Sample records for random scattering effects

  1. Color effects from scattering on random surface structures in dielectrics

    DEFF Research Database (Denmark)

    Clausen, Jeppe; Christiansen, Alexander B; Garnæs, Jørgen


    We show that cheap large area color filters, based on surface scattering, can be fabricated in dielectric materials by replication of random structures in silicon. The specular transmittance of three different types of structures, corresponding to three different colors, have been characterized...

  2. Effective medium approximation for effective propagation constant calculation in a dense random medium. [electromagnetic wave scattering (United States)

    Zhu, P. Y.; Fung, A. K.


    The effective medium approximation (EMA) formalism developed for scalar wave calculations in solid state physics is generalized to electromagnetic wave scattering in a dense random medium. Results are applied to compute the effective propagation constant in a dense medium involving discrete spherical scatterers. When compared with a common quasicrystalline approximation (QCA), it is found that EMA accounts for backward scattering and the effect of correlation among three scatterers which are not available in QCA. It is also found that there is not much difference in the calculated normalized phase velocity between the use of these two approximations. However, there is a significant difference in the computed effective loss tangent in a nonabsorptive random medium. The computed effective loss tangent using EMA and measurements from a snow medium are compared, showing good agreement.

  3. Coherent light scattering of heterogeneous randomly rough films and effective medium in the theory of electromagnetic wave multiple scattering

    Energy Technology Data Exchange (ETDEWEB)

    Berginc, G [THALES, 2 avenue Gay-Lussac 78995 ELANCOURT (France)


    We have developed a general formalism based on Green's functions to calculate the coherent electromagnetic field scattered by a random medium with rough boundaries. The approximate expression derived makes it possible to determine the effective permittivity, which is generalised for a layer of an inhomogeneous random medium with different types of particles and bounded with randomly rough interfaces. This effective permittivity describes the coherent propagation of an electromagnetic wave in a random medium with randomly rough boundaries. We have obtained an expression, which contains the Maxwell – Garnett formula at the low-frequency limit, and the Keller formula; the latter has been proved to be in good agreement with experiments for particles whose dimensions are larger than a wavelength. (coherent light scattering)

  4. Coupled effect of stimulated Raman scattering and random lasing of dyes in multiple scattering medium (United States)

    Yashchuk, Vasil P.


    Random lasing (RL) and stimulated Raman scattering (SRS) of dye in multiple scattering media (MSM) appears simultaneously and each couple with other. This coupling has considerable influence on the SRS regularities of dye in MSM. The main feature of this impact is that RL radiation promotes the Raman lines revealing in the RL spectrum range as part of total radiation. SRS initiation occurs owing to the CARS-like mechanism provided by the two component pump: incident monochromatic radiation (laser pump) and RL radiation arising inside the MSM. It leads to important consequences: the RL spectrum must overlap with the spectral region of the possible Stokes lines of the dye; only those Stokes lines appear which are in a range of the RL spectrum; all conditions which promote RL assist SRS also. It is shown MSM promotes the best conditions for SRS and RL coupling due to optimal matching of RL localization regions and pump radiation.

  5. Scattering from randomly oriented scatterers with strong permittivity fluctuations (United States)

    Yueh, S. H.; Kong, J. A.; Shin, R. T.


    Strong permittivity fluctuation theory is used to solve the problem of scattering from a medium composed of completely randomly oriented scatterers under a low frequency limit. Gaussian statistics are not assumed for the renormalized scattering sources. Numerical results on effective permittivity are illustrated for oblate and prolate spheroidal scatterers and compared with the results for spherical scatterers. The results are consistent with discrete scatterer theory. The effective permittivity of a random medium embedded with nonspherical scatterers shows a higher imaginary part than the spherical scatterer case with equal correlation volume. Under the distorted Born approximation, the polarimetric covariance matrix for the backscattered electric field is calculated for half-space randomly oriented scatterers. The nonspherical geometry of the scatterers shows significant effects on the cross-polarized backscattering returns, and the correlation coefficient between HH and VV returns. The polarimetric backscattering coefficients can provide useful information in distinguishing the geometry of scatterers.

  6. Electromagnetic scattering from random media

    CERN Document Server

    Field, Timothy R


    - ;The book develops the dynamical theory of scattering from random media from first principles. Its key findings are to characterize the time evolution of the scattered field in terms of stochastic differential equations, and to illustrate this framework

  7. A random matrix approach to detect defects in a strongly scattering polycrystal: How the memory effect can help overcome multiple scattering (United States)

    Shahjahan, S.; Aubry, A.; Rupin, F.; Chassignole, B.; Derode, A.


    We report on ultrasonic imaging in a random heterogeneous medium. The goal is to detect flaws embedded deeply into a polycrystalline material. A 64-element array of piezoelectric transmitters/receivers at a central frequency of 5 MHz is used to capture the Green's matrix in a backscattering configuration. Because of multiple scattering, conventional imaging completely fails to detect the deepest flaws. We utilize a random matrix approach, taking advantage of the deterministic coherence of the backscattered wave-field which is characteristic of single scattering and related to the memory effect. This allows us to separate single and multiple scattering contributions. As a consequence, we show that flaws are detected beyond the conventional limit, as if multiple scattering had been overcome.

  8. Wave propagation and scattering in random media

    CERN Document Server

    Ishimaru, Akira


    Wave Propagation and Scattering in Random Media, Volume 2, presents the fundamental formulations of wave propagation and scattering in random media in a unified and systematic manner. The topics covered in this book may be grouped into three categories: waves in random scatterers, waves in random continua, and rough surface scattering. Random scatterers are random distributions of many particles. Examples are rain, fog, smog, hail, ocean particles, red blood cells, polymers, and other particles in a state of Brownian motion. Random continua are the media whose characteristics vary randomly an

  9. Quantum optics in multiple scattering random media

    DEFF Research Database (Denmark)

    Lodahl, Peter

    Quantum Optics in Multiple Scattering Random Media Peter Lodahl Research Center COM, Technical University of Denmark, Dk-2800 Lyngby, Denmark. Coherent transport of light in a disordered random medium has attracted enormous attention both from a fundamental and application point of view. Coherent...... quantum optics in multiple scattering media and novel fundamental phenomena have been predicted when examining quantum fluctuations instead of merely the intensity of the light [1]. Here I will present the first experimental study of the propagation of quantum noise through an elastic, multiple scattering...

  10. Scattering of electromagnetic waves from a randomly perturbed quasiperiodic surface (United States)

    Shin, R. T.; Kong, J. A.


    Electromagnetic-wave scattering by a quasi-periodic surface with random perturbations (as in the remote sensing of plowed fields) is investigated analytically, applying the Kirchhoff approximation and modeling the plowed fields by means of Gaussian random variation, sinusoidal variation, and Gaussian random variation about the spatial frequency. Coherent and incoherent bistatic scattering coefficients are derived in closed form by evaluating the physical-optics integral and shown to be proportional, in the geometric-optics limit, to the occurrence probability of slopes which reflect the incident wave specularly in the direction of the scattered wave. Backscattering cross sections are plotted as functions of incidence angle for a number of cases, demonstrating the strong effect of row direction.

  11. Electromagnetic scattering by spheroidal volumes of discrete random medium (United States)

    Mishchenko, Michael I.; Dlugach, Janna M.


    We use the superposition T-matrix method to compare the far-field scattering matrices generated by spheroidal and spherical volumes of discrete random medium having the same volume and populated by identical spherical particles. Our results fully confirm the robustness of the previously identified coherent and diffuse scattering regimes and associated optical phenomena exhibited by spherical particulate volumes and support their explanation in terms of the interference phenomenon coupled with the order-of-scattering expansion of the far-field Foldy equations. We also show that increasing nonsphericity of particulate volumes causes discernible (albeit less pronounced) optical effects in forward and backscattering directions and explain them in terms of the same interference/multiple-scattering phenomenon.

  12. Spectral shifts and spectral switches produced by scattering from a random hollow scatterer with adjustable shell thickness (United States)

    Zhou, Jianyang; Zhao, Daomu


    Within the accuracy of the first-order Born approximation, the spectral shifts and spectral switches produced by the scattering of an electromagnetic light wave from a random hollow scatterer with adjustable shell thickness have been investigated. The effects of the properties of the scatterer and the incident light wave on the far-zone scattered spectrum have been discussed in detail by using numerical examples. It is shown that, as the scattering angle increases, the scattered spectrum will split into two peaks, and subsequently the two peaks will make a rapid transition as a spectral switch. The position at which the spectral switch occurs is affected by the shell thickness, the outer and inner correlation lengths of the scatterer as well as the polarization of the incident light. Besides, the polarization of the incident light also has an impact on the spectral width of the scattered field.

  13. Scattering of electromagnetic waves from random media with strong permittivity fluctuations. [with application to atmospheric turbulence effects on microwave remote sensing (United States)

    Tsang, L.; Kong, J. A.


    By taking into account the singularity of the dyadic Green's function in the renormalization method, a theory is derived for vector electromagnetic wave propagation in a random medium with large permittivity fluctuations and with anisotropic correlation function. The strong fluctuation theory is then applied to a discrete scatterer problem in which the permittivity can assume only two values. The results are found to be consistent with those derived from discrete scatterer theory for all values of dielectric constants of the scatterers.

  14. Effect of photonic stop-band on the modes of a weakly scattering DCM-PVA waveguide random laser (United States)

    Sarkar, Anirban; Ojha, N. N. Subhashree; Bhaktha, B. N. Shivakiran


    We present an experimental study on the effect of the photonic stop-band (PSB) on the random laser (RL) emission characteristics of a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) doped polyvinyl alcohol (PVA) film (DCM-PVA). The film, having its refractive index greater than the substrate and density variations at the microscopic scale, acts as a disordered active planar waveguide. The propagation losses for the transverse magnetic (TM) and transverse electric (TE) modes of the waveguide are observed to be 0.50 and 0.74 dB/cm, respectively, at λ = 632.8 nm. The waveguiding DCM-PVA film is then sandwiched between two silica 3-D photonic crystals (opals). The overlap of the DCM-PVA photoluminescence with the PSB of the opals is controlled by the choice of the particle size used for opal fabrication. The random lasing threshold studies have been carried out for both TM and TE polarizations for opals with different particle sizes. A reduction in the threshold of RL emission, with respect to the DCM-PVA waveguide, by about 20 times (to 0.67 mJ/cm2) is observed when the photoluminescence of the DCM-PVA film overlaps with the PSB of the opal structure for TM polarization, showing that the embedding of an RL in an engineered PSB material is an effective way to reduce the thresholds of RLs.

  15. Ultrathin wide bandwidth metamaterial absorber using randomly distributed scatterers (United States)

    Ahmadi, Farzad; Ida, Nathan


    In this paper, a broadband, ultrathin metamaterial absorber (MA) using randomly distributed scatterers is presented. Each scattering element consists of two parallel strips. These elements can either be isolated or they may overlap with nearby elements. Three different randomly positioned structures are investigated for normal incident angle as well as oblique incident angles showing that these MAs can provide broadband absorption for all cases. The results presented here coincide with some previous works. Each structure obviously has different absorption spectrum and FWHM since the coupling between the randomly positioned scatterers is different in each case. The coupling between neighboring isolated and clustered scatterers form many resonating modes resulting in broadband absorption. The distribution of the electromagnetic fields are analyzed to obtain the physical behavior of the absorber. This shows that promising results can still be obtained for MAs when there is a significant tolerance distance between scatterers due to fabrication errors in micro and nanoscale metadevices.

  16. Quantum optics in multiple scattering random media

    NARCIS (Netherlands)

    Lodahl, P.; Lagendijk, Aart


    The paper presents the first experimental study of the propagation of quantum noise through an elastic, multiple scattering medium. Two different types of quantum noise measurements have been carried out: total transmission and short-range frequency correlations. When comparing shot noise (quantum)

  17. Scattering of electromagnetic waves from a half-space of randomly distributed discrete scatterers and polarized backscattering ratio law (United States)

    Zhu, P. Y.


    The effective-medium approximation is applied to investigate scattering from a half-space of randomly and densely distributed discrete scatterers. Starting from vector wave equations, an approximation, called effective-medium Born approximation, a particular way, treating Green's functions, and special coordinates, of which the origin is set at the field point, are used to calculate the bistatic- and back-scatterings. An analytic solution of backscattering with closed form is obtained and it shows a depolarization effect. The theoretical results are in good agreement with the experimental measurements in the cases of snow, multi- and first-year sea-ice. The root product ratio of polarization to depolarization in backscattering is equal to 8; this result constitutes a law about polarized scattering phenomena in the nature.

  18. Strong fluctuation theory for electromagnetic wave scattering by a layer of random discrete scatterers. [in microwave remote sensing of snow fields (United States)

    Jin, Y. Q.; Kong, J. A.


    The strong fluctuation theory is applied to the study of electromagnetic wave scattering from a layer of random discrete scatterers. The singularity of the dyadic Green's function is taken into account in the calculation of the effective permittivity functions. The correlation functions for the random medium with different scatterer constituents and size distributions are derived. Applying the dyadic Green's function for a two-layer medium and using the bilocal and distorted Born approximations, the first and the second moments of the fields are then calculated. Both the backscattering and bistatic scattering coefficients are obtained, and the former is shown to match favorably with experimental data obtained from snow fields.

  19. Doppler Spectrum from Moving Scatterers in a Random Environment

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Nielsen, Jesper Ødum; Pedersen, Gert Frølund


    A random non-line-of-sight environment with stationary transmitter and receiver is considered. In such an environment movement of a scatterer will lead to perturbations of the otherwise static channel with a resulting Doppler spectrum. This is quite a general situation in outdoor environments...... with moving traffic or indoor situations with moving people. Here we study the latter situation in detail with experimental results from a large office environment. A general theory of Doppler spectra is developed. The impact of a scatterer depends on the angular distribution of scattered energy, and uniform...... as well as sharply peaked distributions are considered in the theory. The Doppler spectra are in all cases sharply peaked at zero frequency due to forward scattering, but the actually measured distribution depends on the degree and type of activity in the environment, as well as the spectrum estimation...

  20. Electrical generation of stationary light in random scattering media (United States)

    Redmond, S. M.; Armstrong, G. L.; Chan, H.-Y.; Mattson, E.; Mock, A.; Li, B.; Potts, J. R.; Cui, M.; Rand, S. C.; Oliveira, S. L.; Marchal, J.; Hinklin, T.; Laine, R. M.


    In recent years there has been great interest in controlling the speed of propagation of electromagnetic waves. In gases and crystals, coherent techniques have been applied to alter the speed of light without changing the physical or chemical structure of the medium. Also, light transmitted by highly disordered solids has exhibited signatures of Anderson localization, indicating the existence of a regime of ``stopped'' light that is mediated by random elastic scattering. However, to date, light has not been generated in a random medium as a pointlike excitation that is fixed in space from the outset. Here we report experimental evidence for the electrical generation and confinement of light within nanosized volumes of a random dielectric scattering medium in which a population inversion has been established, and discuss the properties of these novel light sources.

  1. First-principles modeling of electromagnetic scattering by discrete and discretely heterogeneous random media

    Energy Technology Data Exchange (ETDEWEB)

    Mishchenko, Michael I., E-mail: [NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 (United States); Dlugach, Janna M. [Main Astronomical Observatory of the National Academy of Sciences of Ukraine, 27 Zabolotny Str., 03680, Kyiv (Ukraine); Yurkin, Maxim A. [Voevodsky Institute of Chemical Kinetics and Combustion, SB RAS, Institutskaya str. 3, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova 2, 630090 Novosibirsk (Russian Federation); Bi, Lei [Department of Atmospheric Sciences, Texas A& M University, College Station, TX 77843 (United States); Cairns, Brian [NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 (United States); Liu, Li [NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 (United States); Columbia University, 2880 Broadway, New York, NY 10025 (United States); Panetta, R. Lee [Department of Atmospheric Sciences, Texas A& M University, College Station, TX 77843 (United States); Travis, Larry D. [NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 (United States); Yang, Ping [Department of Atmospheric Sciences, Texas A& M University, College Station, TX 77843 (United States); Zakharova, Nadezhda T. [Trinnovim LLC, 2880 Broadway, New York, NY 10025 (United States)


    of the first-principles formalism enabling accurate calculations of monochromatic and quasi-monochromatic scattering by static and randomly varying multiparticle groups. We illustrate how this general framework can be coupled with state-of-the-art computer solvers of the Maxwell equations and applied to direct modeling of electromagnetic scattering by representative random multi-particle groups with arbitrary packing densities. This first-principles modeling yields general physical insights unavailable with phenomenological approaches. We discuss how the first-order-scattering approximation, the radiative transfer theory, and the theory of weak localization of electromagnetic waves can be derived as immediate corollaries of the Maxwell equations for very specific and well-defined kinds of particulate medium. These recent developments confirm the mesoscopic origin of the radiative transfer, weak localization, and effective-medium regimes and help evaluate the numerical accuracy of widely used approximate modeling methodologies.

  2. Study of multiple scattering effects in heavy ion RBS

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Z.; O`Connor, D.J. [Newcastle Univ., NSW (Australia). Dept. of Physics


    Multiple scattering effect is normally neglected in conventional Rutherford Backscattering (RBS) analysis. The backscattered particle yield normally agrees well with the theory based on the single scattering model. However, when heavy incident ions are used such as in heavy ion Rutherford backscattering (HIRBS), or the incident ion energy is reduced, multiple scattering effect starts to play a role in the analysis. In this paper, the experimental data of 6MeV C ions backscattered from a Au target are presented. In measured time of flight spectrum a small step in front of the Au high energy edge is observed. The high energy edge of the step is about 3.4 ns ahead of the Au signal which corresponds to an energy {approx} 300 keV higher than the 135 degree single scattering energy. This value coincides with the double scattering energy of C ion undergoes two consecutive 67.5 degree scattering. Efforts made to investigate the origin of the high energy step observed lead to an Monte Carlo simulation aimed to reproduce the experimental spectrum on computer. As a large angle scattering event is a rare event, two consecutive large angle scattering is extremely hard to reproduce in a random simulation process. Thus, the simulation has not found a particle scattering into 130-140 deg with an energy higher than the single scattering energy. Obviously faster algorithms and a better physical model are necessary for a successful simulation. 16 refs., 3 figs.

  3. Scattering effects of machined optical surfaces (United States)

    Thompson, Anita Kotha


    Optical fabrication is one of the most labor-intensive industries in existence. Lensmakers use pitch to affix glass blanks to metal chucks that hold the glass as they grind it with tools that have not changed much in fifty years. Recent demands placed on traditional optical fabrication processes in terms of surface accuracy, smoothnesses, and cost effectiveness has resulted in the exploitation of precision machining technology to develop a new generation of computer numerically controlled (CNC) optical fabrication equipment. This new kind of precision machining process is called deterministic microgrinding. The most conspicuous feature of optical surfaces manufactured by the precision machining processes (such as single-point diamond turning or deterministic microgrinding) is the presence of residual cutting tool marks. These residual tool marks exhibit a highly structured topography of periodic azimuthal or radial deterministic marks in addition to random microroughness. These distinct topographic features give rise to surface scattering effects that can significantly degrade optical performance. In this dissertation project we investigate the scattering behavior of machined optical surfaces and their imaging characteristics. In particular, we will characterize the residual optical fabrication errors and relate the resulting scattering behavior to the tool and machine parameters in order to evaluate and improve the deterministic microgrinding process. Other desired information derived from the investigation of scattering behavior is the optical fabrication tolerances necessary to satisfy specific image quality requirements. Optical fabrication tolerances are a major cost driver for any precision optical manufacturing technology. The derivation and control of the optical fabrication tolerances necessary for different applications and operating wavelength regimes will play a unique and central role in establishing deterministic microgrinding as a preferred and a

  4. Microwave single-scattering properties of randomly oriented soft-ice hydrometeors

    Directory of Open Access Journals (Sweden)

    D. Casella


    Full Text Available Large ice hydrometeors are usually present in intense convective clouds and may significantly affect the upwelling radiances that are measured by satellite-borne microwave radiometers – especially, at millimeter-wavelength frequencies. Thus, interpretation of these measurements (e.g., for precipitation retrieval requires knowledge of the single scattering properties of ice particles. On the other hand, shape and internal structure of these particles (especially, the larger ones is very complex and variable, and therefore it is necessary to resort to simplifying assumptions in order to compute their single-scattering parameters.

    In this study, we use the discrete dipole approximation (DDA to compute the absorption and scattering efficiencies and the asymmetry factor of two kinds of quasi-spherical and non-homogeneous soft-ice particles in the frequency range 50–183 GHz. Particles of the first kind are modeled as quasi-spherical ice particles having randomly distributed spherical air inclusions. Particles of the second kind are modeled as random aggregates of ice spheres having random radii. In both cases, particle densities and dimensions are coherent with the snow hydrometeor category that is utilized by the University of Wisconsin – Non-hydrostatic Modeling System (UW-NMS cloud-mesoscale model. Then, we compare our single-scattering results for randomly-oriented soft-ice hydrometeors with corresponding ones that make use of: a effective-medium equivalent spheres, b solid-ice equivalent spheres, and c randomly-oriented aggregates of ice cylinders. Finally, we extend to our particles the scattering formulas that have been developed by other authors for randomly-oriented aggregates of ice cylinders.

  5. Organic random lasers in the weak-scattering regime

    CERN Document Server

    Polson, R C; 10.1103/PhysRevB.71.045205


    We used the ensemble-averaged power Fourier transform (PFT) of random laser emission spectra over the illuminated area to study random lasers with coherent feedback in four different disordered organic gain media in the weak scattering regime, where the light mean free path, l* is much larger than the emission wavelength. The disordered gain media include a pi -conjugated polymer film, an opal photonic crystal infiltrated with a laser dye (rhodamine 6G; R6G) having optical gain in the visible spectral range, a suspension of titania balls in R6G solution, and biological tissues such as chicken breast infiltrated with R6G. We show the existence of universality among the random resonators in each gain medium that we tested, in which at the same excitation intensity a dominant random cavity is excited in different parts of the sample. We show a second universality when scaling the average PFT of the four different media by l*; we found that the dominant cavity in each disordered gain medium scales with l *. The e...

  6. Direct Simulation of Multiple Scattering by Discrete Random Media Illuminated by Gaussian Beams (United States)

    Mackowski, Daniel W.; Mishchenko, Michael I.


    The conventional orientation-averaging procedure developed in the framework of the superposition T-matrix approach is generalized to include the case of illumination by a Gaussian beam (GB). The resulting computer code is parallelized and used to perform extensive numerically exact calculations of electromagnetic scattering by volumes of discrete random medium consisting of monodisperse spherical particles. The size parameters of the scattering volumes are 40, 50, and 60, while their packing density is fixed at 5%. We demonstrate that all scattering patterns observed in the far-field zone of a random multisphere target and their evolution with decreasing width of the incident GB can be interpreted in terms of idealized theoretical concepts such as forward-scattering interference, coherent backscattering (CB), and diffuse multiple scattering. It is shown that the increasing violation of electromagnetic reciprocity with decreasing GB width suppresses and eventually eradicates all observable manifestations of CB. This result supplements the previous demonstration of the effects of broken reciprocity in the case of magneto-optically active particles subjected to an external magnetic field.

  7. Numerically Exact Computer Simulations of Light Scattering by Densely Packed, Random Particulate Media (United States)

    Dlugach, Janna M.; Mishchenko, Michael I.; Liu, Li; Mackowski, Daniel W.


    Direct computer simulations of electromagnetic scattering by discrete random media have become an active area of research. In this progress review, we summarize and analyze our main results obtained by means of numerically exact computer solutions of the macroscopic Maxwell equations. We consider finite scattering volumes with size parameters in the range, composed of varying numbers of randomly distributed particles with different refractive indices. The main objective of our analysis is to examine whether all backscattering effects predicted by the low-density theory of coherent backscattering (CB) also take place in the case of densely packed media. Based on our extensive numerical data we arrive at the following conclusions: (i) all backscattering effects predicted by the asymptotic theory of CB can also take place in the case of densely packed media; (ii) in the case of very large particle packing density, scattering characteristics of discrete random media can exhibit behavior not predicted by the low-density theories of CB and radiative transfer; (iii) increasing the absorptivity of the constituent particles can either enhance or suppress typical manifestations of CB depending on the particle packing density and the real part of the refractive index. Our numerical data strongly suggest that spectacular backscattering effects identified in laboratory experiments and observed for a class of high-albedo Solar System objects are caused by CB.

  8. Spatial quantum correlations induced by random multiple scattering of quadrature squeezed light

    DEFF Research Database (Denmark)

    Lodahl, Peter


    The authors demonstrates that spatial quantum correlations are induced by multiple scattering of quadrature squeezed light through a random medium. As a consequence, light scattered along two different directions by the random medium will not be independent, but be correlated to an extent that ca...... only be described by a quantum mechanical theory for multiple scattering. The spatial quantum correlation is revealed in the fluctuations of the total intensity transmission or reflection through the multiple scattering medium.......The authors demonstrates that spatial quantum correlations are induced by multiple scattering of quadrature squeezed light through a random medium. As a consequence, light scattered along two different directions by the random medium will not be independent, but be correlated to an extent that can...

  9. Electromagnetic wave scattering in a two-layer anisotropic random medium (United States)

    Lee, J. K.; Kong, J. A.


    For electromagnetic wave propagation and scattering in an anisotropic random medium, the Dyson equation for the mean field and the Bethe-Salpeter equation for the correlation or the covariance of the field were derived. With the random permittivity expressed in a general anisotropic form, the bilocal and the nonlinear approximations are employed to solve the Dyson equation, and the ladder approximation to solve the Bethe-Salpeter equation. The mean dyadic Green's function for a two-layer anisotropic random medium with arbitrary three-dimensional correlation functions has been investigated with the zeroth-order solutions to the Dyson equation under the nonlinear approximation. The effective propagation constants are calculated for the four characteristic waves associated with the coherent vector fields, propagating in an anisotropic random-medium layer, which are the ordinary and extraordinary waves with upward- and downward-propagating vectors.

  10. Remarks on the Radiative Transfer Approach to Scattering of Electromagnetic Waves in Layered Random Media (United States)



  11. Scattering Effects in Proximity Effect Tunneling Spectroscopy. (United States)

    Gai, Wei

    PETS (Proximity Effect Tunneling Spectroscopy) technique has been applied to Niobium/Yttrium and Niobium/Lutetium bilayers. We have determined electron - phonon interaction parameter lambda_{rm e -ph} is 0.55 for Yttrium and 0.67 for Lutetium. Spin fluctuations parameter lambda_{ rm S} is 0.20 for Yttrium and 0.33 for Lutetium. We found that the large spin fluctuations in Yttrium and Lutetium has responsibility to the absence of superconductivity in them. Our results have given a reasonable explanation of high superconducting transition temperature in them under high pressure. The large reflection coefficient and strong diffuse scattering at Nb/Y and Nb/Lu interface has been discovered and it should have strong influence on the transport properties of metallic superlattices. From the modeling study of elastic scattering in proximity effect tunnel junctions, we have explained why some conventional made high {rm T_{C}} superconducting tunnel junctions give ideal like characteristics in the gap region but variable strength phonon structures in the phonon region.

  12. Custom-tailored spatial mode sorting by controlled random scattering (United States)

    Fickler, Robert; Ginoya, Manit; Boyd, Robert W.


    The need to increase data transfer rates constitutes a key challenge in modern information-driven societies. Taking advantage of the transverse spatial modes of light to encode more information is a promising avenue for both classical and quantum photonics. However, to ease access to the encoded information, it is essential to be able to sort spatial modes into different output channels. Here, we introduce a way to customize the sorting of arbitrary spatial light modes. Our method relies on the high degree of control over random scattering processes by preshaping of the phase structure of the incident light. We demonstrate experimentally that various sets of modes, irrespective of their specific modal structure, can be transformed to a broad range of output channel arrangements. Thus, our method enables full access to all of the information encoded in the transverse structure of the field; for example, azimuthal and radial modes. We also demonstrate that coherence is retained in this complex mode transformation, which opens up applications in quantum and classical information science.

  13. Products of rectangular random matrices: Singular values and progressive scattering (United States)

    Akemann, Gernot; Ipsen, Jesper R.; Kieburg, Mario


    We discuss the product of M rectangular random matrices with independent Gaussian entries, which have several applications, including wireless telecommunication and econophysics. For complex matrices an explicit expression for the joint probability density function is obtained using the Harish-Chandra-Itzykson-Zuber integration formula. Explicit expressions for all correlation functions and moments for finite matrix sizes are obtained using a two-matrix model and the method of biorthogonal polynomials. This generalizes the classical result for the so-called Wishart-Laguerre Gaussian unitary ensemble (or chiral unitary ensemble) at M=1, and previous results for the product of square matrices. The correlation functions are given by a determinantal point process, where the kernel can be expressed in terms of Meijer G-functions. We compare the results with numerical simulations and known results for the macroscopic level density in the limit of large matrices. The location of the end points of support for the latter are analyzed in detail for general M. Finally, we consider the so-called ergodic mutual information, which gives an upper bound for the spectral efficiency of a MIMO communication channel with multifold scattering.

  14. Scattering of electromagnetic waves from a periodic surface with random roughness (United States)

    Yueh, H. A.; Shin, R. T.; Kong, J. A.


    Equations for the scattering of electromagnetic waves from a randomly perturbed periodic surface have been formulated using the extended boundary condition method and solved using the small perturbation method. Surface currents and scattered fields are solved for up to the second order. The results indicate that as the correlation length of the random roughness increases, the bistatic scattering patterns of the scattered fields show several beams associated with each Bragg diffraction direction of the periodic surface. The beam shape becomes broader with smaller correlation length. Results obtained using the Kirchhoff approximation are found to agree well with the present results for the hh and vv polarized backscattering coefficients for small angles of incidence.

  15. Inverse random source scattering for the Helmholtz equation in inhomogeneous media (United States)

    Li, Ming; Chen, Chuchu; Li, Peijun


    This paper is concerned with an inverse random source scattering problem in an inhomogeneous background medium. The wave propagation is modeled by the stochastic Helmholtz equation with the source driven by additive white noise. The goal is to reconstruct the statistical properties of the random source such as the mean and variance from the boundary measurement of the radiated random wave field at multiple frequencies. Both the direct and inverse problems are considered. We show that the direct problem has a unique mild solution by a constructive proof. For the inverse problem, we derive Fredholm integral equations, which connect the boundary measurement of the radiated wave field with the unknown source function. A regularized block Kaczmarz method is developed to solve the ill-posed integral equations. Numerical experiments are included to demonstrate the effectiveness of the proposed method.

  16. Leaf-shape effects in electromagnetic wave scattering from vegetation (United States)

    Karam, Mostafa A.; Fung, Adrian K.


    A vegetation medium is modeled as a half-space of randomly distributed and oriented leaves of arbitrary shape. In accordance with the first-order radiative transfer theory, the backscattering coefficient for such a half-space is expressed in terms of the scattering amplitudes. For disc- or needle-shaped leaves, the generalized Rayleigh-Gans approximation is used to calculate the scattering amplitudes. This approach is valid for leaf dimensions up to the size of the incident wavelength. To examine the leaf-shape effect, elliptic discs are used to model deciduous leaves, and needles are used to model coniferous leaves. The differences between the scattering characteristics of leaves of different shapes are illustrated numerically for various orientations, frequencies, and incidence angles. It is found that the scattering characteristics of elliptic disc-shaped leaves are sensitive to the three angles of orientation and disc ellipticity. In general, both like and cross polarizations may be needed to differentiate the difference in scattering due to the shapes of the leaves.

  17. Broken Cloud Field Longwave-Scattering Effects. (United States)

    Takara, E. E.; Ellingson, R. G.


    Throughout most of the shortwave spectrum, atmospheric gases do not absorb the abundant amount of incoming solar radiation. The shortwave-scattering albedo of clouds is very large. The combination of large amounts of incoming solar radiation, low gaseous absorptivity, and large cloud-scattering albedo enables clouds at one level of the atmosphere to affect the shortwave radiative transfer at all other atmospheric levels. Absorption by atmospheric gases is much stronger in the longwave. This localizes the effects of clouds in the longwave. Since longwave absorption is weakest in the window region (8-12 m), cloud effects there will have the greatest chance of propagating to other levels of the atmosphere. In partially overcast conditions, individual cloud geometry and optical properties are important factors. Longwave calculations of most GCMs ignore individual cloud geometry. For liquid water clouds, the optical properties of clouds are also ignored.Previous work in the window region by Takara and Ellingson considered opaque clouds with no absorption or emission by atmospheric gases. Under those conditions, the effect of cloud scattering was comparable to cloud geometry. In this work, the comparison of longwave scattering and geometric effects in the window region is improved by including partially transparent clouds and adding absorption and emission by atmospheric gases. The results show that for optically thick water clouds, it is sufficient to model the geometry; scattering can be neglected. The window region errors are less than 5 W m2 for fluxes and 0.05 K day1 for heating rates. The flat-plate approximation worked for ice clouds; the window region flux errors are less than 3 W m2 with heating rate errors less than 0.05 K day1.

  18. Resonant Scattering of Acoustic Phonons by Randomly Distributed Two-Level Systems (United States)

    Kayanuma, Yosuke; Yamada, Hiroshi; Tanaka, Satoshi


    A Green function formalism is developed for the resonant scattering of acoustic phonons by randomly distributed two-level systems. The randomness is treated by the coherent potential approximation. The theory reproduces the Jacobsen-Stevens dispersion law in the dense limit of the concentration of the two-level system and the results obtained so far by the average t-matrix approximation in the dilute limit. The gradual change of the character of the resonantly scattered phonons as the concentration is varied is investigated through the calculation of various quantities such as the phonon density of states, the neutron scattering cross sections and the sound velocity.

  19. Effective Tree Scattering at L-Band (United States)

    Kurum, Mehmet; ONeill, Peggy E.; Lang, Roger H.; Joseph, Alicia T.; Cosh, Michael H.; Jackson, Thomas J.


    For routine microwave Soil Moisture (SM) retrieval through vegetation, the tau-omega [1] model [zero-order Radiative Transfer (RT) solution] is attractive due to its simplicity and eases of inversion and implementation. It is the model used in baseline retrieval algorithms for several planned microwave space missions, such as ESA's Soil Moisture Ocean Salinity (SMOS) mission (launched November 2009) and NASA's Soil Moisture Active Passive (SMAP) mission (to be launched 2014/2015) [2 and 3]. These approaches are adapted for vegetated landscapes with effective vegetation parameters tau and omega by fitting experimental data or simulation outputs of a multiple scattering model [4-7]. The model has been validated over grasslands, agricultural crops, and generally light to moderate vegetation. As the density of vegetation increases, sensitivity to the underlying SM begins to degrade significantly and errors in the retrieved SM increase accordingly. The zero-order model also loses its validity when dense vegetation (i.e. forest, mature corn, etc.) includes scatterers, such as branches and trunks (or stalks in the case of corn), which are large with respect to the wavelength. The tau-omega model (when applied over moderately to densely vegetated landscapes) will need modification (in terms of form or effective parameterization) to enable accurate characterization of vegetation parameters with respect to specific tree types, anisotropic canopy structure, presence of leaves and/or understory. More scattering terms (at least up to first-order at L-band) should be included in the RT solutions for forest canopies [8]. Although not really suitable to forests, a zero-order tau-omega model might be applied to such vegetation canopies with large scatterers, but that equivalent or effective parameters would have to be used [4]. This requires that the effective values (vegetation opacity and single scattering albedo) need to be evaluated (compared) with theoretical definitions of

  20. Light scattering and random lasing in aqueous suspensions of hexagonal boron nitride nanoflakes (United States)

    O’Brien, S. A.; Harvey, A.; Griffin, A.; Donnelly, T.; Mulcahy, D.; Coleman, J. N.; Donegan, J. F.; McCloskey, D.


    Liquid phase exfoliation allows large scale production of 2D materials in solution. The particles are highly anisotropic and strongly scatter light. While spherical particles can be accurately and precisely described by a single parameter—the radius, 2D nanoflakes, however, cannot be so easily described. We investigate light scattering in aqueous solutions of 2D hexagonal boron nitride nanoflakes in the single and multiple scattering regimes. In the single scattering regime, the anisotropic 2D materials show a much stronger depolarization of light when compared to spherical particles of similar size. In the multiple scattering regime, the scattering as a function of optical path for hexagonal boron nitride nanoflakes of a given lateral length was found to be qualitatively equivalent to scattering from spheres with the same diameter. We also report the presence of random lasing in high concentration suspensions of aqueous h-BN mixed with Rhodamine B dye. The h-BN works as a scattering agent and Rhodamine B as a gain medium for the process. We observed random lasing at 587 nm with a threshold energy of 0.8 mJ.

  1. Investigation of the effect of scattering agent and scattering albedo on modulated light propagation in water. (United States)

    Mullen, Linda; Alley, Derek; Cochenour, Brandon


    A recent paper described experiments completed to study the effect of scattering on the propagation of modulated light in laboratory tank water [Appl. Opt.48, 2607 (2009)APOPAI0003-693510.1364/AO.48.002607]. Those measurements were limited to a specific scattering agent (Maalox antacid) with a fixed scattering albedo (0.95). The purpose of this paper is to study the effects of different scattering agents and scattering albedos on modulated light propagation in water. The results show that the scattering albedo affects the number of attenuation lengths that the modulated optical signal propagates without distortion, while the type of scattering agent affects the degree to which the modulation is distorted with increasing attenuation length. © 2011 Optical Society of America

  2. Scattering unitarity with effective dimension-6 operators (United States)

    Ghosh, Swagata; Islam, Rashidul; Kundu, Anirban


    The effects of physics beyond the Standard Model (SM) may be parametrized by a set of higher-dimensional operators leading to an effective theory. The introduction of these operators makes the theory nonrenormalizable, and one may reasonably expect a violation of unitarity in 2\\to 2 scattering processes, depending on the values of the Wilson coefficients (WC) of the higher dimensional operators. Bounds on these coefficients may be obtained from demanding that there be no such unitarity violation below the scale of the effective theory. We show, at the lowest level, how the new operators affect the scattering amplitudes with longitudinal gauge bosons, scalars, and t\\overline{t} in the final state, and find that one may expect a violation of unitarity even at the LHC energies with small values of some of the new WC. For most of the others, such a violation needs large coefficients, indicating nonperturbative physics for the ultraviolet-complete theory, although a proper treatment necessitates the inclusion of even higher-dimensional operators. However, deviations from the SM expectations may be observed with even smaller values for these coefficients. We find that {WW}\\to {WW}, {WW}\\to {ZZ}, and {ZZ}\\to {hh} scatterings are the best possible channels to probe unitarity violations.

  3. Scattering Effect on Anomalous Hall Effect in Ferromagnetic Transition Metals

    KAUST Repository

    Zhang, Qiang


    The anomalous Hall effect (AHE) has been discovered for over a century, but its origin is still highly controversial theoretically and experimentally. In this study, we investigated the scattering effect on the AHE for both exploring the underlying physics and technical applications. We prepared Cox(MgO)100-x granular thin films with different Co volume fraction (34≤≤100) and studied the interfacial scattering effect on the AHE. The STEM HAADF images confirmed the inhomogeneous granular structure of the samples. As decreases from 100 to 34, the values of longitudinal resistivity () and anomalous Hall resistivity (AHE) respectively increase by about four and three orders in magnitude. The linear scaling relation between the anomalous Hall coefficient () and the measured at 5 K holds in both the as-prepared and annealed samples, which suggests a skew scattering dominated mechanism in Cox(MgO)100-x granular thin films. We prepared (Fe36//Au12/), (Ni36//Au12/) and (Ta12//Fe36/) multilayers to study the interfacial scattering effect on the AHE. The multilayer structures were characterized by the XRR spectra and TEM images of cross-sections. For the three serials of multilayers, both the and AHE increase with , which clearly shows interfacial scattering effect. The intrinsic contribution decreases with increases in the three serials of samples, which may be due to the crystallinity decaying or the finite size effect. In the (Fe36//Au12/) samples, the side-jump contribution increases with , which suggests an interfacial scattering-enhanced side jump. In the (Ni36//Au12/) samples, the side-jump contribution decreases with increases, which could be explained by the opposite sign of the interfacial scattering and grain boundary scattering contributed side jump. In the (Ta12//Fe36/) multilayers, the side-jump contribution changed from negative to positive, which is also because of the opposite sign of the interfacial scattering and grain boundary scattering

  4. Diffusely scattered and transmitted elastic waves by random rough solid-solid interfaces using an elastodynamic Kirchhoff approximation (United States)

    Shi, Fan; Lowe, Mike; Craster, Richard


    Elastic waves scattered by random rough interfaces separating two distinct media play an important role in modeling phonon scattering and impact upon thermal transport models, and are also integral to ultrasonic inspection. We introduce theoretical formulas for the diffuse field of elastic waves scattered by, and transmitted across, random rough solid-solid interfaces using the elastodynamic Kirchhoff approximation. The new formulas are validated by comparison with numerical Monte Carlo simulations, for a wide range of roughness (rms σ ≤λ /3 , correlation length λ0≥ wavelength λ ), demonstrating a significant improvement over the widely used small-perturbation approach, which is valid only for surfaces with small rms values. Physical analysis using the theoretical formulas derived here demonstrates that increasing the rms value leads to a considerable change of the scattering patterns for each mode. The roughness has different effects on the reflection and the transmission, with a strong dependence on the material properties. In the special case of a perfect match of the wave speed of the two solid media, the transmission is the same as the case for a flat interface. We pay particular attention to scattering in the specular direction, often used as an observable quantity, in terms of the roughness parameters, showing a peak at an intermediate value of rms; this rms value coincides with that predicted by the Rayleigh parameter.

  5. Errors due to random noise in velocity measurement using incoherent-scatter radar

    Directory of Open Access Journals (Sweden)

    P. J. S. Williams

    Full Text Available The random-noise errors involved in measuring the Doppler shift of an 'incoherent-scatter' spectrum are predicted theoretically for all values of Te/Ti from 1.0 to 3.0. After correction has been made for the effects of convolution during transmission and reception and the additional errors introduced by subtracting the average of the background gates, the rms errors can be expressed by a simple semi-empirical formula. The observed errors are determined from a comparison of simultaneous EISCAT measurements using an identical pulse code on several adjacent frequencies. The plot of observed versus predicted error has a slope of 0.991 and a correlation coefficient of 99.3%. The prediction also agrees well with the mean of the error distribution reported by the standard EISCAT analysis programme.

  6. Errors due to random noise in velocity measurement using incoherent-scatter radar

    Directory of Open Access Journals (Sweden)

    P. J. S. Williams


    Full Text Available The random-noise errors involved in measuring the Doppler shift of an 'incoherent-scatter' spectrum are predicted theoretically for all values of Te/Ti from 1.0 to 3.0. After correction has been made for the effects of convolution during transmission and reception and the additional errors introduced by subtracting the average of the background gates, the rms errors can be expressed by a simple semi-empirical formula. The observed errors are determined from a comparison of simultaneous EISCAT measurements using an identical pulse code on several adjacent frequencies. The plot of observed versus predicted error has a slope of 0.991 and a correlation coefficient of 99.3%. The prediction also agrees well with the mean of the error distribution reported by the standard EISCAT analysis programme.

  7. Dielectric effects on Thomson scattering in a relativistic magnetized plasma

    DEFF Research Database (Denmark)

    Bindslev, H.


    The effects of the dielectric properties of a relativistic magnetized plasma on the scattering of electromagnetic radiation by fluctuations in electron density are investigated. The origin of the density fluctuations is not considered. Expressions for the scattering cross-section and the scattered...

  8. Light scattering by small feldspar particles simulated using the Gaussian random sphere geometry

    NARCIS (Netherlands)

    Veihelmann, B.; Nousiainen, T.; Kahnert, M.; Zande, W.J. van der


    The single-scattering properties of Gaussian random spheres are calculated using the discrete dipole approximation. The ensemble of model particles is assumed to be representative for a feldspar dust sample that is characteristic for weakly absorbing irregularly shaped mineral aerosol. The

  9. Simulations of ultrasound propagation in random arrangements of elliptic scatterers: occurrence of two longitudinal waves. (United States)

    Mézière, Fabien; Muller, Marie; Dobigny, Blandine; Bossy, Emmanuel; Derode, Arnaud


    Ultrasound propagation in clusters of elliptic (two-dimensional) or ellipsoidal (three-dimensional) scatterers randomly distributed in a fluid is investigated numerically. The essential motivation for the present work is to gain a better understanding of ultrasound propagation in trabecular bone. Bone microstructure exhibits structural anisotropy and multiple wave scattering. Some phenomena remain partially unexplained, such as the propagation of two longitudinal waves. The objective of this study was to shed more light on the occurrence of these two waves, using finite-difference simulations on a model medium simpler than bone. Slabs of anisotropic, scattering media were randomly generated. The coherent wave was obtained through spatial and ensemble-averaging of the transmitted wavefields. When varying relevant medium parameters, four of them appeared to play a significant role for the observation of two waves: (i) the solid fraction, (ii) the direction of propagation relatively to the scatterers orientation, (iii) the ability of scatterers to support shear waves, and (iv) a continuity of the solid matrix along the propagation. These observations are consistent with the hypothesis that fast waves are guided by the locally plate/bar-like solid matrix. If confirmed, this interpretation could significantly help developing approaches for a better understanding of trabecular bone micro-architecture using ultrasound.

  10. Electronic transport in a one-dimensional random array of scatterers

    CERN Document Server

    Filinov, V S; Varga, I; Meier, T; Bonitz, M; Fortov, V E; Koch, S W


    The quantum dynamics of an ensemble of interacting electrons in an array of random scatterers is treated using a new numerical approach for the calculation of average values of quantum operators and time correlation functions in the Wigner representation. This approach combines both molecular dynamics and Monte Carlo methods and computes numerical traces and spectra of the relevant dynamical quantities such as momentum-momentum correlation functions and spatial dispersions. Considering, as an application, a system with fixed scatterers, the results clearly demonstrate that the many-particle interaction between the electrons can lead to an enhancement of the conductivity at intermediate densities.

  11. Effect of scattering on coherent anti-Stokes Raman scattering (CARS) signals. (United States)

    Ranasinghesagara, Janaka C; De Vito, Giuseppe; Piazza, Vincenzo; Potma, Eric O; Venugopalan, Vasan


    We develop a computational framework to examine the factors responsible for scattering-induced distortions of coherent anti-Stokes Raman scattering (CARS) signals in turbid samples. We apply the Huygens-Fresnel wave-based electric field superposition (HF-WEFS) method combined with the radiating dipole approximation to compute the effects of scattering-induced distortions of focal excitation fields on the far-field CARS signal. We analyze the effect of spherical scatterers, placed in the vicinity of the focal volume, on the CARS signal emitted by different objects (2μm diameter solid sphere, 2μm diameter myelin cylinder and 2μm diameter myelin tube). We find that distortions in the CARS signals arise not only from attenuation of the focal field but also from scattering-induced changes in the spatial phase that modifies the angular distribution of the CARS emission. Our simulations further show that CARS signal attenuation can be minimized by using a high numerical aperture condenser. Moreover, unlike the CARS intensity image, CARS images formed by taking the ratio of CARS signals obtained using x- and y-polarized input fields is relatively insensitive to the effects of spherical scatterers. Our computational framework provide a mechanistic approach to characterizing scattering-induced distortions in coherent imaging of turbid media and may inspire bottom-up approaches for adaptive optical methods for image correction.

  12. Multiple Volume Scattering in Random Media and Periodic Structures with Applications in Microwave Remote Sensing and Wave Functional Materials (United States)

    Tan, Shurun

    The objective of my research is two-fold: to study wave scattering phenomena in dense volumetric random media and in periodic wave functional materials. For the first part, the goal is to use the microwave remote sensing technique to monitor water resources and global climate change. Towards this goal, I study the microwave scattering behavior of snow and ice sheet. For snowpack scattering, I have extended the traditional dense media radiative transfer (DMRT) approach to include cyclical corrections that give rise to backscattering enhancements, enabling the theory to model combined active and passive observations of snowpack using the same set of physical parameters. Besides DMRT, a fully coherent approach is also developed by solving Maxwell's equations directly over the entire snowpack including a bottom half space. This revolutionary new approach produces consistent scattering and emission results, and demonstrates backscattering enhancements and coherent layer effects. The birefringence in anisotropic snow layers is also analyzed by numerically solving Maxwell's equation directly. The effects of rapid density fluctuations in polar ice sheet emission in the 0.5˜2.0 GHz spectrum are examined using both fully coherent and partially coherent layered media emission theories that agree with each other and distinct from incoherent approaches. For the second part, the goal is to develop integral equation based methods to solve wave scattering in periodic structures such as photonic crystals and metamaterials that can be used for broadband simulations. Set upon the concept of modal expansion of the periodic Green's function, we have developed the method of broadband Green's function with low wavenumber extraction (BBGFL), where a low wavenumber component is extracted and results a non-singular and fast-converging remaining part with simple wavenumber dependence. We've applied the technique to simulate band diagrams and modal solutions of periodic structures, and to

  13. Robert R. Wilson Prize I: Intrabeam Scattering and Touschek Effect (United States)

    Piwinski, Anton


    Intrabeam scattering and the Touschek effect are explained and compared. Especially intrabeam scattering plays an important role in colliders and synchrotron radiation sources where it limits the beam lifetime and the brightness,respectively. A short history of the consequences of both effects in different accelerators is given. An invariant due to intrabeam scattering is discussed which shows that only below transition energy a stable particle distribution is possible whereas above transition energy a stable distribution cannot exist.

  14. Novel Quantum Effects in Light Scattering from Cold Trapped Atoms (United States)

    Orlowski, A.; Gajda, M.; Krekora, P.; Glauber, R. J.; Mostowski, J.

    Both far off-resonance and resonant scattering of light from single atoms trapped by 3D harmonic potentials has thoroughly been studied. Novel effects are predicted for different physical regimes. We have shown that dynamics of the atomic center-of-mass strongly influences the scattering cross section. Possibility of using spectrum of the scattered light in far-off-resonance regime to nondestructively measure the temperature of ultracold atoms is advocated: off-resonance scattering can be used as an `optical thermometer'. The realistic Compton-like regime in resonant scattering has been investigated in detail. Another interesting quantum effect in resonant regime, which has not been discussed here due to the lack of space, is the time resolved scattering, showing up when the atom can remain in the excited state long enough to make many trips back and forth in the trap before emitting a photon. The possibility of the experimental observation of the predicted effects is now being scrutinized.

  15. Evaluation of the loading effect on the optically modulated scatterer

    NARCIS (Netherlands)

    Sowa, Andrzej E.; Vogt-Ardatjew, R.A.


    In this paper, the evaluation of the loading effect in the Optically Modulated Scatterer has been presented. A chosen location in the vicinity of a pyramidal absorber has been analyzed. The loading effect as a function of the distance between the scatterer and the absorber has been investigated.

  16. Statistics of time delay and scattering correlation functions in chaotic systems. I. Random matrix theory (United States)

    Novaes, Marcel


    We consider the statistics of time delay in a chaotic cavity having M open channels, in the absence of time-reversal invariance. In the random matrix theory approach, we compute the average value of polynomial functions of the time delay matrix Q = - iħS†dS/dE, where S is the scattering matrix. Our results do not assume M to be large. In a companion paper, we develop a semiclassical approximation to S-matrix correlation functions, from which the statistics of Q can also be derived. Together, these papers contribute to establishing the conjectured equivalence between the random matrix and the semiclassical approaches.

  17. Statistics of time delay and scattering correlation functions in chaotic systems. I. Random matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Novaes, Marcel [Instituto de Física, Universidade Federal de Uberlândia, Ave. João Naves de Ávila, 2121, Uberlândia, MG 38408-100 (Brazil)


    We consider the statistics of time delay in a chaotic cavity having M open channels, in the absence of time-reversal invariance. In the random matrix theory approach, we compute the average value of polynomial functions of the time delay matrix Q = − iħS{sup †}dS/dE, where S is the scattering matrix. Our results do not assume M to be large. In a companion paper, we develop a semiclassical approximation to S-matrix correlation functions, from which the statistics of Q can also be derived. Together, these papers contribute to establishing the conjectured equivalence between the random matrix and the semiclassical approaches.

  18. Modeling of Electromagnetic Scattering by Discrete and Discretely Heterogeneous Random Media by Using Numerically Exact Solutions of the Maxwell Equations (United States)

    Dlugach, Janna M.; Mishchenko, Michael I.


    In this paper, we discuss some aspects of numerical modeling of electromagnetic scattering by discrete random medium by using numerically exact solutions of the macroscopic Maxwell equations. Typical examples of such media are clouds of interstellar dust, clouds of interplanetary dust in the Solar system, dusty atmospheres of comets, particulate planetary rings, clouds in planetary atmospheres, aerosol particles with numerous inclusions and so on. Our study is based on the results of extensive computations of different characteristics of electromagnetic scattering obtained by using the superposition T-matrix method which represents a direct computer solver of the macroscopic Maxwell equations for an arbitrary multisphere configuration. As a result, in particular, we clarify the range of applicability of the low-density theories of radiative transfer and coherent backscattering as well as of widely used effective-medium approximations.

  19. Surface roughness and grain boundary scattering effects on the electrical conductivity of thin films

    NARCIS (Netherlands)

    Palasantzas, George


    In this work, we investigate surface/interface roughness and grain boundary scattering effects on the electrical conductivity of polycrystalline thin films in the Born approximation. We assume for simplicity a random Gaussian roughness convoluted with a domain size distribution ~e^-πr^2/ζ^2 to

  20. Universal dimer–dimer scattering in lattice effective field theory

    Directory of Open Access Journals (Sweden)

    Serdar Elhatisari


    Full Text Available We consider two-component fermions with short-range interactions and large scattering length. This system has universal properties that are realized in several different fields of physics. In the limit of large fermion–fermion scattering length aff and zero-range interaction, all properties of the system scale proportionally with aff. For the case with shallow bound dimers, we calculate the dimer–dimer scattering phase shifts using lattice effective field theory. We extract the universal dimer–dimer scattering length add/aff=0.618(30 and effective range rdd/aff=−0.431(48. This result for the effective range is the first calculation with quantified and controlled systematic errors. We also benchmark our methods by computing the fermion–dimer scattering parameters and testing some predictions of conformal scaling of irrelevant operators near the unitarity limit.

  1. Light scattering optimization of chitin random network in ultrawhite beetle scales (United States)

    Utel, Francesco; Cortese, Lorenzo; Pattelli, Lorenzo; Burresi, Matteo; Vignolini, Silvia; Wiersma, Diederik


    Among the natural white colored photonics structures, a bio-system has become of great interest in the field of disordered optical media: the scale of the white beetle Chyphochilus. Despite its low thickness, on average 7 μm, and low refractive index, this beetle exhibits extreme high brightness and unique whiteness. These properties arise from the interaction of light with a complex network of chitin nano filaments embedded in the interior of the scales. As it's been recently claimed, this could be a consequence of the peculiar morphology of the filaments network that, by means of high filling fraction (0.61) and structural anisotropy, optimizes the multiple scattering of light. We therefore performed a numerical analysis on the structural properties of the chitin network in order to understand their role in the enhancement of the scale scattering intensity. Modeling the filaments as interconnected rod shaped scattering centers, we numerically generated the spatial coordinates of the network components. Controlling the quantities that are claimed to play a fundamental role in the brightness and whiteness properties of the investigated system (filling fraction and average rods orientation, i.e. the anisotropy of the ensemble of scattering centers), we obtained a set of customized random networks. FDTD simulations of light transport have been performed on these systems, observing high reflectance for all the visible frequencies and proving the implemented algorithm to numerically generate the structures is suitable to investigate the dependence of reflectance by anisotropy.

  2. Effect of Scatterering on Coherent Anti-Stokes Raman Scattering (CARS) signals

    CERN Document Server

    Ranasinghesagara, Janaka C; Piazza, Vincenzo; Potma, Eric O; Venugopalan, Vasan


    We develop a computational framework to examine the factors responsible for scattering-induced distortions of coherent anti-Stokes Raman scattering (CARS) signals in turbid samples. We use the Huygens-Fresnel Wave-based Electric Field Superposition (HF-WEFS) method combined with the radiating dipole approximation to compute the effects of scattering-induced distortions of focal excitation fields on the far-field CARS signal. We analyze the effect of spherical scatterers, placed in the vicinity of the focal volume, on the CARS signal emitted by different objects (2{\\mu}m diameter solid sphere, 2{\\mu}m diameter myelin cylinder and 2{\\mu}m diameter myelin tube). We find that distortions in the CARS signals arise not only from attenuation of the focal field but also from scattering-induced changes in the spatial phase that modifies the angular distribution of the CARS emission. Our simulations further show that CARS signal attenuation can be minimized by using a high numerical aperture condenser. Moreover, unlike...

  3. Polarized multiple scattering effect in Qweak (United States)

    Gal, Ciprian


    The Qweak experiment has measured the weak charge of the proton to unprecedented precision. In order to achieve this, all possible sources of systematic uncertainty had to be carefully controlled. This talk will present the work underpinning one of the leading systematic uncertainties in the measurement. Multiple scattering of transversely polarized electrons in the lead pre-radiator produced an additional asymmetry in the quartz integrating detectors. Analyzing powers inside the lead corresponding to Mott scattering and a two photon exchange model were implemented in a Geant4 simulation. A correction based on the physical differences between the left half and the right half of each Qweak detector was obtained. Potential implications to other parity violating experiments will be discussed.

  4. Ray effect and false scattering in the discrete ordinates method

    Energy Technology Data Exchange (ETDEWEB)

    Chai, J.C.; Patankar, S.V. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Mechanical Engineering; Lee, H.S. [NASA, Cleveland, OH (United States). Lewis Research Center


    A discussion on the ray effect and false scattering occurring in discrete ordinates solution of the radiative transfer equation is presented in this article. Ray effect arises from the approximation of a continuously varying angular nature of radiation by a specified set of discrete angular directions. It is independent of the spatial discretization practice. False scattering, on the other hand, is a consequence of the spatial discretization practice and is independent of the angular discretization practice. In multidimensional computations, when a beam is not aligned with the grid line, false scattering smears the radiative intensity field. It reduces the appearance of unwanted bumps, but does not eliminate ray effect. An inappropriate view of false scattering is also presented. Four sample problems are used to explain these two effects.

  5. Condition for invariant spectrum of an electromagnetic wave scattered from an anisotropic random media. (United States)

    Li, Jia; Wu, Pinghui; Chang, Liping


    Within the accuracy of the first-order Born approximation, sufficient conditions are derived for the invariance of spectrum of an electromagnetic wave, which is generated by the scattering of an electromagnetic plane wave from an anisotropic random media. We show that the following restrictions on properties of incident fields and the anisotropic media must be simultaneously satisfied: 1) the elements of the dielectric susceptibility matrix of the media must obey the scaling law; 2) the spectral components of the incident field are proportional to each other; 3) the second moments of the elements of the dielectric susceptibility matrix of the media are inversely proportional to the frequency.

  6. Broadband diffuse terahertz wave scattering by flexible metasurface with randomized phase distribution. (United States)

    Zhang, Yin; Liang, Lanju; Yang, Jing; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian; Jin, Biaobing; Liu, Weiwei


    Suppressing specular electromagnetic wave reflection or backward radar cross section is important and of broad interests in practical electromagnetic engineering. Here, we present a scheme to achieve broadband backward scattering reduction through diffuse terahertz wave reflection by a flexible metasurface. The diffuse scattering of terahertz wave is caused by the randomized reflection phase distribution on the metasurface, which consists of meta-particles of differently sized metallic patches arranged on top of a grounded polyimide substrate simply through a certain computer generated pseudorandom sequence. Both numerical simulations and experimental results demonstrate the ultralow specular reflection over a broad frequency band and wide angle of incidence due to the re-distribution of the incident energy into various directions. The diffuse scattering property is also polarization insensitive and can be well preserved when the flexible metasurface is conformably wrapped on a curved reflective object. The proposed design opens up a new route for specular reflection suppression, and may be applicable in stealth and other technology in the terahertz spectrum.

  7. Analysis of multiple scattering effects in optical Doppler tomography

    DEFF Research Database (Denmark)

    Yura, H.T.; Thrane, L.; Andersen, Peter E.


    Optical Doppler tomography (ODT) combines Doppler velocimetry and optical coherence tomography (OCT) to obtain high-resolution cross-sectional imaging of particle flow velocity in scattering media such as the human retina and skin. Here, we present the results of a theoretical analysis of ODT where...... Doppler frequency spectrum. Thus, in the present analysis, the dependence of the mean and standard deviation of the Doppler shift on the scattering properties of the flowing medium are obtained. Taking the multiple scattering effects into account, we are able to explain previous measurements of depth...

  8. Evaluation of scatter effects on image quality for breast tomosynthesis (United States)

    Wu, Gang; Mainprize, James G.; Boone, John M.; Yaffe, Martin J.


    Digital breast tomosynthesis uses a limited number of low-dose x-ray projections to produce a three-dimensional (3D) tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scatter radiation on image quality for breast tomosynthesis. Generated by a Monte Carlo simulation method, scatter point spread functions (PSF) were convolved over the field of view (FOV) to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrated that in the absence of scatter reduction techniques, the scatter-to-primary ratio (SPR) levels for the average breast are quite high (~0.4 at the centre of mass), and increased with increased breast thickness and with larger FOV. Associated with such levels of x-ray scatter are cupping artifacts, as well as reduced accuracy in reconstruction values. The effect of x-ray scatter on the contrast, noise, and signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of tumour size. For example, the contrast in the reconstructed central slice of a tumour-like mass (14 mm in diameter) was degraded by 30% while the inaccuracy of the voxel value was 28%, and the reduction of SDNR was 60%. We have quantified the degree to which scatter degrades the image quality over a wide range of parameters, including x-ray beam energy, breast thickness, breast diameter, and breast composition. However, even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice is higher than that of conventional mammographic projection images acquired with a grid at an equivalent total exposure.

  9. Evaluation of scatter effects on image quality for breast tomosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Wu Gang; Mainprize, James G.; Boone, John M.; Yaffe, Martin J. [Imaging Research, Sunnybrook Health Sciences Centre, S-657, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada) and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Department of Radiology, X-ray Imaging Laboratory, U. C. Davis Medical Center, 4701 X Street, Sacramento, California 95817 and Department of Biomedical Engineering, University of California, Davis, California 95616 (United States); Imaging Research, Sunnybrook Health Sciences Centre, S-657, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada) and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada)


    Digital breast tomosynthesis uses a limited number (typically 10-20) of low-dose x-ray projections to produce a pseudo-three-dimensional volume tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scattered radiation on the image quality for breast tomosynthesis. In a simulation, scatter point spread functions generated by a Monte Carlo simulation method were convolved over the breast projection to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrate that in the absence of scatter reduction techniques, images will be affected by cupping artifacts, and there will be reduced accuracy of attenuation values inferred from the reconstructed images. The effect of x-ray scatter on the contrast, noise, and lesion signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of the tumor size. When a with-scatter reconstruction was compared to one without scatter for a 5 cm compressed breast, the following results were observed. The contrast in the reconstructed central slice image of a tumorlike mass (14 mm in diameter) was reduced by 30%, the voxel value (inferred attenuation coefficient) was reduced by 28%, and the SDNR fell by 60%. The authors have quantified the degree to which scatter degrades the image quality over a wide range of parameters relevant to breast tomosynthesis, including x-ray beam energy, breast thickness, breast diameter, and breast composition. They also demonstrate, though, that even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice are higher than those of conventional mammographic projection images acquired with a grid at an equivalent total exposure.

  10. Evaluation of scatter effects on image quality for breast tomosynthesis. (United States)

    Wu, Gang; Mainprize, James G; Boone, John M; Yaffe, Martin J


    Digital breast tomosynthesis uses a limited number (typically 10-20) of low-dose x-ray projections to produce a pseudo-three-dimensional volume tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scattered radiation on the image quality for breast tomosynthesis. In a simulation, scatter point spread functions generated by a Monte Carlo simulation method were convolved over the breast projection to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrate that in the absence of scatter reduction techniques, images will be affected by cupping artifacts, and there will be reduced accuracy of attenuation values inferred from the reconstructed images. The effect of x-ray scatter on the contrast, noise, and lesion signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of the tumor size. When a with-scatter reconstruction was compared to one without scatter for a 5 cm compressed breast, the following results were observed. The contrast in the reconstructed central slice image of a tumorlike mass (14 mm in diameter) was reduced by 30%, the voxel value (inferred attenuation coefficient) was reduced by 28%, and the SDNR fell by 60%. The authors have quantified the degree to which scatter degrades the image quality over a wide range of parameters relevant to breast tomosynthesis, including x-ray beam energy, breast thickness, breast diameter, and breast composition. They also demonstrate, though, that even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice are higher than those of conventional mammographic projection images acquired with a grid at an equivalent total exposure.

  11. Study of Electromagnetic Scattering From Material Object Doped Randomly With Thin Metallic Wires Using Finite Element Method (United States)

    Deshpande, Manohar D.


    A new numerical simulation method using the finite element methodology (FEM) is presented to study electromagnetic scattering due to an arbitrarily shaped material body doped randomly with thin and short metallic wires. The FEM approach described in many standard text books is appropriately modified to account for the presence of thin and short metallic wires distributed randomly inside an arbitrarily shaped material body. Using this modified FEM approach, the electromagnetic scattering due to cylindrical, spherical material body doped randomly with thin metallic wires is studied.

  12. Testing the Predictions of Random Matrix Theory in Low Loss Wave Chaotic Scattering Systems (United States)

    Yeh, Jen-Hao; Antonsen, Thomas; Ott, Edward; Anlage, Steven


    Wave chaos is a field where researchers apply random matrix theory (RMT) to predict the statistics of wave properties in complicated wave scattering systems. The RMT predictions have successfully demonstrated universality of the distributions of these wave properties, which only depend on the loss parameter of the system and the physical symmetry. Examination of these predictions in very low loss systems is interesting because extreme limits for the distribution functions and other predictions are encountered. Therefore, we use a wave-chaotic superconducting cavity to establish a low loss environment and test RMT predictions, including the statistics of the scattering (S) matrix and the impedance (Z) matrix, the universality (or lack thereof) of the Z- and S-variance ratios, and the statistics of the proper delay times of the Wigner-Smith time-delay matrix. We have applied an in-situ microwave calibration method (Thru-Reflection-Line method) to calibrate the cryostat system, and we also applied the random coupling model to remove the system-specific features. Our experimental results of different properties agree with the RMT predictions. This work is funded by the ONR/Maryland AppEl Center Task A2 (contract No. N000140911190), the AFOSR under grant FA95500710049, and Center for Nanophysics and Advanced Materials.

  13. Effects of finite laser coherence in quasielastic multiple scattering (United States)

    Bellini, T.; Glaser, M. A.; Clark, N. A.; Degiorgio, V.


    We have studied the amplitude and temporal correlations of intensity fluctuations of multiply scattered light transmitted through a colloidal suspension. When the coherence length lc of the incident light becomes comparable to the width of the probability distribution of photon-path lengths, both the amplitude and dynamics of intensity fluctuations become functions of lc. In this article we present a simple theory that relates these coherence effects to the photon path-length distribution P(L). We have tested this theory using P(L) calculated from computer simulations and from the diffusion approximation, and find that our theory qualitatively accounts for the observed dependences on coherence length. Our results indicate when the effects of finite laser coherence must be taken into account in quasielastic multiple scattering. In the few-scattering regime of quasielastic multiple scattering, we find that the intensity autocorrelation function generally has a stretched-exponential form, and we discuss the origin of this behavior.

  14. Evaluation of scatter effects on image quality for breast tomosynthesis


    Wu, Gang; Mainprize, James G.; Boone, John M.; Yaffe, Martin J.


    Digital breast tomosynthesis uses a limited number (typically 10–20) of low-dose x-ray projections to produce a pseudo-three-dimensional volume tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scattered radiation on the image quality for breast tomosynthesis. In a simulation, scatter point spread functions generated by a Monte Carlo simulation method were convolved over the breast projection to estimate the distribution...

  15. Effect of anisotropic scattering in neutronics analysis of BWR assembly

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Toshikazu [Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0571 (Japan)]. E-mail:; Okamoto, Toshiki [Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0571 (Japan); Inoue, Akira [Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0571 (Japan); Kosaka, Shinya [TEPCO Systems Corporation, 2-37-28 Eitai, Koutou-ku, Tokyo 135-0034 (Japan); Ikeda, Hideaki [TEPCO Systems Corporation, 2-37-28 Eitai, Koutou-ku, Tokyo 135-0034 (Japan)


    The anisotropic scattering effect to keff is studied for UO{sub 2} and MOX fueled BWR assemblies. The anisotropic scattering effect increases the assembly k {sub {infinity}} by 0.44% {delta}k for the UO{sub 2} assembly with 0% void fraction, and by 0.21% {delta}k for the MOX assembly with 0% void fraction. This is because the anisotropic scattering effect flattens the intra-assembly thermal flux, and the absorption rate in the surrounding water gap is decreased, but the absorption rates in the MOX fuel rods are increased compared to the UO{sub 2} rods. Therefore, the total decrease in absorption rates in the UO{sub 2} assembly is relatively large, and the k {sub {infinity}} is increased in the UO{sub 2} assembly. The dependence of the anisotropic scattering effect on the void fraction is investigated, and the significant difference of 0.62% {delta}k/k is found for the 0% and the 80% void fractions. The BWR assemblies with Gd rods are also considered. Furthermore, the usefulness of the transport cross section is investigated, and it is found that the transport cross section gives reasonable anisotropic scattering effect, though not satisfactory.

  16. Orbital effects in cobaltites by neutron scattering (United States)

    Louca, Despina


    The orbital degree of freedom can play a central role in the physics of transition metal perovskite oxides because of its intricate coupling with other degrees of freedom such as spin, charge and lattice. In this talk the case of La1-xSrxCoO3 will be presented. Using elastic and inelastic neutron scattering, we investigated the thermal evolution of the local atomic structure and lattice dynamics in the pure sample and with the addition of charge carriers as the system crosses over from a paramagnetic insulator to a ferromagnetic metal. In LaCoO3, the thermal activation of the Co ions from a nonmagnetic ground state to an intermediate spin state gives rise to orbital degeneracy. This leads to Jahn-Teller distortions that are dynamical in nature. Doping stabilizes the intermediate spin configuration of the Co ions in the paramagnetic insulating phase. Evidence for local static Jahn-Teller distortions is observed but without long-range ordering. The size of the JT lattice is proportional to the amount of charge. However, with cooling to the metallic phase, static JT distortions disappear for x Louca and J. L. Sarrao, Phys. Rev. Lett. 91, 155501 (2003).

  17. ZnO nanorods as scatterers for random lasing emission from dye doped polymer films. (United States)

    Zhang, Dingke; Wang, Yanping; Ma, Dongge


    A random lasing emission from 4-(dicy-anomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped polystyrene (PS) thin films was realized by the scattering role of ZnO nanorods. The device was fabricated by spin-coating DCJTB doped PS on ZnO nanorods. The ZnO nanorods were grown on indium-tin-oxide (ITO) glass substrate by hydrothermal synthesis method. It can be seen that the device emits a resonance multimode peak at center wavelength of 630 nm with a mode line-width of less than 0.23 nm and exhibits threshold excitation intensity as low as 0.375 mJ pulse(-1) cm(-2). The agreement of the dependence of threshold pumped intensity on the excitation area with the random laser theory indicates that the lasing emission realized here is random laser. Our results demonstrate that the nanostructured ZnO nanorods are promising candidate as alternative sources of coherent light emission to realize organic lasers.

  18. Environmental effects on seabed object bistatic scattering classification. (United States)

    Fischell, Erin M; Schmidt, Henrik


    One of the factors that significantly affects bistatic scattering from seabed targets is bottom type. This factor has the potential to impact classification, as models that do not take bottom composition into account could improperly characterize target type, geometry, or material. This paper looks at the impact of bottom composition and self-burial on scattering from spherical and cylindrical targets in a 6.5 m deep environment with a mud and sand bottom. Sphere and cylinder scattering data from an autonomous underwater vehicle-based bistatic scattering experiment are compared to scattering simulation models with a range of bottom compositions and target burial increments. Three different sets of sediment parameters were tested. Correlation between the real and simulated data are then used to assess the similarity of each simulated scattering data set to the experiment data. Robustness to bottom composition in classification was then tested by training a model using simulated data and classifying experiment target data using a machine learning method for each environment type. Combined-environment classification models, composed of different ranges of mud depths and target burial increments, were shown to be effective at classifying the experiment data.

  19. Homogeneous illusion device exhibiting transformed and shifted scattering effect (United States)

    Mei, Jin-Shuo; Wu, Qun; Zhang, Kuang; He, Xun-Jun; Wang, Yue


    Based on the theory of transformation optics, a type of homogeneous illusion device exhibiting transformed and shifted scattering effect is proposed in this paper. The constitutive parameters of the proposed device are derived, and full-wave simulations are performed to validate the electromagnetic properties of transformed and shifted scattering effect. The simulation results show that the proposed device not only can visually shift the image of target in two dimensions, but also can visually transform the shape of target. It is expected that such homogeneous illusion device could possess potential applications in military camouflage and other field of electromagnetic engineering.

  20. Application of strong fluctuation random medium theory to scattering of electromagnetic waves from a half-space of dielectric mixture (United States)

    Tsang, L.; Newton, R. W.; Kong, J. A.


    The strong fluctuation random medium theory is applied to calculate scattering from a half-space of dielectric mixture. The first and second moments of the fields are calculated, respectively, by using the bilocal and the distorted Born approximations, and the low frequency limit is taken. The singularity of the dyadic Green's function is taken into account. Expressions for the effective permittivity for the full space case are derived. It is shown that the derived result of the effect permittivity is identical to that of the Polder and van Santern mixing formula. The correlation function of the random medium is obtained by using simple physical arguments and is expressed in terms of the fractional volumes and particle sizes of the constituents of the mixture. Backscattering coefficients of a half-space dielectric mixture are also calculated. Numerical results of the effective permittivity and backscattering coefficients are illustrated using typical parameters encountered in microwave remote sensing of dry and wet snow. It is also shown that experimental data can be matched with the theory by using physical parameters of the medium as obtained from ground truth measurements.

  1. Asymptotic Modeling of Coherent Scattering from Random Rough Layers: Application to Road Survey by GPR at Nadir

    Directory of Open Access Journals (Sweden)

    Nicolas Pinel


    Full Text Available This paper studies the coherent scattering from random rough layers made up of two uncorrelated random rough surfaces, by considering 2D problems. The results from a rigorous electromagnetic method called PILE (propagation-inside-layer expansion are used as a reference. Also, two asymptotic analytical approaches are presented and compared to the numerical model for comparison. The cases of surfaces with both Gaussian and exponential correlations are studied. This approach is applied to road survey by GPR at nadir.

  2. Compton Scattering in Plasma: Multiple Scattering Effects and Application to Laser-Plasma Acceleration

    CERN Document Server

    Kumar, Ravindra


    We explore the physics of electron acceleration in a plasma medium in an effective field theory framework. Employing a multiple Compton scattering mechanism, it is found that the acceleration can be sustained in such a medium so as to attain the energies up to the order of $O(100 \\rm{MeV})$ within a centimeter. Also, the collimation and mono-energetic electron spectrum can be obtained by proper tuning of the plasma parameters with the photon frequency. The present work is potentially useful in understanding the physics of laser-plasma accelerators.

  3. Light scattering of PMMA latex particles in benzene: structural effects

    NARCIS (Netherlands)

    Nieuwenhuis, E.A.; Vrij, A.


    Intra- and interparticle structural effects were studied in polymethylmethacrylate (PMMA) latex dispersions in a nonpolar solvent with the technique of light scattering. The required transparency of the dispersions was attained by a close matching of the refractive index of PMMA and solvent, for

  4. Resonance Elastic Scattering and Interference Effects Treatments in Subgroup Method

    Directory of Open Access Journals (Sweden)

    Yunzhao Li


    Full Text Available Based on the resonance integral (RI tables produced by the NJOY program, the conventional subgroup method usually ignores both the resonance elastic scattering and the resonance interference effects. In this paper, on one hand, to correct the resonance elastic scattering effect, RI tables are regenerated by using the Monte Carlo code, OpenMC, which employs the Doppler broadening rejection correction method for the resonance elastic scattering. On the other hand, a fast resonance interference factor method is proposed to efficiently handle the resonance interference effect. Encouraging conclusions have been indicated by the numerical results. (1 For a hot full power pressurized water reactor fuel pin-cell, an error of about +200 percent mille could be introduced by neglecting the resonance elastic scattering effect. By contrast, the approach employed in this paper can eliminate the error. (2 The fast resonance interference factor method possesses higher precision and higher efficiency than the conventional Bondarenko iteration method. Correspondingly, if the fast resonance interference factor method proposed in this paper is employed, the kinf can be improved by ∼100 percent mille with a speedup of about 4.56.

  5. Effective single scattering albedo estimation using regional climate model

    CSIR Research Space (South Africa)

    Tesfaye, M


    Full Text Available In this study, by modifying the optical parameterization of Regional Climate model (RegCM), the authors have computed and compared the Effective Single-Scattering Albedo (ESSA) which is a representative of VIS spectral region. The arid, semi-arid...

  6. Coherent electromagnetic waves in the presence of a half space of randomly distributed scatterers (United States)

    Karam, M. A.; Fung, A. K.


    The present investigation of coherent field propagation notes, upon solving the Foldy-Twersky integral equation for a half-space of small spherical scatterers illuminated by a plane wave at oblique incidence, that the coherent field for a horizontally-polarized incident wave exhibits reflectivity and transmissivity consistent with the Fresnel formula for an equivalent continuous effective medium. In the case of a vertically polarized incident wave, both the vertical and longitudinal waves obtained for the coherent field have reflectivities and transmissivities that do not agree with the Fresnel formula.

  7. A Study of the Operator Expansion Method and its Application to Scattering from Randomly Rough Dirichlet Surfaces (United States)


    34Sur la diffraction d’une onde plane par un reseau infiniment conducteur," C. R. Acad. Sci. Ser. B, 262(7), 468-471, 1966. Pierson, W. J., and L...Maradudin, "Multiple scattering of waves from random rough surfaces," Phys. Rev. B, 22(9), 4234-4240, 1980. Sommerfeld, A., Optics, Vol. IV of Lectures on

  8. Application of the extended boundary condition method to Monte Carlo simulations of scattering of waves by two-dimensional random rough surfaces (United States)

    Tsang, L.; Lou, S. H.; Chan, C. H.


    The extended boundary condition method is applied to Monte Carlo simulations of two-dimensional random rough surface scattering. The numerical results are compared with one-dimensional random rough surfaces obtained from the finite-element method. It is found that the mean scattered intensity from two-dimensional rough surfaces differs from that of one dimension for rough surfaces with large slopes.

  9. Longwave scattering effects on fluxes in broken cloud fields

    Energy Technology Data Exchange (ETDEWEB)

    Takara, E.E.; Ellingson, R.G. [Univ. of Maryland, College Park, MD (United States)


    The optical properties of clouds in the radiative energy balance are important. Most works on the effects of scattering have been in the shortwave; but longwave effects can be significant. In this work, the fluxes above and below a single cloud layer are presented, along with the errors in assuming flat black plate clouds or black clouds. The predicted fluxes are the averaged results of analysis of several fields with the same cloud amount.

  10. FDTD analysis of the light extraction efficiency of OLEDs with a random scattering layer. (United States)

    Kim, Jun-Whee; Jang, Ji-Hyang; Oh, Min-Cheol; Shin, Jin-Wook; Cho, Doo-Hee; Moon, Jae-Hyun; Lee, Jeong-Ik


    The light extraction efficiency of OLEDs with a nano-sized random scattering layer (RSL-OLEDs) was analyzed using the Finite Difference Time Domain (FDTD) method. In contrast to periodic diffraction patterns, the presence of an RSL suppresses the spectral shift with respect to the viewing angle. For FDTD simulation of RSL-OLEDs, a planar light source with a certain spatial and temporal coherence was incorporated, and the light extraction efficiency with respect to the fill factor of the RSL and the absorption coefficient of the material was investigated. The design results were compared to the experimental results of the RSL-OLEDs in order to confirm the usefulness of FDTD in predicting experimental results. According to our FDTD simulations, the light confined within the ITO-organic waveguide was quickly absorbed, and the absorption coefficients of ITO and RSL materials should be reduced in order to obtain significant improvement in the external quantum efficiency (EQE). When the extinction coefficient of ITO was 0.01, the EQE in the RSL-OLED was simulated to be enhanced by a factor of 1.8.

  11. Effective field theory and unitarity in vector boson scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sekulla, Marco [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany); Kilian, Wolfgang [Siegen Univ. (Germany); Ohl, Thorsten [Wuerzburg Univ. (Germany); Reuter, Juergen [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group


    Weak vector boson scattering at high energies will be one of the key measurements in current and upcoming LHC runs. It is most sensitive to any new physics associated with electroweak symmetry breaking. However, a conventional EFT analysis will fail at high energies. To address this problem, we present a parameter-free prescription valid for arbitrary perturbative and non-perturbative models: the T-matrix unitarization. We describe its implementation as an asymptotically consistent reference model matched to the low-energy effective theory. We show examples of typical observables of vector-boson scattering at the LHC in our unitarized framework. For many strongly-coupled models like composite Higgs models, dimension-8 operators might be actually the leading operators. In addition to those longitudinal and transversal dimension eight EFT operators, the effects of generic tensor and scalar resonances within simplified models are considered.

  12. Quark condensate effects on charmonium-pion scattering

    Indian Academy of Sciences (India)

    60, No. 5. — journal of. May 2003 physics pp. 1113–1116. Quark condensate effects on charmonium-pion scattering. F S NAVARRA and M NIELSEN. Instituto de Fısica, Universidade de S˜ao Paulo, C.P. 66318, 05389-970 S˜ao Paulo, Brazil. Abstract. The J ψπ. ¯DD£ ¯DD, ¯D£D£ and ¯D D£ cross-sections as a function of.

  13. Uncertainty analysis of standardized measurements of random-incidence absorption and scattering coefficients. (United States)

    Müller-Trapet, Markus; Vorländer, Michael


    This work presents an analysis of the effect of some uncertainties encountered when measuring absorption or scattering coefficients in the reverberation chamber according to International Organization for Standardization/American Society for Testing and Materials standards. This especially relates to the uncertainty due to spatial fluctuations of the sound field. By analyzing the mathematical definition of the respective coefficient, a relationship between the properties of the chamber and the test specimen and the uncertainty in the measured quantity is determined and analyzed. The validation of the established equations is presented through comparisons with measurement data. This study analytically explains the main sources of error and provides a method to obtain the product of the necessary minimum number of measurement positions and the band center frequency to achieve a given maximum uncertainty in the desired quantity. It is shown that this number depends on the ratio of room volume to sample surface area and the reverberation time of the empty chamber.

  14. An iterative fullwave simulation approach to multiple scattering in media with randomly distributed microbubbles (United States)

    Joshi, Aditya; Lindsey, Brooks D.; Dayton, Paul A.; Pinton, Gianmarco; Muller, Marie


    Ultrasound contrast agents (UCA), such as microbubbles, enhance the scattering properties of blood, which is otherwise hypoechoic. The multiple scattering interactions of the acoustic field with UCA are poorly understood due to the complexity of the multiple scattering theories and the nonlinear microbubble response. The majority of bubble models describe the behavior of UCA as single, isolated microbubbles suspended in infinite medium. Multiple scattering models such as the independent scattering approximation can approximate phase velocity and attenuation for low scatterer volume fractions. However, all current models and simulation approaches only describe multiple scattering and nonlinear bubble dynamics separately. Here we present an approach that combines two existing models: (1) a full-wave model that describes nonlinear propagation and scattering interactions in a heterogeneous attenuating medium and (2) a Paul-Sarkar model that describes the nonlinear interactions between an acoustic field and microbubbles. These two models were solved numerically and combined with an iterative approach. The convergence of this combined model was explored in silico for 0.5 × 106 microbubbles ml-1, 1% and 2% bubble concentration by volume. The backscattering predicted by our modeling approach was verified experimentally with water tank measurements performed with a 128-element linear array transducer. An excellent agreement in terms of the fundamental and harmonic acoustic fields is shown. Additionally, our model correctly predicts the phase velocity and attenuation measured using through transmission and predicted by the independent scattering approximation.

  15. Effects of surface and interface scattering on anomalous Hall effect in Co/Pd multilayers

    KAUST Repository

    Guo, Zaibing


    In this paper, we report the results of surface and interface scattering on anomalous Hall effect in Co/Pd multilayers with perpendicular magnetic anisotropy. The surface scattering effect has been extracted from the total anomalous Hall effect. By scaling surface scattering contribution with ρAHs∼ργss, the exponent γ has been found to decrease with the increase of surface scattering resistivity, which could account for the thickness-dependent anomalous Hall effect. Interface diffusion induced by rapid thermal annealing modifies not only the magnetization and longitudinal resistivity but also the anomalous Hall effect; a large exponent γ ∼ 5.7 has been attributed to interface scattering-dominated anomalous Hall effect.

  16. Investigation on wide-band scattering of a 2-D target above 1-D randomly rough surface by FDTD method. (United States)

    Li, Juan; Guo, Li-Xin; Jiao, Yong-Chang; Li, Ke


    Finite-difference time-domain (FDTD) algorithm with a pulse wave excitation is used to investigate the wide-band composite scattering from a two-dimensional(2-D) infinitely long target with arbitrary cross section located above a one-dimensional(1-D) randomly rough surface. The FDTD calculation is performed with a pulse wave incidence, and the 2-D representative time-domain scattered field in the far zone is obtained directly by extrapolating the currently calculated data on the output boundary. Then the 2-D wide-band scattering result is acquired by transforming the representative time-domain field to the frequency domain with a Fourier transform. Taking the composite scattering of an infinitely long cylinder above rough surface as an example, the wide-band response in the far zone by FDTD with the pulsed excitation is computed and it shows a good agreement with the numerical result by FDTD with the sinusoidal illumination. Finally, the normalized radar cross section (NRCS) from a 2-D target above 1-D rough surface versus the incident frequency, and the representative scattered fields in the far zone versus the time are analyzed in detail.

  17. Laboratory measurements of scattering matrix elements of randomly oriented Mars analog palagonite particles

    NARCIS (Netherlands)

    Muñoz, O.; Volten, H.; Hovenier, J.W.; Laan, E.; Roush, T.; Stam, D.


    We present laboratory measurements for Martian analog particles, consisting of palagonite. We measured all elements of the scattering matrix as functions of the scattering angle from 3 to 174 degrees at a wavelength of 632.8 nm. The results may be used in studies of the Martian atmosphere.

  18. Elastic scattering of surface plasmon polaritons: Modeling and experiment

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Coello, V.


    Elastic (in-plane) scattering of surface plasmon polaritons (SPP's) is modeled by considering isotropic pointlike scatterers whose responses to the incident SPP field are phenomenologically related to their effective polarizabilities. Numerical simulations of single, double, and multiple scattering...... are presented for randomly situated scatterers showing the interplay between different orders of scattering and localization phenomena. Correlation between the scattering regimes and spatial Fourier spectra of the corresponding SPP intensity distributions is considered. Various optical microcomponents (e...

  19. Resolution effects and analysis of small-angle neutron scattering data

    DEFF Research Database (Denmark)

    Pedersen, J.S.


    A discussion of the instrumental smearing effects for small-angle neutron scattering (SANS) data sets is given. It is shown that these effects can be described by a resolution function, which describes the distribution of scattering vectors probed for the nominal values of the scattering vector. ...

  20. Single realization stochastic FDTD for weak scattering waves in biological random media. (United States)

    Tan, Tengmeng; Taflove, Allen; Backman, Vadim


    This paper introduces an iterative scheme to overcome the unresolved issues presented in S-FDTD (stochastic finite-difference time-domain) for obtaining ensemble average field values recently reported by Smith and Furse in an attempt to replace the brute force multiple-realization also known as Monte-Carlo approach with a single-realization scheme. Our formulation is particularly useful for studying light interactions with biological cells and tissues having sub-wavelength scale features. Numerical results demonstrate that such a small scale variation can be effectively modeled with a random medium problem which when simulated with the proposed S-FDTD indeed produces a very accurate result.

  1. Terrestrial effects on dark matter-electron scattering experiments

    DEFF Research Database (Denmark)

    Emken, Timon; Kouvaris, Chris; Shoemaker, Ian M.


    techniques involving detection of dark matter-electron scattering offer new sensitivity to sub-GeV dark matter. Typically however it is implicitly assumed that the dark matter is not altered as it traverses the Earth to arrive at the detector. In this paper we study in detail the effects of terrestrial...... stopping on dark photon models of dark matter, and find that they significantly reduce the sensitivity of XENON10 and DAMIC. In particular we find that XENON10 only excludes masses in the range (5-3000) MeV while DAMIC only probes (20-50) MeV. Their corresponding cross section sensitivity is reduced...

  2. The leaf-shape effect on electromagnetic scattering from vegetated media (United States)

    Karam, M. A.; Fung, A. K.; Blanchard, A. J.; Shen, G. X.


    Using the generalized Rayleigh Gans approximation along with the radiative transfer method, a bistatic backscattering model for a layer of randomly oriented, elliptic-shaped leaves is formulated. Following a similar procedure the bistatic scattering model for a layer of needle-shaped leaves is also developed to simulate coniferous vegetation. The differences between the scattering characteristics of the deciduous and coniferous leaves are illustrated numerically for different orientation and incidence angles. It is found that both like and cross polarizations are needed to differentiate the difference in scattering due to the shapes of the scatterers. The calculated backscattering coefficients are compared with measured values from artificial canopies with circular-shaped leaves.

  3. Multiple and dependent scattering effects in Doppler optical coherence tomography

    NARCIS (Netherlands)

    Kalkman, J.; Bykov, A.V.; Faber, D.J.; van Leeuwen, Ton


    Doppler optical coherence tomography (OCT) is a technique to image tissue morphology and to measure flow in turbid media. In its most basic form, it is based on single (Mie) scattering. However, for highly scattering and dense media multiple and concentration dependent scattering can occur. For

  4. Molecular anisotropy effects in carbon K-edge scattering: depolarized diffuse scattering and optical anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Kevin H.


    Some polymer properties, such as conductivity, are very sensitive to short- and intermediate-range orientational and positional ordering of anisotropic molecular functional groups, and yet means to characterize orientational order in disordered systems are very limited. We demonstrate that resonant scattering at the carbon K-edge is uniquely sensitive to short-range orientation correlations in polymers through depolarized scattering at high momentum transfers, using atactic polystyrene as a well-characterized test system. Depolarized scattering is found to coexist with unpolarized fluorescence, and to exhibit pronounced anisotropy. We also quantify the spatially averaged optical anisotropy from low-angle reflectivity measurements, finding anisotropy consistent with prior visible, x-ray absorption, and theoretical studies. The average anisotropy is much smaller than that in the depolarized scattering and the two have different character. Both measurements exhibit clear spectral signatures from the phenyl rings and the polyethylene-like backbone. Discussion focuses on analysis considerations and prospects for using this depolarized scattering for studies of disorder in soft condensed matter.

  5. Effect of dust particle polarization on scattering processes in complex plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kodanova, S. K.; Ramazanov, T. S.; Bastykova, N. Kh.; Moldabekov, Zh. A. [Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, 71 Al-Farabi Str., 050040 Almaty (Kazakhstan)


    Screened interaction potentials in dusty plasmas taking into account the polarization of dust particles have been obtained. On the basis of screened potentials scattering processes for ion-dust particle and dust particle-dust particle pairs have been studied. In particular, the scattering cross section is considered. The scattering processes for which the dust grain polarization is unimportant have been found. The effect of zero angle dust particle-dust particle scattering is predicted.

  6. A study of phonon anisotropic scattering effect on silicon thermal conductivity at nanoscale

    Energy Technology Data Exchange (ETDEWEB)

    Bong, Victor N-S; Wong, Basil T. [Swinburne Sarawak Research Centre for Sustainable Technologies, Faculty of Engineering, Computing & Science, Swinburne University of Technology Sarawak Campus, 93350 Kuching, Sarawak (Malaysia)


    Previous studies have shown that anisotropy in phonon transport exist because of the difference in phonon dispersion relation due to different lattice direction, as observed by a difference in in-plane and cross-plane thermal conductivity. The directional preference (such as forward or backward scattering) in phonon propagation however, remains a relatively unexplored frontier. Our current work adopts a simple scattering probability in radiative transfer, which is called Henyey and Greenstein probability density function, and incorporates it into the phonon Monte Carlo simulation to investigate the effect of directional scattering in phonon transport. In this work, the effect of applying the anisotropy scattering is discussed, as well as its impact on the simulated thermal conductivity of silicon thin films. While the forward and backward scattering will increase and decrease thermal conductivity respectively, the extent of the effect is non-linear such that forward scattering has a more obvious effect than backward scattering.

  7. Refractive effects in the scattering of loosely bound nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Carstoiu, F.; Trache, L.; Tribble, R.E.; Gagliardi, C.A. [Texas A and M Univ., College Station, TX (United States). Cyclotron Inst; Carstoiu, F. [Laboratoire de Physique Corpusculaire, IN2P3-CNRS, ISMRA, Universite de Caen, 14 - Caen (France); Carstoiu, F. [National Institute for Physics and Nuclear Engineering, Horia Hulubei, Bucharest-Magurele (Romania)


    A study of the interaction of the loosely bound nuclei {sup 6,7}Li at 9 and 19 MeV/nucleon with light targets has been undertaken. With the determination of unambiguous optical potentials in mind, elastic data for four projectile-target combinations and one neutron transfer reaction {sup 13}C({sup 7}Li,{sup 8}Li){sup 12}C have been measured over a large angular range. The kinematical regime encompasses a region where the mean field (optical potential) has a marked variation with mass and energy, but turns out to be sufficiently surface transparent to allow strong refractive effects to be manifested in elastic scattering data at intermediate angles. The identified exotic feature, a 'plateau' in the angular distributions at intermediate angles, is fully confirmed in four reaction channels and is interpreted as a pre-rainbow oscillation resulting from the interference of the barrier and internal barrier far-side scattering sub-amplitudes. (authors)

  8. Electron scattering from neon via effective range theory

    Energy Technology Data Exchange (ETDEWEB)

    Fedus, Kamil, E-mail: [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun (Poland)


    Elastic cross-sections for electron scattering on neon from 0 energy up to 16 eV are analyzed by an analytical approach to the modified effective range theory (MERT). It is shown that energy and angular variations of elastic differential, integral and momentum transfer cross sections can be accurately parameterized by six MERT coefficients up to the energy threshold for the first Feshbach resonance. MERT parameters are determined empirically by numerical comparison with large collection of available experimental data of elastic total (integral) cross-sections. The present analysis is validated against numerous electron beams and swarm experiments. The comparison of derived MERT parameters with those found for other noble gases, helium, argon and krypton, is done. The derived scattering length (for the s-partial wave) in neon, 0.227a0, agrees well with recent theories; it is small but, differently from Ar and Kr, still positive. Analogue parameters for the p-wave and the d-wave are negative and positive respectively for all the four gases compared. (author)

  9. Higher twist effects in deeply virtual Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Pirnay, Bjoern Michael


    In this work we explore the effects of higher twist power corrections on the deeply virtual Compton scattering process. The calculation of the helicity amplitudes for all possible polarization combinations is performed within the framework of QCD operator product expansion. As a result the known accuracy of the amplitudes is improved to include the (kinematic) twist-4 contributions. For the most part the analysis focuses on spin-1/2 targets, the answers for scalar targets conveniently emerge as a byproduct. We investigate the analytical structure of these corrections and prove consistency with QCD factorization. We give an estimation of the numerical impact of the sub-leading twist contributions for proton targets with the help of a phenomenological model for the nonperturbative proton generalized parton distributions. We compare different twist approximations and relate predictions for physical observables to experiments performed by the Hall A, CLAS, HERMES, H1 and ZEUS collaborations. The estimate also includes a numerical study for planned COMPASS-II runs. Throughout the analysis special emphasis is put on the convention dependence induced by finite twist truncation of scattering amplitudes.

  10. Effective Field Theories from Soft Limits of Scattering Amplitudes. (United States)

    Cheung, Clifford; Kampf, Karol; Novotny, Jiri; Trnka, Jaroslav


    We derive scalar effective field theories-Lagrangians, symmetries, and all-from on-shell scattering amplitudes constructed purely from Lorentz invariance, factorization, a fixed power counting order in derivatives, and a fixed order at which amplitudes vanish in the soft limit. These constraints leave free parameters in the amplitude which are the coupling constants of well-known theories: Nambu-Goldstone bosons, Dirac-Born-Infeld scalars, and Galilean internal shift symmetries. Moreover, soft limits imply conditions on the Noether current which can then be inverted to derive Lagrangians for each theory. We propose a natural classification of all scalar effective field theories according to two numbers which encode the derivative power counting and soft behavior of the corresponding amplitudes. In those cases where there is no consistent amplitude, the corresponding theory does not exist.

  11. Sum of ratios of products forα-μ random variables in wireless multihop relaying and multiple scattering

    KAUST Repository

    Wang, Kezhi


    The sum of ratios of products of independent 2642 2642α-μ random variables (RVs) is approximated by using the Generalized Gamma ratio approximation (GGRA) with Gamma ratio approximation (GRA) as a special case. The proposed approximation is used to calculate the outage probability of the equal gain combining (EGC) or maximum ratio combining (MRC) receivers for wireless multihop relaying or multiple scattering systems considering interferences. Numerical results show that the newly derived approximation works very well verified by the simulation, while GRA has a slightly worse performance than GGRA when outage probability is below 0.1 but with a more simplified form.

  12. Dark matter effective field theory scattering in direct detection experiments

    Energy Technology Data Exchange (ETDEWEB)

    Schneck, K.; Cabrera, B.; Cerdeno, D. G.; Mandic, V.; Rogers, H. E.; Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Brandt, D.; Brink, P. L.; Bunker, R.; Caldwell, D. O.; Calkins, R.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, Priscilla B.; Daal, M.; Di Stefano, P. C.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Godfrey, G. L.; Golwala, S. R.; Hall, Jeter C.; Harris, H. R.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jardin, D. M.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, W.; Mahapatra, R.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Morales Mendoza, J. D.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Roberts, A.; Saab, T.; Sadoulet, B.; Sander, J.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Toback, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yang, X.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.


    We examine the consequences of the effective eld theory (EFT) of dark matter-nucleon scattering or current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral di*erences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

  13. Dark matter effective field theory scattering in direct detection experiments

    Energy Technology Data Exchange (ETDEWEB)

    Schneck, K.; Cabrera, B.; Cerdeño, D. G.; Mandic, V.; Rogers, H. E.; Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Brandt, D.; Brink, P. L.; Bunker, R.; Caldwell, D. O.; Calkins, R.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Godfrey, G. L.; Golwala, S. R.; Hall, J.; Harris, H. R.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jardin, D. M.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; Mahapatra, R.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Morales Mendoza, J. D.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Roberts, A.; Saab, T.; Sadoulet, B.; Sander, J.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Toback, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yang, X.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.


    We examine the consequences of the effective field theory (EFT) of dark matter-nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. Here. we demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. In conclusion, we discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

  14. Dark matter effective field theory scattering in direct detection experiments

    Energy Technology Data Exchange (ETDEWEB)

    Schneck, K.; Cabrera, B.; Cerdeño, D. G.; Mandic, V.; Rogers, H. E.; Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Brandt, D.; Brink, P. L.; Bunker, R.; Caldwell, D. O.; Calkins, R.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Godfrey, G. L.; Golwala, S. R.; Hall, J.; Harris, H. R.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jardin, D. M.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; Mahapatra, R.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Morales Mendoza, J. D.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Roberts, A.; Saab, T.; Sadoulet, B.; Sander, J.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Toback, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yang, X.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.


    We examine the consequences of the effective field theory (EFT) of dark matter–nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

  15. Interfacial scattering effect on anisotropic magnetoresistance and anomalous Hall effect in Ta/Fe multilayers

    KAUST Repository

    Zhang, Qiang


    The effect of interfacial scattering on anisotropic magnetoresistance (AMR) and anomalous Hall effect (AHE) was studied in the (Ta12n/Fe36n)n multilayers, where the numbers give the thickness in nanometer and n is an integer from 1 to 12. The multilayer structure has been confirmed by the XRR spectra and STEM images of cross-sections. The magneto-transport properties were measured by four-point probe method in Hall bar shaped samples in the temperature range of 5 - 300 K. The AMR increases with n, which could be ascribed to the interfacial spin-orbit scattering. At 5 K, the longitudinal resistivity (ρ) increases by 6.4 times and the anomalous Hall resistivity (ρ) increases by 49.4 times from n =1 to n =12, indicative of the interfacial scattering effect. The skew-scattering, side-jump and intrinsic contributions to the AHE were separated successfully. As n increases from 1 to 12, the intrinsic contribution decreases because of the decaying crystallinity or finite size effect and the intrinsic contribution dominated the AHE for all samples. The side jump changes from negative to positive because the interfacial scattering and intralayer scattering in Fe layers both contribute to side jump in the AHE but with opposite sign.

  16. Electron-molecule scattering in a strong laser field: Two-center interference effects (United States)

    Dakić, J.; Habibović, D.; Čerkić, A.; Busuladžić, M.; Milošević, D. B.


    Laser-assisted scattering of electrons on diatomic molecules is considered using the S -matrix theory within the second Born approximation. The first term of the expansion in powers of the scattering potential corresponds to the direct or single laser-assisted scattering of electrons on molecular targets, while the second term of this expansion corresponds to the laser-assisted rescattering or double scattering. The rescattered electrons may have considerably higher energies in the final state than those that scattered only once. For multicenter polyatomic molecules scattering and rescattering may happen at any center and in any order. All these cases contribute to the scattering amplitude and the interference of different contributions leads to an increase or a decrease of the differential cross section in particular electron energy regions. For diatomic molecules there are two such contributions for single scattering and four contributions for double scattering. Analyzing the spectra of the scattered electrons, we find two interesting effects. For certain molecular orientations, the plateaus in the electron energy spectrum, characteristic of laser-assisted electron-atom scattering, are replaced by a sequence of gradually declining maxima, caused by the two-center interference effects. The second effect is the appearance of symmetric U -shaped structures in the angle-resolved energy spectra, which are described very well by the analytical formulas we provide.

  17. A study of scattered radiation effect on digital radiography imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Cheol Ha [Dept. of Radiological Science, Dongseo University, Busan (Korea, Republic of)


    Scattered radiation is inherent phenomenon of x-ray, which occurs to the subject (or patient). Therefore it cannot be avoidable but also interacts as serious noise factor because the only meaningful information on x-ray radiography is primary x-ray photons. The purpose of this study was to quantify scattered radiation for various shooting parameters and to verify the effect of anti-scatter grid. We employed beam stopper method to characterize scatter to primary ratio. To evaluate effect on the projection images calculated contrast to noise ratio of given shooting parameters. From the experiments, we identified the scattered radiation increases in thicker patient and smaller air gap. Moreover, scattered radiation degraded contrast to noise ratio of the projection images. We find out that the anti-scatter grid rejected scattered radiation effectively, however there were not fewer than 100% of scatter to primary ratio in some shooting parameters. The results demonstrate that the scattered radiation was serious problem of medical x-ray system, we confirmed that the scattered radiation was not considerable factor of digital radiography.

  18. Effects of edge roughness on optical scattering from periodic microstructures (United States)

    Bergner, Brent C.

    Planar photonic crystals and other microstructured surfaces have important applications in a number of emerging technologies. However, these structures can be difficult to fabricate in a consistent manner. Rapid, precise measurements of critical parameters are needed to control the fabrication process, but current measurement techniques tend to be slow and often require that the sample be modified in order to make the measurement. Optical scattering can provide a rapid, non-destructive, and precise method for measuring these structures, and optical scatterometry is a good candidate technique for measuring micro-structured surfaces for process control. However, variations in the profile, such as those caused by edge roughness, can make significant contributions to the uncertainty in scatterometry measurements. Because of the multidimensional nature of the problem, modeling these variations can be computationally expensive. This dissertation examines the effects of edge roughness on optical scatterometry signals. Rigorous numerical simulations show that the effects of edge roughness are sensitive to the correlation length and the frequency content of the roughness as well as its amplitude. However, these rigorous calculations are computationally expensive. A less computationally expensive model based on a generalized Bruggeman effective medium approximation is developed and shown to be effective for modeling the effects of short correlation length edge roughness on optical scatterometry signals.

  19. Scattering of electromagnetic waves from 3D multilayer random rough surfaces based on the second-order small perturbation method: energy conservation, reflectivity, and emissivity. (United States)

    Sanamzadeh, Mohammadreza; Tsang, Leung; Johnson, Joel T; Burkholder, Robert J; Tan, Shurun


    A theoretical investigation of energy conservation, reflectivity, and emissivity in the scattering of electromagnetic waves from 3D multilayer media with random rough interfaces using the second-order small perturbation method (SPM2) is presented. The approach is based on the extinction theorem and develops integral equations for surface fields in the spectral domain. Using the SPM2, we calculate the scattered and transmitted coherent fields and incoherent fields. Reflected and transmitted powers are then found in the form of 2D integrations over wavenumber in the spectral domain. In the integrand, there is a summation over the spectral densities of each of the rough interfaces with each weighted by a corresponding kernel function. We show in this paper that there exists a "strong" condition of energy conservation in that the kernel functions multiplying the spectral density of each interface obey energy conservation exactly. This means that energy is conserved independent of the roughness spectral densities of the rough surfaces. Results of this strong condition are illustrated numerically for up to 50 rough interfaces without requiring specification of surface roughness properties. Two examples are illustrated. One is a multilayer configuration having weak contrasts between adjacent layers, random layer thicknesses, and randomly generated permittivity profiles. The second example is a photonic crystal of periodically alternating permittivities of larger dielectric contrast. The methodology is applied to study the effect of roughness on the brightness temperatures of the Antarctic ice sheet, which is characterized by layers of ice with permittivity fluctuations in addition to random rough interfaces. The results show that the influence of roughness can significantly increase horizontally polarized thermal emission while leaving vertically polarized emissions relatively unaffected.

  20. Classical theory of atom-surface scattering: The rainbow effect (United States)

    Miret-Artés, Salvador; Pollak, Eli


    The scattering of heavy atoms and molecules from surfaces is oftentimes dominated by classical mechanics. A large body of experiments have gathered data on the angular distributions of the scattered species, their energy loss distribution, sticking probability, dependence on surface temperature and more. For many years these phenomena have been considered theoretically in the framework of the “washboard model” in which the interaction of the incident particle with the surface is described in terms of hard wall potentials. Although this class of models has helped in elucidating some of the features it left open many questions such as: true potentials are clearly not hard wall potentials, it does not provide a realistic framework for phonon scattering, and it cannot explain the incident angle and incident energy dependence of rainbow scattering, nor can it provide a consistent theory for sticking. In recent years we have been developing a classical perturbation theory approach which has provided new insight into the dynamics of atom-surface scattering. The theory includes both surface corrugation as well as interaction with surface phonons in terms of harmonic baths which are linearly coupled to the system coordinates. This model has been successful in elucidating many new features of rainbow scattering in terms of frictions and bath fluctuations or noise. It has also given new insight into the origins of asymmetry in atomic scattering from surfaces. New phenomena deduced from the theory include friction induced rainbows, energy loss rainbows, a theory of super-rainbows, and more. In this review we present the classical theory of atom-surface scattering as well as extensions and implications for semiclassical scattering and the further development of a quantum theory of surface scattering. Special emphasis is given to the inversion of scattering data into information on the particle-surface interactions.

  1. Formal analogy between Compton scattering and Doppler effect

    DEFF Research Database (Denmark)

    Nielsen, A.; Olsen, Jørgen Seir


    Viewed from the scatterer, the energy of the incoming photon or particle is equal to that of the outgoing, and the angle of incidence is equal to the angle of reflection, when the direction of the velocity of the scatterer after the collision is taken as reference. This paper sets out to prove th...

  2. Transverse spin effects in polarized semi inclusive deep inelastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Pappalardo, Luciano Libero


    The theoretical framework for the inclusive and semi-inclusive deep inelastic scattering is provided in Chapters 2 and 3, respectively. While a phenomenological and historical perspective is adopted in Chapter 2 for the description of the inclusive processes, a detailed treatment of the formalism concerning the physics of the transverse degrees of freedom of the nucleon is presented in Chapter 3. In Chapter 4 the main components of the HERMES experimental apparatus are presented. The extraction of the Collins and Sivers moments is discussed in Chapter 5 after a brief overview of the main steps of the data analysis. A selection of systematic studies is also reported at the end of the chapter. Chapter 6 is completely devoted to the estimate of the acceptance and smearing effects on the extracted azimuthal moments. A crucial role in the studies presented is played by a newly developed Monte Carlo generator which simulates azimuthal asymmetries arising from intrinsic quark momenta. A novel approach for the estimate of the acceptance effects is presented at the end of the chapter. The extracted Collins and Sivers moments, corrected for the acceptance effects, are shown in Chapter 7. The discussion and the interpretation of the results, together with a preliminary extraction of the Sivers polarization, are also treated in Chapter 7. Final conclusions and a brief summary are reported in Chapter 8. (orig.)

  3. Focusing effects in laser-electron Thomson scattering

    Directory of Open Access Journals (Sweden)

    Chris Harvey


    Full Text Available We study the effects of laser pulse focusing on the spectral properties of Thomson scattered radiation. Modeling the laser as a paraxial beam we find that, in all but the most extreme cases of focusing, the temporal envelope has a much bigger effect on the spectrum than the focusing itself. For the case of ultrashort pulses, where the paraxial model is no longer valid, we adopt a subcycle vector beam description of the field. It is found that the emission harmonics are blue shifted and broaden out in frequency space as the pulse becomes shorter. Additionally the carrier envelope phase becomes important, resulting in an angular asymmetry in the spectrum. We then use the same model to study the effects of focusing beyond the limit where the paraxial expansion is valid. It is found that fields focussed to subwavelength spot sizes produce spectra that are qualitatively similar to those from subcycle pulses due to the shortening of the pulse with focusing. Finally, we study high-intensity fields and find that, in general, the focusing makes negligible difference to the spectra in the regime of radiation reaction.

  4. Focussing effects in laser-electron Thomson scattering

    CERN Document Server

    Harvey, C; Holkundkar, A R


    We study the effects of laser pulse focussing on the spectral properties of Thomson scattered radiation. Modelling the laser as a paraxial beam we find that, in all but the most extreme cases of focussing, the temporal envelope has a much bigger effect on the spectrum than the focussing itself. For the case of ultra-short pulses where the paraxial model is no longer valid, we adopt a sub-cycle vector beam description of the field. It is found that the emission harmonics are blue shifted and broaden out in frequency space as the pulse becomes shorter. Additionally the carrier envelope phase becomes important, resulting in an angular asymmetry in the spectrum. We then use the same model to study the effects of focussing beyond the limit where the paraxial expansion is valid. It is found that fields focussed to sub-wavelength spot sizes produce spectra that are qualitatively similar to those from sub-cycle pulses due to the shortening of the pulse with focussing. Finally, we study high-intensity fields and find ...

  5. Time and direction of arrival detection and filtering for imaging in strongly scattering random media

    CERN Document Server

    Borcea, Liliana; Tsogka, Chrysoula


    We study detection and imaging of small reflectors in heavy clutter, using an array of transducers that emits and receives sound waves. Heavy clutter means that multiple scattering of the waves in the heterogeneous host medium is strong and overwhelms the arrivals from the small reflectors. Building on the adaptive time-frequency filter of [1], we propose a robust method for detecting the direction of arrival of the direct echoes from the small reflectors, and suppressing the unwanted clutter backscatter. This improves the resolution of imaging. We illustrate the performance of the method with realistic numerical simulations in a non-destructive testing setup.

  6. Perturbation Theory for Scattering from Multilayers with Randomly Rough Fractal Interfaces: Remote Sensing Applications. (United States)

    Imperatore, Pasquale; Iodice, Antonio; Riccio, Daniele


    A general, approximate perturbation method, able to provide closed-form expressions of scattering from a layered structure with an arbitrary number of rough interfaces, has been recently developed. Such a method provides a unique tool for the characterization of radar response patterns of natural rough multilayers. In order to show that, here, for the first time in a journal paper, we describe the application of the developed perturbation theory to fractal interfaces; we then employ the perturbative method solution to analyze the scattering from real-world layered structures of practical interest in remote sensing applications. We focus on the dependence of normalized radar cross section on geometrical and physical properties of the considered scenarios, and we choose two classes of natural stratifications: wet paleosoil covered by a low-loss dry sand layer and a sea-ice layer above water with dry snow cover. Results are in accordance with the experimental evidence available in the literature for the low-loss dry sand layer, and they may provide useful indications about the actual ability of remote sensing instruments to perform sub-surface sensing for different sensor and scene parameters.

  7. Perturbation Theory for Scattering from Multilayers with Randomly Rough Fractal Interfaces: Remote Sensing Applications

    Directory of Open Access Journals (Sweden)

    Pasquale Imperatore


    Full Text Available A general, approximate perturbation method, able to provide closed-form expressions of scattering from a layered structure with an arbitrary number of rough interfaces, has been recently developed. Such a method provides a unique tool for the characterization of radar response patterns of natural rough multilayers. In order to show that, here, for the first time in a journal paper, we describe the application of the developed perturbation theory to fractal interfaces; we then employ the perturbative method solution to analyze the scattering from real-world layered structures of practical interest in remote sensing applications. We focus on the dependence of normalized radar cross section on geometrical and physical properties of the considered scenarios, and we choose two classes of natural stratifications: wet paleosoil covered by a low-loss dry sand layer and a sea-ice layer above water with dry snow cover. Results are in accordance with the experimental evidence available in the literature for the low-loss dry sand layer, and they may provide useful indications about the actual ability of remote sensing instruments to perform sub-surface sensing for different sensor and scene parameters.

  8. Effect of scatter on image quality in synchrotron radiation mammography (United States)

    Moeckli, Raphael; Verdun, Francis R.; Fiedler, Stefan; Pachoud, Marc; Schnyder, Pierre; Valley, Jean-Francois


    The display of low-contrast structures and fine microcalcifications is essential for the early diagnosis of breast cancer. In order to achieve a high image quality level with a minimum amount of radiation delivered to the patient, the use of different spectra (Mo or Rh anode and filters) was introduced. The European Synchrotron Radiation Facility is able to produce a monochromatic beam with a high photon flux. It is thus a powerful tool to study the effect of beam energy on image quality and dose in mammography. Our image quality assessment is based on the calculation of the size of the smallest microcalcification detectable on a radiograph, derived from the statistical decision theory. The mean glandular dose is simultaneously measured. Compared with conventional mammography units, the monochromaticity of synchrotron beams improves contrast and the use of a slit instead of an anti-scatter grid leads to a higher primary beam transmission. The relative contribution of these two effects on image quality and dose is discussed.

  9. Optical memory effect from polarized Laguerre-Gaussian light beam in light-scattering turbid media (United States)

    Shumyatsky, Pavel; Milione, Giovanni; Alfano, Robert R.


    Propagation effects of polarized Laguerre-Gaussian light with different orbital angular momentum (L) in turbid media are described. The optical memory effect in scattering media consisting of small and large size (compared to the wavelength) scatterers is investigated for scattered polarized light. Imaging using polarized laser modes with a varying orbital strength L-parameter was performed. The backscattered image quality (contrast) was enhanced by more than an order of magnitude using circularly polarized light when the concentration of scatterers was close to invisibility of the object.

  10. Scattering Effects of Solar Panels on Space Station Antenna Performance (United States)

    Panneton, Robert J.; Ngo, John C.; Hwu, Shian U.; Johnson, Larry A.; Elmore, James D.; Lu, Ba P.; Kelley, James S.


    Characterizing the scattering properties of the solar array panels is important in predicting Space Station antenna performance. A series of far-field, near-field, and radar cross section (RCS) scattering measurements were performed at S-Band and Ku-Band microwave frequencies on Space Station solar array panels. Based on investigation of the measured scattering patterns, the solar array panels exhibit similar scattering properties to that of the same size aluminum or copper panel mockup. As a first order approximation, and for worse case interference simulation, the solar array panels may be modeled using perfect reflecting plates. Numerical results obtained using the Geometrical Theory of Diffraction (GTD) modeling technique are presented for Space Station antenna pattern degradation due to solar panel interference. The computational and experimental techniques presented in this paper are applicable for antennas mounted on other platforms such as ship, aircraft, satellite, and space or land vehicle.

  11. Effects of Multiple Photon Scattering in Deciduous Tree Canopies (United States)


    goniometric apparatus shown in Figure 2 and depicted schematically in Figure 3. A linearly polarized 1064 nanometer pulsed laser (>6μJ pulse energy) is...T. W. Brakke, “ Goniometric measurements of light scattered in the principle plane from leaves,” Geoscience and Remote Sensing Symposium 2, 508-510... Goniometric measurements of light scattered in the principle plane from leaves,” IEEE Geoscience and Remote Sensing, 508-510 (1992) 36 J. L. Privette, R. B

  12. A Comparison of Nuclear Effects in High-Energy Leptonic and Hadronic Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Rees, Claude David [Univ. of Washington, Seattle, WA (United States)


    A neutrino-Neon scattering experiment using the Fermilab 15 foot bubble chamber for analysis is compared with a pi plus-(pi minus)-Neon scattering experiment at 30 and 64 GeV/c in the CERN BEBC bubbble chamber. The comparison analyzes nuclear effects excluding the EMC effect.

  13. Support scattering effects on low-gain satellite antenna pattern measurements

    DEFF Research Database (Denmark)

    Appel-Hansen, Jørgen


    The purpose of the present investigation is to determine the difference between the scattering effects from two types of supports on satellite antenna pattern measurements. The difference in scattering effects is estimated by comparing low-gain antenna patterns recorded when using a foam tower...

  14. Global effects of moon phase on nocturnal acoustic scattering layers

    KAUST Repository

    Prihartato, PK


    © Inter-Research 2016. The impact of moon phase on the global nocturnal vertical distribution of acoustic scattering layers (SLs) in the upper 200 m was studied during the Malaspina expedition that circumnavigated the world. We assessed the nocturnal weighted mean depths and the vertical extension of the SL (the range between the upper 25th percentile and lower 75th percentile of the backscatter) and used a generalized additive model to reveal the relationship between the nocturnal vertical distribution of the SL and moon phase, as well as other environmental factors. Moon phase significantly affected the SL distribution on a global scale, in contrast to other factors such as dissolved oxygen, temperature and fluorescence, which each correlated with nocturnal SL distribution during the large geographic coverage. Full moon caused a deepening effect on the nocturnal SL. Contrary to expectations, the shallowest distribution was not observed during the darkest nights (new moon) and there was no difference in vertical distribution between new moon and intermediate moon phases. We conclude that the trend of deepening SL during approximately full moon (bright nights) is a global phenomenon related to anti-predator behavior.

  15. Effects of elastic and inelastic scattering in giving electrons tortuous paths in matter. (United States)

    Turner, J E; Hamm, R N


    Heavy charged particles travel in essentially straight lines in matter, while electrons travel in tortuous paths. Frequent multiple elastic Coulomb scattering by atomic nuclei is often cited as the reason for this electron behavior. Heavy charged particles also undergo multiple Coulomb scattering. However, because they are massive, significant deflections occur only in rare, close encounters with nuclei. In contrast to heavy particles, the inelastic interaction of an electron with an atomic electron represents a collision with a particle of equal mass. In principle, therefore, repeated inelastic scattering of an electron can also produce large-angle deflections and thus contribute to the tortuous nature of an electron's track. To investigate the relative importance of elastic and inelastic scattering on determining the appearance of electron tracks, detailed Monte Carlo transport computations have been carried out for monoenergetic pencil beams of electrons normally incident on a water slab with initial energies from 1 keV to 1 MeV. The calculations have been performed with deflections due to (1) inelastic scattering only, (2) elastic scattering only, and (3) both types of scattering. Results are presented to show the spreading of the pencil beams with depth in the slab, the transmission through slabs of different thicknesses, and back-scattering from the slab. The results show that elastic nuclear scattering is indeed the principal physical process that causes electron paths to be tortuous; however, the smaller effect of inelastic electronic scattering is far from negligible.

  16. Statistics of α-μ Random Variables and Their Applications inWireless Multihop Relaying and Multiple Scattering Channels

    KAUST Repository

    Wang, Kezhi


    Exact results for the probability density function (PDF) and cumulative distribution function (CDF) of the sum of ratios of products (SRP) and the sum of products (SP) of independent α-μ random variables (RVs) are derived. They are in the form of 1-D integral based on the existing works on the products and ratios of α-μ RVs. In the derivation, generalized Gamma (GG) ratio approximation (GGRA) is proposed to approximate SRP. Gamma ratio approximation (GRA) is proposed to approximate SRP and the ratio of sums of products (RSP). GG approximation (GGA) and Gamma approximation (GA) are used to approximate SP. The proposed results of the SRP can be used to calculate the outage probability (OP) for wireless multihop relaying systems or multiple scattering channels with interference. The proposed results of the SP can be used to calculate the OP for these systems without interference. In addition, the proposed approximate result of the RSP can be used to calculate the OP of the signal-To-interference ratio (SIR) in a multiple scattering system with interference. © 1967-2012 IEEE.

  17. Diffuse scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kostorz, G. [Eidgenoessische Technische Hochschule, Angewandte Physik, Zurich (Switzerland)


    While Bragg scattering is characteristic for the average structure of crystals, static local deviations from the average lattice lead to diffuse elastic scattering around and between Bragg peaks. This scattering thus contains information on the occupation of lattice sites by different atomic species and on static local displacements, even in a macroscopically homogeneous crystalline sample. The various diffuse scattering effects, including those around the incident beam (small-angle scattering), are introduced and illustrated by typical results obtained for some Ni alloys. (author) 7 figs., 41 refs.

  18. Cramér-Rao Bound Study of Multiple Scattering Effects in Target Separation Estimation

    Directory of Open Access Journals (Sweden)

    Edwin A. Marengo


    Full Text Available The information about the distance of separation between two-point targets that is contained in scattering data is explored in the context of the scalar Helmholtz operator via the Fisher information and associated Cramér-Rao bound (CRB relevant to unbiased target separation estimation. The CRB results are obtained for the exact multiple scattering model and, for reference, also for the single scattering or Born approximation model applicable to weak scatterers. The effects of the sensing configuration and the scattering parameters in target separation estimation are analyzed. Conditions under which the targets' separation cannot be estimated are discussed for both models. Conditions for multiple scattering to be useful or detrimental to target separation estimation are discussed and illustrated.

  19. Effect of scattering albedo on attenuation and polarization of light underwater. (United States)

    Cochenour, Brandon; Mullen, Linda; Muth, John


    Recent work on underwater laser communication links uses polarization discrimination to improve system performance [Appl. Opt.48, 328 (2009)] [in Proceedings of IEEE Oceans 2009 (IEEE, 2009), pp. 1-4]. In the laboratory, Maalox antacid is commonly used as a scattering agent. While its scattering function closely mimics that of natural seawaters, its scattering albedo can be much higher, as Maalox particles tend to be less absorbing. We present a series of experiments where Nigrosin dye is added to Maalox in order to more accurately recreate real-world absorption and scattering properties. We consider the effect that scattering albedo has on received power and the degree of depolarization of forward-scattered light in the context of underwater laser communication links.

  20. Simulation study of the backward-scattering effect in Compton imager. (United States)

    Xiaofeng, Guo; Qingpei, Xiang; Dongfeng, Tian; Yi, Wang; Fanhua, Hao; Yingzeng, Zhang; Chengsheng, Chu; Na, Liang


    In the field of nuclear medicine, nuclear security and astrophysics, Compton imaging is a promising technique for gamma-ray source imaging. We are developing a Compton imager using two layers of CdZnTe pixel array detectors. In this paper, the backward-scattering effect within such imagers is numerically studied using Geant4 Monte Carlo Package. From images reconstructed based on forward-scattering and backward-scattering imaging events, the imaging precision was investigated in a comparative analysis, in regard to energy resolution and position resolution. Furthermore, to establish a method to use backward-scattering imaging events properly so that the imaging efficiency can be significantly improved, the difference between reconstruction from forward-scattering and backward-scattering imaging events was analyzed to uncover a causal mechanism. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. On scattering effects for volume sources in low-energy photon spectrometry. (United States)

    Lépy, Marie-Christine; Brondeau, Laurine; Ferreux, Laurent; Pierre, Sylvie


    In this study, different aspects of the Compton scattering inside volume sources are illustrated using experimental approach and Monte Carlo simulation. For the low-energy range (below 100 keV) scattered events represents around 30% of the whole spectrum. Influence of the source-detector geometry is discussed. The scattering effects induce strong differences in spectrum shape for different geometrical conditions. This should influence efficiency transfer factors. A new approach is proposed, including the scattered events, to avoid complex peak area determination. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Numerical analysis of space-weathering effects on light scattering by asteroid surfaces (United States)

    Markkanen, J.; Martikainen, J.; Penttilä, A.; Muinonen, K.


    We have developed a novel radiative transfer (RT) / geometric optics (GO) numerical approach which allows us to model space-weathering effects on light scattering by planetary surfaces. Our analysis show that the space weathering has a major impact on light-scattering features of asteroids at the visible wavelengths.

  3. Experimental determination of the effective refractive index in strongly scattering media

    NARCIS (Netherlands)

    Gómez Rivas, J.; Gomez Rivas, J.; Hau, D.H.; Imhof, A.; Sprik, R.; Bret, B.P.J.; Johnson, P.M.; Hijmans, T.W.; Lagendijk, Aart


    Measurements of the angular-resolved-optical transmission through strongly scattering samples of porous gallium phosphide are described. Currently porous GaP is the strongest-scattering material for visible light. From these measurements the effective refractive index and the average reflectivity at

  4. Interpreting parameters in the logistic regression model with random effects

    DEFF Research Database (Denmark)

    Larsen, Klaus; Petersen, Jørgen Holm; Budtz-Jørgensen, Esben


    interpretation, interval odds ratio, logistic regression, median odds ratio, normally distributed random effects......interpretation, interval odds ratio, logistic regression, median odds ratio, normally distributed random effects...

  5. Field Induced Memory Effects in Random Nematics

    Directory of Open Access Journals (Sweden)

    Amid Ranjkesh


    Full Text Available We studied numerically external field induced memory effects in randomly perturbed nematic liquid crystals. Random anisotropy nematic-type lattice model was used. The impurities imposing orientational disorder were randomly spatially distributed with the concentration p below the percolation threshold. Simulations were carried for finite temperatures, where we varied p, interaction strength between LC molecules, and impurities and external field B. In the {B,T} plane we determined lines separating short range—quasi long range and quasi long range—long range order. Furthermore, crossover regime separating external field and random field dominated regime was estimated. We calculated remanent nematic ordering in samples at B=0 as a function of the previously experienced external field strength B.

  6. The gated integration technique for the accurate measurement of the autocorrelation function of speckle intensities scattered from random phase screens (United States)

    Zhang, Ningyu; Cheng, Chuanfu; Teng, Shuyun; Chen, Xiaoyi; Xu, Zhizhan


    A new approach based on the gated integration technique is proposed for the accurate measurement of the autocorrelation function of speckle intensities scattered from a random phase screen. The Boxcar used for this technique in the acquisition of the speckle intensity data integrates the photoelectric signal during its sampling gate open, and it repeats the sampling by a preset number, m. The average analog of the m samplings output by the Boxcar enhances the signal-to-noise ratio by √{m}, because the repeated sampling and the average make the useful speckle signals stable, while the randomly varied photoelectric noise is suppressed by 1/√{m}. In the experiment, we use an analog-to-digital converter module to synchronize all the actions such as the stepped movement of the phase screen, the repeated sampling, the readout of the averaged output of the Boxcar, etc. The experimental results show that speckle signals are better recovered from contaminated signals, and the autocorrelation function with the secondary maximum is obtained, indicating that the accuracy of the measurement of the autocorrelation function is greatly improved by the gated integration technique.

  7. Effective Lagrangians and chiral random matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Halasz, M.A.; Verbaarschot, J.J.M. [Department of Physics, State University of New York, Stony Brook, New York 11794 (United States)


    Recently, sum rules were derived for the inverse eigenvalues of the Dirac operator. They were obtained in two different ways: (i) starting from the low-energy effective Lagrangian and (ii) starting from a random matrix theory with the symmetries of the Dirac operator. This suggests that the effective theory can be obtained directly from the random matrix theory. Previously, this was shown for three or more colors with fundamental fermions. In this paper we construct the effective theory from a random matrix theory for two colors in the fundamental representation and for an arbitrary number of colors in the adjoint representation. We construct a fermionic partition function for Majorana fermions in Euclidean spacetime. Their reality condition is formulated in terms of complex conjugation of the second kind.

  8. Small-angle neutron scattering studies of nonionic surfactant: Effect ...

    Indian Academy of Sciences (India)

    concentration of sugar. The structure of micelles is almost independent of the different types of sugars used. Keywords. Small-angle neutron scattering; nonionic surfactant; micellar aggregation number. PACS Nos 61.12.Ex; 82.70.Uv. 1. Introduction. Surfactant molecules self assemble into aggregates in aqueous solution to ...

  9. Ultrasound effects and neutron scattering in UPt3

    DEFF Research Database (Denmark)

    Bruls, G.; Weber, D.; Kouroudis, I.


    We present results of sound propagation measurements and neutron scattering experiments on one and the same sample of the heavy fermion substance UPt3. From these experiments we deduce a B-T phase diagram of the small-moment spin density wave region in this compound for magnetic field B parallel-...

  10. Characterization of the angular memory effect of scattered light in biological tissues. (United States)

    Schott, Sam; Bertolotti, Jacopo; Léger, Jean-Francois; Bourdieu, Laurent; Gigan, Sylvain


    High resolution optical microscopy is essential in neuroscience but suffers from scattering in biological tissues and therefore grants access to superficial brain layers only. Recently developed techniques use scattered photons for imaging by exploiting angular correlations in transmitted light and could potentially increase imaging depths. But those correlations ('angular memory effect') are of a very short range and should theoretically be only present behind and not inside scattering media. From measurements on neural tissues and complementary simulations, we find that strong forward scattering in biological tissues can enhance the memory effect range and thus the possible field-of-view by more than an order of magnitude compared to isotropic scattering for ∼1 mm thick tissue layers.

  11. Random effect selection in generalised linear models

    DEFF Research Database (Denmark)

    Denwood, Matt; Houe, Hans; Forkman, Björn

    We analysed abattoir recordings of meat inspection codes with possible relevance to onfarm animal welfare in cattle. Random effects logistic regression models were used to describe individual-level data obtained from 461,406 cattle slaughtered in Denmark. Our results demonstrate that the largest ...


    DEFF Research Database (Denmark)

    Tonboe, Rasmus; Andersen, Søren; Pedersen, Leif Toudal


    A radiative transfer model is used to simulate the sea ice radar altimeter effective scattering surface variability as a function of snow depth and density. Under dry snow conditions without layering these are the primary snow parameters affecting the scattering surface variability. The model...... is initialised with in situ data collected during the May 2004 GreenIce ice camp in the Lincoln Sea (73ºW; 85ºN). Our results show that the snow cover is important for the effective scattering surface depth in sea ice and thus for the range measurement, ice freeboard and ice thickness estimation....

  13. Asymmetrically pumped Bragg scattering with the effects of nonlinear phase modulation

    DEFF Research Database (Denmark)

    Andersen, Lasse Mejling; Friis, Søren Michael Mørk; Reddy, Dileep V.


    We derive exact solutions to asymmetrically pumped Bragg scattering with nonlinear phase-modulation (NPM) and show that this setup allows for the frequency conversion of many temporal modes, while reducing the effects due to NPM....

  14. Strong coupling effects in near-barrier heavy-ion elastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Keeley, N. [National Centre for Nuclear Research, Otwock (Poland); Kemper, K.W. [The Florida State University, Department of Physics, Tallahassee, Florida (United States); University of Warsaw, Heavy Ion Laboratory, Warsaw (Poland); Rusek, K. [University of Warsaw, Heavy Ion Laboratory, Warsaw (Poland)


    Accurate elastic scattering angular distribution data measured at bombarding energies just above the Coulomb barrier have shapes that can markedly differ from or be the same as the expected classical Fresnel scattering pattern depending on the structure of the projectile, the target or both. Examples are given such as {sup 18}O + {sup 184}W and {sup 16}O + {sup 148,} {sup 152}Sm, where the expected rise above Rutherford scattering due to Coulomb-nuclear interference is damped by coupling to the target excited states, and the extreme case of {sup 11}Li scattering, where coupling to the {sup 9}Li + n + n continuum leads to an elastic scattering shape that cannot be reproduced by any standard optical model parameter set. An early indication that the projectile structure can modify the elastic scattering angular distribution was the large vector analyzing powers observed in polarised {sup 6}Li scattering. The recent availability of high-quality {sup 6}He, {sup 11}Li and {sup 11}Be data provides further examples of the influence that coupling effects can have on elastic scattering. Conditions for strong projectile-target coupling effects are presented with special emphasis on the importance of the beam-target charge combination being large enough to bring about the strong coupling effects. Several measurements are proposed that can lead to further understanding of strong coupling effects by both inelastic excitation and nucleon transfer on near-barrier elastic scattering. A final note on the anomalous nature of {sup 8}B elastic scattering is presented as it possesses a more or less normal Fresnel scattering shape whereas one would a priori not expect this due to the very low breakup threshold of {sup 8}B. The special nature of {sup 11}Li is presented as it is predicted that no matter how far above the Coulomb barrier the elastic scattering is measured, its shape will not appear as Fresnel like whereas the elastic scattering of all other loosely bound nuclei studied to

  15. Application of the Finite Element Method to Random Rough Surface Scattering with Neumann Boundary Conditions (United States)


    by the method of moments [1,3, 5,16,17). A plane wave is tapered to avoid edge effects from a finite surface using a Gaussian taper function which...Finite Element Methods in CAD: Electrical and Magnectic Fields, Springer-Verlag New York Inc., New York, 1987. [13] Shen, J. and A.A. Maradudin

  16. New effects in low energy scattering of p{mu} atoms

    Energy Technology Data Exchange (ETDEWEB)

    Wozniak, J. [Institute of Physics and Nuclear Techniques (Poland); Adamczak, A. [Institute of Nuclear Physics (Poland); Beer, G.A. [University of Victoria (Canada); Bystritsky, V.M. [Joint Institute for Nuclear Research (Russian Federation); Filipowicz, M. [Institute of Physics and Nuclear Techniques (Poland); Fujiwara, M.C. [University of British Columbia (Canada); Huber, T.M. [Gustavus Adolphus College (United States); Jacot-Guillarmod, R. [University of Fribourg (Switzerland); Kammel, P. [University of California (United States); Kim, S.K. [Jeonbuk National University (Korea, Republic of); Knowles, P.E. [University of Fribourg (Switzerland); Kunselman, A.R. [University of Wyoming (United States); Maier, M. [University of Victoria (Canada); Markushin, V.E. [Paul Scherrer Institute (Switzerland); Marshall, G.M. [TRIUMF (Canada); Mulhauser, F. [University of Fribourg (Switzerland); Olin, A. [University of Victoria (Canada); Petitjean, C. [Paul Scherrer Institute (Switzerland); Porcelli, T.A. [University of Victoria (Canada); Stolupin, V.A. [Joint Institute for Nuclear Research (Russian Federation)] (and others)


    Strong solid state effects in low energy scattering of p{mu} atoms in solid hydrogen are reported and analyzed. Such effects have been observed in TRIUMF experiment E742 where muons are stopped in thin frozen (3 K) layers of hydrogen. Emission of low energy p{mu} atoms from the hydrogen layer into adjacent vacuum was much higher than expected, based on calculations which ignored the solid nature of hydrogen. Monte Carlo simulations, performed using the scattering cross-sections with solid state effects taken into account, show the important role of the coherent elastic Bragg scattering in the diffusion of p{mu} atoms. For p{mu} energies lower than the Bragg cut-off limit ({approx}2 meV) the total scattering cross-section falls by several orders of magnitude, the hydrogen target becomes transparent and the emission of cold p{mu} atoms takes place.

  17. Room scatter effects in Total Skin Electron Irradiation: Monte Carlo simulation study. (United States)

    Nevelsky, Alexander; Borzov, Egor; Daniel, Shahar; Bar-Deroma, Raquel


    Total Skin Electron Irradiation (TSEI) is a complex technique which usually involves the use of large electron fields and the dual-field approach. In this situation, many electrons scattered from the treatment room floor are produced. However, no investigations of the effect of scattered electrons in TSEI treatments have been reported. The purpose of this work was to study the contribution of floor scattered electrons to skin dose during TSEI treatment using Monte Carlo (MC) simulations. All MC simulations were performed with the EGSnrc code. Influence of beam energy, dual-field angle, and floor material on the contribution of floor scatter was investigated. Spectrum of the scattered electrons was calculated. Measurements of dose profile were performed in order to verify MC calculations. Floor scatter dependency on the floor material was observed (at 20 cm from the floor, scatter contribution was about 21%, 18%, 15%, and 12% for iron, concrete, PVC, and water, respectively). Although total dose profiles exhibited slight variation as functions of beam energy and dual-field angle, no dependence of the floor scatter contribution on the beam energy or dual-field angle was found. The spectrum of the scattered electrons was almost uniform between a few hundred KeV to 4 MeV, and then decreased linearly to 6 MeV. For the TSEI technique, dose contribution due to the electrons scattered from the room floor may be clinically significant and should be taken into account during design and commissioning phases. MC calculations can be used for this task. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  18. Satellite peaks in the scattering of light from the two-dimensional randomly rough surface of a dielectric film on a planar metal surface. (United States)

    Nordam, T; Letnes, P A; Simonsen, I; Maradudin, A A


    A nonperturbative, purely numerical, solution of the reduced Rayleigh equation for the scattering of p- and s-polarized light from a dielectric film with a two-dimensional randomly rough surface deposited on a planar metallic substrate, has been carried out. It is found that satellite peaks are present in the angular dependence of the elements of the mean differential reflection coefficient in addition to an enhanced backscattering peak. This result resolves a conflict between the results of earlier approximate theoretical studies of scattering from this system.

  19. Scattering effect of submarine hull on propeller non-cavitation noise (United States)

    Wei, Yingsan; Shen, Yang; Jin, Shuanbao; Hu, Pengfei; Lan, Rensheng; Zhuang, Shuangjiang; Liu, Dezhi


    This paper investigates the non-cavitation noise caused by propeller running in the wake of submarine with the consideration of scattering effect caused by submarine's hull. The computation fluid dynamics (CFD) and acoustic analogy method are adopted to predict fluctuating pressure of propeller's blade and its underwater noise radiation in time domain, respectively. An effective iteration method which is derived in the time domain from the Helmholtz integral equation is used to solve multi-frequency waves scattering due to obstacles. Moreover, to minimize time interpolation caused numerical errors, the pressure and its derivative at the sound emission time is obtained by summation of Fourier series. It is noted that the time averaging algorithm is used to achieve a convergent result if the solution oscillated in the iteration process. Meanwhile, the developed iteration method is verified and applied to predict propeller noise scattered from submarine's hull. In accordance with analysis results, it is summarized that (1) the scattering effect of hull on pressure distribution pattern especially at the frequency higher than blade passing frequency (BPF) is proved according to the contour maps of sound pressure distribution of submarine's hull and typical detecting planes. (2) The scattering effect of the hull on the total pressure is observable in noise frequency spectrum of field points, where the maximum increment is up to 3 dB at BPF, 12.5 dB at 2BPF and 20.2 dB at 3BPF. (3) The pressure scattered from hull is negligible in near-field of propeller, since the scattering effect surrounding analyzed location of propeller on submarine's stern is significantly different from the surface ship. This work shows the importance of submarine's scattering effect in evaluating the propeller non-cavitation noise.

  20. Manifestations of Nonlocal Exchange, Correlation, and Dynamic Effects in X-Ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Jung, M.; Dunford, R.W.; Gemmell, D.S.; Kanter, E.P.; Kraessig, B.; LeBrun, T.W.; Southworth, S.H.; Young, L. [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Carney, J.P.; LaJohn, L.; Pratt, R.H. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Bergstrom, P.M. Jr. [N Division, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)


    We report precise measurements of differential x-ray scattering cross sections in Ne and He from 11{endash}22thinspthinspkeV and develop a method for obtaining predictions of comparable accuracy (1{percent} ). The measurement of ratios (total scattering in Ne to He and Compton to Rayleigh scattering in Ne) facilitates comparison to theories. We find evidence for the need to include nonlocal exchange, electron correlation, and dynamic effects for an accurate description at low Z and conclude that no single current theory is sufficient. {copyright} {ital 1998} {ital The American Physical Society }

  1. The effects of scattering and mirror reflectivity on the performance of a ruby laser. (United States)

    Edwards, J G


    The output energy expected from a conventional ruby laser generator with plane parallel mirrors is calculated for a range of excitation energies, pulse lengths, mirror reflectivities and absorption, scattering and reflection losses. A linear dependence of output energy on excitation energy is expected only for a vanishingly small pulse length. The effects of localized losses such as those from reflections at the ends of the crystal are similar to scattering losses distributed through the crystal. The output mirror reflectivity giving maximum output energy falls as the excitation energy and scattering increase but is typically 50-60%. The reduction in output caused by scattering is less for lower reflectivities. The angular distribution of light scattered from the ruby when lasing is measured by varying the resonator length to assess the scattering. The predictions of output energy are in good agreement with experiment for all the excitation energies, introduced scattering losses, and mirror reflectivities tri d, except that above 70% reflectivity the prediction is up to 60% low. Possible reasons for this discrepancy are discussed. It was also found experimentally that the resonances between the ends of the ruby are suppressed when lasing, probably due to the optical inhomogeneities produced by the refractive index changes associated with the population changes during a laser spike. The output energy is thus reduced when the ends are not aligned in the resonator. These dynamic inhomogeneities are thought to override any static inhomogeneities already present in the crystal and are a major source of resonator loss.

  2. Bistatic scattering from a three-dimensional object above a two-dimensional randomly rough surface modeled with the parallel FDTD approach. (United States)

    Guo, L-X; Li, J; Zeng, H


    We present an investigation of the electromagnetic scattering from a three-dimensional (3-D) object above a two-dimensional (2-D) randomly rough surface. A Message Passing Interface-based parallel finite-difference time-domain (FDTD) approach is used, and the uniaxial perfectly matched layer (UPML) medium is adopted for truncation of the FDTD lattices, in which the finite-difference equations can be used for the total computation domain by properly choosing the uniaxial parameters. This makes the parallel FDTD algorithm easier to implement. The parallel performance with different number of processors is illustrated for one rough surface realization and shows that the computation time of our parallel FDTD algorithm is dramatically reduced relative to a single-processor implementation. Finally, the composite scattering coefficients versus scattered and azimuthal angle are presented and analyzed for different conditions, including the surface roughness, the dielectric constants, the polarization, and the size of the 3-D object.

  3. Neutron Angular Scatter Effects in 3DHZETRN: Quasi-Elastic (United States)

    Wilson, John W.; Werneth, Charles M.; Slaba, Tony C.; Badavi, Francis F.; Reddell, Brandon D.; Bahadori, Amir A.


    The current 3DHZETRN code has a detailed three dimensional (3D) treatment of neutron transport based on a forward/isotropic assumption and has been compared to Monte Carlo (MC) simulation codes in various geometries. In most cases, it has been found that 3DHZETRN agrees with the MC codes to the extent they agree with each other. However, a recent study of neutron leakage from finite geometries revealed that further improvements to the 3DHZETRN formalism are needed. In the present report, angular scattering corrections to the neutron fluence are provided in an attempt to improve fluence estimates from a uniform sphere. It is found that further developments in the nuclear production models are required to fully evaluate the impact of transport model updates. A model for the quasi-elastic neutron production spectra is therefore developed and implemented into 3DHZETRN.

  4. Absorbing aerosol radiative effects in the limb-scatter viewing geometry

    Directory of Open Access Journals (Sweden)

    A. Wiacek


    Full Text Available The limb-scatter satellite viewing geometry is well suited to detecting low-concentration aerosols in the upper troposphere due to its long observation path length (~200 km, high vertical resolution (~1–2 km and good geographic coverage. We use the fully three-dimensional radiative transfer code SASKTRAN to simulate the sensitivity of limb-scatter viewing Odin/OSIRIS satellite measurements to absorbing mineral dust and carbonaceous aerosols (smoke and pure soot, as well as to non-absorbing sulfate aerosols and ice in the upper troposphere. At long wavelengths (813 nm the addition of all aerosols (except soot to an air only atmosphere produced a radiance increase as compared to air only, on account of the low Rayleigh scattering in air only at 813 nm. The radiance reduction due to soot aerosol was negligible ( At short wavelengths (337, 377, 452 nm, we found that the addition of any aerosol species to an air only atmosphere caused a decrease in single-scattered radiation due to an extinction of Rayleigh scattering in the direction of OSIRIS. The reduction was clearly related to particle size first, with absorption responsible for second-order effects only. Multiple-scattered radiation could either increase or decrease in the presence of an aerosol species, depending both on particle size and absorption. Large scatterers (ice, mineral dust all increased multiple-scattered radiation within, below and above the aerosol layer. Small, highly absorbing pure soot particles produced a negligible multiple-scattering response ( At short wavelengths, the combined effect of single scattering decreases and multiple scattering increases led to complex total radiance signatures that generally could not unambiguously distinguish absorbing versus non-absorbing aerosols. Smoke aerosols led to a total radiance decrease (as compared to air only at all altitudes above the aerosol layer (15–100 km. This unique signature was a result of the aerosols' strong

  5. On the effects of systematic errors in analysis of nuclear scattering data.

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, M.T.; Steward, C.; Amos, K.; Allen, L.J.


    The effects of systematic errors on elastic scattering differential cross-section data upon the assessment of quality fits to that data have been studied. Three cases are studied, namely the differential cross-section data sets from elastic scattering of 200 MeV protons from {sup 12}C, of 350 MeV {sup 16}O-{sup 16}O scattering and of 288.6 MeV {sup 12}C-{sup 12}C scattering. First, to estimate the probability of any unknown systematic errors, select sets of data have been processed using the method of generalized cross validation; a method based upon the premise that any data set should satisfy an optimal smoothness criterion. In another case, the S function that provided a statistically significant fit to data, upon allowance for angle variation, became overdetermined. A far simpler S function form could then be found to describe the scattering process. The S functions so obtained have been used in a fixed energy inverse scattering study to specify effective, local, Schroedinger potentials for the collisions. An error analysis has been performed on the results to specify confidence levels for those interactions. 19 refs., 6 tabs., 15 figs.

  6. Empirical forward scattering phase functions from 0.08 to 16 deg. for randomly shaped terrigenous 1-21 microm sediment grains. (United States)

    Agrawal, Y C; Mikkelsen, Ole A


    We present in-water forward scattering phase functions covering the angle range 0.08 to 16 degrees for 19 narrow-sized dispersions of randomly shaped sediment grains. These dispersions cover particle size range from 1 to 20 microns. These phase functions offer a realistic alternative to Mie theory. Qualitatively, (i) the magnitude of phase functions at the smallest angles for equal size spheres and randomly shaped particles are nearly equal; (ii) the oscillations predicted by Mie theory for spheres disappear for random shaped grains, and (iii) the tendency of phase functions of large spheres to merge at large angles is also seen with randomly shaped grains. The data are also provided in tabulated form.

  7. Electron pitch-angle diffusion: resonant scattering by waves vs. nonadiabatic effects

    Directory of Open Access Journals (Sweden)

    A. V. Artemyev


    Full Text Available In this paper we investigate the electron pitch-angle diffusion coefficients in the night-side inner magnetosphere around the geostationary orbit (L ~ 7 due to magnetic field deformation. We compare the effects of resonant wave–particle scattering by lower band chorus waves and the adiabaticity violation of electron motion due to the strong curvature of field lines in the vicinity of the equator. For a realistic magnetic field configuration, the nonadiabatic effects are more important than the wave–particle interactions for high energy (> 1 MeV electrons. For smaller energy, the scattering by waves is more effective than nonadiabatic one. Moreover, the role of nonadiabatic effects increases with particle energy. Therefore, to model electron scattering and transport in the night-side inner magnetosphere, it is important to take into account the peculiarities of high-energy electron dynamics.

  8. Ptychography: early history and 3D scattering effects (United States)

    Rodenburg, J. M.


    The coherent diffractive imaging method of ptychography is first reviewed from a general historical perspective. Much more recent progress in extending the method to the 3D scattering geometry and the super-resolution configuration is also described. Ptychography was originally conceived by Walter Hoppe as a solution to the X-ray or electron crystallography phase problem. Although the existence of this type of phase information was clearly evident in the early 1970s, the technique was not implemented at atomic-scale wavelengths until the 1990s, and then only in a way that was computationally inefficient, especially in view of the limited size of computers at that time. Fast and efficient ptychographic algorithms were developed much later, in the mid-2000s. The extremes of crystallography ptychography, which only requires two diffraction patterns, and the Wigner Distribution Deconvolution (WDDC) method, which needs a diffraction pattern for every pixel of the final reconstruction, are described. Very recent work relating to the application of serial iterative to 3D inversion are also described.

  9. Neutron scattering effects on fusion ion temperature measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, Lee (Bechtel/Nevada, Las Vegas, NV); Starner, Jason R.; Cooper, Gary Wayne; Ruiz, Carlos L.; Franklin, James Kenneth (Ktech Corporation, Albuquerque, NM); Casey, Daniel T.


    To support the nuclear fusion program at Sandia National Laboratories (SNL), a consistent and verifiable method to determine fusion ion temperatures needs to be developed. Since the fusion temperature directly affects the width in the spread of neutron energies produced, a measurement of the neutron energy width can yield the fusion temperature. Traditionally, the spread in neutron energies is measured by using time-of-flight to convert a spread in neutron energies at the source to a spread in time at detector. One potential obstacle to using this technique at the Z facility at SNL is the need to shield the neutron detectors from the intense bremsstrahlung produced. The shielding consists of eight inches of lead and the concern is that neutrons will scatter in the lead, artificially broaden the neutron pulse width and lead to an erroneous measurement. To address this issue, experiments were performed at the University of Rochester's Laboratory for Laser Energetics, which demonstrated that a reliable ion temperature measurement can be achieved behind eight inches of lead shielding. To further expand upon this finding, Monte Carlo N-Particle eXtended (MCNPX) was used to simulate the experimental geometric conditions and perform the neutron transport. MCNPX was able to confidently estimate results observed at the University of Rochester.

  10. Estimates of the Spectral Aerosol Single Sea Scattering Albedo and Aerosol Radiative Effects during SAFARI 2000 (United States)

    Bergstrom, Robert W.; Pilewskie, Peter; Schmid, Beat; Russell, Philip B.


    Using measurements of the spectral solar radiative flux and optical depth for 2 days (24 August and 6 September 2000) during the SAFARI 2000 intensive field experiment and a detailed radiative transfer model, we estimate the spectral single scattering albedo of the aerosol layer. The single scattering albedo is similar on the 2 days even though the optical depth for the aerosol layer was quite different. The aerosol single scattering albedo was between 0.85 and 0.90 at 350 nm, decreasing to 0.6 in the near infrared. The magnitude and decrease with wavelength of the single scattering albedo are consistent with the absorption properties of small black carbon particles. We estimate the uncertainty in the single scattering albedo due to the uncertainty in the measured fractional absorption and optical depths. The uncertainty in the single scattering albedo is significantly less on the high-optical-depth day (6 September) than on the low-optical-depth day (24 August). On the high-optical-depth day, the uncertainty in the single scattering albedo is 0.02 in the midvisible whereas on the low-optical-depth day the uncertainty is 0.08 in the midvisible. On both days, the uncertainty becomes larger in the near infrared. We compute the radiative effect of the aerosol by comparing calculations with and without the aerosol. The effect at the top of the atmosphere (TOA) is to cool the atmosphere by 13 W/sq m on 24 August and 17 W/sq m on 6 September. The effect on the downward flux at the surface is a reduction of 57 W/sq m on 24 August and 200 W/sq m on 6 September. The aerosol effect on the downward flux at the surface is in good agreement with the results reported from the Indian Ocean Experiment (INDOEX).

  11. A Mixed Effects Randomized Item Response Model (United States)

    Fox, J.-P.; Wyrick, Cheryl


    The randomized response technique ensures that individual item responses, denoted as true item responses, are randomized before observing them and so-called randomized item responses are observed. A relationship is specified between randomized item response data and true item response data. True item response data are modeled with a (non)linear…


    Energy Technology Data Exchange (ETDEWEB)

    Kitzmann, D., E-mail: [Center for Space and Habitability, University of Bern, Sidlerstr. 5, 3012 Bern (Switzerland)


    Carbon dioxide ice clouds are thought to play an important role for cold terrestrial planets with thick CO{sub 2} dominated atmospheres. Various previous studies showed that a scattering greenhouse effect by carbon dioxide ice clouds could result in a massive warming of the planetary surface. However, all of these studies only employed simplified two-stream radiative transfer schemes to describe the anisotropic scattering. Using accurate radiative transfer models with a general discrete ordinate method, this study revisits this important effect and shows that the positive climatic impact of carbon dioxide clouds was strongly overestimated in the past. The revised scattering greenhouse effect can have important implications for the early Mars, but also for planets like the early Earth or the position of the outer boundary of the habitable zone.

  13. Low frequency sound scattering from spherical assemblages of bubbles using effective medium theory. (United States)

    Hahn, Thomas R


    The determination of the acoustic field scattered by an underwater assembly of gas bubbles or similar resonant monopole scatterers is of considerable theoretical and practical interest. This problem is addressed from a theoretical point of view within the framework of the effective medium theory for the case of spherically shaped assemblages. Although being valid more generally, the effective medium theory is an ideal instrument to study multiple scattering effects such as low frequency collective resonances, acoustically coupled breathing modes of the entire assembly. Explicit expressions for the scattering amplitude and cross sections are derived, as well as closed form expressions for the resonance frequency and spectral shape of the fundamental collective mode utilizing analytical S-matrix methods. This approach allows, in principle, a simultaneous inversion for the assembly radius and void fraction directly from the scattering cross sections. To demonstrate the validity of the approach, the theory is applied to the example of idealized, spherically shaped schools of swim bladder bearing fish. The analytic results of the theory are compared to numerical first-principle benchmark computations and excellent agreement is found, even for densely packed schools and frequencies across the bladder resonance.

  14. Elements of QED-NRQED effective field theory: NLO scattering at leading power (United States)

    Dye, Steven P.; Gonderinger, Matthew; Paz, Gil


    The proton radius puzzle, i.e. the large discrepancy in the extraction of the proton charge radius between regular and muonic hydrogen, challenges our understanding of the structure of the proton. It can also be an indication of a new force that couples to muons, but not to electrons. An effective field theory analysis using nonrelativistic quantum electrodynamics (NRQED) indicates that the muonic hydrogen result can be interpreted as a large, compared to some model estimates, muon-proton spin-independent contact interaction. The muonic hydrogen result can be tested by a muon-proton scattering experiment, MUSE, that is planned at the Paul Scherrer Institute in Switzerland. The typical momenta of the muons in this experiment are of the order of the muon mass. In this energy regime the muons are relativistic but the protons are still nonrelativistic. The interaction between the muons and protons can be described by a hybrid QED-NRQED effective field theory. We present some elements of this effective field theory. In particular we consider O (Z α ) scattering up to power m2/M2 , where m (M ) is the muon (proton) mass and Z =1 for a proton, and O (Z2α2) scattering at leading power. We show how the former reproduces Rosenbluth scattering up to power m2/M2 and the latter the relativistic scattering off a static potential. Proton structure corrections at O (Z2α2) will be considered in a subsequent paper.

  15. Variational Effective Index Method for 3D Vectorial Scattering Problems in Photonics: TE Polarization

    NARCIS (Netherlands)

    Ivanova, Alyona; Stoffer, Remco; Kauppinen, L.J.; Hammer, Manfred


    In order to reduce the computational effort we develop a method for 3D-to-2D dimensionality reduction of scattering problems in photonics. Contrary to the `standard' Effective Index Method the effective parameters of the reduced problem are always rigorously defined using the variational technique,

  16. Effect of magnetic impurity scattering in a d-wave superconductor

    CERN Document Server

    Choi, C H


    We study the effect of magnetic impurity scattering in a d-wave superconductor by taking into account the magnetic moment and the anisotropy of the impurity potential. We compute the transition temperate, the superfluid density, the residual resistivity, and the residual density of states as a function of the impurity concentration by solving the t-matrix equation of impurity scattering. In the Ginzburg-Landau region, we derive the general expression for the various physical quantities to discuss the effect of arbitrary phase shifts of the impurity potential. We also compare the results with the experiments for Zn and Ni substitutions in the high temperature superconductors.

  17. Neutron Scattering Studies of Pre-Transitional Effects in Solid-Solid Phase Transformations

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, S. M.


    Neutron scattering studies have played a fundamental role in understanding solid-solid phase transformations, particularly in studying the lattice dynamical behavior associated with precursor effects. A review of the studies performed on solids exhibiting Martensitic transformations is given below. The mode softening and associated elastic diffuse scattering, previously observed in NiAl alloys, will be discussed as well as more recent work on Ni{sub 2}MnGa, a system exhibiting magnetic order as well as a Martensitic transformation. Also, new results on the precursor effects in ordered and disordered FePt alloys will be presented.

  18. Interfacial scattering effect on anomalous Hall effect in Ni/Au multilayers

    KAUST Repository

    Zhang, Qiang


    The effect of interfacial scattering on anomalous Hall effect (AHE) was studied in the ${{\\\\left(\\\\text{N}{{\\\\text{i}}_{\\\\frac{36}{n}~\\\\text{nm}}}/\\\\text{A}{{\\\\text{u}}_{\\\\frac{12}{n}~\\\\text{nm}}}\\ ight)}_{n}}$ multilayers. Field-dependent Hall resistivity was measured in the temperature range of 5–300 K with the magnetic field up to 50 kOe. The anomalous Hall resistivity (${{\\ ho}_{\\\\text{AHE}}}$ ) was enhanced by more than six times at 5 K from n  =  1 to n  =  12 due to the increased interfacial scattering, whereas the longitudinal resistivity (${{\\ ho}_{xx}}$ ) was increased nearly three times. A scaling relation ${{\\ ho}_{\\\\text{AHE}}}\\\\sim \\ ho _{xx}^{\\\\gamma}$ with $\\\\gamma =1.85$ was obtained for ${{\\ ho}_{\\\\text{AHE}}}$ and ${{\\ ho}_{xx}}$ measured at 5 K, indicating that the dominant mechanism(s) of the AHE in these multilayers should be side-jump or/and intrinsic in nature. The new scaling relation ${{\\ ho}_{\\\\text{AHE}}}=\\\\alpha {{\\ ho}_{xx0}}+\\\\beta \\ ho _{xx0}^{2}+b\\ ho _{xx}^{2}$ (Tian et al 2009 Phys. Rev. Lett. 103 087206) has been applied to our data to identify the origin of the AHE in this type of multilayer.

  19. Interfacial scattering effect on anomalous Hall effect in Ni/Au multilayers (United States)

    Zhang, Qiang; Li, Peng; Wen, Yan; He, Xin; Zhao, Yuelei; Zhang, Junli; Zhang, Xixiang


    The effect of interfacial scattering on anomalous Hall effect (AHE) was studied in the {≤ft(\\text{N}{{\\text{i}}\\frac{36{n}~\\text{nm}}}/\\text{A}{{\\text{u}}\\frac{12{n}~\\text{nm}}}\\right)}n} multilayers. Field-dependent Hall resistivity was measured in the temperature range of 5-300 K with the magnetic field up to 50 kOe. The anomalous Hall resistivity ({{ρ\\text{AHE}} ) was enhanced by more than six times at 5 K from n  =  1 to n  =  12 due to the increased interfacial scattering, whereas the longitudinal resistivity ({ρxx} ) was increased nearly three times. A scaling relation {ρ\\text{AHE}}˜ ρ xxγ with γ =1.85 was obtained for {ρ\\text{AHE}} and {ρxx} measured at 5 K, indicating that the dominant mechanism(s) of the AHE in these multilayers should be side-jump or/and intrinsic in nature. The new scaling relation {ρ\\text{AHE}}=α {ρxx0}+β ρ xx02+bρ xx2 (Tian et al 2009 Phys. Rev. Lett. 103 087206) has been applied to our data to identify the origin of the AHE in this type of multilayer.

  20. Effects of Hot-Spot Geometry on Backscattering and Down-Scattering Neutron Spectra (United States)

    Mohamed, Z. L.; Mannion, O. M.; Forrest, C. J.; Knauer, J. P.; Anderson, K. S.; Radha, P. B.


    The measured neutron spectrum produced by a fusion experiment plays a key role in inferring observable quantities. One important observable is the areal density of an implosion, which is inferred by measuring the scattering of neutrons. This project seeks to use particle-transport simulations to model the effects of hot-spot geometry on backscattering and down-scattering neutron spectra along different lines of sight. Implosions similar to those conducted at the Laboratory of Laser Energetics are modeled by neutron transport through a DT plasma and a DT ice shell using the particle transport codes MCNP and IRIS. Effects of hot-spot geometry are obtained by ``detecting'' scattered neutrons along different lines of sight. This process is repeated for various hot-spot geometries representing known shape distortions between the hot spot and the shell. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  1. Morphology effect on the light scattering and dynamic response of polymer network liquid crystal phase modulator. (United States)

    Xiangjie, Zhao; Cangli, Liu; Jiazhu, Duan; Jiancheng, Zeng; Dayong, Zhang; Yongquan, Luo


    Polymer network liquid crystal (PNLC) was one of the most potential liquid crystal for submillisecond response phase modulation, which was possible to be applied in submillisecond response phase only spatial light modulator. But until now the light scattering when liquid crystal director was reoriented by external electric field limited its phase modulation application. Dynamic response of phase change when high voltage was applied was also not elucidated. The mechanism that determines the light scattering was studied by analyzing the polymer network morphology by SEM method. Samples were prepared by varying the polymerization temperature, UV curing intensity and polymerization time. The morphology effect on the dynamic response of phase change was studied, in which high voltage was usually applied and electro-striction effect was often induced. The experimental results indicate that the polymer network morphology was mainly characterized by cross linked single fibrils, cross linked fibril bundles or even both. Although the formation of fibril bundle usually induced large light scattering, such a polymer network could endure higher voltage. In contrast, although the formation of cross linked single fibrils induced small light scattering, such a polymer network cannot endure higher voltage. There is a tradeoff between the light scattering and high voltage endurance. The electro-optical properties such as threshold voltage and response time were taken to verify our conclusion. For future application, the monomer molecular structure, the liquid crystal solvent and the polymerization conditions should be optimized to generate optimal polymer network morphology.

  2. Modeling fluctuations in scattered waves

    CERN Document Server

    Jakeman, E


    Fluctuations in scattered waves limit the performance of imaging and remote sensing systems that operate on all wavelengths of the electromagnetic spectrum. To better understand these fluctuations, Modeling Fluctuations in Scattered Waves provides a practical guide to the phenomenology, mathematics, and simulation of non-Gaussian noise models and discusses how they can be used to characterize the statistics of scattered waves.Through their discussion of mathematical models, the authors demonstrate the development of new sensing techniques as well as offer intelligent choices that can be made for system analysis. Using experimental results and numerical simulation, the book illustrates the properties and applications of these models. The first two chapters introduce statistical tools and the properties of Gaussian noise, including results on phase statistics. The following chapters describe Gaussian processes and the random walk model, address multiple scattering effects and propagation through an extended med...

  3. Effect of static scatterers in laser speckle contrast imaging: an experimental study on correlation and contrast. (United States)

    Vaz, Pedro Guilherme; Humeau-Heurtier, Anne; Figueiras, Edite; Correia, Carlos; Cardoso, Joao M R


    Laser speckle contrast imaging (LSCI) is a non-invasive microvascular blood flow assessment technique with good temporal and spatial resolutions. Most LSCI systems, including commercials devices, can only perform qualitative blood flow evaluation which is a major limitation of this technique. There are several factors that prevent LSCI to be a quantitative technique. Among these factors we can highlight the effect of static scatterers. The goal of this work was to study the influence of different static and dynamic scatterers concentrations on laser speckle correlation and contrast. In order to achieve this, a laser speckle prototype was developed and tested using an optical phantom with different concentrations of static and dynamic scatterers. It has been found that the laser speckle correlation can be used to estimate the relative concentration of static/dynamic scatterers within a sample. Moreover, the speckle correlation proved to be independent of the dynamic scatterers velocity which is a fundamental characteristic to be used as contrast correction method. Creative Commons Attribution license.

  4. Study of effective atomic number of breast tissues determined using the elastic to inelastic scattering ratio

    Energy Technology Data Exchange (ETDEWEB)

    Antoniassi, M.; Conceicao, A.L.C. [Departamento de Fisica e Matematica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil); Poletti, M.E., E-mail: [Departamento de Fisica e Matematica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil)


    In this work we have measured Compton and Rayleigh scattering radiation from normal (adipose and fibroglandular), benign (fibroadenoma) and malignant (ductal carcinoma) breast tissues using a monoenergetic beam of 17.44 keV and a scattering angle of 90{sup o} (x=0.99 A{sup -1}). A practical method using the area of Rayleigh and Compton scattering was used for determining the effective atomic number (Z{sub eff}) of the samples, being validated through measurements of several reference materials. The results show that there are differences in the distributions of Z{sub eff} of breast tissues, which are mainly related to the elemental composition of carbon (Z=6) and oxygen (Z=8) of each tissue type. The results suggest that is possible to use the method to characterize the breast tissues permitting study histological features of the breast tissues related to their elemental composition.

  5. Efimov effect for heteronuclear three-body systems at positive scattering length and finite temperature (United States)

    Emmons, Samuel B.; Kang, Daekyoung; Acharya, Bijaya; Platter, Lucas


    We study the recombination process of three atoms scattering into an atom and diatomic molecule in heteronuclear mixtures of ultracold atomic gases with large and positive interspecies scattering length at finite temperature. We calculate the temperature dependence of the three-body recombination rates by extracting universal scaling functions that parametrize the energy dependence of the scattering matrix. We compare our results to experimental data for the 40K-87Rb mixture and make a prediction for 6Li-87Rb . We find that contributions from higher partial wave channels significantly impact the total rate and, in systems with particularly large mass imbalance, can even obliterate the recombination minima associated with the Efimov effect.

  6. Study of effective atomic number of breast tissues determined using the elastic to inelastic scattering ratio (United States)

    Antoniassi, M.; Conceição, A. L. C.; Poletti, M. E.


    In this work we have measured Compton and Rayleigh scattering radiation from normal (adipose and fibroglandular), benign (fibroadenoma) and malignant (ductal carcinoma) breast tissues using a monoenergetic beam of 17.44 keV and a scattering angle of 90° ( x=0.99 Å -1). A practical method using the area of Rayleigh and Compton scattering was used for determining the effective atomic number ( Zeff) of the samples, being validated through measurements of several reference materials. The results show that there are differences in the distributions of Zeff of breast tissues, which are mainly related to the elemental composition of carbon ( Z=6) and oxygen ( Z=8) of each tissue type. The results suggest that is possible to use the method to characterize the breast tissues permitting study histological features of the breast tissues related to their elemental composition.

  7. Applying Randomness Effectively Based on Random Forests for Classification Task of Datasets of Insufficient Information

    Directory of Open Access Journals (Sweden)

    Hyontai Sug


    Full Text Available Random forests are known to be good for data mining of classification tasks, because random forests are robust for datasets having insufficient information possibly with some errors. But applying random forests blindly may not produce good results, and a dataset in the domain of rotogravure printing is one of such datasets. Hence, in this paper, some best classification accuracy based on clever application of random forests to predict the occurrence of cylinder bands in rotogravure printing is investigated. Since random forests could generate good results with an appropriate combination of parameters like the number of randomly selected attributes for each split and the number of trees in the forests, an effective data mining procedure considering the property of the target dataset by way of trial random forests is investigated. The effectiveness of the suggested procedure is shown by experiments with very good results.

  8. Effects of nonlinear phase modulation on quantum frequency conversion using four-wave mixing Bragg scattering

    DEFF Research Database (Denmark)

    Andersen, Lasse Mejling; McKinstrie, C. J.; Rottwitt, Karsten


    Recently, we solved the coupled-mode equations for Bragg scattering (BS) in the low- and high-conversion regimes, but without the effects of nonlinear phase modulation (NPM). We now present solutions and Green functions in the low-conversion regime that include NPM. We find that NPM does not change...


    Directory of Open Access Journals (Sweden)

    V. I. Egorov


    Full Text Available A scheme of a single photon source for quantum informatics applications based on the spontaneous parametric scattering effect is proposed and a quantum cryptography setup using it is presented. The system is compared to the alternative ones that operate with attenuated classic light.

  10. Transverse spin effects in proton-proton scattering and $Q \\bar Q$ production


    Goloskokov, S. V.


    We discuss transverse spin effects caused by the spin-flip part of the Pomeron coupling with the proton. The predicted spin asymmetries in proton-proton scattering and QQ production in proton-proton and lepton-proton reactions are not small and can be studied in future polarized experiments.

  11. Concentrating or scattering management in agricultural landscapes : Examining the effectiveness and efficiency of conservation measures

    NARCIS (Netherlands)

    Hammers, Martijn; Muskens, Gerard; Van Kats, Ruud J. M.; Teunissen, Wolf A.; Kleijn, David


    A key issue in conservation is where and how much management should be implemented to obtain optimal biodiversity benefits. Cost-effective conservation requires knowledge on whether biodiversity benefits are higher when management is concentrated in a few core areas or scattered across the

  12. Effects of scatter and attenuation correction on quantitative assessment of regional cerebral blood flow with SPECT. (United States)

    Iida, H; Narita, Y; Kado, H; Kashikura, A; Sugawara, S; Shoji, Y; Kinoshita, T; Ogawa, T; Eberl, S


    Appropriate corrections for scatter and attenuation correction are prerequisites for quantitative SPECT studies. However, in most cerebral SPECT studies, uniform attenuation in the head is assumed, and scatter is usually neglected. This study evaluated the effect of attenuation correction and scatter correction on quantitative values and image contrast. Studies were performed in six normal volunteers (ages 22-26 yr) following intravenous 123I-IMP administration using a rotating, dual-head gamma camera. A transmission scan was acquired with a 99mTc rod source (74 MBq) placed at the focus of a symmetrical fanbeam collimator. Data were reconstructed using two attenuation coefficient (mu) maps: quantitative mu map from the transmission scan and a uniform mu map generated by edge detection of the reconstructed images. Narrow and broad beam mu values were used with and without scatter correction, respectively. Scatter was corrected with transmission-dependent convolution subtraction and triple-energy window techniques. Quantitative rCBF images were calculated by the previously validated IMP-autoradiographic technique, and they were compared with those obtained by (15)O-water and PET. SPECT and PET images were registered to MRI studies, and rCBF values were compared in 39 ROIs selected on MRI. Clear differences were observed in rCBF images between the measured and constant mu maps in the lower slices due to the airways and in the higher slices due to increased skull attenuation. However, differences were white matter regions by 10%-20% after scatter correction, increasing gray-to-white ratio to be close to that of PET measurement. The rCBF values from the two scatter correction were not significantly different, but the triple-energy window technique suffered from increased noise. After scatter correction, rCBF values were in good agreement with those measured by PET. This study shows little loss in accuracy results from assuming uniform mu map. However, scatter correction

  13. Alpha alpha scattering in halo effective field theory

    NARCIS (Netherlands)

    Higa, R.; Hammer, H. -W.; van Kolck, U.


    We study the two-alpha-particle (alpha alpha) system in an Effective Field Theory (EFT) for halo-like systems. We propose a power Counting that incorporates the subtle interplay of strong and electromagnetic forces leading to a narrow resonance at an energy of about 0.1 MeV. We investigate the EFT

  14. Scattering and Diffraction of Electromagnetic Radiation: An Effective Probe to Material Structure (United States)

    Xu, Yu-Lin


    scattered intensities are cross sections, such as for extinction, scattering, absorption, and radiation pressure, as a critical type of key quantity addressed in most theoretical and experimental studies of radiative scattering. Cross sections predicted from different scattering theories are supposed to be in general agreement. For objects of irregular shape, the GMM-PA solutions can be compared with the highly flexible Discrete Dipole Approximation (DDA) [4,5] when dividing a target to no more than 106 unit cells. Also, there are different ways to calculate the cross sections in the GMM-PA, providing an additional means to examine the accuracy of the numerical solutions and to unveil potential issues concerning the theoretical formulations and numerical aspects. To solve multiple scattering by an assembly of material volumes through classical theories such as the GMM-PA, the radiative properties of the component scatterers, the complex refractive index in particular, must be provided as input parameters. When using a PA to characterize a material body, this involves the use of an adequate theoretical tool, an effective medium theory, to connect Maxwell's phenomenogical theory with the atomistic theory of matter. In the atomic theory, one regards matter as composed of interacting particles (atoms and molecules) embedded in the vacuum [6]. However, the radiative properties of atomic-scaled particles are known to be substantially different from bulk materials. Intensive research efforts in the fields of cluster science and nanoscience attempt to bridge the gap between bulk and atom and to understand the transition from classical to quantum physics. The GMM-PA calculations, which place virtually no restriction on the component-particle size, might help to gain certain insight into the transition.

  15. Direct extraction of nuclear effects in quasielastic scattering on carbon

    CERN Document Server

    Wilkinson, Callum


    The differences between neutrino and antineutrino CCQE cross sections measured on hydrocarbon targets are due to fundamental differences in the cross section, different neutrino and antineutrino fluxes from the same beamline, and the additional interactions on hydrogen for antineutrinos that are absent for neutrinos. In this analysis we correct for the former two differences to extract a constraint on the ratio of the CCQE cross section for free and bound protons from MINERvA and MiniBooNE data. This measures nuclear effects in carbon, and we compare this measurement to models.

  16. Multiple scattering effects with cyclical terms in active remote sensing of vegetated surface using vector radiative transfer theory (United States)

    The energy transport in a vegetated (corn) surface layer is examined by solving the vector radiative transfer equation using a numerical iterative approach. This approach allows a higher order that includes the multiple scattering effects. Multiple scattering effects are important when the optical t...

  17. Combined antenna and localized plasmon resonance in Raman scattering from random arrays of silver-coated, vertically aligned multiwalled carbon nanotubes. (United States)

    Dawson, P; Duenas, J A; Boyle, M G; Doherty, M D; Bell, S E J; Kern, A M; Martin, O J F; Teh, A-S; Teo, K B K; Milne, W I


    The electric field enhancement associated with detailed structure within novel optical antenna nanostructures is modeled using the surface integral equation technique in the context of surface-enhanced Raman scattering (SERS). The antennae comprise random arrays of vertically aligned, multiwalled carbon nanotubes dressed with highly granular Ag. Different types of "hot-spot" underpinning the SERS are identified, but contrasting characteristics are revealed. Those at the outer edges of the Ag grains are antenna driven with field enhancement amplified in antenna antinodes while intergrain hotspots are largely independent of antenna activity. Hot-spots between the tops of antennae leaning towards each other also appear to benefit from antenna amplification.

  18. Effects of target polarization in electron elastic scattering off endohedral A @C60 (United States)

    Dolmatov, V. K.; Amusia, M. Ya.; Chernysheva, L. V.


    We have developed an efficient approximation to describe the low-energy electron elastic scattering off an endohedral fullerene A @CN . It accounts for polarization of A @CN by incoming electrons without reference to complicated details of the electronic structure of CN itself. The developed approach has permitted us to unravel spectacular A @CN polarization effects in low-energy e-+A @CN elastic scattering, particularly the effects due to interelectron interaction between the electrons of both CN and A . We show that contribution of a single atom A remains unscreened by the multiatomic CN despite the fact that the projectile's wavelength is bigger than the size of the target. Inclusion of A and CN polarizability interference leads to violation of the previously predicted phase additivity rule. The partial scattering cross sections acquire prominent Ramsauer-type minima which, however, disappear in the total cross section. The study reveals notable trends in e-+A @CN elastic scattering versus the polarizability of an encapsulated atom. We also predict the existence of certain negative ions A @CN- . We chose Ne, Xe, and Ba as atoms A , and C60 as the endohedral CN, as the case study. The work focuses on a reasonable compromise between the qualitative and quantitative aspects of the problem in general rather than on carrying out detailed calculations for one particular system.

  19. Electron kinetic effects on interferometry, polarimetry and Thomson scattering measurements in burning plasmas (invited)a) (United States)

    Mirnov, V. V.; Brower, D. L.; Hartog, D. J. Den; Ding, W. X.; Duff, J.; Parke, E.


    At anticipated high electron temperatures in ITER, the effects of electron thermal motion on Thomson scattering (TS), toroidal interferometer/polarimeter (TIP), and poloidal polarimeter (PoPola) diagnostics will be significant and must be accurately treated. The precision of the previous lowest order linear in τ = Te/mec2 model may be insufficient; we present a more precise model with τ2-order corrections to satisfy the high accuracy required for ITER TIP and PoPola diagnostics. The linear model is extended from Maxwellian to a more general class of anisotropic electron distributions that allows us to take into account distortions caused by equilibrium current, ECRH, and RF current drive effects. The classical problem of the degree of polarization of incoherent Thomson scattered radiation is solved analytically exactly without any approximations for the full range of incident polarizations, scattering angles, and electron thermal motion from non-relativistic to ultra-relativistic. The results are discussed in the context of the possible use of the polarization properties of Thomson scattered light as a method of Te measurement relevant to ITER operational scenarios.

  20. Electron kinetic effects on interferometry, polarimetry and Thomson scattering measurements in burning plasmas (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Mirnov, V. V.; Hartog, D. J. Den; Duff, J.; Parke, E. [Physics Department, University of Wisconsin - Madison and the Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, Madison, Wisconsin 53706 (United States); Brower, D. L.; Ding, W. X. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States)


    At anticipated high electron temperatures in ITER, the effects of electron thermal motion on Thomson scattering (TS), toroidal interferometer/polarimeter (TIP), and poloidal polarimeter (PoPola) diagnostics will be significant and must be accurately treated. The precision of the previous lowest order linear in τ = T{sub e}/m{sub e}c{sup 2} model may be insufficient; we present a more precise model with τ{sup 2}-order corrections to satisfy the high accuracy required for ITER TIP and PoPola diagnostics. The linear model is extended from Maxwellian to a more general class of anisotropic electron distributions that allows us to take into account distortions caused by equilibrium current, ECRH, and RF current drive effects. The classical problem of the degree of polarization of incoherent Thomson scattered radiation is solved analytically exactly without any approximations for the full range of incident polarizations, scattering angles, and electron thermal motion from non-relativistic to ultra-relativistic. The results are discussed in the context of the possible use of the polarization properties of Thomson scattered light as a method of T{sub e} measurement relevant to ITER operational scenarios.

  1. On the correct estimation of gap fraction: how to remove scattering effects in the gap fraction measurements? (United States)

    Ryu, Y.; Kobayashi, H.; Welles, J.; Norman, J.


    Correct estimation of gap fraction is essential to quantify canopy architectural variables such as leaf area index and clumping index, which mainly control land-atmosphere interactions. However, gap fraction measurements from optical sensors are contaminated by scattered radiation by canopy and ground surface. In this study, we propose a simple invertible bidirectional transmission model to remove scattering effects from gap fraction measurements. The model shows that 1) scattering factor appears highest where leaf area index is 1-2 in non-clumped canopy, 2) relative scattering factor (scattering factor/measured gap fraction) increases with leaf area index, 3) bright land surface (e.g. snow and bright soil) can contribute a significant scattering factor, 4) the scattering factor is not marginal even in highly diffused sky condition. By incorporating the model with LAI2200 data collected in an open savanna ecosystem, we find that the scattering factor causes significant underestimation of leaf area index (25%) and significant overestimation of clumping index (6 %). The results highlight that some LAI-2000-based LAI estimates from around the world may be underestimated, particularly in highly clumped broad-leaf canopies. Fortunately, the importance of scattering could be assessed with software from LICOR, Inc., which will incorporate the scattering model from this study in a post processing mode after data has been collected by a LAI-2000 or LAI-2200.

  2. Possible effect of static surface disorder on diffractive scattering of H2 from Ru(0001): Comparison between theory and experiment. (United States)

    Kroes, G J; Wijzenbroek, Mark; Manson, J R


    Specific features of diffractive scattering of H2 from metal surfaces can serve as fingerprints of the reactivity of the metal towards H2, and in principle theory-experiment comparisons for molecular diffraction can help with the validation of semi-empirical functionals fitted to experiments of sticking of H2 on metals. However, a recent comparison of calculated and Debye-Waller (DW) extrapolated experimental diffraction probabilities, in which the theory was done on the basis of a potential energy surface (PES) accurately describing sticking to Ru(0001), showed substantial discrepancies, with theoretical and experimental probabilities differing by factors of 2 and 3. We demonstrate that assuming a particular amount of random static disorder to be present in the positions of the surface atoms, which can be characterized through a single parameter, removes most of the discrepancies between experiment and theory. Further improvement might be achievable by improving the accuracy of the DW extrapolation, the model of the H2 rotational state distribution in the experimental beams, and by fine-tuning the PES. However, the question of whether the DW model is applicable to attenuation of diffractive scattering in the presence of a sizable van der Waals well (depth ≈ 50 meV) should also receive attention, in addition to the question of whether the amount of static surface disorder effectively assumed in the modeling by us could have been present in the experiments.

  3. Surface potential and morphology mapping to investigate analyte adsorption effects on surface enhanced Raman scattering (SERS). (United States)

    Chatterjee, Abhijit; Gale, David J G; Grebennikov, Dmytro; Whelan, Liam D; Merschrod S, Erika F


    We demonstrate the power of Kelvin probe force microscopy (KPFM) in enabling a comprehensive study of enhancement mechanisms of surface enhanced Raman scattering (SERS) through the correlation of surface electrical and topographical effects. Local electric fields generated on Au/ZnO nanohybrid films impact analyte adsorption, while roughness is linked to hotspot generation. Optimizing the interplay between these two effects yields SERS enhancement factors (EFs) of 106, enabling ppb detection of polycyclic aromatic hydrocarbons (PAHs) in water.

  4. Effects of La Incorporation in Hf Based Dielectric on Leakage Conduction and Carrier Scattering Mechanisms. (United States)

    You, Seung-Won; Lee, Dong Hwi; Nguyen, Manh Cuong; Jeon, Yoon Seok; Tong, Duc-Tai; Bang, Hyun Joon; Jeong, Jae Kyoung; Choi, Rino


    Metal-oxide-semiconductor field effect transistors (MOSFETs) with various doses of La-incorporated in Hafnium-based dielectrics were characterized to evaluate the effect of La on dielectric and device properties. It is found that the Poole-Frenkel emission model could explain our experimental leakage current conduction mechanism reasonably and barrier heights of localized Poole-Frenkel trap sites increase gradually with increasing La incorporation. Cryogenic measurement (from 100 K to 300 K) of MOSFETs reveals that, as the content of La incorporation in the dielectric increases, the more increase of maximum effective mobility has been found at low temperature. It is mainly attributed to the more reduction of phonon scattering due to higher content of La atoms at the interface of dielectric and channel. Though it is relatively small, the existence of La in dielectric reduces coulomb scattering rate as well.

  5. Elastic α-{sup 12}C scattering at low energies in cluster effective field theory

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Shung-Ichi [Sunmoon University, School of Mechanical and ICT Convergence Engineering, Asan, Chungnam (Korea, Republic of)


    The elastic α-{sup 12}C scattering at low energies is studied employing an effective field theory in which the α and {sup 12}C states are treated as elementary-like fields. We discuss scales of the theory in the stellar energy region where the {sup 12}C(α, γ){sup 16}O process occurs, and then obtain an expression of the elastic scattering amplitudes in terms of effective-range parameters. Using experimental data of the phase shifts for l=0,1, 2 channels at low energies, for which the resonance regions are avoided, we fix values of the parameters and find that the phase shifts at the low energies are well reproduced by using three effective-range parameters for each channel. Furthermore, we discuss problems and uncertainties of the present approach when the amplitudes are extrapolated to the stellar energy region. (orig.)

  6. Long-term effect of surface light scattering and glistenings of intraocular lenses on visual function. (United States)

    Hayashi, Ken; Hirata, Akira; Yoshida, Motoaki; Yoshimura, Koichi; Hayashi, Hideyuki


    To investigate the long-term effect of surface light scattering and glistenings of various intraocular lenses (IOLs) on visual function and optical aberrations after cataract surgery. Case-control study. Thirty-five eyes that underwent implantation of a hydrophobic acrylic, silicone, or polymethyl methacrylate (PMMA) IOL more than 10 years ago were recruited. The scattering light intensity of the surface and internal matrix of the optic was measured using Scheimpflug photography. Visual acuity (VA) was measured using VA charts, and contrast VA and that with glare (glare VA) were examined using a contrast sensitivity tester. Ocular higher-order aberrations (HOAs) were measured using a Hartmann-Shack aberrometer. Mean scattering light intensity of the surface and internal matrix of the optic was significantly higher in the acrylic group than in the silicone and PMMA groups (P ocular and internal optic HOAs in the acrylic group. At more than 10 years postoperatively, visual function, including contrast sensitivity, and ocular HOAs were comparable among eyes that received acrylic, silicone, and PMMA IOLs. Surface scattering and glistenings with the acrylic IOLs were not significantly correlated with visual function and optical aberrations. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. K correlations and facet models in diffuse scattering

    NARCIS (Netherlands)

    Hoenders, B.J.; Jakeman, E.; Baltes, H.P.; Steinle, B.


    The angular intensity distribution of radiation scattered by a wide range of random media can be accounted for by assuming effective source amplitude correlations involving modified Bessel functions Kv. We investigate how such correlations can be derived from physical models of stochastic scattering

  8. Effect of Protective Lead Curtains on Scattered Radiation Exposure to the Operator During Ureteroscopy for Stone Disease: A Controlled Trial. (United States)

    Inoue, Takaaki; Komemushi, Atsushi; Murota, Takashi; Yoshida, Takashi; Taguchi, Makoto; Kinoshita, Hidefumi; Matsuda, Tadashi


    To evaluate a reduction in the total radiation dose to the operator during ureteroscopy (URS) for stone disease by using protective lead curtains. Two studies were planned to compare scattered radiation doses without (nonprotective lead curtain [n-LC] group) and with protective lead curtains (lead curtain [LC] group). In study 1, we measured the spatial distribution of the scattered radiation dose using a human phantom simulating URS for stone management for both groups. In study 2, we prospectively randomized patients undergoing treatment for stone disease with URS into n-LC (n = 62) and LC (n = 61) groups. Scattered radiation doses to the operator during URS were recorded. The primary end point was a reduction in the effective dose to the operator. In study 1, there was an 80% reduction in dose at the operator area between the n-LC and the LC groups. In study 2, the mean effective doses to the operator in the n-LC and the LC groups were 0.33 ± 0.85 and 0.08 ± 0.08 µSv (P = .003). The mean doses measured at the neck and waist outside of the lead apron and at the chest inside the lead apron in the n-LC and the LC groups were 2.22 ± 4.56 vs 0.84 ± 0.7 µSv (P = .008), 5.48 ± 12.4 vs 0.76 ± 0.89 µSv (P = .001), and 0.10 ± 0.47 vs 0.00 ± 0.00 µSv (P = .001), respectively. These curtains are useful for protecting the operator from scattered radiation, resulting in a reduction of the total radiation exposure for surgeons performing URS. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Effect of spin-orbit scattering on transport properties of low-dimensional dilute alloys

    Energy Technology Data Exchange (ETDEWEB)

    Heers, Swantje


    bulk in the first part of the thesis. In the third part, we investigate spin-orbit induced effects on thin (001) and (111) copper and gold films with focus on spin-relaxation mechanisms. We consider both symmetric and asymmetric systems, where the asymmetry of the latter ones is created by covering one side of the film with one layer of Zn. For the symmetric films, spin-mixing parameters and momentum- and spin-relaxation times due to scattering at self-adatoms are calculated. Whereas the largest spin-mixing in (111) films has been obtained for the surface states, on the Fermi surfaces of the (001) films spin hot spots occur, which are caused by anticrossings of bands and lead to locally very high spin mixing. In the asymmetric films, the situation is qualitatively different, as the spin-orbit coupling results in a splitting of all bands and the formation of local effective magnetic fields, the so-called spin-orbit fields. The precession of the electron spin around these axes together with momentum scattering, resulting in a change of the precession axis after each scattering event, is known to lead to spin dephasing. Spin-orbit fields for (001) and (111) copper and gold films are presented. Large fields have been obtained for both surface orientations especially for bulk-like states at the outer boundaries of the Brillouin zone. Furthermore, for the (111) surface states, we find a Rashba-splitting which agrees with experiment and previous calculations. (orig.)

  10. Electromagnetic Scattering from Vegetation Canopies. (United States)

    Sarabandi, Kamal

    Satellite-borne imaging radar has been proposed by the remote sensing community as a potential sensor for the acquisition of quantitative information about forested area on a global scale. To achieve this goal, it is necessary to develop retrieved algorithms that can provide reasonable estimate of vegetation biomass, leaf moisture content, and other physical parameters of tree canopies from multifrequency/multipolarization observations of their radar backscattering coefficients. Retrieval algorithms often are called "inverse problem" because their input/output parameters are the inverse of those associated with the direct problem, which in the present case refers to the development of a radar scattering model that relates the radar response to the canopy architecture and associated parameters. This thesis provides electromagnetic solutions to several problems associated with scattering from tree canopies. The forest canopy is modelled in the form of layers comprised of randomly distributed particles with known statistical properties. In Chapters 2-8 effective scattering models for different constituent particles of vegetation canopies are developed by employing appropriate asymptotic solutions and approximations. The effects of various physical features of the particles, such as curvature and variation in thickness for planar leaves and roughness for tree trunks, on their scattering behavior are examined. In Chapter 9 the scattering problem of inhomogeneous layered media is formulated via the vector radiative transfer equations and a first-order solution for the radar scattering coefficients is obtained. The radiative transfer solution is formulated in terms of two sets of input functions: the scattering matrices of the constituent particles, which are given in Chapters 2-8, and the size and orientation distribution functions of the particles. The radar scattering model and associated input functions can be used to conduct sensitivity analyses to determine the

  11. Characterization of Non-Rayleigh Acoustic Scattering by Elongated Scatterers in the Water Column and on Boundaries (United States)


    scatterer randomly located in a beam," submitted to IEEE J. Ocean. Eng. [submitted, refereed] Dissertation Bhatia, S. (2012). "Non-Rayleigh scattering...With beampattern effects 1IJ:1 spheroid. 5 degree grazing incidence with beampattern, kb«lO Norma red ecno ampwtude Figure 9. Echo PFA for

  12. Dynamics of speckles with a small number of scattering events: specific features of manifestation of the Doppler effect. (United States)

    Ulyanov, Sergey S


    Spectra of intensity fluctuations of dynamic non-Gaussian speckles formed with a small number of scattering events have been studied theoretically and experimentally. A new type of manifestation of the Doppler effect has been observed. The dependence of frequency position of the Doppler peak and the shape of the Doppler spectrum on the number of scatterers has been analyzed.

  13. Signatures of medium effects on NN interactions in proton scattering from nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Amos, K.; Dortmans, P.J.; Karataglidis, S.


    Effective two nucleon (NN) interactions in the nuclear medium have been defined from an accurate mapping of NN g matrices obtained by solving the Brueckner-Bethe-Goldstone (BBG) equations for infinite nuclear matter. Those effective interactions have been used in fully microscopic calculations of (nonlocal) effective proton-light nuclei interactions with which we have obtained predictions of the differential cross sections and analysing powers from elastic scattering. Results for incident proton energies of 65 and 200 MeV are considered in particular herein. The relative motion wave functions so found then have been used as the distorted waves in distorted wave approximation (DWA) studies of select inelastic scattering events. The same effective interactions were used as the transition operators in those calculations. The relevant nuclear spectroscopy for the elastic and DWA (p, p`) calculations has been found from full (0+2){Dirac_h}{omega} shell model evaluations of the nuclear structure; wave functions of which give good descriptions for many measured longitudinal, transverse electric and transverse magnetic form factors from electron scattering. 12 refs., 17 figs.

  14. Laser Thomson scattering measurements of electron temperature and density in a hall-effect plasma (United States)

    Washeleski, Robert L.

    Hall-effect thrusters (HETs) are compact electric propulsion devices with high specific impulse used for a variety of space propulsion applications. HET technology is well developed but the electron properties in the discharge are not completely understood, mainly due to the difficulty involved in performing accurate measurements in the discharge. Measurements of electron temperature and density have been performed using electrostatic probes, but presence of the probes can significantly disrupt thruster operation, and thus alter the electron temperature and density. While fast-probe studies have expanded understanding of HET discharges, a non-invasive method of measuring the electron temperature and density in the plasma is highly desirable. An alternative to electrostatic probes is a non-perturbing laser diagnostic technique that measures Thomson scattering from the plasma. Thomson scattering is the process by which photons are elastically scattered from the free electrons in a plasma. Since the electrons have thermal energy their motion causes a Doppler shift in the scattered photons that is proportional to their velocity. Like electrostatic probes, laser Thomson scattering (LTS) can be used to determine the temperature and density of free electrons in the plasma. Since Thomson scattering measures the electron velocity distribution function directly no assumptions of the plasma conditions are required, allowing accurate measurements in anisotropic and non-Maxwellian plasmas. LTS requires a complicated measurement apparatus, but has the potential to provide accurate, non-perturbing measurements of electron temperature and density in HET discharges. In order to assess the feasibility of LTS diagnostics on HETs non-invasive measurements of electron temperature and density in the near-field plume of a Hall thruster were performed using a custom built laser Thomson scattering diagnostic. Laser measurements were processed using a maximum likelihood estimation method

  15. Measurement of effective atomic number of gunshot residues using scattering of gamma rays (United States)

    Yılmaz, Demet; Turşucu, Ahmet; Uzunoğlu, Zeynep; Korucu, Demet


    Better understanding of gunshot residues and the major elemental composition would be valuable to forensic scientists for their analysis work and interpretation of results. In the present work, the effective atomic numbers of gunshot residues (cartridge case, bullet core, bullet jacket and gunpowder) were analyzed using energy dispersive X-ray analysis (EDX). The scattering of 59.54 keV gamma rays is studied using a high-resolution HPGe detector. The experiment is performed on various elements with atomic number in the 4≤Z≤82. The intensity ratio of coherent to Compton scattered peaks, corrected for photo-peak efficiency of gamma detector and absorption of photons in the sample and air, is plotted as a function of atomic number and constituted a best-fit-curve. From this fit-curve, the respective effective atomic numbers of gunshot residues are determined.

  16. Anatomy of QCD Strings and Saturation Effects in High-Energy Scattering


    Shoshi, Arif I.


    We develop a model to compute high-energy reactions of hadrons and photons. The perturbative interaction is described by gluon exchange and the non-perturbative interaction by the stochastic vacuum model which leads to quark-confinement in dipoles via a string of color fields. We study the QCD structure of the dipole-dipole scattering in momentum space focussing especially on interactions between strings. We represent the string as a collection of stringless dipoles, show confinement effects ...

  17. Effects of Mild Curvature on ANCOVA and Randomized Blocks. (United States)

    Klockars, Alan J.; Potter, Nina Salcedo

    The type I error control and power of a number of analysis of covariance (ANCOVA) and randomized block (RB) designs with curvilinear data were studied for tests of the additive treatment effect and interaction. For tests of additive effects, the analysis was also conducted using systematic assignment to treatments and using random assignment with…

  18. Simultaneous Retrieval of Effective Refractive Index and Density from Size Distribution and Light Scattering Data: Weakly-Absorbing Aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Kassianov, Evgueni I.; Barnard, James C.; Pekour, Mikhail S.; Berg, Larry K.; Shilling, John E.; Flynn, Connor J.; Mei, Fan; Jefferson, Anne


    We propose here a novel approach for retrieving in parallel the effective density and real refractive index of weakly absorbing aerosol from optical and size distribution measurements. Here we define “weakly absorbing” as aerosol single-scattering albedos that exceed 0.95 at 0.5 um.The required optical measurements are the scattering coefficient and the hemispheric backscatter fraction, obtained in this work from an integrating nephelometer. The required size spectra come from a Scanning Mobility Particle Sizer and an Aerodynamic Particle Sizer. The performance of this approach is first evaluated using a sensitivity study with synthetically generated but measurement-related inputs. The sensitivity study reveals that the proposed approach is robust to random noise; additionally the uncertainties of the retrieval are almost linearly proportional to the measurement errors, and these uncertainties are smaller for the real refractive index than for the effective density. Next, actual measurements are used to evaluate our approach. These measurements include the optical, microphysical, and chemical properties of weakly absorbing aerosol which are representative of a variety of coastal summertime conditions observed during the Two-Column Aerosol Project (TCAP; The evaluation includes calculating the root mean square error (RMSE) between the aerosol characteristics retrieved by our approach, and the same quantities calculated using the conventional volume mixing rule for chemical constituents. For dry conditions (defined in this work as relative humidity less than 55%) and sub-micron particles, a very good (RMSE~3%) and reasonable (RMSE~28%) agreement is obtained for the retrieved real refractive index (1.49±0.02) and effective density (1.68±0.21), respectively. Our approach permits discrimination between the retrieved aerosol characteristics of sub-micron and sub-10micron particles. The evaluation results also reveal that the

  19. Scattering effects of glass-embedded microstructures by roughness controlled fs-laser micromachining (United States)

    Lo Turco, Sara; Di Donato, Andrea; Criante, Luigino


    We report a full roughness analysis carried out upon the internal walls of fs-fabricated micro-structures embedded in fused silica glass. In addition to the standard mapping methods based on RMS evaluation, we performed a spectral analysis to compare different types of surface morphology. In detail, introducing the correlation length L c as a key parameter to describe the profile periodicity, we highlight that the bottom- top- and side-wall of a square micro-channel show a different surface order and differently affect the light scattering. This is further validated by fast Fourier transform calculations and supported by beam transmission holograms. Here we suggest that proper beam shaping could ensure uniform energy distribution and low scattering effects.

  20. Separating form factor and nuclear model effects in quasielastic neutrino-nucleus scattering (United States)

    Wieske, Joseph


    When studying neutrino oscillations an understanding of charged current quasielastic (CCQE) neutrino-nucleus scattering is imperative. This interaction depends on a nuclear model as well as knowledge of form factors. In the past, CCQE data from the MiniBooNE experiment was analyzed assuming the Relativistic Fermi Gas (RFG) nuclear model, an axial dipole form factor in, and using the the z-expansion for the axial form factor in. We present the first analysis that combines a non-RFG nuclear model, in particular the Correlated Fermi Gas nuclear model (CFG) of, and the z expansion for the axial form factor. This will allow us to separate form factor and nuclear model effects in CCQE scattering. This project was supported through the Wayne State University REU program under NSF Grant PHY-1460853 and by the DOE Grant DE-SC0007983.

  1. Effect of substrate on the results of measuring coating thickness according to radiation scattered by substrate

    Energy Technology Data Exchange (ETDEWEB)

    Nedavnij, O.I.; Khripunov, L.Z. (Tomskij Politekhnicheskij Inst. (USSR). Nauchno-Issledovatel' skij Inst. Ehlektronnoj Introskopii)


    The effect of a substrate on the results of measuring tantalum coating thickness in two-layer compositions according to gamma radiation scattered by the substrate is studied. It is shown that by means of an albedo-radiometer realizing the physical model absorber-scatterer one can determine the thickness (application uniformity) of tantalum coatings up to 150-300 depending on the substrate material (plexiglas, aluminium, iron, copper). In case of testing coatings on substrates of alloys and high-alloy steels in order to ensure high accuracy of measurement it is expedient with the above albedo-radiometer to determine the value of the backscattered radiation flux for the substrate before coating application.

  2. Limits on the effective quark radius from inclusive $ep$ scattering at HERA

    CERN Document Server

    Abramowicz, H; Adamczyk, L; Adamus, M; Antonelli, S; Aushev, V; Behnke, O; Behrens, U; Bertolin, A; Bloch, I; Boos, EG; Brock, I; Brook, NH; Brugnera, R; Bruni, A; Bussey, PJ; Caldwell, A; Capua, M; Catterall, CD; Chwastowski, J; Ciborowski, J; Ciesielski, R; Cooper-Sarkar, AM; Corradi, M; Dementiev, RK; Devenish, RCE; Dusini, S; Foster, B; Gach, G; Gallo, E; Garfagnini, A; Geiser, A; Gizhko, A; Gladilin, LK; Golubkov, Yu A; Grzelak, G; Guzik, M; Hain, W; Hochman, D; Hori, R; Ibrahim, ZA; Iga, Y; Ishitsuka, M; Januschek, F; Jomhari, NZ; Kadenko, I; Kananov, S; Karshon, U; Kaur, P; Kisielewska, D; Klanner, R; Klein, U; Korzhavina, IA; Kotański, A; Kötz, U; Kovalchuk, N; Kowalski, H; Krupa, B; Kuprash, O; Kuze, M; Levchenko, BB; Levy, A; Limentani, S; Lisovyi, M; Lobodzinska, E; Löhr, B; Lohrmann, E; Longhin, A; Lontkovskyi, D; Lukina, OYu; Makarenko, I; Malka, J; Mohamad Idris, F; Mohammad Nasir, N; Myronenko, V; Nagano, K; Nobe, T; Nowak, RJ; Onishchuk, Yu; Paul, E; Perlański, W; Pokrovskiy, NS; Przybycien, M; Roloff, P; Ruspa, M; Saxon, DH; Schioppa, M; Schneekloth, U; Schörner-Sadenius, T; Shcheglova, LM; Shevchenko, R; Shkola, O; Shyrma, Yu; Singh, I; Skillicorn, IO; Słomiński, W; Solano, A; Stanco, L; Stefaniuk, N; Stern, A; Stopa, P; Sztuk-Dambietz, J; Tassi, E; Tokushuku, K; Tomaszewska, J; Tsurugai, T; Turcato, M; Turkot, O; Tymieniecka, T; Verbytskyi, A; Wan Abdullah, WAT; Wichmann, K; Wing, M; Yamada, S; Yamazaki, Y; Zakharchuk, N; Żarnecki, AF; Zawiejski, L; Zenaiev, O; Zhautykov, BO; Zotkin, DS; Bhadra, S; Gwenlan, C; Hlushchenko, O; Polini, A; Mastroberardino, A; Sukhonos, D


    The high-precision HERA data allows searches up to TeV scales for Beyond the Standard Model contributions to electron-quark scattering. Combined measurements of the inclusive deep inelastic cross sections in neutral and charged current $ep$ scattering corresponding to a luminosity of around 1 fb$^{-1}$ have been used in this analysis. A new approach to the beyond the Standard Model analysis of the inclusive $ep$ data is presented; simultaneous fits of parton distribution functions together with contributions of "new physics" processes were performed. Results are presented considering a finite radius of quarks within the quark form-factor model. The resulting 95% C.L. upper limit on the effective quark radius is $0.43\\cdot 10^{-16}$ cm.

  3. Impurity scattering and size quantization effects in a single graphene nanoflake (United States)

    Tesch, Julia; Leicht, Philipp; Blumenschein, Felix; Gragnaniello, Luca; Bergvall, Anders; Löfwander, Tomas; Fonin, Mikhail


    By using Fourier-transform scanning tunneling spectroscopy we measure the interference patterns produced by the impurity scattering of confined Dirac quasiparticles in epitaxial graphene nanoflakes. Upon comparison of the experimental results with tight-binding calculations of realistic model flakes, we show that the characteristic features observed in the Fourier-transformed local density of states are related to scattering between different transverse modes (subbands) of a graphene nanoflake and allow direct insight into the gapped electronic spectrum of graphene. We also observe a strong reduction of quasiparticle lifetime which is attributed to the interaction with the underlying substrate. In addition, we show that the distribution of the on-site energies at flower defects leads to an effectively broken pseudospin selection rule, where intravalley backscattering is allowed.

  4. Limits on the effective quark radius from inclusive ep scattering at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Sciences; Collaboration: ZEUS Collaboration; and others


    The high-precision HERA data allows searches up to TeV scales for Beyond the Standard Model contributions to electron-quark scattering. Combined measurements of the inclusive deep inelastic cross sections in neutral and charged current ep scattering corresponding to a luminosity of around 1 fb{sup -1} have been used in this analysis. A new approach to the beyond the Standard Model analysis of the inclusive ep data is presented; simultaneous fits of parton distribution functions together with contributions of ''new physics'' processes were performed. Results are presented considering a finite radius of quarks within the quark form-factor model. The resulting 95% C.L. upper limit on the effective quark radius is 0.43.10{sup -16} cm.

  5. Transparency Effect of Electrolyte on Light Back-Scattering in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    N. Sharifi


    Full Text Available Conventionally, a film of TiO2 particles of ~300 nm size is employed in DSCs as the back reflector film to enhance the light harvesting. In this study, two electrolytes with different transparencies, iodide-based and cobalt-based electrolytes, were used to investigate the transparency effect of electrolytes on light back-scattering from back scattering layer and also to study its effect on the performance of DSCs. The use of cobalt-based electrolyte is recommended from the view point of optical properties as due to the light absorption in electrolytes, the current density losses are 2.9mA/cm2 and 4.2 mA/cm2 in cobalt- and iodide-based electrolytes, respectively, and the transmission of 100% is observed for cobalt-based electrolyte in 500-600 nm in spite of iodide-based electrolyte. Use of light back-scattering layer, unlike iodide-based cell, causes external quantum efficiency in cobalt-base cell to increase for the wavelengths lower than 350 nm since cobalt-base electrolyte has transparency in this region. In addition, optical calculations demonstrate that in the range 400-500 nm, in which dye has a noticeable absorption, absorption loss is 40% and 30% for iodide- and cobalt-based electrolytes, respectively.

  6. Forward scatter dose effect at metallic interfaces irradiated by X and gamma ray therapy beams. (United States)

    Ravikumar, M; Ravichandran, R; Supe, S S


    In this study forward scattering effects near different metallic interfaces are measured for Co-60 gamma and 6 and 18 MV photon beams. The studied effects are the transport of secondary electrons across the metallic interface and the scattering of photons by the metallic inhomogeneity. All measurements were carried out with a PTW thin-window, parallel plate ionisation chamber (B 23344-036) and an RDM-1F electrometer with digital readout. Thin sheets of aluminium, mild steel, copper, cadmium and lead were used as inhomogeneities. The inhomogeneities were placed between the polystyrene phantom and the front window of the chamber which was maintained at 100 cm SSD. It was noticed that for a high energy photon beam (18 MV) the forward scatter dose factor (FSDF) increases rapidly as the thickness of the metallic inhomogeneity increases. For low energy photons, there is a sharp initial decrease of the FSDF until a minimum value is reached followed by a slow increase with increasing thickness of the inhomogeneity. It was also noted that the FSDF variation at off-axis distances has slightly more slope compared with the ionization ratio (IR) curves for both 6 MV and 18 MV photons. However, the variation in slope is prominent for 18 MV compared with 6 MV photon beam. The sharp dose decrease observed downstream of a metallic inhomogeneity at relatively low photon energies (Co-60, 6 MV) is attributed to the internal scattering of secondary electrons within the metal. The dose enhancement observed for high energy photon beams is attributed to the domination of the pair production process, increasing with atomic number. Since FSDF is dependent on the photon beam spectra, it can be used as a measure of beam quality across the beam.

  7. Normal processes of quasi particles scattering and kinetic effects in semiconductors with degenerated statistic of charge carriers

    CERN Document Server

    Kuliev, I G


    One studied the effect of normal processes of electron-electron and phonon-phonon scattering on relaxation of quasi-particle pulse in nonequilibrium electron-phonon systems of degenerate semiconductors. One solved a system of kinetic equations for electron and phonon functions of distribution and calculated kinetic coefficients degeneration parameter. One analyzed the effect of normal processes of quasi-particle scattering on electric conductivity, thermo-emf and heat conductivity of degenerate semiconductors. One took account of redistribution of phonon pulse in N-processes of phonon-phonon scattering both inside every oscillating particle and between phonon different oscillating branches

  8. Effective actions for high energy scattering in QCD and in gravity

    Directory of Open Access Journals (Sweden)

    Lipatov L. N.


    Full Text Available The scattering amplitudes in QCD and gravity at high energies are described in terms of reggeized gluons and gravitons, respectively. In particular, the BFKL Pomeron in N = 4 SUSY is dual to the reggeized graviton living in the 10-dimensional anti-de-Sitter space. The effective actions for the reggeized gluons and gravitons are local in their rapidities. The Euler-Lagrange equations for these effective theories are constructed and their solutions are used for calculations of corresponding Reggeon vertices and trajectories.

  9. The effective cross section for double parton scattering within a holographic AdS/QCD approach

    Directory of Open Access Journals (Sweden)

    Marco Traini


    Full Text Available A first attempt to apply the AdS/QCD framework for a bottom–up approach to the evaluation of the effective cross section for double parton scattering in proton–proton collisions is presented. The main goal is the analytic evaluation of the dependence of the effective cross section on the longitudinal momenta of the involved partons, obtained within the holographic Soft-Wall model. If measured in high-energy processes at hadron colliders, this momentum dependence could open a new window on 2-parton correlations in a proton.

  10. The effective cross section for double parton scattering within a holographic AdS/QCD approach

    Energy Technology Data Exchange (ETDEWEB)

    Traini, Marco, E-mail: [Institut de Physique Théorique, Université Paris Saclay, CEA, F-91191 Gif-sur-Yvette (France); INFN - TIFPA, Dipartimento di Fisica, Università degli Studi di Trento, Via Sommarive 14, I-38123 Povo, Trento (Italy); Rinaldi, Matteo [Departament de Fisica Teòrica, Universitat de València and Institut de Fisica Corpuscular, Consejo Superior de Investigaciones Científicas, 46100 Burjassot, València (Spain); Scopetta, Sergio [Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Via A. Pascoli, I-06123 (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Perugia (Italy); Vento, Vicente [Departament de Fisica Teòrica, Universitat de València and Institut de Fisica Corpuscular, Consejo Superior de Investigaciones Científicas, 46100 Burjassot, València (Spain)


    A first attempt to apply the AdS/QCD framework for a bottom–up approach to the evaluation of the effective cross section for double parton scattering in proton–proton collisions is presented. The main goal is the analytic evaluation of the dependence of the effective cross section on the longitudinal momenta of the involved partons, obtained within the holographic Soft-Wall model. If measured in high-energy processes at hadron colliders, this momentum dependence could open a new window on 2-parton correlations in a proton.

  11. Seed removal by scatter-hoarding rodents: the effects of tannin and nutrient concentration. (United States)

    Wang, Bo; Yang, Xiaolan


    The mutualistic interaction between scatter-hoarding rodents and seed plants have a long co-evolutionary history. Plants are believed to have evolved traits that influence the foraging behavior of rodents, thus increasing the probability of seed removal and caching, which benefits the establishment of seedlings. Tannin and nutrient content in seeds are considered among the most essential factors in this plant-animal interaction. However, most previous studies used different species of plant seeds, rendering it difficult to tease apart the relative effect of each single nutrient on rodent foraging behavior due to confounding combinations of nutrient contents across seed species. Hence, to further explore how tannin and different nutritional traits of seed affect scatter-hoarding rodent foraging preferences, we manipulated tannin, fat, protein and starch content levels, and also seed size levels by using an artificial seed system. Our results showed that both tannin and various nutrients significantly affected rodent foraging preferences, but were also strongly affected by seed size. In general, rodents preferred to remove seeds with less tannin. Fat addition could counteract the negative effect of tannin on seed removal by rodents, while the effect of protein addition was weaker. Starch by itself had no effect, but it interacted with tannin in a complex way. Our findings shed light on the effects of tannin and nutrient content on seed removal by scatter-hoarding rodents. We therefore, believe that these and perhaps other seed traits should interactively influence this important plant-rodent interaction. However, how selection operates on seed traits to counterbalance these competing interests/factors merits further study. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. The Analysis of Random Effects in Modeling Studies. (United States)

    Scheirer, C. James; Geller, Sanford E.


    Argues that in research on the effects of modeling, models must be analyzed as a random factor in order to avoid a positive bias in the results. The concept of a random factor is discussed, worked examples are provided, and a practical solution to the problem is proposed. (JMB)

  13. Phase-shift effect of amplitude spread function on spectrum and image formation in coherent Raman scattering microspectroscopy. (United States)

    Fukutake, Naoki


    Coherent Raman scattering microspectroscopy, which includes coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) microspectroscopy, permits label-free hyperspectral imaging. We report the theoretical study of the phase-shift effect of the impulse response function on the spectral and image-forming properties of coherent Raman scattering microspectroscopy. We show that the spectrum and image are influenced by not only the NA of objective for excitation (NA(ex)) but also that for signal collection (NA(col)), in association with the phase-shift effect. We discuss that, under the condition NA(ex)≠NA(col), both the spectrum and the image become deformed by the phase-shift effect, which can be applied to the direct measurement of the imaginary part of the nonlinear susceptibility in CARS spectroscopy. We point out that, even in SRS microscopy, the nonresonant background can contribute to the image formation and cause the artifact in the image.

  14. CDCC calculations of elastic scattering for the systems 6Li+144Sm and 6Li+208Pb. Effect of resonances of 6Li on elastic scattering angular distributions (United States)

    Gómez Camacho, A.


    Calculations of elastic scattering angular distributions for reactions of the weakly bound projectile 6Li with targets 144Sm and 208Pb at energies above the barrier, are performed with the Continuum Discretized Coupled-Channel method (CDCC). Ground, resonant and nonresonant continuum states of 6Li are included up to some maximum energy epsilonmax for which convergence is achieved. In the three-body system, global interactions are used for the α-target and d - target sub-systems. The effect of continuum resonant states of 6Li, i.e., l = 2, jπ = 3+, 2+ and 1+ on elastic scattering angular distributions is investigated by extracting these states from the continuum space. It is found that the calculated elastic scattering angular distributions are in good agreement with the measurements for most of the cases studied where consideration of couplings to continuum states is essential. It is also found that the resonance character of the continuum states is in some cases important to obtain agreement with the data.

  15. Effect of compressibility and non-uniformity in flow on the scattering pattern of acoustic cloak. (United States)

    Ryoo, Hyeonbin; Jeon, Wonju


    During the last decade, most of acoustic cloak research has been done within a theoretical framework in which the medium is at rest. However, such an acoustic cloak cannot preserve its unique properties or functions to make an object acoustically invisible in the presence of flow. In this study, we propose a theoretical framework to accurately investigate the effect of compressibility and non-uniformity in flow on the scattering pattern of acoustic cloak. In the formulation, the wave operator is coupled with the non-uniform velocity vector, and the equivalent source terms due to mean flow are divided into the compressibility effect and the non-uniformity effect with their own physical meanings. Numerical simulation shows the difference in far-field directivity between previous and present formulations. The polarity of the equivalent sources in the present formulation shows hexapole and skewed quadrupole patterns for non-uniformity and compressibility effects, respectively, and their magnitudes increase with power laws of Mach number as the Mach number increases. As an application, we make use of the present formulation for predicting the acoustic scattering from newly designed convective cloaks. The simulation results show better performance compared to the existing convective cloak.

  16. Effective inelastic scattering cross-sections for background analysis in HAXPES of deeply buried layers

    Energy Technology Data Exchange (ETDEWEB)

    Risterucci, P., E-mail: [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Université de Lyon, Institut des Nanotechnologies de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark); Renault, O., E-mail: [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Zborowski, C. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Sorbonne Universités, UPMC Univ. Paris 06, CNRS, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005, Paris (France); Université de Lyon, Institut des Nanotechnologies de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark); Bertrand, D.; Torres, A. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Rueff, J.-P. [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, BP 48 91192, Gif-sur-Yvette Cedex (France); Sorbonne Universités, UPMC Univ. Paris 06, CNRS, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005, Paris (France); Ceolin, D. [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, BP 48 91192, Gif-sur-Yvette Cedex (France); Grenet, G. [Université de Lyon, Institut des Nanotechnologies de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Tougaard, S. [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark)


    Highlights: • An effective approach for quantitative background analysis in HAXPES spectra of buried layer underneath complex overlayer structures is proposed. • The approach relies on using a weighted sum of inelastic scattering cross section of the pure layers. • The method is validated by the study of an advanced power transistor stack after successive annealing steps. • The depth distribution of crucial elements (Ti, Ga) is determined reliably at depths up to nearly 50 nm. - Abstract: Inelastic background analysis of HAXPES spectra was recently introduced as a powerful method to get access to the elemental distribution in deeply buried layers or interfaces, at depth up to 60 nm below the surface. However the accuracy of the analysis highly relies on suitable scattering cross-sections able to describe effectively the transport of photoelectrons through overlayer structures consisting of individual layers with potentially very different scattering properties. Here, we show that within Tougaard’s practical framework as implemented in the Quases-Analyze software, the photoelectron transport through thick (25–40 nm) multi-layer structures with widely different cross-sections can be reliably described with an effective cross-section in the form of a weighted sum of the individual cross-section of each layer. The high-resolution core-level analysis partly provides a guide for determining the nature of the individual cross-sections to be used. We illustrate this novel approach with the practical case of a top Al/Ti bilayer structure in an AlGaN/GaN power transistor device stack before and after sucessive annealing treatments. The analysis provides reliable insights on the Ti and Ga depth distributions up to nearly 50 nm below the surface.

  17. Impulsive Light Scattering by Coherent Phonons in LaAlO3: Disorder and Boundary Effects (United States)

    Liu, Y.; Frenkel, A.; Garrett, G. A.; Whitaker, J. F.; Fahy, S.; Uher, C.; Merlin, R.


    Pump-probe measurements of coherent-phonon-induced changes of refractive index in LaAlO3 are dominated by normally weak boundary effects. Atomic displacements in the range 50-500 μÅ were generated and probed by femtosecond laser pulses through impulsive Raman scattering. The absence of a bulk contribution is ascribed to phase mismatch due to domain disorder. Selection rules are consistent with a Raman model considering reflection and transmission at interfaces. Intensities and phonon parameters as a function of temperature agree well with incoherent Raman data.

  18. Covariant spectator theory of $np$ scattering:\\\\ Effective range expansions and relativistic deuteron wave functions

    Energy Technology Data Exchange (ETDEWEB)

    Franz Gross, Alfred Stadler


    We present the effective range expansions for the 1S0 and 3S1 scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with \\chi^2/N{data} \\simeq 1) to the 2007 world np data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A fortran subroutine to compute these wave functions can be obtained from the authors.

  19. Spectral phonon scattering effects on the thermal conductivity of nano-grained barium titanate (United States)

    Donovan, Brian F.; Foley, Brian M.; Ihlefeld, Jon F.; Maria, Jon-Paul; Hopkins, Patrick E.


    We study the effect of grain size on thermal conductivity of thin film barium titanate over temperatures ranging from 200 to 500 K. We show that the thermal conductivity of Barium Titanate (BaTiO3) decreases with decreasing grain size as a result of increased phonon scattering from grain boundaries. We analyze our results with a model for thermal conductivity that incorporates a spectrum of mean free paths in BaTiO3. In contrast to the common gray mean free path assumption, our findings suggest that the thermal conductivity of complex oxide perovskites is driven by a spectrum of phonons with varying mean free paths.

  20. Effect of scattered and discrete hydramethylnon bait placement on the Asian needle ant. (United States)

    Rice, Eleanor Spicer; Shik, Jonathan Z; Silverman, Jules


    The Asian needle ant (Pachycondyla chinensis Emery) is invading natural and disturbed habitats across the eastern United States. While recent studies document the impact of P. chinensis on native ecosystems and human health, effective control measures remain unknown. Thus, we evaluated the field performance of a hydramethylnon granular bait, Maxforce Complete Granular Insect Bait, dispersed in clumps or scattered against P. chinensis. We also measured the effect of this bait on P. chinensis outside of the treatment zone. Surprisingly, unlike reports for other ant species, we achieved nearly complete P. chinensis population reductions 1 d after treatments were applied. Significant ant reductions were achieved until the end of our study at 28 d. No difference was recorded between clumped and scattered application methods. We found no overall difference in ant reductions from the edge out to 5 m beyond the treatment zone. Other local ant species appeared to be unaffected by the bait and foraging activity increased slightly after P. chinensis removal from treated areas. We suggest that Maxforce Complete Granular Insect Bait can be effective in an Asian needle ant treatment program.

  1. Effects of relative humidity on aerosol light scattering: results from different European sites

    Directory of Open Access Journals (Sweden)

    P. Zieger


    Full Text Available The effect of aerosol water uptake on the aerosol particle light scattering coefficient (σsp is described in this study by comparing measurements from five European sites: the Jungfraujoch, located in the Swiss Alps at 3580 m a.s.l.; Ny-Ålesund, located on Spitsbergen in the Arctic; Mace Head, a coastal site in Ireland; Cabauw, a rural site in the Netherlands; and Melpitz, a regional background site in Eastern Germany. These sites were selected according to the aerosol type usually encountered at that location. The scattering enhancement factor f(RH, λ is the key parameter to describe the effect of water uptake on the particle light scattering. It is defined as the σsp(RH at a certain relative humidity (RH and wavelength λ divided by its dry value. f(RH at the five sites varied widely, starting at very low values of f(RH = 85%, λ = 550 nm around 1.28 for mineral dust, and reaching up to 3.41 for Arctic aerosol. Hysteresis behavior was observed at all sites except at the Jungfraujoch (due to the absence of sea salt. Closure studies and Mie simulations showed that both size and chemical composition determine the magnitude of f(RH. Both parameters are also needed to successfully predict f(RH. Finally, the measurement results were compared to the widely used aerosol model, OPAC (Hess et al., 1998. Significant discrepancies were seen, especially at intermediate RH ranges; these were mainly attributed to inappropriate implementation of hygroscopic growth in the OPAC model. Replacement of the hygroscopic growth with values from the recent literature resulted in a clear improvement of the OPAC model.

  2. Effect of Oblique Electromagnetic Ion Cyclotron Waves on Relativistic Electron Scattering: CRRES Based Calculation (United States)

    Gamayunov, K. V.; Khazanov, G. V.


    We consider the effect of oblique EMIC waves on relativistic electron scattering in the outer radiation belt using simultaneous observations of plasma and wave parameters from CRRES. The main findings can be s ummarized as follows: 1. In 1comparison with field-aligned waves, int ermediate and highly oblique distributions decrease the range of pitc h-angles subject to diffusion, and reduce the local scattering rate b y an order of magnitude at pitch-angles where the principle absolute value of n = 1 resonances operate. Oblique waves allow the absolute va lue of n > 1 resonances to operate, extending the range of local pitc h-angle diffusion down to the loss cone, and increasing the diffusion at lower pitch angles by orders of magnitude; 2. The local diffusion coefficients derived from CRRES data are qualitatively similar to the local results obtained for prescribed plasma/wave parameters. Conseq uently, it is likely that the bounce-averaged diffusion coefficients, if estimated from concurrent data, will exhibit the dependencies similar to those we found for model calculations; 3. In comparison with f ield-aligned waves, intermediate and highly oblique waves decrease th e bounce-averaged scattering rate near the edge of the equatorial lo ss cone by orders of magnitude if the electron energy does not excee d a threshold (approximately equal to 2 - 5 MeV) depending on specified plasma and/or wave parameters; 4. For greater electron energies_ ob lique waves operating the absolute value of n > 1 resonances are more effective and provide the same bounce_averaged diffusion rate near the loss cone as fiel_aligned waves do.

  3. Double parton scattering in the CGC: Double quark production and effects of quantum statistics (United States)

    Kovner, Alex; Rezaeian, Amir H.


    We consider forward inclusive production of two quarks in the high energy p-A collisions in the color-glass-condensate formalism. We demonstrate that the production cross section is determined by the convolution of the proton generalized double transverse momentum-dependent distribution functions with two independent eikonal scattering amplitudes: the product of two dipoles and a quadrupole. We explicitly demonstrate that the quadrupole amplitude term accounts for all the (initial and final state) effects of quantum statistics for identical fermions, and the correlations due to these effects. We also demonstrate that the effects due to quantum statistics (entirely encoded in the quadrupole) are parametrically leading contributions to the correlated particle production at large Nc. For nonidentical quarks the quadrupole term also leads to correlated production which (barring accidental cancellations) has characteristics similar to the Hanbury Brown-Twiss effect.

  4. Effects of random fields in an antiferromagnetic Ising bilayer film (United States)

    Kaneyoshi, T.


    The magnetic properties (phase diagrams and magnetizations) of an antiferromagnetic Ising bilayer film with random fields are investigated by the use of the effective field theory with correlations. It is examined how an uncompensated magnetization can be realized in the system, due to the effects of random fields in the two layers. They show the tricritical, compensation point and reentrant phenomena, depending on these parameters.

  5. Absence of skew scattering in two-dimensional systems: Testing the origins of the anomalous Hall effect


    Borunda, Mario F.; Nunner, Tamara S.; Luck, Thomas; Sinitsyn, N. A.; Timm, Carsten; Wunderlich, J.; Jungwirth, T.; Macdonald, A. H.; Sinova, Jairo


    We study the anomalous Hall conductivity in spin-polarized, asymmetrically confined two-dimensional electron and hole systems, focusing on skew-scattering contributions to the transport. We find that the skew scattering, principally responsible for the extrinsic contribution to the anomalous Hall effect, vanishes for the two-dimensional electron system if both chiral Rashba subbands are partially occupied, and vanishes always for the two-dimensional hole gas studied here, regardless of the ba...

  6. Experimental investigation of quantum effects in time-resolved resonance Rayleigh scattering from quantum well excitons

    DEFF Research Database (Denmark)

    Birkedal, Dan; Shah, Jagdeep; Shchegrov, Andrei V.


    Resonant Rayleigh scattering from quantum well excitons is investigated using ultrafast spectral interferometry. We isolate the coherent Rayleigh scattering from incoherent luminescence in a single speckle. Averaging the resonant Rayleigh intensity over several speckles allows us to identify...... features in support of quantum corrections to the classical description of the underlying scattering process....

  7. Size effects on the scattering matrices of clay particles: An experimental study

    Directory of Open Access Journals (Sweden)

    O. Munoz


    Full Text Available We present experimental scattering matrix elements as functions of the scattering angle of two sets of three samples of clays (yellow, green, and white. The measurements were performed in Amsterdam at a wavelength of 633 nm, and at the IAA cosmic dust laboratory in Granada at 647 nm. We study the impact of different sizes on the measured scattering matrix elements.

  8. Size effects on the scattering matrices of clay particles: an experimental study. (United States)

    Munoz, Olga; Moreno, F.; Dabrowska, D. D.; Volten, H.; Hovenier, J. W.


    We present experimental scattering matrix elements as functions of the scattering angle of two sets of three samples of clays (yellow, green and white). The measurements were performed in Amsterdam at 633 nm and at the IAA cosmic laboratory in Granada at 647 nm. We study the impact of different sizes on the measured scattering matrix elements.

  9. Skew scattering dominated anomalous Hall effect in Cox(MgO)100-x granular thin films

    KAUST Repository

    Zhang, Qiang


    We investigated the mechanism(s) of the anomalous Hall effect (AHE) in magnetic granular materials by fabricating 100-nm-thick thin films of Cox(MgO)100-x with a Co volume fraction of 34≤x≤100 using co-sputtering at room temperature. We measured the temperature dependence of longitudinal resistivity (ρxx) and anomalous Hall resistivity (ρAHE) from 5 K to 300 K in all samples. We found that when x decreases from 100 to 34, the values of ρxx and ρAHE respectively increased by about four and three orders in magnitude. By linearly fitting the data, obtained at 5 K, of anomalous Hall coefficient (Rs) and of ρxx to log(Rs)~γlog(ρxx), we found that our results perfectly fell on a straight line with a slope of γ= 0.97±0.02. This fitting value of γ in Rsρxxγ clearly suggests that skew scattering dominated the AHE in this granular system. To explore the effect of the scattering on the AHE, we performed the same measurements on annealed samples. We found that although both ρxx and ρAHE significantly reduced after annealing, the correlation between them was almost the same, which was confirmed by the fitted value, γ=0.99±0.03. These data strongly suggest that the AHE originates from the skew scattering in Co-MgO granular thin films no matter how strong the scatterings of electrons by the interfaces and defects is. This observation may be of importance to the development of spintronic devices based on MgO.

  10. Exploring halo effects in the scattering of $^{11}$Be on heavy targets at REX-ISOLDE

    CERN Multimedia


    We propose to measure the scattering of $^{11}$Be on heavy targets at energies around the Coulomb barrier with the aim to study the effect of the neutron halo on the reaction mechanisms. We expect to see deviations of the elastic cross sections with respect to Rutherford, even at energies below the barrier, due to the effect of dipole polarizability. We also expect to observe the inelastic excitation from the 1/2$^{+}$ ground state to the 1/2$^{-}$ excited state. One neutron transfer, as well as break-up cross sections will be obtained from the analysis of the $^{10}$Be fragments produced in the collision. We expect to obtain information on the B(E1) distribution in the low energy continuum of $^{11}$Be. \\\\ \\\\In a previous experiment, $^{11}$Be was produced and accelerated at REX-ISOLDE with an intensity of 10$^{5}$ pps. This beam intensity would allow us to measure the scattered fragments, at forward and backward angles, with a detector array based on silicon strip detectors. We ask for a total of 27 shift...

  11. Effective trapping of random walkers in complex networks. (United States)

    Hwang, S; Lee, D-S; Kahng, B


    Exploring the World Wide Web has become one of the key issues in information science, specifically in view of its application to the PageRank-like algorithms used in search engines. The random walk approach has been employed to study such a problem. The probability of return to the origin (RTO) of random walks is inversely related to how information can be accessed during random surfing. We find analytically that the RTO probability for a given starting node shows a crossover from a slow to a fast decay behavior with time and the crossover time increases with the degree of the starting node. We remark that the RTO probability becomes almost constant in the early-time regime as the degree exponent approaches two. This result indicates that a random surfer can be effectively trapped at the hub and supports the necessity of the random jump strategy empirically used in the Google's search engine.

  12. Exchange nonlocal effects in the nuclear heavy-ion elastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, M.A.C.; Chamon, L.C.; Pereira, D. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Galetti, D. [Instituto de Fisica Teorica (IFT), Sao Paulo, SP (Brazil)


    An interesting feature of the presence of exchange nonlocal effects in the nucleus-nucleus collision description in the modification of the nuclear barrier. This results, on the one hand, in an enhancement of the nuclear fusion cross sections due to the modification introduced in the basic quantum mechanical tunnelling calculation and, on the other hand, leads one to the study of the consequences of those effects in the nuclear elastic scattering. In this paper, we discuss the manifestations of the presence of those effects through an approximated model Schroedinger equation describing a nuclear system colliding at energies around the barrier. An an application, the elastic channel and, concomitantly, the fusion processes are studied for the {sup 16} O + {sup 60} Ni system at energies close to the barrier. (author). 15 refs., 4 figs.

  13. The mathematical model reduces the effect of distance to the scatter images gray level (United States)

    Sun, Li-na


    In x-ray scanning system, scatter images are obtained to provide information on material density. The forward and backward scatter is related to solid angle. Scatter is therefore dependent on the distance of the scanned object from the x-ray source. In the real world, an object may be placed anywhere on the conveyer belt, so the measured intensity will contain errors relative to the ideal intensity. This makes classification results less reliable. Extraction of characteristic values L associated with the density; need to know the gray levels of scatter images, so how to base on forward scatter and back scatter images to determine the scatter image gray level is first necessary to solve the problem. The author combined with the forward scatter and backscatter images,then established higher order gray-level mathematical model of scattering images, to eliminate the impact of distance on the scatter images, to obtain more accurate gray level of scatter image. Then compare the error use of LMS algorithm and the LS algorithm to solving mathematical model parameters, LS algorithm ultimately prove less error and experimental validation of the superiority of the LS algorithm.

  14. First Search for the EMC Effect and Nuclear Shadowing in Neutrino Nucleus Deep Inelastic Scattering at MINERvA

    Energy Technology Data Exchange (ETDEWEB)

    Mousseau, Joel A. [Univ. of Florida, Gainesville, FL (United States)


    Decades of research in electron-nucleus deep inelastic scattering (DIS) have provided a clear picture of nuclear physics at high momentum transfer. While these effects have been clearly demonstrated by experiment, the theoretical explanation of their origin in some kinematic regions has been lacking. Particularly, the effects in the intermediate regions of Bjorken-x, anti-shadowing and the EMC effect have no universally accepted quantum mechanical explanation. In addition, these effects have not been measured systematically with neutrino-nucleus deep inelastic scattering, due to experiments lacking multiple heavy targets.

  15. Effects of Fat and Protein Levels on Foraging Preferences of Tannin in Scatter-Hoarding Rodents (United States)

    Wang, Bo; Chen, Jin


    Both as consumers and dispersers of seeds, scatter-hoarding rodents often play an important role in the reproductive ecology of many plant species. However, the seeds of many plant species contain tannins, which are a diverse group of water-soluble phenolic compounds that have a high affinity for proteins. The amount of tannins in seeds is expected to affect rodent foraging preferences because of their major impact on rodent physiology and survival. However, variable results have been obtained in studies that evaluated the effects of tannin on rodent foraging behavior. Hence, in this study, we aimed to explain these inconsistent results and proposed that a combination of seed traits might be important in rodent foraging behavior, because it is difficult to distinguish between the effects of individual traits on rodent foraging behavior and the interactions among them. By using a novel artificial seed system, we manipulated seed tannin and fat/protein levels to examine directly the univariate effects of each component on the seed preferences of free-ranging forest rats (Apodemus latronum and Apodemus chevrieri) during the behavioral process of scatter hoarding. Our results showed that both tannin and fat/protein had significant effects on rodent foraging behavior. Although only a few interactive effects of tannin and fat/protein were recorded, higher concentrations of both fat and protein could attenuate the exclusion of seeds with higher tannin concentrations by rodents, thus influencing seed fate. Furthermore, aside from the concentrations of tannin, fat, and protein, numerous other traits of plant seeds may also influence rodent foraging behavior. We suggest that by clarifying rodent foraging preferences, a better understanding of the evolution of plant seed traits may be obtained because of their strong potential for selective pressure. PMID:22808217

  16. The Effect of Nuclear Elastic Scattering on Temperature Equilibration Rate of Ions in Fusion Plasma

    Directory of Open Access Journals (Sweden)

    M. Mahdavi


    Full Text Available A plasma with two different particle types and at different temperatures has been considered, so that each type of ion with Maxwell-Boltzmann distribution function is in temperature equilibrium with itself. Using the extracted nuclear elastic scattering differential cross-section from experimental data, solving the Boltzmann equation, and also taking into account the mobility of the background particles, temperature equilibration rate between two different ions in a fusion plasma is calculated. The results show that, at higher temperature differences, effect of nuclear elastic scattering is more important in calculating the temperature equilibration rate. The obtained expressions have general form so that they are applicable to each type of particle for background (b and each type for projectile (p. In this paper, for example, an equimolar Deuterium-Hydrogen plasma with density n=5×1025 cm−3 is chosen in which the deuteron is the background particle with temperature (also electron temperature Tb=1 keV (usual conditions for a fusion plasma at the ignition instant and the proton is the projectile with temperature Tp>Tb. These calculations, particularly, are very important for ion fast ignition in inertial confinement fusion concept.

  17. Balancing Near-Field Enhancement, Absorption, and Scattering for Effective Antenna-Reactor Plasmonic Photocatalysis. (United States)

    Li, Kun; Hogan, Nathaniel J; Kale, Matthew J; Halas, Naomi J; Nordlander, Peter; Christopher, Phillip


    Efficient photocatalysis requires multifunctional materials that absorb photons and generate energetic charge carriers at catalytic active sites to facilitate a desired chemical reaction. Antenna-reactor complexes are an emerging multifunctional photocatalytic structure where the strong, localized near field of the plasmonic metal nanoparticle (e.g., Ag) is coupled to the catalytic properties of the nonplasmonic metal nanoparticle (e.g., Pt) to enable chemical transformations. With an eye toward sustainable solar driven photocatalysis, we investigate how the structure of antenna-reactor complexes governs their photocatalytic activity in the light-limited regime, where all photons need to be effectively utilized. By synthesizing core@shell/satellite (Ag@SiO 2 /Pt) antenna-reactor complexes with varying Ag nanoparticle diameters and performing photocatalytic CO oxidation, we observed plasmon-enhanced photocatalysis only for antenna-reactor complexes with antenna components of intermediate sizes (25 and 50 nm). Optimal photocatalytic performance was shown to be determined by a balance between maximized local field enhancements at the catalytically active Pt surface, minimized collective scattering of photons out of the catalyst bed by the complexes, and minimal light absorption in the Ag nanoparticle antenna. These results elucidate the critical aspects of local field enhancement, light scattering, and absorption in plasmonic photocatalyst design, especially under light-limited illumination conditions.

  18. Dimensional scale effects on surface enhanced Raman scattering efficiency of self-assembled silver nanoparticle clusters

    Energy Technology Data Exchange (ETDEWEB)

    Fasolato, C. [Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy); Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia, V.le Regina Elena, 291, 00185 Rome (Italy); Domenici, F., E-mail:, E-mail:; De Angelis, L.; Luongo, F.; Postorino, P., E-mail:, E-mail: [Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy); Sennato, S. [Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy); CNR-IPCS UOS Roma, Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy); Mura, F. [Dip. Scienze di Base Applicate all' Ingegneria, Università Sapienza, Via A. Scarpa, 16, 00185 Rome (Italy); Costantini, F. [Dip. Ingegneria Astronautica Elettrica ed Energetica, Università Sapienza, Via Eudossiana, 18, 00184 Rome (Italy); Bordi, F. [Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy); Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia, V.le Regina Elena, 291, 00185 Rome (Italy); CNR-IPCS UOS Roma, Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy)


    A study of the Surface Enhanced Raman Scattering (SERS) from micrometric metallic nanoparticle aggregates is presented. The sample is obtained from the self-assembly on glass slides of micro-clusters of silver nanoparticles (60 and 100 nm diameter), functionalized with the organic molecule 4-aminothiophenol in water solution. For nanoparticle clusters at the micron scale, a maximum enhancement factor of 10{sup 9} is estimated from the SERS over the Raman intensity ratio normalized to the single molecule contribution. Atomic force microscopy, correlated to spatially resolved Raman measurements, allows highlighting the connection between morphology and efficiency of the plasmonic system. The correlation between geometric features and SERS response of the metallic structures reveals a linear trend of the cluster maximum scattered intensity as a function of the surface area of the aggregate. On given clusters, the intensity turns out to be also influenced by the number of stacking planes of the aggregate, thus suggesting a plasmonic waveguide effect. The linear dependence results weakened for the largest area clusters, suggesting 30 μm{sup 2} as the upper limit for exploiting the coherence over large scale of the plasmonic response.

  19. Effect of uniaxial strain on the optical Drude scattering in graphene (United States)

    Chhikara, Manisha; Gaponenko, Iaroslav; Paruch, Patrycja; Kuzmenko, Alexey B.


    Graphene is a mechanically robust 2D material promising for flexible optoelectronic applications. However, its electromagnetic properties under strain are experimentally poorly understood. Here we present the far-infrared transmission spectra of large-area chemical-vapor deposited monolayer graphene on a polyethylene terephthalate substrate subjected to uniaxial strain. The effective strain value is calibrated using the Raman spectroscopy and corrected for a relaxation of wrinkles and folds seen directly by atomic-force microscopy. We find that while the Drude weight and the Fermi level remain constant, the scattering rate increases by more than 10% per 1% of applied strain, showing a high level of reproducibility during strain cycling. As a result, the electronic mobility and optical absorption of graphene at terahertz and lower frequencies appear to also be sensitive to strain, which opens pathways to control these key parameters mechanically. We suggest that such a functionality can be potentially used in flexible optoelectronic and microelectromechanical systems based on graphene. By combining our findings with existing theoretical models, we discuss the possible mechanisms of strain-controlled Drude scattering.

  20. Effects of tissue fixation on coherent anti-Stokes Raman scattering images of brain (United States)

    Galli, Roberta; Uckermann, Ortrud; Koch, Edmund; Schackert, Gabriele; Kirsch, Matthias; Steiner, Gerald


    Coherent anti-Stokes Raman scattering (CARS) microscopy is an emerging multiphoton technique for the label-free histopathology of the central nervous system, by imaging the lipid content within the tissue. In order to apply the technique on standard histology sections, it is important to know the effects of tissue fixation on the CARS image. Here, we report the effects of two common fixation methods, namely with formalin and methanol-acetone, on mouse brain and human glioblastoma tissue. The variations induced by fixation on the CARS contrast and intensity were compared and interpreted using Raman microspectroscopy. The results show that, whenever unfixed cryosections cannot be used, fixation with formalin constitutes an alternative which does not deteriorate substantially the contrast generated by the different brain structures in the CARS image. Fixation with methanol-acetone strongly modifies the tissue lipid content and is therefore incompatible with the CARS imaging.

  1. Laser light-scattering study of the toxic effects of methylmercury on sperm motility

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, M.K.; Lee, W.I.; Mottet, N.K.; Burbacher, T.M.


    An in vitro study was designed using the laser light-scattering technique to obtain further information on the dose-effect relationship of methylmercury on sperm motility. The technique provided a quantitative evaluation of sperm swimming speed. Semen samples were collected from normal male Macaca fascicularis monkeys by anal electroejaculation. Methylmercury was added to aliquots of sperm suspensions in BWW medium in doses of 10, 5, 2, and 1 ppm. After 3 hours, the relative speed was 35%, 59%, 69%, and 92% of the corresponding controls at doses of 10, 5, 2, and 1 ppm, respectively. The percentage of motile spermatozoa decreased significantly at 10 ppm. By microscopic observation abnormal motility was detected at 5 and 10 ppm, especially after 20 to 40 minutes. Head movement increased from side to side, and many spermatozoa developed coiled tails. The technique proved useful for defining the dose-effect relationship of methylmercury and sperm swimming speed.

  2. Implementing nursing diagnostics effectively: cluster randomized trial.

    NARCIS (Netherlands)

    Müller-Staub, M.; Needham, I.; Odenbreit, M.; Lavin, M.A.; Achterberg, T. van


    AIM: This paper is a report of a study to investigate the effect of guided clinical reasoning. This method was chosen as a follow-up educational measure (refresher) after initial implementation of standardized language. BACKGROUND: Research has demonstrated nurses' need for education in diagnostic

  3. Random Effects Structure for Confirmatory Hypothesis Testing: Keep It Maximal (United States)

    Barr, Dale J.; Levy, Roger; Scheepers, Christoph; Tily, Harry J.


    Linear mixed-effects models (LMEMs) have become increasingly prominent in psycholinguistics and related areas. However, many researchers do not seem to appreciate how random effects structures affect the generalizability of an analysis. Here, we argue that researchers using LMEMs for confirmatory hypothesis testing should minimally adhere to the…

  4. The effect of electron scattering from disordered grain boundaries on the resistivity of metallic nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Arenas, Claudio [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Blanco Encalada 2008, Casilla 487-3, Santiago 8370449 (Chile); Synopsys Inc., Avenida Vitacura 5250, Oficina 708, Vitacura, Santiago (Chile); Henriquez, Ricardo [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Casilla 110-V, Valparaíso (Chile); Moraga, Luis [Universidad Central de Chile, Toesca 1783, Santiago (Chile); Muñoz, Enrique [Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 7820436 (Chile); Munoz, Raul C., E-mail: [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Blanco Encalada 2008, Casilla 487-3, Santiago 8370449 (Chile)


    Highlights: • Quantum theory of the resistivity arising from electron-grain boundary scattering in nanometric metallic structures. • The resistivity is controlled by the collective properties of the grain assembly, by the allowed Kronig-Penney (KP) bands and by the electron transmission probability across successive grains. • When the grain diameter d is larger than the electron mean free path l, the increase in resistivity arises mainly from a decrease of the number of states at the Fermi surface that are allowed KP bands. • When the grain diameter d is smaller than the electron mean free path l, the increase in resistivity arises primarily from Anderson localization caused by electron transmission across successive grains. - Abstract: We calculate the electrical resistivity of a metallic specimen, under the combined effects of electron scattering by impurities, grain boundaries, and rough surfaces limiting the film, using a quantum theory based upon the Kubo formalism. Grain boundaries are represented by a one-dimensional periodic array of Dirac delta functions separated by a distance “d” giving rise to a Kronig–Penney (KP) potential. We use the Green's function built from the wave functions that are solutions of this KP potential; disorder is included by incorporating into the theory the probability that an electron is transmitted through several successive grain boundaries. We apply this new theory to analyze the resistivity of samples S1, S2, S7 and S8 measured between 4 and 300 K reported in Appl. Surf. Science273, 315 (2013). Although both the classical and the quantum theories predict a resistivity that agrees with experimental data to within a few percent or better, the phenomena giving rise to the increase of resistivity over the bulk are remarkably different. Classically, each grain boundary contributes to the electrical resistance by reflecting a certain fraction of the incoming electrons. In the quantum description, there are states

  5. Magnetic effects on the resonant inelastic soft X-ray scattering in the transition metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Grebennikov, V.I. E-mail:


    Applications of resonant inelastic soft X-ray scattering for studying magnetic systems are discussed. The emission spectra show the magnetic circular dichroism when they are excited by the polarized incident X-ray radiation. A theoretical description for L{alpha} and L{beta} emission spectra recorded at different excitation photon energies gives the main spectral lines: a normal emission peak, with the constant energy, and a quasi-elastic peak that moves in energy scale when the incident photon energy changes. The intensity of the quasi-elastic peak is strongly controlled by valence electron excitations due to core-hole effects. The emission experiments contain information on the atomic magnetic moment values in the case of depolarized incident radiation and in disordered magnetic states. The integral intensities ratio for L{beta}/L{alpha} lines in transition metal oxides are analyzed from this point of view.

  6. Effects of modulated pulse format on spontaneous Brillouin scattering spectrum and BOTDR sensing system (United States)

    Hao, Yunqi; Ye, Qing; Pan, Zhengqing; Cai, Haiwen; Qu, Ronghui; Yang, Zhongmin


    The signal noise ratio (SNR) enhancement effects of spontaneous Brillouin scattering spectrum on Brilloluin optical time domain reflectometry (BOTDR) sensing system have been analyzed theoretically and demonstrated experimentally through changing the modulated pulse format. With the same pulse width or same spatial resolution, the SNR is larger for triangular pulse. Take the width of 200 ns as an illustration, the SNRs of the coherent detection power spectrum for trapezoidal pulse and triangular pulse increase 3 dB and 4.8 dB relative to that of rectangular pulse respectively. The corresponding spectral linewidthes are narrowed and the sensing distances are also increased by about two times from the rectangular pulse to the triangular pulse. This phenomenon will be helpful to improve the spatial resolution or achieve longer sensing distance in the BOTDR sensing system at the same systemic conditions.

  7. Effect of crystalline family and orientation on stimulated Brillouin scattering in whispering-gallery mode resonators. (United States)

    Diallo, Souleymane; Aubry, Jean-Pierre; Chembo, Yanne K


    Ultra-high Q whispering-gallery mode resonators pumped by a continuous-wave laser are known to enhance stimulated Brillouin scattering when optimal resonance and phase-matching conditions are met. In crystalline resonators, this process depends critically on the crystal orientation and family, which impose the elastic constants defining the velocity of the acoustic waves. In this article, we investigate the effect of crystalline orientation and family on this velocity which is proportional to the Brillouin frequency down-shift. In particular, the study is based on the development of a model and numerical simulations of acoustic wave velocities that propagate along the periphery of four fluoride crystals, namely calcium, magnesium, lithium and barium fluoride. We find that depending on the crystal and its orientation, the frequency excursion around the Brillouin offset can vary from few tens of kHz to more than a GHz.

  8. Effects on measurement of photon-atom scattering of applied pressures on sample at different thickness

    Energy Technology Data Exchange (ETDEWEB)

    Icelli, Orhan [Department of Physics Education, Education Faculty of Erzincan, Atatuerk University, Erzincan (Turkey)]. E-mail:; Erzeneoglu, Salih [Department of Physics, Faculty of Sciences, Atatuerk University, Erzurum (Turkey)


    N{sub coh}/N{sub Comp} and NK{sub {beta}}/NK{sub {alpha}} intensity ratios of scattered photons by Zn in the linear region and the infinite mass thickness region are measured as functions of the pressure used for compressing the pellets with a Si(Li) detector using Am-241 and Fe-55 annular source. Besides, the effect on the experimental intensity ratio of relation between two different thicknesses of sample with applied different pressures on the sample is investigated in this study. Harmony between the linear and infinitive (critical) thickness region and the applied pressure on the sample has directly affected the experimental intensity ratios. Experimental results were not compared with various theoretical values in the literature, for present results constitute the first experimental measurements.

  9. Effects of nonlinear phase modulation on Bragg scattering in the low-conversion regime

    DEFF Research Database (Denmark)

    Andersen, Lasse Mejling; Cargill, D. S.; McKinstrie, C. J.


    In this paper, we consider the effects of nonlinear phase modulation on frequency conversion by four-wave mixing (Bragg scattering) in the low-conversion regime. We derive the Green functions for this process using the time-domain collision method, for partial collisions, in which the four fields...... interact at the beginning or the end of the fiber, and complete collisions, in which the four fields interact at the midpoint of the fiber. If the Green function is separable, there is only one output Schmidt mode, which is free from temporal entanglement. We find that nonlinear phase modulation always...... chirps the input and output Schmidt modes and renders the Green function formally nonseparable. However, by pre-chirping the pumps, one can reduce the chirps of the Schmidt modes and enable approximate separability. Thus, even in the presence of nonlinear phase modulation, frequency conversion...

  10. Memory-effect based deconvolution microscopy for super-resolution imaging through scattering media (United States)

    Edrei, Eitan; Scarcelli, Giuliano


    High-resolution imaging through turbid media is a fundamental challenge of optical sciences that has attracted a lot of attention in recent years for its wide range of potential applications. Here, we demonstrate that the resolution of imaging systems looking behind a highly scattering medium can be improved below the diffraction-limit. To achieve this, we demonstrate a novel microscopy technique enabled by the optical memory effect that uses a deconvolution image processing and thus it does not require iterative focusing, scanning or phase retrieval procedures. We show that this newly established ability of direct imaging through turbid media provides fundamental and practical advantages such as three-dimensional refocusing and unambiguous object reconstruction.

  11. Transverse spin effects in hadron-pair production from semi-inclusive deep inelastic scattering

    CERN Document Server

    Adolph, C.; Alexakhin, V.Yu.; Alexeev, G.D.; Amoroso, A.; Antonov, A.A.; Badelek, B.; Balestra, F.; Barth, J.; Baum, G.; Bedfer, Y.; Bernhard, J.; Bertini, R.; Bettinelli, M.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Bordalo, P.; Bradamante, F.; Braun, C.; Bravar, A.; Bressan, A.; Burtin, E.; Chaberny, D.; Chiosso, M.; Chung, S.U.; Cicuttin, A.; Crespo, M.L.; Dalla Torre, S.; Das, S.; Dasgupta, S.S.; Dhara, L.; Donskov, S.V.; Duic, V.; Dunnweber, W.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P.D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Filin, A.; Finger, M.; jr., M.Finger; Fischer, H.; Franco, C.; Friedrich, J.M.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O.P.; Gazda, R.; Geyer, R.; Giorgi, M.; Gnesi, I.; Gobbo, B.; Grabmuller, S.; Grasso, A.; Grube, B.; Gushterski, R.; Guskov, A.; Guthorl, T.; Haas, F.; von Harrach, D.; Heinsius, F.H.; Herrmann, F.; Hess, C.; Hinterberger, F.; Horikawa, N.; Hoppner, Ch.; d'Hose, N.; Huber, S.; Ishimoto, S.; Ivanov, O.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jasinski, P.; Joosten, R.; Kabuss, E.; Kang, D.; Ketzer, B.; Khaustov, G.V.; Khokhlov, Yu.A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koblitz, S.; Koivuniemi, J.H.; Kolosov, V.N.; Konigsmann, K.; Konstantinov, V.F.; Korzenev, A.; Kotzinian, A.M.; Kramer, M.; Kroumchtein, Z.V.; Kunne, F.; Kurek, K.; Lauser, L.; Lednev, A.A.; Lehmann, A.; Levorato, S.; Lichtenstadt, J.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G.K.; Mann, A.; Marchand, C.; Martin, A.; Marzec, J.; Massmann, F.; Matsuda, T.; Meyer, W.; Michigami, T.; Mikhailov, Yu.V.; Moinester, M.A.; Morreale, A.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V.I.; Nowak, W.D.; Nunes, A.S.; Olshevsky, A.G.; Ostrick, M.; Padee, A.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Perevalova, E.; Pesaro, G.; Peshekhonov, D.V.; Piragino, G.; Platchkov, S.; Pochodzalla, J.; Polyakov, V.A.; Pontecorvo, G.; Pretz, J.; Quaresma, M.; Quintans, C.; Rajotte, J.F.; Ramos, S.; Rapatsky, V.; Reicherz, G.; Richter, A.; Rondio, E.; Rossiyskaya, N.S.; Ryabchikov, D.I.; Samoylenko, V.D.; Sandacz, A.; Sapozhnikov, M.G.; Sarkar, S.; Savin, I.A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schluter, T.; Schmidt, K.; Schmitt, L.; Schonning, K.; Schopferer, S.; Schott, M.; Shevchenko, O.Yu.; Silva, L.; Sinha, L.; Slunecka, M.; Smirnov, G.I.; Sosio, S.; Sozzi, F.; Srnka, A.; Stolarski, M.; Sulc, M.; Sulej, R.; Sznajder, P.; Takekawa, S.; Wolbeek, J.Ter; Tessaro, S.; Tessarotto, F.; Teufel, A.; Tkatchev, L.G.; Uhl, S.; Uman, I.; Vandenbroucke, M.; Virius, M.; Vlassov, N.V.; Vossen, A.; Wang, L.; Windmolders, R.; Wislicki, W.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zhuravlev, N.; Zvyagin, A.


    First measurements of azimuthal asymmetries in hadron-pair production in deep-inelastic scattering of muons on transversely polarised ^6LiD (deuteron) and NH_3 (proton) targets are presented. The data were taken in the years 2002-2004 and 2007 with the COMPASS spectrometer using a muon beam of 160 GeV/c at the CERN SPS. The asymmetries provide access to the transversity distribution functions, without involving the Collins effect as in single hadron production. The sizeable asymmetries measured on the NH_ target indicate non-vanishing u-quark transversity and two-hadron interference fragmentation functions. The small asymmetries measured on the ^6LiD target can be interpreted as indication for a cancellation of u- and d-quark transversities.

  12. Scattering of gravitational radiation - Second order moments of the wave amplitude

    NARCIS (Netherlands)

    Macquart, JP

    Gravitational radiation that propagates through an inhomogeneous mass distribution is subject to random gravitational tensing, or scattering, causing variations in the wave amplitude and temporal smearing of the signal. A statistical theory is constructed to treat these effects. The statistical


    Directory of Open Access Journals (Sweden)

    Anna eKovalchuk


    Full Text Available Irradiated cells can signal damage and distress to both close and distant neighbors that have not been directly exposed to the radiation (naïve bystanders. While studies have shown that such bystander effects occur in the shielded brain of animals upon body irradiation, their mechanism remains unexplored. Observed effects may be caused by some blood-borne factors; however they may also be explained, at least in part, by very small direct doses received by the brain that result from scatter or leakage. In order to establish the roles of low doses of scatter irradiation in the brain response, we developed a new model for scatter irradiation analysis whereby one rat was irradiated directly at the liver and the second rat was placed adjacent to the first and received a scatter dose to its body and brain. This work focuses specifically on the response of the latter rat brain to the low scatter irradiation dose. Here, we provide the first experimental evidence that very low, clinically relevant doses of scatter irradiation alter gene expression, induce changes in dendritic morphology, and lead to behavioral deficits in exposed animals. The results showed that exposure to radiation doses as low as 0.115 cGy caused changes in gene expression and reduced spine density, dendritic complexity, and dendritic length in the prefrontal cortex tissues of females, but not males. In the hippocampus, radiation altered neuroanatomical organization in males, but not in females. Moreover, low dose radiation caused behavioral deficits in the exposed animals. This is the first study to show that low dose scatter irradiation influences the brain and behavior in a sex-specific way.

  14. The blocked-random effect in pictures and words. (United States)

    Toglia, M P; Hinman, P J; Dayton, B S; Catalano, J F


    Picture and word recall was examined in conjunction with list organization. 60 subjects studied a list of 30 items, either words or their pictorial equivalents. The 30 words/pictures, members of five conceptual categories, each represented by six exemplars, were presented either blocked by category or in a random order. While pictures were recalled better than words and a standard blocked-random effect was observed, the interaction indicated that the recall advantage of a blocked presentation was restricted to the word lists. A similar pattern emerged for clustering. These findings are discussed in terms of limitations upon the pictorial superiority effect.

  15. The effect of scattering on sound field control with a circular double-layer array of loudspeakers

    DEFF Research Database (Denmark)

    Chang, Jiho; Jacobsen, Finn


    A recent study has shown that a circular double-layer array of loudspeakers makes it possible to achieve a sound field control that can generate a controlled field inside the array and reduce sound waves propagating outside the array. This is useful if it is desirable not to disturb people outside...... the array or to prevent the effect of reflections from the room. The study assumed free field condition, however in practice a listener will be located inside the array. The listener scatters sound waves, which propagate outward. Consequently, the scattering effect can be expected to degrade the performance...

  16. A new SERS: scattering enhanced Raman scattering (United States)

    Bixler, Joel N.; Yakovlev, Vladislav V.


    Raman spectroscopy is a powerful technique that can be used to obtain detailed chemical information about a system without the need for chemical markers. It has been widely used for a variety of applications such as cancer diagnosis and material characterization. However, Raman scattering is a highly inefficient process, where only one in 1011 scattered photons carry the needed information. Several methods have been developed to enhance this inherently weak effect, including surface enhanced Raman scattering and coherent anti-Stokes Raman scattering. These techniques suffer from drawbacks limiting their commercial use, such as the need for spatial localization of target molecules to a `hot spot', or the need for complex laser systems. Here, we present a simple instrument to enhance spontaneous Raman scattering using elastic light scattering. Elastic scattering is used to substantially increase the interaction volume. Provided that the scattering medium exhibits very low absorption in the spectral range of interest, a large enhancement factor can be attained in a simple and inexpensive setting. In our experiments, we demonstrate an enhancement of 107 in Raman signal intensity. The proposed novel device is equally applicable for analyzing solids, liquids, and gases.

  17. Bio-inspired, colorful, flexible, defrostable light-scattering hybrid films for the effective distribution of LED light. (United States)

    An, Seongpil; Jo, Hong Seok; Kim, Yong Il; Song, Kyo Yong; Kim, Min-Woo; Lee, Kyu Bum; Yarin, Alexander L; Yoon, Sam S


    Bioluminescent jellyfish has a unique structure derived from fiber/polymer interfaces that is advantageous for effective light scattering in the dark, deep sea water. Herein, we demonstrate the fabrication of bio-inspired hybrid films by mimicry of the jellyfish's structure, leading to excellent light-scattering performance and defrosting capability. A haze value reaching 59.3% and a heating temperature of up to 292 °C were achieved with the films. Accordingly, the developed surface constitutes an attractive optical device for lighting applications, especially for street or vehicle luminaries for freezing Arctic-climate countries. The morphological details of the hybrid films were revealed by scanning electron microscopy. The light-scattering properties of these films were examined by ultraviolet-visible-infrared spectrophotometry and anti-glare effect analyses. The defrosting performance of the hybrid films was evaluated via heating tests and infra-red observations.

  18. Forward scatter dose effect at metallic interfaces irradiated by X and gamma ray therapy beams

    Energy Technology Data Exchange (ETDEWEB)

    Ravikumar, M.; Ravichandran, R.; Supe, S.S. [Kidwai Memorial Inst. of Oncology, Bangalore (India). Dept. of Radiation Physics


    Aim: In this study forward scattering effects near different metallic interfaces are measured for Co-60 gamma and 6 and 18 MV photon beams. The studied effects are the transport of secondary electrons across the metallic interface and the scattering of photons by the metallic inhomogeneity. Materials and Methods: All measurements were carried out with a PTW thin-window, parallel plate ionisation chamber (B 23344-036) and an RDM-1F electrometer with digital readout. Thin sheets of aluminium, mild steel, copper, cadmium and lead were used as inhomogeneities. The inhomogeneities were placed between the polystyrene phantom and the front window of the chamber which was maintained at 100 cm SSD. Results: It was noticed that for a high energy photon beam (18 MV) the forward scatter dose factor (FSDF) increases rapidly as the thickness of the metallic inhomogeneity increases. For low energy photons, there is a sharp initial decrease of the FSDF until a minimum value is reached followed by a slow increase with increasing thickness of the inhomogeneity. It was also noted that the FSDF variation at off-axis distances has slightly more slope compared with the ionization ratio (IR) curves for both 6 MV and 18 MV photons. However, the variation in slope is prominent for 18 MV compared with 6 MV photon beam. Conclusion: The sharp dose decrease observed downstream of a metallic inhomogeneity at relatively low photon energies (Co-60, 6 MV) is attributed to the internal scattering of secondary electrons within the metal. The dose enhancement observed for high energy photon beams is attributed to the domination of the pair production process, increasing with atomic number. Since FSDF is dependent on the photon beam spectra, it can be used as a measure of beam quality across the beam. (orig.) [German] Ziel: Messung der Vorwaertsstreueffekte von Co-60-Gamma- sowie 6- und 18-MV-Photonenstrahlen in der Umgebung unterschiedlicher Metallgrenzflaechen. Untersuchung des Transports von

  19. Scattering of Skyrmions

    Directory of Open Access Journals (Sweden)

    David Foster


    Full Text Available In this paper, we present a detailed study of Skyrmion–Skyrmion scattering for two B=1 Skyrmions in the attractive channel where we observe two different scattering regimes. For large separation, the scattering can be approximated as interacting dipoles. We give a qualitative estimate when this approximation breaks down. For small separations we observe an additional short-range repulsion which is qualitatively similar to monopole scattering. We also observe the interesting effect of “rotation without rotating” whereby two Skyrmions, whose orientations remain constant while well-separated, change their orientation after scattering. We can explain this effect by following preimages through the scattering process, thereby measuring which part of an in-coming Skyrmion forms part of an out-going Skyrmion. This leads to a new way of visualising Skyrmions. Furthermore, we consider spinning Skyrmions and find interesting trajectories.

  20. Effect of extended strain fields on point defect phonon scattering in thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, Brenden R.; Peng, Haowei; Lopez, Armando; Parilla, Philip A.; Lany, Stephan; Toberer, Eric S.


    The design of thermoelectric materials often involves the integration of point defects (alloying) as a route to reduce the lattice thermal conductivity. Classically, the point defect scattering strength follows from simple considerations such as mass contrast and the presence of induced strain fields (e.g. radius contrast, coordination changes). While the mass contrast can be easily calculated, the associated strain fields induced by defect chemistry are not readily predicted and are poorly understood. In this work, we use classical and first principles calculations to provide insight into the strain field component of phonon scattering from isoelectronic point defects. Our results also integrate experimental measurements on bulk samples of SnSe and associated alloys with S, Te, Ge, Sr and Ba. These efforts highlight that the strength and extent of the resulting strain field depends strongly on defect chemistry. Strain fields can have a profound impact on the local structure. For example, in alloys containing Ba, the strain fields have significant spatial extent (1 nm in diameter) and produce large shifts in the atomic equilibrium positions (up to 0.5 A). Such chemical complexity suggests that computational assessment of point defects for thermal conductivity depression should be hindered. However, in this work, we present and verify several computational descriptors that correlate well with the experimentally measured strain fields. Furthermore, these descriptors are conceptually transparent and computationally inexpensive, allowing computation to provide a pivotal role in the screening of effective alloys. The further development of point defect engineering could complement or replace nanostructuring when optimizing the thermal conductivity, offering the benefits of thermodynamic stability, and providing more clearly defined defect chemistry.

  1. Gravitational scattering, post-Minkowskian approximation and Effective One-Body theory

    CERN Document Server

    Damour, Thibault


    A novel approach to the Effective One-Body description of gravitationally interacting two-body systems is introduced. This approach is based on the post-Minkowskian approximation scheme (perturbation theory in G, without assuming small velocities), and employs a new dictionary focussing on the functional dependence of the scattering angle on the total energy and the total angular momentum of the system. Using this approach, we prove to all orders in v/c two results that were previously known to hold only to a limited post-Newtonian accuracy: (i) the relativistic gravitational dynamics of a two-body system is equivalent, at first post-Minkowskian order, to the relativistic dynamics of an effective test particle moving in a Schwarzschild metric; and (ii) this equivalence requires the existence of an exactly quadratic map between the real (relativistic) two-body energy and the (relativistic) energy of the effective particle. The same energy map is also shown to apply to the effective one-body description of two ...

  2. The energy loss and nuclear absorption effects in semi-inclusive deep inelastic scattering on nucleus (United States)

    Song, Li-Hua; Xin, Shang-Fei; Liu, Na


    Semi-inclusive deep inelastic lepton-nucleus scattering provides a good opportunity to investigate the cold nuclear effects on quark propagation and hadronization. Considering the nuclear modification of the quark energy loss and nuclear absorption effects in final state, the leading-order computations on hadron multiplicity ratios for both hadronization occurring outside and inside the medium are performed with the nuclear geometry effect of the path length L of the struck quark in the medium. By fitting the HERMES two-dimensional data on the multiplicity ratios for positively and negatively charged pions and kaons produced on neon, the hadron–nucleon inelastic cross section {σ }h for different identified hadrons is determined, respectively. It is found that our predictions obtained with the analytic parameterizations of quenching weights based on BDMPS formalism and the nuclear absorption factor {N}A(z,ν ) are in good agreement with the experimental measurements. This indicates that the energy loss and nuclear absorption are the main nuclear effects inducing a reduction of the hadron yield for quark hadronization occurring outside and inside the nucleus, respectively.

  3. Investigations of scattering and field enhancement effects in retardation-based plasmonic nanoantennas

    DEFF Research Database (Denmark)

    Nielsen, M. G.; Pors, A.; Nielsen, Rasmus Bundgaard


    interfering short-range surface plasmon polaritons (SR-SPP) and that the transformation of straight nanorods into split-rings by bending significantly influences the scattering strength. Importantly, strong suppression of scattering for the fundamental SR-SPP mode is observed when the bend radius is decreased...

  4. Effects of Raman scattering in quantum state-preserving frequency conversion

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Andersen, Lasse Mejling; Castaneda, Mario A. Usuga


    We analyse frequency conversion by Bragg scattering numerically including Raman scattering. The frequency configuration that performs the best under influence of Raman noise results in 95% conversion over a 3.25 THz bandwidth with a 2.5-dB noise figure....

  5. Effects of Raman scattering and attenuation in silica fiber-based parametric frequency conversion

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Andersen, Lasse Mejling; Rottwitt, Karsten


    Four-wave mixing in the form of Bragg scattering (BS) has been predicted to enable quantum noise-less frequency conversion by analytic quantum approaches. Using a semi-classical description of quantum noise that accounts for loss and stimulated and spontaneous Raman scattering, which...

  6. An effective Hamiltonian approach to quantum random walk

    Indian Academy of Sciences (India)

    In this article we present an effective Hamiltonian approach for discrete time quantum random walk. A form of the Hamiltonian ... TARUN KANTI GHOSH2. Inter-University Centre for Astronomy and Astrophysics, Ganeshkhind, Pune 411 007, India; Department of Physics, Indian Institute of Technology, Kanpur 208 016, India ...

  7. Randomized Trial on the Effectiveness of Dexamethasone in TMJ Arthrocentesis

    NARCIS (Netherlands)

    Huddleston-Slater, J.J.R.; Vos, L.M.; Stroy, L.P.P.; Stegenga, B.

    The aim of this study was to compare the effectiveness of dexamethasone administration following arthrocentesis of the temporomandibular joint (TMJ) with a placebo (saline). Twenty-eight participants with TMJ arthralgia were randomly assigned to two groups of a parallel double-blind RCT. In both

  8. Application of Random-Effects Probit Regression Models. (United States)

    Gibbons, Robert D.; Hedeker, Donald


    Develops random-effects probit model for case in which outcome of interest is series of correlated binary responses, obtained as product of longitudinal response process where individual is repeatedly classified on binary outcome variable or in multilevel or clustered problems in which individuals within groups are considered to share…

  9. A Randomized Controlled Trial Study on the Effect of Adding ...

    African Journals Online (AJOL)

    A Randomized Controlled Trial Study on the Effect of Adding Dexmedetomidine to Bupivacaine in Supraclavicular Block Using Ultrasound Guidance. ... BACKGROUND: The benefits of regional anesthetic techniques are well established. Use of additives to local anesthetics can prolong these benefits. The aim of this study ...

  10. Computer-Assisted Dieting: Effects of a Randomized Nutrition Intervention (United States)

    Schroder, Kerstin E. E.


    Objectives: To compare the effects of a computer-assisted dieting intervention (CAD) with and without self-management training on dieting among 55 overweight and obese adults. Methods: Random assignment to a single-session nutrition intervention (CAD-only) or a combined CAD plus self-management group intervention (CADG). Dependent variables were…

  11. Regressor and random-effects dependencies in multilevel models

    NARCIS (Netherlands)

    Ebbes, P.; Bockenholt, U; Wedel, M.

    The objectives of this paper are (1) to review methods that can be used to test for different types of random effects and regressor dependencies, (2) to present results from Monte Carlo studies designed to investigate the performance of these methods, and (3) to discuss estimation methods that can

  12. Performance of Random Effects Model Estimators under Complex Sampling Designs (United States)

    Jia, Yue; Stokes, Lynne; Harris, Ian; Wang, Yan


    In this article, we consider estimation of parameters of random effects models from samples collected via complex multistage designs. Incorporation of sampling weights is one way to reduce estimation bias due to unequal probabilities of selection. Several weighting methods have been proposed in the literature for estimating the parameters of…

  13. Measurements of Relativistic Effects in Collective Thomson Scattering at Electron Temperatures less than 1 keV

    Energy Technology Data Exchange (ETDEWEB)

    Ross, James Steven [Univ. of California, San Diego, CA (United States)


    Simultaneous scattering from electron-plasma waves and ion-acoustic waves is used to measure local laser-produced plasma parameters with high spatiotemporal resolution including electron temperature and density, average charge state, plasma flow velocity, and ion temperature. In addition, the first measurements of relativistic modifications in the collective Thomson scattering spectrum from thermal electron-plasma fluctuations are presented [1]. Due to the high phase velocity of electron-plasma fluctuations, relativistic effects are important even at low electron temperatures (Te < 1 keV). These effects have been observed experimentally and agree well with a relativistic treatment of the Thomson scattering form factor [2]. The results are important for the interpretation of scattering measurements from laser produced plasmas. Thomson scattering measurements are used to characterize the hydrodynamics of a gas jet plasma which is the foundation for a broad series of laser-plasma interaction studies [3, 4, 5, 6]. The temporal evolution of the electron temperature, density and ion temperature are measured. The measured electron density evolution shows excellent agreement with a simple adiabatic expansion model. The effects of high temperatures on coupling to hohlraum targets is discussed [7]. A peak electron temperature of 12 keV at a density of 4.7 × 1020cm-3 are measured 200 μm outside the laser entrance hole using a two-color Thomson scattering method we developed in gas jet plasmas [8]. These measurements are used to assess laser-plasma interactions that reduce laser hohlraum coupling and can significantly reduce the hohlraum radiation temperature.

  14. Maxwell-Garnett mixing rule in the presence of multiple scattering: Derivation and accuracy


    Mallet, Pierre; Guérin, Charles-Antoine; Sentenac, Anne


    We give a rigorous and original derivation of the Maxwell-Garnett mixing rule in the dynamical regime for a composite dielectric random medium with small spherical inclusions. For certain configurations of scatterers, we show that contrarily to the common belief, the Maxwell-Garnett formula can remain very accurate at a high concentration of scatterers and incorporate multiple-scattering effects as well as attenuation of the mean field. We provide a realistic numerical example for which this ...

  15. Application of Poisson random effect models for highway network screening. (United States)

    Jiang, Ximiao; Abdel-Aty, Mohamed; Alamili, Samer


    In recent years, Bayesian random effect models that account for the temporal and spatial correlations of crash data became popular in traffic safety research. This study employs random effect Poisson Log-Normal models for crash risk hotspot identification. Both the temporal and spatial correlations of crash data were considered. Potential for Safety Improvement (PSI) were adopted as a measure of the crash risk. Using the fatal and injury crashes that occurred on urban 4-lane divided arterials from 2006 to 2009 in the Central Florida area, the random effect approaches were compared to the traditional Empirical Bayesian (EB) method and the conventional Bayesian Poisson Log-Normal model. A series of method examination tests were conducted to evaluate the performance of different approaches. These tests include the previously developed site consistence test, method consistence test, total rank difference test, and the modified total score test, as well as the newly proposed total safety performance measure difference test. Results show that the Bayesian Poisson model accounting for both temporal and spatial random effects (PTSRE) outperforms the model that with only temporal random effect, and both are superior to the conventional Poisson Log-Normal model (PLN) and the EB model in the fitting of crash data. Additionally, the method evaluation tests indicate that the PTSRE model is significantly superior to the PLN model and the EB model in consistently identifying hotspots during successive time periods. The results suggest that the PTSRE model is a superior alternative for road site crash risk hotspot identification. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Self-Focusing of Elliptical Laser Beam in Collisional Plasma and Its Effect on Stimulated Brillouin Scattering Process (United States)

    Singh, Arvinder; Walia, Keshav


    This paper presents an investigation of self-focusing of elliptical laser beam in a collisional plasma and its effect on stimulated Brillouin scattering (SBS) process. The non-linearity arising through non-uniform heating leads to redistribution of carriers, which modifies the background plasma density profile in a direction transverse to pump beam axis. This modification affects the incident laser beam, ion-acoustic wave and back scattered beam. Non-linear differential equations for the beam width parameters of the pump laser beam, ion-acoustic wave and back scattered beam are set up and solved numerically. It is observed from the analysis that the focusing of waves greatly enhances the SBS back-reflectivity.

  17. Monte Carlo simulation and parameterized treatment on the effect of nuclear elastic scattering in high-energy proton radiography (United States)

    Xu, Hai-Bo; Zheng, Na


    A version of Geant4 has been developed to treat high-energy proton radiography. This article presents the results of calculations simulating the effects of nuclear elastic scattering for various test step wedges. Comparisons with experimental data are also presented. The traditional expressions of the transmission should be correct if the angle distribution of the scattering is Gaussian multiple Coulomb scattering. The mean free path (which depends on the collimator angle) and the radiation length are treated as empirical parameters, according to transmission as a function of thickness obtained by simulations. The results can be used in density reconstruction, which depends on the transmission expressions. Supported by NSAF (11176001) and Science and Technology Developing Foundation of China Academy of Engineering Physics (2012A0202006)

  18. Effective cutoffs for detecting random, partially random, and nonrandom 350-item MMPI--a short form protocols. (United States)

    Pinsoneault, Terry B


    The ability of the 350-item short form Minnesota Multiphasic Personality Inventory-Adolescent (MMPI-A; Butcher et al., 1992) validity scales to detect random protocols was investigated using samples of 250 nonrandom protocols, 250 half-random protocols, and 250 all-random protocols. As the manual warns, long form cutoffs of the Variable Response Inconsistency scale (VRIN) of 75T and the Infrequency scale (F) of 90T were ineffective in detecting random protocols. Alternative cutoffs for F₁ and the truncated VRIN and F scales were investigated. Short form subscales of VRIN and F were developed to improve detection of partially random protocols. An algorithm using alternative cutoffs for the scales and the new subscales was quite effective, detecting 95% of the all-random protocols, 87% of the half-random protocols, and 98% of the nonrandom protocols. A follow-up cross-validation study was conducted that confirmed the effectiveness of the algorithm.

  19. Scattering anomaly in optics

    CERN Document Server

    Silveirinha, Mario G


    In time-reversal invariant electronic systems the scattering matrix is anti-symmetric. This property enables an effect, designated here as "scattering anomaly", such that the electron transport does not suffer from back reflections, independent of the specific geometry of the propagation path or the presence of time-reversal invariant defects. In contrast, for a generic time-reversal invariant photonic system the scattering matrix is symmetric and there is no similar anomaly. Here, it is theoretically proven that despite these fundamental differences there is a wide class of photonic platforms - in some cases formed only by time-reversal invariant media - in which the scattering anomaly can occur. It is shown that an optical system invariant under the action of the composition of the time-reversal, parity and duality operators is characterized by an anti-symmetric scattering matrix. Specific examples of photonic platforms wherein the scattering anomaly occurs are given, and it is demonstrated with full wave n...

  20. Chemotaxis in Dictyostelium discoideum : Effect of Concanavalin A on Chemoattractant Mediated Cyclic GMP Accumulation and Light Scattering Decrease

    NARCIS (Netherlands)

    Mato, José M.; Haastert, Peter J.M. van; Krens, Frans A.; Konijn, Theo M.


    In cells of the cellular slime mold Dictyostelium discoideum concanavalin A (Con A), at a concentration of 100 µg per ml, inhibits folic acid and cyclic AMP induced decrease in light scattering. Con A has no effect on folic acid mediated cyclic GMP accumulation and increases cyclic AMP mediated

  1. X-ray Thomson scattering for partially ionized plasmas including the effect of bound levels

    CERN Document Server

    Nilsen, J; Cheng, K T


    X-ray Thomson scattering is being developed as a method to measure the temperature, electron density, and ionization state of high energy density plasmas such as those used in inertial confinement fusion. Most experiments are currently done at large laser facilities that can create bright X-ray sources, however the advent of the X-ray free electron laser (X-FEL) provides a new bright source to use in these experiments. One challenge with X-ray Thomson scattering experiments is understanding how to model the scattering for partially ionized plasmas in order to include the contributions of the bound electrons in the scattered intensity. In this work we take the existing models of Thomson scattering that include elastic ion-ion scattering and the electron-electron plasmon scattering and add the contribution of the bound electrons in the partially ionized plasmas. We validated our model by analyzing existing beryllium experimental data. We then consider several higher Z materials such as Cr and predict the existe...

  2. Chiral random matrix theory and effective theories of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, K.; Iida, S


    The correlations of the QCD Dirac eigenvalues are studied with use of an extended chiral random matrix model. The inclusion of spatial dependence which the original model lacks enables us to investigate the effects of diffusion modes. We get analytical expressions of level correlation functions with non-universal behavior caused by diffusion modes which is characterized by Thouless energy. Pion mode is shown to be responsible for these diffusion effects when QCD vacuum is considered a disordered medium.

  3. On the Effectiveness of the Dynamic Force Adjustment for Reducing the Scatter of Instrumented Charpy Results

    Energy Technology Data Exchange (ETDEWEB)

    Lucon, E.


    One of the key factors for obtaining reliable instrumented Charpy results is the calibration of the instrumented striker. An interesting alternative to the conventional static calibration recommended by the standards is the Dynamic Force Adjustment (DFA), in which forces and displacements are iteratively adjusted until equality is achieved between absorbed energies calculated under the test record (Wt) and measured by the machine encoder (KV). In this study, this procedure has been applied to the instrumented data obtained by 10 international laboratories using notched and precracked Charpy specimens, in the framework of a Coordinated Research Project (CRP8) of IAEA. DFA is extremely effective in reducing the between-laboratory scatter for both general yield and maximum forces. The effect is less significant for dynamic reference temperatures measured from precracked Charpy specimens using the Master Curve procedure, but a moderate reduction of the standard deviation is anyway observed. It is shown that striker calibration is a prominent contribution to the interlaboratory variability of instrumented impact forces, particularly in the case of maximum forces.

  4. Electron impact ionization in the Martian atmosphere: Interplay between scattering and crustal magnetic field effects (United States)

    Lillis, Robert J.; Fang, Xiaohua


    Precipitating electrons are typically the dominant source of energy input into Mars' nighttime upper atmosphere, with consequences for atmospheric and ionospheric structure, composition, chemistry, and electrodynamics. Mars' spatially heterogeneous crustal magnetic fields affect the fluxes of precipitating electrons, via both the magnetic mirror force and Gauss' law of conservation of magnetic flux. We use a kinetic electron transport model to examine ionization rate profiles that result from the combination of these magnetic effects and elastic and inelastic scattering by atmospheric neutrals. Specifically, we calculate ionization rates as a function of altitude, crustal magnetic field strength, and the initial energy and pitch angle of the precipitating electrons, covering the relevant ranges of these parameters. Several complex behaviors are exhibited, including bifurcating ionization peaks with distinct characteristics and energy-dependent and crustal field strength-dependent increases in ionization with decreasing pitch angle. Elucidating such behavior is important for understanding the effect of Mars' unique crustal fields on the Mars upper atmosphere and ionosphere, both to predict the consequences of measured electron precipitation and to enable, for the first time, downward coupling of global plasma models with thermosphere-ionosphere models.

  5. Effective diffusion equation in a random velocity field (United States)

    Vinals, Jorge; Sekerka, Robert F.


    The effects are studied of assumed random velocity fields on diffusion in a binary fluid. Random velocity fields can result, for example, from the high-frequency components of residual accelerations onboard spacecraft (often called g-jitter). An effective diffusion equation is derived for an average concentration which includes spatial and temporal correlations induced by the fluctuating velocity fields assumed to be Gaussianly distributed. The resulting equation becomes nonlocal, and if correlations between different components of the velocity field exist, it is also anisotropic. The simple limiting case of short correlation times is discussed and an effective diffusivity is obtained which reflects the enhanced mixing caused by the velocity fields. The results obtained in the limit of short correlation times are valid even if the probability distribution of the velocity field is not Gaussian.

  6. Effect of particle shape and structure on the results of single-particle light-scattering size analysis. (United States)

    Umhauer, H; Bottlinger, M


    To evaluate quantitatively the influence exerted by the shape and structure of nonspherical, nonideal particles on the results of single-particle scattered-light size analysis, measurements were conducted with individual particles of different materials (glass, limestone, and quartz). For this purpose, the particles were suspended in an electrodynamic balance and repeatedly passed through the analyzer's measuring volume with a continually changing random orientation. The scattered-light signal spectra thus obtained specify the probability with which a certain pulse height is induced when the particle passes once through the measuring volume at a given coincidental orientation. The spectra reflect the material-characteristic influence. They allow the loss of resolution of common scattered-light size analyses to be assessed and algorithms (matrices) to be compiled with which the shape and structure influence may be mathematically eliminated. Because a shape and structure independent size parameter is also determined from the individual particles, exact calibration curves can be derived in which the shape and structure influence are incorporated.

  7. Effect of spatio-energy correlation in PCD due to charge sharing, scatter, and secondary photons (United States)

    Rajbhandary, Paurakh L.; Hsieh, Scott S.; Pelc, Norbert J.


    Charge sharing, scatter and fluorescence events in a photon counting detector (PCD) can result in multiple counting of a single incident photon in neighboring pixels. This causes energy distortion and correlation of data across energy bins in neighboring pixels (spatio-energy correlation). If a "macro-pixel" is formed by combining multiple small pixels, it will exhibit correlations across its energy bins. Charge sharing and fluorescence escape are dependent on pixel size and detector material. Accurately modeling these effects can be crucial for detector design and for model based imaging applications. This study derives a correlation model for the multi-counting events and investigates the effect in virtual non-contrast and effective monoenergetic imaging. Three versions of 1 mm2 square CdTe macro-pixel were compared: a 4×4 grid, 2×2 grid, or 1×1 composed of pixels with side length 250 μm, 500 μm, or 1 mm, respectively. The same flux was applied to each pixel, and pulse pile-up was ignored. The mean and covariance matrix of measured photon counts is derived analytically using pre-computed spatio-energy response functions (SERF) estimated from Monte Carlo simulations. Based on the Cramer-Rao Lower Bound, a macro-pixel with 250×250 μm2 sub-pixels shows 2.2 times worse variance than a single 1 mm2 pixel for spectral imaging, while its penalty for effective monoenergetic imaging is <10% compared to a single 1 mm2 pixel.

  8. The effect of electron-surface scattering and thiol adsorption on the electrical resistivity of gold ultrathin films

    Energy Technology Data Exchange (ETDEWEB)

    Henriquez, Ricardo, E-mail: [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile); Del Campo, Valeria; Gonzalez-Fuentes, Claudio [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile); Correa-Puerta, Jonathan [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Av. Universidad 330, Curauma, Valparaíso (Chile); Moraga, Luis [Universidad Central de Chile, Toesca 1783, Santiago 8370178 (Chile); Flores, Marcos [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Segura, Rodrigo [Instituto de Química y Bioquímica, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso (Chile); Donoso, Sebastián; Marín, Francisca; Bravo, Sergio; Häberle, Patricio [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso 2390123 (Chile)


    Highlights: • We prepared ultra thin films (10 nm) on mica on top of a chromium seedlayer (<1 nm). • We prepared samples with different topographies controlling the substrate temperature. • We studied the contribution of the different scattering mechanims on the resistivity. • We developed a discernment method based on thiol adsorption. - Abstract: In order to study the effect of electron-surface scattering in gold ultrathin films (∼10 nm), we have prepared a set of Au samples on mica on top of a chromium seedlayer (<1 nm). Chromium is added as a metallic surfactant which enables surpassing the electric percolation threshold for substrate temperatures above room temperature. We prepared samples with the same thickness but different topographies setting different substrate temperatures. These modifications modulate the contributions of the different electronic scattering mechanisms to the film resistivity. A second set of gold thin films deposited on mica at room temperature, with different thicknesses between 8 and 100 nm, was also prepared to compare the resisitivities of both sets through Mayadas and Shatzkes theory. We found that in samples with thicknesses below 15 nm, the electron-surface scattering is indeed the dominant mechanism influencing the film resistivity. To obtain further evidence of this prevalence, we developed a discrimination method based on thiol adsorption. The film with the highest resistivity increase is the sample in which electron-surface scattering is dominant. With this method, we observed that a large enhancement of the electron-surface scattering not only occurs in samples with large diameters grains, but also if the film has a reduced surface roughness.​.

  9. The effect of bound states on X-ray Thomson scattering for partially ionized plasmas

    CERN Document Server

    Nilsen, J; Cheng, K T


    X-ray Thomson scattering is being developed as a method to measure the temperature, electron density, and ionization state of high energy density plasmas such as those used in inertial confinement fusion. X-ray laser sources have always been of interest because of the need to have a bright monochromatic x-ray source to overcome plasma emission and eliminate other lines in the background that complicate the analysis. With the advent of the xray free electron laser (X-FEL) at the SLAC Linac Coherent Light Source (LCLS) and other facilities coming online worldwide, we now have such a source available in the keV regime. Most Thomson scattering codes used to model experimental data greatly simplify or neglect the contributions of the bound electrons to the scattered intensity. In this work we take the existing models of Thomson scattering that include elastic ion-ion scattering and inelastic electron-electron scattering and add the contribution of bound electrons in the partially ionized plasmas. To date, most exp...

  10. Effect of corneal light scatter on vision: a review of the literature

    Directory of Open Access Journals (Sweden)

    Leopoldo Spadea


    Full Text Available The cornea is the transparent connective tissue window at the front of the eye. The physiological role of the cornea is to conduct external light into the eye, focus it, together with the lens, onto the retina, and to provide rigidity to the entire eyeball. Therefore, good vision requires maintenance of the transparency and proper refractive shape of the cornea. The surface structures irregularities can be associated with wavefront aberrations and scattering errors. Light scattering in the human cornea causes a reduction of visual quality. In fact, the cornea must be transparent and maintain a smooth and stable curvature since it contributes to the major part of the focusing power of the eye. In most cases, a simple examination of visual acuity cannot demonstrate the reduction of visual quality secondary light scattering. In fact, clinical techniques for examining the human cornea in vivo have greatly expanded over the last few decades. The measurement of corneal back scattering qualifies the degree of corneal transparency. The measurement of corneal forward-scattering quantifies the amount of visual impairment that is produced by the alteration of transparency. The aim of this study was to review scattering in the human cornea and methods of measuring it.

  11. Scattering effect in radiative heat transfer during selective laser sintering of polymers (United States)

    Liu, Xin; Boutaous, M'hamed; Xin, Shihe


    The aim of this work is to develop an accurate model to simulate the selective laser sintering (SLS) process, in order to understand the multiple phenomena occurring in the material and to study the influence of each parameter on the quality of the sintered parts. A numerical model, coupling radiative and conductive heat transfers in a polymer powder bed providing a local temperature field, is proposed. To simulate the polymer sintering by laser heating as in additive manufacturing, a double-lines scanning of a laser beam over a thin layer of polymer powder is studied. An effective volumetric heat source, using a modified Monte Carlo method, is estimated from laser radiation scattering and absorption in a semi-transparent polymer powder bed. In order to quantify the laser-polymer interaction, the heating and cooling of the material is modeled and simulated with different types heat sources by both finite elements method (FEM) and discrete elements method (DEM). To highlight the importance of introducing a semi-transparent behavior of such materials and in order to validate our model, the results are compared with works taken from the literature.

  12. Effects of aggregation on the permittivity of random media containing monodisperse spheres (United States)

    Doyle, Timothy E.; Tew, Adam T.; Jain, Rahul; Robinson, David A.


    Numerical simulations were used to calculate the effective permittivities of three-dimensional random particle suspensions containing up to 2440 particles and exhibiting two types of particle aggregation. The particles were modeled as 200 μm spheres that were aggregated into either large spherical clusters or into foam-type microstructures with large spherical voids. Multiple scattering of 0.01-10.0 GHz electromagnetic fields was simulated using a first-principles iterative multipole approach with matrix and particle permittivities of 1.0 and 8.5, respectively. The computational results showed both significant and highly significant trends. Aggregation into spherical clusters decreased the effective permittivity by up to 3.2±0.2%, whereas aggregation into foam-type microstructures increased the effective permittivity by up to 3.0±1.6%. The effective permittivity trends exhibited little change with frequency. These results were compared to effective medium approximations that predicted higher permittivities than those from the simulations and showed opposite trends for cluster aggregation. Three theories are proposed to explain the simulation results. The first theory invokes a waveguidelike mechanism. The simulations indicate that the wave fields propagate more through the continuous paths of greater or lesser particle density created by aggregation, rather than through the isolated particle clusters or large voids. This quasicontinuous phase, or quasimatrix, therefore behaves like a random waveguide structure in the material. A second theory is proposed where the quasicontinuous phase governs the behavior of the system by a percolationlike process. In this theory, the multipole interactions are modeled as the percolation of virtual charges tunneling from one particle to another. A third mechanism for the permittivity changes is also proposed involving collective polarization effects associated with the particle clusters or large voids. The simulation results

  13. An examination of errors in computed water-leaving radiances due to a simplified treatment of water Raman scattering effects (United States)

    Bismarck, Jonas von; Fischer, Jürgen


    Studies in the past have shown that solar shortwave radiation that has been Raman scattered in the ocean, and therefore undergone a wavelength shift, can contribute significantly to the signals observed by remote sensing satellites. While radiative transfer models that qualitatively approximate the effect of water Raman scattering on the water leaving irradiance have been available for a while, we have developed a new version of the radiative transfer code MOMO, which enables the accurate and fully angle resolved inclusion of inelastic scattering sources, and therefore allows detailed quantitative analyses of the effect on the light field in the ocean-atmosphere system. This article focuses on a study performed with this new model on the impact of azimuthally averaging the Raman scattering phase function, which is done in some RT models and significantly decreases computation time, on the water-leaving radiance. At the request of the authors and Proceedings Editors the above article has been updated to include a number of post-publication amendments. Changes made to the previously published article are detailed in the pages attached to the end of the updated article PDF file. The updated article was re-published on 15 August 2013.

  14. Effects of Check and Connect on Attendance, Behavior, and Academics: A Randomized Effectiveness Trial (United States)

    Maynard, Brandy R.; Kjellstrand, Elizabeth K.; Thompson, Aaron M.


    Objectives: This study examined the effects of Check & Connect (C&C) on the attendance, behavior, and academic outcomes of at-risk youth in a field-based effectiveness trial. Method: A multisite randomized block design was used, wherein 260 primarily Hispanic (89%) and economically disadvantaged (74%) students were randomized to treatment…

  15. Magnitude and effects of X-ray scatter of a cone-beam micro-CT for small animal imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Y.C. [Institute of Nuclear Energy Research, Longtan 32546, Taiwan (China); Jan, M.L. [Institute of Nuclear Energy Research, Longtan 32546, Taiwan (China); Chen, K.W. [Institute of Nuclear Energy Research, Longtan 32546, Taiwan (China); Cheng, Y.D. [Department of Nuclear Science, National Tsing-Hua University, Hsinchu 30043, Taiwan (China); Chuang, K.S. [Department of Nuclear Science, National Tsing-Hua University, Hsinchu 30043, Taiwan (China); Fu, Y.K. [Institute of Nuclear Energy Research, Longtan 32546, Taiwan (China)]. E-mail:


    We have developed a micro-CT system to provide high-resolution and anatomic information to combine with a microPET'' (registered) R4 system. This study was to evaluate the magnitude and effects of scatter for low kVp X-ray in this cone-beam micro-CT system. Slit collimators were used to simulate fan-beam micro-CT for comparison. The magnitudes of X-ray scatter were measured using the beam-stop method and were estimated by polynomial-fitting extrapolation to 0 mm size of stoppers. The scatter-to-primary ratio at center of the cone-beam system were 45% and 20% for rat and mouse phantoms, respectively, and were reduced to 5.86% and 4.2% in fan-beam geometric setup. The effects of X-ray scatter on image uniformity and contrast ratio were evaluated also. The uniformity response was examined by the profile of the reconstructed image. The degrees of 'cupping' in the fan-beam and cone-beam conditions were 1.75% and 3.81%, respectively, in rat phantom. A contrast phantom consisting of four inserts with physical densities similar to that of acrylic was used for measuring the effect of X-ray scatter on image contrast. Contrast ratios of the inserts and acrylic in cone-beam setup degraded 36.9% in average compared with fan-beam setup. A tumor-bearing mouse was scanned by the micro-CT system. The tumor-to-background contrast ratios were measured to be 0.331 and 0.249, respectively, with fan-beam and cone-beam setups.

  16. Numerical Studies of Scattering Properties of Leaves and Leaf Moisture Influences on the Scattering at Microwave Wavelengths (United States)

    Lin, Bing; Hu, Yongxiang; Sun, Wenbo; Min, Qilong


    This study uses 3-dimensional finite difference time domain method to accurately calculate single-scattering properties of randomly orientated leaves and evaluate the influences of vegetation water content (VWC) on these properties at 19 and 37 GHz frequencies. The studied leaves are assumed to be thin elliptic disks with two different sizes and have various VWC values. Although the leaf moisture produces considerable absorption during scattering processes, the effective efficiencies of extinction and scattering of leaves still near-linearly increase with VWC. Calculated asymmetry factors and phase functions indicate that there are significant amounts of scattering at large scattering angles in microwave wavelengths, which provides good opportunities for off-nadir microwave remote sensing of forests. This study lays a basic foundation in future quantifications of the relations between satellite measurements and physical properties of vegetation canopies.

  17. Three-dimensional simulation of the Ring effect in observations of scattered sun light using Monte Carlo radiative transfer models

    Directory of Open Access Journals (Sweden)

    T. Deutschmann


    Full Text Available We present a new technique for the quantitative simulation of the "Ring effect" for scattered light observations from various platforms and under different atmospheric situations. The method is based on radiative transfer calculations at only one wavelength λ0 in the wavelength range under consideration, and is thus computationally fast. The strength of the Ring effect is calculated from statistical properties of the photon paths for a given situation, which makes Monte Carlo radiative transfer models in particular appropriate. We quantify the Ring effect by the so called rotational Raman scattering probability, the probability that an observed photon has undergone a rotational Raman scattering event. The Raman scattering probability is independent from the spectral resolution of the instrument and can easily be converted into various definitions used to characterise the strength of the Ring effect. We compare the results of our method to the results of previous studies and in general good quantitative agreement is found. In addition to the simulation of the Ring effect, we developed a detailed retrieval strategy for the analysis of the Ring effect based on DOAS retrievals, which allows the precise determination of the strength of the Ring effect for a specific wavelength while using the spectral information within a larger spectral interval around the selected wavelength. Using our technique, we simulated synthetic satellite observation of an atmospheric scenario with a finite cloud illuminated from different sun positions. The strength of the Ring effect depends systematically on the measurement geometry, and is strongest if the satellite points to the side of the cloud which lies in the shadow of the sun.

  18. [Randomized controlled trials terminated prematurely: beneficial therapy effects]. (United States)

    Kluth, L A; Rink, M; Ahyai, S A; Fisch, M; Shariat, S F; Dahm, P


    Randomized controlled trials (RCTs) stopped prematurely for beneficial therapy effects are becoming increasingly more prevalent in the urological literature and often receive great attention in the public and medical media. Urologists who practice evidence-based medicine should be aware of the potential bias and the different reasons why and how early termination of RCTs can and will affect the results. This review provides insights into the challenges clinical urologists face by interpreting the results of prematurely terminated RCTs.

  19. Effects of random noise in a dynamical model of love

    Energy Technology Data Exchange (ETDEWEB)

    Xu Yong, E-mail: [Department of Applied Mathematics, Northwestern Polytechnical University, Xi' an 710072 (China); Gu Rencai; Zhang Huiqing [Department of Applied Mathematics, Northwestern Polytechnical University, Xi' an 710072 (China)


    Highlights: > We model the complexity and unpredictability of psychology as Gaussian white noise. > The stochastic system of love is considered including bifurcation and chaos. > We show that noise can both suppress and induce chaos in dynamical models of love. - Abstract: This paper aims to investigate the stochastic model of love and the effects of random noise. We first revisit the deterministic model of love and some basic properties are presented such as: symmetry, dissipation, fixed points (equilibrium), chaotic behaviors and chaotic attractors. Then we construct a stochastic love-triangle model with parametric random excitation due to the complexity and unpredictability of the psychological system, where the randomness is modeled as the standard Gaussian noise. Stochastic dynamics under different three cases of 'Romeo's romantic style', are examined and two kinds of bifurcations versus the noise intensity parameter are observed by the criteria of changes of top Lyapunov exponent and shape of stationary probability density function (PDF) respectively. The phase portraits and time history are carried out to verify the proposed results, and the good agreement can be found. And also the dual roles of the random noise, namely suppressing and inducing chaos are revealed.

  20. Spot Scanning and Passive Scattering Proton Therapy: Relative Biological Effectiveness and Oxygen Enhancement Ratio in Cultured Cells

    Energy Technology Data Exchange (ETDEWEB)

    Iwata, Hiromitsu, E-mail: [Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya (Japan); Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya (Japan); Ogino, Hiroyuki [Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya (Japan); Hashimoto, Shingo [Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya (Japan); Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya (Japan); Yamada, Maho [Department of Radiation Oncology, Nagoya City West Medical Center, Nagoya (Japan); Shibata, Hiroki; Yasui, Keisuke [Department of Proton Therapy Technology, Nagoya Proton Therapy Center, Nagoya (Japan); Toshito, Toshiyuki; Omachi, Chihiro [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya (Japan); Tatekawa, Kotoha [Department of Radiology, Kyoto Prefectural University of Medicine, Kyoto (Japan); Manabe, Yoshihiko [Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya (Japan); Mizoe, Jun-etsu [Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya (Japan); Shibamoto, Yuta [Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya (Japan)


    Purpose: To determine the relative biological effectiveness (RBE), oxygen enhancement ratio (OER), and contribution of the indirect effect of spot scanning proton beams, passive scattering proton beams, or both in cultured cells in comparison with clinically used photons. Methods and Materials: The RBE of passive scattering proton beams at the center of the spread-out Bragg peak (SOBP) was determined from dose-survival curves in 4 cell lines using 6-MV X rays as controls. Survival of 2 cell lines after spot scanning and passive scattering proton irradiation was then compared. Biological effects at the distal end region of the SOBP were also investigated. The OER of passive scattering proton beams and 6 MX X rays were investigated in 2 cell lines. The RBE and OER values were estimated at a 10% cell survival level. The maximum degree of protection of radiation effects by dimethyl sulfoxide was determined to estimate the contribution of the indirect effect against DNA damage. All experiments comparing protons and X rays were made under the same biological conditions. Results: The RBE values of passive scattering proton beams in the 4 cell lines examined were 1.01 to 1.22 (average, 1.14) and were almost identical to those of spot scanning beams. Biological effects increased at the distal end of the SOBP. In the 2 cell lines examined, the OER was 2.74 (95% confidence interval, 2.56-2.80) and 3.08 (2.84-3.11), respectively, for X rays, and 2.39 (2.38-2.43) and 2.72 (2.69-2.75), respectively, for protons (P<.05 for both cells between X rays and protons). The maximum degree of protection was significantly higher for X rays than for proton beams (P<.05). Conclusions: The RBE values of spot scanning and passive scattering proton beams were almost identical. The OER was lower for protons than for X rays. The lower contribution of the indirect effect may partly account for the lower OER of protons.

  1. Estimating overall exposure effects for the clustered and censored outcome using random effect Tobit regression models (United States)

    Wang, Wei; Griswold, Michael E.


    The random effect Tobit model is a regression model that accommodates both left- and/or right-censoring and within-cluster dependence of the outcome variable. Regression coefficients of random effect Tobit models have conditional interpretations on a constructed latent dependent variable and do not provide inference of overall exposure effects on the original outcome scale. Marginalized random effects model (MREM) permits likelihood-based estimation of marginal mean parameters for the clustered data. For random effect Tobit models, we extend the MREM to marginalize over both the random effects and the normal space and boundary components of the censored response to estimate overall exposure effects at population level. We also extend the ‘Average Predicted Value’ method to estimate the model-predicted marginal means for each person under different exposure status in a designated reference group by integrating over the random effects and then use the calculated difference to assess the overall exposure effect. The maximum likelihood estimation is proposed utilizing a quasi-Newton optimization algorithm with Gauss-Hermite quadrature to approximate the integration of the random effects. We use these methods to carefully analyze two real datasets. PMID:27449636

  2. Effect of random vacancies on the electronic properties of graphene and T graphene: a theoretical approach (United States)

    Sadhukhan, B.; Nayak, A.; Mookerjee, A.


    In this communication we present together four distinct techniques for the study of electronic structure of solids: the tight-binding linear muffin-tin orbitals, the real space and augmented space recursions and the modified exchange-correlation. Using this we investigate the effect of random vacancies on the electronic properties of the carbon hexagonal allotrope, graphene, and the non-hexagonal allotrope, planar T graphene. We have inserted random vacancies at different concentrations, to simulate disorder in pristine graphene and planar T graphene sheets. The resulting disorder, both on-site (diagonal disorder) as well as in the hopping integrals (off-diagonal disorder), introduces sharp peaks in the vicinity of the Dirac point built up from localized states for both hexagonal and non-hexagonal structures. These peaks become resonances with increasing vacancy concentration. We find that in presence of vacancies, graphene-like linear dispersion appears in planar T graphene and the cross points form a loop in the first Brillouin zone similar to buckled T graphene that originates from π and π* bands without regular hexagonal symmetry. We also calculate the single-particle relaxation time, τ (ěc {q}) of ěc {q} labeled quantum electronic states which originates from scattering due to presence of vacancies, causing quantum level broadening.

  3. Random Matrix Theoretic Approaches to Sensor Fusion for Sensing and Surveillance in Highly Cluttered Environments (United States)


    Squared Error (MSE) tracking performance for direction of arrival estimation in the presence of noise and missing data; see Fig. 5. 6) We have...scatter in random directions, thereby hindering its passage. As the thickness of a slab of highly scattering random medium increases, this effect

  4. Simulation model to analyze the scatter radiation effects on breast cancer diagnosis by CAD system (United States)

    Irita, Ricardo T.; Frere, Annie F.; Fujita, Hiroshi


    One of factors that more affect the radiographic image quality is the scatter radiation produced by interaction between the x-ray and the radiographed object. Recently the Computer Aided Diagnosis (CAD) Systems are coming to aid the detection of breast small details. Nevertheless, we not sure how much the scatter radiation decrease the efficiency of this systems. This work presents a model in order to quantify the scatter radiation and find it relation between CAD's results used for the microcalcification detection. We simulated scatter photons that reaches the film and we added it to the mammography image. The new images were processed and the alterations of the CAD's results were analyzed. The information loss to breast composed by 80 percent adipose tissue was 0,0561 per each centimeter increased in the breast's thickness. We calculated these same data considering a proportion variation of adipose tissue and considering the breast composition of 90 percent and 70 percent the loss it would be of 0.0504 and 0.07559 per increased cm, respectively. We can increase the wanted scattered radiation to any image with its own characteristics and analyze the disturbances that it can bring to the visual inspection or the automatic detection (CAD system) efficiently.

  5. The relative effects of particles and turbulence on acoustic scattering from deep-sea hydrothermal vent plumes. (United States)

    Xu, Guangyu; Di Iorio, Daniela


    Acoustic methods are applied to the investigation and monitoring of a vigorous hydrothermal plume within the Main Endeavor vent field at the Endeavor segment of the Juan de Fuca Ridge. Forward propagation and scattering from suspended particulates using Rayleigh scattering theory is shown to be negligible (log-amplitude variance σ(χ) (2)~10(-7)) compared to turbulence induced by temperature fluctuations (σ(χ) (2)~0.1). The backscattering from turbulence is then quantified using the forward scattering derived turbulence level, which gives a volume backscattering strength of s(V)=6.5 × 10(-8) m(-1). The volume backscattering cross section from particulates can range from s(V)=3.3 × 10(-6) to 7.2 × 10(-10) m(-1) depending on the particle size. These results show that forward scatter acoustic methods in hydrothermal vent applications can be used to quantify turbulence and its effect on backscatter measurements, which can be a dominant factor depending on the particle size and its location within the plume. © 2011 Acoustical Society of America

  6. The effect of non-local electron scattering on the current-perpendicular-to-plane-mode magnetoresistance of magnetic multilayers (United States)

    Bozec, D.; Walker, M. J.; Howson, M. A.; Hickey, B. J.; Shatz, S.; Wiser, N.


    We have carried out an experimental and theoretical study of non-local electron scattering in magnetic multilayers by measuring the magnetoresistance MR(H) in the CPP (current-perpendicular-to-plane) mode for two samples consisting of different magnetic layers (M1, M2) separated by non-magnetic layers (NM). For the two samples, the ordering of the layers was as follows: [M1/NM/M2/NM]N and [M1/NM]N[M2/NM]N. If the non-local character of the electron scattering were unimportant, the two samples would yield identical curves for MR(H) in the CPP mode. However, our measured MR(H) curves are completely different for the two samples. This demonstrates the importance of non-local electron scattering. For our measurements, M1 = Fe(50 Å), M2 = Co(20 Å), NM = Cu(200 Å) for Fe-Co samples, and M1 = Co(10 Å), M2 = Co(60 Å), NM = Cu(200 Å) for the Co-Co samples. To confirm our ideas, we calculated MR(H), including the effect of non-local electron scattering, and obtained quantitative agreement with experiment.

  7. Thomson Scattering

    NARCIS (Netherlands)

    Donne, A. J. H.


    Thomson scattering is a very powerful diagnostic which is applied at nearly every magnetic confinement device. Depending on the experimental conditions different plasma parameters can be diagnosed. When the wave vector is much larger than the plasma Debye length, the total scattered power is

  8. Polymer boosting effect in the droplet phase studied by small-angle neutron scattering

    CERN Document Server

    Frielinghaus, H; Allgaier, J; Richter, D; Jakobs, B; Sottmann, T; Strey, R


    Small-angle neutron-scattering experiments were performed in order to obtain the six partial scattering functions of a droplet microemulsion containing water, decane, C sub 1 sub 0 E sub 4 surfactant and PEP sub 5 -PEO sub 8 sub 0. We systematically varied the contrast around the polymer contrast, where only the polymer becomes visible, and we also measured bulk and film contrasts. With the singular value decomposition method we could extract the desired six partial scattering functions from the 15 measured spectra. We find a sphere-shell-shell structure of the droplets, where the innermost sphere consists of oil, the middle shell of surfactant and the outer shell is a depletion zone where the polymer is almost not present. (orig.)

  9. Variational Calculation of Effective Parameters in Random Porous Media (United States)

    Hristopulos, Dionissios T.; Christakos, George


    Effective parameters are used in stochastic hydrology and petroleum engineering as estimates of the coarse-grained behavior of fluid flow and transport. Stochastic effective parameter estimation involves averaging over the local heterogeneity. Explicit evaluation methods are often based on low order perturbation expansions. We obtain more general estimates using a variational scheme that employs auxiliary probability measures. The average over the local fluctuations is evaluated by means of the logarithm transform and the replica trick. The equations satisfied by the effective parameters are obtained variationally from an effective free energy functional. We use this method for the evaluation of the effective permeability of random porous media with Gaussian local fluctuations. The resulting equations are solved explicitly in specific cases, and the results are compared with leading-order perturbation estimates and experimental data. Explicit finite-size expressions are obtained using momentum-space filters. The implications of the finite size behavior for the scaleup problem are discussed.

  10. Nonparametric Estimation of Distributions in Random Effects Models

    KAUST Repository

    Hart, Jeffrey D.


    We propose using minimum distance to obtain nonparametric estimates of the distributions of components in random effects models. A main setting considered is equivalent to having a large number of small datasets whose locations, and perhaps scales, vary randomly, but which otherwise have a common distribution. Interest focuses on estimating the distribution that is common to all datasets, knowledge of which is crucial in multiple testing problems where a location/scale invariant test is applied to every small dataset. A detailed algorithm for computing minimum distance estimates is proposed, and the usefulness of our methodology is illustrated by a simulation study and an analysis of microarray data. Supplemental materials for the article, including R-code and a dataset, are available online. © 2011 American Statistical Association.

  11. Effect of electron correlation on positronium formation in positron-helium scattering

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhuri, P.; Adhikari, S.K. [Universidad Estadual Paulista, Sao Paulo (Brazil). Inst. de Fisica Teorica; Talukdar, B.; Bhattacharyya, S. [Department of Physics, Visva Bharati University, Santiniketan 731235 (India)


    A three-parameter correlated wave function for the helium ground state is used to study the scattering reaction e{sup +}+He{yields}He{sup +}+Ps, where Ps stands for positronium atom. An exact analytical expression is constructed for the first Born scattering amplitude for Ps formation from helium. Based on this numerical results are presented for both differential and total cross-sections. It is demonstrated that the inner electronic correlation of the target atom plays a crucial role in explaining the discrepancy between theory and experiment. (orig.) 13 refs.

  12. Purely bianisotropic scatterers (United States)

    Albooyeh, M.; Asadchy, V. S.; Alaee, R.; Hashemi, S. M.; Yazdi, M.; Mirmoosa, M. S.; Rockstuhl, C.; Simovski, C. R.; Tretyakov, S. A.


    The polarization response of molecules or meta-atoms to external electric and magnetic fields, which defines the electromagnetic properties of materials, can either be direct (electric field induces electric moment and magnetic field induces magnetic moment) or indirect (magnetoelectric coupling in bianisotropic scatterers). Earlier studies suggest that there is a fundamental bound on the indirect response of all passive scatterers: It is believed to be always weaker than the direct one. In this paper, we prove that there exist scatterers which overcome this bound substantially. Moreover, we show that the amplitudes of electric and magnetic polarizabilities can be negligibly small as compared to the magnetoelectric coupling coefficients. However, we prove that if at least one of the direct-excitation coefficients vanishes, magnetoelectric coupling effects in passive scatterers cannot exist. Our findings open a way to a new class of electromagnetic scatterers and composite materials.

  13. Effect of random surface inhomogeneities on spectral properties of dielectric-disk microresonators: theory and modeling at millimeter wave range. (United States)

    Ganapolskii, E M; Eremenko, Z E; Tarasov, Yu V


    The influence of random axially homogeneous surface roughness on spectral properties of dielectric resonators of circular disk form is studied both theoretically and experimentally. To solve the equations governing the dynamics of electromagnetic fields, the method of eigenmode separation is applied previously developed with reference to inhomogeneous systems subject to arbitrary external static potential. We prove theoretically that it is the gradient mechanism of wave-surface scattering that is highly responsible for nondissipative loss in the resonator. The influence of side-boundary inhomogeneities on the resonator spectrum is shown to be described in terms of effective renormalization of mode wave numbers jointly with azimuth indices in the characteristic equation. To study experimentally the effect of inhomogeneities on the resonator spectrum, the method of modeling in the millimeter wave range is applied. As a model object, we use a dielectric disk resonator (DDR) fitted with external inhomogeneities randomly arranged at its side boundary. Experimental results show good agreement with theoretical predictions as regards the predominance of the gradient scattering mechanism. It is shown theoretically and confirmed in the experiment that TM oscillations in the DDR are less affected by surface inhomogeneities than TE oscillations with the same azimuth indices. The DDR model chosen for our study as well as characteristic equations obtained thereupon enable one to calculate both the eigenfrequencies and the Q factors of resonance spectral lines to fairly good accuracy. The results of calculations agree well with obtained experimental data.

  14. Time-Resolved Study of the Surface-Enhanced Raman Scattering Effect of Silver Nanoparticles Generated in Voltammetry Experiments


    Ibáñez, David; Fernández Blanco, Ana Cristina; Heras, Aránzazu; Colina, Álvaro


    UV–vis absorption and Raman spectroelectrochemistry have been used to study silver nanoparticle (AgNP) electrodeposition, allowing a better understanding about the metal nanoparticle (NP) formation process and its influence on the surface-enhanced Raman scattering (SERS) effect. These techniques have provided in situ information related to the synthesis of AgNPs by cyclic voltammetry. With a marker, such as cyanide anion (CN–), Raman spectroscopy has allowed us to study all changes that take ...

  15. Letters: Comment on "Effects of multi-scattering on the performance of a single-beam acoustic manipulation device". (United States)

    Mitri, F G


    The concern addressed in the present commentary is to point out the omission of the azimuthal component Fφ of the axial acoustic radiation force provided in M. Azarpeyvand, M. A. Alibakhshi, R. Self, "Effects of multi-scattering on the performance of a single-beam acoustic manipulation device," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, vol. 59, no. 8, pp. 1741-1749, 2012, which may suggest a miscalculation of the radiation force function Ym and its related numerical computations.

  16. Extracting chemical information from spectral data with multiplicative light scattering effects by optical path-length estimation and correction. (United States)

    Chen, Zeng-Ping; Morris, Julian; Martin, Elaine


    When analyzing complex mixtures that exhibit sample-to-sample variability using spectroscopic instrumentation, the variation in the optical path length, resulting from the physical variations inherent within the individual samples, will result in significant multiplicative light scattering perturbations. Although a number of algorithms have been proposed to address the effect of multiplicative light scattering, each has associated with it a number of underlying assumptions, which necessitates additional information relating to the spectra being attained. This information is difficult to obtain in practice and frequently is not available. Thus, with a view to removing the need for the attainment of additional information, a new algorithm, optical path-length estimation and correction (OPLEC), is proposed. The methodology is applied to two near-infrared transmittance spectral data sets (powder mixture data and wheat kernel data), and the results are compared with the extended multiplicative signal correction (EMSC) and extended inverted signal correction (EISC) algorithms. Within the study, it is concluded that the EMSC algorithm cannot be applied to the wheat kernel data set due to core information for the implementation of the algorithm not being available, while the analysis of the powder mixture data using EISC resulted in incorrect conclusions being drawn and hence a calibration model whose performance was unacceptable. In contrast, OPLEC was observed to effectively mitigate the detrimental effects of physical light scattering and significantly improve the prediction accuracy of the calibration models for the two spectral data sets investigated without any additional information pertaining to the calibration samples being required.

  17. Tunneling effects in resonant acoustic scattering of an air bubble in unbounded water

    Directory of Open Access Journals (Sweden)



    Full Text Available Abstract The problem of acoustic scattering of a gaseous spherical bubble immersed within unbounded liquid surrounding is considered in this work. The theory of partial wave expansion related to this problem is revisited. A physical model based on the analogy between acoustic scattering and potential scattering in quantum mechanics is proposed to describe and interpret the acoustical natural oscillation modes of the bubble, namely, the resonances. In this context, a physical model is devised in order to describe the air water interface and the implications of the high density contrast on the various regimes of the scattering resonances. The main results are presented in terms of resonance lifetime periods and quality factors. The explicit numerical calculations are undertaken through an asymptotic analysis considering typical bubble dimensions and underwater sound wavelengths. It is shown that the resonance periods are scaled according to the Minnaert’s period, which is the short lived resonance mode, called breathing mode of the bubble. As expected, resonances with longer lifetimes lead to impressive cavity quality Q-factor ranging from 1010 to 105. The present theoretical findings lead to a better understanding of the energy storage mechanism in a bubbly medium.

  18. Effects of absorption on coherence domain path length resolved dynamic light scattering in the diffuse regime

    NARCIS (Netherlands)

    Petoukhova, Anna; Steenbergen, Wiendelt; van Leeuwen, Ton; de Mul, F.F.M.


    A low coherence Mach–Zehnder interferometer is developed for path length resolved dynamic light scattering in highly turbid media. The path length distribution of multiply scatteredphotons in Intralipid is changed by the addition of absorbing dyes. Path length distributions obtained for various

  19. Random Raman lasing

    CERN Document Server

    Hokr, Brett H; Mason, John D; Beier, Hope T; Rockwll, Benjamin A; Thomas, Robert J; Noojin, Gary D; Petrov, Georgi I; Golovan, Leonid A; Yakovlev, Vladislav V


    Propagation of light in a highly scattering medium is among the most fascinating optical effect that everyone experiences on an everyday basis and possesses a number of fundamental problems which have yet to be solved. Conventional wisdom suggests that non-linear effects do not play a significant role because the diffusive nature of scattering acts to spread the intensity, dramatically weakening these effects. We demonstrate the first experimental evidence of lasing on a Raman transition in a bulk three-dimensional random media. From a practical standpoint, Raman transitions allow for spectroscopic analysis of the chemical makeup of the sample. A random Raman laser could serve as a bright Raman source allowing for remote, chemically specific, identification of powders and aerosols. Fundamentally, the first demonstration of this new light source opens up an entire new field of study into non-linear light propagation in turbid media, with the most notable application related to non-invasive biomedical imaging.

  20. Evidence of Anderson localization effects in random Raman lasing (United States)

    Hokr, Brett H.; Cerjan, Alexander; Thompson, Jonathan V.; Yuan, Luqi; Liew, Seng Fatt; Bixler, Joel N.; Noojin, Gary D.; Thomas, Robert J.; Cao, Hui; Stone, A. Douglas; Rockwell, Benjamin A.; Scully, Marlan O.; Yakovlev, Vladislav V.


    Anderson localization, also known as strong localization, is the absence of diffusion in turbid media resulting from wave interference. The effect was originally predicted for electron motion, and is widely known to exist in systems of less than 3 dimensions. However, Anderson localization of optical photons in 3 dimensional systems remains an elusive and controversial topic. Random Raman lasing offers the unique combination of large gain and virtually zero absorption. The lack of absorption makes long path length, localized modes preferred. The presence of gain offsets what little absorption is present, and preferentially amplifies localized modes due to their large Q factors compared with typical low Q modes present in complex media. Random Raman lasers exhibit several experimentally measured properties that diverge from classical, particle-like, diffusion. First, the temporal width of the emission being 1 to a few nanoseconds in duration when it is pumped with a 50 ps laser is a full order of magnitude longer than is predicted by Monte Carlo simulations. Second, the random Raman laser emission is highly multi-mode, consisting of hundreds of simultaneous lasing modes. This is in contrast to early theoretical results and back of the envelope arguments that both suggest that only a few modes should be present. We will present the evidence that suggests a divergence from classical diffusion theory. One likely explanation, that is consistent with all of these anomalies, is the presence of high-Q localized modes consistent with Anderson localization.

  1. Effect of cracking and randomness of inputs on corrosion initiation of reinforced concrete bridge decks exposed to chlorides

    Directory of Open Access Journals (Sweden)

    P. Konecny


    Full Text Available The paper is aimed at the indicative evaluation of the effect of random scatter of input parameters in case of durability of reinforced concrete bridge deck. The time to onset of corrosion of steel reinforcement of concrete bridge deck exposed to chloride is evaluated. The effect of cracking in concrete onto chloride ingress is considered. The selected steel reinforcement protection strategies are: unprotected steel reinforcement, epoxy-coated steel reinforcement and water-proof barrier bellow asphalt overlay. The preliminary model for damage effect on chloride ion ingress through water proof membrane under penetrable asphalt overlay is used. 2-D finite element chloride ingress model is combined with Monte Carlo simulation technique. The innovative crack effect modeling via highly penetrable elements is applied. Deterministic and probabilistic calculations are compared.

  2. Preference option randomized design (PORD) for comparative effectiveness research: Statistical power for testing comparative effect, preference effect, selection effect, intent-to-treat effect, and overall effect. (United States)

    Heo, Moonseong; Meissner, Paul; Litwin, Alain H; Arnsten, Julia H; McKee, M Diane; Karasz, Alison; McKinley, Paula; Rehm, Colin D; Chambers, Earle C; Yeh, Ming-Chin; Wylie-Rosett, Judith


    Comparative effectiveness research trials in real-world settings may require participants to choose between preferred intervention options. A randomized clinical trial with parallel experimental and control arms is straightforward and regarded as a gold standard design, but by design it forces and anticipates the participants to comply with a randomly assigned intervention regardless of their preference. Therefore, the randomized clinical trial may impose impractical limitations when planning comparative effectiveness research trials. To accommodate participants' preference if they are expressed, and to maintain randomization, we propose an alternative design that allows participants' preference after randomization, which we call a "preference option randomized design (PORD)". In contrast to other preference designs, which ask whether or not participants consent to the assigned intervention after randomization, the crucial feature of preference option randomized design is its unique informed consent process before randomization. Specifically, the preference option randomized design consent process informs participants that they can opt out and switch to the other intervention only if after randomization they actively express the desire to do so. Participants who do not independently express explicit alternate preference or assent to the randomly assigned intervention are considered to not have an alternate preference. In sum, preference option randomized design intends to maximize retention, minimize possibility of forced assignment for any participants, and to maintain randomization by allowing participants with no or equal preference to represent random assignments. This design scheme enables to define five effects that are interconnected with each other through common design parameters-comparative, preference, selection, intent-to-treat, and overall/as-treated-to collectively guide decision making between interventions. Statistical power functions for testing

  3. Electromagnetic scattering theory (United States)

    Bird, J. F.; Farrell, R. A.


    Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.

  4. Quantum Optical Multiple Scattering

    DEFF Research Database (Denmark)

    Ott, Johan Raunkjær

    . In the first part we use a scattering-matrix formalism combined with results from random-matrix theory to investigate the interference of quantum optical states on a multiple scattering medium. We investigate a single realization of a scattering medium thereby showing that it is possible to create entangled...... states by interference of squeezed beams. Mixing photon states on the single realization also shows that quantum interference naturally arises by interfering quantum states. We further investigate the ensemble averaged transmission properties of the quantized light and see that the induced quantum...... interference survives even after disorder averaging. The quantum interference manifests itself through increased photon correlations. Furthermore, the theoretical description of a measurement procedure is presented. In this work we relate the noise power spectrum of the total transmitted or reflected light...

  5. Effects of admittance and gyrotropy on the scattering due to chiro-ferrite medium coated microstructured PMC cylinder (United States)

    Iqbal, N.; Choudhury, P. K.


    The paper deals with scattering of electromagnetic (EM) waves by perfectly magnetic conducting (PMC) cylinder coated with chiro-ferrite medium under the assumption of oblique angle of incidence wave with perpendicular polarization (transverse electric; TE). An on-demand (in respect of orientation) kind of conducting sheath helix structure is assumed to exist at the outer surface of cylinder. The effects of sheath helix orientation, along with the material parameters, such as chirality admittance and gyrotropy, on the echo width as well as the magnitude and phase of the electric and magnetic fields are investigated. Control on the anisotropic property remains greatly useful in obtaining the required optical response from the scatterer - the feature which would find fabulous sensing related applications.

  6. Scattering Analysis of a Compact Dipole Array with Series and Parallel Feed Network including Mutual Coupling Effect

    Directory of Open Access Journals (Sweden)

    H. L. Sneha


    Full Text Available The current focus in defense arena is towards the stealth technology with an emphasis to control the radar cross-section (RCS. The scattering from the antennas mounted over the platform is of prime importance especially for a low-observable aerospace vehicle. This paper presents the analysis of the scattering cross section of a uniformly spaced linear dipole array. Two types of feed networks, that is, series and parallel feed networks, are considered. The total RCS of phased array with either kind of feed network is obtained by following the signal as it enters through the aperture and travels through the feed network. The RCS estimation of array is done including the mutual coupling effect between the dipole elements in three configurations, that is, side-by-side, collinear, and parallel-in-echelon. The results presented can be useful while designing a phased array with optimum performance towards low observability.

  7. Investigating the Effect of Adding Drug (Lidocaine) to a Drug Delivery System Using Small-Angle X-Ray Scattering (United States)

    Balogh, Joakim; Pedersen, Jan Skov

    The effect on a model drug delivery system when adding a drug, lidocaine, has been studied. Temperature and concentration dependence of a nonionic microemulsion with part of the oil, 1 and %[vol.]10, substituted with drug has been investigated. A nonionic oil-in-water microemulsion consisting of CH3(CH2)11(OCH2CH2)5OH, (C12E5), decane, water and the drug (lidocaine) that has been used to substitute part of the oil was studied. The microscopic differences have been derived from small-angle X-ray scattering (SAXS) data and the results are compared with light scattering data. Using these results together with the macroscopic differences, as observed in the phase diagram (lowering of phase boundaries), between the systems with and without lidocaine can be explained.

  8. Effect of Cross-redistribution on the Resonance Scattering Polarization of O I Line at 1302 Å (United States)

    Anusha, L. S.; Nagendra, K. N.; Uitenbroek, H.


    Oxygen is the most abundant element on the Sun after hydrogen and helium. The intensity spectrum of resonance lines of neutral oxygen, namely, O I (1302, 1305, and 1306 Å), has been studied in the literature for chromospheric diagnostics. In this paper, we study the resonance scattering polarization in the O I line at 1302 Å using two-dimensional (2D) radiative transfer in a composite atmosphere constructed using a 2D magneto-hydrodynamical snapshot in the photosphere and columns of the one-dimensional FALC atmosphere in the chromosphere. The methods developed by us recently in a series of papers to solve multi-dimensional polarized radiative transfer have been incorporated in our new code POLY2D, which we use for our analysis. We find that multi-dimensional radiative transfer including XRD effects is important in reproducing the amplitude and shape of scattering polarization signals of the O I line at 1302 Å.

  9. Dopant effects on 2-ethyl-1-hexanol: A dual-channel impedance spectroscopy and neutron scattering study (United States)

    Singh, Lokendra P.; Raihane, Ahmed; Alba-Simionesco, Christiane; Richert, Ranko


    A two-channel impedance technique has been used to study the relaxation behavior of 2-ethyl-1-hexanol with polar and non-polar dopants at the few percent concentration level over a wide temperature and frequency range. The non-polar dopants shift both the Debye and the primary structural relaxation time in the same direction, to shorter times for 3-methylpentane and to longer times for squalane, consistent with the relative glass transition temperatures (Tg) of the components. By contrast, polar dopants such as water or methanol modify the α-process towards slower dynamics and increased amplitude, while the Debye process is accelerated and with a decreased amplitude. This effect of adding water to alcohol is explained by water promoting more compact structures with reduced Kirkwood correlation factors. This picture is consistent with a shift in the neutron scattering pre-peak to lower scattering vectors and with simulation work on alcohol-water systems.

  10. Variegate galaxy cluster gas content: Mean fraction, scatter, selection effects, and covariance with X-ray luminosity (United States)

    Andreon, S.; Wang, J.; Trinchieri, G.; Moretti, A.; Serra, A. L.


    We use a cluster sample selected independently of the intracluster medium content with reliable masses to measure the mean gas mass fraction and its scatter, the biases of the X-ray selection on gas mass fraction, and the covariance between the X-ray luminosity and gas mass. The sample is formed by 34 galaxy clusters in the nearby (0.050 sample allows us to unveil a variegate population of clusters; the gas mass fraction shows a scatter of 0.17 ± 0.04 dex, possibly indicating a quite variable amount of feedback from cluster to cluster, which is larger than is found in previous samples targeting subpopulations of galaxy clusters, such as relaxed or X-ray bright clusters. The similarity of the gas density profiles induces an almost scatterless relation between X-ray luminosity, gas mass, and halo mass, and modulates selection effects in the halo gas mass fraction: gas-rich clusters are preferentially included in X-ray selected samples. The almost scatterless relation also fixes the relative scatters and slopes of the LX-M and Mgas-M relations and makes core-excised X-ray luminosities and gas masses fully covariant. Therefore, cosmological or astrophysical studies involving X-ray or SZ selected samples need to account for both selection effects and covariance of the studied quantities with X-ray luminosity/SZ strength.

  11. Critical scattering

    Energy Technology Data Exchange (ETDEWEB)

    Stirling, W.G. [Liverpool Univ., Dep. of Physics, Liverpool (United Kingdom); Perry, S.C. [Keele Univ. (United Kingdom). Dept. of Physics


    We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO{sub 3} is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs.

  12. Rainbows, supernumerary rainbows and interference effects in the angular scattering of chemical reactions: an investigation using Heisenberg's S matrix programme. (United States)

    Shan, Xiao; Xiahou, Chengkui; Connor, J N L


    In earlier research, we have demonstrated that broad "hidden" rainbows can occur in the product differential cross sections (DCSs) of state-to-state chemical reactions. Here we ask the question: can pronounced and localized rainbows, rather than broad hidden ones, occur in reactive DCSs? Further motivation comes from recent measurements by H. Pan and K. Liu, J. Phys. Chem. A, 2016, 120, 6712, of a "bulge" in a reactive DCS, which they conjecture is a rainbow. Our theoretical approach uses a "weak" version of Heisenberg's scattering matrix program (wHSMP) introduced by X. Shan and J. N. L. Connor, Phys. Chem. Chem. Phys., 2011, 13, 8392. This wHSMP uses four general physical principles for chemical reactions to suggest simple parameterized forms for the S matrix; it does not employ a potential energy surface. We use a parameterization in which the modulus of the S matrix is a smooth-step function of the total angular momentum quantum number, J, and (importantly) its phase is a cubic polynomial in J. We demonstrate for a Legendre partial wave series (PWS) the existence of pronounced rainbows, supernumerary rainbows, and other interference effects, in reactive DCSs. We find that reactive rainbows can be more complicated in their structure than the familiar rainbows of elastic scattering. We also analyse the angular scattering using Nearside-Farside (NF) PWS theory and NF PWS Local Angular Momentum (LAM) theory, including resummations of the PWS. In addition, we apply full and NF asymptotic (semiclassical) rainbow theories to the PWS - in particular, the uniform Airy and transitional Airy approximations for the farside scattering. This lets us prove that structure in the DCSs are indeed rainbows, supernumerary rainbows as well as other interference effects.

  13. Multiple and dependent scattering by densely packed discrete spheres: Comparison of radiative transfer and Maxwell theory (United States)

    Ma, L. X.; Tan, J. Y.; Zhao, J. M.; Wang, F. Q.; Wang, C. A.


    The radiative transfer equation (RTE) has been widely used to deal with multiple scattering of light by sparsely and randomly distributed discrete particles. However, for densely packed particles, the RTE becomes questionable due to strong dependent scattering effects. This paper examines the accuracy of RTE by comparing with the exact electromagnetic theory. For an imaginary spherical volume filled with randomly distributed, densely packed spheres, the RTE is solved by the Monte Carlo method combined with the Percus-Yevick hard model to consider the dependent scattering effect, while the electromagnetic calculation is based on the multi-sphere superposition T-matrix method. The Mueller matrix elements of the system with different size parameters and volume fractions of spheres are obtained using both methods. The results verify that the RTE fails to deal with the systems with a high-volume fraction due to the dependent scattering effects. Apart from the effects of forward interference scattering and coherent backscattering, the Percus-Yevick hard sphere model shows good accuracy in accounting for the far-field interference effects for medium or smaller size parameters (up to 6.964 in this study). For densely packed discrete spheres with large size parameters (equals 13.928 in this study), the improvement of dependent scattering correction tends to deteriorate. The observations indicate that caution must be taken when using RTE in dealing with the radiative transfer in dense discrete random media even though the dependent scattering correction is applied.

  14. Dynamical effects in dissociative adsorption: Quantum state-resolved studies of H(2) scattering from Pd and Cu (United States)

    Gostein, Michael

    The effects of molecular rotation and vibration in the dynamics of H2 scattering from Pd(111) and Cu(110) were studied using molecular beam and laser spectroscopy techniques. These studies test state-of-the- art theoretical simulations of molecule-surface interactions, a fundamental understanding of which is relevant to diverse fields in science and technology. Experiments on the rotational state dependence of H2 dissociation on Pd(111) were motivated by recent theoretical results concerning the concept of dynamical steering. This concept has been invoked to explain the enhancement of sticking at low translational energy for H2 incident on certain metals. It suggests that sticking should also be enhanced for low rotational energy in these systems. The experiments presented here qualitatively confirm this prediction. For incident translational energies from 31- 95 meV, the H2/Pd(111) sticking coefficient goes down as the rotational quantum number J is raised from 0 to 3. It then increases for J = 4 and 5, which is consistent with rotational energy also helping directly overcome the activation barrier. A fraction of the scattered H2 molecules are also rotationally excited. This occurs directly upon scattering but is activated by the surface temperature, not the incident translational energy. This behavior is not explained by current theoretical treatments and requires further exploration. Experiments on the vibrational state dependence of H2 scattering from Cu(110) and Pd(111) were motivated by continued considerations of activation barriers to dissociative adsorption, since vibrational energy assists in surmounting barriers which occur 'late' along the reaction path. The survival probability of H2 in the rovibrational state (v = 1, J = 1), prepared by stimulated Raman scattering, was measured for scattering from each surface. In both cases the (v = 1, J = 1) survival probability is smaller than that of the ground vibrational state, in accord with expectations for a

  15. Spin effects probed by Rayleigh X-ray scattering off hydrogenic ions

    CERN Document Server

    Safari, Laleh; Amaro, Pedro; Fratini, Filippo


    We study the polarization characteristics of x-ray photons scattered by hydrogenic atoms, based on the Dirac equation and second-order perturbation theory. The relativistic states used in calculations are obtained using the finite basis set method and expressed in terms of B-splines and B-polynomials. We derive general analytical expressions for the polarization-dependent total cross sections, which are applicable to any atom and ion, and evaluate them separately for linear and circular polarization of photons. In particular, detailed calculations are performed for the integrated Stokes parameters of the scattered light for hydrogen as well as hydrogenlike neon and argon. Analyzing such integrated Stokes parameters, special attention is given to the electron-photon spin-spin interaction, which mostly stems from the magnetic-dipole contribution of the electron-photon interaction. Subsequently, we find an energy window for the selected targets in which such spin-spin interactions can be probed.

  16. Limit on the quark-charge effective radius from inclusive ep scattering at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Turkot, Oleksii; Wichmann, Katarzyna [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zarnecki, Aleksander Filip [Faculty of Physics, University of Warsaw, Warsaw (Poland)


    The H1 and ZEUS experiments at HERA have recently presented the combined measurement of inclusive deep inelastic cross sections in neutral and charged current ep scattering corresponding to a luminosity of about 1 fb{sup -1}. The high precision of the data makes searches for new contributions to electron-quark scattering possible up to TeV scales. A new approach to beyond the Standard Model (BSM) analysis of inclusive ep data is outlined, taking into account possible contributions to the QCD fit of parton distributions coming from ''new physics'' processes. Results are presented considering a finite radius of quarks within the quark form factor model. The resulting 95% C.L. upper limit for the radius of the electroweak charge of quarks is 0.43 . 10{sup -16} cm.

  17. Wave and ray analysis of a type of cloak exhibiting magnified and shifted scattering effect


    Luo, Yu; Zhang, Jingjing; Chen, Hongsheng; Wu, Bae-Ian; Ran, Lixin; Kong, Jin Au


    Ray-tracing exercise and full-wave analysis were performed to validate the performance of a new type of cloak composed of isotropic metamaterials. It is shown that objects inside the folded region of this cloak appear invisible to the incoming light from a ray tracing exercise, but exhibit magnified and shifted scattering under a plane wave illumination from a full wave analysis. Gaussian beams are introduced to resolve this interesting paradox resulted from these two methods. We show that at...

  18. The Effects of Scattered Light from Optical Components on Visual Function (United States)


    four haze standards, four LEP of the reflective type, and one NDF. The haze standards were glass plates with particles suspended in them to yield...test and Standard Pseudoisochromatic Plates , Part 2), and no self-reported vision problems. Observers were also not taking any medications that might...collected in this study need to be accompanied by subjective data on observer ratings of scatter/haze and acceptability of the LEP for use in the cockpit

  19. Effective suppression of amplified spontaneous emission by stimulated Brillouin scattering phase conjugation (United States)

    Ni, C. K.; Kung, A. H.


    Backward stimulated Brillouin scattering was used to control the growth of amplified spontaneous emission (ASE), reducing the unwanted emission in a pulse-amplified cw Ti:sapphire laser system from 22% to less than 1 \\times 10-4 in the final output. Suppression of ASE substantially improved the spectral quality of the laser and broadened the range over which the laser is useful. The output duration was compressed, but the pulse remained nearly transform limited.

  20. Properties of cutoff corrugated surfaces for corrugated horn design. [corrugation shape and density effects on scattering (United States)

    Mentzer, C. A.; Peters, L., Jr.


    Corrugated horns involve a junction between the corrugated surface and a conducting ground plane. Proper horn design requires an understanding of the electromagnetic properties of the corrugated surface and this junction. An integral equation solution has been used to study the influence of corrugation density and tooth thickness on the power loss, surface current, and the scattering from a ground plane/corrugated surface junction.

  1. Light-scattering studies of bull spermatozoa. II. Interaction and concentration effects.


    Woolford, M.W.; Harvey, J D


    The complete autocorrelation function of the intensity fluctuations of laser light scattered from motile bull spermatozoa is shown to depend upon several factors not previously considered. Samples of bull spermatozoa generally contain a substantial proportion of dead cells, which give rise to slowly decaying components of the autocorrelation function. Whereas previous work has concentrated on the form of the fast decaying autocorrelation component, we are concerned here with the relative ampl...

  2. Multiple scattering calculation of the middle ultraviolet reaching the ground. [SST effects on ozone layer (United States)

    Shettle, E. P.; Green, A. E. S.


    An investigation is conducted regarding the increase in the UV radiation as a function of wavelength due to changes in the amounts of ozone and various other parameters affecting the radiation in the atmosphere. Attention is given to the methods that can be used to solve the problem of the transfer of radiation through an absorbing and scattering atmosphere which includes aerosols. The multiple channel solution reported by Mudgett and Richards' (1971) is extended to vertically inhomogeneous atmospheres.

  3. The Effects of Sand Sediment Volume Heterogeneities on Sound Propagation and Scattering (United States)


    OF RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 3 Attenuation in Sand Sediments Due to Scattering from Porosity Fluctuations. Brian T...sediment with porosity heterogeneities modeled using perturbation theory. The statistics of the het- erogeneities are described by exponential correlation...packing of the sand sediment, the presence of force chains should lead to het- erogeneities in the bulk moduli of the sediment. The local density

  4. Steric effects and quantum interference in the inelastic scattering of NO(X) + Ar. (United States)

    Nichols, B; Chadwick, H; Gordon, S D S; Eyles, C J; Hornung, B; Brouard, M; Alexander, M H; Aoiz, F J; Gijsbertsen, A; Stolte, S


    Rotationally inelastic collisions of NO(X) with Ar are investigated in unprecedented detail using state-to-state, crossed molecular beam experiments. The NO(X) molecules are selected in the Ω = 0.5, j = 0.5, f state and then oriented such that either the 'N' or 'O' end of the molecule is directed towards the incoming Ar atom. Velocity map ion imaging is then used to probe the scattered NO molecules in well-defined quantum states. We show that the fully quantum state-resolved differential steric asymmetry, which quantifies how the relative efficiency for scattering off the 'O' and the 'N' ends of the molecule varies with scattering angle, is strongly affected by quantum interference. Significant changes in both integral and differential cross sections are found depending on whether collisions occur with the N or O ends of the molecule. The results are well accounted for by rigorous quantum mechanical calculations, in contrast to both classical trajectory calculations and more simplistic models that provide, at best, an incomplete picture of the dynamics.

  5. Gauge invariance and relativistic effects in X-ray absorption and scattering by solids (United States)

    Bouldi, Nadejda; Brouder, Christian


    There is an incompatibility between gauge invariance and the semi-classical time-dependent perturbation theory commonly used to calculate light absorption and scattering cross-sections. There is an additional incompatibility between perturbation theory and the description of the electron dynamics by a semi-relativistic Hamiltonian. In this paper, the gauge-dependence problem of exact perturbation theory is described, the proposed solutions are reviewed and it is concluded that none of them seems fully satisfactory. The problem is finally solved by using the fully relativistic absorption and scattering cross-sections given by quantum electrodynamics. Then, a new general Foldy-Wouthuysen transformation is presented. It is applied to the many-body case to obtain correct semi-relativistic transition operators. This transformation considerably simplifies the calculation of relativistic corrections. In the process, a new light-matter interaction term emerges, called the spin-position interaction, that contributes significantly to the magnetic X-ray circular dichroism of transition metals. We compare our result with the ones obtained by using several semi-relativistic time-dependent Hamiltonians. In the case of absorption, the final formula agrees with the result obtained from one of them. However, the correct scattering cross-section is not given by any of the semi-relativistic Hamiltonians.

  6. Double-parton scattering effects in associated production of charm mesons and dijets at the LHC (United States)

    Maciuła, Rafał; Szczurek, Antoni


    We calculate several differential distributions for the production of charm and dijets. Both single-parton scattering (SPS) and double-parton scattering (DPS) contributions are calculated in the kT-factorization approach. The Kimber-Martin-Ryskin unintegrated parton distributions are used in our calculations. Relatively low cuts on jet transverse momenta are imposed to enhance the double-parton scattering mechanism contribution. We find dominance of the DPS contribution over the SPS one. We have found regions of the phase space where the SPS contribution is negligible compared to the DPS contribution. The distribution in transverse momentum of charm quark/antiquark or charmed mesons can be used to observe transition from the dominance of DPS at low transvsverse momenta to the dominance of SPS at large transverse momenta. Very distinct azimuthal correlation patterns (for c c ¯, c -jet , jet-jet, D0-jet , D0D0 ¯ ) are predicted as a result of the competition of the SPS and DPS mechanisms.

  7. Measurement of Partonic Nuclear Effects in Deep-Inelastic Neutrino Scattering using MINERvA

    CERN Document Server

    Mousseau, J; Aliaga, L; Altinok, O; Bellantoni, L; Bercellie, A; Betancourt, M; Bodek, A; Bravar, A; Budd, H; Cai, T; Carneiro, M F; Christy, M E; Chvojka, J; da Motta, H; Devan, J; Dytman, S A; Díaz, G A; Eberly, B; Felix, J; Fields, L; Fine, R; Gago, A M; Galindo, R; Gallagher, H; Ghosh, A; Golan, T; Gran, R; Harris, D A; Higuera, A; Hurtado, K; Kiveni, M; Kleykamp, J; Kordosky, M; Le, T; Maher, E; Manly, S; Mann, W A; Marshall, C M; Caicedo, D A Martinez; McFarland, K S; McGivern, C L; McGowan, A M; Messerly, B; Miller, J; Mislivec, A; Morfín, J G; Naples, D; Nelson, J K; Norrick, A; Nuruzzaman,; Osta, J; Paolone, V; Park, J; Patrick, C E; Perdue, G N; Rakotondravohitra, L; Ramirez, M A; Ransome, R D; Ray, H; Ren, L; Rimal, D; Rodrigues, P A; Ruterbories, D; Schellman, H; Schmitz, D W; Salinas, C J Solano; Tagg, N; Tice, B G; Valencia, E; Walton, T; Wolcott, J; Zavala, G; Zhang, D


    The MINERvA collaboration reports a novel study of neutrino-nucleus charged-current deep inelastic scattering (DIS) using the same neutrino beam incident on targets of polystyrene, graphite, iron, and lead. Results are presented as ratios of C, Fe, and Pb to CH. The ratios of total DIS cross sections as a function of neutrino energy and flux-integrated differential cross sections as a function of the Bjorken scaling variable x are presented in the neutrino-energy range of 5 - 50 GeV. Good agreement is found between the data and predicted ratios, based on charged-lepton nucleus scattering, at medium x and low neutrino energies. However, the data rate appears depleted in the vicinity of the nuclear shadowing region, x < 0.1. This apparent deficit, reflected in the DIS cross-section ratio at high neutrino energy , is consistent with previous MINERvA observations and with the predicted onset of nuclear shadowing with the the axial-vector current in neutrino scattering.

  8. The Inclusion of Raman Scattering Effects in the Combined Ocean-Atmosphere Radiative Transfer Model MOMO to Estimate the Influence of Raman Scattering in Case 1 Waters on Satellite Ocean Remote Sensing Applications (United States)

    von Bismarck, J.; Fischer, J.


    Raman scattering of the solar lightfield, due to energy absorption by vibrational modes of water molecules, may contribute significantly to the signals observed by remote sensing satellites over water. The inelastic fraction of the water-leaving radiance for clear water reaches values of 30% in the red part of the visible spectrum, and still reaches values of several percent in moderately turbid waters. Furthermore, inelastic scattering due to chlorophyll and yellow substance fluorescence adds to this fraction. For these reasons the inclusion of inelastic scattering sources into radiative-transfer models, used in ocean remote sensing applications or atmosphere remote sensing over the ocean, can be important. MOMO is a computer code based on the matrix-operator method designed to calculate the lightfield in the stratified atmosphere-ocean system. It has been developed at the Institute for Space Sciences of the Freie Universität Berlin and provides the full polarization state (in the newest version) and an air-sea interface accounting for radiative effects of the wind roughened water surface. The inclusion of Raman scattering effects is done by a processing module, that starts a primary MOMO program run with a high spectral resolution, to calculate the radiative energy available for inelastic scattering at each model layer boundary. The processing module then calculates the first order Raman source-terms for every observation wavelength at every layer boundary, accounting for the non-isotropicity (including the azimuthal dependence) of the Raman phase-function, the spectral redistribution, and the spectral dependence of the Raman scattering coefficient. These elementary source-terms then serve as input for the second program run, which then calculates the source-terms of all model layers, using the doubling-adding method, and the resulting radiance field. Higher orders of the Raman contribution can be computed with additional program runs. Apart from the Raman

  9. The effects of Coulomb collisions on O+, H+, and He+ plasmas for topside incoherent scatter radar applications at Jicamarca (United States)

    Milla, M. A.; Kudeki, E.; Chau, J. L.


    Coulomb collision effects on incoherent scatter radar signals become important when radar beams are pointed perpendicular to the Earth's magnetic field (B). To study these effects, Milla and Kudeki [2011] developed a procedure to estimate the spectrum of plasma density fluctuations (also known as incoherent scatter spectrum) based on simulations of collisional particle trajectories in single-ion component plasmas. In these simulations, collision effects on the particle motion are modeled using the standard Fokker-Planck model of Rosenbluth et al. [1957]. We have recently generalized the procedure of Milla and Kudeki to consider the case of multiple ion components in order to study the characteristics of the incoherent scatter spectrum in O+, H+, and He+ ionospheric plasmas, which is needed for the analysis of topside perpendicular-to-B observations at the Jicamarca Radio Observatory. In this presentation, we will report on the development of this new approach and on the characteristics of the spectrum models that were developed. The simulation results show that the ion collision process can be fairly well approximated as a Gaussian motion process, a model that has been previously studied in the literature by different authors. However, in the case of electron collisions, the process is not Gaussian having a complicated dependence on plasma parameters. As it will be discussed, electron collisions have a significant impact on the shape of the incoherent scatter spectrum. The ultimate application of the models that were developed is the simultaneous estimation of plasma drifts, densities, and temperatures of the topside equatorial ionosphere in perpendicular-to-B experiments at Jicamarca. This experimental evaluation will have a broader impact since the accuracy of the Fokker-Planck collision model will be tested. References: Milla, M. A., and E. Kudeki (2011), Incoherent scatter spectral theories-Part II: Modeling the spectrum for modes propagating perpendicular to B

  10. Periodicity-induced effects in the scattering and absorption of light by infinite and finite gratings of circular silver nanowires. (United States)

    Natarov, Denys M; Byelobrov, Volodymyr O; Sauleau, Ronan; Benson, Trevor M; Nosich, Alexander I


    We study numerically the effect of periodicity on the plasmon-assisted scattering and absorption of visible light by infinite and finite gratings of circular silver nanowires. The infinite grating is a convenient object of analysis because of the possibility to reduce the scattering problem to one period. We use the well-established method of partial separation of variables however make an important improvement by casting the resulting matrix equation to the Fredholm second-kind type, which guarantees convergence. If the silver wires have sub-wavelength radii, then two types of resonances co-exist and may lead to enhanced reflection and absorption: the plasmon-type and the grating-type. Each type is caused by different complex poles of the field function. The low-Q plasmon poles cluster near the wavelength where dielectric function equals -1. The grating-type poles make multiplets located in close proximity of Rayleigh wavelengths, tending to them if the wires get thinner. They have high Q-factors and, if excited, display intensive near-field patterns. A similar interplay between the two types of resonances takes place for finite gratings of silver wires, the sharpness of the grating-type peak getting greater for longer gratings. By tuning carefully the grating period, one can bring together two resonances and enhance the resonant scattering of light per wire by several times. © 2011 Optical Society of America

  11. Effects of repulsive three-body force in 12C + 12C scattering at 100A MeV

    Directory of Open Access Journals (Sweden)

    W.W. Qu


    Full Text Available The angular distribution of 12C + 12C scattering at an incident energy of 100A MeV has been measured. The elastic and inelastic scatterings in 12C to the excitation energies of up to ∼45 MeV were measured simultaneously for the first time with the high-resolution Grand Raiden spectrometer at the Research Center for Nuclear Physics (RCNP. The angular distributions of the elastic scattering to the ground state (01+ and inelastic scattering to the 4.44 MeV (21+ excited state were precisely obtained in the angular range of 1.0°–7.5° with a step of 0.1°. Additionally, the angular distribution was obtained for the sum of the cross sections for excitation energies above the 4.44 MeV state up to 11 MeV, which includes the 7.65 MeV (02+, 9.64 MeV (31−, and 10.30 MeV (22+ states, in addition to probably the simultaneous excitation of the 4.44 MeV state in the projectile and the target nuclei. Those combined data provide a means to study the effects of channel coupling on the elastic cross section. The observed angular distributions are compared with theoretical calculations based on three double-folding models with complex G-matrix interactions, the CEG07b, MPa, and ESC models. The importance of three-body repulsive forces included in the CEG07b and MPa models will be discussed.

  12. Modeling of high‐frequency seismic‐wave scattering and propagation using radiative transfer theory (United States)

    Zeng, Yuehua


    This is a study of the nonisotropic scattering process based on radiative transfer theory and its application to the observation of the M 4.3 aftershock recording of the 2008 Wells earthquake sequence in Nevada. Given a wide range of recording distances from 29 to 320 km, the data provide a unique opportunity to discriminate scattering models based on their distance‐dependent behaviors. First, we develop a stable numerical procedure to simulate nonisotropic scattering waves based on the 3D nonisotropic scattering theory proposed by Sato (1995). By applying the simulation method to the inversion of M 4.3 Wells aftershock recordings, we find that a nonisotropic scattering model, dominated by forward scattering, provides the best fit to the observed high‐frequency direct S waves and S‐wave coda velocity envelopes. The scattering process is governed by a Gaussian autocorrelation function, suggesting a Gaussian random heterogeneous structure for the Nevada crust. The model successfully explains the common decay of seismic coda independent of source–station locations as a result of energy leaking from multiple strong forward scattering, instead of backscattering governed by the diffusion solution at large lapse times. The model also explains the pulse‐broadening effect in the high‐frequency direct and early arriving S waves, as other studies have found, and could be very important to applications of high‐frequency wave simulation in which scattering has a strong effect. We also find that regardless of its physical implications, the isotropic scattering model provides the same effective scattering coefficient and intrinsic attenuation estimates as the forward scattering model, suggesting that the isotropic scattering model is still a viable tool for the study of seismic scattering and intrinsic attenuation coefficients in the Earth.

  13. Effects of auriculotherapy on labour pain: a randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Reginaldo Roque Mafetoni

    Full Text Available Abstract OBJECTIVE Assessing the effects of auriculotherapy in pain control and its outcomes on the duration of labour. METHOD This is a randomized, controlled, double-blind trial with preliminary data. Thirty pregnant women with gestational age ≥ 37 weeks, cervical dilatation ≥ 4 cm and two or more contractions in 10 minutes were selected and randomly divided into three groups: auriculotherapy, placebo and control. Auriculotherapy was applied using crystal beads on four strategic points. RESULTS No statistical significance was found between the groups with regard to pain; however, the women from the auriculotherapy group had lower intensity and less perception of pain at 30, 60 and 120 minutes of treatment. The average duration of labour was shorter in the auriculotherapy group (248.7 versus placebo 414.8 versus control 296.3 minutes; caesarean section rates were higher in the placebo group (50% and the same in the other groups (10%. CONCLUSION Mothers who received auriculotherapy presented a tendency for greater pain control and shorter labour duration; however, caesarean section rates in this group were similar to the control group. This trial precedes a larger study in progress. Registration of Brazilian Clinical Trials: RBR-47hhbj.

  14. Effects of professional oral health care on elderly: randomized trial. (United States)

    Morino, T; Ookawa, K; Haruta, N; Hagiwara, Y; Seki, M


    To better understand the role of the professional oral health care for elderly in improving geriatric oral health, the effects of short-term professional oral health care (once per week for 1 month) on oral microbiological parameters were assessed. Parallel, open-labelled, randomize-controlled trial was undertaken in a nursing home for elderly in Shizuoka, Japan. Thirty-four dentate elderly over 74 years were randomly assigned from ID number to the intervention (17/34) and control (17/34) groups. The outcomes were changes in oral microbiological parameters (number of bacteria in unstimulated saliva; whole bacteria, Streptococcus, Fusobacterium and Prevotella: opportunistic pathogens detection: and index of oral hygiene evaluation [Dental Plaque Index, DPI]) within the intervention period. Each parameter was evaluated at before and after intervention period. Four elderly were lost from mortality (1), bone fracture (1), refused to participate (1) and multi-antibiotics usage (1). Finally, 30 elderly were analysed (14/intervention and 16/control). At baseline, no difference was found between the control and intervention groups. After the intervention period, the percentage of Streptococcus species increased significantly in the intervention group (Intervention, 86% [12/14]; Control, 50% [8/16]: Fisher's, right-tailed, P oral health care can improve oral conditions in the elderly. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. The effectiveness of propolis on gingivitis: a randomized controlled trial. (United States)

    Bretz, Walter A; Paulino, Niraldo; Nör, Jacques E; Moreira, Alexandre


    A randomized, double-blind, controlled clinical trial was conducted to evaluate the effectiveness of a propolis rinse on induced gingivitis by using the co-twin study design. Twenty-one twin pairs (n=42) were enrolled in a gingivitis study with oral hygiene promotion (14 days) and gingivitis induction (21 days). During the gingivitis induction phase, one member of the twin pair was randomly assigned to a 2% typified propolis rinse, and the other was assigned a color-matched 0.05% sodium fluoride plus 0.05% cetylpyridinium chloride rinse (positive control). Patients rinsed twice daily with 20 mL for 30 seconds for 21 days. Gingivitis was measured on days -14 (baseline), 0 (after hygiene phase), and 21 (after no-hygiene phase) by using the Papillary Bleeding Score (PBS) and by standard digital imaging of the gum tissues (G-parameter). The 38 persons who completed the study (age 13-22 years) were well balanced according to PBS at baseline and G-parameter after the initial hygiene phase. After 21 days without oral hygiene, the propolis rinse and positive control rinse groups did not differ significantly for average PBS measurements or G-parameter. Use of a 2% typified propolis rinse was equivalent to a positive control rinse during a 21-day no-hygiene period.

  16. Applied electromagnetic scattering theory

    CERN Document Server

    Osipov, Andrey A


    Besides classical applications (radar and stealth, antennas, microwave engineering), scattering and diffraction are enabling phenomena for some emerging research fields (artificial electromagnetic materials or metamaterials, terahertz technologies, electromagnetic aspects of nano-science). This book is a tutorial for advanced students who need to study diffraction theory. The textbook gives fundamental knowledge about scattering and diffraction of electromagnetic waves and provides some working examples of solutions for practical high-frequency scattering and diffraction problems. The book focuses on the most important diffraction effects and mechanisms influencing the scattering process and describes efficient and physically justified simulation methods - physical optics (PO) and the physical theory of diffraction (PTD) - applicable in typical remote sensing scenarios. The material is presented in a comprehensible and logical form, which relates the presented results to the basic principles of electromag...

  17. Effect of electron contamination on scatter correction factors for photon beam dosimetry. (United States)

    Venselaar, J; Heukelom, S; Jager, N; Mijnheer, B; van der Laarse, R; van Gasteren, H; van Kleffens, H; Westermann, C


    Physical quantities for use in megavoltage photon beam dose calculations which are defined at the depth of maximum absorbed dose are sensitive to electron contamination and are difficult to measure and to calculate. Recently, formalisms have therefore been presented to assess the dose using collimator and phantom scatter correction factors, Sc and Sp, defined at a reference depth of 10 cm. The data can be obtained from measurements at that depth in a miniphantom and in a full scatter phantom. Equations are presented that show the relation between these quantities and corresponding quantities obtained from measurements at the depth of the dose maximum. It is shown that conversion of Sc and Sp determined at a 10 cm depth to quantities defined at the dose maximum such as (normalized) peak scatter factor, (normalized) tissue-air ratio, and vice versa is not possible without quantitative knowledge of the electron contamination. The difference in Sc at dmax resulting from this electron contamination compared with Sc values obtained at a depth of 10 cm in a miniphantom has been determined as a multiplication factor, Scel, for a number of photon beams of different accelerator types. It is shown that Scel may vary up to 5%. Because in the new formalisms output factors are defined at a reference depth of 10 cm, they do not require Scel data. The use of Sc and Sp values, defined at a 10 cm depth, combined with relative depth-dose data or tissue-phantom ratios is therefore recommended. For a transition period the use of the equations provided in this article and Scel data might be required, for instance, if treatment planning systems apply Sc data normalized at d(max).

  18. Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Botto, D.J.; Pratt, R.H.


    The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A/sup -2/ based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required.

  19. Effects of nattokinase on blood pressure: a randomized, controlled trial. (United States)

    Kim, Ji Young; Gum, Si Nae; Paik, Jean Kyung; Lim, Hyo Hee; Kim, Kyong-Chol; Ogasawara, Kazuya; Inoue, Kenichi; Park, Sungha; Jang, Yangsoo; Lee, Jong Ho


    The objective of this study was to examine the effects of nattokinase supplementation on blood pressure in subjects with pre-hypertension or stage 1 hypertension. In a randomized, double-blind, placebo-controlled trial, 86 participants ranging from 20 to 80 years of age with an initial untreated systolic blood pressure (SBP) of 130 to 159 mmHg received nattokinase (2,000 FU/capsule) or a placebo capsule for 8 weeks. Seventy-three subjects completed the protocol. Compared with the control group, the net changes in SBP and diastolic blood pressure (DBP) were -5.55 mmHg (95% confidence interval [CI], -10.5 to -0.57 mmHg; pnattokinase group compared with the control group (pnattokinase supplementation resulted in a reduction in SBP and DBP. These findings suggest that increased intake of nattokinase may play an important role in preventing and treating hypertension.

  20. Collins effect in semi-inclusive deeply inelastic scattering and in electron positron annihilation

    CERN Document Server

    Efremov, A V; Schweitzer, P


    The Collins fragmentation function is extracted from HERMES data on azimuthal single spin asymmetries in semi-inclusive deeply inelastic scattering, and BELLE data on azimuthal asymmetries in electron positron annihilations. A Gaussian model is assumed for the distribution of transverse parton momenta and predictions are used from the chiral quark-soliton model for the transversity distribution function. We find that the HERMES and BELLE data yield a consistent picture of the Collins fragmentation function which is compatible with COMPASS data and the information previously obtained from an analysis of DELPHI data. Estimates for future experiments are made.

  1. Effective suppression of amplified spontaneous emission by stimulated Brillouin scattering phase conjugation

    Energy Technology Data Exchange (ETDEWEB)

    Ni, C.K.; Kung, A.H. [Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10764 (Taiwan)


    Backward stimulated Brillouin scattering was used to control the growth of amplified spontaneous emission (ASE), reducing the unwanted emission in a pulse-amplified cw Ti:sapphire laser system from 22{percent} to less than 1{times}10{sup {minus}4} in the final output. Suppression of ASE substantially improved the spectral quality of the laser and broadened the range over which the laser is useful. The output duration was compressed, but the pulse remained nearly transform limited. {copyright} {ital 1996 Optical Society of America.}

  2. Barrier distribution from 28Si+154Sm quasielastic scattering: Coupling effects in the fusion process

    Directory of Open Access Journals (Sweden)

    Kaur Gurpreet


    Full Text Available Barrier distribution for the 28Si+154Sm system has been extracted from large angle quasielastic scattering measurement to investigate the role of various channel couplings on fusion dynamics. The coupled channel calculations, including the collective excitation of the target and projectile, are observed to reproduce the experimental BD rather well. It seems that the role of neutron transfer, relative to collective excitation, is in fact weak in the 28Si+154Sm system even though it has positive Q-value for neutron transfer channels.

  3. Electric field effects on alignment of lamellar structures in diblock copolymer thin films studied by neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiuli


    We investigated the lamellar orientation in thin films of a diblock copolymer P(S-b-MMA), under competing effects of surface interactions and an electric field applied perpendicular to the substrate. The surface effects tend to align the lamellae parallel to the substrate while the electric field tends to align the lamellae perpendicular to the substrate. Using neutron reflectivity, neutron diffuse scattering, and neutron small-angle scattering, we achieved a quantitative analysis of the internal structure of the films. Film thickness was found to play a non-trivial role in determining the structure of the films. A complete alignment by the surface effects was observed in the thinner films by annealing. The parallel orientation remains stable even if an electric field as strong as 40 V/{mu}m is applied. In the thicker films, a mixed orientation with boundary layers parallel and the central part partially perpendicular to the substrate was observed after annealing. The mixed orientation becomes unstable under a small compressive stress, and will be converted into a completely parallel orientation. The parallel orientation induced by the compressive stress remains stable as long as the electric field is weaker than several ten V/{mu}m. Only a field of about 40 V/{mu}m is able to stabilize the above mentioned mixed orientation. A fully perpendicular orientation was never observed in our experiments. Diffuse scattering shows a mosaic structure in the absence of an electric field, whose mosaicity will be increased by the torque exerted by an electric field. The lateral correlation length of the lamellar domains is estimated as 1-2 {mu}m. Limited by the small q{sub x}-range we have used, a clear statement on the existence of the electric-field-induced structural undulations predicted by the Onuki's theory cannot be made from our experiments. (orig.)

  4. Scaling of the anomalous Hall effect in epitaxial antiperovskite Mn3.5Dy0.5N involving multiple competing scattering mechanisms (United States)

    Meng, M.; Wu, S. X.; Zhou, W. Q.; Li, S. W.


    Anomalous Hall effect (AHE) has been studied for ferrimagnetic antiperovskite Mn3.5Dy0.5N film grown by molecular-beam epitaxy. Reflective high energy electron diffraction and transmission electron microscopy demonstrate the high quality of the film. We have used a scaling involving multiple competing scattering mechanisms to distinguish variations of contributions to the AHE by heavily doped Dy. The scaling analysis revealed that the heavily doped Dy has dramatically modified the skew scattering part of the AHE in Mn4N and Mn3.5Dy0.5N has a totally different scattering mechanism from an undoped film.

  5. Same-sign WW scattering at the LHC: can we discover BSM effects before discovering new states?

    Energy Technology Data Exchange (ETDEWEB)

    Kalinowski, Jan [Warsaw U.; Kozów, Paweł [Warsaw U.; Pokorski, Stefan [Warsaw U.; Rosiek, Janusz [Warsaw U.; Szleper, Michał [NCBJ, Swierk; Tkaczyk, Sławomir [Fermilab


    It is possible that measurements of vector boson scattering (VBS) at the LHC will reveal disagreement with Standard Model predictions, but no new particles will be observed directly. The task is then to learn as much as possible about the new physics from a VBS analysis carried within the framework of the Effective Field Theory (EFT). In this paper we discuss issues related to the correct usage of the EFT when the WW invariant mass is not directly accessible experimentally, as in purely leptonic W decay channels. The strategies for future data analyses in case such scenario indeed occurs are proposed.

  6. Thomson scattering from a three-component plasma. (United States)

    Johnson, W R; Nilsen, J


    A model for a three-component plasma consisting of two distinct ionic species and electrons is developed and applied to study x-ray Thomson scattering. Ions of a specific type are assumed to be identical and are treated in the average-atom approximation. Given the plasma temperature and density, the model predicts mass densities, effective ionic charges, and cell volumes for each ionic type, together with the plasma chemical potential and free-electron density. Additionally, the average-atom treatment of individual ions provides a quantum-mechanical description of bound and continuum electrons. The model is used to obtain parameters needed to determine the dynamic structure factors for x-ray Thomson scattering from a three-component plasma. The contribution from inelastic scattering by free electrons is evaluated in the random-phase approximation. The contribution from inelastic scattering by bound electrons is evaluated using the bound-state and scattering wave functions obtained from the average-atom calculations. Finally, the partial static structure factors for elastic scattering by ions are evaluated using a two-component version of the Ornstein-Zernike equations with hypernetted chain closure, in which electron-ion interactions are accounted for using screened ion-ion interaction potentials. The model is used to predict the x-ray Thomson scattering spectrum from a CH plasma and the resulting spectrum is compared with experimental results obtained by Feltcher et al. [Phys. Plasmas 20, 056316 (2013)].

  7. Effect of etanercept in polymyalgia rheumatica: a randomized controlled trial (United States)


    Introduction To elucidate in polymyalgia rheumatica (PMR) the role of tumor necrosis factor (TNF) α and the therapeutic potential of blockade with soluble TNF-α receptor, we carried out the first randomized controlled trial with etanercept in PMR. Methods Twenty newly diagnosed, glucocorticoid (GC) naïve patients with PMR and 20 matched non-PMR control subjects completed the trial. Subjects were randomized in a 1:1 ratio to monotherapy with etanercept (25 mg s.c. biweekly) or placebo (saline) for 14 days. Study outcomes were assessed at baseline and after 14 days. The primary outcome was the change in PMR activity score (PMR-AS). Secondary outcomes were: changes in erythrocyte sedimentation rate (ESR) and plasma levels of TNF-α and interleukin (IL) 6; patients' functional status (health assessment questionnaire) and cumulative tramadol intake during the trial. Results At baseline, plasma TNF-α was higher in patients than in controls (P etanercept treatment (P etanercept decreased PMR-AS by 24% (P = 0.011), reflecting significant improvements in shoulder mobility, physician's global assessment and C-reactive protein, and insignificant (P > 0.05) improvements in duration of morning stiffness and patient's assessment of pain. In parallel, ESR and IL-6 were reduced (P 0.05). Functional status did not change and tramadol intake did not differ between patient groups. In controls, no changes occurred in both groups. Conclusions Etanercept monotherapy ameliorates disease activity in GC naïve patients with PMR. However, the effect is modest, indicating a minor role of TNF-α in PMR. Trial registration (NCT00524381). PMID:20854662

  8. The effects of automated scatter feeders on captive grizzly bear activity budgets. (United States)

    Andrews, Nathan L P; Ha, James C


    Although captive bears are popular zoo attractions, they are known to exhibit high levels of repetitive behaviors (RBs). These behaviors have also made them particularly popular subjects for welfare research. To date, most research on ursid welfare has focused on various feeding methods that seek to increase time spent searching for, extracting, or consuming food. Prior research indicates an average of a 50% reduction in RBs when attempts are successful and, roughly, a 50% success rate across studies. This research focused on decreasing time spent in an RB while increasing the time spent active by increasing time spent searching for, extracting, and consuming food. The utility of timed, automated scatter feeders was examined for use with captive grizzly bears (Ursis arctos horribilis). Findings include a significant decrease in time spent in RB and a significant increase in time spent active while the feeders were in use. Further, the bears exhibited a wider range of behaviors and a greater use of their enclosure.

  9. Structure dependence of final-state effects in deep inelastic neutron scattering: Quasiclassical theory

    Energy Technology Data Exchange (ETDEWEB)

    Silver, R.N.; Reiter, G.


    Using a quasiclassical approximation, we calculate the Q..-->..infinity limit of S(Q, for finite potentials with a hard core. For yequivalentm( 2//2m)/h-dash-barQ, we find QS(Q, equals a convolution of the impulse-approximation result F/sub IA/(y) with a ''final-state'' resolution function, R/sub FS/(y), which depends on the structure of the material through the radial distribution function g(r). For realistic g(r), R/sub FS/(y) has smaller full width at half maximum than the Hohenberg-Platzman prediction, zero second moment, and no Lorentzian wings. We compare with previous theoretical work, and we discuss the determination of momentum distributions in quantum solids and fluids from deep-inelastic neutron scattering data.

  10. Polarization effects in reactive scattering of Na atoms in the 4D level

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, P.S.; Covinsky, M.H.; Schmidt, H.; Balko, B.A.; Lee, Y.T.; Mestdagh, J.M.


    Experiments performed using a crossed beam apparatus have shown that the reactivity of Na(4D) with HCl and O/sub 2/ changes substantially as the 4d orbital alignment is varied. This change is found different for the two reactions. The favorable alignment for the reaction with HCl has the d orbital aligned along the relative velocity vector of the reactants. This result is consistent with a long range electron transfer initiating the reaction and suggests that the Na-Cl axis dominates over the H-Cl axis in determining the favorable atomic orbital alignment. For the reaction with O/sub 2/, the NaO formation has a high translational energy threshold, and the favored orbital alignment varies as a function of the NaO laboratory scattering angle. Very restricted conditions are found to be necessary for the reaction: Near collinear geometry and the d orbital perpendicular to the molecular axis.

  11. Polarization effects in reactive scattering of Na atoms in the 4 D level (United States)

    Weiss, P. S.; Covinsky, M. H.; Schmidt, H.; Balko, B. A.; Lee, Y. T.; Mestdagh, J. M.


    Experiments performed using a crossed beam apparatus have shown that the reactivity of Na(4 D) with HCl and O2 changes substantially as the 4 d orbital alignment is varied. This change is found to be different for the two reactions. The favorable alignment for the reaction with HCl has the d orbital aligned along the relative velocity vector of the reactants. This result is consistent with a long range electron transfer initiating the reaction and suggests that the Na-Cl axis dominates over the H-Cl axis in determining the favorable atomic orbital alignment. For the reaction with O2, the NaO formation has a high translational energy threshold, and the favored orbital alignment varies as a function of the NaO laboratory scattering angle. Very restricted conditions are found to be necessary for the reaction: near collinear geometry and the d orbital perpendicular to the molecular axis.

  12. Disorder effects on the static scattering function of star branched polymers

    Directory of Open Access Journals (Sweden)

    V. Blavatska


    Full Text Available We present an analysis of the impact of structural disorder on the static scattering function of f-armed star branched polymers in d dimensions. To this end, we consider the model of a star polymer immersed in a good solvent in the presence of structural defects, correlated at large distances r according to a power law ~r-a. In particular, we are interested in the ratio g(f of the radii of gyration of star and linear polymers of the same molecular weight, which is a universal experimentally measurable quantity. We apply a direct polymer renormalization approach and evaluate the results within the double ϵ = 4 - d, δ = 4 - a-expansion. We find an increase of g(f with an increasing δ. Therefore, an increase of disorder correlations leads to an increase of the size measure of a star relative to linear polymers of the same molecular weight.

  13. Observational appearance and spectrum of black hole winds from supercritical accretion discs: scattering effect (United States)

    Orihashi, M.; Fukue, J.


    We investigate the observational appearance of a black hole wind blown off from a supercritical accretion disc, considering the electron scattering, which separates the thermalization surface and the apparent photosphere, especially in the high-energy regime. Similar to the spherical case, the size of the thermalization surface becomes quite smaller than that of the apparent photosphere. In contrast with the spherical case, the shapes of the thermalization surface as well as the apparent photosphere are extremely aspherical. As a result, the expected spectral energy distribution is somewhat flat and soft in the middle and high-energy regimes, except for a small peak of the outer disc origin in the low-energy regime.

  14. Optimizing Neutron Thermal Scattering Effects in very High Temperature Reactors. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Hawari, Ayman [North Carolina State Univ., Raleigh, NC (United States). Dept. of Nuclear Engineering; Ougouag, Abderrafi [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    This project aims to develop a holistic understanding of the phenomenon of neutron thermalization in the VHTR. Neutron thermalization is dependent on the type and structure of the moderating material. The fact that the moderator (and reflector) in the VHTR is a solid material will introduce new and interesting considerations that do not apply in other (e.g. light water) reactors. The moderator structure is expected to undergo radiation induced changes as the irradiation (or burnup) history progresses. In this case, the induced changes in structure will have a direct impact on many properties including the neutronic behavior. This can be easily anticipated if one recognizes the dependence of neutron thermalization on the scattering law of the moderator. For the pebble bed reactor, it is anticipated that the moderating behavior can be tailored, e.g. using moderators that consist of composite materials, which could allow improved optimization of the moderator-to-fuel ratio.

  15. Neutron-proton scattering at next-to-next-to-leading order in Nuclear Lattice Effective Field Theory

    Energy Technology Data Exchange (ETDEWEB)

    Alarcon, Jose Manuel [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Thomas Jefferson National Accelerator Facility, Theory Center, Newport News, VA (United States); Du, Dechuan; Laehde, Timo A.; Li, Ning; Lu, Bing-Nan; Luu, Thomas [Institute for Advanced Simulation, Institut fuer Kernphysik, and Juelich Center for Hadron Physics, Forschungszentrum Juelich, Juelich (Germany); Klein, Nico [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Lee, Dean [North Carolina State University, Department of Physics, Raleigh, NC (United States); Meissner, Ulf G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Institute for Advanced Simulation, Institut fuer Kernphysik, and Juelich Center for Hadron Physics, Forschungszentrum Juelich, Juelich (Germany); Forschungszentrum Juelich, JARA - High Performance Computing, Juelich (Germany)


    We present a systematic study of neutron-proton scattering in Nuclear Lattice Effective Field Theory (NLEFT), in terms of the computationally efficient radial Hamiltonian method. Our leading-order (LO) interaction consists of smeared, local contact terms and static one-pion exchange. We show results for a fully non-perturbative analysis up to next-to-next-to-leading order (NNLO), followed by a perturbative treatment of contributions beyond LO. The latter analysis anticipates practical Monte Carlo simulations of heavier nuclei. We explore how our results depend on the lattice spacing a, and estimate sources of uncertainty in the determination of the low-energy constants of the next-to-leading-order (NLO) two-nucleon force. We give results for lattice spacings ranging from a = 1.97 fm down to a = 0.98 fm, and discuss the effects of lattice artifacts on the scattering observables. At a = 0.98 fm, lattice artifacts appear small, and our NNLO results agree well with the Nijmegen partial-wave analysis for S-wave and P-wave channels. We expect the peripheral partial waves to be equally well described once the lattice momenta in the pion-nucleon coupling are taken to coincide with the continuum dispersion relation, and higher-order (N3LO) contributions are included. We stress that for center-of-mass momenta below 100 MeV, the physics of the two-nucleon system is independent of the lattice spacing. (orig.)

  16. Longitudinal asymmetry and proton spin rotation in p ⃗d scattering with pionless effective field theory (United States)

    Mahboubi, N.; Bayegan, S.; Nematollahi, H.; Arani, M. Moeini


    The energy dependence of the longitudinal asymmetry (AL) and the spin rotation of the proton on the deuterium target in the p ⃗d scattering are presented using the pionless effective field theory formalism. The strong, weak, and Coulomb interactions have been introduced in the p ⃗d scattering. We have shown that in the presence of Coulomb interaction, the parity-conserving (PC) and the parity-violating (PV) sectors are modified. The PV two-body transitions diagrams have been evaluated with the inclusion of Coulomb interaction and consequently the PV observables are enhanced. The leading-order values of the AL and the spin rotation of the proton on the deuterium target are calculated at the proton laboratory energies above 0.7 MeV, in order to calculate the Coulomb effect perturbatively, up to 3 MeV where typical momenta is Q ≪mπ . With the lack of experimental data for the low-energy coupling constants (LECs), we have used two estimated sets for the five independent (PV) LECs of the weak N N PV Lagrangian. The order of magnitude, of the PV observables with these two sets, is found to be 10-6 to 10-7 which indicates that the expected order is achieved in this energy range. The cutoff independent results support the validity of our approach.

  17. Theory of magnetic surface anisotropy and exchange effects in the Brillouin scattering of light by magnetostatic spin waves (invited) (United States)

    Rado, G. T.; Hicken, R. J.


    A new theory of the Brillouin shift in the inelastic scattering of light by magnetostatic spin waves is presented. Contrary to previous work, the present calculations do include exchange effects and treat the magnetic surface anisotropy constants Ks and Kss directly rather than via the stratagem of effective volume anisotropies. The experimental data for {110} Fe on W are explained about as well by the present theory as by previous work. A detailed analysis reveals the previously unnoticed fact that the signs of Ks and Kss for (1¯10) Fe on W are opposite to those for (1¯10) Fe on GaAs. Some new spin-wave modes arising from exchange are predicted and shown to occur outside the frequency range which has been investigated experimentally. A quantitative explanation is proposed for the occasional applicability of a theory based on effective volume anisotropies and zero exchange.

  18. Investigation of hygroscopic growth effect on aerosol scattering coefficient at a rural site in the southern North China Plain. (United States)

    Wu, Yunfei; Wang, Xiaojia; Yan, Peng; Zhang, Leiming; Tao, Jun; Liu, Xinyu; Tian, Ping; Han, Zhiwei; Zhang, Renjian


    Aerosol optical properties and the effect of hygroscopic growth on the scattering coefficients at a rural site in the southern North China Plain were investigated based on a two-month observation conducted in the summer of 2014. The scattering coefficient of dry aerosols was high, with a mean (±standard deviation) of 338.8±209.9Mm-1 (520nm) during the observation period. A noticeable enhancement in aerosol scattering due to hygroscopic growth was observed, e.g., by a factor of 2.28±0.69 at RH of 80% (referred to as f(RH=80%)) and 3.39±1.14 at RH of 85% (f(RH=85%)). The high content of water-soluble secondary inorganic aerosols (SIAs), accounting for 53.1% of fine particulate matter (i.e., PM2.5) on average, was mainly responsible for the high hygroscopicity. f(RH=80%) increased with increasing SIA mass fraction in PM2.5. This was especially the case when SIAs were mainly in finer particulate matter, i.e., PM1. A number of considerably low f(RH=80%) values was observed due to relatively low mass fraction of SIAs in PM1 despite high fraction in PM2.5. Particle size distributions, especially those of SIAs, also played a remarkable role in the hygroscopicity of ambient aerosols. No significant difference in hygroscopicity was found between different pollution episodes due to the dominance of SIAs in all the cases. Slightly higher hygroscopic growth factors were observed during the clean episode, which were attributed to the smaller particle sizes. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Detecting scattered light from low-mass molecular cores at 3.6 μm. Impact of global effects on the observation of coreshine (United States)

    Steinacker, J.; Andersen, M.; Thi, W.-F.; Bacmann, A.


    Context. Recently discovered scattered light at 3-5 μm from low-mass cores (so-called "coreshine") reveals the presence of grains around 1 μm, which is larger than the grains found in the low-density interstellar medium. But only about half of the 100+ cores investigated so far show the effect. This prompts further studies on the origin of this detection rate. Aims: We aim to supply criteria for detecting scattered light at 3.6 μm from molecular cloud cores. Methods: From the 3D continuum radiative transfer equation, we derive the expected scattered light intensity from a core placed in an arbitrary direction seen from Earth. We use the approximation of single scattering, consider extinction up to 2nd-order Taylor approximation, and neglect spatial gradients in the dust size distribution. We analyze how scattered light can outshine the absorbing effect of extinction in front of background radiation by the core for given grain properties, anisotropic interstellar radiation field and background field. The impact of the directional characteristics of the scattering on the detection of scattered light from cores is calculated for a given grain size distribution, and local effects like additional radiation field components are discussed. The surface brightness profiles of a core with a 1D density profile are calculated for various Galactic locations, and the results are compared to the approximate detection limits. Results: We find that for optically thin radiation and a constant size distribution, a simple limit for detecting scattered light from a low-mass core can be derived that holds for grains with sizes smaller than 0.5 μm. The extinction by the core prohibits detection in bright parts of the Galactic plane, especially near the Galactic center. For scattered light received from low-mass cores with grain sizes beyond 0.5 μm, the directional characteristics of the scattering favors the detection of scattered light above and below the Galactic center, and to

  20. Application of a folding-model optical potential to analyzing inelastic pion–nucleus scattering and the in-medium effect on a pion–nucleon amplitude

    Energy Technology Data Exchange (ETDEWEB)

    Lukyanov, V. K., E-mail:; Zemlyanaya, E. V.; Lukyanov, K. V. [Joint Institute for Nuclear Research (Russian Federation); Abdul-Magead, I. A. M. [Cairo University (Egypt)


    The folding-model optical potential is generalized in such a way as to apply it to calculating the cross sections for inelastic scattering of π{sup ±}-mesons on {sup 28}Si, {sup 40}Ca, {sup 58}Ni, and {sup 208}Pb nuclei at the energies of 162, 180, 226, and 291 MeV leading to the excitation of the 2{sup +} and 3{sup −} collective states. In doing this, use is made of known nucleon-density distributions in nuclei and the pion–nucleon scattering amplitude whose parameters were obtained previously by fitting the elastic scattering cross sections for the same nuclei. Thus, the values of quadrupole (β{sub 2}) and octupole (β{sub 3}) deformations of nuclei appear here as the only adjustable parameters. The scattering cross section is calculated by solving the relativistic wave equation, whereby effects of relativization and distortion in the entrance and exit scattering channels are taken exactly into account. The cross sections calculated in this way for inelastic scattering are in good agreement with respective experimental data. The importance of the inclusion of in-medium effects in choosing parameters of the pion–nucleon amplitude is emphasized.

  1. Scattering theory

    CERN Document Server

    Friedrich, Harald


    This corrected and updated second edition of "Scattering Theory" presents a concise and modern coverage of the subject. In the present treatment, special attention is given to the role played by the long-range behaviour of the projectile-target interaction, and a theory is developed, which is well suited to describe near-threshold bound and continuum states in realistic binary systems such as diatomic molecules or molecular ions. It is motivated by the fact that experimental advances have shifted and broadened the scope of applications where concepts from scattering theory are used, e.g. to the field of ultracold atoms and molecules, which has been experiencing enormous growth in recent years, largely triggered by the successful realization of Bose-Einstein condensates of dilute atomic gases in 1995. The book contains sections on special topics such as near-threshold quantization, quantum reflection, Feshbach resonances and the quantum description of scattering in two dimensions. The level of abstraction is k...

  2. Sequential methods for random-effects meta-analysis (United States)

    Higgins, Julian P T; Whitehead, Anne; Simmonds, Mark


    Although meta-analyses are typically viewed as retrospective activities, they are increasingly being applied prospectively to provide up-to-date evidence on specific research questions. When meta-analyses are updated account should be taken of the possibility of false-positive findings due to repeated significance tests. We discuss the use of sequential methods for meta-analyses that incorporate random effects to allow for heterogeneity across studies. We propose a method that uses an approximate semi-Bayes procedure to update evidence on the among-study variance, starting with an informative prior distribution that might be based on findings from previous meta-analyses. We compare our methods with other approaches, including the traditional method of cumulative meta-analysis, in a simulation study and observe that it has Type I and Type II error rates close to the nominal level. We illustrate the method using an example in the treatment of bleeding peptic ulcers. Copyright © 2010 John Wiley & Sons, Ltd. PMID:21472757

  3. Effect of macromolecular impurities on lysozyme solubility and crystallizability: dynamic light scattering, phase diagram, and crystal growth studies (United States)

    Skouri, M.; Lorber, B.; Giegé, R.; Munch, J.-P.; Candau, J. S.


    The effects of macromolecular impurities on protein solubility and crystallizability were investigated by dynamic light scattering and crystal growth experiments using hen egg-white lysozyme as the model protein. In the presence of traces of protein impurities, representing no more than 2% (w/w) of the total protein, the average diffusion coefficients of the macromolecular particles found in undersaturated lysozyme solutions are significantly lower than those measured with purest lysozyme preparations. This fact is explained by the simultaneous existence of individual molecules and of large size aggregates in contaminated solutions, as indicated by the bimodal light scattering autocorrelation function. Controlled contamination experiments in which ovalbumin or conalbumin were added to purest lysozyme indicate that aggregates result from heterogeneous association of lysozyme molecules with the structurally unrelated proteins. These aggregates might become starting points for heterogeneous nucleation leading to the growth of ill-shaped microcrystals. Aggregates in under- or supersaturated lysozyme solutions containing NaCl can be eliminated by filtration over microporous membranes. As a result the number of ill-shaped crystals diminishes drastically; that of well-shaped tetragonal crystals decreases also but their size increases.

  4. Facile synthesis of AgCl/polydopamine/Ag nanoparticles with in-situ laser improving Raman scattering effect

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan; Zhang, Wenqi; Wang, Lin; Wang, Feng, E-mail:; Yang, Haifeng


    Highlights: • AgCl/PDA/AgNPs (polydopamine (PDA) adlayer covered cubic AgCl core inlaid with Ag nanoparticles (AgNPs)) was fabricated for in-situ SERS detection. • Such SERS substrate shows in-situ laser improving Raman scattering effect due to the generation of more AgNPs. • Enhancement factor could reach 10{sup 7}. • Such SERS substrate shows good reproducibility and long term stability. - Abstract: We reported a simple and fast method to prepare a composite material of polydopamine (PDA) adlayer covered cubic AgCl core, which was inlaid with Ag nanoparticles (NPs), shortly named as AgCl/PDA/AgNPs. The resultant AgCl/PDA/AgNPs could be employed as surface-enhanced Raman scattering (SERS) substrate for in-situ detection and the SERS activity could be further greatly improved due to the production of more AgNPs upon laser irradiation. With 4-mercaptopyridine (4-Mpy) as the probe molecule, the enhancement factor could reach 10{sup 7}. Additionally, such SERS substrate shows good reproducibility with relative standard deviation of 7.32% and long term stability (after storage for 100 days under ambient condition, SERS intensity decay is less than 25%). In-situ elevating SERS activity of AgCl/PDA/AgNPs induced by laser may be beneficial to sensitive analysis in practical fields.

  5. Effects of auriculotherapy on labour pain: a randomized clinical trial. (United States)

    Mafetoni, Reginaldo Roque; Shimo, Antonieta Keiko Kakuda


    Assessing the effects of auriculotherapy in pain control and its outcomes on the duration of labour. This is a randomized, controlled, double-blind trial with preliminary data. Thirty pregnant women with gestational age ≥ 37 weeks, cervical dilatation ≥ 4 cm and two or more contractions in 10 minutes were selected and randomly divided into three groups: auriculotherapy, placebo and control. Auriculotherapy was applied using crystal beads on four strategic points. No statistical significance was found between the groups with regard to pain; however, the women from the auriculotherapy group had lower intensity and less perception of pain at 30, 60 and 120 minutes of treatment. The average duration of labour was shorter in the auriculotherapy group (248.7 versus placebo 414.8 versus control 296.3 minutes); caesarean section rates were higher in the placebo group (50%) and the same in the other groups (10%). Mothers who received auriculotherapy presented a tendency for greater pain control and shorter labour duration; however, caesarean section rates in this group were similar to the control group. This trial precedes a larger study in progress. Registration of Brazilian Clinical Trials: RBR-47hhbj. Avaliar os efeitos da auriculoterapia no controle da dor e seus desfechos na duração do trabalho de parto. Trata-se de um ensaio controlado, randomizado e duplo-cego, com dados preliminares. Foram selecionadas 30 parturientes com idade gestacional ≥ 37 semanas, dilatação cervical ≥ 4 cm e duas ou mais contrações em 10 minutos, divididas aleatoriamente em três grupos: auriculoterapia, placebo ou controle. A auriculoterapia foi aplicada com microesferas de cristais em quatro pontos estratégicos. Não houve significância estatística entre os grupos com relação à dor; no entanto, as mulheres do grupo de auriculoterapia, apresentaram menor intensidade e menor percepção da dor aos 30, 60 e 120 minutos do tratamento. A média de duração do trabalho de

  6. Effectiveness of myofascial release: systematic review of randomized controlled trials. (United States)

    Ajimsha, M S; Al-Mudahka, Noora R; Al-Madzhar, J A


    Myofascial release (MFR) is a form of manual therapy that involves the application of a low load, long duration stretch to the myofascial complex, intended to restore optimal length, decrease pain, and improve function. Anecdotal evidence shows great promise for MFR as a treatment for various conditions. However, research to support the anecdotal evidence is lacking. To critically analyze published randomized controlled trials (RCTs) to determine the effectiveness of MFR as a treatment option for different conditions. Electronic databases: MEDLINE, CINAHL, Academic Search Premier, Cochrane library, and Physiotherapy Evidence Database (PEDro), with key words myofascial release and myofascial release therapy. No date limitations were applied to the searches. Articles were selected based upon the use of the term myofascial release in the abstract or key words. The final selection was made by applying the inclusion and exclusion criteria to the full text. Studies were included if they were English-language, peer-reviewed RCTs on MFR for various conditions and pain. Data collected were number of participants, condition being treated, treatment used, control group, outcome measures and results. Studies were analyzed using the PEDro scale and the Center for Evidence-Based Medicine's Levels of Evidence scale. The literature regarding the effectiveness of MFR was mixed in both quality and results. Although the quality of the RCT studies varied greatly, the result of the studies was encouraging, particularly with the recently published studies. MFR is emerging as a strategy with a solid evidence base and tremendous potential. The studies in this review may help as a respectable base for the future trials. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. A Grazing-Incidence Small-Angle X-Ray Scattering View of Vertically Aligned ZnO Nanowires

    Directory of Open Access Journals (Sweden)

    M. Lučić Lavčević


    Full Text Available We report a grazing-incidence small-angle X-ray scattering study of ZnO films with vertically aligned and randomly distributed nanowires, grown through a hydrothermal growth process on nanostructured ZnO seeding coatings and deposited by electron beam evaporation on silicon and glass, respectively. The comparison of the scattering patterns of seeding coatings and nanowires showed that the scattering of vertically aligned nanowires exhibited a specific feature: the dominant characteristic of their scattering patterns is the appearance of fine structure effects around the specular peak. These effects were clarified by the combined reflection and scattering phenomena, suggested for the aligned nanowires-substrate system. Furthermore, they enabled the calculation of the average gyration radius of nanowires in horizontal direction. The calculated value was in good agreement with the radii of nanowires estimated by surface electron microscopy. Therefore, the observed feature in the scattering pattern can serve as evidence of the aligned growth of nanowires.

  8. Randomized trial testing the effect of peer education at increasing fruit and vegetable intake

    National Research Council Canada - National Science Library

    Buller, D B; Morrill, C; Taren, D; Aickin, M; Sennott-Miller, L; Buller, M K; Larkey, L; Alatorre, C; Wentzel, T M


    .... In a randomized trial, peer education was tested for effectiveness at increasing fruit and vegetable intake among lower socioeconomic, multicultural labor and trades employees. Employees (n = 2091...

  9. Surfactant size effect on surface-enhanced Raman scattering intensity from silver nanoparticles. (United States)

    Bae, Doo Ri; Chang, Sung-Jin; Huh, Yun Suk; Han, Young-Kyu; Lee, You-Jin; Yi, Gi-Ra; Kim, Soohyun; Lee, Gaehang


    We report on the synthesis of two types of Ag nanoparticles (NPs) and the influence of adsorbed surfactant size on the NP surface for surface-enhanced Raman scattering (SERS) signals. Both particles were of similar size and morphology but were covered by surfactants of different sizes; one surfactant was sodium citrate (molecular weight: 258) and the other was sodium polyacrylate (molecular weight: 2100). For SERS measurement, 4-mecapobenzoic acid and 4-naphthalene thiol as Raman-active dyes were immobilized on the surface of each AgNP. The signals from Raman-active dyes on AgNPs covered with citrate displayed 10 times higher intensity than those from polyacrylate-stabilized AgNPs. Elemental analysis (EA) revealed that the average weight percentage of sulfur is 0.94 wt% and 0.12 wt% for citrate-stabilized and polyacrylate-stabilized AgNPs, respectively. The sulfur content difference was attributed to the size of the existing surfactant influencing the ligand exchange by steric hindrance and subsequently the amount of sulfur content of the particles. These experimental results suggest that the size of initial surfactant should be taken into account when synthesizing a metal particle for enhancing SERS signal.

  10. Hip-Hop to Health Jr. Randomized Effectiveness Trial (United States)

    Kong, Angela; Buscemi, Joanna; Stolley, Melinda R.; Schiffer, Linda A.; Kim, Yoonsang; Braunschweig, Carol L.; Gomez-Perez, Sandra L.; Blumstein, Lara B.; Van Horn, Linda; Dyer, Alan R.; Fitzgibbon, Marian L.


    Introduction The preschool years provide a unique window of opportunity to intervene on obesity-related lifestyle risk factors during the formative years of a child’s life. The purpose of this study was to assess the impact of a preschool-based obesity prevention effectiveness trial at 1-year follow-up. Design RCT. Settings/participants Primarily African American children (aged 3–5 years, N=618) attending Head Start preschool programs administered by Chicago Public Schools. Methods Eighteen preschools were randomly assigned in 2007–2008 to receive either: (1) a 14-week teacher-delivered intervention focused on healthy lifestyle behaviors; or (2) a 14-week teacher-delivered general health curriculum (control group). Main outcome measures The primary outcome, BMI, was measured at baseline, post-intervention, and 1-year follow-up. Diet and screen time behaviors were also assessed at these time points. Multilevel mixed effects models were used to test for between-group differences. Data were analyzed in 2014. Results Significant between-group differences were observed in diet, but not in BMI z-score or screen time at 1-year follow-up. Diet differences favored the intervention arm over controls in overall diet quality (p=0.02) and in subcomponents of diet quality, as measured by the Healthy Eating Index-2005, and in fruit intake (servings/day, excludes juice) (p=0.02). Diet quality worsened more among controls than the intervention group at 1-year follow-up. Conclusions The adaptation of Hip-Hop to Health Jr. produced modest benefits in diet quality, but did not significantly impact weight gain trajectory. Not unlike other effectiveness trials, this real-world version delivered by Head Start teachers produced fewer benefits than the more rigorous efficacy trial. It is important to understand and build upon the lessons learned from these types of trials so that we can design, implement, and disseminate successful evidence-based programs more widely and effectively

  11. Effect of etanercept in polymyalgia rheumatica: a randomized controlled trial

    DEFF Research Database (Denmark)

    Kreiner, Frederik; Galbo, Henrik


    To elucidate in polymyalgia rheumatica (PMR) the role of tumor necrosis factor (TNF) a and the therapeutic potential of blockade with soluble TNF-a receptor, we carried out the first randomized controlled trial with etanercept in PMR.......To elucidate in polymyalgia rheumatica (PMR) the role of tumor necrosis factor (TNF) a and the therapeutic potential of blockade with soluble TNF-a receptor, we carried out the first randomized controlled trial with etanercept in PMR....

  12. Effect of etanercept in polymyalgia rheumatica: a randomized controlled trial

    DEFF Research Database (Denmark)

    Kreiner, Frederik; Galbo, Henrik


    To elucidate in polymyalgia rheumatica (PMR) the role of tumor necrosis factor (TNF) α and the therapeutic potential of blockade with soluble TNF-α receptor, we carried out the first randomized controlled trial with etanercept in PMR.......To elucidate in polymyalgia rheumatica (PMR) the role of tumor necrosis factor (TNF) α and the therapeutic potential of blockade with soluble TNF-α receptor, we carried out the first randomized controlled trial with etanercept in PMR....

  13. Scattering from Foliage Covered Terrain. (United States)


    approximate theories are derived from continuous random media theory while only a relatively few are based on the truly dis- S crete nature of the random media...The primary difficulty with trying to use continuous randon media theory for truly discrete media is that one is forced into defining a number of...scattering properties of an infinite half-space of foliage and a layer of foliage on a planar ground, respectively, using discrete ran- corn media theory . For

  14. Magnons and magnetodielectric effects in CoCr2O4 : Raman scattering studies (United States)

    Sethi, A.; Byrum, T.; McAuliffe, R. D.; Gleason, S. L.; Slimak, J. E.; Shoemaker, D. P.; Cooper, S. L.


    Magnetoelectric materials have generated wide technological and scientific interest because of the rich phenomena these materials exhibit, including the coexistence of magnetic and ferroelectric orders, magnetodielectric behavior, and exotic hybrid excitations such as electromagnons. The multiferroic spinel material CoCr2O4 is a particularly interesting example of a multiferroic material, because evidence for magnetoelectric behavior in the ferrimagnetic phase seems to conflict with traditional noncollinear-spin-driven mechanisms for inducing a macroscopic polarization. With the overall goal of clarifying the magnetodielectric behavior previously reported below TC in CoCr2O4 , in this paper we report an inelastic light scattering study of the magnon and phonon spectrum of CoCr2O4 as simultaneous functions of temperature, pressure, and magnetic field. Below the Curie temperature (TC=94 K ) of CoCr2O4 we observe a ω ˜16 cm-1 q =0 magnon having T1g-symmetry, which has the transformation properties of an axial vector. The anomalously large Raman intensity of the T1g-symmetry magnon is characteristic of materials with a large magneto-optical response and likely arises from large magnetic fluctuations that strongly modulate the dielectric response in CoCr2O4 . The Raman susceptibility of the T1g-symmetry magnon exhibits a strong magnetic-field dependence that is consistent with the magnetodielectric response observed in CoCr2O4 , suggesting that magnetodielectric behavior in CoCr2O4 primarily arises from the field-dependent suppression of magnetic fluctuations that are strongly coupled to long-wavelength phonons. Increasing the magnetic anisotropy in CoCr2O4 with applied pressure decreases the magnetic-field dependence of the T1g-symmetry magnon Raman susceptibility, suggesting that strain can be used to control the magnetodielectric response in CoCr2O4 .

  15. Wave scattering from statistically rough surfaces

    CERN Document Server

    Bass, F G; ter Haar, D


    Wave Scattering from Statistically Rough Surfaces discusses the complications in radio physics and hydro-acoustics in relation to wave transmission under settings seen in nature. Some of the topics that are covered include radar and sonar, the effect of variations in topographic relief or ocean waves on the transmission of radio and sound waves, the reproduction of radio waves from the lower layers of the ionosphere, and the oscillations of signals within the earth-ionosphere waveguide. The book begins with some fundamental idea of wave transmission theory and the theory of random processes a

  16. A Measurement of the Effective Electron Neutral Current Coupling Parameters from Polarized Bhabha Scattering at the Z0 Resonance

    Energy Technology Data Exchange (ETDEWEB)

    Langston, Matthew D


    The effective electron neutral current coupling parameters, {bar g}{sub V}{sup 3} and {bar g}{sub A}{sup c}, have been measured from analyzing 43,222 polarized Bhabha scattered events (e{sup +}e{sup -} {yields} e{sup +}e{sup -}) using the SLAC Large Detector (SLD) experiment at the Stanford Linear Accelerator Center (SLAC). The SLAC Linear Collider (SLC) produced the Bhabha scattered events by colliding polarized electrons, with an average polarization of 74%, with unpolarized positrons at an average center-of-mass energy of 91.25 GeV. The analysis used the entire SLD data sample collected between 1994 and 1998 (the last year the SLD detector collected data). The results are {bar g}{sub V}{sup e} = -0.0469 {+-} 0.0024 (stat.) {+-} 0.0004 (sys.); {bar g}{sub A}{sup e} = -0.5038 {+-} 0.0010 (stat.) {+-} 0.0043 (sys.). All Bhabha scattered events within the angular acceptance of the SLD calorimeter subsystems were used in this analysis, including both small-angle events (28 mrad. {le} theta {le} 68 mrad.) measured by the Silicon/Tungsten Luminosity Monitor (LUM), and large angle events (0 {le} |cos{theta}| {le} 0.9655) measured by the Liquid Argon Calorimeter (LAC). Using all of the data in this manner allows for the high-precision measurement of the luminosity provided by the LUM to constrain the uncertainty on {bar g}{sub V}{sup e} and {bar g}{sub A}{sup e}. The measured integrated luminosity for the combined 1993 through 1998 SLD data sample is L{sub Integrated} = 19,247 {+-} 17 (stat.) {+-} 146 (sys.) nb{sup -1}. In contrast with other SLD precision measurements of the effective weak mixing angle, which are sensitive to the ratio {bar g}{sub V}{sup e}/{bar g}{sub A}{sup e}, this result independently determines {bar g}{sub V}{sup 3} and {bar g}{sub A}{sup c}. The analysis techniques to measure {bar g}{sub V}{sup 3} and {bar g}{sub A}{sup c} are described, and the results are compared with other SLD measurements as well as other experiments.

  17. Body Temperature Controlled Optical and Thermal Information Storage Light Scattering Display with Fluorescence Effect and High Mechanical Strength. (United States)

    Chen, Si; Tong, Xiaoqian; He, Huiwen; Ma, Meng; Shi, Yanqin; Wang, Xu


    A kind of body temperature controlled optical and thermal information storage light scattering display based on super strong liquid crystalline physical gel with special "loofah-like gel network" was successfully prepared. Such liquid crystal (LC) gel was obtained by mixing a dendritic gelator (POSS-G1-BOC), an azobenzene compound (2Azo2), and a phosphor tethered liquid crystalline host (5CB), which could show its best contrast ratio at around human body temperature under UV light because of the phosphor's fluorescence effect. The gel also has quite strong mechanical strength, which could be used in wearable device field especially under sunlight, even under the forcing conditions as harsh as being centrifuged for 10 min at the speed of 2000 r/min. The whole production process of such a display is quite simple and could lead to displays at any size through noncontact writing. We believe it will have wide applications in the future.

  18. Large enhancement of the spin Hall effect in Au by side-jump scattering on Ta impurities (United States)

    Laczkowski, P.; Fu, Y.; Yang, H.; Rojas-Sánchez, J.-C.; Noel, P.; Pham, V. T.; Zahnd, G.; Deranlot, C.; Collin, S.; Bouard, C.; Warin, P.; Maurel, V.; Chshiev, M.; Marty, A.; Attané, J.-P.; Fert, A.; Jaffrès, H.; Vila, L.; George, J.-M.


    We present measurements of the spin Hall effect (SHE) in AuW and AuTa alloys for a large range of W or Ta concentrations by combining experiments on lateral spin valves and ferromagnetic-resonance/spin-pumping techniques. The main result is the identification of a large enhancement of the spin Hall angle (SHA) by the side-jump mechanism on Ta impurities, with a SHA as high as +0.5 (i.e., 50 % ) for about 10% of Ta. In contrast, the SHA in AuW does not exceed +0.15 and can be explained by intrinsic SHE of the alloy without significant extrinsic contribution from skew or side-jump scattering by W impurities. The AuTa alloys, as they combine a very large SHA with a moderate resistivity (smaller than 85 μ Ω cm ), are promising for spintronic devices exploiting the SHE.

  19. Double parton scattering: A study of the effective cross section within a Light-Front quark model

    Directory of Open Access Journals (Sweden)

    Matteo Rinaldi


    Full Text Available We present a calculation of the effective cross section σeff, an important ingredient in the description of double parton scattering in proton–proton collisions. Our theoretical approach makes use of a Light-Front quark model as a framework to calculate the double parton distribution functions at low-resolution scale. QCD evolution is implemented to reach the experimental scale. The obtained values of σeff in the valence region are consistent with the present experimental scenario, in particular with the sets of data which include the same kinematical range. However the result of the complete calculation shows a dependence of σeff on xi, a feature not easily seen in the available data, probably because of their low accuracy. Measurements of σeff in restricted xi regions are addressed to obtain indications on double parton correlations, a novel and interesting aspect of the three dimensional structure of the nucleon.

  20. Quantum scattering in one dimension

    Energy Technology Data Exchange (ETDEWEB)

    Barlette, Vania E. [Centro Universitario Franciscano, Santa Maria, RS (Brazil); Leite, Marcelo M. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Centro Tecnico Aeroespacial, Sao Jose dos Campos, SP (Brazil); Adhikari, Sadhan K. [Instituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, SP (Brazil)


    A self-contained discussion of non-relativistic quantum scattering is presented in the case of central potentials in one space dimension, which will facilitate the understanding of the more complex scattering theory in two and three dimensions. The present discussion illustrates in a simple way the concepts of partial-wave decomposition, phase shift, optical theorem and effective-range expansion. (author)

  1. Levitation effect in zeolites: Quasielastic neutron scattering and molecular dynamics study of pentane isomers in zeolite NaY. (United States)

    Borah, Bhaskar J; Jobic, H; Yashonath, S


    We report the quasielastic neutron scattering (QENS) and molecular dynamics (MD) investigations into diffusion of pentane isomers in zeolite NaY. The molecular cross section perpendicular to the long molecular axis varies for the three isomers while the mass and the isomer-zeolite interaction remains essentially unchanged. Both QENS and MD results show that the branched isomers neopentane and isopentane have higher self-diffusivities as compared with n-pentane at 300 K in NaY zeolite. This result provides direct experimental evidence for the existence of nonmonotonic, anomalous dependence of self-diffusivity on molecular diameter known as the levitation effect. The energetic barrier at the bottleneck derived from MD simulations exists for n-pentane which lies in the linear regime while no such barrier is seen for neopentane which is located clearly in the anomalous regime. Activation energy is in the order E(a)(n-pentane)>E(a)(isopentane)>E(a)(neopentane) consistent with the predictions of the levitation effect. In the liquid phase, it is seen that D(n-pentane)>D(isopentane)>D(neopentane) and E(a)(n-pentane)scattering function for small wavenumbers obtained from MD follows a single exponential decay for neopentane and isopentane. For n-pentane, a single exponential fit provides a poor fit especially at short times. Cage residence time is largest for n-pentane and lowest for neopentane. For neopentane, the width of the self-part of the dynamic structure factor shows a near monotonic decrease with wavenumber. For n-pentane a minimum is seen near k=0.5 A(-1) suggesting a slowing down of motion around the 12-ring window, the bottleneck for diffusion. Finally, the result that the branched isomer has a higher diffusivity as compared with the linear analog is at variation from what is normally seen.

  2. Effectiveness of topic-specific infobuttons: a randomized controlled trial. (United States)

    Del Fiol, Guilherme; Haug, Peter J; Cimino, James J; Narus, Scott P; Norlin, Chuck; Mitchell, Joyce A


    Infobuttons are decision support tools that provide links within electronic medical record systems to relevant content in online information resources. The aim of infobuttons is to help clinicians promptly meet their information needs. The objective of this study was to determine whether infobutton links that direct to specific content topics ("topic links") are more effective than links that point to general overview content ("nonspecific links"). Randomized controlled trial with a control and an intervention group. Clinicians in the control group had access to nonspecific links, while those in the intervention group had access to topic links. Infobutton session duration, number of infobutton sessions, session success rate, and the self-reported impact that the infobutton session produced on decision making. The analysis was performed on 90 subjects and 3,729 infobutton sessions. Subjects in the intervention group spent 17.4% less time seeking for information (35.5 seconds vs. 43 seconds, p = 0.008) than those in the control group. Subjects in the intervention group used infobuttons 20.5% (22 sessions vs. 17.5 sessions, p = 0.21) more often than in the control group, but the difference was not significant. The information seeking success rate was equally high in both groups (89.4% control vs. 87.2% intervention, p = 0.99). Subjects reported a high positive clinical impact (i.e., decision enhancement or knowledge update) in 62% of the sessions. Limitations The exclusion of users with a low frequency of infobutton use and the focus on medication-related information needs may limit the generalization of the results. The session outcomes measurement was based on clinicians' self-assessment and therefore prone to bias. The results support the hypothesis that topic links are more efficient than nonspecific links regarding the time seeking for information. It is unclear whether the statistical difference demonstrated will result in a clinically significant impact

  3. Optical scattering in glass ceramics

    NARCIS (Netherlands)

    Mattarelli, M.; Montagna, M.; Verrocchio, P.


    The transparency of glass ceramics with nanocrystals is generally higher than that expected from the theory of Rayleigh scattering. We attribute this ultra-transparency to the spatial correlation of the nanoparticles. The structure factor is calculated for a simple model system, the random

  4. Boundary effects on effective conductivity of random heterogeneous media with spherical inclusions (United States)

    Rabinovich, A.; Dagan, G.; Miloh, T.


    It is common to determine the effective conductivity of heterogeneous media by assuming stationarity of the random local properties. This assumption is not obeyed in a boundary layer of a body of finite size. The effect of different types of boundaries is examined for a two-phase medium with spherical inclusions of given conductivity distributed randomly in a matrix of a different conductivity. Exact solutions are derived for the apparent conductivity and the boundary layer thickness. The interaction between the spheres and the boundaries is fully incorporated in the solutions using a spherical harmonics expansion and the method of images. As applications, the corrections for the effective conductivity are given for two cases of finite bodies: the Maxwell sphere and a cylinder of flow parallel to the axis.

  5. Cluster randomized trials in comparative effectiveness research: randomizing hospitals to test methods for prevention of healthcare-associated infections. (United States)

    Platt, Richard; Takvorian, Samuel U; Septimus, Edward; Hickok, Jason; Moody, Julia; Perlin, Jonathan; Jernigan, John A; Kleinman, Ken; Huang, Susan S


    The need for evidence about the effectiveness of therapeutics and other medical practices has triggered new interest in methods for comparative effectiveness research. Describe an approach to comparative effectiveness research involving cluster randomized trials in networks of hospitals, health plans, or medical practices with centralized administrative and informatics capabilities. We discuss the example of an ongoing cluster randomized trial to prevent methicillin-resistant Staphylococcus aureus (MRSA) infection in intensive care units (ICUs). The trial randomizes 45 hospitals to: (a) screening cultures of ICU admissions, followed by Contact Precautions if MRSA-positive, (b) screening cultures of ICU admissions followed by decolonization if MRSA-positive, or (c) universal decolonization of ICU admissions without screening. All admissions to adult ICUs. The primary outcome is MRSA-positive clinical cultures occurring >or=2 days following ICU admission. Secondary outcomes include blood and urine infection caused by MRSA (and, separately, all pathogens), as well as the development of resistance to decolonizing agents. Recruitment of hospitals is complete. Data collection will end in Summer 2011. This trial takes advantage of existing personnel, procedures, infrastructure, and information systems in a large integrated hospital network to conduct a low-cost evaluation of prevention strategies under usual practice conditions. This approach is applicable to many comparative effectiveness topics in both inpatient and ambulatory settings.

  6. Effect of polarization Coulomb field scattering on device linearity in AlGaN/GaN heterostructure field-effect transistors (United States)

    Cui, Peng; Lv, Yuanjie; Lin, Zhaojun; Fu, Chen; Liu, Yan


    The power gain for the AlGaN/GaN heterostructure field-effect transistors (HFETs) has been measured, and a distinct difference of device linearity for a single device under two types of direct current quiescent points was observed. Based on the analyses of the variation of the transconductance and the parasitic source access resistance, it is found that polarization Coulomb field scattering can affect the power gain and the device linearity. We show that this is an effective approach to improve the linearity of AlGaN/GaN HFETs.

  7. Identification and estimation of nonseparable single-index models in panel data with correlated random effects

    NARCIS (Netherlands)

    Cizek, Pavel; Lei, Jinghua

    The identification in a nonseparable single-index models with correlated random effects is considered in panel data with a fixed number of time periods. The identification assumption is based on the correlated random effects structure. Under this assumption, the parameters of interest are identified

  8. Identification and Estimation of Nonseparable Single-Index Models in Panel Data with Correlated Random Effects

    NARCIS (Netherlands)

    Cizek, P.; Lei, J.


    Abstract: The identification of parameters in a nonseparable single-index models with correlated random effects is considered in the context of panel data with a fixed number of time periods. The identification assumption is based on the correlated random-effect structure: the distribution of

  9. Local lattice relaxations in random metallic alloys: Effective tetrahedron model and supercell approach

    DEFF Research Database (Denmark)

    Ruban, Andrei; Simak, S.I.; Shallcross, S.


    We present a simple effective tetrahedron model for local lattice relaxation effects in random metallic alloys on simple primitive lattices. A comparison with direct ab initio calculations for supercells representing random Ni0.50Pt0.50 and Cu0.25Au0.75 alloys as well as the dilute limit of Au-ri...

  10. Technology diffusion in hospitals : A log odds random effects regression model

    NARCIS (Netherlands)

    Blank, J.L.T.; Valdmanis, V.G.


    This study identifies the factors that affect the diffusion of hospital innovations. We apply a log odds random effects regression model on hospital micro data. We introduce the concept of clustering innovations and the application of a log odds random effects regression model to describe the

  11. Technology diffusion in hospitals: A log odds random effects regression model

    NARCIS (Netherlands)

    J.L.T. Blank (Jos); V.G. Valdmanis (Vivian G.)


    textabstractThis study identifies the factors that affect the diffusion of hospital innovations. We apply a log odds random effects regression model on hospital micro data. We introduce the concept of clustering innovations and the application of a log odds random effects regression model to

  12. Advanced optical imaging with scattering lenses

    NARCIS (Netherlands)

    Yilmaz, H.


    This thesis describes new advanced optical methods to control light propagation through disordered nanophotonic materials for focusing and high‐resolution imaging applications. A combination of light scattering, wavefront control, and our new image processing algorithms enable using random

  13. A random effect multiplicative heteroscedastic model for bacterial growth

    Directory of Open Access Journals (Sweden)

    Quinto Emiliano J


    Full Text Available Abstract Background Predictive microbiology develops mathematical models that can predict the growth rate of a microorganism population under a set of environmental conditions. Many primary growth models have been proposed. However, when primary models are applied to bacterial growth curves, the biological variability is reduced to a single curve defined by some kinetic parameters (lag time and growth rate, and sometimes the models give poor fits in some regions of the curve. The development of a prediction band (from a set of bacterial growth curves using non-parametric and bootstrap methods permits to overcome that problem and include the biological variability of the microorganism into the modelling process. Results Absorbance data from Listeria monocytogenes cultured at 22, 26, 38, and 42°C were selected under different environmental conditions of pH (4.5, 5.5, 6.5, and 7.4 and percentage of NaCl (2.5, 3.5, 4.5, and 5.5. Transformation of absorbance data to viable count data was carried out. A random effect multiplicative heteroscedastic model was considered to explain the dynamics of bacterial growth. The concept of a prediction band for microbial growth is proposed. The bootstrap method was used to obtain resamples from this model. An iterative procedure is proposed to overcome the computer intensive task of calculating simultaneous prediction intervals, along time, for bacterial growth. The bands were narrower below the inflection point (0-8 h at 22°C, and 0-5.5 h at 42°C, and wider to the right of it (from 9 h onwards at 22°C, and from 7 h onwards at 42°C. A wider band was observed at 42°C than at 22°C when the curves reach their upper asymptote. Similar bands have been obtained for 26 and 38°C. Conclusions The combination of nonparametric models and bootstrap techniques results in a good procedure to obtain reliable prediction bands in this context. Moreover, the new iterative algorithm proposed in this paper allows one to

  14. Effective sampling of random surfaces by baby universe surgery

    NARCIS (Netherlands)

    Ambjørn, J.; Białas, P.; Jurkiewicz, J.; Burda, Z.; Petersson, B.


    We propose a new, very efficient algorithm for sampling of random surfaces in the Monte Carlo simulations, based on so-called baby universe surgery, i.e. cutting and pasting of baby universe. It drastically reduces slowing down as compared to the standard local flip algorithm, thereby allowing

  15. The Damage Effects in Steel Bridges under Highway Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning; Nielsen, Jette Andkjær


    In the present investigation, fatigue damage accumulation in steel bridges under highway random loading is studied. In the experimental part of the investigation, fatigue test series on welded plate test specimens have been carried through. The fatigue tests have been carried out using load...

  16. Universal chaotic scattering on quantum graphs. (United States)

    Pluhař, Z; Weidenmüller, H A


    We calculate the S-matrix correlation function for chaotic scattering on quantum graphs and show that it agrees with that of random-matrix theory. We also calculate all higher S-matrix correlation functions in the Ericson regime. These, too, agree with random-matrix theory results as far as the latter are known. We conjecture that our results give a universal description of chaotic scattering.

  17. Polarized proton scattering on Ni-58 at small momentum transfer : A test of the microscopic optical model and effective interactions

    NARCIS (Netherlands)

    Hofmann, F; Baumer, C; van den Berg, AM; Frekers, D; Hannen, VM; Harakeh, MN; de Huu, MA; Kalmykov, Y; von Neumann-Cosel, P; Ponomarev, VY; Reitz, B; Richter, A; Shevchenko, A; Schweda, K; Wambach, J; Wortche, HJ


    The reaction Ni-58((p) over right arrow, (p) over right arrow (/)) has been studied at small scattering angles and an incident beam energy of 172 MeV. We extract cross sections and analyzing powers for elastic scattering and transitions to vibrational states at low excitation energies. The data are

  18. Effect of Grafting Density of Random Copolymer Brushes on Perpendicular Alignment in PS-b-PMMA Thin Films

    KAUST Repository

    Lee, Wooseop


    We modulated the grafting density (σ) of a random copolymer brush of poly(styrene-r-methyl methacrylate) on substrates to probe its effect on the formation of perpendicularly aligned lamellae of polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA). Supported by coarse-grained simulation results, we hypothesized that an increase in σ will allow us to systematically tune the block copolymer interfacial interactions with the substrates from being preferential to one of the blocks to being neutral toward both blocks and will thereby facilitate enhanced regimes of perpendicularly aligned lamellae. We verified such a hypothesis by using a simple grafting-to approach to modify the substrates and characterized the thickness window for perpendicular lamellae as a function of brush thickness (or σ) on the grafted substrates using scanning force microscopy (SFM) images and grazing incidence small-angle X-ray scattering (GISAXS) measurements. The experimental results validated our hypothesis and suggested that the σ of random copolymer brushes can be used as an additional versatile parameter to modulate the interfacial interactions and the resulting alignment of block copolymer films.

  19. An experimental study of light scattering by large, irregular particles (United States)

    Mcguire, Audrey F.; Hapke, Bruce W.


    The intensity and polarization of light scattered by a variety of types of artificial partices large compared to the wavelength were measured as a function of phase angle. Shape, surface roughness, absorption coefficient, and internal scattering coefficient were varied systematically and their effects studied. Scattering by clear, smooth-surfaced spheres is in quantitative agreement with the predictions of the geometrical optics (ray theory) approximation to physical optics (Mie theory). The phase functions of almost all of the particles measured have both forward and backward scattering lobes. A two-parameter, double Henyey-Greenstein function generally provides reasonably good descriptions of the data, while keeping the number of free parameters to the minimum necessary. On a double Henyey- Greenstein parameter plot all of the particles fall into an L-shaped area of restricted size in which the location is characteristic of the particle type. Formalisms based on the equivalent slab model are also given for estimating the scattering efficiency of a large, irregular particle. For most dielectric particles the transmitted, forward scattered light is partially negatively polarized. It is this component that is respopnsible for the well-known maximum in the polarization curves of planetary regoliths at phase angles around 100 deg. For phase angles between about 30 deg and 70 deg the internally scattered light is found to be randomly polarized in the particles studied here, so that the only contribution to the second component of the Stokes vector is by Fresnel reflection from the particle surface. If this empirical result is general, measurement of the second Stokes vector of the light scattered from a regolith at these angles may provide a method of remotely measuring the mean refractive index.

  20. Objective and perceptual evaluation of distance-dependent scattered sound effects in a small variable-acoustics hall. (United States)

    Shtrepi, Louena; Astolfi, Arianna; D'Antonio, Gianluca; Guski, Martin


    Performance spaces are characterized by a complex sound field, due to the presence of absorptive and diffusive surfaces. In situ evaluations of the acoustic effects that these surfaces have on the objective acoustic parameters and on sound perception have not yet been fully understood. To this aim, acoustic measurements have been performed in a variable-acoustic concert hall, the Espace de Projection, at the Institut de Recherche et Coordination Acoustique/Musique. These measurements have allowed the effects of one single wall to be determined. A diffusive and a reflective condition of one of the long lateral walls of the shoebox-like hall have been considered, while the other surfaces have been fixed in absorptive mode. Measurements have been carried out at different distances from the test wall, using an artificial head and an array of omnidirectional microphones. Objective acoustic parameters, such as early decay time, reverberation time (T30), clarity (C80), definition (D50), and interaural cross correlation, have been compared between both conditions. In addition to the objective indexes, a perceptual evaluation has been performed using listening tests that had the purpose of determining the maximum distance from a diffusive surface at which acoustic scattering effects are still audible.

  1. X-ray scattering and electron cryomicroscopy study on the effect of carotenoid biosynthesis to the structure of Chlorobium tepidum chlorosomes

    DEFF Research Database (Denmark)

    Ikonen, T P; Li, H; Psencík, J


    Chlorosomes, the main antenna complexes of green photosynthetic bacteria, were isolated from null mutants of Chlorobium tepidum, each of which lacked one enzyme involved in the biosynthesis of carotenoids. The effects of the altered carotenoid composition on the structure of the chlorosomes were...... in the arrangement of lamellae and spacing between the lamellar planes of bacteriochlorophyll aggregates. In addition, comparisons among the various mutants enabled refinement of the assignments of the x-ray scattering peaks. While the main scattering peaks come from the lamellar structure of bacteriochlorophyll c...

  2. Scaling of the anomalous Hall effect in epitaxial antiperovskite Mn{sub 3.5}Dy{sub 0.5}N involving multiple competing scattering mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Meng, M.; Wu, S. X., E-mail:; Zhou, W. Q.; Li, S. W., E-mail: [State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)


    Anomalous Hall effect (AHE) has been studied for ferrimagnetic antiperovskite Mn{sub 3.5}Dy{sub 0.5}N film grown by molecular-beam epitaxy. Reflective high energy electron diffraction and transmission electron microscopy demonstrate the high quality of the film. We have used a scaling involving multiple competing scattering mechanisms to distinguish variations of contributions to the AHE by heavily doped Dy. The scaling analysis revealed that the heavily doped Dy has dramatically modified the skew scattering part of the AHE in Mn{sub 4}N and Mn{sub 3.5}Dy{sub 0.5}N has a totally different scattering mechanism from an undoped film.

  3. Gas molecule-molecule interaction and the gas-surface scattering effect on the rarefied gas flow through a slit into a vacuum (United States)

    Sazhin, O.


    The effect of the gas molecule-molecule interaction and the gas-surface scattering on the gas flow through a slit into a vacuum are investigated in a wide range of the gas rarefaction using the direct simulation Monte Carlo method. To study the gas molecule-molecule interaction influence, we used the variable hard sphere and variable soft sphere models defined for an inverse-power-law potential and the generalized hard sphere model defined for the 12-6 Lennard-Jones potential. The Maxwell, Cercignani-Lampis, and Epstein models were used to simulate the gas-surface scattering. This study demonstrates that the gas molecule-molecule interaction can have a significant influence on the rarefied gas flow through a slit, while the influence of the gas-surface scattering is negligibly small. The presented numerical results are in agreement with the corresponding experimental ones.

  4. Investigation of magnon dispersion relations and neutron scattering cross sections with special attention to anisotropy effects

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Kowalska, A.; Laut, Peter


    -helical structure. A numerical calculation is performed for terbium on the basis of the Kaplan-Lyons Hamiltonian with added crystalline anisotropy. The non-istropic exchange part is shown to have a small effect on the dispersion curves, and it turns out that radical changes of the Ruderman-Kittel-type functions...... for the exchange interaction seem to be necessary for agreement with experimental dispersion curves be obtained. The effect of the anisotropy in the cross section is estimated and shown to be important for small magnon energies....

  5. Small Angle Neutron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Volker S [ORNL


    Small Angle Neutron Scattering (SANS) probes structural details at the nanometer scale in a non-destructive way. This article gives an introduction to scientists who have no prior small-angle scattering knowledge, but who seek a technique that allows elucidating structural information in challenging situations that thwart approaches by other methods. SANS is applicable to a wide variety of materials including metals and alloys, ceramics, concrete, glasses, polymers, composites and biological materials. Isotope and magnetic interactions provide unique methods for labeling and contrast variation to highlight specific structural features of interest. In situ studies of a material s responses to temperature, pressure, shear, magnetic and electric fields, etc., are feasible as a result of the high penetrating power of neutrons. SANS provides statistical information on significant structural features averaged over the probed sample volume, and one can use SANS to quantify with high precision the structural details that are observed, for example, in electron microscopy. Neutron scattering is non-destructive; there is no need to cut specimens into thin sections, and neutrons penetrate deeply, providing information on the bulk material, free from surface effects. The basic principles of a SANS experiment are fairly simple, but the measurement, analysis and interpretation of small angle scattering data involves theoretical concepts that are unique to the technique and that are not widely known. This article includes a concise description of the basics, as well as practical know-how that is essential for a successful SANS experiment.

  6. Critical fluid light scattering (United States)

    Gammon, Robert W.


    The objective is to measure the decay rates of critical density fluctuations in a simple fluid (xenon) very near its liquid-vapor critical point using laser light scattering and photon correlation spectroscopy. Such experiments were severely limited on Earth by the presence of gravity which causes large density gradients in the sample when the compressibility diverges approaching the critical point. The goal is to measure fluctuation decay rates at least two decades closer to the critical point than is possible on earth, with a resolution of 3 microK. This will require loading the sample to 0.1 percent of the critical density and taking data as close as 100 microK to the critical temperature. The minimum mission time of 100 hours will allow a complete range of temperature points to be covered, limited by the thermal response of the sample. Other technical problems have to be addressed such as multiple scattering and the effect of wetting layers. The experiment entails measurement of the scattering intensity fluctuation decay rate at two angles for each temperature and simultaneously recording the scattering intensities and sample turbidity (from the transmission). The analyzed intensity and turbidity data gives the correlation length at each temperature and locates the critical temperature. The fluctuation decay rate data from these measurements will provide a severe test of the generalized hydrodynamic theories of transport coefficients in the critical regions. When compared to equivalent data from binary liquid critical mixtures they will test the universality of critical dynamics.

  7. Crystal structure and charge distribution of pyrazine: effects of extinction, thermal diffuse scattering and series termination

    NARCIS (Netherlands)

    de With, G.; Harkema, Sybolt; Feil, D.


    The crystal structure and electronic charge distribution of pyrazine (1,4-diazabenzene) has been determined at 184 K by X-ray methods. The structural results of Wheatley [Acta Cryst. (1957), 10, 182-187] have been confirmed. A clear indication of bonding effects is obtained. Neither positional and

  8. Particle-vibration coupling and exchange-current effects on the magnetic electron-scattering form factor

    Energy Technology Data Exchange (ETDEWEB)

    Krewald, S.; Lallena, A.M.; Dehesa, J.S.


    Inelastic electron-scattering form factors of magnetic states in closed-shell nuclei are calculated taking into account the combined effect of the mesonic degrees of freedom and the two-particle-two-hole components of the nuclear wave functions which come from the particle-core vibration coupling. The one-body nucleon- and two-body meson-exchange current contribution to the form factor are evaluated with the same realistic mean field. Application to various high-spin magnetic states of oxygen and lead is made. The comparison with experiment shows an excellent agreement for the states 14/sup -/(6.74 MeV) and 12/sup -/sub(t)(7.06 MeV) in lead, while such is not the case for the second 12/sup -//sub 2/(6.43 MeV) state in lead and the 4/sup -/(18.98 MeV) state in oxygen essentially due to mixing configuration effects and the non-consideration of 3p3h excitations, respectively. (orig.).

  9. Classical and quantum scattering in optical systems

    NARCIS (Netherlands)

    Puentes, Graciana


    The central topic of the Thesis concerns light scattering experiments with entangled photons. Specifically, we study the effect of scattering processes on polarization-entanglement of twin-photons. The main idea is that scattering generally couples polarization and spatial degrees of freedom of

  10. Ipsilateral transversus abdominis plane block provides effective analgesia after appendectomy in children: a randomized controlled trial.

    LENUS (Irish Health Repository)

    Carney, John


    The transversus abdominis plane (TAP) block provides effective postoperative analgesia in adults undergoing major abdominal surgery. Its efficacy in children remains unclear, with no randomized clinical trials in this population. In this study, we evaluated its analgesic efficacy over the first 48 postoperative hours after appendectomy performed through an open abdominal incision, in a randomized, controlled, double-blind clinical trial.

  11. Effect of Playful Balancing Training - A Pilot Randomized Controlled Trial

    DEFF Research Database (Denmark)

    Lund, Henrik Hautop; Jessen, Jari Due


    We used the modular playware in the form of modular interactive tiles for playful training of community-dwelling elderly with balancing problem. During short-term play on the modular interactive tiles, the elderly were playing physical, interactive games that were challenging their dynamic balance......, agility, endurance, and sensor-motoric reaction. A population of 12 elderly (average age: 79) with balancing problems (DGI average score: 18.7) was randomly assigned to control group or tiles training group, and tested before and after intervention. The tiles training group had statistical significant...

  12. Effects of Cofactors on Conformation Transition of Random Peptides Consisting of a Reduced Amino Acid Alphabet. (United States)

    Lu, Ming-Feng; Xie, Ying; Zhang, Yue-Jie; Xing, Xue-Yan


    This study aims to explore the structure characteristic of random polypeptides constructed by origin early amino acid alphabet, as well as the effects of cofactors on conformation transition of random peptides. DNA library R8-4 encoding VNM random peptides were constructed by small cassette strategy. Subsequently, a random polypeptide library was constructed using in vitro translation. Expression and purification of VNM random peptides were also performed by a conventional method of recombinant. CD spectrum analysis indicated that VNM random polypeptides have a secondary structure characteristic of protein, such as the content of α-helix is greater than 60%, random coil is about 20% β sheet, and β turn is less than 10%. CD spectrum changed with the addition of 10-40 µM ATP and NADP, but slightly changed by NAD; no influence was observed with MgSO4. Bis-ANS binding assay indicated that fluorescent intensity of bis-ANS was strengthened slightly by 10 VNM random peptides. Fluorescent intensity was strengthened fourfold by adding 10-40 µM ATP, NAD, and NADH, whereas the inducing effect of NADPH and MgSO4 were negligible. VNM random peptides have a classic secondary structure and hydrophobic domain in water solution. Moreover, conformation transition and hydrophobic domain could be induced by cofactor, indicating the preliminary evidence for the hypothesis that "the origin of primitive protein was induced by small molecule."

  13. Indication of the Hanle Effect by Comparing the Scattering Polarization Observed by CLASP in the Ly α and Si iii 120.65 nm Lines

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, R.; Kubo, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa, Y.; Giono, G.; Suematsu, Y.; Hara, H. [National Astronomical Observatory of Japan, National Institutes of Natural Science, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Bueno, J. Trujillo [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); Uitenbroek, H. [National Solar Observatory, 3665 Discovery Drive, Boulder, CO 80303 (United States); Tsuneta, S.; Ishikawa, S.; Shimizu, T.; Sakao, T. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Goto, M. [National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu 509-5292 (Japan); Winebarger, A.; Kobayashi, K. [NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812 (United States); Cirtain, J. [University of Virginia, Department of Astronomy, 530 McCormick Road, Charlottesville, VA 22904 (United States); Champey, P. [University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, AL 35899 (United States); and others


    The Chromospheric Lyman-Alpha Spectro-Polarimeter is a sounding rocket experiment that has provided the first successful measurement of the linear polarization produced by scattering processes in the hydrogen Ly α line (121.57 nm) radiation of the solar disk. In this paper, we report that the Si iii line at 120.65 nm also shows scattering polarization and we compare the scattering polarization signals observed in the Ly α and Si iii lines in order to search for observational signatures of the Hanle effect. We focus on four selected bright structures and investigate how the U / I spatial variations vary between the Ly α wing, the Ly α core, and the Si iii line as a function of the total unsigned photospheric magnetic flux estimated from Solar Dynamics Observatory /Helioseismic and Magnetic Imager observations. In an internetwork region, the Ly α core shows an antisymmetric spatial variation across the selected bright structure, but it does not show it in other more magnetized regions. In the Si iii line, the spatial variation of U / I deviates from the above-mentioned antisymmetric shape as the total unsigned photospheric magnetic flux increases. A plausible explanation of this difference is the operation of the Hanle effect. We argue that diagnostic techniques based on the scattering polarization observed simultaneously in two spectral lines with very different sensitivities to the Hanle effect, like Ly α and Si iii, are of great potential interest for exploring the magnetism of the upper solar chromosphere and transition region.

  14. Multiple small-angle neutron scattering studies of anisotropic materials

    CERN Document Server

    Allen, A J; Long, G G; Ilavsky, J


    Building on previous work that considered spherical scatterers and randomly oriented spheroidal scatterers, we describe a multiple small-angle neutron scattering (MSANS) analysis for nonrandomly oriented spheroids. We illustrate this with studies of the multi-component void morphologies found in plasma-spray thermal barrier coatings. (orig.)

  15. On scattered subword complexity

    CERN Document Server

    Kása, Zoltán


    Special scattered subwords, in which the gaps are of length from a given set, are defined. The scattered subword complexity, which is the number of such scattered subwords, is computed for rainbow words.

  16. Semiclassical scattering amplitudes of dressed gravitons


    Kang, Kyungsik; Kondrashuk, Igor


    We consider effective action for the Einstein gravity and show that dressed mean fields are actual variables of the effective action. Kernels of this effective action expressed in terms of dressed effective fields are constituent parts of scattering amplitudes for gravitons. Possible applications to the graviton scattering and black hole formation are discussed at the semiclassical level. In particular, we consider graviton scattering in four dimensions based on the Lipatov effective action f...

  17. Dichroic interference effects in circularly polarized soft-x-ray resonant magnetic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kao, C. (National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)); Chen, C.T. (AT T Bell Laboratories, Murray Hill, New Jersey 07974 (United States)); Johnson, E.D.; Hastings, J.B. (National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)); Lin, H.J. (AT T Bell Laboratories, Murray Hill, New Jersey 07974 (United States)); Ho, G.H. (Department of Physics, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)); Meigs, G. (AT T Bell Laboratories, Murray Hill, New Jersey 07974 (United States)); Brot, J.; Hulbert, S.L. (National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)); Idzerda, Y.U. (Naval Research Laboratory, Washington, D.C. 20375 (United States)); Vettier, C. (European Synchrotron Radiation Facility, BP220, F-38043 Grenoble CEDEX (France))


    Dichroic interference effects were observed in circularly polarized soft-x-ray reflectivity at the Co [ital L][sub 2,3] edges of a magnetic multilayer. The data show a maximum asymmetry ratio of 80%, greater than the degree of circular polarization of the incident light, a changeover in the dichroic characteristics with increasing grazing angle, and an inverted interference pattern in the angular dependence of the asymmetry ratio. These observations are explained successfully by a classical electromagnetic model calculation which includes the complete polarization state of the incident light and spatial interference within the multilayer.

  18. Spin-orbit scattering in superconducting nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Alhassid, Y. [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut, 06520 (United States); Nesterov, K.N. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin, 53706 (United States)


    We review interaction effects in chaotic metallic nanoparticles. Their single-particle Hamiltonian is described by the proper random-matrix ensemble while the dominant interaction terms are invariants under a change of the single-particle basis. In the absence of spin-orbit scattering, the nontrivial invariants consist of a pairing interaction, which leads to superconductivity in the bulk, and a ferromagnetic exchange interaction. Spin-orbit scattering breaks spin-rotation invariance and when it is sufficiently strong, the only dominant nontrivial interaction is the pairing interaction. We discuss how the magnetic response of discrete energy levels of the nanoparticle (which can be measured in single-electron tunneling spectroscopy experiments) is affected by such pairing correlations and how it can provide a signature of pairing correlations. We also consider the spin susceptibility of the nanoparticle and discuss how spin-orbit scattering changes the signatures of pairing correlations in this observable. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Double parton scattering in CMS

    CERN Document Server

    Sunar Cerci, Deniz


    Recent results on the double parton scattering measurements performed using the proton-proton collision data collected with the CMS detector are presented. The observables, which are sensitive to double parton scattering, are investigated after being corrected for detector effects and selection efficiencies. Multivariate analysis techniques are used for increasing the sensitivity. The effective cross section, $\\sigma_{eff}$ is also extracted using different processes at various center-of-mass energies.

  20. Modelling the effect of fractures in geothermal reservoirs on the seismic wave field - anisotropy, scattering and localisation (United States)

    Möller, Thomas; Friederich, Wolfgang


    Fractures and cracks in rocks have a significant influence on the propagation of seismic waves. Their presence causes reflections and scattering of the waves and generates effective anisotropy within the rocks. In geothermics, gaining information on how a system of fractures affects the wave field is of great importance for reservoir characterisation. We present a numerical approach to the simulation of seismic wave propagation in fractured media that does not require explicit modelling of the fracture itself, but uses the concept of linear slip interfaces developed by Schoenberg (1980). This concept states that at an interface between two imperfectly bonded elastic media, stress is continuous across the interface while displacement is discontinuous. It is assumed that the jump of displacement is proportional to stress which implies a jump in particle velocity at the interface. We use this concept as a boundary condition to the elastic wave equation and solve this equation in the framework of a Nodal Discontinuous Galerkin scheme using a velocity-stress formulation. The concept of linear slip interfaces has been implemented into the 1D and 2D versions of the discontinuous Galerkin solver "NEXD". We verified the implementation for the case of an elastic linear slip interface. We use this concept to demonstrate the effect of fractures by the following examples: (1) A system of parallel fractures embedded in a homogenous background medium with a source in the center of the system and (2) varyingly oriented fracture systems embedded in a sample reservoir with layered velocity structure. We show that waves traveling perpendicular to the fractures experience high attenuation whereas waves traveling parallel to the fractures are almost not influenced. Synthetic seismograms show a distinct change in curvature of the wavefront when fractures are present, underlining the effective anisotropy caused by the fractures. In addition we show the contribution such systems have to

  1. Class of exactly solvable scattering potentials in two dimensions, entangled-state pair generation, and a grazing-angle resonance effect (United States)

    Loran, Farhang; Mostafazadeh, Ali


    We provide an exact solution of the scattering problem for the potentials of the form v (x ,y ) =χa(x ) [v0(x ) +v1(x ) ei α y] , where χa(x ) :=1 for x ∈[0 ,a ] , χa(x ) :=0 for x ∉[0 ,a ] , vj(x ) are real or complex-valued functions, χa(x ) v0(x ) is an exactly solvable scattering potential in one dimension, and α is a positive real parameter. If α exceeds the wave number k of the incident wave, the scattered wave does not depend on the choice of v1(x ) . In particular, v (x ,y ) is invisible if v0(x ) =0 and k α and v1(x ) ≠0 , the scattered wave consists of a finite number of coherent plane-wave pairs ψn± with wave vector: kn=(±√{k2-[nα ] 2 },n α ) , where n =0 ,1 ,2 ,...scattering of wave packets and suggests means for generating quantum states with a quantized component of momentum and pairs of states with an entangled momentum. We examine a realization of these potentials in terms of certain optical slabs. If k =N α for some positive integer N , ψN± coalesce and their amplitude diverge. If k exceeds N α slightly, ψN± have a much larger amplitude than ψn± with n effect that arises for the scattered waves whose wave vector makes a small angle with the faces of the slab.

  2. Bidirectional optical scattering facility (United States)

    Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI)The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from a...

  3. K sup + - scattering

    CERN Document Server

    Farhan, A M


    A prescription is given to construct an effective interaction that may describe the scattering of K sup + by spin-zero nuclei in a more reliable way. This prescription is based on the Lorentz invariant representation of the meson-nucleon amplitude and the use of the Klein-Gordon equation of motion. Good results for K sup + - sup 1 sup 2 C as well as K sup + - D total cross sections at various energies have been obtained. (author)

  4. Vibrational effects in x-ray absorption and resonant inelastic x-ray scattering using a semiclassical scheme (United States)

    Ljungberg, Mathias P.


    A method is presented for describing vibrational effects in x-ray absorption spectroscopy and resonant inelastic x-ray scattering (RIXS) using a combination of the classical Franck-Condon (FC) approximation and classical trajectories run on the core-excited state. The formulation of RIXS is an extension of the semiclassical Kramers-Heisenberg formalism of Ljungberg et al. [Phys. Rev. B 82, 245115 (2010), 10.1103/PhysRevB.82.245115] to the resonant case, retaining approximately the same computational cost. To overcome difficulties with connecting the absorption and emission processes in RIXS, the classical FC approximation is used for the absorption, which is seen to work well provided that a zero-point-energy correction is included. In the case of core-excited states with dissociative character, the method is capable of closely reproducing the main features for one-dimensional test systems, compared to the quantum-mechanical formulation. Due to the good accuracy combined with the relatively low computational cost, the method has great potential of being used for complex systems with many degrees of freedom, such as liquids and surface adsorbates.

  5. Finite-size effects on the lattice dynamics in spin crossover nanomaterials. I. Nuclear inelastic scattering investigation (United States)

    Mikolasek, Mirko; Félix, Gautier; Peng, Haonan; Rat, Sylvain; Terki, Férial; Chumakov, Aleksandr I.; Salmon, Lionel; Molnár, Gábor; Nicolazzi, William; Bousseksou, Azzedine


    We report the investigation of the size evolution of lattice dynamics in spin crossover coordination nanoparticles of [ Fe (pyrazine ) (Ni (CN) 4) ] through nuclear inelastic scattering (NIS) measurements. Vibrational properties in these bistable molecular materials are of paramount importance and NIS permits access to the partial vibrational density of states in both spin states [high spin (HS) and low spin (LS)] from which thermodynamical and mechanical properties can be extracted. We show that the size reduction leads to the presence of inactive metal centers with the coexistence of HS and LS vibrational modes. The confinement effect has only weak impact on the vibrational properties of nanoparticles, especially on the optical modes which remain almost unchanged. On the other hand, the acoustic modes are much more affected which results in the increase of the vibrational entropy and also the Debye sound velocity in the smallest particles (spin states. This stiffening may be due to the elastic surface stress exerted by the external environment. An evidence of the influence of the host matrix on the vibrational properties of the nanoparticles is also highlighted through the matrix dependence of the sound velocity.

  6. Effects of moderate pump and Stokes chirp on chirped-probe pulse femtosecond coherent anti-Stokes Raman scattering thermometry

    KAUST Repository

    Gu, Mingming


    The effects of moderate levels of chirp in the pump and Stokes pulses on chirped-probe-pulse femtosecond coherent anti-Stokes Raman scattering (CPP fs CARS) were investigated. The frequency chirp in the pump and Stokes pulses was introduced by placing SF11 glass disks with thicknesses of 10 mm or 20 mm in the optical path for these beams. The magnitude of the chirp in the probe beam was much greater and was induced by placing a 30-cm rod of SF10 glass in the beam path. The temperature measurements were performed in hydrogen/air non-premixed flames stabilized on a Hencken burner at equivalence ratios of 0.3, 0.5, 0.7, and 1.0. We performed measurements with no disks in pump and Stokes beam paths, and then with disks of 10 mm and 20 mm placed in both beam paths. The spectrum of the nonresonant background four-wave mixing signal narrowed considerably with increasing pump and Stokes chirp, while the resonant CARS signal was relatively unaffected. Consequently, the interference of the nonresonant background with the resonant CARS signal in the frequency-spread dephasing region of the spectrum was minimized. The increased rate of decay of the resonant CARS signal with increasing temperature was thus readily apparent. We have started to analyze the CPP fs CARS thermometry data and initial results indicate improved accuracy and precision are obtained due to moderate chirp in the pump and Stokes laser pulses.

  7. Cooperative scattering of scalar waves by optimized configurations of point scatterers (United States)

    Schäfer, Frank; Eckert, Felix; Wellens, Thomas


    We investigate multiple scattering of scalar waves by an ensemble of N resonant point scatterers in three dimensions. For up to N = 21 scatterers, we numerically optimize the positions of the individual scatterers, to maximize the total scattering cross section for an incoming plane wave, on the one hand, and to minimize the decay rate associated to a long-lived scattering resonance, on the other. In both cases, the optimum is achieved by configurations where all scatterers are placed on a line parallel to the direction of the incoming plane wave. The associated maximal scattering cross section increases quadratically with the number of scatterers for large N, whereas the minimal decay rate—which is realized by configurations that are not the same as those that maximize the scattering cross section—decreases exponentially as a function of N. Finally, we also analyze the stability of our optimized configurations with respect to small random displacements of the scatterers. These results demonstrate that optimized configurations of scatterers bear a considerable potential for applications such as quantum memories or mirrors consisting of only a few atoms.

  8. Effective atomic number of some sugars and amino acids for scattering of (241)Am and (137)Cs gamma rays at low momentum transfer. (United States)

    Vinaykumar, L; Umesh, T K


    In this paper, we report the effective atomic number of some H, C, N and O based sugars and amino acids. These have been determined by using a handy expression which is based on the theoretical angle integrated small angle (coherent+incoherent) scattering cross sections of seven elements of Z≤13 in four angular ranges of (0-4°), (0-6°), (0-8°) and (0-10°)for (241)Am (59.54 keV) and (137)Cs (661.6 keV) gamma rays. The theoretical scattering cross sections were computed by a suitable numerical integration of the atomic form factor and incoherent scattering function compilations of Hubbell et al. (1975) which make use of the non-relativistic Hartree-Fock (NRHF) model for the atomic charge distribution of the elements in the angular ranges of interest. The angle integrated small angle scattering cross sections of the H, C, N and O based sugars and amino acids measured by a new method reported recently by the authors were used in the handy expression to derive their effective atomic number. The results are compared with the other available data and discussed. Possible conclusions are drawn based on the present study. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Effect of Reducing Indoor Air Pollution on Women's Respiratory Symptoms and Lung Function: The RESPIRE Randomized Trial, Guatemala

    National Research Council Canada - National Science Library

    Smith-Sivertsen, Tone; Díaz, Esperanza; Pope, Dan; Lie, Rolv T; Díaz, Anaite; McCracken, John; Bakke, Per; Arana, Byron; Smith, Kirk R; Bruce, Nigel


    .... The Randomized Exposure Study of Pollution Indoors and Respiratory Effects (RESPIRE) is a randomized intervention trial evaluating the respiratory health effects of reducing indoor air pollution from open cooking fires...

  10. [Effects of high-strip density anti-scatter grid on image quality and radiation dose]. (United States)

    Wamser, G; Maier, W; Aichinger, H; Bohndorf, K


    Using a new type of a stationary high strip density grid (13/75) for plain films of the abdomen, the effect was evaluated with regard to quality and patient dose in comparison with an established moving radiographic grid (12/40). The high strip density grid (13/75) was compared with a 12/40 grid using test objects and 100 patients per each grid type for plain films of the abdomen. The examinations were carried out via the screen-film system, speed class (SC) 400. Patients' weight, age and dose measurements were recorded. The image quality was evaluated via a multi-reader study using delineation of anatomical structures and a rating scale (score 1-5 or 1-3). Both measurements with test objects and patients abdominal plain films showed a decrease in radiation dose of 17% using the 13/75 grid, and 24%, respectively. The delineation of 4 out of 7 anatomical structures was slightly reduced with the new high strip density grid (maximum score reduction: 0.4), the image contrast, as well as the radiologists' subjective rating. Apart from an acceptable loss in image quality compared with the 12/40 grid, the new high strip density grid (13/ 75) enables a clear reduction in radiation dose.


    Directory of Open Access Journals (Sweden)



    Full Text Available Here, of great interest to us is a quantitative study of the scattering properties from ramified polymeric systems of arbitrary topology. We consider three types of systems, namely ramified polymers in solution, ramified polymer blends, or ternary mixtures made of two ramified polymers of different chemical nature immersed in a good solvent. To achieve the goal of the study, use is made of the Random Phase Approximation. First we determine the exact expression of the form factor of an ideal ramified polymer of any topology, from which we extract the exact expression of its gyration radius. Using the classical Zimm's formulae and the exact form factor, we determine all scattering properties of these three types of ramified polymeric systems. The main conclusion is that ramification of the chains induces drastic changes of the scattering properties.

  12. On the inversion of the scattering polarization and the Hanle effect signals in the hydrogen Lyα line

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, R. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Asensio Ramos, A.; Manso Sainz, R.; Trujillo Bueno, J. [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain); Belluzzi, L. [Istituto Ricerche Solari Locarno (IRSOL), via Patocchi, 6605 Locarno Monti (Switzerland); Štěpán, J. [Astronomical Institute of the Academy of Sciences, Fričova 298, 251 65 Ondřejov (Czech Republic); Goto, M. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Tsuneta, S., E-mail: [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan)


    Magnetic field measurements in the upper chromosphere and above, where the gas-to-magnetic pressure ratio β is lower than unity, are essential for understanding the thermal structure and dynamical activity of the solar atmosphere. Recent developments in the theory and numerical modeling of polarization in spectral lines have suggested that information on the magnetic field of the chromosphere-corona transition region could be obtained by measuring the linear polarization of the solar disk radiation at the core of the hydrogen Lyα line at 121.6 nm, which is produced by scattering processes and the Hanle effect. The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) sounding rocket experiment aims to measure the intensity (Stokes I) and the linear polarization profiles (Q/I and U/I) of the hydrogen Lyα line. In this paper, we clarify the information that the Hanle effect can provide by applying a Stokes inversion technique based on a database search. The database contains all theoretical Q/I and U/I profiles calculated in a one-dimensional semi-empirical model of the solar atmosphere for all possible values of the strength, inclination, and azimuth of the magnetic field vector, though this atmospheric region is highly inhomogeneous and dynamic. We focus on understanding the sensitivity of the inversion results to the noise and spectral resolution of the synthetic observations as well as the ambiguities and limitation inherent to the Hanle effect when only the hydrogen Lyα is used. We conclude that spectropolarimetric observations with CLASP can indeed be a suitable diagnostic tool for probing the magnetism of the transition region, especially when complemented with information on the magnetic field azimuth that can be obtained from other instruments.

  13. Antiarrhythmic effect of statin therapy and atrial fibrillation a meta-analysis of randomized controlled trials

    National Research Council Canada - National Science Library

    Fauchier, Laurent; Pierre, Bertrand; de Labriolle, Axel; Grimard, Caroline; Zannad, Noura; Babuty, Dominique


    To improve the evaluation of the possible antiarrhythmic effect of statins, we performed a meta-analysis of randomized trials with statins on the end point of incidence or recurrence of atrial fibrillation (AF...

  14. The effects of motivation feedback in patients with severe mental illness : A cluster randomized controlled trial

    NARCIS (Netherlands)

    Jochems, E.C.; van der Feltz-Cornelis, C.M.; van Dam, A.; Duivenvoorden, H.J.; Mulder, C.L.


    Objective: To evaluate the effectiveness of providing clinicians with regular feedback on the patient’s motivation for treatment in increasing treatment engagement in patients with severe mental illness. Methods: Design: cluster randomized controlled trial (Dutch Trials Registry NTR2968).

  15. Rgbp: An R Package for Gaussian, Poisson, and Binomial Random Effects Models with Frequency Coverage Evaluations

    Directory of Open Access Journals (Sweden)

    Hyungsuk Tak


    Full Text Available Rgbp is an R package that provides estimates and verifiable confidence intervals for random effects in two-level conjugate hierarchical models for overdispersed Gaussian, Poisson, and binomial data. Rgbp models aggregate data from k independent groups summarized by observed sufficient statistics for each random effect, such as sample means, possibly with covariates. Rgbp uses approximate Bayesian machinery with unique improper priors for the hyper-parameters, which leads to good repeated sampling coverage properties for random effects. A special feature of Rgbp is an option that generates synthetic data sets to check whether the interval estimates for random effects actually meet the nominal confidence levels. Additionally, Rgbp provides inference statistics for the hyper-parameters, e.g., regression coefficients.

  16. Two-Photon Exchange Effects in Elastic Electron-Proton Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Myriam James [Argonne National Lab. (ANL), Argonne, IL (United States)


    Two methods, Rosenbluth separation and polarization transfer, can be used to extract the proton form factor ratio μp GEp/GMp, but they do not yield the same results. It is thought that the disagreement is due to two photon exchange corrections to the differential cross sections. High precision proton Rosenbluth extractions were carried out at 102 kinematics points spanning 16 values of momentum transfer Q2, from 0.40 to 5.76 GeV2. Reduced cross sections were found to 1.1% or better for Q2 less than 3 GeV2 increasing to 4% at 5.76 GeV2 The form factor ratios were determined to 1:5-3% for Q2 < 1.5 GeV2, increasing to 9% by 3 GeV2 and rapidly above. Our data agrees with prior Rosenbluth, improving upon it the 1.0 - 2.0 GeV2 range to conclusively show a separation from polarization transfer where it had not been certain before. In addition, reduced cross sections at each Q2 were tested for nonlinearity in the angular variable. Such a departure from linearity would be a signature of two photon exchange effects, and prior data had not been sufficiently precise to show nonzero curvature. Our data begins to hint at negative curvature but does not yet show a significant departure from zero.

  17. Positronium and Electron Scattering on Helium (United States)

    DiRienzi, Joseph


    A recent work [1] establishes experimentally that Positronium scattering by atoms of various elements is surprisingly close in total cross-section to that of an isolated electron of the same velocity. In this work we will look at the scattering of Ps on Helium and compare it to a determination of the scattering of an e- with the same element. For both the Ps scattering and the e- scattering on He, we assume the symmetrization of the e- with the closed shell He electrons is the dominant interaction. A local effective potential employed in [2] and [3] is used to model the electron exchange and cross- sections are determined for a set of partial waves. For the Ps scattering we include as a secondary effect the Van der Waals interaction. For single e- scattering of He, we also employ a short range Coulomb potential and dispersion as contributing effects. Results of the cross-sections determined in each case are then compared



    Liu, Xian; Engel, Charles C.


    Researchers often encounter longitudinal health data characterized with three or more ordinal or nominal categories. Random-effects multinomial logit models are generally applied to account for potential lack of independence inherent in such clustered data. When parameter estimates are used to describe longitudinal processes, however, random effects, both between and within individuals, need to be retransformed for correctly predicting outcome probabilities. This study attempts to go beyond e...

  19. Variance of phase fluctuations of waves propagating through a random medium (United States)

    Chu, Nelson C.; Kong, Jin AU; Yueh, Simon H.; Nghiem, Son V.; Fleischman, Jack G.; Ayasli, Serpil; Shin, Robert T.


    As an electromagnetic wave propagates through a random scattering medium, such as a forest, its energy is attenuated and random phase fluctuations are induced. The magnitude of the random phase fluctuations induced is important in estimating how well a Synthetic Aperture Radar (SAR) can image objects within the scattering medium. The two-layer random medium model, consisting of a scattering layer between free space and ground, is used to calculate the variance of the phase fluctuations induced between a transmitter located above the random medium and a receiver located below the random medium. The scattering properties of the random medium are characterized by a correlation function of the random permittivity fluctuations. The effective permittivity of the random medium is first calculated using the strong fluctuation theory, which accounts for large permittivity fluctuations of the scatterers. The distorted Born approximation is used to calculate the first-order scattered field. A perturbation series for the phase of the received field in the Rytov approximation is then introduced and the variance of the phase fluctuations is also calculated assuming that the transmitter and receiver are in the paraxial limit of the random medium, which allows an analytic solution to be obtained. Results are compared using the paraxial approximation, scalar Green's function formulation, and dyadic Green's function formulation. The effects studied are the dependence of the variance of the phase fluctuations on receiver location in lossy and lossless regions, medium thickness, correlation length and fractional volume of scatterers, depolarization of the incident wave, ground layer permittivity, angle of incidence, and polarization.

  20. Reproducibility of artificial multiple scattering media

    NARCIS (Netherlands)

    Marakis, Evangelos; van Harten, Wouter; Uppu, Ravitej; Pinkse, Pepijn Willemszoon Harry


    State of the art authentication systems depend on physical unclonable functions (PUF) [1], physical keys that are assumed unclonable due to technological constraints. Random scattering media, dielectric materials with rapid and random refractive index variations, are considered as ideal optical PUFs

  1. A random effects meta-analysis model with Box-Cox transformation. (United States)

    Yamaguchi, Yusuke; Maruo, Kazushi; Partlett, Christopher; Riley, Richard D


    In a random effects meta-analysis model, true treatment effects for each study are routinely assumed to follow a normal distribution. However, normality is a restrictive assumption and the misspecification of the random effects distribution may result in a misleading estimate of overall mean for the treatment effect, an inappropriate quantification of heterogeneity across studies and a wrongly symmetric prediction interval. We focus on problems caused by an inappropriate normality assumption of the random effects distribution, and propose a novel random effects meta-analysis model where a Box-Cox transformation is applied to the observed treatment effect estimates. The proposed model aims to normalise an overall distribution of observed treatment effect estimates, which is sum of the within-study sampling distributions and the random effects distribution. When sampling distributions are approximately normal, non-normality in the overall distribution will be mainly due to the random effects distribution, especially when the between-study variation is large relative to the within-study variation. The Box-Cox transformation addresses this flexibly according to the observed departure from normality. We use a Bayesian approach for estimating parameters in the proposed model, and suggest summarising the meta-analysis results by an overall median, an interquartile range and a prediction interval. The model can be applied for any kind of variables once the treatment effect estimate is defined from the variable. A simulation study suggested that when the overall distribution of treatment effect estimates are skewed, the overall mean and conventional I 2 from the normal random effects model could be inappropriate summaries, and the proposed model helped reduce this issue. We illustrated the proposed model using two examples, which revealed some important differences on summary results, heterogeneity measures and prediction intervals from the normal random effects model. The

  2. Rayleigh's Scattering Revised (United States)

    Kolomiets, Sergey; Gorelik, Andrey

    Mie’s waves while sounding within coincident volumes. Being sensitive to the size of scatters, Mie’s waves can give us additional information about particle size distribution. But how about using several wavelengths corresponding to Rayleigh’s diffraction on scatters only? Can any effects be detected in such a case and what performance characteristics of the equipment are required to detect them? The deceptive simplicity of the negative answer to the first part of the question posed will disappear if one collects different definitions of Rayleigh's scattering and consider them more closely than usually. Several definitions borrowed from the introductory texts and most popular textbooks and articles can be seen as one of the reasons for the research presented in the report. Hopefully, based on the comparison of them all, anyone could easily conclude that Rayleigh's scattering has been analyzed extensively, but despite this extensive analysis made fundamental ambiguities in introductory texts are not eliminated completely to date. Moreover, there may be found unreasonably many examples on how these ambiguities have already caused an error to be foreseen, published on the one article, amplified in another one, then cited with approval in the third one, before being finally corrected. Everything indicated that in the light of all the lesions learned and based on modern experimental data, it is time to address these issues again. After the discussion of ambiguities of Rayleigh's scattering concepts, the development of the corrections to original ideas looks relatively easy. In particular, there may be distinguished at least three characteristic regions of the revised models application from the point of view of the scattered field statistical averaging. The authors of the report suggest naming them Rayleigh’s region, Einstein’s region and the region with compensations of the scattering intensity. The most important fact is that the limits of applicability of all

  3. Can we apply the Mendelian randomization methodology without considering epigenetic effects?

    Directory of Open Access Journals (Sweden)

    Karmaus Wilfried


    Full Text Available Abstract Introduction Instrumental variable (IV methods have been used in econometrics for several decades now, but have only recently been introduced into the epidemiologic research frameworks. Similarly, Mendelian randomization studies, which use the IV methodology for analysis and inference in epidemiology, were introduced into the epidemiologist's toolbox only in the last decade. Analysis Mendelian randomization studies using instrumental variables (IVs have the potential to avoid some of the limitations of observational epidemiology (confounding, reverse causality, regression dilution bias for making causal inferences. Certain limitations of randomized controlled trials, such as problems with generalizability, feasibility and ethics for some exposures, and high costs, also make the use of Mendelian randomization in observational studies attractive. Unlike conventional randomized controlled trials (RCTs, Mendelian randomization studies can be conducted in a representative sample without imposing any exclusion criteria or requiring volunteers to be amenable to random treatment allocation. Within the last decade, epigenetics has gained recognition as an independent field of study, and appears to be the new direction for future research into the genetics of complex diseases. Although previous articles have addressed some of the limitations of Mendelian randomization (such as the lack of suitable genetic variants, unreliable associations, population stratification, linkage disequilibrium (LD, pleiotropy, developmental canalization, the need for large sample sizes and some potential problems with binary outcomes, none has directly characterized the impact of epigenetics on Mendelian randomization. The possibility of epigenetic effects (non-Mendelian, heritable changes in gene expression not accompanied by alterations in DNA sequence could alter the core instrumental variable assumptions of Mendelian randomization. This paper applies conceptual

  4. FDTD Analysis of Spatial Filtering of Scattered Waves for Optical CT of Medical Diagnosis (United States)

    Miyazaki, Yasumitsu; Kouno, Kouhei

    Medical image diagnosis and computer aided diagnosis are modern important medical techniques developed with computer technology. Particularly, medical image diagnosis using optical waves of lasers is very important technical tools for physiological examination of human body. Transmission properties mainly depend on optical absorption effects due to biological characteristics consisting of atomic and molecular structures. Image responses of optical transmitted projection include optical scattering characteristics that disturb transmission properties through biological structures. Computer numerical simulations of spatial filtering for optical scattering waves superposed on transmitted and attenuated waves are discussed to improve image diagnosis. By numerical simulation of FDTD method, statistical characteristics of optical waves are discussed for optical propagation, attenuation and scattering in random inhomogeneous biological media that consist of random particle models given by random numbers programming. Spatial filtering characteristics of grid structure are shown for exact image optical projection excluding scattering effects through physiological media. Spatial filtering characteristics for off-axial scattering optical waves are graphically shown by propagation properties with large attenuation in lossy waveguide-type grids by FDTD method.

  5. Random matrices

    CERN Document Server

    Mehta, Madan Lal


    Since the publication of Random Matrices (Academic Press, 1967) so many new results have emerged both in theory and in applications, that this edition is almost completely revised to reflect the developments. For example, the theory of matrices with quaternion elements was developed to compute certain multiple integrals, and the inverse scattering theory was used to derive asymptotic results. The discovery of Selberg's 1944 paper on a multiple integral also gave rise to hundreds of recent publications. This book presents a coherent and detailed analytical treatment of random matrices, leading

  6. Scattering problems in elastodynamics

    CERN Document Server

    Diatta, Andre; Wegener, Martin; Guenneau, Sebastien


    In electromagnetism, acoustics, and quantum mechanics, scattering problems can routinely be solved numerically by virtue of perfectly matched layers (PMLs) at simulation domain boundaries. Unfortunately, the same has not been possible for general elastodynamic wave problems in continuum mechanics. In this paper, we introduce a corresponding scattered-field formulation for the Navier equation. We derive PMLs based on complex-valued coordinate transformations leading to Cosserat elasticity-tensor distributions not obeying the minor symmetries. These layers are shown to work in two dimensions, for all polarizations, and all directions. By adaptative choice of the decay length, the deep subwavelength PMLs can be used all the way to the quasi-static regime. As demanding examples, we study the effectiveness of cylindrical elastodynamic cloaks of the Cosserat type and approximations thereof.

  7. Effects of multiple scatter on the propagation and absorption of electromagnetic waves in a field-aligned-striated cold magneto-plasma: implications for ionospheric modification experiments

    Directory of Open Access Journals (Sweden)

    T. R. Robinson

    Full Text Available A new theory of the propagation of low power electromagnetic test waves through the upper-hybrid resonance layer in the presence of magnetic field-aligned plasma density striations, which includes the effects of multiple scatter, is presented. The case of sinusoidal striations in a cold magnetoplasma is treated rigorously and then extended, in an approximate manner, to the broad-band striation spectrum and warm plasma cases. In contrast to previous, single scatter theories, it is found that the interaction layer is much broader than the wavelength of the test wave. This is due to the combined electric fields of the scattered waves becoming localised on the contour of a fixed plasma density, which corresponds to a constant value for the local upper-hybrid resonance frequency over the whole interaction region. The results are applied to the calculation of the refractive index of an ordinary mode test wave during modification experiments in the ionospheric F-region. Although strong anomalous absorption arises, no new cutoffs occur at the upper-hybrid resonance, so that in contrast to the predictions of previous single scatter theories, no additional reflections occur there. These results are consistent with observations made during ionospheric modification experiments at Tromsø, Norway.

    Key words. Ionosphere (active experiments; ionospheric irregularities Radio science (ionospheric propagation

  8. Sodium dodecyl sulfate (SDS) effect on the thermal stability of oxy-HbGp: dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) studies. (United States)

    Carvalho, José Wilson P; Alves, Fernanda Rosa; Batista, Tatiana; Carvalho, Francisco Adriano O; Santiago, Patrícia S; Tabak, Marcel


    Glossoscolex paulistus (HbGp) hemoglobin is an oligomeric protein, presenting a quaternary structure constituted by 144 globin and 36 non-globin chains (named linkers) with a total molecular mass of 3.6 MDa. SDS effects on the oxy-HbGp thermal stability were studied, by DLS and SAXS, at pH 5.0, 7.0 and 9.0. DLS and SAXS data show that the SDS-oxy-HbGp interactions induce a significant decrease of the protein thermal stability, with the formation of larger aggregates, at pH 5.0. At pH 7.0, oxy-HbGp undergoes complete oligomeric dissociation, with increase of temperature, in the presence of SDS. Besides, oxy-HbGp 3.0mg/mL, pH 7.0, in the presence of SDS, has the oligomeric dissociation process reduced as compared to 0.5mg/mL of protein. At pH 9.0, oxy-HbGp starts to dissociate at 20 °C, and the protein is totally dissociated at 50 °C. The thermal dissociation kinetic data show that oxy-HbGp oligomeric dissociation at pH 7.0, in the presence of SDS, is strongly dependent on the protein concentration. At 0.5mg/mL of protein, the oligomeric dissociation is complete and fast at 40 and 42 °C, with kinetic constants of (2.1 ± 0.2) × 10(-4) and (5.5 ± 0.4) × 10(-4) s(-1), respectively, at 0.6 mmol/L SDS. However, at 3.0mg/mL, the oligomeric dissociation process starts at 46 °C, and only partial dissociation, accompanied by aggregates formation is observed. Moreover, our data show, for the first time, that, for 3.0mg/mL of protein, the oligomeric dissociation, denaturation and aggregation phenomena occur simultaneously, in the presence of SDS. Our present results on the surfactant-HbGp interactions and the protein thermal unfolding process correspond to a step forward in the understanding of SDS effects. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Cost-effectiveness of online positive psychology: Randomized controlled trial

    NARCIS (Netherlands)

    Bolier, Linda; Majo, Cristina; Smit, Filip; Westerhof, Gerben Johan; Haverman, Merel; Walburg, J.A.; Riper, Heleen; Bohlmeijer, Ernst Thomas


    As yet, no evidence is available about the cost-effectiveness of positive psychological interventions. When offered via the Internet, these interventions may be particularly cost-effective, because they are highly scalable and do not rely on scant resources such as therapists’ time. Alongside a

  10. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)


    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  11. Semi-parametric estimation of random effects in a logistic regression model using conditional inference

    DEFF Research Database (Denmark)

    Petersen, Jørgen Holm


    This paper describes a new approach to the estimation in a logistic regression model with two crossed random effects where special interest is in estimating the variance of one of the effects while not making distributional assumptions about the other effect. A composite likelihood is studied...

  12. Bounding the per-protocol effect in randomized trials: An application to colorectal cancer screening

    NARCIS (Netherlands)

    S.A. Swanson (Sonja); Holme (Øyvind); M. Løberg (Magnus); M. Kalager (Mette); M. Bretthauer (Michael); G. Hoff (G.); E. Aas (Eline); M.A. Hernán (M.)


    textabstractBackground: The per-protocol effect is the effect that would have been observed in a randomized trial had everybody followed the protocol. Though obtaining a valid point estimate for the per-protocol effect requires assumptions that are unverifiable and often implausible, lower and upper

  13. The random effects prep continues to mispredict the probability of replication

    NARCIS (Netherlands)

    Iverson, G.J.; Lee, M.D.; Wagenmakers, E.-J.


    In their reply, Lecoutre and Killeen (2010) argue for a random effects version of prep, in which the observed effect from one experiment is used to predict the probability that an effect from a different but related experiment will have the same sign. They present a figure giving the impression that

  14. Light Scattering Spectroscopy: From Elastic to Inelastic (United States)

    Perelman, Lev T.; Modell, Mark D.; Vitkin, Edward; Hanlon, Eugene B.

    This chapter reviews light scattering spectroscopic techniques in which coherent effects are critical because they define the structure of the spectrum. In the case of elastic light scattering spectroscopy, the targets themselves, such as aerosol particles in environmental science or cells and subcellular organelles in biomedical applications, play the role of microscopic optical resonators. In the case of inelastic light scattering spectroscopy or Raman spectroscopy, the spectrum is created due to light scattering from vibrations in molecules or optical phonons in solids. We will show that light scattering spectroscopic techniques, both elastic and inelastic, are emerging as very useful tools in material and environmental science and in biomedicine.

  15. The effect of the electron scattering phase shifts upon the computational outcomes of the Low-Energy Electron Diffraction technique (United States)

    Adas, Sonya; Meyers, Lisa; Caragiu, Mellita


    In a typical Low-Energy Electron Diffraction (LEED) investigation of a crystal surface, the electrons probing the surface are scattered by the atoms in the sample. The scattering process introduces phase shifts in the waves associated to the incoming electrons. An investigation of how these phase shifts influence the results of a LEED calculation are presented for the fairly complicated Cu(511) stepped surface. The phase shifts have been calculated using the Barbieri/Van Hove Phase Shift Package. The phase shifts considered correspond to copper atoms arranged in various planes of the copper crystal: (100), (111), and a close approximation of the (511) plane.

  16. Effects of an eccentric inner Jupiter on the dynamical evolution of icy body reservoirs in a planetary scattering scenario (United States)

    Zanardi, M.; de Elía, G. C.; Di Sisto, R. P.; Naoz, S.; Li, G.; Guilera, O. M.; Brunini, A.


    Aims: We analyze the dynamics of small body reservoirs under the effects of an eccentric inner giant planet resulting from a planetary scattering event around a 0.5 M⊙ star. Methods: First, we used a semi-analytical model to define the properties of the protoplanetary disk that lead to the formation of three Jupiter-mass planets. Then, we carried out N-body simulations assuming that the planets are close to their stability limit together with an outer planetesimal disk. In particular, the present work focused on the analysis of N-body simulations in which a single Jupiter-mass planet survives after the dynamical instability event. Results: Our simulations produce outer small body reservoirs with particles on prograde and retrograde orbits, and other ones whose orbital plane flips from prograde to retrograde and back again along their evolution ("Type-F particles"). We find strong correlations between the inclination i and the ascending node longitude Ω of Type-F particles. First, Ω librates around 90° or/and 270°. This property represents a necessary and sufficient condition for the flipping of an orbit. Moreover, the libration periods of i and Ω are equal and they are out to phase by a quarter period. We also remark that the larger the libration amplitude of i, the larger the libration amplitude of Ω. We analyze the orbital parameters of Type-F particles immediately after the instability event (post IE orbital parameters), when a single Jupiter-mass planet survives in the system. Our results suggest that the orbit of a particle can flip for any value of its post IE eccentricity, although we find only two Type-F particles with post IE inclinations i ≲ 17°. Finally, our study indicates that the minimum value of the inclination of the Type-F particles in a given system decreases with an increase in the eccentricity of the giant planet.

  17. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)


    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  18. Scattering matrix measurements and light-scattering calculations of calcite particles

    Directory of Open Access Journals (Sweden)

    D. D. Dabrowska


    Full Text Available We present measurements of the complete scattering matrix as a function of the scattering angle of a sample of calcite particles collected near Lecce, Italy. The measurements are done at a wavelength of 647 nm in the scattering angle range 3°−177°. FESEM and SEM images show that the sample consists largely of flake-like particles. Ten different flake-like geometries are randomly generated and their scattering properties are simulated with DDA for sizes from 0.1 μm to 1 μm. Some preliminary comparisons of the simulations and the measurements are shown.

  19. Generalized two-dimensional (2D) linear system analysis metrics (GMTF, GDQE) for digital radiography systems including the effect of focal spot, magnification, scatter, and detector characteristics. (United States)

    Jain, Amit; Kuhls-Gilcrist, Andrew T; Gupta, Sandesh K; Bednarek, Daniel R; Rudin, Stephen


    The MTF, NNPS, and DQE are standard linear system metrics used to characterize intrinsic detector performance. To evaluate total system performance for actual clinical conditions, generalized linear system metrics (GMTF, GNNPS and GDQE) that include the effect of the focal spot distribution, scattered radiation, and geometric unsharpness are more meaningful and appropriate. In this study, a two-dimensional (2D) generalized linear system analysis was carried out for a standard flat panel detector (FPD) (194-micron pixel pitch and 600-micron thick CsI) and a newly-developed, high-resolution, micro-angiographic fluoroscope (MAF) (35-micron pixel pitch and 300-micron thick CsI). Realistic clinical parameters and x-ray spectra were used. The 2D detector MTFs were calculated using the new Noise Response method and slanted edge method and 2D focal spot distribution measurements were done using a pin-hole assembly. The scatter fraction, generated for a uniform head equivalent phantom, was measured and the scatter MTF was simulated with a theoretical model. Different magnifications and scatter fractions were used to estimate the 2D GMTF, GNNPS and GDQE for both detectors. Results show spatial non-isotropy for the 2D generalized metrics which provide a quantitative description of the performance of the complete imaging system for both detectors. This generalized analysis demonstrated that the MAF and FPD have similar capabilities at lower spatial frequencies, but that the MAF has superior performance over the FPD at higher frequencies even when considering focal spot blurring and scatter. This 2D generalized performance analysis is a valuable tool to evaluate total system capabilities and to enable optimized design for specific imaging tasks.

  20. Controlling Radiative Heat Transfer Across the Mold Flux Layer by the Scattering Effect of the Borosilicate Mold Flux System with Metallic Iron (United States)

    Yoon, Dae-Woo; Cho, Jung-Wook; Kim, Seon-Hyo


    The present study proposes a countermeasure for regulating total heat flux through the mold flux layer by designed mold flux with additive metallic iron particles. The heat flux through the B2O3-CaO-SiO2-Na2O-CaF2-Fe system was investigated using the infrared emitter technique to evaluate total flux density across the mold flux film. Both scanning electron microscope (SEM) and X-ray diffraction analysis were employed in order to identify the morphological and compositional changes of the crystalline phase, according to increasing iron contents in the mold flux. It was confirmed that the crystalline layer of studied mold fluxes does not have a meaningful effect on the total heat flux density due to the similar structure and fraction of the crystalline phase. The extinction coefficient was measured for glassy mold fluxes using an ultraviolet/visible and a Fourier transformation-infrared ray spectrometer in the range of 0.5 to 5 μm. For analyzing the scattering behavior of iron particles on the extinction coefficient, the number density and diameter of particles were observed by an automated SEM (auto-SEM). With these data, Mie scattering theory is adopted to define the scattering behavior of dispersed iron droplets in glassy matrix. It was found that the theoretical scattering coefficient demonstrated about 1623 to 3295 m-1, which is in accordance with the experimental results. In doing so, this study successfully achieves the strong scattering behavior that would contribute greatly to the optimization of overall heat flux through the mold flux film during the casting process.