Science.gov

Sample records for 1d relativistic pic

  1. One dimensional PIC simulation of relativistic Buneman instability

    NASA Astrophysics Data System (ADS)

    Rajawat, Roopendra Singh; Sengupta, Sudip

    2016-10-01

    Spatio-temporal evolution of the relativistic Buneman instability has been investigated in one dimension using an in-house developed particle-in-cell simulation code. Starting from the excitation of the instability, its evolution has been followed numerically till its quenching and beyond. The simulation results have been quantitatively compared with the fluid theory and are found to be in conformity with the well known fact that the maximum growth rate (γmax) reduces due to relativistic effects and varies with γ e 0 and m/M as γ m a x ˜ /√{ 3 } 2 √{ γ e 0 } ( /m 2 M ) 1 / 3 , where γ e 0 is the Lorentz factor associated with the initial electron drift velocity (v0) and (m/M) is the electron to ion mass ratio. Further it is observed that in contrast to the non-relativistic results [A. Hirose, Plasma Phys. 20, 481 (1978)] at the saturation point, the ratio of electrostatic field energy density ( ∑ k | E k | 2 / 8 π ) to initial drift kinetic energy density (W0) scales with γ e 0 as ˜ 1 / γe 0 2 . This novel result on the scaling of energy densities has been found to be in quantitative agreement with the scalings derived using fluid theory.

  2. Ion velocity distribution at the termination shock: 1-D PIC simulation

    SciTech Connect

    Lu Quanming; Yang Zhongwei; Lembege, Bertrand

    2012-11-20

    The Voyager 2 (V2) plasma observations of the proton temperature downstream of the quasi-perpendicular heliospheric termination shock (TS) showed that upstream thermal solar wind ions played little role in the shock dissipation mechanism and their downstream temperature is an order of magnitude smaller than predicted by MHD Rankine-Hugoniot conditions. While pickup ions (PUI) are generally expected to play an important role in energy dissipation at the shock, the details remain unclear. Here, one-dimensional (1-D) Particle-in-cell (PIC) code is used to examine kinetic properties and downstream velocity distribution functions of pickup ions (the hot supra-thermal component) and solar wind protons (SWs, the cold component) at the perpendicular heliospheric termination shock. The code treats the pickup ions self-consistently as a third component. Present results show that: (1) both of the incident SWs and PUIs can be separated into two parts: reflected (R) ions and directly transmitted (DT) ions, the energy gain of the R ions at the shock front is much larger than that of the DT ions; (2) the fraction of reflected SWs and their downstream temperature decrease with the relative percentage PUI%; (3) no matter how large the PUI% is, the downstream ion velocity distribution function always can be separated into three parts: 1. a high energy tail (i.e. the wings) dominated by the reflected PUIs, 2. a low energy core mainly contributed by the directly transmitted SWs, and 3. a middle energy part which is a complicated superposition of reflected SWs and directly transmitted PUIs. The significance of the presence of pickup ions on shock front micro-structure and nonstationarity is also discussed.

  3. Ion velocity distribution at the termination shock: 1-D PIC simulation

    NASA Astrophysics Data System (ADS)

    Lu, Quanming; Yang, Zhongwei; Lembège, Bertrand

    2012-11-01

    The Voyager 2 (V2) plasma observations of the proton temperature downstream of the quasi-perpendicular heliospheric termination shock (TS) showed that upstream thermal solar wind ions played little role in the shock dissipation mechanism and their downstream temperature is an order of magnitude smaller than predicted by MHD Rankine-Hugoniot conditions. While pickup ions (PUI) are generally expected to play an important role in energy dissipation at the shock, the details remain unclear. Here, one-dimensional (1-D) Particle-in-cell (PIC) code is used to examine kinetic properties and downstream velocity distribution functions of pickup ions (the hot supra-thermal component) and solar wind protons (SWs, the cold component) at the perpendicular heliospheric termination shock. The code treats the pickup ions self-consistently as a third component. Present results show that: (1) both of the incident SWs and PUIs can be separated into two parts: reflected (R) ions and directly transmitted (DT) ions, the energy gain of the R ions at the shock front is much larger than that of the DT ions; (2) the fraction of reflected SWs and their downstream temperature decrease with the relative percentage PUI%; (3) no matter how large the PUI% is, the downstream ion velocity distribution function always can be separated into three parts: 1. a high energy tail (i.e. the wings) dominated by the reflected PUIs, 2. a low energy core mainly contributed by the directly transmitted SWs, and 3. a middle energy part which is a complicated superposition of reflected SWs and directly transmitted PUIs. The significance of the presence of pickup ions on shock front micro-structure and nonstationarity is also discussed.

  4. Analysis of instability growth and collisionless relaxation in thermionic converters using 1-D PIC simulations

    SciTech Connect

    Kreh, B.B.

    1994-12-01

    This work investigates the role that the beam-plasma instability may play in a thermionic converter. The traditional assumption of collisionally dominated relaxation is questioned, and the beam-plasma instability is proposed as a possible dominant relaxation mechanism. Theory is developed to describe the beam-plasma instability in the cold-plasma approximation, and the theory is tested with two common Particle-in-Cell (PIC) simulation codes. The theory is first confirmed using an unbounded plasma PIC simulation employing periodic boundary conditions, ES1. The theoretically predicted growth rates are on the order of the plasma frequencies, and ES1 simulations verify these predictions within the order of 1%. For typical conditions encountered in thermionic converters, the resulting growth period is on the order of 7 {times} 10{sup {minus}11} seconds. The bounded plasma simulation PDP1 was used to evaluate the influence of finite geometry and the electrode boundaries. For this bounded plasma, a two-stream interaction was supported and resulting in nearly complete thermalization in approximately 5 {times} 10{sup {minus}10} seconds. Since the electron-electron collision rate of 10{sup 9} Hz and the electron atom collision rate of 10{sup 7} Hz are significantly slower than the rate of development of these instabilities, the instabilities appear to be an important relaxation mechanism.

  5. Modeling of the Plasma Electrode Bias in the Negative Ion Sources with 1D PIC Method

    SciTech Connect

    Matsushita, D.; Kuppel, S.; Hatayama, A.; Fukano, A.; Bacal, M.

    2009-03-12

    The effect of the plasma electrode bias voltage in the negative ion sources is modeled and investigated with one-dimensional plasma simulation. A particle-in-cell (PIC) method is applied to simulate the motion of charged particles in their self-consistent electric field. In the simulation, the electron current density is fixed to produce the bias voltage. The tendency of current-voltage characteristics obtained in the simulation show agreement with the one obtained from a simple probe theory. In addition, the H{sup -} ion density peak appears at the bias voltage close to the plasma potential as observed in the experiment. The physical mechanism of this peak H{sup -} ion density is discussed.

  6. PIC EM Relativistic code is used to simulate the Earth bow shock

    NASA Astrophysics Data System (ADS)

    Baraka, S. M.; Ben-Jaffel, L.

    2011-12-01

    The Earth bow shock is created by the supersonic solar wind flowing onto the geomagnetic field. The front of this shock is curved, standing around the Earth from the dayside. The bow shock is of great interest in space plasma investigation as it contains important physics ranging from kinetic to global scales. Interaction of the supersonic solar wind with Earth magnetosphere (magnetopause) creates fast mode magnetosonic waves that travel back upstream, combine and steepen to form the bow shock wave. The distance to the bow shock is then the sum of the magnetopause distance and the magnetosheath thickness. [Merka and Szabo and references therein] It has been established been well established that the bow shock (and the magnetopause) scales with the solar wind ram pressure Psw[Binsack and Vasyliunas, 1968; Formisano, 1979] . We are trying though to simulate the position of the bow shock by using a modified Tristan PIC EM Relativistic Code. By doing so, we will help the science community to use our model to better understand the shock physics in our geospace.

  7. Numerical stability of relativistic beam multidimensional PIC simulations employing the Esirkepov algorithm

    SciTech Connect

    Godfrey, Brendan B.; Vay, Jean-Luc

    2013-09-01

    Rapidly growing numerical instabilities routinely occur in multidimensional particle-in-cell computer simulations of plasma-based particle accelerators, astrophysical phenomena, and relativistic charged particle beams. Reducing instability growth to acceptable levels has necessitated higher resolution grids, high-order field solvers, current filtering, etc. except for certain ratios of the time step to the axial cell size, for which numerical growth rates and saturation levels are reduced substantially. This paper derives and solves the cold beam dispersion relation for numerical instabilities in multidimensional, relativistic, electromagnetic particle-in-cell programs employing either the standard or the Cole–Karkkainnen finite difference field solver on a staggered mesh and the common Esirkepov current-gathering algorithm. Good overall agreement is achieved with previously reported results of the WARP code. In particular, the existence of select time steps for which instabilities are minimized is explained. Additionally, an alternative field interpolation algorithm is proposed for which instabilities are almost completely eliminated for a particular time step in ultra-relativistic simulations.

  8. Implicit relativistic PIC simulations using the four-momentum vector and the electromagnetic four-potential

    NASA Astrophysics Data System (ADS)

    Gourdain, Pierre; Seyler, Charles

    2013-10-01

    New applications in high energy density plasmas and warm dense matter research demand to run long simulations to capture the different characteristic time scales. To keep the actual simulation time reasonable, implicit methods have been developed. Most of them require complex electromagnetic solvers which need to perform exceptionally well on parallel architectures. We can reduce the complexity of such implicit solvers by using the four-potential electromagnetic vector based on Lorenz' gauge instead of the usual electric and magnetic fields representation. As a result, all four potentials follow the second order wave equation. Besides the coding of a single electromagnetic solver valid for all four quantities, the main advantage of this model is the transport of any computational errors to the grid boundary, avoiding error accumulation inside the computational domain. As a particle pusher, we use the particle four-momentum vector instead of the usual momentum. This pusher is a symplectic integrator and conserves exactly the energy of the system. The integration of the implicit electromagnetic solver with the implicit symplectic pusher makes the computation of relativistic plasmas straightforward compared to methods relying directly on electromagnetic fields and conventional particle pushers. Research supported by NNSA/DOE Grant Cooperative Agreements number DE-FC52-06NA 00057, DE-NA 0001836 and NSF Grant # PHY-1102471.

  9. The unusual event of Jan 21st 2005 observed by Cluster spacecracts is considered for comparison by PIC EM Relativistic code simulation

    NASA Astrophysics Data System (ADS)

    Baraka, S. M.; Jaffel, L. B.; Dandouras, I. S.

    2013-12-01

    The unusual event of Jan 21st 2005 observed by Cluster spacecrafts and other space instruments, has been considered for comparison with numerical simulations using a PIC EM Relativistic code for several solar wind plasma conditions. From the comparison using the results obtained so far, we could learn that the main difficulty of the simulation of strong events measured in situ is to properly define/find the undisturbed SW boundary conditions. The second lesson is that it is difficult for the strong and sharp jumps observed in the plasma properties to obtain a clear steady state of the magnetosphere that could be compared instantaneously with in situ measurements. We will show a detailed comparison of the plasma density, velocity components, and magnetic field components along the CL trajectory to the measured in situ data, stressing the added-value of using a PIC code to enrich our diagnostic about very short-term magnetospheric events.

  10. (3+1)D hydrodynamic simulation of relativistic heavy-ion collisions

    SciTech Connect

    Schenke, Bjoern; Jeon, Sangyong; Gale, Charles

    2010-07-15

    We present music, an implementation of the Kurganov-Tadmor algorithm for relativistic 3+1 dimensional fluid dynamics in heavy-ion collision scenarios. This Riemann-solver-free, second-order, high-resolution scheme is characterized by a very small numerical viscosity and its ability to treat shocks and discontinuities very well. We also incorporate a sophisticated algorithm for the determination of the freeze-out surface using a three dimensional triangulation of the hypersurface. Implementing a recent lattice based equation of state, we compute p{sub T}-spectra and pseudorapidity distributions for Au+Au collisions at sq root(s)=200 GeV and present results for the anisotropic flow coefficients v{sub 2} and v{sub 4} as a function of both p{sub T} and pseudorapidity eta. We were able to determine v{sub 4} with high numerical precision, finding that it does not strongly depend on the choice of initial condition or equation of state.

  11. Research on effect of emission uniformity on X-band relativistic backward oscillator using conformal PIC code

    NASA Astrophysics Data System (ADS)

    Chen, Zaigao

    2016-07-01

    Explosive emission cathodes (EECs) are adopted in relativistic backward wave oscillators (RBWOs) to generate intense relativistic electron beam. The emission uniformity of the EEC can render saturation of the power generation unstable and the output mode impure. However, the direct measurement of the plasma parameters on the cathode surface is quite difficult and there are very few related numerical study reports about this issue. In this paper, a self-developed three-dimensional conformal fully electromagnetic particle in cell code is used to study the effect of emission uniformity on the X-band RBWO; the electron explosive emission model and the field emission model are both implemented in the same cathode surface, and the local field enhancement factor is also considered in the field emission model. The RBWO with a random nonuniform EEC is thoroughly studied using this code; the simulation results reveal that when the area ratio of cathode surface for electron explosive emission is 80%, the output power is unstable and the output mode is impure. When the annular EEC does not emit electron in the angle range of 30°, the RBWO can also operate normally.

  12. Research on the effect of cathode plasma expansion on x-band relativistic backward wave oscillator using moving-boundary conformal PIC method

    NASA Astrophysics Data System (ADS)

    Chen, Zaigao; Wang, Jianguo; Wang, Yue

    2016-09-01

    The cathode plasma expansion has been widely investigated and is recognized as impedance collapse in a relativistic backward wave oscillator (RBWO). However, the process of formation and expansion of cathode plasma is very complicated, and the thickness of plasma is only several millimeters, so the simulation of cathode plasma requires high temporal and spatial resolutions. Only the scaled-down diode model and the thin gas layer model are considered in the previous hybrid simulation, and there are few numerical studies on the effect of cathode plasma expansion on the RBWO. In this paper, the moving-boundary conformal particle-in-cell method is proposed; the cathode plasma front is treated in this novel method as the actual cathode surface, and the explosive electron emission boundary moves as the expansion of cathode plasma. Moreover, in order to accurately simulate the electromagnetic field near the cathode surface, the conformal finite-difference time-domain method based on the enlarged cell technique is adopted. The numerical simulation indicates that the diode voltage decreases and the beam current increases as cathode plasma expands; when the cathode plasma velocity is 10 cm/μs, the pulse duration of the generated microwave decreases from 30 ns to 10 ns, the working frequency decreases from 9.83 GHz to 9.64 GHz, and the output power decreases 30% in the course of cathode plasma expansion.

  13. Metadata, PICS and Quality.

    ERIC Educational Resources Information Center

    Armstrong, C. J.

    1997-01-01

    Discusses PICS (Platform for Internet Content Selection), the Centre for Information Quality Management (CIQM), and metadata. Highlights include filtering networked information; the quality of information; and standardizing search engines. (LRW)

  14. [PIC Program Evaluation Forms.

    ERIC Educational Resources Information Center

    Short, N. J.

    These 4 questionnaires are designed to elicit teacher and parent evaluations of the Prescriptive Instruction Center (PIC) program. Included are Teacher Evaluation of Program Effectiveness (14 items), M & M Evaluation of Program Implementation (methods and materials specialists; 11 items), Teacher Evaluation of Program Effectiveness--Case Study…

  15. What Makes a PIC Tick?

    ERIC Educational Resources Information Center

    Montgomery, H. Wynn

    1988-01-01

    The author discusses the establishment and objectives of private industry councils (PICs). Such topics as local decision making, private sector representation, on-site evaluations, and summer jobs programs are covered. Emphasis is on the Atlanta, Georgia PIC. (CH)

  16. Theoretical Investigation of Controlled Generation of a Dense Attosecond Relativistic Electron Bunch from the Interaction of an Ultrashort Laser Pulse with a Nanofilm

    SciTech Connect

    Kulagin, Victor V.; Hur, Min Sup; Suk, Hyyong; Cherepenin, Vladimir A.

    2007-09-21

    For controllable generation of an isolated attosecond relativistic electron bunch [relativistic electron mirror (REM)] with nearly solid-state density, we propose using a solid nanofilm illuminated normally by an ultraintense femtosecond laser pulse having a sharp rising edge. With two-dimensional (2D) particle-in-cell (PIC) simulations, we show that, in spite of Coulomb forces, all of the electrons in the laser spot can be accelerated synchronously, and the REM keeps its surface charge density during evolution. We also developed a self-consistent 1D theory, which takes into account Coulomb forces, radiation of the electrons, and laser amplitude depletion. This theory allows us to predict the REM parameters and shows a good agreement with the 2D PIC simulations.

  17. Loading relativistic Maxwell distributions in particle simulations

    SciTech Connect

    Zenitani, Seiji

    2015-04-15

    Numerical algorithms to load relativistic Maxwell distributions in particle-in-cell (PIC) and Monte-Carlo simulations are presented. For stationary relativistic Maxwellian, the inverse transform method and the Sobol algorithm are reviewed. To boost particles to obtain relativistic shifted-Maxwellian, two rejection methods are proposed in a physically transparent manner. Their acceptance efficiencies are ≈50% for generic cases and 100% for symmetric distributions. They can be combined with arbitrary base algorithms.

  18. Electromagnetic direct implicit PIC simulation

    SciTech Connect

    Langdon, A.B.

    1983-03-29

    Interesting modelling of intense electron flow has been done with implicit particle-in-cell simulation codes. In this report, the direct implicit PIC simulation approach is applied to simulations that include full electromagnetic fields. The resulting algorithm offers advantages relative to moment implicit electromagnetic algorithms and may help in our quest for robust and simpler implicit codes.

  19. PIC Reading Readiness Test Form.

    ERIC Educational Resources Information Center

    Short, N. J.

    This rating form concerns the measurement of basic skills in connection with assessing reading readiness. Motor skills, ability to adjust to learning situations, familiarity with the alphabet, and general knowledge are assessed. See TM 001 111 for details of the Regional PIC program in which it is used. (DLG)

  20. Numerical experiments on unstructured PIC stability.

    SciTech Connect

    Day, David Minot

    2011-04-01

    Particle-In-Cell (PIC) is a method for plasmas simulation. Particles are pushed with Verlet time integration. Fields are modeled using finite differences on a tensor product mesh (cells). The Unstructured PIC methods studied here use instead finite element discretizations on unstructured (simplicial) meshes. PIC is constrained by stability limits (upper bounds) on mesh and time step sizes. Numerical evidence (2D) and analysis will be presented showing that similar bounds constrain unstructured PIC.

  1. PIC Detector for Piano Chords

    NASA Astrophysics Data System (ADS)

    Barbancho, Ana M.; Tardón, Lorenzo J.; Barbancho, Isabel

    2010-12-01

    In this paper, a piano chords detector based on parallel interference cancellation (PIC) is presented. The proposed system makes use of the novel idea of modeling a segment of music as a third generation mobile communications signal, specifically, as a CDMA (Code Division Multiple Access) signal. The proposed model considers each piano note as a CDMA user in which the spreading code is replaced by a representative note pattern. The lack of orthogonality between the note patterns will make necessary to design a specific thresholding matrix to decide whether the PIC outputs correspond to the actual notes composing the chord or not. An additional stage that performs an octave test and a fifth test has been included that improves the error rate in the detection of these intervals that are specially difficult to detect. The proposed system attains very good results in both the detection of the notes that compose a chord and the estimation of the polyphony number.

  2. [Accession to the PIC/S and pharmaceutical quality system in Japan].

    PubMed

    Katori, Noriko

    2014-01-01

    In March, 2012, Japan made the application for membership of the Pharmaceutical Inspection convention and Pharmaceutical Inspection Co-operation scheme (PIC/S) which is an international body of a GMP inspection. The globalization of pharmaceutical manufacturing and sales has been a driving force behind the decision to become a PIC/S member. For the application for membership, Japan's GMP inspectorate needs to fulfill PIC/S requirements, for example, the inspection organization has to have a quality system as a global standard. One of the other requirements is that the GMP inspectorate can access Official Medicines Control Laboratories (OMCL) having high analytical skills and also have a quality system based on ISO 17025. I would like to describe the process to make up a quality system in the National Institute of Health Sciences and also the circumstances around the PIC/S application in Japan.

  3. [Accession to the PIC/S and pharmaceutical quality system in Japan].

    PubMed

    Katori, Noriko

    2014-01-01

    In March, 2012, Japan made the application for membership of the Pharmaceutical Inspection convention and Pharmaceutical Inspection Co-operation scheme (PIC/S) which is an international body of a GMP inspection. The globalization of pharmaceutical manufacturing and sales has been a driving force behind the decision to become a PIC/S member. For the application for membership, Japan's GMP inspectorate needs to fulfill PIC/S requirements, for example, the inspection organization has to have a quality system as a global standard. One of the other requirements is that the GMP inspectorate can access Official Medicines Control Laboratories (OMCL) having high analytical skills and also have a quality system based on ISO 17025. I would like to describe the process to make up a quality system in the National Institute of Health Sciences and also the circumstances around the PIC/S application in Japan. PMID:25707200

  4. Radiation from Relativistic Jets

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the presence of relativistic jets, instabilities such as the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability create collisionless shocks, which are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons in small-scale magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation, a case of diffusive synchrotron radiation, may be important to understand the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  5. WiPics: wireless and beyond.

    PubMed

    Revankar, Ameet V; Gandedkar, Narayan H; Ganeshkar, Sanjay V

    2010-01-01

    A WiPics transmitter allows wireless tranfer of images from the camera to the computer as the photos are being shot. This article describes this novel technological approach and its application in orthodontic imaging. PMID:20122442

  6. Accuracy Analysis of the PIC Method

    NASA Astrophysics Data System (ADS)

    Verboncoeur, J. P.; Cartwright, K. L.

    2000-10-01

    The discretization errors for many steps of the classical Particle-in-Cell (PIC) model have been well-studied (C. K. Birdsall and A. B. Langdon, Plasma Physics via Computer Simulation, McGraw-Hill, New York, NY (1985).) (R. W. Hockney and J. W. Eastwood, Computer Simulation Using Particles, McGraw-Hill, New York, NY (1981).). In this work, the errors in the interpolation algorithms, which provide the connection between continuum particles and discrete fields, are described in greater detail. In addition, the coupling of errors between steps in the method is derived. The analysis is carried out for both electrostatic and electromagnetic PIC models, and the results are demonstrated using a bounded one-dimensional electrostatic PIC code (J. P. Verboncoeur et al., J. Comput. Phys. 104, 321-328 (1993).), as well as a bounded two-dimensional electromagnetic PIC code (J. P. Verboncoeur et al., Comp. Phys. Comm. 87, 199-211 (1995).).

  7. A 2D electrostatic PIC code for the Mark III Hypercube

    SciTech Connect

    Ferraro, R.D.; Liewer, P.C.; Decyk, V.K.

    1990-12-31

    We have implemented a 2D electrostastic plasma particle in cell (PIC) simulation code on the Caltech/JPL Mark IIIfp Hypercube. The code simulates plasma effects by evolving in time the trajectories of thousands to millions of charged particles subject to their self-consistent fields. Each particle`s position and velocity is advanced in time using a leap frog method for integrating Newton`s equations of motion in electric and magnetic fields. The electric field due to these moving charged particles is calculated on a spatial grid at each time by solving Poisson`s equation in Fourier space. These two tasks represent the largest part of the computation. To obtain efficient operation on a distributed memory parallel computer, we are using the General Concurrent PIC (GCPIC) algorithm previously developed for a 1D parallel PIC code.

  8. PIC simulations of SMLWFA for 35fs class lasers

    NASA Astrophysics Data System (ADS)

    Adam, J. C.; Tsung, F. S.; Ren, Chuang; Mori, W. B.; Fonseca, R. A.; Silva, L. O.

    2001-10-01

    In the self-modulated laser wakefield regime a laser pulse several to many 2 π c/ ωp long breaks up via Raman scattering type instabilities producing large wakes. In some cases these wakes can trap background electrons generating a beam of accelerated electrons with a large energy spread. PIC simulations have shown that this process is highly sensitive to the laser intensity, pulse length, and plasma density [K-C.Tzeng et al., PRL 76, 3332 (1996), K-C.Tzeng et al., PRL 79, 5258 (1997)]. There have been some recent experimental results in which 35fs laser pulses have been used. In this case the pulses are at most only a few 2 π c/ ωp long even for the highest densities 10**20 cm-3. We report here on 1D, 2D, and 3D PIC simulations using OSIRIS for parameters closely related to the LULI/LOA results [V.Malka et al., Phys. Plasmas 8, 2605 (2001)].

  9. Electrostatic PIC with adaptive Cartesian mesh

    NASA Astrophysics Data System (ADS)

    Kolobov, Vladimir; Arslanbekov, Robert

    2016-05-01

    We describe an initial implementation of an electrostatic Particle-in-Cell (ES-PIC) module with adaptive Cartesian mesh in our Unified Flow Solver framework. Challenges of PIC method with cell-based adaptive mesh refinement (AMR) are related to a decrease of the particle-per-cell number in the refined cells with a corresponding increase of the numerical noise. The developed ES-PIC solver is validated for capacitively coupled plasma, its AMR capabilities are demonstrated for simulations of streamer development during high-pressure gas breakdown. It is shown that cell-based AMR provides a convenient particle management algorithm for exponential multiplications of electrons and ions in the ionization events.

  10. 2D PIC simulations for an EN discharge with magnetized electrons and unmagnetized ions

    NASA Astrophysics Data System (ADS)

    Lieberman, Michael A.; Kawamura, Emi; Lichtenberg, Allan J.

    2009-10-01

    We conducted 2D particle-in-cell (PIC) simulations for an electronegative (EN) discharge with magnetized electrons and unmagnetized ions, and compared the results to a previously developed 1D (radial) analytical model of an EN plasma with strongly magnetized electrons and weakly magnetized ions [1]. In both cases, there is a static uniform applied magnetic field in the axial direction. The 1D radial model mimics the wall losses of the particles in the axial direction by introducing a bulk loss frequency term νL. A special (desired) solution was found in which only positive and negative ions but no electrons escaped radially. The 2D PIC results show good agreement with the 1D model over a range of parameters and indicate that the analytical form of νL employed in [1] is reasonably accurate. However, for the PIC simulations, there is always a finite flux of electrons to the radial wall which is about 10 to 30% of the negative ion flux.[4pt] [1] G. Leray, P. Chabert, A.J. Lichtenberg and M.A. Lieberman, J. Phys. D, accepted for publication 2009.

  11. 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.

  12. 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.

  13. Mars' 1995 opposition from PIC du Midi

    NASA Astrophysics Data System (ADS)

    Erard, S.

    1997-03-01

    The last Martian apparition was observed from Pic du Midi between October 1994 and March 1995. Earth-based observation remains the only practicable way to perform continuous surveys of the planets, as opposed to orbital (HST) or space-borne observation. A good planetary site with limited demand for observational time like the 1-m telescope at Pic du Midi provides the optimal opportunity to monitor planetary activity, including atmospheric phenomena, surface variations, and polar caps recession. For instance, HST observations of Mars during this period, though yielding a much better spatial resolution, are limited to very few sessions and do not make it possible to monitor quick processes along a whole Martian season.

  14. PIC Simulation Models of Hypersonic Plasma

    NASA Astrophysics Data System (ADS)

    Niehoff, Dustin; Ashour-Abdalla, Maha; Niemann, Chris; Decyk, Viktor; Schriver, David; Clark, S. Eric; Sotnikov, Vladimir

    2013-10-01

    The plasma sheaths formed around hypersonic aircraft (Mach number over 10) are relatively unexplored and of interest today to both further the development of new technologies and solve long-standing engineering problems. PIC simulations are necessary when phenomena are expected to be observed below typical ion scales; however, if the scales of the problem are not significantly below this, then the initialization of the PIC simulation must be very carefully engineered to avoid unnecessary computation while still retaining structures of interest. In order to avoid excess computational expense, we use a radial density profile from hybrid simulation results to seed the distribution of a self-consistent PIC simulation in one direction, transverse to an external magnetic field. To further reduce the expense, we also use a Darwin approximation which neglects retardation, but effects from lower frequency modes are unchanged, allowing us to feasibly simulate over the required distances and durations. The simulation will be run in two spatial dimensions but retain three velocity dimensions, and the results will be used to explore the growth of micro-instabilities present in hypersonic plasmas in the high-density region as it moves through the simulation box. Work supported by the AFRL.

  15. Modeling Laser Wake Field Acceleration with the Quasi-Static PIC Code QuickPIC

    SciTech Connect

    Vieira, J.; Antonsen, T. Jr.; Cooley, J.; Silva, L. O.

    2006-11-27

    We use the Quasi-static Particle-In-Cell code QuickPIC to model laser wake field acceleration, in both uniform and parabolic plasma channels within current state of the art experimental laser and plasma parameters. QuickPIC uses the quasi-static approximation, which allows the separation of the plasma and laser evolution, as they respond in different time scales. The laser is evolved with a larger time step, that correctly resolves distances of the order of the Rayleigh length, according to the ponderomotive guiding center approximation, while the plasma response is calculated through a quasi-static field solver for each transverse 2d slice. We have performed simulations that show very good agreement between QuickPIC and three dimensional simulations using the full PIC code OSIRIS. We have scanned laser intensities from those for which linear plasma waves are excited to those for which the plasma response is highly nonlinear. For these simulations, QuickPIC was 2-3 orders of magnitude faster than OSIRIS.

  16. Hybrid-PIC Simulations of Shock Formation in Laser-Irradiated Plasmas

    NASA Astrophysics Data System (ADS)

    Tableman, Adam; Tzoufras, M.; Fiuza, F.; Mori, W. B.

    2013-10-01

    Shock generation by hot electron beams (with intensities ranging from 1014 W/cm2 to 1016 W/cm2) impinging on high density targets (1024 /cm3) is investigated using a 1D hybrid-PIC version of OSIRIS. The hybrid-PIC code uses a fluid model to follow electron transport at high densities. In these simulations an electron cathode is used as a proxy for hot electrons generated in under-dense regions by laser-plasma interactions. This approach enables control over the composition and energy distribution of the hot electrons entering the high density region, which, in turn, allows the direct study of hot electron energy deposition and the corresponding shock structure. Understanding how to harness the hot electrons to enhance shock formation will aid in designing Shock Ignition ICF targets with improved yield. Support by the DOE under Fusion Science Center through a University of Rochester Subcontract No. 415025-G.

  17. A multi-dimensional nonlinearly implicit, electromagnetic Vlasov-Darwin particle-in-cell (PIC) algorithm

    NASA Astrophysics Data System (ADS)

    Chen, Guangye; Chacón, Luis; CoCoMans Team

    2014-10-01

    For decades, the Vlasov-Darwin model has been recognized to be attractive for PIC simulations (to avoid radiative noise issues) in non-radiative electromagnetic regimes. However, the Darwin model results in elliptic field equations that renders explicit time integration unconditionally unstable. Improving on linearly implicit schemes, fully implicit PIC algorithms for both electrostatic and electromagnetic regimes, with exact discrete energy and charge conservation properties, have been recently developed in 1D. This study builds on these recent algorithms to develop an implicit, orbit-averaged, time-space-centered finite difference scheme for the particle-field equations in multiple dimensions. The algorithm conserves energy, charge, and canonical-momentum exactly, even with grid packing. A simple fluid preconditioner allows efficient use of large timesteps, O (√{mi/me}c/veT) larger than the explicit CFL. We demonstrate the accuracy and efficiency properties of the of the algorithm with various numerical experiments in 2D3V.

  18. Asymmetric modes decomposition in an overmoded relativistic backward wave oscillator

    SciTech Connect

    Zhang, Dian; Zhang, Jun Zhong, Huihuang; Jin, Zhenxing; Ju, Jinchuan

    2014-09-15

    Most of the investigated overmoded relativistic backward wave oscillators (RBWOs) are azimuthally symmetric; thus, they are designed through two dimensional (2-D) particle-in-cell (PIC) simulations. However, 2-D PIC simulations cannot reveal the effect of asymmetric modes on beam-wave interaction. In order to investigate whether asymmetric mode competition needs to be considered in the design of overmoded RBWOs, a numerical method of determining the composition of both symmetric and asymmetric modes in three dimensional (3-D) PIC simulations is introduced in this paper. The 2-D and 3-D PIC simulation results of an X-band overmoded RBWO are analyzed. Our analysis indicates that the 2-D and 3-D PIC simulation results of our device are quite different due to asymmetric mode competition. In fact, asymmetric surface waves, especially EH{sub 11} mode, can lead to serious mode competition when electron beam propagates near the surface of slow wave structures (SWSs). Therefore, additional method of suppressing asymmetric mode competition, such as adjusting the reflections at both ends of SWSs to decrease the Q-factor of asymmetric modes, needs to be utilized in the design of overmoded RBWOs. Besides, 3-D PIC simulation and modes decomposition are essential for designing overmoded RBWOs.

  19. Relativistic diffusion

    NASA Astrophysics Data System (ADS)

    Haba, Z.

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

  20. Relativistic diffusion.

    PubMed

    Haba, Z

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

  1. The Pic du Midi solar survey

    NASA Astrophysics Data System (ADS)

    Koechlin, L.

    2015-12-01

    We carry a long term survey of the solar activity with our coronagraphic system at Pic du Midi de Bigorre in the French Pyrenees (CLIMSO). It is a set of two solar telescopes and two coronagraphs, taking one frame per minute for each of the four channels : Solar disk in H-α (656.28 nm), prominences in H-α, disk in Ca II (393.3 nm), prominences in He I (1083 nm), all year long, weather permitting. Since 2015 we also take images of the FeXIII corona (1074.7 nm) at the rate of one every 10 minutes. These images cover a large field: 1.25 solar diameter, 2k*2K pixels, and are freely downloadable form a database. The improvements made since 2015 concern an autoguiding system for better centering of the solar disk behind the coronagraphic masks, and a new Fe XIII channel at λ=1074.7 nm. In the near future we plan to provide radial velocity maps of the disc and polarimetry maps of the disk and corona. This survey took its present form in 2007 and we plan to maintain image acquisition in the same or better experimental conditions for a long period: one or several solar cycles if possible. During the partial solar eclipse of March 20, 2015, the CLIMSO instruments and the staff at Pic du Midi operating it have provided several millions internet users with real time images of the Sun and Moon during all the phenomenon.

  2. A curvilinear, fully implicit, conservative electromagnetic PIC algorithm in multiple dimensions

    DOE PAGES

    Chacon, L.; Chen, G.

    2016-04-19

    Here, we extend a recently proposed fully implicit PIC algorithm for the Vlasov–Darwin model in multiple dimensions (Chen and Chacón (2015) [1]) to curvilinear geometry. As in the Cartesian case, the approach is based on a potential formulation (Φ, A), and overcomes many difficulties of traditional semi-implicit Darwin PIC algorithms. Conservation theorems for local charge and global energy are derived in curvilinear representation, and then enforced discretely by a careful choice of the discretization of field and particle equations. Additionally, the algorithm conserves canonical-momentum in any ignorable direction, and preserves the Coulomb gauge ∇ • A = 0 exactly. Anmore » asymptotically well-posed fluid preconditioner allows efficient use of large cell sizes, which are determined by accuracy considerations, not stability, and can be orders of magnitude larger than required in a standard explicit electromagnetic PIC simulation. We demonstrate the accuracy and efficiency properties of the algorithm with numerical experiments in mapped meshes in 1D-3V and 2D-3V.« less

  3. A curvilinear, fully implicit, conservative electromagnetic PIC algorithm in multiple dimensions

    NASA Astrophysics Data System (ADS)

    Chacón, L.; Chen, G.

    2016-07-01

    We extend a recently proposed fully implicit PIC algorithm for the Vlasov-Darwin model in multiple dimensions (Chen and Chacón (2015) [1]) to curvilinear geometry. As in the Cartesian case, the approach is based on a potential formulation (ϕ, A), and overcomes many difficulties of traditional semi-implicit Darwin PIC algorithms. Conservation theorems for local charge and global energy are derived in curvilinear representation, and then enforced discretely by a careful choice of the discretization of field and particle equations. Additionally, the algorithm conserves canonical-momentum in any ignorable direction, and preserves the Coulomb gauge ∇ ṡ A = 0 exactly. An asymptotically well-posed fluid preconditioner allows efficient use of large cell sizes, which are determined by accuracy considerations, not stability, and can be orders of magnitude larger than required in a standard explicit electromagnetic PIC simulation. We demonstrate the accuracy and efficiency properties of the algorithm with numerical experiments in mapped meshes in 1D-3V and 2D-3V.

  4. Relativistic geodesy

    NASA Astrophysics Data System (ADS)

    Flury, J.

    2016-06-01

    Quantum metrology enables new applications in geodesy, including relativistic geodesy. The recent progress in optical atomic clocks and in long-distance frequency transfer by optical fiber together pave the way for using measurements of the gravitational frequency redshift for geodesy. The remote comparison of frequencies generated by calibrated clocks will allow for a purely relativistic determination of differences in gravitational potential and height between stations on Earth surface (chronometric leveling). The long-term perspective is to tie potential and height differences to atomic standards in order to overcome the weaknesses and inhomogeneity of height systems determined by classical spirit leveling. Complementarily, gravity measurements with atom interferometric setups, and satellite gravimetry with space borne laser interferometers allow for new sensitivities in the measurement of the Earth's gravity field.

  5. Relativistic klystrons

    SciTech Connect

    Allen, M.A.; Azuma, O.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Hoag, H.A.; Koontz, R.F.

    1989-03-01

    Experimental work is underway by a SLAC-LLNL-LBL collaboration to investigate the feasibility of using relativistic klystrons as a power source for future high gradient accelerators. Two different relativistic klystron configurations have been built and tested to date: a high grain multicavity klystron at 11.4 GHz and a low gain two cavity subharmonic buncher driven at 5.7 GHz. In both configurations power is extracted at 11.4 GHz. In order to understand the basic physics issues involved in extracting RF from a high power beam, we have used both a single resonant cavity and a multi-cell traveling wave structure for energy extraction. We have learned how to overcome our previously reported problem of high power RF pulse shortening, and have achieved peak RF power levels of 170 MW with the RF pulse of the same duration as the beam current pulse. 6 refs., 3 figs., 3 tabs.

  6. Relativistic Astrophysics

    NASA Astrophysics Data System (ADS)

    Jones, Bernard J. T.; Markovic, Dragoljub

    1997-06-01

    Preface; Prologue: Conference overview Bernard Carr; Part I. The Universe At Large and Very Large Redshifts: 2. The size and age of the Universe Gustav A. Tammann; 3. Active galaxies at large redshifts Malcolm S. Longair; 4. Observational cosmology with the cosmic microwave background George F. Smoot; 5. Future prospects in measuring the CMB power spectrum Philip M. Lubin; 6. Inflationary cosmology Michael S. Turner; 7. The signature of the Universe Bernard J. T. Jones; 8. Theory of large-scale structure Sergei F. Shandarin; 9. The origin of matter in the universe Lev A. Kofman; 10. New guises for cold-dark matter suspects Edward W. Kolb; Part II. Physics and Astrophysics Of Relativistic Compact Objects: 11. On the unification of gravitational and inertial forces Donald Lynden-Bell; 12. Internal structure of astrophysical black holes Werner Israel; 13. Black hole entropy: external facade and internal reality Valery Frolov; 14. Accretion disks around black holes Marek A. Abramowicz; 15. Black hole X-ray transients J. Craig Wheeler; 16. X-rays and gamma rays from active galactic nuclei Roland Svensson; 17. Gamma-ray bursts: a challenge to relativistic astrophysics Martin Rees; 18. Probing black holes and other exotic objects with gravitational waves Kip Thorne; Epilogue: the past and future of relativistic astrophysics Igor D. Novikov; I. D. Novikov's scientific papers and books.

  7. It's about Time: The Literacy TopPics Awards.

    ERIC Educational Resources Information Center

    And Others; Swafford, Jeanne

    1997-01-01

    Examines the last five years of articles in this journal to show what topics were most often written about (the "Top Picks" or "TopPics"). Discusses these results and makes recommendations that deserve considerable attention in the future. Notes that integrated language arts was a perennial TopPic. (SR)

  8. PIC Simulations of Hypersonic Plasma Instabilities

    NASA Astrophysics Data System (ADS)

    Niehoff, D.; Ashour-Abdalla, M.; Niemann, C.; Decyk, V.; Schriver, D.; Clark, E.

    2013-12-01

    The plasma sheaths formed around hypersonic aircraft (Mach number, M > 10) are relatively unexplored and of interest today to both further the development of new technologies and solve long-standing engineering problems. Both laboratory experiments and analytical/numerical modeling are required to advance the understanding of these systems; it is advantageous to perform these tasks in tandem. There has already been some work done to study these plasmas by experiments that create a rapidly expanding plasma through ablation of a target with a laser. In combination with a preformed magnetic field, this configuration leads to a magnetic "bubble" formed behind the front as particles travel at about Mach 30 away from the target. Furthermore, the experiment was able to show the generation of fast electrons which could be due to instabilities on electron scales. To explore this, future experiments will have more accurate diagnostics capable of observing time- and length-scales below typical ion scales, but simulations are a useful tool to explore these plasma conditions theoretically. Particle in Cell (PIC) simulations are necessary when phenomena are expected to be observed at these scales, and also have the advantage of being fully kinetic with no fluid approximations. However, if the scales of the problem are not significantly below the ion scales, then the initialization of the PIC simulation must be very carefully engineered to avoid unnecessary computation and to select the minimum window where structures of interest can be studied. One method of doing this is to seed the simulation with either experiment or ion-scale simulation results. Previous experiments suggest that a useful configuration for studying hypersonic plasma configurations is a ring of particles rapidly expanding transverse to an external magnetic field, which has been simulated on the ion scale with an ion-hybrid code. This suggests that the PIC simulation should have an equivalent configuration

  9. Nonlinear PIC simulation in a Penning trap

    NASA Astrophysics Data System (ADS)

    Lapenta, G.; Delzanno, G. L.; Finn, J. M.

    2002-01-01

    We study the nonlinear dynamics of a Penning trap plasma, including the effect of the finite length and end curvature of the plasma column. A new cylindrical PIC code, called KANDINSKY, has been implemented by using a new interpolation scheme. The principal idea is to calculate the volume of each cell from a particle volume, in the same manner as it is done for the cell charge. With this new method, the density is conserved along streamlines and artificial sources of compressibility are avoided. The code has been validated with a reference Eulerian fluid code. We compare the dynamics of three different models: a model with compression effects, the standard Euler model and a geophysical fluid dynamics model. The results of our investigation prove that Penning traps can really be used to simulate geophysical fluids.

  10. A study of dc discharge in cylindrical magnetron - comparison of experiment and PIC model

    NASA Astrophysics Data System (ADS)

    Behnke, J. F.; Csambal, C.; Tichy, M.; Kudrna, P.; Rusz, J.

    2000-10-01

    We present experimental and numerical study of the DC discharge in cylindrical magnetron in argon. The grounded discharge chamber-anode has 110 mm in length and 60 mm inner diameter. The co-axially placed cathode has 10 mm in diameter. The magnetic field is created by couple of coils. Experimental results have been obtained by radially movable planar Langmuir probe with its plane perpendicular to the magnetic field lines. The radial profiles of the floating and plasma potential, plasma density, and the electron energy distribution function have been measured. Numerical results were obtained using the modified 1D PIC code (Berkeley). The comparison between experiment and model results computed at similar conditions shows reasonable agreement in plasma density and electron mean energy. The computed electric field is usually higher than the experimental one. This difference we explain by the end effects that are not taken into account in 1D model.

  11. Numerical stability analysis of the pseudo-spectral analytical time-domain PIC algorithm

    SciTech Connect

    Godfrey, Brendan B.; Vay, Jean-Luc; Haber, Irving

    2014-02-01

    The pseudo-spectral analytical time-domain (PSATD) particle-in-cell (PIC) algorithm solves the vacuum Maxwell's equations exactly, has no Courant time-step limit (as conventionally defined), and offers substantial flexibility in plasma and particle beam simulations. It is, however, not free of the usual numerical instabilities, including the numerical Cherenkov instability, when applied to relativistic beam simulations. This paper derives and solves the numerical dispersion relation for the PSATD algorithm and compares the results with corresponding behavior of the more conventional pseudo-spectral time-domain (PSTD) and finite difference time-domain (FDTD) algorithms. In general, PSATD offers superior stability properties over a reasonable range of time steps. More importantly, one version of the PSATD algorithm, when combined with digital filtering, is almost completely free of the numerical Cherenkov instability for time steps (scaled to the speed of light) comparable to or smaller than the axial cell size.

  12. Development and Test of 2.5-Dimensional Electromagnetic PIC Simulation Code

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Yun; Lee, Ensang; Kim, Khan-Hyuk; Seon, Jongho; Lee, Dong-Hun; Ryu, Kwang-Sun

    2015-03-01

    We have developed a 2.5-dimensional electromagnetic particle simulation code using the particle-in-cell (PIC) method to investigate electromagnetic phenomena that occur in space plasmas. Our code is based on the leap-frog method and the centered difference method for integration and differentiation of the governing equations. We adopted the relativistic Buneman-Boris method to solve the Lorentz force equation and the Esirkepov method to calculate the current density while maintaining charge conservation. Using the developed code, we performed test simulations for electron two-stream instability and electron temperature anisotropy induced instability with the same initial parameters as used in previously reported studies. The test simulation results are almost identical with those of the previous papers.

  13. Generalized SIMD algorithm for efficient EM-PIC simulations on modern CPUs

    NASA Astrophysics Data System (ADS)

    Fonseca, Ricardo; Decyk, Viktor; Mori, Warren; Silva, Luis

    2012-10-01

    There are several relevant plasma physics scenarios where highly nonlinear and kinetic processes dominate. Further understanding of these scenarios is generally explored through relativistic particle-in-cell codes such as OSIRIS [1], but this algorithm is computationally intensive, and efficient use high end parallel HPC systems, exploring all levels of parallelism available, is required. In particular, most modern CPUs include a single-instruction-multiple-data (SIMD) vector unit that can significantly speed up the calculations. In this work we present a generalized PIC-SIMD algorithm that is shown to work efficiently with different CPU (AMD, Intel, IBM) and vector unit types (2-8 way, single/double). Details on the algorithm will be given, including the vectorization strategy and memory access. We will also present performance results for the various hardware variants analyzed, focusing on floating point efficiency. Finally, we will discuss the applicability of this type of algorithm for EM-PIC simulations on GPGPU architectures [2]. [4pt] [1] R. A. Fonseca et al., LNCS 2331, 342, (2002)[0pt] [2] V. K. Decyk, T. V. Singh; Comput. Phys. Commun. 182, 641-648 (2011)

  14. A revision of the genus Macrolygistopterus Pic, 1929 (Coleoptera, Lycidae, Calochromini).

    PubMed

    Ferreira, Vinicius S

    2016-04-21

    A taxonomic review of the Lycid genus Macrolygistopterus Pic, 1929 with illustrations of diagnostic characters, geographic distribution maps and an identification key to the species is presented. Also, a key to the world Calochromini is given. Of the 12 species of the genus, 9 were studied: M. succinctus (Latreille, 1811), M. quadricostatus (Buquet, 1842), M. caeruleus (Gorham, 1884), M. germaini Pic, 1930, M. grandjeani Pic, 1930, M. subparallelus Pic, 1930, M. testaceirostris Pic, 1930, M. simoni Pic, 1930 and M. kirschi Pic, 1931 were redescribed and their status as valid species is confirmed. The lectotypes and paralectotypes were designated for all those examined species. M. bilineatus (Pic, 1923), M. diversicornis Pic, 1930 and M. bipartitus Pic, 1933 remain as valid species since these specimens were not available for this study. M. succinctus var. scutelaris Pic, 1930 is proposed here as new junior synonym of M. succinctus (Latreille, 1811).

  15. 3D PIC Modeling of Microcavity Discharge

    NASA Astrophysics Data System (ADS)

    Hopkins, Matthew; Manginell, Ronald; Moore, Christopher; Yee, Benjamin; Moorman, Matthew

    2015-09-01

    We present a number of techniques and challenges in simulating the transient behavior of a microcavity discharge. Our microcavities are typically cylindrical with diameters approximately 50 - 100 μm, heights of 50 - 200 μm, pressure near atmospheric, and operate at a few hundred volts. We employ a fully kinetic simulation methodology, the Particle-in-Cell (PIC) method, with interparticle collisions handled via methods based on direct simulation Monte Carlo (DSMC). In particular, we explicitly include kinetic electrons. Some of the challenges we encounter include variations in number densities, external circuit coupling, and time step resolution constraints. By employing dynamic particle weighting (particle weights vary over time by species and location) we can mitigate some of the challenges modeling systems with 107 variations in number densities. Smoothing mechanisms have been used to attempt to mitigate external circuit response. We perform our simulations on hundreds or thousands of processing cores to accommodate the computational work inherent in using relatively small time step sizes (e.g., 50 fs for a 100 ns calculation). In addition, particle weighting issues inherent to three-dimensional low temperature plasma systems will be mentioned. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under Contract DE-AC04-94AL85000.

  16. Relativistic tearing and drift-kink instabilities in two-fluid simulations

    NASA Astrophysics Data System (ADS)

    Barkov, Maxim V.; Komissarov, Serguei S.

    2016-05-01

    The stability of current sheets in collisionless relativistic pair plasma was studied via two-dimensional two-fluid relativistic magnetohydrodynamic simulations with vanishing internal friction between fluids. In particular, we investigated the linear growth of the tearing and drift-kink modes in the current sheets both with and without the guide field and obtained the growth rates which are very similar to what has been found in the corresponding particle in cell (PIC) simulations. This suggests that the two-fluid simulations can be useful in studying the large-scale dynamics of astrophysical relativistic plasmas in problems involving magnetic reconnection.

  17. Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P.; Hededal, C.; Mizuno, Yosuke; Fishman, G. Jerry; Hartmann, D. H.

    2006-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), supernova remnants, 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. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that particle acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration' is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different spectral properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations of relativistic jets and try to make a connection with observations.

  18. Relativistic fluid dynamics. Proceedings.

    NASA Astrophysics Data System (ADS)

    Anile, A. M.; Choquet-Bruhat, Y.

    Contents: 1. Covariant theory of conductivity in ideal fluid or solid media (B. Carter). 2. Hamiltonian techniques for relativistic fluid dynamics and stability theory (D. D. Holm). 3. Covariant fluid mechanics and thermodynamics: an introduction (W. Israel). 4. Relativistic plasmas (H. Weitzner). 5. An improved relativistic warm plasma model (A. M. Anile, S. Pennisi). 6. Relativistic extended thermodynamics II (I. Müller). 7. Relativistic extended thermodynamics: general assumptions and mathematical procedure (T. Ruggeri). 8. Relativistic hydrodynamics and heavy ion reactions (D. Strottman). 9. Some problems in relativistic hydrodynamics (C. G. van Weert).

  19. Nonlinear PIC Simulations for Nonneutral Plasmas

    NASA Astrophysics Data System (ADS)

    Lapenta, Giovanni; Luca Delzanno, Gian; Finn, John M.

    2002-11-01

    We present nonlinear simulations of the low frequency dynamics of electrons in a Malmberg-Penning trap, including compressional and thermal effects [1,2]. First, we consider a 2D model where we assume the effective plasma length constant in time. In this framework, we further neglect the thermal effect on the velocity field, and show with the PIC code KANDINSKY that Penning traps could be used to perform geophysical fluid dynamics experiments [3]. We also observe that, due to the presence of the nonlinear m=1 instability, the initially hollow density profile becomes peaked, as in the experiments. Then, we show 2D results including thermal effects. In this case, the development of the m=1 instability is slowed since the equilibrium plasma length profile is closer to the integrable profile, namely the length profile for which there are no discrete unstable modes [4]. Finally, we present simulations of the 3D fluiddynamics model of Ref. [2]. In particular, we investigate the evolution of a m=1 perturbation for different electron temperatures, when compressional and thermal effects are included. [1] J.M. Finn, D. del-Castillo-Negrete, D.C. Barnes,Phys. Plasmas, 6, 3744, 1999. [2] G.G.M. Coppa, A. D'Angola, G.L. Delzanno, G. Lapenta, Phys. Plasmas, 8, 1133, 2001. [3] G.L. Delzanno, J.M. Finn, G. Lapenta, "Nonlinear Phase of the Compressional m=1 Diocotron Instability: Saturation and Analogy with Geophysical Fluid Dynamics", submitted to Phys. Plasmas. [4] G.L. Delzanno, V.I. Pariev, J.M. Finn, G. Lapenta, "Stability Analysis of Hollow Electron Columns Including Compression and Thermal Effects: Integrability Condition and Numerical Simulations", submitted to Phys. Plasmas.

  20. Adaptive wavelets and relativistic magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Hirschmann, Eric; Neilsen, David; Anderson, Matthe; Debuhr, Jackson; Zhang, Bo

    2016-03-01

    We present a method for integrating the relativistic magnetohydrodynamics equations using iterated interpolating wavelets. Such provide an adaptive implementation for simulations in multidimensions. A measure of the local approximation error for the solution is provided by the wavelet coefficients. They place collocation points in locations naturally adapted to the flow while providing expected conservation. We present demanding 1D and 2D tests includingthe Kelvin-Helmholtz instability and the Rayleigh-Taylor instability. Finally, we consider an outgoing blast wave that models a GRB outflow.

  1. Playing relativistic billiards beyond graphene

    NASA Astrophysics Data System (ADS)

    Sadurní, E.; Seligman, T. H.; Mortessagne, F.

    2010-05-01

    The possibility of using hexagonal structures in general, and graphene in particular, to emulate the Dirac equation is the topic under consideration here. We show that Dirac oscillators with or without rest mass can be emulated by distorting a tight-binding model on a hexagonal structure. In the quest to make a toy model for such relativistic equations, we first show that a hexagonal lattice of attractive potential wells would be a good candidate. Firstly, we consider the corresponding one-dimensional (1D) model giving rise to a 1D Dirac oscillator and then construct explicitly the deformations needed in the 2D case. Finally, we discuss how such a model can be implemented as an electromagnetic billiard using arrays of dielectric resonators between two conducting plates that ensure evanescent modes outside the resonators for transversal electric modes, and we describe a feasible experimental setup.

  2. Energy loss and longitudinal wakefield of relativistic short proton bunches in electron clouds

    NASA Astrophysics Data System (ADS)

    Boine-Frankenheim, O.; Gjonaj, E.; Petrov, F.; Yaman, F.; Weiland, T.; Rumolo, G.

    2012-05-01

    The aim of our study is the numerical computation of the wakefield and energy loss per unit length for relativistic, short (<10ns) proton bunches interacting with an electron cloud inside the beam pipe. We present analytical expressions for the energy loss in the impulse kick approximation. For the simulation of the wakefields a 2D self-consistent, electrostatic particle-in-cell (PIC) code is employed. Results for the energy loss and for the wakefields are presented for the parameter scope of the CERN LHC and SPS. For selected parameters the results are compared to a three-dimensional (3D) electromagnetic PIC code.

  3. Relativistic Shocks: Particle Acceleration and Magnetization

    NASA Astrophysics Data System (ADS)

    Sironi, L.; Keshet, U.; Lemoine, M.

    2015-10-01

    We review the physics of relativistic shocks, which are often invoked as the sources of non-thermal particles in pulsar wind nebulae (PWNe), gamma-ray bursts (GRBs), and active galactic nuclei (AGN) jets, and as possible sources of ultra-high energy cosmic-rays. We focus on particle acceleration and magnetic field generation, and describe the recent progress in the field driven by theory advances and by the rapid development of particle-in-cell (PIC) simulations. In weakly magnetized or quasi parallel-shocks (i.e. where the magnetic field is nearly aligned with the flow), particle acceleration is efficient. The accelerated particles stream ahead of the shock, where they generate strong magnetic waves which in turn scatter the particles back and forth across the shock, mediating their acceleration. In contrast, in strongly magnetized quasi-perpendicular shocks, the efficiencies of both particle acceleration and magnetic field generation are suppressed. Particle acceleration, when efficient, modifies the turbulence around the shock on a long time scale, and the accelerated particles have a characteristic energy spectral index of s_{γ}˜eq2.2 in the ultra-relativistic limit. We discuss how this novel understanding of particle acceleration and magnetic field generation in relativistic shocks can be applied to high-energy astrophysical phenomena, with an emphasis on PWNe and GRB afterglows.

  4. Particle Acceleration and Nonthermal Emission in Relativistic Astrophysical Shocks

    NASA Astrophysics Data System (ADS)

    Sironi, Lorenzo

    The common observational feature of Pulsar Wind Nebulae (PWNe), gamma-ray bursts (GRBs), and AGN jets is a broad nonthermal spectrum of synchrotron and inverse Compton radiation. It is usually assumed that the emitting electrons are accelerated to a power-law distribution at relativistic shocks, via the so-called Fermi mechanism. Despite decades of research, the Fermi acceleration process is still not understood from first principles. An assessment of the micro-physics of particle acceleration in relativistic shocks is of paramount importance to unveil the properties of astrophysical nonthermal sources, and it is the subject of this dissertation. In the first part of this thesis, I explore by means of fully-kinetic first-principle particle-in-cell (PIC) simulations the properties of relativistic shocks that propagate in electron-positron and electron-proton plasmas carrying uniform magnetic fields. I find that nonthermal particle acceleration only occurs if the upstream magnetization is weak (sigma<0.001), or if the pre-shock field is nearly aligned with the shock direction of propagation (quasi-parallel shocks). Relativistic shocks in PWNe, GRBs and AGN jets are usually thought to be appreciably magnetized (sigma>0.01) and quasi-perpendicular, yet they need to be efficient particle accelerators, in order to explain the prominent nonthermal signatures of these sources. Motivated by this discrepancy, I then relax the assumption of uniform pre-shock fields, and investigate the acceleration efficiency of perpendicular shocks that propagate in high-sigma flows with alternating magnetic fields. This is the geometry expected at the termination shock of pulsar winds, but it could also be relevant for Poynting-dominated jets in GRBs and AGNs. I show by means of PIC simulations that compression of the flow at the shock will force annihilation of nearby field lines, a process known as shock-driven reconnection. Magnetic reconnection can efficiently transfer the energy of

  5. GPU-Accelerated PIC/MCC Simulation of Laser-Plasma Interaction Using BUMBLEBEE

    NASA Astrophysics Data System (ADS)

    Jin, Xiaolin; Huang, Tao; Chen, Wenlong; Wu, Huidong; Tang, Maowen; Li, Bin

    2015-11-01

    The research of laser-plasma interaction in its wide applications relies on the use of advanced numerical simulation tools to achieve high performance operation while reducing computational time and cost. BUMBLEBEE has been developed to be a fast simulation tool used in the research of laser-plasma interactions. BUMBLEBEE uses a 1D3V electromagnetic PIC/MCC algorithm that is accelerated by using high performance Graphics Processing Unit (GPU) hardware. BUMBLEBEE includes a friendly user-interface module and four physics simulators. The user-interface provides a powerful solid-modeling front end and graphical and computational post processing functionality. The solver of BUMBLEBEE has four modules for now, which are used to simulate the field ionization, electron collisional ionization, binary coulomb collision and laser-plasma interaction processes. The ionization characteristics of laser-neutral interaction and the generation of high-energy electrons have been analyzed by using BUMBLEBEE for validation.

  6. Relativistic electron beam generator

    DOEpatents

    Mooney, L.J.; Hyatt, H.M.

    1975-11-11

    A relativistic electron beam generator for laser media excitation is described. The device employs a diode type relativistic electron beam source having a cathode shape which provides a rectangular output beam with uniform current density.

  7. Viscous photons in relativistic heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Dion, Maxime; Paquet, Jean-François; Schenke, Björn; Young, Clint; Jeon, Sangyong; Gale, Charles

    2011-12-01

    Theoretical studies of the production of real thermal photons in relativistic heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) are performed. The space-time evolution of the colliding system is modelled using music, a 3+1D relativistic hydrodynamic simulation, using both its ideal and viscous versions. The inclusive spectrum and its azimuthal angular anisotropy are studied separately, and the relative contributions of the different photon sources are highlighted. It is shown that the photon v2 coefficient is especially sensitive to the details of the microscopic dynamics like the equation of state, the ratio of shear viscosity over entropy density, η/s, and to the morphology of the initial state.

  8. A 1D (radial) Plasma Jet Propagation Study for the Plasma Liner Experiment (PLX)

    NASA Astrophysics Data System (ADS)

    Thompson, J. R.; Bogatu, I. N.; Galkin, S. A.; Kim, J. S.; Welch, D. R.; Thoma, C.; Golovkin, I.; Macfarlane, J. J.; Case, A.; Messer, S. J.; Witherspoon, F. D.; Cassibry, J. T.; Awe, T. J.; Hsu, S. C.

    2011-10-01

    The Plasma Liner Experiment will explore the formation of imploding spherical ``plasma liners'' that reach peak pressures of 0.1 Mbar upon stagnation. The liners will be formed through the merging of dense, high velocity plasma jets (n ~1017 cm-3, T ~3 eV, v ~50 km/s) in a spherically convergent geometry. The focus of this 1D (radial) study is argon plasma jet evolution during propagation from the rail gun source to the jet merging radius. The study utilizes the Large Scale Plasma (LSP) PIC code with atomic physics included through the use of a non-Local Thermal Equilibrium (NLTE) Equation of State (EOS) table. We will present scenarios for expected 1D (radial) plasma jet evolution, from upon exiting the PLX rail gun to reaching the jet merging radius. The importance of radiation cooling early in the simulation is highlighted. Work supported by US DOE grant DE-FG02-05ER54835.

  9. The PIC [Process Individualization Curriculum] Model: Structure with Humanistic Goals.

    ERIC Educational Resources Information Center

    Gow, Doris T.

    This paper describes a curriculum design model to train research and development personnel under USOE-NIE funding. This design model, called PIC (Process Individualization Curriculum), was chosen for coverting on-campus courses to extra-mural self-instructional courses. The curriculum specialists who work with professors to individualize their…

  10. EXPERIMENTAL INVESTIGATION OF PIC FORMATION IN CFC-12 INCINERATION

    EPA Science Inventory

    The report gives results of experiments to determine the effect of flame zone temperature on gas-phase flame formation and destruction of products of incomplete combustion (PICS) during dichlorodi-fluoromethane (CFC-12) incineration. The effect of water injection into the flame ...

  11. The PIC Youth Primer: Improving JTPA Programs for Youth.

    ERIC Educational Resources Information Center

    Snedeker, Bonnie; And Others

    This guide for Private Industry Council (PIC) officers, members, and staff is written to assist in planning and overseeing effective programs for youth at risk in the local labor market using resources allocated under the Job Training Partnership Act (JTPA). Section I takes a broad view of the problem of building effective employability…

  12. The first Pic du Midi photographs of Mars, 1909

    NASA Astrophysics Data System (ADS)

    Dollfus, A.

    2010-08-01

    This short paper comprises an English translation of the article '1909; Premieres photographies de Mars au Pic du Midi', by Audouin Dollfus, published in l'Astronomie, 2009 November, pp. 27-30, and printed here with the assistance of the Director of the BAA Mars Section, Dr Richard McKim.

  13. Functional design criteria for pumping and instrumentation control (PIC) skids

    SciTech Connect

    BOETTGER, J.S.

    1999-08-25

    Radioactive liquid and semisolid waste from operation of Hanford's nuclear fuel processing plants is stored in 177 underground storage tanks located in the 200 Areas of the Hanford site. 28 of these tanks are of double-shell construction. The remaining 149 tanks are of single-shell construction. Only the newer, double-shell tanks (DST) can meet current requirements for containment of dangerous waste. Therefore, the single-shell tanks (SST) are being ''interim stabilized,'' which is the process of removing liquid from the waste through the use of a jet pump installed in a saltwell which penetrates the waste. Lockheed Martin Hanford Company has decided to purchase additional Pumping and Instrumentation Control (PIC) skids to monitor and control the operation of saltwell jet pumps in SSTs. Similar PIC skids are already in use at several locations. The PIC skids will shut off all power to equipment/instruments if preset limits are exceeded for such conditions as flammable gas, leak detection, pressure and flow, as well as provide air and water necessary for saltwell pumping activities. This document outlines the functional design criteria for pumping and instrumentation control (PIC) skids to support the interim stabilization effort for saltwell pumping.

  14. Mediator coordinates PIC assembly with recruitment of CHD1.

    PubMed

    Lin, Justin J; Lehmann, Lynn W; Bonora, Giancarlo; Sridharan, Rupa; Vashisht, Ajay A; Tran, Nancy; Plath, Kathrin; Wohlschlegel, James A; Carey, Michael

    2011-10-15

    Murine Chd1 (chromodomain helicase DNA-binding protein 1), a chromodomain-containing chromatin remodeling protein, is necessary for embryonic stem (ES) cell pluripotency. Chd1 binds to nucleosomes trimethylated at histone 3 Lys 4 (H3K4me3) near the beginning of active genes but not to bivalent domains also containing H3K27me3. To address the mechanism of this specificity, we reproduced H3K4me3- and CHD1-stimulated gene activation in HeLa extracts. Multidimensional protein identification technology (MuDPIT) and immunoblot analyses of purified preinitiation complexes (PICs) revealed the recruitment of CHD1 to naive chromatin but enhancement on H3K4me3 chromatin. Studies in depleted extracts showed that the Mediator coactivator complex, which controls PIC assembly, is also necessary for CHD1 recruitment. MuDPIT analyses of CHD1-associated proteins support the recruitment data and reveal numerous components of the PIC, including Mediator. In vivo, CHD1 and Mediator are recruited to an inducible gene, and genome-wide binding of the two proteins correlates well with active gene transcription in mouse ES cells. Finally, coimmunoprecipitation of CHD1 and Mediator from cell extracts can be ablated by shRNA knockdown of a specific Mediator subunit. Our data support a model in which the Mediator coordinates PIC assembly along with the recruitment of CHD1. The combined action of the PIC and H3K4me3 provides specificity in targeting CHD1 to active genes.

  15. 46 CFR 13.301 - Original application for “Tankerman-PIC (Barge)” endorsement.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Original application for âTankerman-PIC (Barge)â... OFFICERS AND SEAMEN CERTIFICATION OF TANKERMEN Requirements for âTankerman-PIC (Barge)â Endorsement § 13.301 Original application for “Tankerman-PIC (Barge)” endorsement. Each applicant for a...

  16. Australian Validation of the Hierarchical Personality Inventory for Children (HiPIC)

    ERIC Educational Resources Information Center

    Hopkinson, Laura; Watt, Dianne; Roodenburg, John

    2014-01-01

    The Hierarchical Personality Inventory for Children (HiPIC) is a developmentally appropriate parent-report measure of the Five Factor Model (FFM) that has been validated in several European languages but only recently in English. The English translation of the HiPIC was evaluated in an Australian context. Parent-rated HiPIC scores were obtained…

  17. Relativistically induced transparency acceleration of light ions by an ultrashort laser pulse interacting with a heavy-ion-plasma density gradient

    NASA Astrophysics Data System (ADS)

    Sahai, Aakash A.; Tsung, Frank S.; Tableman, Adam R.; Mori, Warren B.; Katsouleas, Thomas C.

    2013-10-01

    The relativistically induced transparency acceleration (RITA) scheme of proton and ion acceleration using laser-plasma interactions is introduced, modeled, and compared to the existing schemes. Protons are accelerated with femtosecond relativistic pulses to produce quasimonoenergetic bunches with controllable peak energy. The RITA scheme works by a relativistic laser inducing transparency [Akhiezer and Polovin, Zh. Eksp. Teor. Fiz 30, 915 (1956); Kaw and Dawson, Phys. FluidsPFLDAS0031-917110.1063/1.1692942 13, 472 (1970); Max and Perkins, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.27.1342 27, 1342 (1971)] to densities higher than the cold-electron critical density, while the background heavy ions are stationary. The rising laser pulse creates a traveling acceleration structure at the relativistic critical density by ponderomotively [Lindl and Kaw, Phys. FluidsPFLDAS0031-917110.1063/1.1693437 14, 371 (1971); Silva , Phys. Rev. E1063-651X10.1103/PhysRevE.59.2273 59, 2273 (1999)] driving a local electron density inflation, creating an electron snowplow and a co-propagating electrostatic potential. The snowplow advances with a velocity determined by the rate of the rise of the laser's intensity envelope and the heavy-ion-plasma density gradient scale length. The rising laser is incrementally rendered transparent to higher densities such that the relativistic-electron plasma frequency is resonant with the laser frequency. In the snowplow frame, trace density protons reflect off the electrostatic potential and get snowplowed, while the heavier background ions are relatively unperturbed. Quasimonoenergetic bunches of velocity equal to twice the snowplow velocity can be obtained and tuned by controlling the snowplow velocity using laser-plasma parameters. An analytical model for the proton energy as a function of laser intensity, rise time, and plasma density gradient is developed and compared to 1D and 2D PIC OSIRIS [Fonseca , Lect. Note Comput. Sci.9783

  18. 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.

  19. Relativistic soliton collisions of axion type dark matter

    NASA Astrophysics Data System (ADS)

    Castañeda Valle, David; Mielke, Eckehard W.

    2016-07-01

    Axion-like scalar fields and the Lane-Emden (LE) truncation of their periodic potential are analyzed as a toy model of dark matter halos. Then, collisions of the well-known kinks in (1 + 1) spacetime dimensions can be mapped to those of localized lumps of the LE equation. Here, we generalize this mapping to (2 + 1)D or even (3 + 1)D and discuss a challenging intrinsic inelastic effect during relativistic soliton collisions.

  20. Relativistic Linear Restoring Force

    ERIC Educational Resources Information Center

    Clark, D.; Franklin, J.; Mann, N.

    2012-01-01

    We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke's law to be the force appearing on the right-hand side of the relativistic expressions: d"p"/d"t" or d"p"/d["tau"]. Either formulation recovers Hooke's law in the non-relativistic limit. In addition to these two forces, we…

  1. Relativistic Guiding Center Equations

    SciTech Connect

    White, R. B.; Gobbin, M.

    2014-10-01

    In toroidal fusion devices it is relatively easy that electrons achieve relativistic velocities, so to simulate runaway electrons and other high energy phenomena a nonrelativistic guiding center formalism is not sufficient. Relativistic guiding center equations including flute mode time dependent field perturbations are derived. The same variables as used in a previous nonrelativistic guiding center code are adopted, so that a straightforward modifications of those equations can produce a relativistic version.

  2. The Serine Protease Autotransporter Pic Modulates Citrobacter rodentium Pathogenesis and Its Innate Recognition by the Host.

    PubMed

    Bhullar, Kirandeep; Zarepour, Maryam; Yu, Hongbing; Yang, Hong; Croxen, Matthew; Stahl, Martin; Finlay, B Brett; Turvey, Stuart E; Vallance, Bruce A

    2015-07-01

    Bacterial pathogens produce a number of autotransporters that possess diverse functions. These include the family of serine protease autotransporters of Enterobacteriaceae (SPATEs) produced by enteric pathogens such as Shigella flexneri and enteroaggregative Escherichia coli. Of these SPATEs, one termed "protein involved in colonization," or Pic, has been shown to possess mucinase activity in vitro, but to date, its role in in vivo enteric pathogenesis is unknown. Testing a pic null (ΔpicC) mutant in Citrobacter rodentium, a natural mouse pathogen, found that the C. rodentium ΔpicC strain was impaired in its ability to degrade mucin in vitro compared to the wild type. Upon infection of mice, the ΔpicC mutant exhibited a hypervirulent phenotype with dramatically heavier pathogen burdens found in intestinal crypts. ΔpicC mutant-infected mice suffered greater barrier disruption and more severe colitis and weight loss, necessitating their euthanization between 10 and 14 days postinfection. Notably, the virulence of the ΔpicC mutant was normalized when the picC gene was restored; however, a PicC point mutant causing loss of mucinase activity did not replicate the ΔpicC phenotype. Exploring other aspects of PicC function, the ΔpicC mutant was found to aggregate to higher levels in vivo than wild-type C. rodentium. Moreover, unlike the wild type, the C. rodentium ΔpicC mutant had a red, dry, and rough (RDAR) morphology in vitro and showed increased activation of the innate receptor Toll-like receptor 2 (TLR2). Interestingly, the C. rodentium ΔpicC mutant caused a degree of pathology similar to that of wild-type C. rodentium when infecting TLR2-deficient mice, showing that despite its mucinase activity, PicC's major role in vivo may be to limit C. rodentium's stimulation of the host's innate immune system.

  3. Hardware acceleration of PIC codes: tapping into the power of state of the art processing units

    NASA Astrophysics Data System (ADS)

    Fonseca, R. A.; Abreu, P.; Martins, S. F.; Silva, L. O.

    2008-11-01

    There are many astrophysical and laboratory scenarios where kinetic effects play an important role. Further understanding of these scenarios requires detailed numerical modeling using fully relativistic three-dimensional kinetic code such as OSIRIS [1]. However, these codes are computationally heavy. Explicitly using available hardware resources such as SIMD units (Altivec/SSE3) [2], cell processors or graphics processing units (GPUs) may allow us to significantly boost performance of these codes. For the most cases, the processing units are limited to single precision arithmetic, and require specific C/C++ code to be used. We present a comparison between double precision and single precision results, focusing both on performance and on the effects on the simulation in terms of algorithm properties. Details on a framework allowing the integration of hardware optimized routines with existing high performance codes in languages other than C is given. Finally, initial results of high performance modules of the PIC algorithm using SIMD units and GPU's will also be presented. [1] R. A. Fonseca et al., LNCS 2331, 342, (2002) [2] K. J. Bowers et al., Phys Plasmas vol. 15 (5) pp. 055703 (2008)

  4. Phototriggered sulfoxide isomerization in [Ru(pic)2(dmso)2].

    PubMed

    Rachford, Aaron A; Petersen, Jeffrey L; Rack, Jeffrey J

    2007-08-14

    We report the characterization and photochemistry of a simple ruthenium coordination complex containing only picolinate (pic) and dmso, which exhibits a large isomerization quantum yield (Phi(SS-->OO) = 0.50) in various solvents. The picolinate ligands of [Ru(pic)(2)(dmso)(2)] are in a cis arrangement so that the carboxylate oxygen of one pic ligand (O1) is trans to the pyridine of the second picolinate (N2). One dmso ligand (S1) is trans to a pyridine nitrogen (N1), while the second dmso (S2) is trans to a carboxylate oxygen (O3). The cyclic voltammetry, (1)H NMR, IR, and UV-vis spectroscopy data suggest that while both dmso ligands isomerize photochemically, only one dmso ligand isomerizes electrochemically. Isomerization quantum yields for each dmso ligand differ by an order of magnitude (Phi(SS-->SO) = 0.46 and Phi(SO-->OO) = 0.036). In agreement with previous results, the isomerization quantum yield for each dmso is dependent on the ligand that is trans to the dmso.

  5. Blazar flares powered by plasmoids in relativistic reconnection

    NASA Astrophysics Data System (ADS)

    Petropoulou, Maria; Giannios, Dimitrios; Sironi, Lorenzo

    2016-11-01

    Powerful flares from blazars with short (˜min) variability time-scales are challenging for current models of blazar emission. Here, we present a physically motivated ab initio model for blazar flares based on the results of recent particle-in-cell (PIC) simulations of relativistic magnetic reconnection. PIC simulations demonstrate that quasi-spherical plasmoids filled with high-energy particles and magnetic fields are a self-consistent by-product of the reconnection process. By coupling our PIC-based results (i.e. plasmoid growth, acceleration profile, particle and magnetic content) with a kinetic equation for the evolution of the electron distribution function we demonstrate that relativistic reconnection in blazar jets can produce powerful flares whose temporal and spectral properties are consistent with the observations. In particular, our model predicts correlated synchrotron and synchrotron self-Compton flares of duration of several hours-days powered by the largest and slowest moving plasmoids that form in the reconnection layer. Smaller and faster plasmoids produce flares of sub-hour duration with higher peak luminosities than those powered by the largest plasmoids. Yet, the observed fluence in both types of flares is similar. Multiple flares with a range of flux-doubling time-scales (minutes to several hours) observed over a longer period of flaring activity (days or longer) may be used as a probe of the reconnection layer's orientation and the jet's magnetization. Our model shows that blazar flares are naturally expected as a result of magnetic reconnection in a magnetically dominated jet.

  6. Upstream Design and 1D-CAE

    NASA Astrophysics Data System (ADS)

    Sawada, Hiroyuki

    Recently, engineering design environment of Japan is changing variously. Manufacturing companies are being challenged to design and bring out products that meet the diverse demands of customers and are competitive against those produced by rising countries(1). In order to keep and strengthen the competitiveness of Japanese companies, it is necessary to create new added values as well as conventional ones. It is well known that design at the early stages has a great influence on the final design solution. Therefore, design support tools for the upstream design is necessary for creating new added values. We have established a research society for 1D-CAE (1 Dimensional Computer Aided Engineering)(2), which is a general term for idea, methodology and tools applicable for the upstream design support, and discuss the concept and definition of 1D-CAE. This paper reports our discussion about 1D-CAE.

  7. Boltzmann electron PIC simulation of the E-sail effect

    NASA Astrophysics Data System (ADS)

    Janhunen, P.

    2015-12-01

    The solar wind electric sail (E-sail) is a planned in-space propulsion device that uses the natural solar wind momentum flux for spacecraft propulsion with the help of long, charged, centrifugally stretched tethers. The problem of accurately predicting the E-sail thrust is still somewhat open, however, due to a possible electron population trapped by the tether. Here we develop a new type of particle-in-cell (PIC) simulation for predicting E-sail thrust. In the new simulation, electrons are modelled as a fluid, hence resembling hybrid simulation, but in contrast to normal hybrid simulation, the Poisson equation is used as in normal PIC to calculate the self-consistent electrostatic field. For electron-repulsive parts of the potential, the Boltzmann relation is used. For electron-attractive parts of the potential we employ a power law which contains a parameter that can be used to control the number of trapped electrons. We perform a set of runs varying the parameter and select the one with the smallest number of trapped electrons which still behaves in a physically meaningful way in the sense of producing not more than one solar wind ion deflection shock upstream of the tether. By this prescription we obtain thrust per tether length values that are in line with earlier estimates, although somewhat smaller. We conclude that the Boltzmann PIC simulation is a new tool for simulating the E-sail thrust. This tool enables us to calculate solutions rapidly and allows to easily study different scenarios for trapped electrons.

  8. PicSafe Medi: a clinical photography app review.

    PubMed

    Lo, Michelle Chin I; Brinkworth, Simon; Knights, Christina; Mackie, Ian

    2015-01-01

    Medical photographs are used in many clinical settings; however, there are significant risks associated with using the camera feature on mobile devices, namely, breaches of security. PicSafe Medi is an app that allows healthcare professionals to take clinical photographs using smart devices whilst addressing the concerns of patient confidentiality. We review the app to assess its functionality in a UK clinical setting, taking into account UK guidelines such as those offered by the General Medical Council, UK legislation, the Institute of Medical Illustrators and the Department of Health. PMID:26828558

  9. Ion and Electron Dynamics in Nonlinear PIC Simulations

    SciTech Connect

    Jolliet, S.; Angelino, P.; Tran, T. M.; McMillan, B. F.; Sauter, O.; Villard, L.; Bottino, A.; Peeters, A. G.; Poli, E.; Hatzky, R.

    2006-11-30

    ITG and ETG turbulence is investigated with the nonlinear global PIC code ORB5. The large variety of numerical schemes and simulations domains used has sometimes lead to important discrepancies in the transport predictions. In order to discuss these disagreements, emphasis must be put on ways to check the numerical accuracy, such as energy conservation and numerical noise measurement. This paper therefore presents benchmarks, new algorithms and a noise diagnostic. After having demonstrated the numerical quality of our simulations, 2 topics are visited: the unclear role of the parallel nonlinearity and the transport level in ETG turbulence, for which predictions differing by one order of magnitude had been made elsewhere.

  10. PicSafe Medi: a clinical photography app review.

    PubMed

    Lo, Michelle Chin I; Brinkworth, Simon; Knights, Christina; Mackie, Ian

    2015-01-01

    Medical photographs are used in many clinical settings; however, there are significant risks associated with using the camera feature on mobile devices, namely, breaches of security. PicSafe Medi is an app that allows healthcare professionals to take clinical photographs using smart devices whilst addressing the concerns of patient confidentiality. We review the app to assess its functionality in a UK clinical setting, taking into account UK guidelines such as those offered by the General Medical Council, UK legislation, the Institute of Medical Illustrators and the Department of Health.

  11. Relativistic Gravity Research

    NASA Astrophysics Data System (ADS)

    Ehlers, Jürgen; Schäfer, Gerhard

    17 readable articles give a thorough and self-contained overview of recent developments in relativistic gravity research. The subjects covered are: gravitational lensing, the general relativistic n-body problem, observable effects in the solar system, gravitational waves and their interferometric detection, very-long-baseline interferometry, international atomic time, lunar laserranging measurements, measurement of the gravitomagnetic field of the Earth, fermion and boson stars and black holes with hair, rapidly rotating neutron stars, matter wave interferometry, and the laboratory test of Newton's law of gravity. Any scientist interested in experimentally or observatio- nally oriented relativistic gravity will read the book with profit. In addition, it is perfectly suited as a complementary text for courses on general relativity and relativistic astrophysics.

  12. Relativistic spherical plasma waves

    NASA Astrophysics Data System (ADS)

    Bulanov, S. S.; Maksimchuk, A.; Schroeder, C. B.; Zhidkov, A. G.; Esarey, E.; Leemans, W. P.

    2012-02-01

    Tightly focused laser pulses that diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we study theoretically and numerically relativistic spherical wake waves and their properties, including wave breaking.

  13. Weakly relativistic plasma expansion

    SciTech Connect

    Fermous, Rachid Djebli, Mourad

    2015-04-15

    Plasma expansion is an important physical process that takes place in laser interactions with solid targets. Within a self-similar model for the hydrodynamical multi-fluid equations, we investigated the expansion of both dense and under-dense plasmas. The weakly relativistic electrons are produced by ultra-intense laser pulses, while ions are supposed to be in a non-relativistic regime. Numerical investigations have shown that relativistic effects are important for under-dense plasma and are characterized by a finite ion front velocity. Dense plasma expansion is found to be governed mainly by quantum contributions in the fluid equations that originate from the degenerate pressure in addition to the nonlinear contributions from exchange and correlation potentials. The quantum degeneracy parameter profile provides clues to set the limit between under-dense and dense relativistic plasma expansions at a given density and temperature.

  14. Relativistic Quantum Scars

    SciTech Connect

    Huang, Liang; Lai Yingcheng; Ferry, David K.; Goodnick, Stephen M.; Akis, Richard

    2009-07-31

    The concentrations of wave functions about classical periodic orbits, or quantum scars, are a fundamental phenomenon in physics. An open question is whether scarring can occur in relativistic quantum systems. To address this question, we investigate confinements made of graphene whose classical dynamics are chaotic and find unequivocal evidence of relativistic quantum scars. The scarred states can lead to strong conductance fluctuations in the corresponding open quantum dots via the mechanism of resonant transmission.

  15. Exact Relativistic `Antigravity' Propulsion

    NASA Astrophysics Data System (ADS)

    Felber, Franklin S.

    2006-01-01

    The Schwarzschild solution is used to find the exact relativistic motion of a payload in the gravitational field of a mass moving with constant velocity. At radial approach or recession speeds faster than 3-1/2 times the speed of light, even a small mass gravitationally repels a payload. At relativistic speeds, a suitable mass can quickly propel a heavy payload from rest nearly to the speed of light with negligible stresses on the payload.

  16. A new species of Pseudopyrochroa Pic, 1906 (Coleoptera: Pyrochroidae: Pyrochroinae) from the Mae Chaem District, Thailand.

    PubMed

    Young, Daniel K

    2014-04-02

    A new species of the fire-colored beetle genus Pseudopyrochroa Pic, 1906, is described from the Mae Chaem District, Chiang Mai Province, Thailand. The new species, Pseudopyrochroa inthanonensis sp. nov., is superficially similar to Pseudopyrochroa basalis (Pic), Pseudopyrochroa cardoni (Fairmaire) and Pseudopyrochroa fainanensis (Pic) by virtue of body color, antennal form and prothoracic shape. It is the second species of the genus known from Thailand, the other being Pseudopyrochroa diversicornis (Blair).

  17. PIC Simulation of the Electron Whistler Heat Flux Instability in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Choi, E.; Min, K.; Roberts, D. A.; Hwang, K. J.; Sibeck, D. G.; Dokgo, K.

    2015-12-01

    Electrons in the solar wind are often observed as two distinguishable components; a thermal dense core and a suprathermal halo. The relative drift and anisotropy of these two electron components determine the electron heat flux, which can excite various electromagnetic instabilities. Among these, the whistler has been found to be one of the most commonly-observed and important instabilities. The electron parameters derived from the measured solar wind are comparable to the threshold values predicted by the linear Vlasov theory of the whistler heat flux instability. The enhanced magnetic field fluctuations driven by the heat flux instability, in turn, prevent the drift speed difference between the two populations from increasing. This indicates that the electron heat flux is constrained and regulated by heat flux instabilities through the wave-particle scattering. Such electron heat flux regulation has widely been observed and in best agreement with the whistler heat flux instability. Here we present the growth of the electron heat flux instability in the solar wind condition using 1D PIC simulation with a periodic boundary condition. The two Maxwellian electron components are found to predominantly excite the whistler waves. We examine the growth rates of the whistle instability with respect to various plasma parameters such as the difference in drift speeds between the two components and temperature of the halo, to show the electron heat flux regulation by the whistler.

  18. DESIGN PACKAGE 1D SYSTEM SAFETY ANALYSIS

    SciTech Connect

    L.R. Eisler

    1995-02-02

    The purpose of this analysis is to systematically identify and evaluate hazards related to the Yucca Mountain Project Exploratory Studies Facility (ESF) Design Package 1D, Surface Facilities, (for a list of design items included in the package 1D system safety analysis see section 3). This process is an integral part of the systems engineering process; whereby safety is considered during planning, design, testing, and construction. A largely qualitative approach was used since a radiological System Safety analysis is not required. The risk assessment in this analysis characterizes the accident scenarios associated with the Design Package 1D structures/systems/components in terms of relative risk and includes recommendations for mitigating all identified risks. The priority for recommending and implementing mitigation control features is: (1) Incorporate measures to reduce risks and hazards into the structure/system/component (S/S/C) design, (2) add safety devices and capabilities to the designs that reduce risk, (3) provide devices that detect and warn personnel of hazardous conditions, and (4) develop procedures and conduct training to increase worker awareness of potential hazards, on methods to reduce exposure to hazards, and on the actions required to avoid accidents or correct hazardous conditions. The scope of this analysis is limited to the Design Package 1D structures/systems/components (S/S/Cs) during normal operations excluding hazards occurring during maintenance and ''off normal'' operations.

  19. Relativistic effects in chemistry

    SciTech Connect

    Yatsimirskii, K.B.

    1995-11-01

    Relativistic effects become apparent when the velocity of the electron is arbitrarily close to the speed of light (137 au) without actually attaining it (in heavy atoms of elements at the end of Mendeleev`s Periodic Table). At the orbital level, the relativistic effect is apparent in the radial contraction of penetrating s and p shells, expansion of nonpenetrating d and f shells, and the spin-orbit splitting of p-,d-, and f-shells. The appearance of a relativistic effect is indicated in the variation in the electronic configurations of the atoms in the Periodic Table, the appearance of new types of closed electron shells (6s{sub 1/2}{sup 2}, 6p{sub 1/2}{sup 2}, 7s{sub 1/2}{sup 2}, 5d{sub 3/2}{sup 4}), the stabilization of unstable oxidation states of heavy elements, the characteristic variation in the ionization enthalpies of heavy atoms, their electron affinity, hydration energies, redox potentials, and optical electronegativities. In the spectra of coordination compounds, a relativistic effect is observed when comparing the position of the charge transfer bands in analogous compounds, the parameters characterizing the ligand field strength (10Dq), the interatomic distances and angles in compounds of heavy elements. A relativistic effect is also apparent in the ability of heavy metals to form clusters and superclusters. Relativistic corrections also affect other properties of heavy metal compounds (force constants, dipole moments, biological activity, etc.).

  20. Relativistic viscoelastic fluid mechanics

    SciTech Connect

    Fukuma, Masafumi; Sakatani, Yuho

    2011-08-15

    A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.

  1. Relativistic viscoelastic fluid mechanics.

    PubMed

    Fukuma, Masafumi; Sakatani, Yuho

    2011-08-01

    A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.

  2. Benchmarking the codes VORPAL, OSIRIS, and QuickPIC with Laser Wakefield Acceleration Simulations

    SciTech Connect

    Paul, Kevin; Huang, C.; Bruhwiler, D.L.; Mori, W.B.; Tsung, F.S.; Cormier-Michel, E.; Geddes, C.G.R.; Cowan, B.; Cary, J.R.; Esarey, E.; Fonseca, R.A.; Martins, S.F.; Silva, L.O.

    2008-09-08

    Three-dimensional laser wakefield acceleration (LWFA) simulations have recently been performed to benchmark the commonly used particle-in-cell (PIC) codes VORPAL, OSIRIS, and QuickPIC. The simulations were run in parallel on over 100 processors, using parameters relevant to LWFA with ultra-short Ti-Sapphire laser pulses propagating in hydrogen gas. Both first-order and second-order particle shapes were employed. We present the results of this benchmarking exercise, and show that accelerating gradients from full PIC agree for all values of a0 and that full and reduced PIC agree well for values of a0 approaching 4.

  3. Benchmarking the codes VORPAL, OSIRIS, and QuickPIC with Laser Wakefield Acceleration Simulations

    SciTech Connect

    Paul, K.; Bruhwiler, D. L.; Cowan, B.; Cary, J. R.; Huang, C.; Mori, W. B.; Tsung, F. S.; Cormier-Michel, E.; Geddes, C. G. R.; Esarey, E.; Fonseca, R. A.; Martins, S. F.; Silva, L. O.

    2009-01-22

    Three-dimensional laser wakefield acceleration (LWFA) simulations have recently been performed to benchmark the commonly used particle-in-cell (PIC) codes VORPAL, OSIRIS, and QuickPIC. The simulations were run in parallel on over 100 processors, using parameters relevant to LWFA with ultra-short Ti-Sapphire laser pulses propagating in hydrogen gas. Both first-order and second-order particle shapes were employed. We present the results of this benchmarking exercise, and show that accelerating gradients from full PIC agree for all values of a{sub 0} and that full and reduced PIC agree well for values of a{sub 0} approaching 4.

  4. Temperature and Light Control of Three phase Induction Motor Speed Drive by PIC

    NASA Astrophysics Data System (ADS)

    Barsoum, Nader

    2010-06-01

    PIC is a family of Harvard architecture microcontrollers made by Microchip Technology, derived from the PIC1640 originally developed by General Instrument's Microelectronics Division. The name PIC initially referred to "Peripheral Interface Controller". PICs are popular with the developers and the hobbyists due to their low cost, wide availability, large user base, extensive collection of application notes, free development tools, and serial programming (and re-programming with flash memory) capability. In modern days, PIC microcontrollers are used in the industrial world to control many types of equipment, ranging from consumer to specialized devices. They have replaced older types of controllers, including microprocessors. Also, there is a growing need for off-line support of a computer's main processor. The demand is going to grow with more equipment uses more intelligence. In the engineering field for instance, PIC has brought a very positive impact in designing an automation control system and controlling industrial machineries. Accordingly, this paper shows the change in the motor speed by the use of PIC in accordance to the light and level of temperature. The project focuses on programming the PIC by embedded software that detects the temperature and light signals and send it to 3 phase induction motor of 240 volt. A theoretical analysis and the practical approach in achieving this work goal have proved that PIC plays an important role in the field of electronics control.

  5. Modelling RF sources using 2-D PIC codes

    SciTech Connect

    Eppley, K.R.

    1993-03-01

    In recent years, many types of RF sources have been successfully modelled using 2-D PIC codes. Both cross field devices (magnetrons, cross field amplifiers, etc.) and pencil beam devices (klystrons, gyrotrons, TWT`S, lasertrons, etc.) have been simulated. All these devices involve the interaction of an electron beam with an RF circuit. For many applications, the RF structure may be approximated by an equivalent circuit, which appears in the simulation as a boundary condition on the electric field (``port approximation``). The drive term for the circuit is calculated from the energy transfer between beam and field in the drift space. For some applications it may be necessary to model the actual geometry of the structure, although this is more expensive. One problem not entirely solved is how to accurately model in 2-D the coupling to an external waveguide. Frequently this is approximated by a radial transmission line, but this sometimes yields incorrect results. We also discuss issues in modelling the cathode and injecting the beam into the PIC simulation.

  6. Modelling RF sources using 2-D PIC codes

    SciTech Connect

    Eppley, K.R.

    1993-03-01

    In recent years, many types of RF sources have been successfully modelled using 2-D PIC codes. Both cross field devices (magnetrons, cross field amplifiers, etc.) and pencil beam devices (klystrons, gyrotrons, TWT'S, lasertrons, etc.) have been simulated. All these devices involve the interaction of an electron beam with an RF circuit. For many applications, the RF structure may be approximated by an equivalent circuit, which appears in the simulation as a boundary condition on the electric field ( port approximation''). The drive term for the circuit is calculated from the energy transfer between beam and field in the drift space. For some applications it may be necessary to model the actual geometry of the structure, although this is more expensive. One problem not entirely solved is how to accurately model in 2-D the coupling to an external waveguide. Frequently this is approximated by a radial transmission line, but this sometimes yields incorrect results. We also discuss issues in modelling the cathode and injecting the beam into the PIC simulation.

  7. On specular reflectivity measurements in high and low-contrast relativistic laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Kemp, G. E.; Link, A.; Ping, Y.; McLean, H. S.; Patel, P. K.; Freeman, R. R.; Schumacher, D. W.; Tiedje, H. F.; Tsui, Y. Y.; Ramis, R.; Fedosejevs, R.

    2015-01-01

    Using both experiment and 2D3V particle-in-cell (PIC) simulations, we describe the use of specular reflectivity measurements to study relativistic (Iλ2 > 1018 W/cm2ṡμm2) laser-plasma interactions for both high and low-contrast 527 nm laser pulses on initially solid density aluminum targets. In the context of hot-electron generation, studies typically rely on diagnostics which, more-often-than-not, represent indirect processes driven by fast electrons transiting through solid density materials. Specular reflectivity measurements, however, can provide a direct measure of the interaction that is highly sensitive to how the EM fields and plasma profiles, critical input parameters for modeling of hot-electron generation, evolve near the interaction region. While the fields of interest occur near the relativistic critical electron density, experimental reflectivity measurements are obtained centimeters away from the interaction region, well after diffraction has fully manifested itself. Using a combination of PIC simulations with experimentally inspired conditions and an analytic, non-paraxial, pulse propagation algorithm, we calculate reflected pulse properties, both near and far from the interaction region, and compare with specular reflectivity measurements. The experiment results and PIC simulations demonstrate that specular reflectivity measurements are an extremely sensitive qualitative, and partially quantitative, indicator of initial laser/target conditions, ionization effects, and other details of intense laser-matter interactions. The techniques described can provide strong constraints on many systems of importance in ultra-intense laser interactions with matter.

  8. A relativistic toy model for Unruh black holes

    NASA Astrophysics Data System (ADS)

    Carbonaro, P.

    2014-08-01

    We consider the wave propagation in terms of acoustic geometry in a quantum relativistic system. This reduces, in the hydrodynamic limit, to the equations which govern the motion of a relativistic Fermi-degenerate gas in one space dimension. The derivation of an acoustic metric for one-dimensional (1D) systems is in general plagued with the impossibility of defining a conformal factor. Here we show that, although the system is intrinsically one-dimensional, the Unruh procedure continues to work because of the particular structure symmetry of the model. By analyzing the dispersion relation, attention is also paid to the quantum effects on the wave propagation.

  9. Centrosome Positioning in 1D Cell Migration

    NASA Astrophysics Data System (ADS)

    Adlerz, Katrina; Aranda-Espinoza, Helim

    During cell migration, the positioning of the centrosome and nucleus define a cell's polarity. For a cell migrating on a two-dimensional substrate the centrosome is positioned in front of the nucleus. Under one-dimensional confinement, however, the centrosome is positioned behind the nucleus in 60% of cells. It is known that the centrosome is positioned by CDC42 and dynein for cells moving on a 2D substrate in a wound-healing assay. It is currently unknown, however, if this is also true for cells moving under 1D confinement, where the centrosome position is often reversed. Therefore, centrosome positioning was studied in cells migrating under 1D confinement, which mimics cells migrating through 3D matrices. 3 to 5 μm fibronectin lines were stamped onto a glass substrate and cells with fluorescently labeled nuclei and centrosomes migrated on the lines. Our results show that when a cell changes directions the centrosome position is maintained. That is, when the centrosome is between the nucleus and the cell's trailing edge and the cell changes direction, the centrosome will be translocated across the nucleus to the back of the cell again. A dynein inhibitor did have an influence on centrosome positioning in 1D migration and change of directions.

  10. Assessment of PIC and MMPI Scales in Adolescent Psychosis: A Caution.

    ERIC Educational Resources Information Center

    Davies, Allison; And Others

    1987-01-01

    Investigated sensitivity of Personality Inventory for Children (PIC) and Minnesota Multiphasic Personality Inventory (MMPI) in assessing psychotic states in adolescents. Results from comparison of 29 psychotic and 58 nonpsychotic adolescent psychiatric inpatients suggest the need for a profile-analytic approach to PIC and MMPI interpretation in…

  11. Evaluation of Age, Sex, and Race Bias in the Personality Inventory for Children (PIC).

    ERIC Educational Resources Information Center

    Kline, Rex B.; Lachar, David

    1992-01-01

    Whether the external validity of the Personality Inventory for Children (PIC) was moderated by age, sex, or race was studied using 1,333 children and adolescents referred for mental health services. Race and sex generally did not moderate the relation of PIC scales to symptom checklists. Some relationships were age modified. (SLD)

  12. Preparation of PLLA/bpV(pic) microspheres and their effect on nerve cells.

    PubMed

    Lin, Qiang; Chen, Hai-yun; Li, Hao-shen; Cai, Yang-ting

    2014-02-01

    In this study, we prepared PLLA/bpV(pic) microspheres, a bpV(pic) controlled release system and examined their ability to protect nerve cells and promote axonal growth. PLLA microspheres were prepared by employing the o/w single emulsification-evaporation technique. Neural stem cells and dorsal root ganglia were divided into 3 groups in terms of the treatment they received: a routine medium group (cultured in DMEM), a PLLA microsphere group (DMEM containing PLLA microspheres alone) and a PLLA/bpV(pic) group [DMEM containing PLLA/bpV(pic) microspheres]. The effects of PLLA/bpV(pic) microspheres were evaluated by the live-dead test and measurement of axonal length. Our results showed that PLLA/bpV(pic) granulation rate was (88.2±5.6)%; particle size was (16.8±3.1)%, drug loading was (4.05±0.3)%; encapsulation efficiency was (48.5±1.8)%. The release time lasted for 30 days. In PLLA/bpV(pic) microsphere group, the cell survival rate was (95.2 ±4.77)%, and the length of dorsal root ganglion (DRG) was 718±95 μm, which were all significantly greater than those in ordinary routine medium group and PLLA microsphere group. This preliminary test results showed the PLLA/bpV(pic) microspheres were successfully prepared and they could promote the survival and growth of neural cells in DRG.

  13. Planning, Management and Evaluation: Realizing PIC Potential. Private Industry Council Guide. Working Draft.

    ERIC Educational Resources Information Center

    National Alliance of Business, Inc., Washington, DC.

    This Planning, Management, and Evaluation (PME) guide was developed by the National Alliance of Business as part of its program of management assistance for Private Industry Councils (PICs). The guide is a tool which PICs can use to improve their capability to plan, manage, and evaluate the programs which they administer, and to establish locally…

  14. Micro-PIC. A Simple Form of the Profile of Interaction in the Classroom.

    ERIC Educational Resources Information Center

    Forbes, Joan

    The Profile of Interaction in the Classroom (PIC) is a feedback method of interaction analysis, based on the Flanders System, created for supervisors of pre-service and in-service teacher education. The Micro-PIC is an abbreviated simplified form for analysis of shorter periods of interaction, particularly in microteaching. The Micro-PIC…

  15. PIC. Profile of Interaction in the Classroom. A Quick Feedback of Interaction Analysis.

    ERIC Educational Resources Information Center

    Brunner, Ellen

    The Profile of Interaction in the Classroom (PIC) is a short-cut method of interaction analysis that can provide the quick feedback essential to effective supervision of instruction. And because the PIC contains a record of all the behaviors that occurred in the classroom, as well as the sequence, the data may be used to build a traditional…

  16. Screening Preschoolers with Special Problems: Use of the Personality Inventory for Children (PIC).

    ERIC Educational Resources Information Center

    Keenan, P. A.; Lachar, David

    The Personality Inventory for Children (PIC) is an objectively scored, multidimensional measure of child and adolescent behavior, affect, and cognitive ability and can be completed by parents. The overall goal of this project was to evaluate the psychometric characteristics of the PIC as a screening device for use with preschool populations. The…

  17. The serine protease Pic as a virulence factor of atypical enteropathogenic Escherichia coli.

    PubMed

    Abreu, Afonso G; Abe, Cecilia M; Nunes, Kamila O; Moraes, Claudia T P; Chavez-Dueñas, Lucia; Navarro-Garcia, Fernando; Barbosa, Angela S; Piazza, Roxane M F; Elias, Waldir P

    2016-01-01

    Autotransporter proteins (AT) are associated with bacterial virulence attributes. Originally identified in enteroaggregative Escherichia coli (EAEC), Shigella flexneri 2a and uropathogenic E. coli, the serine protease Pic is one of these AT. We have previously detected one atypical enteropathogenic E. coli strain (BA589) carrying the pic gene. In the present study, we characterized the biological activities of Pic produced by BA589 both in vitro and in vivo. Contrarily to other Pic-producers bacteria, pic in BA589 is located on a high molecular weight plasmid. PicBA589 was able to agglutinate rabbit erythrocytes, cleave mucin and degrade complement system molecules. BA589 was able to colonize mice intestines, and an intense mucus production was observed. The BA589Δpic mutant lost the capacity to colonize as well as the above-mentioned in vitro activities. Thus, Pic represents an additional virulence factor in aEPEC strain BA589, associated with adherence, colonization and evasion from the innate immune system.

  18. SAMPEX Relativistic Microbursts Observation

    NASA Astrophysics Data System (ADS)

    Liang, X.; Comess, M.; Smith, D. M.; Selesnick, R. S.; Sample, J. G.; Millan, R. M.

    2012-12-01

    Relativistic (>1 MeV) electron microburst precipitation is thought to account for significant relativistic electron loss. We present the statistical and spectral analysis of relativistic microbursts observed by the Proton/Electron Telescope (PET) on board the Solar Anomalous Magnetospheric Particle Explorer(SAMPEX) satellite from 1992 to 2004. Spectrally we find that microbursts are well fit by an exponential energy distribution in the 0.5-4 MeV range with a spectral e-folding energy of E0 < 375 keV. We also discuss the comparison of morning microbursts with events at midnight, which were first identified as microbursts by O'Brien et al. (2004). Finally, we compare the loss-rates due to microbursts and non-microburst precipitation during storm times and averaged over all times.

  19. Relativistic Weierstrass random walks.

    PubMed

    Saa, Alberto; Venegeroles, Roberto

    2010-08-01

    The Weierstrass random walk is a paradigmatic Markov chain giving rise to a Lévy-type superdiffusive behavior. It is well known that special relativity prevents the arbitrarily high velocities necessary to establish a superdiffusive behavior in any process occurring in Minkowski spacetime, implying, in particular, that any relativistic Markov chain describing spacetime phenomena must be essentially Gaussian. Here, we introduce a simple relativistic extension of the Weierstrass random walk and show that there must exist a transition time t{c} delimiting two qualitative distinct dynamical regimes: the (nonrelativistic) superdiffusive Lévy flights, for trelativistic) Gaussian diffusion, for t>t{c} . Implications of this crossover between different diffusion regimes are discussed for some explicit examples. The study of such an explicit and simple Markov chain can shed some light on several results obtained in much more involved contexts. PMID:20866862

  20. Relativistic Bursian diode equilibria

    SciTech Connect

    Ender, A. Y.; Kuznetsov, V. I.; Schamel, H.

    2011-03-15

    A comprehensive study of steady-states of a planar vacuum diode driven by a cold relativistic electron beam is presented. The emitter electric field as a characteristic function for their existence is evaluated in dependence of the diode length, the applied potential V, and the relativistic beam factor at injection {gamma}{sub 0}. It is used to classify the different branches of possible solutions, which encompass electron flows that are (i) transmitted through the diode completely, (ii) partially reflected from a virtual cathode (VC) either within the diode region or at the collector side, and (iii) reflected totally. As a byproduct, the V and {gamma}{sub 0} dependences of both bifurcation points of the minimum potential and of the transmitted current are obtained and the ultrarelativistic limit, {gamma}{sub 0}>>1, is performed. In this highly relativistic regime, the density of electrons appears to be constant across the diode region except for a small area around the VC.

  1. Relativistic Weierstrass random walks.

    PubMed

    Saa, Alberto; Venegeroles, Roberto

    2010-08-01

    The Weierstrass random walk is a paradigmatic Markov chain giving rise to a Lévy-type superdiffusive behavior. It is well known that special relativity prevents the arbitrarily high velocities necessary to establish a superdiffusive behavior in any process occurring in Minkowski spacetime, implying, in particular, that any relativistic Markov chain describing spacetime phenomena must be essentially Gaussian. Here, we introduce a simple relativistic extension of the Weierstrass random walk and show that there must exist a transition time t{c} delimiting two qualitative distinct dynamical regimes: the (nonrelativistic) superdiffusive Lévy flights, for trelativistic) Gaussian diffusion, for t>t{c} . Implications of this crossover between different diffusion regimes are discussed for some explicit examples. The study of such an explicit and simple Markov chain can shed some light on several results obtained in much more involved contexts.

  2. Non-linear PIC simulation in a penning trap

    SciTech Connect

    Delzanno, G. L.; Lapenta, G. M.; Finn, J. M.

    2001-01-01

    We study the non-linear dynamics of a Penning trap plasma, including the effect of the finite length and end curvature of the plasma column. A new cylindrical PIC code, called KANDINSKY, has been implemented by using a new interpolation scheme. The principal idea is to calculate the volume of each cell from a particle volume, in the same manner as it is done for the cell charge. With this new method, the density is conserved along streamlines and artificial sources of compressibility are avoided. The code has been validated with a reference Eulerian fluid code. We compare the dynamics of three different models: a model with compression effects, the standard Euler model and a geophysical fluid dynamics model. The results of our investigation prove that Penning traps can really be used to simulate geophysical fluids.

  3. Modeling of Ionization Physics with the PIC Code OSIRIS

    SciTech Connect

    Deng, S.; Tsung, F.; Lee, S.; Lu, W.; Mori, W.B.; Katsouleas, T.; Muggli, P.; Blue, B.E.; Clayton, C.E.; O'Connell, C.; Dodd, E.; Decker, F.J.; Huang, C.; Hogan, M.J.; Hemker, R.; Iverson, R.H.; Joshi, C.; Ren, C.; Raimondi, P.; Wang, S.; Walz, D.; /Southern California U. /UCLA /SLAC

    2005-09-27

    When considering intense particle or laser beams propagating in dense plasma or gas, ionization plays an important role. Impact ionization and tunnel ionization may create new plasma electrons, altering the physics of wakefield accelerators, causing blue shifts in laser spectra, creating and modifying instabilities, etc. Here we describe the addition of an impact ionization package into the 3-D, object-oriented, fully parallel PIC code OSIRIS. We apply the simulation tool to simulate the parameters of the upcoming E164 Plasma Wakefield Accelerator experiment at the Stanford Linear Accelerator Center (SLAC). We find that impact ionization is dominated by the plasma electrons moving in the wake rather than the 30 GeV drive beam electrons. Impact ionization leads to a significant number of trapped electrons accelerated from rest in the wake.

  4. Perspective: relativistic effects.

    PubMed

    Autschbach, Jochen

    2012-04-21

    This perspective article discusses some broadly-known and some less broadly-known consequences of Einstein's special relativity in quantum chemistry, and provides a brief outline of the theoretical methods currently in use, along with a discussion of recent developments and selected applications. The treatment of the electron correlation problem in relativistic quantum chemistry methods, and expanding the reach of the available relativistic methods to calculate all kinds of energy derivative properties, in particular spectroscopic and magnetic properties, requires on-going efforts. PMID:22519307

  5. Relativistic nuclear dynamics

    SciTech Connect

    Coester, F.

    1985-01-01

    A review is presented of three distinct approaches to the construction of relativistic dynamical models: (1) Relativistic canonical quantum mechanics. (The Hilbert space of states is independent of the interactions, which are introduced by modifying the energy operator.) (2) Hilbert spaces of manifestly covariant wave functions. (The interactions modify the metric of the Hilbert space.) (3) Covariant Green functions. In each of the three approaches the focus is on the formulation of the two-body dynamics, and problems in the construction of the corresponding many-body dynamics are discussed briefly. 21 refs.

  6. Perspective: relativistic effects.

    PubMed

    Autschbach, Jochen

    2012-04-21

    This perspective article discusses some broadly-known and some less broadly-known consequences of Einstein's special relativity in quantum chemistry, and provides a brief outline of the theoretical methods currently in use, along with a discussion of recent developments and selected applications. The treatment of the electron correlation problem in relativistic quantum chemistry methods, and expanding the reach of the available relativistic methods to calculate all kinds of energy derivative properties, in particular spectroscopic and magnetic properties, requires on-going efforts.

  7. PICS: Simulations of Strong Gravitational Lensing in Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Li, Nan; Gladders, Michael D.; Rangel, Esteban M.; Florian, Michael K.; Bleem, Lindsey E.; Heitmann, Katrin; Habib, Salman; Fasel, Patricia

    2016-09-01

    Gravitational lensing has become one of the most powerful tools available for investigating the “dark side” of the universe. Cosmological strong gravitational lensing, in particular, probes the properties of the dense cores of dark matter halos over decades in mass and offers the opportunity to study the distant universe at flux levels and spatial resolutions otherwise unavailable. Studies of strongly lensed variable sources offer even further scientific opportunities. One of the challenges in realizing the potential of strong lensing is to understand the statistical context of both the individual systems that receive extensive follow-up study, as well as that of the larger samples of strong lenses that are now emerging from survey efforts. Motivated by these challenges, we have developed an image simulation pipeline, Pipeline for Images of Cosmological Strong lensing (PICS), to generate realistic strong gravitational lensing signals from group- and cluster-scale lenses. PICS uses a low-noise and unbiased density estimator based on (resampled) Delaunay Tessellations to calculate the density field; lensed images are produced by ray-tracing images of actual galaxies from deep Hubble Space Telescope observations. Other galaxies, similarly sampled, are added to fill in the light cone. The pipeline further adds cluster member galaxies and foreground stars into the lensed images. The entire image ensemble is then observed using a realistic point-spread function that includes appropriate detector artifacts for bright stars. Noise is further added, including such non-Gaussian elements as noise window-paning from mosaiced observations, residual bad pixels, and cosmic rays. The aim is to produce simulated images that appear identical—to the eye (expert or otherwise)—to real observations in various imaging surveys.

  8. High temperature decreases the PIC / POC ratio and increases phosphorus requirements in Coccolithus pelagicus (Haptophyta)

    NASA Astrophysics Data System (ADS)

    Gerecht, A. C.; Šupraha, L.; Edvardsen, B.; Probert, I.; Henderiks, J.

    2014-01-01

    Rising ocean temperatures will likely increase stratification of the water column and reduce nutrient input into the photic zone. This will increase the likelihood of nutrient limitation in marine microalgae, leading to changes in the abundance and composition of phytoplankton communities, which in turn will affect global biogeochemical cycles. Calcifying algae, such as coccolithophores, influence the carbon cycle by fixing CO2 into particulate organic carbon (POC) through photosynthesis and into particulate inorganic carbon (PIC) through calcification. As calcification produces a net release of CO2, the ratio of PIC / POC determines whether coccolithophores act as a source (PIC / POC > 1) or a sink (PIC / POC < 1) of atmospheric CO2. We studied the effect of phosphorus (P-) limitation and temperature stress on the physiology and PIC / POC ratios of two subspecies of Coccolithus pelagicus. This large and heavily calcified species (PIC / POC generally > 1.5) is a major contributor to calcite export from the photic zone into deep-sea reservoirs. Phosphorus limitation did not influence exponential growth rates in either subspecies, but P-limited cells had significantly lower cellular P-content. A 5 °C temperature increase did not affect exponential growth rates either, but nearly doubled cellular P-content under both high and low phosphate availability. The PIC / POC ratios did not differ between P-limited and nutrient-replete cultures, but at elevated temperature (from 10 to 15 °C) PIC / POC ratios decreased by 40-60%. Our results suggest that elevated temperature may intensify P-limitation due to a higher P-requirement to maintain growth and POC production rates, possibly reducing abundances in a warmer ocean. Under such a scenario C. pelagicus may decrease its calcification rate relative to photosynthesis, resulting in PIC / POC ratios < 1 and favouring CO2-sequestration over release. Phosphorus limitation by itself is unlikely to cause changes in the PIC / POC

  9. Generation of uniform relativistic electron layer and linear and nonlinear coherent Thomson scattering

    NASA Astrophysics Data System (ADS)

    Wu, Hui-Chun; Meyer-Ter-Vehn, J.; Fernandez, J. C.; Hegelich, B. M.

    2010-11-01

    A novel, multi-layer target [H.-C. Wu et al., PRL 104, 234801 (2010)] is proposed to generate uniform relativistic electron layers for coherent Thomson backscattering (CTS). A few-cycle laser pulse produces an electron layer from an ultrathin foil and then a second foil reflects the laser pulse, but lets the electrons pass through unperturbed. 2D-PIC simulations show that after interacting with the drive and reflected laser pulses, the electrons form a very uniform flyer that propagates in the direction of laser propagation. Such a flyer backscatters light with a full Doppler shift factor of 4γ^2. Nonlinear CTS theory for relativistic laser intensity shows that compared with linear CTS, a relativistically intense laser induces transverse motion of the electron layer and decreases the linear Doppler shift by a factor 1+a0^2 . Consequently, in order to obtain the same x-ray photon energy as linear CTS, the nonlinear case needs higher electron energy. Theory also shows that CTS efficiency reaches saturation when laser amplitudea0>2. PIC simulations show that a powerful x-ray pulse (1 keV, 10 attoseconds, and GW power) can be generated and that diffraction-limited focusing may boost the intensity to of order 10^24W/cm^2.

  10. 3-D RPIC simulations of relativistic jets: Particle acceleration, magnetic field generation, and emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.

    2006-01-01

    Nonthermal radiation observed from astrophysical systems containing (relativistic) jets and shocks, e.g., supernova remnants, active galactic nuclei (AGNs), gamma-ray bursts (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. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the .shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations which show particle acceleration in jets.

  11. A 1-D dusty plasma photonic crystal

    SciTech Connect

    Mitu, M. L.; Ticoş, C. M.; Toader, D.; Banu, N.; Scurtu, A.

    2013-09-21

    It is demonstrated numerically that a 1-D plasma crystal made of micron size cylindrical dust particles can, in principle, work as a photonic crystal for terahertz waves. The dust rods are parallel to each other and arranged in a linear string forming a periodic structure of dielectric-plasma regions. The dispersion equation is found by solving the waves equation with the boundary conditions at the dust-plasma interface and taking into account the dielectric permittivity of the dust material and plasma. The wavelength of the electromagnetic waves is in the range of a few hundred microns, close to the interparticle separation distance. The band gaps of the 1-D plasma crystal are numerically found for different types of dust materials, separation distances between the dust rods and rod diameters. The distance between levitated dust rods forming a string in rf plasma is shown experimentally to vary over a relatively wide range, from 650 μm to about 1350 μm, depending on the rf power fed into the discharge.

  12. Relativistic impulse dynamics.

    PubMed

    Swanson, Stanley M

    2011-08-01

    Classical electrodynamics has some annoying rough edges. The self-energy of charges is infinite without a cutoff. The calculation of relativistic trajectories is difficult because of retardation and an average radiation reaction term. By reconceptuallizing electrodynamics in terms of exchanges of impulses rather than describing it by forces and potentials, we eliminate these problems. A fully relativistic theory using photonlike null impulses is developed. Numerical calculations for a two-body, one-impulse-in-transit model are discussed. A simple relationship between center-of-mass scattering angle and angular momentum was found. It reproduces the Rutherford cross section at low velocities and agrees with the leading term of relativistic distinguishable-particle quantum cross sections (Møller, Mott) when the distance of closest approach is larger than the Compton wavelength of the particle. Magnetism emerges as a consequence of viewing retarded and advanced interactions from the vantage point of an instantaneous radius vector. Radiation reaction becomes the local conservation of energy-momentum between the radiating particle and the emitted impulse. A net action is defined that could be used in developing quantum dynamics without potentials. A reinterpretation of Newton's laws extends them to relativistic motion.

  13. The Relativistic Rocket

    ERIC Educational Resources Information Center

    Antippa, Adel F.

    2009-01-01

    We solve the problem of the relativistic rocket by making use of the relation between Lorentzian and Galilean velocities, as well as the laws of superposition of successive collinear Lorentz boosts in the limit of infinitesimal boosts. The solution is conceptually simple, and technically straightforward, and provides an example of a powerful…

  14. Relativistic effects on plasma expansion

    SciTech Connect

    Benkhelifa, El-Amine; Djebli, Mourad

    2014-07-15

    The expansion of electron-ion plasma is studied through a fully relativistic multi-fluids plasma model which includes thermal pressure, ambipolar electrostatic potential, and internal energy conversion. Numerical investigation, based on quasi-neutral assumption, is performed for three different regimes: nonrelativistic, weakly relativistic, and relativistic. Ions' front in weakly relativistic regime exhibits spiky structure associated with a break-down of quasi-neutrality at the expanding front. In the relativistic regime, ion velocity is found to reach a saturation limit which occurs at earlier stages of the expansion. This limit is enhanced by higher electron velocity.

  15. 46 CFR 13.305 - Proof of service for “Tankerman-PIC (Barge)” endorsement.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Proof of service for âTankerman-PIC (Barge)â endorsement... AND SEAMEN CERTIFICATION OF TANKERMEN Requirements for âTankerman-PIC (Barge)â Endorsement § 13.305 Proof of service for “Tankerman-PIC (Barge)” endorsement. Service must be proved by a letter on...

  16. APERIODIC MAGNETIC TURBULENCE PRODUCED BY RELATIVISTIC ION BEAMS

    SciTech Connect

    Niemiec, Jacek; Pohl, Martin; Bret, Antoine; Stroman, Thomas

    2010-02-01

    Magnetic-field generation by a relativistic ion beam propagating through an electron-ion plasma along a homogeneous magnetic field is investigated with 2.5D high-resolution particle-in-cell (PIC) simulations. The studies test predictions of a strong amplification of short-wavelength modes of magnetic turbulence upstream of nonrelativistic and relativistic parallel shocks associated with supernova remnants (SNRs), jets of active galactic nuclei, and gamma-ray bursts. We find a good agreement in the properties of the turbulence observed in our simulations compared with the dispersion relation calculated for linear waves with arbitrary orientation of k-vector. Depending on the parameters, the back-reaction on the ion beam leads to filamentation of the ambient plasma and the beam, which in turn influences the properties of the magnetic turbulence. For mildly and ultrarelativistic beams, the instability saturates at field amplitudes a few times larger than the homogeneous magnetic field strength. This result matches our recent studies of nonrelativistically drifting, hot cosmic-ray particles upstream of SNR shocks which indicated only a moderate magnetic-field amplification by nonresonant instabilities. We also demonstrate that the aperiodic turbulence generated by the beam can provide efficient particle scattering with a rate compatible with Bohm diffusion. Representing the ion beam as a constant external current, i.e., excluding a back-reaction of the magnetic turbulence on the beam, we observe nonresonant parallel modes with wavelength and growth rate as predicted by analytic calculations. In this unrealistic setup, the magnetic field is amplified to amplitudes far exceeding the homogeneous field, as observed in recent magnetohydrodynamic and PIC simulations.

  17. 1D fast coded aperture camera.

    PubMed

    Haw, Magnus; Bellan, Paul

    2015-04-01

    A fast (100 MHz) 1D coded aperture visible light camera has been developed as a prototype for imaging plasma experiments in the EUV/X-ray bands. The system uses printed patterns on transparency sheets as the masked aperture and an 80 channel photodiode array (9 V reverse bias) as the detector. In the low signal limit, the system has demonstrated 40-fold increase in throughput and a signal-to-noise gain of ≈7 over that of a pinhole camera of equivalent parameters. In its present iteration, the camera can only image visible light; however, the only modifications needed to make the system EUV/X-ray sensitive are to acquire appropriate EUV/X-ray photodiodes and to machine a metal masked aperture. PMID:25933861

  18. 1D fast coded aperture camera.

    PubMed

    Haw, Magnus; Bellan, Paul

    2015-04-01

    A fast (100 MHz) 1D coded aperture visible light camera has been developed as a prototype for imaging plasma experiments in the EUV/X-ray bands. The system uses printed patterns on transparency sheets as the masked aperture and an 80 channel photodiode array (9 V reverse bias) as the detector. In the low signal limit, the system has demonstrated 40-fold increase in throughput and a signal-to-noise gain of ≈7 over that of a pinhole camera of equivalent parameters. In its present iteration, the camera can only image visible light; however, the only modifications needed to make the system EUV/X-ray sensitive are to acquire appropriate EUV/X-ray photodiodes and to machine a metal masked aperture.

  19. 1D-VAR Retrieval Using Superchannels

    NASA Technical Reports Server (NTRS)

    Liu, Xu; Zhou, Daniel; Larar, Allen; Smith, William L.; Schluessel, Peter; Mango, Stephen; SaintGermain, Karen

    2008-01-01

    Since modern ultra-spectral remote sensors have thousands of channels, it is difficult to include all of them in a 1D-var retrieval system. We will describe a physical inversion algorithm, which includes all available channels for the atmospheric temperature, moisture, cloud, and surface parameter retrievals. Both the forward model and the inversion algorithm compress the channel radiances into super channels. These super channels are obtained by projecting the radiance spectra onto a set of pre-calculated eigenvectors. The forward model provides both super channel properties and jacobian in EOF space directly. For ultra-spectral sensors such as Infrared Atmospheric Sounding Interferometer (IASI) and the NPOESS Airborne Sounder Testbed Interferometer (NAST), a compression ratio of more than 80 can be achieved, leading to a significant reduction in computations involved in an inversion process. Results will be shown applying the algorithm to real IASI and NAST data.

  20. Nuclear import of the pre-integration complex (PIC): the Achilles heel of HIV?

    PubMed

    Piller, S C; Caly, L; Jans, D A

    2003-07-01

    Current treatments against the Aquired immune deficiency syndrome (AIDS) are reasonably effective in reducing the amount of human immunodeficiency virus (HIV) present in infected patients, but their side-effects, and the emergence of drug-resistant HIV strains have intensified the renewed search for novel anti-HIV therapies. An essential step in HIV infection is the integration of the viral genome into the host cell chromosomes within the nucleus. Unlike other retroviruses, HIV can transport its genetic material, in the form of the large nucleoprotein pre-integration complex (PIC), into the nucleus through the intact nuclear envelope (NE). This enables HIV to infect non-dividing cells such as macrophages and microglial cells. Detailed knowledge of the signal-dependent pathways by which cellular proteins and RNAs cross the NE has accumulated in the past decade, but although several different components of the PIC have been implicated in its nuclear import, the mechanism of nuclear entry remains unclear. Since specifically inhibiting PIC nuclear import would undoubtedly block HIV infection in non-dividing cells, this critical step of HIV replication is of great interest as a drug target. This review examines the complex and controversial literature regarding three PIC components--the HIV proteins matrix, integrase and Vpr--proposed to facilitate PIC nuclear import, and existing models of HIV PIC nuclear import. It also suggests approaches to move towards a better understanding of PIC nuclear import, through examining the role of individual PIC components in the context of the intact PIC by direct visualisation, in order to develop new anti-HIV therapeutics.

  1. Fountain effect of laser-driven relativistic electrons inside a solid dielectric

    SciTech Connect

    Sarkisov, G. S.; Jobe, D.; Spielman, R.; Leblanc, P.; Ivanov, V. V.; Sentoku, Y.; Yates, K.; Wiewior, P.; Bychenkov, V. Yu.

    2011-09-26

    Ultrafast interferometry with sub-ps resolution has been applied for the direct measurement of an electron density induced by a laser-driven relativistic electron beam inside a solid dielectric. The topology of the interference phase shift shows the signature of the ''fountain effect,'' a narrow electron beam that fans out from the propagation axis and heads back to the target surface. Two-dimensional particle-in-cell (PIC) computer simulations demonstrate radial spreading of fast electrons by self-consistent electrostatic fields. The very low ionization, {approx}0.1%, observed after the heating pulse suggests a fast recombination at the sub-ps time scale.

  2. Taxonomy of Fissocantharis Pic (Coleoptera, Cantharidae) from Guangxi, China, with descriptions of six new species.

    PubMed

    Yang, Yuxia; Li, Limei; Guan, Kaile; Yang, Xingke

    2015-01-01

    A total of 17 species of Fissocantharis Pic is recorded from Guangxi, China. Six species are described new to science, Fissocantharissinensomima sp. n., Fissocantharissexcostata sp. n., Fissocantharisbasilaris sp. n., Fissocanthariseschara sp. n., Fissocantharislatipalpa sp. n. and Fissocantharisbiprojicientis sp. n., and two previously known species are redescribed, Fissocantharisgracilipes (Pic, 1927) and Fissocantharissinensis (Wittmer, 1988). These species are presented with habitus of males, abdominal sternites VIII of females and genitalia of both sexes. Fissocantharisflavofacialis (Pic, 1926) is synonymized with Fissocantharisangusta (Fairmaire, 1900); both were originally described in the genus Podabrus Westwood. Additionally, a key and a checklist of all the species of Fissocantharis from Guangxi are provided.

  3. Detailed numerical modeling of electron injection in the Laser Wakefield Accelerator: Particle Tracking Diagnostics in PIC codes

    NASA Astrophysics Data System (ADS)

    Fonseca, R. A.; Gargaté, L.; Martins, S. F.; Peano, F.; Vieira, J.; Silva, L. O.; Mori, W. B.

    2007-11-01

    The field of laser plasma acceleration has witnessed significant development over recent years, with experimental demonstrations of the production of quasi mono-energetic electron bunches, with charges of ˜ 50 pC and energies of up to 1 GeV [1]. Fully relativistic PIC codes, such as OSIRIS [2] are the best tools for modeling these problems, but sophisticated visualization and data analysis routines [3] are required to extract physical meaning from the large volumes of data produced. We report on the new particle tracking diagnostics being added into the OSIRIS framework and its application to this problem, specifically targeting self-injection. Details on the tracking algorithm implementation and post processing routines are given. Simulation results from laser wakefield accelerator scenarios will be presented, with detailed analysis of the self injection of the electron bunches. [1] W.P. Leemans et al, Nature Phys. 2 696 (2006) [2] R. A. Fonseca et al., LNCS 2331, 342, (2002) [3] R. A. Fonseca, Proceedings of ISSS-7, (2005)

  4. PIC Simulations of the Omega-EP Magnetic Reconnection Experiment

    NASA Astrophysics Data System (ADS)

    Liu, Wenda; Blackman, Eric; Yan, Rui; Ren, Chuang

    2014-10-01

    In an Omega EP experiment on magnetic reconnection, two laser beams with peak intensity of 7 × 1018 W/cm2 are focused on a Cu-target. Here we report 2D PIC simulation results with parameters derived from the experiment including a realistic ion-electron mass ratio. We find that 1) toroidal and mega-gauss-scale magnetic fields are generated and a bubble of high-energy-density plasma is produced from single beam-target interactions and 2) the magnetic topology changes as two such bubbles expand and interact with each other indicating the occurrence of magnetic reconnection. The reconnection can occur even when the bubble expansion velocity is subsonic. Flux pileup is observed when the expansion velocity is supersonic. Energetic Cu-ions with energy up to 12 MeV are also observed in the outflow. This work was supported by NNSA under Corporate Agreement No. DE-FC52-08NA28302 and Grant No. DE-NA0002205; by DOE under Grant No. DE-FC02-04ER54789; and by NSF under Grant No. PHY-1314734.

  5. Emulsification through surfactant hydration: the PIC process revisited.

    PubMed

    Roger, Kevin; Cabane, Bernard; Olsson, Ulf

    2011-01-18

    We have performed sudden composition changes on a (surfactant + oil + water) system by adding water to a (surfactant + oil) solution. This composition change quenches the system into a metastable oil-in-water emulsion with a population in the 100 nm range. The conditions for a successful quench are as follows: the initial water content should be below a boundary called the "clearing boundary" (CB), the final water content should be sufficiently beyond CB, and the quench should be fast. We have used high purity components to avoid the complex phase separation patterns that occur with low purity ingredients: the surfactant is octaethylenehexadecyl ether (C(16)E(8)) and the oil is hexadecane (C(16)). Under these conditions, we show that the pathway for this type of quench proceeds through the swelling of the reverse micellar phase by the added water and the formation of a sponge phase. Then, further water addition causes the nucleation of oil droplets in this sponge phase, with a size that matches the spontaneous curvature of the sponge phase. Part of the surfactant remains adsorbed on these droplets, and the rest is expelled as micelles that coexist with the droplets. It is concluded that a PIC emulsification will always lead to a bimodal size distribution with surfactant "wasted" in small micelles. This is in contrast with the more efficient PIT emulsification.

  6. Relativistic Pseudospin Symmetry

    SciTech Connect

    Ginocchio, Joseph N.

    2011-05-06

    We show that the pseudospin symmetry that Akito Arima discovered many years ago (with collaborators) is a symmetry of the the Dirac Hamiltonian for which the sum of the scalar and vector potentials are a constant. In this paper we discuss some of the implications of this relativistic symmetry and the experimental data that support these predictions. In his original paper Akito also discussed pseudo-U(3) symmetry. We show that pseudo-U(3) symmetry is a symmetry of the Dirac Hamiltonian for which the sum of harmonic oscillator vector and scalar potentials are equal to a constant, and we give the generators of pseudo-U(3) symmetry. Going beyond the mean field we summarize new results on non relativistic shell model Hamiltonians that have pseudospin symmetry and pseudo-orbital angular momentum symmetry as a dynamical symmetries.

  7. Relativistic multiwave Cerenkov generators

    SciTech Connect

    Bugaev, S.P.; Cherepenin, V.A.; Kanavets, V.I.; Klimov, A.I.; Kopenkin, A.D.; Koshelev, V.I.; Popov, V.A.; Slepkov, A.I. )

    1990-06-01

    A review of research on relativistic multiwave Cherenkov generators (MWCG) is provided. Presented is the linear theory of these devices, allowing a detailed description of multiwave interaction of a relativistic electron beam with an electromagnetic field in an electro-dynamic superdimensional MWCG system. The results of theoretical research on the starting parameters of generation, power flows, and the structure of the radiated field in a MWCG of a 3-cm-wave band are reported. The experiments on obtaining and investigating high-power pulses of microwave radiation in a MWCG of 3-cm- and 8-mm-wavelength bands are described. In particular, the results of research on a MWCG with the power of 15 GW in a 3-cm-wavelength band and the power of 3 GW in a 8-mm-wavelength band are presented. The results of research of spatial and temporal coherence of such generator radiation are reported.

  8. Relativistic shell model calculations

    NASA Astrophysics Data System (ADS)

    Furnstahl, R. J.

    1986-06-01

    Shell model calculations are discussed in the context of a relativistic model of nuclear structure based on renormalizable quantum field theories of mesons and baryons (quantum hadrodynamics). The relativistic Hartree approximation to the full field theory, with parameters determined from bulk properties of nuclear matter, predicts a shell structure in finite nuclei. Particle-hole excitations in finite nuclei are described in an RPA calculation based on this QHD ground state. The particle-hole interaction is prescribed by the Hartree ground state, with no additional parameters. Meson retardation is neglected in deriving the RPA equations, but it is found to have negligible effects on low-lying states. The full Dirac matrix structure is maintained throughout the calculation; no nonrelativistic reductions are made. Despite sensitive cancellations in the ground state calculation, reasonable excitation spectra are obtained for light nuclei. The effects of including charged mesons, problems with heavy nuclei, and prospects for improved and extended calculations are discussed.

  9. Relativistic electrons in space.

    NASA Technical Reports Server (NTRS)

    Simnett, G. M.

    1972-01-01

    This paper reviews the current state of knowledge concerning relativistic electrons, above 0.3 MeV, in interplanetary space, as measured by detectors on board satellites operating beyond the influence of the magnetosphere. The electrons have a galactic component, which at the lower energies is subject both to solar modulation and to spasmodic 'quiet time' increases and a direct solar component correlated with flare activity. The recent measurements have established the form of the differential energy spectrum of solar flare electrons. Electrons have been detected from flares behind the visible solar disk. Relativistic electrons do not appear to leave the sun at the time of the flash phase of the flare, although there are several signatures of electron acceleration at this time. The delay is interpreted as taking place during the transport of the electrons through the lower corona.

  10. Dielectric cavity relativistic magnetron

    NASA Astrophysics Data System (ADS)

    Hashemi, S. M. A.

    2010-02-01

    An alteration in the structure of the A6 relativistic magnetron is proposed, which introduces an extra degree of freedom to its design and enhances many of its quality factors. This modification involves the partial filling of the cavities of the device with a low-loss dielectric material. The operation of a dielectric-filled A6 is simulated; the results indicate single-mode operation at the desired π mode and a substantially cleaner rf spectrum.

  11. Genetic and molecular analyses of picA, a plant-inducible locus on the Agrobacterium tumefaciens chromosome.

    PubMed Central

    Rong, L J; Karcher, S J; Gelvin, S B

    1991-01-01

    picA is an Agrobacterium tumefaciens chromosomal locus, identified by Mu d11681 mutagenesis, that is inducible by certain acidic polysaccharides found in carrot root extract. Cloning and genetic analysis of a picA::lacZ fusion defined a region of the picA promoter that is responsible for the induction of this locus. Furthermore, we identified a possible negative regulator of picA expression upstream of the picA locus. This sequence, denoted pgl, has extensive homology to polygalacturonase genes from several organisms and inhibited the induction of the picA promoter when present in multiple copies in A. tumefaciens. DNA sequence analysis indicated at least two long open reading frames (ORFs) in the picA region. S1 nuclease mapping was used to identify the transcription initiation site of picA. Mutation of ORF1, but not ORF2, of the picA locus was responsible for an increased aggregation of A. tumefaciens, forming "ropes" in the presence of pea root cap cells. In addition, a potato tuber disk virulence assay indicated that a preinduced picA mutant was more virulent than was the wild-type control, a further indication that the picA locus regulates the surface properties of the bacterium in the presence of plant cells or plant cell extracts. Images PMID:1860822

  12. Relativistic tidal disruption events

    NASA Astrophysics Data System (ADS)

    Levan, A.

    2012-12-01

    In March 2011 Swift detected an extremely luminous and long-lived outburst from the nucleus of an otherwise quiescent, low luminosity (LMC-like) galaxy. Named Swift J1644+57, its combination of high-energy luminosity (1048 ergs s-1 at peak), rapid X-ray variability (factors of >100 on timescales of 100 seconds) and luminous, rising radio emission suggested that we were witnessing the birth of a moderately relativistic jet (Γ ˜ 2 - 5), created when a star is tidally disrupted by the supermassive black hole in the centre of the galaxy. A second event, Swift J2058+0516, detected two months later, with broadly similar properties lends further weight to this interpretation. Taken together this suggests that a fraction of tidal disruption events do indeed create relativistic outflows, demonstrates their detectability, and also implies that low mass galaxies can host massive black holes. Here, I briefly outline the observational properties of these relativistic tidal flares observed last year, and their evolution over the first year since their discovery.

  13. Point form relativistic quantum mechanics and relativistic SU(6)

    NASA Technical Reports Server (NTRS)

    Klink, W. H.

    1993-01-01

    The point form is used as a framework for formulating a relativistic quantum mechanics, with the mass operator carrying the interactions of underlying constituents. A symplectic Lie algebra of mass operators is introduced from which a relativistic harmonic oscillator mass operator is formed. Mass splittings within the degenerate harmonic oscillator levels arise from relativistically invariant spin-spin, spin-orbit, and tensor mass operators. Internal flavor (and color) symmetries are introduced which make it possible to formulate a relativistic SU(6) model of baryons (and mesons). Careful attention is paid to the permutation symmetry properties of the hadronic wave functions, which are written as polynomials in Bargmann spaces.

  14. A new species of the genus Falsoibidion Pic (Coleoptera, Cerambycidae) from Korea

    PubMed Central

    Lee, Seunghyun; Lee, Seunghwan

    2016-01-01

    Abstract A new species of the genus Falsoibidion Pic, 1922 (Coleoptera, Cerambycidae, Cerambycinae, Callidiopini) from Korea is described. Habitus and genitalia of male and female of the new species are illustrated. PMID:27563272

  15. A new species of the genus Falsoibidion Pic (Coleoptera, Cerambycidae) from Korea.

    PubMed

    Lee, Seunghyun; Lee, Seunghwan

    2016-01-01

    A new species of the genus Falsoibidion Pic, 1922 (Coleoptera, Cerambycidae, Cerambycinae, Callidiopini) from Korea is described. Habitus and genitalia of male and female of the new species are illustrated.

  16. Duskside relativistic electron precipitation

    NASA Astrophysics Data System (ADS)

    Lorentzen, Kirsten Ruth

    1999-10-01

    On August 20, 1996, a balloon-borne X-ray pinhole camera and a high resolution germanium X-ray spectrometer observed an intense X-ray event near Kiruna, Sweden, at 1835 MLT, on an L-shell of 5.8. This X-ray event consisted of seven bursts spaced 100-200 seconds apart, with smaller 10-20 second variations observed within individual bursts. The energy spectra of these bursts show the presence of X-rays with energies greater than 1 MeV, which are best accounted for by atmospheric bremsstrahlung from mono-energetic 1.7 MeV precipitating electrons. The X-ray imager observed no significant motion or small-scale spatial structure in the event, implying that the bursts were temporal in nature. Ultra- violet images from the Polar satellite and energetic particle data from the Los Alamos geosynchronous satellites show a small magnetospheric substorm onset about 24 minutes before the start of the relativistic precipitation event. Since the balloon was south of the auroral oval and there was no associated increase in relativistic electron flux at geosynchronous altitude, the event must be the result of some mechanism selectively precipitating ambient relativistic electrons from the radiation belts. The balloon X-ray observations are analyzed in a magnetospheric context, in order to determine which of several mechanisms for selective precipitation of relativistic electrons can account for the event. Resonance with electromagnetic ion cyclotron mode waves on the equator is the most likely candidate. The drift of substorm-injected warm protons is calculated using input from the geosynchronous satellites. Wave growth in the model is driven by temperature anisotropies in the warm proton population. A numerical solution of the wave dispersion relation shows that electromagnetic ion cyclotron waves can be excited in high-density duskside regions such as the plasmasphere or detached plasma regions. These waves can selectively precipitate relativistic electrons of energy 1.7 MeV in

  17. Simulation of Relativistic Shocks and Associated Radiation from Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; 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

  18. The genus Dromanthomorphus Pic, 1921 (Coleoptera, Cleroidea: Malachiidae) in South-East Asia.

    PubMed

    Tshernyshev, Sergei E

    2016-07-22

    South-East Asian species of the genus Dromanthomorphus Pic, 1921 and several species provisionally attributed to Hadrocnemus Kraatz, 1895 are studied, and their taxonomic position is specified. Three new species are described from the Philippines: D. subflabellatus Tshernyshev, sp. n., D. restrictus Tshernyshev, sp. n. and D. subtilis Tshernyshev, sp. n. Seven species are transferred from Hadrocnemus to Dromanthomorphus, D. apoensis (Wittmer, 1999) comb. n., D. blaisei (Pic, 1926) comb. n., D. chiangensis (Wittmer, 1999) comb. n., D. depressicornis (Pic, 1919) comb. n., D. gravieri (Pic, 1923) comb. n., D. javanus (Wittmer, 1989) comb. n. and D. tonkineus (Pic, 1919) comb. n. Three species are transferred from Dromanthomorphus to Oculapalochrus Tshernyshev, 2015, O. ranuensis Wittmer 1990 comb. n., O. saigonensis (Pic, 1951) comb. n. and O. suttoni Wittmer, 1995 comb. n., and two species from Dromanthomorphus to Mimapalochrus Tshernyshev, 2015, M. cingalensis (Champion, 1921) comb. n. and M. dolokensis Wittmer, 1999 comb. n. Illustrations of male external appearance, metathoracic appendage, urites and genitalia, and distribution maps are provided. A determination key to all species of Dromanthomorphus from South-East Asia is also proposed.

  19. Relativistic interactions and realistic applications

    SciTech Connect

    Hoch, T.; Madland, D.; Manakos, P.; Mannel, T.; Nikolaus, B.A.; Strottman, D. |

    1992-12-31

    A four-fermion-coupling Lagrangian (relativistic Skyrme-type) interaction has been proposed for relativistic nuclear structure calculations. This interaction, which has the merit of simplicity, is from the outset tailored as an effective interaction for relativistic Hartree-Fock calculations. Various extensions of such a model are discussed and compared with Walecka`s meson-nucleon mean field approach. We also present results of the calculation of nuclear ground state properties with an extended (density dependent) version of the four fermion interaction in a relativistic Hartree-Fock approximation.

  20. Simulation of Pulse Shortening in a Relativistic Klystron Oscillator

    NASA Astrophysics Data System (ADS)

    Verboncoeur, J. P.; Cartwright, K. L.

    1996-11-01

    The relativistic klystron is a strong candidate for a high power microwave source for a number of applications; one of the impediments to higher power and longer pulses is shortening of the RF pulse compared to the current pulse. In this work, we simulate a high power, high perveance relativistic klystron oscillator(K. J. Hendricks, P. D. Coleman, R. W. Lemke, M. J. Arman and L. Bowers, Phys. Rev. Lett.) 76, 154 (1996). using a 2d PIC-MCC code(J. P. Verboncoeur, A. B. Langdon and N. T. Gladd, Comp. Phys. Comm.) 87, 199 (1995).. The experimental klystron was operated as an injection-locked oscillator at 1.25-1.35 GHz, with up to 1.2 GW rms output power for a 100 ns pulse. The beam voltage was 500 kV, with current of 10 kA, and a beam pulse length of 300 ns. Simulations indicate formation of a plasma due to ionization of gases from the porous graphite collector reduces the output power, but is insufficient to fully explain the pulse shortening. In addition, mode conversion from the 3 λ / 4 mode to the λ / 4 fundamental cavity mode also occurs. Loss in the walls may attenuate the fundamental mode in the experiment. The effects of charged particle formation in the output gap, due to ionization, field emission and multipactor, are also studied. This work supported in part by AFOSR/MURI grant F49620-95-1-0253.

  1. Coronagraphy at Pic du Midi: Present state and future projects

    NASA Astrophysics Data System (ADS)

    Koechlin, L.

    2012-12-01

    The Pic du Midi coronagraph (CLIMSO) is a group of four instruments in parallel, taking images of the whole solar photosphere and low corona. It provides series of 2048*2048 pixels images taken nominally at 1 minute time intervals, all year long, weather permitting. A team of ≃q 60 persons, by groups of 2 or 3 each week, operate the instruments. Their work is programmed in collaboration with Institut de Recherches en astrophysique et planétologie (IRAP) of Observatoire Midi Pyrénées (OMP), and with Programme National Soleil Terre (PNST). The four instruments of CLIMSO (L1, C1, L2 and C2) collect images of the Sun as following: 1) L1 : photosphere in H-α (656.28 nm) ; 2) L2 : photosphere in Ca-II (393.37 nm) ; 3) C1 : prominences in H-α ; 4) C2 : prominences in He-I (1083.0 nm). The data taken are stored in fits format images and mpeg films. They are available publicly on data bases such as BASS 2000 Meudon ({http://bass2000.obspm.fr/home.php?lang=en} and BASS2000 Tarbes ({http://bass2000.bagn.obs-mip.fr/base/sun/index.php}). Several solar studies are carried in relation with these data. In addition to the raw fits images, new images will soon be sent to the data bases: they will be calibrated in solar surface emittance, expressed in W/m^2/nm/steradian. Series of mpeg films for each day are presented in superposed color layers, so as to visualize the multispectral information better. New instrumental developments are planned for the next years and already financed. They will use spectropolarimetry to measure the magnetic field and radial velocities in the photosphere and corona. The data will cover the entire solar disc and have a sample rate of one map per minute.

  2. Beta Pic-like Circumstellar Gas Disk Around 2 And

    NASA Technical Reports Server (NTRS)

    Cheng, Patricia

    2003-01-01

    This grant was awarded to support the data analysis and publication of results from our project entitled P Pic-like Circumstellar Gas Disk Around 2 And . We proposed to obtain FUSE observations of 2 And and study the characteristics and origin of its circumstellar gas. We observed 2 Andromedae with FUSE on 3-4 July 2001 in 11 exposures with a total exposure time of 21,289 seconds through the LWRS aperture. Our data were calibrated with Version 1.8.7 of the CALFUSE pipeline processing software. We corrected the wavelength scale for the heliocentric velocity error in this version of the CALFUSE software. The relative accuracy of the calibrated wavelength scale is +/- 9 km/s . We produced a co-added spectrum in the LiF 1B and LiF 2A channels (covering the 1100 to 1180 A region) by cross-correlating the 11 individual exposures and doing an exposure-time weighted average flux. The final co-added spectra have a signal-to-noise ratio in the stellar continuum near 1150 A of about 20. To obtain an absolute wavelength calibration, we cross-correlated our observed spectra with a model spectrum to obtain the best fit for the photospheric C I lines. Because the photospheric lines are very broad, this yields an absolute accuracy for the wavelength scale of approx.+/- 15 km/s. We then rebinned 5 original pixels to yield the optimal sampling of .033 A for each new pixel, because the calibrated spectra oversample the spectral resolution for FUSE+LWRS (R = 20,000 +/- 2,000).

  3. A portable approach for PIC on emerging architectures

    NASA Astrophysics Data System (ADS)

    Decyk, Viktor

    2016-03-01

    A portable approach for designing Particle-in-Cell (PIC) algorithms on emerging exascale computers, is based on the recognition that 3 distinct programming paradigms are needed. They are: low level vector (SIMD) processing, middle level shared memory parallel programing, and high level distributed memory programming. In addition, there is a memory hierarchy associated with each level. Such algorithms can be initially developed using vectorizing compilers, OpenMP, and MPI. This is the approach recommended by Intel for the Phi processor. These algorithms can then be translated and possibly specialized to other programming models and languages, as needed. For example, the vector processing and shared memory programming might be done with CUDA instead of vectorizing compilers and OpenMP, but generally the algorithm itself is not greatly changed. The UCLA PICKSC web site at http://www.idre.ucla.edu/ contains example open source skeleton codes (mini-apps) illustrating each of these three programming models, individually and in combination. Fortran2003 now supports abstract data types, and design patterns can be used to support a variety of implementations within the same code base. Fortran2003 also supports interoperability with C so that implementations in C languages are also easy to use. Finally, main codes can be translated into dynamic environments such as Python, while still taking advantage of high performing compiled languages. Parallel languages are still evolving with interesting developments in co-Array Fortran, UPC, and OpenACC, among others, and these can also be supported within the same software architecture. Work supported by NSF and DOE Grants.

  4. 1D-1D Coulomb drag in a 6 Million Mobility Bi-layer Heterostructure

    NASA Astrophysics Data System (ADS)

    Bilodeau, Simon; Laroche, Dominique; Xia, Jian-Sheng; Lilly, Mike; Reno, John; Pfeiffer, Loren; West, Ken; Gervais, Guillaume

    We report Coulomb drag measurements in vertically-coupled quantum wires. The wires are fabricated in GaAs/AlGaAs bilayer heterostructures grown from two different MBE chambers: one at Sandia National Laboratories (1.2M mobility), and the other at Princeton University (6M mobility). The previously observed positive and negative drag signals are seen in both types of devices, demonstrating the robustness of the result. However, attempts to determine the temperature dependence of the drag signal in the 1D regime proved challenging in the higher mobility heterostructure (Princeton), in part because of difficulties in aligning the wires within the same transverse subband configuration. Nevertheless, this work, performed at the Microkelvin laboratory of the University of Florida, is an important proof-of-concept for future investigations of the temperature dependence of the 1D-1D drag signal down to a few mK. Such an experiment could confirm the Luttinger charge density wave interlocking predicted to occur in the wires. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL8500.

  5. The relativist stance.

    PubMed

    Rössler, O E; Matsuno, K

    1998-04-01

    The two mindsets of absolutism and relativism are juxtaposed, and the relational or relativist stance is vindicated. The only 'absolute' entity which undeniably exists, consciousness has the reality of a dream. The escape hatch from this prison is relational, as Descartes and Levinas found out: Unfalsified relational consistency implies exteriority. Exteriority implies infinite power which in turn makes compassion inevitable. Aside from ethics as a royal way to enlightenment, a new technology called 'deep technology' may be accessible. It changes the whole world in a demonstrable fashion by manipulation of the micro frame--that is, the observer-world interface.

  6. Relativistic quantum information

    NASA Astrophysics Data System (ADS)

    Mann, R. B.; Ralph, T. C.

    2012-11-01

    Over the past few years, a new field of high research intensity has emerged that blends together concepts from gravitational physics and quantum computing. Known as relativistic quantum information, or RQI, the field aims to understand the relationship between special and general relativity and quantum information. Since the original discoveries of Hawking radiation and the Unruh effect, it has been known that incorporating the concepts of quantum theory into relativistic settings can produce new and surprising effects. However it is only in recent years that it has become appreciated that the basic concepts involved in quantum information science undergo significant revision in relativistic settings, and that new phenomena arise when quantum entanglement is combined with relativity. A number of examples illustrate that point. Quantum teleportation fidelity is affected between observers in uniform relative acceleration. Entanglement is an observer-dependent property that is degraded from the perspective of accelerated observers moving in flat spacetime. Entanglement can also be extracted from the vacuum of relativistic quantum field theories, and used to distinguish peculiar motion from cosmological expansion. The new quantum information-theoretic framework of quantum channels in terms of completely positive maps and operator algebras now provides powerful tools for studying matters of causality and information flow in quantum field theory in curved spacetimes. This focus issue provides a sample of the state of the art in research in RQI. Some of the articles in this issue review the subject while others provide interesting new results that will stimulate further research. What makes the subject all the more exciting is that it is beginning to enter the stage at which actual experiments can be contemplated, and some of the articles appearing in this issue discuss some of these exciting new developments. The subject of RQI pulls together concepts and ideas from

  7. The relativist stance.

    PubMed

    Rössler, O E; Matsuno, K

    1998-04-01

    The two mindsets of absolutism and relativism are juxtaposed, and the relational or relativist stance is vindicated. The only 'absolute' entity which undeniably exists, consciousness has the reality of a dream. The escape hatch from this prison is relational, as Descartes and Levinas found out: Unfalsified relational consistency implies exteriority. Exteriority implies infinite power which in turn makes compassion inevitable. Aside from ethics as a royal way to enlightenment, a new technology called 'deep technology' may be accessible. It changes the whole world in a demonstrable fashion by manipulation of the micro frame--that is, the observer-world interface. PMID:9648695

  8. Modeling relativistic nuclear collisions.

    SciTech Connect

    Anderlik, C.; Magas, V.; Strottman, D.; Csernai, L. P.

    2001-01-01

    Modeling Ultra-Relativistic Heavy Ion Collisioiis at RHIC and LHC energies using a Multi Module Model is presented. The first Module is the Effective String Rope Model for the calculation of the initial stages of the reaction; the output of this module is used as the initial state for the subsequent one-fluid hydrodynainical calculation module. It is shown that such an initial state leads to the creation of the third flow component. The hydrodynamical evolution of the energy density distribution is presented for RHIC energies. The final module describing the Freeze Out; and Hadronization is also discussed.

  9. Relativistic Effects on Chemical Properties.

    ERIC Educational Resources Information Center

    McKelvey, Donald R.

    1983-01-01

    Discusses how anomalous chemical properties may be explained by considering relativistic effects. Traces development of the relativistic wave equation (Dirac equation) starting with the Borh treatment of the hydrogen atom and discusses major consequences of the Dirac equation. Suggests that these topics receive greater attention in the…

  10. A Simple Relativistic Bohr Atom

    ERIC Educational Resources Information Center

    Terzis, Andreas F.

    2008-01-01

    A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…

  11. relline: Relativistic line profiles calculation

    NASA Astrophysics Data System (ADS)

    Dauser, Thomas

    2015-05-01

    relline calculates relativistic line profiles; it is compatible with the common X-ray data analysis software XSPEC (ascl:9910.005) and ISIS (ascl:1302.002). The two basic forms are an additive line model (RELLINE) and a convolution model to calculate relativistic smearing (RELCONV).

  12. Relativistic and nonrelativistic quarkonium models

    SciTech Connect

    Ono, S.

    1982-11-01

    We propose a quarkonium potential for the Klein-Gordon equation. The relativistic effects are small even for uu-bar and dd-bar systems because the introduction of a scalar constant potential in a Klein-Gordon equation allows a minimization of relativistic effects via cancellations in our model.

  13. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe.

    PubMed

    Zhang, C J; Hua, J F; Xu, X L; Li, F; Pai, C-H; Wan, Y; Wu, Y P; Gu, Y Q; Mori, W B; Joshi, C; Lu, W

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

  14. Magnetic Field Generation, Particle Energization and Radiation at Relativistic Shear Boundary Layers

    NASA Astrophysics Data System (ADS)

    Liang, Edison; Fu, Wen; Spisak, Jake; Boettcher, Markus

    2015-11-01

    Recent large scale Particle-in-Cell (PIC) simulations have demonstrated that in unmagnetized relativistic shear flows, strong transverse d.c. magnetic fields are generated and sustained by ion-dominated currents on the opposite sides of the shear interface. Instead of dissipating the shear flow free energy via turbulence formation and mixing as it is usually found in MHD simulations, the kinetic results show that the relativistic boundary layer stabilizes itself via the formation of a robust vacuum gap supported by a strong magnetic field, which effectively separates the opposing shear flows, as in a maglev train. Our new PIC simulations have extended the runs to many tens of light crossing times of the simulation box. Both the vacuum gap and supporting magnetic field remain intact. The electrons are energized to reach energy equipartition with the ions, with 10% of the total energy in electromagnetic fields. The dominant radiation mechanism is similar to that of a wiggler, due to oscillating electron orbits around the boundary layer.

  15. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    DOE PAGES

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C. -H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; et al

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of themore » wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.« less

  16. Characteristics of relativistic electron mirrors generated by an ultrashort nonadiabatic laser pulse from a nanofilm

    NASA Astrophysics Data System (ADS)

    Kulagin, Victor V.; Cherepenin, Vladimir A.; Gulyaev, Yuri V.; Kornienko, Vladimir N.; Pae, Ki Hong; Valuev, Victor V.; Lee, Jongmin; Suk, Hyyong

    2009-07-01

    For controllable generation of an isolated attosecond relativistic electron bunch [relativistic electron mirror (REM)] with nearly solid-state density, we proposed [V. V. Kulagin , Phys. Rev. Lett. 99, 124801 (2007)] to use a solid nanofilm illuminated normally by an ultraintense femtosecond laser pulse having a sharp rising edge (nonadiabatic laser pulse). In this paper, the REM characteristics are investigated in a regular way for a wide range of parameters. With the help of two-dimensional (2D) particle-in-cell (PIC) simulations, it is shown that, in spite of Coulomb forces, all of the electrons in the laser spot can be synchronously accelerated to ultrarelativistic velocities by the first half-cycle of the field, which has large enough amplitude. For the process of the REM generation, we also verify a self-consistent one-dimensional theory, which we developed earlier (cited above) and which takes into account Coulomb forces, radiation of the electrons, and laser amplitude depletion. This theory shows a good agreement with the results of the 2D PIC simulations. Finally, the scaling of the REM dynamical parameters with the field amplitude and the nanofilm thickness is analyzed.

  17. Characteristics of relativistic electron mirrors generated by an ultrashort nonadiabatic laser pulse from a nanofilm

    SciTech Connect

    Kulagin, Victor V.; Pae, Ki Hong; Lee, Jongmin; Cherepenin, Vladimir A.; Gulyaev, Yuri V.; Kornienko, Vladimir N.; Valuev, Victor V.; Suk, Hyyong

    2009-07-15

    For controllable generation of an isolated attosecond relativistic electron bunch [relativistic electron mirror (REM)] with nearly solid-state density, we proposed [V. V. Kulagin et al., Phys. Rev. Lett. 99, 124801 (2007)] to use a solid nanofilm illuminated normally by an ultraintense femtosecond laser pulse having a sharp rising edge (nonadiabatic laser pulse). In this paper, the REM characteristics are investigated in a regular way for a wide range of parameters. With the help of two-dimensional (2D) particle-in-cell (PIC) simulations, it is shown that, in spite of Coulomb forces, all of the electrons in the laser spot can be synchronously accelerated to ultrarelativistic velocities by the first half-cycle of the field, which has large enough amplitude. For the process of the REM generation, we also verify a self-consistent one-dimensional theory, which we developed earlier (cited above) and which takes into account Coulomb forces, radiation of the electrons, and laser amplitude depletion. This theory shows a good agreement with the results of the 2D PIC simulations. Finally, the scaling of the REM dynamical parameters with the field amplitude and the nanofilm thickness is analyzed.

  18. Simulation of Relativistic Shocks and Associated Radiation from Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    Using our new 3-D relativistic particle-in-cell (PIC) code, we investigated long-term particle acceleration associated with a relativistic electron-positron jet propagating in an unmagnetized ambient electron-positron plasma. The simulations were performed using a much longer simulation system than our previous simulations in order to investigate the full nonlinear stage of the Weibel instability and its particle acceleration mechanism. Cold jet electrons are thermalized and ambient electrons are accelerated in the resulting shocks. Acceleration of ambient electrons leads to a maximum ambient electron density three times larger than the original value as predicted by hydrodynamic compression. Behind the bow shock, in the jet shock, strong electromagnetic fields are generated. These fields may lead to time dependent afterglow emission. In order to go beyond the standard synchrotron model used in astrophysical objects we have used PIC simulations and calculated radiation based on first principles. We calculated radiation from electrons propagating in a uniform parallel magnetic field to verify the technique. We also used the technique to calculate emission from electrons based on simulations with a small system. We obtain spectra which are consistent with those generated from electrons propagating in turbulent magnetic fields. This turbulent magnetic field is similar to the magnetic field generated at an early nonlinear stage of the Weibel instability. A fully developed shock within a larger system may generate a jitter/synchrotron spectrum.

  19. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    PubMed Central

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C.-H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; Lu, W.

    2016-01-01

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method. PMID:27403561

  20. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    NASA Astrophysics Data System (ADS)

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C.-H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; Lu, W.

    2016-07-01

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

  1. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe.

    PubMed

    Zhang, C J; Hua, J F; Xu, X L; Li, F; Pai, C-H; Wan, Y; Wu, Y P; Gu, Y Q; Mori, W B; Joshi, C; Lu, W

    2016-01-01

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method. PMID:27403561

  2. Classification and stability of plasma motion in periodic linearly polarized relativistic waves

    SciTech Connect

    Lehmann, G.; Spatschek, K. H.

    2010-07-15

    Based on a relativistic fluid-Maxwell model, laser-induced plasma dynamics is investigated for relativistic periodic waves. Within a one-dimensional (1D) description, the Akhiezer-Polovin model is applied to the existence of periodic, nonlinearly coupled electromagnetic and electrostatic waves, and the corresponding particle motion. Known existence criteria for periodic solutions are generalized. The corresponding stability behaviors are investigated by 1D integrators of the relativistic fluid-Maxwell model. It is shown that in contrast to the vacuum solution, linearly polarized coupled electromagnetic-electrostatic waves are unstable in plasmas. The magnitudes of the growth rates are investigated in terms of the maximum amplitudes and normalized phase velocities.

  3. Relativistic Continuum Shell Model

    NASA Astrophysics Data System (ADS)

    Grineviciute, Janina; Halderson, Dean

    2011-04-01

    The R-matrix formalism of Lane and Thomas has been extended to the relativistic case so that the many-coupled channels problem may be solved for systems in which binary breakup channels satisfy a relative Dirac equation. The formalism was previously applied to the relativistic impulse approximation RIA and now we applied it to Quantum Hadrodynamics QHD in the continuum Tamm-Dancoff approximation TDA with the classical meson fields replaced by one-meson exchange potentials. None of the published QHD parameters provide a decent fit to the 15 N + p elastic cross section. The deficiency is also evident in inability of the QHD parameters with the one meson exchange potentials to reproduce the QHD single particle energies. Results with alternate parameters sets are presented. A. M. Lane and R. G. Thomas, R-Matrix Theory of Nuclear Reactions, Reviews of Modern Physics, 30 (1958) 257

  4. Stationary relativistic jets

    NASA Astrophysics Data System (ADS)

    Komissarov, Serguei S.; Porth, Oliver; Lyutikov, Maxim

    2015-11-01

    In this paper we describe a simple numerical approach which allows to study the structure of steady-state axisymmetric relativistic jets using one-dimensional time-dependent simulations. It is based on the fact that for narrow jets with vz≈ c the steady-state equations of relativistic magnetohydrodynamics can be accurately approximated by the one-dimensional time-dependent equations after the substitution z=ct. Since only the time-dependent codes are now publicly available this is a valuable and efficient alternative to the development of a high-specialised code for the time-independent equations. The approach is also much cheaper and more robust compared to the relaxation method. We tested this technique against numerical and analytical solutions found in literature as well as solutions we obtained using the relaxation method and found it sufficiently accurate. In the process, we discovered the reason for the failure of the self-similar analytical model of the jet reconfinement in relatively flat atmospheres and elucidated the nature of radial oscillations of steady-state jets.

  5. A relativistic trolley paradox

    NASA Astrophysics Data System (ADS)

    Matvejev, Vadim N.; Matvejev, Oleg V.; Grøn, Ø.

    2016-06-01

    We present an apparent paradox within the special theory of relativity, involving a trolley with relativistic velocity and its rolling wheels. Two solutions are given, both making clear the physical reality of the Lorentz contraction, and that the distance on the rails between each time a specific point on the rim touches the rail is not equal to 2 π R , where R is the radius of the wheel, but 2 π R / √{ 1 - R 2 Ω 2 / c 2 } , where Ω is the angular velocity of the wheels. In one solution, the wheel radius is constant as the velocity of the trolley increases, and in the other the wheels contract in the radial direction. We also explain two surprising facts. First that the shape of a rolling wheel is elliptical in spite of the fact that the upper part of the wheel moves faster than the lower part, and thus is more Lorentz contracted, and second that a Lorentz contracted wheel with relativistic velocity rolls out a larger distance between two successive touches of a point of the wheel on the rails than the length of a circle with the same radius as the wheels.

  6. Relativistic harmonic oscillator revisited

    SciTech Connect

    Bars, Itzhak

    2009-02-15

    The familiar Fock space commonly used to describe the relativistic harmonic oscillator, for example, as part of string theory, is insufficient to describe all the states of the relativistic oscillator. We find that there are three different vacua leading to three disconnected Fock sectors, all constructed with the same creation-annihilation operators. These have different spacetime geometric properties as well as different algebraic symmetry properties or different quantum numbers. Two of these Fock spaces include negative norm ghosts (as in string theory), while the third one is completely free of ghosts. We discuss a gauge symmetry in a worldline theory approach that supplies appropriate constraints to remove all the ghosts from all Fock sectors of the single oscillator. The resulting ghost-free quantum spectrum in d+1 dimensions is then classified in unitary representations of the Lorentz group SO(d,1). Moreover, all states of the single oscillator put together make up a single infinite dimensional unitary representation of a hidden global symmetry SU(d,1), whose Casimir eigenvalues are computed. Possible applications of these new results in string theory and other areas of physics and mathematics are briefly mentioned.

  7. Relativistic Iron Line Fits

    NASA Astrophysics Data System (ADS)

    Fink, M.; Dauser, T.; Beuchert, T.; Jeffreson, S.; Tawabutr, J.; Wilms, J.; García, J.; Walton, D. J.

    2016-08-01

    The 6.4 keV Iron reflection line possesses strong diagnostic potential for AGN-systems. In the rare case of unobscured AGN, this line receives a contribution from the very center of the accretion flow close to the event horizon that is subject to strong relativistic effects. The shape of this line distortion can be used infer important parameters of the central accretion region, especially the black hole spin parameter a* and the accretion disk inclination i. We analyze several (nine?) bare AGN spectra from the sample of Walton et al. 2012 using high resolution spectra from the XMM and NuStar archives. The relativistic reflection is modeled using the RELXILL code (Dauser 20XX). The newest iteration of the RELXILL model also supports a lamp post geometry for the irradiation of the accretion disk. By combining these detailed models with the wide spectral range of NuStar and XMM/NuStar joint observations we can put tight constraints on the aforementioned parameters and we can constrain the height of the source h in a possible lamp post geometry.

  8. PIC simulations on the termination shock: Microstructure and electron acceleration

    NASA Astrophysics Data System (ADS)

    Matsukiyo, S.; Scholer, M.

    2013-05-01

    The ability of the termination shock as a particle accelerator is totally unknown. Voyager data and recent kinetic numerical simulations revealed that the compression ratio of the termination shock is rather low due to the presence of pickup ions, i.e., the termination shock appears to be a weak shock. Nevertheless, two Voyager spacecraft observed not only high energy ions called termination shock particles, which are non-thermal but less energetic compared to the so-called anomalous cosmic rays, but also high energy electrons. In this study we focus especially on microstructure of the termination shock and the associated electron acceleration process by performing one-dimensional full particle-in-cell (PIC) simulations for a variety of parameters. For typical solar wind parameters at the termination shock, a shock potential has no sharp ramp with the spatial scale of the order of electron inertial length which is suitable for the injection of anomalous cosmic ray acceleration. Solar wind ions are not so much heated, which is consistent with Voyager spacecraft data. If a shock angle is close to 90 deg., a shock is almost time stationary or weakly breathing when a relative pickup ion density is 30%, while it becomes non-stationary if the relative pickup ion density is 20%. When the shock angle becomes oblique, a self-reformation occurs due to the interaction of solar wind ions and whistler precursors. Here, the shock angle is defined as the angle between upstream magnetic field and shock normal. For the case with relatively low beta solar wind plasma (electron beta is 0.1 and solar wind ion temperature equals to electron temperature), modified two-stream instability (MTSI) gets excited in the extended foot sustained by reflected pickup ions, and both solar wind electrons and ions are heated. If the solar wind plasma temperature gets five times higher, on the other hand, the MTSI is weakened and the pre-heating of the solar wind plasma in the extended foot is

  9. On specular reflectivity measurements in high and low-contrast relativistic laser-plasma interactions

    SciTech Connect

    Kemp, G. E.; Link, A.; Ping, Y.; McLean, H. S.; Patel, P. K.; Freeman, R. R.; Schumacher, D. W.; Tiedje, H. F.; Tsui, Y. Y.; Fedosejevs, R.; Ramis, R.

    2015-01-15

    Using both experiment and 2D3V particle-in-cell (PIC) simulations, we describe the use of specular reflectivity measurements to study relativistic (Iλ{sup 2 }> 10{sup 18 }W/cm{sup 2}⋅μm{sup 2}) laser-plasma interactions for both high and low-contrast 527 nm laser pulses on initially solid density aluminum targets. In the context of hot-electron generation, studies typically rely on diagnostics which, more-often-than-not, represent indirect processes driven by fast electrons transiting through solid density materials. Specular reflectivity measurements, however, can provide a direct measure of the interaction that is highly sensitive to how the EM fields and plasma profiles, critical input parameters for modeling of hot-electron generation, evolve near the interaction region. While the fields of interest occur near the relativistic critical electron density, experimental reflectivity measurements are obtained centimeters away from the interaction region, well after diffraction has fully manifested itself. Using a combination of PIC simulations with experimentally inspired conditions and an analytic, non-paraxial, pulse propagation algorithm, we calculate reflected pulse properties, both near and far from the interaction region, and compare with specular reflectivity measurements. The experiment results and PIC simulations demonstrate that specular reflectivity measurements are an extremely sensitive qualitative, and partially quantitative, indicator of initial laser/target conditions, ionization effects, and other details of intense laser-matter interactions. The techniques described can provide strong constraints on many systems of importance in ultra-intense laser interactions with matter.

  10. Relativistic fluid formulation and theory of intense relativistic electron beams

    SciTech Connect

    Siambis, J.G.

    1984-01-01

    A new general relativistic fluid formulation has been obtained for intense relativistic electron beams (IREB) with arbitrarily high relativistic mass factor ..gamma... This theory is valid for confined IREB equilibria such as those found inside high energy accelerators as well as in the pinched and ion-focused regimes of beam propagation in plasma channels. The new relativistic fluid formulation is based on the covariant relativistic fluid formulation of Newcomb with the parameter lambda identical to 1, in order to allow for realistic confined equilibria. The resulting equilibrium constraints require that the beam has a slow rotational velocity around its direction of propagation and that the off-diagonal thermal stress element, associated with these two directions of motion, be nonzero. The effective betatron oscillation frequency of the fluid elements of the beam is modified by the radial gradient and anisotropies in the thermal stress elements of the beam fluid. The wave equation, for sausage, hose and filamentation excitations on the relativistic fluid beam, is found to be formally identical to that obtained from the Vlasov equation approach, hence phase-mixing damping is a generic and self-consistent correlate of the new relativistic fluid formulation.

  11. Human serotonin 1D receptor is encoded by a subfamily of two distinct genes: 5-HT1D alpha and 5-HT1D beta.

    PubMed Central

    Weinshank, R L; Zgombick, J M; Macchi, M J; Branchek, T A; Hartig, P R

    1992-01-01

    The serotonin 1D (5-HT1D) receptor is a pharmacologically defined binding site and functional receptor site. Observed variations in the properties of 5-HT1D receptors in different tissues have led to the speculation that multiple receptor proteins with slightly different properties may exist. We report here the cloning, deduced amino acid sequences, pharmacological properties, and second-messenger coupling of a pair of human 5-HT1D receptor genes, which we have designated 5-HT1D alpha and 5-HT1D beta due to their strong similarities in sequence, pharmacological properties, and second-messenger coupling. Both genes are free of introns in their coding regions, are expressed in the human cerebral cortex, and can couple to inhibition of adenylate cyclase activity. The pharmacological binding properties of these two human receptors are very similar, and match closely the pharmacological properties of human, bovine, and guinea pig 5-HT1D sites. Both receptors exhibit high-affinity binding of sumatriptan, a new anti-migraine medication, and thus are candidates for the pharmacological site of action of this drug. Images PMID:1565658

  12. Forced Reconnection in the Near Magnetotail: Onset and Energy Conversion in PIC and MHD Simulations

    NASA Technical Reports Server (NTRS)

    Birn, J.; Hesse, Michael

    2014-01-01

    Using two-dimensional particle-in-cell (PIC) together with magnetohydrodynamic (MHD) Q1 simulations of magnetotail dynamics, we investigate the evolution toward onset of reconnection and the subsequent energy transfer and conversion. In either case, reconnection onset is preceded by a driven phase, during which magnetic flux is added to the tail at the high-latitude boundaries, followed by a relaxation phase, during which the configuration continues to respond to the driving. The boundary deformation leads to the formation of thin embedded current sheets, which are bifurcated in the near tail, converging to a single sheet farther out in the MHD simulations. The thin current sheets in the PIC simulation are carried by electrons and are associated with a strong perpendicular electrostatic field, which may provide a connection to parallel potentials and auroral arcs and an ionospheric signal even prior to the onset of reconnection. The PIC simulation very well satisfies integral entropy conservation (intrinsic to ideal MHD) during this phase, supporting ideal ballooning stability. Eventually, the current intensification leads to the onset of reconnection, the formation and ejection of a plasmoid, and a collapse of the inner tail. The earthward flow shows the characteristics of a dipolarization front: enhancement of Bz, associated with a thin vertical electron current sheet in the PIC simulation. Both MHD and PIC simulations show a dominance of energy conversion from incoming Poynting flux to outgoing enthalpy flux, resulting in heating of the inner tail. Localized Joule dissipation plays only a minor role.

  13. A portable platform for accelerated PIC codes and its application to GPUs using OpenACC

    NASA Astrophysics Data System (ADS)

    Hariri, F.; Tran, T. M.; Jocksch, A.; Lanti, E.; Progsch, J.; Messmer, P.; Brunner, S.; Gheller, C.; Villard, L.

    2016-10-01

    We present a portable platform, called PIC_ENGINE, for accelerating Particle-In-Cell (PIC) codes on heterogeneous many-core architectures such as Graphic Processing Units (GPUs). The aim of this development is efficient simulations on future exascale systems by allowing different parallelization strategies depending on the application problem and the specific architecture. To this end, this platform contains the basic steps of the PIC algorithm and has been designed as a test bed for different algorithmic options and data structures. Among the architectures that this engine can explore, particular attention is given here to systems equipped with GPUs. The study demonstrates that our portable PIC implementation based on the OpenACC programming model can achieve performance closely matching theoretical predictions. Using the Cray XC30 system, Piz Daint, at the Swiss National Supercomputing Centre (CSCS), we show that PIC_ENGINE running on an NVIDIA Kepler K20X GPU can outperform the one on an Intel Sandy bridge 8-core CPU by a factor of 3.4.

  14. Parallel Higher-order Finite Element Method for Accurate Field Computations in Wakefield and PIC Simulations

    SciTech Connect

    Candel, A.; Kabel, A.; Lee, L.; Li, Z.; Limborg, C.; Ng, C.; Prudencio, E.; Schussman, G.; Uplenchwar, R.; Ko, K.; /SLAC

    2009-06-19

    Over the past years, SLAC's Advanced Computations Department (ACD), under SciDAC sponsorship, has developed a suite of 3D (2D) parallel higher-order finite element (FE) codes, T3P (T2P) and Pic3P (Pic2P), aimed at accurate, large-scale simulation of wakefields and particle-field interactions in radio-frequency (RF) cavities of complex shape. The codes are built on the FE infrastructure that supports SLAC's frequency domain codes, Omega3P and S3P, to utilize conformal tetrahedral (triangular)meshes, higher-order basis functions and quadratic geometry approximation. For time integration, they adopt an unconditionally stable implicit scheme. Pic3P (Pic2P) extends T3P (T2P) to treat charged-particle dynamics self-consistently using the PIC (particle-in-cell) approach, the first such implementation on a conformal, unstructured grid using Whitney basis functions. Examples from applications to the International Linear Collider (ILC), Positron Electron Project-II (PEP-II), Linac Coherent Light Source (LCLS) and other accelerators will be presented to compare the accuracy and computational efficiency of these codes versus their counterparts using structured grids.

  15. GaAs Photonic Integrated Circuit (PIC) development for high performance communications

    SciTech Connect

    Sullivan, C.T.

    1998-03-01

    Sandia has established a foundational technology in photonic integrated circuits (PICs) based on the (Al,Ga,In)As material system for optical communication, radar control and testing, and network switching applications at the important 1.3{mu}m/1.55{mu}m wavelengths. We investigated the optical, electrooptical, and microwave performance characteristics of the fundamental building-block PIC elements designed to be as simple and process-tolerant as possible, with particular emphasis placed on reducing optical insertion loss. Relatively conventional device array and circuit designs were built using these PIC elements: (1) to establish a baseline performance standard; (2) to assess the impact of epitaxial growth accuracy and uniformity, and of fabrication uniformity and yield; (3) to validate our theoretical and numerical models; and (4) to resolve the optical and microwave packaging issues associated with building fully packaged prototypes. Novel and more complex PIC designs and fabrication processes, viewed as higher payoff but higher risk, were explored in a parallel effort with the intention of meshing those advances into our baseline higher-yield capability as they mature. The application focus targeted the design and fabrication of packaged solitary modulators meeting the requirements of future wideband and high-speed analog and digital data links. Successfully prototyped devices are expected to feed into more complex PICs solving specific problems in high-performance communications, such as optical beamforming networks for phased array antennas.

  16. Percutaneous intragastric catheter (PIC) for administration of an unpalatable substance to large animals.

    PubMed

    Oleszczuk, Agnieszka; Spannbauer, Michael M; Bluher, Matthias; Ott, Rudolf; Pietsch, Uta-Carolin; Schneider, Katja; Madaj-Sterba, Petra; Furll, Manfred; Hauss, Johann P; Schön, Michael R

    2009-01-01

    We studied an easy and reliable technique for administration of an unpalatable substance to large animals. There were three groups of pigs: group I (n = 6) received 1 g ethanol/kg body weight per day orally with water for 24 days, group II (n = 6) received 2 g ethanol/kg orally with water for 24 days and 4 g ethanol/kg via percutaneous intragastric catheter (PIC) for the next 24 days, group III (n = 6) received 6 g ethanol/kg via PIC for 72 days. The catheter was placed after insufflation of the stomach using an orogastric tube. PIC was successfully placed in each pig. No complications occurred during placement. The total amount of the administrated dose was assimilated each time. PIC is a safe, effective, well tolerated, and precise method of administering ethanol that is inexpensive and easy to perform. Ethanol administration via PIC is a convenient and effective mean of exposing animals to high levels of alcohol on a long-term basis.

  17. PlasmaPIC: A tool for modeling low-temperature plasma discharges

    NASA Astrophysics Data System (ADS)

    Muehlich, Nina Sarah; Becker, Michael; Henrich, Robert; Heiliger, Christian

    2015-09-01

    PlasmaPIC is a three-dimensional particle in cell (PIC) code. It consists of an electrostatic part for modeling dc and rf-ccp discharges as well as an electrodynamic part for modeling inductively coupled discharges. The three-dimensional description enables the modeling of discharges in arbitrary geometries without limitations to any symmetry. These geometries can be easily imported from common CAD tools. A main feature of PlasmaPIC is the ability of an excellent massive parallelization of the computation, which scales linearly up to a few hundred cpu cores. This is achieved by using a multigrid algorithm for the field solver as well as an effective load balancing of the particles. Moreover, PlasmaPIC includes the interaction of the neutral gas and the plasma discharge. Because the neutral gas and the plasma simulation are acting on different time scales we perform the simulation of both separately in a self-consistent treatment, whereas the neutral gas distribution is calculated using the direct simulation Monte Carlo method (DSMC). The merge of these features turns PlasmaPIC into a powerful simulation tool for a wide range of plasma discharges and introduces a new way of understanding and optimizing low-temperature plasma applications. This work has been supported by the ``Bundesministerium fuer Wirtschaft und Energie.'' Grant 50RS1507.

  18. Characterization of PIC emissions from combustion of pentachlorophenol-treated wood wastes

    SciTech Connect

    Lee, S.Y.; Valenti, J.C.; Tabor, D.G.

    1997-12-01

    The use of waste wood as fuel for producing energy is a promising supplement to fossil fuels for many regions of the country. In addition to recovering energy and conserving landfill space, burning waste wood fuels also mitigates global warming created by fossil fuel combustion. However, the environmental consequences resulting from emissions generated by combustion of waste wood which contains paints, resins, or preservatives are not well understood. The combustion of waste wood treated with chemicals may produce potentially hazardous products of incomplete combustion (PIC) emissions such as dioxins. Characterization of PIC emissions from the combustion of waste wood previously treated with pentachlorophenol is reported in this study. Utility poles and crossbars are typically treated with a preservative such as pentachlorophenol in order to prolong their service life. They are disposed of by landfilling after being taken out of service. Burning such wood waste in boilers for steam generation becomes an increasingly attractive waste management alternative as it contains substantial energy value and reduces landfilling costs. Pilot-scale combustion tests were conducted under well controlled conditions in a 0.58 MW (2 million Btu/hr) combustor to compare PIC emissions from burning untreated wood and pentachlorophenol-treated wood. Sampling and analyses for a wide variety of PICs, including volatile organic compounds (VOCs), semivolatile organic compounds, and dioxins and furans, were performed to assess the effect of pentachlorophenol preservative present in wood on PIC emissions.

  19. Pic, an Autotransporter Protein Secreted by Different Pathogens in the Enterobacteriaceae Family, Is a Potent Mucus Secretagogue▿

    PubMed Central

    Navarro-Garcia, Fernando; Gutierrez-Jimenez, Javier; Garcia-Tovar, Carlos; Castro, Luis A.; Salazar-Gonzalez, Hector; Cordova, Vanessa

    2010-01-01

    A hallmark of enteroaggregative Escherichia coli (EAEC) infection is a formation of biofilm, which comprises a mucus layer with immersed bacteria in the intestines of patients. While studying the mucinolytic activity of Pic in an in vivo system, rat ileal loops, we surprisingly found that EAEC induced hypersecretion of mucus, which was accompanied by an increase in the number of mucus-containing goblet cells. Interestingly, an isogenic pic mutant (EAEC Δpic) was unable to cause this mucus hypersecretion. Furthermore, purified Pic was also able to induce intestinal mucus hypersecretion, and this effect was abolished when Pic was heat denatured. Site-directed mutagenesis of the serine protease catalytic residue of Pic showed that, unlike the mucinolytic activity, secretagogue activity did not depend on this catalytic serine protease motif. Other pathogens harboring the pic gene, such as Shigella flexneri and uropathogenic E. coli (UPEC), also showed results similar to those for EAEC, and construction of isogenic pic mutants of S. flexneri and UPEC confirmed this secretagogue activity. Thus, Pic mucinase is responsible for one of the pathophysiologic features of the diarrhea mediated by EAEC and the mucoid diarrhea induced by S. flexneri. PMID:20696826

  20. Pic, an autotransporter protein secreted by different pathogens in the Enterobacteriaceae family, is a potent mucus secretagogue.

    PubMed

    Navarro-Garcia, Fernando; Gutierrez-Jimenez, Javier; Garcia-Tovar, Carlos; Castro, Luis A; Salazar-Gonzalez, Hector; Cordova, Vanessa

    2010-10-01

    A hallmark of enteroaggregative Escherichia coli (EAEC) infection is a formation of biofilm, which comprises a mucus layer with immersed bacteria in the intestines of patients. While studying the mucinolytic activity of Pic in an in vivo system, rat ileal loops, we surprisingly found that EAEC induced hypersecretion of mucus, which was accompanied by an increase in the number of mucus-containing goblet cells. Interestingly, an isogenic pic mutant (EAEC Δpic) was unable to cause this mucus hypersecretion. Furthermore, purified Pic was also able to induce intestinal mucus hypersecretion, and this effect was abolished when Pic was heat denatured. Site-directed mutagenesis of the serine protease catalytic residue of Pic showed that, unlike the mucinolytic activity, secretagogue activity did not depend on this catalytic serine protease motif. Other pathogens harboring the pic gene, such as Shigella flexneri and uropathogenic E. coli (UPEC), also showed results similar to those for EAEC, and construction of isogenic pic mutants of S. flexneri and UPEC confirmed this secretagogue activity. Thus, Pic mucinase is responsible for one of the pathophysiologic features of the diarrhea mediated by EAEC and the mucoid diarrhea induced by S. flexneri.

  1. Notes on Lycocerus kiontochananus (Pic, 1921) and description of two new species of Lycocerus Gorham from China (Coleoptera, Cantharidae).

    PubMed

    Yang, Yuxia; Yang, Xingke

    2014-03-11

    The Lycocerus kiontochananus species complex is revised; L. perroudi (Pic, 1937) stat. rev., originally in Cantharis, is resurrected from synonymy with L. kiontochananus (Pic, 1921); L. atropygidialis (Pic, 1937) stat. nov., originally in Cantharis, is upgraded from Cantharis perroudi var. atropygidialis Pic, 1937 and resurrected from synonymy with L. kiontochananus; L. kejvali Švihla, 2004 syn. nov. is considered as a junior synonym with L. kiontochananus. The male of L. perroudi and the female of L. jendeki Švihla, 2005 are described for the first time. Two new species are described under the names of L. metalliceps sp. nov. (China: Sichuan) and L. hainanus sp. nov. (China: Hainan).

  2. Relativistic Quantum Cryptography

    NASA Astrophysics Data System (ADS)

    Jeffrey, Evan; Kwiat, Paul

    2006-03-01

    We present results from a relativistic quantum cryptography system which uses photon storage to avoid bit sifting, in principle doubling the useful key rate. Bob stores the photon he receives from Alice in an optical delay line until she sends him the classical basis information, allowing him to measure every photon in the correct basis. Accounting for loss in our 489-ns storage cavity, we achieve a 66% increase in the BB84 key rate. The same system could be used for even greater gains in either the six-state protocol or cryptography using a larger Hilbert space. We show that the security of this protocol is equivalent to standard BB84: assuming the quantum and classical signals are space-like separated, no eavesdropper bound by special relativity can access both simultaneously.

  3. Modelling early stages of relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Ruggieri, M.; Puglisi, A.; Oliva, L.; Plumari, S.; Scardina, F.; Greco, V.

    2016-05-01

    In this study we model early time dynamics of relativistic heavy ion collisions by an initial color-electric field which then decays to a plasma by the Schwinger mechanism. The dynamics of the many particles system produced by the decay is described by relativistic kinetic theory, taking into account the backreaction on the color field by solving self-consistently the kinetic and the field equations. Our main results concern isotropization and thermalization for a 1+1D expanding geometry. In case of small η/s (η/s ≲ 0.3) we find τisotropization ≈ 0.8 fm/c and τthermalization ≈ 1 fm/c in agreement with the common lore of hydrodynamics.

  4. Relativistic Runaway Electrons

    NASA Astrophysics Data System (ADS)

    Breizman, Boris

    2014-10-01

    This talk covers recent developments in the theory of runaway electrons in a tokamak with an emphasis on highly relativistic electrons produced via the avalanche mechanism. The rapidly growing population of runaway electrons can quickly replace a large part of the initial current carried by the bulk plasma electrons. The magnetic energy associated with this current is typically much greater than the particle kinetic energy. The current of a highly relativistic runaway beam is insensitive to the particle energy, which separates the description of the runaway current evolution from the description of the runaway energy spectrum. A strongly anisotropic distribution of fast electrons is generally prone to high-frequency kinetic instabilities that may cause beneficial enhancement of runaway energy losses. The relevant instabilities are in the frequency range of whistler waves and electron plasma waves. The instability thresholds reported in earlier work have been revised considerably to reflect strong dependence of collisional damping on the wave frequency and the role of plasma non-uniformity, including radial trapping of the excited waves in the plasma. The talk also includes a discussion of enhanced scattering of the runaways as well as the combined effect of enhanced scattering and synchrotron radiation. A noteworthy feature of the avalanche-produced runaway current is a self-sustained regime of marginal criticality: the inductive electric field has to be close to its critical value (representing avalanche threshold) at every location where the runaway current density is finite, and the current density should vanish at any point where the electric field drops below its critical value. This nonlinear Ohm's law enables complete description of the evolving current profile. Work supported by the U.S. Department of Energy Contract No. DEFG02-04ER54742 and by ITER contract ITER-CT-12-4300000273. The views and opinions expressed herein do not necessarily reflect those of

  5. Some problems in relativistic thermodynamics

    SciTech Connect

    Veitsman, E. V.

    2007-11-15

    The relativistic equations of state for ideal and real gases, as well as for various interface regions, have been derived. These dependences help to eliminate some controversies in the relativistic thermodynamics based on the special theory of relativity. It is shown, in particular, that the temperature of system whose velocity tends to the velocity of light in vacuum varies in accordance with the Ott law T = T{sub 0}/{radical}1 - v{sup 2}/c{sup 2}. Relativistic dependences for heat and mass transfer, for Ohm's law, and for a viscous flow of a liquid have also been derived.

  6. picA, a novel plant-inducible locus on the Agrobacterium tumefaciens chromosome.

    PubMed Central

    Rong, L; Karcher, S J; O'Neal, K; Hawes, M C; Yerkes, C D; Jayaswal, R K; Hallberg, C A; Gelvin, S B

    1990-01-01

    We used the transposon Mu dI1681 to identify genes on the Agrobacterium tumefaciens chromosome that are inducible by extracts from carrot roots. One such locus (picA, for plant inducible chromosomal), harbored by A. tumefaciens At156, was inducible 10- to 50-fold by these extracts. Mutation of picA had no detectable effect upon bacterial growth or virulence under laboratory assay conditions. However, A. tumefaciens cells harboring a mutated picA locus aggregated into long "ropes" when incubated with pea root tip cells. Such aggregation was not displayed by the parental strain A. tumefaciens A136. A preliminary characterization of the inducing compound in the carrot root extract suggests that the active substance is an acidic polysaccharide that is most likely derived from the pectic portion of the plant cell wall. Images PMID:2170328

  7. Saltwell PIC Skid Programmable Logic Controller (PLC) Software Configuration Management Plan

    SciTech Connect

    KOCH, M.R.

    1999-11-16

    This document provides the procedures and guidelines necessary for computer software configuration management activities during the operation and maintenance phases of the Saltwell PIC Skids as required by LMH-PRO-309, Rev. 0, Computer Software Quality Assurance, Section 2.6, Software Configuration Management. The software configuration management plan (SCMP) integrates technical and administrative controls to establish and maintain technical consistency among requirements, physical configuration, and documentation for the Saltwell PIC Skid Programmable Logic Controller (PLC) software during the Hanford application, operations and maintenance. This SCMP establishes the Saltwell PIC Skid PLC Software Baseline, status changes to that baseline, and ensures that software meets design and operational requirements and is tested in accordance with their design basis.

  8. EFFECT OF INTERACTING RAREFACTION WAVES ON RELATIVISTICALLY HOT JETS

    SciTech Connect

    Matsumoto, Jin; Shibata, Kazunari; Masada, Youhei

    2012-06-01

    The effect of rarefaction acceleration on the propagation dynamics and structure of relativistically hot jets is studied through relativistic hydrodynamic simulations. We emphasize the nonlinear interaction of rarefaction waves excited at the interface between a cylindrical jet and the surrounding medium. From simplified one-dimensional (1D) models with radial jet structure, we find that a decrease in the relativistic pressure due to the interacting rarefaction waves in the central zone of the jet transiently yields a more powerful boost of the bulk jet than that expected from single rarefaction acceleration. This leads to a cyclic in situ energy conversion between thermal and bulk kinetic energies, which induces radial oscillating motion of the jet. The oscillation timescale is characterized by the initial pressure ratio of the jet to the ambient medium and follows a simple scaling relation, {tau}{sub oscillation}{proportional_to}(P{sub jet,0}/P{sub amb,0}){sup 1/2}. Extended two-dimensional simulations confirm that this radial oscillating motion in the 1D system manifests as modulation of the structure of the jet in a more realistic situation where a relativistically hot jet propagates through an ambient medium. We find that when the ambient medium has a power-law pressure distribution, the size of the reconfinement region along the propagation direction of the jet in the modulation structure {lambda} evolves according to a self-similar relation {lambda}{proportional_to}t{sup {alpha}/2}, where {alpha} is the power-law index of the pressure distribution.

  9. The chloroplast permease PIC1 regulates plant growth and development by directing homeostasis and transport of iron.

    PubMed

    Duy, Daniela; Stübe, Roland; Wanner, Gerhard; Philippar, Katrin

    2011-04-01

    The membrane-spanning protein PIC1 (for permease in chloroplasts 1) in Arabidopsis (Arabidopsis thaliana) was previously described to mediate iron transport across the inner envelope membrane of chloroplasts. The albino phenotype of pic1 knockout mutants was reminiscent of iron-deficiency symptoms and characterized by severely impaired plastid development and plant growth. In addition, plants lacking PIC1 showed a striking increase in chloroplast ferritin clusters, which function in protection from oxidative stress by sequestering highly reactive free iron in their spherical protein shell. In contrast, PIC1-overexpressing lines (PIC1ox) in this study rather resembled ferritin loss-of-function plants. PIC1ox plants suffered from oxidative stress and leaf chlorosis, most likely originating from iron overload in chloroplasts. Later during growth, plants were characterized by reduced biomass as well as severely defective flower and seed development. As a result of PIC1 protein increase in the inner envelope membrane of plastids, flower tissue showed elevated levels of iron, while the content of other transition metals (copper, zinc, manganese) remained unchanged. Seeds, however, specifically revealed iron deficiency, suggesting that PIC1 overexpression sequestered iron in flower plastids, thereby becoming unavailable for seed iron loading. In addition, expression of genes associated with metal transport and homeostasis as well as photosynthesis was deregulated in PIC1ox plants. Thus, PIC1 function in plastid iron transport is closely linked to ferritin and plastid iron homeostasis. In consequence, PIC1 is crucial for balancing plant iron metabolism in general, thereby regulating plant growth and in particular fruit development.

  10. High temperature decreases the PIC / POC ratio and increases phosphorus requirements in Coccolithus pelagicus (Haptophyta)

    NASA Astrophysics Data System (ADS)

    Gerecht, A. C.; Šupraha, L.; Edvardsen, B.; Probert, I.; Henderiks, J.

    2014-07-01

    Rising ocean temperatures will likely increase stratification of the water column and reduce nutrient input into the photic zone. This will increase the likelihood of nutrient limitation in marine microalgae, leading to changes in the abundance and composition of phytoplankton communities, which in turn will affect global biogeochemical cycles. Calcifying algae, such as coccolithophores, influence the carbon cycle by fixing CO2 into particulate organic carbon through photosynthesis (POC production) and into particulate inorganic carbon through calcification (PIC production). As calcification produces a net release of CO2, the ratio of PIC to POC production determines whether coccolithophores act as a source (high PIC / POC) or a sink (low PIC / POC) of atmospheric CO2. We studied the effect of phosphorus (P-) limitation and high temperature on the physiology and the PIC / POC ratio of two subspecies of Coccolithus pelagicus. This large and heavily calcified species is a major contributor to calcite export from the photic zone into deep-sea reservoirs. Phosphorus limitation did not influence exponential growth rates in either subspecies, but P-limited cells had significantly lower cellular P-content. One of the subspecies was subjected to a 5 °C temperature increase from 10 °C to 15 °C, which did not affect exponential growth rates either, but nearly doubled cellular P-content under both high and low phosphate availability. This temperature increase reduced the PIC / POC ratio by 40-60%, whereas the PIC / POC ratio did not differ between P-limited and nutrient-replete cultures when the subspecies were grown near their respective isolation temperature. Both P-limitation and elevated temperature significantly increased coccolith malformations. Our results suggest that a temperature increase may intensify P-limitation due to a higher P-requirement to maintain growth and POC production rates, possibly reducing abundances in a warmer ocean. Under such a scenario C

  11. Examples of Comet-like Spectra among Beta Pic-like Stars

    NASA Technical Reports Server (NTRS)

    Butner, H. M.; Walker, H. J.; Wooden, D. H.; Witteborn, F. C.

    1996-01-01

    Beta Pic is a nearby main-sequence star with an extended dust disk, large infrared excess, and mid-infrared emission similar to that seen in some cometary spectra. We selected a sample of stars whose infrared properties resemble Beta Pic and obtained 8 to 13 micron spectra (resolution 200). We find a variety of silicate emission features among the stars in our sample, ranging from classic interstellar dust features to spectra similar to that of comet P/Halley and the laboratory spectra of Interplanetary Dust Particles (IDP's).

  12. Moment preserving adaptive particle weights using octree velocity distributions for PIC simulations

    SciTech Connect

    Martin, Robert Scott; Cambier, Jean-Luc

    2012-11-27

    The ratio of computational to physical particles is of primary concern to statistical particle based simulations such as DSMC and PIC. An adaptive computational particle weight algorithm is presented that conserves mass, momentum, and energy. This algorithm is then enhanced with an octree adaptive mesh in velocity space to mitigate artificial thermalization. The new octree merge is compared to a merge that randomly selects merge partners for a bi-Maxwellian velocity distribution. Results for crossing beams in a fixed potential well along with an electrostatic PIC version with and without MCC collisions based ionizing breakdown show the advantages of the merge algorithm to both fixed particle weights and randomly selected merge partners.

  13. Relativistic spectra of bound fermions

    SciTech Connect

    Giachetti, Riccardo; Sorace, Emanuele

    2007-02-27

    A two fermion relativistic invariant wave equation is used for numerical calculations of the hyperfine shifts of the Positronium levels in a Breit interaction scheme. The results agree with known data up to the order {alpha}4.

  14. Simulating relativistic binaries with Whisky

    NASA Astrophysics Data System (ADS)

    Baiotti, L.

    We report about our first tests and results in simulating the last phase of the coalescence and the merger of binary relativistic stars. The simulations were performed using our code Whisky and mesh refinement through the Carpet driver.

  15. Relativistic Transformation of Solid Angle.

    ERIC Educational Resources Information Center

    McKinley, John M.

    1980-01-01

    Rederives the relativistic transformations of light intensity from compact sources (stars) to show where and how the transformation of a solid angle contributes. Discusses astrophysical and other applications of the transformations. (Author/CS)

  16. Conductivity of a relativistic plasma

    SciTech Connect

    Braams, B.J.; Karney, C.F.F.

    1989-03-01

    The collision operator for a relativistic plasma is reformulated in terms of an expansion in spherical harmonics. This formulation is used to calculate the electrical conductivity. 13 refs., 1 fig., 1 tab.

  17. Scattering in Relativistic Particle Mechanics.

    NASA Astrophysics Data System (ADS)

    de Bievre, Stephan

    The problem of direct interaction in relativistic particle mechanics has been extensively studied and a variety of models has been proposed avoiding the conclusions of the so-called no-interaction theorems. In this thesis we study scattering in the relativistic two-body problem. We use our results to analyse gauge invariance in Hamiltonian constraint models and the uniqueness of the symplectic structure in manifestly covariant relativistic particle mechanics. We first present a general geometric framework that underlies approaches to relativistic particle mechanics. This permits a model-independent and geometric definition of the notions of asymptotic completeness and of Moller and scattering operators. Subsequent analysis of these concepts divides into two parts. First, we study the kinematic properties of the scattering transformation, i.e. those properties that arise solely from the invariance of the theory under the Poincare group. We classify all canonical (symplectic) scattering transformations on the relativistic phase space for two free particles in terms of a single function of the two invariants of the theory. We show how this function is determined by the center of mass time delay and scattering angle and vice versa. The second part of our analysis of the relativistic two-body scattering problem is devoted to the dynamical properties of the scattering process. Hence, we turn to two approaches to relativistic particle mechanics: the Hamiltonian constraint models and the manifestly covariant formalism. Using general geometric arguments, we prove "gauge invariance" of the scattering transformation in the Todorov -Komar Hamiltonian constraint model. We conclude that the scattering cross sections of the Todorov-Komar models have the same angular dependence as their non-relativistic counterpart, irrespective of a choice of gauge. This limits the physical relevance of those models. We present a physically non -trivial Hamiltonian constraint model, starting from

  18. ELECTRON INJECTION BY WHISTLER WAVES IN NON-RELATIVISTIC SHOCKS

    SciTech Connect

    Riquelme, Mario A.; Spitkovsky, Anatoly E-mail: anatoly@astro.princeton.edu

    2011-05-20

    Electron acceleration to non-thermal, ultra-relativistic energies ({approx}10-100 TeV) is revealed by radio and X-ray observations of shocks in young supernova remnants (SNRs). The diffusive shock acceleration (DSA) mechanism is usually invoked to explain this acceleration, but the way in which electrons are initially energized or 'injected' into this acceleration process starting from thermal energies is an unresolved problem. In this paper we study the initial acceleration of electrons in non-relativistic shocks from first principles, using two- and three-dimensional particle-in-cell (PIC) plasma simulations. We systematically explore the space of shock parameters (the Alfvenic Mach number, M{sub A} , the shock velocity, v{sub sh}, the angle between the upstream magnetic field and the shock normal, {theta}{sub Bn}, and the ion to electron mass ratio, m{sub i} /m{sub e} ). We find that significant non-thermal acceleration occurs due to the growth of oblique whistler waves in the foot of quasi-perpendicular shocks. This acceleration strongly depends on using fairly large numerical mass ratios, m{sub i} /m{sub e} , which may explain why it had not been observed in previous PIC simulations of this problem. The obtained electron energy distributions show power-law tails with spectral indices up to {alpha} {approx} 3-4. The maximum energies of the accelerated particles are consistent with the electron Larmor radii being comparable to that of the ions, indicating potential injection into the subsequent DSA process. This injection mechanism, however, requires the shock waves to have fairly low Alfenic Mach numbers, M{sub A} {approx}< 20, which is consistent with the theoretical conditions for the growth of whistler waves in the shock foot (M{sub A} {approx}< (m{sub i} /m{sub e}){sup 1/2}). Thus, if the whistler mechanism is the only robust electron injection process at work in SNR shocks, then SNRs that display non-thermal emission must have significantly amplified

  19. Brady 1D seismic velocity model ambient noise prelim

    DOE Data Explorer

    Mellors, Robert J.

    2013-10-25

    Preliminary 1D seismic velocity model derived from ambient noise correlation. 28 Green's functions filtered between 4-10 Hz for Vp, Vs, and Qs were calculated. 1D model estimated for each path. The final model is a median of the individual models. Resolution is best for the top 1 km. Poorly constrained with increasing depth.

  20. Evaluating CoLiDeS + Pic: The Role of Relevance of Pictures in User Navigation Behaviour

    ERIC Educational Resources Information Center

    Karanam, Saraschandra; van Oostendorp, Herre; Indurkhya, Bipin

    2012-01-01

    CoLiDeS + Pic is a cognitive model of web-navigation that incorporates semantic information from pictures into CoLiDeS. In our earlier research, we have demonstrated that by incorporating semantic information from pictures, CoLiDeS + Pic can predict the hyperlinks on the shortest path more frequently, and also with greater information scent,…

  1. Evaluation of the Parent-Implemented Communication Strategies (PiCS) Project Using the Multiattribute Utility (MAU) Approach

    ERIC Educational Resources Information Center

    Stoner, Julia B.; Meadan, Hedda; Angell, Maureen E.; Daczewitz, Marcus

    2012-01-01

    We conducted a multiattribute utility (MAU) evaluation to assess the Parent-Implemented Communication Strategies (PiCS) project which was funded by the Institute of Education Sciences (IES). In the PiCS project parents of young children with developmental disabilities are trained and coached in their homes on naturalistic and visual teaching…

  2. The Serine Protease Pic From Enteroaggregative Escherichia coli Mediates Immune Evasion by the Direct Cleavage of Complement Proteins.

    PubMed

    Abreu, Afonso G; Fraga, Tatiana R; Granados Martínez, Adriana P; Kondo, Marcia Y; Juliano, Maria A; Juliano, Luiz; Navarro-Garcia, Fernando; Isaac, Lourdes; Barbosa, Angela S; Elias, Waldir P

    2015-07-01

    Enteroaggregative and uropathogenic Escherichia coli, Shigella flexneri 2a, and the hybrid enteroaggregative/Shiga toxin-producing E. coli strain (O104:H4) are important pathogens responsible for intestinal and urinary tract infections, as well as sepsis and hemolytic uremic syndrome. They have in common the production of a serine protease called Pic. Several biological roles for Pic have been described, including protection of E. coli DH5α from complement-mediated killing. Hereby we showed that Pic significantly reduces complement activation by all 3 pathways. Pic cleaves purified C3/C3b and other proteins from the classic and lectin pathways, such as C4 and C2. Cleavage fragments of C3, C4, and C2 were also observed with HB101(pPic1) culture supernatants, and C3 cleavage sites were mapped by fluorescence resonance energy transfer peptides. Experiments using human serum as a source of complement proteins confirmed Pic proteolytic activity on these proteins. Furthermore, Pic works synergistically with the human complement regulators factor I and factor H, promoting inactivation of C3b. In the presence of both regulators, further degradation of C3 α' chain was observed. Therefore, Pic may contribute to immune evasion of E. coli and S. flexneri, favoring invasiveness and increasing the severity of the disorders caused by these pathogens.

  3. Practical Relativistic Bit Commitment.

    PubMed

    Lunghi, T; Kaniewski, J; Bussières, F; Houlmann, R; Tomamichel, M; Wehner, S; Zbinden, H

    2015-07-17

    Bit commitment is a fundamental cryptographic primitive in which Alice wishes to commit a secret bit to Bob. Perfectly secure bit commitment between two mistrustful parties is impossible through an asynchronous exchange of quantum information. Perfect security is, however, possible when Alice and Bob each split into several agents exchanging classical information at times and locations suitably chosen to satisfy specific relativistic constraints. In this Letter we first revisit a previously proposed scheme [C. Crépeau et al., Lect. Notes Comput. Sci. 7073, 407 (2011)] that realizes bit commitment using only classical communication. We prove that the protocol is secure against quantum adversaries for a duration limited by the light-speed communication time between the locations of the agents. We then propose a novel multiround scheme based on finite-field arithmetic that extends the commitment time beyond this limit, and we prove its security against classical attacks. Finally, we present an implementation of these protocols using dedicated hardware and we demonstrate a 2 ms-long bit commitment over a distance of 131 km. By positioning the agents on antipodal points on the surface of Earth, the commitment time could possibly be extended to 212 ms.

  4. Phase-space moment-equation model of highly relativistic electron-beams in plasma-wakefield accelerators

    SciTech Connect

    Robson, R.E.; Mehrling, T.; Osterhoff, J.

    2015-05-15

    We formulate a new procedure for modelling the transverse dynamics of relativistic electron beams with significant energy spread when injected into plasma-based accelerators operated in the blow-out regime. Quantities of physical interest, such as the emittance, are furnished directly from solution of phase space moment equations formed from the relativistic Vlasov equation. The moment equations are closed by an Ansatz, and solved analytically for prescribed wakefields. The accuracy of the analytic formulas is established by benchmarking against the results of a semi-analytic/numerical procedure which is described within the scope of this work, and results from a simulation with the 3D quasi-static PIC code HiPACE.

  5. Endoplasmic Reticulum Glycoprotein Quality Control Regulates CD1d Assembly and CD1d-mediated Antigen Presentation*

    PubMed Central

    Kunte, Amit; Zhang, Wei; Paduraru, Crina; Veerapen, Natacha; Cox, Liam R.; Besra, Gurdyal S.; Cresswell, Peter

    2013-01-01

    The non-classical major histocompatibility complex (MHC) homologue CD1d presents lipid antigens to innate-like lymphocytes called natural-killer T (NKT) cells. These cells, by virtue of their broad cytokine repertoire, shape innate and adaptive immune responses. Here, we have assessed the role of endoplasmic reticulum glycoprotein quality control in CD1d assembly and function, specifically the role of a key component of the quality control machinery, the enzyme UDP glucose glycoprotein glucosyltransferase (UGT1). We observe that in UGT1-deficient cells, CD1d associates prematurely with β2-microglobulin (β2m) and is able to rapidly exit the endoplasmic reticulum. At least some of these CD1d-β2m heterodimers are shorter-lived and can be rescued by provision of a defined exogenous antigen, α-galactosylceramide. Importantly, we show that in UGT1-deficient cells the CD1d-β2m heterodimers have altered antigenicity despite the fact that their cell surface levels are unchanged. We propose that UGT1 serves as a quality control checkpoint during CD1d assembly and further suggest that UGT1-mediated quality control can shape the lipid repertoire of newly synthesized CD1d. The quality control process may play a role in ensuring stability of exported CD1d-β2m complexes, in facilitating presentation of low abundance high affinity antigens, or in preventing deleterious responses to self lipids. PMID:23615906

  6. EXPERIMENTAL INVESTIGATION OF PIC FORMATION DURING THE INCINERATION OF RECOVERED CFC-11

    EPA Science Inventory

    The report gives results of an investigation of the formation of products of incomplete combustion (PICS) during "recovered" trichlorofluoromethane (CFC-11) incineration. Tests involved burning the recovered CFC-11 in a propane gas flame. combustion gas samples were taken and an...

  7. Modeling Self-Ionized Plasma Wakefield Acceleration for Afterburner Parameters Using QuickPIC

    SciTech Connect

    Zhou, M.; Clayton, C.E.; Decyk, V.K.; Huang, C.; Johnson, D.K.; Joshi, C.; Lu, W.; Mori, W.B.; Tsung, F.S.; Deng, S.; Katsouleas, T.; Muggli, P.; Oz, E.; Decker, F.-J.; Iverson, R.; O'Connel, C.; Walz, D.; /SLAC

    2006-01-25

    For the parameters envisaged in possible afterburner stages[1] of a plasma wakefield accelerator (PWFA), the self-fields of the particle beam can be intense enough to tunnel ionize some neutral gases. Tunnel ionization has been investigated as a way for the beam itself to create the plasma, and the wakes generated may differ from those generated in pre-ionized plasmas[2],[3]. However, it is not practical to model the whole stage of PWFA with afterburner parameters using the models described in [2] and [3]. Here we describe the addition of a tunnel ionization package using the ADK model into QuickPIC, a highly efficient quasi-static particle in cell (PIC) code which can model a PWFA with afterburner parameters. Comparison between results from OSIRIS (a full PIC code with ionization) and from QuickPIC with the ionization package shows good agreement. Preliminary results using parameters relevant to the E164X experiment and the upcoming E167 experiment at SLAC are shown.

  8. Tissue accumulation and urinary excretion of Cr in chromium picolinate (CrPic)-supplemented lambs.

    PubMed

    Dallago, Bruno Stéfano Lima; Lima, Bárbara Alcântara Ferreira; Braz, Shélida Vasconcelos; Mustafa, Vanessa da Silva; McManus, Concepta; Paim, Tiago do Prado; Campeche, Aline; Gomes, Edgard Franco; Louvandini, Helder

    2016-05-01

    Chromium (Cr) concentrations in liver, kidney, spleen, heart, lymph node, skeletal muscle, bone, testis and urine of lambs were measured to trace the biodistribution and bioaccumulation of Cr after oral supplementation with chromium picolinate (CrPic). Twenty-four Santa Inês lambs were treated with four different concentrations of CrPic: placebo, 0.250, 0.375 and 0.500 mg of CrPic/animal/day for 84 days. The basal diet consisted of Panicum maximum cv Massai hay and concentrate. Cr concentrations were measured by ICP-MS measuring (52)Cr as collected mass. There was a positive linear relationship between dose administered and the accumulation of Cr in the heart, lungs and testis. Urinary excretion of Cr occurred in a time and dose-dependent manner, so the longer or more dietary Cr provided, the greater excretion of the element. As some non-carcass components (such as lungs or heart) are added to bone and visceral meal to feed animals, there is a risk of bioaccumulation and biomagnification due to Cr offered as CrPic in the diet.

  9. Tissue accumulation and urinary excretion of Cr in chromium picolinate (CrPic)-supplemented lambs.

    PubMed

    Dallago, Bruno Stéfano Lima; Lima, Bárbara Alcântara Ferreira; Braz, Shélida Vasconcelos; Mustafa, Vanessa da Silva; McManus, Concepta; Paim, Tiago do Prado; Campeche, Aline; Gomes, Edgard Franco; Louvandini, Helder

    2016-05-01

    Chromium (Cr) concentrations in liver, kidney, spleen, heart, lymph node, skeletal muscle, bone, testis and urine of lambs were measured to trace the biodistribution and bioaccumulation of Cr after oral supplementation with chromium picolinate (CrPic). Twenty-four Santa Inês lambs were treated with four different concentrations of CrPic: placebo, 0.250, 0.375 and 0.500 mg of CrPic/animal/day for 84 days. The basal diet consisted of Panicum maximum cv Massai hay and concentrate. Cr concentrations were measured by ICP-MS measuring (52)Cr as collected mass. There was a positive linear relationship between dose administered and the accumulation of Cr in the heart, lungs and testis. Urinary excretion of Cr occurred in a time and dose-dependent manner, so the longer or more dietary Cr provided, the greater excretion of the element. As some non-carcass components (such as lungs or heart) are added to bone and visceral meal to feed animals, there is a risk of bioaccumulation and biomagnification due to Cr offered as CrPic in the diet. PMID:27049124

  10. PIC Profiles for Learning-Disabled and Behavior-Disordered Children.

    ERIC Educational Resources Information Center

    Goh, David S.; And Others

    1984-01-01

    Compared the performance of learning-disabled and behavior-disordered children (N=60) on the Personality Inventory for Children (PIC). Results showed that learning-disabled and behavior-disordered children could be differentiated clearly on subtests that comprise the cognitive development and conduct disorder factors. However, less differentiation…

  11. A study on the apterous genus Clytomelegena Pic, 1928 (Coleoptera, Disteniidae).

    PubMed

    Lin, Meiying; Murzin, Sergey V

    2012-01-01

    The genus Noeconia Murzin, 1988 is synonymized with Clytomelegena Pic, 1928. Clytomelegena kabakovi (Murzin, 1988), comb. n. is newly recorded from China (Guangxi Prov.). And Laos (Attapeu Prov.) is a new locality of this genus. Both sexes are apterous. Photographs and genitalic descriptions of Clytomelegena kabakovi are presented for the first time.

  12. The Whole PIC Catalog: Organization, Planning and Service Delivery Options under JTPA.

    ERIC Educational Resources Information Center

    National Alliance of Business, Inc., Washington, DC.

    This handbook illustrates and discusses organizational options for the delivery of employment and training services within service delivery areas (SDAs) mandated by the Job Training Partnership Act (JTPA) of 1982. Addressed primarily to members of private industry councils (PICs), representatives of local governments, and employment and training…

  13. PIC--A Self-Paced Practical Communications Program for Technical/Vocational Students.

    ERIC Educational Resources Information Center

    Blicq, Ronald S.

    The Practical Industrial Communication (PIC) program is a form of individualized instruction that teaches communication skills to students in vocational/technical curricula at Red River Community College, Winnipeg, Manitoba. A placement test determines whether students begin with all or part of a ten-hour writing skills review or proceed directly…

  14. Synopsis of Falsocis Pic (Coleoptera, Ciidae), new species, new records and an identification key.

    PubMed

    Lopes-Andrade, Cristiano; Lawrence, John F

    2011-01-01

    Three new species of Falsocis Pic are described: Falsocis aquiloniussp. n. from Panamá, Costa Rica and Colombia, Falsocis egregiussp. n. from a single locality in northern Brazil and Falsocis occultussp. n. from two localities in southeastern and southern Brazil. New records, comparative notes and an identification key for male and female specimens of Falsocis species are also provided.

  15. The Plant Information Center (PIC): A Web-Based Learning Center for Botanical Study.

    ERIC Educational Resources Information Center

    Greenberg, J.; Daniel, E.; Massey, J.; White, P.

    The Plant Information Center (PIC) is a project funded under the Institute of Museum and Library Studies that aims to provide global access to both primary and secondary botanical resources via the World Wide Web. Central to the project is the development and employment of a series of applications that facilitate resource discovery, interactive…

  16. Simulation of Laser Wake Field Acceleration using a 2.5D PIC Code

    NASA Astrophysics Data System (ADS)

    An, W. M.; Hua, J. F.; Huang, W. H.; Tang, Ch. X.; Lin, Y. Z.

    2006-11-01

    A 2.5D PIC simulation code is developed to study the LWFA( Laser WakeField Acceleration ). The electron self-injection and the generation of mono-energetic electron beam in LWFA is briefly discussed through the simulation. And the experiment of this year at SILEX-I laser facility is also introduced.

  17. Refining a relativistic, hydrodynamic solver: Admitting ultra-relativistic flows

    NASA Astrophysics Data System (ADS)

    Bernstein, J. P.; Hughes, P. A.

    2009-09-01

    We have undertaken the simulation of hydrodynamic flows with bulk Lorentz factors in the range 102-106. We discuss the application of an existing relativistic, hydrodynamic primitive variable recovery algorithm to a study of pulsar winds, and, in particular, the refinement made to admit such ultra-relativistic flows. We show that an iterative quartic root finder breaks down for Lorentz factors above 102 and employ an analytic root finder as a solution. We find that the former, which is known to be robust for Lorentz factors up to at least 50, offers a 24% speed advantage. We demonstrate the existence of a simple diagnostic allowing for a hybrid primitives recovery algorithm that includes an automatic, real-time toggle between the iterative and analytical methods. We further determine the accuracy of the iterative and hybrid algorithms for a comprehensive selection of input parameters and demonstrate the latter’s capability to elucidate the internal structure of ultra-relativistic plasmas. In particular, we discuss simulations showing that the interaction of a light, ultra-relativistic pulsar wind with a slow, dense ambient medium can give rise to asymmetry reminiscent of the Guitar nebula leading to the formation of a relativistic backflow harboring a series of internal shockwaves. The shockwaves provide thermalized energy that is available for the continued inflation of the PWN bubble. In turn, the bubble enhances the asymmetry, thereby providing positive feedback to the backflow.

  18. Interaction of environmental contaminants with zebrafish organic anion transporting polypeptide, Oatp1d1 (Slco1d1)

    SciTech Connect

    Popovic, Marta; Zaja, Roko; Fent, Karl; Smital, Tvrtko

    2014-10-01

    Polyspecific transporters from the organic anion transporting polypeptide (OATP/Oatp) superfamily mediate the uptake of a wide range of compounds. In zebrafish, Oatp1d1 transports conjugated steroid hormones and cortisol. It is predominantly expressed in the liver, brain and testes. In this study we have characterized the transport of xenobiotics by the zebrafish Oatp1d1 transporter. We developed a novel assay for assessing Oatp1d1 interactors using the fluorescent probe Lucifer yellow and transient transfection in HEK293 cells. Our data showed that numerous environmental contaminants interact with zebrafish Oatp1d1. Oatp1d1 mediated the transport of diclofenac with very high affinity, followed by high affinity towards perfluorooctanesulfonic acid (PFOS), nonylphenol, gemfibrozil and 17α-ethinylestradiol; moderate affinity towards carbaryl, diazinon and caffeine; and low affinity towards metolachlor. Importantly, many environmental chemicals acted as strong inhibitors of Oatp1d1. A strong inhibition of Oatp1d1 transport activity was found by perfluorooctanoic acid (PFOA), chlorpyrifos-methyl, estrone (E1) and 17β-estradiol (E2), followed by moderate to low inhibition by diethyl phthalate, bisphenol A, 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4 tetrahydronapthalene and clofibrate. In this study we identified Oatp1d1 as a first Solute Carrier (SLC) transporter involved in the transport of a wide range of xenobiotics in fish. Considering that Oatps in zebrafish have not been characterized before, our work on zebrafish Oatp1d1 offers important new insights on the understanding of uptake processes of environmental contaminants, and contributes to the better characterization of zebrafish as a model species. - Highlights: • We optimized a novel assay for determination of Oatp1d1 interactors • Oatp1d1 is the first SLC characterized fish xenobiotic transporter • PFOS, nonylphenol, diclofenac, EE2, caffeine are high affinity Oatp1d1substrates • PFOA, chlorpyrifos

  19. D1/D5 dopamine receptors modulate spatial memory formation.

    PubMed

    da Silva, Weber C N; Köhler, Cristiano C; Radiske, Andressa; Cammarota, Martín

    2012-02-01

    We investigated the effect of the intra-CA1 administration of the D1/D5 receptor antagonist SCH23390 and the D1/D5 receptor agonist SKF38393 on spatial memory in the water maze. When given immediately, but not 3h after training, SCH23390 hindered long-term spatial memory formation without affecting non-spatial memory or the normal functionality of the hippocampus. On the contrary, post-training infusion of SKF38393 enhanced retention and facilitated the spontaneous recovery of the original spatial preference after reversal learning. Our findings demonstrate that hippocampal D1/D5 receptors play an essential role in spatial memory processing.

  20. Shielding of relativistic protons.

    PubMed

    Bertucci, A; Durante, M; Gialanella, G; Grossi, G; Manti, L; Pugliese, M; Scampoli, P; Mancusi, D; Sihver, L; Rusek, A

    2007-06-01

    Protons are the most abundant element in the galactic cosmic radiation, and the energy spectrum peaks around 1 GeV. Shielding of relativistic protons is therefore a key problem in the radiation protection strategy of crewmembers involved in long-term missions in deep space. Hydrogen ions were accelerated up to 1 GeV at the NASA Space Radiation Laboratory, Brookhaven National Laboratory, New York. The proton beam was also shielded with thick (about 20 g/cm2) blocks of lucite (PMMA) or aluminium (Al). We found that the dose rate was increased 40-60% by the shielding and decreased as a function of the distance along the axis. Simulations using the General-Purpose Particle and Heavy-Ion Transport code System (PHITS) show that the dose increase is mostly caused by secondary protons emitted by the target. The modified radiation field after the shield has been characterized for its biological effectiveness by measuring chromosomal aberrations in human peripheral blood lymphocytes exposed just behind the shield block, or to the direct beam, in the dose range 0.5-3 Gy. Notwithstanding the increased dose per incident proton, the fraction of aberrant cells at the same dose in the sample position was not significantly modified by the shield. The PHITS code simulations show that, albeit secondary protons are slower than incident nuclei, the LET spectrum is still contained in the low-LET range (<10 keV/microm), which explains the approximately unitary value measured for the relative biological effectiveness. PMID:17256178

  1. Relativistic breakdown in planetary atmospheres

    SciTech Connect

    Dwyer, J. R.

    2007-04-15

    In 2003, a new electrical breakdown mechanism involving the production of runaway avalanches by positive feedback from runaway positrons and energetic photons was introduced. This mechanism, which shall be referred to as 'relativistic feedback', allows runaway discharges in gases to become self-sustaining, dramatically increasing the flux of runaway electrons, the accompanying high-energy radiation, and resulting ionization. Using detailed Monte Carlo calculations, properties of relativistic feedback are investigated. It is found that once relativistic feedback fully commences, electrical breakdown will occur and the ambient electric field, extending over cubic kilometers, will be discharged in as little as 2x10{sup -5} s. Furthermore, it is found that the flux of energetic electrons and x rays generated by this mechanism can exceed the flux generated by the standard relativistic runaway electron model by a factor of 10{sup 13}, making relativistic feedback a good candidate for explaining terrestrial gamma-ray flashes and other high-energy phenomena observed in the Earth's atmosphere.

  2. Investigation of collective electron dynamics in relativistically transparent laser-foil interactions

    NASA Astrophysics Data System (ADS)

    Gray, Ross; MacLellan, David; Gonzalez-Izquierdo, Bruno; Powell, Haydn; Carroll, David; Murphy, Christopher; Stockhausen, Luca; Rusby, Dean; Scott, Graeme; Wilson, Robbie; Booth, Nicola; Symes, Dan; Hawkes, Steve; Torres, Ricardo; Borghesi, Marco; Neely, David; McKenna, Paul

    2014-10-01

    The interaction of an intense laser pulse with a solid target produces high energy electrons at the target-vacuum boundary. For sufficiently high laser intensities and thin targets, the electrons become relativistic and rapidly expand into vacuum, lowering the peak electron density. The combined increase in the relativistically-corrected critical density and the reduction in the target electron density results in the onset of relativistic induced transparency (RIT) during the laser pulse, enabling the remainder of the pulse to propagate through the target and further interact with the accelerated electrons. We report on measurements of the collective dynamics of laser driven electrons in the RIT regime. The 2D profile of the beam of accelerated electrons is shown to change from an ellipse aligned along the laser polarization direction in the case of limited RIT, to a double-lobe structure aligned perpendicular to it, for a larger degree of RIT. The temporal dynamics of the interaction are investigated via PIC simulations. The implications of RIT for laser-driven ion acceleration is also explored.

  3. Particle Acceleration, Magnetic Field Generation and Associated Emission in Collisionless Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K. I.; Ramirez-Ruiz, E.; Hardee, P.; Mizuno, Y.; Fishman. G. J.

    2007-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  4. Particle Acceleration, Magnetic Field Generation, and Associated Emission in Collisionless Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.

    2007-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron)jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  5. Development and Benchmarking of a Hybrid PIC Code For Dense Plasmas and Fast Ignition

    SciTech Connect

    Witherspoon, F. Douglas; Welch, Dale R.; Thompson, John R.; MacFarlane, Joeseph J.; Phillips, Michael W.; Bruner, Nicki; Mostrom, Chris; Thoma, Carsten; Clark, R. E.; Bogatu, Nick; Kim, Jin-Soo; Galkin, Sergei; Golovkin, Igor E.; Woodruff, P. R.; Wu, Linchun; Messer, Sarah J.

    2014-05-20

    Computational Sciences, Inc. and Advanced Energy Systems Inc. joined efforts to develop new physics and numerical models for LSP in several key areas to enhance the ability of LSP to model high energy density plasmas (HEDP). This final report details those efforts. Areas addressed in this research effort include: adding radiation transport to LSP, first in 2D and then fully 3D, extending the EMHD model to 3D, implementing more advanced radiation and electrode plasma boundary conditions, and installing more efficient implicit numerical algorithms to speed complex 2-D and 3-D computations. The new capabilities allow modeling of the dominant processes in high energy density plasmas, and further assist the development and optimization of plasma jet accelerators, with particular attention to MHD instabilities and plasma/wall interaction (based on physical models for ion drag friction and ablation/erosion of the electrodes). In the first funding cycle we implemented a solver for the radiation diffusion equation. To solve this equation in 2-D, we used finite-differencing and applied the parallelized sparse-matrix solvers in the PETSc library (Argonne National Laboratory) to the resulting system of equations. A database of the necessary coefficients for materials of interest was assembled using the PROPACEOS and ATBASE codes from Prism. The model was benchmarked against Prism's 1-D radiation hydrodynamics code HELIOS, and against experimental data obtained from HyperV's separately funded plasma jet accelerator development program. Work in the second funding cycle focused on extending the radiation diffusion model to full 3-D, continued development of the EMHD model, optimizing the direct-implicit model to speed up calculations, add in multiply ionized atoms, and improved the way boundary conditions are handled in LSP. These new LSP capabilities were then used, along with analytic calculations and Mach2 runs, to investigate plasma jet merging, plasma detachment and transport, restrike

  6. A human serotonin 1D receptor variant (5HT1D beta) encoded by an intronless gene on chromosome 6.

    PubMed Central

    Demchyshyn, L; Sunahara, R K; Miller, K; Teitler, M; Hoffman, B J; Kennedy, J L; Seeman, P; Van Tol, H H; Niznik, H B

    1992-01-01

    An intronless gene encoding a serotonin receptor (5HT1D beta) has been cloned and functionally expressed in mammalian fibroblast cultures. Based on the deduced amino acid sequence, the gene encodes a 390-amino acid protein displaying considerable homology, within putative transmembrane domains (approximately 75% identity) to the canine and human 5HT1D receptors. Membranes prepared from CHO cells stably expressing the receptor bound [3H]serotonin with high affinity (Kd 4 nM) and displayed a pharmacological profile consistent, but not identical, with that of the characterized serotonin 5HT1D receptor. Most notably, metergoline and serotonergic piperazine derivatives, as a group, display 3- to 8-fold lower affinity for the 5HT1D beta receptor than for the 5HT1D receptor, whereas both receptors display similar affinities for tryptamine derivatives, including the antimigraine drug sumatriptan. Northern blot analysis revealed an mRNA of approximately 5.5 kilobases expressed in human and monkey frontal cortex, medulla, striatum, hippocampus and amygdala but not in cerebellum, olfactory tubercle, and pituitary. The 5HT1D beta gene maps to human chromosome 6. The existence of multiple neuronal 5HT1D-like receptors may help account for some of the complexities associated with [3H]serotonin binding patterns in native membranes. Images PMID:1351684

  7. 60. BOILER CHAMBER No. 1, D LOOP STEAM GENERATOR AND ...

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

    60. BOILER CHAMBER No. 1, D LOOP STEAM GENERATOR AND MAIN COOLANT PUMP LOOKING NORTHEAST (LOCATION OOO) - Shippingport Atomic Power Station, On Ohio River, 25 miles Northwest of Pittsburgh, Shippingport, Beaver County, PA

  8. Severe Hypertriglyceridemia in Glut1D on Ketogenic Diet.

    PubMed

    Klepper, Joerg; Leiendecker, Baerbel; Heussinger, Nicole; Lausch, Ekkehart; Bosch, Friedrich

    2016-04-01

    High-fat ketogenic diets are the only treatment available for Glut1 deficiency (Glut1D). Here, we describe an 8-year-old girl with classical Glut1D responsive to a 3:1 ketogenic diet and ethosuximide. After 3 years on the diet a gradual increase of blood lipids was followed by rapid, severe asymptomatic hypertriglyceridemia (1,910 mg/dL). Serum lipid apheresis was required to determine liver, renal, and pancreatic function. A combination of medium chain triglyceride-oil and a reduction of the ketogenic diet to 1:1 ratio normalized triglyceride levels within days but triggered severe myoclonic seizures requiring comedication with sultiam. Severe hypertriglyceridemia in children with Glut1D on ketogenic diets may be underdiagnosed and harmful. In contrast to congenital hypertriglyceridemias, children with Glut1D may be treated effectively by dietary adjustments alone. PMID:26902182

  9. 1D Nanostructures: Controlled Fabrication and Energy Applications

    SciTech Connect

    Hu, Michael Z.

    2013-01-01

    Jian Wei, Xuchun Song, Chunli Yang, and Michael Z. Hu, 1D Nanostructures: Controlled Fabrication and Energy Applications, Journal of Nanomaterials, published special issue (http://www.hindawi.com/journals/jnm/si/197254/) (2013).

  10. TBC1D24 genotype–phenotype correlation

    PubMed Central

    Balestrini, Simona; Milh, Mathieu; Castiglioni, Claudia; Lüthy, Kevin; Finelli, Mattea J.; Verstreken, Patrik; Cardon, Aaron; Stražišar, Barbara Gnidovec; Holder, J. Lloyd; Lesca, Gaetan; Mancardi, Maria M.; Poulat, Anne L.; Repetto, Gabriela M.; Banka, Siddharth; Bilo, Leonilda; Birkeland, Laura E.; Bosch, Friedrich; Brockmann, Knut; Cross, J. Helen; Doummar, Diane; Félix, Temis M.; Giuliano, Fabienne; Hori, Mutsuki; Hüning, Irina; Kayserili, Hulia; Kini, Usha; Lees, Melissa M.; Meenakshi, Girish; Mewasingh, Leena; Pagnamenta, Alistair T.; Peluso, Silvio; Mey, Antje; Rice, Gregory M.; Rosenfeld, Jill A.; Taylor, Jenny C.; Troester, Matthew M.; Stanley, Christine M.; Ville, Dorothee; Walkiewicz, Magdalena; Falace, Antonio; Fassio, Anna; Lemke, Johannes R.; Biskup, Saskia; Tardif, Jessica; Ajeawung, Norbert F.; Tolun, Aslihan; Corbett, Mark; Gecz, Jozef; Afawi, Zaid; Howell, Katherine B.; Oliver, Karen L.; Berkovic, Samuel F.; Scheffer, Ingrid E.; de Falco, Fabrizio A.; Oliver, Peter L.; Striano, Pasquale; Zara, Federico

    2016-01-01

    Objective: To evaluate the phenotypic spectrum associated with mutations in TBC1D24. Methods: We acquired new clinical, EEG, and neuroimaging data of 11 previously unreported and 37 published patients. TBC1D24 mutations, identified through various sequencing methods, can be found online (http://lovd.nl/TBC1D24). Results: Forty-eight patients were included (28 men, 20 women, average age 21 years) from 30 independent families. Eighteen patients (38%) had myoclonic epilepsies. The other patients carried diagnoses of focal (25%), multifocal (2%), generalized (4%), and unclassified epilepsy (6%), and early-onset epileptic encephalopathy (25%). Most patients had drug-resistant epilepsy. We detail EEG, neuroimaging, developmental, and cognitive features, treatment responsiveness, and physical examination. In silico evaluation revealed 7 different highly conserved motifs, with the most common pathogenic mutation located in the first. Neuronal outgrowth assays showed that some TBC1D24 mutations, associated with the most severe TBC1D24-associated disorders, are not necessarily the most disruptive to this gene function. Conclusions: TBC1D24-related epilepsy syndromes show marked phenotypic pleiotropy, with multisystem involvement and severity spectrum ranging from isolated deafness (not studied here), benign myoclonic epilepsy restricted to childhood with complete seizure control and normal intellect, to early-onset epileptic encephalopathy with severe developmental delay and early death. There is no distinct correlation with mutation type or location yet, but patterns are emerging. Given the phenotypic breadth observed, TBC1D24 mutation screening is indicated in a wide variety of epilepsies. A TBC1D24 consortium was formed to develop further research on this gene and its associated phenotypes. PMID:27281533

  11. Polyanalytic relativistic second Bargmann transforms

    SciTech Connect

    Mouayn, Zouhaïr

    2015-05-15

    We construct coherent states through special superpositions of eigenstates of the relativistic isotonic oscillator. In each superposition, the coefficients are chosen to be L{sup 2}-eigenfunctions of a σ-weight Maass Laplacian on the Poincaré disk, which are associated with the eigenvalue 4m(σ−1−m), m∈Z{sub +}∩[0,(σ−1)/2]. For each nonzero m, the associated coherent states transform constitutes the m-true-polyanalytic extension of a relativistic version of the second Bargmann transform, whose integral kernel is expressed in terms of a special Appel-Kampé de Fériet’s hypergeometric function. The obtained results could be used to extend the known semi-classical analysis of quantum dynamics of the relativistic isotonic oscillator.

  12. Fluctuations in relativistic causal hydrodynamics

    NASA Astrophysics Data System (ADS)

    Kumar, Avdhesh; Bhatt, Jitesh R.; Mishra, Ananta P.

    2014-05-01

    Formalism to calculate the hydrodynamic fluctuations by applying the Onsager theory to the relativistic Navier-Stokes equation is already known. In this work, we calculate hydrodynamic fluctuations within the framework of the second order hydrodynamics of Müller, Israel and Stewart and its generalization to the third order. We have also calculated the fluctuations for several other causal hydrodynamical equations. We show that the form for the Onsager-coefficients and form of the correlation functions remain the same as those obtained by the relativistic Navier-Stokes equation and do not depend on any specific model of hydrodynamics. Further we numerically investigate evolution of the correlation function using the one dimensional boost-invariant (Bjorken) flow. We compare the correlation functions obtained using the causal hydrodynamics with the correlation function for the relativistic Navier-Stokes equation. We find that the qualitative behavior of the correlation functions remains the same for all the models of the causal hydrodynamics.

  13. Toward a relativistic gas dynamics

    SciTech Connect

    Solovev, L.S.

    1982-01-01

    Macroscopic gas dynamics on the basis of general-relativity equations is examined. An additional equation is derived which provides for completeness of the system of relativistic gasdynamic equations. Relativistic equations of two-fluid electromagnetic gas dynamics are obtained. The introduction of appropriate energy-momentum tensors makes it possible to allow for dissipative processes conditioned by viscosity, thermal conductivity, radiative thermal conductivity, ohmic resistance, and ion-electron temperature difference. The problem of generalizing the Friedmann cosmological model in the case of particle production and annihilation is considered. Also, considered are gas equilibrium in a spherically symmetric gravitational field and a two-fluid relativistic stream in an intrinsic electromagnetic field. 16 references.

  14. ELECTRON HEATING IN A RELATIVISTIC, WEIBEL-UNSTABLE PLASMA

    SciTech Connect

    Kumar, Rahul; Eichler, David; Gedalin, Michael

    2015-06-20

    The dynamics of two initially unmagnetized relativistic counter-streaming homogeneous ion–electron plasma beams are simulated in two dimensions (2D) using the particle-in-cell (PIC) method. It is shown that current filaments, which form due to the Weibel instability, develop a large-scale longitudinal electric field in the direction opposite to the current carried by the filaments as predicted by theory. This field, which is partially inductive and partially electrostatic, is identified as the main source of net electron acceleration, greatly exceeding that due to magnetic field decay at later stages. The transverse electric field, although larger than the longitudinal field, is shown to play a smaller role in heating electrons, contrary to previous claims. It is found that in one dimension, the electrons become strongly magnetized and are not accelerated beyond their initial kinetic energy. Rather, the heating of the electrons is enhanced by the bending and break up of the filaments, which releases electrons that would otherwise be trapped within a single filament and slow the development of the Weibel instability (i.e., the magnetic field growth) via induction as per Lenz’s law. In 2D simulations, electrons are heated to about one quarter of the initial kinetic energy of ions. The magnetic energy at maximum is about 4%, decaying to less than 1% by the end of the simulation. The ions are found to gradually decelerate until the end of the simulation, by which time they retain a residual anisotropy of less than 10%.

  15. Laser-driven relativistic electron beam interaction with solid dielectric

    NASA Astrophysics Data System (ADS)

    Sarkisov, G. S.; Ivanov, V. V.; Leblanc, P.; Sentoku, Y.; Yates, K.; Wiewior, P.; Chalyy, O.; Astanovitskiy, A.; Bychenkov, V. Yu.; Jobe, D.; Spielman, R. B.

    2012-07-01

    The multi-frames shadowgraphy, interferometry and polarimetry diagnostics with sub-ps time resolution were used for an investigation of ionization wave dynamics inside a glass target induced by laser-driven relativistic electron beam. Experiments were done using the 50 TW Leopard laser at the UNR. For a laser flux of ˜2×1018W/cm2 a hemispherical ionization wave propagates at c/3. The maximum of the electron density inside the glass target is ˜2×1019cm-3. Magnetic and electric fields are less than ˜15 kG and ˜1 MV/cm, respectively. The electron temperature has a maximum of ˜0.5 eV. 2D interference phase shift shows the "fountain effect" of electron beam. The very low ionization inside glass target ˜0.1% suggests a fast recombination at the sub-ps time scale. 2D PIC-simulations demonstrate radial spreading of fast electrons by self-consistent electrostatic fields.

  16. Laser-driven relativistic electron beam interaction with solid dielectric

    SciTech Connect

    Sarkisov, G. S.; Ivanov, V. V.; Leblanc, P.; Sentoku, Y.; Yates, K.; Wiewior, P.; Chalyy, O.; Astanovitskiy, A.; Bychenkov, V. Yu.; Jobe, D.; Spielman, R. B.

    2012-07-30

    The multi-frames shadowgraphy, interferometry and polarimetry diagnostics with sub-ps time resolution were used for an investigation of ionization wave dynamics inside a glass target induced by laser-driven relativistic electron beam. Experiments were done using the 50 TW Leopard laser at the UNR. For a laser flux of {approx}2 Multiplication-Sign 10{sup 18}W/cm{sup 2} a hemispherical ionization wave propagates at c/3. The maximum of the electron density inside the glass target is {approx}2 Multiplication-Sign 10{sup 19}cm{sup -3}. Magnetic and electric fields are less than {approx}15 kG and {approx}1 MV/cm, respectively. The electron temperature has a maximum of {approx}0.5 eV. 2D interference phase shift shows the 'fountain effect' of electron beam. The very low ionization inside glass target {approx}0.1% suggests a fast recombination at the sub-ps time scale. 2D PIC-simulations demonstrate radial spreading of fast electrons by self-consistent electrostatic fields.

  17. Particle-In-Cell (PIC) code simulation results and comparison with theory scaling laws for photoelectron-generated radiation

    SciTech Connect

    Dipp, T.M. |

    1993-12-01

    The generation of radiation via photoelectrons induced off of a conducting surface was explored using Particle-In-Cell (PIC) code computer simulations. Using the MAGIC PIC code, the simulations were performed in one dimension to handle the diverse scale lengths of the particles and fields in the problem. The simulations involved monoenergetic, nonrelativistic photoelectrons emitted normal to the illuminated conducting surface. A sinusoidal, 100% modulated, 6.3263 ns pulse train, as well as unmodulated emission, were used to explore the behavior of the particles, fields, and generated radiation. A special postprocessor was written to convert the PIC code simulated electron sheath into far-field radiation parameters by means of rigorous retarded time calculations. The results of the small-spot PIC simulations were used to generate various graphs showing resonance and nonresonance radiation quantities such as radiated lobe patterns, frequency, and power. A database of PIC simulation results was created and, using a nonlinear curve-fitting program, compared with theoretical scaling laws. Overall, the small-spot behavior predicted by the theoretical scaling laws was generally observed in the PIC simulation data, providing confidence in both the theoretical scaling laws and the PIC simulations.

  18. Peroxydisulfate activation by [RuII(tpy)(pic)(H2O)]+. Kinetic, mechanistic and anti-microbial activity studies.

    PubMed

    Chatterjee, Debabrata; Banerjee, Priyabrata; Bose, Jagadeesh C K; Mukhopadhyay, Sudit

    2012-03-01

    The oxidation of [Ru(II)(tpy)(pic)H(2)O](+) (tpy = 2,2',6',2''-terpyridine; pic(-) = picolinate) by peroxidisulfate (S(2)O(8)(2-)) as precursor oxidant has been investigated kinetically by UV-VIS, IR and EPR spectroscopy. The overall oxidation of Ru(II)- to Ru(IV)-species takes place in a consecutive manner involving oxidation of [Ru(II)(tpy)(pic)H(2)O](+) to [Ru(III)(tpy)(pic)(OH)](+), and its further oxidation of to the ultimate product [Ru(IV)(tpy)(pic)(O)](+) complex. The time course of the reaction was followed as a function of [S(2)O(8)(2-)], ionic strength (I) and temperature. Kinetic data and activation parameters are interpreted in terms of an outer-sphere electron transfer mechanism. Anti-microbial activity of Ru(II)(tpy)(pic)H(2)O](+) complex by inhibiting the growth of Escherichia coli DH5α in presence of peroxydisulfate has been explored, and the results of the biological studies have been discussed in terms of the [Ru(IV)(tpy)(pic)(O)](+) mediated cleavage of chromosomal DNA of the bacteria.

  19. Phenomenological Relativistic Energy Density Functionals

    SciTech Connect

    Lalazissis, G. A.; Kartzikos, S.; Niksic, T.; Paar, N.; Vretenar, D.; Ring, P.

    2009-08-26

    The framework of relativistic nuclear energy density functionals is applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of beta-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure is explored using the fully consistent quasiparticle random-phase approximation based on the relativistic Hartree-Bogoliubov model. Recent applications of energy density functionals with explicit density dependence of the meson-nucleon couplings are presented.

  20. The Pic protease of enteroaggregative Escherichia coli promotes intestinal colonization and growth in the presence of mucin.

    PubMed

    Harrington, Susan M; Sheikh, Jalaluddin; Henderson, Ian R; Ruiz-Perez, Fernando; Cohen, Paul S; Nataro, James P

    2009-06-01

    Enteroaggregative Escherichia coli (EAEC) is increasingly being recognized as a cause of diarrheal disease in diverse populations. No small animal model is currently available to study this pathogen. We report here that conventional mice orally inoculated with prototype EAEC strain 042 generally became colonized, though the abundance of organisms cultured from their stool varied substantially among individual animals. In contrast, mice whose water contained 5 g/liter streptomycin consistently became colonized at high levels (ca. 10(8) CFU/g of stool). Neither conventional nor streptomycin-treated mice developed clinical signs or histopathologic abnormalities. Using specific mutants in competition with the wild-type strain, we evaluated the contribution of several putative EAEC virulence factors to colonization of streptomycin-treated mice. Our data suggest that the dispersin surface protein and Pic, a serine protease autotransporter secreted by EAEC and Shigella flexneri, promote colonization of the mouse. In contrast, we found no role for the aggregative adherence fimbriae, the transcriptional activator AggR, or the surface factor termed Air (enteroaggregative immunoglobulin repeat protein). To study Pic further, we constructed a single nucleotide mutation in strain 042 which altered only the Pic catalytic serine (strain 042PicS258A). Fractionation of the tissue at 24 h and 3 days demonstrated an approximate 3-log(10) difference between 042 and 042PicS258A in the lumen and mucus layer and adherent to tissue. Strains 042 and 042PicS258A adhered similarly to mouse tissue ex vivo. While no growth differences were observed in a continuous-flow anaerobic intestinal simulator system, the wild-type strain exhibited a growth advantage over 042PicS258A in a culture of cecal mucus and in cecal contents in vitro; this difference was manifest only after 6 h of growth. Moreover, enhanced growth of the wild type was observed in comparison with that of the mutant in minimal

  1. Relativistic Hydrodynamics for Heavy-Ion Collisions

    ERIC Educational Resources Information Center

    Ollitrault, Jean-Yves

    2008-01-01

    Relativistic hydrodynamics is essential to our current understanding of nucleus-nucleus collisions at ultrarelativistic energies (current experiments at the Relativistic Heavy Ion Collider, forthcoming experiments at the CERN Large Hadron Collider). This is an introduction to relativistic hydrodynamics for graduate students. It includes a detailed…

  2. Relativistic treatment of inertial spin effects

    NASA Astrophysics Data System (ADS)

    Ryder, Lewis

    1998-03-01

    A relativistic spin operator for Dirac particles is identified and it is shown that a coupling of spin to angular velocity arises in the relativistic case, just as Mashhoon had speculated, and Hehl and Ni had demonstrated, in the non-relativistic case.

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

    SciTech Connect

    De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego

    2012-02-20

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  5. Electron acceleration in relativistic plasma waves generated by a single frequency short-pulse laser

    SciTech Connect

    Coverdale, C.A.; Darrow, C.B.; Decker, C.D.; Mori, W.B.; Tzeng, K.C., Clayton, C.E.; Marsh, K.A.; Joshi, C.

    1995-04-27

    Experimental evidence for the acceleration of electrons in a relativistic plasma wave generated by Raman forward scattering (SRS-F) of a single-frequency short pulse laser are presented. A 1.053 {mu}m, 600 fsec, 5 TW laser was focused into a gas jet with a peak intensity of 8{times}10{sup 17} W/cm{sup 2}. At a plasma density of 2{times}10{sup 19} cm{sup {minus}3}, 2 MeV electrons were detected and their appearance was correlated with the anti-Stokes laser sideband generated by SRS-F. The results are in good agreement with 2-D PIC simulations. The use of short pulse lasers for making ultra-high gradient accelerators is explored.

  6. Enhanced relativistic laser-plasma coupling utilizing laser-induced micromodified target

    NASA Astrophysics Data System (ADS)

    Ivanov, K. A.; Brantov, A. V.; Kudryashov, S. I.; Makarov, S. V.; Gozhev, D. A.; Volkov, R. V.; Ionin, A. A.; Bychenkov, V. Yu; Savel'ev, A. B.

    2015-04-01

    The interaction of slighly relativistic femtosecond laser radiation with microstructured Si targets was studied. The microstructuring was performed by nanosecond pulse laser ablation with additional chemical etching of the target material. An analysis was made of the optical damage under the action of femtosecond radiation near the ablation threshold. It was experimentally demonstrated that the hot electron temperature increases appreciably in the laser-driven plasma (from ~370 to almost 500 keV) as well as radiation yield in the MeV range at the interaction of a high power femtosecond laser pulse with a microstructured surface in comparison with a flat surface. Numerical simulations using 3D3V PIC code Mandor revealed that the charged particle energy growth is caused by the stochastic motion of electrons in the complex field formed by the laser field and the quasistatic field at the sharp tips of micromodifications.

  7. Radiation emission from ultra-relativistic plasma electrons in short-intense laser light interactions

    NASA Astrophysics Data System (ADS)

    Ondarza-Rovira, R.; Boyd, TJM

    2016-05-01

    Intense femtosecond laser light incident on overcritical density plasmas has shown to emit a prolific number of high-order harmonics of the driver frequency, with spectra characterised by power-law decays. When the laser pulse is p-polarised, plasma effects do modify the harmonic spectrum, weakening the so-called universal decay index p = 8/3 to 5/3. In this work appeal is made to a single particle radiation model in support of the predictions from particle-in-cell (PIC) simulations. Using these, we further show that the emission radiated by electrons -those that are relativistically accelerated inside the plasma, after being expelled into vacuum, the so-called Brunel electrons- is characterised not only by the plasma line but also by ultraviolet harmonic orders characterised by the 5/3 decay index.

  8. Modified magnetic field distribution in relativistic magnetron with diffraction output for compact operation

    SciTech Connect

    Li Wei; Liu Yonggui

    2011-02-15

    A modified magnetic field distribution in relativistic magnetron with diffraction output (MDO) for compact operation is proposed in this paper. The principle of how the modified magnetic field confines electrons drifting out of the interaction space is analyzed. The results of the particle-in-cell (PIC) simulations of the MDO with the modified magnetic field distribution show that the output power of the MDO is improved, and the long cylindrical waveguide used for collecting the drifting electrons can be omitted. The latter measure allows the horn antenna of the MDO to produce more focused energy with better directivity in the far field than it does with the long cylindrical waveguide. The MDO with the modified magnetic field distribution promises to be the real most compact narrow band high power microwave source.

  9. Ionization potential of {sup 9}Be calculated including nuclear motion and relativistic corrections

    SciTech Connect

    Stanke, Monika; Kedziera, Dariusz; Bubin, Sergiy; Adamowicz, Ludwik

    2007-05-15

    Variational calculations employing explicitly correlated Gaussian functions have been performed for the ground states of {sup 9}Be and {sup 9}Be{sup +} including the nuclear motion [i.e., without assuming the Born-Oppenheimer (BO) approximation]. An approach based on the analytical energy gradient calculated with respect to the Gaussian exponential parameters was employed, leading to energies of the two systems noticeably improved over those found in the recent paper of Pachucki and Komasa [Phys. Rev. A 73, 052502 (2006)]. The non-BO wave functions were used to calculate the {alpha}{sup 2} relativistic corrections ({alpha}=e{sup 2}/({Dirac_h}/2{pi})c). With those corrections and the {alpha}{sup 3} and {alpha}{sup 4} corrections taken from Pachucki and Komasa, a new value of the ionization potential (IP) of {sup 9}Be was determined. It agrees very well with the most recent experimental IP.

  10. Propagation of an ultra-short, intense laser in a relativistic fluid

    SciTech Connect

    Ritchie, A.B.; Decker, C.D.

    1997-12-31

    A Maxwell-relativistic fluid model is developed to describe the propagation of an ultrashort, intense laser pulse through an underdense plasma. The model makes use of numerically stabilizing fast Fourier transform (FFT) computational methods for both the Maxwell and fluid equations, and it is benchmarked against particle-in-cell (PIC) simulations. Strong fields generated in the wake of the laser are calculated, and the authors observe coherent wake-field radiation generated at harmonics of the plasma frequency due to nonlinearities in the laser-plasma interaction. For a plasma whose density is 10% of critical, the highest members of the plasma harmonic series begin to overlap with the first laser harmonic, suggesting that widely used multiple-scales-theory, by which the laser and plasma frequencies are assumed to be separable, ceases to be a useful approximation.

  11. Simulation Of Electron Cloud Effects On Electron Beam At ERL With Pipelined QuickPIC

    SciTech Connect

    Feng, B.; Muggli, P.; Huang, C.; Decyk, V.; Mori, W. B.; Hoffstaetter, G. H.; Katsouleas, T.

    2009-01-22

    With the successful implementation of pipelining algorithm to the QuickPIC code, the number of processors used is increased by 2 to 3 orders of magnitude, and the speed of the simulation is improved by a similar factor. The pipelined QuickPIC is used to simulate the electron cloud effect on electron beam in the Cornell Energy Recovery Linac (ERL) due to extremely small emittance and high peak currents anticipated in the machine. A tune shift is found due to electron cloud on electron beams, which is of equal magnitude to that on positron beams but in an opposite direction; however, emittance growth of the electron beam in an electron cloud is not observed for ERL parameters.

  12. Hybrid-PIC Algorithms for Simulation of Merging Plasma Jets in the Plasma Liner Experiment

    NASA Astrophysics Data System (ADS)

    Thoma, Carsten; Welch, Dale; Clark, Robert; Macfarlane, Joseph; Golovkin, Igor; Witherspoon, F. Douglas

    2010-11-01

    In the upcoming Plasma Liner Experiment (PLX) at Los Alamos National Laboratory a spherical array of 30-60 jets generated by plasma guns will be merged to form imploding plasma liners. We describe the Hybrid particle-in-cell (PIC) methods implemented in the code LSP for plasma jet simulation and present results of simulations of merging Ar jets. Electron macroparticles are treated as fluid elements which carry an intrinsic temperature while ion macroparticles are treated kinetically. The effective charge state is obtained from EOS tables as a function of the local plasma parameters under the assumption of local thermodynamic equilibrium (LTE). The effect of radiation cooling on the electrons is also included self-consistently into the Hybrid PIC formalism. The LSP results of jet merging simulations will be post-processed using the SPECT3D code to generate simulated radiation flux levels, spectra and images (MacFarlane et al., this meeting).

  13. Pseudo-3D PIC modeling of drift-induced spatial inhomogeneities in planar magnetron plasmas

    NASA Astrophysics Data System (ADS)

    Revel, A.; Minea, T.; Tsikata, S.

    2016-10-01

    A pseudo-3D modeling approach, based on a particle-in-cell (PIC)-Monte Carlo collisions algorithm, has been developed for the study of large- and short-scale organization of the plasma in a planar magnetron. This extension of conventional PIC modeling permits the observation of spontaneous organization of the magnetron plasma, under the influence of crossed electric and magnetic fields, into the well-known, large-scale regions of enhanced ionization and density known as spokes. The nature of complex three-dimensional electron trajectories around such structures, and non-uniform ionization within them, is revealed. This modeling provides direct numerical evidence for the existence of high-amplitude internal spoke electric fields, proposed in earlier works. A 3D phenomenological model, consistent with numerical results, is proposed. Electron density fluctuations in the megahertz range, with characteristics similar to the electron cyclotron drift instability experimentally identified in a recent Letter, are also found.

  14. Enhanced quasi-static PIC simulation with pipelining algorithm for e-cloud instability

    NASA Astrophysics Data System (ADS)

    Feng, Bing; Huang, Chengkun; Decyk, Viktor; Mori, Warren; Muggli, Patric; Katsouleas, Tom

    2008-11-01

    Simulating the electron cloud effect on a beam that circulates thousands of turns in circular machines is highly computationally demanding. A novel algorithm, the pipelining algorithm is applied to the fully parallelized quasi-static particle-in-cell code QuickPIC to overcome the limit of the maximum number of processors can be used for each time step. The pipelining algorithm divides the processors into subgroups and each subgroup focuses on different partition of the beam and performs the calculation in series. With this novel algorithm, the accuracy of the simulation is preserved; the speed of the simulation is improved by one order of magnitude with more than 10^2 processors are used. The long term simulation results of the CERN-LHC and the Main Injector at FNAL from the QuickPIC with pipelining algorithm are presented. This work is supported by SiDAC and US Department of Energy

  15. MP-Pic simulation of CFB riser with EMMS-based drag model

    SciTech Connect

    Li, F.; Song, F.; Benyahia, S.; Wang, W.; Li, J.

    2012-01-01

    MP-PIC (multi-phase particle in cell) method combined with the EMMS (energy minimization multi- scale) drag force model was implemented with the open source program MFIX to simulate the gas–solid flows in CFB (circulatingfluidizedbed) risers. Calculated solid flux by the EMMS drag agrees well with the experimental value; while the traditional homogeneous drag over-predicts this value. EMMS drag force model can also predict the macro-and meso-scale structures. Quantitative comparison of the results by the EMMS drag force model and the experimental measurements show high accuracy of the model. The effects of the number of particles per parcel and wall conditions on the simulation results have also been investigated in the paper. This work proved that MP-PIC combined with the EMMS drag model can successfully simulate the fluidized flows in CFB risers and it serves as a candidate to realize real-time simulation of industrial processes in the future.

  16. Performance and capacity analysis of Poisson photon-counting based Iter-PIC OCDMA systems.

    PubMed

    Li, Lingbin; Zhou, Xiaolin; Zhang, Rong; Zhang, Dingchen; Hanzo, Lajos

    2013-11-01

    In this paper, an iterative parallel interference cancellation (Iter-PIC) technique is developed for optical code-division multiple-access (OCDMA) systems relying on shot-noise limited Poisson photon-counting reception. The novel semi-analytical tool of extrinsic information transfer (EXIT) charts is used for analysing both the bit error rate (BER) performance as well as the channel capacity of these systems and the results are verified by Monte Carlo simulations. The proposed Iter-PIC OCDMA system is capable of achieving two orders of magnitude BER improvements and a 0.1 nats of capacity improvement over the conventional chip-level OCDMA systems at a coding rate of 1/10.

  17. Taxonomic note and description of new species of Fissocantharis Pic from China (Coleoptera, Cantharidae).

    PubMed

    Yang, Yuxia; Su, Junyan; Yang, Xingke

    2014-01-01

    Two new species of Fissocantharis Pic are described, Fissocantharisbifoveatus sp. n. (CHINA: Yunnan) and Fissocantharisacuticollis sp. n. (CHINA: Zhejiang, Fujian, Guangdong, Hunan). Fissocantharispieli (Pic, 1937) is redescribed and Fissocanthariskontumensis Wittmer, 1989 is provided with a supplementary description. Fissocantharisshanensis (Wittmer, 1997) is synonymized with Fissocanthariskontumensis. For the above four species, illustrations of male genitalia are provided, for the latter three also photos of female genitalia and abdominal sternites VIII, and for the new species photos of male habitus and antennae are presented. Additionally, the specific name of Fissocanthariswittmeri (Y. Yang et X. Yang, 2009), preoccupied by Fissocanthariswittmeri (Kazantsev, 2007), is replaced by Fissocanthariswalteri Y. Yang et X. Yang, nom. n. And Fissocanthariswittmeri (Kazantsev, 2007) is found to be a junior objective synonym of Fissocantharisdenominata (Wittmer, 1997).

  18. A revision of the genus Pseudoechthistatus Pic (Coleoptera, Cerambycidae, Lamiinae, Lamiini).

    PubMed

    Bi, Wen-Xuan; Lin, Mei-Ying

    2016-01-01

    The genus Pseudoechthistatus Pic, 1917 is redefined and revised. Five species of the genus are described as new, Pseudoechthistatus sinicus sp. n. and Pseudoechthistatus chiangshunani sp. n. from central Yunnan, China, Pseudoechthistatus pufujiae sp. n. from western Yunnan, China, and Pseudoechthistatus holzschuhi sp. n. and Pseudoechthistatus glabripennis sp. n. from southern Yunnan and northern Vietnam. Pseudoechthistatus birmanicus Breuning, 1942 is excluded from the fauna of China. Three poorly known species, Pseudoechthistatus obliquefasciatus Pic, 1917, Pseudoechthistatus granulatus Breuning, 1942, and Pseudoechthistatus acutipennis Chiang, 1981 are redescribed, and the type localities of the former two species are discussed. Endophallic structure of seven species in inflated and everted condition are studied and compared with their relatives. Illustrations of habitus and major diagnostic features of all species are provided. Some biological notes are reported. An identification key as well as a distributional map are presented.

  19. Parallelization of the GKEM Electromagnetic PIC code using MPI and OpenMP

    NASA Astrophysics Data System (ADS)

    Benjamin, Mark; Ethier, Stephane; Lee, Wei-Li

    2009-11-01

    GKEM is a legacy gyrokinetic PIC code in slab geometry that calculates anomalous transport in fusion plasmas due to drift wave microturbulence. It is currently being used to develop new algorithms for high-beta electromagnetic PIC simulations. This work focuses on the modernization and performance improvement of GKEM through the use of FORTRAN 90 language features and parallelization. MPI-based particle parallelization was implemented as well as loop-level multi-threading using OpenMP directives. Performance improvements and speedup curves for the different stages of the code are discussed. Project supported by the DOE-PPPL High School Internship Program and DOE contract DE-AC02-09CH11466.

  20. A revision of the genus Pseudoechthistatus Pic (Coleoptera, Cerambycidae, Lamiinae, Lamiini)

    PubMed Central

    Bi, Wen-Xuan; Lin, Mei-Ying

    2016-01-01

    Abstract The genus Pseudoechthistatus Pic, 1917 is redefined and revised. Five species of the genus are described as new, Pseudoechthistatus sinicus sp. n. and Pseudoechthistatus chiangshunani sp. n. from central Yunnan, China, Pseudoechthistatus pufujiae sp. n. from western Yunnan, China, and Pseudoechthistatus holzschuhi sp. n. and Pseudoechthistatus glabripennis sp. n. from southern Yunnan and northern Vietnam. Pseudoechthistatus birmanicus Breuning, 1942 is excluded from the fauna of China. Three poorly known species, Pseudoechthistatus obliquefasciatus Pic, 1917, Pseudoechthistatus granulatus Breuning, 1942, and Pseudoechthistatus acutipennis Chiang, 1981 are redescribed, and the type localities of the former two species are discussed. Endophallic structure of seven species in inflated and everted condition are studied and compared with their relatives. Illustrations of habitus and major diagnostic features of all species are provided. Some biological notes are reported. An identification key as well as a distributional map are presented. PMID:27551207

  1. Particle Acceleration in Relativistic Outflows

    NASA Technical Reports Server (NTRS)

    Bykov, Andrei; Gehrels, Neil; Krawczynski, Henric; Lemoine, Martin; Pelletier, Guy; Pohl, Martin

    2012-01-01

    In this review we confront the current theoretical understanding of particle acceleration at relativistic outflows with recent observational results on various source classes thought to involve such outflows, e.g. gamma-ray bursts, active galactic nuclei, and pulsar wind nebulae. We highlight the possible contributions of these sources to ultra-high-energy cosmic rays.

  2. Simplified Relativistic Force Transformation Equation.

    ERIC Educational Resources Information Center

    Stewart, Benjamin U.

    1979-01-01

    A simplified relativistic force transformation equation is derived and then used to obtain the equation for the electromagnetic forces on a charged particle, calculate the electromagnetic fields due to a point charge with constant velocity, transform electromagnetic fields in general, derive the Biot-Savart law, and relate it to Coulomb's law.…

  3. The serine protease motif of Pic mediates a dose-dependent mucolytic activity after binding to sugar constituents of the mucin substrate.

    PubMed

    Gutiérrez-Jiménez, Javier; Arciniega, Ivonne; Navarro-García, Fernando

    2008-08-01

    The pic gene is harbored on the chromosomes of three important pathogens: enteroaggregative Escherichia coli (EAEC), uropathogenic E. coli (UPEC), and Shigella flexneri. Since Pic is secreted into the intestinal lumen during EAEC infection, we sought to identify intestinal-mucosal substrates for Pic. Pic did not damage epithelial cells, cleave fodrin, or degrade host defense proteins embedded in the mucus layer (sIgA, lactoferrin and lysozyme). However, by using a solid-phase assay to evaluate the mucinolytic activity of EAEC Pic, we documented a specific, dose-dependent mucinolytic activity. A serine protease inhibitor and an enzymatically inactive variant of Pic were used to show that the Pic serine protease motif is required for mucinolytic activity. Pic binds mucin, and this binding was blocked in competition assays using monosaccharide constituents of the oligosaccharide side chains of mucin. Moreover, Pic mucinolytic activity decreased when sialic acid was removed from mucin. Thus, Pic is a mucinase with lectin-like activity that can be related to its reported hemagglutinin activity. Our results suggest that EAEC may secrete Pic into the intestinal lumen as a strategy for penetrating the gel-like mucus layer during EAEC colonization.

  4. A tunable relativistic backward wave oscillator based on changing concentration of the filling dielectric

    SciTech Connect

    Zhou, Hongyu; Liu, Lie; Zhao, Xuelong; Cai, Dan

    2015-04-15

    The tunable capability expands the application fields of backward wave oscillator (BWO), especially for large range modulation. This paper presents analysis, PIC simulation, and preliminary design of a novel relativistic BWO which achieves the purpose of modulation among three or more frequencies within two bands. A new dielectric slow-wave structure (SWS) with hollow section was designed in the novel BWO instead of the conventional SWS with fixed solid conductors. The wide range of adjustment of propagation constant and output frequency could be easily achieved by modulating the concentration (permittivity) of the dielectric filled in the hollow section. The results of PIC simulation show the output has three stable situations at two bands with a magnetic field of 3T: 6.9 GHz, 0.9 GW; 7.3 GHz, 1.1 GW; and 10.0 GHz, 1 GW. The specific permittivities of the corresponding SWSs are 15.7, 34.3, and 42.0, respectively.

  5. Influence of wall plasma on microwave frequency and power in relativistic backward wave oscillator

    SciTech Connect

    Sun, Jun; Cao, Yibing; Teng, Yan; Zhang, Yuchuan; Chen, Changhua; Wu, Ping

    2015-07-15

    The RF breakdown of the slow wave structure (SWS), which will lead to the generation of the wall plasma, is an important cause for pulse shortening in relativistic backward wave oscillators. Although many researchers have performed profitable studies about this issue, the influence mechanism of this factor on the microwave generation still remains not-so-clear. This paper simplifies the wall plasma with an “effective” permittivity and researches its influence on the microwave frequency and power. The dispersion relation of the SWS demonstrates that the introduction of the wall plasma will move the dispersion curves upward to some extent, which is confirmed by particle-in-cell (PIC) simulations and experiments. The plasma density and volume mainly affect the dispersion relation at the upper and lower frequency limits of each mode, respectively. Meanwhile, PIC simulations show that even though no direct power absorption exists since the wall plasma is assumed to be static, the introduction of the wall plasma may also lead to the decrease in microwave power by changing the electrodynamic property of the SWS.

  6. Operational Test Report (OTR) for U-102 Pumping and Instrumentation and Control (PIC) Skid

    SciTech Connect

    KOCH, M.R.

    2000-02-28

    Attached is the completed Operation Test Procedure (OTP-200-004, Rev. A-19 and Rev. A-20). OTP includes a print out of the Programmable Logic Controller (PLC) Ladder Diagram. Ladder Diagram was designed for installation in the PLC used to monitor and control pumping activity for Tank Farm 241-U-102. The completed OTP and OTR are referenced in the IS PIC Skid Configuration Drawing (H-2-829998).

  7. PIC codes for plasma accelerators on emerging computer architectures (GPUS, Multicore/Manycore CPUS)

    NASA Astrophysics Data System (ADS)

    Vincenti, Henri

    2016-03-01

    The advent of exascale computers will enable 3D simulations of a new laser-plasma interaction regimes that were previously out of reach of current Petasale computers. However, the paradigm used to write current PIC codes will have to change in order to fully exploit the potentialities of these new computing architectures. Indeed, achieving Exascale computing facilities in the next decade will be a great challenge in terms of energy consumption and will imply hardware developments directly impacting our way of implementing PIC codes. As data movement (from die to network) is by far the most energy consuming part of an algorithm future computers will tend to increase memory locality at the hardware level and reduce energy consumption related to data movement by using more and more cores on each compute nodes (''fat nodes'') that will have a reduced clock speed to allow for efficient cooling. To compensate for frequency decrease, CPU machine vendors are making use of long SIMD instruction registers that are able to process multiple data with one arithmetic operator in one clock cycle. SIMD register length is expected to double every four years. GPU's also have a reduced clock speed per core and can process Multiple Instructions on Multiple Datas (MIMD). At the software level Particle-In-Cell (PIC) codes will thus have to achieve both good memory locality and vectorization (for Multicore/Manycore CPU) to fully take advantage of these upcoming architectures. In this talk, we present the portable solutions we implemented in our high performance skeleton PIC code PICSAR to both achieve good memory locality and cache reuse as well as good vectorization on SIMD architectures. We also present the portable solutions used to parallelize the Pseudo-sepctral quasi-cylindrical code FBPIC on GPUs using the Numba python compiler.

  8. Taxonomic notes relating to Glenea diversenotata Schwarzer and G. quadriguttata Pic (Coleoptera, Cerambycidae, Lamiinae).

    PubMed

    Lin, Mei-Ying; Lingafelter, Steven W

    2016-01-01

    Glenea diversenotata Schwarzer, 1925 is reinstated from a subspecies of Glenea tonkinea Aurivillius, 1925 to species level and Glenea neohumerosa Lin & Yang, 2011 is a new junior synonym. Some biological information on Glenea diversenotata is recorded for the first time, including pictures of the larva and pupa. Glenea quadriguttata Pic, 1926 is reinstated from a subspecies of Glenea lacteomaculata Schwarzer, 1925 to species level. Lectotypes for Glenea lacteomaculata and Glenea quadriguttata are designated. A modified key to the related species is presented.

  9. Operational Test Report (OTR) for U-103 Pumping and Instrumentation and Control (PIC) Skid

    SciTech Connect

    KOCH, M.R.

    2000-02-28

    Attached is the completed Operation Test Procedure (OTP-200-004, Rev. A-16). OTP includes a print out of the Programmable Logic Controller (PLC) Ladder Diagram. Ladder Diagram was designed for installation in the PLC used to monitor and control pumping activity for Tank Farm 241-U-103. The completed OTP and OTR are referenced in the 25 PIC Skid Configuration Drawing (H-2-829998).

  10. Operational Test Report (OTR) for U-105 Pumping and Instrumentation and Control (PIC) Skid

    SciTech Connect

    KOCH, M.R.

    2000-02-28

    Attached is the completed Operation Test Procedure (OTP-200-004, Rev. A-18). OTP includes a print out of the Programmable Logic Controller (PLC) Ladder Diagram. Ladder Diagram was designed for installation in the PLC used to monitor and control pumping activity for Tank Farm 241-U-105. The completed OTP and OTR are referenced in the IS PIC Skid Configuration Drawing (H-2-829998).

  11. Fast lattice Boltzmann solver for relativistic hydrodynamics.

    PubMed

    Mendoza, M; Boghosian, B M; Herrmann, H J; Succi, S

    2010-07-01

    A lattice Boltzmann formulation for relativistic fluids is presented and numerically validated through quantitative comparison with recent hydrodynamic simulations of relativistic fluids. In order to illustrate its capability to handle complex geometries, the scheme is also applied to the case of a three-dimensional relativistic shock wave, generated by a supernova explosion, impacting on a massive interstellar cloud. This formulation opens up the possibility of exporting the proven advantages of lattice Boltzmann methods, namely, computational efficiency and easy handling of complex geometries, to the context of (mildly) relativistic fluid dynamics at large, from quark-gluon plasmas up to supernovae with relativistic outflows.

  12. Fast lattice Boltzmann solver for relativistic hydrodynamics.

    PubMed

    Mendoza, M; Boghosian, B M; Herrmann, H J; Succi, S

    2010-07-01

    A lattice Boltzmann formulation for relativistic fluids is presented and numerically validated through quantitative comparison with recent hydrodynamic simulations of relativistic fluids. In order to illustrate its capability to handle complex geometries, the scheme is also applied to the case of a three-dimensional relativistic shock wave, generated by a supernova explosion, impacting on a massive interstellar cloud. This formulation opens up the possibility of exporting the proven advantages of lattice Boltzmann methods, namely, computational efficiency and easy handling of complex geometries, to the context of (mildly) relativistic fluid dynamics at large, from quark-gluon plasmas up to supernovae with relativistic outflows. PMID:20867451

  13. Relativistic formulation of the Voigt profile

    NASA Astrophysics Data System (ADS)

    Wcisło, P.; Amodio, P.; Ciuryło, R.; Gianfrani, L.

    2015-02-01

    The relativistic formulation of the Voigt profile is reported for the spontaneous emission from an atomic or molecular cloud, in coincidence with a given spectral line. We considered the simultaneous occurrence of homogeneous broadening and thermal broadening, this latter being determined by the relativistic Doppler effect. Our formula for the relativistic Voigt profile reproduces those characterizing the two available limit cases, namely, the relativistic Gaussian profile and the classical Voigt convolution. The relativistic deformation of the Voigt profile was carefully quantified at different temperatures, in the case of the molecular hydrogen spectrum.

  14. Simulations of Relativistic Extragalactic Jets

    NASA Astrophysics Data System (ADS)

    Hughes, P. A.; Duncan, G. C.

    1994-05-01

    We present results for 2-D, axisymmetric simulations of flows with Lorentz factors ~ 5 -- 10, typical of values inferred for superluminal BL Lacs and QSOs. The simulations were performed with a numerical hydrodynamic code that admits relativistic flow speed. We exploit the property that the relativistic Euler equations for mass, momentum and total energy densities in the laboratory frame have the same form as the nonrelativistic equations, to solve for laboratory frame variables using a conventional Godunov-type scheme with approximate Riemann solver: the HLLE method. The relativistic nature of the flow is incorporated by performing a Lorentz transformation at every step, at each cell center or cell boundary where pressure, sound speed or velocity are required. Determination of the velocity in this manner is a robust algebraic procedure within which we can ensure that vrelativistic flows exhibit a less pronounced pattern of incident and reflection shocks on axis. For flows which have propagated to a fixed number of jet radii, the Kelvin-Helmholtz instability at the contact surface is much less evident in the high Lorentz factor cases, supporting the contention that relativistic flows are less prone to such instability. We describe how the morphology of the cocoon and shocked ambient gas change with increasing Lorentz factor. This work was supported by NSF grant AST 9120224 and by the Ohio Supercomputer Center from a Cray Research Software Development Grant.

  15. 1D nanocrystals with precisely controlled dimensions, compositions, and architectures

    NASA Astrophysics Data System (ADS)

    Pang, Xinchang; He, Yanjie; Jung, Jaehan; Lin, Zhiqun

    2016-09-01

    The ability to synthesize a diverse spectrum of one-dimensional (1D) nanocrystals presents an enticing prospect for exploring nanoscale size- and shape-dependent properties. Here we report a general strategy to craft a variety of plain nanorods, core-shell nanorods, and nanotubes with precisely controlled dimensions and compositions by capitalizing on functional bottlebrush-like block copolymers with well-defined structures and narrow molecular weight distributions as nanoreactors. These cylindrical unimolecular nanoreactors enable a high degree of control over the size, shape, architecture, surface chemistry, and properties of 1D nanocrystals. We demonstrate the synthesis of metallic, ferroelectric, upconversion, semiconducting, and thermoelectric 1D nanocrystals, among others, as well as combinations thereof.

  16. The GIRAFFE Archive: 1D and 3D Spectra

    NASA Astrophysics Data System (ADS)

    Royer, F.; Jégouzo, I.; Tajahmady, F.; Normand, J.; Chilingarian, I.

    2013-10-01

    The GIRAFFE Archive (http://giraffe-archive.obspm.fr) contains the reduced spectra observed with the intermediate and high resolution multi-fiber spectrograph installed at VLT/UT2 (ESO). In its multi-object configuration and the different integral field unit configurations, GIRAFFE produces 1D spectra and 3D spectra. We present here the status of the archive and the different functionalities to select and download both 1D and 3D data products, as well as the present content. The two collections are available in the VO: the 1D spectra (summed in the case of integral field observations) and the 3D field observations. These latter products can be explored using the VO Paris Euro3D Client (http://voplus.obspm.fr/ chil/Euro3D).

  17. PC-1D installation manual and user's guide

    SciTech Connect

    Basore, P.A.

    1991-05-01

    PC-1D is a software package for personal computers that uses finite-element analysis to solve the fully-coupled two-carrier semiconductor transport equations in one dimension. This program is particularly useful for analyzing the performance of optoelectronic devices such as solar cells, but can be applied to any bipolar device whose carrier flows are primarily one-dimensional. This User's Guide provides the information necessary to install PC-1D, define a problem for solution, solve the problem, and examine the results. Example problems are presented which illustrate these steps. The physical models and numerical methods utilized are presented in detail. This document supports version 3.1 of PC-1D, which incorporates faster numerical algorithms with better convergence properties than previous versions of the program. 51 refs., 17 figs., 5 tabs.

  18. Pitch-based pattern splitting for 1D layout

    NASA Astrophysics Data System (ADS)

    Nakayama, Ryo; Ishii, Hiroyuki; Mikami, Koji; Tsujita, Koichiro; Yaegashi, Hidetami; Oyama, Kenichi; Smayling, Michael C.; Axelrad, Valery

    2015-07-01

    The pattern splitting algorithm for 1D Gridded-Design-Rules layout (1D layout) for sub-10 nm node logic devices is shown. It is performed with integer linear programming (ILP) based on the conflict graph created from a grid map for each designated pitch. The relation between the number of times for patterning and the minimum pitch is shown systematically with a sample pattern of contact layer for each node. From the result, the number of times for patterning for 1D layout is fewer than that for conventional 2D layout. Moreover, an experimental result including SMO and total integrated process with hole repair technique is presented with the sample pattern of contact layer whose pattern density is relatively high among critical layers (fin, gate, local interconnect, contact, and metal).

  19. 1D nanocrystals with precisely controlled dimensions, compositions, and architectures.

    PubMed

    Pang, Xinchang; He, Yanjie; Jung, Jaehan; Lin, Zhiqun

    2016-09-16

    The ability to synthesize a diverse spectrum of one-dimensional (1D) nanocrystals presents an enticing prospect for exploring nanoscale size- and shape-dependent properties. Here we report a general strategy to craft a variety of plain nanorods, core-shell nanorods, and nanotubes with precisely controlled dimensions and compositions by capitalizing on functional bottlebrush-like block copolymers with well-defined structures and narrow molecular weight distributions as nanoreactors. These cylindrical unimolecular nanoreactors enable a high degree of control over the size, shape, architecture, surface chemistry, and properties of 1D nanocrystals. We demonstrate the synthesis of metallic, ferroelectric, upconversion, semiconducting, and thermoelectric 1D nanocrystals, among others, as well as combinations thereof. PMID:27634531

  20. Flexible Photodetectors Based on 1D Inorganic Nanostructures

    PubMed Central

    Lou, Zheng

    2015-01-01

    Flexible photodetectors with excellent flexibility, high mechanical stability and good detectivity, have attracted great research interest in recent years. 1D inorganic nanostructures provide a number of opportunities and capabilities for use in flexible photodetectors as they have unique geometry, good transparency, outstanding mechanical flexibility, and excellent electronic/optoelectronic properties. This article offers a comprehensive review of several types of flexible photodetectors based on 1D nanostructures from the past ten years, including flexible ultraviolet, visible, and infrared photodetectors. High‐performance organic‐inorganic hybrid photodetectors, as well as devices with 1D nanowire (NW) arrays, are also reviewed. Finally, new concepts of flexible photodetectors including piezophototronic, stretchable and self‐powered photodetectors are examined to showcase the future research in this exciting field. PMID:27774404

  1. Design and implementation of the standards-based personal intelligent self-management system (PICS).

    PubMed

    von Bargen, Tobias; Gietzelt, Matthias; Britten, Matthias; Song, Bianying; Wolf, Klaus-Hendrik; Kohlmann, Martin; Marschollek, Michael; Haux, Reinhold

    2013-01-01

    Against the background of demographic change and a diminishing care workforce there is a growing need for personalized decision support. The aim of this paper is to describe the design and implementation of the standards-based personal intelligent care systems (PICS). PICS makes consistent use of internationally accepted standards such as the Health Level 7 (HL7) Arden syntax for the representation of the decision logic, HL7 Clinical Document Architecture for information representation and is based on a open-source service-oriented architecture framework and a business process management system. Its functionality is exemplified for the application scenario of a patient suffering from congestive heart failure. Several vital signs sensors provide data for the decision support system, and a number of flexible communication channels are available for interaction with patient or caregiver. PICS is a standards-based, open and flexible system enabling personalized decision support. Further development will include the implementation of components on small computers and sensor nodes.

  2. Design and implementation of the standards-based personal intelligent self-management system (PICS).

    PubMed

    von Bargen, Tobias; Gietzelt, Matthias; Britten, Matthias; Song, Bianying; Wolf, Klaus-Hendrik; Kohlmann, Martin; Marschollek, Michael; Haux, Reinhold

    2013-01-01

    Against the background of demographic change and a diminishing care workforce there is a growing need for personalized decision support. The aim of this paper is to describe the design and implementation of the standards-based personal intelligent care systems (PICS). PICS makes consistent use of internationally accepted standards such as the Health Level 7 (HL7) Arden syntax for the representation of the decision logic, HL7 Clinical Document Architecture for information representation and is based on a open-source service-oriented architecture framework and a business process management system. Its functionality is exemplified for the application scenario of a patient suffering from congestive heart failure. Several vital signs sensors provide data for the decision support system, and a number of flexible communication channels are available for interaction with patient or caregiver. PICS is a standards-based, open and flexible system enabling personalized decision support. Further development will include the implementation of components on small computers and sensor nodes. PMID:23542984

  3. Structure of promoter-bound TFIID and insight into human PIC assembly

    PubMed Central

    Louder, Robert K.; He, Yuan; López-Blanco, José Ramón; Fang, Jie; Chacón, Pablo; Nogales, Eva

    2016-01-01

    The general transcription factor IID (TFIID) plays a central role in the initiation of RNA polymerase II-dependent transcription by nucleating pre-initiation complex (PIC) assembly at the core promoter. TFIID comprises the TATA-binding protein (TBP) and 13 TBP-associated factors (TAF1-13), which specifically interact with a variety of core promoter DNA sequences. Here we present the structure of human TFIID in complex with TFIIA and core promoter DNA, determined by single-particle cryo-electron microscopy (cryo-EM) at sub-nanometer resolution. All core promoter elements are contacted by subunits of TFIID, with TAF1 and TAF2 mediating major interactions with the downstream promoter. TFIIA bridges the TBP-TATA complex with lobe B of TFIID. We also present the cryo-EM reconstruction of a fully-assembled human TAF-less PIC. Superposition of common elements between the two structures provides novel insights into the general role of TFIID in promoter recognition, PIC assembly, and transcription initiation. PMID:27007846

  4. Probing the innermost regions of the beta Pic planetary system with near-infrared interferometry

    NASA Astrophysics Data System (ADS)

    Absil, O.; Defrére, D.; Le Bouquin, J.-B.; Augereau, J.-C., Lebreton, J.; Lagrange, A.-M.

    2014-09-01

    In this talk, I will review the near-infrared interferometric view of the innermost regions (< 4 AU) around beta Pictoris. I will first present the results of VLTI/AMBER and VLTI/PIONIER observations aiming to detect faint companions around beta Pic. These data sets allow us to exclude the presence of companions a few hundred times as faint as the central star at angular separations up to about 100 mas. The median sensitivity in our search region corresponds to a brown dwarf of about 30 Mjup at beta Pic's age. I will then discuss the search for hot circumstellar dust that we carried out with VLTI/PIONIER. Based on accurate squared visibilities obtained at short baselines, we have been able to identify the presence of resolved circumstellar emission with an integrated brightness amounting to about 1.4% of the stellar brightness in H band. The spectral shape of the detected excess across the H band is consistant with thermal emission and/or reflected light from hot dust grains located in the innermost regions of the planetary system, although forward scattering by dust grains located further away (but still within the PIONIER field-of-view, i.e., close to the line of sight) could also significantly contribute to the detected circumstellar emission. I will conclude with a brief discussion of the implications of these interferometric observations on our view of the planetary system architecture around beta Pic.

  5. 3D-PIC simulation of an inductively coupled ion source

    NASA Astrophysics Data System (ADS)

    Henrich, Robert; Muehlich, Nina Sarah; Becker, Michael; Heiliger, Christian

    2015-09-01

    Inductively coupled ion sources are applied to a wide range of plasma applications, especially surface modifications. The knowledge of the behavior and precise information of the plasma parameters are of main importance. These values are tedious to measure without influencing the discharge. By applying our fully three-dimensional PlasmaPIC tool we are able to reach these plasma parameters with a spatial and temporal resolution which is quite hard to achieve experimentally. PlasmaPIC is used for modeling discharges in arbitrary geometries without limitations to any symmetry. By this means we are able to demonstrate that the plasma density has an irrotational character. Furthermore, we will show the dependence of the plasma parameters of different working conditions. We will show that for gridded inductively coupled ion sources the neutral gas pressure inside the discharge chamber depends on the extraction of ions. This effect is considered in PlasmaPIC by a self-consistent coupling of the neutral gas simulation and the plasma simulation whereas the neutral gas distribution is calculated using the direct simulation Monte Carlo method (DSMC). This work has been supported by the ``Bundesministerium fuer Wirtschaft und Energie.'' Grant 50RS1507.

  6. Spacecraft charging analysis with the implicit particle-in-cell code iPic3D

    SciTech Connect

    Deca, J.; Lapenta, G.; Marchand, R.; Markidis, S.

    2013-10-15

    We present the first results on the analysis of spacecraft charging with the implicit particle-in-cell code iPic3D, designed for running on massively parallel supercomputers. The numerical algorithm is presented, highlighting the implementation of the electrostatic solver and the immersed boundary algorithm; the latter which creates the possibility to handle complex spacecraft geometries. As a first step in the verification process, a comparison is made between the floating potential obtained with iPic3D and with Orbital Motion Limited theory for a spherical particle in a uniform stationary plasma. Second, the numerical model is verified for a CubeSat benchmark by comparing simulation results with those of PTetra for space environment conditions with increasing levels of complexity. In particular, we consider spacecraft charging from plasma particle collection, photoelectron and secondary electron emission. The influence of a background magnetic field on the floating potential profile near the spacecraft is also considered. Although the numerical approaches in iPic3D and PTetra are rather different, good agreement is found between the two models, raising the level of confidence in both codes to predict and evaluate the complex plasma environment around spacecraft.

  7. History of planetary science. The Pic du Midi Planetary Observation Project : 1941-1971

    NASA Astrophysics Data System (ADS)

    Dollfus, Audouin

    1998-08-01

    When, in 1941, Bernard Lyot attempted to observe planet Mars at Pic du Midi, he experienced unusual viewing conditions. He realized that this circumstance was not at all exceptional for the Pic but representative of a remarkable property of the high altitude site. He decided to design, and put into operation at the top of the mountain a refractor, 60 cm in diameter, specially conceived for high angular resolution. With such a capability, Henry Camichel, Jean Focas and Audouin Dollfus initiated a deep and long-term research project based upon planetary surface exploration, with high telescopic magnification. Visual analysis, photographic work, double image micrometry, photometric and polarimetric sensing were the most frequently used techniques and they were combined. Full exploitation of all these approaches required 30 years of continuous work, essentially coordinated by Observatoire de Paris at Meudon. The project was completed almost at the time when spacecraft missions within the Solar System began to replace telescopic work for planetary physics. At this time, the Pic du Midi work have released new basic physical properties about planets and satellites. Knowledge was acquired and fundamental problems settled, which are reviewed.

  8. Three-dimensional relativistic pair plasma reconnection with radiative feedback in the Crab Nebula

    SciTech Connect

    Cerutti, B.; Werner, G. R.; Uzdensky, D. A.; Begelman, M. C. E-mail: greg.werner@colorado.edu E-mail: mitch@jila.colorado.edu

    2014-02-20

    The discovery of rapid synchrotron gamma-ray flares above 100 MeV from the Crab Nebula has attracted new interest in alternative particle acceleration mechanisms in pulsar wind nebulae. Diffuse shock-acceleration fails to explain the flares because particle acceleration and emission occur during a single or even sub-Larmor timescale. In this regime, the synchrotron energy losses induce a drag force on the particle motion that balances the electric acceleration and prevents the emission of synchrotron radiation above 160 MeV. Previous analytical studies and two-dimensional (2D) particle-in-cell (PIC) simulations indicate that relativistic reconnection is a viable mechanism to circumvent the above difficulties. The reconnection electric field localized at X-points linearly accelerates particles with little radiative energy losses. In this paper, we check whether this mechanism survives in three dimension (3D), using a set of large PIC simulations with radiation reaction force and with a guide field. In agreement with earlier works, we find that the relativistic drift kink instability deforms and then disrupts the layer, resulting in significant plasma heating but few non-thermal particles. A moderate guide field stabilizes the layer and enables particle acceleration. We report that 3D magnetic reconnection can accelerate particles above the standard radiation reaction limit, although the effect is less pronounced than in 2D with no guide field. We confirm that the highest-energy particles form compact bunches within magnetic flux ropes, and a beam tightly confined within the reconnection layer, which could result in the observed Crab flares when, by chance, the beam crosses our line of sight.

  9. Three-dimensional Relativistic Pair Plasma Reconnection with Radiative Feedback in the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Cerutti, B.; Werner, G. R.; Uzdensky, D. A.; Begelman, M. C.

    2014-02-01

    The discovery of rapid synchrotron gamma-ray flares above 100 MeV from the Crab Nebula has attracted new interest in alternative particle acceleration mechanisms in pulsar wind nebulae. Diffuse shock-acceleration fails to explain the flares because particle acceleration and emission occur during a single or even sub-Larmor timescale. In this regime, the synchrotron energy losses induce a drag force on the particle motion that balances the electric acceleration and prevents the emission of synchrotron radiation above 160 MeV. Previous analytical studies and two-dimensional (2D) particle-in-cell (PIC) simulations indicate that relativistic reconnection is a viable mechanism to circumvent the above difficulties. The reconnection electric field localized at X-points linearly accelerates particles with little radiative energy losses. In this paper, we check whether this mechanism survives in three dimension (3D), using a set of large PIC simulations with radiation reaction force and with a guide field. In agreement with earlier works, we find that the relativistic drift kink instability deforms and then disrupts the layer, resulting in significant plasma heating but few non-thermal particles. A moderate guide field stabilizes the layer and enables particle acceleration. We report that 3D magnetic reconnection can accelerate particles above the standard radiation reaction limit, although the effect is less pronounced than in 2D with no guide field. We confirm that the highest-energy particles form compact bunches within magnetic flux ropes, and a beam tightly confined within the reconnection layer, which could result in the observed Crab flares when, by chance, the beam crosses our line of sight.

  10. Relativistic ionization fronts in gas jets

    NASA Astrophysics Data System (ADS)

    Lemos, Nuno; Dias, J. M.; Gallacher, J. G.; Issac, R. C.; Fonseca, R. A.; Lopes, N. C.; Silva, L. O.; Mendonça, J. T.; Jaroszynski, D. A.

    2006-10-01

    A high-power ultra-short laser pulse propagating through a gas jet, ionizes the gas by tunnelling ionization, creating a relativistic plasma-gas interface. The relativistic ionization front that is created can be used to frequency up-shift electromagnetic radiation either in co-propagation or in counter-propagation configurations. In the counter-propagation configuration, ionization fronts can act as relativistic mirrors for terahertz radiation, leading to relativistic double Doppler frequency up-shift to the visible range. In this work, we identified and explored, the parameters that optimize the key features of relativistic ionization fronts for terahertz radiation reflection. The relativistic ionization front generated by a high power laser (TOPS) propagating in a supersonic gas jet generated by a Laval nozzle has been fully characterized. We have also performed detailed two-dimensional relativistic particle-in-cell simulations with Osiris 2.0 to analyze the generation and propagation of the ionization fronts.

  11. GIS-BASED 1-D DIFFUSIVE WAVE OVERLAND FLOW MODEL

    SciTech Connect

    KALYANAPU, ALFRED; MCPHERSON, TIMOTHY N.; BURIAN, STEVEN J.

    2007-01-17

    This paper presents a GIS-based 1-d distributed overland flow model and summarizes an application to simulate a flood event. The model estimates infiltration using the Green-Ampt approach and routes excess rainfall using the 1-d diffusive wave approximation. The model was designed to use readily available topographic, soils, and land use/land cover data and rainfall predictions from a meteorological model. An assessment of model performance was performed for a small catchment and a large watershed, both in urban environments. Simulated runoff hydrographs were compared to observations for a selected set of validation events. Results confirmed the model provides reasonable predictions in a short period of time.

  12. Observation of Dynamical Fermionization in 1D Bose Gases

    NASA Astrophysics Data System (ADS)

    Malvania, Neel; Xia, Lin; Xu, Wei; Wilson, Joshua M.; Zundel, Laura A.; Rigol, Marcos; Weiss, David S.

    2016-05-01

    The momentum distribution of a harmonically trapped 1D Bose gases in the Tonks-Girardeau limit is expected to undergo dynamical fermionization. That is, after the harmonic trap is suddenly turned off, the momentum distribution steadily transforms into that of an ideal Fermi gas in the same initial trap. We measure 1D momentum distributions at variable times after such a quench, and observe the predicted dynamical fermionization. In addition to working in the strong coupling limit, we also perform the experiment with intermediate coupling, where theoretical calculations are more challenging.

  13. Review of multi-dimensional large-scale kinetic simulation and physics validation of ion acceleration in relativistic laser-matter interaction

    SciTech Connect

    Wu, Hui-Chun; Hegelich, B.M.; Fernandez, J.C.; Shah, R.C.; Palaniyappan, S.; Jung, D.; Yin, L; Albright, B.J.; Bowers, K.; Huang, C.; Kwan, T.J.

    2012-06-19

    Two new experimental technologies enabled realization of Break-out afterburner (BOA) - High quality Trident laser and free-standing C nm-targets. VPIC is an powerful tool for fundamental research of relativistic laser-matter interaction. Predictions from VPIC are validated - Novel BOA and Solitary ion acceleration mechanisms. VPIC is a fully explicit Particle In Cell (PIC) code: models plasma as billions of macro-particles moving on a computational mesh. VPIC particle advance (which typically dominates computation) has been optimized extensively for many different supercomputers. Laser-driven ions lead to realization promising applications - Ion-based fast ignition; active interrogation, hadron therapy.

  14. Non-cooperative Brownian donkeys: A solvable 1D model

    NASA Astrophysics Data System (ADS)

    Jiménez de Cisneros, B.; Reimann, P.; Parrondo, J. M. R.

    2003-12-01

    A paradigmatic 1D model for Brownian motion in a spatially symmetric, periodic system is tackled analytically. Upon application of an external static force F the system's response is an average current which is positive for F < 0 and negative for F > 0 (absolute negative mobility). Under suitable conditions, the system approaches 100% efficiency when working against the external force F.

  15. 1D design style implications for mask making and CEBL

    NASA Astrophysics Data System (ADS)

    Smayling, Michael C.

    2013-09-01

    At advanced nodes, CMOS logic is being designed in a highly regular design style because of the resolution limitations of optical lithography equipment. Logic and memory layouts using 1D Gridded Design Rules (GDR) have been demonstrated to nodes beyond 12nm.[1-4] Smaller nodes will require the same regular layout style but with multiple patterning for critical layers. One of the significant advantages of 1D GDR is the ease of splitting layouts into lines and cuts. A lines and cuts approach has been used to achieve good pattern fidelity and process margin to below 12nm.[4] Line scaling with excellent line-edge roughness (LER) has been demonstrated with self-aligned spacer processing.[5] This change in design style has important implications for mask making: • The complexity of the masks will be greatly reduced from what would be required for 2D designs with very complex OPC or inverse lithography corrections. • The number of masks will initially increase, as for conventional multiple patterning. But in the case of 1D design, there are future options for mask count reduction. • The line masks will remain simple, with little or no OPC, at pitches (1x) above 80nm. This provides an excellent opportunity for continual improvement of line CD and LER. The line pattern will be processed through a self-aligned pitch division sequence to divide pitch by 2 or by 4. • The cut masks can be done with "simple OPC" as demonstrated to beyond 12nm.[6] Multiple simple cut masks may be required at advanced nodes. "Coloring" has been demonstrated to below 12nm for two colors and to 8nm for three colors. • Cut/hole masks will eventually be replaced by e-beam direct write using complementary e-beam lithography (CEBL).[7-11] This transition is gated by the availability of multiple column e-beam systems with throughput adequate for high- volume manufacturing. A brief description of 1D and 2D design styles will be presented, followed by examples of 1D layouts. Mask complexity for 1

  16. Relativistic rocket: Dream and reality

    NASA Astrophysics Data System (ADS)

    Semyonov, Oleg G.

    2014-06-01

    The dream of interstellar flights persists since the first pioneers in astronautics and has never died. Many concepts of thruster capable to propel a rocket to the stars have been proposed and the most suitable among them are thought to be photon propulsion and propulsion by the products of proton-antiproton annihilation in magnetic nozzle. This article addresses both concepts allowing for cross-section of annihilation among other issues in order to show their vulnerability and to indicate the problems. The concept of relativistic matter propulsion is substantiated and discussed. The latter is argued to be the most straightforward way to build-up a relativistic rocket firstly because it is based on the existing technology of ion generators and accelerators and secondly because it can be stepped up in efflux power starting from interplanetary spacecrafts powered by nuclear reactors to interstellar starships powered by annihilation reactors. The problems imposed by thermodynamics and heat disposal are accentuated.

  17. Relativistic hydrodynamics on graphic cards

    NASA Astrophysics Data System (ADS)

    Gerhard, Jochen; Lindenstruth, Volker; Bleicher, Marcus

    2013-02-01

    We show how to accelerate relativistic hydrodynamics simulations using graphic cards (graphic processing units, GPUs). These improvements are of highest relevance e.g. to the field of high-energetic nucleus-nucleus collisions at RHIC and LHC where (ideal and dissipative) relativistic hydrodynamics is used to calculate the evolution of hot and dense QCD matter. The results reported here are based on the Sharp And Smooth Transport Algorithm (SHASTA), which is employed in many hydrodynamical models and hybrid simulation packages, e.g. the Ultrarelativistic Quantum Molecular Dynamics model (UrQMD). We have redesigned the SHASTA using the OpenCL computing framework to work on accelerators like graphic processing units (GPUs) as well as on multi-core processors. With the redesign of the algorithm the hydrodynamic calculations have been accelerated by a factor 160 allowing for event-by-event calculations and better statistics in hybrid calculations.

  18. Pythagoras Theorem and Relativistic Kinematics

    NASA Astrophysics Data System (ADS)

    Mulaj, Zenun; Dhoqina, Polikron

    2010-01-01

    In two inertial frames that move in a particular direction, may be registered a light signal that propagates in an angle with this direction. Applying Pythagoras theorem and principles of STR in both systems, we can derive all relativistic kinematics relations like the relativity of simultaneity of events, of the time interval, of the length of objects, of the velocity of the material point, Lorentz transformations, Doppler effect and stellar aberration.

  19. A realistic 3+1D Viscous Hydro Algorithm

    SciTech Connect

    Romatschke, Paul

    2015-05-31

    DoE funds were used as bridge funds for the faculty position for the PI at the University of Colorado. The total funds for the Years 3-5 of the JET Topical Collaboration amounted to about 50 percent of the academic year salary of the PI.The PI contributed to the JET Topical Collaboration by developing, testing and applying algorithms for a realistic simulation of the bulk medium created in relativistic ion collisions.Specifically, two approaches were studied, one based on a new Lattice-Boltzmann (LB) framework, and one on a more traditional viscous hydro-dynamics framework. Both approaches were found to be viable in principle, with the LB approach being more elegant but needing still more time to develop.The traditional approach led to the super-hybrid model of ion collisions dubbed 'superSONIC', and has been successfully used for phenomenology of relativistic heavy-ion and light-on-heavy-ion collisions.In the time-frame of the JET Topical Collaboration, the Colorado group has published 15 articles in peer-reviewed journals, three of which were published in Physical Review Letters. The group graduated one Master student during this time-frame and two more PhD students are expected to graduate in the next few years. The PI has given more than 28 talks and presentations during this period.

  20. Relativistic opacities for astrophysical applications

    DOE PAGES

    Fontes, Christopher John; Fryer, Christopher Lee; Hungerford, Aimee L.; Hakel, Peter; Colgan, James Patrick; Kilcrease, David Parker; Sherrill, Manalo Edgar

    2015-06-29

    Here, we report on the use of the Los Alamos suite of relativistic atomic physics codes to generate radiative opacities for the modeling of astrophysically relevant plasmas under local thermodynamic equilibrium (LTE) conditions. The atomic structure calculations are carried out in fine-structure detail, including full configuration interaction. Three example applications are considered: iron opacities at conditions relevant to the base of the solar convection zone, nickel opacities for the modeling of stellar envelopes, and samarium opacities for the modeling of light curves produced by neutron star mergers. In the first two examples, comparisons are made between opacities that are generatedmore » with the fully and semi-relativistic capabilities in the Los Alamos suite of codes. As expected for these highly charged, iron-peak ions, the two methods produce reasonably similar results, providing confidence that the numerical methods have been correctly implemented. However, discrepancies greater than 10% are observed for nickel and investigated in detail. In the final application, the relativistic capability is used in a preliminary investigation of the complicated absorption spectrum associated with cold lanthanide elements.« less

  1. Relativistic Tennis Using Flying Mirror

    SciTech Connect

    Pirozhkov, A. S.; Kando, M.; Ma, J.; Fukuda, Y.; Chen, L.-M.; Daito, I.; Ogura, K.; Homma, T.; Hayashi, Y.; Kotaki, H.; Sagisaka, A.; Mori, M.; Koga, J. K.; Kawachi, T.; Daido, H.; Kimura, T.; Kato, Y.; Tajima, T.; Esirkepov, T. Zh.; Bulanov, S. V.

    2008-06-24

    Upon reflection from a relativistic mirror, the electromagnetic pulse frequency is upshifted and the duration is shortened by the factor proportional to the relativistic gamma-factor squared due to the double Doppler effect. We present the results of the proof-of-principle experiment for frequency upshifting of the laser pulse reflected from the relativistic 'flying mirror', which is a wake wave near the breaking threshold created by a strong driver pulse propagating in underdense plasma. Experimentally, the wake wave is created by a 2 TW, 76 fs Ti:S laser pulse from the JLITE-X laser system in helium plasma with the electron density of {approx_equal}4-6x10{sup 19} cm{sup -3}. The reflected signal is observed with a grazing-incidence spectrograph in 24 shots. The wavelength of the reflected radiation ranges from 7 to 14 nm, the corresponding frequency upshifting factors are {approx}55-115, and the gamma-factors are y = 4-6. The reflected signal contains at least 3x10{sup 7} photons/sr. This effect can be used to generate coherent high-frequency ultrashort pulses that inherit temporal shape and polarization from the original (low-frequency) ones. Apart from this, the reflected radiation contains important information about the wake wave itself, e.g. location, size, phase velocity, etc.

  2. Relativistic Tennis Using Flying Mirror

    NASA Astrophysics Data System (ADS)

    Pirozhkov, A. S.; Kando, M.; Esirkepov, T. Zh.; Ma, J.; Fukuda, Y.; Chen, L.-M.; Daito, I.; Ogura, K.; Homma, T.; Hayashi, Y.; Kotaki, H.; Sagisaka, A.; Mori, M.; Koga, J. K.; Kawachi, T.; Daido, H.; Bulanov, S. V.; Kimura, T.; Kato, Y.; Tajima, T.

    2008-06-01

    Upon reflection from a relativistic mirror, the electromagnetic pulse frequency is upshifted and the duration is shortened by the factor proportional to the relativistic gamma-factor squared due to the double Doppler effect. We present the results of the proof-of-principle experiment for frequency upshifting of the laser pulse reflected from the relativistic "flying mirror", which is a wake wave near the breaking threshold created by a strong driver pulse propagating in underdense plasma. Experimentally, the wake wave is created by a 2 TW, 76 fs Ti:S laser pulse from the JLITE-X laser system in helium plasma with the electron density of ≈4-6×1019 cm-3. The reflected signal is observed with a grazing-incidence spectrograph in 24 shots. The wavelength of the reflected radiation ranges from 7 to 14 nm, the corresponding frequency upshifting factors are ˜55-115, and the gamma-factors are y = 4-6. The reflected signal contains at least 3×107 photons/sr. This effect can be used to generate coherent high-frequency ultrashort pulses that inherit temporal shape and polarization from the original (low-frequency) ones. Apart from this, the reflected radiation contains important information about the wake wave itself, e.g. location, size, phase velocity, etc.

  3. Numerical simulations of heavily polluted fine-grained sediment remobilization using 1D, 1D+, and 2D channel schematization.

    PubMed

    Kaiglová, Jana; Langhammer, Jakub; Jiřinec, Petr; Janský, Bohumír; Chalupová, Dagmar

    2015-03-01

    This article used various hydrodynamic and sediment transport models to analyze the potential and the limits of different channel schematizations. The main aim was to select and evaluate the most suitable simulation method for fine-grained sediment remobilization assessment. Three types of channel schematization were selected to study the flow potential for remobilizing fine-grained sediment in artificially modified channels. Schematization with a 1D cross-sectional horizontal plan, a 1D+ approach, splitting the riverbed into different functional zones, and full 2D mesh, adopted in MIKE by the DHI modeling suite, was applied to the study. For the case study, a 55-km stretch of the Bílina River, in the Czech Republic, Central Europe, which has been heavily polluted by the chemical and coal mining industry since the mid-twentieth century, was selected. Long-term exposure to direct emissions of toxic pollutants including heavy metals and persistent organic pollutants (POPs) resulted in deposits of pollutants in fine-grained sediments in the riverbed. Simulations, based on three hydrodynamic model schematizations, proved that for events not exceeding the extent of the riverbed profile, the 1D schematization can provide comparable results to a 2D model. The 1D+ schematization can improve accuracy while keeping the benefits of high-speed simulation and low requirements of input DEM data, but the method's suitability is limited by the channel properties. PMID:25687259

  4. Relativistic high harmonics and (sub-)attosecond pulses: relativistic spikes and relativistic mirror

    NASA Astrophysics Data System (ADS)

    Pukhov, A.; Baeva, T.; An der Brügge, D.; Münster, S.

    2009-11-01

    Using particle-in-cell simulations, we study high harmonic generation from overdense plasmas in the relativistic regime. Different incidence angles as well as different laser polarizations are considered and scalings are recovered. It is shown that the theory of relativistic spikes and the BGP power-law spectra [Phys. Rev. E 74, 046404 (2006)] describes well the normal incidence and s-polarized obliquely incident laser pulses. In the case of p-polarized laser pulses, exceptions from the BGP theory can appear when the quasi-static vector potential build-up at the plasma boundary becomes equal to that of the laser. In this case, the spectrum flattens significantly and has a lower cutoff.

  5. 1-D Numerical Analysis of ABCC Engine Performance

    NASA Technical Reports Server (NTRS)

    Holden, Richard

    1999-01-01

    ABCC engine combines air breathing and rocket engine into a single engine to increase the specific impulse over an entire flight trajectory. Except for the heat source, the basic operation of the ABCC is similar to the basic operation of the RBCC engine. The ABCC is intended to have a higher specific impulse than the RBCC for single stage Earth to orbit vehicle. Computational fluid dynamics (CFD) is a useful tool for the analysis of complex transport processes in various components in ABCC propulsion system. The objective of the present research was to develop a transient 1-D numerical model using conservation of mass, linear momentum, and energy equations that could be used to predict flow behavior throughout a generic ABCC engine following a flight path. At specific points during the development of the 1-D numerical model a myriad of tests were performed to prove the program produced consistent, realistic numbers that follow compressible flow theory for various inlet conditions.

  6. Phase diagram of a bulk 1d lattice Coulomb gas

    NASA Astrophysics Data System (ADS)

    Démery, V.; Monsarrat, R.; Dean, D. S.; Podgornik, R.

    2016-01-01

    The exact solution, via transfer matrix, of the simple one-dimensional lattice Coulomb gas (1d LCG) model can reproduce peculiar features of ionic liquid capacitors, such as overscreening, layering, and camel- and bell-shaped capacitance curves. Using the same transfer matrix method, we now compute the bulk properties of the 1d LCG in the constant voltage ensemble. We unveil a phase diagram with rich structure exhibiting low-density disordered and high-density ordered phases, separated by a first-order phase transition at low temperature; the solid state at full packing can be ordered or not, depending on the temperature. This phase diagram, which is strikingly similar to its three-dimensional counterpart, also sheds light on the behaviour of the confined system.

  7. 1D Josephson quantum interference grids: diffraction patterns and dynamics

    NASA Astrophysics Data System (ADS)

    Lucci, M.; Badoni, D.; Corato, V.; Merlo, V.; Ottaviani, I.; Salina, G.; Cirillo, M.; Ustinov, A. V.; Winkler, D.

    2016-02-01

    We investigate the magnetic response of transmission lines with embedded Josephson junctions and thus generating a 1D underdamped array. The measured multi-junction interference patterns are compared with the theoretical predictions for Josephson supercurrent modulations when an external magnetic field couples both to the inter-junction loops and to the junctions themselves. The results provide a striking example of the analogy between Josephson phase modulation and 1D optical diffraction grid. The Fiske resonances in the current-voltage characteristics with voltage spacing {Φ0}≤ft(\\frac{{\\bar{c}}}{2L}\\right) , where L is the total physical length of the array, {Φ0} the magnetic flux quantum and \\bar{c} the speed of light in the transmission line, demonstrate that the discrete line supports stable dynamic patterns generated by the ac Josephson effect interacting with the cavity modes of the line.

  8. Relativistic Navigation: A Theoretical Foundation

    NASA Technical Reports Server (NTRS)

    Turyshev, Slava G.

    1996-01-01

    We present a theoretical foundation for relativistic astronomical measurements in curved space-time. In particular, we discuss a new iterative approach for describing the dynamics of an isolated astronomical N-body system in metric theories of gravity. To do this, we generalize the Fock-Chandrasekhar method of the weak-field and slow-motion approximation (WFSMA) and develop a theory of relativistic reference frames (RF's) for a gravitationally bounded many-extended-body problem. In any proper RF constructed in the immediate vicinity of an arbitrary body, the N-body solutions of the gravitational field equations are formally presented as a sum of the Riemann-flat inertial space-time, the gravitational field generated by the body itself, the unperturbed solutions for each body in the system transformed to the coordinates of this proper RF, and the gravitational interaction term. We develop the basic concept of a general WFSMA theory of the celestial RF's applicable to a wide class of metric theories of gravity and an arbitrary model of matter distribution. We apply the proposed method to general relativity. Celestial bodies are described using a perfect fluid model; as such, they possess any number of internal mass and current multipole moments that explicitly characterize their internal structures. The obtained relativistic corrections to the geodetic equations of motion arise because of a coupling of the bodies' multiple moments to the surrounding gravitational field. The resulting relativistic transformations between the different RF's extend the Poincare group to the motion of deformable self-gravitating bodies. Within the present accuracy of astronomical measurements we discuss the properties of the Fermi-normal-like proper RF that is defined in the immediate vicinity of the extended compact bodies. We further generalize the proposed approximation method and include two Eddington parameters (gamma, Beta). This generalized approach was used to derive the

  9. Morphodynamics and sediment tracers in 1-D (MAST-1D): 1-D sediment transport that includes exchange with an off-channel sediment reservoir

    NASA Astrophysics Data System (ADS)

    Lauer, J. Wesley; Viparelli, Enrica; Piégay, Hervé

    2016-07-01

    Bed material transported in geomorphically active gravel bed rivers often has a local source at nearby eroding banks and ends up sequestered in bars not far downstream. However, most 1-D numerical models for gravel transport assume that gravel originates from and deposits on the channel bed. In this paper, we present a 1-D framework for simulating morphodynamic evolution of bed elevation and size distribution in a gravel-bed river that actively exchanges sediment with its floodplain, which is represented as an off-channel sediment reservoir. The model is based on the idea that sediment enters the channel at eroding banks whose elevation depends on total floodplain sediment storage and on the average elevation of the floodplain relative to the channel bed. Lateral erosion of these banks occurs at a specified rate that can represent either net channel migration or channel widening. Transfer of material out of the channel depends on a typical bar thickness and a specified lateral exchange rate due either to net channel migration or narrowing. The model is implemented using an object oriented framework that allows users to explore relationships between bank supply, bed structure, and lateral change rates. It is applied to a ∼50-km reach of the Ain River, France, that experienced significant reduction in sediment supply due to dam construction during the 20th century. Results are strongly sensitive to lateral exchange rates, showing that in this reach, the supply of sand and gravel at eroding banks and the sequestration of gravel in point bars can have strong influence on overall reach-scale sediment budgets.

  10. Relativistic radiation transport in dispersive media

    SciTech Connect

    Kichenassamy, S.; Krikorian, R.A.

    1985-10-15

    A general-relativistic radiative transfer equation in an isotropic, weakly absorbing, nonmagnetized dispersive medium is derived using the kinetic-theoretical approach and the relativistic Hamiltonian theory of geometrical optics in those media. It yields the generally accepted classical equation in the special-relativistic approximation and in stationary conditions. The influence of the gravitational field and of space-time variations of the refractive index n on the radiation distribution is made explicit in the case of spherical symmetry.

  11. Mesoscopic Superposition States in Relativistic Landau Levels

    SciTech Connect

    Bermudez, A.; Martin-Delgado, M. A.; Solano, E.

    2007-09-21

    We show that a linear superposition of mesoscopic states in relativistic Landau levels can be built when an external magnetic field couples to a relativistic spin 1/2 charged particle. Under suitable initial conditions, the associated Dirac equation produces unitarily superpositions of coherent states involving the particle orbital quanta in a well-defined mesoscopic regime. We demonstrate that these mesoscopic superpositions have a purely relativistic origin and disappear in the nonrelativistic limit.

  12. Free cooling on the Mediterranean shore: Energy efficiency upgrades at PIC

    NASA Astrophysics Data System (ADS)

    Acín, V.; Delfino, M.; Herbera, A.; Hernández, J.

    2015-12-01

    Energy consumption is an increasing concern for data centres. This paper summarizes recent energy efficiency upgrades at the Port d'Informacio Cientifica (PIC) in Barcelona, Spain which have considerably lowered energy consumption. The upgrades were particularly challenging, as they involved modifying the already existing machine room, which is shared by PIC with the general IT services of the Universitat Autonoma de Barcelona (UAB), with all the services in full operation, as well as the introduction of “free cooling” techniques in a location 20 km from the Mediterranean Sea. The upgrades targeted three distinct areas: First, the segregation of hot and cold air zones using an innovative horizontal layout, where hot air is channelled through openings in a false ceiling to a second story hot air plenum. This segregation allows increasing the cold air inlet temperature according to the latest ASHRAE recommendations. Second, the introduction of an outside air economizer which replaces obsolete CRAH systems with air-to-air heat exchangers. This system, built entirely from industrial components, also incorporates an adiabatic cooling module and enables the “free” removal of over 300 kW of IT heat load during 6000 hours a year. Third, the introduction of UPS systems based on IGBT technology, in order to better match the impedance characteristics of the IT load. In addition, a transversal activity has been done to fully integrate cooling and UPS infrastructure monitoring into PIC's overall IT monitoring framework based on Nagios. This required development of a ModBus/TCPIP gateway server.

  13. Spectral and Temporal Characteristics of LS PEG and TW PIC Using XMM-NEWTON Data

    NASA Astrophysics Data System (ADS)

    Talebpour Sheshvan, Nasrin; Balman, Solen

    2016-07-01

    We report the analysis of archival XMM-Newton X-ray observations of LS Peg and TW Pic. These are Cataclysmic Variables (CVs) suggested as Intermediate Polars (IPs), but unconfirmed in the X-rays. Identification of several periodic oscillations in the optical band hint them as IPs. Unlike the previous spectral analysis on the EPIC-MOS data by fitting a hot optically thin plasma emission model with a single temperature for LS Peg, we simultaneously fitted all EPIC spectrum (pn+MOS) using a composite model of absorption for interstellar medium (tbabs) with two different partial covering absorbers (pcfabs) including a multitemperature plasma emission component (cevmkl) and a Gaussian emission line at 6.4 keV. TW Pic is best modeled in a similar manner with only one partial covering absorber and an extra Gaussian emission line at 6.7 keV. LS Peg has a maximum plasma temperature of ˜14.8 keV with an X-ray luminosity of ˜5×10^{32}ergs ^{-1} translating to an accretion rate of ˜1.27×10^{-10}M _{⊙}yr ^{-1}. TW Pic shows kT _{max} ˜38.7 keV with an X-ray luminosity around 1.6×10^{33}ergs ^{-1} at an accretion rate of ˜4×10^{-10}M _{⊙}yr ^{-1}. In addition, we discuss orbital modulations in the X-rays and power spectral analysis, and derive the EPIC pn spectra for orbital minimum and orbital maximum phases for both sources. We elaborate on the geometry of accretion and absorption in the X-ray emitting regions of both sources with articulation on the magnetic nature.

  14. Enhancing Solar Cell Efficiencies through 1-D Nanostructures

    PubMed Central

    2009-01-01

    The current global energy problem can be attributed to insufficient fossil fuel supplies and excessive greenhouse gas emissions resulting from increasing fossil fuel consumption. The huge demand for clean energy potentially can be met by solar-to-electricity conversions. The large-scale use of solar energy is not occurring due to the high cost and inadequate efficiencies of existing solar cells. Nanostructured materials have offered new opportunities to design more efficient solar cells, particularly one-dimensional (1-D) nanomaterials for enhancing solar cell efficiencies. These 1-D nanostructures, including nanotubes, nanowires, and nanorods, offer significant opportunities to improve efficiencies of solar cells by facilitating photon absorption, electron transport, and electron collection; however, tremendous challenges must be conquered before the large-scale commercialization of such cells. This review specifically focuses on the use of 1-D nanostructures for enhancing solar cell efficiencies. Other nanostructured solar cells or solar cells based on bulk materials are not covered in this review. Major topics addressed include dye-sensitized solar cells, quantum-dot-sensitized solar cells, and p-n junction solar cells.

  15. Constructing 3D interaction maps from 1D epigenomes

    PubMed Central

    Zhu, Yun; Chen, Zhao; Zhang, Kai; Wang, Mengchi; Medovoy, David; Whitaker, John W.; Ding, Bo; Li, Nan; Zheng, Lina; Wang, Wei

    2016-01-01

    The human genome is tightly packaged into chromatin whose functional output depends on both one-dimensional (1D) local chromatin states and three-dimensional (3D) genome organization. Currently, chromatin modifications and 3D genome organization are measured by distinct assays. An emerging question is whether it is possible to deduce 3D interactions by integrative analysis of 1D epigenomic data and associate 3D contacts to functionality of the interacting loci. Here we present EpiTensor, an algorithm to identify 3D spatial associations within topologically associating domains (TADs) from 1D maps of histone modifications, chromatin accessibility and RNA-seq. We demonstrate that active promoter–promoter, promoter–enhancer and enhancer–enhancer associations identified by EpiTensor are highly concordant with those detected by Hi-C, ChIA-PET and eQTL analyses at 200 bp resolution. Moreover, EpiTensor has identified a set of interaction hotspots, characterized by higher chromatin and transcriptional activity as well as enriched TF and ncRNA binding across diverse cell types, which may be critical for stabilizing the local 3D interactions. PMID:26960733

  16. Constructing 3D interaction maps from 1D epigenomes.

    PubMed

    Zhu, Yun; Chen, Zhao; Zhang, Kai; Wang, Mengchi; Medovoy, David; Whitaker, John W; Ding, Bo; Li, Nan; Zheng, Lina; Wang, Wei

    2016-01-01

    The human genome is tightly packaged into chromatin whose functional output depends on both one-dimensional (1D) local chromatin states and three-dimensional (3D) genome organization. Currently, chromatin modifications and 3D genome organization are measured by distinct assays. An emerging question is whether it is possible to deduce 3D interactions by integrative analysis of 1D epigenomic data and associate 3D contacts to functionality of the interacting loci. Here we present EpiTensor, an algorithm to identify 3D spatial associations within topologically associating domains (TADs) from 1D maps of histone modifications, chromatin accessibility and RNA-seq. We demonstrate that active promoter-promoter, promoter-enhancer and enhancer-enhancer associations identified by EpiTensor are highly concordant with those detected by Hi-C, ChIA-PET and eQTL analyses at 200 bp resolution. Moreover, EpiTensor has identified a set of interaction hotspots, characterized by higher chromatin and transcriptional activity as well as enriched TF and ncRNA binding across diverse cell types, which may be critical for stabilizing the local 3D interactions. PMID:26960733

  17. Development of 1D Liner Compression Code for IDL

    NASA Astrophysics Data System (ADS)

    Shimazu, Akihisa; Slough, John; Pancotti, Anthony

    2015-11-01

    A 1D liner compression code is developed to model liner implosion dynamics in the Inductively Driven Liner Experiment (IDL) where FRC plasmoid is compressed via inductively-driven metal liners. The driver circuit, magnetic field, joule heating, and liner dynamics calculations are performed at each time step in sequence to couple these effects in the code. To obtain more realistic magnetic field results for a given drive coil geometry, 2D and 3D effects are incorporated into the 1D field calculation through use of correction factor table lookup approach. Commercial low-frequency electromagnetic fields solver, ANSYS Maxwell 3D, is used to solve the magnetic field profile for static liner condition at various liner radius in order to derive correction factors for the 1D field calculation in the code. The liner dynamics results from the code is verified to be in good agreement with the results from commercial explicit dynamics solver, ANSYS Explicit Dynamics, and previous liner experiment. The developed code is used to optimize the capacitor bank and driver coil design for better energy transfer and coupling. FRC gain calculations are also performed using the liner compression data from the code for the conceptual design of the reactor sized system for fusion energy gains.

  18. Experiments on a relativistic magnetron driven by a microsecond electron beam accelerator with a ceramic insulating stack

    NASA Astrophysics Data System (ADS)

    Lopez, Mike Rodriguez

    2003-10-01

    Relativistic magnetron experiments with a 6-vane, Titan tube have generated over 300 MW total microwave output power near 1 GHz. These experiments were driven by a long-pulse, e-beam accelerator. Parameters of the device were voltage = -0.3 to -0.4 MV, current = 1--10 kA, and pulselength = 0.5 microsecond. This body of work investigated pulse-shortening in the relativistic magnetron. Microwave generation with a conventional plastic insulator was compared to that with a new ceramic insulator. The ceramic insulator improved the vacuum by an order of magnitude (1 x 10-7 Torr) and increased voltage stability of the accelerator. The effect of RF breakdown in the waveguide on the intensity and duration of high power microwaves were also investigated. These experiments found that when SF6 gas was introduced into the waveguide, the measured efficiency, power, and pulselength of microwaves increased. Two different microwave extraction mechanisms were used. In the first system, two waveguides were connected to the magnetron pi-radians from each other. The second system used three waveguides to connect to the magnetron's extraction ports at 2pi/3 radians from each other. Microwaves were extracted into and measured from the waveguide. Pulselengths were found to be in the range of 10--200 ns. The theoretical investigation calculates the maximum injected current for a time-independent cycloidal flow in a relativistic, magnetically insulated diode. The analytical theory of Lovelace-Ott was extended by relaxing the space charge limited (SCL) assumption. This theory reduced to Christenson's results in the deeply non-relativistic regime, and to Lovelace-Ott under SCL. This theory has been successfully tested against relativistic PIC code simulations.

  19. Antibody response against plasmid-encoded toxin (Pet) and the protein involved in intestinal colonization (Pic) in children with diarrhea produced by enteroaggregative Escherichia coli.

    PubMed

    Bellini, Estela M; Elias, Waldir P; Gomes, Tânia A T; Tanaka, Tânia L; Taddei, Carla R; Huerta, Rocio; Navarro-Garcia, Fernando; Martinez, Marina B

    2005-02-01

    Enteroaggregative Escherichia coli (EAEC) is an emerging cause of pediatric and adult travellers diarrhea. The mechanism by which EAEC induce diarrhea is not completely known. Two serine protease autotransporter proteins, named Pet and Pic have been identified in EAEC strains. Pet has enterotoxic and cytotoxic activities, while the role of Pic in pathogenesis may lie on its mucinolytic activity. Little is known about Pet and Pic biological activities in vivo. In this study the antibody responses against these autotransporter proteins in convalescent children is investigated. Fifteen (83%) children showed specific antibodies against Pet or Pic in their sera. IgG and IgM antibodies were the main isotype found. Specific antibodies against Pic, but not against Pet, were detected in sera from age-matched control group. These data show that specific anti-Pet and anti-Pic antibodies are produced during the course of a natural EAEC infection in children.

  20. Dissipation in relativistic pair-plasma reconnection

    SciTech Connect

    Hesse, Michael; Zenitani, Seiji

    2007-11-15

    An investigation into the relativistic dissipation in magnetic reconnection is presented. The investigated system consists of an electron-positron plasma. A relativistic generalization of Ohm's law is derived. A set of numerical simulations is analyzed, composed of runs with and without guide magnetic field, and of runs with different species temperatures. The calculations indicate that the thermal inertia-based dissipation process survives in relativistic plasmas. For antiparallel reconnection, it is found that the pressure tensor divergence remains the sole contributor to the reconnection electric field, whereas relativistic guide field reconnection exhibits a similarly important role of the bulk inertia terms.

  1. Relativistic Bernstein waves in a degenerate plasma

    SciTech Connect

    Ali, Muddasir; Hussain, Azhar; Murtaza, G.

    2011-09-15

    Bernstein mode for a relativistic degenerate electron plasma is investigated. Using relativistic Vlasov-Maxwell equations, a general expression for the conductivity tensor is derived and then employing Fermi-Dirac distribution function a generalized dispersion relation for the Bernstein mode is obtained. Two limiting cases, i.e., non-relativistic and ultra-relativistic are discussed. The dispersion relations obtained are also graphically presented for some specific values of the parameters depicting how the propagation characteristics of Bernstein waves as well as the Upper Hybrid oscillations are modified with the increase in plasma number density.

  2. Dissipation in Relativistic Pair-Plasma Reconnection

    NASA Technical Reports Server (NTRS)

    Hesse, Michael; Zenitani, Seiji

    2007-01-01

    We present an investigation of the relativistic dissipation in magnetic reconnection. The investigated system consists of an electron-positron plasma. A relativistic generalization of Ohm's law is derived. We analyze a set of numerical simulations, composed of runs with and without guide magnetic field, and of runs with different species temperatures. The calculations indicate that the thermal inertia-based dissipation process survives in relativistic plasmas. For anti-parallel reconnection, it is found that the pressure tensor divergence remains the sole contributor to the reconnection electric field, whereas relativistic guide field reconnection exhibits a similarly important role of the bulk inertia terms.

  3. Taxonomic notes relating to Glenea diversenotata Schwarzer and G. quadriguttata Pic (Coleoptera, Cerambycidae, Lamiinae)

    PubMed Central

    Lin, Mei-Ying; Lingafelter, Steven W.

    2016-01-01

    Abstract Glenea diversenotata Schwarzer, 1925 is reinstated from a subspecies of Glenea tonkinea Aurivillius, 1925 to species level and Glenea neohumerosa Lin & Yang, 2011 is a new junior synonym. Some biological information on Glenea diversenotata is recorded for the first time, including pictures of the larva and pupa. Glenea quadriguttata Pic, 1926 is reinstated from a subspecies of Glenea lacteomaculata Schwarzer, 1925 to species level. Lectotypes for Glenea lacteomaculata and Glenea quadriguttata are designated. A modified key to the related species is presented. PMID:27199611

  4. A new species of Falsopodabrus Pic characterized with geometric morphometrics (Coleoptera, Cantharidae)

    PubMed Central

    Li, Limei; Qi, Yaqing; Yang, Yuxia; Bai, Ming

    2016-01-01

    Abstract A new species of Falsopodabrus Pic, 1927 is described, Falsopodabrus tridentatus Yang, sp. n. (Yunnan, China). Geometric morphometric analyses based on the shapes of pronotum and hind wing and comparisons with two sibling species, Falsopodabrus himalaicus Wittmer, 1974 and Falsopodabrus martensi (Wittmer, 1979), support the valid status of the new species, also confirmed by the characters of tarsal claws. In addition to Falsopodabrus himalaicus and Falsopodabrus martensi, Falsopodabrus kostali Švihla, 2004 and Falsopodabrus rolciki Švihla, 2004 are recorded from China for the first time.

  5. A new species of Falsopodabrus Pic characterized with geometric morphometrics (Coleoptera, Cantharidae).

    PubMed

    Li, Limei; Qi, Yaqing; Yang, Yuxia; Bai, Ming

    2016-01-01

    A new species of Falsopodabrus Pic, 1927 is described, Falsopodabrus tridentatus Yang, sp. n. (Yunnan, China). Geometric morphometric analyses based on the shapes of pronotum and hind wing and comparisons with two sibling species, Falsopodabrus himalaicus Wittmer, 1974 and Falsopodabrus martensi (Wittmer, 1979), support the valid status of the new species, also confirmed by the characters of tarsal claws. In addition to Falsopodabrus himalaicus and Falsopodabrus martensi, Falsopodabrus kostali Švihla, 2004 and Falsopodabrus rolciki Švihla, 2004 are recorded from China for the first time. PMID:27667934

  6. A new species of Falsopodabrus Pic characterized with geometric morphometrics (Coleoptera, Cantharidae).

    PubMed

    Li, Limei; Qi, Yaqing; Yang, Yuxia; Bai, Ming

    2016-01-01

    A new species of Falsopodabrus Pic, 1927 is described, Falsopodabrus tridentatus Yang, sp. n. (Yunnan, China). Geometric morphometric analyses based on the shapes of pronotum and hind wing and comparisons with two sibling species, Falsopodabrus himalaicus Wittmer, 1974 and Falsopodabrus martensi (Wittmer, 1979), support the valid status of the new species, also confirmed by the characters of tarsal claws. In addition to Falsopodabrus himalaicus and Falsopodabrus martensi, Falsopodabrus kostali Švihla, 2004 and Falsopodabrus rolciki Švihla, 2004 are recorded from China for the first time.

  7. CCD images of Mars with the 1 M reflector atop Pic-du-Midi

    NASA Astrophysics Data System (ADS)

    Lecacheux, J.; Drossart, P.; Buil, C.; Laques, P.; Thouvenot, E.; Guerin, P.

    1991-02-01

    CCD images of high spatial resolution, in red filters near 800 nm, have been taken from the 1 m reflector of Pic-du-Midi Observatory during the opposition of Mars, between August and October 1988. In several of the images a bright elongated feature is observed with a longitudinal extension of more than 100 deg. Comparison with Viking mosaics shows that small variations of albedo may be attributed to wind transportation of surface deposits by the strong winds of Mars. Small changes observed between the 2 months observation may be attributed to localized dust clouds on Mars.

  8. A new species of Falsopodabrus Pic characterized with geometric morphometrics (Coleoptera, Cantharidae)

    PubMed Central

    Li, Limei; Qi, Yaqing; Yang, Yuxia; Bai, Ming

    2016-01-01

    Abstract A new species of Falsopodabrus Pic, 1927 is described, Falsopodabrus tridentatus Yang, sp. n. (Yunnan, China). Geometric morphometric analyses based on the shapes of pronotum and hind wing and comparisons with two sibling species, Falsopodabrus himalaicus Wittmer, 1974 and Falsopodabrus martensi (Wittmer, 1979), support the valid status of the new species, also confirmed by the characters of tarsal claws. In addition to Falsopodabrus himalaicus and Falsopodabrus martensi, Falsopodabrus kostali Švihla, 2004 and Falsopodabrus rolciki Švihla, 2004 are recorded from China for the first time. PMID:27667934

  9. Taxonomic notes relating to Glenea diversenotata Schwarzer and G. quadriguttata Pic (Coleoptera, Cerambycidae, Lamiinae).

    PubMed

    Lin, Mei-Ying; Lingafelter, Steven W

    2016-01-01

    Glenea diversenotata Schwarzer, 1925 is reinstated from a subspecies of Glenea tonkinea Aurivillius, 1925 to species level and Glenea neohumerosa Lin & Yang, 2011 is a new junior synonym. Some biological information on Glenea diversenotata is recorded for the first time, including pictures of the larva and pupa. Glenea quadriguttata Pic, 1926 is reinstated from a subspecies of Glenea lacteomaculata Schwarzer, 1925 to species level. Lectotypes for Glenea lacteomaculata and Glenea quadriguttata are designated. A modified key to the related species is presented. PMID:27199611

  10. Molecular characterization of zebrafish Oatp1d1 (Slco1d1), a novel organic anion-transporting polypeptide.

    PubMed

    Popovic, Marta; Zaja, Roko; Fent, Karl; Smital, Tvrtko

    2013-11-22

    The organic anion-transporting polypeptide (OATP/Oatp) superfamily includes a group of polyspecific transporters that mediate transport of large amphipathic, mostly anionic molecules across cell membranes of eukaryotes. OATPs/Oatps are involved in the disposition and elimination of numerous physiological and foreign compounds. However, in non-mammalian species, the functional properties of Oatps remain unknown. We aimed to elucidate the role of Oatp1d1 in zebrafish to gain insights into the functional and structural evolution of the OATP1/Oatp1 superfamily. We show that diversification of the OATP1/Oatp1 family occurs after the emergence of jawed fish and that the OATP1A/Oatp1a and OATP1B/Oatp1b subfamilies appeared at the root of tetrapods. The Oatp1d subfamily emerged in teleosts and is absent in tetrapods. The zebrafish Oatp1d1 is similar to mammalian OATP1A/Oatp1a and OATP1B/Oatp1b members, with the main physiological role in transport and balance of steroid hormones. Oatp1d1 activity is dependent upon pH gradient, which could indicate bicarbonate exchange as a mode of transport. Our analysis of evolutionary conservation and structural properties revealed that (i) His-79 in intracellular loop 3 is conserved within OATP1/Oatp1 family and is crucial for the transport activity; (ii) N-glycosylation impacts membrane targeting and is conserved within the OATP1/Oatp1 family with Asn-122, Asn-133, Asn-499, and Asn-512 residues involved; (iii) the evolutionarily conserved cholesterol recognition interaction amino acid consensus motif is important for membrane localization; and (iv) Oatp1d1 is present in dimeric and possibly oligomeric form in the cell membrane. In conclusion, we describe the first detailed characterization of a new Oatp transporter in zebrafish, offering important insights into the functional evolution of the OATP1/Oatp1 family and the physiological role of Oatp1d1.

  11. Relativistic and non-relativistic solitons in plasmas

    NASA Astrophysics Data System (ADS)

    Barman, Satyendra Nath

    This thesis entitled as "Relativistic and Non-relativistic Solitons in Plasmas" is the embodiment of a number of investigations related to the formation of ion-acoustic solitary waves in plasmas under various physical situations. The whole work of the thesis is devoted to the studies of solitary waves in cold and warm collisionless magnetized or unmagnetized plasmas with or without relativistic effect. To analyze the formation of solitary waves in all our models of plasmas, we have employed two established methods namely - reductive perturbation method to deduce the Korteweg-de Vries (KdV) equation, the solutions of which represent the important but near exact characteristic concepts of soliton-physics. Next, the pseudopotential method to deduce the energy integral with total nonlinearity in the coupling process for exact characteristic results of solitons has been incorporated. In Chapter 1, a brief description of plasma in nature and laboratory and its generation are outlined elegantly. The nonlinear differential equations to characterize solitary waves and the relevant but important methods of solutions have been mentioned in this chapter. The formation of solitary waves in unmagnetized and magnetized plasmas, and in relativistic plasmas has been described through mathematical entity. Applications of plasmas in different fields are also put forwarded briefly showing its importance. The study of plasmas as they naturally occur in the universe encompasses number of topics including sun's corona, solar wind, planetary magnetospheres, ionospheres, auroras, cosmic rays and radiation. The study of space weather to understand the universe, communications and the activities of weather satellites are some useful areas of space plasma physics. The surface cleaning, sterilization of food and medical appliances, killing of bacteria on various surfaces, destroying of viruses, fungi, spores and plasma coating in industrial instruments ( like computers) are some of the fields

  12. Grid-based Methods in Relativistic Hydrodynamics and Magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Martí, José María; Müller, Ewald

    2015-12-01

    An overview of grid-based numerical methods used in relativistic hydrodynamics (RHD) and magnetohydrodynamics (RMHD) is presented. Special emphasis is put on a comprehensive review of the application of high-resolution shock-capturing methods. Results of a set of demanding test bench simulations obtained with different numerical methods are compared in an attempt to assess the present capabilities and limits of the various numerical strategies. Applications to three astrophysical phenomena are briefly discussed to motivate the need for and to demonstrate the success of RHD and RMHD simulations in their understanding. The review further provides FORTRAN programs to compute the exact solution of the Riemann problem in RMHD, and to simulate 1D RMHD flows in Cartesian coordinates.

  13. Relativistic Corrections to the Bohr Model of the Atom

    ERIC Educational Resources Information Center

    Kraft, David W.

    1974-01-01

    Presents a simple means for extending the Bohr model to include relativistic corrections using a derivation similar to that for the non-relativistic case, except that the relativistic expressions for mass and kinetic energy are employed. (Author/GS)

  14. Magnetogenesis through Relativistic Velocity Shear

    NASA Astrophysics Data System (ADS)

    Miller, Evan

    Magnetic fields at all scales are prevalent in our universe. However, current cosmological models predict that initially the universe was bereft of large-scale fields. Standard magnetohydrodynamics (MHD) does not permit magnetogenesis; in the MHD Faraday's law, the change in magnetic field B depends on B itself. Thus if B is initially zero, it will remain zero for all time. A more accurate physical model is needed to explain the origins of the galactic-scale magnetic fields observed today. In this thesis, I explore two velocity-driven mechanisms for magnetogenesis in 2-fluid plasma. The first is a novel kinematic 'battery' arising from convection of vorticity. A coupling between thermal and plasma oscillations, this non-relativistic mechanism can operate in flows that are incompressible, quasi-neutral and barotropic. The second mechanism results from inclusion of thermal effects in relativistic shear flow instabilities. In such flows, parallel perturbations are ubiquitously unstable at small scales, with growth rates of order with the plasma frequency over a defined range of parameter-space. Of these two processes, instabilities seem far more likely to account for galactic magnetic fields. Stable kinematic effects will, at best, be comparable to an ideal Biermann battery, which is suspected to be orders of magnitude too weak to produce the observed galactic fields. On the other hand, instabilities grow until saturation is reached, a topic that has yet to be explored in detail on cosmological scales. In addition to investigating these magnetogenesis sources, I derive a general dispersion relation for three dimensional, warm, two species plasma with discontinuous shear flow. The mathematics of relativistic plasma, sheared-flow instability and the Biermann battery are also discussed.

  15. Relativistic electromagnetic ion cyclotron instabilities.

    PubMed

    Chen, K R; Huang, R D; Wang, J C; Chen, Y Y

    2005-03-01

    The relativistic instabilities of electromagnetic ion cyclotron waves driven by MeV ions are analytically and numerically studied. As caused by wave magnetic field and in sharp contrast to the electrostatic case, interesting characteristics such as Alfve nic behavior and instability transition are discovered and illuminated in detail. The instabilities are reactive and are raised from the coupling of slow ions' first-order resonance and fast ions' second-order resonance, that is an essential extra mechanism due to relativistic effect. Because of the wave magnetic field, the nonresonant plasma dielectric is usually negative and large, that affects the instability conditions and scaling laws. A negative harmonic cyclotron frequency mismatch between the fast and slow ions is required for driving a cubic (and a coupled quadratic) instability; the cubic (square) root scaling of the peak growth rate makes the relativistic effect more important than classical mechanism, especially for low fast ion density and Lorentz factor being close to unity. For the cubic instability, there is a threshold (ceiling) on the slow ion temperature and density (the external magnetic field and the fast ion energy); the Alfve n velocity is required to be low. This Alfve nic behavior is interesting in physics and important for its applications. The case of fast protons in thermal deuterons is numerically studied and compared with the analytical results. When the slow ion temperature or density (the external magnetic field or the fast ion energy) is increased (reduced) to about twice (half) the threshold (ceiling), the same growth rate peak transits from the cubic instability to the coupled quadratic instability and a different cubic instability branch appears. The instability transition is an interesting new phenomenon for instability. PMID:15903591

  16. Relativistic radiative transfer and relativistic spherical shell flows

    NASA Astrophysics Data System (ADS)

    Fukue, Jun

    2016-06-01

    We examine a radiatively driven spherical flow from a central object, whose thickness is smaller than the radius of the central object, and a plane-parallel approximation can be used-a spherical shell flow. We first solve the relativistic radiative transfer equation iteratively, using a given velocity field, and obtain specific intensities as well as moment quantities. Using the obtained comoving flux, we then solve the relativistic hydrodynamical equation, and obtain a new velocity field. We repeat these double iteration processes until both the intensity and velocity profiles converge. We found that the flow speed v(τ) is roughly approximated as β ≡ v/c = βs(1 - τ/τb), where τ is the optical depth, τb the flow total optical depth, and c the speed of light. We further found that the flow terminal speed vs is roughly expressed as β _s ≡ v_s/c = (Γ hat{F}_0-1)τ_b/dot{m} , where Γ is the central luminosity normalized by the Eddington luminosity, hat{F}_0 the comoving flux normalized by the incident flux, and of the order of unity, and dot{m} the mass-loss rate normalized by the critical mass loss.

  17. Thermodynamics of polarized relativistic matter

    NASA Astrophysics Data System (ADS)

    Kovtun, Pavel

    2016-07-01

    We give the free energy of equilibrium relativistic matter subject to external gravitational and electromagnetic fields, to one-derivative order in the gradients of the external fields. The free energy allows for a straightforward derivation of bound currents and bound momenta in equilibrium. At leading order, the energy-momentum tensor admits a simple expression in terms of the polarization tensor. Beyond the leading order, electric and magnetic polarization vectors are intrinsically ambiguous. The physical effects of polarization, such as the correlation between the magneto-vortically induced surface charge and the electro-vortically induced surface current, are not ambiguous.

  18. Relativistic atomic beam spectroscopy II

    SciTech Connect

    1989-12-31

    The negative ion of H is one of the simplest 3-body atomic systems. The techniques we have developed for experimental study of atoms moving near speed of light have been productive. This proposal request continuing support for experimental studies of the H{sup -} system, principally at the 800 MeV linear accelerator (LAMPF) at Los Alamos. Four experiments are currently planned: photodetachment of H{sup -} near threshold in electric field, interaction of relativistic H{sup -} ions with matter, high excitations and double charge escape in H{sup -}, and multiphoton detachment of electrons from H{sup -}.

  19. Relativistic mean-field theory

    NASA Astrophysics Data System (ADS)

    Meng, Jie; Ring, Peter; Zhao, Pengwei

    In this chapter, the covariant energy density functional is constructed with both the meson-exchange and the point-coupling pictures. Several widely used functionals with either nonlinear or density-dependent effective interactions are introduced. The applications of covariant density functional theory are demonstrated for infinite nuclear matter and finite nuclei with spherical symmetry, axially symmetric quadrupole deformation, and triaxial quadrupole shapes. Finally, a relativistic description of the nuclear landscape has been discussed, which is not only important for nuclear structure, but also important for nuclear astrophysics, where we are facing the problem of a reliable extrapolation to the very neutron-rich nuclei.

  20. Relativistic quantum private database queries

    NASA Astrophysics Data System (ADS)

    Sun, Si-Jia; Yang, Yu-Guang; Zhang, Ming-Ou

    2015-04-01

    Recently, Jakobi et al. (Phys Rev A 83, 022301, 2011) suggested the first practical private database query protocol (J-protocol) based on the Scarani et al. (Phys Rev Lett 92, 057901, 2004) quantum key distribution protocol. Unfortunately, the J-protocol is just a cheat-sensitive private database query protocol. In this paper, we present an idealized relativistic quantum private database query protocol based on Minkowski causality and the properties of quantum information. Also, we prove that the protocol is secure in terms of the user security and the database security.

  1. Einstein Toolkit for Relativistic Astrophysics

    NASA Astrophysics Data System (ADS)

    Collaborative Effort

    2011-02-01

    The Einstein Toolkit is a collection of software components and tools for simulating and analyzing general relativistic astrophysical systems. Such systems include gravitational wave space-times, collisions of compact objects such as black holes or neutron stars, accretion onto compact objects, core collapse supernovae and Gamma-Ray Bursts. The Einstein Toolkit builds on numerous software efforts in the numerical relativity community including CactusEinstein, Whisky, and Carpet. The Einstein Toolkit currently uses the Cactus Framework as the underlying computational infrastructure that provides large-scale parallelization, general computational components, and a model for collaborative, portable code development.

  2. Relativistic kinematics and stationary motions

    NASA Astrophysics Data System (ADS)

    Russo, Jorge G.; Townsend, Paul K.

    2009-11-01

    The relativistic jerk, snap and all higher-order kinematical D-vectors are defined for the motion of a massive particle in a D-dimensional Minkowski spacetime. We illustrate the formalism with stationary motions, for which we provide a new, Lorentz covariant, classification. We generalize some cases to branes, explaining the relevance to uniform motion in a heat bath. We also consider some non-stationary motions, including motion with constant proper jerk, and free fall into a black hole as viewed from a GEMS perspective.

  3. PIC simulations of whistler wave generation using plasma conditions from the RAM-SCB model

    NASA Astrophysics Data System (ADS)

    Yu, Yiqun; Zhao, Lei; Peng, Bo; Delzanno, Gian Luca; Jordanova, Vania; Markidis, Stefano

    2014-10-01

    Wave-particle interactions play an important role in the Earth's inner magnetospheric dynamics. We study the whistler wave generation with an implicit particle-in-cell code (iPIC3D) within unstable equatorial regions identified by the kinetic ring current model RAM-SCB. During storm time, RAM-SCB shows that hot electrons on the dayside demonstrate high temperature anisotropy and are unstable to whistler wave excitation. By using plasma parameters from RAM-SCB, we carry out iPIC3D simulations assuming a bi-Maxwellian distribution for electrons. We find that with an electron temperature anisotropy of 4, electron density of 6 cm-3, and parallel temperature of 1 keV on the dayside around L ~ 5 . 5 , whistler waves are rapidly excited and propagate along the background magnetic field. Comparisons with linear theory show good agreement. The electron velocity distribution is significantly changed after wave generation, with smaller anisotropy due to the pitch-angle scattering. Furthermore, test particles are tracked in the whistler wave environment and the pitch-angle diffusion coefficient is extracted. The coefficient generally agrees with quasi-linear theory prediction with slight deviation even when the wave amplitude is as large as 5 % of the background magnetic field.

  4. Properties of lower-hybrid range wave activity at reconnection jet edge: 3D PIC simulations

    NASA Astrophysics Data System (ADS)

    Divin, Andrey; Khotyaintsev, Yuri; Vaivads, Andris; Andre, Mats; Lapenta, Giovanni; Markidis, Stefano

    2014-05-01

    Reconnection fronts are areas of intense currents and enhanced wave activity, since magnetic flux and plasma are piled up there when the accelerated flow encounters denser ambient current sheet. Observations and numerical simulations show that the fronts generate a variety of waves ranging from MHD frequencies up to lower hybrid frequency and above. In the present study we use 2D and 3D Particle-in-Cell (PIC) simulations to investigate the properties of the lower hybrid range waves developing at hot reconnected plasma - current sheet interface. Calculations are performed using implicit parallel code iPIC3D starting from conventional Harris current sheet. Initial evolution of the jet is simulated using 2D approach to save computational time, but 3D calculations are implemented at later stages in order to observe instability linear stage, saturation and transition to turbulence. Properties of the linear stage match closely theoretical predictions for the lower hybrid drift instability. During saturation, the mode produces intense electric fields (several Alfvén in electric fields normalized unit) that can provide an additional mechanism of electron heating at reconnection jet fronts.

  5. Orbital Constraints on the (beta) Pic Inner Planet Candidate with Keck Adaptive Optics

    SciTech Connect

    Fitzgerald, M P; Kalas, P G; Graham, J R

    2009-09-23

    A point source observed 8AU in projection from {beta} Pictoris in L{prime} (3.8 {micro}m) imaging in 2003 has been recently presented as a planet candidate. Here we show the results of L{prime}-band adaptive optics imaging obtained at Keck Observatory in 2008. We do not detect {beta} Pic b beyond a limiting radius of 0.29-inch, or 5.5AU in projection, from the star. If {beta} Pic b is an orbiting planet, then it has moved {ge} 0.12-inch (2.4AU in projection) closer to the star in the five years separating the two epochs of observation. We examine the range of orbital parameters consistent with the observations, including likely bounds from the locations of previously inferred planetesimal belts. We find a family of low-eccentricity orbits with semimajor axes {approx} 8-9AU that are completely allowed, as well as a broad region of orbits with e {approx}< 0.2, a {approx}> 10AU that are allowed if the apparent motion of the planet was towards the star in 2003. We compare this allowed space with predictions of the planetary orbital elements from the literature. Additionally, we show how similar observations in the next several years can further constrain the space of allowed orbits. Non-detections of the source through 2013 will exclude the interpretation of the candidate as a planet orbiting between the 6.4 and 16AU planetesimal belts.

  6. Food-pics: an image database for experimental research on eating and appetite.

    PubMed

    Blechert, Jens; Meule, Adrian; Busch, Niko A; Ohla, Kathrin

    2014-01-01

    Our current environment is characterized by the omnipresence of food cues. The sight and smell of real foods, but also graphically depictions of appetizing foods, can guide our eating behavior, for example, by eliciting food craving and influencing food choice. The relevance of visual food cues on human information processing has been demonstrated by a growing body of studies employing food images across the disciplines of psychology, medicine, and neuroscience. However, currently used food image sets vary considerably across laboratories and image characteristics (contrast, brightness, etc.) and food composition (calories, macronutrients, etc.) are often unspecified. These factors might have contributed to some of the inconsistencies of this research. To remedy this, we developed food-pics, a picture database comprising 568 food images and 315 non-food images along with detailed meta-data. A total of N = 1988 individuals with large variance in age and weight from German speaking countries and North America provided normative ratings of valence, arousal, palatability, desire to eat, recognizability and visual complexity. Furthermore, data on macronutrients (g), energy density (kcal), and physical image characteristics (color composition, contrast, brightness, size, complexity) are provided. The food-pics image database is freely available under the creative commons license with the hope that the set will facilitate standardization and comparability across studies and advance experimental research on the determinants of eating behavior.

  7. PIC/MCC simulation of capacitively coupled discharges: Effect of particle management and integration

    NASA Astrophysics Data System (ADS)

    Sun, Anbang; Becker, Markus M.; Loffhagen, Detlef

    2016-09-01

    A PIC/MCC simulation model for the analysis of low-temperature discharge plasmas is represented which takes the common leapfrog and the velocity Verlet algorithm for the particle integration, adaptive particle management as well as parallel computing using MPI into account. Main features of the model including the impact of super particle numbers, adaptive particle management and the time step size for the different integration methods are represented. The investigations are performed for low-pressure capacitively coupled radio frequency discharges in helium and argon. Besides a code verification by comparison with benchmark simulation results in helium it is shown that an adaptive particle management is particularly suitable for the simulation of discharges at elevated pressures where boundary effects and processes in the sheath regions are important. Furthermore, it is pointed out that the velocity Verlet integration scheme allows to speed up the PIC/MCC simulations compared to the leapfrog method because it makes the use of larger time steps at the same accuracy possible.

  8. Effects from switching on PIC simulations: Geospace Environmental Modeling (GEM) reconnection setup revisited

    NASA Astrophysics Data System (ADS)

    Bourdin, P. A.; Nakamura, T.; Narita, Y.

    2015-12-01

    Electromagnetic Parcile-In-Cell (PIC) simulations are widely used to study plasma phenomena where kinetic scales are coupled to fluid scales. One of these phenomena is the evolution of magnetic reconnection. Switch-on effects have been described earlier for magneto-/hydrodynamic (MHD and HD) simulations, where oscillations are ignited by the initial condition and the usual instantaneous way of starting a simulation run. Here we revisit the GEM setup (a Harris current sheet) and demonstrate the immediate generation of oscillations propagating perpendicular to the magnetic shear layer (in Bz). Also we show how these oscillations do not dissipate quickly and will later be mode-converted to generate wave power, first in By, much later also in Bx (pointing along the shear direction). One needs to take care not to interpret these oscillations as physical wave modes associated with the nature of reconnection. We propose a method to prevent such switch-on effects from the beginning, that should be considered for implementation in other PIC simulation codes as well.

  9. Pathway-Informed Classification System (PICS) for Cancer Analysis Using Gene Expression Data.

    PubMed

    Young, Michael R; Craft, David L

    2016-01-01

    We introduce Pathway-Informed Classification System (PICS) for classifying cancers based on tumor sample gene expression levels. PICS is a computational method capable of expeditiously elucidating both known and novel biological pathway involvement specific to various cancers and uses that learned pathway information to separate patients into distinct classes. The method clearly separates a pan-cancer dataset by tissue of origin and also sub-classifies individual cancer datasets into distinct survival classes. Gene expression values are collapsed into pathway scores that reveal which biological activities are most useful for clustering cancer cohorts into subtypes. Variants of the method allow it to be used on datasets that do and do not contain noncancerous samples. Activity levels of all types of pathways, broadly grouped into metabolic, cellular processes and signaling, and immune system, are useful for separating the pan-cancer cohort. In the clustering of specific cancer types, certain pathway types become more valuable depending on the site being studied. For lung cancer, signaling pathways dominate; for pancreatic cancer, signaling and metabolic pathways dominate; and for melanoma, immune system pathways are the most useful. This work suggests the utility of pathway-level genomic analysis and points in the direction of using pathway classification for predicting the efficacy and side effects of drugs and radiation.

  10. Multi-scale simulations of space problems with iPIC3D

    NASA Astrophysics Data System (ADS)

    Lapenta, Giovanni; Bettarini, Lapo; Markidis, Stefano

    The implicit Particle-in-Cell method for the computer simulation of space plasma, and its im-plementation in a three-dimensional parallel code, called iPIC3D, are presented. The implicit integration in time of the Vlasov-Maxwell system removes the numerical stability constraints and enables kinetic plasma simulations at magnetohydrodynamics scales. Simulations of mag-netic reconnection in plasma are presented to show the effectiveness of the algorithm. In particular we will show a number of simulations done for large scale 3D systems using the physical mass ratio for Hydrogen. Most notably one simulation treats kinetically a box of tens of Earth radii in each direction and was conducted using about 16000 processors of the Pleiades NASA computer. The work is conducted in collaboration with the MMS-IDS theory team from University of Colorado (M. Goldman, D. Newman and L. Andersson). Reference: Stefano Markidis, Giovanni Lapenta, Rizwan-uddin Multi-scale simulations of plasma with iPIC3D Mathematics and Computers in Simulation, Available online 17 October 2009, http://dx.doi.org/10.1016/j.matcom.2009.08.038

  11. pic gene of enteroaggregative Escherichia coli and its association with diarrhea in Peruvian children.

    PubMed

    Durand, David; Contreras, Carmen A; Mosquito, Susan; Ruíz, Joaquim; Cleary, Thomas G; Ochoa, Theresa J

    2016-08-01

    Enteroaggregative Escherichia coli (EAEC) causes acute and persistent diarrhea among children, HIV-infected patients, and travelers to developing countries. We have searched for 18 genes-encoding virulence factors associated with aggregative adherence, dispersion, biofilm, toxins, serine protease autotransporters of Enterobacteriaceae (SPATEs) and siderophores, analyzed in 172 well-characterized EAEC strains (aggR(+)) isolated from stool samples of 97 children with diarrhea and 75 healthy controls from a passive surveillance diarrhea cohort study in Peru. Eighty-one different genetic profiles were identified, 37 were found only associated with diarrhea and 25 with control samples. The most frequent genetic profile was aggC(+)aatA(+)aap(+)shf(+)fyuA(+), present in 19 strains, including diarrhea and controls. The profile set1A(+)set1B(+)pic(+) was associated with diarrhea (P < 0.05). Of all genes evaluated, the most frequent were aatA (CVD 342) present in 159 strains (92.4%) and fyuA in 157 (91.3%). When EAEC strains were analyzed as a single pathogen (excluding co-infections), only pic was associated with diarrhea (P < 0.05) and with prolonged diarrhea (diarrhea ≥ 7 days) (P < 0.05). In summary, this is the first report on the prevalence of a large set of EAEC virulence genes and its association with diarrhea in Peruvian children. More studies are needed to elucidate the exact role of each virulence factor.

  12. Food-pics: an image database for experimental research on eating and appetite.

    PubMed

    Blechert, Jens; Meule, Adrian; Busch, Niko A; Ohla, Kathrin

    2014-01-01

    Our current environment is characterized by the omnipresence of food cues. The sight and smell of real foods, but also graphically depictions of appetizing foods, can guide our eating behavior, for example, by eliciting food craving and influencing food choice. The relevance of visual food cues on human information processing has been demonstrated by a growing body of studies employing food images across the disciplines of psychology, medicine, and neuroscience. However, currently used food image sets vary considerably across laboratories and image characteristics (contrast, brightness, etc.) and food composition (calories, macronutrients, etc.) are often unspecified. These factors might have contributed to some of the inconsistencies of this research. To remedy this, we developed food-pics, a picture database comprising 568 food images and 315 non-food images along with detailed meta-data. A total of N = 1988 individuals with large variance in age and weight from German speaking countries and North America provided normative ratings of valence, arousal, palatability, desire to eat, recognizability and visual complexity. Furthermore, data on macronutrients (g), energy density (kcal), and physical image characteristics (color composition, contrast, brightness, size, complexity) are provided. The food-pics image database is freely available under the creative commons license with the hope that the set will facilitate standardization and comparability across studies and advance experimental research on the determinants of eating behavior. PMID:25009514

  13. Pathway-Informed Classification System (PICS) for Cancer Analysis Using Gene Expression Data

    PubMed Central

    Young, Michael R; Craft, David L

    2016-01-01

    We introduce Pathway-Informed Classification System (PICS) for classifying cancers based on tumor sample gene expression levels. PICS is a computational method capable of expeditiously elucidating both known and novel biological pathway involvement specific to various cancers and uses that learned pathway information to separate patients into distinct classes. The method clearly separates a pan-cancer dataset by tissue of origin and also sub-classifies individual cancer datasets into distinct survival classes. Gene expression values are collapsed into pathway scores that reveal which biological activities are most useful for clustering cancer cohorts into subtypes. Variants of the method allow it to be used on datasets that do and do not contain noncancerous samples. Activity levels of all types of pathways, broadly grouped into metabolic, cellular processes and signaling, and immune system, are useful for separating the pan-cancer cohort. In the clustering of specific cancer types, certain pathway types become more valuable depending on the site being studied. For lung cancer, signaling pathways dominate; for pancreatic cancer, signaling and metabolic pathways dominate; and for melanoma, immune system pathways are the most useful. This work suggests the utility of pathway-level genomic analysis and points in the direction of using pathway classification for predicting the efficacy and side effects of drugs and radiation. PMID:27486299

  14. 2D electrostatic PIC algorithm for laser induced studying plasma in vacuum

    NASA Astrophysics Data System (ADS)

    Álvarez, C. A.; Riascos, H.; Gonzalez, C.

    2016-02-01

    Particle-In-Cell(PIC) method is widely used for simulating plasma kinetic models. A 2D-PIC electrostatic algorithm is implemented for simulating the expansion of a laser- induced plasma plume. For potential and Electric Field calculation, Dirichlet and periodic boundary conditions are used in the X (perpendicular to the ablated material) and Y directions, respectively. Poisson-solver employs FFTW3 library and the five-point Laplacian to compute the electric potential. Electric field calculation is made by central finite differences method. Leap-frog scheme updates particle positions and velocities at each iteration. Plume expansion anlysis is done for the Emission and Post-Emission stages. In the Emission phase (while the laser is turned on), fast electron expansion is observed and ion particles remain near the surface of the ablated material. In the post-emission stage (with the laser turned off) the charge separation produces an electric field that accelerates the ions leading to the formation of a KeV per particle Ion-Front. At the end of the expansion, fastest electrons escape from the simulation space; an almost homogeneous ion-electron distribution is observed, decreasing the electric field value and the Coulomb interactions.

  15. Extended-Range Ultrarefractive 1D Photonic Crystal Prisms

    NASA Technical Reports Server (NTRS)

    Ting, David Z.

    2007-01-01

    A proposal has been made to exploit the special wavelength-dispersive characteristics of devices of the type described in One-Dimensional Photonic Crystal Superprisms (NPO-30232) NASA Tech Briefs, Vol. 29, No. 4 (April 2005), page 10a. A photonic crystal is an optical component that has a periodic structure comprising two dielectric materials with high dielectric contrast (e.g., a semiconductor and air), with geometrical feature sizes comparable to or smaller than light wavelengths of interest. Experimental superprisms have been realized as photonic crystals having three-dimensional (3D) structures comprising regions of amorphous Si alternating with regions of SiO2, fabricated in a complex process that included sputtering. A photonic crystal of the type to be exploited according to the present proposal is said to be one-dimensional (1D) because its contrasting dielectric materials would be stacked in parallel planar layers; in other words, there would be spatial periodicity in one dimension only. The processes of designing and fabricating 1D photonic crystal superprisms would be simpler and, hence, would cost less than do those for 3D photonic crystal superprisms. As in 3D structures, 1D photonic crystals may be used in applications such as wavelength-division multiplexing. In the extended-range configuration, it is also suitable for spectrometry applications. As an engineered structure or artificially engineered material, a photonic crystal can exhibit optical properties not commonly found in natural substances. Prior research had revealed several classes of photonic crystal structures for which the propagation of electromagnetic radiation is forbidden in certain frequency ranges, denoted photonic bandgaps. It had also been found that in narrow frequency bands just outside the photonic bandgaps, the angular wavelength dispersion of electromagnetic waves propagating in photonic crystal superprisms is much stronger than is the angular wavelength dispersion obtained

  16. Non-linearity in Bayesian 1-D magnetotelluric inversion

    NASA Astrophysics Data System (ADS)

    Guo, Rongwen; Dosso, Stan E.; Liu, Jianxin; Dettmer, Jan; Tong, Xiaozhong

    2011-05-01

    This paper applies a Bayesian approach to examine non-linearity for the 1-D magnetotelluric (MT) inverse problem. In a Bayesian formulation the posterior probability density (PPD), which combines data and prior information, is interpreted in terms of parameter estimates and uncertainties, which requires optimizing and integrating the PPD. Much work on 1-D MT inversion has been based on (approximate) linearized solutions, but more recently fully non-linear (numerical) approaches have been applied. This paper directly compares results of linearized and non-linear uncertainty estimation for 1-D MT inversion; to do so, advanced methods for both approaches are applied. In the non-linear formulation used here, numerical optimization is carried out using an adaptive-hybrid algorithm. Numerical integration applies Metropolis-Hastings sampling, rotated to a principal-component parameter space for efficient sampling of correlated parameters, and employing non-unity sampling temperatures to ensure global sampling. Since appropriate model parametrizations are generally not known a priori, both under- and overparametrized approaches are considered. For underparametrization, the Bayesian information criterion is applied to determine the number of layers consistent with the resolving power of the data. For overparametrization, prior information is included which favours simple structure in a manner similar to regularized inversion. The data variance and/or trade-off parameter regulating data and prior information are treated in several ways, including applying fixed optimal estimates (an empirical Bayesian approach) or including them as hyperparameters in the sampling (hierarchical Bayesian). The latter approach has the benefit of accounting for the uncertainty in the hyperparameters in estimating model parameter uncertainties. Non-linear and linearized inversion results are compared for synthetic test cases and for the measured COPROD1 MT data by considering marginal probability

  17. Viscous behavior in a quasi-1D fractal cluster glass.

    PubMed

    Etzkorn, S J; Hibbs, Wendy; Miller, Joel S; Epstein, A J

    2002-11-11

    The spin glass transition of a quasi-1D organic-based magnet ([MnTPP][TCNE]) is explored using both ac and dc measurements. A scaling analysis of the ac susceptibility shows a spin glass transition near 4 K, with a viscous decay of the thermoremanent magnetization recorded above 4 K. We propose an extension to a fractal cluster model of spin glasses that determines the dimension of the spin clusters (D) ranging from approximately 0.8 to over 1.5 as the glass transition is approached. Long-range dipolar interactions are suggested as the origin of this low value for the apparent lower critical dimension.

  18. Practical variational tomography for critical 1D systems

    NASA Astrophysics Data System (ADS)

    Lee, Jong Yeon; Landon-Cardinal, Olivier

    2015-03-01

    We further investigate a recently introduced efficient quantum state reconstruction procedure targeted to states well-approximated by the multi-scale entanglement renormalization ansatz (MERA). First, we introduce an improved optimization scheme that can be easily generalized for MERA states with larger bond dimension. Second, we provide a detailed analysis of the error propagation and quantify how it affects the distance between the experimental state and the reconstructed state. Third, we explain how to bound this distance using local data, providing an efficient scalable certification method. Fourth, we examine the performance of MERA tomography on the ground states of several 1D critical models.

  19. Structural stability of a 1D compressible viscoelastic fluid model

    NASA Astrophysics Data System (ADS)

    Huo, Xiaokai; Yong, Wen-An

    2016-07-01

    This paper is concerned with a compressible viscoelastic fluid model proposed by Öttinger. Although the model has a convex entropy, the Hessian matrix of the entropy does not symmetrize the system of first-order partial differential equations due to the non-conservative terms in the constitutive equation. We show that the corresponding 1D model is symmetrizable hyperbolic and dissipative and satisfies the Kawashima condition. Based on these, we prove the global existence of smooth solutions near equilibrium and justify the compatibility of the model with the Navier-Stokes equations.

  20. Nonlocal Order Parameters for the 1D Hubbard Model

    NASA Astrophysics Data System (ADS)

    Montorsi, Arianna; Roncaglia, Marco

    2012-12-01

    We characterize the Mott-insulator and Luther-Emery phases of the 1D Hubbard model through correlators that measure the parity of spin and charge strings along the chain. These nonlocal quantities order in the corresponding gapped phases and vanish at the critical point Uc=0, thus configuring as hidden order parameters. The Mott insulator consists of bound doublon-holon pairs, which in the Luther-Emery phase turn into electron pairs with opposite spins, both unbinding at Uc. The behavior of the parity correlators is captured by an effective free spinless fermion model.

  1. Deconvolution/identification techniques for 1-D transient signals

    SciTech Connect

    Goodman, D.M.

    1990-10-01

    This paper discusses a variety of nonparametric deconvolution and identification techniques that we have developed for application to 1-D transient signal problems. These methods are time-domain techniques that use direct methods for matrix inversion. Therefore, they are not appropriate for large data'' problems. These techniques involve various regularization methods and permit the use of certain kinds of a priori information in estimating the unknown. These techniques have been implemented in a package using standard FORTRAN that should make the package readily transportable to most computers. This paper is also meant to be an instruction manual for the package. 25 refs., 17 figs., 1 tab.

  2. Coherent thermal conductance of 1-D photonic crystals

    NASA Astrophysics Data System (ADS)

    Tschikin, Maria; Ben-Abdallah, Philippe; Biehs, Svend-Age

    2012-10-01

    We present an exact calculation of coherent thermal conductance in 1-D multilayer photonic crystals using the S-matrix method. In particular, we study the thermal conductance in a bilayer structure of Si/vacuum or Al2O3/vacuum slabs by means of the exact radiative heat flux expression. Based on the results obtained for the Al2O3/vacuum structure we show by comparison with previous works that the material losses and (localized) surface modes supported by the inner layers play a fundamental role and cannot be omitted in the definition of thermal conductance. Our results could have significant implications in the conception of efficient thermal barriers.

  3. Recent advances in high-performance modeling of plasma-based acceleration using the full PIC method

    NASA Astrophysics Data System (ADS)

    Vay, J.-L.; Lehe, R.; Vincenti, H.; Godfrey, B. B.; Haber, I.; Lee, P.

    2016-09-01

    Numerical simulations have been critical in the recent rapid developments of plasma-based acceleration concepts. Among the various available numerical techniques, the particle-in-cell (PIC) approach is the method of choice for self-consistent simulations from first principles. The fundamentals of the PIC method were established decades ago, but improvements or variations are continuously being proposed. We report on several recent advances in PIC-related algorithms that are of interest for application to plasma-based accelerators, including (a) detailed analysis of the numerical Cherenkov instability and its remediation for the modeling of plasma accelerators in laboratory and Lorentz boosted frames, (b) analytic pseudo-spectral electromagnetic solvers in Cartesian and cylindrical (with azimuthal modes decomposition) geometries, and (c) novel analysis of Maxwell's solvers' stencil variation and truncation, in application to domain decomposition strategies and implementation of perfectly matched layers in high-order and pseudo-spectral solvers.

  4. Performance of the micro-PIC gaseous area detector in small-angle X-ray scattering experiments.

    PubMed

    Hattori, Kaori; Tsuchiya, Ken'ichi; Ito, Kazuki; Okada, Yoko; Fujii, Kotaro; Kubo, Hidetoshi; Miuchi, Kentaro; Takata, Masaki; Tanimori, Toru; Uekusa, Hidehiro

    2009-03-01

    The application of a two-dimensional photon-counting detector based on a micro-pixel gas chamber (micro-PIC) to high-resolution small-angle X-ray scattering (SAXS), and its performance, are reported. The micro-PIC is a micro-pattern gaseous detector fabricated by printed circuit board technology. This article describes the performance of the micro-PIC in SAXS experiments at SPring-8. A dynamic range of >10(5) was obtained for X-ray scattering from a polystyrene sphere solution. A maximum counting rate of up to 5 MHz was observed with good linearity and without saturation. For a diffraction pattern of collagen, weak peaks were observed in the high-angle region in one accumulation of photons.

  5. Magnetism and rotation in relativistic field theory

    NASA Astrophysics Data System (ADS)

    Mameda, Kazuya; Yamamoto, Arata

    2016-09-01

    We investigate the analogy between magnetism and rotation in relativistic theory. In nonrelativistic theory, the exact correspondence between magnetism and rotation is established in the presence of an external trapping potential. Based on this, we analyze relativistic rotation under external trapping potentials. A Landau-like quantization is obtained by considering an energy-dependent potential.

  6. Compton Effect with Non-Relativistic Kinematics

    ERIC Educational Resources Information Center

    Shivalingaswamy, T.; Kagali, B. A.

    2011-01-01

    In deducing the change of wavelength of x-rays scattered by atomic electrons, one normally makes use of relativistic kinematics for electrons. However, recoiling energies of the electrons are of the order of a few keV which is less than 0.2% of their rest energies. Hence the authors may ask whether relativistic formulae are really necessary. In…

  7. Einstein Never Approved of Relativistic Mass

    ERIC Educational Resources Information Center

    Hecht, Eugene

    2009-01-01

    During much of the 20th century it was widely believed that one of the significant insights of special relativity was "relativistic mass." Today there are two schools on that issue: the traditional view that embraces speed-dependent "relativistic mass," and the more modern position that rejects it, maintaining that there is only one mass and it's…

  8. Nonlinear, relativistic Langmuir waves in astrophysical magnetospheres

    NASA Technical Reports Server (NTRS)

    Chian, Abraham C.-L.

    1987-01-01

    Large amplitude, electrostatic plasma waves are relevant to physical processes occurring in the astrophysical magnetospheres wherein charged particles are accelerated to relativistic energies by strong waves emitted by pulsars, quasars, or radio galaxies. The nonlinear, relativistic theory of traveling Langmuir waves in a cold plasma is reviewed. The cases of streaming electron plasma, electronic plasma, and two-streams are discussed.

  9. Electron and ion acceleration in relativistic shocks with applications to GRB afterglows

    NASA Astrophysics Data System (ADS)

    Warren, Donald C.; Ellison, Donald C.; Bykov, Andrei M.; Lee, Shiu-Hang

    2015-09-01

    We have modelled the simultaneous first-order Fermi shock acceleration of protons, electrons, and helium nuclei by relativistic shocks. By parametrizing the particle diffusion, our steady-state Monte Carlo simulation allows us to follow particles from particle injection at non-relativistic thermal energies to above PeV energies, including the non-linear smoothing of the shock structure due to cosmic ray (CR) backpressure. We observe the mass-to-charge (A/Z) enhancement effect believed to occur in efficient Fermi acceleration in non-relativistic shocks and we parametrize the transfer of ion energy to electrons seen in particle-in-cell (PIC) simulations. For a given set of environmental and model parameters, the Monte Carlo simulation determines the absolute normalization of the particle distributions and the resulting synchrotron, inverse Compton, and pion-decay emission in a largely self-consistent manner. The simulation is flexible and can be readily used with a wide range of parameters typical of γ-ray burst (GRB) afterglows. We describe some preliminary results for photon emission from shocks of different Lorentz factors and outline how the Monte Carlo simulation can be generalized and coupled to hydrodynamic simulations of GRB blast waves. We assume Bohm diffusion for simplicity but emphasize that the non-linear effects we describe stem mainly from an extended shock precursor where higher energy particles diffuse further upstream. Quantitative differences will occur with different diffusion models, particularly for the maximum CR energy and photon emission, but these non-linear effects should be qualitatively similar as long as the scattering mean-free path is an increasing function of momentum.

  10. Relativistic Definition of Spin Operators

    NASA Astrophysics Data System (ADS)

    Ryder, Lewis H.

    2002-12-01

    Some years ago Mashhoon [1] made the highly interesting suggestion that there existed a coupling of spin with rotations, just as there exists such a coupling with orbital angular momentum, as seen in the Sagnac effect, for example. Spin being essentially a quantum phenomenon, the obvious place to look for this was by studying the Dirac equation, and Hehl and Ni, in such an investigation [2], indeed found a coupling term of just the type Mashhoon had envisaged. Part of their procedure, however, was to take the nonrelativistic limit, and this was done by performing appropriate Foldy-Wouthuysen (FW) transformations. In the nonrelativistic limit, it is well-known that the spin operators for Dirac particles are in essence the Pauli matrices; but it is also well-known, and indeed was part of the motivation for Foldy and Wouthuysen's paper, that for fully-fledged Dirac particles the (4×4 generalisation of the) Pauli matrices do not yield satisfactory spin operators, since spin defined in this way would not be conserved. The question therefore presented itself: is there a relativistic spin operator for Dirac particles, such that in the relativistic, as well as the nonrelativistic, régime a Mashhoon spin-rotation coupling exists?...

  11. Single electron relativistic clock interferometer

    NASA Astrophysics Data System (ADS)

    Bushev, P. A.; Cole, J. H.; Sholokhov, D.; Kukharchyk, N.; Zych, M.

    2016-09-01

    Although time is one of the fundamental notions in physics, it does not have a unique description. In quantum theory time is a parameter ordering the succession of the probability amplitudes of a quantum system, while according to relativity theory each system experiences in general a different proper time, depending on the system's world line, due to time dilation. It is therefore of fundamental interest to test the notion of time in the regime where both quantum and relativistic effects play a role, for example, when different amplitudes of a single quantum clock experience different magnitudes of time dilation. Here we propose a realization of such an experiment with a single electron in a Penning trap. The clock can be implemented in the electronic spin precession and its time dilation then depends on the radial (cyclotron) state of the electron. We show that coherent manipulation and detection of the electron can be achieved already with present day technology. A single electron in a Penning trap is a technologically ready platform where the notion of time can be probed in a hitherto untested regime, where it requires a relativistic as well as quantum description.

  12. 24-Hour Relativistic Bit Commitment

    NASA Astrophysics Data System (ADS)

    Verbanis, Ephanielle; Martin, Anthony; Houlmann, Raphaël; Boso, Gianluca; Bussières, Félix; Zbinden, Hugo

    2016-09-01

    Bit commitment is a fundamental cryptographic primitive in which a party wishes to commit a secret bit to another party. Perfect security between mistrustful parties is unfortunately impossible to achieve through the asynchronous exchange of classical and quantum messages. Perfect security can nonetheless be achieved if each party splits into two agents exchanging classical information at times and locations satisfying strict relativistic constraints. A relativistic multiround protocol to achieve this was previously proposed and used to implement a 2-millisecond commitment time. Much longer durations were initially thought to be insecure, but recent theoretical progress showed that this is not so. In this Letter, we report on the implementation of a 24-hour bit commitment solely based on timed high-speed optical communication and fast data processing, with all agents located within the city of Geneva. This duration is more than 6 orders of magnitude longer than before, and we argue that it could be extended to one year and allow much more flexibility on the locations of the agents. Our implementation offers a practical and viable solution for use in applications such as digital signatures, secure voting and honesty-preserving auctions.

  13. Non-relativistic scale anomalies

    NASA Astrophysics Data System (ADS)

    Arav, Igal; Chapman, Shira; Oz, Yaron

    2016-06-01

    We extend the cohomological analysis in arXiv:1410.5831 of anisotropic Lifshitz scale anomalies. We consider non-relativistic theories with a dynamical critical exponent z = 2 with or without non-relativistic boosts and a particle number symmetry. We distinguish between cases depending on whether the time direction does or does not induce a foliation structure. We analyse both 1 + 1 and 2 + 1 spacetime dimensions. In 1 + 1 dimensions we find no scale anomalies with Galilean boost symmetries. The anomalies in 2 + 1 dimensions with Galilean boosts and a foliation structure are all B-type and are identical to the Lifshitz case in the purely spatial sector. With Galilean boosts and without a foliation structure we find also an A-type scale anomaly. There is an infinite ladder of B-type anomalies in the absence of a foliation structure with or without Galilean boosts. We discuss the relation between the existence of a foliation structure and the causality of the field theory.

  14. Relativistic Non-Thermal Bremsstrahlung Radiation

    NASA Astrophysics Data System (ADS)

    Zeković, Vladimir; Arbutina, Bojan; Dobardžić, Aleksandra; Pavlović, Marko Z.

    2013-11-01

    By applying a method of virtual quanta we derive formulae for relativistic non-thermal bremsstrahlung radiation from relativistic electrons as well as from protons and heavier particles with power-law momentum distribution N(p)dp = k p-qdp. We show that emission which originates from an electron scattering on an ion, represents the most significant component of relativistic non-thermal bremsstrahlung. Radiation from an ion scattering on electron, known as inverse bremsstrahlung, is shown to be negligible in overall non-thermal bremsstrahlung emission. These results arise from theory refinement, where we introduce the dependence of relativistic kinetic energy of an incident particle, upon the energy of scattered photon. In part, it is also a consequence of a different mass of particles and relativistic effects.

  15. Relativistic electron and ion dust charging currents

    SciTech Connect

    Tribeche, Mouloud; Boukhalfa, Soufiane

    2009-09-15

    A first theoretical attempt is made to present a relativistic generalization of the well-known orbit-limited motion theory. The appropriate relativistic (electron and ion) dust charging currents are derived. The nonlinear electrostatic potential is then expressed in terms of the variable dust charge and we take advantage of this new transcendental relation to investigate briefly the effects of relativistic charge carriers. As the relativistic character of the plasma increases, it becomes evident that certain negative values of the dust charge can never be achieved as increasingly larger values of the nonlinear potential are involved. The obtained formulas bring a possibility to build theories of nonlinear collective process in relativistic dusty plasmas.

  16. A simple quasi-1D model of Fibonacci anyons

    NASA Astrophysics Data System (ADS)

    Aasen, David; Mong, Roger; Clarke, David; Alicea, Jason; Fendley, Paul

    2015-03-01

    There exists various ways of understanding the topological properties of Ising anyons--from simple free-fermion toy models to formal topological quantum field theory. For other types of anyons simple toy models rarely exist; their properties have to be obtained using formal self-consistency relations. We explore a family of gapped 1D local bosonic models that in a certain limit become trivial to solve and provide an intuitive picture for Fibonacci anyons. One can interpret this model as a quasi-1D wire that forms the building block of a 2D topological phase with Fibonacci anyons. With this interpretation all topological properties of the Fibonacci anyons become manifest including ground state degeneracy and braid relations. We conjecture that the structure of the model is protected by an emergent symmetry analogous to fermion parity. 1) NSF Grant DMR-1341822 2) Institute for Quantum Information and Matter, an NSF physics frontier center with support from the Moore Foundation. 3) NSERC-PGSD.

  17. A 1D analysis of two high order MOC methods

    SciTech Connect

    Everson, M. S.; Forget, B.

    2012-07-01

    The work presented here provides two different methods for evaluating angular fluxes along long characteristics. One is based off a projection of the 1D transport equation onto a complete set of Legendre polynomials, while the other uses the 1D integral transport equation to evaluate the angular flux values at specific points along each track passing through a cell. The Moment Long Characteristic (M-LC) method is shown to provide 2(P+1) spatial convergence and significant gains in accuracy with the addition of only a few spatial degrees of freedom. The M-LC method, though, is shown to be ill-conditioned at very high order and for optically thin geometries. The Point Long Characteristic (P-LC) method, while less accurate, significantly improves stability to problems with optically thin cells. The P-LC method is also more flexible, allowing for extra angular flux evaluations along a given track to give a more accurate representation of the shape along each track. This is at the expense of increasing the degrees of freedom of the system, though, and requires an increase in memory storage. This work concludes that both may be used simultaneously within the same geometry to provide the best mix of accuracy and stability possible. (authors)

  18. Engineered atom-light interactions in 1D photonic crystals

    NASA Astrophysics Data System (ADS)

    Martin, Michael J.; Hung, Chen-Lung; Yu, Su-Peng; Goban, Akihisa; Muniz, Juan A.; Hood, Jonathan D.; Norte, Richard; McClung, Andrew C.; Meenehan, Sean M.; Cohen, Justin D.; Lee, Jae Hoon; Peng, Lucas; Painter, Oskar; Kimble, H. Jeff

    2014-05-01

    Nano- and microscale optical systems offer efficient and scalable quantum interfaces through enhanced atom-field coupling in both resonators and continuous waveguides. Beyond these conventional topologies, new opportunities emerge from the integration of ultracold atomic systems with nanoscale photonic crystals. One-dimensional photonic crystal waveguides can be engineered for both stable trapping configurations and strong atom-photon interactions, enabling novel cavity QED and quantum many-body systems, as well as distributed quantum networks. We present the experimental realization of such a nanophotonic quantum interface based on a nanoscale photonic crystal waveguide, demonstrating a fractional waveguide coupling of Γ1 D /Γ' of 0 . 32 +/- 0 . 08 , where Γ1 D (Γ') is the atomic emission rate into the guided (all other) mode(s). We also discuss progress towards intra-waveguide trapping of ultracold Cs. This work was supported by the IQIM, an NSF Physics Frontiers Center with support from the Moore Foundation, the DARPA ORCHID program, the AFOSR QuMPASS MURI, the DoD NSSEFF program, NSF, and the Kavli Nanoscience Institute (KNI) at Caltech.

  19. Analysis of the beam halo in negative ion sources by using 3D3V PIC code.

    PubMed

    Miyamoto, K; Nishioka, S; Goto, I; Hatayama, A; Hanada, M; Kojima, A; Hiratsuka, J

    2016-02-01

    The physical mechanism of the formation of the negative ion beam halo and the heat loads of the multi-stage acceleration grids are investigated with the 3D PIC (particle in cell) simulation. The following physical mechanism of the beam halo formation is verified: The beam core and the halo consist of the negative ions extracted from the center and the periphery of the meniscus, respectively. This difference of negative ion extraction location results in a geometrical aberration. Furthermore, it is shown that the heat loads on the first acceleration grid and the second acceleration grid are quantitatively improved compared with those for the 2D PIC simulation result.

  20. Characterization of a trinuclear ruthenium species in catalytic water oxidation by Ru(bda)(pic)2 in neutral media.

    PubMed

    Zhang, Biaobiao; Li, Fei; Zhang, Rong; Ma, Chengbing; Chen, Lin; Sun, Licheng

    2016-06-30

    A Ru(III)-O-Ru(IV)-O-Ru(III) type trinuclear species was crystallographically characterized in water oxidation by Ru(bda)(pic)2 (H2bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; pic = 4-picoline) under neutral conditions. The formation of a ruthenium trimer due to the reaction of Ru(IV)[double bond, length as m-dash]O with Ru(II)-OH2 was fully confirmed by chemical, electrochemical and photochemical methods. Since the oxidation of the trimer was proposed to lead to catalyst decomposition, the photocatalytic water oxidation activity was rationally improved by the suppression of the formation of the trimer.

  1. Analysis of the beam halo in negative ion sources by using 3D3V PIC code.

    PubMed

    Miyamoto, K; Nishioka, S; Goto, I; Hatayama, A; Hanada, M; Kojima, A; Hiratsuka, J

    2016-02-01

    The physical mechanism of the formation of the negative ion beam halo and the heat loads of the multi-stage acceleration grids are investigated with the 3D PIC (particle in cell) simulation. The following physical mechanism of the beam halo formation is verified: The beam core and the halo consist of the negative ions extracted from the center and the periphery of the meniscus, respectively. This difference of negative ion extraction location results in a geometrical aberration. Furthermore, it is shown that the heat loads on the first acceleration grid and the second acceleration grid are quantitatively improved compared with those for the 2D PIC simulation result. PMID:26932006

  2. Proton acceleration in the electrostatic sheaths of hot electrons governed by strongly relativistic laser-absorption processes.

    PubMed

    Ter-Avetisyan, S; Schnürer, M; Sokollik, T; Nickles, P V; Sandner, W; Reiss, H R; Stein, J; Habs, D; Nakamura, T; Mima, K

    2008-01-01

    Two different laser energy absorption mechanisms at the front side of a laser-irradiated foil have been found to occur, such that two distinct relativistic electron beams with different properties are produced. One beam arises from the ponderomotively driven electrons propagating in the laser propagation direction, and the other is the result of electrons driven by resonance absorption normal to the target surface. These properties become evident at the rear surface of the target, where they give rise to two spatially separated sources of ions with distinguishable characteristics when ultrashort (40fs) high-intensity laser pulses irradiate a foil at 45 degrees incidence. The laser pulse intensity and the contrast ratio are crucial. One can establish conditions such that one or the other of the laser energy absorption mechanisms is dominant, and thereby one can control the ion acceleration scenarios. The observations are confirmed by particle-in-cell (PIC) simulations.

  3. Simulations of Dynamic Relativistic Magnetospheres

    NASA Astrophysics Data System (ADS)

    Parfrey, Kyle Patrick

    Neutron stars and black holes are generally surrounded by magnetospheres of highly conducting plasma in which the magnetic flux density is so high that hydrodynamic forces are irrelevant. In this vanishing-inertia—or ultra-relativistic—limit, magnetohydrodynamics becomes force-free electrodynamics, a system of equations comprising only the magnetic and electric fields, and in which the plasma response is effected by a nonlinear current density term. In this dissertation I describe a new pseudospectral simulation code, designed for studying the dynamic magnetospheres of compact objects. A detailed description of the code and several numerical test problems are given. I first apply the code to the aligned rotator problem, in which a star with a dipole magnetic field is set rotating about its magnetic axis. The solution evolves to a steady state, which is nearly ideal and dissipationless everywhere except in a current sheet, or magnetic field discontinuity, at the equator, into which electromagnetic energy flows and is dissipated. Magnetars are believed to have twisted magnetospheres, due to internal magnetic evolution which deforms the crust, dragging the footpoints of external magnetic field lines. This twisting may be able to explain both magnetars' persistent hard X-ray emission and their energetic bursts and flares. Using the new code, I simulate the evolution of relativistic magnetospheres subjected to slow twisting through large angles. The field lines expand outward, forming a strong current layer; eventually the configuration loses equilibrium and a dynamic rearrangement occurs, involving large-scale rapid magnetic reconnection and dissipation of the free energy of the twisted magnetic field. When the star is rotating, the magnetospheric twisting leads to a large increase in the stellar spin-down rate, which may take place on the long twisting timescale or in brief explosive events, depending on where the twisting is applied and the history of the system

  4. Terahertz radiation driven by two-color laser pulses at near-relativistic intensities: Competition between photoionization and wakefield effects

    NASA Astrophysics Data System (ADS)

    González de Alaiza Martínez, P.; Davoine, X.; Debayle, A.; Gremillet, L.; Bergé, L.

    2016-06-01

    We numerically investigate terahertz (THz) pulse generation by linearly-polarized, two-color femtosecond laser pulses in highly-ionized argon. Major processes consist of tunneling photoionization and ponderomotive forces associated with transverse and longitudinal field excitations. By means of two-dimensional particle-in-cell (PIC) simulations, we reveal the importance of photocurrent mechanisms besides transverse and longitudinal plasma waves for laser intensities >1015 W/cm2. We demonstrate the following. (i) With two-color pulses, photoionization prevails in the generation of GV/m THz fields up to 1017 W/cm2 laser intensities and suddenly loses efficiency near the relativistic threshold, as the outermost electron shell of ionized Ar atoms has been fully depleted. (ii) PIC results can be explained by a one-dimensional Maxwell-fluid model and its semi-analytical solutions, offering the first unified description of the main THz sources created in plasmas. (iii) The THz power emitted outside the plasma channel mostly originates from the transverse currents.

  5. Terahertz radiation driven by two-color laser pulses at near-relativistic intensities: Competition between photoionization and wakefield effects.

    PubMed

    González de Alaiza Martínez, P; Davoine, X; Debayle, A; Gremillet, L; Bergé, L

    2016-01-01

    We numerically investigate terahertz (THz) pulse generation by linearly-polarized, two-color femtosecond laser pulses in highly-ionized argon. Major processes consist of tunneling photoionization and ponderomotive forces associated with transverse and longitudinal field excitations. By means of two-dimensional particle-in-cell (PIC) simulations, we reveal the importance of photocurrent mechanisms besides transverse and longitudinal plasma waves for laser intensities >10(15) W/cm(2). We demonstrate the following. (i) With two-color pulses, photoionization prevails in the generation of GV/m THz fields up to 10(17) W/cm(2) laser intensities and suddenly loses efficiency near the relativistic threshold, as the outermost electron shell of ionized Ar atoms has been fully depleted. (ii) PIC results can be explained by a one-dimensional Maxwell-fluid model and its semi-analytical solutions, offering the first unified description of the main THz sources created in plasmas. (iii) The THz power emitted outside the plasma channel mostly originates from the transverse currents. PMID:27255689

  6. Mechanism of phase control in a klystron-like relativistic backward wave oscillator by an input signal

    SciTech Connect

    Xiao, Renzhen; Song, Zhimin; Deng, Yuqun; Chen, Changhua

    2014-09-15

    Theoretical analyses and particle-in-cell (PIC) simulations are carried out to understand the mechanism of microwave phase control realized by the external RF signal in a klystron-like relativistic backward wave oscillator (RBWO). Theoretical calculations show that a modulated electron beam can lead the microwave field with an arbitrary initial phase to the same equilibrium phase, which is determined by the phase factor of the modulated current, and the difference between them is fixed. Furthermore, PIC simulations demonstrate that the phase of input signal has a close relation to that of modulated current, which initiates the phase of the irregularly microwave during the build-up of oscillation. Since the microwave field is weak during the early time of starting oscillation, it is easy to be induced, and a small input signal is sufficient to control the phase of output microwave. For the klystron-like RBWO with two pre-modulation cavities and a reentrant input cavity, an input signal with 100 kW power and 4.21 GHz frequency can control the phase of 5 GW output microwave with relative phase difference less than 6% when the diode voltage is 760 kV, and beam current is 9.8 kA, corresponding to a power ratio of output microwave to input signal of 47 dB.

  7. Terahertz radiation driven by two-color laser pulses at near-relativistic intensities: Competition between photoionization and wakefield effects

    PubMed Central

    González de Alaiza Martínez, P.; Davoine, X.; Debayle, A.; Gremillet, L.; Bergé, L.

    2016-01-01

    We numerically investigate terahertz (THz) pulse generation by linearly-polarized, two-color femtosecond laser pulses in highly-ionized argon. Major processes consist of tunneling photoionization and ponderomotive forces associated with transverse and longitudinal field excitations. By means of two-dimensional particle-in-cell (PIC) simulations, we reveal the importance of photocurrent mechanisms besides transverse and longitudinal plasma waves for laser intensities >1015 W/cm2. We demonstrate the following. (i) With two-color pulses, photoionization prevails in the generation of GV/m THz fields up to 1017 W/cm2 laser intensities and suddenly loses efficiency near the relativistic threshold, as the outermost electron shell of ionized Ar atoms has been fully depleted. (ii) PIC results can be explained by a one-dimensional Maxwell-fluid model and its semi-analytical solutions, offering the first unified description of the main THz sources created in plasmas. (iii) The THz power emitted outside the plasma channel mostly originates from the transverse currents. PMID:27255689

  8. Terahertz radiation driven by two-color laser pulses at near-relativistic intensities: Competition between photoionization and wakefield effects.

    PubMed

    González de Alaiza Martínez, P; Davoine, X; Debayle, A; Gremillet, L; Bergé, L

    2016-06-03

    We numerically investigate terahertz (THz) pulse generation by linearly-polarized, two-color femtosecond laser pulses in highly-ionized argon. Major processes consist of tunneling photoionization and ponderomotive forces associated with transverse and longitudinal field excitations. By means of two-dimensional particle-in-cell (PIC) simulations, we reveal the importance of photocurrent mechanisms besides transverse and longitudinal plasma waves for laser intensities >10(15) W/cm(2). We demonstrate the following. (i) With two-color pulses, photoionization prevails in the generation of GV/m THz fields up to 10(17) W/cm(2) laser intensities and suddenly loses efficiency near the relativistic threshold, as the outermost electron shell of ionized Ar atoms has been fully depleted. (ii) PIC results can be explained by a one-dimensional Maxwell-fluid model and its semi-analytical solutions, offering the first unified description of the main THz sources created in plasmas. (iii) The THz power emitted outside the plasma channel mostly originates from the transverse currents.

  9. Ce(IV)- and light-driven water oxidation by [Ru(terpy)(pic)3]2+ analogues: catalytic and mechanistic studies.

    PubMed

    Duan, Lele; Xu, Yunhua; Tong, Lianpeng; Sun, Licheng

    2011-02-18

    A series of mononuclear ruthenium polypyridyl complexes [Ru(Mebimpy)(pic)(3)](PF(6))(2) (2; Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; pic = 4-picoline), Ru(bimpy)(pic)(3) (3; H(2)bimpy = 2,6-bis(benzimidazol-2-yl)pyridine), trans-[Ru(terpy)(pic)(2)Cl](PF(6)) (4; terpy = 2,2';6',2"-terpyridine), and trans-[Ru(terpy)(pic)(2)(OH(2))](ClO(4))(2) (5) are synthesized and characterized as analogues of the known Ru complex, [Ru(terpy)(pic)(3)](PF(6))(2) (1). The effect of the ligands on electronic and catalytic properties is studied and discussed. The negatively charged ligand, bimpy(2-), has a remarkable influence on the electrochemical events due to its strong electron-donating ability. The performance in light- and Ce(IV)-driven (Ce(IV) = Ce(NH(4))(2)(NO(3))(6)) water oxidation is successfully demonstrated. We propose that ligand exchange between pic and H(2)O occurs to form the real catalyst, a Ru-aqua complex. The synthesis and testing of trans-[Ru(terpy)(pic)(2)(OH(2))](ClO(4))(2) (5) confirmed our proposal. In addition, complex 5 possesses the best catalytic activity among these five complexes.

  10. PICs, TECs and LECs: Lessons to Be Learnt from the Differences between the USA Private Industry Councils and Britain's Training and Enterprise Councils.

    ERIC Educational Resources Information Center

    Bennett, Robert J.

    1994-01-01

    Comparison of Britain's Training and Enterprise Councils/Local Enterprise Companies with the United States' Private Industry Councils (PICs) shows common problems: inadequate financing, labor market fragmentation, staff turnover, and lack of national strategy. PICs have a clearer mission and greater success in developing partnerships with local…

  11. Axion string dynamics I: 2+1D

    NASA Astrophysics Data System (ADS)

    Fleury, Leesa M.; Moore, Guy D.

    2016-05-01

    If the axion exists and if the initial axion field value is uncorrelated at causally disconnected points, then it should be possible to predict the efficiency of cosmological axion production, relating the axionic dark matter density to the axion mass. The main obstacle to making this prediction is correctly treating the axion string cores. We develop a new algorithm for treating the axionic string cores correctly in 2+1 dimensions. When the axionic string cores are given their full physical string tension, axion production is about twice as efficient as in previous simulations. We argue that the string network in 2+1 dimensions should behave very differently than in 3+1 dimensions, so this result cannot be simply carried over to the physical case. We outline how to extend our method to 3+1D axion string dynamics.

  12. 1D-transport properties of single superconducting lead nanowires

    NASA Astrophysics Data System (ADS)

    Michotte, S.; Mátéfi-Tempfli, S.; Piraux, L.

    2003-09-01

    We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have uniform diameter of ∼40 nm and a very large aspect ratio (∼500). The diameter of the nanowire is small enough to ensure a 1D superconducting regime in a wide temperature range below Tc. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied DC current (or voltage). The current induced breakdowns in the V- I characteristics may be explained by the formation of phase slip centers. Moreover, DC voltage driven measurements reveal the existence of a new S-shape behavior near the formation of these phase slip centers.

  13. Microlens Masses from 1-D Parallaxes and Heliocentric Proper Motions

    NASA Astrophysics Data System (ADS)

    Gould, Andrew

    2014-12-01

    One-dimensional (1-D) microlens parallaxes can be combined with heliocentric lens-source relative proper motion measurements to derive the lens mass and distance, as suggested by Ghosh et al. (2004). Here I present the first mathematical anlysis of this procedure, which I show can be represented as a quadratic equation. Hence, it is formally subject to a two-fold degeneracy. I show that this degeneracy can be broken in many cases using the relatively crude 2-D parallax information that is often available for microlensing events. I also develop an explicit formula for the region of parameter space where it is more difficult to break this degeneracy. Although no mass/distance measurements have yet been made using this technique, it is likely to become quite common over the next decade.

  14. Quadratic Finite Element Method for 1D Deterministic Transport

    SciTech Connect

    Tolar, Jr., D R; Ferguson, J M

    2004-01-06

    In the discrete ordinates, or SN, numerical solution of the transport equation, both the spatial ({und r}) and angular ({und {Omega}}) dependences on the angular flux {psi}{und r},{und {Omega}}are modeled discretely. While significant effort has been devoted toward improving the spatial discretization of the angular flux, we focus on improving the angular discretization of {psi}{und r},{und {Omega}}. Specifically, we employ a Petrov-Galerkin quadratic finite element approximation for the differencing of the angular variable ({mu}) in developing the one-dimensional (1D) spherical geometry S{sub N} equations. We develop an algorithm that shows faster convergence with angular resolution than conventional S{sub N} algorithms.

  15. Effective theory of black holes in the 1/D expansion

    NASA Astrophysics Data System (ADS)

    Emparan, Roberto; Shiromizu, Tetsuya; Suzuki, Ryotaku; Tanabe, Kentaro; Tanaka, Takahiro

    2015-06-01

    The gravitational field of a black hole is strongly localized near its horizon when the number of dimensions D is very large. In this limit, we can effectively replace the black hole with a surface in a background geometry (e.g. Minkowski or Anti-deSitter space). The Einstein equations determine the effective equations that this `black hole surface' (or membrane) must satisfy. We obtain them up to next-to-leading order in 1/ D for static black holes of the Einstein-(A)dS theory. To leading order, and also to next order in Minkowski backgrounds, the equations of the effective theory are the same as soap-film equations, possibly up to a redshift factor. In particular, the Schwarzschild black hole is recovered as a spherical soap bubble. Less trivially, we find solutions for `black droplets', i.e. black holes localized at the boundary of AdS, and for non-uniform black strings.

  16. Connected components of irreducible maps and 1D quantum phases

    NASA Astrophysics Data System (ADS)

    Szehr, Oleg; Wolf, Michael M.

    2016-08-01

    We investigate elementary topological properties of sets of completely positive (CP) maps that arise in quantum Perron-Frobenius theory. We prove that the set of primitive CP maps of fixed Kraus rank is path-connected and we provide a complete classification of the connected components of irreducible CP maps at given Kraus rank and fixed peripheral spectrum in terms of a multiplicity index. These findings are then applied to analyse 1D quantum phases by studying equivalence classes of translational invariant matrix product states that correspond to the connected components of the respective CP maps. Our results extend the previously obtained picture in that they do not require blocking of physical sites, they lead to analytic paths, and they allow us to decompose into ergodic components and to study the breaking of translational symmetry.

  17. Glycolipid antigen processing for presentation by CD1d molecules.

    PubMed

    Prigozy, T I; Naidenko, O; Qasba, P; Elewaut, D; Brossay, L; Khurana, A; Natori, T; Koezuka, Y; Kulkarni, A; Kronenberg, M

    2001-01-26

    The requirement for processing glycolipid antigens in T cell recognition was examined with mouse CD1d-mediated responses to glycosphingolipids (GSLs). Although some disaccharide GSL antigens can be recognized without processing, the responses to three other antigens, including the disaccharide GSL Gal(alpha1-->2)GalCer (Gal, galactose; GalCer, galactosylceramide), required removal of the terminal sugars to permit interaction with the T cell receptor. A lysosomal enzyme, alpha-galactosidase A, was responsible for the processing of Gal(alpha1-->2)GalCer to generate the antigenic monosaccharide epitope. These data demonstrate a carbohydrate antigen processing system analogous to that used for peptides and an ability of T cells to recognize processed fragments of complex glycolipids.

  18. Generalized Ohm's law for relativistic plasmas

    NASA Astrophysics Data System (ADS)

    Kandus, A.; Tsagas, C. G.

    2008-04-01

    We generalize the relativistic expression of Ohm's law by studying a multifluid system of charged species using the 1 + 3 covariant formulation of general relativistic electrodynamics. This is done by providing a fully relativistic, fully non-linear propagation equation for the spatial component of the electric 4-current. Our analysis proceeds along the lines of the non-relativistic studies and extends previous relativistic work on cold plasmas. Exploiting the compactness and transparency of the covariant formalism, we provide a direct comparison with the standard Newtonian versions of Ohm's law and identify the relativistic corrections in an unambiguous way. The generalized expression of Ohm's law is initially given relative to an arbitrary observer and for a multicomponent relativistic charged medium. Then, the law is written with respect to the Eckart frame and for a hot two-fluid plasma with zero total charge. Finally, we apply our analysis to a cold proton-electron plasma and recover the well-known magnetohydrodynamic expressions. In every step, we discuss the approximations made and identify familiar effects, like the Biermann battery and the Hall effect.

  19. Relativistic effects in Lyman-α forest

    NASA Astrophysics Data System (ADS)

    Iršič, Vid; Di Dio, Enea; Viel, Matteo

    2016-02-01

    We present the calculation of the Lyman-alpha (Lyman-α) transmitted flux fluctuations with full relativistic corrections to the first order. Even though several studies exist on relativistic effects in galaxy clustering, this is the first study to extend the formalism to a different tracer of underlying matter at unique redshift range (z=2-5). Furthermore, we show a comprehensive application of our calculations to the Quasar-Lyman-α cross-correlation function. Our results indicate that the signal of relativistic effects are sizeable at Baryonic Acoustic Oscillation (BAO) scale mainly due to the large differences in density bias factors of our tracers. We construct an observable, the anti-symmetric part of the cross-correlation function, that is dominated by the relativistic signal and offers a new way to measure the relativistic terms at relatively small scales. The analysis shows that relativistic effects are important when considering cross-correlations between tracers with very different biases, and should be included in the data analysis of the current and future surveys. Moreover, the idea presented in this paper is highly complementary to other techniques and observables trying to isolate the effect of the relativistic corrections and thus test the validity of the theory of gravity beyond the Newtonian regime.

  20. Invisibility cloaks in relativistic motion

    NASA Astrophysics Data System (ADS)

    Halimeh, Jad C.; Thompson, Robert T.; Wegener, Martin

    2016-01-01

    We consider an ideal invisibility cloak which is illuminated by monochromatic light and which moves in vacuum at constant relativistic velocity with respect to the common inertial frame of light source and observer. We show that, in general, the moving cloak becomes detectable by image distortions and by generating a broad frequency spectrum of the scattered light. However, for many special combinations of incident light frequency, wave vector of light, and cloak velocity, ideal cloaking remains possible. It becomes nonreciprocal though. This means that light rays emitted by the light source arrive at the observer as though they have traveled through vacuum, but they take completely different paths after being retroreflected at the observer position.

  1. Particle distributions in collisionless magnetic reconnection: An implicit Particle-In-Cell (PIC) description

    SciTech Connect

    Hewett, D.W.; Francis, G.E.; Max, C.E.

    1990-06-29

    Evidence from magnetospheric and solar flare research supports the belief that collisionless magnetic reconnection can proceed on the Alfven-wave crossing timescale. Reconnection behavior that occurs this rapidly in collisionless plasmas is not well understood because underlying mechanisms depend on the details of the ion and electron distributions in the vicinity of the emerging X-points. We use the direct implicit Particle-In-Cell (PIC) code AVANTI to study the details of these distributions as they evolve in the self-consistent E and B fields of magnetic reconnection. We first consider a simple neutral sheet model. We observe rapid movement of the current-carrying electrons away from the emerging X-point. Later in time an oscillation of the trapped magnetic flux is found, superimposed upon continued linear growth due to plasma inflow at the ion sound speed. The addition of a current-aligned and a normal B field widen the scope of our studies.

  2. Study of negative hydrogen ion beam optics using the 3D3V PIC model

    SciTech Connect

    Miyamoto, K.; Nishioka, S.; Goto, I.; Hatayama, A.; Hanada, M.; Kojima, A.

    2015-04-08

    The mechanism of negative ion extraction under real conditions with the complex magnetic field is studied by using the 3D PIC simulation code. The extraction region of the negative ion source for the negative ion based neutral beam injection system in fusion reactors is modelled. It is shown that the E x B drift of electrons is caused by the magnetic filter and the electron suppression magnetic field, and the resultant asymmetry of the plasma meniscus. Furthermore, it is indicated that that the asymmetry of the plasma meniscus results in the asymmetry of negative ion beam profile including the beam halo. It could be demonstrated theoretically that the E x B drift is not significantly weakened by the elastic collisions of the electrons with neutral particles.

  3. Catalog of velocity distributions around a reconnection site in 2D PIC simulations

    NASA Astrophysics Data System (ADS)

    Lechner, Lukas; Bourdin, Philippe-A.; Nakamura, Takuma K. M.; Nakamura, Rumi; Narita, Yasuhito

    2016-04-01

    The velocity distribution of electrons and ions are known to be a marker for regions where magnetic reconnection develops. Past theoretical and computational works demonstrated that non-gyrotropic and anisotropic distributions depending on particle meandering motions and accelerations are seen around the reconnection point. The Magnetospheric Multiscale (MMS) mission is expected to resolve such kinetic scale reconnection regions. We present a catalog of velocity distribution functions that can give hints on the location within the current sheet relative to the reconnection point, which is sometimes unclear from pure spacecraft observations. We use 2D PIC simulations of anti-parallel magnetic reconnection to obtain velocity distributions at different locations, like in the center of the reconnection site, the ion and electron diffusion regions, or the reconnection inflow and outflow regions. With sufficiently large number of particles we resolve the distribution functions also in rather small regions. Such catalog may be compared with future MMS observations of the Earth's magnetotail.

  4. Multi-dimensional PIC-simulations of parametric instabilities for shock-ignition conditions

    NASA Astrophysics Data System (ADS)

    Riconda, C.; Weber, S.; Klimo, O.; Héron, A.; Tikhonchuk, V. T.

    2013-11-01

    Laser-plasma interaction is investigated for conditions relevant for the shock-ignition (SI) scheme of inertial confinement fusion using two-dimensional particle-in-cell (PIC) simulations of an intense laser beam propagating in a hot, large-scale, non-uniform plasma. The temporal evolution and interdependence of Raman- (SRS), and Brillouin- (SBS), side/backscattering as well as Two-Plasmon-Decay (TPD) are studied. TPD is developing in concomitance with SRS creating a broad spectrum of plasma waves near the quarter-critical density. They are rapidly saturated due to plasma cavitation within a few picoseconds. The hot electron spectrum created by SRS and TPD is relatively soft, limited to energies below one hundred keV.

  5. Particle-In-Cell (PIC) simulation of long-anode magnetron

    NASA Astrophysics Data System (ADS)

    Verma, Rajendra Kumar; Maurya, Shivendra; Singh, Vindhyavasini Prasad

    2016-03-01

    Long Anode Magnetron (LAM) is a design scheme adopted to attain greater thermal stability and higher power levels for the conventional magnetrons. So a LAM for 5MW Power level at 2.858 GHz was `Virtual Prototyped' using Admittance Matching field theory (AMT) andthen a PIC Study (Beam-wave interaction) was conducted using CST Particle Studio (CST-PS) which is explained in this paper. The convincing results thus obtained were - hot resonant frequency of 2.834 GHz. Output power of 5 MW at beam voltage of 58kV and applied magnetic field of 2200 Gauss with an overall efficiency of 45%. The simulated parameters values on comparison with the E2V LAM tube (M5028) were in good agreement which validates the feasibility of the design approach.

  6. PIC Simulations in Low Energy Part of PIP-II Proton Linac

    SciTech Connect

    Romanov, Gennady

    2014-07-01

    The front end of PIP-II linac is composed of a 30 keV ion source, low energy beam transport line (LEBT), 2.1 MeV radio frequency quadrupole (RFQ), and medium energy beam transport line (MEBT). This configuration is currently being assembled at Fermilab to support a complete systems test. The front end represents the primary technical risk with PIP-II, and so this step will validate the concept and demonstrate that the hardware can meet the specified requirements. SC accelerating cavities right after MEBT require high quality and well defined beam after RFQ to avoid excessive particle losses. In this paper we will present recent progress of beam dynamic study, using CST PIC simulation code, to investigate partial neutralization effect in LEBT, halo and tail formation in RFQ, total emittance growth and beam losses along low energy part of the linac.

  7. The Pic-du-Midi 2 meter telescope - First observations of the planets

    NASA Astrophysics Data System (ADS)

    Dollfus, A.

    1982-12-01

    The Pic-du-Midi Observatory is located at 2870 m altitude on the north slope of the Pyrenees. Instrumentation has been used at the site since 1941, due to clarity of the sky at that location. A 2 m telescope has recently been installed which is intended to gain a 0.1 arcsec resolution with an enlargement of 1500. The local stellar objects have been viewed with a resolution of 0.5 arcsec, while planetary surfaces have been observed at 0.15 arcsec resolution. Difficulties in maintaining an even temperature in the instrument because of the cold at the altitude and the strong winds are described. Sample observations of the galilean satellites of Jupiter, particularly Ganymede, in addition to Uranus, Saturn, and Mars are presented, with 1000 X enlargements of the latter.

  8. Relativistic electron beam driven longitudinal wake-wave breaking in a cold plasma

    NASA Astrophysics Data System (ADS)

    Bera, Ratan Kumar; Mukherjee, Arghya; Sengupta, Sudip; Das, Amita

    2016-08-01

    Space-time evolution of a relativistic electron beam driven wake-field in a cold, homogeneous plasma is studied using 1D-fluid simulation techniques. It is observed that the wake wave gradually evolves and eventually breaks, exhibiting sharp spikes in the density profile and sawtooth like features in the electric field profile [Bera et al., Phys. Plasmas 22, 073109 (2015)]. It is shown here that the excited wakefield is a longitudinal Akhiezer-Polovin mode [A. I. Akhiezer and R. V. Polovin, Sov. Phys. JETP 3, 696 (1956)] and its steepening (breaking) can be understood in terms of phase mixing of this mode, which arises because of relativistic mass variation effects. Further, the phase mixing time (breaking time) is studied as a function of beam density and beam velocity and is found to follow the well known scaling presented by Mukherjee and Sengupta [Phys. Plasmas 21, 112104 (2014)].

  9. Landau damping in relativistic plasmas

    NASA Astrophysics Data System (ADS)

    Young, Brent

    2016-02-01

    We examine the phenomenon of Landau damping in relativistic plasmas via a study of the relativistic Vlasov-Poisson (rVP) system on the torus for initial data sufficiently close to a spatially uniform steady state. We find that if the steady state is regular enough (essentially in a Gevrey class of degree in a specified range) and if the deviation of the initial data from this steady state is small enough in a certain norm, the evolution of the system is such that its spatial density approaches a uniform constant value quasi-exponentially fast (i.e., like exp ( - C |" separators=" t | ν ¯ ) for ν ¯ ∈ ( 0 , 1 ) ). We take as a priori assumptions that solutions launched by such initial data exist for all times (by no means guaranteed with rVP, but a reasonable assumption since we are close to a spatially uniform state) and that the various norms in question are continuous in time (which should be a consequence of an abstract version of the Cauchy-Kovalevskaya theorem). In addition, we must assume a kind of "reverse Poincaré inequality" on the Fourier transform of the solution. In spirit, this assumption amounts to the requirement that there exists 0 < ϰ < 1 so that the mass in the annulus ϰ ≤ |" separators=" v | < 1 for the solution launched by the initial data is uniformly small for all t. Typical velocity bounds for solutions to rVP launched by small initial data (at least on ℝ6) imply this bound. We note that none of our results require spherical symmetry (a crucial assumption for many current results on rVP).

  10. PIC Simulations of the Effect of Velocity Space Instabilities on Electron Viscosity and Thermal Conduction

    NASA Astrophysics Data System (ADS)

    Riquelme, Mario A.; Quataert, Eliot; Verscharen, Daniel

    2016-06-01

    In low-collisionality plasmas, velocity-space instabilities are a key mechanism providing an effective collisionality for the plasma. We use particle-in-cell (PIC) simulations to study the interplay between electron- and ion-scale velocity-space instabilities and their effect on electron pressure anisotropy, viscous heating, and thermal conduction. The adiabatic invariance of the magnetic moment in low-collisionality plasmas leads to pressure anisotropy, {{Δ }}{p}j\\equiv {p}\\perp ,j-{p}\\parallel ,j\\gt 0, if the magnetic field {\\boldsymbol{B}} is amplified ({p}\\perp ,j and {p}\\parallel ,j denote the pressure of species j (electron, ion) perpendicular and parallel to {\\boldsymbol{B}}). If the resulting anisotropy is large enough, it can in turn trigger small-scale plasma instabilities. Our PIC simulations explore the nonlinear regime of the mirror, IC, and electron whistler instabilities, through continuous amplification of the magnetic field | {\\boldsymbol{B}}| by an imposed shear in the plasma. In the regime 1≲ {β }j≲ 20 ({β }j\\equiv 8π {p}j/| {\\boldsymbol{B}}{| }2), the saturated electron pressure anisotropy, {{Δ }}{p}{{e}}/{p}\\parallel ,{{e}}, is determined mainly by the (electron-lengthscale) whistler marginal stability condition, with a modest factor of ˜1.5-2 decrease due to the trapping of electrons into ion-lengthscale mirrors. We explicitly calculate the mean free path of the electrons and ions along the mean magnetic field and provide a simple physical prescription for the mean free path and thermal conductivity in low-collisionality β j ≳ 1 plasmas. Our results imply that velocity-space instabilities likely decrease the thermal conductivity of plasma in the outer parts of massive, hot, galaxy clusters. We also discuss the implications of our results for electron heating and thermal conduction in low-collisionality accretion flows onto black holes, including Sgr A* in the Galactic Center.

  11. Nonstationary dynamics of the heliospheric termination shock in presence of pick up ions: PIC simulations

    NASA Astrophysics Data System (ADS)

    Yang, Zhongwei; Lembege, Bertrand; Lu, Quanming

    2014-05-01

    The nonstationary dynamic of the heliospheric termination shock in presence of pick up ions (PUI) is analyzed with the help of a one-dimensional PIC (particle-in-cell) simulation code. This work is initially stimulated by Voyager 2 data which evidenced the nonstationary behavior of the termination shock (TS) [Burlaga et al., 2008]. Recent hybrid and PIC simulation [Wu et al., 2010; Scholer and Matsukyio, 2011] have clarified the strong contribution of PUI in the global energy partition at the TS. Present work focusses on the nonstationary behavior of the shock front in presence of PUI (with different percentages) and its impact on the global energy partition (between protons and PUI) in the downstream region. Solar wind (SW) protons and PUI are described respectively as Maxwellian and a shell distributions. Present results (i) evidence that the TS front is still nonstationary (selfreformation of the shock front driven by the accumulation of SW ions) even in presence of 25% of PUI and even for a moderate supercritical Ma regime, (ii) confirm in average that 15% and 85% of the upstream SW energy is respectively transferred to protons and to PUI in the downstream region for a shock profile at a given time, (iii) analyzes the energy partition between reflected (R) and directly transmitted (DT) ions separately for SWI and PUI, and (iv) quantifies the impact of the nonstationarity of the shock front on local ion distribution. Moreover, present results show also quantitatively how the energy partition may vary between the SW protons and PUI in the heliosheath because of the front selfreformation. These results provide quantitative inputs on the strongly turbulent state (both in space and in time) of the heliosheath before it interacts with the heliopause.

  12. Cross-calibration of Landsat 5 TM and Landsat 8 OLI with Aqua MODIS using PICS

    NASA Astrophysics Data System (ADS)

    Angal, Amit; Mishra, Nischal; Xiong, Xiaoxiong; Helder, Dennis

    2014-09-01

    The Thematic Mapper (TM) onboard the Landsat 5 (L5) has provided an unprecedented amount of earth observations for more than 25 years since its launch on March 1, 1984. The MODIS sensor onboard the Aqua satellite is a part of the afternoon constellation of spacecraft and has been successfully providing near-continuous observations of the earth's surface and atmosphere since July 2002. A synergistic use of TM and MODIS reflective solar bands (RSB) measurements is immensely beneficial to the broad user community for different land cover change and global climate studies. A consistent radiometric calibration between the sensors is a prerequisite for creating high quality science products. Various pseudo-invariant calibration sites (PICS) identified by CEOS have been widely used to monitor the on-orbit calibration consistency for a number of sensors. Near-simultaneous observations of the Saharan PICS by L5 TM and Aqua MODIS are used in this study. The top-of-atmosphere (TOA) reflectance from the spectrally matching RSB are corrected for test site Bi-directional Reflectance Distribution Function (BRDF), relative spectral response (RSR) mismatch, and impacts for atmospheric water-vapor, and used to estimate the long-term calibration differences between the two sensors. The Operational Land Imager (OLI) onboard the Landsat 8 (L8) launched in February, 2013, is a follow-on mission to maintain the continuity of Landsat acquisitions. A similar cross-calibration methodology was extended to compare the spectrally matching bands of Aqua MODIS with OLI. A long-term drift is observed in bands 1 (3.7%) and 3 (1.86%) of L5 TM, which is expected to be mitigated in the next calibration coefficient update. With the exception of the SWIR-2 band (L5 TM band 7), the agreement with Aqua MODIS is seen to be within 4%. The L8 OLI and Aqua MODIS agreement is seen within 4% across all wavelengths.

  13. The 1994-1995 apparition of Mars observed from Pic-du-Midi

    NASA Astrophysics Data System (ADS)

    Erard, Stéphane

    2000-10-01

    The 1995 apparition of Mars was monitored with the Pic-du-Midi 1-m telescope from October 1994 to March 1995. Several thousand images were acquired with a CCD camera through various filters ranging from 0.4 to 1.05 μm. These images complete HST observations of the same apparition with a spatial resolution reduced by a factor of ˜4, but with a better time resolution. Low-resolution spectra were also acquired through a set of interferential filters at opposition, providing indications of mineralogical composition of surface materials. The only significant surface variations during the period are observed in the Cerberus area, which brightened at the end of winter. The whole apparition was very cloudy. The north Polar Hood dissipated in early December ( Ls˜25°). Migration of polar clouds to the equator is observed between January 31 and February 6 ( Ls˜50-55°). Then an Encircling Cloud Belt obscured most of the surface from February 22 to 24 at least ( Ls˜62°). The north polar cap regression is similar to that observed by Mariner 9, although several internal rifts developed during early spring, in particular the dark Lowell band and Rima Tenuis. A standstill is observed in the polar cap regression curve from Ls=55 to 70° at latitude ˜70°, at least in the 135-300° longitude range. The very strong spectral feature at 0.95 μm reported from HST observations of Olympia Planitia in July 1995 is not observed in the Pic-du-Midi images. The intermediate-dark region of Propontis I exhibits ferric absorption features consistent with high concentrations of crystalline hematite or other dark ferric materials.

  14. PIC-MCC/Fluid Hybrid Model for Low Pressure Capacitively Coupled O{sub 2} Plasma

    SciTech Connect

    Bera, Kallol; Rauf, Shahid; Collins, Ken

    2011-05-20

    Low pressure capacitively coupled plasmas are extensively used for advanced microelectronic device fabrication. Due to long electron mean free path and large bias voltages in this regime, kinetic effects play an important role in the dynamics of low pressure discharges. To take account of the kinetic effects, a one-dimensional hybrid plasma model has been developed that couples the Particle-In-Cell (PIC) technique for charged species and a fluid method for neutral species. The PIC model uses the Monte Carlo Collision (MCC) method to account for collision processes. The fluid model for neutral species takes into account species transport in the plasma, chemical reactions, and surface processes. An electronegative O{sub 2} plasma is simulated for a range of pressures (10-300 mTorr) and rf voltages (200-600 V) at 60 MHz. Our model for the O{sub 2} plasma considers electrons, O{sub 2}{sup +}, O{sup -}, O, and O*. The reaction mechanism includes electron impact dissociation, ionization, dissociative attachment and ion-ion recombination. Computational results are compared to our previous simulations for an electropositive Ar discharge. The electrons primarily absorb power from the external power supply at the sheath edge during sheath expansion. Energetic beam electrons are generated at the sheath edge during electron heating, which are responsible for plasma production and sustenance through collisions. The negative ions are found to be confined in the bulk plasma due to the potential well. The ratio of negative ions to electrons increases with increase in pressure and decrease in rf voltage. The spatial profiles of charged and neutral species in the plasma are found to primarily depend on species sources due to collisional processes.

  15. Ion acceleration in quasi-perpendicular PIC simulations of a reforming heliospheric termination shock

    NASA Astrophysics Data System (ADS)

    Lee, R. E.; Chapman, S. C.; Dendy, R. O.

    2003-12-01

    Recent Particle-in-cell (PIC) simulations have revealed time-dependent shock solutions for parameters relevant to astrophysical and heliospheric shocks [1,2,3]. These solutions are characterised by a shock which cyclically reforms on the spatio-temporal scales of the incoming protons. Whether a shock solution is stationary or reforming depends not only upon the correct treatment of the electrons, but also on the plasma parameters, the upstream β in particular. In the case of the heliospheric termination shock these parameters are not well determined, however, some estimates suggest that the termination shock may be in a parameter regime such that it is time-dependent. It has been pointed out [3] that this will switch off some acceleration mechanisms, for example shock surfing, which has been proposed previously for time-stationary shock solutions. The introduction of time-dependent electromagnetic fields intrinsic to the shock does however introduce the possibility of new mechanisms for the acceleration of protons. Here we present for the first time one such process as revealed by high phase space resolution 1.5D PIC simulations in which all vector quantities are three dimensional, the solution then varying with the spatial coordinate and time. We find that a subset of the protons that reflect off the reforming shock front are accelerated by subsequent interaction with the shock to form a suprathermal population which then propagates into the downstream region with energies of order six times the upstream inflow energy. These may provide an injection population for further acceleration to cosmic ray energies. [1] Shimada, N., and M. Hoshino, Astrophys. J, 543, L67, 2000. [2] Schmitz, H., S.C. Chapman and R.O. Dendy, Astrophys. J, 570, 637, 2002 [3] Scholer, M., I. Shinohara and S. Matsukiyo, J. Geophys. Res., 108, 1014, 2003

  16. Dual-band relativistic backward wave oscillators based on a single beam and dual beams

    NASA Astrophysics Data System (ADS)

    Ting, Wang; Jian-de, Zhang; Bao-liang, Qian; Xiao-ping, Zhang

    2010-04-01

    Two types of relativistic backward wave oscillators (RBWOs) used to produce dual-band microwaves are proposed and investigated by use of the particle-in-cell (PIC) simulation code KARAT [V. P. Tarakanov, User's Manual for Code Karat (Berkeley Research Associates, Springfield, VA, 1992)]. The first type of RBWO, for generation of C-band and X-band microwaves, is designed based on a single beam and a sectioned structure. With an electron beam of 650 keV and 5.0 kA guided by a magnetic field of 2.0 T, an average power of 380 MW with a total power conversion efficiency of 11.7% is obtained and the frequencies are 5.48 and 9.60 GHz, respectively. By changing the distance between the two sections, single-band oscillations are realized with higher power conversion efficiency than that of the dual-band oscillation. The second type, based on a coaxial structure and dual parallel annular beams, is a dual-band RBWO designed with separated beam-wave interaction regions for generation of C-band and X-band microwaves. With a dual beam of 650 keV and 11.8 kA (the outer beam current is 6.4 kA and inner beam current is 5.4 kA) guided by a magnetic field of 2.0 T, an output power of 1400 MW with a total power conversion efficiency of 18.3% is generated and the frequencies are 4.60 and 8.40 GHz, respectively. PIC simulations demonstrate that the two beam-wave interaction regions operate independently. The two types of dual-band RBWO are also compared and analyzed.

  17. Relativistic Theory of Few Body Systems

    SciTech Connect

    Franz Gross

    2002-11-01

    Very significant advances have been made in the relativistic theory of few body systems since I visited Peter Sauer and his group in Hannover in 1983. This talk provides an opportunity to review the progress in this field since then. Different methods for the relativistic calculation of few nucleon systems are briefly described. As an example, seven relativistic calculations of the deuteron elastic structure functions, A, B, and T{sub 20}, are compared. The covariant SPECTATOR {copyright} theory, among the more successful and complete of these methods, is described in more detail.

  18. STREAM INSTABILITIES IN RELATIVISTICALLY HOT PLASMA

    SciTech Connect

    Shaisultanov, Rashid; Lyubarsky, Yuri; Eichler, David

    2012-01-10

    The growth rates for Weibel and Buneman instabilities of relativistic ion beams in a relativistically hot electron background are derived analytically for general propagation angles. The Weibel instability perpendicular to the streaming direction is found to be the fastest growing mode and probably the first to appear. Oblique, quasiperpendicular modes grow almost as fast as the growth rate varies only moderately with angle, and they may distort or corrugate the filaments after the perpendicular mode saturates. The growth rate of the purely longitudinal (Buneman) mode is significantly smaller, contrary to the non-relativistic case. The results are consistent with simulations, which display aligned magnetic filaments and their subsequent disruption.

  19. Relativistic klystron research for linear colliders

    SciTech Connect

    Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Higo, T.; Hoag, H.A.; Koontz, R.F.

    1988-09-01

    Relativistic klystrons are being developed as a power source for high gradient accelerator applications which include large linear electron-positron colliders, compact accelerators, and FEL sources. We have attained 200 MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here on the design of our relativistic klystrons, the results of our experiments so far, and some of our plans for the near future. 5 refs., 9 figs., 1 tab.

  20. Language Development Component All Day Kindergarten--PIC Program 1991-92, Private Industry Council. Final Evaluation Report.

    ERIC Educational Resources Information Center

    Johnson, Jessie; Morgan, Kathy

    A study examined the effectiveness of the All Day Kindergarten-PIC Program instituted in the Columbus, Ohio Public Schools that provided full day instruction for underachieving kindergarten pupils. Implementation of the program was accomplished through daily instructional activities to strengthen and extend regular classroom instruction without…

  1. Resolution of choroidal neovascularization secondary to punctate inner choroidopathy (PIC) with intravitreal anti-VEGF agents: a case series.

    PubMed

    Mangat, Simran S; Ramasamy, B; Prasad, Som; Walters, Gavin; Mohammed, Moin; Mckibbin, Martin

    2011-01-01

    Case series of four patients with CNVM secondary to PIC treated solely with anti VEGF in three cases and in combination with PDT in the other. This series reveals long term follow up (3 months to 28 months) which is currently not described in the literature.

  2. 1.12 Tb/s superchannel coherent PM-QPSK InP transmitter photonic integrated circuit (PIC).

    PubMed

    Evans, P; Fisher, M; Malendevich, R; James, A; Goldfarb, G; Vallaitis, T; Kato, M; Samra, P; Corzine, S; Strzelecka, E; Studenkov, P; Salvatore, R; Sedgwick, F; Kuntz, M; Lal, V; Lambert, D; Dentai, A; Pavinski, D; Zhang, J; Cornelius, J; Tsai, T; Behnia, B; Bostak, J; Dominic, V; Nilsson, A; Taylor, B; Rahn, J; Sanders, S; Sun, H; Wu, K-T; Pleumeekers, J; Muthiah, R; Missey, M; Schneider, R; Stewart, J; Reffle, M; Butrie, T; Nagarajan, R; Ziari, M; Kish, F; Welch, D

    2011-12-12

    In this work, a 10-wavelength, polarization-multiplexed, monolithically integrated InP coherent QPSK transmitter PIC is demonstrated to operate at 112 Gb/sec per wavelength and total chip superchannel bandwidth of 1.12 Tb/s. This demonstration suggests that increasing data capacity to multi-Tb/s per chip is possible and likely in the future.

  3. External Validation of the Personality Inventory for Children (PIC) Profile and Factor Scales: Parent, Teacher, and Clinician Ratings.

    ERIC Educational Resources Information Center

    Lachar, David; And Others

    1984-01-01

    Attempted to expand the construct validity of the profile and factor scales for the Personality Inventory for Children (PIC) by determining the relationship of these scales to empirically derived dimensions of problem behaviors in children and adolescents (N=691). Results provided substantial evidence of convergent and discriminant validity. (LLL)

  4. Room-temperature fluorescence lifetime of pseudoisocyanine (PIC) J excitons with various aggregate morphologies in relation to microcavity polariton formation.

    PubMed

    Obara, Yuki; Saitoh, Keita; Oda, Masaru; Tani, Toshiro

    2012-01-01

    The results of room-temperature fluorescence lifetime measurements are reported for the excitation of J aggregates (Js) of pseudoisocyanine chloride (PIC-Cl) prepared in potassium polyvinyl sulfate (PVS) polymer thin films, their aqueous solutions, and NaCl aqueous solutions. Variations of the microscopic morphologies of the aggregates were investigated. The results show that fluorescence decay features correlated to the morphology change. The observed fluorescence lifetime and quantum efficiency of PIC J aggregates (PIC-Js) in a NaCl aqueous solution were 310 ps and 28%, respectively. The lifetime of the fibril-shaped macroaggregates prepared in PVS thin films was below the instrumental time resolution of 5 ps, and the efficiency decreased to below 3%. The results indicate that PIC-Js prepared with PVS polymers have an increased nonradiative contribution to the excitation deactivation process. In particular, macro-Js with isolated fibril-shaped structures revealed nonradiative pathway(s) that are closely associated to the specific packaging morphology of the constituent meso-Js. The possibility of a destructive effect on the formation of cavity-polaritons is also discussed.

  5. Two new species and new records of the genus Spinolyprops Pic, 1917 from the Oriental Region (Coleoptera, Tenebrionidae, Lupropini) (*).

    PubMed

    Schawaller, Wolfgang

    2012-01-01

    Two new species of the genus Spinolyprops Pic, 1917 (Tenebrionidae, subfamily Lagriinae Latreille, 1825) are described from Thailand and China (Spinolyprops cribricollissp. n., Spinolyprops thailandicussp. n.). The species characters within the genus are discussed, photographs of all seven Oriental species are added, a species key for the Oriental species is compiled, and a map with the distributional patterns is provided.

  6. What Do You See? The Supreme Court Decision in "PICS" and the Resegregation of Two Southern School Districts

    ERIC Educational Resources Information Center

    Anderson, Celia Rousseau

    2011-01-01

    Background/Context: In June 2007, the U.S. Supreme Court ruled to prohibit student assignment on the basis of race. In Parents Involved in Community Schools v. Seattle School District No. 1 (hereafter referred to as PICS), the court deemed race-based strategies used to voluntarily desegregate school districts to be unconstitutional. Although the…

  7. Relativistic quantum mechanics and relativistic entanglement in the rest-frame instant form of dynamics

    SciTech Connect

    Alba, David; Crater, Horace W.; Lusanna, Luca

    2011-06-15

    A new formulation of relativistic quantum mechanics is proposed in the framework of the rest-frame instant form of dynamics, where the world-lines of the particles are parametrized in terms of the Fokker-Pryce center of inertia and of Wigner-covariant relative 3-coordinates inside the instantaneous Wigner 3-spaces, and where there is a decoupled (non-covariant and non-local) canonical relativistic center of mass. This approach: (a) allows us to make a consistent quantization in every inertial frame; (b) leads to a description of both bound and scattering states; (c) offers new insights on the relativistic localization problem; (d) leads to a non-relativistic limit with a Hamilton-Jacobi treatment of the Newton center of mass; (e) clarifies non-local aspects (spatial non-separability) of relativistic entanglement connected with Lorentz signature and not present in its non-relativistic treatment.

  8. HEROIC: 3D general relativistic radiative post-processor with comptonization for black hole accretion discs

    NASA Astrophysics Data System (ADS)

    Narayan, Ramesh; Zhu, Yucong; Psaltis, Dimitrios; Saḑowski, Aleksander

    2016-03-01

    We describe Hybrid Evaluator for Radiative Objects Including Comptonization (HEROIC), an upgraded version of the relativistic radiative post-processor code HERO described in a previous paper, but which now Includes Comptonization. HEROIC models Comptonization via the Kompaneets equation, using a quadratic approximation for the source function in a short characteristics radiation solver. It employs a simple form of accelerated lambda iteration to handle regions of high scattering opacity. In addition to solving for the radiation field, HEROIC also solves for the gas temperature by applying the condition of radiative equilibrium. We present benchmarks and tests of the Comptonization module in HEROIC with simple 1D and 3D scattering problems. We also test the ability of the code to handle various relativistic effects using model atmospheres and accretion flows in a black hole space-time. We present two applications of HEROIC to general relativistic magnetohydrodynamics simulations of accretion discs. One application is to a thin accretion disc around a black hole. We find that the gas below the photosphere in the multidimensional HEROIC solution is nearly isothermal, quite different from previous solutions based on 1D plane parallel atmospheres. The second application is to a geometrically thick radiation-dominated accretion disc accreting at 11 times the Eddington rate. Here, the multidimensional HEROIC solution shows that, for observers who are on axis and look down the polar funnel, the isotropic equivalent luminosity could be more than 10 times the Eddington limit, even though the spectrum might still look thermal and show no signs of relativistic beaming.

  9. Activation of AMP-Activated Protein Kinase α and Extracelluar Signal-Regulated Kinase Mediates CB-PIC-Induced Apoptosis in Hypoxic SW620 Colorectal Cancer Cells.

    PubMed

    Cho, Sung-Yun; Lee, Hyo-Jeong; Lee, Hyo-Jung; Jung, Deok-Beom; Kim, Hyunseok; Sohn, Eun Jung; Kim, Bonglee; Jung, Ji Hoon; Kwon, Byoung-Mog; Kim, Sung-Hoon

    2013-01-01

    Here, antitumor mechanism of cinnamaldehyde derivative CB-PIC was elucidated in human SW620 colon cancer cells. CB-PIC significantly exerted cytotoxicity, increased sub-G1 accumulation, and cleaved PARP with apoptotic features, while it enhanced the phosphorylation of AMPK alpha and ACC as well as activated the ERK in hypoxic SW620 cells. Furthermore, CB-PIC suppressed the expression of HIF1 alpha, Akt, and mTOR and activated the AMPK phosphorylation in hypoxic SW620 cells. Conversely, silencing of AMPK α blocked PARP cleavage and ERK activation induced by CB-PIC, while ERK inhibitor PD 98059 attenuated the phosphorylation of AMPK α in hypoxic SW620 cells, implying cross-talk between ERK and AMPK α . Furthermore, cotreatment of CB-PIC and metformin enhanced the inhibition of HIF1 α and Akt/mTOR and the activation of AMPK α and pACC in hypoxic SW620 cells. In addition, CB-PIC suppressed the growth of SW620 cells inoculated in BALB/c athymic nude mice, and immunohistochemistry revealed that CB-PIC treatment attenuated the expression of Ki-67, CD34, and CAIX and increased the expression of pAMPK α in CB-PIC-treated group. Interestingly, CP-PIC showed better antitumor activity in SW620 colon cancer cells under hypoxia than under normoxia, since it may be applied to chemoresistance. Overall, our findings suggest that activation of AMPK α and ERK mediates CB-PIC-induced apoptosis in hypoxic SW620 colon cancer cells.

  10. Roles of TBC1D1 and TBC1D4 in insulin- and exercise-stimulated glucose transport of skeletal muscle

    PubMed Central

    Cartee, Gregory D.

    2014-01-01

    This review focuses on two paralogue Rab GTPase activating proteins known as TBC1D1 Tre-2/BUB2/cdc 1 domain family (TBC1D) 1 and TBC1D4 (also called Akt Substrate of 160 kDa, AS160) and their roles in controlling skeletal muscle glucose transport in response to the independent and combined effects of insulin and exercise. Convincing evidence implicates Akt2-dependent TBC1D4 phosphorylation on T642 as a key part of the mechanism for insulin-stimulated glucose uptake by skeletal muscle. TBC1D1 phosphorylation on several insulin-responsive sites (including T596, a site corresponding to T642 in TBC1D4) does not appear to be essential for in vivo insulin-stimulated glucose uptake by skeletal muscle. In vivo exercise or ex vivo contraction of muscle result in greater TBC1D1 phosphorylation on S237 that is likely to be secondary to increased AMP-activated protein kinase activity and potentially important for contraction-stimulated glucose uptake. Several studies that evaluated both normal and insulin-resistant skeletal muscle stimulated with a physiological insulin concentration after a single exercise session found that greater post-exercise insulin-stimulated glucose uptake was accompanied by greater TBC1D4 phosphorylation on several sites. In contrast, enhanced post-exercise insulin sensitivity was not accompanied by greater insulin-stimulated TBC1D1 phosphorylation. The mechanism for greater TBC1D4 phosphorylation in insulin-stimulated muscles after acute exercise is uncertain, and a causal link between enhanced TBC1D4 phosphorylation and increased post-exercise insulin sensitivity has yet to be established. In summary, TBC1D1 and TBC1D4 have important, but distinct roles in regulating muscle glucose transport in response to insulin and exercise. PMID:25280670

  11. Restoration of Akt activity by the bisperoxovanadium compound bpV(pic) attenuates hippocampal apoptosis in experimental neonatal pneumococcal meningitis.

    PubMed

    Sury, Matthias D; Vorlet-Fawer, Lorianne; Agarinis, Claudia; Yousefi, Shida; Grandgirard, Denis; Leib, Stephen L; Christen, Stephan

    2011-01-01

    Pneumococcal meningitis causes apoptosis of developing neurons in the dentate gyrus of the hippocampus. The death of these cells is accompanied with long-term learning and memory deficits in meningitis survivors. Here, we studied the role of the PI3K/Akt (protein kinase B) survival pathway in hippocampal apoptosis in a well-characterized infant rat model of pneumococcal meningitis. Meningitis was accompanied by a significant decrease of the PI3K product phosphatidylinositol 3,4,5-trisphosphate (PIP(3)) and of phosphorylated (i.e., activated) Akt in the hippocampus. At the cellular level, phosphorylated Akt was decreased in both the granular layer and the subgranular zone of the dentate gyrus, the region where the developing neurons undergo apoptosis. Protein levels and activity of PTEN, the major antagonist of PI3K, were unaltered by infection, suggesting that the observed decrease in PIP(3) and Akt phosphorylation is a result of decreased PI3K signaling. Treatment with the PTEN inhibitor bpV(pic) restored Akt activity and significantly attenuated hippocampal apoptosis. Co-treatment with the specific PI3K inhibitor LY294002 reversed the restoration of Akt activity and attenuation of hippocampal apoptosis, while it had no significant effect on these parameters on its own. These results indicate that the inhibitory effect of bpV(pic) on apoptosis was mediated by PI3K-dependent activation of Akt, strongly suggesting that bpV(pic) acted on PTEN. Treatment with bpV(pic) also partially inhibited the concentration of bacteria and cytokines in the CSF, but this effect was not reversed by LY294002, indicating that the effect of bpV(pic) on apoptosis was independent of its effect on CSF bacterial burden and cytokine levels. These results indicate that the PI3K/Akt pathway plays an important role in the death and survival of developing hippocampal neurons during the acute phase of pneumococcal meningitis.

  12. Theory of symmetry for a rotational relativistic Birkhoff system

    NASA Astrophysics Data System (ADS)

    Luo, Shao-Kai; Chen, Xiang-Wei; Guo, Yong-Xin

    2002-05-01

    The theory of symmetry for a rotational relativistic Birkhoff system is studied. In terms of the invariance of the rotational relativistic Pfaff-Birkhoff-D'Alembert principle under infinitesimal transformations, the Noether symmetries and conserved quantities of a rotational relativistic Birkhoff system are given. In terms of the invariance of rotational relativistic Birkhoff equations under infinitesimal transformations, the Lie symmetries and conserved quantities of the rotational relativistic Birkhoff system are given.

  13. Relativistic radiative transfer in relativistic plane-parallel flows: Behavior of the Eddington factor

    NASA Astrophysics Data System (ADS)

    Fukue, Jun

    2014-07-01

    Relativistic radiative transfer in a relativistic plane-parallel flow which is accelerated from its base, like an accretion disk wind, is numerically examined under a fully special-relativistic treatment. We first derive relativistic formal solutions. We then iteratively solve the relativistic transfer equation for several cases such as radiative equilibrium or local thermodynamic equilibrium, and obtain specific intensities in the inertial and comoving frames, as well as moment quantities and the Eddington factor. Moment quantities are rather different in each case, but the behavior of the Eddington factor for the plane-parallel case is quite similar in all cases. The Eddington factor generally depends on the flow velocity v as well as the optical depth τ. In the case of relativistic plane-parallel flows, in an optically thin regime of τ ≲ 1, it is slightly larger than 1/3 at very slow speed, it becomes smaller than 1/3 at mildly relativistic speed, and it again increases up to unity in the highly relativistic case. At highly relativistic speed, on the other hand, it becomes larger than 1/3 even in an optically thick regime. We find the Eddington approximation is fairly good, except for τ ≲ 1 or v/c ≳ 0.9, although the moment formalism under the Eddington approximation has some defects at v/c=1/√{3}.

  14. ULTRA-RELATIVISTIC NUCLEI: A NEW FRONTIER

    SciTech Connect

    MCLERRAN,L.

    1999-10-29

    The collisions of ultra-relativistic nuclei provide a window on the behavior of strong interactions at asymptotically high energies. They also will allow the authors to study the bulk properties of hadronic matter at very high densities.

  15. Relativistic perturbations for all the planets

    NASA Astrophysics Data System (ADS)

    Lestrade, J.-F.; Bretagnon, P.

    1982-01-01

    The relativistic perturbations in the osculating elements of all the planets, due to the theory of General Relativity, are presented where only the gravitational field of the sun is taken into account and the effects are calculated in the post-Newtonian approximation. The relativistic effects are calculated with the requirement that an accuracy of 5 x 10 to the -12th UA be kept over an interval of 1000 years, and are expressed in series form depending on the dynamical time in the isotropic coordinate and standard coordinate systems. The method uses equations derived from the equations of Gauss for the relativistic acceleration. A theory of the motion of Mercury is derived through the addition of the relativistic perturbations to the third-order Newtonian theory of Bretagnon (1981). It is noted that the computer programs used allow any values for the physical parameters Gamma and Beta of the Eddigton-Robertson metric.

  16. Relativistic Thomson Scatter from Factor Calculation

    2009-11-01

    The purpose of this program is calculate the fully relativistic Thomson scatter from factor in unmagnetized plasmas. Such calculations are compared to experimental diagnoses of plasmas at such facilities as the Jupiter laser facility here a LLNL.

  17. Pseudospectral approach to relativistic molecular theory.

    PubMed

    Nakajima, Takahito; Hirao, Kimihiko

    2004-08-22

    The efficient relativistic Dirac-Hartree-Fock (DHF) and Dirac-Kohn-Sham (DKS) methods are proposed by an application of the pseudospectral (PS) approach. The present PS-DHF/DKS method is a relativistic extension of the PS-HF/KS method of Friesner, though we aim at higher numerical accuracy by elimination of superfluous arbitrariness. The relativistic PS-DHF/DKS method is implemented into our REL4D programs. Several PS applications to molecular systems show that the relativistic PS-DHF/DKS approach is more efficient than the traditional approach without a loss of accuracy. The present PS-DKS method successfully assigns and predicts the photoelectron spectra of hexacarbonyl complexes of tungsten and seaborgium theoretically.

  18. Classical dynamics of the relativistic oscillator

    NASA Astrophysics Data System (ADS)

    Petrov, S. V.

    2016-11-01

    This paper aims at a comprehensive analysis of the dynamics of the classical relativistic oscillator. Numerical integration of its dynamical equations permits a thorough treatment of its motion. Both the one-dimensional and two-dimensional cases are considered.

  19. Relativistic quark-diquark model of baryons

    SciTech Connect

    Ferretti, J.; Vassallo, A.; Santopinto, E.

    2011-06-15

    A relativistic quark-diquark mass operator with direct and exchange interaction has been constructed in the framework of point form dynamics. The nonstrange baryon spectrum has been calculated and compared with experimental data.

  20. Quantum probability assignment limited by relativistic causality

    PubMed Central

    Han, Yeong Deok; Choi, Taeseung

    2016-01-01

    Quantum theory has nonlocal correlations, which bothered Einstein, but found to satisfy relativistic causality. Correlation for a shared quantum state manifests itself, in the standard quantum framework, by joint probability distributions that can be obtained by applying state reduction and probability assignment that is called Born rule. Quantum correlations, which show nonlocality when the shared state has an entanglement, can be changed if we apply different probability assignment rule. As a result, the amount of nonlocality in quantum correlation will be changed. The issue is whether the change of the rule of quantum probability assignment breaks relativistic causality. We have shown that Born rule on quantum measurement is derived by requiring relativistic causality condition. This shows how the relativistic causality limits the upper bound of quantum nonlocality through quantum probability assignment. PMID:26971717

  1. Quantum Deformations of Einstein's Relativistic Symmetries

    SciTech Connect

    Lukierski, Jerzy

    2006-11-03

    We shall outline two ways of introducing the modification of Einstein's relativistic symmetries of special relativity theory -- the Poincare symmetries. The most complete way of introducing the modifications is via the noncocommutative Hopf-algebraic structure describing quantum symmetries. Two types of quantum relativistic symmetries are described, one with constant commutator of quantum Minkowski space coordinates ({theta}{mu}{nu}-deformation) and second with Lie-algebraic structure of quantum space-time, introducing so-called {kappa}-deformation. The third fundamental constant of Nature - fundamental mass {kappa} or length {lambda} - appears naturally in proposed quantum relativistic symmetry scheme. The deformed Minkowski space is described as the representation space (Hopf-module) of deformed Poincare algebra. Some possible perspectives of quantum-deformed relativistic symmetries will be outlined.

  2. Relativistic projection and boost of solitons

    SciTech Connect

    Wilets, L.

    1991-01-01

    This report discusses the following topics on the relativistic projection and boost of solitons: The center of mass problem; momentum eigenstates; variation after projection; and the nucleon as a composite. (LSP).

  3. Relativistic projection and boost of solitons

    SciTech Connect

    Wilets, L.

    1991-12-31

    This report discusses the following topics on the relativistic projection and boost of solitons: The center of mass problem; momentum eigenstates; variation after projection; and the nucleon as a composite. (LSP).

  4. Coherent states for the relativistic harmonic oscillator

    NASA Technical Reports Server (NTRS)

    Aldaya, Victor; Guerrero, J.

    1995-01-01

    Recently we have obtained, on the basis of a group approach to quantization, a Bargmann-Fock-like realization of the Relativistic Harmonic Oscillator as well as a generalized Bargmann transform relating fock wave functions and a set of relativistic Hermite polynomials. Nevertheless, the relativistic creation and annihilation operators satisfy typical relativistic commutation relations of the Lie product (vector-z, vector-z(sup dagger)) approximately equals Energy (an SL(2,R) algebra). Here we find higher-order polarization operators on the SL(2,R) group, providing canonical creation and annihilation operators satisfying the Lie product (vector-a, vector-a(sup dagger)) = identity vector 1, the eigenstates of which are 'true' coherent states.

  5. Relativistic diffusive motion in random electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Haba, Z.

    2011-08-01

    We show that the relativistic dynamics in a Gaussian random electromagnetic field can be approximated by the relativistic diffusion of Schay and Dudley. Lorentz invariant dynamics in the proper time leads to the diffusion in the proper time. The dynamics in the laboratory time gives the diffusive transport equation corresponding to the Jüttner equilibrium at the inverse temperature β-1 = mc2. The diffusion constant is expressed by the field strength correlation function (Kubo's formula).

  6. Relativistic particle beams for interstellar propulsion

    NASA Astrophysics Data System (ADS)

    Nordley, Gerald D.

    1993-04-01

    The concept of pellet-stream propulsion proposed by Singer (1980) is extended to particle beams and relativistic velocities. A simple relativistic mission study is presented, and it is shown how certain technological developments might enhance the concept. In particular, considerations discussed include beam drivers; beam cooling, steering, and focusing; beam driven mission mechanics; and the radiation problem. The energy issues are also briefly considered.

  7. Mass versus relativistic and rest masses

    NASA Astrophysics Data System (ADS)

    Okun, L. B.

    2009-05-01

    The concept of relativistic mass, which increases with velocity, is not compatible with the standard language of relativity theory and impedes the understanding and learning of the theory by beginners. The same difficulty occurs with the term rest mass. To get rid of relativistic mass and rest mass it is appropriate to replace the equation E =mc2 by the true Einstein's equation E0=mc2, where E0 is the rest energy and m is the mass.

  8. On Lorentz invariants in relativistic magnetic reconnection

    NASA Astrophysics Data System (ADS)

    Yang, Shu-Di; Wang, Xiao-Gang

    2016-08-01

    Lorentz invariants whose nonrelativistic correspondences play important roles in magnetic reconnection are discussed in this paper. Particularly, the relativistic invariant of the magnetic reconnection rate is defined and investigated in a covariant two-fluid model. Certain Lorentz covariant representations for energy conversion and magnetic structures in reconnection processes are also investigated. Furthermore, relativistic measures for topological features of reconnection sites, particularly magnetic nulls and separatrices, are analyzed.

  9. Relativistic mean field description of exotic nuclei

    NASA Astrophysics Data System (ADS)

    Meng, Jie; Ring, Peter; Zhao, Pengwei; Zhou, Shan-Gui

    In this chapter, we will present relativistic mean field (RMF) models with pairing treated by the Bardeen-Cooper-Schrieffer (BCS) and the relativistic Hartree-Bogoliubov (RHB) approaches and applications for exotic nuclear phenomena including nuclear halos, the position of the proton drip line and proton radioactivity, the surface diffuseness and its relation to nuclear exotic phenomena, and the effects of pairing correlations on the nuclear size.

  10. Relativistic uranium beams - the Bevalac experience

    SciTech Connect

    Alonso, J.

    1983-03-01

    This paper will address areas where relativistic heavy ion accelerators differ from proton facilities. Salient areas are: (1) the specialized injectors for heavy ions; ion sources, structures for very low charge-to-mass ratio (q/A) ions, and stripper optimization; (2) special requirements for the synchrotron ring; ultrahigh vacuum, flexible controls and instrumentation. These areas are discussed in the context of the Bevalac, as well as our idea for a next-generation relativistic heavy ion accelerator.

  11. Relativistic klystron research at SLAC and LLNL

    SciTech Connect

    Allen, M.A.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Higo, T.; Hoag, H.A.; Lavine, T.L.; Lee, T.G.; Loew, G.A.; Miller, R.H.; Morton, P.L.; Palmer, R.B.; Paterson, J.M.; Ruth, R.D.; Schwarz, H.D.; Takeuchi, Y.; Vlieks, A.E.; Wang, J.W.; Wilson, P.B.; Hopkins, D.B.; Sessler, A.M.; Barletta, W.A.; Birx, D.L.; Boyd, J.K.; Houck, T.; Westenskow, G.A.; Yu, S.S.

    1988-06-01

    We are developing relativistic klystrons as a power source for high gradient accelerator applications such as large linear electron-positron colliders and compact accelerators. We have attained 200 MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here briefly on our experiments so far. 5 refs., 1 fig., 1 tab.

  12. Relativistically modulational instability by strong Langmuir waves

    SciTech Connect

    Liu, X. L.; Liu, S. Q.; Li, X. Q.

    2012-09-15

    Based on the set of nonlinear coupling equations, which has considered the relativistic effects of electrons, modulational instability by strong Langmuir waves has been investigated in this paper. Both the characteristic scale and maximum growth rate of the Langmuir field will enhance with the increase in the electron relativistic effect. The numerical results indicate that longitudinal perturbations induce greater instability than transverse perturbations do, which will lead to collapse and formation of the pancake-like structure.

  13. Relativistic particle acceleration in plerions

    NASA Technical Reports Server (NTRS)

    Arons, Jonathan; Tavani, Marco

    1994-01-01

    We discuss recent research on the structure and particle acceleration properties of relativistic shock waves in which the magnetic field is transverse to the flow direction in the upstream medium, and whose composition is either pure electrons and positrons or primarily electrons and positrons with an admixture of heavy ions. Particle-in-cell simulation techniques as well as analytic theory have been used to show that such shocks in pure pair plasmas are fully thermalized -- the downstream particle spectra are relativistic Maxwellians at the temperature expected from the jump conditions. On the other hand, shocks containing heavy ions which are a minority constituent by number but which carry most of the energy density in the upstream medium do put approximately 20% of the flow energy into a nonthermal population of pairs downstream, whose distribution in energy space is N(E) varies as E(exp -2), where N(E)dE is the number of particles with energy between E and E+dE. The mechanism of thermalization and particle acceleration is found to be synchrotron maser activity in the shock front, stimulated by the quasi-coherent gyration of the whole particle population as the plasma flowing into the shock reflects from the magnetic field in the shock front. The synchrotron maser modes radiated by the heavy ions are absorbed by the pairs at their (relativistic) cyclotron frequencies, allowing the maximum energy achievable by the pairs to be gamma(sub +/-)m(sub +/-)c squared = m(sub i)c squared gamma(sub 1)/Z(sub i), where gamma(sub 1) is the Lorentz factor of the upstream flow and Z(sub i) is the atomic number of the ions. The shock's spatial structure is shown to contain a series of 'overshoots' in the magnetic field, regions where the gyrating heavy ions compress the magnetic field to levels in excess of the eventual downstream value. This shock model is applied to an interpretation of the structure of the inner regions of the Crab Nebula, in particular to the 'wisps

  14. Relativistic positioning systems: Numerical simulations

    NASA Astrophysics Data System (ADS)

    Puchades Colmenero, Neus

    The position of users located on the Earth's surface or near it may be found with the classic positioning systems (CPS). Certain information broadcast by satellites of global navigation systems, as GPS and GALILEO, may be used for positioning. The CPS are based on the Newtonian formalism, although relativistic post-Newtonian corrections are done when they are necessary. This thesis contributes to the development of a different positioning approach, which is fully relativistic from the beginning. In the relativistic positioning systems (RPS), the space-time position of any user (ship, spacecraft, and so on) can be calculated with the help of four satellites, which broadcast their proper times by means of codified electromagnetic signals. In this thesis, we have simulated satellite 4-tuples of the GPS and GALILEO constellations. If a user receives the signals from four satellites simultaneously, the emission proper times read -after decoding- are the user "emission coordinates". In order to find the user "positioning coordinates", in an appropriate almost inertial reference system, there are two possibilities: (a) the explicit relation between positioning and emission coordinates (broadcast by the satellites) is analytically found or (b) numerical codes are designed to calculate the positioning coordinates from the emission ones. Method (a) is only viable in simple ideal cases, whereas (b) allows us to consider realistic situations. In this thesis, we have designed numerical codes with the essential aim of studying two appropriate RPS, which may be generalized. Sometimes, there are two real users placed in different positions, which receive the same proper times from the same satellites; then, we say that there is bifurcation, and additional data are needed to choose the real user position. In this thesis, bifurcation is studied in detail. We have analyzed in depth two RPS models; in both, it is considered that the satellites move in the Schwarzschild's space

  15. 1D X-ray Beam Compressing Monochromators

    SciTech Connect

    Korytar, D.; Dobrocka, E.; Konopka, P.; Zaprazny, Z.; Ferrari, C.; Mikulik, P.; Vagovic, P.; Ac, V.; Erko, A.; Abrosimov, N.

    2010-04-06

    A total beam compression of 5 and 10 corresponding to the asymmetry angles of 9 deg. and 12 deg. is achieved with V-5 and V-10 monochromators, respectively, in standard single crystal pure germanium (220) X-ray beam compressing (V-shaped) monochromators for CuKalpha{sub 1} radiation. A higher 1D compression of X-ray beam is possible using larger angles of asymmetry, however it is achieved at the expense of the total intensity, which is decreased due to the refraction effect. To increase the monochromator intensity, several ways are considered both theoretically and experimentally. Linearly graded germanium rich Ge{sub x}Si{sub (1-x)} single crystal was used to prepare a V-21 single crystal monochromator with 15 deg. asymmetry angles (compression factor of 21). Its temperature gradient version is discussed for CuKalpha{sub 1} radiation. X-ray diffraction measurements on the graded GeSi monochromator showed more than 3-times higher intensity at the output compared with that of a pure Ge monochromator.

  16. 1-D Numerical Analysis of RBCC Engine Performance

    NASA Technical Reports Server (NTRS)

    Han, Samuel S.

    1998-01-01

    An RBCC engine combines air breathing and rocket engines into a single engine to increase the specific impulse over an entire flight trajectory. Considerable research pertaining to RBCC propulsion was performed during the 1960's and these engines were revisited recently as a candidate propulsion system for either a single-stage-to-orbit (SSTO) or two-stage-to-orbit (TSTO) launch vehicle. There are a variety of RBCC configurations that had been evaluated and new designs are currently under development. However, the basic configuration of all RBCC systems is built around the ejector scramjet engine originally developed for the hypersonic airplane. In this configuration, a rocket engine plays as an ejector in the air-augmented initial acceleration mode, as a fuel injector in scramjet mode and the rocket in all rocket mode for orbital insertion. Computational fluid dynamics (CFD) is a useful tool for the analysis of complex transport processes in various components in RBCC propulsion systems. The objective of the present research was to develop a transient 1-D numerical model that could be used to predict flow behavior throughout a generic RBCC engine following a flight path.

  17. Dynamic decoupling in the presence of 1D random walk

    NASA Astrophysics Data System (ADS)

    Chakrabarti, Arnab; Chakraborty, Ipsita; Bhattacharyya, Rangeet

    2016-05-01

    In the recent past, many dynamic decoupling sequences have been proposed for the suppression of decoherence of spins connected to thermal baths of various natures. Dynamic decoupling schemes for suppressing decoherence due to Gaussian diffusion have also been developed. In this work, we study the relative performances of dynamic decoupling schemes in the presence of a non-stationary Gaussian noise such as a 1D random walk. Frequency domain analysis is not suitable to determine the performances of various dynamic decoupling schemes in suppressing decoherence due to such a process. Thus, in this work, we follow a time domain calculation to arrive at the following conclusions: in the presence of such a noise, we show that (i) the traditional Carr–Purcell–Meiboom–Gill (CPMG) sequence outperforms Uhrig’s dynamic decoupling scheme, (ii) CPMG remains the optimal sequence for suppression of decoherence due to random walk in the presence of an external field gradient. Later, the theoretical predictions are experimentally verified by using nuclear magnetic resonance spectroscopy on spin 1/2 particles diffusing in a liquid medium.

  18. Control and imaging of O(1D2) precession

    NASA Astrophysics Data System (ADS)

    Wu, Shiou-Min; Radenovic, Dragana Č.; van der Zande, Wim J.; Groenenboom, Gerrit C.; Parker, David H.; Vallance, Claire; Zare, Richard N.

    2011-01-01

    Larmor precession of a quantum mechanical angular momentum vector about an applied magnetic field forms the basis for a range of magnetic resonance techniques, including nuclear magnetic resonance spectroscopy and magnetic resonance imaging. We have used a polarized laser pump-probe scheme with velocity-map imaging detection to visualize, for the first time, the precessional motion of a quantum mechanical angular momentum vector. Photodissociation of O2 at 157 nm provides a clean source of fast-moving O(1D2) atoms, with their electronic angular momentum vector strongly aligned perpendicular to the recoil direction. In the presence of an external magnetic field, the distribution of atomic angular momenta precesses about the field direction, and polarization-sensitive images of the atomic scattering distribution recorded as a function of field strength yield ‘time-lapse-photography’ style movies of the precessional motion. We present movies recorded in various experimental geometries, and discuss potential consequences and applications in atmospheric chemistry and reaction dynamics.

  19. Absolute rate constant determinations for the deactivation of O/1D/ by time resolved decay of O/1D/ yields O/3P/ emission

    NASA Technical Reports Server (NTRS)

    Davidson, J. A.; Sadowski, C. M.; Schiff, H. I.; Howard, C. J.; Schmeltekopf, A. L.; Jennings, D. A.; Streit, G. E.

    1976-01-01

    Absolute rate constants for the deactivation of O(1D) atoms by some atmospheric gases have been determined by observing the time-resolved emission of O(1D) at 630 nm. O(1D) atoms were produced by the dissociation of ozone via repetitive laser pulses at 266 nm. Absolute rate constants for the relaxation of O(1D) at 298 K are reported for N2, O2, CO2, O3, H2, D2, CH4, HCl, NH3, H2O, N2O, and Ne. The results obtained are compared with previous relative and absolute measurements reported in the literature.

  20. RELATIVISTIC HEAVY ION COLLISIONS: EXPERIMENT

    SciTech Connect

    Friedlander, Erwin M.; Heckman, Harry H.

    1982-04-01

    Relativistic heavy ion physics began as a 'no man's land' between particle and nuclear physics, with both sides frowning upon it as 'unclean', because on one hand, hadronic interactions and particle production cloud nuclear structure effects, while on the other, the baryonic environment complicates the interpretation of production experiments. They have attempted to review here the experimental evidence on RHI collisions from the point of view that it represents a new endeavor in the understanding of strong interaction physics. Such an approach appears increasingly justified; first, by the accumulation of data and observations of new features of hadronic interactions that could not have been detected outside a baryonic environment; second, by the maturation of the field owing to the advances made over the past several years in experimental inquiries on particle production by RHI, including pions, kaons, hyperons, and searches for antiprotons; and third, by the steady and progressive increase in the energy and mass ranges of light nuclear beams that have become available to the experiment; indeed the energy range has widened from the {approx} 0.2 to 2 AGeV at the Bevalac to {approx}4 AGeV at Dubna and recently, to the quantum jump in energies to {approx} 1000 equivalent AGeV at the CERN PS-ISR. Accompanying these expansions in the energy frontier are the immediate prospects for very heavy ion beams at the Bevalac up to, and including, 1 AGeV {sup 238}U, thereby extending the 'mass frontier' to its ultimate extent.

  1. The Relativistic Heavy Ion Collider

    NASA Astrophysics Data System (ADS)

    Fischer, Wolfram

    The Relativistic Heavy Ion Collider (RHIC), shown in Fig. 1, was build to study the interactions of quarks and gluons at high energies [Harrison, Ludlam and Ozaki (2003)]. The theory of Quantum Chromodynamics (QCD) describes these interactions. One of the main goals for the RHIC experiments was the creation and study of the Quark-Gluon Plasma (QGP), which was expected to be formed after the collision of heavy ions at a temperature of approximately 2 trillion kelvin (or equivalently an energy of 150 MeV). The QGP is the substance which existed only a few microseconds after the Big Bang. The QGP was anticipated to be weakly interacting like a gas but turned out to be strongly interacting and more like a liquid. Among its unusual properties is its extremely low viscosity [Auerbach and Schlomo (2009)], which makes the QGP the substance closest to a perfect liquid known to date. The QGP is opaque to moderate energy quarks and gluons leading to a phenomenon called jet quenching, where of a jet and its recoil jet only one is observable and the other suppressed after traversing and interacting with the QGP [Jacak and Müller (2012)]...

  2. Observation of relativistic antihydrogen atoms

    SciTech Connect

    Blanford, Glenn DelFosse

    1998-01-01

    An observation of relativistic antihydrogen atoms is reported in this dissertation. Experiment 862 at Fermi National Accelerator Laboratory observed antihydrogen atoms produced by the interaction of a circulating beam of high momentum (3 < p < 9 GeV/c) antiprotons and a jet of molecular hydrogen gas. Since the neutral antihydrogen does not bend in the antiproton source magnets, the detectors could be located far from the interaction point on a beamline tangent to the storage ring. The detection of the antihydrogen is accomplished by ionizing the atoms far from the interaction point. The positron is deflected by a magnetic spectrometer and detected, as are the back to back photons resulting from its annihilation. The antiproton travels a distance long enough for its momentum and time of flight to be measured accurately. A statistically significant sample of 101 antihydrogen atoms has been observed. A measurement of the cross section for {bar H}{sup 0} production is outlined within. The cross section corresponds to the process where a high momentum antiproton causes e{sup +} e{sup -} pair creation near a nucleus with the e{sup +} being captured by the antiproton. Antihydrogen is the first atom made exclusively of antimatter to be detected. The observation experiment's results are the first step towards an antihydrogen spectroscopy experiment which would measure the n = 2 Lamb shift and fine structure.

  3. Observation of relativistic antihydrogen atoms

    SciTech Connect

    Blanford, G.D.

    1997-12-31

    An observation of relativistic antihydrogen atoms is reported in this dissertation. Experiment 862 at Fermi National Accelerator Laboratory observed antihydrogen atoms produced by the interaction of a circulating beam of high momentum (3 < p < 9 GeV/c) antiprotons and a jet of molecular hydrogen gas. Since the neutral antihydrogen does not bend in the antiproton source magnets, the detectors could be located far from the interaction point on a beamline tangent to the storage ring. The detection of the antihydrogen is accomplished by ionizing the atoms far from the interaction point. The positron is deflected by a magnetic spectrometer and detected, as are the back to back photons resulting from its annihilation. The antiproton travels a distance long enough for its momentum and time of flight to be measured accurately. A statistically significant sample of 101 antihydrogen atoms has been observed. A measurement of the cross section for {anti H}{sup 0} production is outlined within. The cross section corresponds to the process where a high momentum antiproton causes e{sup +}e{sup {minus}} pair creation near a nucleus with the e{sup +} being captured by the antiproton. Antihydrogen is the first atom made exclusively of antimatter to be detected. The observation experiment`s results are the first step towards an antihydrogen spectroscopy experiment which would measure the n = 2 Lamb shift and fine structure.

  4. Observation of relativistic antihydrogen atoms

    NASA Astrophysics Data System (ADS)

    Blanford, Glenn Delfosse, Jr.

    1997-09-01

    An observation of relativistic antihydrogen atoms is reported in this dissertation. Experiment 862 at Fermi National Accelerator Laboratory observed antihydrogen atoms produced by the interaction of a circulating beam of high momentum (3 < p < 9 GeV/c) antiprotons and a jet of molecular hydrogen gas. Since the neutral antihydrogen does not bend in the antiproton source magnets, the detectors could be located far from the interaction point on a beamline tangent to the storage ring. The detection of the antihydrogen is accomplished by ionizing the atoms far from the interaction point. The positron is deflected by a magnetic spectrometer and detected, as are the back to back photons resulting from its annihilation. The antiproton travels a distance long enough for its momentum and time of flight to be measured accurately. A statistically significant sample of 101 antihydrogen atoms has been observed. A measurement of the cross section for /bar Ho production is outlined within. The cross section corresponds to the process where a high momentum antiproton causes e+e/sp- pair creation near a nucleus with the e+ being captured by the antiproton. Antihydrogen is the first atom made exclusively of antimatter to be detected. The observation experiment's results are the first step towards an antihydrogen spectroscopy experiment which would measure the n = 2 Lamb shift and fine structure.

  5. Detonation waves in relativistic hydrodynamics

    SciTech Connect

    Cissoko, M. )

    1992-02-15

    This paper is concerned with an algebraic study of the equations of detonation waves in relativistic hydrodynamics taking into account the pressure and the energy of thermal radiation. A new approach to shock and detonation wavefronts is outlined. The fluid under consideration is assumed to be perfect (nonviscous and nonconducting) and to obey the following equation of state: {ital p}=({gamma}{minus}1){rho} where {ital p}, {rho}, and {gamma} are the pressure, the total energy density, and the adiabatic index, respectively. The solutions of the equations of detonation waves are reduced to the problem of finding physically acceptable roots of a quadratic polynomial {Pi}({ital X}) where {ital X} is the ratio {tau}/{tau}{sub 0} of dynamical volumes behind and ahead of the detonation wave. The existence and the locations of zeros of this polynomial allow it to be shown that if the equation of state of the burnt fluid is known then the variables characterizing the unburnt fluid obey well-defined physical relations.

  6. Relativistic Dipole Matrix Element Zeros

    NASA Astrophysics Data System (ADS)

    Lajohn, L. A.; Pratt, R. H.

    2002-05-01

    There is a special class of relativistic high energy dipole matrix element zeros (RZ), whose positions with respect to photon energy ω , only depend on the bound state l quantum number according to ω^0=mc^2/(l_b+1) (independent of primary quantum number n, nuclear charge Z, central potential V and dipole retardation). These RZ only occur in (n,l_b,j_b)arrow (ɛ , l_b+1,j_b) transitions such as ns_1/2arrow ɛ p_1/2; np_3/2arrow ɛ d_3/2: nd_5/2arrow ɛ f_5/2 etc. The nonrelativistic limit of these matrix elements can be established explicitly in the Coulomb case. Within the general matrix element formalism (such as that in [1]); when |κ | is substituted for γ in analytic expressions for matrix elements, the zeros remain, but ω^0 now becomes dependent on n and Z. When the reduction to nonrelativistic form is completed by application of the low energy approximation ω mc^2 mc^2, the zeros disappear. This nonzero behavior was noted in nonrelativistic dipole Coulomb matrix elements by Fano and Cooper [2] and later proven by Oh and Pratt[3]. (J. H. Scofield, Phys. Rev. A 40), 3054 (1989 (U. Fano and J. W. Cooper, Rev. Mod. Phys. 40), 441 (1968). (D. Oh and R. H. Pratt, Phys. Rev. A 34), 2486 (1986); 37, 1524 (1988); 45, 1583 (1992).

  7. Evidence against dopamine D1/D2 receptor heteromers

    PubMed Central

    Frederick, Aliya L.; Yano, Hideaki; Trifilieff, Pierre; Vishwasrao, Harshad D.; Biezonski, Dominik; Mészáros, József; Sibley, David R.; Kellendonk, Christoph; Sonntag, Kai C.; Graham, Devon L.; Colbran, Roger J.; Stanwood, Gregg D.; Javitch, Jonathan A.

    2014-01-01

    Hetero-oligomers of G-protein-coupled receptors have become the subject of intense investigation because their purported potential to manifest signaling and pharmacological properties that differ from the component receptors makes them highly attractive for the development of more selective pharmacological treatments. In particular, dopamine D1 and D2 receptors have been proposed to form hetero-oligomers that couple to Gαq proteins, and SKF83959 has been proposed to act as a biased agonist that selectively engages these receptor complexes to activate Gαq and thus phospholipase C. D1/D2 heteromers have been proposed as relevant to the pathophysiology and treatment of depression and schizophrenia. We used in vitro bioluminescence resonance energy transfer (BRET), ex vivo analyses of receptor localization and proximity in brain slices, and behavioral assays in mice to characterize signaling from these putative dimers/oligomers. We were unable to detect Gαq or Gα11 protein coupling to homomers or heteromers of D1 or D2 receptors using a variety of biosensors. SKF83959-induced locomotor and grooming behaviors were eliminated in D1 receptor knockout mice, verifying a key role for D1-like receptor activation. In contrast, SKF83959-induced motor responses were intact in D2 receptor and Gαq knockout mice, as well as in knock-in mice expressing a mutant Ala286-CaMKIIα, that cannot autophosphorylate to become active. Moreover, we found that in the shell of the nucleus accumbens, even in neurons in which D1 and D2 receptor promoters are both active, the receptor proteins are segregated and do not form complexes. These data are not compatible with SKF83959 signaling through Gαq or through a D1–D2 heteromer and challenge the existence of such a signaling complex in the adult animals that we used for our studies. PMID:25560761

  8. Dynamical functions of a 1D correlated quantum liquid

    NASA Astrophysics Data System (ADS)

    Carmelo, J. M. P.; Bozi, D.; Penc, K.

    2008-10-01

    The dynamical correlation functions in one-dimensional electronic systems show power-law behaviour at low energies and momenta close to integer multiples of the charge and spin Fermi momenta. These systems are usually referred to as Tomonaga-Luttinger liquids. However, near well defined lines of the (k,ω) plane the power-law behaviour extends beyond the low-energy cases mentioned above, and also appears at higher energies, leading to singular features in the photoemission spectra and other dynamical correlation functions. The general spectral-function expressions derived in this paper were used in recent theoretical studies of the finite-energy singular features in photoemission of the organic compound tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) metallic phase. They are based on a so-called pseudofermion dynamical theory (PDT), which allows us to systematically enumerate and describe the excitations in the Hubbard model starting from the Bethe ansatz, as well as to calculate the charge and spin object phase shifts appearing as exponents of the power laws. In particular, we concentrate on the spin-density m\\rightarrow 0 limit and on effects in the vicinity of the singular border lines, as well as close to half filling. Our studies take into account spectral contributions from types of microscopic processes that do not occur for finite values of the spin density. In addition, the specific processes involved in the spectral features of TTF-TCNQ are studied. Our results are useful for the further understanding of the unusual spectral properties observed in low-dimensional organic metals and also provide expressions for the one- and two-atom spectral functions of a correlated quantum system of ultracold fermionic atoms in a 1D optical lattice with on-site two-atom repulsion.

  9. Synthesis, characterization, and physical properties of 1D nanostructures

    NASA Astrophysics Data System (ADS)

    Marley, Peter Mchael

    The roster of materials exhibiting metal---insulator transitions with sharply discontinuous switching of electrical conductivity close to room temperature remains rather sparse despite the fundamental interest in the electronic instabilities manifested in such materials and the plethora of potential technological applications, ranging from frequency-agile metamaterials to electrochromic coatings and Mott field-effect transistors. Vanadium oxide bronzes with the general formula MxV2O 5, provide a wealth of compositions and frameworks where strong electron correlation can be systematically (albeit thus far only empirically) tuned. Charge fluctuations along the quasi-1D frameworks of MxV 2O5 bronzes have evinced much recent interest owing to the manifestation of colossal metal---insulator transitions and superconductivity. We start with a general review on the phase transitions, both electronic and structural, of vanadium oxide bronzes in Chapter 1. In Chapter 2, we demonstrate an unprecedented reversible transformation between double-layered (delta) and tunnel (beta) quasi-1D geometries for nanowires of a divalent vanadium bronze CaxV2O5 (x ˜0.23) upon annealing-induced dehydration and hydrothermally-induced hydration. Such a facile hydration/dehydration-induced interconversion between two prominent quasi-1D structures (accompanied by a change in charge ordering motifs) has not been observed in the bulk and is posited to result from the ease of propagation of crystallographic slip processes across the confined nanowire widths for the delta→beta conversion and the facile diffusion of water molecules within the tunnel geometries for the beta→delta reversion. We demonstrate in Chapter 3 unprecedented pronounced metal-insulator transitions induced by application of a voltage for nanowires of a vanadium oxide bronze with intercalated divalent cations, beta-PbxV 2O5 (x ˜0.33). The induction of the phase transition through application of an electric field at room

  10. Synthesis, characterization, and physical properties of 1D nanostructures

    NASA Astrophysics Data System (ADS)

    Marley, Peter Mchael

    The roster of materials exhibiting metal---insulator transitions with sharply discontinuous switching of electrical conductivity close to room temperature remains rather sparse despite the fundamental interest in the electronic instabilities manifested in such materials and the plethora of potential technological applications, ranging from frequency-agile metamaterials to electrochromic coatings and Mott field-effect transistors. Vanadium oxide bronzes with the general formula MxV2O 5, provide a wealth of compositions and frameworks where strong electron correlation can be systematically (albeit thus far only empirically) tuned. Charge fluctuations along the quasi-1D frameworks of MxV 2O5 bronzes have evinced much recent interest owing to the manifestation of colossal metal---insulator transitions and superconductivity. We start with a general review on the phase transitions, both electronic and structural, of vanadium oxide bronzes in Chapter 1. In Chapter 2, we demonstrate an unprecedented reversible transformation between double-layered (delta) and tunnel (beta) quasi-1D geometries for nanowires of a divalent vanadium bronze CaxV2O5 (x ˜0.23) upon annealing-induced dehydration and hydrothermally-induced hydration. Such a facile hydration/dehydration-induced interconversion between two prominent quasi-1D structures (accompanied by a change in charge ordering motifs) has not been observed in the bulk and is posited to result from the ease of propagation of crystallographic slip processes across the confined nanowire widths for the delta→beta conversion and the facile diffusion of water molecules within the tunnel geometries for the beta→delta reversion. We demonstrate in Chapter 3 unprecedented pronounced metal-insulator transitions induced by application of a voltage for nanowires of a vanadium oxide bronze with intercalated divalent cations, beta-PbxV 2O5 (x ˜0.33). The induction of the phase transition through application of an electric field at room

  11. SCCRO3 (DCUN1D3) Antagonizes the Neddylation and Oncogenic Activity of SCCRO (DCUN1D1)*

    PubMed Central

    Huang, Guochang; Stock, Cameron; Bommeljé, Claire C.; Weeda, Víola B.; Shah, Kushyup; Bains, Sarina; Buss, Elizabeth; Shaha, Manish; Rechler, Willi; Ramanathan, Suresh Y.; Singh, Bhuvanesh

    2014-01-01

    The activity of cullin-RING type ubiquitination E3 ligases is regulated by neddylation, a process analogous to ubiquitination that culminates in covalent attachment of the ubiquitin-like protein Nedd8 to cullins. As a component of the E3 for neddylation, SCCRO/DCUN1D1 plays a key regulatory role in neddylation and, consequently, cullin-RING ligase activity. The essential contribution of SCCRO to neddylation is to promote nuclear translocation of the cullin-ROC1 complex. The presence of a myristoyl sequence in SCCRO3, one of four SCCRO paralogues present in humans that localizes to the membrane, raises questions about its function in neddylation. We found that although SCCRO3 binds to CAND1, cullins, and ROC1, it does not efficiently bind to Ubc12, promote cullin neddylation, or conform to the reaction processivity paradigms, suggesting that SCCRO3 does not have E3 activity. Expression of SCCRO3 inhibits SCCRO-promoted neddylation by sequestering cullins to the membrane, thereby blocking its nuclear translocation. Moreover, SCCRO3 inhibits SCCRO transforming activity. The inhibitory effects of SCCRO3 on SCCRO-promoted neddylation and transformation require both an intact myristoyl sequence and PONY domain, confirming that membrane localization and binding to cullins are required for in vivo functions. Taken together, our findings suggest that SCCRO3 functions as a tumor suppressor by antagonizing the neddylation activity of SCCRO. PMID:25349211

  12. Birkhoff's equations and geometrical theory of rotational relativistic system

    NASA Astrophysics Data System (ADS)

    Luo, Shao-kai; Chen, Xiang-wei; Fu, Jing-li

    2001-04-01

    The Birkhoffian and Birkhoff's functions of a rotational relativistic system are constructed, the Pfaff action of rotational relativistic system is defined, the Pfaff-Birkhoff principle of a rotational relativistic system is given and the Pfaff-Birkhoff-D'Alembert principles and Birkhoff's equations of rotational relativistic system are constructed. The geometrical description of a rotational relativistic system is studied and the exact properties of Birkhoff's equations and their forms on R×T*M for a rotational relativistic system are obtained. The global analysis of Birkhoff's equations for a rotational relativistic system is studied, the global properties of autonomous, semi-autonomous and non-autonomous rotational relativistic Birkhoff's equations and the geometrical properties of energy change for rotational relativistic Birkhoff's equations are given.

  13. PIC Simulations of mini-magnetospheres above the lunar surface and the formation of Lunar Swirls

    NASA Astrophysics Data System (ADS)

    Bamford, R. A.; Alves, E. P.; Kellett, B.; Bradford, W. J.; Silva, L.; Crawford, I. A.; Trines, R. M. G. M.; Fonseca, R. A.; Gargate, L.; Bingham, R.

    2013-09-01

    the shock altitude). In this small scale regime below the ion gyro radius (which is generally ›› 100km), the plasma has to be treated by kinetic theory and a particle-in-a-cell (PIC) code is necessary to model the complex dynamics taking place between the solar wind and the crustal magnetic fields. We will describe results of PIC simulations and compare them to in-situ observations from multiple lunar missions as well as laboratory experiments.

  14. 3D Relativistic MHD Simulations of Magnetized Spine-Sheath Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Mizuno, Yosuke; Hardee, Philip E.; Nishikawa, Ken-Ichi

    2007-01-01

    We have performed numerical simulations of weakly and strongly magnetized relativistic jets embedded in a weakly and strongly magnetized stationary or mildly relativistic (0.5c) sheath using the RAISHIN code. In the numerical simulations a jet with Lorentz factor gamma=2.5 is precessed to break the initial equilibrium configuration. Results of the numerical simulations are compared to theoretical predictions from a normal mode-analysis of the linearized RMHD equations describing a uniform axially magnetized cylindrical relativistic jet embedded in a uniform axially magnetized moving sheath. The prediction of increased stability of a weakly-magnetized system with mildly relativistic sheath flow to Kelvin-Helmholtz instabilities and the stabilization of a strongly-magnetized system with mildly relativistic sheath flow is confirmed by the numerical simulations.

  15. A 3+1 dimensional viscous hydrodynamic code for relativistic heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Karpenko, Iu.; Huovinen, P.; Bleicher, M.

    2014-11-01

    We describe the details of 3+1 dimensional relativistic hydrodynamic code for the simulations of quark-gluon/hadron matter expansion in ultra-relativistic heavy ion collisions. The code solves the equations of relativistic viscous hydrodynamics in the Israel-Stewart framework. With the help of ideal-viscous splitting, we keep the ability to solve the equations of ideal hydrodynamics in the limit of zero viscosities using a Godunov-type algorithm. Milne coordinates are used to treat the predominant expansion in longitudinal (beam) direction effectively. The results are successfully tested against known analytical relativistic inviscid and viscous solutions, as well as against existing 2+1D relativistic viscous code. Catalogue identifier: AETZ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AETZ_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 13 825 No. of bytes in distributed program, including test data, etc.: 92 750 Distribution format: tar.gz Programming language: C++. Computer: any with a C++ compiler and the CERN ROOT libraries. Operating system: tested on GNU/Linux Ubuntu 12.04 x64 (gcc 4.6.3), GNU/Linux Ubuntu 13.10 (gcc 4.8.2), Red Hat Linux 6 (gcc 4.4.7). RAM: scales with the number of cells in hydrodynamic grid; 1900 Mbytes for 3D 160×160×100 grid. Classification: 1.5, 4.3, 12. External routines: CERN ROOT (http://root.cern.ch), Gnuplot (http://www.gnuplot.info/) for plotting the results. Nature of problem: relativistic hydrodynamical description of the 3-dimensional quark-gluon/hadron matter expansion in ultra-relativistic heavy ion collisions. Solution method: finite volume Godunov-type method. Running time: scales with the number of hydrodynamic cells; typical running times on Intel(R) Core(TM) i7-3770 CPU @ 3.40 GHz, single thread mode, 160

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

    NASA Astrophysics Data System (ADS)

    Lidia, Steven Michael

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

  17. 1-D Tremor Streaks: Implications for a Streak Source Model

    NASA Astrophysics Data System (ADS)

    Houston, H.; Ghosh, A.; Vidale, J. E.

    2009-12-01

    Recent observations of non-volcanic tremor in Cascadia and Japan show “streaks” of tremor moving up and down dip in a convergence-parallel direction at “driving velocities” (i.e., 30 to 120 km/hr). Streak lengths of 30 to 40 km are occasionally observed. We explore the implications of these observations for a source model and spectrum of tremor. Key elements involve the extreme geometry and slow “rupture velocity” implied by the streaks. The source spectrum of tremor and other ETS seismic radiation exhibits a spectral falloff roughly as the inverse of frequency (1/f) in contrast to that of earthquakes, which follow a spectral falloff of 1/f squared above a corner frequency. Nevertheless, several observations suggest that the deformation that generates tremor is shear slip in the plate convergence direction. A fundamental question, then, has been what slip source could produce such an observed 1/f falloff over a wide frequency range. We propose a kinematic model, consistent with the 1-D geometry of the tremor streaks, in which fault displacement and width are strongly limited and rupture growth occurs only along fault length, which is oriented in a convergence-parallel direction (up or down dip). This is a version of the well-known Haskell model in which the durations of the two boxcars are very different. A 1/f spectral falloff holds between the corner frequencies associated with the two durations. Thus, the frequency range of the observed 1/f spectral falloff of tremor provides constraints on the durations of the boxcars. Further constraints involve the maximum likely displacement in an ETS event, the rupture velocities of the streaks, and the moment release rate. The narrow streak geometry implies fairly high strain and stress drops, in contrast to the low overall stress drops inferred from tidal modulation of tremor and the low strain across the entire ETS region. The observation of tremor streaks migrating at 10's of km/hour, in conjunction with the

  18. Human CD1d knock-in mouse model demonstrates potent antitumor potential of human CD1d-restricted invariant natural killer T cells

    PubMed Central

    Wen, Xiangshu; Rao, Ping; Carreño, Leandro J.; Kim, Seil; Lawrenczyk, Agnieszka; Porcelli, Steven A.; Cresswell, Peter; Yuan, Weiming

    2013-01-01

    Despite a high degree of conservation, subtle but important differences exist between the CD1d antigen presentation pathways of humans and mice. These differences may account for the minimal success of natural killer T (NKT) cell-based antitumor therapies in human clinical trials, which contrast strongly with the powerful antitumor effects in conventional mouse models. To develop an accurate model for in vivo human CD1d (hCD1d) antigen presentation, we have generated a hCD1d knock-in (hCD1d-KI) mouse. In these mice, hCD1d is expressed in a native tissue distribution pattern and supports NKT cell development. Reduced numbers of invariant NKT (iNKT) cells were observed, but at an abundance comparable to that in most normal humans. These iNKT cells predominantly expressed mouse Vβ8, the homolog of human Vβ11, and phenotypically resembled human iNKT cells in their reduced expression of CD4. Importantly, iNKT cells in hCD1d knock-in mice exert a potent antitumor function in a melanoma challenge model. Our results show that replacement of mCD1d by hCD1d can select a population of functional iNKT cells closely resembling human iNKT cells. These hCD1d knock-in mice will allow more accurate in vivo modeling of human iNKT cell responses and will facilitate the preclinical assessment of iNKT cell-targeted antitumor therapies. PMID:23382238

  19. Amplification of Weibel instability in the relativistic beam-plasma interactions due to ion streaming

    NASA Astrophysics Data System (ADS)

    Ardaneh, Kazem; Cai, DongSheng; Nishikawa, Ken-Ichi

    2014-11-01

    On the basis of a three-dimensional relativistic electromagnetic particle-in-cell (PIC) code, we have analyzed the Weibel instability driven by a relativistic electron-ion beam propagating into an unmagnetized ambient electron-ion plasma. The analysis is focused on the ion contribution in the instability, considering the earliest evolution in shock formation. Simulation results demonstrate that the Weibel instability is responsible for generating and amplifying the small-scale, fluctuating, and dominantly transversal magnetic fields. These magnetic fields deflect particles behind the beam front both perpendicular and parallel to the beam propagation direction. Initially, the incoming electrons respond to field fluctuations growing as the result of the Weibel instability. Therefore, the electron current filaments are generated and the total magnetic energy grows linearly due to the mutual attraction between the filaments, and downstream advection of the magnetic field perturbations. When the magnetic fields become strong enough to deflect the much heavier ions, the ions begin to get involved in the instability. Subsequently, the linear growth of total magnetic energy decreases because of opposite electron-ion currents and topological change in the structure of magnetic fields. The ion current filaments are then merged and magnetic field energy grows more slowly at the expense of the energy stored in ion stream. It has been clearly illustrated that the ion current filaments extend through a larger scale in the longitudinal direction, while extension of the electron filaments is limited. Hence, the ions form current filaments that are the sources of deeply penetrating magnetic fields. The results also reveal that the Weibel instability is further amplified due to the ions streaming, but on a longer time scale. Our simulation predictions are in valid agreement with those reported in the literature.

  20. Hybrid-PIC Modeling of the Transport of Atomic Boron in a Hall Thruster

    NASA Technical Reports Server (NTRS)

    Smith, Brandon D.; Boyd, Iaian D.; Kamhawi, Hani

    2015-01-01

    Computational analysis of the transport of boron eroded from the walls of a Hall thruster is performed by implementing sputter yields of hexagonal boron nitride and velocity distribution functions of boron within the hybrid-PIC model HPHall. The model is applied to simulate NASA's HiVHAc Hall thruster at a discharge voltage of 500V and discharge powers of 1-3 kW. The number densities of ground- and 4P-state boron are computed. The density of ground-state boron is shown to be a factor of about 30 less than the plasma density. The density of the excited state is shown to be about three orders of magnitude less than that of the ground state, indicating that electron impact excitation does not significantly affect the density of ground-state boron in the discharge channel or near-field plume of a Hall thruster. Comparing the rates of excitation and ionization suggests that ionization has a greater influence on the density of ground-state boron, but is still negligible. The ground-state boron density is then integrated and compared to cavity ring-down spectroscopy (CRDS) measurements for each operating point. The simulation results show good agreement with the measurements for all operating points and provide evidence in support of CRDS as a tool for measuring Hall thruster erosion in situ.