Science.gov

Sample records for accelerator complex consists

  1. Acceleration of polarized protons in the IHEP accelerator complex

    SciTech Connect

    Anferov, V.A.; Ado, Yu.M.; Shoumkin, D.

    1995-04-01

    The paper considers possibility to accelerate polarized beam in the IHEP accelerator complex (including first stage of the UNK). The scheme of preserving beam polarization is described for all acceleration stages up to 400 GeV beam energy. Polarization and intensity of the polarized proton beam are estimated. The suggested scheme includes using two Siberian snakes in opposite straight sections of the UNK-1, where each snake consists of five dipole magnets. In the U-70 it is suggested to use one helical Siberian snake, which is turned on adiabatically at 10 GeV, and four pulsed quadrupoles. To incorporate the snake into the accelerator lattice it is proposed to make modification of one superperiod. This would make a 13 m long straight section. Spin depolarization in the Booster is avoided by decreasing the extraction energy to 0.9 GeV. Then no additional hardware is required in the Booster.

  2. Martial arts striking hand peak acceleration, accuracy and consistency.

    PubMed

    Neto, Osmar Pinto; Marzullo, Ana Carolina De Miranda; Bolander, Richard P; Bir, Cynthia A

    2013-01-01

    The goal of this paper was to investigate the possible trade-off between peak hand acceleration and accuracy and consistency of hand strikes performed by martial artists of different training experiences. Ten male martial artists with training experience ranging from one to nine years volunteered to participate in the experiment. Each participant performed 12 maximum effort goal-directed strikes. Hand acceleration during the strikes was obtained using a tri-axial accelerometer block. A pressure sensor matrix was used to determine the accuracy and consistency of the strikes. Accuracy was estimated by the radial distance between the centroid of each subject's 12 strikes and the target, whereas consistency was estimated by the square root of the 12 strikes mean squared distance from their centroid. We found that training experience was significantly correlated to hand peak acceleration prior to impact (r(2)=0.456, p =0.032) and accuracy (r(2)=0. 621, p=0.012). These correlations suggest that more experienced participants exhibited higher hand peak accelerations and at the same time were more accurate. Training experience, however, was not correlated to consistency (r(2)=0.085, p=0.413). Overall, our results suggest that martial arts training may lead practitioners to achieve higher striking hand accelerations with better accuracy and no change in striking consistency.

  3. The Tandem-ALPI-PIAVE accelerator complex of LNL

    SciTech Connect

    Ur, C. A.

    2013-07-18

    Heavy ion beams are delivered at the Laboratori Nazionali di Legnaro by the accelerator complex Tandem-ALPI-PIAVE. The Tandem XTU is a Van de Graaff accelerator normally operated at terminal voltages of up to about 15 MV. The Tandem accelerator can be operated in stand-alone mode or as an injector for the linac booster ALPI. The linear accelerator ALPI is built of superconducting resonant cavities and consists of a low-beta branch, particularly important for the acceleration of the heavier mass ions, a medium-beta branch, and a high-beta branch. ALPI can be operated also with the PIAVE injector that consists of a superconducting linac and an ECR source. The PIAVE source was mainly used for the acceleration of intense noble gas beams but most recently also a first metallic beam was delivered to the users. The accelerator complex delivers beams of ions from protons to gold in three experimental areas on 11 different beam lines. A rich scientific activity is ongoing at the Tandem-ALPI-PIAVE accelerator complex, beam time being shared between nuclear physics research and applied and interdisciplinary physics research. An overview of the present status and perspectives of the Tandem-ALPI-PIAVE complex and its physics program is given in the present paper.

  4. VIEW OF COMPLEX OF BUILDINGS CONSISTING OF A THREESTORY REINFORCED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF COMPLEX OF BUILDINGS CONSISTING OF A THREE-STORY REINFORCED CONCRETE FACTORY WITH A SMALLER ONE-STORY LOADING DOCK AND ANOTHER ONE-STORY BRICK AND STEEL BUILDING ON THE EAST FACADE. THE THREE-STORY BUILDING HAS VERTICAL METAL PANELING ON THE UPPER STORY. THE ENTIRE COMPLEX IS PAINTED PINK WITH MUCH DAMAGE TO THE EXTERIOR OF THE BUILDING ON THE SOUTH SIDE - American Can Company, 1400 Trombly Avenue, Detroit, MI

  5. VIEW OF COMPLEX OF BUILDINGS CONSISTING OF A THREESTORY REINFORCED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF COMPLEX OF BUILDINGS CONSISTING OF A THREE-STORY REINFORCED CONCRETE FACTORY WITH A SMALLER ONE-STORY LOADING DOCK AND ANOTHER ONE-STORY BRICK AND STEEL BUILDING ON THE EAST FACADE. THE THREE-STORY BUILDING HAS VERTICAL METAL PANELING ON THE UPPER STORY. THE ENTIRE COMPLEX IS PAINTED PINK WITH MUCH DAMAGE TO THE EXTERIOR OF THE BUILDING ON THE SOUTH SIDE. (Duplicate color view of HAER MI-340-1) - American Can Company, 1400 Trombly Avenue, Detroit, MI

  6. Pattern formation in oscillatory complex networks consisting of excitable nodes

    NASA Astrophysics Data System (ADS)

    Liao, Xuhong; Xia, Qinzhi; Qian, Yu; Zhang, Lisheng; Hu, Gang; Mi, Yuanyuan

    2011-05-01

    Oscillatory dynamics of complex networks has recently attracted great attention. In this paper we study pattern formation in oscillatory complex networks consisting of excitable nodes. We find that there exist a few center nodes and small skeletons for most oscillations. Complicated and seemingly random oscillatory patterns can be viewed as well-organized target waves propagating from center nodes along the shortest paths, and the shortest loops passing through both the center nodes and their driver nodes play the role of oscillation sources. Analyzing simple skeletons we are able to understand and predict various essential properties of the oscillations and effectively modulate the oscillations. These methods and results will give insights into pattern formation in complex networks and provide suggestive ideas for studying and controlling oscillations in neural networks.

  7. Synchronization in node of complex networks consist of complex chaotic system

    SciTech Connect

    Wei, Qiang; Xie, Cheng-jun; Liu, Hong-jun; Li, Yan-hui

    2014-07-15

    A new synchronization method is investigated for node of complex networks consists of complex chaotic system. When complex networks realize synchronization, different component of complex state variable synchronize up to different scaling complex function by a designed complex feedback controller. This paper change synchronization scaling function from real field to complex field for synchronization in node of complex networks with complex chaotic system. Synchronization in constant delay and time-varying coupling delay complex networks are investigated, respectively. Numerical simulations are provided to show the effectiveness of the proposed method.

  8. Consistency in acceleration patterns of football players with different skill levels.

    PubMed

    Arpinar-Avsar, Pinar; Soylu, Abdullah Ruhi

    2010-01-01

    The aims of the present study were to compare the consistency in the lower limb acceleration patterns during inside and instep kicks performed by players with different skill levels, and to investigate the correlation between subjective rating scores for skill level relative to their kicking performance and knee acceleration repeatability. Thirteen club-level male soccer players of ages between 15-16 years participated in this study. Skill levels of individual players were quantified previously by evaluating shooting performance as a numerical value ranging from 1 to 10. Further evaluations were held through tri-axial acceleration data recorded at proximal tibial tuberosity beneath each patella on the players' knees, in a procedure in which players were asked to complete four randomly ordered shooting trials of inside and instep kicks with 2-minute resting intervals. Hence, the mainstream data used in consistency calculations are in the form 4 by 1200 matrices (acceleration vs. time) per subject. In order to evaluate the consistency of acceleration data, the mean of the standard deviations (mSD) were calculated, and the associated Pearson-r correlation coefficients were incorporated to obtain mSD vs. skill correlations. As a result, repeatability was found to increase with skill level at z-axis acceleration for instep kicks only. However, it is possible to find the most appropriate orientation (for the two kicks) for meaningful correlations using vector rotations on the 3 orthogonal acceleration data, and this study shows that, after such suitable vector rotations, positive repeatability results could also be acquired for the inside kicks. Key pointsThe repeatability of the acceleration waveforms are well correlated with the skill level of the subjects.Accelerometry might be used as an objective and cost effective assessment that allows interpreting consistency of the action.

  9. Consistency.

    PubMed

    Levin, Roger

    2005-09-01

    Consistency is a reflection of having the right model, the right systems and the right implementation. As Vince Lombardi, the legendary coach of the Green Bay Packers, once said, "You don't do things right once in a while. You do them right all the time." To provide the ultimate level of patient care, reduce stress for the dentist and staff members and ensure high practice profitability, consistency is key.

  10. A Self-Consistent Beam Loaded Travelling Wave Accelerator Model for use in TRACE-3D

    NASA Astrophysics Data System (ADS)

    Lampel, M. C.

    1997-05-01

    An optics model of a constant gradient traveling wave (CGTW) accelerator structure has been implemented for TRACE-3D. TRACE-3D is an envelope code including space charge that is used to model bunched beams in magnetic transport systems and radio frequency (rf) accelerators when the effects of beam current might be significant. The new matrix model has been developed to allow incorporation of particle beam loading (current) effects on the accelerator gradient and the accelerator structure's beam focusing properties in a self-consistent manner. The beam loaded electric field for a CGTW accelerator structure is constant for only a particular design current (e.g., 0 current), otherwise it can be written as a function of accelerator attenuation and axial position along the structure. The variation of the electric field through the structure has been taken into account in the new model. CGTW structures differ substantially in focusing properties and beam loading properties from standing wave structures. Examples will be presented using the new TW model, propagating electron beams with different currents through the Stanford Linear Accelerator Center's 3 m structure. The results will be compared to the zero current TW structure model in TRANSPORT and the Tank model (a standing wave structure model) in TRACE-3D. A computer demonstration of the code with the new element will also be presented.

  11. Revised fits to Δα/α in consistency with the accelerating universe

    NASA Astrophysics Data System (ADS)

    Fujii, Yasunori

    2009-01-01

    An attempt is made for a new type of analysis of the time-variability of the fine-structure constant trying to fit the most recent result from the laboratory measurements, the Oklo constraint and the data from the QSO absorption lines all in consistency with the accelerating universe.

  12. Wakes in complex plasmas: A self-consistent kinetic theory.

    PubMed

    Kompaneets, Roman; Morfill, Gregor E; Ivlev, Alexei V

    2016-06-01

    In ground-based experiments with complex (dusty) plasmas, charged microparticles are levitated against gravity by an electric field, which also drives ion flow in the parent gas. Existing analytical approaches to describe the electrostatic interaction between microparticles in such conditions generally ignore the field and ion-neutral collisions, assuming free ion flow with a certain approximation for the ion velocity distribution function (usually a shifted Maxwellian). We provide a comprehensive analysis of our previously proposed self-consistent kinetic theory including the field, ion-neutral collisions, and the corresponding ion velocity distribution. We focus on various limiting cases and demonstrate how the interplay of these factors results in different forms of the shielding potential.

  13. Wakes in complex plasmas: A self-consistent kinetic theory

    NASA Astrophysics Data System (ADS)

    Kompaneets, Roman; Morfill, Gregor E.; Ivlev, Alexei V.

    2016-06-01

    In ground-based experiments with complex (dusty) plasmas, charged microparticles are levitated against gravity by an electric field, which also drives ion flow in the parent gas. Existing analytical approaches to describe the electrostatic interaction between microparticles in such conditions generally ignore the field and ion-neutral collisions, assuming free ion flow with a certain approximation for the ion velocity distribution function (usually a shifted Maxwellian). We provide a comprehensive analysis of our previously proposed self-consistent kinetic theory including the field, ion-neutral collisions, and the corresponding ion velocity distribution. We focus on various limiting cases and demonstrate how the interplay of these factors results in different forms of the shielding potential.

  14. Wakes in complex plasmas: A self-consistent kinetic theory.

    PubMed

    Kompaneets, Roman; Morfill, Gregor E; Ivlev, Alexei V

    2016-06-01

    In ground-based experiments with complex (dusty) plasmas, charged microparticles are levitated against gravity by an electric field, which also drives ion flow in the parent gas. Existing analytical approaches to describe the electrostatic interaction between microparticles in such conditions generally ignore the field and ion-neutral collisions, assuming free ion flow with a certain approximation for the ion velocity distribution function (usually a shifted Maxwellian). We provide a comprehensive analysis of our previously proposed self-consistent kinetic theory including the field, ion-neutral collisions, and the corresponding ion velocity distribution. We focus on various limiting cases and demonstrate how the interplay of these factors results in different forms of the shielding potential. PMID:27415371

  15. Modeling Extreme Solar Energetic Particle Acceleration with Self-Consistent Wave Generation

    NASA Astrophysics Data System (ADS)

    Arthur, A. D.; le Roux, J. A.

    2015-12-01

    Observations of extreme solar energetic particle (SEP) events associated with coronal mass ejection driven shocks have detected particle energies up to a few GeV at 1 AU within the first ~10 minutes to 1 hour of shock acceleration. Whether or not acceleration by a single shock is sufficient in these events or if some combination of multiple shocks or solar flares is required is currently not well understood. Furthermore, the observed onset times of the extreme SEP events place the shock in the corona when the particles escape upstream. We have updated our focused transport theory model that has successfully been applied to the termination shock and traveling interplanetary shocks in the past to investigate extreme SEP acceleration in the solar corona. This model solves the time-dependent Focused Transport Equation including particle preheating due to the cross shock electric field and the divergence, adiabatic compression, and acceleration of the solar wind flow. Diffusive shock acceleration of SEPs is included via the first-order Fermi mechanism for parallel shocks. To investigate the effects of the solar corona on the acceleration of SEPs, we have included an empirical model for the plasma number density, temperature, and velocity. The shock acceleration process becomes highly time-dependent due to the rapid variation of these coronal properties with heliocentric distance. Additionally, particle interaction with MHD wave turbulence is modeled in terms of gyroresonant interactions with parallel propagating Alfven waves. However, previous modeling efforts suggest that the background amplitude of the solar wind turbulence is not sufficient to accelerate SEPs to extreme energies over the short time scales observed. To account for this, we have included the transport and self-consistent amplification of MHD waves by the SEPs through wave-particle gyroresonance. We will present the results of this extended model for a single fast quasi-parallel CME driven shock in the

  16. Progress Towards Doubling the Beam Power at Fermilab's Accelerator Complex

    SciTech Connect

    Kourbanis, Ioanis

    2014-07-01

    After a 16 month shutdown to reconfigure the Fermilab Accelerators for high power operations, the Fermilab Accelerator Complex is again providing beams for numerous Physics Experiments. By using the Recycler to slip stack protons while the Main Injector is ramping, the beam power at 120 GeV can reach 700 KW, a factor of 2 increase. The progress towards doubling the Fermilab's Accelerator complex beam power will be presented.

  17. Particle acceleration in the dynamic magnetotail: Orbits in self-consistent three-dimensional MHD fields

    NASA Technical Reports Server (NTRS)

    Birn, Joachim; Hesse, Michael

    1994-01-01

    The acceleration of protons in a dynamically evolving magnetotail is investigated by tracing particles in the fields obtained from a three-dimensional resistive magnetohydrodynamic (MHD) simulation. The MHD simulation, representing plasmoid formation and ejection through a near-Earth reconnection process, leads to cross-tail electric fields of up to approximately 4 mV/m with integrated voltages across the tail of up to approximately 200 kV. Energization of particles takes place over a wide range along the tail, due to the large spatial extent of the increased electric field together with the finite cross-tail extent of the electric field region. Such accelerated particles appear earthward of the neutral line over a significant portion of the closed field line region inside of the separatrix, not just in the vicinity of the separatrix. Two different acceleration processes are identified: a 'quasi-potential' acceleration, due to particle motion in the direction of the cross-tail electric field, and a 'quasi-betatron' effect, which consists of multiple energy gains from repeated crossings of the acceleration region, mostly on Speiser-type orbits, in the spatially varying induced electric field. The major source region for accelerated particles in the hundreds of keV range is the central plasma sheet at the dawn flank outside the reconnection site. Since this source plasma is already hot and dense, its moderate energization by a factor of approximately 2 may be sufficient to explain the observed increases in the energetic particle fluxes. Particles from the tail are the source of beams at the plasma sheet/lobe boundary. The temporal increase in the energetic particle fluxes, estimated from the increase in energy gain, occurs on a fast timescale of a few minutes, coincident with a strong increase in B(sub z), despite the fact that the inner boundary ('injection boundary') of the distribution of energized particles is fairly smooth.

  18. Self-Consistent Synchrotron Spectra from Trans-Relativistic Electron Acceleration

    NASA Astrophysics Data System (ADS)

    Becker, Peter A.

    2015-01-01

    Most existing analytical models describing the second-order Fermi acceleration of relativistic electrons due to collisions with MHD waves assume that the injected seed particles are already highly relativistic, despite the fact that the most prevalent source of particles is usually the non-relativistic thermal background gas. This presents a problem because the momentum dependence of the momentum diffusion coefficient describing the interaction between the electrons and the MHD waves is qualitatively different in the non-relativistic and highly relativistic limits. The lack of an analytical model has forced workers to rely on numerical simulations to obtain particle spectra describing the trans-relativistic case. In this work, we present the first analytical solution to the global, trans-relativistic problem of electron acceleration, obtained by using a hybrid form for the momentum diffusion coefficient, given by the sum of the two asymptotic forms. We refer to this process as "quasi hard-sphere scattering." The model also incorporates the appropriate momentum dependence for the particle escape timescale, and the effect of synchrotron and inverse-Compton losses, which are critical for establishing the location of the high-energy cutoff in the particle spectrum. Since synchrotron and inverse-Compton losses are included in the transport equation, the resulting radiation spectra are computed self-consistently. The results can be used to model the acceleration of radiating electrons in AGN and solar environments, applications of both types are discussed.

  19. High luminosity operation of the Fermilab accelerator complex

    SciTech Connect

    Shekhar Mishra

    2003-07-15

    Run-II at Fermilab is progressing steadily. In the Run-II scheme, 36 antiproton bunches collide with 36 proton bunches at the CDF and D0 interaction regions in the Tevatron at 980 GeV per beam. The current status and performance of the Fermilab Accelerator complex is reviewed. The plan for Run-II, accelerator upgrades and integration of the Recycler in the accelerator chain will be presented.

  20. 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.

  1. IMPROVING CONSISTENCY OF PERFORMANCE ASSESSMENTS IN THE DOE COMPLEX

    SciTech Connect

    Seitz, R; Elmer Wilhite, E

    2009-01-20

    The low-level waste (LLW) performance assessment (PA) process has been traditionally focused on disposal facilities at a few United States Department of Energy (USDOE) sites and commercial disposal facilities. In recent years, there has been a dramatic increase in the scope of the use of PA-like modeling approaches, involving multiple activities, facilities, contractors and regulators. The scope now includes, for example: (1) National Environmental Policy Act (NEPA) assessments, (2) CERCLA disposal cells, (3) Waste Determinations and High-Level Waste (HLW) Closure activities, (4) Potential on-site disposal of Transuranic (TRU) waste, and (5) In-situ decommissioning (including potential use of existing facilities for disposal). The dramatic increase in the variety of activities requiring more detailed modeling has resulted in a similar increase in the potential for inconsistency in approaches both at a site and complexwide scale. This paper includes a summary of USDOE Environmental Management (EM) sponsored initiatives and activities for improved consistency. New initiatives entitled the Performance Assessment Community of Practice and Performance Assessment Assistance Team are also introduced.

  2. Overcoming complexities for consistent, continental-scale flood mapping

    NASA Astrophysics Data System (ADS)

    Smith, Helen; Zaidman, Maxine; Davison, Charlotte

    2013-04-01

    The EU Floods Directive requires all member states to produce flood hazard maps by 2013. Although flood mapping practices are well developed in Europe, there are huge variations in the scale and resolution of the maps between individual countries. Since extreme flood events are rarely confined to a single country, this is problematic, particularly for the re/insurance industry whose exposures often extend beyond country boundaries. Here, we discuss the challenges of large-scale hydrological and hydraulic modelling, using our experience of developing a 12-country model and set of maps, to illustrate how consistent, high-resolution river flood maps across Europe can be produced. The main challenges addressed include: data acquisition; manipulating the vast quantities of high-resolution data; and computational resources. Our starting point was to develop robust flood-frequency models that are suitable for estimating peak flows for a range of design flood return periods. We used the index flood approach, based on a statistical analysis of historic river flow data pooled on the basis of catchment characteristics. Historical flow data were therefore sourced for each country and collated into a large pan-European database. After a lengthy validation these data were collated into 21 separate analysis zones or regions, grouping smaller river basins according to their physical and climatic characteristics. The very large continental scale basins were each modelled separately on account of their size (e.g. Danube, Elbe, Drava and Rhine). Our methodology allows the design flood hydrograph to be predicted at any point on the river network for a range of return periods. Using JFlow+, JBA's proprietary 2D hydraulic hydrodynamic model, the calculated out-of-bank flows for all watercourses with an upstream drainage area exceeding 50km2 were routed across two different Digital Terrain Models in order to map the extent and depth of floodplain inundation. This generated modelling for

  3. Software Accelerates Computing Time for Complex Math

    NASA Technical Reports Server (NTRS)

    2014-01-01

    Ames Research Center awarded Newark, Delaware-based EM Photonics Inc. SBIR funding to utilize graphic processing unit (GPU) technology- traditionally used for computer video games-to develop high-computing software called CULA. The software gives users the ability to run complex algorithms on personal computers with greater speed. As a result of the NASA collaboration, the number of employees at the company has increased 10 percent.

  4. ACCELERATION IN PERPENDICULAR RELATIVISTIC SHOCKS FOR PLASMAS CONSISTING OF LEPTONS AND HADRONS

    SciTech Connect

    Stockem, A.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.

    2012-08-10

    We investigate the acceleration of light particles in perpendicular shocks for plasmas consisting of a mixture of leptonic and hadronic particles. Starting from the full set of conservation equations for the mixed plasma constituents, we generalize the magnetohydrodynamical jump conditions for a multi-component plasma, including information about the specific adiabatic constants for the different species. The impact of deviations from the standard model of an ideal gas is compared in theory and particle-in-cell simulations, showing that the standard MHD model is a good approximation. The simulations of shocks in electron-positron-ion plasmas are for the first time multi-dimensional, transverse effects are small in this configuration, and one-dimensional (1D) simulations are a good representation if the initial magnetization is chosen high. 1D runs with a mass ratio of 1836 are performed, which identify the Larmor frequency {omega}{sub ci} as the dominant frequency that determines the shock physics in mixed component plasmas. The maximum energy in the non-thermal tail of the particle spectra evolves in time according to a power law {proportional_to}t{sup {alpha}} with {alpha} in the range 1/3 < {alpha} < 1, depending on the initial parameters. A connection is made with transport theoretical models by Drury and Gargate and Spitkovsky, which predict an acceleration time {proportional_to}{gamma} and the theory for small wavelength scattering by Kirk and Reville, which predicts a behavior rather as {proportional_to}{gamma}{sup 2}. Furthermore, we compare different magnetic field orientations with B{sub 0} inside and out of the plane, observing qualitatively different particle spectra than in pure electron-ion shocks.

  5. Neural prediction of complex accelerations for object interception.

    PubMed

    de Rugy, Aymar; Marinovic, Welber; Wallis, Guy

    2012-02-01

    To intercept or avoid moving objects successfully, we must compensate for the sensorimotor delays associated with visual processing and motor movement. Although straightforward in the case of constant velocity motion, it is unclear how humans compensate for accelerations, as our visual system is relatively poor at detecting changes in velocity. Work on free-falling objects suggests that we are able to predict the effects of gravity, but this represents the most simple, limiting case in which acceleration is constant and motion linear. Here, we show that an internal model also predicts the effects of complex, varying accelerations when they result from lawful interactions with the environment. Participants timed their responses with the arrival of a ball rolling within a tube of various shapes. The pattern of errors indicates that participants were able to compensate for most of the effects of the ball acceleration (∼85%) within a relatively short practice (∼300 trials). Errors on catch trials in which the ball velocity was unexpectedly maintained constant further confirmed that participants were expecting the effect of acceleration induced by the shape of the tube. A similar effect was obtained when the visual scene was projected upside down, indicating that the mechanism of this prediction is flexible and not confined to ecologically valid interactions. These findings demonstrate that the brain is able to predict motion on the basis of prior experience of complex interactions between an object and its environment. PMID:22090456

  6. Neural prediction of complex accelerations for object interception.

    PubMed

    de Rugy, Aymar; Marinovic, Welber; Wallis, Guy

    2012-02-01

    To intercept or avoid moving objects successfully, we must compensate for the sensorimotor delays associated with visual processing and motor movement. Although straightforward in the case of constant velocity motion, it is unclear how humans compensate for accelerations, as our visual system is relatively poor at detecting changes in velocity. Work on free-falling objects suggests that we are able to predict the effects of gravity, but this represents the most simple, limiting case in which acceleration is constant and motion linear. Here, we show that an internal model also predicts the effects of complex, varying accelerations when they result from lawful interactions with the environment. Participants timed their responses with the arrival of a ball rolling within a tube of various shapes. The pattern of errors indicates that participants were able to compensate for most of the effects of the ball acceleration (∼85%) within a relatively short practice (∼300 trials). Errors on catch trials in which the ball velocity was unexpectedly maintained constant further confirmed that participants were expecting the effect of acceleration induced by the shape of the tube. A similar effect was obtained when the visual scene was projected upside down, indicating that the mechanism of this prediction is flexible and not confined to ecologically valid interactions. These findings demonstrate that the brain is able to predict motion on the basis of prior experience of complex interactions between an object and its environment.

  7. Electron acceleration and radiation in evolving complex active regions

    NASA Astrophysics Data System (ADS)

    Anastasiadis, A.; Gontikakis, C.; Vilmer, N.; Vlahos, L.

    2004-07-01

    We present a model for the acceleration and radiation of solar energetic particles (electrons) in evolving complex active regions. The spatio - temporal evolution of active regions is calculated using a cellular automaton model, based on self-organized criticality. The acceleration of electrons is due to the presence of randomly placed, localized electric fields produced by the energy release process, simulated by the cellular automaton model. We calculate the resulting kinetic energy distributions of the particles and their emitted X-ray radiation spectra using the thick target approximation, and we perform a parametric study with respect to number of electric fields present and thermal temperature of the injected distribution. Finally, comparing our results with the existing observations, we find that they are in a good agreement with the observed X-ray spectra in the energy range 100-1000 keV.

  8. Accelerating procelain formation by incorporating a complex additive

    SciTech Connect

    Maslennikova, G.N.; Dubovitskii, S.A.; Moroz, I.K.

    1986-05-01

    The authors studied the influence of a complex additive consisting of oxides of calcium, zinc, and magnesium on the formaton of porcelain. In order to achieve a more uniform distribution of the complex additive in the porcelain body it was incorporated in the form of water soluble salts-nitrates, which ensured comparability of results and excluded the effect of the different types of anions. The study of the main parameters of sintering (porosity, shrinkage, and mechanical strength) for the test bodies showed that they sinter at lower temperatures and attain zero porosity, maximum shrinkage, and mechanical strength. The most typical bodies indentified in this way were investigated by methods of complex differential thermal analysis and x-ray diffraction. Thus, the introduction of complex additives consisting of calcium, zinc, and magnesium oxides contributes to the earlier formation of porcelain. With the reduction of firing temperatures by 100/sup 0/C the authors observe an improvement in the basic properties of porcelain.

  9. Elliptic Preconditioner for Accelerating the Self-Consistent Field Iteration in Kohn--Sham Density Functional Theory

    SciTech Connect

    Lin, Lin; Yang, Chao

    2013-10-28

    We discuss techniques for accelerating the self consistent field (SCF) iteration for solving the Kohn-Sham equations. These techniques are all based on constructing approximations to the inverse of the Jacobian associated with a fixed point map satisfied by the total potential. They can be viewed as preconditioners for a fixed point iteration. We point out different requirements for constructing preconditioners for insulating and metallic systems respectively, and discuss how to construct preconditioners to keep the convergence rate of the fixed point iteration independent of the size of the atomistic system. We propose a new preconditioner that can treat insulating and metallic system in a unified way. The new preconditioner, which we call an elliptic preconditioner, is constructed by solving an elliptic partial differential equation. The elliptic preconditioner is shown to be more effective in accelerating the convergence of a fixed point iteration than the existing approaches for large inhomogeneous systems at low temperature.

  10. Dioecy does not consistently accelerate or slow lineage diversification across multiple genera of angiosperms.

    PubMed

    Sabath, Niv; Goldberg, Emma E; Glick, Lior; Einhorn, Moshe; Ashman, Tia-Lynn; Ming, Ray; Otto, Sarah P; Vamosi, Jana C; Mayrose, Itay

    2016-02-01

    Dioecy, the sexual system in which male and female organs are found in separate individuals, allows greater specialization for sex-specific functions and can be advantageous under various ecological and environmental conditions. However, dioecy is rare among flowering plants. Previous studies identified contradictory trends regarding the relative diversification rates of dioecious lineages vs their nondioecious counterparts, depending on the methods and data used. We gathered detailed species-level data for dozens of genera that contain both dioecious and nondioecious species. We then applied a probabilistic approach that accounts for differential speciation, extinction, and transition rates between states to examine whether there is an association between dioecy and lineage diversification. We found a bimodal distribution, whereby dioecious lineages exhibited higher diversification in certain genera but lower diversification in others. Additional analyses did not uncover an ecological or life history trait that could explain a context-dependent effect of dioecy on diversification. Furthermore, in-depth simulations of neutral characters demonstrated that such bimodality is also found when simulating neutral characters across the observed trees. Our analyses suggest that - at least for these genera with the currently available data - dioecy neither consistently places a strong brake on diversification nor is a strong driver.

  11. Dioecy does not consistently accelerate or slow lineage diversification across multiple genera of angiosperms.

    PubMed

    Sabath, Niv; Goldberg, Emma E; Glick, Lior; Einhorn, Moshe; Ashman, Tia-Lynn; Ming, Ray; Otto, Sarah P; Vamosi, Jana C; Mayrose, Itay

    2016-02-01

    Dioecy, the sexual system in which male and female organs are found in separate individuals, allows greater specialization for sex-specific functions and can be advantageous under various ecological and environmental conditions. However, dioecy is rare among flowering plants. Previous studies identified contradictory trends regarding the relative diversification rates of dioecious lineages vs their nondioecious counterparts, depending on the methods and data used. We gathered detailed species-level data for dozens of genera that contain both dioecious and nondioecious species. We then applied a probabilistic approach that accounts for differential speciation, extinction, and transition rates between states to examine whether there is an association between dioecy and lineage diversification. We found a bimodal distribution, whereby dioecious lineages exhibited higher diversification in certain genera but lower diversification in others. Additional analyses did not uncover an ecological or life history trait that could explain a context-dependent effect of dioecy on diversification. Furthermore, in-depth simulations of neutral characters demonstrated that such bimodality is also found when simulating neutral characters across the observed trees. Our analyses suggest that - at least for these genera with the currently available data - dioecy neither consistently places a strong brake on diversification nor is a strong driver. PMID:26467174

  12. Hydrogen pellet acceleration with a two-stage system consisting of a gas gun and a fuseless electromagnetic railgun

    SciTech Connect

    Honig, J.; Kim, K.; Wedge, S.W.

    1986-05-01

    Hydrogen pellets are successfully accelerated for the first time using a two-stage system consisting of a pneumatic gun and an electromagnetic railgun. The pneumatic gun preaccelerator forms cylindrical hydrogen ice pellets (1.6-mm diam x 2.15-mm long) and accelerates them with high-pressure helium gas to velocities in excess of 500 m/s. The booster accelerator, which is a fuseless, circular-bore electromagnetic railgun, derives its propulsive force from a plasma arc armature. The plasma arc armature is formed by electrically breaking down the propellant gas which follows the pellet from the gas gun into the railgun. The diagnostics are for the monitoring of the main capacitor bank and rail currents, for the pellet detection and velocity measurements at the breech and muzzle ends of the railgun, for the recording of the plasma-arc-armature movement inside the railgun bore, and for the photographing of the hydrogen pellet exiting the railgun. Using the system, which is a 60-cm long proof-of-principle machine for refueling magnetic fusion devices, hyrogen pellet velocities exceeding 1 km/s have been achieved for pellets exiting the gas gun at velocities of approx.500 m/s.

  13. Accelerated Biofluid Filling in Complex Microfluidic Networks by Vacuum-Pressure Accelerated Movement (V-PAM).

    PubMed

    Yu, Zeta Tak For; Cheung, Mei Ki; Liu, Shirley Xiaosu; Fu, Jianping

    2016-09-01

    Rapid fluid transport and exchange are critical operations involved in many microfluidic applications. However, conventional mechanisms used for driving fluid transport in microfluidics, such as micropumping and high pressure, can be inaccurate and difficult for implementation for integrated microfluidics containing control components and closed compartments. Here, a technology has been developed termed Vacuum-Pressure Accelerated Movement (V-PAM) capable of significantly enhancing biofluid transport in complex microfluidic environments containing dead-end channels and closed chambers. Operation of the V-PAM entails a pressurized fluid loading into microfluidic channels where gas confined inside can rapidly be dissipated through permeation through a thin, gas-permeable membrane sandwiched between microfluidic channels and a network of vacuum channels. Effects of different structural and operational parameters of the V-PAM for promoting fluid filling in microfluidic environments have been studied systematically. This work further demonstrates the applicability of V-PAM for rapid filling of temperature-sensitive hydrogels and unprocessed whole blood into complex irregular microfluidic networks such as microfluidic leaf venation patterns and blood circulatory systems. Together, the V-PAM technology provides a promising generic microfluidic tool for advanced fluid control and transport in integrated microfluidics for different microfluidic diagnosis, organs-on-chips, and biomimetic studies. PMID:27409528

  14. Using complex networks to quantify consistency in the use of words

    NASA Astrophysics Data System (ADS)

    Amancio, D. R.; Oliveira, O. N., Jr.; Costa, L. da F.

    2012-01-01

    In this paper we have quantified the consistency of word usage in written texts represented by complex networks, where words were taken as nodes, by measuring the degree of preservation of the node neighborhood. Words were considered highly consistent if the authors used them with the same neighborhood. When ranked according to the consistency of use, the words obeyed a log-normal distribution, in contrast to Zipf's law that applies to the frequency of use. Consistency correlated positively with the familiarity and frequency of use, and negatively with ambiguity and age of acquisition. An inspection of some highly consistent words confirmed that they are used in very limited semantic contexts. A comparison of consistency indices for eight authors indicated that these indices may be employed for author recognition. Indeed, as expected, authors of novels could be distinguished from those who wrote scientific texts. Our analysis demonstrated the suitability of the consistency indices, which can now be applied in other tasks, such as emotion recognition.

  15. Investigation of electron-atom/molecule scattering resonances: Two complex multiconfigurational self-consistent field approaches

    SciTech Connect

    Samanta, Kousik; Yeager, Danny L.

    2015-01-22

    Resonances are temporarily bound states which lie in the continuum part of the Hamiltonian. If the electronic coordinates of the Hamiltonian are scaled (“dilated”) by a complex parameter, η = αe{sup iθ} (α, θ real), then its complex eigenvalues represent the scattering states (resonant and non-resonant) while the eigenvalues corresponding to the bound states and the ionization and the excitation thresholds remain real and unmodified. These make the study of these transient species amenable to the bound state methods. We developed a quadratically convergent multiconfigurational self-consistent field method (MCSCF), a well-established bound-state technique, combined with a dilated Hamiltonian to investigate resonances. This is made possible by the adoption of a second quantization algebra suitable for a set of “complex conjugate biorthonormal” spin orbitals and a modified step-length constraining algorithm to control the walk on the complex energy hypersurface while searching for the stationary point using a multidimensional Newton-Raphson scheme. We present our computational results for the {sup 2}PBe{sup −} shape resonances using two different computationally efficient methods that utilize complex scaled MCSCF (i.e., CMCSCF). These two methods are to straightforwardly use CMCSCF energy differences and to obtain energy differences using an approximation to the complex multiconfigurational electron propagator. It is found that, differing from previous computational studies by others, there are actually two {sup 2}PBe{sup −} shape resonances very close in energy. In addition, N{sub 2} resonances are examined using one of these methods.

  16. Supramolecular Complex Antioxidant Consisting of Vitamins C, E and Hydrophilic-Hydrophobic Silica Nanoparticles

    NASA Astrophysics Data System (ADS)

    Laguta, I. V.; Kuzema, P. O.; Stavinskaya, O. N.; Kazakova, O. A.

    Samples with varied amount of surface trimethylsilyl groups were obtained via gas-phase chemical modification of silica nanoparticles. The biocompatibility tests conducted in erythrocyte suspension have shown that hydrophobization of silica decreases its damaging effect to the cells. Being wettable in aqueous media, partially silylated silicas have higher affinity to hydrophobic bioactive molecules in comparison with the initial silica. Novel antioxidant consisting of vitamins C and E and silica with 40% of surface trimethylsilyl groups was formulated. It was found that supramolecular complexes are formed on the silica surface due to the affinity of water- and fat-soluble antioxidants to hydrophilic silanol and hydrophobic trimethylsilyl groups, respectively. Test reactions (total phenolic index determination, DPPH test) and in vitro studies (spectral analysis of erythrocyte suspensions undergoing UV irradiation) revealed the correlation between antioxidant activity of the complex antioxidant and the vitamins’ content. The antioxidant remained active during long-term storage under standard conditions.

  17. Supramolecular Complex Antioxidant Consisting of Vitamins C, E and Hydrophilic-Hydrophobic Silica Nanoparticles

    NASA Astrophysics Data System (ADS)

    Laguta, I. V.; Kuzema, P. O.; Stavinskaya, O. N.; Kazakova, O. A.

    Samples with varied amount of surface trimethylsilyl groups were obtained via gas-phase chemical modification of silica nanoparticles. The biocompatibility tests conducted in erythrocyte suspension have shown that hydrophobization of silica decreases its damaging effect to the cells. Being wettable in aqueous media, partially silylated silicas have higher affinity to hydrophobic bioactive molecules in comparison with the initial silica. Novel antioxidant consisting of vitamins C and E and silica with 40% of surface trimethylsilyl groups was formulated. It was found that supramolecular complexes are formed on the silica surface due to the affinity of water- and fat-soluble antioxidants to hydrophilic silanol and hydrophobic trimethylsilyl groups, respectively. Test reactions (total phenolic index determination, DPPH test) and in vitro studies (spectral analysis of erythrocyte suspensions undergoing UV irradiation) revealed the correlation between antioxidant activity of the complex antioxidant and the vitamins' content. The antioxidant remained active during long-term storage under standard conditions.

  18. Quantifying the Consistency of Wearable Knee Acoustical Emission Measurements During Complex Motions.

    PubMed

    Toreyin, Hakan; Jeong, Hyeon Ki; Hersek, Sinan; Teague, Caitlin N; Inan, Omer T

    2016-09-01

    Knee-joint sounds could potentially be used to noninvasively probe the physical and/or physiological changes in the knee associated with rehabilitation following acute injury. In this paper, a system and methods for investigating the consistency of knee-joint sounds during complex motions in silent and loud background settings are presented. The wearable hardware component of the system consists of a microelectromechanical systems microphone and inertial rate sensors interfaced with a field programmable gate array-based real-time processor to capture knee-joint sound and angle information during three types of motion: flexion-extension (FE), sit-to-stand (SS), and walking (W) tasks. The data were post-processed to extract high-frequency and short-duration joint sounds (clicks) with particular waveform signatures. Such clicks were extracted in the presence of three different sources of interference: background, stepping, and rubbing noise. A histogram-vector Vn(→) was generated from the clicks in a motion-cycle n, where the bin range was 10°. The Euclidean distance between a vector and the arithmetic mean Vav(→) of all vectors in a recording normalized by the Vav(→) is used as a consistency metric dn. Measurements from eight healthy subjects performing FE, SS, and W show that the mean (of mean) consistency metric for all subjects during SS (μ [ μ (dn)] = 0.72 in silent, 0.85 in loud) is smaller compared with the FE (μ [ μ (dn)] = 1.02 in silent, 0.95 in loud) and W ( μ [ μ (dn)] = 0.94 in silent, 0.97 in loud) exercises, thereby implying more consistent click-generation during SS compared with the FE and W. Knee-joint sounds from one subject performing FE during five consecutive work-days (μ [ μ (dn) = 0.72) and five different times of a day (μ [ μ (dn) = 0.73) suggests high consistency of the clicks on different days and throughout a day. This work represents the first time, to the best of our knowledge, that joint sound consistency has been

  19. High intensity proton operation at the Brookhaven AGS accelerator complex

    SciTech Connect

    Ahrens, L.A.; Blaskiewicz, M.; Bleser, E.; Brennan, J.M.; Gardner, C.; Glenn, J.W.; Onillon, E.; Reece, R.K.; Roser, T.; Soukas, A.

    1994-08-01

    With the completion of the AGS rf upgrade, and the implementation of a transition {open_quotes}jump{close_quotes}, all of accelerator systems were in place in 1994 to allow acceleration of the proton intensity available from the AGS Booster injector to AGS extraction energy and delivery to the high energy users. Beam commissioning results with these new systems are presented. Progress in identifying and overcoming other obstacles to higher intensity are given. These include a careful exploration of the stopband strengths present on the AGS injection magnetic porch, and implementation of the AGS single bunch transverse dampers throughout the acceleration cycle.

  20. A magnetohydrodynamic model of the M87 jet. II. Self-consistent quad-shock jet model for optical relativistic motions and particle acceleration

    SciTech Connect

    Nakamura, Masanori

    2014-04-20

    We describe a new paradigm for understanding both relativistic motions and particle acceleration in the M87 jet: a magnetically dominated relativistic flow that naturally produces four relativistic magnetohydrodynamic (MHD) shocks (forward/reverse fast and slow modes). We apply this model to a set of optical super- and subluminal motions discovered by Biretta and coworkers with the Hubble Space Telescope during 1994-1998. The model concept consists of ejection of a single relativistic Poynting jet, which possesses a coherent helical (poloidal + toroidal) magnetic component, at the remarkably flaring point HST-1. We are able to reproduce quantitatively proper motions of components seen in the optical observations of HST-1 with the same model we used previously to describe similar features in radio very long baseline interferometry observations in 2005-2006. This indicates that the quad relativistic MHD shock model can be applied generally to recurring pairs of super/subluminal knots ejected from the upstream edge of the HST-1 complex as observed from radio to optical wavelengths, with forward/reverse fast-mode MHD shocks then responsible for observed moving features. Moreover, we identify such intrinsic properties as the shock compression ratio, degree of magnetization, and magnetic obliquity and show that they are suitable to mediate diffusive shock acceleration of relativistic particles via the first-order Fermi process. We suggest that relativistic MHD shocks in Poynting-flux-dominated helical jets may play a role in explaining observed emission and proper motions in many active galactic nuclei.

  1. Progress Towards Doubling the Beam Power at Fermilab's Accelerator Complex

    SciTech Connect

    Kourbanis, ioanis

    2014-06-01

    After a 14 month shutdown accelerator modifications and upgrades are in place to allow us doubling of the Main Injector beam power. We will discuss the past MI high power operation and the current progress towards doubling the power.

  2. Consistency between molecular phylogeny and morphological classification of the Salix matsudana Koidz. complex (Salicaceae).

    PubMed

    Du, S H; Wang, Z S; Li, Y X; Wang, D S; Zhang, J G

    2015-07-31

    The morphological species concept is based on morpho-logical traits, which are often subject to subjectivity or artifact. Molecular evidence is needed to test the reliability of morphological classification of taxa that are controversial and to provide appropriate taxonomic de-limitation. In this study, we used 15 single-copy nuclear loci and 2 chloroplast fragments to verify the morphological classification of the Salix matsudana Koidz. complex using phylogenetic approaches. Complete sequence alignment showed slight diversification in nuclear sequences and no variety in chloroplast DNA fragments. Phylogenetic trees revealed a monophyletic group consisting of all individuals of S. matsudana and 2 clades within this group, with a 100% bootstrap support value and 1.00 posterior probability. The topology of the phylogenetic trees was highly consistent with the morphological classification of the S. matsudana complex. Verifying the genetic background of these classification units based on remarkable morphological differences will provide a foundation for future studies of Salix and the breeding of new horticultural varieties.

  3. Consistent global structures of complex RNA states through multidimensional chemical mapping.

    PubMed

    Cheng, Clarence Yu; Chou, Fang-Chieh; Kladwang, Wipapat; Tian, Siqi; Cordero, Pablo; Das, Rhiju

    2015-06-02

    Accelerating discoveries of non-coding RNA (ncRNA) in myriad biological processes pose major challenges to structural and functional analysis. Despite progress in secondary structure modeling, high-throughput methods have generally failed to determine ncRNA tertiary structures, even at the 1-nm resolution that enables visualization of how helices and functional motifs are positioned in three dimensions. We report that integrating a new method called MOHCA-seq (Multiplexed •OH Cleavage Analysis with paired-end sequencing) with mutate-and-map secondary structure inference guides Rosetta 3D modeling to consistent 1-nm accuracy for intricately folded ncRNAs with lengths up to 188 nucleotides, including a blind RNA-puzzle challenge, the lariat-capping ribozyme. This multidimensional chemical mapping (MCM) pipeline resolves unexpected tertiary proximities for cyclic-di-GMP, glycine, and adenosylcobalamin riboswitch aptamers without their ligands and a loose structure for the recently discovered human HoxA9D internal ribosome entry site regulon. MCM offers a sequencing-based route to uncovering ncRNA 3D structure, applicable to functionally important but potentially heterogeneous states.

  4. Consistent global structures of complex RNA states through multidimensional chemical mapping

    PubMed Central

    Cheng, Clarence Yu; Chou, Fang-Chieh; Kladwang, Wipapat; Tian, Siqi; Cordero, Pablo; Das, Rhiju

    2015-01-01

    Accelerating discoveries of non-coding RNA (ncRNA) in myriad biological processes pose major challenges to structural and functional analysis. Despite progress in secondary structure modeling, high-throughput methods have generally failed to determine ncRNA tertiary structures, even at the 1-nm resolution that enables visualization of how helices and functional motifs are positioned in three dimensions. We report that integrating a new method called MOHCA-seq (Multiplexed •OH Cleavage Analysis with paired-end sequencing) with mutate-and-map secondary structure inference guides Rosetta 3D modeling to consistent 1-nm accuracy for intricately folded ncRNAs with lengths up to 188 nucleotides, including a blind RNA-puzzle challenge, the lariat-capping ribozyme. This multidimensional chemical mapping (MCM) pipeline resolves unexpected tertiary proximities for cyclic-di-GMP, glycine, and adenosylcobalamin riboswitch aptamers without their ligands and a loose structure for the recently discovered human HoxA9D internal ribosome entry site regulon. MCM offers a sequencing-based route to uncovering ncRNA 3D structure, applicable to functionally important but potentially heterogeneous states. DOI: http://dx.doi.org/10.7554/eLife.07600.001 PMID:26035425

  5. Pharmacological evidence is consistent with a prominent role of spatial memory in complex navigation.

    PubMed

    Roth, Timothy C; Krochmal, Aaron R

    2016-02-10

    The ability to learn about the spatial environment plays an important role in navigation, migration, dispersal, and foraging. However, our understanding of both the role of cognition in the development of navigation strategies and the mechanisms underlying these strategies is limited. We tested the hypothesis that complex navigation is facilitated by spatial memory in a population of Chrysemys picta that navigate with extreme precision (±3.5 m) using specific routes that must be learned prior to age three. We used scopolamine, a muscarinic acetylcholine receptor antagonist, to manipulate the cognitive spatial abilities of free-living turtles during naturally occurring overland movements. Experienced adults treated with scopolamine diverted markedly from their precise navigation routes. Naive juveniles lacking experience (and memory) were not affected by scopolamine, and thereby served as controls for perceptual or non-spatial cognitive processes associated with navigation. Further, neither adult nor juvenile movement was affected by methylscopolamine, a form of scopolamine that does not cross the blood-brain barrier, a control for the peripheral effects of scopolamine. Together, these results are consistent with a role of spatial cognition in complex navigation and highlight a cellular mechanism that might underlie spatial cognition. Overall, our findings expand our understanding of the development of complex cognitive abilities of vertebrates and the neurological mechanisms of navigation.

  6. Self-consistent continuum solvation for optical absorption of complex molecular systems in solution

    SciTech Connect

    Timrov, Iurii; Biancardi, Alessandro; Andreussi, Oliviero; Marzari, Nicola; Baroni, Stefano

    2015-01-21

    We introduce a new method to compute the optical absorption spectra of complex molecular systems in solution, based on the Liouville approach to time-dependent density-functional perturbation theory and the revised self-consistent continuum solvation model. The former allows one to obtain the absorption spectrum over a whole wide frequency range, using a recently proposed Lanczos-based technique, or selected excitation energies, using the Casida equation, without having to ever compute any unoccupied molecular orbitals. The latter is conceptually similar to the polarizable continuum model and offers the further advantages of allowing an easy computation of atomic forces via the Hellmann-Feynman theorem and a ready implementation in periodic-boundary conditions. The new method has been implemented using pseudopotentials and plane-wave basis sets, benchmarked against polarizable continuum model calculations on 4-aminophthalimide, alizarin, and cyanin and made available through the QUANTUM ESPRESSO distribution of open-source codes.

  7. Dynamic Self-Consistent Field Theory of Inhomogeneous Complex Fluids Under Shear

    NASA Astrophysics Data System (ADS)

    Mihajlovic, Maja; Lo, Tak Shing; Shnidman, Yitzhak

    2003-03-01

    Understanding and predicting the interplay between morphology and rheology of sheared, inhomogeneous, complex fluids is of great importance. Yet modeling of such phenomena is in its infancy. We have developed a novel dynamic self-consistent field (DSCF) theory that makes possible detailed computational study of such phenomena. Our DSCF theory couples the time evolution of chain conformation statistics with probabilistic transport equations for volume fractions and momenta, based on local conservation laws formulated on a segmental scale. To generate chain conformation statistics, we are using a modification of the lattice random walk formalism of Scheutjens and Fleer. Their static SCF theory is limited to equilibrium systems, since probability distributions are obtained by free energy minimization, assuming isotropic Gaussian chain conformations. In contrast, our DSCF approach accounts for explicit time evolution of the segmental and (anisotropic) stepping probabilities used for generating chain conformations. We will present highlights of DSCF studies of a variety of inhomogenous fluids containing homopolymers, block copolymers and nanoparticles.

  8. Self-consistent continuum solvation for optical absorption of complex molecular systems in solution.

    PubMed

    Timrov, Iurii; Andreussi, Oliviero; Biancardi, Alessandro; Marzari, Nicola; Baroni, Stefano

    2015-01-21

    We introduce a new method to compute the optical absorption spectra of complex molecular systems in solution, based on the Liouville approach to time-dependent density-functional perturbation theory and the revised self-consistent continuum solvation model. The former allows one to obtain the absorption spectrum over a whole wide frequency range, using a recently proposed Lanczos-based technique, or selected excitation energies, using the Casida equation, without having to ever compute any unoccupied molecular orbitals. The latter is conceptually similar to the polarizable continuum model and offers the further advantages of allowing an easy computation of atomic forces via the Hellmann-Feynman theorem and a ready implementation in periodic-boundary conditions. The new method has been implemented using pseudopotentials and plane-wave basis sets, benchmarked against polarizable continuum model calculations on 4-aminophthalimide, alizarin, and cyanin and made available through the Quantum ESPRESSO distribution of open-source codes. PMID:25612693

  9. Accelerating the Computation of Detailed Chemical Reaction Kinetics for Simulating Combustion of Complex Fuels

    SciTech Connect

    Grout, Ray W

    2012-01-01

    Combustion of hydrocarbon fuels has been a very challenging scientific and engineering problem due to the complexity of turbulent flows and hydrocarbon reaction kinetics. There is an urgent need to develop an efficient modeling capability to accurately predict the combustion of complex fuels. Detailed chemical kinetic models for the surrogates of fuels such as gasoline, diesel and JP-8 consist of thousands of chemical species and Arrhenius reaction steps. Oxygenated fuels such as bio-fuels and heavier hydrocarbons, such as from newer fossil fuel sources, are expected to have a much more complex chemistry requiring increasingly larger chemical kinetic models. Such models are beyond current computational capability, except for homogeneous or partially stirred reactor type calculations. The advent of highly parallel multi-core processors and graphical processing units (GPUs) promises a steep increase in computational performance in the coming years. This paper will present a software framework that translates the detailed chemical kinetic models to high- performance code targeted for GPU accelerators.

  10. Analysis of complex cardiovascular flow with three-component acceleration-encoded MRI.

    PubMed

    Barker, Alex J; Staehle, Felix; Bock, Jelena; Jung, Bernd A; Markl, Michael

    2012-01-01

    Functional information regarding cardiac performance, pressure gradients, and local flow derangement are available from blood acceleration fields. Thus, this study examines a 2D and 3D phase contrast sequence optimized to efficiently encode three-directional, time-resolved acceleration in vitro and in vivo. Stenosis phantom acceleration measurements were compared to acceleration derived from standard velocity encoded phase contrast-magnetic resonance imaging (i.e., "velocity-derived acceleration"). For in vivo analysis, three-directional 2D acceleration maps were compared to velocity-derived acceleration using regions proximal and distal to the aortic valve in six healthy volunteers at 1.5 and 3.0 T (voxel size = 1.4 × 2.1 × 8 mm, temporal resolution = 16-20 ms). In addition, a 4D acceleration sequence was evaluated for feasibility in a healthy volunteer and postrepair biscuspid aortic valve patient with an ascending aortic aneurysm. The phantom magnetic resonance acceleration measurements were more accurate (nonturbulent root mean square error = 2.2 vs. 5.1 m/s(2) for phase contrast-magnetic resonance imaging) and 10 times less noisy (nonturbulent σ = 0.9 vs. 13.6 m/s(2) for phase contrast-magnetic resonance imaging) than velocity-derived acceleration. Acceleration mapping of the left ventricular outflow tract and aortic arch exhibited signal voids colocated with complex flow events such as vortex formation and high order motion. 4D acceleration data, visualized in combination with the velocity data, may provide new insight into complex flow phenomena.

  11. Stochastic modelling of spatially and temporally consistent daily precipitation time-series over complex topography

    NASA Astrophysics Data System (ADS)

    Keller, Denise E.; Fischer, Andreas M.; Frei, Christoph; Liniger, Mark A.; Appenzeller, Christof; Knutti, Reto

    2014-05-01

    There is a growing demand for high-resolution precipitation time-series at the local scale that are both consistent in time and in space. This is of high relevance for climate impact models that are sensitive to averaged rainfall amount over a specific region and over a multi-day period (e.g. for modeling river runoff regimes). In this regard, weather generators (WGs) calibrated at multiple sites, are an appealing technique that allow the simulation of synthetic series of unlimited length taking into account the spatio-temporal correlation structure. To date, only a few multi-site WGs have been documented in the literature and those that exist have rarely been tested for a topography as complex as the Alps. It is the aim of this study to fill this gap. Here, we present results from multi-site precipitation simulations with a generator that has been inspired by Wilks (1998). In essence, it is a Richardson-type WG that additionally takes into account the spatial correlation structure between all the station pairs. A first-order two-state Markov process is chosen to simulate daily precipitation occurrences, while precipitation amounts are re-sampled from a mixture model of two exponential distributions fitted at individual stations. Our multi-site WG is tested and evaluated here at the example of the hydrological catchment "Thur" in the Swiss Alps for the time-period 1961-2011 and on a monthly basis. In the catchment eight meteorological stations (from MeteoSwiss) are considered at which artificial time-series with the respective spatio-temporal dependence structure are simulated. The eight measurement sites are evenly distributed over the catchment, representing the complex topographical and associated precipitation characteristics. The study reveals first that our stochastic model is able to generate time-series that well represent the annual cycle of the precipitation statistics, such as mean wet day frequency and intensity as well as accumulated precipitation

  12. The operation of the LHC accelerator complex (2/2)

    ScienceCinema

    None

    2016-07-12

    These lectures will give an overview of what happens when the LHC is in running mode. They are aimed at students working on the LHC experiments, but all those who are curious about what happens behind the scenes of the LHC are welcomed. You will learn all you always wanted to know about the LHC, and never had the courage to ask! The only pre-requisite is a basic, college-level, knowledge of EM and of the principles that allow to steer charged beams. Topics covered will include, among others: - the description of the injector chain, from the generation of the protons, to the delivery of bunches to the LHC. - the discussion of the steps required to accelerate the beams in the LHC, to bring them into collision, and to control the luminosity at the interaction points. - the description of the monitoring tools available to the LHC operators, and an explanation of the various plots and panels that can be found on the LHC web pages. o Lecture 1: Wednesday April 7, 10-11am o Lecture 2: Friday April 9, 10-11am The lectures will be webcast, recorded and archived. Coffee will be served before the lectures, starting at 9:45

  13. The operation of the LHC accelerator complex (1/2)

    ScienceCinema

    None

    2016-07-12

    These lectures will give an overview of what happens when the LHC is in running mode. They are aimed at students working on the LHC experiments, but all those who are curious about what happens behind the scenes of the LHC are welcomed. You will learn all you always wanted to know about the LHC, and never had the courage to ask! The only pre-requisite is a basic, college-level, knowledge of EM and of the principles that allow to steer charged beams. Topics covered will include, among others: - the description of the injector chain, from the generation of the protons, to the delivery of bunches to the LHC. - the discussion of the steps required to accelerate the beams in the LHC, to bring them into collision, and to control the luminosity at the interaction points. - the description of the monitoring tools available to the LHC operators, and an explanation of the various plots and panels that can be found on the LHC web pages. o Lecture 1: Wednesday April 7, 10-11am o Lecture 2: Friday April 9, 10-11am The lectures will be webcast, recorded and archived. Coffee will be served before the lectures, starting at 9:45

  14. The operation of the LHC accelerator complex (1/2)

    SciTech Connect

    2010-04-07

    These lectures will give an overview of what happens when the LHC is in running mode. They are aimed at students working on the LHC experiments, but all those who are curious about what happens behind the scenes of the LHC are welcomed. You will learn all you always wanted to know about the LHC, and never had the courage to ask! The only pre-requisite is a basic, college-level, knowledge of EM and of the principles that allow to steer charged beams. Topics covered will include, among others: - the description of the injector chain, from the generation of the protons, to the delivery of bunches to the LHC. - the discussion of the steps required to accelerate the beams in the LHC, to bring them into collision, and to control the luminosity at the interaction points. - the description of the monitoring tools available to the LHC operators, and an explanation of the various plots and panels that can be found on the LHC web pages. o Lecture 1: Wednesday April 7, 10-11am o Lecture 2: Friday April 9, 10-11am The lectures will be webcast, recorded and archived. Coffee will be served before the lectures, starting at 9:45

  15. The operation of the LHC accelerator complex (2/2)

    SciTech Connect

    2010-04-09

    These lectures will give an overview of what happens when the LHC is in running mode. They are aimed at students working on the LHC experiments, but all those who are curious about what happens behind the scenes of the LHC are welcomed. You will learn all you always wanted to know about the LHC, and never had the courage to ask! The only pre-requisite is a basic, college-level, knowledge of EM and of the principles that allow to steer charged beams. Topics covered will include, among others: - the description of the injector chain, from the generation of the protons, to the delivery of bunches to the LHC. - the discussion of the steps required to accelerate the beams in the LHC, to bring them into collision, and to control the luminosity at the interaction points. - the description of the monitoring tools available to the LHC operators, and an explanation of the various plots and panels that can be found on the LHC web pages. o Lecture 1: Wednesday April 7, 10-11am o Lecture 2: Friday April 9, 10-11am The lectures will be webcast, recorded and archived. Coffee will be served before the lectures, starting at 9:45

  16. Dynamic self-consistent field theory of inhomogeneous complex fluids under shear

    NASA Astrophysics Data System (ADS)

    Mihajlovic, Maja Lazar

    Understanding and predicting the interplay between morphology and rheology of sheared, inhomogeneous, complex fluids is of great importance. Yet the modeling of such phenomena is in its infancy. We have developed a novel dynamic self-consistent field (DSCF) theory that makes possible a detailed computational study of such phenomena. Our DSCF theory couples the time evolution of chain conformation statistics with probabilistic transport equations for volume fractions and momenta, based on local conservation laws formulated on a segmental scale. To generate chain conformation statistics, we are using a modification of the lattice random walk formalism of Scheutjens and Fleer. Their static SCF theory is limited to equilibrium systems, since probability distributions are obtained by free energy minimization, assuming isotropic Gaussian chain conformations. In contrast, our DSCF approach accounts for explicit time evolution of the segmental and (anisotropic) conditional stepping probabilities used for generating chain conformations. We have applied the DSCF model to a variety of isothermal inhomogenous fluids containing homopolymers, block copolymers and colloidal particles. In all the simulations, the system is equilibrated before the onset of a steady shear at the walls. Our results suggest that, on short time scales, the velocity evolution resembles shock wave propagation. In the course of time, the amplitude of the shock waves is viscously damped, giving rise to a Couette-like steady state velocity profile. This is also reflected in the temporal evolution of the tensor of the second moment of the end-to-end vector and the dissipative stress tensor. The two- and three-component polymer blends (with a diblock copolymer as the third component) exhibit the interfacial velocity and viscosity slip. The addition of a diblock copolymer suppresses the velocity, and therefore the viscosity slip. Colloidal particles suspended in a simple fluid exhibit layering near the walls

  17. Studies of a colorimetric array consisted of metalloporphrins and Pt complexes

    NASA Astrophysics Data System (ADS)

    Luo, Jing; Ma, Tengshuang; Li, Lu; Pan, Pinghua; Xu, Jianhua; Jiang, Yadong; Yang, Yajie

    2010-10-01

    We have studied the absorption of volatile organic compounds (VOCs) and vapochromic characterization by a colorimetric array based on metalloporphyrins and Pt complexes: ZnTPP, CuTPP, and [Pt(Me2bizmpy)Cl]Cl (TPP=tetraphenylporphrins; Me2bzimpy=2,6-bis(N-methylbenzimidazol-2-yl)pyridine). The array was exposed to pyridine, tetrahydrofuran, ethyl acetate, methanol and acetonitrile. The experimental results demonstrate that the Pt complexes are sensitive to methanol and acetonitrile, while ZnTPP and CuTPP present an obvious response to pyridine, tetrahydrofuran and ethyl acetate. The response behaviors are reversible and rapid within seconds. The changes of Ultra Violet Visible (UV-visible) absorption spectrums of ZnTPP and CuTPP LB films before and after exposure upon the VOCs are also discussed. In addition, the differences of absorption spectrum of Pt complexes dissolved in several solvents are mentioned. The results show that [Pt(Me2bizmpy)Cl]Cl, CuTPP and ZnTPP exhibit reversible changes of action with VOCs, and they show promising future to be used in Smell-Seeing Electronic Nose to identify VOCs.

  18. β-Cyclodextrin as a Metal-anionic Porphyrin Complexation Accelerator in Aqueous Media.

    PubMed

    Ohtomo, Takao; Yokoyama, Aya; Konno, Mitsuyuki; Ohno, Osamu; Igarashi, Shukuro; Takagai, Yoshitaka

    2016-01-01

    The rate of the complexation reaction between anionic porphyrins and 11 metal ions was found to be accelerated by the presence of β-cyclodextrin (β-CD) in aqueous media at room temperature without the need for additional heating or sonication. The porphyrin complexation reaction with metal ions under aqueous conditions can be difficult due to the strong hydration energy between the metal ions and water. In this study, the specific role of β-CD as an accelerator was determined and found to enhance the typically slow reaction of the porphyrin with metal ions. A significant acceleration effect was exhibited when the model anionic porphyrin, 5,10,15,20-tetraphenyl-21H,23H-porphine-tetrasulfonic acid, and Pb(II) ions were combined in the presence of β-CD. Other than for Hg ion, the addition of β-CD decreased the metalation reaction time from 30 to 2 min. The order in the degree of acceleration was Pb > Zn, Cd > Cu > Fe, Pd > Sn > Ag, Co, Mn. Using Pb(II) as the model ion, it was determined that the complexation rate constant was enhanced by a factor of 2.4, while the dissociation rate constant was diminished by a factor of 135 in the presence of added β-CD relative to that in its absence. Overall, the complex was much more stable (formation equilibrium constant 324-fold greater in the β-CD medium. The formation of a ternary complex (cf. bicapped complex; (β-CD)2-porphyrin-metal ion) was demonstrated through the use of nuclear magnetic-resonance spectroscopy and mass spectrometry. This acceleration effect is expected to be applicable systems in which porphyrin ligands are employed for determining of metal ions in chemical analysis and separation science. PMID:27302582

  19. β-Cyclodextrin as a Metal-anionic Porphyrin Complexation Accelerator in Aqueous Media.

    PubMed

    Ohtomo, Takao; Yokoyama, Aya; Konno, Mitsuyuki; Ohno, Osamu; Igarashi, Shukuro; Takagai, Yoshitaka

    2016-01-01

    The rate of the complexation reaction between anionic porphyrins and 11 metal ions was found to be accelerated by the presence of β-cyclodextrin (β-CD) in aqueous media at room temperature without the need for additional heating or sonication. The porphyrin complexation reaction with metal ions under aqueous conditions can be difficult due to the strong hydration energy between the metal ions and water. In this study, the specific role of β-CD as an accelerator was determined and found to enhance the typically slow reaction of the porphyrin with metal ions. A significant acceleration effect was exhibited when the model anionic porphyrin, 5,10,15,20-tetraphenyl-21H,23H-porphine-tetrasulfonic acid, and Pb(II) ions were combined in the presence of β-CD. Other than for Hg ion, the addition of β-CD decreased the metalation reaction time from 30 to 2 min. The order in the degree of acceleration was Pb > Zn, Cd > Cu > Fe, Pd > Sn > Ag, Co, Mn. Using Pb(II) as the model ion, it was determined that the complexation rate constant was enhanced by a factor of 2.4, while the dissociation rate constant was diminished by a factor of 135 in the presence of added β-CD relative to that in its absence. Overall, the complex was much more stable (formation equilibrium constant 324-fold greater in the β-CD medium. The formation of a ternary complex (cf. bicapped complex; (β-CD)2-porphyrin-metal ion) was demonstrated through the use of nuclear magnetic-resonance spectroscopy and mass spectrometry. This acceleration effect is expected to be applicable systems in which porphyrin ligands are employed for determining of metal ions in chemical analysis and separation science.

  20. Future Development Of The Flerov Laboratory Accelerator Complex (Project DRIBs-III)

    NASA Astrophysics Data System (ADS)

    Gulbekian, G. G.; Dmitriev, S. N.; Itkis, M. G.; Oganessian, Yu. Ts.; Popeko, A. G.

    2010-04-01

    Future development of the FLNR accelerator complex (project DRIBs-III) includes modernization of existing cyclotrons, construction of a new experimental hall, creation of a new high current cyclotron and of next generation experimental set-ups. Realization of the project is planned for 2010-2016.

  1. Chirality of ordered molecular complexes consisting of protein with fixed prosthetic group

    NASA Astrophysics Data System (ADS)

    Pancoska, Petr; Bednarova, Lucie; Kapsa, Vojtech

    1992-04-01

    The changes of properties of an achiral prosthetic group upon its fixation on the chiral molecular matrix are discussed using the concept of chirality. We analyze the difference Δ< overlineA> = < overlineA> R - < overlineA> L in the expectation values of an operator describing the change of the prosthetic group property when it is bonded in two orientations, enatiomorphous with respect to the chiral molecular matrix. The wavefunctions of Barron and a density matrix formalism are used to show that Δ< overlineA> is nonzero for both parity odd and even observables, thus distinguishing molecular complexes from enantiomeric species. The examples demonstrate the interconnection of Δ< overlineA> with the energetics of interaction between the matrix and the prosthetic group.

  2. Complex step derivative approximation of consistent tangent operators for viscoelasticity based on fractional calculus

    NASA Astrophysics Data System (ADS)

    Hürkamp, André; Tanaka, Masato; Kaliske, Michael

    2015-12-01

    In this contribution, the convergence behaviour of simulations with nonlinear viscoelastic models for rubber-like materials using fractional derivatives is investigated. Based on the complex step derivative approximation, numerical approximation schemes for tangent operators on the local and global algorithmic level are analysed. Material models including fractional derivatives usually exhibit numerical difficulties, since the entire stress history of the material has to be considered for the current stress state. Non-classical methods can help to reduce the numerical effort, but the convergence behaviour is not perfect. In this paper, a classical and a non-classical fractional element based viscoelastic material formulation are analysed. The local and the global convergence rate using analytically and numerically derived tangents are investigated and compared to the convergence behaviour of a standard nonlinear viscoelastic model. Numerical examples on rubber materials are exploited, showing the performance of the proposed methods. It can be proven that the outlined numerical differentiation schemes improve the convergence rate, as well as reduce the computation time for the fractional element based material models.

  3. Complex System for Ground-Based and Accelerated Simulation of Six Extremal Space Factors (KIFK)

    NASA Astrophysics Data System (ADS)

    Abraimov, V. V.; Kolybaev, L. K.; Verkhovtseva, E. T.; Nekludov, I. M.; Rybalko, V. F.; Borts, B. V.

    This work was aimed at 1. Development and construction of a complex SF simulator for simultaneous and accelerated simulation of six SF (unparalleled in the GUS and ESA countries): artificial Sun radiation (200..2500 nm) + VUV radiation (5..200 nm) + proton (p+) and electron (e-) radiation (50..200 keV) + vacuum (10-6 Torr) + thermocycling (4.2..400 K). 2.Development of new physical techniques of accelerated laboratory simulation of the basic space factors adequate to natural factors influencing materials, components, units and scale models of spacecraft. In our opinion, this work solves a number of topical problems of ground-based simulation of space factors. 1.Simultaneous impact of six SF on spacecraft materials and models. 2.Simulation of the complete electromagnetic solar radiation (including VUV) spectrum in the wavelength range 5..2500 nm. 3.Accelerated simulation of the electron and proton flows of the Earth's radiation belts (the energy 50..200 keV, intensity 1012 particle/cm2s), i.e. with the acceleration coefficient 500..1000. 4.Accelerated simulation of the VUV component of the Sun's spectrum with the maximum intensity 3000 erg/cm2s) (i.e., the acceleration coefficient 300) 5.Simultaneous thermocycling of test objects in a wide range of temperatures 4.2..400 K in the vacuum of 10-6 Torr.

  4. Hydrologic consistency as a basis for assessing complexity of monthly water balance models for the continental United States

    NASA Astrophysics Data System (ADS)

    Martinez, Guillermo F.; Gupta, Hoshin V.

    2011-12-01

    Methods to select parsimonious and hydrologically consistent model structures are useful for evaluating dominance of hydrologic processes and representativeness of data. While information criteria (appropriately constrained to obey underlying statistical assumptions) can provide a basis for evaluating appropriate model complexity, it is not sufficient to rely upon the principle of maximum likelihood (ML) alone. We suggest that one must also call upon a "principle of hydrologic consistency," meaning that selected ML structures and parameter estimates must be constrained (as well as possible) to reproduce desired hydrological characteristics of the processes under investigation. This argument is demonstrated in the context of evaluating the suitability of candidate model structures for lumped water balance modeling across the continental United States, using data from 307 snow-free catchments. The models are constrained to satisfy several tests of hydrologic consistency, a flow space transformation is used to ensure better consistency with underlying statistical assumptions, and information criteria are used to evaluate model complexity relative to the data. The results clearly demonstrate that the principle of consistency provides a sensible basis for guiding selection of model structures and indicate strong spatial persistence of certain model structures across the continental United States. Further work to untangle reasons for model structure predominance can help to relate conceptual model structures to physical characteristics of the catchments, facilitating the task of prediction in ungaged basins.

  5. Shock-drift acceleration of interstellar pickup protons at the solar wind termination shock: Self-consistent 3D kinetic-gasdynamic model

    NASA Astrophysics Data System (ADS)

    Chalov, Sergei; Malama, Yury; Alexashov, Dmitry; Izmodenov, Vladislav; Izmodenov, Vladislav

    The numerical model of the shock-drift acceleration of interstellar pickup protons at the three-dimensional solar wind termination shock is presented. The model takes into account multiple reflections of the particles at and passing through the shock in the forward and reverse directions. The processes of the multiple interactions with the shock are possible due to pitch-angle scattering of protons in the upstream and downstream parts of the plasma flow. The model takes into account variations of the magnetic field direction in a vicinity of the shock connected with passing of the sector structure of the interplanetary magnetic field through the shock front at low ecliptic latitudes. The main advantage of the model is the self-consistent treatment of protons and interstellar hydrogen atoms, which are described kinetically and interact with protons through the resonant charge exchange process. The shock-drift acceleration can explain the fluxes of energetic protons measured at the Voyager~1/2 spacecraft after the termination shock crossings. No any pre-acceleration in the supersonic solar wind is needed to explain the data. The results of the model can be used to interpret the interstellar atom fluxes measured at the IBEX spacecraft.

  6. A remote Lewis acid trigger dramatically accelerates biaryl reductive elimination from a platinum complex.

    PubMed

    Liberman-Martin, Allegra L; Bergman, Robert G; Tilley, T Don

    2013-07-01

    A strategy for the control of electron density at a metal center is reported, which uses a remote chemical switch involving second-sphere Lewis acid binding that modulates electron density in the first coordination sphere. Binding of the Lewis acid B(C6F5)3 at remote nitrogen positions of a bipyrazine-diarylplatinum(II) complex accelerates biaryl reductive elimination by a factor of 64,000. PMID:23789917

  7. A consistent and conservative scheme for MHD flows with complex boundaries on an unstructured Cartesian adaptive system

    SciTech Connect

    Zhang, Jie; Ni, Ming-Jiu

    2014-01-01

    The numerical simulation of Magnetohydrodynamics (MHD) flows with complex boundaries has been a topic of great interest in the development of a fusion reactor blanket for the difficulty to accurately simulate the Hartmann layers and side layers along arbitrary geometries. An adaptive version of a consistent and conservative scheme has been developed for simulating the MHD flows. Besides, the present study forms the first attempt to apply the cut-cell approach for irregular wall-bounded MHD flows, which is more flexible and conveniently implemented under adaptive mesh refinement (AMR) technique. It employs a Volume-of-Fluid (VOF) approach to represent the fluid–conducting wall interface that makes it possible to solve the fluid–solid coupling magnetic problems, emphasizing at how electric field solver is implemented when conductivity is discontinuous in cut-cell. For the irregular cut-cells, the conservative interpolation technique is applied to calculate the Lorentz force at cell-center. On the other hand, it will be shown how consistent and conservative scheme is implemented on fine/coarse mesh boundaries when using AMR technique. Then, the applied numerical schemes are validated by five test simulations and excellent agreement was obtained for all the cases considered, simultaneously showed good consistency and conservative properties.

  8. Ion pre-acceleration in fully self-consistent particle-in-cell simulations of supercritical perpendicular reforming shocks in multiple ion species plasmas

    SciTech Connect

    Rekaa, V. L.; Chapman, S. C.; Dendy, R. O.

    2014-08-10

    Supernova remnant and heliopause termination shock plasmas may contain significant populations of minority heavy ions, with relative number densities n{sub α}/n{sub i} up to 50%. Preliminary kinetic simulations of collisionless shocks in these environments showed that the reformation cycle and acceleration mechanisms at quasi-perpendicular shocks can depend on the value of n{sub α}/n{sub i} . Shock reformation unfolds on ion spatio-temporal scales, requiring fully kinetic simulations of particle dynamics, together with the self-consistent electric and magnetic fields. This paper presents the first set of particle-in-cell simulations for two ion species, protons (n{sub p} ) and α-particles (n{sub α}), with differing mass and charge-to-mass ratios, that spans the entire range of n{sub α}/n{sub i} from 0% to 100%. The interplay between the differing gyro length scales and timescales of the ion species is crucial to the time-evolving phenomenology of the shocks, the downstream turbulence, and the particle acceleration at different n{sub α}/n{sub i} . We show how the overall energization changes with n{sub α}/n{sub i} , and relate this to the processes individual ions undergo in the shock region and in the downstream turbulence, and to the power spectra of magnetic field fluctuations. The crossover between shocks dominated by the respective ion species happens when n{sub α}/n{sub i} = 25%, and minority ion energization is strongest in this regime. Energization of the majority ion species scales with injection energy. The power spectrum of the downstream turbulence includes peaks at sequential ion cyclotron harmonics, suggestive of ion ring-beam collective instability.

  9. Multi-cavity complex controller with vector simulator for TESLA technology linear accelerator

    NASA Astrophysics Data System (ADS)

    Czarski, Tomasz; Pozniak, Krzysztof T.; Romaniuk, Ryszard S.; Szewinski, Jaroslaw

    2008-01-01

    A digital control, as the main part of the Low Level RF system, for superconducting cavities of a linear accelerator is presented. The FPGA based controller, supported by MATLAB system, was developed to investigate a novel firmware implementation. The complex control algorithm based on the non-linear system identification is the proposal verified by the preliminary experimental results. The general idea is implemented as the Multi-Cavity Complex Controller (MCC) and is still under development. The FPGA based controller executes procedure according to the prearranged control tables: Feed-Forward, Set-Point and Corrector unit, to fulfill the required cavity performance: driving in the resonance during filling and field stabilization for the flattop range. Adaptive control algorithm is applied for the feed-forward and feedback modes. The vector Simulator table has been introduced for an efficient verification of the FPGA controller structure. Experimental results of the internal simulation, are presented for a cavity representative condition.

  10. Boron carbide: Consistency of components, lattice parameters, fine structure and chemical composition makes the complex structure reasonable

    NASA Astrophysics Data System (ADS)

    Werheit, Helmut

    2016-10-01

    The complex, highly distorted structure of boron carbide is composed of B12 and B11C icosahedra and CBC, CBB and B□B linear elements, whose concentration depends on the chemical composition each. These concentrations are shown to be consistent with lattice parameters, fine structure data and chemical composition. The respective impacts on lattice parameters are estimated and discussed. Considering the contributions of the different structural components to the energy of the overall structure makes the structure and its variation within the homogeneity range reasonable; in particular that of B4.3C representing the carbon-rich limit of the homogeneity range. Replacing in B4.3C virtually the B□B components by CBC yields the hypothetical moderately distorted B4.0C (structure formula (B11C)CBC). The reduction of lattice parameters related is compatible with recently reported uncommonly prepared single crystals, whose compositions deviate from B4.3C.

  11. Optical and X-Ray Observations of GRB 060526: A Complex Afterglow Consistent with an Achromatic Jet Break

    NASA Technical Reports Server (NTRS)

    Dai, X.; Halpern, J. P.; Morgan, N. D.; Armstrong, E.; Mirabal, N.; Haislip. J. B.; Reichart, D. E.; Stanek, K. Z.

    2007-01-01

    We obtained 98 R-band and 18 B, r', i' images of the optical afterglow of GRB 060526 (z = 3.21) with the MDM 1.3 m, 2.4 m, and the PROMPT telescopes at CTIO over the five nights following the burst trigger. Combining these data with other optical observations reported in GCN and the Swift XRT observations, we compare the optical and X-ray afterglow light curves of GRB 060526. Both the optical and X-ray afterglow light curves show rich features, such as flares and breaks. The densely sampled optical observations provide very good coverage at T > 10(exp 4) s. We observed a break at 2.4 x 10(exp 5) sin the optical afterglow light curve. Compared with the X-ray afterglow light curve, the break is consistent with an achromatic break supporting the beaming models of GRBs. However, the prebreak and postbreak temporal decay slopes are difficult to explain in simple afterglow models. We estimated a jet angle of theta(sub j) approx. 7deg and a prompt emission size of R(sub prompt) approx. 2 x 10(exp 14) cm. In addition, we detected several optical flares with amplitudes of (Delta)m approx. 0.2,0.6, and 0.2 mag. The X-ray afterglows detected by Swift have shown complicated decay patterns. Recently, many well-sampled optical afterglows also show decays with flares and multiple breaks. GRB 060526 provides an additional case of such a complex, well-observed optical afterglow. The accumulated well-sampled afterglows indicate that most of the optical afterglows are complex.

  12. Uranyl adsorption and surface speciation at the imogolite-water interface: Self-consistent spectroscopic and surface complexation models

    USGS Publications Warehouse

    Arai, Y.; McBeath, M.; Bargar, J.R.; Joye, J.; Davis, J.A.

    2006-01-01

    Macro- and molecular-scale knowledge of uranyl (U(VI)) partitioning reactions with soil/sediment mineral components is important in predicting U(VI) transport processes in the vadose zone and aquifers. In this study, U(VI) reactivity and surface speciation on a poorly crystalline aluminosilicate mineral, synthetic imogolite, were investigated using batch adsorption experiments, X-ray absorption spectroscopy (XAS), and surface complexation modeling. U(VI) uptake on imogolite surfaces was greatest at pH ???7-8 (I = 0.1 M NaNO3 solution, suspension density = 0.4 g/L [U(VI)]i = 0.01-30 ??M, equilibration with air). Uranyl uptake decreased with increasing sodium nitrate concentration in the range from 0.02 to 0.5 M. XAS analyses show that two U(VI) inner-sphere (bidentate mononuclear coordination on outer-wall aluminol groups) and one outer-sphere surface species are present on the imogolite surface, and the distribution of the surface species is pH dependent. At pH 8.8, bis-carbonato inner-sphere and tris-carbonato outer-sphere surface species are present. At pH 7, bis- and non-carbonato inner-sphere surface species co-exist, and the fraction of bis-carbonato species increases slightly with increasing I (0.1-0.5 M). At pH 5.3, U(VI) non-carbonato bidentate mononuclear surface species predominate (69%). A triple layer surface complexation model was developed with surface species that are consistent with the XAS analyses and macroscopic adsorption data. The proton stoichiometry of surface reactions was determined from both the pH dependence of U(VI) adsorption data in pH regions of surface species predominance and from bond-valence calculations. The bis-carbonato species required a distribution of surface charge between the surface and ?? charge planes in order to be consistent with both the spectroscopic and macroscopic adsorption data. This research indicates that U(VI)-carbonato ternary species on poorly crystalline aluminosilicate mineral surfaces may be important in

  13. Scalar Transport and Dispersion in Complex Terrain within a High Resolution Mass-Consistent Wind Modeling Framework

    NASA Astrophysics Data System (ADS)

    Wagenbrenner, N. S.; Edburg, S. L.; Lamb, B.; Forthofer, J.

    2012-12-01

    In areas of complex terrain, fine-scale changes in topography or vegetation substantially alter the flow field, and in turn, the transport and dispersion of air pollutants, pheromones, or other scalars. Thus, accurate modeling of scalar transport in complex topography requires accurate prediction of the flow field at a high spatial resolution. Mesoscale weather models typically operate on horizontal grids of 4 km or larger and are not capable of handling the effects of sub-grid complex terrain, such as wind speed-up over ridges, flow channeling in valleys, flow separation around terrain obstacles, and enhanced surface roughness from vegetation. In this paper we describe a scalar transport algorithm (advection and turbulent diffusion) used with WindNinja, a high-resolution mass-consistent wind model. WindNinja operates on a terrain-following coordinate system with a hexahedral cell mesh that grows in vertical size with height above the ground. A variational calculus approach is used in WindNinja that results in fast run times on the order of one minute for a 50 km x 50 km domain and 100 m horizontal resolution. The advection-diffusion algorithm uses a first order closure scheme for turbulent diffusion, where diffusivities are parameterized based on mixing length theory and modified as a function of atmospheric stability. We initialize WindNinja simulations with output from mesoscale weather forecasts using the Weather Research and Forecasting (WRF) model to capture the large-scale atmospheric flows and stability conditions. Model performance is evaluated against field data collected under a range of conditions at different locations including a multi-day continuous tracer gas dispersion experiment in an orchard located on rolling terrain in eastern Washington and a post-wildfire PM10 monitoring campaign in SE Idaho. The combination of fast run times, low computational demands, and explicit treatment of terrain and vegetation at a high spatial resolution are expected

  14. Accelerated acidification by inoculation with a microbial consortia in a complex open environment.

    PubMed

    Yu, Jiadong; Zhao, Ye; Liu, Bin; Zhao, Yubin; Wu, Jingwei; Yuan, Xufeng; Zhu, Wanbin; Cui, Zongjun

    2016-09-01

    Bioaugmentation using microbial consortia is helpful in some anaerobic digestion (AD) systems, but accelerated acidification to produce methane has not been performed effectively with corn stalks and cow dung. In this study, the thermophilic microbial consortia MC1 was inoculated into a complex open environment (unsterilized and sterilized systems) to evaluate the feasibility of bioaugmentation to improve acidification efficiency. The results indicated that MC1 itself degraded lignocellulose efficiently, and accumulated more organic acids within 3days. Similar trends were also observed in the unsterilized system, where the hemicellulose degradation rate and organic acid concentrations increased significantly by two-fold and 20.1% (P<0.05), respectively, and clearly reduced the loss of product. Microbial composition did not change obviously after inoculating MC1, but the abundance of members of MC1, such as Bacillus and Clostridium, increased clearly on day 3. Finally, the acidogenic fluid improved methane yield significantly (P<0.05) via bioaugmentation. PMID:27253477

  15. mRNA export through an additional cap-binding complex consisting of NCBP1 and NCBP3

    PubMed Central

    Gebhardt, Anna; Habjan, Matthias; Benda, Christian; Meiler, Arno; Haas, Darya A.; Hein, Marco Y.; Mann, Angelika; Mann, Matthias; Habermann, Bianca; Pichlmair, Andreas

    2015-01-01

    The flow of genetic information from DNA to protein requires polymerase-II-transcribed RNA characterized by the presence of a 5′-cap. The cap-binding complex (CBC), consisting of the nuclear cap-binding protein (NCBP) 2 and its adaptor NCBP1, is believed to bind all capped RNA and to be necessary for its processing and intracellular localization. Here we show that NCBP1, but not NCBP2, is required for cell viability and poly(A) RNA export. We identify C17orf85 (here named NCBP3) as a cap-binding protein that together with NCBP1 forms an alternative CBC in higher eukaryotes. NCBP3 binds mRNA, associates with components of the mRNA processing machinery and contributes to poly(A) RNA export. Loss of NCBP3 can be compensated by NCBP2 under steady-state conditions. However, NCBP3 becomes pivotal under stress conditions, such as virus infection. We propose the existence of an alternative CBC involving NCBP1 and NCBP3 that plays a key role in mRNA biogenesis. PMID:26382858

  16. Complex microstructures of ABC triblock copolymer thin films directed by polymer brushes based on self-consistent field theory.

    PubMed

    Jiang, Zhibin; Xu, Chang; Qiu, Yu Dong; Wang, Xiaoliang; Zhou, Dongshan; Xue, Gi

    2014-01-01

    The morphology and the phase diagram of ABC triblock copolymer thin film directed by polymer brushes are investigated by the self-consistent field theory in three dimensions. The polymer brushes coated on the substrate can be used as a good soft template to tailor the morphology of the block copolymer thin films compared with those on the hard substrates. The polymer brush is identical with the middle block B. By continuously changing the composition of the block copolymer, the phase diagrams are constructed for three cases with the fixed film thickness and the brush density: identical interaction parameters, frustrated and non-frustrated cases. Some ordered complex morphologies are observed: parallel lamellar phase with hexagonally packed pores at surfaces (LAM3 (ll) -HFs), perpendicular lamellar phase with cylinders at the interface (LAM(⊥)-CI), and perpendicular hexagonally packed cylinders phase with rings at the interface (C2 (⊥)-RI). A desired direction (perpendicular or parallel to the coated surfaces) of lamellar phases or cylindrical phases can be obtained by varying the composition and the interactions between different blocks. The phase diagram of ABC triblock copolymer thin film wetted between the polymer brush-coated surfaces is very useful in designing the directed pattern of ABC triblock copolymer thin film. PMID:25114650

  17. Accelerated lambing achieved by a photoperiod regimen consisting of alternating 4-month sequences of long and short days applied year-round.

    PubMed

    Cameron, J; Malpaux, B; Castonguay, F W

    2010-10-01

    The objective of this work was to evaluate the reproductive performance of ewes exposed to a photoperiodic regimen consisting of continuous alternating 4-mo periods of long days (LD: 16 h of light/d) and short days (SHD: 8 h of light/d) in an accelerated lambing program of 3 lambings in 2 yr. A total of 211 prolific Rideau Arcott ewes were assigned to the photoperiodic treatment, whereas 37 ewes were maintained under natural annual variation in day length (control group). Ewes under the photoperiod regimen were divided into 4 subgroups (A, B, C, D). All these groups of ewes were exposed to the same light regimen, but the LD and SHD light sequences were staggered by 2 mo to permit the evaluation of the effect of time and season of mating on performance of the ewes treated with the photoperiod. The control ewes were treated with intravaginal sponges in the out-of-season breeding periods (conventional approach). Each group of ewes was studied over 3 reproductive cycles. Two groups of rams exposed to alternating 2-mo sequences of LD and SHD were used for mating. The short mean interval between ram introduction and conception for the groups exposed to artificial photoperiod (9.4 d) confirmed the effectiveness of the treatment to induce intense sexual activity. For the 12 breeding periods studied (8 in out-of-season and 4 in sexual season), fertility rate of the ewes treated with photoperiod, mated at various times of year, was 91.6%, which is comparable with the fertility normally seen in the natural breeding season. The number of lambs born/ewe remained constant across reproductive cycles and was greater in photoperiod-treated groups (2.81 vs. 2.27 for photoperiod and control groups, respectively; P = 0.0002). Groups exposed to photoperiod treatment obtained better fertility rate than the control group in out-of-season breeding (91.1 vs. 76.3%; P = 0.016). Ewes managed under the photoperiod regimen produced 1.38 lambings/yr and 69% of them lambed 3 times in 2 yr

  18. A surface complexation model for sulfate and selenate on iron oxides consistent with spectroscopic and theoretical molecular evidence

    NASA Astrophysics Data System (ADS)

    Fukushi, Keisuke; Sverjensky, Dimitri A.

    2007-01-01

    Sulfate and selenate adsorption on iron oxides are important reactions in natural systems under a very wide range of pH values, ionic strengths, and electrolyte compositions. Under such conditions, spectroscopic and theoretical calculations have demonstrated the potential importance of a variety of surface species. Understanding the variations in the surface speciation of these oxyanions is fundamental to prediction of their partitioning between minerals and aqueous solutions. In the present study, published experimental spectroscopic and theoretical molecular evidence of the identity of sulfate/selenate surface species are integrated with a surface complexation model consistent with a wide variety of experimental adsorption, surface titration, and proton coadsorption data to define the surface speciation of sulfate and selenate on iron oxides under a wide range of conditions. The analysis was carried out with the extended triple layer model (ETLM) taking into account the electrostatics of water dipole desorption during ligand exchange reactions. On seven out of eight goethites studied, sulfate and selenate surface reactions can be represented by the formation of a monodentate-mononuclear inner-sphere and a bidentate-binuclear outer-sphere (or H-bonded) species according to >FeOH+H+AO42-=>FeOAO3-+HO and 2>FeOH+2H+AO42-=(>FeOH2+)2_AO42- respectively, where A stands for S or Se. The model predicted changes in the proportions of the species with pH, ionic strength and surface coverage consistent with independently derived experimental evidence from in situ Raman, ATR-FTIR and EXAFS studies. In contrast to goethite, the ETLM analysis of sulfate and selenate adsorption on hydrous ferric oxide (HFO) required an additional outer-sphere (or H-bonded) surface species represented by, >FeOH+2H+AO42-=>FeOH2+_HAO4- Equilibrium constants for sulfate and selenate adsorption based on site-occupancy standard states ( Kθ) for >FeOAO3- and (>FeOH2+)2_AO42- on HFO are systematically

  19. Chitosan oligosaccharide-Ca complex accelerates the depuration of cadmium from Chlamys ferrari

    NASA Astrophysics Data System (ADS)

    Huang, Guoqing; Sun, Jipeng; Wang, Dongfeng; Xu, Ying; Xu, Wei

    2012-06-01

    This study investigated the effect of a chitosan oligosaccharide-Ca complex (COS-Ca) on the depuration of cadmium (Cd) from Chlamys ferrari. After exposure to 0.5 mg L-1 CdCl2 for 3 or 7 d, the scallops were treated by COS-Ca prior to determination of Cd, calcium (Ca) and zinc (Zn) contents, Cd distribution in organs, malondialdehyde (MDA) content and antioxidant variables. Results showed that COS-Ca reduced Cd content in the viscera of the scallops, with highest Cd depuration rate (47%) observed on day 3. The COS-Ca concentration substantially affected Cd depuration, and the exposure to 8.75 mg L-1 COS-Ca led to significantly higher Cd depuration rate compared with those of lower COS-Ca concentrations (1.75, 3.5, 5.25, and 7.00 mg L-1). Distribution analysis of Cd in scallop organs indicated that COS-Ca significantly reduced Cd content in the kidney throughout the 5-d experiment, as well as in the gill during the early stage of Cd depuration. In addition, COS-Ca treatment decreased glutathione peroxidase (GSH-Px) activity and MDA content while increasing superoxide dismutase (SOD) and catalase (CAT) activities on different days. Our work suggested COS-Ca complex treatment as an effective method for acceleration of Cd depuration from Cd-contaminated bivalves.

  20. Electrostatic free energy of weakly charged macromolecules in solution and intermacromolecular complexes consisting of oppositely charged polymers.

    PubMed

    Biesheuvel, P Maarten; Cohen Stuart, Martien A

    2004-03-30

    When oppositely charged polyelectrolytes are mixed in water, attraction between oppositely charged groups may lead to the formation of polyelectrolyte complexes (associative phase separation, complex coacervation, interpolymer complexes). Theory is presented to describe the electrostatic free energy change when ionizable (annealed) (macro-)molecules form a macroscopic polyelectrolyte complex. The electrostatic free energy includes an electric term as well as a chemical term that is related to the dissociation of the ionic groups in the polymer. An example calculation for complexation of polyacid with polybase uses a cylindrical diffuse double layer model for free polymer in solution and electroneutrality within the complex and calculates the free energy of the system when the polymer is in solution or in a polyelectrolyte complex. Combined with a term for the nonelectrostatic free energy change upon complexation, a theoretical stability diagram is constructed that relates pH, salt concentration, and mixing ratio, which is in qualitative agreement with an experimental diagram obtained by Bungenberg de Jong (1949) for complex coacervation of arabic gum and gelatin. The theory furthermore explains the increased tendency toward phase separation when the polymer becomes more strongly charged and suggests that complexation of polyacid or polybase with zwitterionic polymer (e.g., protein) of the same charge sign (at the "wrong side" of the iso-electric point) may be due (in part) to an induced charge reversal of the protein.

  1. Finite difference method accelerated with sparse solvers for structural analysis of the metal-organic complexes

    NASA Astrophysics Data System (ADS)

    Guda, A. A.; Guda, S. A.; Soldatov, M. A.; Lomachenko, K. A.; Bugaev, A. L.; Lamberti, C.; Gawelda, W.; Bressler, C.; Smolentsev, G.; Soldatov, A. V.; Joly, Y.

    2016-05-01

    Finite difference method (FDM) implemented in the FDMNES software [Phys. Rev. B, 2001, 63, 125120] was revised. Thorough analysis shows, that the calculated diagonal in the FDM matrix consists of about 96% zero elements. Thus a sparse solver would be more suitable for the problem instead of traditional Gaussian elimination for the diagonal neighbourhood. We have tried several iterative sparse solvers and the direct one MUMPS solver with METIS ordering turned out to be the best. Compared to the Gaussian solver present method is up to 40 times faster and allows XANES simulations for complex systems already on personal computers. We show applicability of the software for metal-organic [Fe(bpy)3]2+ complex both for low spin and high spin states populated after laser excitation.

  2. The Effects of Sex-Role Consistent and Inconsistent Information on the Social Perceptions of Complex, Noncomplex, Androgynous, and Sex-Typed Women.

    ERIC Educational Resources Information Center

    Capurso, Rose J.; Blocher, Donald H.

    1985-01-01

    Examined the effects of differences in cognitive complexity and sex-role orientation on the person perceptions formed by young college women (N=88) when presented with information varied in terms of consistency of sex-role appropriate behavior. Results indicated that complex subjects produced more differentiated final impressions than noncomplex…

  3. Multi-core CPU or GPU-accelerated Multiscale Modeling for Biomolecular Complexes.

    PubMed

    Liao, Tao; Zhang, Yongjie; Kekenes-Huskey, Peter M; Cheng, Yuhui; Michailova, Anushka; McCulloch, Andrew D; Holst, Michael; McCammon, J Andrew

    2013-07-01

    Multi-scale modeling plays an important role in understanding the structure and biological functionalities of large biomolecular complexes. In this paper, we present an efficient computational framework to construct multi-scale models from atomic resolution data in the Protein Data Bank (PDB), which is accelerated by multi-core CPU and programmable Graphics Processing Units (GPU). A multi-level summation of Gaus-sian kernel functions is employed to generate implicit models for biomolecules. The coefficients in the summation are designed as functions of the structure indices, which specify the structures at a certain level and enable a local resolution control on the biomolecular surface. A method called neighboring search is adopted to locate the grid points close to the expected biomolecular surface, and reduce the number of grids to be analyzed. For a specific grid point, a KD-tree or bounding volume hierarchy is applied to search for the atoms contributing to its density computation, and faraway atoms are ignored due to the decay of Gaussian kernel functions. In addition to density map construction, three modes are also employed and compared during mesh generation and quality improvement to generate high quality tetrahedral meshes: CPU sequential, multi-core CPU parallel and GPU parallel. We have applied our algorithm to several large proteins and obtained good results.

  4. Applying accelerator mass spectrometry for low-level detection of complex engineered nanoparticles in biological media.

    PubMed

    Wang, Binghui; Jackson, George S; Yokel, Robert A; Grulke, Eric A

    2014-08-01

    Complex engineered nanoparticles (CENPs), which have different core and surface components, are being developed for medicinal, pharmaceutical and industrial applications. One of the key challenges for environmental health and safety assessments of CENPs is to identify and quantity their transformations in biological environments. This study reports the effects of in vivo exposure of citrate-coated nanoalumina with different rare isotope labels on each component. This CENP was dosed to the rat and accelerator mass spectrometry (AMS) was used to quantify (26)Al, (14)C, and their ratio in the dosing material and tissue samples. For CENPs detected in the liver, the rare isotope ratio, (14)C/(26)Al, was 87% of the dosing material's ratio. The citrate coating on the nanoalumina in the liver was stable or, if it degraded, its metabolites were incorporated with nearby tissues. However, in brain and bone where little alumina was detected, the rare isotope ratio greatly exceeded that of the dosing material. Therefore, in the animal, citrate dissociated from CENPs and redistributed to brain and bone. Tracking both the core and surface components by AMS presents a new approach for characterizing transformations of CENPs components in biological milieu or environments.

  5. A new slip stacking RF system for a twofold power upgrade of Fermilab's Accelerator Complex

    SciTech Connect

    Madrak, Robyn

    2014-09-11

    Fermilab@?s Accelerator Complex has been recently upgraded, in order to increase the 120GeV proton beam power on target from about 400kW to over 700kW for NO@nA and other future intensity frontier experiments. One of the key ingredients of the upgrade is the offloading of some Main Injector synchrotron operations - beam injection and RF manipulation called ''slip stacking'' - to the 8GeV Recycler Ring, which had until recently been used only for low-intensity antiproton storage and cooling. This required construction of two new 53MHz RF systems for the slip-stacking manipulations. The cavities operate simultaneously at V_p_e_a_k@?150kV, but at slightly different frequencies (@Df=1260Hz). Their installation was completed in September 2013. This paper describes the novel solutions used in the design of the new cavities, their tuning system, and the associated high power RF system. First results showing effective operation of the RF system, beam capture and successful slip-stacking in the Recycler Ring are presented.

  6. Mitochondrial Complex I Deficiency Increases Protein Acetylation and Accelerates Heart Failure

    PubMed Central

    Karamanlidis, Georgios; Lee, Chi Fung; Garcia-Menendez, Lorena; Kolwicz, Stephen C.; Suthammarak, Wichit; Gong, Guohua; Sedensky, Margaret M.; Morgan, Philip G.; Wang, Wang; Tian, Rong

    2013-01-01

    Summary Mitochondrial respiratory dysfunction is linked to the pathogenesis of multiple diseases including heart failure but the specific mechanisms for this link remain largely elusive. We modeled the impairment of mitochondrial respiration by inactivation of the Ndufs4 gene, a protein critical for Complex I (C-I) assembly, in the mouse heart (cKO). While C-I supported respiration decreased by >40%, the cKO mice maintained normal cardiac function in vivo and high-energy phosphate content in isolated perfused hearts. However, the cKO mice developed accelerated heart failure after pressure overload or repeated pregnancy. Decreased NAD+/NADH ratio by C-I deficiency inhibited Sirt3 activity, leading to increase in protein acetylation, and sensitization of the permeability transition in mitochondria (mPTP). NAD+ precursor supplementation to cKO mice partially normalized the NAD+/NADH ratio, protein acetylation and mPTP sensitivity. These findings describe a mechanism connecting mitochondrial dysfunction to the susceptibility to diseases and propose a potential therapeutic target. PMID:23931755

  7. New Models of Solar Wind Acceleration and Stream Interactions in the Sun's Topologically Complex Magnetic Field

    NASA Astrophysics Data System (ADS)

    Cranmer, S. R.; Van Ballegooijen, A. A.; Woolsey, L. N.

    2012-12-01

    The last decade has seen significant progress toward identifying and characterizing the processes that heat the corona and accelerate the solar wind. It is believed that the low-speed solar wind comes from a wide range of source regions in the corona, including streamers, pseudostreamers, active regions, and small coronal holes. These source regions tend to be associated with the most topologically complex magnetic fields, and it is unclear how the coronal field lines connect to the large-scale open heliospheric field. To learn more about these connections, we present new models of turbulence-driven coronal heating and solar wind acceleration along empirically constrained field lines. To begin, we chose a time period during which the footpoints linked to the ecliptic plane were rooted in Quiet Sun (QS) regions away from both large coronal holes and strong-field active regions. The weak and mixed-polarity QS field was observed at high resolution by the VSM instrument of SOLIS, and we extrapolated this field into the corona using the potential field source surface method. Time-steady 1D models of individual flux tubes were created with the ZEPHYR code (Cranmer et al. 2007) that solves the one-fluid equations of mass, momentum, and energy conservation from the photosphere to 4 AU. Then, to take account of stream-stream interactions between the flux tubes, we solved a 2D time-steady set of MHD conservation equations to determine the corotating longitudinal structure in the ecliptic plane. We aim to understand the extent to which fine-scale inter-tube plasma structures in the corona survive to large distances. In other words, we want to know how much of the coronal flux tube "spaghetti" is either shredded by turbulence or smeared out by stream interactions. We also plan to evaluate the level of high-resolution detail that is needed in coronal flux tube modeling in order to accurately predict the space weather consequences of various kinds of corotating structures in the

  8. Asymmetric mixed-valence complexes that consist of cyclometalated ruthenium and ferrocene: synthesis, characterization, and electronic-coupling studies.

    PubMed

    Wu, Si-Hai; Shen, Jun-Jian; Yao, Jiannian; Zhong, Yu-Wu

    2013-01-01

    Three bis-tridentate ferrocene-containing cyclometalated ruthenium complexes, [(Fcdpb)Ru(tpy)](+) (1(+)), [(Fctpy)Ru(dpb)](+) (2(+)), and [(Fcdpb)Ru(Fctpy)](+) (3(+)), have been prepared and characterized, where Fcdpb is the 2-deprotonated form of 1,3-di(2-pyridyl)-5-ferrocenylbenzene, tpy is 2,2':6',2"-terpyridine, dpb is the 2-deprotonated form of 1,3-di(2-pyridyl)benzene, and Fctpy is 4'-ferrocenyl-2,2':6',2"-terpyridine. Single crystals of compounds 2(+) and 3(+) have been studied by X-ray analysis. Complexes 1(+) and 2(+) displayed two anodic redox waves, whilst three well-separated redox couples were observed for compound 3(+). A combined experimental and computational study suggested that the ferrocene unit on the Fcdpb moiety in compounds 1(+) and 3(+) was oxidized first. In contrast, the order of the oxidation of ruthenium and ferrocene in complex 2(+) was reversed. Metal-to-metal-charge-transfer transitions (MM'CT) have been observed for the singly oxidized states 1(2+), 2(2+), and 3(2+) in the near-infrared region. Hush analysis showed that the metal-metal electronic couplings in compounds 1(2+) and 3(2+) were much stronger than those in compound 2(2+).

  9. STOCHASTIC ACCELERATION AND THE EVOLUTION OF SPECTRAL DISTRIBUTIONS IN SYNCHRO-SELF-COMPTON SOURCES: A SELF-CONSISTENT MODELING OF BLAZARS' FLARES

    SciTech Connect

    Tramacere, A.; Taylor, A. M.; Massaro, E.

    2011-10-01

    The broadband spectral distributions of non-thermal sources, such as those of several known blazars, are well described by a log-parabolic fit. The second-degree term in these fits measures the curvature in the spectrum. In this paper, we investigate whether the curvature parameter observed in the spectra of the synchrotron emission can be used as a fingerprint of stochastic acceleration. As a first approach, we use the multiplicative central limit theorem to show how fluctuations in the energy gain result in the broadening of the spectral shape, introducing a curvature into the energy distribution. Then, by means of a Monte Carlo description, we investigate how the curvature produced in the electron distribution is linked to the diffusion in momentum space. To get a more generic description of the problem we turn to the diffusion equation in momentum space. We first study some 'standard' scenarios, in order to understand the conditions that make the curvature in the spectra significant, and the relevance of cooling during the acceleration process. We try to quantify the correlation between the curvature and the diffusive process in the pre-equilibrium stage, and investigate how the transition between the Klein-Nishina and the Thomson regimes, in inverse Compton cooling, determine the curvature in the distribution at equilibrium. We apply these results to some observed trends, such as the anticorrelation between the peak energy and the curvature term observed in the spectra of Mrk 421, and a sample of BL Lac objects whose synchrotron emission peaks at X-ray energies.

  10. Ab initio nonadiabatic dynamics of multichromophore complexes: a scalable graphical-processing-unit-accelerated exciton framework.

    PubMed

    Sisto, Aaron; Glowacki, David R; Martinez, Todd J

    2014-09-16

    ("fragmenting") a molecular system and then stitching it back together. In this Account, we address both of these problems, the first by using graphical processing units (GPUs) and electronic structure algorithms tuned for these architectures and the second by using an exciton model as a framework in which to stitch together the solutions of the smaller problems. The multitiered parallel framework outlined here is aimed at nonadiabatic dynamics simulations on large supramolecular multichromophoric complexes in full atomistic detail. In this framework, the lowest tier of parallelism involves GPU-accelerated electronic structure theory calculations, for which we summarize recent progress in parallelizing the computation and use of electron repulsion integrals (ERIs), which are the major computational bottleneck in both density functional theory (DFT) and time-dependent density functional theory (TDDFT). The topmost tier of parallelism relies on a distributed memory framework, in which we build an exciton model that couples chromophoric units. Combining these multiple levels of parallelism allows access to ground and excited state dynamics for large multichromophoric assemblies. The parallel excitonic framework is in good agreement with much more computationally demanding TDDFT calculations of the full assembly. PMID:25186064

  11. Prototype of a test bench for applied research on Extracted beams of the nuclotron accelerator complex

    NASA Astrophysics Data System (ADS)

    Baldin, A. A.; Berlev, A. I.; Bradnova, V.; Butenko, A. V.; Fedorov, A. N.; Kudashkin, I. V.

    2016-05-01

    The results of the development and testing of elements of a test bench for investigating the impact of accelerated particle beams on biological objects, electronics, and other targets are presented. The systems for beam monitoring and target positioning were tested on extracted argon beams in the framework of experiments on studying the radiation hardness of electronic components.

  12. A meiotic chromosomal core consisting of cohesin complex proteins recruits DNA recombination proteins and promotes synapsis in the absence of an axial element in mammalian meiotic cells.

    PubMed

    Pelttari, J; Hoja, M R; Yuan, L; Liu, J G; Brundell, E; Moens, P; Santucci-Darmanin, S; Jessberger, R; Barbero, J L; Heyting, C; Höög, C

    2001-08-01

    The behavior of meiotic chromosomes differs in several respects from that of their mitotic counterparts, resulting in the generation of genetically distinct haploid cells. This has been attributed in part to a meiosis-specific chromatin-associated protein structure, the synaptonemal complex. This complex consist of two parallel axial elements, each one associated with a pair of sister chromatids, and a transverse filament located between the synapsed homologous chromosomes. Recently, a different protein structure, the cohesin complex, was shown to be associated with meiotic chromosomes and to be required for chromosome segregation. To explore the functions of the two different protein structures, the synaptonemal complex and the cohesin complex, in mammalian male meiotic cells, we have analyzed how absence of the axial element affects early meiotic chromosome behavior. We find that the synaptonemal complex protein 3 (SCP3) is a main determinant of axial-element assembly and is required for attachment of this structure to meiotic chromosomes, whereas SCP2 helps shape the in vivo structure of the axial element. We also show that formation of a cohesin-containing chromosomal core in meiotic nuclei does not require SCP3 or SCP2. Our results also suggest that the cohesin core recruits recombination proteins and promotes synapsis between homologous chromosomes in the absence of an axial element. A model for early meiotic chromosome pairing and synapsis is proposed. PMID:11463847

  13. Particle acceleration in a complex solar active region modelled by a Cellular automata model

    NASA Astrophysics Data System (ADS)

    Dauphin, C.; Vilmer, N.; Anastasiadis, A.

    2004-12-01

    The models of cellular automat allowed to reproduce successfully several statistical properties of the solar flares. We use a cellular automat model based on the concept of self-organised critical system to model the evolution of the magnetic energy released in an eruptive active area. Each burst of magnetic energy released is assimilated to a process of magnetic reconnection. We will thus generate several current layers (RCS) where the particles are accelerated by a direct electric field. We calculate the energy gain of the particles (ions and electrons) for various types of magnetic configuration. We calculate the distribution function of the kinetic energy of the particles after their interactions with a given number of RCS for each type of configurations. We show that the relative efficiency of the acceleration of the electrons and the ions depends on the selected configuration.

  14. Diffractive stacks of metamaterial lattices with a complex unit cell: Self-consistent long-range bianisotropic interactions in experiment and theory

    NASA Astrophysics Data System (ADS)

    Kwadrin, Andrej; Koenderink, A. Femius

    2014-01-01

    Metasurfaces and metamaterials promise arbitrary rerouting of light using two-dimensional (2D) planar arrangements of electric and magnetic scatterers, respectively, 3D stacks built out of such 2D planes. An important problem is how to self-consistently model the response of these systems in a manner that retains dipole intuition yet does full justice to the self-consistent multiple scattering via near-field and far-field retarded interactions. We set up such a general model for metamaterial lattices of complex 2D unit cells of poly-atomic basis as well as allowing for stacking in a third dimension. In particular, each scatterer is quantified by a magnetoelectric polarizability tensor and Ewald lattice summation deals with all near-field and long-range retarded electric, magnetic, and magnetoelectric couplings self-consistently. We show in theory and experiment that grating diffraction orders of dilute split ring lattices with complex unit cells show a background-free signature of magnetic dipole response. For denser lattices experiment and theory show that complex unit cells can reduce the apparent effect of bianisotropy, i.e., the strong oblique-incidence handed response that was reported for simple split ring lattices. Finally, the method is applied to calculate transmission of finite stacks of lattices. Thereby our simple methodology allows us to trace the emergence of effective material constants when building a 3D metamaterial layer by layer, as well as facilitating the design of metasurfaces.

  15. Particle acceleration and radiation in flaring complex solar active regions modeled by cellular automata

    NASA Astrophysics Data System (ADS)

    Dauphin, C.; Vilmer, N.; Anastasiadis, A.

    2007-06-01

    Context: We study the acceleration and radiation of electrons and ions interacting with multiple small-scale dissipation regions resulting from the magnetic energy release process. Aims: We aim to calculate the distribution functions of the kinetic energy of the particles and the X-ray spectra and γ-ray fluxes produced by the accelerated particles. Methods: The evolution of the magnetic energy released in an active region is mimicked by a cellular automaton model based on the concept of self-organized criticality. Each burst of magnetic energy release is associated with a reconnecting current sheet (RCS) in which the particles are accelerated by a direct electric field. Results: We calculate the energy gain of the particles (ions and electrons) for three different magnetic configurations of the RCS after their interactions with a given number of RCS. We finally compare our results with existing observations. Conclusions: The results of our simulation can reproduce several properties of the observations such as variable electron and ion energy contents and γ-ray line ratio. Even if very flat X-ray spectra have been reported in a few events, the X-ray spectra produced in this model are too flat when compared to most X-ray observations.

  16. Tsallis entropy and complexity theory in the understanding of physics of precursory accelerating seismicity.

    NASA Astrophysics Data System (ADS)

    Vallianatos, Filippos; Chatzopoulos, George

    2014-05-01

    Strong observational indications support the hypothesis that many large earthquakes are preceded by accelerating seismic release rates which described by a power law time to failure relation. In the present work, a unified theoretical framework is discussed based on the ideas of non-extensive statistical physics along with fundamental principles of physics such as the energy conservation in a faulted crustal volume undergoing stress loading. We derive the time-to-failure power-law of: a) cumulative number of earthquakes, b) cumulative Benioff strain and c) cumulative energy released in a fault system that obeys a hierarchical distribution law extracted from Tsallis entropy. Considering the analytic conditions near the time of failure, we derive from first principles the time-to-failure power-law and show that a common critical exponent m(q) exists, which is a function of the non-extensive entropic parameter q. We conclude that the cumulative precursory parameters are function of the energy supplied to the system and the size of the precursory volume. In addition the q-exponential distribution which describes the fault system is a crucial factor on the appearance of power-law acceleration in the seismicity. Our results based on Tsallis entropy and the energy conservation gives a new view on the empirical laws derived by other researchers. Examples and applications of this technique to observations of accelerating seismicity will also be presented and discussed. This work was implemented through the project IMPACT-ARC in the framework of action "ARCHIMEDES III-Support of Research Teams at TEI of Crete" (MIS380353) of the Operational Program "Education and Lifelong Learning" and is co-financed by the European Union (European Social Fund) and Greek national funds

  17. Accelerating the Association of the Most Stable Protein-Ligand Complex by More than Two Orders of Magnitude.

    PubMed

    Giese, Christoph; Eras, Jonathan; Kern, Anne; Schärer, Martin A; Capitani, Guido; Glockshuber, Rudi

    2016-08-01

    The complex between the bacterial type 1 pilus subunit FimG and the peptide corresponding to the N-terminal extension (termed donor strand, Ds) of the partner subunit FimF (DsF) shows the strongest reported noncovalent molecular interaction, with a dissociation constant (KD ) of 1.5×10(-20)  m. However, the complex only exhibits a slow association rate of 330 m(-1)  s(-1) that limits technical applications, such as its use in affinity purification. Herein, a structure-based approach was used to design pairs of FimGt (a FimG variant lacking its own N-terminal extension) and DsF variants with enhanced electrostatic surface complementarity. Association of the best mutant FimGt/DsF pairs was accelerated by more than two orders of magnitude, while the dissociation rates and 3D structures of the improved complexes remained essentially unperturbed. A KD  value of 8.8×10(-22)  m was obtained for the best mutant complex, which is the lowest value reported to date for a protein/ligand complex. PMID:27351462

  18. Accelerating the Association of the Most Stable Protein-Ligand Complex by More than Two Orders of Magnitude.

    PubMed

    Giese, Christoph; Eras, Jonathan; Kern, Anne; Schärer, Martin A; Capitani, Guido; Glockshuber, Rudi

    2016-08-01

    The complex between the bacterial type 1 pilus subunit FimG and the peptide corresponding to the N-terminal extension (termed donor strand, Ds) of the partner subunit FimF (DsF) shows the strongest reported noncovalent molecular interaction, with a dissociation constant (KD ) of 1.5×10(-20)  m. However, the complex only exhibits a slow association rate of 330 m(-1)  s(-1) that limits technical applications, such as its use in affinity purification. Herein, a structure-based approach was used to design pairs of FimGt (a FimG variant lacking its own N-terminal extension) and DsF variants with enhanced electrostatic surface complementarity. Association of the best mutant FimGt/DsF pairs was accelerated by more than two orders of magnitude, while the dissociation rates and 3D structures of the improved complexes remained essentially unperturbed. A KD  value of 8.8×10(-22)  m was obtained for the best mutant complex, which is the lowest value reported to date for a protein/ligand complex.

  19. Using Narrative Intervention to Accelerate Canonical Story Grammar and Complex Language Growth in Culturally Diverse Preschoolers

    ERIC Educational Resources Information Center

    Petersen, Douglas B.; Spencer, Trina D.

    2016-01-01

    Oral narratives are a commonly used, meaningful means of communication that reflects academic language. New state curriculum standards include narrative-related language expectations for young school-age children, including story grammar and complex language. This article provides a review of preschool narrative-based language intervention…

  20. Self-Reported Responses to Player Profile Questions Show Consistency with the Use of Complex Attentional Strategies by Expert Horseshoe Pitchers

    PubMed Central

    Fairbrother, Jeffrey T.; Post, Phillip G.; Whalen, Sam J.

    2016-01-01

    The advantages on an external focus of attention have been demonstrated for a variety of sport tasks. The constrained action hypothesis (Wulf et al., 2001) argues that focusing externally on the movement effect results in the use of automated processes for movement control. In contrast, focusing internally in an attempt to control the movements of the body disrupts normally automated processes and degrades performance. Research on experts, however, suggests that they may adopt more complex attentional strategies. The present study provided a unique opportunity to examine expert horseshoe players’ attentional strategies as indicated by their self-reported responses to questions included in a National Horseshoe Pitchers Association (NHPA) player profile questionnaire. Responses submitted by 83 top NHPA players were examined to determine the frequency of references to the use of internal and external focus points and identify categories related to attentional strategies. Results indicated that the large majority of players reported using focus points that are consistent with an external focus of attention and that their thoughts corresponded to one or more categories related to technique, mental focus or concentration, general success, use of external focus cues, and emotional control. The findings are consistent with the view that experts may adopt complex attentional strategies that encompass both an external focus and thoughts about a variety of other performance related factors. PMID:27458419

  1. Self-Reported Responses to Player Profile Questions Show Consistency with the Use of Complex Attentional Strategies by Expert Horseshoe Pitchers.

    PubMed

    Fairbrother, Jeffrey T; Post, Phillip G; Whalen, Sam J

    2016-01-01

    The advantages on an external focus of attention have been demonstrated for a variety of sport tasks. The constrained action hypothesis (Wulf et al., 2001) argues that focusing externally on the movement effect results in the use of automated processes for movement control. In contrast, focusing internally in an attempt to control the movements of the body disrupts normally automated processes and degrades performance. Research on experts, however, suggests that they may adopt more complex attentional strategies. The present study provided a unique opportunity to examine expert horseshoe players' attentional strategies as indicated by their self-reported responses to questions included in a National Horseshoe Pitchers Association (NHPA) player profile questionnaire. Responses submitted by 83 top NHPA players were examined to determine the frequency of references to the use of internal and external focus points and identify categories related to attentional strategies. Results indicated that the large majority of players reported using focus points that are consistent with an external focus of attention and that their thoughts corresponded to one or more categories related to technique, mental focus or concentration, general success, use of external focus cues, and emotional control. The findings are consistent with the view that experts may adopt complex attentional strategies that encompass both an external focus and thoughts about a variety of other performance related factors. PMID:27458419

  2. HDF5-FastQuery: Accelerating Complex Queries on HDF Datasets usingFast Bitmap Indices

    SciTech Connect

    Gosink, Luke; Shalf, John; Stockinger, Kurt; Wu, Kesheng; Bethel,Wes

    2006-03-30

    Large scale scientific data is often stored in scientific data formats such as FITS, netCDF and HDF. These storage formats are of particular interest to the scientific user community since they provide multi-dimensional storage and retrieval. However, one of the drawbacks of these storage formats is that they do not support semantic indexing which is important for interactive data analysis where scientists look for features of interests such as ''Find all supernova explosions where energy > 10{sup 5} and temperature > 10{sup 6}''. In this paper we present a novel approach called HDF5-FastQuery to accelerate the data access of large HDF5 files by introducing multi-dimensional semantic indexing. Our implementation leverages an efficient indexing technology called bitmap indexing that has been widely used in the database community. Bitmap indices are especially well suited for interactive exploration of large-scale read only data. Storing the bitmap indices into the HDF5 file has the following advantages: (a) Significant performance speedup of accessing subsets of multi-dimensional data and (b) portability of the indices across multiple computer platforms. We will present an API that simplifies the execution of queries on HDF5 files for general scientific applications and data analysis. The design is flexible enough to accommodate the use of arbitrary indexing technology for semantic range queries. We will also provide a detailed performance analysis of HDF5-FastQuery for both synthetic and scientific data. The results demonstrate that our proposed approach for multi-dimensional queries is up to a factor of 2 faster than HDF5.

  3. HDF5-FastQuery: Accelerating Complex Queries on HDF Datasets UsingFast Bitmap Indices

    SciTech Connect

    Gosink, Luke; Shalf, John; Stockinger, Kurt; Wu, Kesheng; Bethel,Wes

    2005-12-07

    Large scale scientific data is often stored in scientific data formats such as FITS, netCDF and HDF. These storage formats are of particular interest to the scientific user community since they provide multi-dimensional storage and retrieval. However, one of the drawbacks of these storage formats is that they do not support semantic indexing which is important for interactive data analysis where scientists look for features of interests such as ''Find all supernova explosions where energy >105 and temperature >106''. In this paper we present a novel approach called HDF5-FastQuery to accelerate the data access of large HDF5 files by introducing multi-dimensional semantic indexing. Our implementation leverages an efficient indexing technology called ''bitmapindexing'' that has been widely used in the database community. Bitmapindices are especially well suited for interactive exploration of large-scale read-only data. Storing the bitmap indices into the HDF5 file has the following advantages: (a) Significant performance speedup of accessing subsets of multi-dimensional data and (b) portability of the indices across multiple computer platforms. We will present an API that simplifies the execution of queries on HDF5 files for general scientific applications and data analysis. The design is flexible enough to accommodate the use of arbitrary indexing technology for semantic range queries. We will also provide a detailed performance analysis of HDF5-FastQuery for both synthetic and scientific data. The results demonstrate that our proposed approach for multi-dimensional queries is up to a factor of 2 faster than HDF5.

  4. 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.

  5. 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.

  6. Single cell genome amplification accelerates identification of the apratoxin biosynthetic pathway from a complex microbial assemblage.

    PubMed

    Grindberg, Rashel V; Ishoey, Thomas; Brinza, Dumitru; Esquenazi, Eduardo; Coates, R Cameron; Liu, Wei-ting; Gerwick, Lena; Dorrestein, Pieter C; Pevzner, Pavel; Lasken, Roger; Gerwick, William H

    2011-04-12

    Filamentous marine cyanobacteria are extraordinarily rich sources of structurally novel, biomedically relevant natural products. To understand their biosynthetic origins as well as produce increased supplies and analog molecules, access to the clustered biosynthetic genes that encode for the assembly enzymes is necessary. Complicating these efforts is the universal presence of heterotrophic bacteria in the cell wall and sheath material of cyanobacteria obtained from the environment and those grown in uni-cyanobacterial culture. Moreover, the high similarity in genetic elements across disparate secondary metabolite biosynthetic pathways renders imprecise current gene cluster targeting strategies and contributes sequence complexity resulting in partial genome coverage. Thus, it was necessary to use a dual-method approach of single-cell genomic sequencing based on multiple displacement amplification (MDA) and metagenomic library screening. Here, we report the identification of the putative apratoxin. A biosynthetic gene cluster, a potent cancer cell cytotoxin with promise for medicinal applications. The roughly 58 kb biosynthetic gene cluster is composed of 12 open reading frames and has a type I modular mixed polyketide synthase/nonribosomal peptide synthetase (PKS/NRPS) organization and features loading and off-loading domain architecture never previously described. Moreover, this work represents the first successful isolation of a complete biosynthetic gene cluster from Lyngbya bouillonii, a tropical marine cyanobacterium renowned for its production of diverse bioactive secondary metabolites.

  7. Accelerated fluctuation analysis by graphic cards and complex pattern formation in financial markets

    NASA Astrophysics Data System (ADS)

    Preis, Tobias; Virnau, Peter; Paul, Wolfgang; Schneider, Johannes J.

    2009-09-01

    The compute unified device architecture is an almost conventional programming approach for managing computations on a graphics processing unit (GPU) as a data-parallel computing device. With a maximum number of 240 cores in combination with a high memory bandwidth, a recent GPU offers resources for computational physics. We apply this technology to methods of fluctuation analysis, which includes determination of the scaling behavior of a stochastic process and the equilibrium autocorrelation function. Additionally, the recently introduced pattern formation conformity (Preis T et al 2008 Europhys. Lett. 82 68005), which quantifies pattern-based complex short-time correlations of a time series, is calculated on a GPU and analyzed in detail. Results are obtained up to 84 times faster than on a current central processing unit core. When we apply this method to high-frequency time series of the German BUND future, we find significant pattern-based correlations on short time scales. Furthermore, an anti-persistent behavior can be found on short time scales. Additionally, we compare the recent GPU generation, which provides a theoretical peak performance of up to roughly 1012 floating point operations per second with the previous one. .

  8. The SM protein Sly1 accelerates assembly of the ER–Golgi SNARE complex

    PubMed Central

    Demircioglu, F. Esra; Burkhardt, Pawel; Fasshauer, Dirk

    2014-01-01

    Soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) and Sec1/Munc18 (SM) proteins constitute the core of an ancient vesicle fusion machine that diversified into distinct sets that now function in different trafficking steps in eukaryotic cells. Deciphering their precise mode of action has proved challenging. SM proteins are thought to act primarily through one type of SNARE protein, the syntaxins. Despite high structural similarity, however, contrasting binding modes have been found for different SM proteins and syntaxins. Whereas the secretory SM protein Munc18 binds to the ‟closed conformation” of syntaxin 1, the ER–Golgi SM protein Sly1 interacts only with the N-peptide of Sed5. Recent findings, however, indicate that SM proteins might interact simultaneously with both syntaxin regions. In search for a common mechanism, we now reinvestigated the Sly1/Sed5 interaction. We found that individual Sed5 adopts a tight closed conformation. Sly1 binds to both the closed conformation and the N-peptide of Sed5, suggesting that this is the original binding mode of SM proteins and syntaxins. In contrast to Munc18, however, Sly1 facilitates SNARE complex formation by loosening the closed conformation of Sed5. PMID:25189771

  9. The SM protein Sly1 accelerates assembly of the ER-Golgi SNARE complex.

    PubMed

    Demircioglu, F Esra; Burkhardt, Pawel; Fasshauer, Dirk

    2014-09-23

    Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) and Sec1/Munc18 (SM) proteins constitute the core of an ancient vesicle fusion machine that diversified into distinct sets that now function in different trafficking steps in eukaryotic cells. Deciphering their precise mode of action has proved challenging. SM proteins are thought to act primarily through one type of SNARE protein, the syntaxins. Despite high structural similarity, however, contrasting binding modes have been found for different SM proteins and syntaxins. Whereas the secretory SM protein Munc18 binds to the ‟closed conformation" of syntaxin 1, the ER-Golgi SM protein Sly1 interacts only with the N-peptide of Sed5. Recent findings, however, indicate that SM proteins might interact simultaneously with both syntaxin regions. In search for a common mechanism, we now reinvestigated the Sly1/Sed5 interaction. We found that individual Sed5 adopts a tight closed conformation. Sly1 binds to both the closed conformation and the N-peptide of Sed5, suggesting that this is the original binding mode of SM proteins and syntaxins. In contrast to Munc18, however, Sly1 facilitates SNARE complex formation by loosening the closed conformation of Sed5.

  10. A workflow for transferring heterogeneous complex geological models to consistent finite element models and application to a deep geothermal reservoir operation

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Bauer, Sebastian

    2016-04-01

    Geological models are the prerequisite of exploring possible use of the subsurface and evaluating induced impacts. Subsurface geological models often show strong complexity in geometry and hydraulic connectivity because of their heterogeneous nature. In order to model that complexity, the corner point grid approach has been applied by geologists for decades. The corner point grid utilizes a set of hexahedral blocks to represent geological formations. Due to the appearance of eroded geological layers, some edges of those blocks may be collapsed and the blocks thus degenerate. This leads to the inconsistency and the impossibility of using the corner point grid directly with a finite element based simulator. Therefore, in this study, we introduce a workflow for transferring heterogeneous geological models to consistent finite element models. In the corner point grid, the hexahedral blocks without collapsed edges are converted to hexahedral elements directly. But if they degenerate, each block is divided into prism, pyramid and tetrahedral elements based on individual degenerated situation. This approach consistently converts any degenerated corner point grid to a consistent hybrid finite element mesh. Along with the above converting scheme, the corresponding heterogeneous geological data, e.g. permeability and porosity, can be transferred as well. Moreover, well trajectories designed in the corner point grid can be resampled to the nodes in the finite element mesh, which represents the location for source terms along the well path. As a proof of concept, we implement the workflow in the framework of transferring models from Petrel to the finite element OpenGeoSys simulator. As application scenario we choose a deep geothermal reservoir operation in the North German Basin. A well doublet is defined in a saline aquifer in the Rhaetian formation, which has a depth of roughly 4000 m. The geometric model shows all kinds of degenerated blocks due to eroded layers and the

  11. Structural insights into how Yrb2p accelerates the assembly of the Xpo1p nuclear export complex.

    PubMed

    Koyama, Masako; Shirai, Natsuki; Matsuura, Yoshiyuki

    2014-11-01

    Proteins and ribonucleoproteins containing a nuclear export signal (NES) assemble with the exportin Xpo1p (yeast CRM1) and Gsp1p-GTP (yeast Ran-GTP) in the nucleus and exit through the nuclear pore complex. In the cytoplasm, Yrb1p (yeast RanBP1) displaces NES from Xpo1p. Efficient export of NES-cargoes requires Yrb2p (yeast RanBP3), a primarily nuclear protein containing nucleoporin-like phenylalanine-glycine (FG) repeats and a low-affinity Gsp1p-binding domain (RanBD). Here, we show that Yrb2p strikingly accelerates the association of Gsp1p-GTP and NES to Xpo1p. We have solved the crystal structure of the Xpo1p-Yrb2p-Gsp1p-GTP complex, a key assembly intermediate that can bind cargo rapidly. Although the NES-binding cleft of Xpo1p is closed in this intermediate, our data suggest that preloading of Gsp1p-GTP onto Xpo1p by Yrb2p, conformational flexibility of Xpo1p, and the low affinity of RanBD enable active displacement of Yrb2p RanBD by NES to occur effectively. The structure also reveals the major binding sites for FG repeats on Xpo1p.

  12. Assessment and acceleration of binding energy calculations for protein-ligand complexes by the fragment molecular orbital method.

    PubMed

    Otsuka, Takao; Okimoto, Noriaki; Taiji, Makoto

    2015-11-15

    In the field of drug discovery, it is important to accurately predict the binding affinities between target proteins and drug applicant molecules. Many of the computational methods available for evaluating binding affinities have adopted molecular mechanics-based force fields, although they cannot fully describe protein-ligand interactions. A noteworthy computational method in development involves large-scale electronic structure calculations. Fragment molecular orbital (FMO) method, which is one of such large-scale calculation techniques, is applied in this study for calculating the binding energies between proteins and ligands. By testing the effects of specific FMO calculation conditions (including fragmentation size, basis sets, electron correlation, exchange-correlation functionals, and solvation effects) on the binding energies of the FK506-binding protein and 10 ligand complex molecule, we have found that the standard FMO calculation condition, FMO2-MP2/6-31G(d), is suitable for evaluating the protein-ligand interactions. The correlation coefficient between the binding energies calculated with this FMO calculation condition and experimental values is determined to be R = 0.77. Based on these results, we also propose a practical scheme for predicting binding affinities by combining the FMO method with the quantitative structure-activity relationship (QSAR) model. The results of this combined method can be directly compared with experimental binding affinities. The FMO and QSAR combined scheme shows a higher correlation with experimental data (R = 0.91). Furthermore, we propose an acceleration scheme for the binding energy calculations using a multilayer FMO method focusing on the protein-ligand interaction distance. Our acceleration scheme, which uses FMO2-HF/STO-3G:MP2/6-31G(d) at R(int) = 7.0 Å, reduces computational costs, while maintaining accuracy in the evaluation of binding energy.

  13. LINEAR ACCELERATOR

    DOEpatents

    Colgate, S.A.

    1958-05-27

    An improvement is presented in linear accelerators for charged particles with respect to the stable focusing of the particle beam. The improvement consists of providing a radial electric field transverse to the accelerating electric fields and angularly introducing the beam of particles in the field. The results of the foregoing is to achieve a beam which spirals about the axis of the acceleration path. The combination of the electric fields and angular motion of the particles cooperate to provide a stable and focused particle beam.

  14. Investigation of induced radioactivity in the Linac-Adone accelerator complex for the management of the decommissioned material.

    PubMed

    Mora, Juan Carlos; Bedogni, Roberto; Esposito, Adolfo; Cancio, David

    2007-03-01

    The LINAC-ADONE accelerator complex of the INFN-LNF Frascati National Laboratories, operating for 27 y prior to the commissioning of DAPhiNE, was dismantled in 1993. The scraps resulting from the decommissioning of LINAC-ADPhiNE have been temporarily stored in the same Frascati laboratory, waiting for definitive disposal. Relying on recommendations of the IAEA, European Commission and Italian committees, an experimental characterization study of the LNF repository was performed. The main objective was a classification of the scraps on the basis of internationally recognized "clearance levels," which are 0.1 Bq g(-1) for the isotopes of interest for this work. Secondly, a measurement of the materials suspected to be above 0.1 Bq g(-1) was planned. Activation isotopes were expected from the aluminum, copper, steel, and iron of the LINAC and the ADONE ring sections. For screening purposes, the repository area has been divided into zones, where in-situ measurements with a portable HP-Ge detector have been performed. In addition, small samples have been cut from a representative number of pieces, and accurate laboratory measurements have been made with a low background HP-Ge spectrometer. The experimental results are in good agreement with other studies and show that a large part of the material is below the mentioned specific activity level.

  15. Investigation of induced radioactivity in the Linac-Adone accelerator complex for the management of the decommissioned material.

    PubMed

    Mora, Juan Carlos; Bedogni, Roberto; Esposito, Adolfo; Cancio, David

    2007-03-01

    The LINAC-ADONE accelerator complex of the INFN-LNF Frascati National Laboratories, operating for 27 y prior to the commissioning of DAPhiNE, was dismantled in 1993. The scraps resulting from the decommissioning of LINAC-ADPhiNE have been temporarily stored in the same Frascati laboratory, waiting for definitive disposal. Relying on recommendations of the IAEA, European Commission and Italian committees, an experimental characterization study of the LNF repository was performed. The main objective was a classification of the scraps on the basis of internationally recognized "clearance levels," which are 0.1 Bq g(-1) for the isotopes of interest for this work. Secondly, a measurement of the materials suspected to be above 0.1 Bq g(-1) was planned. Activation isotopes were expected from the aluminum, copper, steel, and iron of the LINAC and the ADONE ring sections. For screening purposes, the repository area has been divided into zones, where in-situ measurements with a portable HP-Ge detector have been performed. In addition, small samples have been cut from a representative number of pieces, and accurate laboratory measurements have been made with a low background HP-Ge spectrometer. The experimental results are in good agreement with other studies and show that a large part of the material is below the mentioned specific activity level. PMID:17293695

  16. Fc-based delivery system enhances immunogenicity of a tuberculosis subunit vaccine candidate consisting of the ESAT-6:CFP-10 complex.

    PubMed

    Farsiani, Hadi; Mosavat, Arman; Soleimanpour, Saman; Sadeghian, Hamid; Akbari Eydgahi, Mohammad Reza; Ghazvini, Kiarash; Sankian, Mojtaba; Aryan, Ehsan; Jamehdar, Saeid Amel; Rezaee, Seyed Abdolrahim

    2016-06-21

    Tuberculosis (TB) remains a major global health threat despite chemotherapy and Bacilli Calmette-Guérin (BCG) vaccination. Therefore, a safer and more effective vaccine against TB is urgently needed. This study evaluated the immunogenicity of a recombinant fusion protein consisting of early secreted antigenic target protein 6 kDa (ESAT-6), culture filtrate protein 10 kDa (CFP-10) and the Fc-domain of mouse IgG2a as a novel subunit vaccine. The recombinant expression vectors (pPICZαA-ESAT-6:CFP-10:Fcγ2a and pPICZαA-ESAT-6:CFP-10:His) were transferred into Pichia pastoris. After SDS-PAGE and immunoblotting, the immunogenicity of the recombinant proteins was evaluated in mice. When both recombinant proteins (ESAT-6:CFP-10:Fcγ2a and ESAT-6:CFP-10:His) were used for vaccination, Th1-type cellular responses were induced producing high levels of IFN-γ and IL-12. However, the Fc-tagged recombinant protein induced more effective Th1-type cellular responses with a small increase in IL-4 as compared to the BCG and ESAT-6:CFP-10:His groups. Moreover, mice primed with BCG and then supplemented with ESAT-6:CFP-10:Fcγ2a produced the highest levels of IFN-γ and IL-12 in immunized groups. The findings indicate that when Fcγ2a is fused to the ESAT-6:CFP-10 complex, as a delivery vehicle, there could be an increase in the immunogenicity of this type of subunit vaccine. Therefore, additional investigations are necessary for the development of appropriate Fc-based tuberculosis vaccines. PMID:27138226

  17. Analytical gradients of complete active space self-consistent field energies using Cholesky decomposition: Geometry optimization and spin-state energetics of a ruthenium nitrosyl complex

    SciTech Connect

    Delcey, Mickaël G.; Freitag, Leon; González, Leticia; Pedersen, Thomas Bondo; Aquilante, Francesco; Lindh, Roland

    2014-05-07

    We present a formulation of analytical energy gradients at the complete active space self-consistent field (CASSCF) level of theory employing density fitting (DF) techniques to enable efficient geometry optimizations of large systems. As an example, the ground and lowest triplet state geometries of a ruthenium nitrosyl complex are computed at the DF-CASSCF level of theory and compared with structures obtained from density functional theory (DFT) using the B3LYP, BP86, and M06L functionals. The average deviation of all bond lengths compared to the crystal structure is 0.042 Å at the DF-CASSCF level of theory, which is slightly larger but still comparable with the deviations obtained by the tested DFT functionals, e.g., 0.032 Å with M06L. Specifically, the root-mean-square deviation between the DF-CASSCF and best DFT coordinates, delivered by BP86, is only 0.08 Å for S{sub 0} and 0.11 Å for T{sub 1}, indicating that the geometries are very similar. While keeping the mean energy gradient errors below 0.25%, the DF technique results in a 13-fold speedup compared to the conventional CASSCF geometry optimization algorithm. Additionally, we assess the singlet-triplet energy vertical and adiabatic differences with multiconfigurational second-order perturbation theory (CASPT2) using the DF-CASSCF and DFT optimized geometries. It is found that the vertical CASPT2 energies are relatively similar regardless of the geometry employed whereas the adiabatic singlet-triplet gaps are more sensitive to the chosen triplet geometry.

  18. The Spallation Neutron Source accelerator system design

    NASA Astrophysics Data System (ADS)

    Henderson, S.; Abraham, W.; Aleksandrov, A.; Allen, C.; Alonso, J.; Anderson, D.; Arenius, D.; Arthur, T.; Assadi, S.; Ayers, J.; Bach, P.; Badea, V.; Battle, R.; Beebe-Wang, J.; Bergmann, B.; Bernardin, J.; Bhatia, T.; Billen, J.; Birke, T.; Bjorklund, E.; Blaskiewicz, M.; Blind, B.; Blokland, W.; Bookwalter, V.; Borovina, D.; Bowling, S.; Bradley, J.; Brantley, C.; Brennan, J.; Brodowski, J.; Brown, S.; Brown, R.; Bruce, D.; Bultman, N.; Cameron, P.; Campisi, I.; Casagrande, F.; Catalan-Lasheras, N.; Champion, M.; Champion, M.; Chen, Z.; Cheng, D.; Cho, Y.; Christensen, K.; Chu, C.; Cleaves, J.; Connolly, R.; Cote, T.; Cousineau, S.; Crandall, K.; Creel, J.; Crofford, M.; Cull, P.; Cutler, R.; Dabney, R.; Dalesio, L.; Daly, E.; Damm, R.; Danilov, V.; Davino, D.; Davis, K.; Dawson, C.; Day, L.; Deibele, C.; Delayen, J.; DeLong, J.; Demello, A.; DeVan, W.; Digennaro, R.; Dixon, K.; Dodson, G.; Doleans, M.; Doolittle, L.; Doss, J.; Drury, M.; Elliot, T.; Ellis, S.; Error, J.; Fazekas, J.; Fedotov, A.; Feng, P.; Fischer, J.; Fox, W.; Fuja, R.; Funk, W.; Galambos, J.; Ganni, V.; Garnett, R.; Geng, X.; Gentzlinger, R.; Giannella, M.; Gibson, P.; Gillis, R.; Gioia, J.; Gordon, J.; Gough, R.; Greer, J.; Gregory, W.; Gribble, R.; Grice, W.; Gurd, D.; Gurd, P.; Guthrie, A.; Hahn, H.; Hardek, T.; Hardekopf, R.; Harrison, J.; Hatfield, D.; He, P.; Hechler, M.; Heistermann, F.; Helus, S.; Hiatt, T.; Hicks, S.; Hill, J.; Hill, J.; Hoff, L.; Hoff, M.; Hogan, J.; Holding, M.; Holik, P.; Holmes, J.; Holtkamp, N.; Hovater, C.; Howell, M.; Hseuh, H.; Huhn, A.; Hunter, T.; Ilg, T.; Jackson, J.; Jain, A.; Jason, A.; Jeon, D.; Johnson, G.; Jones, A.; Joseph, S.; Justice, A.; Kang, Y.; Kasemir, K.; Keller, R.; Kersevan, R.; Kerstiens, D.; Kesselman, M.; Kim, S.; Kneisel, P.; Kravchuk, L.; Kuneli, T.; Kurennoy, S.; Kustom, R.; Kwon, S.; Ladd, P.; Lambiase, R.; Lee, Y. Y.; Leitner, M.; Leung, K.-N.; Lewis, S.; Liaw, C.; Lionberger, C.; Lo, C. C.; Long, C.; Ludewig, H.; Ludvig, J.; Luft, P.; Lynch, M.; Ma, H.; MacGill, R.; Macha, K.; Madre, B.; Mahler, G.; Mahoney, K.; Maines, J.; Mammosser, J.; Mann, T.; Marneris, I.; Marroquin, P.; Martineau, R.; Matsumoto, K.; McCarthy, M.; McChesney, C.; McGahern, W.; McGehee, P.; Meng, W.; Merz, B.; Meyer, R.; Meyer, R.; Miller, B.; Mitchell, R.; Mize, J.; Monroy, M.; Munro, J.; Murdoch, G.; Musson, J.; Nath, S.; Nelson, R.; Nelson, R.; O`Hara, J.; Olsen, D.; Oren, W.; Oshatz, D.; Owens, T.; Pai, C.; Papaphilippou, I.; Patterson, N.; Patterson, J.; Pearson, C.; Pelaia, T.; Pieck, M.; Piller, C.; Plawski, T.; Plum, M.; Pogge, J.; Power, J.; Powers, T.; Preble, J.; Prokop, M.; Pruyn, J.; Purcell, D.; Rank, J.; Raparia, D.; Ratti, A.; Reass, W.; Reece, K.; Rees, D.; Regan, A.; Regis, M.; Reijonen, J.; Rej, D.; Richards, D.; Richied, D.; Rode, C.; Rodriguez, W.; Rodriguez, M.; Rohlev, A.; Rose, C.; Roseberry, T.; Rowton, L.; Roybal, W.; Rust, K.; Salazer, G.; Sandberg, J.; Saunders, J.; Schenkel, T.; Schneider, W.; Schrage, D.; Schubert, J.; Severino, F.; Shafer, R.; Shea, T.; Shishlo, A.; Shoaee, H.; Sibley, C.; Sims, J.; Smee, S.; Smith, J.; Smith, K.; Spitz, R.; Staples, J.; Stein, P.; Stettler, M.; Stirbet, M.; Stockli, M.; Stone, W.; Stout, D.; Stovall, J.; Strelo, W.; Strong, H.; Sundelin, R.; Syversrud, D.; Szajbler, M.; Takeda, H.; Tallerico, P.; Tang, J.; Tanke, E.; Tepikian, S.; Thomae, R.; Thompson, D.; Thomson, D.; Thuot, M.; Treml, C.; Tsoupas, N.; Tuozzolo, J.; Tuzel, W.; Vassioutchenko, A.; Virostek, S.; Wallig, J.; Wanderer, P.; Wang, Y.; Wang, J. G.; Wangler, T.; Warren, D.; Wei, J.; Weiss, D.; Welton, R.; Weng, J.; Weng, W.-T.; Wezensky, M.; White, M.; Whitlatch, T.; Williams, D.; Williams, E.; Wilson, K.; Wiseman, M.; Wood, R.; Wright, P.; Wu, A.; Ybarrolaza, N.; Young, K.; Young, L.; Yourd, R.; Zachoszcz, A.; Zaltsman, A.; Zhang, S.; Zhang, W.; Zhang, Y.; Zhukov, A.

    2014-11-01

    The Spallation Neutron Source (SNS) was designed and constructed by a collaboration of six U.S. Department of Energy national laboratories. The SNS accelerator system consists of a 1 GeV linear accelerator and an accumulator ring providing 1.4 MW of proton beam power in microsecond-long beam pulses to a liquid mercury target for neutron production. The accelerator complex consists of a front-end negative hydrogen-ion injector system, an 87 MeV drift tube linear accelerator, a 186 MeV side-coupled linear accelerator, a 1 GeV superconducting linear accelerator, a 248-m circumference accumulator ring and associated beam transport lines. The accelerator complex is supported by ~100 high-power RF power systems, a 2 K cryogenic plant, ~400 DC and pulsed power supply systems, ~400 beam diagnostic devices and a distributed control system handling ~100,000 I/O signals. The beam dynamics design of the SNS accelerator is presented, as is the engineering design of the major accelerator subsystems.

  19. Lazy arc consistency

    SciTech Connect

    Schiex, T.; Gaspin, C.; Regin, J.C.; Verfaillie, G.

    1996-12-31

    Arc consistency filtering is widely used in the framework of binary constraint satisfaction problems: with a low complexity, inconsistency may be detected and domains are filtered. In this paper, we show that when detecting inconsistency is the objective, a systematic domain filtering is useless and a lazy approach is more adequate. Whereas usual arc consistency algorithms produce the maximum arc consistent sub-domain, when it exists, we propose a method, called LAC{tau}, which only looks for any arc consistent sub-domain. The algorithm is then extended to provide the additional service of locating one variable with a minimum domain cardinality in the maximum arc consistent sub-domain, without necessarily computing all domain sizes. Finally, we compare traditional AC enforcing and lazy AC enforcing using several benchmark problems, both randomly generated CSP and real life problems.

  20. Highly Effective Non-Viral Antitumor Gene Therapy System Comprised of Biocompatible Small Plasmid Complex Particles Consisting of pDNA, Anionic Polysaccharide, and Fully Deprotected Linear Polyethylenimine.

    PubMed

    Koyama, Yoshiyuki; Sugiura, Kikuya; Yoshihara, Chieko; Inaba, Toshio; Ito, Tomoko

    2015-07-23

    We have reported that ternary complexes of plasmid DNA with conventional linear polyethylenimine (l-PEI) and certain polyanions were very stably dispersed, and, with no cryoprotectant, they could be freeze-dried and re-hydrated without the loss of transfection ability. These properties enabled the preparation of a concentrated suspension of very small pDNA complex, by preparing the complexes at highly diluted conditions, followed by condensation via lyophilization-and-rehydration procedure. Recently, a high potency linear polyethylenimine having no residual protective groups, i.e., Polyethylenimine "Max" (PEI "Max"), is available, which has been reported to induce much higher gene expression than conventional l-PEI. We tried to prepare the small DNA/PEI "Max"/polyanion complexes by a similar freeze-drying method. Small complex particles could be obtained without apparent aggregation, but transfection activity of the rehydrated complexes was severely reduced. Complex-preparation conditions were investigated in details to achieve the freeze-dried DNA/PEI "Max"/polyanion small ternary complexes with high transfection efficiency. DNA/PEI "Max"/polyanion complexes containing cytokine-coding plasmids were then prepared, and their anti-tumor therapeutic efficacy was examined in tumor-bearing mice.

  1. Highly Effective Non-Viral Antitumor Gene Therapy System Comprised of Biocompatible Small Plasmid Complex Particles Consisting of pDNA, Anionic Polysaccharide, and Fully Deprotected Linear Polyethylenimine

    PubMed Central

    Koyama, Yoshiyuki; Sugiura, Kikuya; Yoshihara, Chieko; Inaba, Toshio; Ito, Tomoko

    2015-01-01

    We have reported that ternary complexes of plasmid DNA with conventional linear polyethylenimine (l-PEI) and certain polyanions were very stably dispersed, and, with no cryoprotectant, they could be freeze-dried and re-hydrated without the loss of transfection ability. These properties enabled the preparation of a concentrated suspension of very small pDNA complex, by preparing the complexes at highly diluted conditions, followed by condensation via lyophilization-and-rehydration procedure. Recently, a high potency linear polyethylenimine having no residual protective groups, i.e., Polyethylenimine “Max” (PEI “Max”), is available, which has been reported to induce much higher gene expression than conventional l-PEI. We tried to prepare the small DNA/PEI “Max”/polyanion complexes by a similar freeze-drying method. Small complex particles could be obtained without apparent aggregation, but transfection activity of the rehydrated complexes was severely reduced. Complex-preparation conditions were investigated in details to achieve the freeze-dried DNA/PEI “Max”/polyanion small ternary complexes with high transfection efficiency. DNA/PEI “Max”/polyanion complexes containing cytokine-coding plasmids were then prepared, and their anti-tumor therapeutic efficacy was examined in tumor-bearing mice. PMID:26213961

  2. Multidimensional earthquake frequency distributions consistent with self-organization of complex systems: The interdependence of magnitude, interevent time and interevent distance

    NASA Astrophysics Data System (ADS)

    Tzanis, A.; Vallianatos, F.

    2012-04-01

    It is well known that earthquake frequency is related to earthquake magnitude via a simple linear relationship of the form logN = a - bM, where N is the number of earthquakes in a specified time interval; this is the famous Gutenberg - Richter (G-R) law. The generally accepted interpretation of the G-R law is that it expresses the statistical behaviour of a fractal active tectonic grain (active faulting) - the relationship between the constant b and the fractal dimension of the tectonic grain has been demonstrated in various ways. The story told by the G-R law is, nevertheless, incomplete! It is now accepted that the active tectonic grain comprises a critical complex system, although it hasn't yet been established whether it is stationary (Self-Organized Critical), evolutionary (Self-Organizing Critical), or a time-varying blend of both. At any rate, critical systems are characterized by strong interactions between near and distant neighbours. This, in turn, implies that the self-organization of earthquake occurrence should be manifested by certain statistical behaviour of its temporal and spatial dependence. A measure of temporal dependence is the time lapsed between consecutive events above a magnitude threshold over a given area (interevent time). A measure of spatial dependence is the hypocentral distance between consecutive events above a magnitude threshold over a given area (interevent distance). The statistics of earthquake frequency - interevent times have been studied by several researchers, albeit frequently on the basis of different definition for the interevent time. The statistics of earthquake frequency - interevent distance is still terra incognita. Herein we present a multidimensional analysis of the statistical behaviour of frequency - magnitude - interevent time, frequency - magnitude - interevent distance and frequency - interevent time - interevent distance. We demonstrate that earthquake frequency is multiply related, not only to magnitude as

  3. Can Multiconfigurational Self-Consistent Field Theory and Density Functional Theory Correctly Predict the Ground State of Metal-Metal-Bonded Complexes?

    PubMed

    Carlson, Rebecca K; Odoh, Samuel O; Tereniak, Stephen J; Lu, Connie C; Gagliardi, Laura

    2015-09-01

    The electronic structure of a diiron (FeFe) complex with strong metal-metal interaction and those of analogous complexes (CoCo, CoMn, CoFe, and FeMn) with much weaker metal-metal bonding are investigated with wave function-based methods and density functional theory. The delocalization and bonding between the metal centers in the diiron complex is only fully captured after inclusion of the complete set of 3d and 4d orbitals in the active space, a situation best suited for restricted active space (RAS) approaches. Truncation of the included set of 4d orbitals results in inappropriate localization of some 3d orbitals, incorrect description of the ground spin state as well as wrong spin state energetics, as compared to experiment. Using density functional theory, some local functionals are able to predict the correct ground spin states, and describe the chemical bonding and structural properties of all the metal-metal complexes considered in this work. In contrast, the introduction of some exact exchange results in increased localization of 3d orbitals and wrong spin state energetics, a situation that is particularly troublesome for the diiron complex.

  4. Aligning "TextEvaluator"® Scores with the Accelerated Text Complexity Guidelines Specified in the Common Core State Standards. Research Report. ETS RR-15-21

    ERIC Educational Resources Information Center

    Sheehan, Kathleen M.

    2015-01-01

    The "TextEvaluator"® text analysis tool is a fully automated text complexity evaluation tool designed to help teachers, curriculum specialists, textbook publishers, and test developers select texts that are consistent with the text complexity guidelines specified in the Common Core State Standards.This paper documents the procedure used…

  5. Novel hybrid organic thermoelectric materials:three-component hybrid films consisting of a nanoparticle polymer complex, carbon nanotubes, and vinyl polymer.

    PubMed

    Toshima, Naoki; Oshima, Keisuke; Anno, Hiroaki; Nishinaka, Takahiko; Ichikawa, Shoko; Iwata, Arihiro; Shiraishi, Yukihide

    2015-04-01

    A novel class of hybrid organic thermoelectric materials is demonstrated for the first time for constructing flexible thermoelectric devices on polyimide substrates with high output power by using nanotechnology instead of conducting polymers such as poly(3,4-ethylenedioxythiophene). The hybrid organic thermoelectric materials are composed of nanoparticles of a polymer complex, carbon nanotubes, and poly(vinyl chloride), and show high performance (dimensionless thermoelectric figure-of-merit, ZT ≈ 0.3, based on the thermal conductivity through the film).

  6. The direction of acceleration

    NASA Astrophysics Data System (ADS)

    Wilhelm, Thomas; Burde, Jan-Philipp; Lück, Stephan

    2015-11-01

    Acceleration is a physical quantity that is difficult to understand and hence its complexity is often erroneously simplified. Many students think of acceleration as equivalent to velocity, a ˜ v. For others, acceleration is a scalar quantity, which describes the change in speed Δ|v| or Δ|v|/Δt (as opposed to the change in velocity). The main difficulty with the concept of acceleration therefore lies in developing a correct understanding of its direction. The free iOS app AccelVisu supports students in acquiring a correct conception of acceleration by showing acceleration arrows directly at moving objects.

  7. Nature-Inspired, Highly Durable CO2 Reduction System Consisting of a Binuclear Ruthenium(II) Complex and an Organic Semiconductor Using Visible Light.

    PubMed

    Kuriki, Ryo; Matsunaga, Hironori; Nakashima, Takuya; Wada, Keisuke; Yamakata, Akira; Ishitani, Osamu; Maeda, Kazuhiko

    2016-04-20

    A metal-free organic semiconductor of mesoporous graphitic carbon nitride (C3N4) coupled with a Ru(II) binuclear complex (RuRu') containing photosensitizer and catalytic units selectively reduced CO2 into HCOOH under visible light (λ > 400 nm) in the presence of a suitable electron donor with high durability, even in aqueous solution. Modification of C3N4 with Ag nanoparticles resulted in a RuRu'/Ag/C3N4 photocatalyst that exhibited a very high turnover number (>33000 with respect to the amount of RuRu'), while maintaining high selectivity for HCOOH production (87-99%). This turnover number was 30 times greater than that reported previously using C3N4 modified with a mononuclear Ru(II) complex, and by far the highest among the metal-complex/semiconductor hybrid systems reported to date. The results of photocatalytic reactions, emission decay measurements, and time-resolved infrared spectroscopy indicated that Ag nanoparticles on C3N4 collected electrons having lifetimes of several milliseconds from the conduction band of C3N4, which were transferred to the excited state of RuRu', thereby promoting photocatalytic CO2 reduction driven by two-step photoexcitation of C3N4 and RuRu'. This study also revealed that the RuRu'/Ag/C3N4 hybrid photocatalyst worked efficiently in water containing a proper electron donor, despite the intrinsic hydrophobic nature of C3N4 and low solubility of CO2 in an aqueous environment.

  8. A Sensory Complex Consisting of an ATP-binding Cassette Transporter and a Two-component Regulatory System Controls Bacitracin Resistance in Bacillus subtilis*

    PubMed Central

    Dintner, Sebastian; Heermann, Ralf; Fang, Chong; Jung, Kirsten; Gebhard, Susanne

    2014-01-01

    Resistance against antimicrobial peptides in many Firmicutes bacteria is mediated by detoxification systems that are composed of a two-component regulatory system (TCS) and an ATP-binding cassette (ABC) transporter. The histidine kinases of these systems depend entirely on the transporter for sensing of antimicrobial peptides, suggesting a novel mode of signal transduction where the transporter constitutes the actual sensor. The aim of this study was to investigate the molecular mechanisms of this unusual signaling pathway in more detail, using the bacitracin resistance system BceRS-BceAB of Bacillus subtilis as an example. To analyze the proposed communication between TCS and the ABC transporter, we characterized their interactions by bacterial two-hybrid analyses and could show that the permease BceB and the histidine kinase BceS interact directly. In vitro pulldown assays confirmed this interaction, which was found to be independent of bacitracin. Because it was unknown whether BceAB-type transporters could detect their substrate peptides directly or instead recognized the peptide-target complex in the cell envelope, we next analyzed substrate binding by the transport permease, BceB. Direct and specific binding of bacitracin by BceB was demonstrated by surface plasmon resonance spectroscopy. Finally, in vitro signal transduction assays indicated that complex formation with the transporter influenced the autophosphorylation activity of the histidine kinase. Taken together, our findings clearly show the existence of a sensory complex composed of TCS and ABC transporters and provide the first functional insights into the mechanisms of stimulus perception, signal transduction, and antimicrobial resistance employed by Bce-like detoxification systems. PMID:25118291

  9. Acceleration of Monte Carlo simulation of photon migration in complex heterogeneous media using Intel many-integrated core architecture.

    PubMed

    Gorshkov, Anton V; Kirillin, Mikhail Yu

    2015-08-01

    Over two decades, the Monte Carlo technique has become a gold standard in simulation of light propagation in turbid media, including biotissues. Technological solutions provide further advances of this technique. The Intel Xeon Phi coprocessor is a new type of accelerator for highly parallel general purpose computing, which allows execution of a wide range of applications without substantial code modification. We present a technical approach of porting our previously developed Monte Carlo (MC) code for simulation of light transport in tissues to the Intel Xeon Phi coprocessor. We show that employing the accelerator allows reducing computational time of MC simulation and obtaining simulation speed-up comparable to GPU. We demonstrate the performance of the developed code for simulation of light transport in the human head and determination of the measurement volume in near-infrared spectroscopy brain sensing. PMID:26249663

  10. Multi-electron oxygen reduction by a hybrid visible-light-photocatalyst consisting of metal-oxide semiconductor and self-assembled biomimetic complex.

    PubMed

    Naya, Shin-ichi; Niwa, Tadahiro; Negishi, Ryo; Kobayashi, Hisayoshi; Tada, Hiroaki

    2014-12-01

    Adsorption experiments and density functional theory (DFT) simulations indicated that Cu(acac)2 is chemisorbed on the monoclinic sheelite (ms)-BiVO4 surface to form an O2-bridged binuclear complex (OBBC/BiVO4) like hemocyanin. Multi-electron reduction of O2 is induced by the visible-light irradiation of the OBBC/BiVO4 in the same manner as a blue Cu enzyme. The drastic enhancement of the O2 reduction renders ms-BiVO4 to work as a good visible-light photocatalyst without any sacrificial reagents. As a model reaction, we show that this biomimetic hybrid photocatalyst exhibits a high level of activity for the aerobic oxidation of amines to aldehydes in aqueous solution and imines in THF solution at 25 °C giving selectivities above 99% under visible-light irradiation.

  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. Are there consistent grazing indicators in Drylands? Testing plant functional types of various complexity in South Africa's Grassland and Savanna Biomes.

    PubMed

    Linstädter, Anja; Schellberg, Jürgen; Brüser, Katharina; Moreno García, Cristian A; Oomen, Roelof J; du Preez, Chris C; Ruppert, Jan C; Ewert, Frank

    2014-01-01

    Despite our growing knowledge on plants' functional responses to grazing, there is no consensus if an optimum level of functional aggregation exists for detecting grazing effects in drylands. With a comparative approach we searched for plant functional types (PFTs) with a consistent response to grazing across two areas differing in climatic aridity, situated in South Africa's grassland and savanna biomes. We aggregated herbaceous species into PFTs, using hierarchical combinations of traits (from single- to three-trait PFTs). Traits relate to life history, growth form and leaf width. We first confirmed that soil and grazing gradients were largely independent from each other, and then searched in each biome for PFTs with a sensitive response to grazing, avoiding confounding with soil conditions. We found no response consistency, but biome-specific optimum aggregation levels. Three-trait PFTs (e.g. broad-leaved perennial grasses) and two-trait PFTs (e.g. perennial grasses) performed best as indicators of grazing effects in the semi-arid grassland and in the arid savanna biome, respectively. Some PFTs increased with grazing pressure in the grassland, but decreased in the savanna. We applied biome-specific grazing indicators to evaluate if differences in grazing management related to land tenure (communal versus freehold) had effects on vegetation. Tenure effects were small, which we mainly attributed to large variability in grazing pressure across farms. We conclude that the striking lack of generalizable PFT responses to grazing is due to a convergence of aridity and grazing effects, and unlikely to be overcome by more refined classification approaches. Hence, PFTs with an opposite response to grazing in the two biomes rather have a unimodal response along a gradient of additive forces of aridity and grazing. The study advocates for hierarchical trait combinations to identify localized indicator sets for grazing effects. Its methodological approach may also be useful

  13. Are there consistent grazing indicators in Drylands? Testing plant functional types of various complexity in South Africa's Grassland and Savanna Biomes.

    PubMed

    Linstädter, Anja; Schellberg, Jürgen; Brüser, Katharina; Moreno García, Cristian A; Oomen, Roelof J; du Preez, Chris C; Ruppert, Jan C; Ewert, Frank

    2014-01-01

    Despite our growing knowledge on plants' functional responses to grazing, there is no consensus if an optimum level of functional aggregation exists for detecting grazing effects in drylands. With a comparative approach we searched for plant functional types (PFTs) with a consistent response to grazing across two areas differing in climatic aridity, situated in South Africa's grassland and savanna biomes. We aggregated herbaceous species into PFTs, using hierarchical combinations of traits (from single- to three-trait PFTs). Traits relate to life history, growth form and leaf width. We first confirmed that soil and grazing gradients were largely independent from each other, and then searched in each biome for PFTs with a sensitive response to grazing, avoiding confounding with soil conditions. We found no response consistency, but biome-specific optimum aggregation levels. Three-trait PFTs (e.g. broad-leaved perennial grasses) and two-trait PFTs (e.g. perennial grasses) performed best as indicators of grazing effects in the semi-arid grassland and in the arid savanna biome, respectively. Some PFTs increased with grazing pressure in the grassland, but decreased in the savanna. We applied biome-specific grazing indicators to evaluate if differences in grazing management related to land tenure (communal versus freehold) had effects on vegetation. Tenure effects were small, which we mainly attributed to large variability in grazing pressure across farms. We conclude that the striking lack of generalizable PFT responses to grazing is due to a convergence of aridity and grazing effects, and unlikely to be overcome by more refined classification approaches. Hence, PFTs with an opposite response to grazing in the two biomes rather have a unimodal response along a gradient of additive forces of aridity and grazing. The study advocates for hierarchical trait combinations to identify localized indicator sets for grazing effects. Its methodological approach may also be useful

  14. The problems associated with the monitoring of complex workplace radiation fields at European high-energy accelerators and thermonuclear fusion facilities.

    PubMed

    Bilski, P; Blomgren, J; d'Errico, F; Esposito, A; Fehrenbacher, G; Fernàndez, F; Fuchs, A; Golnik, N; Lacoste, V; Leuschner, A; Sandri, S; Silari, M; Spurny, F; Wiegel, B; Wright, P

    2007-01-01

    The European Commission is funding within its Sixth Framework Programme a three-year project (2005-2007) called CONRAD, COordinated Network for RAdiation Dosimetry. The organisational framework for this project is provided by the European Radiation Dosimetry Group EURADOS. One task within the CONRAD project, Work Package 6 (WP6), was to provide a report outlining research needs and research activities within Europe to develop new and improved methods and techniques for the characterisation of complex radiation fields at workplaces around high-energy accelerators, but also at the next generation of thermonuclear fusion facilities. The paper provides an overview of the report, which will be available as CERN Yellow Report.

  15. Amps particle accelerator definition study

    NASA Technical Reports Server (NTRS)

    Sellen, J. M., Jr.

    1975-01-01

    The Particle Accelerator System of the AMPS (Atmospheric, Magnetospheric, and Plasmas in Space) payload is a series of charged particle accelerators to be flown with the Space Transportation System Shuttle on Spacelab missions. In the configuration presented, the total particle accelerator system consists of an energetic electron beam, an energetic ion accelerator, and both low voltage and high voltage plasma acceleration devices. The Orbiter is illustrated with such a particle accelerator system.

  16. Synthesis, spectroscopic properties, and photoconductivity of black absorbers consisting of pt(bipyridine)(dithiolate) charge transfer complexes in the presence and absence of nitrofluorenone acceptors.

    PubMed

    Browning, Charles; Hudson, Joshua M; Reinheimer, Eric W; Kuo, Fang-Ling; McDougald, Roy N; Rabaâ, Hassan; Pan, Hongjun; Bacsa, John; Wang, Xiaoping; Dunbar, Kim R; Shepherd, Nigel D; Omary, Mohammad A

    2014-11-19

    The diimine-dithiolato ambipolar complexes Pt(dbbpy)(tdt) and Pt(dmecb)(bdt) (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine; tdt(2-) = 3,4-toluenedithiolate; dmecb = 4,4'-dimethoxyester-2,2'-bipyridine; bdt(2-) = benzene-1,2-dithiolate) are prepared herein. Pt(dmecb)(bdt) exhibits photoconductivity that remains constant (photocurrent density of 1.6 mA/cm(2) from a 20 nm thin film) across the entire visible region of the solar spectrum in a Schottky diode device structure. Pt(dbbpy)(tdt) acts as donor when combined with the strong nitrofluorenone acceptors 2,7-dinitro-9-fluorenone (DNF), 2,4,7-trinitro-9-fluorenone (TRNF), or 2,4,5,7-tetranitro-9-fluorenone (TENF). Supramolecular charge transfer stacks form and exhibit various donor-acceptor stacking patterns. The crystalline solids are "black absorbers" that exhibit continuous absorptions spanning the entire visible region and significant ultraviolet and near-infrared wavelengths, the latter including long wavelengths that the donor or acceptor molecules alone do not absorb. Absorption spectra reveal the persistence of donor-acceptor interactions in solution, as characterized by low-energy donor/acceptor charge transfer (DACT) bands. Crystal structures show closely packed stacks with distances that underscore intermolecular DACT. (1)H NMR provides further evidence of DACT, as manifested by upfield shifts of aromatic protons in the binary adducts versus their free components, whereas 2D nuclear Overhauser effect spectroscopy (NOESY) spectra suggest coupling between dithiolate donor protons with nitrofluorenone acceptor protons, in correlation with the solid-state stacking. The NMR spectra also show significant peak broadening, indicating some paramagnetism verified by magnetic susceptibility data. Solid-state absorption spectra reveal further red shifts and increased relative intensities of DACT bands for the solid adducts vs solution, suggesting cooperativity of the DACT phenomenon in the solid state, as further

  17. 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.

  18. Complexation of the vulcanization accelerator tetramethylthiuram disulfide and related molecules with zinc compounds including zinc oxide clusters (Zn4O4).

    PubMed

    Steudel, Ralf; Steudel, Yana; Wong, Ming Wah

    2008-01-01

    Zinc chemicals are used as activators in the vulcanization of organic polymers with sulfur to produce elastic rubbers. In this work, the reactions of Zn(2+), ZnMe(2), Zn(OMe)(2), Zn(OOCMe)(2), and the heterocubane cluster Zn(4)O(4) with the vulcanization accelerator tetramethylthiuram disulfide (TMTD) and with the related radicals and anions Me(2)NCS(2)(*), Me(2)NCS(3)(*), Me(2)NCS(2)(-), and Me(2)NCS(3)(-) have been studied by quantum chemical methods at the MP2/6-31+G(2df,p)//B3LYP/6-31+G* level of theory. More than 35 zinc complexes have been structurally characterized and the energies of formation from their components calculated for the first time. The binding energy of TMTD as a bidendate ligand increases in the order ZnMe(2)complexes with the radicals Me(2)NCS(2)(*) and Me(2)NCS(3)(*). Dissociation of the TMTD molecule at the S-S bond on reaction with the Zn(4)O(4) cluster is predicted to be strongly exothermic, in sharp contrast to the endothermic S-S bond dissociation of the free molecule. The same holds for tetramethylthiuram trisulfide (TMTT). Surprisingly, the resulting complexes contain Zn-S as well as S-O bonds. The Zn(4)O(4) nanocluster serves here as a model for bulk zinc oxide used as an activator in rubber vulcanization by sulfur. The further uptake of sulfur atoms by the various complexes from S(8) or TMTD with formation of species derived from the radical Me(2)NCS(3)(*) or the trithiocarbamate anion Me(2)NCS(3)(-) is endothermic for mono- and dinuclear zinc dithiocarbamate (dtc) complexes such as [Zn(dtc)(2)] and [Zn(2)(dtc)(4)], but exothermic in the case of polynuclear zinc oxide species containing bridging ligands as in [Zn(4)O(4)(mu-S(2)CNMe(2))] and [Zn(4)O(4)(mu-dtc)]. Therefore, zinc oxide as a polynuclear species is predicted to promote the formation of trisulfido complexes, which are generally assumed to serve as catalysts for the transfer of

  19. Complexation of the vulcanization accelerator tetramethylthiuram disulfide and related molecules with zinc compounds including zinc oxide clusters (Zn4O4).

    PubMed

    Steudel, Ralf; Steudel, Yana; Wong, Ming Wah

    2008-01-01

    Zinc chemicals are used as activators in the vulcanization of organic polymers with sulfur to produce elastic rubbers. In this work, the reactions of Zn(2+), ZnMe(2), Zn(OMe)(2), Zn(OOCMe)(2), and the heterocubane cluster Zn(4)O(4) with the vulcanization accelerator tetramethylthiuram disulfide (TMTD) and with the related radicals and anions Me(2)NCS(2)(*), Me(2)NCS(3)(*), Me(2)NCS(2)(-), and Me(2)NCS(3)(-) have been studied by quantum chemical methods at the MP2/6-31+G(2df,p)//B3LYP/6-31+G* level of theory. More than 35 zinc complexes have been structurally characterized and the energies of formation from their components calculated for the first time. The binding energy of TMTD as a bidendate ligand increases in the order ZnMe(2)complexes with the radicals Me(2)NCS(2)(*) and Me(2)NCS(3)(*). Dissociation of the TMTD molecule at the S-S bond on reaction with the Zn(4)O(4) cluster is predicted to be strongly exothermic, in sharp contrast to the endothermic S-S bond dissociation of the free molecule. The same holds for tetramethylthiuram trisulfide (TMTT). Surprisingly, the resulting complexes contain Zn-S as well as S-O bonds. The Zn(4)O(4) nanocluster serves here as a model for bulk zinc oxide used as an activator in rubber vulcanization by sulfur. The further uptake of sulfur atoms by the various complexes from S(8) or TMTD with formation of species derived from the radical Me(2)NCS(3)(*) or the trithiocarbamate anion Me(2)NCS(3)(-) is endothermic for mono- and dinuclear zinc dithiocarbamate (dtc) complexes such as [Zn(dtc)(2)] and [Zn(2)(dtc)(4)], but exothermic in the case of polynuclear zinc oxide species containing bridging ligands as in [Zn(4)O(4)(mu-S(2)CNMe(2))] and [Zn(4)O(4)(mu-dtc)]. Therefore, zinc oxide as a polynuclear species is predicted to promote the formation of trisulfido complexes, which are generally assumed to serve as catalysts for the transfer of

  20. 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.

  1. 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.

  2. Radiation Safety Systems for Accelerator Facilities

    SciTech Connect

    James C. Liu; Jeffrey S. Bull; John Drozdoff; Robert May; Vaclav Vylet

    2001-10-01

    The Radiation Safety System (RSS) of an accelerator facility is used to protect people from prompt radiation hazards associated with accelerator operation. The RSS is a fully interlocked, engineered system with a combination of passive and active elements that are reliable, redundant, and fail-safe. The RSS consists of the Access Control System (ACS) and the Radiation Containment System (RCS). The ACS is to keep people away from the dangerous radiation inside the shielding enclosure. The RCS limits and contains the beam/radiation conditions to protect people from the prompt radiation hazards outside the shielding enclosure in both normal and abnormal operations. The complexity of a RSS depends on the accelerator and its operation, as well as associated hazard conditions. The approaches of RSS among different facilities can be different. This report gives a review of the RSS for accelerator facilities.

  3. High binding yet accelerated guest rotation within a cucurbit[7]uril complex. Toward paramagnetic gyroscopes and rolling nanomachines.

    PubMed

    Casano, G; Poulhès, F; Tran, T K; Ayhan, M M; Karoui, H; Siri, D; Gaudel-Siri, A; Rockenbauer, A; Jeschke, G; Bardelang, D; Tordo, P; Ouari, O

    2015-07-28

    The (15-oxo-3,7,11-triazadispiro[5.1.5.3]hexadec-7-yl)oxidanyl, a bis-spiropiperidinium nitroxide derived from TEMPONE, can be included in cucurbit[7]uril to form a strong (K(a)∼ 2 × 10(5) M(-1)) CB[7]@bPTO complex. EPR and MS spectra, DFT calculations, and unparalleled increased resistance (a factor of ∼10(3)) toward ascorbic acid reduction show evidence of deep inclusion of bPTO inside CB[7]. The unusual shape of the CB[7]@bPTO EPR spectrum can be explained by an anisotropic Brownian rotational diffusion, the global tumbling of the complex being slower than rotation of bPTO around its "long molecular axis" inside CB[7]. The CB[7] (stator) with the encapsulated bPTO (rotator) behaves as a supramolecular paramagnetic rotor with increased rotational speed of the rotator that has great potential for advanced nanoscale machines requiring wheels such as cucurbiturils with virtually no friction between the wheel and the axle for optimum wheel rotation (i.e. nanopulleys and nanocars).

  4. Silencing SlELP2L, a tomato Elongator complex protein 2-like gene, inhibits leaf growth, accelerates leaf, sepal senescence, and produces dark-green fruit.

    PubMed

    Zhu, Mingku; Li, Yali; Chen, Guoping; Ren, Lijun; Xie, Qiaoli; Zhao, Zhiping; Hu, Zongli

    2015-01-09

    The multi-subunit complex Elongator interacts with elongating RNA polymerase II (RNAPII) and is thought to facilitate transcription through histone acetylation. Elongator is highly conserved in eukaryotes, yet has multiple kingdom-specific functions in diverse organisms. Recent genetic studies performed in Arabidopsis have demonstrated that Elongator functions in plant growth and development, and in response to biotic and abiotic stress. However, little is known about its roles in other plant species. Here, we study the function of an Elongator complex protein 2-like gene in tomato, here designated as SlELP2L, through RNAi-mediated gene silencing. Silencing SlELP2L in tomato inhibits leaf growth, accelerates leaf and sepal senescence, and produces dark-green fruit with reduced GA and IAA contents in leaves, and increased chlorophyll accumulation in pericarps. Gene expression analysis indicated that SlELP2L-silenced plants had reduced transcript levels of ethylene- and ripening-related genes during fruit ripening with slightly decreased carotenoid content in fruits, while the expression of DNA methyltransferase genes was up-regulated, indicating that SlELP2L may modulate DNA methylation in tomato. Besides, silencing SlELP2L increases ABA sensitivity in inhibiting seedling growth. These results suggest that SlELP2L plays important roles in regulating plant growth and development, as well as in response to ABA in tomato.

  5. Phosphorylation of CDC25A on SER283 in late S/G2 by CDK/cyclin complexes accelerates mitotic entry.

    PubMed

    Mazzolini, Laurent; Broban, Anaïs; Froment, Carine; Burlet-Schiltz, Odile; Besson, Arnaud; Manenti, Stéphane; Dozier, Christine

    2016-10-17

    The Cdc25A phosphatase is an essential activator of CDK-cyclin complexes at all steps of the eukaryotic cell cycle. The activity of Cdc25A is itself regulated in part by positive and negative feedback regulatory loops performed by its CDK-cyclin substrates that occur in G1 as well as during the G1/S and G2/M transitions. However, the regulation of Cdc25A during G2 phase progression before mitotic entry has not been intensively characterized. Here, we identify by mass spectrometry analysis a new phosphorylation event of Cdc25A on Serine283. Phospho-specific antibodies revealed that the phosphorylation of this residue appears in late S/G2 phase of an unperturbed cell cycle and is performed by CDK-cyclin complexes. Overexpression studies of wild-type and non-phosphorylatable mutant forms of Cdc25A indicated that Ser283 phosphorylation increases the G2/M-promoting activity of the phosphatase without impacting its stability or subcellular localization. Our results therefore identify a new positive regulatory loop between Cdc25A and its CDK-cyclin substrates which contributes to accelerate entry into mitosis through the regulation of Cdc25A activity in G2. PMID:27580187

  6. 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.

  7. 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.

  8. Radiation from Accelerated Particles in Shocks and Reconnections

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Choi, E. J.; Min, K. W.; Niemiec, J.; Fishman, G. J.; Zhang, B.; Hardee, P.; Mizuno, Y.; Medvedev, M.; Nordlund, A.; Frederiksen, J. T.; Sol, H.; Pohl, M.; Hartmann, D. H.

    2012-01-01

    We have investigated particle acceleration and shock structure associated with an unmagnetized relativistic jets propagating into an unmagnetized plasmas. Strong magnetic fields generated in the trailing shock contribute to the electrons transverse deflection and acceleration. We have calculated, self-consistently, the radiation from electrons accelerated in the turbulent magnetic fields. We found that the synthetic spectra depend on the Lorentz factor of the jet, its thermal temperature and strength of the generated magnetic fields. The properties of the radiation may be important for understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets in general, and supernova remnants

  9. Combined generating-accelerating buncher for compact linear accelerators

    NASA Astrophysics Data System (ADS)

    Savin, E. A.; Matsievskiy, S. V.; Sobenin, N. P.; Sokolov, I. D.; Zavadtsev, A. A.

    2016-09-01

    Described in the previous article [1] method of the power extraction from the modulated electron beam has been applied to the compact standing wave electron linear accelerator feeding system, which doesnt require any connection waveguides between the power source and the accelerator itself [2]. Generating and accelerating bunches meet in the hybrid accelerating cell operating at TM020 mode, thus the accelerating module is placed on the axis of the generating module, which consists from the pulsed high voltage electron sources and electrons dumps. This combination makes the accelerator very compact in size which is very valuable for the modern applications such as portable inspection sources. Simulations and geometry cold tests are presented.

  10. Accelerated life testing effects on CMOS microcircuit characteristics

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Accelerated life tests were performed on CMOS microcircuits to predict their long term reliability. The consistency of the CMOS microcircuit activation energy between the range of 125 C to 200 C and the range 200 C to 250 C was determined. Results indicate CMOS complexity and the amount of moisture detected inside the devices after testing influences time to failure of tested CMOS devices.

  11. A code for analysis of the fine structure in near-rigid weakly-bonded open-shell complexes that consist of a diatomic radical in a Σ3 state and a closed-shell molecule

    NASA Astrophysics Data System (ADS)

    Fawzy, Wafaa M.

    2010-10-01

    A FORTRAN code is developed for simulation and fitting the fine structure of a planar weakly-bonded open-shell complex that consists of a diatomic radical in a Σ3 electronic state and a diatomic or a polyatomic closed-shell molecule. The program sets up the proper total Hamiltonian matrix for a given J value and takes account of electron-spin-electron-spin, electron-spin rotation interactions, and the quartic and sextic centrifugal distortion terms within the complex. Also, R-dependence of electron-spin-electron-spin and electron-spin rotation couplings are considered. The code does not take account of effects of large-amplitude internal rotation of the diatomic radical within the complex. It is assumed that the complex has a well defined equilibrium geometry so that effects of large amplitude motion are negligible. Therefore, the computer code is suitable for a near-rigid rotor. Numerical diagonalization of the matrix provides the eigenvalues and the eigenfunctions that are necessary for calculating energy levels, frequencies, relative intensities of infrared or microwave transitions, and expectation values of the quantum numbers within the complex. Goodness of all the quantum numbers, with exception of J and parity, depends on relative sizes of the product of the rotational constants and quantum numbers (i.e. BJ, CJ, and AK), electron-spin-electron-spin, and electron-spin rotation couplings, as well as the geometry of the complex. Therefore, expectation values of the quantum numbers are calculated in the eigenfunctions basis of the complex. The computational time for the least squares fits has been significantly reduced by using the Hellman-Feynman theory for calculating the derivatives. The computer code is useful for analysis of high resolution infrared and microwave spectra of a planar near-rigid weakly-bonded open-shell complex that contains a diatomic fragment in a Σ3 electronic state and a closed-shell molecule. The computer program was successfully

  12. Dinitrosyl iron complexes with glutathione incorporated into a collagen matrix as a base for the design of drugs accelerating skin wound healing.

    PubMed

    Shekhter, Anatoly B; Rudenko, Tatyana G; Istranov, Leonid P; Guller, Anna E; Borodulin, Rostislav R; Vanin, Anatoly F

    2015-10-12

    Composites of a collagen matrix and dinitrosyl iron complexes with glutathione (DNIC-GS) (in a dose of 4.0 μmoles per item) in the form of spongy sheets (DNIC-Col) were prepared and then topically applied in rat excisional full-thickness skin wound model. The effects of DNIC-Col were studied in comparison with spontaneously healing wounds (SpWH) and wounds treated with collagen sponges (Col) without DNIC-GS. The composites induced statistically and clinically significant acceleration of complete wound closure (21±1 day versus 23±1 day and 26±1 day for DNIC-Col, Col and SpWH, respectively). Histological examination of wound tissues on days 4, 14, 18 and 21 after surgery demonstrated that this improvement was supported by enhanced growth, maturation and fibrous transformation of granulation tissue and earlier epithelization of the injured area in rats treated with DNIC-Col composites benchmarked against Col and SpWH. It is suggested that the positive effect of the new pharmaceutical material on wound healing is based on the release of NO from decomposing DNIC. This effect is believed to be potentiated by the synergy of DNIC and collagen.

  13. 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.

  14. Consistent model driven architecture

    NASA Astrophysics Data System (ADS)

    Niepostyn, Stanisław J.

    2015-09-01

    The goal of the MDA is to produce software systems from abstract models in a way where human interaction is restricted to a minimum. These abstract models are based on the UML language. However, the semantics of UML models is defined in a natural language. Subsequently the verification of consistency of these diagrams is needed in order to identify errors in requirements at the early stage of the development process. The verification of consistency is difficult due to a semi-formal nature of UML diagrams. We propose automatic verification of consistency of the series of UML diagrams originating from abstract models implemented with our consistency rules. This Consistent Model Driven Architecture approach enables us to generate automatically complete workflow applications from consistent and complete models developed from abstract models (e.g. Business Context Diagram). Therefore, our method can be used to check practicability (feasibility) of software architecture models.

  15. Presentation on a Space Acceleration Measurement System (SAMS)

    NASA Technical Reports Server (NTRS)

    Chase, Theodore L.

    1990-01-01

    The primary objective of the Space Acceleration Measurement Systems (SAMS) project is to provide an acceleration measurement system capable of serving a wide variety of space experiments. The design of the system being developed under this project takes into consideration requirements for experiments located in the middeck, in the orbiter bay, and in Spacelab. In addition to measuring, conditioning, and recording accelerations, the system will be capable of performing complex calculations and interactive control. The main components consist of a remote triaxial optical storage device. In operation, the triaxial sensor head produces output signals in response to acceleration inputs. These signals are preamplified, filtered and converted into digital data which is then transferred to optical memory. The system design is modular, facilitating both software and hardware upgrading as technology advances. Two complete acceleration measurement flight systems will be build and tested under this project.

  16. Indexing Consistency and Quality.

    ERIC Educational Resources Information Center

    Zunde, Pranas; Dexter, Margaret E.

    Proposed is a measure of indexing consistency based on the concept of "fuzzy sets." By this procedure a higher consistency value is assigned if indexers agree on the more important terms than if they agree on less important terms. Measures of the quality of an indexer's work and exhaustivity of indexing are also proposed. Experimental data on…

  17. Indexing Consistency and Quality.

    ERIC Educational Resources Information Center

    Zunde, Pranas; Dexter, Margaret E.

    A measure of indexing consistency is developed based on the concept of 'fuzzy sets'. It assigns a higher consistency value if indexers agree on the more important terms than if they agree on less important terms. Measures of the quality of an indexer's work and exhaustivity of indexing are also proposed. Experimental data on indexing consistency…

  18. Consistency relation in cosmology

    SciTech Connect

    Chiba, Takeshi; Takahashi, Ryuichi

    2007-05-15

    We provide a consistency relation between cosmological observables in general relativity without relying on the equation of state of dark energy. The consistency relation should be satisfied if general relativity is the correct theory of gravity and dark energy clustering is negligible. As an extension, we also provide the DGP counterpart of the relation.

  19. Centrifuge Study of Pilot Tolerance to Acceleration and the Effects of Acceleration on Pilot Performance

    NASA Technical Reports Server (NTRS)

    Creer, Brent Y.; Smedal, Harald A.; Wingrove, Rodney C.

    1960-01-01

    A research program the general objective of which was to measure the effects of various sustained accelerations on the control performance of pilots, was carried out on the Aviation Medical Acceleration Laboratory centrifuge, U.S. Naval Air Development Center, Johnsville, PA. The experimental setup consisted of a flight simulator with the centrifuge in the control loop. The pilot performed his control tasks while being subjected to acceleration fields such as might be encountered by a forward-facing pilot flying an atmosphere entry vehicle. The study was divided into three phases. In one phase of the program, the pilots were subjected to a variety of sustained linear acceleration forces while controlling vehicles with several different sets of longitudinal dynamics. Here, a randomly moving target was displayed to the pilot on a cathode-ray tube. For each combination of acceleration field and vehicle dynamics, pilot tracking accuracy was measured and pilot opinion of the stability and control characteristics was recorded. Thus, information was obtained on the combined effects of complexity of control task and magnitude and direction of acceleration forces on pilot performance. These tests showed that the pilot's tracking performance deteriorated markedly at accelerations greater than about 4g when controlling a lightly damped vehicle. The tentative conclusion was also reached that regardless of the airframe dynamics involved, the pilot feels that in order to have the same level of control over the vehicle, an increase in the vehicle dynamic stability was required with increases in the magnitudes of the acceleration impressed upon the pilot. In another phase, boundaries of human tolerance of acceleration were established for acceleration fields such as might be encountered by a pilot flying an orbital vehicle. A special pilot restraint system was developed to increase human tolerance to longitudinal decelerations. The results of the tests showed that human tolerance

  20. Complex polarization propagator approach in the restricted open-shell, self-consistent field approximation: the near K-edge X-ray absorption fine structure spectra of allyl and copper phthalocyanine.

    PubMed

    Linares, Mathieu; Stafström, Sven; Rinkevicius, Zilvinas; Ågren, Hans; Norman, Patrick

    2011-05-12

    A presentation of the complex polarization propagator in the restricted open-shell self-consistent field approximation is given. It rests on a formulation of a resonant-convergent, first-order polarization propagator approach that makes it possible to directly calculate the X-ray absorption cross section at a particular frequency without explicitly addressing the excited states. The quality of the predicted X-ray spectra relates only to the type of density functional applied without any separate treatment of dynamical relaxation effects. The method is applied to the calculation of the near K-edge X-ray absorption fine structure spectra of allyl and copper phthalocyanine. Comparison is made between the spectra of the radicals and those of the corresponding cations and anions to assess the effect of the increase of electron charge in the frontier orbital. The method offers the possibility for unique assignment of symmetry-independent atoms. The overall excellent spectral agreement motivates the application of the method as a routine precise tool for analyzing X-ray absorption of large systems of technological interest.

  1. Guidelines for Developing an Academic Acceleration Policy

    ERIC Educational Resources Information Center

    Colangelo, Nicholas; Assouline, Susan G.; Marron, Maureen A.; Castellano, Jaime A.; Clinkenbeard, Pamela R.; Rogers, Karen; Calvert, Eric; Malek, Rosanne; Smith, Donnajo

    2010-01-01

    As an educational intervention, acceleration is decidedly effective for high-ability students. The research support for acceleration that has accumulated over many decades is robust and consistent and allows us to confidently state that carefully planned acceleration decisions are successful. Both grade-based and content-based acceleration are…

  2. A polysaccharide-peptide complex from abalone mushroom (Pleurotus abalonus) fruiting bodies increases activities and gene expression of antioxidant enzymes and reduces lipid peroxidation in senescence-accelerated mice.

    PubMed

    Li, L; Ng, T B; Song, M; Yuan, F; Liu, Z K; Wang, C L; Jiang, Y; Fu, M; Liu, F

    2007-06-01

    The antioxidant effects of a polysaccharide-peptide complex (F22) from mushroom (Pleurotus abalonus)-fruiting bodies were studied. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in the liver, kidney, and brain of senescence-accelerated mice showed a marked increase after treatment with the polysaccharide-peptide complex. Concurrently, the gene expression levels of SOD, CAT, and GPx, as determined with real-time polymerase chain reaction, were up-regulated in the liver, kidney, and brain, whereas the MDA content in these organs declined. The maximal lifespan of the mice was prolonged.

  3. Dielectric assist accelerating structure

    NASA Astrophysics Data System (ADS)

    Satoh, D.; Yoshida, M.; Hayashizaki, N.

    2016-01-01

    A higher-order TM02 n mode accelerating structure is proposed based on a novel concept of dielectric loaded rf cavities. This accelerating structure consists of ultralow-loss dielectric cylinders and disks with irises which are periodically arranged in a metallic enclosure. Unlike conventional dielectric loaded accelerating structures, most of the rf power is stored in the vacuum space near the beam axis, leading to a significant reduction of the wall loss, much lower than that of conventional normal-conducting linac structures. This allows us to realize an extremely high quality factor and a very high shunt impedance at room temperature. A simulation of a 5 cell prototype design with an existing alumina ceramic indicates an unloaded quality factor of the accelerating mode over 120 000 and a shunt impedance exceeding 650 M Ω /m at room temperature.

  4. HEAVY ION LINEAR ACCELERATOR

    DOEpatents

    Van Atta, C.M.; Beringer, R.; Smith, L.

    1959-01-01

    A linear accelerator of heavy ions is described. The basic contributions of the invention consist of a method and apparatus for obtaining high energy particles of an element with an increased charge-to-mass ratio. The method comprises the steps of ionizing the atoms of an element, accelerating the resultant ions to an energy substantially equal to one Mev per nucleon, stripping orbital electrons from the accelerated ions by passing the ions through a curtain of elemental vapor disposed transversely of the path of the ions to provide a second charge-to-mass ratio, and finally accelerating the resultant stripped ions to a final energy of at least ten Mev per nucleon.

  5. Infanticide and moral consistency.

    PubMed

    McMahan, Jeff

    2013-05-01

    The aim of this essay is to show that there are no easy options for those who are disturbed by the suggestion that infanticide may on occasion be morally permissible. The belief that infanticide is always wrong is doubtfully compatible with a range of widely shared moral beliefs that underlie various commonly accepted practices. Any set of beliefs about the morality of abortion, infanticide and the killing of animals that is internally consistent and even minimally credible will therefore unavoidably contain some beliefs that are counterintuitive.

  6. Consistent Quantum Theory

    NASA Astrophysics Data System (ADS)

    Griffiths, Robert B.

    2001-11-01

    Quantum mechanics is one of the most fundamental yet difficult subjects in physics. Nonrelativistic quantum theory is presented here in a clear and systematic fashion, integrating Born's probabilistic interpretation with Schrödinger dynamics. Basic quantum principles are illustrated with simple examples requiring no mathematics beyond linear algebra and elementary probability theory. The quantum measurement process is consistently analyzed using fundamental quantum principles without referring to measurement. These same principles are used to resolve several of the paradoxes that have long perplexed physicists, including the double slit and Schrödinger's cat. The consistent histories formalism used here was first introduced by the author, and extended by M. Gell-Mann, J. Hartle and R. Omnès. Essential for researchers yet accessible to advanced undergraduate students in physics, chemistry, mathematics, and computer science, this book is supplementary to standard textbooks. It will also be of interest to physicists and philosophers working on the foundations of quantum mechanics. Comprehensive account Written by one of the main figures in the field Paperback edition of successful work on philosophy of quantum mechanics

  7. Wakefield accelerators

    SciTech Connect

    Simpson, J.D.

    1990-01-01

    The search for new methods to accelerate particle beams to high energy using high gradients has resulted in a number of candidate schemes. One of these, wakefield acceleration, has been the subject of considerable R D in recent years. This effort has resulted in successful proof of principle experiments and in increased understanding of many of the practical aspects of the technique. Some wakefield basics plus the status of existing and proposed experimental work is discussed, along with speculations on the future of wake field acceleration. 10 refs., 6 figs.

  8. COMMISSIONING OF THE SPALLATION NEUTRON SOURCE ACCELERATOR SYSTEMS

    SciTech Connect

    Plum, Michael A

    2007-01-01

    The Spallation Neutron Source accelerator complex consists of a 2.5 MeV H- front-end injector system, a 186 MeV normal-conducting linear accelerator, a 1 GeV superconducting linear accelerator, an accumulator ring, and associated beam transport lines. The linac was commissioned in five discrete runs, starting in 2002 and completed in 2005. The accumulator ring and associated beam transport lines were commissioned in two runs from January to April 2006. With the completed commissioning of the SNS accelerator, the facility has begun initial low-power operations. In the course of beam commissioning, most beam performance parameters and beam intensity goals have been achieved at low duty factor. A number of beam dynamics measurements have been performed, including emittance evolution, transverse coupling in the ring, beam instability thresholds, and beam distributions on the target. The commissioning results, achieved beam performance and initial operating experience of the SNS will be discussed

  9. Beam emittance control by changing injection painting area in a pulse-to-pulse mode in the 3-GeV rapid cycling synchrotron of Japan Proton Accelerator Research Complex

    NASA Astrophysics Data System (ADS)

    Saha, P. K.; Harada, H.; Hayashi, N.; Horino, K.; Hotchi, H.; Kinsho, M.; Takayanagi, T.; Tani, N.; Togashi, T.; Ueno, T.; Yamazaki, Y.; Irie, Y.

    2013-12-01

    The 3-GeV rapid cycling synchrotron (RCS) of Japan Proton Accelerator Research Complex (J-PARC) simultaneously delivers high intensity beam to the Material and Life Science Experimental Facility (MLF) as well as to the main ring (MR) at a repetition rate of 25 Hz. The RCS is designed for a beam power of 1 MW. RCS has to meet not only the need of power upgrade but also the specific requirement of each downstream facility. One of the issues, especially for high intensity operation, is to maintain two different transverse sizes of the extracted beam for MLF and MR; namely, a wider beam for MLF in order to reduce damage on the neutron production target but reversely a narrower one for the MR in order to ensure a permissible beam loss in the beam transport line of 3-GeV to MR and also in the MR. We proposed pulse-to-pulse direct control of the transverse painting area during the RCS beam injection process in order to get an extracted beam profile as desired. In addition to two existing dc septum magnets used for fixing injected beam trajectory for MLF beam, two additional dipoles named pulse steering magnets are designed for that purpose in order to control injected beam trajectory for a smaller painting area for the MR. The magnets are already installed in the injection beam transport line and successfully commissioned well in advance before they will be put in normal operation in 2014 for the 400 MeV injected beam energy upgraded from that of the present 181 MeV. Their parameters are found to be consistent to those expected in the corresponding numerical simulations. A trial one cycle user operation run for a painting area of 100πmmmrad for the MR switching from the MLF painting area of 150πmmmrad has also been successfully carried out. The extracted beam profile for the MR is measured to be sufficiently narrower as compared to that for the MLF, consistent with numerical simulation successfully demonstrating validity of the present principle.

  10. Consistent quantum measurements

    NASA Astrophysics Data System (ADS)

    Griffiths, Robert B.

    2015-11-01

    In response to recent criticisms by Okon and Sudarsky, various aspects of the consistent histories (CH) resolution of the quantum measurement problem(s) are discussed using a simple Stern-Gerlach device, and compared with the alternative approaches to the measurement problem provided by spontaneous localization (GRW), Bohmian mechanics, many worlds, and standard (textbook) quantum mechanics. Among these CH is unique in solving the second measurement problem: inferring from the measurement outcome a property of the measured system at a time before the measurement took place, as is done routinely by experimental physicists. The main respect in which CH differs from other quantum interpretations is in allowing multiple stochastic descriptions of a given measurement situation, from which one (or more) can be selected on the basis of its utility. This requires abandoning a principle (termed unicity), central to classical physics, that at any instant of time there is only a single correct description of the world.

  11. ION ACCELERATOR

    DOEpatents

    Bell, J.S.

    1959-09-15

    An arrangement for the drift tubes in a linear accelerator is described whereby each drift tube acts to shield the particles from the influence of the accelerating field and focuses the particles passing through the tube. In one embodiment the drift tube is splii longitudinally into quadrants supported along the axis of the accelerator by webs from a yoke, the quadrants. webs, and yoke being of magnetic material. A magnetic focusing action is produced by energizing a winding on each web to set up a magnetic field between adjacent quadrants. In the other embodiment the quadrants are electrically insulated from each other and have opposite polarity voltages on adjacent quadrants to provide an electric focusing fleld for the particles, with the quadrants spaced sufficienily close enough to shield the particles within the tube from the accelerating electric field.

  12. Acceleration switch

    DOEpatents

    Abbin, J.P. Jr.; Devaney, H.F.; Hake, L.W.

    1979-08-29

    The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

  13. Acceleration switch

    DOEpatents

    Abbin, Jr., Joseph P.; Devaney, Howard F.; Hake, Lewis W.

    1982-08-17

    The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

  14. LINEAR ACCELERATOR

    DOEpatents

    Christofilos, N.C.; Polk, I.J.

    1959-02-17

    Improvements in linear particle accelerators are described. A drift tube system for a linear ion accelerator reduces gap capacity between adjacent drift tube ends. This is accomplished by reducing the ratio of the diameter of the drift tube to the diameter of the resonant cavity. Concentration of magnetic field intensity at the longitudinal midpoint of the external sunface of each drift tube is reduced by increasing the external drift tube diameter at the longitudinal center region.

  15. Assessment of self-consistent field convergence in spin-dependent relativistic calculations

    NASA Astrophysics Data System (ADS)

    Nakano, Masahiko; Seino, Junji; Nakai, Hiromi

    2016-07-01

    This Letter assesses the self-consistent field (SCF) convergence behavior in the generalized Hartree-Fock (GHF) method. Four acceleration algorithms were implemented for efficient SCF convergence in the GHF method: the damping algorithm, the conventional direct inversion in the iterative subspace (DIIS), the energy-DIIS (EDIIS), and a combination of DIIS and EDIIS. Four different systems with varying complexity were used to investigate the SCF convergence using these algorithms, ranging from atomic systems to metal complexes. The numerical assessments demonstrated the effectiveness of a combination of DIIS and EDIIS for GHF calculations in comparison with the other discussed algorithms.

  16. The Brookhaven Accelerator Test Facility

    SciTech Connect

    Batchelor, K.; Ben-Zvi, I.; Fernow, R.C.; Fischer, J.; Fisher, A.S.; Gallardo, J.; Jialin, Xie; Kirk, H.G.; Parsa, Z.; Palmer, R.B.; Rao, T.; Rogers, J.; Sheehan, J.; Tsang, T.Y.F.; Ulc, S.; Van Steenbergen, A.; Woodle, M.; Zhang, R.S. ); McDonald, K.T.; Russell, D.P. ); Jiang, Z.Y. (State Univ. of New York, Stony Brook, NY (Un

    1990-01-01

    The Accelerator Test Facility (ATF), presently under construction at Brookhaven National laboratory, is described. It consists of a 50-MeV electron beam synchronizable to a high-peak power CO{sub 2} laser. The interaction of electrons with the laser field will be probed, with some emphasis on exploring laser-based acceleration techniques. 5 refs., 2 figs.

  17. Muon Acceleration - RLA and FFAG

    SciTech Connect

    Bogacz, Alex

    2011-10-01

    Various acceleration schemes for muons are presented. The overall goal of the acceleration systems: large acceptance acceleration to 25 GeV and 'beam shaping' can be accomplished by various fixed field accelerators at different stages. They involve three superconducting linacs: a single pass linear Pre-accelerator followed by a pair of multi-pass Recirculating Linear Accelerators (RLA) and finally a non-scaling FFAG ring. The present baseline acceleration scenario has been optimized to take maximum advantage of appropriate acceleration scheme at a given stage. The solenoid based Pre-accelerator offers very large acceptance and facilitates correction of energy gain across the bunch and significant longitudinal compression trough induced synchrotron motion. However, far off-crest acceleration reduces the effective acceleration gradient and adds complexity through the requirement of individual RF phase control for each cavity. The RLAs offer very efficient usage of high gradient superconducting RF and ability to adjust path-length after each linac pass through individual return arcs with uniformly periodic FODO optics suitable for chromatic compensation of emittance dilution with sextupoles. However, they require spreaders/recombiners switchyards at both linac ends and significant total length of the arcs. The non-scaling Fixed Field Alternating Gradient (FFAG) ring combines compactness with very large chromatic acceptance (twice the injection energy) and it allows for large number of passes through the RF (at least eight, possibly as high as 15).

  18. Microwave inverse Cerenkov accelerator

    NASA Astrophysics Data System (ADS)

    Zhang, T. B.; Marshall, T. C.; LaPointe, M. A.; Hirshfield, J. L.

    1997-03-01

    A Microwave Inverse Cerenkov Accelerator (MICA) is currently under construction at the Yale Beam Physics Laboratory. The accelerating structure in MICA consists of an axisymmetric dielectrically lined waveguide. For the injection of 6 MeV microbunches from a 2.856 GHz RF gun, and subsequent acceleration by the TM01 fields, particle simulation studies predict that an acceleration gradient of 6.3 MV/m can be achieved with a traveling-wave power of 15 MW applied to the structure. Synchronous injection into a narrow phase window is shown to allow trapping of all injected particles. The RF fields of the accelerating structure are shown to provide radial focusing, so that longitudinal and transverse emittance growth during acceleration is small, and that no external magnetic fields are required for focusing. For 0.16 nC, 5 psec microbunches, the normalized emittance of the accelerated beam is predicted to be less than 5πmm-mrad. Experiments on sample alumina tubes have been conducted that verify the theoretical dispersion relation for the TM01 mode over a two-to-one range in frequency. No excitation of axisymmetric or non-axisymmetric competing waveguide modes was observed. High power tests showed that tangential electric fields at the inner surface of an uncoated sample of alumina pipe could be sustained up to at least 8.4 MV/m without breakdown. These considerations suggest that a MICA test accelerator can be built to examine these predictions using an available RF power source, 6 MeV RF gun and associated beam line.

  19. Accelerated molecular dynamics methods

    SciTech Connect

    Perez, Danny

    2011-01-04

    The molecular dynamics method, although extremely powerful for materials simulations, is limited to times scales of roughly one microsecond or less. On longer time scales, dynamical evolution typically consists of infrequent events, which are usually activated processes. This course is focused on understanding infrequent-event dynamics, on methods for characterizing infrequent-event mechanisms and rate constants, and on methods for simulating long time scales in infrequent-event systems, emphasizing the recently developed accelerated molecular dynamics methods (hyperdynamics, parallel replica dynamics, and temperature accelerated dynamics). Some familiarity with basic statistical mechanics and molecular dynamics methods will be assumed.

  20. Physics design of an accelerator for an accelerator-driven subcritical system

    NASA Astrophysics Data System (ADS)

    Li, Zhihui; Cheng, Peng; Geng, Huiping; Guo, Zhen; He, Yuan; Meng, Cai; Ouyang, Huafu; Pei, Shilun; Sun, Biao; Sun, Jilei; Tang, Jingyu; Yan, Fang; Yang, Yao; Zhang, Chuang; Yang, Zheng

    2013-08-01

    An accelerator-driven subcritical system (ADS) program was launched in China in 2011, which aims to design and build an ADS demonstration facility with the capability of more than 1000 MW thermal power in multiple phases lasting about 20 years. The driver linac is defined to be 1.5 GeV in energy, 10 mA in current and in cw operation mode. To meet the extremely high reliability and availability, the linac is designed with much installed margin and fault tolerance, including hot-spare injectors and local compensation method for key element failures. The accelerator complex consists of two parallel 10-MeV injectors, a joint medium-energy beam transport line, a main linac, and a high-energy beam transport line. The superconducting acceleration structures are employed except for the radio frequency quadrupole accelerators (RFQs) which are at room temperature. The general design considerations and the beam dynamics design of the driver linac complex are presented here.

  1. Beamlets from stochastic acceleration.

    PubMed

    Perri, Silvia; Carbone, Vincenzo

    2008-09-01

    We investigate the dynamics of a realization of the stochastic Fermi acceleration mechanism. The model consists of test particles moving between two oscillating magnetic clouds and differs from the usual Fermi-Ulam model in two ways. (i) Particles can penetrate inside clouds before being reflected. (ii) Particles can radiate a fraction of their energy during the process. Since the Fermi mechanism is at work, particles are stochastically accelerated, even in the presence of the radiated energy. Furthermore, due to a kind of resonance between particles and oscillating clouds, the probability density function of particles is strongly modified, thus generating beams of accelerated particles rather than a translation of the whole distribution function to higher energy. This simple mechanism could account for the presence of beamlets in some space plasma physics situations.

  2. 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.

  3. Accelerated Achievement

    ERIC Educational Resources Information Center

    Ford, William J.

    2010-01-01

    This article focuses on the accelerated associate degree program at Ivy Tech Community College (Indiana) in which low-income students will receive an associate degree in one year. The three-year pilot program is funded by a $2.3 million grant from the Lumina Foundation for Education in Indianapolis and a $270,000 grant from the Indiana Commission…

  4. ACCELERATION INTEGRATOR

    DOEpatents

    Pope, K.E.

    1958-01-01

    This patent relates to an improved acceleration integrator and more particularly to apparatus of this nature which is gyrostabilized. The device may be used to sense the attainment by an airborne vehicle of a predetermined velocitv or distance along a given vector path. In its broad aspects, the acceleration integrator utilizes a magnetized element rotatable driven by a synchronous motor and having a cylin drical flux gap and a restrained eddy- current drag cap deposed to move into the gap. The angular velocity imparted to the rotatable cap shaft is transmitted in a positive manner to the magnetized element through a servo feedback loop. The resultant angular velocity of tae cap is proportional to the acceleration of the housing in this manner and means may be used to measure the velocity and operate switches at a pre-set magnitude. To make the above-described dcvice sensitive to acceleration in only one direction the magnetized element forms the spinning inertia element of a free gyroscope, and the outer housing functions as a gimbal of a gyroscope.

  5. Plasma accelerator

    DOEpatents

    Wang, Zhehui; Barnes, Cris W.

    2002-01-01

    There has been invented an apparatus for acceleration of a plasma having coaxially positioned, constant diameter, cylindrical electrodes which are modified to converge (for a positive polarity inner electrode and a negatively charged outer electrode) at the plasma output end of the annulus between the electrodes to achieve improved particle flux per unit of power.

  6. Compact accelerator

    DOEpatents

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    2007-02-06

    A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).

  7. 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].

  8. Magnetic properties after irradiation of 1:4 complexes consisting of CoX2, X=NCS⁻, Cl⁻, and NCO⁻, and phenylpyridyldiazomethane in dilute frozen solutions: axial ligand effect in heterospin single-molecule magnets.

    PubMed

    Karasawa, Satoru; Koga, Noboru

    2011-06-01

    The solutions of 1:4 complexes of Co(X)(2)(D1py)(4), X = Cl(-), and NCO(-) and D1py = phenylpyridyldiazomethane, were photolyzed under cryogenic conditions, and their magnetic properties were investigated by direct current (DC) and alternating current (AC) magneto/susceptometries. After irradiation, the resulting cobalt-carbene complexes, Co(X)(2)(C1py)(4), exhibited the behaviors of heterospin single-molecule magnets (SMMs) strongly depending on the axial ligands. In Co(X)(2)(C1py)(4): X = Cl(-) and NCO(-), the effective activation barriers, U(eff), for the reorientation of the magnetic moment and the resonant quantum tunneling time, τ(Q), characteristic to SMM properties were estimated to be 91 and 130 K, and 4 × 10(3) and 2 × 10(5) s, respectively. The τ(Q) of Co(NCS)(2)(C1py)(4) with U(eff) = 89 K was found to be 6 × 10(2) s. In Co(X)(2)(C1py)(4): X = Cl(-) and NCO(-), temperature-dependent hysteresis loops were also observed below the blocking temperature (T(B) = 3.2 and 4.8 K, respectively) and the coercive forces, H(c), of 7.0 and 20 kOe at 1.9 K, respectively, were obtained. In a series of 1:4 complexes of Co(X)(2)(C1py)(4), X = NCS(-), Cl(-), and NCO(-), the axial ligands strongly affected the heterospin SMM properties, and the NCO(-) ion having the large magnitude of the ligand-field splitting in a spectrochemical series, gave the largest U(eff) and H(c) and the longest τ(Q).

  9. Advanced concepts for acceleration

    SciTech Connect

    Keefe, D.

    1986-07-01

    Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations. (LEW)

  10. Accelerators and the Accelerator Community

    SciTech Connect

    Malamud, Ernest; Sessler, Andrew

    2008-06-01

    In this paper, standing back--looking from afar--and adopting a historical perspective, the field of accelerator science is examined. How it grew, what are the forces that made it what it is, where it is now, and what it is likely to be in the future are the subjects explored. Clearly, a great deal of personal opinion is invoked in this process.

  11. Acceleration during magnetic reconnection

    SciTech Connect

    Beresnyak, Andrey; Li, Hui

    2015-07-16

    The presentation begins with colorful depictions of solar x-ray flares and references to pulsar phenomena. Plasma reconnection is complex, could be x-point dominated or turbulent, field lines could break due to either resistivity or non-ideal effects, such as electron pressure anisotropy. Electron acceleration is sometimes observed, and sometimes not. One way to study this complex problem is to have many examples of the process (reconnection) and compare them; the other way is to simplify and come to something robust. Ideal MHD (E=0) turbulence driven by magnetic energy is assumed, and the first-order acceleration is sought. It is found that dissipation in big (length >100 ion skin depths) current sheets is universal and independent on microscopic resistivity and the mean imposed field; particles are regularly accelerated while experiencing curvature drift in flows driven by magnetic tension. One example of such flow is spontaneous reconnection. This explains hot electrons with a power-law tail in solar flares, as well as ultrashort time variability in some astrophysical sources.

  12. A complex of YlbF, YmcA and YaaT regulates sporulation, competence and biofilm formation by accelerating the phosphorylation of Spo0A

    PubMed Central

    Carabetta, Valerie J.; Tanner, Andrew W.; Greco, Todd M.; Defrancesco, Melissa; Cristea, Ileana M.; Dubnau, David

    2013-01-01

    Summary Bacillus subtilis has adopted a bet-hedging strategy to ensure survival in changing environments. From a clonal population, numerous sub-populations can emerge, expressing different sets of genes that govern the developmental processes of sporulation, competence and biofilm formation. The master transcriptional regulator Spo0A controls the entry into all three fates and the production of the phosphorylated active form of Spo0A is precisely regulated via a phosphorelay, involving at least four proteins. Two proteins, YmcA and YlbF were previously shown to play an unidentified role in the regulation of biofilm formation, and in addition, YlbF was shown to regulate competence and sporulation. Using an unbiased proteomics screen, we demonstrate that YmcA and YlbF interact with a third protein, YaaT to form a tripartite complex. We show that all three proteins are required for proper establishment of the three above-mentioned developmental states. We show that the complex regulates the activity of Spo0A in vivo and, using in vitro reconstitution experiments, determine that they stimulate the phosphorelay, probably by interacting with Spo0F and Spo0B. We propose that the YmcA-YlbF-YaaT ternary complex is required to increase Spo0A~P levels above the thresholds needed to induce development. PMID:23490197

  13. Self-consistent flattened isochrones

    NASA Astrophysics Data System (ADS)

    Binney, James

    2014-05-01

    We present a family of self-consistent axisymmetric stellar systems that have analytic distribution functions (DFs) of the form f(J), so they depend on three integrals of motion and have triaxial velocity ellipsoids. The models, which are generalizations of Hénon's isochrone sphere, have four dimensionless parameters, two determining the part of the DF that is even in Lz and two determining the odd part of the DF (which determines the azimuthal velocity distribution). Outside their cores, the velocity ellipsoids of all models tend to point to the model's centre, and we argue that this behaviour is generic, so near the symmetry axis of a flattened model, the long axis of the velocity ellipsoid is naturally aligned with the symmetry axis and not perpendicular to it as in many published dynamical models of well-studied galaxies. By varying one of the DF parameters, the intensity of rotation can be increased from zero up to a maximum value set by the requirement that the DF be non-negative. Since angle-action coordinates are easily computed for these models, they are ideally suited for perturbative treatments and stability analysis. They can also be used to choose initial conditions for an N-body model that starts in perfect equilibrium, and to model observations of early-type galaxies. The modelling technique introduced here is readily extended to different radial density profiles, more complex kinematics and multicomponent systems. A number of important technical issues surrounding the determination of the models' observable properties are explained in two appendices.

  14. High-throughput Ru(III) analysis using the hydrothermal flow reactor-mediated FIA by the extreme acceleration of Ru(III) complexation with 1,10-phenanthroline.

    PubMed

    Kawamura, Kunio; Nakai, Takayuki; Ikoma, Keisuke; Hisamoto, Hideaki

    2012-09-15

    A new type of flow injection analysis (FIA) combined with a high-temperature reactor maintained at 100-400 °C, namely hydrothermal flow injection analysis (HT-FIA), has been successfully applied to high throughput determination of Ru(III) on the basis of a conventional chromogenic reaction with 1,10-phenothroline (phen). Although this classical chromogenic reaction using phen is sensitive and selective for Ru(III), the complex formation of Ru(phen)(3) requires 2 h. The acceleration using HT-FIA is extraordinary high so that the determination reaction of Ru(III) was successfully shortened to 5 s at 150 °C, where the analytical procedure was accelerated more than 1000-fold. This enabled a high-throughput analysis of Ru(III) with 100 μL sample, of which at least 10 samples can be analyzed within 10 min. The detection limit of Ru(III) determined on the basis of 3 times of standard deviation was 5.3×10(-7) M (53 pmol or 5.4 ng Ru in 100 μL sample). The present study emphasizes the importance of the revival of classical chromogenic reactions, which are potentially valuable but not regarded anymore as useful because they are time-consuming and tedious, to fit for the demand for environmentally harmless analytical techniques.

  15. Radiation from Shock-Accelerated Particles

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-ichi; Choi, E. J.; Min, K. W.; Niemiec, J.; Zhang, B.; Hardee, P.; Mizuno, Y.; Medvedev, M.; Nordlund, A.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Fishman, G. J.

    2012-01-01

    Plasma instabilities excited in collisionless shocks are responsible for particle acceleration, generation of magnetic fields , and associated radiation. We have investigated the particle acceleration and shock structure associated with an unmagnetized relativistic jet propagating into an unmagnetized plasma. Cold jet electrons are thermalized and slowed while the ambient electrons are swept up to create a partially developed hydrodynamic-like shock structure. The shock structure depends on the composition of the jet and ambient plasma (electron-positron or electron-ions). Strong electromagnetic fields are generated in the reverse , jet shock and provide an emission site. These magnetic fields contribute to the electron's transverse deflection behind the shock. We have calculated, self-consistently, the radiation from electrons accelerated in the turbulent magnetic fields. We found that the synthetic spectra depend on the Lorentz factor of the jet, its thermal temperature and strength of the generated magnetic fields. The detailed properties of the radiation are important for understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jet shocks, and supernova remnants

  16. Accelerator research studies

    SciTech Connect

    Not Available

    1992-01-01

    The Accelerator Research Studies program at the University of Maryland, sponsored by the Department of Energy under grant number DE-FG05-91ER40642, is currently in the first year of a three-year funding cycle. The program consists of the following three tasks: TASK A, Study of Transport and Longitudinal Compression of Intense, High-Brightness Beams, TASK B, Study of Collective Ion Acceleration by Intense Electron Beams and Pseudospark Produced High Brightness Electron Beams; TASK C, Study of a Gyroklystron High-power Microwave Source for Linear Colliders. In this report we document the progress that has been made during the past year for each of the three tasks.

  17. EM Structure Based and Vacuum Acceleration

    SciTech Connect

    Colby, E.R.; /SLAC

    2005-09-27

    The importance of particle acceleration may be judged from the number of applications which require some sort of accelerated beam. In addition to accelerator-based high energy physics research, non-academic applications include medical imaging and treatment, structural biology by x-ray diffraction, pulse radiography, cargo inspection, material processing, food and medical instrument sterilization, and so on. Many of these applications are already well served by existing technologies and will profit only marginally from developments in accelerator technology. Other applications are poorly served, such as structural biology, which is conducted at synchrotron radiation facilities, and medical treatment using proton accelerators, the machines for which are rare because they are complex and costly. Developments in very compact, high brightness and high gradient accelerators will change how accelerators are used for such applications, and potentially enable new ones. Physical and technical issues governing structure-based and vacuum acceleration of charged particles are reviewed, with emphasis on practical aspects.

  18. Accelerator system and method of accelerating particles

    NASA Technical Reports Server (NTRS)

    Wirz, Richard E. (Inventor)

    2010-01-01

    An accelerator system and method that utilize dust as the primary mass flux for generating thrust are provided. The accelerator system can include an accelerator capable of operating in a self-neutralizing mode and having a discharge chamber and at least one ionizer capable of charging dust particles. The system can also include a dust particle feeder that is capable of introducing the dust particles into the accelerator. By applying a pulsed positive and negative charge voltage to the accelerator, the charged dust particles can be accelerated thereby generating thrust and neutralizing the accelerator system.

  19. Rare Kaon Decays, KEK experiment E391 and E14 at the Japan Physics and Accelerator Research Complex (J-PARC)

    SciTech Connect

    Wah, Yau Wai

    2012-12-06

    The goal of the J-PARC neutral kaon experiment (E14/KOTO) is to discover and measure the rate of the kaon rare decay to pi-zero and two neutrinos. This flavor changing neutral current decay proceeds through second-order weak interactions. Other, as yet undiscovered particles, which can mediate the decay could provide an enhancement (or depletion) to the branching ratio which in the Standard Model is accurately predicted within a few percent to be 2.8x10-11. The experiment is designed to observe more than 100 events at the Standard Model branching. It is a follow-up of the KEK E391a experiment and has stage-2 approval by J-PARC PAC in 2007. E14/KOTO has collaborators from Japan (Kyoto, Osaka, Yamagata, Saga), US (Arizona State, Chicago, Michigan Ann Arbor), Taiwan (National Taiwan), Korea, and Russia (Dubna). The experiment exploits the 300kW 30-50 GeV proton delivery of the J-PARC accelerator with a hermetic high acceptance detector with a fine grained Cesium Iodide (CsI) crystal calorimeter, and state of the art electronic front end and data acquisition system. With the recovery of the tsunami disaster on March 11th 2011, E14 is scheduled to start collecting data in December 2012. During the detector construction phase, Chicago focuses on the front end electronics readout of the entire detector system, particularly the CsI calorimeter. The CsI crystals together with its photomultipliers were previously used at the Fermilab KTeV experiment (E832/E799), and were loaned to E14 via this Chicago DOE support. The new readout electronics includes an innovative 10-pole pulse-shaping technique coupled with high speed digitization (14-bit 125MHz and 12-bit 500MHz). This new instrument enables us to measure both energy and timing, particularly with timing resolution better than 100 psec. Besides the cost saving by elimination of the standard time to digital converters, it is now possible to measure the momenta of the final state photons for additional background suppression

  20. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1995-01-01

    The application of electric propulsion to communications satellites, however, has been limited to the use of hydrazine thrusters with electric heaters for thrust and specific impulse augmentation. These electrothermal thrusters operate at specific impulse levels of approximately 300 s with heater powers of about 500 W. Low power arcjets (1-3 kW) are currently being investigated as a way to increase specific impulse levels to approximately 500 s. Ion propulsion systems can easily produce specific impulses of 3000 s or greater, but have yet to be applied to communications satellites. The reasons most often given for not using ion propulsion systems are their high level of overall complexity, low thrust with long burn times, and the difficulty of integrating the propulsion system into existing commercial spacecraft busses. The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass.

  1. Radiation from Accelerated Particles in Shocks and Reconnections

    NASA Technical Reports Server (NTRS)

    Nishikawa, K. I.; Choi, E. J.; Min, K. W.; Niemiec, J.; Zhang, B.; Hardee, P.; Mizuno, Y.; Medvedev, M.; Nordlund, A.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Fishman, G. J.

    2012-01-01

    Plasma instabilities are responsible not only for the onset and mediation of collisionless shocks but also for the associated acceleration of particles. We have investigated particle acceleration and shock structure associated with an unmagnetized relativistic electron-positron jet propagating into an unmagnetized electron-positron plasma. Cold jet electrons are thermalized and slowed while the ambient electrons are swept up to create a partially developed hydrodynamic-like shock structure. In the leading shock, electron density increases by a factor of about 3.5 in the simulation frame. Strong electromagnetic fields are generated in the trailing shock and provide an emission site. These magnetic fields contribute to the electrons transverse deflection and, more generally, relativistic acceleration behind the shock. We have calculated, self-consistently, the radiation from electrons accelerated in the turbulent magnetic fields. We found that the synthetic spectra depend on the Lorentz factor of the jet, its thermal temperature and strength of the generated magnetic fields. Our initial results of a jet-ambient interaction with anti-parallelmagnetic fields show pile-up of magnetic fields at the colliding shock, which may lead to reconnection and associated particle acceleration. We will investigate the radiation in a transient stage as a possible generation mechanism of precursors of prompt emission. In our simulations we calculate the radiation from electrons in the shock region. The detailed properties of this radiation are important for understanding the complex time evolution and spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  2. Modeling magnetic field amplification in nonlinear diffusive shock acceleration

    NASA Astrophysics Data System (ADS)

    Vladimirov, Andrey

    2009-02-01

    This research was motivated by the recent observations indicating very strong magnetic fields at some supernova remnant shocks, which suggests in-situ generation of magnetic turbulence. The dissertation presents a numerical model of collisionless shocks with strong amplification of stochastic magnetic fields, self-consistently coupled to efficient shock acceleration of charged particles. Based on a Monte Carlo simulation of particle transport and acceleration in nonlinear shocks, the model describes magnetic field amplification using the state-of-the-art analytic models of instabilities in magnetized plasmas in the presence of non-thermal particle streaming. The results help one understand the complex nonlinear connections between the thermal plasma, the accelerated particles and the stochastic magnetic fields in strong collisionless shocks. Also, predictions regarding the efficiency of particle acceleration and magnetic field amplification, the impact of magnetic field amplification on the maximum energy of accelerated particles, and the compression and heating of the thermal plasma by the shocks are presented. Particle distribution functions and turbulence spectra derived with this model can be used to calculate the emission of observable nonthermal radiation.

  3. TRACKING ACCELERATOR SETTINGS.

    SciTech Connect

    D OTTAVIO,T.; FU, W.; OTTAVIO, D.P.

    2007-10-15

    Recording setting changes within an accelerator facility provides information that can be used to answer questions about when, why, and how changes were made to some accelerator system. This can be very useful during normal operations, but can also aid with security concerns and in detecting unusual software behavior. The Set History System (SHS) is a new client-server system developed at the Collider-Accelerator Department of Brookhaven National Laboratory to provide these capabilities. The SHS has been operational for over two years and currently stores about IOOK settings per day into a commercial database management system. The SHS system consists of a server written in Java, client tools written in both Java and C++, and a web interface for querying the database of setting changes. The design of the SHS focuses on performance, portability, and a minimal impact on database resources. In this paper, we present an overview of the system design along with benchmark results showing the performance and reliability of the SHS over the last year.

  4. Berkeley Proton Linear Accelerator

    DOE R&D Accomplishments Database

    Alvarez, L. W.; Bradner, H.; Franck, J.; Gordon, H.; Gow, J. D.; Marshall, L. C.; Oppenheimer, F. F.; Panofsky, W. K. H.; Richman, C.; Woodyard, J. R.

    1953-10-13

    A linear accelerator, which increases the energy of protons from a 4 Mev Van de Graaff injector, to a final energy of 31.5 Mev, has been constructed. The accelerator consists of a cavity 40 feet long and 39 inches in diameter, excited at resonance in a longitudinal electric mode with a radio-frequency power of about 2.2 x 10{sup 6} watts peak at 202.5 mc. Acceleration is made possible by the introduction of 46 axial "drift tubes" into the cavity, which is designed such that the particles traverse the distance between the centers of successive tubes in one cycle of the r.f. power. The protons are longitudinally stable as in the synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids. The electrical cavity is constructed like an inverted airplane fuselage and is supported in a vacuum tank. Power is supplied by 9 high powered oscillators fed from a pulse generator of the artificial transmission line type.

  5. Accelerators for Intensity Frontier Research

    SciTech Connect

    Derwent, Paul; /Fermilab

    2012-05-11

    In 2008, the Particle Physics Project Prioritization Panel identified three frontiers for research in high energy physics, the Energy Frontier, the Intensity Frontier, and the Cosmic Frontier. In this paper, I will describe how Fermilab is configuring and upgrading the accelerator complex, prior to the development of Project X, in support of the Intensity Frontier.

  6. Bio-nano complexes of ZVFeNPs/Fe-s-M13 and Cd (II)/Cd-s-M13 accelerate Cd (II) reduction by FeNPs through dual dispersing and separate deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Nakano, Kazuhiko; Yu, Huimin; Shen, Zhongyao

    2014-03-01

    Reduction of Cd (II) in liquor by solid zero valent Fe nanoparticles (ZVFeNPs) is a liquid-solid biphasic reaction in which the reduction efficiency was often lowered by either aggregation of ZVFeNPs or coating of the generated ZVCd. In light of the filamentous nanostructure of bacteriophage M13 with ˜2700 copies of pVIII protein in delicate distribution at the coat, a novel dual dispersing reduction route was designed by introducing two different kinds of M13 with Fe-binding specificity (Fe-s-M13) and Cd-binding specificity (Cd-s-M13) to disperse ZVFeNPs and Cd (II) ions, respectively. The Fe-s-M13 was used for synthesis of the ZVFeNPs/Fe-s-M13 complex, where ZVFeNPs were uniformly dispersed into small nanoparticles (5-10 nm) on Fe-s-M13. The engineered Cd-s-M13, constructed by genetic recombination of pVIII through inserting the gene of a biopanned 7-mer Cd-specific peptide (SCPICPG) into the N-terminus of pVIII gene, was used for Cd (II) dispersion before reduction. The dispersed complex of Cd(II)/Cd-s-M13 was rapidly reduced by complex of ZVFeNPs/Fe-s-M13. Kinetics results showed that the initial reduction rate and final reduction ratio of Cd (II) increased by 35.7% and 16.4%, respectively, through dispersion of ZVFeNPs by Fe-s-M13; they improved again by 53.6% and 37.0%, respectively, through further dispersion of Cd (II) by Cd-s-M13. TEM and EDS results revealed that the acceleration effect of the dual dispersing reduction was arising from uniform dispersion of the small ZVFeNPs and separate deposition of the reduced ZVCd on the two different M13 phages.

  7. Consistency tests for the cosmological constant.

    PubMed

    Zunckel, Caroline; Clarkson, Chris

    2008-10-31

    We propose consistency tests for the cosmological constant which provide a direct observational signal if Lambda is wrong, regardless of the densities of matter and curvature. As an example of its utility, our flat case test can warn of a small transition of the equation of state w(z) from w(z)=-1 of 20% from SNAP (Supernova Acceleration Probe) quality data at 4-sigma, even when direct reconstruction techniques see virtually no evidence for deviation from Lambda. It is shown to successfully rule out a wide range of non-Lambda dark energy models with no reliance on knowledge of Omega_{m} using SNAP quality data and a large range for using 10;{5} supernovae as forecasted for the Large Synoptic Survey Telescope. PMID:18999813

  8. Space Experiments with Particle Accelerators (SEPAC)

    NASA Technical Reports Server (NTRS)

    Roberts, W. T.

    1985-01-01

    The space experiments with particle accelerators (SEPAC) instruments consist of an electron accelerator, a plasma accelerator, a neutral gas (N2) release device, particle and field diagnostic instruments, and a low light level television system. These instruments are used to accomplish multiple experiments: to study beam particle interactions and other plasma processes; as probes to investigate magnetospheric processes; and as perturbation devices to study energy coupling mechanisms in the magnetosphere, ionosphere, and upper atmosphere.

  9. Measurement of Coriolis Acceleration with a Smartphone

    ERIC Educational Resources Information Center

    Shaku, Asif; Kraft, Jakob

    2016-01-01

    Undergraduate physics laboratories seldom have experiments that measure the Coriolis acceleration. This has traditionally been the case owing to the inherent complexities of making such measurements. Articles on the experimental determination of the Coriolis acceleration are few and far between in the physics literature. However, because modern…

  10. Consistency check of photon beam physical data after recommissioning process

    NASA Astrophysics Data System (ADS)

    Kadman, B.; Chawapun, N.; Ua-apisitwong, S.; Asakit, T.; Chumpu, N.; Rueansri, J.

    2016-03-01

    In radiotherapy, medical linear accelerator (Linac) is the key system used for radiation treatments delivery. Although, recommissioning was recommended after major modification of the machine by AAPM TG53, but it might not be practical in radiotherapy center with heavy workloads. The main purpose of this study was to compare photon beam physical data between initial commissioning and recommissioning of 6 MV Elekta Precise linac. The parameters for comparing were the percentage depth dose (PDD) and beam profiles. The clinical commissioning test cases followed IAEA-TECDOC-1583 were planned on REF 91230 IMRT Dose Verification Phantom by Philips’ Pinnacle treatment planning system. The Delta4PT was used for dose distribution verification with 90% passing criteria of the gamma index (3%/3mm). Our results revealed that the PDDs and beam profiles agreed within a tolerance limit recommended by TRS430. Most of the point doses and dose distribution verification passed the acceptance criteria. This study showed the consistency of photon beam physical data after recommissioning process. There was a good agreement between initial commissioning and recommissioning within a tolerance limit, demonstrated that the full recommissioning process might not be required. However, in the complex treatment planning geometry, the initial data should be applied with great caution.

  11. Quantifying the Consistency of Scientific Databases

    PubMed Central

    Šubelj, Lovro; Bajec, Marko; Mileva Boshkoska, Biljana; Kastrin, Andrej; Levnajić, Zoran

    2015-01-01

    Science is a social process with far-reaching impact on our modern society. In recent years, for the first time we are able to scientifically study the science itself. This is enabled by massive amounts of data on scientific publications that is increasingly becoming available. The data is contained in several databases such as Web of Science or PubMed, maintained by various public and private entities. Unfortunately, these databases are not always consistent, which considerably hinders this study. Relying on the powerful framework of complex networks, we conduct a systematic analysis of the consistency among six major scientific databases. We found that identifying a single "best" database is far from easy. Nevertheless, our results indicate appreciable differences in mutual consistency of different databases, which we interpret as recipes for future bibliometric studies. PMID:25984946

  12. The Principle of Energetic Consistency

    NASA Technical Reports Server (NTRS)

    Cohn, Stephen E.

    2009-01-01

    A basic result in estimation theory is that the minimum variance estimate of the dynamical state, given the observations, is the conditional mean estimate. This result holds independently of the specifics of any dynamical or observation nonlinearity or stochasticity, requiring only that the probability density function of the state, conditioned on the observations, has two moments. For nonlinear dynamics that conserve a total energy, this general result implies the principle of energetic consistency: if the dynamical variables are taken to be the natural energy variables, then the sum of the total energy of the conditional mean and the trace of the conditional covariance matrix (the total variance) is constant between observations. Ensemble Kalman filtering methods are designed to approximate the evolution of the conditional mean and covariance matrix. For them the principle of energetic consistency holds independently of ensemble size, even with covariance localization. However, full Kalman filter experiments with advection dynamics have shown that a small amount of numerical dissipation can cause a large, state-dependent loss of total variance, to the detriment of filter performance. The principle of energetic consistency offers a simple way to test whether this spurious loss of variance limits ensemble filter performance in full-blown applications. The classical second-moment closure (third-moment discard) equations also satisfy the principle of energetic consistency, independently of the rank of the conditional covariance matrix. Low-rank approximation of these equations offers an energetically consistent, computationally viable alternative to ensemble filtering. Current formulations of long-window, weak-constraint, four-dimensional variational methods are designed to approximate the conditional mode rather than the conditional mean. Thus they neglect the nonlinear bias term in the second-moment closure equation for the conditional mean. The principle of

  13. An MCNPX accelerator beam source

    SciTech Connect

    Durkee, Joe W.; Elson, Jay S.; Jason, Andrew; Johns, Russell C.; Waters, Laurie S.

    2009-06-04

    MCNPX is a powerful Monte Carlo code that can be used to conduct sophisticated radiation-transport simulations involving complex physics and geometry. Although MCNPX possesses a wide assortment of standardized modeling tools, there are instances in which a user's needs can eclipse existing code capabilities. Fortunately, although it may not be widely known, MCNPX can accommodate many customization needs. In this article, we demonstrate source-customization capability for a new SOURCE subroutine as part of our development to enable simulations involving accelerator beams for active-interrogation studies. Simulation results for a muon beam are presented to illustrate the new accelerator-source capability.

  14. Beam loss caused by edge focusing of injection bump magnets and its mitigation in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

    NASA Astrophysics Data System (ADS)

    Hotchi, H.; Tani, N.; Watanabe, Y.; Harada, H.; Kato, S.; Okabe, K.; Saha, P. K.; Tamura, F.; Yoshimoto, M.

    2016-01-01

    In the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex, transverse injection painting is utilized not only to suppress space-charge induced beam loss in the low energy region but also to mitigate foil scattering beam loss during charge-exchange injection. The space-charge induced beam loss is well minimized by the combination of modest transverse painting and full longitudinal painting. But, for sufficiently mitigating the foil scattering part of beam loss, the transverse painting area has to be further expanded. However, such a wide-ranging transverse painting had not been realized until recently due to beta function beating caused by edge focusing of pulsed injection bump magnets during injection. This beta function beating additionally excites random betatron resonances through a distortion of the lattice superperiodicity, and its resultant deterioration of the betatron motion stability causes significant extra beam loss when expanding the transverse painting area. To solve this issue, we newly installed pulse-type quadrupole correctors to compensate the beta function beating. This paper presents recent experimental results on this correction scheme for suppressing the extra beam loss, while discussing the beam loss and its mitigation mechanisms with the corresponding numerical simulations.

  15. Epipolar Consistency in Transmission Imaging.

    PubMed

    Aichert, André; Berger, Martin; Wang, Jian; Maass, Nicole; Doerfler, Arnd; Hornegger, Joachim; Maier, Andreas K

    2015-11-01

    This paper presents the derivation of the Epipolar Consistency Conditions (ECC) between two X-ray images from the Beer-Lambert law of X-ray attenuation and the Epipolar Geometry of two pinhole cameras, using Grangeat's theorem. We motivate the use of Oriented Projective Geometry to express redundant line integrals in projection images and define a consistency metric, which can be used, for instance, to estimate patient motion directly from a set of X-ray images. We describe in detail the mathematical tools to implement an algorithm to compute the Epipolar Consistency Metric and investigate its properties with detailed random studies on both artificial and real FD-CT data. A set of six reference projections of the CT scan of a fish were used to evaluate accuracy and precision of compensating for random disturbances of the ground truth projection matrix using an optimization of the consistency metric. In addition, we use three X-ray images of a pumpkin to prove applicability to real data. We conclude, that the metric might have potential in applications related to the estimation of projection geometry. By expression of redundancy between two arbitrary projection views, we in fact support any device or acquisition trajectory which uses a cone-beam geometry. We discuss certain geometric situations, where the ECC provide the ability to correct 3D motion, without the need for 3D reconstruction. PMID:25915956

  16. Averaging Internal Consistency Reliability Coefficients

    ERIC Educational Resources Information Center

    Feldt, Leonard S.; Charter, Richard A.

    2006-01-01

    Seven approaches to averaging reliability coefficients are presented. Each approach starts with a unique definition of the concept of "average," and no approach is more correct than the others. Six of the approaches are applicable to internal consistency coefficients. The seventh approach is specific to alternate-forms coefficients. Although the…

  17. Community Petascale Project for Accelerator Science and Simulation: Advancing Computational Science for Future Accelerators and Accelerator Technologies

    SciTech Connect

    Spentzouris, P.; Cary, J.; McInnes, L.C.; Mori, W.; Ng, C.; Ng, E.; Ryne, R.; /LBL, Berkeley

    2011-11-14

    The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors. ComPASS is in the first year of executing its plan to develop the next-generation HPC accelerator modeling tools. ComPASS aims to develop an integrated simulation environment that will utilize existing and new accelerator physics modules with petascale capabilities, by employing modern computing and solver technologies. The ComPASS vision is to deliver to accelerator scientists a virtual accelerator and virtual prototyping modeling environment, with the necessary multiphysics, multiscale capabilities. The plan for this development includes delivering accelerator modeling applications appropriate for each stage of the ComPASS software evolution. Such applications are already being used to address challenging problems in accelerator design and optimization. The ComPASS organization

  18. Three stages of the NICA accelerator complex

    NASA Astrophysics Data System (ADS)

    Kekelidze, V. D.; Lednicky, R.; Matveev, V. A.; Meshkov, I. N.; Sorin, A. S.; Trubnikov, G. V.

    2016-08-01

    The Nuclotron-based Ion Collider fAcility (NICA) project is under development at JINR (Dubna). The general goals of the project are to provide colliding beams for experimental studies of both hot and dense strongly interacting baryonic matter and spin physics (in collisions of polarized protons and deuterons). The first program will require the running of heavy-ion mode in the energy range of √{s_{NN}} = 4-11 GeV at luminosities up to L = 1\\cdot 10^{27} cm-2 s-1 for 197Au79 nuclei (see details in sect. 4). This stage of the project will be preceded by fixed target experiments with the heavy-ion beam to be extracted from the Nuclotron at kinetic energies up to 4.5 GeV/u. The polarized beam mode is proposed to be used in the energy range of √{s_{NN}} = 12-27 GeV (protons) at luminosities up to 1\\cdot 10^{32} cm-2 s-1. This report contains a brief description of the facility scheme and characteristics in the heavy-ion operation mode, the description of the MultiPurpose Detector (MPD), and characteristics of the reactions of the colliding ions, which will allow us to detect the mixed phase formation. The plans and status of the project development are presented.

  19. APT accelerator. Topical report

    SciTech Connect

    Lawrence, G.; Rusthoi, D.

    1995-03-01

    The Accelerator Production of Tritium (APT) project, sponsored by Department of Energy Defense Programs (DOE/DP), involves the preconceptual design of an accelerator system to produce tritium for the nation`s stockpile of nuclear weapons. Tritium is an isotope of hydrogen used in nuclear weapons, and must be replenished because of radioactive decay (its half-life is approximately 12 years). Because the annual production requirements for tritium has greatly decreased since the end of the Cold War, an alternative approach to reactors for tritium production, based on a linear accelerator, is now being seriously considered. The annual tritium requirement at the time this study was undertaken (1992-1993) was 3/8 that of the 1988 goal, usually stated as 3/8-Goal. Continued reduction in the number of weapons in the stockpile has led to a revised (lower) production requirement today (March, 1995). The production requirement needed to maintain the reduced stockpile, as stated in the recent Nuclear Posture Review (summer 1994) is approximately 3/16-Goal, half the previous level. The Nuclear Posture Review also requires that the production plant be designed to accomodate a production increase (surge) to 3/8-Goal capability within five years, to allow recovery from a possible extended outage of the tritium plant. A multi-laboratory team, collaborating with several industrial partners, has developed a preconceptual APT design for the 3/8-Goal, operating at 75% capacity. The team has presented APT as a promising alternative to the reactor concepts proposed for Complex-21. Given the requirements of a reduced weapons stockpile, APT offers both significant safety, environmental, and production-fexibility advantages in comparison with reactor systems, and the prospect of successful development in time to meet the US defense requirements of the 21st Century.

  20. Conceptual design of industrial free electron laser using superconducting accelerator

    SciTech Connect

    Saldin, E.L.; Schneidmiller, E.A.; Ulyanov, Yu.N.

    1995-12-31

    Paper presents conceptual design of free electron laser (FEL) complex for industrial applications. The FEL complex consists of three. FEL oscillators with the optical output spanning the infrared (IR) and ultraviolet (UV) wave-lengths ({lambda} = 0.3...20 {mu}m) and with the average output power 10 - 20 kW. The driving beam for the FELs is produced by a superconducting accelerator. The electron beam is transported to the FELs via three beam lines (125 MeV and 2 x 250 MeV). Peculiar feature of the proposed complex is a high efficiency of the. FEL oscillators, up to 20 %. This becomes possible due to the use of quasi-continuous electron beam and the use of the time-dependent undulator tapering.

  1. Laser driven ion accelerator

    DOEpatents

    Tajima, Toshiki

    2006-04-18

    A system and method of accelerating ions in an accelerator to optimize the energy produced by a light source. Several parameters may be controlled in constructing a target used in the accelerator system to adjust performance of the accelerator system. These parameters include the material, thickness, geometry and surface of the target.

  2. Accelerator science in medical physics.

    PubMed

    Peach, K; Wilson, P; Jones, B

    2011-12-01

    The use of cyclotrons and synchrotrons to accelerate charged particles in hospital settings for the purpose of cancer therapy is increasing. Consequently, there is a growing demand from medical physicists, radiographers, physicians and oncologists for articles that explain the basic physical concepts of these technologies. There are unique advantages and disadvantages to all methods of acceleration. Several promising alternative methods of accelerating particles also have to be considered since they will become increasingly available with time; however, there are still many technical problems with these that require solving. This article serves as an introduction to this complex area of physics, and will be of benefit to those engaged in cancer therapy, or who intend to acquire such technologies in the future.

  3. Accelerator science in medical physics

    PubMed Central

    Peach, K; Wilson, P; Jones, B

    2011-01-01

    The use of cyclotrons and synchrotrons to accelerate charged particles in hospital settings for the purpose of cancer therapy is increasing. Consequently, there is a growing demand from medical physicists, radiographers, physicians and oncologists for articles that explain the basic physical concepts of these technologies. There are unique advantages and disadvantages to all methods of acceleration. Several promising alternative methods of accelerating particles also have to be considered since they will become increasingly available with time; however, there are still many technical problems with these that require solving. This article serves as an introduction to this complex area of physics, and will be of benefit to those engaged in cancer therapy, or who intend to acquire such technologies in the future. PMID:22374548

  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. Consistent transport coefficients in astrophysics

    NASA Technical Reports Server (NTRS)

    Fontenla, Juan M.; Rovira, M.; Ferrofontan, C.

    1986-01-01

    A consistent theory for dealing with transport phenomena in stellar atmospheres starting with the kinetic equations and introducing three cases (LTE, partial LTE, and non-LTE) was developed. The consistent hydrodynamical equations were presented for partial-LTE, the transport coefficients defined, and a method shown to calculate them. The method is based on the numerical solution of kinetic equations considering Landau, Boltzmann, and Focker-Planck collision terms. Finally a set of results for the transport coefficients derived for a partially ionized hydrogen gas with radiation was shown, considering ionization and recombination as well as elastic collisions. The results obtained imply major changes is some types of theoretical model calculations and can resolve some important current problems concerning energy and mass balance in the solar atmosphere. It is shown that energy balance in the lower solar transition region can be fully explained by means of radiation losses and conductive flux.

  6. Consistent interpretations of quantum mechanics

    SciTech Connect

    Omnes, R. )

    1992-04-01

    Within the last decade, significant progress has been made towards a consistent and complete reformulation of the Copenhagen interpretation (an interpretation consisting in a formulation of the experimental aspects of physics in terms of the basic formalism; it is consistent if free from internal contradiction and complete if it provides precise predictions for all experiments). The main steps involved decoherence (the transition from linear superpositions of macroscopic states to a mixing), Griffiths histories describing the evolution of quantum properties, a convenient logical structure for dealing with histories, and also some progress in semiclassical physics, which was made possible by new methods. The main outcome is a theory of phenomena, viz., the classically meaningful properties of a macroscopic system. It shows in particular how and when determinism is valid. This theory can be used to give a deductive form to measurement theory, which now covers some cases that were initially devised as counterexamples against the Copenhagen interpretation. These theories are described, together with their applications to some key experiments and some of their consequences concerning epistemology.

  7. Pros and Cons of the Acceleration Scheme (NF-IDS)

    SciTech Connect

    Bogacz, Alex; Bogacz, Slawomir

    2008-07-01

    The overall goal of the acceleration systems: large acceptance acceleration to 25 GeV and beam shaping can be accomplished by various fixed field accelerators at different stages. They involve three superconducting linacs: a single pass linear Pre-accelerator followed by a pair of multi-pass Recirculating Linear Accelerators (RLA) and finally a nonâ scaling FFAG ring. The present baseline acceleration scenario has been optimized to take maximum advantage of appropriate acceleration scheme at a given stage. Pros and cons of various stages are discussed here in detail. The solenoid based Pre-accelerator offers very large acceptance and facilitates correction of energy gain across the bunch and significant longitudinal compression trough induced synchrotron motion. However, far off-crest acceleration reduces the effective acceleration gradient and adds complexity through the requirement of individual RF phase control for each cavity. Close proximity of strong solenoids and superc

  8. Radiation from Accelerated Particles in Shocks and Reconnections

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Zhang, B.; Niemiec, J.; Medvedev, M.; Hardee, P.; Mizuno, Y.; Nordlund, A.; Frederiksen, J. T.; Sol, H.; Pohl, M.; Hartmann, D. H.; Fishman, G. J.

    2011-01-01

    Plasma instabilities are responsible not only for the onset and mediation of collisionless shocks but also for the associated acceleration of particles. We have investigated particle acceleration and shock structure associated with an unmagnetized relativistic electron-positron jet propagating into an unmagnetized electron-positron plasma. Cold jet electrons are thermalized and slowed while the ambient electrons are swept up to create a partially developed hydrodynamic-like shock structure. In the leading shock, electron density increases by a factor of about 3.5 in the simulation frame. Strong electromagnetic fields are generated in the trailing shock and provide an emission site. These magnetic fields contribute to the electrons transverse deflection and, more generally, relativistic acceleration behind the shock. We have calculated, self-consistently, the radiation from electrons accelerated in the turbulent magnetic fields. We found that the synthetic spectra depend on the Lorentz factor of the jet, its thermal temperature and strength of the generated magnetic fields. We are currently investigating the specific case of a jet colliding with an anti-parallel magnetized ambient medium. The properties of the radiation may be important for understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets in general, and supernova remnants.

  9. Accelerated life testing effects on CMOS microcircuit characteristics

    NASA Technical Reports Server (NTRS)

    1980-01-01

    This report covers the time period from May 1976 to December 1979 and encompasses the three phases of accelerated testing: Phase 1, the 250 C testing; Phase 2, the 200 C testing; and Phase 3, the 125 C testing. The duration of the test in Phase 1 and Phase 2 was sufficient to take the devices into the wear out region. The wear out distributions were used to estimate the activation energy between the 250 C and the 200 C test temperatures. The duration of the 125 C test, 20,000 hours, was not sufficient to bring the test devices into the wear out region; consequently the third data point at 125 C for determining the consistency of activation energy could not be obtained. It was estimated that, for the most complex of the three device types, the activation energy between 200 C and 125 C should be at least as high as that between 250 C and 200 C. The practicality of the use of high temperature for the accelerated life tests from the point of view of durability of equipment was assessed. Guidelines for the development of accelerated life test conditions were proposed. The use of the silicon nitride overcoat to improve the high temperature accelerated life test characteristics of CMOS microcircuits was explored in Phase 4 of this study and is attached as an appendix to this report.

  10. Pulsed Plasma Accelerator Modeling

    NASA Technical Reports Server (NTRS)

    Goodman, M.; Kazeminezhad, F.; Owens, T.

    2009-01-01

    This report presents the main results of the modeling task of the PPA project. The objective of this task is to make major progress towards developing a new computational tool with new capabilities for simulating cylindrically symmetric 2.5 dimensional (2.5 D) PPA's. This tool may be used for designing, optimizing, and understanding the operation of PPA s and other pulsed power devices. The foundation for this task is the 2-D, cylindrically symmetric, magnetohydrodynamic (MHD) code PCAPPS (Princeton Code for Advanced Plasma Propulsion Simulation). PCAPPS was originally developed by Sankaran (2001, 2005) to model Lithium Lorentz Force Accelerators (LLFA's), which are electrode based devices, and are typically operated in continuous magnetic field to the model, and implementing a first principles, self-consistent algorithm to couple the plasma and power circuit that drives the plasma dynamics.

  11. Consistent Two-Dimensional Chiral Gravity

    NASA Astrophysics Data System (ADS)

    Smailagic, A.; Spallucci, E.

    We study chiral induced gravity in the light-cone gauge and show that the theory is consistent for a particular choice of chiralities. The corresponding Kac-Moody central charge has no forbidden region of complex values. Generalized analysis of the critical exponents is given and their relation to the SL(2,R) vacuum states is elucidated. All the parameters containing information about the theory can be traced back to the characteristics of the residual symmetry group in the light-cone gauge.

  12. Dusty-Plasma Particle Accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2005-01-01

    A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the

  13. TURBULENT SHEAR ACCELERATION

    SciTech Connect

    Ohira, Yutaka

    2013-04-10

    We consider particle acceleration by large-scale incompressible turbulence with a length scale larger than the particle mean free path. We derive an ensemble-averaged transport equation of energetic charged particles from an extended transport equation that contains the shear acceleration. The ensemble-averaged transport equation describes particle acceleration by incompressible turbulence (turbulent shear acceleration). We find that for Kolmogorov turbulence, the turbulent shear acceleration becomes important on small scales. Moreover, using Monte Carlo simulations, we confirm that the ensemble-averaged transport equation describes the turbulent shear acceleration.

  14. Maintaining consistency in distributed systems

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.

    1991-01-01

    In systems designed as assemblies of independently developed components, concurrent access to data or data structures normally arises within individual programs, and is controlled using mutual exclusion constructs, such as semaphores and monitors. Where data is persistent and/or sets of operation are related to one another, transactions or linearizability may be more appropriate. Systems that incorporate cooperative styles of distributed execution often replicate or distribute data within groups of components. In these cases, group oriented consistency properties must be maintained, and tools based on the virtual synchrony execution model greatly simplify the task confronting an application developer. All three styles of distributed computing are likely to be seen in future systems - often, within the same application. This leads us to propose an integrated approach that permits applications that use virtual synchrony with concurrent objects that respect a linearizability constraint, and vice versa. Transactional subsystems are treated as a special case of linearizability.

  15. Commnity Petascale Project for Accelerator Science and Simulation: Advancing Computational Science for Future Accelerators and Accelerator Technologies

    SciTech Connect

    Spentzouris, Panagiotis; Cary, John; Mcinnes, Lois Curfman; Mori, Warren; Ng, Cho; Ng, Esmond; Ryne, Robert; /LBL, Berkeley

    2008-07-01

    The design and performance optimization of particle accelerators is essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC1 Accelerator Science and Technology project, the SciDAC2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modeling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multi-physics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors.

  16. Community petascale project for accelerator science and simulation : Advancing computational science for future accelerators and accelerator technologies.

    SciTech Connect

    Spentzouris, P.; Cary, J.; McInnes, L. C.; Mori, W.; Ng, C.; Ng, E.; Ryne, R.

    2008-01-01

    The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R & D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors.

  17. Commnity Petascale Project for Accelerator Science And Simulation: Advancing Computational Science for Future Accelerators And Accelerator Technologies

    SciTech Connect

    Spentzouris, Panagiotis; Cary, John; Mcinnes, Lois Curfman; Mori, Warren; Ng, Cho; Ng, Esmond; Ryne, Robert; /LBL, Berkeley

    2011-10-21

    The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors.

  18. Accelerating Particles with Plasma

    SciTech Connect

    Litos, Michael; Hogan, Mark

    2014-11-05

    Researchers at SLAC explain how they use plasma wakefields to accelerate bunches of electrons to very high energies over only a short distance. Their experiments offer a possible path for the future of particle accelerators.

  19. Accelerator Technology Division

    NASA Astrophysics Data System (ADS)

    1992-04-01

    In fiscal year (FY) 1991, the Accelerator Technology (AT) division continued fulfilling its mission to pursue accelerator science and technology and to develop new accelerator concepts for application to research, defense, energy, industry, and other areas of national interest. This report discusses the following programs: The Ground Test Accelerator Program; APLE Free-Electron Laser Program; Accelerator Transmutation of Waste; JAERI, OMEGA Project, and Intense Neutron Source for Materials Testing; Advanced Free-Electron Laser Initiative; Superconducting Super Collider; The High-Power Microwave Program; (Phi) Factory Collaboration; Neutral Particle Beam Power System Highlights; Accelerator Physics and Special Projects; Magnetic Optics and Beam Diagnostics; Accelerator Design and Engineering; Radio-Frequency Technology; Free-Electron Laser Technology; Accelerator Controls and Automation; Very High-Power Microwave Sources and Effects; and GTA Installation, Commissioning, and Operations.

  20. Linear accelerator: A concept

    NASA Technical Reports Server (NTRS)

    Mutzberg, J.

    1972-01-01

    Design is proposed for inexpensive accelerometer which would work by applying pressure to fluid during acceleration. Pressure is used to move shuttle, and shuttle movement is sensed and calibrated to give acceleration readings.

  1. Improved plasma accelerator

    NASA Technical Reports Server (NTRS)

    Cheng, D. Y.

    1971-01-01

    Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

  2. MEQALAC rf accelerating structure

    SciTech Connect

    Keane, J.; Brodowski, J.

    1981-01-01

    A prototype MEQALAC capable of replacing the Cockcroft Walton pre-injector at BNL is being fabricated. Ten milliamperes of H/sup -/ beam supplied from a source sitting at a potential of -40 kilovolt is to be accelerated to 750 keV. This energy gain is provided by a 200 Megahertz accelerating system rather than the normal dc acceleration. Substantial size and cost reduction would be realized by such a system over conventional pre-accelerator systems.

  3. Acceleration gradient of a plasma wakefield accelerator

    SciTech Connect

    Uhm, Han S.

    2008-02-25

    The phase velocity of the wakefield waves is identical to the electron beam velocity. A theoretical analysis indicates that the acceleration gradient of the wakefield accelerator normalized by the wave breaking amplitude is K{sub 0}({xi})/K{sub 1}({xi}), where K{sub 0}({xi}) and K{sub 1}({xi}) are the modified Bessel functions of the second kind of order zero and one, respectively and {xi} is the beam parameter representing the beam intensity. It is also shown that the beam density must be considerably higher than the diffuse plasma density for the large radial velocity of plasma electrons that are required for a high acceleration gradient.

  4. Muon Collider Progress: Accelerators

    SciTech Connect

    Zisman, Michael S.

    2011-09-10

    A muon collider would be a powerful tool for exploring the energy-frontier with leptons, and would complement the studies now under way at the LHC. Such a device would offer several important benefits. Muons, like electrons, are point particles so the full center-of-mass energy is available for particle production. Moreover, on account of their higher mass, muons give rise to very little synchrotron radiation and produce very little beamstrahlung. The first feature permits the use of a circular collider that can make efficient use of the expensive rf system and whose footprint is compatible with an existing laboratory site. The second feature leads to a relatively narrow energy spread at the collision point. Designing an accelerator complex for a muon collider is a challenging task. Firstly, the muons are produced as a tertiary beam, so a high-power proton beam and a target that can withstand it are needed to provide the required luminosity of ~1 × 10{sup 34} cm{sup –2}s{sup –1}. Secondly, the beam is initially produced with a large 6D phase space, which necessitates a scheme for reducing the muon beam emittance (“cooling”). Finally, the muon has a short lifetime so all beam manipulations must be done very rapidly. The Muon Accelerator Program, led by Fermilab and including a number of U.S. national laboratories and universities, has undertaken design and R&D activities aimed toward the eventual construction of a muon collider. Design features of such a facility and the supporting R&D program are described.

  5. Acceleration: It's Elementary

    ERIC Educational Resources Information Center

    Willis, Mariam

    2012-01-01

    Acceleration is one tool for providing high-ability students the opportunity to learn something new every day. Some people talk about acceleration as taking a student out of step. In actuality, what one is doing is putting a student in step with the right curriculum. Whole-grade acceleration, also called grade-skipping, usually happens between…

  6. Far field acceleration

    SciTech Connect

    Fernow, R.C.

    1995-07-01

    Far fields are propagating electromagnetic waves far from their source, boundary surfaces, and free charges. The general principles governing the acceleration of charged particles by far fields are reviewed. A survey of proposed field configurations is given. The two most important schemes, Inverse Cerenkov acceleration and Inverse free electron laser acceleration, are discussed in detail.

  7. Angular Acceleration without Torque?

    ERIC Educational Resources Information Center

    Kaufman, Richard D.

    2012-01-01

    Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.

  8. Particle Acceleration at Oblique CME-driven Shock Using Improved PATH Model

    NASA Astrophysics Data System (ADS)

    Hu, J.; Li, G.; Parker, L. N.; Zank, G. P.

    2015-12-01

    .Gradual solar energetic particle (SEP) events are generally accepted to be caused by particle acceleration at coronal mass ejection(CME)-driven shocks. In this work we improved the PATH(Particle Acceleration and Transport in the Heliosphere) model by initiating a 2D CME-driven shock to investigate particle acceleration at different locations of an oblique CME-drive shock, where the shock has different obliquity angle(θBN). Thus we can study problems like whether quasi-perpendicular or quasi-parallel shock is more efficient in particle acceleration.The PATH model is based on the diffusive shock acceleration mechanism. The core of the model consists of a 3D Zeus module, which computes numerically the background solar wind and the CME-drive shock as inputs; and a shell module where the convection and diffusion of accelerated particles within the shock complex are followed. The 2D CME-driven shock is generated by perturbing the boundary condition of a steady background solar wind in certain patterns.

  9. 3-D RPIC Simulations of Relativistic Jets: Particle Acceleration, Magnetic Field Generation, and Emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Hededal, C. B.; Fishman, G. J.

    2006-01-01

    Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets into ambient plasmas show that acceleration occurs in relativistic shocks. The Weibel instability created in shocks is responsible for particle acceleration, and generation and amplification of highly inhomogeneous, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection in relativistic jets. The "jitter" radiation from deflected electrons has different properties than the synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understand the complex time evolution and spectral structure in relativistic jets and gamma-ray bursts. We will present recent PIC simulations which show particle acceleration and magnetic field generation. We will also calculate associated self-consistent emission from relativistic shocks.

  10. The hardware accelerator array for logic simulation

    SciTech Connect

    Hansen, N H

    1991-05-01

    Hardware acceleration exploits the parallelism inherent in large circuit simulations to achieve significant increases in performance. Simulation accelerators have been developed based on the compiled code algorithm or the event-driven algorithm. The greater flexibility of the event-driven algorithm has resulted in several important developments in hardware acceleration architecture. Some popular commercial products have been developed based on the event-driven algorithm and data-flow architectures. Conventional data-flow architectures require complex switching networks to distribute operands among processing elements resulting in considerable overhead. An accelerator array architecture based on a nearest-neighbor communication has been developed in this thesis. The design is simulated in detail at the behavioral level. Its performance is evaluated and shown to be superior to that of a conventional data-flow accelerator. 14 refs., 48 figs., 5 tabs.

  11. Compact Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2004-01-01

    A plasma accelerator has been conceived for both material-processing and spacecraft-propulsion applications. This accelerator generates and accelerates ions within a very small volume. Because of its compactness, this accelerator could be nearly ideal for primary or station-keeping propulsion for spacecraft having masses between 1 and 20 kg. Because this accelerator is designed to generate beams of ions having energies between 50 and 200 eV, it could also be used for surface modification or activation of thin films.

  12. Accelerating, hyperaccelerating, and decelerating networks

    NASA Astrophysics Data System (ADS)

    Gagen, M. J.; Mattick, J. S.

    2005-07-01

    Many growing networks possess accelerating statistics where the number of links added with each new node is an increasing function of network size so the total number of links increases faster than linearly with network size. In particular, biological networks can display a quadratic growth in regulator number with genome size even while remaining sparsely connected. These features are mutually incompatible in standard treatments of network theory which typically require that every new network node possesses at least one connection. To model sparsely connected networks, we generalize existing approaches and add each new node with a probabilistic number of links to generate either accelerating, hyperaccelerating, or even decelerating network statistics in different regimes. Under preferential attachment for example, slowly accelerating networks display stationary scale-free statistics relatively independent of network size while more rapidly accelerating networks display a transition from scale-free to exponential statistics with network growth. Such transitions explain, for instance, the evolutionary record of single-celled organisms which display strict size and complexity limits.

  13. High brightness electron accelerator

    DOEpatents

    Sheffield, Richard L.; Carlsten, Bruce E.; Young, Lloyd M.

    1994-01-01

    A compact high brightness linear accelerator is provided for use, e.g., in a free electron laser. The accelerator has a first plurality of acclerating cavities having end walls with four coupling slots for accelerating electrons to high velocities in the absence of quadrupole fields. A second plurality of cavities receives the high velocity electrons for further acceleration, where each of the second cavities has end walls with two coupling slots for acceleration in the absence of dipole fields. The accelerator also includes a first cavity with an extended length to provide for phase matching the electron beam along the accelerating cavities. A solenoid is provided about the photocathode that emits the electons, where the solenoid is configured to provide a substantially uniform magnetic field over the photocathode surface to minimize emittance of the electons as the electrons enter the first cavity.

  14. 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.

  15. Pulsed Inductive Plasma Acceleration: Performance Optimization Criteria

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.

    2014-01-01

    Optimization criteria for pulsed inductive plasma acceleration are developed using an acceleration model consisting of a set of coupled circuit equations describing the time-varying current in the thruster and a one-dimensional momentum equation. The model is nondimensionalized, resulting in the identification of several scaling parameters that are varied to optimize the performance of the thruster. The analysis reveals the benefits of underdamped current waveforms and leads to a performance optimization criterion that requires the matching of the natural period of the discharge and the acceleration timescale imposed by the inertia of the working gas. In addition, the performance increases when a greater fraction of the propellant is initially located nearer to the inductive acceleration coil. While the dimensionless model uses a constant temperature formulation in calculating performance, the scaling parameters that yield the optimum performance are shown to be relatively invariant if a self-consistent description of energy in the plasma is instead used.

  16. Acceleration in astrophysics

    SciTech Connect

    Colgate, S.A.

    1993-12-31

    The origin of cosmic rays and applicable laboratory experiments are discussed. Some of the problems of shock acceleration for the production of cosmic rays are discussed in the context of astrophysical conditions. These are: The presumed unique explanation of the power law spectrum is shown instead to be a universal property of all lossy accelerators; the extraordinary isotropy of cosmic rays and the limited diffusion distances implied by supernova induced shock acceleration requires a more frequent and space-filling source than supernovae; the near perfect adiabaticity of strong hydromagnetic turbulence necessary for reflecting the accelerated particles each doubling in energy roughly 10{sup 5} to {sup 6} scatterings with negligible energy loss seems most unlikely; the evidence for acceleration due to quasi-parallel heliosphere shocks is weak. There is small evidence for the expected strong hydromagnetic turbulence, and instead, only a small number of particles accelerate after only a few shock traversals; the acceleration of electrons in the same collisionless shock that accelerates ions is difficult to reconcile with the theoretical picture of strong hydromagnetic turbulence that reflects the ions. The hydromagnetic turbulence will appear adiabatic to the electrons at their much higher Larmor frequency and so the electrons should not be scattered incoherently as they must be for acceleration. Therefore the electrons must be accelerated by a different mechanism. This is unsatisfactory, because wherever electrons are accelerated these sites, observed in radio emission, may accelerate ions more favorably. The acceleration is coherent provided the reconnection is coherent, in which case the total flux, as for example of collimated radio sources, predicts single charge accelerated energies much greater than observed.

  17. SuperB Progress Report for Accelerator

    SciTech Connect

    Biagini, M.E.; Boni, R.; Boscolo, M.; Buonomo, B.; Demma, T.; Drago, A.; Esposito, M.; Guiducci, S.; Mazzitelli, G.; Pellegrino, L.; Preger, M.A.; Raimondi, P.; Ricci, R.; Rotundo, U.; Sanelli, C.; Serio, M.; Stella, A.; Tomassini, S.; Zobov, M.; Bertsche, K.; Brachman, A.; /SLAC /Novosibirsk, IYF /INFN, Pisa /Pisa U. /Orsay, LAL /Annecy, LAPP /LPSC, Grenoble /IRFU, SPP, Saclay /DESY /Cockroft Inst. Accel. Sci. Tech. /U. Liverpool /CERN

    2012-02-14

    This report details the progress made in by the SuperB Project in the area of the Collider since the publication of the SuperB Conceptual Design Report in 2007 and the Proceedings of SuperB Workshop VI in Valencia in 2008. With this document we propose a new electron positron colliding beam accelerator to be built in Italy to study flavor physics in the B-meson system at an energy of 10 GeV in the center-of-mass. This facility is called a high luminosity B-factory with a project name 'SuperB'. This project builds on a long history of successful e+e- colliders built around the world, as illustrated in Figure 1.1. The key advances in the design of this accelerator come from recent successes at the DAFNE collider at INFN in Frascati, Italy, at PEP-II at SLAC in California, USA, and at KEKB at KEK in Tsukuba Japan, and from new concepts in beam manipulation at the interaction region (IP) called 'crab waist'. This new collider comprises of two colliding beam rings, one at 4.2 GeV and one at 6.7 GeV, a common interaction region, a new injection system at full beam energies, and one of the two beams longitudinally polarized at the IP. Most of the new accelerator techniques needed for this collider have been achieved at other recently completed accelerators including the new PETRA-3 light source at DESY in Hamburg (Germany) and the upgraded DAFNE collider at the INFN laboratory at Frascati (Italy), or during design studies of CLIC or the International Linear Collider (ILC). The project is to be designed and constructed by a worldwide collaboration of accelerator and engineering staff along with ties to industry. To save significant construction costs, many components from the PEP-II collider at SLAC will be recycled and used in this new accelerator. The interaction region will be designed in collaboration with the particle physics detector to guarantee successful mutual use. The accelerator collaboration will consist of several groups at present universities and national

  18. The IDS-NF Accelerator Study

    SciTech Connect

    Prior, Christopher R.

    2008-02-21

    The paper outlines the plans of the accelerator group under the International Design Study for a Neutrino Factory. The International Scoping Study, completed in 2006, identified a self-consistent accelerator scenario, which will be used as a baseline design for future work. Essential R and D was also listed, suggesting a programme of development leading into the Conceptual Design Report, to be completed by 2012.

  19. Space experiments with particle accelerators: SEPAC

    NASA Technical Reports Server (NTRS)

    Roberts, B.

    1986-01-01

    The SEPAC instruments consist of an electron accelerator, a plasma accelerator, a neutral gas (N2) release device, particle and field diagnostic instruments, and a low light level television system. These instruments are used to accomplish multiple experiments: to study beam-particle interactions and other plasma processes; as probes to investigate magnetospheric processes; and as perturbation devices to study energy coupling mechanisms in the magnetosphere, ionosphere, and upper atmosphere.

  20. Generalized arc consistency for global cardinality constraint

    SciTech Connect

    Regin, J.C.

    1996-12-31

    A global cardinality constraint (gcc) is specified in terms of a set of variables X = (x{sub 1},..., x{sub p}) which take their values in a subset of V = (v{sub 1},...,v{sub d}). It constrains the number of times a value v{sub i} {epsilon} V is assigned to a variable in X to be in an interval [l{sub i}, c{sub i}]. Cardinality constraints have proved very useful in many real-life problems, such as scheduling, timetabling, or resource allocation. A gcc is more general than a constraint of difference, which requires each interval to be. In this paper, we present an efficient way of implementing generalized arc consistency for a gcc. The algorithm we propose is based on a new theorem of flow theory. Its space complexity is O({vert_bar}X{vert_bar} {times} {vert_bar}V{vert_bar}) and its time complexity is O({vert_bar}X{vert_bar}{sup 2} {times} {vert_bar}V{vert_bar}). We also show how this algorithm can efficiently be combined with other filtering techniques.

  1. Dynamically Reconfigurable Systolic Array Accelerator

    NASA Technical Reports Server (NTRS)

    Dasu, Aravind; Barnes, Robert

    2012-01-01

    A polymorphic systolic array framework has been developed that works in conjunction with an embedded microprocessor on a field-programmable gate array (FPGA), which allows for dynamic and complimentary scaling of acceleration levels of two algorithms active concurrently on the FPGA. Use is made of systolic arrays and a hardware-software co-design to obtain an efficient multi-application acceleration system. The flexible and simple framework allows hosting of a broader range of algorithms, and is extendable to more complex applications in the area of aerospace embedded systems. FPGA chips can be responsive to realtime demands for changing applications needs, but only if the electronic fabric can respond fast enough. This systolic array framework allows for rapid partial and dynamic reconfiguration of the chip in response to the real-time needs of scalability, and adaptability of executables.

  2. On the consistent use of constructed observables

    NASA Astrophysics Data System (ADS)

    Trott, Michael

    2015-02-01

    We define "constructed observables" as relating experimental measurements to terms in a Lagrangian while simultaneously making assumptions about possible deviations from the Standard Model (SM), in other Lagrangian terms. Ensuring that the SM effective field theory (EFT) is constrained correctly when using constructed observables requires that their defining conditions are imposed on the EFT in a manner that is consistent with the equations of motion. Failing to do so can result in a "functionally redundant" operator basis (We define the concept of functional redundancy, which is distinct from the usual concept of an operator basis redundancy, in the introduction.) and the wrong expectation as to how experimental quantities are related in the EFT. We illustrate the issues involved considering the S parameter and the off shell triple gauge coupling (TGC) verticies. We show that the relationships between decay and the off shell TGC verticies are subject to these subtleties, and how the connections between these observables vanish in the limit of strong bounds due to LEP. The challenge of using constructed observables to consistently constrain the Standard Model EFT is only expected to grow with future LHC data, as more complex processes are studied.

  3. Engineered and Administrative Safety Systems for the Control of Prompt Radiation Hazards at Accelerator Facilities

    SciTech Connect

    Liu, James C.; Vylet, Vashek; Walker, Lawrence S.; /SLAC

    2007-12-17

    The ANSI N43.1 Standard, currently in revision (ANSI 2007), sets forth the requirements for accelerator facilities to provide adequate protection for the workers, the public and the environment from the hazards of ionizing radiation produced during and from accelerator operations. The Standard also recommends good practices that, when followed, provide a level of radiation protection consistent with those established for the accelerator communities. The N43.1 Standard is suitable for all accelerator facilities (using electron, positron, proton, or ion particle beams) capable of producing radiation, subject to federal or state regulations. The requirements (see word 'shall') and recommended practices (see word 'should') are prescribed in a graded approach that are commensurate with the complexity and hazard levels of the accelerator facility. Chapters 4, 5 and 6 of the N43.1 Standard address specially the Radiation Safety System (RSS), both engineered and administrative systems, to mitigate and control the prompt radiation hazards from accelerator operations. The RSS includes the Access Control System (ACS) and Radiation Control System (RCS). The main requirements and recommendations of the N43.1 Standard regarding the management, technical and operational aspects of the RSS are described and condensed in this report. Clearly some aspects of the RSS policies and practices at different facilities may differ in order to meet the practical needs for field implementation. A previous report (Liu et al. 2001a), which reviews and summarizes the RSS at five North American high-energy accelerator facilities, as well as the RSS references for the 5 labs (Drozdoff 2001; Gallegos 1996; Ipe and Liu 1992; Liu 1999; Liu 2001b; Rokni 1996; TJNAF 1994; Yotam et al. 1991), can be consulted for the actual RSS implementation at various laboratories. A comprehensive report describing the RSS at the Stanford Linear Accelerator Center (SLAC 2006) can also serve as a reference.

  4. Particle Acceleration in Solar Flares and Associated CME Shocks

    NASA Astrophysics Data System (ADS)

    Petrosian, Vahé

    2016-10-01

    Observations relating the characteristics of electrons seen near Earth (solar energetic particles [SEPs]) and those producing flare radiation show that in certain (prompt) events the origin of both populations appears to be the flare site, which shows strong correlation between the number and spectral index of SEP and hard X-ray radiating electrons, but in others (delayed), which are associated with fast coronal mass ejections (CMEs), this relation is complex and SEPs tend to be harder. Prompt event spectral relation disagrees with that expected in thick or thin target models. We show that using a more accurate treatment of the transport of the accelerated electrons to the footpoints and to Earth can account for this discrepancy. Our results are consistent with those found by Chen & Petrosian for two flares using nonparametric inversion methods, according to which we have weak diffusion conditions, and trapping mediated by magnetic field convergence. The weaker correlations and harder spectra of delayed events can come about by reacceleration of electrons in the CME shock environment. We describe under what conditions such a hardening can be achieved. Using this (acceleration at the flare and reacceleration in the CME) scenario, we show that we can describe the similar dichotomy that exists between the so-called impulsive, highly enriched (3He and heavy ions), and softer SEP events and stronger, more gradual SEP events with near-normal ionic abundances and harder spectra. These methods can be used to distinguish the acceleration mechanisms and to constrain their characteristics.

  5. 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.

  6. Wake field accelerators

    SciTech Connect

    Wilson, P.B.

    1986-02-01

    In a wake field accelerator a high current driving bunch injected into a structure or plasma produces intense induced fields, which are in turn used to accelerate a trailing charge or bunch. The basic concepts of wake field acceleration are described. Wake potentials for closed cavities and periodic structures are derived, as are wake potentials on a collinear path with a charge distribution. Cylindrically symmetric structures excited by a beam in the form of a ring are considered. (LEW)

  7. ACCELERATION RESPONSIVE SWITCH

    DOEpatents

    Chabrek, A.F.; Maxwell, R.L.

    1963-07-01

    An acceleration-responsive device with dual channel capabilities whereby a first circuit is actuated upon attainment of a predetermined maximum acceleration level and when the acceleration drops to a predetermined minimum acceleriltion level another circuit is actuated is described. A fluid-damped sensing mass slidably mounted in a relatively frictionless manner on a shaft through the intermediation of a ball bushing and biased by an adjustable compression spring provides inertially operated means for actuating the circuits. (AEC)

  8. Optically pulsed electron accelerator

    DOEpatents

    Fraser, John S.; Sheffield, Richard L.

    1987-01-01

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radio frequency powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  9. Optically pulsed electron accelerator

    DOEpatents

    Fraser, J.S.; Sheffield, R.L.

    1985-05-20

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radiofrequency-powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  10. Solving radiation problems at particle accelerators

    SciTech Connect

    Nikolai V. Mokhov

    2001-12-11

    At high-intensity high-energy particle accelerators, consequences of a beam-induced radiation impact on machine and detector components, people, environment and complex performance can range from negligible to severe. The specifics, general approach and tools used at such machines for radiation analysis are described. In particular, the world leader Fermilab accelerator complex is considered, with its fixed target and collider experiments, as well as new challenging projects such as LHC, VLHC, muon collider and neutrino factory. The emphasis is on mitigation of deleterious beam-induced radiation effects and on the key role of effective computer simulations.

  11. Acceleration of polarized protons in circular accelerators

    SciTech Connect

    Courant, E.D.; Ruth, R.D.

    1980-09-12

    The theory of depolarization in circular accelerators is presented. The spin equation is first expressed in terms of the particle orbit and then converted to the equivalent spinor equation. The spinor equation is then solved for three different situations: (1) a beam on a flat top near a resonance, (2) uniform acceleration through an isolated resonance, and (3) a model of a fast resonance jump. Finally, the depolarization coefficient, epsilon, is calculated in terms of properties of the particle orbit and the results are applied to a calculation of depolarization in the AGS.

  12. Charged particle accelerator grating

    DOEpatents

    Palmer, Robert B.

    1986-01-01

    A readily disposable and replaceable accelerator grating for a relativistic particle accelerator. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams into the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

  13. 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.

  14. Accelerator-based BNCT.

    PubMed

    Kreiner, A J; Baldo, M; Bergueiro, J R; Cartelli, D; Castell, W; Thatar Vento, V; Gomez Asoia, J; Mercuri, D; Padulo, J; Suarez Sandin, J C; Erhardt, J; Kesque, J M; Valda, A A; Debray, M E; Somacal, H R; Igarzabal, M; Minsky, D M; Herrera, M S; Capoulat, M E; Gonzalez, S J; del Grosso, M F; Gagetti, L; Suarez Anzorena, M; Gun, M; Carranza, O

    2014-06-01

    The activity in accelerator development for accelerator-based BNCT (AB-BNCT) both worldwide and in Argentina is described. Projects in Russia, UK, Italy, Japan, Israel, and Argentina to develop AB-BNCT around different types of accelerators are briefly presented. In particular, the present status and recent progress of the Argentine project will be reviewed. The topics will cover: intense ion sources, accelerator tubes, transport of intense beams, beam diagnostics, the (9)Be(d,n) reaction as a possible neutron source, Beam Shaping Assemblies (BSA), a treatment room, and treatment planning in realistic cases.

  15. Accelerator-based BNCT.

    PubMed

    Kreiner, A J; Baldo, M; Bergueiro, J R; Cartelli, D; Castell, W; Thatar Vento, V; Gomez Asoia, J; Mercuri, D; Padulo, J; Suarez Sandin, J C; Erhardt, J; Kesque, J M; Valda, A A; Debray, M E; Somacal, H R; Igarzabal, M; Minsky, D M; Herrera, M S; Capoulat, M E; Gonzalez, S J; del Grosso, M F; Gagetti, L; Suarez Anzorena, M; Gun, M; Carranza, O

    2014-06-01

    The activity in accelerator development for accelerator-based BNCT (AB-BNCT) both worldwide and in Argentina is described. Projects in Russia, UK, Italy, Japan, Israel, and Argentina to develop AB-BNCT around different types of accelerators are briefly presented. In particular, the present status and recent progress of the Argentine project will be reviewed. The topics will cover: intense ion sources, accelerator tubes, transport of intense beams, beam diagnostics, the (9)Be(d,n) reaction as a possible neutron source, Beam Shaping Assemblies (BSA), a treatment room, and treatment planning in realistic cases. PMID:24365468

  16. Charged particle accelerator grating

    DOEpatents

    Palmer, Robert B.

    1986-09-02

    A readily disposable and replaceable accelerator grating for a relativistic particle accelerator. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams into the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

  17. Particle Simulations of a Linear Dielectric Wall Proton Accelerator

    SciTech Connect

    Poole, B R; Blackfield, D T; Nelson, S D

    2007-06-12

    The dielectric wall accelerator (DWA) is a compact induction accelerator structure that incorporates the accelerating mechanism, pulse forming structure, and switch structure into an integrated module. The DWA consists of stacked stripline Blumlein assemblies, which can provide accelerating gradients in excess of 100 MeV/meter. Blumleins are switched sequentially according to a prescribed acceleration schedule to maintain synchronism with the proton bunch as it accelerates. A finite difference time domain code (FDTD) is used to determine the applied acceleration field to the proton bunch. Particle simulations are used to model the injector as well as the accelerator stack to determine the proton bunch energy distribution, both longitudinal and transverse dynamic focusing, and emittance growth associated with various DWA configurations.

  18. Test stands for testing serial XFEL accelerator modules

    NASA Astrophysics Data System (ADS)

    Bozhko, Yury; Anashin, Vadim; Belova, Lyudmila; Boeckmann, Torsten Axel; Kholopov, Michail; Konstantinov, Valeriy; Petersen, Bernd; Pivovarov, Sergey; Pyata, Eugeny; Sellmann, Detlef; Wang, Xilong; Zhirnov, Anatoly; Zolotov, Anatoly

    2012-06-01

    The superconducting accelerator module is the key component of the European X-ray Free Electron Laser (XFEL) project to be built at DESY Hamburg. The XFEL linear accelerator will consist of 100 accelerator modules in order to produce pulsed electron beam with the energy of 17.5 GeV. All accelerator modules have to be tested after the assembly and before being installed in the accelerator tunnel. The tests will take place in the Accelerator Module Test Facility (AMTF) being constructed at DESY. Besides test stands for testing superconducting cavities and magnets constituting the accelerator modules, AMTF will come with three test stands for testing the completed accelerator modules. This paper describes layout of the test stands within the AMTF, cryogenic design of the test stand, design issues of principal components and schedule.

  19. Simulation of Relativistic Shocks and Associated Self-Consistent Radiation

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; Mizuno, Y.; Nordlund, A.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Fishman, G. J.

    2010-01-01

    Recent PIC simulations of relativistic electron-positron (electron-ion) jets injected into a stationary medium show that particle acceleration occurs at shocked regions. Simulations show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields and particle acceleration. These magnetic fields contribute to the electron's transverse deflection behind the shock. The "jitter" radiation from deflected electrons in turbulent magnetic fields has different properties than synchrotron radiation, which is calculated in a uniform magnetic field. This jitter radiation may be important for understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets in general, and supernova remnants. We will present detailed spectra for conditions relevant of various astrophysical sites of shock formation via the Weibel instability. In particular we will discuss the application to GRBs and SNRs.

  20. Prospects and limitations of cyclotron resonance laser acceleration

    SciTech Connect

    Chen, C. )

    1992-07-01

    The cyclotron resonance laser (CRL) accelerator is a novel concept of accelerating continuous charged-particle beams to moderately or highly relativistic energies. This paper discusses prospects and limitations of this concept. In particular, a three-dimensional, self-consistent theory is used to analyze the nonlinear interaction of an electron beam with an intense traveling electromagnetic wave in such an accelerator. The parameter regimes of experimental interest are identified on the basis of scaling calculations. The results of simulation modeling of a multimegavolt electron CRL accelerator are presented. The possibility of building continuous-wave (cw) CRL accelerators is discussed.

  1. Angular velocities, angular accelerations, and coriolis accelerations

    NASA Technical Reports Server (NTRS)

    Graybiel, A.

    1975-01-01

    Weightlessness, rotating environment, and mathematical analysis of Coriolis acceleration is described for man's biological effective force environments. Effects on the vestibular system are summarized, including the end organs, functional neurology, and input-output relations. Ground-based studies in preparation for space missions are examined, including functional tests, provocative tests, adaptive capacity tests, simulation studies, and antimotion sickness.

  2. Accelerators Beyond The Tevatron?

    SciTech Connect

    Lach, Joseph; /Fermilab

    2010-07-01

    Following the successful operation of the Fermilab superconducting accelerator three new higher energy accelerators were planned. They were the UNK in the Soviet Union, the LHC in Europe, and the SSC in the United States. All were expected to start producing physics about 1995. They did not. Why?

  3. Accelerators Beyond The Tevatron?

    SciTech Connect

    Lach, Joseph

    2010-07-29

    Following the successful operation of the Fermilab superconducting accelerator three new higher energy accelerators were planned. They were the UNK in the Soviet Union, the LHC in Europe, and the SSC in the United States. All were expected to start producing physics about 1995. They did not. Why?.

  4. Accelerators (4/5)

    ScienceCinema

    None

    2016-07-12

    1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

  5. Induction linear accelerators

    NASA Astrophysics Data System (ADS)

    Birx, Daniel

    1992-03-01

    Among the family of particle accelerators, the Induction Linear Accelerator is the best suited for the acceleration of high current electron beams. Because the electromagnetic radiation used to accelerate the electron beam is not stored in the cavities but is supplied by transmission lines during the beam pulse it is possible to utilize very low Q (typically<10) structures and very large beam pipes. This combination increases the beam breakup limited maximum currents to of order kiloamperes. The micropulse lengths of these machines are measured in 10's of nanoseconds and duty factors as high as 10-4 have been achieved. Until recently the major problem with these machines has been associated with the pulse power drive. Beam currents of kiloamperes and accelerating potentials of megavolts require peak power drives of gigawatts since no energy is stored in the structure. The marriage of liner accelerator technology and nonlinear magnetic compressors has produced some unique capabilities. It now appears possible to produce electron beams with average currents measured in amperes, peak currents in kiloamperes and gradients exceeding 1 MeV/meter, with power efficiencies approaching 50%. The nonlinear magnetic compression technology has replaced the spark gap drivers used on earlier accelerators with state-of-the-art all-solid-state SCR commutated compression chains. The reliability of these machines is now approaching 1010 shot MTBF. In the following paper we will briefly review the historical development of induction linear accelerators and then discuss the design considerations.

  6. Accelerators (3/5)

    ScienceCinema

    None

    2016-07-12

    1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

  7. Accelerators (5/5)

    ScienceCinema

    None

    2016-07-12

    1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

  8. Accelerators (5/5)

    SciTech Connect

    2009-07-09

    1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

  9. Accelerators (4/5)

    SciTech Connect

    2009-07-08

    1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

  10. Accelerators (3/5)

    SciTech Connect

    2009-07-07

    1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

  11. Ion Induction Accelerators

    NASA Astrophysics Data System (ADS)

    Barnard, John J.; Horioka, Kazuhiko

    The description of beams in RF and induction accelerators share many common features. Likewise, there is considerable commonality between electron induction accelerators (see Chap. 7) and ion induction accelerators. However, in contrast to electron induction accelerators, there are fewer ion induction accelerators that have been operated as application-driven user facilities. Ion induction accelerators are envisioned for applications (see Chap. 10) such as Heavy Ion Fusion (HIF), High Energy Density Physics (HEDP), and spallation neutron sources. Most ion induction accelerators constructed to date have been limited scale facilities built for feasibility studies for HIF and HEDP where a large numbers of ions are required on target in short pulses. Because ions are typically non-relativistic or weakly relativistic in much of the machine, space-charge effects can be of crucial importance. This contrasts the situation with electron machines, which are usually strongly relativistic leading to weaker transverse space-charge effects and simplified longitudinal dynamics. Similarly, the bunch structure of ion induction accelerators relative to RF machines results in significant differences in the longitudinal physics.

  12. Particle Acceleration in Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-Ichi

    2005-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma ray burst (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments.

  13. 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.

  14. Diagnostics for induction accelerators

    SciTech Connect

    Fessenden, T.J.

    1996-04-01

    The induction accelerator was conceived by N. C. Christofilos and first realized as the Astron accelerator that operated at LLNL from the early 1960`s to the end of 1975. This accelerator generated electron beams at energies near 6 MeV with typical currents of 600 Amperes in 400 ns pulses. The Advanced Test Accelerator (ATA) built at Livermore`s Site 300 produced 10,000 Ampere beams with pulse widths of 70 ns at energies approaching 50 MeV. Several other electron and ion induction accelerators have been fabricated at LLNL and LBNL. This paper reviews the principal diagnostics developed through efforts by scientists at both laboratories for measuring the current, position, energy, and emittance of beams generated by these high current, short pulse accelerators. Many of these diagnostics are closely related to those developed for other accelerators. However, the very fast and intense current pulses often require special diagnostic techniques and considerations. The physics and design of the more unique diagnostics developed for electron induction accelerators are presented and discussed in detail.

  15. KEK digital accelerator

    NASA Astrophysics Data System (ADS)

    Iwashita, T.; Adachi, T.; Takayama, K.; Leo, K. W.; Arai, T.; Arakida, Y.; Hashimoto, M.; Kadokura, E.; Kawai, M.; Kawakubo, T.; Kubo, Tomio; Koyama, K.; Nakanishi, H.; Okazaki, K.; Okamura, K.; Someya, H.; Takagi, A.; Tokuchi, A.; Wake, M.

    2011-07-01

    The High Energy Accelerator Research Organization KEK digital accelerator (KEK-DA) is a renovation of the KEK 500 MeV booster proton synchrotron, which was shut down in 2006. The existing 40 MeV drift tube linac and rf cavities have been replaced by an electron cyclotron resonance (ECR) ion source embedded in a 200 kV high-voltage terminal and induction acceleration cells, respectively. A DA is, in principle, capable of accelerating any species of ion in all possible charge states. The KEK-DA is characterized by specific accelerator components such as a permanent magnet X-band ECR ion source, a low-energy transport line, an electrostatic injection kicker, an extraction septum magnet operated in air, combined-function main magnets, and an induction acceleration system. The induction acceleration method, integrating modern pulse power technology and state-of-art digital control, is crucial for the rapid-cycle KEK-DA. The key issues of beam dynamics associated with low-energy injection of heavy ions are beam loss caused by electron capture and stripping as results of the interaction with residual gas molecules and the closed orbit distortion resulting from relatively high remanent fields in the bending magnets. Attractive applications of this accelerator in materials and biological sciences are discussed.

  16. Accelerator neutrino program at Fermilab

    SciTech Connect

    Parke, Stephen J.; /Fermilab

    2010-05-01

    The accelerator neutrino programme in the USA consists primarily of the Fermilab neutrino programme. Currently, Fermilab operates two neutrino beamlines, the Booster neutrino beamline and the NuMI neutrino beamline and is the planning stages for a third neutrino beam to send neutrinos to DUSEL. The experiments in the Booster neutrino beamline are miniBooNE, SciBooNE and in the future microBooNE, whereas in the NuMI beamline we have MINOS, ArgoNut, MINERVA and coming soon NOvA. The major experiment in the beamline to DUSEL will be LBNE.

  17. Controllable Laser Ion Acceleration

    NASA Astrophysics Data System (ADS)

    Kawata, S.; Kamiyama, D.; Ohtake, Y.; Takano, M.; Barada, D.; Kong, Q.; Wang, P. X.; Gu, Y. J.; Wang, W. M.; Limpouch, J.; Andreev, A.; Bulanov, S. V.; Sheng, Z. M.; Klimo, O.; Psikal, J.; Ma, Y. Y.; Li, X. F.; Yu, Q. S.

    2016-02-01

    In this paper a future laser ion accelerator is discussed to make the laser-based ion accelerator compact and controllable. Especially a collimation device is focused in this paper. The future laser ion accelerator should have an ion source, ion collimators, ion beam bunchers, and ion post acceleration devices [Laser Therapy 22, 103(2013)]: the ion particle energy and the ion energy spectrum are controlled to meet requirements for a future compact laser ion accelerator for ion cancer therapy or for other purposes. The energy efficiency from the laser to ions is improved by using a solid target with a fine sub-wavelength structure or a near-critical density gas plasma. The ion beam collimation is performed by holes behind the solid target or a multi-layered solid target. The control of the ion energy spectrum and the ion particle energy, and the ion beam bunching would be successfully realized by a multistage laser-target interaction.

  18. Cascaded radiation pressure acceleration

    SciTech Connect

    Pei, Zhikun; Shen, Baifei E-mail: zhxm@siom.ac.cn; Zhang, Xiaomei E-mail: zhxm@siom.ac.cn; Wang, Wenpeng; Zhang, Lingang; Yi, Longqing; Shi, Yin; Xu, Zhizhan

    2015-07-15

    A cascaded radiation-pressure acceleration scheme is proposed. When an energetic proton beam is injected into an electrostatic field moving at light speed in a foil accelerated by light pressure, protons can be re-accelerated to much higher energy. An initial 3-GeV proton beam can be re-accelerated to 7 GeV while its energy spread is narrowed significantly, indicating a 4-GeV energy gain for one acceleration stage, as shown in one-dimensional simulations and analytical results. The validity of the method is further confirmed by two-dimensional simulations. This scheme provides a way to scale proton energy at the GeV level linearly with laser energy and is promising to obtain proton bunches at tens of gigaelectron-volts.

  19. Measurement of Coriolis Acceleration with a Smartphone

    NASA Astrophysics Data System (ADS)

    Shakur, Asif; Kraft, Jakob

    2016-05-01

    Undergraduate physics laboratories seldom have experiments that measure the Coriolis acceleration. This has traditionally been the case owing to the inherent complexities of making such measurements. Articles on the experimental determination of the Coriolis acceleration are few and far between in the physics literature. However, because modern smartphones come with a raft of built-in sensors, we have a unique opportunity to experimentally determine the Coriolis acceleration conveniently in a pedagogically enlightening environment at modest cost by using student-owned smartphones. Here we employ the gyroscope and accelerometer in a smartphone to verify the dependence of Coriolis acceleration on the angular velocity of a rotatingtrack and the speed of the sliding smartphone.

  20. 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.

  1. GPU-Accelerated Text Mining

    SciTech Connect

    Cui, Xiaohui; Mueller, Frank; Zhang, Yongpeng; Potok, Thomas E

    2009-01-01

    Accelerating hardware devices represent a novel promise for improving the performance for many problem domains but it is not clear for which domains what accelerators are suitable. While there is no room in general-purpose processor design to significantly increase the processor frequency, developers are instead resorting to multi-core chips duplicating conventional computing capabilities on a single die. Yet, accelerators offer more radical designs with a much higher level of parallelism and novel programming environments. This present work assesses the viability of text mining on CUDA. Text mining is one of the key concepts that has become prominent as an effective means to index the Internet, but its applications range beyond this scope and extend to providing document similarity metrics, the subject of this work. We have developed and optimized text search algorithms for GPUs to exploit their potential for massive data processing. We discuss the algorithmic challenges of parallelization for text search problems on GPUs and demonstrate the potential of these devices in experiments by reporting significant speedups. Our study may be one of the first to assess more complex text search problems for suitability for GPU devices, and it may also be one of the first to exploit and report on atomic instruction usage that have recently become available in NVIDIA devices.

  2. Performance of a compact injector for heavy-ion medical accelerators

    NASA Astrophysics Data System (ADS)

    Iwata, Y.; Yamada, S.; Murakami, T.; Fujimoto, T.; Fujisawa, T.; Ogawa, H.; Miyahara, N.; Yamamoto, K.; Hojo, S.; Sakamoto, Y.; Muramatsu, M.; Takeuchi, T.; Mitsumoto, T.; Tsutsui, H.; Watanabe, T.; Ueda, T.

    2007-03-01

    A compact injector, designed for a heavy-ion medical accelerator complex, was constructed. It consists of an Electron-Cyclotron-Resonance Ion-Source (ECRIS) and two linacs, which are a Radio-Frequency-Quadrupole linac and an Interdigital H-mode Drift-Tube-Linac (IH-DTL) having the same operating frequency of 200 MHz. For beam focusing of the IH-DTL, the method of Alternating-Phase-Focusing (APF) was employed. The compact injector can accelerate heavy ions having a charge-to-mass ratio of {q}/{m}={1}/{3} up to 4.0 MeV/u. Use of the APF IH-DTL and operating frequency of 200 MHz allowed us to design compact linacs; the total length of the two linacs is less than 6 m. Beam-acceleration tests of the compact injector system were performed. The measured intensity of accelerated C4+12 beams with the compact injector was 380 eμA. Beam transmission of the APF IH-DTL was estimated to be as high as 96%, which is comparable to the value calculated by a simulation code. Transverse phase-space and energy distributions of accelerated beams were measured and compared with those calculated by the simulation code, and we found that they were agreed well with each other.

  3. Short communication: a system for remote monitoring of a hospital linear accelerator.

    PubMed

    Jennings, C S

    1996-05-01

    Linear accelerators are complex machines with many parameters affecting the quality of the treatment beam delivered. A high level of technical support is required but this can be difficult to achieve if the linear accelerator is at a centre distant from a medical physics department. This paper describes a solution to this problem whereby a newly installed linear accelerator at the Royal Shrewsbury Hospital is remotely monitored from the Royal Hospital, Wolverhampton. The system enables run-up procedures to be completed by guiding radiographers at Shrewsbury through a series of steps. It consists of electronic hardware connected to the linear accelerator, under the control of a computer. The machine parameters are read and tested against preset tolerances. The monitoring system has been installed and is in routine use. The benefits have been shown to be: a saving in staff time and travel costs, the satisfactory completion of run-up procedures, a higher level of efficiency in the medical physics service provided and effective quality control. Finally, some future developments are presented. These include the development of a real time remote monitoring system that constantly monitors the linear accelerator, allowing the Medical Physics Department access to the machine parameters at any time.

  4. ACE3P Computations of Wakefield Coupling in the CLIC Two-Beam Accelerator

    SciTech Connect

    Candel, Arno; Li, Z.; Ng, C.; Rawat, V.; Schussman, G.; Ko, K.; Syratchev, I.; Grudiev, A.; Wuensch, W.; /CERN

    2010-10-27

    The Compact Linear Collider (CLIC) provides a path to a multi-TeV accelerator to explore the energy frontier of High Energy Physics. Its novel two-beam accelerator concept envisions rf power transfer to the accelerating structures from a separate high-current decelerator beam line consisting of power extraction and transfer structures (PETS). It is critical to numerically verify the fundamental and higher-order mode properties in and between the two beam lines with high accuracy and confidence. To solve these large-scale problems, SLAC's parallel finite element electromagnetic code suite ACE3P is employed. Using curvilinear conformal meshes and higher-order finite element vector basis functions, unprecedented accuracy and computational efficiency are achieved, enabling high-fidelity modeling of complex detuned structures such as the CLIC TD24 accelerating structure. In this paper, time-domain simulations of wakefield coupling effects in the combined system of PETS and the TD24 structures are presented. The results will help to identify potential issues and provide new insights on the design, leading to further improvements on the novel CLIC two-beam accelerator scheme.

  5. Diagnosing particle acceleration in relativistic jets

    NASA Astrophysics Data System (ADS)

    Böttcher, Markus; Baring, Matthew G.; Liang, Edison P.; Summerlin, Errol J.; Fu, Wen; Smith, Ian A.; Roustazadeh, Parisa

    2015-03-01

    The high-energy emission from blazars and other relativistic jet sources indicates that electrons are accelerated to ultra-relativistic (GeV - TeV) energies in these systems. This paper summarizes recent results from numerical studies of two fundamentally different particle acceleration mechanisms potentially at work in relativistic jets: Magnetic-field generation and relativistic particle acceleration in relativistic shear layers, which are likely to be present in relativistic jets, is studied via Particle-in-Cell (PIC) simulations. Diffusive shock acceleration at relativistic shocks is investigated using Monte-Carlo simulations. The resulting magnetic-field configurations and thermal + non-thermal particle distributions are then used to predict multi-wavelength radiative (synchrotron + Compton) signatures of both acceleration scenarios. In particular, we address how anisotropic shear-layer acceleration may be able to circumvent the well-known Lorentz-factor crisis, and how the self-consistent evaluation of thermal + non-thermal particle populations in diffusive shock acceleration simulations provides tests of the bulk Comptonization model for the Big Blue Bump observed in the SEDs of several blazars.

  6. Accelerated glass reaction under PCT conditions

    SciTech Connect

    Ebert, W.L.; Bates, J.K.; Buck, E.C.; Bradley, C.R.

    1992-01-01

    Static leach tests similar to PCT (Product Consistency Test) were performed for up to 2 years to assess long-term reaction behavior of high-level nuclear waste glasses similar to those at Defense Waste Processing Facility. These tests show the reaction rate to decrease with the reaction time from an initially high rate to a low rate, but then to accelerate to a higher rate after reaction times of about 1 year, depending on glass surface area/leachant volume ratio used. Solution concentrations of soluble glass components increase as the reaction is accelerated, while release of other glass components into solution is controlled by secondary phases. Net result is that transformation of glass to stable phases is accelerated while the solution becomes enriched in soluble components not effectively contained in secondary phases. Rate becomes linear in time after the acceleration and may be similar to the initial forward rate. A current model of glass reaction predicts that the glass reaction will be accelerated upon the formation of secondary phases which lower the silicic acid solution concentration. These tests show total Si concentration to increase upon reaction acceleration, however, which may be due to the slightly higher pH attained with the acceleration. The sudden change in the reaction rate is likely due to secondary phase formation. 17 refs, 2 tabs, 3 figs.

  7. Accelerated glass reaction under PCT conditions

    SciTech Connect

    Ebert, W.L.; Bates, J.K.; Buck, E.C.; Bradley, C.R.

    1992-12-31

    Static leach tests similar to PCT (Product Consistency Test) were performed for up to 2 years to assess long-term reaction behavior of high-level nuclear waste glasses similar to those at Defense Waste Processing Facility. These tests show the reaction rate to decrease with the reaction time from an initially high rate to a low rate, but then to accelerate to a higher rate after reaction times of about 1 year, depending on glass surface area/leachant volume ratio used. Solution concentrations of soluble glass components increase as the reaction is accelerated, while release of other glass components into solution is controlled by secondary phases. Net result is that transformation of glass to stable phases is accelerated while the solution becomes enriched in soluble components not effectively contained in secondary phases. Rate becomes linear in time after the acceleration and may be similar to the initial forward rate. A current model of glass reaction predicts that the glass reaction will be accelerated upon the formation of secondary phases which lower the silicic acid solution concentration. These tests show total Si concentration to increase upon reaction acceleration, however, which may be due to the slightly higher pH attained with the acceleration. The sudden change in the reaction rate is likely due to secondary phase formation. 17 refs, 2 tabs, 3 figs.

  8. Acceleration of black hole universe

    NASA Astrophysics Data System (ADS)

    Zhang, T. X.; Frederick, C.

    2014-01-01

    Recently, Zhang slightly modified the standard big bang theory and developed a new cosmological model called black hole universe, which is consistent with Mach's principle, governed by Einstein's general theory of relativity, and able to explain all observations of the universe. Previous studies accounted for the origin, structure, evolution, expansion, and cosmic microwave background radiation of the black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present state with hundred billion-trillions of solar masses by accreting ambient matter and merging with other black holes. This paper investigates acceleration of the black hole universe and provides an alternative explanation for the redshift and luminosity distance measurements of type Ia supernovae. The results indicate that the black hole universe accelerates its expansion when it accretes the ambient matter in an increasing rate. In other words, i.e., when the second-order derivative of the mass of the black hole universe with respect to the time is positive . For a constant deceleration parameter , we can perfectly explain the type Ia supernova measurements with the reduced chi-square to be very close to unity, χ red˜1.0012. The expansion and acceleration of black hole universe are driven by external energy.

  9. Acceleration of Ions and Electrons by Coronal Shocks

    NASA Astrophysics Data System (ADS)

    Sandroos, A.

    2013-12-01

    Diffusive shock acceleration (DSA) of particles at collisionless shock waves driven by coronal mass ejections (CMEs) is the best developed theory for the genesis of gradual solar energetic particle (SEP) events. According to DSA, particles scatter from fluctuations present in the ambient magnetic field, which causes some particles to encounter the shock front repeatedly and to gain energy during each crossing. DSA operating in solar corona is a complex process whose outcome depends on multiple parameters such as shock speed and strength, magnetic geometry, and composition of seed particles. Currently, STEREO and other near-Earth spacecraft are providing valuable multi-point information on how SEP properties, such as composition and energy spectra, vary in longitude. Initial results have shown that longitude distributions of large CME-associated SEP events are much wider than previously thought. These findings have many important consequences on SEP modeling. For example, it is important to extend the present models into two or three spatial coordinates to properly account for the effects of coronal and interplanetary magnetic geometry and the evolution of the CME-driven shock wave on the acceleration and transport of SEPs. We present a new model for the shock acceleration of ions and electrons in the solar corona and discuss implications for particle properties (energy spectra, longitudinal distribution, composition) in the resulting gradual SEP events. We also discuss the possible emission of type II radio waves by the accelerated coronal electrons. In the new model, the ion pitch angle scattering rate is calculated from modeled Alfvén wave power spectra using quasilinear theory. The energy gained by ions in scatterings are self-consistently removed from waves so that total energy (ions+waves) is conserved. New model has been implemented on massively parallel simulation platform Corsair.

  10. Accelerated testing of space mechanisms

    NASA Technical Reports Server (NTRS)

    Murray, S. Frank; Heshmat, Hooshang

    1995-01-01

    This report contains a review of various existing life prediction techniques used for a wide range of space mechanisms. Life prediction techniques utilized in other non-space fields such as turbine engine design are also reviewed for applicability to many space mechanism issues. The development of new concepts on how various tribological processes are involved in the life of the complex mechanisms used for space applications are examined. A 'roadmap' for the complete implementation of a tribological prediction approach for complex mechanical systems including standard procedures for test planning, analytical models for life prediction and experimental verification of the life prediction and accelerated testing techniques are discussed. A plan is presented to demonstrate a method for predicting the life and/or performance of a selected space mechanism mechanical component.

  11. Operation of the accelerator

    SciTech Connect

    Pardo, R.C.; Batzka, B.; Billquist, P.J.

    1995-08-01

    Fiscal Year 1994 was the first year of seven-day operation since ATLAS became a national user facility in 1985. ATLAS made the most of the opportunity this year by providing 5200 hours of beam on-target to the research program. A record number of 60 experiments were completed and the {open_quotes}facility reliability{close_quotes} remained near the 90% level. Seven-day operation was made possible with the addition to the staff of two operator positions providing single-operator coverage during the weekend period. The normally scheduled coverage was augmented by an on-call list of system experts who respond to emergencies with phone-in advice and return to the Laboratory when necessary. This staffing approach continues but we rearranged our staffing patterns so that we now have one cryogenics engineer working a shift pattern which includes 8-hour daily coverage during the weekend. ATLAS provided a beam mix to users consisting of 26 different isotopic species, 23% of which were for A>100 in FY 1994. Approximately 60% of the beam time was provided by the Positive Ion Injector, slightly less than the usage rate of FY 1993. Experiments using uranium or lead beams accounted for 16.4% of the total beam time. The ECR ion source and high-voltage platform functioned well throughout the year. A new technique for solid material production in the source was developed which uses a sputtering process wherein the sample of material placed near the plasma chamber wall is biased negatively. Plasma ions are accelerated into the sample and material is sputtered from the surface into the plasma. This technique is now used routinely for many elements. Runs of calcium, germanium, nickel, lead, tellurium, and uranium were carried out with this technique.

  12. Large electrostatic accelerators

    SciTech Connect

    Jones, C.M.

    1984-01-01

    The increasing importance of energetic heavy ion beams in the study of atomic physics, nuclear physics, and materials science has partially or wholly motivated the construction of a new generation of large electrostatic accelerators designed to operate at terminal potentials of 20 MV or above. In this paper, the author briefly discusses the status of these new accelerators and also discusses several recent technological advances which may be expected to further improve their performance. The paper is divided into four parts: (1) a discussion of the motivation for the construction of large electrostatic accelerators, (2) a description and discussion of several large electrostatic accelerators which have been recently completed or are under construction, (3) a description of several recent innovations which may be expected to improve the performance of large electrostatic accelerators in the future, and (4) a description of an innovative new large electrostatic accelerator whose construction is scheduled to begin next year. Due to time and space constraints, discussion is restricted to consideration of only tandem accelerators.

  13. Analyzing radial acceleration with a smartphone acceleration sensor

    NASA Astrophysics Data System (ADS)

    Vogt, Patrik; Kuhn, Jochen

    2013-03-01

    This paper continues the sequence of experiments using the acceleration sensor of smartphones (for description of the function and the use of the acceleration sensor, see Ref. 1) within this column, in this case for analyzing the radial acceleration.

  14. The BNL Accelerator Test Facility control system

    SciTech Connect

    Malone, R.; Bottke, I.; Fernow, R.; Ben-Zvi, I.

    1993-01-01

    Described is the VAX/CAMAC-based control system for Brookhaven National Laboratory's Accelerator Test Facility, a laser/linac research complex. Details of hardware and software configurations are presented along with experiences of using Vsystem, a commercial control system package.

  15. Compact RF ion source for industrial electrostatic ion accelerator

    NASA Astrophysics Data System (ADS)

    Kwon, Hyeok-Jung; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub

    2016-02-01

    Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

  16. Compact RF ion source for industrial electrostatic ion accelerator.

    PubMed

    Kwon, Hyeok-Jung; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub

    2016-02-01

    Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

  17. Confronting Twin Paradox Acceleration

    NASA Astrophysics Data System (ADS)

    Murphy, Thomas W.

    2016-05-01

    The resolution to the classic twin paradox in special relativity rests on the asymmetry of acceleration. Yet most students are not exposed to a satisfactory analysis of what exactly happens during the acceleration phase that results in the nonaccelerated observer's more rapid aging. The simple treatment presented here offers both graphical and quantitative solutions to the problem, leading to the correct result that the acceleration-induced age gap is 2Lβ years when the one-way distance L is expressed in light-years and velocity β ≡v/c .

  18. Twisted waveguide accelerating structure.

    SciTech Connect

    Kang, Y. W.

    2000-08-15

    A hollow waveguide with a uniform cross section may be used for accelerating charged particles if the phase velocity of an accelerating mode is equal to or less than the free space speed of light. Regular straight hollow waveguides have phase velocities of propagating electromagnetic waves greater than the free-space speed of light. if the waveguide is twisted, the phase velocities of the waveguide modes become slower. The twisted waveguide structure has been modeled and computer simulated in 3-D electromagnetic solvers to show the slow-wave properties for the accelerating mode.

  19. Ion beam accelerator system

    NASA Technical Reports Server (NTRS)

    Aston, Graeme (Inventor)

    1984-01-01

    A system is described that combines geometrical and electrostatic focusing to provide high ion extraction efficiency and good focusing of an accelerated ion beam. The apparatus includes a pair of curved extraction grids (16, 18) with multiple pairs of aligned holes positioned to direct a group of beamlets (20) along converging paths. The extraction grids are closely spaced and maintained at a moderate potential to efficiently extract beamlets of ions and allow them to combine into a single beam (14). An accelerator electrode device (22) downstream from the extraction grids, is at a much lower potential than the grids to accelerate the combined beam.

  20. Ion beam accelerator system

    NASA Technical Reports Server (NTRS)

    Aston, G. (Inventor)

    1981-01-01

    A system is described that combines geometrical and electrostatic focusing to provide high ion extraction efficiency and good focusing of an accelerated ion beam. The apparatus includes a pair of curved extraction grids with multiple pairs of aligned holes positioned to direct a group of beamlets along converging paths. The extraction grids are closely spaced and maintained at a moderate potential to efficiently extract beamlets of ions and allow them to combine into a single beam. An accelerator electrode device downstream from the extraction grids is at a much lower potential than the grids to accelerate the combined beam. The application of the system to ion implantation is mentioned.

  1. [Psychometric properties of a scale: internal consistency].

    PubMed

    Campo-Arias, Adalberto; Oviedo, Heidi C

    2008-01-01

    Internal consistency reliability is the degree of correlation between a scale's items. Internal consistency is calculated by Kuder-Richardson's formula 20 for dichotomous choices and Cronbach's alpha for polytomous items. 0.70 to 0.90 internal consistency is acceptable. 5-25 participants are needed for each item when computing the internal consistency of a twenty-item scale. Internal consistency varies according to population and then it is necessary to report it always that scale is used. PMID:19360231

  2. Argonne Tandem-Linac Accelerator System

    SciTech Connect

    Bollinger, L.M.

    1983-01-01

    Design considerations and operational experience for the existing heavy-ion accelerator consisting of a tandem injecting into a superconducting linac are summarized, with emphasis on the general features of the system. This introduction provides the basis for a discussion of the objectives and design of ATLAS, a larger tandem-linac system being formed by expanding the existing superconducting linac.

  3. Accelerator on a Chip

    ScienceCinema

    England, Joel

    2016-07-12

    SLAC's Joel England explains how the same fabrication techniques used for silicon computer microchips allowed their team to create the new laser-driven particle accelerator chips. (SLAC Multimedia Communications)

  4. Charged particle accelerator grating

    DOEpatents

    Palmer, R.B.

    1985-09-09

    A readily disposable and replaceable accelerator grating for a relativistic particle accelerator is described. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams onto the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

  5. Non-accelerator experiments

    SciTech Connect

    Goldhaber, M.

    1986-01-01

    This report discusses several topics which can be investigated without the use of accelerators. Topics covered are: (1) proton decay, (2) atmospheric neutrinos, (3) neutrino detection, (4) muons from Cygnus X-3, and (5) the double-beta decay.

  6. CLASHING BEAM PARTICLE ACCELERATOR

    DOEpatents

    Burleigh, R.J.

    1961-04-11

    A charged-particle accelerator of the proton synchrotron class having means for simultaneously accelerating two separate contra-rotating particle beams within a single annular magnet structure is reported. The magnet provides two concentric circular field regions of opposite magnetic polarity with one field region being of slightly less diameter than the other. The accelerator includes a deflector means straddling the two particle orbits and acting to collide the two particle beams after each has been accelerated to a desired energy. The deflector has the further property of returning particles which do not undergo collision to the regular orbits whereby the particles recirculate with the possibility of colliding upon subsequent passages through the deflector.

  7. Rare Isotope Accelerators

    NASA Astrophysics Data System (ADS)

    Savard, Guy

    2002-04-01

    The next frontier for low-energy nuclear physics involves experimentation with accelerated beams of short-lived radioactive isotopes. A new facility, the Rare Isotope Accelerator (RIA), is proposed to produce large amount of these rare isotopes and post-accelerate them to energies relevant for studies in nuclear physics, astrophysics and the study of fundamental interactions at low energy. The basic science motivation for this facility will be introduced. The general facility layout, from the 400 kW heavy-ion superconducting linac used for production of the required isotopes to the novel production and extraction schemes and the highly efficient post-accelerator, will be presented. Special emphasis will be put on a number of technical breakthroughs and recent R&D results that enable this new facility.

  8. Accelerator on a Chip

    SciTech Connect

    England, Joel

    2014-06-30

    SLAC's Joel England explains how the same fabrication techniques used for silicon computer microchips allowed their team to create the new laser-driven particle accelerator chips. (SLAC Multimedia Communications)

  9. Wake field acceleration experiments

    SciTech Connect

    Simpson, J.D.

    1988-01-01

    Where and how will wake field acceleration devices find use for other than, possibly, accelerators for high energy physics. I don't know that this can be responsibly answered at this time. What I can do is describe some recent results from an ongoing experimental program at Argonne which support the idea that wake field techniques and devices are potentially important for future accelerators. Perhaps this will spawn expanded interest and even new ideas for the use of this new technology. The Argonne program, and in particular the Advanced Accelerator Test Facility (AATF), has been reported in several fairly recent papers and reports. But because this is a substantially new audience for the subject, I will include a brief review of the program and the facility before describing experiments. 10 refs., 7 figs.

  10. Vibration control in accelerators

    SciTech Connect

    Montag, C.

    2011-01-01

    In the vast majority of accelerator applications, ground vibration amplitudes are well below tolerable magnet jitter amplitudes. In these cases, it is necessary and sufficient to design a rigid magnet support structure that does not amplify ground vibration. Since accelerator beam lines are typically installed at an elevation of 1-2m above ground level, special care has to be taken in order to avoid designing a support structure that acts like an inverted pendulum with a low resonance frequency, resulting in untolerable lateral vibration amplitudes of the accelerator components when excited by either ambient ground motion or vibration sources within the accelerator itself, such as cooling water pumps or helium flow in superconducting magnets. In cases where ground motion amplitudes already exceed the required jiter tolerances, for instance in future linear colliders, passive vibration damping or active stabilization may be considered.

  11. Breakthrough: Fermilab Accelerator Technology

    ScienceCinema

    None

    2016-07-12

    There are more than 30,000 particle accelerators in operation around the world. At Fermilab, scientists are collaborating with other laboratories and industry to optimize the manufacturing processes for a new type of powerful accelerator that uses superconducting niobium cavities. Experimenting with unique polishing materials, a Fermilab team has now developed an efficient and environmentally friendly way of creating cavities that can propel particles with more than 30 million volts per meter.

  12. Collective field accelerator

    DOEpatents

    Luce, John S.

    1978-01-01

    A collective field accelerator which operates with a vacuum diode and utilizes a grooved cathode and a dielectric anode that operates with a relativistic electron beam with a .nu./.gamma. of .about. 1, and a plurality of dielectric lenses having an axial magnetic field thereabout to focus the collectively accelerated electrons and ions which are ejected from the anode. The anode and lenses operate as unoptimized r-f cavities which modulate and focus the beam.

  13. Rolamite acceleration sensor

    DOEpatents

    Abbin, Joseph P.; Briner, Clifton F.; Martin, Samuel B.

    1993-01-01

    A rolamite acceleration sensor which has a failsafe feature including a housing, a pair of rollers, a tension band wrapped in an S shaped fashion around the rollers, wherein the band has a force-generation cut out and a failsafe cut out or weak portion. The failsafe cut out or weak portion breaks when the sensor is subjected to an excessive acceleration so that the sensor fails in an open circuit (non-conducting) state permanently.

  14. Microgravity Acceleration Measurement System

    NASA Technical Reports Server (NTRS)

    Foster, William

    2009-01-01

    Microgravity Acceleration Measurement System (MAMS) is an ongoing study of the small forces (vibrations and accelerations) on the ISS that result from the operation of hardware, crew activities, as well as dockings and maneuvering. Results will be used to generalize the types of vibrations affecting vibration-sensitive experiments. Investigators seek to better understand the vibration environment on the space station to enable future research.

  15. Rolamite acceleration sensor

    DOEpatents

    Abbin, J.P.; Briner, C.F.; Martin, S.B.

    1993-12-21

    A rolamite acceleration sensor is described which has a failsafe feature including a housing, a pair of rollers, a tension band wrapped in an S shaped fashion around the rollers, wherein the band has a force-generation cut out and a failsafe cut out or weak portion. The failsafe cut out or weak portion breaks when the sensor is subjected to an excessive acceleration so that the sensor fails in an open circuit (non-conducting) state permanently. 6 figures.

  16. Laser Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Malka, Victor

    The continuing development of powerful laser systems has permitted to extend the interaction of laser beams with matter far into the relativistic domain, and to demonstrate new approaches for producing energetic particle beams. The extremely large electric fields, with amplitudes exceeding the TV/m level, that are produced in plasma medium are of relevance particle acceleration. Since the value of this longitudinal electric field, 10,000 times larger than those produced in conventional radio-frequency cavities, plasma accelerators appear to be very promising for the development of compact accelerators. The incredible progresses in the understanding of laser plasma interaction physic, allows an excellent control of electron injection and acceleration. Thanks to these recent achievements, laser plasma accelerators deliver today high quality beams of energetic radiation and particles. These beams have a number of interesting properties such as shortness, brightness and spatial quality, and could lend themselves to applications in many fields, including medicine, radio-biology, chemistry, physics and material science,security (material inspection), and of course in accelerator science.

  17. Biomedical accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Freeman, Stewart P. H. T.; Vogel, John S.

    1995-05-01

    Ultrasensitive SIMS with accelerator based spectrometers has recently begun to be applied to biomedical problems. Certain very long-lived radioisotopes of very low natural abundances can be used to trace metabolism at environmental dose levels ( [greater-or-equal, slanted] z mol in mg samples). 14C in particular can be employed to label a myriad of compounds. Competing technologies typically require super environmental doses that can perturb the system under investigation, followed by uncertain extrapolation to the low dose regime. 41Ca and 26Al are also used as elemental tracers. Given the sensitivity of the accelerator method, care must be taken to avoid contamination of the mass spectrometer and the apparatus employed in prior sample handling including chemical separation. This infant field comprises the efforts of a dozen accelerator laboratories. The Center for Accelerator Mass Spectrometry has been particularly active. In addition to collaborating with groups further afield, we are researching the kinematics and binding of genotoxins in-house, and we support innovative uses of our capability in the disciplines of chemistry, pharmacology, nutrition and physiology within the University of California. The field can be expected to grow further given the numerous potential applications and the efforts of several groups and companies to integrate more the accelerator technology into biomedical research programs; the development of miniaturized accelerator systems and ion sources capable of interfacing to conventional HPLC and GMC, etc. apparatus for complementary chemical analysis is anticipated for biomedical laboratories.

  18. Accelerators for America's Future

    NASA Astrophysics Data System (ADS)

    Bai, Mei

    2016-03-01

    Particle accelerator, a powerful tool to energize beams of charged particles to a desired speed and energy, has been the working horse for investigating the fundamental structure of matter and fundermental laws of nature. Most known examples are the 2-mile long Stanford Linear Accelerator at SLAC, the high energy proton and anti-proton collider Tevatron at FermiLab, and Large Hadron Collider that is currently under operation at CERN. During the less than a century development of accelerator science and technology that led to a dazzling list of discoveries, particle accelerators have also found various applications beyond particle and nuclear physics research, and become an indispensible part of the economy. Today, one can find a particle accelerator at almost every corner of our lives, ranging from the x-ray machine at the airport security to radiation diagnostic and therapy in hospitals. This presentation will give a brief introduction of the applications of this powerful tool in fundermental research as well as in industry. Challenges in accelerator science and technology will also be briefly presented

  19. Diffusive Shock Acceleration and Reconnection Acceleration Processes

    NASA Astrophysics Data System (ADS)

    Zank, G. P.; Hunana, P.; Mostafavi, P.; Le Roux, J. A.; Li, Gang; Webb, G. M.; Khabarova, O.; Cummings, A.; Stone, E.; Decker, R.

    2015-12-01

    Shock waves, as shown by simulations and observations, can generate high levels of downstream vortical turbulence, including magnetic islands. We consider a combination of diffusive shock acceleration (DSA) and downstream magnetic-island-reconnection-related processes as an energization mechanism for charged particles. Observations of electron and ion distributions downstream of interplanetary shocks and the heliospheric termination shock (HTS) are frequently inconsistent with the predictions of classical DSA. We utilize a recently developed transport theory for charged particles propagating diffusively in a turbulent region filled with contracting and reconnecting plasmoids and small-scale current sheets. Particle energization associated with the anti-reconnection electric field, a consequence of magnetic island merging, and magnetic island contraction, are considered. For the former only, we find that (i) the spectrum is a hard power law in particle speed, and (ii) the downstream solution is constant. For downstream plasmoid contraction only, (i) the accelerated spectrum is a hard power law in particle speed; (ii) the particle intensity for a given energy peaks downstream of the shock, and the distance to the peak location increases with increasing particle energy, and (iii) the particle intensity amplification for a particular particle energy, f(x,c/{c}0)/f(0,c/{c}0), is not 1, as predicted by DSA, but increases with increasing particle energy. The general solution combines both the reconnection-induced electric field and plasmoid contraction. The observed energetic particle intensity profile observed by Voyager 2 downstream of the HTS appears to support a particle acceleration mechanism that combines both DSA and magnetic-island-reconnection-related processes.

  20. Status and Future Developments in Large Accelerator Control Systems

    SciTech Connect

    Karen S. White

    2006-10-31

    Over the years, accelerator control systems have evolved from small hardwired systems to complex computer controlled systems with many types of graphical user interfaces and electronic data processing. Today's control systems often include multiple software layers, hundreds of distributed processors, and hundreds of thousands of lines of code. While it is clear that the next generation of accelerators will require much bigger control systems, they will also need better systems. Advances in technology will be needed to ensure the network bandwidth and CPU power can provide reasonable update rates and support the requisite timing systems. Beyond the scaling problem, next generation systems face additional challenges due to growing cyber security threats and the likelihood that some degree of remote development and operation will be required. With a large number of components, the need for high reliability increases and commercial solutions can play a key role towards this goal. Future control systems will operate more complex machines and need to present a well integrated, interoperable set of tools with a high degree of automation. Consistency of data presentation and exception handling will contribute to efficient operations. From the development perspective, engineers will need to provide integrated data management in the beginning of the project and build adaptive software components around a central data repository. This will make the system maintainable and ensure consistency throughout the inevitable changes during the machine lifetime. Additionally, such a large project will require professional project management and disciplined use of well-defined engineering processes. Distributed project teams will make the use of standards, formal requirements and design and configuration control vital. Success in building the control system of the future may hinge on how well we integrate commercial components and learn from best practices used in other industries.

  1. Accelerated Molecular Dynamics Simulations of Reactive Hydrocarbon Systems

    SciTech Connect

    Stuart, Steven J.

    2014-02-25

    The research activities in this project consisted of four different sub-projects. Three different accelerated dynamics techniques (parallel replica dynamics, hyperdynamics, and temperature-accelerated dynamics) were applied to the modeling of pyrolysis of hydrocarbons. In addition, parallel replica dynamics was applied to modeling of polymerization.

  2. PARTICLE ACCELERATION IN SUPERLUMINAL STRONG WAVES

    SciTech Connect

    Teraki, Yuto; Ito, Hirotaka; Nagataki, Shigehiro

    2015-06-01

    We calculate the electron acceleration in random superluminal strong waves (SLSWs) and radiation from them using numerical methods in the context of the termination shocks of pulsar wind nebulae. We pursue the orbit of electrons by solving the equation of motion in the analytically expressed electromagnetic turbulences. These consist of a primary SLS and isotropically distributed secondary electromagnetic waves. Under the dominance of the secondary waves, all electrons gain nearly equal energy. On the other hand, when the primary wave is dominant, selective acceleration occurs. The phase of the primary wave for electrons moving nearly along the wavevector changes very slowly compared with the oscillation of the wave, which is “phase-locked,” and such electrons are continuously accelerated. This acceleration by SLSWs may play a crucial role in pre-shock acceleration. In general, the radiation from the phase-locked population is different from the synchro-Compton radiation. However, when the amplitude of the secondary waves is not extremely weaker than that of the primary wave, the typical frequency can be estimated from synchro-Compton theory using the secondary waves. The primary wave does not contribute to the radiation because the SLSW accelerates electrons almost linearly. This radiation can be observed as a radio knot at the upstream of the termination shocks of the pulsar wind nebulae without counterparts in higher frequency ranges.

  3. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1989-01-01

    The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass. The goal of the present program is to demonstrate feasibility of the EPA thruster concept through experimental and theoretical investigations of the EPA acceleration mechanism and discharge chamber performance. Experimental investigations will include operating the test bed ion (TBI) engine as an EPA thruster and parametrically varying the thruster geometry and operating conditions to quantify the electrostatic plasma acceleration effect. The theoretical investigations will include the development of a discharge chamber model which describes the relationships between the engine size, plasma properties, and overall performance. For the EPA thruster to be a viable propulsion concept, overall thruster efficiencies approaching 30% with specific impulses approaching 1000 s must be achieved.

  4. Advanced accelerator theory development

    SciTech Connect

    Sampayan, S.E.; Houck, T.L.; Poole, B.; Tishchenko, N.; Vitello, P.A.; Wang, I.

    1998-02-09

    A new accelerator technology, the dielectric wall accelerator (DWA), is potentially an ultra compact accelerator/pulsed power driver. This new accelerator relies on three new components: the ultra-high gradient insulator, the asymmetric Blumlein and low jitter switches. In this report, we focused our attention on the first two components of the DWA system the insulators and the asymmetric Blumlein. First, we sought to develop the necessary design tools to model and scale the behavior of the high gradient insulator. To perform this task we concentrated on modeling the discharge processes (i.e., initiation and creation of the surface discharge). In addition, because these high gradient structures exhibit favorable microwave properties in certain accelerator configurations, we performed experiments and calculations to determine the relevant electromagnetic properties. Second, we performed circuit modeling to understand energy coupling to dynamic loads by the asymmetric Blumlein. Further, we have experimentally observed a non-linear coupling effect in certain asymmetric Blumlein configurations. That is, as these structures are stacked into a complete module, the output voltage does not sum linearly and a lower than expected output voltage results. Although we solved this effect experimentally, we performed calculations to understand this effect more fully to allow better optimization of this DWA pulse-forming line system.

  5. Newton's Laws: A Very Persistent Consistency

    ERIC Educational Resources Information Center

    Viennot, Laurence

    2012-01-01

    This note is a response to a recent paper by McClelland (2011 "Phys. Educ." 46 469-471). The situation of a person who is walking horizontally along the ground is examined, and the statement "The person is accelerated by a net force from the Earth" is considered invalid. A key point in McClelland's analysis is his claim that: "The force…

  6. Arc-driven rail accelerator research

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.

    1987-01-01

    Arc-driven rail accelerator research is analyzed by considering wall ablation and viscous drag in the plasma. Plasma characteristics are evaluated through a simple fluid-mechanical analysis considering only wall ablation. By equating the energy dissipated in the plasma with the radiation heat loss, the average properties of the plasma are determined as a function of time and rate of ablation. Locations of two simultaneously accelerating arcs were determined by optical and magnetic probes and fron streak camera photographs. All three measurements provide consistent results.

  7. Plasma-based accelerator structures

    SciTech Connect

    Schroeder, Carl B.

    1999-12-01

    Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating structure, the generation of ultrashort electron bunches, and the propagation of laser pulses is underdense plasmas.

  8. Perturbations for transient acceleration

    SciTech Connect

    Vargas, Cristofher Zuñiga; Zimdahl, Winfried; Hipólito-Ricaldi, Wiliam S. E-mail: hipolito@ceunes.ufes.br

    2012-04-01

    According to the standard ΛCDM model, the accelerated expansion of the Universe will go on forever. Motivated by recent observational results, we explore the possibility of a finite phase of acceleration which asymptotically approaches another period of decelerated expansion. Extending an earlier study on a corresponding homogeneous and isotropic dynamics, in which interactions between dark matter and dark energy are crucial, the present paper also investigates the dynamics of the matter perturbations both on the Newtonian and General Relativistic (GR) levels and quantifies the potential relevance of perturbations of the dark-energy component. In the background, the model is tested against the Supernova type Ia (SNIa) data of the Constitution set and on the perturbative level against growth rate data, among them those of the WiggleZ survey, and the data of the 2dFGRS project. Our results indicate that a transient phase of accelerated expansion is not excluded by current observations.

  9. Acceleration radioisotope production simulations

    SciTech Connect

    Waters, L.S.; Wilson, W.B.

    1996-12-31

    We have identified 96 radionuclides now being used or under consideration for use in medical applications. Previously, we calculated the production of {sup 99}Mo from enriched and depleted uranium targets at the 800-MeV energy used in the LAMPF accelerator at Los Alamos. We now consider the production of isotopes using lower energy beams, which may become available as a result of new high-intensity spallation target accelerators now being planned. The production of four radionuclides ({sup 7}Be, {sup 67}Cu, {sup 99}Mo, and {sup 195m}Pt) in a simplified proton accelerator target design is being examined. The LAHET, MCNP, and CINDER90 codes were used to model the target, transport a beam of protons and secondary produced particles through the system, and compute the nuclide production from spallation and low-energy neutron interactions. Beam energies of 200 and 400 MeV were used, and several targets were considered for each nuclide.

  10. Laser acceleration with open waveguides

    SciTech Connect

    Xie, Ming

    1999-03-01

    A unified framework based on solid-state open waveguides is developed to overcome all three major limitations on acceleration distance and hence on the feasibility of two classes of laser acceleration. The three limitations are due to laser diffraction, acceleration phase slippage, and damage of waveguide structure by high power laser. The two classes of laser acceleration are direct-field acceleration and ponderomotive-driven acceleration. Thus the solutions provided here encompass all mainstream approaches for laser acceleration, either in vacuum, gases or plasmas.

  11. 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.

  12. Stochastic Particle Acceleration in Impulsive Solar Flares

    NASA Technical Reports Server (NTRS)

    Miller, James A.

    2001-01-01

    The acceleration of a huge number of electrons and ions to relativistic energies over timescales ranging from several seconds to several tens of seconds is the fundamental problem in high-energy solar physics. The cascading turbulence model we have developed has been shown previously (e.g., Miller 2000; Miller & Roberts 1995; Miner, LaRosa, & Moore 1996) to account for all the bulk features (such as acceleration timescales, fluxes, total number of energetic particles, and maximum energies) of electron and proton acceleration in impulsive solar flares. While the simulation of this acceleration process is involved, the essential idea of the model is quite simple, and consists of just a few parts: 1. During the primary flare energy release phase, we assume that low-amplitude MHD Alfven and fast mode waves are excited at long wavelengths, say comparable to the size of the event (although the results are actually insensitive to this initial wavelength). While an assumption, this appears reasonable in light of the likely highly turbulent nature of the flare. 2. These waves then cascade in a Kolmogorov-like fashion to smaller wavelengths (e.g., Verma et al. 1996), forming a power-law spectral density in wavenumber space through the inertial range. 3. When the mean wavenumber of the fast mode waves has increased sufficiently, the transit-time acceleration rate (Miller 1997) for superAlfvenic electrons can overcome Coulomb energy losses, and these electrons are accelerated out of the thermal distribution and to relativistic energies (Miller et al. 1996). As the Alfven waves cascade to higher wavenumbers, they can cyclotron resonate with progressively lower energy protons. Eventually, they will resonate with protons in the tail of the thermal distribution, which will then be accelerated to relativistic energies as well (Miller & Roberts 1995). Hence, both ions and electrons are stochastically accelerated, albeit by different mechanisms and different waves. 4. When the

  13. Accelerated Tank Closure Demonstration Project

    SciTech Connect

    SAMS, T.L.

    2003-02-01

    Among the highest priorities for action under the ''Hanford Federal Facility and Agreement and Consent Order'', hereafter referred to as the Tri-Party Agreement, is the retrieval, treatment and disposal of Hanford Site tank waste. Tank waste is recognized as one of the primary threats to the Columbia River and one of the most complex technical challenges. Progress has been made in resolving safety issues, characterizing tank waste and past tank leaks, enhancing double-shell tank waste transfer and operations systems, retrieving single-shell tank waste, deploying waste treatment facilities, and planning for the disposal of immobilized waste product. However, limited progress has been made in developing technologies and providing a sound technical basis for tank system closure. To address this limitation the Accelerated Tank Closure Demonstration Project was created to develop information through technology demonstrations in support of waste retrieval and closure decisions. To complete its mission the Accelerated Tank Closure Demonstration Project has adopted performance objectives that include: protecting human health and the environment; minimizing/eliminating potential waste releases to the soil and groundwater; preventing water infiltration into the tank; maintaining accessibility of surrounding tanks for future closure; maintaining tank structural integrity; complying with applicable waste retrieval, disposal, and closure regulations; and maintaining flexibility for final closure options in the future.

  14. Diffusive Shock Acceleration

    NASA Astrophysics Data System (ADS)

    Baring, Matthew

    2003-04-01

    The process of diffusive acceleration of charged particles in shocked plasmas is widely invoked in astrophysics to account for the ubiquitous presence of signatures of non-thermal relativistic electrons and ions in the universe. This statistical energization mechanism, manifested in turbulent media, was first posited by Enrico Fermi in 1949 to explain the observed cosmic ray population, which exhibits an almost power-law distribution in rigidity. The absence of a momentum scale is a key characteristic of diffusive shock acceleration, and astrophysical systems generally only impose scales at the injection (low energy) and loss (high energy) ends of the particle spectrum. The existence of structure in the cosmic ray spectrum (the "knee") at around 3000 TeV has promoted contentions that there are at least two origins for cosmic rays, a galactic one supplying those up to the knee, and perhaps an extragalactic one that can explain even the ultra-high energy cosmic rays (UHECRs) seen at 1-300 EeV. Accounting for the UHECRs with familiar astrophysical sites of acceleration has historically proven difficult due to the need to assume high magnetic fields in order to reduce the shortest diffusive acceleration timescale, the ion gyroperiod, to meaningful values. Yet active galaxies and gamma-ray bursts remain strong and interesting candidate sources for UHECRs, turning the theoretical focus to relativistic shocks. This review summarizes properties of diffusive shock acceleration that are salient to the issue of UHECR generation. These include spectral indices, anisotropies, acceleration efficencies and timescales, as functions of the shock speed and mean field orientation, and also the degree of field turbulence. Astrophysical sites for UHECR production are also critiqued.

  15. 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.

  16. HIGH GRADIENT INDUCTION ACCELERATOR

    SciTech Connect

    Caporaso, G J; Sampayan, S; Chen, Y; Blackfield, D; Harris, J; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Nunnally, W; Paul, A; Poole, B; Rhodes, M; Sanders, D; Selenes, K; Sullivan, J; Wang, L; Watson, J

    2007-06-21

    A new type of compact induction accelerator is under development at the Lawrence Livermore National Laboratory that promises to increase the average accelerating gradient by at least an order of magnitude over that of existing induction machines. The machine is based on the use of high gradient vacuum insulators, advanced dielectric materials and switches and is stimulated by the desire for compact flash x-ray radiography sources. Research describing an extreme variant of this technology aimed at proton therapy for cancer will be described. Progress in applying this technology to several applications will be reviewed.

  17. Photocathodes in accelerator applications

    SciTech Connect

    Fraser, J.S.; Sheffield, R.L.; Gray, E.R.; Giles, P.M.; Springer, R.W.; Loebs, V.A.

    1987-01-01

    Some electron accelerator applications require bursts of short pulses at high microscopic repetition rates and high peak brightness. A photocathode, illuminated by a mode-locked laser, is well suited to filling this need. The intrinsic brightness of a photoemitter beam is high; experiments are under way at Los Alamos to study the brightness of short bunches with high space charge after acceleration. A laser-illuminated Cs/sub 3/Sb photoemitter is located in the first rf cavity of an injector linac. Diagnostics include a pepper-pot emittance analyzer, a magnetic spectrometer, and a streak camera.

  18. Interfacing to accelerator instrumentation

    SciTech Connect

    Shea, T.J.

    1995-12-31

    As the sensory system for an accelerator, the beam instrumentation provides a tremendous amount of diagnostic information. Access to this information can vary from periodic spot checks by operators to high bandwidth data acquisition during studies. In this paper, example applications will illustrate the requirements on interfaces between the control system and the instrumentation hardware. A survey of the major accelerator facilities will identify the most popular interface standards. The impact of developments such as isochronous protocols and embedded digital signal processing will also be discussed.

  19. 'Light Sail' Acceleration Reexamined

    SciTech Connect

    Macchi, Andrea; Veghini, Silvia; Pegoraro, Francesco

    2009-08-21

    The dynamics of the acceleration of ultrathin foil targets by the radiation pressure of superintense, circularly polarized laser pulses is investigated by analytical modeling and particle-in-cell simulations. By addressing self-induced transparency and charge separation effects, it is shown that for 'optimal' values of the foil thickness only a thin layer at the rear side is accelerated by radiation pressure. The simple 'light sail' model gives a good estimate of the energy per nucleon, but overestimates the conversion efficiency of laser energy into monoenergetic ions.

  20. Multileaf collimator for Coline medical accelerators

    NASA Astrophysics Data System (ADS)

    Harasimowicz, Janusz; Plebański, Grzegorz; Sajna, Krzysztof

    2008-01-01

    Multileaf collimator (MLC) allows advanced field shaping for radiation therapy delivered with medical accelerators. In this paper theoretical considerations and scientific studies of a new MLC design are described. Considered multileaf collimator model comprises of a multiplicity of tungsten leaves of 1 cm width projected at isocenter plane. To ensure compatibility of a new MLC solution with different accelerator types as well as to assure high reliability in irradiated environment and presence of strong magnetic field, a complex and independent control system had to be developed. It comprises of two modules - one placed in the accelerator treatment head and the other one placed in the control room. Both of them ensure high reliability and treatment quality while working in harsh conditions. Mechanical design and leaf shape optimization algorithm based on a ray tracing method are also described in details. Adapted solutions allowed providing minimized and uniform radiation penumbrae in the full range of leaves positions which is crucial for modern advanced radiotherapy.

  1. Generalized radially self-accelerating helicon beams.

    PubMed

    Vetter, Christian; Eichelkraut, Toni; Ornigotti, Marco; Szameit, Alexander

    2014-10-31

    We report, in theory and experiment, on a new class of optical beams that are radially self-accelerating and nondiffracting. These beams continuously evolve on spiraling trajectories while maintaining their amplitude and phase distribution in their rotating rest frame. We provide a detailed insight into the theoretical origin and characteristics of radial self-acceleration and prove our findings experimentally. As radially self-accelerating beams are nonparaxial and a solution to the full scalar Helmholtz equation, they can be implemented in many linear wave systems beyond optics, from acoustic and elastic waves to surface waves in fluids and soft matter. Our work generalized the study of classical helicon beams to a complete set of solutions for rotating complex fields. PMID:25396370

  2. Electron acceleration in solar flares

    NASA Technical Reports Server (NTRS)

    Droge, Wolfgang; Meyer, Peter; Evenson, Paul; Moses, Dan

    1989-01-01

    For the period Spetember 1978 to December 1982, 55 solar flare particle events for which the instruments on board the ISEE-3 spacecraft detected electrons above 10 MeV. Combining data with those from the ULEWAT spectrometer electron spectra in the range from 0.1 to 100 MeV were obtained. The observed spectral shapes can be divided into two classes. The spectra of the one class can be fit by a single power law in rigidity over the entire observed range. The spectra of the other class deviate from a power law, instead exhibiting a steepening at low rigidities and a flattening at high rigidities. Events with power-law spectra are associated with impulsive (less than 1 hr duration) soft X-ray emission, whereas events with hardening spectra are associated with long-duration (more than 1 hr) soft X-ray emission. The characteristics of long-duration events are consistent with diffusive shock acceleration taking place high in the corona. Electron spectra of short-duration flares are well reproduced by the distribution functions derived from a model assuming simultaneous second-order Fermi acceleration and Coulomb losses operating in closed flare loops.

  3. Probing gravitation, dark energy, and acceleration

    SciTech Connect

    Linder, Eric V.

    2004-02-20

    The acceleration of the expansion of the universe arises from unknown physical processes involving either new fields in high energy physics or modifications of gravitation theory. It is crucial for our understanding to characterize the properties of the dark energy or gravity through cosmological observations and compare and distinguish between them. In fact, close consistencies exist between a dark energy equation of state function w(z) and changes to the framework of the Friedmann cosmological equations as well as direct spacetime geometry quantities involving the acceleration, such as ''geometric dark energy'' from the Ricci scalar. We investigate these interrelationships, including for the case of super acceleration or phantom energy where the fate of the universe may be more gentle than the Big Rip.

  4. Gradient Optimization for SC CW Accelerators

    SciTech Connect

    Schneider, William; Kneisel, Peter; Rode, Claus

    2003-05-01

    The proposed rare isotope accelerator (RIA) design consists of a normally conducting radio frequency quadruple (RFQ) section, a superconducting (SC) drift tube cavity section, a SC elliptical multi-cell cavity section and two charge strippers with associated charge state selection and beam matching optics. The SC elliptical section uses two or three multi-cell beta cavity types installed into cryomodules to span the energy region of about 84.5 MeV/nucleon up to 400 MeV/nucleon. This paper focuses on the gradient optimization of these SC elliptical cavities that provide a significant portion of the total acceleration to the beam. The choice of gradient coupled with the cavity quality factor has a strong affect on the overall cost of the accelerator. The paper describes the optimization of the capital and operating cost associated with the RIA elliptical cavity cryomodules.

  5. Enhancing proton acceleration by using composite targets

    SciTech Connect

    Bulanov, S. S.; Esarey, E.; Schroeder, C. B.; Bulanov, S. V.; Esirkepov, T. Zh.; Kando, M.; Pegoraro, F.; Leemans, W. P.

    2015-07-10

    Efficient laser ion acceleration requires high laser intensities, which can only be obtained by tightly focusing laser radiation. In the radiation pressure acceleration regime, where the tightly focused laser driver leads to the appearance of the fundamental limit for the maximum attainable ion energy, this limit corresponds to the laser pulse group velocity as well as to another limit connected with the transverse expansion of the accelerated foil and consequent onset of the foil transparency. These limits can be relaxed by using composite targets, consisting of a thin foil followed by a near critical density slab. Such targets provide guiding of a laser pulse inside a self-generated channel and background electrons, being snowplowed by the pulse, compensate for the transverse expansion. The use of composite targets results in a significant increase in maximum ion energy, compared to a single foil target case.

  6. Is cosmic acceleration slowing down?

    SciTech Connect

    Shafieloo, Arman; Sahni, Varun; Starobinsky, Alexei A.

    2009-11-15

    We investigate the course of cosmic expansion in its recent past using the Constitution SN Ia sample, along with baryon acoustic oscillations (BAO) and cosmic microwave background (CMB) data. Allowing the equation of state of dark energy (DE) to vary, we find that a coasting model of the universe (q{sub 0}=0) fits the data about as well as Lambda cold dark matter. This effect, which is most clearly seen using the recently introduced Om diagnostic, corresponds to an increase of Om and q at redshifts z < or approx. 0.3. This suggests that cosmic acceleration may have already peaked and that we are currently witnessing its slowing down. The case for evolving DE strengthens if a subsample of the Constitution set consisting of SNLS+ESSENCE+CfA SN Ia data is analyzed in combination with BAO+CMB data. The effect we observe could correspond to DE decaying into dark matter (or something else)

  7. Student Effort, Consistency, and Online Performance

    ERIC Educational Resources Information Center

    Patron, Hilde; Lopez, Salvador

    2011-01-01

    This paper examines how student effort, consistency, motivation, and marginal learning, influence student grades in an online course. We use data from eleven Microeconomics courses taught online for a total of 212 students. Our findings show that consistency, or less time variation, is a statistically significant explanatory variable, whereas…

  8. Does Acquiescence Affect Individual Items Consistently?

    ERIC Educational Resources Information Center

    Kam, Chester Chun Seng; Zhou, Mingming

    2015-01-01

    Previous research has found the effects of acquiescence to be generally consistent across item "aggregates" within a single survey (i.e., essential tau-equivalence), but it is unknown whether this phenomenon is consistent at the" individual item" level. This article evaluated the often assumed but inadequately tested…

  9. 40 CFR 55.12 - Consistency updates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Consistency updates. 55.12 Section 55.12 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) OUTER CONTINENTAL SHELF AIR REGULATIONS § 55.12 Consistency updates. (a) The Administrator will...

  10. Consistent-handed individuals are more authoritarian.

    PubMed

    Lyle, Keith B; Grillo, Michael C

    2014-01-01

    Individuals differ in the consistency with which they use one hand over the other to perform everyday activities. Some individuals are very consistent, habitually using a single hand to perform most tasks. Others are relatively inconsistent, and hence make greater use of both hands. More- versus less-consistent individuals have been shown to differ in numerous aspects of personality and cognition. In several respects consistent-handed individuals resemble authoritarian individuals. For example, both consistent-handedness and authoritarianism have been linked to cognitive inflexibility. Therefore we hypothesised that consistent-handedness is an external marker for authoritarianism. Confirming our hypothesis, we found that consistent-handers scored higher than inconsistent-handers on a measure of submission to authority, were more likely to identify with a conservative political party (Republican), and expressed less-positive attitudes towards out-groups. We propose that authoritarianism may be influenced by the degree of interaction between the left and right brain hemispheres, which has been found to differ between consistent- and inconsistent-handed individuals. PMID:23586369

  11. Consistency and Enhancement Processes in Understanding Emotions

    ERIC Educational Resources Information Center

    Stets, Jan E.; Asencio, Emily K.

    2008-01-01

    Many theories in the sociology of emotions assume that emotions emerge from the cognitive consistency principle. Congruence among cognitions produces good feelings whereas incongruence produces bad feelings. A work situation is simulated in which managers give feedback to workers that is consistent or inconsistent with what the workers expect to…

  12. 24 CFR 91.510 - Consistency determinations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., the proposed activities are consistent with the jurisdiction's strategic plan, and the location of the... of consistency of the application with the approved consolidated plan for the jurisdiction may be... unit of general local government that: is required to have a consolidated plan, is authorized to use...

  13. 24 CFR 91.510 - Consistency determinations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., the proposed activities are consistent with the jurisdiction's strategic plan, and the location of the... of consistency of the application with the approved consolidated plan for the jurisdiction may be... unit of general local government that: is required to have a consolidated plan, is authorized to use...

  14. [Hand Preference: Cognitive Development, Asymmetry, and Consistency.

    ERIC Educational Resources Information Center

    Bathurst, Kay; And Others

    Reported are results of three studies: (1) Hand Preference Consistency during Infancy and Preschool Years (K. Bathurst and A. W. Gottfried), (2) Asymmetry of Verbal Processing: Influence of Family Handedness (K. Bathurst and D. W. Kee), (3) Consistency of Hand Preference and Cognitive Development in Young Children (K. Bathurst and A. W.…

  15. 44 CFR 206.349 - Consistency determinations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... § 206.349 Consistency determinations. Section 6(a)(6) of CBRA requires that certain actions be consistent with the purposes of that statute if the actions are to be carried out on a unit of the CBRA. The... associated with the coastal barriers along with Atlantic and Gulf coasts. For those actions where...

  16. Steps toward Promoting Consistency in Educational Decisions

    ERIC Educational Resources Information Center

    Klein, Joseph

    2010-01-01

    Purpose: The literature indicates the advantages of decisions formulated through intuition, as well as the limitations, such as lack of consistency in similar situations. The principle of consistency (invariance), requiring that two equivalent versions of choice-problems will produce the same preference, is violated in intuitive judgment. This…

  17. Prospects for Accelerator Technology

    NASA Astrophysics Data System (ADS)

    Todd, Alan

    2011-02-01

    Accelerator technology today is a greater than US$5 billion per annum business. Development of higher-performance technology with improved reliability that delivers reduced system size and life cycle cost is expected to significantly increase the total accelerator technology market and open up new application sales. Potential future directions are identified and pitfalls in new market penetration are considered. Both of the present big market segments, medical radiation therapy units and semiconductor ion implanters, are approaching the "maturity" phase of their product cycles, where incremental development rather than paradigm shifts is the norm, but they should continue to dominate commercial sales for some time. It is anticipated that large discovery-science accelerators will continue to provide a specialty market beset by the unpredictable cycles resulting from the scale of the projects themselves, coupled with external political and economic drivers. Although fraught with differing market entry difficulties, the security and environmental markets, together with new, as yet unrealized, industrial material processing applications, are expected to provide the bulk of future commercial accelerator technology growth.

  18. Radioisotope Dating with Accelerators.

    ERIC Educational Resources Information Center

    Muller, Richard A.

    1979-01-01

    Explains a new method of detecting radioactive isotopes by counting their accelerated ions rather than the atoms that decay during the counting period. This method increases the sensitivity by several orders of magnitude, and allows one to find the ages of much older and smaller samples. (GA)

  19. The neutrino electron accelerator

    SciTech Connect

    Shukla, P.K.; Stenflo, L.; Bingham, R.; Bethe, H.A.; Dawson, J.M.; Mendonca, J.T.

    1998-01-01

    It is shown that a wake of electron plasma oscillations can be created by the nonlinear ponderomotive force of an intense neutrino flux. The electrons trapped in the plasma wakefield will be accelerated to high energies. Such processes may be important in supernovas and pulsars. {copyright} {ital 1998 American Institute of Physics.}

  20. FPGA Verification Accelerator (FVAX)

    NASA Technical Reports Server (NTRS)

    Oh, Jane; Burke, Gary

    2008-01-01

    Is Verification Acceleration Possible? - Increasing the visibility of the internal nodes of the FPGA results in much faster debug time - Forcing internal signals directly allows a problem condition to be setup very quickly center dot Is this all? - No, this is part of a comprehensive effort to improve the JPL FPGA design and V&V process.

  1. Pulsed electromagnetic gas acceleration

    NASA Technical Reports Server (NTRS)

    Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

    1974-01-01

    Detailed measurements of the axial velocity profile and electromagnetic structure of a high power, quasi-steady MPD discharge are used to formulate a gasdynamic model of the acceleration process. Conceptually dividing the accelerated plasma into an inner flow and an outer flow, it is found that more than two-thirds of the total power in the plasma is deposited in the inner flow, accelerating it to an exhaust velocity of 12.5 km/sec. The outer flow, which is accelerated to a velocity of only 6.2 km/sec, appears to provide a current conduction path between the inner flow and the anode. Related cathode studies have shown that the critical current for the onset of terminal voltage fluctuations, which was recently shown to be a function of the cathode area, appears to reach an asymptote for cathodes of very large surface area. Detailed floating potential measurements show that the fluctuations are confined to the vicinity of the cathode and hence reflect a cathode emission process rather than a fundamental limit on MPD performance.

  2. Report on accelerated corrosion studies.

    SciTech Connect

    Mowry, Curtis Dale; Glass, Sarah Jill; Sorensen, Neil Robert

    2011-03-01

    Sandia National Laboratories (SNL) conducted accelerated atmospheric corrosion testing for the U.S. Consumer Product Safety Commission (CPSC) to help further the understanding of the development of corrosion products on conductor materials in household electrical components exposed to environmental conditions representative of homes constructed with problem drywall. The conditions of the accelerated testing were chosen to produce corrosion product growth that would be consistent with long-term exposure to environments containing humidity and parts per billion (ppb) levels of hydrogen sulfide (H{sub 2}S) that are thought to have been the source of corrosion in electrical components from affected homes. This report documents the test set-up, monitoring of electrical performance of powered electrical components during the exposure, and the materials characterization conducted on wires, screws, and contact plates from selected electrical components. No degradation in electrical performance (measured via voltage drop) was measured during the course of the 8-week exposure, which was approximately equivalent to 40 years of exposure in a light industrial environment. Analyses show that corrosion products consisting of various phases of copper sulfide, copper sulfate, and copper oxide are found on exposed surfaces of the conductor materials including wires, screws, and contact plates. The morphology and the thickness of the corrosion products showed a range of character. In some of the copper wires that were observed, corrosion product had flaked or spalled off the surface, exposing fresh metal to the reaction with the contaminant gasses; however, there was no significant change in the wire cross-sectional area.

  3. Plasma acceleration above martian magnetic anomalies.

    PubMed

    Lundin, R; Winningham, D; Barabash, S; Frahm, R; Holmström, M; Sauvaud, J-A; Fedorov, A; Asamura, K; Coates, A J; Soobiah, Y; Hsieh, K C; Grande, M; Koskinen, H; Kallio, E; Kozyra, J; Woch, J; Fraenz, M; Brain, D; Luhmann, J; McKenna-Lawler, S; Orsini, R S; Brandt, P; Wurz, P

    2006-02-17

    Auroras are caused by accelerated charged particles precipitating along magnetic field lines into a planetary atmosphere, the auroral brightness being roughly proportional to the precipitating particle energy flux. The Analyzer of Space Plasma and Energetic Atoms experiment on the Mars Express spacecraft has made a detailed study of acceleration processes on the nightside of Mars. We observed accelerated electrons and ions in the deep nightside high-altitude region of Mars that map geographically to interface/cleft regions associated with martian crustal magnetization regions. By integrating electron and ion acceleration energy down to the upper atmosphere, we saw energy fluxes in the range of 1 to 50 milliwatts per square meter per second. These conditions are similar to those producing bright discrete auroras above Earth. Discrete auroras at Mars are therefore expected to be associated with plasma acceleration in diverging magnetic flux tubes above crustal magnetization regions, the auroras being distributed geographically in a complex pattern by the many multipole magnetic field lines extending into space. PMID:16484488

  4. Plasma acceleration above martian magnetic anomalies.

    PubMed

    Lundin, R; Winningham, D; Barabash, S; Frahm, R; Holmström, M; Sauvaud, J-A; Fedorov, A; Asamura, K; Coates, A J; Soobiah, Y; Hsieh, K C; Grande, M; Koskinen, H; Kallio, E; Kozyra, J; Woch, J; Fraenz, M; Brain, D; Luhmann, J; McKenna-Lawler, S; Orsini, R S; Brandt, P; Wurz, P

    2006-02-17

    Auroras are caused by accelerated charged particles precipitating along magnetic field lines into a planetary atmosphere, the auroral brightness being roughly proportional to the precipitating particle energy flux. The Analyzer of Space Plasma and Energetic Atoms experiment on the Mars Express spacecraft has made a detailed study of acceleration processes on the nightside of Mars. We observed accelerated electrons and ions in the deep nightside high-altitude region of Mars that map geographically to interface/cleft regions associated with martian crustal magnetization regions. By integrating electron and ion acceleration energy down to the upper atmosphere, we saw energy fluxes in the range of 1 to 50 milliwatts per square meter per second. These conditions are similar to those producing bright discrete auroras above Earth. Discrete auroras at Mars are therefore expected to be associated with plasma acceleration in diverging magnetic flux tubes above crustal magnetization regions, the auroras being distributed geographically in a complex pattern by the many multipole magnetic field lines extending into space.

  5. Menopause accelerates biological aging.

    PubMed

    Levine, Morgan E; Lu, Ake T; Chen, Brian H; Hernandez, Dena G; Singleton, Andrew B; Ferrucci, Luigi; Bandinelli, Stefania; Salfati, Elias; Manson, JoAnn E; Quach, Austin; Kusters, Cynthia D J; Kuh, Diana; Wong, Andrew; Teschendorff, Andrew E; Widschwendter, Martin; Ritz, Beate R; Absher, Devin; Assimes, Themistocles L; Horvath, Steve

    2016-08-16

    Although epigenetic processes have been linked to aging and disease in other systems, it is not yet known whether they relate to reproductive aging. Recently, we developed a highly accurate epigenetic biomarker of age (known as the "epigenetic clock"), which is based on DNA methylation levels. Here we carry out an epigenetic clock analysis of blood, saliva, and buccal epithelium using data from four large studies: the Women's Health Initiative (n = 1,864); Invecchiare nel Chianti (n = 200); Parkinson's disease, Environment, and Genes (n = 256); and the United Kingdom Medical Research Council National Survey of Health and Development (n = 790). We find that increased epigenetic age acceleration in blood is significantly associated with earlier menopause (P = 0.00091), bilateral oophorectomy (P = 0.0018), and a longer time since menopause (P = 0.017). Conversely, epigenetic age acceleration in buccal epithelium and saliva do not relate to age at menopause; however, a higher epigenetic age in saliva is exhibited in women who undergo bilateral oophorectomy (P = 0.0079), while a lower epigenetic age in buccal epithelium was found for women who underwent menopausal hormone therapy (P = 0.00078). Using genetic data, we find evidence of coheritability between age at menopause and epigenetic age acceleration in blood. Using Mendelian randomization analysis, we find that two SNPs that are highly associated with age at menopause exhibit a significant association with epigenetic age acceleration. Overall, our Mendelian randomization approach and other lines of evidence suggest that menopause accelerates epigenetic aging of blood, but mechanistic studies will be needed to dissect cause-and-effect relationships further. PMID:27457926

  6. 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.

  7. THE SPECIFIC ACCELERATION RATE IN LOOP-STRUCTURED SOLAR FLARES-IMPLICATIONS FOR ELECTRON ACCELERATION MODELS

    SciTech Connect

    Guo, Jingnan; Emslie, A. Gordon; Piana, Michele E-mail: piana@dima.unige.it

    2013-03-20

    We analyze electron flux maps based on RHESSI hard X-ray imaging spectroscopy data for a number of extended coronal-loop flare events. For each event, we determine the variation of the characteristic loop length L with electron energy E, and we fit this observed behavior with models that incorporate an extended acceleration region and an exterior 'propagation' region, and which may include collisional modification of the accelerated electron spectrum inside the acceleration region. The models are characterized by two parameters: the plasma density n in, and the longitudinal extent L{sub 0} of, the acceleration region. Determination of the best-fit values of these parameters permits inference of the volume that encompasses the acceleration region and of the total number of particles within it. It is then straightforward to compute values for the emission filling factor and for the specific acceleration rate (electrons s{sup -1} per ambient electron above a chosen reference energy). For the 24 events studied, the range of inferred filling factors is consistent with a value of unity. The inferred mean value of the specific acceleration rate above E{sub 0} = 20 keV is {approx}10{sup -2} s{sup -1}, with a 1{sigma} spread of about a half-order-of-magnitude above and below this value. We compare these values with the predictions of several models, including acceleration by large-scale, weak (sub-Dreicer) fields, by strong (super-Dreicer) electric fields in a reconnecting current sheet, and by stochastic acceleration processes.

  8. The FRC Acceleration Space Thruster (FAST) Experiment

    NASA Technical Reports Server (NTRS)

    Martin, Adam; Eskridge, Richard; Houts, Mike; Slough, John; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    The objective of the FRC (Field Reversed Configuration) Acceleration Space Thruster (FAST) Experiment is to investigate the use of a repetitive FRC source as a thruster, specifically for an NEP (nuclear electric propulsion) system. The Field Reversed Configuration is a plasmoid with a closed poloidal field line structure, and has been extensively studied as a fusion reactor core. An FRC thruster works by repetitively producing FRCs and accelerating them to high velocity. An FRC thruster should be capable of I(sub sp)'s in the range of 5,000 - 25,000 seconds and efficiencies in the range of 60 - 80 %. In addition, they can have thrust densities as high as 10(exp 6) N/m2, and as they are inductively formed, they do not suffer from electrode erosion. The jet-power should be scalable from the low to the high power regime. The FAST experiment consists of a theta-pinch formation chamber, followed by an acceleration stage. Initially, we will produce and accelerate single FRCs. The initial focus of the experiment will be on the ionization, formation and acceleration of a single plasmoid, so as to determine the likely efficiency and I(sub sp). Subsequently, we will modify the device for repetitive burst-mode operation (5-10 shots). A variety of diagnostics are or will be available for this work, including a HeNe interferometer, high-speed cameras, and a Thomson-scattering system. The status of the experiment will be described.

  9. Many human accelerated regions are developmental enhancers

    PubMed Central

    Capra, John A.; Erwin, Genevieve D.; McKinsey, Gabriel; Rubenstein, John L. R.; Pollard, Katherine S.

    2013-01-01

    The genetic changes underlying the dramatic differences in form and function between humans and other primates are largely unknown, although it is clear that gene regulatory changes play an important role. To identify regulatory sequences with potentially human-specific functions, we and others used comparative genomics to find non-coding regions conserved across mammals that have acquired many sequence changes in humans since divergence from chimpanzees. These regions are good candidates for performing human-specific regulatory functions. Here, we analysed the DNA sequence, evolutionary history, histone modifications, chromatin state and transcription factor (TF) binding sites of a combined set of 2649 non-coding human accelerated regions (ncHARs) and predicted that at least 30% of them function as developmental enhancers. We prioritized the predicted ncHAR enhancers using analysis of TF binding site gain and loss, along with the functional annotations and expression patterns of nearby genes. We then tested both the human and chimpanzee sequence for 29 ncHARs in transgenic mice, and found 24 novel developmental enhancers active in both species, 17 of which had very consistent patterns of activity in specific embryonic tissues. Of these ncHAR enhancers, five drove expression patterns suggestive of different activity for the human and chimpanzee sequence at embryonic day 11.5. The changes to human non-coding DNA in these ncHAR enhancers may modify the complex patterns of gene expression necessary for proper development in a human-specific manner and are thus promising candidates for understanding the genetic basis of human-specific biology. PMID:24218637

  10. Transversely accelerated ions in the topside ionosphere

    NASA Technical Reports Server (NTRS)

    Retterer, John M.; Chang, Tom; Jasperse, J. R.

    1994-01-01

    Data from the rocket campaigns Mechanism in the Auroral Region for Ion Energization (MARIE) and TOpside Probe of the Auroral Zone (TOPAZ) III, within regions of low-altitude transversely accelerated ions, are interpreted to explain the acceleration of the ions. Using the Monte Carlo kinetic technique to evaluate the ion heating produced by the simultaneously observed lower hybrid waves, we find that their observed electric field amplitudes are sufficient to explain the observed ion energies in the MARIE event. Much of the uncertainty in evaluating the efficiency of a plasma wave induced particle heating process which is dependent on a velocity resonance comes from the lack of information on the phase velocities of the waves. In the case of the MARIE observations, our modeling efforts show that features in the ion velocity distribution are consistent with the wave phase velocities inferred from interferometer measurements of wavelengths. The lower hybrid waves with which low-altitude transversely accelerated ions are associated are frequently observed to be concentrated in small-scale wave packets called 'spikelets'. We demonstrate through the scaling of the size of these wave packets that they are consistent with the theory of lower hybrid collapse. Using the Monte Carlo technique, we find that if the lower hybrid field energy is concentrated in these wave packets, it is still adequate to accelerate the ionospheric ions to the observed energies.

  11. Participation of the surface structure of Pharaonis phoborhodopsin, ppR and its A149S and A149V mutants, consisting of the C-terminal alpha-helix and E-F loop, in the complex-formation with the cognate transducer pHtrII, as revealed by site-directed 13C solid-state NMR.

    PubMed

    Kawamura, Izuru; Ikeda, Yoichi; Sudo, Yuki; Iwamoto, Masayuki; Shimono, Kazumi; Yamaguchi, Satoru; Tuzi, Satoru; Saitô, Hazime; Kamo, Naoki; Naito, Akira

    2007-01-01

    We have recorded 13C solid state NMR spectra of [3-13C]Ala-labeled pharaonis phoborhodopsin (ppR) and its mutants, A149S and A149V, complexed with the cognate transducer pharaonis halobacterial transducer II protein (pHtrII) (1-159), to gain insight into a possible role of their cytoplasmic surface structure including the C-terminal alpha-helix and E-F loop for stabilization of the 2:2 complex, by both cross-polarization magic angle spinning (CP-MAS) and dipolar decoupled (DD)-MAS NMR techniques. We found that 13C CP-MAS NMR spectra of [3-13C]Ala-ppR, A149S and A149V complexed with the transducer pHtrII are very similar, reflecting their conformation and dynamics changes caused by mutual interactions through the transmembrane alpha-helical surfaces. In contrast, their DD-MAS NMR spectral features are quite different between [3-13C]Ala-A149S and A149V in the complexes with pHtrII: 13C DD-MAS NMR spectrum of [3-13C]Ala-A149S complex is rather similar to that of the uncomplexed form, while the corresponding spectral feature of A149V complex is similar to that of ppR complex in the C-terminal tip region. This is because more flexible surface structure detected by the DD-MAS NMR spectra are more directly influenced by the dynamics changes than the CP-MAS NMR. It turned out, therefore, that an altered surface structure of A149S resulted in destabilized complex as viewed from the 13C NMR spectrum of the surface areas, probably because of modified conformation at the corner of the helix E in addition to the change of hydropathy. It is, therefore, concluded that the surface structure of ppR including the C-terminal alpha-helix and the E-F loops is directly involved in the stabilization of the complex through conformational stability of the helix E.

  12. Current Fragmentation and Particle Acceleration in Solar Flares

    NASA Astrophysics Data System (ADS)

    Cargill, P. J.; Vlahos, L.; Baumann, G.; Drake, J. F.; Nordlund, Å.

    2012-11-01

    Particle acceleration in solar flares remains an outstanding problem in plasma physics and space science. While the observed particle energies and timescales can perhaps be understood in terms of acceleration at a simple current sheet or turbulence site, the vast number of accelerated particles, and the fraction of flare energy in them, defies any simple explanation. The nature of energy storage and dissipation in the global coronal magnetic field is essential for understanding flare acceleration. Scenarios where the coronal field is stressed by complex photospheric motions lead to the formation of multiple current sheets, rather than the single monolithic current sheet proposed by some. The currents sheets in turn can fragment into multiple, smaller dissipation sites. MHD, kinetic and cellular automata models are used to demonstrate this feature. Particle acceleration in this environment thus involves interaction with many distributed accelerators. A series of examples demonstrate how acceleration works in such an environment. As required, acceleration is fast, and relativistic energies are readily attained. It is also shown that accelerated particles do indeed interact with multiple acceleration sites. Test particle models also demonstrate that a large number of particles can be accelerated, with a significant fraction of the flare energy associated with them. However, in the absence of feedback, and with limited numerical resolution, these results need to be viewed with caution. Particle in cell models can incorporate feedback and in one scenario suggest that acceleration can be limited by the energetic particles reaching the condition for firehose marginal stability. Contemporary issues such as footpoint particle acceleration are also discussed. It is also noted that the idea of a "standard flare model" is ill-conceived when the entire distribution of flare energies is considered.

  13. Mass spectrometry with accelerators.

    PubMed

    Litherland, A E; Zhao, X-L; Kieser, W E

    2011-01-01

    As one in a series of articles on Canadian contributions to mass spectrometry, this review begins with an outline of the history of accelerator mass spectrometry (AMS), noting roles played by researchers at three Canadian AMS laboratories. After a description of the unique features of AMS, three examples, (14)C, (10)Be, and (129)I are given to illustrate the methods. The capabilities of mass spectrometry have been extended by the addition of atomic isobar selection, molecular isobar attenuation, further ion acceleration, followed by ion detection and ion identification at essentially zero dark current or ion flux. This has been accomplished by exploiting the techniques and accelerators of atomic and nuclear physics. In 1939, the first principles of AMS were established using a cyclotron. In 1977 the selection of isobars in the ion source was established when it was shown that the (14)N(-) ion was very unstable, or extremely difficult to create, making a tandem electrostatic accelerator highly suitable for assisting the mass spectrometric measurement of the rare long-lived radioactive isotope (14)C in the environment. This observation, together with the large attenuation of the molecular isobars (13)CH(-) and (12)CH 2(-) during tandem acceleration and the observed very low background contamination from the ion source, was found to facilitate the mass spectrometry of (14)C to at least a level of (14)C/C ~ 6 × 10(-16), the equivalent of a radiocarbon age of 60,000 years. Tandem Accelerator Mass Spectrometry, or AMS, has now made possible the accurate radiocarbon dating of milligram-sized carbon samples by ion counting as well as dating and tracing with many other long-lived radioactive isotopes such as (10)Be, (26)Al, (36)Cl, and (129)I. The difficulty of obtaining large anion currents with low electron affinities and the difficulties of isobar separation, especially for the heavier mass ions, has prompted the use of molecular anions and the search for alternative

  14. On the initial state and consistency relations

    SciTech Connect

    Berezhiani, Lasha; Khoury, Justin E-mail: jkhoury@sas.upenn.edu

    2014-09-01

    We study the effect of the initial state on the consistency conditions for adiabatic perturbations. In order to be consistent with the constraints of General Relativity, the initial state must be diffeomorphism invariant. As a result, we show that initial wavefunctional/density matrix has to satisfy a Slavnov-Taylor identity similar to that of the action. We then investigate the precise ways in which modified initial states can lead to violations of the consistency relations. We find two independent sources of violations: i) the state can include initial non-Gaussianities; ii) even if the initial state is Gaussian, such as a Bogoliubov state, the modified 2-point function can modify the q-vector → 0 analyticity properties of the vertex functional and result in violations of the consistency relations.

  15. Consistency of homogenization schemes in linear poroelasticity

    NASA Astrophysics Data System (ADS)

    Pichler, Bernhard; Dormieux, Luc

    2008-08-01

    In view of extending classical micromechanics of poroelasticity to the non-saturated regime, one has to deal with different pore stresses which may be affected by the size and the shape of the pores. Introducing the macrostrain and these pore stresses as loading parameters, the macrostress of a representative volume element of a porous material can be derived by means of Levin's theorem or by means of the direct formulation of the stress average rule, respectively. A consistency requirement for a given homogenization scheme is obtained from the condition that the two approaches should yield identical results. Classical approaches (Mori-Tanaka scheme, self-consistent scheme) are shown to be only conditionally consistent. In contrast, the Ponte Castañeda-Willis scheme proves to provide consistent descriptions both of porous matrix-inclusion composites and of porous polycrystals. To cite this article: B. Pichler, L. Dormieux, C. R. Mecanique 336 (2008).

  16. Safety performance functions incorporating design consistency variables.

    PubMed

    Montella, Alfonso; Imbriani, Lella Liana

    2015-01-01

    Highway design which ensures that successive elements are coordinated in such a way as to produce harmonious and homogeneous driver performances along the road is considered consistent and safe. On the other hand, an alignment which requires drivers to handle high speed gradients and does not meet drivers' expectancy is considered inconsistent and produces higher crash frequency. To increase the usefulness and the reliability of existing safety performance functions and contribute to solve inconsistencies of existing highways as well as inconsistencies arising in the design phase, we developed safety performance functions for rural motorways that incorporate design consistency measures. Since the design consistency variables were used only for curves, two different sets of models were fitted for tangents and curves. Models for the following crash characteristics were fitted: total, single-vehicle run-off-the-road, other single vehicle, multi vehicle, daytime, nighttime, non-rainy weather, rainy weather, dry pavement, wet pavement, property damage only, slight injury, and severe injury (including fatal). The design consistency parameters in this study are based on operating speed models developed through an instrumented vehicle equipped with a GPS continuous speed tracking from a field experiment conducted on the same motorway where the safety performance functions were fitted (motorway A16 in Italy). Study results show that geometric design consistency has a significant effect on safety of rural motorways. Previous studies on the relationship between geometric design consistency and crash frequency focused on two-lane rural highways since these highways have the higher crash rates and are generally characterized by considerable inconsistencies. Our study clearly highlights that the achievement of proper geometric design consistency is a key design element also on motorways because of the safety consequences of design inconsistencies. The design consistency measures

  17. Consistency relations for non-Gaussianity

    NASA Astrophysics Data System (ADS)

    Li, Miao; Wang, Yi

    2008-09-01

    We investigate consistency relations for non-Gaussianity. We provide a model-independent dynamical proof for the consistency relation for three-point correlation functions from the Hamiltonian and field redefinition. This relation can be applied to single-field inflation, multi-field inflation and the curvaton scenario. This relation can also be generalized to n-point correlation functions up to arbitrary order in perturbation theory and with arbitrary number of loops.

  18. Double layers acting as particles accelerators

    SciTech Connect

    Sanduloviciu, M.; Lozneanu, E.

    1995-12-31

    It is shown that self-consistent stable and unstable double layers generated in plasma after a self-organisation process are able to accelerate charged particles. The implication of cosmic double layers (Dls) in the acceleration of electrical charged particles long been advocated by Alfven and his Stockholm school is today disputed by argument that static electric fields associated with Dls are conservative and consequently the line integral of the electric field outside the DL balances the line integral inside it. Related with this dispute we will evidence some, so far not considered, facts which are in our opinion arguments that aurora Dls are able to energize particles. For justifying this assertion we start from recent experimental results concerning the phenomenology of self-consistent Dls whose generation involve beside ionisations the neutrals excitations which are at tile origin of the light phenomena as those observed in auroras.

  19. A seismologically consistent expression for the total area and volume of earthquake-triggered landsliding

    NASA Astrophysics Data System (ADS)

    Marc, Odin; Hovius, Niels; Meunier, Patrick; Gorum, Tolga; Uchida, Taro

    2016-04-01

    We present a new, seismologically consistent expression for the total area and volume of populations of earthquake-triggered landslides. This model builds on a set of scaling relationships between key parameters, such as landslide spatial density, seismic ground acceleration, fault length, earthquake source depth, and seismic moment. To assess the model we have assembled and normalized a catalog of landslide inventories for 40 shallow, continental earthquakes. Low landscape steepness causes systematic overprediction of the total area and volume of landslides. When this effect is accounted for, the model predicts the total landslide volume of 63% of 40 cases to within a factor 2 of the volume estimated from observations (R2=0.76). The prediction of total landslide area is also sensitive to the landscape steepness, but less so than the total volume, and it appears to be sensitive to controls on the landslide size-frequency distribution, and possibly the shaking duration. Some outliers are likely associated with exceptionally strong rock mass in the epicentral area, while others may be related to seismic source complexities ignored by the model. However, the close match between prediction and estimate for about two thirds of cases in our database suggests that rock mass strength is similar in many cases and that our simple seismic model is often adequate, despite the variety of lithologies and tectonic settings covered. This makes our expression suitable for integration into landscape evolution models and application to the anticipation or rapid assessment of secondary hazards associated with earthquakes.

  20. Accelerators for Cancer Therapy

    DOE R&D Accomplishments Database

    Lennox, Arlene J.

    2000-05-30

    The vast majority of radiation treatments for cancerous tumors are given using electron linacs that provide both electrons and photons at several energies. Design and construction of these linacs are based on mature technology that is rapidly becoming more and more standardized and sophisticated. The use of hadrons such as neutrons, protons, alphas, or carbon, oxygen and neon ions is relatively new. Accelerators for hadron therapy are far from standardized, but the use of hadron therapy as an alternative to conventional radiation has led to significant improvements and refinements in conventional treatment techniques. This paper presents the rationale for radiation therapy, describes the accelerators used in conventional and hadron therapy, and outlines the issues that must still be resolved in the emerging field of hadron therapy.

  1. SUPERDIFFUSIVE SHOCK ACCELERATION

    SciTech Connect

    Perri, S.; Zimbardo, G.

    2012-05-10

    The theory of diffusive shock acceleration is extended to the case of superdiffusive transport, i.e., when the mean square deviation grows proportionally to t{sup {alpha}}, with {alpha} > 1. Superdiffusion can be described by a statistical process called Levy random walk, in which the propagator is not a Gaussian but it exhibits power-law tails. By using the propagator appropriate for Levy random walk, it is found that the indices of energy spectra of particles are harder than those obtained where a normal diffusion is envisaged, with the spectral index decreasing with the increase of {alpha}. A new scaling for the acceleration time is also found, allowing substantially shorter times than in the case of normal diffusion. Within this framework we can explain a number of observations of flat spectra in various astrophysical and heliospheric contexts, for instance, for the Crab Nebula and the termination shock of the solar wind.

  2. Hardware Accelerated Simulated Radiography

    SciTech Connect

    Laney, D; Callahan, S; Max, N; Silva, C; Langer, S; Frank, R

    2005-04-12

    We present the application of hardware accelerated volume rendering algorithms to the simulation of radiographs as an aid to scientists designing experiments, validating simulation codes, and understanding experimental data. The techniques presented take advantage of 32 bit floating point texture capabilities to obtain validated solutions to the radiative transport equation for X-rays. An unsorted hexahedron projection algorithm is presented for curvilinear hexahedra that produces simulated radiographs in the absorption-only regime. A sorted tetrahedral projection algorithm is presented that simulates radiographs of emissive materials. We apply the tetrahedral projection algorithm to the simulation of experimental diagnostics for inertial confinement fusion experiments on a laser at the University of Rochester. We show that the hardware accelerated solution is faster than the current technique used by scientists.

  3. Accelerated expansion through interaction

    SciTech Connect

    Zimdahl, Winfried

    2009-05-01

    Interactions between dark matter and dark energy with a given equation of state are known to modify the cosmic dynamics. On the other hand, the strength of these interactions is subject to strong observational constraints. Here we discuss a model in which the transition from decelerated to accelerated expansion of the Universe arises as a pure interaction phenomenon. Various cosmological scenarios that describe a present stage of accelerated expansion, like the {lambda}CDM model or a (generalized) Chaplygin gas, follow as special cases for different interaction rates. This unifying view on the homogeneous and isotropic background level is accompanied by a non-adiabatic perturbation dynamics which can be seen as a consequence of a fluctuating interaction rate.

  4. Hypervelocity plate acceleration

    SciTech Connect

    Marsh, S.P.; Tan, T.H.

    1991-01-01

    Shock tubes have been used to accelerate 1.5-mm-thick stainless steel plates to high velocity while retaining their integrity. The fast shock tubes are 5.1-cm-diameter, 15.2-cm-long cylinders of PBX-9501 explosive containing a 1.1-cm-diameter cylindrical core of low-density polystyrene foam. The plates have been placed directly in contact with one face of the explosive system. Plane-wave detonation was initiated on the opposite face. A Mach disk was formed in the imploding styrofoam core, which provided the impulse required to accelerate the metal plate to high velocity. Parametric studies were made on this system to find the effect of varying plate metal, plate thickness, foam properties, and addition of a barrel. A maximum plate velocity of 9.0 km/s has been observed. 6 refs., 17 figs.

  5. Pulsed electromagnetic gas acceleration

    NASA Technical Reports Server (NTRS)

    Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

    1971-01-01

    Experimental data were combined with one-dimensional conservation relations to yield information on the energy deposition ratio in a parallel-plate accelerator, where the downstream flow was confined to a constant area channel. Approximately 70% of the total input power was detected in the exhaust flow, of which only about 20% appeared as directed kinetic energy, thus implying that a downstream expansion to convert chamber enthalpy into kinetic energy must be an important aspect of conventional high power MPD arcs. Spectroscopic experiments on a quasi-steady MPD argon accelerator verified the presence of A(III) and the absence of A(I), and indicated an azimuthal structure in the jet related to the mass injection locations. Measurements of pressure in the arc chamber and impact pressure in the exhaust jet using a piezocrystal backed by a Plexiglas rod were in good agreement with the electromagnetic thrust model.

  6. Commissioning the GTA accelerator

    SciTech Connect

    Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Bowling, S.; Brown, S.; Cole, R.; Gilpatrick, J.D.; Garnett, R.; Guy, F.W.; Ingalls, W.B.; Johnson, K.F.; Kerstiens, D.; Little, C.; Lohsen, R.A.; Lloyd, S.; Lysenko, W.P.; Mottershead, C.T.; Neuschaefer, G.; Power, J.; Rusthoi, D.P.; Sandoval, D.P. Stevens, R.R. Jr.; Vaughn, G.; Wadlinger, E.A.; Yuan, V.; Connolly, R.; Weiss, R.; Saadatmand, K.

    1992-09-01

    The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth`s magnetic field and travel in straight lines unless they enter the earth`s atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H{sup -} beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor.

  7. Adaptive control for accelerators

    DOEpatents

    Eaton, Lawrie E.; Jachim, Stephen P.; Natter, Eckard F.

    1991-01-01

    An adaptive feedforward control loop is provided to stabilize accelerator beam loading of the radio frequency field in an accelerator cavity during successive pulses of the beam into the cavity. A digital signal processor enables an adaptive algorithm to generate a feedforward error correcting signal functionally determined by the feedback error obtained by a beam pulse loading the cavity after the previous correcting signal was applied to the cavity. Each cavity feedforward correcting signal is successively stored in the digital processor and modified by the feedback error resulting from its application to generate the next feedforward error correcting signal. A feedforward error correcting signal is generated by the digital processor in advance of the beam pulse to enable a composite correcting signal and the beam pulse to arrive concurrently at the cavity.

  8. Self-consistent asset pricing models

    NASA Astrophysics Data System (ADS)

    Malevergne, Y.; Sornette, D.

    2007-08-01

    We discuss the foundations of factor or regression models in the light of the self-consistency condition that the market portfolio (and more generally the risk factors) is (are) constituted of the assets whose returns it is (they are) supposed to explain. As already reported in several articles, self-consistency implies correlations between the return disturbances. As a consequence, the alphas and betas of the factor model are unobservable. Self-consistency leads to renormalized betas with zero effective alphas, which are observable with standard OLS regressions. When the conditions derived from internal consistency are not met, the model is necessarily incomplete, which means that some sources of risk cannot be replicated (or hedged) by a portfolio of stocks traded on the market, even for infinite economies. Analytical derivations and numerical simulations show that, for arbitrary choices of the proxy which are different from the true market portfolio, a modified linear regression holds with a non-zero value αi at the origin between an asset i's return and the proxy's return. Self-consistency also introduces “orthogonality” and “normality” conditions linking the betas, alphas (as well as the residuals) and the weights of the proxy portfolio. Two diagnostics based on these orthogonality and normality conditions are implemented on a basket of 323 assets which have been components of the S&P500 in the period from January 1990 to February 2005. These two diagnostics show interesting departures from dynamical self-consistency starting about 2 years before the end of the Internet bubble. Assuming that the CAPM holds with the self-consistency condition, the OLS method automatically obeys the resulting orthogonality and normality conditions and therefore provides a simple way to self-consistently assess the parameters of the model by using proxy portfolios made only of the assets which are used in the CAPM regressions. Finally, the factor decomposition with the

  9. Modulational effects in accelerators

    SciTech Connect

    Satogata, T.

    1997-12-01

    We discuss effects of field modulations in accelerators, specifically those that can be used for operational beam diagnostics and beam halo control. In transverse beam dynamics, combined effects of nonlinear resonances and tune modulations influence diffusion rates with applied tune modulation has been demonstrated. In the longitudinal domain, applied RF phase and voltage modulations provide mechanisms for parasitic halo transport, useful in slow crystal extraction. Experimental experiences with transverse tune and RF modulations are also discussed.

  10. Linear induction accelerator

    DOEpatents

    Buttram, M.T.; Ginn, J.W.

    1988-06-21

    A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities. 4 figs.

  11. Accelerated plate tectonics.

    PubMed

    Anderson, D L

    1975-03-21

    The concept of a stressed elastic lithospheric plate riding on a viscous asthenosphere is used to calculate the recurrence interval of great earthquakes at convergent plate boundaries, the separation of decoupling and lithospheric earthquakes, and the migration pattern of large earthquakes along an arc. It is proposed that plate motions accelerate after great decoupling earthquakes and that most of the observed plate motions occur during short periods of time, separated by periods of relative quiescence.

  12. ION ACCELERATION SYSTEM

    DOEpatents

    Luce, J.S.; Martin, J.A.

    1960-02-23

    Well focused, intense ion beams are obtained by providing a multi- apertured source grid in front of an ion source chamber and an accelerating multi- apertured grid closely spaced from and in alignment with the source grid. The longest dimensions of the elongated apertures in the grids are normal to the direction of the magnetic field used with the device. Large ion currents may be withdrawn from the source, since they do not pass through any small focal region between the grids.

  13. Computer assisted accelerator tuning

    SciTech Connect

    Boyd, J.K.

    1993-04-14

    The challenge of tuning an induction accelerator in real time has been addressed with the new TUNE GUIDE code. The code initializes a beam at a particular position using a tracer particle representation of the phase space. The particles are transported, using a matrix formulation, element by element along the beamline assuming that the field of a solenoid, or steering element is constant over its length. The other allowed elements are gaps and drift sections. A great deal of effort has been spent programming TUNE GUIDE to operate under the IBMPC Windows 3.1 system. This system features an intuitive, menu driven interface, which provides an ability to rapidly change beamline component parameter values. Consequently various accelerator setups can be explored and new values determined in real time while the accelerator is operating. In addition the code has the capability of varying a capability value over a range and then plotting the resulting beam properties, such as radius or centroid position, at a down stream position. Element parameter editing is also included along with an on-line hyper text oriented help package.

  14. Accelerator mass spectrometry.

    PubMed

    Hellborg, Ragnar; Skog, Göran

    2008-01-01

    In this overview the technique of accelerator mass spectrometry (AMS) and its use are described. AMS is a highly sensitive method of counting atoms. It is used to detect very low concentrations of natural isotopic abundances (typically in the range between 10(-12) and 10(-16)) of both radionuclides and stable nuclides. The main advantages of AMS compared to conventional radiometric methods are the use of smaller samples (mg and even sub-mg size) and shorter measuring times (less than 1 hr). The equipment used for AMS is almost exclusively based on the electrostatic tandem accelerator, although some of the newest systems are based on a slightly different principle. Dedicated accelerators as well as older "nuclear physics machines" can be found in the 80 or so AMS laboratories in existence today. The most widely used isotope studied with AMS is 14C. Besides radiocarbon dating this isotope is used in climate studies, biomedicine applications and many other fields. More than 100,000 14C samples are measured per year. Other isotopes studied include 10Be, 26Al, 36Cl, 41Ca, 59Ni, 129I, U, and Pu. Although these measurements are important, the number of samples of these other isotopes measured each year is estimated to be less than 10% of the number of 14C samples.

  15. ACCELERATION INTEGRATING MEANS

    DOEpatents

    Wilkes, D.F.

    1961-08-29

    An acceleration responsive device is described. A housing has at one end normally open electrical contacts and contains a piston system with a first part of non-magnetic material having metering orifices in the side walls for forming an air bearing between it and the walls of the housing; this first piston part is normally held against the other end of the housing from the noted contacts by a second piston or reset part. The reset part is of partly magnetic material, is separable from the flrst piston part, and is positioned within the housing intermediate the contacts and the first piston part. A magnet carried by the housing imposes a retaining force upon the reset part, along with a helical compression spring that is between the reset part and the end with the contacts. When a predetermined acceleration level is attained, the reset part overcomes the bias or retaining force provided by the magnet and the spring'' snaps'' into a depression in the housing adjacent the contacts. The first piston part is then free to move toward the contacts with its movement responsive tc acceleration forces and the metering orifices. (AEC)

  16. Quality and Consistency of the NASA Ocean Color Data Record

    NASA Technical Reports Server (NTRS)

    Franz, Bryan A.

    2012-01-01

    The NASA Ocean Biology Processing Group (OBPG) recently reprocessed the multimission ocean color time-series from SeaWiFS, MODIS-Aqua, and MODIS-Terra using common algorithms and improved instrument calibration knowledge. Here we present an analysis of the quality and consistency of the resulting ocean color retrievals, including spectral water-leaving reflectance, chlorophyll a concentration, and diffuse attenuation. Statistical analysis of satellite retrievals relative to in situ measurements will be presented for each sensor, as well as an assessment of consistency in the global time-series for the overlapping periods of the missions. Results will show that the satellite retrievals are in good agreement with in situ measurements, and that the sensor ocean color data records are highly consistent over the common mission lifespan for the global deep oceans, but with degraded agreement in higher productivity, higher complexity coastal regions.

  17. Consistency-based rectification of nonrigid registrations

    PubMed Central

    Gass, Tobias; Székely, Gábor; Goksel, Orcun

    2015-01-01

    Abstract. We present a technique to rectify nonrigid registrations by improving their group-wise consistency, which is a widely used unsupervised measure to assess pair-wise registration quality. While pair-wise registration methods cannot guarantee any group-wise consistency, group-wise approaches typically enforce perfect consistency by registering all images to a common reference. However, errors in individual registrations to the reference then propagate, distorting the mean and accumulating in the pair-wise registrations inferred via the reference. Furthermore, the assumption that perfect correspondences exist is not always true, e.g., for interpatient registration. The proposed consistency-based registration rectification (CBRR) method addresses these issues by minimizing the group-wise inconsistency of all pair-wise registrations using a regularized least-squares algorithm. The regularization controls the adherence to the original registration, which is additionally weighted by the local postregistration similarity. This allows CBRR to adaptively improve consistency while locally preserving accurate pair-wise registrations. We show that the resulting registrations are not only more consistent, but also have lower average transformation error when compared to known transformations in simulated data. On clinical data, we show improvements of up to 50% target registration error in breathing motion estimation from four-dimensional MRI and improvements in atlas-based segmentation quality of up to 65% in terms of mean surface distance in three-dimensional (3-D) CT. Such improvement was observed consistently using different registration algorithms, dimensionality (two-dimensional/3-D), and modalities (MRI/CT). PMID:26158083

  18. The effect of stochastic re-acceleration on the energy spectrum of shock-accelerated protons

    SciTech Connect

    Afanasiev, Alexandr; Vainio, Rami; Kocharov, Leon

    2014-07-20

    The energy spectra of particles in gradual solar energetic particle (SEP) events do not always have a power-law form attributed to the diffusive shock acceleration mechanism. In particular, the observed spectra in major SEP events can take the form of a broken (double) power law. In this paper, we study the effect of a process that can modify the power-law spectral form produced by the diffusive shock acceleration: the stochastic re-acceleration of energetic protons by enhanced Alfvénic turbulence in the downstream region of a shock wave. There are arguments suggesting that this process can be important when the shock propagates in the corona. We consider a coronal magnetic loop traversed by a shock and perform Monte Carlo simulations of interactions of shock-accelerated protons with Alfvén waves in the loop. The wave-particle interactions are treated self-consistently, so the finiteness of the available turbulent energy is taken into account. The initial energy spectrum of particles is taken to be a power law. The simulations reveal that the stochastic re-acceleration leads either to the formation of a spectrum that is described in a wide energy range by a power law (although the resulting power-law index is different from the initial one) or to a broken power-law spectrum. The resulting spectral form is determined by the ratio of the energy density of shock-accelerated protons to the wave energy density in the shock's downstream region.

  19. Overview of accelerators in medicine

    SciTech Connect

    Lennox, A.J. |

    1993-06-01

    Accelerators used for medicine include synchrotrons, cyclotrons, betatrons, microtrons, and electron, proton, and light ion linacs. Some accelerators which were formerly found only at physics laboratories are now being considered for use in hospital-based treatment and diagnostic facilities. This paper presents typical operating parameters for medical accelerators and gives specific examples of clinical applications for each type of accelerator, with emphasis on recent developments in the field.

  20. Preliminary consideration of a double, 480 GeV, fast cycling proton accelerator for production of neutrino beams at Fermilab

    SciTech Connect

    Piekarz, Henryk; Hays, Steven; /Fermilab

    2007-03-01

    We propose to build the DSF-MR (Double Super-Ferric Main Ring), 480 GeV, fast-cycling (2 second repetition rate) two-beam proton accelerator in the Main Ring tunnel of Fermilab. This accelerator design is based on the super-ferric magnet technology developed for the VLHC, and extended recently to the proposed LER injector for the LHC and fast cycling SF-SPS at CERN. The DSF-MR accelerator system will constitute the final stage of the proton source enabling production of two neutrino beams separated by 2 second time period. These beams will be sent alternately to two detectors located at {approx} 3000 km and {approx} 7500 km away from Fermilab. It is expected that combination of the results from these experiments will offer more than 3 order of magnitudes increased sensitivity for detection and measurement of neutrino oscillations with respect to expectations in any current experiment, and thus may truly enable opening the window into the physics beyond the Standard Model. We examine potential sites for the long baseline neutrino detectors accepting beams from Fermilab. The current injection system consisting of 400 MeV Linac, 8 GeV Booster and the Main Injector can be used to accelerate protons to 45 GeV before transferring them to the DSF-MR. The implementation of the DSF-MR will allow for an 8-fold increase in beam power on the neutrino production target. In this note we outline the proposed new arrangement of the Fermilab accelerator complex. We also briefly describe the DSF-MR magnet design and its power supply, and discuss necessary upgrade of the Tevatron RF system for the use with the DSF-MR accelerator. Finally, we outline the required R&D, cost estimate and possible timeline for the implementation of the DSF-MR accelerator.

  1. Induction accelerators for the phase rotator system

    SciTech Connect

    Reginato, Lou; Yu, Simon; Vanecek, Dave

    2001-07-30

    The principle of magnetic induction has been applied to the acceleration of high current beams in betatrons and a variety of induction accelerators. The linear induction accelerator (LIA) consists of a simple nonresonant structure where the drive voltage is applied to an axially symmetric gap that encloses a toroidal ferromagnetic material. The change in flux in the magnetic core induces an axial electric field that provides particle acceleration. This simple nonresonant (low Q) structure acts as a single turn transformer that can accelerate from hundreds of amperes to tens of kiloamperes, basically only limited by the drive impedance. The LIA is typically a low gradient structure that can provide acceleration fields of varying shapes and time durations from tens of nanoseconds to several microseconds. The efficiency of the LIA depends on the beam current and can exceed 50% if the beam current exceeds the magnetization current required by the ferromagnetic material. The acceleration voltage available is simply given by the expression V=A dB/dt. Hence, for a given cross section of material, the beam pulse duration influences the energy gain. Furthermore, a premium is put on minimizing the diameter, which impacts the total weight or cost of the magnetic material. The diameter doubly impacts the cost of the LIA since the power (cost) to drive the cores is proportional to the volume as well. The waveform requirements during the beam pulse makes it necessary to make provisions in the pulsing system to maintain the desired dB/dt during the useful part of the acceleration cycle. This is typically done two ways, by using the final stage of the pulse forming network (PFN) and by the pulse compensation network usually in close proximity of the acceleration cell. The choice of magnetic materials will be made by testing various materials both ferromagnetic and ferrimagnetic. These materials will include the nickel-iron, silicon steel amorphous and various types of ferrites not

  2. Accelerating cleanup: Paths to closure

    SciTech Connect

    1998-06-01

    This report describes the status of Environmental Management`s (EM`s) cleanup program and a direction forward to complete achievement of the 2006 vision. Achieving the 2006 vision results in significant benefits related to accomplishing EM program objectives. As DOE sites accelerate cleanup activities, risks to public health, the environment, and worker safety and health are all reduced. Finding more efficient ways to conduct work can result in making compliance with applicable environmental requirements easier to achieve. Finally, as cleanup activities at sites are completed, the EM program can focus attention and resources on the small number of sites with more complex cleanup challenges. Chapter 1 describes the process by which this report has been developed and what it hopes to accomplish, its relationship to the EM decision-making process, and a general background of the EM mission and program. Chapter 2 describes how the site-by-site projections were constructed, and summarizes, for each of DOE`s 11 Operations/Field Offices, the projected costs and schedules for completing the cleanup mission. Chapter 3 presents summaries of the detailed cleanup projections from three of the 11 Operations/Field Offices: Rocky Flats (Colorado), Richland (Washington), and Savannah River (South Carolina). The remaining eight Operations/Field Office summaries are in Appendix E. Chapter 4 reviews the cost drivers, budgetary constraints, and performance enhancements underlying the detailed analysis of the 353 projects that comprise EM`s accelerated cleanup and closure effort. Chapter 5 describes a management system to support the EM program. Chapter 6 provides responses to the general comments received on the February draft of this document.

  3. Particle acceleration on Galactic scales

    NASA Astrophysics Data System (ADS)

    Axford, W. I.

    The history of and current ideas concerning the origin of cosmic rays in the Galaxy and in extragalactic sources are surveyed. The observed properties of Galactic cosmic rays and shock acceleration are discussed. It is argued that shock acceleration in various guises is an essential and conceptually the most economical acceleration mechanism.

  4. Consistency and derangements in brane tilings

    NASA Astrophysics Data System (ADS)

    Hanany, Amihay; Jejjala, Vishnu; Ramgoolam, Sanjaye; Seong, Rak-Kyeong

    2016-09-01

    Brane tilings describe Lagrangians (vector multiplets, chiral multiplets, and the superpotential) of four-dimensional { N }=1 supersymmetric gauge theories. These theories, written in terms of a bipartite graph on a torus, correspond to worldvolume theories on N D3-branes probing a toric Calabi–Yau threefold singularity. A pair of permutations compactly encapsulates the data necessary to specify a brane tiling. We show that geometric consistency for brane tilings, which ensures that the corresponding quantum field theories are well behaved, imposes constraints on the pair of permutations, restricting certain products constructed from the pair to have no one-cycles. Permutations without one-cycles are known as derangements. We illustrate this formulation of consistency with known brane tilings. Counting formulas for consistent brane tilings with an arbitrary number of chiral bifundamental fields are written down in terms of delta functions over symmetric groups.

  5. Consistency and derangements in brane tilings

    NASA Astrophysics Data System (ADS)

    Hanany, Amihay; Jejjala, Vishnu; Ramgoolam, Sanjaye; Seong, Rak-Kyeong

    2016-09-01

    Brane tilings describe Lagrangians (vector multiplets, chiral multiplets, and the superpotential) of four-dimensional { N }=1 supersymmetric gauge theories. These theories, written in terms of a bipartite graph on a torus, correspond to worldvolume theories on N D3-branes probing a toric Calabi-Yau threefold singularity. A pair of permutations compactly encapsulates the data necessary to specify a brane tiling. We show that geometric consistency for brane tilings, which ensures that the corresponding quantum field theories are well behaved, imposes constraints on the pair of permutations, restricting certain products constructed from the pair to have no one-cycles. Permutations without one-cycles are known as derangements. We illustrate this formulation of consistency with known brane tilings. Counting formulas for consistent brane tilings with an arbitrary number of chiral bifundamental fields are written down in terms of delta functions over symmetric groups.

  6. Personalized recommendation based on unbiased consistence

    NASA Astrophysics Data System (ADS)

    Zhu, Xuzhen; Tian, Hui; Zhang, Ping; Hu, Zheng; Zhou, Tao

    2015-08-01

    Recently, in physical dynamics, mass-diffusion-based recommendation algorithms on bipartite network provide an efficient solution by automatically pushing possible relevant items to users according to their past preferences. However, traditional mass-diffusion-based algorithms just focus on unidirectional mass diffusion from objects having been collected to those which should be recommended, resulting in a biased causal similarity estimation and not-so-good performance. In this letter, we argue that in many cases, a user's interests are stable, and thus bidirectional mass diffusion abilities, no matter originated from objects having been collected or from those which should be recommended, should be consistently powerful, showing unbiased consistence. We further propose a consistence-based mass diffusion algorithm via bidirectional diffusion against biased causality, outperforming the state-of-the-art recommendation algorithms in disparate real data sets, including Netflix, MovieLens, Amazon and Rate Your Music.

  7. Temporal and kinematic consistency predict sequence awareness.

    PubMed

    Jaynes, Molly J; Schieber, Marc H; Mink, Jonathan W

    2016-10-01

    Many human motor skills can be represented as a hierarchical series of movement patterns. Awareness of underlying patterns can improve performance and decrease cognitive load. Subjects (n = 30) tapped a finger sequence with changing stimulus-to-response mapping and a common movement sequence. Thirteen subjects (43 %) became aware that they were tapping a familiar movement sequence during the experiment. Subjects who became aware of the underlying motor pattern tapped with greater kinematic and temporal consistency from task onset, but consistency was not sufficient for awareness. We found no effect of age, musical experience, tapping evenness, or inter-key-interval on awareness of the pattern in the motor response. We propose that temporal or kinematic consistency reinforces a pattern representation, but cognitive engagement with the contents of the sequence is necessary to bring the pattern to conscious awareness. These findings predict benefit for movement strategies that limit temporal and kinematic variability during motor learning. PMID:27324192

  8. Simulations of ion acceleration at non-relativistic shocks. I. Acceleration efficiency

    SciTech Connect

    Caprioli, D.; Spitkovsky, A.

    2014-03-10

    We use two-dimensional and three-dimensional hybrid (kinetic ions-fluid electrons) simulations to investigate particle acceleration and magnetic field amplification at non-relativistic astrophysical shocks. We show that diffusive shock acceleration operates for quasi-parallel configurations (i.e., when the background magnetic field is almost aligned with the shock normal) and, for large sonic and Alfvénic Mach numbers, produces universal power-law spectra ∝p {sup –4}, where p is the particle momentum. The maximum energy of accelerated ions increases with time, and it is only limited by finite box size and run time. Acceleration is mainly efficient for parallel and quasi-parallel strong shocks, where 10%-20% of the bulk kinetic energy can be converted to energetic particles and becomes ineffective for quasi-perpendicular shocks. Also, the generation of magnetic turbulence correlates with efficient ion acceleration and vanishes for quasi-perpendicular configurations. At very oblique shocks, ions can be accelerated via shock drift acceleration, but they only gain a factor of a few in momentum and their maximum energy does not increase with time. These findings are consistent with the degree of polarization and the morphology of the radio and X-ray synchrotron emission observed, for instance, in the remnant of SN 1006. We also discuss the transition from thermal to non-thermal particles in the ion spectrum (supra-thermal region) and we identify two dynamical signatures peculiar of efficient particle acceleration, namely, the formation of an upstream precursor and the alteration of standard shock jump conditions.

  9. Self-Consistent Non-Stationary Theory of Multipactor in DLA Structures

    SciTech Connect

    Sinitsyn, O. V.; Nusinovich, G. S.; Antonsen, T. M.; Kishek, R.

    2009-01-22

    In this paper a non-stationary self-consistent theoretical model of multipactor in dielectric loaded accelerator structures is proposed. In comparison with our previous work, the effects of the cylindricity are included. The corresponding numerical implementation of the model is described and some simulation results are shown.

  10. Self-Consistent Non-Stationary Theory of Multipactor in DLA Structures

    NASA Astrophysics Data System (ADS)

    Sinitsyn, O. V.; Nusinovich, G. S.; Antonsen, T. M.; Kishek, R.

    2009-01-01

    In this paper a non-stationary self-consistent theoretical model of multipactor in dielectric loaded accelerator structures is proposed. In comparison with our previous work, the effects of the cylindricity are included. The corresponding numerical implementation of the model is described and some simulation results are shown.

  11. Kinematics and hydrodynamics of linear acceleration in eels, Anguilla rostrata.

    PubMed

    Tytell, Eric D

    2004-12-22

    The kinematics and hydrodynamics of routine linear accelerations were studied in American eels, Anguilla rostrata, using high-speed video and particle image velocimetry. Eels were examined both during steady swimming at speeds from 0.6 to 1.9 body lengths (L) per second and during accelerations from -1.4 to 1.3 L s(-2). Multiple regression of the acceleration and steady swimming speed on the body kinematics suggests that eels primarily change their tail-tip velocity during acceleration. By contrast, the best predictor of steady swimming speed is body wave speed, keeping tail-tip velocity an approximately constant fraction of the swimming velocity. Thus, during steady swimming, Strouhal number does not vary with speed, remaining close to 0.32, but during acceleration, it deviates from the steady value. The kinematic changes during acceleration are indicated hydrodynamically by axial fluid momentum in the wake. During steady swimming, the wake consists of lateral jets of fluid and has minimal net axial momentum, which reflects a balance between thrust and drag. During acceleration, those jets rotate to point downstream, adding axial momentum to the fluid. The amount of added momentum correlates with the acceleration, but is greater than the necessary inertial force by 2.8+/-0.6 times, indicating a substantial acceleration reaction.

  12. ON PARTICLE ACCELERATION RATE IN GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Sagi, Eran; Nakar, Ehud

    2012-04-10

    It is well known that collisionless shocks are major sites of particle acceleration in the universe, but the details of the acceleration process are still not well understood. The particle acceleration rate, which can shed light on the acceleration process, is rarely measured in astrophysical environments. Here, we use observations of gamma-ray burst (GRB) afterglows, which are weakly magnetized relativistic collisionless shocks in ion-electron plasma, to constrain the rate of particle acceleration in such shocks. We find, based on X-ray and GeV afterglows, an acceleration rate that is most likely very fast, approaching the Bohm limit, when the shock Lorentz factor is in the range of {Gamma} {approx} 10-100. In that case X-ray observations may be consistent with no amplification of the magnetic field in the shock upstream region. We examine the X-ray afterglow of GRB 060729, which is observed for 642 days showing a sharp decay in the flux starting about 400 days after the burst, when the shock Lorentz factor is {approx}5. We find that inability to accelerate X-ray-emitting electrons at late time provides a natural explanation for the sharp decay, and that also in that case acceleration must be rather fast, and cannot be more than a 100 times slower than the Bohm limit. We conclude that particle acceleration is most likely fast in GRB afterglows, at least as long as the blast wave is ultrarelativistic.

  13. Consistent matter couplings for Plebanski gravity

    NASA Astrophysics Data System (ADS)

    Tennie, Felix; Wohlfarth, Mattias N. R.

    2010-11-01

    We develop a scheme for the minimal coupling of all standard types of tensor and spinor field matter to Plebanski gravity. This theory is a geometric reformulation of vacuum general relativity in terms of two-form frames and connection one-forms, and provides a covariant basis for various quantization approaches. Using the spinor formalism we prove the consistency of the newly proposed matter coupling by demonstrating the full equivalence of Plebanski gravity plus matter to Einstein-Cartan gravity. As a by-product we also show the consistency of some previous suggestions for matter actions.

  14. Consistent Data Distribution Over Optical Links

    NASA Technical Reports Server (NTRS)

    Palumbo, Daniel L.

    1988-01-01

    Fiber optics combined with IDE's provide consistent data communication between fault-tolerant computers. Data-transmission-checking system designed to provide consistent and reliable data communications for fault-tolerant and highly reliable computers. New technique performs variant of algorithm for fault-tolerant computers and uses fiber optics and independent decision elements (IDE's) to require fewer processors and fewer transmissions of messages. Enables fault-tolerant computers operating at different levels of redundancy to communicate with each other over triply redundant bus. Level of redundancy limited only by maximum number of wavelengths active on bus.

  15. Dynamically consistent Jacobian inverse for mobile manipulators

    NASA Astrophysics Data System (ADS)

    Ratajczak, Joanna; Tchoń, Krzysztof

    2016-06-01

    By analogy to the definition of the dynamically consistent Jacobian inverse for robotic manipulators, we have designed a dynamically consistent Jacobian inverse for mobile manipulators built of a non-holonomic mobile platform and a holonomic on-board manipulator. The endogenous configuration space approach has been exploited as a source of conceptual guidelines. The new inverse guarantees a decoupling of the motion in the operational space from the forces exerted in the endogenous configuration space and annihilated by the dual Jacobian inverse. A performance study of the new Jacobian inverse as a tool for motion planning is presented.

  16. Accuracy and consistency of modern elastomeric pumps.

    PubMed

    Weisman, Robyn S; Missair, Andres; Pham, Phung; Gutierrez, Juan F; Gebhard, Ralf E

    2014-01-01

    Continuous peripheral nerve blockade has become a popular method of achieving postoperative analgesia for many surgical procedures. The safety and reliability of infusion pumps are dependent on their flow rate accuracy and consistency. Knowledge of pump rate profiles can help physicians determine which infusion pump is best suited for their clinical applications and specific patient population. Several studies have investigated the accuracy of portable infusion pumps. Using methodology similar to that used by Ilfeld et al, we investigated the accuracy and consistency of several current elastomeric pumps. PMID:25140510

  17. Anticholinergic substances: A single consistent conformation

    PubMed Central

    Pauling, Peter; Datta, Narayandas

    1980-01-01

    An interactive computer-graphics analysis of 24 antagonists of acetylcholine at peripheral autonomic post-ganglionic (muscarinic) nervous junctions and at similar junctions in the central nervous system, the crystal structures of which are known, has led to the determination of a single, consistent, energetically favorable conformation for all 24 substances, although their observed crystal structure conformations vary widely. The absolute configuration and the single, consistent (ideal) conformation of the chemical groups required for maximum anticholinergic activity are described quantitatively. Images PMID:16592775

  18. Particle accelerators test cosmological theory

    SciTech Connect

    Schramm, D.N.; Steigman, G.

    1988-06-01

    Over the past decade two subfields of science, cosmology and elementary-particle physics, have become married in a symbiotic relationship that has produced a number of exciting offspring. These offspring are beginning to yield insights on the creation of spacetime and matter at epochs as early as 10 to the minus 43 to 10 to the minus 35 second after the birth of the universe in the primordial explosion known as the big bang. Important clues to the nature of the big bang itself may even come from a theory currently under development, known as the ultimate theory of everything (T.E.O.). A T.E.O. would describe all the interactions among the fundamental particles in a single bold stroke. Now that cosmology ahs begun to make predictions about elementary-particle physics, it has become conceivable that those cosmological predictions could be checked with carefully controlled accelerator experiments. It has taken more than 10 years for accelerators to reach the point where they can do the appropriate experiments, but the experiments are now in fact in progress. The preliminary results confirm the predictions of cosmology. The cosmological prediction the authors have been concerned with pertains to setting limits on the number of fundamental particles of matter. It appears that there are 12 fundamental particles, as well as their corresponding antiparticles. Six of the fundamental particles are quarks. The other six are leptons. The 12 particles are grouped in three families, each family consisting of four members. Cosmology suggests there must be a finite number of families and, further limits the possible range of to small values: only three or at most four families exist. 7 figs.

  19. Variable Acceleration Force Calibration System (VACS)

    NASA Technical Reports Server (NTRS)

    Rhew, Ray D.; Parker, Peter A.; Johnson, Thomas H.; Landman, Drew

    2014-01-01

    Conventionally, force balances have been calibrated manually, using a complex system of free hanging precision weights, bell cranks, and/or other mechanical components. Conventional methods may provide sufficient accuracy in some instances, but are often quite complex and labor-intensive, requiring three to four man-weeks to complete each full calibration. To ensure accuracy, gravity-based loading is typically utilized. However, this often causes difficulty when applying loads in three simultaneous, orthogonal axes. A complex system of levers, cranks, and cables must be used, introducing increased sources of systematic error, and significantly increasing the time and labor intensity required to complete the calibration. One aspect of the VACS is a method wherein the mass utilized for calibration is held constant, and the acceleration is changed to thereby generate relatively large forces with relatively small test masses. Multiple forces can be applied to a force balance without changing the test mass, and dynamic forces can be applied by rotation or oscillating acceleration. If rotational motion is utilized, a mass is rigidly attached to a force balance, and the mass is exposed to a rotational field. A large force can be applied by utilizing a large rotational velocity. A centrifuge or rotating table can be used to create the rotational field, and fixtures can be utilized to position the force balance. The acceleration may also be linear. For example, a table that moves linearly and accelerates in a sinusoidal manner may also be utilized. The test mass does not have to move in a path that is parallel to the ground, and no re-leveling is therefore required. Balance deflection corrections may be applied passively by monitoring the orientation of the force balance with a three-axis accelerometer package. Deflections are measured during each test run, and adjustments with respect to the true applied load can be made during the post-processing stage. This paper will

  20. Localized Ionospheric Particle Acceleration and Wave Acceleration of Auroral Ions: Amicist Data Set

    NASA Technical Reports Server (NTRS)

    Lynch, Kristina A.

    1999-01-01

    Research supported by this grant covered two main topics: auroral ion acceleration from ELF-band wave activity, and from VLF-spikelet (lower hybrid solitary structure) wave activity. Recent auroral sounding rocket data illustrate the relative significance of various mechanisms for initiating auroral ion outflow. Two nightside mechanisms are shown in detail. The first mechanism is ion acceleration within lower hybrid solitary wave events. The new data from this two payload mission show clearly that: (1) these individual events are spatially localized to scales approximately 100 m wide perpendicular to B, in agreement with previous investigations of these structures, and (2) that the probability of occurrence of the events is greatest at times of maximum VLF wave intensity. The second mechanism is ion acceleration by broadband, low frequency electrostatic waves, observed in a 30 km wide region at the poleward edge of the arc. The ion fluxes from the two mechanisms are compared and it is shown that while lower hybrid solitary structures do indeed accelerate ions in regions of intense VLF waves, the outflow from the electrostatic ion wave acceleration region is dominant for the aurora investigated by this sounding rocket, AMICIST. The fluxes are shown to be consistent with DE-1 and Freja outflow measurements, indicating that the AMICIST observations show the low altitude, microphysical signatures of nightside auroral outflow. In this paper, we present a review of sounding rocket observations of the ion acceleration seen nightside auroral zone lower hybrid solitary structures. Observations from Topaz3, Amicist, and Phaze2 are presented on various spatial scales, including the two-point measurements of the Amicist mission. From this collection of observations, we will demonstrate the following characteristics of transverse ion acceleration (TAI) in LHSS. The ion acceleration process is narrowly confined to 90 degrees pitch angle, in spatially confined regions of up to a

  1. A global assessment of accelerations in surface mass transport

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoping; Heflin, Michael B.

    2015-08-01

    Water mass transport in the Earth's dynamic surface layer of atmosphere, cryosphere, and hydrosphere driven by various global change processes has complex spatiotemporal patterns. Here we determine global patterns and regional mean values of accelerations in surface mass variations during the Gravity Recovery and Climate Experiment (GRACE) mission's data span from 2002.2 to 2015.0. GRACE gravity data are supplemented by surface deformation from 607 Global Navigation Satellite System stations, an ocean bottom pressure model, satellite laser ranging, and loose a priori knowledge on mass variation regimes incorporating high-resolution geographic boundaries. While Greenland and West Antarctica have strong negative accelerations, Alaska and the Arctic Ocean show significant positive accelerations. In addition, the accelerations are not constant in time with some regions showing considerable variability due to irregular interannual changes. No evidence of significant nonsteric mean sea level acceleration has been found, but the uncertainty is quite large.

  2. Consistency of Students' Pace in Online Learning

    ERIC Educational Resources Information Center

    Hershkovitz, Arnon; Nachmias, Rafi

    2009-01-01

    The purpose of this study is to investigate the consistency of students' behavior regarding their pace of actions over sessions within an online course. Pace in a session is defined as the number of logged actions divided by session length (in minutes). Log files of 6,112 students were collected, and datasets were constructed for examining pace…

  3. Developing consistent time series landsat data products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Landsat series satellite has provided earth observation data record continuously since early 1970s. There are increasing demands on having a consistent time series of Landsat data products. In this presentation, I will summarize the work supported by the USGS Landsat Science Team project from 20...

  4. Image recognition and consistency of response

    NASA Astrophysics Data System (ADS)

    Haygood, Tamara M.; Ryan, John; Liu, Qing Mary A.; Bassett, Roland; Brennan, Patrick C.

    2012-02-01

    Purpose: To investigate the connection between conscious recognition of an image previously encountered in an experimental setting and consistency of response to the experimental question.
    Materials and Methods: Twenty-four radiologists viewed 40 frontal chest radiographs and gave their opinion as to the position of a central venous catheter. One-to-three days later they again viewed 40 frontal chest radiographs and again gave their opinion as to the position of the central venous catheter. Half of the radiographs in the second set were repeated images from the first set and half were new. The radiologists were asked of each image whether it had been included in the first set. For this study, we are evaluating only the 20 repeated images. We used the Kruskal-Wallis test and Fisher's exact test to determine the relationship between conscious recognition of a previously interpreted image and consistency in interpretation of the image.
    Results. There was no significant correlation between recognition of the image and consistency in response regarding the position of the central venous catheter. In fact, there was a trend in the opposite direction, with radiologists being slightly more likely to give a consistent response with respect to images they did not recognize than with respect to those they did recognize.
    Conclusion: Radiologists' recognition of previously-encountered images in an observer-performance study does not noticeably color their interpretation on the second encounter.

  5. Consistent Visual Analyses of Intrasubject Data

    ERIC Educational Resources Information Center

    Kahng, SungWoo; Chung, Kyong-Mee; Gutshall, Katharine; Pitts, Steven C.; Kao, Joyce; Girolami, Kelli

    2010-01-01

    Visual inspection of single-case data is the primary method of interpretation of the effects of an independent variable on a dependent variable in applied behavior analysis. The purpose of the current study was to replicate and extend the results of DeProspero and Cohen (1979) by reexamining the consistency of visual analysis across raters. We…

  6. Environmental Decision Support with Consistent Metrics

    EPA Science Inventory

    One of the most effective ways to pursue environmental progress is through the use of consistent metrics within a decision making framework. The US Environmental Protection Agency’s Sustainable Technology Division has developed TRACI, the Tool for the Reduction and Assessment of...

  7. 36 CFR 241.22 - Consistency determinations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... FISH AND WILDLIFE Conservation of Fish, Wildlife, and Their Habitat, Chugach National Forest, Alaska... conservation of fish, wildlife, and their habitat. A use or activity may be determined to be consistent if it will not materially interfere with or detract from the conservation of fish, wildlife and their...

  8. 36 CFR 241.22 - Consistency determinations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... FISH AND WILDLIFE Conservation of Fish, Wildlife, and Their Habitat, Chugach National Forest, Alaska... conservation of fish, wildlife, and their habitat. A use or activity may be determined to be consistent if it will not materially interfere with or detract from the conservation of fish, wildlife and their...

  9. 36 CFR 241.22 - Consistency determinations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... FISH AND WILDLIFE Conservation of Fish, Wildlife, and Their Habitat, Chugach National Forest, Alaska... conservation of fish, wildlife, and their habitat. A use or activity may be determined to be consistent if it will not materially interfere with or detract from the conservation of fish, wildlife and their...

  10. 24 CFR 91.510 - Consistency determinations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Consistency determinations. 91.510 Section 91.510 Housing and Urban Development Office of the Secretary, Department of Housing and Urban... HOPWA grant is a city that is the most populous unit of general local government in an EMSA, it...

  11. Effecting Consistency across Curriculum: A Case Study

    ERIC Educational Resources Information Center

    Devasagayam, P. Raj; Mahaffey, Thomas R.

    2008-01-01

    Continuous quality improvement is the clarion call across all business schools which is driving the emphasis on assessing the attainment of learning outcomes. An issue that deems special attention in assurance of learning outcomes is related to consistency across courses and, more specifically, across multiple sections of the same course taught by…

  12. Consistency and stability of recombinant fermentations.

    PubMed

    Wiebe, M E; Builder, S E

    1994-01-01

    Production of proteins of consistent quality in heterologous, genetically-engineered expression systems is dependent upon identifying the manufacturing process parameters which have an impact on product structure, function, or purity, validating acceptable ranges for these variables, and performing the manufacturing process as specified. One of the factors which may affect product consistency is genetic instability of the primary product sequence, as well as instability of genes which code for proteins responsible for post-translational modification of the product. Approaches have been developed for mammalian expression systems to assure that product quality is not changing through mechanisms of genetic instability. Sensitive protein analytical methods, particularly peptide mapping, are used to evaluate product structure directly, and are more sensitive in detecting genetic instability than is direct genetic analysis by nucleotide sequencing of the recombinant gene or mRNA. These methods are being employed to demonstrate that the manufacturing process consistently yields a product of defined structure from cells cultured through the range of cell ages used in the manufacturing process and well beyond the maximum cell age defined for the process. The combination of well designed validation studies which demonstrate consistent product quality as a function of cell age, and rigorous quality control of every product lot by sensitive protein analytical methods provide the necessary assurance that product structure is not being altered through mechanisms of mutation and selection.

  13. RULE GENERALITY AND CONSISTENCY IN MATHEMATICS LEARNING.

    ERIC Educational Resources Information Center

    SCANDURA, JOSEPH M.

    PSYCHOLOGICAL PRINCIPLES INVOLVED WITH RULE GENERALITY (DEGREE OF NONSPECIFICITY) AND PERFORMANCE CONSISTENCY IN MATHEMATICAL PRESENTATIONS WERE STUDIED. SPECIFICALLY, THE PURPOSES WERE (1) TO DETERMINE IF TEST BEHAVIOR CONFORMS TO THE SCOPE OF A VERBALLY ADMINISTERED TEST RULE, (2) TO EXPLORE THE INTERPRETABILITY OF VERBAL TEST RULES, AND (3) TO…

  14. Taking Another Look: Sensuous, Consistent Form.

    ERIC Educational Resources Information Center

    Townley, Mary Ross

    1983-01-01

    There is a natural progression from making single objects to creating sculpture. By modeling the forms of objects like funnels and light bulbs, students become aware of the quality of curves and the edges of angles. Sculptural form in architecture can be understood as consistency in the forms. (CS)

  15. Consistency of Toddler Engagement across Two Settings

    ERIC Educational Resources Information Center

    Aguiar, Cecilia; McWilliam, R. A.

    2013-01-01

    This study documented the consistency of child engagement across two settings, toddler child care classrooms and mother-child dyadic play. One hundred twelve children, aged 14-36 months (M = 25.17, SD = 6.06), randomly selected from 30 toddler child care classrooms from the district of Porto, Portugal, participated. Levels of engagement were…

  16. Consistency and variability in functional localisers

    PubMed Central

    Duncan, Keith J.; Pattamadilok, Chotiga; Knierim, Iris; Devlin, Joseph T.

    2009-01-01

    A critical assumption underlying the use of functional localiser scans is that the voxels identified as the functional region-of-interest (fROI) are essentially the same as those activated by the main experimental manipulation. Intra-subject variability in the location of the fROI violates this assumption, reducing the sensitivity of the analysis and biasing the results. Here we investigated consistency and variability in fROIs in a set of 45 volunteers. They performed two functional localiser scans to identify word- and object-sensitive regions of ventral and lateral occipito-temporal cortex, respectively. In the main analyses, fROIs were defined as the category-selective voxels in each region and consistency was measured as the spatial overlap between scans. Consistency was greatest when minimally selective thresholds were used to define “active” voxels (p < 0.05 uncorrected), revealing that approximately 65% of the voxels were commonly activated by both scans. In contrast, highly selective thresholds (p < 10− 4 to 10− 6) yielded the lowest consistency values with less than 25% overlap of the voxels active in both scans. In other words, intra-subject variability was surprisingly high, with between one third and three quarters of the voxels in a given fROI not corresponding to those activated in the main task. This level of variability stands in striking contrast to the consistency seen in retinotopically-defined areas and has important implications for designing robust but efficient functional localiser scans. PMID:19289173

  17. VLHC accelerator physics

    SciTech Connect

    Michael Blaskiewicz et al.

    2001-11-01

    A six-month design study for a future high energy hadron collider was initiated by the Fermilab director in October 2000. The request was to study a staged approach where a large circumference tunnel is built that initially would house a low field ({approx}2 T) collider with center-of-mass energy greater than 30 TeV and a peak (initial) luminosity of 10{sup 34} cm{sup -2}s{sup -1}. The tunnel was to be scoped, however, to support a future upgrade to a center-of-mass energy greater than 150 TeV with a peak luminosity of 2 x 10{sup 34} cm{sup -2} sec{sup -1} using high field ({approx} 10 T) superconducting magnet technology. In a collaboration with Brookhaven National Laboratory and Lawrence Berkeley National Laboratory, a report of the Design Study was produced by Fermilab in June 2001. 1 The Design Study focused on a Stage 1, 20 x 20 TeV collider using a 2-in-1 transmission line magnet and leads to a Stage 2, 87.5 x 87.5 TeV collider using 10 T Nb{sub 3}Sn magnet technology. The article that follows is a compilation of accelerator physics designs and computational results which contributed to the Design Study. Many of the parameters found in this report evolved during the study, and thus slight differences between this text and the Design Study report can be found. The present text, however, presents the major accelerator physics issues of the Very Large Hadron Collider as examined by the Design Study collaboration and provides a basis for discussion and further studies of VLHC accelerator parameters and design philosophies.

  18. Acceleration of reaction in charged microdroplets.

    PubMed

    Lee, Jae Kyoo; Banerjee, Shibdas; Nam, Hong Gil; Zare, Richard N

    2015-11-01

    Using high-resolution mass spectrometry, we have studied the synthesis of isoquinoline in a charged electrospray droplet and the complexation between cytochrome c and maltose in a fused droplet to investigate the feasibility of droplets to drive reactions (both covalent and noncovalent interactions) at a faster rate than that observed in conventional bulk solution. In both the cases we found marked acceleration of reaction, by a factor of a million or more in the former and a factor of a thousand or more in the latter. We believe that carrying out reactions in microdroplets (about 1-15 μm in diameter corresponding to 0·5 pl - 2 nl) is a general method for increasing reaction rates. The mechanism is not presently established but droplet evaporation and droplet confinement of reagents appear to be two important factors among others. In the case of fused water droplets, evaporation has been shown to be almost negligible during the flight time from where droplet fusion occurs and the droplets enter the heated capillary inlet of the mass spectrometer. This suggests that (1) evaporation is not responsible for the acceleration process in aqueous droplet fusion and (2) the droplet-air interface may play a significant role in accelerating the reaction. We argue that this 'microdroplet chemistry' could be a remarkable alternative to accelerate slow and difficult reactions, and in conjunction with mass spectrometry, it may provide a new arena to study chemical and biochemical reactions in a confined environment.

  19. Acceleration of reaction in charged microdroplets.

    PubMed

    Lee, Jae Kyoo; Banerjee, Shibdas; Nam, Hong Gil; Zare, Richard N

    2015-11-01

    Using high-resolution mass spectrometry, we have studied the synthesis of isoquinoline in a charged electrospray droplet and the complexation between cytochrome c and maltose in a fused droplet to investigate the feasibility of droplets to drive reactions (both covalent and noncovalent interactions) at a faster rate than that observed in conventional bulk solution. In both the cases we found marked acceleration of reaction, by a factor of a million or more in the former and a factor of a thousand or more in the latter. We believe that carrying out reactions in microdroplets (about 1-15 μm in diameter corresponding to 0·5 pl - 2 nl) is a general method for increasing reaction rates. The mechanism is not presently established but droplet evaporation and droplet confinement of reagents appear to be two important factors among others. In the case of fused water droplets, evaporation has been shown to be almost negligible during the flight time from where droplet fusion occurs and the droplets enter the heated capillary inlet of the mass spectrometer. This suggests that (1) evaporation is not responsible for the acceleration process in aqueous droplet fusion and (2) the droplet-air interface may play a significant role in accelerating the reaction. We argue that this 'microdroplet chemistry' could be a remarkable alternative to accelerate slow and difficult reactions, and in conjunction with mass spectrometry, it may provide a new arena to study chemical and biochemical reactions in a confined environment. PMID:26537403

  20. BE STAR DISK MODELS IN CONSISTENT VERTICAL HYDROSTATIC EQUILIBRIUM

    SciTech Connect

    Sigut, T. A. A.; McGill, M. A.; Jones, C. E. E-mail: mmcgill@astro.uwo.ca

    2009-07-10

    A popular model for the circumstellar disks of Be stars is that of a geometrically thin disk with a density in the equatorial plane that drops as a power law of distance from the star. It is usually assumed that the vertical structure of such a disk (in the direction parallel to the stellar rotation axis) is governed by the hydrostatic equilibrium set by the vertical component of the star's gravitational acceleration. Previous radiative equilibrium models for such disks have usually been computed assuming a fixed density structure. This introduces an inconsistency as the gas density is not allowed to respond to temperature changes and the resultant disk model is not in vertical, hydrostatic equilibrium. In this work, we modify the BEDISK code of Sigut and Jones so that it enforces a hydrostatic equilibrium consistent with the temperature solution. We compare the disk densities, temperatures, H{alpha} line profiles, and near-IR excesses predicted by such models with those computed from models with a fixed density structure. We find that the fixed models can differ substantially from the consistent hydrostatic models when the disk density is high enough that the circumstellar disk develops a cool (T {approx}< 10, 000 K) equatorial region close to the parent star. Based on these new hydrostatic disks, we also predict an approximate relation between the (global) density-averaged disk temperature and the T{sub eff} of the central star, covering the full range of central Be star spectral types.

  1. Self-Consistent Superthermal Electron Effects on Plasmaspheric Refilling

    NASA Technical Reports Server (NTRS)

    Liemohn, M. W.; Khazanov, G. V.; Moore, T. E.; Guiter, S. M.

    1997-01-01

    The effects of self-consistently including superthermal electrons in the definition of the ambipolar electric field are investigated for the case of plasmaspheric refilling after a geomagnetic storm. By using the total electron population in the hydrodynamic equations, a method for incorporating superthermal electron parameters in the electric field and electron temperature calculation is developed. Also, the ambipolar electric field is included in the kinetic equation for the superthermal electrons through a change of variables using the total energy and the first adiabatic invariant. Calculations based on these changes are performed by coupling time-dependent models of the thermal plasma and superthermal electrons. Results from this treatment of the electric field and the self-consistent development of the solution are discussed in detail. Specifically, there is a decreased thermal electron density in the plasmasphere during the first few minutes of refilling, a slightly accelerated proton shock front, and a decreased superthermal electron flux due to the deceleration by the electric field. The timescales of plasmaspheric refilling are discussed and determined to be somewhat shorter than previously calculated for the thermal plasma and superthermal electron population due to the effects of the field-aligned potential.

  2. Classical and Quantum Consistency of the DGP Model

    NASA Astrophysics Data System (ADS)

    Nicolis, Alberto; Rattazzi, Riccardo

    2004-06-01

    We study the Dvali-Gabadadze-Porrati model by the method of the boundary effective action. The truncation of this action to the bending mode pi consistently describes physics in a wide range of regimes both at the classical and at the quantum level. The Vainshtein effect, which restores agreement with precise tests of general relativity, follows straightforwardly. We give a simple and general proof of stability, i.e. absence of ghosts in the fluctuations, valid for most of the relevant cases, like for instance the spherical source in asymptotically flat space. However we confirm that around certain interesting self-accelerating cosmological solutions there is a ghost. We consider the issue of quantum corrections. Around flat space pi becomes strongly coupled below a macroscopic length of 1000 km, thus impairing the predictivity of the model. Indeed the tower of higher dimensional operators which is expected by a generic UV completion of the model limits predictivity at even larger length scales. We outline a non-generic but consistent choice of counterterms for which this disaster does not happen and for which the model remains calculable and successful in all the astrophysical situations of interest. By this choice, the extrinsic curvature Kmunu acts roughly like a dilaton field controlling the strength of the interaction and the cut-off scale at each space-time point. At the surface of Earth the cutoff is ~ 1 cm but it is unlikely that the associated quantum effects be observable in table top experiments.

  3. Accelerating Commercial Remote Sensing

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Through the Visiting Investigator Program (VIP) at Stennis Space Center, Community Coffee was able to use satellites to forecast coffee crops in Guatemala. Using satellite imagery, the company can produce detailed maps that separate coffee cropland from wild vegetation and show information on the health of specific crops. The data can control coffee prices and eventually may be used to optimize application of fertilizers, pesticides and irrigation. This would result in maximal crop yields, minimal pollution and lower production costs. VIP is a mechanism involving NASA funding designed to accelerate the growth of commercial remote sensing by promoting general awareness and basic training in the technology.

  4. Accelerated Innovation Pilot

    NASA Technical Reports Server (NTRS)

    Davis, Jeffrey

    2012-01-01

    Opportunities: I. Engage NASA team (examples) a) Research and technology calls . provide suggestions to AES, HRP, OCT. b) Use NASA@Work to solicit other ideas; (possibly before R+D calls). II. Stimulate collaboration (examples) a) NHHPC. b) Wharton Mack Center for Technological Innovation (Feb 2013). c) International ] DLR ] :envihab (July 2013). d) Accelerated research models . NSF, Myelin Repair Foundation. III. Engage public Prizes (open platform: InnoCentive, yet2.com, NTL; Rice Business Plan, etc.) IV. Use same methods to engage STEM.

  5. Ion wave breaking acceleration

    NASA Astrophysics Data System (ADS)

    Liu, B.; Meyer-ter-Vehn, J.; Bamberg, K.-U.; Ma, W. J.; Liu, J.; He, X. T.; Yan, X. Q.; Ruhl, H.

    2016-07-01

    Laser driven ion wave breaking acceleration (IWBA) in plasma wakefields is investigated by means of a one-dimensional (1D) model and 1D/3D particle-in-cell (PIC) simulations. IWBA operates in relativistic transparent plasma for laser intensities in the range of 1020- 1023 W /cm2 . The threshold for IWBA is identified in the plane of plasma density and laser amplitude. In the region just beyond the threshold, self-injection takes place only for a fraction of ions and in a limited time period. This leads to well collimated ion pulses with peaked energy spectra, in particular for 3D geometry.

  6. A facility for accelerator research and education at Fermilab

    SciTech Connect

    Church, Mike; Nagaitsev, Sergei; /Fermilab

    2009-01-01

    Fermilab is currently constructing the 'SRF Test Accelerator at the New Muon Lab' (NML). NML consists of a photo-emitted RF electron gun, followed by a bunch compressor, low energy test beamlines, SCRF accelerating structures, and high energy test beamlines. The initial primary purpose of NML will be to test superconducting RF accelerating modules for the ILC and for Fermilab's 'Project X' - a proposal for a high intensity proton source. The unique capability of NML will be to test these modules under conditions of high intensity electron beams with ILC-like beam parameters. In addition NML incorporates a photoinjector which offers significant tunability and especially the possibility to generate a bright electron beam with brightness comparable to state-of-the-art accelerators. This opens the exciting possibility of also using NML for fundamental beams research and tests of new concepts in beam manipulations and acceleration, instrumentation, and the applications of beams.

  7. The electron accelerator for the AWAKE experiment at CERN

    NASA Astrophysics Data System (ADS)

    Pepitone, K.; Doebert, S.; Burt, G.; Chevallay, E.; Chritin, N.; Delory, C.; Fedosseev, V.; Hessler, Ch.; McMonagle, G.; Mete, O.; Verzilov, V.; Apsimon, R.

    2016-09-01

    The AWAKE collaboration prepares a proton driven plasma wakefield acceleration experiment using the SPS beam at CERN. A long proton bunch extracted from the SPS interacts with a high power laser and a 10 m long rubidium vapour plasma cell to create strong wakefields allowing sustained electron acceleration. The electron bunch to probe these wakefields is supplied by a 20 MeV electron accelerator. The electron accelerator consists of an RF-gun and a short booster structure. This electron source should provide beams with intensities between 0.1 and 1 nC, bunch lengths between 0.3 and 3 ps and an emittance of the order of 2 mm mrad. The wide range of parameters should cope with the uncertainties and future prospects of the planned experiments. The layout of the electron accelerator, its instrumentation and beam dynamics simulations are presented.

  8. Effect of gasoline octane quality on vehicle acceleration performance

    SciTech Connect

    Not Available

    1991-07-01

    A study was conducted under the auspices of the Coordinating Research Council, Inc. (CRC) to assess the potential effects of gasoline octane quality on vehicle acceleration performance. Twelve participating laboratories, representing both the oil and the automotive industries, tested a total of 182 vehicles as part of the 1989 CRC Octane Number Requirement Survey. The vehicles consisted of 78 with electronic knock control systems and 104 without. All testing was performed using the 1989/1990 CRC FBRU fuel series. The results showed that acceleration performance of vehicles with knock sensors was significantly affected by gasoline octane quality. Octane effects on acceleration performance were most pronounced at maximum-throttle (detent) conditions and at octane levels below the vehicles' octane requirements; however, some knock-sensor vehicles did show improved acceleration performance with fuels at octane levels above the octane number requirement. Acceleration performance in non-knock sensor vehicles was unaffected by octane quality.

  9. Shock Acceleration of Solar Energetic Protons: The First 10 Minutes

    NASA Technical Reports Server (NTRS)

    Ng, Chee K.; Reames, Donald V.

    2008-01-01

    Proton acceleration at a parallel coronal shock is modeled with self-consistent Alfven wave excitation and shock transmission. 18 - 50 keV seed protons at 0.1% of plasma proton density are accelerated in 10 minutes to a power-law intensity spectrum rolling over at 300 MeV by a 2500km s-1 shock traveling outward from 3.5 solar radius, for typical coronal conditions and low ambient wave intensities. Interaction of high-energy protons of large pitch-angles with Alfven waves amplified by low-energy protons of small pitch angles is key to rapid acceleration. Shock acceleration is not significantly retarded by sunward streaming protons interacting with downstream waves. There is no significant second-order Fermi acceleration.

  10. Effects of changing from non-accelerated to accelerated MRI for follow-up in brain atrophy measurement.

    PubMed

    Leung, Kelvin K; Malone, Ian M; Ourselin, Sebastien; Gunter, Jeffrey L; Bernstein, Matt A; Thompson, Paul M; Jack, Clifford R; Weiner, Michael W; Fox, Nick C

    2015-02-15

    Stable MR acquisition is essential for reliable measurement of brain atrophy in longitudinal studies. One attractive recent advance in MRI is to speed up acquisition using parallel imaging (e.g. reducing volumetric T1-weighted acquisition scan times from around 9 to 5 min). In some studies, a decision to change to an accelerated acquisition may have been deliberately taken, while in others repeat scans may occasionally be accidentally acquired with an accelerated acquisition. In ADNI, non-accelerated and accelerated scans were acquired in the same scanning session on each individual. We investigated the impact on brain atrophy as measured by k-means normalized boundary shift integral (KN-BSI) and deformation-based morphometry when changing from non-accelerated to accelerated MRI acquisitions over a 12-month interval using scans of 422 subjects from ADNI. KN-BSIs were calculated using both a non-accelerated baseline scan and non-accelerated 12-month scans (i.e. consistent acquisition), and a non-accelerated baseline scan and an accelerated 12-month scan (i.e. changed acquisition). Fluid-based non-rigid registration was also performed on those scans to estimate the brain atrophy rate. We found that the effect on KN-BSI and fluid-based non-rigid registration depended on the scanner manufacturer. For KN-BSI, in Philips and Siemens scanners, the change had very little impact on the measured atrophy rate (increase of 0.051% in Philips and -0.035% in Siemens from consistent acquisition to changed acquisition), whereas, in GE, the change caused a mean reduction of 0.65% in the brain atrophy rate. This is likely due to the difference in tissue contrast between gray matter and cerebrospinal fluid in the non-accelerated and accelerated scans in GE, which uses IR-FSPGR instead of MP-RAGE. For fluid-based non-rigid registration, the change caused a mean increase of 0.29% in the brain atrophy rate in the changed acquisition compared with consistent acquisition in Philips

  11. Overview of accelerators with potential use in homeland security

    SciTech Connect

    Garnett, Robert W.

    2015-01-01

    Quite a broad range of accelerators have been applied to solving many of the challenging problems related to homeland security and defense. These accelerator systems range from relatively small, simple, and compact, to large and complex, based on the specific application requirements. They have been used or proposed as sources of primary and secondary probe beams for applications such as radiography and to induce specific reactions that are key signatures for detecting conventional explosives or fissile material. A brief overview and description of these accelerator systems, their specifications, and application will be presented. Some recent technology trends will also be discussed.

  12. Overview of accelerators with potential use in homeland security

    DOE PAGES

    Garnett, Robert W.

    2015-01-01

    Quite a broad range of accelerators have been applied to solving many of the challenging problems related to homeland security and defense. These accelerator systems range from relatively small, simple, and compact, to large and complex, based on the specific application requirements. They have been used or proposed as sources of primary and secondary probe beams for applications such as radiography and to induce specific reactions that are key signatures for detecting conventional explosives or fissile material. A brief overview and description of these accelerator systems, their specifications, and application will be presented. Some recent technology trends will also bemore » discussed.« less

  13. Overview of Accelerators with Potential Use in Homeland Security

    NASA Astrophysics Data System (ADS)

    Garnett, Robert W.

    Quite a broad range of accelerators have been applied to solving many of the challenging problems related to homeland security and defense. These accelerator systems range from relatively small, simple, and compact, to large and complex, based on the specific application requirements. They have been used or proposed as sources of primary and secondary probe beams for applications such as radiography and to induce specific reactions that are key signatures for detecting conventional explosives or fissile material. A brief overview and description of these accelerator systems, their specifications, and application will be presented. Some recent technology trends will also be discussed.

  14. Comparing methods of quantifying tibial acceleration slope.

    PubMed

    Duquette, Adriana M; Andrews, David M

    2010-05-01

    Considerable variability in tibial acceleration slope (AS) values, and different interpretations of injury risk based on these values, have been reported. Acceleration slope variability may be due in part to variations in the quantification methods used. Therefore, the purpose of this study was to quantify differences in tibial AS values determined using end points at various percentage ranges between impact and peak tibial acceleration, as a function of either amplitude or time. Tibial accelerations were recorded from 20 participants (21.8 +/- 2.9 years, 1.7 m +/- 0.1 m, 75.1 kg +/- 17.0 kg) during 24 unshod heel impacts using a human pendulum apparatus. Nine ranges were tested from 5-95% (widest range) to 45-55% (narrowest range) at 5% increments. AS(Amplitude) values increased consistently from the widest to narrowest ranges, whereas the AS(Time) values remained essentially the same. The magnitudes of AS(Amplitude) values were significantly higher and more sensitive to changes in percentage range than AS(Time) values derived from the same impact data. This study shows that tibial AS magnitudes are highly dependent on the method used to calculate them. Researchers are encouraged to carefully consider the method they use to calculate AS so that equivalent comparisons and assessments of injury risk across studies can be made.

  15. Ground test accelerator control system software

    SciTech Connect

    Burczyk, L.; Dalesio, R.; Dingler, R.; Hill, J.; Howell, J.A.; Kerstiens, D.; King, R.; Kozubal, A.; Little, C.; Martz, V.; Rothrock, R.; Sutton, J.

    1988-01-01

    The GTA control system provides an environment in which the automation of a state-of-the-art accelerator can be developed. It makes use of commercially available computers, workstations, computer networks, industrial I/O equipment, and software. This system has built-in supervisory control (like most accelerator control systems), tools to support continuous control (like the process control industry), and sequential control for automatic startup and fault recovery (like few other accelerator control systems). Several software tools support these levels of control: a real-time operating system (VxWorks) with a real-time kernel (VRTX), a configuration database, a sequencer, and a graphics editor. VxWorks supports multitasking, fast context-switching, and preemptive scheduling. VxWorks/VRTX is a network-based development environment specifically designed to work in partnership with the UNIX operating system. A database provides the interface to the accelerator components. It consists of a run time library and a database configuration and editing tool. A sequencer initiates and controls the operation of all sequence programs (expressed as state programs). A graphics editor gives the user the ability to create color graphic displays showing the state of the machine in either text or graphics form. 11 refs., 2 figs.

  16. Acceleration of cosmic rays in Tycho's SNR.

    NASA Astrophysics Data System (ADS)

    Morlino, G.; Caprioli, D.

    We apply the non-linear diffusive shock acceleration theory in order to describe the properties of SN 1572 (G120.1+1.4, hereafter simply Tycho). By analyzing its multi-wavelength spectrum, we show how Tycho's forward shock (FS) is accelerating protons up to ˜ 500 TeV, channeling into cosmic rays more than 10 per cent of its kinetic energy. We find that the streaming instability induced by cosmic rays is consistent with all the observational evidences indicating a very efficient magnetic field amplification (up to ˜ 300 mu G), in particular the X-ray morphology of the remnant. We are able to explain the gamma-ray spectrum from the GeV up to the TeV band, recently measured respectively by Fermi-LAT and VERITAS, as due to pion decay produced in nuclear collisions by accelerated nuclei scattering against the background gas. We also show that emission due to the accelerated electrons does not play a relevant role in the observed gamma-ray spectrum.

  17. Consistent Pauli reduction on group manifolds

    NASA Astrophysics Data System (ADS)

    Baguet, A.; Pope, C. N.; Samtleben, H.

    2016-01-01

    We prove an old conjecture by Duff, Nilsson, Pope and Warner asserting that the NSsbnd NS sector of supergravity (and more general the bosonic string) allows for a consistent Pauli reduction on any d-dimensional group manifold G, keeping the full set of gauge bosons of the G × G isometry group of the bi-invariant metric on G. The main tool of the construction is a particular generalised Scherk-Schwarz reduction ansatz in double field theory which we explicitly construct in terms of the group's Killing vectors. Examples include the consistent reduction from ten dimensions on S3 ×S3 and on similar product spaces. The construction is another example of globally geometric non-toroidal compactifications inducing non-geometric fluxes.

  18. Consistency relation for cosmic magnetic fields

    NASA Astrophysics Data System (ADS)

    Jain, Rajeev Kumar; Sloth, Martin S.

    2012-12-01

    If cosmic magnetic fields are indeed produced during inflation, they are likely to be correlated with the scalar metric perturbations that are responsible for the cosmic microwave background anisotropies and large scale structure. Within an archetypical model of inflationary magnetogenesis, we show that there exists a new simple consistency relation for the non-Gaussian cross correlation function of the scalar metric perturbation with two powers of the magnetic field in the squeezed limit where the momentum of the metric perturbation vanishes. We emphasize that such a consistency relation turns out to be extremely useful to test some recent calculations in the literature. Apart from primordial non-Gaussianity induced by the curvature perturbations, such a cross correlation might provide a new observational probe of inflation and can in principle reveal the primordial nature of cosmic magnetic fields.

  19. Self-Consistent Scattering and Transport Calculations

    NASA Astrophysics Data System (ADS)

    Hansen, S. B.; Grabowski, P. E.

    2015-11-01

    An average-atom model with ion correlations provides a compact and complete description of atomic-scale physics in dense, finite-temperature plasmas. The self-consistent ionic and electronic distributions from the model enable calculation of x-ray scattering signals and conductivities for material across a wide range of temperatures and densities. We propose a definition for the bound electronic states that ensures smooth behavior of these measurable properties under pressure ionization and compare the predictions of this model with those of less consistent models for Be, C, Al, and Fe. SNL is a multi-program laboratory managed and operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp, for the U.S. DoE NNSA under contract DE-AC04-94AL85000. This work was supported by DoE OFES Early Career grant FWP-14-017426.

  20. Self-consistency in Capital Markets

    NASA Astrophysics Data System (ADS)

    Benbrahim, Hamid

    2013-03-01

    Capital Markets are considered, at least in theory, information engines whereby traders contribute to price formation with their diverse perspectives. Regardless whether one believes in efficient market theory on not, actions by individual traders influence prices of securities, which in turn influence actions by other traders. This influence is exerted through a number of mechanisms including portfolio balancing, margin maintenance, trend following, and sentiment. As a result market behaviors emerge from a number of mechanisms ranging from self-consistency due to wisdom of the crowds and self-fulfilling prophecies, to more chaotic behavior resulting from dynamics similar to the three body system, namely the interplay between equities, options, and futures. This talk will address questions and findings regarding the search for self-consistency in capital markets.

  1. Observers are consistent when rating image conspicuity.

    PubMed

    Cerf, Moran; Cleary, Daniel R; Peters, Robert J; Einhäuser, Wolfgang; Koch, Christof

    2007-11-01

    Human perception of an image's conspicuity depends on the stimulus itself and the observer's semantic interpretation. We investigated the relative contribution of the former, sensory-driven, component. Participants viewed sequences of images from five different classes-fractals, overhead satellite imagery, grayscale and colored natural scenes, and magazine covers-and graded each numerically according to its perceived conspicuity. We found significant consistency in this rating within and between observers for all image categories. In a subsequent recognition memory test, performance was significantly above chance for all categories, with the weakest memory for satellite imagery, and reaching near ceiling for magazine covers. When repeating the experiment after one year, ratings remained consistent within each observer and category, despite the absence of explicit scene memory. Our findings suggest that the rating of image conspicuity is driven by image-immanent, sensory factors common to all observers.

  2. Consistency Test and Constraint of Quintessence

    SciTech Connect

    Chen, Chien-Wen; Gu, Je-AN; Chen, Pisin; /SLAC /Taiwan, Natl. Taiwan U.

    2012-04-30

    In this paper we highlight our recent work in arXiv:0803.4504. In that work, we proposed a new consistency test of quintessence models for dark energy. Our test gave a simple and direct signature if certain category of quintessence models was not consistent with the observational data. For a category that passed the test, we further constrained its characteristic parameter. Specifically, we found that the exponential potential was ruled out at the 95% confidence level and the power-law potential was ruled out at the 68% confidence level based on the current observational data. We also found that the confidence interval of the index of the power-law potential was between -2 and 0 at the 95% confidence level.

  3. Accelerating the loop expansion

    SciTech Connect

    Ingermanson, R.

    1986-07-29

    This thesis introduces a new non-perturbative technique into quantum field theory. To illustrate the method, I analyze the much-studied phi/sup 4/ theory in two dimensions. As a prelude, I first show that the Hartree approximation is easy to obtain from the calculation of the one-loop effective potential by a simple modification of the propagator that does not affect the perturbative renormalization procedure. A further modification then susggests itself, which has the same nice property, and which automatically yields a convex effective potential. I then show that both of these modifications extend naturally to higher orders in the derivative expansion of the effective action and to higher orders in the loop-expansion. The net effect is to re-sum the perturbation series for the effective action as a systematic ''accelerated'' non-perturbative expansion. Each term in the accelerated expansion corresponds to an infinite number of terms in the original series. Each term can be computed explicitly, albeit numerically. Many numerical graphs of the various approximations to the first two terms in the derivative expansion are given. I discuss the reliability of the results and the problem of spontaneous symmetry-breaking, as well as some potential applications to more interesting field theories. 40 refs.

  4. Laser acceleration in vacuum

    SciTech Connect

    Hsu, J.L.; Katsouleas, T.; Mori, W.B.; Schroeder, C.B.; Wurtele, J.S.

    1997-02-01

    This paper explores the use of the large electric fields of high-brightness lasers (e.g., up to order TV/cm) to accelerate particles. Unfortunately, as is well known, it is difficult to couple the vacuum field of the laser to particles so as to achieve a net energy gain. In principle, the energy gain near the focus of the laser can be quite high, i.e., on the order of the work done in crossing the focus {Delta}{gamma}={radical}({pi})eEw{approximately}30MeV{radical}(P/1TW), where P is the laser power. In order to retain this energy, the particles must be in the highly nonlinear regime (Vosc/c{gt}1) or must be separated from the laser within a distance on the order of a Rayleigh length from the focus. In this work, we explore the acceleration and output energy distribution of an electron beam injected at various angles and injection energies into a focused laser beam. Insight into the physical mechanism of energy gain is obtained by separating the contributions from the longitudinal and transverse laser field components. {copyright} {ital 1997 American Institute of Physics.}

  5. Electron injector for compact staged high energy accelerator

    NASA Astrophysics Data System (ADS)

    Audet, T. L.; Desforges, F. G.; Maitrallain, A.; Dufrénoy, S. Dobosz; Bougeard, M.; Maynard, G.; Lee, P.; Hansson, M.; Aurand, B.; Persson, A.; González, I. Gallardo; Monot, P.; Wahlström, C.-G.; Lundh, O.; Cros, B.

    2016-09-01

    An electron injector for multi-stage laser wakefield experiments is presented. It consists of a variable length gas cell of small longitudinal dimension (⩽ 10 mm). The gas filling process in this cell was characterized both experimentally and with fluid simulation. Electron acceleration experiments were performed at two different laser facilities. Results show low divergence and low pointing fluctuation electron bunches suitable for transport to a second stage, and a peaked energy distribution suitable for injection into the second stage wakefield accelerator.

  6. Neutron emission from fission fragments during acceleration p

    SciTech Connect

    Hinde, D.J.; Charity, R.J.; Foote, G.S.; Leigh, J.R.; Newton, J.O.; Ogaza, S.; Chatterjee, A.

    1984-03-19

    Fission-neutron angular correlations following fusion of /sup 19/F and /sup 232/Th have been measured. Conventional analysis, based on the approximation that post-fission neutrons originate only from fully accelerated fission fragments, gives unexpectedly large numbers of ''prefission'' neutrons. Comparison with the considerably less fissile system /sup 200/Pb gives the first convincing evidence that this approach is inadequate. Consideration of neutron emission from the accelerating fragments gives results consistent with expectations.

  7. Consistency of color representation in smart phones.

    PubMed

    Dain, Stephen J; Kwan, Benjamin; Wong, Leslie

    2016-03-01

    One of the barriers to the construction of consistent computer-based color vision tests has been the variety of monitors and computers. Consistency of color on a variety of screens has necessitated calibration of each setup individually. Color vision examination with a carefully controlled display has, as a consequence, been a laboratory rather than a clinical activity. Inevitably, smart phones have become a vehicle for color vision tests. They have the advantage that the processor and screen are associated and there are fewer models of smart phones than permutations of computers and monitors. Colorimetric consistency of display within a model may be a given. It may extend across models from the same manufacturer but is unlikely to extend between manufacturers especially where technologies vary. In this study, we measured the same set of colors in a JPEG file displayed on 11 samples of each of four models of smart phone (iPhone 4s, iPhone5, Samsung Galaxy S3, and Samsung Galaxy S4) using a Photo Research PR-730. The iPhones are white LED backlit LCD and the Samsung are OLEDs. The color gamut varies between models and comparison with sRGB space shows 61%, 85%, 117%, and 110%, respectively. The iPhones differ markedly from the Samsungs and from one another. This indicates that model-specific color lookup tables will be needed. Within each model, the primaries were quite consistent (despite the age of phone varying within each sample). The worst case in each model was the blue primary; the 95th percentile limits in the v' coordinate were ±0.008 for the iPhone 4 and ±0.004 for the other three models. The u'v' variation in white points was ±0.004 for the iPhone4 and ±0.002 for the others, although the spread of white points between models was u'v'±0.007. The differences are essentially the same for primaries at low luminance. The variation of colors intermediate between the primaries (e.g., red-purple, orange) mirror the variation in the primaries. The variation in

  8. Introduction to Korean Accelerator Science and Activities in Industrial Accelerators

    NASA Astrophysics Data System (ADS)

    Namkung, Won

    2012-03-01

    After 20 years of the first large-scale accelerator in Korea, the Pohang Light Source (PLS) of 2.0 GeV at POSTECH, its upgrade (PLS-II) is now under commissioning with energy of 3.0 GeV. The users' service for synchrotron radiation is scheduled in April 2012. There are five big accelerator projects in various stages of construction, namely a high-intensity proton linac of 100 MeV, the PAL-XFEL of 10-GeV, a carbon therapy cyclotron of 400 MeV/u, and rare isotope accelerators for isotope separator on-line (ISOL) and In-flight Fragmentation (IFF). There are also strong demands for industrial uses of accelerators, especially in sterilization applications. In this paper, we report the current status of accelerator projects and its science in Korea, along with a brief review of accelerator R&D going back to the early 1960s at universities.

  9. Acceleration in Linear and Circular Motion

    ERIC Educational Resources Information Center

    Kellington, S. H.; Docherty, W.

    1975-01-01

    Describes the construction of a simple accelerometer and explains its use in demonstrating acceleration, deceleration, constant speed, measurement of acceleration, acceleration and the inclined plane and angular and radial acceleration. (GS)

  10. 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.

  11. Visual acceleration detection - Effect of sign and motion orientation

    NASA Technical Reports Server (NTRS)

    Calderone, Jack B.; Kaiser, Mary K.

    1989-01-01

    Thresholds for the detection of constant acceleration and deceleration of a discrete object moving along horizontal and vertical axes were studied. A staircase methodology was used to determine thresholds for three average velocities (0.7, 1.2, and 1.7 deg/sec). Thresholds, expressed as the proportion of velocity change, did not differ significantly among the average velocities; thus, a consistent Weber-like fraction is suggested by the data. Furthermore, there was an interaction between the axis of motion (horizontal or vertical) and the sign of the velocity change (acceleration or deceleration): accelerations were easier to detect along the vertical axis, decelerations along the horizontal axis.

  12. Coagulation of Agglomerates Consisting of Polydisperse Primary Particles.

    PubMed

    Goudeli, E; Eggersdorfer, M L; Pratsinis, S E

    2016-09-13

    The ballistic agglomeration of polydisperse particles is investigated by an event-driven (ED) method and compared to the coagulation of spherical particles and agglomerates consisting of monodisperse primary particles (PPs). It is shown for the first time to our knowledge that increasing the width or polydispersity of the PP size distribution initially accelerates the coagulation rate of their agglomerates but delays the attainment of their asymptotic fractal-like structure and self-preserving size distribution (SPSD) without altering them, provided that sufficiently large numbers of PPs are employed. For example, the standard asymptotic mass fractal dimension, Df, of 1.91 is attained when clusters are formed containing, on average, about 15 monodisperse PPs, consistent with fractal theory and the literature. In contrast, when polydisperse PPs with a geometric standard deviation of 3 are employed, about 500 PPs are needed to attain that Df. Even though the same asymptotic Df and mass-mobility exponent, Dfm, are attained regardless of PP polydispersity, the asymptotic prefactors or lacunarities of Df and Dfm increase with PP polydispersity. For monodisperse PPs, the average agglomerate radius of gyration, rg, becomes larger than the mobility radius, rm, when agglomerates consist of more than 15 PPs. Increasing PP polydispersity increases that number of PPs similarly to the above for the attainment of the asymptotic Df or Dfm. The agglomeration kinetics are quantified by the overall collision frequency function. When the SPSD is attained, the collision frequency is independent of PP polydispersity. Accounting for the SPSD polydispersity in the overall agglomerate collision frequency is in good agreement with that frequency from detailed ED simulations once the SPSD is reached. Most importantly, the coagulation of agglomerates is described well by a monodisperse model for agglomerate and PP sizes, whereas the detailed agglomerate size distribution can be obtained by

  13. The concept of coupling impedance in the self-consistent plasma wake field excitation

    NASA Astrophysics Data System (ADS)

    Fedele, R.; Akhter, T.; De Nicola, S.; Migliorati, M.; Marocchino, A.; Massimo, F.; Palumbo, L.

    2016-09-01

    Within the framework of the Vlasov-Maxwell system of equations, we describe the self-consistent interaction of a relativistic charged-particle beam with the surroundings while propagating through a plasma-based acceleration device. This is done in terms of the concept of coupling (longitudinal) impedance in full analogy with the conventional accelerators. It is shown that also here the coupling impedance is a very useful tool for the Nyquist-type stability analysis. Examples of specific physical situations are finally illustrated.

  14. Accelerating an iterative process by explicit annihilation

    NASA Technical Reports Server (NTRS)

    Jespersen, D. C.; Buning, P. G.

    1985-01-01

    A slowly convergent stationary iterative process can be accelerated by explicitly annihilating (i.e., eliminating) the dominant eigenvector component of the error. The dominant eigenvalue or complex pair of eigenvalues can be estimated from the solution during the iteration. The corresponding eigenvector or complex pair of eigenvectors can then be annihilated by applying an explicit Richardson process over the basic iterative method. This can be done entirely in real arithmetic by analytically combining the complex conjugate annihilation steps. The technique is applied to an implicit algorithm for the calculation of two dimensional steady transonic flow over a circular cylinder using the equations of compressible inviscid gas dynamics. This demonstrates the use of explicit annihilation on a nonlinear problem.

  15. Accelerating an iterative process by explicit annihilation

    NASA Technical Reports Server (NTRS)

    Jespersen, D. C.; Buning, P. G.

    1983-01-01

    A slowly convergent stationary iterative process can be accelerated by explicitly annihilating (i.e., eliminating) the dominant eigenvector component of the error. The dominant eigenvalue or complex pair of eigenvalues can be estimated from the solution during the iteration. The corresponding eigenvector or complex pair of eigenvectors can then be annihilated by applying an explicit Richardson process over the basic iterative method. This can be done entirely in real arithmetic by analytically combining the complex conjugate annihilation steps. The technique is applied to an implicit algorithm for the calculation of two dimensional steady transonic flow over a circular cylinder using the equations of compressible inviscid gas dynamics. This demonstrates the use of explicit annihilation on a nonlinear problem.

  16. Techniques to accelerate dynamic psychotherapy.

    PubMed

    Fosha, D; Slowiaczek, M L

    1997-01-01

    The techniques described above outline specific ways to deepen the patient's affective experience within an emotionally close therapeutic relationship. When effective, they all enhance the patient/therapist bond, raise self-esteem, reduce defensiveness and anxiety, and facilitate emotional healing. Psychodynamic treatment, long or short, is a complex process uniquely constructed by each therapist/patient pair. AEDP strategies are not intended as recipes for treatment. Good dynamic work depends on the therapist's ability to grasp the patient's capacities and limitations, understand relational dynamics, and interact with the patient in an empathically attuned, emotionally receptive, and flexible way. In that context, these strategies can be helpful tools to facilitate and accelerate the process. The choices made by AEDP--privileging adaptive strivings over defensive reactions, the stance of emotional engagement rather than neutrality and abstinence, the focus on health and change over pathology and stasis--are informed by traditional STDP aims to maximize depth, effectiveness, and efficiency. AEDP's contribution is a set of techniques relying on a response repertoire that is available to a wide range of therapists. Therapists can use these techniques to be more effective while simultaneously retaining the experience of speaking with patients in an authentic voice.

  17. Lagrangian space consistency relation for large scale structure

    SciTech Connect

    Horn, Bart; Hui, Lam; Xiao, Xiao E-mail: lh399@columbia.edu

    2015-09-01

    Consistency relations, which relate the squeezed limit of an (N+1)-point correlation function to an N-point function, are non-perturbative symmetry statements that hold even if the associated high momentum modes are deep in the nonlinear regime and astrophysically complex. Recently, Kehagias and Riotto and Peloso and Pietroni discovered a consistency relation applicable to large scale structure. We show that this can be recast into a simple physical statement in Lagrangian space: that the squeezed correlation function (suitably normalized) vanishes. This holds regardless of whether the correlation observables are at the same time or not, and regardless of whether multiple-streaming is present. The simplicity of this statement suggests that an analytic understanding of large scale structure in the nonlinear regime may be particularly promising in Lagrangian space.

  18. ENERGY SPECTRUM OF ENERGETIC PARTICLES ACCELERATED BY SHOCK WAVES: FROM FOCUSED TRANSPORT TO DIFFUSIVE ACCELERATION

    SciTech Connect

    Zuo Pingbing; Zhang Ming; Gamayunov, Konstantin; Rassoul, Hamid; Luo Xi

    2011-09-10

    The focused transport equation (FTE) includes all the necessary physics for modeling the shock acceleration of energetic particles with a unified description of first-order Fermi acceleration, shock drift acceleration, and shock surfing acceleration. It can treat the acceleration and transport of particles with an anisotropic distribution. In this study, the energy spectrum of pickup ions accelerated at shocks of various obliquities is investigated based on the FTE. We solve the FTE by using a stochastic approach. The shock acceleration leads to a two-component energy spectrum. The low-energy component of the spectrum is made up of particles that interact with shock one to a few times. For these particles, the pitch angle distribution is highly anisotropic, and the energy spectrum is variable depending on the momentum and pitch angle of injected particles. At high energies, the spectrum approaches a power law consistent with the standard diffusive shock acceleration (DSA) theory. For a parallel shock, the high-energy component of the power-law spectrum, with the spectral index being the same as the prediction of DSA theory, starts just a few times the injection speed. For an oblique or quasi-perpendicular shock, the high-energy component of the spectrum exhibits a double power-law distribution: a harder power-law spectrum followed by another power-law spectrum with a slope the same as the spectral index of DSA. The shock acceleration will eventually go into the DSA regime at higher energies even if the anisotropy is not small. The intensity of the energy spectrum given by the FTE, in the high-energy range where particles get efficient acceleration in the DSA regime, is different from that given by the standard DSA theory for the same injection source. We define the injection efficiency {eta} as the ratio between them. For a parallel shock, the injection efficiency is less than 1, but for an oblique shock or a quasi-perpendicular shock it could be greater.

  19. Evaluating Temporal Consistency in Marine Biodiversity Hotspots

    PubMed Central

    Barner, Allison K.; Benkwitt, Cassandra E.; Boersma, Kate S.; Cerny-Chipman, Elizabeth B.; Ingeman, Kurt E.; Kindinger, Tye L.; Lindsley, Amy J.; Nelson, Jake; Reimer, Jessica N.; Rowe, Jennifer C.; Shen, Chenchen; Thompson, Kevin A.; Heppell, Selina S.

    2015-01-01

    With the ongoing crisis of biodiversity loss and limited resources for conservation, the concept of biodiversity hotspots has been useful in determining conservation priority areas. However, there has been limited research into how temporal variability in biodiversity may influence conservation area prioritization. To address this information gap, we present an approach to evaluate the temporal consistency of biodiversity hotspots in large marine ecosystems. Using a large scale, public monitoring dataset collected over an eight year period off the US Pacific Coast, we developed a methodological approach for avoiding biases associated with hotspot delineation. We aggregated benthic fish species data from research trawls and calculated mean hotspot thresholds for fish species richness and Shannon’s diversity indices over the eight year dataset. We used a spatial frequency distribution method to assign hotspot designations to the grid cells annually. We found no areas containing consistently high biodiversity through the entire study period based on the mean thresholds, and no grid cell was designated as a hotspot for greater than 50% of the time-series. To test if our approach was sensitive to sampling effort and the geographic extent of the survey, we followed a similar routine for the northern region of the survey area. Our finding of low consistency in benthic fish biodiversity hotspots over time was upheld, regardless of biodiversity metric used, whether thresholds were calculated per year or across all years, or the spatial extent for which we calculated thresholds and identified hotspots. Our results suggest that static measures of benthic fish biodiversity off the US West Coast are insufficient for identification of hotspots and that long-term data are required to appropriately identify patterns of high temporal variability in biodiversity for these highly mobile taxa. Given that ecological communities are responding to a changing climate and other

  20. Evaluating Temporal Consistency in Marine Biodiversity Hotspots.

    PubMed

    Piacenza, Susan E; Thurman, Lindsey L; Barner, Allison K; Benkwitt, Cassandra E; Boersma, Kate S; Cerny-Chipman, Elizabeth B; Ingeman, Kurt E; Kindinger, Tye L; Lindsley, Amy J; Nelson, Jake; Reimer, Jessica N; Rowe, Jennifer C; Shen, Chenchen; Thompson, Kevin A; Heppell, Selina S

    2015-01-01

    With the ongoing crisis of biodiversity loss and limited resources for conservation, the concept of biodiversity hotspots has been useful in determining conservation priority areas. However, there has been limited research into how temporal variability in biodiversity may influence conservation area prioritization. To address this information gap, we present an approach to evaluate the temporal consistency of biodiversity hotspots in large marine ecosystems. Using a large scale, public monitoring dataset collected over an eight year period off the US Pacific Coast, we developed a methodological approach for avoiding biases associated with hotspot delineation. We aggregated benthic fish species data from research trawls and calculated mean hotspot thresholds for fish species richness and Shannon's diversity indices over the eight year dataset. We used a spatial frequency distribution method to assign hotspot designations to the grid cells annually. We found no areas containing consistently high biodiversity through the entire study period based on the mean thresholds, and no grid cell was designated as a hotspot for greater than 50% of the time-series. To test if our approach was sensitive to sampling effort and the geographic extent of the survey, we followed a similar routine for the northern region of the survey area. Our finding of low consistency in benthic fish biodiversity hotspots over time was upheld, regardless of biodiversity metric used, whether thresholds were calculated per year or across all years, or the spatial extent for which we calculated thresholds and identified hotspots. Our results suggest that static measures of benthic fish biodiversity off the US West Coast are insufficient for identification of hotspots and that long-term data are required to appropriately identify patterns of high temporal variability in biodiversity for these highly mobile taxa. Given that ecological communities are responding to a changing climate and other