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Sample records for interactive stereo electron

  1. Interactive stereo electron microscopy enhanced with virtual reality

    Energy Technology Data Exchange (ETDEWEB)

    Bethel, E.Wes; Bastacky, S.Jacob; Schwartz, Kenneth S.

    2001-12-17

    An analytical system is presented that is used to take measurements of objects perceived in stereo image pairs obtained from a scanning electron microscope (SEM). Our system operates by presenting a single stereo view that contains stereo image data obtained from the SEM, along with geometric representations of two types of virtual measurement instruments, a ''protractor'' and a ''caliper''. The measurements obtained from this system are an integral part of a medical study evaluating surfactant, a liquid coating the inner surface of the lung which makes possible the process of breathing. Measurements of the curvature and contact angle of submicron diameter droplets of a fluorocarbon deposited on the surface of airways are performed in order to determine surface tension of the air/liquid interface. This approach has been extended to a microscopic level from the techniques of traditional surface science by measuring submicrometer rather than millimeter diameter droplets, as well as the lengths and curvature of cilia responsible for movement of the surfactant, the airway's protective liquid blanket. An earlier implementation of this approach for taking angle measurements from objects perceived in stereo image pairs using a virtual protractor is extended in this paper to include distance measurements and to use a unified view model. The system is built around a unified view model that is derived from microscope-specific parameters, such as focal length, visible area and magnification. The unified view model ensures that the underlying view models and resultant binocular parallax cues are consistent between synthetic and acquired imagery. When the view models are consistent, it is possible to take measurements of features that are not constrained to lie within the projection plane. The system is first calibrated using non-clinical data of known size and resolution. Using the SEM, stereo image pairs of grids and spheres of

  2. Electronics for the STEREO experiment

    CERN Document Server

    Hélaine, V

    2016-01-01

    The STEREO experiment, aiming to probe short baseline neutrino oscillations by precisely measuring reactor anti-neutrino spectrum, is currently under installation. It is located at short distance from the compact research reactor core of the Institut Laue-Langevin, Grenoble, France. Dedicated electronics, hosted in a single $\\mu$TCA crate, were designed for this experiment. In this article, the electronics requirements, architecture and the performances achieved are described. It is shown how intrinsic Pulse Shape Discrimination properties of the liquid scintillator are preserved and how custom adaptable logic is used to improve the muon veto efficiency.

  3. Interaction of algorithm and implementation for analog VLSI stereo vision

    Science.gov (United States)

    Hakkarainen, J. M.; Little, James J.; Lee, Hae-Seung; Wyatt, John L., Jr.

    1991-07-01

    Design of a high-speed stereo vision system in analog VLSI technology is reported. The goal is to determine how the advantages of analog VLSI--small area, high speed, and low power-- can be exploited, and how the effects of its principal disadvantages--limited accuracy, inflexibility, and lack of storage capacity--can be minimized. Three stereo algorithms are considered, and a simulation study is presented to examine details of the interaction between algorithm and analog VLSI implementation. The Marr-Poggio-Drumheller algorithm is shown to be best suited for analog VLSI implementation. A CCD/CMOS stereo system implementation is proposed, capable of operation at 6000 image frame pairs per second for 48 X 48 images, and faster than frame rate operation on 256 X 256 binocular image pairs.

  4. Trigger and readout electronics for the STEREO experiment

    CERN Document Server

    Bourrion, O; Bouvier, J; Vescovi, C; Bosson, G; Helaine, V; Lamblin, J; Li, C; Montanet, F; Real, J S; Salagnac, T; Ponchant, N; Stutz, A; Tourres, D; Zsoldos, S

    2015-01-01

    The STEREO experiment will search for a sterile neutrino by measuring the anti-neutrino energy spectrum as a function of the distance from the source, the ILL nuclear reactor. A dedicated electronic, hosted in a single microTCA crate, was designed for this experiment. It performs triggering in two stages with various selectable conditions, processing and readout via UDP/IPBUS on 68 photomultiplier signals continuously digitized at 250 MSPS. Additionally, for detector performance monitoring, the electronics allow on-line calibration by driving LED synchronously with the data acquisition. This paper describes the electronics requirements, architecture and the performances achieved.

  5. The Stereo Electron Spikes and the Interplanetary Magnetic Field

    Science.gov (United States)

    Jokipii, J. R.; Sheeley, N. R., Jr.; Wang, Y. M.; Giacalone, J.

    2016-12-01

    A recent paper (Klassen etal, 2015) discussed observations of a spike event of 55-65 keV electrons which occurred very nearly simultaneously at STEREO A and STEREO B, which at the time were separated in longitude by 38 degrees. The authors associated the spikes with a flare at the Sun near the footpoint of the nominal Archimedean spiral magnetic field line passing through STEREO A. The spike at STEREO A was delayed by 2.2 minutes from that at STEREOB. We discuss the observations in terms of a model in which the electrons, accelerated at the flare, propagate without significant scattering along magnetic field lines which separate or diverge as a function of radial distance from the Sun. The near simultaneity of the spikes at the two spacecraft is a natural consequence of this model. We interpret the divergence of the magnetic field lines as a consequence of field-line random walk and flux-tube expansion. We show that the field-line random walk in the absence of flux-tube expansion produces an rms spread of field lines significantly less than that which is required to produce to observed divergence. We find that observations of the solar wind and its source region at the time of the event can account for the observations in terms of propagation along interplanetary magnetic field-lines. Klassen, A., Dresing, N., Gomez-Herrero, R, and Heber, B., A&A 580, A115 (2015) Financial support for NS and YMW was provided by NASA and CNR.

  6. StereoPasting: interactive composition in stereoscopic images.

    Science.gov (United States)

    Tong, Ruo-Feng; Zhang, Yun; Cheng, Ke-Li

    2013-08-01

    We propose "StereoPasting," an efficient method for depth-consistent stereoscopic composition, in which a source 2D image is interactively blended into a target stereoscopic image. As we paint "disparity" on a 2D image, the disparity map of the selected region is gradually produced by edge-aware diffusion, and then blended with that of the target stereoscopic image. By considering constraints of the expected disparities and perspective scaling, the 2D object is warped to generate an image pair, which is then blended into the target image pair to get the composition result. The warping is formulated as an energy minimization, which could be solved in real time. We also present an interactive composition system, in which users can edit the disparity maps of 2D images by strokes, while viewing the composition results instantly. Experiments show that our method is intuitive and efficient for interactive stereoscopic composition. A lot of applications demonstrate the versatility of our method.

  7. Interacting Electrons

    Science.gov (United States)

    Martin, Richard M.; Reining, Lucia; Ceperley, David M.

    2016-06-01

    Preface; Part I. Interacting Electrons: Beyond the Independent-Particle Picture: 1. The many electron problem: introduction; 2. Signatures of electron correlation; 3. Concepts and models for interacting electrons; Part II. Foundations of Theory for Many-Body Systems: 4. Mean fields and auxiliary systems; 5. Correlation functions; 6. Many-body wavefunctions; 7. Particles and quasi-particles; 8. Functionals in many-particle physics; Part III. Many-Body Green's Function Methods: 9. Many-body perturbation theory: expansion in the interaction; 10. Many-body perturbation theory via functional derivatives; 11. The RPA and the GW approximation for the self-energy; 12. GWA calculations in practice; 13. GWA calculations: illustrative results; 14. RPA and beyond: the Bethe-Salpeter equation; 15. Beyond the GW approximation; 16. Dynamical mean field theory; 17. Beyond the single-site approximation in DMFT; 18. Solvers for embedded systems; 19. Characteristic hamiltonians for solids with d and f states; 20. Examples of calculations for solids with d and f states; 21. Combining Green's functions approaches: an outlook; Part IV. Stochastic Methods: 22. Introduction to stochastic methods; 23. Variational Monte Carlo; 24. Projector quantum Monte Carlo; 25. Path integral Monte Carlo; 26. Concluding remarks; Part V. Appendices: A. Second quantization; B. Pictures; C. Green's functions: general properties; D. Matsubara formulation for Green's functions for T ̸= 0; E. Time-ordering, contours, and non-equilibrium; F. Hedin's equations in a basis; G. Unique solutions in Green's function theory; H. Properties of functionals; I. Auxiliary systems and constrained search; J. Derivation of the Luttinger theorem; K. Gutzwiller and Hubbard approaches; References; Index.

  8. Observations of surface waves interacting with ice using stereo imaging

    Science.gov (United States)

    Campbell, Alexander J.; Bechle, Adam J.; Wu, Chin H.

    2014-06-01

    A powerful Automated Trinocular Stereo Imaging System (ATSIS) is used to remotely measure waves interacting with three distinct ice types: brash, frazil, and pancake. ATSIS is improved with a phase-only correlation matching algorithm and parallel computation to provide high spatial and temporal resolution 3-D profiles of the water/ice surface, from which the wavelength, frequency, and energy flux are calculated. Alongshore spatial frequency distributions show that pancake and frazil ices differentially attenuate at a greater rate for higher-frequency waves, causing a decrease in mean frequency. In contrast, wave propagation through brash ice causes a rapid increase in the dominant wave frequency, which may be caused by nonlinear energy transfer to higher frequencies due to collisions between the brash ice particles. Consistent to the results in frequency, the wavelengths in pancake and frazil ices increase but decrease in brash ice. The total wave energy fluxes decrease exponentially in both pancake and frazil ice, whereas the overall energy flux remain constant in the brash ice due to thin layer thickness. The spatial energy flux distributions also reveal that wave reflection occurs at the boundary of each ice layer, with reflection coefficient decaying exponentially away from the ice interface. Reflection is the strongest at the pancake/ice-free and frazil/brash interfaces and the weakest at the brash/ice-free interface. These high resolution observations measured by ATSIS demonstrate the spatially variable nature of waves propagating through ice.

  9. Automatic 3D reconstruction of quasi-planar stereo Scanning Electron Microscopy (SEM) images.

    Science.gov (United States)

    Roy, S; Meunier, J; Marian, A M; Vidal, F; Brunette, I; Costantino, S

    2012-01-01

    Scanning Electron Microscopy (SEM) is widely used in science to characterize the surface roughness of materials. Three-dimensional information can be obtained with SEM based on stereovision techniques. A stereo pair is typically obtained by tilting the sample by a few degrees. In this paper we present a fully automated method for 3D reconstruction from a SEM stereo pair without any particular constraint. Results are presented for corneal stromal surfaces.

  10. STEREO measurements of electron acceleration beyond fast Fermi at the bow shock

    CERN Document Server

    Pulupa, Marc; Opitz, Andrea; Fedorov, Andrei; Lin, Robert P; Sauvaud, Jean-Andre

    2012-01-01

    Solar wind electrons are accelerated and reflected upstream by the terrestrial bow shock into a region known as the electron foreshock. Previously observed electron spectra at low energies are consistent with a fast Fermi mechanism, based on the adiabatic conservation of the magnetic moment ({\\mu}) of the accelerated electrons. At higher energies, suprathermal power law tails are observed beyond the level predicted by fast Fermi. The SWEA and STE electron detectors on STEREO enable measurements of foreshock electrons with good energy resolution and sensitivity over the entire foreshock beam. We investigate the electron acceleration mechanism by comparing observed STEREO electron spectra with predictions based on a Liouville mapping of upstream electrons through a shock encounter. The foreshock electron beam extends up to several tens of keV, energies for which the Larmor radii of electrons is tens of km or greater. These radii are comparable to the scale sizes of the shock, and {\\mu} conservation no longer ap...

  11. Advanced scanning transmission stereo electron microscopy of structural and functional engineering materials

    Energy Technology Data Exchange (ETDEWEB)

    Agudo Jacome, L., E-mail: leonardo.agudo@bam.de [Institut fuer Werkstoffe, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Eggeler, G., E-mail: gunther.eggeler@ruhr-uni-bochum.de [Institut fuer Werkstoffe, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Dlouhy, A., E-mail: dlouhy@ipm.cz [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 616 62 Brno (Czech Republic)

    2012-11-15

    Stereo transmission electron microscopy (TEM) provides a 3D impression of the microstructure in a thin TEM foil. It allows to perform depth and TEM foil thickness measurements and to decide whether a microstructural feature lies inside of a thin foil or on its surface. It allows appreciating the true three-dimensional nature of dislocation configurations. In the present study we first review some basic elements of classical stereo TEM. We then show how the method can be extended by working in the scanning transmission electron microscope (STEM) mode of a modern analytical 200 kV TEM equipped with a field emission gun (FEG TEM) and a high angle annular dark field (HAADF) detector. We combine two micrographs of a stereo pair into one anaglyph. When viewed with special colored glasses the anaglyph provides a direct and realistic 3D impression of the microstructure. Three examples are provided which demonstrate the potential of this extended stereo TEM technique: a single crystal Ni-base superalloy, a 9% Chromium tempered martensite ferritic steel and a NiTi shape memory alloy. We consider the effect of camera length, show how foil thicknesses can be measured, and discuss the depth of focus and surface effects. -- Highlights: Black-Right-Pointing-Pointer The advanced STEM/HAADF diffraction contrast is extended to 3D stereo-imaging. Black-Right-Pointing-Pointer The advantages of the new technique over stereo-imaging in CTEM are demonstrated. Black-Right-Pointing-Pointer The new method allows foil thickness measurements in a broad range of conditions. Black-Right-Pointing-Pointer We show that features associated with ion milling surface damage can be beneficial for appreciating 3D features of the microstructure.

  12. Investigation on traceability of 3D Scanning Electron Microscopy based on the Stereo Pair Technique

    DEFF Research Database (Denmark)

    Bariani, Paolo

    The scanning electron microscope (SEM) has a big potential as a metrology instrument for micro and nanotechnology due to its unique combination of three imaging properties: • Lateral ultimate resolution down to 2nm • Large range of possible magnification levels ranging from a few hundred times...... that addresses the performance of 3D topography calculation based on surface topography imaging using secondary electrons and the Stereo Pair Technique....

  13. Investigation on traceability of 3D Scanning Electron Microscopy based on the Stereo Pair Technique

    DEFF Research Database (Denmark)

    Bariani, Paolo

    The scanning electron microscope (SEM) has a big potential as a metrology instrument for micro and nanotechnology due to its unique combination of three imaging properties: • Lateral ultimate resolution down to 2nm • Large range of possible magnification levels ranging from a few hundred times...... that addresses the performance of 3D topography calculation based on surface topography imaging using secondary electrons and the Stereo Pair Technique....

  14. Unexpected spatial intensity distributions and onset timing of solar electron events observed by closely spaced STEREO spacecraft

    Science.gov (United States)

    Klassen, A.; Dresing, N.; Gómez-Herrero, R.; Heber, B.; Müller-Mellin, R.

    2016-09-01

    We present multi-spacecraft observations of four solar electron events using measurements from the Solar Electron Proton Telescope (SEPT) and the Electron Proton Helium INstrument (EPHIN) on board the STEREO and SOHO spacecraft, respectively, occurring between 11 October 2013 and 1 August 2014, during the approaching superior conjunction period of the two STEREO spacecraft. At this time the longitudinal separation angle between STEREO-A (STA) and STEREO-B (STB) was less than 72°. The parent particle sources (flares) of the four investigated events were situated close to, in between, or to the west of the STEREO's magnetic footpoints. The STEREO measurements revealed a strong difference in electron peak intensities (factor ≤12) showing unexpected intensity distributions at 1 AU, although the two spacecraft had nominally nearly the same angular magnetic footpoint separation from the flaring active region (AR) or their magnetic footpoints were both situated eastwards from the parent particle source. Furthermore, the events detected by the two STEREO imply a strongly unexpected onset timing with respect to each other: the spacecraft magnetically best connected to the flare detected a later arrival of electrons than the other one. This leads us to suggest the concept of a rippled peak intensity distribution at 1 AU formed by narrow peaks (fingers) superposed on a quasi-uniform Gaussian distribution. Additionally, two of the four investigated solar energetic particle (SEP) events show a so-called circumsolar distribution and their characteristics make it plausible to suggest a two-component particle injection scenario forming an unusual, non-uniform intensity distribution at 1 AU.

  15. Calculating particle spectra from the solar electron and proton telescope onboard STEREO

    Energy Technology Data Exchange (ETDEWEB)

    Gieseler, Jan; Boettcher, Stephan; Heber, Bernd; Koehler, Jan [IEAP, CAU Kiel, Kiel (Germany)

    2013-07-01

    STEREO (Solar TErrestrial RElations Observatory) was launched on October 26, 2006. It consists of two spacecraft on heliocentric orbits, one preceding the Earth, the other following it. The Solar Electron and Proton Telescope (SEPT) onboard each of the two spacecraft is made up of two dual double-ended magnetic/foil particle telescopes which separate and measure electrons (from 30 to 400 keV) and ions, mainly protons and α-particles (from 70 keV to 2.2 MeV). Low energy ions are stopped by the thin foil which electrons can pass with an essentially unaltered spectrum. The magnet on the other side deflects electrons while ions still reach the detector. Up to now, SEPT energy spectra were obtained using defined energy channels from accelerator calibration measurements and geometric factors derived from Monte Carlo simulations. We try a different approach, applying inversion methods to calculate the energy spectra from the measurements, expecting higher accuracy and better separation of the different particle populations.

  16. Investigation on the traceability of three dimensional scanning electron microscope measurements based on the stereo-pair technique

    DEFF Research Database (Denmark)

    Bariani, Paolo; De Chiffre, Leonardo; Hansen, Hans Nørgaard

    2005-01-01

    An investigation was carried out concerning the traceability of dimensional measurements performed with the scanning electron microscope (SEM) using reconstruction of surface topography through stereo-photogrammetry. A theoretical description of the effects that the main instrumental variables...... with the scanning electron microscope (SEM) using reconstruction of surface topography through stereo-photogrammetry. A theoretical description of the effects that the main instrumental variables and measurement parameters have on the reconstruction accuracy of any point on the surface of the object being imaged......-dimensional topography of the type C roughness standards showed good agreement with the nominal profile wavelength values. An investigation was carried out concerning the traceability of dimensional measurements performed with the scanning electron microscope (SEM) using reconstruction of surface topography through...

  17. Electronically Enhanced Classroom Interaction.

    Science.gov (United States)

    Draper, Stephen; Cargill, Julie; Cutts, Quintin

    A design rationale for introducing electronic equipment (a group response system) for student interaction in lecture theaters is presented, linking the instructional design to theory. The effectiveness of the equipment for learning depends mostly on what pedagogic method is employed. Various alternative types are introduced, including: assessment;…

  18. Platform for enhanced light-graphene interaction length and miniaturizing fiber stereo-devices

    CERN Document Server

    Xu, Fei; Chen, Jin-hui; Chen, Ye; Lu, Yan-qing

    2014-01-01

    Sufficient light-matter interactions are important for waveguide-coupled graphene optoelectronic devices. Using a microfiber-based lab-on-a-rod technique, we present a platform for ultra-long light-graphene interaction and design graphene-integrated helical microfiber (MF) devices. Using this approach, we experimentally demonstrate an in-line stereo polarizer by wrapping an MF on a rod pretreated with a graphene sheet. The device operates as a broadband (450 nm wavelength) polarizer capable of achieving an extinction ratio (ER) as high as ~8 dB/coil in the telecommunication band. Furthermore, we extend this approach to successfully demonstrate a high-Q graphene-based single-polarization resonator, which operates with an ER of ~11 dB with excellent suppression of polarization noise. The fiber-coil resonator shows great potential for sensing applications and gyro-integration. By specializing the rod surface and coil geometry, we believe the preliminary results reported herein could contribute to advancing the r...

  19. Electron-electron interactions in disordered systems

    CERN Document Server

    Efros, AL

    1985-01-01

    ``Electron-Electron Interactions in Disordered Systems'' deals with the interplay of disorder and the Coulomb interaction. Prominent experts give state-of-the-art reviews of the theoretical and experimental work in this field and make it clear that the interplay of the two effects is essential, especially in low-dimensional systems.

  20. Large Amplitude Whistler Waves and Electron Acceleration in the Earth's Radiation Belts: A Review of STEREO and Wind Observations

    Science.gov (United States)

    Cattell, Cynthia; Breneman, A.; Goetz, K.; Kellogg, P.; Kersten, K.; Wygant, J.; Wilson, L. B., III; Looper, Mark D.; Blake, J. Bernard; Roth, I.

    2012-01-01

    One of the critical problems for understanding the dynamics of Earth's radiation belts is determining the physical processes that energize and scatter relativistic electrons. We review measurements from the Wind/Waves and STEREO S/Waves waveform capture instruments of large amplitude whistler-mode waves. These observations have provided strong evidence that large amplitude (100s mV/m) whistler-mode waves are common during magnetically active periods. The large amplitude whistlers have characteristics that are different from typical chorus. They are usually nondispersive and obliquely propagating, with a large longitudinal electric field and significant parallel electric field. We will also review comparisons of STEREO and Wind wave observations with SAMPEX observations of electron microbursts. Simulations show that the waves can result in energization by many MeV and/or scattering by large angles during a single wave packet encounter due to coherent, nonlinear processes including trapping. The experimental observations combined with simulations suggest that quasilinear theoretical models of electron energization and scattering via small-amplitude waves, with timescales of hours to days, may be inadequate for understanding radiation belt dynamics.

  1. Stereo Hysteresis Revisited

    Directory of Open Access Journals (Sweden)

    Christopher Tyler

    2012-05-01

    Full Text Available One of the most fascinating phenomena in stereopsis is the profound hysteresis effect reported by Fender and Julesz (1967, in which the depth percept persisted with increasing disparity long past the point at which depth was recovered with decreasing disparity. To control retinal disparity without vergence eye movements, they stabilized the stimuli on the retinas with an eye tracker. I now report that stereo hysteresis can be observed directly in printed stereograms simply by rotating the image. As the stereo image rotates, the horizontal disparities rotate to become vertical, then horizontal with inverted sign, and then vertical again before returning to the original orientation. The depth shows an interesting popout effect, almost as though the depth was turning on and off rapidly, despite the inherently sinusoidal change in the horizontal disparity vector. This stimulus was generated electronically in a circular format so that the random-dot field could be dynamically replaced, eliminating any cue to cyclorotation. Noise density was scaled with eccentricity to fade out the stimulus near fixation. For both the invariant and the dynamic noise, profound hysteresis of several seconds delay was found in six observers. This was far longer than the reaction time to respond to changes in disparity, which was less than a second. Purely horizontal modulation of disparity to match the horizontal vector component of the disparity rotation did not show the popout effect, which thus seems to be a function of the interaction between horizontal and vertical disparities and may be attributable to depth interpolation processes.

  2. Stereo pairs in Astrophysics

    Science.gov (United States)

    Vogt, Frédéric; Wagner, Alexander Y.

    2012-01-01

    Stereoscopic visualization is seldom used in Astrophysical publications and presentations compared to other scientific fields, e.g., Biochemistry, where it has been recognized as a valuable tool for decades. We put forth the view that stereo pairs can be a useful tool for the Astrophysics community in communicating a truer representation of astrophysical data. Here, we review the main theoretical aspects of stereoscopy, and present a tutorial to easily create stereo pairs using Python. We then describe how stereo pairs provide a way to incorporate 3D data in 2D publications of standard journals. We illustrate the use of stereo pairs with one conceptual and two Astrophysical science examples: an integral field spectroscopy study of a supernova remnant, and numerical simulations of a relativistic AGN jet. We also use these examples to make the case that stereo pairs are not merely an ostentatious way to present data, but an enhancement in the communication of scientific results in publications because they provide the reader with a realistic view of multi-dimensional data, be it of observational or theoretical nature. In recognition of the ongoing 3D expansion in the commercial sector, we advocate an increased use of stereo pairs in Astrophysics publications and presentations as a first step towards new interactive and multi-dimensional publication methods.

  3. Interactive stereo games to improve vision in children with amblyopia using dichoptic stimulation

    Science.gov (United States)

    Herbison, Nicola; Ash, Isabel M.; MacKeith, Daisy; Vivian, Anthony; Purdy, Jonathan H.; Fakis, Apostolos; Cobb, Sue V.; Hepburn, Trish; Eastgate, Richard M.; Gregson, Richard M.; Foss, Alexander J. E.

    2015-03-01

    Amblyopia is a common condition affecting 2% of all children and traditional treatment consists of either wearing a patch or penalisation. We have developed a treatment using stereo technology, not to provide a 3D image but to allow dichoptic stimulation. This involves presenting an image with the same background to both eyes but with features of interest removed from the image presented to the normal eye with the aim to preferentially stimulated visual development in the amblyopic, or lazy, eye. Our system, called I-BiT can use either a game or a video (DVD) source as input. Pilot studies show that this treatment is effective with short treatment times and has proceeded to randomised controlled clinical trial. The early indications are that the treatment has a high degree of acceptability and corresponding good compliance.

  4. Uncertainty evaluation for three-dimensional scanning electron microscope reconstructions based on the stereo-pair technique

    DEFF Research Database (Denmark)

    Carli, Lorenzo; Genta, G; Cantatore, Angela

    2011-01-01

    3D-SEM is a method, based on the stereophotogrammetry technique, which obtains three-dimensional topographic reconstructions starting typically from two SEM images, called the stereo-pair. In this work, a theoretical uncertainty evaluation of the stereo-pair technique, according to GUM (Guide to ...

  5. Visual capture of a stereo sound: Interactions between cue reliability, sound localization variability, and cross-modal bias.

    Science.gov (United States)

    Montagne, Christopher; Zhou, Yi

    2016-07-01

    Multisensory interactions involve coordination and sometimes competition between multiple senses. Vision usually dominates audition in spatial judgments when light and sound stimuli are presented from two different physical locations. This study investigated the influence of vision on the perceived location of a phantom sound source placed in a stereo sound field using a pair of loudspeakers emitting identical signals that were delayed or attenuated relative to each other. Results show that although a similar horizontal range (+/-45°) was reported for timing-modulated and level-modulated signals, listeners' localization performance showed greater variability for the timing signals. When visual stimuli were presented simultaneously with the auditory stimuli, listeners showed stronger visual bias for timing-modulated signals than level-modulated and single-speaker control signals. Trial-to-trial errors remained relatively stable over time, suggesting that sound localization uncertainty has an immediate and long-lasting effect on the across-modal bias. Binaural signal analyses further reveal that interaural differences of time and intensity-the two primary cues for sound localization in the azimuthal plane-are inherently more ambiguous for signals placed using timing. These results suggest that binaural ambiguity is intrinsically linked with localization variability and the strength of cross-modal bias in sound localization.

  6. Electron-molecule interactions and their applications

    CERN Document Server

    Christophorou, L G

    1984-01-01

    Electron-Molecule Interactions and Their Applications, Volume 2 provides a balanced and comprehensive account of electron-molecule interactions in dilute and dense gases and liquid media. This book consists of six chapters. Chapter 1 deals with electron transfer reactions, while Chapter 2 discusses electron-molecular positive-ion recombination. The electron motion in high-pressure gases and electron-molecule interactions from single- to multiple-collision conditions is deliberated in Chapter 3. In Chapter 4, knowledge on electron-molecule interactions in gases is linked to that on similar proc

  7. Normative 3D opto-electronic stereo-photogrammetric posture and spine morphology data in young healthy adult population.

    Science.gov (United States)

    D'Amico, Moreno; Kinel, Edyta; Roncoletta, Piero

    2017-01-01

    Observational cross-sectional study. The current study aims to yield normative data: i.e., the physiological standard for 30 selected quantitative 3D parameters that accurately capture and describe a full-skeleton, upright-standing attitude. Specific and exclusive consideration was given to three distinct categories: postural, spine morphology and pelvic parameters. To capture such 3D parameters, the authors selected a non-ionising 3D opto-electronic stereo-photogrammetric approach. This required the identification and measurement of 27 body landmarks, each specifically tagged with a skin marker. As subjects for the measurement of these parameters, a cohort of 124 asymptomatic young adult volunteers was recruited. All parameters were identified and measured within this group. Postural and spine morphology data have been compared between genders. In this regard, only five statistically significant differences were found: pelvis width, pelvis torsion, the "lumbar" lordosis angle value, the lumbar curve length, and the T12-L5 anatomically-bound lumbar angle value. The "thoracic" kyphosis mean angle value was the same in both sexes and, even if, derived from skin markers placed on spinous processes it resulted in perfect agreement with the X-ray based literature. As regards lordosis, a direct comparison was more difficult because methods proposed in the literature differ as to the number and position of vertebrae under consideration, and their related angle values. However, when the L1 superior-L5 inferior end plate Cobb angle was considered, these results aligned strongly with the existing literature. Asymmetry was a standard postural-spinal feature for both sexes. Each subject presented some degree of leg length discrepancy (LLD) with μ = 9.37mm. This was associated with four factors: unbalanced posture and/or underfoot loads, spinal curvature in the frontal plane, and pelvis torsion. This led to the additional study of the effect of LLD equalisation influence on

  8. Four dimensional observations of clouds from geosynchronous orbit using stereo display and measurement techniques on an interactive information processing system

    Science.gov (United States)

    Hasler, A. F.; Desjardins, M.; Shenk, W. E.

    1979-01-01

    Simultaneous Geosynchronous Operational Environmental Satellite (GOES) 1 km resolution visible image pairs can provide quantitative three dimensional measurements of clouds. These data have great potential for severe storms research and as a basic parameter measurement source for other areas of meteorology (e.g. climate). These stereo cloud height measurements are not subject to the errors and ambiguities caused by unknown cloud emissivity and temperature profiles that are associated with infrared techniques. This effort describes the display and measurement of stereo data using digital processing techniques.

  9. Comparison of coronal electron density distributions from MLSO/MK4, STEREO/SECCHI-COR1, SOHO/LASCO-C2, and SOHO/UVCS

    Science.gov (United States)

    Lee, Jae-Ok; Cho, Kyung-Suk; Lee, Jin-Yi; Lee, Kyoung-Sun; Jang, Soojeong; Kim, Roksoon; Moon, Yong-Jae

    2017-08-01

    The coronal electron density is a fundamental and important physical quantity in solar physics. In this study, we compare coronal electron density distributions (CEDDs) derived from polarized brightness (pB) observations (MLSO/MK4 coronameter, STEREO/SECCHI-COR1 and SOHO/LASCO-C2 Coronagraphs) and one spectroscopic observation (SOHO/UVCS). For this, we consider data from January to August 2007 with the following conditions: the separation angle between the either of the STEREO spacecraft and Earth is less than 10 degrees and the observation time differences from one another are less than 1 minutes. In the pB observations, the CEDDs can be estimated by using inversion methods (Van de Hulst inversion for MK4 and LASCO-C2 pB data, and spherically symmetric polynomial approximation inversion for COR1 pB data). In the spectroscopic observation, we use the ratio of radiative and collisional components of the O vi doublet (O vi 1032 Å and 1037.6 Å) to estimate the CEDDs. We will show you some results about the estimated CEDDs and their dependence on different coronal regions such as backgournd corona and streamers.

  10. Electron-wall Interaction in Hall Thrusters

    Energy Technology Data Exchange (ETDEWEB)

    Y. Raitses; D. Staack; M. Keidar; N.J. Fisch

    2005-02-11

    Electron-wall interaction effects in Hall thrusters are studied through measurements of the plasma response to variations of the thruster channel width and the discharge voltage. The discharge voltage threshold is shown to separate two thruster regimes. Below this threshold, the electron energy gain is constant in the acceleration region and therefore, secondary electron emission (SEE) from the channel walls is insufficient to enhance electron energy losses at the channel walls. Above this voltage threshold, the maximum electron temperature saturates.

  11. Explorers of the Universe: Interactive Electronic Network

    Science.gov (United States)

    Alvarez, Marino C.; Burks, Geoffrey; Busby, Michael R.; Cannon, Tiffani; Sotoohi, Goli; Wade, Montanez

    2000-01-01

    This paper details how the Interactive Electronic Network is being utilized by secondary and postsecondary students, and their teachers and professors, to facilitate learning and understanding. The Interactive Electronic Network is couched within the Explorers of the Universe web site in a restricted portion entitled Gateway.

  12. Electron-phonon interactions from first principles

    Science.gov (United States)

    Giustino, Feliciano

    2017-01-01

    This article reviews the theory of electron-phonon interactions in solids from the point of view of ab initio calculations. While the electron-phonon interaction has been studied for almost a century, predictive nonempirical calculations have become feasible only during the past two decades. Today it is possible to calculate from first principles many materials properties related to the electron-phonon interaction, including the critical temperature of conventional superconductors, the carrier mobility in semiconductors, the temperature dependence of optical spectra in direct and indirect-gap semiconductors, the relaxation rates of photoexcited carriers, the electron mass renormalization in angle-resolved photoelectron spectra, and the nonadiabatic corrections to phonon dispersion relations. In this article a review of the theoretical and computational framework underlying modern electron-phonon calculations from first principles as well as landmark investigations of the electron-phonon interaction in real materials is given. The first part of the article summarizes the elementary theory of electron-phonon interactions and their calculations based on density-functional theory. The second part discusses a general field-theoretic formulation of the electron-phonon problem and establishes the connection with practical first-principles calculations. The third part reviews a number of recent investigations of electron-phonon interactions in the areas of vibrational spectroscopy, photoelectron spectroscopy, optical spectroscopy, transport, and superconductivity.

  13. Interaction between photons and electrons

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    By using a path-integral theory, the photoemission spectra of the electron-phonon (e-ph) coupled systems are calculated exactly. The spectral properties of the e-ph coupled systems based on the 1D and 2D Holstein models are systematically studied under various conditions. The electronic band structure is found to be greatly modified by the multiple scattering effect of electron with phonons, so as to produce a spectral evolution from broad Gaussian at band bottom to two-headed Lorentzian near the Fermi energy. This evolution reflects a transition of electronic states from localized incoherent one to the extended coherent one near the Fermi energy. The results qualitatively agree with recent experiments of high resolution ARPES on the Be (0001) surface and Bi2Sr2CaCu2O8.

  14. Nanoelectromechanical Heat Engine Based on Electron-Electron Interaction

    Science.gov (United States)

    Vikström, A.; Eriksson, A. M.; Kulinich, S. I.; Gorelik, L. Y.

    2016-12-01

    We theoretically show that a nanoelectromechanical system can be mechanically actuated by a heat flow through it via an electron-electron interaction. In contrast to most known actuation mechanisms in similar systems, this new mechanism does not involve an electronic current nor external ac fields. Instead, the mechanism relies on deflection-dependent tunneling rates and a heat flow which is mediated by an electron-electron interaction while an electronic current through the device is prohibited by, for instance, a spin-valve effect. Therefore, the system resembles a nanoelectromechanical heat engine. We derive a criterion for the mechanical instability and estimate the amplitude of the resulting self-sustained oscillations. Estimations show that the suggested phenomenon can be studied using available experimental techniques.

  15. The Electron Transport Chain: An Interactive Simulation

    Science.gov (United States)

    Romero, Chris; Choun, James

    2014-01-01

    This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular…

  16. The Electron Transport Chain: An Interactive Simulation

    Science.gov (United States)

    Romero, Chris; Choun, James

    2014-01-01

    This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular…

  17. Transient Structures and Stream Interaction Regions in the Solar Wind: Results from EISCAT Interplanetary Scintillation, STEREO HI and Venus Express ASPERA-4 Measurements

    CERN Document Server

    Dorrian, Gareth; Davies, Jackie; Rouillard, Alexi; Fallows, Richard; Whittaker, Ian; Brown, Daniel; Harrison, Richard; Davis, Chris; Grande, Manuel; 10.1007/s11207-010-9599-z

    2012-01-01

    We discuss the detection and evolution of a complex series of transient and quasi-static solar wind structures in the days following the well-known comet 2P / Encke tail disconnection event in April 2007. The evolution of transient solar wind structures ranging in size from 106 km was characterized using one-minute time resolution observation of Interplanetary Scintillation (IPS) made using the European Incoherent SCA Tter (EISCA T) radar system. Simultaneously, the global structure and evolution of these features was characterized by the Heliospheric Imagers (HI) on the Solar TERrestrial RElations Observatory (STEREO) spacecraft, placing the IPS observations in context. Of particular interest was the observation of one transient in the slow wind apparently being swept up and entrained by a Stream Interaction Region (SIR). The SIR itself was later detected in-situ at Venus by the Analyser of Space Plasma and Energetic Atoms (ASPERA-4) instrument on the Venus Express (VEX) spacecraft. The availability of such...

  18. Electron correlation by polarization of interacting densities

    CERN Document Server

    Whitten, Jerry L

    2016-01-01

    Coulomb interactions that occur in electronic structure calculations are correlated by allowing basis function components of the interacting densities to polarize, thereby reducing the magnitude of the interaction. Exchange integrals of molecular orbitals are not correlated. The modified Coulomb interactions are used in single-determinant or configuration interaction calculations. The objective is to account for dynamical correlation effects without explicitly introducing higher spherical harmonic functions into the molecular orbital basis. Molecular orbital densities are decomposed into a distribution of spherical components that conserve the charge and each of the interacting components is considered as a two-electron wavefunction embedded in the system acted on by an average field Hamiltonian plus . A method of avoiding redundancy is described. Applications to atoms, negative ions and molecules representing different types of bonding and spin states are discussed.

  19. Electromagnetic interaction of relativistic electrons in matter; Interaction electromagnetique d`electrons relativistes dans la matiere

    Energy Technology Data Exchange (ETDEWEB)

    Artru, X. [Inst. de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France); Collaboration: IPN-Lyon, IRMM (Gell), LURE (Orsay); Collaboration: IPN-Lyon, LAL and IEF (Orsay), HIP (Helsinki), INFN (Frascati, Milan)

    1998-12-31

    We have studied different effects related to electromagnetic interaction of relativistic electrons in matter and investigated their use in beam profile measurements. (authors) 4 refs. Short communication

  20. Tunable electronic interactions between anions and perylenediimide.

    Science.gov (United States)

    Goodson, Flynt S; Panda, Dillip K; Ray, Shuvasree; Mitra, Atanu; Guha, Samit; Saha, Sourav

    2013-08-07

    Over the past decade anion-π interaction has emerged as a new paradigm of supramolecular chemistry of anions. Taking advantage of the electronic nature of anion-π interaction, we have expanded its boundaries to charge-transfer (CT) and formal electron transfer (ET) events by adjusting the electron-donating and accepting abilities of anions and π-acids, respectively. To establish that ET, CT, and anion-π interactions could take place between different anions and π-acids as long as their electronic and structural properties are conducive, herein, we introduce 3,4,9,10-perylenediimide (PDI-1) that selectively undergoes thermal ET from strong Lewis basic hydroxide and fluoride anions, but remains electronically and optically silent to poor Lewis basic anions, as ET and CT events are turned OFF. These interactions have been fully characterized by UV/Vis, NMR, and EPR spectroscopies. These results demonstrate the generality of anion-induced ET events in aprotic solvents and further refute a notion that strong Lewis basic hydroxide and fluoride ions can only trigger nucleophilic attack to form covalent bonds instead of acting as sacrificial electron donors to π-acids under appropriate conditions.

  1. Solar Eclipse, STEREO Style

    Science.gov (United States)

    2007-01-01

    There was a transit of the Moon across the face of the Sun - but it could not be seen from Earth. This sight was visible only from the STEREO-B spacecraft in its orbit about the sun, trailing behind the Earth. NASA's STEREO mission consists of two spacecraft launched in October, 2006 to study solar storms. The transit starts at 1:56 am EST and continued for 12 hours until 1:57 pm EST. STEREO-B is currently about 1 million miles from the Earth, 4.4 times farther away from the Moon than we are on Earth. As the result, the Moon will appear 4.4 times smaller than what we are used to. This is still, however, much larger than, say, the planet Venus appeared when it transited the Sun as seen from Earth in 2004. This alignment of STEREO-B and the Moon is not just due to luck. It was arranged with a small tweak to STEREO-B's orbit last December. The transit is quite useful to STEREO scientists for measuring the focus and the amount of scattered light in the STEREO imagers and for determining the pointing of the STEREO coronagraphs. The Sun as it appears in these the images and each frame of the movie is a composite of nearly simultaneous images in four different wavelengths of extreme ultraviolet light that were separated into color channels and then recombined with some level of transparency for each.

  2. Solar Eclipse, STEREO Style

    Science.gov (United States)

    2007-01-01

    There was a transit of the Moon across the face of the Sun - but it could not be seen from Earth. This sight was visible only from the STEREO-B spacecraft in its orbit about the sun, trailing behind the Earth. NASA's STEREO mission consists of two spacecraft launched in October, 2006 to study solar storms. The transit starts at 1:56 am EST and continued for 12 hours until 1:57 pm EST. STEREO-B is currently about 1 million miles from the Earth, 4.4 times farther away from the Moon than we are on Earth. As the result, the Moon will appear 4.4 times smaller than what we are used to. This is still, however, much larger than, say, the planet Venus appeared when it transited the Sun as seen from Earth in 2004. This alignment of STEREO-B and the Moon is not just due to luck. It was arranged with a small tweak to STEREO-B's orbit last December. The transit is quite useful to STEREO scientists for measuring the focus and the amount of scattered light in the STEREO imagers and for determining the pointing of the STEREO coronagraphs. The Sun as it appears in these the images and each frame of the movie is a composite of nearly simultaneous images in four different wavelengths of extreme ultraviolet light that were separated into color channels and then recombined with some level of transparency for each.

  3. Stereo pairs in Astrophysics

    CERN Document Server

    Vogt, Frédéric

    2011-01-01

    Stereoscopic visualization is seldom used in Astrophysical publications and presentations compared to other scientific fields, e.g., Biochemistry, where it has been recognized as a valuable tool for decades. We put forth the view that stereo pairs can be a useful tool for the Astrophysics community in communicating a truer representation of astrophysical data. Here, we review the main theoretical aspects of stereoscopy, and present a tutorial to easily create stereo pairs using Python. We then describe how stereo pairs provide a way to incorporate 3D data in 2D publications of standard journals. We illustrate the use of stereo pairs with one conceptual and two Astrophysical science examples: an integral field spectroscopy study of a supernova remnant, and numerical simulations of a relativistic AGN jet. We also use these examples to make the case that stereo pairs are not merely an ostentatious way to present data, but an enhancement in the communication of scientific results in publications because they prov...

  4. Electron Donor Acceptor Interactions. Final Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-08-16

    The Gordon Research Conference (GRC) on Electron Donor Acceptor Interactions was held at Salve Regina University, Newport, Rhode Island, 8/11-16/02. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  5. JAVA Stereo Display Toolkit

    Science.gov (United States)

    Edmonds, Karina

    2008-01-01

    This toolkit provides a common interface for displaying graphical user interface (GUI) components in stereo using either specialized stereo display hardware (e.g., liquid crystal shutter or polarized glasses) or anaglyph display (red/blue glasses) on standard workstation displays. An application using this toolkit will work without modification in either environment, allowing stereo software to reach a wider audience without sacrificing high-quality display on dedicated hardware. The toolkit is written in Java for use with the Swing GUI Toolkit and has cross-platform compatibility. It hooks into the graphics system, allowing any standard Swing component to be displayed in stereo. It uses the OpenGL graphics library to control the stereo hardware and to perform the rendering. It also supports anaglyph and special stereo hardware using the same API (application-program interface), and has the ability to simulate color stereo in anaglyph mode by combining the red band of the left image with the green/blue bands of the right image. This is a low-level toolkit that accomplishes simply the display of components (including the JadeDisplay image display component). It does not include higher-level functions such as disparity adjustment, 3D cursor, or overlays all of which can be built using this toolkit.

  6. Stereo 3D spatial phase diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jinwu, E-mail: kangjw@tsinghua.edu.cn; Liu, Baicheng, E-mail: liubc@tsinghua.edu.cn

    2016-07-15

    Phase diagrams serve as the fundamental guidance in materials science and engineering. Binary P-T-X (pressure–temperature–composition) and multi-component phase diagrams are of complex spatial geometry, which brings difficulty for understanding. The authors constructed 3D stereo binary P-T-X, typical ternary and some quaternary phase diagrams. A phase diagram construction algorithm based on the calculated phase reaction data in PandaT was developed. And the 3D stereo phase diagram of Al-Cu-Mg ternary system is presented. These phase diagrams can be illustrated by wireframe, surface, solid or their mixture, isotherms and isopleths can be generated. All of these can be displayed by the three typical display ways: electronic shutter, polarization and anaglyph (for example red-cyan glasses). Especially, they can be printed out with 3D stereo effect on paper, and watched by the aid of anaglyph glasses, which makes 3D stereo book of phase diagrams come to reality. Compared with the traditional illustration way, the front of phase diagrams protrude from the screen and the back stretches far behind of the screen under 3D stereo display, the spatial structure can be clearly and immediately perceived. These 3D stereo phase diagrams are useful in teaching and research. - Highlights: • Stereo 3D phase diagram database was constructed, including binary P-T-X, ternary, some quaternary and real ternary systems. • The phase diagrams can be watched by active shutter or polarized or anaglyph glasses. • The print phase diagrams retains 3D stereo effect which can be achieved by the aid of anaglyph glasses.

  7. LROC NAC Stereo Anaglyphs

    Science.gov (United States)

    Mattson, S.; McEwen, A. S.; Speyerer, E.; Robinson, M. S.

    2012-12-01

    The Lunar Reconnaissance Orbiter Camera Narrow Angle Camera (LROC NAC) acquires high resolution (50 to 200 cm pixel scale) images of the Moon. In operation since June 2009, LROC NAC acquires geometric stereo pairs by rolling off-nadir on subsequent orbits. A new automated processing system currently in development will produce anaglyphs from most of the NAC geometric stereo pairs. An anaglyph is an image formed by placing one image from the stereo pair in the red channel, and the other image from the stereo pair in the green and blue channels, so that together with red-blue or red-cyan glasses, the 3D information in the pair can be readily viewed. These new image products will make qualitative interpretation of the lunar surface in 3D more accessible, without the need for intensive computational resources or special equipment. The LROC NAC is composed of two separate pushbroom CCD cameras (NAC L and R) aligned to increase the full swath width to 5 km from an altitude of 50 km. Development of the anaglyph processing system incorporates stereo viewing geometry, proper alignment of the NAC L and R frames, and optimal contrast normalization of the stereo pair to minimize extreme brightness differences, which can make stereo viewing difficult in an anaglyph. The LROC NAC anaglyph pipeline is based on a similar automated system developed for the HiRISE camera, on the Mars Reconnaissance Orbiter. Improved knowledge of camera pointing and spacecraft position allows for the automatic registration of the L and R frames by map projecting them to a polar stereographic projection. One half of the stereo pair must then be registered to the other so there is no offset in the vertical (y) direction. Stereo viewing depends on parallax only in the horizontal (x) direction. High resolution LROC NAC anaglyphs will be made available to the lunar science community and to the public on the LROC web site (http://lroc.sese.asu.edu).

  8. Parametric Coding of Stereo Audio

    Directory of Open Access Journals (Sweden)

    Erik Schuijers

    2005-06-01

    Full Text Available Parametric-stereo coding is a technique to efficiently code a stereo audio signal as a monaural signal plus a small amount of parametric overhead to describe the stereo image. The stereo properties are analyzed, encoded, and reinstated in a decoder according to spatial psychoacoustical principles. The monaural signal can be encoded using any (conventional audio coder. Experiments show that the parameterized description of spatial properties enables a highly efficient, high-quality stereo audio representation.

  9. Stereo and scanning electron microscopy of in-shell Brazil nut (Bertholletia excelsa H.B.K.): part two-surface sound nut fungi spoilage susceptibility.

    Science.gov (United States)

    Scussel, Vildes M; Manfio, Daniel; Savi, Geovana D; Moecke, Elisa H S

    2014-11-01

    This work reports the in-shell Brazil nut spoilage susceptible morpho-histological characteristics and fungi infection (shell, edible part, and brown skin) through stereo and scanning electron microscopies (SEM). The following characteristics related to shell (a) morphology-that allow fungi and insects' entrance to inner nut, and (b) histology-that allow humidity absorption, improving environment conditions for living organisms development, were identified. (a.1) locule in testae-the nut navel, which is a cavity formed during nut detaching from pods (located at 1.0 to 2.0/4th of the shell B&C nut faces linkage). It allows the nut brown skin (between shell and edible part) first contact to the external environment, through the (a.2) nut channel-the locule prolongation path, which has the water/nutrients cambium function for their transport and distribution to the inner seed (while still on the tree/pod). Both, locule followed by the channel, are the main natural entrance of living organisms (fungi and insects), including moisture to the inner seed structures. In addition, the (a.3) nut shell surface-which has a crinkled and uneven surface morphology-allows water absorption, thus adding to the deterioration processes too. The main shell histological characteristic, which also allows water absorption (thus improving environment conditions for fungi proliferation), is the (b.1) cell wall porosity-the multilayered wall and porous rich cells that compose the shell faces double tissue layers and the (b.2) soft tissue-the mix of tissues 2 faces corner/linkage. This work also shows in details the SEM nut spoilage susceptible features highly fungi infected with hyphae and reproductive structures distribution. © 2014 Institute of Food Technologists®

  10. Electronic implementations of interaction-free measurements

    Science.gov (United States)

    Chirolli, L.; Strambini, E.; Giovannetti, V.; Taddei, F.; Piazza, V.; Fazio, R.; Beltram, F.; Burkard, G.

    2010-07-01

    Three different implementations of interaction-free measurements (IFMs) in solid-state nanodevices are discussed. The first one is based on a series of concatenated Mach-Zehnder interferometers, in analogy to optical-IFM setups. The second one consists of a single interferometer and concatenation is achieved in the time domain making use of a quantized electron emitter. The third implementation consists of an asymmetric Aharonov-Bohm ring. For all three cases we show that the presence of a dephasing source acting on one arm of the interferometer can be detected without degrading the coherence of the measured current. Electronic implementations of IFMs in nanoelectronics may play a fundamental role as very accurate and noninvasive measuring schemes for quantum devices.

  11. Gas–Electron Interaction in the ETEM

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal; Beleggia, Marco

    2016-01-01

    simple picture of a plane wave interacting with the sample of interest is no longer valid. Furthermore, the exit wave from the sample is altered by scattering events taking place after the sample in the direction of propagation. In this chapter, the effect of the increased gas pressure between the pole...... pieces in an aberration-corrected highresolution transmission electron microscope is discussed in order to shine some light on the additional phenomena occurring in ETEM compared to conventional HRTEM. Both direct effects on the image quality and more indirect effects rising from gas ionization...

  12. Interaction of electron neutrino with LSD detector

    Science.gov (United States)

    Ryazhskaya, O. G.; Semenov, S. V.

    2016-06-01

    The interaction of electron neutrino flux, originating in the rotational collapse mechanism on the first stage of Supernova burst, with the LSD detector components, such as 56Fe (a large amount of this metal is included in as shielding material) and liquid scintillator barNnH2n+2, is being investigated. Both charged and neutral channels of neutrino reaction with 12barN and 56Fe are considered. Experimental data, giving the possibility to extract information for nuclear matrix elements calculation are used. The number of signals, produced in LSD by the neutrino pulse of Supernova 1987A is determined. The obtained results are in good agreement with experimental data.

  13. Metastable and spin-polarized states in electron systems with localized electron-electron interaction

    Science.gov (United States)

    Sablikov, Vladimir A.; Shchamkhalova, Bagun S.

    2014-05-01

    We study the formation of spontaneous spin polarization in inhomogeneous electron systems with pair interaction localized in a small region that is not separated by a barrier from surrounding gas of non-interacting electrons. Such a system is interesting as a minimal model of a quantum point contact in which the electron-electron interaction is strong in a small constriction coupled to electron reservoirs without barriers. Based on the analysis of the grand potential within the self-consistent field approximation, we find that the formation of the polarized state strongly differs from the Bloch or Stoner transition in homogeneous interacting systems. The main difference is that a metastable state appears in the critical point in addition to the globally stable state, so that when the interaction parameter exceeds a critical value, two states coexist. One state has spin polarization and the other is unpolarized. Another feature is that the spin polarization increases continuously with the interaction parameter and has a square-root singularity in the critical point. We study the critical conditions and the grand potentials of the polarized and unpolarized states for one-dimensional and two-dimensional models in the case of extremely small size of the interaction region.

  14. Sterile neutrino search in the STEREO experiment

    Energy Technology Data Exchange (ETDEWEB)

    Buck, Christian; Lindner, Manfred; Roca, Christian [MPIK (Germany)

    2016-07-01

    In neutrino oscillations, a canonical understanding has been established during the last decades after the measurement of the mixing angles θ{sub 12}, θ{sub 23}, θ{sub 13} via solar, atmospheric and, most recently, reactor neutrinos. However, the re-evaluation of the reactor neutrino theoretical flux has forced a re-analysis of most reactor neutrino measurements at short distances. This has led to an unexpected experimental deficit of neutrinos with respect to the theory that needs to be accommodated, commonly known as the ''reactor neutrino anomaly''. This deficit can be interpreted as the existence of a light sterile neutrino state into which reactor neutrinos oscillate at very short distances. The STEREO experiment aims to find an evidence of such oscillations. The ILL research reactor in Grenoble (France) operates at a power of 58MW and provides a large flux of electron antineutrinos with an energy range of a few MeV. These neutrinos will be detected in a 2000 liter organic liquid scintillator detector doped with Gadolinium and consisting of 6 cells stacked along the direction of the core. Given the proximity of the detector, neutrinos will only travel a few meters until they interact with the scintillator. The detector will be placed about 10 m from the reactor core, allowing STEREO to be sensitive to oscillations into the above mentioned neutrino sterile state. The project presents a high potential for a discovery that would impact deeply the paradigms of neutrino oscillations and in consequence the current understanding of particle physics and cosmology.

  15. Manifestation of nonlocal electron-electron interaction in graphene

    Science.gov (United States)

    Ulstrup, Søren; Schüler, Malte; Bianchi, Marco; Fromm, Felix; Raidel, Christian; Seyller, Thomas; Wehling, Tim; Hofmann, Philip

    2016-08-01

    Graphene is an ideal platform to study many-body effects due to its semimetallic character and the possibility to dope it over a wide range. Here we study the width of graphene's occupied π band as a function of doping using angle-resolved photoemission. Upon increasing electron doping, we observe the expected shift of the band to higher binding energies. However, this shift is not rigid and the bottom of the band moves less than the Dirac point. We show that the observed shift cannot be accounted for by single-particle effects and local self-energies alone, but that nonlocal many-body effects, in particular exchange interactions, must be taken into account.

  16. Chiral Sensitivity in Electron-Molecule Interactions

    Science.gov (United States)

    Dreiling, Joan

    2015-09-01

    All molecular forms of life possess a chiral asymmetry, with amino acids and sugars found respectively in L- and D-enantiomers only. The primordial origin of this enantiomeric excess is unknown. One possible explanation is given by the Vester- Ulbricht hypothesis, which suggests that left-handed electrons present in beta-radiation, produced by parity-violating weak decays, interacted with biological precursors and preferentially destroyed one of the two enantiomers. Experimental tests of this idea have thus far yielded inconclusive results. We show direct evidence for chirally-dependent bond breaking through a dissociative electron attachment (DEA) reaction when spin-polarized electrons are incident on gas-phase chiral molecules. This provides unambiguous evidence for a well-defined, chirally-sensitive destructive molecular process and, as such, circumstantial evidence for the Vester-Ulbricht hypothesis. I will also present the results of our systematic study of the DEA asymmetry for different chiral halocamphor molecules. Three halocamphor molecules were investigated: 3-bromocamphor (C10H15BrO), 3-iodocamphor(C10H15IO), and 10-iodocamphor. The DEA asymmetries collected for bromocamphor and iodocamphor are qualitatively different, suggesting that the atomic number of the heaviest atom in the molecule plays a crucial role in the asymmetric interactions. The DEA asymmetry data for 3- and 10-iodocamphor have the same qualitative behavior, but the 10-iodocamphor asymmetry is about twice as large at the lowest energies investigated, so the location of the heavy atom in the camphor molecule also affects the asymmetries. This work was performed at the University of Nebraska-Lincoln. This project is funded by NSF Grant PHY-1206067.

  17. Vibrationally dependent electron-electron interactions in resonant electron transport through single-molecule junctions

    Science.gov (United States)

    Erpenbeck, A.; Härtle, R.; Bockstedte, M.; Thoss, M.

    2016-03-01

    We investigate the role of electronic-vibrational coupling in resonant electron transport through single-molecule junctions, taking into account that the corresponding coupling strengths may depend on the charge and excitation state of the molecular bridge. Within an effective-model Hamiltonian approach for a molecule with multiple electronic states, this requires to extend the commonly used model and include vibrationally dependent electron-electron interaction. We use Born-Markov master equation methods and consider selected models to exemplify the effect of the additional interaction on the transport characteristics of a single-molecule junction. In particular, we show that it has a significant influence on local cooling and heating mechanisms, it may result in negative differential resistance, and it may cause pronounced asymmetries in the conductance map of a single-molecule junction.

  18. Study of electron-positron interactions

    Energy Technology Data Exchange (ETDEWEB)

    Abashian, A.; Gotow, K.; Philonen, L.

    1990-09-15

    For the past seven years, this group has been interested in the study of tests of the Standard Model of Electroweak interactions. The program has centered about the AMY experiment which examines the nature of the final state products in electron-positron collisions in the center of mass energy range near 60 GeV. Results of these measurements have shown a remarkable consistency with the predictions of the minimal model of 3 quark and lepton generations and single charged and neutral intermediate bosons. No new particles or excited states have been observed nor has any evidence for departures in cross sections or angular asymmetries from expectations been observed. These conclusions have been even more firmly established by the higher energy results from the LEP and SLC colliders at center of mass energies of about 90 GeV. Our focus is shifting to the neutrino as a probe to electroweak interactions. The relative merit of attempting to observe neutrinos from point sources versus observing neutrinos generally is not easy to predict. The improved ability to interpret is offset by the probably episodic nature of the emission and irreproducibility of the results. In this phase of development, it is best to be sensitive to both sources of neutrinos. As a second phase of our program at Virginia Tech, we are studying the feasibility of detecting cosmic ray neutrinos in a proposed experiment which we have called NOVA. the results of the test setup will be instrumental in developing an optimum design. A third program we are involved in is the MEGA experiment at Los Alamos, an experiment to place a limit on the rate of muon decay to electron plus photon which is forbidden by the Standard Model.

  19. Approaches for Stereo Matching

    Directory of Open Access Journals (Sweden)

    Takouhi Ozanian

    1995-04-01

    Full Text Available This review focuses on the last decade's development of the computational stereopsis for recovering three-dimensional information. The main components of the stereo analysis are exposed: image acquisition and camera modeling, feature selection, feature matching and disparity interpretation. A brief survey is given of the well known feature selection approaches and the estimation parameters for this selection are mentioned. The difficulties in identifying correspondent locations in the two images are explained. Methods as to how effectively to constrain the search for correct solution of the correspondence problem are discussed, as are strategies for the whole matching process. Reasons for the occurrence of matching errors are considered. Some recently proposed approaches, employing new ideas in the modeling of stereo matching in terms of energy minimization, are described. Acknowledging the importance of computation time for real-time applications, special attention is paid to parallelism as a way to achieve the required level of performance. The development of trinocular stereo analysis as an alternative to the conventional binocular one, is described. Finally a classification based on the test images for verification of the stereo matching algorithms, is supplied.

  20. Electron transport through nano-MOSFET in presence of electron-electron interaction

    Directory of Open Access Journals (Sweden)

    Hamidreza Simchi

    2013-03-01

    Full Text Available We investigate the effect of electron-electron interaction on voltage distribution, charge distribution and current-voltage curve of two dimensional nano-MOSFETs with dimension equal to 1 × 1 nm2, 3 × 3 nm2, and 6 × 6 nm2 by using non-equilibrium Green function method. It is shown that the turn on voltage increases by decreasing the size of sample because of size quantization. Also we show that for a critical drain-source voltage a negative resistance is seen at current-voltage curve of 1 × 1 nm2 sample because of electron-electron interaction, and in consequence it can tolerate lower gate voltage in real practical applications.

  1. Pseudogap in the Eliashberg approach based on electron-phonon and electron-electron-phonon interaction

    Energy Technology Data Exchange (ETDEWEB)

    Szczesniak, R. [Institute of Physics, Czestochowa University of Technology (Poland); Institute of Physics, Jan Dlugosz University in Czestochowa (Poland); Durajski, A.P.; Duda, A.M. [Institute of Physics, Czestochowa University of Technology (Poland)

    2017-04-15

    The properties of the superconducting and the anomalous normal state were described by using the Eliashberg method. The pairing mechanism was reproduced with the help of the Hamiltonian, which models the electron-phonon and the electron-electron-phonon interaction (EEPh). The set of the Eliashberg equations, which determines the order parameter function (φ), the wave function renormalization factor (Z), and the energy shift function (χ), was derived. It was proven that for the sufficiently large values of the EEPh potential, the doping dependence of the order parameter (φ/Z) has the analogous course to that observed experimentally in cuprates. The energy gap in the electron density of states is induced by Z and χ - the contribution from φ is negligible. The electron density of states possesses the characteristic asymmetric form and the pseudogap is observed above the critical temperature. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Panoramic stereo sphere vision

    Science.gov (United States)

    Feng, Weijia; Zhang, Baofeng; Röning, Juha; Zong, Xiaoning; Yi, Tian

    2013-01-01

    Conventional stereo vision systems have a small field of view (FOV) which limits their usefulness for certain applications. While panorama vision is able to "see" in all directions of the observation space, scene depth information is missed because of the mapping from 3D reference coordinates to 2D panoramic image. In this paper, we present an innovative vision system which builds by a special combined fish-eye lenses module, and is capable of producing 3D coordinate information from the whole global observation space and acquiring no blind area 360°×360° panoramic image simultaneously just using single vision equipment with one time static shooting. It is called Panoramic Stereo Sphere Vision (PSSV). We proposed the geometric model, mathematic model and parameters calibration method in this paper. Specifically, video surveillance, robotic autonomous navigation, virtual reality, driving assistance, multiple maneuvering target tracking, automatic mapping of environments and attitude estimation are some of the applications which will benefit from PSSV.

  3. The STEREO Mission

    CERN Document Server

    2008-01-01

    The STEREO mission uses twin heliospheric orbiters to track solar disturbances from their initiation to 1 AU. This book documents the mission, its objectives, the spacecraft that execute it and the instruments that provide the measurements, both remote sensing and in situ. This mission promises to unlock many of the mysteries of how the Sun produces what has become to be known as space weather.

  4. Usability of car stereo.

    Science.gov (United States)

    Razza, Bruno Montanari; Paschoarelli, Luis Carlos

    2012-01-01

    Automotive sound systems vary widely in terms of functions and way of use between different brands and models what can bring difficulties and lack of consistency to the user. This study aimed to analyze the usability of car stereo commonly found in the market. Four products were analyzed by task analysis and after use reports and the results indicate serious usability issues with respect to the form of operation, organization, clarity and quality of information, visibility and readability, among others.

  5. System for clinical photometric stereo endoscopy

    Science.gov (United States)

    Durr, Nicholas J.; González, Germán.; Lim, Daryl; Traverso, Giovanni; Nishioka, Norman S.; Vakoc, Benjamin J.; Parot, Vicente

    2014-02-01

    Photometric stereo endoscopy is a technique that captures information about the high-spatial-frequency topography of the field of view simultaneously with a conventional color image. Here we describe a system that will enable photometric stereo endoscopy to be clinically evaluated in the large intestine of human patients. The clinical photometric stereo endoscopy system consists of a commercial gastroscope, a commercial video processor, an image capturing and processing unit, custom synchronization electronics, white light LEDs, a set of four fibers with diffusing tips, and an alignment cap. The custom pieces that come into contact with the patient are composed of biocompatible materials that can be sterilized before use. The components can then be assembled in the endoscopy suite before use. The resulting endoscope has the same outer diameter as a conventional colonoscope (14 mm), plugs into a commercial video processor, captures topography and color images at 15 Hz, and displays the conventional color image to the gastroenterologist in real-time. We show that this system can capture a color and topographical video in a tubular colon phantom, demonstrating robustness to complex geometries and motion. The reported system is suitable for in vivo evaluation of photometric stereo endoscopy in the human large intestine.

  6. Kinder, gentler stereo

    Science.gov (United States)

    Siegel, Mel; Tobinaga, Yoshikazu; Akiya, Takeo

    1999-05-01

    Not only binocular perspective disparity, but also many secondary binocular and monocular sensory phenomena, contribute to the human sensation of depth. Binocular perspective disparity is notable as the strongest depth perception factor. However means for creating if artificially from flat image pairs are notorious for inducing physical and mental stresses, e.g., 'virtual reality sickness'. Aiming to deliver a less stressful 'kinder gentler stereo (KGS)', we systematically examine the secondary phenomena and their synergistic combination with each other and with binocular perspective disparity. By KGS we mean a stereo capture, rendering, and display paradigm without cue conflicts, without eyewear, without viewing zones, with negligible 'lock-in' time to perceive the image in depth, and with a normal appearance for stereo-deficient viewers. To achieve KGS we employ optical and digital image processing steps that introduce distortions contrary to strict 'geometrical correctness' of binocular perspective but which nevertheless result in increased stereoscopic viewing comfort. We particularly exploit the lower limits of interoccular separation, showing that unexpectedly small disparities stimulate accurate and pleasant depth sensations. Under these circumstances crosstalk is perceived as depth-of-focus rather than as ghosting. This suggests the possibility of radically new approaches to stereoview multiplexing that enable zoneless autostereoscopic display.

  7. Method for Stereo Mapping Based on Objectarx and Pipeline Technology

    Science.gov (United States)

    Liu, F.; Chen, T.; Lin, Z.; Yang, Y.

    2012-07-01

    Stereo mapping is an important way to acquire 4D production. Based on the development of the stereo mapping and the characteristics of ObjectARX and pipeline technology, a new stereo mapping scheme which can realize the interaction between the AutoCAD and digital photogrammetry system is offered by ObjectARX and pipeline technology. An experiment is made in order to make sure the feasibility with the example of the software MAP-AT (Modern Aerial Photogrammetry Automatic Triangulation), the experimental results show that this scheme is feasible and it has very important meaning for the realization of the acquisition and edit integration.

  8. 体感设备与被动立体相结合的人机交互方法研究%Research on the method of human-computer interaction in combining somatosensory equipment with passive stereo

    Institute of Scientific and Technical Information of China (English)

    谭剑波; 张光刘; 李琳

    2011-01-01

    The technology of human-computer interaction full of sense of immersion and manipulation is the target of researchers in the area of virtual reality, and three-dimensional display and somatosensory interaction has become the hot topics at present. By means of introducing the Somatosensory equipment into the display environment of passive stereo, this paper designs and develops a three-dimensional tennis game. Taking the advantage of a stereo display of 3D, and through reasonably planning the relationships and mapping links among objects, participants' visual sense and somatosensory equipment in the game, the sense of immersion and manipulation is improved dramatically.%富有沉浸感和操纵感的人机交互技术是虚拟现实学科研究者的追求目标,立体显示与体感交互是当前的热点问题.文章将体感设备引入被动立体的显示环境,设计开发了一个立体网球游戏,利用立体显示的三维视觉特性,通过合理规划游戏中的对象、参与人的视觉感官以及体感设备三者之间的联系和映射关系,使沉浸感和操纵感得到很大的提升.

  9. Electron-electron interactions in graphene field-induced quantum dots in a high magnetic field

    DEFF Research Database (Denmark)

    Orlof, A.; Shylau, Artsem; Zozoulenko, I. V.

    2015-01-01

    We study the effect of electron-electron interaction in graphene quantum dots defined by an external electrostatic potential and a high magnetic field. To account for the electron-electron interaction, we use the Thomas-Fermi approximation and find that electron screening causes the formation...... of compressible strips in the potential profile and the electron density. We numerically solve the Dirac equations describing the electron dynamics in quantum dots, and we demonstrate that compressible strips lead to the appearance of plateaus in the electron energies as a function of the magnetic field. Finally...

  10. Quantum electron self-interaction in a strong laser field

    CERN Document Server

    Meuren, S

    2011-01-01

    The quantum state of an electron in a strong laser field is altered if the interaction of the electron with its own electromagnetic field is taken into account. Starting from the Schwinger-Dirac equation, we determine the states of an electron in a plane-wave field with inclusion, at leading order, of its electromagnetic self-interaction. On the one hand, the electron states show a pure "quantum" contribution to the electron quasi-momentum, conceptually different from the conventional "classical" one arising from the quiver motion of the electron. On the other hand, the electron self-interaction induces a distinct dynamics of the electron spin, whose effects are shown to be measurable in principle with available technology.

  11. Modeling microwave/electron-cloud interaction

    CERN Document Server

    Mattes, M; Zimmermann, F

    2013-01-01

    Starting from the separate codes BI-RME and ECLOUD or PyECLOUD, we are developing a novel joint simulation tool, which models the combined effect of a charged particle beam and of microwaves on an electron cloud. Possible applications include the degradation of microwave transmission in tele-communication satellites by electron clouds; the microwave-transmission tecchniques being used in particle accelerators for the purpose of electroncloud diagnostics; the microwave emission by the electron cloud itself in the presence of a magnetic field; and the possible suppression of electron-cloud formation in an accelerator by injecting microwaves of suitable amplitude and frequency. A few early simulation results are presented.

  12. IMPACT: Science Goals and Firsts with STEREO

    Science.gov (United States)

    Luhmann, J.; Curtis, D.; Impact Team

    STEREO's IMPACT (In-situ Measurements of Particles and CME Transients) investigation provides the first opportunity for long duration, detailed observations of 1 AU magnetic field structures, plasma and suprathermal electrons, and energetic particles at points bracketing Earth's heliospheric location. The PLASTIC instrument, described in a companion presentation, will make plasma ion composition measurements completing STEREO's comprehensive in-situ perspective. Stereoscopic/3D information from the STEREO SECCHI imagers and SWAVES radio experiment, also described in this session, will make it possible to use both multipoint and quadrature studies to connect interplanetary Coronal Mass Ejections (ICME) and solar wind structures to CMEs and coronal holes observed at the Sun. IMPACT is also expected to test the patterns of solar energetic particle (SEP) events inferred from earlier statistical studies and multipoint measurements, and to resolve outstanding questions of source location(s) and seed populations with combinations of SEP composition measurements and other IMPACT and STEREO observations. Additional important insight will result from ongoing L1 viewpoint imaging and in-situ measurements from SOHO, WIND and ACE. In the late 1970s and early 1980s the Helios twin spacecraft mission obtained paired plasma, field and SEP in-situ data sets complemented by the Solwind and Solar Maximum Mission (SMM) coronagraph images of CMEs, and near-Earth in-situ data from IMP-8 and ISEE-3. IMPACT's updated instruments and modern data processing, transmitting, and analysis capabilities, with support from the other STEREO investigations and today's realistic 3D models of the corona, solar wind and CMEs, will prove or in some cases revolutionize the observational paradigms gleaned in the era of the Helios/Solwind/SMM/IMP-8/ISEE3 spacecraft combinations. The resulting views of in-situ space weather will without doubt leave us with a forever transformed perspective of L1

  13. Convergent Flows: Humanities Scholars and Their Interactions with Electronic Texts

    Science.gov (United States)

    Sukovic, Suzana

    2008-01-01

    This article reports research findings related to converging formats, media, practices, and ideas in the process of academics' interaction with electronic texts during a research project. The findings are part of the results of a study that explored interactions of scholars in literary and historical studies with electronic texts as primary…

  14. Interaction of electrons with light metal hydrides in the transmission electron microscope.

    Science.gov (United States)

    Wang, Yongming; Wakasugi, Takenobu; Isobe, Shigehito; Hashimoto, Naoyuki; Ohnuki, Somei

    2014-12-01

    Transmission electron microscope (TEM) observation of light metal hydrides is complicated by the instability of these materials under electron irradiation. In this study, the electron kinetic energy dependences of the interactions of incident electrons with lithium, sodium and magnesium hydrides, as well as the constituting element effect on the interactions, were theoretically discussed, and electron irradiation damage to these hydrides was examined using in situ TEM. The results indicate that high incident electron kinetic energy helps alleviate the irradiation damage resulting from inelastic or elastic scattering of the incident electrons in the TEM. Therefore, observations and characterizations of these materials would benefit from increased, instead decreased, TEM operating voltage.

  15. Electron dynamics controlled via self-interaction

    CERN Document Server

    Tamburini, Matteo; Di Piazza, Antonino

    2013-01-01

    The dynamics of an electron in a strong laser field can be significantly altered by radiation reaction. This usually results in a strongly damped motion, with the electron losing a large fraction of its initial energy. Here we show that the electron dynamics in a bichromatic laser pulse can be indirectly controlled by a comparatively small radiation reaction force through its interplay with the Lorentz force. By changing the relative phase between the two frequency components of the bichromatic laser field, an ultrarelativistic electron bunch colliding head-on with the laser pulse can be deflected in a controlled way, with the deflection angle being independent of the initial electron energy. The effect is predicted to be observable with intensities available at upcoming laser facilities.

  16. Hearing symptoms personal stereos

    Science.gov (United States)

    da Luz, Tiara Santos; Borja, Ana Lúcia Vieira de Freitas

    2012-01-01

    Summary Introduction: Practical and portable the personal stereos if had become almost indispensable accessories in the day the day. Studies disclose that the portable players of music can cause auditory damages in the long run for who hear music in high volume for a drawn out time. Objective: to verify the prevalence of auditory symptoms in users of amplified players and to know its habits of use Method: Observational prospective study of transversal cut carried through in three institutions of education of the city of Salvador BA, being two of public net and one of the private net. 400 students had answered to the questionnaire, of both the sex, between 14 and 30 years that had related the habit to use personal stereos. Results: The symptoms most prevalent had been hyperacusis (43.5%), auricular fullness (30.5%) and humming (27.5), being that the humming is the symptom most present in the population youngest. How much to the daily habits: 62.3% frequent use, 57% in raised intensities, 34% in drawn out periods. An inverse relation between exposition time was verified and the band of age (p = 0,000) and direct with the prevalence of the humming. Conclusion: Although to admit to have knowledge on the damages that the exposition the sound of high intensity can cause the hearing, the daily habits of the young evidence the inadequate use of the portable stereos characterized by long periods of exposition, raised intensities, frequent use and preference for the insertion phones. The high prevalence of symptoms after the use suggests a bigger risk for the hearing of these young. PMID:25991931

  17. Hearing symptoms personal stereos

    Directory of Open Access Journals (Sweden)

    Tiara Santos da Luz1

    2012-01-01

    Full Text Available Introduction: Practical and portable the personal stereos if had become almost indispensable accessories in the day the day. Studies disclose that the portable players of music can cause auditory damages in the long run for who hear music in high volume for a drawn out time. Objective: to verify the prevalence of auditory symptoms in users of amplified players and to know its habits of use. Method: Observational prospective study of transversal cut carried through in three institutions of education of the city of Salvador BA, being two of public net and one of the private net. 400 students had answered to the questionnaire, of both the sex, between 14 and 30 years that had related the habit to use personal stereos. Results: The symptoms most prevalent had been hyperacusis (43.5%, auricular fullness (30.5% and humming (27.5, being that the humming is the symptom most present in the population youngest. How much to the daily habits: 62.3% frequent use, 57% in raised intensities, 34% in drawn out periods. An inverse relation between exposition time was verified and the band of age (p=0,000 and direct with the prevalence of the humming. Conclusion: Although to admit to have knowledge on the damages that the exposition the sound of high intensity can cause the hearing, the daily habits of the young evidence the inadequate use of the portable stereos characterized by long periods of exposition, raised intensities, frequent use and preference for the insertion phones. The high prevalence of symptoms after the use suggests a bigger risk for the hearing of these young.

  18. STEREO interplanetary shocks and foreshocks

    Energy Technology Data Exchange (ETDEWEB)

    Blanco-Cano, X. [Instituto de Geofisica, UNAM, CU, Coyoacan 04510 DF (Mexico); Kajdic, P. [IRAP-University of Toulouse, CNRS, Toulouse (France); Aguilar-Rodriguez, E. [Instituto de Geofisica, UNAM, Morelia (Mexico); Russell, C. T. [ESS and IGPP, University of California, Los Angeles, 603 Charles Young Drive, Los Angeles, CA 90095 (United States); Jian, L. K. [NASA Goddard Space Flight Center, Greenbelt, MD and University of Maryland, College Park, MD (United States); Luhmann, J. G. [SSL, University of California Berkeley (United States)

    2013-06-13

    We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and {theta}{sub Bn}{approx}20-86 Degree-Sign . We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr {<=}0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at {approx}1 AU and have been producing suprathermal particles for a shorter time.

  19. Stereo-panoramic Data

    KAUST Repository

    Cutchin, Steve

    2013-03-07

    Systems and methods for automatically generating three-dimensional panoramic images for use in various virtual reality settings are disclosed. One embodiment of the system includes a stereo camera capture device (SCD), a programmable camera controller (PCC) that rotates, orients, and controls the SCD, a robotic maneuvering platform (RMP), and a path and adaptation controller (PAC). In that embodiment, the PAC determines the movement of the system based on an original desired path and input gathered from the SCD during an image capture process.

  20. Interactivity in an Electronically Delivered Marketing Course.

    Science.gov (United States)

    Larson, Paul D.

    2002-01-01

    In a marketing course delivered using Lotus Notes, 32 students were randomly assigned to large or small groups with heavy or light coaching. No differences in interactivity appeared related to group size or gender. More coaching increased the quantity, not quality, of interactivity. Quality seemed to decrease as quantity increased. (Contains 35…

  1. Generation of surface electrons in femtosecond laser-solid interactions

    Institute of Scientific and Technical Information of China (English)

    XU; Miaohua; LI; Yutong; YUAN; Xiaohui; ZHENG; Zhiyuan; LIANG; Wenxi; YU; Quanzhi; ZHANG; Yi; WANG; Zhaohua; WEI; Zhiyi; ZHANG; Jie

    2006-01-01

    The characteristics of hot electrons produced by p-polarized femtosecond laser-solid interactions are studied. The experimental results show that the outgoing electrons are mainly emitted in three directions: along the target surface, the normal direction and the laser backward direction. The electrons flowing along the target surface are due to the confinement of the electrostatic field and the surface magnetic field, while the electrons in the normal direction due to the resonant absorption.

  2. Writing an Electronic Astronomy Book with Interactive Curricular Material

    Science.gov (United States)

    Thompson, Kristen L.; Belloni, Mario; Christian, Wolfgang

    2015-01-01

    With the rise of tablets, the past few years have seen an increase in the demand for quality electronic textbooks. Unfortunately, most of the current offerings do not exploit the accessibility and interactivity that electronic books can deliver. In this poster, we discuss how we are merging our curriculum development projects (Physlets, Easy Java/JavaScript Simulations, and Open Source Physics) with the EPUB electronic book format to develop an interactive textbook for use in a one-semester introductory astronomy course. The book, Astronomy: An Interactive Introduction, combines the narrative, equations, and images of a traditional astronomy text with new JavaScript simulations.

  3. Sex differences in perceived outcomes of electronic mail interactions.

    Science.gov (United States)

    Harper, Vernon B

    2002-04-01

    Researchers have found that sex plays a crucial role in perceptions of usability, graphical accents, and general satisfaction within computer-mediated interactions. 192 students (71 men and 121 women) responded to 12 items taken from the Electronic Mail Outcome Scale related to their perceived Appropriateness, Effectiveness, and Satisfaction obtained through electronic mail interactions. Analysis indicated no significant differences between men and women in reference to either Effectiveness or Satisfaction; however, women were more sensitive to social expectations within electronic mail interactions than men.

  4. RKKY interaction for the spin-polarized electron gas

    Science.gov (United States)

    Valizadeh, Mohammad M.; Satpathy, Sashi

    2015-11-01

    We extend the original work of Ruderman, Kittel, Kasuya and Yosida (RKKY) on the interaction between two magnetic moments embedded in an electron gas to the case where the electron gas is spin-polarized. The broken symmetry of a host material introduces the Dzyaloshinsky-Moriya (DM) vector and tensor interaction terms, in addition to the standard RKKY term, so that the net interaction energy has the form ℋ = JS1 ṡS2 + D ṡS1 ×S2 + S1 ṡΓ ↔ṡS2. We find that for the spin-polarized electron gas, a nonzero tensor interaction Γ ↔ is present in addition to the scalar RKKY interaction J, while D is zero due to the presence of inversion symmetry. Explicit expressions for these are derived for the electron gas both in 2D and 3D and we show that the net magnetic interaction can be expressed as a sum of Heisenberg and Ising like terms. The RKKY interaction exhibits a beating pattern, caused by the presence of the two Fermi momenta kF↑ and kF↓, while the R-3 distance dependence of the original RKKY result for the 3D electron gas is retained. This model serves as a simple example of the magnetic interaction in systems with broken symmetry, which goes beyond the RKKY interaction.

  5. Light propagation and interaction observed with electrons.

    Science.gov (United States)

    Word, Robert C; Fitzgerald, J P S; Könenkamp, R

    2016-01-01

    We discuss possibilities for a microscopic optical characterization of thin films and surfaces based on photoemission electron microscopy. We show that propagating light with wavelengths across the visible range can readily be visualized, and linear and non-linear materials properties can be evaluated non-invasively with nanometer spatial resolution. While femtosecond temporal resolution can be achieved in pump-probe-type experiments, the interferometric approach presented here has typical image frame times of ~200 fs.

  6. Interactive Technologies in Electronic Educational Resources

    Science.gov (United States)

    Anisimova, Tatyana Ivanovna; Krasnova, Lyubov Alekseevna

    2015-01-01

    Modern professional education in the transition to a tiered system of specialists training is focused not on the transfer of ready knowledge but on teaching to find this knowledge and to apply them in situations close to the professional conditions. The educational process, relying on use of interactive methods of teaching, which is organized with…

  7. Electron-Electron and Electron-Phonon interactions effects on the tunnel electronic spectrum of PbS quantum dots

    Science.gov (United States)

    Wang, Hongyue; Lhuillier, Emmanuel; Yu, Qian; Mottaghizadeh, Alireza; Ulysse, Christian; Zimmers, Alexandre; Dubertret, Benoit; Aubin, Herve

    2015-03-01

    We present a tunnel spectroscopy study of the electronic spectrum of single PbS Quantum Dots (QDs) trapped between nanometer-spaced electrodes, measured at low temperature T=5 K. The carrier filling of the QD can be controlled either by the drain voltage in the shell filling regime or by a gate voltage. In the empty QD, the tunnel spectrum presents the expected signature of the 8x degenerated excited levels. In the drain controlled shell filling regime, the levels degeneracies are lifted by the global electrostatic Coulomb energy of the QD; in the gate controlled shell filling regime, the levels degeneracies are lifted by the intra-Coulomb interactions. In the charged quantum dot, electron-phonons interactions lead to the apparition of Franck-Condon side bands on the single excited levels and possibly Franck Condon blockade at low energy. The sharpening of excited levels at higher gate voltage suggests that the magnitude of electron-phonon interactions is decreased upon increasing the electron filling in the quantum dot. This work was supported by the French ANR Grants 10-BLAN-0409-01, 09-BLAN-0388-01, by the Region Ile-de-France in the framework of DIM Nano-K and by China Scholarship Council.

  8. Deblocking of mobile stereo video

    Science.gov (United States)

    Azzari, Lucio; Gotchev, Atanas; Egiazarian, Karen

    2012-02-01

    Most of candidate methods for compression of mobile stereo video apply block-transform based compression based on the H-264 standard with quantization of transform coefficients driven by quantization parameter (QP). The compression ratio and the resulting bit rate are directly determined by the QP level and high compression is achieved for the price of visually noticeable blocking artifacts. Previous studies on perceived quality of mobile stereo video have revealed that blocking artifacts are the most annoying and most influential in the acceptance/rejection of mobile stereo video and can even completely cancel the 3D effect and the corresponding quality added value. In this work, we address the problem of deblocking of mobile stereo video. We modify a powerful non-local transform-domain collaborative filtering method originally developed for denoising of images and video. The method employs grouping of similar block patches residing in spatial and temporal vicinity of a reference block in filtering them collaboratively in a suitable transform domain. We study the most suitable way of finding similar patches in both channels of stereo video and suggest a hybrid four-dimensional transform to process the collected synchronized (stereo) volumes of grouped blocks. The results benefit from the additional correlation available between the left and right channel of the stereo video. Furthermore, addition sharpening is applied through an embedded alpha-rooting in transform domain, which improve the visual appearance of the deblocked frames.

  9. The Electron-Phonon Interaction as Studied by Photoelectron Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    D.W. Lynch

    2004-09-30

    With recent advances in energy and angle resolution, the effects of electron-phonon interactions are manifest in many valence-band photoelectron spectra (PES) for states near the Fermi level in metals.

  10. DIFFERENCES BETWEEN ELECTRONS AND POSITRONS INTERACTING WITH DETECTOR MATERIAL

    NARCIS (Netherlands)

    MEIRING, WJ; VANKLINKEN, J; WICHERS, VA

    1991-01-01

    A theory of multiple scattering, exhibiting differences between electrons and positrons in interactions with matter, is developed. Additional differences in stopping power and annihilation for positrons are briefly discussed. Experimental verification of these differences is reported for plastic sci

  11. Design and Implementation of Equipment Interactive Electronic Technical Manuals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Interactive electronic technical manuals (IETMs) can significantly improve the maintenance and logistics of modern weapon equipment. Main functiors and development strategies of IETMs are discussed. As an example, the IETM development of a certain equipment is demonstrated.

  12. On the Cauchy Problem Describing an Electron-Phonon Interaction

    Institute of Scientific and Technical Information of China (English)

    Jo(a)o-Paulo DIAS; Mário FIGUEIRA; Filipe OLIVEIRA

    2011-01-01

    In this paper, a model is derived to describe a quartic anharmonic interatomic interaction with an external potential involving a pair electron-phonon. The authors study the corresponding Cauchy Problem in the semilinear and quasilinear cases.

  13. Low Energy X-Ray and Electron Interactions within Matter.

    Science.gov (United States)

    1980-03-01

    Microscopy at Pomona College," Norelco Reporter, VII, 137 (1960). b."Isolation of Selected Elements with an Electron Microscope ," Norelco Reporter...38. "Measurement of Primary Electron Interaction Coefficients (500 to 1500 eV Region," Colloque International du C.N.R.S., Processus Electroniques

  14. Interacting electrons theory and computational approaches

    CERN Document Server

    Martin, Richard M; Ceperley, David M

    2016-01-01

    Recent progress in the theory and computation of electronic structure is bringing an unprecedented level of capability for research. Many-body methods are becoming essential tools vital for quantitative calculations and understanding materials phenomena in physics, chemistry, materials science and other fields. This book provides a unified exposition of the most-used tools: many-body perturbation theory, dynamical mean field theory and quantum Monte Carlo simulations. Each topic is introduced with a less technical overview for a broad readership, followed by in-depth descriptions and mathematical formulation. Practical guidelines, illustrations and exercises are chosen to enable readers to appreciate the complementary approaches, their relationships, and the advantages and disadvantages of each method. This book is designed for graduate students and researchers who want to use and understand these advanced computational tools, get a broad overview, and acquire a basis for participating in new developments.

  15. Modelling low energy electron interactions for biomedical uses of radiation

    Energy Technology Data Exchange (ETDEWEB)

    Fuss, M; Garcia, G [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones CientIficas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Munoz, A; Oller, J C [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avenida Complutense 22, 28040 Madrid (Spain); Blanco, F [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, Avenida Complutense s.n., 28040 Madrid (Spain); Limao-Vieira, P [Departamento de Fisica, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Huerga, C; Tellez, M [Hospital Universitario La Paz, paseo de la Castellana 261, 28046 Madrid (Spain); Hubin-Fraskin, M J [Department of Chemistry, University of Liege, 4000 Liege 1 (Belgium); Nixon, K; Brunger, M, E-mail: g.garcia@imaff.cfmac.csic.e [School of Chemistry, Physics and Earth Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia)

    2009-11-15

    Current radiation based medical applications in the field of radiotherapy, radio-diagnostic and radiation protection require modelling single particle interactions at the molecular level. Due to their relevance in radiation damage to biological systems, special attention should be paid to include the effect of low energy secondary electrons. In this study we present a single track simulation procedure for photons and electrons which is based on reliable experimental and theoretical cross section data and the energy loss distribution functions derived from our experiments. The effect of including secondary electron interactions in this model will be discussed.

  16. Research on stereo vision odometry

    Science.gov (United States)

    Zhang, Xiaoling; Zhang, Baofeng; Tian, Xiuzhen

    2010-11-01

    The stereo visual odometer in vision based on the navigation system is proposed in the paper. The stereo visual odometer can obtain the motion data to implement the position and attitude estimation of ALV(Autonomous Land Vehicle). Two key technology in the stereo vision odometer are dissertated. The first is using SIFT(Scale Invariant Feature Transform) to extract suitable feature, match points pairs in the feature, and track the feature of fore and after frames of the same point on the object. The second is using matching and tracking to obtain the different 3-D coordinate of the feature of the point on the object, and to compute the motion parameters by motion estimate. The unknown outdoor environment is adopted in the experiment. The results show that the stereo vision odometer is more accurate, and the measurement error dose not increase with the movement distance increasing. It can be used as an important supplement of conventional odometer.

  17. Transport phenomena in disordered interacting electron systems

    Science.gov (United States)

    Michaeli, Karen

    We develop a user friendly scheme based on the quantum kinetic equation for studying electric and thermal transport phenomena in the presence of interactions and disorder. We demonstrate that this scheme is suitable for both a systematic perturbative calculation as well as a general analysis. The work was motivated by the growing number of experiments of thermal and thermoelectric transport, and the absence of adequate theoretical tools for studying them. In particular, for thermal transport, the widely used Kubo formula is rather cumbersome. In this thesis, we present a systematic derivation of the quantum kinetic approach which we believe can be a good alternative to the Kubo formula. One main advantage of the kinetic approach is that it provides us with an intuitive picture for both electric and thermal transport. The strength of our scheme is in its generality that allow us to apply it for different kinds of interactions. We study the effect of the superconducting fluctuations on the Hall and Nernst effects. We show that the strong Nernst effect observed recently in amorphous superconducting films far above the critical temperature is caused by the fluctuations of the superconducting order parameter. We demonstrate that in the limit T → 0 the contribution of the magnetization ensures the vanishing of the Nernst signal in accordance with the third law of thermodynamics. We obtained a striking agreement between our theoretical calculations and the experimental data in a broad region of temperatures and magnetic fields. In addition, we present the calculation of the Hall conductivity in the vicinity of the superconducting transition driven by a magnetic field. We discuss the peculiar feature of both the Hall coefficient and Nernst signal anticipated near the quantum phase transition.

  18. Low Cost Interactive Electronic Whiteboard Using Nintendo Wii Remote

    OpenAIRE

    2010-01-01

    Problem statement: The application of interactive whiteboard offers extensive benefits in the learning and teaching process for classroom environment. The high cost associated with commercial interactive whiteboard may hinder its application in primary or secondary school, especially in developing countries. Thus, this study describes the methods used to create a low cost interactive and viable electronic whiteboard by using the capabilities of the Nintendo Wiimotes. It also looks at the poss...

  19. Spin Relaxation in GaAs: Importance of Electron-Electron Interactions

    Directory of Open Access Journals (Sweden)

    Gionni Marchetti

    2014-04-01

    Full Text Available We study spin relaxation in n-type bulk GaAs, due to the Dyakonov–Perel mechanism, using ensemble Monte Carlo methods. Our results confirm that spin relaxation time increases with the electronic density in the regime of moderate electronic concentrations and high temperature. We show that the electron-electron scattering in the non-degenerate regime significantly slows down spin relaxation. This result supports predictions by Glazov and Ivchenko. Most importantly, our findings highlight the importance of many-body interactions for spin dynamics: we show that only by properly taking into account electron-electron interactions within the simulations, results for the spin relaxation time—with respect to both electron density and temperature—will reach good quantitative agreement with corresponding experimental data. Our calculations contain no fitting parameters.

  20. Generation of anomalously energetic suprathermal electrons by an electron beam interacting with a nonuniform plasma

    CERN Document Server

    Sydorenko, D; Chen, L; Ventzek, P L G

    2015-01-01

    Generation of anomalously energetic suprathermal electrons was observed in simulation of a high- voltage dc discharge with electron emission from the cathode. An electron beam produced by the emission interacts with the nonuniform plasma in the discharge via a two-stream instability. Efficient energy transfer from the beam to the plasma electrons is ensured by the plasma nonuniformity. The electron beam excites plasma waves whose wavelength and phase speed gradually decrease towards anode. The short waves near the anode accelerate plasma bulk electrons to suprathermal energies. The sheath near the anode reflects some of the accelerated electrons back into the plasma. These electrons travel through the plasma, reflect near the cathode, and enter the accelerating area again but with a higher energy than before. Such particles are accelerated to energies much higher than after the first acceleration. This mechanism plays a role in explaining earlier experimental observations of energetic suprathermal electrons i...

  1. Photometric stereo endoscopy

    Science.gov (United States)

    Parot, Vicente; Lim, Daryl; González, Germán; Traverso, Giovanni; Nishioka, Norman S.; Vakoc, Benjamin J.

    2013-01-01

    Abstract. While color video endoscopy has enabled wide-field examination of the gastrointestinal tract, it often misses or incorrectly classifies lesions. Many of these missed lesions exhibit characteristic three-dimensional surface topographies. An endoscopic system that adds topographical measurements to conventional color imagery could therefore increase lesion detection and improve classification accuracy. We introduce photometric stereo endoscopy (PSE), a technique which allows high spatial frequency components of surface topography to be acquired simultaneously with conventional two-dimensional color imagery. We implement this technique in an endoscopic form factor and demonstrate that it can acquire the topography of small features with complex geometries and heterogeneous optical properties. PSE imaging of ex vivo human gastrointestinal tissue shows that surface topography measurements enable differentiation of abnormal shapes from surrounding normal tissue. Together, these results confirm that the topographical measurements can be obtained with relatively simple hardware in an endoscopic form factor, and suggest the potential of PSE to improve lesion detection and classification in gastrointestinal imaging. PMID:23864015

  2. Local Surface Reconstruction from MER images using Stereo Workstation

    Science.gov (United States)

    Shin, Dongjoe; Muller, Jan-Peter

    2010-05-01

    -HRSC reconstruction workflow. This algorithm's performance is reasonable even for close-range imagery so long as the stereo -pair does not too large a baseline displacement. For post-processing, a Bundle Adjustment (BA) is used to optimise the initial calibration parameters, which bootstrap the reconstruction results. Amongst many options for the non-linear optimisation, the LMA has been adopted due to its stability so that the BA searches the best calibration parameters whilst iteratively minimising the re-projection errors of the initial reconstruction points. For the evaluation of the proposed method, the result of the method is compared with the reconstruction from a disparity map provided by JPL using their operational processing system. Visual and quantitative comparison will be presented as well as updated camera parameters. As part of future work, we will investigate a method expediting the processing speed of the stereo region growing process and look into the possibility of extending the use of the stereo workstation to orbital image processing. Such an interactive stereo workstation can also be used to digitize points and line features as well as assess the accuracy of stereo processed results produced from other stereo matching algorithms available from within the consortium and elsewhere. It can also provide "ground truth" when suitably refined for stereo matching algorithms as well as provide visual cues as to why these matching algorithms sometimes fail to mitigate this in the future. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 218814 "PRoVisG".

  3. Electronic Density Approaches to the Energetics of Noncovalent Interactions

    Directory of Open Access Journals (Sweden)

    Peter Politzer

    2004-04-01

    Full Text Available Abstract: We present an overview of procedures that have been developed to compute several energetic quantities associated with noncovalent interactions. These formulations involve numerical integration over appropriate electronic densities. Our focus is upon the electrostatic interaction between two unperturbed molecules, the effect of the polarization of each charge distribution by the other, and the total energy of interaction. The expression for the latter is based upon the Hellmann-Feynman theorem. Applications to a number of systems are discussed; among them are dimers of uracil and interacting pairs of molecules in the crystal lattice of the energetic compound RDX.

  4. Probing Nanoscale Electronic and Magnetic Interaction with Scanning Tunneling Spectroscopy

    DEFF Research Database (Denmark)

    Bork, Jakob

    This thesis is concerned with fundamental research into electronic and magnetic interaction on the nanoscale. From small metallic and magnetic islands and layers to single atoms. The research revolves around magnetic interaction probed through the spectroscopic capabilities of the scanning....... This is related to research in correlated electron materials such as studies of phase transitions in heavy fermion compounds and magnetic interaction in spintronic research. The capping of cobalt islands on Cu(111) with silver is investigated with STM and photoemission spectroscopy. It is shown that at low...... coverage the silver preferably nucleates on top of the bilayer high cobalt islands compared to directly on the Cu(111) substrate. Furthermore, the silver forms a combination of a reconstruction and a Moire pattern which is investigated with low-energy electron diraction and spectroscopic STM mapping at 6...

  5. Magneto-Coulomb Drag: Interplay of Electron-Electron Interactions and Landau Quantization

    DEFF Research Database (Denmark)

    Bønsager, Martin Christian; Flensberg, Karsten; Hu, Ben Yu-Kuang

    1996-01-01

    effect. The presence of both electron-electron interactions and Landau quantization results in (i) a twin-peaked structure of rho(21)(B) in the interplateau regions at low temperatures and (ii) for the chemical potential at the center of a Landau level band, a peaked temperature dependence of rho(21)(T...

  6. Scanning tunneling spectroscopy on electron-boson interactions in superconductors

    CERN Document Server

    Schackert, Michael Peter

    2015-01-01

    This work describes the experimental study of electron-boson interactions in superconductors by means of inelastic electron tunneling spectroscopy performed with a scanning tunneling microscope (STM) at temperatures below 1 K. This new approach allows the direct measurement of the Eliashberg function of conventional superconductors as demonstrated on lead (Pb) and niobium (Nb). Preparative experiments on unconventional iron-pnictides are presented in the end.

  7. High Harmonic Inverse Free Electron Laser Interaction at 800 nm

    Energy Technology Data Exchange (ETDEWEB)

    Sears, C

    2005-03-08

    We demonstrate for the first time an inverse free electron laser (IFEL) operating at 800 nm and observe multiple resonances of the IFEL interaction. The IFEL is tested at half its fundamental resonance electron energy and scanned through multiple harmonics by adjusting the undulator field strength. We obtain a peak modulation of {approx}50 keV FWHM and observe the 4th through 6th harmonics of the IFEL resonance.

  8. Evaluation of electron-electron interactions in coupled quantum dots by using far-infrared spectra

    Institute of Scientific and Technical Information of China (English)

    Dong Qing-Rui

    2008-01-01

    We have studied the far-infrared spectra of two-electron vertically coupled quantum dots in an axial magnetic field by exact diagonalization. The calculated results show an obvious difference in role between the interactions for spin S = 1 and for spin S = 0. The results support the possibility to evaluate the interactions by far-infrared spectroscopy in vertically coupled quantum dots.

  9. Optical Conductivity of Graphene Sheet Including Electron-Phonon Interaction

    Institute of Scientific and Technical Information of China (English)

    Hamze Mousavi

    2012-01-01

    Using an expression of optical conductivity, based on the linear response theory, the Green's function technique and within the Holstein Hamiltonian model, the effect of electron-phonon interaction on the optical conductivity of graphene plane is studied. It is found that the electron-phonon coupling increases the optical conductivity of graphene sheet in the low frequency region due to decreasing quasiparticle weight of electron excitation while the optical conductivity reduces in the high frequency region. The latter is due to role of electrical field's frequency.

  10. Waiting time distribution for electron transport in a molecular junction with electron-vibration interaction

    Science.gov (United States)

    Kosov, Daniel S.

    2017-02-01

    On the elementary level, electronic current consists of individual electron tunnelling events that are separated by random time intervals. The waiting time distribution is a probability to observe the electron transfer in the detector electrode at time t +τ given that an electron was detected in the same electrode at an earlier time t. We study waiting time distribution for quantum transport in a vibrating molecular junction. By treating the electron-vibration interaction exactly and molecule-electrode coupling perturbatively, we obtain the master equation and compute the distribution of waiting times for electron transport. The details of waiting time distributions are used to elucidate microscopic mechanism of electron transport and the role of electron-vibration interactions. We find that as nonequilibrium develops in the molecular junction, the skewness and dispersion of the waiting time distribution experience stepwise drops with the increase of the electric current. These steps are associated with the excitations of vibrational states by tunnelling electrons. In the strong electron-vibration coupling regime, the dispersion decrease dominates over all other changes in the waiting time distribution as the molecular junction departs far away from the equilibrium.

  11. Role of Interactions in Electronic Structure of a Two-Electron Quantum Dot Molecule

    Institute of Scientific and Technical Information of China (English)

    DONG Qing-Rui; XU Ying-Qiang; ZHANG Shi-Yong; NIU Zhi-Chuan

    2004-01-01

    @@ We have studied a two-electron quantum dot molecule in a magnetic field. The electron interaction is treated accurately by the direct diagonalization of the Hamiltonian matrix. We calculate two lowest energy levels of the two-electron quantum dot molecule in a magnetic field. Our results show that the electron interactions are significant, as they can change the total spin of the two-electron ground state of the system by adjusting the magnetic field between S = 0 and S = 1. The energy difference △E between the lowest S = 0 and S = 1 states is shown as a function of the axial magnetic field. We found that the energy difference between the lowest S = 0 and S = 1 states in the strong-B S = 0 state varies linearly. Our results provide a possible realization for a qubit to be fabricated by current growth techniques.

  12. Electron - whistler interaction at the Earth`s bow shock: 2. Electron pitch angle diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Veltri, P.; Zimbardo, G. [Universita della Calabria, Cosenza (Italy)

    1993-08-01

    In this paper the authors further examine the interactions of whistler waves with electrons in the bow shock, simulating a crossing made on Nov 7, 1977. The authors consider the effects of whistler waves and electrostatic noise on the electron distribution function, using a Monte Carlo technique. Their simulations are able to reproduce the moments of the distribution function, including spatial and velocity profiles. They conclude that the fields in the bow shock accelerate electrons, creating asymmetric distributions, which are filled in due to diffusion caused by the electrostatic noise, and which have the velocity distributions balanced due to pitch angle scattering of parallel electrons from whistler waves.

  13. Interaction of ultrarelativistic electron and proton bunches with dense plasmas

    CERN Document Server

    Rukhadze, A A

    2012-01-01

    Here we discuss the possibility of employment of ultrarelativistic electron and proton bunches for generation of high plasma wakefields in dense plasmas due to the Cherenkov resonance plasma-bunch interaction. We estimate the maximum amplitude of such a wake and minimum system length at which the maximum amplitude can be generated at the given bunch parameters.

  14. Interactivity Between Proteges and Scientists in an Electronic Mentoring Program

    Science.gov (United States)

    Bonnett, Cara; Wildemuth, Barbara M.; Sonnenwald, Diane H.

    2006-01-01

    Interactivity is defined by Henri (1992) as a three-step process involving communication of information, a response to this information, and a reply to that first response. It is a key dimension of computer-mediated communication, particularly in the one-on-one communication involved in an electronic mentoring program. This report analyzes the…

  15. ENERGETIC PHOTON AND ELECTRON INTERACTIONS WITH POSITIVE IONS

    Energy Technology Data Exchange (ETDEWEB)

    Phaneuf, Ronald A. [UNR

    2013-07-01

    The objective of this research is a deeper understanding of the complex multi-electron interactions that govern inelastic processes involving positive ions in plasma environments, such as those occurring in stellar cares and atmospheres, x-ray lasers, thermonuclear fusion reactors and materials-processing discharges. In addition to precision data on ionic structure and transition probabilities, high resolution quantitative measurements of ionization test the theoretical methods that provide critical input to computer codes used for plasma modeling and photon opacity calculations. Steadily increasing computational power and a corresponding emphasis on simulations gives heightened relevance to precise and accurate benchmark data. Photons provide a highly selective probe of the internal electronic structure of atomic and molecular systems, and a powerful means to better understand more complex electron-ion interactions.

  16. Electromagnetic Structure and Electron Acceleration in Shock–Shock Interaction

    Science.gov (United States)

    Nakanotani, Masaru; Matsukiyo, Shuichi; Hada, Tohru; Mazelle, Christian X.

    2017-09-01

    A shock–shock interaction is investigated by using a one-dimensional full particle-in-cell simulation. The simulation reproduces the collision of two symmetrical high Mach number quasi-perpendicular shocks. The basic structure of the shocks and ion dynamics is similar to that obtained by previous hybrid simulations. The new aspects obtained here are as follows. Electrons are already strongly accelerated before the two shocks collide through multiple reflection. The reflected electrons self-generate waves upstream between the two shocks before they collide. The waves far upstream are generated through the right-hand resonant instability with the anomalous Doppler effect. The waves generated near the shock are due to firehose instability and have much larger amplitudes than those due to the resonant instability. The high-energy electrons are efficiently scattered by the waves so that some of them gain large pitch angles. Those electrons can be easily reflected at the shock of the other side. The accelerated electrons form a power-law energy spectrum. Due to the accelerated electrons, the pressure of upstream electrons increases with time. This appears to cause the deceleration of the approaching shock speed. The accelerated electrons having sufficiently large Larmor radii are further accelerated through the similar mechanism working for ions when the two shocks are colliding.

  17. Generation of anomalously energetic suprathermal electrons by an electron beam interacting with a nonuniform plasma

    Science.gov (United States)

    Sydorenko, Dmytro; Kaganovich, Igor D.; Ventzek, Peter L. G.

    2016-10-01

    Electrons emitted from electrodes are accelerated by the sheath electric field and become the electron beams penetrating the plasma. The electron beam can interact with the plasma in collisionless manner via two-stream instability and produce suprathermal electrons. In order to understand the mechanism of suprathermal electrons acceleration, a beam-plasma system was simulated using a 1D3V particle-in-cell code EDIPIC. These simulation results show that the acceleration may be caused by the effects related to the plasma nonuniformity. The electron beam excites plasma waves whose wavelength and phase speed gradually decrease towards anode. The short waves near the anode accelerate plasma bulk electrons to suprathermal energies. Rich complexity of beam- plasma interaction phenomena was also observed: intermittency and multiple regimes of two-stream instability in a dc discharge, band structure of the growth rate of the two-stream instability of an electron beam propagating in a bounded plasma, multi-stage acceleration of electrons in a finite system.

  18. Tunable Electron-Electron Interactions in LaAlO_{3}/SrTiO_{3} Nanostructures

    Directory of Open Access Journals (Sweden)

    Guanglei Cheng

    2016-12-01

    Full Text Available The interface between the two complex oxides LaAlO_{3} and SrTiO_{3} has remarkable properties that can be locally reconfigured between conducting and insulating states using a conductive atomic force microscope. Prior investigations of “sketched” quantum dot devices revealed a phase in which electrons form pairs, implying a strongly attractive electron-electron interaction. Here, we show that these devices with strong electron-electron interactions can exhibit a gate-tunable transition from a pair-tunneling regime to a single-electron (Andreev bound state tunneling regime where the interactions become repulsive. The electron-electron interaction sign change is associated with a Lifshitz transition where the d_{xz} and d_{yz} bands start to become occupied. This electronically tunable electron-electron interaction, combined with the nanoscale reconfigurability of this system, provides an interesting starting point towards solid-state quantum simulation.

  19. Tunable Electron-Electron Interactions in LaAlO3/SrTiO3 Nanostructures

    Science.gov (United States)

    Cheng, Guanglei; Tomczyk, Michelle; Tacla, Alexandre B.; Lee, Hyungwoo; Lu, Shicheng; Veazey, Josh P.; Huang, Mengchen; Irvin, Patrick; Ryu, Sangwoo; Eom, Chang-Beom; Daley, Andrew; Pekker, David; Levy, Jeremy

    2016-10-01

    The interface between the two complex oxides LaAlO3 and SrTiO3 has remarkable properties that can be locally reconfigured between conducting and insulating states using a conductive atomic force microscope. Prior investigations of "sketched" quantum dot devices revealed a phase in which electrons form pairs, implying a strongly attractive electron-electron interaction. Here, we show that these devices with strong electron-electron interactions can exhibit a gate-tunable transition from a pair-tunneling regime to a single-electron (Andreev bound state) tunneling regime where the interactions become repulsive. The electron-electron interaction sign change is associated with a Lifshitz transition where the dx z and dy z bands start to become occupied. This electronically tunable electron-electron interaction, combined with the nanoscale reconfigurability of this system, provides an interesting starting point towards solid-state quantum simulation.

  20. Electron interactions in graphene through an effective Coulomb potential

    Science.gov (United States)

    Rodrigues, Joao N. B.; Adam, Shaffique

    A recent numerical work [H.-K. Tang et al, PRL 115, 186602 (2015)] considering graphene's π-electrons interacting through an effective Coulomb potential that is finite at short-distances, stressed the importance of the sp2 -electrons in determining the semimetal to Mott insulator phase transition in graphene. Some years ago, I. F. Herbut [PRL 97, 146401 (2006)] studied such a transition by mapping graphene's π-electrons into a Gross-Neveu model. From a different perspective, D. T. Son [PRB 75, 235423 (2007)] put the emphasis on the long-range interactions by modelling graphene as Dirac fermions interacting through a bare Coulomb potential. Here we build on these works and explore the phase diagram of Dirac fermions interacting through an effective Coulomb-like potential screened at short-distances. The interaction potential used allows for analytic results that controllably switch between the two perspectives above. This work was supported by the Singapore National Research Foundation (NRF-NRFF2012-01 and CA2DM medium-sized centre program) and by the Singapore Ministry of Education and Yale-NUS College (R-607-265-01312).

  1. Automated Placement of Multiple Stereo Cameras

    OpenAIRE

    Malik, Rahul; Bajcsy, Peter

    2008-01-01

    International audience; This paper presents a simulation framework for multiple stereo camera placement. Multiple stereo camera systems are becoming increasingly popular these days. Applications of multiple stereo camera systems such as tele-immersive systems enable cloning of dynamic scenes in real-time and delivering 3D information from multiple geographic locations to everyone for viewing it in virtual (immersive) 3D spaces. In order to make such multi stereo camera systems ubiquitous, sol...

  2. Two-photon absorption measurements in graphene fragments: Role of electron-electron interactions

    Science.gov (United States)

    Sandhu, A.; Roberts, A.; Aryanpour, K.; Shukla, A.; Mazumdar, S.

    2012-02-01

    Many-body interactions in graphene are an active field of research. There is a clear evidence of strong electron correlation effects in other carbon based materials which have the same sp^2 hybridization as graphene. For example, in linear-polyenes, the electron-electron interactions are considered responsible for the occurrence of lowest two-photon state below the optical one-photon state. The electronic correlation in these linear systems is a strong function of the chain length. Thus, it is pertinent to question if the two-dimensional graphene fragments also exhibit strong correlation effects and how these effects scale with fragment size. Using a white light super-continuum source, we perform z-scan measurements to extract frequency-dependent two-photon absorption coefficients in symmetric molecular fragments of graphene, e.g. coronene and hexabenzocoronene. A comparison of one-photon and two-photon absorption coefficients is then used to uncover the extent of correlation effects. In the smallest fragment, coronene, our results indicate a strong signature of the Coulomb interactions. We will discuss how the importance of electron-electron interaction varies with system size and its implication for the correlation effects in graphene.

  3. Controlling electron quantum dot qubits by spin-orbit interactions

    Energy Technology Data Exchange (ETDEWEB)

    Stano, P.

    2007-01-15

    Single electron confined in a quantum dot is studied. A special emphasis is laid on the spin properties and the influence of spin-orbit interactions on the system. The study is motivated by a perspective exploitation of the spin of the confined electron as a qubit, a basic building block of in a foreseen quantum computer. The electron is described using the single band effective mass approximation, with parameters typical for a lateral electrostatically defined quantum dot in a GaAs/AlGaAs heterostructure. The stemming data for the analysis are obtained by numerical methods of exact diagonalization, however, all important conclusions are explained analytically. The work focuses on three main areas -- electron spectrum, phonon induced relaxation and electrically and magnetically induced Rabi oscillations. It is shown, how spin-orbit interactions influence the energy spectrum, cause finite spin relaxation and allow for all-electrical manipulation of the spin qubit. Among the main results is the discovery of easy passages, where the spin relaxation is unusually slow and the qubit is protected against parasitic electrical fields connected with manipulation by resonant electromagnetic fields. The results provide direct guide for manufacturing quantum dots with much improved properties, suitable for realizing single electron spin qubits. (orig.)

  4. Hearing damage by personal stereo

    DEFF Research Database (Denmark)

    Hammershøi, Dorte; Ordoñez, Rodrigo Pizarro; Reuter, Karen

    2006-01-01

    The technological development within personal stereo systems, such as MP3 players, iPods etc., has changed music listening habits from home entertainment to everyday and everywhere use. The technology has developed considerably, since the introduction of CD walkmen, and high-level low...... of the measurement methods for noise exposure used, and technical issues that may explain the high exposure levels....

  5. Electron-phonon interaction in high temperature superconductors

    Directory of Open Access Journals (Sweden)

    H. Khosroabadi

    2006-09-01

    Full Text Available   We explore the important role of the strong electron-phonon interaction in high temperature superconductivity through the study of the results of some important experiments, such as inelastic neutron and X-ray scattering, angle resolved photoemission spectroscopy, and isotope effects. We also present our computational results of the eigenvalues and eigenvectors of the Ag Raman modes, and the ionic displacement dependence of the electronic band structure by density functional theory. It is clearly evident that the role of phonons in the mechanism behind the high-temperature superconducting state should be seriously considered.

  6. Interaction of ion-acoustic solitons with electron beam in warm plasmas with superthermal electrons

    CERN Document Server

    Esfandyari-Kalejahi, A R

    2012-01-01

    Propagation of ion-acoustic solitary waves (IASWs) is studied using the hydrodynamic equations coupled with the Poisson equation in a warm plasma consisting of adiabatic ions and superthermal (Kappa distributed) electrons in presence of an electron-beam component. In the linear limit, the dispersion relation for ion-acoustic (IA) waves is obtained by linearizing of basic equations. On the other hand, in the nonlinear analysis, an energy-balance like equation involving Sagdeev's pseudo-potential is derived in order to investigate arbitrary amplitude IA solitons. The Mach number range is determined in which, propagation and characteristics of IA solitons are analyzed both parametrically and numerically. The variation of amplitude and width of electrostatic (ES) excitations as a result of superthermality (via) and also the physical parameters (ion temperature, soliton speed, electron-beam density and electron-beam velocity) are examined. A typical interaction between IASWs and the electron-beam in plasma is conf...

  7. Jensen-Feynman approach to the statistics of interacting electrons.

    Science.gov (United States)

    Pain, Jean-Christophe; Gilleron, Franck; Faussurier, Gérald

    2009-08-01

    Faussurier [Phys. Rev. E 65, 016403 (2001)] proposed to use a variational principle relying on Jensen-Feynman (or Gibbs-Bogoliubov) inequality in order to optimize the accounting for two-particle interactions in the calculation of canonical partition functions. It consists of a decomposition into a reference electron system and a first-order correction. The procedure appears to be very efficient in order to evaluate the free energy and the orbital populations. In this work, we present numerical applications of the method and propose to extend it using a reference energy which includes the interaction between two electrons inside a given orbital. This is possible, thanks to our efficient recursion relation for the calculation of partition functions. We also show that a linear reference energy, however, is usually sufficient to achieve a good precision and that the most promising way to improve the approach of Faussurier is to apply Jensen's inequality to a more convenient convex function.

  8. Gyroresonant interaction of energetic trapped electrons and protons

    Science.gov (United States)

    Villalon, Elena; Silevitch, Michael B.; Burke, William J.; Rothwell, Paul L.

    The present consideration of the theory of gyroresonant interactions of energetic trapped electrons and protons with ducted EM cyclotron waves in the earth's radiation zones derives a set of equations, based on the Fokker-Planck theory of pitch-angle diffusion, which describe the temporal evolution of the number of particles in the flux tube, and the energy density of waves, for (1) the interaction of Alfven waves with protons and (2) that of whistler waves with electrons. Attention is given to the reflection of the waves in the ionosphere. To dump the energetic particles from the radiation belts efficiently, the reflection coefficient must be close to unity to facilitate the growth of wave amplitudes; precipitating particle fluxes may then act as a positive feedback to raise the height-integrated conductivity of the ionosphere. This conductivity in turn enhances wave reflection.

  9. The electron-atom interaction in partially ionized dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Omarbakiyeva, Yu A; Ramazanov, T S; Roepke, G [IETP, Al Farabi Kazakh National University, Tole Bi 96a, Almaty 050012 (Kazakhstan)], E-mail: yultuz@physics.kz

    2009-05-29

    The electron-atom interaction is considered in dense partially ionized plasmas. The separable potential is constructed from scattering data using effective radius theory. Parameters of the interaction potential were obtained from phase shifts, scattering length and effective radius. The binding energy of the electron in the H{sup -} ion is determined for the singlet channel on the basis of the reconstructed separable potential. In dense plasmas, the influence of the Pauli exclusion principle on the phase shifts and the binding energy is considered. Due to the Pauli blocking, the binding energy vanishes at the Mott density. At that density the behavior of the phase shifts is drastically changed. This leads to modifications of macroscopic properties such as composition and transport coefficients.

  10. Interacting Electrons in Graphene: Fermi Velocity Renormalization and Optical Response.

    Science.gov (United States)

    Stauber, T; Parida, P; Trushin, M; Ulybyshev, M V; Boyda, D L; Schliemann, J

    2017-06-30

    We have developed a Hartree-Fock theory for electrons on a honeycomb lattice aiming to solve a long-standing problem of the Fermi velocity renormalization in graphene. Our model employs no fitting parameters (like an unknown band cutoff) but relies on a topological invariant (crystal structure function) that makes the Hartree-Fock sublattice spinor independent of the electron-electron interaction. Agreement with the experimental data is obtained assuming static self-screening including local field effects. As an application of the model, we derive an explicit expression for the optical conductivity and discuss the renormalization of the Drude weight. The optical conductivity is also obtained via precise quantum Monte Carlo calculations which compares well to our mean-field approach.

  11. Relativistic electron mirrors from high intensity laser nanofoil interactions

    Energy Technology Data Exchange (ETDEWEB)

    Kiefer, Daniel

    2012-12-21

    The reflection of a laser pulse from a mirror moving close to the speed of light could in principle create an X-ray pulse with unprecedented high brightness owing to the increase in photon energy and accompanying temporal compression by a factor of 4γ{sup 2}, where γ is the Lorentz factor of the mirror. While this scheme is theoretically intriguingly simple and was first discussed by A. Einstein more than a century ago, the generation of a relativistic structure which acts as a mirror is demanding in many different aspects. Recently, the interaction of a high intensity laser pulse with a nanometer thin foil has raised great interest as it promises the creation of a dense, attosecond short, relativistic electron bunch capable of forming a mirror structure that scatters counter-propagating light coherently and shifts its frequency to higher photon energies. However, so far, this novel concept has been discussed only in theoretical studies using highly idealized interaction parameters. This thesis investigates the generation of a relativistic electron mirror from a nanometer foil with current state-of-the-art high intensity laser pulses and demonstrates for the first time the reflection from those structures in an experiment. To achieve this result, the electron acceleration from high intensity laser nanometer foil interactions was studied in a series of experiments using three inherently different high power laser systems and free-standing foils as thin as 3nm. A drastic increase in the electron energies was observed when reducing the target thickness from the micrometer to the nanometer scale. Quasi-monoenergetic electron beams were measured for the first time from ultrathin (≤5nm) foils, reaching energies up to ∝35MeV. The acceleration process was studied in simulations well-adapted to the experiments, indicating the transition from plasma to free electron dynamics as the target thickness is reduced to the few nanometer range. The experience gained from those

  12. High Efficiency Electron-Laser Interactions in Tapered Helical Undulators

    Science.gov (United States)

    Duris, Joseph Patrick

    Efficient coupling of relativistic electron beams with high power radiation lies at the heart of advanced accelerator and light source research and development. The inverse free electron laser is a stable accelerator capable of harnessing very high intensity laser electric fields to efficiently transfer large powers from lasers to electron beams. In this dissertation, we first present the theoretical framework to describe the interaction, and then apply our improved understanding of the IFEL to the design and numerical study of meter-long, GeV IFELs for compact light sources. The central experimental work of the dissertation is the UCLA BNL helical inverse free electron laser experiment at the Accelerator Test Facility in Brookhaven National Laboratory which used a strongly tapered 54cm long, helical, permanent magnet undulator and a several hundred GW CO2 laser to accelerate electrons from 52 to 106MeV, setting new records for inverse free electron laser energy gain (54MeV) and average accelerating gradient (100MeV/m). The undulator design and fabrication as well as experimental diagnostics are presented. In order to improve the stability and quality of the accelerated electron beam, we redesigned the undulator for a slightly reduced output energy by modifying the magnet gap throughout the undulator, and we used this modified undulator to demonstrated capture of >25% of the injected beam without prebunching. In the study of heavily loaded GeV inverse free electron lasers, we show that a majority of the power may be transferred from a laser to the accelerated electron beam. Reversing the process to decelerate high power electron beams, a mechanism we refer to as tapering enhanced stimulated superradiant amplification, offers a clear path to high power light sources. We present studies of radiation production for a wide range of wavelengths (10mum, 13nm, and 0.3nm) using this method and discuss the design for a deceleration experiment using the same undulator used

  13. MUSIC - Multifunctional stereo imaging camera system for wide angle and high resolution stereo and color observations on the Mars-94 mission

    Science.gov (United States)

    Oertel, D.; Jahn, H.; Sandau, R.; Walter, I.; Driescher, H.

    1990-10-01

    Objectives of the multifunctional stereo imaging camera (MUSIC) system to be deployed on the Soviet Mars-94 mission are outlined. A high-resolution stereo camera (HRSC) and wide-angle opto-electronic stereo scanner (WAOSS) are combined in terms of hardware, software, technology aspects, and solutions. Both HRSC and WAOSS are push-button instruments containing a single optical system and focal plates with several parallel CCD line sensors. Emphasis is placed on the MUSIC system's stereo capability, its design, mass memory, and data compression. A 1-Gbit memory is divided into two parts: 80 percent for HRSC and 20 percent for WAOSS, while the selected on-line compression strategy is based on macropixel coding and real-time transform coding.

  14. D-state Rydberg electrons interacting with ultracold atoms

    Energy Technology Data Exchange (ETDEWEB)

    Krupp, Alexander Thorsten

    2014-10-02

    This thesis was established in the field of ultracold atoms where the interaction of highly excited D-state electrons with rubidium atoms was examined. This work is divided into two main parts: In the first part we study D-state Rydberg molecules resulting from the binding of a D-state Rydberg electron to a ground state rubidium atom. We show that we can address specific rovibrational molecular states by changing our laser detuning and thus create perfectly aligned axial or antialigned toroidal molecules, in good agreement with our theoretical calculations. Furthermore the influence of the electric field on the Rydberg molecules was investigated, creating novel states which show a different angular dependence and alignment. In the second part of this thesis we excite single D-state Rydberg electrons in a Bose-Einstein condensate. We study the lifetime of these Rydberg electrons, the change of the shape of our condensate and the atom losses in the condensate due to this process. Moreover, we observe quadrupolar shape oscillations of the whole condensate created by the consecutive excitation of Rydberg atoms and compare all results to previous S-state measurements. In the outlook we propose a wide range of further experiments including the proposal of imaging a single electron wavefunction by the imprint of its orbit into the Bose-Einstein condensate.

  15. Van der Waals forces and electron-electron interactions in two strained graphene layers

    Science.gov (United States)

    Sharma, Anand; Harnish, Peter; Sylvester, Alexander; Kotov, Valeri N.

    2014-03-01

    We evaluate the van der Waals (vdW) interaction energy at T=0 between two undoped graphene layers which are separated by a finite distance. Our study is carried out within the Random Phase Approximation and the interaction energy is obtained for variation in the strength of effective Coulomb interaction and anisotropy due to applied uniaxial strain. We consider the following three models for the anisotropic case: a) where one of the two layers is uniaxially strained, b) the two layers are strained in the same direction, and c) one of the layers is strained in the perpendicular direction. We find that for all the three models and any given value of the coupling, the vdW interaction energy increases with increasing anisotropy. The effect is most striking for the case when both the layers are strained in the parallel direction where we observe up to an order of magnitude increase in the strained graphene relative to the unstrained case. We also investigate the effect of intra-layer electron-electron interactions in the region of large separation between the strained graphene layers. We conclude that the many-body contributions to the correlation energy are non-negligible and the vdW interaction energy decreases as a function of increasing distance between the layers. Alexander Sylvester acknowledges financial assistance from the Research Experiences for Undergraduates (REU) Program of the National Science Foundation (NSF) focussing on complex materials.

  16. User-interactive electronic skin for instantaneous pressure visualization

    Science.gov (United States)

    Wang, Chuan; Hwang, David; Yu, Zhibin; Takei, Kuniharu; Park, Junwoo; Chen, Teresa; Ma, Biwu; Javey, Ali

    2013-10-01

    Electronic skin (e-skin) presents a network of mechanically flexible sensors that can conformally wrap irregular surfaces and spatially map and quantify various stimuli. Previous works on e-skin have focused on the optimization of pressure sensors interfaced with an electronic readout, whereas user interfaces based on a human-readable output were not explored. Here, we report the first user-interactive e-skin that not only spatially maps the applied pressure but also provides an instantaneous visual response through a built-in active-matrix organic light-emitting diode display with red, green and blue pixels. In this system, organic light-emitting diodes (OLEDs) are turned on locally where the surface is touched, and the intensity of the emitted light quantifies the magnitude of the applied pressure. This work represents a system-on-plastic demonstration where three distinct electronic components—thin-film transistor, pressure sensor and OLED arrays—are monolithically integrated over large areas on a single plastic substrate. The reported e-skin may find a wide range of applications in interactive input/control devices, smart wallpapers, robotics and medical/health monitoring devices.

  17. Experimental investigation of electron beam wave interactions utilising short pulses

    CERN Document Server

    Wiggins, S M

    2000-01-01

    Experiments have investigated the production of ultra-short electromagnetic pulses and their interaction with electrons in various resonant structures. Diagnostic systems used in the measurements included large bandwidth detection systems for capturing the short pulses. Deconvolution techniques have been applied to account for bandwidth limitation of the detection systems and to extract the actual pulse amplitudes and durations from the data. A Martin-Puplett interferometer has been constructed for use as a Fourier transform spectrometer. The growth of superradiant electromagnetic spikes from short duration (0.5-1.0 ns), high current (0.6-2.0 kA) electron pulses has been investigated in a Ka-band Cherenkov maser and Ka- and W-band backward wave oscillators (BWO). In the Cherenkov maser, radiation spikes were produced with a peak power = 70 ps and a bandwidth <= 19 %. It is shown that coherent spontaneous emission from the leading edge of the electron pulse drives these interactions, giving rise to self-amp...

  18. [Electronic learning: interactive learning in medicine or Socrates in electronic guise].

    Science.gov (United States)

    Wautier, J-L; Vileyn, F; Lefrère, J-J

    2005-06-01

    E-learning has been widely used for training in different fields. More recently, it was introduced during medical studies or for continuous medical education. The Canadian Universities are pioneers in e-learning creating special departments dedicated to pedagogy. Developing countries like Brazil or Central Europe have made some pilot experiments, which were successful. Several electronic companies have given a free access to the programmes and sites. The use of electronic media leads to an adaptation of teaching methods making them more interactive.

  19. Relativistic collision rate calculations for electron-air interactions

    Energy Technology Data Exchange (ETDEWEB)

    Graham, G. [EG and G Energy Measurements, Inc., Los Alamos, NM (United States); Roussel-Dupre, R. [Los Alamos National Lab., NM (United States). Space Science and Technologies

    1992-12-16

    The most recent data available on differential cross sections for electron-air interactions are used to calculate the avalanche, momentum transfer, and energy loss rates that enter into the fluid equations. Data for the important elastic, inelastic, and ionizing processes are generally available out to electron energies of 1--10 kev. Prescriptions for extending these cross sections to the relativistic regime are presented. The angular dependence of the cross sections is included where data is available as is the doubly differential cross section for ionizing collisions. The collision rates are computed by taking moments of the Boltzmann collision integrals with the assumption that the electron momentum distribution function is given by the Juettner distribution function which satisfies the relativistic H- theorem and which reduces to the familiar Maxwellian velocity distribution in the nonrelativistic regime. The distribution function is parameterized in terms of the electron density, mean momentum, and thermal energy and the rates are therefore computed on a two-dimensional grid as a function of mean kinetic energy and thermal energy.

  20. Signature of electron-phonon interaction in high temperature superconductors

    Directory of Open Access Journals (Sweden)

    Vinod Ashokan

    2011-09-01

    Full Text Available The theory of thermal conductivity of high temperature superconductors (HTS based on electron and phonon line width (life times formulation is developed with Quantum dynamical approach of Green's function. The frequency line width is observed as an extremely sensitive quantity in the transport phenomena of HTS as a collection of large number of scattering processes. The role of resonance scattering and electron-phonon interaction processes is found to be most prominent near critical temperature. The theory successfully explains the spectacular behaviour of high Tc superconductors in the vicinity of transition temperature. A successful agreement between theory and experiment has been obtained by analyzing the thermal conductivity data for the sample La1.8Sr0.2CuO4 in the temperature range 0 − 200K. The theory is equally and successfully applicable to all other high Tc superconductors.

  1. An Interactive Network Laboratory for Electronic Engineering Education

    Institute of Scientific and Technical Information of China (English)

    Shao-Chun Fan; Jian-Jun Jiang; Wen-Qing Liu

    2007-01-01

    The advantage of the network laboratory is the better flexibility of lab experiments by allowing remote control from different locations at a freely chosen time. In engineering education, the work should not only be focused on the technical realization of virtual or remote access experiments, but also on the achievement of its pedagogical goals. In this paper, an interactive laboratory is introduced which is based on the online tutoring system, virtual and remote access experiments. It has been piloted in the Department of Electronic Science and Technology, HUST. Some pedagogical issues for electronic engineering laboratory design, the development of a multi-server-based distributed architecture for the reduction of network latency and implementations of the function module are presented. Finally, the system is proved valid by an experiment.

  2. Compact stereo endoscopic camera using microprism arrays.

    Science.gov (United States)

    Yang, Sung-Pyo; Kim, Jae-Jun; Jang, Kyung-Won; Song, Weon-Kook; Jeong, Ki-Hun

    2016-03-15

    This work reports a microprism array (MPA) based compact stereo endoscopic camera with a single image sensor. The MPAs were monolithically fabricated by using two-step photolithography and geometry-guided resist reflow to form an appropriate prism angle for stereo image pair formation. The fabricated MPAs were transferred onto a glass substrate with a UV curable resin replica by using polydimethylsiloxane (PDMS) replica molding and then successfully integrated in front of a single camera module. The stereo endoscopic camera with MPA splits an image into two stereo images and successfully demonstrates the binocular disparities between the stereo image pairs for objects with different distances. This stereo endoscopic camera can serve as a compact and 3D imaging platform for medical, industrial, or military uses.

  3. Effects of intermolecular interaction on inelastic electron tunneling spectra

    Science.gov (United States)

    Kula, Mathias; Luo, Yi

    2008-02-01

    We have examined the effects of intermolecular interactions on the inelastic electron tunneling spectroscopy (IETS) of model systems: a pair of benzenethiol or a pair of benzenedithiol sandwiched between gold electrodes. The dependence of the IETS on the mutual position of and distance between the paired molecules has been predicted and discussed in detailed. It is shown that, although in most cases, there are clear spectral fingerprints present which allow identification of the actual structures of the molecules inside the junction. Caution must be exercised since some characteristic lines can disappear at certain symmetries. The importance of theoretical simulation is emphasized.

  4. Interacting electrons in ballistic conformal billiard quantum dots

    Science.gov (United States)

    Murthy, Ganpathy; Mathur, Harsh; Shankar, Ramamurti

    2004-03-01

    Interacting electrons in a ballistic quantum dot present a novel regime of disorder + interactions. An instability of the ground state towards a spontaneous deformation of the Fermi surface (the Pomeranchuk transition) has been found by the present authors[1], by assuming that Random Matrix Theory describes the states in the Thouless shell near the Fermi energy. However, the question of whether the mesoscopic transition occurs before the bulk transition remains open[2]. Here we describe calculations on the conformal billiard[3] and attempt to see how well RMT assumptions hold, and to what extent the physics of the transition is described by our previous work. 1. G. Murthy, R. Shankar, D. Herman, and H. Mathur, cond-mat/0306529. 2. S. Adam, P. W. Brouwer, and P. Sharma, cond-mat/0309074. 3. M. V. Berry and M. Robnik, J. Phys. A19, 669 (1986).

  5. Efficient view synthesis from uncalibrated stereo

    Science.gov (United States)

    Braspenning, Ralph; Op de Beeck, Marc

    2006-02-01

    For multiview auto-stereoscopic 3D displays, available stereo content needs to be converted to multiview content. In this paper we present a method to efficiently synthesize new views based on the two existing views from the stereo input. This method can be implemented in real-time and is also capable of handling uncalibrated stereo input. Good performance is shown compared to state-of-the-art disparity estimation algorithms and view rendering methods.

  6. Electron-electron interactions and lattice distortions in the perovskite titanates

    Science.gov (United States)

    Bjaalie, Lars

    A two-dimensional electron gas (2DEG) with the unprecedented high density of 3x1014 (corresponding to 1/2 electron per interface unit cell area) can be formed at the interface between SrTiO3 and a rare-earth titanate (RTiO3). The 2DEG resides in the SrTiO3, and arises from a polar discontinuity at the interface. The formation of this 2DEG has led us to study these perovskite titanates in detail. Some of these compounds are Mott insulators, where a Mott-Hubbard gap opens up between partially filled Ti 3 d bands. This talk focuses on the importance of the interplay between electron-electron interactions and lattice distortions in these complex oxides, which we study with density functional theory using a hybrid functional, capable of correctly describing electron localization and Mott-insulating behavior. These effects are crucial to understanding the metal-to-insulator transition as a function of electron density. Indeed, very thin SrTiO3 layers inserted in GdTiO3 show insulating behavior, in contrast to the metallic character of thicker layers in which the electrons form a 2DEG. The same physics is observed in bulk SrTiO3 when doped with 1/2 electron per Ti atom. Charge localization and lattice distortions also govern the formation of small hole polarons in the rare-earth titanates. We demonstrate that these polarons impact the optical absorption measurements commonly used to determine the value of the Mott-Hubbard gap. Work performed in collaboration with Anderson Janotti, Burak Himmetoglu, and Chris G. Van de Walle, and supported by NSF and ARO.

  7. Modified Monte Carlo method for study of electron transport in degenerate electron gas in the presence of electron-electron interactions, application to graphene

    Science.gov (United States)

    Borowik, Piotr; Thobel, Jean-Luc; Adamowicz, Leszek

    2017-07-01

    Standard computational methods used to take account of the Pauli Exclusion Principle into Monte Carlo (MC) simulations of electron transport in semiconductors may give unphysical results in low field regime, where obtained electron distribution function takes values exceeding unity. Modified algorithms were already proposed and allow to correctly account for electron scattering on phonons or impurities. Present paper extends this approach and proposes improved simulation scheme allowing including Pauli exclusion principle for electron-electron (e-e) scattering into MC simulations. Simulations with significantly reduced computational cost recreate correct values of the electron distribution function. Proposed algorithm is applied to study transport properties of degenerate electrons in graphene with e-e interactions. This required adapting the treatment of e-e scattering in the case of linear band dispersion relation. Hence, this part of the simulation algorithm is described in details.

  8. 2012 Gordon Research Conference, Electron donor-acceptor interactions, August 5-10 2012

    Energy Technology Data Exchange (ETDEWEB)

    McCusker, James [Michigan State Univ., East Lansing, MI (United States)

    2012-08-10

    The upcoming incarnation of the Gordon Research Conference on Electron Donor Acceptor Interactions will feature sessions on classic topics including proton-coupled electron transfer, dye-sensitized solar cells, and biological electron transfer, as well as emerging areas such as quantum coherence effects in donor-acceptor interactions, spintronics, and the application of donor-acceptor interactions in chemical synthesis.

  9. Experimental studies of electron-phonon interactions in gallium nitride

    CERN Document Server

    Stanton, N M

    2001-01-01

    This thesis presents an experimental investigation of the electron-phonon interaction in GaN. Bulk epilayers, grown by MBE, and AIGaN/GaN heterostructure grown by MOCVD, have been studied. The energy relaxation rate for hot electrons has been measured over a wide range of temperatures, allowing both acoustic and optic phonon emission to be studied in GaN epilayers. Direct phonon measurements, both studying the emission and absorption processes, have been performed. Detection of phonons emitted when hot electrons relax their excess energy complements the measurements of relaxation rates. Absorption of acoustic phonons by the epilayers, using both fixed and extended metal film phonon sources, allowed investigation into the effectiveness of the 2k sub F cutoff in the low mobility layers. The experimental findings are compared with the predictions of theory. AIGaN/GaN heterostructures were characterised and measurements of the energy relaxation rate in the temperature range 4K-40K obtained. Excellent agreement wi...

  10. Accelerated electron populations formed by Langmuir wave-caviton interactions

    CERN Document Server

    Sircombe, N J; Dendy, R O

    2004-01-01

    Direct numerical simulations of electron dynamics in externally driven electrostatic waves have been carried out using a relativistic two-fluid one-dimensional Vlasov-Poisson code. When the driver wave has sufficiently large amplitude, ion density holes (cavitons) form. The interaction between these cavitons and other incoming Langmuir waves gives rise to substantial local acceleration of groups of electrons, and fine jet-like structures arise in electron phase space. We show that these jets are caused by wave-breaking when finite amplitude Langmuir waves experience the ion density gradient at the leading edge of the holes, and are not caused by caviton burn-out. An analytical two-fluid model gives the critical density gradient and caviton depth for which this process can occur. In particular, the density gradient critically affects the rate at which a Langmuir wave, moving into the caviton, undergoes Landau damping. This treatment also enables us to derive analytical estimates for the maximum energy of accel...

  11. Spin g -factor due to electronic interactions in graphene

    Science.gov (United States)

    Menezes, Natália; Alves, Van Sérgio; Marino, E. C.; Nascimento, Leonardo; Nascimento, Leandro O.; Morais Smith, C.

    2017-06-01

    The gyromagnetic factor is an important physical quantity relating the magnetic-dipole moment of a particle to its spin. The electron spin g -factor in vacuo is one of the best model-based theoretical predictions ever made, showing agreement with the measured value up to ten parts per trillion [J. Schwinger, Phys. Rev. 73, 416 (1948), 10.1103/PhysRev.73.416; R. S. Van Dyck, Jr. et al., Phys. Rev. Lett. 59, 26 (1987), 10.1103/PhysRevLett.59.26; D. Hanneke et al., Phys. Rev. Lett. 100, 120801 (2008), 10.1103/PhysRevLett.100.120801; T. Aoyama et al., Phys. Rev. Lett. 109, 111807 (2012), 10.1103/PhysRevLett.109.111807]. However, for electrons in a material the g -factor is modified with respect to its value in vacuo because of environment interactions. Here, we show how interaction effects lead to the spin g -factor correction in graphene by considering the full electromagnetic interaction in the framework of pseudo-QED [A. Kovner et al., Phys. Rev. B 42, 4748 (1990), 10.1103/PhysRevB.42.4748; N. Dorey et al., Nucl. Phys. B 386, 614 (1992), 10.1016/0550-3213(92)90632-L; S. Teber, Phys. Rev. D 86, 025005 (2012), 10.1103/PhysRevD.86.025005; S. Teber, Phys. Rev. D 89, 067702 (2014), 10.1103/PhysRevD.89.067702; E. C. Marino, Nucl. Phys. B 408, 551 (1993), 10.1016/0550-3213(93)90379-4]. We compare our theoretical prediction with experiments performed on graphene deposited on SiO2 and SiC, and we find a very good agreement between them.

  12. 3D Medical Electronic Endoscope System Based on Binocular Stereo Vision%基于双目立体视觉的医用三维电子内窥镜系统

    Institute of Scientific and Technical Information of China (English)

    冯大伟; 姜会林; 张光伟

    2012-01-01

    为了施行较为复杂的微创外科手术,设计了医用三维电子内窥镜系统,对系统的工作原理、显示方式等进行了分析.该系统基于双目立体视觉原理,采用双CCD摄像机模拟人眼实现了机器立体视觉;利用Zemax软件辅助设计了双光路内窥镜光学系统;通过比较几种立体显示方式的优缺点,选择了无源偏振眼镜立体显示方法,该方法采用基于FPGA的时分制立体显示技术,左右图像以100Hz帧频交替显示,并与液晶调制屏同步,观察者佩戴偏振眼镜即可观察到清晰无闪烁立体图像.经临床试验表明:简化了的光学系统的电子内窥镜图像质量得到显著提高;图像帧频达到100Hz,无闪烁感,且无停顿、拖尾、扭曲和停滞等现象.该系统可广泛应用于微创外科手术中,并可作为腹腔手术机器人的显示系统使用.%In order to perform more complex minimally invasive surgery, we designed 3D medical electronic endoscope system, and analyzed the system principle and display mode. The system based on the principle of binocular stereo vision achieves 3D machine vision, adopting the dual CCD cameras to simulate the human eye. A dual-optical endoscope system is designed by "Zemax" software. We choose the passive polarized glasses stereoscopic display through comparing the advantages and disadvantages of several 3D display ways, and this way adopts the time-division 3D display technology based on FPGA, the left and right images alternately display with 100Hz frame rate, and synchronize with the modulated LCD screen. When the viewers wear polarized glasses, they can observe the clear stereoscopic images without flicker. The clinical tests indicate that the images quality of electronic endoscope significantly improved by simplified optical system, the image frame rate reaches to 100Hz and is not flickering. The images have not stop, tailing, twist, and stagnation. The system can be widely used in minimally

  13. Low Cost Interactive Electronic Whiteboard Using Nintendo Wii Remote

    Directory of Open Access Journals (Sweden)

    Dalbir Singh

    2010-01-01

    Full Text Available Problem statement: The application of interactive whiteboard offers extensive benefits in the learning and teaching process for classroom environment. The high cost associated with commercial interactive whiteboard may hinder its application in primary or secondary school, especially in developing countries. Thus, this study describes the methods used to create a low cost interactive and viable electronic whiteboard by using the capabilities of the Nintendo Wiimotes. It also looks at the possibility of whether this much cheaper technology can be fully utilized to create better tools for in-class learning. Approach: Several technical aspects of the Wii Remote are examined, how this technology can be used on a low cost interactive whiteboard and how the system can be connected to your computer and LCD projector/screen. Result: This system has a stand-alone architecture, consists of a PC. The input client was responsible for getting the input data and connecting the Wii Remotes using a Bluetooth connection. The PC handles the software engine and display module. The user sends the IR source light to Wiimote by pressing the IR Pens switch button and then the Wiimote sends data to the PC via a Bluetooth connection. Conclusion/Recommendations: The genre of the system makes it more suitable in learning environments such as schools or universities. The main target groups of the system are lecturers, teachers or students (during presentation or in class exercise. Therefore, it was necessary to simplify the software design and control mechanism in order to support these main target groups.

  14. An assembly system based on industrial robot with binocular stereo vision

    Science.gov (United States)

    Tang, Hong; Xiao, Nanfeng

    2017-01-01

    This paper proposes an electronic part and component assembly system based on an industrial robot with binocular stereo vision. Firstly, binocular stereo vision with a visual attention mechanism model is used to get quickly the image regions which contain the electronic parts and components. Secondly, a deep neural network is adopted to recognize the features of the electronic parts and components. Thirdly, in order to control the end-effector of the industrial robot to grasp the electronic parts and components, a genetic algorithm (GA) is proposed to compute the transition matrix and the inverse kinematics of the industrial robot (end-effector), which plays a key role in bridging the binocular stereo vision and the industrial robot. Finally, the proposed assembly system is tested in LED component assembly experiments, and the results denote that it has high efficiency and good applicability.

  15. Electron-electron interactions, topological phase, and optical properties of a charged artificial benzene ring

    Science.gov (United States)

    Ozfidan, Isil; Vladisavljevic, Milos; Korkusinski, Marek; Hawrylak, Pawel

    2015-12-01

    We present a theory of the electronic and optical properties of a charged artificial benzene ring (ABR). The ABR is described by the extended Hubbard model solved using exact diagonalization methods in both real and Fourier space as a function of the tunneling matrix element t , Hubbard on-site repulsion U , and interdot interaction V . In the strongly interacting case, we discuss exact analytical results for the spectrum of the hole in a half-filled ABR dressed by the spin excitations of the remaining electrons. The spectrum is interpreted in terms of the appearance of a topological phase associated with an effective gauge field piercing through the ring. We show that the maximally spin-polarized (S =5 /2 ) and maximally spin-depolarized (S =1 /2 ) states are the lowest energy, orbitally nondegenerate, states. We discuss the evolution of the phase diagram and level crossings as interactions are switched off and the ground state becomes spin nondegenerate but orbitally degenerate S =1 /2 . We present a theory of optical absorption spectra and show that the evolution of the ground and excited states, level crossings, and presence of artificial gauge can be detected optically.

  16. Stereo Image Reversible Watermarking for Authentication

    Science.gov (United States)

    Luo, Ting; Jiang, Gangyi; Peng, Zongju; Shao, Feng; Yu, Mei

    2015-03-01

    To authenticate stereo image, this paper proposes a stereo image reversible watermarking method for three dimensional television systems. The proposed method can recover the original stereo image without any distortion if stereo image is not tampered. Otherwise, it can authenticate stereo image with the capability of locating tamper. Difference expansion is used to embed authentication bits reversibly into each block for locating tamper. Pixel pairs without resulting in overflow/underflow after expansion are chosen as candidates of embedding locations. In order to avoid transmit big size of embedding location map, the same embedding locations for each block are decided in advance, which adaptively determines the block size. Moreover, in order to resist collage attack, authentication bits generated from each block embedded into its mapping blocks, so that authentication of each block is not independent. Experimental results demonstrate that stereo image can be totally recovered if watermarked stereo image is not modified. Moreover, it proves suitability and stability of the proposed method for tamper location with relationships of stereo images.

  17. MODEL PSEUDOPOTENTIAL OF THE ELECTRON - NEGATIVE ION INTERACTION

    Directory of Open Access Journals (Sweden)

    Yu.Rudavskii

    2003-01-01

    Full Text Available Generalization of the Anderson model to describe the states of electronegative impurities in liquid-metal alloys is the main aim of the present paper. The effects of the random inner field on the charge impurity states is accounted for selfconsistently. Qualitative and quantitative estimation of hamiltonian parameters has been carried out. The limits of the proposed model applicability to a description of real systems are considered. Especially, the case of the oxygen impurity in liquid sodium is studied. The modelling of the proper electron-ionic interaction potential is the main goal of the paper. The parameters of the proposed pseudopotential are analyzed in detail. The comparison with other model potentials have been carried out. Resistivity of liquid sodium containing the oxygen impurities is calculated with utilizing the form-factor of the proposed model potential. Dependence of the resistivity on impurity concentration and on the charge states is received.

  18. Transmission zero in a quantum dot with strong electron-electron interaction: Perturbative conductance calculations

    Science.gov (United States)

    Kim, Sejoong; Lee, Hyun-Woo

    2006-05-01

    A pioneering experiment [E. Schuster, E. Buks, M. Heiblum, D. Mahalu, V. Umansky, and Hadas Shtrikman, Nature 385, 417 (1997)] reported the measurement of the transmission phase of an electron traversing a quantum dot and found the intriguing feature of a sudden phase drop in the conductance valleys. Based on the Friedel sum rule for a spinless effective one-dimensional system, it has been previously argued [H.-W. Lee, Phys. Rev. Lett. 82, 2358 (1999)] that the sudden phase drop should be accompanied by the vanishing of the transmission amplitude, or transmission zero. Here we address roles of strong electron-electron interactions on the electron transport through a two-level quantum dot where one level couples with the leads much more strongly than the other level does [P. G. Silvestrov and Y. Imry, Phys. Rev. Lett. 85, 2565 (2000)]. We perform a perturbative conductance calculation with an explicit account of large charging energy and verify that the resulting conductance exhibits transmission zero, in agreement with the analysis based on the Friedel sum rule.

  19. Practical intraoperative stereo camera calibration.

    Science.gov (United States)

    Pratt, Philip; Bergeles, Christos; Darzi, Ara; Yang, Guang-Zhong

    2014-01-01

    Many of the currently available stereo endoscopes employed during minimally invasive surgical procedures have shallow depths of field. Consequently, focus settings are adjusted from time to time in order to achieve the best view of the operative workspace. Invalidating any prior calibration procedure, this presents a significant problem for image guidance applications as they typically rely on the calibrated camera parameters for a variety of geometric tasks, including triangulation, registration and scene reconstruction. While recalibration can be performed intraoperatively, this invariably results in a major disruption to workflow, and can be seen to represent a genuine barrier to the widespread adoption of image guidance technologies. The novel solution described herein constructs a model of the stereo endoscope across the continuum of focus settings, thereby reducing the number of degrees of freedom to one, such that a single view of reference geometry will determine the calibration uniquely. No special hardware or access to proprietary interfaces is required, and the method is ready for evaluation during human cases. A thorough quantitative analysis indicates that the resulting intrinsic and extrinsic parameters lead to calibrations as accurate as those derived from multiple pattern views.

  20. Near real-time stereo vision system

    Science.gov (United States)

    Anderson, Charles H. (Inventor); Matthies, Larry H. (Inventor)

    1993-01-01

    The apparatus for a near real-time stereo vision system for use with a robotic vehicle is described. The system is comprised of two cameras mounted on three-axis rotation platforms, image-processing boards, a CPU, and specialized stereo vision algorithms. Bandpass-filtered image pyramids are computed, stereo matching is performed by least-squares correlation, and confidence ranges are estimated by means of Bayes' theorem. In particular, Laplacian image pyramids are built and disparity maps are produced from the 60 x 64 level of the pyramids at rates of up to 2 seconds per image pair. The first autonomous cross-country robotic traverses (of up to 100 meters) have been achieved using the stereo vision system of the present invention with all computing done onboard the vehicle. The overall approach disclosed herein provides a unifying paradigm for practical domain-independent stereo ranging.

  1. Improved Stereo Matching With Boosting Method

    Directory of Open Access Journals (Sweden)

    Shiny B

    2015-06-01

    Full Text Available Abstract This paper presents an approach based on classification for improving the accuracy of stereo matching methods. We propose this method for occlusion handling. This work employs classification of pixels for finding the erroneous disparity values. Due to the wide applications of disparity map in 3D television medical imaging etc the accuracy of disparity map has high significance. An initial disparity map is obtained using local or global stereo matching methods from the input stereo image pair. The various features for classification are computed from the input stereo image pair and the obtained disparity map. Then the computed feature vector is used for classification of pixels by using GentleBoost as the classification method. The erroneous disparity values in the disparity map found by classification are corrected through a completion stage or filling stage. A performance evaluation of stereo matching using AdaBoostM1 RUSBoost Neural networks and GentleBoost is performed.

  2. Transmission Probability for Interacting Electrons Connected to Reservoirs

    Science.gov (United States)

    Oguri, Akira

    2001-09-01

    Transport through small interacting systems connected to noninteracting leads is studied based on the Kubo formalism using a Éliashberg theory of the analytic properties of the vertex part. The transmission probability, by which the conductance is expressed as g = (2e2/h) \\int dɛ (- \\partial f / \\partial ɛ) \\mathcal{T}(ɛ), is introduced for interacting electrons. Here f(ɛ) is the Fermi function, and the transmission probability T(ɛ) is defined in terms of a current vertex or a three-point correlation function. We apply this formulation to a series of Anderson impurities of size N (=1, 2, 3, 4), and calculate T(ɛ) using the order U2 self-energy and current vertex which satisfy a generalized Ward identity. The results show that T(ɛ) has much information about the excitation spectrum: T(ɛ) has two broad peaks of the upper and lower Hubbard bands in addition to N resonant peaks which have direct correspondence with the noninteracting spectrum. The peak structures disappear at high temperatures.

  3. Observation of Relativistic Electron Microbursts in Conjunction with Intense Radiation Belt Whistler-Mode Waves

    Science.gov (United States)

    Kersten, K.; Cattell, C. A.; Breneman, A.; Goetz, K.; Kellogg, P. J.; Wygant, J. R.; Wilson, L. B., III; Blake, J. B.; Looper, M. D.; Roth, I.

    2011-01-01

    We present multi-satellite observations of large amplitude radiation belt whistler-mode waves and relativistic electron precipitation. On separate occasions during the Wind petal orbits and STEREO phasing orbits, Wind and STEREO recorded intense whistler-mode waves in the outer nightside equatorial radiation belt with peak-to-peak amplitudes exceeding 300 mV/m. During these intervals of intense wave activity, SAMPEX recorded relativistic electron microbursts in near magnetic conjunction with Wind and STEREO. This evidence of microburst precipitation occurring at the same time and at nearly the same magnetic local time and L-shell with a bursty temporal structure similar to that of the observed large amplitude wave packets suggests a causal connection between the two phenomena. Simulation studies corroborate this idea, showing that nonlinear wave.particle interactions may result in rapid energization and scattering on timescales comparable to those of the impulsive relativistic electron precipitation.

  4. Effect of electron-electron interaction on the magnetic moment and susceptibility of a parabolic GaAs quantum dot

    Science.gov (United States)

    Boda, Aalu; Kumar, D. Sanjeev; Sankar, I. V.; Chatterjee, Ashok

    2016-11-01

    The problem of a parabolically confined two-dimensional semiconductor GaAs quantum dot with two interacting electrons in the presence of an external magnetic field and the spin-Zeeman interaction is studied using a method of numerical diagonalization. The energy spectrum is calculated as a function of the magnetic field. The magnetic moment (M) and the magnetic susceptibility (χ) show zero temperature diamagnetic peaks due to the exchange induced singlet-triplet transitions. The position and the number of these peaks depend both on the confinement strength of the quantum dot and the strength of the electron-electron interaction (β) .

  5. HRSC: High resolution stereo camera

    Science.gov (United States)

    Neukum, G.; Jaumann, R.; Basilevsky, A.T.; Dumke, A.; Van Gasselt, S.; Giese, B.; Hauber, E.; Head, J. W.; Heipke, C.; Hoekzema, N.; Hoffmann, H.; Greeley, R.; Gwinner, K.; Kirk, R.; Markiewicz, W.; McCord, T.B.; Michael, G.; Muller, Jan-Peter; Murray, J.B.; Oberst, J.; Pinet, P.; Pischel, R.; Roatsch, T.; Scholten, F.; Willner, K.

    2009-01-01

    The High Resolution Stereo Camera (HRSC) on Mars Express has delivered a wealth of image data, amounting to over 2.5 TB from the start of the mapping phase in January 2004 to September 2008. In that time, more than a third of Mars was covered at a resolution of 10-20 m/pixel in stereo and colour. After five years in orbit, HRSC is still in excellent shape, and it could continue to operate for many more years. HRSC has proven its ability to close the gap between the low-resolution Viking image data and the high-resolution Mars Orbiter Camera images, leading to a global picture of the geological evolution of Mars that is now much clearer than ever before. Derived highest-resolution terrain model data have closed major gaps and provided an unprecedented insight into the shape of the surface, which is paramount not only for surface analysis and geological interpretation, but also for combination with and analysis of data from other instruments, as well as in planning for future missions. This chapter presents the scientific output from data analysis and highlevel data processing, complemented by a summary of how the experiment is conducted by the HRSC team members working in geoscience, atmospheric science, photogrammetry and spectrophotometry. Many of these contributions have been or will be published in peer-reviewed journals and special issues. They form a cross-section of the scientific output, either by summarising the new geoscientific picture of Mars provided by HRSC or by detailing some of the topics of data analysis concerning photogrammetry, cartography and spectral data analysis.

  6. Energy Quantization and Probability Density of Electron in Intense-Field-Atom Interactions

    Institute of Scientific and Technical Information of China (English)

    敖淑艳; 程太旺; 李晓峰; 吴令安; 付盘铭

    2003-01-01

    We find that, due to the quantum correlation between the electron and the field, the electronic energy becomes quantized also, manifesting the particle aspect of light in the electron-light interaction. The probability amplitude of finding electron with a given energy is given by a generalized Bessel function, which can be represented as a coherent superposition of contributions from a few electronic quantum trajectories. This concept is illustrated by comparing the spectral density of the electron with the laser assisted recombination spectrum.

  7. Stereo vision with distance and gradient recognition

    Science.gov (United States)

    Kim, Soo-Hyun; Kang, Suk-Bum; Yang, Tae-Kyu

    2007-12-01

    Robot vision technology is needed for the stable walking, object recognition and the movement to the target spot. By some sensors which use infrared rays and ultrasonic, robot can overcome the urgent state or dangerous time. But stereo vision of three dimensional space would make robot have powerful artificial intelligence. In this paper we consider about the stereo vision for stable and correct movement of a biped robot. When a robot confront with an inclination plane or steps, particular algorithms are needed to go on without failure. This study developed the recognition algorithm of distance and gradient of environment by stereo matching process.

  8. Irregular Aharonov-Bohm effect for interacting electrons in a ZnO quantum ring.

    Science.gov (United States)

    Chakraborty, Tapash; Manaselyan, Aram; Barseghyan, Manuk

    2017-02-22

    The electronic states and optical transitions of a ZnO quantum ring containing few interacting electrons in an applied magnetic field are found to be very different from those in a conventional semiconductor system, such as a GaAs ring. The strong Zeeman interaction and the Coulomb interaction of the ZnO system, two important characteristics of the electron system in ZnO, exert a profound influence on the electron states and on the optical properties of the ring. In particular, our results indicate that the Aharonov-Bohm (AB) effect in a ZnO quantum ring strongly depends on the electron number. In fact, for two electrons in the ZnO ring, the AB oscillations become aperiodic, while for three electrons (interacting) the AB oscillations completely disappear. Therefore, unlike in conventional quantum ring topology, here the AB effect (and the resulting persistent current) can be controlled by varying the electron number.

  9. Irregular Aharonov-Bohm effect for interacting electrons in a ZnO quantum ring

    Science.gov (United States)

    Chakraborty, Tapash; Manaselyan, Aram; Barseghyan, Manuk

    2017-02-01

    The electronic states and optical transitions of a ZnO quantum ring containing few interacting electrons in an applied magnetic field are found to be very different from those in a conventional semiconductor system, such as a GaAs ring. The strong Zeeman interaction and the Coulomb interaction of the ZnO system, two important characteristics of the electron system in ZnO, exert a profound influence on the electron states and on the optical properties of the ring. In particular, our results indicate that the Aharonov-Bohm (AB) effect in a ZnO quantum ring strongly depends on the electron number. In fact, for two electrons in the ZnO ring, the AB oscillations become aperiodic, while for three electrons (interacting) the AB oscillations completely disappear. Therefore, unlike in conventional quantum ring topology, here the AB effect (and the resulting persistent current) can be controlled by varying the electron number.

  10. Theory of Auger-electron and appearance-potential spectroscopy for interacting valence-band electrons

    Science.gov (United States)

    Nolting, W.; Geipel, G.; Ertl, K.

    1991-12-01

    A theory of Auger-electron spectroscopy (AES) and appearance-potential spectroscopy (APS) is presented for interacting electrons in a nondegenerate energy band, described within the framework of the Hubbard model. Both types of spectroscopy are based on the same two-particle spectral density. A diagrammatic vertex-correction method (Matsubara formalism) is used to express this function in terms of the one-particle spectral density. The latter is approximately determined for arbitrary temperature T, arbitrary coupling strength U/W (U, the intra-atomic Coulomb matrix element; W, the width of the ``free'' Bloch band), and arbitrary band occupations n (0QDOS) in relation to the Bloch density of states (BDOS), where, however, spontaneous magnetic order is excluded, irrespective of the band filling n. The AE (AP) spectra consist of only one structure a few eV wide (``bandlike'') which is strongly n dependent, but only slightly T dependent, being rather well approximated by a simple self-convolution of the occupied (unoccupied) QDOS. For strongly correlated electrons the Bloch band splits into two quasiparticle subbands. This leads for n1. For sufficiently strong correlations U/W additional satellites appear that refer to situations where the two excited quasiparticles (quasiholes) propagate as tightly bound pairs through the lattice without being scattered by other charge carriers. As soon as the satellite splits off from the bandlike part of the spectrum, it takes almost the full spectral weight, conveying the impression of an ``atomiclike'' AE (AP) line shape. The satellite has almost exactly the structure of the free BDOS. If the particle density n as well as the hole density 2-n exceed certain critical values determined by U/W and the BDOS ρ0(E), spontaneous ferromagnetism becomes possible in the strongly correlated electron band. The magnetic phase transition gives rise to a distinctive T dependence for the QDOS and hence also for the AE and AP line shapes

  11. Crossover of electron-electron interaction effect in Sn-doped indium oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yu-Jie; Gao, Kuang-Hong; Li, Zhi-Qing, E-mail: zhiqingli@tju.edu.cn [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, Tianjin University, Tianjin 300072 (China)

    2015-03-09

    We systematically study the structures and electrical transport properties of a series of Sn-doped indium oxide (ITO) films with thickness t ranging from ∼5 to ∼53 nm. Scanning electron microscopy and x-ray diffraction results indicate that the t ≲ 16.8 nm films are polycrystalline, while those t ≳ 26.7 nm films are epitaxially grown along [100] direction. For the epitaxial films, the Altshuler and Aronov electron-electron interaction (EEI) effect governs the temperature behaviors of the sheet conductance σ{sub □} at low temperatures, and the ratios of relative change of Hall coefficient ΔR{sub H}/R{sub H} to relative change of sheet resistance ΔR{sub □}/R{sub □} are ≈2, which is quantitatively consistent with Altshuler and Aronov EEI theory and seldom observed in other systems. For those polycrystalline films, both the sheet conductance and Hall coefficient vary linearly with logarithm of temperature below several tens Kelvin, which can be well described by the current EEI theories in granular metals. We extract the intergranular tunneling conductance of each film by comparing the σ{sub □}(T) data with the predication of EEI theories in granular metals. It is found that when the tunneling conductance is less than the conductance of a single indium tin oxide (ITO) grain, the ITO film reveals granular metal characteristics in transport properties; conversely, the film shows transport properties of homogeneous disordered conductors. Our results indicate that electrical transport measurement can not only reveal the underlying charge transport properties of the film but also be a powerful tool to detect the subtle homogeneity of the film.

  12. Flexible Hardware-Based Stereo Matching

    Directory of Open Access Journals (Sweden)

    2009-02-01

    Full Text Available To enable adaptive stereo vision for hardware-based embedded stereo vision systems, we propose a novel technique for implementing a flexible block size, disparity range, and frame rate. By reusing existing resources of a static architecture, rather than dynamic reconfiguration, our technique is compatible with application specific integrated circuit (ASIC as well as field programmable gate array (FPGA implementations. We present the corresponding block diagrams and their implementation in our hardware-based stereo matching architecture. Furthermore, we show the impact of flexible stereo matching on the generated disparity maps for the sum of absolute differences (SADs, rank, and census transform algorithms. Finally, we discuss the resource usage and achievable performance when synthesized for an Altera Stratix II FPGA.

  13. Flexible Hardware-Based Stereo Matching

    Directory of Open Access Journals (Sweden)

    Steininger Andreas

    2008-01-01

    Full Text Available Abstract To enable adaptive stereo vision for hardware-based embedded stereo vision systems, we propose a novel technique for implementing a flexible block size, disparity range, and frame rate. By reusing existing resources of a static architecture, rather than dynamic reconfiguration, our technique is compatible with application specific integrated circuit (ASIC as well as field programmable gate array (FPGA implementations. We present the corresponding block diagrams and their implementation in our hardware-based stereo matching architecture. Furthermore, we show the impact of flexible stereo matching on the generated disparity maps for the sum of absolute differences (SADs, rank, and census transform algorithms. Finally, we discuss the resource usage and achievable performance when synthesized for an Altera Stratix II FPGA.

  14. TISSUE INTERACTIONS WITH DERMAL SHEEP COLLAGEN IMPLANTS - A TRANSMISSION ELECTRON-MICROSCOPIC EVALUATION

    NARCIS (Netherlands)

    VANWACHEM, PB; VANLUYN, MJA; DAMINK, LO; FEIJEN, J; NIEUWENHUIS, P

    1991-01-01

    Tissue interactions with discs of dermal sheep collagen (DSC), subcutaneously implanted in rats, were evaluated using transmission electron microscopy. DSC cross-linked with hexamethylenediisocyanate (HDSC) had already been tested previously. In the present study, we compared tissue interactions of

  15. Noncovalent Intermolecular Interactions in Organic Electronic Materials: Implications for the Molecular Packing vs Electronic Properties of Acenes

    KAUST Repository

    Sutton, Christopher

    2015-10-30

    Noncovalent intermolecular interactions, which can be tuned through the toolbox of synthetic chemistry, determine not only the molecular packing but also the resulting electronic, optical, and mechanical properties of materials derived from π-conjugated molecules, oligomers, and polymers. Here, we provide an overview of the theoretical underpinnings of noncovalent intermolecular interactions and briefly discuss the computational chemistry approaches used to understand the magnitude of these interactions. These methodologies are then exploited to illustrate how noncovalent intermolecular interactions impact important electronic properties-such as the electronic coupling between adjacent molecules, a key parameter for charge-carrier transport-through a comparison between the prototype organic semiconductor pentacene with a series of N-substituted heteropentacenes. Incorporating an understanding of these interactions into the design of organic semiconductors can assist in developing novel materials systems from this fascinating molecular class. © 2015 American Chemical Society.

  16. Electron-phonon interaction dressed by electronic correlations near charge ordering. Possible implications for cobaltates

    Energy Technology Data Exchange (ETDEWEB)

    Foussats, A [Facultad de Ciencias Exactas, Ingenieria y Agrimensura and Instituto de Fisica Rosario (UNR-CONICET), Avenida Pellegrini 250-2000 Rosario (Argentina); Greco, A [Facultad de Ciencias Exactas, Ingenieria y Agrimensura and Instituto de Fisica Rosario (UNR-CONICET), Avenida Pellegrini 250-2000 Rosario (Argentina); Bejas, M [Facultad de Ciencias Exactas, Ingenieria y Agrimensura and Instituto de Fisica Rosario (UNR-CONICET), Avenida Pellegrini 250-2000 Rosario (Argentina); Muramatsu, A [Institut fuer Theoretische Physik III, Universitaet Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart (Germany)

    2006-12-20

    We consider possible routes to superconductivity on the basis of the t-J-V model plus phonons on the triangular lattice. We studied the stability conditions for the homogeneous Fermi liquid (HFL) phase against different broken symmetry phases. Besides the {radical}3 x{radical}3 CDW phase, triggered by the nearest-neighbour Coulomb interaction V, we have found that the HFL is unstable, at very low doping, against a bond-ordered phase due to J. We also discuss the occurrence of phase separation at low doping and V. The interplay between the electron-phonon interaction and correlations near the {radical}3 x{radical}3 CDW leads to superconductivity in the unconventional next-nearest-neighbour f-wave (NNN-f) channel with a dome shape for T{sub c} around x{approx}0.35, and with values of a few kelvin. Near the bond-ordered phase at low doping we found tendencies to superconductivity with d-wave symmetry for finite J and x<0.15. Possible implications for cobaltates are discussed.

  17. Effect of electron-electron interactions on Rashba-like and spin-split systems

    Science.gov (United States)

    Alexandradinata, A.; Hirsch, J. E.

    2010-11-01

    The role of electron-electron interactions is analyzed for Rashba-like and spin-split systems within a tight-binding single-band Hubbard model with on-site and all nearest-neighbor matrix elements of the Coulomb interaction. By Rashba-like systems we refer to the Dresselhaus and Rashba spin-orbit-coupled phases while spin-split systems have spin-up and spin-down Fermi surfaces shifted relative to each other. Both systems break parity but preserve time-reversal symmetry. They belong to a class of symmetry-breaking ground states that satisfy: (i) electron crystal momentum is a good quantum number, (ii) these states have no net magnetic moment, and (iii) their distribution of “polarized spin” in momentum space breaks the lattice symmetry. For all members of this class, the relevant Coulomb matrix elements are found to be nearest-neighbor exchange J , pair hopping J' , and nearest-neighbor repulsion V . These ground states lower their energy most effectively through J , hence we name them class J states. The competing effects of V-J' on the direct and exchange energies determine the relative stability of class J states. We show that the spin-split and Rashba-like phases are the most favored ground states within class J because they have the minimum anisotropy in polarized spin. We analyze these two states on a square lattice and find that the spin-split phase is always favored for near-empty bands; above a critical filling, we predict a transition from the paramagnetic to the Rashba-like phase at a critical J(Jc1) and a second transition from the Rashba-like to the spin-split state at Jc2>Jc1 . An energetic comparison with ferromagnetism highlights the importance of the role of V in the stability of class J states. We discuss the relevance of our results to (i) the α and β phases proposed by Wu and Zhang in the Fermi-liquid formalism and (ii) experimental observations of spin-orbit splitting in Au(111) surface states.

  18. Attractive electron-electron interactions at the LaAlO3/SrTiO3 Interface

    DEFF Research Database (Denmark)

    Prawiroatmodjo, Guenevere E D K

    state is found, and transport characteristics are described to originate from attractive electron-electron interactions that result in a negative effective charging energy U. Further, the excitation spectrum is explored and compared to calculations based on a single-orbital Anderson model with negative...

  19. Hot electrons generated by ultra-short pulse laser interacting with solid targets

    Institute of Scientific and Technical Information of China (English)

    陈黎明; 张杰; 李玉同; 梁天骄; 王龙; 魏志义; 江文勉

    2000-01-01

    Hot electrons produced by ultra-short pulse laser interacting with solid targets were studied systematically. When 800 nm, 8 × 1015 W/cm2 laser pulses interacted with solid targets, hot electron e-mission was found to be collimated in certain directions and the angular distribution of hot electrons depended on the energy absorption. The angular divergence of outgoing hot electrons was inversely proportional to the hot electron energy. The energy spectrum of hot electrons was found to be in a bi-Maxwellian distribution and the maximum energy was over 500 keV.

  20. Hot electrons generated by ultra-short pulse laser interacting with solid targets

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Hot electrons produced by ultra-short pulse laser interacting with solid targets were studied systematically. When 800 nm, 8×1015 W/cm2 laser pulses interacted with solid targets, hot electron emission was found to be collimated in certain directions and the angular distribution of hot electrons depended on the energy absorption. The angular divergence of outgoing hot electrons was inversely proportional to the hot electron energy. The energy spectrum of hot electrons was found to be in a bi-Maxwellian distribution and the maximum energy was over 500 keV.

  1. Single camera stereo using structure from motion

    Science.gov (United States)

    McBride, Jonah; Snorrason, Magnus; Goodsell, Thomas; Eaton, Ross; Stevens, Mark R.

    2005-05-01

    Mobile robot designers frequently look to computer vision to solve navigation, obstacle avoidance, and object detection problems such as those encountered in parking lot surveillance. Stereo reconstruction is a useful technique in this domain and can be done in two ways. The first requires a fixed stereo camera rig to provide two side-by-side images; the second uses a single camera in motion to provide the images. While stereo rigs can be accurately calibrated in advance, they rely on a fixed baseline distance between the two cameras. The advantage of a single-camera method is the flexibility to change the baseline distance to best match each scenario. This directly increases the robustness of the stereo algorithm and increases the effective range of the system. The challenge comes from accurately rectifying the images into an ideal stereo pair. Structure from motion (SFM) can be used to compute the camera motion between the two images, but its accuracy is limited and small errors can cause rectified images to be misaligned. We present a single-camera stereo system that incorporates a Levenberg-Marquardt minimization of rectification parameters to bring the rectified images into alignment.

  2. Digital elevation modelling using ASTER stereo imagery.

    Science.gov (United States)

    Forkuo, Eric Kwabena

    2010-04-01

    Digital elevation model (DEM) in recent times has become an integral part of national spatial data infrastructure of many countries world-wide due to its invaluable importance. Although DEMs are mostly generated from contours maps, stereo aerial photographs and air-borne and terrestrial laser scanning, the stereo interpretation and auto-correlation from satellite image stereo-pairs such as with SPOT, IRS, and relatively new ASTER imagery is also an effective means of producing DEM data. In this study, terrain elevation data were derived by applying photogrammetric process to ASTER stereo imagery. Also, the quality ofDEMs produced from ASTER stereo imagery was analysed by comparing it with DEM produced from topographic map at a scale of 1:50,000. While analyzing the vertical accuracy of the generated ASTER DEM, fifty ground control points were extracted from the map and overlaid on the DEM. Results indicate that a root-mean-square error in elevation of +/- 14 m was achieved with ASTER stereo image data of good quality. The horizontal accuracy obtained from the ground control points was 14.77, which is within the acceptable range of +/- 7m to +/- 25 m. The generated (15 m) DEM was compared with a 20m, 25m, and a 30 m pixel DEM to the original map. In all, the results proved that, the 15 m DEM conform to the original map DEM than the others. Overall, this analysis proves that, the generated digital terrain model, DEM is acceptable.

  3. Effective mass in bilayer graphene at low carrier densities: The role of potential disorder and electron-electron interaction

    Science.gov (United States)

    Li, J.; Tan, L. Z.; Zou, K.; Stabile, A. A.; Seiwell, D. J.; Watanabe, K.; Taniguchi, T.; Louie, Steven G.; Zhu, J.

    2016-10-01

    In a two-dimensional electron gas, the electron-electron interaction generally becomes stronger at lower carrier densities and renormalizes the Fermi-liquid parameters, such as the effective mass of carriers. We combine experiment and theory to study the effective masses of electrons and holes me* and mh* in bilayer graphene in the low carrier density regime on the order of 1 ×1011c m-2 . Measurements use temperature-dependent low-field Shubnikov-de Haas oscillations observed in high-mobility hexagonal boron nitride supported samples. We find that while me* follows a tight-binding description in the whole density range, mh* starts to drop rapidly below the tight-binding description at a carrier density of n =6 ×1011c m-2 and exhibits a strong suppression of 30% when n reaches 2 ×1011c m-2 . Contributions from the electron-electron interaction alone, evaluated using several different approximations, cannot explain the experimental trend. Instead, the effect of the potential fluctuation and the resulting electron-hole puddles play a crucial role. Calculations including both the electron-electron interaction and disorder effects explain the experimental data qualitatively and quantitatively. This Rapid Communication reveals an unusual disorder effect unique to two-dimensional semimetallic systems.

  4. Effects of Electron-Phonon Interaction on Linear and Nonlinear Optical Absorption in Cylindrical Quantum Wires

    Institute of Scientific and Technical Information of China (English)

    YU You-Bin

    2008-01-01

    The electron-phonon interaction influences on linear and nonlinear optical absorption in cylindrical quantum wires (CQW) with an infinite confining potential are investigated. The optical absorption coefficients are obtained by using the compact-density-matrix approach and iterative method, and the numerical results are presented for GaAs CQW. The results show that the electron-phonon interaction makes a distinct influence on optical absorption in CQW. The electron-phonon interaction on the wave functions of electron dominates the values of absorption coefficients and the correction of the electron-phonon effect on the energies of the electron makes the absorption peaks blue shift and become wider. Moreover, the electron-phonon interaction influence on optical absorption with an infinite confining potential is different from that with a finite confining potential.

  5. Beam-excited whistler waves at oblique propagation with relation to STEREO radiation belt observations

    Directory of Open Access Journals (Sweden)

    K. Sauer

    2010-06-01

    Full Text Available Isotropic electron beams are considered to explain the excitation of whistler waves which have been observed by the STEREO satellite in the Earth's radiation belt. Aside from their large amplitudes (~240 mV/m, another main signature is the strongly inclined propagation direction relative to the ambient magnetic field. Electron temperature anisotropy with Te⊥>Te||, which preferentially generates parallel propagating whistler waves, can be excluded as a free energy source. The instability arises due to the interaction of the Doppler-shifted cyclotron mode ω=−Ωe+kVbcosθ with the whistler mode in the wave number range of kce≤1 (θ is the propagation angle with respect to the background magnetic field direction, ωe is the electron plasma frequency and Ωe the electron cyclotron frequency. Fluid and kinetic dispersion analysis have been used to calculate the growth rate of the beam-excited whistlers including the most important parameter dependencies. One is the beam velocity (Vb which, for instability, has to be larger than about 2VAe, where VAe is the electron Alfvén speed. With increasing VAe the propagation angle (θ of the fastest growing whistler waves shifts from θ~20° for Vb=2VAe to θ~80° for Vb=5VAe. The growth rate is reduced by finite electron temperatures and disappears if the electron plasma beta (βe exceeds βe~0.2. In addition, Gendrin modes (kce≈1 are analyzed to determine the conditions under which stationary nonlinear waves (whistler oscillitons can exist. The corresponding spatial wave profiles are calculated using the full nonlinear fluid approach. The results are compared with the STEREO satellite observations.

  6. Parity-violating electric-dipole transitions in helium induced by the electron-electron neutral weak interaction

    Energy Technology Data Exchange (ETDEWEB)

    Esteve, J.G.; Morales, A.; Morales, J.; Nuez-Lagos, R.; Pacheco, A.F.

    1984-04-01

    The parity-violating E1 transitions between the n = 2 levels of atomic helium, induced by the electron-electron neutral weak interaction have been computed by using Coulomb-type wave functions and (up to 84 parameter) Hylleraas wave functions. The parity-violating matrix elements turn out to be of the same order of magnitude as those due to the electron-nucleus weak interaction, thus allowing one to conclude that the relative importance of both effects is to be traced to their corresponding effective coupling constants.

  7. Pengukuran Jarak Berbasiskan Stereo Vision

    Directory of Open Access Journals (Sweden)

    Iman Herwidiana Kartowisastro

    2010-12-01

    Full Text Available Measuring distance from an object can be conducted in a variety of ways, including by making use of distance measuring sensors such as ultrasonic sensors, or using the approach based vision system. This last mode has advantages in terms of flexibility, namely a monitored object has relatively no restrictions characteristic of the materials used at the same time it also has its own difficulties associated with object orientation and state of the room where the object is located. To overcome this problem, so this study examines the possibility of using stereo vision to measure the distance to an object. The system was developed starting from image extraction, information extraction characteristics of the objects contained in the image and visual distance measurement process with 2 separate cameras placed in a distance of 70 cm. The measurement object can be in the range of 50 cm - 130 cm with a percentage error of 5:53%. Lighting conditions (homogeneity and intensity has a great influence on the accuracy of the measurement results. 

  8. Quantifying electronic band interactions in van der Waals materials using angle-resolved reflected-electron spectroscopy

    Science.gov (United States)

    Jobst, Johannes; van der Torren, Alexander J. H.; Krasovskii, Eugene E.; Balgley, Jesse; Dean, Cory R.; Tromp, Rudolf M.; van der Molen, Sense Jan

    2016-11-01

    High electron mobility is one of graphene's key properties, exploited for applications and fundamental research alike. Highest mobility values are found in heterostructures of graphene and hexagonal boron nitride, which consequently are widely used. However, surprisingly little is known about the interaction between the electronic states of these layered systems. Rather pragmatically, it is assumed that these do not couple significantly. Here we study the unoccupied band structure of graphite, boron nitride and their heterostructures using angle-resolved reflected-electron spectroscopy. We demonstrate that graphene and boron nitride bands do not interact over a wide energy range, despite their very similar dispersions. The method we use can be generally applied to study interactions in van der Waals systems, that is, artificial stacks of layered materials. With this we can quantitatively understand the `chemistry of layers' by which novel materials are created via electronic coupling between the layers they are composed of.

  9. Interactivity between protégés and scientists in an electronic mentoring program

    DEFF Research Database (Denmark)

    Bonnett, Cara; Wildemuth, Barbara M.; Sonnenwald, Diane H.

    2006-01-01

    in an electronic mentoring program. This report analyzes the interactivity between pairs of corporate research scientists (mentors) and university biology students (protégés) during two consecutive implementations of an electronic mentoring program. The frequency and structure of the interactions within each pair...

  10. Electronic voting to encourage interactive lectures: a randomised trial

    Science.gov (United States)

    2007-01-01

    Background Electronic Voting Systems have been used for education in a variety of disciplines. Outcomes from these studies have been mixed. Because results from these studies have been mixed, we examined whether an EVS system could enhance a lecture's effect on educational outcomes. Methods A cohort of 127 Year 5 medical students at the University of Adelaide was stratified by gender, residency status and academic record then randomised into 2 groups of 64 and 63 students. Each group received consecutive 40-minute lectures on two clinical topics. One group received the EVS for both topics. The other group received traditional teaching only. Evaluation was undertaken with two, 15-question multiple-choice questionnaires (MCQ) assessing knowledge and problem solving and undertaken as a written paper immediately before and after the lectures and repeated online 8–12 weeks later. Standardised institutional student questionnaires were completed for each lecture and independent observers assessed student behaviour during the lectures. Lecturer's opinions were assessed by a questionnaire developed for this study. Results Two-thirds of students randomised to EVS and 59% of students randomised to traditional lectures attended. One-half of the students in the EVS group and 41% in the traditional group completed all questionnaires. There was no difference in MCQ scores between EVS and traditional lectures (p = 0.785). The cervical cancer lectures showed higher student ranking in favour of EVS in all parameters. The breast cancer lectures showed higher ranking in favour of traditional lectures in 5 of 7 parameters (p lecturer-students interactions were increased in the EVS lecture for one lecturer and reduced for the other. Both lecturers felt that the EVS lectures were difficult to prepare, that they were able to keep to time in the traditional lectures, that the educational value of both lecture styles was similar, and that they were neutral-to-slightly favourably disposed

  11. Magnetic interactions and electronic structure of Ni–Mn–In

    Energy Technology Data Exchange (ETDEWEB)

    D' Souza, Sunil Wilfred [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001, Madhya Pradesh (India); Chakrabarti, Aparna [Raja Ramanna Centre for Advanced Technology, Indore 452013, Madhya Pradesh (India); Barman, Sudipta Roy, E-mail: barmansr@gmail.com [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001, Madhya Pradesh (India)

    2016-04-15

    Highlights: • The ground state of Ni{sub 2}Mn{sub 1.4}In{sub 0.6} is ferromagnetic. • The magnetic moments of Ni–Mn–In are in good agreement with the magnetization measurements. • Exchange coupling parameters exhibit a strong competition between ferromagnetic and antiferromagnetic configurations. • Jahn–Teller splitting of the Ni 3d e{sub g} states drives the martensite transformation. - Abstract: The electronic structure and magnetic properties of a magnetic shape memory alloy Ni–Mn–In have been studied using spin polarized fully relativistic Korringa–Kohn–Rostoker (SPRKKR) method. The total energy calculations with different starting magnetic spin configurations show that the ground state of Ni{sub 2}Mn{sub 1.4}In{sub 0.6} is ferromagnetic. The spin and orbital magnetic moments of Ni{sub 2}Mn{sub 1.4}In{sub 0.6} and Ni{sub 2}MnIn are in good agreement with the magnetization measurements. The exchange coupling parameters of the different sublattice interactions exhibit a strong competition between ferromagnetic and antiferromagnetic configurations, due to the substitution of excess Mn atoms at the In site in Ni{sub 2}Mn{sub 1.4}In{sub 0.6}. The Curie temperature of Ni{sub 2}MnIn, calculated under a mean field approximation, is found to be in relatively good agreement with the experimental values. While Ni{sub 2}MnIn does not undergo martensite transition, it is shown that a Jahn–Teller splitting of the Ni 3d e{sub g} states plays an important role in driving the martensite transformation in Ni{sub 2}Mn{sub 1.4}In{sub 0.6}. We find that both the calculated ultra-violet photoemission spectra and the inverse photoemission spectra are in good agreement with the existing experimental data.

  12. Electronic voting to encourage interactive lectures: a randomised trial.

    Science.gov (United States)

    Duggan, Paul M; Palmer, Edward; Devitt, Peter

    2007-07-27

    Electronic Voting Systems have been used for education in a variety of disciplines. Outcomes from these studies have been mixed. Because results from these studies have been mixed, we examined whether an EVS system could enhance a lecture's effect on educational outcomes. A cohort of 127 Year 5 medical students at the University of Adelaide was stratified by gender, residency status and academic record then randomised into 2 groups of 64 and 63 students. Each group received consecutive 40-minute lectures on two clinical topics. One group received the EVS for both topics. The other group received traditional teaching only. Evaluation was undertaken with two, 15-question multiple-choice questionnaires (MCQ) assessing knowledge and problem solving and undertaken as a written paper immediately before and after the lectures and repeated online 8-12 weeks later. Standardised institutional student questionnaires were completed for each lecture and independent observers assessed student behaviour during the lectures. Lecturer's opinions were assessed by a questionnaire developed for this study. Two-thirds of students randomised to EVS and 59% of students randomised to traditional lectures attended. One-half of the students in the EVS group and 41% in the traditional group completed all questionnaires. There was no difference in MCQ scores between EVS and traditional lectures (p = 0.785). The cervical cancer lectures showed higher student ranking in favour of EVS in all parameters. The breast cancer lectures showed higher ranking in favour of traditional lectures in 5 of 7 parameters (p higher-order lecturer-students interactions were increased in the EVS lecture for one lecturer and reduced for the other. Both lecturers felt that the EVS lectures were difficult to prepare, that they were able to keep to time in the traditional lectures, that the educational value of both lecture styles was similar, and that they were neutral-to-slightly favourably disposed to continue with

  13. Investigation of electron heating in laser-plasma interaction

    Directory of Open Access Journals (Sweden)

    A Parvazian

    2013-03-01

    Full Text Available  In this paper, stimulated Raman scattering (SRS and electron heating in laser plasma propagating along the plasma fusion is investigated by particle-in cell simulation. Applying an external magnetic field to plasma, production of whistler waves and electron heating associated with whistler waves in the direction perpendicular to external magnetic field was observed in this simulation. The plasma waves with low phase velocities, generated in backward-SRS and dominateing initially in time and space, accelerated the backward electrons by trapping them. Then these electrons promoted to higher energies by the forward-SRS plasma waves with high phase velocities. This tow-stage electron acceleration is more efficient due to the coexistence of these two instabilities.

  14. An Electron Bunch Compressor Based on an FEL Interaction in the Far Infra Red

    OpenAIRE

    Gaupp, Andreas

    2013-01-01

    In this note an electron bunch compressor is proposed based on FEL type interaction of the electron bunch with far infrared (FIR) radiation. This mechanism maintains phase space density and thus requires a high quality electron beam to produce bunches of the length of a few ten micrometer.

  15. Playing with Technology: Mother-Toddler Interaction Scores Lower during Play with Electronic Toys

    Science.gov (United States)

    Wooldridge, Michaela B.; Shapka, Jennifer

    2012-01-01

    To investigate play with electronic toys (battery-operated or digital), 25 mother-toddler (16-24 months old) dyads were videotaped in their homes playing with sets of age-appropriate electronic and non-electronic toys for approximately 10 min each. Parent-child interactions were coded from recorded segments of both of the play conditions using the…

  16. 3D Stereo Visualization for Mobile Robot Tele-Guide

    DEFF Research Database (Denmark)

    Livatino, Salvatore

    2006-01-01

    learning and decision performance. Works in the literature have demonstrated how stereo vision contributes to improve perception of some depth cues often for abstract tasks, while little can be found about the advantages of stereoscopic visualization in mobile robot tele-guide applications. This work...... technologies. In particular, experiments were carried out on different virtual reality (VR) systems having different characteristics both in terms of sense of presence and interaction capabilities provided to a user, as well as cost and portability. Results from a set of test trials ran on five VR systems...

  17. How light modifies the electron–electron interaction under extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hinschberger, Y. [Instituto de Física dos Materiais da Universidade do Porto, Departamento de Física e Astronomia, Rua do campo Alegre, 687, 4169-007 Porto (Portugal); Hervieux, P.-A., E-mail: hervieux@ipcms.u-strasbg.fr [Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS and Université de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2 (France)

    2015-10-02

    In the domain of extreme light–matter interactions, we show that the electron–electron interaction can be modified coherently by the electric field of the light. The latter play the role of a third partner not only acting on the electrons individually but also on their mutual interaction. By using an original formalism based on the Foldy–Wouthuysen transformation and applied to the Dirac–Breit Hamiltonian in the presence of a time-dependent electromagnetic field, we obtain analytical expressions of new three-body light–matter interactions. - Highlights: • A time-dependent electromagnetic field can modify the electronic interaction. • Analytical expressions of this three-body light matter interactions are presented. • Effects can be evaluated with the amplitude of the laser and electronic distance.

  18. Test beam results of a stereo preshower integrated in the liquid argon accordion calorimeter

    CERN Document Server

    Davis, R; Greenious, G; Kitching, P; Olsen, B; Pinfold, James L; Rodning, N L; Boos, E; Zhautykov, B O; Aubert, Bernard; Bazan, A; Beaugiraud, B; Boniface, J; Colas, Jacques; Eynard, G; Jézéquel, S; Le Flour, T; Linossier, O; Nicoleau, S; Sauvage, G; Thion, J; Van den Plas, D; Wingerter-Seez, I; Zitoun, R; Zolnierowski, Y; Chmeissani, M; Fernández, E; Garrido, L; Martínez, M; Padilla, C; Citterio, M; Gordon, H A; Lissauer, D; Ma, H; Makowiecki, D S; Radeka, V; Rahm, David Charles; Rescia, S; Stephani, D; Takai, H; Baisin, L; Berset, J C; Chevalley, J L; Gianotti, F; Gildemeister, O; Marin, C P; Nessi, Marzio; Poggioli, Luc; Richter, W; Vuillemin, V; Baze, J M; Delagnes, E; Gosset, L G; Lavocat, P; Lottin, J P; Mansoulié, B; Meyer, J P; Renardy, J F; Schwindling, J; Simion, S; Taguet, J P; Teiger, J; Walter, C; Collot, J; de Saintignon, P; Hostachy, J Y; Mahout, G; Barreiro, F; Del Peso, J; García, J; Hervás, L; Labarga, L; Romero, P; Scheel, C V; Chekhtman, A; Cousinou, M C; Dargent, P; Dinkespiler, B; Etienne, F; Fassnacht, P; Fouchez, D; Martin, L; Miotto, A; Monnier, E; Nagy, E; Olivetto, C; Tisserant, S; Battistoni, G; Camin, D V; Cavalli, D; Costa, G; Cozzi, L; Fedyakin, N N; Ferrari, A; Mandelli, L; Mazzanti, M; Perini, L; Resconi, S; Sala, P R; Beaudoin, G; Depommier, P; León-Florián, E; Leroy, C; Roy, P; Augé, E; Breton, D; Chase, Robert L; Chollet, J C; de La Taille, C; Fayard, Louis; Fournier, D; González, J; Hrisoho, A T; Jacquier, Y; Merkel, B; Nikolic, I A; Noppe, J M; Parrour, G; Pétroff, P; Puzo, P; Richer, J P; Schaffer, A C; Seguin-Moreau, N; Serin, L; Tisserand, V; Veillet, J J; Vichou, I; Canton, B; David, J; Genat, J F; Imbault, D; Le Dortz, O; Savoy-Navarro, Aurore; Schwemling, P; Eek, L O; Lund-Jensen, B; Söderqvist, J; Astbury, Alan; Keeler, Richard K; Lefebvre, M; Robertson, S; White, J

    1998-01-01

    This paper describes the construction of an integrated preshower within the RD3 liquid argon accordion calorimeter. It has a stereo view which enables the measurement of two transverse coordinates. The prototype was tested at CERN with electrons, photons and muons to validate its capability to work at LHC ( Energy resolution, impact point resolution, angular resolution, $\\pi^o$/$\\gamma$ rejection ).

  19. Stereo-vision-based perception capabilities developed during the Robotics Collaborative Technology Alliances program

    Science.gov (United States)

    Rankin, Arturo; Bajracharya, Max; Huertas, Andres; Howard, Andrew; Moghaddam, Baback; Brennan, Shane; Ansar, Adnan; Tang, Benyang; Turmon, Michael; Matthies, Larry

    2010-04-01

    The Robotics Collaborative Technology Alliances (RCTA) program, which ran from 2001 to 2009, was funded by the U.S. Army Research Laboratory and managed by General Dynamics Robotic Systems. The alliance brought together a team of government, industrial, and academic institutions to address research and development required to enable the deployment of future military unmanned ground vehicle systems ranging in size from man-portables to ground combat vehicles. Under RCTA, three technology areas critical to the development of future autonomous unmanned systems were addressed: advanced perception, intelligent control architectures and tactical behaviors, and human-robot interaction. The Jet Propulsion Laboratory (JPL) participated as a member for the entire program, working four tasks in the advanced perception technology area: stereo improvements, terrain classification, pedestrian detection in dynamic environments, and long range terrain classification. Under the stereo task, significant improvements were made to the quality of stereo range data used as a front end to the other three tasks. Under the terrain classification task, a multi-cue water detector was developed that fuses cues from color, texture, and stereo range data, and three standalone water detectors were developed based on sky reflections, object reflections (such as trees), and color variation. In addition, a multi-sensor mud detector was developed that fuses cues from color stereo and polarization sensors. Under the long range terrain classification task, a classifier was implemented that uses unsupervised and self-supervised learning of traversability to extend the classification of terrain over which the vehicle drives to the far-field. Under the pedestrian detection task, stereo vision was used to identify regions-of-interest in an image, classify those regions based on shape, and track detected pedestrians in three-dimensional world coordinates. To improve the detectability of partially occluded

  20. Stereo visualization in the ground segment tasks of the science space missions

    Science.gov (United States)

    Korneva, Natalia; Nazarov, Vladimir; Mogilevsky, Mikhail; Nazirov, Ravil

    The ground segment is one of the key components of any science space mission. Its functionality substantially defines the scientific effectiveness of the experiment as a whole. And it should be noted that its outstanding feature (in contrast to the other information systems of the scientific space projects) is interaction between researcher and project information system in order to interpret data being obtained during experiments. Therefore the ability to visualize the data being processed is essential prerequisite for ground segment's software and the usage of modern technological solutions and approaches in this area will allow increasing science return in general and providing a framework for new experiments creation. Mostly for the visualization of data being processed 2D and 3D graphics are used that is caused by the traditional visualization tools capabilities. Besides that the stereo data visualization methods are used actively in solving some tasks. However their usage is usually limited to such tasks as visualization of virtual and augmented reality, remote sensing data processing and suchlike. Low prevalence of stereo visualization methods in solving science ground segment tasks is primarily explained by extremely high cost of the necessary hardware. But recently appeared low cost hardware solutions for stereo visualization based on the page-flip method of views separation. In this case it seems promising to use the stereo visualization as an instrument for investigation of a wide range of problems, mainly for stereo visualization of complex physical processes as well as mathematical abstractions and models. The article is concerned with an attempt to use this approach. It describes the details and problems of using stereo visualization (page-flip method based on NVIDIA 3D Vision Kit, graphic processor GeForce) for display of some datasets of magnetospheric satellite onboard measurements and also in development of the software for manual stereo matching.

  1. Electron confinement in thin metal films. Structure, morphology and interactions

    Energy Technology Data Exchange (ETDEWEB)

    Dil, J.H.

    2006-05-15

    This thesis investigates the interplay between reduced dimensionality, electronic structure, and interface effects in ultrathin metal layers (Pb, In, Al) on a variety of substrates (Si, Cu, graphite). These layers can be grown with such a perfection that electron confinement in the direction normal to the film leads to the occurrence of quantum well states in their valence bands. These quantum well states are studied in detail, and their behaviour with film thickness, on different substrates, and other parameters of growth are used here to characterise a variety of physical properties of such nanoscale systems. The sections of the thesis deal with a determination of quantum well state energies for a large data set on different systems, the interplay between film morphology and electronic structure, and the influence of substrate electronic structure on their band shape; finally, new ground is broken by demonstrating electron localization and correlation effects, and the possibility to measure the influence of electron-phonon coupling in bulk bands. (orig.)

  2. One-electron versus electron-electron interaction contributions to the spin-spin coupling mechanism in nuclear magnetic resonance spectroscopy: analysis of basic electronic effects.

    Science.gov (United States)

    Gräfenstein, Jürgen; Cremer, Dieter

    2004-12-22

    For the first time, the nuclear magnetic resonance (NMR) spin-spin coupling mechanism is decomposed into one-electron and electron-electron interaction contributions to demonstrate that spin-information transport between different orbitals is not exclusively an electron-exchange phenomenon. This is done using coupled perturbed density-functional theory in conjunction with the recently developed J-OC-PSP [=J-OC-OC-PSP: Decomposition of J into orbital contributions using orbital currents and partial spin polarization)] method. One-orbital contributions comprise Ramsey response and self-exchange effects and the two-orbital contributions describe first-order delocalization and steric exchange. The two-orbital effects can be characterized as external orbital, echo, and spin transport contributions. A relationship of these electronic effects to zeroth-order orbital theory is demonstrated and their sign and magnitude predicted using simple models and graphical representations of first order orbitals. In the case of methane the two NMR spin-spin coupling constants result from totally different Fermi contact coupling mechanisms. (1)J(C,H) is the result of the Ramsey response and the self-exchange of the bond orbital diminished by external first-order delocalization external one-orbital effects whereas (2)J(H,H) spin-spin coupling is almost exclusively mitigated by a two-orbital steric exchange effect. From this analysis, a series of prediction can be made how geometrical deformations, electron lone pairs, and substituent effects lead to a change in the values of (1)J(C,H) and (2)J(H,H), respectively, for hydrocarbons.

  3. STEREO/SEPT observations of upstream particle events: almost monoenergetic ion beams

    Directory of Open Access Journals (Sweden)

    A. Klassen

    2009-05-01

    Full Text Available We present observations of Almost Monoenergetic Ion (AMI events in the energy range of 100–1200 keV detected with the Solar Electron and Proton Telescope (SEPT onboard both STEREO spacecraft. The energy spectrum of AMI events contain 1, 2, or 3 narrow peaks with the relative width at half maximum of 0.1–0.7 and their energy maxima varies for different events from 120 to 1200 keV. These events were detected close to the bow-shock (STEREO-A&B and to the magnetopause at STEREO-B as well as unexpectedly far upstream of the bow-shock and far away from the magnetotail at distances up to 1100 RE (STEREO-B and 1900 RE (STEREO-A. We discuss the origin of AMI events, the connection to the Earth's bow-shock and to the magnetosphere, and the conditions of the interplanetary medium and magnetosphere under which these AMI bursts occur. Evidence that the detected spectral peaks were caused by quasi-monoenergetic beams of protons, helium, and heavier ions are given. Furthermore, we present the spatial distribution of all AMI events from December 2006 until August 2007.

  4. Plasmonics—the interaction of light with metal surface electrons

    Science.gov (United States)

    Kroó, Norbert; Rácz, Péter

    2016-08-01

    The realization of light amplification by stimulated emission of radiation opened up an enormous wealth of potential new research and technologies in a broad wavelength range of electromagnetic waves. One of the new fields is plasmonics, based on the special properties of some materials with negative refractive index. In this case surface electromagnetic waves, coupled to surface electrons, the so-called surface plasmons can be generated. These waves among others represent a large enhancement of the EM field near the surface of the materials. The present paper illustrates some of the consequences of this phenomenon for a broad range of phenomena from ‘lasing’ to electron pairing. The latter is the basic condition for superconductivity, in our case found at room temperature. Measurements with a scanning tunneling microscope, furthermore electron and photon emission studies are the source of the presented experimental data.

  5. Interaction between SWCNTS and the mitochondriai electron transport chain

    Institute of Scientific and Technical Information of China (English)

    YanleiLiu; Yingge Zhang

    2012-01-01

    Objective: To investigate the effect of single-wall carbon nanotubes on the mitochondrial electron transport chain (METC) of tumor cells. Methods: Human hepatocarcinoma cell line HepG2 were cultured in DMEM medium (Hyclone) supplemented with 10% fetal calf serum (Gibco) in a atmosphere of 95% oxygen and 5% carbon dioxide under 37C. Cells were exposed by adding SWCNTs in the medium in concentrations of 1.5 - 12btg/ml. HepG2 cells exposed to narmal saline were used as control. The cells were collected after at 24h. The mitochondrial of HepG2 cells were obtained by density gradient centrifugation and were examined under transmis- sion electron microscope (TEM) . Four enzyme activity of the mitochondrial electron transport chain (METC) were determined by enzyme mark instrument. Results:

  6. Cavity-photon contribution to the effective interaction of electrons in parallel quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Gudmundsson, Vidar [Science Institute, University of Iceland, Reykjavik (Iceland); Sitek, Anna [Science Institute, University of Iceland, Reykjavik (Iceland); Department of Theoretical Physics, Faculty of Fundamental Problems of Technology, Wroclaw University of Technology (Poland); Abdullah, Nzar Rauf [Science Institute, University of Iceland, Reykjavik (Iceland); Physics Department, Faculty of Science and Science Education, School of Science, University of Sulaimani, Kurdistan Region (Iraq); Tang, Chi-Shung [Department of Mechanical Engineering, National United University, Miaoli (China); Manolescu, Andrei [School of Science and Engineering, Reykjavik University (Iceland)

    2016-05-15

    A single cavity photon mode is expected to modify the Coulomb interaction of an electron system in the cavity. Here we investigate this phenomena in a parallel double quantum dot system. We explore properties of the closed system and the system after it has been opened up for electron transport. We show how results for both cases support the idea that the effective electron-electron interaction becomes more repulsive in the presence of a cavity photon field. This can be understood in terms of the cavity photons dressing the polarization terms in the effective mutual electron interaction leading to nontrivial delocalization or polarization of the charge in the double parallel dot potential. In addition, we find that the effective repulsion of the electrons can be reduced by quadrupolar collective oscillations excited by an external classical dipole electric field. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Electromagnetic cascade in high energy electron, positron, and photon interactions with intense laser pulses

    CERN Document Server

    Bulanov, S S; Esarey, E; Leemans, W P

    2013-01-01

    The interaction of high energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when 3D effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and...

  8. Vector lifting schemes for stereo image coding.

    Science.gov (United States)

    Kaaniche, Mounir; Benazza-Benyahia, Amel; Pesquet-Popescu, Béatrice; Pesquet, Jean-Christophe

    2009-11-01

    Many research efforts have been devoted to the improvement of stereo image coding techniques for storage or transmission. In this paper, we are mainly interested in lossy-to-lossless coding schemes for stereo images allowing progressive reconstruction. The most commonly used approaches for stereo compression are based on disparity compensation techniques. The basic principle involved in this technique first consists of estimating the disparity map. Then, one image is considered as a reference and the other is predicted in order to generate a residual image. In this paper, we propose a novel approach, based on vector lifting schemes (VLS), which offers the advantage of generating two compact multiresolution representations of the left and the right views. We present two versions of this new scheme. A theoretical analysis of the performance of the considered VLS is also conducted. Experimental results indicate a significant improvement using the proposed structures compared with conventional methods.

  9. Molecular Understanding of Fullerene - Electron Donor Interactions in Organic Solar Cells

    KAUST Repository

    Ryno, Sean M.

    2016-09-13

    Organic solar cells hold promise of providing low-cost, renewable power generation, with current devices providing up to 13% power conversion efficiency. The rational design of more performant systems requires an in-depth understanding of the interactions between the electron donating and electron accepting materials within the active layers of these devices. Here, we explore works that give insight into the intermolecular interactions between electron donors and electron acceptors, and the impact of molecular orientations and environment on these interactions. We highlight, from a theoretical standpoint, the effects of intermolecular interactions on the stability of charge carriers at the donor/acceptor interface and in the bulk and how these interactions influence the nature of the charge transfer states as wells as the charge separation and charge transport processes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Strong electronic interaction and multiple quantum Hall ferromagnetic phases in trilayer graphene

    Science.gov (United States)

    Datta, Biswajit; Dey, Santanu; Samanta, Abhisek; Agarwal, Hitesh; Borah, Abhinandan; Watanabe, Kenji; Taniguchi, Takashi; Sensarma, Rajdeep; Deshmukh, Mandar M.

    2017-02-01

    Quantum Hall effect provides a simple way to study the competition between single particle physics and electronic interaction. However, electronic interaction becomes important only in very clean graphene samples and so far the trilayer graphene experiments are understood within non-interacting electron picture. Here, we report evidence of strong electronic interactions and quantum Hall ferromagnetism seen in Bernal-stacked trilayer graphene. Due to high mobility ~500,000 cm2 V-1 s-1 in our device compared to previous studies, we find all symmetry broken states and that Landau-level gaps are enhanced by interactions; an aspect explained by our self-consistent Hartree-Fock calculations. Moreover, we observe hysteresis as a function of filling factor and spikes in the longitudinal resistance which, together, signal the formation of quantum Hall ferromagnetic states at low magnetic field.

  11. Age is highly associated with stereo blindness among surgeons

    DEFF Research Database (Denmark)

    Fergo, Charlotte; Burcharth, Jakob; Pommergaard, Hans-Christian

    2016-01-01

    BACKGROUND: The prevalence of stereo blindness in the general population varies greatly within a range of 1-30 %. Stereo vision adds an extra dimension to aid depth perception and gives a binocular advantage in task completion. Lack of depth perception may lower surgical performance, potentially...... affecting surgical outcome. 3D laparoscopy offers stereoscopic vision of the operative field to improve depth perception and is being introduced to several surgical specialties; however, a normal stereo vision is a prerequisite. The aim of this study was to establish the prevalence of stereo blindness among...... and stereo tested by the use of the Random Dot E stereo test. Upon stereo testing, a demographic questionnaire was completed. Multivariate logistic regression analysis was employed to assess the association between stereo blindness and the variables resulting from the univariate analysis. RESULTS: Three...

  12. Interaction of slow electrons with high-pressure gases (quasi-liquids): Synthesis of our knowledge on slow electron-molecule interactions

    Science.gov (United States)

    McCorkle, D. L.; Christophorou, L. G.

    A crucial step in developing not only a coherent picture of radiation interaction with matter, but also to understand radiation effects and mechanisms, as well as the effects of chemical pollutants and toxic compounds, is to relate the often abundant knowledge on isolated molecules (low pressure gases) to that on liquids or solids. High pressure (40 to approx. 8000 kPa) electron swarm experiments are currently in operation yielding information as to the effects of the density and nature of the environment on fundamental electron-molecule interaction processes at densities intermediate to those corresponding to low pressure gases and liquids, and the gradual transition from isolated molecule to condensed phase behavior.

  13. Detection of moving objects using motion- and stereo-tuned operators.

    Science.gov (United States)

    Royden, Constance S; Sannicandro, Sean E; Webber, Laura M

    2015-01-01

    A person moving through the world must be able to identify moving objects in order to interact with them and successfully navigate. While image motion alone is sufficient to identify moving objects under many conditions, there may be some ambiguity as to whether an object is stationary or moving, depending on the object's angle of motion and distance from the observer. Adding a measure of depth from stereo cues can eliminate this ambiguity. Here we show that a model using operators tuned to image motion and stereo disparity can accurately locate moving objects and distinguish between stationary and moving objects in a scene through which an observer is moving.

  14. Many Body Diffusion and Interacting Electrons in a Harmonic Confinement

    Science.gov (United States)

    Luczak, F.; Brosens, F.; Devreese, J. T.; Lemmens, L. F.

    2001-06-01

    We present numerically exact energy estimates for two-dimensional electrons in a parabolic confinement. By application of an extension of the recently introduced many-body diffusion algorithm, the ground-state energies are simulated very efficiently. The new algorithm relies on partial antisymmetrization under permutation of particle coordinates. A comparison is made with earlier theoretical results for that system.

  15. Low energy electron interactions with complex biological targets

    Science.gov (United States)

    Orlando, Thomas

    2012-10-01

    The low energy (1-25 eV) electron-induced damage of DNA oligomers have been examined both theoretically and experimentally. Specifically, elastic scattering of 5-30 eV electrons within B-DNA 5'-CCGGCGCCGG-3' and A-DNA 5'-CGCGAATTCGCG-3' sequences has been calculated using the separable representation of a free-space electron propagator and a curved wave multiple scattering formalism. The disorder brought about by the surrounding water and helical base stacking leads to featureless amplitude build-up of elastically scattered electrons on the sugars and phosphate groups for all energies between 5-30 eV. However, some constructive interference features arising from diffraction were revealed when examining the structural waters within the major groove. We correlated these scattering features with measured DNA single and double strand breaks. Compound resonance states involving interfacial water and excitation energies > 5 eV seem to be required for lethal double strand breaks. We have recently extended this work to excitation energies below 5 eV by examining the damage using Raman-microscopy and scanning electrostatic force microscopy. Very efficient damage via single strand breaks is observed below 5 eV excitation energies. This involves π* negative ion resonances that are initially localized on the bases but transferred to the σ* states of the sugar-phosphate bond. The efficacies of these channels depend upon the base-pair sequences as well as the presence of water.

  16. Mechanisms of Interactions of Energetic Electrons with Epoxy Resins

    Science.gov (United States)

    Gupta, A.; Coulter, D. R.; Tsay, F. D.; Moacanin, J.

    1982-01-01

    The mechanism of deactivation of energy of excitation in a resin system was investigated on optical excitation as well as excitation by high energy electrons. This mechanism involves formation of excited state complexes, known as exciplexes which have a considerable charge transfer character. This mechanism will be used to develop a degradation model for epoxy matrix materials deployed in a space environment.

  17. Increasing Interactivity in Lectures Using an Electronic Voting System

    Science.gov (United States)

    Draper, S. W.; Brown, M. I.

    2004-01-01

    An overview of the experience of the opening two years of an institution-wide project in introducing electronic voting equipment for lectures is presented. Eight different departments and a wide range of group size (up to 300) saw some use. An important aspect of this is the organizational one of addressing the whole institution, rather than a…

  18. Ion and Electron Interactions at Thermal and Suprathermal Energies

    Science.gov (United States)

    1989-09-30

    halide ions with both esters occur so rapidly indicates that they are exothermic. If a thermody- namic cycle is constructed the enthalpy change, .H, for...efficiently neutralised to give products. Any OH X2H(v"-O) resulting from the dissociative recombination reactions of H30+, HCO 2+ and N20H+ with electrons

  19. Interplay between electron-phonon interaction and Hubbard repulsion: Bipolaron formation

    Energy Technology Data Exchange (ETDEWEB)

    Nath, S.; Mondal, N. S.; Ghosh, N. K., E-mail: nanda.ku@rediffmail.com [Department of Physics, University of Kalyani, Kalyani-741235, West Bengal (India)

    2015-06-24

    In the weak coupling limit, the 2D Hubbard model extended by on-site (local) and inter-site (long range) electron-phonon (EP) interaction has been investigated within Lanczos method of exact diagonalization (ED). On-site (S0) bipolaron formation has been favored by on-site EP interaction induced effective attraction between electrons. But, inter-site phonon mediated interaction between electrons helps to form both S0 and neighboring site (S1) bipolaron. It is further observed that both types of bipolaron formation are suppressed by on-site Hubbard repulsion.

  20. Electronic dynamics under effect of a nonlinear Morse interaction and a static electric field

    Science.gov (United States)

    Ranciaro Neto, A.; de Moura, F. A. B. F.

    2016-11-01

    Considering non-interacting electrons in a one-dimension alloy in which atoms are coupled by a Morse potential, we study the system dynamics in the presence of a static electric field. Calculations are performed assuming a quantum mechanical treatment for the electronic transport and a classical Hamiltonian model for the lattice vibrations. We report numerical evidence of the existence of a soliton-electron pair, even when the electric field is turned on, and we offer a description of how the existence of such a phase depends on the magnitude of the electric field and the electron-phonon interaction.

  1. What did we Learn About CMEs From the ISEE-3 Mission (of Relevance to the Stereo Mission)

    Science.gov (United States)

    Sanderson, T. R.

    2004-12-01

    ISEE-3 was launched in 1978 into a halo orbit around the L1 point. It was subsequently renamed ICE and sent on a journey around the Sun ahead of the earth in an orbit similar to that which one of the Stereo spacecraft will follow. ISEE-3 contained a comprehensive particles and fields instrumentation package, in many ways resembling the particles and fields packages of the Stereo mission. In this paper we discuss some results from the particle experiments which may have relevance to the upcoming Stereo mission. We will show observations of such aspects as particle time-intensity profiles, spectra, and anisotropies. We will discuss the relation with shock characteristics and also wave-particle interactions for the different type of particle events observed. We discuss the implications for the forthcoming Stereo mission.

  2. One- and many-electron self-interaction error in local and global hybrid functionals

    Science.gov (United States)

    Schmidt, Tobias; Kümmel, Stephan

    2016-04-01

    Electronic self-interaction poses a fundamental challenge in density-functional theory. It greatly limits, e.g., the physical interpretation of eigenvalues as electron removal energies. We here investigate whether local hybrid functionals that are designed to be free from one-electron self-interaction lead to occupied Kohn-Sham eigenvalues and orbitals that approximate photoemission observables well. We compare the local hybrid results to the ones from global hybrid functionals that only partially counteract the self-interaction, and to the results that are obtained with a Perdew-Zunger-type self-interaction correction. Furthermore, we check whether being nominally free from one-electron self-interaction translates into a reduced many-electron self-interaction error. Our findings show that this is not the case for the local hybrid functionals that we studied: In practice they are similar to global hybrids in many respects, despite being formally superior. This finding indicates that there is a conceptual difference between the Perdew-Zunger way and the local hybrid way of translating the one-electron condition to a many-electron system. We also point out and solve some difficulties that occur when using local hybrid functionals in combination with pseudopotentials.

  3. Probing Nanoscale Electronic and Magnetic Interaction with Scanning Tunneling Spectroscopy

    DEFF Research Database (Denmark)

    Bork, Jakob

    coverage the silver preferably nucleates on top of the bilayer high cobalt islands compared to directly on the Cu(111) substrate. Furthermore, the silver forms a combination of a reconstruction and a Moire pattern which is investigated with low-energy electron diraction and spectroscopic STM mapping at 6....... The heterostructure is found to have very interesting electronic properties. The d-related state from the now buried cobalt island is visible through the silver capping layer, but the silver Moire pattern modulates the spin-polarized cobalt d-related state in amplitude, energy position and width. This is related......, but the Fano line ii shape changes continuously from a dip to a peak. In the antiferromagnetic regime, inelastic spin-ip excitations reveal a splitting with a continuous increase in energy levels when pushing the atoms further together. This is supported by numerical renormalization group calculations...

  4. Inelastic processes of electron interactions with halouracils - cancer therapy agents

    Science.gov (United States)

    Limbachiya, Chetan; Vinodkumar, Minaxi; Swadia, Mohit

    2014-10-01

    We report electron impact total inelastic cross sections for important cancer treatment agents, 5-fluorouracil (5FU), 5-chlorouracil (5ClU) and 5-bromouracil (5BrU) from ionization threshold through 5000 eV. We have employed Spherical Complex Optical Potential [1,2] method to compute total inelastic cross sections Qinel and Complex Scattering Potential - ionization contribution (CSP-ic) formalism, to calculate total ionization cross sections Qion. Electron driven ionization cross sections for these important compounds of therapeutic interest are reported for the first time in this work. In absence of any ionization study for these cancer therapy agents, we have compared the data with their parent molecule Uracil. Present cross sections may serve as a reference estimates for experimental work.

  5. The envelope Hamiltonian for electron interaction with ultrashort pulses

    CERN Document Server

    Toyota, Koudai; Rost, Jan M

    2014-01-01

    For ultrashort VUV pulses with a pulse length comparable to the orbital time of the bound electrons they couple to we propose a simplified envelope Hamiltonian. It is based on the Kramers-Henneberger representation in connection with a Floquet expansion of the strong-field dynamics but keeps the time dependence of the pulse envelope explicit. Thereby, the envelope Hamiltonian captures the essence of the physics, -- light-induced shifts of bound states, single-photon absorption, and non-adiabatic electronic transitions. It delivers quantitatively accurate ionization dynamics and allows for physical insight into the processes occurring. Its minimal requirements for construction in terms of laser parameters make it ideally suited for a large class of atomic and molecular problems.

  6. Experiments on the Nuclear Interactions of Pions and Electrons

    Energy Technology Data Exchange (ETDEWEB)

    Ralph C. Minehart

    2005-04-15

    This is the final technical report. Yearly Progress Reports were submitted throughout the duration of the project. Along with our publications, these reports provide a detailed record of our accomplishments. This report largely consists of a summary of the technical activities carried out during last 2-1/2 years of the project, along with a list of papers published in the period from 2002-2005. Our work during this period involved the following: 1. Electro-production of excited states of the nucleon through the analysis of exclusive single pion production reactions induced by polarized electrons incident on both polarized and unpolarized nucleon targets. (JLab) 2. Measurement of proton and deuteron spin structure functions in and above the nucleon resonance region at low and moderate $Q^2$, using inclusive electron-proton and electron deuteron scattering (JLAB). 3. Contributions to the PRIMEX experiment (JLab). 4. A precise measurement of the branching ratio for pion beta decay was carried out along with other members of the PIBETA collaboration (PSI). The first three, labeled JLab, were experiments made with the CLAS detector at the Thomas Jefferson Laboratory in Newport News, VA. The PIBETA experiment was carried out using a low energy pion beam at the Paul Scherrer Institute in Villigen, Switzerland.

  7. Evolution of Spin and Charge in a System with Interacting Impurity and Conducting Electrons

    Institute of Scientific and Technical Information of China (English)

    张永梅; 熊诗杰

    2003-01-01

    We investigate the dynamics of spin and charge in an interacting system consisting of impurity and conducting electrons.The time evolution of spin and charge in the impurity is given by solving the time-dependent Schrodinger equations for the many-body states of the interacting system.By switching on the interaction between impurity and conducting electrons,the spin and charge of the impurity begin oscillations with frequencies that reflect the elementary excitations of the interacting system.The dynamics reflects the basic picture of the Kondo effect.

  8. Exact and LDA entanglement of tailored densities in an interacting one-dimensional electron system

    Energy Technology Data Exchange (ETDEWEB)

    Coe, J P; D' Amico, I, E-mail: jpc503@york.ac.u, E-mail: ida500@york.ac.u [Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2010-01-01

    We calculate the 'exact' potential corresponding to a one-dimensional interacting system of two electrons with a specific, tailored density. We use one-dimensional density-functional theory with a local-density approximation (LDA) on the same system and calculate densities and energies, which are compared with the 'exact' ones. The 'interacting-LDA system'[4] corresponding to the LDA density is then found and its potential compared with the original one. Finally we calculate and compare the spatial entanglement of the electronic systems corresponding to the interacting-LDA and original interacting system.

  9. Modified Monte Carlo method for study of electron transport in degenerate electron gas in the presence of electron–electron interactions, application to graphene

    Energy Technology Data Exchange (ETDEWEB)

    Borowik, Piotr, E-mail: pborow@poczta.onet.pl [Warsaw University of Technology, Faculty of Physics, ul. Koszykowa 75, 00-662 Warszawa (Poland); Thobel, Jean-Luc, E-mail: jean-luc.thobel@iemn.univ-lille1.fr [Institut d' Electronique, de Microélectronique et de Nanotechnologies, UMR CNRS 8520, Université Lille 1, Avenue Poincaré, CS 60069, 59652 Villeneuve d' Ascq Cédex (France); Adamowicz, Leszek, E-mail: adamo@if.pw.edu.pl [Warsaw University of Technology, Faculty of Physics, ul. Koszykowa 75, 00-662 Warszawa (Poland)

    2017-07-15

    Standard computational methods used to take account of the Pauli Exclusion Principle into Monte Carlo (MC) simulations of electron transport in semiconductors may give unphysical results in low field regime, where obtained electron distribution function takes values exceeding unity. Modified algorithms were already proposed and allow to correctly account for electron scattering on phonons or impurities. Present paper extends this approach and proposes improved simulation scheme allowing including Pauli exclusion principle for electron–electron (e–e) scattering into MC simulations. Simulations with significantly reduced computational cost recreate correct values of the electron distribution function. Proposed algorithm is applied to study transport properties of degenerate electrons in graphene with e–e interactions. This required adapting the treatment of e–e scattering in the case of linear band dispersion relation. Hence, this part of the simulation algorithm is described in details.

  10. Correlation effects on the energy spectra of quantum dot electrons with harmonic model interactions

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The low-lying excitation energy spectra of two, three and five quantum dot electrons with harmonic model interactions in a large magnetic field are calculated by the Hartree-Fock(HF) methods. Correlation effects on the energy level structures are investigated by comparing the HF results with the exact ones. It is found that the pure collective excitations(center-of-mass mode quanta) existing in the exact energy spectra do not appear in the HF energy spectra. The degeneracies of energy levels are also related to the correlation interactions, especially in the energy spectrum of two electrons. In the cases of more than two electrons, as the electron-electron interaction strength is increased the HF energy levels exhibit more complex crossings than the exact ones.

  11. Electron-electron interactions in the chemical bond: ``1/3” Effect in the bond length of hydrogen molecule

    Indian Academy of Sciences (India)

    P Ganguly

    2001-10-01

    The prominent ``1/3” effect observed in the Hall effect plateaus of twodimensional electron gas (2DEG) systems has been postulated to indicating 1/3 fractional charge quasiparticle excitations arising from electron-electron interactions. Tunneling shot-noise experiments on 2DEF exhibiting fractional quantum Hall effect (FQHE) shows evidence for tunnelling of particles with and /3 charges for a constant band mass. A ``1/3” effect in the hydrogen molecule is seen in as much as its internuclear distance, - = - + +, with |+/-| = 1/3. This is examined in terms of electron-electron interactions involving electron- and hole quasiparticles, (-) and (ℎ+), equivalent to those observed in FQHE shot-noise experiments. The (/) ratio of the (-) and (ℎ+) quasiparticles is kept at 1: -3. Instead of a 2DEG, these particles are treated as being in flat Bohr orbits. A treatment in the language of charge-flux tube composites for the hydrogen atom as well as the hydrogen molecule is attempted. Such treatment gives important insights into changes in chemical potential and bond energy on crossing a phase boundary during the atom-bond transition as well as on models for FQHE itself.

  12. Pairing and unpairing electron densities in organic systems: Two-electron three center through space and through bonds interactions

    Energy Technology Data Exchange (ETDEWEB)

    Lobayan, Rosana M., E-mail: rmlb@exa.unne.edu.ar [Departamento de Física, Facultad de Ciencias Exactas, Naturales y Agrimensura, Universidad Nacional del Nordeste, 3400, Corrientes (Argentina); Bochicchio, Roberto C., E-mail: rboc@df.uba.ar [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, and IFIBA, CONICET, Ciudad Universitaria, 1428, Buenos Aires (Argentina)

    2014-05-07

    Two-electron three-center bonding interactions in organic ions like methonium (CH{sub 5}{sup +}), ethonium (C{sub 2}H{sub 7}{sup +}), and protonated alkanes n−C{sub 4}H{sub 11}{sup +} isomers (butonium cations) are described and characterized within the theoretical framework of the topological analysis of the electron density decomposition into its effectively paired and unpaired contributions. These interactions manifest in some of this type of systems as a concentration of unpaired electron cloud around the bond paths, in contrast to the well known paradigmatic boron hydrids in which it is not only concentrated close to the atomic nucleus and the bond paths but out of them and over the region defined by the involved atoms as a whole. This result permits to propose an attempt of classification for these interactions based in such manifestations. In the first type, it is called as interactions through bonds and in the second type as interactions through space type.

  13. Stereoselectivity in metallocene-catalyzed coordination polymerization of renewable methylene butyrolactones: From stereo-random to stereo-perfect polymers

    KAUST Repository

    Chen, Xia

    2012-05-02

    Coordination polymerization of renewable α-methylene-γ-(methyl) butyrolactones by chiral C 2-symmetric zirconocene catalysts produces stereo-random, highly stereo-regular, or perfectly stereo-regular polymers, depending on the monomer and catalyst structures. Computational studies yield a fundamental understanding of the stereocontrol mechanism governing these new polymerization reactions mediated by chiral metallocenium catalysts. © 2012 American Chemical Society.

  14. Controlling the electronic structure of nanocrystal assemblies by variation of the particle - particle interaction

    Energy Technology Data Exchange (ETDEWEB)

    Bostedt, C; van Buuren, T; Willey, T M; Terminello, L J

    2004-09-27

    The change in the electronic structure of germanium nanocrystals is investigated as their concentration is increased from non-interacting, individual particles to assembled arrays of particles. The electronic structure of the individual nanoclusters shows clear effects due to quantum confinement which are lost in the concentrated assemblies of bare particles. When the surface of the individual particles is passivated, they retain their quantum confinement properties also upon assembly. These effects are interpreted in terms of a particle - particle interaction model.

  15. Specular Reflectivity and Hot-Electron Generation in High-Contrast Relativistic Laser-Plasma Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Gregory Elijah [The Ohio State Univ., Columbus, OH (United States)

    2013-01-01

    Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the cost of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic

  16. Polyyne electronic and vibrational properties under environmental interactions

    Science.gov (United States)

    Wanko, Marius; Cahangirov, Seymur; Shi, Lei; Rohringer, Philip; Lapin, Zachary J.; Novotny, Lukas; Ayala, Paola; Pichler, Thomas; Rubio, Angel

    2016-11-01

    Recently the novel system of linear carbon chains inside double-walled carbon nanotubes has extended the length of s p1 hybridized carbon chains from 44 to thousands of atoms [Shi et al., Nat. Mater. 15, 634 (2016), 10.1038/nmat4617]. The optoelectronic properties of these ultralong chains are poorly described by current theoretical models, which are based on short chain experimental data and assume a constant environment. As such, a physical understanding of the system in terms of charge transfer and van der Waals interactions is widely missing. We provide a reference for the intrinsic Raman frequency of polyynes in vacuo and explicitly describe the interactions between polyynes and carbon nanotubes. We find that van der Waals interactions strongly shift this frequency, which has been neither expected nor described for other intramolecular C-C stretching vibrations. As a consequence of charge transfer from the tube to the chain, the Raman response of long chains is qualitatively different from the known phonon dispersion of polymers close to the Γ point. Based on these findings we show how to correctly interpret the Raman data, considering the nanotube's properties. This is essential for its use as an analytical tool to optimize the growth process for future applications.

  17. Head Pose Estimation from Passive Stereo Images

    DEFF Research Database (Denmark)

    Breitenstein, Michael D.; Jensen, Jeppe; Høilund, Carsten

    2009-01-01

    function. Our algorithm incorporates 2D and 3D cues to make the system robust to low-quality range images acquired by passive stereo systems. It handles large pose variations (of ±90 ° yaw and ±45 ° pitch rotation) and facial variations due to expressions or accessories. For a maximally allowed error of 30...

  18. Artistic Stereo Imaging by Edge Preserving Smoothing

    NARCIS (Netherlands)

    Papari, Giuseppe; Campisi, Patrizio; Callet, Patrick Le; Petkov, Nicolai

    2009-01-01

    Stereo imaging is an important area of image and video processing, with exploding progress in the last decades. An open issue in this field is the understanding of the conditions under which the straightforward application of a given image processing operator to both the left and right image of a st

  19. Hybrid-Based Dense Stereo Matching

    Science.gov (United States)

    Chuang, T. Y.; Ting, H. W.; Jaw, J. J.

    2016-06-01

    Stereo matching generating accurate and dense disparity maps is an indispensable technique for 3D exploitation of imagery in the fields of Computer vision and Photogrammetry. Although numerous solutions and advances have been proposed in the literature, occlusions, disparity discontinuities, sparse texture, image distortion, and illumination changes still lead to problematic issues and await better treatment. In this paper, a hybrid-based method based on semi-global matching is presented to tackle the challenges on dense stereo matching. To ease the sensitiveness of SGM cost aggregation towards penalty parameters, a formal way to provide proper penalty estimates is proposed. To this end, the study manipulates a shape-adaptive cross-based matching with an edge constraint to generate an initial disparity map for penalty estimation. Image edges, indicating the potential locations of occlusions as well as disparity discontinuities, are approved by the edge drawing algorithm to ensure the local support regions not to cover significant disparity changes. Besides, an additional penalty parameter 𝑃𝑒 is imposed onto the energy function of SGM cost aggregation to specifically handle edge pixels. Furthermore, the final disparities of edge pixels are found by weighting both values derived from the SGM cost aggregation and the U-SURF matching, providing more reliable estimates at disparity discontinuity areas. Evaluations on Middlebury stereo benchmarks demonstrate satisfactory performance and reveal the potency of the hybrid-based dense stereo matching method.

  20. The potential risk of personal stereo players

    DEFF Research Database (Denmark)

    Hammershøi, Dorte; Ordoñez, Rodrigo Pizarro; Reuter, Karen

    2010-01-01

    The technological development within personal stereo systems, such as MP3 players, e. g. iPods, has changed music listening habits from home entertainment to everyday and everywhere use. The technology has developed considerably, since the introduction of cassette players and CD walkmen. High...

  1. The potential risk of personal stereo players

    DEFF Research Database (Denmark)

    Hammershøi, Dorte; Ordoñez, Rodrigo Pizarro; Reuter, Karen

    2010-01-01

    The technological development within personal stereo systems,such as MP3 players, e. g. iPods, has changed music listening habits from home entertainment to everyday and everywhere use. The technology has developed considerably, since the introduction of cassette players and CD walkmen. High...

  2. Artistic Stereo Imaging by Edge Preserving Smoothing

    NARCIS (Netherlands)

    Papari, Giuseppe; Campisi, Patrizio; Callet, Patrick Le; Petkov, Nicolai

    2009-01-01

    Stereo imaging is an important area of image and video processing, with exploding progress in the last decades. An open issue in this field is the understanding of the conditions under which the straightforward application of a given image processing operator to both the left and right image of a

  3. Accuracy and robustness evaluation in stereo matching

    Science.gov (United States)

    Nguyen, Duc M.; Hanca, Jan; Lu, Shao-Ping; Schelkens, Peter; Munteanu, Adrian

    2016-09-01

    Stereo matching has received a lot of attention from the computer vision community, thanks to its wide range of applications. Despite of the large variety of algorithms that have been proposed so far, it is not trivial to select suitable algorithms for the construction of practical systems. One of the main problems is that many algorithms lack sufficient robustness when employed in various operational conditions. This problem is due to the fact that most of the proposed methods in the literature are usually tested and tuned to perform well on one specific dataset. To alleviate this problem, an extensive evaluation in terms of accuracy and robustness of state-of-the-art stereo matching algorithms is presented. Three datasets (Middlebury, KITTI, and MPEG FTV) representing different operational conditions are employed. Based on the analysis, improvements over existing algorithms have been proposed. The experimental results show that our improved versions of cross-based and cost volume filtering algorithms outperform the original versions with large margins on Middlebury and KITTI datasets. In addition, the latter of the two proposed algorithms ranks itself among the best local stereo matching approaches on the KITTI benchmark. Under evaluations using specific settings for depth-image-based-rendering applications, our improved belief propagation algorithm is less complex than MPEG's FTV depth estimation reference software (DERS), while yielding similar depth estimation performance. Finally, several conclusions on stereo matching algorithms are also presented.

  4. Scalar-pseudoscalar interactions in neutrino-electron scattering

    CERN Document Server

    Gaitán, R; Miranda, O G; de Oca, J H Montes

    2013-01-01

    Many extensions to the Standard Model imply the existence of new charged scalar Higgs bosons. We study the contribution of a general scalar or pseudoscalar coupling for the neutrino-electron scattering. We take a phenomenological approach in order to obtain model independent limits to the couplings that arise in this picture. We illustrate the reach of the constraints by studying the particular case of the type III two Higgs doublet model, where we have found new constraints to some elements of the Yukawa couplings mixing matrix ($|Y_{ee}| \\leq 1 \\times 10^{-1}$ and $|Y_{e\\mu}| \\leq 7\\times10^{-2}$ at 90% CL).

  5. Unraveling the acoustic electron-phonon interaction in graphene

    DEFF Research Database (Denmark)

    Kaasbjerg, Kristen; Thygesen, Kristian S.; Jacobsen, Karsten W.

    2012-01-01

    Using a first-principles approach we calculate the electron-phonon couplings in graphene for the transverse and longitudinal acoustic phonons. Analytic forms of the coupling matrix elements valid in the long-wavelength limit are found to give an almost quantitative description of the first...... that the intrinsic effective acoustic deformation potential of graphene is Ξeff=6.8 eV and that the temperature dependence of the mobility μ~T-α in the Bloch-Gru¨neisen regime increases beyond an α=4 dependence even in the absence of screening when the true coupling matrix elements are considered. The α>4...

  6. Two Interacting Electrons in a Vertically Coupled Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang; WANG An-Mei

    2004-01-01

    We study a two-electron system in a double-layer quantum dot under a magnetic field by means of the exact diagonalization of the Hamiltonian matrix.We find that discontinuous ground-state energy transitions are induced by an external magnetic field in the case of strong coupling.However,in the case of weak coupling,the angular momentum L of the true ground state does not change in accordance with the change of the magnetic field B and remains L=0.

  7. Quantum-trajectory Monte Carlo method for study of electron-crystal interaction in STEM.

    Science.gov (United States)

    Ruan, Z; Zeng, R G; Ming, Y; Zhang, M; Da, B; Mao, S F; Ding, Z J

    2015-07-21

    In this paper, a novel quantum-trajectory Monte Carlo simulation method is developed to study electron beam interaction with a crystalline solid for application to electron microscopy and spectroscopy. The method combines the Bohmian quantum trajectory method, which treats electron elastic scattering and diffraction in a crystal, with a Monte Carlo sampling of electron inelastic scattering events along quantum trajectory paths. We study in this work the electron scattering and secondary electron generation process in crystals for a focused incident electron beam, leading to understanding of the imaging mechanism behind the atomic resolution secondary electron image that has been recently achieved in experiment with a scanning transmission electron microscope. According to this method, the Bohmian quantum trajectories have been calculated at first through a wave function obtained via a numerical solution of the time-dependent Schrödinger equation with a multislice method. The impact parameter-dependent inner-shell excitation cross section then enables the Monte Carlo sampling of ionization events produced by incident electron trajectories travelling along atom columns for excitation of high energy knock-on secondary electrons. Following cascade production, transportation and emission processes of true secondary electrons of very low energies are traced by a conventional Monte Carlo simulation method to present image signals. Comparison of the simulated image for a Si(110) crystal with the experimental image indicates that the dominant mechanism of atomic resolution of secondary electron image is the inner-shell ionization events generated by a high-energy electron beam.

  8. Robust surface reconstruction by design-guided SEM photometric stereo

    Science.gov (United States)

    Miyamoto, Atsushi; Matsuse, Hiroki; Koutaki, Gou

    2017-04-01

    We present a novel approach that addresses the blind reconstruction problem in scanning electron microscope (SEM) photometric stereo for complicated semiconductor patterns to be measured. In our previous work, we developed a bootstrapping de-shadowing and self-calibration (BDS) method, which automatically calibrates the parameter of the gradient measurement formulas and resolves shadowing errors for estimating an accurate three-dimensional (3D) shape and underlying shadowless images. Experimental results on 3D surface reconstruction demonstrated the significance of the BDS method for simple shapes, such as an isolated line pattern. However, we found that complicated shapes, such as line-and-space (L&S) and multilayered patterns, produce deformed and inaccurate measurement results. This problem is due to brightness fluctuations in the SEM images, which are mainly caused by the energy fluctuations of the primary electron beam, variations in the electronic expanse inside a specimen, and electrical charging of specimens. Despite these being essential difficulties encountered in SEM photometric stereo, it is difficult to model accurately all the complicated physical phenomena of electronic behavior. We improved the robustness of the surface reconstruction in order to deal with these practical difficulties with complicated shapes. Here, design data are useful clues as to the pattern layout and layer information of integrated semiconductors. We used the design data as a guide of the measured shape and incorporated a geometrical constraint term to evaluate the difference between the measured and designed shapes into the objective function of the BDS method. Because the true shape does not necessarily correspond to the designed one, we use an iterative scheme to develop proper guide patterns and a 3D surface that provides both a less distorted and more accurate 3D shape after convergence. Extensive experiments on real image data demonstrate the robustness and effectiveness

  9. Dynamics of electron currents in nanojunctions with time-varying components and interactions

    Science.gov (United States)

    Cuansing, Eduardo C.; Bayocboc, Francis A.; Laurio, Christian M.

    2017-08-01

    We study the dynamics of the electron current in nanodevices where there are time-varying components and interactions. These devices are a nanojunction attached to heat baths and with dynamical electron-phonon interactions, and a nanojunction with photon beams incident and reflected at the channel. We use the two-time nonequilibrium Green's functions technique to calculate the time-dependent electron current flowing across the devices. We find that whenever a sudden change occurs in the device, the current takes time to react to the abrupt change, overshoots, oscillates, and eventually settles down to a steady value. With dynamical electron-phonon interactions, the interaction gives rise to a net resistance that reduces the flow of current across the device when a source-drain bias potential is attached. In the presence of dynamical electron-photon interactions, the photons drive the electrons to flow. The direction of flow, however, depends on the frequencies of the incident photons. Furthermore, the direction of electron flow in one lead is exactly opposite to the direction of flow in the other lead thereby resulting in no net change in current flowing across the device.

  10. Signatures of Interchange Reconnection: STEREO, ACE and Hinode Observations Combined

    CERN Document Server

    Baker, D; Van Driel-Gesztelyi, L; Demoulin, P; Harra, L K; Lavraud, B; Davies, J A; Optiz, A; Luhmann, J G; Sauvaud, J A; Galvin, A B

    2009-01-01

    Combining STEREO, ACE and Hinode observations has presented an opportunity to follow a filament eruption and coronal mass ejection (CME) on the 17th of October 2007 from an active region (AR) inside a coronal hole (CH) into the heliosphere. This particular combination of `open' and closed magnetic topologies provides an ideal scenario for interchange reconnection to take place. With Hinode and STEREO data we were able to identify the emergence time and type of structure seen in the in-situ data four days later. On the 21st, ACE observed in-situ the passage of an ICME with `open' magnetic topology. The magnetic field configuration of the source, a mature AR located inside an equatorial CH, has important implications for the solar and interplanetary signatures of the eruption. We interpret the formation of an `anemone' structure of the erupting AR and the passage in-situ of the ICME being disconnected at one leg, as manifested by uni-directional suprathermal electron flux in the ICME, to be a direct result of i...

  11. The High Energy Telescopes for the STEREO Mission

    Science.gov (United States)

    von Rosenvinge, T.T.; Cummings, A.C.; Leske, R.A.; Mewaldt, R.A.; Reames, D.V.; Stone, E.C.; Wiedenbeck, M.E.

    We describe the High Energy Telescopes (HETs), which are part of the IMPACT investigation for the STEREO mission (Principal Investigator: Janet Luhmann, University of California at Berkeley). The two STEREO spacecraft were launched from Cape Canaveral, FL on October 25, 2006. High energy electrons (~ 0.7 -6 MeV) and nuclei from hydrogen to iron (~ 13 - 200 MeV/nucleon) are detected by the HETs, one on each spacecraft. Observations from one pass through the Earth’s magnetosphere and from four X-class solar events in December, 2006 are presented to illustrate the capabilities of the HETs. The HET observations are also compared with observations from other spacecraft. The event of December 13th was the first Ground Level Event in almost two years. We will compare the elemental composition of this event with that of the previous Ground Level Event on January 20, 2005. This work was supported by NASA (at Caltech and JPL under contract NAS5-00133 and grant NAG5-12929).

  12. Stereo-particle image velocimetry uncertainty quantification

    Science.gov (United States)

    Bhattacharya, Sayantan; Charonko, John J.; Vlachos, Pavlos P.

    2017-01-01

    Particle image velocimetry (PIV) measurements are subject to multiple elemental error sources and thus estimating overall measurement uncertainty is challenging. Recent advances have led to a posteriori uncertainty estimation methods for planar two-component PIV. However, no complete methodology exists for uncertainty quantification in stereo PIV. In the current work, a comprehensive framework is presented to quantify the uncertainty stemming from stereo registration error and combine it with the underlying planar velocity uncertainties. The disparity in particle locations of the dewarped images is used to estimate the positional uncertainty of the world coordinate system, which is then propagated to the uncertainty in the calibration mapping function coefficients. Next, the calibration uncertainty is combined with the planar uncertainty fields of the individual cameras through an uncertainty propagation equation and uncertainty estimates are obtained for all three velocity components. The methodology was tested with synthetic stereo PIV data for different light sheet thicknesses, with and without registration error, and also validated with an experimental vortex ring case from 2014 PIV challenge. Thorough sensitivity analysis was performed to assess the relative impact of the various parameters to the overall uncertainty. The results suggest that in absence of any disparity, the stereo PIV uncertainty prediction method is more sensitive to the planar uncertainty estimates than to the angle uncertainty, although the latter is not negligible for non-zero disparity. Overall the presented uncertainty quantification framework showed excellent agreement between the error and uncertainty RMS values for both the synthetic and the experimental data and demonstrated reliable uncertainty prediction coverage. This stereo PIV uncertainty quantification framework provides the first comprehensive treatment on the subject and potentially lays foundations applicable to volumetric

  13. Persistent currents for interacting electrons in ballistic/chaotic billiards

    Science.gov (United States)

    Zelyak, Oleksandr; Murthy, Ganpathy

    2005-03-01

    We study persistent currents in a quantum billiard enclosing a magnetic flux φ by analytical and numerical methods. We concentrate on the family of Robnik-Berry billiards generated by conformal maps of the unit disk. We study the persistent current as a function of magnetic flux and parameters of the billiard in the chaotic regime. We include Fermi-liquid interactions in a mean-field approach, justified by the recent large-N approach[1] for ballistic/chaotic quantum dots. [1] G. Murthy, R. Shankar, D. Herman, and H. Mathur, Phys. Rev. B 69, 075321 (2004); G. Murthy, R. Shankar, and H. Mathur, cond-mat/0411280.

  14. Interactive learning in medicine: socrates in electronic clothes.

    Science.gov (United States)

    Brezis, M; Cohen, R

    2004-01-01

    Traditional lectures have limited ability to maintain attention and to promote changes in behaviour. Active learning, which stimulates the audience to think and participate, may be more effective. We describe our experience with an interactive polling system in lectures to physicians and students. Audience's answers to questions are displayed, providing instant feedback to both lecturer and audience, and promoting the use of case discussions and problem-solving exercises. In our experience, this modality improves the quality of clinical learning and deserves further evaluation.

  15. Final Report on Investigation of the Electron Interactions in Graphene

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Philip [Columbia University

    2015-02-14

    In graphene, combined with the real spin degree of freedom, which exhibits SU(2) symmetry, the total internal degrees of freedom of graphene carriers is thus described by a larger SU(4) symmetry, which produces a richer space for potential phenomena of emergent correlated electron phenomena. The major part of this proposal is exploring this unique multicomponent correlated system in the quantum limit. In the current period of DOE BES support we have made several key advances that will serve as a foundation for the new studies in this proposal. Employing the high-mobility encapsulated graphene heterostructures developed during the current phase of research, we have investigated spin and valley quantum Hall ferromagnetism in graphene and discovered a spin phase transition leading to a quantum spin Hall analogue. We have also observed the fractal quantum Hall effect arising from the Hofstadter’s butterfly energy spectrum. In addition, we have discovered multiband transport phenomena in bilayer graphene at high carrier densities.

  16. Interactive Web-based tutorials for teaching digital electronics

    Science.gov (United States)

    Bailey, Donald G.

    2000-10-01

    With a wide range of student abilities in a class, it is difficult to effectively teach and stimulate all students. A series of web based tutorials was designed to help weaker students and stretch the stronger students. The tutorials consist of a series of HTML web pages with embedded Java applets. This combination is particularly powerful for providing interactive demonstrations because any textual content may be easily provided within the web page. The applet is able to be a compete working program that dynamically illustrates the concept, or provides a working environment for the student to experiment and work through their solution. The applet is dynamic, and responds to the student through both mouse clicks and keyboard entry. These allow the student to adjust parameters, make selections, and affect the way the program is run or information is displayed. Such interaction allows each applet to provide a mini demonstration or experiment to help the student understand a particular concept or technique. The approach taken is illustrated with a tutorial that dynamically shows the relationships between a truth table, Karnaugh amp, logic circuit and Boolean algebra representations of a logic function, and dramatically illustrates the effect of minimization on the resultant circuit. Use of the tutorial has resulted in significant benefits, particularly with weaker students.

  17. Mobility and bulk electron-phonon interaction in two-dimensional materials

    DEFF Research Database (Denmark)

    Gunst, Tue; Brandbyge, Mads; Markussen, Troels

    2015-01-01

    We present calculations of the phonon-limited mobility in intrinsic n-type monolayer graphene, silicene and MoS2. The material properties, including the electron-phonon interaction, are calculated from first principles. Unlike graphene, the carriers in silicene show strong interaction with the out...

  18. Extraordinary waves in two dimensional electron gas with separate spin evolution and Coulomb exchange interaction

    CERN Document Server

    Andreev, Pavel A

    2016-01-01

    Hydrodynamics analysis of waves in two-dimensional degenerate electron gas with the account of separate spin evolution is presented. The transverse electric field is included along with the longitudinal electric field. The Coulomb exchange interaction is included in the analysis. In contrast with the three-dimensional plasma-like mediums the contribution of the transverse electric field is small. We show the decrease of frequency of both the extraordinary (Langmuir) wave and the spin-electron acoustic wave due to the exchange interaction. Moreover, spin-electron acoustic wave has negative dispersion at the relatively large spin-polarization. Corresponding dispersion dependencies are presented and analyzed.

  19. Effect of connecting wires on the decoherence due to electron-electron interaction in a metallic ring

    Science.gov (United States)

    Texier, Christophe

    2007-10-01

    We consider the weak localization in a ring connected to reservoirs through leads of finite length and submitted to a magnetic field. The effect of decoherence due to electron-electron interaction on the harmonics of Al’tshuler-Aronov-Spivak [JETP Lett. 33, 94 (1981)] oscillations is studied, and more specifically the effect of the leads. Two results are obtained for short and long lead regimes. The scale at which the crossover occurs is discussed. The long lead regime is shown to be more realistic experimentally.

  20. Electromagnetic cascade in high-energy electron, positron, and photon interactions with intense laser pulses

    Science.gov (United States)

    Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2013-06-01

    The interaction of high-energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high-energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when three-dimensional effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and photons are calculated for the case of a high-energy e-beam interacting with a counterstreaming, short intense laser pulse. The energy loss of the e-beam, which requires a self-consistent quantum description, plays an important role in this process, as well as provides a clear experimental observable for the transition from the classical to quantum regime of interaction.

  1. Possible interaction between thermal electrons and vibrationally excited N2 in the lower E-region

    Directory of Open Access Journals (Sweden)

    C. Z. Cheng

    2011-03-01

    Full Text Available As one of the tasks to find the energy source(s of thermal electrons, which elevate(s electron temperature higher than neutral temperature in the lower ionosphere E-region, energy distribution function of thermal electron was measured with a sounding rocket at the heights of 93–131 km by the applying second harmonic method. The energy distribution function showed a clear hump at the energy of ~0.4 eV. In order to find the reason of the hump, we conducted laboratory experiment. We studied difference of the energy distribution functions of electrons in thermal energy range, which were measured with and without EUV radiation to plasma of N2/Ar and N2/O2 gas mixture respectively. For N2/Ar gas mixture plasma, the hump is not clearly identified in the energy distribution of thermal electrons. On the other hand for N2/O2 gas mixture, which contains vibrationally excited N2, a clear hump is found when irradiated by EUV. The laboratory experiment seems to suggest that the hump is produced as a result of interaction between vibrationally excited N2 and thermal electrons, and this interaction is the most probable heating source for the electrons of thermal energy range in the lower E-region. It is also suggested that energy distribution of the electrons in high energy part may not be Maxwellian, and DC probe measures the electrons which are non Maxwellian, and therefore "electron temperature" is calculated higher.

  2. Concepts relating magnetic interactions, intertwined electronic orders, and strongly correlated superconductivity.

    Science.gov (United States)

    Davis, J C Séamus; Lee, Dung-Hai

    2013-10-29

    Unconventional superconductivity (SC) is said to occur when Cooper pair formation is dominated by repulsive electron-electron interactions, so that the symmetry of the pair wave function is other than an isotropic s-wave. The strong, on-site, repulsive electron-electron interactions that are the proximate cause of such SC are more typically drivers of commensurate magnetism. Indeed, it is the suppression of commensurate antiferromagnetism (AF) that usually allows this type of unconventional superconductivity to emerge. Importantly, however, intervening between these AF and SC phases, intertwined electronic ordered phases (IP) of an unexpected nature are frequently discovered. For this reason, it has been extremely difficult to distinguish the microscopic essence of the correlated superconductivity from the often spectacular phenomenology of the IPs. Here we introduce a model conceptual framework within which to understand the relationship between AF electron-electron interactions, IPs, and correlated SC. We demonstrate its effectiveness in simultaneously explaining the consequences of AF interactions for the copper-based, iron-based, and heavy-fermion superconductors, as well as for their quite distinct IPs.

  3. Nonlinear thermoelectric transport in single-molecule junctions: the effect of electron-phonon interactions

    Science.gov (United States)

    Zimbovskaya, Natalya A.

    2016-07-01

    In this paper, we theoretically analyze steady-state thermoelectric transport through a single-molecule junction with a vibrating bridge. The thermally induced charge current in the system is explored using a nonequilibrium Green function formalism. We study the combined effects of Coulomb interactions between charge carriers on the bridge and electron-phonon interactions on the thermocurrent beyond the linear response regime. It is shown that electron-vibron interactions may significantly affect both the magnitude and the direction of the thermocurrent, and vibrational signatures may appear.

  4. Plasmons in doped finite carbon nanotubes and their interactions with fast electrons and quantum emitters

    Science.gov (United States)

    de Vega, Sandra; Cox, Joel D.; de Abajo, F. Javier García

    2016-08-01

    We study the potential of highly doped finite carbon nanotubes to serve as plasmonic elements that mediate the interaction between quantum emitters. Similar to graphene, nanotubes support intense plasmons that can be modulated by varying their level of electrical doping. These excitations exhibit large interaction with light and electron beams, as revealed upon examination of the corresponding light extinction cross-section and electron energy-loss spectra. We show that quantum emitters experience record-high Purcell factors, while they undergo strong mutual interaction mediated by their coupling to the tube plasmons. Our results show the potential of doped finite nanotubes as tunable plasmonic materials for quantum optics applications.

  5. Electron spin interactions in chemistry and biology fundamentals, methods, reactions mechanisms, magnetic phenomena, structure investigation

    CERN Document Server

    Likhtenshtein, Gertz

    2016-01-01

    This book presents the versatile and pivotal role of electron spin interactions in nature. It provides the background, methodologies and tools for basic areas related to spin interactions, such as spin chemistry and biology, electron transfer, light energy conversion, photochemistry, radical reactions, magneto-chemistry and magneto-biology. The book also includes an overview of designing advanced magnetic materials, optical and spintronic devices and photo catalysts. This monograph appeals to scientists and graduate students working in the areas related to spin interactions physics, biophysics, chemistry and chemical engineering.

  6. Quantifying electron transfer reactions in biological systems: what interactions play the major role?

    Science.gov (United States)

    Sjulstok, Emil; Olsen, Jógvan Magnus Haugaard; Solov'yov, Ilia A

    2015-12-22

    Various biological processes involve the conversion of energy into forms that are usable for chemical transformations and are quantum mechanical in nature. Such processes involve light absorption, excited electronic states formation, excitation energy transfer, electrons and protons tunnelling which for example occur in photosynthesis, cellular respiration, DNA repair, and possibly magnetic field sensing. Quantum biology uses computation to model biological interactions in light of quantum mechanical effects and has primarily developed over the past decade as a result of convergence between quantum physics and biology. In this paper we consider electron transfer in biological processes, from a theoretical view-point; namely in terms of quantum mechanical and semi-classical models. We systematically characterize the interactions between the moving electron and its biological environment to deduce the driving force for the electron transfer reaction and to establish those interactions that play the major role in propelling the electron. The suggested approach is seen as a general recipe to treat electron transfer events in biological systems computationally, and we utilize it to describe specifically the electron transfer reactions in Arabidopsis thaliana cryptochrome-a signaling photoreceptor protein that became attractive recently due to its possible function as a biological magnetoreceptor.

  7. Quantifying electron transfer reactions in biological systems: what interactions play the major role?

    Science.gov (United States)

    Sjulstok, Emil; Olsen, Jógvan Magnus Haugaard; Solov'Yov, Ilia A.

    2015-12-01

    Various biological processes involve the conversion of energy into forms that are usable for chemical transformations and are quantum mechanical in nature. Such processes involve light absorption, excited electronic states formation, excitation energy transfer, electrons and protons tunnelling which for example occur in photosynthesis, cellular respiration, DNA repair, and possibly magnetic field sensing. Quantum biology uses computation to model biological interactions in light of quantum mechanical effects and has primarily developed over the past decade as a result of convergence between quantum physics and biology. In this paper we consider electron transfer in biological processes, from a theoretical view-point; namely in terms of quantum mechanical and semi-classical models. We systematically characterize the interactions between the moving electron and its biological environment to deduce the driving force for the electron transfer reaction and to establish those interactions that play the major role in propelling the electron. The suggested approach is seen as a general recipe to treat electron transfer events in biological systems computationally, and we utilize it to describe specifically the electron transfer reactions in Arabidopsis thaliana cryptochrome-a signaling photoreceptor protein that became attractive recently due to its possible function as a biological magnetoreceptor.

  8. P ,T -odd electron-nucleus interaction in atomic systems as an exchange by Higgs bosons

    Science.gov (United States)

    Chubukov, D. V.; Labzowsky, L. N.

    2016-06-01

    Scalar-pseudoscalar P ,T -odd interaction between the electron and the nucleus in atomic systems is constructed within the standard model as an exchange by Higgs boson. The necessary P - and T -violating contribution is obtained at the three-loop level on the basis of Cabibbo-Kobayashi-Maskawa matrix. This contribution, unlike the corresponding contribution to the electron electric dipole moment (EDM), does not vanish since the "Higgs charges" of quarks, contrary to their electric charges, are flavor dependent. Order-of-magnitude estimates of the effect expressed as an "equivalent" electron EDM give the values within the range deeqv˜10-40-10-45e cm , depending on the known different estimates for the electron EDM. This can be compared with the known "benchmark" two-photon P ,T -odd electron-nucleus interaction effect, which provides deeqv˜10-38e cm .

  9. Electronic voting to encourage interactive lectures: a randomised trial

    Directory of Open Access Journals (Sweden)

    Palmer Edward

    2007-07-01

    Full Text Available Abstract Background Electronic Voting Systems have been used for education in a variety of disciplines. Outcomes from these studies have been mixed. Because results from these studies have been mixed, we examined whether an EVS system could enhance a lecture's effect on educational outcomes. Methods A cohort of 127 Year 5 medical students at the University of Adelaide was stratified by gender, residency status and academic record then randomised into 2 groups of 64 and 63 students. Each group received consecutive 40-minute lectures on two clinical topics. One group received the EVS for both topics. The other group received traditional teaching only. Evaluation was undertaken with two, 15-question multiple-choice questionnaires (MCQ assessing knowledge and problem solving and undertaken as a written paper immediately before and after the lectures and repeated online 8–12 weeks later. Standardised institutional student questionnaires were completed for each lecture and independent observers assessed student behaviour during the lectures. Lecturer's opinions were assessed by a questionnaire developed for this study. Results Two-thirds of students randomised to EVS and 59% of students randomised to traditional lectures attended. One-half of the students in the EVS group and 41% in the traditional group completed all questionnaires. There was no difference in MCQ scores between EVS and traditional lectures (p = 0.785. The cervical cancer lectures showed higher student ranking in favour of EVS in all parameters. The breast cancer lectures showed higher ranking in favour of traditional lectures in 5 of 7 parameters (p Conclusion In this setting, EVS technology used in large group lectures did not offer significant advantages over the more traditional lecture format.

  10. Theoretical study of ultrarelativistic laser-electron interaction with radiation reaction

    Directory of Open Access Journals (Sweden)

    Seto K.

    2013-11-01

    Full Text Available When the laser intensity becomes higher than 1022  W/cm2, the motion of an electron becomes relativistic, and emits large amounts of radiation. This radiation energy loss transferred to the kinetic energy loss of the electron, is treated as an external force, the “radiation reaction force”. We show the new equation of motion including this radiation reaction and the simulation method, as well as results of single electron system or dual electrons system with Liénard-Wiechert field interaction.

  11. Electron Spin Dephasing and Decoherence by Interaction with Nuclear Spins in Self-Assembled Quantum Dots

    Science.gov (United States)

    Lee, Seungwon; vonAllmen, Paul; Oyafuso, Fabiano; Klimeck, Gerhard; Whale, K. Birgitta

    2004-01-01

    Electron spin dephasing and decoherence by its interaction with nuclear spins in self-assembled quantum dots are investigated in the framework of the empirical tight-binding model. Electron spin dephasing in an ensemble of dots is induced by the inhomogeneous precession frequencies of the electron among dots, while electron spin decoherence in a single dot arises from the inhomogeneous precession frequencies of nuclear spins in the dot. For In(x)Ga(1-x) As self-assembled dots containing 30000 nuclei, the dephasing and decoherence times are predicted to be on the order of 100 ps and 1 (micro)s.

  12. Terahertz radiation emission from plasma beat-wave interactions with a relativistic electron beam

    Science.gov (United States)

    Gupta, D. N.; Kulagin, V. V.; Suk, H.

    2017-10-01

    We present a mechanism to generate terahertz radiation from laser-driven plasma beat-wave interacting with an electron beam. The theory of the energy transfer between the plasma beat-wave and terahertz radiation is elaborated through nonlinear coupling in the presence of a negative-energy relativistic electron beam. An expression of terahertz radiation field is obtained to find out the efficiency of the process. Our results show that the efficiency of terahertz radiation emission is strongly sensitive to the electron beam energy. Emitted field strength of the terahertz radiation is calculated as a function of electron beam velocity.

  13. Analytical Determination of the Confinement Potential and Coupling Constant of Spin--Orbit Interactions of Electrons in Nanostructures

    CERN Document Server

    Dineykhan, M; Zhaugasheva, S A; Al Farabi Kazakh State National University. Almaty

    2005-01-01

    Multilayer nanocrystalline structure is represented by the electrostatic field inducted by total image charge, and the confinement potential for electrons is determined. Assuming that at a given distance the confinement potential is equal to the Coulomb repulsion and an interaction between electrons becomes spin-orbit, the constant of the spin-orbit interaction of electrons in nanostructures is determined. The dependence of the constant of the spin-orbit interaction on environment parameters and the distance between electrons is studied.

  14. Anisotropic Heisenberg form of RKKY interaction in the one-dimensional spin-polarized electron gas

    Science.gov (United States)

    Valizadeh, M. M.

    2016-09-01

    We study the indirect exchange interaction between two localized magnetic moments, known as Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, in a one-dimensional (1D) spin-polarized electron gas. We find explicit expressions for each term of this interaction, study their oscillatory behaviors as a function of the distance between two magnetic moments, R, and compare them with the known results for RKKY interaction in the case of 1D standard electron gas. We show this interaction can be written in an anisotropic Heisenberg form, E(R) = λ2χ xx(S1xS2x + S1yS2y) + λ2χ zzS1zS2z, coming from broken time-reversal symmetry of the host material.

  15. Exploring the Interaction Natures in Plutonyl (VI Complexes with Topological Analyses of Electron Density

    Directory of Open Access Journals (Sweden)

    Jiguang Du

    2016-04-01

    Full Text Available The interaction natures between Pu and different ligands in several plutonyl (VI complexes are investigated by performing topological analyses of electron density. The geometrical structures in both gaseous and aqueous phases are obtained with B3LYP functional, and are generally in agreement with available theoretical and experimental results when combined with all-electron segmented all-electron relativistic contracted (SARC basis set. The Pu– O y l bond orders show significant linear dependence on bond length and the charge of oxygen atoms in plutonyl moiety. The closed-shell interactions were identified for Pu-Ligand bonds in most complexes with quantum theory of atoms in molecules (QTAIM analyses. Meanwhile, we found that some Pu–Ligand bonds, like Pu–OH−, show weak covalent. The interactive nature of Pu–ligand bonds were revealed based on the interaction quantum atom (IQA energy decomposition approach, and our results indicate that all Pu–Ligand interactions is dominated by the electrostatic attraction interaction as expected. Meanwhile it is also important to note that the quantum mechanical exchange-correlation contributions can not be ignored. By means of the non-covalent interaction (NCI approach it has been found that some weak and repulsion interactions existed in plutonyl(VI complexes, which can not be distinguished by QTAIM, can be successfully identified.

  16. Explore Application of Stereo Display System in Virtual Reality%探究立体显示系统在虚拟现实中的运用

    Institute of Scientific and Technical Information of China (English)

    刘小江

    2011-01-01

    论述主、被动立体显示的基本原理,提出虚拟现实中的交互式立体显示系统的架构设计和运用方法.重点阐述基于PC机与专业双屏显卡阵列的大场景立体显示系统的构成要素及原理,并指出与之对应的虚拟场景生成方法,为交互式仿真系统中实现立体显示特别是沙盘立体显示系统给出了解决方案,最后分析比较大场景主、被动立体显示方式优劣及未来发展趋势.%This paper elaborates the fundamentals of active stereo and passive stereo display, and presents the architecture design and methods used for interactive stereo display system of virtual reality. Components and theory of stereo display system are emphasized especially, which is applied to large scene based on pc and professional dual graphics card array. Methods for producing virtual scene are also pointed out. This article offers a solution of achieving stereo display in interactive simulation system especially in sand table stereo display system. Ultimately it compares relative merits of active with passive stereo display methods for large scene and their future trend.

  17. Multi-hypothesis distributed stereo video coding

    DEFF Research Database (Denmark)

    Salmistraro, Matteo; Zamarin, Marco; Forchhammer, Søren

    2013-01-01

    Distributed Video Coding (DVC) is a video coding paradigm that exploits the source statistics at the decoder based on the availability of the Side Information (SI). Stereo sequences are constituted by two views to give the user an illusion of depth. In this paper, we present a DVC decoder...... for stereo sequences, exploiting an interpolated intra-view SI and two inter-view SIs. The quality of the SI has a major impact on the DVC Rate-Distortion (RD) performance. As the inter-view SIs individually present lower RD performance compared with the intra-view SI, we propose multi-hypothesis decoding...... for robust fusion and improved performance. Compared with a state-of-the-art single side information solution, the proposed DVC decoder improves the RD performance for all the chosen test sequences by up to 0.8 dB. The proposed multi-hypothesis decoder showed higher robustness compared with other fusion...

  18. Acceleration of Stereo Correlation in Verilog

    Science.gov (United States)

    Villalpando, Carlos

    2006-01-01

    To speed up vision processing in low speed, low power devices, embedding FPGA hardware is becoming an effective way to add processing capability. FPGAs offer the ability to flexibly add parallel and/or deeply pipelined computation to embedded processors without adding significantly to the mass and power requirements of an embedded system. This paper will discuss the JPL stereo vision system, and describe how a portion of that system was accelerated by using custom FPGA hardware to process the computationally intensive portions of JPL stereo. The architecture described takes full advantage of the ability of an FPGA to use many small computation elements in parallel. This resulted in a 16 times speedup in real hardware over using a simple linear processor to compute image correlation and disparity.

  19. Unwrapping and stereo rectification for omnidirectional images

    Institute of Scientific and Technical Information of China (English)

    Jie LEI; Xin DU; Yun-fang ZHU; Ji-lin LIU

    2009-01-01

    Omnidirectional imaging sensors have been used in more and more applications when a very large field of view is required. In this paper, we investigate the unwrapping, epipolar geometry and stereo rectification issues for omnidirectional vision when the particular mirror model and the camera parameters are unknown in priori. First, the omnidirectional camera is calibrated under the Taylor model, and the parameters related to this model are obtained. In order to make the classical computer vision algorithms of conventional perspective cameras applicable, the ring omnidirectional image is unwrapped into two kinds of panoramas: cylinder and cuboid. Then the epipolar geometry of arbitrary camera configuration is analyzed and the essential matrix is deduced with its properties being indicated for ring images. After that, a simple stereo rectification method based on the essential matrix and the conformal mapping is proposed. Simulations and real data experimental results illustrate that our methods are effective for the omnidirectional camera under the constraint of a single view point.

  20. Interaction of energetic electrons with dust whistler-mode waves in magnetospheric dusty plasmas

    Science.gov (United States)

    Jafari, S.

    2016-04-01

    In this Letter, a new conceptual approach has been presented to investigate the interaction of energetic electrons with dust whistler-mode waves in magnetospheric dusty (complex) plasmas. Dust whistler-mode waves generated in the presence of charged dust grains in the magnetized dusty plasma, can scatter the launched electrons into the loss-cone leading to precipitation into the upper atmosphere which is an important loss process in the radiation belts and provides a major source of energy for the diffuse and pulsating aurora. To study the scattered electrons and chaotic regions, a Hamiltonian model of the electron-dust wave interaction has been employed in the magnetospheric plasma by considering the launched electron beam self-fields. Numerical simulations indicate that an electron beam interacting with the whistler-mode wave can easily trigger chaos in the dust-free plasma, while in the presence of dust charged grains in the plasma, the chaotic regions are quenched to some extent in the magnetosphere. Consequently, the rate of scattered electrons into the loss-cone reduces for the regions that the dust grains are present.

  1. Electron-phonon interaction in three-barrier nanosystems as active elements of quantum cascade detectors

    Energy Technology Data Exchange (ETDEWEB)

    Tkach, N. V., E-mail: ktf@chnu.edu.ua; Seti, Ju. A.; Grynyshyn, Yu. B. [Chernivtsy National University (Ukraine)

    2015-04-15

    The theory of electron tunneling through an open nanostructure as an active element of a quantum cascade detector is developed, which takes into account the interaction of electrons with confined and interface phonons. Using the method of finite-temperature Green’s functions and the electron-phonon Hamiltonian in the representation of second quantization over all system variables, the temperature shifts and electron-level widths are calculated and the contributions of different electron-phonon-interaction mechanisms to renormalization of the spectral parameters are analyzed depending on the geometrical configuration of the nanosystem. Due to weak electron-phonon coupling in a GaAs/Al{sub 0.34}Ga{sub 0.66}As-based resonant tunneling nanostructure, the temperature shift and rf field absorption peak width are not very sensitive to the electron-phonon interaction and result from a decrease in potential barrier heights caused by a difference in the temperature dependences of the well and barrier band gaps.

  2. Nonlinear dynamics of electrons interacting with oblique whistler mode chorus in the magnetosphere

    Science.gov (United States)

    Hsieh, Yi-Kai; Omura, Yoshiharu

    2017-01-01

    We perform test particle simulations for relativistic electrons interacting with a whistler mode chorus packet propagating at oblique angles. By confirming that the energy transport of oblique lower band chorus is nearly along the ambient magnetic field, we apply the gyroaveraging method in calculating equations of motion of electrons. We trace evolution of a delta function of relativistic electrons in a phase space of kinetic energy and equatorial pitch angle and obtain numerical Green's functions of the chorus wave-particle interactions. Examining the Green's functions in a wide range of kinetic energies, we find that Landau resonance can accelerate MeV electrons efficiently and that higher nth resonances such as n =- 1 and n = 2 also contribute to acceleration of electrons at high equatorial pitch angles (˜70°) and high energies (˜2 MeV). We investigate the rate of energy gain of the cyclotron resonance acceleration and the Landau resonance acceleration and find that the perpendicular component of wave electric field dominates both accelerations for MeV electrons. Furthermore, the proximity between the parallel components of Vp and Vg of oblique whistler mode waves and the nonlinear trapping condition make the interaction time of Landau resonance much longer than that of n = 1 cyclotron resonance, resulting in efficient acceleration of MeV electrons.

  3. Spin-polarized free electron beam interaction with radiation and superradiant spin-flip radiative emission

    Directory of Open Access Journals (Sweden)

    A. Gover

    2006-06-01

    Full Text Available The problems of spin-polarized free-electron beam interaction with electromagnetic wave at electron-spin resonance conditions in a magnetic field and of superradiant spin-flip radiative emission are analyzed in the framework of a comprehensive classical model. The spontaneous emission of spin-flip radiation from electron beams is very weak. We show that the detectivity of electron spin resonant spin-flip and combined spin-flip/cyclotron-resonance-emission radiation can be substantially enhanced by operating with ultrashort spin-polarized electron beam bunches under conditions of superradiant (coherent emission. The proposed radiative spin-state modulation and the spin-flip radiative emission schemes can be used for control and noninvasive diagnostics of polarized electron/positron beams. Such schemes are of relevance in important scattering experiments off nucleons in nuclear physics and off magnetic targets in condensed matter physics.

  4. Screened test-charge - electron interaction including many-body effects in two and three dimensions

    Science.gov (United States)

    Gold, A.; Ghazali, A.

    1997-05-01

    Bound states of a negatively charged test particle and an electron are studied by incorporating many-body effects (exchange and correlation) in the screening function of an interacting electron gas via the local-field correction. Using a variational method and a matrix-diagonalization method we determine the energies and the wave functions of the ground state and the excited states as functions of the electron density for three-dimensional and two-dimensional systems. For high electron density no bound states are found. Below a critical density the number and the energy of the bound states increase with decreasing electron density. We also present results for bound-state energies of a positively charged test particle with an electron, and compare them with results obtained within the random-phase approximation where the local-field correction is ignored.

  5. Electron heating in subpicosecond laser interaction with overdense and near-critical plasmas

    Science.gov (United States)

    Cialfi, L.; Fedeli, L.; Passoni, M.

    2016-11-01

    In this work we investigate electron heating induced by intense laser interaction with micrometric flat solid foils in the context of laser-driven ion acceleration. We propose a simple law to predict the electron temperature in a wider range of laser parameters with respect to commonly used existing models. An extensive two-dimensional (2D) and 3D numerical campaign shows that electron heating is due to the combined actions of j ×B and Brunel effect. Electron temperature can be well described with a simple function of pulse intensity and angle of incidence, with parameters dependent on pulse polarization. We then combine our model for the electron temperature with an existing model for laser-ion acceleration, using recent experimental results as a benchmark. We also discuss an exploratory attempt to model electron temperature for multilayered foam-attached targets, which have been proven recently to be an attractive target concept for laser-driven ion acceleration.

  6. Critical factors in SEM 3D stereo microscopy

    DEFF Research Database (Denmark)

    Marinello, F.; Bariano, P.; Savio, E.;

    2008-01-01

    This work addresses dimensional measurements performed with the scanning electron microscope (SEM) using 3D reconstruction of surface topography through stereo-photogrammetry. The paper presents both theoretical and experimental investigations, on the effects of instrumental variables...... factors are recognized: the first one is related to the measurement operation and the instrument set-up; the second concerns the quality of scanned images and represents the major criticality in the application of SEMs for 3D characterizations....... and measurement parameters on reconstruction accuracy. Investigations were performed on a novel sample, specifically developed and implemented for the tests. The description is based on the model function introduced by Piazzesi and adapted for eucentrically tilted stereopairs. Two main classes of influencing...

  7. The analogy between stereo depth and brightness.

    Science.gov (United States)

    Brookes, A; Stevens, K A

    1989-01-01

    Apparent depth in stereograms exhibits various simultaneous-contrast and induction effects analogous to those reported in the luminance domain. This behavior suggests that stereo depth, like brightness, is reconstructed, ie recovered from higher-order spatial derivatives or differences of the original signal. The extent to which depth is analogous to brightness is examined. There are similarities in terms of contrast effects but dissimilarities in terms of the lateral inhibition effects traditionally attributed to underlying spatial-differentiation operators.

  8. Stereo cameras on the International Space Station

    Science.gov (United States)

    Sabbatini, Massimo; Visentin, Gianfranco; Collon, Max; Ranebo, Hans; Sunderland, David; Fortezza, Raimondo

    2007-02-01

    Three-dimensional media is a unique and efficient means to virtually visit/observe objects that cannot be easily reached otherwise, like the International Space Station. The advent of auto-stereoscopic displays and stereo projection system is making the stereo media available to larger audiences than the traditional scientists and design engineers communities. It is foreseen that a major demand for 3D content shall come from the entertainment area. Taking advantage of the 6 months long permanence on the International Space Station of a colleague European Astronaut, Thomas Reiter, the Erasmus Centre uploaded to the ISS a newly developed, fully digital stereo camera, the Erasmus Recording Binocular. Testing the camera and its human interfaces in weightlessness, as well as accurately mapping the interior of the ISS are the main objectives of the experiment that has just been completed at the time of writing. The intent of this paper is to share with the readers the design challenges tackled in the development and operation of the ERB camera and highlight some of the future plans the Erasmus Centre team has in the pipeline.

  9. The dipole moment of the electron carrier adrenodoxin is not critical for redox partner interaction and electron transfer.

    Science.gov (United States)

    Hannemann, Frank; Guyot, Arnaud; Zöllner, Andy; Müller, Jürgen J; Heinemann, Udo; Bernhardt, Rita

    2009-07-01

    Dipole moments of proteins arise from helical dipoles, hydrogen bond networks and charged groups at the protein surface. High protein dipole moments were suggested to contribute to the electrostatic steering between redox partners in electron transport chains of respiration, photosynthesis and steroid biosynthesis, although so far experimental evidence for this hypothesis was missing. In order to probe this assumption, we changed the dipole moment of the electron transfer protein adrenodoxin and investigated the influence of this on protein-protein interactions and electron transfer. In bovine adrenodoxin, the [2Fe-2S] ferredoxin of the adrenal glands, a dipole moment of 803 Debye was calculated for a full-length adrenodoxin model based on the Adx(4-108) and the wild type adrenodoxin crystal structures. Large distances and asymmetric distribution of the charged residues in the molecule mainly determine the observed high value. In order to analyse the influence of the resulting inhomogeneous electric field on the biological function of this electron carrier the molecular dipole moment was systematically changed. Five recombinant adrenodoxin mutants with successively reduced dipole moment (from 600 to 200 Debye) were analysed for their redox properties, their binding affinities to the redox partner proteins and for their function during electron transfer-dependent steroid hydroxylation. None of the mutants, not even the quadruple mutant K6E/K22Q/K24Q/K98E with a dipole moment reduced by about 70% showed significant changes in the protein function as compared with the unmodified adrenodoxin demonstrating that neither the formation of the transient complex nor the biological activity of the electron transfer chain of the endocrine glands was affected. This is the first experimental evidence that the high dipole moment observed in electron transfer proteins is not involved in electrostatic steering among the proteins in the redox chain.

  10. Azimuthal asymmetry in collective electron dynamics in relativistically transparent laser-foil interactions

    Science.gov (United States)

    Gray, R. J.; MacLellan, D. A.; Gonzalez-Izquierdo, B.; Powell, H. W.; Carroll, D. C.; Murphy, C. D.; Stockhausen, L. C.; Rusby, D. R.; Scott, G. G.; Wilson, R.; Booth, N.; Symes, D. R.; Hawkes, S. J.; Torres, R.; Borghesi, M.; Neely, D.; McKenna, P.

    2014-09-01

    Asymmetry in the collective dynamics of ponderomotively-driven electrons in the interaction of an ultraintense laser pulse with a relativistically transparent target is demonstrated experimentally. 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 transparency, to a double-lobe structure aligned perpendicular to it when a significant fraction of the laser pulse co-propagates with the electrons. The temporally-resolved dynamics of the interaction are investigated via particle-in-cell simulations. The results provide new insight into the collective response of charged particles to intense laser fields over an extended interaction volume, which is important for a wide range of applications, and in particular for the development of promising new ultraintense laser-driven ion acceleration mechanisms involving ultrathin target foils.

  11. Interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening

    Science.gov (United States)

    Martín-Solís, J. R.; Sánchez, R.; Esposito, B.

    2002-05-01

    Due to the relativistic decrease of the electron cyclotron frequency, a cyclotron resonance may appear between runaway electrons and lower hybrid waves. A single particle description of the runaway dynamics [J. R. Martín-Solís et al., Phys. Plasmas 5, 2370 (1998)] is extended to analyze the effect of the interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening. The conditions under which the resonant interaction can play a role in limiting the runaway energy are established and it is shown that, under typical lower hybrid current drive operation parameters, an efficient wave-particle coupling may occur. Observations of a fast pitch angle scattering event during the current decay phase of Ohmic discharges in the Toroidal Experiment for Technically Oriented Research (TEXTOR) [R. J. E. Jaspers, Ph.D. thesis, Technical University Eindhoven (1995)] are interpreted in terms of such interaction.

  12. Latest progress on interactions between VLF/ELF waves and energetic electrons in the inner magnetosphere

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Interactions between very/extremely low frequency (VLF/ELF) waves and energetic electrons play a fundamental role in dynamics occurring in the inner magnetosphere. Here, we briefly discuss global properties of VLF/ELF waves, along with the variability of the electron radiation belts associated with wave-particle interactions and radial diffusion. We provide cases of electron loss and acceleration as a result of wave-particle interactions primarily due to such waves, and particularly some preliminary results of 3D evolution of phase space density from our currently developing 3D code. We comment on the existing mechanisms responsible for acceleration and loss, and identify several critical issues that need to be addressed. We review latest progress and suggest open questions for future investigation.

  13. Influence of the curve density relative electron in dosimetry clinic in treatments stereo tactics; Influencia de la curva de densidad electronica relativa en la dosimetria clinica en tratamientos estereotaxicos

    Energy Technology Data Exchange (ETDEWEB)

    Moreno Saiz, C.; Benitez Villegas, E. M.; Casado Villalon, F. J.; Parra Osorio, V.; Bodineau Gil, C.; Garcia Pareja, S.

    2013-07-01

    The objective of this study is to analyze the difference between clinical dosimetry in the treatments with radiosurgery and stereotactic radiotherapy fractional obtained from the relative Electron density curve (Schneider 1996) tabulated and provided with the scanner's radiation therapy. (Author)

  14. Two new macro-stereo cameras for medical photography with special reference to the eye.

    Science.gov (United States)

    AandeKerk, A L

    1991-04-01

    Information is given on two new macro-stereo cameras for simultaneous stereo photography designed by members of the Dutch Stereo Society. These cameras can be used for medical photography. The first camera takes half frame stereo pictures and utilizes frames for positioning and focusing. The second camera takes full frame stereo pictures and utilizes spots projection for positioning and focusing. Examples are shown.

  15. Electronic metal-support interaction enhanced oxygen reduction activity and stability of boron carbide supported platinum

    Science.gov (United States)

    Jackson, Colleen; Smith, Graham T.; Inwood, David W.; Leach, Andrew S.; Whalley, Penny S.; Callisti, Mauro; Polcar, Tomas; Russell, Andrea E.; Levecque, Pieter; Kramer, Denis

    2017-06-01

    Catalysing the reduction of oxygen in acidic media is a standing challenge. Although activity of platinum, the most active metal, can be substantially improved by alloying, alloy stability remains a concern. Here we report that platinum nanoparticles supported on graphite-rich boron carbide show a 50-100% increase in activity in acidic media and improved cycle stability compared to commercial carbon supported platinum nanoparticles. Transmission electron microscopy and x-ray absorption fine structure analysis confirm similar platinum nanoparticle shapes, sizes, lattice parameters, and cluster packing on both supports, while x-ray photoelectron and absorption spectroscopy demonstrate a change in electronic structure. This shows that purely electronic metal-support interactions can significantly improve oxygen reduction activity without inducing shape, alloying or strain effects and without compromising stability. Optimizing the electronic interaction between the catalyst and support is, therefore, a promising approach for advanced electrocatalysts where optimizing the catalytic nanoparticles themselves is constrained by other concerns.

  16. Optical vibration modes and electron-phonon interaction in ternary mixed crystals of polar semiconductors

    Institute of Scientific and Technical Information of China (English)

    Liang Xi-Xia; Ban Shi-Liang

    2004-01-01

    @@ Optical vibrations of the lattice and the electron-phonon interaction in polar ternary mixed crystals are studied in the framework of the continuum model of Born and Huang and the random-element-isodisplacement model. A normal-coordinate system to describe the optical vibration in ternary mixed crystals is correctly adopted to derive a new Frohlich-like Hamiltonian for the electron-phonon interaction including the unit-cell volume variation influence.The numerical results for the phonon modes, the electron-phonon coupling constants and the polaronic energies for several typical materials are obtained. It is verified that the nonlinearity of the electron-phonon coupling effects with the composition is essential and the unit-cell volume effects cannot be neglected for most ternary mixed crystals.

  17. Interactions between energetic electrons and realistic whistler mode waves in the Jovian magnetosphere

    Science.gov (United States)

    de Soria-Santacruz, M.; Shprits, Y. Y.; Drozdov, A.; Menietti, J. D.; Garrett, H. B.; Zhu, H.; Kellerman, A. C.; Horne, R. B.

    2017-05-01

    The role of plasma waves in shaping the intense Jovian radiation belts is not well understood. In this study we use a realistic wave model based on an extensive survey from the Plasma Wave Investigation on the Galileo spacecraft to calculate the effect of pitch angle and energy diffusion on Jovian energetic electrons due to upper and lower band chorus. Two Earth-based models, the Full Diffusion Code and the Versatile Electron Radiation Belt code, are adapted to the case of the Jovian magnetosphere and used to resolve the interaction between chorus and electrons at L = 10. We also present a study of the sensitivity to the latitudinal wave coverage and initial electron distribution. Our analysis shows that the contribution to the electron dynamics from upper band chorus is almost negligible compared to that from lower band chorus. For 100 keV electrons, we observe that diffusion leads to redistribution of particles toward lower pitch angles with some particle loss, which could indicate that radial diffusion or interchange instabilities are important. For energies above >500 keV, an initial electron distribution based on observations is only weakly affected by chorus waves. Ideally, we would require the initial electron phase space density before transport takes place to assess the importance of wave acceleration, but this is not available. It is clear from this study that the shape of the electron phase space density and the latitudinal extent of the waves are important for both electron acceleration and loss.

  18. Investigating the differences between electron and muon neutrino interactions using the T2K near detector

    CERN Document Server

    Lamont, Iain

    2015-01-01

    The T2K neutrino beam consists mostly of muon neutrinos with a 1$\\%$ component of electron neutrinos. In order to maximise the physics potential of T2K and other future neutrino experiments, it is important to understand how these electron and muon neutrinos interact. To this end, the ratio of the Charged-Current Quasi-Elastic (CCQE) cross section to the total Charged Current (CC) cross section is taken for both $\

  19. To the Question of the Efficiency of the Electron-Phonon Interaction in Lead Iodide Nanofilms

    Directory of Open Access Journals (Sweden)

    O.V. Pugantseva

    2014-01-01

    Full Text Available The question of the efficiency of the electron-phonon interaction in the formation of the electron, hole, and exciton energy spectrum in 2H-PbI2 semiconductor flat nanofilm is discussed. Based on the analysis of the theoretical calculation results of the bottom of the exciton energy band and its temperature dependence in nanofilms of different thickness, the optimal set of theory parameters which provides its agreement with the experimental measurement data is determined.

  20. Interaction of a Surface Acoustic Wave with a Two-dimensional Electron Gas

    Institute of Scientific and Technical Information of China (English)

    YANG Shi-Jie; ZHAO Hu; YU Yue

    2005-01-01

    When a surface acoustic wave (SAW) propagates on the surface of a GaAs semiconductor, coupling between electrons in the two-dimensional electron gas beneath the interface and the elastic host crystal through piezoelectric interaction will attenuate the SAW. The coupling coefficient is calculated for the SAW propagating along an arbitrary direction. It is found that the coupling strength is strongly dependent on the propagating direction. When the SAW propagates along the [011] direction, the coupling becomes quite weak.

  1. Electron–electron interactions and the electrical resistivity of lithium at low temperatures

    Indian Academy of Sciences (India)

    O N Awasthi; V K Pundhir

    2007-01-01

    The electron–electron interactions in lithium metal have been examined keeping in view the recent developments. The contribution of the electron–electron Umklapp scattering processes in the electrical resistivity of lithium at low temperatures has been evaluated using a simplified spherical Fermi surface model with isotropic transition probability. Our values of the electrical resistivity so obtained compare fairly well with the experimental results for lithium.

  2. A Perylene-Based Microporous Coordination Polymer Interacts Selectively with Electron-Poor Aromatics.

    Science.gov (United States)

    Tran, Ly D; Ma, Jialiu; Wong-Foy, Antek G; Matzger, Adam J

    2016-04-11

    The design, synthesis, and properties of the new microporous coordination polymer UMCM-310 are described. The unique electronic character of the perylene-based linker enables selective interaction with electron-poor aromatics leading to efficient separation of nitroaromatics. UMCM-310 possesses high surface area and large pore size and thus permits the separation of large organic molecules based on adsorption rather than size exclusion.

  3. Excitation of hydrogen atoms in collisions with helium atoms: the role of electron–electron interaction

    Science.gov (United States)

    Frémont, F.; Belyaev, A. K.

    2017-02-01

    Cross sections for producing H(nl) excited state atoms in H(1s) + He(1s2) collisions are calculated using the CTMC method, at impact energies ranging from 20 eV to 100 keV. The role of the electron correlation is studied. In the first step, the interactions between each pair of the three electrons are neglected. This leads to disagreement of the calculated total cross section for producing H(2l) atoms with previous experimental and theoretical results. In a second step, the electron–electron interaction is taken into account in a rigorous way, that is, in the form of the pure Coulomb potential. To make sure that the He target is stable before the collision, phenomenological potentials for the electron–helium-nucleus interactions that simulate the Heisenberg principle are included in addition to the Coulomb potential. The excitation cross section calculated in the frame of this model is in remarkable agreement with previous data in the range between 200 eV and 5 keV. At other energies, discrepancies are revealed, but only by a factor of less than 2 at high energies. The present results show the decisive role of the electron–electron interaction during collisions. In addition, they demonstrate the ability of classical mechanics to take into account the effects of the electron correlation.

  4. Study of hot electrons generated from intense laser-plasma interaction employing Image Plate

    Institute of Scientific and Technical Information of China (English)

    LIANG WenXi; JIN Zhan; WEI ZhiYi; ZHAO Wei; LI YingJun; ZHANG Jie; LI YuTong; XU MiaoHua; YUAN XiaoHui; ZHENG ZhiYuan; ZHANG Yi; LIU Feng; WANG ZhaoHua; LI HanMing

    2008-01-01

    Image Plate (IP) is convenient to be used and very suitable for radiation detection because of its advantages such as wide dynamic range, high detective quantum efficiency, ultrahigh sensitivity and superior linearity. The function mechanism and characteristics of IP are introduced in this paper. IP was employed in the study of hot electrons generated from intense laser-plasma interaction. The angular distri-bution and energy spectrum of hot electrons were measured with IP in the experi-ments. The results demonstrate that IP is an effective radiation detector for the study of laser-plasma interaction.

  5. Study of hot electrons generated from intense laser-plasma interaction employing Image Plate

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Image Plate (IP) is convenient to be used and very suitable for radiation detection because of its advantages such as wide dynamic range, high detective quantum efficiency, ultrahigh sensitivity and superior linearity. The function mechanism and characteristics of IP are introduced in this paper. IP was employed in the study of hot electrons generated from intense laser-plasma interaction. The angular distri- bution and energy spectrum of hot electrons were measured with IP in the experi- ments. The results demonstrate that IP is an effective radiation detector for the study of laser-plasma interaction.

  6. Electron-phonon interaction and pairing mechanism in superconducting Ca-intercalated bilayer graphene

    Science.gov (United States)

    Margine, E. R.; Lambert, Henry; Giustino, Feliciano

    2016-01-01

    Using the ab initio anisotropic Eliashberg theory including Coulomb interactions, we investigate the electron-phonon interaction and the pairing mechanism in the recently-reported superconducting Ca-intercalated bilayer graphene. We find that C6CaC6 can support phonon-mediated superconductivity with a critical temperature Tc = 6.8–8.1 K, in good agreement with experimental data. Our calculations indicate that the low-energy Caxy vibrations are critical to the pairing, and that it should be possible to resolve two distinct superconducting gaps on the electron and hole Fermi surface pockets. PMID:26892805

  7. Interactions in 2D electron and hole systems in the intermediate and ballistic regimes

    Energy Technology Data Exchange (ETDEWEB)

    Proskuryakov, Y Y [School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL (United Kingdom); Savchenko, A K [School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL (United Kingdom); Safonov, S S [School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL (United Kingdom); Li, L [School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL (United Kingdom); Pepper, M [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Simmons, M Y [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Ritchie, D A [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Linfield, E H [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Kvon, Z D [Institute of Semiconductor Physics, Novosibirsk, 630090 (Russian Federation)

    2003-09-05

    In different 2D semiconductor systems we study the interaction correction to the Drude conductivity in the intermediate and ballistic regimes, where the parameter k{sub B}T{tau}/ h-bar changes from 0.1 to 10 ({tau} is momentum relaxation time). The temperature dependence of the resistance and magnetoresistance in parallel and perpendicular magnetic fields is analysed in terms of the recent theories of electron-electron interactions in systems with different degree of disorder and different character of the fluctuation potential. Generally, good agreement is found between the experiments and the theories.

  8. Time-dependent restricted active space Configuration Interaction for the photoionization of many-electron atoms

    CERN Document Server

    Hochstuhl, David

    2012-01-01

    We introduce the time-dependent restricted active space Configuration Interaction method to solve the time-dependent Schr\\"odinger equation for many-electron atoms, and particularly apply it to the treatment of photoionization processes in atoms. The method is presented in a very general formulation and incorporates a wide range of commonly used approximation schemes, like the single-active electron approximation, time-dependent Configuration Interaction with single-excitations, or the time-dependent R-matrix method. We proof the applicability of the method by calculating the photoionization cross sections of Helium and Beryllium.

  9. Electroweak interactions between intense neutrino beams and dense electron-positron magneto-plasmas

    CERN Document Server

    Tsintsadze, N L; Stenflo, L

    2003-01-01

    The electroweak coupling between intense neutrino beams and strongly degenerate relativistic dense electron-positron magneto-plasmas is considered. The intense neutrino bursts interact with the plasma due to the weak Fermi interaction force, and their dynamics is governed by a kinetic equation. Our objective here is to develop a kinetic equation for a degenerate neutrino gas and to use that equation to derive relativistic magnetohydrodynamic equations. The latter are useful for studying numerous collective processes when intense neutrino beams nonlinearly interact with degenerate, relativistic, dense electron-positron plasmas in strong magnetic fields. If the number densities of the plasma particles are of the order of 10 sup 3 sup 3 cm sup - sup 3 , the pair plasma becomes ultra-relativistic, which strongly affects the potential energy of the weak Fermi interaction. The new system of equations allows several neutrino-driven streaming instabilities involving new types of relativistic Alfven-like waves, The re...

  10. High Harmonic Inverse Free-Electron-Laser Interaction at 800nm

    Energy Technology Data Exchange (ETDEWEB)

    Sears, Christopher M.S.; Colby, Eric; Cowan, Ben; Siemann, Robert H.; Spencer, James; /SLAC; Byer, Robert L.; Plettner, Tomas; /Stanford U., Phys. Dept.

    2005-05-13

    The inverse Free Electron Laser (IFEL) interaction has recently been proposed and used as a short wavelength modulator for micro bunching of beams for laser acceleration experiments [1,2]. These experiments utilized the fundamental of the interaction between the laser field and electron bunch. In the current experiment, we explore the higher order resonances of the IFEL interaction from a 3 period, 1.8 centimeter wavelength undulator with a picosecond, 0.5 mJ/pulse laser at 800nm. The resonances are observed by adjusting the gap of the undulator while keeping the beam energy constant. We also compare the experimental results to a simple analytic model that describes coupling to high order harmonics of the interaction.

  11. High-Harmonic Inverse Free-Electron-Laser Interaction at 800nm

    Energy Technology Data Exchange (ETDEWEB)

    Sears, C

    2006-02-17

    The inverse Free Electron Laser (IFEL) interaction has recently been proposed and used as a short wavelength modulator for micro bunching of beams for laser acceleration experiments [1,2]. These experiments utilized the fundamental of the interaction between the laser field and electron bunch. In the current experiment, we explore the higher order resonances of the IFEL interaction from a 3 period, 1.8 centimeter wavelength undulator with a picosecond, 0.5 mJ/pulse laser at 800nm. The resonances are observed by adjusting the gap of the undulator while keeping the beam energy constant. We also compare the experimental results to a simple analytic model that describes coupling to high order harmonics of the interaction.

  12. Lossless Compression of Stereo Disparity Maps for 3D

    DEFF Research Database (Denmark)

    Zamarin, Marco; Forchhammer, Søren

    2012-01-01

    Efficient compression of disparity data is important for accurate view synthesis purposes in multi-view communication systems based on the “texture plus depth” format, including the stereo case. In this paper a novel technique for lossless compression of stereo disparity images is presented...... disparity maps for stereo pairs and outperforms different standard solutions for lossless still image compression. Moreover, it provides a progressive representation of disparity data as well as a parallelizable structure....

  13. Interactivity between protégés and scientists in an electronic mentoring program

    OpenAIRE

    Bonnett, C.; Wildemuth, B.; Sonnenwald, D. H.

    2006-01-01

    Interactivity is defined by Henri (1992) as a three-step process involving communication of information, a response to this information, and a reply to that first response. It is a key dimension of computer-mediated communication, particularly in the one-on-one communication involved in an electronic mentoring program. This report analyzes the interactivity between pairs of corporate research scientists (mentors) and university biology students (protégés) during two consecutive implementation...

  14. Electron Dynamics During High-Power, Short-Pulsed Laser Interactions with Solids and Interfaces

    Science.gov (United States)

    2016-06-28

    PAPER ALSO RECEIVED EXTERNAL MEDIA COVERENCE FROM SIGNAL MAGAZINE : http://www.afcea.org/content/?q=Article-scientists-harness- energy -heat Edited...AFRL-AFOSR-VA-TR-2016-0234 Electron Dynamics During High- Power , Short-Pulsed Laser Interactions with Solids and Interfaces Patrick Hopkins...Dynamics During High- Power , Short-Pulsed Laser Interactions with Solids and Interfaces 5a. CONTRACT NUMBER FA9550-13-1-0067 5b. GRANT NUMBER 5c

  15. High flux, narrow bandwidth compton light sources via extended laser-electron interactions

    Science.gov (United States)

    Barty, V P

    2015-01-13

    New configurations of lasers and electron beams efficiently and robustly produce high flux beams of bright, tunable, polarized quasi-monoenergetic x-rays and gamma-rays via laser-Compton scattering. Specifically, the use of long-duration, pulsed lasers and closely-spaced, low-charge and low emittance bunches of electron beams increase the spectral flux of the Compton-scattered x-rays and gamma rays, increase efficiency of the laser-electron interaction and significantly reduce the overall complexity of Compton based light sources.

  16. Plasmon-terahertz photon interaction in high-electron-mobility heterostructures

    Science.gov (United States)

    Łusakowski, Jerzy

    2017-01-01

    Terahertz (THz) radiation couples to a two-dimensional electron plasma in high-electron-mobility heterostructures which allows one to study fundamental properties of this electron system and construct plasma-based devices. This article reviews some of the recent results of theoretical and experimental studies on plasmon-THz photon interaction. In particular, plasma dispersion relations, mechanisms of THz-field rectification and ultrastrong light-matter coupling are discussed in conventional structures based on GaAs and CdTe and new materials—graphene and black phosphorus.

  17. Electromagnetic microwaves in metal films with electron-phonon interaction and a dc magnetic field

    DEFF Research Database (Denmark)

    Hasselberg, L.E.

    1976-01-01

    A quantum-mechanical treatment of electromagnetic microwaves is performed for a metal film. The directions of the exterior ac and dc fields are taken to be arbitrary and boundary conditions for the electrons are assumed to be specular. The relation between the current and the electromagnetic field...... becomes nonlocal both in ordinary and Fourier space. An expression for the electron self-energy is introduced, which includes electron-phonon interaction and an effective relaxation time. The theory is applied to cyclotron phase resonance in potassium. It is suggested that the experimental peak structure...

  18. A focusable, convergent fast-electron beam from ultra-high-intensity laser-solid interactions

    CERN Document Server

    Scott, R H H

    2015-01-01

    A novel scheme for the creation of a convergent, or focussing, fast-electron beam generated from ultra-high-intensity laser-solid interactions is described. Self-consistent particle-in-cell simulations are used to demonstrate the efficacy of this scheme in two dimensions. It is shown that a beam of fast-electrons of energy 500 keV - 3 MeV propagates within a solid-density plasma, focussing at depth. The depth of focus of the fast-electron beam is controlled via the target dimensions and focussing optics.

  19. Electron emission induced by resonant coherent ion-surface interaction at grazing incidence

    Energy Technology Data Exchange (ETDEWEB)

    Garcia de Abajo, F.J. (Departamento de Ciencias de la Computacion e Inteligencia Artificial, Facultad de Informatica, Universidad del Pais Vasco, Apartado 649, 20080 San Sebastian (Spain)); Ponce, V.H. (Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 San Carlos de Bariloche, Rio Negro (Argentina)); Echenique, P.M. (Departamento de Fisica de Materiales, Facultad de Quimica, Universidad del Pais Vasco, Apartado 1072, 20080 San Sebastian (Spain))

    1992-10-19

    A new spectroscopy based on the resonant coherently induced electron loss to the continuum in ion-surface scattering under grazing incidence is proposed. A series of peaks, corresponding to the energy differences determined by the resonant interaction with the rows of atoms in the surface, is predicted to appear in the energy distribution of electrons emitted from electronic states bound to the probe. Calculations for MeV He{sup +} ions scattered at a W(001) surface along the {l angle}100{r angle} direction with a glancing angle of 0--2 mrad show a total yield close to 1.

  20. Transverse and longitudinal characterization of electron beams using interaction with optical near-fields

    CERN Document Server

    Kozák, Martin; Leedle, Kenneth J; Deng, Huiyang; Schönenberger, Norbert; Ruehl, Axel; Hartl, Ingmar; Hoogland, Heinar; Holzwarth, Ronald; Harris, James S; Byer, Robert L; Hommelhoff, Peter

    2016-01-01

    We demonstrate an experimental technique for both transverse and longitudinal characterization of bunched femtosecond free electron beams. The operation principle is based on monitoring of the current of electrons that obtained an energy gain during the interaction with the synchronized optical near-field wave excited by femtosecond laser pulses. The synchronous accelerating/decelerating fields confined to the surface of a silicon nanostructure are characterized using a highly focused sub-relativistic electron beam. Here the transverse spatial resolution of 450 nm and femtosecond temporal resolution achievable by this technique are demonstrated.

  1. Effect of electron-phonon interaction on resistivity of some heavy fermion (HF) systems

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, J., E-mail: jitendrasahoo2008@gmail.com [Assistant Director, Regional Office of Vocational Education, Sambalpur, Odisha-768004 (India); Shadangi, N. [Dept. of Physics, Silicon Institute of Technology, Sambalpur, Odisha-768200 (India); Nayak, P. [School of Physics, Sambalpur University, Sambalpur, Odisha-768019 (India)

    2014-04-24

    Here, we have analyzed the electron-phonon interaction in the Periodic Anderson Model (PAM) to describe the temperature dependence of resistivity in some heavy fermion (HF) systems for finite wave vector (q) and for finite temperature (T). Since the resistivity is related to the imaginary part of the electron self energy, the expression for the same is evaluated through double time temperature dependant Green function technique of the Zubarev type. The effect of different system parameters namely the position of 4f level, E{sub 0} and the electron - phonon coupling strengths on resistivity have been studied. The results obtained give satisfactory explanations to the experimental observations.

  2. Interaction studies between periplasmic cytochromes provide insights into extracellular electron transfer pathways of Geobacter sulfurreducens.

    Science.gov (United States)

    Fernandes, Ana P; Nunes, Tiago C; Paquete, Catarina M; Salgueiro, Carlos A

    2017-02-20

    Geobacter bacteria usually prevail among other microorganisms in soils and sediments where Fe(III) reduction has a central role. This reduction is achieved by extracellular electron transfer (EET), where the electrons are exported from the interior of the cell to the surrounding environment. Periplasmic cytochromes play an important role in establishing an interface between inner and outer membrane electron transfer components. In addition, periplasmic cytochromes, in particular nanowire cytochromes that contain at least 12 haem groups, have been proposed to play a role in electron storage in conditions of an environmental lack of electron acceptors. Up to date, no redox partners have been identified in Geobacter sulfurreducens, and concomitantly, the EET and electron storage mechanisms remain unclear. In this work, NMR chemical shift perturbation measurements were used to probe for an interaction between the most abundant periplasmic cytochrome PpcA and the dodecahaem cytochrome GSU1996, one of the proposed nanowire cytochromes in G. sulfurreducens The perturbations on the haem methyl signals of GSU1996 and PpcA showed that the proteins form a transient redox complex in an interface that involves haem groups from two different domains located at the C-terminal of GSU1996. Overall, the present study provides for the first time a clear evidence for an interaction between periplasmic cytochromes that might be relevant for the EET and electron storage pathways in G. sulfurreducens. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  3. Hybrid Simulation of Laser-Plasma Interactions and Fast Electron Transport in Inhomogeneous Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, B I; Kemp, A; Divol, L

    2009-05-27

    A new framework is introduced for kinetic simulation of laser-plasma interactions in an inhomogenous plasma motivated by the goal of performing integrated kinetic simulations of fast-ignition laser fusion. The algorithm addresses the propagation and absorption of an intense electromagnetic wave in an ionized plasma leading to the generation and transport of an energetic electron component. The energetic electrons propagate farther into the plasma to much higher densities where Coulomb collisions become important. The high-density plasma supports an energetic electron current, return currents, self-consistent electric fields associated with maintaining quasi-neutrality, and self-consistent magnetic fields due to the currents. Collisions of the electrons and ions are calculated accurately to track the energetic electrons and model their interactions with the background plasma. Up to a density well above critical density, where the laser electromagnetic field is evanescent, Maxwell's equations are solved with a conventional particle-based, finite-difference scheme. In the higher-density plasma, Maxwell's equations are solved using an Ohm's law neglecting the inertia of the background electrons with the option of omitting the displacement current in Ampere's law. Particle equations of motion with binary collisions are solved for all electrons and ions throughout the system using weighted particles to resolve the density gradient efficiently. The algorithm is analyzed and demonstrated in simulation examples. The simulation scheme introduced here achieves significantly improved efficiencies.

  4. Calibration of a Stereo Radiation Detection Camera Using Planar Homography

    Directory of Open Access Journals (Sweden)

    Seung-Hae Baek

    2016-01-01

    Full Text Available This paper proposes a calibration technique of a stereo gamma detection camera. Calibration of the internal and external parameters of a stereo vision camera is a well-known research problem in the computer vision society. However, few or no stereo calibration has been investigated in the radiation measurement research. Since no visual information can be obtained from a stereo radiation camera, it is impossible to use a general stereo calibration algorithm directly. In this paper, we develop a hybrid-type stereo system which is equipped with both radiation and vision cameras. To calibrate the stereo radiation cameras, stereo images of a calibration pattern captured from the vision cameras are transformed in the view of the radiation cameras. The homography transformation is calibrated based on the geometric relationship between visual and radiation camera coordinates. The accuracy of the stereo parameters of the radiation camera is analyzed by distance measurements to both visual light and gamma sources. The experimental results show that the measurement error is about 3%.

  5. Formation of Hubbard-like bands as a fingerprint of strong electron-electron interactions in FeSe

    Science.gov (United States)

    Watson, Matthew D.; Backes, Steffen; Haghighirad, Amir A.; Hoesch, Moritz; Kim, Timur K.; Coldea, Amalia I.; Valentí, Roser

    2017-02-01

    We use angle-resolved photoemission spectroscopy (ARPES) to explore the electronic structure of single crystals of FeSe over a wide range of binding energies and study the effects of strong electron-electron correlations. We provide evidence for the existence of "Hubbard-like bands" at high binding energies consisting of incoherent many-body excitations originating from Fe 3 d states in addition to the renormalized quasiparticle bands near the Fermi level. Many high-energy features of the observed ARPES data can be accounted for when incorporating the effects of strong local Coulomb interactions in calculations of the spectral function via dynamical mean-field theory, including the formation of a Hubbard-like band. This shows that over the energy scale of several eV, local correlations arising from the on-site Coulomb repulsion and Hund's coupling are essential for a proper understanding of the electronic structure of FeSe and other related iron-based superconductors.

  6. Influence of variations in the electron-electron interaction on the ground state metric space "band structure" of a two-electron magnetic system

    Science.gov (United States)

    Sharp, P. M.; D'Amico, I.

    2016-02-01

    We consider a model system of two electrons confined in a two-dimensional harmonic oscillator potential, with the electrons interacting via an α / r2 potential, and subject to a magnetic field applied perpendicular to the plane of confinement. Our results show that variations in the strength of the electron-electron interaction generate a "band structure" in ground state metric spaces, which shares many characteristics with those generated as a result of varying the confinement potential. In particular, the metric spaces for wavefunctions, particle densities, and paramagnetic current densities all exhibit distinct "bands" and "gaps". The behavior of the polar angle of the bands also shares traits with that obtained by varying the confinement potential, but the behavior of the arc lengths of the bands on the metric space spheres can be seen to be different for the two cases and opposite for a large range of angular momentum values. The findings here and in Refs. [1,2] demonstrate that the "band structure" that arises in ground state metric spaces when a magnetic field is applied is a robust feature.

  7. Effect of Coulomb Interaction on Dynamical Localization in a Two-Electron Quantum-Dot Molecule

    Institute of Scientific and Technical Information of China (English)

    WANG Li-Min; DUAN Su-Qing; ZHAO Xian-Geng; LIU Cheng-Shi

    2004-01-01

    The combined interaction of Coulomb interaction and ac fields with two electrons in a quantum dot molecule is studied respectively with numerical simulation, perturbation theory and the approximation of driven two-level model. The dynamical localization occurs with the ac field whose ratio of the amplitude to the angular frequency is a root of n-order Bessel functions, where n is determined by the Coulomb interaction energy. Such results are explained with either the driven two-level approximation or the degenerated three-level model and verified by the numerical simulations.

  8. Constraints on exotic spin-dependent interactions between electrons from helium fine-structure spectroscopy

    Science.gov (United States)

    Ficek, Filip; Kimball, Derek F. Jackson; Kozlov, Mikhail G.; Leefer, Nathan; Pustelny, Szymon; Budker, Dmitry

    2017-03-01

    Agreement between theoretical calculations of atomic structure and spectroscopic measurements is used to constrain possible contribution of exotic spin-dependent interactions between electrons to the energy differences between states in helium-4. In particular, constraints on dipole-dipole interactions associated with the exchange of pseudoscalar bosons (such as axions or axion-like particles) with masses 10-2≲m ≲104eV are improved by a factor of ˜100 . The first atomic-scale constraints on several exotic velocity-dependent dipole-dipole interactions are established as well.

  9. Constraints on exotic spin-dependent interactions between electrons from helium fine-structure spectroscopy

    CERN Document Server

    Ficek, Filip; Kozlov, Mikhail; Leefer, Nathan; Pustelny, Szymon; Budker, Dmitry

    2016-01-01

    Agreement between theoretical calculations of atomic structure and spectroscopic measurements is used to constrain possible contribution of exotic spin-dependent interactions between electrons to the energy differences between states in helium-4. In particular, constraints on dipole-dipole interactions associated with the exchange of pseudoscalar bosons (such as axions or axion-like particles, ALPs) with masses $10^{-2}~{\\rm eV} \\lesssim m \\lesssim 10^{4}~{\\rm eV}$ are improved by a factor of $\\sim 100$. The first atomic-scale constraints on several exotic velocity-dependent dipole-dipole interactions are established as well.

  10. Electron emission induced by resonant coherent interaction in ion-surface scattering at grazing incidence

    Energy Technology Data Exchange (ETDEWEB)

    Garcia de Abajo, F.J. (Departamento de Ciencias de la Computacion e Inteligencia Artificial, Facultad de Informatica, Universidad del Pais Vasco, Apartado 649, 20080 San Sebastian (Spain)); Ponce, V.H.; Echenique, P.M. (Departamento de Fisica de Materiales, Facultad de Quimica, Universidad del Pais Vasco, Apartado 1072, 20080 San Sebastian (Spain))

    1994-01-15

    The resonant coherent interaction of an ion with an oriented crystal surface, under grazing-incidence conditions with respect to a special direction of the crystal, gives rise to electron loss to the continuum from electronic bound states of the ion. The calculations presented below predict large probabilities for electron emission due to this mechanism. The electrons are emitted with well defined energies, expressed in terms of the condition of resonance. Furthermore, the emission takes place around certain preferential directions, which are determined by both the latter condition and the symmetry of the surface lattice. Our calculations for MeV He[sup +] ions scattered at a W(001) surface along the [l angle]100[r angle] direction with glancing angle of 0--2 mrad indicate a yield of emission close to 1. Using heavier projectiles, one obtains smaller yields, but still large enough to be measurable in some cases (e.g., [approx]0.9 for 53 MeV B[sup 4+] and an angle of incidence of 1 mrad). Besides, the initial bound state is energy shifted due to the interaction with both the crystal potential and the velocity-dependent image potential. This results in a slight shift of the peaks of emission, which suggests a possible spectroscopy for analyzing the dynamical interaction of electronic bound states with solid surfaces.

  11. Dependence of Xmax and multiplicity of electron and muon on different high energy interaction models

    Directory of Open Access Journals (Sweden)

    G Rastegarzadeh

    2010-06-01

    Full Text Available Different high energy interaction models are the applied in CORSIKA code to simulate Extensive Air Showers (EAS generated by Cosmic Rays (CR. In this work the effects of QGSJET01, QGSJETII, DPMJET, SIBYLL models on Xmax and multiplicity of secondary electrons and muons at observation level are studied.

  12. Electron-phonon interaction in a semiconductor quantum wire embedded into the semiconductor medium

    CERN Document Server

    Zharkoj, V P

    2002-01-01

    The renormalization of electron ground state energy due to the different types of interaction with confined (L) and interface (I) phonons in a semiconductor cylindrical quantum wire (QW) embedded into the semiconductor medium by the example of a HgS/CdS nanosystem.

  13. A Case Study: Implementing an Interactive Video Instruction System in Teaching Electronics and Industrial Maintenance.

    Science.gov (United States)

    Shipe, Ron; And Others

    A study examined the development and implementation of an interactive video instruction system for teaching electronics and industrial maintenance at the University of Tennessee. The specific purposes of the study were to document unusual problems that may be encountered when this new technology is implemented, suggest corrective actions, and…

  14. Three-wave interaction during electron cyclotron resonance heating and current drive

    DEFF Research Database (Denmark)

    Nielsen, Stefan Kragh; Jacobsen, Asger Schou; Hansen, Søren Kjer

    2016-01-01

    Non-linear wave-wave interactions in fusion plasmas, such as the parametric decay instability (PDI) of gyrotron radiation, can potentially hamper the use of microwave diagnostics. Here we report on anomalous scattering in the ASDEX Upgrade tokamak during electron cyclotron resonance heating...

  15. Towards hot electron mediated charge exchange in hyperthermal energy ion-surface interactions

    DEFF Research Database (Denmark)

    Ray, M. P.; Lake, R. E.; Thomsen, Lasse Bjørchmar;

    2010-01-01

    electrons useful for driving chemical reactions at surfaces. Using the binary collision approximation and a nonadiabatic model that takes into account the time-varying nature of the ion–surface interaction, the energy loss of the ions is reproduced. The energy loss for Na + ions incident on the devices...

  16. Phonon interaction of electron in the translation-invariant strong-coupling theory

    OpenAIRE

    Lakhno, Victor D.

    2015-01-01

    A dependence of phonon interaction on the interelectronic distance is found for a translation-invariant (TI) strong-coupling bipolaron. It is shown that the charge induced by the electrons in a TI-bipolaron state is always greater than that in a bipolaron with spontaneously broken symmetry.

  17. Interaction effects on galaxy pairs with Gemini/GMOS- I: Electron density

    CERN Document Server

    Krabbe, A C; Dors, O L; Pastoriza, M G; Winge, C; Hagele, G F; Cardaci, M V; Rodrigues, I

    2013-01-01

    We present an observational study about the impacts of the interactions in the electron density of \\ion{H}{ii} regions located in 7 systems of interacting galaxies. The data consist of long-slit spectra in the range 4400-7300 A, obtained with the Gemini Multi-Object Spectrograph at Gemini South (GMOS). The electron density was determined using the ratio of emission lines [SII]6716/6731. Our results indicate that the electron density estimates obtained of HII regions from our sample of interacting galaxies are systematically higher than those derived for isolated galaxies. The mean electron density values of interacting galaxies are in the range of $N_{\\rm e}=24-532$\\,$ \\rm cm^{-3}$, while those obtained for isolated galaxies are in the range of $N_{\\rm e}=40-137\\: \\rm cm^{-3}$. Comparing the observed emission lines with predictions of photoionization models, we verified that almost all the \\ion{H}{ii} regions of the galaxies AM\\,1054A, AM\\,2058B, and AM\\,2306B, have emission lines excited by shock gas. For th...

  18. A new mechanism for high-[Tc]: Electron scattering from interacting tunneling units

    Energy Technology Data Exchange (ETDEWEB)

    Klein, M.W.; Simanovsky, S.B. (Worcester Polytechnic Inst., MA (United States). Dept. of Physics)

    1998-12-20

    A theoretical model for high-[Tc] superconductivity is presented based on electron pairing due to their interaction with two-level or multi-level tunneling units (TU's) present in high-[Tc] materials. TU's were found experimentally in YBa[sub 2]Cu[sub 3]O[sub 7[minus][delta

  19. From phase separation to long-range order in a system of interacting electrons

    Science.gov (United States)

    Derzhko, Volodymyr; Jȩdrzejewski, Janusz

    2003-10-01

    We study a system composed of fermions (electrons), hopping on a square lattice, and of immobile particles (ions), that is described by the spinless Falicov-Kimball Hamiltonian augmented by a next-nearest-neighbor attractive interaction between the ions (a nearest-neighbor repulsive interaction between the ions can be included and does not alter the results). A part of the grand-canonical phase diagram of this system is constructed rigorously, when the coupling between the electrons and ions is much stronger than the hopping intensity of electrons. The obtained diagram implies that, at least for a few rational densities of particles, by increasing the hopping intensity the system can be driven from a state of phase separation to a state with a long-range order. This kind of transitions occurs also, when the hopping fermions are replaced by hopping hard-core bosons.

  20. Quantum radiation reaction in head-on laser-electron beam interaction

    CERN Document Server

    Vranic, Marija; Fonseca, Ricardo A; Silva, Luis O

    2015-01-01

    In this paper, we investigate the evolution of the energy spread and the divergence of electron beams while they interact with different laser pulses at intensities where quantum effects and radiation reaction are of relevance. The interaction is modeled with a QED-PIC code and the results are compared with those obtained with a standard PIC code with the addition of a classical radiation reaction module and with theoretical predictions. While classical radiation reaction is a continuous process, in QED, radiation emission is stochastic. The two pictures reconcile in the limit when the emitted photons energy is small compared to the energy of the emitting electrons. The energy spread of the electron distribution function always tends to decrease with classical radiation reaction, whereas the stochastic QED emission can also enlarge it. These two tendencies compete in the QED-dominated regime. Our analysis, supported by the QED module, reveals an upper limit to the maximal attainable energy spread due to stoch...

  1. Soft Electronics Enabled Ergonomic Human-Computer Interaction for Swallowing Training

    Science.gov (United States)

    Lee, Yongkuk; Nicholls, Benjamin; Sup Lee, Dong; Chen, Yanfei; Chun, Youngjae; Siang Ang, Chee; Yeo, Woon-Hong

    2017-04-01

    We introduce a skin-friendly electronic system that enables human-computer interaction (HCI) for swallowing training in dysphagia rehabilitation. For an ergonomic HCI, we utilize a soft, highly compliant (“skin-like”) electrode, which addresses critical issues of an existing rigid and planar electrode combined with a problematic conductive electrolyte and adhesive pad. The skin-like electrode offers a highly conformal, user-comfortable interaction with the skin for long-term wearable, high-fidelity recording of swallowing electromyograms on the chin. Mechanics modeling and experimental quantification captures the ultra-elastic mechanical characteristics of an open mesh microstructured sensor, conjugated with an elastomeric membrane. Systematic in vivo studies investigate the functionality of the soft electronics for HCI-enabled swallowing training, which includes the application of a biofeedback system to detect swallowing behavior. The collection of results demonstrates clinical feasibility of the ergonomic electronics in HCI-driven rehabilitation for patients with swallowing disorders.

  2. Nonlinear interactions between electromagnetic waves and electron plasma oscillations in quantum plasmas.

    Science.gov (United States)

    Shukla, P K; Eliasson, B

    2007-08-31

    We consider nonlinear interactions between intense circularly polarized electromagnetic (CPEM) waves and electron plasma oscillations (EPOs) in a dense quantum plasma, taking into account the electron density response in the presence of the relativistic ponderomotive force and mass increase in the CPEM wave fields. The dynamics of the CPEM waves and EPOs is governed by the two coupled nonlinear Schrödinger equations and Poisson's equation. The nonlinear equations admit the modulational instability of an intense CPEM pump wave against EPOs, leading to the formation and trapping of localized CPEM wave pipes in the electron density hole that is associated with a positive potential distribution in our dense plasma. The relevance of our investigation to the next generation intense laser-solid density plasma interaction experiments is discussed.

  3. Energetic electron precipitation in weak to moderate corotating interaction region-driven storms

    Science.gov (United States)

    Ødegaard, Linn-Kristine Glesnes; Tyssøy, Hilde Nesse; Søraas, Finn; Stadsnes, Johan; Sandanger, Marit Irene

    2017-03-01

    High-energy electron precipitation from the radiation belts can penetrate deep into the mesosphere and increase the production rate of NOx and HOx, which in turn will reduce ozone in catalytic processes. The mechanisms for acceleration and loss of electrons in the radiation belts are not fully understood, and most of the measurements of the precipitating flux into the atmosphere have been insufficient for estimating the loss cone flux. In the present study the electron flux measured by the NOAA POES Medium Energy Proton and Electron Detectors 0° and 90° detectors is combined together with theory of pitch angle diffusion by wave-particle interaction to quantify the electron flux lost below 120 km altitude. Using this method, 41 weak and moderate geomagnetic storms caused by corotating interaction regions during 2006-2010 are studied. The dependence of the energetic electron precipitation fluxes upon solar wind parameters and geomagnetic indices is investigated. Nine storms give increased precipitation of >˜750 keV electrons. Nineteen storms increase the precipitation of >˜300 keV electrons, but not the >˜750 keV population. Thirteen storms either do not change or deplete the fluxes at those energies. Storms that have an increase in the flux of electrons with energy >˜300 keV are characterized by an elevated solar wind velocity for a longer period compared to the storms that do not. Storms with increased precipitation of >˜750 keV flux are distinguished by higher-energy input from the solar wind quantified by the ɛ parameter and corresponding higher geomagnetic activity.

  4. Exact and variational calculations of eigenmodes for three-dimensional free electron laser interaction with a warm electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Xie, M. [Lawrence Berkeley Lab., CA (United States)

    1995-12-31

    I present an exact calculation of free-electron-laser (FEL) eigenmodes (fundamental as well as higher order modes) in the exponential-gain regime. These eigenmodes specify transverse profiles and exponential growth rates of the laser field, and they are self-consistent solutions of the coupled Maxwell-Vlasov equations describing the FEL interaction taking into account the effects due to energy spread, emittance and betatron oscillations of the electron beam, and diffraction and guiding of the laser field. The unperturbed electron distribution is assumed to be of Gaussian shape in four dimensional transverse phase space and in the energy variable, but uniform in longitudinal coordinate. The focusing of the electron beam is assumed to be matched to the natural wiggler focusing in both transverse planes. With these assumptions the eigenvalue problem can be reduced to a numerically manageable integral equation and solved exactly with a kernel iteration method. An approximate, but more efficient solution of the integral equation is also obtained for the fundamental mode by a variational technique, which is shown to agree well with the exact results. Furthermore, I present a handy formula, obtained from interpolating the numerical results, for a quick calculation of FEL exponential growth rate. Comparisons with simulation code TDA will also be presented. Application of these solutions to the design and multi-dimensional parameter space optimization for an X-ray free electron laser driven by SLAC linac will be demonstrated. In addition, a rigorous analysis of transverse mode degeneracy and hence the transverse coherence of the X-ray FEL will be presented based on the exact solutions of the higher order guided modes.

  5. Solar Eclipse Video Captured by STEREO-B

    Science.gov (United States)

    2007-01-01

    No human has ever witnessed a solar eclipse quite like the one captured on this video. The NASA STEREO-B spacecraft, managed by the Goddard Space Center, was about a million miles from Earth , February 25, 2007, when it photographed the Moon passing in front of the sun. The resulting movie looks like it came from an alien solar system. The fantastically-colored star is our own sun as STEREO sees it in four wavelengths of extreme ultraviolet light. The black disk is the Moon. When we observe a lunar transit from Earth, the Moon appears to be the same size as the sun, a coincidence that produces intoxicatingly beautiful solar eclipses. The silhouette STEREO-B saw, on the other hand, was only a fraction of the Sun. The Moon seems small because of the STEREO-B location. The spacecraft circles the sun in an Earth-like orbit, but it lags behind Earth by one million miles. This means STEREO-B is 4.4 times further from the Moon than we are, and so the Moon looks 4.4 times smaller. This version of the STEREO-B eclipse movie is a composite of data from the coronagraph and extreme ultraviolet imager of the spacecraft. STEREO-B has a sister ship named STEREO-A. Both are on a mission to study the sun. While STEREO-B lags behind Earth, STEREO-A orbits one million miles ahead ('B' for behind, 'A' for ahead). The gap is deliberate as it allows the two spacecraft to capture offset views of the sun. Researchers can then combine the images to produce 3D stereo movies of solar storms. The two spacecraft were launched in Oct. 2006 and reached their stations on either side of Earth in January 2007.

  6. Theoretical Study of Ultra-Relativistic Laser Electron Interaction with Radiation Reaction by Quantum Description

    Science.gov (United States)

    Seto, Keita; Nagatomo, Hideo; Koga, James; Mima, Kunioki

    In the near future, the intensity of the ultra-short pulse laser will reach to 1022 W/cm2. When an electron is irradiated by this laser, the electron's behavior is relativistic with significant bremsstrahlung. This radiation from the electron is regarded as the energy loss of electron. Therefore, the electron's motion changes because of the kinetic energy changing. This radiation effect on the charged particle is the self-interaction, called the “radiation reaction” or the “radiation damping”. For this reason, the radiation reaction appears in laser electron interactions with an ultra-short pulse laser whose intensity becomes larger than 1022 W/cm2. In the classical theory, it is described by the Lorentz-Abraham-Dirac (LAD) equation. But, this equation has a mathematical difficulty, which we call the “run-away”. Therefore, there are many methods for avoiding this problem. However, Dirac's viewpoint is brilliant, based on the idea of quantum electrodynamics. We propose a new equation of motion in the quantum theory with radiation reaction in this paper.

  7. Light sea fermions in electron-proton and muon-proton interactions

    Science.gov (United States)

    Jentschura, U. D.

    2013-12-01

    The proton radius conundrum [Pohl et al., Nature 466, 213 (2010), 10.1038/nature09250 and Antognini et al., Science 339, 417 (2013), 10.1126/science.1230016] highlights the need to revisit any conceivable sources of electron-muon nonuniversality in lepton-proton interactions within the standard model. Superficially, a number of perturbative processes could appear to lead to such a nonuniversality. One of these is a coupling of the scattered electron into an electronic vacuum-polarization loop as opposed to a muonic one in the photon exchange of two valence quarks, which is present only for electron projectiles as opposed to muon projectiles. However, we show that this effect actually is part of the radiative correction to the proton's polarizability contribution to the Lamb shift, equivalent to a radiative correction to double scattering. We conclude that any conceivable genuine nonuniversality must be connected with a nonperturbative feature of the proton's structure, e.g., with the possible presence of light sea fermions as constituent components of the proton. If we assume an average of roughly 0.7×10-7 light sea positrons per valence quark, then we can show that virtual electron-positron annihilation processes lead to an extra term in the electron-proton versus muon-proton interaction, which has the right sign and magnitude to explain the proton radius discrepancy.

  8. Stereo morphology of temporal bone and ear

    Institute of Scientific and Technical Information of China (English)

    戴朴; 刘阳; 姜泗长; 方耀云; 王今; 杨伟炎

    2004-01-01

    Background The temporal bone has the most complicated anatomic feature among the whole human body, which always challenges otolaryngologists. This study was to study three-dimensional (3D) morphology of the temporal bone and the ear by means of a computer image processing technique, for the purpose of providing a 3D image to help in pathological, diagnostic and surgical procedures. Methods Forty sets of temporal bone celloidin serial sections with reference points were prepared and the contours of selected structures and reference points were entered into a graphics programme. The technique of computer-aided 3D reconstruction was applied to obtain 3D images and parameters of the temporal bones and the ears. Stereo views of the ossicles (n=5), the facial nerves (n=11), the posterior tympanic sinuses (n=11), the posterior ampullary nerves (n=4), the endolymphatic ducts and sacs (n=5), and the bony and membranous labyrinth (n=1) were reconstructed. Results Three-dimensional images, including the cochlea, the ossicles, the nerves, the tendons and the endolymphatic fluid system in the temporal bone, were obtained. Stereo picture pairs and 3D parameters of spatial dimensions, angle and volume for these reconstructed structures were calculated. The arrangement of the ossicles, spatial relationship of the bony and membranous labyrinth, the whole course of the facial nerves, the endolymphatic sac and posterior tympanic cavity were clearly observable. Stereo picture pairs made the spatial relationships among the above-mentioned structures much clearer. The operation of the posterior ampullary nerve transection was designed and simulated on the graphic computer based on 3D anatomic investigations. Conclusion The technique of computer-aided 3D reconstruction provides a new tool to observe the morphology of the temporal bone and thus may allow design and study of new surgical approaches.

  9. STEREO Superior Solar Conjunction Mission Phase

    Science.gov (United States)

    Ossing, Daniel A.; Wilson, Daniel; Balon, Kevin; Hunt, Jack; Dudley, Owen; Chiu, George; Coulter, Timothy; Reese, Angel; Cox, Matthew; Srinivasan, Dipak; hide

    2017-01-01

    With its long duration and high gain antenna (HGA) feed thermal constraint; the NASA Solar-TErestrial RElations Observatory (STEREO) solar conjunction mission phase is quite unique to deep space operations. Originally designed for a two year heliocentric orbit mission to primarily study coronal mass ejection propagation, after 8 years of continuous science data collection, the twin STEREO observatories entered the solar conjunction mission phase, for which they were not designed. Nine months before entering conjunction, an unforeseen thermal constraint threatened to stop daily communications and science data collection for 15months. With a 3.5 month long communication blackout from the superior solar conjunction, without ground commands, each observatory will reset every 3 days, resulting in 35 system resets at an Earth range of 2 AU. As the observatories will be conjoined for the first time in 8 years, a unique opportunity for calibrating the same instruments on identical spacecraft will occur. As each observatory has lost redundancy, and with only a limited fidelity hardware simulator, how can the new observatory configuration be adequately and safely tested on each spacecraft? Without ground commands, how would a 3-axis stabilized spacecraft safely manage the ever accumulating system momentum without using propellant for thrusters? Could science data still be collected for the duration of the solar conjunction mission phase? Would the observatories survive? In its second extended mission, operational resources were limited at best. This paper discusses the solutions to the STEREO superior solar conjunction operational challenges, science data impact, testing, mission operations, results, and lessons learned while implementing.

  10. Small Orbital Stereo Tracking Camera Technology Development

    Science.gov (United States)

    Bryan, Tom; MacLeod, Todd; Gagliano, Larry

    2016-01-01

    On-Orbit Small Debris Tracking and Characterization is a technical gap in the current National Space Situational Awareness necessary to safeguard orbital assets and crew. This poses a major risk of MOD damage to ISS and Exploration vehicles. In 2015 this technology was added to NASA's Office of Chief Technologist roadmap. For missions flying in or assembled in or staging from LEO, the physical threat to vehicle and crew is needed in order to properly design the proper level of MOD impact shielding and proper mission design restrictions. Need to verify debris flux and size population versus ground RADAR tracking. Use of ISS for In-Situ Orbital Debris Tracking development provides attitude, power, data and orbital access without a dedicated spacecraft or restricted operations on-board a host vehicle as a secondary payload. Sensor Applicable to in-situ measuring orbital debris in flux and population in other orbits or on other vehicles. Could enhance safety on and around ISS. Some technologies extensible to monitoring of extraterrestrial debris as well To help accomplish this, new technologies must be developed quickly. The Small Orbital Stereo Tracking Camera is one such up and coming technology. It consists of flying a pair of intensified megapixel telephoto cameras to evaluate Orbital Debris (OD) monitoring in proximity of International Space Station. It will demonstrate on-orbit optical tracking (in situ) of various sized objects versus ground RADAR tracking and small OD models. The cameras are based on Flight Proven Advanced Video Guidance Sensor pixel to spot algorithms (Orbital Express) and military targeting cameras. And by using twin cameras we can provide Stereo images for ranging & mission redundancy. When pointed into the orbital velocity vector (RAM), objects approaching or near the stereo camera set can be differentiated from the stars moving upward in background.

  11. Stereo soft x-ray microscopy and elemental mapping of hematite and clay suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Gleber, S.-C.; Thieme, J.; Chao, W.; Fischer, P.

    2008-09-01

    The spatial arrangements of hematite particles within aqueous soil and clay samples are investigated with soft X-ray microscopy, taking advantage of the elemental contrast at the Fe-L edge around E = 707 eV. In combination with stereo microscopy, information about spatial arrangements are revealed and correlated to electrostatic interactions of the different mixtures. Manipulation of a sample mounted to the microscope is possible and particles added while imaging can be detected.

  12. High Harmonic Inverse Free-Electron-Laser Interaction at 800 NM

    CERN Document Server

    Sears, Chris M S; Colby, Eric R; Cowan, Benjamin; Plettner, Tomas; Siemann, Robert; Spencer, James

    2005-01-01

    The inverse Free Electron Laser (IFEL) interaction has recently been proposed and used as a short wavelength modulator forμbunching of beams for laser acceleration experiments*,**. These experiments utilized the fundamental of the interaction between the laser field and electron bunch. In the current experiment, we explore the higher order resonances of the IFEL interaction from a 3 period, 1.8 centimeter wavelength undulator with a picosecond, 0.25 mJ/pulse laser at 800 nm. The resonances are observed by adjusting the gap of the undulator while keeping the beam energy constant. We will also discuss diagnostics for obtaining beam overlap and statistical techniques used to account for machine drifts and analyze the data.

  13. Developing stereo image based robot control system

    Science.gov (United States)

    Suprijadi, Pambudi, I. R.; Woran, M.; Naa, C. F.; Srigutomo, W.

    2015-04-01

    Application of image processing is developed in various field and purposes. In the last decade, image based system increase rapidly with the increasing of hardware and microprocessor performance. Many fields of science and technology were used this methods especially in medicine and instrumentation. New technique on stereovision to give a 3-dimension image or movie is very interesting, but not many applications in control system. Stereo image has pixel disparity information that is not existed in single image. In this research, we proposed a new method in wheel robot control system using stereovision. The result shows robot automatically moves based on stereovision captures.

  14. Hyperspectral photometric stereo for a single capture.

    Science.gov (United States)

    Ozawa, Keisuke; Sato, Imari; Yamaguchi, Masahiro

    2017-03-01

    We present a single-capture photometric stereo method using a hyperspectral camera. A spectrally and spatially designed illumination enables a point-wise estimation of reflectance spectra and surface normals from a single hyperspectral image. The illumination works as a reflectance probe in wide spectral regions where reflectance spectra are measured, and the full spectra are estimated by interpolation. It also works as the resource for shadings in other spectral regions. The accuracy of estimation is evaluated in a simulation. Also, we prepare an experimental setup and demonstrate a surface reconstruction against a real scene.

  15. A Stereo Vision Visualization Method in Welding

    Science.gov (United States)

    Zhao, Chuangxin; Richardson, Ian M.; Kleijn, Chris; Kenjeres, Sasa; Saldi, Zaki

    2008-09-01

    The oscillation of weld pool surface, vaporization and spatters make the measurement in welding difficult; two dimensional results can not reflect enough information in welding. However, there are few direct three dimensional methods to understand the fluid flow during welding. In this paper, we described a three dimensional reconstruction method to measure velocity in welding based on a single high speed camera. A stereo adapter was added in front of the high speed camera lens to obtain two images in the same frame from different view points at the same time; according to the machine vision theory, three dimensional parameters could be reconstructed based on these two images

  16. Developing stereo image based robot control system

    Energy Technology Data Exchange (ETDEWEB)

    Suprijadi,; Pambudi, I. R.; Woran, M.; Naa, C. F; Srigutomo, W. [Department of Physics, FMIPA, InstitutTeknologi Bandung Jl. Ganesha No. 10. Bandung 40132, Indonesia supri@fi.itb.ac.id (Indonesia)

    2015-04-16

    Application of image processing is developed in various field and purposes. In the last decade, image based system increase rapidly with the increasing of hardware and microprocessor performance. Many fields of science and technology were used this methods especially in medicine and instrumentation. New technique on stereovision to give a 3-dimension image or movie is very interesting, but not many applications in control system. Stereo image has pixel disparity information that is not existed in single image. In this research, we proposed a new method in wheel robot control system using stereovision. The result shows robot automatically moves based on stereovision captures.

  17. Electron acceleration at Jupiter: input from cyclotron-resonant interaction with whistler-mode chorus waves

    Directory of Open Access Journals (Sweden)

    E. E. Woodfield

    2013-10-01

    Full Text Available Jupiter has the most intense radiation belts of all the outer planets. It is not yet known how electrons can be accelerated to energies of 10 MeV or more. It has been suggested that cyclotron-resonant wave-particle interactions by chorus waves could accelerate electrons to a few MeV near the orbit of Io. Here we use the chorus wave intensities observed by the Galileo spacecraft to calculate the changes in electron flux as a result of pitch angle and energy diffusion. We show that, when the bandwidth of the waves and its variation with L are taken into account, pitch angle and energy diffusion due to chorus waves is a factor of 8 larger at L-shells greater than 10 than previously shown. We have used the latitudinal wave intensity profile from Galileo data to model the time evolution of the electron flux using the British Antarctic Survey Radiation Belt (BAS model. This profile confines intense chorus waves near the magnetic equator with a peak intensity at ∼5° latitude. Electron fluxes in the BAS model increase by an order of magnitude for energies around 3 MeV. Extending our results to L = 14 shows that cyclotron-resonant interactions with chorus waves are equally important for electron acceleration beyond L = 10. These results suggest that there is significant electron acceleration by cyclotron-resonant interactions at Jupiter contributing to the creation of Jupiter's radiation belts and also increasing the range of L-shells over which this mechanism should be considered.

  18. Deleterious epistatic interactions between electron transport system protein-coding loci in the copepod Tigriopus californicus.

    Science.gov (United States)

    Willett, Christopher S

    2006-07-01

    The nature of epistatic interactions between genes encoding interacting proteins in hybrid organisms can have important implications for the evolution of postzygotic reproductive isolation and speciation. At this point very little is known about the fitness differences caused by specific closely interacting but evolutionarily divergent proteins in hybrids between populations or species. The intertidal copepod Tigriopus californicus provides an excellent model in which to study such interactions because the species range includes numerous genetically divergent populations that are still capable of being crossed in the laboratory. Here, the effect on fitness due to the interactions of three complex III proteins of the electron transport system in F2 hybrid copepods resulting from crosses of a pair of divergent populations is examined. Significant deviations from Mendelian inheritance are observed for each of the three genes in F2 hybrid adults but not in nauplii (larvae). The two-way interactions between these genes also have a significant impact upon the viability of these hybrid copepods. Dominance appears to play an important role in mediating the interactions between these loci as deviations are caused by heterozygote/homozygote deleterious interactions. These results suggest that the fitness consequences of the interactions of these three complex III-associated genes could influence reproductive isolation in this system.

  19. Miniature photometric stereo system for textile surface structure reconstruction

    Science.gov (United States)

    Gorpas, Dimitris; Kampouris, Christos; Malassiotis, Sotiris

    2013-04-01

    In this work a miniature photometric stereo system is presented, targeting the three-dimensional structural reconstruction of various fabric types. This is a supportive module to a robot system, attempting to solve the well known "laundry problem". The miniature device has been designed for mounting onto the robot gripper. It is composed of a low-cost off-the-shelf camera, operating in macro mode, and eight light emitting diodes. The synchronization between image acquisition and lighting direction is controlled by an Arduino Nano board and software triggering. The ambient light has been addressed by a cylindrical enclosure. The direction of illumination is recovered by locating the reflection or the brightest point on a mirror sphere, while a flatfielding process compensates for the non-uniform illumination. For the evaluation of this prototype, the classical photometric stereo methodology has been used. The preliminary results on a large number of textiles are very promising for the successful integration of the miniature module to the robot system. The required interaction with the robot is implemented through the estimation of the Brenner's focus measure. This metric successfully assesses the focus quality with reduced time requirements in comparison to other well accepted focus metrics. Besides the targeting application, the small size of the developed system makes it a very promising candidate for applications with space restrictions, like the quality control in industrial production lines or object recognition based on structural information and in applications where easiness in operation and light-weight are required, like those in the Biomedical field, and especially in dermatology.

  20. Diffusion coefficients from resonant interactions with electrostatic electron cyclotron harmonic waves

    Science.gov (United States)

    Tripathi, A. K.; Singhal, R. P.

    2009-11-01

    Pitch-angle diffusion coefficients have been calculated for resonant interaction with electrostatic electron cyclotron harmonic (ECH) waves using quasilinear diffusion theory. Unlike previous calculations, the parallel group velocity has been included in this study. Further, ECH wave intensity is expressed as a function of wave frequency and wave normal angle with respect to ambient magnetic field. It is found that observed wave electric field amplitudes in Earth's magnetosphere are sufficient to set electrons on strong diffusion in the energy ranges of a few hundred eV. However, the required amplitudes are larger than the observed values for keV electrons and higher by about a factor of 3 compared to past calculations. Required electric field amplitudes are smaller at larger radial distances. It is concluded that ECH waves are responsible for diffuse auroral precipitation of electrons with energies less than about 500 eV.

  1. Extension of Pierce model to multiple transmission lines interacting with an electron beam

    CERN Document Server

    Tamma, Venkata Ananth

    2013-01-01

    A possible route towards achieving high power microwave devices is through the use of novel slow-wave structures employing multiple coupled transmission lines (MTLs) whose behavior when coupled to electron beams have not been sufficiently explored. We present the extension of the one-dimensional linearized Pierce theory to MTLs coupled to a single electron beam. We develop multiple formalisms to calculate the k-{\\omega} dispersion relation of the system and find that the existence of a growing wave solution is always guaranteed if the electron propagation constant is larger than or equal to the largest propagation constant of the MTL system. We verify our findings with illustrative examples which bring to light unique properties of the system in which growing waves were found to exist within finite bands of the electron propagation constant and discuss possible approach to improve the gain. By treating the beam-MTL interaction as distributed dependent current generators in the MTL, we derive relations charact...

  2. The effect of quantum correction on plasma electron heating in ultraviolet laser interaction

    Science.gov (United States)

    Zare, S.; Yazdani, E.; Sadighi-Bonabi, R.; Anvari, A.; Hora, H.

    2015-04-01

    The interaction of the sub-picosecond UV laser in sub-relativistic intensities with deuterium is investigated. At high plasma temperatures, based on the quantum correction in the collision frequency, the electron heating and the ion block generation in plasma are studied. It is found that due to the quantum correction, the electron heating increases considerably and the electron temperature uniformly reaches up to the maximum value of 4.91 × 107 K. Considering the quantum correction, the electron temperature at the laser initial coupling stage is improved more than 66.55% of the amount achieved in the classical model. As a consequence, by the modified collision frequency, the ion block is accelerated quicker with higher maximum velocity in comparison with the one by the classical collision frequency. This study proves the necessity of considering a quantum mechanical correction in the collision frequency at high plasma temperatures.

  3. The effect of quantum correction on plasma electron heating in ultraviolet laser interaction

    Energy Technology Data Exchange (ETDEWEB)

    Zare, S.; Sadighi-Bonabi, R., E-mail: Sadighi@sharif.ir; Anvari, A. [Department of Physics, Sharif University of Technology, P.O. Box 11365-9567, Tehran (Iran, Islamic Republic of); Yazdani, E. [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Hora, H. [Department of Theoretical Physics, University of New South Wales, Sydney 2052 (Australia)

    2015-04-14

    The interaction of the sub-picosecond UV laser in sub-relativistic intensities with deuterium is investigated. At high plasma temperatures, based on the quantum correction in the collision frequency, the electron heating and the ion block generation in plasma are studied. It is found that due to the quantum correction, the electron heating increases considerably and the electron temperature uniformly reaches up to the maximum value of 4.91 × 10{sup 7 }K. Considering the quantum correction, the electron temperature at the laser initial coupling stage is improved more than 66.55% of the amount achieved in the classical model. As a consequence, by the modified collision frequency, the ion block is accelerated quicker with higher maximum velocity in comparison with the one by the classical collision frequency. This study proves the necessity of considering a quantum mechanical correction in the collision frequency at high plasma temperatures.

  4. Electron Fluid Description of Wave-Particle Interactions in Strong Buneman Turbulence

    CERN Document Server

    Che, H

    2014-01-01

    To understand the nature of anomalous resistivity in magnetic reconnection, we investigate turbulence-induced momentum transport and energy dissipation during Buneman instability in force-free current sheets. Using 3D particle-in-cell simulations, we find that the macroscopic effects generated by wave-particle interactions in Buneman instability can be approximately described by a set of electron fluid equations. These equations show that the energy dissipation and momentum transports along current sheets are locally quasi-static but globally non-static and irreversible. Turbulence drag dissipates both the streaming energy of current sheets and the associated magnetic energy. The decrease of magnetic field maintains an inductive electric field that re-accelerates electrons. The net loss of streaming energy is converted into the heat of electrons moving along the magnetic field and increases the electron Boltzmann entropy. The growth of self-sustained Buneman waves satisfies a Bernoulli-like equation that rela...

  5. Neutrinoless double positron decay and positron emitting electron capture in the interacting boson model

    CERN Document Server

    Barea, J; Iachello, F

    2015-01-01

    Neutrinoless double-$\\beta$ decay is of fundamental importance for determining the neutrino mass. Although double electron ($\\beta^-\\beta^-$) decay is the most promising mode, in very recent years interest in double positron ($\\beta^+\\beta^+$) decay, positron emitting electron capture ($EC\\beta^+$), and double electron capture ($ECEC$) has been renewed. We present here results of a calculation of nuclear matrix elements for neutrinoless double-$\\beta^+$ decay and positron emitting electron capture within the framework of the microscopic interacting boson model (IBM-2) for $^{58}$Ni, $^{64}$Zn, $^{78}$Kr, $^{96}$Ru, $^{106}$Cd, $^{124}$Xe, $^{130}$Ba, and $^{136}$Ce decay. By combining these with a calculation of phase space factors we calculate expected half-lives.

  6. Electron acceleration mechanisms in the interaction of ultrashort lasers with underdense plasmas: Experiments and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Faure, J.; Lefebvre, E.; Malka, V.; Marques, J.-R.; Amiranoff, F.; Solodov, A.; Mora, P.

    2002-06-30

    An experiment investigating the production of relativistic electrons from the interaction of ultrashort multi-terawatt laser pulses with an underdense plasma is presented. Electrons were accelerated to tens of MeV and the maximum electron energy increased as the plasma density decreased. Simulations have been performed in order to model the experiment. They show a good agreement with the trends observed in the experiment and the spectra of accelerated electrons could be reproduced successfully. The simulations have been used to study the relative contribution of the different acceleration mechanisms: plasma wave acceleration, direct laser acceleration and stochastic heating. The results show that in low density case (1 percent of the critical density) acceleration by laser is dominant mechanism. The simulations at high density also suggest that direct laser acceleration is more efficient that stochastic heating.

  7. Electronic inhomogeneities in graphene: the role of the substrate interaction and chemical doping

    Directory of Open Access Journals (Sweden)

    G. Rubio-Bollinger

    2012-09-01

    Full Text Available We probe the local inhomogeneities of the electronicproperties of graphene at the nanoscale usingscanning probe microscopy techniques. First, wefocus on the study of the electronic inhomogeneitiescaused by the graphene-substrate interaction ingraphene samples exfoliated on silicon oxide. Wefind that charged impurities, present in the graphenesubstrateinterface, perturb the carrier densitysignificantly and alter the electronic properties ofgraphene. This finding helps to understand theobserved device-to-device variation typically observedin graphene-based electronic devices. Second, weprobe the effect of chemical modification in theelectronic properties of graphene, grown by chemicalvapour deposition on nickel. We find that both thechemisorption of hydrogen and the physisorption ofporphyrin molecules strongly depress theconductance at low bias indicating the opening of abandgap in graphene, paving the way towards thechemical engineering of the electronic properties ofgraphene.

  8. Effects of the electron-electron interaction on electronic transport through the antibonding orbital of a longitudinally embedded double quantum dot

    Science.gov (United States)

    Aguiar-Hualde, J. M.; Chiappe, G.; Louis, E.

    2007-08-01

    The effects of the on-site electron-electron (e-e) interaction U on the electronic transport across two longitudinally embedded quantum dots in the regime in which the antibonding (AB) state of the isolated composite system is aligned with the Fermi level at the leads are investigated. This regime occurs when the dot orbital energy γd is negative and equal in magnitude to the hopping probability between the orbitals on the two dots. In the noninteracting case, the conductance approaches asymptotically the conductance quantum G0=2e2/h as γd decreases; in addition, the contribution of the AB channel to the conductance tends to 1. As shown here, this picture is substantially modified by the e-e interaction. For finite U , the conductance versus γd shows a maximum at which the value G0 is reached, being supported in this case by the two channels (bonding and antibonding); the relative weight of each channel depends on the actual value of the e-e interaction. In the limit γd=-∞ , the conductance is supported only by the AB channel (as in the noninteracting case), but it is always smaller than G0 . While the mechanism underlying these results is mainly one body for small U , the Kondo effect and quantum interference come into play at large U . The effects of the e-e interaction increase significantly as the leads-dots coupling decreases, in particular, the range over which the conductance is non-negligible is significantly narrowed. The possible implications on a physically related system, a hydrogen molecule longitudinally bridging two Pt electrodes, are discussed.

  9. Obstacle detection during day and night conditions using stereo vision

    NARCIS (Netherlands)

    Dubbelman, G.; Mark, W. van der; Heuvel, J.C. van den; Groen, F.C.A.

    2007-01-01

    We have developed a stereo vision based obstacle detection (OD) system that can be used to detect obstacles in off-road terrain during both day and night conditions. In order to acquire enough depth estimates for reliable OD during low visibility conditions, we propose a stereo disparity (depth) est

  10. A new benchmark for stereo-based pedestrian detection

    NARCIS (Netherlands)

    C.G. Keller; M. Enzweiler; D.M. Gavrila

    2011-01-01

    Pedestrian detection is a rapidly evolving area in the intelligent vehicles domain. Stereo vision is an attractive sensor for this purpose. But unlike for monocular vision, there are no realistic, large scale benchmarks available for stereo-based pedestrian detection, to provide a common point of re

  11. Object recognition with stereo vision and geometric hashing

    NARCIS (Netherlands)

    Dijck, van Harry; Heijden, van der Ferdinand

    2003-01-01

    In this paper we demonstrate a method to recognize 3D objects and to estimate their pose. For that purpose we use a combination of stereo vision and geometric hashing. Stereo vision is used to generate a large number of 3D low level features, of which many are spurious because at that stage of the p

  12. Object recognition with stereo vision and geometric hashing

    NARCIS (Netherlands)

    van Dijck, H.A.L.; van der Heijden, Ferdinand

    In this paper we demonstrate a method to recognize 3D objects and to estimate their pose. For that purpose we use a combination of stereo vision and geometric hashing. Stereo vision is used to generate a large number of 3D low level features, of which many are spurious because at that stage of the

  13. Owls see in stereo much like humans do

    NARCIS (Netherlands)

    Willigen, R.F. van der

    2011-01-01

    While 3D experiences through binocular disparity sensitivity have acquired special status in the understanding of human stereo vision, much remains to be learned about how binocularity is put to use in animals. The owl provides an exceptional model to study stereo vision as it displays one of the hi

  14. Diffuse auroral precipitation by resonant interaction with electron cyclotron harmonic and whistler mode waves

    Science.gov (United States)

    Tripathi, A. K.; Singhal, R. P.; Singh, K. P.; Singh, O. N.

    2013-05-01

    Bounce-averaged pitch angle diffusion coefficients of electrons due to resonant interaction with electrostatic electron cyclotron harmonic (ECH) and whistler mode waves have been calculated. Temporal growth rates obtained by solving the appropriate dispersion relation have been used to represent the distribution of wave energy with frequency. Calculations have been performed at two spatial locations L=4.6 and L=6.8. The results obtained suggest that ECH waves can put electrons on strong pitch angle diffusion at both spatial locations. However, at L=4.6, electrons with energy <100 eV and at L=6.8 electrons with energy up to ∼500 eV can be put on strong diffusion contributing to diffuse auroral precipitation. Whistler mode waves can put electrons of energy ≤5 keV on strong pitch angle diffusion at L=6.8 whereas at L=4.6 observed wave fields are insufficient to put electrons on strong diffusion. ECH waves contribute up to 17% of the total electron energy precipitation flux due to both ECH and whistler mode waves. A case study has been performed to calculate pitch angle diffusion coefficients using Gaussian function to represent wave energy distribution with frequency. It is found that, for electron energy <500 eV, the calculated diffusion coefficients using Gaussian function to represent ECH wave energy distribution are several orders of magnitude smaller or negligible as compared to diffusion coefficients calculated by temporal growth rates. However, the calculated pitch angle diffusion coefficients using Gaussian function for whistler mode wave energy distribution are in very good agreement with diffusion coefficients calculated by temporal growth rates. It is concluded that representing the ECH wave energy distribution with frequency by a Gaussian function grossly underestimates the low energy (<500 eV) electron precipitation flux due to ECH waves.

  15. Quantum ballistic transport by interacting two-electron states in quasi-one-dimensional channels

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Danhong [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Gumbs, Godfrey [Center for High Technology Materials, University of New Mexico, 1313 Goddard St SE, Albuquerque, New Mexico 87106 (United States); Abranyos, Yonatan [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Pepper, Michael; Kumar, Sanjeev [Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE (United Kingdom); London Centre for Nanotechnology, 17-19 Gordon Street, London, WC1H 0AH (United Kingdom)

    2015-11-15

    For quantum ballistic transport of electrons through a short conduction channel, the role of Coulomb interaction may significantly modify the energy levels of two-electron states at low temperatures as the channel becomes wide. In this regime, the Coulomb effect on the two-electron states is calculated and found to lead to four split energy levels, including two anticrossing-level and two crossing-level states. Moreover, due to the interplay of anticrossing and crossing effects, our calculations reveal that the ground two-electron state will switch from one anticrossing state (strong confinement) to a crossing state (intermediate confinement) as the channel width gradually increases and then back to the original anticrossing state (weak confinement) as the channel width becomes larger than a threshold value. This switching behavior leaves a footprint in the ballistic conductance as well as in the diffusion thermoelectric power of electrons. Such a switching is related to the triple spin degeneracy as well as to the Coulomb repulsion in the central region of the channel, which separates two electrons away and pushes them to different channel edges. The conductance reoccurrence region expands from the weak to the intermediate confinement regime with increasing electron density.

  16. Interaction between Solid Nitrogen and 1-3-keV Electrons

    DEFF Research Database (Denmark)

    Schou, Jørgen; Sørensen, H.

    1978-01-01

    Experimental studies were made of the interaction between solid nitrogen and beams of 1-2-keV electrons. The projected range for the electrons was measured by means of the mirror-substrate method (gold substrate), giving the result 9.02×1016 E1.75 molecules/cm2 with the energy given in ke......V. At 3 keV, the SEE coefficient is 12 times that for solid deuterium. This is attributed partly to the larger production rate for low-energy electrons in nitrogen and partly to the larger escape probability for these electrons. Moreover, measurements were made of the electron-reflection coefficient, both......V. The escape depth for secondary electrons was studied by means of the equivalent-substrate method (carbon substrate). The results varied from 280 Å at 1 keV to 400 Å at 3 keV. Measurements were also made of the secondary-electron-emission coefficient, which varied from 2.3 el/el at 1 keV to 1.2 el/el at 3 ke...

  17. Plasma-Wall Interaction and Electron Temperature Saturation in Hall Thrusters

    Science.gov (United States)

    Smirnov, Artem

    2005-10-01

    Existing Hall thruster models predict that secondary electron emission from the channel walls is significant and that the near-wall sheaths are space charge saturated. The plasma-wall interaction and its dependence on the discharge voltage and channel width were studied through the measurements of the electron temperature, plasma potential, and plasma density in a 2 kW Hall thruster [1,2]. The experimental electron-wall collision frequency is computed using the measured plasma parameters. For high discharge voltages, the deduced electron-wall collision frequency is much lower than the theoretical value obtained for the space charge saturated sheath regime, but larger than the wall recombination frequency. The observed electron temperature saturation appears to be directly associated with a decrease of the Joule heating, rather than with the enhancement of the electron energy loss at the walls due to a strong secondary electron emission. The channel width is shown to have a more significant effect on the axial distribution of the plasma potential than the discharge voltage. 1. Y. Raitses, D. Staack, M. Keidar, and N.J. Fisch, Phys. Plasmas 12, 057104 (2005). 2. Y. Raitses, D. Staack, A. Smirnov, and N.J. Fisch, Phys. Plasmas 12, 073507 (2005).

  18. Interaction between Solid Nitrogen and 1-3-keV Electrons

    DEFF Research Database (Denmark)

    Schou, Jørgen; Sørensen, H.

    1978-01-01

    Experimental studies were made of the interaction between solid nitrogen and beams of 1-2-keV electrons. The projected range for the electrons was measured by means of the mirror-substrate method (gold substrate), giving the result 9.02×1016 E1.75 molecules/cm2 with the energy given in ke......V. The escape depth for secondary electrons was studied by means of the equivalent-substrate method (carbon substrate). The results varied from 280 Å at 1 keV to 400 Å at 3 keV. Measurements were also made of the secondary-electron-emission coefficient, which varied from 2.3 el/el at 1 keV to 1.2 el/el at 3 ke......V. At 3 keV, the SEE coefficient is 12 times that for solid deuterium. This is attributed partly to the larger production rate for low-energy electrons in nitrogen and partly to the larger escape probability for these electrons. Moreover, measurements were made of the electron-reflection coefficient, both...

  19. Charge transfer dynamics from adsorbates to surfaces with single active electron and configuration interaction based approaches

    Energy Technology Data Exchange (ETDEWEB)

    Ramakrishnan, Raghunathan, E-mail: r.ramakrishnan@unibas.ch [Institute of Physical Chemistry, National Center for Computational Design and Discovery of Novel Materials (MARVEL), Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Nest, Mathias [Theoretische Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching (Germany)

    2015-01-13

    Highlights: • We model electron dynamics across cyano alkanethiolates attached to gold cluster. • We present electron transfer time scales from TD-DFT and TD-CI based simulations. • Both DFT and CI methods qualitatively predict the trend in time scales. • TD-CI predicts the experimental relative time scale very accurately. - Abstract: We employ wavepacket simulations based on many-body time-dependent configuration interaction (TD-CI), and single active electron theories, to predict the ultrafast molecule/metal electron transfer time scales, in cyano alkanethiolates bonded to model gold clusters. The initial states represent two excited states where a valence electron is promoted to one of the two virtual π{sup ∗} molecular orbitals localized on the cyanide fragment. The ratio of the two time scales indicate the efficiency of one charge transfer channel over the other. In both our one-and many-electron simulations, this ratio agree qualitatively with each other as well as with the previously reported experimental time scales (Blobner et al., 2012), measured for a macroscopic metal surface. We study the effect of cluster size and the description of electron correlation on the charge transfer process.

  20. Interaction-driven distinctive electronic states of artificial atoms at the ZnO interface

    Science.gov (United States)

    Chakraborty, Tapash; Manaselyan, Aram; Barseghyan, Manuk

    2017-06-01

    We have investigated the electronic states of planar quantum dots at the ZnO interface containing a few interacting electrons in an externally applied magnetic field. The electron-electron interaction effects are expected to be much stronger in this case than in traditional semiconductor quantum systems, such as in GaAs or InAs quantum dots. In order to highlight that stronger Coulomb effects in the ZnO quantum dots, we have compared the energy spectra and the magnetization in this system to those of the InAs quantum dots. We have found that in the ZnO quantum dots the signatures of stronger Coulomb interaction manifests in an unique ground state that has very different properties than the corresponding ones in the InAs dot. Our results for the magnetization also exhibits behaviors never before observed in a quantum dot for a realistic set of parameters. We have found a stronger temperature dependence and other unexpected features, such as paramagnetic-like behavior at high temperatures for a quantum-dot helium.

  1. Universal Quantum Criticality in the Metal-Insulator Transition of Two-Dimensional Interacting Dirac Electrons

    Science.gov (United States)

    Otsuka, Yuichi; Yunoki, Seiji; Sorella, Sandro

    2016-01-01

    The metal-insulator transition has been a subject of intense research since Mott first proposed that the metallic behavior of interacting electrons could turn to an insulating one as electron correlations increase. Here, we consider electrons with massless Dirac-like dispersion in two spatial dimensions, described by the Hubbard models on two geometrically different lattices, and perform numerically exact calculations on unprecedentedly large systems that, combined with a careful finite-size scaling analysis, allow us to explore the quantum critical behavior in the vicinity of the interaction-driven metal-insulator transition. Thereby, we find that the transition is continuous, and we determine the quantum criticality for the corresponding universality class, which is described in the continuous limit by the Gross-Neveu model, a model extensively studied in quantum field theory. Furthermore, we discuss a fluctuation-driven scenario for the metal-insulator transition in the interacting Dirac electrons: The metal-insulator transition is triggered only by the vanishing of the quasiparticle weight, not by the Dirac Fermi velocity, which instead remains finite near the transition. This important feature cannot be captured by a simple mean-field or Gutzwiller-type approximate picture but is rather consistent with the low-energy behavior of the Gross-Neveu model.

  2. Universal Quantum Criticality in the Metal-Insulator Transition of Two-Dimensional Interacting Dirac Electrons

    Directory of Open Access Journals (Sweden)

    Yuichi Otsuka

    2016-03-01

    Full Text Available The metal-insulator transition has been a subject of intense research since Mott first proposed that the metallic behavior of interacting electrons could turn to an insulating one as electron correlations increase. Here, we consider electrons with massless Dirac-like dispersion in two spatial dimensions, described by the Hubbard models on two geometrically different lattices, and perform numerically exact calculations on unprecedentedly large systems that, combined with a careful finite-size scaling analysis, allow us to explore the quantum critical behavior in the vicinity of the interaction-driven metal-insulator transition. Thereby, we find that the transition is continuous, and we determine the quantum criticality for the corresponding universality class, which is described in the continuous limit by the Gross-Neveu model, a model extensively studied in quantum field theory. Furthermore, we discuss a fluctuation-driven scenario for the metal-insulator transition in the interacting Dirac electrons: The metal-insulator transition is triggered only by the vanishing of the quasiparticle weight, not by the Dirac Fermi velocity, which instead remains finite near the transition. This important feature cannot be captured by a simple mean-field or Gutzwiller-type approximate picture but is rather consistent with the low-energy behavior of the Gross-Neveu model.

  3. One-Dimensional Physics of Interacting Electrons and Phonons in Carbon Nanotubes

    Science.gov (United States)

    Deshpande, Vikram Vijay

    The one-dimensional (1D) world is quite different from its higher dimensional counterparts. For example, the electronic ground state in 1D is not a Fermi liquid as in most solids, due to the role of electron-electron interactions. Most commonly, electrons in 1D are described as a Luttinger liquid , where the low-energy excitations are decoupled bosonic charge and spin waves. Carbon nanotubes are clean 1D systems which have been shown to behave like a Luttinger liquid at high electron density. However, at low electron density and in the absence of disorder, the ground state is predicted to be a 1D Wigner crystal---an electron solid dominated by long-range Coulomb interaction. Moreover, short-range interaction mediated by the atomic lattice (umklapp scattering) is predicted to transform a nominal 1D metal into a Mott insulator. In this thesis, we develop techniques to make extremely clean nanotube single-electron transistors. We study them in the few-electron/hole regime using Coulomb blockade spectroscopy in a magnetic field. In semiconducting nanotubes, we map out the antiferromagnetic exchange coupling as a function of carrier number and find excellent agreement to a Wigner crystal model. In nominally metallic nanotubes, we observe a universal energy gap in addition to the single-particle bandgap, implying that nanotubes are never metallic. The magnitude, radius dependence and low-energy neutral excitations of this additional gap indicate a Mott insulating origin. Further, we use simultaneous electrical and Raman spectroscopy measurements to study the phonons scattered by an electric current. At high bias, suspended nanotubes show striking negative differential conductance, attributed to non-equilibrium phonons. We directly observe such "hot" phonon populations in the Raman response and also report preferential electron coupling to one of two optical phonon modes. In addition, using spatially-resolved Raman spectroscopy, we obtain a wealth of local information

  4. Magnetoresistance of a 2D electron gas caused by electron interactions in the transition from the diffusive to the ballistic regime.

    Science.gov (United States)

    Li, L; Proskuryakov, Y Y; Savchenko, A K; Linfield, E H; Ritchie, D A

    2003-02-21

    On a high-mobility 2D electron gas we have observed, in strong magnetic fields (omega(c)tau>1), a parabolic negative magnetoresistance caused by electron-electron interactions in the regime of k(B)Ttau/ variant Planck's over 2pi approximately 1, which is the transition from the diffusive to the ballistic regime. From the temperature dependence of this magnetoresistance the interaction correction to the conductivity deltasigma(ee)(xx)(T) is obtained in the situation of a long-range fluctuation potential and strong magnetic field. The results are compared with predictions of the new theory of interaction-induced magnetoresistance.

  5. Van Allen Probes observations of prompt MeV radiation belt electron acceleration in nonlinear interactions with VLF chorus

    Science.gov (United States)

    Foster, J. C.; Erickson, P. J.; Omura, Y.; Baker, D. N.; Kletzing, C. A.; Claudepierre, S. G.

    2017-01-01

    Prompt recovery of MeV (millions of electron Volts) electron populations in the poststorm core of the outer terrestrial radiation belt involves local acceleration of a seed population of energetic electrons in interactions with VLF chorus waves. Electron interactions during the generation of VLF rising tones are strongly nonlinear, such that a fraction of the relativistic electrons at resonant energies are trapped by waves, leading to significant nonadiabatic energy exchange. Through detailed examination of VLF chorus and electron fluxes observed by Van Allen Probes, we investigate the efficiency of nonlinear processes for acceleration of electrons to MeV energies. We find through subpacket analysis of chorus waveforms that electrons with initial energy of hundreds of keV to 3 MeV can be accelerated by 50 keV-200 keV in resonant interactions with a single VLF rising tone on a time scale of 10-100 ms.

  6. Asynchronous event-based binocular stereo matching.

    Science.gov (United States)

    Rogister, Paul; Benosman, Ryad; Ieng, Sio-Hoi; Lichtsteiner, Patrick; Delbruck, Tobi

    2012-02-01

    We present a novel event-based stereo matching algorithm that exploits the asynchronous visual events from a pair of silicon retinas. Unlike conventional frame-based cameras, recent artificial retinas transmit their outputs as a continuous stream of asynchronous temporal events, in a manner similar to the output cells of the biological retina. Our algorithm uses the timing information carried by this representation in addressing the stereo-matching problem on moving objects. Using the high temporal resolution of the acquired data stream for the dynamic vision sensor, we show that matching on the timing of the visual events provides a new solution to the real-time computation of 3-D objects when combined with geometric constraints using the distance to the epipolar lines. The proposed algorithm is able to filter out incorrect matches and to accurately reconstruct the depth of moving objects despite the low spatial resolution of the sensor. This brief sets up the principles for further event-based vision processing and demonstrates the importance of dynamic information and spike timing in processing asynchronous streams of visual events.

  7. Increased Automation in Stereo Camera Calibration Techniques

    Directory of Open Access Journals (Sweden)

    Brandi House

    2006-08-01

    Full Text Available Robotic vision has become a very popular field in recent years due to the numerous promising applications it may enhance. However, errors within the cameras and in their perception of their environment can cause applications in robotics to fail. To help correct these internal and external imperfections, stereo camera calibrations are performed. There are currently many accurate methods of camera calibration available; however, most or all of them are time consuming and labor intensive. This research seeks to automate the most labor intensive aspects of a popular calibration technique developed by Jean-Yves Bouguet. His process requires manual selection of the extreme corners of a checkerboard pattern. The modified process uses embedded LEDs in the checkerboard pattern to act as active fiducials. Images are captured of the checkerboard with the LEDs on and off in rapid succession. The difference of the two images automatically highlights the location of the four extreme corners, and these corner locations take the place of the manual selections. With this modification to the calibration routine, upwards of eighty mouse clicks are eliminated per stereo calibration. Preliminary test results indicate that accuracy is not substantially affected by the modified procedure. Improved automation to camera calibration procedures may finally penetrate the barriers to the use of calibration in practice.

  8. Infrared stereo camera for human machine interface

    Science.gov (United States)

    Edmondson, Richard; Vaden, Justin; Chenault, David

    2012-06-01

    Improved situational awareness results not only from improved performance of imaging hardware, but also when the operator and human factors are considered. Situational awareness for IR imaging systems frequently depends on the contrast available. A significant improvement in effective contrast for the operator can result when depth perception is added to the display of IR scenes. Depth perception through flat panel 3D displays are now possible due to the number of 3D displays entering the consumer market. Such displays require appropriate and human friendly stereo IR video input in order to be effective in the dynamic military environment. We report on a stereo IR camera that has been developed for integration on to an unmanned ground vehicle (UGV). The camera has auto-convergence capability that significantly reduces ill effects due to image doubling, minimizes focus-convergence mismatch, and eliminates the need for the operator to manually adjust camera properties. Discussion of the size, weight, and power requirements as well as integration onto the robot platform will be given along with description of the stand alone operation.

  9. Increased Automation in Stereo Camera Calibration Techniques

    Directory of Open Access Journals (Sweden)

    Brandi House

    2006-08-01

    Full Text Available Robotic vision has become a very popular field in recent years due to the numerous promising applications it may enhance. However, errors within the cameras and in their perception of their environment can cause applications in robotics to fail. To help correct these internal and external imperfections, stereo camera calibrations are performed. There are currently many accurate methods of camera calibration available; however, most or all of them are time consuming and labor intensive. This research seeks to automate the most labor intensive aspects of a popular calibration technique developed by Jean-Yves Bouguet. His process requires manual selection of the extreme corners of a checkerboard pattern. The modified process uses embedded LEDs in the checkerboard pattern to act as active fiducials. Images are captured of the checkerboard with the LEDs on and off in rapid succession. The difference of the two images automatically highlights the location of the four extreme corners, and these corner locations take the place of the manual selections. With this modification to the calibration routine, upwards of eighty mouse clicks are eliminated per stereo calibration. Preliminary test results indicate that accuracy is not substantially affected by the modified procedure. Improved automation to camera calibration procedures may finally penetrate the barriers to the use of calibration in practice.

  10. Stereo topography of Valhalla and Gilgamesh

    Science.gov (United States)

    Schenk, P.; McKinnon, W.; Moore, J.

    1997-03-01

    The geology and morphology of the large multiring impact structures Valhalla and Gilgamesh have been used to infer ways in which the interior structure and properties of the large icy satellites Callisto and Ganymede differ from rocky bodies. These earlier studies were made in the absence of topographic data showing the depths of large impact basins and the degree to which relief has been preserved at large and small scales. Using Voyager stereo images of these basins, we have constructed the first detailed topographic maps of these large basins. These maps reveal the absence of deep topographic depressions, but show that multi-kilometer relief is preserved near the center of Valhalla. Digital Elevation Models (DEM) of these basins were produced using an automated digital stereogrammetry program developed at LPI for use with Voyager and Viking images. The Voyager images used here were obtained from distances of 80,000 to 125,000 km. As a result, the formal vertical resolution for both Valhalla and Gilgamesh maps is about 0.5 km. Relative elevations only are mapped as no global topographic datum exists for the Galilean satellites. In addition, the stereo image models were used to remap the geology and structure of these multiring basins in detail.

  11. Waves near interplanetary shocks observed by STEREO

    Science.gov (United States)

    Aguilar-Rodriguez, E.; Blanco-Cano, X.; Russell, C. T.; Luhmann, J. G.; Krauss-Varban, D.

    2007-12-01

    We investigate the properties of interplanetary shocks that form ahead of virtually all fast propagating coronal mass ejections (CMEs). Understanding the characteristics of these shocks and their surrounding regions is of great interest as they play a major role in the acceleration of solar energetic particles (SEPs). In this work we study low frequency waves upstream and downstream of interplanetary shocks (IP) observed by the twin spacecraft mission STEREO. In the upstream region waves can be generated by ion beams reflected or otherwise energized at the shock. Downstream the wave spectrum may be formed by both, waves generated locally and waves transmitted through the shock.The efficiency of wave generation and wave convection to the shock depends on the shock Mach number, and the angle between the IMF and the shock normal. Waves can disturb the shock and participate in ion acceleration processes. Multi-point STEREO measurements will allow us to study wave characteristics in different regions near IP shocks and determine the effects that these fluctuations have on particle energization.

  12. Investigation of Vortex Structures in Gas-Discharge Nonneutral Electron Plasma: IV. Pulse Ejection of Electrons at the mutual interaction of Vortex Structures

    CERN Document Server

    Kervalishvili, N A

    2015-01-01

    The results of experimental investigations of the ejection of electrons from gas-discharge nonneutral electron plasma at interaction of vortex structures have been given. The periodical approach of vortex structures causes the ejection of electrons both from the vortex structures themselves and from the adjacent regions of electron sheath to the end cathodes of discharge device. The ejection takes place in the form of short and long pulses following each other. The nature of these pulses and the dynamics of interaction of vortex structures at their approach were studied.

  13. Orbital-dependent Electron-Hole Interaction in Graphene and Associated Multi-Layer Structures

    Science.gov (United States)

    Deng, Tianqi; Su, Haibin

    2015-11-01

    We develop an orbital-dependent potential to describe electron-hole interaction in materials with structural 2D character, i.e. quasi-2D materials. The modulated orbital-dependent potentials are also constructed with non-local screening, multi-layer screening, and finite gap due to the coupling with substrates. We apply the excitonic Hamiltonian in coordinate-space with developed effective electron-hole interacting potentials to compute excitons’ binding strength at M (π band) and Γ (σ band) points in graphene and its associated multi-layer forms. The orbital-dependent potential provides a range-separated property for regulating both long- and short-range interactions. This accounts for the existence of the resonant π exciton in single- and bi-layer graphenes. The remarkable strong electron-hole interaction in σ orbitals plays a decisive role in the existence of σ exciton in graphene stack at room temperature. The interplay between gap-opening and screening from substrates shed a light on the weak dependence of σ exciton binding energy on the thickness of graphene stacks. Moreover, the analysis of non-hydrogenic exciton spectrum in quasi-2D systems clearly demonstrates the remarkable comparable contribution of orbital dependent potential with respect to non-local screening process. The understanding of orbital-dependent potential developed in this work is potentially applicable for a wide range of materials with low dimension.

  14. Phonon-electron interactions in piezoelectric semiconductor bulk acoustic wave resonators.

    Science.gov (United States)

    Gokhale, Vikrant J; Rais-Zadeh, Mina

    2014-07-08

    This work presents the first comprehensive investigation of phonon-electron interactions in bulk acoustic standing wave (BAW) resonators made from piezoelectric semiconductor (PS) materials. We show that these interactions constitute a significant energy loss mechanism and can set practical loss limits lower than anharmonic phonon scattering limits or thermoelastic damping limits. Secondly, we theoretically and experimentally demonstrate that phonon-electron interactions, under appropriate conditions, can result in a significant acoustic gain manifested as an improved quality factor (Q). Measurements on GaN resonators are consistent with the presented interaction model and demonstrate up to 35% dynamic improvement in Q. The strong dependencies of electron-mediated acoustic loss/gain on resonance frequency and material properties are investigated. Piezoelectric semiconductors are an extremely important class of electromechanical materials, and this work provides crucial insights for material choice, material properties, and device design to achieve low-loss PS-BAW resonators along with the unprecedented ability to dynamically tune resonator Q.

  15. Study of neutrino interactions with the electronic detectors of the OPERA experiment

    CERN Document Server

    Agafonova, N.; Altinok, O.; Anokhina, A.; Aoki, S.; Ariga, A.; Ariga, T.; Autiero, D.; Badertscher, A.; Bagulya, A.; Bendhabi, A.; Bertolin, A.; Bozza, C.; Brugiere, T.; Brugnera, R.; Brunet, F.; Brunetti, G.; Buontempo, S.; Cazes, A.; Chaussard, L.; Chernyavsky, M.; Chiarella, V.; Chukanov, A.; D'Ambrosio, N.; Dal Corso, F.; De Lellis, G.; del Amo Sanchez, P.; Declais, Y.; De Serio, M.; Di Capua, F.; Di Crescenzo, A.; Di Ferdinando, D.; Di Marco, N.; Dmitrievski, S.; Dracos, M.; Duchesneau, D.; Dusini, S.; Dzhatdoev, T.; Ebert, J.; Egorov, O.; Enikeev, R.; Ereditato, A.; Esposito, L.S.; Favier, J.; Ferber, T.; Fini, R.A.; Frekers, D.; Fukuda, T.; Garfagnini, A.; Giacomelli, G.; Giorgini, M.; Gollnitz, C.; Goldberg, J.; Golubkov, D.; Goncharova, L.; Gornushkin, Y.; Grella, G.; Grianti, F.; Guler, A.M.; Gustavino, C.; Hagner, C.; Hamada, K.; Hara, T.; Hierholzer, M.; Hollnagel, A.; Hoshino, K.; Ieva, M.; Ishida, H.; Jakovcic, K.; Jollet, C.; Juget, F.; Kamiscioglu, M.; Kazuyama, K.; Kim, S.H.; Kimura, M.; Kitagawa, N.; Klicek, B.; Knuesel, J.; Kodama, K.; Komatsu, M.; Kose, U.; Kreslo, I.; Kubota, H.; Lazzaro, C.; Lenkeit, J.; Lippi, I.; Ljubicic, A.; Longhin, A.; Loverre, P.; Lutter, G.; Malgin, A.; Mandrioli, G.; Mannai, K.; Marteau, J.; Matsuo, T.; Matveev, V.; Mauri, N.; Medinaceli, E.; Meisel, F.; Meregaglia, A.; Migliozzi, P.; Mikado, S.; Miyamoto, S.; Monacelli, P.; Morishima, K.; Moser, U.; Muciaccia, M.T.; Naganawa, N.; Naka, T.; Nakamura, M.; Nakano, T.; Naumov, D.; Nikitina, V.; Niwa, K.; Nonoyama, Y.; Ogawa, S.; Okateva, N.; Olchevski, A.; Paniccia, M.; Paoloni, A.; Park, B.D.; Park, I.G.; Pastore, A.; Patrizii, L.; Pennacchio, E.; Pessard, H.; Pretzl, K.; Pilipenko, V.; Pistillo, C.; Polukhina, N.; Pozzato, M.; Pupilli, F.; Rescigno, R.; Roganova, T.; Rokujo, H.; Romano, G.; Rosa, G.; Rostovtseva, I.; Rubbia, A.; Russo, A.; Ryasny, V.; Ryazhskaya, O.; Sato, O.; Sato, Y.; Schembri, A.; Schmidt-Parzefall, W.; Schroeder, H.; Scotto Lavina, L.; Sheshukov, A.; Shibuya, H.; Shoziyoev, G.; Simone, S.; Sioli, M.; Sirignano, C.; Sirri, G.; Song, J.S.; Spinetti, M.; Stanco, L.; Starkov, N.; Stipcevic, M.; Strauss, T.; Strolin, P.; Takahashi, S.; Tenti, M.; Terranova, F.; Tezuka, I.; Tioukov, V.; Tolun, P.; Trabelsi, A.; Tran, T.; Tufanli, S.; Vilain, P.; Vladimirov, M.; Votano, L.; Vuilleumier, J.L.; Wilquet, G.; Wonsak, B.; Yakushev, V.; Yoon, C.S.; Yoshioka, T.; Yoshida, J.; Zaitsev, Y.; Zemskova, S.; Zghiche, A.; Zimmermann, R.

    2011-01-01

    The OPERA experiment is based on a hybrid technology combining electronic detectors and nuclear emulsions. OPERA collected muon-neutrino interactions during the 2008 and 2009 physics runs of the CNGS neutrino beam, produced at CERN with an energy range of about 5-35 GeV. A total of $5.3 \\times 10^{19}$ protons on target equivalent luminosity has been analysed with the OPERA electronic detectors: scintillator strips target trackers and magnetic muon spectrometers equipped with resistive plate gas chambers and drift tubes, allowing a detailed reconstruction of muon-neutrino interactions. Charged Current (CC) and Neutral Current (NC) interactions are identified, using the measurements in the electronic detectors, and the NC/CC ratio is computed. The momentum distribution and the charge of the muon tracks produced in CC interactions are analysed. Calorimetric measurements of the visible energy are performed for both the CC and NC samples. For CC events the Bjorken-$y$ distribution and the hadronic shower profile ...

  16. Noncovalent interactions from electron density topology and solvent effects on spectral properties of Schiff bases

    Science.gov (United States)

    Gandhimathi, S.; Balakrishnan, C.; Theetharappan, M.; Neelakantan, M. A.; Venkataraman, R.

    2017-03-01

    Two Schiff bases were prepared by the condensation of o-allyl substituted 2,4-dihydroxy acetophenone with 1,2-diaminopropane (L1) and ethanediamine (L2) and characterized by elemental analysis, and ESI-MS, IR, UV-Vis, 1H and 13C NMR spectral techniques. The effect of solvents with respect to different polarities on UV-Vis and emission spectra of L1 and L2 was investigated at room temperature show that the compounds exist in keto and enol forms in solution and may be attributed to the intramolecular proton transfer in the ground state. The solute-solvent interactions, change in dipole moment and solvatochromic properties of the compounds were studied based on the solvent polarity parameters. For L1 and L2, the ground and excited state electronic structure calculations were carried out by DFT and TD-DFT at B3LYP/6-311G (d,p) level, respectively. The IR, NMR and electronic absorption spectra computed were compared with the experimental observations. The intramolecular charge transfer within the molecule is evidenced from the HOMO and LUMO energy levels and surface analysis. The noncovalent interactions like hydrogen bonding and van der Waals interactions were identified from the molecular geometry and electron localization function. These interactions in molecules have been studied by using reduced density gradient and graphed by Multiwfn.

  17. Simple method for calibrating omnidirectional stereo with multiple cameras

    Science.gov (United States)

    Ha, Jong-Eun; Choi, I.-Sak

    2011-04-01

    Cameras can give useful information for the autonomous navigation of a mobile robot. Typically, one or two cameras are used for this task. Recently, an omnidirectional stereo vision system that can cover the whole surrounding environment of a mobile robot is adopted. They usually adopt a mirror that cannot offer uniform spatial resolution. In this paper, we deal with an omnidirectional stereo system which consists of eight cameras where each two vertical cameras constitute one stereo system. Camera calibration is the first necessary step to obtain 3D information. Calibration using a planar pattern requires many images acquired under different poses so it is a tedious step to calibrate all eight cameras. In this paper, we present a simple calibration procedure using a cubic-type calibration structure that surrounds the omnidirectional stereo system. We can calibrate all the cameras on an omnidirectional stereo system in just one shot.

  18. Electronic structure contribution to hydrogen bonding interaction of a water dimer

    CERN Document Server

    Zhang, Zhiyuan; Wang, Bo; Wang, Zhigang

    2016-01-01

    Hydrogen bond (H-bond) covalency has recently been observed in ice and liquid water, while the penetrating molecular orbitals (MOs) in the H-bond region of most typical water dimer system, (H2O)2, have also been discovered. However, obtaining the quantitative contribution of these MOs to the H-bond interaction is still problematic. In this work, we introduced the orbital-resolved electron density projected integral (EDPI) along the H-bond to approach this problem. The calculations show that, surprisingly, the electronic occupied orbital (HOMO-4) of (H2O)2 accounts for about 40% of the electron density at the bond critical point. Moreover, the charge transfer analysis visualizes the electron accumulating effect of the orbital interaction within the H-bond between water molecules, supporting its covalent-like character. Our work expands the classical understanding of H-bond with specific contributions from certain MOs, and will also advance further research into such covalency and offer quantitative electronic ...

  19. Electron Bubbles in Superfluid (3) 3 He-A: Exploring the Quasiparticle-Ion Interaction

    Science.gov (United States)

    Shevtsov, Oleksii; Sauls, J. A.

    2017-06-01

    When an electron is forced into liquid ^3He, it forms an "electron bubble", a heavy ion with radius, R˜eq 1.5 nm, and mass, M˜eq 100 m_3, where m_3 is the mass of a ^3He atom. These negative ions have proven to be powerful local probes of the physical properties of the host quantum fluid, especially the excitation spectra of the superfluid phases. We recently developed a theory for Bogoliubov quasiparticles scattering off electron bubbles embedded in a chiral superfluid that provides a detailed understanding of the spectrum of Weyl Fermions bound to the negative ion, as well as a theory for the forces on moving electron bubbles in superfluid ^3He-A (Shevtsov and Sauls in Phys Rev B 94:064511, 2016). This theory is shown to provide quantitative agreement with measurements reported by the RIKEN group (Ikegami et al. in Science 341(6141):59, 2013) for the drag force and anomalous Hall effect of moving electron bubbles in superfluid ^3He-A. In this report, we discuss the sensitivity of the forces on the moving ion to the effective interaction between normal-state quasiparticles and the ion. We consider models for the quasiparticle-ion (QP-ion) interaction, including the hard-sphere potential, constrained random-phase-shifts, and interactions with short-range repulsion and intermediate-range attraction. Our results show that the transverse force responsible for the anomalous Hall effect is particularly sensitive to the structure of the QP-ion potential and that strong short-range repulsion, captured by the hard-sphere potential, provides an accurate model for computing the forces acting on the moving electron bubble in superfluid 3He-A.

  20. Electron Bubbles in Superfluid ^3 He-A: Exploring the Quasiparticle-Ion Interaction

    Science.gov (United States)

    Shevtsov, Oleksii; Sauls, J. A.

    2016-11-01

    When an electron is forced into liquid ^3 He, it forms an "electron bubble", a heavy ion with radius, R˜eq 1.5 nm, and mass, M˜eq 100 m_3 , where m_3 is the mass of a ^3 He atom. These negative ions have proven to be powerful local probes of the physical properties of the host quantum fluid, especially the excitation spectra of the superfluid phases. We recently developed a theory for Bogoliubov quasiparticles scattering off electron bubbles embedded in a chiral superfluid that provides a detailed understanding of the spectrum of Weyl Fermions bound to the negative ion, as well as a theory for the forces on moving electron bubbles in superfluid ^3 He-A (Shevtsov and Sauls in Phys Rev B 94:064511, 2016). This theory is shown to provide quantitative agreement with measurements reported by the RIKEN group (Ikegami et al. in Science 341(6141):59, 2013) for the drag force and anomalous Hall effect of moving electron bubbles in superfluid ^3 He-A. In this report, we discuss the sensitivity of the forces on the moving ion to the effective interaction between normal-state quasiparticles and the ion. We consider models for the quasiparticle-ion (QP-ion) interaction, including the hard-sphere potential, constrained random-phase-shifts, and interactions with short-range repulsion and intermediate-range attraction. Our results show that the transverse force responsible for the anomalous Hall effect is particularly sensitive to the structure of the QP-ion potential and that strong short-range repulsion, captured by the hard-sphere potential, provides an accurate model for computing the forces acting on the moving electron bubble in superfluid 3 He-A.

  1. Isotope effect on electron-phonon interaction in the multiband superconductor MgB2

    Science.gov (United States)

    Mou, Daixiang; Manni, Soham; Taufour, Valentin; Wu, Yun; Huang, Lunan; Bud'ko, S. L.; Canfield, P. C.; Kaminski, Adam

    2016-04-01

    We investigate the effect of isotope substitution on the electron-phonon interaction in the multiband superconductor MgB2 using tunable laser-based angle-resolved photoemission spectroscopy. The kink structure around 70 meV in the σ band, which is caused by electron coupling to the E2 g phonon mode, is shifted to higher binding energy by ˜3.5 meV in Mg 10B2 and the shift is not affected by superconducting transition. These results serve as the benchmark for investigations of isotope effects in known, unconventional superconductors and newly discovered superconductors where the origin of pairing is unknown.

  2. Wakefield evolution and electron acceleration in interaction of frequency-chirped laser pulse with inhomogeneous plasma

    Science.gov (United States)

    Rezaei-Pandari, M.; Niknam, A. R.; Massudi, R.; Jahangiri, F.; Hassaninejad, H.; Khorashadizadeh, S. M.

    2017-02-01

    The nonlinear interaction of an ultra-short intense frequency-chirped laser pulse with an underdense plasma is studied. The effects of plasma inhomogeneity and laser parameters such as chirp, pulse duration, and intensity on plasma density and wakefield evolutions, and electron acceleration are examined. It is found that a properly chirped laser pulse could induce a stronger laser wakefield in an inhomogeneous plasma and result in higher electron acceleration energy. It is also shown that the wakefield amplitude is enhanced by increasing the slope of density in the inhomogeneous plasma.

  3. Chirped Auger electron emission due to field-assisted post-collision interaction

    Directory of Open Access Journals (Sweden)

    Bonitz M.

    2013-03-01

    Full Text Available We have investigated the Auger decay in the temporal domain by applying a terahertz streaking light field. Xenon and krypton atoms were studied by implementing the free-electron laser in Hamburg (FLASH as well as a source of high-order harmonic radiation combined with terahertz pulses from an optical rectification source. The observed linewidth asymmetries in the streaked spectra suggest a chirped Auger electron emission which is understood in terms of field-assisted post-collision interaction. The experimentally obtained results agree well with model calculations.

  4. Extreme field limits in the interaction of laser light with ultrarelativistic electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bulanov, S. V.; Esirkepov, T. Zh.; Hayashi, Y.; Kando, M.; Kiriyama, H.; Koga, J.; Kondo, K.; Kotaki, H.; Pirozhkov, A.; Bulanov, S. S.; Zhidkov, A.; Chen, P.; Neely, D.; Kato, Y.; Narozhny, N. B.; Korn, G. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); University of California, Berkeley, CA 94720 (United States); Osaka University, Osaka 565-0871 (Japan); National Taiwan University, Taipei 10617, Taiwan (China); Central Laser Facility, STFC, Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Graduate School for the Creation of New Photonics Industries, Hamamatsu, Shizuoka 431-1202 (Japan); Moscow Engineering Physics Institute (State University), Moscow 115409 (Russian Federation); Max-Planck-Institut fuer Quantenoptik, Garching 85748 (Germany) and ELI Beamline Facility, Institute of Physics, CAS, Prague 18221 (Czech Republic)

    2012-07-11

    The critical electric field of quantum electrodynamics is so strong that it produces electron-positron pairs from vacuum, converting the energy of light into matter. This field has become feasible through the construction of extremely high power lasers or/and with the sophisticated use of nonlinear processes in relativistic plasmas. A feasibility of the experiments on the collision of laser light and high intensity electromagnetic pulses, generated by relativistic flying mirrors, with relativistic electrons for the studying of extreme field limits in the nonlinear interaction of electromagnetic waves is discussed.

  5. Towards understanding the influence of electron-gas interactions on imaging in an environmental TEM

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal; Boothroyd, Chris; Beleggia, Marco

    2011-01-01

    The latest generation of environmental transmission electron microscopes (ETEMs) incorporates aberration correction and monochromation, allowing studies of chemical reactions and growth processes with improved spatial and spectral resolution. These additions to the columns of commercial ETEMs have...... are confined to a thin (typically 50-200 μm thick) slab around the sample, but the electrons interact with the window material (e.g. C, SiN) as well as with the gas and the sample. In addition, the field of view is typically smaller than in a conventional TEM and a limited range of sample geometries can...

  6. Coulomb scattering in a 2D interacting electron gas and production of EPR pairs.

    Science.gov (United States)

    Saraga, D S; Altshuler, B L; Loss, Daniel; Westervelt, R M

    2004-06-18

    We propose a setup to generate nonlocal spin Einstein-Podolsky-Rosen pairs via pair collisions in a 2D interacting electron gas, based on constructive two-particle interference in the spin-singlet channel at the pi/2 scattering angle. We calculate the scattering amplitude via the Bethe-Salpeter equation in the ladder approximation and small r(s) limit and find that the Fermi sea leads to a substantial renormalization of the bare scattering process. From the scattering length, we estimate the current of spin-entangled electrons and show that it is within experimental reach.

  7. Combining configuration interaction with perturbation theory for atoms with large number of valence electrons

    CERN Document Server

    Dzuba, V A; Harabati, C; Flambaum, V V

    2016-01-01

    A version of the configuration interaction (CI) method is developed which treats highly excited many-electron basis states perturbatively, so that their inclusion does not affect the size of the CI matrix. This removes, at least in principle, the main limitation of the CI method in dealing with many-electron atoms or ions. We perform calculations of the spectra of iodine and its ions, tungsten, and ytterbium as examples of atoms with open $s$, $p$, $d$ and $f$-shells. Good agreement of the calculated data with experiment illustrates the power of the method. Its advantages and limitations are discussed.

  8. 2010 Electron Donor-Acceptor Interactions Gordon Research Conference, August 8 - 13, 2010.

    Energy Technology Data Exchange (ETDEWEB)

    Gerald Meyer

    2010-08-18

    The Gordon Research Conference on Electron Donor Acceptor Interactions (GRC EDAI) presents and advances the current frontiers in experimental and theoretical studies of Electron Transfer Processes and Energy Conversion. The fundamental concepts underpinning the field of electron transfer and charge transport phenomena are understood, but fascinating experimental discoveries and novel applications based on charge transfer processes are expanding the discipline. Simultaneously, global challenges for development of viable and economical alternative energy resources, on which many researchers in the field focus their efforts, are now the subject of daily news headlines. Enduring themes of this conference relate to photosynthesis, both natural and artificial, and solar energy conversion. More recent developments include molecular electronics, optical switches, and nanoscale charge transport structures of both natural (biological) and man-made origin. The GRC EDAI is one of the major international meetings advancing this field, and is one of the few scientific meetings where fundamental research in solar energy conversion has a leading voice. The program includes sessions on coupled electron transfers, molecular solar energy conversion, biological and biomimetic systems, spin effects, ultrafast reactions and technical frontiers as well as electron transport in single molecules and devices. In addition to disseminating the latest advances in the field of electron transfer processes, the conference is an excellent forum for scientists from different disciplines to meet and initiate new directions; for scientists from different countries to make contacts; for young scientists to network and establish personal contacts with other young scientists and with established scientists who, otherwise, might not have the time to meet young people. The EDAI GRC also features an interactive atmosphere with lively poster sessions, a few of which are selected for oral presentations.

  9. Interaction of electron beams with optical nanostructures and metamaterials: from coherent photon sources towards shaping the wave function

    Science.gov (United States)

    Talebi, Nahid

    2017-10-01

    Investigating the interaction of electron beams with materials and light has been a field of research for more than a century. The field was advanced theoretically by the rise of quantum mechanics and technically by the introduction of electron microscopes and accelerators. It is possible nowadays to uncover a multitude of information from electron-induced excitations in matter by means of advanced techniques like holography, tomography, and, most recently, photon-induced near-field electron microscopy. The question is whether the interaction can be controlled in an even, more efficient way in order to unravel important questions like modal decomposition of the electron-induced polarization by performing experiments with better spatial, temporal, and energy resolutions. This review discusses recent advances in controlling electron and light interactions at the nanoscale. Theoretical and numerical aspects of the interaction of electrons with nanostructures and metamaterials will be discussed with the aim of understanding the mechanisms of radiation in the interaction of electrons with even more sophisticated structures. Based on these mechanisms of radiation, state-of-the art and novel electron-driven few-photon sources will be discussed. Applications of such sources to gain an understanding of quantum optical effects and also to perform spectral interferometry with electron microscopes will be covered. In an inverse approach, as in the case of the inverse Smith–Purcell effect, laser-induced excitations of nanostructures can cause electron beams traveling in the near-field of such structures to accelerate, provided a synchronization criterion is satisfied. This effect is the basis for linear dielectric and metallic electron accelerators. Moreover, acceleration is accompanied by bunching of the electrons. When single electrons are considered, an efficient design of nanostructures can lead to the shaping of the electron wave function travelling adjacent to them, for

  10. Very High Energy Electron-positron Colliding Beams for the Study of the Weak Interactions

    CERN Document Server

    Richter, B

    1976-01-01

    We consider the design of very high energy electron-positron colliding-beam storage rings for use primarily as a tool for investigating the weak interactions. These devices appear to be a very powerful tool for determining the properties of these interactions. Experimental possibilities are described, a cost minimization technique is developed, and a model machine is designed to operate at centre-of-mass energies of up to 200 GeV. Costs are discussed, and problems delineated that must be solved before such a machine can be finally designed.

  11. Payment Solutions for Services in Interactive TV : A Comparative Evaluation of Electronic Payment Systems

    OpenAIRE

    Aminoff, Fredrik; Dettel, Johan

    2004-01-01

    The market for digital TV is developing and some industry actors focus on interactive TV. Interactive content and services that previously only were able to use through a standard PC are now available to use through the TV set. To distribute the services to the TV a so called set top box with broadband connection needs to be used. Such a box can be described as a unit where a standard PC and a digital TV receptor are integrated. This thesis aims to investigate the market for electronic paymen...

  12. Electron-mediated nuclear-spin interactions between distant nitrogen-vacancy centers.

    Science.gov (United States)

    Bermudez, A; Jelezko, F; Plenio, M B; Retzker, A

    2011-10-07

    We propose a scheme enabling controlled quantum coherent interactions between separated nitrogen-vacancy centers in diamond in the presence of strong magnetic fluctuations. The proposed scheme couples nuclear qubits employing the magnetic dipole-dipole interaction between the electron spins and, crucially, benefits from the suppression of the effect of environmental magnetic field fluctuations thanks to a strong microwave driving. This scheme provides a basic building block for a full-scale quantum-information processor or quantum simulator based on solid-state technology.

  13. Electron-Mediated Nuclear-Spin Interactions Between Distant NV Centers

    CERN Document Server

    Bermudez, A; Plenio, M B; Retzker, A

    2011-01-01

    We propose a scheme enabling controlled quantum coherent interactions between separated nitrogen-vacancy centers in diamond in the presence of strong magnetic fluctuations. The proposed scheme couples nuclear qubits employing the magnetic dipole-dipole interaction between the electron spins and, crucially, benefits from the suppression of the effect of environmental magnetic field fluctuations thanks to a strong microwave driving. This scheme provides a basic building block for a full-scale quantum information processor or quantum simulator based on solid-state technology.

  14. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.

    Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  15. Considerations for the Use of STEREO-HI Data for Astronomical Studies

    Science.gov (United States)

    Tappin, S. J.

    2017-04-01

    Recent refinements to the photometric calibrations of the Heliospheric Imagers (HI) on board the Solar TErrestrial RElations Observatory (STEREO) have revealed a number of subtle effects in the measurement of stellar signals with those instruments. These effects need to be considered in the interpretation of STEREO-HI data for astronomy. In this paper we present an analysis of these effects and how to compensate for them when using STEREO-HI data for astronomical studies. We determine how saturation of the HI CCD detectors affects the apparent count rates of stars after the on-board summing of pixels and exposures. Single-exposure calibration images are analyzed and compared with binned and summed science images to determine the influence of saturation on the science images. We also analyze how the on-board cosmic-ray scrubbing algorithm affects stellar images. We determine how this interacts with the variations of instrument pointing to affect measurements of stars. We find that saturation is a significant effect only for the brightest stars, and that its onset is gradual. We also find that degraded pointing stability, whether of the entire spacecraft or of the imagers, leads to reduced stellar count rates and also increased variation thereof through interaction with the on-board cosmic-ray scrubbing algorithm. We suggest ways in which these effects can be mitigated for astronomical studies and also suggest how the situation can be improved for future imagers.

  16. Inverted point-contact spectrum of electron-phonon interactions in arsenic homocontacts

    Science.gov (United States)

    Khotkevich, A. V.; Krasnyi, A. S.

    2016-04-01

    The point-contact (microcontact) spectra (second derivatives of the current-voltage characteristics) of As/As point homocontacts are measured at liquid helium temperatures. Inversion of the sign of the point-contact spectrum is observed as a result of the destruction of electron localization in the arsenic contacts owing to electron-phonon interactions. The point-contact spectrum contains two major peaks at energies of 10 and 25 meV. The boundary of the single-phonon part of the spectrum corresponds to 34 meV. This agrees with available data on the density of phonon states. Assuming that the inverted point-contact spectrum reflects features of the electro-phonon interaction spectral function, the mean-square frequency of the phonons is calculated and the Debye temperature is estimated.

  17. Modeling of molecular photocells: Application to two-level photovoltaic system with electron-hole interaction.

    Science.gov (United States)

    Nemati Aram, Tahereh; Anghel-Vasilescu, Petrutza; Asgari, Asghar; Ernzerhof, Matthias; Mayou, Didier

    2016-09-28

    We present a novel simple model to describe molecular photocells where the energy conversion process takes place by a single molecular donor-acceptor complex attached to electrodes. By applying quantum scattering theory, an open quantum system method, the coherent molecular photocell is described by a wave function. We analyze photon absorption, energy conversion, and quantum yield of a molecular photocell by considering the effects of electron-hole interaction and non-radiative recombination. We model the exciton creation, dissociation, and subsequent effects on quantum yield in the energy domain. We find that depending on the photocell structure, the electron-hole interaction can normally decrease or abnormally increase the cell efficiency. The proposed model helps to understand the mechanisms of molecular photocells, and it can be used to optimize their yield.

  18. Tuning Electron Spin States in Quantum Dots by Spin-Orbit Interactions

    Institute of Scientific and Technical Information of China (English)

    LIU Yu; CHENG Fang

    2011-01-01

    @@ We theoretically investigate the influence of both Rashba spin-orbit interaction (RSOI) and Dresselhaus spin- orbit interaction (DSOI) on electron spin states, electron distribution and the optical absorption of a quantum dot.Our theoretical results show that the interplay between RSOI and DSOI results in an effective periodic potential, which consequently breaks the rotational symmetry and makes the quantum dot behave like two laterally coupled quantum dots.In the presence of RSOI and/or DSOI the spin is no longer a conserved quantity and its magnitude can be tuned by changing the strength of RSOI and/or DSOI.By reversing the direction of the perpendicular electric field, we can rotate the spatial distribution.This property provides us with a new way to control quantum states in a quantum dot by electrical means.

  19. Interaction between in vivo bioluminescence and extracellular electron transfer in Shewanella woodyi via charge and discharge.

    Science.gov (United States)

    Tian, Xiaochun; Zhao, Feng; You, Lexing; Wu, Xuee; Zheng, Zhiyong; Wu, Ranran; Jiang, Yanxia; Sun, Shigang

    2017-01-18

    Extracellular electron transfer (EET) and bioluminescence are both important for microbial growth and metabolism, but the mechanism of interaction between EET and bioluminescence is poorly understood. Herein, we demonstrate an exclusively respiratory luminous bacterium, Shewanella woodyi, which possesses EET ability and electron communication at the interface of S. woodyi and solid substrates via charge and discharge methods. Using an electro-chemiluminescence apparatus, our results confirmed that the FMN/FMNH2 content and the redox status of cytochrome c conjointly regulated the bioluminescence intensity when the potential of an indium-tin oxide electrode was changed. More importantly, this work revealed that there is an interaction between the redox reaction of single cells and bioluminescence of group communication via the EET pathway.

  20. Unified dynamics of electrons and photons via Zitterbewegung and spin-orbit interaction

    Science.gov (United States)

    Leary, C. C.; Smith, Karl H.

    2014-02-01

    We show that when an electron or photon propagates in a cylindrically symmetric waveguide, it experiences both a Zitterbewegung effect and a spin-orbit interaction leading to identical propagation dynamics for both particles. Applying a unified perturbative approach to both particles simultaneously, we find that to first order in perturbation theory, their Hamiltonians each contain identical Darwin (Zitterbewegung) and spin-orbit terms, resulting in the unification of their dynamics. The presence of the Zitterbewegung effect may be interpreted physically as the delocalization of the electron on the scale of its Compton wavelength, or the delocalization of the photon on the scale of its wavelength in the waveguide. The presence of the spin-orbit interaction leads to the prediction of several rotational effects: the spatial or time evolution of either particle's spin or polarization vector is controlled by the sign of its orbital angular momentum quantum number or, conversely, its spatial wave function is controlled by its spin angular momentum.

  1. Thermalisation and hard X-ray bremsstrahlung efficiency of self-interacting solar flare fast electrons

    CERN Document Server

    Galloway, R K; MacKinnon, A L; Brown, J C

    2010-01-01

    Most theoretical descriptions of the production of solar flare bremsstrahlung radiation assume the collision of dilute accelerated particles with a cold, dense target plasma, neglecting interactions of the fast particles with each other. This is inadequate for situations where collisions with this background plasma are not completely dominant, as may be the case in, for example, low-density coronal sources. We aim to formulate a model of a self-interacting, entirely fast electron population in the absence of a dense background plasma, to investigate its implications for observed bremsstrahlung spectra and the flare energy budget. We derive approximate expressions for the time-dependent distribution function of the fast electrons using a Fokker-Planck approach. We use these expressions to generate synthetic bremsstrahlung X-ray spectra as would be seen from a corresponding coronal source. We find that our model qualitatively reproduces the observed behaviour of some flares. As the flare progresses, the model's...

  2. A Re-interpretation of the STEREO/STE Observations and it's Consequences

    CERN Document Server

    Hsieh, K C; Giacalone, J; Jokipii, J R; Kota, J; Larson, D E; Lin, R P; Luhmann, J G; Wang, L

    2009-01-01

    We present an alternate interpretation of recent STEREO/STE observations that were originally attributed to energetic neutral atoms (ENA) from the heliosheath. The signal attributed to the diffuse ENA source instead shows the characteristics of a point source. We point out that the peak intensity seen by STEREO/STE is centered at the ecliptic longitude of the bright X-ray source Sco X-1. The observed energy spectrum and intensity are also consistent with the X-rays from Sco X-1. The problem of energy dissipation at the solar wind termination shock remains unsolved while current understanding of the interaction between the solar wind and interstellar wind awaits future observations.

  3. The weak π − π interaction originated resonant tunneling and fast switching in the carbon based electronic devices

    Directory of Open Access Journals (Sweden)

    Jun He

    2012-03-01

    Full Text Available By means of the nonequilibrium Green's functions and the density functional theory, we have investigated the electronic transport properties of C60 based electronic device with different intermolecular interactions. It is found that the electronic transport properties vary with the types of the interaction between two C60 molecules. A fast electrical switching behavior based on negative differential resistance has been found when two molecules are coupled by the weak π − π interaction. Compared to the solid bonding, the weak interaction is found to induce resonant tunneling, which is responsible for the fast response to the applied electric field and hence the velocity of switching.

  4. Locating the neutrino interaction vertex with the help of electronic detectors in the OPERA experiment

    Science.gov (United States)

    Gornushkin, Yu. A.; Dmitrievsky, S. G.; Chukanov, A. V.

    2015-01-01

    The OPERA experiment is designed for the direct observation of the appearance of ντ from νμ → ντ oscillation in a νμ beam. A description of the procedure of neutrino interaction vertex localization (Brick Finding) by electronic detectors of a hybrid OPERA setup is presented. The procedure includes muon track and hadronic shower axis reconstruction and a determination of the target bricks with the highest probability to contain the vertex.

  5. Perturbation Theory for Interacting Electrons in a Quantum Dot under Strong Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    GU Yun-Ting; RUAN Wen-Ying; LI Quan; CAI Min; CHAN Kok-Sam

    2001-01-01

    The quantum spectrum of interacting electrons confined in a parabolic dot in two dimensions is obtained by employing the perturbation theory. Comparison with the existing analytical results has been made. We show that while the widely used second-order perturbation significantly underestimates the ground state energies, the results including higher orders of perturbation are highly accurate within the B-field range of experimental interest.

  6. PIC simulations of the production of high-quality electron beams via laser-plasma interaction

    Energy Technology Data Exchange (ETDEWEB)

    Benedetti, C. [Department of Physics, University of Bologna and INFN/Bologna, Via Irnerio 46, 40126 Bologna (Italy)], E-mail: carlo.benedetti@bo.infn.it; Londrillo, P. [INAF, Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna (Italy); Petrillo, V.; Serafini, L. [INFN/Milano, Via Celoria 14, 10133 Milano (Italy); Sgattoni, A. [Department of Physics, University of Bologna and INFN/Bologna, Via Irnerio 46, 40126 Bologna (Italy); Tomassini, P. [INFN/Milano, Via Celoria 14, 10133 Milano (Italy); Turchetti, G. [Department of Physics, University of Bologna and INFN/Bologna, Via Irnerio 46, 40126 Bologna (Italy)

    2009-09-01

    We present some numerical studies and parameter scans performed with the electromagnetic, relativistic, fully self-consistent Particle-In-Cell (PIC) code ALaDyn (Acceleration by LAser and DYNamics of charged particles), concerning the generation of a low emittance, high charge and low momentum spread electron bunch from laser-plasma interaction in the Laser WakeField Acceleration (LWFA) regime, in view of achieving beam brightness of interest for FEL applications.

  7. Electron-hole interaction and optical excitations in solids, surfaces, and polymers

    OpenAIRE

    Louie, S. G.

    2001-01-01

    The optical properties of a variety of materials have been calculated using a recently developed ab initio method based on solving the Bethe-Salpeter equation of the two-particle Green's functions. Relevant self-energy and electron-hole interaction effects are included from first-principles. Results on selected semiconductors, insulators, surfaces, and conjugated polymers are discussed. In many of these systems, excitonic effects are shown to dramatically alter the excitation energies a...

  8. Radiation reaction effects on the interaction of an electron with an intense laser pulse.

    Science.gov (United States)

    Kravets, Yevgen; Noble, Adam; Jaroszynski, Dino

    2013-07-01

    Radiation reaction effects will play an important role in near-future laser facilities, yet their theoretical description remains obscure. We explore the Ford-O'Connell equation for radiation reaction, and discuss its relation to other commonly used treatments. By analyzing the interaction of a high energy electron in an intense laser pulse, we find that radiation reaction effects prevent the particle from accessing a regime in which the Landau-Lifshitz approximation breaks down.

  9. Van Hove correlation functions in an interacting electron gas: Equation-of-motion approach

    Science.gov (United States)

    Schinner, Andreas; Bachlechner, Martina E.

    1992-10-01

    An extension of the classical van Hove correlation functions to a three-dimensional system of identical fermions is investigated, taking into account interaction effects. This is done within the framework of a Singwi-Tosi-Land-Sjölander-like static local-field approximation, combined with second-order effects of plasmon damping. As a main result the relaxation of the Fermi hole around an instantaneously removed electron is presented.

  10. Interaction-induced huge magnetoresistance in a high mobility two-dimensional electron gas

    Energy Technology Data Exchange (ETDEWEB)

    Bockhorn, L.; Haug, R. J. [Institut für Festkörperphysik, Leibniz Universität Hannover, D-30167 Hannover (Germany); Gornyi, I. V. [Institut für Nanotechnologie, Karlsruher Institut of Technology, D-76021 Karlsruhe (Germany); Schuh, D. [Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D-93053 Regensburg (Germany); Wegscheider, W. [ETH Zürich (Switzerland)

    2013-12-04

    A strong negative magnetoresistance is observed in a high-mobility two-dimensional electron gas in a GaAs/Al{sub 0.3}Ga{sub 0.7}As quantum well. We discuss that the negative magnetoresistance consists of a small peak induced by a combination of two types of disorder and a huge magnetoresistance explained by the interaction correction to the conductivity for mixed disorder.

  11. Local Classical and Quantum Criticality due to Electron-Vibration Interaction

    OpenAIRE

    2009-01-01

    We study the local classical and quantum critical properties of electron-vibration interaction, represented by the Yu-Anderson model. It exhibits an instability, similar to the Wentzel-Bardeen singularity, whose nature resembles to weakly first order quantum phase transitions at low temperatures, and crosses over to Gaussian behaviour with increasing temperature. We determine the dominant energy scale separating the quantum from classical criticality, study the effect of dissipation and analy...

  12. Electron-hole interaction and optical excitations in solids, surfaces, and polymers

    OpenAIRE

    Louie, S. G.

    2001-01-01

    The optical properties of a variety of materials have been calculated using a recently developed ab initio method based on solving the Bethe-Salpeter equation of the two-particle Green's functions. Relevant self-energy and electron-hole interaction effects are included from first-principles. Results on selected semiconductors, insulators, surfaces, and conjugated polymers are discussed. In many of these systems, excitonic effects are shown to dramatically alter the excitation energies a...

  13. Growth of the energy spread due to the radiative interaction in a short electron bunch moving in an undulator

    CERN Document Server

    Saldin, E L; Yurkov, M V

    1999-01-01

    This paper presents investigations of the longitudinal radiative force in an electron bunch moving in an undulator (wiggler). An analytical solution is obtained for a Gaussian longitudinal bunch profile. Radiative interaction of the particles in an intense microbunch induces a correlated energy spread in the electron beam. Numerical estimates presented in this paper show that this effect can be important for free electron lasers.

  14. Dynamics of electron bunches at the laser-plasma interaction in the bubble regime

    Science.gov (United States)

    Maslov, V. I.; Svystun, O. M.; Onishchenko, I. N.; Tkachenko, V. I.

    2016-09-01

    The multi-bunches self-injection, observed in laser-plasma accelerators in the bubble regime, affects the energy gain of electrons accelerated by laser wakefield. However, understanding of dynamics of the electron bunches formed at laser-plasma interaction may be challenging. We present here the results of fully relativistic electromagnetic particle-in-cell (PIC) simulation of laser wakefield acceleration driven by a short laser pulse in an underdense plasma. The trapping and acceleration of three witness electron bunches by the bubble-like structures were observed. It has been shown that with time the first two witness bunches turn into drivers and contribute to acceleration of the last witness bunch.

  15. Modeling Electronic-Nuclear Interactions for Excitation Energy Transfer Processes in Light-Harvesting Complexes.

    Science.gov (United States)

    Lee, Mi Kyung; Coker, David F

    2016-08-18

    An accurate approach for computing intermolecular and intrachromophore contributions to spectral densities to describe the electronic-nuclear interactions relevant for modeling excitation energy transfer processes in light harvesting systems is presented. The approach is based on molecular dynamics (MD) calculations of classical correlation functions of long-range contributions to excitation energy fluctuations and a separate harmonic analysis and single-point gradient quantum calculations for electron-intrachromophore vibrational couplings. A simple model is also presented that enables detailed analysis of the shortcomings of standard MD-based excitation energy fluctuation correlation function approaches. The method introduced here avoids these problems, and its reliability is demonstrated in accurate predictions for bacteriochlorophyll molecules in the Fenna-Matthews-Olson pigment-protein complex, where excellent agreement with experimental spectral densities is found. This efficient approach can provide instantaneous spectral densities for treating the influence of fluctuations in environmental dissipation on fast electronic relaxation.

  16. Dynamics of electron bunches at the laser–plasma interaction in the bubble regime

    Energy Technology Data Exchange (ETDEWEB)

    Maslov, V.I., E-mail: vmaslov@kipt.kharkov.ua; Svystun, O.M., E-mail: svistun_elena@mail.ru; Onishchenko, I.N.; Tkachenko, V.I.

    2016-09-01

    The multi-bunches self-injection, observed in laser–plasma accelerators in the bubble regime, affects the energy gain of electrons accelerated by laser wakefield. However, understanding of dynamics of the electron bunches formed at laser–plasma interaction may be challenging. We present here the results of fully relativistic electromagnetic particle-in-cell (PIC) simulation of laser wakefield acceleration driven by a short laser pulse in an underdense plasma. The trapping and acceleration of three witness electron bunches by the bubble-like structures were observed. It has been shown that with time the first two witness bunches turn into drivers and contribute to acceleration of the last witness bunch.

  17. Interactions of a Charged Particle with Parallel Two-Dimensional Quantum Electron Gases

    Institute of Scientific and Technical Information of China (English)

    LI Chun-Zhi; SONG Yuan-Hong; WANG You-Nian

    2008-01-01

    @@ By using the linearized quantum hydrodynamic (QHD) theory, electronic excitations induced by a charged particle moving between or over two parallel two-dimensional quantum electron gases (2DQEG) are investigated. The calculation shows that the influence of the quantum effects on the interaction process should be taken into account. Including the quantum statistical and quantum diffraction effects, the general expressions of the induced potential and the stopping power are obtained. Our simulation results indicate that a V-shaped oscillatory wake potential exists in the electron gases during the test charge intrusion. Meanwhile, double peaks will occur in the stopping power when the distance of two surfaces is smaller and the test charge gets closer to any one of the two sheets.

  18. Robust Mosaicking of Stereo Digital Elevation Models from the Ames Stereo Pipeline

    Science.gov (United States)

    Kim, Tae Min; Moratto, Zachary M.; Nefian, Ara Victor

    2010-01-01

    Robust estimation method is proposed to combine multiple observations and create consistent, accurate, dense Digital Elevation Models (DEMs) from lunar orbital imagery. The NASA Ames Intelligent Robotics Group (IRG) aims to produce higher-quality terrain reconstructions of the Moon from Apollo Metric Camera (AMC) data than is currently possible. In particular, IRG makes use of a stereo vision process, the Ames Stereo Pipeline (ASP), to automatically generate DEMs from consecutive AMC image pairs. However, the DEMs currently produced by the ASP often contain errors and inconsistencies due to image noise, shadows, etc. The proposed method addresses this problem by making use of multiple observations and by considering their goodness of fit to improve both the accuracy and robustness of the estimate. The stepwise regression method is applied to estimate the relaxed weight of each observation.

  19. Interaction induced staggered spin-orbit order in two-dimensional electron gas

    Energy Technology Data Exchange (ETDEWEB)

    Das, Tanmoy [Los Alamos National Laboratory

    2012-06-05

    Decoupling spin and charge transports in solids is among the many prerequisites for realizing spin electronics, spin caloritronics, and spin-Hall effect. Beyond the conventional method of generating and manipulating spin current via magnetic knob, recent advances have expanded the possibility to optical and electrical method which are controllable both internally and externally. Yet, due to the inevitable presence of charge excitations and electrical polarizibility in these methods, the separation between spin and charge degrees of freedom of electrons remains a challenge. Here we propose and formulate an interaction induced staggered spin-orbit order as a new emergent phase of matter. We show that when some form of inherent spin-splitting via Rashba-type spin-orbit coupling renders two helical Fermi surfaces to become significantly nested, a Fermi surface instability arises. To lift this degeneracy, a spontaneous symmetry breaking spin-orbit density wave develops, causing a surprisingly large quasiparticle gapping with chiral electronic states, with no active charge excitations. Since the staggered spin-orbit order is associated with a condensation energy, quantified by the gap value, destroying such spin-orbit interaction costs sufficiently large perturbation field or temperature or de-phasing time. BiAg2 surface state is shown to be a representative system for realizing such novel spin-orbit interaction with tunable and large strength, and the spin-splitting is decoupled from charge excitations.

  20. Quantum control of two interacting electrons in a coupled quantum dot

    Institute of Scientific and Technical Information of China (English)

    Song Hong-Zhou; Zhang Ping; Duan Su-Qing; Zhao Xian-Geng

    2006-01-01

    Quantum-state engineering, i.e. active manipulation over the coherent dynamics of suitable quantum-mechanical systems, has become a fascinating prospect of modern physics. Here we discuss the dynamics of two interacting electrons in a coupled quantum dot driven by an external electric field. The results show that the two quantum dots can be used to prepare a maximally entangled Bell state by changing the strength and duration of an oscillatory electric field. Different from the suggestion made by Loss et al (1998 Phys. Rev. A 57 120), the present entanglement involves the spatial degree of freedom for the two electrons. We also find that the coherent tunnelling suppression discussed by Grossmann et al (1991 Phys. Rev. Lett. 67 516) persists in the two-particle case: i.e. two electrons initially localized in one dot can remain dynamically localized, although the strong Coulomb repulsion prevents them from behaving so. Surprisingly,the interaction enhances the degree of localization to a large extent compared with that in the non-interacting case.This phenomenon is referred to as the Coulomb-enhanced dynamical localization.

  1. Interaction of Metals with Suspended Graphene Observed by Transmission Electron Microscopy.

    Science.gov (United States)

    Zan, Recep; Bangert, Ursel; Ramasse, Quentin; Novoselov, Konstantin S

    2012-04-05

    In this Perspective, we present an overview of how different metals interface with suspended graphene, providing a closer look into the metal-graphene interaction by employing high-resolution transmission electron microscopy, especially using high-angle dark field imaging. All studied metals favor sites on the omnipresent hydrocarbon surface contamination rather than on the clean graphene surface and present nonuniform distributions, which never result in continuous films but instead in clusters or nanocrystals, indicating a weak interaction between the metal and graphene. This behavior can be altered to some degree by surface pretreatment (hydrogenation) and high-temperature vacuum annealing. Graphene etching is observed in a scanning transmission electron microscope (STEM) under high vacuum and 60 kV electron beam acceleration voltage conditions for all metals, except for Au. This unusual metal-mediated etching sheds new light on the metal-graphene interaction; it might explain the observed higher frequency of cluster nucleation for certain transition metals and might have implications regarding controlled nanomanipulation, that is, for self-assembly and sculpturing of future graphene-based devices.

  2. Resonant interactions between discrete phonons in quinhydrone driven by nonlinear electron-phonon coupling

    Science.gov (United States)

    Rury, Aaron S.

    2016-06-01

    This study reports experimental, computational, and theoretical evidence for a previously unobserved coherent phonon-phonon interaction in an organic solid that can be described by the application of Fano's analysis to a case without the presence of a continuum. Using Raman spectroscopy of the hydrogen-bonded charge-transfer material quinhydrone, two peaks appear near 700 cm-1 we assign as phonons whose position and line-shape asymmetry depend on the sample temperature and light scattering excitation energy. Density functional theory calculations find two nearly degenerate phonons possessing frequencies near the values found in experiment that share similar atomic motion out of the aromatic plane of electron donor and acceptor molecules of quinhydrone. Further analytical modeling of the steady-state light scattering process using the Peierls-Hubbard Hamiltonian and time-dependent perturbation theory motivates assignment of the physical origin of the asymmetric features of each peak's line shape to an interaction between two discrete phonons via nonlinear electron-phonon coupling. In the context of analytical model results, characteristics of the experimental spectra upon 2.33 eV excitation of the Raman scattering process are used to qualify the temperature dependence of the magnitude of this coupling in the valence band of quinhydrone. These results broaden the range of phonon-phonon interactions in materials in general while also highlighting the rich physics and fundamental attributes specific to organic solids that may determine their applicability in next generation electronics and photonics technologies.

  3. Frontier orbital interactions of electron pushing and drawing substituents with ferrocenyl group

    Institute of Scientific and Technical Information of China (English)

    姜月顺; 柴向东; 杨文胜; 张东; 曹云伟; 诸真家; 李铁津; Jean-Marie Lehn

    1997-01-01

    The frontier orbital interactions of electron pushing and drawing substituents with ferrocenyl group were analyzed based on the electrochemical,UV visible spectral and spectroelectrochemical results of five ferrocene derivatives,R-Fc-A1(PⅠ),A1-Fc-A1(PⅡ),D-Fc-R (PⅢ),D-Kc-A1(PIV) and D-Fc-A2(PV)(R,CH2OH;A1 CHO;A2,CH=C(CN)2 and D,(C18H37)2N-C6H4-CH=CH) It was found that there are strong interactions of the LUMO (πA) of electron drawing substituents with le2g(dxy,dx2 y2)and e2u of the ferroeenyl group because the energy levels of πA and e2g,C2U of (Cp )2 are close,which lower not only the energy levels of bonded orbits,πA+ and dx2-y2+[πA] of PⅠ,PⅡ,PⅣ and PⅤobviously,but also those of their non-bonded orbu dxy For PⅢ,PⅣ and PⅤ,there are strong interactions of HOMO(πD) of the electron pushing substituent with le of the ferrocenyl group because the levels of πD and e of (Cp)2 are close,which result in the formation of anti-bonded orbit,πD- and bonded orbit

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

    Science.gov (United States)

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

    2016-03-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Scisciò, M.; Antici, P., E-mail: patrizio.antici@polytechnique.edu [INFN-RM1 and SBAI, Università di Roma “La Sapienza,” Via Scarpa 16, 00161 Roma (Italy); INRS-EMT, Université du Québec, 1650 Lionel Boulet, Varennes, Québec J3X 1S2 (Canada); Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L. [INFN-RM1 and SBAI, Università di Roma “La Sapienza,” Via Scarpa 16, 00161 Roma (Italy); Papaphilippou, Y. [CERN, CH 1211 Geneva 23 (Switzerland)

    2016-03-07

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

  6. Electron-acoustic phonon interaction and mobility in stressed rectangular silicon nanowires

    Science.gov (United States)

    Zhu, Lin-Li

    2015-01-01

    We investigate the effects of pre-stress and surface tension on the electron-acoustic phonon scattering rate and the mobility of rectangular silicon nanowires. With the elastic theory and the interaction Hamiltonian for the deformation potential, which considers both the surface energy and the acoustoelastic effects, the phonon dispersion relation for a stressed nanowire under spatial confinement is derived. The subsequent analysis indicates that both surface tension and pre-stress can dramatically change the electron-acoustic phonon interaction. Under a negative (positive) surface tension and a tensile (compressive) pre-stress, the electron mobility is reduced (enhanced) due to the decrease (increase) of the phonon energy as well as the deformation-potential scattering rate. This study suggests an alternative approach based on the strain engineering to tune the speed and the drive current of low-dimensional electronic devices. Project supported by the National Natural Science Foundation of China (Grant Nos. 11472243, 11302189, and 11321202), the Doctoral Fund of Ministry of Education of China (Grant No. 20130101120175), the Zhejiang Provincial Qianjiang Talent Program, China (Grant No. QJD1202012), and the Educational Commission of Zhejiang Province, China (Grant No. Y201223476).

  7. Dynamical control of electron-phonon interactions with high-frequency light

    Science.gov (United States)

    Dutreix, C.; Katsnelson, M. I.

    2017-01-01

    This work addresses the one-dimensional problem of Bloch electrons when they are rapidly driven by a homogeneous time-periodic light and linearly coupled to vibrational modes. Starting from a generic time-periodic electron-phonon Hamiltonian, we derive a time-independent effective Hamiltonian that describes the stroboscopic dynamics up to the third order in the high-frequency limit. This yields nonequilibrium corrections to the electron-phonon coupling that are controllable dynamically via the driving strength. This shows in particular that local Holstein interactions in equilibrium are corrected by antisymmetric Peierls interactions out of equilibrium, as well as by phonon-assisted hopping processes that make the dynamical Wannier-Stark localization of Bloch electrons impossible. Subsequently, we revisit the Holstein polaron problem out of equilibrium in terms of effective Green's functions, and specify explicitly how the binding energy and effective mass of the polaron can be controlled dynamically. These tunable properties are reported within the weak- and strong-coupling regimes since both can be visited within the same material when varying the driving strength. This work provides some insight into controllable microscopic mechanisms that may be involved during the multicycle laser irradiations of organic molecular crystals in ultrafast pump-probe experiments, although it should also be suitable for realizations in shaken optical lattices of ultracold atoms.

  8. Stereo and IMU-Assisted Visual Odometry for Small Robots

    Science.gov (United States)

    2012-01-01

    This software performs two functions: (1) taking stereo image pairs as input, it computes stereo disparity maps from them by cross-correlation to achieve 3D (three-dimensional) perception; (2) taking a sequence of stereo image pairs as input, it tracks features in the image sequence to estimate the motion of the cameras between successive image pairs. A real-time stereo vision system with IMU (inertial measurement unit)-assisted visual odometry was implemented on a single 750 MHz/520 MHz OMAP3530 SoC (system on chip) from TI (Texas Instruments). Frame rates of 46 fps (frames per second) were achieved at QVGA (Quarter Video Graphics Array i.e. 320 240), or 8 fps at VGA (Video Graphics Array 640 480) resolutions, while simultaneously tracking up to 200 features, taking full advantage of the OMAP3530's integer DSP (digital signal processor) and floating point ARM processors. This is a substantial advancement over previous work as the stereo implementation produces 146 Mde/s (millions of disparities evaluated per second) in 2.5W, yielding a stereo energy efficiency of 58.8 Mde/J, which is 3.75 better than prior DSP stereo while providing more functionality.

  9. Application of stereo-imaging technology to medical field.

    Science.gov (United States)

    Nam, Kyoung Won; Park, Jeongyun; Kim, In Young; Kim, Kwang Gi

    2012-09-01

    There has been continuous development in the area of stereoscopic medical imaging devices, and many stereoscopic imaging devices have been realized and applied in the medical field. In this article, we review past and current trends pertaining to the application stereo-imaging technologies in the medical field. We describe the basic principles of stereo vision and visual issues related to it, including visual discomfort, binocular disparities, vergence-accommodation mismatch, and visual fatigue. We also present a brief history of medical applications of stereo-imaging techniques, examples of recently developed stereoscopic medical devices, and patent application trends as they pertain to stereo-imaging medical devices. Three-dimensional (3D) stereo-imaging technology can provide more realistic depth perception to the viewer than conventional two-dimensional imaging technology. Therefore, it allows for a more accurate understanding and analysis of the morphology of an object. Based on these advantages, the significance of stereoscopic imaging in the medical field increases in accordance with the increase in the number of laparoscopic surgeries, and stereo-imaging technology plays a key role in the diagnoses of the detailed morphologies of small biological specimens. The application of 3D stereo-imaging technology to the medical field will help improve surgical accuracy, reduce operation times, and enhance patient safety. Therefore, it is important to develop more enhanced stereoscopic medical devices.

  10. STEREO Space Weather and the Space Weather Beacon

    Science.gov (United States)

    Biesecker, D. A.; Webb, D F.; SaintCyr, O. C.

    2007-01-01

    The Solar Terrestrial Relations Observatory (STEREO) is first and foremost a solar and interplanetary research mission, with one of the natural applications being in the area of space weather. The obvious potential for space weather applications is so great that NOAA has worked to incorporate the real-time data into their forecast center as much as possible. A subset of the STEREO data will be continuously downlinked in a real-time broadcast mode, called the Space Weather Beacon. Within the research community there has been considerable interest in conducting space weather related research with STEREO. Some of this research is geared towards making an immediate impact while other work is still very much in the research domain. There are many areas where STEREO might contribute and we cannot predict where all the successes will come. Here we discuss how STEREO will contribute to space weather and many of the specific research projects proposed to address STEREO space weather issues. We also discuss some specific uses of the STEREO data in the NOAA Space Environment Center.

  11. Acquisition of stereo panoramas for display in VR environments

    KAUST Repository

    Ainsworth, Richard A.

    2011-01-23

    Virtual reality systems are an excellent environment for stereo panorama displays. The acquisition and display methods described here combine high-resolution photography with surround vision and full stereo view in an immersive environment. This combination provides photographic stereo-panoramas for a variety of VR displays, including the StarCAVE, NexCAVE, and CORNEA. The zero parallax point used in conventional panorama photography is also the center of horizontal and vertical rotation when creating photographs for stereo panoramas. The two photographically created images are displayed on a cylinder or a sphere. The radius from the viewer to the image is set at approximately 20 feet, or at the object of major interest. A full stereo view is presented in all directions. The interocular distance, as seen from the viewer\\'s perspective, displaces the two spherical images horizontally. This presents correct stereo separation in whatever direction the viewer is looking, even up and down. Objects at infinity will move with the viewer, contributing to an immersive experience. Stereo panoramas created with this acquisition and display technique can be applied without modification to a large array of VR devices having different screen arrangements and different VR libraries.

  12. Ames stereo pipeline-derived digital terrain models of Mercury from MESSENGER stereo imaging

    Science.gov (United States)

    Fassett, Caleb I.

    2016-12-01

    In this study, 96 digital terrain models (DTMs) of Mercury were created using the Ames Stereo Pipeline, using 1456 pairs of stereo images from the Mercury Dual Imaging System instrument on MESSENGER. Although these DTMs cover only 1% of the surface of Mercury, they enable three-dimensional characterization of landforms at horizontal resolutions of 50-250 m/pixel and vertical accuracy of tens of meters. This is valuable in regions where the more precise measurements from the Mercury Laser Altimeter (MLA) are sparse. MLA measurements nonetheless provide an important geodetic framework for the derived stereo products. These DTMs, which are publicly released in conjunction with this paper, reveal topography of features at relatively small scales, including craters, graben, hollows, pits, scarps, and wrinkle ridges. Measurements from these data indicate that: (1) hollows have a median depth of 32 m, in basic agreement with earlier shadow measurement, (2) some of the deep pits (up to 4 km deep) that are interpreted to form via volcanic processes on Mercury have surrounding rims or rises, but others do not, and (3) some pits have two or more distinct, low-lying interior minima that could represent multiple vents.

  13. Bootstrapping the Coronal Magnetic Field with STEREO

    Science.gov (United States)

    Aschwanden, Markus J.

    2010-05-01

    The 3D coronal magnetic field obtained from stereoscopically triangulated loops has been compared with standard photospheric magnetogram extrapolations. We found a large misalignment of 20-40 deg, depending on the complexity of an AR (Sandman et al. 2009; DeRosa et al. 2009). These studies prove that the magnetic field in the photosphere is not force-free and fundamentally cannot reproduce the coronal magnetic field. Bootstrapping with coronal loop 3D geometries are required to improve modeling of the coronal field. Such coronal field bootstrapping methods are currently developed using stereoscopically triangulated loops from STEREO/EUVI and preliminary results show already a significantly reduced misalignment of 10-20 deg.

  14. 'Snow White' Trench After Scraping (Stereo View)

    Science.gov (United States)

    2008-01-01

    This 3D view from the Surface Stereo Imager on NASA's Phoenix Mars Lander shows the trench informally named 'Snow White.' This anaglyph was taken after a series of scrapings by the lander's Robotic Arm on the 58th Martian day, or sol, of the mission (July 23, 2008). The scrapings were done in preparation for collecting a sample for analysis from a hard subsurface layer where soil may contain frozen water. The trench is 4 to 5 centimeters (about 2 inches) deep, about 23 centimeters (9 inches) wide and about 60 centimeters (24 inches) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  15. Active stereo vision routines using PRISM-3

    Science.gov (United States)

    Antonisse, Hendrick J.

    1992-11-01

    This paper describes work in progress on a set of visual routines and supporting capabilities implemented on the PRISM-3 real-time vision system. The routines are used in an outdoor robot retrieval task. The task requires the robot to locate a donor agent -- a Hero2000 -- which holds the object to be retrieved, to navigate to the donor, to accept the object from the donor, and return to its original location. The routines described here will form an integral part of the navigation and wide-area search tasks. Active perception is exploited to locate the donor using real-time stereo ranging directed by a pan/tilt/verge mechanism. A framework for orchestrating visual search has been implemented and is briefly described.

  16. U(1) chiral symmetry in a one-dimensional interacting electron system with spin

    Science.gov (United States)

    Lee, Taejin

    2016-11-01

    We study a spin-dependent Tomonaga-Luttinger model in one dimension, which describes electron transport through a single barrier. Using the Fermi-Bose equivalence in one dimension, we map the model onto a massless Thirring model with a boundary interaction. A field theoretical perturbation theory for the model has been developed, and the chiral symmetry is found to play an important role. The classical bulk action possesses a global U A (1)4 chiral symmetry because the fermion fields are massless. This global chiral symmetry is broken by the boundary interaction, and the bosonic degrees of freedom, corresponding to a chiral phase transformation, become dynamical. They acquire an additional kinetic action from the fermion path-integral measure and govern the critical behaviors of the physical operators. On the critical line where the boundary interaction becomes marginal, they decouple from the fermi fields. Consequently, the action reduces to the free-field action, which contains only a fermion bilinear boundary mass term as an interaction term. By using a renormalization group analysis, we obtain a new critical line, which differs from the previously known critical lines in the literature. The result of this work implies that the phase diagram of the one-dimensional electron system may have a richer structure than previously thought.

  17. MISR Sees the Sierra Nevadas in Stereo

    Science.gov (United States)

    2000-01-01

    These MISR images of the Sierra Nevada mountains near the California-Nevada border were acquired on August 12, 2000 during Terra orbit 3472. On the left is an image from the vertical-viewing (nadir) camera. On the right is a stereo 'anaglyph' created using the nadir and 45.6-degree forward-viewing cameras, providing a three-dimensional view of the scene when viewed with red/blue glasses. The red filter should be placed over your left eye. To facilitate the stereo viewing, the images have been oriented with north toward the left.Some prominent features are Mono Lake, in the center of the images; Walker Lake, to its left; and Lake Tahoe, near the lower left. This view of the Sierra Nevadas includes Yosemite, Kings Canyon, and Sequoia National Parks. Mount Whitney, the highest peak in the contiguous 48 states (elev. 14,495 feet), is visible near the righthand edge. Above it (to the east), the Owens Valley shows up prominently between the Sierra Nevada and Inyo ranges.Precipitation falling as rain or snow on the Sierras feeds numerous rivers flowing southwestward into the San Joaquin Valley. The abundant fields of this productive agricultural area can be seen along the lower right; a large number of reservoirs that supply water for crop irrigation are apparent in the western foothills of the Sierras. Urban areas in the valley appear as gray patches; among the California cities that are visible are Fresno, Merced, and Modesto.MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

  18. Using linked data for mining drug-drug interactions in electronic health records.

    Science.gov (United States)

    Pathak, Jyotishman; Kiefer, Richard C; Chute, Christopher G

    2013-01-01

    By nature, healthcare data is highly complex and voluminous. While on one hand, it provides unprecedented opportunities to identify hidden and unknown relationships between patients and treatment outcomes, or drugs and allergic reactions for given individuals, representing and querying large network datasets poses significant technical challenges. In this research, we study the use of Semantic Web and Linked Data technologies for identifying drug-drug interaction (DDI) information from publicly available resources, and determining if such interactions were observed using real patient data. Specifically, we apply Linked Data principles and technologies for representing patient data from electronic health records (EHRs) at Mayo Clinic as Resource Description Framework (RDF), and identify potential drug-drug interactions (PDDIs) for widely prescribed cardiovascular and gastroenterology drugs. Our results from the proof-of-concept study demonstrate the potential of applying such a methodology to study patient health outcomes as well as enabling genome-guided drug therapies and treatment interventions.

  19. Copper plasmonics and catalysis: role of electron-phonon interactions in dephasing localized surface plasmons.

    Science.gov (United States)

    Sun, Qi-C; Ding, Yuchen; Goodman, Samuel M; Funke, Hans H; Nagpal, Prashant

    2014-11-07

    Copper metal can provide an important alternative for the development of efficient, low-cost and low-loss plasmonic nanoparticles, and selective nanocatalysts. However, poor chemical stability and lack of insight into photophysics and plasmon decay mechanisms has impeded study. Here, we use smooth conformal ALD coating on copper nanoparticles to prevent surface oxidation, and study dephasing time for localized surface plasmons on different sized copper nanoparticles. Using dephasing time as a figure of merit, we elucidate the role of electron-electron, electron-phonon, impurity, surface and grain boundary scattering on the decay of localized surface plasmon waves. Using our quantitative analysis and different temperature dependent measurements, we show that electron-phonon interactions dominate over other scattering mechanisms in dephasing plasmon waves. While interband transitions in copper metal contributes substantially to plasmon losses, tuning surface plasmon modes to infrared frequencies leads to a five-fold enhancement in the quality factor. These findings demonstrate that conformal ALD coatings can improve the chemical stability for copper nanoparticles, even at high temperatures (>300 °C) in ambient atmosphere, and nanoscaled copper is a good alternative material for many potential applications in nanophotonics, plasmonics, catalysis and nanoscale electronics.

  20. An Extended Model for Interaction Between Left-hand Superluminous Waves and Magnetospheric Electrons

    Institute of Scientific and Technical Information of China (English)

    Xiao Fuliang; Zheng Huinan; Wang Shui

    2005-01-01

    The left-hand superluminous electromagnetic waves, L-O mode and L-X mode, can be excited and observed in the auroral cavity of the Earth during the magnetic storms. The two modes can propagate into outer radiation zone and encounter enhanced resonant interactions with the trapped energetic electrons over a wide range of magnetosphere. A current first-order resonant model is extended to evaluate the stochastic acceleration of electrons by the L-O mode and L-X mode at the higher-order resonance. Similar to the first-order resonance, L-O mode can produce significant acceleration of electrons at the higher harmonic resonances over a wide range of wave normal angles and spatial regions. However, the higher harmonic resonance's contribution for significant electron acceleration by L-X mode is less than that of the first order resonance,with the requirement of higher minimum energies, e.g., ~1 MeV in the outer radiation belt. This indicates that L-O mode may be one of the efficient mechanisms for the stochastic acceleration of electrons within the outer radiation zone.

  1. Relativistic electron beam interaction and $K_{\\alpha}$-generation in solid targets

    CERN Document Server

    Fill, E; Eder, D; Eidmann, K; Saemann, A

    1999-01-01

    When fs laser pulses interact with solid surfaces at intensities I lambda /sup 2/ >10/sup 18/ W/cm/sup 2/ mu m/sup 2/, collimated relativistic electron beams are generated. These electrons can be used for producing intense X-radiation (bremsstrahlung or K/sub alpha /) for pumping an innershell X-ray laser. The basic concept of such a laser involves the propagation of the electron beam in a material which converts electron energy into appropriate pump photons. Using the ATLAS titanium-sapphire laser at Max-Planck-Institut fur Quantenoptik, we investigate the generation of hot electrons and of characteristic radiation in copper. The laser (200 mJ/130 fs) is focused by means of an off-axis parabola to a diameter of about 10 mu m. By varying the position of the focus, we measure the copper K/sub alpha /-yield as a function of intensity in a range from 10/sup 15/ to 2 x 10/sup 18/ W/cm/sup 2/ while keeping the laser pulse energy constant. Surprisingly, the highest emission is obtained at an intensity of about 10/s...

  2. Electronic Zero-Point Oscillations in the Strong-Interaction Limit of Density Functional Theory.

    Science.gov (United States)

    Gori-Giorgi, Paola; Vignale, Giovanni; Seidl, Michael

    2009-04-14

    The exchange-correlation energy in Kohn-Sham density functional theory can be expressed exactly in terms of the change in the expectation of the electron-electron repulsion operator when, in the many-electron Hamiltonian, this same operator is multiplied by a real parameter λ varying between 0 (Kohn-Sham system) and 1 (physical system). In this process, usually called adiabatic connection, the one-electron density is kept fixed by a suitable local one-body potential. The strong-interaction limit of density functional theory, defined as the limit λ→∞, turns out to be like the opposite noninteracting Kohn-Sham limit (λ→0) mathematically simpler than the physical (λ = 1) case and can be used to build an approximate interpolation formula between λ→0 and λ→∞ for the exchange-correlation energy. Here we extend the systematic treatment of the λ→∞ limit [Phys. Rev. A 2007, 75, 042511] to the next leading term, describing zero-point oscillations of strictly correlated electrons, with numerical examples for small spherical atoms. We also propose an improved approximate functional for the zero-point term and a revised interpolation formula for the exchange-correlation energy satisfying more exact constraints.

  3. Runtime Analysis of GPU-Based Stereo Matching

    Directory of Open Access Journals (Sweden)

    Christian Zentner

    2015-11-01

    Full Text Available This paper elaborates on the possibility to leverage the highly parallel nature of GPUs to implement more efficient stereo matching algorithms. Different algorithms have been implemented and compared on the CPU and the GPU in order to show the speedup gained by moving the computation to the graphics card. The results were evaluated for accuracy using the test available on the Middlebury website for stereo vision. An assessment of the runtime performance was done by a script which examined the runtime behaviour of the individual steps of the stereo matching algorithm.

  4. Magnetoresistance of a 2D electron gas caused by electron interactions in the transition from the diffusive to the ballistic regime

    OpenAIRE

    Li, L.; Proskuryakov, Y. Y.; Savchenko, A. K.; Linfield, E.H.; Ritchie, D. A.

    2002-01-01

    On a high-mobility 2D electron gas we have observed, in strong magnetic fields (omega_{c} tau > 1), a parabolic negative magnetoresistance caused by electron-electron interactions in the regime of k_{B} T tau / hbar ~ 1, which is the transition from the diffusive to the ballistic regime. From the temperature dependence of this magnetoresistance the interaction correction to the conductivity delta sigma_{xx}^{ee}(T) is obtained in the situation of a long-range fluctuation potential and strong ...

  5. Monte Carlo simulations of Kα source generated by hot electrons-nanobrush target interactions

    Science.gov (United States)

    Zhao, Jincui; Zheng, Jianhua; Cao, Lihua; Zhao, Zongqing; Li, Shu; Gu, Yuqiu; Liu, Jie

    2016-09-01

    We focus on the transport processes from hot electrons to Kα x-ray emission in a copper nanobrush target. The physics on the enhancement of Kα photon yield and conversion efficiency from laser to Kα x-ray ηL→Kα is studied by combining Monte Carlo simulations and previous particle-in-cell simulation results. Simulation results show that Kα photon yield and electron- Kα photon conversion efficiency ηe-→Kα from nanobrush targets rise gradually and then stay nearly constant. Kα photon yield from the structured nanobrush target increases with peak number density n0, but the yield is a little less than that from the same-size planar target when the electron temperature T =400 keV and n0=1021 cm-3 . It is because the number density of atoms and ions in the nanobrush target is almost one half of the foil target. Compared to the planar target, Kα photons after the nanobrush target are more than those before the target. Because it is easier for the electrons to enter the structured target surface, and Kα x-ray source is produced in the deeper position of the structured nanobrush target. Considering the realistic number of hot electrons produced by laser-nanobrush and -planar targets interaction, Kα photon yield in nanobrush targets has a significant enhancement of over 2-6 folds relative to laser-foil irradiation. The yield and ηL→K α from the nanobrush target are, respectively, 5.42 ×109 sr-1 and 7.32 ×10-5 when laser strength I λ2≈2 ×1018 W cm-2 μm2 . The yield and ηL→Kα decrease gradually with the laser strength, but the values are always higher than that from the planar target. Therefore, the laser-nanobrush target interaction can produce brighter and smaller-size Kα photon source, compared to a planar target.

  6. Vibrational assignment and vibronic interaction for NO3 in the ground electronic state

    Science.gov (United States)

    Hirota, Eizi

    2015-04-01

    Two important problems exist for the NO3 free radical. One is the frequency of the degenerate N-O stretching mode ν3. It has been assigned to a band at 1492 cm-1 (Assignment I), whereas Stanton calculated it by an ab initio MO method to be around 1000 cm-1 (Assignment II). The second concerns an anomalous ν4 progression, which appeared in the photoelectron spectra of the NO3 anion and was accounted for by Herzberg-Teller (H-T) mechanism, but the interaction parameter derived was too large. The present study critically examines Assignment II and the H-T vibronic interaction model against the results of high-resolution infrared (IR) spectroscopy supplemented with dispersed fluorescence (DF), and concludes Assignment I to be correct and the H-T mechanism to be complemented by a new vibronic interaction model, based upon the observations: (1) Stanton's ab initio MO ν3 appeared in neither IR nor DF spectra, (2) only one A-E type subband was present in the Z-ν4 hot band (Z denotes the upper state of the 1492 cm-1 band), at variance with the two predicted by Assignment II, (3) the ℓ-type doubling constant and the first-order Coriolis coupling constant derived for the Z state by assuming Assignment II were not acceptable, and (4) anomalous features expected from the H-T vibronic interaction model for the ν4 fundamental state were not observed at all. Infrared spectroscopic results on a few 2E‧ degenerate states indicated that the first-order Coriolis coupling constant and the effective spin-orbit interaction constant were closely correlated, suggesting that the unpaired electron azimuthal motion was affected much by that of the degenerate vibrational mode. This sort of vibronic interaction has been well known for linear polyatomic free radicals in 2Σ electronic states with a bending mode singly excited. A similar vibronic interaction should be present also in symmetric-top free radicals, where a degenerate vibrational mode is singly excited. However, few examples

  7. Collisionless absorption, hot electron generation, and energy scaling in intense laser-target interaction

    Energy Technology Data Exchange (ETDEWEB)

    Liseykina, T., E-mail: tatyana.tiseykina@uni-rostock.de [Institut für Physik, Universität Rostock, Universitätsplatz 3, 18051 Rostock (Germany); Institute of Computational Technologies SD RAS, Acad. Lavrentjev Ave. 6, 630090 Novosibirsk (Russian Federation); Mulser, P. [Theoretical Quantum Electronics, Technische Universität Darmstadt, 64289 Darmstadt (Germany); Murakami, M. [Institute of Laser Engineering, Osaka University, Osaka 565-0871 (Japan)

    2015-03-15

    Among the various attempts to understand collisionless absorption of intense and superintense ultrashort laser pulses, a whole variety of models and hypotheses has been invented to describe the laser beam target interaction. In terms of basic physics, collisionless absorption is understood now as the interplay of the oscillating laser field with the space charge field produced by it in the plasma. A first approach to this idea is realized in Brunel's model the essence of which consists in the formation of an oscillating charge cloud in the vacuum in front of the target, therefore frequently addressed by the vague term “vacuum heating.” The investigation of statistical ensembles of orbits shows that the absorption process is localized at the ion-vacuum interface and in the skin layer: Single electrons enter into resonance with the laser field thereby undergoing a phase shift which causes orbit crossing and braking of Brunel's laminar flow. This anharmonic resonance acts like an attractor for the electrons and leads to the formation of a Maxwellian tail in the electron energy spectrum. Most remarkable results of our investigations are the Brunel like spectral hot electron distribution at the relativistic threshold, the minimum of absorption at Iλ{sup 2}≅(0.3−1.2)×10{sup 21} Wcm{sup −2}μm{sup 2} in the plasma target with the electron density of n{sub e}λ{sup 2}∼10{sup 23}cm{sup −3}μm{sup 2}, the drastic reduction of the number of hot electrons in this domain and their reappearance in the highly relativistic domain, and strong coupling, beyond expectation, of the fast electron jets with the return current through Cherenkov emission of plasmons. The hot electron energy scaling shows a strong dependence on intensity in the moderately relativistic domain Iλ{sup 2}≅(10{sup 18}−10{sup 20}) Wcm{sup −2}μm{sup 2}, a scaling in vague accordance with current published estimates in the range Iλ{sup 2}≅(0.14−3.5)×10{sup 21}

  8. Schrödinger electrons interacting with optical gratings: quantum mechanical study of the inverse Smith-Purcell effect

    Science.gov (United States)

    Talebi, Nahid

    2016-12-01

    Slow swift electrons with low self-inertia interact differently with matter and light in comparison with their relativistic counterparts: they are easily recoiled, reflected, and also diffracted form optical gratings and nanostructures. As a consequence, they can be also better manipulated into the desired shape. For example, they get bunched quite fast in interaction with acceleration gratings in presence of an external electromagnetic radiation, a phenomenon which can be desirable in development of superradiant coherent light sources. Here, I examine the spatiotemporal behavior of pulsed electron wave packets at low energies interacting with pulsed light and optical gratings, using a quantum-mechanical self-consistent numerical toolbox which is introduced here. It will be shown that electron pulses are accelerated very fast in interaction with the near-field of the grating, demanding that a synchronicity condition is met. To prevent the electrons to be transversely deflected from the grating a symmetric double-grating configuration is necessary. It is found that even in this configuration, diffraction due to the interaction of the electron with the standing-wave light inside the gap between the gratings, is a source of defocusing. Moreover, the longitudinal broadening of the electron pulse directly affects the final shape of the electron wave packet due to the occurrence of multiple electron-photon scatterings. These investigations pave the way towards the design of more efficient electron-driven photon sources and accelerators.

  9. The stereo-dynamics of collisional autoionization of ammonia by helium and neon metastable excited atoms through molecular beam experiments

    Energy Technology Data Exchange (ETDEWEB)

    Falcinelli, Stefano, E-mail: stefano.falcinelli@unipg.it; Vecchiocattivi, Franco [Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125 Perugia (Italy); Bartocci, Alessio; Cavalli, Simonetta; Pirani, Fernando [Department of Chemistry, Biology, and Biotechnology, University of Perugia, Via Elce di sotto 8, 06123 Perugia (Italy)

    2015-10-28

    A combined analysis of both new (energy spectra of emitted electrons) and previously published (ionization cross sections) experimental data, measured under the same conditions and concerning electronically excited lighter noble gas –NH{sub 3} collisional autoionization processes, is carried out. Such an analysis, performed by exploiting a formulation of the full potential energy surface both in the real and imaginary parts, provides direct information on energetics, structure, and lifetime of the intermediate collision complex over all the configuration space. The marked anisotropy in the attraction of the real part, driving the approach of reagents, and the selective role of the imaginary component, associated to the charge transfer coupling between entrance and exit channels, suggests that reactive events occur almost exclusively in the molecular hemisphere containing the nitrogen lone pair. Crucial details on the stereo-dynamics of elementary collisional autoionization processes are then obtained, in which the open shell nature of the disclosed ionic core of metastable atom plays a crucial role. The same analysis also suggests that the strength of the attraction and the anisotropy of the interaction increases regularly along the series Ne{sup *}({sup 3}P), He{sup *}({sup 3}S), He{sup *}({sup 1}S)–NH{sub 3}. These findings can be ascribed to the strong rise of the metastable atom electronic polarizability (deformability) along the series. The obtained results can stimulate state of the art ab initio calculations focused on specific features of the transition state (energetics, structure, lifetime, etc.) which can be crucial for a further improvement of the adopted treatment and to better understand the nature of the leading interaction components which are the same responsible for the formation of the intermolecular halogen and hydrogen bond.

  10. The stereo-dynamics of collisional autoionization of ammonia by helium and neon metastable excited atoms through molecular beam experiments.

    Science.gov (United States)

    Falcinelli, Stefano; Bartocci, Alessio; Cavalli, Simonetta; Pirani, Fernando; Vecchiocattivi, Franco

    2015-10-28

    A combined analysis of both new (energy spectra of emitted electrons) and previously published (ionization cross sections) experimental data, measured under the same conditions and concerning electronically excited lighter noble gas -NH3 collisional autoionization processes, is carried out. Such an analysis, performed by exploiting a formulation of the full potential energy surface both in the real and imaginary parts, provides direct information on energetics, structure, and lifetime of the intermediate collision complex over all the configuration space. The marked anisotropy in the attraction of the real part, driving the approach of reagents, and the selective role of the imaginary component, associated to the charge transfer coupling between entrance and exit channels, suggests that reactive events occur almost exclusively in the molecular hemisphere containing the nitrogen lone pair. Crucial details on the stereo-dynamics of elementary collisional autoionization processes are then obtained, in which the open shell nature of the disclosed ionic core of metastable atom plays a crucial role. The same analysis also suggests that the strength of the attraction and the anisotropy of the interaction increases regularly along the series Ne*((3)P), He*((3)S), He*((1)S)-NH3. These findings can be ascribed to the strong rise of the metastable atom electronic polarizability (deformability) along the series. The obtained results can stimulate state of the art ab initio calculations focused on specific features of the transition state (energetics, structure, lifetime, etc.) which can be crucial for a further improvement of the adopted treatment and to better understand the nature of the leading interaction components which are the same responsible for the formation of the intermolecular halogen and hydrogen bond.

  11. A comparison of weak-turbulence and PIC simulations of weak electron-beam plasma interaction

    CERN Document Server

    Ratcliffe, Heather; Rozenan, Mohammed B Che; Nakariakov, Valery

    2014-01-01

    Quasilinear theory has long been used to treat the problem of a weak electron beam interacting with plasma and generating Langmuir waves. Its extension to weak-turbulence theory treats resonant interactions of these Langmuir waves with other plasma wave modes, in particular ion-sound waves. These are strongly damped in plasma of equal ion and electron temperatures, as sometimes seen in, for example, the solar corona and wind. Weak turbulence theory is derived in the weak damping limit, with a term describing ion-sound wave damping then added. In this paper we use the EPOCH particle-in-cell code to numerically test weak turbulence theory for a range of electron-ion temperature ratios. We find that in the cold ion limit the results agree well, but increasing ion temperature the three-wave resonance becomes broadened in proportion to the ion-sound wave damping rate. This may be important in, for example, the theory of solar radio bursts, where the spectrum of Langmuir waves is critical. Additionally we establish...

  12. Digital video analysis of health professionals' interactions with an electronic whiteboard

    DEFF Research Database (Denmark)

    Rasmussen, Rasmus; Kushniruk, Andre

    2013-01-01

    As hospital departments continue to introduce electronic whiteboards in real clinical settings a range of human factor issues have emerged and it has become clear that there is a need for improved methods for designing and testing these systems. In this study, we employed a longitudinal and natur......As hospital departments continue to introduce electronic whiteboards in real clinical settings a range of human factor issues have emerged and it has become clear that there is a need for improved methods for designing and testing these systems. In this study, we employed a longitudinal...... and naturalistic method in the usability evaluation of an electronic whiteboard system. The goal of the evaluation was to explore the extent to which usability issues experienced by users change as they gain more experience with the system. In addition, the paper explores the use of a new approach to collection...... and analysis of continuous digital video recordings of naturalistic "live" user interactions. The method developed and employed in the study included recording the users' interactions with system during actual use using screen-capturing software and analyzing these recordings for usability issues...

  13. Accessing electronic and vibronic quanta and their coherent interactions in atomically precise nanostructures

    Science.gov (United States)

    Zeltzer, Gabriel

    In condensed matter systems the spatial limit is given by the fundamental atomic and molecular interactions. Controlling matter at these length scales hold promise in both fundamental scientific research as well as applications in nanotechnology and related fields such as electronics, biochemistry and medicine. Atomic and molecular manipulation on surfaces has opened a new realm of possibilities where materials can be engineered at the spatial limit and artificial structures can be constructed with a bottom-up approach, one building block at a time. This thesis describes nanostructures assembled from CO molecules on Cu(111) using a custom-built low-temperature ultra-high vacuum (UHV) scanning tunneling microscope (STM). The design and performance of the atom-manipulation apparatus that has enabled these experiments is presented. The control of electronic and vibronic states is demonstrated in several coherent quantum geometries and interactions between these two degrees of freedom are investigated. This work has revealed a virtual vibron process where non-local vibrons are synthesized and focused using a two-dimensional electron gas as a propagation medium and molecular oscillators as a source. Analysis of higher order harmonic modes of quartz tuning fork sensors is presented in the context of high frequency optical homodyne interferometric detection of subnanometer oscillatory motion. Further developments which could expand upon the work presented herein, in which STM may be combined with quantum force sensing through the use of quartz tuning forks, are suggested.

  14. The importance of the on-site electron-electron interaction for the magnetic coupling in the zigzag spin-chain compound In2VO5

    KAUST Repository

    Wang, Hao

    2010-09-27

    We present first-principles electronic structure calculations for the zigzag spin-chain compound In2VO5 using the generalized gradient approximation both with and without inclusion of an on-site Coulomb interaction. It has been proposed that In2VO5 is characterized by itinerant V 3d electrons at high temperature and localized electrons at low temperature. Consequently, it is to be expected that electronic correlations play an important role for the magnetic transition from ferromagnetic to antiferromagnetic exchange around 120 K. In this context, we study the electronic and magnetic properties of a set of possible spin configurations. Our calculations show that inclusion of an on-site Coulomb interaction in fact changes the ground state from ferromagnetic to antiferromagnetic. © 2010 IOP Publishing Ltd.

  15. Universal increase in the superconducting critical temperature of two-dimensional semiconductors at low doping by the electron-electron interaction.

    Science.gov (United States)

    Calandra, Matteo; Zoccante, Paolo; Mauri, Francesco

    2015-02-20

    In two-dimensional multivalley semiconductors, at low doping, even a moderate electron-electron interaction enhances the response to any perturbation inducing a valley polarization. If the valley polarization is due to the electron-phonon coupling, the electron-electron interaction results in an enhancement of the superconducting critical temperature. By performing first-principles calculations beyond density functional theory, we prove that this effect accounts for the unconventional doping dependence of the superconducting transition temperature (T(c)) and of the magnetic susceptibility measured in Li(x)ZrNCI. Finally, we discuss what are the conditions for a maximal T(c) enhancement in weakly doped two-dimensional semiconductors.

  16. Just enough reality: a kinder gentler approach to stereo

    Science.gov (United States)

    Siegel, Mel

    1999-08-01

    We demonstrate that the binocular perspective disparity generated by an interocular separation that is only a few percent of the nominal 65 mm human interocular separation is still enough to stimulate depth perception. This perception, which we call microstereopsis, has a 'kinder gentler' character than the stark and stressful stimulus presented by geometrically correct virtual reality displays. Microstereopsis stimulates 'just enough reality:' enough to resolve the depth ambiguity in flat images, but not so much reality that it hurts. We observe that whereas crosstalk between left and right image channels is normally perceived as ghosting, with microstereopsis it is perceived as blur in the foreground and background. Since ghosting is objectionable, whereas blur that looks like depth-of-focus in not objectionable, this relaxes the requirement for a high contrast ratio between on and off states of the stereo view multiplexer. This relaxation in turn suggest possibilities for zoneless autostereoscopic displays. We propose a realization based on an electronically toggled louvre filter using suspended particle display technology.

  17. Small solar wind transients: Stereo-A observations in 2009

    Energy Technology Data Exchange (ETDEWEB)

    Yu, W.; Farrugia, C. J.; Galvin, A. B.; Simunac, K. D. C.; Popecki, M. A.; Lugaz, N. [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Kilpua, E. K. J. [Dept. of Physics, Division of Geophysics and Astronomy, University of Helsinki (Finland); Moestl, C. [Institute of Physics, University of Graz, 8010 Graz, Austria and Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Luhmann, J. G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Opitz, A.; Sauvaud, J.-A. [Institut de Recherche en Astrophysique et Planetologie (CNRS-UPS), Universite de Toulouse, F-31038, Toulouse (France)

    2013-06-13

    Year 2009 was the last year of a long and pronounced solar activity minimum. In this year the solar wind in the inner heliosphere was for 90% of the time slow (< 450 km s{sup -1}) and with a weaker magnetic field strength compared to the previous solar minimum 1995-1996. We choose this year to present the results of a systematic search for small solar wind transients (STs) observed by the STEREO-Ahead (ST-A) probe. The data are from the PLASTIC and IMPACT instrument suites. By 'small' we mean a duration from {approx}1 to 12 hours. The parameters we search for to identify STs are (i) the total field strength, (ii) the rotation of the magnetic field vector, (iii) its smoothness, (iv) proton temperature, (v) proton beta, and (vi) Alfven Mach number. We find 45 examples. The STs have an average duration of {approx}4 hours. Ensemble averages of key quantities are: (i) maximum B = 7.01 nT; (ii) proton {beta}= 0.18; (iii) proton thermal speed = 20.8 km s{sup -1}; and (iv) Alfven Mach number = 6.13. No distinctive feature is found in the pitch angle distributions of suprathermal electrons. Our statistical results are compared with those of STs observed near Earth by Wind during 2009.

  18. Effective atomic numbers, electron densities and kinetic energy released in matter of vitamins for photon interaction

    Science.gov (United States)

    Shantappa, A.; Hanagodimath, S. M.

    2014-01-01

    Effective atomic numbers, electron densities of some vitamins (Retinol, Riboflavin, Niacin, Biotin, Folic acid, Cobalamin, Phylloquinone and Flavonoids) composed of C, H, O, N, Co, P and S have been calculated for total and partial photon interactions by the direct method for energy range 1 keV-100 GeV by using WinXCOM and kinetic energy released in matter (Kerma) relative to air is calculated in energy range of 1 keV-20 MeV. Change in effective atomic number and electron density with energy is calculated for all photon interactions. Variation of photon mass attenuation coefficients with energy are shown graphically only for total photon interaction. It is observed that change in mass attenuation coefficient with composition of different chemicals is very large below 100 keV and moderate between 100 keV and 10 MeV and negligible above 10 MeV. Behaviour of vitamins is almost indistinguishable except biotin and cobalamin because of large range of atomic numbers from 1(H) to 16 (S) and 1(H) to 27(Co) respectively. K a value shows a peak due to the photoelectric effect around K-absorption edge of high- Z constituent of compound for biotin and cobalamin.

  19. MISR Level 2 TOA/Cloud Stereo parameters V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This is the Level 2 TOA/Cloud Stereo Product. It contains the Stereoscopically Derived Cloud Mask (SDCM), cloud winds, Reflecting Level Reference Altitude (RLRA),...

  20. Alternative confidence measure for local matching stereo algorithms

    CSIR Research Space (South Africa)

    Ndhlovu, T

    2009-11-01

    Full Text Available The authors present a confidence measure applied to individual disparity estimates in local matching stereo correspondence algorithms. It aims at identifying textureless areas, where most local matching algorithms fail. The confidence measure works...

  1. Teater (stereo)tüüpide loojana / Anneli Saro

    Index Scriptorium Estoniae

    Saro, Anneli, 1968-

    2006-01-01

    Tutvustatakse 27. märtsil Tartu Ülikooli ajaloomuuseumis toimuva Eesti Teatriuurijate Ühenduse ning TÜ teatriteaduse ja kirjandusteooria õppetooli korraldatud konverentsi "Teater sotsiaalsete ja kultuuriliste (stereo)tüüpide loojana" teemasid

  2. Method of stereo matching based on genetic algorithm

    Science.gov (United States)

    Lu, Chaohui; An, Ping; Zhang, Zhaoyang

    2003-09-01

    A new stereo matching scheme based on image edge and genetic algorithm (GA) is presented to improve the conventional stereo matching method in this paper. In order to extract robust edge feature for stereo matching, infinite symmetric exponential filter (ISEF) is firstly applied to remove the noise of image, and nonlinear Laplace operator together with local variance of intensity are then used to detect edges. Apart from the detected edge, the polarity of edge pixels is also obtained. As an efficient search method, genetic algorithm is applied to find the best matching pair. For this purpose, some new ideas are developed for applying genetic algorithm to stereo matching. Experimental results show that the proposed methods are effective and can obtain good results.

  3. Clustered features for use in stereo vision SLAM

    CSIR Research Space (South Africa)

    Joubert, D

    2010-07-01

    Full Text Available SLAM, or simultaneous localization and mapping, is a key component in the development of truly independent robots. Vision-based SLAM utilising stereo vision is a promising approach to SLAM but it is computationally expensive and difficult...

  4. Application of Stereo Vision to the Reconnection Scaling Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Klarenbeek, Johnny [Los Alamos National Laboratory; Sears, Jason A. [Los Alamos National Laboratory; Gao, Kevin W. [Los Alamos National Laboratory; Intrator, Thomas P. [Los Alamos National Laboratory; Weber, Thomas [Los Alamos National Laboratory

    2012-08-14

    The measurement and simulation of the three-dimensional structure of magnetic reconnection in astrophysical and lab plasmas is a challenging problem. At Los Alamos National Laboratory we use the Reconnection Scaling Experiment (RSX) to model 3D magnetohydrodynamic (MHD) relaxation of plasma filled tubes. These magnetic flux tubes are called flux ropes. In RSX, the 3D structure of the flux ropes is explored with insertable probes. Stereo triangulation can be used to compute the 3D position of a probe from point correspondences in images from two calibrated cameras. While common applications of stereo triangulation include 3D scene reconstruction and robotics navigation, we will investigate the novel application of stereo triangulation in plasma physics to aid reconstruction of 3D data for RSX plasmas. Several challenges will be explored and addressed, such as minimizing 3D reconstruction errors in stereo camera systems and dealing with point correspondence problems.

  5. Infrared stereo calibration for unmanned ground vehicle navigation

    Science.gov (United States)

    Harguess, Josh; Strange, Shawn

    2014-06-01

    The problem of calibrating two color cameras as a stereo pair has been heavily researched and many off-the-shelf software packages, such as Robot Operating System and OpenCV, include calibration routines that work in most cases. However, the problem of calibrating two infrared (IR) cameras for the purposes of sensor fusion and point could generation is relatively new and many challenges exist. We present a comparison of color camera and IR camera stereo calibration using data from an unmanned ground vehicle. There are two main challenges in IR stereo calibration; the calibration board (material, design, etc.) and the accuracy of calibration pattern detection. We present our analysis of these challenges along with our IR stereo calibration methodology. Finally, we present our results both visually and analytically with computed reprojection errors.

  6. Rapid matching of stereo vision based on fringe projection profilometry

    Science.gov (United States)

    Zhang, Ruihua; Xiao, Yi; Cao, Jian; Guo, Hongwei

    2016-09-01

    As the most important core part of stereo vision, there are still many problems to solve in stereo matching technology. For smooth surfaces on which feature points are not easy to extract, this paper adds a projector into stereo vision measurement system based on fringe projection techniques, according to the corresponding point phases which extracted from the left and right camera images are the same, to realize rapid matching of stereo vision. And the mathematical model of measurement system is established and the three-dimensional (3D) surface of the measured object is reconstructed. This measurement method can not only broaden application fields of optical 3D measurement technology, and enrich knowledge achievements in the field of optical 3D measurement, but also provide potential possibility for the commercialized measurement system in practical projects, which has very important scientific research significance and economic value.

  7. Direct stereo radargrammetric processing using massively parallel processing

    Science.gov (United States)

    Balz, Timo; Zhang, Lu; Liao, Mingsheng

    2013-05-01

    Synthetic Aperture Radar (SAR) offers many ways to reconstruct digital surface models (DSMs). The two most commonly used methods are SAR interferometry (InSAR) and stereo radargrammetry. Stereo radargrammetry is a very stable and reliable process and is far less affected by temporal decorrelation compared with InSAR. It is therefore often used for DSM generation in heavily vegetated areas. However, stereo radargrammetry often produces rather noisy DSMs, sometimes containing large outliers. In this manuscript, we present a new approach for stereo radargrammetric processing, where the homologous points between the images are found by geocoding large amount of points. This offers a very flexible approach, allowing the simultaneous processing of multiple images and of cross-heading image pairs. Our approach relies on a good initial geocoding accuracy of the data and on very fast processing using a massively parallel implementation. The approach is demonstrated using TerraSAR-X images from Mount Song, China, and from Trento, Italy.

  8. Local algorithms on dense two-frame stereo matching

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; LI Xuemei; WANG Shuozhen

    2012-01-01

    Stereo matching is a fundamental and crucial problem in computer vision. In the last decades, many researchers have been working on it and made great progress. Generally stereo algorithms can be classified into local methods and global methods. In this paper, the challenges of stereo matching are first introduced, and then we focus on local approaches which have simpler structures and higher efficiency than global ones. Local algorithms generally perform four steps: cost computation, cost aggregation, disparity computation and disparity refinement. Every step is deeply investigated, and most work focuses on cost aggregation. We studied most of the classical local methods and divide them into several classes. The classification well illustrates the development history of local stereo correspondence and shows the essence of local matching along with its important and difficult points. At the end we give the future development trend of local methods.

  9. Teater (stereo)tüüpide loojana / Anneli Saro

    Index Scriptorium Estoniae

    Saro, Anneli, 1968-

    2006-01-01

    Tutvustatakse 27. märtsil Tartu Ülikooli ajaloomuuseumis toimuva Eesti Teatriuurijate Ühenduse ning TÜ teatriteaduse ja kirjandusteooria õppetooli korraldatud konverentsi "Teater sotsiaalsete ja kultuuriliste (stereo)tüüpide loojana" teemasid

  10. Ultrafast quenching of electron-boson interaction and superconducting gap in a cuprate superconductor.

    Science.gov (United States)

    Zhang, Wentao; Hwang, Choongyu; Smallwood, Christopher L; Miller, Tristan L; Affeldt, Gregory; Kurashima, Koshi; Jozwiak, Chris; Eisaki, Hiroshi; Adachi, Tadashi; Koike, Yoji; Lee, Dung-Hai; Lanzara, Alessandra

    2014-01-01

    Ultrafast spectroscopy is an emerging technique with great promise in the study of quantum materials, as it makes it possible to track similarities and correlations that are not evident near equilibrium. Thus far, however, the way in which these processes modify the electron self-energy--a fundamental quantity describing many-body interactions in a material--has been little discussed. Here we use time- and angle-resolved photoemission to directly measure the ultrafast response of self-energy to near-infrared photoexcitation in high-temperature cuprate superconductor. Below the critical temperature of the superconductor, ultrafast excitations trigger a synchronous decrease of electron self-energy and superconducting gap, culminating in a saturation in the weakening of electron-boson coupling when the superconducting gap is fully quenched. In contrast, electron-boson coupling is unresponsive to ultrafast excitations above the critical temperature of the superconductor and in the metallic state of a related material. These findings open a new pathway for studying transient self-energy and correlation effects in solids.

  11. Effects of electron-phonon interaction on thermal and electrical transport through molecular nano-conductors

    Energy Technology Data Exchange (ETDEWEB)

    Lü, Jing-Tao, E-mail: jtlu@hust.edu.cn [School of Physics, Huazhong University of Science and Technology, 430074 Wuhan (China); Zhou, Hangbo [Department of Physics and Center for Computational Science and Engineering, National University of Singapore, 117551 Singapore (Singapore); NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 117456 Singapore (Singapore); Jiang, Jin-Wu [Shanghai Institute of Applied Mathematics and Mechanics, Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai University, 200072 Shanghai (China); Wang, Jian-Sheng [Department of Physics and Center for Computational Science and Engineering, National University of Singapore, 117551 Singapore (Singapore)

    2015-05-15

    The topic of this review is the effects of electron-phonon interaction (EPI) on the transport properties of molecular nano-conductors. A nano-conductor connects to two electron leads and two phonon leads, possibly at different temperatures or chemical potentials. The EPI appears only in the nano-conductor. We focus on its effects on charge and energy transport. We introduce three approaches. For weak EPI, we use the nonequilibrium Green’s function method to treat it perturbatively. We derive the expressions for the charge and heat currents. For weak system-lead couplings, we use the quantum master equation approach. In both cases, we use a simple single level model to study the effects of EPI on the system’s thermoelectric transport properties. It is also interesting to look at the effect of currents on the dynamics of the phonon system. For this, we derive a semi-classical generalized Langevin equation to describe the nano-conductor’s atomic dynamics, taking the nonequilibrium electron system, as well as the rest of the atomic degrees of freedom as effective baths. We show simple applications of this approach to the problem of energy transfer between electrons and phonons.

  12. Effects of electron-phonon interaction on thermal and electrical transport through molecular nano-conductors

    Directory of Open Access Journals (Sweden)

    Jing-Tao Lü

    2015-05-01

    Full Text Available The topic of this review is the effects of electron-phonon interaction (EPI on the transport properties of molecular nano-conductors. A nano-conductor connects to two electron leads and two phonon leads, possibly at different temperatures or chemical potentials. The EPI appears only in the nano-conductor. We focus on its effects on charge and energy transport. We introduce three approaches. For weak EPI, we use the nonequilibrium Green’s function method to treat it perturbatively. We derive the expressions for the charge and heat currents. For weak system-lead couplings, we use the quantum master equation approach. In both cases, we use a simple single level model to study the effects of EPI on the system’s thermoelectric transport properties. It is also interesting to look at the effect of currents on the dynamics of the phonon system. For this, we derive a semi-classical generalized Langevin equation to describe the nano-conductor’s atomic dynamics, taking the nonequilibrium electron system, as well as the rest of the atomic degrees of freedom as effective baths. We show simple applications of this approach to the problem of energy transfer between electrons and phonons.

  13. Light Sea Fermions in Electron-Proton and Muon-Proton Interactions

    CERN Document Server

    Jentschura, U D

    2014-01-01

    The proton radius conundrum [R. Pohl et al., Nature vol.466, p.213 (2010) and A. Antognini et al., Science vol.339, p.417 (2013)] highlights the need to revisit any conceivable sources of electron-muon nonuniversality in lepton-proton interactions within the Standard Model. Superficially, a number of perturbative processes could appear to lead to such a nonunversality. One of these is a coupling of the scattered electron into an electronic as opposed to a muonic vacuum polarization loop in the photon exchange of two valence quarks, which is present only for electron projectiles as opposed to muon projectiles. However, we can show that this effect actually is part of the radiative correction to the proton's polarizability contribution to the Lamb shift, equivalent to a radiative correction to double scattering. We conclude that any conceivable genuine nonuniversality must be connected with a nonperturbative feature of the proton's structure, e.g., with the possible presence of light sea fermions as constituent...

  14. Electronic interactions between "pea" and "pod": the case of oligothiophenes encapsulated in carbon nanotubes.

    Science.gov (United States)

    Gao, Jia; Blondeau, Pascal; Salice, Patrizio; Menna, Enzo; Bártová, Barbora; Hébert, Cécile; Leschner, Jens; Kaiser, Ute; Milko, Matus; Ambrosch-Draxl, Claudia; Loi, Maria Antonietta

    2011-07-04

    One of the most challenging strategies to achieve tunable nanophotonic devices is to build robust nanohybrids with variable emission in the visible spectral range, while keeping the merits of pristine single-walled carbon nanotubes (SWNTs). This goal is realized by filling SWNTs ("pods") with a series of oligothiophene molecules ("peas"). The physical properties of these peapods are depicted by using aberration-corrected high-resolution transmission electron microscopy, Raman spectroscopy, and other optical methods including steady-state and time-resolved measurements. Visible photoluminescence with quantum yields up to 30% is observed for all the hybrids. The underlying electronic structure is investigated by density functional theory calculations for a series of peapods with different molecular lengths and tube diameters, which demonstrate that van der Waals interactions are the bonding mechanism between the encapsulated molecule and the tube.

  15. Configuration interaction with Kohn Sham orbitals and their relation to excited electronic states

    Science.gov (United States)

    Bouř, Petr

    2001-09-01

    Kohn-Sham (KS) orbitals in CH 2, formaldehyde and acetone molecules were used as reference states for configuration interaction (CI) instead of the usual Hartree-Fock (HF) orbitals. A little difference in overall accuracy of electronic excitation energies was found between these schemes. However, analysis of the wave functions indicated that Slater determinant with the KS orbitals is more suitable for construction of the electronic states. Typically, the main expansion coefficients for the CI/KS procedure were closer to unity than those for HF. The difference was most pronounced for the lowest-energy transitions, while the two methods provided more comparable results for the higher-energy states. Similar behaviour of singlet and triplet states was observed. The results justify the common practice of using the KS determinant as a wave function, for example in sum-over-states theories.

  16. Periodically driven interacting electrons in one dimension: Many-body Floquet approach

    Science.gov (United States)

    Puviani, M.; Manghi, F.

    2016-10-01

    We propose a method to study the time evolution of correlated electrons driven by a harmonic perturbation. Combining Floquet formalism to include the time-dependent field and cluster perturbation theory to solve the many-body problem in the presence of short-range correlations, we treat the electron double dressing, by photons and by e -e interactions, on the same footing. We apply the method to an extended Hubbard chain at half occupation, and we show that in the regime of small field frequency and for given values of field strength, the zero-mode Floquet band is no longer gapped and the system recovers a metallic state. Our results are indicative of an omnipresent mechanism for insulator-to-metal transitions in one-dimensional systems.

  17. Improved Ligand-Field Theory with Effect of Electron-Phonon Interaction

    Institute of Scientific and Technical Information of China (English)

    MA Dong-Ping; CHEN Ju-Rong

    2005-01-01

    Traditional ligand-field theory has to be improved by taking into account both "pure electronic" contribution and electron-phonon interaction one (including lattice-vibrational relaxation energy). By means of improved ligand-field theory, R1, R2, R'3, R'2, and R'1 lines, U band, ground-state zero-field-splitting (GSZFS), and ground-state g factors of ruby and/or GSGG: Cr3+ as well as thermal shifts of GSZFS, R1 line and R2 line of ruby have been calculated.The results are in very good agreement with the experimental data. Moreover, it is found that the value of cubic-field parameter given by traditional ligand-field theory is inappropriately large. For thermal shifts of GSZFS, R1 line and R2 line of ruby, several conclusions have also been obtained.

  18. Surprising electronic structure of the BeH- dimer: a full-configuration-interaction study.

    Science.gov (United States)

    Verdicchio, Marco; Bendazzoli, Gian Luigi; Evangelisti, Stefano; Leininger, Thierry

    2013-01-10

    The electronic structure of the beryllium hydride anion, BeH(-), was investigated at valence full-configuration-interaction (FCI) level, using large cc-pV6Z basis sets. It appears that there is a deep change of the wave function nature as a function of the internuclear distance: the ion structure goes from a weakly bonded Be···H(-) complex, at long distance, to a rather strongly bonded system (more than 2 eV) at short distance, having a (:Be-H)(-) Lewis structure. In this case, it is the beryllium atom that formally bears the negative charge, a surprising result in view of the fact that it is the hydrogen atom that has a larger electronegativity. Even more surprisingly, at very short distances the average position of the total electronic charge is close to the beryllium atom but on the opposite side with respect to the hydrogen position.

  19. On the relationship between bond-length alternation and many-electron self-interaction error

    Science.gov (United States)

    Körzdörfer, Thomas; Parrish, Robert M.; Sears, John S.; Sherrill, C. David; Brédas, Jean-Luc

    2012-09-01

    Predicting accurate bond-length alternations (BLAs) in long conjugated molecular chains has been a major challenge for electronic-structure theory for many decades. While Hartree-Fock (HF) overestimates BLA significantly, second-order perturbation theory and commonly used density functional theory (DFT) approaches typically underestimate it. Here, we discuss how this failure is related to the many-electron self-interaction error (MSIE), which is inherent to both HF and DFT approaches. We use tuned long-range corrected hybrids to minimize the MSIE for a series of polyenes. The key result is that the minimization of the MSIE alone does not yield accurate BLAs. On the other hand, if the range-separation parameter is tuned to yield accurate BLAs, we obtain a significant MSIE that grows with chain length. Our findings demonstrate that reducing the MSIE is one but not the only important aspect necessary to obtain accurate BLAs from density functional theory.

  20. FEATURES OF TECHNOLOGIES CREATE INTERACTIVE ELECTRONIC DOCUMENT FOR SUPPORT OF LABORATORY PRACTICAL PHYSICS

    Directory of Open Access Journals (Sweden)

    Mykola A. Meleshko

    2014-02-01

    Full Text Available The article discusses the content of the «flash-book» construct, defining its properties and possible components. There are presented some examples of components programming steps of “authoring flash – book”, considered the possibility of using such an electronic document to optimize the learning process at the Technical University in the performance of laboratory training on general physics. The technique of its using to provide individualized approach to learning and the use of various experimental base from classical to digital equipment laboratories is proposed. It was carried out the analysis of ways to improve such interactive electronic document for the development of information technology competence of engineering students.