skupin, Stefan

    2013-02-15

    A computer cluster equipped with Graphics Processing Units (GPUs) is used for simulating nonlinear optical wave packets undergoing Kerr self-focusing and stimulated Brillouin scattering in fused silica. We first recall the model equations in full (3+1) dimensions. These consist of two coupled nonlinear Schrödinger equations for counterpropagating optical beams closed with a source equation for light-induced acoustic waves seeded by thermal noise. Compared with simulations on a conventional cluster of Central Processing Units (CPUs), GPU-based computations allow us to use a significant (16 times) larger number of mesh points within similar computation times. Reciprocally, simulations employing the same number of mesh points are between 3 and 20 times faster on GPUs than on the same number of classical CPUs. Performance speedups close to 45 are reported for isolated functions evaluating, e.g., the optical nonlinearities. Since the field intensities may reach the ionization threshold of silica, the action of a defocusing electron plasma is also addressed.

  7. Cosmology of a Friedmann-Lamaître-Robertson-Walker 3-brane, late-time cosmic acceleration, and the cosmic coincidence.

    PubMed

    Doolin, Ciaran; Neupane, Ishwaree P

    2013-04-01

    A late epoch cosmic acceleration may be naturally entangled with cosmic coincidence--the observation that at the onset of acceleration the vacuum energy density fraction nearly coincides with the matter density fraction. In this Letter we show that this is indeed the case with the cosmology of a Friedmann-Lamaître-Robertson-Walker (FLRW) 3-brane in a five-dimensional anti-de Sitter spacetime. We derive the four-dimensional effective action on a FLRW 3-brane, from which we obtain a mass-reduction formula, namely, M(P)(2) = ρ(b)/|Λ(5)|, where M(P) is the effective (normalized) Planck mass, Λ(5) is the five-dimensional cosmological constant, and ρ(b) is the sum of the 3-brane tension V and the matter density ρ. Although the range of variation in ρ(b) is strongly constrained, the big bang nucleosynthesis bound on the time variation of the effective Newton constant G(N) = (8πM(P)(2))(-1) is satisfied when the ratio V/ρ ≳ O(10(2)) on cosmological scales. The same bound leads to an effective equation of state close to -1 at late epochs in accordance with astrophysical and cosmological observations.

  8. Cosmology of a Friedmann-Lamaître-Robertson-Walker 3-brane, late-time cosmic acceleration, and the cosmic coincidence.

    PubMed

    Doolin, Ciaran; Neupane, Ishwaree P

    2013-04-01

    A late epoch cosmic acceleration may be naturally entangled with cosmic coincidence--the observation that at the onset of acceleration the vacuum energy density fraction nearly coincides with the matter density fraction. In this Letter we show that this is indeed the case with the cosmology of a Friedmann-Lamaître-Robertson-Walker (FLRW) 3-brane in a five-dimensional anti-de Sitter spacetime. We derive the four-dimensional effective action on a FLRW 3-brane, from which we obtain a mass-reduction formula, namely, M(P)(2) = ρ(b)/|Λ(5)|, where M(P) is the effective (normalized) Planck mass, Λ(5) is the five-dimensional cosmological constant, and ρ(b) is the sum of the 3-brane tension V and the matter density ρ. Although the range of variation in ρ(b) is strongly constrained, the big bang nucleosynthesis bound on the time variation of the effective Newton constant G(N) = (8πM(P)(2))(-1) is satisfied when the ratio V/ρ ≳ O(10(2)) on cosmological scales. The same bound leads to an effective equation of state close to -1 at late epochs in accordance with astrophysical and cosmological observations. PMID:25166976

  9. Cosmology of a Friedmann-Lamaître-Robertson-Walker 3-Brane, Late-Time Cosmic Acceleration, and the Cosmic Coincidence

    NASA Astrophysics Data System (ADS)

    Doolin, Ciaran; Neupane, Ishwaree P.

    2013-04-01

    A late epoch cosmic acceleration may be naturally entangled with cosmic coincidence—the observation that at the onset of acceleration the vacuum energy density fraction nearly coincides with the matter density fraction. In this Letter we show that this is indeed the case with the cosmology of a Friedmann-Lamaître-Robertson-Walker (FLRW) 3-brane in a five-dimensional anti-de Sitter spacetime. We derive the four-dimensional effective action on a FLRW 3-brane, from which we obtain a mass-reduction formula, namely, MP2=ρb/|Λ5|, where MP is the effective (normalized) Planck mass, Λ5 is the five-dimensional cosmological constant, and ρb is the sum of the 3-brane tension V and the matter density ρ. Although the range of variation in ρb is strongly constrained, the big bang nucleosynthesis bound on the time variation of the effective Newton constant GN=(8πMP2)-1 is satisfied when the ratio V/ρ≳O(102) on cosmological scales. The same bound leads to an effective equation of state close to -1 at late epochs in accordance with astrophysical and cosmological observations.

  10. Shadowgraph illumination techniques for framing cameras

    SciTech Connect

    Malone, R.M.; Flurer, R.L.; Frogget, B.C.; Sorenson, D.S.; Holmes, V.H.; Obst, A.W.

    1997-06-01

    Many pulse power applications in use at the Pegasus facility at the Los Alamos National Laboratory require specialized imaging techniques. Due to the short event duration times, visible images are recorded by high speed electronic framing cameras. Framing cameras provide the advantages of high speed movies of back light experiments. These high speed framing cameras require bright illumination sources to record images with 10 ns integration times. High power lasers offer sufficient light for back illuminating the target assemblies; however, laser speckle noise lowers the contrast in the image. Laser speckle noise also limits the effective resolution. This discussion focuses on the use of telescopes to collect images 50 feet away. Both light field and dark field illumination techniques are compared. By adding relay lenses between the assembly target and the telescope, a high resolution magnified image can be recorded. For dark field illumination, these relay lenses can be used to separate the object field from the illumination laser. The illumination laser can be made to focus onto the opaque secondary of a Schmidt telescope. Thus, the telescope only collects scattered light from the target assembly. This dark field illumination eliminates the laser speckle noise and allows high resolution images to be recorded. Using the secondary of the telescope to block the illumination laser makes dark field illumination an ideal choice for the framing camera.

  11. Cultural background shapes spatial reference frame proclivity

    PubMed Central

    Goeke, Caspar; Kornpetpanee, Suchada; Köster, Moritz; Fernández-Revelles, Andrés B.; Gramann, Klaus; König, Peter

    2015-01-01

    Spatial navigation is an essential human skill that is influenced by several factors. The present study investigates how gender, age, and cultural background account for differences in reference frame proclivity and performance in a virtual navigation task. Using an online navigation study, we recorded reaction times, error rates (confusion of turning axis), and reference frame proclivity (egocentric vs. allocentric reference frame) of 1823 participants. Reaction times significantly varied with gender and age, but were only marginally influenced by the cultural background of participants. Error rates were in line with these results and exhibited a significant influence of gender and culture, but not age. Participants’ cultural background significantly influenced reference frame selection; the majority of North-Americans preferred an allocentric strategy, while Latin-Americans preferred an egocentric navigation strategy. European and Asian groups were in between these two extremes. Neither the factor of age nor the factor of gender had a direct impact on participants’ navigation strategies. The strong effects of cultural background on navigation strategies without the influence of gender or age underlines the importance of socialized spatial cognitive processes and argues for socio-economic analysis in studies investigating human navigation. PMID:26073656

  12. Intra-cyclic distance per stroke phase, velocity fluctuations and acceleration time ratio of a breaststroker's hip: a comparison between elite and nonelite swimmers at different race paces.

    PubMed

    Leblanc, H; Seifert, L; Tourny-Chollet, C; Chollet, D

    2007-02-01

    The aim of this study was to compare the intra-cyclic velocity graphs of breaststroke swimmers at two skill levels in relation to their movement phases. Two groups of nine male swimmers were videotaped underwater at three swimming race paces corresponding to their actual competitive times for the 200-m, 100-m and 50-m breaststroke. Their forward intra-cyclic hip velocity was recorded with a velocity-meter. The breaststroke cycle was divided into four phases: leg propulsion, leg-arm lag phase, arm propulsion, and arm and leg recovery. From the velocity-time data, the following parameters were computed: an index of velocity fluctuations (IVF), the distance covered during each stroke phase, and an acceleration-deceleration time ratio (ADTR). The main results showed that in both groups of swimmers, when the race pace increased, the distance covered during the leg-arm lag phase decreased, while the other swimming phases remained stable. When expressed in relative values, the percentage of distance covered during the leg-arm lag phase decreased. In nonelite swimmers, the percentage of distance covered in the other stroke phases increased significantly, while only a tendency was noted in the elite group. Elite swimmers demonstrated a higher ADTR at the 50-m pace than at their 100-m and 200-m paces. An inter-group comparison showed that elite swimmers had higher values for the IVF and ADTR, which indicated their capacity to accelerate to boost the swim and highlighted the relevancy of these factors to discriminate skill level. PMID:16835822

  13. Real time dynamic MRI by exploiting spatial and temporal sparsity.

    PubMed

    Chen, Chen; Li, Yeqing; Axel, Leon; Huang, Junzhou

    2016-05-01

    Online imaging requires that the reconstruction of current frame only depends on the previous frames, and real time imaging is the desired case. In this work, we propose a novel scheme for real time dynamic magnetic resonance imaging (dMRI) reconstruction. Different from previous methods, the reconstructions of the second frame to the last frame are independent in our scheme, which only require the first frame as the reference image. Therefore, this scheme can be naturally implemented in parallel. After the first frame is reconstructed, all the later frames can be processed as soon as the k-space data are acquired. As an extension of the conventional spatial total variation, a new online model called dynamic total variation is used to exploit the sparsity on both spatial and temporal domains in dMRI. In real time dMRI, each frame is required to be reconstructed very fast. We then design a novel reweighted least squares algorithm to solve the challenging problem. Motivated by the special structure of partial Fourier transform in sparse MRI, this algorithm is accelerated by the preconditioned conjugate gradient descent method. The proposed method is compared with 4 state-of-the-art online and offline methods on two in-vivo cardiac dMRI datasets. The experimental results show that our method significantly outperforms previous online methods, and is comparable to the offline methods in terms of reconstruction accuracy. PMID:26578303

  14. Framed School--Frame Factors, Frames and the Dynamics of Social Interaction in School

    ERIC Educational Resources Information Center

    Persson, Anders

    2015-01-01

    This paper aims to show how the Goffman frame perspective can be used in an analysis of school and education and how it can be combined, in such analysis, with the frame factor perspective. The latter emphasizes factors that are determined outside the teaching process, while the former stresses how actors organize their experiences and define…

  15. Accelerated increase in mercury contamination in north Atlantic mesopelagic food chains as indicated by time series of seabird feathers

    SciTech Connect

    Monteiro, L.R.; Furness, R.W.

    1997-12-01

    Concentrations of mercury in the environment have increased manyfold since preindustrial times as a result of anthropogenic emissions of gaseous mercury to the atmosphere. However, most records of historical change are affected by regional inputs and evidence of global impact of human activities at pristine oceanic sites is scanty. Seabird feathers contain a valuable record showing historical trends in methylmercury contamination. Some seabirds are top predators in epipelagic and others in mesopelagic food chains and thus reflect methylmercury contamination of these ecosystems. Here, the authors report the first measurements of mercury concentrations in a time series of animals from the subtropical northeast Atlantic over the last 100 years. These data show increases in mercury levels by 1.1 to 1.9%/year in epipelagic foodchains and by 3.5 to 4.8%/year in mesopelagic food chains. While the rate of increase in the epipelagic ecosystem is in close agreement with model predictions, the higher rate in the mesopelagic ecosystem has not previously been detected. However, the latter concurs with methylmercury production below the thermocline and conveys new insights into the understanding of the anthropogenic impact in the marine cycle of mercury.

  16. Framing Obesity: How News Frames Shape Attributions and Behavioral Responses.

    PubMed

    Sun, Ye; Krakow, Melinda; John, Kevin K; Liu, Miao; Weaver, Jeremy

    2016-01-01

    Based on a public health model of obesity, this study set out to examine whether a news article reporting the obesity issue in a societal versus individual frame would increase perceptions of societal responsibilities for the obesity problem and motivate responsibility-taking behaviors. Responsibility-taking behaviors were examined at 3 levels: personal, interpersonal, and societal. Data from a Web-based experiment revealed significant framing effects on behaviors via causal and treatment responsibility attributions. The societal frame increased societal causal and treatment attribution, which led to greater likelihoods of interpersonal and social responsibility-taking behaviors as well as personal behaviors. Our findings suggest that news framing can be an effective venue for raising awareness of obesity as a societal issue and mobilizing collective efforts. PMID:26375052

  17. Self-Organizing Hierarchical Particle Swarm Optimization with Time-Varying Acceleration Coefficients for Economic Dispatch with Valve Point Effects and Multifuel Options

    NASA Astrophysics Data System (ADS)

    Polprasert, Jirawadee; Ongsakul, Weerakorn; Dieu, Vo Ngoc

    2011-06-01

    This paper proposes a self-organizing hierarchical particle swarm optimization (SPSO) with time-varying acceleration coefficients (TVAC) for solving economic dispatch (ED) problem with non-smooth functions including multiple fuel options (MFO) and valve-point loading effects (VPLE). The proposed SPSO with TVAC is the new approach optimizer and good performance for solving ED problems. It can handle the premature convergence of the problem by re-initialization of velocity whenever particles are stagnated in the search space. To properly control both local and global explorations of the swarm during the optimization process, the performance of TVAC is included. The proposed method is tested in different ED problems with non-smooth cost functions and the obtained results are compared to those from many other methods in the literature. The results have revealed that the proposed SPSO with TVAC is effective in finding higher quality solutions for non-smooth ED problems than many other methods.

  18. Electrostatic design and beam transport for a folded tandem electrostatic quadrupole accelerator facility for accelerator-based boron neutron capture therapy.

    PubMed

    Vento, V Thatar; Bergueiro, J; Cartelli, D; Valda, A A; Kreiner, A J

    2011-12-01

    Within the frame of an ongoing project to develop a folded Tandem-Electrostatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT), we discuss here the electrostatic design of the machine, including the accelerator tubes with electrostatic quadrupoles and the simulations for the transport and acceleration of a high intensity beam.

  19. Implications of an absolute simultaneity theory for cosmology and universe acceleration.

    PubMed

    Kipreos, Edward T

    2014-01-01

    An alternate Lorentz transformation, Absolute Lorentz Transformation (ALT), has similar kinematics to special relativity yet maintains absolute simultaneity in the context of a preferred reference frame. In this study, it is shown that ALT is compatible with current experiments to test Lorentz invariance only if the proposed preferred reference frame is locally equivalent to the Earth-centered non-rotating inertial reference frame, with the inference that in an ALT framework, preferred reference frames are associated with centers of gravitational mass. Applying this theoretical framework to cosmological data produces a scenario of universal time contraction in the past. In this scenario, past time contraction would be associated with increased levels of blueshifted light emissions from cosmological objects when viewed from our current perspective. The observation that distant Type Ia supernovae are dimmer than predicted by linear Hubble expansion currently provides the most direct evidence for an accelerating universe. Adjusting for the effects of time contraction on a redshift-distance modulus diagram produces a linear distribution of supernovae over the full redshift spectrum that is consistent with a non-accelerating universe. PMID:25536116

  20. Implications of an Absolute Simultaneity Theory for Cosmology and Universe Acceleration

    PubMed Central

    Kipreos, Edward T.

    2014-01-01

    An alternate Lorentz transformation, Absolute Lorentz Transformation (ALT), has similar kinematics to special relativity yet maintains absolute simultaneity in the context of a preferred reference frame. In this study, it is shown that ALT is compatible with current experiments to test Lorentz invariance only if the proposed preferred reference frame is locally equivalent to the Earth-centered non-rotating inertial reference frame, with the inference that in an ALT framework, preferred reference frames are associated with centers of gravitational mass. Applying this theoretical framework to cosmological data produces a scenario of universal time contraction in the past. In this scenario, past time contraction would be associated with increased levels of blueshifted light emissions from cosmological objects when viewed from our current perspective. The observation that distant Type Ia supernovae are dimmer than predicted by linear Hubble expansion currently provides the most direct evidence for an accelerating universe. Adjusting for the effects of time contraction on a redshift–distance modulus diagram produces a linear distribution of supernovae over the full redshift spectrum that is consistent with a non-accelerating universe. PMID:25536116