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Sample records for 3-body distorted wave

  1. CMB μ distortion from primordial gravitational waves

    SciTech Connect

    Ota, Atsuhisa; Yamaguchi, Masahide; Takahashi, Tomo; Tashiro, Hiroyuki E-mail: tomot@cc.saga-u.ac.jp E-mail: gucci@phys.titech.ac.jp

    2014-10-01

    We propose a new mechanism of generating the μ distortion in cosmic microwave background (CMB) originated from primordial gravitational waves. Such μ distortion is generated by the damping of the temperature anisotropies through the Thomson scattering, even on scales larger than that of Silk damping. This mechanism is in sharp contrast with that from the primordial curvature (scalar) perturbations, in which the temperature anisotropies mainly decay by Silk damping effects. We estimate the size of the μ distortion from the new mechanism, which can be used to constrain the amplitude of primordial gravitational waves on smaller scales independently from the CMB anisotropies, giving more wide-range constraint on their spectral index by combining the amplitude from the CMB anisotropies.

  2. Optical distortion in the field of a lithotripter shock wave

    NASA Astrophysics Data System (ADS)

    Carnell, M. T.; Emmony, D. C.

    1995-10-01

    The schlieren observation of cavitation phenomena produced in the tail of a lithotripter shock wave has indicated the presence of some interesting features. The images produced appear to indicate that cavitation transients in the field of a shock wave propagate nonsymmetrically; this is not the case. The apparent lack of symmetry exhibited by the primary cavitation transients is due to a complex optical lensing effect, which is brought about by the change in refractive index associated with the pressure profile of the shock wave. Objects seen through or immersed in the shock-wave field of an electromagnetic acoustic transducer, such as cavitation, appear highly distorted because of the strong positive and negative lensing effects of the compression and rarefaction cycles of the shock wave. A modification of the schlieren technique called the scale method has been used to model the distortion introduced by the shock wave and consequently explain the cavitation distortion. The technique has also been used to quantitatively analyze and partially reconstruct the lithotripter shock wave. The combination of schlieren and scale imaging gives more information about the refractive index field and therefore the shock-wave structure itself.

  3. Optical beam distortions induced by a shock wave.

    PubMed

    Banakh, V A; Sukharev, A A; Falits, A V

    2015-03-10

    The mean intensity and the displacement from the initially given propagation direction of the optical beam passed through the shock wave have been calculated. It has been shown that the spatial inhomogeneity of the refractive index of air caused by the shock wave arising in supersonic flow flowing a conical body can cause the focusing of the beam and strong anisotropic distortions of the intensity distribution in its cross section. The angular displacement of the optical beam from the initially given propagation direction owing to the shock wave depends only on the height above the Earth's surface at which the shock wave is formed. As the height increases, the influence of the shock wave on the optical beam propagating through it decreases.

  4. Effect of distorted illumination waves on coherent diffraction microscopy

    NASA Astrophysics Data System (ADS)

    Kohmura, Yoshiki; Nishino, Yoshinori; Ishikawa, Tetsuya; Miao, Jianwei

    2005-12-01

    Coherent diffraction microscopy requires a well-defined illumination wave such as a plane wave on a specimen. Experimentally, a small pinhole or a focused beam is often used to reduce the illumination area but they unavoidably distort the waves. The distortion of the illumination wave causes artifacts in the phase retrieval of oversampled diffraction patterns. Using computer simulations, we searched for the conditions where strong artifacts arise by changing the Fresnel number, pinhole size, alignment error and photon statistics. The experimental setup with Fresnel number of around 1 and smaller than 1 realized a small reconstruction error when the pinhole radius is larger than a few times the specimen size. These conditions are suitable for the rotation of specimens for the three-dimensional (3D) observations. Such investigation will have an impact in the design of coherent diffraction microscopes for the 3D characterization of nanoscale materials and biological systems using the third generation synchrotron radiation and future x-ray free-electron lasers.

  5. A distorted wave impulse approach for atom--diatom collisions

    SciTech Connect

    Dothe, H. ); Sharma, R.D. , Hanscom Air Force Base, Massachusetts 01731-5000 )

    1993-03-15

    A formalism is derived to include the effects of the long-range attractive part of the interaction potential in the calculation of atom--diatom collision cross sections using the impulse approach (IA). These calculations have, until now, assumed the atom--diatom potential given by a sum of two atom--atom interactions, consequently yielding a poor representation of the long-range attractive part. In the distorted wave impulse approach (DWIA) the long-range attractive part, located at the center of mass of the diatom, is a spherically symmetric potential which distorts'' the incoming and outgoing waves. The DWIA formalism is used to calculate differential cross sections for the rotationally inelastic process Li[sup +]+N[sub 2]([ital v]=0, [ital j]=2)[r arrow]Li[sup +]+N[sub 2]([ital v][prime]=0, [ital j][prime]), as a function of the final rotational level [ital j][prime], at a relative kinetic energy of 4.23 eV and center of mass scattering angles of 49.2[degree] and 37.1[degree]. It is shown that differential cross sections calculated using the DWIA formalism are in much better agreement with experimentally measured ones than IA differential cross sections using atom--atom interactions expressed by either hard-core, or exponential repulsive, functions.

  6. Second order distorted wave calculations for electron impact ionization processes

    NASA Astrophysics Data System (ADS)

    Chen, Zhangjin

    Electron impact ionization of atoms provides a fundamental test of the current understanding of atomic structure as well as our understanding of the three body problem. Triple differential cross sections (TDCS), measured in the coincidence experiment, provide the most sensitive test of the theory of electron impact ionization processes. It was found two decades ago that second-order effects were crucial in explaining both the positions and magnitudes of the binary and recoil peaks in the TDCS. However, the existing theoretical calculations of second-order amplitudes typically resort to simplifying approximations, such as the closure approximation or neglecting the real part of the Green's function, to make the calculation tractable. In this work, we have developed a second-order distorted wave (DWB2) theory for atomic ionization which does not make these approximations. The DWB2 theory has been used to calculate the TDCS for electron impact ionization of hydrogen. It is found that the DWB2 results are in good agreement with absolute experimental measurements for incident energy greater than 100 eV. We have also performed DWB2 calculations for electron impact ionization of helium with the residual ion left in the n=1 and 2 states at intermediate energies in coplanar asymmetric geometry. Both the neutral and ionic distorting potentials are employed for the projectile in the final state. It has been found that the DWB2 results with the ionic distorting potential are in better agreement with experiment for the case in which the residual ion is left in the excited states. We have also performed the calculations to check the validity of the closure approximation and the simplified Green's function approximation and found that these approximations are not accurate for non-coplanar geometry and low incident energies.

  7. CMB distortions from damping of acoustic waves produced by cosmic strings

    SciTech Connect

    Tashiro, Hiroyuki; Sabancilar, Eray; Vachaspati, Tanmay E-mail: Eray.Sabancilar@asu.edu

    2013-08-01

    We study diffusion damping of acoustic waves in the photon-baryon fluid due to cosmic strings, and calculate the induced μ- and y-type spectral distortions of the cosmic microwave background. For cosmic strings with tension within current bounds, their contribution to the spectral distortions is subdominant compared to the distortions from primordial density perturbations.

  8. Digital Distortion Caused by Traveling- Wave-Tube Amplifiers Simulated

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.; Andro, Monty

    2002-01-01

    Future NASA missions demand increased data rates in satellite communications for near real-time transmission of large volumes of remote data. Increased data rates necessitate higher order digital modulation schemes and larger system bandwidth, which place stricter requirements on the allowable distortion caused by the high-power amplifier, or the traveling-wave-tube amplifier (TWTA). In particular, intersymbol interference caused by the TWTA becomes a major consideration for accurate data detection at the receiver. Experimentally investigating the effects of the physical TWTA on intersymbol interference would be prohibitively expensive, as it would require manufacturing numerous amplifiers in addition to acquiring the required digital hardware. Thus, an accurate computational model is essential to predict the effects of the TWTA on system-level performance when a communication system is being designed with adequate digital integrity for high data rates. A fully three-dimensional, time-dependent, TWT interaction model has been developed using the electromagnetic particle-in-cell code MAFIA (Solution of Maxwell's equations by the Finite-Integration-Algorithm). It comprehensively takes into account the effects of frequency-dependent AM (amplitude modulation)/AM and AM/PM (phase modulation) conversion, gain and phase ripple due to reflections, drive-induced oscillations, harmonic generation, intermodulation products, and backward waves. This physics-based TWT model can be used to give a direct description of the effects of the nonlinear TWT on the operational signal as a function of the physical device. Users can define arbitrary excitation functions so that higher order modulated digital signals can be used as input and that computations can directly correlate intersymbol interference with TWT parameters. Standard practice involves using communication-system-level software packages, such as SPW, to predict if adequate signal detection will be achieved. These models

  9. A light-curve distortion-wave analysis of eight RS Canum Venaticorum systems

    NASA Astrophysics Data System (ADS)

    Caton, D. B.

    1986-01-01

    A program of differential U,B,V photometry of 14 RS CVn systems carried out at Rosemary Hill Observatory in 1978 - 1981 is described, and an analysis of the light curves for the characteristic distortion wave for eight of the systems is presented. The V light curves of the systems are shown. Significant waves were observed in RS CVn, RZ Eri, and RW UMa. No significant waves were found in UX Com, GK Hya, AR Lac, LX Per, or TY Pyx. Unusual light curve distortions were observed in UX Com and AR Lac.

  10. Computation of the temperature distortion in the stack of a standing-wave thermoacoustic refrigerator

    NASA Astrophysics Data System (ADS)

    Marx, David; Blanc-Benon, Philippe

    2005-11-01

    The numerical computation of the flow and heat transfer in the vicinity of a stack plate in a standing wave refrigerator is performed. Temperature distortion is observed, which appears only in the stack region, even if the acoustic standing wave outside the stack is itself sinusoidal. The distortion takes place above the whole plate surface when the length of the plate is equal to or shorter than four times the particle displacement. This condition may occur at high drive ratios and is favored by plate positions close to the velocity antinode. The thermal distortion decreases the thermoacoustic heat pumping along the plate. At high drive ratios, if the length of the plate is not large enough, the thermal distortion can typically explain a difference of about 10% between the calculated heat flux and the heat flux predicted using linear theory.

  11. Finite range distorted-wave Born approximation analysis of (p,t) reactions with a realistic triton wave function

    NASA Astrophysics Data System (ADS)

    Werby, M. F.; Strayer, M. R.; Nagarajan, M. A.

    1980-06-01

    Exact finite range distorted-wave Born approximation analysis of the ground state reactions 208Pb(p,t)206Pb and 18O(p,t)16O are presented. The calculations are carried out using a realistic triton wave function comprising a spatially symmetric S and mixed symmetric S' and D states. The transfer interaction is treated consistently with the interaction used in obtaining the triton wave function. The use of a realistic wave function and transfer potential yields improved agreement between experimental and theoretical angular distributions. Calculations using the wave function of the transferred neutron pair suggest it is possible to explain both the absolute magnitude and shape of the angular distribution for these transitions. NUCLEAR REACTIONS (p,t), distorted-wave Born approximation analyses.

  12. Observation of wave packet distortion during a negative-group-velocity transmission.

    PubMed

    Ye, Dexin; Salamin, Yannick; Huangfu, Jiangtao; Qiao, Shan; Zheng, Guoan; Ran, Lixin

    2015-01-29

    In Physics, causality is a fundamental postulation arising from the second law of thermodynamics. It states that, the cause of an event precedes its effect. In the context of Electromagnetics, the relativistic causality limits the upper bound of the velocity of information, which is carried by electromagnetic wave packets, to the speed of light in free space (c). In anomalously dispersive media (ADM), it has been shown that, wave packets appear to propagate with a superluminal or even negative group velocity. However, Sommerfeld and Brillouin pointed out that the "front" of such wave packets, known as the initial point of the Sommerfeld precursor, always travels at c. In this work, we investigate the negative-group-velocity transmission of half-sine wave packets. We experimentally observe the wave front and the distortion of modulated wave packets propagating with a negative group velocity in a passive artificial ADM in microwave regime. Different from previous literature on the propagation of superluminal Gaussian packets, strongly distorted sinusoidal packets with non-superluminal wave fronts were observed. This result agrees with Brillouin's assertion, i.e., the severe distortion of seemingly superluminal wave packets makes the definition of group velocity physically meaningless in the anomalously dispersive region.

  13. Observation of Wave Packet Distortion during a Negative-Group-Velocity Transmission

    NASA Astrophysics Data System (ADS)

    Ye, Dexin; Salamin, Yannick; Huangfu, Jiangtao; Qiao, Shan; Zheng, Guoan; Ran, Lixin

    2015-01-01

    In Physics, causality is a fundamental postulation arising from the second law of thermodynamics. It states that, the cause of an event precedes its effect. In the context of Electromagnetics, the relativistic causality limits the upper bound of the velocity of information, which is carried by electromagnetic wave packets, to the speed of light in free space (c). In anomalously dispersive media (ADM), it has been shown that, wave packets appear to propagate with a superluminal or even negative group velocity. However, Sommerfeld and Brillouin pointed out that the ``front'' of such wave packets, known as the initial point of the Sommerfeld precursor, always travels at c. In this work, we investigate the negative-group-velocity transmission of half-sine wave packets. We experimentally observe the wave front and the distortion of modulated wave packets propagating with a negative group velocity in a passive artificial ADM in microwave regime. Different from previous literature on the propagation of superluminal Gaussian packets, strongly distorted sinusoidal packets with non-superluminal wave fronts were observed. This result agrees with Brillouin's assertion, i.e., the severe distortion of seemingly superluminal wave packets makes the definition of group velocity physically meaningless in the anomalously dispersive region.

  14. Correction of walk-off-induced wavefront distortion for continuous-wave laser

    NASA Astrophysics Data System (ADS)

    Zou, Hongxin; Chen, Guozhu; Wu, Yue; Shen, Yong; Liu, Qu

    2016-09-01

    We theoretically and experimentally investigate the wave front distortion in critically phase-matched continuous-wave (CW) second harmonic generation (SHG). Due to the walk-off effect in the nonlinear crystal, the generated second harmonic is extremely elliptical and quite non-Gaussian, which causes a very low matching and coupling efficiency in experiment. Cylindrical lenses and walk-off compensating crystals are adopted to correct distorted wave fronts, and obtain a good TEM00 mode efficiently. Theoretically, we simulate the correction effect of 266-nm laser generated with SHG. The experiment results accord well with the theoretical simulation and an above 80% TEM00 component is obtained for 266-nm continuous-wave laser with a 4.8°-walk-off angle in beta barium borate (BBO) crystal. Project supported by the National Natural Science Foundation of China (Grant No. 91436103) and Research Programme of National University of Defense Technology, China (Grant No. JC15-02-03).

  15. An algorithm for the calculation of the partial wave expansion of the Coulomb-distorted plane wave

    NASA Astrophysics Data System (ADS)

    Hornyak, I.; Kruppa, A. T.

    2015-12-01

    The partial wave expansion of the Coulomb-distorted plane wave is determined by the help of the complex generalized hypergeometric function 2F2(a , a ; a + l + 1 , a - l ; z) . An algorithm for the calculation of 2F2(a , a ; a + l + 1 , a - l ; z) is created and it is implemented as a FORTRAN-90 code. The code is fast and its accuracy is 14 significant decimal digits.

  16. Amplification of Reynolds number dependent processes by wave distortion. [liquid fuel combustor stability

    NASA Technical Reports Server (NTRS)

    Ventrice, M.

    1979-01-01

    The amplification of a Reynolds number dependent process by wave distortion and the possibility of applying the results to other similar Reynolds number dependent processes were investigated. The process investigated was that associated with the operation of a constant-temperature hot-wire anemometer. The application of vaporization limited combustion, the type of combustion typically associated with liquid propellant rocket engines, was studied. A series of experiments were carried out to determine the effect of wave distortion on a Reynolds number dependent process and to establish the analogy between the anemometer process and the combustion process. Parametric trends, behavior common to different chamber geometries, and stability boundaries were identified. The results indicate a high degree of similarity between the two processes and the possibility of using the anemometer system to investigate combustion instability. The nonlinear aspects of a Reynolds number dependent process appear to be the dominant mechanisms controlling instability.

  17. Correction of walk-off-induced wavefront distortion for continuous-wave laser

    NASA Astrophysics Data System (ADS)

    Zou, Hongxin; Chen, Guozhu; Wu, Yue; Shen, Yong; Liu, Qu

    2016-09-01

    We theoretically and experimentally investigate the wave front distortion in critically phase-matched continuous-wave (CW) second harmonic generation (SHG). Due to the walk-off effect in the nonlinear crystal, the generated second harmonic is extremely elliptical and quite non-Gaussian, which causes a very low matching and coupling efficiency in experiment. Cylindrical lenses and walk-off compensating crystals are adopted to correct distorted wave fronts, and obtain a good TEM00 mode efficiently. Theoretically, we simulate the correction effect of 266-nm laser generated with SHG. The experiment results accord well with the theoretical simulation and an above 80% TEM00 component is obtained for 266-nm continuous-wave laser with a 4.8°-walk-off angle in beta barium borate (BBO) crystal. Project supported by the National Natural Science Foundation of China (Grant No. 91436103) and Research Programme of National University of Defense Technology, China (Grant No. JC15-02-03).

  18. Combined approach to the Hubble Space Telescope wave-front distortion analysis

    NASA Technical Reports Server (NTRS)

    Roddier, Claude; Roddier, Francois

    1993-01-01

    Stellar images taken by the HST at various focus positions have been analyzed to estimate wave-front distortion. Rather than using a single algorithm, we found that better results were obtained by combining the advantages of various algorithms. For the planetary camera, the most accurate algorithms consistently gave a spherical aberration of -0.290-micron rms with a maximum deviation of 0.005 micron. Evidence was found that the spherical aberration is essentially produced by the primary mirror. The illumination in the telescope pupil plane was reconstructed and evidence was found for a slight camera misalignment.

  19. Combined approach to the Hubble Space Telescope wave-front distortion analysis.

    PubMed

    Roddier, C; Roddier, F

    1993-06-01

    Stellar images taken by the Hubble Space Telescope at various focus positions have been analyzed to estimate wave-front distortion. Rather than using a single algorithm, we found that better results were obtained by combining the advantages of various algorithms. For the planetary camera, the most accurate algorithms consistently gave a spherical aberration of -0.290-µm rms with a maximum deviation of 0.005 µm. Evidence was found that the spherical aberration is essentially produced by the primary mirror. The illumination in the telescope pupil plane was reconstructed and evidence was found for a slight camera misalignment.

  20. Three-wave X-ray diffraction in distorted epitaxial structures

    PubMed Central

    Kyutt, Reginald; Scheglov, Mikhail

    2013-01-01

    Three-wave diffraction has been measured for a set of GaN, AlN, AlGaN and ZnO epitaxial layers grown on c-sapphire. A Renninger scan for the primary forbidden 0001 reflection was used. For each of the three-wave combinations, θ-scan curves were measured. The intensity and angular width of both ϕ- and θ-scan three-wave peaks were analyzed. The experimental data were used to determine properties of the multiple diffraction pattern in highly distorted layers. It is shown that the FWHM of θ scans is highly sensitive to the structural perfection and strongly depends on the type of three-wave combination. The narrowest peaks are observed for multiple combinations with the largest l index of the secondary hkl reflection. An influence of the type of the dislocation structure on the θ-scan broadening was revealed. These experimental facts are interpreted by considering the scanning geometry in the reciprocal space and taking into account the disc-shaped reciprocal-lattice points. The total integrated intensities of all the three-wave combinations were determined and their ratios were found to be in only a qualitative agreement with the theory. For AlGaN layers, the presence of the nonzero 0001 reflection was revealed, in contrast to AlN and GaN films. PMID:24046489

  1. Phase Inversion: Inferring Solar Subphotospheric Flow and Other Asphericity from the Distortion of Acoustic Waves

    NASA Technical Reports Server (NTRS)

    Gough, Douglas; Merryfield, William J.; Toomre, Juri

    1998-01-01

    A method is proposed for analyzing an almost monochromatic train of waves propagating in a single direction in an inhomogeneous medium that is not otherwise changing in time. An effective phase is defined in terms of the Hilbert transform of the wave function, which is related, via the JWKB approximation, to the spatial variation of the background state against which the wave is propagating. The contaminating effect of interference between the truly monochromatic components of the train is eliminated using its propagation properties. Measurement errors, provided they are uncorrelated, are manifest as rapidly varying noise; although that noise can dominate the raw phase-processed signal, it can largely be removed by low-pass filtering. The intended purpose of the analysis is to determine the distortion of solar oscillations induced by horizontal structural variation and material flow. It should be possible to apply the method directly to sectoral modes. The horizontal phase distortion provides a measure of longitudinally averaged properties of the Sun in the vicinity of the equator, averaged also in radius down to the depth to which the modes penetrate. By combining such averages from different modes, the two-dimensional variation can be inferred by standard inversion techniques. After taking due account of horizontal refraction, it should be possible to apply the technique also to locally sectoral modes that propagate obliquely to the equator and thereby build a network of lateral averages at each radius, from which the full three-dimensional structure of the Sun can, in principle, be determined as an inverse Radon transform.

  2. Sulphur hexaflouride: low energy (e,2e) experiments and molecular three-body distorted wave theory

    NASA Astrophysics Data System (ADS)

    Nixon, Kate L.; Murray, Andrew J.; Chaluvadi, H.; Ning, C. G.; Colgan, James; Madison, Don H.

    2016-10-01

    Experimental and theoretical triple differential ionisation cross-sections (TDCSs) are presented for the highest occupied molecular orbital of sulphur hexafluoride. These measurements were performed in the low energy regime, with outgoing electron energies ranging from 5 to 40 eV in a coplanar geometry, and with energies of 10 and 20 eV in a perpendicular geometry. Complementary theoretical predictions of the TDCS were calculated using the molecular three-body distorted wave formalism. Calculations were performed using a proper average over molecular orientations as well as the orientation-averaged molecular orbital approximation. This more sophisticated model was found to be in closer agreement with the experimental data, however neither model accurately predicts the TDCS over all geometries and energies.

  3. Flexible 2D Crystals of Polycyclic Aromatics Stabilized by Static Distortion Waves.

    PubMed

    Meissner, Matthias; Sojka, Falko; Matthes, Lars; Bechstedt, Friedhelm; Feng, Xinliang; Müllen, Klaus; Mannsfeld, Stefan C B; Forker, Roman; Fritz, Torsten

    2016-07-26

    The epitaxy of many organic films on inorganic substrates can be classified within the framework of rigid lattices which helps to understand the origin of energy gain driving the epitaxy of the films. Yet, there are adsorbate-substrate combinations with distinct mutual orientations for which this classification fails and epitaxy cannot be explained within a rigid lattice concept. It has been proposed that tiny shifts in atomic positions away from ideal lattice points, so-called static distortion waves (SDWs), are responsible for the observed orientational epitaxy in such cases. Using low-energy electron diffraction and scanning tunneling microscopy, we provide direct experimental evidence for SDWs in organic adsorbate films, namely hexa-peri-hexabenzocoronene on graphite. They manifest as wave-like sub-Ångström molecular displacements away from an ideal adsorbate lattice which is incommensurate with graphite. By means of a density-functional-theory based model, we show that, due to the flexibility in the adsorbate layer, molecule-substrate energy is gained by straining the intermolecular bonds and that the resulting total energy is minimal for the observed domain orientation, constituting the orientational epitaxy. While structural relaxation at an interface is a common assumption, the combination of the precise determination of the incommensurate epitaxial relation, the direct observation of SDWs in real space, and their identification as the sole source of epitaxial energy gain constitutes a comprehensive proof of this effect.

  4. Flexible 2D Crystals of Polycyclic Aromatics Stabilized by Static Distortion Waves

    PubMed Central

    2016-01-01

    The epitaxy of many organic films on inorganic substrates can be classified within the framework of rigid lattices which helps to understand the origin of energy gain driving the epitaxy of the films. Yet, there are adsorbate–substrate combinations with distinct mutual orientations for which this classification fails and epitaxy cannot be explained within a rigid lattice concept. It has been proposed that tiny shifts in atomic positions away from ideal lattice points, so-called static distortion waves (SDWs), are responsible for the observed orientational epitaxy in such cases. Using low-energy electron diffraction and scanning tunneling microscopy, we provide direct experimental evidence for SDWs in organic adsorbate films, namely hexa-peri-hexabenzocoronene on graphite. They manifest as wave-like sub-Ångström molecular displacements away from an ideal adsorbate lattice which is incommensurate with graphite. By means of a density-functional-theory based model, we show that, due to the flexibility in the adsorbate layer, molecule–substrate energy is gained by straining the intermolecular bonds and that the resulting total energy is minimal for the observed domain orientation, constituting the orientational epitaxy. While structural relaxation at an interface is a common assumption, the combination of the precise determination of the incommensurate epitaxial relation, the direct observation of SDWs in real space, and their identification as the sole source of epitaxial energy gain constitutes a comprehensive proof of this effect. PMID:27014920

  5. Rapid relativistic distorted-wave approach for calculating cross sections for ionization of highly charged ions

    NASA Astrophysics Data System (ADS)

    Zhang, Hong Lin; Sampson, Douglas H.

    1990-11-01

    The rapid relativistic distorted-wave method of Zhang, Sampson, and Mohanty [Phys. Rev. A 40, 616 (1989)] for excitation, which uses the atomic-structure data of Sampson et al. [Phys. Rev. A 40, 604 (1989)], has been extended to ionization. In this approach the same Dirac-Fock-Slater potential evaluated using a single mean configuration is used in calculating the orbitals of all electrons bound and free. Values for the cross sections Q for ionization of various ions have been calculated, and generally good agreement is obtained with other recent relativistic calculations. When results are expressed in terms of the reduced ionization cross section QR, which is proportional to I2Q, they are close to the nonrelativistic Coulomb-Born-exchange values of Moores, Golden, and Sampson [J. Phys. B 13, 385 (1980)] for hydrogenic ions except for high Z and/or high energies. This suggests that fits of the QR to simple functions of the impact electron energy in threshold units with coefficients that are quite slowly varying functions of an effective Z can probably be made. This would be convenient for plasma-modeling applications.

  6. Distorted-wave born approximation calculations for turbulence scattering in an upward-refracting atmosphere

    NASA Technical Reports Server (NTRS)

    Gilbert, Kenneth E.; Di, Xiao; Wang, Lintao

    1990-01-01

    Weiner and Keast observed that in an upward-refracting atmosphere, the relative sound pressure level versus range follows a characteristic 'step' function. The observed step function has recently been predicted qualitatively and quantitatively by including the effects of small-scale turbulence in a parabolic equation (PE) calculation. (Gilbert et al., J. Acoust. Soc. Am. 87, 2428-2437 (1990)). The PE results to single-scattering calculations based on the distorted-wave Born approximation (DWBA) are compared. The purpose is to obtain a better understanding of the physical mechanisms that produce the step-function. The PE calculations and DWBA calculations are compared to each other and to the data of Weiner and Keast for upwind propagation (strong upward refraction) and crosswind propagation (weak upward refraction) at frequencies of 424 Hz and 848 Hz. The DWBA calculations, which include only single scattering from turbulence, agree with the PE calculations and with the data in all cases except for upwind propagation at 848 Hz. Consequently, it appears that in all cases except one, the observed step function can be understood in terms of single scattering from an upward-refracted 'skywave' into the refractive shadow zone. For upwind propagation at 848 Hz, the DWBA calculation gives levels in the shadow zone that are much below both the PE and the data.

  7. Expressions for Form Factors for Inelastic Scattering and Charge Exchange in Plane-Wave, Distorted-Wave, and Coupled-Channels Reaction Formalisms

    SciTech Connect

    Dietrich, F S

    2006-09-25

    This document is intended to facilitate calculation of inelastic scattering and charge-exchange cross sections in a variety of reaction models, including the plane-wave and distorted-wave approximations and the full coupled-channels treatments. Expressions are given for the coupling potentials between the relevant channels in both coordinate and momentum space. In particular, it is expected that the plane-wave calculations should be useful as a check on the correctness of coupled-channels calculations. The Fourier transform methods used to calculate the plane-wave approximation cross sections are also intended to be used to generate the transition potentials for coupled-channels codes, using a folding model with local effective interactions. Specific expressions are given for calculating transition densities for the folding model in the random phase approximation (RPA).

  8. Wave propagation and phase retrieval in Fresnel diffraction by a distorted-object approach

    SciTech Connect

    Xiao Xianghui; Shen Qun

    2005-07-15

    An extension of the far-field x-ray diffraction theory is presented by the introduction of a distorted object for calculation of coherent diffraction patterns in the near-field Fresnel regime. It embeds a Fresnel-zone construction on an original object to form a phase-chirped distorted object, which is then Fourier transformed to form a diffraction image. This approach extends the applicability of Fourier-based iterative phasing algorithms into the near-field holographic regime where phase retrieval had been difficult. Simulated numerical examples of this near-field phase retrieval approach indicate its potential applications in high-resolution structural investigations of noncrystalline materials.

  9. Direct measurement of wave-front distortion induced during second-harmonic generation: application to breakup-integral compensation.

    PubMed

    Caumes, Jean Pascal; Videau, Laurent; Rouyer, Claude; Freysz, Eric

    2004-04-15

    The wave-front distortion of femtosecond laser pulses recorded with a Shack-Hartmann analyzer makes it possible to retrieve the nonlinear index of refraction of different glasses and the nonlinear phase shift induced during second-harmonic generation in beta-barium borate (BBO) crystal versus the phase mismatch. It is shown that the nonlinear phase shift induced in a 2-mm-thick BBO crystal allows compensation for up to a 2pi breakup-integral induced in a 4-cm fused-silica glass. The stability of the compensation is reported to be from 10 to 100 GW cm(-2).

  10. Direct measurement of wave-front distortion induced during second-harmonic generation: application to breakup-integral compensation.

    PubMed

    Caumes, Jean Pascal; Videau, Laurent; Rouyer, Claude; Freysz, Eric

    2004-04-15

    The wave-front distortion of femtosecond laser pulses recorded with a Shack-Hartmann analyzer makes it possible to retrieve the nonlinear index of refraction of different glasses and the nonlinear phase shift induced during second-harmonic generation in beta-barium borate (BBO) crystal versus the phase mismatch. It is shown that the nonlinear phase shift induced in a 2-mm-thick BBO crystal allows compensation for up to a 2pi breakup-integral induced in a 4-cm fused-silica glass. The stability of the compensation is reported to be from 10 to 100 GW cm(-2). PMID:15119415

  11. An investigation of the open-loop amplification of Reynolds number dependent processes by wave distortion

    NASA Technical Reports Server (NTRS)

    Purdy, K. R.; Ventrice, M. B.; Fang, J.

    1972-01-01

    Analytical and experimental studies were initiated to determine if the response of a constant temperature hot wire anemometer to acoustic oscillations could serve as an analog to the response of the drop vaporization burning rate process to acoustic oscillations, and, perhaps, also as an analog to any Reynolds number dependent process. The motivation behind this study was a recent analytical study which showed that distorted acoustic oscillations could amplify the open-loop response of vaporization limited combustion. This type of amplification may be the cause of unstable combustion in liquid propellant rocket engines. The analytical results obtained for the constant temperature anemometer are similar in nature to those previously obtained for vaporization limited combustion and indicate that the response is dependent on the amount and type of distortion as well as other factors, such as sound pressure level, Mach number and hot wire temperature. Preliminary results indicate qualitative agreement between theory and experiment.

  12. Symmetry properties of the S matrix in a fully relativistic distorted-wave treatment of electron-impact ionization

    SciTech Connect

    Pyper, N. C.; Kampp, Marco; Whelan, Colm T.

    2005-05-15

    The symmetry properties of the S matrix in a fully relativistic distorted-wave treatment of electron-impact ionization are investigated. It is shown that the square modulus of the scattering matrix element in which the spin states of all four electrons are determined is not invariant under the reversal of the direction of alignment of all spins. The largest of two contributions to this noninvariance originates from the relativistic modifications of the continuum wave functions induced by the distorting potential of the target atom. A second smaller contribution is manifested on reducing the eight-dimensional matrix elements of the QED covariant propagator to purely spatial two-electron integrals. The triple differential cross section (TDCS) exhibits a spin asymmetry unless the entire scattering process occurs in a single plane. There will be a difference in the TDCS between an (e,2e) event in which the initial beam is polarized parallel or antiparallel with respect to the beam direction even if the target is unpolarized and the final spin states are not determined. The TDCS will remain unchanged if, in addition to reversal of the direction of spin alignment, one appropriate momentum component of one of the two outgoing electrons is reversed.

  13. Statistical multiple diffuse scattering from rough surfaces in RHEED — beyond the distorted-wave Born approximation

    NASA Astrophysics Data System (ADS)

    Wang, Z. L.

    1996-10-01

    In reflection high-energy electron diffraction (RHEED) of growing surfaces in molecular beam epitaxy (MBE), diffuse scattering is generated by atom vibrations, point vacancies and growth islands (or surface roughness). Most of the existing RHEED theories have been developed under the first-order diffuse scattering approximation, and thus they are restricted for surfaces whose roughness is relatively low. In fact, crystal surfaces grown by MBE are usually rough; the change of surface coverage from 0 to 1 monolayer accounts for the observed RHEED oscillation. In this paper, a formal dynamical theory of RHEED has been developed to calculate the diffuse scattering produced by both atom vibrations and point vacancies at surfaces. The theory is aimed at recovering the multiple diffuse scattering that has been dropped by the distorted-wave Born approximation (DWBA). With the inclusion of a complex potential in the dynamical calculation, a rigorous proof is given to show that the high-order diffuse scattering terms are recovered in the calculation using the equation originally derived under the DWBA. This conclusion establishes the basis for expanding the RHEED theories developed under the first-order diffuse scattering to cases where the degree of surface roughness is high, allowing dynamical calculation of RHEED rocking curves for any growing surface. The statistical time and structure averages over the distorted crystal potential are evaluated analytically before numerical calculation. The dynamic form factor is calculated with consideration of anisotropic surface atom vibration and point vacancies at a growing surface.

  14. Amplification of Reynolds number dependent processes by wave distortion. [acoustic instability of liquid propellant rocket engines

    NASA Technical Reports Server (NTRS)

    Ventrice, M. B.; Fang, J. C.; Purdy, K. R.

    1975-01-01

    A system using a hot-wire transducer as an analog of a liquid droplet of propellant was employed to investigate the ingredients of the acoustic instability of liquid-propellant rocket engines. It was assumed that the combustion process was vaporization-limited and that the combustion chamber was acoustically similar to a closed-closed right-circular cylinder. Before studying the hot-wire closed-loop system (the analog system), a microphone closed-loop system, which used the response of a microphone as the source of a linear feedback exciting signal, was investigated to establish the characteristics of self-sustenance of acoustic fields. Self-sustained acoustic fields were found to occur only at resonant frequencies of the chamber. In the hot-wire closed-loop system, the response of hot-wire anemometer was used as the source of the feedback exciting signal. The self-sustained acoustic fields which developed in the system were always found to be harmonically distorted and to have as their fundamental frquency a resonant frequency for which there also existed a second resonant frequency which was approximately twice the fundamental frequency.

  15. Dirac R-matrix and Breit-Pauli distorted wave calculations of the electron-impact excitation of W44+

    NASA Astrophysics Data System (ADS)

    Bluteau, M. M.; O'Mullane, M. G.; Badnell, N. R.

    2015-10-01

    With construction of ITER progressing and existing tokamaks carrying-out ITER-relevant experiments, accurate fundamental and derived atomic data for numerous ionization stages of tungsten (W) is required to assess the potential effect of this species upon fusion plasmas. The results of fully relativistic, partially radiation damped, Dirac R-matrix electron-impact excitation calculations for the {{{W}}}44+ ion are presented. These calculations use a configuration interaction and close-coupling expansion that opens-up the 3d-subshell; this does not appear to have been considered before in a collision calculation. As a result, it is possible to investigate the arrays, [3d104s2-3d94s24f] and [3d104s2-3d94s4p4d], which are predicted to contain transitions of diagnostic importance for the soft x-ray region. Our R-matrix collision data are compared with previous R-matrix results by Ballance and Griffin as well as our own relativistically corrected, Breit-Pauli distorted wave and plane-wave Born calculations. All relevant data are applied to the collisional-radiative modelling of atomic populations, for further comparison. This reveals the paramount nature of the 3d-subshell transitions from the perspectives of radiated power loss and detailed spectroscopy.

  16. Generation of acoustic rogue waves in dusty plasmas through three-dimensional particle focusing by distorted waveforms

    NASA Astrophysics Data System (ADS)

    Tsai, Ya-Yi; Tsai, Jun-Yi; I, Lin

    2016-06-01

    Rogue waves--rare uncertainly emerging localized events with large amplitudes--have been experimentally observed in many nonlinear wave phenomena, such as water waves, optical waves, second sound in superfluid He II (ref. ) and ion acoustic waves in plasmas. Past studies have mainly focused on one-dimensional (1D) wave behaviour through modulation instabilities, and to a lesser extent on higher-dimensional behaviour. The question whether rogue waves also exist in nonlinear 3D acoustic-type plasma waves, the kinetic origin of their formation and their correlation with surrounding 3D waveforms are unexplored fundamental issues. Here we report the direct experimental observation of dust acoustic rogue waves in dusty plasmas and construct a picture of 3D particle focusing by the surrounding tilted and ruptured wave crests, associated with the higher probability of low-amplitude holes for rogue-wave generation.

  17. Relativistic description of inclusive quasielastic proton-nucleus scattering with relativistic distorted-wave impulse approximation and random-phase approximation

    NASA Astrophysics Data System (ADS)

    van Niekerk, D. D.; van der Ventel, B. I. S.; Titus, N. P.; Hillhouse, G. C.

    2011-04-01

    We present a fully relativistic model for polarized inclusive quasielastic proton-nucleus scattering that includes relativistic distorted waves for the projectile and ejectile (RDWIA), as well as the relativistic random-phase approximation (RPA) applied to the target nucleus. Using a standard relativistic impulse approximation treatment of quasielastic scattering and a two-body Scalar, Pseudoscalar, Vector, Axial vector, Tensor (SPVAT) form of the current operator, it is shown how the behavior of the projectile/ejectile and target can be decoupled. Distortion effects are included via a full partial-wave expansion of the relativistic wave functions. Target correlations are included via the relativistic RPA applied to mean-field theory in quantum hadrodynamics. A number of novel analytical and numerical techniques are employed to aid in this highly nontrivial calculation. A baseline plane-wave calculation is performed for the reaction Ca40(p⃗,p⃗') at an energy of 500 MeV and an angle θc.m.=40°. Here it is found that the effect of isoscalar correlations is a quenching of the cross section that is expected to become more pronounced at lower energies or for higher-density targets. A RDWIA calculation shows additional reduction and if isoscalar target correlations are included this effect is enhanced.

  18. Relativistic description of inclusive quasielastic proton-nucleus scattering with relativistic distorted-wave impulse approximation and random-phase approximation

    SciTech Connect

    Niekerk, D. D. van; Ventel, B. I. S. van der; Titus, N. P.; Hillhouse, G. C.

    2011-04-15

    We present a fully relativistic model for polarized inclusive quasielastic proton-nucleus scattering that includes relativistic distorted waves for the projectile and ejectile (RDWIA), as well as the relativistic random-phase approximation (RPA) applied to the target nucleus. Using a standard relativistic impulse approximation treatment of quasielastic scattering and a two-body Scalar, Pseudoscalar, Vector, Axial vector, Tensor (SPVAT) form of the current operator, it is shown how the behavior of the projectile/ejectile and target can be decoupled. Distortion effects are included via a full partial-wave expansion of the relativistic wave functions. Target correlations are included via the relativistic RPA applied to mean-field theory in quantum hadrodynamics. A number of novel analytical and numerical techniques are employed to aid in this highly nontrivial calculation. A baseline plane-wave calculation is performed for the reaction {sup 40}Ca(p-vector,p-vector{sup '}) at an energy of 500 MeV and an angle {theta}{sub c.m.}=40 deg. Here it is found that the effect of isoscalar correlations is a quenching of the cross section that is expected to become more pronounced at lower energies or for higher-density targets. A RDWIA calculation shows additional reduction and if isoscalar target correlations are included this effect is enhanced.

  19. Integration of a laser doppler vibrometer and adaptive optics system for acoustic-optical detection in the presence of random water wave distortions

    NASA Astrophysics Data System (ADS)

    Land, Phillip; Robinson, Dennis; Roeder, James; Cook, Dean; Majumdar, Arun K.

    2016-05-01

    A new technique has been developed for improving the Signal-to-Noise Ratio (SNR) of underwater acoustic signals measured above the water's surface. This technique uses a Laser Doppler Vibrometer (LDV) and an Adaptive Optics (AO) system (consisting of a fast steering mirror, deformable mirror, and Shack-Hartmann Wavefront Sensor) for mitigating the effect of surface water distortions encountered while remotely recording underwater acoustic signals. The LDV is used to perform non-contact vibration measurements of a surface via a two beam laser interferometer. We have demonstrated the feasibility of this technique to overcome water distortions artificially generated on the surface of the water in a laboratory tank. In this setup, the LDV beam penetrates the surface of the water and travels down to be reflected off a submerged acoustic transducer. The reflected or returned beam is then recorded by the LDV as a vibration wave measurement. The LDV extracts the acoustic wave information while the AO mitigates the water surface distortions, increasing the overall SNR. The AO system records the Strehl ratio, which is a measure of the quality of optical image formation. In a perfect optical system the Strehl ratio is unity, however realistic systems with imperfections have Strehl ratios below one. The operation of the AO control system in open-loop and closed-loop configurations demonstrates the utility of the AO-based LDV for many applications.

  20. Does Bose-Einstein condensation of CMB photons cancel μ distortions created by dissipation of sound waves in the early Universe?

    NASA Astrophysics Data System (ADS)

    Khatri, R.; Sunyaev, R. A.; Chluba, J.

    2012-04-01

    The difference in the adiabatic indices of photons and non-relativistic baryonic matter in the early Universe causes the electron temperature to be slightly lower than the radiation temperature. Comptonization of photons with colder electrons results in the transfer of energy from photons to electrons and ions, owing to the recoil effect (spontaneous and induced). Thermalization of photons with a colder plasma results in the accumulation of photons in the Rayleigh-Jeans tail, aided by stimulated recoil, while the higher frequency spectrum tries to approach Planck spectrum at the electron temperature Tγfinal = Te < Tγinitial; i.e., Bose-Einstein condensation of photons occurs. We find new solutions of the Kompaneets equation describing this effect. No actual condensate is, in reality, possible since the process is very slow and photons drifting to low frequencies are efficiently absorbed by bremsstrahlung and double Compton processes. The spectral distortions created by Bose-Einstein condensation of photons are within an order of magnitude (for the present range of allowed cosmological parameters), with exactly the same spectrum but opposite in sign, of those created by diffusion damping of the acoustic waves on small scales corresponding to comoving wavenumbers 45 < k < 104 Mpc-1. The initial perturbations on these scales are completely unobservable today due to their being erased completely by Silk damping. There is partial cancellation of these two distortions, leading to suppression of μ distortions expected in the standard model of cosmology. The net distortion depends on the scalar power index ns and its running dns/dlnk, and may vanish for special values of parameters, for example, for a running spectrum with, ns = 1,dns/dlnk = - 0.038. We arrive at an intriguing conclusion: even a null result, non-detection of μ-type distortion at a sensitivity of 10-9, gives a quantitative measure of the primordial small-scale power spectrum.

  1. An investigation of the open-loop amplification of a Reynolds number dependent process by wave distortion

    NASA Technical Reports Server (NTRS)

    Ventrice, M. B.; Purdy, K. R.

    1974-01-01

    The response of a constant-temperature hot-wire anemometer to sinusoidal and distorted sinusoidal acoustic oscillations is examined. The output of the anemometer is dependent upon the Reynolds number of the flow over the wire. The response is a measure of the interaction between the anemometer output and the acoustic pressure in the neighborhood of the wire. It is an open-loop prediction of the characteristics of actual closed-loop operation of a system. If the open-loop response is large enough, unstable closed-loop operation is predicted. The study was motivated by a need to investigate the stability limits of liquid-propellant rockets when perturbed by pressure oscillations. The sinusoidal and distorted sinusoidal acoustic oscillations used for this study are the same as those characteristic of unstable rocket combustion. Qualitatively, the results are similar--the response of the system to pure sinusoidal acoustic vibration of the fluid surrounding the wire is small, even when the magnitude of the acoustic pressure is quite large; but the response can be increased by as much as an order of magnitude with respect to the sinusoidal case by the addition of distortion. The amplitude and phase of the distortion component, relative to the fundamental component, are the dominant factors in the increase in the response.

  2. Application of a post-collisional-interaction distorted-wave model for (e, 2e) of some atomic targets and methane

    NASA Astrophysics Data System (ADS)

    Chinoune, M.; Houamer, S.; Dal Cappello, C.; Galstyan, A.

    2016-10-01

    Recently Isik et al (2016 J. Phys B: At. Mol. Opt. Phys. 49 065203) performed measurements of the triple differential cross sections (TDCSs) of methane by electron impact. Their data clearly show that post-collisional interaction (PCI) effects are present in the angular distributions of ejected electrons. A model describing the ejected electron by a distorted wave and including PCI is applied for the single ionization of atomic targets and for methane. Extensive comparisons between this model and other previous models are made with available experiments.

  3. A special method for finding body distortions that reduce the wave drag of wing and body combinations at supersonic speeds

    NASA Technical Reports Server (NTRS)

    Lomax, Harvard; Heaslet, Max A

    1956-01-01

    For a given wing and supersonic Mach number, the problem of shaping an adjoining fuselage so that the combination will have a low wave drag is considered. Only fuselages that can be simulated by singularities (multipoles) distributed along the body axis are studied. However, the optimum variations of such singularities are completely specified in terms of the given wing geometry. An application is made to an elliptic wing having a biconvex section, a thickness-chord ratio equal to 0.05 at the root, and an aspect ratio equal to 3. A comparison of the theoretical results with a wind-tunnel experiment is also presented.

  4. Relativistic distorted-wave impulse approximation analysis of 12C(e,e'p) for Q2<2 (GeV/c)2

    NASA Astrophysics Data System (ADS)

    Kelly, James J.

    2005-06-01

    We analyze data for 12C(e,e'p) with Q2<2(GeV/c)2 using the relativistic distorted-wave impulse approximation (RDWIA) based upon Dirac-Hartree wave functions. The 1p normalization extracted from data for Q2>0.6 (GeV/c)2 is approximately 0.87, independent of Q2, which is consistent with the predicted depletion of the 1p3/2 orbital by short-range correlations. The total 1p and 1s strength for Em<80MeV approaches 100% of IPSM (independent particle shell model), consistent with a continuum contribution for 30wave functions fit to low Q2 data for parallel kinematics are too narrow to reproduce data for quasiperpendicular kinematics, especially for larger Q2, and are partly responsible for reducing fitted normalization factors. Although the RDWIA normalization factors for Q2<0.2(GeV/c)2 are also smaller than obtained for Q2>0.6(GeV/c)2, the effect is smaller, and we argue that it should be attributed to the effective single-nucleon current operator instead of to spectroscopic factors, which are probe-independent properties of nuclear structure. However, remediation of the failure of RDWIA calculations to reproduce low Q2 data for parallel kinematics will require a more sophisticated modification of the current method than a simple multiplicative factor.

  5. Transmission versus transflection mode in FTIR analysis of blood plasma: is the electric field standing wave effect the only reason for observed spectral distortions?

    PubMed

    Staniszewska-Slezak, Emilia; Rygula, Anna; Malek, Kamilla; Baranska, Malgorzata

    2015-04-01

    Fourier transform infrared (FTIR) microspectroscopy is assessed in terms of two techniques (i.e., transmission and transflection) as a method for rapid measurements of blood plasma. Apart from the expected effect of the electric field standing wave (EFSW), we also noticed that second-derivative IR spectra recorded in transflection mode exhibited a significant shift in the amide I band (up to 1667 cm(-1)) in comparison to the one recorded in transmission (1658 cm(-1)). This has not been reported thus far in studies of the EFSW distortion of IR spectra of biological material. The thinner the sample deposited on the low-e microscope slide, the lower the position of the amide I band found in FTIR spectra, suggesting various plasma compositions after stratification or certain changes in secondary protein conformations due to chemical and/or physical effects. There are potentially several phenomena that can occur at the surface of both IR substrates affecting the protein profile, including changes in optical properties (refractive index), variation in water content in the sample, and segregation of plasma components. All three hypotheses are discussed here, with the help of atomic force microscopy (AFM). PMID:25562064

  6. Amplifier Distortion

    NASA Astrophysics Data System (ADS)

    Keeports, David

    2006-12-01

    By definition, a high fidelity amplifier's instantaneous output voltage is directly proportional to its instantaneous input voltage. While high fidelity is generally valued in the amplification of recorded music, nonlinearity, also known as distortion, is desirable in the amplification of some musical instruments. In particular, guitar amplifiers exploit nonlinearity to increase both the harmonic content and sustain of a guitar's sound. I will discuss how both modifications in sound result from saturation of triode tubes and transistors. Additionally, I will describe the difference in the symmetry of saturation curves for transistors and tubes and the reason why tube guitar amplifiers are generally considered to be superior to solid-state amplifiers. Finally, I will discuss attempts to use solid-state electronics to replicate the sound of tube amplifiers.

  7. The antisymmetry of distortions

    PubMed Central

    VanLeeuwen, Brian K.; Gopalan, Venkatraman

    2015-01-01

    Distortions are ubiquitous in nature. Under perturbations such as stresses, fields or other changes, a physical system reconfigures by following a path from one state to another; this path, often a collection of atomic trajectories, describes a distortion. Here we introduce an antisymmetry operation called distortion reversal that reverses a distortion pathway. The symmetry of a distortion pathway is then uniquely defined by a distortion group; it has the same form as a magnetic group that involves time reversal. Given its isomorphism to magnetic groups, distortion groups could have a commensurate impact in the study of distortions, as the magnetic groups have had in the study of magnetic structures. Distortion symmetry has important implications for a range of phenomena such as structural and electronic phase transitions, diffusion, molecular conformational changes, vibrations, reaction pathways and interface dynamics. PMID:26572582

  8. Coupled commensurate charge density wave and lattice distortion in Na2Ti2P n2O (P n =As ,Sb ) determined by x-ray diffraction and angle-resolved photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Davies, N. R.; Johnson, R. D.; Princep, A. J.; Gannon, L. A.; Ma, J.-Z.; Qian, T.; Richard, P.; Li, H.; Shi, M.; Nowell, H.; Baker, P. J.; Shi, Y. G.; Ding, H.; Luo, J.; Guo, Y. F.; Boothroyd, A. T.

    2016-09-01

    We report single-crystal x-ray-diffraction measurements on Na2Ti2P n2O (P n =As ,Sb ) which reveal a charge superstructure that appears below the density wave transitions previously observed in bulk data. From symmetry-constrained structure refinements we establish that the associated distortion mode can be described by two propagation vectors q1=(1 /2 ,0 ,l ) and q2=(0 ,1 /2 ,l ) with l =0 (Sb) or l =1 /2 (As) and primarily involves in-plane displacements of the Ti atoms perpendicular to the Ti-O bonds. We also present angle-resolved photoemission spectroscopy measurements, which show band folding and backbending consistent with a density wave with the same wave-vectors q1 and q2 associated with Fermi-surface nesting, and muon-spin relaxation data, which show no indication of spin density wave order. The results provide direct evidence for phonon-assisted charge density wave order in Na2Ti2P n2O and fully characterize a proximate ordered phase that could compete with superconductivity in doped BaTi2Sb2O .

  9. Quantum phase diagram of distorted J 1 - J 2 Heisenberg S  =  1/2 antiferromagnet in honeycomb lattice: a modified spin wave study.

    PubMed

    Ghorbani, Elaheh; Shahbazi, Farhad; Mosadeq, Hamid

    2016-10-12

    Using the modified spin wave method, we study the [Formula: see text] Heisenberg model with first and second neighbor antiferromagnetic exchange interactions. For a symmetric S  =  1/2 model, with the same couplings for all the equivalent neighbors, we find three phases in terms of the frustration parameter [Formula: see text]: (1) a commensurate collinear ordering with staggered magnetization (Néel.I state) for [Formula: see text], (2) a magnetically gapped disordered state for [Formula: see text], preserving all the symmetries of the Hamiltonian and lattice, which by definition is a quantum spin liquid (QSL) state and (3) a commensurate collinear ordering in which two out of the three nearest neighbor magnetizations are antiparallel and the remaining pair are parallel (Néel.II state), for [Formula: see text]. We also explore the phase diagram of a distorted [Formula: see text] model with S  =  1/2. Distortion is introduced as an inequality of one nearest neighbor coupling with the other two. This yields a richer phase diagram by the appearance of a new gapped QSL, a gapless QSL and also a valence bond crystal phase in addition to the previous three phases found for the undistorted model. PMID:27518832

  10. Quantum phase diagram of distorted J 1 - J 2 Heisenberg S  =  1/2 antiferromagnet in honeycomb lattice: a modified spin wave study.

    PubMed

    Ghorbani, Elaheh; Shahbazi, Farhad; Mosadeq, Hamid

    2016-10-12

    Using the modified spin wave method, we study the [Formula: see text] Heisenberg model with first and second neighbor antiferromagnetic exchange interactions. For a symmetric S  =  1/2 model, with the same couplings for all the equivalent neighbors, we find three phases in terms of the frustration parameter [Formula: see text]: (1) a commensurate collinear ordering with staggered magnetization (Néel.I state) for [Formula: see text], (2) a magnetically gapped disordered state for [Formula: see text], preserving all the symmetries of the Hamiltonian and lattice, which by definition is a quantum spin liquid (QSL) state and (3) a commensurate collinear ordering in which two out of the three nearest neighbor magnetizations are antiparallel and the remaining pair are parallel (Néel.II state), for [Formula: see text]. We also explore the phase diagram of a distorted [Formula: see text] model with S  =  1/2. Distortion is introduced as an inequality of one nearest neighbor coupling with the other two. This yields a richer phase diagram by the appearance of a new gapped QSL, a gapless QSL and also a valence bond crystal phase in addition to the previous three phases found for the undistorted model.

  11. Quantum phase diagram of distorted J 1 - J 2 Heisenberg S  =  1/2 antiferromagnet in honeycomb lattice: a modified spin wave study

    NASA Astrophysics Data System (ADS)

    Ghorbani, Elaheh; Shahbazi, Farhad; Mosadeq, Hamid

    2016-10-01

    Using the modified spin wave method, we study the {{J}1}-{{J}2} Heisenberg model with first and second neighbor antiferromagnetic exchange interactions. For a symmetric S  =  1/2 model, with the same couplings for all the equivalent neighbors, we find three phases in terms of the frustration parameter \\barα={{J}2}/{{J}1} : (1) a commensurate collinear ordering with staggered magnetization (Néel.I state) for 0≤slant \\barα≲ 0.207 , (2) a magnetically gapped disordered state for 0.207≲ \\barα≲ 0.369 , preserving all the symmetries of the Hamiltonian and lattice, which by definition is a quantum spin liquid (QSL) state and (3) a commensurate collinear ordering in which two out of the three nearest neighbor magnetizations are antiparallel and the remaining pair are parallel (Néel.II state), for 0.396≲ \\barα≤slant 1 . We also explore the phase diagram of a distorted {{J}1}-{{J}2} model with S  =  1/2. Distortion is introduced as an inequality of one nearest neighbor coupling with the other two. This yields a richer phase diagram by the appearance of a new gapped QSL, a gapless QSL and also a valence bond crystal phase in addition to the previous three phases found for the undistorted model.

  12. Relativistic distorted wave collision strengths for excitation to the 88 n = 3 and n = 4 levels in all 71 neon-like ions with 22 less than or equal to Z less than or equal to 92

    SciTech Connect

    Zhang, Hong Lin; Sampson, D. H.

    1989-02-01

    Relativistic distorted wave collision strengths are given for the 88 possible transitions between the ground level and the excited levels with n = 3 and n = 4 in the 71 neon-like ions with nuclear charge number Z in the range 22 less than or equal to Z less than or equal to 92. The calculations are made for the six final, or scattered, electron energies E' = 0.008, 0.04, 0.10, 0.21, 0.41 and 0.75, where E' is in units of Z/sub eff//sup 2/ Rydbergs with Z/sub eff/ = Z /minus/ 7.5. In addition, the transition energies and electric dipole oscillator strengths are given. 10 refs., 4 tabs.

  13. Reducing the Distortion in Upward Distortion Data.

    ERIC Educational Resources Information Center

    Sussman, Lyle; Krivonos, Paul

    Because information flow is considered essential to an organization and because decision makers are dependent upon accurate information, the distortion of messages as they move upward in an organization has become a central concern of many organizational communication researchers. The purposes of this paper are to critically review the various…

  14. L{alpha}, L{beta}, and L{gamma} x-ray production cross sections of Hf, Ta, W, Re, Os, Au, Pb, and Bi by electron impact: Comparison of distorted-wave calculations with experiment

    SciTech Connect

    Fernandez-Varea, Jose M.; Segui, Silvina; Dingfelder, Michael

    2011-02-15

    We study the emission of L{alpha}, L{beta}, and L{gamma} characteristic x rays by the impact of electrons on Hf, Ta, W, Re, Os, Au, Pb, and Bi atoms. To this end, ionization cross sections of the L{sub 1}, L{sub 2}, and L{sub 3} subshells of these atoms are calculated within the distorted-wave Born approximation. The considered energy interval spans from the ionization threshold up to 50 keV. Atomic relaxation parameters (i.e., Coster-Kronig and radiative transition probabilities, fluorescence yields, and emission rates) taken from the literature are then used to evaluate x-ray production cross sections. The theoretical predictions are compared with published experimental information. Good agreement is found for Ta, W, Os, Au, Pb, and Bi. In the case of Hf and Re, the measured cross sections are lower than the theoretical estimates by around 30%. The observed discrepancies might be attributed to the methods employed to correct the raw experimental data for the excess of detected characteristic x rays caused by the finite thickness of the sample's active layer and the presence of the thick substrate.

  15. Relativistic distorted-wave collision strengths for Δn = 0 transitions in the 67 Li-like, F-like and Na-like ions with 26 ≤ Z ≤ 92

    DOE PAGES

    Fontes, Christopher J.; Zhang, Hong Lin

    2016-05-04

    We calculated relativistic distorted-wave collision strength for all possible Δn=0 transitions, where n denotes the valence shell of the ground level, in the 67 Li-like, F-like and Na-like ions with Z in the range 26 ≤ Z ≤92. This choice produces 3 transitions with n=2 in the Li-like and F-like ions, and 10 transitions with n=3 in the Na-like ions. Moreover, for the Li-like and F-like ions, the calculations were made for the six final, or scattered, electron energies E'=0.008,0.04,0.10,0.21,0.41, and 0.75, where E' is in units of Zmore » $$2\\atop{eff}$$ Ry with Zeff = Z- 1.66 for Li-like ions and Zeff= Z- 6.667 for F-like ions. For the Na-like ions, the calculations were made for the six final electron energies E'=0.0025,0.015,0.04,0.10,0.21, and 0.40, with Zeff = Z- 8.34. In the present calculations, an improved “top-up” method, which employs relativistic plane waves, was used to obtain the high partial-wave contribution for each transition, in contrast to the partial-relativistic Coulomb–Bethe approximation used in previous works by Zhang, Sampson and Fontes [H.L. Zhang, D.H. Sampson, C.J. Fontes, At. Data Nucl. Data Tables 44 (1990) 31; H.L. Zhang, D.H. Sampson, C.J. Fontes, At. Data Nucl. Data Tables 48 (1991) 25; D.H. Sampson, H.L. Zhang, C.J. Fontes, At. Data Nucl. Data Tables 44 (1990) 209]. In those previous works, collision strengths were also provided for Li-, F- and Na-like ions, but for a more comprehensive set of transitions. Finally, the collision strengths covered in the present work should be more accurate than the corresponding data given in those previous works and are presented here to replace those earlier results.« less

  16. Distortion free projection lithography

    SciTech Connect

    Hawryluk, A.M.; Ceglio, N.M.; Phillion, D.W.; Gaines, D.P.

    1991-07-09

    Soft x-ray projection lithography (SXPL) may be used to fabricate high resolution structures for future devices, but will require an all-reflecting optical system with {approximately} 100 nm resolution and < 10 nm image distortion over large fields-of-view. In present designs, the lithographic tool for SXPL is envisioned as a ring-field'' scanning system with multiple (3--5), possibly aspheric, imaging optics fabricated to {approximately} < 1 nm figure precision. In its present form, several technologies must be developed before this tool can become practical. A simple, non-scanning optical system with less expensive optics, reduced mirror reflection losses and lower source power requirements would be very attractive. We have developed a technique, called Encoded Mask Lithography (EML), which allows for distortion free, high resolution reticle replication over a large field-of-view while using an imaging system with substantial inherent distortion. When applied to SXPL, EML allows us to use a simple, two spherical mirror imaging system. The simplified optical system used in EML eases optic fabrication requirements, obviates the need for mask-to-wafer scanning, and decreases multilayer mirror reflection losses and source power requirements. Although developed for SXPL, this concept is applicable to all forms of projection lithography where distortion over large fields may be a problem. 10 refs., 4 figs.

  17. Charmless 3-BODY B Decays:. Resonant and Nonresonant Contributions

    NASA Astrophysics Data System (ADS)

    Cheng, Hai-Yang

    Charmless 3-body decays of B mesons are studied using a simple model based on the framework of the factorization approach. We have identified a large source of the nonresonant signal in the matrix elements of scalar densities, e.g. < K/line{K}∣ /line{s}s ∣ 0 >. This explains the dominance of the nonresonant background in B → KKK decays, the sizable nonresonant fraction of order (35 40)% in K-π+π- and /line{K}0π +π - modes and the smallness of nonresonant rates in B → πππ decays. We have computed the resonant and nonresonant contributions to charmless 3-body decays and determined the rates for the quasi-two-body decays B → VP and B → SP. Time-dependent CP asymmetries sin 2βeff and ACP in K+K-KS, KSKSKS, KSπ+π- and KSπ0π0 modes are estimated.

  18. Universal Relations for Identical Bosons from 3-Body Physics

    NASA Astrophysics Data System (ADS)

    Kang, Daekyoung; Platter, Lucas; Braaten, Eric

    2011-05-01

    Systems consisting of identical bosons with a large scattering length satisfy universal relations determined by 2-body physics that are similar to those for fermions with two spin states. They require the momentum distribution to have a large-momentum 1 /k4 tail and the radio-frequency transition rate to have a high-frequency 1 /ω 3 / 2 tail, both of which are proportional to the 2-body contact. Identical bosons also satisfy additional universal relations that are determined by 3-body physics and involve the 3-body contact, which measures the probability of 3 particles being very close together. The coefficients of the 3-body contact in the 1 /k5 tail of the momentum distribution and in the 1 /ω2 tail of the radio-frequency transition rate are log-periodic functions of k and ω that depend on the Efimov parameter. Supported in part by a joint grant from the ARO and the AFOSR and by a grant from the DOE.

  19. Triton's distorted atmosphere.

    PubMed

    Elliot, J L; Stansberry, J A; Olkin, C B; Agner, M A; Davies, M E

    1997-10-17

    A stellar-occultation light curve for Triton shows asymmetry that can be understood if Triton's middle atmosphere is distorted from spherical symmetry. Although a globally oblate model can explain the data, the inferred atmospheric flattening is so large that it could be caused only by an unrealistic internal mass distribution or highly supersonic zonal winds. Cyclostrophic winds confined to a jet near Triton's northern or southern limbs (or both) could also be responsible for the details of the light curve, but such winds are required to be slightly supersonic. Hazes and clouds in the atmosphere are unlikely to have caused the asymmetry in the light curve.

  20. Triton's Distorted Atmosphere

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.; Stansberry, J. A.; Olkin, C. B.; Agner, M. A.; Davies, M. E.

    1998-01-01

    A stellar-occultation light curve for Triton shows asymmetry that can be understood if Triton's middle atmosphere is distorted from spherical symmetry. Although a globally oblate model can explain the data, the inferred atmospheric flattening is so large that it could be caused only by an unrealistic internal mass distribution or highly supersonic zonal winds. Cyclostrophic winds confined to a jet near Triton's northern or southern limbs (or both) could also be responsible for the details of the light curve, but such winds are required to be slightly supersonic. Hazes and clouds in the atmosphere are unlikely to have caused the asymmetry in the light curve.

  1. Solution to the π-Distortivity Problem.

    PubMed

    Perumalla, D Sravanakumar; Sebastian, Kizhakeyil L

    2016-09-01

    Traditionally, the delocalized π system of benzene is believed to be responsible for its perfectly symmetric D6h geometry. However, it has also been suggested that the π system prefers a distorted D3h geometry. Arguments for this have been based on clever use of VB methods as well as through shifts in the frequency of the distortive b2u mode. Evidence has been provided through different ways of partitioning the total electronic energy between the σ and the π systems. These methods are plagued by the fact that there is no unique way to partition the energy, leading to questions regarding the validity of the conclusions. Here we note that even though energy cannot be partitioned exactly, force acting on a nucleus depends only on the single particle density and can hence be partitioned exactly. Using good-quality wave functions that are numerically found to obey the Hellmann-Feynman theorem to good accuracy, we calculate the σ and π components of the force and provide conclusive evidence of π-distortivity at the HF level. Our approach provides an unambiguous way to approach the problem with wave functions that account for electron correlation. Our calculations suggest that the conclusion is valid at the MP2 level, too. PMID:27504529

  2. Redshift-space distortions.

    PubMed

    Percival, Will J; Samushia, Lado; Ross, Ashley J; Shapiro, Charles; Raccanelli, Alvise

    2011-12-28

    Comparing measurements of redshift-space distortions (RSDs) with geometrical observations of the expansion of the Universe offers tremendous potential for testing general relativity on very large scales. The basic linear theory of RSDs in the distant-observer limit has been known for 25 years and the effect has been conclusively observed in numerous galaxy surveys. The next generation of galaxy survey will observe many millions of galaxies over volumes of many tens of Gpc(3). They will provide RSD measurements of such exquisite precision that we will have to carefully analyse and correct for many systematic deviations from this simple picture in order to fully exploit the statistical precision obtained. We review RSD theory and show how ubiquitous RSDs actually are, and then consider a number of potential systematic effects, shamelessly highlighting recent work in which we have been involved. This review ends by looking ahead to the future surveys that will make the next generation of RSD measurements.

  3. Cognitive Distortions and Suicide Attempts.

    PubMed

    Jager-Hyman, Shari; Cunningham, Amy; Wenzel, Amy; Mattei, Stephanie; Brown, Gregory K; Beck, Aaron T

    2014-08-01

    Although theorists have posited that suicidal individuals are more likely than non-suicidal individuals to experience cognitive distortions, little empirical work has examined whether those who recently attempted suicide are more likely to engage in cognitive distortions than those who have not recently attempted suicide. In the present study, 111 participants who attempted suicide in the 30 days prior to participation and 57 psychiatric control participants completed measures of cognitive distortions, depression, and hopelessness. Findings support the hypothesis that individuals who recently attempted suicide are more likely than psychiatric controls to experience cognitive distortions, even when controlling for depression and hopelessness. Fortune telling was the only cognitive distortion uniquely associated with suicide attempt status. However, fortune telling was no longer significantly associated with suicide attempt status when controlling for hopelessness. Findings underscore the importance of directly targeting cognitive distortions when treating individuals at risk for suicide.

  4. Inlet flow distortion in turbomachinery

    NASA Technical Reports Server (NTRS)

    Seidel, B. S.; Matwey, M. D.; Adamczyk, J. J.

    1980-01-01

    A single stage axial compressor with distorted inflow is studied. The inflow distortion occurs far upstream and may be a distortion in stagnation temperature, stagnation pressure or both. The blade rows are modeled as semi-actuator disks. Losses, quasi-steady deviation angles, and reference incidence correlations are included in the analysis. Both subsonic and transonic relative Mach numbers are considered. A parameter study is made to determine the influence of such variables as Mach number and swirl angle on the attenuation of the distortion.

  5. Memory distortion: an adaptive perspective

    PubMed Central

    Schacter, Daniel L.; Guerin, Scott A.; St. Jacques, Peggy L.

    2011-01-01

    Memory is prone to distortions that can have serious consequences in everyday life. Here we integrate emerging evidence that several types of memory distortions – imagination inflation, gist-based and associative memory errors, and post-event misinformation – reflect adaptive cognitive processes that contribute to the efficient functioning of memory, but produce distortions as a consequence of doing so. We consider recent cognitive and neuroimaging studies that link these distortions with adaptive processes, including simulation of future events, semantic and contextual encoding, creativity, and memory updating. We also discuss new evidence concerning factors that can influence the occurrence of memory distortions, such as sleep and retrieval conditions, as well as conceptual issues related to the development of an adaptive perspective. PMID:21908231

  6. Distorted stationary rotating black holes

    NASA Astrophysics Data System (ADS)

    Shoom, Andrey A.

    2015-03-01

    We study the interior of distorted stationary rotating black holes on the example of a Kerr black hole distorted by external static and axisymmetric mass distribution. We show that there is a duality transformation between the outer and inner horizons of the black hole, which is different from that of an electrically charged static distorted black hole. The duality transformation is directly related to the discrete symmetry of the space-time. The black hole horizon areas, surface gravity, and angular momentum satisfy the Smarr formula constructed for both the horizons. We formulate the zeroth, the first, and the second laws of black hole thermodynamics for both the horizons of the black hole and show the correspondence between the local and the global forms of the first law. The Smarr formula and the laws of thermodynamics formulated for both the horizons are related by the duality transformation. The distortion is illustrated on the example of a quadrupole and octupole fields. The distortion fields noticeably affect the proper time of a free fall from the outer to the inner horizon of the black hole along the symmetry semiaxes. There is some minimal nonzero value of the quadrupole and octupole moments when the time becomes minimal. The minimal proper time indicates the closest approach of the horizons due to the distortion.

  7. Stereo depth distortions in teleoperation

    NASA Technical Reports Server (NTRS)

    Diner, Daniel B.; Vonsydow, Marika

    1988-01-01

    In teleoperation, a typical application of stereo vision is to view a work space located short distances (1 to 3m) in front of the cameras. The work presented here treats converged camera placement and studies the effects of intercamera distance, camera-to-object viewing distance, and focal length of the camera lenses on both stereo depth resolution and stereo depth distortion. While viewing the fronto-parallel plane 1.4 m in front of the cameras, depth errors are measured on the order of 2cm. A geometric analysis was made of the distortion of the fronto-parallel plane of divergence for stereo TV viewing. The results of the analysis were then verified experimentally. The objective was to determine the optimal camera configuration which gave high stereo depth resolution while minimizing stereo depth distortion. It is found that for converged cameras at a fixed camera-to-object viewing distance, larger intercamera distances allow higher depth resolutions, but cause greater depth distortions. Thus with larger intercamera distances, operators will make greater depth errors (because of the greater distortions), but will be more certain that they are not errors (because of the higher resolution).

  8. Note on Redshift Distortion in Fourier Space

    NASA Astrophysics Data System (ADS)

    Cai, Yan-Chuan; Pan, Jun

    2007-02-01

    We explore features of redshift distortion in Fourier analysis of N-body simulations. The phases of the Fourier modes of dark matter density fluctuation are generally shifted by the peculiar motion along the line of sight, the induced phase shift is stochastic and has a probability distribution function (PDF) that is symmetric about the peak at zero shift and whose exact shape depends on the wave vector, except on very large scales where phases are invariant by linear perturbation theory. Analysis of the phase shifts motivates our phenomenological models for the bispectrum in redshift space. Comparison with simulations shows that our toy models are very successful in modeling bispectrum of equilateral and isosceles triangles at large scales. In the second part we compare the monopole of the power spectrum and bispectrum in the radial and plane-parallel distortion to test the plane-parallel approximation. We confirm the results of Scoccimarro that difference of power spectrum is at the level of 10%, and, in the reduced bispectrum, the difference is as small as a few percent. However, on the plane perpendicular to the line of sight of kz = 0, the difference in power spectrum between the radial and plane-parallel approximation can be more than ~10%, and even worse on very small scales. Such difference is prominent for bispectrum, especially for configurations of tilted triangles. Non-Gaussian signals under the radial distortion on small scales are systematically biased downside than are in the plane-parallel approximation, with amplitudes depending on the opening angle of the sample point to the observer. This observation gives warning to the practice of using the power spectrum and bispectrum measured on the kz = 0 plane as estimates of the real space statistics.

  9. JWST ISIM Distortion Analysis Challenge

    NASA Technical Reports Server (NTRS)

    Cifie, Emmanuel; Matzinger, Liz; Kuhn, Jonathan; Fan, Terry

    2004-01-01

    Very tight distortion requirements are imposed on the JWST's ISM structure due to the sensitivity of the telescope's mirror segment and science instrument positioning. The ISIM structure is a three dimensional truss with asymmetric gusseting and metal fittings. One of the primary challenges for ISIM's analysis team is predicting the thermal distortion of the structure both from the bulk cooldown from ambient to cryo, and the smaller temperature changes within the cryogenic operating environment. As a first cut to estimate thermal distortions, a finite element model of bar elements was created. Elements representing joint areas and metal fittings use effective properties that match the behavior of the stack-up of the composite tube, gusset and adhesive under mechanical and thermal loads. These properties were derived by matching tip deflections of a solid model simplified T-joint. Because of the structure s asymmetric gusseting, this effective property model is a first attempt at predicting rotations that cannot be captured with a smeared CTE approach. In addition to the finite element analysis, several first order calculations have been performed to gauge the feasibility of the material design. Because of the stringent thermal distortion requirements at cryogenic temperatures, a composite tube material with near zero or negative CTE is required. A preliminary hand analysis of the contribution of the various components along the distortion path between FGS and the other instruments, neglecting second order effects were examined. A plot of bounding tube longitudinal and transverse CTEs for thermal stability requirements was generated to help determine the feasibility of meeting these requirements. This analysis is a work in progress en route to a large degree of freedom hi-fidelity FEA model for distortion analysis. Methods of model reduction, such as superelements, are currently being investigated.

  10. Focal region fields of distorted reflectors

    NASA Technical Reports Server (NTRS)

    Buris, N. E.; Kauffman, J. F.

    1988-01-01

    The problem of the focal region fields scattered by an arbitrary surface reflector under uniform plane wave illumination is solved. The physical optics (PO) approximation is used to calculate the current induced on the reflector. The surface of the reflector is described by a number of triangular domain-wise 5th degree bivariate polynomials. A 2-dimensional Gaussian quadrature is employed to numerically evaluate the integral expressions of the scattered fields. No Freshnel or Fraunhofer zone approximations are made. The relation of the focal fields problem to surface compensation techniques and other applications are mentioned. Several examples of distorted parabolic reflectors are presented. The computer code developed is included, together with instructions on its usage.

  11. Optical compensation for hologram distortion using wavefront interpolation in angle-multiplexed holograms

    NASA Astrophysics Data System (ADS)

    Muroi, Tetsuhiko; Kinoshita, Nobuhiro; Ishii, Norihiko; Kamijo, Koji; Kawata, Yoshimasa; Kikuchi, Hiroshi

    2014-05-01

    Distortion of the hologram may occur when the photopolymer material used in the medium shrinks or expands. We analyzed interference fringe distortion for plane waves and a reference beam with an angular gap between recording and reproducing for the purpose of compensating for the distortion. We found that the wavefronts that could compensate for the distortion could approximately be obtained by linear interpolation of such angle-multiplexed holograms. We recorded 80 data pages with the angle-multiplexing method and obtained an optimized wavefront to compensate for hologram distortion on the first, fortieth, and eightieth data pages using adaptive optics with genetic algorithms and linear interpolated wavefronts at the other data pages. The calculation time for 80 wavefronts to compensate for distortion fell to 3/80th of that of having to calculate optimizations for all pages. The bit error rates were lower than 1.0 × 10-2 on all data pages reproduced using these wavefronts.

  12. USA/USSR Textbook Distortions.

    ERIC Educational Resources Information Center

    Parker, Franklin

    This review of a 1981 interim report on the United States' and the Soviet Union's distortion of events in history and geography textbooks is intended to encourage educators in both countries to depict the other side more honestly, less aggressively, and more appreciative of each other's virtues and flaws. Organized into two major sections,…

  13. Analysis of pressure distortion testing

    NASA Technical Reports Server (NTRS)

    Koch, K. E.; Rees, R. L.

    1976-01-01

    The development of a distortion methodology, method D, was documented, and its application to steady state and unsteady data was demonstrated. Three methodologies based upon DIDENT, a NASA-LeRC distortion methodology based upon the parallel compressor model, were investigated by applying them to a set of steady state data. The best formulation was then applied to an independent data set. The good correlation achieved with this data set showed that method E, one of the above methodologies, is a viable concept. Unsteady data were analyzed by using the method E methodology. This analysis pointed out that the method E sensitivities are functions of pressure defect level as well as corrected speed and pattern.

  14. Detection and Rectification of Distorted Fingerprints.

    PubMed

    Si, Xuanbin; Feng, Jianjiang; Zhou, Jie; Luo, Yuxuan

    2015-03-01

    Elastic distortion of fingerprints is one of the major causes for false non-match. While this problem affects all fingerprint recognition applications, it is especially dangerous in negative recognition applications, such as watchlist and deduplication applications. In such applications, malicious users may purposely distort their fingerprints to evade identification. In this paper, we proposed novel algorithms to detect and rectify skin distortion based on a single fingerprint image. Distortion detection is viewed as a two-class classification problem, for which the registered ridge orientation map and period map of a fingerprint are used as the feature vector and a SVM classifier is trained to perform the classification task. Distortion rectification (or equivalently distortion field estimation) is viewed as a regression problem, where the input is a distorted fingerprint and the output is the distortion field. To solve this problem, a database (called reference database) of various distorted reference fingerprints and corresponding distortion fields is built in the offline stage, and then in the online stage, the nearest neighbor of the input fingerprint is found in the reference database and the corresponding distortion field is used to transform the input fingerprint into a normal one. Promising results have been obtained on three databases containing many distorted fingerprints, namely FVC2004 DB1, Tsinghua Distorted Fingerprint database, and the NIST SD27 latent fingerprint database.

  15. Detection and Rectification of Distorted Fingerprints.

    PubMed

    Si, Xuanbin; Feng, Jianjiang; Zhou, Jie; Luo, Yuxuan

    2015-03-01

    Elastic distortion of fingerprints is one of the major causes for false non-match. While this problem affects all fingerprint recognition applications, it is especially dangerous in negative recognition applications, such as watchlist and deduplication applications. In such applications, malicious users may purposely distort their fingerprints to evade identification. In this paper, we proposed novel algorithms to detect and rectify skin distortion based on a single fingerprint image. Distortion detection is viewed as a two-class classification problem, for which the registered ridge orientation map and period map of a fingerprint are used as the feature vector and a SVM classifier is trained to perform the classification task. Distortion rectification (or equivalently distortion field estimation) is viewed as a regression problem, where the input is a distorted fingerprint and the output is the distortion field. To solve this problem, a database (called reference database) of various distorted reference fingerprints and corresponding distortion fields is built in the offline stage, and then in the online stage, the nearest neighbor of the input fingerprint is found in the reference database and the corresponding distortion field is used to transform the input fingerprint into a normal one. Promising results have been obtained on three databases containing many distorted fingerprints, namely FVC2004 DB1, Tsinghua Distorted Fingerprint database, and the NIST SD27 latent fingerprint database. PMID:26353261

  16. Distortions of Space and Time.

    PubMed

    Dodek

    1996-10-01

    A 15-year-old male was referred for evaluation of dizziness for the past 2 months. He complained of visual distortion and feeling of disorientation, was a poor student, and denied recreational drug use. His symptoms were consistent with the so-called "Alice in Wonderland" syndrome associated with Epstein-Barr virus infection. This case is an illustration of neurologic symptoms appearing without the features of infectious mononucleosis. PMID:10359980

  17. Transmission ratio distortion in mice.

    PubMed

    Lyon, Mary F

    2003-01-01

    The most studied example of transmission ratio distortion (TRD) in mice is that of the t-complex. This is a variant region of Chromosome 17 which exists as a polymorphism in wild mice. Males heterozygous for a t-haplotype and a normal Chr 17 transmit the t-haplotype to >50% of their young, up to 99%. Homozygous males are sterile. The TRD produced by the t-complex is due to the action of three or more distorter genes (Tcd) on a responder gene (Tcr). t-Haplotypes are maintained intact by crossover suppression induced by four neighboring inversions, the Tcd and Tcr loci lying in different inversions. Sperm formation is normal in t/t males, but sperm function is impaired through gross defects in sperm motility. The responder gene has been identified as a fusion gene formed from a sperm motility kinase and a ribosomal S6 kinase. Three candidate distorter genes have also been identified as genes coding for dynein chains, and thus possibly involved in sperm flagellar function. PMID:14616067

  18. Minimum distortion quantizers. [determined by max algorithm

    NASA Technical Reports Server (NTRS)

    Jones, H. W., Jr.

    1977-01-01

    The well-known algorithm of Max is used to determine the minimum distortion quantizers for normal, two-sided exponential, and specialized two-sided gamma input distributions and for mean-square, magnitude, and relative magnitude error distortion criteria. The optimum equally-spaced and unequally-spaced quantizers are found, with the resulting quantizer distortion and entropy. The quantizers, and the quantizers with entropy coding, are compared to the rate distortion bounds for mean-square and magnitude error.

  19. Testing inflation and curvaton scenarios with CMB distortions

    SciTech Connect

    Clesse, Sébastien; Garbrecht, Björn; Zhu, Yi E-mail: garbrecht@tum.de

    2014-10-01

    Prior to recombination, Silk damping causes the dissipation of energy from acoustic waves into the monopole of the Cosmic Microwave Background (CMB), resulting in spectral distortions. These can be used to probe the primordial scalar power spectrum on smaller scales than it is possible with CMB anisotropies. An enhancement of power on these scales is nevertheless required for the resulting distortions to be detectable by future experiments like PIXIE. In this paper, we examine all 49 single-field inflation models listed by Martin et al. in the Encyclopaedia Inflationaris [1] and find that only one of these may lead to a detectable level of distortions in a tuned region of its parameter space, namely the original hybrid model. Three effective multi-field scenarios are also studied: with softly and suddenly turning trajectories, and with a mild waterfall trajectory. Softly turning trajectories do not induce distortions at any detectable level, whereas a sudden turn in the field space or a mild waterfall trajectory predicts a peak (plus damped oscillations in the sudden turn case) in the scalar power spectrum, which can lead to an observable amount of CMB distortions. Finally, another scenario leading to potentially detectable distortions involves a curvaton whose blue spectrum is subdominant on CMB angular scales and overtakes the inflaton spectrum on smaller scales. In this case however, we show that the bounds from ultra compact minihaloes are not satisfied. Expectations for an ultimate PRISM-class experiment characterized by an improvement in sensitivity by a factor of ten are discussed for some models.

  20. On relative distortion in fingerprint comparison.

    PubMed

    Kalka, Nathan D; Hicklin, R Austin

    2014-11-01

    When fingerprints are deposited, non-uniform pressure in conjunction with the inherent elasticity of friction ridge skin often causes linear and non-linear distortions in the ridge and valley structure. The effects of these distortions must be considered during analysis of fingerprint images. Even when individual prints are not notably distorted, relative distortion between two prints can have a serious impact on comparison. In this paper we discuss several metrics for quantifying and visualizing linear and non-linear fingerprint deformations, and software tools to assist examiners in accounting for distortion in fingerprint comparisons.

  1. Analysis of Brown camera distortion model

    NASA Astrophysics Data System (ADS)

    Nowakowski, Artur; Skarbek, Władysław

    2013-10-01

    Contemporary image acquisition devices introduce optical distortion into image. It results in pixel displacement and therefore needs to be compensated for many computer vision applications. The distortion is usually modeled by the Brown distortion model, which parameters can be included in camera calibration task. In this paper we describe original model, its dependencies and analyze orthogonality with regard to radius for its decentering distortion component. We also report experiments with camera calibration algorithm included in OpenCV library, especially a stability of distortion parameters estimation is evaluated.

  2. Lens distortion calibration by explicit straight-line to distorted-line geometric mapping

    NASA Astrophysics Data System (ADS)

    Wu, Xianghai; Kofman, Jonathan

    2004-10-01

    Medium and wide-angle off-shelf cameras are often used in computer-vision applications despite their large lens distortion. Algorithms to correct for radial and tangential distortion are available; however, they often use non-linear optimization search methods that rely on carefully chosen starting points. This paper presents a method to correct for both radial symmetric lens distortion and decentering lens distortion using an iterative geometric approach to find the distortion center, and a closed-form solution for all other distortion parameters. The method is based on deriving an equivalent radial symmetric distortion model that accounts for both radial and tangential distortion. The technique uses the simple geometric relationship between a straight line and its distorted counterpart under this distortion model. The distortion calibration involves firstly determining the axis of symmetry of several distorted lines. The intersection of these axes is then computed and considered as the point of best radial symmetry (PBRS). The inclinations of the axes of symmetry of the distorted lines are then used in a closed-form solution to determine the distortion coefficients. One advantage of this approach is that higher-order coefficients can be included as needed, with their computation still achieved in closed form. The simplicity of the lens distortion calibration technique has been demonstrated in a simulation using synthetic images.

  3. The distorted tropane of scopoline.

    PubMed

    Écija, Patricia; Cocinero, Emilio J; Lesarri, Alberto; Basterretxea, Francisco J; Fernández, José A; Castaño, Fernando

    2013-06-24

    The structural isomerization of scopine into scopoline (oscine) has been observed in a supersonic jet expansion using microwave spectroscopy. The rotational spectrum evidences a single structure in the gas phase, providing a first description of the (three-ring) structurally distorted tropane in scopoline. The absence of rotational signatures of any scopine conformation suggests a practically quantitative isomerization at the vaporization temperatures of the experiment (ca. 90 °C). The determined rotational parameters of scopoline reveal the structural consequences of the intramolecular cyclation of scopine, which breaks the original epoxy group and creates a new ether bridge and a 7β-hydroxytropane configuration. The hydroxy group further stabilizes the molecule by an O-H⋅⋅⋅N intramolecular hydrogen bond, which, in turn, forces the N-methyl group to the less stable axial form. Supporting ab initio (MP2) and DFT (B3LYP, M06-2X) calculations are included.

  4. Dynamic Dazzle Distorts Speed Perception

    PubMed Central

    Hall, Joanna R.; Cuthill, Innes C.; Baddeley, Roland; Attwood, Angela S.; Munafò, Marcus R.; Scott-Samuel, Nicholas E.

    2016-01-01

    Static high contrast (‘dazzle’) patterns, such as zigzags, have been shown to reduce the perceived speed of an object. It has not escaped our notice that this effect has possible military applications and here we report a series of experiments on humans, designed to establish whether dynamic dazzle patterns can cause distortions of perceived speed sufficient to provide effective defence in the field, and the extent to which these effects are robust to a battery of manipulations. Dynamic stripe patterns moving in the same direction as the target are found to increase the perceived speed of that target, whilst dynamic stripes moving in the opposite direction to the target reduce the perceived speed. We establish the optimum position for such dazzle patches; confirm that reduced contrast and the addition of colour do not affect the performance of the dynamic dazzle, and finally, using the CO2 challenge, show that the effect is robust to stressful conditions. PMID:27196098

  5. Dynamic Dazzle Distorts Speed Perception.

    PubMed

    Hall, Joanna R; Cuthill, Innes C; Baddeley, Roland; Attwood, Angela S; Munafò, Marcus R; Scott-Samuel, Nicholas E

    2016-01-01

    Static high contrast ('dazzle') patterns, such as zigzags, have been shown to reduce the perceived speed of an object. It has not escaped our notice that this effect has possible military applications and here we report a series of experiments on humans, designed to establish whether dynamic dazzle patterns can cause distortions of perceived speed sufficient to provide effective defence in the field, and the extent to which these effects are robust to a battery of manipulations. Dynamic stripe patterns moving in the same direction as the target are found to increase the perceived speed of that target, whilst dynamic stripes moving in the opposite direction to the target reduce the perceived speed. We establish the optimum position for such dazzle patches; confirm that reduced contrast and the addition of colour do not affect the performance of the dynamic dazzle, and finally, using the CO2 challenge, show that the effect is robust to stressful conditions. PMID:27196098

  6. Evaluation of aero-optical distortion effects in PIV

    NASA Astrophysics Data System (ADS)

    Elsinga, G. E.; Oudheusden, B. W.; Scarano, F.

    2005-08-01

    Aero-optical distortion effects on the accuracy of particle image velocimetry (PIV) are investigated. When the illuminated particles are observed through a medium that is optically inhomogeneous due to flow compressibility, the resulting particle image pattern is subjected to deformation and blur. In relation to PIV two forms of error can be identified: position error and velocity error. In this paper a model is presented that describes these errors and particle image blur in relation to the refractive index field of the flow. In the case of 2D flows the model equations can be simplified and, furthermore, the background oriented schlieren technique (BOS) can be applied as a means to assess and correct for the optical error in PIV. The model describing the optical distortion is validated by both computer simulation and real experiments of 2D flows. Two flow features are considered: one with optical distortion normal to the velocity (shear layer) and one with optical distortion in the direction of the flow (expansion fan). Both simulation and experiments demonstrate that the major source for the velocity error is the second derivative of the refractive index in the direction of the velocity vector. The aero-optical distortion effect is less critical for shearing interfaces in comparison with compression/expansion fronts, the most critical case being represented by shock waves. Based on the results from the simulated experiments, it is concluded that for the 2D flow case the BOS method allows a measurement of the mean velocity error in PIV and can reduce it to a large extent.

  7. Image distortion analysis using polynomial series expansion.

    PubMed

    Baggenstoss, Paul M

    2004-11-01

    In this paper, we derive a technique for analysis of local distortions which affect data in real-world applications. In the paper, we focus on image data, specifically handwritten characters. Given a reference image and a distorted copy of it, the method is able to efficiently determine the rotations, translations, scaling, and any other distortions that have been applied. Because the method is robust, it is also able to estimate distortions for two unrelated images, thus determining the distortions that would be required to cause the two images to resemble each other. The approach is based on a polynomial series expansion using matrix powers of linear transformation matrices. The technique has applications in pattern recognition in the presence of distortions. PMID:15521492

  8. Frequency modulation television analysis: Distortion analysis

    NASA Technical Reports Server (NTRS)

    Hodge, W. H.; Wong, W. H.

    1973-01-01

    Computer simulation is used to calculate the time-domain waveform of standard T-pulse-and-bar test signal distorted in passing through an FM television system. The simulator includes flat or preemphasized systems and requires specification of the RF predetection filter characteristics. The predetection filters are modeled with frequency-symmetric Chebyshev (0.1-db ripple) and Butterworth filters. The computer was used to calculate distorted output signals for sixty-four different specified systems, and the output waveforms are plotted for all sixty-four. Comparison of the plotted graphs indicates that a Chebyshev predetection filter of four poles causes slightly more signal distortion than a corresponding Butterworth filter and the signal distortion increases as the number of poles increases. An increase in the peak deviation also increases signal distortion. Distortion also increases with the addition of preemphasis.

  9. Static stereo vision depth distortions in teleoperation

    NASA Technical Reports Server (NTRS)

    Diner, D. B.; Von Sydow, M.

    1988-01-01

    A major problem in high-precision teleoperation is the high-resolution presentation of depth information. Stereo television has so far proved to be only a partial solution, due to an inherent trade-off among depth resolution, depth distortion and the alignment of the stereo image pair. Converged cameras can guarantee image alignment but suffer significant depth distortion when configured for high depth resolution. Moving the stereo camera rig to scan the work space further distorts depth. The 'dynamic' (camera-motion induced) depth distortion problem was solved by Diner and Von Sydow (1987), who have quantified the 'static' (camera-configuration induced) depth distortion. In this paper, a stereo image presentation technique which yields aligned images, high depth resolution and low depth distortion is demonstrated, thus solving the trade-off problem.

  10. Optimized laser turrets for minimum phase distortion

    NASA Technical Reports Server (NTRS)

    Vanderplaats, G. N.; Fuhs, A. E.; Blaisdell, G. A.

    1980-01-01

    An analysis and computer program which optimizes laser turret geometry to obtain minimum phase distortion is described. Phase distortion due to compressible, inviscid flow over small perturbation laser turrets in subsonic or supersonic flow is calculated. The turret shape is determined by a two dimensional Fourier series; in a similar manner, the flow properties are given by a Fourier series. Phase distortion is calcualted for propagation at serveral combinations of elevation and azimuth angles. A sum is formed from the set of values, and this sum becomes the objective function for an optimization computer program. The shape of the turret is varied to provide minimum phase distortion.

  11. Cognitive Distortions, Humor Styles, and Depression.

    PubMed

    Rnic, Katerina; Dozois, David J A; Martin, Rod A

    2016-08-01

    Cognitive distortions are negative biases in thinking that are theorized to represent vulnerability factors for depression and dysphoria. Despite the emphasis placed on cognitive distortions in the context of cognitive behavioural theory and practice, a paucity of research has examined the mechanisms through which they impact depressive symptomatology. Both adaptive and maladaptive styles of humor represent coping strategies that may mediate the relation between cognitive distortions and depressive symptoms. The current study examined the correlations between the frequency and impact of cognitive distortions across both social and achievement-related contexts and types of humor. Cognitive distortions were associated with reduced use of adaptive Affiliative and Self-Enhancing humor styles and increased use of maladaptive Aggressive and Self-Defeating humor. Reduced use of Self-Enhancing humor mediated the relationship between most types of cognitive distortions and depressed mood, indicating that distorted negative thinking may interfere with an individual's ability to adopt a humorous and cheerful outlook on life (i.e., use Self-Enhancing humor) as a way of regulating emotions and coping with stress, thereby resulting in elevated depressive symptoms. Similarly, Self-Defeating humor mediated the association of the social impact of cognitive distortions with depression, such that this humor style may be used as a coping strategy for dealing with distorted thinking that ultimately backfires and results in increased dysphoria. PMID:27547253

  12. Cognitive Distortions, Humor Styles, and Depression

    PubMed Central

    Rnic, Katerina; Dozois, David J. A.; Martin, Rod A.

    2016-01-01

    Cognitive distortions are negative biases in thinking that are theorized to represent vulnerability factors for depression and dysphoria. Despite the emphasis placed on cognitive distortions in the context of cognitive behavioural theory and practice, a paucity of research has examined the mechanisms through which they impact depressive symptomatology. Both adaptive and maladaptive styles of humor represent coping strategies that may mediate the relation between cognitive distortions and depressive symptoms. The current study examined the correlations between the frequency and impact of cognitive distortions across both social and achievement-related contexts and types of humor. Cognitive distortions were associated with reduced use of adaptive Affiliative and Self-Enhancing humor styles and increased use of maladaptive Aggressive and Self-Defeating humor. Reduced use of Self-Enhancing humor mediated the relationship between most types of cognitive distortions and depressed mood, indicating that distorted negative thinking may interfere with an individual’s ability to adopt a humorous and cheerful outlook on life (i.e., use Self-Enhancing humor) as a way of regulating emotions and coping with stress, thereby resulting in elevated depressive symptoms. Similarly, Self-Defeating humor mediated the association of the social impact of cognitive distortions with depression, such that this humor style may be used as a coping strategy for dealing with distorted thinking that ultimately backfires and results in increased dysphoria. PMID:27547253

  13. Cognitive Distortions, Humor Styles, and Depression.

    PubMed

    Rnic, Katerina; Dozois, David J A; Martin, Rod A

    2016-08-01

    Cognitive distortions are negative biases in thinking that are theorized to represent vulnerability factors for depression and dysphoria. Despite the emphasis placed on cognitive distortions in the context of cognitive behavioural theory and practice, a paucity of research has examined the mechanisms through which they impact depressive symptomatology. Both adaptive and maladaptive styles of humor represent coping strategies that may mediate the relation between cognitive distortions and depressive symptoms. The current study examined the correlations between the frequency and impact of cognitive distortions across both social and achievement-related contexts and types of humor. Cognitive distortions were associated with reduced use of adaptive Affiliative and Self-Enhancing humor styles and increased use of maladaptive Aggressive and Self-Defeating humor. Reduced use of Self-Enhancing humor mediated the relationship between most types of cognitive distortions and depressed mood, indicating that distorted negative thinking may interfere with an individual's ability to adopt a humorous and cheerful outlook on life (i.e., use Self-Enhancing humor) as a way of regulating emotions and coping with stress, thereby resulting in elevated depressive symptoms. Similarly, Self-Defeating humor mediated the association of the social impact of cognitive distortions with depression, such that this humor style may be used as a coping strategy for dealing with distorted thinking that ultimately backfires and results in increased dysphoria.

  14. Simultaneous Multiplane Imaging with a Distorted Diffraction Grating

    NASA Astrophysics Data System (ADS)

    Blanchard, Paul M.; Greenaway, Alan H.

    1999-11-01

    We describe a simple technique for simultaneously imaging multiple layers within an object field onto a single camera. The approach uses a binary diffraction grating in which the lines are distorted such that a different level of defocus is associated with each diffraction order. The design of the gratings is discussed, and their ability to image multiple object planes is validated experimentally. Extension of the technique for spherical-aberration correction is described, and it is shown how the gratings can be used as part of a wave-front sensing system.

  15. Traversable wormholes in distorted gravity

    NASA Astrophysics Data System (ADS)

    Garattini, Remo

    2015-07-01

    In this paper, we consider the effects of distorted gravity on the traversability of the wormholes. In particular, we consider configurations which are sustained by their own gravitational quantum fluctuations. The Ultraviolet divergences appearing to one loop are taken under control with the help of a Noncommutative geometry representation and gravity's rainbow. In this context, it will be shown that for every framework, the self-sustained equation will produce a Wheeler wormhole, namely a wormhole of Planckian size. This means that, from the point of view of traversability, the wormhole will be traversable in principle, but not in practice. For this purpose, in the context of gravity's rainbow we have considered different proposals of rainbow's functions to see if the smallness of the wormhole is dependent on the chosen form of the rainbow's function. Unfortunately, we discover that this is not the case and we suggest that the self-sustained equation can be improved to see if the wormhole radius can be enlarged or not. Some consequences on topology change are discussed.

  16. Distortion Of Pressure Signals In Pneumatic Tubes

    NASA Technical Reports Server (NTRS)

    Whitmore, Stephen A.; Gilyard, Glenn B.; Curry, Robert; Lindsey, William

    1993-01-01

    NASA technical memorandum describes experimental investigation of distorting effects of propagation of pressure signals along narrow pneumatic tubes from pressure-sensing orifices on surfaces of models or aircraft to pressure sensors distant from orifices. Pressure signals distorted principally by frictional damping along walls of tubes and by reflections at orifice and sensor ends.

  17. Self-Compassion and Interpersonal Cognitive Distortions

    ERIC Educational Resources Information Center

    Akin, Ahmet

    2010-01-01

    The purpose of this study is to examine the relationships between self-compassion and interpersonal cognitive distortions. Participants were 338 university students. In this study, the Self-compassion Scale and the Interpersonal Cognitive Distortions Scale were used. The relationships between self-compassion and interpersonal cognitive distortions…

  18. Combined pressure and temperature distortion effects on internal flow of a turbofan engine

    NASA Technical Reports Server (NTRS)

    Braithwaite, W. M.; Soeder, R. H.

    1979-01-01

    An additional data base for improving and verifying a computer simulation developed by an engine manufacturer was obtained. The multisegment parallel compressor simulation was designed to predict the effects of steady-state circumferential inlet total-pressure and total-temperature distortions on the flows into and through a turbofan compression system. It also predicts the degree of distortion that will result in surge of the compressor. The effect of combined 180 deg square-wave distortion patterns of total pressure and total temperature in various relative positions is reported. The observed effects of the combined distortion on a unitary bypass ratio turbofan engine are presented in terms of total and static pressure profiles and total temperature profiles at stations ahead of the inlet guide vanes as well as through the fan-compressor system. These observed profiles are compared with those predicted by the complex multisegment model. The effects of relative position of the two components comprising the combined distortion on the degree resulting in surge are discussed. Certain relative positions required less combined distortion than either a temperature or pressure distortion by itself.

  19. Compensation for 6.5 K cryogenic distortion of a fused quartz mirror by refiguring

    NASA Technical Reports Server (NTRS)

    Augason, Gordon C.; Young, Jeffrey A.; Melugin, Ramsey K.; Clarke, Dana S.; Howard, Steven D.; Scanlan, Michael; Wong, Steven; Lawton, Kenneth C.

    1993-01-01

    A 46 cm diameter, lightweight, Amersil TO8E, fused-natural-quartz mirror with a single-arch cross section was tested at the NASA-Ames Research Center Cryogenic Optical Test Facility to measure its cryogenic distortion at 6.5 K. Then the mirror was refigured with the inverse of the measured cryogenic distortion to compensate for this figure defect. The mirror was retested at 6.5 K and found to have a significantly improved figure. The compensation for cryogenic distortion was not complete, but preliminary analysis indicates that the compensation was better than 0.25 waves P-V if edge effects are ignored. The feasibility of compensating for cryogenic distortion by refiguring has thus been verified.

  20. The lattice distortion effect for zinc-blende CrAs and CrSb

    NASA Astrophysics Data System (ADS)

    Yamana, Keita; Geshi, Masaaki; Tsukamoto, Hidekazu; Uchida, Ichiro; Shirai, Masafumi; Kusakabe, Koichi; Suzuki, Naoshi

    2004-12-01

    We investigated the stability of the ferromagnetism of CrAs and CrSb in the zinc-blende structure against the lattice distortion, systematically. A calculation within the generalized gradient approximation using a full potential linearized augmented plane wave method was performed. We compared the ferromagnetic state and the antiferromagnetic state assuming tetragonal distortion with the lattice constants a and c changing independently and determined the spin polarization ratio in the ferromagnetic phase. The result shows that complete spin polarization (half-metallic ferromagnetism) remains stable even in the presence of large tetragonal distortion. On the other hand, our calculation shows that two monolayers of CrAs is enough to produce a half-metallic state in the CrAs/GaAs multilayer. Thus, the present result suggests that the half-metallic nature persists in various atomic-scale superlattices made of distorted CrAs or CrSb.

  1. Correction of walk-off induced wavefront distortion for continuous-variable applications

    NASA Astrophysics Data System (ADS)

    Zou, Hongxin; Shen, Yong; Guo, Hong

    2016-05-01

    We theoretically and experimentally investigate wave front distortion in critically phase matched continuous-wave (CW) second harmonic generation (SHG). Due to the walk-off effect in the nonlinear crystal, the generated second harmonic is extremely elliptical and quite non-Gaussian, which causes a very low matching and coupling efficiency in experiment. Cylindrical lenses and walk-off compensating crystals are adopted to correct distorted wave fronts, and obtain a good TEM00 mode efficiency. Theoretically we simulate the correction effect of 266nm laser generated with SHG. The experiment results accord well with theoretical simulation and above 80 percent TEM00 component is obtained for 266nm continuous wave laser with 4.8 degree walk-off angle in BBO crystal. After that, an optical mode cleaner is used to obtain an ideal Gaussian mode. With these treatments, the generated second harmonic can be utilized in continuous-variable regime, where almost perfect mode matching is demanded.

  2. Shock turbulence interaction in the presence of mean shear - An application of rapid distortion theory

    NASA Technical Reports Server (NTRS)

    Mahesh, Krishnan; Lele, Sanjiva K.; Moin, Parviz

    1993-01-01

    The present examination of the response of anisotropic turbulent flows to a shock wave uses incompressible, homogeneous rapid distortion theory and idealizes the shock-wave as 1D compression. Attention is given to the shock's effect on axisymmetric flow and both the normal and oblique cases for shear flow. The oblique angle between the directions of compression and shear significantly affects turbulence evolution. Compression amplifies all components of turbulence intensity.

  3. Gravitational Effects on Distortion in Sintering

    NASA Technical Reports Server (NTRS)

    German, Randall M.

    2003-01-01

    During sintering a powder compact gains strength through low-temperature interparticle bonding, usually induced by solid-state surface diffusion, followed by further strength contributions from high-temperature densification. In cases where a liquid phase forms, sintering densification is accelerated and shape retention is sustained while open pores remain and contribute capillary forces. Unfortunately, sintering densification requires the compact become thermally softened to a point where creep strain rates reach levels near 10(exp -2)/s when the liquid forms. On the other hand, thermal softening of the powder compact substantially reduces the strength at high temperatures. Therefore, the in situ strength evolution during sintering is a primary focus to separate compact densification (as required for high performance) with minimized distortion (as required for net-shaping). With respect to gravitation effects on distortion during sintering there are two points of substantial weakness - prior to significant interparticle bonding and during final pore closure. This research is focused on understanding the competition among interparticle neck growth, densification, thermal softening, grain boundary wetting, capillary effects associated with liquid wetting and residual porosity, and gravity. Most surprising is the apparent role of gravity, where the deviatoric stress acting on the powder structure induces skeletal formation that reduces distortion. In contrast with theory, microgravity samples exhibit more distortion yet fail to fully densify. Results are presented on the experimental concepts supporting an emerging model of sintering strength evolution that enables understanding of both distortion and densification. The experiments have relied on tungsten heavy alloys, various combinations of dihedral angle, pore size, initial porosity, liquid:solid ratio, and heating rates. On Earth, the dominant factor with respect to distortion is the starting body heterogeneity

  4. Spectral distortions of the cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Adams, Fred C.; Mcdowell, Jonathan C.; Freese, Katherine; Levin, Janna

    1989-01-01

    Recent experiments indicate that the spectrum of the cosmic microwave background deviates from a pure blackbody; here, spectral distortions produced by cosmic dust are considered. The main result is that cosmic dust in conjunction with an injected radiation field (perhaps produced by an early generation of very massive stars) can explain the observed spectral distortions without violating existing cosmological constraints. In addition, it is shown that Compton y-distortions can also explain the observed spectral shape, but the energetic requirements are more severe.

  5. Distortion in the frequency demodulator using feedback.

    NASA Technical Reports Server (NTRS)

    Hoffman, E.; Schilling, D. L.

    1972-01-01

    The response of a frequency demodulator using feedback (FMFB) to a frequency modulated signal is analyzed. Canonical equations of operation are obtained. Harmonic distortion is calculated for the case of a sinusoidal modulating signal. Intermodulation distortion is calculated assuming a noise-like modulation. Design curves are presented. The special case of harmonic and intermodulation distortion in a discriminator is also presented. It is shown that the results obtained in this paper by treating the discriminator as a degenerate FMFB compare favorably with those obtained by other authors. However, the results presented here do not require digital computation.

  6. Reinforcing capabilities of television distortion1

    PubMed Central

    Greene, Robert J.; Hoats, David L.

    1969-01-01

    The effectiveness of television distortion as a negative reinforcer was analyzed. Contingency arrangements involving television distortion were found to be capable of (a) accelerating the work rate of a naive, mildly retarded subject on a simulated production-line task involving card-sorting, and (b) reducing gross hyperactivity of a mildly retarded subject. An escape-avoidance contingency was arranged for the production-line behavior of the first subject and a punishment contingency for the hyperactive behavior of the second subject. Television distortion appears to be an effective and practical negative reinforcer for use in behavior modification. PMID:16795211

  7. Microwave background distortions from domain walls

    NASA Technical Reports Server (NTRS)

    Goetz, Guenter; Noetzold, Dirk

    1990-01-01

    Domain walls arising in a cosmic phase transition after decoupling were recently proposed as seeds for the formation of large scale structure. The distortion induced in the microwave background radiation is calculated in dependence of the wall thickness, surface density, scalar field potential, cosmic redshift and the velocity of the wall. It was found that the maximal redshift distortion for both spherical and planar walls is of the order pi G sigma H(sup -1)(sub 0), where sigma is the surface energy density and H(sup -1)(sub 0) the Hubble parameter. It was also found that, for a wall thickness smaller than the horizon, walls can be treated as infinitely thin, i.e., the redshift distortion is independent of the wall thickness and the specific form of the scalar potential. For planar walls moving with a Lorentz-factor gamma the redshift distortion is enhanced by gamma cubed.

  8. Low distortion automatic phase control circuit

    NASA Technical Reports Server (NTRS)

    Hauge, G.; Pederson, C. W.

    1972-01-01

    Circuit for generation and demodulation of quadrature double side band signals in frequency division multiplexing system is described. Circuit is designed to produce low distortion automatic phase control. Illustration of circuit and components is included.

  9. Evaluating computed distortions of parabolic reflectors

    NASA Technical Reports Server (NTRS)

    Katow, M. S.

    1977-01-01

    Distortion outputs from structural analysis of a 64-m paraboloidal reflector are analyzed by two computer programs for their radio-frequency performance characteristics. The computed and field measured values are compared.

  10. Microwave diode amplifiers with low intermodulation distortion

    NASA Technical Reports Server (NTRS)

    Cooper, H. W.; Cohn, M.; Buck, D. C.

    1975-01-01

    Distortions can be greatly reduced in narrow-band applications by using the second harmonic. The ac behavior of simplified diode amplifier has negative resistance depending on slope of equivalent I-V curve.

  11. Healthy Weight: The Truth About Portion Distortion

    MedlinePlus

    ... calories are in today's large pizza slices? A chicken Caesar salad was 1 ½ cups and had ... How many calories are in today's 3 cup chicken Caesar salad? Portion Distortion Answers 350 calories 590 ...

  12. Vacuum polarization near a distorted black hole

    NASA Astrophysics Data System (ADS)

    Frolov, V. P.; Alberto García, D.

    1983-12-01

    The vacuum polarization near a black hole distorted by the axially symmetric gravitational field of external matter is studied. The explicit expression for <φ2> at the pole of the distorted horizon is obtained. Also at Sección de Graduados, Escuela Superior de Ingeniería Mecánica y Eléctrica del IPN, México DF, México.

  13. Coulomb Distortion in the Inelastic Regime

    SciTech Connect

    Patricia Solvignon, Dave Gaskell, John Arrington

    2009-09-01

    The Coulomb distortion effects have been for a long time neglected in deep inelastic scattering for the good reason that the incident energies were very high. But for energies in the range of earlier data from SLAC or at JLab, the Coulomb distortion could have the potential consequence of affecting the A-dependence of the EMC effect and of the longitudinal to transverse virtual photon absorption cross section ratio $R(x,Q^2)$.

  14. Electromagnetic wave test

    NASA Astrophysics Data System (ADS)

    Matthews, R. K.; Stepanek, S. A.

    Electromagnetic wave testing, which represents a relatively new test technique that involves the union of several disciplines (aerothermodynamics, electromagnetics, materials/structures, and advanced diagnostics) is introduced. The essence of this new technique deals with the transmission and possible distortion of electromagnetic waves (RF or IR) as they pass through the bow shock, flow field, and electromagnetic window of a missile flying at hypersonic speeds. Variations in gas density along the optical path can cause significant distortion of the electromagnetic waves and, therefore the missile seeker system may not effectively track the target. Two specific test techniques are described. The first example deals with the combining of a wind tunnel and an RF range while the second example discusses the complexities of evaluating IR seeker system performance.

  15. Investigating 3-body Decays of Cluster States with the PAT-TPC

    NASA Astrophysics Data System (ADS)

    Carpenter, Lisa; Ayyad Limonge, Y.; Bazin, D.; Beceiro-Novo, S.; Bradt, J.; Cortesi, M.; Mittig, W.; Ahn, T.; Kolata, J. J.; Meisel, Z.; Bechetti, F. D.; Fritsch, A.; Howard, A.

    2016-03-01

    Recent model calculations with most advanced methods for cluster states have shown the need of experimental data to probe the structure of light exotic nuclei, including those with α-clustering, such as 14C. The Prototype Active Target Time Projection Chamber (PAT-TPC) allows us to investigate these types of structures, giving access to the full excitation function with a single beam energy. This type of experiment measures resonances in 14C that can be compared to the models. With an improved Micromegas pad plane with a circular backgammon design we are able to investigate 3-body decays in addition to 2-body scattering. The measurements were carried out by resonant alpha-scattering on 10Be beam delivered by the TwinSol facility at the University of Notre Dame. We also observed the 3-body decay of the Hoyle State in 12C from a 12N or 12B beam with the same device. Preliminary results will be presented. This work is supported by the National Science Foundation.

  16. The Thermal Distortion of a Funnel Mold

    NASA Astrophysics Data System (ADS)

    Hibbeler, Lance C.; Thomas, Brian G.; Schimmel, Ronald C.; Abbel, Gert

    2012-10-01

    This article investigates the thermal distortion of a funnel mold for continuous casting of thin slabs and explores the implications on taper and solidification of the steel shell. The three-dimensional mold temperatures are calculated using shell-mold heat flux and cooling water profiles that were calibrated with plant measurements. The thermal stresses and distorted shape of the mold are calculated with a detailed finite-element model of a symmetric fourth of the entire mold and waterbox assembly, and they are validated with plant thermocouple data and measurements of the wear of the narrow-face copper mold plates. The narrow-face mold distorts into the typical parabolic arc, and the wide face distorts into a "W" shape owing to the large variation in bolt stiffnesses. The thermal expansion of the wide face works against the applied narrow-face taper and funnel effects, so the effect of thermal distortion must be considered to accurately predict the ideal mold taper.

  17. Plasticity and Awareness of Bodily Distortion.

    PubMed

    Pazzaglia, Mariella; Zantedeschi, Marta

    2016-01-01

    Knowledge of the body is filtered by perceptual information, recalibrated through predominantly innate stored information, and neurally mediated by direct sensory motor information. Despite multiple sources, the immediate prediction, construction, and evaluation of one's body are distorted. The origins of such distortions are unclear. In this review, we consider three possible sources of awareness that inform body distortion. First, the precision in the body metric may be based on the sight and positioning sense of a particular body segment. This view provides information on the dual nature of body representation, the reliability of a conscious body image, and implicit alterations in the metrics and positional correspondence of body parts. Second, body awareness may reflect an innate organizational experience of unity and continuity in the brain, with no strong isomorphism to body morphology. Third, body awareness may be based on efferent/afferent neural signals, suggesting that major body distortions may result from changes in neural sensorimotor experiences. All these views can be supported empirically, suggesting that body awareness is synthesized from multimodal integration and the temporal constancy of multiple body representations. For each of these views, we briefly discuss abnormalities and therapeutic strategies for correcting the bodily distortions in various clinical disorders. PMID:27630779

  18. Zero-distortion lossless data embedding

    NASA Astrophysics Data System (ADS)

    Nagaraj, Nithin; Mullick, Rakesh

    2004-05-01

    All known methods of lossless or reversible data embedding that exist today suffer from two major disadvantages: 1) The embedded image suffers from distortion, however small it may be by the very process of embedding and 2) The requirement of a special parser (decoder), which is necessary for the client to remove the embedded data in order to obtain the original image (lossless). We propose a novel lossless data embedding method where both these disadvantages are circumvented. Zero-distortion lossless data embedding (ZeroD-LDE) claims 'zero-distortion' of the embedded image for all viewing purposes and further maintaining that clients without any specialized parser can still recover the original image losslessly but would not have direct access to the embedded data. The fact that not all gray levels are used by most images is exploited to embed data by selective lossless compression of run-lengths of zeros (or any compressible pattern). Contiguous runs of zeros are changed such that the leading zero is made equal to the maximum original intensity plus the run-length and the succeeding zeros are converted to the embedded data (plus maximum original intensity) thus achieving extremely high embedding capacities. This way, the histograms of the host-data and the embedded data do not overlap and hence we can obtain zero-distortion by using the window-level setting of standard DICOM viewers. The embedded image is thus not only DICOM compatible but also zero-distortion visually and requires no clinical validation.

  19. Plasticity and Awareness of Bodily Distortion

    PubMed Central

    Zantedeschi, Marta

    2016-01-01

    Knowledge of the body is filtered by perceptual information, recalibrated through predominantly innate stored information, and neurally mediated by direct sensory motor information. Despite multiple sources, the immediate prediction, construction, and evaluation of one's body are distorted. The origins of such distortions are unclear. In this review, we consider three possible sources of awareness that inform body distortion. First, the precision in the body metric may be based on the sight and positioning sense of a particular body segment. This view provides information on the dual nature of body representation, the reliability of a conscious body image, and implicit alterations in the metrics and positional correspondence of body parts. Second, body awareness may reflect an innate organizational experience of unity and continuity in the brain, with no strong isomorphism to body morphology. Third, body awareness may be based on efferent/afferent neural signals, suggesting that major body distortions may result from changes in neural sensorimotor experiences. All these views can be supported empirically, suggesting that body awareness is synthesized from multimodal integration and the temporal constancy of multiple body representations. For each of these views, we briefly discuss abnormalities and therapeutic strategies for correcting the bodily distortions in various clinical disorders.

  20. Calibration of cameras with radially symmetric distortion.

    PubMed

    Tardif, Jean-Philippe; Sturm, Peter; Trudeau, Martin; Roy, Sébastien

    2009-09-01

    We present algorithms for plane-based calibration of general radially distorted cameras. By this, we understand cameras that have a distortion center and an optical axis such that the projection rays of pixels lying on a circle centered on the distortion center form a right viewing cone centered on the optical axis. The camera is said to have a single viewpoint (SVP) if all such viewing cones have the same apex (the optical center); otherwise, we speak of NSVP cases. This model encompasses the classical radial distortion model [5], fisheyes, and most central or noncentral catadioptric cameras. Calibration consists in the estimation of the distortion center, the opening angles of all viewing cones, and their optical centers. We present two approaches of computing a full calibration from dense correspondences of a single or multiple planes with known euclidean structure. The first one is based on a geometric constraint linking viewing cones and their intersections with the calibration plane (conic sections). The second approach is a homography-based method. Experiments using simulated and a broad variety of real cameras show great stability. Furthermore, we provide a comparison with Hartley-Kang's algorithm [12], which, however, cannot handle such a broad variety of camera configurations, showing similar performance.

  1. Plasticity and Awareness of Bodily Distortion

    PubMed Central

    Zantedeschi, Marta

    2016-01-01

    Knowledge of the body is filtered by perceptual information, recalibrated through predominantly innate stored information, and neurally mediated by direct sensory motor information. Despite multiple sources, the immediate prediction, construction, and evaluation of one's body are distorted. The origins of such distortions are unclear. In this review, we consider three possible sources of awareness that inform body distortion. First, the precision in the body metric may be based on the sight and positioning sense of a particular body segment. This view provides information on the dual nature of body representation, the reliability of a conscious body image, and implicit alterations in the metrics and positional correspondence of body parts. Second, body awareness may reflect an innate organizational experience of unity and continuity in the brain, with no strong isomorphism to body morphology. Third, body awareness may be based on efferent/afferent neural signals, suggesting that major body distortions may result from changes in neural sensorimotor experiences. All these views can be supported empirically, suggesting that body awareness is synthesized from multimodal integration and the temporal constancy of multiple body representations. For each of these views, we briefly discuss abnormalities and therapeutic strategies for correcting the bodily distortions in various clinical disorders. PMID:27630779

  2. Expertise and processing distorted structure in chess

    PubMed Central

    Bartlett, James C.; Boggan, Amy L.; Krawczyk, Daniel C.

    2013-01-01

    A classic finding in research on human expertise and knowledge is that of enhanced memory for stimuli in a domain of expertise as compared to either stimuli outside that domain, or within-domain stimuli that have been degraded or distorted in some way. However, we do not understand how experts process degradation or distortion of stimuli within the expert domain (e.g., a face with the eyes, nose, and mouth in the wrong positions, or a chessboard with pieces placed randomly). Focusing on the domain of chess, we present new fMRI evidence that when experts view such distorted/within-domain stimuli, they engage an active search for structure—a kind of exploratory chunking—that involves a component of a prefrontal-parietal network linked to consciousness, attention and working memory. PMID:24348371

  3. Core-nucleus distortation in hypernuclei

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.

    1995-08-01

    We are completing a study of the effects of the spherical distortion of the {open_quotes}core{close_quotes} nucleus by the {Lambda} in a hypernucleus. The response of the core was determined by an appropriately chosen energy-density functional which depends, in particular, on the nuclear compressibility. The forcing action of the A is determined by the nuclear density dependence of the {Lambda} binding in nuclear matter which is obtained from our work on the {Lambda} single-particle energies. Because of the strongly repulsive {Lambda}NN forces, this {Lambda} binding {open_quotes}saturates{close_quotes} at a density close to the central density of nuclei, and results in a reduced core-nucleus distortion much less than would otherwise be obtained. The effects of the core distortion then turn out to be very small even for quite light hypernuclei. This result justifies the assumption that spherical core nuclei are effectively undistorted in a hypernucleus.

  4. Minimal distortion pathways in polyhedral rearrangements.

    PubMed

    Casanova, David; Cirera, Jordi; Llunell, Miquel; Alemany, Pere; Avnir, David; Alvarez, Santiago

    2004-02-18

    A definition of minimum distortion paths between two polyhedra in terms of continuous shape measures (CShM) is presented. A general analytical expression deduced for such pathways makes use of one parameter, the minimum distortion constant, that can be easily obtained through the CShM methodology and is herein tabulated for pairs of polyhedra having four to eight vertexes. The work presented here also allows us to obtain representative model molecular structures along the interconversion pathways. Several commonly used polytopal rearrangement pathways are shown to be in fact minimum distortion pathways: the spread path leading from the tetrahedron to the square, the Berry pseudorotation that interconverts a square pyramid and a trigonal bipyramid, and the Bailar twist for the interconversion of the octahedron and the trigonal prism. Examples of applications to the analysis of the stereochemistries of several families of metal complexes are presented. PMID:14871107

  5. Dynamic Inlet Distortion Prediction with a Combined Computational Fluid Dynamics and Distortion Synthesis Approach

    NASA Technical Reports Server (NTRS)

    Norby, W. P.; Ladd, J. A.; Yuhas, A. J.

    1996-01-01

    A procedure has been developed for predicting peak dynamic inlet distortion. This procedure combines Computational Fluid Dynamics (CFD) and distortion synthesis analysis to obtain a prediction of peak dynamic distortion intensity and the associated instantaneous total pressure pattern. A prediction of the steady state total pressure pattern at the Aerodynamic Interface Plane is first obtained using an appropriate CFD flow solver. A corresponding inlet turbulence pattern is obtained from the CFD solution via a correlation linking root mean square (RMS) inlet turbulence to a formulation of several CFD parameters representative of flow turbulence intensity. This correlation was derived using flight data obtained from the NASA High Alpha Research Vehicle flight test program and several CFD solutions at conditions matching the flight test data. A distortion synthesis analysis is then performed on the predicted steady state total pressure and RMS turbulence patterns to yield a predicted value of dynamic distortion intensity and the associated instantaneous total pressure pattern.

  6. Objects exhibit body model like shape distortions.

    PubMed

    Saulton, Aurelie; Dodds, Trevor J; Bülthoff, Heinrich H; de la Rosa, Stephan

    2015-05-01

    Accurate knowledge about size and shape of the body derived from somatosensation is important to locate one's own body in space. The internal representation of these body metrics (body model) has been assessed by contrasting the distortions of participants' body estimates across two types of tasks (localization task vs. template matching task). Here, we examined to which extent this contrast is linked to the human body. We compared participants' shape estimates of their own hand and non-corporeal objects (rake, post-it pad, CD-box) between a localization task and a template matching task. While most items were perceived accurately in the visual template matching task, they appeared to be distorted in the localization task. All items' distortions were characterized by larger length underestimation compared to width. This pattern of distortion was maintained across orientation for the rake item only, suggesting that the biases measured on the rake were bound to an item-centric reference frame. This was previously assumed to be the case only for the hand. Although similar results can be found between non-corporeal items and the hand, the hand appears significantly more distorted than other items in the localization task. Therefore, we conclude that the magnitude of the distortions measured in the localization task is specific to the hand. Our results are in line with the idea that the localization task for the hand measures contributions of both an implicit body model that is not utilized in landmark localization with objects and other factors that are common to objects and the hand.

  7. Interaction of upstream flow distortions with high Mach number cascades

    NASA Technical Reports Server (NTRS)

    Englert, G. W.

    1981-01-01

    Features of the interaction of flow distortions, such as gusts and wakes with blade rows of advance type fans and compressors having high tip Mach numbers are modeled. A typical disturbance was assumed to have harmonic time dependence and was described, at a far upstream location, in three orthogonal spatial coordinates by a double Fourier series. It was convected at supersonic relative to a linear cascade described as an unrolled annulus. Conditions were selected so that the component of this velocity parallel to the axis of the turbomachine was subsonic, permitting interaction between blades through the upstream as well as downstream flow media. A strong, nearly normal shock was considered in the blade passages which was allowed curvature and displacement. The flows before and after the shock were linearized relative to uniform mean velocities in their respective regions. Solution of the descriptive equations was by adaption of the Wiener-Hopf technique, enabling a determination of distortion patterns through and downstream of the cascade as well as pressure distributions on the blade and surfaces. Details of interaction of the disturbance with the in-passage shock were discussed. Infuences of amplitude, wave length, and phase of the disturbance on lifts and moments of cascade configurations are presented. Numerical results are clarified by reference to an especially orderly pattern of upstream vertical motion in relation to the cascade parameters.

  8. A Study on 3-Body Abrasive Wear Behaviour of Aluminium 8011 / Graphite Metal Matrix Composite

    NASA Astrophysics Data System (ADS)

    Latha Shankar, B.; Anil, K. C.; Patil, Rahul

    2016-09-01

    Metals and alloys have found their vital role in many applications like structural, corrosive, tribological, etc., in engineering environment. The alloys/composites having high strength to low weight ratio have gained attention of many researchers recently. In this work, graphite reinforced Aluminium 8011 metal matrix composite was prepared by conventional stir casting route, by varying the weight % of reinforcement. Uniform distribution of Graphite in matrix alloy was confirmed by optical micrographs. Prepared composite specimens were subjected to 3-body abrasive testing by varying applied load and time, the silica particles of 400 grit size were used as abrasive particles. It was observed that with the increase of weight% of Graphite the wear resistance of composite was also increasing and on comparison it was found that reinforced composite gives good wear resistance than base alloy.

  9. Low distortion transform for reversible watermarking.

    PubMed

    Coltuc, Dinu

    2012-01-01

    This paper proposes a low-distortion transform for prediction-error expansion reversible watermarking. The transform is derived by taking a simple linear predictor and by embedding the expanded prediction error not only into the current pixel but also into its prediction context. The embedding ensures the minimization of the square error introduced by the watermarking. The proposed transform introduces less distortion than the classical prediction-error expansion for complex predictors such as the median edge detector or the gradient-adjusted predictor. Reversible watermarking algorithms based on the proposed transform are analyzed. Experimental results are provided.

  10. Reflective optical imaging system with balanced distortion

    DOEpatents

    Chapman, Henry N.; Hudyma, Russell M.; Shafer, David R.; Sweeney, Donald W.

    1999-01-01

    An optical system compatible with short wavelength (extreme ultraviolet) An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate. The four optical elements comprise, in order from object to image, convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention enables the use of larger slit dimensions associated with ring field scanning optics, improves wafer throughput and allows higher semiconductor device density. The inventive optical system is characterized by reduced dynamic distortion because the static distortion is balanced across the slit width.

  11. Zigzag laser with reduced optical distortion

    DOEpatents

    Albrecht, Georg F.; Comaskey, Brian; Sutton, Steven B.

    1994-01-01

    The architecture of the present invention has been driven by the need to solve the beam quality problems inherent in Brewster's angle tipped slab lasers. The entrance and exit faces of a solid state slab laser are cut perpendicular with respect to the pump face, thus intrinsically eliminating distortion caused by the unpumped Brewster's angled faces. For a given zigzag angle, the residual distortions inherent in the remaining unpumped or lightly pumped ends may be reduced further by tailoring the pump intensity at these ends.

  12. Zigzag laser with reduced optical distortion

    DOEpatents

    Albrecht, G.F.; Comaskey, B.; Sutton, S.B.

    1994-04-19

    The architecture of the present invention has been driven by the need to solve the beam quality problems inherent in Brewster's angle tipped slab lasers. The entrance and exit faces of a solid state slab laser are cut perpendicular with respect to the pump face, thus intrinsically eliminating distortion caused by the unpumped Brewster's angled faces. For a given zigzag angle, the residual distortions inherent in the remaining unpumped or lightly pumped ends may be reduced further by tailoring the pump intensity at these ends. 11 figures.

  13. Kekule-distortion-induced exciton instability in graphene

    SciTech Connect

    Dillenschneider, Raoul

    2008-09-15

    Effects of a Kekule distortion on exciton instability in single-layer graphene are discussed. In the framework of quantum electrodynamics the mass of the electron generated dynamically is worked out using a Schwinger-Dyson equation. For homogeneous lattice distortion it is shown that the generated mass is independent of the amplitude of the lattice distortion at the one-loop approximation. Formation of excitons induced by the homogeneous Kekule distortion could appear only through direct dependence of the lattice distortion.

  14. SQUARE WAVE AMPLIFIER

    DOEpatents

    Leavitt, M.A.; Lutz, I.C.

    1958-08-01

    An amplifier circuit is described for amplifying sigmals having an alternating current component superimposed upon a direct current component, without loss of any segnnent of the alternating current component. The general circuit arrangement includes a vibrator, two square wave amplifiers, and recombination means. The amplifier input is connected to the vibrating element of the vibrator and is thereby alternately applied to the input of each square wave amplifier. The detailed circuitry of the recombination means constitutes the novelty of the annplifier and consists of a separate, dual triode amplifier coupled to the output of each square wave amplifier with a recombination connection from the plate of one amplifier section to a grid of one section of the other amplifier. The recombination circuit has provisions for correcting distortion caused by overlapping of the two square wave voltages from the square wave amplifiers.

  15. Properties of the distorted Kerr black hole

    SciTech Connect

    Abdolrahimi, Shohreh; Tzounis, Christos; Kunz, Jutta; Nedkova, Petya E-mail: jutta.kunz@uni-oldenburg.de E-mail: tzounis@ualberta.ca

    2015-12-01

    We investigate the properties of the ergoregion and the location of the curvature singularities for the Kerr black hole distorted by the gravitational field of external sources. The particular cases of quadrupole and octupole distortion are studied in detail. We also investigate the scalar curvature invariants of the horizon and compare their behaviour with the case of the isolated Kerr black hole. In a certain region of the parameter space the ergoregion consists of a compact region encompassing the horizon and a disconnected part extending to infinity. The curvature singularities in the domain of outer communication, when they exist, are always located on the boundary of the ergoregion. We present arguments that they do not lie on the compact ergosurface. For quadrupole distortion the compact ergoregion size is negatively correlated with the horizon angular momentum when the external sources are varied. For octupole distortion infinitely many ergoregion configurations can exist for a certain horizon angular momentum. For some special cases we can have J{sup 2}/M{sup 4} > 1 and yet avoid a naked singularity.

  16. Rate-distortion theory and human perception.

    PubMed

    Sims, Chris R

    2016-07-01

    The fundamental goal of perception is to aid in the achievement of behavioral objectives. This requires extracting and communicating useful information from noisy and uncertain sensory signals. At the same time, given the complexity of sensory information and the limitations of biological information processing, it is necessary that some information must be lost or discarded in the act of perception. Under these circumstances, what constitutes an 'optimal' perceptual system? This paper describes the mathematical framework of rate-distortion theory as the optimal solution to the problem of minimizing the costs of perceptual error subject to strong constraints on the ability to communicate or transmit information. Rate-distortion theory offers a general and principled theoretical framework for developing computational-level models of human perception (Marr, 1982). Models developed in this framework are capable of producing quantitatively precise explanations for human perceptual performance, while yielding new insights regarding the nature and goals of perception. This paper demonstrates the application of rate-distortion theory to two benchmark domains where capacity limits are especially salient in human perception: discrete categorization of stimuli (also known as absolute identification) and visual working memory. A software package written for the R statistical programming language is described that aids in the development of models based on rate-distortion theory. PMID:27107330

  17. A rate distortion approach to protein symmetry.

    PubMed

    Wallace, Rodrick

    2010-08-01

    A spontaneous symmetry breaking argument is applied to the problem of protein folding, via a rate distortion analysis of the relation between genome coding and the final condensation of the protein molten globule that is, in spirit, analogous to Tlusty's (2007) exploration of the evolution of the genetic code. In the 'energy' picture, the average distortion between codon message and final protein structure, under constraints driven by evolutionary selection, serves as a temperature analog, so that low values limit the possible distribution of protein forms, producing the canonical folding funnel. A dual 'developmental' perspective sees the rate distortion function itself as the temperature analog, and permits incorporation of chaperons or toxic exposures as catalysts, driving the system to different possible outcomes or affecting the rate of convergence. The rate distortion function appears constrained by the availability of metabolic free energy, with implications for prebiotic evolution, and a nonequilibrium empirical Onsager treatment provides an adaptable statistical model that can be fitted to data, in the same manner as a regression equation. In sum, mechanistic models of protein folding fail to account for the observed spectrum of protein folding and aggregation disorders, suggesting that a biologically based cognitive paradigm describing folding will be needed for understanding the etiology, prevention, and treatment of these diseases. The developmental formalism introduced here may contribute substantially to such a paradigm.

  18. Rate-distortion theory and human perception.

    PubMed

    Sims, Chris R

    2016-07-01

    The fundamental goal of perception is to aid in the achievement of behavioral objectives. This requires extracting and communicating useful information from noisy and uncertain sensory signals. At the same time, given the complexity of sensory information and the limitations of biological information processing, it is necessary that some information must be lost or discarded in the act of perception. Under these circumstances, what constitutes an 'optimal' perceptual system? This paper describes the mathematical framework of rate-distortion theory as the optimal solution to the problem of minimizing the costs of perceptual error subject to strong constraints on the ability to communicate or transmit information. Rate-distortion theory offers a general and principled theoretical framework for developing computational-level models of human perception (Marr, 1982). Models developed in this framework are capable of producing quantitatively precise explanations for human perceptual performance, while yielding new insights regarding the nature and goals of perception. This paper demonstrates the application of rate-distortion theory to two benchmark domains where capacity limits are especially salient in human perception: discrete categorization of stimuli (also known as absolute identification) and visual working memory. A software package written for the R statistical programming language is described that aids in the development of models based on rate-distortion theory.

  19. Statistical characterization of C-arm distortion with application to intra-operative distortion correction

    NASA Astrophysics Data System (ADS)

    Chintalapani, Gouthami; Jain, Ameet K.; Taylor, Russell H.

    2007-03-01

    C-arm images suffer from pose dependant distortion, which needs to be corrected for intra-operative quantitative 3D surgical guidance. Several distortion correction techniques have been proposed in the literature, the current state of art using a dense grid pattern rigidly attached to the detector. These methods become cumbersome for intra-operative use, such as 3D reconstruction, since the grid pattern interferes with patient anatomy. The primary contribution of this paper is a framework to statistically analyze the distortion pattern which enables us to study alternate intra-operative distortion correction methods. In particular, we propose a new phantom that uses very few BBs, and yet accurately corrects for distortion. The high dimensional space of distortion pattern can be effectively characterized by principal component analysis (PCA). The analysis shows that only first three eigen modes are significant and capture about 99% of the variation. Phantom experiments indicate that distortion map can be recovered up to an average accuracy of less than 0.1 mm/pixel with these three modes. With this prior statistical knowledge, a subset of BBs can be sufficient to recover the distortion map accurately. Phantom experiments indicate that as few as 15 BBs can recover distortion with average error of 0.17 mm/pixel, accuracy sufficient for most clinical applications. These BBs can be arranged on the periphery of the C-arm detector, minimizing the interference with patient anatomy and hence allowing the grid to remain attached to the detector permanently. The proposed method is fast, economical, and C-arm independent, potentially boosting the clinical viability of applications such as quantitative 3D fluoroscopic reconstruction.

  20. Fish's Muscles Distortion and Pectoral Fins Propulsion of Lift-Based Mode

    NASA Astrophysics Data System (ADS)

    Yang, S. B.; Han, X. Y.; Qiu, J.

    As a sort of MPF(median and/or paired fin propulsion), pectoral fins propulsion makes fish easier to maneuver than other propulsion, according to the well-established classification scheme proposed by Webb in 1984. Pectoral fins propulsion is classified into oscillatory propulsion, undulatory propulsion and compound propulsion. Pectoral fins oscillatory propulsion, is further ascribable to two modes: drag-based mode and lift-based mode. And fish exhibits strong cruise ability by using lift-based mode. Therefore to robot fish design using pectoral fins lift-based mode will bring a new revolution to resources exploration in blue sea. On the basis of the wave plate theory, a kinematic model of fish’s pectoral fins lift-based mode is established associated with the behaviors of cownose ray (Rhinoptera bonasus) in the present work. In view of the power of fish’s locomotion from muscle distortion, it would be helpful benefit to reveal the mechanism of fish’s locomotion variation dependent on muscles distortion. So this study puts forward the pattern of muscles distortion of pectoral fins according to the character of skeletons and muscles of cownose ray in morphology and simulates the kinematics of lift-based mode using nonlinear analysis software. In the symmetrical fluid field, the model is simulated left-right symmetrically or asymmetrically. The results qualitatively show how muscles distortion determines the performance of fish locomotion. Finally the efficient muscles distortion associated with the preliminary dynamics is induced.

  1. Nonlinear Hysteretic Torsional Waves

    NASA Astrophysics Data System (ADS)

    Cabaret, J.; Béquin, P.; Theocharis, G.; Andreev, V.; Gusev, V. E.; Tournat, V.

    2015-07-01

    We theoretically study and experimentally report the propagation of nonlinear hysteretic torsional pulses in a vertical granular chain made of cm-scale, self-hanged magnetic beads. As predicted by contact mechanics, the torsional coupling between two beads is found to be nonlinear hysteretic. This results in a nonlinear pulse distortion essentially different from the distortion predicted by classical nonlinearities and in a complex dynamic response depending on the history of the wave particle angular velocity. Both are consistent with the predictions of purely hysteretic nonlinear elasticity and the Preisach-Mayergoyz hysteresis model, providing the opportunity to study the phenomenon of nonlinear dynamic hysteresis in the absence of other types of material nonlinearities. The proposed configuration reveals a plethora of interesting phenomena including giant amplitude-dependent attenuation, short-term memory, as well as dispersive properties. Thus, it could find interesting applications in nonlinear wave control devices such as strong amplitude-dependent filters.

  2. Synthesize function for describing distorted 2-D magnetotelluric responses caused by topography

    NASA Astrophysics Data System (ADS)

    Promdee, Ninrat; Sarakorn, Weerachai

    2016-04-01

    In this research, the distortions of 2-D magnetotelluric responses caused by topographies are described by an appropriated synthesize functions. The damping wave equations and the considered topographic curves are used as the kernel of selected synthesize functions. The parameters of those functions are estimated by using the randomized neighborhood search method. The validity of functions is tested on half-space and COMMEMI2D-1 models with cosinusoidal, Gaussian and logistic topographic curves. The obtained results indicate that distorted apparent resistivity are well described by the selected synthesize functions with an acceptable root mean square errors. The obtained values of parameters are varied on both periods of EM wave and height of topographies.

  3. Hybrid functional description of the rhombohedrally distorted B1-structured MnO

    NASA Astrophysics Data System (ADS)

    Franchini, Cesare; Hirshl, Robin; Bayer, Veronika

    2005-03-01

    We report a first principle calculation of the ground state properties of MnO within the plane wave based PBE0 hybrid density functional approach developed on the projector augmented wave scheme VASP (Vienna {ab initio} Simulation Package). The insulating, antiferromagnetically ordered and rhombohedrally distorted B1 structure is found to be the most stable phase, consistent with experiment. The gap (4.02 eV), magnetic moment (4.52 m/B), optimum lattice constant (4.40 A), rhombohedral distortion angle (0.88), density of states, and exchange integrals, are all in good agreement with experiment. Our findings confirm the picture which places MnO in the intermediate charge-transfer/Mott-Hubbard regime and suggest that the parameter-free PBE0 hybrid functional method, combining the full nonlocal exact exchange interaction with the PBE exchange-correlation functional well correct the deficiency of conventional DFT, thus providing a accurate description of this correlated material.

  4. Distortion and broadening of internal solitary wavefront in the northeastern South China Sea deep basin

    NASA Astrophysics Data System (ADS)

    Xie, Jieshuo; He, Yinghui; Lü, Haibin; Chen, Zhiwu; Xu, Jiexin; Cai, Shuqun

    2016-07-01

    Internal solitary waves (ISWs) with peculiar fronts are frequently observed in the world ocean by satellite images, though with quite few explanations. In this study a distorted and broadening ISW front across the northeastern South China Sea deep basin is presented by using synthetic aperture radar (SAR) image. To illustrate this peculiar front, a nonlinear refraction model is developed to simulate and evaluate the effects of realistic bottom topography, current, and stratification on its transformation. Simulated results in realistic oceanic environments show good agreements with this SAR-observed front. Based on separate and comparative results in different background environments, we demonstrate that the distortion is actually caused by the strong mesoscale currents at periphery of an anticyclonic eddy. Moreover, the broadening is due to the difference in change of wave half width at different rays, which is associated with the different transformation of ISWs across variable bottom topography in the deep basin.

  5. JPEG 2000 Encoding with Perceptual Distortion Control

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.; Liu, Zhen; Karam, Lina J.

    2008-01-01

    An alternative approach has been devised for encoding image data in compliance with JPEG 2000, the most recent still-image data-compression standard of the Joint Photographic Experts Group. Heretofore, JPEG 2000 encoding has been implemented by several related schemes classified as rate-based distortion-minimization encoding. In each of these schemes, the end user specifies a desired bit rate and the encoding algorithm strives to attain that rate while minimizing a mean squared error (MSE). While rate-based distortion minimization is appropriate for transmitting data over a limited-bandwidth channel, it is not the best approach for applications in which the perceptual quality of reconstructed images is a major consideration. A better approach for such applications is the present alternative one, denoted perceptual distortion control, in which the encoding algorithm strives to compress data to the lowest bit rate that yields at least a specified level of perceptual image quality. Some additional background information on JPEG 2000 is prerequisite to a meaningful summary of JPEG encoding with perceptual distortion control. The JPEG 2000 encoding process includes two subprocesses known as tier-1 and tier-2 coding. In order to minimize the MSE for the desired bit rate, a rate-distortion- optimization subprocess is introduced between the tier-1 and tier-2 subprocesses. In tier-1 coding, each coding block is independently bit-plane coded from the most-significant-bit (MSB) plane to the least-significant-bit (LSB) plane, using three coding passes (except for the MSB plane, which is coded using only one "clean up" coding pass). For M bit planes, this subprocess involves a total number of (3M - 2) coding passes. An embedded bit stream is then generated for each coding block. Information on the reduction in distortion and the increase in the bit rate associated with each coding pass is collected. This information is then used in a rate-control procedure to determine the

  6. Engaging distortions: are we idealizing marriage?

    PubMed

    Bonds-Raacke, J M; Bearden, E S; Carriere, N J; Anderson, E M; Nicks, S D

    2001-03-01

    The present study was an investigation of the premarital status of engagement in terms of relationship satisfaction and marital expectations using the Evaluation and Nurturing Relationship Issues, Communication and Happiness (ENRICH) Marital Satisfaction Scale (EMS) and its two subscales of Idealistic Distortion (ID) and Marital Satisfaction (MS) (D. G. Fournier, D. H. Olson, & J. M. Druckman, 1983). There were 104 students (23 men and 81 women), of which 15 were married, 19 were engaged, and 70 had extended dating relationships. On average, participants had been in the relationship for 3.8 years, and the mean age was 22 years. Results demonstrated that individuals engaged to be married had significantly higher idealistic distortion scores (M = 86.89) than did either married individuals (M = 56.67) or those in extended dating relationships (M = 61.19). Finally, a negative relation was found between length of relationships and marital satisfaction subscores. Results are discussed in light of factors contributing to such idealized thinking.

  7. Cryogenically cooled monochromator thermal distortion predictions.

    SciTech Connect

    Tajiri, G.; Lee, W.-K.; Fernandez, P.; Mills, D.; Assoufid, L.; Amirouche, F.

    1999-10-29

    Silicon crystal monochromators at cryogenic temperatures have been used with great success at third-generation synchrotrons radiation sources. At the Advanced Photon Source (APS) the unique characteristics of silicon at liquid nitrogen temperatures (77 K) have been leveraged to significantly reduce the thermally induced distortions on beamline optical components. Finite element simulations of the nonlinear (temperature-dependent material properties) thermal stress problem were performed and compared with the experimental measurements. Several critical finite element modeling considerations are discussed for their role in accurately predicting the highly coupled thermal and structural response of the optical component's surface distortion to the high thermal heat flux. Depending on the estimated convection heat transfer coefficient, the final refined finite element model's predictions correlated well with the experimental measurements.

  8. Maternal transmission, sex ratio distortion, and mitochondria

    PubMed Central

    Perlman, Steve J.; Hodson, Christina N.; Hamilton, Phineas T.; Opit, George P.; Gowen, Brent E.

    2015-01-01

    In virtually all multicellular eukaryotes, mitochondria are transmitted exclusively through one parent, usually the mother. In this short review, we discuss some of the major consequences of uniparental transmission of mitochondria, including deleterious effects in males and selection for increased transmission through females. Many of these consequences, particularly sex ratio distortion, have well-studied parallels in other maternally transmitted genetic elements, such as bacterial endosymbionts of arthropods. We also discuss the consequences of linkage between mitochondria and other maternally transmitted genetic elements, including the role of cytonuclear incompatibilities in maintaining polymorphism. Finally, as a case study, we discuss a recently discovered maternally transmitted sex ratio distortion in an insect that is associated with extraordinarily divergent mitochondria. PMID:25870270

  9. Maternal transmission, sex ratio distortion, and mitochondria.

    PubMed

    Perlman, Steve J; Hodson, Christina N; Hamilton, Phineas T; Opit, George P; Gowen, Brent E

    2015-08-18

    In virtually all multicellular eukaryotes, mitochondria are transmitted exclusively through one parent, usually the mother. In this short review, we discuss some of the major consequences of uniparental transmission of mitochondria, including deleterious effects in males and selection for increased transmission through females. Many of these consequences, particularly sex ratio distortion, have well-studied parallels in other maternally transmitted genetic elements, such as bacterial endosymbionts of arthropods. We also discuss the consequences of linkage between mitochondria and other maternally transmitted genetic elements, including the role of cytonuclear incompatibilities in maintaining polymorphism. Finally, as a case study, we discuss a recently discovered maternally transmitted sex ratio distortion in an insect that is associated with extraordinarily divergent mitochondria.

  10. Implicit cognitive distortions and sexual offending.

    PubMed

    Mihailides, Stephen; Devilly, Grant J; Ward, Tony

    2004-10-01

    This work develops and tests the semantic-motivation hypothesis of sexual offenders' implicit cognitions. This hypothesis posits that sexual offenders' cognitive distortions emerge at the interface between implicit motivation and cognition. The semantic-motivation hypothesis is used to guide the development of 3 implicit association tests (IATs). These IATs were used to test for the existence of 3 expected child sexual offender implicit cognitive distortions in child sexual offenders ("children as sexual beings," "uncontrollability of sexuality," and "sexual entitlement-bias"). Results showed that child sexual offenders had larger IAT effects than did mainstream offenders and male and female nonoffenders for the "children as sexual beings" and the "uncontrollability of sexuality" implicit theories. Child sexual offenders also had a larger IAT effect than male and female nonoffenders for the "sexual entitlement-bias" implicit theory. Implications for the semantic-motivation hypothesis are discussed.

  11. Restoration of distorted images, terahertz generation and terahertz interference based on multiple-coupled optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    Ding, Yujie J.

    2015-03-01

    We review our progress made on applications of coupled optical parametric oscillators based on a composite consisting of adhesive-free-bonded KTiOPO4 stacks. By using the phase- conjugate output generated by the composite, we have demonstrated that the spatial profile after the beam propagates through the phase-distorted medium can be restored to the profile before the distortion. In addition, we have restored the images being blurred by the phase distortion. We have efficiently generated terahertz outputs by mixing the idler twins from the coupled optical parametric oscillators. By using the alternatively-rotated GaP plates as an output coupler for the coupled optical parametric oscillators, we have efficiently generated terahertz waves based on an intracavity configuration. By placing both the composite and a bulk KTiOPO4 crystal in the same cavity, we have demonstrated the interference effect of the THz waves generated by using different pairs of the optical beams.

  12. Body image distortions in healthy adults.

    PubMed

    Fuentes, Christina T; Longo, Matthew R; Haggard, Patrick

    2013-10-01

    Distortions of body image have often been investigated in clinical disorders. Much of this literature implicitly assumes healthy adults maintain an accurate body image. We recently developed a novel, implicit, and quantitative measure of body image - the Body Image Task (BIT). Here, we report a large-scale analysis of performance on this task by healthy adults. In both an in-person and an online version of the BIT, participants were presented with an image of a head as an anchoring stimulus on a computer screen, and told to imagine that the head was part of a mirror image of themselves in a standing position. They were then instructed to judge where, relative to the head, each of several parts of their body would be located. The relative positions of each landmark can be used to construct an implicit perceptual map of bodily structure. We could thus measure the internally-stored body image, although we cannot exclude contributions from other representations. Our results show several distortions of body image. First, we found a large and systematic over-estimation of width relative to height. These distortions were similar for both males and females, and did not closely track the idiosyncrasies of individual participant's own bodies. Comparisons of individual body parts showed that participants overestimated the width of their shoulders and the length of their upper arms, relative to their height, while underestimating the lengths of their lower arms and legs. Principal components analysis showed a clear spatial structure to the distortions, suggesting spatial organisation and segmentation of the body image into upper and lower limb components that are bilaterally integrated. These results provide new insight into the body image of healthy adults, and have implications for the study and rehabilitation of clinical populations.

  13. Rapid Distortion Theory in astrophysical turbulence

    NASA Astrophysics Data System (ADS)

    Safonov, Sergey; Petrosyan, Arakel

    2016-04-01

    In this report, we study statistical properties of astrophysical turbulent plasma flows using Rapid Distortion Theory (RDT). The core assumption is that the turbulence responds to the external distortion so fast, that inertial and viscous forces result in a negligible change in velocity distribution. Thus it is assumed that the response to the external effect takes place in the time interval much smaller than turbulence decay time. This allows to linearize equations and to derive equations for second moments of turbulence. We apply RDT to incompressible turbulent MHD flows distorted with external magnetic field and linear velocity shear in cases of rotating and non-rotating plasma. It is shown that even with a strong nonlinearity many properties of turbulence can be qualitatively studied using a linear theory. A closed system of linear equations for velocity and magnetic field fluctuations is derived. Development of initially isotropic turbulence and transition to anisotropy are studied. Equations for fluid, current and cross helicity are derived. Differences in cases of rotating and non-rotating flows are discussed. Changes introduced by considering Hall effect are discussed.

  14. Low Distortion Welded Joints for NCSX

    SciTech Connect

    M. Denault, M Viola, W. England

    2009-02-19

    The National Compact Stellarator Experiment (NCSX) required precise positioning of the field coils in order to generate suitable magnetic fields. A set of three modular field coils were assembled to form the Half Field-Period Assemblies (HPA). Final assembly of the HPA required a welded shear plate to join individual coils in the nose region due to the geometric limitations and the strength constraints. Each of the modular coil windings was wound on a stainless steel alloy (Stellalloy) casting. The alloy is similar to austenitic 316 stainless steel. During the initial welding trials, severe distortion, of approximately 1/16", was observed in the joint caused by weld shrinkage. The distortion was well outside the requirements of the design. Solutions were attempted through several simultaneous routes. The joint design was modified, welding processes were changed, and specialized heat reduction techniques were utilized. A final joint design was selected to reduce the amount of weld material needed to be deposited, while maintaining adequate penetration and strength. Several welding processes and techniques using Miller Axcess equipment were utilized that significantly reduced heat input. The final assembly of the HPA was successful. Distortion was controlled to 0.012", well within the acceptable design tolerance range of 0.020" over a 3.5 foot length.

  15. Distortion of conformal antennas on aircraft structures

    NASA Astrophysics Data System (ADS)

    Schippers, Harmen; van Tongeren, Hans; Verpoorte, Jaco; Vos, Guus

    2001-08-01

    Conformal antennas on aircraft allow the use of non-conventional antenna locations such as the skin of the aircraft. However, when antennas are installed at these locations they are subject to steady and unsteady aerodynamic loads. The inertial forces and these aerodynamic loads will cause deformations and vibrations of the total antenna surface. The effect of these distortions on antenna performance will be most significant on highly directional antennas. The aim of the present paper is to describe technology development for estimating the effects of surface distortion on antenna performance. The technology is applied to a Side-Looking Airborne Radar (SLAR) antenna on a reconnaissance pod mounted on a fighter type aircraft. This generic SLAR antenna is a phased array antenna covering two faces of the pod: one part on the vertical side face and one part on the lower face of the pod. Radiation patterns are computed for distorted antenna surfaces. The computational model for the determination of the disturbed radiation pattern is based on geometrical parameterisation of the Stratton-Chu integral equations.

  16. Tree encoding for symmetric sources with a distortion measure

    NASA Technical Reports Server (NTRS)

    Gallager, R. G.

    1974-01-01

    A simple algorithm is developed for mapping the outputs of a source into a set of code sequences generated by a tree code. The algorithm is analyzed for the case of a source producing discrete independent equiprobable letters when the distortion measure satisfies a certain symmetry condition. It is shown that the algorithm is capable of achieving an average distortion as close as desired to the minimum average distortion for the code rate given by Shannon's rate-distortion theorem.

  17. Perceptual and Conceptual Distortions of Implicit Hand Maps

    PubMed Central

    Longo, Matthew R.; Mattioni, Stefania; Ganea, Nataşa

    2015-01-01

    Recent studies have revealed that human position sense relies on a massively distorted representation of hand size and shape. By comparing the judged location of landmarks on an occluded hand, Longo and Haggard (2010) constructed implicit perceptual maps of represented hand structure, showing large underestimation of finger length and overestimation of hand width. Here, we investigated the contribution of two potential sources of distortions to such effects: perceptual distortions reflecting spatial warping of the representation of bodily tissue itself, perhaps reflecting distortions of somatotopic cortical maps, and conceptual distortions reflecting mistaken beliefs about the locations of different landmarks within the body. In Experiment 1 we compared distorted hand maps to a task in which participants explicitly judged the location of their knuckles in a hand silhouette. The results revealed the conceptual distortions are responsible for at least part of the underestimation of finger length, but cannot explain overestimation of hand width. Experiment 2 compared distortions of the participant’s own hand based on position sense with a prosthetic hand based on visual memory. Underestimation of finger length was found for both hands, providing further evidence that it reflects a conceptual distortion. In contrast, overestimation of hand width was specific to representation of the participant’s own hand, confirming it reflects a perceptual distortion. Together, these results suggest that distorted body representations do not reflect a single underlying cause. Rather, both perceptual and conceptual distortions contribute to the overall configuration of the hand representation. PMID:26733842

  18. Correction of nonlinear lateral distortions of scanning probe microscopy images.

    PubMed

    Schnedler, M; Weidlich, P H; Portz, V; Weber, D; Dunin-Borkowski, R E; Ebert, Ph

    2014-01-01

    A methodology for the correction of scanning probe microscopy image distortions is demonstrated. It is based on the determination of displacement vectors from the measurement of a calibration sample. By moving the pixels of the distorted scanning probe microscopy image along the displacement vectors an almost complete correction of the nonlinear, time independent distortions is achieved. PMID:24013615

  19. The Perceptual Distortion of Height in Intercollegiate Debate.

    ERIC Educational Resources Information Center

    Hensley, Wayne E.; Angoli, Marilyn

    Both balance and reinforcement theories were used in an examination of the perceptual distortion of height among 146 college debaters. Balance theory predicted that losers would distort winners' heights upward; reinforcement theory predicted that winners would distort losers' heights upward. The results confirmed both predictions. The possibility…

  20. Cognitive Distortions and Autonomy among Chinese University Students

    ERIC Educational Resources Information Center

    Zhang, Li-fang

    2008-01-01

    The purpose of this study was to examine the roles of university students' cognitive distortions in their sense of autonomy. One hundred and three third-year university students from Shanghai, The People's Republic of China, responded to the Cognitive Distortion Scales [Briere, J. (2000). "Cognitive Distortion Scales: Professional manual". Lutz,…

  1. Appraisal Distortions and Intimate Partner Violence: Gender, Power, and Interaction

    ERIC Educational Resources Information Center

    Whiting, Jason B.; Oka, Megan; Fife, Stephen T.

    2012-01-01

    In relationships characterized by control, abuse, or violence, many appraisal distortions occur including denial and minimization. However, the nature of the distortion varies depending on the individual's role in the relationship (i.e., abuser or victim). Reducing these distortions is an important component in treatment success and involves…

  2. The Generation of Harmonic Distortion and Distortion Products in a Computational Model of the Cochlea

    NASA Astrophysics Data System (ADS)

    Meaud, Julien; Li, Yizeng; Grosh, Karl

    2011-11-01

    It is generally agreed that the nonlinear response of the cochlea is due to the forward transduction of the outer hair cell (OHC) hair bundle (HB) and subsequent alteration of the active force applied to the cochlear structures, including the basilar membrane (BM). A mechanical-acoustical-electrical model of the cochlea with three-dimensional fluid representation, and feedback from OHC somatic motility coupled to nonlinear HB mechanotransduction is used to predict nonlinear distortion of the BM response to acoustic stimulus. An efficient alternating frequency time scheme is implemented to solve for the nonlinear stationary dynamics of the cochlea. The model is used to predict the location of maximum generation of nonlinear distortion during pure tone and two-tone stimulation as well as the propagation of the distortion components on the BM.

  3. Flow distortion at a dense forest edge

    NASA Astrophysics Data System (ADS)

    Dellwik, E.; Mann, J.

    2012-12-01

    Results from a forest edge experiment with two masts and one horizontally pointed wind lidar are presented. The experiment was performed at a dense beech forest edge of the Tromnæs forest, which is a 24m tall mature beech forest on the island Falster, Denmark. The topography at the site is flat. The masts were placed approximately 1.5 canopy heights upwind and downwind of the edge and are two canopy heights tall. We present data showing how the forest edge distorts the flow when the flow is perpendicular to the edge and towards the forest during near-neutral atmospheric stratification. Despite that the wind gradient above the canopy is similar before and after the edge, the momentum flux is strongly reduced above the canopy. This result is especially pronounced during summer and high leaf area index, when the momentum flux was slightly positive 1.2 canopy heights above ground level. This is contrary to the results by standard Reynolds' averaged Navier Stokes models that predict an overshoot of the momentum flux. Further above the forest, the total amount of turbulent kinetic energy remained constant compared to the upwind measurements. A reduction of the vertical variance of the flow was largely compensated by an increase in the lateral variance, whereas the streamwise variance remained approximately constant. This result is in contrast to the predictions by homogeneous rapid distortion theory. We apply and develop an alternative framework based on inhomogeneous rapid distortion theory in combination with the turbulence model by Mann (1994), which can predict the observed changes of the flow. The inhomogeneous rapid distortion theory takes the blocking of the flow by the top of the canopy into account. This effect turns out to suppress the vertical momentum flux drastically and redistribute the vertical fluctuations into the lateral direction. We show one- and two-point spectra for verification of the model. The results are relevant for understanding the on

  4. Redshift distortions of galaxy correlation functions

    NASA Technical Reports Server (NTRS)

    Fry, J. N.; Gaztanaga, Enrique

    1994-01-01

    To examine how peculiar velocities can affect the two-, three-, and four-point redshift correlation functions, we evaluate volume-average correlations for configurations that emphasize and minimize redshift distortions for four different volume-limited samples from each of the CfA, SSRS, and IRAS redshift catalogs. We present the results as the correlation length r(sub 0) and power index gamma of the two-point correlations, bar-xi(sub 0) = (r(sub 0)/r)(exp gamma), and as the hierarchical amplitudes of the three- and four-point functions, S(sub 3) = bar-xi(sub 3)/bar-xi(exp 2)(sub 2) and S(sub 4) = bar-xi(sub 4)/bar-xi(exp 3)(sub 2). We find a characteristic distortion for bar-xi(sub 2), the slope gamma is flatter and the correlation length is larger in redshift space than in real space; that is, redshift distortions 'move' correlations from small to large scales. At the largest scales (up to 12 Mpc), the extra power in the redshift distribution is compatible with Omega(exp 4/7)/b approximately equal to 1. We estimate Omega(exp 4/7)/b to be 0.53 +/- 0.15, 1.10 +/- 0.16, and 0.84 +/- 0.45 for the CfA, SSRS, and IRAS catalogs. Higher order correlations bar-xi(sub 3) and bar-xi(sub 4) suffer similar redshift distortions but in such a way that, within the accuracy of our ananlysis, the normalized amplitudes S(sub 3) and S(sub 4) are insensitive to this effect. The hierarchical amplitudes S(sub 3) and S(sub 4) are constant as a function of scale between 1 and 12 Mpc and have similar values in all samples and catalogs, S(sub 3) approximately equal to 2 and S(sub 4) approximately equal to 6, despite the fact that bar-xi(sub 2), bar-xi(sub 3), and bar-xi(sub 4) differ from one sample to another by large factors (up to a factor of 4 in bar-xi(sub 2), 8 for bar-xi(sub 3), and 12 for bar-xi(sub 4)). The agreement between the independent estimations of S(sub 3) and S(sub 4) is remarkable given the different criteria in the selection of galaxies and also the difference in the

  5. Potential-well distortion in barrier Rf

    SciTech Connect

    King Ng

    2004-04-29

    Head-tail asymmetry has been observed in the longitudinal beam profiles in the Fermilab Recycler Ring where protons or antiprotons are stored in rf barrier buckets. The asymmetry is caused by the distortion of the rf potential well in the presence of resistive impedance. Gaussian energy distribution can fit the observed asymmetric beam profile but not without discrepancy. It can also fit the measured energy distribution. On the other hand, generalized elliptic distribution gives a better fit to the beam profile. However, it fails to reproduce the observed energy distribution.

  6. Thermal cycling distortion of metal ceramics: Part II--Etiology.

    PubMed

    Campbell, S D; Pelletier, L B

    1992-08-01

    The three-dimensional geometry of conventional fixed prostheses complicates the study of the thermal cycling distortion in metal ceramic alloys. Any explanation of the etiology of thermal cycling distortion in metal ceramic restorations must account for the observed magnitude, timing, and direction of the deformation. The simplified experimental geometry developed in Part I was applied to elucidate the etiologic factors involved in metal ceramic deformation. Techniques to minimize the thermal cycling distortion were also studied. It was found that all of the significant distortion occurred during the first thermal cycling of the alloy (oxidation) and that no distortion resulted from the application of body porcelain. The specimens that were cold worked and then oxidized had significantly more distortion than any other group. A significant reduction in distortion was observed when the initial thermal cycling was completed before the specimens were cold worked. It was determined that the release of casting- and cold working-induced stresses had a synergistic effect. PMID:1501176

  7. Frequency shifts in distortion-product otoacoustic emissions evoked by swept tones.

    PubMed

    Shera, Christopher A; Abdala, Carolina

    2016-08-01

    When distortion-product otoacoustic emissions (DPOAEs) are evoked using stimuli whose instantaneous frequencies change rapidly and continuously with time (swept tones), the oscillatory interference pattern known as distortion-product fine structure shifts slightly along the frequency axis in the same direction as the sweep. By analogy with the temporal mechanisms thought to underlie the differing efficacies of up- and down-swept stimuli as perceptual maskers (e.g., Schroeder-phase complexes), fine-structure shifts have been ascribed to the phase distortion associated with dispersive wave propagation in the cochlea. This paper tests an alternative hypothesis and finds that the observed shifts arise predominantly as a methodological side effect of the analysis procedures commonly used to extract delayed emissions from the measured time waveform. Approximate expressions for the frequency shifts of DPOAE distortion and reflection components are derived, validated with computer simulations, and applied to account for DPOAE fine-structure shifts measured in human subjects. Component magnitudes are shown to shift twice as much as component phases. Procedures for compensating swept-tone measurements to obtain estimates of the total DPOAE and its components measured at other sweep rates or in the sinusoidal steady state are presented. PMID:27586726

  8. Visualization of Merging Black Holes and Gravitational Waves

    NASA Video Gallery

    This visualization shows gravitational waves emitted by two black holes of nearly equal mass as they spiral together and merge. Orange ripples represent distortions of space-time caused by the rapi...

  9. Reducing Field Distortion in Magnetic Resonance Imaging

    NASA Technical Reports Server (NTRS)

    Eom, Byeong Ho; Penanen, Konstantin; Hahn, Inseob

    2010-01-01

    A concept for a magnetic resonance imaging (MRI) system that would utilize a relatively weak magnetic field provides for several design features that differ significantly from the corresponding features of conventional MRI systems. Notable among these features are a magnetic-field configuration that reduces (relative to the conventional configuration) distortion and blurring of the image, the use of a superconducting quantum interference device (SQUID) magnetometer as the detector, and an imaging procedure suited for the unconventional field configuration and sensor. In a typical application of MRI, a radio-frequency pulse is used to excite precession of the magnetic moments of protons in an applied magnetic field, and the decaying precession is detected for a short time following the pulse. The precession occurs at a resonance frequency proportional to the strengths of the magnetic field and the proton magnetic moment. The magnetic field is configured to vary with position in a known way; hence, by virtue of the aforesaid proportionality, the resonance frequency varies with position in a known way. In other words, position is encoded as resonance frequency. MRI using magnetic fields weaker than those of conventional MRI offers several advantages, including cheaper and smaller equipment, greater compatibility with metallic objects, and higher image quality because of low susceptibility distortion and enhanced spin-lattice-relaxation- time contrast. SQUID MRI is being developed into a practical MRI method for applied magnetic flux densities of the order of only 100 T

  10. Prediction of Part Distortion in Die Casting

    SciTech Connect

    R. Allen Miller

    2005-03-30

    The die casting process is one of the net shape manufacturing techniques and is widely used to produce high production castings with tight tolerances for many industries. An understanding of the stress distribution and the deformation pattern of parts produced by die casting will result in less deviation from the part design specification, a better die design and eventually more productivity and cost savings. This report presents methods that can be used to simulate the die casting process in order to predict the deformation and stresses in the produced part and assesses the degree to which distortion modeling is practical for die casting at the current time. A coupled thermal-mechanical finite elements model was used to simulate the die casting process. The simulation models the effect of thermal and mechanical interaction between the casting and the die. It also includes the temperature dependant material properties of the casting. Based on a designed experiment, a sensitivity analysis was conducted on the model to investigate the effect of key factors. These factors include the casting material model, material properties and thermal interaction between casting and dies. To verify the casting distortion predictions, it was compared against the measured dimensions of produced parts. The comparison included dimensions along and across the parting plane and the flatness of one surface.

  11. Distorted Coulomb field of the scattered electron

    SciTech Connect

    Thomsen, H. D.; Esberg, J.; Andersen, K. K.; Lund, M. D.; Knudsen, H.; Uggerhoej, U. I.; Sona, P.; Mangiarotti, A.; Ketel, T. J.; Dizdar, A.; Ballestrero, S.; Connell, S. H.

    2010-03-01

    Experimental results for the radiation emission from ultrarelativistic electrons in targets of 0.03%-5% radiation length is presented. For the thinnest targets, the radiation emission is in accordance with the Bethe-Heitler formulation of bremsstrahlung, the target acting as a single scatterer. In this regime, the radiation intensity is proportional to the thickness. As the thickness increases, the distorted Coulomb field of the electron that is the result of the first scattering events, leads to a suppressed radiation emission per interaction, upon subsequent scattering events. In that case, the radiation intensity becomes proportional to a logarithmic function of the thickness, due to the suppression. Eventually, once the target becomes sufficiently thick, the entire radiation process becomes influenced by multiple scattering and the radiation intensity is again proportional to the thickness, but with a different constant of proportionality. The observed logarithmic thickness dependence of radiation intensity at intermediate values of the thickness can be directly interpreted as a manifestation of the distortion of the electron Coulomb field resulting from a scattering event. The Landau-Pomeranchuk-Migdal effect is explored with high primary energy using materials with low nuclear charge (Z). Also, targets that should give rise to the claimed interference effect in high-energy radiation emission from a structured target of thin foils are investigated.

  12. Nonrenewable resources, fiscal distortions, and risk effects

    SciTech Connect

    Wingate, S.R.

    1988-01-01

    Fiscal systems applied to resource-development projects serve not only to distribute ex post rents between the firm and government, but also to distribute project risk between the parties. Further, when fiscally induced distortions in firm behavior are present, fiscal systems influence the probability of project payouts and thus the risk characteristics of the project. This study provides a framework in which alternative fiscal systems may be evaluated with attention paid jointly to fiscal distortions, risk sharing, and fiscal risk effects. The framework is based on firms and a government that are self-interested and risk-averse, but allows for evaluation of alternative fiscal systems from the perspective of an altruistic risk-averse social planner. Specification of preference functions of the firms and government beyond strict concavity (risk aversion) is avoided by use of the concept of second-degree stochastic dominance. Application of the framework is illustrated by consideration of operating profit and gross revenue taxes within a model of oil-pool development. In simulations of the model, both the operating profits and gross revenue taxes are fond to increase project risk when judged from a social perspective and against a benchmark risk-preserving tax; and the profit tax is riskier than the revenue tax.

  13. Design of the new rigid endoscope distortion measurement system

    NASA Astrophysics Data System (ADS)

    Zhai, Xiaohao; Liu, Xiaohua; Liu, Ming; Hui, Mei; Dong, Liquan; Zhao, Yuejin; Wang, Yakun; Li, Yonghui; Zhou, Peng

    2015-08-01

    Endoscopic imaging quality affects industrial safety and medical security. Rigid endoscope distortion is of great signification as one of optical parameters to evaluate the imaging quality. This paper introduces a new method of rigid endoscope distortion measurement, which is different from the common methods with low accuracy and fussy operation. It contains a Liquid Crystal Display (LCD) to display the target, a CCD to obtain the images with distortion, and a computer to process the images. The LCD is employed instead of common white screen. The autonomous control system of LCD makes it showing the test target designed for distortion, and its parameter is known. LCD control system can change the test target to satisfy the different demand for accuracy, which avoids replacing target frequently. The test system also contains a CCD to acquire images in the exit pupil position of rigid endoscope. Rigid endoscope distortion is regarded as centrosymmetric, and the MATLAB software automatically measures it by processing the images from CCD. The MATLAB software compares target images with that without distortion on LCD and calculates the results. Relative distortion is obtained at different field of view (FOV) radius. The computer plots the curve of relative distortion, abscissa means radius of FOV, ordinate means relative distortion. The industry standard shows that, the distortion at 70% field of view is pointed on the curve, which can be taken as an evaluation standard. This new measuring method achieves advantages of high precision, high degree of intelligence, excellent repeatability and gets calculation results quickly.

  14. Centrifugal Distortion Causes Anderson Localization in Laser Kicked Molecules

    NASA Astrophysics Data System (ADS)

    Floss, Johannes; Averbukh, Ilya Sh.

    2014-05-01

    The periodically kicked 2D rotor is a textbook model in nonlinear dynamics. The classical kicked rotor can exhibit truly chaotic motion, whilst in the quantum regime this chaotic motion is suppressed by a mechanism similar to Anderson Localization. Up to now, these effects have been mainly observed in an atom optics analogue of a quantum rotor: cold atoms in a standing light wave. We demonstrate that common linear molecules (like N2, O2, CO2, ...), kicked by a train of short linearly polarized laser pulses, can exhibit a new mechanism for dynamical Anderson Localization due to their non-rigidity. When the pulses are separated by the rotational revival time trev = πℏ / B , the angular momentum J grows ballistically (Quantum Resonance). We show that, due to the centrifugal distortion of fast spinning molecules, above some critical value J =Jcr the Quantum Resonance is suppressed via the mechanism of Anderson Localization. This leads to a non-sinusoidal oscillation of the angular momentum distribution, which may be experimentally observed even at ambient conditions by using current techniques for laser molecular alignment.

  15. Distortion of surface plasmon polariton propagation on graphene due to chemical potential variation

    NASA Astrophysics Data System (ADS)

    Amanatiadis, Stamatios; Kantartzis, Nikolaos

    2016-04-01

    The variation of graphene chemical potential owing to surface plasmon polariton excitation and its influence on the propagation properties of the latter is systematically examined in this paper. Although the chemical potential is controlled via a constant electric field bias, the excitation of the highly confined surface wave can considerably affect it, thus disrupting the wave natural propagation. To this aim, the propagation properties of the surface wave are extracted to reliably estimate the aforesaid distortion effect with regard to frequency. Numerical results, obtained in terms of an accurate finite-difference time-domain scheme, certify this interesting convention. Furthermore, the electrodynamic forces on the free electrons of the graphene layer are calculated to justify the electrostatic assumption.

  16. Thermal-induced two dimensional beam distortion in planar waveguide amplifiers.

    PubMed

    Wang, Xiao-Jun; Ke, Wei-Wei; Su, Hua

    2013-07-29

    Mode characteristics in the solid-state planar waveguide (PWG) laser amplifiers are investigated theoretically, in consideration of the temperature gradient generated by cooling across the thickness and by pumping inhomogeneity along the width direction. When variation of the refractive index along the width direction is dominated by the lower spatial frequencies, the vector wave equation is solved analytically by means of the perturbation method. It is similar to the zigzag slab amplifier in which the phase aberration depending on the width coordinate plays the most important role to cause degradation of the beam quality. The crossing mode distortions owing to two dimension nature of the index variations are illustrated, and that mode profile is varied by the index variation along both the thickness and the width directions. Modes in the single-mode or the few-mode PWGs are shown to suffer weaker thermal-induced distortion across the thickness than those in the multi-mode PWGs.

  17. Primordial trispectra and CMB spectral distortions

    NASA Astrophysics Data System (ADS)

    Bartolo, Nicola; Liguori, Michele; Shiraishi, Maresuke

    2016-03-01

    We study the TTμ bispectrum, generated by correlations between Cosmic Microwave Background temperature (T) anisotropies and chemical potential (μ) distortions, and we analyze its dependence on primordial local trispectrum parameters gNL and τNL. We cross-check our results by comparing the full bispectrum calculation with the expectations from a general physical argument, based on predicting the shape of μ-T correlations from the couplings between short and long perturbation modes induced by primordial non-Gaussianity. We show that both gNL and τNL-parts of the primordial trispectrum source a non-vanishing TTμ signal, contrary to the μμ auto-correlation function, which is sensitive only to the τNL-component. A simple Fisher matrix-based forecast shows that a futuristic, cosmic-variance dominated experiment could in principle detect gNL ~ 0.4 and τNL ~ 40 using TTμ.

  18. Distortions in memory for visual displays

    NASA Technical Reports Server (NTRS)

    Tversky, Barbara

    1989-01-01

    Systematic errors in perception and memory present a challenge to theories of perception and memory and to applied psychologists interested in overcoming them as well. A number of systematic errors in memory for maps and graphs are reviewed, and they are accounted for by an analysis of the perceptual processing presumed to occur in comprehension of maps and graphs. Visual stimuli, like verbal stimuli, are organized in comprehension and memory. For visual stimuli, the organization is a consequence of perceptual processing, which is bottom-up or data-driven in its earlier stages, but top-down and affected by conceptual knowledge later on. Segregation of figure from ground is an early process, and figure recognition later; for both, symmetry is a rapidly detected and ecologically valid cue. Once isolated, figures are organized relative to one another and relative to a frame of reference. Both perceptual (e.g., salience) and conceptual factors (e.g., significance) seem likely to affect selection of a reference frame. Consistent with the analysis, subjects perceived and remembered curves in graphs and rivers in maps as more symmetric than they actually were. Symmetry, useful for detecting and recognizing figures, distorts map and graph figures alike. Top-down processes also seem to operate in that calling attention to the symmetry vs. asymmetry of a slightly asymmetric curve yielded memory errors in the direction of the description. Conceptual frame of reference effects were demonstrated in memory for lines embedded in graphs. In earlier work, the orientation of map figures was distorted in memory toward horizontal or vertical. In recent work, graph lines, but not map lines, were remembered as closer to an imaginary 45 deg line than they had been. Reference frames are determined by both perceptual and conceptual factors, leading to selection of the canonical axes as a reference frame in maps, but selection of the imaginary 45 deg as a reference frame in graphs.

  19. Optimized vector quantization with fuzzy distortion measure

    NASA Astrophysics Data System (ADS)

    Mitra, Sunanda; Pemmaraju, Suryalakshmi

    1996-06-01

    From the perspective of information theory, the design of vector quantizers (VQs) in optimizing the rate distortion function has been extensively studied. In practice, however, the existing VQ algorithms, often, suffer from a number of serious problems, e.g., long search process, codebook initialization, and getting trapped in local minima, inherent to most iterative processes. The generalized Lloyd algorithm, for designing VQs with embedded k-means clustering for codebook generation has been recently used by a number of researcher for efficient image coding by quantizing wavelet decomposed subimages. We present a new approach to vector quantization by generating such multiresolution codebooks using two different neuro-fuzzy clustering techniques that eliminate the existing problems. These clustering techniques integrate fuzzy optimization constraints from the fuzzy-C-means with self-organizing neural network architectures. In one of the new clustering techniques, a new distance measure has also been introduced. The resulting multiresolution codebooks generated from the wavelet decomposed images yield significant improvement in the coding process. The signal transformation and vector quantization stages together yield, at least, 64:1 bit rate reduction with good visual quality and acceptable peak signal to noise ratio (PSNR) and mean square error (MSE). Additional bit rate reduction can be easily obtained by employing conventional entropy encoding after the quantization stage. The performance of this new VQ coding technique has been compared to that of the well-known Linde, Buzo, and Gray (LBG) - VQ for a variety of image classes. The new VQ technique demonstrated superior ability for fast convergence with minimum distortion at similar bit rate reduction then the existing VQ technique for several classes of images/signals including standard test images and medical images in terms of mean-squared error (MSE), peak-signal-to- noise-ratio (PSNR), and visual quality.

  20. The measurement of distortion: theoretical considerations.

    PubMed

    Nicholls, J I

    1977-05-01

    When very find measurements are recorded for the purpose of establishing distortion values, from the standpoint of accuracy, specific procedures must be developed. In the procedural system defined here, a potential major source of error is indicated and the means of overcoming this error established. From the standpoint of modern electronic technology, the use of an analogue-to-digital interface with a digital computer is considered extremely advantageous and allows the utilization of technical help to carry out the preliminary measurements. Under these circumstances, major error sources, such as reader error and calculation error, are eliminated. Further, multiple readings on each point can be made without significant sacrifice of time. This latter statement can help define the reading accuracy on each point and allows an immediate further set of readings on any point that has a large variation in the initially established set of readings. The applicability of this approach to any system in which an accurate set of readings is required to define distortion or some other parameter is limited only by the imagination of the investigator. Measuring points can be established at any desired location, and the number required is a function of the mathematical analysis being attempted. The use of a digital computer to compute the final values allows an immediate remeasurement of the initial values if necessary, since the computer response time is of the order of seconds for the calculations carried out. This is very important if changes in the experimental setup are likely to occur with time. In general, a computerized scheme such as is proposed here allows the investigator to concentrate on the experiment rather than the calculation of results. Also, the use of technical help to carry out delicate measuring procedures can allow the investigator more time to analyze the final results.

  1. Radial line method for rear-view mirror distortion detection

    NASA Astrophysics Data System (ADS)

    Rahmah, Fitri; Kusumawardhani, Apriani; Setijono, Heru; Hatta, Agus M.; Irwansyah, .

    2015-01-01

    An image of the object can be distorted due to a defect in a mirror. A rear-view mirror is an important component for the vehicle safety. One of standard parameters of the rear-view mirror is a distortion factor. This paper presents a radial line method for distortion detection of the rear-view mirror. The rear-view mirror was tested for the distortion detection by using a system consisting of a webcam sensor and an image-processing unit. In the image-processing unit, the captured image from the webcam were pre-processed by using smoothing and sharpening techniques and then a radial line method was used to define the distortion factor. It was demonstrated successfully that the radial line method could be used to define the distortion factor. This detection system is useful to be implemented such as in Indonesian's automotive component industry while the manual inspection still be used.

  2. Global and Local Distortion Inference During Embedded Zerotree Wavelet Decompression

    NASA Technical Reports Server (NTRS)

    Huber, A. Kris; Budge, Scott E.

    1996-01-01

    This paper presents algorithms for inferring global and spatially local estimates of the squared-error distortion measures for the Embedded Zerotree Wavelet (EZW) image compression algorithm. All distortion estimates are obtained at the decoder without significantly compromising EZW's rate-distortion performance. Two methods are given for propagating distortion estimates from the wavelet domain to the spatial domain, thus giving individual estimates of distortion for each pixel of the decompressed image. These local distortion estimates seem to provide only slight improvement in the statistical characterization of EZW compression error relative to the global measure, unless actual squared errors are propagated. However, they provide qualitative information about the asymptotic nature of the error that may be helpful in wavelet filter selection for low bit rate applications.

  3. Numerical and Test Investigation on an Aircraft Inlet Distortion

    NASA Astrophysics Data System (ADS)

    Zhang, Zhang; Hou, Anping; Chen, Yinxiu; Tuo, Wei; Xia, Aiguo

    2013-09-01

    Subscale wind tunnel test of an aircraft vehicle is performed at different Mach number, mass-flow and angle of attack. CFD model, corrected by test results, is also presented to predict inlet performance and total pressure distortion. The result shows total pressure recovery decreases and distortion level rises when Mach number increases from subsonic to supersonic speed, AOA is negative and mass-flow value is too large or too small. Compared linear interpolation based on test result of discrete probes, numerical simulation has advantages in showing inlet flow field predicting actual surface distortion level in AIP plane. Swirl distortion is induced by vortex near the fuselage and adjustable ramp and can strengthen total pressure distortion in AIP at negative AOA. And appropriate suction mass-flow coefficient (1.7% to 3%) is beneficial for inlet performance and total pressure distortion control.

  4. Fundamental studies on welding-induced distortion in thin plates

    NASA Astrophysics Data System (ADS)

    Han, Myoung Soo

    2002-09-01

    Welding of thin plates can cause extensive angular and buckling distortions that deteriorate structural integrity and production reliability. Remarkable developments in computer technology in recent years have improved numerical prediction capability of welding distortion. Despite of many uncertainties in the distortion mechanism, it is generally agreed that welding distortion is predictable if one can approximate the inherent strains distributed in and around the weld region. In this dissertation, a fundamental study on the prediction and the control of welding-induced distortion in thin plates was conducted through correlating inherent strains with welding process variables and the degree of constraints. Experimental studies were also performed to verify the numerical procedure for welding distortion analyses. Significant findings observed through the study are summarized as follows: (1) The peak temperatures and the nil-plasticity peak temperature uniquely determined magnitudes of longitudinal inherent strains. (2) The effective inherent strain responsible for angular distortion was produced under non-uniform temperature distribution through the thickness, and estimated by adding halves of longitudinal plastic strains to transverse inherent strains. (3) The shrinkage volume model considering effective inherent strains reasonably predicted magnitudes of angular distortion. (4) The onset of longitudinal distortion was strongly influenced by transient temperature fields. The more intensified thermal field was required for the onset in the smaller plate subjected to the smaller heat input. Longitudinal distortion in small plates grew for a limited cooling period, and it in large plates continued to grow until the completion of the cooling cycle. (5) The critical curve from eigenvalue analyses showed that the buckling instability is manifested as plate size or heat input increases. Buckling instability predicted by eigenvalue analyses is closely related to the

  5. Analog computer implementation of four instantaneous distortion indices

    NASA Technical Reports Server (NTRS)

    Costakis, W. G.

    1974-01-01

    Dynamic distortion data obtained from inlet engine compatibility test on a J85-GE-13 engine are used to establish the feasibility of using on-line generated indices as control signals. These data are analyzed over time increments of 1.3 seconds on an analog computer. The analog program of four instantaneous distortion indices and their results are presented. A modified approach in determining the extent of distortion is also presented.

  6. Investigating the Origin of Upper-Side-Band Distortion-Product Otoacoustic Emissions within a Micromechanical Cochlear Model

    NASA Astrophysics Data System (ADS)

    Young, J.; Elliott, S. J.; Lineton, B.

    2011-11-01

    Upper-side-band distortion-product otoacoustic emissions (DPOAEs) have a higher frequency than either of the stimulus tones (f1 and f2). They are less widely used in clinical practice and their generation is more difficult to understand in comparison to lower side band DPOAEs. We have developed a numerical quasilinear model of the cochlea based on the work of Kanis and de Boer. The model is applied to investigate the source of the 2f2-f1 upper-side-band DPOAE using several complementary approaches, including a novel method of decomposing the predicted cochlear response into forward and backward travelling waves. We conclude that the simulated 2f2-f1 distortion product (DP) consists of contributions from two source mechanisms: A distributed distortion source encompassing both the DP and f2 characteristic places, and a reflection source at the DP characteristic place.

  7. Harmonic and interharmonic distortion modeling in multiconverter systems

    SciTech Connect

    Carbone, R.; Morrison, R.E.; Testa, A.; Menniti, D.

    1995-07-01

    The problem of modeling multiconverter systems in presence of harmonic and interharmonic distortion is considered. Specifically, current source rectifiers are considered as distortion sources some supply d.c. motors and the remaining supplying inverters feeding a.c. machines. The classical analogue, frequency domain and time domain models proposed in the literature to study harmonic distortion in a multiconverter system are considered and for each model suitable extension to include the interharmonic distortion are presented and critically analyzed. The results of several experiments are reported to show the usefulness and to compare the accuracy of the different extensions considered.

  8. Extraction of electron plasma energy distribution function using distortion meters

    NASA Astrophysics Data System (ADS)

    Azooz, A. A.

    2006-06-01

    A new method for direct evaluation of the electron energy distribution function in plasmas is suggested, which involves the use of audio frequencies distortion factor meters. The amount of distortion suffered by a Langmuir probe AC current produced by superimposing a clean AC voltage on the DC probe voltage is measured. Although such distortions are proportional to the second derivative of the probe characteristic at any point when its neighborhood can be approximated by a second-degree polynomial, the instrument function is always sharper than that of harmonic differentiation. The method is analyzed theoretically, and tested experimentally. It is also shown that distortion additionally provides a direct measure of the electron temperature.

  9. Distortion generated in angle-modulation systems by phased arrays

    NASA Technical Reports Server (NTRS)

    Rogers, J. D.; Lagrone, A. H.; Fowler, J.

    1973-01-01

    The magnitude and characteristics of distortion produced in demodulated signals by corporate-fed phased arrays are reviewed. Graphs depicting distortion, plotted as a function of signal characteristics and array geometry, display the effects of large arrays on broadband signals. These curves show that distortion in angle-modulation systems is more a function of modulation index than of bandwidth. The data presented provide a basis for predicting distortion levels in practical array systems and for extending analyses to other signal-array configurations.

  10. Systems and methods for mirror mounting with minimized distortion

    NASA Technical Reports Server (NTRS)

    Antonille, Scott R. (Inventor); Wallace, Thomas E. (Inventor); Content, David A. (Inventor); Wake, Shane W. (Inventor)

    2012-01-01

    A method for mounting a mirror for use in a telescope includes attaching the mirror to a plurality of adjustable mounts; determining a distortion in the mirror caused by the plurality adjustable mounts, and, if the distortion is determined to be above a predetermined level: adjusting one or more of the adjustable mounts; and determining the distortion in the mirror caused by the adjustable mounts; and in the event the determined distortion is determined to be at or below the predetermined level, rigidizing the adjustable mounts.

  11. Effects of skin elasticity on bite mark distortion.

    PubMed

    Lewis, Cheri; Marroquin, Leonor A

    2015-12-01

    Bite marks have been reported to have an evidentiary value similar to fingerprints. We believed bite mark distortion would impact the accuracy and reliability of bite mark interpretation. Inked denture-stamps were substituted for actual bite marks and were placed onto 40 participating volunteers' shoulders. Four changes in arm position were photographed using an ABFO #2 reference scale. The measurements of individual tooth widths and intercanine distances in each position were compared. The maximum tooth width distortion observed was 53.8%, whereas the maximum intercanine distance distortion was 41.9%. Distortion was found to increase with age and weight and was non-uniform across a dental arch. PMID:26451773

  12. Effect of liquid distortion and aperture shape on the quality of bubble chamber photographs.

    PubMed

    Price, M J; Vinter, B

    1973-11-01

    When a plane wave that has passed through a turbulent liquid is brought to a focus by a lens, the image moves erratically. The distortion produced by the liquid is here defined as the root-mean-square distance of the centroid of the diffraction pattern from its mean position. Expressions have been obtained that enable one to calculate this quantity as a function of liquid conditions and the results have been used to judge the effectiveness of using annular apertures in the photography of propane bubble chamber events.

  13. Distortion product otoacoustic emissions in geriatric dogs.

    PubMed

    Strain, G M; Rosado Martinez, A J; McGee, K A; McMillan, C L

    2016-10-01

    Recordings of distortion product otoacoustic emissions (DPOAE) were taken from 28 geriatric dogs aged 12.2 ± 2.2 years and 15 control dogs aged 5.9 ± 3.0 years (mean ± standard deviation) to demonstrate frequency-specific changes in cochlear responses. Recordings were performed for primary frequencies of 2-12 kHz in 2 kHz increments. Brainstem auditory evoked response (BAER) recordings were also made from geriatric dogs for comparison with DPOAE responses. Significant decreases in DPOAE response amplitudes were observed at frequencies of 6-12 kHz in geriatric dogs compared to control dogs, reflecting loss of cochlear outer hair cells along the length of the cochlea. Significant decreases in response amplitudes were not seen at frequencies of 2 or 4 kHz. Decreases in BAER response amplitudes subjectively paralleled the depressed DPOAE amplitudes. No significant linear regression relationships were found for DPOAE response amplitude vs. age despite the progressive nature of age-related hearing loss. The reductions in response at all frequencies starting at the age where dogs are considered geriatric indicate that age-related hearing loss begins earlier in the life span. DPOAE recordings provide a means to assess cochlear function across different portions of the auditory spectrum for assessing hearing loss associated with aging, and potentially for losses from other causes of decreased auditory function.

  14. Local Distortions in PbTe:Tl

    NASA Astrophysics Data System (ADS)

    Keiber, Trevor; Bridges, Frank; Sales, Brian

    2013-03-01

    Lead Telluride (PbTe) is a well characterized thermoelectric material. Tl doping increases the figure of merit with a maximum at 2% Tl. Recent X-ray diffraction and total neutron scattering experiments suggest Pb moves off-center along the 100 axis as T increases. To investigate the local structure we present an Extended X-ray Absorption Fine Structure (EXAFS) analysis for 0-3% Tl concentrations at the Tl and Pb L3 edges and at the Te K edge. At 10K the local structure about Pb is well ordered, the Pb-Te (Te-Pb) pair distribution function (PDF) broadens rapidly with T. Attempts to model the increase in σ2(T) for the Pb-Te pair (σ is the width of the PDF) with a 100 Pb off-center displacement, were not successful. However σ2(T) for the Pb-Te pair is well described by a correlated Debye model with a low correlated Debye temperature. The Te edge shows increased disorder for the the Te-Te pair and later peaks which may be caused by a structural change around the Te atom. For Tl, the environment is distorted even at 10K within the host material. This indicates a large variation of the Tl-Te bond lengths, presumably as a result of the presence of Tl(+1). We discuss possible models for the disorder about Tl, Pb, and Te in PbTe:Tl. Support: NSF DMR 1005568

  15. Distortion product otoacoustic emissions in geriatric dogs.

    PubMed

    Strain, G M; Rosado Martinez, A J; McGee, K A; McMillan, C L

    2016-10-01

    Recordings of distortion product otoacoustic emissions (DPOAE) were taken from 28 geriatric dogs aged 12.2 ± 2.2 years and 15 control dogs aged 5.9 ± 3.0 years (mean ± standard deviation) to demonstrate frequency-specific changes in cochlear responses. Recordings were performed for primary frequencies of 2-12 kHz in 2 kHz increments. Brainstem auditory evoked response (BAER) recordings were also made from geriatric dogs for comparison with DPOAE responses. Significant decreases in DPOAE response amplitudes were observed at frequencies of 6-12 kHz in geriatric dogs compared to control dogs, reflecting loss of cochlear outer hair cells along the length of the cochlea. Significant decreases in response amplitudes were not seen at frequencies of 2 or 4 kHz. Decreases in BAER response amplitudes subjectively paralleled the depressed DPOAE amplitudes. No significant linear regression relationships were found for DPOAE response amplitude vs. age despite the progressive nature of age-related hearing loss. The reductions in response at all frequencies starting at the age where dogs are considered geriatric indicate that age-related hearing loss begins earlier in the life span. DPOAE recordings provide a means to assess cochlear function across different portions of the auditory spectrum for assessing hearing loss associated with aging, and potentially for losses from other causes of decreased auditory function. PMID:27687934

  16. Understanding Pretrial Publicity: Predecisional Distortion of Evidence by Mock Jurors

    ERIC Educational Resources Information Center

    Hope, Lorraine; Memon, Amina; McGeorge, Peter

    2004-01-01

    Prejudicial pretrial publicity (PTP) constitutes a serious source of juror bias. The current study examined differences in predecisional distortion for mock jurors exposed to negative PTP (N-PTP) versus nonexposed control participants. According to work by K. A. Carlson and J. E. Russo (2001), predecisional distortion occurs when jurors bias new…

  17. Audiovisual Cues and Perceptual Learning of Spectrally Distorted Speech

    ERIC Educational Resources Information Center

    Pilling, Michael; Thomas, Sharon

    2011-01-01

    Two experiments investigate the effectiveness of audiovisual (AV) speech cues (cues derived from both seeing and hearing a talker speak) in facilitating perceptual learning of spectrally distorted speech. Speech was distorted through an eight channel noise-vocoder which shifted the spectral envelope of the speech signal to simulate the properties…

  18. The Saturation Campaign of Lies and Distortions about Educational Vouchers.

    ERIC Educational Resources Information Center

    Fuller, Howard L.

    This paper asserts that a campaign of "distortions and lies" about educational vouchers is being conducted by opponents of expanded educational options for low-income parents. It suggests that aspects of the voucher debate are subject to frequent distortion, refuting myths that are being spread. These focus on such issues as: overall admission…

  19. The ISOCAM field-of-view distortion correction

    NASA Technical Reports Server (NTRS)

    Ali, B.; Ott, S.; Vo, T. D.; Gastaud, R.; Okumura, K.

    2000-01-01

    We describe results from new re-analysis of the ISOCAM field-of-view distortion. In this contribution we describe the procedure for determining the distortion, the implentation and resulting effects on the ISOCAM astrometric measurements, mosaicking and flux calibration.

  20. Distortion of Probability and Outcome Information in Risky Decisions

    ERIC Educational Resources Information Center

    DeKay, Michael L.; Patino-Echeverri, Dalia; Fischbeck, Paul S.

    2009-01-01

    Substantial evidence indicates that information is distorted during decision making, but very few studies have assessed the distortion of probability and outcome information in risky decisions. In two studies involving six binary decisions (e.g., banning blood donations from people who have visited England, because of "mad cow disease"), student…

  1. Quadratic elongation: A quantitative measure of distortion in coordination polyhedra

    USGS Publications Warehouse

    Robinson, Kelly F.; Gibbs, G.V.; Ribbe, P.H.

    1971-01-01

    Quadratic elongation and the variance of bond angles are linearly correlated for distorted octahedral and tetrahedral coordination complexes, both of which show variations in bond length and bond angle. The quadratic elonga tion is dimensionless, giving a quantitative measure of polyhedral distortion which is independent of the effective size of the polyhedron.

  2. Compact fluorescent lamps, LED lamps and harmonic distortion

    NASA Astrophysics Data System (ADS)

    Franco, A. M. R.; Debatin, R. M.; Cotia, F. C. G.; Silva, M. V. M.; Ribeiro, R. S.; Zampilis, R. R. N.

    2015-01-01

    The aim of this paper is to evaluate the harmonic distortion in the current waveform of Compact Fluorescent Lamps (CFL) and Lamps Lighting Emitting Diode (LED). For this, we analysed the power factor, voltage waveform, current waveform, total harmonic distortion (THD) and active power consumed.

  3. Cognitive Distortion in Rheumatoid Arthritis: Relation to Depression and Disability.

    ERIC Educational Resources Information Center

    Smith, Timothy W.; And Others

    1988-01-01

    Examined the relation between cognitive distortion, as measured by the Cognitive Error Questionnaire, and both self-reported and interview-rated depression and disability in 92 rheumatoid arthritis (RA) patients. Found cognitive distortion significantly associated with depression, and also related to physical disability. Discusses the results,…

  4. Cognitive Distortion and Psychological Distress in Chronic Low Back Pain.

    ERIC Educational Resources Information Center

    Smith, Timothy W.; And Others

    1986-01-01

    Indicated that cognitive distortion was associated with high scores on the Minnesota Multiophasic Personality Inventory (MMPH) Depression (D), Psychasthenia (Pt), and Schizophrenia (Sc) scales, but not the Hypochondriasis (Hs) and Hysteria (Hy) scales. Cognitive distortion is likely to be an important factor in general distress but not in…

  5. Socioeconomic Inequality and Giftedness: Suppression and Distortion of High Ability

    ERIC Educational Resources Information Center

    Ambrose, Don

    2013-01-01

    Severe socioeconomic inequality strongly suppresses and distorts the discovery of aspirations and the concomitant development of talents among the gifted. More comprehensive understanding of this suppression and distortion is available through a wide-ranging interdisciplinary search for research findings and theories that illuminate economic,…

  6. Mass spectral peak distortion due to Fourier transform signal processing.

    PubMed

    Rockwood, Alan L; Erve, John C L

    2014-12-01

    Distortions of peaks can occur when one uses the standard method of signal processing of data from the Orbitrap and other FT-based methods of mass spectrometry. These distortions arise because the standard method of signal processing is not a linear process. If one adds two or more functions, such as time-dependent signals from a Fourier transform mass spectrometer and performs a linear operation on the sum, the result is the same as if the operation was performed on separate functions and the results added. If this relationship is not valid, the operation is non-linear and can produce unexpected and/or distorted results. Although the Fourier transform itself is a linear operator, the standard algorithm for processing spectra in Fourier transform-based methods include non-linear mathematical operators such that spectra processed by the standard algorithm may become distorted. The most serious consequence is that apparent abundances of the peaks in the spectrum may be incorrect. In light of these considerations, we performed theoretical modeling studies to illustrate several distortion effects that can be observed, including abundance distortions. In addition, we discuss experimental systems where these effects may manifest, including suggested systems for study that should demonstrate these peak distortions. Finally, we point to several examples in the literature where peak distortions may be rationalized by the phenomena presented here.

  7. Predictors of Child Molestation: Adult Attachment, Cognitive Distortions, and Empathy

    ERIC Educational Resources Information Center

    Wood, Eric; Riggs, Shelley

    2008-01-01

    A conceptual model derived from attachment theory was tested by examining adult attachment style, cognitive distortions, and both general and victim empathy in a sample of 61 paroled child molesters and 51 community controls. Results of logistic multiple regression showed that attachment anxiety, cognitive distortions, high general empathy but low…

  8. Cognitive Distortions, Coping Behavior, and Depression in College Students.

    ERIC Educational Resources Information Center

    Warren, Nancy J.; And Others

    1982-01-01

    This study explored the relationship of cognitive distortions and coping strategies to depression in college students. A measure of cognitive distortions (the Interpretation Inventory) and a measure of strategies for coping with depression (the Active Checklist) were developed and used for this study. Results are discussed. (CJ)

  9. The Relationship between Depression, Irrational Beliefs, and Cognitive Distortions.

    ERIC Educational Resources Information Center

    Chan, Florentius

    Studies have shown that depressed people have a significantly higher number of irrational beliefs and cognitive distortions than nondepressed people. The purpose of this study was to identify the causal relationship among depression, irrational beliefs, and cognitive distortions through the use of cross-lagged panel correlational analysis. On two…

  10. Mechanosensitive physiology of chlamydomonas reinhardtii under direct membrane distortion

    PubMed Central

    Min, Seul Ki; Yoon, Gwang Heum; Joo, Jung Hyun; Sim, Sang Jun; Shin, Hwa Sung

    2014-01-01

    Cellular membrane distortion invokes variations in cellular physiology. However, lack of an appropriate system to control the stress and facilitate molecular analyses has hampered progress of relevant studies. In this study, a microfluidic system that finely manipulates membrane distortion of Chlamydomonas reinhardtii (C. reinhardtii) was developed. The device facilitated a first-time demonstration that directs membrane distortion invokes variations in deflagellation, cell cycle, and lipid metabolism. C. reinhardtii showed a prolonged G1 phase with an extended total cell cycle time, and upregulated Mat3 regulated a cell size and cell cycle. Additionally, increased TAG compensated for the loss of cell mass. Overall, this study suggest that cell biology that requires direct membrane distortion can be realized using this system, and the implication of cell cycle with Mat3 expression of C. reinhardtii was first demonstrated. Finally, membrane distortion can be an attractive inducer for biodiesel production since it is reliable and robust. PMID:24728350

  11. The evolved basis and adaptive functions of cognitive distortions.

    PubMed

    Gilbert, P

    1998-12-01

    This paper explores common cognitive distortions from the perspective of evolutionary psychology. It is suggested that cognitive distortions are natural consequences of using fast track defensive algorithms that are sensitive to threat. In various contexts, especially those of threat, humans evolved to think adaptively rather than logically. Hence cognitive distortions are not strictly errors in brain functioning and it can be useful to inform patients that 'negative thinking' may be dysfunctional but is a reflection of basic brain design and not personal irrationality. The evolved nature of cognitive distortions has been implicit in cognitive therapy from its early days (Beck, 1963; Ellis, 1962) but has not been fully articulated in what is now known about evolved mental processes. Many forms of cognitive distortion can be seen to use the (previously) adaptive heuristic of better safe than sorry.

  12. Cognitive distortions in obese patients with or without eating disorders.

    PubMed

    Volery, M; Carrard, I; Rouget, P; Archinard, M; Golay, A

    2006-12-01

    In the normal weight population, cognitive distortions are more often found in people with eating disorders such as anorexia and bulimia than in a control population. With these cognitive distortions, weight and body image become central elements in self-esteem. This exploratory study investigated cognitive distortions in obese patients suffering from binge eating disorder or not. The hypothesis was that the patients suffering from binge eating disorder would have more cognitive distortions. Twenty-nine obese women (11 without and 18 with binge eating disorder) and 13 non-obese female controls were selected. To evaluate the cognitive distortions, subjects completed the Mizes Anorectic Cognitions-Revised (MAC-R) questionnaire. Contrary to our hypothesis, we found no difference in evidence between the two obese groups with or without eating disorders. Possible perspectives for treatment are discussed.

  13. Distortion effects in a switch array UWB radar for time-lapse imaging of human heartbeats

    NASA Astrophysics Data System (ADS)

    Brovoll, Sverre; Berger, Tor; Aardal, Åyvind; Lande, Tor S.; Hamran, Svein-Erik

    2014-05-01

    Cardiovascular diseases (CVD) are a major cause of deaths all over the world. Microwave radar can be an alternative sensor for heart diagnostics and monitoring in modern healthcare that aids early detection of CVD symptoms. In this paper measurements from a switch array radar system are presented. This UWB system operates below 3 GHz and does time-lapse imaging of the beating heart inside the human body. The array consists of eight fat dipole elements. With a switch system, every possible sequence of transmit/receive element pairs can be selected to build a radar image from the recordings. To make the radar waves penetrate the human tissue, the antenna array is placed in contact with the body. Removal of the direct signal leakage through the antennas and body surface are done by high-pass (HP) filtering of the data prior to image processing. To analyze the results, measurements of moving spheres in air and simulations are carried out. We see that removal of the direct signal introduces amplitude distortion in the images. In addition, the effect of small target motion between the collection times of data from the individual elements is analyzed. With low pulse repetition frequency (PRF) this motion will distort the image. By using data from real measurements of heart motion in simulations, we analyze how the PRF and the antenna geometry influence this distortions.

  14. Microelectrical Mechanical Systems Flow Control Used to Manage Engine Face Distortion in Compact Inlet Systems

    NASA Technical Reports Server (NTRS)

    Anderson, Bernhard H.; Miller, Daniel N.

    1999-01-01

    Turbofan engine-face flow distortion is one of the most troublesome and least understood problems for designers of modern engine inlet systems. One concern is that there are numerous sources of flow-field distortion that are ingested by the inlet or generated within the inlet duct itself. Among these are: (1) flow separation at the cowl lip during in-flight maneuvering, (2) flow separation on the compression surfaces due to shock-wave/boundary layer interactions, (3) spillage of the fuselage boundary layer into the inlet duct, (4) ingestion of aircraft vortices and wakes emanating from upstream disturbances, and (5) strong secondary flow gradients and flow separation induced by wall curvature within the inlet duct itself. Most developing aircraft (including the B70, F-111, F-14, Mig-25, Tornado, and Airbus A300) have experienced one or more of these types of problems, particularly at high Mach numbers and/or extreme maneuver conditions when flow distortion at the engine face exceeded the allowable limits of the engine.

  15. Influence of surface active solute on ultrasonic waveform distortion in liquid containing air bubbles.

    PubMed

    Tuziuti, Toru; Yasui, Kyuichi; Lee, Judy; Kozuka, Teruyuki; Towata, Atsuya; Iida, Yasuo

    2009-08-01

    The influence of sodium dodecyl sulfate (SDS) on waveform distortion of 141 kHz ultrasonic standing waves in liquids containing air bubbles was investigated for various transducer powers. Fast Fourier transform (FFT) operations were performed on the pressure waveform to obtain the harmonic components. In addition, the intensity of sonoluminescence (SL) was measured as a function of the power. Waveform distortion was observed for water at high applied power, with the curve exhibiting a steeper gradient for positive pressures and a broadened minimum for negative pressures. This was in reasonable agreement with theoretical studies reported in the literature. Much less distortion was found for a 1 mM SDS solution as the applied power was increased than for water or a 10 mM SDS solution. This may be attributed to a lower population of large coalesced bubbles in the 1 mM solution due to electrostatic repulsion, leading to damping of the sound energy and little cavitation noise because of viscous resistance to bubble radial motion in addition to adsorption and desorption of surfactant molecules at the bubble-liquid interface. For 10 mM SDS, the power threshold for the harmonic components was lower than that for the SL. In this case, it appears that there is a range of applied powers where most bubbles are stable and cannot collapse. The influence of the addition of an electrolyte and a nonionic surfactant was also investigated.

  16. Quantifying and Reducing Posture-Dependent Distortion in Ballistocardiogram Measurements

    PubMed Central

    Javaid, Abdul Q.; Wiens, Andrew D.; Fesmire, N. Forrest; Weitnauer, Mary A.; Inan, Omer T.

    2015-01-01

    Ballistocardiography is a non-invasive measurement of the mechanical movement of the body caused by cardiac ejection of blood. Recent studies have demonstrated that ballistocardiogram (BCG) signals can be measured using a modified home weighing scale, and used to track changes in myocardial contractility and cardiac output. With this approach, the BCG can potentially be used both for preventive screening and for chronic disease management applications. However, for achieving high signal quality, subjects are required to stand still on the scale in an upright position for the measurement; the effects of intentional (for user comfort) or unintentional (due to user error) modifications in the position or posture of the subject during the measurement have not been investigated in the existing literature. In this study, we quantified the effects of different standing and seated postures on the measured BCG signals, and on the most salient BCG-derived features compared to reference standard measurements (e.g., impedance cardiography). We determined that the standing upright posture led to the least distorted signals as hypothesized, and that the correlation between BCG-derived timing interval features (R-J interval) and the pre-ejection period, PEP (measured using ICG), decreased significantly with impaired posture or sitting position. We further implemented two novel approaches to improve the PEP estimates from other standing and sitting postures, using system identification and improved J-wave detection methods. These approaches can improve the usability of standing BCG measurements in unsupervised settings (i.e. the home), by improving the robustness to non-ideal posture, as well as enabling high quality seated BCG measurements. PMID:26058064

  17. Redshift-space distortions around voids

    NASA Astrophysics Data System (ADS)

    Cai, Yan-Chuan; Taylor, Andy; Peacock, John A.; Padilla, Nelson

    2016-11-01

    We have derived estimators for the linear growth rate of density fluctuations using the cross-correlation function (CCF) of voids and haloes in redshift space. In linear theory, this CCF contains only monopole and quadrupole terms. At scales greater than the void radius, linear theory is a good match to voids traced out by haloes; small-scale random velocities are unimportant at these radii, only tending to cause small and often negligible elongation of the CCF near its origin. By extracting the monopole and quadrupole from the CCF, we measure the linear growth rate without prior knowledge of the void profile or velocity dispersion. We recover the linear growth parameter β to 9 per cent precision from an effective volume of 3( h-1Gpc)3 using voids with radius >25 h-1Mpc. Smaller voids are predominantly sub-voids, which may be more sensitive to the random velocity dispersion; they introduce noise and do not help to improve measurements. Adding velocity dispersion as a free parameter allows us to use information at radii as small as half of the void radius. The precision on β is reduced to 5 per cent. Voids show diverse shapes in redshift space, and can appear either elongated or flattened along the line of sight. This can be explained by the competing amplitudes of the local density contrast, plus the radial velocity profile and its gradient. The distortion pattern is therefore determined solely by the void profile and is different for void-in-cloud and void-in-void. This diversity of redshift-space void morphology complicates measurements of the Alcock-Paczynski effect using voids.

  18. Multiscale quantification of tissue spiculation and distortion for detection of architectural distortion and spiculated mass in mammography

    NASA Astrophysics Data System (ADS)

    Lao, Zhiqiang; Zheng, Xin

    2011-03-01

    This paper proposes a multiscale method to quantify tissue spiculation and distortion in mammography CAD systems that aims at improving the sensitivity in detecting architectural distortion and spiculated mass. This approach addresses the difficulty of predetermining the neighborhood size for feature extraction in characterizing lesions demonstrating spiculated mass/architectural distortion that may appear in different sizes. The quantification is based on the recognition of tissue spiculation and distortion pattern using multiscale first-order phase portrait model in texture orientation field generated by Gabor filter bank. A feature map is generated based on the multiscale quantification for each mammogram and two features are then extracted from the feature map. These two features will be combined with other mass features to provide enhanced discriminate ability in detecting lesions demonstrating spiculated mass and architectural distortion. The efficiency and efficacy of the proposed method are demonstrated with results obtained by applying the method to over 500 cancer cases and over 1000 normal cases.

  19. Distortion effects on the neutron knockout from exotic nuclei in the collision with a proton target

    NASA Astrophysics Data System (ADS)

    Cravo, E.; Crespo, R.; Deltuva, A.

    2016-05-01

    Background: Reaction theory plays a major role in the interpretation of experimental data and one needs to identify and include accurately all the relevant dynamical effects in order to extract reliable structure information. The knockout of a nucleon (neutron/proton) from a high energy exotic nucleus projectile colliding with a proton target allows to get insight on the structure of its valence and inner shells. Purpose: We aim to clarify the role of the distortion on the calculated observables for nucleon knockout, in particular, the dependence of the calculated observables on the binding energy ɛb and angular momentum L of the knockout particle, and on the mass of the projectile core, Ac. We consider mainly the knockout of a neutron that may be either in the valence or in the inner shell of the projectile nucleus. Method: Exact three-body Faddeev/Alt-Grassberger-Sandhas (Faddeev/AGS) calculations are performed for the nucleon knockout from stable and exotic nuclei in the collision of 420 MeV/u projectile beams with a proton target. Results are compared with plane-wave impulse approximation (PWIA) calculations. Results: The Faddeev/AGS formalism accurately predicts: (i) a systematic nearly logarithmic dependence of the distortion parameter on the separation energy; (ii) roughly linear dependence of the ratio of the full to the PWIA cross section on the asymmetry parameter; (iii) a distinct behavior between the calculated transverse core momentum distribution from the PWIA and full Faddeev/AGS exact approach which indicates that distortion effects do not modify fully exclusive observables through a common renormalization factor. Conclusions: To extract structure information on deeper shells one needs to include distortion effects accurately. A systematic analysis enables to estimate the total cross section for knockout of a nucleon from a given shell of nuclei at/away the stability line of the nuclear landscape. The comparison with experimental results may

  20. Compensation of Hologram Distortion by Controlling Defocus Component in Reference Beam Wavefront for Angle Multiplexed Holograms

    NASA Astrophysics Data System (ADS)

    Muroi, T.; Kinoshita, N.; Ishii, N.; Kamijo, K.; Kawata, Y.; Kikuchi, H.

    2013-12-01

    Holographic memory has the potential to function as a recording system with a large capacity and high data-transfer-rate. Photopolymer materials are typically used as a write-once recording medium. When holograms are recorded on this medium, they can distort due to shrinkage or expansion of the materials, which degrades the reconstructed image and causes a higher bit error rate (bER) of the reproduced data. We propose optically compensating for hologram distortion by controlling aberration components in the reference beam wavefront while reproducing data, thereby improving the reproduced data quality. First, we investigated the relation between each aberration component of the reference beam and the signal to noise ratio (SNR) of the reproduced data using numerical simulation and found that horizontal tilt and the defocus component affect the SNR. Next, we experimentally evaluated the reproduced data by controlling the defocus component in the reference beam and found that the bER of the reproduced data could be decreased by controlling the defocus center with respect to the hologram position and phase modulation depth of the defocus component. Then, we investigated a practical control method of the defocus component using an evaluation value similar to the definition of the SNR for actual data reproduction from holograms. Using a defocus controlled wavefront enabled us to decrease the bER from 3.54 x 10^-3 with a plane wave to 3.14 x 10^-4. We also investigated how to reduce the bERs of reproduced data in angle multiplexed holograms. By using a defocus controlled wavefront to compensate for hologram distortion on the 40th data page in 80-page angle multiplexed holograms, the bERs of all pages could be decreased to less than 1x10^-3. We showed that controlling the defocus component is an effective way to compensate for hologram distortion and to decrease the bER of reproduced data in holographic memory.

  1. A survey of inlet/engine distortion compatibility

    NASA Technical Reports Server (NTRS)

    Bowditch, D. N.; Coltrin, R. E.

    1983-01-01

    The history of distortion analysis is traced back to its origin in parallel compressor theory which was initially proposed in the late fifties. The development of this theory is reviewed up to its inclusion in the complex computer codes of today. It is found to be a very useful tool to guide development but not quantitative enough to predict compatibility. Dynamic or instantaneous distortion methodology is also reviewed from its origins in the sixties, to its current application in the eighties. Many of the requirements for interpreting instantaneous distortion are considered and illustrated. Statistical methods for predicting the peak distortion are described, and their limitations and advantages discussed. Finally, some Reynolds number and scaling considerations for inlet testing are considered. It is concluded that the deterministic instantaneous distortion methodology combined with distortion testing of engines with screens will remain the primary method of predicting compatibility for the near future. However, parallel compressor analysis and statistical peak distortion prediction will be important tools employed during the development of inlet/engine compatibility.

  2. High-precision camera distortion measurements with a ``calibration harp''

    NASA Astrophysics Data System (ADS)

    Tang, Zhongwei; Grompone von Gioi, Rafael; Monasse, Pascal; Morel, Jean-Michel

    2012-10-01

    This paper addresses the high precision measurement of the distortion of a digital camera from photographs. Traditionally, this distortion is measured from photographs of a flat pattern which contains aligned elements. Nevertheless, it is nearly impossible to fabricate a very flat pattern and to validate its flatness. This fact limits the attainable measurable precisions. In contrast, it is much easier to obtain physically very precise straight lines by tightly stretching good quality strings on a frame. Taking literally "plumb-line methods", we built a "calibration harp" instead of the classic flat patterns to obtain a high precision measurement tool, demonstrably reaching 2/100 pixel precisions. The harp is complemented with the algorithms computing automatically from harp photographs two different and complementary lens distortion measurements. The precision of the method is evaluated on images corrected by state-of-the-art distortion correction algorithms, and by popular software. Three applications are shown: first an objective and reliable measurement of the result of any distortion correction. Second, the harp permits to control state-of-the art global camera calibration algorithms: It permits to select the right distortion model, thus avoiding internal compensation errors inherent to these methods. Third, the method replaces manual procedures in other distortion correction methods, makes them fully automatic, and increases their reliability and precision.

  3. Bilateral Symmetry of Distortions of Tactile Size Perception.

    PubMed

    Longo, Matthew R; Ghosh, Arko; Yahya, Tasneem

    2015-01-01

    The perceived distance between touches on the limbs is generally bigger for distances oriented across the width of the limb than for distances oriented along the length of the limb. The present study aimed to investigate the coherence of such distortions of tactile size perception across different skin surfaces. We investigated distortions of tactile size perception on the dorsal and palmar surfaces of both the left and right hands as well as the forehead. Participants judged which of two tactile distances felt larger. One distance was aligned with the proximodistal axis (along the body), the other with the mediolateral axis (across the body). Clear distortions were found on all five skin surfaces, with stimuli oriented across the width of the body being perceived as farther apart than those oriented along the length of the body. Consistent with previous results, distortions were smaller on the palmar than on the dorsal hand surface. Distortion on the forehead was intermediate between the dorsal and palmar surfaces. There were clear correlations between distortion on the left and right hands, for both the dorsal and palmar skin surfaces. In contrast, within each hand, there was no significant correlation between the two skin surfaces. Distortion on the forehead was not significantly correlated with that on any of the other skin surfaces. These results provide evidence for bilaterally symmetric representations underlying tactile size perception.

  4. Simultaneous Electromagnetic Tracking and Calibration for Dynamic Field Distortion Compensation.

    PubMed

    Sadjadi, Hossein; Hashtrudi-Zaad, Keyvan; Fichtinger, Gabor

    2016-08-01

    Electromagnetic (EM) tracking systems are highly susceptible to field distortion. The interference can cause measurement errors up to a few centimeters in clinical environments, which limits the reliability of these systems. Unless corrected for, this measurement error imperils the success of clinical procedures. It is therefore fundamental to dynamically calibrate EM tracking systems and compensate for measurement error caused by field distorting objects commonly present in clinical environments. We propose to combine a motion model with observations of redundant EM sensors and compensate for field distortions in real time. We employ a simultaneous localization and mapping technique to accurately estimate the pose of the tracked instrument while creating the field distortion map. We conducted experiments with six degrees-of-freedom motions in the presence of field distorting objects in research and clinical environments. We applied our approach to improve the EM tracking accuracy and compared our results to a conventional sensor fusion technique. Using our approach, the maximum tracking error was reduced by 67% for position measurements and by 64% for orientation measurements. Currently, clinical applications of EM trackers are hampered by the adverse distortion effects. Our approach introduces a novel method for dynamic field distortion compensation, independent from preoperative calibrations or external tracking devices, and enables reliable EM navigation for potential applications. PMID:26595908

  5. Which spectral distortions does ΛCDM actually predict?

    NASA Astrophysics Data System (ADS)

    Chluba, Jens

    2016-07-01

    Ever refined cosmological measurements have established the ΛCDM concordance model, with the key cosmological parameters being determined to per cent-level precision today. This allows us to make explicit predictions for the spectral distortions of the cosmic microwave background (CMB) created by various processes occurring in the early Universe. Here, we summarize all guaranteed CMB distortions and assess their total uncertainty within ΛCDM. We also compare simple methods for approximating them, highlighting some of the subtle aspects when it comes to interpreting future distortion measurements. Under simplified assumptions, we briefly study how well a PIXIE-like experiment may measure the main distortion parameters (i.e. μ and y). Next-generation CMB spectrometers are expected to detect the distortion caused by reionization and structure formation at extremely high significance. They will also be able to constrain the small-scale power spectrum through the associated μ-distortion, improving limits on running of the spectral index. Distortions from the recombination era, adiabatic cooling of matter relative to the CMB and dark matter annihilation require a higher sensitivity than PIXIE in its current design. The crucial next step is an improved modelling of foregrounds and instrumental aspects, as we briefly discuss here.

  6. Laser beacon wave-front sensing without focal anisoplanatism.

    PubMed

    Buscher, D F; Love, G D; Myers, R M

    2002-02-01

    Wave-front sensing from artificial beacons is normally performed by formation of a focused spot in the atmosphere and sensing of the wave-front distortions produced during the beam's return passage. We propose an alternative method that senses the distortions produced during the outgoing path by forming an intensity pattern in the atmosphere that is then viewed from the ground. A key advantage of this method is that a parallel beam is used, and therefore the wave-front measurements will not suffer from the effects of focal anisoplanatism. We also envisage other geometries, all based on the concept of projecting a pupil pattern onto the atmosphere.

  7. Signal distortion on VHF/UHF transionospheric paths: First results from the Wideband Ionospheric Distortion Experiment

    NASA Astrophysics Data System (ADS)

    Cannon, Paul S.; Groves, Keith; Fraser, David J.; Donnelly, William J.; Perrier, Kathleen

    2006-10-01

    To the best of our knowledge, we report the first determination of ionospheric distortion, comprising the simultaneous characterization of both multipath and Doppler, on wideband, transionospheric VHF (158 MHz) and UHF (422 MHz) signals. The measurements took place as part of the test phase of the United Kingdom-United States Wideband Ionospheric Distortion Experiment during the evening (˜1000 UT) of 18 January 2005. This characterization has been achieved using the ALTAIR radar at the Ronald Reagan Ballistic Missile Defense Test Site on Kwajalein Atoll (9.395°N, 167.469°E (12.87°N, 237.16°E corrected geomagnetic)) in the Pacific, in conjunction with a low Earth orbiting, constant radar cross-section, passive satellite (calibration sphere). During the period when the two-way S4 index was above ˜0.8 on both channels, the median coherency times were 43 and 96 ms at VHF and UHF, respectively (at 1.5σ). The corresponding median coherency bandwidths were 0.8 and 2.1 MHz.

  8. Opdic (optimized Peak, Distortion and Clutter) Detection Filter.

    NASA Astrophysics Data System (ADS)

    House, Gregory Philip

    1995-01-01

    Detection is considered. This involves determining regions of interest (ROIs) in a scene: the locations of multiple object classes in a scene in clutter when object distortions and contrast differences are present. High probability of detection P_{D} is essential and low P_{FA } is desirable since subsequent stages in the full system will only decrease P_{FA } and cannot increase P_{D }. Low resolution blob objects and objects with more internal detail are considered with both 3-D aspect view and depression angle distortions present. Extensive tests were conducted on 56 scenes with object classes not present in the training set. A modified MINACE (Minimum Noise and Correlation Energy) distortion-invariant filter was used. This minimizes correlation plane energy due to distortions and clutter while satisfying correlation peak constraint values for various object-aspect views. The filter was modified with a new object model (to give predictable output peak values) and a new correlated noise clutter model; a white Gaussian noise model of distortion was used; and a new techniques to increase the number of training set images (N _{T}) included in the filter were developed. Excellent results were obtained. However, the correlation plane distortion and clutter energy functions were found to become worse as N_{T } was increased and no rigorous method exists to select the best N_{T} (when to stop filter synthesis). A new OPDIC (Optimized Peak, Distortion, and Clutter) filter was thus devised. This filter retained the new object, clutter and distortion models noted. It minimizes the variance of the correlation peak values for all training set images (not just the N_{T} images). As N _{T} increases, the peak variance and the objective functions (correlation plane distortion and clutter energy) are all minimized. Thus, this new filter optimizes the desired functions and provides an easy way to stop filter synthesis (when the objective function is minimized). Tests show

  9. Correction of perceived first-order distortions in holography.

    NASA Technical Reports Server (NTRS)

    Winter, D. C.

    1972-01-01

    Consideration of the problem of distortion posed by a long-wavelength hologram as a three-dimensional display to be viewed by an observer who is included in the distortion problem. The effects of holographic distortion upon the observer's image perception are examined. The inclusion of the visual perception process into the description of holographic imagery necessarily complicates the analysis, but at the same time increases the degrees of freedom by which the image can be altered. It is shown that these additional degrees of freedom make it possible to overcome the problem of unequal longitudinal and lateral magnification.

  10. Asymmetrical passive intermodulation distortions of memristors with mathematical behavior models

    NASA Astrophysics Data System (ADS)

    Wu, Yongle; Jin, Qiuyan; Wang, Weimin; Liu, Yuanan

    2016-10-01

    A rigorous mathematical explanation and accurate numerical prediction for asymmetrical passive intermodulation (PIM) distortions of memristors are investigated in this article. This theoretical explanation is based on behavior models of memristors representing the interrelation between terminated voltages and currents. The simulated single-tone and two-tone signal spectrums for extremely low-frequency (Hz) and microwave (GHz) applications verify our proposed mathematical approach and the new discovery of asymmetrical PIM distortions. This presented method provides an innovative choice to model and simulate the external performance of circuits and systems with asymmetrical PIM distortions in the future.

  11. Distortion of the cosmic background radiation by superconducting strings

    NASA Technical Reports Server (NTRS)

    Ostriker, J. P.; Thompson, C.

    1987-01-01

    Superconducting cosmic strings can be significant energy sources, keeping the universe ionized past the commonly assumed epoch of recombination. As a result, the spectrum of the cosmic background radiation is distorted in the presence of heated primordial gas via the Suniaev-Zel'dovich effect. Thiis distortion can be relatively large: the Compton y parameter attains a maximum in the range 0.001-0.005, with these values depending on the mass scale of the string. A significant contribution to y comes from loops decaying at high redshift when the universe is optically thick to Thomson scattering. Moreover, the isotropic spectral distortion is large compared to fluctuations at all angular scales.

  12. Recovery of pyroshock data from distorted acceleration records

    NASA Technical Reports Server (NTRS)

    Smith, J. L.

    1985-01-01

    In the past, distorted pyrotechnic shock time history data was discarded completely or cleaned up by questionable means. Too often the clean up procedures introduced as much error into the data as previously existed. Techniques are presented for data recovery so that true signals are obtained and so that these recovery procedures will be completely reproducible by any scientists in any lab. Most ordnance shock data is distorted by baseline shifts or accelerometer resonances. The methodology of recovering true signals from these two types of distortion is discussed.

  13. Distribution function approach to redshift space distortions

    SciTech Connect

    Seljak, Uroš; McDonald, Patrick E-mail: pvmcdonald@lbl.gov

    2011-11-01

    We develop a phase space distribution function approach to redshift space distortions (RSD), in which the redshift space density can be written as a sum over velocity moments of the distribution function. These moments are density weighted and have well defined physical interpretation: their lowest orders are density, momentum density, and stress energy density. The series expansion is convergent if kμu/aH < 1, where k is the wavevector, H the Hubble parameter, u the typical gravitational velocity and μ = cos θ, with θ being the angle between the Fourier mode and the line of sight. We perform an expansion of these velocity moments into helicity modes, which are eigenmodes under rotation around the axis of Fourier mode direction, generalizing the scalar, vector, tensor decomposition of perturbations to an arbitrary order. We show that only equal helicity moments correlate and derive the angular dependence of the individual contributions to the redshift space power spectrum. We show that the dominant term of μ{sup 2} dependence on large scales is the cross-correlation between the density and scalar part of momentum density, which can be related to the time derivative of the matter power spectrum. Additional terms contributing to μ{sup 2} and dominating on small scales are the vector part of momentum density-momentum density correlations, the energy density-density correlations, and the scalar part of anisotropic stress density-density correlations. The second term is what is usually associated with the small scale Fingers-of-God damping and always suppresses power, but the first term comes with the opposite sign and always adds power. Similarly, we identify 7 terms contributing to μ{sup 4} dependence. Some of the advantages of the distribution function approach are that the series expansion converges on large scales and remains valid in multi-stream situations. We finish with a brief discussion of implications for RSD in galaxies relative to dark matter

  14. Making Waves.

    ERIC Educational Resources Information Center

    DeClark, Tom

    2000-01-01

    Presents an activity on waves that addresses the state standards and benchmarks of Michigan. Demonstrates waves and studies wave's medium, motion, and frequency. The activity is designed to address different learning styles. (YDS)

  15. A method to correct coordinate distortion in EBSD maps

    SciTech Connect

    Zhang, Y.B. Elbrønd, A.; Lin, F.X.

    2014-10-15

    Drift during electron backscatter diffraction mapping leads to coordinate distortions in resulting orientation maps, which affects, in some cases significantly, the accuracy of analysis. A method, thin plate spline, is introduced and tested to correct such coordinate distortions in the maps after the electron backscatter diffraction measurements. The accuracy of the correction as well as theoretical and practical aspects of using the thin plate spline method is discussed in detail. By comparing with other correction methods, it is shown that the thin plate spline method is most efficient to correct different local distortions in the electron backscatter diffraction maps. - Highlights: • A new method is suggested to correct nonlinear spatial distortion in EBSD maps. • The method corrects EBSD maps more precisely than presently available methods. • Errors less than 1–2 pixels are typically obtained. • Direct quantitative analysis of dynamic data are available after this correction.

  16. Optical Distortion Evaluation in Large Area Windows using Interferometry

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.; Skow, Miles; Nurge, Mark A.

    2015-01-01

    It is important that imagery seen through large area windows, such as those used on space vehicles, not be substantially distorted. Many approaches are described in the literature for measuring the distortion of an optical window, but most suffer from either poor resolution or processing difficulties. In this paper a new definition of distortion is presented, allowing accurate measurement using an optical interferometer. This new definition is shown to be equivalent to the definitions provided by the military and the standards organizations. In order to determine the advantages and disadvantages of this new approach the distortion of an acrylic window is measured using three different methods; image comparison, Moiré interferometry, and phase-shifting interferometry.

  17. Densification and shape distortion in liquid-phase sintering

    SciTech Connect

    Liu, J.; German, R.M.

    1999-12-01

    Densification and dimensional control are important aspects of liquid-phase sintering. The capillary force and the solid bonding affect both densification and shape preservation. Capillarity, which is orientated isotropically, causes uniform shrinkage and holds grains together to preserve the component shape in the early stage of sintering. On the other hand, solid bonding resists viscous flow and inhibits densification and shape distortion. The capillary force decreases with densification and approaches zero as pores are eliminated. Thus, shape retention eventually requires solid-grain bonding. The solid-grain bonding provides compact rigidity, which is represented by compact strength. Shape distortion occurs when the compact loses its strength. For every situation, there is a critical compact strength above which no shape distortion occurs. Distortion in liquid-phase sintering indicates that the compact strength passed below a critical level.

  18. Optical phase distortion due to compressible flow over laser turrets

    NASA Technical Reports Server (NTRS)

    Fuhs, A. E.; Fuhs, S. E.

    1980-01-01

    Analytical models for optical phase distortion due to compressible flow over a laser turret are developed. Phase distortion is calculated for both blunt and small perturbation turrets. For the blunt turret, the Janzen-Rayleigh technique is used to determine the flow field. Phase distortions of 2.2 wavelengths at 3.8 microns are calculated for the blunt turret. For small perturbation turrets, a versatile analytical model is developed for a turret on a fuselage with circular cross section. With a two dimensional Fourier series representation of the turret, any shape can be considered. Both subsonic and supersonic flows can be calculated. Phase distortions of 1.2 wavelengths at 3.8 microns are calculated for one turret at high subsonic Mach number. In addition to being of value for laser turrets, the methods are applicable to reconnaissance aircraft using photographic equipment and cruise missiles using celestial navigation.

  19. Preliminary mode distortion measurements on the Jefferson Lab IRFEL

    SciTech Connect

    Stephen V. Benson; Joe Gubeli; Michelle D. Shinn

    2001-08-01

    We previously reported analytical calculations of mirror distortion in a high power FEL with a near-concentric cavity. Naive assumptions about the FEL power vs. distortion led us to believe that mirror losses were much lower than expected. Recently we have directly measured the mode size and beam quality as a function of power using a resonator with a center wavelength of 5 microns. The resonator mirrors were calcium fluoride. This material exhibits a large amount of distortion for a given power but, due to the negative slope of refractive index v temperature, adds almost no optical phase distortion on the laser output. The mode in the cavity can thus be directly calculated from the measurements at the resonator output. The presence of angular jitter produced results inconsistent with cold cavity expectations. Removing the effects of the angular jitter produces results in reasonable agreement with analytical models assuming mirror losses comparable to the original expectations.

  20. Electronic bidirectional valve circuit prevents crossover distortion and threshold effect

    NASA Technical Reports Server (NTRS)

    Kernick, A.

    1966-01-01

    Four-terminal network forms a bidirectional valve which will switch or alternate an ac signal without crossover distortion or threshold effect. In this network, an isolated control signal is sufficient for circuit turn-on.

  1. Empathy deficits and cognitive distortions in child molesters.

    PubMed

    Marshall, W L; Hamilton, K; Fernandez, Y

    2001-04-01

    An attempt was made to examine the thesis that the apparent empathy deficits in child molesters are simply another aspect of their self-serving tendency to distort information by, in this case, failing to recognize victim harm. Thirty-four child molesters were compared on a victim empathy measure and a measure of cognitive distortions, with 24 nonsex offenders and 28 nonoffending males. Child molesters displayed greater cognitive distortions than the other subjects and their greatest empathy deficits were toward their own victims. Consistent with the theory being examined it was found that the empathy scores of the child molesters toward their own victims were significantly correlated with the responses to the cognitive distortions scale. The results are discussed in terms of their implications for theory and practice.

  2. MRI geometric distortion: Impact on tangential whole-breast IMRT.

    PubMed

    Walker, Amy; Metcalfe, Peter; Liney, Gary; Batumalai, Vikneswary; Dundas, Kylie; Glide-Hurst, Carri; Delaney, Geoff P; Boxer, Miriam; Yap, Mei Ling; Dowling, Jason; Rivest-Henault, David; Pogson, Elise; Holloway, Lois

    2016-01-01

    The purpose of this study was to determine the impact of magnetic resonance imaging (MRI) geometric distortions when using MRI for target delineation and planning for whole-breast, intensity-modulated radiotherapy (IMRT). Residual system distortions and combined systematic and patient-induced distortions are considered. This retrospective study investigated 18 patients who underwent whole-breast external beam radiotherapy, where both CT and MRIs were acquired for treatment planning. Distortion phantoms were imaged on two MRI systems, dedicated to radiotherapy planning (a wide, closed-bore 3T and an open-bore 1T). Patient scans were acquired on the 3T system. To simulate MRI-based planning, distortion maps representing residual system distortions were generated via deform-able registration between phantom CT and MRIs. Patient CT images and structures were altered to match the residual system distortion measured by the phantoms on each scanner. The patient CTs were also registered to the corresponding patient MRI scans, to assess patient and residual system effects. Tangential IMRT plans were generated and optimized on each resulting CT dataset, then propagated to the original patient CT space. The resulting dose distributions were then evalu-ated with respect to the standard clinically acceptable DVH and visual assessment criteria. Maximum residual systematic distortion was measured to be 7.9 mm (95% < 4.7 mm) and 11.9 mm (95% < 4.6 mm) for the 3T and 1T scanners, respectively, which did not result in clinically unacceptable plans. Eight of the plans accounting for patient and systematic distortions were deemed clinically unacceptable when assessed on the original CT. For these plans, the mean difference in PTV V95 (vol-ume receiving 95% prescription dose) was 0.13 ± 2.51% and -0.73 ± 1.93% for right- and left-sided patients, respectively. Residual system distortions alone had minimal impact on the dosimetry for the two scanners investigated. The combina-tion of

  3. Distorted five-dimensional electrically charged black holes

    NASA Astrophysics Data System (ADS)

    Abdolrahimi, Shohreh; Shoom, Andrey A.

    2014-01-01

    In this paper, we study distorted, five-dimensional, electrically charged (nonextremal) black holes on the example of a static and "axisymmetric" black hole distorted by external, electrically neutral matter. Such a black hole is represented by the solution derived here of the Einstein-Maxwell equations which admits an R1×U(1)×U(1) isometry group. The external matter, which is "located" at the asymptotic infinity, is not included in the solution. The space-time singularities are located behind the black hole's inner (Cauchy) horizon, provided that the sources of the distortion satisfy the strong energy condition. The inner (Cauchy) horizon remains regular if the distortion fields are finite and smooth at the outer horizon. The solution has some remarkable properties. There exists a certain duality transformation between the inner and the outer horizon surfaces which links surface gravity, electrostatic potential, and space-time curvature invariants calculated at the black hole horizons. The product of the inner and outer horizon areas depends only on the black hole's electric charge, and the geometric mean of the areas is the upper (lower) limit for the inner (outer) horizon area. The electromagnetic field invariant calculated at the horizons is proportional to the squared surface gravity of the horizons. The horizon areas, electrostatic potential, and surface gravity satisfy the Smarr formula. We formulated the zeroth and the first laws of mechanics and thermodynamics of the distorted black hole and found a correspondence between the global and local forms of the first law. To illustrate the effect of distortion, we consider the dipole-monopole and quadrupole-quadrupole distortion fields. The relative change in the Kretschmann scalar due to the distortion is greater at the outer horizon than at the inner one. By calculating the maximal proper time of free fall from the outer to the inner horizons, we show that the distortion can noticeably change the black hole

  4. Characteristic microwave-background distortions from collapsing spherical domain walls

    NASA Technical Reports Server (NTRS)

    Goetz, Guenter; Notzold, Dirk

    1990-01-01

    The redshift distortion induced by collapsing spherical domain walls is calculated. The most frequent microwave background distortions are found to occur at large angles in the form of blue disks. This is the angular region currently measured by the COBE satellite. COBE could therefore detect signals predicted here for domain walls with surface energy density of the order of MeV. Such values for sigma are proposed in the late-time phase-transition scenario of Hill et al. (1989).

  5. Projection lithography with distortion compensation using reticle chuck contouring

    DOEpatents

    Tichenor, Daniel A.

    2001-01-01

    A chuck for holding a reflective reticle where the chuck has an insulator block with a non-planer surface contoured to cause distortion correction of EUV radiation is provided. Upon being placed on the chuck, a thin, pliable reflective reticle will conform to the contour of the chuck's non-planer surface. When employed in a scanning photolithography system, distortion in the scanned direction is corrected.

  6. Thermal distortion analysis of a deployable parabolic reflector

    NASA Technical Reports Server (NTRS)

    Bruck, L. R.; Honeycutt, G. H.

    1973-01-01

    A thermal distortion analysis of the ATS-6 Satellite parabolic reflector was performed using NASTRAN level 15.1. The same NASTRAN finite element method was used to conduct a one g static load analysis and a dynamic analysis of the reflector. In addition, a parametric study was made to determine which parameters had the greatest effect on the thermal distortions. The method used to model the construction of the reflector is described and the results of the analyses are presented.

  7. Correlation of lattice distortion with photocatalytic activity of titanium dioxide

    SciTech Connect

    Wang Xia; Shui Miao Li Rongsheng; Song Yue

    2008-08-04

    The photocatalytic activity of titanium dioxide dispersions on X-3B pigment degradation has been investigated. A variety of factors that would influence the photocatalytic activity such as crystallite size, lattice distortion, and anatase content are discussed in detail. It is found that lattice distortion is the most important one among these factors and is expected to inhibit the hole and electron pair recombination. It determines, to some extent, the photocatalytic efficiency of titanium dioxide dispersions.

  8. Nanostructure-Induced Distortion in Single-Emitter Microscopy.

    PubMed

    Lim, Kangmook; Ropp, Chad; Barik, Sabyasachi; Fourkas, John; Shapiro, Benjamin; Waks, Edo

    2016-09-14

    Single-emitter microscopy has emerged as a promising method of imaging nanostructures with nanoscale resolution. This technique uses the centroid position of an emitter's far-field radiation pattern to infer its position to a precision that is far below the diffraction limit. However, nanostructures composed of high-dielectric materials such as noble metals can distort the far-field radiation pattern. Previous work has shown that these distortions can significantly degrade the imaging of the local density of states in metallic nanowires using polarization-resolved imaging. But unlike nanowires, nanoparticles do not have a well-defined axis of symmetry, which makes polarization-resolved imaging difficult to apply. Nanoparticles also exhibit a more complex range of distortions, because in addition to introducing a high dielectric surface, they also act as efficient scatterers. Thus, the distortion effects of nanoparticles in single-emitter microscopy remains poorly understood. Here we demonstrate that metallic nanoparticles can significantly distort the accuracy of single-emitter imaging at distances exceeding 300 nm. We use a single quantum dot to probe both the magnitude and the direction of the metallic nanoparticle-induced imaging distortion and show that the diffraction spot of the quantum dot can shift by more than 35 nm. The centroid position of the emitter generally shifts away from the nanoparticle position, which is in contradiction to the conventional wisdom that the nanoparticle is a scattering object that will pull in the diffraction spot of the emitter toward its center. These results suggest that dielectric distortion of the emission pattern dominates over scattering. We also show that by monitoring the distortion of the quantum dot diffraction spot we can obtain high-resolution spatial images of the nanoparticle, providing a new method for performing highly precise, subdiffraction spatial imaging. These results provide a better understanding of the

  9. On the Components of Segregation Distortion in DROSOPHILA MELANOGASTER

    PubMed Central

    Ganetzky, Barry

    1977-01-01

    The segregation distorter (SD) complex is a naturally occurring meiotic drive system with the property that males heterozygous for an SD-bearing chromosome 2 and an SD+-bearing homolog transmit the SD-bearing chromosome almost exclusively. This distorted segregation is the consequence of an induced dysfunction of those sperm that receive the SD+ homolog. From previous studies, two loci have been implicated in this phenomenon: the Sd locus which is required to produce distortion, and the Responder (Rsp) locus that is the site at which Sd acts. There are two allelic alternatives of Rsp—sensitive (Rspsens) and insensitive (Rspins); a chromosome carrying Rspins is not distorted by SD. In the present study, the function and location of each of these elements was examined by a genetic and cytological characterization of X-ray-induced mutations at each locus. The results indicate the following: (1) the Rsp locus is located in the proximal heterochromatin of 2R; (2) a deletion for the Rsp locus renders a chromosome insensitive to distortion; (3) the Sd locus is located to the left of pr (2-54.5), in the region from 37D2-D7 to 38A6-B2 of the salivary chromosome map; (4) an SD chromosome deleted for Sd loses its ability to distort; (5) there is another important component of the SD system, E(SD), in or near the proximal heterochromatin of 2L, that behaves as a strong enhancer of distortion. The results of these studies allow a reinterpretation of results from earlier analyses of the SD system and serve to limit the possible mechanisms to account for segregation distortion. PMID:407128

  10. SBS (stimulated Brillouin scattering) pulse distortion in multimode optical fibers

    SciTech Connect

    Smith, J.R.; Hawkins, R.J.; Laumann, C.W.; Hatch, J. )

    1989-01-01

    We have observed sever temporal-pulse-shape distortion due to stimulated Brillouin scattering (SBS) in multimode optical fibers used to diagnose 351 m laser pulses on the Nova laser system. Our measurements can be fit by a basic model of SBS and provide a clear indication of the intensity and temporal regimes where significant SBS-induced temporal-pulse-shape distortion can be avoided. 15 refs., 3 figs., 1 tab.

  11. Predictors of child molestation: adult attachment, cognitive distortions, and empathy.

    PubMed

    Wood, Eric; Riggs, Shelley

    2008-02-01

    A conceptual model derived from attachment theory was tested by examining adult attachment style, cognitive distortions, and both general and victim empathy in a sample of 61 paroled child molesters and 51 community controls. Results of logistic multiple regression showed that attachment anxiety, cognitive distortions, high general empathy but low victim empathy significantly increased the odds of child molester status. Findings supported theoretically based hypotheses, suggesting that attachment theory may be useful in the conceptualization and treatment of child molesters.

  12. Interaction of Oblique Instability Waves with Weak Streamwise Vortices

    NASA Technical Reports Server (NTRS)

    Goldstein, M. E.; Wundrow, David W.

    1994-01-01

    This paper is concerned with the effect of a weak spanwise-variable mean-flow distortion on the growth of oblique instability waves in a Blasius boundary layer. The streamwise component of the distortion velocity initially grows linearly with increasing streamwise distance, reaches a maximum, and eventually decays through the action of viscosity. This decay occurs slowly and allows the distortion to destabilize the Blasius flow over a relatively large streamwise region. It is shown that even relatively weak distortions can cause certain oblique Rayleigh instability waves to grow much faster than the usual two-dimensional Tollmien-Schlichting waves that would be the dominant instability modes in the absence of the distortion. The oblique instability waves can then become large enough to interact nonlinearly within a common critical layer. It is shown that the resulting nonlinearity is weak and that the common amplitude of the interacting oblique waves is governed by the amplitude evolution equation derived in Goldstein & Choi (1989). The implications of these results for Klebanoff-type transition are discussed.

  13. Multimodal Sensory Distortions in Post-partum Exacerbation of Schizophrenia.

    PubMed

    Mehta, Urvakhsh Meherwan; Naveen Kumar, C; Venkatasubramanian, Ganesan; Thirthalli, Jagadisha

    2013-11-25

    Background: Sensory distortions of body image commonly occur during migraine, seizures, non-dominant cortical infarcts and hallucinogen abuse.Methods: We report the case of a 30-year-old woman with paranoid schizophrenia, presenting with post-partum onset multimodal sensory distortions in the absence of any neurological disorders or substance use.Results: Her symptoms involved persistent facial/body metamorphopsia (distorted images) and vocal paracousis (distorted voices), in the absence of visual hallucinations, illusions or agnosia. Neuropsychological assessments revealed deficits on visual processing tasks. Neuroimaging, electroencephalography and ophthalmological evaluation revealed no abnormalities. The multimodal sensory distortions responded to anti-psychotic treatment, paralleling improvement in other schizophrenia psychopathology, over a period of one month.Conclusion: Prominent and persistent multimodal sensory distortions like metamorphopsia and paracousis in the presence of psychotic symptoms warrant a detailed neurological and general medical work-up. These symptoms presenting in the absence of neurological or substance use disorders may be a component of schizophrenia. PMID:24275634

  14. Economic choices reveal probability distortion in macaque monkeys.

    PubMed

    Stauffer, William R; Lak, Armin; Bossaerts, Peter; Schultz, Wolfram

    2015-02-18

    Economic choices are largely determined by two principal elements, reward value (utility) and probability. Although nonlinear utility functions have been acknowledged for centuries, nonlinear probability weighting (probability distortion) was only recently recognized as a ubiquitous aspect of real-world choice behavior. Even when outcome probabilities are known and acknowledged, human decision makers often overweight low probability outcomes and underweight high probability outcomes. Whereas recent studies measured utility functions and their corresponding neural correlates in monkeys, it is not known whether monkeys distort probability in a manner similar to humans. Therefore, we investigated economic choices in macaque monkeys for evidence of probability distortion. We trained two monkeys to predict reward from probabilistic gambles with constant outcome values (0.5 ml or nothing). The probability of winning was conveyed using explicit visual cues (sector stimuli). Choices between the gambles revealed that the monkeys used the explicit probability information to make meaningful decisions. Using these cues, we measured probability distortion from choices between the gambles and safe rewards. Parametric modeling of the choices revealed classic probability weighting functions with inverted-S shape. Therefore, the animals overweighted low probability rewards and underweighted high probability rewards. Empirical investigation of the behavior verified that the choices were best explained by a combination of nonlinear value and nonlinear probability distortion. Together, these results suggest that probability distortion may reflect evolutionarily preserved neuronal processing.

  15. The distortion tensor of magnetotellurics: a tutorial on some properties

    NASA Astrophysics Data System (ADS)

    Lilley, Frederick E. M.

    2016-05-01

    A 2 × 2 matrix is introduced which relates the electric field at an observing site where geological distortion applies to the regional electric field, which is unaffected by the distortion. For the student of linear algebra this matrix provides a practical example with which to demonstrate the basic and important procedures of eigenvalue analysis and singular value decomposition. The significance of the results can be visualised because the eigenvectors of such a telluric distortion matrix have a clear practical meaning, as do their eigenvalues. A Mohr diagram for the distortion matrix displays when real eigenvectors exist, and tells their magnitudes and directions. The results of singular value decomposition (SVD) also have a clear practical meaning. These results too can be displayed on a Mohr diagram. Whereas real eigenvectors may or may not exist, SVD is always possible. The ratio of the two singular values of the matrix gives a condition number, useful to quantify distortion. Strong distortion causes the matrix to approach the condition known as `singularity'. A closely-related anisotropy number may also be useful, as it tells when a 2 × 2 matrix has a negative determinant by then having a value greater than unity.

  16. Economic Choices Reveal Probability Distortion in Macaque Monkeys

    PubMed Central

    Lak, Armin; Bossaerts, Peter; Schultz, Wolfram

    2015-01-01

    Economic choices are largely determined by two principal elements, reward value (utility) and probability. Although nonlinear utility functions have been acknowledged for centuries, nonlinear probability weighting (probability distortion) was only recently recognized as a ubiquitous aspect of real-world choice behavior. Even when outcome probabilities are known and acknowledged, human decision makers often overweight low probability outcomes and underweight high probability outcomes. Whereas recent studies measured utility functions and their corresponding neural correlates in monkeys, it is not known whether monkeys distort probability in a manner similar to humans. Therefore, we investigated economic choices in macaque monkeys for evidence of probability distortion. We trained two monkeys to predict reward from probabilistic gambles with constant outcome values (0.5 ml or nothing). The probability of winning was conveyed using explicit visual cues (sector stimuli). Choices between the gambles revealed that the monkeys used the explicit probability information to make meaningful decisions. Using these cues, we measured probability distortion from choices between the gambles and safe rewards. Parametric modeling of the choices revealed classic probability weighting functions with inverted-S shape. Therefore, the animals overweighted low probability rewards and underweighted high probability rewards. Empirical investigation of the behavior verified that the choices were best explained by a combination of nonlinear value and nonlinear probability distortion. Together, these results suggest that probability distortion may reflect evolutionarily preserved neuronal processing. PMID:25698750

  17. Effects of Distortion on Mass Flow Plug Calibration

    NASA Technical Reports Server (NTRS)

    Sasson, Jonathan; Davis, David O.; Barnhart, Paul J.

    2015-01-01

    A numerical, and experimental investigation to study the effects of flow distortion on a Mass Flow Plug (MFP) used to control and measure mass-flow during an inlet test has been conducted. The MFP was first calibrated using the WIND-US flow solver for uniform (undistorted) inflow conditions. These results are shown to compare favorably with an experimental calibration under similar conditions. The effects of distortion were investigated by imposing distorted flow conditions taken from an actual inlet test to the inflow plane of the numerical simulation. The computational fluid dynamic (CFD) based distortion study only showed the general trend in mass flow rate. The study used only total pressure as the upstream boundary condition, which was not enough to define the flow. A better simulation requires knowledge of the turbulence structure and a specific distortion pattern over a range of plug positions. It is recommended that future distortion studies utilize a rake with at least the same amount of pitot tubes as the AIP rake.

  18. Factors associated with body image distortion in Korean adolescents

    PubMed Central

    Hyun, Mi-Yeul; Jung, Young-Eun; Kim, Moon-Doo; Kwak, Young-Sook; Hong, Sung-Chul; Bahk, Won-Myong; Yoon, Bo-Hyun; Yoon, Hye Won; Yoo, Bora

    2014-01-01

    Purpose Body image incorporates cognitive and affective components as well as behaviors related to own body perception. This study evaluated the occurrence of body image distortion and its correlates in Korean adolescents. Methods In a school-based cross-sectional survey, a total of 2,117 adolescents were recruited. They filled out self-completing questionnaires on body image distortion, eating attitudes, and behaviors (Eating Attitude Test-26) and related factors. Results Body image distortions were found in 51.8 percent of adolescents. Univariate analyses showed that boys and older adolescents had higher rates of body image distortion. In the multivariate analyses, body image distortion was associated with high risk for eating disorders (odds ratio [OR] =1.69; 95% confidence interval [CI] 1.11–2.58; P=0.015) and being over weight (OR =33.27; 95% CI 15.51–71.35; P<0.001) or obese (OR =9.37; 95% CI 5.06–17.34; P<0.001). Conclusion These results suggest that body image distortion is relatively common in Korean adolescents, which has implications for adolescents at risk of developing eating disorders. PMID:24868156

  19. Rate distortion analysis for spatially scalable video coding.

    PubMed

    Zhang, Rong; Comer, Mary L

    2010-11-01

    In this paper, we derive the rate distortion lower bounds of spatially scalable video coding techniques. The methods we evaluate are subband and pyramid motion compensation where temporal redundancies in the same spatial layer as well as interlayer spatial redundancies are exploited in the enhancement layer encoding. The rate distortion bounds are derived from rate distortion theory for stationary Gaussian signals where mean square error is used as the distortion criteria. Assuming that the base layer is encoded by a non-scalable video coder, we derive the rate distortion functions for the enhancement layer, which depend on the power spectral density of the input signal, the motion prediction error probability density function and the base layer encoding performance. We will show that pyramid and subband methods are expected to outperform independently encoding the enhancement layer using motion-compensated prediction, in terms of rate distortion efficiency, when the base layer is encoded at a relatively higher quality or less accurate displacement estimation happens in the enhancement layer. PMID:20519155

  20. Inlet distortion effects in aircraft propulsion system integration

    NASA Technical Reports Server (NTRS)

    Longley, J. P.; Greitzer, E. M.

    1992-01-01

    A tutorial survey of inlet flow distortion effects on engine performance and stability is presented. Inlet distortions in aero engines arise through a variety of causes. They can be essentially steady, due to non-axisymmetric intake duct geometry, or time varying, for example from flow separation off the lip of the inlet during maneuvers or shock-induced separation during supersonic flight. Whatever the cause, the result is generally a decrease in performance and, more importantly, a lessening of the stable flow range of the compressor. The distortions are generally three-dimensional. It is an extremely useful simplification to break them, at least conceptually, into radial and circumferential non-uniformities and approach each separately. Purely radial distortions can be treated by the methods that were developed for designing compressors in nominally axisymmetric inlet flow, and this type of distortion will be only briefly discussed. Circumferential non-uniformities, however, introduce additional fluid dynamic features into the analysis of compressor behavior and often have the larger impact on performance and stability. Thus we concentrate mainly on the effects of steady circumferential inlet flow distortion.

  1. Hierarchical temporal processing deficit model of reality distortion and psychoses.

    PubMed

    Krishnan, R R; Fivaz, M; Kraus, M S; Keefe, R S E

    2011-02-01

    We posit in this article that hierarchical temporal processing deficit is the underlying basis of reality distortion and psychoses. Schizophrenia is a prototypical reality distortion disorder in which the patient manifests with auditory hallucinations, delusions, disorganized speech and thinking, cognitive impairment, avolition and social and occupational dysfunction. Reality distortion can be present in many other disorders including bipolar disorder, major depression and even dementia. Conceptually, schizophrenia is a heterogeneous entity likely to be because of numerous causes similar to dementia. Although no single symptom or set of symptoms is pathognomonic, a cardinal feature in all patients with schizophrenia is chronic distortion of reality. The model that we have proposed accounts for the varied manifestations of reality distortion including hallucinations and delusions. In this paper we consider the implications of this model for the underlying biology of psychoses and also for the neurobiology of schizophrenia and suggest potential targets to consider for the etiology and pathophysiology of reality distortion, especially in the context of schizophrenia.

  2. Elastic multipoles in the field of the nematic director distortions.

    PubMed

    Pergamenshchik, V M

    2014-12-01

    Theory of the interaction between all types of elastic dipoles and quadrupoles and distortions of the nematic director is presented. If a particle is small relative to the characteristic distortion length, the interaction is determined by the director derivatives at the particle location. We consider a spherical particle since, even under the standard assumptions of the multipole theory (weak deformations, one constant approximation), the problem can be solved analytically only in this case. Different dipoles interact with different distortion modes (e.g., isotropic dipole interacts with the splay, chiral dipole with the twist, and so on). In the main order, the interaction of a dipole is linear in the director derivatives, and the interaction of a quadrupole is linear in the second-order director derivatives. The theory goes beyond the main-order terms and predicts an effective distortion-induced dipolar component on a particle. This effect is described by the free energy term quadratic in the director derivatives and has contributions both of a bulk and surface origin. The bulk effect takes place even if the director at the particle surface is fixed, whereas the surface effect appears if the surface director is perturbed by the distortions due to a weak surface anchoring. The theory is illustrated by simple examples of the interaction of elastic dipoles with a disclination line, with cholesteric spiral, and with the director distortions in a hybrid cell.

  3. Wave propagation analysis using the variance matrix.

    PubMed

    Sharma, Richa; Ivan, J Solomon; Narayanamurthy, C S

    2014-10-01

    The propagation of a coherent laser wave-field through a pseudo-random phase plate is studied using the variance matrix estimated from Shack-Hartmann wavefront sensor data. The uncertainty principle is used as a tool in discriminating the data obtained from the Shack-Hartmann wavefront sensor. Quantities of physical interest such as the twist parameter, and the symplectic eigenvalues, are estimated from the wavefront sensor measurements. A distance measure between two variance matrices is introduced and used to estimate the spatial asymmetry of a wave-field in the experiment. The estimated quantities are then used to compare a distorted wave-field with its undistorted counterpart. PMID:25401243

  4. More flexibility in representing geometric distortion in astronomical images

    NASA Astrophysics Data System (ADS)

    Shupe, David L.; Laher, Russ R.; Storrie-Lombardi, Lisa; Surace, Jason; Grillmair, Carl; Levitan, David; Sesar, Branimir

    2012-09-01

    A number of popular software tools in the public domain are used by astronomers, professional and amateur alike, but some of the tools that have similar purposes cannot be easily interchanged, owing to the lack of a common standard. For the case of image distortion, SCAMP and SExtractor, available from Astromatic.net, perform astrometric calibration and source-object extraction on image data, and image-data geometric distortion is computed in celestial coordinates with polynomial coefficients stored in the FITS header with the PV i_j keywords. Another widely-used astrometric-calibration service, Astrometry.net, solves for distortion in pixel coordinates using the SIP convention that was introduced by the Spitzer Science Center. Up until now, due to the complexity of these distortion representations, it was very difficult to use the output of one of these packages as input to the other. New Python software, along with faster-computing C-language translations, have been developed at the Infrared Processing and Analysis Center (IPAC) to convert FITS-image headers from PV to SIP and vice versa. It is now possible to straightforwardly use Astrometry.net for astrometric calibration and then SExtractor for source-object extraction. The new software also enables astrometric calibration by SCAMP followed by image visualization with tools that support SIP distortion, but not PV . The software has been incorporated into the image-processing pipelines of the Palomar Transient Factory (PTF), which generate FITS images with headers containing both distortion representations. The software permits the conversion of archived images, such as from the Spitzer Heritage Archive and NASA/IPAC Infrared Science Archive, from SIP to PV or vice versa. This new capability renders unnecessary any new representation, such as the proposed TPV distortion convention.

  5. Comparing Distortion Product Otoacoustic Emissions to Intracochlear Distortion Products Inferred from a Noninvasive Assay.

    PubMed

    Martin, Glen K; Stagner, Barden B; Dong, Wei; Lonsbury-Martin, Brenda L

    2016-08-01

    The behavior of intracochlear distortion products (iDPs) was inferred by interacting a probe tone (f3) with the iDP of interest to produce a "secondary" distortion product otoacoustic emission termed DPOAE(2ry). Measures of the DPOAE(2ry) were then used to deduce the properties of the iDP. This approach was used in alert rabbits and anesthetized gerbils to compare ear-canal 2f1-f2 and 2f2-f1 DPOAE f2/f1 ratio functions, level/phase (L/P) maps, and interference-response areas (IRAs) to their simultaneously collected DPOAE(2ry) counterparts. These same measures were also collected in a human volunteer to demonstrate similarities with their laboratory animal counterparts and their potential applicability to humans. Results showed that DPOAEs and inferred iDPs evidenced distinct behaviors and properties. That is, DPOAE ratio functions elicited by low-level primaries peaked around an f2/f1 = 1.21 or 1.25, depending on species, while the corresponding inferred iDP ratio functions peaked at f2/f1 ratios of ~1. Additionally, L/P maps showed rapid phase variation with DPOAE frequency (fdp) for the narrow-ratio 2f1-f2 and all 2f2-f1 DPOAEs, while the corresponding DPOAE(2ry) measures evidenced relatively constant phases. Common features of narrow-ratio DPOAE IRAs, such as large enhancements for interference tones (ITs) presented above f2, were not present in DPOAE(2ry) IRAs. Finally, based on prior experiments in gerbils, the behavior of the iDP directly measured in intracochlear pressure was compared to the iDP inferred from the DPOAE(2ry) and found to be similar. Together, these findings are consistent with the notion that under certain conditions, ear-canal DPOAEs provide poor representations of iDPs and thus support a "beamforming" hypothesis. According to this concept, distributed emission components directed toward the ear canal from the f2 and basal to f2 regions can be of differing phases and thus cancel, while these same components directed toward fdp add in

  6. Near-surface and topographic distortions in electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Jiracek, George R.

    1990-09-01

    The most revealing description of electromagnetic (EM) distortions due to near-surface inhomogeneities and topography is in terms of galvanic and inductive effects. In either case, the distorted electric and magnetic fields can be best visualized as a vectorial sum of primary and secondary fields. Secondary electric fields due to electric charge build-up in the galvanic case persist to the longest periods. In contrast, the secondary electric and magnetic fields due to inductive, vortex currents disappear at long periods. The static shift of magnetotelluric (MT) apparent resistivity sounding curves is a classic example of the galvanic effect. Methods to correct for unwanted distortions such as the static shift can be classified into six categories: use of invariant response parameters, curve shifting, statistical averaging, spatial filtering, use of distortion tensors, and computer modeling. Although invariant impedance calculations are simple to make, they cannot, in general, recover the undistorted impedance. Short period curve shifting is best done with auxiliary soundings such as time domain EM; however, this requires multiple surveys. The shifting of long period MT sounding branches is useful if a standard curve is known and can be matched. Statistical averaging of neighboring MT soundings that are conformal but static shifted has proven very effective at removing random distortions if adaquate data are available. The new EMAP (Electromagnetic Array Profiling) method combats the inherent spatial high pass characteristics of EM distortions by low pass operations in data collection and processing. EMAP proposes the continuous, in-field measurement of electric field dipoles to avoid spatial aliasing. Distortion tensor stripping of topographic distortions is possible since terrain is deterministic but stripping the effects of uncertain subsurface inhomogeneities may be misleading. A new decomposition of the MT impedance tensor under the assumption of surficial

  7. Noise Shaping Filter Compensating PWM Distortion for Fully Digital Amplifier

    NASA Astrophysics Data System (ADS)

    Yoneya, Akihiko

    The full-digital audio amplifiers have several merits such as a high power enabling a small size of the amplifier and digital implementation of the signal processing which allows desired precision of the processing except for the final stage switching amplifiers. Unfortunately, the pulse width modulation (PWM) causes signal distortions because of the non-linearity of the modulation from the viewpoint of the transient response. This paper proposes a compensation method of the PWM distortion with feedback approach. In the noise-shaping filter of the delta-sigma modulator to calculate the pulse codes for the PWM, the distortion caused by the PWM is evaluated and fed it back to compensate the distortion. Eventually the filter is implemented as a state-variable filter with non-linear feedback from the quantizer. The calculation of the filter elements is also described. By using proposed filters, PWM signals with small distortions and small floor noise can be obtained to realize high-fidelity audio amplifiers.

  8. Short-Term Changes in Light Distortion in Orthokeratology Subjects

    PubMed Central

    Santolaria Sanz, Elena; Villa-Collar, Cesar; González-Méijome, Jose Manuel

    2015-01-01

    Purpose. Quantifying adaptation to light distortion of subjects undergoing orthokeratology (OK) for myopia during the first month of treatment. Methods. Twenty-nine healthy volunteers (age: 22.34 ± 8.08 years) with mean spherical equivalent refractive error −2.10 ± 0.93D were evaluated at baseline and days 1, 7, 15, and 30 of OK treatment. Light distortion was determined using an experimental prototype. Corneal aberrations were derived from corneal topography for different pupil sizes. Contrast sensitivity function (CSF) was analyzed for frequencies of 1.50, 2.12, 3.00, 4.24, 6.00, 8.49, 12.00, 16.97, and 24.00 cpd under photopic conditions. Results. Average monocular values of all light distortion parameters measured increased significantly on day 1, returning to baseline after 1 week (P < 0.05 in all cases). Spherical-like aberration stabilized on day 7 for all pupil diameters, while coma-like for smaller pupils only. CSF was significantly reduced on day 1 for all spatial frequencies except for 1.5 cpd, returning to baseline afterwards. Significant correlation was found between light distortion and contrast sensitivity for middle and high frequencies (P < 0.05) after 15 days. Conclusion. Despite consistently increased levels of corneal aberrations, light distortion tends to return to baseline after one week of treatment, suggesting that neural adaptation is capable of overcoming optical quality degradation. PMID:25699265

  9. Detection of architectural distortion in mammograms using phase portraits

    NASA Astrophysics Data System (ADS)

    Ayres, Fabio J.; Rangayyan, Rangaraj M.

    2004-05-01

    Architectural distortion is a subtle abnormality in mammograms, and a source of overlooking errors by radiologists. Computer-aided diagnosis (CAD) techniques can improve the performance of radiologists in detecting masses and calcifications; however, most CAD systems have not been designed to detect architectural distortion. We present a new method to detect and localize architectural distortion by analyzing the oriented texture in mammograms. A bank of Gabor filters is used to obtain the orientation field of the given mammogram. The orientation field is filtered and downsampled, to reduce noise and also to reduce the computational effort required by the subsequent methods. The downsampled orientation field is analyzed to produce three phase portrait maps: node, saddle, and spiral. The node map is linearly filtered, thresholded, and morphologically filtered to detect architectural distortion. The method was tested with 18 mammograms containing architectural distortion. In a preliminary experiment, a sensitivity of 88% was obtained at 15 false positives per image. Several possibilities for the improvement of the technique are being explored. A qualitative analysis of the performance of the method with stellate lesions indicates potential for enhancement of the technique.

  10. Satellite measurement of ionospheric-induced vhf distortion

    SciTech Connect

    Armstrong, W.T.; Murphy, T.; Roussel-Dupre, R.; Carter, M.J.; Blevins, B.

    1992-09-01

    BLACKBEARD is a satellite RF experiment designed to study distortion and interference effects on transient transionospheric VHF signals. RF distortion will be characterized by a frequency-coherence bandwidth for different ionospheric conditions. Limitations of broad-band measurements from the frequency-coherence bandwidth of the ionosphere and broadcast interference signals will be established through these studies. Distinction between multi-path distortion resulting from large scale, coherent perturbations and small scale, random perturbations to the ionosphere will be emphasized. Ionospheric transfer function models, trans-ionospheric signal predictions, and coherence bandwidth predictions will be tested and optimized with these measurements. A global data base for both broadcast and lightning interference will also derive from these studies. This database will form the basis for interference feature extraction, signal typing, and possible neural network cataloging. The specific missions of the BLACKBEARD experiment include: perform broad-band VHF measurements of transient signals originating from a controlled pulsed ground beacon, to characterize broad-band ionospheric distortion, perform narrow-band VHF measurements of cw signals from a multi-chord interferometry ground beacon array, to characterize ionospheric structure contributing to transmission distortion, and survey power envelopes of lightning and man-made interference in selectable VHF bands, for background rejection purposes. BLACKBEARD is part of the ALEMS soft x-ray measurement satellite, a small satellite system designed for a PEGASUS launch into a 70{degrees} inclination, low earth orbit in late 1992.

  11. Satellite measurement of ionospheric-induced vhf distortion

    SciTech Connect

    Armstrong, W.T.; Murphy, T.; Roussel-Dupre, R.; Carter, M.J.; Blevins, B.

    1992-01-01

    BLACKBEARD is a satellite RF experiment designed to study distortion and interference effects on transient transionospheric VHF signals. RF distortion will be characterized by a frequency-coherence bandwidth for different ionospheric conditions. Limitations of broad-band measurements from the frequency-coherence bandwidth of the ionosphere and broadcast interference signals will be established through these studies. Distinction between multi-path distortion resulting from large scale, coherent perturbations and small scale, random perturbations to the ionosphere will be emphasized. Ionospheric transfer function models, trans-ionospheric signal predictions, and coherence bandwidth predictions will be tested and optimized with these measurements. A global data base for both broadcast and lightning interference will also derive from these studies. This database will form the basis for interference feature extraction, signal typing, and possible neural network cataloging. The specific missions of the BLACKBEARD experiment include: perform broad-band VHF measurements of transient signals originating from a controlled pulsed ground beacon, to characterize broad-band ionospheric distortion, perform narrow-band VHF measurements of cw signals from a multi-chord interferometry ground beacon array, to characterize ionospheric structure contributing to transmission distortion, and survey power envelopes of lightning and man-made interference in selectable VHF bands, for background rejection purposes. BLACKBEARD is part of the ALEMS soft x-ray measurement satellite, a small satellite system designed for a PEGASUS launch into a 70{degrees} inclination, low earth orbit in late 1992.

  12. Parametric distortion-adaptive neighborhood for omnidirectional camera.

    PubMed

    Tang, Yazhe; Li, Youfu; Luo, Jun

    2015-08-10

    Catadioptric omnidirectional images exhibit serious nonlinear distortion due to the involved quadratic mirror. Conventional pinhole model-based methods perform poorly when directly applied to the deformed omnidirectional images. This study constructs a catadioptric geometry system to analyze the variation of the neighborhood of an object in terms of the elevation and azimuth directions in a spherical coordinate system. To accurately represent the distorted visual information, a parametric neighborhood mapping model is proposed based on the catadioptric geometry. Unlike the conventional catadioptric models, the prior information of the system is effectively integrated into the neighborhood formulation framework. Then the distortion-adaptive neighborhood can be directly calculated based on its measurable image radial distance. This method can significantly improve the computational efficiency of algorithm since statistical neighborhood sampling is not used. On the basis of the proposed neighborhood model, a distortion-invariant Haar wavelet transform is presented to perform the robust human detection and tracking in catadioptric omnidirectional vision. The experimental results verify the effectiveness of the proposed neighborhood mapping model and prove that the distorted neighborhood in the omnidirectional image follows a nonlinear pattern.

  13. Real-time lens distortion correction: speed, accuracy and efficiency

    NASA Astrophysics Data System (ADS)

    Bax, Michael R.; Shahidi, Ramin

    2014-11-01

    Optical lens systems suffer from nonlinear geometrical distortion. Optical imaging applications such as image-enhanced endoscopy and image-based bronchoscope tracking require correction of this distortion for accurate localization, tracking, registration, and measurement of image features. Real-time capability is desirable for interactive systems and live video. The use of a texture-mapping graphics accelerator, which is standard hardware on current motherboard chipsets and add-in video graphics cards, to perform distortion correction is proposed. Mesh generation for image tessellation, an error analysis, and performance results are presented. It is shown that distortion correction using commodity graphics hardware is substantially faster than using the main processor and can be performed at video frame rates (faster than 30 frames per second), and that the polar-based method of mesh generation proposed here is more accurate than a conventional grid-based approach. Using graphics hardware to perform distortion correction is not only fast and accurate but also efficient as it frees the main processor for other tasks, which is an important issue in some real-time applications.

  14. Distortion definition and correction in off-axis systems

    NASA Astrophysics Data System (ADS)

    Da Deppo, Vania; Simioni, Emanuele; Naletto, Giampiero; Cremonese, Gabriele

    2015-09-01

    Off-axis optical configurations are becoming more and more used in a variety of applications, in particular they are the most preferred solution for cameras devoted to Solar System planets and small bodies (i.e. asteroids and comets) study. Off-axis designs, being devoid of central obstruction, are able to guarantee better PSF and MTF performance, and thus higher contrast imaging capabilities with respect to classical on-axis designs. In particular they are suitable for observing extended targets with intrinsic low contrast features, or scenes where a high dynamical signal range is present. Classical distortion theory is able to well describe the performance of the on-axis systems, but it has to be adapted for the off-axis case. A proper way to deal with off-axis distortion definition is thus needed together with dedicated techniques to accurately measure and hence remove the distortion effects present in the acquired images. In this paper, a review of the distortion definition for off-axis systems will be given. In particular the method adopted by the authors to deal with the distortion related issues (definition, measure, removal) in some off-axis instruments will be described in detail.

  15. Recovery of motion parameters from distortions in scanned images

    NASA Technical Reports Server (NTRS)

    Mulligan, Jeffrey B.

    1997-01-01

    Scanned images, such as those produced by the scanning-laser ophthalmoscope (SLO), show distortions when there is target motion. This is because pixels corresponding to different image regions are acquired sequentially, and so, in essence, are slices of different snapshots. While these distortions create problems for image registration algorithms, they are potentially useful for recovering target motion parameters at temporal frequencies above the frame rate. Stetter, Sendtner and Timberlake measured large distortions in SLO images to recover the time course of rapid horizontal saccadic eye movements. Here, this work is extended with the goal of automatically recovering small eye movements in two dimensions. Eye position during the frame interval is modeled using a low dimensional parametric description, which in turn is used to generate predicted distortions of a reference template. The input image is then registered to the distorted template using normalized cross correlation. The motion parameters are then varied, and the correlation recomputed, to find the motion which maximizes the peak value of the correlation. The location and value of the correlation maximum are determined with sub-pixel precision using biquadratic interpolation, yielding eye position resolution better than 1 arc minute. This method of motion parameter estimation is tested using actual SLO images as well as simulated images. Motion parameter estimation might also be applied to individual video lines in order to reduce pipeline delays for a near real-time system.

  16. Should sex-ratio distorting parasites abandon horizontal transmission?

    PubMed Central

    2011-01-01

    Background Sex-ratio distorting parasites are of interest due to their effects upon host population dynamics and their potential to influence the evolution of host sex determination systems. In theory, the ability to distort host sex-ratios allows a parasite with efficient vertical (hereditary) transmission to dispense completely with horizontal (infectious) transmission. However, recent empirical studies indicate that some sex-ratio distorting parasites have retained the capability for horizontal transmission. Results Numerical simulations using biologically realistic parameters suggest that a feminising parasite is only likely to lose the capability for horizontal transmission if its host occurs at low density and/or has a male-biased primary sex ratio. It is also demonstrated that even a small amount of horizontal transmission can allow multiple feminising parasites to coexist within a single host population. Finally it is shown that, by boosting its host's rate of population growth, a feminising parasite can increase its own horizontal transmission and allow the invasion of other, more virulent parasites. Conclusions The prediction that sex-ratio distorting parasites are likely to retain a degree of horizontal transmission has important implications for the epidemiology and host-parasite interactions of these organisms. It may also explain the frequent co-occurrence of several sex-ratio distorting parasite species in nature. PMID:22188680

  17. Shear waves in inhomogeneous, compressible fluids in a gravity field.

    PubMed

    Godin, Oleg A

    2014-03-01

    While elastic solids support compressional and shear waves, waves in ideal compressible fluids are usually thought of as compressional waves. Here, a class of acoustic-gravity waves is studied in which the dilatation is identically zero, and the pressure and density remain constant in each fluid particle. These shear waves are described by an exact analytic solution of linearized hydrodynamics equations in inhomogeneous, quiescent, inviscid, compressible fluids with piecewise continuous parameters in a uniform gravity field. It is demonstrated that the shear acoustic-gravity waves also can be supported by moving fluids as well as quiescent, viscous fluids with and without thermal conductivity. Excitation of a shear-wave normal mode by a point source and the normal mode distortion in realistic environmental models are considered. The shear acoustic-gravity waves are likely to play a significant role in coupling wave processes in the ocean and atmosphere.

  18. Shear waves in inhomogeneous, compressible fluids in a gravity field.

    PubMed

    Godin, Oleg A

    2014-03-01

    While elastic solids support compressional and shear waves, waves in ideal compressible fluids are usually thought of as compressional waves. Here, a class of acoustic-gravity waves is studied in which the dilatation is identically zero, and the pressure and density remain constant in each fluid particle. These shear waves are described by an exact analytic solution of linearized hydrodynamics equations in inhomogeneous, quiescent, inviscid, compressible fluids with piecewise continuous parameters in a uniform gravity field. It is demonstrated that the shear acoustic-gravity waves also can be supported by moving fluids as well as quiescent, viscous fluids with and without thermal conductivity. Excitation of a shear-wave normal mode by a point source and the normal mode distortion in realistic environmental models are considered. The shear acoustic-gravity waves are likely to play a significant role in coupling wave processes in the ocean and atmosphere. PMID:24606251

  19. A Density Functional Equation of State for Supernova Simulations with 3-body forces and Quark Gluon Plasma

    NASA Astrophysics Data System (ADS)

    Mathews, Grant J.; Meixner, Matthew; Olson, J. Pocahontas; Lan, Nguyen Q.; Dalhed, Holister E.

    2013-10-01

    We present an updated and improved equation of state (which we call the NDL EoS) for use in neutron-star structure and core-collapse supernova simulations. This EoS is begins with a framework originally developed by Bowers & Wilson, but there are numerous changes. Among them are: (1) a reformulation in the context of density functional theory; (2) the possibility of the formation of material with a net proton excess (Ye > 0 . 5); (3) an improved treatment of the nuclear statistical equilibrium and the transition to heavy nuclei as the density approaches nuclear matter density; (4) an improved treatment of the effects of pions in the regime above nuclear matter density including the incorporation of all the known mesonic and baryonic states at high temperature; (5) the effects of 3-body nuclear forces at high densities; and (6) the possibility of a first-order or crossover transition to a QCD chiral symmetry restoration and deconfinement phase at densities above nuclear matter density. This paper details the physics of, and constraints on, this new EoS and describes its implementation in numerical simulations. We show comparisons of this EoS with other equations of state commonly used in supernova collapse simulations. Work at the University of Notre Dame is supported by the U.S. Department of Energy under Nuclear Theory Grant DE-FG02-95-ER40934.

  20. Intrinsic nonlinearity probed by intermodulation distortion microwave measurements on high quality MgB2 thin films

    NASA Astrophysics Data System (ADS)

    Cifariello, G.; Aurino, M.; Di Gennaro, E.; Lamura, G.; Andreone, A.; Orgiani, P.; Xi, X. X.; Villégier, J.-C.

    2006-04-01

    The two-tone intermodulation distortion arising in MgB2 thin films synthesized by hybrid physical-chemical vapor deposition is studied in order to probe the influence of the two bands on the nonlinear response of this superconductor. The measurements are carried out by using a dielectrically loaded copper cavity operating at 7GHz. Microwave data on samples having critical temperatures above 41K, very low resistivity values, and residual resistivity ratio larger than 10 are shown. The dependence of the nonlinear surface losses and of the third order intermodulation products on the power feeding the cavity and on the temperature is analyzed. At low power, the signal arising from distortion versus temperature shows the intrinsic s-wave behavior expected for this compound. Data are compared with measurements performed on Nb and YBa2Cu3O7-δ thin films using the same technique.

  1. Wave turbulence

    NASA Astrophysics Data System (ADS)

    Nazarenko, Sergey

    2015-07-01

    Wave turbulence is the statistical mechanics of random waves with a broadband spectrum interacting via non-linearity. To understand its difference from non-random well-tuned coherent waves, one could compare the sound of thunder to a piece of classical music. Wave turbulence is surprisingly common and important in a great variety of physical settings, starting with the most familiar ocean waves to waves at quantum scales or to much longer waves in astrophysics. We will provide a basic overview of the wave turbulence ideas, approaches and main results emphasising the physics of the phenomena and using qualitative descriptions avoiding, whenever possible, involved mathematical derivations. In particular, dimensional analysis will be used for obtaining the key scaling solutions in wave turbulence - Kolmogorov-Zakharov (KZ) spectra.

  2. Distorted segregation in plant hybrids and its implication for evolution.

    PubMed

    Zhe, Wang

    2016-09-01

    During natural hybridization and introgression, offspring may obtain alleles from both parents unevenly, resulting in allelic segregation that significantly deviated from the Mendelian ratio, referred to as segregation distortion (SD). Segregation distortion is a common phenomenon and a number of factors can influence the ratio and pattern of segregation distortion in hybrid descendants. However, knowledge on the evolutionary implication of SD is still very limited. In this review, we summarize the current knowledge regarding mechanisms of SD such as genetic interaction, genetic divergence, cytoplasmic background, and environmental effect, and analyze its implication for evolution. In short, SD affects evolutionary potential, sex ratio, genetic diversity and maintenance of stable genetic divergence. Therefore, the effect of transgene on the evolutionary potential of wild relative populations through SD and the changes of the pattern of SD in continuous generations should be paid attention to in future studies. PMID:27644741

  3. Constitutive modelling of evolving flow anisotropy including distortional hardening

    SciTech Connect

    Pietryga, Michael P.; Vladimirov, Ivaylo N.; Reese, Stefanie

    2011-05-04

    The paper presents a new constitutive model for anisotropic metal plasticity that takes into account the expansion or contraction (isotropic hardening), translation (kinematic hardening) and change of shape (distortional hardening) of the yield surface. The experimentally observed region of high curvature ('nose') on the yield surface in the loading direction and flattened shape in the reverse loading direction are modelled here by means of the concept of directional distortional hardening. The modelling of directional distortional hardening is accomplished by means of an evolving fourth-order tensor. The applicability of the model is illustrated by fitting experimental subsequent yield surfaces at finite plastic deformation. Comparisons with test data for aluminium low and high work hardening alloys display a good agreement between the simulation results and the experimental data.

  4. Predictive Rate-Distortion for Infinite-Order Markov Processes

    NASA Astrophysics Data System (ADS)

    Marzen, Sarah E.; Crutchfield, James P.

    2016-06-01

    Predictive rate-distortion analysis suffers from the curse of dimensionality: clustering arbitrarily long pasts to retain information about arbitrarily long futures requires resources that typically grow exponentially with length. The challenge is compounded for infinite-order Markov processes, since conditioning on finite sequences cannot capture all of their past dependencies. Spectral arguments confirm a popular intuition: algorithms that cluster finite-length sequences fail dramatically when the underlying process has long-range temporal correlations and can fail even for processes generated by finite-memory hidden Markov models. We circumvent the curse of dimensionality in rate-distortion analysis of finite- and infinite-order processes by casting predictive rate-distortion objective functions in terms of the forward- and reverse-time causal states of computational mechanics. Examples demonstrate that the resulting algorithms yield substantial improvements.

  5. Self-induced thermal distortion effects on target image quality.

    PubMed

    Gebhardt, F G

    1972-06-01

    Experimental results are reported that show the effects of the self-induced thermal lens due to a high power laser beam on imaging or tracking systems viewing along the same propagation path. The thermal distortion effects of a wind are simulated with a low power ( less, similar 3-W) CO(2) laser beam propagating through a cell of liquid CS(2) moving across the beam. The resulting image distortion includes a warping effect analogous to the deflection of the CO(2) beam, together with a pronounced demagnification of the central portion of the object. An active optical tracker is simulated with a He-Ne laser beam propagating collinearly with the CO(2) beam. The He-Ne beam pattern returned from a specular target is distorted and sharply confined to the outline of the crescent shaped CO(2) beam. Simple ray optics models are used to provide qualitative explanations for the experimental results.

  6. Tunable molecular distortion in crystals with a supramolecular aggregate

    SciTech Connect

    Falvello, L.R.; Pascual, I.; Palacio, F.

    1996-12-31

    Crystals of trans-[Ni(cyan-N){sub 2}(NH{sub 3}){sub 4}], which possess a stable supramolecular ribbon by cyanurate ligands, undergo a reversible, non-destructive, temperature-induced phase transition. At room temperature, the crystals are orthorhombic, space group Fmmm, with the molecule on a site of D{sub 2h} (mmm) symmetry. At 20 K, the crystals possess the same orthorhombic unit cell, but have space group Cmcm; the molecule has symmetry C{sub 2v} (m2m), and is distorted by bending of the cyanurate rings out of their common plane. At intermediate temperatures, an intermediate distorted structure emerges. Structural characterizations by x-ray or neutron diffraction at five temperatures from 20 to 298 K are presented. Changes in the electronic spectrum of the compound accompany the temperature-dependent distortion of the molecule. Magnetic measurements indicate that the compound orders as an antiferromagnet at about 3 K.

  7. Pulsar Pair Cascades in a Distorted Magnetic Dipole Field

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.; Muslimov, Alex G.

    2010-01-01

    We investigate the effect of a distorted neutron star dipole magnetic field on pulsar pair cascade multiplicity and pair death lines. Using a simple model for a distorted dipole field that produces an offset polar cap (PC), we derive the accelerating electric field above the PC in space-charge-limited flow. We find that even a modest azimuthally asymmetric distortion can significantly increase the accelerating electric field on one side of the PC and, combined with a smaller field line radius of curvature, leads to larger pair multiplicity. The death line for producing pairs by curvature radiation moves downward in the P-P-dot diagram, allowing high pair multiplicities in a larger percentage of the radio pulsar population. These results could have important implications for the radio pulsar population, high energy pulsed emission, and the pulsar contribution to cosmic ray positrons.

  8. Characterizing imaging distortion for the Intermediate Palomar Transient Factory

    NASA Astrophysics Data System (ADS)

    Shupe, David L.; Laher, Russ; Masci, Frank J.; Surace, Jason A.; Bellm, Eric Christopher; Miller, Adam; Ofek, Eran; Intermediate Palomar Transient Factory Collaboration

    2016-01-01

    The advent of time-domain surveys has put a premium on accurate astrometry determined in near-real-time. The Intermediate Palomar Transient Factory (iPTF) employs astrometric solvers from SCAMP in the Astromatic suite and from Astrometry.net. Distortion is computed by these solvers for each individual image and exposure. We present an analysis of the distortion solutions in iPTF data, and some approaches for improving astrometry for iPTF and the upcoming Zwicky Transient Facility. Additionally, Astrometry.net currently uses the SIP convention to represent distortion in FITS image headers, while the Astromatic suite uses the TPV convention. We describe a conversion between between these two conventions which has now been extended to 7th-order polynomials.

  9. Rise-Time Distortion of Signal without Carrying Signal

    NASA Astrophysics Data System (ADS)

    Bukhman, N. S.

    2016-08-01

    The article deals with one-dimensional problem of rise-time distortion signal without carrying signal, that appears in the starting point intermittently, that is signal distortion at front edge or one of its derivative. The authors show that front edge of signal isn't distorted in case of propagation in unrestricted (including absorbing) area (amplitude of starting signal step or of one of its derivatives doesn't change) and move with the accuracy of vacuum light speed. The paper proves that it is the time interval shortage that causes signal loss with the route extension, but not the reduction of its starting amplitude, during which front edge of signal retains its starting value. The research presents new values for this time interval.

  10. Cosmic Microwave Background spectral distortions from cosmic string loops

    NASA Astrophysics Data System (ADS)

    Anthonisen, Madeleine; Brandenberger, Robert; Laguë, Alex; Morrison, Ian A.; Xia, Daixi

    2016-02-01

    Cosmic string loops contain cusps which decay by emitting bursts of particles. A significant fraction of the released energy is in the form of photons. These photons are injected non-thermally and can hence cause spectral distortions of the Cosmic Microwave Background (CMB). Under the assumption that cusps are robust against gravitational back-reaction, we compute the fractional energy density released as photons in the redshift interval where such non-thermal photon injection causes CMB spectral distortions. Whereas current constraints on such spectral distortions are not strong enough to constrain the string tension, future missions such as the PIXIE experiment will be able to provide limits which rule out a range of string tensions between G μ ~ 10-15 and G μ ~ 10-12, thus ruling out particle physics models yielding these kind of intermediate-scale cosmic strings.

  11. An Exact Formula for Calculating Inverse Radial Lens Distortions

    PubMed Central

    Drap, Pierre; Lefèvre, Julien

    2016-01-01

    This article presents a new approach to calculating the inverse of radial distortions. The method presented here provides a model of reverse radial distortion, currently modeled by a polynomial expression, that proposes another polynomial expression where the new coefficients are a function of the original ones. After describing the state of the art, the proposed method is developed. It is based on a formal calculus involving a power series used to deduce a recursive formula for the new coefficients. We present several implementations of this method and describe the experiments conducted to assess the validity of the new approach. Such an approach, non-iterative, using another polynomial expression, able to be deduced from the first one, can actually be interesting in terms of performance, reuse of existing software, or bridging between different existing software tools that do not consider distortion from the same point of view. PMID:27258288

  12. Cognitive distortions of religious professionals who sexually abuse children.

    PubMed

    Saradjian, Adam; Nobus, Dany

    2003-08-01

    This study uses grounded theory to investigate the cognitive distortions in the self-report statements of 14 clergymen who had sexually abused children. These clergy were residents at an assessment and treatment center for child molesters. The content of the offenders'cognitive distortions was identified and categorized into thematic groups. These categories were found to relate to the various stages of the offending cycle. A tentative model was generated that illustrates the relationship between the categories and the hypothesized sequence of thought facilitating the initiation and maintenance of sexually abusive behavior In addition, a number of cognitive processes were identified as contributing to offenders' beliefs. The study also reveals that the clergymen used their religious role and relationship with God within their distorted beliefs. These beliefs were predominantly concentrated in the areas of giving themselves permission to offend, denial of likelihood of getting caught, reduction of guilt after offending, and maintaining a positive sense of self.

  13. The Interpersonal Cognitive Distortions Scale: development and psychometric characteristics.

    PubMed

    Hamamci, Zeynep; Büyüköztürk, Sener

    2004-08-01

    In this study, an Interpersonal Cognitive Distortions Scale was developed to assess cognitive distortions in individuals' interpersonal relationships. The sample comprised 425 university students. A factor analysis yielded three factors: Interpersonal Rejection, Unrealistic Relationship Expectation and Interpersonal Misperception. To examine construct validity the correlations between the scores on the Interpersonal Cognitive Distortions Scale and the Automatic Thoughts Scale (.54), the Irrational Belief Scale (.54), and the Conflict Tendency Scale (.53) were estimated. The first factor, the second factor, and the total scale discriminated married individuals who had low and high conflict intensity and conflict frequency. The reliability of the scale was estimated by performing a test-retest correlation (.74). Cronbach internal consistency coefficient alpha was .67.

  14. Effect of visual distortion on postural balance in a full immersion stereoscopic environment

    NASA Astrophysics Data System (ADS)

    Faubert, Jocelyn; Allard, Remy

    2004-05-01

    This study attempted to determine the influence of non-linear visual movements on our capacity to maintain postural control. An 8x8x8 foot CAVE immersive virtual environment was used. Body sway recordings were obtained for both head and lower back (lumbar 2-3) positions. The subjects were presented with visual stimuli for periods of 62.5 seconds. Subjects were asked to stand still on one foot while viewing stimuli consisting of multiplied sine waves generating movement undulation of a textured surface (waves moving in checkerboard pattern). Three wave amplitudes were tested: 4 feet, 2 feet, and 1 foot. Two viewing conditions were also used; observers looking at 36 inches in front of their feet; observers looking at a distance near the horizon. The results were compiled using an instability index and the data showed a profound and consistent effect of visual disturbances on postural balance in particular for the x (side-to-side) movement. We have demonstrated that non-linear visual distortions similar to those generated by progressive ophthalmic lenses of the kind used for presbyopia corrections, can generate significant postural instability. This instability is particularly evident for the side-to-side body movement and is most evident for the near viewing condition.

  15. Heme Distortions in Sperm-Whale Carbonmonoxy Myoglobin: Correlations between Rotational Strengths and Heme Distortions in MD-Generated Structures

    SciTech Connect

    KIEFL,CHRISTOPH; SCREERAMA,NARASIMHA; LU,YI; QIU,YAN; SHELNUTT,JOHN A.; WOODY,ROBERT W.

    2000-07-13

    The authors have investigated the effects of heme rotational isomerism in sperm-whale carbonmonoxy myoglobin using computational techniques. Several molecular dynamics simulations have been performed for the two rotational isomers A and B, which are related by a 180{degree} rotation around the {alpha}-{gamma} axis of the heme, of sperm-whale carbonmonoxy myoglobin in water. Both neutron diffraction and NMR structures were used as starting structures. In the absence of an experimental structure, the structure of isomer B was generated by rotating the heme in the structure of isomer A. Distortions of the heme from planarity were characterized by normal coordinate structural decomposition and by the angle of twist of the pyrrole rings from the heme plane. The heme distortions of the neutron diffraction structure were conserved in the MD trajectories, but in the NMR-based trajectories, where the heme distortions are less well defined, they differ from the original heme deformations. The protein matrix induced similar distortions on the heroes in orientations A and B. The results suggest that the binding site prefers a particular macrocycle conformation, and a 180{degree} rotation of the heme does not significantly alter the protein's preference for this conformation. The intrinsic rotational strengths of the two Soret transitions, separated according to their polarization in the heme plane, show strong correlations with the ruf-deformation and the average twist angle of the pyrrole rings. The total rotational strength, which includes contributions from the chromophores in the protein, shows a weaker correlation with heme distortions.

  16. Critical Assessment of Correction Methods for Fisheye Lens Distortion

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Tian, C.; Huang, Y.

    2016-06-01

    A fisheye lens is widely used to create a wide panoramic or hemispherical image. It is an ultra wide-angle lens that produces strong visual distortion. The distortion modeling and estimation of the fisheye lens are the crucial step for fisheye lens calibration and image rectification in computer vision and close-range photography. There are two kinds of distortion: radial and tangential distortion. Radial distortion is large for fisheye imaging and critical for the subsequent image processing. Although many researchers have developed calibration algorithms of radial distortion of fisheye lens, quantitative evaluation of the correction performance has remained a challenge. This is the first paper that intuitively and objectively evaluates the performance of five different calibration algorithms. Upto- date research on fisheye lens calibration is comprehensively reviewed to identify the research need. To differentiate their performance in terms of precision and ease-using, five methods are then tested using a diverse set of actual images of the checkerboard that are taken at Wuhan University, China under varying lighting conditions, shadows, and shooting angles. The method of rational function model, which was generally used for wide-angle lens correction, outperforms the other methods. However, the one parameter division model is easy for practical use without compromising too much the precision. The reason is that it depends on the linear structure in the image and requires no preceding calibration. It is a tradeoff between correction precision and ease-using. By critically assessing the strengths and limitations of the existing algorithms, the paper provides valuable insight and guideline for future practice and algorithm development that are important for fisheye lens calibration. It is promising for the optimal design of lens correction models that are suitable for the millions of portable imaging devices.

  17. Rapid computation of the amplitude and phase of tightly focused optical fields distorted by scattering particles

    PubMed Central

    Ranasinghesagara, Janaka C.; Hayakawa, Carole K.; Davis, Mitchell A.; Dunn, Andrew K.; Potma, Eric O.; Venugopalan, Vasan

    2014-01-01

    We develop an efficient method for accurately calculating the electric field of tightly focused laser beams in the presence of specific configurations of microscopic scatterers. This Huygens–Fresnel wave-based electric field superposition (HF-WEFS) method computes the amplitude and phase of the scattered electric field in excellent agreement with finite difference time-domain (FDTD) solutions of Maxwell’s equations. Our HF-WEFS implementation is 2–4 orders of magnitude faster than the FDTD method and enables systematic investigations of the effects of scatterer size and configuration on the focal field. We demonstrate the power of the new HF-WEFS approach by mapping several metrics of focal field distortion as a function of scatterer position. This analysis shows that the maximum focal field distortion occurs for single scatterers placed below the focal plane with an offset from the optical axis. The HF-WEFS method represents an important first step toward the development of a computational model of laser-scanning microscopy of thick cellular/tissue specimens. PMID:25121440

  18. Digital image processing for the rectification of television camera distortions.

    NASA Technical Reports Server (NTRS)

    Rindfleisch, T. C.

    1971-01-01

    All television systems introduce distortions into the imagery they record which influence the results of quantitative photometric and geometric measurements. Digital computer techniques provide a powerful approach to the calibration and rectification of these systematic effects. Nonlinear as well as linear problems can be attacked with flexibility and precision. Methods which have been developed and applied for the removal of structured system noises and the correction of photometric, geometric, and resolution distortions in vidicon systems are briefly described. Examples are given of results derived primarily from the Mariner Mars 1969 television experiment.

  19. Low thermal distortion Extreme-UV lithography reticle and method

    DOEpatents

    Gianoulakis, Steven E.; Ray-Chaudhuri, Avijit K.

    2002-01-01

    Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.

  20. Low thermal distortion extreme-UV lithography reticle

    DOEpatents

    Gianoulakis, Steven E.; Ray-Chaudhuri, Avijit K.

    2001-01-01

    Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.

  1. Low thermal distortion extreme-UV lithography reticle

    DOEpatents

    Gianoulakis, Steven E.; Ray-Chaudhuri, Avijit K.

    2002-01-01

    Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.

  2. Distortion of Crabbed Bunch Due to the Electron Cloud

    SciTech Connect

    Wang, L; Raubenheimer, T.; /SLAC

    2008-05-28

    In order to improve the luminosity, two crab cavities have been installed in KEKB HER and LER [1]. Since there is only one crab cavity in each ring, the crab cavity generates a horizontally titled bunch along the whole ring. The achieved specific luminosity with crabbed bunch is higher, but it is not as high as that from beam-beam simulation [2]. One of the suspicions is the electron cloud. The electron cloud in LER (positron beam) may distort the crabbed bunch and cause the luminosity drop. This note briefly estimates the bunch shape distortion due to the electron cloud in KEKB LER.

  3. Estimation of lens distortion correction from single images

    NASA Astrophysics Data System (ADS)

    Goljan, Miroslav; Fridrich, Jessica

    2014-02-01

    In this paper, we propose a method for estimation of camera lens distortion correction from a single image. Without relying on image EXIF, the method estimates the parameters of the correction by searching for a maximum energy of the so-called linear pattern introduced into the image during image acquisition prior to lens distortion correction. Potential applications of this technology include camera identification using sensor fingerprint, narrowing down the camera model, estimating the distance between the photographer and the subject, forgery detection, and improving the reliability of image steganalysis (detection of hidden data).

  4. Distortion-rotor interaction noise produced by a drooped inlet

    NASA Technical Reports Server (NTRS)

    Smith, E. B.; Moore, M. T.; Gliebe, P. R.

    1980-01-01

    The 'drooped' inlet used on most wing mounted engines produces a wall static pressure distortion at the fan face of about plus or minus 2%. The interaction of the fan rotor with this fixed distortion pattern produces blade passing frequency and harmonic tone levels in flight which contribute to forward radiated engine noise spectra. Data from a wind tunnel test, using both a drooped inlet and an inlet with no droop, show large changes in forward radiated noise levels over a limited fan speed range. An analytical model of this fan noise mechanism is developed and is used to account for the major features of the measured results.

  5. Distortion and Residual Stress Control in Integrally Stiffened Structure Produced by Direct Metal Deposition

    NASA Technical Reports Server (NTRS)

    Lin, Shih-Yung; Hoffman, Eric K.; Domack, Marcia S.

    2007-01-01

    2-D thermo-mechanical model developed to characterize distortion and residual stresses in integral structure produced by DMD. Demonstrated as a tool to guide experimental development of DMD fabrication process for aero structures. Distortion and residual stresses are local to deposit. Most distortion develops during deposition of the first few layers; Little change in distortion or residual stresses after fifth deposit layer Most of distortion is localized just beneath the build. Thicker build plates and the use of build lands results in greatest decrease in levels of distortion. Pre-straining shown to reduce distortion. Difficult to implement, particularly for complex stiffener arrays. Clamp position has complex effect on distortion and stresses. Overall distortion reduced with decreasing clamp clearance. Larger clamp clearances induce bending. Use of pre-heat and active cooling show minor influence on panel distortion. Generate changes in thermal gradients in the build plate.

  6. Electromagnetic Interference Analysis Based on Total Harmonic Distortion Measurement in 900MHz Cordless Telephones

    NASA Astrophysics Data System (ADS)

    Park, Jeung Geun; Kim, Che Young

    In this paper a new electromagnetic (EM) interference analysis is proposed using the total harmonic distortion (THD) measurement of the audio signal by the 900MHz cordless telephones. The cordless telephone network in 900MHz was built up to be weak in EM interference. 400 and 800Hz of the sine-wave signal were used in transmitter (TX) system, and the receiver (RX) system was exposed to the EM interference. The THD value varies as the level of the exposed EM interference changes. The model of the cordless telephone also affects the THD value. By using fluctuation of the THD value depending on the amount of the exposure, the threshold value of the interference electric field strength was derived. Based on the derived threshold value of the electric field strength, validity of the regulation value for low power radio devices by CISPR 22 [CLASS B] and FCC is discussed.

  7. Magnetic soft modes in the distorted triangular antiferromagnet -CaCr2O4

    SciTech Connect

    Toth, Sandor; Lake, Bella; Hradil, Klaudia; Rule, K; Stone, Matthew B; Islam, A. T. M. N.

    2012-01-01

    -CaCr2O4 is a spin-3/2, distorted triangular lattice antiferromagnet with a simple 120 spin structure that masks the complex pattern of exchange interactions. The magnetic excitation spectrum has been measured using inelastic neutron scattering on powder and single crystal samples. It reveals unusual low energy modes which can be explained by linear spin-wave theory assuming nearest and next-nearest neighbor interactions. The mode softening is due to the next-nearest neighbor interactions and indicates a new magnetic phase nearby as revealed by the phase diagram constructed for this system. The extracted direct exchange interactions correlate well with the Cr3+{Cr3+ distances and are in agreement with other chromium oxide delafossite compounds.

  8. Intermodulation distortion measurements of MgB2 thin films grown by HPCVD

    NASA Astrophysics Data System (ADS)

    Cifariello, G.; Aurino, M.; di Gennaro, E.; Lamura, G.; Orgiani, P.; Villegier, J.-C.; Xi, X. X.; Andreone, A.

    2006-06-01

    The two tone intermodulation distortion (IMD) arising in MgB2 thin films synthesized by hybrid physical-chemical vapour deposition (HPCVD) is studied in order to probe the influence of the two bands on the symmetry of the gap function. The measurements are carried out by using a dielectrically loaded copper cavity operating at 7 GHz. Microwave data on samples having critical temperatures above 41 K, very low resistivity values, and residual resistivity ratio larger than 10, are shown. The dependence of the nonlinear surface losses and of the third order intermodulation products on the power feeding the cavity and on the temperature is analyzed. At low power, IMD versus temperature data show the intrinsic s-wave behaviour expected for this compound

  9. Cloaking spin-(1/2) matter waves

    SciTech Connect

    Lin, De-Hone

    2010-06-15

    A physical construct for the cloaking of relativistic spin-(1/2) matter waves is proposed. It is shown that when the effective energy and mass of relativistic spin-(1/2) particles moving in an effective vector field in a spherical shell are controlled, their matter waves can be perfectly guided through the shell without any distortion or loss; that is, the construct provides a three-dimensional cloaking shell for relativistic spin-(1/2) matter waves. The proposal serves as the basis for some interesting applications such as providing a method to guide the matter waves of spin particles and an ideal setup to exhibit spin-spin interactions as well as perfect quantum interferences of some global effects in spin-(1/2) matter waves.

  10. Gravity Waves

    Atmospheric Science Data Center

    2013-04-19

    article title:  Gravity Waves Ripple over Marine Stratocumulus Clouds ... Imaging SpectroRadiometer (MISR), a fingerprint-like gravity wave feature occurs over a deck of marine stratocumulus clouds. Similar ... that occur when a pebble is thrown into a still pond, such "gravity waves" sometimes appear when the relatively stable and stratified air ...

  11. Centration-distortion error: a criterion of perceptual dysfunction.

    PubMed

    Mecke, V

    This was a study to determine whether centration, as a perceptual process, could be a criterion for differentiating between neurologically impaired and emotionally disturbed children. Centration was defined by Piaget as a prolonged involuntary attachment of a sensory modality to one part of a field, causing perceptual errors of exaggerations and distortions. It is hypothesized that centration would affect motor behavior, producing effects on drawing tasks characterized by separation of designs or their parts, coincident with distortions of the figures drawn. The neurologically impaired children were identified as having primary difficulties with perception whereas the emotionally disturbed children would have primary difficulties with intellection. The centration-distortion error would characterize the drawing of the neurologically impaired but not those of the emotionally disturbed children. A sample of 44 children was selected, each with EEG records, psychological tests and psychiatric interviews used as differential criteria for the groups. Eleven children were diagnosed as having minimal brain damage, 33 as emotionally disturbed. Three psychologists scored the Bender Gestalt tests, blind, for indicators of brain injury and emotional disturbance as defined by Koppitz' criteria, and for the centration-distortion error. The hypothesis was upheld at the .001 level of confidence, validating an earlier pilot study. PMID:4468761

  12. Face distortion aftereffects in personally familiar, famous, and unfamiliar faces.

    PubMed

    Walton, Billy Ronald Peter; Hills, Peter James

    2012-01-01

    The internal face prototype is thought to be a construction of the average of every previously viewed face (Schwaninger et al., 2003). However, the influence of the most frequently encountered faces (i.e., personally familiar faces) has been generally understated. The current research explored the face distortion aftereffect in unfamiliar, famous, and personally familiar (each subject's parent) faces. Forty-eight adult participants reported whether faces were distorted or not (distorted by shifting the eyes in the vertical axis) of a series of images that included unfamiliar, famous, and personally familiar faces. The number of faces perceived to be "odd" was measured pre- and post-adaptation to the most extreme distortion. Participants were adapted to either an unfamiliar, famous, or personally familiar face. The results indicate that adaptation transferred from unfamiliar faces to personally familiar faces more so than the converse and aftereffects did not transfer from famous faces to unfamiliar faces. These results are indicative of representation differences between unfamiliar, famous, and personally familiar faces, whereby personally familiar faces share representations of both unfamiliar and famous faces.

  13. Information Distortion in the Evaluation of a Single Option

    ERIC Educational Resources Information Center

    Bond, Samuel D.; Carlson, Kurt A.; Meloy, Margaret G.; Russo, J. Edward; Tanner, Robin J.

    2007-01-01

    Extending previous work on biased predecisional processing, we investigate the distortion of information during the evaluation of a single option. A coherence-based account of the evaluation task suggests that individuals will form an initial assessment of favorability toward the option and then bias their evaluation of subsequent information to…

  14. Pathophysiological Distortions in Time Perception and Timed Performance

    ERIC Educational Resources Information Center

    Allman, Melissa J.; Meck, Warren H.

    2012-01-01

    Distortions in time perception and timed performance are presented by a number of different neurological and psychiatric conditions (e.g. Parkinson's disease, schizophrenia, attention deficit hyperactivity disorder and autism). As a consequence, the primary focus of this review is on factors that define or produce systematic changes in the…

  15. Body Dysmorphic Disorder: Easing the Distress of Distortion.

    ERIC Educational Resources Information Center

    Fore, Cynthia M.

    People who suffer from body dysmorphic disorder believe that their body is defected and that this defect makes them ugly. Their distorted body image can be precipitated by many internal and external factors and as a result of their imagined defect, these normal-appearing individuals exhibit self-defeating behaviors. The disorder can lead to the…

  16. Correction of the distortion in frequency modulation spectroscopy

    NASA Astrophysics Data System (ADS)

    du Burck, F.; Lopez, O.

    2004-07-01

    A theoretical expression for the detected signal in frequency modulation spectroscopy with a residual amplitude modulation (RAM) is computed. The line shape distortion induced by the RAM is shown to be essentially suppressed for a proper choice of the modulation and detection parameters. The experimental tests are carried out in saturation spectroscopy of I2 at 514.5 nm. Experimental limitations are analysed.

  17. The influence of gain nonlinearities on distortion in semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Lysak, Vladimir V.; Schatz, Richard; Shulika, Aleksey V.; Sukhoivanov, Igor A.; Kjebon, O.

    2004-09-01

    The semiconductor laser is commonly used as a light source in fiber-optical telecommunication systems. In order to send as much information as possible in a short time, it is important that the laser has a large modulation bandwidth, i.e., the turn-on and turn-off time should be as short as possible. In analogue fiber optic systems for transmission of radio or television signals, it is also important that the light from the laser increases linearly with driving current even at high modulation frequencies. Otherwise, the transmitted signal will become distorted. The modulation bandwidth and the modulation distortion are dependent both on the laser structure and the gain characteristics of the active material. One of the most useful approaches for the time-domain description of the response of optoelectronic devices is the so-called "rate equation model," which has been widely used to describe laser performance. Commonly, laser models with simple gain expressions are used for simulation of laser dynamics. In these models the small-signal dynamic parameters like the differential gain and gain saturation parameter are extracted from modulation response measurements. However, we show that in order to correctly calculate distortion, an accurate model of the dependence of gain on carrier density, n, and photon density, s, is needed. Commonly used gain models, fitted to give exactly the same modulation response can give significantly different distortion behavior.

  18. An Accurate Projector Calibration Method Based on Polynomial Distortion Representation

    PubMed Central

    Liu, Miao; Sun, Changku; Huang, Shujun; Zhang, Zonghua

    2015-01-01

    In structure light measurement systems or 3D printing systems, the errors caused by optical distortion of a digital projector always affect the precision performance and cannot be ignored. Existing methods to calibrate the projection distortion rely on calibration plate and photogrammetry, so the calibration performance is largely affected by the quality of the plate and the imaging system. This paper proposes a new projector calibration approach that makes use of photodiodes to directly detect the light emitted from a digital projector. By analyzing the output sequence of the photoelectric module, the pixel coordinates can be accurately obtained by the curve fitting method. A polynomial distortion representation is employed to reduce the residuals of the traditional distortion representation model. Experimental results and performance evaluation show that the proposed calibration method is able to avoid most of the disadvantages in traditional methods and achieves a higher accuracy. This proposed method is also practically applicable to evaluate the geometric optical performance of other optical projection system. PMID:26492247

  19. CMB all-scale blackbody distortions induced by linearizing temperature

    NASA Astrophysics Data System (ADS)

    Notari, Alessio; Quartin, Miguel

    2016-08-01

    Cosmic microwave background (CMB) experiments, such as WMAP and Planck, measure intensity anisotropies and build maps using a linearized formula for relating them to the temperature blackbody fluctuations. However, this procedure also generates a signal in the maps in the form of y -type distortions which is degenerate with the thermal Sunyaev Zel'dovich (tSZ) effect. These are small effects that arise at second order in the temperature fluctuations not from primordial physics but from such a limitation of the map-making procedure. They constitute a contaminant for measurements of our peculiar velocity, the tSZ and primordial y -distortions. They can nevertheless be well modeled and accounted for. We show that the distortions arise from a leakage of the CMB dipole into the y -channel which couples to all multipoles, mostly affecting the range ℓ≲400 . This should be visible in Planck's y -maps with an estimated signal-to-noise ratio of about 12. We note however that such frequency-dependent terms carry no new information on the nature of the CMB dipole. This implies that the real significance of Planck's Doppler coupling measurements is actually lower than reported by the collaboration. Finally, we quantify the level of contamination in tSZ and primordial y -type distortions and show that it is above the sensitivity of proposed next-generation CMB experiments.

  20. Depression and Distortion in the Attribution of Causality

    ERIC Educational Resources Information Center

    Rizley, Ross

    1978-01-01

    Two cognitive models of depression have attracted considerable attention recently: Seligman's (1975) learned helplessness model and Beck's (1967) cognitive schema approach. Describes each model and, in two studies, evaluates the assumption that depression is associated with systematic distortion in cognition regarding causal and controlling…

  1. 3D magnetotelluric inversion with full distortion matrix

    NASA Astrophysics Data System (ADS)

    Gribenko, A. V.; Zhdanov, M. S.

    2014-12-01

    Distortion of regional electric fields by local structures represent one of the major problems facing three-dimensional magnetotelluric (MT) interpretation. Effect of 3D local inhomogenities on MT data can be described by a real 2x2 distortion matrix. In this project we develop a method of simultaneous inversion of the full MT impedance data for 3D conductivity distribution and for the distortion matrix. Tikhonov regularization is employed to solve the resulting inverse problem. Integral equations method is used to compute MT responses. Minimization of the cost functional is achieved via conjugate gradient method. The inversion algorithm is tested on the synthetic data from Dublin Secret Model II (DSM 2) for which multiple inversion solutions are available for comparison. Inclusion of the distortion matrix provides faster convergence and allows coarser discretization of the near-surface while achievingsimilar or better data fits as inversion for the conductivity only with finely discretized shallow regions. As a field data example we chose a subset of the EarthScope MT dataset covering Great Basin and adjacent areas of the Western United States. Great Basin data inversion identified several prominent conductive zones which correlate well with areas of tectonic and geothermal activity.

  2. 'Distorteidolias' - fantastic perceptive distortion. A new, pure dorsomedial thalamic syndrome.

    PubMed

    Delgado, Montserrat G; Bogousslavsky, Julien

    2013-01-01

    The role of the thalamus in the pathogenesis of the visual and auditory hallucinations has been reported under the name of peduncular hallucinosis, usually with coexisting midbrain involvement. These hallucinations typically take the form of dreamy de novo productions (phanteidolias), less often that of transformations of perceptions into new items (such as seeing faces in clouds) called pareidolias. However, hallucinations taking the form of a complex distortion of perception is a different phenomenon, which to our knowledge has not been reported. We studied 2 patients with complex, 'fantastic', perceptive distortion involving the visual and auditory systems after thalamic stroke limited to the region of the dorsomedial nucleus, sparing the intralaminar nuclei and the midbrain (explaining the lack of disorders of consciousness and confusional state). Our patients reported the modification of usual stimuli (face, body, voices) into unreal, fantastically distorted perceptions (monstrous change of shapes or sounds without appearance of new items). While the exact mechanism leading to such perceptive distortions remains unknown, a release phenomenon due to damage to the dorsomedial thalamus (probably affecting cholinergic system) responsible for a disinhibition of cortical function involved in familiarity of perception seems likely. We suggest that these hallucinations should be called 'distorteidolias'.

  3. Computer Software for Displaying Map Projections and Comparing Distortions.

    ERIC Educational Resources Information Center

    Wikle, Thomas

    1991-01-01

    Discusses software that educators can use to teach about distortions associated with alternative map projections. Examines the Projection, MicroCAM, World, and Atlas-GIS software programs. Suggests using the software in either introductory or more advanced courses dealing with map design or thematic cartography. Explains how to obtain the…

  4. Improving MRI surface coil decoupling to reduce B1 distortion

    NASA Astrophysics Data System (ADS)

    Larson, Christian

    As clinical MRI systems continue to advance, larger focus is being given to image uniformity. Good image uniformity begins with generating uniform magnetic fields, which are easily distorted by induced currents on receive-only surface coils. It has become an industry standard to combat these induced currents by placing RF blocking networks on surface coils. This paper explores the effect of blocking network impedance of phased array surface coils on B1 distortion. It has been found and verified, that traditional approaches for blocking network design in complex phased arrays can leave undesirable B1 distortions at 3 Tesla. The traditional approach of LC tank blocking is explored, but shifts from the idea that higher impedance equals better B1 distortion at 3T. The result is a new design principle for a tank with a finite inductive reactance at the Larmor Frequency. The solution is demonstrated via simulation using a simple, single, large tuning loop. The same loop, along with a smaller loop, is used to derive the new design principle, which is then applied to a complex phased array structure.

  5. A Numerical Investigation on Configurational Distortions in Nematic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Pandolfi, Anna; Napoli, Gaetano

    2011-10-01

    When subjected to magnetic or electric fields, nematic liquid crystals confined between two parallel glass plates and initially uniformly oriented may undergo homogeneous one-dimensional spatial distortions (Fréedericksz and Zolina, Trans. Faraday Soc. 29:919, 1933) or periodic distortions (Lonberg and Meyer, Phys. Rev. Lett. 55(7):718-721, 1985; and Srajer et al., Phys. Rev. Lett. 67(9):1102-1105, 1991). According to the experimental observations, periodic phases are stable configurations at intermediate intensity of the acting field, while homogeneous phases are stable at higher strengths. We present a fully nonlinear finite element approach able to describe homogeneous and periodic configurational phases in a cell of confined nematic liquid crystal with strong planar anchoring boundary conditions. Stationary configurations are obtained by setting to zero the first variation of the discretized total energy of the system. Unstable configurations are identified by evaluating the behavior of the solution under small numerical perturbations. Numerical calculations are able to describe the evolution of the configurational distortions as a function of the applied field and are able to capture the critical points between homogeneous and periodic phases. The proposed approach has been proved to be an excellent tool to predict the existence of unstable or metastable distortions, characterized by higher energy levels.

  6. System for interferometric distortion measurements that define an optical path

    DOEpatents

    Bokor, Jeffrey; Naulleau, Patrick

    2003-05-06

    An improved phase-shifting point diffraction interferometer can measure both distortion and wavefront aberration. In the preferred embodiment, the interferometer employs an object-plane pinhole array comprising a plurality of object pinholes located between the test optic and the source of electromagnetic radiation and an image-plane mask array that is positioned in the image plane of the test optic. The image-plane mask array comprises a plurality of test windows and corresponding reference pinholes, wherein the positions of the plurality of pinholes in the object-plane pinhole array register with those of the plurality of test windows in image-plane mask array. Electromagnetic radiation that is directed into a first pinhole of object-plane pinhole array thereby creating a first corresponding test beam image on the image-plane mask array. Where distortion is relatively small, it can be directly measured interferometrically by measuring the separation distance between and the orientation of the test beam and reference-beam pinhole and repeating this process for at least one other pinhole of the plurality of pinholes of the object-plane pinhole array. Where the distortion is relative large, it can be measured by using interferometry to direct the stage motion, of a stage supporting the image-plane mask array, and then use the final stage motion as a measure of the distortion.

  7. Hierarchical Clustering and the Concept of Space Distortion.

    ERIC Educational Resources Information Center

    Hubert, Lawrence; Schultz, James

    An empirical assesssment of the space distortion properties of two prototypic hierarchical clustering procedures is given in terms of an occupancy model developed from combinatorics. Using one simple example, the single-link and complete-link clustering strategies now in common use in the behavioral sciences are empirically shown to be space…

  8. Low-distortion receiver for bilevel, baseband PCM waveforms

    NASA Technical Reports Server (NTRS)

    Proch, G. E.

    1974-01-01

    Digital receiver improves discrimination between information signals and noise and provides order to magnitude reduction in systematic distortion. Receiver combines advantages of band-limiting prefilter and high-amplitude thresholds to provide asynchronous discrimination between information signals and spurious signals.

  9. Statistical Research for Probabilistic Model of Distortions of Remote Sensing

    NASA Astrophysics Data System (ADS)

    Ayman, Iskakova

    2016-08-01

    In this work the new multivariate discrete probability model of distribution of processes distortion of radiation from remote sensing data is proposed and studied. Research was performed on a full cycle adopted in mathematical statistics, namely, the model was constructed and investigated, various methods for estimating the parameters was proposed and test the hypothesis that the model adequacy observations, was considered.

  10. Tidal Distortion and Disruption of Earth-Crossing Asteriods

    NASA Technical Reports Server (NTRS)

    Love, Stanley G.; Bottke, William, Jr.

    1997-01-01

    We represent results of numerical simulations that show Earth's tidal forces can both distort and disrupt Earth-crossing asteriods (ECAs) that have weak rubble-pile structures. Building on previous studies, we consider more realistic asteriod shapes and trajectories, test a variety of spin and rates and axis orientations, and employ a dissipation algorithm to more accurately treat collisions between particles.

  11. Notes on Distortions in the Market for Educational Services.

    ERIC Educational Resources Information Center

    Olson, Lawrence S.

    The document analyzes economic factors that might cause the output of educational services to diverge from the theoretical optimum because of a divergence between marginal social valuation and marginal social cost. Education contains both investment and consumption aspects. The analysis shows that the only distortion resulting from uncertainty…

  12. Magnetism and structural distortions in uranium sulfide under pressure

    NASA Astrophysics Data System (ADS)

    Jeffries, J. R.; Söderlind, P.; Cynn, H.; Landa, A.; Evans, W. J.; Weir, S. T.; Vohra, Y. K.; Lander, G. H.

    2013-06-01

    Uranium sulfide belongs to a class of uranium monochalcogenides that crystallize in the rocksalt structure and exhibit ferromagnetism at low temperature. The magnetism is believed to play a role in the low-temperature rhombohedral distortion, possibly due to its large magnetic anisotropy. We have performed electrical and structural characterization along with density-functional theory calculations as functions of pressure to help understand the interplay between structure and magnetism in US. Theoretical calculations suggest that ferromagnetic order is responsible for the small distortion at ambient pressure and low temperature. Under pressure, the Curie temperature is reduced monotonically until it discontinuously disappears near a pressure-induced deformation of the crystal structure. This high-pressure distortion is identical to the one correlated with the onset of magnetic order, but with a larger change in the cell angle. Calculations imply a reduction in the electronic band energy as the driving force for the pressure-induced structure, but the loss of magnetic order associated with this distortion remains a mystery. The high-pressure electronic phase diagram may shed light on the magnetostructural free energy landscape of US.

  13. Distortion of binoculars revisited: does the sweet spot exist?

    PubMed

    Merlitz, Holger

    2010-01-01

    Sixty years ago, August Sonnefeld of Zeiss reported on observations with experimental telescopes. The goal of his investigation was to determine the ideal amount of distortion applied to optical instruments that are used in combination with the human eye. His studies were inconclusive and partially contradictory. We have picked up this problem once again, adopting a modern point of view about the human imaging process, and supported by computer graphics. Based on experiments with Helmholtz checkerboards, we argue that human imaging introduces a certain amount of barrel distortion, which has to be counterbalanced through the implementation of an equally strong pincushion distortion into the binocular design. We discuss in detail how this approach is capable of eliminating the globe effect of the panning binocular and how the residual pincushion distortion affects the image when the eye is pointing off-center. Our results support the binocular designer in optimizing his instrument for its intended mode of application, and may help binocular users and astronomers better understand their tools. PMID:20035302

  14. Centration-distortion error: a criterion of perceptual dysfunction.

    PubMed

    Mecke, V

    This was a study to determine whether centration, as a perceptual process, could be a criterion for differentiating between neurologically impaired and emotionally disturbed children. Centration was defined by Piaget as a prolonged involuntary attachment of a sensory modality to one part of a field, causing perceptual errors of exaggerations and distortions. It is hypothesized that centration would affect motor behavior, producing effects on drawing tasks characterized by separation of designs or their parts, coincident with distortions of the figures drawn. The neurologically impaired children were identified as having primary difficulties with perception whereas the emotionally disturbed children would have primary difficulties with intellection. The centration-distortion error would characterize the drawing of the neurologically impaired but not those of the emotionally disturbed children. A sample of 44 children was selected, each with EEG records, psychological tests and psychiatric interviews used as differential criteria for the groups. Eleven children were diagnosed as having minimal brain damage, 33 as emotionally disturbed. Three psychologists scored the Bender Gestalt tests, blind, for indicators of brain injury and emotional disturbance as defined by Koppitz' criteria, and for the centration-distortion error. The hypothesis was upheld at the .001 level of confidence, validating an earlier pilot study.

  15. Age Differences in Dreams. II: Distortion and Other Variables.

    ERIC Educational Resources Information Center

    Zepelin, Harold

    1981-01-01

    Age-related change in manifest dream content was assessed in dreams recalled from REM sleep by (N=58) men aged (27-64), and in dreams recalled from sleep at home. Evidence indicated a small age-related decline in dream distortion and family-related content. (Author)

  16. Simulation on the Measurement Method of Geometric Distortion of Telescopes

    NASA Astrophysics Data System (ADS)

    Fan, Li; Shu-lin, Ren

    2016-07-01

    The accurate measurement on the effect of telescope geometric distortion is conducive to improving the astrometric positioning accuracy of telescopes, which is of significant importance for many disciplines of astronomy, such as stellar clusters, natural satellites, asteroids, comets, and other celestial bodies in the solar system. For this reason, the predecessors have developed an iterative self-calibration method to measure the telescope geometric distortion by dithering observations in a dense star field, and achieved fine results. However, the previous work did not make constraints on the density of star field, and the dithering mode, but chose empirically some good conditions (for example, a denser star field and a larger dithering number) to observe, which took up much observing time, and caused a rather low efficiency. In order to explore the validity of the self-calibration method, and optimize its observational conditions, it is necessary to carry out the corresponding simulations. In this paper, we introduce first the self-calibration method in detail, then by the simulation method, we verify the effectiveness of the self-calibration method, and make further optimizations on the observational conditions, such as the density of star field and the dithering number, to achieve a higher accuracy of geometric distortion measurement. Finally, taking consideration of the practical application for correcting the geometric distortion effect, we have analyzed the relationship between the number of reference stars in the field of view and the astrometric accuracy by virtue of the simulation method.

  17. Spontaneous perceptual facial distortions correlate with ventral occipitotemporal activity.

    PubMed

    Dalrymple, Kirsten A; Davies-Thompson, Jodie; Oruc, Ipek; Handy, Todd C; Barton, Jason J S; Duchaine, Brad

    2014-07-01

    Prosopometamorphopsia is a disorder of face perception in which faces appear distorted to the perceiver. The neural basis of prosopometamorphopsia is unclear, but may involve abnormal activity in face-selective areas in the ventral occipito-temporal pathway. Here we present the case of AS, a 44-year-old woman who reports persistent perceptual distortions of faces with no known cause. AS was presented with facial images and rated the magnitude of her distortions while activity in her core face areas and other areas in the ventral visual pathway was measured using functional magnetic resonance imaging. The magnitude of her distortions was positively correlated with signal changes in the right occipital face area (OFA) and right fusiform face area (FFA), as well as right V1-V3, and right lateral occipital cortex (LOC). There was also a trend for a significant correlation with signal in the left OFA and right inferior frontal gyrus (IFG), but not in the right or left superior temporal sulcus (STS). These results suggest that AS' prosopometamorphopsia reflects anomalous activity in face-processing network, particularly in the ventral occipitotemporal cortex.

  18. Turkish Version of the Cognitive Distortions Questionnaire: Psychometric Properties.

    PubMed

    Batmaz, Sedat; Kocbiyik, Sibel; Yuncu, Ozgur Ahmet

    2015-01-01

    Cognitive distortions are interrelated with all layers of cognitions, and they may be part of the treatment once they are accessed, identified, labeled, and changed. From both a research and a clinical perspective, it is of utmost importance to disentangle cognitive distortions from similar constructs. Recently, the Cognitive Distortions Questionnaire (CD-Quest), a brief and comprehensive measure, was developed to assess both the frequency and the intensity of cognitive distortions. The aim of the present study was to assess the psychometric properties of the Turkish version of the CD-Quest in a psychiatric outpatient sample. Demographic and clinical data of the participants were analyzed by descriptive statistics. For group comparisons, Student's t-test was applied. An exploratory principal components factor analysis was performed, followed by an oblique rotation. To assess the internal consistency of the scale Cronbach's α was computed. The correlation coefficient was calculated for test-retest reliability over a 4-week period. For concurrent validity, bivariate Pearson correlation analyses were conducted with the measures of mood severity and negatively biased cognitions. The results revealed that the scale had excellent internal consistency, good test-retest reliability, unidimensional factor structure, and evidence of concurrent and discriminant validity.

  19. A metasurface carpet cloak for electromagnetic, acoustic and water waves.

    PubMed

    Yang, Yihao; Wang, Huaping; Yu, Faxin; Xu, Zhiwei; Chen, Hongsheng

    2016-01-29

    We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the reflection waves as if the incident waves impinge onto a flat mirror. The finite element simulation results demonstrate that an object can be hidden under these three kinds of waves with a single metasurface cloak.

  20. A metasurface carpet cloak for electromagnetic, acoustic and water waves

    PubMed Central

    Yang, Yihao; Wang, Huaping; Yu, Faxin; Xu, Zhiwei; Chen, Hongsheng

    2016-01-01

    We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the reflection waves as if the incident waves impinge onto a flat mirror. The finite element simulation results demonstrate that an object can be hidden under these three kinds of waves with a single metasurface cloak. PMID:26822429

  1. A metasurface carpet cloak for electromagnetic, acoustic and water waves

    NASA Astrophysics Data System (ADS)

    Yang, Yihao; Wang, Huaping; Yu, Faxin; Xu, Zhiwei; Chen, Hongsheng

    2016-01-01

    We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the reflection waves as if the incident waves impinge onto a flat mirror. The finite element simulation results demonstrate that an object can be hidden under these three kinds of waves with a single metasurface cloak.

  2. A metasurface carpet cloak for electromagnetic, acoustic and water waves.

    PubMed

    Yang, Yihao; Wang, Huaping; Yu, Faxin; Xu, Zhiwei; Chen, Hongsheng

    2016-01-01

    We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the reflection waves as if the incident waves impinge onto a flat mirror. The finite element simulation results demonstrate that an object can be hidden under these three kinds of waves with a single metasurface cloak. PMID:26822429

  3. Dynamic wake distortion model for helicopter maneuvering flight

    NASA Astrophysics Data System (ADS)

    Zhao, Jinggen

    A new rotor dynamic wake distortion model, which can be used to account for the rotor transient wake distortion effect on inflow across the rotor disk during helicopter maneuvering and transitional flight in both hover and forward flight conditions, is developed. The dynamic growths of the induced inflow perturbation across rotor disk during different transient maneuvers, such as a step pitch or roll rate, a step climb rate and a step change of advance ratio are investigated by using a dynamic vortex tube analysis. Based on the vortex tube results, a rotor dynamic wake distortion model, which is expressed in terms of a set of ordinary differential equations, with rotor longitudinal and lateral wake curvatures, wake skew and wake spacing as states, is developed. Also, both the Pitt-Peters dynamic inflow model and the Peters-He finite state inflow model for axial or forward flight are augmented to account for rotor dynamic wake distortion effect during helicopter maneuvering flight. To model the aerodynamic interaction among main rotor, tail rotor and empennage caused by rotor wake curvature effect during helicopter maneuvering flight, a reduced order model based on a vortex tube analysis is developed. Both the augmented Pitt-Peters dynamic inflow model and the augmented Peters-He finite state inflow model, combined with the developed dynamic wake distortion model, together with the interaction model are implemented in a generic helicopter simulation program of UH-60 Black Hawk helicopter and the simulated vehicle control responses in both time domain and frequency domain are compared with flight test data of a UH-60 Black Hawk helicopter in both hover and low speed forward flight conditions.

  4. Quantification of structural distortions in the transmembrane helices of GPCRs.

    PubMed

    Deupi, Xavier

    2012-01-01

    A substantial part of the structural and much of the functional information about G protein-coupled receptors (GPCRs) comes from studies on rhodopsin. Thus, analysis tools for detailed structure comparison are key to see to what extent this information can be extended to other GPCRs. Among the methods to evaluate protein structures and, in particular, helix distortions, HELANAL has the advantage that it provides data (local bend and twist angles) that can be easily translated to structural effects, as a local opening/tightening of the helix.In this work I show how HELANAL can be used to extract detailed structural information of the transmembrane bundle of GPCRs, and I provide some examples on how these data can be interpreted to study basic principles of protein structure, to compare homologous proteins and to study mechanisms of receptor activation. Also, I show how in combination with the sequence analysis tools provided by the program GMoS, distortions in individual receptors can be put in the context of the whole Class A GPCR family. Specifically, quantification of the strong proline-induced distortions in the transmembrane bundle of rhodopsin shows that they are not standard proline kinks. Moreover, the helix distortions in transmembrane helix (TMH) 5 and TMH 6 of rhodopsin are also present in the rest of GPCR crystal structures obtained so far, and thus, rhodopsin-based homology models have modeled correctly these strongly distorted helices. While in some cases the inherent "rhodopsin bias" of many of the GPCR models to date has not been a disadvantage, the availability of more templates will clearly result in better homology models. This type of analysis can be, of course, applied to any protein, and it may be particularly useful for the structural analysis of other membrane proteins. A detailed knowledge of the local structural changes related to ligand binding and how they are translated into larger-scale movements of transmembrane domains is key to

  5. The Selfish Segregation Distorter Gene Complex of Drosophila melanogaster

    PubMed Central

    Larracuente, Amanda M.; Presgraves, Daven C.

    2012-01-01

    Segregation Distorter (SD) is an autosomal meiotic drive gene complex found worldwide in natural populations of Drosophila melanogaster. During spermatogenesis, SD induces dysfunction of SD+ spermatids so that SD/SD+ males sire almost exclusively SD-bearing progeny rather than the expected 1:1 Mendelian ratio. SD is thus evolutionarily “selfish,” enhancing its own transmission at the expense of its bearers. Here we review the molecular and evolutionary genetics of SD. Genetic analyses show that the SD is a multilocus gene complex involving two key loci—the driver, Segregation distorter (Sd), and the target of drive, Responder (Rsp)—and at least three upward modifiers of distortion. Molecular analyses show that Sd encodes a truncated duplication of the gene RanGAP, whereas Rsp is a large pericentromeric block of satellite DNA. The Sd–RanGAP protein is enzymatically wild type but mislocalized within cells and, for reasons that remain unclear, appears to disrupt the histone-to-protamine transition in drive-sensitive spermatids bearing many Rsp satellite repeats but not drive-insensitive spermatids bearing few or no Rsp satellite repeats. Evolutionary analyses show that the Sd–RanGAP duplication arose recently within the D. melanogaster lineage, exploiting the preexisting and considerably older Rsp satellite locus. Once established, the SD haplotype collected enhancers of distortion and suppressors of recombination. Further dissection of the molecular genetic and cellular basis of SD-mediated distortion seems likely to provide insights into several important areas currently understudied, including the genetic control of spermatogenesis, the maintenance and evolution of satellite DNAs, the possible roles of small interfering RNAs in the germline, and the molecular population genetics of the interaction of genetic linkage and natural selection. PMID:22964836

  6. The selfish Segregation Distorter gene complex of Drosophila melanogaster.

    PubMed

    Larracuente, Amanda M; Presgraves, Daven C

    2012-09-01

    Segregation Distorter (SD) is an autosomal meiotic drive gene complex found worldwide in natural populations of Drosophila melanogaster. During spermatogenesis, SD induces dysfunction of SD(+) spermatids so that SD/SD(+) males sire almost exclusively SD-bearing progeny rather than the expected 1:1 Mendelian ratio. SD is thus evolutionarily "selfish," enhancing its own transmission at the expense of its bearers. Here we review the molecular and evolutionary genetics of SD. Genetic analyses show that the SD is a multilocus gene complex involving two key loci--the driver, Segregation distorter (Sd), and the target of drive, Responder (Rsp)--and at least three upward modifiers of distortion. Molecular analyses show that Sd encodes a truncated duplication of the gene RanGAP, whereas Rsp is a large pericentromeric block of satellite DNA. The Sd-RanGAP protein is enzymatically wild type but mislocalized within cells and, for reasons that remain unclear, appears to disrupt the histone-to-protamine transition in drive-sensitive spermatids bearing many Rsp satellite repeats but not drive-insensitive spermatids bearing few or no Rsp satellite repeats. Evolutionary analyses show that the Sd-RanGAP duplication arose recently within the D. melanogaster lineage, exploiting the preexisting and considerably older Rsp satellite locus. Once established, the SD haplotype collected enhancers of distortion and suppressors of recombination. Further dissection of the molecular genetic and cellular basis of SD-mediated distortion seems likely to provide insights into several important areas currently understudied, including the genetic control of spermatogenesis, the maintenance and evolution of satellite DNAs, the possible roles of small interfering RNAs in the germline, and the molecular population genetics of the interaction of genetic linkage and natural selection.

  7. Accurate Orientation Estimation Using AHRS under Conditions of Magnetic Distortion

    PubMed Central

    Yadav, Nagesh; Bleakley, Chris

    2014-01-01

    Low cost, compact attitude heading reference systems (AHRS) are now being used to track human body movements in indoor environments by estimation of the 3D orientation of body segments. In many of these systems, heading estimation is achieved by monitoring the strength of the Earth's magnetic field. However, the Earth's magnetic field can be locally distorted due to the proximity of ferrous and/or magnetic objects. Herein, we propose a novel method for accurate 3D orientation estimation using an AHRS, comprised of an accelerometer, gyroscope and magnetometer, under conditions of magnetic field distortion. The system performs online detection and compensation for magnetic disturbances, due to, for example, the presence of ferrous objects. The magnetic distortions are detected by exploiting variations in magnetic dip angle, relative to the gravity vector, and in magnetic strength. We investigate and show the advantages of using both magnetic strength and magnetic dip angle for detecting the presence of magnetic distortions. The correction method is based on a particle filter, which performs the correction using an adaptive cost function and by adapting the variance during particle resampling, so as to place more emphasis on the results of dead reckoning of the gyroscope measurements and less on the magnetometer readings. The proposed method was tested in an indoor environment in the presence of various magnetic distortions and under various accelerations (up to 3 g). In the experiments, the proposed algorithm achieves <2° static peak-to-peak error and <5° dynamic peak-to-peak error, significantly outperforming previous methods. PMID:25347584

  8. Broadband distortion modeling in Lyman-α forest BAO fitting

    NASA Astrophysics Data System (ADS)

    Blomqvist, Michael; Kirkby, David; Bautista, Julian E.; Arinyo-i-Prats, Andreu; Busca, Nicolás G.; Miralda-Escudé, Jordi; Slosar, Anže; Font-Ribera, Andreu; Margala, Daniel; Schneider, Donald P.; Vazquez, Jose A.

    2015-11-01

    In recent years, the Lyman-α absorption observed in the spectra of high-redshift quasars has been used as a tracer of large-scale structure by means of the three-dimensional Lyman-α forest auto-correlation function at redshift zsimeq 2.3, but the need to fit the quasar continuum in every absorption spectrum introduces a broadband distortion that is difficult to correct and causes a systematic error for measuring any broadband properties. We describe a k-space model for this broadband distortion based on a multiplicative correction to the power spectrum of the transmitted flux fraction that suppresses power on scales corresponding to the typical length of a Lyman-α forest spectrum. Implementing the distortion model in fits for the baryon acoustic oscillation (BAO) peak position in the Lyman-α forest auto-correlation, we find that the fitting method recovers the input values of the linear bias parameter bF and the redshift-space distortion parameter βF for mock data sets with a systematic error of less than 0.5%. Applied to the auto-correlation measured for BOSS Data Release 11, our method improves on the previous treatment of broadband distortions in BAO fitting by providing a better fit to the data using fewer parameters and reducing the statistical errors on βF and the combination bF(1+βF) by more than a factor of seven. The measured values at redshift z=2.3 are βF=1.39+0.11 +0.24 +0.38-0.10 -0.19 -0.28 and bF(1+βF)=-0.374+0.007 +0.013 +0.020-0.007 -0.014 -0.022 (1σ, 2σ and 3σ statistical errors). Our fitting software and the input files needed to reproduce our main results are publicly available.

  9. Another look at distortions of the Cosmic Microwave Background spectrum

    NASA Astrophysics Data System (ADS)

    De Zotti, G.; Negrello, M.; Castex, G.; Lapi, A.; Bonato, M.

    2016-03-01

    We review aspects of Cosmic Microwave Background (CMB) spectral distortions which do not appear to have been fully explored in the literature. In particular, implications of recent evidences of heating of the intergalactic medium (IGM) by feedback from active galactic nuclei are investigated. Taking also into account the IGM heating associated to structure formation, we argue that values of the y parameter of several × 10-6, i.e. a factor of a few below the COBE/FIRAS upper limit, are to be expected. The Compton scattering by the re-ionized plasma also re-processes primordial distortions, adding a y-type contribution. Hence no pure Bose-Einstein-like distortions are to be expected. An assessment of Galactic and extragalactic foregrounds, taking into account the latest results from the Planck satellite as well as the contributions from the strong CII and CO lines from star-forming galaxies, demonstrates that a foreground subtraction accurate enough to fully exploit the PIXIE sensitivity will be extremely challenging. Motivated by this fact we also discuss methods to detect spectral distortions not requiring absolute measurements and show that accurate determinations of the frequency spectrum of the CMB dipole amplitude may substantially improve over COBE/FIRAS limits on distortion parameters. Such improvements may be at reach of next generation CMB anisotropy experiments. The estimated amplitude of the Cosmic Infrared Background (CIB) dipole might be detectable by careful analyses of Planck maps at the highest frequencies. Thus Planck might provide interesting constraints on the CIB intensity, currently known with a simeq 30% uncertainty.

  10. A mesoscale gravity wave event observed during CCOPE. II - Interactions between mesoscale convective systems and the antecedent waves. [Cooperative Convection Precipitation Experiment

    NASA Technical Reports Server (NTRS)

    Koch, Steven E.; Golus, Robert E.; Dorian, Paul B.

    1988-01-01

    The interactions between preexisting gravity waves and convective systems were investigated using data obtained by the Cooperative Convection Precipitation Experiment observational network in Montana on July 11-12, 1981. The results indicate that strong convection substantially affects gravity waves locally by augmenting the wave amplitude, reducing its wavelength, distorting the wave shape, altering the wave phase velocity, and greatly weakening the in-phase covariance between the perturbation wind and pressure fields. These convective effects upon gravity waves are explained in terms of hydrostatic and nonhydrostatic pressure forces and gust front processes associated with thunderstorms.

  11. Regional bit allocation and rate distortion optimization for multiview depth video coding with view synthesis distortion model.

    PubMed

    Zhang, Yun; Kwong, Sam; Xu, Long; Hu, Sudeng; Jiang, Gangyi; Kuo, C-C Jay

    2013-09-01

    In this paper, we propose a view synthesis distortion model (VSDM) that establishes the relationship between depth distortion and view synthesis distortion for the regions with different characteristics: color texture area corresponding depth (CTAD) region and color smooth area corresponding depth (CSAD), respectively. With this VSDM, we propose regional bit allocation (RBA) and rate distortion optimization (RDO) algorithms for multiview depth video coding (MDVC) by allocating more bits on CTAD for rendering quality and fewer bits on CSAD for compression efficiency. Experimental results show that the proposed VSDM based RBA and RDO can improve the coding efficiency significantly for the test sequences. In addition, for the proposed overall MDVC algorithm that integrates VSDM based RBA and RDO, it achieves 9.99% and 14.51% bit rate reduction on average for the high and low bit rate, respectively. It can improve virtual view image quality 0.22 and 0.24 dB on average at the high and low bit rate, respectively, when compared with the original joint multiview video coding model. The RD performance comparisons using five different metrics also validate the effectiveness of the proposed overall algorithm. In addition, the proposed algorithms can be applied to both INTRA and INTER frames.

  12. Experimental demonstration of realizability of optical focus wave modes

    NASA Astrophysics Data System (ADS)

    Reivelt, Kaido; Saari, Peeter

    2002-11-01

    The homogeneous scalar wave equation has a number of so-called localized wave (LW) solutions, instantaneous, Gaussian pulselike intensity distribution of which propagates without any spread or distortions in free space. Despite the undoubtedly intriguing properties and considerable effort that has been made to implement such wave fields, in the optical domain only their limiting case-the so-called Bessel-X pulses-has been experimentally launched so far. In this paper we report on experimental evidence of the optical realizability of the ``fundamental'' special case of the LW's-the focus wave modes.

  13. An experimental investigation of compressor stall using an on-line distortion indicator and signal conditioner

    NASA Technical Reports Server (NTRS)

    Costakis, W. G.; Wenzel, L. M.

    1975-01-01

    The relation of the steady-state and dynamic distortions and the stall margin of a J85-13 turbojet engine was investigated. A distortion indicator capable of computing two distortion indices was used. A special purpose signal conditioner was also used as an interface between transducer signals and distortion indicator. A good correlation of steady-state distortion and stall margin was established. The prediction of stall by using the indices as instantaneous distortion indicators was not successful. A sensitivity factor that related the loss of stall margin to the turbulence level was found.

  14. Analysis of internal wave reflection within a magnetostrictive patch transducer for high-frequency guided torsional waves.

    PubMed

    Kim, Hoe Woong; Cho, Seung Hyun; Kim, Yoon Young

    2011-08-01

    Recently, megahertz-range torsional waves have been successfully generated and measured by a magnetostrictive patch transducer employing a meander coil. But the waveform of a high-frequency torsional wave generated by magnetostrictive patch transducers becomes greatly distorted with multiple trailing pulses. The hypothesis explaining the cause of the waveform distortion is that the distortion results mainly from the internal wave reflection within the magnetostrictive patch, which is in turn caused by the impedance mismatch between the bare and patch-bonded parts of the pipe. Based on the hypothesis, we developed an analytic model for internal reflection simulation and conducted several experiments using a patch transducer to verify the hypothesis. The comparison of the analytical and experimental results showed that the internal reflection at the edge of the patch was responsible for the distortion of the measured waveform. The present study also confirmed that the standard acoustic impedance matching to avoid sudden discontinuities at the patch edges can effectively reduce the internal reflection and alleviate the waveform distortion problem. PMID:21420708

  15. Analysis of internal wave reflection within a magnetostrictive patch transducer for high-frequency guided torsional waves.

    PubMed

    Kim, Hoe Woong; Cho, Seung Hyun; Kim, Yoon Young

    2011-08-01

    Recently, megahertz-range torsional waves have been successfully generated and measured by a magnetostrictive patch transducer employing a meander coil. But the waveform of a high-frequency torsional wave generated by magnetostrictive patch transducers becomes greatly distorted with multiple trailing pulses. The hypothesis explaining the cause of the waveform distortion is that the distortion results mainly from the internal wave reflection within the magnetostrictive patch, which is in turn caused by the impedance mismatch between the bare and patch-bonded parts of the pipe. Based on the hypothesis, we developed an analytic model for internal reflection simulation and conducted several experiments using a patch transducer to verify the hypothesis. The comparison of the analytical and experimental results showed that the internal reflection at the edge of the patch was responsible for the distortion of the measured waveform. The present study also confirmed that the standard acoustic impedance matching to avoid sudden discontinuities at the patch edges can effectively reduce the internal reflection and alleviate the waveform distortion problem.

  16. Nonlinear propagation and control of acoustic waves in phononic superlattices

    NASA Astrophysics Data System (ADS)

    Jiménez, Noé; Mehrem, Ahmed; Picó, Rubén; García-Raffi, Lluís M.; Sánchez-Morcillo, Víctor J.

    2016-05-01

    The propagation of intense acoustic waves in a one-dimensional phononic crystal is studied. The medium consists in a structured fluid, formed by a periodic array of fluid layers with alternating linear acoustic properties and quadratic nonlinearity coefficient. The spacing between layers is of the order of the wavelength, therefore Bragg effects such as band gaps appear. We show that the interplay between strong dispersion and nonlinearity leads to new scenarios of wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps. This allows the possibility of engineer a medium in order to get a particular waveform. Examples of this include the design of media with effective (e.g., cubic) nonlinearities, or extremely linear media (where distortion can be canceled). The presented ideas open a way towards the control of acoustic wave propagation in nonlinear regime. xml:lang="fr"

  17. Pulse-coupled neural nets: translation, rotation, scale, distortion, and intensity signal invariance for images.

    PubMed

    Johnson, J L

    1994-09-10

    The linking-field neural network model of Eckhorn et al. [Neural Comput. 2, 293-307 (1990)] was introduced to explain the experimentally observed synchronous activity among neural assemblies in the cat cortex induced by feature-dependent visual activity. The model produces synchronous bursts of pulses from neurons with similar activity, effectively grouping them by phase and pulse frequency. It gives a basic new function: grouping by similarity. The synchronous bursts are obtained in the limit of strong linking strengths. The linking-field model in the limit of moderate-to-weak linking characterized by few if any multiple bursts is investigated. In this limit dynamic, locally periodic traveling waves exist whose time signal encodes the geometrical structure of a two-dimensional input image. The signal can be made insensitive to translation, scale, rotation, distortion, and intensity. The waves transmit information beyond the physical interconnect distance. The model is implemented in an optical hybrid demonstration system. Results of the simulations and the optical system are presented.

  18. Bit timing with pulse distortion and intersymbol interference

    NASA Technical Reports Server (NTRS)

    Gagliardi, R. M.

    1977-01-01

    Pulse distortion and intersymbol interference due to insufficient filtering in PCM and PSK channels cause performance degradation in terms of both bit error probabilities and timing errors. This paper reports the results of a study analyzing these effects on bit timing subsystems. Consideration is given to both the filter-rectifier and transition tracking type of timing subsystem. Although both these systems perform similarly in high SNR and ideal pulse models, pulse distortion and intersymbol affects each differently. The primary effects in both systems is to cause the presence of an irreducible mean squared timing error due to the intersymbol which limits the ultimate performance. Design procedures to minimize the anomalies of both systems are presented, and indicate modifications of the standard timing subsystems. It is found that specific design directions depend on whether the intersymbol or the receiver noise tends to dominate.

  19. Investigating the variability of memory distortion for an analogue trauma.

    PubMed

    Strange, Deryn; Takarangi, Melanie K T

    2015-01-01

    In this paper, we examine whether source monitoring (SM) errors might be one mechanism that accounts for traumatic memory distortion. Participants watched a traumatic film with some critical (crux) and non-critical (non-crux) scenes removed. Twenty-four hours later, they completed a memory test. To increase the likelihood participants would notice the film's gaps, we inserted visual static for the length of each missing scene. We then added manipulations designed to affect people's SM behaviour. To encourage systematic SM, before watching the film, we warned half the participants that we had removed some scenes. To encourage heuristic SM some participants also saw labels describing the missing scenes. Adding static highlighting, the missing scenes did not affect false recognition of those missing scenes. However, a warning decreased, while labels increased, participants' false recognition rates. We conclude that manipulations designed to affect SM behaviour also affect the degree of memory distortion in our paradigm.

  20. High thermoelectric performance of the distorted bismuth(110) layer.

    PubMed

    Cheng, L; Liu, H J; Zhang, J; Wei, J; Liang, J H; Jiang, P H; Fan, D D; Sun, L; Shi, J

    2016-07-14

    The thermoelectric properties of the distorted bismuth(110) layer are investigated using first-principles calculations combined with the Boltzmann transport equation for both electrons and phonons. To accurately predict the electronic and transport properties, the quasiparticle corrections with the GW approximation of many-body effects have been explicitly included. It is found that a maximum ZT value of 6.4 can be achieved for n-type systems, which essentially stemmed from the weak scattering of electrons. Moreover, we demonstrate that the distorted Bi layer retains high ZT values in relatively broad regions of both temperature and carrier concentration. Our theoretical work emphasizes that the deformation potential constant characterizing the electron-phonon scattering strength is an important paradigm for searching high thermoelectric performance materials. PMID:27302907

  1. Minimizing distortion in truss structures - A Hopfield network solution

    NASA Technical Reports Server (NTRS)

    Fu, B.; Hajela, P.

    1992-01-01

    Distortions in truss structures can result from random errors in element lengths that are typical of a manufacturing process. These distortions may be minimized by an optimal selection of elements from those available for placement between the prescribed nodes - a combinatorial optimization problem requiring significant investment of computational resource for all but the smallest problems. The present paper describes a formulation in which near-optimal element assignments are obtained as minimum-energy stable states, of an analogous Hopfield neural network. This requires mapping of the optimization problem into an energy function of the appropriate Liapunov form. The computational architecture is ideally suited to a parallel processor implementation and offers significant savings in computational effort. A numerical implementation of the approach is discussed with reference to planar truss problems.

  2. Minimizing distortion in truss structures -- a Hopfield network solution

    NASA Technical Reports Server (NTRS)

    Fu, B.; Hajela, P.

    1993-01-01

    Distortions in truss structures can result from random errors in elemental lengths that are typical of a manufacturing process. These distortions may be minimized by an optimal selection of elements from those available for placement between the prescribed nodes -- a combinatorial optimization problem requiring significant investment of computational resource for all but the smallest problems. The present paper describes a formulation in which near-optimal element assignments are obtained as minimum energy, stable states, of an analogous Hopfield neural network. This requires mapping of the optimization problem into an energy function of the appropriate Lyapunov form. The computational architecture is ideally suited to a parallel processor implementation and offers significant savings in computational effort. A numerical implementation of the approach is discussed with reference to planar truss problems.

  3. Sleep Wrinkles: Facial Aging and Facial Distortion During Sleep.

    PubMed

    Anson, Goesel; Kane, Michael A C; Lambros, Val

    2016-09-01

    Wrinkles are just one indicator of facial aging, but an indicator that is of prime importance in our world of facial aesthetics. Wrinkles occur where fault lines develop in aging skin. Those fault lines may be due to skin distortion resulting from facial expression or may be due to skin distortion from mechanical compression during sleep. Expression wrinkles and sleep wrinkles differ in etiology, location, and anatomical pattern. Compression, shear, and stress forces act on the face in lateral or prone sleep positions. We review the literature relating to the development of wrinkles and the biomechanical changes that occur in response to intrinsic and extrinsic influences. We explore the possibility that compression during sleep not only results in wrinkles but may also contribute to facial skin expansion. PMID:27329660

  4. Analysis and validation of laser spot weld-induced distortion

    SciTech Connect

    Knorovsky, G.A.; Kanouff, M.P.; Maccallum, D.O.; Fuerschbach, P.W.

    1999-12-09

    Laser spot welding is an ideal process for joining small parts with tight tolerances on weld size, location, and distortion, particularly those with near-by heat sensitive features. It is also key to understanding the overlapping laser spot seam welding process. Rather than attempting to simulate the laser beam-to-part coupling (particularly if a keyhole occurs), it was measured by calorimetry. This data was then used to calculate the thermal and structural response of a laser spot welded SS304 disk using the finite element method. Five combinations of process parameter values were studied. Calculations were compared to experimental data for temperature and distortion profiles measured by thermocouples and surface profiling. Results are discussed in terms of experimental and modeling factors. The authors then suggest appropriate parameters for laser spot welding.

  5. Mapping flow distortion on oceanographic platforms using computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    O'Sullivan, N.; Landwehr, S.; Ward, B.

    2013-10-01

    Wind speed measurements over the ocean on ships or buoys are affected by flow distortion from the platform and by the anemometer itself. This can lead to errors in direct measurements and the derived parametrisations. Here we computational fluid dynamics (CFD) to simulate the errors in wind speed measurements caused by flow distortion on the RV Celtic Explorer. Numerical measurements were obtained from the finite-volume CFD code OpenFOAM, which was used to simulate the velocity fields. This was done over a range of orientations in the test domain from -60 to +60° in increments of 10°. The simulation was also set up for a range of velocities, ranging from 5 to 25 m s-1 in increments of 0.5 m s-1. The numerical analysis showed close agreement to experimental measurements.

  6. Electrohydrodynamic distortion of sample streams in continuous flow electrophoresis

    NASA Technical Reports Server (NTRS)

    Rhodes, Percy H.; Snyder, Robert S.; Roberts, Glyn O.

    1989-01-01

    Continuous flow electrophoresis experiments were carried out, using an electrolyte and a sample both made of aqueous solutions of phosphate buffer (with polystyrene latex added for visibility), to investigate causes of the sample spreading in this procedure. It is shown theoretically that an electric field perpendicular to a circular filament of conducting fluid surrounded by a fluid of different conductivity produces an electrohydrodynamic flow, which distorts the filament into an ellipse. Experimental results were found to be fully consistent with theretical predictions. It was found that the rate of distortion of the sample stream into a ribbon was proportional to the square of the applied voltage gradient. Furthermore, the orientation of the ribbon depends on the ratios of dielectric constant and electrical conductivity between the buffer and the sample.

  7. Investigating the variability of memory distortion for an analogue trauma.

    PubMed

    Strange, Deryn; Takarangi, Melanie K T

    2015-01-01

    In this paper, we examine whether source monitoring (SM) errors might be one mechanism that accounts for traumatic memory distortion. Participants watched a traumatic film with some critical (crux) and non-critical (non-crux) scenes removed. Twenty-four hours later, they completed a memory test. To increase the likelihood participants would notice the film's gaps, we inserted visual static for the length of each missing scene. We then added manipulations designed to affect people's SM behaviour. To encourage systematic SM, before watching the film, we warned half the participants that we had removed some scenes. To encourage heuristic SM some participants also saw labels describing the missing scenes. Adding static highlighting, the missing scenes did not affect false recognition of those missing scenes. However, a warning decreased, while labels increased, participants' false recognition rates. We conclude that manipulations designed to affect SM behaviour also affect the degree of memory distortion in our paradigm. PMID:25105759

  8. Ultrasonic inspection apparatus and method using a focused wave device

    DOEpatents

    Gieske, John H.; Roach, Dennis P.; Walkington, Phillip D.

    2001-01-01

    An ultrasonic pulse echo inspection apparatus and method for detecting structural failures. A focus lens is coupled to the transducer to focus the ultrasonic signal on an area to be inspected and a stop is placed in the focus lens to block selected ultrasonic waves. Other waves are not blocked and are transmitted through the structure to arrive at interfaces therein concurrently to produce an echo response with significantly less distortion.

  9. Breast tissue decomposition with spectral distortion correction: A postmortem study

    SciTech Connect

    Ding, Huanjun; Zhao, Bo; Baturin, Pavlo; Behroozi, Farnaz; Molloi, Sabee

    2014-10-15

    Purpose: To investigate the feasibility of an accurate measurement of water, lipid, and protein composition of breast tissue using a photon-counting spectral computed tomography (CT) with spectral distortion corrections. Methods: Thirty-eight postmortem breasts were imaged with a cadmium-zinc-telluride-based photon-counting spectral CT system at 100 kV. The energy-resolving capability of the photon-counting detector was used to separate photons into low and high energy bins with a splitting energy of 42 keV. The estimated mean glandular dose for each breast ranged from 1.8 to 2.2 mGy. Two spectral distortion correction techniques were implemented, respectively, on the raw images to correct the nonlinear detector response due to pulse pileup and charge-sharing artifacts. Dual energy decomposition was then used to characterize each breast in terms of water, lipid, and protein content. In the meantime, the breasts were chemically decomposed into their respective water, lipid, and protein components to provide a gold standard for comparison with dual energy decomposition results. Results: The accuracy of the tissue compositional measurement with spectral CT was determined by comparing to the reference standard from chemical analysis. The averaged root-mean-square error in percentage composition was reduced from 15.5% to 2.8% after spectral distortion corrections. Conclusions: The results indicate that spectral CT can be used to quantify the water, lipid, and protein content in breast tissue. The accuracy of the compositional analysis depends on the applied spectral distortion correction technique.

  10. Experimental dead-time distortions of poisson processes

    NASA Astrophysics Data System (ADS)

    Faraci, G.; Pennisi, A. R.

    1983-07-01

    In order to check the distortions, introduced by a non-extended dead time on the Poisson statistics, accurate experiments have been made in single channel counting. At a given measuring time, the dependence on the choice of the time origin and on the width of the dead time has been verified. An excellent agreement has been found between the theoretical expressions and the experimental curves.

  11. Using unstable periodic orbits to overcome distortion in chaotic signals.

    PubMed

    Carroll, T L

    1999-11-01

    Proposals to use chaos for communications have been hindered by the fact that broadband chaotic signals are distorted by narrow band or frequency dependent communications channels. I show in this paper how the unstable periodic orbits from a chaotic attractor may be used to estimate the parameters of a filter that has acted on a signal from that attractor and estimate the chaotic signal, even when additive noise larger than the chaotic signal is present. PMID:11970420

  12. Control of Inflow Distortion in a Scarf Inlet

    NASA Technical Reports Server (NTRS)

    Gerhold, Carl H.; Clark, Lorenzo R.; Biedron, Robert T.

    2002-01-01

    The scarf inlet has the potential to reduce aircraft inlet noise radiation to the ground by reflecting it into the space above the engine. Without forward motion of the engine, the non-symmetry of the inlet causes inflow distortion which generates noise that is greater than the noise reduction of the scarf. However, acoustic evaluations of aircraft engines are often done on static test stands. A method to reduce inflow distortion by boundary layer suction is proposed and evaluated using a model of a high bypass ratio engine located in an anechoic chamber. The design goal of the flow control system is to make the inflow to the inlet circumferentially uniform and to eliminate reversed flow. This minimizes the inflow distortion and allows for acoustic evaluation of the scarf inlet on a static test stand. The inlet boundary layer suction effectiveness is evaluated both by aerodynamic and by acoustic measurements. Although the design goal is not met, the control system is found to have a beneficial effect on the engine operation, reducing blade stall and speed variation. This is quantified by two acoustic benefits, reduction both of the variability of tone noise and of the low frequency wideband noise due to the inflow distortion. It is felt that a compromise in the manufacture of the control hardware contributes to the inability of the control system to perform as expected from the analysis. The control system with sufficient authority is felt to have the potential to permit reliable acoustic testing in a static configuration of engines with non-symmetric inlets. Because the control system can improve operation of the engine, it may also have the potential to reduce noise and vibration and enhance engine longevity during low speed ground operations in the terminal area.

  13. Reduction of sextupole distortion by shuffling magnets in small groups

    SciTech Connect

    Gluckstern, R.L.; Ohnuma, S.

    1985-05-01

    A method is given for reducing the most troublesome sextupole harmonics in a ring by measuring the sextupole field in groups of magnets, and ordering them according to a predetermined prescription. The predicted result is a decrease in sextupole related distortions by a factor ..sqrt..2/(J+1)/sup 1/2/ where J magnets, covering one or more betatron periods, are measured at one time. Simulations performed for typical SSC lattices confirm the expected improvements.

  14. System overview on electromagnetic compensation for reflector antenna surface distortion

    NASA Technical Reports Server (NTRS)

    Acosta, R. J.; Zaman, A. J.; Terry, J. D.

    1993-01-01

    The system requirements and hardware implementation for electromagnetic compensation of antenna performance degradations due to thermal effects was investigated. Future commercial space communication antenna systems will utilize the 20/30 GHz frequency spectrum and support very narrow multiple beams (0.3 deg) over wide angle field of view (15-20 beamwidth). On the ground, portable and inexpensive very small aperture terminals (VSAT) for transmitting and receiving video, facsimile and data will be employed. These types of communication system puts a very stringent requirement on spacecraft antenna beam pointing stability (less than .01 deg), high gain (greater than 50 dB) and very lowside lobes (less than -25 dB). Thermal analysis performed on the advanced communication technology satellite (ACTS) has shown that the reflector surfaces, the mechanical supporting structures and metallic surfaces on the spacecraft body will distort due thermal effects from a varying solar flux. The antenna performance characteristics (e.g., pointing stability, gain, side lobe, etc.) will degrade due to thermal distortion in the reflector surface and supporting structures. Specifically, antenna RF radiation analysis has shown that pointing error is the most sensitive antenna performance parameter to thermal distortions. Other antenna parameters like peak gain, cross polarization level (beam isolation), and side lobe level will also degrade with thermal distortions. In order to restore pointing stability and in general antenna performance several compensation methods were proposed. In general these compensation methods can be classified as being either of mechanical or electromagnetic type. This paper will address only the later one. In this approach an adaptive phased array antenna feed is used to compensate for the antenna performance degradation. Extensive work has been devoted to demonstrate the feasibility of adaptive feed compensation on space communication antenna systems. This

  15. Transient flows and pressure waves in pipes

    SciTech Connect

    Wang, X.Q.; Sun, J.G.; Sha, W.T.

    1994-06-01

    Transient laminar flows and pressure-wave propagations in pipes connected with components, commonly known as water hammer, are analyzed. The system studied consists of a constant-pressure vessel, a uniform circular pipe, a valve between them, and a receiver vessel. A pressure-wave equation and a linearized velocity equation are derived from the equations of mass and momentum conservation. Waveform distortion due to viscous dissipation and pipe-wall elastic expansion is characterized by a dimensionless transmission number, K. The coefficients of the damping of the pressure waves were found to be related to the roots of the Bessel function J{sub 0}. An exact solution of the pressure-wave equation was obtained numerically. The relationship between the distortion of a traveling wave and the transmission number K was studied. The problem is also calculated with a general-purpose computer code, COMMIX, which solves the exact mass conservation equation and Navier-Stokes equations. The COMMIX calculational results agreed well with the analytical solutions.

  16. Rectification of terrain induced distortions in radar imagery

    NASA Technical Reports Server (NTRS)

    Kwok, Ronald; Curlander, John C.; Pang, Shirley S.

    1987-01-01

    This paper describes a technique to generate geocoded synthetic aperture radar (SAR) imagery corrected for terrain induced geometric distortions. This algorithm transforms the raw slant range image, generated by the signal processor, into a map registered product, resampled to either Universal Transverse Mercator (UTM) or Polar Stereographic projections, and corrected for foreshortening. The technique utilizes the space platform trajectory information in conjunction with a digital elevation map (DEM) of the target area to generate an ortho-radar map with near-autonomous operation. The current procedure requires only two to three tie-points to compensate for the platform position uncertainty that results in translational error between the image and the DEM. This approach is unique in that it does not require generation of a simulated radar image from the DEM or a grid of tie-points to characterize the image-to-map distortions. Rather, it models the inherent distortions based on knowledge of the radar data collection characteristics, the signal Doppler parameters, and the local terrain height to automatically predict the registration transformation. This algorithm has been implemented on a minicomputer system equipped with an array processor and a large random-access memory to optimize the throughput.

  17. [An improved low spectral distortion PCA fusion method].

    PubMed

    Peng, Shi; Zhang, Ai-Wu; Li, Han-Lun; Hu, Shao-Xing; Meng, Xian-Gang; Sun, Wei-Dong

    2013-10-01

    Aiming at the spectral distortion produced in PCA fusion process, the present paper proposes an improved low spectral distortion PCA fusion method. This method uses NCUT (normalized cut) image segmentation algorithm to make a complex hyperspectral remote sensing image into multiple sub-images for increasing the separability of samples, which can weaken the spectral distortions of traditional PCA fusion; Pixels similarity weighting matrix and masks were produced by using graph theory and clustering theory. These masks are used to cut the hyperspectral image and high-resolution image into some sub-region objects. All corresponding sub-region objects between the hyperspectral image and high-resolution image are fused by using PCA method, and all sub-regional integration results are spliced together to produce a new image. In the experiment, Hyperion hyperspectral data and Rapid Eye data were used. And the experiment result shows that the proposed method has the same ability to enhance spatial resolution and greater ability to improve spectral fidelity performance. PMID:24409735

  18. Applying image quality in cell phone cameras: lens distortion

    NASA Astrophysics Data System (ADS)

    Baxter, Donald; Goma, Sergio R.; Aleksic, Milivoje

    2009-01-01

    This paper describes the framework used in one of the pilot studies run under the I3A CPIQ initiative to quantify overall image quality in cell-phone cameras. The framework is based on a multivariate formalism which tries to predict overall image quality from individual image quality attributes and was validated in a CPIQ pilot program. The pilot study focuses on image quality distortions introduced in the optical path of a cell-phone camera, which may or may not be corrected in the image processing path. The assumption is that the captured image used is JPEG compressed and the cellphone camera is set to 'auto' mode. As the used framework requires that the individual attributes to be relatively perceptually orthogonal, in the pilot study, the attributes used are lens geometric distortion (LGD) and lateral chromatic aberrations (LCA). The goal of this paper is to present the framework of this pilot project starting with the definition of the individual attributes, up to their quantification in JNDs of quality, a requirement of the multivariate formalism, therefore both objective and subjective evaluations were used. A major distinction in the objective part from the 'DSC imaging world' is that the LCA/LGD distortions found in cell-phone cameras, rarely exhibit radial behavior, therefore a radial mapping/modeling cannot be used in this case.

  19. How Geometric Distortions Scatter Electronic Excitations in Conjugated Macromolecules.

    PubMed

    Shi, Tian; Li, Hao; Tretiak, Sergei; Chernyak, Vladimir Y

    2014-11-20

    Effects of disorder and exciton-phonon interactions are the major factors controlling photoinduced dynamics and energy-transfer processes in conjugated organic semiconductors, thus defining their electronic functionality. All-atom quantum-chemical simulations are potentially capable of describing such phenomena in complex "soft" organic structures, yet they are frequently computationally restrictive. Here we efficiently characterize how electronic excitations in branched conjugated molecules interact with molecular distortions using the exciton scattering (ES) approach as a fundamental principle combined with effective tight-binding models. Molecule geometry deformations are incorporated to the ES view of electronic excitations by identifying the dependence of the Frenkel-type exciton Hamiltonian parameters on the characteristic geometry parameters. We illustrate our methodology using two examples of intermolecular distortions, bond length alternation and single bond rotation, which constitute vibrational degrees of freedom strongly coupled to the electronic system in a variety of conjugated systems. The effect on excited-state electronic structures has been attributed to localized variation of exciton on-site energies and couplings. As a result, modifications of the entire electronic spectra due to geometric distortions can be efficiently and accurately accounted for with negligible numerical cost. The presented approach can be potentially extended to model electronic structures and photoinduced processes in bulk amorphous polymer materials. PMID:26276475

  20. Influence of Rewetting Behavior on the Distortion of Bearing Races

    NASA Astrophysics Data System (ADS)

    Lübben, Thomas; Frerichs, Friedhelm

    2013-08-01

    Immersion quenching in evaporable fluids like oil, polymer solutions, or water is a widely used technique in heat treatment shops because this technique provides higher heat transfer coefficients than the most alternative gas quenching techniques. The disadvantages of immersion quenching in evaporating fluids are the complex heat transfer mechanisms which consist of the three phases, film boiling, nucleate boiling, and convection. Especially the transition from film to nucleate boiling—the rewetting of the sample surface—is a complex process which leads to a strong position dependence of the heat transfer coefficient of the cooled work pieces. In particular, immersion quenching of thin-walled rings can result in large changes of ovality with comparable high scattering. To understand these results, two series of experiments were performed. Rings were quenched in oil in a special quenching tank and the rewetting behavior was documented. Furthermore, bearing races were quenched in a standard tank. Before and after heat treatment, these rings were measured by a coordinate measuring system and the distortion was determined. The investigations have clearly shown that the vapor film can have an important influence on distortion generation during oil quenching. The resulting distortion can principally be explained by the observed rewetting behavior.

  1. How Geometric Distortions Scatter Electronic Excitations in Conjugated Macromolecules.

    PubMed

    Shi, Tian; Li, Hao; Tretiak, Sergei; Chernyak, Vladimir Y

    2014-11-20

    Effects of disorder and exciton-phonon interactions are the major factors controlling photoinduced dynamics and energy-transfer processes in conjugated organic semiconductors, thus defining their electronic functionality. All-atom quantum-chemical simulations are potentially capable of describing such phenomena in complex "soft" organic structures, yet they are frequently computationally restrictive. Here we efficiently characterize how electronic excitations in branched conjugated molecules interact with molecular distortions using the exciton scattering (ES) approach as a fundamental principle combined with effective tight-binding models. Molecule geometry deformations are incorporated to the ES view of electronic excitations by identifying the dependence of the Frenkel-type exciton Hamiltonian parameters on the characteristic geometry parameters. We illustrate our methodology using two examples of intermolecular distortions, bond length alternation and single bond rotation, which constitute vibrational degrees of freedom strongly coupled to the electronic system in a variety of conjugated systems. The effect on excited-state electronic structures has been attributed to localized variation of exciton on-site energies and couplings. As a result, modifications of the entire electronic spectra due to geometric distortions can be efficiently and accurately accounted for with negligible numerical cost. The presented approach can be potentially extended to model electronic structures and photoinduced processes in bulk amorphous polymer materials.

  2. Two Dimensional Intermodulation Distortion Scanning of Superconducting Filter Resonators

    NASA Astrophysics Data System (ADS)

    Bischak, Michael; Remillard, Stephen

    2015-03-01

    Nonlinear superconducting conductivity produces distortion that has usually been measured globally across the entire sample. In order to fully understand the origin of non linearity, local methods must be used to examine specific points in the sample. The nonlinear Ohm's law, V =IZ(I) includes the current dependence in the impedance. The method in this work raster scans a magnetic loop probe across a sample. In order to address limited resolution, we reduced the size of the magnetic loop probe. Using the electromagnetic field solver, sonnet, two dimensional current simulations of superconducting microwave filters composed of Tl2Ba2CaCu2O8 or of YBa2Cu3O7 reveal microwave current which is bunched up at the corners and sides of the sample. Two dimensional images of third order intermodulation distortion made with the magnetic probe at the same corners and edges reveal elevated distortion in the same places. Using the magnetic probe, third order intermodulation was seen to come from the same corners and edges where the current is bunched. This research was funded by the National Science Foundation under grant number DMR-1206149.

  3. Damage to insula abolishes cognitive distortions during simulated gambling

    PubMed Central

    Clark, Luke; Studer, Bettina; Bruss, Joel; Tranel, Daniel; Bechara, Antoine

    2014-01-01

    Gambling is a naturalistic example of risky decision-making. During gambling, players typically display an array of cognitive biases that create a distorted expectancy of winning. This study investigated brain regions underpinning gambling-related cognitive distortions, contrasting patients with focal brain lesions to the ventromedial prefrontal cortex (vmPFC), insula, or amygdala (“target patients”) against healthy comparison participants and lesion comparison patients (i.e., with lesions that spare the target regions). A slot machine task was used to deliver near-miss outcomes (i.e., nonwins that fall spatially close to a jackpot), and a roulette game was used to examine the gambler’s fallacy (color decisions following outcome runs). Comparison groups displayed a heightened motivation to play following near misses (compared with full misses), and manifested a classic gambler’s fallacy effect. Both effects were also observed in patients with vmPFC and amygdala damage, but were absent in patients with insula damage. Our findings indicate that the distorted cognitive processing of near-miss outcomes and event sequences may be ordinarily supported by the recruitment of the insula. Interventions to reduce insula reactivity could show promise in the treatment of disordered gambling. PMID:24711387

  4. Compressed image quality metric based on perceptually weighted distortion.

    PubMed

    Hu, Sudeng; Jin, Lina; Wang, Hanli; Zhang, Yun; Kwong, Sam; Kuo, C-C Jay

    2015-12-01

    Objective quality assessment for compressed images is critical to various image compression systems that are essential in image delivery and storage. Although the mean squared error (MSE) is computationally simple, it may not be accurate to reflect the perceptual quality of compressed images, which is also affected dramatically by the characteristics of human visual system (HVS), such as masking effect. In this paper, an image quality metric (IQM) is proposed based on perceptually weighted distortion in terms of the MSE. To capture the characteristics of HVS, a randomness map is proposed to measure the masking effect and a preprocessing scheme is proposed to simulate the processing that occurs in the initial part of HVS. Since the masking effect highly depends on the structural randomness, the prediction error from neighborhood with a statistical model is used to measure the significance of masking. Meanwhile, the imperceptible signal with high frequency could be removed by preprocessing with low-pass filters. The relation is investigated between the distortions before and after masking effect, and a masking modulation model is proposed to simulate the masking effect after preprocessing. The performance of the proposed IQM is validated on six image databases with various compression distortions. The experimental results show that the proposed algorithm outperforms other benchmark IQMs. PMID:26415170

  5. Automatic estimation and compensation of geometric distortions in video copies

    NASA Astrophysics Data System (ADS)

    Chupeau, B.; Massoudi, A.; Lefèbvre, F.

    2007-01-01

    The proliferation of pirate copies of feature films on peer-to-peer networks arouses a great interest to countermeasures such as the insertion of (invisible) forensic marks in projected movies, to deter their illegal capture. The registration of pirate copies with the original content is however a prerequisite to the recovery of such embedded messages, as severe geometric distortions often occur in illegally camcorded contents. After a brief state-of-the-art in image registration, the paper details an algorithm for video registration, focusing on the compensation of geometric distortions. Control points are automatically extracted in original and copy pictures, followed by pre- and post-matching filtering steps to discard not relevant control points and erroneous matched pairs of control points respectively. This enables the accurate numerical estimation of an 8-parameter homographic distortion model, used to register the copy frames with the original reference grid. Such an image registration algorithm is inserted into a general video registration scheme. Results are presented on both natural and synthetic test material.

  6. Cartographic distortions make dielectric spacetime analog models imperfect mimickers

    NASA Astrophysics Data System (ADS)

    Fathi, Mohsen; Thompson, Robert T.

    2016-06-01

    It is commonly assumed that if the optical metric of a dielectric medium is identical to the metric of a vacuum space-time then light propagation through the dielectric mimics light propagation in the vacuum. However, just as the curved surface of the Earth cannot be mapped into a flat plane without distortion of some surface features, so too is it impossible to project the behavior of light from the vacuum into a dielectric analog residing in Minkowski space-time without introducing distortions. We study the covariance properties of dielectric analog space-times and the kinematics of a congruence of light in the analog, and show how certain features can be faithfully emulated in the analog depending on the choice of projection, but that not all features can be simultaneously emulated without distortion. These findings indicate conceptual weaknesses in the idea of using analog space-times as a basis for transformation optics, and we show that a certain formulation of transformation optics closely related to analog space-times resolves these issues.

  7. Damage to insula abolishes cognitive distortions during simulated gambling.

    PubMed

    Clark, Luke; Studer, Bettina; Bruss, Joel; Tranel, Daniel; Bechara, Antoine

    2014-04-22

    Gambling is a naturalistic example of risky decision-making. During gambling, players typically display an array of cognitive biases that create a distorted expectancy of winning. This study investigated brain regions underpinning gambling-related cognitive distortions, contrasting patients with focal brain lesions to the ventromedial prefrontal cortex (vmPFC), insula, or amygdala ("target patients") against healthy comparison participants and lesion comparison patients (i.e., with lesions that spare the target regions). A slot machine task was used to deliver near-miss outcomes (i.e., nonwins that fall spatially close to a jackpot), and a roulette game was used to examine the gambler's fallacy (color decisions following outcome runs). Comparison groups displayed a heightened motivation to play following near misses (compared with full misses), and manifested a classic gambler's fallacy effect. Both effects were also observed in patients with vmPFC and amygdala damage, but were absent in patients with insula damage. Our findings indicate that the distorted cognitive processing of near-miss outcomes and event sequences may be ordinarily supported by the recruitment of the insula. Interventions to reduce insula reactivity could show promise in the treatment of disordered gambling.

  8. Achieving high visibility in subcarrier wave quantum key distribution system

    NASA Astrophysics Data System (ADS)

    Chistyakov, V. V.; Smirnov, S. V.; Nazarov, Yu V.; Kynev, S. M.; Gleim, A. V.

    2016-08-01

    We study influence of quantum signal polarization distortions in the optical fiber on the interference pattern visibility in a subcarrier wave quantum key distribution system. An optical scheme of the polarization compensation unit is suggested, and dynamics of the QBER depending on the unit architecture is explored.

  9. Lens distortion elimination for improving measurement accuracy of fringe projection profilometry

    NASA Astrophysics Data System (ADS)

    Li, Kai; Bu, Jingjie; Zhang, Dongsheng

    2016-10-01

    Fringe projection profilometry (FPP) is a powerful method for three-dimensional (3D) shape measurement. However, the measurement accuracy of the existing FPP is often hindered by the distortion of the lens used in FPP. In this paper, a simple and efficient method is presented to overcome this problem. First, the FPP system is calibrated as a stereovision system. Then, the camera lens distortion is eliminated by correcting the captured images. For the projector lens distortion, distorted fringe patterns are generated according to the lens distortion model. With these distorted fringe patterns, the projector can project undistorted fringe patterns, which means that the projector lens distortion is eliminated. Experimental results show that the proposed method can successfully eliminate the lens distortions of FPP and therefore improves its measurement accuracy.

  10. Automatic estimation and correction of anisotropic magnification distortion in electron microscopes.

    PubMed

    Grant, Timothy; Grigorieff, Nikolaus

    2015-11-01

    We demonstrate a significant anisotropic magnification distortion, found on an FEI Titan Krios microscope and affecting magnifications commonly used for data acquisition on a Gatan K2 Summit detector. We describe a program (mag_distortion_estimate) to automatically estimate anisotropic magnification distortion from a set of images of a standard gold shadowed diffraction grating. We also describe a program (mag_distortion_correct) to correct for the estimated distortion in collected images. We demonstrate that the distortion present on the Titan Krios microscope limits the resolution of a set of rotavirus VP6 images to ∼7 Å, which increases to ∼3 Å following estimation and correction of the distortion. We also use a 70S ribosome sample to demonstrate that in addition to affecting resolution, magnification distortion can also interfere with the classification of heterogeneous data.

  11. Phase-distortion correction based on stochastic parallel proportional-integral-derivative algorithm for high-resolution adaptive optics

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Wu, Ke-nan; Gao, Hong; Jin, Yu-qi

    2015-02-01

    A novel optimization method, stochastic parallel proportional-integral-derivative (SPPID) algorithm, is proposed for high-resolution phase-distortion correction in wave-front sensorless adaptive optics (WSAO). To enhance the global search and self-adaptation of stochastic parallel gradient descent (SPGD) algorithm, residual error and its temporal integration of performance metric are added in to incremental control signal's calculation. On the basis of the maximum fitting rate between real wave-front and corrector, a goal value of metric is set as the reference. The residual error of the metric relative to reference is transformed into proportional and integration terms to produce adaptive step size updating law of SPGD algorithm. The adaptation of step size leads blind optimization to desired goal and helps escape from local extrema. Different from conventional proportional-integral -derivative (PID) algorithm, SPPID algorithm designs incremental control signal as PI-by-D for adaptive adjustment of control law in SPGD algorithm. Experiments of high-resolution phase-distortion correction in "frozen" turbulences based on influence function coefficients optimization were carried out respectively using 128-by-128 typed spatial light modulators, photo detector and control computer. Results revealed the presented algorithm offered better performance in both cases. The step size update based on residual error and its temporal integration was justified to resolve severe local lock-in problem of SPGD algorithm used in high -resolution adaptive optics.

  12. Measurements of inlet flow distortions in an axial flow fan (6 and 9 blade rotor)

    NASA Technical Reports Server (NTRS)

    Barr, L. C.

    1978-01-01

    A large quantity of experimental data on inlet flow distortions in an axial flow fan were obtained. The purpose of the study was to determine the effects of design and operating variables and the type of distortion on the response of an axial flow turbomachinery rotor. Included are background information and overall trends observed in distortion attenuation and unsteady total pressure losses.

  13. Experimental evaluation of the effect of inlet distortion on compressor blade vibrations

    NASA Technical Reports Server (NTRS)

    Lubomski, J. F.

    1979-01-01

    Compressor rotor strain gage data from an engine test conducted with an inlet screen distortion were reduced and analyzed. These data are compared to data obtained from the same engine without inlet pressure distortion to determine the net effect of the distortion on the vibratory response of the compressor blades. The results obtained are presented.

  14. Feature maps driven no-reference image quality prediction of authentically distorted images

    NASA Astrophysics Data System (ADS)

    Ghadiyaram, Deepti; Bovik, Alan C.

    2015-03-01

    Current blind image quality prediction models rely on benchmark databases comprised of singly and synthetically distorted images, thereby learning image features that are only adequate to predict human perceived visual quality on such inauthentic distortions. However, real world images often contain complex mixtures of multiple distortions. Rather than a) discounting the effect of these mixtures of distortions on an image's perceptual quality and considering only the dominant distortion or b) using features that are only proven to be efficient for singly distorted images, we deeply study the natural scene statistics of authentically distorted images, in different color spaces and transform domains. We propose a feature-maps-driven statistical approach which avoids any latent assumptions about the type of distortion(s) contained in an image, and focuses instead on modeling the remarkable consistencies in the scene statistics of real world images in the absence of distortions. We design a deep belief network that takes model-based statistical image features derived from a very large database of authentically distorted images as input and discovers good feature representations by generalizing over different distortion types, mixtures, and severities, which are later used to learn a regressor for quality prediction. We demonstrate the remarkable competence of our features for improving automatic perceptual quality prediction on a benchmark database and on the newly designed LIVE Authentic Image Quality Challenge Database and show that our approach of combining robust statistical features and the deep belief network dramatically outperforms the state-of-the-art.

  15. Body Image Dissatisfaction and Distortion, Steroid Use, and Sex Differences in College Age Bodybuilders.

    ERIC Educational Resources Information Center

    Peters, Mark Anthony; Phelps, LeAddelle

    2001-01-01

    Compares college age bodybuilders by sex and steroid intake on two variables: body image dissatisfaction and body image distortion. Results reveal only a significant effect for gender on body distortion. No steroid-use differences were apparent for either body image dissatisfaction or body image distortion. Analyses indicate that female…

  16. Cognitive Distortions as Mediators between Life Stress and Depression in Adolescents.

    ERIC Educational Resources Information Center

    Deal, Saundra L.; Williams, John E.

    1988-01-01

    Administered measures of cognitive distortion, life stress, and depressive tendencies to 103 high school students. Findings were consistent with predictions that measures of cognitive distortion would be better predictors of depressive tendencies than were measures of life stress; cognitive distortions would affect perceived stressfulness of life…

  17. The reduction of the linear stability of elliptic Euler-Moulton solutions of the n-body problem to those of 3-body problems

    NASA Astrophysics Data System (ADS)

    Zhou, Qinglong; Long, Yiming

    2016-10-01

    In this paper, we consider the elliptic collinear solutions of the classical n-body problem, where the n bodies always stay on a straight line, and each of them moves on its own elliptic orbit with the same eccentricity. Such a motion is called an elliptic Euler-Moulton collinear solution. Here we prove that the corresponding linearized Hamiltonian system at such an elliptic Euler-Moulton collinear solution of n-bodies splits into (n-1) independent linear Hamiltonian systems, the first one is the linearized Hamiltonian system of the Kepler 2-body problem at Kepler elliptic orbit, and each of the other (n-2) systems is the essential part of the linearized Hamiltonian system at an elliptic Euler collinear solution of a 3-body problem whose mass parameter is modified. Then the linear stability of such a solution in the n-body problem is reduced to those of the corresponding elliptic Euler collinear solutions of the 3-body problems, which for example then can be further understood using numerical results of Martínez et al. on 3-body Euler solutions in 2004-2006. As an example, we carry out the detailed derivation of the linear stability for an elliptic Euler-Moulton solution of the 4-body problem with two small masses in the middle.

  18. Gravity waves

    NASA Technical Reports Server (NTRS)

    Fritts, David

    1987-01-01

    Gravity waves contributed to the establishment of the thermal structure, small scale (80 to 100 km) fluctuations in velocity (50 to 80 m/sec) and density (20 to 30%, 0 to peak). Dominant gravity wave spectrum in the middle atmosphere: x-scale, less than 100 km; z-scale, greater than 10 km; t-scale, less than 2 hr. Theorists are beginning to understand middle atmosphere motions. There are two classes: Planetary waves and equatorial motions, gravity waves and tidal motions. The former give rise to variability at large scales, which may alter apparent mean structure. Effects include density and velocity fluctuations, induced mean motions, and stratospheric warmings which lead to the breakup of the polar vortex and cooling of the mesosphere. On this scale are also equatorial quasi-biennial and semi-annual oscillations. Gravity wave and tidal motions produce large rms fluctuations in density and velocity. The magnitude of the density fluctuations compared to the mean density is of the order of the vertical wavelength, which grows with height. Relative density fluctuations are less than, or of the order of 30% below the mesopause. Such motions may cause significant and variable convection, and wind shear. There is a strong seasonal variation in gravity wave amplitude. Additional observations are needed to address and quantify mean and fluctuation statistics of both density and mean velocity, variability of the mean and fluctuations, and to identify dominant gravity wave scales and sources as well as causes of variability, both temporal and geographic.

  19. Atmospheric Waves

    NASA Technical Reports Server (NTRS)

    2007-01-01

    With its Multispectral Visible Imaging Camera (MVIC), half of the Ralph instrument, New Horizons captured several pictures of mesoscale gravity waves in Jupiter's equatorial atmosphere. Buoyancy waves of this type are seen frequently on Earth - for example, they can be caused when air flows over a mountain and a regular cloud pattern forms downstream. In Jupiter's case there are no mountains, but if conditions in the atmosphere are just right, it is possible to form long trains of these small waves. The source of the wave excitation seems to lie deep in Jupiter's atmosphere, below the visible cloud layers at depths corresponding to pressures 10 times that at Earth's surface. The New Horizons measurements showed that the waves move about 100 meters per second faster than surrounding clouds; this is about 25% of the speed of sound on Earth and is much greater than current models of these waves predict. Scientists can 'read' the speed and patterns these waves to learn more about activity and stability in the atmospheric layers below.

  20. Moreton Waves

    NASA Technical Reports Server (NTRS)

    Thompson, B. J.

    1999-01-01

    "Moreton waves," named for the observer who popularized them, are a solar phenomenon also known in scientific literature as "Moreton-Ramsey wave," "flare waves," "flare-associated waves," "MHD blast waves," "chromospheric shock fronts" and various other combinations of terms which connote violently propagating impulsive disturbances. It is unclear whether all of the observations to which these terms have been applied pertain to a single physical phenomenon: there has perhaps been some overlap between the observations and the assumed physical properties of the observed occurrence. Moreton waves are ideally observed in the wings of H alpha, and appear as semi-circular fronts propagating at speeds ranging from several hundred to over a thousand km/sec. They form an arc, or "brow shape" which can span up to 180 degrees. Extrapolating the speed and locations of the arc indicates that the phenomenon's origin intersects well with the impulsive phase of the associated H alpha flare (if the flare exhibits an impulsive phase). However, the arc may not form or may not be observable until it is tens of megameters from the flaring region, and subsequently can propagate to distances exceeding 100 megameters. The high speeds and distances of propagation, plus the associated radio and energetic particle observations, provided strong evidence of a coronal, rather than a chromospheric origin. The H alpha manifestation of the wave is assumed to be the "ground track" or "skirt" of a three-dimensional disturbance.

  1. Hot gas in superclusters and microwave background distortions

    NASA Technical Reports Server (NTRS)

    Persi, Fred M.; Spergel, David N.; Cen, Renyue; Ostriker, J. P.

    1995-01-01

    Variations in the electron pressure can produce significant distortions of the cosmic microwave background radiation (CMBR) spectrum through the Sunyaev-Zel'dovich effect. In this paper, we compute the amplitude of these distortions in various cosmological scenarios using the results of hydrodynamical simulations combined with analytic theory. For reionized cold dark matter (CDM) with h = 0.5 probed with the OVRO experiment (Theta approximately = 0.1 deg), we find that the amplitude of these fluctuations is (Delta T/T)(sub rms) = 1 x 10(exp -5) (Omega(sub i)/0.06) if the experiment looks at a random part of the sky and 6 x 10(exp -6)(Omega(sub i)/(0.06) if bright areas are avoided. Here Omega is the density of ionized baryons in units of the critical density, rho(sub c) = 2.78 x 10(exp 11)h(exp 2)/cu Mpc. Primary fluctuations would generate (Delta T/T)(sub rms) approximately = 2 x 10(exp -6) for this model. These distortions could be a dominant source of CMBR anisotropics on small and intermediate angular scales. It is important to note that these signals are generated relatively recently, when nonlinear effects are improtant, and do not require early reionization. We also examine the contribution to anisotropies from the Doppler effect, in both the linear and nonlinear regimes. In this case, the bulk of the signal is generated before a redshift of 10, provided that the intercluster medium is ionized back to the surface of last scattering. On the smallest scales thermal effects are bigger, while, on larger scales the Doppler-induced fluctuations are greater with the exact boundary determined by the scenario. However, over a wide range of scales, the two signals are equal to within a factor of a few.

  2. Signal distortion from microelectrodes in clinical EEG acquisition systems

    NASA Astrophysics Data System (ADS)

    Stacey, William C.; Kellis, Spencer; Patel, Paras R.; Greger, Bradley; Butson, Christopher R.

    2012-10-01

    Many centers are now using high-density microelectrodes during traditional intracranial electroencephalography (iEEG) both for research and clinical purposes. These microelectrodes are FDA-approved and integrate into clinical EEG acquisition systems. However, the electrical characteristics of these electrodes are poorly described and clinical systems were not designed to use them; thus, it is possible that this shift into clinical practice could have unintended consequences. In this study, we characterized the impedance of over 100 commercial macro- and microelectrodes using electrochemical impedance spectroscopy (EIS) to determine how electrode properties could affect signal acquisition and interpretation. The EIS data were combined with the published specifications of several commercial EEG systems to design digital filters that mimic the behavior of the electrodes and amplifiers. These filters were used to analyze simulated brain signals that contain a mixture of characteristic features commonly observed in iEEG. Each output was then processed with several common quantitative EEG measurements. Our results show that traditional macroelectrodes had low impedances and produced negligible distortion of the original signal. Brain tissue and electrical wiring also had negligible filtering effects. However, microelectrode impedances were much higher and more variable than the macroelectrodes. When connected to clinical amplifiers, higher impedance electrodes produced considerable distortion of the signal at low frequencies (<60 Hz), which caused significant changes in amplitude, phase, variance and spectral band power. In contrast, there were only minimal changes to the signal content for frequencies above 100 Hz. In order to minimize distortion with microelectrodes, we determined that an acquisition system should have an input impedance of at least 1 GΩ, which is much higher than most clinical systems. These results show that it is critical to account for variations

  3. Minimizing distortion in truss structures via Tabu search

    NASA Technical Reports Server (NTRS)

    Kincaid, Rex K.

    1990-01-01

    The shape control of large flexible space structures is of great interest to structural designers. A related problem is to seek ways to minimize the need for active controls by careful design and construction of the space structure. A tetrahedral truss structure that is used to support a precision segmented reflector or antenna surface is considered. The structure has a hexagonal platform and is characterized by the number of rings of members in the truss. For simplicity it is assumed that a flat truss geometry exists. Hence, all structural members and ball joints are required to have the same nominal length and diameter, respectively. Inaccuracies in the length of member or diameters of joints may produce unacceptable levels of surface distortion and internal forces. In the case of a truss structure supporting an antenna, surface distortions may cause unacceptable gain loss or pointing errors. The focus is solely on surface distortion, however, internal forces may be treated in a similar manner. To test the Tabu search code for DSQRMS the appropriate influence matrices are used for a flat, two-ring tetrahedral reflector truss generated by Green and Haftka (1989). In this example there are 102 members (NMEMB) and 31 ball joints (NJOINT) of the same nominal length, respectively. Hence, all the members may be interchanged and all the joints may be interchanged. In addition, 19 positions on the surface of the truss (NNODES) were used to measure error influences. After a variety of experiments a set of good parameters was choosen for Tabu search. The sample size at each iteration is 10*NMEMB and the short term memory size is 40. In addition four pruning rules were used to accelerate the search..

  4. Segregation distortion and linkage analysis in eggplant (Solanum melongena L.).

    PubMed

    Barchi, Lorenzo; Lanteri, Sergio; Portis, Ezio; Stàgel, Anikò; Valè, Giampiero; Toppino, Laura; Rotino, Giuseppe Leonardo

    2010-10-01

    An anther-derived doubled haploid (DH) population and an F2 mapping population were developed from an intraspecific hybrid between the eggplant breeding lines 305E40 and 67/3. The former incorporates an introgressed segment from Solanum aethiopicum Gilo Group carrying the gene Rfo-sa1, which confers resistance to Fusarium oxysporum; the latter is a selection from an intraspecific cross involving two conventional eggplant varieties and lacks Rfo-sa1. Initially, 28 AFLP primer combinations (PCs) were applied to a sample of 93 F2 individuals and 93 DH individuals, from which 170 polymorphic AFLP fragments were identified. In the DH population, the segregation of 117 of these AFLPs as well as markers closely linked to Rfo-sa1 was substantially distorted, while in the F2 population, segregation distortion was restricted to just 10 markers, and thus the latter was chosen for map development. A set of 141 F2 individuals was genotyped with 73 AFLP PCs (generating 406 informative markers), 32 SSRs, 4 tomato RFLPs, and 3 CAPS markers linked to Rfo-sa1. This resulted in the assignment of 348 markers to 12 major linkage groups. The framework map covered 718.7 cM, comprising 238 markers (212 AFLPs, 22 SSRs, 1 RFLP, and the Rfo-sa1 CAPS). Marker order and inter-marker distances in this eggplant map were largely consistent with those reported in a recently published SSR-based map. From an eggplant breeding perspective, DH populations produced by anther culture appear to be subject to massive segregation distortion and thus may not be very efficient in capturing the full range of genetic variation present in the parental lines.

  5. Transmission ratio distortion results in asymmetric introgression in Louisiana Iris

    PubMed Central

    2010-01-01

    Background Linkage maps are useful tools for examining both the genetic architecture of quantitative traits and the evolution of reproductive incompatibilities. We describe the generation of two genetic maps using reciprocal interspecific backcross 1 (BC1) mapping populations from crosses between Iris brevicaulis and Iris fulva. These maps were constructed using expressed sequence tag (EST)- derived codominant microsatellite markers. Such a codominant marker system allowed for the ability to link the two reciprocal maps, and compare patterns of transmission ratio distortion observed between the two. Results Linkage mapping resulted in markers that coalesced into 21 linkage groups for each of the reciprocal backcross maps, presumably corresponding to the 21 haploid chromosomes of I. brevicaulis and I. fulva. The composite map was 1190.0-cM long, spanned 81% of the I. brevicaulis and I. fulva genomes, and had a mean density of 4.5 cM per locus. Transmission ratio distortion (TRD) was observed in 138 (48.5%) loci distributed in 19 of the 21 LGs in BCIB, BCIF, or both BC1 mapping populations. Of the distorted markers identified, I. fulva alleles were detected at consistently higher-than-expected frequencies in both mapping populations. Conclusions The observation that I. fulva alleles are overrepresented in both mapping populations suggests that I. fulva alleles are favored to introgress into I. brevicaulis genetic backgrounds, while I. brevicaulis alleles would tend to be prevented from introgressing into I. fulva. These data are consistent with the previously observed patterns of introgression in natural hybrid zones, where I. fulva alleles have been consistently shown to introgress across species boundaries. PMID:20298609

  6. Spline function approximation techniques for image geometric distortion representation. [for registration of multitemporal remote sensor imagery

    NASA Technical Reports Server (NTRS)

    Anuta, P. E.

    1975-01-01

    Least squares approximation techniques were developed for use in computer aided correction of spatial image distortions for registration of multitemporal remote sensor imagery. Polynomials were first used to define image distortion over the entire two dimensional image space. Spline functions were then investigated to determine if the combination of lower order polynomials could approximate a higher order distortion with less computational difficulty. Algorithms for generating approximating functions were developed and applied to the description of image distortion in aircraft multispectral scanner imagery. Other applications of the techniques were suggested for earth resources data processing areas other than geometric distortion representation.

  7. Effect of spatial inlet temperature and pressure distortion on turbofan engine stability

    NASA Technical Reports Server (NTRS)

    Mehalic, Charles M.

    1988-01-01

    The effects of circumferential and radial inlet temperature distortion, circumferential pressure distortion, and combined temperature and pressure distortion on the stability of an advanced turbofan engine were investigated experimentally at simulated altitude conditions. With circumferential and radial inlet temperature distortion, a flow instability generated by the fan operating near stall caused the high-pressure compressor to surge at, or near, the same time as the fan. The effect of combined distortion was dependent on the relative location of the high-temperature and low-pressure regions; high-pressure compressor stalls occurred when the regions coincided, and fan stalls occurred with the regions separated.

  8. Pulse distortion in single-mode fibers. Part 2.

    PubMed

    Marcuse, D

    1981-09-01

    The theory of pulse distortion in single-mode fibers is extended to include laser sources such as injection lasers operating simultaneously at several distinct wavelengths. The transmitted pulse is expressed as a Fourier integral whose spectral function is given by an analytical expression in closed form. The rms width of the transmitted pulse is also expressed in closed form. Numerical examples illustrate the influence of the spectral width of the source and of its asymmetry on the shape and rms width of the pulse.

  9. Pathophysiological distortions in time perception and timed performance

    PubMed Central

    Allman, Melissa J.

    2012-01-01

    Distortions in time perception and timed performance are presented by a number of different neurological and psychiatric conditions (e.g. Parkinson's disease, schizophrenia, attention deficit hyperactivity disorder and autism). As a consequence, the primary focus of this review is on factors that define or produce systematic changes in the attention, clock, memory and decision stages of temporal processing as originally defined by Scalar Expectancy Theory. These findings are used to evaluate the Striatal Beat Frequency Theory, which is a neurobiological model of interval timing based upon the coincidence detection of oscillatory processes in corticostriatal circuits that can be mapped onto the stages of information processing proposed by Scalar Timing Theory. PMID:21921020

  10. Disformal coupling, CMB spectral distortion and distance duality relation.

    NASA Astrophysics Data System (ADS)

    Gubitosi, G.

    Light scalar fields can naturally couple disformally to Standard Model fields without giving rise to the unacceptably large fifth forces usually associated with light scalars. We show that these scalar fields can be studied and constrained through their interaction with photons, and focus particularly on changes to the Cosmic Microwave Background spectral distortions and violations of the distance duality relation. We then specialise our constraints to scalars which could play the role of axionic quintessence. The work here presented was done in collaboration with P. Brax, C. Burrage and A. C. Davis.

  11. Correction of atmospheric distortion with an image-sharpening telescope

    NASA Technical Reports Server (NTRS)

    Buffington, A.; Crawford, F. S.; Muller, R. A.; Schwemin, A. J.; Smits, R. G.

    1977-01-01

    A 30 x 5 cm aperture telescope employing six movable mirrors to compensate for atmospherically induced phase distortion is built and tested. A feedback system adjusts the mirrors in real time to maximize the intensity of light passing through a narrow slit in the image plane. Essentially diffraction-limited performance is achieved when imaging both laser and white-light objects through 250 m of turbulent atmosphere. The behavior of the telescope is accurately predicted by computer simulations. The system has yet to achieve its full potential, but has already operated successfully for objects as dim as 5th magnitude.

  12. One dimensional wavefront distortion sensor comprising a lens array system

    DOEpatents

    Neal, D.R.; Michie, R.B.

    1996-02-20

    A 1-dimensional sensor for measuring wavefront distortion of a light beam as a function of time and spatial position includes a lens system which incorporates a linear array of lenses, and a detector system which incorporates a linear array of light detectors positioned from the lens system so that light passing through any of the lenses is focused on at least one of the light detectors. The 1-dimensional sensor determines the slope of the wavefront by location of the detectors illuminated by the light. The 1 dimensional sensor has much greater bandwidth that 2 dimensional systems. 8 figs.

  13. One dimensional wavefront distortion sensor comprising a lens array system

    DOEpatents

    Neal, Daniel R.; Michie, Robert B.

    1996-01-01

    A 1-dimensional sensor for measuring wavefront distortion of a light beam as a function of time and spatial position includes a lens system which incorporates a linear array of lenses, and a detector system which incorporates a linear array of light detectors positioned from the lens system so that light passing through any of the lenses is focused on at least one of the light detectors. The 1-dimensional sensor determines the slope of the wavefront by location of the detectors illuminated by the light. The 1 dimensional sensor has much greater bandwidth that 2 dimensional systems.

  14. Optical distortions in electron/positron storage rings

    SciTech Connect

    Brown, K.L.; Donald, M.; Servranckx, R.

    1983-01-01

    We have studied the optical distortions in the PEP electron/positron storage ring for various optical configurations using the computer programs DIMAT, HARMON, PATRICIA, and TURTLE. The results are shown graphically by tracing several thousand trajectories from one interaction region to the next using TURTLE and by tracing a few selected rays several hundred turns using the programs DIMAT and PATRICIA. The results show an interesting correlation between the calculated optical cleanliness of a particular lattice configuration and the observed operating characteristics of the machine.

  15. Compensation of pulse-distortion in saturated laser amplifiers.

    PubMed

    Schimpf, Damian N; Ruchert, Clemens; Nodop, Dirk; Limpert, Jens; Tünnermann, Andreas; Salin, Francois

    2008-10-27

    We derive an expression describing pre-compensation of pulse-distortion due to saturation effects in short pulse laser-amplifiers. The analytical solution determines the optimum input pulse-shape required to obtain any arbitrary target pulse-shape at the output of the saturated laser-amplifier. The relation is experimentally verified using an all-fiber amplifier chain that is seeded by a directly modulated laser-diode. The method will prove useful in applications of high power, high energy laser-amplifier systems that need particular pulse-shapes to be efficient, e.g. micromachining and scientific laser-matter-interactions. PMID:18958044

  16. Genome sequence of vanilla distortion mosaic virus infecting Coriandrum sativum.

    PubMed

    Adams, I P; Rai, S; Deka, M; Harju, V; Hodges, T; Hayward, G; Skelton, A; Fox, A; Boonham, N

    2014-12-01

    The 9573-nucleotide genome of a potyvirus was sequenced from a Coriandrum sativum plant from India with viral symptoms. On analysis, this virus was shown to have greater than 85 % nucleotide sequence identity to vanilla distortion mosaic virus (VDMV). Analysis of the putative coat protein sequence confirmed that this virus was in fact VDMV, with greater than 91 % amino acid sequence identity. The genome appears to encode a 3083-amino-acid polyprotein potentially cleaved into the 10 mature proteins expected in potyviruses. Phylogenetic analysis confirmed that VDMV is a distinct but ungrouped member of the genus Potyvirus. PMID:25252813

  17. Genome sequence of vanilla distortion mosaic virus infecting Coriandrum sativum.

    PubMed

    Adams, I P; Rai, S; Deka, M; Harju, V; Hodges, T; Hayward, G; Skelton, A; Fox, A; Boonham, N

    2014-12-01

    The 9573-nucleotide genome of a potyvirus was sequenced from a Coriandrum sativum plant from India with viral symptoms. On analysis, this virus was shown to have greater than 85 % nucleotide sequence identity to vanilla distortion mosaic virus (VDMV). Analysis of the putative coat protein sequence confirmed that this virus was in fact VDMV, with greater than 91 % amino acid sequence identity. The genome appears to encode a 3083-amino-acid polyprotein potentially cleaved into the 10 mature proteins expected in potyviruses. Phylogenetic analysis confirmed that VDMV is a distinct but ungrouped member of the genus Potyvirus.

  18. Magnetic anisotropy and lattice distortions in the doped perovskite manganites

    SciTech Connect

    Suzuki, Y.; Hwang, H.Y.; Cheong, S.W.; Dover, R.B. van; Asamitsu, A.; Tokura, Y.

    1998-12-31

    The authors have investigated the magnetic anisotropies of doped manganite materials in epitaxial thin film and single crystal form. Structural characterization, including x-ray diffraction, Rutherford backscattering spectroscopy and atomic force microscopy, indicate that the epitaxial films are single crystalline and have excellent crystallinity. Since lattice distortions greatly affect the magnetic and transport properties of this family of materials, it is not surprising to find the profound effect of strain in films due to the lattice mismatch between the substrate and film. Magnetic anisotropy results of single crystals, subject to no external stress, is compared to those of epitaxial films.

  19. Luminosity Optimization With Offset, Crossing Angle, and Distortion

    SciTech Connect

    Wu, Juhao; Raubenheimer, T.O.; /SLAC

    2005-06-15

    In a linear collider, sources of beam jitter due to kicker noise, quadrupole vibration and long-range transverse wakefields will lead to beam offsets and tilts at the Intersection Point (IP). In addition, sources of emittance dilution such as short-range transverse wakefields or dispersive errors will lead to internal beam distortions. When the IP disruption parameter is large, these beam imperfections will be amplified by a single bunch kink instability which will lead to luminosity loss. In this paper, we study the luminosity loss and then the optimization required to partially cancel the luminosity loss both analytically and with direct simulation.

  20. Wind profile estimation from point to point laser distortion data

    NASA Technical Reports Server (NTRS)

    Leland, Robert

    1989-01-01

    The author's results on the problem of using laser distortion data to estimate the wind profile along the path of the beam are presented. A new model for the dynamics of the index of refraction in a non-constant wind is developed. The model agrees qualitatively with theoretical predictions for the index of refraction statistics in linear wind shear, and is approximated by the predictions of Taylor's hypothesis in constant wind. A framework for a potential in-flight experiment is presented, and the estimation problem is discussed in a maximum likelihood context.

  1. Probing correlations of early magnetic fields using μ-distortion

    SciTech Connect

    Ganc, Jonathan; Sloth, Martin S. E-mail: sloth@cp3.dias.sdu.dk

    2014-08-01

    The damping of a non-uniform magnetic field between the redshifts of about 10{sup 4} and 10{sup 6} injects energy into the photon-baryon plasma and causes the CMB to deviate from a perfect blackbody spectrum, producing a so-called μ-distortion. We can calculate the correlation (μ T) of this distortion with the temperature anisotropy T of the CMB to search for a correlation ( B{sup 2}ζ) between the magnetic field B and the curvature perturbation ζ; knowing the ( B{sup 2}ζ) correlation would help us distinguish between different models of magnetogenesis. Since the perturbations which produce the μ-distortion will be much smaller scale than the relevant density perturbations, the observation of this correlation is sensitive to the squeezed limit of ( B{sup 2}ζ), which is naturally parameterized by b{sub NL} (a parameter defined analogously to f{sub NL}). We find that a PIXIE-like CMB experiments has a signal to noise S/N≈ 1.0 × b{sub NL} ( B-tilde {sub μ}/10nG){sup 2}, where B-tilde {sub μ} is the magnetic field's strength on μ-distortion scales normalized to today's redshift; thus, a 10 nG field would be detectable with b{sub NL}=O(1). However, if the field is of inflationary origin, we generically expect it to be accompanied by a curvature bispectrum (ζ{sup 3}) induced by the magnetic field. For sufficiently small magnetic fields, the signal ( B{sup 2} ζ) will dominate, but for B-tilde {sub μ}∼> 1 nG, one would have to consider the specifics of the inflationary magnetogenesis model. We also discuss the potential post-magnetogenesis sources of a ( B{sup 2}ζ) correlation and explain why there will be no contribution from the evolution of the magnetic field in response to the curvature perturbation.

  2. On modeling center of foot pressure distortion through a medium.

    PubMed

    Betker, Aimee L; Moussavi, Zahra M K; Szturm, Tony

    2005-03-01

    The center of foot pressure (COP) is a commonly used output measure of the postural control system as it is indicative of the systems stability. A dense piece of foam, i.e., a sponge, can be used to emulate random environmental conditions that distort the ground reaction forces received and interpreted by the cutaneous sensors in the feet; thus introducing uncertainty into the control system. In this paper, the density and size of the sponge was selected such that a subject's weight did not cause full compression. In general, the COP is measured from the bottom of the sponge. As the sponge is used to distort ground reaction forces, it is reasonable then to assume that the COP signal would also be distorted. The use of other sensory information to identify state of balance, and compute necessary balance adjustments, is therefore required. In addition to a sponge, many different types of specialized footwear and inserts are used for people with peripheral neuropathy, such as diabetics. However, it is difficult to design diabetic footwear without a better understanding of the mechanical and physiological effects that different surfaces typical of outdoor terrains, such as a sponge, which cannot be predicted without the sense of the foot, have on balance. Therefore, the goal of this study was to investigate the change of the COP signal from the top and bottom of the sponge. Portable force sensing mats from Vista Medical were used to obtain the COP from the top and bottom of the sponge. The COP measured on the bottom of the sponge is not the same as the COP measured on the top, particularly in the medial-lateral direction. Several linear and nonlinear models were used to identify the unknown plant; i.e., the sponge. Overall, the nonlinear neural network method had superior performance when compared with the linear models. Thus, the results indicate that the signals from the top and bottom of the sponge are in fact different, and furthermore, they are nonlinearly related

  3. Spacetimes with vector distortion: Inflation from generalised Weyl geometry

    NASA Astrophysics Data System (ADS)

    Beltrán Jiménez, Jose; Koivisto, Tomi S.

    2016-05-01

    Spacetime with general linear vector distortion is introduced. Thus, the torsion and the nonmetricity of the affine connection are assumed to be proportional to a vector field (and not its derivatives). The resulting two-parameter family of non-Riemannian geometries generalises the conformal Weyl geometry and some other interesting special cases. Taking into account the leading nonlinear correction to the Einstein-Hilbert action results uniquely in the one-parameter extension of the Starobinsky inflation known as the alpha-attractor. The most general quadratic curvature action introduces, in addition to the canonical vector kinetic term, novel ghost-free vector-tensor interactions.

  4. Electron Beam Transport in Advanced Plasma Wave Accelerators

    SciTech Connect

    Williams, Ronald L

    2013-01-31

    The primary goal of this grant was to develop a diagnostic for relativistic plasma wave accelerators based on injecting a low energy electron beam (5-50keV) perpendicular to the plasma wave and observing the distortion of the electron beam's cross section due to the plasma wave's electrostatic fields. The amount of distortion would be proportional to the plasma wave amplitude, and is the basis for the diagnostic. The beat-wave scheme for producing plasma waves, using two CO2 laser beam, was modeled using a leap-frog integration scheme to solve the equations of motion. Single electron trajectories and corresponding phase space diagrams were generated in order to study and understand the details of the interaction dynamics. The electron beam was simulated by combining thousands of single electrons, whose initial positions and momenta were selected by random number generators. The model was extended by including the interactions of the electrons with the CO2 laser fields of the beat wave, superimposed with the plasma wave fields. The results of the model were used to guide the design and construction of a small laboratory experiment that may be used to test the diagnostic idea.

  5. Characterization, prediction, and correction of geometric distortion in 3 T MR images.

    PubMed

    Baldwin, Lesley N; Wachowicz, Keith; Thomas, Steven D; Rivest, Ryan; Fallone, B Gino

    2007-02-01

    The work presented herein describes our methods and results for predicting, measuring and correcting geometric distortions in a 3 T clinical magnetic resonance (MR) scanner for the purpose of image guidance in radiation treatment planning. Geometric inaccuracies due to both inhomogeneities in the background field and nonlinearities in the applied gradients were easily visualized on the MR images of a regularly structured three-dimensional (3D) grid phantom. From a computed tomography scan, the locations of just under 10 000 control points within the phantom were accurately determined in three dimensions using a MATLAB-based computer program. MR distortion was then determined by measuring the corresponding locations of the control points when the phantom was imaged using the MR scanner. Using a reversed gradient method, distortions due to gradient nonlinearities were separated from distortions due to inhomogeneities in the background B0 field. Because the various sources of machine-related distortions can be individually characterized, distortions present in other imaging sequences (for which 3D distortion cannot accurately be measured using phantom methods) can be predicted negating the need for individual distortion calculation for a variety of other imaging sequences. Distortions were found to be primarily caused by gradient nonlinearities and maximum image distortions were reported to be less than those previously found by other researchers at 1.5 T. Finally, the image slices were corrected for distortion in order to provide geometrically accurate phantom images. PMID:17388155

  6. Cortical processing of degraded speech sounds: effects of distortion type and continuity.

    PubMed

    Miettinen, Ismo; Alku, Paavo; Yrttiaho, Santeri; May, Patrick J C; Tiitinen, Hannu

    2012-04-01

    Human speech perception is highly resilient to acoustic distortions. In addition to distortions from external sound sources, degradation of the acoustic structure of the sound itself can substantially reduce the intelligibility of speech. The degradation of the internal structure of speech happens, for example, when the digital representation of the signal is impoverished by reducing its amplitude resolution. Further, the perception of speech is also influenced by whether the distortion is transient, coinciding with speech, or is heard continuously in the background. However, the complex effects of the acoustic structure and continuity of the distortion on the cortical processing of degraded speech are unclear. In the present magnetoencephalography study, we investigated how the cortical processing of degraded speech sounds as measured through the auditory N1m response is affected by variation of both the distortion type (internal, external) and the continuity of distortion (transient, continuous). We found that when the distortion was continuous, the N1m was significantly delayed, regardless of the type of distortion. The N1m amplitude, in turn, was affected only when speech sounds were degraded with transient internal distortion, which resulted in larger response amplitudes. The results suggest that external and internal distortions of speech result in divergent patterns of activity in the auditory cortex, and that the effects are modulated by the temporal continuity of the distortion.

  7. The nonlinear equatorial Kelvin wave. [in coastal currents of El Nino and Gulf of Guinea

    NASA Technical Reports Server (NTRS)

    Boyd, J. P.

    1980-01-01

    Using the method of strained coordinates, a uniformly valid approximation to the nonlinear equatorial Kelvin wave is derived. It is shown that nonlinear effects are negligible for the Kelvin waves associated with the Gulf of Guinea upwelling. The Kelvin waves involved in El Nino, however, are significantly distorted both in shape and speed. The leading edge is smoothed and expanded rather than steepened, but the trailing edge will form sharp fronts and eventually break.

  8. The role of numeracy and approximate number system acuity in predicting value and probability distortion.

    PubMed

    Patalano, Andrea L; Saltiel, Jason R; Machlin, Laura; Barth, Hilary

    2015-12-01

    It is well documented that individuals distort outcome values and probabilities when making choices from descriptions, and there is evidence of systematic individual differences in distortion. In the present study, we investigated the relationship between individual differences in such distortions and two measures of numerical competence, numeracy and approximate number system (ANS) acuity. Participants indicated certainty equivalents for a series of simple monetary gambles, and data were used to estimate individual-level value and probability distortion, using a cumulative prospect theory framework. We found moderately strong negative correlations between numeracy and value and probability distortion, but only weak and non-statistically reliable correlations between ANS acuity and distortions. We conclude that low numeracy contributes to number distortion in decision making, but that approximate number system acuity might not underlie this relationship.

  9. Effects of inflow distortion profiles on fan tone noise calculated using a 3-D theory

    NASA Technical Reports Server (NTRS)

    Kobayashi, H.; Groeneweg, J. F.

    1979-01-01

    Calculations of the fan tone acoustic power and modal structure generated by complex distortions in axial inflow velocity are presented. The model used treats the motor as a rotating three-dimensional cascade and calculates the acoustic field from the distortion-produced dipole distribution on the blades including noncompact source effects. Radial and circumferential distortion shapes are synthesized from Fourier-Bessel components representing individual distortion modes. The relation between individual distortion modes and the generated acoustic modes is examined for particular distortion cases. Comparisons between theoretical and experimental results for distortions produced by wakes from upstream radial rods show that the analysis is a good predictor of acoustic power dependence on disturbance strength.

  10. A New Distortion Solution for NIRC2 on the Keck II Telescope

    NASA Astrophysics Data System (ADS)

    Service, M.; Lu, J. R.; Campbell, R.; Sitarski, B. N.; Ghez, A. M.; Anderson, J.

    2016-09-01

    We present a new geometric distortion model for the narrow-field mode of the near-infrared camera (NIRC2) fed by the adaptive optics system on the W. M. Keck II telescope. The adaptive optics system and NIRC2 camera were realigned on 2015 April 13. Observations of the crowded globular cluster, M53, were obtained before and after the realignment to characterize the geometric field distortion. The distorted NIRC2 positions of M53 stars were compared with precise astrometry of this cluster from Hubble Space Telescope observations. The resulting distortion map constructed just before the realignment is consistent with the previous solution derived using data from 2007 to 2009, indicating that the distortion has been stable to ∼0.5 mas. The distortion map changed significantly after a realignment of 4.5 mas (75%) rms, and the new distortion model for post-realignment observations have a total accuracy of ∼1.1 mas.

  11. Bayesian redshift-space distortions correction from galaxy redshift surveys

    NASA Astrophysics Data System (ADS)

    Kitaura, Francisco-Shu; Ata, Metin; Angulo, Raul E.; Chuang, Chia-Hsun; Rodríguez-Torres, Sergio; Monteagudo, Carlos Hernández; Prada, Francisco; Yepes, Gustavo

    2016-03-01

    We present a Bayesian reconstruction method which maps a galaxy distribution from redshift- to real-space inferring the distances of the individual galaxies. The method is based on sampling density fields assuming a lognormal prior with a likelihood modelling non-linear stochastic bias. Coherent redshift-space distortions are corrected in a Gibbs-sampling procedure by moving the galaxies from redshift- to real-space according to the peculiar motions derived from the recovered density field using linear theory. The virialized distortions are corrected by sampling candidate real-space positions along the line of sight, which are compatible with the bulk flow corrected redshift-space position adding a random dispersion term in high-density collapsed regions (defined by the eigenvalues of the Hessian). This approach presents an alternative method to estimate the distances to galaxies using the three-dimensional spatial information, and assuming isotropy. Hence the number of applications is very broad. In this work, we show the potential of this method to constrain the growth rate up to k ˜ 0.3 h Mpc-1. Furthermore it could be useful to correct for photometric redshift errors, and to obtain improved baryon acoustic oscillations (BAO) reconstructions.

  12. Motion and distortion correction of skeletal muscle echo planar images.

    PubMed

    Davis, Andrew D; Noseworthy, Michael D

    2016-07-01

    This paper examines two artifacts facing researchers who use gradient echo (GRE) echo planar imaging (EPI) for time series studies of skeletal muscles in limbs. The first is through-plane blood flow during the acquisition, causing a vessel motion artifact that inhibits proper motion correction of the data. The second is distortion of EPI images caused by B0 field inhomogeneities. Though software tools are available for correcting these artifacts in brain EPI images, the tools do not perform well on muscle images. The severity of the two artifacts was described using image similarity measures, and the data was processed with both a conventional motion correction program and custom written tools. The conventional program did not perform well on the limb images, in fact significantly degrading image quality in some trials. Data is presented which proves that arterial pulsatile signal caused the impairment in motion correction. The new tools were shown to perform much better, achieving substantial motion correction and distortion correction of the muscle EPI images. PMID:26972774

  13. The magnetic-distortion probe: Velocimetry in conducting fluids

    NASA Astrophysics Data System (ADS)

    Miralles, Sophie; Verhille, Gautier; Plihon, Nicolas; Pinton, Jean-François

    2011-09-01

    A new type of velocimeter, capable of local velocity measurements in conducting fluids, is introduced. The principle of the "magnetic-distortion probe" is based on the measurement of the induced magnetic field by the flow of a conducting fluid in the vicinity of a localized magnetic field. The new velocimeter has no moving parts, and can be enclosed in a sealed cap, easing the implementation in harsh environments, such as liquid metals. The proposed method allows one to probe both the continuous part and fluctuations of the velocity, the temporal and spatial resolution being linked to the actual geometric configuration of the probe. A prototype probe has been tested in a gallinstan pipe flow and in a fully turbulent flow of liquid gallium generated by the counter rotation of two coaxial impellers in a cylinder. The signals have been compared to a reference potential probe and show very good agreement both for time-averaged velocities and turbulent fluctuations. The prototype is shown to detect motion from a few cm s-1 to a few m s-1. Moreover, the use of the magnetic-distortion probe with large-scale applied magnetic field is discussed.

  14. Task 7: Endwall treatment inlet flow distortion analysis

    NASA Technical Reports Server (NTRS)

    Hall, E. J.; Topp, D. A.; Heidegger, N. J.; McNulty, G. S.; Weber, K. F.; Delaney, R. A.

    1996-01-01

    The overall objective of this study was to develop a 3-D numerical analysis for compressor casing treatment flowfields, and to perform a series of detailed numerical predictions to assess the effectiveness of various endwall treatments for enhancing the efficiency and stall margin of modern high speed fan rotors. Particular attention was given to examining the effectiveness of endwall treatments to counter the undesirable effects of inflow distortion. Calculations were performed using three different gridding techniques based on the type of casing treatment being tested and the level of complexity desired in the analysis. In each case, the casing treatment itself is modeled as a discrete object in the overall analysis, and the flow through the casing treatment is determined as part of the solution. A series of calculations were performed for both treated and untreated modern fan rotors both with and without inflow distortion. The effectiveness of the various treatments were quantified, and several physical mechanisms by which the effectiveness of endwall treatments is achieved are discussed.

  15. Difficulties distinguishing dark energy from modified gravity via redshift distortions

    SciTech Connect

    Simpson, Fergus; Peacock, John A.

    2010-02-15

    The bulk motion of galaxies induced by the growth of cosmic structure offers a rare opportunity to test the validity of general relativity across cosmological scales. However, modified gravity can be degenerate in its effect with the unknown values of cosmological parameters. More seriously, even the 'observed' value of the redshift-space distortions used to measure the fluctuation growth rate depends on the assumed cosmological parameters (the Alcock-Paczynski effect). We give a full analysis of these issues, showing how to combine redshift-space distortions with baryon acoustic oscillations and CMB data, in order to obtain joint constraints on deviations from general relativity and on the equation of state of dark energy while allowing for factors such as nonzero curvature. In particular we note that the evolution of {Omega}{sub m}(z), along with the Alcock-Paczynski effect, produces a degeneracy between the equation of state w and the modified growth parameter {gamma}. Typically, the total marginalized error on either of these parameters will be larger by a factor {approx_equal}2 compared to the conditional error where one or the other is held fixed. We argue that future missions should be judged by their figure of merit as defined in the w{sub p}-{gamma} plane, and note that the inclusion of spatial curvature can degrade this value by an order of magnitude.

  16. Giant orthorhombic distortions by Cu+ in ferrimagnetic spinel Mn334

    NASA Astrophysics Data System (ADS)

    Chung, Jae-Ho; Lee, Kee Hwan; Chang, Hun; Hwang, In Yong; Kang, Hyun Wook; Kim, Su Jae; Lee, Seongsu

    2015-03-01

    Mn3O4 is a tetragonal (c > a) spinel that exhibits noncollinear Yafet-Kittel ferrimagnetic ordering at low temperatures. We report large orthorhombic distortions in its ferrimagnetic phase stabilized by a few percent of Cu doping. The orthorhombic strains of the ferrimagnetic phases increased linearly to the doping and reached up to ɛ ~ 8 . 2 ×10-3 for x = 0.19, which is three times larger than the saturated value under external magnetic fields. For high doping (xagt 0 . 17), the distortions first appeared in the paramagnetic phases and underwent further enhancement simultaneously with the onset of the noncollinear ferrimagnetic ordering. We present the rich magnetostructural phase diagram of CuxMn3-xO4, and argue that the diluted t2 orbital degeneracy of Cu2+ under tetrahedral crystal field breaks the global symmetry and triggers the orthorhombic instability inherent in Mn3O4. This work was supported by the National Research Foundation of Korea through the ARCNEX (NRF-2011-0031933).

  17. Minimum-distortion isometric shape correspondence using EM algorithm.

    PubMed

    Sahillioğlu, Yusuf; Yemez, Yücel

    2012-11-01

    We present a purely isometric method that establishes 3D correspondence between two (nearly) isometric shapes. Our method evenly samples high-curvature vertices from the given mesh representations, and then seeks an injective mapping from one vertex set to the other that minimizes the isometric distortion. We formulate the problem of shape correspondence as combinatorial optimization over the domain of all possible mappings, which then reduces in a probabilistic setting to a log-likelihood maximization problem that we solve via the Expectation-Maximization (EM) algorithm. The EM algorithm is initialized in the spectral domain by transforming the sampled vertices via classical Multidimensional Scaling (MDS). Minimization of the isometric distortion, and hence maximization of the log-likelihood function, is then achieved in the original 3D euclidean space, for each iteration of the EM algorithm, in two steps: by first using bipartite perfect matching, and then a greedy optimization algorithm. The optimal mapping obtained at convergence can be one-to-one or many-to-one upon choice. We demonstrate the performance of our method on various isometric (or nearly isometric) pairs of shapes for some of which the ground-truth correspondence is available.

  18. Phase transitions and separations in a distorted liquid crystalline mixture.

    PubMed

    Kasch, Nicholas; Dierking, Ingo

    2015-08-14

    A theoretical method is proposed for modelling phase transitions and phase ranges in a multi-component liquid crystalline mixture where the liquid crystal structure is distorted and defects are formed. This method employs the Maier-Saupe and Kobayashi-McMillan theories of liquid crystalline ordering and the Flory-Huggins theory of mixtures. It builds on previous work on mixed systems that can form smectic-A and nematic phases by incorporating "distortion factors" into the expression for the local free energy of the mixture, which account for the effects of a deviation of the liquid crystal structure from the uniform nematic and smectic-A states. The method allows a simple description of chiral defect phases such as the blue phase and the twist grain boundary phase. In a previous work, it was shown that a model of the blue phase along these lines could effectively explain the observed effect whereby an added guest compound can stabilize the phase by separating into the high energy defect regions of the structure. It is shown here that with the correct choice of guest material a similar effect could be observed for the twist grain boundary phase.

  19. Phase transitions and separations in a distorted liquid crystalline mixture

    NASA Astrophysics Data System (ADS)

    Kasch, Nicholas; Dierking, Ingo

    2015-08-01

    A theoretical method is proposed for modelling phase transitions and phase ranges in a multi-component liquid crystalline mixture where the liquid crystal structure is distorted and defects are formed. This method employs the Maier-Saupe and Kobayashi-McMillan theories of liquid crystalline ordering and the Flory-Huggins theory of mixtures. It builds on previous work on mixed systems that can form smectic-A and nematic phases by incorporating "distortion factors" into the expression for the local free energy of the mixture, which account for the effects of a deviation of the liquid crystal structure from the uniform nematic and smectic-A states. The method allows a simple description of chiral defect phases such as the blue phase and the twist grain boundary phase. In a previous work, it was shown that a model of the blue phase along these lines could effectively explain the observed effect whereby an added guest compound can stabilize the phase by separating into the high energy defect regions of the structure. It is shown here that with the correct choice of guest material a similar effect could be observed for the twist grain boundary phase.

  20. Distortion and regulation characterization of a Mapham inverter

    NASA Technical Reports Server (NTRS)

    Sundberg, Richard C.; Brush, Andrew S.; Button, Robert M.; Patterson, Alexander G.

    1989-01-01

    Output voltage Total Harmonic Distortion (THD) of a 20kHz, 6kVA Mapham resonant inverter is characterized as a function of its switching-to-resonant frequency ratio, f sub s/f sub r, using the EASY5 engineering analysis system. EASY5 circuit simulation results are compared with hardware test results to verify the accuracy of the simulations. The effects of load on the THD versus f sub s/f sub r ratio is investigated for resistive, leading, and lagging power factor load impedances. The effect of the series output capacitor on the Mapham inverter output voltage distortion and inherent load regulation is characterized under loads of various power factors and magnitudes. An optimum series capacitor value which improves the inherent load regulation to better than 3 percent is identified. The optimum series capacitor value is different than the value predicted from a modeled frequency domain analysis. An explanation is proposed which takes into account the conduction overlap in the inductor pairs during steady-state inverter operation, which decreases the effective inductance of a Mapham inverter. A fault protection and current limit method is discussed which allows the Mapham inverter to operate into a short circuit, even when the inverter resonant circuit becomes overdamped.

  1. High-informative version of nonlinear transformation of Langmuir waves to electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Erofeev, Vasily I.; Erofeev

    2014-04-01

    The concept of informativeness of nonlinear plasma physical scenario is discussed. Basic principles for heightening the informativeness of plasma kinetic models are explained. Former high-informative correlation analysis of plasma kinetics (Erofeev, V. 2011 High-Informative Plasma Theory, Saarbrücken: LAP) is generalized for studies of weakly turbulent plasmas that contain fields of solenoidal plasma waves apart from former potential ones. Respective machinery of plasma kinetic modeling is applied to an analysis of fusion of Langmuir waves with transformation to electromagnetic waves. It is shown that the customary version of this phenomenon (Terashima, Y. and Yajima, N. 1963 Prog. Theor. Phys. 30, 443; Akhiezer, I. A., Danelia, I. A. and Tsintsadze, N. L. 1964 Sov. Phys. JETP 19, 208; Al'tshul', L. M. and Karpman, V. I. 1965 Sov. Phys. JETP 20, 1043) substantially distorts the picture of merging of Langmuir waves with long wavelengths (λ >~ c/ωpe ).

  2. Mixing of blackbodies: entropy production and dissipation of sound waves in the early Universe

    NASA Astrophysics Data System (ADS)

    Khatri, R.; Sunyaev, R. A.; Chluba, J.

    2012-07-01

    Mixing of blackbodies with different temperatures creates a spectral distortion which, at lowest order, is a y-type distortion, indistinguishable from the thermal y-type distortion produced by the scattering of cosmic microwave background (CMB) photons by hot electrons residing in clusters of galaxies. This process occurs in the radiation-pressure dominated early Universe, when the primordial perturbations excite standing sound waves on entering the sound horizon. Photons from different phases of the sound waves, having different temperatures, diffuse through the electron-baryon plasma and mix together. This diffusion, with the length defined by Thomson scattering, dissipates sound waves and creates spectral distortions in the CMB. Of the total dissipated energy, 2/3 raises the average temperature of the blackbody part of spectrum, while 1/3 creates a distortion of y-type. It is well known that at redshifts 105 ≲ z ≲ 2 × 106, comptonization rapidly transforms y-distortions into a Bose-Einstein spectrum. The chemical potential of the Bose-Einstein spectrum is again 1/3 the value we would get if all the dissipated energy was injected into a blackbody spectrum but no extra photons were added. We study the mixing of blackbody spectra, emphasizing the thermodynamic point of view, and identifying spectral distortions with entropy creation. This allows us to obtain the main results connected with the dissipation of sound waves in the early Universe in a very simple way. We also show that mixing of blackbodies in general, and dissipation of sound waves in particular, leads to creation of entropy.

  3. Shock wave structure in heterogeneous reactive media

    SciTech Connect

    Baer, M.R.

    1997-06-01

    Continuum mixture theory and mesoscale modeling are applied to describe the behavior of shock-loaded heterogeneous media. One-dimensional simulations of gas-gun experiments demonstrate that the wave features are well described by mixture theory, including reflected wave behavior and conditions where significant reaction is initiated. Detailed wave fields are resolved in numerical simulations of impact on a lattice of discrete explosive {open_quotes}crystals{close_quotes}. It is shown that rapid distortion first occurs at material contact points; the nature of the dispersive fields includes large amplitude fluctuations of stress over several particle pathlengths. Localization of energy causes {open_quotes}hot-spots{close_quotes} due to shock focusing and plastic work as material flows into interstitial regions.

  4. Linear fitting interpolation based on FOV division for correcting wide angle fish-eye lens distortion

    NASA Astrophysics Data System (ADS)

    Li, An; Wu, Yi-si; Chen, Chi; Zheng, Zhen-rong

    2015-09-01

    The wide angle lens, like fish eye lens, suffers great optical distortion that causes severe deformation of the real world. A method to correct the strong distortion was presented in this work. Due to the nonlinear distribution of the distortion, linear algorithms are generally not under consideration to establish the math model of distorted-to-ideal images. However, this method employed the calibration pattern that comprised of regular array of dots to divides the full field of view (FOV) to subsections, each subsection is a small FOV, the mapping parameters between the distorted image and ideal image in each small FOV can be calculated by employing the very simple linear polynomial. Thus, applying the determined parameters to their corresponding sub-FOVs, respectively, all the ideal pixel coordinates of the distorted image can be obtained. The method employed linear polynomial characterizes the geometric deformation between the distorted and ideal images directly. Therefore, it contains both of radial distortion and tangential distortion and there is no need of concerning any intrinsic or extrinsic parameters of the optical systems. So, this algorithm reliefs the computational work that employed by conventional radial models and other mathematical models. Experiments performed on off-axis optical systems which exist complicated distortion, such as the head mounted displays (HMDs), had already yielded accurate correcting results. Likewise, in this paper, the experiments refer to the fish-eye lens also verify the effectiveness and flexibility of this method, as well, high correcting accuracy is achieved.

  5. Image distortion correction for micromanipulation system based on SLM microscopic vision.

    PubMed

    Wang, Yuezong; Jin, Yan; Wang, Lika

    2016-03-01

    Stereo light microscope (SLM) simulates stereo imaging principle of human eyes. Microscopic vision system based on SLM has become an important visual tool for micro measurement, micromanipulation, and microinjection. We develop a micromanipulation system based on SLM and present an image distortion correction method. We mainly correct two kinds of image distortions: lateral and vertical distortion. Distortion correction consists of two steps. First, a linear fitting algorithm for each row or column of target points is developed, and the fitting errors are calculated. If the fitting errors are smaller than a given threshold, the linear fitting results are kept and used. Otherwise polynomial fitting procedure will be used. Second, the parallelism of straight lines is corrected. The results show that a line in world coordinate frame (WCF) is not necessarily a straight line in image coordinate frame (ICF), or two parallel lines in WCF may be not parallel in ICF. Distortion correction can restore the parallel and linear relationship. For distorted left and right images, the magnitude of distortion exceeds 6 pixels and 4 pixels in the horizontal direction, and 1.2 pixels and 1.7 pixels in the vertical direction, respectively. After corrected, for left and right image, distortion can be reduced to 0.8 pixels and 0.7 pixels in the horizontal direction, and 0.96 pixels and 1.3 pixels in the vertical direction, respectively. The results show that distortion parameters obtained from the proposed method can effectively correct distorted images. PMID:26789139

  6. Modeling of Millimeter-Wave Modulation Characteristics of Semiconductor Lasers under Strong Optical Feedback

    PubMed Central

    Bakry, Ahmed

    2014-01-01

    This paper presents modeling and simulation on the characteristics of semiconductor laser modulated within a strong optical feedback (OFB-)induced photon-photon resonance over a passband of millimeter (mm) frequencies. Continuous wave (CW) operation of the laser under strong OFB is required to achieve the photon-photon resonance in the mm-wave band. The simulated time-domain characteristics of modulation include the waveforms of the intensity and frequency chirp as well as the associated distortions of the modulated mm-wave signal. The frequency domain characteristics include the intensity modulation (IM) and frequency modulation (FM) responses in addition to the associated relative intensity noise (RIN). The signal characteristics under modulations with both single and two mm-frequencies are considered. The harmonic distortion and the third order intermodulation distortion (IMD3) are examined and the spurious free dynamic range (SFDR) is calculated. PMID:25383381

  7. Spatial-temporal distortions and calibration of ultrashort pulses in complex optical systems

    NASA Astrophysics Data System (ADS)

    Liu, J.; Zhu, L. J.; Chang, S. Q.; Chen, A. Q.; Liu, S. Q.; Yuan, F.; Zhang, H. Y.; Zheng, Z. R.

    2016-07-01

    Ultrashort laser pulse has been widely used in various applications. Its parameters, such as the pulse duration and the spectral bandwidth, should be controlled accurately in order to achieve high spatial and temporal resolution, as well as high local field intensity. In this paper, we have proposed a method to trace the propagation of ultrashort pulses through optical systems, especially the complex optics. The approach, in which both the material's dispersion and optical aberrations are taken into consideration, is developed based on the geometrical ray-tracing combined with wave theories. This method is validated by simulating the propagation of a femtosecond pulse through a specific practical imaging system. As the numerical result shows that the spatial-temporal performances of pulses are influenced greatly by optical elements, the calibration arrangement is employed to compensate for those undesired distortions. The negative dispersion of the optical grisms (the combination of gratings and prisms) is utilized in the calibration process to offset the positive dispersion introduced by lenses. The final result shows effectiveness of the correction.

  8. Half-metallicity and tetragonal distortion in semi-Heusler alloy FeCrSe

    SciTech Connect

    Huang, H. M. Luo, S. J.; Yao, K. L.

    2014-01-28

    Full-potential linearized augmented plane wave methods are carried out to investigate the electronic structures and magnetic properties in semi-Heusler alloy FeCrSe. Results show that FeCrSe is half-metallic ferromagnet with the half-metallic gap 0.31 eV at equilibrium lattice constant. Calculated total magnetic moment of 2.00μ{sub B} per formula unit follows the Slater-Pauling rule quite well. Two kinds of structural changes are used to investigate the sensitivity of half-metallicity. It is found that the half-metallicity can be retained when lattice constant is changed by −4.56% to 3.52%, and the results of tetragonal distortion indicate the half-metallicity can be kept at the range of c/a ratio from 0.85 to 1.20. The Curie temperature, cohesive energy, and heat of formations of FeCrSe are also discussed.

  9. Anomalous Centrifugal Distortion in HDO and Spectroscopic Data Bases

    NASA Astrophysics Data System (ADS)

    Coudert, L. H.

    2015-06-01

    The HDO molecule is important from the atmospheric point of view as it can be used to study the water cycle in the earth atmosphere. It is also interesting from the spectroscopic point of view as it displays an anomalous centrifugal distortion similar to that of the normal species H_2O. A model developed to treat the anomalous distortion in HDO should account for the fact that it lacks a two-fold axis of symmetry. A new treatment aimed at the calculation of the rovibrational energy of the HDO molecule and allowing for anomalous centrifugal distortion effects has been developed. It is based on an effective Hamiltonian in which the large amplitude bending ν_2 mode and the overall rotation of the molecule are treated simultaneously. Due to the lack of a two-fold axis of symmetry, this effective Hamiltonian contains terms arising from the non-diagonal component of the inertia tensor and from the Coriolis-coupling between the large amplitude bending ν_2 mode and the overall rotation of the molecule. This new treatment has been used to perform a line position analysis of a large body of infrared, microwave, and hot water vapor data involving the ground and (010) states up to J=22. For these 4413 data, a unitless standard deviation of 1.1 was achieved. A line intensity analysis was also carried out and allowed us to reproduce the strength of 1316 transitions^c with a unitless standard deviation of 1.1. In the talk, the new theoretical approach will be presented. The results of both analyses will be discussed and compared with those of a previous investigation. The new spectroscopic data base built will be compared with HITRAN 2012. Herbin et al., Atmos. Chem. Phys.~9 (2009) 9433; and Schneider and Hase, Atmos. Chem. Phys.~ 11 (2011) 11207. Coudert, Wagner, Birk, Baranov, Lafferty, and Flaud, J. Molec. Spectrosc.~251 (2008) 339. Johns, J. Opt. Soc. Am. B~2 (1985) 1340 Toth, J. Molec. Spectrosc.~162 (1993) 20 Paso and Horneman, J. Opt. Soc. Am. B~12 (1995) 1813 Toth, J

  10. Testing cosmic geometry without dynamic distortions using voids

    SciTech Connect

    Hamaus, Nico; Sutter, P.M.; Lavaux, Guilhem; Wandelt, Benjamin D. E-mail: sutter@iap.fr E-mail: wandelt@iap.fr

    2014-12-01

    We propose a novel technique to probe the expansion history of the Universe based on the clustering statistics of cosmic voids. In particular, we compute their two-point statistics in redshift space on the basis of realistic mock galaxy catalogs and apply the Alcock-Paczynski test. In contrast to galaxies, we find void auto-correlations to be marginally affected by peculiar motions, providing a model-independent measure of cosmological parameters without systematics from redshift-space distortions. Because only galaxy-galaxy and void-galaxy correlations have been considered in these types of studies before, the presented method improves both statistical and systematic uncertainties on the product of angular diameter distance and Hubble rate, furnishing the potentially cleanest probe of cosmic geometry available to date.

  11. Pulse distortion in single-mode fibers. 3: Chirped pulses.

    PubMed

    Marcuse, D

    1981-10-15

    The theory of pulse distortion in single-mode fibers is extended to include laser sources that suffer a linear wavelength sweep (chirp) during the duration of the pulse. The transmitted pulse is expressed as a Fourier integral whose spectral function is given by an analytical expression in closed form. The rms width of the transmitted pulse is also expressed in closed form. Numerical examples illustrate the influence of the chirp on the shape and rms width of the pulse. A somewhat paradoxical situation exists. A given input pulse can be made arbitrarily short by a sufficiently large amount of chirping, and, after a given fiber length, this chirped pulse returns to its original width. But at this particular distance an unchirped pulse would be only [equiation] times longer. Thus chirping can improve the rate of data transmission by only 40%.

  12. Self-report distortions of puffing topography in daily smokers.

    PubMed

    Pulcu, Erdem

    2016-08-01

    Under-reporting tobacco consumption is common, although there is lack of evidence whether under-reporting is associated with health risk perception. In this study, smoking topography from 110 smokers was recorded over 24 hours, aiming to capture a representative average of smoking behaviour. Participants significantly under-reported the duration of secondary exposure, and there was a significant interaction between self-report distortion type and risk perception. Analysis showed that smokers under-reporting puff number declared perceiving significantly less susceptibility to acquiring airway diseases, which is correlating significantly with the level of under-reporting. The present findings may suggest that under-reporting smoking behaviour has psychological functions beyond achieving social desirability.

  13. Optimized 3D watermarking for minimal surface distortion.

    PubMed

    Bors, Adrian G; Luo, Ming

    2013-05-01

    This paper proposes a new approach to 3D watermarking by ensuring the optimal preservation of mesh surfaces. A new 3D surface preservation function metric is defined consisting of the distance of a vertex displaced by watermarking to the original surface, to the watermarked object surface as well as the actual vertex displacement. The proposed method is statistical, blind, and robust. Minimal surface distortion according to the proposed function metric is enforced during the statistical watermark embedding stage using Levenberg-Marquardt optimization method. A study of the watermark code crypto-security is provided for the proposed methodology. According to the experimental results, the proposed methodology has high robustness against the common mesh attacks while preserving the original object surface during watermarking.

  14. Evolution of nanoparticle-induced distortion on viral polyhedra.

    PubMed

    Das, Sumistha; Datta, Alokmay; Mukherjee, Smita; Biswas, Nupur; Goswami, Arunava

    2013-03-01

    Morphological changes in the polyhedra of the Bombyx mori L. nuclear polyhedrosis virus (BmNPV), a baculovirus causing the deadly grasserie disease in silkworms, brought about by mixing with lipophilically capped amorphous silica nanoparticles (LASN, average size 10 ± 2 nm) were studied with scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. SEM shows that the regular octagonal polyhedra facets are replaced by a larger number of newly formed irregular ones. The average number of facets reveals a nonlinear growth pattern with nanoparticle (NP) concentration, where an initial linear region ends in a plateau. IR bands corresponding to vibration modes of the capping show (a) a saturation of the area under the band with NP concentration, indicating a correlation with attachment to viral polyhedra and (b) a narrowing of the band per NP from the linear to the plateau portions of the distortion curve, suggesting non-equilibrium and equilibrium situations, respectively. PMID:23860867

  15. Distortion product otoacoustic emissions upon ear canal pressurization.

    PubMed

    Zebian, Makram; Schirkonyer, Volker; Hensel, Johannes; Vollbort, Sven; Fedtke, Thomas; Janssen, Thomas

    2013-04-01

    The purpose of this study was to quantify the change in distortion product otoacoustic emission (DPOAE) level upon ear canal pressurization. DPOAEs were measured on 12 normal-hearing human subjects for ear canal static pressures between -200 and +200 daPa in (50 ± 5) daPa steps. A clear dependence of DPOAE levels on the pressure was observed, with levels being highest at the maximum compliance of the middle ear, and decreasing on average by 2.3 dB per 50 daPa for lower and higher pressures. Ear canal pressurization can serve as a tool for improving the detectability of DPOAEs in the case of middle-ear dysfunction.

  16. Eliminating spatial distortions in Anger-type gamma cameras

    NASA Astrophysics Data System (ADS)

    Leitner, Michael; Ceeh, Hubert; Weber, Josef-Andreas

    2012-12-01

    A procedure to quantify and correct the spatial distortions inherent to Anger-type gamma cameras is presented. It consists in imaging a pattern of regularly spaced holes, assigning to each pair of lattice indices the actual position on the detector and generating a look-up matrix describing the inverse mapping. This allows one to correct the position of the distinct events either during or after the measurement with minimal computational effort. The corrected spectrum is indistinguishable from a spectrum taken with an ideal detector in a statistical sense. The effect of the increased resolution on measurements of angular correlation of positron annihilation radiation is demonstrated. The presented scheme is applicable for all types of area detectors.

  17. Phonon triggered rhombohedral lattice distortion in vanadium at high pressure.

    PubMed

    Antonangeli, Daniele; Farber, Daniel L; Bosak, Alexei; Aracne, Chantel M; Ruddle, David G; Krisch, Michael

    2016-01-01

    In spite of the simple body-centered-cubic crystal structure, the elements of group V, vanadium, niobium and tantalum, show strong interactions between the electronic properties and lattice dynamics. Further, these interactions can be tuned by external parameters, such as pressure and temperature. We used inelastic x-ray scattering to probe the phonon dispersion of single-crystalline vanadium as a function of pressure to 45 GPa. Our measurements show an anomalous high-pressure behavior of the transverse acoustic mode along the (100) direction and a softening of the elastic modulus C44 that triggers a rhombohedral lattice distortion occurring between 34 and 39 GPa. Our results provide the missing experimental confirmation of the theoretically predicted shear instability arising from the progressive intra-band nesting of the Fermi surface with increasing pressure, a scenario common to all transition metals of group V. PMID:27539662

  18. Biomechanics and functional distortion of the human mandible.

    PubMed

    Choi, Andy H; Conway, Richard C; Taraschi, Valerio; Ben-Nissan, Besim

    2015-11-01

    The reaction to the use of finite element analysis (FEA) in the study of the human body has been particularly enthusiastic. Of equal and challenging complexity is the investigation of load/stress distribution and morphological distortion of the human mandible under functional loads. Furthermore, the mandible also impacts directly on body function and esthetics, playing a vital role, such as mastication and speech. The application of FEA to the biomechanical investigation of the oral systems, such as human teeth and mandibular bone remodeling, began in the early 1970s. The clinical significance of jaw deformation is unknown. The primary concern is that deformation might result in an ill-fitting superstructure or the creation of harmful strains in the patient-implant complex. Although mandibular implant treatment has a high success rate, the possibility of failure caused by these dimensional changes and the related micromotion cannot be ignored.

  19. Distorted mass edges at LHC from supersymmetric leptoquarks

    NASA Astrophysics Data System (ADS)

    Reuter, Jürgen; Wiesler, Daniel

    2011-07-01

    Supersymmetric (SUSY) grand unified theories based on exceptional gauge groups such as E6 have recently triggered a lot of interest. Aside from top-down motivations, they contain phenomenologically interesting states with leptoquark quantum numbers. Their SUSY partners, leptoquarkinos, will appear similar to all R-odd particles in decay cascades, but mass edges in kinematic distributions—originating from the same semiexclusive final states—will however have major differences to the corresponding edges of ordinary squarks. This distortion of standard observables bears the opportunity to detect them at the LHC, but may also pose significant confusion of underlying model assumptions, which should be handled with care and, if interpreted falsely, might even prevent a possible discovery.

  20. Mosquitoes on the Wing ``Tune In'' to Acoustic Distortion

    NASA Astrophysics Data System (ADS)

    Warren, Ben; Russell, Ian

    2011-11-01

    Our current understanding of the mating game for many mosquito species is that males aggregate in noisy mating swarms and listen with their Johnston's organs (JOs) for the deeper flight tones of approaching females, to which they are attracted. As has been demonstrated, at least for the most intensely studied vector species, the mechanical resonance of the flagellum and the frequency range of the female's JO is far below that of the male's flight tones. Therefore, it has been assumed that females do not use hearing to detect the presence of males. Here we reveal that this may not be the case, and that the JOs of female Culex quinquefasciatus are exquisitely tuned to low frequency distortion products in the vibrations of the antenna due to a nonlinear interaction between her own flight tones and those of a nearby male. She can hear male flight tones by virtue of, and not despite, hearing her own flight tones.

  1. Active scale changer for anamorphic, distortion free, telecentric zoom system

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Hugot, Emmanuel; Bernard, Anaïs.; Madec, Fabrice; Lemared, Sabri

    2014-07-01

    We present the conception of an anamorphic and telecentric scale changer with no distortion, able to provide magnifications in the range of 2 to 30 without any interchangeable optics, dedicated to ground or space applications. Several optical designs are investigated and the final configuration is based on off-axis five mirrors system with no moving elements. Four active mirrors are adapted to four different zoom configurations. A specific mechanical profile with variable thickness distribution is simulated and optimized on each mirror to allow using a minimal number of actuators. An opto-mechanical design will be presented, showing the implementation of actuators on the system. This work is done in the frame of the ANR project OASIX and will produce a lab prototype in 2015.

  2. Sub-Nyquist Sampling and Moire-Like Waveform Distortions

    NASA Technical Reports Server (NTRS)

    Williams, Glenn L.

    2000-01-01

    Investigations of aliasing effects in digital waveform sampling have revealed the existence of a mathematical field and a pseudo-alias domain lying to the left of a "Nyquist line" in a plane defining the boundary between two domains of sampling. To the right of the line lies the classic alias domain. For signals band-limited below the Nyquist limit, displayed output may show a false modulation envelope. The effect occurs whenever the sample rate and the signal frequency are related by ratios of mutually prime integers. Belying the principal of a 10:1 sampling ratio being "good enough", this distortion easily occurs in graphed one-dimensional waveforms and two-dimensional images and occurs daily on television.

  3. Phonon triggered rhombohedral lattice distortion in vanadium at high pressure

    NASA Astrophysics Data System (ADS)

    Antonangeli, Daniele; Farber, Daniel L.; Bosak, Alexei; Aracne, Chantel M.; Ruddle, David G.; Krisch, Michael

    2016-08-01

    In spite of the simple body-centered-cubic crystal structure, the elements of group V, vanadium, niobium and tantalum, show strong interactions between the electronic properties and lattice dynamics. Further, these interactions can be tuned by external parameters, such as pressure and temperature. We used inelastic x-ray scattering to probe the phonon dispersion of single-crystalline vanadium as a function of pressure to 45 GPa. Our measurements show an anomalous high-pressure behavior of the transverse acoustic mode along the (100) direction and a softening of the elastic modulus C44 that triggers a rhombohedral lattice distortion occurring between 34 and 39 GPa. Our results provide the missing experimental confirmation of the theoretically predicted shear instability arising from the progressive intra-band nesting of the Fermi surface with increasing pressure, a scenario common to all transition metals of group V.

  4. Orbit and Optics Distortion in a Nonscaling Muon FFAG

    SciTech Connect

    Machida, Shinji

    2008-02-21

    Finite chromaticity in a nonscaling FFAG makes transverse tunes move during acceleration. Particles have to cross many integer and half-integer resonances although all those tunes are imperfection ones. Plausible argument is that the acceleration is so fast that effects of those resonance crossings are marginal. We did a tracking study in a lattice with alignment and gradient errors to see how the orbit and optics distortion is excited. We found that in a time scale of the muon acceleration, namely total tune changes about one unit per turn, the resonance is not a proper way to describe the beam dynamics. Instead, a random walk model, in which we assume that alignment and gradient errors kick a particle randomly in phase space, well explains the tracking results.

  5. Phonon triggered rhombohedral lattice distortion in vanadium at high pressure

    PubMed Central

    Antonangeli, Daniele; Farber, Daniel L.; Bosak, Alexei; Aracne, Chantel M.; Ruddle, David G.; Krisch, Michael

    2016-01-01

    In spite of the simple body-centered-cubic crystal structure, the elements of group V, vanadium, niobium and tantalum, show strong interactions between the electronic properties and lattice dynamics. Further, these interactions can be tuned by external parameters, such as pressure and temperature. We used inelastic x-ray scattering to probe the phonon dispersion of single-crystalline vanadium as a function of pressure to 45 GPa. Our measurements show an anomalous high-pressure behavior of the transverse acoustic mode along the (100) direction and a softening of the elastic modulus C44 that triggers a rhombohedral lattice distortion occurring between 34 and 39 GPa. Our results provide the missing experimental confirmation of the theoretically predicted shear instability arising from the progressive intra-band nesting of the Fermi surface with increasing pressure, a scenario common to all transition metals of group V. PMID:27539662

  6. Polar distortions in hydrogen-bonded organic ferroelectrics

    NASA Astrophysics Data System (ADS)

    Stroppa, Alessandro; di Sante, Domenico; Horiuchi, Sachio; Tokura, Yoshinori; Vanderbilt, David; Picozzi, Silvia

    2011-07-01

    Although ferroelectric compounds containing hydrogen bonds were among the first to be discovered, organic ferroelectrics are relatively rare. The discovery of high polarization at room temperature in croconic acid [Horiuchi , Nature (London) NATUAS0028-083610.1038/nature08731463, 789 (2010)] has led to a renewed interest in organic ferroelectrics. We present an ab initio study of two ferroelectric organic molecular crystals, 1-cyclobutene-1,2-dicarboxylic acid (CBDC) and 2-phenylmalondialdehyde (PhMDA). By using a distortion-mode analysis we shed light on the microscopic mechanisms contributing to the polarization, which we find to be as large as 14.3 and 7.0 μC/cm2 for CBDC and PhMDA, respectively. These results suggest that it may be fruitful to search among known but poorly characterized organic compounds for organic ferroelectrics with enhanced polar properties suitable for device applications.

  7. Increased Insulin Sensitivity and Distorted Mitochondrial Adaptations during Muscle Unloading

    PubMed Central

    Qi, Zhengtang; Zhang, Yuan; Guo, Wei; Ji, Liu; Ding, Shuzhe

    2012-01-01

    We aimed to further investigate mitochondrial adaptations to muscle disuse and the consequent metabolic disorders. Male rats were submitted to hindlimb unloading (HU) for three weeks. Interestingly, HU increased insulin sensitivity index (ISI) and decreased blood level of triglyceride and insulin. In skeletal muscle, HU decreased expression of pyruvate dehydrogenase kinase 4 (PDK4) and its protein level in mitochondria. HU decreased mtDNA content and mitochondrial biogenesis biomarkers. Dynamin-related protein (Drp1) in mitochondria and Mfn2 mRNA level were decreased significantly by HU. Our findings provide more extensive insight into mitochondrial adaptations to muscle disuse, involving the shift of fuel utilization towards glucose, the decreased mitochondrial biogenesis and the distorted mitochondrial dynamics. PMID:23443131

  8. Distortions of glacial landform sizes by manual mapping

    NASA Astrophysics Data System (ADS)

    Hillier, John K.; Smith, Mike J.

    2016-04-01

    Mapped topographic features are important for understanding processes that sculpt the Earth's surface. Subjective manual techniques are commonly used for mapping, yet how effective they are in quantitative terms is poorly constrained. Here 12,121 outlines drawn by 25 interpreters searching for a total of 21,625 drumlins in 5 synthetic DEMs are interpreted in terms of how the manual mapping process distorts the height (H), width (W) and length (L) of the reported features. Bias in the size-frequency distributions is caused by the sub-set of the forms 'found', even assuming perfect extraction of sizes, and is governed by H driving detectability. Bias is then compounded in sizes that are extracted using the mapped outlines but, remarkably, the size-frequency distribution is not altered further when mappers' incorrect guesses (i.e. outline corresponds to no input synthetic drumlin) are then included; it seems possible that, once mappers have their 'eye in' based on the most clearly defined features, they are very effective at identifying similar morphologies. Of the metrics available to quantify the size of a population, maximum size and λ, the exponent of its tail, are the most robust to these distortions. The drumlins in the study area resemble UK drumlins, permitting extrapolation of the conclusions. These are the first results to give such granular insights into the impacts of the various stages in manually mapping glacial landforms, permitted by the development of the synthetic DEMs. Arguments will always exist about how realistic any synthetic is, but this work demonstrates another use of synthetic DEMs that may be applied more widely in geomorphology.

  9. Evaluating the evidence for transmission distortion in human pedigrees.

    PubMed

    Meyer, Wynn K; Arbeithuber, Barbara; Ober, Carole; Ebner, Thomas; Tiemann-Boege, Irene; Hudson, Richard R; Przeworski, Molly

    2012-05-01

    Children of a heterozygous parent are expected to carry either allele with equal probability. Exceptions can occur, however, due to meiotic drive, competition among gametes, or viability selection, which we collectively term "transmission distortion" (TD). Although there are several well-characterized examples of these phenomena, their existence in humans remains unknown. We therefore performed a genome-wide scan for TD by applying the transmission disequilibrium test (TDT) genome-wide to three large sets of human pedigrees of European descent: the Framingham Heart Study (FHS), a founder population of European origin (HUTT), and a subset of the Autism Genetic Resource Exchange (AGRE). Genotyping error is an important confounder in this type of analysis. In FHS and HUTT, despite extensive quality control, we did not find sufficient evidence to exclude genotyping error in the strongest signals. In AGRE, however, many signals extended across multiple SNPs, a pattern highly unlikely to arise from genotyping error. We identified several candidate regions in this data set, notably a locus in 10q26.13 displaying a genome-wide significant TDT in combined female and male transmissions and a signature of recent positive selection, as well as a paternal TD signal in 6p21.1, the same region in which a significant TD signal was previously observed in 30 European males. Neither region replicated in FHS, however, and the paternal signal was not visible in sperm competition assays or as allelic imbalance in sperm. In maternal transmissions, we detected no strong signals near centromeres or telomeres, the regions predicted to be most susceptible to female-specific meiotic drive, but we found a significant enrichment of top signals among genes involved in cell junctions. These results illustrate both the potential benefits and the challenges of using the TDT to study transmission distortion and provide candidates for investigation in future studies. PMID:22377632

  10. Intra-field overlay correction for illumination based distortion

    NASA Astrophysics Data System (ADS)

    Pike, Michael; Brunner, Timothy; Morgenfeld, Bradley; Jing, Nan; Wiltshire, Timothy

    2015-03-01

    The use of extreme freeform illumination conditions and multi patterning processes used to generate sub 40nm images can result in significant intra-field overlay errors. When levels with differing illumination conditions are aligned to each other, these intra-field distortions can result in overlay errors which are uncorrectable using normal linear feedback corrections. We use a double exposure method, previously described by Minghetti [1] et al. to isolate and measure intra-field overlay distortions caused by tool lens signatures and different illumination conditions. A full field test reticle is used to create a dual level expose pattern. The same pattern is exposed twice, but with two different illumination conditions. The first exposure is done with a standard reference illumination. The second exposure is the target illumination condition. The test reticle has overlay target pairs that are measurable when the 2nd exposure is offset in the Y direction by the designed amount. This allows for a high density, 13x13, intra-field overlay measurement to be collected and modeled to determine 2nd and 3rd order intra-field terms. Since the resulting illumination and scanner lens specific intra field corrections are independent of field size, the sub-recipes can be applied to any product exposure independent of field size, which use the same illumination conditions as the test exposures. When the method is applied to all exposure levels in a product build cycle, the overlay errors contributed by the reference illumination condition cancel out. The remaining errors are due exclusively to the impact of the illumination condition on that scanner lens. Actual results correlated well with the model with more than 80% of the predicted overlay improvement being achieved.

  11. Low color distortion adaptive dimming scheme for power efficient LCDs

    NASA Astrophysics Data System (ADS)

    Nam, Hyoungsik; Song, Eun-Ji

    2013-06-01

    This paper demonstrates the color compensation algorithm to reduce the color distortion caused by mismatches between the reference gamma value of a dimming algorithm and the display gamma values of an LCD panel in a low power adaptive dimming scheme. In 2010, we presented the YrYgYb algorithm, which used the display gamma values extracted from the luminance data of red, green, and blue sub-pixels, Yr, Yg, and Yb, with the simulation results. It was based on the ideal panel model where the color coordinates were maintained at the fixed values over the gray levels. Whereas, this work introduces an XrYgZb color compensation algorithm which obtains the display gamma values of red, green, and blue from the different tri-stimulus data of Xr, Yg, and Zb, to obtain further reduction on the color distortion. Both simulation and measurement results ensure that a XrYgZb algorithm outperforms a previous YrYgYb algorithm. In simulation which has been conducted at the practical model derived from the measured data, the XrYgZb scheme achieves lower maximum and average color difference values of 3.7743 and 0.6230 over 24 test picture images, compared to 4.864 and 0.7156 in the YrYgYb one. In measurement of a 19-inch LCD panel, the XrYgZb method also accomplishes smaller color difference values of 1.444072 and 5.588195 over 49 combinations of red, green, and blue data, compared to 1.50578 and 6.00403 of the YrYgYb at the backlight dimming ratios of 0.85 and 0.4.

  12. Human Adult Cortical Reorganization and Consequent Visual Distortion

    PubMed Central

    Dilks, Daniel D.; Serences, John T.; Rosenau, Benjamin J.; Yantis, Steven; McCloskey, Michael

    2009-01-01

    Neural and behavioral evidence for cortical reorganization in the adult somatosensory system after loss of sensory input (e.g., amputation) has been well documented. In contrast, evidence for reorganization in the adult visual system is far less clear: neural evidence is the subject of controversy, behavioral evidence is sparse, and studies combining neural and behavioral evidence have not previously been reported. Here, we report converging behavioral and neuroimaging evidence from a stroke patient (B.L.) in support of cortical reorganization in the adult human visual system. B.L.’s stroke spared the primary visual cortex (V1), but destroyed fibers that normally provide input to V1 from the upper left visual field (LVF). As a consequence, B.L. is blind in the upper LVF, and exhibits distorted perception in the lower LVF: stimuli appear vertically elongated, toward and into the blind upper LVF. For example, a square presented in the lower LVF is perceived as a rectangle extending upward. We hypothesized that the perceptual distortion was a consequence of cortical reorganization in V1. Extensive behavioral testing supported our hypothesis, and functional magnetic resonance imaging (fMRI) confirmed V1 reorganization. Together, the behavioral and fMRI data show that loss of input to V1 after a stroke leads to cortical reorganization in the adult human visual system, and provide the first evidence that reorganization of the adult visual system affects visual perception. These findings contribute to our understanding of the human adult brain’s capacity to change and has implications for topics ranging from learning to recovery from brain damage. PMID:17804619

  13. μ distortions or running: A guaranteed discovery from CMB spectrometry

    NASA Astrophysics Data System (ADS)

    Cabass, Giovanni; Melchiorri, Alessandro; Pajer, Enrico

    2016-04-01

    We discuss the implications of a PIXIE-like experiment, which would measure μ -type spectral distortions of the cosmic microwave background (CMB) at a level of σμ=(1 /n )×10-8 , with n ≥1 representing an improved sensitivity (e.g. n =10 corresponds to PRISM). Using Planck data and considering the six-parameter Λ CDM model, we compute the posterior for μ8≡μ ×108 and find μ8=1.5 7-0.13+0.11 (68% C.L.). This becomes μ8=1.2 8-0.52+0.30 (68% C.L.) when the running αs of the spectral index is included. We point out that a sensitivity of about 3 ×PIXIE implies a guaranteed discovery: μ distortion is detected or αs≥0 is excluded (both at 95% C.L. or higher). This threshold sensitivity sets a clear benchmark for CMB spectrometry. For a combined analysis of PIXIE and current Planck data, we discuss the improvement on measurements of the tilt ns and the running αs and the dependence on the choice of the pivot. A fiducial running of αs=-0.01 (close to the Planck best fit) leads to a detection of negative running at 2 σ for 5 ×PIXIE . A fiducial running of αs=-0.02 , still compatible with Planck, requires 3 ×PIXIE to rule out αs=0 (at 95% C.L.). We propose a convenient and compact visualization of the improving constraints on the tilt, running and tensor-to-scalar ratio.

  14. The phenomenology of body image distortions induced by regional anaesthesia.

    PubMed

    Paqueron, X; Leguen, M; Rosenthal, D; Coriat, P; Willer, J C; Danziger, N

    2003-03-01

    Patients with peripheral nerve or spinal cord lesions frequently report perceptual distortions related to position, shape, texture or temperature of the affected areas. This study aimed to describe the phenomenology of such body image alterations during the course of upper limb, lower limb or spinal anaesthetic blocks in patients (n = 36) undergoing orthopaedic surgery. Multimodal sensory testing and assessment of motor function were performed at regular intervals, and the relationship between the reported body image distortions and the progression of sensory and motor impairment was analysed. We found that perceptual changes concerning the shape and size of the deafferented limb occurred in the great majority of patients. In all of them, illusions of swelling, elongation or shortening of the limb coincided with the impairment of warm, cold and/or pinprick sensations, suggesting that thin myelinated Adelta- and/or unmyelinated C-fibres may provide a source of tonic modulation to the limb's cortical representation. Such perceptual alterations of shape and size of body parts differed clearly from postural illusions in terms of frequency, time course and influence of vision. In addition to perceptual changes in the deafferented area, almost half of the patients felt their unanaesthetized lips and/or mouth swelling during the course of upper limb block, suggesting the unmasking of dynamic interactions between somatotopically adjacent cortical representations. Conflicting sensations could co-exist in the patient's body image, such as the illusion of swelling of a limb, which, at the same time, was felt to be missing. The sense of ownership of the deafferented limb was impaired in some cases. These observations show that the perception of body shape and the awareness of its postural variations are built from different plastic models. They also underline the contribution of peripheral afferent activity to the maintenance of a unified body image.

  15. Abortion and distortion of justice in the law.

    PubMed

    Dickens, B M

    1989-01-01

    Examples are cited of how the current policy in the U.S. favoring the pro-life philosophy is distorting government and court judgements. Appointment of Supreme Court justices and executive officials higher than assistant cabinet secretaries is subject to political ideology. Pro-life activists oppose wrongful birth tort actions, with the result that handicapped children are denied damages. In contrast they support legal action on behalf of stillborn fetuses. Similarly since "Webster" the pro-life movement disallows wrongful birth suits, so financial expenses cannot be recovered to help pay for a handicapped child. This may paradoxically force couples into abortion if they cannot risk supporting a severely handicapped child. Again, the trend is the same for wrongful life claims where handicapped children as a result of professional negligence seek compensation to provide for their care. Stillborn fetuses in this case can recover damages, resulting in windfall gains to their estate. The possibility of finding on behalf of a stillborn fetus may prompt doctors to induce abortion rather than have to pay damages. Another distortion of the notion of the transcending blessing of life valued more in the abstract than an individual's suffering or insentience is the judgement that comatose persons must continue to receive forced life-support against their family's claim of right to decline care. There have been a few cases where pregnant women have been charged as criminals, forcibly hospitalized and operated on to legally protect the fetus. This trend may cause pregnant women to avoid prenatal care rather than be forced to live a state-prescribed life style. Other examples of misdirected compassion of the pro-life movement are loss of practicing obstetricians, of RU 486 and other contraceptive methods, of fetal tissue research, and potential loss of in vitro fertilization to couples who wish to have 1 or 2 babies only.

  16. Variance After-Effects Distort Risk Perception in Humans.

    PubMed

    Payzan-LeNestour, Elise; Balleine, Bernard W; Berrada, Tony; Pearson, Joel

    2016-06-01

    In many contexts, decision-making requires an accurate representation of outcome variance-otherwise known as "risk" in economics. Conventional economic theory assumes this representation to be perfect, thereby focusing on risk preferences rather than risk perception per se [1-3] (but see [4]). However, humans often misrepresent their physical environment. Perhaps the most striking of such misrepresentations are the many well-known sensory after-effects, which most commonly involve visual properties, such as color, contrast, size, and motion. For example, viewing downward motion of a waterfall induces the anomalous biased experience of upward motion during subsequent viewing of static rocks to the side [5]. Given that after-effects are pervasive, occurring across a wide range of time horizons [6] and stimulus dimensions (including properties such as face perception [7, 8], gender [9], and numerosity [10]), and that some evidence exists that neurons show adaptation to variance in the sole visual feature of motion [11], we were interested in assessing whether after-effects distort variance perception in humans. We found that perceived variance is decreased after prolonged exposure to high variance and increased after exposure to low variance within a number of different visual representations of variance. We demonstrate these after-effects occur across very different visual representations of variance, suggesting that these effects are not sensory, but operate at a high (cognitive) level of information processing. These results suggest, therefore, that variance constitutes an independent cognitive property and that prolonged exposure to extreme variance distorts risk perception-a fundamental challenge for economic theory and practice. PMID:27161500

  17. Analytical models for use in fan inflow control structure design. Inflow distortion and acoustic transmission models

    NASA Technical Reports Server (NTRS)

    Gedge, M. R.

    1979-01-01

    Analytical models were developed to study the effect of flow contraction and screening on inflow distortions to identify qualitative design criteria. Results of the study are that: (1) static testing distortions are due to atmospheric turbulence, nacelle boundary layer, exhaust flow reingestion, flow over stand, ground plane, and engine casing; (2) flow contraction suppresses, initially, turbulent axial velocity distortions and magnifies turbulent transverse velocity distortions; (3) perforated plate and gauze screens suppress axial components of velocity distortions to a degree determined by the screen pressure loss coefficient; (4) honeycomb screen suppress transverse components of velocity distortions to a degree determined by the length to diameter ratio of the honeycomb; (5) acoustic transmission loss of perforated plate is controlled by the reactance of its acoustic impedance; (6) acoustic transmission loss of honeycomb screens is negligible; and (7) a model for the direction change due to a corner between honeycomb panels compares favorably with measured data.

  18. Weld Bead Distortion of Thin-Plate Using Weak Digital Image Correlation Method

    NASA Astrophysics Data System (ADS)

    Guo, Nan; Yin, Xianqing; Liang, Jin; Ma, Ninshu

    2016-09-01

    Currently, the primary method used to investigate weld bead distortions is based on finite element prediction. However, in this paper, we proposed a three-dimensional optical method based on weak digital image correlation technology to track the dynamic distortion of the weld bead throughout the welding and cooling process. An experimental investigation demonstrated that the weld bead zone was distorted into a dish shape during the welding process and changed into a saddle shape after cooling down. In the weld bead, the out-of-plate distortion was significantly larger than the in-plate distortion, and the longitudinal plastic strain distribution was small and uniform, whereas the transverse strain was larger. This optical experimental method could be useful in the validation of numerical models in the welding process and important to research on welding distortions.

  19. Increasing honest responding on cognitive distortions in child molesters: the bogus pipeline procedure.

    PubMed

    Gannon, Theresa A

    2006-03-01

    Professionals conclude that child molesters (CMs) hold offense-supportive beliefs (or cognitive distortions) from CMs'questionnaire responses. Because questionnaires are easily faked, we asked 32 CMs to complete a cognitive distortion scale under standard conditions (Time 1). A week later (Time 2), the same CMs completed the scale again. This time, approximately one half of CMs were attached to a pseudo lie detector (a bogus pipeline), and the rest completed the scale again under standard conditions (controls). At Time 1, CMs showed low cognitive distortion scores, seeming to indicate that they were faking good. At Time 2, bogus pipeline CMs seemed to believe that the apparatus could detect lies. However, this did not encourage more distorted belief disclosure compared with (a) their own previous scores and (b) controls. Furthermore, the bogus pipeline appeared to reduce cognitive distortion endorsements. The results stand in marked contrast to the common view that most CMs hold distorted beliefs.

  20. A study of the effect of group delay distortion on an SMSK satellite communications channel

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.

    1987-01-01

    The effects of group delay distortion on an SMSK satellite communications channel have been investigated. Software and hardware simulations have been used to determine the effects of channel group delay variations with frequency on the bit error rate for a 220 Mbps SMSK channel. These simulations indicate that group delay distortions can significantly degrade the bit error rate performance. The severity of the degradation is dependent on the amount, type, and spectral location of the group delay distortion.

  1. Investigation of support vector machine for the detection of architectural distortion in mammographic images

    NASA Astrophysics Data System (ADS)

    Guo, Q.; Shao, J.; Ruiz, V.

    2005-01-01

    This paper investigates detection of architectural distortion in mammographic images using support vector machine. Hausdorff dimension is used to characterise the texture feature of mammographic images. Support vector machine, a learning machine based on statistical learning theory, is trained through supervised learning to detect architectural distortion. Compared to the Radial Basis Function neural networks, SVM produced more accurate classification results in distinguishing architectural distortion abnormality from normal breast parenchyma.

  2. Trapped fermionic clouds distorted from the trap shape due to many-body effects.

    PubMed

    Haque, Masudul; Stoof, H T C

    2007-06-29

    We present a general approach for describing trapped Fermi gases, when the cloud shape is distorted with respect to the trap shape. Our approach provides a consistent way to explore physics beyond the local density approximation, if this is necessary due to the distortion. We illustrate this by analyzing in detail experimentally observed distortions in a trapped imbalanced Fermi mixture. In particular, we demonstrate in that case dramatic deviations from ellipsoidal cloud shapes arising from the competition between surface and bulk energies.

  3. Crossover from Peierls distortion to one-dimensional superconductivity in arrays of (5,0) carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhang, Ting; Sun, Ming Yuan; Wang, Zhe; Shi, Wu; Sheng, Ping

    2011-12-01

    By performing second-order renormalization group analysis on thin arrays of 4-Angstrom (5,0) carbon nanotubes (CNTs) embedded in aluminophosphate-five (AFI) zeolite crystals, we identify singlet superconductivity instability to be dominant at low temperatures, attributable to the screening of the electron-electron Coulomb interaction in the array configuration. Our analysis also shows that there is a crossover as the system scales to lower energy/temperatures, whereby one-dimensional (1D) superconductivity is the ground state, but the response function of the Peierls distortion/charge density wave (CDW) order dominates at the higher energy regime. This crossover behavior indicates that for a thin array of (5,0) CNTs the CDW order may represent an excited state of the array, so that the CDW characteristics can appear at finite temperatures, in conjunction with 1D superconductivity. Experimental results are presented to support this interpretation.

  4. Limits of the plane wave approximation in the measurement of molecular properties.

    PubMed

    Walters, Zachary B; Tonzani, Stefano; Greene, Chris H

    2008-10-01

    Rescattering electrons offer great potential as probes of molecular properties on ultrafast timescales. The most famous example is molecular tomography, in which high harmonic spectra of oriented molecules are mapped to "tomographic images" of the relevant molecular orbitals. The accuracy of such reconstructions can be greatly affected by the distortion of scattering wave functions from their asymptotic forms due to interactions with the parent ion. We investigate the validity of the commonly used plane wave approximation in molecular tomography, showing how such distortions affect the resulting orbital reconstructions.

  5. Characterization and Correction of Geometric Distortions in 814 Diffusion Weighted Images

    PubMed Central

    Treiber, Jeffrey Mark; White, Nathan S.; Steed, Tyler Christian; Bartsch, Hauke; Holland, Dominic; Farid, Nikdokht; McDonald, Carrie R.; Carter, Bob S.

    2016-01-01

    Introduction Diffusion Weighted Imaging (DWI), which is based on Echo Planar Imaging (EPI) protocols, is becoming increasingly important for neurosurgical applications. However, its use in this context is limited in part by significant spatial distortion inherent to EPI. Method We evaluated an efficient algorithm for EPI distortion correction (EPIC) across 814 DWI scans from 250 brain tumor patients and quantified the magnitude of geometric distortion for whole brain and multiple brain regions. Results Evaluation of the algorithm’s performance revealed significantly higher mutual information between T1-weighted pre-contrast images and corrected b = 0 images than the uncorrected b = 0 images (p < 0.001). The distortion magnitude across all voxels revealed a median EPI distortion effect of 2.1 mm, ranging from 1.2 mm to 5.9 mm, the 5th and 95th percentile, respectively. Regions adjacent to bone-air interfaces, such as the orbitofrontal cortex, temporal poles, and brain stem, were the regions most severely affected by DWI distortion. Conclusion Using EPIC to estimate the degree of distortion in 814 DWI brain tumor images enabled the creation of a topographic atlas of DWI distortion across the brain. The degree of displacement of tumors boundaries in uncorrected images is severe but can be corrected for using EPIC. Our results support the use of distortion correction to ensure accurate and careful application of DWI to neurosurgical practice. PMID:27027775

  6. Measurement of microtomy-induced section distortion and its correction for 3-dimensional histological reconstructions.

    PubMed

    Jones, A S; Milthorpe, B K; Howlett, C R

    1994-02-01

    The presence of microtomy induced distortion in paraffin sections is a significant hindrance to the accurate alignment of sections for three-dimensional reconstructive techniques. Measurements of section distortion in various rat tissues demonstrated distortions to be present in all sections, with over 85% of such distortions being manifest as expansions when compared to the original distances between a series of eight drilled fiducial marks. Mean percentage dimensional changes in the direction of the cutting stroke and at right angles to this direction were -0.5 +/- 1.5% and 3.7 +/- 1.2% for liver, 7.6 +/- 2.4% and 9.1 +/- 1.2% for kidney, 6.6 +/- 2.3% and 10.5 +/- 1.4% for lung, and 20.3 +/- 6.6% and 8.9 +/- 5.9% for skeletal muscle. Individual sections invariably displayed measurable distortions, with only skeletal muscle showing any consistent pattern, in the form of "barrel" distortion at right angles to the cutting stroke. In addition a method of distortion correction and simultaneous image alignment is presented as a means of section alignment with full distortion correction capability. This method uses a quadratic polynomial transform in a non-linear "unwarping" algorithm, to correct for the rotational and translational misalignment as well as for microtomy and camera aspect ratio distortions. Application of this method to a sequence of 46 serial sections demonstrated an alignment accuracy to within 2.6 +/- 0.8 pixels.

  7. Subjective audio quality evaluation of embedded-optimization-based distortion precompensation algorithms.

    PubMed

    Defraene, Bruno; van Waterschoot, Toon; Diehl, Moritz; Moonen, Marc

    2016-07-01

    Subjective audio quality evaluation experiments have been conducted to assess the performance of embedded-optimization-based precompensation algorithms for mitigating perceptible linear and nonlinear distortion in audio signals. It is concluded with statistical significance that the perceived audio quality is improved by applying an embedded-optimization-based precompensation algorithm, both in case (i) nonlinear distortion and (ii) a combination of linear and nonlinear distortion is present. Moreover, a significant positive correlation is reported between the collected subjective and objective PEAQ audio quality scores, supporting the validity of using PEAQ to predict the impact of linear and nonlinear distortion on the perceived audio quality. PMID:27475197

  8. Effects of amplitude distortions and IF equalization on satellite communication system bit-error rate performance

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Fujikawa, Gene; Svoboda, James S.; Lizanich, Paul J.

    1990-01-01

    Satellite communications links are subject to distortions which result in an amplitude versus frequency response which deviates from the ideal flat response. Such distortions result from propagation effects such as multipath fading and scintillation and from transponder and ground terminal hardware imperfections. Bit-error rate (BER) degradation resulting from several types of amplitude response distortions were measured. Additional tests measured the amount of BER improvement obtained by flattening the amplitude response of a distorted laboratory simulated satellite channel. The results of these experiments are presented.

  9. Effects of amplitude distortions and IF equalization on satellite communication system bit-error rate performance

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Fujikawa, Gene; Svoboda, James S.; Lizanich, Paul J.

    1990-01-01

    Satellite communications links are subject to distortions which result in an amplitude versus frequency response which deviates from the ideal flat response. Such distortions result from propagation effects such as multipath fading and scintillation and from transponder and ground terminal hardware imperfections. Laboratory experiments performed at NASA Lewis measured the bit-error-rate (BER) degradation resulting from several types of amplitude response distortions. Additional tests measured the amount of BER improvement obtained by flattening the amplitude response of a distorted laboratory-simulated satellite channel. This paper presents the results of these experiments.

  10. Investigations on an axial flow fan stage subjected to circumferential inlet flow distortion and swirl

    NASA Astrophysics Data System (ADS)

    Govardhan, M.; Viswanath, K.

    1997-12-01

    The combined effects of swirl and circumferential inlet flow distortion on the flow field of an axial flow fan stage are reported in this paper. The study involves measurements at the inlet of the rotor and exit of the rotor and stator at design and off design flow conditions. The study indicated that at the design flow condition, swirl had caused deterioration of the performance in addition to that caused by distortion. Pressure rise imparted in the distortion zone is higher than in the free zone. The attenuation of distortion is high in the presence of swirl.

  11. Study of the Usefulness of the 3D-distortion Correction in MRI.

    PubMed

    Yasuda, Shino; Yamakoshi, Kazunori

    2016-09-01

    Static magnetic field non-uniformity and gradient magnetic field non-linearity can be considered as the causes of geometric distortion in MRI images. The impact of a distortion in imaging such as whole body imaging or whole spine imaging can be serious. A standard 2D-distortion correction method does not correct the distortion in the slice encoding direction. This study examined the effect of 3D-distortion correction with a correction effect in both the imaging plane and the slice-encoding plane using three MRI devices with differing static magnetic field intensities and boa diameters. Imaging of a nickel sulfate bottle phantom attached to the MRI device was conducted using a CT scan to measure the distortion rate based on the CT image. The result of the distortion rate at -39.1% in the Z-axis direction was reduced to -1.3%, and the distortion rate at about -9.8% in the magnetic X-axis was reduced to -1.7%. In addition, the reduction effect was greater on the 70 cm boa device compared to the 60 cm boa device, and it was also greater at 1.5 T compared to 3 T. 3D-distortion correction is believed to be useful for wide scope imaging using large FOV. PMID:27647597

  12. Comparative Analysis of Regions with Distorted Segregation in Three Diploid Populations of Potato

    PubMed Central

    Manrique-Carpintero, Norma C.; Coombs, Joseph J.; Veilleux, Richard E.; Buell, C. Robin; Douches, David S.

    2016-01-01

    Genes associated with gametic and zygotic selection could underlie segregation distortion, observed as alterations of expected Mendelian genotypic frequencies in mapping populations. We studied highly dense genetic maps based on single nucleotide polymorphisms to elucidate the genetic nature of distorted segregation in potato. Three intra- and interspecific diploid segregating populations were used. DRH and D84 are crosses between the sequenced doubled monoploid DM 1-3 516 R44 Solanum tuberosum Group Phureja and either RH89-039-16 S. tuberosum or 84SD22, a S. tuberosum × S. chacoense hybrid. MSX902 is an interspecific cross between 84SD22 and Ber83 S. berthaultii × 2 × species mosaic. At the 0.05 significance level, 21%, 57%, and 51% of the total markers mapped in DRH, D84, and MSX902 exhibited distorted segregation, respectively. Segregation distortion regions for DRH were located on chromosomes 9 and 12; for D84 on chromosomes 2, 3, 4, 6, 7, and 8; and on chromosomes 1, 2, 7, 9, and 12 for MSX902. In general, each population had unique segregation distortion regions and directions of distortion. Interspecific crosses showed greater levels of distorted segregation and lower recombination rates as determined from the male parents. The different genomic regions where the segregation distortion regions occurred in the three populations likely reflect unique genetic combinations producing distorted segregation. PMID:27342736

  13. Subjective audio quality evaluation of embedded-optimization-based distortion precompensation algorithms.

    PubMed

    Defraene, Bruno; van Waterschoot, Toon; Diehl, Moritz; Moonen, Marc

    2016-07-01

    Subjective audio quality evaluation experiments have been conducted to assess the performance of embedded-optimization-based precompensation algorithms for mitigating perceptible linear and nonlinear distortion in audio signals. It is concluded with statistical significance that the perceived audio quality is improved by applying an embedded-optimization-based precompensation algorithm, both in case (i) nonlinear distortion and (ii) a combination of linear and nonlinear distortion is present. Moreover, a significant positive correlation is reported between the collected subjective and objective PEAQ audio quality scores, supporting the validity of using PEAQ to predict the impact of linear and nonlinear distortion on the perceived audio quality.

  14. Tomosynthesis-detected Architectural Distortion: Management Algorithm with Radiologic-Pathologic Correlation.

    PubMed

    Durand, Melissa A; Wang, Steven; Hooley, Regina J; Raghu, Madhavi; Philpotts, Liane E

    2016-01-01

    As use of digital breast tomosynthesis becomes increasingly widespread, new management challenges are inevitable because tomosynthesis may reveal suspicious lesions not visible at conventional two-dimensional (2D) full-field digital mammography. Architectural distortion is a mammographic finding associated with a high positive predictive value for malignancy. It is detected more frequently at tomosynthesis than at 2D digital mammography and may even be occult at conventional 2D imaging. Few studies have focused on tomosynthesis-detected architectural distortions to date, and optimal management of these distortions has yet to be well defined. Since implementing tomosynthesis at our institution in 2011, we have learned some practical ways to assess architectural distortion. Because distortions may be subtle, tomosynthesis localization tools plus improved visualization of adjacent landmarks are crucial elements in guiding mammographic identification of elusive distortions. These same tools can guide more focused ultrasonography (US) of the breast, which facilitates detection and permits US-guided tissue sampling. Some distortions may be sonographically occult, in which case magnetic resonance imaging may be a reasonable option, both to increase diagnostic confidence and to provide a means for image-guided biopsy. As an alternative, tomosynthesis-guided biopsy, conventional stereotactic biopsy (when possible), or tomosynthesis-guided needle localization may be used to achieve tissue diagnosis. Practical uses for tomosynthesis in evaluation of architectural distortion are highlighted, potential complications are identified, and a working algorithm for management of tomosynthesis-detected architectural distortion is proposed. PMID:26963448

  15. Response of a small-turboshaft-engine compression system to inlet temperature distortion

    NASA Technical Reports Server (NTRS)

    Biesiadny, T. J.; Klann, G. A.; Little, J. K.

    1984-01-01

    An experimental investigation was conducted into the response of a small-turboshaft-engine compression system to steady-state and transient inlet temperature distortions. Transient temperature ramps range from less than 100 K/sec to above 610 K/sec and generated instantaneous temperatures to 420 K above ambient. Steady-state temperature distortion levels were limited by the engine hardware temperature list. Simple analysis of the steady-state distortion data indicated that a particle separator at the engine inlet permitted higher levels of temperature distortion before onset of compressor surge than would be expected without the separator.

  16. Some Lower Valence Vanadium Fluorides: Their Crystal Distortions, Domain Structures, Modulated Structures, Ferrimagnetism, and Composition Dependence.

    ERIC Educational Resources Information Center

    Hong, Y. S.; And Others

    1980-01-01

    Describes some contemporary concepts unique to the structure of advanced solids, i.e., their crystal distortions, domain structures, modulated structures, ferrimagnetism, and composition dependence. (Author/CS)

  17. Study of the Usefulness of the 3D-distortion Correction in MRI.

    PubMed

    Yasuda, Shino; Yamakoshi, Kazunori

    2016-09-01

    Static magnetic field non-uniformity and gradient magnetic field non-linearity can be considered as the causes of geometric distortion in MRI images. The impact of a distortion in imaging such as whole body imaging or whole spine imaging can be serious. A standard 2D-distortion correction method does not correct the distortion in the slice encoding direction. This study examined the effect of 3D-distortion correction with a correction effect in both the imaging plane and the slice-encoding plane using three MRI devices with differing static magnetic field intensities and boa diameters. Imaging of a nickel sulfate bottle phantom attached to the MRI device was conducted using a CT scan to measure the distortion rate based on the CT image. The result of the distortion rate at -39.1% in the Z-axis direction was reduced to -1.3%, and the distortion rate at about -9.8% in the magnetic X-axis was reduced to -1.7%. In addition, the reduction effect was greater on the 70 cm boa device compared to the 60 cm boa device, and it was also greater at 1.5 T compared to 3 T. 3D-distortion correction is believed to be useful for wide scope imaging using large FOV.

  18. The role of visual similarity and memory in body model distortions.

    PubMed

    Saulton, Aurelie; Longo, Matthew R; Wong, Hong Yu; Bülthoff, Heinrich H; de la Rosa, Stephan

    2016-02-01

    Several studies have shown that the perception of one's own hand size is distorted in proprioceptive localization tasks. It has been suggested that those distortions mirror somatosensory anisotropies. Recent research suggests that non-corporeal items also show some spatial distortions. In order to investigate the psychological processes underlying the localization task, we investigated the influences of visual similarity and memory on distortions observed on corporeal and non-corporeal items. In experiment 1, participants indicated the location of landmarks on: their own hand, a rubber hand (rated as most similar to the real hand), and a rake (rated as least similar to the real hand). Results show no significant differences between rake and rubber hand distortions but both items were significantly less distorted than the hand. Experiments 2 and 3 explored the role of memory in spatial distance judgments of the hand, the rake and the rubber hand. Spatial representations of items measured in experiments 2 and 3 were also distorted but showed the tendency to be smaller than in localization tasks. While memory and visual similarity seem to contribute to explain qualitative similarities in distortions between the hand and non-corporeal items, those factors cannot explain the larger magnitude observed in hand distortions.

  19. Gravitational-wave detection using redshifted 21-cm observations

    SciTech Connect

    Bharadwaj, Somnath; Guha Sarkar, Tapomoy

    2009-06-15

    A gravitational-wave traversing the line of sight to a distant source produces a frequency shift which contributes to redshift space distortion. As a consequence, gravitational waves are imprinted as density fluctuations in redshift space. The gravitational-wave contribution to the redshift space power spectrum has a different {mu} dependence as compared to the dominant contribution from peculiar velocities. This, in principle, allows the two signals to be separated. The prospect of a detection is most favorable at the highest observable redshift z. Observations of redshifted 21-cm radiation from neutral hydrogen hold the possibility of probing very high redshifts. We consider the possibility of detecting primordial gravitational waves using the redshift space neutral hydrogen power spectrum. However, we find that the gravitational-wave signal, though present, will not be detectable on superhorizon scales because of cosmic variance and on subhorizon scales where the signal is highly suppressed.

  20. On neutron surface waves

    SciTech Connect

    Ignatovich, V. K.

    2009-01-15

    It is shown that neutron surface waves do not exist. The difference between the neutron wave mechanics and the wave physics of electromagnetic and acoustic processes, which allows the existence of surface waves, is analyzed.