Ultrasound scatter in heterogeneous 3D microstructures: Parameters affecting multiple scattering
Engle, B. J.; Roberts, R. A.; Grandin, R. J.
2018-04-01
This paper reports on a computational study of ultrasound propagation in heterogeneous metal microstructures. Random spatial fluctuations in elastic properties over a range of length scales relative to ultrasound wavelength can give rise to scatter-induced attenuation, backscatter noise, and phase front aberration. It is of interest to quantify the dependence of these phenomena on the microstructure parameters, for the purpose of quantifying deleterious consequences on flaw detectability, and for the purpose of material characterization. Valuable tools for estimation of microstructure parameters (e.g. grain size) through analysis of ultrasound backscatter have been developed based on approximate weak-scattering models. While useful, it is understood that these tools display inherent inaccuracy when multiple scattering phenomena significantly contribute to the measurement. It is the goal of this work to supplement weak scattering model predictions with corrections derived through application of an exact computational scattering model to explicitly prescribed microstructures. The scattering problem is formulated as a volume integral equation (VIE) displaying a convolutional Green-function-derived kernel. The VIE is solved iteratively employing FFT-based con-volution. Realizations of random microstructures are specified on the micron scale using statistical property descriptions (e.g. grain size and orientation distributions), which are then spatially filtered to provide rigorously equivalent scattering media on a length scale relevant to ultrasound propagation. Scattering responses from ensembles of media representations are averaged to obtain mean and variance of quantities such as attenuation and backscatter noise levels, as a function of microstructure descriptors. The computational approach will be summarized, and examples of application will be presented.
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...
Scattering and multiple scattering in disordered materials
International Nuclear Information System (INIS)
Weaver, R.L.; Butler, W.H.
1992-01-01
The papers in this section were presented at a joint session of symposium V on Applications of Multiple Scattering Theory and of Symposium P on Disordered Systems. They show that the ideas of scattering theory can help us to understand a very broad class of phenomena
Determination of multiple scattering effects
International Nuclear Information System (INIS)
Langevin, M.
1981-01-01
The integration of Sigmund and Winterbon numerical values is extended to the reduced thickness tau=2000. The diagram obtained allows a simple determination of the multiple scattering effect for different targets and projectiles [fr
Effect of multiple scattering on lidar measurements
International Nuclear Information System (INIS)
Cohen, A.
1977-01-01
The lidar equation in its standard form involves the assumption that the scattered irradiance reaching the lidar receiver has been only singly scattered. However, in the cases of scattering from clouds and thick aerosol layers, it is shown that multiple scattering cannot be neglected. An experimental method for the detection of multiple scattering by depolarization measurement techniques is discussed. One method of theoretical calculations of double-scattering is presented and discussed
Spatial photon correlations in multiple scattering media
DEFF Research Database (Denmark)
Smolka, Stephan; Muskens, O.; Lagendijk, A.
2010-01-01
We present the first angle-resolved measurements of spatial photon correlations that are induced by multiple scattering of light. The correlation relates multiple scattered photons at different spatial positions and depends on incident photon fluctuations.......We present the first angle-resolved measurements of spatial photon correlations that are induced by multiple scattering of light. The correlation relates multiple scattered photons at different spatial positions and depends on incident photon fluctuations....
Gamma holography from multiple scattering
International Nuclear Information System (INIS)
Coussement, R.
2007-01-01
Since the introduction of heterodyne methods for synchrotron radiation (Cousesement et al. in Phys. Rev. B 54:16003, 1996; Callens et al. in Phys. Rev. 67:104423, 2003) one observes interferences between two scattering amplitudes; the scattering amplitude of resonant nuclei in a reference sample and the scattering amplitude of nuclei in the sample under investigation. Theses interferences can easily been observed as resonances in velocity spectra when one uses a time integrated method. They can also been observed as quantum beats, when one would use the time differential method. For both methods it is important that one uses a reference sample and therefore both methods disserved the name 'heterodyne methods.' As theses interferences are a product of two scattering amplitudes, the amplitude of a wave scattered form the investigated sample can be known with its phase. But it is assumed that the reference wave is known in advance by a proper choice of the reference sample. At first sight it is very likely that multiple scattering would add more complexity but in this paper it is claimed that on the contrary it provide a bonus, especially for single crystals. It provokes only a line broadening and a line shift of the resonances in the velocity spectra (or a change in the damping and frequency of the quantum beats when the time spectra are registered). Moreover these changes in the line shapes can easily be measured and they provide all the information needed to reconstruct a 3-D picture of the atomic arrangement of resonant nuclei and moreover they distinguish between different hyperfine sites. The method may be more practical for measurements on synchrotron radiation but it does also apply to velocity spectra obtained from resonant scattering with strong sources. The use of radioactive sources suffer from the disadvantage of poorer statistics or much longer accumulation times but they enjoy the advantage to be table-top and at-home experiments. As strong sources are
Thermal-neutron multiple scattering: critical double scattering
International Nuclear Information System (INIS)
Holm, W.A.
1976-01-01
A quantum mechanical formulation for multiple scattering of thermal-neutrons from macroscopic targets is presented and applied to single and double scattering. Critical nuclear scattering from liquids and critical magnetic scattering from ferromagnets are treated in detail in the quasielastic approximation for target systems slightly above their critical points. Numerical estimates are made of the double scattering contribution to the critical magnetic cross section using relevant parameters from actual experiments performed on various ferromagnets. The effect is to alter the usual Lorentzian line shape dependence on neutron wave vector transfer. Comparison with corresponding deviations in line shape resulting from the use of Fisher's modified form of the Ornstein-Zernike spin correlations within the framework of single scattering theory leads to values for the critical exponent eta of the modified correlations which reproduce the effect of double scattering. In addition, it is shown that by restricting the range of applicability of the multiple scattering theory from the outset to critical scattering, Glauber's high energy approximation can be used to provide a much simpler and more powerful description of multiple scattering effects. When sufficiently close to the critical point, it provides a closed form expression for the differential cross section which includes all orders of scattering and has the same form as the single scattering cross section with a modified exponent for the wave vector transfer
Depth distribution of multiple order X-ray scatter
International Nuclear Information System (INIS)
Yao Weiguang; Leszczynski, Konrad
2008-01-01
Scatter can significantly affect quality of projectional X-ray radiographs and tomographic reconstructions. With this in mind, we examined some of the physical properties of multiple orders of scatter of X-ray photons traversing through a layer of scattering media such as water. Using Monte Carlo techniques, we investigated depth distributions of interactions between incident X-ray photons and water before the resulting scattered photons reach the detector plane. Effects of factors such as radiation field size, air gap, thickness of the layer of scattering medium and X-ray energy, on the scatter were included in the scope of this study. The following scatter characteristics were observed: (1) for a layer of scattering material corresponding to the typical subject thickness in medical imaging, frequency distribution of locations of the last scattering interaction increases approximately exponentially with depth, and the higher the order of scatter or the energy of the incident photon, the narrower is the distribution; (2) for the second order scatter, the distribution of locations of the first interaction is more uniform than that of the last interaction and is dependent on the energy of the primary photons. Theoretical proofs for some of these properties are given. These properties are important to better understanding of effects of scatter on the radiographic and tomographic imaging process and to developing effective methods for scatter correction
Multiple scattering processes: inverse and direct
International Nuclear Information System (INIS)
Kagiwada, H.H.; Kalaba, R.; Ueno, S.
1975-01-01
The purpose of the work is to formulate inverse problems in radiative transfer, to introduce the functions b and h as parameters of internal intensity in homogeneous slabs, and to derive initial value problems to replace the more traditional boundary value problems and integral equations of multiple scattering with high computational efficiency. The discussion covers multiple scattering processes in a one-dimensional medium; isotropic scattering in homogeneous slabs illuminated by parallel rays of radiation; the theory of functions b and h in homogeneous slabs illuminated by isotropic sources of radiation either at the top or at the bottom; inverse and direct problems of multiple scattering in slabs including internal sources; multiple scattering in inhomogeneous media, with particular reference to inverse problems for estimation of layers and total thickness of inhomogeneous slabs and to multiple scattering problems with Lambert's law and specular reflectors underlying slabs; and anisotropic scattering with reduction of the number of relevant arguments through axially symmetric fields and expansion in Legendre functions. Gaussian quadrature data for a seven point formula, a FORTRAN program for computing the functions b and h, and tables of these functions supplement the text
Analysis of multiple scattering effects in optical Doppler tomography
DEFF Research Database (Denmark)
Yura, H.T.; Thrane, L.; Andersen, Peter E.
2005-01-01
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...... multiple scattering effects are included. The purpose of this analysis is to determine how multiple scattering affects the estimation of the depth-resolved localized flow velocity. Depth-resolved velocity estimates are obtained directly from the corresponding mean or standard deviation of the observed...
Multiple scattering of ions in polyatomic materials
International Nuclear Information System (INIS)
Eastham, D.A.
1980-01-01
The equations which determine small angle multiple scattering in the thin polyatomic layers are evaluated numerically for certain cases. A simple approximate method for calculating the scattering in terms of an average target charge which is a function of the target thickness is given and compared with the exact numerical value. The results agree to better than 5% over a wide range of target composition and thickness. (orig.)
Theory of Multiple Coulomb Scattering from Extended Nuclei
Cooper, L. N.; Rainwater, J.
1954-08-01
Two independent methods are described for calculating the multiple scattering distribution for projected angle scattering resulting when very high energy charged particles traverse a thick scatterer. The results are compared with the theories of Moliere and Olbert.
Lateral displacement in small angle multiple scattering
Energy Technology Data Exchange (ETDEWEB)
Bichsel, H.; Hanson, K.M.; Schillaci, K.M. (Los Alamos National Lab., NM (USA))
1982-07-01
Values have been calculated for the average lateral displacement in small angle multiple scattering of protons with energies of several hundred MeV. The calculations incorporate the Moliere distribution which does not make the gaussian approximations of the distribution in projected angle and lateral deflections. Compared to other published data, such approximations can lead to errors in the lateral displacement of up to 10% in water.
Multiple Scattering Model for Optical Coherence Tomography with Rytov Approximation
Li, Muxingzi
2017-01-01
of speckles due to multiple scatterers within the coherence length, and other random noise. Motivated by the above two challenges, a multiple scattering model based on Rytov approximation and Gaussian beam optics is proposed for the OCT setup. Some previous
International Nuclear Information System (INIS)
Jayaswal, B.; Mazumder, S.
1998-09-01
Small-angle scattering data from strong scattering systems, e.g. porous materials, cannot be analysed invoking single scattering approximation as specimen needed to replicate the bulk matrix in essential properties are too thick to validate the approximation. The presence of multiple scattering is indicated by invalidity of the functional invariance property of the observed scattering profile with variation of sample thickness and/or wave length of the probing radiation. This article delineates how non accounting of multiple scattering affects the results of analysis and then how to correct the data for its effect. It deals with an algorithm to extract single scattering profile from small-angle scattering data affected by multiple scattering. The algorithm can process the scattering data and deduce single scattering profile in absolute scale. A software package, SIMSAS, is introduced for executing this inversion step. This package is useful both to simulate and to analyse multiple small-angle scattering data. (author)
Multiple scattering theory for space filling potentials
International Nuclear Information System (INIS)
Butler, W.H.; Brown, R.G.; Nesbet, R.K.
1990-01-01
Multiple scattering theory (MST) provides an efficient technique for solving the wave equation for the special case of muffin-tin potentials. Here MST is extended to treat space filling non-muffin tin potentials and its validity, accuracy and efficiency are tested by application of the two dimensional empty lattice test. For this test it is found that the traditional formulation of MST does not coverage as the number of partial waves is increased. A simple modification of MST, however, allows this problem to be solved exactly and efficiently. 15 refs., 3 tabs
Quantum optics in multiple scattering random media
DEFF Research Database (Denmark)
Lodahl, Peter; Lagendijk, Ad
2005-01-01
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......-tions that should be readily attainable experimentally is devised. Figure 1. Inverse total transmission of shot noise (left) and technical noise (right) as a function of the thickness of the ran-dom medium. The experimental data are well explained by theory (curves). [1] J. Tworzydlo and C.W.J. Beenakker, Phys. Rev...
Coulomb interaction in multiple scattering theory
International Nuclear Information System (INIS)
Ray, L.; Hoffmann, G.W.; Thaler, R.M.
1980-01-01
The treatment of the Coulomb interaction in the multiple scattering theories of Kerman-McManus-Thaler and Watson is examined in detail. By neglecting virtual Coulomb excitations, the lowest order Coulomb term in the Watson optical potential is shown to be a convolution of the point Coulomb interaction with the distributed nuclear charge, while the equivalent Kerman-McManus-Thaler Coulomb potential is obtained from an averaged, single-particle Coulombic T matrix. The Kerman-McManus-Thaler Coulomb potential is expressed as the Watson Coulomb term plus additional Coulomb-nuclear and Coulomb-Coulomb cross terms, and the omission of the extra terms in usual Kerman-McManus-Thaler applications leads to negative infinite total reaction cross section predictions and incorrect pure Coulomb scattering limits. Approximations are presented which eliminate these anomalies. Using the two-potential formula, the full projectile-nucleus T matrix is separated into two terms, one resulting from the distributed nuclear charge and the other being a Coulomb distorted nuclear T matrix. It is shown that the error resulting from the omission of the Kerman-McManus-Thaler Coulomb terms is effectively removed when the pure Coulomb T matrix in Kerman-McManus-Thaler is replaced by the analogous quantity in the Watson approach. Using the various approximations, theoretical angular distributions are obtained for 800 MeV p+ 208 Pb elastic scattering and compared with experimental data
Multiple-scattering in radar systems: A review
International Nuclear Information System (INIS)
Battaglia, Alessandro; Tanelli, Simone; Kobayashi, Satoru; Zrnic, Dusan; Hogan, Robin J.; Simmer, Clemens
2010-01-01
Although extensively studied within the lidar community, the multiple scattering phenomenon has always been considered a rare curiosity by radar meteorologists. Up to few years ago its appearance has only been associated with two- or three-body-scattering features (e.g. hail flares and mirror images) involving highly reflective surfaces. Recent atmospheric research aimed at better understanding of the water cycle and the role played by clouds and precipitation in affecting the Earth's climate has driven the deployment of high frequency radars in space. Examples are the TRMM 13.5 GHz, the CloudSat 94 GHz, the upcoming EarthCARE 94 GHz, and the GPM dual 13-35 GHz radars. These systems are able to detect the vertical distribution of hydrometeors and thus provide crucial feedbacks for radiation and climate studies. The shift towards higher frequencies increases the sensitivity to hydrometeors, improves the spatial resolution and reduces the size and weight of the radar systems. On the other hand, higher frequency radars are affected by stronger extinction, especially in the presence of large precipitating particles (e.g. raindrops or hail particles), which may eventually drive the signal below the minimum detection threshold. In such circumstances the interpretation of the radar equation via the single scattering approximation may be problematic. Errors will be large when the radiation emitted from the radar after interacting more than once with the medium still contributes substantially to the received power. This is the case if the transport mean-free-path becomes comparable with the instrument footprint (determined by the antenna beam-width and the platform altitude). This situation resembles to what has already been experienced in lidar observations, but with a predominance of wide- versus small-angle scattering events. At millimeter wavelengths, hydrometeors diffuse radiation rather isotropically compared to the visible or near infrared region where scattering is
Static and dynamic properties of multiple light scattering
Štěpánek, Petr
1993-11-01
We have examined the onset and evolution of multiple scattering of light on a series of latex dispersions as a function of increasing volume concentration φ of particles. We have shown that using vertically polarized incident light, the static scattered intensity becomes progressively depolarized, with increasing φ. The polarization of scattered light is completely random in the limit of strong multiple scattering. The spectra of decay times of dynamic light scattering display a region of oligo scattering at intermediate φ where both the single and multiple scattering components can be dynamically identified. For φ≳0.03 the limit of diffusive transport of light is attained. The obtained results confirm that our earlier measurements of dynamic light scattering on systems exhibiting critical opalescence are not influenced by multiple light scattering.
Multiple scattering effects in 7Li
International Nuclear Information System (INIS)
Cox, A.J.; Warner, P.C.
1985-01-01
The differential cross-sections for the production of 0.478 MeV γ-rays following the inelastic scattering of 14 MeV neutrons in large samples of LiF, which will be used in fusion reactor blankets, have been measured. The neutrons were produced using the 3 H(d,n) 4 α reaction, with the deuterons being accelerated by a 150 kV SAMES type accelerator. In order to reduce the background level the γ-ray signal was gated, using a time of flight technique based on the α-particle associated with neutron production. Measurements of the γ-ray production differential cross-sections were made for various thicknesses of LiF. The results were compared to the predictions of the Monte Carlo Computer Code, MORSE, with an agreement of +-11% being achieved. In addition a phenomenological expression was found which is capable of predicting the variation in cross-sections with thickness due to multiple scattering effects to within +-12%. (author)
Multiple small-angle neutron scattering studies of anisotropic materials
Allen, A J; Long, G G; Ilavsky, J
2002-01-01
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.)
Convergence of the multiple scattering expansion in XAFS and XANES
International Nuclear Information System (INIS)
Rehr, J.J.
1992-01-01
The convergence of the multiple-scattering expansion of XAFS and XANES by explicit path-bypath calculations. The approach is based on the fast scattering matrix formalism of Rehr and Albers, together with an automated path finder and filters that exclude negligible paths. High-order scattering terms are found to be essential, especially at low energies. Several factors including the magnitude of curved wave scattering amplitudes, inelastic losses and multiple-scattering Debye-Waller factors control convergence of the expansion. The convergence is illustrated explicitly for the case of diatomic molecules
Numerical modelling of multiple scattering between two elastical particles
DEFF Research Database (Denmark)
Bjørnø, Irina; Jensen, Leif Bjørnø
1998-01-01
in suspension have been studied extensively since Foldy's formulation of his theory for isotropic scattering by randomly distributed scatterers. However, a number of important problems related to multiple scattering are still far from finding their solutions. A particular, but still unsolved, problem......Multiple acoustical signal interactions with sediment particles in the vicinity of the seabed may significantly change the course of sediment concentration profiles determined by inversion from acoustical backscattering measurements. The scattering properties of high concentrations of sediments...... is the question of proximity thresholds for influence of multiple scattering in terms of particle properties like volume fraction, average distance between particles or other related parameters. A few available experimental data indicate a significance of multiple scattering in suspensions where the concentration...
Compton-scatter tissue densitometry: calculation of single and multiple scatter photon fluences
International Nuclear Information System (INIS)
Battista, J.J.; Bronskill, M.J.
1978-01-01
The accurate measurement of in vivo electron densities by the Compton-scatter method is limited by attenuations and multiple scattering in the patient. Using analytic and Monte Carlo calculation methods, the Clarke tissue density scanner has been modelled for incident monoenergetic photon energies from 300 to 2000 keV and for mean scattering angles of 30 to 130 degrees. For a single detector focussed to a central position in a uniform water phantom (25 x 25 x 25 cm 3 ) it has been demonstrated that: (1) Multiple scatter contamination is an inherent limitation of the Compton-scatter method of densitometry which can be minimised, but not eliminated, by improving the energy resolution of the scattered radiation detector. (2) The choice of the incident photon energy is a compromise between the permissible radiation dose to the patient and the tolerable level of multiple scatter contamination. For a mean scattering angle of 40 degrees, the intrinsic multiple-single scatter ratio decreases from 64 to 35%, and the radiation dose (per measurement) increases from 1.0 to 4.1 rad, as the incident photon energy increases from 300 to 2000 keV. These doses apply to a sampled volume of approximately 0.3 cm 3 and an electron density precision of 0.5%. (3) The forward scatter densitometer configuration is optimum, minimising both the dose and the multiple scatter contamination. For an incident photon energy of 1250 keV, the intrinsic multiple-single scatter ratio reduces from 122 to 27%, and the dose reduces from 14.3 to 1.2 rad, as the mean scattering angle decreases from 130 to 30 degrees. These calculations have been confirmed by experimental measurements. (author)
Acoustic scattering by multiple elliptical cylinders using collocation multipole method
International Nuclear Information System (INIS)
Lee, Wei-Ming
2012-01-01
This paper presents the collocation multipole method for the acoustic scattering induced by multiple elliptical cylinders subjected to an incident plane sound wave. To satisfy the Helmholtz equation in the elliptical coordinate system, the scattered acoustic field is formulated in terms of angular and radial Mathieu functions which also satisfy the radiation condition at infinity. The sound-soft or sound-hard boundary condition is satisfied by uniformly collocating points on the boundaries. For the sound-hard or Neumann conditions, the normal derivative of the acoustic pressure is determined by using the appropriate directional derivative without requiring the addition theorem of Mathieu functions. By truncating the multipole expansion, a finite linear algebraic system is derived and the scattered field can then be determined according to the given incident acoustic wave. Once the total field is calculated as the sum of the incident field and the scattered field, the near field acoustic pressure along the scatterers and the far field scattering pattern can be determined. For the acoustic scattering of one elliptical cylinder, the proposed results match well with the analytical solutions. The proposed scattered fields induced by two and three elliptical–cylindrical scatterers are critically compared with those provided by the boundary element method to validate the present method. Finally, the effects of the convexity of an elliptical scatterer, the separation between scatterers and the incident wave number and angle on the acoustic scattering are investigated.
Diffractive scattering on nuclei in multiple scattering theory with inelastic screening
International Nuclear Information System (INIS)
Zoller, V.R.
1988-01-01
The cross sections for the diffractive scattering of hadrons on nuclei are calculated in the two-channel approximation of multiple scattering theory. In contrast to the standard Glauber approach, it is not assumed that the nucleon scattering profile is a Gaussian or that the Regge radius of the hadron is small compared to the nuclear radius. The AGK Reggeon diagrammatic technique is used to calculate the topological cross sections and the cross sections for coherent and incoherent diffractive dissociation and quasielastic scattering. The features of hadron-nucleus scattering at superhigh energies are discussed
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
1997-12-31
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.
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
1996-12-31
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.
Reproducibility of artificial multiple scattering media
Marakis, Evangelos; van Harten, Wouter; Uppu, Ravitej; Pinkse, Pepijn Willemszoon Harry
2016-01-01
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
Certain theories of multiple scattering in random media of discrete scatterers
International Nuclear Information System (INIS)
Olsen, R.L.; Kharadly, M.M.Z.; Corr, D.G.
1976-01-01
New information is presented on the accuracy of the heuristic approximations in two important theories of multiple scattering in random media of discrete scatterers: Twersky's ''free-space'' and ''two-space scatterer'' formalisms. Two complementary approaches, based primarily on a one-dimensional model and the one-dimensional forms of the theories, are used. For scatterer distributions of low average density, the ''heuristic'' asymptotic forms for the coherent field and the incoherent intensity are compared with asymptotic forms derived from a systematic analysis of the multiple scattering processes. For distributions of higher density, both in the average number of scatterers per wavelength and in the degree of packing of finite-size scatterers, the analysis is carried out ''experimentally'' by means of a Monte Carlo computer simulation. Approximate series expressions based on the systematic approach are numerically evaluated along with the heuristic expressions. The comparison (for both forward- and back-scattered field moments) is made for the worst-case conditions of strong multiple scattering for which the theories have not previously been evaluated. Several significant conclusions are drawn which have certain practical implications: in application of the theories to describe some of the scattering phenomena which occur in the troposphere, and in the further evaluation of the theories using experiments on physical models
Assessment of Multiple Scattering Errors of Laser Diffraction Instruments
National Research Council Canada - National Science Library
Strakey, Peter
2003-01-01
The accuracy of two commercial laser diffraction instruments was compared under conditions of multiple scattering designed to simulate the high droplet number densities encountered in liquid propellant rocket combustors...
Multiple scattering approach to X-ray absorption spectroscopy
International Nuclear Information System (INIS)
Benfatto, M.; Wu Ziyu
2003-01-01
In this paper authors present the state of the art of the theoretical background needed for analyzing X-ray absorption spectra in the whole energy range. The multiple-scattering (MS) theory is presented in detail with some applications on real systems. Authors also describe recent progress in performing geometrical fitting of the XANES (X-ray absorption near-edge structure) energy region and beyond using a full multiple-scattering approach
Effects of multiple scattering and atmospheric aerosol on the polarization of the twilight sky
International Nuclear Information System (INIS)
Ugolnikov, Oleg S.; Postylyakov, Oleg V.; Maslov, Igor A.
2004-01-01
The paper presents a review of a number of wide-angle polarization CCD-measurements of the twilight sky in V and R color bands with effective wavelengths 550 and 700nm. The basic factors affecting (usually decreasing) the polarization of the twilight sky are the atmospheric aerosol scattering and multiple scattering. These effects were distinguished from each other, and a method of multiple-scattering separation is discussed. The results are compared with the data of numerical simulation of radiative transfer in the atmosphere for different aerosol models. The whole twilight period is divided into different stages with different mechanisms forming the twilight-sky polarization properties
SWIMS: a small-angle multiple scattering computer code
International Nuclear Information System (INIS)
Sayer, R.O.
1976-07-01
SWIMS (Sigmund and WInterbon Multiple Scattering) is a computer code for calculation of the angular dispersion of ion beams that undergo small-angle, incoherent multiple scattering by gaseous or solid media. The code uses the tabulated angular distributions of Sigmund and Winterbon for a Thomas-Fermi screened Coulomb potential. The fraction of the incident beam scattered into a cone defined by the polar angle α is computed as a function of α for reduced thicknesses over the range 0.01 less than or equal to tau less than or equal to 10.0. 1 figure, 2 tables
Significance of multiple scattering in imaging through turbid media
International Nuclear Information System (INIS)
Zardecki, A.; Gerstl, S.A.W.
1986-01-01
The degradation of image quality in a turbid medium is analyzed within the framework of the small-angle approximation, the diffusion approximation, and a rigorous two-dimensional radiative transfer equation. These three approaches allow us to emphasize different aspects of the imaging problem when multiple scattering effects are important. For a medium with a forward-peaked phase function, the separation of multiple scattering into a series of scatterings of various order provides a fruitful technique. The use of the diffusion approximation and transport theory extends the determination of the modulation transfer function to a turbid medium with an arbitrary degree of anisotropy
Method for measuring multiple scattering corrections between liquid scintillators
Energy Technology Data Exchange (ETDEWEB)
Verbeke, J.M., E-mail: verbeke2@llnl.gov; Glenn, A.M., E-mail: glenn22@llnl.gov; Keefer, G.J., E-mail: keefer1@llnl.gov; Wurtz, R.E., E-mail: wurtz1@llnl.gov
2016-07-21
A time-of-flight method is proposed to experimentally quantify the fractions of neutrons scattering between scintillators. An array of scintillators is characterized in terms of crosstalk with this method by measuring a californium source, for different neutron energy thresholds. The spectral information recorded by the scintillators can be used to estimate the fractions of neutrons multiple scattering. With the help of a correction to Feynman's point model theory to account for multiple scattering, these fractions can in turn improve the mass reconstruction of fissile materials under investigation.
Electron Raman scattering in asymmetrical multiple quantum wells
International Nuclear Information System (INIS)
Betancourt-Riera, R; Rosas, R; Marin-Enriquez, I; Riera, R; Marin, J L
2005-01-01
Optical properties of asymmetrical multiple quantum wells for the construction of quantum cascade lasers are calculated, and expressions for the electronic states of asymmetrical multiple quantum wells are presented. The gain and differential cross-section for an electron Raman scattering process are obtained. Also, the emission spectra for several scattering configurations are discussed, and the corresponding selection rules for the processes involved are studied; an interpretation of the singularities found in the spectra is given. The electron Raman scattering studied here can be used to provide direct information about the efficiency of the lasers
Markov chain solution of photon multiple scattering through turbid slabs.
Lin, Ying; Northrop, William F; Li, Xuesong
2016-11-14
This work introduces a Markov Chain solution to model photon multiple scattering through turbid slabs via anisotropic scattering process, i.e., Mie scattering. Results show that the proposed Markov Chain model agree with commonly used Monte Carlo simulation for various mediums such as medium with non-uniform phase functions and absorbing medium. The proposed Markov Chain solution method successfully converts the complex multiple scattering problem with practical phase functions into a matrix form and solves transmitted/reflected photon angular distributions by matrix multiplications. Such characteristics would potentially allow practical inversions by matrix manipulation or stochastic algorithms where widely applied stochastic methods such as Monte Carlo simulations usually fail, and thus enable practical diagnostics reconstructions such as medical diagnosis, spray analysis, and atmosphere sciences.
Multiple scattering effects in depth resolution of elastic recoil detection
International Nuclear Information System (INIS)
Wielunski, L.S.; Harding, G.L.
1998-01-01
Elastic Recoil Detection (ERD) is used to profile hydrogen and other low mass elements in thin films at surface and interfaces in a similar way that Rutherford Backscattering Spectroscopy (RBS) is used to detect and profile heavy elements. It is often assumed that the depth resolutions of these two techniques are similar. However, in contrast to typical RBS, the depth resolution of ERD is limited substantially by multiple scattering. In experimental data analysis and/or spectra simulations of a typical RBS measurement multiple scattering effects are often ignored. Computer programs used in IBA, such as RUMP, HYPRA or RBX do not include multiple scattering effects at all. In this paper, using practical thin metal structures with films containing intentionally introduced hydrogen, we demonstrate experimental ERD depth resolution and sensitivity limitations. The effects of sample material and scattering angle are also discussed. (authors)
Multiple scattering effects in depth resolution of elastic recoil detection
Energy Technology Data Exchange (ETDEWEB)
Wielunski, L.S.; Harding, G.L. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Telecommunications and Industrial Physics; Szilagyi, E. [KFKI Research Institute for Particle and Nuclear Physics, Budapest, (Hungary)
1998-06-01
Elastic Recoil Detection (ERD) is used to profile hydrogen and other low mass elements in thin films at surface and interfaces in a similar way that Rutherford Backscattering Spectroscopy (RBS) is used to detect and profile heavy elements. It is often assumed that the depth resolutions of these two techniques are similar. However, in contrast to typical RBS, the depth resolution of ERD is limited substantially by multiple scattering. In experimental data analysis and/or spectra simulations of a typical RBS measurement multiple scattering effects are often ignored. Computer programs used in IBA, such as RUMP, HYPRA or RBX do not include multiple scattering effects at all. In this paper, using practical thin metal structures with films containing intentionally introduced hydrogen, we demonstrate experimental ERD depth resolution and sensitivity limitations. The effects of sample material and scattering angle are also discussed. (authors). 19 refs., 4 figs.
Multiple scattering theory for superconducting heterostructures
Energy Technology Data Exchange (ETDEWEB)
Ujfalussy, Balazs [Wigner Research Centre for Physics, Budapest (Hungary)
2016-07-01
We generalize the screened Korringa-Kohn-Rostoker method for solving the corresponding Kohn-Sham-Bogoliubov-de Gennes equations for surfaces and interfaces. As an application of the theory, we study the quasiparticle spectrum of Au overlayers on a Nb(100) host. We find that within the superconducting gap region, the quasiparticle spectrum consists of Andreev bound states with a dispersion which is closely connected to the underlying electronic structure of the overlayer. We also find that the spectrum has a strongly k-dependent induced gap. The properties of the gap are discussed in relation to the thickness of the overlayer, and it is shown that certain states do not participate in the Andreev scattering process. From the thickness dependence of the gap size we calculate the superconducting critical temperature of Au/Nb(100) heterostructures what we compare with with experiments. Moreover, predictions are made for similar heterostructures of other compounds.
Correlation expansion: a powerful alternative multiple scattering calculation method
International Nuclear Information System (INIS)
Zhao Haifeng; Wu Ziyu; Sebilleau, Didier
2008-01-01
We introduce a powerful alternative expansion method to perform multiple scattering calculations. In contrast to standard MS series expansion, where the scattering contributions are grouped in terms of scattering order and may diverge in the low energy region, this expansion, called correlation expansion, partitions the scattering process into contributions from different small atom groups and converges at all energies. It converges faster than MS series expansion when the latter is convergent. Furthermore, it takes less memory than the full MS method so it can be used in the near edge region without any divergence problem, even for large clusters. The correlation expansion framework we derive here is very general and can serve to calculate all the elements of the scattering path operator matrix. Photoelectron diffraction calculations in a cluster containing 23 atoms are presented to test the method and compare it to full MS and standard MS series expansion
Multiple scattering theory of radiative transfer in inhomogeneous atmospheres.
Kanal, M.
1973-01-01
In this paper we treat the multiple scattering theory of radiative transfer in plane-parallel inhomogeneous atmospheres. The treatment presented here may be adopted to model atmospheres characterized by an optical depth dependent coherent scattering phase function. For the purpose of illustration we consider the semi-infinite medium in which the absorption property of the atmosphere is characterized by an exponential function. The methodology employed here is the extension of the case treated previously by the author for homogeneous atmospheres.
Simulation of multiple scattering background in heavy ion backscattering spectrometry
International Nuclear Information System (INIS)
Li, M.M.; O'Connor, D.J.
1999-01-01
With the development of heavy ion backscattering spectrometry (HIBS) for the detection of trace quantities of heavy-atom impurities on Si surfaces, it is necessary to quantify the multiple scattering contribution to the spectral background. In the present work, the Monte Carlo computer simulation program TRIM has been used to study the backscattering spectrum and the multiple scattering background features for heavy ions C, Ne, Si, Ar and Kr impinging on four types of targets: (1) a single ultra-thin (free standing) Au film of 10 A thickness, (2) a 10 A Au film on a 50 A Si surface, (3) a 10 A Au film on an Si substrate (10 000 A), and (4) a thick target (10 000 A) of pure Si. The ratio of the signal from the Au thin layer to the background due to multiple scattering has been derived by fitting the simulation results. From the simulation results, it is found that the Au film contributes to the background which the Si plays a role in developing due to the ion's multiple scattering in the substrate. Such a background is generated neither by only the Au thin layer nor by the pure Si substrate independently. The corresponding mechanism of multiple scattering in the target can be explained as one large-angle scattering in the Au layer and subsequently several small angle scatterings in the substrate. This study allows an appropriate choice of incident beam species and energy range when the HIBS is utilized to analyse low level impurities in Si wafers
Flesia, C.; Schwendimann, P.
1992-01-01
The contribution of the multiple scattering to the lidar signal is dependent on the optical depth tau. Therefore, the radar analysis, based on the assumption that the multiple scattering can be neglected is limited to cases characterized by low values of the optical depth (tau less than or equal to 0.1) and hence it exclude scattering from most clouds. Moreover, all inversion methods relating lidar signal to number densities and particle size must be modified since the multiple scattering affects the direct analysis. The essential requests of a realistic model for lidar measurements which include the multiple scattering and which can be applied to practical situations follow. (1) Requested are not only a correction term or a rough approximation describing results of a certain experiment, but a general theory of multiple scattering tying together the relevant physical parameter we seek to measure. (2) An analytical generalization of the lidar equation which can be applied in the case of a realistic aerosol is requested. A pure analytical formulation is important in order to avoid the convergency and stability problems which, in the case of numerical approach, are due to the large number of events that have to be taken into account in the presence of large depth and/or a strong experimental noise.
Monte Carlo simulations of multiple scattering effects in ERD measurements
International Nuclear Information System (INIS)
Doyle, Barney Lee; Arstila, Kai.; Nordlumd, K.; Knapp, James Arthur
2003-01-01
Multiple scattering effects in ERD measurements are studied by comparing two Monte Carlo simulation codes, representing different approaches to obtain acceptable statistics, to experimental spectra measured from a HfO 2 sample with a time-of-flight-ERD setup. The results show that both codes can reproduce the absolute detection yields and the energy distributions in an adequate way. The effect of the choice of the interatomic potential in multiple scattering effects is also studied. Finally the capabilities of the MC simulations in the design of new measurement setups are demonstrated by simulating the recoil energy spectra from a WC x N y sample with a low energy heavy ion beam.
Effects of multiple scattering and target structure on photon emission
International Nuclear Information System (INIS)
Blankenbecler, R.
1996-05-01
The Landau-Pomeranchuk-Migdal effect is the suppression of Bethe-Heitler radiation caused by multiple scattering in the target medium. The quantum treatment given by S.D. Drell and the author for homogeneous targets of finite thickness will be reviewed. It will then be extended to structured targets. In brief, it is shown that radiators composed of separated plates or of a medium with a spatially varying radiation length can exhibit unexpected structure, even coherence maxima and minima, in their photon spectra. Finally, a functional integral method for performing the averaging implicit in multiple scattering will be briefly discussed and the leading corrections to previous results evaluated
Collective hypersonic excitations in strongly multiple scattering colloids.
Still, T; Gantzounis, G; Kiefer, D; Hellmann, G; Sainidou, R; Fytas, G; Stefanou, N
2011-04-29
Unprecedented low-dispersion high-frequency acoustic excitations are observed in dense suspensions of elastically hard colloids. The experimental phononic band structure for SiO(2) particles with different sizes and volume fractions is well represented by rigorous full-elastodynamic multiple-scattering calculations. The slow phonons, which do not relate to particle resonances, are localized in the surrounding liquid medium and stem from coherent multiple scattering that becomes strong in the close-packing regime. Such rich phonon-matter interactions in nanostructures, being still unexplored, can open new opportunities in phononics.
Multiple scattering theory of X-ray absorption. A review
International Nuclear Information System (INIS)
Fonda, L.
1991-11-01
We review the basic elements of the theory of X-ray absorption using the tools provided by the theory of multiple scattering. A momentum space approach of clear physical insight is used where the final formulas expressing EXAFS and XANES, i.e. the structures appearing in the absorption coefficient above the edge of a deep core level threshold, are given in terms of eigenstates of the photoelectron momentum. A simple graphic representation is given for the multiple scattering function. (author). 38 refs, 4 figs, 1 tab
Multiple scattering problems in heavy ion elastic recoil detection analysis
International Nuclear Information System (INIS)
Johnston, P.N.; El Bouanani, M.; Stannard, W.B.; Bubb, I.F.; Cohen, D.D.; Dytlewski, N.; Siegele, R.
1998-01-01
A number of groups use Heavy Ion Elastic Recoil Detection Analysis (HIERDA) to study materials science problems. Nevertheless, there is no standard methodology for the analysis of HIERDA spectra. To overcome this deficiency we have been establishing codes for 2-dimensional data analysis. A major problem involves the effects of multiple and plural scattering which are very significant, even for quite thin (∼100 nm) layers of the very heavy elements. To examine the effects of multiple scattering we have made comparisons between the small-angle model of Sigmund et al. and TRIM calculations. (authors)
Elastic scattering of protons at the nucleus 6He in the Glauber multiple scattering theory
International Nuclear Information System (INIS)
Prmantayeva, B.A.; Temerbayev, A.A.; Tleulessova, I.K.; Ibrayeva, E.T.
2011-01-01
Calculation is submitted for the differential cross sections of elastic p 6 He-scattering at energies of 70 and 700 MeV/nucleon within the framework of the Glauber theory of multiple diffraction scattering. We used the three-particle wave functions: α-n-n with realistic intercluster potentials. The sensitivity of elastic scattering to the proton-nuclear interaction and the structure of nuclei had been investigated. It is shown that the contribution of small components of the wave function as well as the multiplicity of the scattering operator Ω should be considered to describe a cross-section in broad angular range . A comparison with available experimental data was made. (author)
An empirical correction for moderate multiple scattering in super-heterodyne light scattering.
Botin, Denis; Mapa, Ludmila Marotta; Schweinfurth, Holger; Sieber, Bastian; Wittenberg, Christopher; Palberg, Thomas
2017-05-28
Frequency domain super-heterodyne laser light scattering is utilized in a low angle integral measurement configuration to determine flow and diffusion in charged sphere suspensions showing moderate to strong multiple scattering. We introduce an empirical correction to subtract the multiple scattering background and isolate the singly scattered light. We demonstrate the excellent feasibility of this simple approach for turbid suspensions of transmittance T ≥ 0.4. We study the particle concentration dependence of the electro-kinetic mobility in low salt aqueous suspension over an extended concentration regime and observe a maximum at intermediate concentrations. We further use our scheme for measurements of the self-diffusion coefficients in the fluid samples in the absence or presence of shear, as well as in polycrystalline samples during crystallization and coarsening. We discuss the scope and limits of our approach as well as possible future applications.
Multiple scattering and attenuation corrections in Deep Inelastic Neutron Scattering experiments
International Nuclear Information System (INIS)
Dawidowski, J; Blostein, J J; Granada, J R
2006-01-01
Multiple scattering and attenuation corrections in Deep Inelastic Neutron Scattering experiments are analyzed. The theoretical basis of the method is stated, and a Monte Carlo procedure to perform the calculation is presented. The results are compared with experimental data. The importance of the accuracy in the description of the experimental parameters is tested, and the implications of the present results on the data analysis procedures is examined
Imaging moving objects from multiply scattered waves and multiple sensors
International Nuclear Information System (INIS)
Miranda, Analee; Cheney, Margaret
2013-01-01
In this paper, we develop a linearized imaging theory that combines the spatial, temporal and spectral components of multiply scattered waves as they scatter from moving objects. In particular, we consider the case of multiple fixed sensors transmitting and receiving information from multiply scattered waves. We use a priori information about the multipath background. We use a simple model for multiple scattering, namely scattering from a fixed, perfectly reflecting (mirror) plane. We base our image reconstruction and velocity estimation technique on a modification of a filtered backprojection method that produces a phase-space image. We plot examples of point-spread functions for different geometries and waveforms, and from these plots, we estimate the resolution in space and velocity. Through this analysis, we are able to identify how the imaging system depends on parameters such as bandwidth and number of sensors. We ultimately show that enhanced phase-space resolution for a distribution of moving and stationary targets in a multipath environment may be achieved using multiple sensors. (paper)
High-energy expansion for nuclear multiple scattering
International Nuclear Information System (INIS)
Wallace, S.J.
1975-01-01
The Watson multiple scattering series is expanded to develop the Glauber approximation plus systematic corrections arising from three (1) deviations from eikonal propagation between scatterings, (2) Fermi motion of struck nucleons, and (3) the kinematic transformation which relates the many-body scattering operators of the Watson series to the physical two-body scattering amplitude. Operators which express effects ignored at the outset to obtain the Glauber approximation are subsequently reintroduced via perturbation expansions. Hence a particular set of approximations is developed which renders the sum of the Watson series to the Glauber form in the center of mass system, and an expansion is carried out to find leading order corrections to that summation. Although their physical origins are quite distinct, the eikonal, Fermi motion, and kinematic corrections produce strikingly similar contributions to the scattering amplitude. It is shown that there is substantial cancellation between their effects and hence the Glauber approximation is more accurate than the individual approximations used in its derivation. It is shown that the leading corrections produce effects of order (2kR/subc/) -1 relative to the double scattering term in the uncorrected Glauber amplitude, hk being momentum and R/subc/ the nuclear char []e radius. The leading order corrections are found to be small enough to validate quatitative analyses of experimental data for many intermediate to high energy cases and for scattering angles not limited to the very forward region. In a Gaussian model, the leading corrections to the Glauber amplitude are given as convenient analytic expressions
Multiple scattering in the nuclear rearrangement reactions at medium energy
International Nuclear Information System (INIS)
Tekou, A.
1980-09-01
It is shown that the multiple scattering mechanism is very important in the transfer of the large momenta involved in the nuclear rearrangement reactions at medium energy. In contrast to the usual belief, the reaction cross-section is not very sensitive to the high momenta components of the nuclear wave function. The multiple scattering mechanism is especially important in 4 He(p,d) 3 He reaction around 800 MeV. Here the collisions involving two nucleons of the target nucleus are dominant. The triple collisions contribution is also important. The four collision contribution is negligible in the forward direction and sizeable at large angles. Thus, using the K.M.T. approach in DWBA calculations, the second order term of the optical potential must be included. So, is it not well established that the second term of the K.M.T. optical potential is important for the proton elastic scattering on light nuclei. (author)
Multiple scattering in synchrotron studies of disordered materials
International Nuclear Information System (INIS)
Poulsen, H.F.; Neuefeind, J.
1995-01-01
A formalism for the multiple scattering and self-absorption in synchrotron studies of disordered materials is presented. The formalism goes beyond conventionally used approximations and treat the cross sections, the beam characteristics, the state of polarization, and the electronic correction terms in full. Using hard X-rays it is shown how the simulated distributions can be directly compared to experimental data. ((orig.))
Effects of multiple scattering on radiative properties of soot fractal aggregates
International Nuclear Information System (INIS)
Yon, Jérôme; Liu, Fengshan; Bescond, Alexandre; Caumont-Prim, Chloé; Rozé, Claude; Ouf, François-Xavier; Coppalle, Alexis
2014-01-01
The in situ optical characterization of smokes composed of soot particles relies on light extinction, angular static light scattering (SLS), or laser induced incandescence (LII). These measurements are usually interpreted by using the Rayleigh–Debye–Gans theory for Fractal Aggregates (RDG-FA). RDG-FA is simple to use but it completely neglects the impact of multiple scattering (MS) within soot aggregates. In this paper, based on a scaling approach that takes into account MS effects, an extended form of the RDG-FA theory is proposed in order to take into account these effects. The parameters of this extended theory and their dependency on the number of primary sphere inside the aggregate (1 p <1006) and on the wavelength (266nm<λ<1064nm) are evaluated thanks to rigorous calculations based on discrete dipole approximation (DDA) and generalized multi-sphere Mie-solution (GMM) calculations. This study shows that size determination by SLS is not distorted by MS effect. On the contrary, it is shown that fractal dimension can be misinterpreted by light scattering experiments, especially at short wavelengths. MS effects should be taken into account for the interpretation of absorption measurements that are involved in LII or extinction measurements. -- Highlights: • We incorporate multiple scattering effects in a scaling approach for fractal aggregates. • A generalized structure factor is introduced for implementation in RDG-FA theory. • Forward scattering is affected by multiple scattering as well as power law regime. • Absorption cross sections are affected by multiple scattering. • Absorption cross sections are 11% higher than that for forward scattering
Resonant Rayleigh scattering of exciton-polaritons in multiple quantum wells
DEFF Research Database (Denmark)
Malpuech, Guillaume; Kavokin, Alexey; Langbein, Wolfgang Werner
2000-01-01
A theoretical concept of resonant Rayleigh scattering (RRS) of exciton-polaritons in multiple quantum wells (QWs) is presented. The optical coupling between excitons in different QWs can strongly affect the RRS dynamics, giving rise to characteristic temporal oscillations on a picosecond scale....... Bragg and anti-Bragg arranged QW structures with the same excitonic parameters are predicted to have drastically different RRS spectra. Experimental data on the RRS from multiple QWs show the predicted strong temporal oscillations at small scattering angles, which are well explained by the presented...
Continuum multiple-scattering approach to electron-molecule scattering and molecular photoionization
International Nuclear Information System (INIS)
Dehmer, J.L.; Dill, D.
1979-01-01
The multiple-scattering approach to the electronic continuum of molecules is described. The continuum multiple-scattering model (CMSM) was developed as a survey tool and, as such was required to satisfy two requirements. First, it had to have a very broad scope, which means (i) molecules of arbitrary geometry and complexity containing any atom in the periodic system, (ii) continuum electron energies from 0-1000 eV, and (iii) capability to treat a large range of processes involving both photoionization and electron scattering. Second, the structure of the theory was required to lend itself to transparent, physical interpretation of major spectral features such as shape resonances. A comprehensive theoretical framework for the continuum multiple scattering method is presented, as well as its applications to electron-molecule scattering and molecular photoionization. Highlights of recent applications in these two areas are reviewed. The major impact of the resulting studies over the last few years has been to establish the importance of shape resonances in electron collisions and photoionization of practically all (non-hydride) molecules
Renormalized multiple-scattering theory of photoelectron diffraction
International Nuclear Information System (INIS)
Biagini, M.
1993-01-01
The current multiple-scattering cluster techniques for the calculation of x-ray photoelectron and Auger-electron diffraction patterns consume much computer time in the intermediate-energy range (200--1000 eV); in fact, because of the large value of the electron mean free path and of the large forward-scattering amplitude at such energies, the electron samples a relatively large portion of the crystal, so that the number of paths to be considered becomes dramatically high. An alternative method is developed in the present paper: instead of calculating the individual contribution from each single path, the scattering matrix of each plane parallel to the surface is calculated with a renormalization process that calculates every scattering event in the plane up to infinite order. Similarly the scattering between two planes is calculated up to infinite order, and the double-plane scattering matrix is introduced. The process may then be applied to the calculation of a larger set of atomic layers. The advantage of the method is that a relatively small number of internuclear vectors have been used to obtain convergence in the calculation
Charged particle multiplicities in deep inelastic scattering at HERA
International Nuclear Information System (INIS)
Aid, S.; Anderson, M.; Andreev, V.
1996-08-01
Using the H1 detector at HERA, charged particle multiplicity distributions in deep inelastic e + p scattering have been measured over a large kinematical region. The evolution with W and Q 2 of the multiplicity distribution and of the multiplicity moments in pseudorapidity domains of varying size is studied in the current fragmentation region of the hadronic centre-of-mass frame. The results are compared with data from fixed target lepton-nucleon interactions, e + e - annihilations and hadron-hadron collisions as well as with expectations from QCD based parton models. Fits to the negative binomial and lognormal distributions are presented. (orig.)
SWIMS, Sigmund and Winterbon Multiple Scattering of Ion Beams
International Nuclear Information System (INIS)
Eyeberger, L.
1999-01-01
1 - Description of program or function - SWIMS calculates the angular dispersion of ion beams that undergo small-angle, incoherent multiple scattering by gaseous or solid media. 2 - Method of solution - SWIMS uses the tabulated angular distributions of Sigmund and Winterbon for a Thomas-Fermi screened Coulomb potential. The fraction of the incident beam scattered into a cone defined by the polar angle is computed as a function of that angle for a reduced thickness over the rang of 0.01 to 10
Coastal Zone Color Scanner atmospheric correction algorithm - Multiple scattering effects
Gordon, Howard R.; Castano, Diego J.
1987-01-01
Errors due to multiple scattering which are expected to be encountered in application of the current Coastal Zone Color Scanner (CZCS) atmospheric correction algorithm are analyzed. The analysis is based on radiative transfer computations in model atmospheres, in which the aerosols and molecules are distributed vertically in an exponential manner, with most of the aerosol scattering located below the molecular scattering. A unique feature of the analysis is that it is carried out in scan coordinates rather than typical earth-sun coordinates, making it possible to determine the errors along typical CZCS scan lines. Information provided by the analysis makes it possible to judge the efficacy of the current algorithm with the current sensor and to estimate the impact of the algorithm-induced errors on a variety of applications.
Fiorino, Steven T.; Elmore, Brannon; Schmidt, Jaclyn; Matchefts, Elizabeth; Burley, Jarred L.
2016-05-01
Properly accounting for multiple scattering effects can have important implications for remote sensing and possibly directed energy applications. For example, increasing path radiance can affect signal noise. This study describes the implementation of a fast-calculating two-stream-like multiple scattering algorithm that captures azimuthal and elevation variations into the Laser Environmental Effects Definition and Reference (LEEDR) atmospheric characterization and radiative transfer code. The multiple scattering algorithm fully solves for molecular, aerosol, cloud, and precipitation single-scatter layer effects with a Mie algorithm at every calculation point/layer rather than an interpolated value from a pre-calculated look-up-table. This top-down cumulative diffusivity method first considers the incident solar radiance contribution to a given layer accounting for solid angle and elevation, and it then measures the contribution of diffused energy from previous layers based on the transmission of the current level to produce a cumulative radiance that is reflected from a surface and measured at the aperture at the observer. Then a unique set of asymmetry and backscattering phase function parameter calculations are made which account for the radiance loss due to the molecular and aerosol constituent reflectivity within a level and allows for a more accurate characterization of diffuse layers that contribute to multiple scattered radiances in inhomogeneous atmospheres. The code logic is valid for spectral bands between 200 nm and radio wavelengths, and the accuracy is demonstrated by comparing the results from LEEDR to observed sky radiance data.
Interstitial integrals in the multiple-scattering model
International Nuclear Information System (INIS)
Swanson, J.R.; Dill, D.
1982-01-01
We present an efficient method for the evaluation of integrals involving multiple-scattering wave functions over the interstitial region. Transformation of the multicenter interstitial wave functions to a single center representation followed by a geometric projection reduces the integrals to products of analytic angular integrals and numerical radial integrals. The projection function, which has the value 1 in the interstitial region and 0 elsewhere, has a closed-form partial-wave expansion. The method is tested by comparing its results with exact normalization and dipole integrals; the differences are 2% at worst and typically less than 1%. By providing an efficient means of calculating Coulomb integrals, the method allows treatment of electron correlations using a multiple scattering basis set
Multiple-scattering corrections to the Beer-Lambert law
International Nuclear Information System (INIS)
Zardecki, A.
1983-01-01
The effect of multiple scattering on the validity of the Beer-Lambert law is discussed for a wide range of particle-size parameters and optical depths. To predict the amount of received radiant power, appropriate correction terms are introduced. For particles larger than or comparable to the wavelength of radiation, the small-angle approximation is adequate; whereas for small densely packed particles, the diffusion theory is advantageously employed. These two approaches are used in the context of the problem of laser-beam propagation in a dense aerosol medium. In addition, preliminary results obtained by using a two-dimensional finite-element discrete-ordinates transport code are described. Multiple-scattering effects for laser propagation in fog, cloud, rain, and aerosol cloud are modeled
Quantum correlations induced by multiple scattering of quadrature squeezed light
DEFF Research Database (Denmark)
Lodahl, Peter
2006-01-01
Propagating quadrature squeezed light through a multiple scattering random medium is found to induce pronounced spatial quantum correlations that have no classical analogue. The correlations are revealed in the number of photons transported through the sample that can be measured from the intensity...... fluctuations of the total transmission or reflection. In contrast, no pronounced spatial quantum correlations appear in the quadrature amplitudes where excess noise above the shot noise level is found....
Multiple-scattering theory. New developments and applications
Energy Technology Data Exchange (ETDEWEB)
Ernst, Arthur
2007-12-04
Multiple-scattering theory (MST) is a very efficient technique for calculating the electronic properties of an assembly of atoms. It provides explicitly the Green function, which can be used in many applications such as magnetism, transport and spectroscopy. This work gives an overview on recent developments of multiple-scattering theory. One of the important innovations is the multiple scattering implementation of the self-interaction correction approach, which enables realistic electronic structure calculations of systems with localized electrons. Combined with the coherent potential approximation (CPA), this method can be applied for studying the electronic structure of alloys and as well as pseudo-alloys representing charge and spin disorder. This formalism is extended to finite temperatures which allows to investigate phase transitions and thermal fluctuations in correlated materials. Another novel development is the implementation of the self-consistent non-local CPA approach, which takes into account charge correlations around the CPA average and chemical short range order. This formalism is generalized to the relativistic treatment of magnetically ordered systems. Furthermore, several improvements are implemented to optimize the computational performance and to increase the accuracy of the KKR Green function method. The versatility of the approach is illustrated in numerous applications. (orig.)
Multiple-scattering theory. New developments and applications
International Nuclear Information System (INIS)
Ernst, Arthur
2007-01-01
Multiple-scattering theory (MST) is a very efficient technique for calculating the electronic properties of an assembly of atoms. It provides explicitly the Green function, which can be used in many applications such as magnetism, transport and spectroscopy. This work gives an overview on recent developments of multiple-scattering theory. One of the important innovations is the multiple scattering implementation of the self-interaction correction approach, which enables realistic electronic structure calculations of systems with localized electrons. Combined with the coherent potential approximation (CPA), this method can be applied for studying the electronic structure of alloys and as well as pseudo-alloys representing charge and spin disorder. This formalism is extended to finite temperatures which allows to investigate phase transitions and thermal fluctuations in correlated materials. Another novel development is the implementation of the self-consistent non-local CPA approach, which takes into account charge correlations around the CPA average and chemical short range order. This formalism is generalized to the relativistic treatment of magnetically ordered systems. Furthermore, several improvements are implemented to optimize the computational performance and to increase the accuracy of the KKR Green function method. The versatility of the approach is illustrated in numerous applications. (orig.)
Multiple Scattering Model for Optical Coherence Tomography with Rytov Approximation
Li, Muxingzi
2017-04-24
Optical Coherence Tomography (OCT) is a coherence-gated, micrometer-resolution imaging technique that focuses a broadband near-infrared laser beam to penetrate into optical scattering media, e.g. biological tissues. The OCT resolution is split into two parts, with the axial resolution defined by half the coherence length, and the depth-dependent lateral resolution determined by the beam geometry, which is well described by a Gaussian beam model. The depth dependence of lateral resolution directly results in the defocusing effect outside the confocal region and restricts current OCT probes to small numerical aperture (NA) at the expense of lateral resolution near the focus. Another limitation on OCT development is the presence of a mixture of speckles due to multiple scatterers within the coherence length, and other random noise. Motivated by the above two challenges, a multiple scattering model based on Rytov approximation and Gaussian beam optics is proposed for the OCT setup. Some previous papers have adopted the first Born approximation with the assumption of small perturbation of the incident field in inhomogeneous media. The Rytov method of the same order with smooth phase perturbation assumption benefits from a wider spatial range of validity. A deconvolution method for solving the inverse problem associated with the first Rytov approximation is developed, significantly reducing the defocusing effect through depth and therefore extending the feasible range of NA.
International Nuclear Information System (INIS)
Mayers, J.; Cywinski, R.
1985-03-01
Some of the approximations commonly used for the analytical estimation of multiple scattering corrections to thermal neutron elastic scattering data from cylindrical and plane slab samples have been tested using a Monte Carlo program. It is shown that the approximations are accurate for a wide range of sample geometries and scattering cross-sections. Neutron polarisation analysis provides the most stringent test of multiple scattering calculations as multiply scattered neutrons may be redistributed not only geometrically but also between the spin flip and non spin flip scattering channels. A very simple analytical technique for correcting for multiple scattering in neutron polarisation analysis has been tested using the Monte Carlo program and has been shown to work remarkably well in most circumstances. (author)
Multiple Scattering Approach to Continuum State with Generally Shaped Potential
International Nuclear Information System (INIS)
Hatada, Keisuke; Hayakawa, Kuniko; Tenore, Antonio; Benfatto, Maurizio; Natoli, Calogero
2007-01-01
We present a new scheme for solving the scattering problem for an arbitrarily shaped potential cell that avoids the well known convergence problems in the angular momentum expansion of the cell shape function. Tests of the method against analytically soluble separable model potentials, with and without shape truncation, have been performed with success. By a judicious choice of the shape of the cells partitioning the whole molecular space and use of empty cells when necessary, we set up a multiple scattering scheme that leads to a straightforward generalization of the same equations in the muffin-tin approximation. For example lmax in the angular momentum expansion can still be chosen according to the rule lmax ∼ kR, where R is the radius of the bounding sphere of the cell and all the matrices appearing in the theory are square matrices
Hatada, Keisuke; Ebert, Hubert
2018-01-01
This edited book, based on material presented at the EU Spec Training School on Multiple Scattering Codes and the following MSNano Conference, is divided into two distinct parts. The first part, subtitled “basic knowledge”, provides the basics of the multiple scattering description in spectroscopies, enabling readers to understand the physics behind the various multiple scattering codes available for modelling spectroscopies. The second part, “extended knowledge”, presents “state- of-the-art” short chapters on specific subjects associated with improving of the actual description of spectroscopies within the multiple scattering formalism, such as inelastic processes, or precise examples of modelling.
An integral for second-order multiple scattering perturbation theory
International Nuclear Information System (INIS)
Hoffman, G.G.
1997-01-01
This paper presents the closed form evaluation of a six-dimensional integral. The integral arises in the application to many-electron systems of a multiple scattering perturbation expansion at second order when formulated in fourier space. The resulting function can be used for the calculation of both the electron density and the effective one-electron potential in an SCF calculations. The closed form expression derived here greatly facilitates these calculations. In addition, the evaluated integral can be used for the computation of second-order corrections to the open-quotes optimized Thomas-Fermi theory.close quotes 10 refs., 2 figs
Quantum Interference and Entanglement Induced by Multiple Scattering of Light
DEFF Research Database (Denmark)
Ott, Johan Raunkjær; Mortensen, Asger; Lodahl, Peter
2010-01-01
We report on the effects of quantum interference induced by the transmission of an arbitrary number of optical quantum states through a multiple-scattering medium. We identify the role of quantum interference on the photon correlations and the degree of continuous variable entanglement between two...... output modes. It is shown that quantum interference survives averaging over all ensembles of disorder and manifests itself as increased photon correlations due to photon antibunching. Furthermore, the existence of continuous variable entanglement correlations in a volume speckle pattern is predicted. Our...
Aethalometer multiple scattering correction Cref for mineral dust aerosols
Di Biagio, Claudia; Formenti, Paola; Cazaunau, Mathieu; Pangui, Edouard; Marchand, Nicolas; Doussin, Jean-François
2017-08-01
In this study we provide a first estimate of the Aethalometer multiple scattering correction Cref for mineral dust aerosols. Cref is an empirical constant used to correct the aerosol absorption coefficient measurements for the multiple scattering artefact of the Aethalometer; i.e. the filter fibres on which aerosols are deposited scatter light and this is miscounted as absorption. The Cref at 450 and 660 nm was obtained from the direct comparison of Aethalometer data (Magee Sci. AE31) with (i) the absorption coefficient calculated as the difference between the extinction and scattering coefficients measured by a Cavity Attenuated Phase Shift Extinction analyser (CAPS PMex) and a nephelometer respectively at 450 nm and (ii) the absorption coefficient from a MAAP (Multi-Angle Absorption Photometer) at 660 nm. Measurements were performed on seven dust aerosol samples generated in the laboratory by the mechanical shaking of natural parent soils issued from different source regions worldwide. The single scattering albedo (SSA) at 450 and 660 nm and the size distribution of the aerosols were also measured. Cref for mineral dust varies between 1.81 and 2.56 for a SSA of 0.85-0.96 at 450 nm and between 1.75 and 2.28 for a SSA of 0.98-0.99 at 660 nm. The calculated mean for dust is 2.09 (±0.22) at 450 nm and 1.92 (±0.17) at 660 nm. With this new Cref the dust absorption coefficient by the Aethalometer is about 2 % (450 nm) and 11 % (660 nm) higher than that obtained by using Cref = 2.14 at both 450 and 660 nm, as usually assumed in the literature. This difference induces a change of up to 3 % in the dust SSA at 660 nm. The Cref seems to be independent of the fine and coarse particle size fractions, and so the obtained Cref can be applied to dust both close to sources and following transport. Additional experiments performed with pure kaolinite minerals and polluted ambient aerosols indicate Cref of 2.49 (±0.02) and 2.32 (±0.01) at 450 and 660 nm (SSA = 0.96-0.97) for
Muon energy estimate through multiple scattering with the MACRO detector
Energy Technology Data Exchange (ETDEWEB)
Ambrosio, M.; Antolini, R.; Auriemma, G.; Bakari, D.; Baldini, A.; Barbarino, G.C.; Barish, B.C.; Battistoni, G.; Becherini, Y.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bloise, C.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Candela, A.; Carboni, M.; Caruso, R.; Cassese, F.; Cecchini, S.; Cei, F.; Chiarella, V.; Choudhary, B.C.; Coutu, S.; Cozzi, M.; De Cataldo, G.; De Deo, M.; Dekhissi, H.; De Marzo, C.; De Mitri, I.; Derkaoui, J.; De Vincenzi, M.; Di Credico, A.; Dincecco, M.; Erriquez, O.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Gray, L.; Grillo, A.; Guarino, F.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Iarocci, E.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D.S.; Lindozzi, M.; Lipari, P.; Longley, N.P.; Longo, M.J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M.N.; Michael, D.G.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolo, D.; Nolty, R.; Orth, C.; Osteria, G.; Palamara, O.; Patera, V.; Patrizii, L.; Pazzi, R.; Peck, C.W.; Perrone, L.; Petrera, S.; Pistilli, P.; Popa, V.; Raino, A.; Reynoldson, J.; Ronga, F.; Rrhioua, A.; Satriano, C.; Scapparone, E. E-mail: eugenio.scapparone@bo.infn.it; Scholberg, K.; Sciubba, A.; Serra, P.; Sioli, M. E-mail: maximiliano.sioli@bo.infn.it; Sirri, G.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J.L.; Sulak, L.R.; Surdo, A.; Tarle, G.; Tatananni, E.; Togo, V.; Vakili, M.; Walter, C.W.; Webb, R
2002-10-21
Muon energy measurement represents an important issue for any experiment addressing neutrino-induced up-going muon studies. Since the neutrino oscillation probability depends on the neutrino energy, a measurement of the muon energy adds an important piece of information concerning the neutrino system. We show in this paper how the MACRO limited streamer tube system can be operated in drift mode by using the TDCs included in the QTPs, an electronics designed for magnetic monopole search. An improvement of the space resolution is obtained, through an analysis of the multiple scattering of muon tracks as they pass through our detector. This information can be used further to obtain an estimate of the energy of muons crossing the detector. Here we present the results of two dedicated tests, performed at CERN PS-T9 and SPS-X7 beam lines, to provide a full check of the electronics and to exploit the feasibility of such a multiple scattering analysis. We show that by using a neural network approach, we are able to reconstruct the muon energy for E{sub {mu}}<40 GeV. The test beam data provide an absolute energy calibration, which allows us to apply this method to MACRO data.
Muon energy estimate through multiple scattering with the MACRO detector
Ambrosio, M; Auriemma, G; Bakari, D; Baldini, A; Barbarino, G C; Barish, B C; Battistoni, G; Becherini, Y; Bellotti, R; Bemporad, C; Bernardini, P; Bilokon, H; Bloise, C; Bower, C; Brigida, M; Bussino, S; Cafagna, F; Calicchio, M; Campana, D; Candela, A; Carboni, M; Caruso, R; Cassese, F; Cecchini, S; Cei, F; Chiarella, V; Choudhary, B C; Coutu, S; Cozzi, M; De Cataldo, G; De Deo, M; Dekhissi, H; De Marzo, C; De Mitri, I; Derkaoui, J; De Vincenzi, M; Di Credico, A; Dincecco, M; Erriquez, O; Favuzzi, C; Forti, C; Fusco, P; Giacomelli, G; Giannini, G; Giglietto, N; Giorgini, M; Grassi, M; Gray, L; Grillo, A; Guarino, F; Gustavino, C; Habig, A; Hanson, K; Heinz, R; Iarocci, E; Katsavounidis, E; Katsavounidis, I; Kearns, E; Kim, H; Kyriazopoulou, S; Lamanna, E; Lane, C; Levin, D S; Lindozzi, M; Lipari, P; Longley, N P; Longo, M J; Loparco, F; Maaroufi, F; Mancarella, G; Mandrioli, G; Margiotta, A; Marini, A; Martello, D; Marzari-Chiesa, A; Mazziotta, M N; Michael, D G; Monacelli, P; Montaruli, T; Monteno, M; Mufson, S; Musser, J; Nicolò, D; Nolty, R; Orth, C; Osteria, G; Palamara, O; Patera, V; Patrizii, L; Pazzi, R; Peck, C W; Perrone, L; Petrera, S; Pistilli, P; Popa, V; Rainó, A; Reynoldson, J; Ronga, F; Rrhioua, A; Satriano, C; Scapparone, E; Scholberg, K; Sciubba, A; Serra, P; Sioli, M; Sirri, G; Sitta, M; Spinelli, P; Spinetti, M; Spurio, M; Steinberg, R; Stone, J L; Sulak, L R; Surdo, A; Tarle, G; Tatananni, E; Togo, V; Vakili, M; Walter, C W; Webb, R
2002-01-01
Muon energy measurement represents an important issue for any experiment addressing neutrino-induced up-going muon studies. Since the neutrino oscillation probability depends on the neutrino energy, a measurement of the muon energy adds an important piece of information concerning the neutrino system. We show in this paper how the MACRO limited streamer tube system can be operated in drift mode by using the TDCs included in the QTPs, an electronics designed for magnetic monopole search. An improvement of the space resolution is obtained, through an analysis of the multiple scattering of muon tracks as they pass through our detector. This information can be used further to obtain an estimate of the energy of muons crossing the detector. Here we present the results of two dedicated tests, performed at CERN PS-T9 and SPS-X7 beam lines, to provide a full check of the electronics and to exploit the feasibility of such a multiple scattering analysis. We show that by using a neural network approach, we are able to r...
A new three-dimensional track fit with multiple scattering
Energy Technology Data Exchange (ETDEWEB)
Berger, Niklaus; Kozlinskiy, Alexandr [Physikalisches Institut, Heidelberg University, Heidelberg (Germany); Institut für Kernphysik and PRISMA cluster of excellence, Mainz University, Mainz (Germany); Kiehn, Moritz; Schöning, André [Physikalisches Institut, Heidelberg University, Heidelberg (Germany)
2017-02-01
Modern semiconductor detectors allow for charged particle tracking with ever increasing position resolution. Due to the reduction of the spatial hit uncertainties, multiple Coulomb scattering in the detector layers becomes the dominant source for tracking uncertainties. In this case long distance effects can be ignored for the momentum measurement, and the track fit can consequently be formulated as a sum of independent fits to hit triplets. In this paper we present an analytical solution for a three-dimensional triplet(s) fit in a homogeneous magnetic field based on a multiple scattering model. Track fitting of hit triplets is performed using a linearization ansatz. The momentum resolution is discussed for a typical spectrometer setup. Furthermore the track fit is compared with other track fits for two different pixel detector geometries, namely the Mu3e experiment at PSI and a typical high-energy collider experiment. For a large momentum range the triplets fit provides a significantly better performance than a single helix fit. The triplets fit is fast and can easily be parallelized, which makes it ideal for the implementation on parallel computing architectures.
A new three-dimensional track fit with multiple scattering
International Nuclear Information System (INIS)
Berger, Niklaus; Kozlinskiy, Alexandr; Kiehn, Moritz; Schöning, André
2017-01-01
Modern semiconductor detectors allow for charged particle tracking with ever increasing position resolution. Due to the reduction of the spatial hit uncertainties, multiple Coulomb scattering in the detector layers becomes the dominant source for tracking uncertainties. In this case long distance effects can be ignored for the momentum measurement, and the track fit can consequently be formulated as a sum of independent fits to hit triplets. In this paper we present an analytical solution for a three-dimensional triplet(s) fit in a homogeneous magnetic field based on a multiple scattering model. Track fitting of hit triplets is performed using a linearization ansatz. The momentum resolution is discussed for a typical spectrometer setup. Furthermore the track fit is compared with other track fits for two different pixel detector geometries, namely the Mu3e experiment at PSI and a typical high-energy collider experiment. For a large momentum range the triplets fit provides a significantly better performance than a single helix fit. The triplets fit is fast and can easily be parallelized, which makes it ideal for the implementation on parallel computing architectures.
Fining of Red Wine Monitored by Multiple Light Scattering.
Ferrentino, Giovanna; Ramezani, Mohsen; Morozova, Ksenia; Hafner, Daniela; Pedri, Ulrich; Pixner, Konrad; Scampicchio, Matteo
2017-07-12
This work describes a new approach based on multiple light scattering to study red wine clarification processes. The whole spectral signal (1933 backscattering points along the length of each sample vial) were fitted by a multivariate kinetic model that was built with a three-step mechanism, implying (1) adsorption of wine colloids to fining agents, (2) aggregation into larger particles, and (3) sedimentation. Each step is characterized by a reaction rate constant. According to the first reaction, the results showed that gelatin was the most efficient fining agent, concerning the main objective, which was the clarification of the wine, and consequently the increase in its limpidity. Such a trend was also discussed in relation to the results achieved by nephelometry, total phenols, ζ-potential, color, sensory, and electronic nose analyses. Also, higher concentrations of the fining agent (from 5 to 30 g/100 L) or higher temperatures (from 10 to 20 °C) sped up the process. Finally, the advantage of using the whole spectral signal vs classical univariate approaches was demonstrated by comparing the uncertainty associated with the rate constants of the proposed kinetic model. Overall, multiple light scattering technique showed a great potential for studying fining processes compared to classical univariate approaches.
Qiu, Xiang; Dai, Ming; Yin, Chuan-li
2017-09-01
Unmanned aerial vehicle (UAV) remote imaging is affected by the bad weather, and the obtained images have the disadvantages of low contrast, complex texture and blurring. In this paper, we propose a blind deconvolution model based on multiple scattering atmosphere point spread function (APSF) estimation to recovery the remote sensing image. According to Narasimhan analytical theory, a new multiple scattering restoration model is established based on the improved dichromatic model. Then using the L0 norm sparse priors of gradient and dark channel to estimate APSF blur kernel, the fast Fourier transform is used to recover the original clear image by Wiener filtering. By comparing with other state-of-the-art methods, the proposed method can correctly estimate blur kernel, effectively remove the atmospheric degradation phenomena, preserve image detail information and increase the quality evaluation indexes.
Multiple Scattering in Random Mechanical Systems and Diffusion Approximation
Feres, Renato; Ng, Jasmine; Zhang, Hong-Kun
2013-10-01
This paper is concerned with stochastic processes that model multiple (or iterated) scattering in classical mechanical systems of billiard type, defined below. From a given (deterministic) system of billiard type, a random process with transition probabilities operator P is introduced by assuming that some of the dynamical variables are random with prescribed probability distributions. Of particular interest are systems with weak scattering, which are associated to parametric families of operators P h , depending on a geometric or mechanical parameter h, that approaches the identity as h goes to 0. It is shown that ( P h - I)/ h converges for small h to a second order elliptic differential operator on compactly supported functions and that the Markov chain process associated to P h converges to a diffusion with infinitesimal generator . Both P h and are self-adjoint (densely) defined on the space of square-integrable functions over the (lower) half-space in , where η is a stationary measure. This measure's density is either (post-collision) Maxwell-Boltzmann distribution or Knudsen cosine law, and the random processes with infinitesimal generator respectively correspond to what we call MB diffusion and (generalized) Legendre diffusion. Concrete examples of simple mechanical systems are given and illustrated by numerically simulating the random processes.
Real space multiple scattering description of alloy phase stability
International Nuclear Information System (INIS)
Turchi, P.E.A.; Sluiter, M.
1992-01-01
This paper presents a brief overview of the advanced methodology which has been recently developed to study phase stability properties of substitutional alloys, including order-disorder phenomena and structural transformations. The approach is based on the real space version of the Generalized Perturbation Method first introduced by Ducastelle and Gautier, within the Korringa-Kohn-Rostoker multiple scattering formulation of the Coherent Potential Approximation. Temperature effects are taken into account with a generalized meanfield approach, namely the Cluster Variation Method. The viability and the predictive power of such a scheme will be illustrated by a few examples, among them: the ground state properties of alloys, in particular the ordering tendencies for a series of equiatomic bcc-based alloys, the computation of alloy phase diagrams with the case of fcc and bcc-based Ni-Al alloys, the calculation of antiphase boundary energies and interfacial energies, and the stability of artificial ordered superlattices
Ultrafast collinear scattering and carrier multiplication in graphene.
Brida, D; Tomadin, A; Manzoni, C; Kim, Y J; Lombardo, A; Milana, S; Nair, R R; Novoselov, K S; Ferrari, A C; Cerullo, G; Polini, M
2013-01-01
Graphene is emerging as a viable alternative to conventional optoelectronic, plasmonic and nanophotonic materials. The interaction of light with charge carriers creates an out-of-equilibrium distribution, which relaxes on an ultrafast timescale to a hot Fermi-Dirac distribution, that subsequently cools emitting phonons. Although the slower relaxation mechanisms have been extensively investigated, the initial stages still pose a challenge. Experimentally, they defy the resolution of most pump-probe setups, due to the extremely fast sub-100 fs carrier dynamics. Theoretically, massless Dirac fermions represent a novel many-body problem, fundamentally different from Schrödinger fermions. Here we combine pump-probe spectroscopy with a microscopic theory to investigate electron-electron interactions during the early stages of relaxation. We identify the mechanisms controlling the ultrafast dynamics, in particular the role of collinear scattering. This gives rise to Auger processes, including charge multiplication, which is key in photovoltage generation and photodetectors.
Radiation of ultrarelativistic charge taking into account for multiple scattering
International Nuclear Information System (INIS)
Yang, C.
1977-01-01
A brief theoretical review of characteristics of X-rays and more hard radiation formed by an ultrarelativistic charged particle passing through a plate or a stack of plates with regard for multiple scattering and the plate material absorptivity is made. Formulas for frequency- angular and frequency distributions of total radiation in the cases of a plate and of a stack of plates with large spacings as well as a stack of sufficiently thick plates are given. A calculation method for the radiation distributions in a general case of an arbitrary stack is pointed out. The frequency distribution of the total radiation consisting of bremsstrahlung and boundary effects is analyzed in detail. A problem of experimental separation of the boundary effect from the total radiation is discussed
Multiple scattering of slow muons in an electron gas
International Nuclear Information System (INIS)
Archubi, C.D.; Arista, N.R.
2017-01-01
A comparative study of the angular dispersion of slow muons in an electron gas is performed using 3 dielectric models which represent the case of metals (Lindhard model for a free electron gas) and the cases of semiconductors and insulators (Levine and Louie model and Brandt and Reinheimer model for systems with a band gap) and a non-linear model for both cases at very low velocities. The contribution of collective electronic excitations according to the dielectric model are found to be negligible. The results from the calculation using Lindhard expressions for the angular half width are consistent with the result of a multiple scattering model. In particular, the effects produced by the band gap of the material are analyzed in detail. Finally, as the recoil effect is negligible, there is an almost exact scaling, for a given velocity, between the proton and the muon results. (authors)
Study of the multiple scattering effect in TEBENE using the Monte Carlo method
International Nuclear Information System (INIS)
Singkarat, Somsorn.
1990-01-01
The neutron time-of-flight and energy spectra, from the TEBENE set-up, have been calculated by a computer program using the Monte Carlo method. The neutron multiple scattering within the polyethylene scatterer ring is closely investigated. The results show that multiple scattering has a significant effect on the detected neutron yield. They also indicate that the thickness of the scatterer ring has to be carefully chosen. (author)
Characterization of the Lung Parenchyma Using Ultrasound Multiple Scattering.
Mohanty, Kaustav; Blackwell, John; Egan, Thomas; Muller, Marie
2017-05-01
The purpose of the study described here was to showcase the application of ultrasound to quantitative characterization of the micro-architecture of the lung parenchyma to predict the extent of pulmonary edema. The lung parenchyma is a highly complex and diffusive medium for which ultrasound techniques have remained qualitative. The approach presented here is based on ultrasound multiple scattering and exploits the complexity of ultrasound propagation in the lung structure. The experimental setup consisted of a linear transducer array with an 8-MHz central frequency placed in contact with the lung surface. The diffusion constant D and transport mean free path L* of the lung parenchyma were estimated by separating the incoherent and coherent intensities in the near field and measuring the growth of the incoherent diffusive halo over time. Significant differences were observed between the L* values obtained in healthy and edematous rat lungs in vivo. In the control rat lung, L* was found to be 332 μm (±48.8 μm), whereas in the edematous lung, it was 1040 μm (±90 μm). The reproducibility of the measurements of L* and D was tested in vivo and in phantoms made of melamine sponge with varying air volume fractions. Two-dimensional finite difference time domain numerical simulations were carried out on rabbit lung histology images with varying degrees of lung collapse. Significant correlations were observed between air volume fraction and L* in simulation (r = -0.9542, p lung in which edema was simulated by adding phosphate-buffered saline revealed a linear relationship between the fluid volume fraction and L*. These results illustrate the potential of methods based on ultrasound multiple scattering for the quantitative characterization of the lung parenchyma. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
Aethalometer multiple scattering correction Cref for mineral dust aerosols
Directory of Open Access Journals (Sweden)
C. Di Biagio
2017-08-01
Full Text Available In this study we provide a first estimate of the Aethalometer multiple scattering correction Cref for mineral dust aerosols. Cref is an empirical constant used to correct the aerosol absorption coefficient measurements for the multiple scattering artefact of the Aethalometer; i.e. the filter fibres on which aerosols are deposited scatter light and this is miscounted as absorption. The Cref at 450 and 660 nm was obtained from the direct comparison of Aethalometer data (Magee Sci. AE31 with (i the absorption coefficient calculated as the difference between the extinction and scattering coefficients measured by a Cavity Attenuated Phase Shift Extinction analyser (CAPS PMex and a nephelometer respectively at 450 nm and (ii the absorption coefficient from a MAAP (Multi-Angle Absorption Photometer at 660 nm. Measurements were performed on seven dust aerosol samples generated in the laboratory by the mechanical shaking of natural parent soils issued from different source regions worldwide. The single scattering albedo (SSA at 450 and 660 nm and the size distribution of the aerosols were also measured. Cref for mineral dust varies between 1.81 and 2.56 for a SSA of 0.85–0.96 at 450 nm and between 1.75 and 2.28 for a SSA of 0.98–0.99 at 660 nm. The calculated mean for dust is 2.09 (±0.22 at 450 nm and 1.92 (±0.17 at 660 nm. With this new Cref the dust absorption coefficient by the Aethalometer is about 2 % (450 nm and 11 % (660 nm higher than that obtained by using Cref = 2.14 at both 450 and 660 nm, as usually assumed in the literature. This difference induces a change of up to 3 % in the dust SSA at 660 nm. The Cref seems to be independent of the fine and coarse particle size fractions, and so the obtained Cref can be applied to dust both close to sources and following transport. Additional experiments performed with pure kaolinite minerals and polluted ambient aerosols indicate Cref of 2.49 (±0.02 and 2
Multiple exchange and high-energy fixed-angle scattering
Halliday, I G; Orzalesi, C A; Tau, M
1975-01-01
The application of the eikonal ansatz to fermion fermion elastic scattering with Abelian vector gluon exchanges is discussed. The behaviours of the elastic scattering amplitude and the elastic form factor are considered and an important mechanism for fixed angle high energy elastic scattering is identified. (6 refs).
Jeong, Seungwon; Lee, Ye-Ryoung; Choi, Wonjun; Kang, Sungsam; Hong, Jin Hee; Park, Jin-Sung; Lim, Yong-Sik; Park, Hong-Gyu; Choi, Wonshik
2018-05-01
The efficient delivery of light energy is a prerequisite for the non-invasive imaging and stimulating of target objects embedded deep within a scattering medium. However, the injected waves experience random diffusion by multiple light scattering, and only a small fraction reaches the target object. Here, we present a method to counteract wave diffusion and to focus multiple-scattered waves at the deeply embedded target. To realize this, we experimentally inject light into the reflection eigenchannels of a specific flight time to preferably enhance the intensity of those multiple-scattered waves that have interacted with the target object. For targets that are too deep to be visible by optical imaging, we demonstrate a more than tenfold enhancement in light energy delivery in comparison with ordinary wave diffusion cases. This work will lay a foundation to enhance the working depth of imaging, sensing and light stimulation.
DEFF Research Database (Denmark)
Kristensen, Philip Trøst; Lodahl, Peter; Mørk, Jesper
2010-01-01
We present an accurate, stable, and efficient solution to the Lippmann–Schwinger equation for electromagnetic scattering in two dimensions. The method is well suited for multiple scattering problems and may be applied to problems with scatterers of arbitrary shape or non-homogenous background mat...
Measurements and applications of neutron multiple scattering in resonance region
International Nuclear Information System (INIS)
Ohkubo, Makio
1977-02-01
Capture yield of neutrons impinging on a thick material is complicated due to self-shielding and multiple scattering, especially in the resonance region. When the incident neutron energy is equal to a resonance energy of the material, capture probability of the neutron increases with sample thickness and reaches a saturation value P sub(CO). There is a simple relation between P sub(CO) and GAMMA sub(n)/GAMMA and the recoil energy by the Monte-Carlo calculation. To examine validity of the relation, P sub(CO) was measured for 19 resonances in 12 nuclides with thick samples, using a JAERI linac time-of-flight spectrometer with Moxon-Rae type gamma ray detector and transmission type neutron flux monitor. Results of the measurements confirmed the validity. With this relation, the GAMMA sub(n)/GAMMA or GAMMA sub(γ)/GAMMA value can be obtained from the measured P sub(CO), and also the level spins be determined by combining the transmission data. Because of the definition of P sub(CO), determination of the resonance parameters is not sensitive to the sample thickness as far as it is sufficiently thick. (auth.)
Multiple-scattering theory with a truncated basis set
International Nuclear Information System (INIS)
Zhang, X.; Butler, W.H.
1992-01-01
Multiple-scattering theory (MST) is an extremely efficient technique for calculating the electronic structure of an assembly of atoms. The wave function in MST is expanded in terms of spherical waves centered on each atom and indexed by their orbital and azimuthal quantum numbers, l and m. The secular equation which determines the characteristic energies can be truncated at a value of the orbital angular momentum l max , for which the higher angular momentum phase shifts, δ l (l>l max ), are sufficiently small. Generally, the wave-function coefficients which are calculated from the secular equation are also truncated at l max . Here we point out that this truncation of the wave function is not necessary and is in fact inconsistent with the truncation of the secular equation. A consistent procedure is described in which the states with higher orbital angular momenta are retained but with their phase shifts set to zero. We show that this treatment gives smooth, continuous, and correctly normalized wave functions and that the total charge density calculated from the corresponding Green function agrees with the Lloyd formula result. We also show that this augmented wave function can be written as a linear combination of Andersen's muffin-tin orbitals in the case of muffin-tin potentials, and can be used to generalize the muffin-tin orbital idea to full-cell potentals
Multiple scattering approach to the vibrational excitation of molecules by slow electrons
International Nuclear Information System (INIS)
Drukarev, G.
1976-01-01
Another approach to the problem of vibrational excitation of homonuclear two-atomic molecules by slow electrons possibly accompanied by rotational transitions is presented based on the picture of multiple scattering of an electron inside the molecule. The scattering of two fixed centers in the zero range potential model is considered. The results indicate that the multiple scattering determines the order of magnitude of the vibrational excitation cross sections in the energy region under consideration even if the zero range potential model is used. Also the connection between the multiple scattering approach and quasi-stationary molecular ion picture is established. 9 refs
Absorption in multiple scattering systems of coated spheres: design applications
International Nuclear Information System (INIS)
Stout, Brian; Andraud, Christine; Stout, Sophie; Lafait, Jacques
2003-01-01
We illustrate the utility of some recently derived transfer matrix methods for electromagnetic scattering calculations in systems composed of coated spherical scatterers. Any of the spherical coatings, cores, or host media may be composed of absorbing materials. Our formulae permit the calculation of local absorption in either orientation fixed or orientation averaged situations. We introduce methods for estimating the macroscopic transport properties of such media, and show how our scattering calculations can permit 'design' optimization of macroscopic properties
Evanescent wave scattering at off-axis incidence on multiple cylinders located near a surface
International Nuclear Information System (INIS)
Lee, Siu-Chun
2015-01-01
The scattering characteristics of an infinite cylinder are strongly influenced by the incidence angle relative to its axis. If the incident wave propagates in the plane normal to the axis of the cylinder, the polarization of the scattered wave remains unchanged and the scattered wave propagates in the same plan as the incident wave. At off-axis incidence such that the incident direction makes an oblique angle with the cylinder axis, the scattered wave is depolarized, and its spatial distribution becomes three-dimensional. This paper presents the scattering solution for oblique incidence on multiple parallel cylinders located near a planar interface by an evanescent wave that is generated by total internal reflection of the source wave propagating in the higher refractive index substrate. Hertz potentials are utilized to formulate the interaction of inhomogeneous waves with the cylinders, scattering at the substrate interface, and near field scattering between the cylinders. Analytic formulas are derived for the electromagnetic fields and Poynting vector of scattered radiation in the near-field and their asymptotic forms in the far-field. Numerical examples are shown to illustrate scattering of evanescent wave by multiple cylinders at off-axis incidence. - Highlights: • Developed an exact solution for off-axis incidence on multiple cylinders. • Included depolarization, near-field scattering, and Fresnel effect in theory. • Derived analytic formulas for scattered radiation in the far field. • Illustrated evanescent scattering at off-axis incidence by numerical data
International Nuclear Information System (INIS)
Margetan, F.J.; Haldipur, Pranaam; Yu Linxiao; Thompson, R.B.
2005-01-01
For pulse/echo inspections of metals, models which predict backscattered noise characteristics often make a 'single-scattering' assumption, i.e., multiple-scattering events in which sound is scattered from one grain to another before returning to the transducer are ignored. Models based on the single-scattering assumption have proven to be very useful in simulating inspections of engine-alloy billets and forgings. However, this assumption may not be accurate if grain scattering is too 'strong' (e.g., if the mean grain diameter and/or the inspection frequency is too large). In this work, backscattered grain noise measurements and analyses were undertaken to search for evidence of significant multiple scattering in pulse/echo inspections of jet-engine Nickel alloys. At or above about 7 MHz frequency and 50 micron grain diameter, problems were seen with single-scattering noise models that are likely due to the neglect of multiple scattering by the models. The modeling errors were less severe for focused-probe measurements in the focal zone than for planar probe inspections. Single-scattering noise models are likely adequate for simulating current billet inspections which are carried out using 5-MHz focused transducers. However, multiple scattering effects should be taken into account in some fashion when simulating higher-frequency inspections of Nickel-alloy billets having large mean grain diameters (> 40 microns)
Exact multiple scattering theory of two-nucleus collisions including the Pauli principle
International Nuclear Information System (INIS)
Gurvitz, S.A.
1981-01-01
Exact equations for two-nucleus scattering are derived in which the effects of the Pauli principle are fully included. Our method exploits a modified equation for the scattering of two identical nucleons, which is obtained at the beginning. Considering proton-nucleus scattering we found that the resulting amplitude has two components, one resembling a multiple scattering series for distinguishable particles, and the other a distorted (A-1) nucleon cluster exchange. For elastic pA scattering the multiple scattering amplitude is found in the form of an optical potential expansion. We show that the Kerman-McManus-Thaler theory of the optical potential could be easily modified to include the effects of antisymmetrization of the projectile with the target nucleons. Nucleus-nucleus scattering is studied first for distinguishable target and beam nucleus. Afterwards the Pauli principle is included, where only the case of deuteron-nucleus scattering is discussed in detail. The resulting amplitude has four components. Two of them correspond to modified multiple scattering expansions and the others are distorted (A-1)- and (A-2)- nucleon cluster exchange. The result for d-A scattering is extended to the general case of nucleus-nucleus scattering. The equations are simple to use and as such constitute an improvement over existing schemes
Single and multiple electromagnetic scattering by dielectric obstacles from a resonance perspective
International Nuclear Information System (INIS)
Riley, D.J.
1987-03-01
A new application of the singularity expansion method (SEM) is explored. This application combines the classical theory of wave propagation through a multiple-scattering environment and the SEM. Because the SEM is generally considered to be a theory for describing surface currents on conducting scatters, extensions are made which permit, under certain conditions, a singularity expansion representation for the electromagnetic field scattered by a dielectric scatterer. Application of this expansion is then made to the multiple-scattering case using both single and multiple interactions. A resonance scattering tensor form is used for the SEM description which leds to an associated tensor form for the solution to the multiple-scattering problem with each SEM pole effect appearing explicitly. The coherent field is determined for both spatial and SEM parameter random variations. A numerical example for the case of an ensemble of dielectric spheres which possess frequency-dependent loss is also made. Accurate resonance expansions for the single-scattering problem are derived, and resonance trajectories based on the Debye relaxation model for the refractive index are introduced. Application of these resonance expansions is then made to the multiple-scattering results for a slab containing a distribution of spheres with varying radii. Conditions are discussed which describe when the hybrid theory is appropriate. 53 refs., 21 figs., 9 tabs
Elastic and quasielastic scattering of light nuclei in the theory of multiple scattering
International Nuclear Information System (INIS)
Ismatov, E.I.; Kuterbekov, K.A.; Dzhuraev, Sh.Kh.; Ehsaniyazov, Sh.P.; Zholdasova, S.M.
2005-01-01
In the work the calculation method for diffraction scattering amplitudes of light nuclei by heavy nuclei is developed. For A 1 A 2 -scattering effects of pair-, three-fold, and four-fold screenings are estimated. It is shown, that in amplitude calculations for A 1 A 2 elastic scattering it is enough come to nothing more than accounting of total screenings in the first order. Analysis of nucleus-nucleus scattering sensitive characteristics to choice of single-particle nuclear densities parametrization is carried out
Multiple scattering of polarized light: comparison of Maxwell theory and radiative transfer theory.
Voit, Florian; Hohmann, Ansgar; Schäfer, Jan; Kienle, Alwin
2012-04-01
For many research areas in biomedical optics, information about scattering of polarized light in turbid media is of increasing importance. Scattering simulations within this field are mainly performed on the basis of radiative transfer theory. In this study a polarization sensitive Monte Carlo solution of radiative transfer theory is compared to exact Maxwell solutions for all elements of the scattering Müller matrix. Different scatterer volume concentrations are modeled as a multitude of monodisperse nonabsorbing spheres randomly positioned in a cubic simulation volume which is irradiated with monochromatic incident light. For all Müller matrix elements effects due to dependent scattering and multiple scattering are analysed. The results are in overall good agreement between the two methods with deviations related to dependent scattering being prominent for high volume concentrations and high scattering angles.
Multiple pole in the electron--hydrogen-atom scattering amplitude
International Nuclear Information System (INIS)
Amusia, M.Y.; Kuchiev, M.Y.
1982-01-01
It is demonstrated that the amplitude for electron--hydrogen-atom forward scattering has the third-order pole at the point E = -13.6 eV, E being the energy of the incident electron. The coefficients which characterize the pole are calculated exactly. The invalidity of the Born approximation is proved. The contribution of the pole singularity to the dispersion relation for the scattering amplitude is discussed
International Nuclear Information System (INIS)
Papiez, L.; Moskvin, V.; Tulovsky, V.
2001-01-01
The process of angular-spatial evolution of multiple scattering of charged particles can be described by a special case of Boltzmann integro-differential equation called Lewis equation. The underlying stochastic process for this evolution is the compound Poisson process on the surface of the unit sphere. The significant portion of events that constitute compound Poisson process that describes multiple scattering have diffusional character. This property allows to analyze the process of angular-spatial evolution of multiple scattering of charged particles as combination of soft and hard collision processes and compute appropriately its transition densities. These computations provide a method of the approximate solution to the Lewis equation. (orig.)
Observation of spatial quantum correlations induced by multiple scattering of nonclassical light
DEFF Research Database (Denmark)
Smolka, Stephan; Huck, Alexander; Andersen, Ulrik Lund
2009-01-01
and negative spatial quantum correlations are observed when varying the quantum state incident to the multiple scattering medium, and the strength of the correlations is controlled by the number of photons. The experimental results are in excellent agreement with recent theoretical proposals by implementing......We present the experimental realization of spatial quantum correlations of photons that are induced by multiple scattering of squeezed light. The quantum correlation relates photons propagating along two different light paths through the random medium and is infinite in range. Both positive...... the full quantum model of multiple scattering....
Density of states calculations and multiple-scattering theory for photons
International Nuclear Information System (INIS)
Moroz, A.
1994-05-01
The density of states for a finite or an infinite cluster of scatterers in the case of both, electrons and photons, can be represented in a general form as the sum over all Krein-Friedel contributions of individual scatterers and a contribution due to the presence of multiple scatterers. The latter is given by the sum over all periodic orbits between different scatterers. General three dimensional multiple-scattering theory for electromagnetic waves in the presence of scatterers of arbitrary shape is presented. Vector structure constants are calculated and general rules for obtaining them from known scalar structure constants are given. The KKR equations for photons are explicitly written down. (author). 22 refs., 2 figs
Energy Technology Data Exchange (ETDEWEB)
Gorodnichev, E. E., E-mail: gorodn@theor.mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation)
2016-12-15
For elliptically polarized light incident on a two-dimensional medium with large inhomogeneities, the Stokes parameters of scattered waves are calculated. Multiple scattering is assumed to be sharply anisotropic. The degree of polarization of scattered radiation is shown to be a nonmonotonic function of depth when the incident wave is circularly polarized or its polarization vector is not parallel to the symmetry axis of the inhomogeneities.
Rakotonarivo , Sandrine; Walker , S.C.; Kuperman , W. A.; Roux , Philippe
2011-01-01
International audience; A method to actively localize a small perturbation in a multiple scattering medium using a collection of remote acoustic sensors is presented. The approach requires only minimal modeling and no knowledge of the scatterer distribution and properties of the scattering medium and the perturbation. The medium is ensonified before and after a perturbation is introduced. The coherent difference between the measured signals then reveals all field components that have interact...
Solution of neutron slowing down equation including multiple inelastic scattering
International Nuclear Information System (INIS)
El-Wakil, S.A.; Saad, A.E.
1977-01-01
The present work is devoted the presentation of an analytical method for the calculation of elastically and inelastically slowed down neutrons in an infinite non absorbing homogeneous medium. On the basis of the Central limit theory (CLT) and the integral transform technique the slowing down equation including inelastic scattering in terms of the Green function of elastic scattering is solved. The Green function is decomposed according to the number of collisions. A formula for the flux at any lethargy O (u) after any number of collisions is derived. An equation for the asymptotic flux is also obtained
Optimum track fitting in the presence of multiple scattering
International Nuclear Information System (INIS)
Lutz, G.
1987-06-01
A method for track fitting is proposed which attempts to be as close as possible to the real track along the full path length. This is done by the introduction of scattering planes in which the particle is allowed to change its direction. A fit over the full track length includes the probability of direction change by scattering. Using matrix notation a fairly simple formalism for error estimation has been developed. Results of this method are compared to those of more widely used procedures for 'typical' examples of High Energy Spectrometers. (orig.)
Eikonal multiple scattering model within the framework of Feynman's positron theory
International Nuclear Information System (INIS)
Tekou, A.
1986-07-01
The Bethe Salpeter equation for nucleon-nucleon, nucleon-nucleus and nucleus-nucleus scattering is eikonalized. Multiple scattering series is obtained. Contributions of three body interations are included. The model presented below may be used to investigate atomic collisions. (author)
DEFF Research Database (Denmark)
de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper
2012-01-01
We present a multiple-scattering formalism for simulating scattering of electromagnetic waves on spherical inhomogeneities in 3D. The formalism is based on the Lippmann-Schwinger equation and the electromagnetic Green's tensor and applies an expansion of the electric field on spherical...
Multiple scattering theory for non-local and multichannel potentials
Czech Academy of Sciences Publication Activity Database
Natoli, C.R.; Krüger, P.; Hatada, K.; Hayakawa, K.; Sébilleau, D.; Šipr, Ondřej
2012-01-01
Roč. 24, č. 36 (2012), s. 1-20 ISSN 0953-8984 Institutional research plan: CEZ:AV0Z10100521 Keywords : multichannel scattering * correlation s * density matrix Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.355, year: 2012
Application of multiple scattering theory in electron dosimetry
International Nuclear Information System (INIS)
Oliveira, M.J.G.S. de.
1984-01-01
A theoretical model, based on the Fermi-Eyges scattering theory, which takes into account the different heterogeneous media, is proposed. Heterogeneous phantoms were built in order to obtain curves of distribution of the absorbed dose. The agreement between the theoretical and experimental data prove that presented theory model is useful to describe the absorbed dose in homogeneous media. (M.A.C.) [pt
Continuum and bound electronic wavefunctions for anisotropic multiple-scattering potentials
International Nuclear Information System (INIS)
Siegel, J.; Dill, D.; Dehmer, J.L.
1975-01-01
Standard multiple-scattering treatments of bound and continuum one-electron states are restricted to a monopole potential in each of the various spherical regions. We have extended the treatment within these regions to a general potential. The corresponding multiple-scattering equations should facilitate accurate treatment of effects of the build-up of charge due to bonding, of the dipole character of polar molecules, and of external fields
Multiple scattering corrections to the Beer-Lambert law. 1: Open detector.
Tam, W G; Zardecki, A
1982-07-01
Multiple scattering corrections to the Beer-Lambert law are analyzed by means of a rigorous small-angle solution to the radiative transfer equation. Transmission functions for predicting the received radiant power-a directly measured quantity in contrast to the spectral radiance in the Beer-Lambert law-are derived. Numerical algorithms and results relating to the multiple scattering effects for laser propagation in fog, cloud, and rain are presented.
Multiple factors affecting South African anchovy recruitment in the ...
African Journals Online (AJOL)
Multiple factors affecting South African anchovy recruitment in the spawning, transport and nursery. ... and are inversely linked to high rates of gonad atresia in anchovy and reduced subsequent recruitment. ... AJOL African Journals Online.
[Multiple scattering of visible and infrared light by sea fog over wind driving rough sea surface].
Sun, Xian-Ming; Wang, Hai-Hua; Lei, Cheng-Xin; Shen, Jin
2013-08-01
The present paper is concerned with computing the multiple scattering characteristics of a sea fog-sea surface couple system within this context. The single scattering characteristics of sea fog were studied by Mie theory, and the multiple scattering of sunlight by single sea fog layer was studied by radiative transfer theory. The reflection function of a statistically rough ocean surface was obtained using the standard Kirchhoff formulation, with shadowing effects taken into account. The reflection properties of the combined sea fog and ocean surface were obtained employing the adding method, and the results indicated that the reflected light intensity of sea fog increased with the sea background.
Coherent transmission of an ultrasonic shock wave through a multiple scattering medium.
Viard, Nicolas; Giammarinaro, Bruno; Derode, Arnaud; Barrière, Christophe
2013-08-01
We report measurements of the transmitted coherent (ensemble-averaged) wave resulting from the interaction of an ultrasonic shock wave with a two-dimensional random medium. Despite multiple scattering, the coherent waveform clearly shows the steepening that is typical of nonlinear harmonic generation. This is taken advantage of to measure the elastic mean free path and group velocity over a broad frequency range (2-15 MHz) in only one experiment. Experimental results are found to be in good agreement with a linear theoretical model taking into account spatial correlations between scatterers. These results show that nonlinearity and multiple scattering are both present, yet uncoupled.
Concise formulation of the three-dimensional multiple-scattering theory.
Oyhenart, Laurent; Vignéras, Valérie
2012-08-01
The scattering of an electromagnetic wave by a set of dielectric and metallic spheres is a well-known physical problem. We show a mathematical simplification of the multiple-scattering theory. In this paper, we will establish the multiple-scattering equation in two different ways. Through the study of the equation form, we can choose the simplest spherical wave expansion for calculations. Then, we propose concise expressions of the Mie scattering coefficients and translation coefficients for both polarizations. With these simplified expressions, large spheres are studied without loss of accuracy. Far-field expressions, cross-sections, and the scattering matrix are also simplified. Thus, we obtain formulas that can be easily understood from a physical point of view.
Multiple scattering in closely packed systems of arbitrary non-overlapping shapes
International Nuclear Information System (INIS)
Keister, B.D.
1982-11-01
It has long been known that the multiple scattering of waves from a system of obstacles of finite extent can be described completely with a knowledge of the on-shell amplitudes of the individual scatterers, provided that the minimally enclosing spheres concentric with the scattering centers do not overlap. In this paper, it is shown that on-shell amplitudes alone suffice for a wider class of scattering configurations, in which the individual scatterers do not overlap, but their geometries do not satisfy the above condition. These extended geometries require a careful treatment of certain partial wave sums. An example is also discussed in which a pair of non-overlapping scatterers requires more than the on-shell amplitudes for a solution
Ground Vibration Isolation of Multiple Scattering by Using Rows of Tubular Piles as Barriers
Directory of Open Access Journals (Sweden)
Miao-miao Sun
2014-01-01
Full Text Available A new formal solution for the multiple scattering of plane harmonic waves by a group of arbitrary configuration tubular piles in an elastic total space is derived. Each order of scattering satisfies prescribed boundary conditions at the interface of tubular piles, which is delivered as the sum of incident and scattering waves. The first order performs the scattering wave by each scattered pile and the subsequent orders resulted from the excitation of each pile of first order of scattering from the remaining tubular piles. Advanced scattering orders can be regarded as the same manners. Several series of scattering coefficients are figured out with the aids of addition theorem so that the exact steady-state solution for the scattered displacement and stress is obtained. Particularly, when internal diameter of tubular piles tends to be infinitely small, it degenerates to a solid pile problem. By imposing the normalized displacement amplitudes and transmissibility indices, the influences of specific parameters such as scattering orders, internal and external diameter ratio of piles, pile material rigidity, position and distances between tubular pile and pile rows, and pile numbers are discussed. Certain recommended conclusions have been drawn as the guidelines of practical engineering design for discontinuous barrier of tubular piles.
Inelastic multiple scattering of interacting bosons in weak random potentials
International Nuclear Information System (INIS)
Geiger, Tobias
2013-01-01
Within the present thesis we develop a diagrammatic scattering theory for interacting bosons in a three-dimensional, weakly disordered potential. Based on a microscopic N-body scattering theory, we identify the relevant diagrams including elastic and inelastic collision processes that are sufficient to describe quantum transport in the regime of weak disorder. By taking advantage of the statistical properties of the weak disorder potential, we demonstrate how the N-body dynamics can be reduced to a nonlinear integral equation of Boltzmann type for the single-particle diffusive flux. A presently available alternative description - based on the Gross-Pitaevskii equation - only includes elastic collisions. In contrast, we show that far from equilibrium the presence of inelastic collisions - even for weak interaction strength - must be accounted for and can induce the full thermalization of the single-particle current. In addition, we also determine the coherent corrections to the incoherent transport, leading to the effect of coherent backscattering. For the first time, we are able to analyze the influence of inelastic collisions on the coherent backscattering signal, which lead to an enhancement of the backscattered cone in a narrow spectral window, even for increasing non-linearity. With a short recollection of the presently available experimental techniques we furthermore show how an immediate implementation of our suggested setup with confined Bose-Einstein condensates can be accomplished. Thereby, the emergence of collective and/or thermodynamic behavior from fundamental, microscopic constituents can also be assessed experimentally. In a second part of this thesis, we present first results for light scattering off strongly interacting Rydberg atoms trapped in a one-dimensional, chain-like configuration. In order to monitor the time-dependence of this interacting many-body system, we devise a weak measurement scenario for which we derive a master equation for the
In vivo diagnosis of skin cancer using polarized and multiple scattered light spectroscopy
Bartlett, Matthew Allen
This thesis research presents the development of a non-invasive diagnostic technique for distinguishing between skin cancer, moles, and normal skin using polarized and multiple scattered light spectroscopy. Polarized light incident on the skin is single scattered by the epidermal layer and multiple scattered by the dermal layer. The epidermal light maintains its initial polarization while the light from the dermal layer becomes randomized and multiple scattered. Mie theory was used to model the epidermal light as the scattering from the intercellular organelles. The dermal signal was modeled as the diffusion of light through a localized semi-homogeneous volume. These models were confirmed using skin phantom experiments, studied with in vitro cell cultures, and applied to human skin for in vivo testing. A CCD-based spectroscopy system was developed to perform all these experiments. The probe and the theory were tested on skin phantoms of latex spheres on top of a solid phantom. We next extended our phantom study to include in vitro cells on top of the solid phantom. Optical fluorescent microscope images revealed at least four distinct scatterers including mitochondria, nucleoli, nuclei, and cell membranes. Single scattering measurements on the mammalian cells consistently produced PSD's in the size range of the mitochondria. The clinical portion of the study consisted of in vivo measurements on cancer, mole, and normal skin spots. The clinical study combined the single scattering model from the phantom and in vitro cell studies with the diffusion model for multiple scattered light. When parameters from both layers were combined, we found that a sensitivity of 100% and 77% can be obtained for detecting cancers and moles, respectively, given the number of lesions examined.
Coherence effects and average multiplicity in deep inelastic scattering at small χ
International Nuclear Information System (INIS)
Kisselev, A.V.; Petrov, V.A.
1988-01-01
The average hadron multiplicity in deep inelastic scattering at small χ is calculated in this paper. Its relationship with the average multiplicity in e + e - annihilation is established. As shown the results do not depend on a choice of the gauge vector. The important role of coherence effects in both space-like and time-like jet evolution is clarified. (orig.)
Continuous-wave spatial quantum correlations of light induced by multiple scattering
DEFF Research Database (Denmark)
Smolka, Stephan; Ott, Johan Raunkjær; Huck, Alexander
2012-01-01
and reflectance. Utilizing frequency-resolved quantum noise measurements, we observe that the strength of the spatial quantum correlation function can be controlled by changing the quantum state of an incident bright squeezed-light source. Our results are found to be in excellent agreement with the developed......We present theoretical and experimental results on spatial quantum correlations induced by multiple scattering of nonclassical light. A continuous-mode quantum theory is derived that enables determining the spatial quantum correlation function from the fluctuations of the total transmittance...... theory and form a basis for future research on, e. g., quantum interference of multiple quantum states in a multiple scattering medium....
International Nuclear Information System (INIS)
Ma, L.X.; Tan, J.Y.; Zhao, J.M.; Wang, F.Q.; Wang, C.A.
2017-01-01
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. - Highlights: • The Muller matrix of randomly distributed, densely packed spheres are investigated. • The effects of multiple scattering and dependent scattering are analyzed. • The accuracy of radiative transfer theory for densely packed spheres is discussed. • Dependent scattering correction takes effect at medium size parameter or smaller. • Performance of dependent scattering correction
Scaling laws governing the multiple scattering of diatomic molecules under Coulomb explosion
International Nuclear Information System (INIS)
Sigmund, P.
1992-01-01
The trajectories of fast molecules during and after penetration through foils are governed by Coulomb explosion and distorted by multiple scattering and other penetration phenomena. A scattering event may cause the energy available for Coulomb explosion to increase or decrease, and angular momentum may be transferred to the molecule. Because of continuing Coulomb explosion inside and outside the target foil, the transmission pattern recorded at a detector far away from the target is not just a linear superposition of Coulomb explosion and multiple scattering. The velocity distribution of an initially monochromatic and well-collimated, but randomly oriented, beam of molecular ions is governed by a generalization of the standard Bothe-Landau integral that governs the multiple scattering of atomic ions. Emphasis has been laid on the distribution in relative velocity and, in particular, relative energy. The statistical distributions governing the longitudinal motion (i.e., the relative motion along the molecular axis) and the rotational motion can be scaled into standard multiple-scattering distributions of atomic ions. The two scaling laws are very different. For thin target foils, the significance of rotational energy transfer is enhanced by an order of magnitude compared to switched-off Coulomb explosion. A distribution for the total relative energy (i.e., longitudinal plus rotational motion) has also been found, but its scaling behavior is more complex. Explicit examples given for all three distributions refer to power-law scattering. As a first approximation, scattering events undergone by the two atoms in the molecule were assumed uncorrelated. A separate section has been devoted to an estimate of the effect of impact-parameter correlation on the multiple scattering of penetrating molecules
Broadband electromagnetic dipole scattering by coupled multiple nanospheres
Jing, Xufeng; Ye, Qiufeng; Hong, Zhi; Zhu, Dongshuo; Shi, Guohua
2017-11-01
With the development of nanotechnology, the ability to manipulate light at the nanoscale is critical to future optical functional devices. The use of high refractive index dielectric single silicon nanoparticle can achieve electromagnetic dipole resonant properties. Compared with single nanosphere, the use of dimer and trimer introduces an additional dimension (gap size) for improving the performance of dielectric optical devices through the coupling between closely connected silicon nanospheres. When changing the gap size between the nanospheres, the interaction between the particles can be from weak to strong. Compared with single nanospheres, dimerized or trimeric nanospheres exhibit more pronounced broadband scattering properties. In addition, by introducing more complex interaction, the trimericed silicon nanospheres exhibit a more significant increase in bandwidth than expected. In addition, the presence of the substrate will also contribute to the increase in the bandwidth of the nanospheres. The broadband response in dielectric nanostructures can be effectively applied to broadband applications such as dielectric nanoantennas or solar cells.
Zhao, Yaqin; Zhong, Xin; Wu, Di; Zhang, Ye; Ren, Guanghui; Wu, Zhilu
2013-09-01
Optical code-division multiple access (OCDMA) systems usually allocate orthogonal or quasi-orthogonal codes to the active users. When transmitting through atmospheric scattering channel, the coding pulses are broadened and the orthogonality of the codes is worsened. In truly asynchronous case, namely both the chips and the bits are asynchronous among each active user, the pulse broadening affects the system performance a lot. In this paper, we evaluate the performance of a 2D asynchronous hard-limiting wireless OCDMA system through atmospheric scattering channel. The probability density function of multiple access interference in truly asynchronous case is given. The bit error rate decreases as the ratio of the chip period to the root mean square delay spread increases and the channel limits the bit rate to different levels when the chip period varies.
Application of the 2-D discrete-ordinates method to multiple scattering of laser radiation
International Nuclear Information System (INIS)
Zardecki, A.; Gerstl, S.A.W.; Embury, J.F.
1983-01-01
The discrete-ordinates finite-element radiation transport code twotran is applied to describe the multiple scattering of a laser beam from a reflecting target. For a model scenario involving a 99% relative humidity rural aerosol we compute the average intensity of the scattered radiation and correction factors to the Beer-Lambert law arising from multiple scattering. As our results indicate, 2-D x-y and r-z geometry modeling can reliably describe a realistic 3-D scenario. Specific results are presented for the two visual ranges of 1.52 and 0.76 km which show that, for sufficiently high aerosol concentrations (e.g., equivalent to V = 0.76 km), the target signature in a distant detector becomes dominated by multiply scattered radiation from interactions of the laser light with the aerosol environment. The merits of the scaling group and the delta-M approximation for the transfer equation are also explored
Multiple scattering formulation of two-dimensional acoustic and electromagnetic metamaterials
Energy Technology Data Exchange (ETDEWEB)
Torrent, Daniel; Sanchez-Dehesa, Jose, E-mail: datorma1@upvnet.upv.es, E-mail: jsdehesa@upvnet.upv.es [Grupo de Fenomenos Ondulatorios, Departamento de IngenierIa Electronica, Universitat Politecnica de Valencia, Camino de Vera s/n (Edificio 7F), ES-46022 Valencia (Spain)
2011-09-15
A multiple scattering formulation of two-dimensional (2D) acoustic metamaterials is presented. This approach is comprehensive and can lead to frequency-dependent effective parameters (scalar bulk modulus and tensorial mass density), as it is possible to have not only positive or negative ellipsoidal refractive index, but also positive or negative hyperbolic refractive index. The correction due to multiple scattering interactions is included in the theory and it is demonstrated that its contribution is important only for lattices with high filling fractions. Since the surface fields on the scatterers are mainly responsible for the anomalous behavior of the resulting effective medium, complex scatterers can be used to engineer the frequency response. Anisotropic effects are also discussed within this formulation and some numerical examples are reported. A homogenization theory is also extended to electromagnetic wave propagation in 2D lattices of dielectric structures, where Mie resonances are found to be responsible for the metamaterial behavior.
Multiple scattering expansion of the self-energy at finite temperature
International Nuclear Information System (INIS)
Jeon, S.; Ellis, P.J.
1998-01-01
An often used rule that the thermal correction to the self-energy is the thermal phase-space times the forward scattering amplitude from target particles is shown to be the leading term in an exact multiple scattering expansion. Starting from imaginary-time finite-temperature field theory, a rigorous expansion for the retarded self-energy is derived. The relationship to the thermodynamic potential is briefly discussed. copyright 1998 The American Physical Society
Multiple Scattering Expansion of the Self-Energy at Finite Temperature
Jeon, Sangyong; Ellis, Paul J.
1998-01-01
An often used rule that the thermal correction to the self-energy is the thermal phase-space times the forward scattering amplitude from target particles is shown to be the leading term in an exact multiple scattering expansion. Starting from imaginary-time finite-temperature field theory, a rigorous expansion for the retarded self-energy is derived. The relationship to the thermodynamic potential is briefly discussed.
International Nuclear Information System (INIS)
Bret, Boris P. J.; Ferreira, Flavio P.; Nunes-Pereira, Eduardo J.; Belsley, Michael
2010-01-01
We report the decomposition of the enhanced backscattering cone into its constitutive interference fringes. These fringes are due to the constructive interference between reciprocal paths of any multiply scattered wave after ensemble averaging. An optical setup combining a two-point continuous-wave illumination and matching detection allows the observation of the fringes and, therefore, the quantitative characterization of the Green's function for light propagation between the two points in a multiple-scattering media.
Analytical calculations of multiple scattering for high energy photons and neutrons
International Nuclear Information System (INIS)
Thoe, R.S.
1994-04-01
Radiography of large dense objects often require the use of highly penetrating radiation. For example, a couple of centimeters of steel attenuates 50 keV x-rays by a factor of approximately 10 -14 whereas this same amount of steel would attenuate a 500 keV photon beam by only a factor of about 0.25. However, this increase in penetrating power comes with a price. In the case of x-radiation there are two bills to pay: (1) For projection radiography, this increase in penetration directly causes a corresponding decrease in resolution. (2) This increase in penetration occurs in a region where the interaction of radiation and matter is changing from absorption to scattering. In the above example the fraction of scattering goes from about 0.1 at 50 keV to over 0.99 at 500 keV. These scattered photons can significantly degrade contrast. In order to overcome some of these difficulties, radiography using scattered photons has been studied by myself and numerous other authors. In all the above cases, calculation of the intensity of scattered radiation is of primary importance. In cases where scattering is probable, multiple scattering can also be probable. Calculations of multiple scattering are generally very difficult and usually require the use of extremely sophisticated Monte Carlo simulations. It is not unusual for these calculations to require several hours of CPU time on some of the worlds largest and fastest supercomputers. In this paper I will present an alternative approach. I will present an analytical solution to the equations of double scattering, and show how this solution can extended to the case of higher order scattering. Finally, I will give numerical examples of these solutions and compare them to solutions obtained by Monte Carlo simulations
Multiple scattering of electromagnetic waves by a collection of plasma drift turbulent vortices
International Nuclear Information System (INIS)
Resendes, D.
1995-01-01
An application of the self-consistent multiple-scattering theory of electro-magnetic waves to drift turbulent vortices is presented. Using the known single-vortex solution, the integral equation describing the scattering from a finite density of drift turbulent vortices is obtained. Rather than solving this equation and then averaging, the averaging operation is taken first to obtain statistical moment equations, from which the coherent and incoherent scattering follow. These results are expressed in a Fourier basis, and the cross-section is evaluated. Limiting forms of the theory and straightforward generalizations are discussed. (Author)
Lambert, Simon A.; Näsholm, Sven Peter; Nordsletten, David; Michler, Christian; Juge, Lauriane; Serfaty, Jean-Michel; Bilston, Lynne; Guzina, Bojan; Holm, Sverre; Sinkus, Ralph
2015-08-01
Wave scattering provides profound insight into the structure of matter. Typically, the ability to sense microstructure is determined by the ratio of scatterer size to probing wavelength. Here, we address the question of whether macroscopic waves can report back the presence and distribution of microscopic scatterers despite several orders of magnitude difference in scale between wavelength and scatterer size. In our analysis, monosized hard scatterers 5 μ m in radius are immersed in lossless gelatin phantoms to investigate the effect of multiple reflections on the propagation of shear waves with millimeter wavelength. Steady-state monochromatic waves are imaged in situ via magnetic resonance imaging, enabling quantification of the phase velocity at a voxel size big enough to contain thousands of individual scatterers, but small enough to resolve the wavelength. We show in theory, experiments, and simulations that the resulting coherent superposition of multiple reflections gives rise to power-law dispersion at the macroscopic scale if the scatterer distribution exhibits apparent fractality over an effective length scale that is comparable to the probing wavelength. Since apparent fractality is naturally present in any random medium, microstructure can thereby leave its fingerprint on the macroscopically quantifiable power-law exponent. Our results are generic to wave phenomena and carry great potential for sensing microstructure that exhibits intrinsic fractality, such as, for instance, vasculature.
Liu, Xiaodong
2017-08-01
A sampling method by using scattering amplitude is proposed for shape and location reconstruction in inverse acoustic scattering problems. Only matrix multiplication is involved in the computation, thus the novel sampling method is very easy and simple to implement. With the help of the factorization of the far field operator, we establish an inf-criterion for characterization of underlying scatterers. This result is then used to give a lower bound of the proposed indicator functional for sampling points inside the scatterers. While for the sampling points outside the scatterers, we show that the indicator functional decays like the bessel functions as the sampling point goes away from the boundary of the scatterers. We also show that the proposed indicator functional continuously depends on the scattering amplitude, this further implies that the novel sampling method is extremely stable with respect to errors in the data. Different to the classical sampling method such as the linear sampling method or the factorization method, from the numerical point of view, the novel indicator takes its maximum near the boundary of the underlying target and decays like the bessel functions as the sampling points go away from the boundary. The numerical simulations also show that the proposed sampling method can deal with multiple multiscale case, even the different components are close to each other.
Two-dimensional phononic crystals with time-varying properties: a multiple scattering analysis
International Nuclear Information System (INIS)
Wright, D W; Cobbold, R S C
2010-01-01
Multiple scattering theory is a versatile two- and three-dimensional method for characterizing the acoustic wave transmission through many scatterers. It provides analytical solutions to wave propagation in scattering structures, and its computational complexity grows logarithmically with the number of scatterers. In this paper we show how the 2D method can be adapted to include the effects of time-varying material parameters. Specifically, a new T-matrix is defined to include the effects of frequency modulation that occurs in time-varying phononic crystals. Solutions were verified against finite difference time domain (FDTD) simulations and showed excellent agreement. This new method enables fast characterization of time-varying phononic crystals without the need to resort to lengthy FDTD simulations. Also, the method of combining T-matrices to form the T-supermatrix remains unchanged provided that the new matrix definitions are used. The method is quite compatible with existing implementations of multiple scattering theory and could be readily extended to three-dimensional multiple scattering theory
MULTIPLE-PLANET SCATTERING AND THE ORIGIN OF HOT JUPITERS
International Nuclear Information System (INIS)
Beaugé, C.; Nesvorný, D.
2012-01-01
Doppler and transit observations of exoplanets show a pile-up of Jupiter-size planets in orbits with a 3 day period. A fraction of these hot Jupiters have retrograde orbits with respect to the parent star's rotation, as evidenced by the measurements of the Rossiter-McLaughlin effect. To explain these observations we performed a series of numerical integrations of planet scattering followed by the tidal circularization and migration of planets that evolved into highly eccentric orbits. We considered planetary systems having three and four planets initially placed in successive mean-motion resonances, although the angles were taken randomly to ensure orbital instability in short timescales. The simulations included the tidal and relativistic effects, and precession due to stellar oblateness. Our results show the formation of two distinct populations of hot Jupiters. The inner population (Population I) is characterized by semimajor axis a 1 Gyr and fits nicely the observed 3 day pile-up. A comparison between our three-planet and four-planet runs shows that the formation of hot Jupiters is more likely in systems with more initial planets. Due to the large-scale chaoticity that dominates the evolution, high eccentricities and/or high inclinations are generated mainly by close encounters between the planets and not by secular perturbations (Kozai or otherwise). The relative proportion of retrograde planets seems of be dependent on the stellar age. Both the distribution of almost aligned systems and the simulated 3 day pile-up also fit observations better in our four-planet simulations. This may suggest that the planetary systems with observed hot Jupiters were originally rich in the number of planets, some of which were ejected. In a broad perspective, our work therefore hints on an unexpected link between the hot Jupiters and recently discovered free floating planets.
Point spread function due to multiple scattering of light in the atmosphere
International Nuclear Information System (INIS)
Pękala, J.; Wilczyński, H.
2013-01-01
The atmospheric scattering of light has a significant influence on the results of optical observations of air showers. It causes attenuation of direct light from the shower, but also contributes a delayed signal to the observed light. The scattering of light therefore should be accounted for, both in simulations of air shower detection and reconstruction of observed events. In this work a Monte Carlo simulation of multiple scattering of light has been used to determine the contribution of the scattered light in observations of a point source of light. Results of the simulations and a parameterization of the angular distribution of the scattered light contribution to the observed signal (the point spread function) are presented. -- Author-Highlights: •Analysis of atmospheric scattering of light from an isotropic point source. •Different geometries and atmospheric conditions were investigated. •A parameterization of scattered light distribution has been developed. •The parameterization allows one to easily account for the light scattering in air. •The results will be useful in analyses of observations of extensive air shower
Development of multiple scattering lidar to retrieve cloud extinction and size information
International Nuclear Information System (INIS)
Kim, Dukhyeon; Cheong, Hai Du; Kim, Young Gi; Park, Sun Ho
2008-01-01
Traditional Mie scattering cloud lidar have some limitations because of multiple scattering effects. Because this multiple scattering effects induce depolarization of spherical particle and enhancement of extinction coefficient. We cannot measure the phase of water with depolarization lidar, and also cannot measure the extinction coefficient with single FOV(Field Of View)Mie cloud lidar system. In the study, we have developed a multiple field of view Mie cloud liar system which can give many information about the cloud droplet such as cloud effective size, cloud number density, extinction coefficient of cloud, and phase of water through the correction of multiple scattering effects. For this purpose, we have developed a multiple field of view lidar system which composed of 32 different pinholes. Figure 1 shows the schematic diagram and picture of pinholes which start from 100μm to 8mm. Pihole is located at the focal plane of the parabolic mirror, in this case the minimum FOV is 67μrad, maximum FOV is 5.3 mrad. Figure 2 shows Monte Carlo simulation of the multiple scattering photons vs. cloud depth. In this calculation we assumed that wavelength normalized aerosol size(x)is 100, and density of cloud (extinction efficiency)is 0.01m"-1". By measuring FOV dependent signals and aerosol extinction coefficient we can extract effective droplet size through following equations. Here θ"d"is aerosol effective size, and z"j", f, Θ(z)are height, aerosol density dependent function, and angular size of lidar signal at the height z. Finally. f(z)depends on the light mean free path and number of scattering
Analysis of the factors that affect photon counts in Compton scattering
International Nuclear Information System (INIS)
Luo, Guang; Xiao, Guangyu
2015-01-01
Compton scattering has been applied in a variety of fields. The factors that affect Compton scattering have been studied extensively in the literature. However, the factors that affect the measured photon counts in Compton scattering are rarely considered. In this paper, we make a detailed discussion on those factors. First, Compton scattering experiments of some alloy series and powder mixture series are explored. Second, the electron density is researched in terms of atom and lattice constants. Third, the factor of attenuation coefficient is discussed. And then, the active degree of electrons is discussed based on the DFT theory. Lastly, the conclusions are made, that the factors affecting Compton scattering photon counts include mainly electron number density, attenuation coefficient and active degree of electrons. - Highlights: • Compton scattering experiments of some alloy series and powder mixture series are explored. • The influence of electron density is researched in terms of atom and lattice constants. • The influence of attenuation coefficient is discussed. • The active degree of electrons is discussed detailedly based on DFT theory
International Nuclear Information System (INIS)
Arneodo, M.; Ferrero, M.I.; Peroni, C.; Bee, C.P.; Bird, I.; Coughlan, J.; Sloan, T.; Braun, H.; Brueck, H.; Drees, J.; Edwards, A.; Krueger, J.; Montgomery, H.E.; Peschel, H.; Pietrzyk, U.; Poetsch, M.; Schneider, A.; Dreyer, T.; Ernst, T.; Haas, J.; Kabuss, E.M.; Landgraf, U.; Mohr, W.; Rith, K.; Schlagboehmer, A.; Schroeder, T.; Stier, H.E.; Wallucks, W.
1987-01-01
The multiplicity distributions of charged hadrons produced in the deep inelastic muon-proton scattering at 280 GeV are analysed in various rapidity intervals, as a function of the total hadronic centre of mass energy W ranging from 4-20 GeV. Multiplicity distributions for the backward and forward hemispheres are also analysed separately. The data can be well parameterized by binomial distributions, extending their range of applicability to the case of lepton-proton scattering. The energy and the rapidity dependence of the parameters is presented and a smooth transition from the binomial distribution via Poissonian to the ordinary binomial is observed. (orig.)
Rakotonarivo, S T; Walker, S C; Kuperman, W A; Roux, P
2011-12-01
A method to actively localize a small perturbation in a multiple scattering medium using a collection of remote acoustic sensors is presented. The approach requires only minimal modeling and no knowledge of the scatterer distribution and properties of the scattering medium and the perturbation. The medium is ensonified before and after a perturbation is introduced. The coherent difference between the measured signals then reveals all field components that have interacted with the perturbation. A simple single scatter filter (that ignores the presence of the medium scatterers) is matched to the earliest change of the coherent difference to localize the perturbation. Using a multi-source/receiver laboratory setup in air, the technique has been successfully tested with experimental data at frequencies varying from 30 to 60 kHz (wavelength ranging from 0.5 to 1 cm) for cm-scale scatterers in a scattering medium with a size two to five times bigger than its transport mean free path. © 2011 Acoustical Society of America
A Two-Dimensional Helmholtz Equation Solution for the Multiple Cavity Scattering Problem
2013-02-01
obtained by using the block Gauss – Seidel iterative meth- od. To show the convergence of the iterative method, we define the error between two...models to the general multiple cavity setting. Numerical examples indicate that the convergence of the Gauss – Seidel iterative method depends on the...variational approach. A block Gauss – Seidel iterative method is introduced to solve the cou- pled system of the multiple cavity scattering problem, where
Multiplicities of charged kaons from deep-inelastic muon scattering off an isoscalar target
Czech Academy of Sciences Publication Activity Database
Adolph, C.; Aghasyan, M.; Akhunzyanov, R.; Alexeev, M. G.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Anfimov, N. V.; Anosov, V.; Augsten, K.; Augustyniak, W.; Austregesilo, A.; Azevedo, C.; Badelek, B.; Balestra, F.; Ball, M.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E. R.; Birsa, R.; Bodlák, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Büchele, M.; Capozza, L.; Chang, W.-C.; Chatterjee, C.; Chiosso, M.; Choi, A.; Chung, S. U.; Cicuttin, A.; Crespo, M.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O.; Dhara, L.; Donskov, S. V.; Doshita, N.; Dreisbach, Ch.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Eversheim, P.D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; Finger jr., M.; Fischer, H.; Franco, C.; Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmüller, S.; Grasso, A.; Grosse-Perdekapm, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; Hamar, G.; von Harrach, D.; Heinsius, F. H.; Heitz, R.; Herrmann, F.; Horikawa, N.; d'Hose, N.; Hsieh, C.-Yu.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jarý, V.; Joosten, R.; Jörg, P.; Kabuss, E.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Y.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O.; Krämer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z. V.; Kulinich, Y.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lian, Y.-S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G.; Marianski, B.; Martin, A.; Marzec, J.; Matoušek, R.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, M.; Meyer, W.; Mikhailov, Yu. V.; Mikhasenko, M.; Mitrofanov, E.; Mitrofanov, N.; Miyachi, Y.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nový, J.; Nowak, W. D.; Nukazuka, G.; Nunes, A.S.; Olshevsky, A. G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.-C.; Pereira, F.; Pešek, M.; Peshekhonov, D. V.; Pierre, N.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Roskot, M.; Rossiyskaya, N. S.; Ryabchikov, D.; Rybnikov, A.; Rychter, A.; Salač, R.; Samoylenko, V. D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I. A.; Sawada, H.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schönning, K.; Seder, E.; Selyunin, A.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Smolík, J.; Sozzi, F.; Srnka, Aleš; Steffen, D.; Stolarski, M.; Subrt, O.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Tasevsky, M.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Thiel, A.; Tosello, F.; Tskhay, V.; Uhl, S.; Veloso, J.; Virius, M.; Vondra, J.; Wallner, S.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Ter Wolbeek, J.; Zaremba, K.; Závada, P.; Zavertyaev, M.; Zemlyanichkina, E.; Zhuravlev, N.; Ziembicki, M.; Zink, A.
2017-01-01
Roč. 767, 10 APRIL (2017), s. 133-141 ISSN 0370-2693 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : deep inelastic scattering * kaon multiplicities * quark fragmentation functions * strange quark Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Nuclear physics Impact factor: 4.807, year: 2016
Coulomb correction to the screening angle of the Moliere multiple scattering theory
International Nuclear Information System (INIS)
Kuraev, E.A.; Voskresenskaya, O.O.; Tarasov, A.V.
2012-01-01
Coulomb correction to the screening angular parameter of the Moliere multiple scattering theory is found. Numerical calculations are presented in the range of nuclear charge 4 ≤ Z ≤ 82. Comparison with the Moliere result for the screening angle reveals up to 30% deviation from it for sufficiently heavy elements of the target material
Multiple scattering in electron fluid and energy loss in multi-ionic targets
Energy Technology Data Exchange (ETDEWEB)
Deutsch, C., E-mail: claude.deutsch@u-psud.fr [LPGP, UParis-Sud, 91405-Orsay (France); Tahir, N.A. [GSI, 1Planck Str., 64291-Darmstadt (Germany); Barriga-Carrasco, M. [ETSII, UCastilla-la-Mancha, 13071 Ciudad-Real (Spain); Ceban, V. [LPGP, UParis-Sud, 91405-Orsay (France); Fromy, P. [CRI, UParis-Sud, 91405-Orsay (France); Gilles, D. [CEA/Saclay/DSM/IRFU/SAP, 91191-Gif-s-Yvette (France); Leger, D. [Laboratoire Monthouy, UValenciennes-Hainaut Cambresis (France); Maynard, G. [LPGP, UParis-Sud, 91405-Orsay (France); Tashev, B. [Department of Physics, KazNu, Tole Bi82, Almaty (Kazakhstan); Volpe, L. [Department of Physics, UMilano-Bicocca, Milano 20126 (Italy)
2014-01-01
Extensions of the standard stopping model (SSM) for ion projectiles interacting with dense targets of timely concern for ICF and WDM are reviewed. They include multiple scattering on partially degenerate electrons, low velocity ion slowing down in demixing H–He mixtures within Jovian planets core or multiionic target such as Kapton.
Multiple scattering in electron fluid and energy loss in multi-ionic targets
International Nuclear Information System (INIS)
Deutsch, C.; Tahir, N.A.; Barriga-Carrasco, M.; Ceban, V.; Fromy, P.; Gilles, D.; Leger, D.; Maynard, G.; Tashev, B.; Volpe, L.
2014-01-01
Extensions of the standard stopping model (SSM) for ion projectiles interacting with dense targets of timely concern for ICF and WDM are reviewed. They include multiple scattering on partially degenerate electrons, low velocity ion slowing down in demixing H–He mixtures within Jovian planets core or multiionic target such as Kapton
A method for the generation of random multiple Coulomb scattering angles
International Nuclear Information System (INIS)
Campbell, J.R.
1995-06-01
A method for the random generation of spatial angles drawn from non-Gaussian multiple Coulomb scattering distributions is presented. The method employs direct numerical inversion of cumulative probability distributions computed from the universal non-Gaussian angular distributions of Marion and Zimmerman. (author). 12 refs., 3 figs
MCRTOF, Multiple Scattering of Resonance Region Neutron in Time of Flight Experiments
International Nuclear Information System (INIS)
Ohkubo, Mako
1984-01-01
1 - Description of program or function: Multiple scattering of neutrons in the resonance energy region impinging on a disk with an arbitrary angle. 2 - Method of solution: The Monte Carlo method is employed to simulate the path of an incident neutron in a medium for which macroscopic cross sections are determined by resonance parameters. By tracing a large number of neutrons, probabilities for capture, transmission, front-face scattering, rear-face scattering and side-face scattering are determined and printed out as function of incident neutron energy. Optionally, the distribution of capture locations in the disk can be printed. The incident neutron energy is swept to fit a situation as encountered in time-of-flight experiments. 3 - Restrictions on the complexity of the problem: The cross section file is constructed from input resonance parameters with a single- level Breit-Wigner formula. The following restrictions and simplifications apply: - The maximum number of resonances is five. - Reactions other than capture and scattering are neglected. - The angular scattering distribution in the center-of-mass system is assumed to be uniform. - Chemical binding effects are neglected
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...
A multiple scattering theory for EM wave propagation in a dense random medium
Karam, M. A.; Fung, A. K.; Wong, K. W.
1985-01-01
For a dense medium of randomly distributed scatterers an integral formulation for the total coherent field has been developed. This formulation accounts for the multiple scattering of electromagnetic waves including both the twoand three-particle terms. It is shown that under the Markovian assumption the total coherent field and the effective field have the same effective wave number. As an illustration of this theory, the effective wave number and the extinction coefficient are derived in terms of the polarizability tensor and the pair distribution function for randomly distributed small spherical scatterers. It is found that the contribution of the three-particle term increases with the particle size, the volume fraction, the frequency and the permittivity of the particle. This increase is more significant with frequency and particle size than with other parameters.
Factors affecting dignity of patients with multiple sclerosis.
Sharifi, Simin; Borhani, Fariba; Abbaszadeh, Abbas
2016-12-01
MS is one of the most common chronic diseases of the nervous system. Apart from disease progression, other complications such as unemployment, separation and divorce could potentially threat patients' dignity. Most of the previous studies have been done of maintaining patients' dignity in interaction with healthcare team, but studies on affecting factors of dignity in chronic patients in the society and in interaction with usual people are scarce. We aimed to investigate factors affecting dignity of Iranian patients with MS in daily living and in interaction of them with the society. In this qualitative study, 13 patients with multiple sclerosis were chosen by purposive sampling and semi-structured interviews were conducted until data saturation. The study was done in Tehran, the capital city of Iran. Factors affecting dignity were classified as 'personal factors' and 'social factors'. Personal factors consist of the following subcategories: patients' communication with self, patients' knowledge, patients' values and beliefs and patients' resources. Social factors include others' communication with patients, social knowledge, social values and beliefs and social resources. Multiple personal and social factors interfere in perceived patient dignity. In fact, interaction between personal and social factors can be influential in final perceived dignity. By focusing on whole aspects of the patients' lives, we can identify dignity-promoting or dignity-threatening factors and help patients maintain their dignity by taking appropriate measures for moderating threatening factors and improving dignity enhancing ones. © 2016 Nordic College of Caring Science.
Pinheiro, F A; Martínez, A S
2001-01-01
We review some of our recent results concerning the single and multiple electromagnetic scattering by magnetic spherical particles. For a single electromagnetic scattering we show that the magnetic contribution alters, when compared to nonmagnetic scattering, the behavior of the cross sections and mean cosine of the scattering angle (cos omega). For ferromagnetic particles, resonances may occur even in the small-particle limit when the particle radius is much smaller than the wavelength. The resonances increase the cross sections while (cos omega) is diminished , and even may become negative. Several quantities such the Ioffe-Regel parameter for localization are calculated for the multiple scattering regime. We show that magnetic scattering favors the observation of localization of electromagnetic waves in three dimensions. Further, this is also verified for dynamical experiments, where we show that the diffusion constant can be very small. Since the magnetic permeability of the scatterers can vary significan...
International Nuclear Information System (INIS)
Singh, Gurvinderjit; Singh, Manpreet; Sandhu, B.S.; Singh, Bhajan
2008-01-01
The energy, intensity and angular distributions of multiple scattering of 662 keV gamma photons, emerging from targets of pure elements and binary alloys, are observed as a function of target thickness in reflection and transmission geometries. The observed spectra recorded by a properly shielded NaI (Tl) scintillation detector, in addition to singly scattered events, consist of photons scattered more than once for thick targets. To extract the contribution of multiply scattered photons from the measured spectra, a singly scattered distribution is reconstructed analytically. We observe that the numbers of multiply scattered events increase with increase in target thickness, and saturate for a particular thickness called saturation thickness. The saturation thickness decreases with increasing atomic number. The multiple scattering, an interfering background noise in Compton profiles and Compton cross-section measurements, has been successfully used as a new technique to assign the 'effective atomic number' to binary alloys. Monte Carlo calculations support the present experimental results
Multiple scattering of low energy rare gas ions: a comparison of experiment and computer simulation
International Nuclear Information System (INIS)
Heiland, W.; Taglauer, E.; Robinson, M.T.
1976-01-01
Some aspects of ion scattering below a few keV have been interpreted by multiple scattering. This can partly be simulated by chain or string models, where the single crystal surface is replaced by a chain of atoms. The computer program MARLOWE allows a simulation of solid-ion interaction, which is much closer to reality, e.g. the crystal is three-dimensional, includes lattice vibrations, electronic stopping power, different scattering potentials, etc. It is shown that the energy of the reflected ions as a function of the primary energy, lattice constant, impact angle and scattering angle can be understood within the string model. These results of the string model are confirmed by the MARLOWE calculations. For an interpretation of the measured intensities the simple string model is insufficient, whereas with MARLOWE reasonable agreement with experimental data may be achieved, if the thermal vibrations of the lattice atoms are taken into account. The experimental data include Ne + →Ni, Ne + →Ag and preliminary data on Ne + →W. The screening parameters of the scattering potentials are estimated for these ion-atom combinations. The results allow some conclusions about surface Debye temperatures. (Auth.)
Kuo, C. P.; Yang, P.; Huang, X.; Feldman, D.; Flanner, M.; Kuo, C.; Mlawer, E. J.
2017-12-01
Clouds, which cover approximately 67% of the globe, serve as one of the major modulators in adjusting radiative energy on the Earth. Since rigorous radiative transfer computations including multiple scattering are costly, only absorption is considered in the longwave spectral bands in the radiation sub-models of the general circulation models (GCMs). Quantification of the effect of ignoring longwave scattering for flux and heating rate simulations is performed by using the GCM version of the Longwave Rapid Radiative Transfer Model (RRTMG_LW) with an implementation with the 16-stream Discrete Ordinates Radiative Transfer (DISORT) Program for a Multi-Layered Plane-Parallel Medium in conjunction with the 2010 CCCM products that merge satellite observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), the CloudSat, the Clouds and the Earth's Radiant Energy System (CERES) and the Moderate Resolution Imaging Spectrometer (MODIS). One-year global simulations show that neglecting longwave scattering overestimates upward flux at the top of the atmosphere (TOA) and underestimates downward flux at the surface by approximately 2.63 and 1.15 W/m2, respectively. Furthermore, when longwave scattering is included in the simulations, the tropopause is cooled by approximately 0.018 K/day and the surface is heated by approximately 0.028 K/day. As a result, the radiative effects of ignoring longwave scattering and doubling CO2 are comparable in magnitude.
International Nuclear Information System (INIS)
Kawrakow, I.; Bielajew, A.F.
1998-01-01
A new representation of elastic electron-nucleus (Coulomb) multiple-scattering distributions is developed. Using the screened Rutherford cross section with the Moliere screening parameter as an example, a simple analytic angular transformation of the Goudsmit-Saunderson multiple-scattering distribution accounts for most of the structure of the angular distribution leaving a residual 3-parameter (path-length, transformed angle and screening parameter) function that is reasonably slowly varying and suitable for rapid, accurate interpolation in a computer-intensive algorithm. The residual function is calculated numerically for a wide range of Moliere screening parameters and path-lengths suitable for use in a general-purpose condensed-history Monte Carlo code. Additionally, techniques are developed that allow the distributions to be scaled to account for energy loss. This new representation allows ''''on-the-fly'''' sampling of Goudsmit-Saunderson angular distributions in a screened Rutherford approximation suitable for class II condensed-history Monte Carlo codes. (orig.)
Smith, James A.
1992-01-01
The inversion of the leaf area index (LAI) canopy parameter from optical spectral reflectance measurements is obtained using a backpropagation artificial neural network trained using input-output pairs generated by a multiple scattering reflectance model. The problem of LAI estimation over sparse canopies (LAI 1000 percent for low LAI. Minimization methods applied to merit functions constructed from differences between measured reflectances and predicted reflectances using multiple-scattering models are unacceptably sensitive to a good initial guess for the desired parameter. In contrast, the neural network reported generally yields absolute percentage errors of <30 percent when weighting coefficients trained on one soil type were applied to predicted canopy reflectance at a different soil background.
Multiplicities of charged kaons from deep-inelastic muon scattering off an isoscalar target
Adolph, C.
2017-04-10
Precise measurements of charged-kaon multiplicities in deep inelastic scattering were performed. The results are presented in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y, and the fraction z of the virtual-photon energy carried by the produced hadron. The data were obtained by the COMPASS Collaboration by scattering 160 GeV muons off an isoscalar 6 LiD target. They cover the kinematic domain 1 (GeV/c)2 5 GeV/c^2 in the invariant mass of the hadronic system. The results from the sum of the z-integrated K+ and K- multiplicities at high x point to a value of the non-strange quark fragmentation function larger than obtained by the earlier DSS fit.
Multiplicities of charged kaons from deep-inelastic muon scattering off an isoscalar target
Directory of Open Access Journals (Sweden)
C. Adolph
2017-04-01
Full Text Available Precise measurements of charged-kaon multiplicities in deep inelastic scattering were performed. The results are presented in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y, and the fraction z of the virtual-photon energy carried by the produced hadron. The data were obtained by the COMPASS Collaboration by scattering 160 GeV muons off an isoscalar 6LiD target. They cover the kinematic domain 1(GeV/c25 GeV/c2 in the invariant mass of the hadronic system. The results from the sum of the z-integrated K+ and K− multiplicities at high x point to a value of the non-strange quark fragmentation function larger than obtained by the earlier DSS fit.
Ben-David, Avishai
1992-01-01
Knowing the optical properties of aerosol dust is important for designing electro-optical systems and for modeling the effect on propagation of light in the atmosphere. As CO2 lidar technology becomes more advanced and is used for multiwavelength measurements, information on the wavelength dependent backscattering of aerosol dust particles is required. The volume backscattering coefficient of aerosols in the IR is relatively small. Thus, only a few field measurements of backscattering, usually at only a few wavelengths, are reported in the literature. We present spectral field measurements of backscattering of kaolin dust in the 9-11 micron wavelength range. As the quantity of dust increases, multiple scattering contributes more to the measured backscattered signal. The measurements show the effect of the dust quantity of the spectral backscatter measurements. A simple analytical two stream radiative transfer model is applied to confirm the measurements and to give insight to the multiple scattering spectra of backscattering.
Electromagnetic imaging of multiple-scattering small objects: non-iterative analytical approach
International Nuclear Information System (INIS)
Chen, X; Zhong, Y
2008-01-01
Multiple signal classification (MUSIC) imaging method and the least squares method are applied to solve the electromagnetic inverse scattering problem of determining the locations and polarization tensors of a collection of small objects embedded in a known background medium. Based on the analysis of induced electric and magnetic dipoles, the proposed MUSIC method is able to deal with some special scenarios, due to the shapes and materials of objects, to which the standard MUSIC doesn't apply. After the locations of objects are obtained, the nonlinear inverse problem of determining the polarization tensors of objects accounting for multiple scattering between objects is solved by a non-iterative analytical approach based on the least squares method
Atmospheric neutrino oscillations from upward throughgoing muon multiple scattering in MACRO
Energy Technology Data Exchange (ETDEWEB)
Ambrosio, M.; Antolini, R.; Bakari, D.; Baldini, A.; Barbarino, G.C.; Barish, B.C.; Battistoni, G.; Becherini, Y.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bloise, C.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Carboni, M.; Caruso, R.; Cecchini, S.; Cei, F.; Chiarella, V.; Chiarusi, T.; Choudhary, B.C.; Coutu, S.; Cozzi, M.; De Cataldo, G.; Dekhissi, H.; De Marzo, C.; De Mitri, I.; Derkaoui, J.; De Vincenzi, M.; Di Credico, A.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Grillo, A.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Iarocci, E.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kumar, A.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D.S.; Lipari, P.; Longo, M.J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Manzoor, S.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M.N.; Michael, D.G.; Mikheyev, S.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolo, D.; Nolty, R.; Orth, C.; Osteria, G.; Palamara, O.; Patera, V.; Patrizii, L.; Pazzi, R.; Peck, C.W.; Perrone, L.; Petrera, S.; Popa, V.; Raino, A.; Reynoldson, J.; Ronga, F.; Rrhioua, A.; Satriano, C.; Scapparone, E.; Scholberg, K.; Sciubba, A.; Serra, P.; Sioli, M.; Sirri, G.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J.L.; Sulak, L.R.; Surdo, A.; Tarle, G.; Togo, V.; Vakili, M.; Walter, C.W.; Webb, R
2003-07-24
The energy of atmospheric neutrinos detected by MACRO was estimated using multiple Coulomb scattering of upward throughgoing muons. This analysis allows a test of atmospheric neutrino oscillations, relying on the distortion of the muon energy distribution. These results have been combined with those coming from the upward throughgoing muon angular distribution only. Both analyses are independent of the neutrino flux normalization and provide strong evidence, above the 4{sigma} level, in favour of neutrino oscillations.
All orders Boltzmann collision term from the multiple scattering expansion of the self-energy
International Nuclear Information System (INIS)
Fillion-Gourdeau, F.; Gagnon, J.-S.; Jeon, S.
2007-01-01
We summarize our main findings in deriving the Boltzmann collision term from the Kadanoff-Baym relativistic transport equation and the multiple scattering expansion of the self-energy within a quasi-particle approximation. Our collision term is valid to all orders in perturbation theory and contains processes with any number of participating particles. This work completes a program initiated by Carrington and Mrowczynski and developed further by present authors and Weinstock in recent literature
Exploitation of Microdoppler and Multiple Scattering Phenomena for Radar Target Recognition
2006-08-24
progress on the reserach grant "Exploitation of MicroDoppler and Multiple Scattering Phenomena for Radar Target Recognition" during the period 1...paper describes a methodology of modeling A number of ray-based EM techniques have been interferometric synthetic aperture radar (IFSAR) images...modes including the single present an IFSAR simulation methodology to simulate the antenna transmit mode, the ping-pong mode or the repeat interferogram
Quantum theory of dynamic multiple light scattering in fluctuating disordered media
International Nuclear Information System (INIS)
Skipetrov, S. E.
2007-01-01
We formulate a quantum theory of dynamic multiple light scattering in fluctuating disordered media and calculate the fluctuation and the autocorrelation function of the photon number operator for light transmitted through a disordered slab. The effect of disorder on the information capacity of a quantum communication channel operating in a disordered environment is estimated, and the use of squeezed light in diffusing-wave spectroscopy is discussed
International Nuclear Information System (INIS)
Broome, J.
1965-11-01
The programme SCATTER is a KDF9 programme in the Egtran dialect of Fortran to generate normalized angular distributions for elastically scattered neutrons from data input as the coefficients of a Legendre polynomial series, or from differential cross-section data. Also, differential cross-section data may be analysed to produce Legendre polynomial coefficients. Output on cards punched in the format of the U.K. A. E. A. Nuclear Data Library is optional. (author)
Multiple scattering theory and applications for intermediate energy reactions of nuclei
International Nuclear Information System (INIS)
Ludeking, L.D.
1979-01-01
Interactions of two composite clusters are treated in a multiple scattering framework whereby many-particle operators are decomposed into a systematic and finite series such that there is an ordered sequestering according to particle rank. Thus, an N-body operator is written as the superposition of all distinct groupings of interactions that occur between particle pairs, triplets, quartets, etc., such that all groupings contain at least one particle from each of the composite systems. It is demonstrated how the transition operator, a reaction operator, and an optical potential may be described in this context. The general structure of such decompositions is shown, and the connection to the standard multiple-scattering prescriptions, delineated. The direct reaction amplitude for stripping and pickup is described, and the two potential formula of Gell-Mann and Goldberger is derived. The multiple scattering formalism for direct reactions is constructed in the eikonal approximation. The sensitivity of the transition cross section to the target density and nucleon-nucleon density correlations are examined in this framework. The limitations of the zero-range approximation to the deuteron vertex function are examined by comparison with the finite-range vertex function at a range of energies. 25 figures, 5 tables
Directory of Open Access Journals (Sweden)
Wasaye Muhammad Abdul
2017-01-01
Full Text Available An algorithm for the Monte Carlo simulation of electron multiple elastic scattering based on the framework of SuperMC (Super Monte Carlo simulation program for nuclear and radiation process is presented. This paper describes efficient and accurate methods by which the multiple scattering angular deflections are sampled. The Goudsmit-Saunderson theory of multiple scattering has been used for sampling angular deflections. Differential cross-sections of electrons and positrons by neutral atoms have been calculated by using Dirac partial wave program ELSEPA. The Legendre coefficients are accurately computed by using the Gauss-Legendre integration method. Finally, a novel hybrid method for sampling angular distribution has been developed. The model uses efficient rejection sampling method for low energy electrons (500 mean free paths. For small path lengths, a simple, efficient and accurate analytical distribution function has been proposed. The later uses adjustable parameters determined from the fitting of Goudsmith-Saunderson angular distribution. A discussion of the sampling efficiency and accuracy of this newly developed algorithm is given. The efficiency of rejection sampling algorithm is at least 50 % for electron kinetic energies less than 500 keV and longer path lengths (>500 mean free paths. Monte Carlo Simulation results are then compared with measured angular distributions of Ross et al. The comparison shows that our results are in good agreement with experimental measurements.
Correlations in multiple production on nuclei and Glauber model of multiple scattering
International Nuclear Information System (INIS)
Zoller, V.R.; Nikolaev, N.N.
1982-01-01
Critical analysis of possibility for describing correlation phenomena during multiple production on nuclei within the framework of the Glauber multiple seattering model generalized for particle production processes with Capella, Krziwinski and Shabelsky has been performed. It was mainly concluded that the suggested generalization of the Glauber model gives dependences on Ng(Np) (where Ng-the number of ''grey'' tracess, and Np-the number of protons flying out of nucleus) and, eventually, on #betta# (where #betta#-the number of intranuclear interactions) contradicting experience. Independent of choice of relation between #betta# and Ng(Np) in the model the rapidity corrletor Rsub(eta) is overstated in the central region and understated in the region of nucleus fragmentation. In mean multiplicities these two contradictions of experience are disguised with random compensation and agreement with experience in Nsub(S) (function of Ng) cannot be an argument in favour of the model. It is concluded that eiconal model doesn't permit to quantitatively describe correlation phenomena during the multiple production on nuclei
Dual wavelength multiple-angle light scattering system for cryptosporidium detection
Buaprathoom, S.; Pedley, S.; Sweeney, S. J.
2012-06-01
A simple, dual wavelength, multiple-angle, light scattering system has been developed for detecting cryptosporidium suspended in water. Cryptosporidium is a coccidial protozoan parasite causing cryptosporidiosis; a diarrheal disease of varying severity. The parasite is transmitted by ingestion of contaminated water, particularly drinking-water, but also accidental ingestion of bathing-water, including swimming pools. It is therefore important to be able to detect these parasites quickly, so that remedial action can be taken to reduce the risk of infection. The proposed system combines multiple-angle scattering detection of a single and two wavelengths, to collect relative wavelength angle-resolved scattering phase functions from tested suspension, and multivariate data analysis techniques to obtain characterizing information of samples under investigation. The system was designed to be simple, portable and inexpensive. It employs two diode lasers (violet InGaN-based and red AlGaInP-based) as light sources and silicon photodiodes as detectors and optical components, all of which are readily available. The measured scattering patterns using the dual wavelength system showed that the relative wavelength angle-resolved scattering pattern of cryptosporidium oocysts was significantly different from other particles (e.g. polystyrene latex sphere, E.coli). The single wavelength set up was applied for cryptosporidium oocysts'size and relative refractive index measurement and differential measurement of the concentration of cryptosporidium oocysts suspended in water and mixed polystyrene latex sphere suspension. The measurement results showed good agreement with the control reference values. These results indicate that the proposed method could potentially be applied to online detection in a water quality control system.
International Nuclear Information System (INIS)
Tornow, W.; Mertens, G.
1977-01-01
In order to study multiple scattering effects both in the gas and particularly in the solid materials of high-pressure gas scintillators, two asymmetry experiments have been performed by scattering of 15.6 MeV polarized neutrons from helium contained in stainless steel vessels of different wall thicknesses. A monte Carlo computer code taking into account the polarization dependence of the differential scattering cross sections has been written to simulate the experiments and to calculate corrections for multiple scattering on helium, xenon and the gas containment materials. Besides the asymmetries for the various scattering processes involved, the code yields time-of-flight spectra of the scattered neutrons and pulse height spectra of the helium recoil nuclei in the gas scintillator. The agreement between experimental results and Monte Carlo calculations is satisfactory. (Auth.)
International Nuclear Information System (INIS)
Dehmer, J.L.; Dill, D.
1974-01-01
A prototype calculation of the well-known 2.5-eV shape resonance in e-N 2 scattering was performed to test the usefulness of the multiple-scattering method for electronic continuum molecular wavefunctions. The results of this demanding test are very encouraging. (U.S.)
Characterisation of ultrasonic structural noise in multiple scattering media using phased arrays
International Nuclear Information System (INIS)
Bedetti, T; Dorval, V; Jenson, F; Derode, A
2013-01-01
The ultrasonic inspection of multiple scattering media gives rise to structural noise which makes it difficult to detect potential damage or crack inside the component. In order to predict the performances of ultrasonic inspection over such complex media, scattering models can be used. Such models rely on specific key parameters describing the multiple scattering process, which can be determined by specific measurements and post-processing techniques. Such experiments were carried out on stainless steel plates using linear phased-arrays. They consist in recording the response matrix constituted by impulse responses between all the elements of the array. By conducting post-processing on this matrix, we measure the elastic mean free path l e and the correlation distance d c of the recorded noise. Additionally, the dynamic behaviour of the coherent backscattering effect was studied in order to measure the diffusion constant D. Plane-wave beamforming has been applied to the response matrix to improve the angular resolution and the signal-to-noise ratio of the backscattered intensity. Details of postprocessing techniques will be shown
Multiple-scattering analysis of laser-beam propagation in the atmosphere and through obscurants
International Nuclear Information System (INIS)
Zardecki, A.; Gerstl, S.A.W.
1983-01-01
The general purpose, discrete-ordinates transport code TWOTRAN is applied to describe the propagation and multiple scattering of a laser beam in a nonhomogeneous aerosol medium. For the medium composed of smoke, haze, and a rain cloud, the problem of the target detectability in a realistic atmospheric scenario is addressed and solved. The signals reflected from the target vs the signals scattered from the smoke cloud are analyzed as a function of the smoke concentration. By calculating the average intensity and a correction factor in the x-y and r-z geometries, the consistency of the rectangular and cylindrical geometry models is assessed. Received power for a detector with a small field of view is computed on a sphere of 1-km radius around the laser source for the Air Force Geophysics Laboratory rural aerosol model with extinction coefficients of 4 km - 1 and 10 km - 1 . This computation allows us to study the received power as a function of the angle between the detector and source axes. The correction factor describing the multiple-scattering enhancement with respect to the simple Lambert-Beer law is introduced, and its calculation is employed to validate the use of the small-angle approximation for the transmissometer configuration. An outline of the theory for a finite field of view detector is followed by numerical results pertaining to the received power and intensity for various aerosol models. Recommendations regarding future work are also formulated
Compton scatter correction in case of multiple crosstalks in SPECT imaging.
Sychra, J J; Blend, M J; Jobe, T H
1996-02-01
A strategy for Compton scatter correction in brain SPECT images was proposed recently. It assumes that two radioisotopes are used and that a significant portion of photons of one radioisotope (for example, Tc99m) spills over into the low energy acquisition window of the other radioisotope (for example, Tl201). We are extending this approach to cases of several radioisotopes with mutual, multiple and significant photon spillover. In the example above, one may correct not only the Tl201 image but also the Tc99m image corrupted by the Compton scatter originating from the small component of high energy Tl201 photons. The proposed extension is applicable to other anatomical domains (cardiac imaging).
Scattering by multiple parallel radially stratified infinite cylinders buried in a lossy half space.
Lee, Siu-Chun
2013-07-01
The theoretical solution for scattering by an arbitrary configuration of closely spaced parallel infinite cylinders buried in a lossy half space is presented in this paper. The refractive index and permeability of the half space and cylinders are complex in general. Each cylinder is radially stratified with a distinct complex refractive index and permeability. The incident radiation is an arbitrarily polarized plane wave propagating in the plane normal to the axes of the cylinders. Analytic solutions are derived for the electric and magnetic fields and the Poynting vector of backscattered radiation emerging from the half space. Numerical examples are presented to illustrate the application of the scattering solution to calculate backscattering from a lossy half space containing multiple homogeneous and radially stratified cylinders at various depths and different angles of incidence.
On the solution of a few problems of multiple scattering by Monte Carlo method
International Nuclear Information System (INIS)
Bluet, J.C.
1966-02-01
Three problems of multiple scattering arising from neutron cross sections experiments, are reported here. The common hypothesis are: - Elastic scattering is the only possible process - Angular distributions are isotropic - Losses of particle energy are negligible in successive collisions. In the three cases practical results, corresponding to actual experiments are given. Moreover the results are shown in more general way, using dimensionless variable such as the ratio of geometrical dimensions to neutron mean free path. The FORTRAN codes are given together with to the corresponding flow charts, and lexicons of symbols. First problem: Measurement of sodium capture cross-section. A sodium sample of given geometry is submitted to a neutron flux. Induced activity is then measured by means of a sodium iodide cristal. The distribution of active nuclei in the sample, and the counter efficiency are calculated by Monte-Carlo method taking multiple scattering into account. Second problem: absolute measurement of a neutron flux using a glass scintillator. The scintillator is a use of lithium 6 loaded glass, submitted to neutron flux perpendicular to its plane faces. If the glass thickness is not negligible compared with scattering mean free path λ, the mean path e' of neutrons in the glass is different from the thickness. Monte-Carlo calculation are made to compute this path and a relative correction to efficiency equal to (e' - e)/e. Third problem: study of a neutron collimator. A neutron detector is placed at the bottom of a cylinder surrounded with water. A neutron source is placed on the cylinder axis, in front of the water shield. The number of neutron tracks going directly and indirectly through the water from the source to the detector are counted. (author) [fr
Full-potential multiple scattering theory with space-filling cells for bound and continuum states.
Hatada, Keisuke; Hayakawa, Kuniko; Benfatto, Maurizio; Natoli, Calogero R
2010-05-12
We present a rigorous derivation of a real-space full-potential multiple scattering theory (FP-MST) that is free from the drawbacks that up to now have impaired its development (in particular the need to expand cell shape functions in spherical harmonics and rectangular matrices), valid both for continuum and bound states, under conditions for space partitioning that are not excessively restrictive and easily implemented. In this connection we give a new scheme to generate local basis functions for the truncated potential cells that is simple, fast, efficient, valid for any shape of the cell and reduces to the minimum the number of spherical harmonics in the expansion of the scattering wavefunction. The method also avoids the need for saturating 'internal sums' due to the re-expansion of the spherical Hankel functions around another point in space (usually another cell center). Thus this approach provides a straightforward extension of MST in the muffin-tin (MT) approximation, with only one truncation parameter given by the classical relation l(max) = kR(b), where k is the electron wavevector (either in the excited or ground state of the system under consideration) and R(b) is the radius of the bounding sphere of the scattering cell. Moreover, the scattering path operator of the theory can be found in terms of an absolutely convergent procedure in the l(max) --> ∞ limit. Consequently, this feature provides a firm ground for the use of FP-MST as a viable method for electronic structure calculations and makes possible the computation of x-ray spectroscopies, notably photo-electron diffraction, absorption and anomalous scattering among others, with the ease and versatility of the corresponding MT theory. Some numerical applications of the theory are presented, both for continuum and bound states.
International Nuclear Information System (INIS)
Curiel-Garcia, Quiela-Marina
2014-01-01
One of the goals of the COMPASS experience is the study of the nucleon spin structure. Data were taken from a polarized muon beam (160 GeV/c) scattering off a polarized target ( 6 LiD or NH 3 ). In this context, the need of a precise knowledge of quark Fragmentation Functions (final-state hadronization of quarks q into hadrons h, FFs) was raised. The FFs can be extracted from hadron multiplicities produced in Semi-Inclusive Deep Inelastic Scattering (SIDIS). This thesis presents the measurement of charged hadrons (pions and kaons) multiplicities from SIDIS data collected in 2006. The data cover a large kinematical range: Q 2 ≥1 (GeV/c)2, y belongs to [0.1,0.9], x belongs to [0.004,0.7] and W belongs to [5,17] GeV. These multiplicities provide an important input for global QCD analyses of world data at NLO, aiming at the FFs determination. (author) [fr
Modified random hinge transport mechanics and multiple scattering step-size selection in EGS5
International Nuclear Information System (INIS)
Wilderman, S.J.; Bielajew, A.F.
2005-01-01
The new transport mechanics in EGS5 allows for significantly longer electron transport step sizes and hence shorter computation times than required for identical problems in EGS4. But as with all Monte Carlo electron transport algorithms, certain classes of problems exhibit step-size dependencies even when operating within recommended ranges, sometimes making selection of step-sizes a daunting task for novice users. Further contributing to this problem, because of the decoupling of multiple scattering and continuous energy loss in the dual random hinge transport mechanics of EGS5, there are two independent step sizes in EGS5, one for multiple scattering and one for continuous energy loss, each of which influences speed and accuracy in a different manner. Further, whereas EGS4 used a single value of fractional energy loss (ESTEPE) to determine step sizes at all energies, to increase performance by decreasing the amount of effort expended simulating lower energy particles, EGS5 permits the fractional energy loss values which are used to determine both the multiple scattering and continuous energy loss step sizes to vary with energy. This results in requiring the user to specify four fractional energy loss values when optimizing computations for speed. Thus, in order to simplify step-size selection and to mitigate step-size dependencies, a method has been devised to automatically optimize step-size selection based on a single material dependent input related to the size of problem tally region. In this paper we discuss the new transport mechanics in EGS5 and describe the automatic step-size optimization algorithm. (author)
Multiple X-ray tomography using transmitted, scattered and fluorescent radiation
International Nuclear Information System (INIS)
Cesareo, R.; Brunetti, A.; Golosio, B.; Lopes, R.T.; Barroso, R.C.; Donativi, M.; Castellano, A.; Quarta, S.
2003-01-01
A multiple CT-scanner is described, which contemporaneously uses transmitted, scattered and fluorescent X-rays for Imaging. The scanner is characterized by a small size X-ray tube and by four detectors: a ''pencil'' X-ray NaI(Tl) for transmitted tomography, a larger size NaI(Tl) for 90 C o Compton tomography, a thermoelectrically cooled Si-PIN or CdZnTe for fluorescent imaging and a CdZnTe for Rayleigh (or diffraction) tomography. Examples of applications are shown
Multiple-scattering and DV-Xα analyses of a Cl-passivated Ge(111) surface
International Nuclear Information System (INIS)
Cao, S; Tang, J-C; Shen, S-L
2003-01-01
The multiple-scattering cluster and DV-Xα methods have been employed to analyse the chlorine 1s near edge x-ray absorption fine structure (NEXAFS) of a Cl-passivated Ge(111) surface. Our detailed analysis demonstrates how the chlorine atoms form a perfect monochloride structure with Cl bonding to the topmost Ge atom. Our calculation reveals the interaction in the chlorine layer is multipolar electrostatic forces. Furthermore, the DV-Xα cluster calculation shows that the orbital contour of the sharp Cl-Ge resonance exhibits a global symmetry, which confirms it to be σ * -like. The above studies are found to enrich previous experimental NEXAFS investigations
Topological cross sections in hadron-nucleus collisions and multiple scattering theory
International Nuclear Information System (INIS)
Zoller, V.R.
1987-01-01
The multiple scattering theory supplemented with cutting rules of Abramovsky, V.A., Gribov, V.N., Kancheli, O.V. is applied to calculation of the hadron-nucleus interaction cross sections. In contrast to standard Glauber approach neither smalness of the interaction radius compared to the nuclear radii nor Gaussian form of the hN-interaction profile function are assumed. The theory of the supercritical pomeron are used. However all the results are more general and do not depend on the parametrization of the pomeron pole amplitude. The region of validity of the widely used approximate formulae for topological and total hA-interaction cross sections are discussed
Energy Technology Data Exchange (ETDEWEB)
Wielunski, L S [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics
1997-12-31
The sensitivity of hydrogen elastic recoil detection ( ERD ) is usually limited by the low energy background in the ERD spectrum. A number of 4.5 MeV He{sup ++} hydrogen ERD spectra from different hydrogen implanted samples are compared. The samples are chosen with different atomic numbers from low Z (carbon) to high Z (tungsten carbide) to observe the effects of multiple scattering and double scattering within the sample material. The experimental depth resolution and levels of the low energy background in ERD spectra are compared with theoretical predictions from multiple and double scattering. 10 refs., 2 tabs., 5 figs.
Energy Technology Data Exchange (ETDEWEB)
Wielunski, L.S. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics
1996-12-31
The sensitivity of hydrogen elastic recoil detection ( ERD ) is usually limited by the low energy background in the ERD spectrum. A number of 4.5 MeV He{sup ++} hydrogen ERD spectra from different hydrogen implanted samples are compared. The samples are chosen with different atomic numbers from low Z (carbon) to high Z (tungsten carbide) to observe the effects of multiple scattering and double scattering within the sample material. The experimental depth resolution and levels of the low energy background in ERD spectra are compared with theoretical predictions from multiple and double scattering. 10 refs., 2 tabs., 5 figs.
Otsuki, Soichi
2016-02-01
This paper presents a theory describing totally incoherent multiple scattering of turbid spherical samples. It is proved that if reciprocity and mirror symmetry hold for single scattering by a particle, they also hold for multiple scattering in spherical samples. Monte Carlo simulations generate a reduced effective scattering Mueller matrix, which virtually satisfies reciprocity and mirror symmetry. The scattering matrix was factorized by using the symmetric decomposition in a predefined form, as well as the Lu-Chipman polar decomposition, approximately into a product of a pure depolarizer and vertically oriented linear retarding diattenuators. The parameters of these components were calculated as a function of the polar angle. While the turbid spherical sample is a pure depolarizer at low polar angles, it obtains more functions of the retarding diattenuator with increasing polar angle.
Factors affecting bone mineral density in multiple sclerosis patients
Ayatollahi, Azin; Mohajeri-Tehrani, Mohammad Reza
2013-01-01
Background Multiple sclerosis (MS) is a demyelinating disease which can cause many disabilities for the patient. Recent data suggests that MS patients have higher risk for osteoporosis. This study was performed to investigate if the osteoporosis prevalence is higher in MS patients and to determine the possible factors affecting bone mineral density (BMD). Methods 51 definite relapsing-remitting MS patients according to McDonald's criteria (45 females, 6 males aged between 20 and 50 years) participated in this study. The control group included 407 females aged from 20 to 49 years; they were healthy and had no history of the diseases affecting bone metabolism. Femoral and lumbar BMD were measured by Dual Energy X-ray Absorptiometry (DXA). The disability of MS patients was evaluated by Expanded Disability Status Scale (EDSS). The patient's quality of life was evaluated by the validated Persian version of multiple sclerosis impact scale (MSIS-29). Results Patients’ mean age was 36 ± 3.3 years and their mean disease duration was 8.7 ± 1.7 years. The mean EDSS score and the mean body mass index (BMI) of the patients were 3 ± 0.9 and 23.5 ± 2.3 kg/m2, respectively. 29% of the patients had never been treated by ß-interferon and 6% of them had not received glucocorticoids (GCs) pulses since their MS had been diagnosed. 26% of the patients had a history of fracture.18% of our patients were osteoporotic and 43% of them were osteopenic. Femoral BMD was significantly lower among MS patients than age matched controls (P < 0.001), but lumbar BMD showed no difference. There was no correlation between administration of GCs pulses, interferon and BMD; however, we found a significant correlation between EDSS score, quality of life (QoL), disease duration and BMD of both site. Conclusion As a result of this study, bone loss inevitably occurs in MS patients. The major factor of BMD loss is immobility. Osteoporosis should be managed as part of MS patients’ treatment protocols
A MULTIPLE SCATTERING POLARIZED RADIATIVE TRANSFER MODEL: APPLICATION TO HD 189733b
Energy Technology Data Exchange (ETDEWEB)
Kopparla, Pushkar; Yung, Yuk L. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA (United States); Natraj, Vijay; Swain, Mark R. [Jet Propulsion Laboratory (NASA-JPL), Pasadena, CA (United States); Zhang, Xi [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ (United States); Wiktorowicz, Sloane J., E-mail: pkk@gps.caltech.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA (United States)
2016-01-20
We present a multiple scattering vector radiative transfer model that produces disk integrated, full phase polarized light curves for reflected light from an exoplanetary atmosphere. We validate our model against results from published analytical and computational models and discuss a small number of cases relevant to the existing and possible near-future observations of the exoplanet HD 189733b. HD 189733b is arguably the most well observed exoplanet to date and the only exoplanet to be observed in polarized light, yet it is debated if the planet’s atmosphere is cloudy or clear. We model reflected light from clear atmospheres with Rayleigh scattering, and cloudy or hazy atmospheres with Mie and fractal aggregate particles. We show that clear and cloudy atmospheres have large differences in polarized light as compared to simple flux measurements, though existing observations are insufficient to make this distinction. Futhermore, we show that atmospheres that are spatially inhomogeneous, such as being partially covered by clouds or hazes, exhibit larger contrasts in polarized light when compared to clear atmospheres. This effect can potentially be used to identify patchy clouds in exoplanets. Given a set of full phase polarimetric measurements, this model can constrain the geometric albedo, properties of scattering particles in the atmosphere, and the longitude of the ascending node of the orbit. The model is used to interpret new polarimetric observations of HD 189733b in a companion paper.
Wang, Zuowei; Biwa, Shiro
2018-03-01
A numerical procedure is proposed for the multiple scattering analysis of flexural waves on a thin plate with circular holes based on the Kirchhoff plate theory. The numerical procedure utilizes the wave function expansion of the exciting as well as scattered fields, and the boundary conditions at the periphery of holes are incorporated as the relations between the expansion coefficients of exciting and scattered fields. A set of linear algebraic equations with respect to the wave expansion coefficients of the exciting field alone is established by the numerical collocation method. To demonstrate the applicability of the procedure, the stop band characteristics of flexural waves are analyzed for different arrangements and concentrations of circular holes on a steel plate. The energy transmission spectra of flexural waves are shown to capture the detailed features of the stop band formation of regular and random arrangements of holes. The increase of the concentration of holes is found to shift the dips of the energy transmission spectra toward higher frequencies as well as deepen them. The hexagonal hole arrangement can form a much broader stop band than the square hole arrangement for flexural wave transmission. It is also demonstrated that random arrangements of holes make the transmission spectrum more complicated.
Multiple Coulomb scattering of high-energy heavy charged particle beams used in biology and medicine
International Nuclear Information System (INIS)
Wong, M.; Schimmerling, W.; Ludewigt, B.; Phillips, M.; Curtis, S.; Tobias, C.A.
1987-01-01
The authors measured lateral displacement and angular distributions of high-energy heavy charged particles emerging from a target at the Lawrence Berkeley Laboratory BEVALAC with beams used in radiobiology experiments. Multiple Coulomb scattering occurring in the target material generally spreads the beam laterally and increases its divergence. The apparatus consists of four sets of position-sensitive semiconductor detectors located along the beam line. Each providing two position signals and one energy signal. The difference between the two position signals is used to determine the particle position in one dimension. The two position signals are constrained to add up to the energy deposition signal in order to reject multiple-particle traversals. The vector directions for the incident and emerging particles are reconstructed in three dimensions from their measured coordinated positions. Lateral and angular distributions are reported for beams of high-energy neon, iron and uranium ions incident on targets of aluminum, cooper, lead and water
Energy dependence of the charged multiplicity in deep inelastic scattering at HERA
Energy Technology Data Exchange (ETDEWEB)
Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)
2008-03-15
The charged multiplicity distributions and the mean charged multiplicity have been investigated in inclusive neutral current deep inelastic ep scattering with the ZEUS detector at HERA, using an integrated luminosity of 38.6 pb{sup -1}. The measurements were performed in the current region of the Breit frame, as well as in the current fragmentation region of the hadronic centre-of-mass frame. The KNO-scaling properties of the data were investigated and the energy dependence was studied using different energy scales. The data are compared to results obtained in e{sup +}e{sup -} collisions and to previous DIS measurements as well as to leading-logarithm parton-shower Monte Carlo predictions. (orig.)
Energy dependence of the charged multiplicity in deep inelastic scattering at HERA
International Nuclear Information System (INIS)
Chekanov, S.; Derrick, M.; Magill, S.
2008-03-01
The charged multiplicity distributions and the mean charged multiplicity have been investigated in inclusive neutral current deep inelastic ep scattering with the ZEUS detector at HERA, using an integrated luminosity of 38.6 pb -1 . The measurements were performed in the current region of the Breit frame, as well as in the current fragmentation region of the hadronic centre-of-mass frame. The KNO-scaling properties of the data were investigated and the energy dependence was studied using different energy scales. The data are compared to results obtained in e + e - collisions and to previous DIS measurements as well as to leading-logarithm parton-shower Monte Carlo predictions. (orig.)
Multiple solutions to dense systems in radar scattering using a preconditioned block GMRES solver
Energy Technology Data Exchange (ETDEWEB)
Boyse, W.E. [Advanced Software Resources, Inc., Santa Clara, CA (United States)
1996-12-31
Multiple right-hand sides occur in radar scattering calculations in the computation of the simulated radar return from a body at a large number of angles. Each desired angle requires a right-hand side vector to be computed and the solution generated. These right-hand sides are naturally smooth functions of the angle parameters and this property is utilized in a novel way to compute solutions an order of magnitude faster than LINPACK The modeling technique addressed is the Method of Moments (MOM), i.e. a boundary element method for time harmonic Maxwell`s equations. Discretization by this method produces general complex dense systems of rank 100`s to 100,000`s. The usual way to produce the required multiple solutions is via LU factorization and solution routines such as found in LINPACK. Our method uses the block GMRES iterative method to directly iterate a subset of the desired solutions to convergence.
Multiple expulsions. Affective and material evictions in Calais
Directory of Open Access Journals (Sweden)
Francesca Ansaloni
2017-06-01
Full Text Available If we regard expulsions as the abrupt interruption along the territorialisation process of any body in search of refuge, we could see displaced people and migrants as those figures that have to cope with multiple expulsions until they can build a less vulnerable and precarious territory. Drawing on an ethnographic fieldwork in the makeshift camp of Calais known as the Jungle, I outline a relentless movement of expulsion-inclusion, which is both material and affective and operates on different dimensions. In the Jungle of Calais, from March 2015 to October 2016 lived thousands of people coming mainly from Afghanistan, Sudan, Ethiopia, Eritrea, and Pakistan, who created a city-like system together with volunteers from UK and France. Both the French state and the aid groups built their own territories by establishing different kind of relations with the residents of the Jungle, thus contributing to (at least temporarily stabilise or destabilise their search for a territory of their own and engaging in less visible practices of expulsion.
Reichardt, J; Hess, M; Macke, A
2000-04-20
Multiple-scattering correction factors for cirrus particle extinction coefficients measured with Raman and high spectral resolution lidars are calculated with a radiative-transfer model. Cirrus particle-ensemble phase functions are computed from single-crystal phase functions derived in a geometrical-optics approximation. Seven crystal types are considered. In cirrus clouds with height-independent particle extinction coefficients the general pattern of the multiple-scattering parameters has a steep onset at cloud base with values of 0.5-0.7 followed by a gradual and monotonic decrease to 0.1-0.2 at cloud top. The larger the scattering particles are, the more gradual is the rate of decrease. Multiple-scattering parameters of complex crystals and of imperfect hexagonal columns and plates can be well approximated by those of projected-area equivalent ice spheres, whereas perfect hexagonal crystals show values as much as 70% higher than those of spheres. The dependencies of the multiple-scattering parameters on cirrus particle spectrum, base height, and geometric depth and on the lidar parameters laser wavelength and receiver field of view, are discussed, and a set of multiple-scattering parameter profiles for the correction of extinction measurements in homogeneous cirrus is provided.
Multiple-scattering formalism for correlated systems: A KKR-DMFT approach
International Nuclear Information System (INIS)
Minar, J.; Perlov, A.; Ebert, H.; Chioncel, L.; Katsnelson, M. I.; Lichtenstein, A.I.
2005-01-01
We present a charge and self-energy self-consistent computational scheme for correlated systems based on the Korringa-Kohn-Rostoker (KKR) multiple scattering theory with the many-body effects described by the means of dynamical mean field theory (DMFT). The corresponding local multiorbital and energy dependent self-energy is included into the set of radial differential equations for the single-site wave functions. The KKR Green's function is written in terms of the multiple scattering path operator, the later one being evaluated using the single-site solution for the t-matrix that in turn is determined by the wave functions. An appealing feature of this approach is that it allows to consider local quantum and disorder fluctuations on the same footing. Within the coherent potential approximation (CPA) the correlated atoms are placed into a combined effective medium determined by the DMFT self-consistency condition. Results of corresponding calculations for pure Fe, Ni, and Fe x Ni 1-x alloys are presented
The Over-Barrier Resonant States and Multi-Channel Scattering in Multiple Quantum Wells
Directory of Open Access Journals (Sweden)
A Polupanov
2016-09-01
Full Text Available We demonstrate an explicit numerical method for accurate calculation of the scattering matrix and its poles, and apply this method to describe the multi-channel scattering in the multiple quantum-wells structures. The S-matrix is continued analytically to the unphysical region of complex energy values. Results of calculations show that there exist one or more S-matrix poles, corresponding to the over-barrier resonant states critical for the effect of the absolute reflection of holes in the energy range where only the heavy ones may propagate over barriers in a structure. Light- and heavy-hole states are described by the Luttinger Hamiltonian matrix. In contrast to the single quantum-well case, at some parameters of a multiple quantum-wells structure the number of S-matrix poles may exceed that of the absolute reflection peaks, and at different values of parameters the absolute reflection peak corresponds to different resonant states. The imaginary parts of the S-matrix poles and hence the lifetimes of resonant states as well as the widths of resonant peaks of absolute reflection depend drastically on the quantum-well potential depth. In the case of shallow quantum wells there is in fact a long-living over-barrier resonant hole state.
Spectrometer for Particle Characterization With a New Multiple-Scattering Theory, Phase I
National Aeronautics and Space Administration — There are two major commercial types of light-scattering particle size analyzers: Static Light Scattering and Dynamic Light Scattering. They are expensive, delicate,...
Mitri, F. G.
2017-08-01
The multiple scattering effects occurring between two scatterers are described based upon the multipole expansion formalism as well as the addition theorem of cylindrical wave functions. An original approach is presented in which an effective incident acoustic field on a particular object, which includes both the primary and re-scattered waves from the other particle is determined first, and then used with the scattered field to derive closed-form analytical expressions for the inherent (i.e. intrinsic) cross-sections based on the far-field scattering. This method does not introduce any approximation in the calculation of the intrinsic cross-sections since the procedure is reduced to the one-body problem. The mathematical expressions for the intrinsic cross-sections are formulated in partial-wave series expansions (PWSEs) in cylindrical coordinates involving the angle of incidence, the addition theorem for the cylindrical wave functions, and the expansion coefficients of the scatterers. Numerical examples illustrate the analysis for two rigid circular cylindrical cross-sections with different radii immersed in a non-viscous fluid. Computations for the dimensionless extrinsic and intrinsic extinction cross-section factors are evaluated with particular emphasis on varying the angle of incidence, the interparticle distance, as well as the sizes of the particles. A symmetric behavior is observed for the dimensionless extrinsic extinction cross-section, while asymmetry arises for the intrinsic extinction cross-section of each particle with respect to the angle of incidence. The present analysis provides a complete analytical and computational method for the prediction of the intrinsic (local) scattering, absorption and extinction cross-sections in the multiple acoustic scatterings of plane progressive waves of arbitrary incidence by a pair of scatterers. The results and computational analyses can be used as a priori information for future applications to guide the
International Nuclear Information System (INIS)
Mitri, F G
2017-01-01
The multiple scattering effects occurring between two scatterers are described based upon the multipole expansion formalism as well as the addition theorem of cylindrical wave functions. An original approach is presented in which an effective incident acoustic field on a particular object, which includes both the primary and re-scattered waves from the other particle is determined first, and then used with the scattered field to derive closed-form analytical expressions for the inherent (i.e. intrinsic) cross-sections based on the far-field scattering. This method does not introduce any approximation in the calculation of the intrinsic cross-sections since the procedure is reduced to the one-body problem. The mathematical expressions for the intrinsic cross-sections are formulated in partial-wave series expansions (PWSEs) in cylindrical coordinates involving the angle of incidence, the addition theorem for the cylindrical wave functions, and the expansion coefficients of the scatterers. Numerical examples illustrate the analysis for two rigid circular cylindrical cross-sections with different radii immersed in a non-viscous fluid. Computations for the dimensionless extrinsic and intrinsic extinction cross-section factors are evaluated with particular emphasis on varying the angle of incidence, the interparticle distance, as well as the sizes of the particles. A symmetric behavior is observed for the dimensionless extrinsic extinction cross-section, while asymmetry arises for the intrinsic extinction cross-section of each particle with respect to the angle of incidence. The present analysis provides a complete analytical and computational method for the prediction of the intrinsic (local) scattering, absorption and extinction cross-sections in the multiple acoustic scatterings of plane progressive waves of arbitrary incidence by a pair of scatterers. The results and computational analyses can be used as a priori information for future applications to guide the
Track reconstruction for the Mu3e experiment based on a novel Multiple Scattering fit
Directory of Open Access Journals (Sweden)
Kozlinskiy Alexandr
2017-01-01
Full Text Available The Mu3e experiment is designed to search for the lepton flavor violating decay μ+ → e+e+e−. The aim of the experiment is to reach a branching ratio sensitivity of 10−16. In a first phase the experiment will be performed at an existing beam line at the Paul-Scherrer Institute (Switzerland providing 108 muons per second, which will allow to reach a sensitivity of 2 · 10−15. The muons with a momentum of about 28 MeV/c are stopped and decay at rest on a target. The decay products (positrons and electrons with energies below 53MeV are measured by a tracking detector consisting of two double layers of 50 μm thin silicon pixel sensors. The high granularity of the pixel detector with a pixel size of 80 μm × 80 μm allows for a precise track reconstruction in the high multiplicity environment of the Mu3e experiment, reaching 100 tracks per reconstruction frame of 50 ns in the final phase of the experiment. To deal with such high rates and combinatorics, the Mu3e track reconstruction uses a novel fit algorithm that in the simplest case takes into account only the multiple scattering, which allows for a fast online tracking on a GPU based filter farm. An implementation of the 3-dimensional multiple scattering fit based on hit triplets is described. The extension of the fit that takes into account energy losses and pixel size is used for offline track reconstruction. The algorithm and performance of the offline track reconstruction based on a full Geant4 simulation of the Mu3e detector are presented.
International Nuclear Information System (INIS)
Neumayer, P
2007-01-01
A long-standing problem in the field of laser-plasma interactions is to successfully employ multiple-ion species plasmas to reduce stimulated Brillouin scattering (SBS) in inertial confinement fusion (ICF) hohlraum conditions. Multiple-ion species increase significantly the linear Landau damping for acoustic waves. Consequently, recent hohlraum designs for indirect-drive ignition on the National Ignition Facility investigate wall liner material options so that the liner gain for parametric instabilities will be below threshold for the onset SBS. Although the effect of two-ion species plasmas on Landau damping has been directly observed with Thomson scattering, early experiments on SBS in these plasmas have suffered from competing non-linear effects or laser beam filamentation. In this study, a reduction of SBS scattering to below the percent level has been observed in hohlraums at Omega that emulate the plasma conditions in an indirect drive ICF experiments. These experiments have measured the laser-plasma interaction processes in ignition-relevant high-electron temperature regime demonstrating Landau damping as a controlling process for SBS. The hohlraums have been filled with various fractions of CO 2 and C 3 H 8 varying the ratio of the light (H) to heavy (C and O) ion density from 0 to 2.6. They have been heated by 14.5 kJ of 351-nm light, thus increasing progressively Landau damping by an order of magnitude at constant electron density and temperature. A delayed 351-nm interaction beam, spatially smoothed to produce a 200-(micro)m laser spot at best focus, has propagated along the axis of the hohlraum. The backscattered light, both into the lens and outside, the transmitted light through the hohlraum plasma and the radiation temperature of the hohlraum has been measured. For ignition relevant laser intensities (3-9 10 14 Wcm -2 ), we find that the SBS reflectivity scales as predicted with Landau damping from >30% to <1%. Simultaneously, the hohlraum radiation
Analysis of multiple scattering contributions in electron-impact ionization of molecular hydrogen
Ren, Xueguang; Hossen, Khokon; Wang, Enliang; Pindzola, M. S.; Dorn, Alexander; Colgan, James
2017-10-01
We report a combined experimental and theoretical study on the low-energy (E 0 = 31.5 eV) electron-impact ionization of molecular hydrogen (H2). Triple differential cross sections are measured for a range of fixed emission angles of one outgoing electron between {θ }1=-70^\\circ and -130° covering the full 4π solid angle of the second electron. The energy sharing of the outgoing electrons varies from symmetric ({E}1={E}2=8 eV) to highly asymmetric (E 1 = 1 eV and E 2 = 15 eV). In addition to the binary and recoil lobes, a structure is observed perpendicular to the incoming beam direction which is due to multiple scattering of the projectile inside the molecular potential. The absolutely normalized experimental cross sections are compared with results from the time-dependent close-coupling (TDCC) calculations. Molecular alignment dependent TDCC results demonstrate that these structures are only present if the molecule axis is lying in the scattering plane.
Angular distribution of diffuse reflectance from incoherent multiple scattering in turbid media.
Gao, M; Huang, X; Yang, P; Kattawar, G W
2013-08-20
The angular distribution of diffuse reflection is elucidated with greater understanding by studying a homogeneous turbid medium. We modeled the medium as an infinite slab and studied the reflection dependence on the following three parameters: the incident direction, optical depth, and asymmetry factor. The diffuse reflection is produced by incoherent multiple scattering and is solved through radiative transfer theory. At large optical depths, the angular distribution of the diffuse reflection with small incident angles is similar to that of a Lambertian surface, but, with incident angles larger than 60°, the angular distributions have a prominent reflection peak around the specular reflection angle. These reflection peaks are found originating from the scattering within one transport mean free path in the top layer of the medium. The maximum reflection angles for different incident angles are analyzed and can characterize the structure of angular distributions for different asymmetry factors and optical depths. The properties of the angular distribution can be applied to more complex systems for a better understanding of diffuse reflection.
Measurement of Hadron Multiplicities in Deep Inelastic Muon-Nucleon Scattering
du Fresne von Hohenesche, Nicolas
2016-06-02
In deep-inelastic muon-nucleon scattering, a single quark can be ejected out of the nucleon by the absorption of a high-energy photon. Such a free isolated quark has never been observed in nature. In quantum chromodynamics (QCD), coloured objects, such as a single quark, create additional quark anti-quark pairs out of the colour field and the final state comprises a jet of hadrons. The hadronisation process can be described by fragmentation functions D_q^h, the probability that a quark with the flavour q turns into a hadron of the type h. Similar to the parton distribution function, the fragmentation functions are fundamental, universal and process-independent quantities. The fragmentation functions are measured with the COM- PASS spectrometer in muon-nucleon scattering. The observables are the hadron multiplicities M_h. The COMPASS experiment consists of a two-stage magnetic spectrometer located at the M2 beam line of the Super Proton Synchrotron at CERN and uses a polarised muon beam on a nuclear fixed targ...
Modified Moliere's screening parameter and its impact on multiple coulomb scattering
International Nuclear Information System (INIS)
Striganov, Sergei
2015-01-01
The Moliere approximation of elastic Coulomb scattering cross-sections plays an important role in accurate description of multiple scattering, non-ionisation energy, DPA radiation damage etc. The cross-section depends only on a single parameter that describes the atomic screening. Moliere calculated the screening angle for the Tomas-Fermi distribution of electrons in atoms. In this paper, the screening parameter was recalculated using a more accurate atomic form-factor obtained from the self-consistent Dirac-Hartree-Fock-Slater computations. For relativistic particles, the new screening angle can differ from the Moliere approximation by up to 50%. At the same time, it is rather close to other independent calculations. At low energies, the new screening angle is different for positrons and electrons. The positron screening parameter is much larger than the electron one for heavy nuclei at energies of ∼Z keV. The impact of the screening angle on particle transport and calculated quantities is discussed. (authors)
Comparison of Geant4 multiple Coulomb scattering models with theory for radiotherapy protons.
Makarova, Anastasia; Gottschalk, Bernard; Sauerwein, Wolfgang
2017-07-06
Usually, Monte Carlo models are validated against experimental data. However, models of multiple Coulomb scattering (MCS) in the Gaussian approximation are exceptional in that we have theories which are probably more accurate than the experiments which have, so far, been done to test them. In problems directly sensitive to the distribution of angles leaving the target, the relevant theory is the Molière/Fano/Hanson variant of Molière theory (Gottschalk et al 1993 Nucl. Instrum. Methods Phys. Res. B 74 467-90). For transverse spreading of the beam in the target itself, the theory of Preston and Koehler (Gottschalk (2012 arXiv:1204.4470)) holds. Therefore, in this paper we compare Geant4 simulations, using the Urban and Wentzel models of MCS, with theory rather than experiment, revealing trends which would otherwise be obscured by experimental scatter. For medium-energy (radiotherapy) protons, and low-Z (water-like) target materials, Wentzel appears to be better than Urban in simulating the distribution of outgoing angles. For beam spreading in the target itself, the two models are essentially equal.
Diffusion equations and hard collisions in multiple scattering of charged particles
International Nuclear Information System (INIS)
Papiez, Lech; Tulovsky, Vladimir
1998-01-01
The processes of angular-spatial evolution of multiple scattering of charged particles are described by the Lewis (special case of Boltzmann) integro-differential equation. The underlying stochastic process for this evolution is the compound Poisson process with transition densities satisfying the Lewis equation. In this paper we derive the Lewis equation from the compound Poisson process and show that the effective method of the solution of this equation can be based on the idea of decomposition of the compound Poisson process into processes of soft and hard collisions. Formulas for transition densities of soft and hard collision processes are provided in this paper together with the formula expressing the general solution of the Lewis equation in terms of those transition densities
Anderson, D. E., Jr.; Meier, R. R.; Hodges, R. R., Jr.; Tinsley, B. A.
1987-01-01
The H Balmer alpha nightglow is investigated by using Monte Carlo models of asymmetric geocoronal atomic hydrogen distributions as input to a radiative transfer model of solar Lyman-beta radiation in the thermosphere and atmosphere. It is shown that it is essential to include multiple scattering of Lyman-beta radiation in the interpretation of Balmer alpha airglow data. Observations of diurnal variation in the Balmer alpha airglow showing slightly greater intensities in the morning relative to evening are consistent with theory. No evidence is found for anything other than a single sinusoidal diurnal variation of exobase density. Dramatic changes in effective temperature derived from the observed Balmer alpha line profiles are expected on the basis of changing illumination conditions in the thermosphere and exosphere as different regions of the sky are scanned.
The Green Function cellular method and its relation to multiple scattering theory
International Nuclear Information System (INIS)
Butler, W.H.; Zhang, X.G.; Gonis, A.
1992-01-01
This paper investigates techniques for solving the wave equation which are based on the idea of obtaining exact local solutions within each potential cell, which are then joined to form a global solution. The authors derive full potential multiple scattering theory (MST) from the Lippmann-Schwinger equation and show that it as well as a closely related cellular method are techniques of this type. This cellular method appears to have all of the advantages of MST and the added advantage of having a secular matrix with only nearest neighbor interactions. Since this cellular method is easily linearized one can rigorously reduce electronic structure calculation to the problem of solving a nearest neighbor tight-binding problem
Diffusion equations and hard collisions in multiple scattering of charged particles
Energy Technology Data Exchange (ETDEWEB)
Papiez, Lech [Department of Radiation Oncology, Indiana University, Indianapolis, IN (United States); Tulovsky, Vladimir [Department of Mathematics, St. John' s College, Staten Island, New York, NY (United States)
1998-09-01
The processes of angular-spatial evolution of multiple scattering of charged particles are described by the Lewis (special case of Boltzmann) integro-differential equation. The underlying stochastic process for this evolution is the compound Poisson process with transition densities satisfying the Lewis equation. In this paper we derive the Lewis equation from the compound Poisson process and show that the effective method of the solution of this equation can be based on the idea of decomposition of the compound Poisson process into processes of soft and hard collisions. Formulas for transition densities of soft and hard collision processes are provided in this paper together with the formula expressing the general solution of the Lewis equation in terms of those transition densities.
Absorption imaging of a quasi-two-dimensional gas: a multiple scattering analysis
International Nuclear Information System (INIS)
Chomaz, L; Corman, L; Yefsah, T; Desbuquois, R; Dalibard, J
2012-01-01
Absorption imaging with quasi-resonant laser light is a commonly used technique for probing ultra-cold atomic gases in various geometries. In this paper, we investigate some non-trivial aspects of this method when applying the method to in situ diagnosis of a quasi-two-dimensional (2D) gas. Using Monte Carlo simulations we study the modification of the absorption cross-section of a photon when it undergoes multiple scattering in the gas. We determine the variations of the optical density with various parameters, such as the detuning of the light from the atomic resonance and the thickness of the gas. We compare our results to the known 3D result (the Beer-Lambert law) and outline the specific features of the 2D case. (paper)
Multiple Scattering Analysis of Cu - K EXAFS in Bi2Sr1.5 Cu2O8+δ
International Nuclear Information System (INIS)
Roehler, J.; Cruesemann, R.
1995-01-01
We have analyzed the Cu K-EXAFS of Bi 2 Sr 1.5 Ca 1.5 Cu 2 O 8+δ using a full multiple scattering analysis in a cluster with diameter d∼ 7.6 A. The layered structure has numerous quasi one-dimensional structural elements which give rise to significant multiple scattering contributions in the EXAFS. We confirm the Sr/Ca ratio of the sample is 1:1, and one Ca atom is located close to a nominal Sr-site. At 40 K the dimpling angle in the CuO 2 -plane is found to be ≤ 3.5 . (author)
International Nuclear Information System (INIS)
Nagamatsu, S.; Ono, M.; Kera, S.; Okudaira, K. K.; Fujikawa, T.; Ueno, N.
2007-01-01
The polarization dependence of F K-edge X-ray absorption near edge structure (XANES) spectra of highly-oriented thin-film of polytetrafluoroethylene (PTFE) has been analyzed by using multiple scattering theory. The spectra show clear polarization dependence due to the highly-oriented structure. The multiple scattering calculations reflects a local structure around an absorbing atom. The calculated results obtained by considering intermolecular-interactions are in good agreement with the observed polarization-dependence. We have also analyzed structural models of the radiation damaged PTFE films
Energy Technology Data Exchange (ETDEWEB)
Berginc, G [THALES, 2 avenue Gay-Lussac 78995 ELANCOURT (France)
2013-11-30
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)
Why does multiple sclerosis only affect human primates?
't Hart, Bert A.
Background: Multiple sclerosis (MS) develops exclusively in humans. Non-human primates are resistant against MS, although they are highly susceptible to the MS animal model, experimental autoimmune encephalomyelitis (EAE). Unravelling of the cause(s) underlying this discrepancy is highly relevant as
International Nuclear Information System (INIS)
Shafiq, A.; Meyer, H.E. de; Grosjean, C.C.
1985-01-01
An approximate model based on an improved diffusion-type theory is established for treating multiple synthetic scattering in a homogeneous slab of finite thickness. As in the case of the exact treatment given in the preceding paper (Part I), it appears possible to transform the considered transport problem into an equivalent fictitious one involving multiple isotropic scattering, therefore permitting the application of an established corrected diffusion theory for treating isotropic scattering taking place in a convex homogeneous medium bounded by a vacuum in the presence of various types of sources. The approximate values of the reflection and transmission coefficients are compared with the rigorous values listed in Part I. In this way, the high accuracy of the approximation is clearly demonstrated. (author)
Influence of multiple well defined conformations on small-angle scattering of proteins in solution.
Heller, William T
2005-01-01
A common structural motif for many proteins comprises rigid domains connected by a flexible hinge or linker. The flexibility afforded by these domains is important for proper function and such proteins may be able to adopt more than one conformation in solution under equilibrium conditions. Small-angle scattering of proteins in solution samples all conformations that exist in the sampled volume during the time of the measurement, providing an ensemble-averaged intensity. In this paper, the influence of sampling an ensemble of well defined protein structures on the small-angle solution scattering intensity profile is examined through common analysis methods. Two tests were performed using simulated data: one with the extended and collapsed states of the bilobal calcium-binding protein calmodulin and the second with the catalytic subunit of protein kinase A, which has two globular domains connected by a glycine hinge. In addition to analyzing the simulated data for the radii of gyration Rg, distance distribution function P(r) and particle volume, shape restoration was applied to the simulated data. Rg and P(r) of the ensemble profiles could be easily mistaken for a single intermediate state. The particle volumes and models of the ensemble intensity profiles show that some indication of multiple conformations exists in the case of calmodulin, which manifests an enlarged volume and shapes that are clear superpositions of the conformations used. The effect on the structural parameters and models is much more subtle in the case of the catalytic subunit of protein kinase A. Examples of how noise influences the data and analyses are also presented. These examples demonstrate the loss of the indications of multiple conformations in cases where even broad distributions of structures exist. While the tests using calmodulin show that the ensemble states remain discernible from the other ensembles tested or a single partially collapsed state, the tests performed using the
Czech Academy of Sciences Publication Activity Database
Adolph, C.; Aghasyan, M.; Akhunzyanov, R.; Alexeev, G. D.; Alexeev, M.; Amoroso, A.; Andrieux, V.; Anfimov, N. V.; Anosov, V.; Augsten, K.; Augustyniak, W.; Austregesilo, A.; Azevedo, C.; Badelek, B.; Balestra, F.; Barth, J.; Beck, D.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E. R.; Birsa, R.; Bisplinghoff, J.; Bodlák, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Büchele, M.; Capozza, L.; Chang, W.-C.; Chatterjee, C.; Chiosso, M.; Choi, I.; Chung, S.U.; Cicuttin, A.; Crespo, M.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O.; Dhara, L.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Eversheim, P.D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; Finger jr., M.; Fischer, H.; Franco, C.; Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmüller, S.; Grasso, A.; Grosse-Perdekapm, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; von Harrach, D.; Hashimoto, R.; Heinsius, F. H.; Heitz, R.; Herrmann, E.; Hinterberger, F.; Horikawa, N.; d'Hose, N.; Hsieh, C.-Yu.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jarý, V.; Joosten, R.; Jörg, P.; Kabuss, E.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Y.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O.; Krämer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z. V.; Kuhn, R.; Kulinich, Y.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lian, Y.-S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G. K.; Marchand, C.; Marianski, B.; Martin, A.; Marzec, J.; Matoušek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, M.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Mikhasenko, M.; Mitrofanov, E.; Mitrofanov, N.; Miyachi, Y.; Montuenga, P.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nikolaenko, V. I.; Nový, J.; Nowak, W. D.; Nukazuka, G.; Nunes, A.S.; Olshevsky, A. G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.-C.; Pereira, F.; Pešek, M.; Peshekhonov, D. V.; Pierre, N.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Roskot, M.; Rossiyskaya, N. S.; Ryabchikov, D.; Rybnikov, A.; Rychter, A.; Salač, R.; Samoylenko, V. D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I. A.; Sawada, T.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schönning, K.; Schopferer, S.; Seder, E.; Selyunin, A.; Shevchenko, O. Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Smolík, J.; Sozzi, F.; Srnka, Aleš; Steffen, D.; Stolarski, M.; Šulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Tasevsky, M.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Tosello, F.; Tskhay, V.; Uhl, S.; Veloso, J.; Virius, M.; Vondra, J.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Ter Wolbeek, J.; Zaremba, K.; Závada, P.; Zavertyaev, M.; Zemlyanichkina, E.; Zhuravlev, N.; Ziembicki, M.; Zink, A.
2017-01-01
Roč. 764, JAN (2017), s. 1-10 ISSN 0370-2693 R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : deep inelastic scattering * pion multiplicities * fragmentation functions Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Nuclear physics Impact factor: 4.807, year: 2016
Le Bihan, Nicolas; Margerin, Ludovic
2009-07-01
In this paper, we present a nonparametric method to estimate the heterogeneity of a random medium from the angular distribution of intensity of waves transmitted through a slab of random material. Our approach is based on the modeling of forward multiple scattering using compound Poisson processes on compact Lie groups. The estimation technique is validated through numerical simulations based on radiative transfer theory.
Velten, Andreas
2017-05-01
Light scattering is a primary obstacle to optical imaging in a variety of different environments and across many size and time scales. Scattering complicates imaging on large scales when imaging through the atmosphere when imaging from airborne or space borne platforms, through marine fog, or through fog and dust in vehicle navigation, for example in self driving cars. On smaller scales, scattering is the major obstacle when imaging through human tissue in biomedical applications. Despite the large variety of participating materials and size scales, light transport in all these environments is usually described with very similar scattering models that are defined by the same small set of parameters, including scattering and absorption length and phase function. We attempt a study of scattering and methods of imaging through scattering across different scales and media, particularly with respect to the use of time of flight information. We can show that using time of flight, in addition to spatial information, provides distinct advantages in scattering environments. By performing a comparative study of scattering across scales and media, we are able to suggest scale models for scattering environments to aid lab research. We also can transfer knowledge and methodology between different fields.
Multiple parton interactions in deep inelastic ep-scattering at HERA
Energy Technology Data Exchange (ETDEWEB)
Osman, Sakar
2008-12-15
The production of jets with low transverse momenta (mini-jets) in deep inelastic electron-proton scattering is studied. The analyses uses data taken with the H1 detector at HERA during the years 1999 to 2000. The events are required to contain either at least one leading jet of P{sub T}>5 GeV (the inclusive 1-jet sample) or at least two hard jets where one of them has to be at an angle larger than 140 degrees with respect to the leading jet (inclusive 2-jet sample). Mini-jet multiplicities and their average transverse momenta are presented as a function of Q{sup 2}, in two regions of psuedo-rapidity and for two bins in the hadronic mass, W for the inclusive 1-jet sample. For the inclusive 2-jet sample the results are shown for direct and resolved photon interactions in two bins of W. The results are compared to various QCD based models. A new method for calibrating jet energy measurements up to 10 GeV has been developed and its performance has been studied. (orig.)
Band structures in a two-dimensional phononic crystal with rotational multiple scatterers
Song, Ailing; Wang, Xiaopeng; Chen, Tianning; Wan, Lele
2017-03-01
In this paper, the acoustic wave propagation in a two-dimensional phononic crystal composed of rotational multiple scatterers is investigated. The dispersion relationships, the transmission spectra and the acoustic modes are calculated by using finite element method. In contrast to the system composed of square tubes, there exist a low-frequency resonant bandgap and two wide Bragg bandgaps in the proposed structure, and the transmission spectra coincide with band structures. Specially, the first bandgap is based on locally resonant mechanism, and the simulation results agree well with the results of electrical circuit analogy. Additionally, increasing the rotation angle can remarkably influence the band structures due to the transfer of sound pressure between the internal and external cavities in low-order modes, and the redistribution of sound pressure in high-order modes. Wider bandgaps are obtained in arrays composed of finite unit cells with different rotation angles. The analysis results provide a good reference for tuning and obtaining wide bandgaps, and hence exploring the potential applications of the proposed phononic crystal in low-frequency noise insulation.
Multiple parton interactions in deep inelastic ep-scattering at HERA
International Nuclear Information System (INIS)
Osman, Sakar
2008-12-01
The production of jets with low transverse momenta (mini-jets) in deep inelastic electron-proton scattering is studied. The analyses uses data taken with the H1 detector at HERA during the years 1999 to 2000. The events are required to contain either at least one leading jet of P T >5 GeV (the inclusive 1-jet sample) or at least two hard jets where one of them has to be at an angle larger than 140 degrees with respect to the leading jet (inclusive 2-jet sample). Mini-jet multiplicities and their average transverse momenta are presented as a function of Q 2 , in two regions of psuedo-rapidity and for two bins in the hadronic mass, W for the inclusive 1-jet sample. For the inclusive 2-jet sample the results are shown for direct and resolved photon interactions in two bins of W. The results are compared to various QCD based models. A new method for calibrating jet energy measurements up to 10 GeV has been developed and its performance has been studied. (orig.)
Multiple parton scattering in nuclei: heavy quark energy loss and modified fragmentation functions
International Nuclear Information System (INIS)
Zhang Benwei; Wang, Enke; Wang Xinnian
2005-01-01
Multiple scattering, induced radiative energy loss and modified fragmentation functions of a heavy quark in nuclear matter are studied within the framework of generalized factorization in perturbative QCD. Modified heavy quark fragmentation functions and energy loss are derived in detail with illustration of the mass dependencies of the Landau-Pomeranchuk-Migdal interference effects and heavy quark energy loss. Due to the quark mass dependence of the gluon formation time, the nuclear size dependencies of nuclear modification of the heavy quark fragmentation function and heavy quark energy loss are found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss of the heavy quark is also significantly suppressed due to limited cone of gluon radiation imposed by the mass. Medium modification of the heavy quark fragmentation functions is found to be limited to the large z region due to the form of heavy quark fragmentation functions in vacuum
Fully-relativistic full-potential multiple scattering theory: A pathology-free scheme
Liu, Xianglin; Wang, Yang; Eisenbach, Markus; Stocks, G. Malcolm
2018-03-01
The Green function plays an essential role in the Korringa-Kohn-Rostoker(KKR) multiple scattering method. In practice, it is constructed from the regular and irregular solutions of the local Kohn-Sham equation and robust methods exist for spherical potentials. However, when applied to a non-spherical potential, numerical errors from the irregular solutions give rise to pathological behaviors of the charge density at small radius. Here we present a full-potential implementation of the fully-relativistic KKR method to perform ab initio self-consistent calculation by directly solving the Dirac differential equations using the generalized variable phase (sine and cosine matrices) formalism Liu et al. (2016). The pathology around the origin is completely eliminated by carrying out the energy integration of the single-site Green function along the real axis. By using an efficient pole-searching technique to identify the zeros of the well-behaved Jost matrices, we demonstrated that this scheme is numerically stable and computationally efficient, with speed comparable to the conventional contour energy integration method, while free of the pathology problem of the charge density. As an application, this method is utilized to investigate the crystal structures of polonium and their bulk properties, which is challenging for a conventional real-energy scheme. The noble metals are also calculated, both as a test of our method and to study the relativistic effects.
International Nuclear Information System (INIS)
Henk, J.
2004-01-01
Electron spectroscopy provides access to fundamental properties of solids, such as the geometric, electronic, and the magnetic structure. The latter are necessary for the understanding of a variety of basic but nevertheless important effects. The present work outlines recently developed theoretical approaches to electron spectroscopies. Most of the collected results rely on first-principles calculations, as formulated in multiple-scattering theory, and are contrasted with experimental findings. One topic involves spin- and angle-resolved photoelectron spectroscopy which is addressed for magnetic surfaces and ultrathin films. Exemplary results comprise magnetic dichroism in both valence-band and core-level photoemission as well as the temperature dependence of magnetic properties of ultrathin films. Another topic is spin-dependent ballistic transport through planar tunnel junctions, focusing here on the zero-bias anomaly. In most of the cases, spin-orbit coupling (SOC) is an essential ingredient and, hence, favors a relativistic description. Prominent effects of SOC are illustrated by means of the electronic structure of rare gases adsorbed on a substrate and by the splitting of surface states on Au(111). Concerning magnetism, the magnetic anisotropy of Ni films on Cu(001) is discussed, focusing in particular on the spin reorientation transition induced by lattice distortions in ultrathin films. (orig.)
Multiple Weather Factors Affect Apparent Survival of European Passerine Birds
Salewski, Volker; Hochachka, Wesley M.; Fiedler, Wolfgang
2013-01-01
Weather affects the demography of animals and thus climate change will cause local changes in demographic rates. In birds numerous studies have correlated demographic factors with weather but few of those examined variation in the impacts of weather in different seasons and, in the case of migrants, in different regions. Using capture-recapture models we correlated weather with apparent survival of seven passerine bird species with different migration strategies to assess the importance of selected facets of weather throughout the year on apparent survival. Contrary to our expectations weather experienced during the breeding season did not affect apparent survival of the target species. However, measures for winter severity were associated with apparent survival of a resident species, two short-distance/partial migrants and a long-distance migrant. Apparent survival of two short distance migrants as well as two long-distance migrants was further correlated with conditions experienced during the non-breeding season in Spain. Conditions in Africa had statistically significant but relatively minor effects on the apparent survival of the two long-distance migrants but also of a presumably short-distance migrant and a short-distance/partial migrant. In general several weather effects independently explained similar amounts of variation in apparent survival for the majority of species and single factors explained only relatively low amounts of temporal variation of apparent survival. Although the directions of the effects on apparent survival mostly met our expectations and there are clear predictions for effects of future climate we caution against simple extrapolations of present conditions to predict future population dynamics. Not only did weather explains limited amounts of variation in apparent survival, but future demographics will likely be affected by changing interspecific interactions, opposing effects of weather in different seasons, and the potential for
Love, Steven P.; Davis, Anthony B.; Rohde, Charles A.; Tellier, Larry; Ho, Cheng
2002-09-01
At most optical wavelengths, laser light in a cloud lidar experiment is not absorbed but merely scattered out of the beam, eventually escaping the cloud via multiple scattering. There is much information available in this light scattered far from the input beam, information ignored by traditional 'on-beam' lidar. Monitoring these off-beam returns in a fully space- and time-resolved manner is the essence of our unique instrument, Wide Angle Imaging Lidar (WAIL). In effect, WAIL produces wide-field (60-degree full-angle) 'movies' of the scattering process and records the cloud's radiative Green functions. A direct data product of WAIL is the distribution of photon path lengths resulting from multiple scattering in the cloud. Following insights from diffusion theory, we can use the measured Green functions to infer the physical thickness and optical depth of the cloud layer, and, from there, estimate the volume-averaged liquid water content. WAIL is notable in that it is applicable to optically thick clouds, a regime in which traditional lidar is reduced to ceilometry. Here we present recent WAIL data on various clouds and discuss the extension of WAIL to full diurnal monitoring by means of an ultra-narrow magneto-optic atomic line filter for daytime measurements.
International Nuclear Information System (INIS)
Love, Steven P.; Davis, Anthony B.; Rohde, Charles A.; Tellier, Larry L.; Ho, Cheng
2002-01-01
At most optical wavelengths, laser light in a cloud lidar experiment is not absorbed but merely scattered out of the beam, eventually escaping the cloud via multiple scattering. There is much information available in this light scattered far from the input beam, information ignored by traditional 'on-beam' lidar. Monitoring these off-beam returns in a fully space- and time-resolved manner is the essence of our unique instrument, Wide Angle Imaging Lidar (WAIL). In effect, WAIL produces wide-field (60-degree full-angle) 'movies' of the scattering process and records the cloud's radiative Green functions. A direct data product of WAIL is the distribution of photon path lengths resulting from multiple scattering in the cloud. Following insights from diffusion theory, we can use the measured Green functions to infer the physical thickness and optical depth of the cloud layer, and, from there, estimate the volume-averaged liquid water content. WAIL is notable in that it is applicable to optically thick clouds, a regime in which traditional lidar is reduced to ceilometry. Here we present recent WAIL data oti various clouds and discuss the extension of WAIL to full diurnal monitoring by means of an ultra-narrow magneto-optic atomic line filter for daytime measurements.
Bisphenol A affects androgen receptor function via multiple mechanisms.
Teng, Christina; Goodwin, Bonnie; Shockley, Keith; Xia, Menghang; Huang, Ruili; Norris, John; Merrick, B Alex; Jetten, Anton M; Austin, Christopher P; Tice, Raymond R
2013-05-25
Bisphenol A (BPA), is a well-known endocrine disruptor compound (EDC) that affects the normal development and function of the female and male reproductive system, however the mechanisms of action remain unclear. To investigate the molecular mechanisms of how BPA may affect ten different nuclear receptors, stable cell lines containing individual nuclear receptor ligand binding domain (LBD)-linked to the β-Gal reporter were examined by a quantitative high throughput screening (qHTS) format in the Tox21 Screening Program of the NIH. The results showed that two receptors, estrogen receptor alpha (ERα) and androgen receptor (AR), are affected by BPA in opposite direction. To confirm the observed effects of BPA on ERα and AR, we performed transient transfection experiments with full-length receptors and their corresponding response elements linked to luciferase reporters. We also included in this study two BPA analogs, bisphenol AF (BPAF) and bisphenol S (BPS). As seen in African green monkey kidney CV1 cells, the present study confirmed that BPA and BPAF act as ERα agonists (half maximal effective concentration EC50 of 10-100 nM) and as AR antagonists (half maximal inhibitory concentration IC50 of 1-2 μM). Both BPA and BPAF antagonized AR function via competitive inhibition of the action of synthetic androgen R1881. BPS with lower estrogenic activity (EC50 of 2.2 μM), did not compete with R1881 for AR binding, when tested at 30 μM. Finally, the effects of BPA were also evaluated in a nuclear translocation assays using EGPF-tagged receptors. Similar to 17β-estradiol (E2) which was used as control, BPA was able to enhance ERα nuclear foci formation but at a 100-fold higher concentration. Although BPA was able to bind AR, the nuclear translocation was reduced. Furthermore, BPA was unable to induce functional foci in the nuclei and is consistent with the transient transfection study that BPA is unable to activate AR. Published by Elsevier Ireland Ltd.
Multiple Scattering Principal Component-based Radiative Transfer Model (PCRTM) from Far IR to UV-Vis
Liu, X.; Wu, W.; Yang, Q.
2017-12-01
Modern satellite hyperspectral satellite remote sensors such as AIRS, CrIS, IASI, CLARREO all require accurate and fast radiative transfer models that can deal with multiple scattering of clouds and aerosols to explore the information contents. However, performing full radiative transfer calculations using multiple stream methods such as discrete ordinate (DISORT), doubling and adding (AD), successive order of scattering order of scattering (SOS) are very time consuming. We have developed a principal component-based radiative transfer model (PCRTM) to reduce the computational burden by orders of magnitudes while maintain high accuracy. By exploring spectral correlations, the PCRTM reduce the number of radiative transfer calculations in frequency domain. It further uses a hybrid stream method to decrease the number of calls to the computational expensive multiple scattering calculations with high stream numbers. Other fast parameterizations have been used in the infrared spectral region reduce the computational time to milliseconds for an AIRS forward simulation (2378 spectral channels). The PCRTM has been development to cover spectral range from far IR to UV-Vis. The PCRTM model have been be used for satellite data inversions, proxy data generation, inter-satellite calibrations, spectral fingerprinting, and climate OSSE. We will show examples of applying the PCRTM to single field of view cloudy retrievals of atmospheric temperature, moisture, traces gases, clouds, and surface parameters. We will also show how the PCRTM are used for the NASA CLARREO project.
Multiple Breed Validation of Five QTL Affecting Mastitis Resistance
DEFF Research Database (Denmark)
Vilkki, Johanna; Dolezal, Marlies A; Sahana, Goutam
Ayrshire (SCC, clinical mastitis, udder conformation) and Valdostana (SCC, milk bacteriological results). Furthermore, association analysis across the regions was performed with a linear mixed model using imputed sequence for 845 Danish Red sires with nine mastitis phenotypes. Associations in five regions......Mastitis is a major animal welfare problem and the most costly disease in dairy cattle worldwide. Within the EU FP7 Quantomics project, we aimed at validating quantitative trait loci affecting mastitis resistance at the molecular level. Eight chromosome regions with major effects on resistance...... to mastitis were identified by GWAS using high-density SNP array in the Finnish Ayrshire and Brown Swiss breeds. These targeted regions were analyzed for polymorphisms from 20X whole-genome sequences of 38 ancestral bulls of the two populations. A set of 384 SNPs were selected based on their ranking from...
A hybrid approach to simulate multiple photon scattering in X-ray imaging
International Nuclear Information System (INIS)
Freud, N.; Letang, J.-M.; Babot, D.
2005-01-01
A hybrid simulation approach is proposed to compute the contribution of scattered radiation in X- or γ-ray imaging. This approach takes advantage of the complementarity between the deterministic and probabilistic simulation methods. The proposed hybrid method consists of two stages. Firstly, a set of scattering events occurring in the inspected object is determined by means of classical Monte Carlo simulation. Secondly, this set of scattering events is used as a starting point to compute the energy imparted to the detector, with a deterministic algorithm based on a 'forced detection' scheme. For each scattering event, the probability for the scattered photon to reach each pixel of the detector is calculated using well-known physical models (form factor and incoherent scattering function approximations, in the case of Rayleigh and Compton scattering respectively). The results of the proposed hybrid approach are compared to those obtained with the Monte Carlo method alone (Geant4 code) and found to be in excellent agreement. The convergence of the results when the number of scattering events increases is studied. The proposed hybrid approach makes it possible to simulate the contribution of each type (Compton or Rayleigh) and order of scattering, separately or together, with a single PC, within reasonable computation times (from minutes to hours, depending on the number of pixels of the detector). This constitutes a substantial benefit, compared to classical simulation methods (Monte Carlo or deterministic approaches), which usually requires a parallel computing architecture to obtain comparable results
A hybrid approach to simulate multiple photon scattering in X-ray imaging
Energy Technology Data Exchange (ETDEWEB)
Freud, N. [CNDRI, Laboratory of Nondestructive Testing using Ionizing Radiations, INSA-Lyon Scientific and Technical University, Bat. Antoine de Saint-Exupery, 20, avenue Albert Einstein, 69621 Villeurbanne Cedex (France)]. E-mail: nicolas.freud@insa-lyon.fr; Letang, J.-M. [CNDRI, Laboratory of Nondestructive Testing using Ionizing Radiations, INSA-Lyon Scientific and Technical University, Bat. Antoine de Saint-Exupery, 20, avenue Albert Einstein, 69621 Villeurbanne Cedex (France); Babot, D. [CNDRI, Laboratory of Nondestructive Testing using Ionizing Radiations, INSA-Lyon Scientific and Technical University, Bat. Antoine de Saint-Exupery, 20, avenue Albert Einstein, 69621 Villeurbanne Cedex (France)
2005-01-01
A hybrid simulation approach is proposed to compute the contribution of scattered radiation in X- or {gamma}-ray imaging. This approach takes advantage of the complementarity between the deterministic and probabilistic simulation methods. The proposed hybrid method consists of two stages. Firstly, a set of scattering events occurring in the inspected object is determined by means of classical Monte Carlo simulation. Secondly, this set of scattering events is used as a starting point to compute the energy imparted to the detector, with a deterministic algorithm based on a 'forced detection' scheme. For each scattering event, the probability for the scattered photon to reach each pixel of the detector is calculated using well-known physical models (form factor and incoherent scattering function approximations, in the case of Rayleigh and Compton scattering respectively). The results of the proposed hybrid approach are compared to those obtained with the Monte Carlo method alone (Geant4 code) and found to be in excellent agreement. The convergence of the results when the number of scattering events increases is studied. The proposed hybrid approach makes it possible to simulate the contribution of each type (Compton or Rayleigh) and order of scattering, separately or together, with a single PC, within reasonable computation times (from minutes to hours, depending on the number of pixels of the detector). This constitutes a substantial benefit, compared to classical simulation methods (Monte Carlo or deterministic approaches), which usually requires a parallel computing architecture to obtain comparable results.
Directory of Open Access Journals (Sweden)
Gouveia Diego
2018-01-01
Full Text Available Lidar measurements of cirrus clouds are highly influenced by multiple scattering (MS. We therefore developed an iterative approach to correct elastic backscatter lidar signals for multiple scattering to obtain best estimates of single-scattering cloud optical depth and lidar ratio as well as of the ice crystal effective radius. The approach is based on the exploration of the effect of MS on the molecular backscatter signal returned from above cloud top.
Gouveia, Diego; Baars, Holger; Seifert, Patric; Wandinger, Ulla; Barbosa, Henrique; Barja, Boris; Artaxo, Paulo; Lopes, Fabio; Landulfo, Eduardo; Ansmann, Albert
2018-04-01
Lidar measurements of cirrus clouds are highly influenced by multiple scattering (MS). We therefore developed an iterative approach to correct elastic backscatter lidar signals for multiple scattering to obtain best estimates of single-scattering cloud optical depth and lidar ratio as well as of the ice crystal effective radius. The approach is based on the exploration of the effect of MS on the molecular backscatter signal returned from above cloud top.
Amino Acid Catabolism in Multiple Sclerosis Affects Immune Homeostasis.
Negrotto, Laura; Correale, Jorge
2017-03-01
Amino acid catabolism has been implicated in immunoregulatory mechanisms present in several diseases, including autoimmune disorders. Our aims were to assess expression and activity of enzymes involved in Trp and Arg catabolism, as well as to investigate amino acid catabolism effects on the immune system of multiple sclerosis (MS) patients. To this end, 40 MS patients, 30 healthy control subjects, and 30 patients with other inflammatory neurological diseases were studied. Expression and activity of enzymes involved in Trp and Arg catabolism (IDO1, IDO2, Trp 2,3-dioxygenase [TDO], arginase [ARG] 1, ARG2, inducible NO synthetase) were evaluated in PBMCs. Expression of general control nonrepressed 2 serine/threonine kinase and mammalian target of rapamycin (both molecules involved in sensing amino acid levels) was assessed in response to different stimuli modulating amino acid catabolism, as were cytokine secretion levels and regulatory T cell numbers. The results demonstrate that expression and activity of IDO1 and ARG1 were significantly reduced in MS patients compared with healthy control subjects and other inflammatory neurological diseases. PBMCs from MS patients stimulated with a TLR-9 agonist showed reduced expression of general control nonrepressed 2 serine/threonine kinase and increased expression of mammalian target of rapamycin, suggesting reduced amino acid catabolism in MS patients. Functionally, this reduction resulted in a decrease in regulatory T cells, with an increase in myelin basic protein-specific T cell proliferation and secretion of proinflammatory cytokines. In contrast, induction of IDO1 using CTLA-4 or a TLR-3 ligand dampened proinflammatory responses. Overall, these results highlight the importance of amino acid catabolism in the modulation of the immunological responses in MS patients. Molecules involved in these pathways warrant further exploration as potential new therapeutic targets in MS. Copyright © 2017 by The American Association of
Multiple controls affect arsenite oxidase gene expression in Herminiimonas arsenicoxydans
Directory of Open Access Journals (Sweden)
Coppée Jean-Yves
2010-02-01
Full Text Available Abstract Background Both the speciation and toxicity of arsenic are affected by bacterial transformations, i.e. oxidation, reduction or methylation. These transformations have a major impact on environmental contamination and more particularly on arsenic contamination of drinking water. Herminiimonas arsenicoxydans has been isolated from an arsenic- contaminated environment and has developed various mechanisms for coping with arsenic, including the oxidation of As(III to As(V as a detoxification mechanism. Results In the present study, a differential transcriptome analysis was used to identify genes, including arsenite oxidase encoding genes, involved in the response of H. arsenicoxydans to As(III. To get insight into the molecular mechanisms of this enzyme activity, a Tn5 transposon mutagenesis was performed. Transposon insertions resulting in a lack of arsenite oxidase activity disrupted aoxR and aoxS genes, showing that the aox operon transcription is regulated by the AoxRS two-component system. Remarkably, transposon insertions were also identified in rpoN coding for the alternative N sigma factor (σ54 of RNA polymerase and in dnaJ coding for the Hsp70 co-chaperone. Western blotting with anti-AoxB antibodies and quantitative RT-PCR experiments allowed us to demonstrate that the rpoN and dnaJ gene products are involved in the control of arsenite oxidase gene expression. Finally, the transcriptional start site of the aoxAB operon was determined using rapid amplification of cDNA ends (RACE and a putative -12/-24 σ54-dependent promoter motif was identified upstream of aoxAB coding sequences. Conclusion These results reveal the existence of novel molecular regulatory processes governing arsenite oxidase expression in H. arsenicoxydans. These data are summarized in a model that functionally integrates arsenite oxidation in the adaptive response to As(III in this microorganism.
Tedgren, Åsa Carlsson; Plamondon, Mathieu; Beaulieu, Luc
2015-07-07
The aim of this work was to investigate how dose distributions calculated with the collapsed cone (CC) algorithm depend on the size of the water phantom used in deriving the point kernel for multiple scatter. A research version of the CC algorithm equipped with a set of selectable point kernels for multiple-scatter dose that had initially been derived in water phantoms of various dimensions was used. The new point kernels were generated using EGSnrc in spherical water phantoms of radii 5 cm, 7.5 cm, 10 cm, 15 cm, 20 cm, 30 cm and 50 cm. Dose distributions derived with CC in water phantoms of different dimensions and in a CT-based clinical breast geometry were compared to Monte Carlo (MC) simulations using the Geant4-based brachytherapy specific MC code Algebra. Agreement with MC within 1% was obtained when the dimensions of the phantom used to derive the multiple-scatter kernel were similar to those of the calculation phantom. Doses are overestimated at phantom edges when kernels are derived in larger phantoms and underestimated when derived in smaller phantoms (by around 2% to 7% depending on distance from source and phantom dimensions). CC agrees well with MC in the high dose region of a breast implant and is superior to TG43 in determining skin doses for all multiple-scatter point kernel sizes. Increased agreement between CC and MC is achieved when the point kernel is comparable to breast dimensions. The investigated approximation in multiple scatter dose depends on the choice of point kernel in relation to phantom size and yields a significant fraction of the total dose only at distances of several centimeters from a source/implant which correspond to volumes of low doses. The current implementation of the CC algorithm utilizes a point kernel derived in a comparatively large (radius 20 cm) water phantom. A fixed point kernel leads to predictable behaviour of the algorithm with the worst case being a source/implant located well within a patient
How a change in the interaction potential affects the p-wave scattering volume
International Nuclear Information System (INIS)
Jamieson, M J; Dalgarno, A
2012-01-01
We derive a simple expression for the change in the s-wave scattering length in terms of zero-energy wavefunctions, we generalize it to obtain an expression for the change in the p-wave scattering volume and we use both expressions to derive the first order differential equations of variable phase theory that are satisfied by the closely related accumulated scattering length and volume. We provide numerical demonstrations for the example of a pair of hydrogen atoms interacting via the X 1 Σ + g molecular state. (fast track communication)
Energy Technology Data Exchange (ETDEWEB)
Malhotra, M. [Stanford Univ., CA (United States)
1996-12-31
Finite-element discretizations of time-harmonic acoustic wave problems in exterior domains result in large sparse systems of linear equations with complex symmetric coefficient matrices. In many situations, these matrix problems need to be solved repeatedly for different right-hand sides, but with the same coefficient matrix. For instance, multiple right-hand sides arise in radiation problems due to multiple load cases, and also in scattering problems when multiple angles of incidence of an incoming plane wave need to be considered. In this talk, we discuss the iterative solution of multiple linear systems arising in radiation and scattering problems in structural acoustics by means of a complex symmetric variant of the BL-QMR method. First, we summarize the governing partial differential equations for time-harmonic structural acoustics, the finite-element discretization of these equations, and the resulting complex symmetric matrix problem. Next, we sketch the special version of BL-QMR method that exploits complex symmetry, and we describe the preconditioners we have used in conjunction with BL-QMR. Finally, we report some typical results of our extensive numerical tests to illustrate the typical convergence behavior of BL-QMR method for multiple radiation and scattering problems in structural acoustics, to identify appropriate preconditioners for these problems, and to demonstrate the importance of deflation in block Krylov-subspace methods. Our numerical results show that the multiple systems arising in structural acoustics can be solved very efficiently with the preconditioned BL-QMR method. In fact, for multiple systems with up to 40 and more different right-hand sides we get consistent and significant speed-ups over solving the systems individually.
Finan, Patrick H; Quartana, Phillip J; Remeniuk, Bethany; Garland, Eric L; Rhudy, Jamie L; Hand, Matthew; Irwin, Michael R; Smith, Michael T
2017-01-01
Ample behavioral and neurobiological evidence links sleep and affective functioning. Recent self-report evidence suggests that the affective problems associated with sleep loss may be stronger for positive versus negative affective state and that those effects may be mediated by changes in electroencepholographically measured slow wave sleep (SWS). In the present study, we extend those preliminary findings using multiple measures of affective functioning. In a within-subject randomized crossover experiment, we tested the effects of one night of sleep continuity disruption via forced awakenings (FA) compared to one night of uninterrupted sleep (US) on three measures of positive and negative affective functioning: self-reported affective state, affective pain modulation, and affect-biased attention. The study was set in an inpatient clinical research suite. Healthy, good sleeping adults (N = 45) were included. Results indicated that a single night of sleep continuity disruption attenuated positive affective state via FA-induced reductions in SWS. Additionally, sleep continuity disruption attenuated the inhibition of pain by positive affect as well as attention bias to positive affective stimuli. Negative affective state, negative affective pain facilitation, nor negative attention bias were altered by sleep continuity disruption. The present findings, observed across multiple measures of affective function, suggest that sleep continuity disruption has a stronger influence on the positive affective system relative to the negative affective affective system. © Sleep Research Society 2016. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.
International Nuclear Information System (INIS)
Li, Z.J.; Wu, Z.S.; Qu, T.; Shang, Q.C.; Bai, L.
2016-01-01
Based on the generalized multiparticle Mie theory, multiple scattering of an aggregate of uniaxial anisotropic spheres illuminated by a zero-order Bessel beam (ZOBB) with arbitrary propagation direction is investigated. The particle size and configuration are arbitrary. The arbitrary incident Bessel beam is expanded in terms of spherical vector wave functions (SVWFs). Utilizing the vector addition theorem of SVWFs, interactive and total scattering coefficients are derived through the continuous boundary conditions on which the interaction of the particles is considered. The accuracy of the theory and codes are verified by comparing results with those obtained for arbitrary plane wave incidence by CST simulation, and for ZOBB incidence by a numerical method. The effects of angle of incidence, pseudo-polarization angle, half-conical angle, beam center position, and permittivity tensor elements on the radar cross sections (RCSs) of several types of collective uniaxial anisotropic spheres, such as a linear chain, a 4×4×4 cube-shaped array, and other periodical structures consisting of massive spheres, are numerically analyzed. Selected results on the properties of typical particles such as TiO 2 , SiO 2 , or other particle lattices are calculated. This investigation could provide an effective test for further research on the scattering characteristics of an aggregate of anisotropic spheres by a high-order Bessel vortex beam. The results have important application in optical tweezers and particle manipulation. - Highlights: • Scattering of Bessel beam by an aggregate of uniaxial anisotropic spheres is studied. • The zero-order Bessel beam propagates and polarizes along arbitrary direction. • The accuracy of expansion coefficients, the scattering theory and codes is verified. • Effects of various parameters on scattering properties are numerically discussed. • Scattering properties of several type of periodical array are numerically analyzed.
International Nuclear Information System (INIS)
Mayer, M.; Arstila, K.; Nordlund, K.; Edelmann, E.; Keinonen, J.
2006-01-01
Angular and energy distributions due to multiple small angle scattering were calculated with different models, namely from the analytical Szilagyi theory, the Monte-Carlo code MCERD in binary collision approximation and the molecular dynamics code MDRANGE, for 2 MeV 4 He in Au at backscattering geometry and for 20 MeV 127 I recoil analysis of carbon. The widths and detailed shapes of the distributions are compared, and reasons for deviations between the different models are discussed
Schuengel, C; Sterkenburg, P S; Jeczynski, P; Janssen, C G C; Jongbloed, G
2009-01-01
: In a controlled multiple case design study, the development of a therapeutic relationship and its role in affect regulation were studied in 6 children with visual disabilities, severe intellectual disabilities, severe challenging behavior, and prolonged social deprivation. In the 1st phase,
A Path Loss Model for Non-Line-of-Sight Ultraviolet Multiple Scattering Channels
2010-01-01
scattering is self -governed, and the distances and angles for different scattering events are conditioned on previous quantities. Therefore, the arrival...solid angle of the receiver determined by the receiver area and distance rn. Note that no integration over rn is needed because it is a function of...www.eurasip.org). This year edition will take place in Barcelona, capital city of Catalonia (Spain), and will be jointly organized by the Centre Tecnològic de
Light focusing through a multiple scattering medium: ab initio computer simulation
Danko, Oleksandr; Danko, Volodymyr; Kovalenko, Andrey
2018-01-01
The present study considers ab initio computer simulation of the light focusing through a complex scattering medium. The focusing is performed by shaping the incident light beam in order to obtain a small focused spot on the opposite side of the scattering layer. MSTM software (Auburn University) is used to simulate the propagation of an arbitrary monochromatic Gaussian beam and obtain 2D distribution of the optical field in the selected plane of the investigated volume. Based on the set of incident and scattered fields, the pair of right and left eigen bases and corresponding singular values were calculated. The pair of right and left eigen modes together with the corresponding singular value constitute the transmittance eigen channel of the disordered media. Thus, the scattering process is described in three steps: 1) initial field decomposition in the right eigen basis; 2) scaling of decomposition coefficients for the corresponding singular values; 3) assembling of the scattered field as the composition of the weighted left eigen modes. Basis fields are represented as a linear combination of the original Gaussian beams and scattered fields. It was demonstrated that 60 independent control channels provide focusing the light into a spot with the minimal radius of approximately 0.4 μm at half maximum. The intensity enhancement in the focal plane was equal to 68 that coincided with theoretical prediction.
A Path Loss Model for Non-Line-of-Sight Ultraviolet Multiple Scattering Channels
Directory of Open Access Journals (Sweden)
Sadler BrianM
2010-01-01
Full Text Available An ultraviolet (UV signal transmission undergoes rich scattering and strong absorption by atmospheric particulates. We develop a path loss model for a Non-Line-of-Sight (NLOS link. The model is built upon probability theory governing random migration of photons in free space, undergoing scattering, in terms of angular direction and distance. The model analytically captures the contributions of different scattering orders. Thus it relaxes the assumptions of single scattering theory and provides more realistic results. This allows us to assess the importance of high-order scattering, such as in a thick atmosphere environment, where short range NLOS UV communication is enhanced by hazy or foggy weather. By simulation, it is shown that the model coincides with a previously developed Monte Carlo model. Additional numerical examples are presented to demonstrate the effects of link geometry and atmospheric conditions. The results indicate the inherent tradeoffs in beamwidth, pointing angles, range, absorption, and scattering and so are valuable for NLOS communication system design.
Whole Genome Scan to Detect Chromosomal Regions Affecting Multiple Traits in Dairy Cattle
Schrooten, C.; Bink, M.C.A.M.; Bovenhuis, H.
2004-01-01
Chromosomal regions affecting multiple traits ( multiple trait quantitative trait regions or MQR) in dairy cattle were detected using a method based on results from single trait analyses to detect quantitative trait loci (QTL). The covariance between contrasts for different traits in single trait
Schäfer, Sascha; Liang, Wenxi; Zewail, Ahmed H
2011-12-07
Recent studies in ultrafast electron crystallography (UEC) using a reflection diffraction geometry have enabled the investigation of a wide range of phenomena on the femtosecond and picosecond time scales. In all these studies, the analysis of the diffraction patterns and their temporal change after excitation was performed within the kinematical scattering theory. In this contribution, we address the question, to what extent dynamical scattering effects have to be included in order to obtain quantitative information about structural dynamics. We discuss different scattering regimes and provide diffraction maps that describe all essential features of scatterings and observables. The effects are quantified by dynamical scattering simulations and examined by direct comparison to the results of ultrafast electron diffraction experiments on an in situ prepared Ni(100) surface, for which structural dynamics can be well described by a two-temperature model. We also report calculations for graphite surfaces. The theoretical framework provided here allows for further UEC studies of surfaces especially at larger penetration depths and for those of heavy-atom materials. © 2011 American Institute of Physics
Quantum multiple scattering: Eigenmode expansion and its applications to proximity resonance
International Nuclear Information System (INIS)
Li Sheng; Heller, Eric J.
2003-01-01
We show that for a general system of N s-wave point scatterers, there are always N eigenmodes. These eigenmodes or eigenchannels play the same role as spherical harmonics for a spherically symmetric target--they give a phase shift only. In other words, the T matrix of the system is of rank N, and the eigenmodes are eigenvectors corresponding to nonzero eigenvalues of the T matrix. The eigenmode expansion approach can give insight to the total scattering cross section; the position, width, and superradiant or subradiant nature of resonance peaks; the unsymmetric Fano line shape of sharp proximity resonance peaks based on the high-energy tail of a broadband; and other properties. Off-resonant eigenmodes for identical proximate scatterers are approximately angular-momentum eigenstates
Analysis of pp scattering at the CERN ISR energies in the multiple Regge pole model
International Nuclear Information System (INIS)
Bugrij, A.I.; Kobylinsky, N.A.
1976-01-01
The simple Regge model is suggested for describing data on proton-proton elastic scattering at high energies. The simplest variant of the Regge model can be formulated as a sum of two pomerons, the first being a moving double pole and the second - a fixed simple pole. Comparison with known data is given. The model gives an infinite rise of the total cross section of pp-scattering. The differential cross section changes slowly with energy. The models of two pomerons reproduce many features of the geometric scaling, in particular, the shift of the dip and rise of scattering total cross section at the second maximum. The considered model is rather simple and is well consistent with experiment
Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood
2005-01-01
Effects of multiple scattering on reflectivity are studied for millimeter wavelength weather radars. A time-independent vector theory, including up to second-order scattering, is derived for a single layer of hydrometeors of a uniform density and a uniform diameter. In this theory, spherical waves with a Gaussian antenna pattern are used to calculate ladder and cross terms in the analytical scattering theory. The former terms represent the conventional multiple scattering, while the latter terms cause backscattering enhancement in both the copolarized and cross-polarized components. As the optical thickness of the hydrometeor layer increases, the differences from the conventional plane wave theory become more significant, and essentially, the reflectivity of multiple scattering depends on the ratio of mean free path to radar footprint radius. These results must be taken into account when analyzing radar reflectivity for use in remote sensing.
Solving protein nanocrystals by cryo-EM diffraction: Multiple scattering artifacts
Energy Technology Data Exchange (ETDEWEB)
Subramanian, Ganesh [Department of Materials Science and Engineering, Arizona State University, Tempe, AZ (United States); Basu, Shibom [Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ (United States); Liu, Haiguang [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States); Zuo, Jian-Min [Department of Materials Science and Engineering, University of Illinois, Urbana, IL (United States); Spence, John C.H., E-mail: spence@asu.edu [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States)
2015-01-15
The maximum thickness permissible within the single-scattering approximation for the determination of the structure of perfectly ordered protein microcrystals by transmission electron diffraction is estimated for tetragonal hen-egg lysozyme protein crystals using several approaches. Multislice simulations are performed for many diffraction conditions and beam energies to determine the validity domain of the required single-scattering approximation and hence the limit on crystal thickness. The effects of erroneous experimental structure factor amplitudes on the charge density map for lysozyme are noted and their threshold limits calculated. The maximum thickness of lysozyme permissible under the single-scattering approximation is also estimated using R-factor analysis. Successful reconstruction of density maps is found to result mainly from the use of the phase information provided by modeling based on the protein data base through molecular replacement (MR), which dominates the effect of poor quality electron diffraction data at thicknesses larger than about 200 Å. For perfectly ordered protein nanocrystals, a maximum thickness of about 1000 Å is predicted at 200 keV if MR can be used, using R-factor analysis performed over a subset of the simulated diffracted beams. The effects of crystal bending, mosaicity (which has recently been directly imaged by cryo-EM) and secondary scattering are discussed. Structure-independent tests for single-scattering and new microfluidic methods for growing and sorting nanocrystals by size are reviewed. - Highlights: • Validity domain of single-scattering approximation for protein electron diffraction is assessed • Electron Diffraction for tetragonal hen-egg lysozyme is simulated using multislice. • Bias from the use of phase information in modeling by molecular replacement (MR) is evaluated. • We find an approximate upper thickness limit, if MR is used, of 100 nm. • A 35% error in structure factor magnitudes may be
Comparison of approximate methods for multiple scattering in high-energy collisions. II
International Nuclear Information System (INIS)
Nolan, A.M.; Tobocman, W.; Werby, M.F.
1976-01-01
The scattering in one dimension of a particle by a target of N like particles in a bound state has been studied. The exact result for the transmission probability has been compared with the predictions of the Glauber theory, the Watson optical potential model, and the adiabatic (or fixed scatterer) approximation. The approximate methods optical potential model is second best. The Watson method is found to work better when the kinematics suggested by Foldy and Walecka are used rather than that suggested by Watson, that is to say, when the two-body of the nucleon-nucleon reduced mass
Voit, Florian; Schäfer, Jan; Kienle, Alwin
2009-09-01
We present a methodology to compare results of classical radiative transfer theory against exact solutions of Maxwell theory for a high number of spheres. We calculated light propagation in a cubic scattering region (20 x 20 x 20 microm(3)) consisting of different concentrations of polystyrene spheres in water (diameter 2 microm) by an analytical solution of Maxwell theory and by a numerical solution of radiative transfer theory. The relative deviation of differential as well as total scattering cross sections obtained by both approaches was evaluated for each sphere concentration. For the considered case, we found that deviations due to radiative transfer theory remain small, even for concentrations up to ca. 20 vol. %.
Multiple refraction switches realized by stretching elastomeric scatterers in sonic crystals
Directory of Open Access Journals (Sweden)
Y. Huang
2015-02-01
Full Text Available The effect of out-of-plane pre-stretch on the 2D sonic crystal with stretchable elastomeric scatterers is explored. The hyperelastic scatterers are characterized by a compressible neo-Hookean model. The Dirichlet-to-Neumann (DtN map is adopted to obtain the band structure and equi-frequency contours. We focus on the first passband and find that a variety of switching functionalities for refraction behaviors can be realized in selected frequencies under a specific pre-stretch range. These refraction switches enable an active control of wave propagation and are applicable in advanced technologies where switchable and multifunctional sonic crystals are required.
Energy Technology Data Exchange (ETDEWEB)
Airapetian, A. [Giessen Univ. (Germany). Physikalisches Inst.; Michigan Univ., Ann Arbor, MI (United States). Randall Lab. of Physics; Akopov, N. [Yerevan Physics Institute (Armenia); Akopov, Z. [DESY Hamburg (Germany)] [and others; Collaboration: HERMES Collaboration
2012-12-15
Multiplicities in semi-inclusive deep-inelastic scattering are presented for each charge state of {pi}{sup {+-}} and K{sup {+-}} mesons. The data were collected by the HERMES experiment at the HERA storage ring using 27.6 GeV electron and positron beams incident on a hydrogen or deuterium gas target. The results are presented as a function of the kinematic quantities x{sub B}, Q{sup 2}, z, and P{sub h} {sub perpendicular} {sub to}. They represent a unique data set for identified hadrons that will significantly enhance our understanding of the fragmentation of quarks into final-state hadrons in deep-inelastic scattering.
Czech Academy of Sciences Publication Activity Database
Woo, W.; Em, V.; Shin, E.; Mikula, Pavol; Ryukhtin, Vasyl
2015-01-01
Roč. 48, APR (2015), s. 350-356 ISSN 0021-8898 R&D Projects: GA ČR GB14-36566G; GA MŠk(CZ) LM2011019 Institutional support: RVO:61389005 Keywords : peak broadening * small-angle neutron scattering * neutron diffraction * magnetic domain Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.720, year: 2014
Penttilä, Antti; Väisänen, Timo; Markkanen, Johannes; Martikainen, Julia; Gritsevich, Maria; Muinonen, Karri
2017-10-01
We combine numerical tools to analyze the reflectance spectra of granular materials. Our motivation comes from the lack of tools when it comes to intimate mixing of materials and modeling space-weathering effects with nano- or micron-sized inclusions. The current practice is to apply a semi-physical models such as the Hapke models (e.g., Icarus 195, 2008). These are expressed in a closed form so that they are fast to apply. The problem is that the validity of the model is not guaranteed, and the derived properties related to particle scattering can be unrealistic (JQSRT 113, 2012).Our pipeline consists of individual scattering simulation codes and a main program that chains them together. The chain for analyzing a macroscopic target with space-weathered mineral would go as: (1) Scattering properties of small inclusions inside a host matrix are derived using exact Maxwell equation solvers. From the scattering properties, we use the so-called incoherent fields and Mueller matrices as input for the next step; (2) Scattering by a regolith grain is solved using a geometrical optics method with surface reflections, internal absorption, and internal diffuse scattering; (3) The radiative transfer simulation is executed inputting the regolith grains from the previous step as the scatterers in a macroscopic planar volume element.For the most realistic asteroid reflectance model, the chain would produce the properties of a planar surface element. Then, a shadowing simulation over the surface elements would be considered, and finally the asteroid phase function would be solved by integrating the bidirectional reflectance distribution function of the planar element over the object's realistic shape model.The tools in the proposed chain already exist, and practical task for us is to tie these together into an easy-to-use public pipeline. We plan to open the pipeline as a web-based open service a dedicated server, using Django application server and Python environment for the
Energy Technology Data Exchange (ETDEWEB)
Resel, Roland, E-mail: roland.resel@tugraz.at; Bainschab, Markus; Pichler, Alexander [Graz University of Technology, Graz (Austria); Dingemans, Theo [Delft University of Technology, Delft (Netherlands); Simbrunner, Clemens [Johannes Kepler University, Linz (Austria); University of Bremen, Bremen (Germany); Stangl, Julian [Johannes Kepler University, Linz (Austria); Salzmann, Ingo [Humboldt University, Berlin (Germany)
2016-04-20
The use of grazing-incidence X-ray diffraction to determine the crystal structure from thin films requires accurate positions of Bragg peaks. Refraction effects and multiple scattering events have to be corrected or minimized. Dynamical scattering effects are observed in grazing-incidence X-ray diffraction experiments using an organic thin film of 2,2′:6′,2′′-ternaphthalene grown on oxidized silicon as substrate. Here, a splitting of all Bragg peaks in the out-of-plane direction (z-direction) has been observed, the magnitude of which depends both on the incidence angle of the primary beam and the out-of-plane angle of the scattered beam. The incident angle was varied between 0.09° and 0.25° for synchrotron radiation of 10.5 keV. This study reveals comparable intensities of the split peaks with a maximum for incidence angles close to the critical angle of total external reflection of the substrate. This observation is rationalized by two different scattering pathways resulting in diffraction peaks at different positions at the detector. In order to minimize the splitting, the data suggest either using incident angles well below the critical angle of total reflection or angles well above, which sufficiently attenuates the contributions from the second scattering path. This study highlights that the refraction of X-rays in (organic) thin films has to be corrected accordingly to allow for the determination of peak positions with sufficient accuracy. Based thereon, a reliable determination of the lattice constants becomes feasible, which is required for crystallographic structure solutions from thin films.
Group Positive Psychotherapy and Depression of Females Affected by Multiple Sclerosis
Directory of Open Access Journals (Sweden)
Tayebeh Khayatan
2014-12-01
Full Text Available Objectives: Multiple Sclerosis is one of the most important and prevalent central nervous system diseases, causing disorders such as depression among affected patients. Positive psychotherapy is also a new approach that can be effective in reducing the depression of these people. This study aims to investigate the efficiency of group positive psychotherapy for decreasing the depression among females affected by Multiple Sclerosis. Methods: A samples of 30 females affected by Multiple Sclerosis with mild to moderate depression were participated, and were divided into two groups, intervention and control. Both groups completed Beck Depression Inventory II (BDI-II at the beginning, he intervention group received six sessions of positive psychotherapy. After the intervention both group completed the questionnaire again. Data was analyzed by descriptive and inferential statistical methods. Results: The result demonstrated that, the decline of depression was more in the intervention group than the control group. Moreover in the intervention group than control group, there was obtained significant reduction in both sub-scales of Beck Depression Inventory II. Discussion: Results of this study indicated that group positive psychotherapy is effective in reducing the depression of females affected by Multiple Sclerosis. This treatment can be widely used in the caring centers for treatment of people affected by Multiple Sclerosis and this can be justified because of its low cost and good efficiency.
DEFF Research Database (Denmark)
Toft-Petersen, Rasmus; Groitl, Felix; Kure, Mathias
2016-01-01
A thorough experimental characterization of a multiplexing backend with multiple energy analysis on a cold-neutron triple axis spectrometer (cTAS) is presented. The prototype employs two angular segments (2 theta-segments) each containing five vertically scattering analyzers (energy channels...... to the energy resolution of a standard cTAS. The dispersion relation of the antiferromagnetic excitations in MnF2 has been mapped out by performing constant energy transfer maps. These results show that the tested setup is virtually spurion free. In addition, focusing effects due to (mis...
Gong, Z; Hu, R H; Shou, Y R; Qiao, B; Chen, C E; He, X T; Bulanov, S S; Esirkepov, T Zh; Bulanov, S V; Yan, X Q
2017-01-01
γ-ray flash generation in near-critical-density target irradiated by four symmetrical colliding laser pulses is numerically investigated. With peak intensities about 10^{23} W/cm^{2}, the laser pulses boost electron energy through direct laser acceleration, while pushing them inward with the ponderomotive force. After backscattering with counterpropagating laser, the accelerated electron is trapped in the electromagnetic standing waves or the ponderomotive potential well created by the coherent overlapping of the laser pulses, and emits γ-ray photons in a multiple-laser-scattering regime, where electrons act as a medium transferring energy from the laser to γ rays in the ponderomotive potential valley.
International Nuclear Information System (INIS)
Gagnon, J.S.; Fillion-Gourdeau, F.; Sangyong Jeong; RIKEN Research Center, Upton, NY
2006-01-01
We use the full multiple scattering expansion of the retarded self-energy to obtain the gain and loss rates present in the Kadanoff-Baym relativistic transport equation. The rates we obtain include processes with any number of particles. As a first approximation, we only consider central cuts in the self-energies, but otherwise our results are general. We specialize to the case of scalar field theory to compare with lowest order results. The main application of this work is relativistic transport theory of very dense systems, such as the quark-gluon plasma or the early universe, where multi-particle interactions are important. (author)
Wang, Kezhi; Wang, Tian; Chen, Yunfei; Alouini, Mohamed-Slim
2014-01-01
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.
Wang, Kezhi
2014-09-01
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.
Revisit the spin-FET: Multiple reflection, inelastic scattering, and lateral size effects
Xu, Luting; Li, Xin-Qi; Sun, Qing-feng
2014-01-01
We revisit the spin-injected field effect transistor (spin-FET) by simulating a lattice model based on recursive lattice Green's function approach. In the one-dimensional case and coherent regime, the simulated results reveal noticeable differences from the celebrated Datta-Das model, which motivate thus an improved treatment and lead to analytic and generalized result. The simulation also allows us to address inelastic scattering (using B\\"uttiker's fictitious reservoir approach) and lateral...
International Nuclear Information System (INIS)
Torrini, M.
1983-01-01
The exponential nature of the translation matrix G of spherical free waves has been set forth in a previous paper.The explicit expression of the exponential form of the translation matrix is given here, once the eigenvectros and the eigenvalues of G have been found. In addition, the eigenproblem relative to the matrix which transforms outgoing waves scattered by a centre in a set of spherical free waves centered at a different point is solved
Multiple Scattering of Gamma Radiation in a Spherical Concrete Wall Room
Energy Technology Data Exchange (ETDEWEB)
Leimdoerfer, M
1962-12-15
The Monte Carlo method has been applied for the calculation of the energy flux of scattered gamma radiation in a spherical room surrounded by an infinitely thick spherical wall and with a point source at the centre. Source energies were I, 2, 4, 6, and 10 MeV. The main investigation was carried out at a room radius of 500 cm but, for the 1 MeV source, the influence of varying the room radius down to 1 cm was analysed. The results contain energy distributions of the first four successive reflection components at the centre of the room and at the wall surface, as well as spatial distributions of the successive energy flux components. The neglect of reflection contributions of order five and higher was estimated to introduce an error of less than 0. 2 % of the total scattered energy flux. An analytical approximation is shown to produce a useful and easily applicable method of predicting the amount of scattered radiation in a spherical room.
Multiple Scattering of Gamma Radiation in a Spherical Concrete Wall Room
International Nuclear Information System (INIS)
Leimdoerfer, M.
1962-12-01
The Monte Carlo method has been applied for the calculation of the energy flux of scattered gamma radiation in a spherical room surrounded by an infinitely thick spherical wall and with a point source at the centre. Source energies were I, 2, 4, 6, and 10 MeV. The main investigation was carried out at a room radius of 500 cm but, for the 1 MeV source, the influence of varying the room radius down to 1 cm was analysed. The results contain energy distributions of the first four successive reflection components at the centre of the room and at the wall surface, as well as spatial distributions of the successive energy flux components. The neglect of reflection contributions of order five and higher was estimated to introduce an error of less than 0. 2 % of the total scattered energy flux. An analytical approximation is shown to produce a useful and easily applicable method of predicting the amount of scattered radiation in a spherical room
Energy Technology Data Exchange (ETDEWEB)
Nakatsuka, Takao [Okayama Shoka University, Laboratory of Information Science, Okayama (Japan); Okei, Kazuhide [Kawasaki Medical School, Dept. of Information Sciences, Kurashiki (Japan); Iyono, Atsushi [Okayama university of Science, Dept. of Fundamental Science, Faculty of Science, Okayama (Japan); Bielajew, Alex F. [Univ. of Michigan, Dept. Nuclear Engineering and Radiological Sciences, Ann Arbor, MI (United States)
2015-12-15
Simultaneous distribution between the deflection angle and the lateral displacement of fast charged particles traversing through matter is derived by applying numerical inverse Fourier transforms on the Fourier spectral density solved analytically under the Moliere theory of multiple scattering, taking account of ionization loss. Our results show the simultaneous Gaussian distribution at the region of both small deflection angle and lateral displacement, though they show the characteristic contour patterns of probability density specific to the single and the double scatterings at the regions of large deflection angle and/or lateral displacement. The influences of ionization loss on the distribution are also investigated. An exact simultaneous distribution is derived under the fixed energy condition based on a well-known model of screened single scattering, which indicates the limit of validity of the Moliere theory applied to the simultaneous distribution. The simultaneous distribution will be valuable for improving the accuracy and the efficiency of experimental analyses and simulation studies relating to charged particle transports. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Oklopčić, Antonija [California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Hirata, Christopher M. [Center for Cosmology and Astroparticle Physics, Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210 (United States); Heng, Kevin, E-mail: oklopcic@astro.caltech.edu [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012, Bern (Switzerland)
2017-09-10
The diagnostic potential of the spectral signatures of Raman scattering, imprinted in planetary albedo spectra at short optical wavelengths, has been demonstrated in research on planets in the solar system, and has recently been proposed as a probe of exoplanet atmospheres, complementary to albedo studies at longer wavelengths. Spectral features caused by Raman scattering offer insight into the properties of planetary atmospheres, such as the atmospheric depth, composition, and temperature, as well as the possibility of detecting and spectroscopically identifying spectrally inactive species, such as H{sub 2} and N{sub 2}, in the visible wavelength range. Raman albedo features, however, depend on both the properties of the atmosphere and the shape of the incident stellar spectrum. Identical planetary atmospheres can produce very different albedo spectra depending on the spectral properties of the host star. Here we present a set of geometric albedo spectra calculated for atmospheres with H{sub 2}/He, N{sub 2}, and CO{sub 2} composition, irradiated by different stellar types ranging from late A to late K stars. Prominent albedo features caused by Raman scattering appear at different wavelengths for different types of host stars. We investigate how absorption due to the alkali elements sodium and potassium may affect the intensity of Raman features, and we discuss the preferred strategies for detecting Raman features in future observations.
Adolph, C.; Aghasyan, M.; Akhunzyanov, R.; Alexeev, M.G.; Alexeev, G.D.; Amoroso, A.; Andrieux, V.; Anfimov, N.V.; Anosov, V.; Augustyniak, W.; Austregesilo, A.; Azevedo, C.D.R.; Badelek, B.; Balestra, F.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E.R.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Buechele, M.; Capozza, L.; Chang, W. -C.; Chatterjee, C.; Chiosso, M.; Choi, I.; Chung, S. -U.; Cicuttin, A.; Crespo, M.L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S.S.; Dasgupta, S.; Denisov, O. Yu.; Dhara, L.; Donskov, S.V.; Doshita, N.; Duic, V.; Duennweber, W.; Dziewiecki, M.; Efremov, A.; Eversheim, P.D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; Fischer, H.; Franco, C.; von Hohenesche, N. du Fresne; Friedrich, J.M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O.P.; Gerassimov, S.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmueller, S.; Grasso, A.; Grosse Perdekamp, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; von Harrach, D.; Hashimoto, R.; Heinsius, F.H.; Heitz, R.; Herrmann, F.; Hinterberger, F.; Horikawa, N.; dHose, N.; Hsieh, C. -Y.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Joosten, R.; Joerg, P.; Kabuss, E.; Ketzer, B.; Khaustov, G.V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J.H.; Kolosov, V.N.; Kondo, K.; Koenigsmann, K.; Konorov, I.; Konstantinov, V.F.; Kotzinian, A.M.; Kouznetsov, O.M.; Kuhn, R.; Kraemer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z.V.; Kulinich, Y.; Kunne, F.; Kurek, K.; Kurjata, R.P.; Lednev, A.A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G.K.; Marchand, C.; Marianski, B.; Martin, A.; Marzec, J.; Matousek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.V.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Mikhasenko, M.; Mitrofanov, E.; Mitrofanov, N.; Miyachi, Y.; Montuenga, P.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nikolaenko, V.I.; Novy, J.; Nowak, W.-D.; Nukazuka, G.; Nunes, A.S.; Olshevsky, A.G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J. -C.; Pereira, F.; Pesek, M.; Peshekhonov, D.V.; Pierre, N.; Platchkov, S.; Pochodzalla, J.; Polyakov, V.A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Roskot, M.; Ryabchikov, D.I.; Rybnikov, A.; Rychter, A.; Salac, R.; Samoylenko, V.D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I.A.; Sawada, T.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schoenning, K.; Schopferer, S.; Seder, E.; Selyunin, A.; Shevchenko, O. Yu.; Steffen, D.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Smolik, J.; Sozzi, F.; Srnka, A.; Stolarski, M.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Tasevsky, M.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Tosello, F.; Tskhay, V.; Uhl, S.; Veloso, J.; Virius, M.; Vondra, J.; Weisrock, T.; Wilfert, M.; Windmolders, R.; ter Wolbeek, J.; Zaremba, K.; Zavada, P.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zink, A.
2017-01-10
Multiplicities of charged pions and unidentified hadrons produced in deep-inelastic scattering were measured in bins of the Bjorken scaling variable $x$, the relative virtual-photon energy $y$ and the relative hadron energy $z$. Data were obtained by the COMPASS Collaboration using a 160 GeV muon beam and an isoscalar target ($^6$LiD). They cover the kinematic domain in the photon virtuality $Q^2$ > 1(GeV/c$)^2$, $0.004 < x < 0.4$, $0.2 < z < 0.85$ and $0.1 < y < 0.7$. In addition, a leading-order pQCD analysis was performed using the pion multiplicity results to extract quark fragmentation functions.
Directory of Open Access Journals (Sweden)
C. Adolph
2017-01-01
Full Text Available Multiplicities of charged pions and charged hadrons produced in deep-inelastic scattering were measured in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y and the relative hadron energy z. Data were obtained by the COMPASS Collaboration using a 160GeV muon beam and an isoscalar target (6LiD. They cover the kinematic domain in the photon virtuality Q2>1(GeV/c2, 0.004
Wang, Kezhi
2015-06-01
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.
Wang, Kezhi; Wang, Tian; Chen, Yunfei; Alouini, Mohamed-Slim
2015-01-01
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.
Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio
1999-07-01
Over the past few years, there has been significant research activity devoted to the application of fluorescence spectroscopy to strongly scattering media, where photons propagate diffusely. Much of this activity focused on fluorescence as a source of contrast enhancement in optical tomography. Our efforts have emphasized the quantitative recovery of fluorescence parameters for spectroscopy. Using a frequency-domain diffusion-based model, we have successfully recovered the lifetime, the absolute quantum yield, the fluorophore concentration, and the emission spectrum of the fluorophore, as well as the absorption and the reduced scattering coefficients at the emission wavelength of the medium in different measurements. In this contribution, we present a sensitive monitor of the binding between ethidium bromide and bovine cells in fresh milk. The spectroscopic contrast was the approximately tenfold increase in the ethidium bromide lifetime upon binding to DNA. The measurement clearly demonstrated that we could quantitatively measure the density of cells in the milk, which is an application vital to the tremendous economic burden of bovine subclinical mastitis detection. Furthermore, we may in principle use the spirit of this technique as a quantitative monitor of the binding of fluorescent drugs inside tissues. This is a first step towards lifetime spectroscopy in tissues.
Studies on laser beam propagation and stimulated scattering in multiple beam experiments
International Nuclear Information System (INIS)
Labaune, C.; Lewis, K.; Bandulet, H.; Lewis, K.; Depierreux, S.; Huller, S.; Masson-Laborde, P.E.; Pesme, D.; Riazuelo, G.
2006-01-01
The propagation and stimulated scattering of intense laser beams interacting with underdense plasmas are two important issues for inertial confinement fusion (ICF). The purpose of this work was to perform experiments under well-controlled interaction conditions and confront them with numerical simulations to test the physics included in the codes. Experimental diagnostics include time and space resolved images of incident and SBS light and of SBS-ion acoustic activity. New numerical diagnostics, including similar constraints as the experimental ones and the treatment of the propagation of the light between the emitting area and the detectors, have been developed. Particular care was put to include realistic plasma density and velocity profiles, as well as laser pulse shape in the simulations. In the experiments presented in this paper, the interaction beam was used with a random phase plate (RPP) to produce a statistical distribution of speckles in the focal volume. Stimulated Brillouin Scattering (SBS) was described using a decomposition of the spatial scales which provides a predictive modeling of SBS in an expanding mm-scale plasma. Spatial and temporal behavior of the SBS-ion acoustic waves was found to be in good agreement with the experimental ones for two laser intensities. (authors)
Yang, Hongfei; Li, Juan
2016-01-01
The present study examined the associations between linking, response to positive affect, and psychological functioning in Chinese college students. The results of conducting multiple mediation analyses indicated that emotion- and self-focused positive rumination mediated the relationship between linking and psychological functioning, whereas…
International Nuclear Information System (INIS)
Al-Ain, F.; Attar, J.; Hussein, F.
2007-05-01
A field experiment was conducted on sandy clay and clayey soils at Deir Ezzor to compare the performance of Neutron Scattering (NS) relative to a capacitance probe (CP), Diviner2000, in our local conditions under saline soils. The effect of soil electrical conductivity (ECe) and bulk density (?b) on the precession, accuracy and sensitivity of the tested equipment s were evaluated. Also, the ability to improve the calibration equation for these equipment s, by including ECe and ?b as independent variables in the equation formula, was studied. The study showed that, Diviner2000 was very sensitive to soil bulk density and electrical conductivity of the soil (i.e. soil salinity) compared to the NS. Multiple non-linear regressions improved the fitting when both parameters (?b and ECe) were included in the equation, even though the correlation coefficient (R2) remained low in the case of Diviner2000.(author)
Mann, Nishan; Hughes, Stephen
2018-02-01
We present the analytical and numerical details behind our recently published article [Phys. Rev. Lett. 118, 253901 (2017), 10.1103/PhysRevLett.118.253901], describing the impact of disorder-induced multiple scattering on counterpropagating solitons in photonic crystal waveguides. Unlike current nonlinear approaches using the coupled mode formalism, we account for the effects of intraunit cell multiple scattering. To solve the resulting system of coupled semilinear partial differential equations, we introduce a modified Crank-Nicolson-type norm-preserving implicit finite difference scheme inspired by the transfer matrix method. We provide estimates of the numerical dispersion characteristics of our scheme so that optimal step sizes can be chosen to either minimize numerical dispersion or to mimic the exact dispersion. We then show numerical results of a fundamental soliton propagating in the presence of multiple scattering to demonstrate that choosing a subunit cell spatial step size is critical in accurately capturing the effects of multiple scattering, and illustrate the stochastic nature of disorder by simulating soliton propagation in various instances of disordered photonic crystal waveguides. Our approach is easily extended to include a wide range of optical nonlinearities and is applicable to various photonic nanostructures where power propagation is bidirectional, either by choice, or as a result of multiple scattering.
International Nuclear Information System (INIS)
Wang Hai-Hua; Sun Xian-Ming
2012-01-01
The mixture of water cloud droplets with black carbon impurities is modeled by external and internal mixing models. The internal mixing model is modeled with a two-layered sphere (water cloud droplets containing black carbon (BC) inclusions), and the single scattering and absorption characteristics are calculated at the visible wavelength of 0.55 μm by using the Lorenz—Mie theory. The external mixing model is developed assuming that the same amount of BC particles are mixed with the water droplets externally. The multiple scattering characteristics are computed by using the Monte Carlo method. The results show that when the size of the BC aerosol is small, the reflection intensity of the internal mixing model is bigger than that of the external mixing model. However, if the size of the BC aerosol is big, the absorption of the internal mixing model will be larger than that of the external mixing model. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Multiple scattering corrections to the Beer-Lambert law. 2: Detector with a variable field of view.
Zardecki, A; Tam, W G
1982-07-01
The multiple scattering corrections to the Beer-Lambert law in the case of a detector with a variable field of view are analyzed. We introduce transmission functions relating the received radiant power to reference power levels relevant to two different experimental situations. In the first case, the transmission function relates the received power to a reference power level appropriate to a nonattenuating medium. In the second case, the reference power level is established by bringing the receiver to the close-up position with respect to the source. To examine the effect of the variation of the detector field of view the behavior of the gain factor is studied. Numerical results modeling the laser beam propagation in fog, cloud, and rain are presented.
Martikainen, Julia; Penttilä, Antti; Gritsevich, Maria; Muinonen, Karri
2017-10-01
Asteroids have remained mostly the same for the past 4.5 billion years, and provide us information on the origin, evolution and current state of the Solar System. Asteroids and meteorites can be linked by matching their respective reflectance spectra. This is difficult, because spectral features depend strongly on the surface properties, and meteorite surfaces are free of regolith dust present in asteroids. Furthermore, asteroid surfaces experience space weathering which affects their spectral features.We present a novel simulation framework for assessing the spectral properties of meteorites and asteroids and matching their reflectance spectra. The simulations are carried out by utilizing a light-scattering code that takes inhomogeneous waves into account and simulates light scattering by Gaussian-random-sphere particles large compared to the wavelength of the incident light. The code uses incoherent input and computes phase matrices by utilizing incoherent scattering matrices. Reflectance spectra are modeled by combining olivine, pyroxene, and iron, the most common materials that dominate the spectral features of asteroids and meteorites. Space weathering is taken into account by adding nanoiron into the modeled asteroid spectrum. The complex refractive indices needed for the simulations are obtained from existing databases, or derived using an optimization that utilizes our ray-optics code and the measured spectrum of the material.We demonstrate our approach by applying it to the reflectance spectrum of (4) Vesta and the reflectance spectrum of the Johnstown meteorite measured with the University of Helsinki integrating-sphere UV-Vis-NIR spectrometer.Acknowledgments. The research is funded by the ERC Advanced Grant No. 320773 (SAEMPL).
Freedom poverty: a new tool to identify the multiple disadvantages affecting those with CVD.
Callander, Emily J; Schofield, Deborah J; Shrestha, Rupendra N
2013-06-20
It is recognised that CVD affects an individual's financial situation, placing them in income poverty. However, recent developments in poverty measurement practice recognises other forms of disadvantage other than low income, such as poor health and insufficient education also affect living standards. Using the Freedom Poverty Measure, the multiple forms of disadvantage experienced by those with no health condition, heart disease, other diseases of the circulatory system, and all other health conditions was assessed using data on the adult Australian population contained in the 2003 Survey of Disability, Ageing and Carers. 24% of those with heart disease and 23% of those with other diseases of the circulatory system were in freedom poverty, suffering from multiple forms of disadvantage. Those with heart disease and those with other diseases of the circulatory system were around three times more likely to be in freedom poverty (OR 3.02, 95% CI: 2.29-3.99, p<.0001; OR 2.78, 95% CI: 1.94-3.98, p<.0001) than those with no health condition. Recognising the multiple forms of disadvantage suffered by those with CVD provides a clearer picture of their living standards than just looking at their income alone and the high proportion of individuals with CVD that are suffering from multiple forms of disadvantage should make them a target for policy makers wishing to improve living standards. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Affective mediators of a physical activity intervention for depression in multiple sclerosis.
Kratz, Anna L; Ehde, Dawn M; Bombardier, Charles H
2014-02-01
Previous analyses showed that a telephone-based intervention to increase physical activity in individuals with multiple sclerosis (MS) and depression resulted in significantly improved depressive symptoms compared to a wait-list control group. The aim of this study was to test positive affect and negative affect as mediators of the effect of the physical activity counseling on depressive symptoms. Ninety-two adults with MS, who met diagnostic criteria for either major depression or dysthymia and who reported low levels of physical activity, were randomized 1:1 to a 12-week telephone-based motivational interviewing (MI) intervention to improve physical activity (n = 44) or to a 12-week wait-list control group (n = 48). Self-reported positive and negative affect, physical activity, and depressive symptoms were gathered at baseline and postintervention. Path-analysis was used to test whether positive affect and negative affect mediated the positive effects of the intervention on depressive symptoms. Both positive and negative affect were significant mediators of the effects of the intervention on depressive symptoms; however, only positive affect mediated the association between changes in physical activity and improved depressive symptoms. Findings support physical activity and positive affect as key mediators of the MI treatment effect on improved mood. Decreases in negative affect were also evident in the treatment group, but were not related to improved physical activity. Findings may suggest the use of exercise-based interventions in conjunction with treatments that specifically target negative affective mechanisms for depression. PsycINFO Database Record (c) 2014 APA, all rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Palacios G, J., E-mail: jpalacios@ipn.mx [IPN, Escuela Superior de Fisica y Matematicas, San Pedro Zacatenco 07738, Ciudad de Mexico (Mexico)
2016-11-01
The integrated intensity of Debye-Scherrer (D-S) rings, arising from an eventual second diffraction process of a diffracted X-ray beam, was calculated. This represents the amount of intensity not arriving at the detector as oriented to register the first diffraction process, and as result, a measure of secondary extinction. Thus the objective is to investigate in this way if secondary extinction affects measurements of X-ray diffraction from textured polycrystals. This has been suggested by differences of pole density maxima observed between measured first and second order pole figures in strongly textured materials. Calculations are performed for a detector scan (varying only 2θ), and the integrated intensity is determined for first and second order diffraction conditions of a general plane (hkl). Normalization through corresponding powder is performed. It is found that this special case of multiple scattering effect, indeed affects both orders essentially in the same way. If corresponding detector scan measurements verify this, then the observed differences between pole density maxima of pole figures of different order cannot be attributed to secondary extinction. Instead, they can be attributed to heterogeneous texture or error propagation. On the other hand, if the detector scans do exhibit a difference as that of pole density maxima, these differences can possibly be attributed to primary extinction. (Author)
Experimental study of single-particle inclusive hadron scattering and associated multiplicities
International Nuclear Information System (INIS)
Brenner, A.E.; Carey, D.C.; Elias, J.E.; Garbincius, P.H.; Mikenberg, G.; Polychronakos, V.A.; Aitkenhead, W.; Barton, D.S.; Brandenburg, G.W.; Busza, W.; Dobrowolski, T.; Friedman, J.I.; Kendall, H.W.; Lyons, T.; Nelson, B.; Rosenson, L.; Toy, W.; Verdier, R.; Votta, L.; Chiaradia, M.T.; DeMarzo, C.; Favuzzi, C.; Germinario, G.; Guerriero, L.; LaVopa, P.; Maggi, G.; Posa, F.; Selvaggi, G.; Spinelli, P.; Waldner, F.; Meunier, R.; Cutts, D.; Dulude, R.S.; Lanou, R.E. Jr.; Massimo, J.T.
1982-01-01
An experiment using the Fermilab single arm spectrometer (SAS) facility and an associated nonmagnetic vertex detector studied the reactions a+p→c+X where a and c were π +- , K +- , p, or p-bar. Extensive measurements were made at 100 and 175 GeV/c beam momenta with the outgoing hadrons detected in the SAS covering a kinematic range 0.12< x<1.0 and p/sub T/<1.25 GeV/c. Additional data covering a more restricted range in x were also gathered at 70 GeV/c incident momentum. In this high-statistics experiment, the identification of both the incoming and outgoing charged hadrons were made with a total of eight Cerenkov counters. New and extensive single-particle inclusive data for charged-particle production in low-p/sub T/ hadronic fragmentation are presented. The average associated charged-particle multiplicity and pseudorapidity distributions are also given
International Nuclear Information System (INIS)
Lohmander, H.
1995-04-01
Charged particle and transverse energy flow for deep inelastic ep scattering at HERA have been investigated in the hadronic center of mass systems as a function of pseudorapidity η* in different W 2 and Q 2 intervals. In addition, the mean charged particle multiplicity ch > and the mean transverse energy * Τ > as a function of W 2 and Q 2 have been studied. The measurements were made in the kinematic region 85 2 2 . The ch > was found to increase with increasing W 2 at fixed Q 2 but did not show any significant dependence on Q 2 at fixed W 2 . The best description of the mean charged multiplicity is given by ch >=a+b·ln(W 2 /GeV 2 ) with a=-1.38±0.07 and b=0.93±0.05. The * Τ > increased both with increasing W 2 at fixed Q 2 and with increasing Q 2 at fixed W 2 . The mean transverse energy is described by * Τ >=a+b·ln(W 2 /GeV 2 )+c·ln (Q 2 /GeV 2 )GeV with a=-5.93±0.07, b=1.28±0.06 and c=0.69±0.02. Different QCD models have been compared with data. Only the Color Dipole Model, as implemented in the Monte Carlo program Ariadne, describes the data satisfactorily. 29 refs
Directory of Open Access Journals (Sweden)
Piotr Brzezinski
2012-01-01
Full Text Available Introduction: Lupus erythematosus is a chronic, inflammatory autoimmune disease that can affect multiple organs. Lupus can affect many parts of the body, especially in systemic lupus erythematosus (SLE; affected tissues may include the joints, skin, kidneys, heart, lungs, blood vessels, and brain. Case report: A 46-year-old female presented with pruritus, photosensitivity and edema of the cheeks of about 2 years duration, and was evaluated by a dermatologist. On examination, multiple telangiectasias were present on the cheeks, with erythema, edema and a malar rash observed. A review of systems documented breathing difficulty and pleuitic pain, joint pain and joint edema, photosensitivity, cardiac dysrhythmia, and periodic pain in the back close to the kidneys. Methods: Skin biopsies for hematoxylin and eosin testing, as well for direct and indirect immunofluorescence were performed, in addition to multiple diagnostic blood tests, chest radiography and directed immunologic testing. Results: The blood testing showed elevated C-reactive protein. Direct and indirect immunofluorescence testing utilizing monkey esophagus, mouse and pig heart and kidney, normal human eyelid skin and veal brain demonstrated strong reactivity to several components of smooth muscle, nerves, blood vessels, skin basement membrane zone and sweat gland ducts and skin meibomian glands. Anti-endomysium antibodies were detected as well as others, especially using FITC conjugated Complement/C1q, FITC conjugated anti-human immunoglobulin IgG and FITC conjugated anti-human fibrinogen. Conclusions: We conclude that both direct and indirect immunofluorescence using several substrates can unveil previously undocumented autoantibodies in multiple organs in lupus erythematosus, and that these findings could be utilized to complement existing diagnostic testing for this disorder.
International Nuclear Information System (INIS)
Zhang, X.; Gonis, A.; MacLaren, J.M.
1989-01-01
We present a new real-space multiple-scattering-theory method for the solution of the Schroedinger equation and the calculation of the electronic structure of solid materials with full or reduced symmetry. The method is based on the concept of semi-infinite periodicity (SIP), rather than translational invariance, and on the property of removal invariance of the scattering matrix of systems with SIP. This latter property allows one to replace the usual Brillouin-zone integrals in reciprocal space by a self-consistency equation for the t matrix, which is sufficient for the determination of the Green function and related properties. Because it is developed entirely in direct space, the method provides a unified treatment of the electronic structure of bulk materials, surfaces, interfaces and grain boundaries (coherent or incoherent), impurities of interstitial or substitutional kinds, and can be easily extended to treat concentrated, substitutionally disordered alloys. One of its advantages over methods based on Bloch's theorem and reciprocal space is the great simplicity of setting up and running the associated computer codes even for complex structures, and structures with reduced or no symmetry that lie outside the realm of applicability of conventional methods. We present the results of model calculations for one-dimensional and three-dimensional model systems as well as for three-dimensional realistic materials. Where appropriate, these results are compared with those obtained through conventional techniques, and give an indication of the method's flexibility and reliability. Our applications of this method to this point are discussed, and our plans for future development are presented
Kulinich, P; Krylov, V
2004-01-01
Novel String Banana Template Method (SBTM) for track reconstruction in difficult conditions is proposed and implemented for off-line analysis of relativistic heavy ion collision events. The main idea of the method is in use of features of ensembles of tracks selected by 3-fold coincidence. Two steps model of track is used: the first one - averaged over selected ensemble and the second - per event dependent. It takes into account Multiple Scattering (MS) for this particular track. SBTM relies on use of stored templates generated by precise Monte Carlo simulation, so it's more time efficient for the case of 2D spectrometer. All data required for track reconstruction in such difficult conditions could be prepared in convenient format for fast use. Its template based nature and the fact that the SBTM track model is actually very close to the hits implies that it can be implemented in a firmware processor. In this report a block diagram of firmware based pre-processor for track reconstruction in CMS-like Si tracke...
Polarized neutron scattering study of the multiple order parameter system NdB4
Metoki, N.; Yamauchi, H.; Matsuda, M.; Fernandez-Baca, J. A.; Watanuki, R.; Hagihala, M.
2018-05-01
Neutron polarization analysis has been carried out in order to clarify the magnetic structures of multiple order parameter f -electron system NdB4. We confirmed the noncollinear "all-in all-out" structure (Γ4) of the in-plane moment, which is in good agreement with our previous neutron powder diffraction study. We found that the magnetic moment along the c -axis mc showed diagonally antiferromagnetic structure (Γ10), inconsistent with previously reported "vortex" structure (Γ2). The microscopic mixture of these two structures with q⃗0=(0 ,0 ,0 ) appears in phase II and remains stable in phases III and IV, where an incommensurate modulation coexists. The unusual magnetic ordering is phenomenologically understood via Landau theory with the primary order parameter Γ4 coupled with higher-order secondary order parameter Γ10. The magnetic moments were estimated to be 1.8 ±0.2 and 0.2 ±0.05 μB at T =7.5 K for Γ4 and Γ10, respectively. We also found a long-period incommensurate modulation of the q⃗1=(0 ,0 ,1 /2 ) antiferromagnetic structure of mc with the propagation q⃗s 1=(0.14 ,0.14 ,0.1 ) and q⃗s 2=(0.2 ,0 ,0.1 ) in phase III and IV, respectively. The amplitude of sinusoidal modulation was about mc=1.0 ±0.2 μB at T =1.5 K. The local (0 ,0 ,1 /2 ) structure consists of in-plane ferromagnetic and out-of-plane antiferromagnetic coupling of mc, opposite to the coexisting Γ10. The mc of Γ10 is significantly enhanced up to 0.6 μB at T =1.5 K, which is accompanied by the incommensurate modulations. The Landau phenomenological approach indicates that the higher-order magnetic and/or multipole interactions based on the pseudoquartet f -electron state play important roles.
Thomson, C. J.
2004-12-01
Pseudodifferential operators (PSDOs) yield in principle exact one--way seismic wave equations, which are attractive both conceptually and for their promise of computational efficiency. The one--way operators can be extended to include multiple--scattering effects, again in principle exactly. In practice approximations must be made and, as an example, the variable--wavespeed Helmholtz equation for scalar waves in two space dimensions is here factorized to give the one--way wave equation. This simple case permits clear identification of a sequence of physically reasonable approximations to be used when the mathematically exact PSDO one--way equation is implemented on a computer. As intuition suggests, these approximations hinge on the medium gradients in the direction transverse to the main propagation direction. A key point is that narrow--angle approximations are to be avoided in the interests of accuracy. Another key consideration stems from the fact that the so--called ``standard--ordering'' PSDO indicates how lateral interpolation of the velocity structure can significantly reduce computational costs associated with the Fourier or plane--wave synthesis lying at the heart of the calculations. The decision on whether a slow or a fast Fourier transform code should be used rests upon how many lateral model parameters are truly distinct. A third important point is that the PSDO theory shows what approximations are necessary in order to generate an exponential one--way propagator for the laterally varying case, representing the intuitive extension of classical integral--transform solutions for a laterally homogeneous medium. This exponential propagator suggests the use of larger discrete step sizes, and it can also be used to approach phase--screen like approximations (though the latter are not the main interest here). Numerical comparisons with finite--difference solutions will be presented in order to assess the approximations being made and to gain an understanding
International Nuclear Information System (INIS)
Ando, K.; Bando, H.; Krenciglowa, E.M.
1978-01-01
A three-particle one-hole multiple scattering equation for the two-valence nucleon system is derived and used to give the 3p1h contribution to the Q-box. Full exchanges among the 3p1h intermediate configurations are incorporated and the energy dependence of the underlying reaction matrix is properly taken into account. The equation includes processes comparable in scope to a large scale [2p+3p1h] shell model but is embedded within the framework of the diagrammatic expansion for the effective interaction. Using an essentially 'exact', energy-dependent reaction matrix this formalism is applied to the mass-18 system. The roles of various correlations and proper energy dependence of the reaction matrix are closely examined. In comparison with previous calculations, the present results are significantly more attractive and give the experimental level ordering in both the Tsup(π) = 0 + and 1 + low-lying spectra. Low-lying particle-particle correlations are found to play a dominant role. (Auth.)
International Nuclear Information System (INIS)
Strandlie, A.; Wroldsen, J.
2006-01-01
If any of the probability densities involved in track fitting deviate from the Gaussian assumption, it is plausible that a non-linear estimator which better takes the actual shape of the distribution into account can do better. One such non-linear estimator is the Gaussian-sum filter, which is adequate if the distributions under consideration can be approximated by Gaussian mixtures. The main purpose of this paper is to present a Gaussian-sum filter for track fitting, based on a two-component approximation of the distribution of angular deflections due to multiple scattering. In a simulation study within a linear track model the Gaussian-sum filter is shown to be a competitive alternative to the Kalman filter. Scenarios at various momenta and with various maximum number of components in the Gaussian-sum filter are considered. Particularly at low momenta the Gaussian-sum filter yields a better estimate of the uncertainties than the Kalman filter, and it is also slightly more precise than the latter
International Nuclear Information System (INIS)
Ankowski, A.; Graczyk, K.; Nowak, J.; Sobczyk, J.; Antonello, M.; Cavanna, F.; Piano Mortari, G.; Segreto, E.; Aprili, P.; Arneodo, F.; Palamara, O.; Badertscher, A.; Ge, Y.; Laffranchi, M.; Messina, M.; Rubbia, A.; Baiboussinov, B.; Baldo Ceolin, M.; Centro, S.; Gibin, D.; Guglielmi, A.; Meng, G.; Pietropaolo, F.; Varanini, F.; Ventura, S.; Battistoni, G.; Muraro, S.; Sala, P.R.; Benetti, P.; Borio di Tigliole, A.; Brunetti, R.; Calligarich, E.; De Vecchi, C.; Dolfini, R.; Gigli Berzolari, A.; Grandi, L.; Mauri, F.; Menegolli, A.; Montanari, C.; Piazzoli, A.; Prata, M.; Prata, M.C.; Przewlocki, P.; Rappoldi, A.; Raselli, G.L.; Rossella, M.; Rubbia, C.; Scannicchio, D.; Vignoli, C.; Bueno, A.; Carmona, M.C.; Garcia-Gamez, D.; Lozano, J.; Martinez de la Ossa, A.; Melgarejo, A.J.; Navas, S.; Carbonara, F.; Cocco, A.G.; Di Cicco, A.; Ereditato, A.; Fiorillo, G.; Rossi, B.; Cennini, P.; Ferrari, A.; Cesana, A.; Terrani, M.; Cline, D.B.; Lisowski, B.; Matthey, C.; Otwinowski, S.; Seo, Y.; Wang, H.; Yang, X.; Cieslik, K.; Dabrowska, A.; Markiewicz, M.; Stefan, D.; Szarska, M.; Wachala, T.; Zalewska, A.; Gil-Botella, I.; Holeczek, J.; Kisiel, J.; Kielczewska, D.; Lagoda, J.; Posiadala, M.; Kozlowski, T.; Mijakowski, P.; Rondio, E.; Stepaniak, J.; Szeptycka, M.; Periale, L.; Picchi, P.; Polchlopek, W.; Sergiampietri, F.; Sulej, R.
2006-01-01
The ICARUS collaboration has demonstrated, following the operation of a 600 ton (T600) detector at shallow depth, that the technique based on liquid argon time projection chambers is now mature. The study of rare events, not contemplated in the standard model, can greatly benefit from the use of this kind of detectors. In particular, a deeper understanding of atmospheric neutrino properties will be obtained thanks to the unprecedented quality of the data ICARUS provides. However if we concentrate on the T600 performance, most of the ν μ charged current sample will be partially contained, due to the reduced dimensions of the detector. In this article, we address the problem of how well we can determine the kinematics of events having partially contained tracks. The analysis of a large sample of atmospheric muons collected during the T600 test run demonstrates that, in case the recorded track is at least one meter long, the muon momentum can be reconstructed by an algorithm that measures the multiple Coulomb scattering along the particle's path. Moreover, we show that momentum resolution can be improved by almost a factor two using an algorithm based on the Kalman filtering technique. (orig.)
Valier-Brasier, Tony; Conoir, Jean-Marc; Coulouvrat, François; Thomas, Jean-Louis
2015-10-01
Sound propagation in dilute suspensions of small spheres is studied using two models: a hydrodynamic model based on the coupled phase equations and an acoustic model based on the ECAH (ECAH: Epstein-Carhart-Allegra-Hawley) multiple scattering theory. The aim is to compare both models through the study of three fundamental kinds of particles: rigid particles, elastic spheres, and viscous droplets. The hydrodynamic model is based on a Rayleigh-Plesset-like equation generalized to elastic spheres and viscous droplets. The hydrodynamic forces for elastic spheres are introduced by analogy with those of droplets. The ECAH theory is also modified in order to take into account the velocity of rigid particles. Analytical calculations performed for long wavelength, low dilution, and weak absorption in the ambient fluid show that both models are strictly equivalent for the three kinds of particles studied. The analytical calculations show that dilatational and translational mechanisms are modeled in the same way by both models. The effective parameters of dilute suspensions are also calculated.
Severini, Giacomo; Manca, Mario; Ferraresi, Giovanni; Caniatti, Luisa Maria; Cosma, Michela; Baldasso, Francesco; Straudi, Sofia; Morelli, Monica; Basaglia, Nino
2017-06-01
Clinical Gait Analysis is commonly used to evaluate specific gait characteristics of patients affected by Multiple Sclerosis. The aim of this report is to present a retrospective cross-sectional analysis of the changes in Clinical Gait Analysis parameters in patients affected by Multiple Sclerosis. In this study a sample of 51 patients with different levels of disability (Expanded Disability Status Scale 2-6.5) was analyzed. We extracted a set of 52 parameters from the Clinical Gait Analysis of each patient and used statistical analysis and linear regression to assess differences among several groups of subjects stratified according to the Expanded Disability Status Scale and 6-Minutes Walking Test. The impact of assistive devices (e.g. canes and crutches) on the kinematics was also assessed in a subsample of patients. Subjects showed decreased range of motion at hip, knee and ankle that translated in increased pelvic tilt and hiking. Comparison between the two stratifications showed that gait speed during 6-Minutes Walking Test is better at discriminating patients' kinematics with respect to Expanded Disability Status Scale. Assistive devices were shown not to significantly impact gait kinematics and the Clinical Gait Analysis parameters analyzed. We were able to characterize disability-related trends in gait kinematics. The results presented in this report provide a small atlas of the changes in gait characteristics associated with different disability levels in the Multiple Sclerosis population. This information could be used to effectively track the progression of MS and the effect of different therapies. Copyright © 2017. Published by Elsevier Ltd.
Chang, Carina; Beutler, Bryce D; Cohen, Philip R
2017-06-01
Redness of the nail plate-erythronychia-is a common condition involving one or multiple digits. It may affect the entire nail or present as longitudinal red bands that extend from the proximal nail fold to the distal tip of the nail plate. Rarely, red bands may traverse the nail bed horizontally. Although erythronychia is often idiopathic, it has also been associated with amyloidosis, Darier's disease, lichen planus, and various other cutaneous conditions. We describe the clinical features of a 64-year-old Caucasian man who presented with transverse and longitudinal erythronychia affecting his fingernails. In addition, we review the classification of erythronychia and summarize the acute and chronic conditions that have been associated with this clinical finding. The features of a man with polydactylous transverse and longitudinal erythronychia are presented. In addition, PubMed was used to search the following terms: erythronychia, longitudinal erythronychia, red lunulae, and subungual. All papers were reviewed, and relevant articles, along with their references, were evaluated. Informed consent was obtained from the patient for being included in the study. A 64-year-old Caucasian man with a past medical history significant for testicular cancer and pulmonary embolism presented with multiple horizontal pink-red bands affecting his fingernails. The discoloration was most prominent in the region distal to the lunula. In addition, the nails of the fifth digit of his left hand and third digit of his right hand featured longitudinal red bands extending from the distal curvature of the lunula to the free edge of the nail plate. A diagnosis of polydactylous longitudinal and transverse erythronychia, based on the clinical presentation, was established. Our patient's red bands were asymptomatic and he was not concerned about the cosmetic appearance of his nails; therefore, no additional investigation or treatment was required. Polydactylous transverse erythronychia is a
[The life as a caregiver of a person affected by Chorea Huntington: multiple case study].
Winkler, Evi; Ausserhofer, Dietmar; Mantovan, Franco
2012-10-01
Chorea Huntington is an autosomal dominantly inherited, neurodegenerative brain disorder that leads to involuntary hyperkinesia, psychotic symptoms and dementia. The illness not only changes the life of the person itself but also the world of the caregivers. The challenges in the care of a person which is affected by Chorea Huntington have an effect on the daily living as an assemblage of natural and social conditions. a multiple case study was conducted. It included semi-structured interviews with three caregivers of people with Chorea Huntington in South Tyrol. The qualitative data was analyzed using the qualitative structured analysis of Mayring (2007). The objective of this study was to describe the phenomenon of change of life from family members that care people affected by Chorea Huntington in a specific cultural setting (South Tyrol, Italy). The caregivers reported that the diagnosis of Chorea Huntington leads to negative changes in "relationship and family". Particularly, frustration, aggression, impatience and apathy were perceived as stressful. At the same time they highlight the positive changes through home care. They report that the relationship became more intimate and integral and it was characterized by more cohesion. Family caregivers get valuable support from the home care service, however, they complain that there is no facility in South Tyrol, which is specialized to care people with Chorea Huntington. Therefore, the caregivers have to "give up a lot" and don't have any personal desires, dreams and expectations for the future. The caregivers have learned independently to deal with their changed life step by step, and to see also the positive effects of the caring role. The life of family caregivers of a person which is affected by Chorea Huntington is characterized by abandonment. A continuous and professional care would be important for the affected and his caregiver. A continuous and professional care is important for both, addressing the
Evaluation of a scattered radiation field in a cluster relevant for multiple-energy X-ray holography
International Nuclear Information System (INIS)
Fonda, L.
1996-09-01
We analyze theoretically a recent proposal of utilizing synchrotron radiation to generate an electromagnetic scattering field at a specific target atom inside a material sample. The direct wave coming from a wiggler interferes there with the waves scattered by the surrounding atoms. The suggestion is relevant for obtaining atomic holographic images. (author). 23 refs, 2 figs
International Nuclear Information System (INIS)
Martin, G.; Coca, M.; Capote, R.
1996-01-01
Using Monte Carlo method technique , a computer code which simulates the time of flight experiment to measure double differential cross section was developed. The correction factor for flux attenuation and multiple scattering, that make a deformation to the measured spectrum, were calculated. The energy dependence of the correction factor was determined and a comparison with other works is shown. Calculations for Fe 56 at two different scattering angles were made. We also reproduce the experiment performed at the Nuclear Analysis Laboratory for C 12 at 25 celsius degree and the calculated correction factor for the is measured is shown. We found a linear relation between the scatter size and the correction factor for flux attenuation
Eating in groups: Do multiple social influences affect intake in a fast-food restaurant?
Brindal, Emily; Wilson, Carlene; Mohr, Philip; Wittert, Gary
2015-05-01
This study investigated multiple social influences to determine whether they affect amount eaten at a fast-food environment. Using observational methods, data on meal duration, foods eaten and personal characteristics were collected for 157 McDonald's patrons. Analysis of covariance revealed that female diners ate less kilojoules when eating in mixed- versus same-sex groups (adjusted difference = 967 kJ, p < .05), while male diners eating in mixed-sex company ate more in groups compared to pairs (adjusted difference = 1067 kJ, p = .019). Influences to increase and restrict the amount eaten can operate simultaneously in an eating environment with gender a critical factor for consideration. © The Author(s) 2015.
International Nuclear Information System (INIS)
Bando, H.; Krenciglowa, E.M.; Ando, K.
1979-01-01
Within the systematic framework of the double partition approach, the three-particle one-hole multiple scattering and Q-box formalisms are combined to give the valence-linked and connected energy-independent effective interaction. All low-lying [2p+3p1h] contributions to the mass-18 effective interaction are evaluated using an essentially exact energy-dependent reaction matrix based on the Reid SC potential. The low-lying one-body field of the core nucleus is treated consistently with the underlying reaction matrix G through particle- and hole-line self-energy insertions. Center-of-mass motion, folded diagrams and starting energy dependence are properly taken into account throughout. The low-lying [2p+3p1h] correlations are strongly damped by self-energy insertions. By incorporating only the folded diagram contributions with origins in the low-lying space, the net effect of all low-lying [2p+3p1h] correlations is to give back the bare-G plus second-order core-polarization spectra which are found to be in respectable agreement with the experimental spectra. However, including the full folded diagram contribution, which has additional contributions from the high-lying space through the energy dependence of G, leads to final spectra which deviate sizably from experiment. The present results are conclusive in the sense that the treatment is essentially exact for low-lying [2p+3p1h] correlations which originate from the high-lying two-particle correlations through the reaction matrix G. (Auth.)
Directory of Open Access Journals (Sweden)
Saenko Suzanne V
2010-08-01
Full Text Available Abstract Background The characterization of the molecular changes that underlie the origin and diversification of morphological novelties is a key challenge in evolutionary developmental biology. The evolution of such traits is thought to rely largely on co-option of a toolkit of conserved developmental genes that typically perform multiple functions. Mutations that affect both a universal developmental process and the formation of a novelty might shed light onto the genetics of traits not represented in model systems. Here we describe three pleiotropic mutations with large effects on a novel trait, butterfly eyespots, and on a conserved stage of embryogenesis, segment polarity. Results We show that three mutations affecting eyespot size and/or colour composition in Bicyclus anynana butterflies occurred in the same locus, and that two of them are embryonic recessive lethal. Using surgical manipulations and analysis of gene expression patterns in developing wings, we demonstrate that the effects on eyespot morphology are due to changes in the epidermal response component of eyespot induction. Our analysis of morphology and of gene expression in mutant embryos shows that they have a typical segment polarity phenotype, consistent with the mutant locus encoding a negative regulator of Wingless signalling. Conclusions This study characterizes the segregation and developmental effects of alleles at a single locus that controls the morphology of a lineage-specific trait (butterfly eyespots and a conserved process (embryonic segment polarity and, specifically, the regulation of Wingless signalling. Because no gene with such function was found in the orthologous, highly syntenic genomic regions of two other lepidopterans, we hypothesize that our locus is a yet undescribed, possibly lineage-specific, negative regulator of the conserved Wnt/Wg pathway. Moreover, the fact that this locus interferes with multiple aspects of eyespot morphology and maps to a
Van Stan, John T.; Gay, Trent E.; Lewis, Elliott S.
2016-02-01
Forest canopies alter rainfall reaching the surface by redistributing it as throughfall. Throughfall supplies water and nutrients to a variety of ecohydrological components (soil microbial communities, stream water discharge/chemistry, and stormflow pathways) and is controlled by canopy structural interactions with meteorological conditions across temporal scales. This work introduces and applies multiple correspondence analyses (MCAs) to a range of meteorological thresholds (median intensity, median absolute deviation (MAD) of intensity, median wind-driven droplet inclination angle, and MAD of wind speed) for an example throughfall problem: identification of interacting storm conditions corresponding to temporal concentration in relative throughfall beyond the median observation (⩾73% of rain). MCA results from the example show that equalling or exceeding rain intensity thresholds (median and MAD) corresponded with temporal concentration of relative throughfall across all storms. Under these intensity conditions, two wind mechanisms produced significant correspondences: (1) high, steady wind-driven droplet inclination angles increased surface wetting; and (2) sporadic winds shook entrained droplets from surfaces. A discussion is provided showing that these example MCA findings agree well with previous work relying on more historically common methods (e.g., multiple regression and analytical models). Meteorological threshold correspondences to temporal concentration of relative throughfall at our site may be a function of heavy Tillandsia usneoides coverage. Applications of MCA within other forests may provide useful insights to how temporal throughfall dynamics are affected for drainage pathways dependent on different structures (leaves, twigs, branches, etc.).
Energy Technology Data Exchange (ETDEWEB)
Aspelund, O; Gustafsson, B
1967-05-15
After an introductory discussion of various methods for correction of experimental left-right ratios for polarized multiple-scattering and finite-geometry effects necessary and sufficient formulas for consistent tracking of polarization effects in successive scattering orders are derived. The simplifying assumptions are then made that the scattering is purely elastic and nuclear, and that in the description of the kinematics of the arbitrary Scattering {mu}, only one triple-parameter - the so-called spin rotation parameter {beta}{sup ({mu})} - is required. Based upon these formulas a general discussion of the importance of the correct inclusion of polarization effects in any scattering order is presented. Special attention is then paid to the question of depolarization of an already polarized beam. Subsequently, the afore-mentioned formulas are incorporated in the comprehensive Monte Carlo program MULTPOL, which has been designed so as to correctly account for finite-geometry effects in the sense that both the scattering sample and the detectors (both having cylindrical shapes) are objects of finite dimensions located at finite distances from each other and from the source of polarized fast-neutrons. A special feature of MULTPOL is the application of the method of correlated sampling for reduction of the standard deviations .of the results of the simulated experiment. Typical data of performance of MULTPOL have been obtained by the application of this program to the correction of experimental polarization data observed in n + '{sup 12}C elastic scattering between 1 and 2 MeV. Finally, in the concluding remarks the possible modification of MULTPOL to other experimental geometries is briefly discussed.
Parasites and health affect multiple sexual signals in male common wall lizards, Podarcis muralis
Martín, J.; Amo de Paz, L.; López, P.
2008-01-01
Multiple advertising sexual traits may either advertise different characteristics of male condition or be redundant to reinforce reliability of signals. Research has focused on multiple visual traits. However, in animals that use different multiple additional sensory systems, such as chemoreception,
International Nuclear Information System (INIS)
Singh, Tejbir; Singh, Parjit S
2011-01-01
The pulse height spectra for different thicknesses of portland cement in the reflected geometry has been recorded with the help of a NaI(Tl) scintillator detector and 2 K MCA card using different gamma-ray sources such as Hg 203 (279 keV), Cs 137 (662 keV) and Co 60 (1173 and 1332 keV). It has been observed that the multiple scatter peak for portland cement appears at 110 (±7) keV in all the spectra irrespective of different incident photon energies in the range 279-1332 keV from different gamma-ray sources. Further, the variation in the intensity of the multiple scatter peak with the thickness of portland cement in the backward semi-cylinders has been investigated.
International Nuclear Information System (INIS)
Bando, H.; Krenciglowa, E.M.
1976-01-01
The role of 2p1h correlations in 17 O is studied within a multiple-scattering formalism. An accurate, energy-dependent reaction matrix with orthogonalized plane-wave intermediate states is used to assess the relative importance of particle-particle and particle-hole correlations in the 17 O energies. The effect of energy dependence of the reaction matrix is closely examined. (Auth.)
Al-Qazwini, Zaineb A. T.; Abdullah, Mohamad K.; Mokhtar, Makhfudzah B.
2009-01-01
We measure the stimulated Raman scattering (SRS)-induced tilt in spectral-amplitude-coding optical code-division multiple-access (SAC-OCDMA) systems as a function of system main parameters (transmission distance, power per chip, and number of users) via computer simulations. The results show that SRS-induced tilt significantly increases as transmission distance, power per chip, or number of users grows.
BDNF val66met polymorphism affects aging of multiple types of memory.
Kennedy, Kristen M; Reese, Elizabeth D; Horn, Marci M; Sizemore, April N; Unni, Asha K; Meerbrey, Michael E; Kalich, Allan G; Rodrigue, Karen M
2015-07-01
The BDNF val66met polymorphism (rs6265) influences activity-dependent secretion of brain-derived neurotrophic factor in the synapse, which is crucial for learning and memory. Individuals homozygous or heterozygous for the met allele have lower BDNF secretion than val homozygotes and may be at risk for reduced declarative memory performance, but it remains unclear which types of declarative memory may be affected and how aging of memory across the lifespan is impacted by the BDNF val66met polymorphism. This cross-sectional study investigated the effects of BDNF polymorphism on multiple indices of memory (item, associative, prospective, subjective complaints) in a lifespan sample of 116 healthy adults aged 20-93 years. Advancing age showed a negative effect on item, associative and prospective memory, but not on subjective memory complaints. For item and prospective memory, there were significant age×BDNF group interactions, indicating the adverse effect of age on memory performance across the lifespan was much stronger in the BDNF met carriers than for the val homozygotes. BDNF met carriers also endorsed significantly greater subjective memory complaints, regardless of age, and showed a trend (pmemory performance compared to val homozygotes. These results suggest that genetic predisposition to the availability of brain-derived neurotrophic factor, by way of the BDNF val66met polymorphism, exerts an influence on multiple indices of episodic memory - in some cases in all individuals regardless of age (subjective memory and perhaps associative memory), in others as an exacerbation of age-related differences in memory across the lifespan (item and prospective memory). This article is part of a Special Issue entitled Memory & Aging. Copyright © 2014 Elsevier B.V. All rights reserved.
Multiple Factors Affect Socioeconomics and Wellbeing of Artisanal Sea Cucumber Fishers
Ngaluafe, Poasi; Foale, Simon J.; Cocks, Nicole; Cullis, Brian R.; Lalavanua, Watisoni
2016-01-01
Small-scale fisheries are important to livelihoods and subsistence seafood consumption of millions of fishers. Sea cucumbers are fished worldwide for export to Asia, yet few studies have assessed factors affecting socioeconomics and wellbeing among fishers. We interviewed 476 men and women sea cucumber fishers at multiple villages within multiple locations in Fiji, Kiribati, Tonga and New Caledonia using structured questionnaires. Low rates of subsistence consumption confirmed a primary role of sea cucumbers in income security. Prices of sea cucumbers sold by fishers varied greatly among countries, depending on the species. Gender variation in landing prices could be due to women catching smaller sea cucumbers or because some traders take advantage of them. Dissatisfaction with fishery income was common (44% of fishers), especially for i-Kiribati fishers, male fishers, and fishers experiencing difficulty selling their catch, but was uncorrelated with sale prices. Income dissatisfaction worsened with age. The number of livelihood activities averaged 2.2–2.5 across countries, and varied significantly among locations. Sea cucumbers were often a primary source of income to fishers, especially in Tonga. Other common livelihood activities were fishing other marine resources, copra production in Kiribati, agriculture in Fiji, and salaried jobs in New Caledonia. Fishing other coastal and coral reef resources was the most common fall-back livelihood option if fishers were forced to exit the fishery. Our data highlight large disparities in subsistence consumption, gender-related price equity, and livelihood diversity among parallel artisanal fisheries. Improvement of supply chains in dispersed small-scale fisheries appears as a critical need for enhancing income and wellbeing of fishers. Strong evidence for co-dependence among small-scale fisheries, through fall-back livelihood preferences of fishers, suggests that resource managers must mitigate concomitant effects on
Relationship between gait initiation and disability in individuals affected by multiple sclerosis.
Galli, Manuela; Coghe, Giancarlo; Sanna, Paola; Cocco, Eleonora; Marrosu, Maria Giovanna; Pau, Massimiliano
2015-11-01
This study analyzes how multiple sclerosis (MS) does affect one of the most common voluntary activities in life: the gait initiation (GI). The main aim of the work is to characterize the execution of this task by measuring and comparing relevant parameters based on center of pressure (COP) patterns and to study the relationship between these and the level of expanded disability status scale (EDSS). To this aim, 95 MS subjects with an average EDSS score of 2.4 and 35 healthy subjects were tested using a force platform during the transition from standing posture to gait. COP time-series were acquired and processed to extract a number of parameters related to the trajectory followed by the COP. The statistical analysis revealed that only a few measurements were statistically different between the two groups and only these were subsequently correlated with EDSS score. The correlation analysis underlined that a progressive alteration of the task execution can be directly related with the increase of EDSS score. These finding suggest that most of the impairment found in people with MS comes from the first part of the COP pattern, the anticipatory postural adjustments (APAs). The central nervous system performs APAs before every voluntary movement to minimize balance perturbation due to the movement itself. Gait Initiation's APAs consist in some ankle muscles contractions that induce a backward COP shift to the swing limb. The analysis here performed highlighted that MS affected patients have a reduced posterior COP shift that reveals that the anticipatory mechanism is impaired. Copyright © 2015 Elsevier B.V. All rights reserved.
Multiple Sclerosis-related Uveitis: Does MS Treatment Affect Uveitis Course?
Jouve, Léa; Benrabah, Rabah; Héron, Emmanuel; Bodaghi, Bahram; Le Hoang, Phuc; Touitou, Valérie
2017-06-01
Few data are available regarding the optimal treatment of multiple sclerosis (MS)-related uveitis. The aim of this study was to describe clinical features of MS-associated uveitis and determine how MS treatment affects the course of uveitis. Retrospective, multicenter study. Patients were divided into two groups according to the use (group 2) or not (group 1) of immunomodulatory drugs. Characteristics of uveitis and treatment were reviewed. A total of 68 eyes from 36 patients (17 in group 1 and 19 in group 2) were included. All patients were treated with topical and/or systemic steroids for uveitis. Uveitis occurred 1-17 years prior to neurologic symptoms in 78% of patients. Uveitis was more severe in group 2 (puveitis (p = 0.06). MS-related uveitis has often a favorable evolution. Patients on interferon-beta have more severe and chronic uveitis. As far as we are concerned, interferon-beta given on the sole indication of uveitis is not recommended. If steroid-sparing agent is required for intraocular inflammation, immunosuppressive drugs should be considered.
Deficiency of RITA results in multiple mitotic defects by affecting microtubule dynamics.
Steinhäuser, K; Klöble, P; Kreis, N-N; Ritter, A; Friemel, A; Roth, S; Reichel, J M; Michaelis, J; Rieger, M A; Louwen, F; Oswald, F; Yuan, J
2017-04-01
Deregulation of mitotic microtubule (MT) dynamics results in defective spindle assembly and chromosome missegregation, leading further to chromosome instability, a hallmark of tumor cells. RBP-J interacting and tubulin-associated protein (RITA) has been identified as a negative regulator of the Notch signaling pathway. Intriguingly, deregulated RITA is involved in primary hepatocellular carcinoma and other malignant entities. We were interested in the potential molecular mechanisms behind its involvement. We show here that RITA binds to tubulin and localizes to various mitotic MT structures. RITA coats MTs and affects their structures in vitro as well as in vivo. Tumor cell lines deficient of RITA display increased acetylated α-tubulin, enhanced MT stability and reduced MT dynamics, accompanied by multiple mitotic defects, including chromosome misalignment and segregation errors. Re-expression of wild-type RITA, but not RITA Δtub ineffectively binding to tubulin, restores the phenotypes, suggesting that the role of RITA in MT modulation is mediated via its interaction with tubulin. Mechanistically, RITA interacts with tubulin/histone deacetylase 6 (HDAC6) and its suppression decreases the binding of the deacetylase HDAC6 to tubulin/MTs. Furthermore, the mitotic defects and increased MT stability are also observed in RITA -/- mouse embryonic fibroblasts. RITA has thus a novel role in modulating MT dynamics and its deregulation results in erroneous chromosome segregation, one of the major reasons for chromosome instability in tumor cells.
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
International Nuclear Information System (INIS)
Dedonder, J.-P.
1979-01-01
This work is devoted to the study of elastic hadron nucleus scattering. At first, an asymptotic evaluation leads to a closed, analytic expression of the eikonal amplitude. This approximate expression displays the role and the influence of the nuclear paremeters in, e.g., p-nucleus scattering around 1 GeV. Pion-nucleus scattering around the 3-3 resonance is then studied. A 3 body model calculation (pion, bound nucleon and residual nucleus represented by a potential) allows to study the importance of binding effects in this problem dominated by the strong energy dependence of the elementary amplitude. The last part is devoted to the construction in momentum space of a realistic optical potential and its comparison with experimental data. The scalling of π + and π - on neighbouring isotopes should allow the measure of the differences between the proton and neutron distributions in nuclei [fr
International Nuclear Information System (INIS)
Orecchini, A; Paciaroni, A; Petrillo, C; Sebastiani, F; Sacchetti, F; De Francesco, A
2012-01-01
The dynamics of water as subtly perturbed by both the interaction with biomolecules and the variation of temperature and pressure has been investigated via neutron scattering spectroscopy. A measurement of inelastic neutron scattering devoted to the study of the coherent THz dynamics of water in a water-rich mixture with DNA (hydration level of 1 g DNA/15 g D 2 O) at room temperature is reported. The DNA hydration water coherent dynamics is characterised by the presence of collective modes, whose dispersion relations are similar to those observed in bulk water. These dispersion relations are well described by the interaction model developed in the case of bulk water, and the existence of a fast sound is experimentally demonstrated. The behaviour of the collective water dynamics was complemented by studying the single-particle dynamics of bulk water along the isotherm T = 298 K in the pressure range 0.1-350 MPa by means of incoherent scattering. This experiment is an attempt to simulate the change of the water molecular arrangement due to the interaction with DNA, by increasing the pressure as the presence of the biomolecule produces an increase in the density. An anomaly is found in the behaviour of the relaxation time derived from the quasi-elastic scattering signal, which can be related to the hypothetical second critical point in water. This anomaly and the transition from slow to fast sound take place in the same Q range, thus suggesting that the two phenomena could be related at some microscopic level.
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
Ikegami, Seiji
2017-09-01
The switching model (PSM) developed in the previous paper is extended to obtain an ;extended switching model (ESM). In the ESM, the mixt electronic-and-nuclear energy-loss region, in addition to the electronic and nuclear energy-loss regions in PSM, is taken into account analytically and appropriately. This model is combined with a small-angle multiple scattering range theory considering both nuclear and electronic stopping effects developed by Marwick-Sigmund and Valdes-Arista to formulate a improved range theory. The ESM is also combined with the multiple scattering theory with non-small angle approximation by Goudsmit-Saunderson. Furthermore, we applied ESM to lateral spread model of Marwick-Sigmund. Numerical calculations of the entire distribution functions including one of the mixt region are roughly and approximately possible. However, exact numerical calculation may be impossible. Consequently, several preliminary numerical calculations of the electronic, mixt, and nuclear regions are performed to examine their underlying behavior with respect to the incident energy, the scattering angle, the outgoing projectile intensity, and the target thickness. We show the numerical results not only of PSM and but also of ESM. Both numerical results are shown in the present paper for the first time. Since the theoretical relations are constructed using reduced variables, the calculations are made only on the case of C colliding on C.
Hesford, Andrew J; Astheimer, Jeffrey P; Greengard, Leslie F; Waag, Robert C
2010-02-01
A multiple-scattering approach is presented to compute the solution of the Helmholtz equation when a number of spherical scatterers are nested in the interior of an acoustically large enclosing sphere. The solution is represented in terms of partial-wave expansions, and a linear system of equations is derived to enforce continuity of pressure and normal particle velocity across all material interfaces. This approach yields high-order accuracy and avoids some of the difficulties encountered when using integral equations that apply to surfaces of arbitrary shape. Calculations are accelerated by using diagonal translation operators to compute the interactions between spheres when the operators are numerically stable. Numerical results are presented to demonstrate the accuracy and efficiency of the method.
Energy Technology Data Exchange (ETDEWEB)
Blazhevich, S. V.; Kos’kova, T. V.; Noskov, A. V., E-mail: noskovbupk@mail.ru [Belgorod State National Research University (Russian Federation)
2016-01-15
A dynamic theory of coherent X-ray radiation generated in a periodic layered medium by a relativistic electron multiply scattered by target atoms has been developed. The expressions describing the spectral–angular characteristics of parametric X-ray radiation and diffracted transition radiation are derived. Numerical calculations based on the derived expressions have been performed.
Lohmueller, Kirk E; Albrechtsen, Anders; Li, Yingrui; Kim, Su Yeon; Korneliussen, Thorfinn; Vinckenbosch, Nicolas; Tian, Geng; Huerta-Sanchez, Emilia; Feder, Alison F; Grarup, Niels; Jørgensen, Torben; Jiang, Tao; Witte, Daniel R; Sandbæk, Annelli; Hellmann, Ines; Lauritzen, Torsten; Hansen, Torben; Pedersen, Oluf; Wang, Jun; Nielsen, Rasmus
2011-10-01
A major question in evolutionary biology is how natural selection has shaped patterns of genetic variation across the human genome. Previous work has documented a reduction in genetic diversity in regions of the genome with low recombination rates. However, it is unclear whether other summaries of genetic variation, like allele frequencies, are also correlated with recombination rate and whether these correlations can be explained solely by negative selection against deleterious mutations or whether positive selection acting on favorable alleles is also required. Here we attempt to address these questions by analyzing three different genome-wide resequencing datasets from European individuals. We document several significant correlations between different genomic features. In particular, we find that average minor allele frequency and diversity are reduced in regions of low recombination and that human diversity, human-chimp divergence, and average minor allele frequency are reduced near genes. Population genetic simulations show that either positive natural selection acting on favorable mutations or negative natural selection acting against deleterious mutations can explain these correlations. However, models with strong positive selection on nonsynonymous mutations and little negative selection predict a stronger negative correlation between neutral diversity and nonsynonymous divergence than observed in the actual data, supporting the importance of negative, rather than positive, selection throughout the genome. Further, we show that the widespread presence of weakly deleterious alleles, rather than a small number of strongly positively selected mutations, is responsible for the correlation between neutral genetic diversity and recombination rate. This work suggests that natural selection has affected multiple aspects of linked neutral variation throughout the human genome and that positive selection is not required to explain these observations.
The interplay of multiple sclerosis and menstrual cycle: Which one affects the other one?
Mirmosayyeb, Omid; Badihian, Shervin; Manouchehri, Navid; Basiri, Akram Kahid; Barzegar, Mahdi; Esmaeil, Nafiseh; Fayyazi, Emad; Shaygannejad, Vahid
2018-02-02
Menstruation is suggested to affect multiple sclerosis (MS) symptoms, while the effect of MS on menstruation is not studied before. Here, we aimed to compare the pattern of menstrual cycle and its symptoms between MS patients and healthy controls. This is a cross-sectional study conducted during 2015-2016 in MS clinic of Kashani hospital, Isfahan, Iran. We included female patients > 14 years with diagnosis of relapsing-remitting MS, and healthy subjects as the control group. We collected data regarding menarche age, menstrual characteristics, history of premenstrual syndrome, the amount of menstrual bleeding, and the possible perimenstrual symptoms from all subjects. Also, MS patients were asked to report changes in menstrual characteristics after MS occurrence. The final study population contained 181 MS patients and 202 healthy subjects. The mean age in MS and control group were 36.04 ± 9.86 and 35.16 ± 11.30, respectively (P-value = 0.426). Menarche age in MS patients and control group were not statistically different (13.59 ± 1.87 and 13.29 ± 1.53, respectively; P-value = 0.087). Changing menstrual characteristics was reported in 70 MS patients (38.7%). Irregular menstrual cycle increased from 21% to 40.3% after occurrence of MS (P-value < 0.001) and was reported 24.7% in the control group. MS patients versus controls reported more symptoms before, during, and after their menstrual period (P-values < 0.001). We found no difference regarding menstrual characteristics in MS patients before onset of the disease and healthy controls. Irregular menstrual cycle was observed more after the disease occurrence while other menstrual characteristics did not change. Moreover, MS patients reported many more perimenstrual symptoms. Copyright © 2018. Published by Elsevier B.V.
International Nuclear Information System (INIS)
Canpolat, M.; Mourant, J.R.
2000-01-01
Measurement of light transport in tissue has the potential to be an inexpensive and practical tool for non-invasive tissue diagnosis in medical applications because it can provide information on both morphological and biochemical properties. To capitalize on the potential of light transport as a diagnostic tool, an understanding of what information can be gleaned from light transport measurements is needed. We present data concerning the sensitivity of light transport measurements, made in clinically relevant geometries, to scattering properties. The intensity of the backscattered light at small source-detector separations is shown to be sensitive to the phase function, and furthermore the collected light intensity is found to be correlated with the amount of high-angle scattering in the medium. (author)
Talamo, Giampaolo P; Ibrahim, Sulfi; Claxton, David; Tricot, Guido J; Fink, Louis M; Zangari, Maurizio
2009-07-01
The therapeutic use of thalidomide in patients with multiple myeloma is often complicated by the development of venous thromboembolism. The objective of the present study was to identify hypercoagulable states associated with development of venous thromboembolism in thalidomide-treated multiple myeloma patients. We screened 49 consecutive multiple myeloma patients treated with thalidomide at baseline for hypercoagulability. With a median follow-up of 11 months, 10 of 49 multiple myeloma patients developed a thrombotic episode. Laboratory assays revealed an underlying abnormality in nine of the 10 patients; hypercoagulable screenings were normal in 36 of the 39 patients who did not develop venous thromboembolism (P < 0.0001). Our retrospective study results suggest that the multiple myeloma patients with thromboembolic complications during treatment with thalidomide have a frequent concomitant underlying thrombophilic state.
International Nuclear Information System (INIS)
Bhattacharya, S.
1989-01-01
The role of the leading particles in high energy scattering phenomena has assumed much importance in recent times but it has not been duly considered in some theoretical studies. This oversight is pointed out, and some other shortcomings and insufficiencies of most of the contemporary theoretical studies not only from considerations of the leading particle effect (LPE) but also from some other viewpoints are mentio ned. A revised comparative study on the behaviour of the average multiplicity by taking into account some of the competing theoretical models and the influence of the leading particle effect on them is also presented. (author). 33 refs
Stamnes, Knut; Tsay, S.-CHEE; Jayaweera, Kolf; Wiscombe, Warren
1988-01-01
The transfer of monochromatic radiation in a scattering, absorbing, and emitting plane-parallel medium with a specified bidirectional reflectivity at the lower boundary is considered. The equations and boundary conditions are summarized. The numerical implementation of the theory is discussed with attention given to the reliable and efficient computation of eigenvalues and eigenvectors. Ways of avoiding fatal overflows and ill-conditioning in the matrix inversion needed to determine the integration constants are also presented.
Cetinic, M.; Diamanti, J.; Szeman, I.; Blacker, S.; Sully, J.
2017-01-01
This chapter historicizes four divergent but historically contemporaneous genres of affect theory – romantic, realist, speculative, and materialist. While critics credited with the turn to affect in the 1990s wrote largely in the wake of poststructuralism from the perspective of gender and queer
International Nuclear Information System (INIS)
Sun Zhihu; Wei Shiqiang; Kolobov, A.V.; Oyanagi, H.; Brunner, K.
2005-01-01
Multiple-scattering extended x-ray absorption fine structure (MS-EXAFS) has been used to investigate the local structures around Ge atoms in self-assembled Ge-Si quantum dots (QDs) grown on Si(001) substrate. The MS effect of Ge QDs is dominated by the scattering path Ge 0 →B 1 →B 2 →Ge 0 (DS2), which contributes a signal destructively interfering with that of the second shell single-scattering path (SS2). MS-EXAFS analysis reveals that the degree of Ge-Si intermixing for Ge-Si QDs strongly depends on the temperature at which the silicon cap layer is overgrown. It is found that the interatomic distances (R Ge-Ge and R Ge-Si ) within the third nearest-neighbor shells in Ge-Si QDs indicate the compressively strained nature of QDs. The present study demonstrates that the MS-EXAFS provides detailed information on the QDs strain and the Ge-Si mixing beyond the nearest neighbors
Iguchi, Toshio; Meneghini, Robert
1993-01-01
Air-borne radar measurements of thunderstorms were made as part of the CaPE (Convection and Precipitation/Electrification) experiment in Florida in July 1991. The radar has two channels, X-band (10 GHz) and Ka-band (34.5 GHz), and is capable of measuring cross-polarized returns as well as co-polarized returns. In stratiform rain, the cross-polarized components can be observed only at the bright band region and from the surface reflection. The linear depolarization ratios (LDR's) measured at X-band and Ka-band at the bright band are nearly equal. In convective rain, however, the LDR in Ka-band often exceeds the X-band LDR by several dB, and sometimes by more than 10 dB, reaching LDR values of up to -5 dB over heavy convective rain. For randomly oriented hydrometeors, such high LDR values cannot be explained by single scattering from non-spherical scattering particles alone. Because the LDR by single backscatter depends weakly on the wavelength, the difference between the Ka-band and X-band LDR's suggests that multiple scattering effects prevail in the Ka-band LDR. In order to test this inference, the magnitude of the cross-polarized component created by double scattering was calculated using the parameters of the airborne radar, which for both frequencies has beamwidths of 5.1 degrees and pulse widths of 0.5 microsecond. Uniform rain beyond the range of 3 km is assumed.
Study of multiple hard-scatter processes from different p p interactions in the same ATLAS event
The ATLAS collaboration
2018-01-01
Given the large integrated luminosity and the large average pileup in the 2017 ATLAS dataset, the probability of having two leptonically decaying Z bosons originating from separate $pp$ interactions in the same LHC bunch crossing becomes non-negligible. Such events are searched for and the number observed compared with the expectation. These types of events (also for the case involving other hard scatter processes, such as W, photon or top quark production, in the same event) may cause additional backgrounds for particular physics analyses, and therefore this background must be accounted for when relevant.
Nicolaou, Mihalis A.; Gunes, Hatice; Pantic, Maja
Past research in analysis of human affect has focused on recognition of prototypic expressions of six basic emotions based on posed data acquired in laboratory settings. Recently, there has been a shift toward subtle, continuous, and context-specific interpretations of affective displays recorded in
Priming in concert: Assimilation and contrast with multiple affective and gender primes.
Fockenberg, D.A.; Koole, S.L.; Semin, G.R.
2008-01-01
The present research investigated the influence of multiple sequential primes on social categorization processes. Study 1 examined an evaluative decision task in which targets were preceded and succeeded by two primes. As expected, the temporally closest forward primes had assimilative effects on
Steven P. Norman; Danny C. Lee; Sandra Jacobson; Christine Damiani
2010-01-01
The tradeoffs that surround forest management are inherently complex, often involving multiple temporal and spatial scales. For example, conflicts may result when fuel treatments are designed to mediate long-term fuel hazards, but activities could impair sensitive aquatic habitat or degrade wildlife habitat in the short term. This complexity makes it hard for managers...
D'hooghe, M. B.; D'Hooghe, T.; De Keyser, J.
2013-01-01
Multiple sclerosis (MS), a chronic inflammatory demyelinating and degenerative disease of the central nervous system, is a frequent cause of neurological disability in young adults. Female predominance has increased over the last decades. Although female gender carries a higher risk of developing
Directory of Open Access Journals (Sweden)
Shahnaz Shahrbanian
2013-01-01
Full Text Available BACKGROUND: Individuals with multiple sclerosis (MS experience some of the highest unemployment rates among all groups of chronic illnesses. Pain has been found to be a common reason for sick leave or early retirement in healthy populations or other groups with chronic illness; however, there is little awareness regarding the effect of pain on the work status of individuals with MS.
International Nuclear Information System (INIS)
Kawano, Shinji; Fukui, Susumu; Moriai, Atsushi; Ohtomo, Akitoshi; Ichimura, Shigeki; Onodera, Akifumi; Amita, F.; Katano, Susumu
1998-01-01
We have developed unique system available for controlling sample environment during the neutron scattering experiments. The system can simultaneously generate triple extreme conditions of low temperature, high magnetic field and high pressure. The system consists of: (i) a liquid-helium cryostat variable for sample temperature from 1.7 K to 200 K, (ii) a superconducting magnet providing a vertical field up to ±5 T with an antisymmetric split-coil geometry for polarized-beam experiments, and (iii) a non-magnetic piston-cylinder high-pressure cell designed with the aim of generating hydrostatic pressure up to 2.5 GPa. In the presentation, we will report the outline of the system and some results of performance tests at KURRI and JRR-3M of JAERI. (author)
Use of multiple methods to determine factors affecting quality of care of patients with diabetes.
Khunti, K
1999-10-01
The process of care of patients with diabetes is complex; however, GPs are playing a greater role in its management. Despite the research evidence, the quality of care of patients with diabetes is variable. In order to improve care, information is required on the obstacles faced by practices in improving care. Qualitative and quantitative methods can be used for formation of hypotheses and the development of survey procedures. However, to date few examples exist in general practice research on the use of multiple methods using both quantitative and qualitative techniques for hypothesis generation. We aimed to determine information on all factors that may be associated with delivery of care to patients with diabetes. Factors for consideration on delivery of diabetes care were generated by multiple qualitative methods including brainstorming with health professionals and patients, a focus group and interviews with key informants which included GPs and practice nurses. Audit data showing variations in care of patients with diabetes were used to stimulate the brainstorming session. A systematic literature search focusing on quality of care of patients with diabetes in primary care was also conducted. Fifty-four potential factors were identified by multiple methods. Twenty (37.0%) were practice-related factors, 14 (25.9%) were patient-related factors and 20 (37.0%) were organizational factors. A combination of brainstorming and the literature review identified 51 (94.4%) factors. Patients did not identify factors in addition to those identified by other methods. The complexity of delivery of care to patients with diabetes is reflected in the large number of potential factors identified in this study. This study shows the feasibility of using multiple methods for hypothesis generation. Each evaluation method provided unique data which could not otherwise be easily obtained. This study highlights a way of combining various traditional methods in an attempt to overcome the
Decision Aids for Multiple-Decision Disease Management as Affected by Weather Input Errors
Many disease management decision support systems (DSS) rely, exclusively or in part, on weather inputs to calculate an indicator for disease hazard. Error in the weather inputs, typically due to forecasting, interpolation or estimation from off-site sources, may affect model calculations and manage...
Uy, Chin; Manalo, Ronaldo A.; Cabauatan, Ronaldo R.
2015-01-01
In the Philippines, students seeking admission to a university are usually required to meet certain entrance requirements, including passing the entrance examinations with questions on IQ and English, mathematics, and science. This paper aims to determine the factors that affect the performance of entrants into business programmes in high-stakes…
Gelling agents and culture vessels affect in vitro multiplication of banana plantlets.
Kaçar, Y A; Biçen, B; Varol, I; Mendi, Y Y; Serçe, S; Cetiner, S
2010-03-09
Agar is the most commonly used gelling agent in media for plant tissue culture. Because of the high price of tissue-culture-grade agar, attempts have been made to identify suitable alternatives. The type of culture vessel and lid also affects the gaseous composition inside the vessel as well as light penetration. In turn, the vessel affects growth parameters, such as shoot elongation, proliferation and fresh weight, as well as hyperhydric degradation processes. We examined the effects of different culture vessels, including commercial glass jars, magenta boxes, and disposable containers, as well as different gelling agents (agar-agar, Agargel, Phytagel, and plant agar) on the micropropagation of Dwarf Cavendish bananas in an effort to find a combination that yields large numbers of high-quality seedlings. The different culture vessels did not significantly affect seedling culture success. The medium significantly affected shoot weight. Phytagel resulted in the highest shoot weight (overall mean = 2.4 g), while agar, Agargel and plant agar resulted in 1.7, 2.2 and 2.2 g, respectively. Disposable container/Phytagel and Magenta/Agargel combinations yielded the highest shoot weights (2.9 and 3.0 g, respectively). Mean shoot length increased progressively with subculture (four subcultures were made). The highest mean shoot length was obtained with Phytagel and Agargel media (6.4 and 6.3 cm, respectively). Shoot number was significantly affected by medium only at subculture 4. Overall, the highest mean shoot length was obtained with the Magenta/Agargel combination (8.5 cm). Phytagel and plant agar gave higher mean shoot number than agar and Agargel (2.1, 2.1 and 1.7 and 1.9, respectively). The costs of the media and of the culture vessels need to be taken into account for final choice of the banana shoot culture system.
1984-05-29
radial distribution and inverse transform of this range. The region commonly used for the inverse transform usually corresponds to the first or second...r-space and comparing it with the corresponding model function. Figure 5 shows the filtered spectra (k weighting), where the pe. 48 allowed inverse ... transform range was successively increased from the radial distance corresponding to the first shell to all the first four shells. There are no multiple
Energy Technology Data Exchange (ETDEWEB)
Cox, A.J.; Warner, P.C.; Findlay, D.J.S.; Cookson, J.A. (eds.)
1986-06-01
Future fusion reactors will use lithium as a blanket material in order to breed tritium. Knowledge of the gamma ray production cross-sections associated with 14 MeV neutron interactions in lithium are therefore important for local heating and biological shielding calculations and neutron energy degradation studies. In the present work, the differential cross-sections have been measured for the production of 0.478 MeV gamma rays following the inelastic scattering of 14 MeV neutrons in large samples of LiF. The neutrons were produced using the /sup 3/H(d,n) /sup 4/He reaction, the deuterons being accelerated by a 150 kV SAMES type accelerator. In order to reduce the background level, the gamma ray signal was gated using a time-of-flight technique based on the alpha particle associated with neutron production. The gamma ray detector was a 3 x 3 inch NaI(T1) scintillator coupled to a 56AVP photomultiplier.
International Nuclear Information System (INIS)
Ziyu Wu; Paris, E.; Langenhorst, F.; Seifert, F.
2002-01-01
The O K-edge spectra of a series of Ti-bearing compounds with Ti in diffrent structural and chemical environments have been measured using electron energy-loss spectroscopy and analyzed using ab initio full multiple-scattering (MS) calculations. The near-edge structures arise mainly from covalency by direct and/or indirect interaction between O and metal atoms and between O and Si atoms. The coordination number of the cation and the site symmetry also influence the spectral shape and structures. Using different size clusters around the excited atom in the full MS simulation, it is possible to interpret and assign the features present in the spectra of each compund to its specific atomic arrangement and electronic structure. (au)
Arteriolosclerosis that affects multiple brain regions is linked to hippocampal sclerosis of ageing.
Neltner, Janna H; Abner, Erin L; Baker, Steven; Schmitt, Frederick A; Kryscio, Richard J; Jicha, Gregory A; Smith, Charles D; Hammack, Eleanor; Kukull, Walter A; Brenowitz, Willa D; Van Eldik, Linda J; Nelson, Peter T
2014-01-01
Hippocampal sclerosis of ageing is a prevalent brain disease that afflicts older persons and has been linked with cerebrovascular pathology. Arteriolosclerosis is a subtype of cerebrovascular pathology characterized by concentrically thickened arterioles. Here we report data from multiple large autopsy series (University of Kentucky Alzheimer's Disease Centre, Nun Study, and National Alzheimer's Coordinating Centre) showing a specific association between hippocampal sclerosis of ageing pathology and arteriolosclerosis. The present analyses incorporate 226 cases of autopsy-proven hippocampal sclerosis of ageing and 1792 controls. Case-control comparisons were performed including digital pathological assessments for detailed analyses of blood vessel morphology. We found no evidence of associations between hippocampal sclerosis of ageing pathology and lacunar infarcts, large infarcts, Circle of Willis atherosclerosis, or cerebral amyloid angiopathy. Individuals with hippocampal sclerosis of ageing pathology did not show increased rates of clinically documented hypertension, diabetes, or other cardiac risk factors. The correlation between arteriolosclerosis and hippocampal sclerosis of ageing pathology was strong in multiple brain regions outside of the hippocampus. For example, the presence of arteriolosclerosis in the frontal cortex (Brodmann area 9) was strongly associated with hippocampal sclerosis of ageing pathology (P studies to optimize immunostaining methods for small blood vessel visualization, our analyses focused on sections immunostained for smooth muscle actin (a marker of arterioles) and CD34 (an endothelial marker), with separate analyses on grey and white matter. A total of 43 834 smooth muscle actin-positive vascular profiles and 603 798 CD34-positive vascular profiles were evaluated. In frontal cortex of cases with hippocampal sclerosis of ageing, smooth muscle actin-immunoreactive arterioles had thicker walls (P < 0.05), larger perimeters (P < 0
Arteriolosclerosis that affects multiple brain regions is linked to hippocampal sclerosis of ageing
Neltner, Janna H.; Abner, Erin L.; Baker, Steven; Schmitt, Frederick A.; Kryscio, Richard J.; Jicha, Gregory A.; Smith, Charles D.; Hammack, Eleanor; Kukull, Walter A.; Brenowitz, Willa D.; Van Eldik, Linda J.
2014-01-01
Hippocampal sclerosis of ageing is a prevalent brain disease that afflicts older persons and has been linked with cerebrovascular pathology. Arteriolosclerosis is a subtype of cerebrovascular pathology characterized by concentrically thickened arterioles. Here we report data from multiple large autopsy series (University of Kentucky Alzheimer’s Disease Centre, Nun Study, and National Alzheimer’s Coordinating Centre) showing a specific association between hippocampal sclerosis of ageing pathology and arteriolosclerosis. The present analyses incorporate 226 cases of autopsy-proven hippocampal sclerosis of ageing and 1792 controls. Case–control comparisons were performed including digital pathological assessments for detailed analyses of blood vessel morphology. We found no evidence of associations between hippocampal sclerosis of ageing pathology and lacunar infarcts, large infarcts, Circle of Willis atherosclerosis, or cerebral amyloid angiopathy. Individuals with hippocampal sclerosis of ageing pathology did not show increased rates of clinically documented hypertension, diabetes, or other cardiac risk factors. The correlation between arteriolosclerosis and hippocampal sclerosis of ageing pathology was strong in multiple brain regions outside of the hippocampus. For example, the presence of arteriolosclerosis in the frontal cortex (Brodmann area 9) was strongly associated with hippocampal sclerosis of ageing pathology (P ageing (n = 15) and control (n = 42) cases. Following technical studies to optimize immunostaining methods for small blood vessel visualization, our analyses focused on sections immunostained for smooth muscle actin (a marker of arterioles) and CD34 (an endothelial marker), with separate analyses on grey and white matter. A total of 43 834 smooth muscle actin-positive vascular profiles and 603 798 CD34-positive vascular profiles were evaluated. In frontal cortex of cases with hippocampal sclerosis of ageing, smooth muscle actin
Quantification of chemical elements in blood of patients affected by multiple sclerosis.
Forte, Giovanni; Visconti, Andrea; Santucci, Simone; Ghazaryan, Anna; Figà-Talamanca, Lorenzo; Cannoni, Stefania; Bocca, Beatrice; Pino, Anna; Violante, Nicola; Alimonti, Alessandro; Salvetti, Marco; Ristori, Giovanni
2005-01-01
Although some studies suggested a link between exposure to trace elements and development of multiple sclerosis (MS), clear information on their role in the aetiology of MS is still lacking. In this study the concentrations of Al, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Ni, Pb, Sb, Si, Sn, Sr, Tl, V, W, Zn and Zr were determined in the blood of 60 patients with MS and 60 controls. Quantifications were performed by inductively coupled plasma (ICP) atomic emission spectrometry and sector field ICP mass spectrometry. When the two groups were compared, an increased level of Co, Cu and Ni and a decrement of Be, Fe, Hg, Mg, Mo, Pb and Zn in blood of patients were observed. In addition, the discriminant analysis pointed out that Cu, Be, Hg, Co and Mo were able to discriminate between MS patients and controls (92.5% of cases correctly classified).
DEFF Research Database (Denmark)
Nielsen, Kaspar René; Rodrigo-Domingo, Maria; Steffensen, Rudi
2017-01-01
The origin of multiple myeloma depends on interactions with stromal cells in the course of normal B-cell differentiation and evolution of immunity. The concept of the present study is that genes involved in MM pathogenesis, such as immune response genes, can be identified by screening for single......3L1 gene promoters. The occurrence of single polymorphisms, haplotypes and SNP-SNP interactions were statistically analyzed for association with disease risk and outcome following high-dose therapy. Identified genes that carried SNPs or haplotypes that were identified as risk or prognostic factors......= .005). The 'risk genes' were analyzed for expression in normal B-cell subsets (N = 6) from seven healthy donors and we found TNFA and IL-6 expressed both in naïve and in memory B cells when compared to preBI, II, immature and plasma cells. The 'prognosis genes' CHI3L1, IL-6 and IL-10 were differential...
Position Affects Performance in Multiple-Object Tracking in Rugby Union Players
Directory of Open Access Journals (Sweden)
Andrés Martín
2017-09-01
Full Text Available We report an experiment that examines the performance of rugby union players and a control group composed of graduate student with no sport experience, in a multiple-object tracking task. It compares the ability of 86 high level rugby union players grouped as Backs and Forwards and the control group, to track a subset of randomly moving targets amongst the same number of distractors. Several difficulties were included in the experimental design in order to evaluate possible interactions between the relevant variables. Results show that the performance of the Backs is better than that of the other groups, but the occurrence of interactions precludes an isolated groups analysis. We interpret the results within the framework of visual attention and discuss both, the implications of our results and the practical consequences.
Directory of Open Access Journals (Sweden)
Danielle Cosme
Full Text Available As a form of attention, mindfulness is qualitatively receptive and non-reactive, and is thought to facilitate adaptive emotional responding. One suggested mechanism is that mindfulness facilitates disengagement from an affective stimulus and thereby decreases affective reactivity. However, mindfulness has been conceptualized as a state, intervention, and trait. Because evidence is mixed as to whether self-reported trait mindfulness decreases affective reactivity, we used a multi-method approach to study the relationship between individual differences in self-reported trait mindfulness and electrocortical, electrodermal, electromyographic, and self-reported responses to emotional pictures. Specifically, while participants (N = 51 passively viewed pleasant, neutral, and unpleasant IAPS pictures, we recorded high-density (128 channels electrocortical, electrodermal, and electromyographic data to the pictures as well as to acoustic startle probes presented during the pictures. Afterwards, participants rated their subjective valence and arousal while viewing the pictures again. If trait mindfulness spontaneously reduces general emotional reactivity, then for individuals reporting high rather than low mindfulness, response differences between emotional and neutral pictures would show relatively decreased early posterior negativity (EPN and late positive potential (LPP amplitudes, decreased skin conductance responses, and decreased subjective ratings for valence and arousal. High mindfulness would also be associated with decreased emotional modulation of startle eyeblink and P3 amplitudes. Although results showed clear effects of emotion on the dependent measures, in general, mindfulness did not moderate these effects. For most measures, effect sizes were small with rather narrow confidence intervals. These data do not support the hypothesis that individual differences in self-reported trait mindfulness are related to spontaneous emotional responses
Cosme, Danielle; Wiens, Stefan
2015-01-01
As a form of attention, mindfulness is qualitatively receptive and non-reactive, and is thought to facilitate adaptive emotional responding. One suggested mechanism is that mindfulness facilitates disengagement from an affective stimulus and thereby decreases affective reactivity. However, mindfulness has been conceptualized as a state, intervention, and trait. Because evidence is mixed as to whether self-reported trait mindfulness decreases affective reactivity, we used a multi-method approach to study the relationship between individual differences in self-reported trait mindfulness and electrocortical, electrodermal, electromyographic, and self-reported responses to emotional pictures. Specifically, while participants (N = 51) passively viewed pleasant, neutral, and unpleasant IAPS pictures, we recorded high-density (128 channels) electrocortical, electrodermal, and electromyographic data to the pictures as well as to acoustic startle probes presented during the pictures. Afterwards, participants rated their subjective valence and arousal while viewing the pictures again. If trait mindfulness spontaneously reduces general emotional reactivity, then for individuals reporting high rather than low mindfulness, response differences between emotional and neutral pictures would show relatively decreased early posterior negativity (EPN) and late positive potential (LPP) amplitudes, decreased skin conductance responses, and decreased subjective ratings for valence and arousal. High mindfulness would also be associated with decreased emotional modulation of startle eyeblink and P3 amplitudes. Although results showed clear effects of emotion on the dependent measures, in general, mindfulness did not moderate these effects. For most measures, effect sizes were small with rather narrow confidence intervals. These data do not support the hypothesis that individual differences in self-reported trait mindfulness are related to spontaneous emotional responses during picture
Do multiple fires interact to affect vegetation structure in temperate eucalypt forests?
Haslem, Angie; Leonard, Steve W J; Bruce, Matthew J; Christie, Fiona; Holland, Greg J; Kelly, Luke T; MacHunter, Josephine; Bennett, Andrew F; Clarke, Michael F; York, Alan
2016-12-01
Fire plays an important role in structuring vegetation in fire-prone regions worldwide. Progress has been made towards documenting the effects of individual fire events and fire regimes on vegetation structure; less is known of how different fire history attributes (e.g., time since fire, fire frequency) interact to affect vegetation. Using the temperate eucalypt foothill forests of southeastern Australia as a case study system, we examine two hypotheses about such interactions: (1) post-fire vegetation succession (e.g., time-since-fire effects) is influenced by other fire regime attributes and (2) the severity of the most recent fire overrides the effect of preceding fires on vegetation structure. Empirical data on vegetation structure were collected from 540 sites distributed across central and eastern Victoria, Australia. Linear mixed models were used to examine these hypotheses and determine the relative influence of fire and environmental attributes on vegetation structure. Fire history measures, particularly time since fire, affected several vegetation attributes including ground and canopy strata; others such as low and sub-canopy vegetation were more strongly influenced by environmental characteristics like rainfall. There was little support for the hypothesis that post-fire succession is influenced by fire history attributes other than time since fire; only canopy regeneration was influenced by another variable (fire type, representing severity). Our capacity to detect an overriding effect of the severity of the most recent fire was limited by a consistently weak effect of preceding fires on vegetation structure. Overall, results suggest the primary way that fire affects vegetation structure in foothill forests is via attributes of the most recent fire, both its severity and time since its occurrence; other attributes of fire regimes (e.g., fire interval, frequency) have less influence. The strong effect of environmental drivers, such as rainfall and
Decision aids for multiple-decision disease management as affected by weather input errors.
Pfender, W F; Gent, D H; Mahaffee, W F; Coop, L B; Fox, A D
2011-06-01
Many disease management decision support systems (DSSs) rely, exclusively or in part, on weather inputs to calculate an indicator for disease hazard. Error in the weather inputs, typically due to forecasting, interpolation, or estimation from off-site sources, may affect model calculations and management decision recommendations. The extent to which errors in weather inputs affect the quality of the final management outcome depends on a number of aspects of the disease management context, including whether management consists of a single dichotomous decision, or of a multi-decision process extending over the cropping season(s). Decision aids for multi-decision disease management typically are based on simple or complex algorithms of weather data which may be accumulated over several days or weeks. It is difficult to quantify accuracy of multi-decision DSSs due to temporally overlapping disease events, existence of more than one solution to optimizing the outcome, opportunities to take later recourse to modify earlier decisions, and the ongoing, complex decision process in which the DSS is only one component. One approach to assessing importance of weather input errors is to conduct an error analysis in which the DSS outcome from high-quality weather data is compared with that from weather data with various levels of bias and/or variance from the original data. We illustrate this analytical approach for two types of DSS, an infection risk index for hop powdery mildew and a simulation model for grass stem rust. Further exploration of analysis methods is needed to address problems associated with assessing uncertainty in multi-decision DSSs.
Kirk-Brown, A K; Van Dijk, P A; Simmons, R D; Bourne, M P; Cooper, B K
2014-06-01
For many employees with multiple sclerosis (MS), disclosure of their diagnosis at work is seen as a high-risk strategy that might lead to diminished perceptions of their capabilities by supervisors and colleagues, if not outright discrimination. The consequence of this mistrust surrounding the disclosure process is that employees with MS may leave it until too late to effectively manage symptoms at work. The objective of this paper is to statistically evaluate the relationship between disclosure of diagnosis at work and maintenance of employment. Three annual, large-sample self-report surveys of MS patients prospectively examined the relationship between disclosure of diagnosis at work and employment status. A total of 1438 people responded to all three surveys. Of employed persons in 2010 (n = 946), 673 also responded to the 2012 survey. Of these 673 respondents 564 were still employed. People who had disclosed their MS status to an employer were more likely to remain in employment in Year 3. The effect of disclosure in predicting employment status remained after controlling for age, gender, hours worked and level of disability. This study provides the first empirical support for the positive role of disclosure in maintaining employment status, measured both as job retention and tenure in current employment. © The Author(s) 2013.
Small Molecules Affect Human Dental Pulp Stem Cell Properties Via Multiple Signaling Pathways
Al-Habib, Mey; Yu, Zongdong
2013-01-01
One fundamental issue regarding stem cells for regenerative medicine is the maintenance of stem cell stemness. The purpose of the study was to test whether small molecules can enhance stem cell properties of mesenchymal stem cells (MSCs) derived from human dental pulp (hDPSCs), which have potential for multiple clinical applications. We identified the effects of small molecules (Pluripotin (SC1), 6-bromoindirubin-3-oxime and rapamycin) on the maintenance of hDPSC properties in vitro and the mechanisms involved in exerting the effects. Primary cultures of hDPSCs were exposed to optimal concentrations of these small molecules. Treated hDPSCs were analyzed for their proliferation, the expression levels of pluripotent and MSC markers, differentiation capacities, and intracellular signaling activations. We found that small molecule treatments decreased cell proliferation and increased the expression of STRO-1, NANOG, OCT4, and SOX2, while diminishing cell differentiation into odonto/osteogenic, adipogenic, and neurogenic lineages in vitro. These effects involved Ras-GAP-, ERK1/2-, and mTOR-signaling pathways, which may preserve the cell self-renewal capacity, while suppressing differentiation. We conclude that small molecules appear to enhance the immature state of hDPSCs in culture, which may be used as a strategy for adult stem cell maintenance and extend their capacity for regenerative applications. PMID:23573877
Does Educator Training or Experience Affect the Quality of Multiple-Choice Questions?
Webb, Emily M; Phuong, Jonathan S; Naeger, David M
2015-10-01
Physicians receive little training on proper multiple-choice question (MCQ) writing methods. Well-constructed MCQs follow rules, which ensure that a question tests what it is intended to test. Questions that break these are described as "flawed." We examined whether the prevalence of flawed questions differed significantly between those with or without prior training in question writing and between those with different levels of educator experience. We assessed 200 unedited MCQs from a question bank for our senior medical student radiology elective: an equal number of questions (50) were written by faculty with previous training in MCQ writing, other faculty, residents, and medical students. Questions were scored independently by two readers for the presence of 11 distinct flaws described in the literature. Questions written by faculty with MCQ writing training had significantly fewer errors: mean 0.4 errors per question compared to a mean of 1.5-1.7 errors per question for the other groups (P Educator experience alone had no effect on the frequency of flaws; faculty without dedicated training, residents, and students performed similarly. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.
Della Puppa, Alessandro; De Pellegrin, Serena; d'Avella, Elena; Gioffrè, Giorgio; Munari, Marina; Saladini, Marina; Salillas, Elena; Scienza, Renato; Semenza, Carlo
2013-11-01
The role of parietal areas in number processing is well known. The significance of intraoperative functional mapping of these areas has been only partially explored, however, and only a few discordant data are available in the surgical literature with regard to the right parietal lobe. The purpose of this study was to evaluate the clinical impact of simple calculation in cortical electrostimulation of right-handed patients affected by a right parietal brain tumor. Calculation mapping in awake surgery was performed in 3 right-handed patients affected by high-grade gliomas located in the right parietal lobe. Preoperatively, none of the patients presented with calculation deficits. In all 3 cases, after sensorimotor and language mapping, cortical and intraparietal sulcus areas involved in single-digit multiplication and addition calculations were mapped using bipolar electrostimulation. In all patients, different sites of the right parietal cortex, mainly in the inferior lobule, were detected as being specifically related to calculation (multiplication or addition). In 2 patients the intraparietal sulcus was functionally specific for multiplication. No functional sites for language were detected. All sites functional for calculation were spared during tumor resection, which was complete in all cases without postoperative neurological deficits. These findings provide intraoperative data in support of an anatomofunctional organization for multiplication and addition within the right parietal area. Furthermore, the study shows the potential clinical relevance of intraoperative mapping of calculation in patients undergoing surgery in the right parietal area. Further and larger studies are needed to confirm these data and assess whether mapped areas are effectively essential for function.
De Wolf, E.A.
2002-01-01
We discuss basic concepts and properties of diffractive phenomena in soft hadron collisions and in deep-inelastic scattering at low Bjorken-x. The paper is not a review of the rapidly developing field but presents an attempt to show in simple terms the close inter-relationship between the dynamics of high-energy hadronic and deep-inelastic diffraction. Using the saturation model of Golec-Biernat and Wusthoff as an example, a simple explanation of geometrical scaling is presented. The relation between the QCD anomalous multiplicity dimension and the Pomeron intercept is discussed.
International Nuclear Information System (INIS)
Wolf, E.A. de
2002-01-01
We discuss basic concepts and properties of diffractive phenomena in soft hadron collisions and in deep-inelastic scattering at low Bjorken - x. The paper is not a review of the rapidly developing field but presents an attempt to show in simple terms the close inter-relationship between the dynamics of high-energy hadronic and deep-inelastic diffraction. Using the saturation model of Golec-Biernat and Wuesthoff as an example, a simple explanation of geometrical scaling is presented. The relation between the QCD anomalous multiplicity dimension and the Pomeron intercept is discussed. (author)
Multiple coronary stenting negatively affects myocardial recovery after coronary bypass grafting.
Yajima, Shin; Yoshioka, Daisuke; Fukushima, Satsuki; Toda, Koichi; Miyagawa, Shigeru; Yoshikawa, Yasushi; Hata, Hiroki; Saito, Shunsuke; Domae, Keitaro; Sawa, Yoshiki
2018-05-14
We aimed to elucidate the relationship between the magnitude of myocardial recovery after coronary artery bypass grafting (CABG) and the prognosis and to explore the predictors of myocardial non-recovery. Eighty-one patients with a preoperative left ventricular ejection fraction (LVEF) ≤ 40% who underwent isolated CABG between 2002 and 2015 and had undergone echocardiographic follow-up (median follow-up, 3.1 years; interquartile range 1.2-6.0 years) were analyzed. The Recovery group comprised patients with LVEF improvement ≥ 10%, whereas the Non-recovery group comprised those with an LVEF improvement events (MACEs), and readmission due to heart failure were evaluated. In addition, the risk factors for LVEF non-recovery were evaluated in a multivariate analysis. A total of 39 patients (48%) were in the Recovery group, whereas 42 patients (52%) were in the Non-recovery group. Although the survival and freedom from MACE rates were comparable, the rate of freedom from heart failure requiring hospitalization at 1, 5, and 8 years of follow-up was significantly lower in the Non-recovery group than in the Recovery group (p = 0.012). A history of percutaneous coronary intervention (PCI) was an exclusive independent risk factor for post-CABG myocardial non-recovery (odds ratio, 16.0; 95% confidence interval, 3.44-125). Furthermore, the number of coronary stents was negatively correlated with LVEF recovery (r = - 0.460, p = 0.024). Great consideration should be taken when performing CABG in patients with left ventricular dysfunction and a history of PCI, particularly in those with multiple coronary stents.
Berry, Kristin H.; Yee, Julie L.; Coble, Ashley A.; Perry, William M.; Shields, Timothy A.
2013-01-01
Numerous factors have contributed to declines in populations of the federally threatened Agassiz's Desert Tortoise (Gopherus agassizii) and continue to limit recovery. In 2010, we surveyed a low-density population on a military test facility in the northwestern Mojave Desert of California, USA, to evaluate population status and identify potential factors contributing to distribution and low densities. Estimated densities of live tortoises ranged spatially from 1.2/km2 to 15.1/km2. Although only one death of a breeding-age tortoise was recorded for the 4-yr period prior to the survey, remains of 16 juvenile and immature tortoises were found, and most showed signs of predation by Common Ravens (Corvus corax) and mammals. Predation may have limited recruitment of young tortoises into the adult size classes. To evaluate the relative importance of different types of impacts to tortoises, we developed predictive models for spatially explicit densities of tortoise sign and live tortoises using topography (i.e., slope), predators (Common Raven, signs of mammalian predators), and anthropogenic impacts (distances from paved road and denuded areas, density of ordnance fragments) as covariates. Models suggest that densities of tortoise sign increased with slope and signs of mammalian predators and decreased with Common Ravens, while also varying based on interaction effects involving these predictors as well as distances from paved roads, denuded areas, and ordnance. Similarly, densities of live tortoises varied by interaction effects among distances to denuded areas and paved roads, density of ordnance fragments, and slope. Thus multiple factors predict the densities and distribution of this population.
Borroni, Giovanni; Vassallo, Camilla; Brazzelli, Valeria; Martinoli, Sara; Ardigò, Marco; Alessandrino, Paolo Emilio; Borroni, Riccardo Giovanni; Franchini, Pietro
2004-06-01
Radiation recall dermatitis is one of the skin sequelae that may affect oncology patients. It occurs in a previously irradiated field, when subsequent chemotherapy is given. The eruption may be elicited by chemotherapy, even several months after radiotherapy. Its mechanism is poorly understood, and the histopathologic findings have received, to date, only sketchy descriptions. A 55-year-old male affected by multiple myeloma received radiation therapy both on his left coxofemoral area, and lumbar region (D11-L1). After cyclophosphamide administration, he developed 2 well defined square-shaped, infiltrated erythematoviolaceous plaques in the prior irradiated fields. Histopathologic findings revealed a diffusely fibrosclerosing process, involving deep dermis, hypodermis, as well as the underlying muscle, while sparing the epidermis and superficial-mid dermis. Histopathology was indistinguishable from deep radio-dermatitis, panniculitis, and myositis. This is the first case providing clear evidence of the causative role of cyclophosphamide in inducing a cutaneous and subcutaneous radiation recall reaction.
Martyniuk, Christopher J.; Spade, Daniel J.; Blum, Jason L.; Kroll, Kevin J.; Denslow, Nancy D.
2011-01-01
Methoxychlor (MXC) is an organochlorine pesticide that has been shown to have estrogenic activity by activating estrogen receptors and inducing vitellogenin production in male fish. Previous studies report that exposure to MXC induces changes in mRNA abundance of reproductive genes in the liver and testes of largemouth bass (Micropterus salmoides). The objective of the present study was to better characterize the mode of action of MXC by measuring the global transcriptomic response in the male largemouth liver using an oligonucleotide microarray. Microarray analysis identified highly significant changes in the expression of 37 transcripts (p<0.001) (20 induced and 17 decreased) in the liver after MXC injection and a total of 900 expression changes (p<0.05) in transcripts with high homology to known genes. Largemouth bass estrogen receptor alpha (esr1) and androgen receptor (ar) were among the transcripts that were increased in the liver after MXC treatment. Functional enrichment analysis identified the molecular functions of steroid binding and androgen receptor activity as well as steroid hormone receptor activity as being significantly over-represented gene ontology terms. Pathway analysis identified c-fos signaling as being putatively affected through both estrogen and androgen signaling. This study provides evidence that MXC elicits transcriptional effects through the estrogen receptor as well as androgen receptor-mediated pathways in the liver. PMID:21276474
Energy Technology Data Exchange (ETDEWEB)
Bluet, J C [Commissariat a l' Energie Atomique, Cadarache (France)
1966-02-01
Three problems of multiple scattering arising from neutron cross sections experiments, are reported here. The common hypothesis are: - Elastic scattering is the only possible process - Angular distributions are isotropic - Losses of particle energy are negligible in successive collisions. In the three cases practical results, corresponding to actual experiments are given. Moreover the results are shown in more general way, using dimensionless variable such as the ratio of geometrical dimensions to neutron mean free path. The FORTRAN codes are given together with to the corresponding flow charts, and lexicons of symbols. First problem: Measurement of sodium capture cross-section. A sodium sample of given geometry is submitted to a neutron flux. Induced activity is then measured by means of a sodium iodide cristal. The distribution of active nuclei in the sample, and the counter efficiency are calculated by Monte-Carlo method taking multiple scattering into account. Second problem: absolute measurement of a neutron flux using a glass scintillator. The scintillator is a use of lithium 6 loaded glass, submitted to neutron flux perpendicular to its plane faces. If the glass thickness is not negligible compared with scattering mean free path {lambda}, the mean path e' of neutrons in the glass is different from the thickness. Monte-Carlo calculation are made to compute this path and a relative correction to efficiency equal to (e' - e)/e. Third problem: study of a neutron collimator. A neutron detector is placed at the bottom of a cylinder surrounded with water. A neutron source is placed on the cylinder axis, in front of the water shield. The number of neutron tracks going directly and indirectly through the water from the source to the detector are counted. (author) [French] On traite dans ce rapport de trois problemes avec les hypotheses communes suivantes: 1.- Le seul processus de collision possible est la diffusion electrique. 2.- La distribution angulaire est
Energy Technology Data Exchange (ETDEWEB)
Lohmander, H
1995-04-01
Charged particle and transverse energy flow for deep inelastic ep scattering at HERA have been investigated in the hadronic center of mass systems as a function of pseudorapidity {eta}* in different W{sup 2} and Q{sup 2} intervals. In addition, the mean charged particle multiplicity
Cui, P. X.; Lian, F. L.; Wang, Y.; Wen, Yi; Chu, W. S.; Zhao, H. F.; Zhang, S.; Li, J.; Lin, D. H.; Wu, Z. Y.
2014-02-01
Prion-related protein (PrP), a cell-surface copper-binding glycoprotein, is considered to be responsible for a number of transmissible spongiform encephalopathies (TSEs). The structural conversion of PrP from the normal cellular isoform (PrPC) to the post-translationally modified form (PrPSc) is thought to be relevant to Cu2+ binding to histidine residues. Rabbits are one of the few mammalian species that appear to be resistant to TSEs, because of the structural characteristics of the rabbit prion protein (RaPrPC) itself. Here we determined the three-dimensional local structure around the C-terminal high-affinity copper-binding sites using X-ray absorption near-edge structure combined with ab initio calculations in the framework of the multiple-scattering (MS) theory. Result shows that two amino acid resides, Gln97 and Met108, and two histidine residues, His95 and His110, are involved in binding this copper(II) ion. It might help us understand the roles of copper in prion conformation conversions, and the molecular mechanisms of prion-involved diseases.
Schemel, L.E.; Cox, M.H.; Runkel, R.L.; Kimball, B.A.
2006-01-01
The acidic discharge from Cement Creek, containing elevated concentrations of dissolved metals and sulphate, mixed with the circumneutral-pH Animas River over a several hundred metre reach (mixing zone) near Silverton, CO, during this study. Differences in concentrations of Ca, Mg, Si, Sr, and SO42- between the creek and the river were sufficiently large for these analytes to be used as natural tracers in the mixing zone. In addition, a sodium chloride (NaCl) tracer was injected into Cement Creek, which provided a Cl- 'reference' tracer in the mixing zone. Conservative transport of the dissolved metals and sulphate through the mixing zone was verified by mass balances and by linear mixing plots relative to the injected reference tracer. At each of seven sites in the mixing zone, five samples were collected at evenly spaced increments of the observed across-channel gradients, as determined by specific conductance. This created sets of samples that adequately covered the ranges of mixtures (mixing ratios, in terms of the fraction of Animas River water, %AR). Concentrations measured in each mixing zone sample and in the upstream Animas River and Cement Creek were used to compute %AR for the reference and natural tracers. Values of %AR from natural tracers generally showed good agreement with values from the reference tracer, but variability in discharge and end-member concentrations and analytical errors contributed to unexpected outlier values for both injected and natural tracers. The median value (MV) %AR (calculated from all of the tracers) reduced scatter in the mixing plots for the dissolved metals, indicating that the MV estimate reduced the effects of various potential errors that could affect any tracer.
Schemel, Laurence E.; Cox, Marisa H.; Runkel, Robert L.; Kimball, Briant A.
2006-08-01
The acidic discharge from Cement Creek, containing elevated concentrations of dissolved metals and sulphate, mixed with the circumneutral-pH Animas River over a several hundred metre reach (mixing zone) near Silverton, CO, during this study. Differences in concentrations of Ca, Mg, Si, Sr, and SO42- between the creek and the river were sufficiently large for these analytes to be used as natural tracers in the mixing zone. In addition, a sodium chloride (NaCl) tracer was injected into Cement Creek, which provided a Cl- reference tracer in the mixing zone. Conservative transport of the dissolved metals and sulphate through the mixing zone was verified by mass balances and by linear mixing plots relative to the injected reference tracer. At each of seven sites in the mixing zone, five samples were collected at evenly spaced increments of the observed across-channel gradients, as determined by specific conductance. This created sets of samples that adequately covered the ranges of mixtures (mixing ratios, in terms of the fraction of Animas River water, %AR). Concentratis measured in each mixing zone sample and in the upstream Animas River and Cement Creek were used to compute %AR for the reference and natural tracers. Values of %AR from natural tracers generally showed good agreement with values from the reference tracer, but variability in discharge and end-member concentrations and analytical errors contributed to unexpected outlier values for both injected and natural tracers. The median value (MV) %AR (calculated from all of the tracers) reduced scatter in the mixing plots for the dissolved metals, indicating that the MV estimate reduced the effects of various potential errors that could affect any tracer.
Uluata, Sibel; McClements, D Julian; Decker, Eric A
2015-02-18
Lipid oxidation is a serious problem for oil-containing food products because it negatively affects shelf life and nutritional composition. An antioxidant strategy commonly employed to prevent or delay oxidation in foods is to remove oxygen from the closed food-packaging system. An alternative technique is use of an edible oxygen scavenger to remove oxygen within the food. Ascorbic acid (AA) is a particularly promising antioxidant because of its natural label and multiple antioxidative functions. In this study, AA was tested as an oxygen scavenger in buffer and an oil-in-water (O/W) emulsion. The effects of transition metals on the ability of AA to scavenge oxygen were determined. Headspace oxygen decrease less than 1% in the medium-chain triacylglycerol (MCT) O/W emulsion system (pH 3 and 7). AA was able to almost completely remove dissolved oxygen (DO) in a buffered solution. Transition metals (Fe(2+) and Cu(+)) significantly accelerated the degradation of AA; however, iron and copper only increased DO depletion rates, by 10.6-16.4% from day 1 to 7, compared to the control. AA (2.5-20 mM) decreased DO in a 1% O/W emulsion system 32.0-64.0% and delayed the formation of headspace hexanal in the emulsion from 7 to over 20 days. This research shows that, when AA is used in an O/W emulsion system, oxidation of the emulsion system can be delay by multiple mechanisms.
Directory of Open Access Journals (Sweden)
Silvia Bianchini
2015-04-01
Full Text Available In recent years, space-borne InSAR (interferometric synthetic aperture radar techniques have shown their capabilities to provide precise measurements of Earth surface displacements for monitoring natural processes. Landslides threaten human lives and structures, especially in urbanized areas, where the density of elements at risk sensitive to ground movements is high. The methodology described in this paper aims at detecting terrain motions and building deformations at the local scale, by means of satellite radar data combined with in situ validation campaigns. The proposed approach consists of deriving maximum settlement directions of the investigated buildings from displacement data revealed by radar measurements and then in the cross-comparison of these values with background geological data, constructive features and on-field evidence. This validation permits better understanding whether or not the detected movements correspond to visible and effective damages to buildings. The method has been applied to the southwestern sector of Volterra (Tuscany region, Italy, which is a landslide-affected and partially urbanized area, through the use of COSMO-SkyMed satellite images as input data. Moreover, we discuss issues and possible misinterpretations when dealing with PSI (Persistent Scatterer Interferometry data referring to single manufactures and the consequent difficulty of attributing the motion rate to ground displacements, rather than to structural failures.
Directory of Open Access Journals (Sweden)
Peter Joseph Jongen
2015-01-01
Full Text Available In persons with multiple sclerosis (MS a lowered self-efficacy negatively affects physical activities. Against this background we studied the relationship between self-efficacy and cognitive performance in the early stages of MS. Thirty-three patients with Clinically Isolated Syndrome (CIS and early Relapsing Remitting MS (eRRMS were assessed for self-efficacy (MSSES-18, cognition (CDR System, fatigue (MFIS-5, depressive symptoms (BDI, disease impact (MSIS-29, and disability (EDSS. Correlative analyses were performed between self-efficacy and cognitive scores, and stepwise regression analyses identified predictors of cognition and self-efficacy. Good correlations existed between total self-efficacy and Power of Attention (r= 0.65; P< 0.001, Reaction Time Variability (r= 0.57; P< 0.001, and Speed of Memory (r= 0.53; P< 0.01, and between control self-efficacy and Reaction Time Variability (r= 0.55; P< 0.01. Total self-efficacy predicted 40% of Power of Attention, 34% of Reaction Time Variability, and 40% of Speed of Memory variabilities. Disease impact predicted 65% of total self-efficacy and 58% of control self-efficacy variabilities. The findings may suggest that in persons with CIS and eRRMS self-efficacy may positively affect cognitive performance and that prevention of disease activity may preserve self-efficacy.
Steponavičius, Raimundas; Thennadil, Suresh N
2011-03-15
The effectiveness of a scatter correction approach based on decoupling absorption and scattering effects through the use of the radiative transfer theory to invert a suitable set of measurements is studied by considering a model multicomponent suspension. The method was used in conjunction with partial least-squares regression to build calibration models for estimating the concentration of two types of analytes: an absorbing (nonscattering) species and a particulate (absorbing and scattering) species. The performances of the models built by this approach were compared with those obtained by applying empirical scatter correction approaches to diffuse reflectance, diffuse transmittance, and collimated transmittance measurements. It was found that the method provided appreciable improvement in model performance for the prediction of both types of analytes. The study indicates that, as long as the bulk absorption spectra are accurately extracted, no further empirical preprocessing to remove light scattering effects is required.
International Nuclear Information System (INIS)
Vorbrugg, W.; Schaerpf, O.
1975-01-01
The small-angle scattering of Ni single crystals with (111) and (100) axis orientation is measured by a photographic method in the work-hardened state after tensile deformation. Parameters are the external magnetic field H parallel to the axis (600 2 ]<=8,8), and the elastic stress tausub(el)(0<=tausub(el)<=tausub(pl)) applied to the deformed crystals during the experiments. The scattering is found to be anisotropic and characteristic for the chosen orientation. The quantitative photometric analysis shows that the parameters mentioned above only influence the intensity but not the distribution of the scattered neutrons. The scattering increases with the elastic stress and decreases with the magnetic field. In particular, in the unloaded state there is a linear relation between the scattered intensity and the plastic shear stress. (author)
International Nuclear Information System (INIS)
Cui, P.X.; Lian, F.L.; Wang, Y.; Wen, Yi; Chu, W.S.; Zhao, H.F.; Zhang, S.; Li, J.; Lin, D.H.; Wu, Z.Y.
2014-01-01
Prion-related protein (PrP), a cell-surface copper-binding glycoprotein, is considered to be responsible for a number of transmissible spongiform encephalopathies (TSEs). The structural conversion of PrP from the normal cellular isoform (PrP C ) to the post-translationally modified form (PrP Sc ) is thought to be relevant to Cu 2+ binding to histidine residues. Rabbits are one of the few mammalian species that appear to be resistant to TSEs, because of the structural characteristics of the rabbit prion protein (RaPrP C ) itself. Here we determined the three-dimensional local structure around the C-terminal high-affinity copper-binding sites using X-ray absorption near-edge structure combined with ab initio calculations in the framework of the multiple-scattering (MS) theory. Result shows that two amino acid resides, Gln97 and Met108, and two histidine residues, His95 and His110, are involved in binding this copper(II) ion. It might help us understand the roles of copper in prion conformation conversions, and the molecular mechanisms of prion-involved diseases. - Highlights: ► The first structure of the metal ion binding site in RaPrP fifth copper-binding site. ► Quantitative determination by XANES spectroscopy combined with ab initio calculations. ► Provide a proof of the roles of copper in prion conformation conversions. ► Provide a proof of the molecular mechanisms of prion-involved diseases
Wang, Shaofeng; Ma, Xu; Zhang, Guoqing; Jia, Yongfeng; Hatada, Keisuke
2016-11-15
Hydrous ferric arsenate (HFA) is an important arsenic-bearing precipitate in the mining-impacted environment and hydrometallurgical tailings. However, there is no agreement on its local atomic structure. The local structure of HFA was reprobed by employing a full-potential multiple scattering (FPMS) analysis, density functional theory (DFT) calculations, and vibrational spectroscopy. The FPMS simulations indicated that the coordination number of the As-Fe, Fe-As, or both in HFA was approximately two. The DFT calculations constructed a structure of HFA with the formula of Fe(HAsO 4 ) x (H 2 AsO 4 ) 1-x (OH) y ·zH 2 O. The presence of protonated arsenate in HFA was also evidenced by vibrational spectroscopy. The As and Fe K-edge X-ray absorption near-edge structure spectra of HFA were accurately reproduced by FPMS simulations using the chain structure, which was also a reasonable model for extended X-Ray absorption fine structure fitting. The FPMS refinements indicated that the interatomic Fe-Fe distance was approximately 5.2 Å, consistent with that obtained by Mikutta et al. (Environ. Sci. Technol. 2013, 47 (7), 3122-3131) using wavelet analysis. All of the results suggested that HFA was more likely to occur as a chain with AsO 4 tetrahedra and FeO 6 octahedra connecting alternately in an isolated bidentate-type fashion. This finding is of significance for understanding the fate of arsenic and the formation of ferric arsenate minerals in an acidic environment.
Directory of Open Access Journals (Sweden)
Saposnik G
2017-01-01
.Results: Out of 161 neurologists who were invited to participate, 96 completed the study (response rate: 60%. Herding was present in 75 (78.1%, having a similar prevalence in MS experts and general neurologists (68.8% vs 82.8%; P=0.12. In multivariate analyses, the number of MS patients seen per week was positively associated with herding (odds ratio [OR] 1.08, 95% CI 1.01–1.14. Conversely, physician’s age, gender, years of practice, setting of practice, or risk preferences were not associated with herding.Conclusion: Herding was a common phenomenon affecting nearly 8 out of 10 neurologists caring for MS patients. Herding may affect medical decisions and lead to poorer outcomes in the management of MS. Keywords: multiple sclerosis, herding, disease-modifying therapy, neuroeconomics, decision-making, risk aversion
Saposnik, Gustavo; Maurino, Jorge; Sempere, Angel P; Ruff, Christian C; Tobler, Philippe N
2017-01-01
Herding is a phenomenon by which individuals follow the behavior of others rather than deciding independently on the basis of their own private information. A herding-like phenomenon can occur in multiple sclerosis (MS) when a neurologist follows a therapeutic recommendation by a colleague even though it is not supported by best practice clinical guidelines. Limited information is currently available on the role of herding in medical care. The objective of this study was to determine the prevalence (and its associated factors) of herding in the management of MS. We conducted a study among neurologists with expertise in MS care throughout Spain. Participants answered questions regarding the management of 20 case scenarios commonly encountered in clinical practice and completed 3 surveys and 4 experimental paradigms based on behavioral economics. The herding experiment consisted of a case scenario of a 40-year-old woman who has been stable for 3 years on subcutaneous interferon and developed a self-limited neurological event. There were no new magnetic resonance imaging (MRI) lesions. Her neurological examination and disability scores were unchanged. She was advised by an MS neurologist to switch from interferon to fingolimod against best practice guidelines. Multivariable logistic regression analysis was conducted to evaluate factors associated with herding. Out of 161 neurologists who were invited to participate, 96 completed the study (response rate: 60%). Herding was present in 75 (78.1%), having a similar prevalence in MS experts and general neurologists (68.8% vs 82.8%; P =0.12). In multivariate analyses, the number of MS patients seen per week was positively associated with herding (odds ratio [OR] 1.08, 95% CI 1.01-1.14). Conversely, physician's age, gender, years of practice, setting of practice, or risk preferences were not associated with herding. Herding was a common phenomenon affecting nearly 8 out of 10 neurologists caring for MS patients. Herding may
Generalized internal multiple imaging
Zuberi, M. A. H.; Alkhalifah, Tariq Ali
2014-01-01
Internal multiples deteriorate the image when the imaging procedure assumes only single scattering, especially if the velocity model does not have sharp contrasts to reproduce such scattering in the Green’s function through forward modeling
Denli, H. H.; Durmus, B.
2016-12-01
The purpose of this study is to examine the factors which may affect the apartment prices with multiple linear regression analysis models and visualize the results by value maps. The study is focused on a county of Istanbul - Turkey. Totally 390 apartments around the county Umraniye are evaluated due to their physical and locational conditions. The identification of factors affecting the price of apartments in the county with a population of approximately 600k is expected to provide a significant contribution to the apartment market.Physical factors are selected as the age, number of rooms, size, floor numbers of the building and the floor that the apartment is positioned in. Positional factors are selected as the distances to the nearest hospital, school, park and police station. Totally ten physical and locational parameters are examined by regression analysis.After the regression analysis has been performed, value maps are composed from the parameters age, price and price per square meters. The most significant of the composed maps is the price per square meters map. Results show that the location of the apartment has the most influence to the square meter price information of the apartment. A different practice is developed from the composed maps by searching the ability of using price per square meters map in urban transformation practices. By marking the buildings older than 15 years in the price per square meters map, a different and new interpretation has been made to determine the buildings, to which should be given priority during an urban transformation in the county.This county is very close to the North Anatolian Fault zone and is under the threat of earthquakes. By marking the apartments older than 15 years on the price per square meters map, both older and expensive square meters apartments list can be gathered. By the help of this list, the priority could be given to the selected higher valued old apartments to support the economy of the country
Scattering of intermediate energy protons
International Nuclear Information System (INIS)
Chaumeaux, Alain.
1980-06-01
The scattering of 1 GeV protons appears to be a powerful means of investigating nuclear matter. We worked with SPESI and the formalism of Kerman-Mc Manus and Thaler. The amplitude of nucleon-nucleon scattering was studied as were the aspects of 1 GeV proton scattering (multiple scattering, absorption, spin-orbit coupling, N-N amplitude, KMT-Glauber comparison, second order effects). The results of proton scattering on 16 O, the isotopes of calcium, 58 Ni, 90 Zr and 208 Pb are given [fr
Lancioni, Giulio E.; O'Reilly, Mark F.; Singh, Nirbhay N.; Sigafoos, Jeff; Buonocunto, Francesca; Sacco, Valentina; Navarro, Jorge; Lanzilotti, Crocifissa; De Tommaso, Marina; Megna, Marisa; Oliva, Doretta
2013-01-01
This study assessed technology-aided programs for helping two post-coma persons, who had emerged from a minimally conscious state and were affected by multiple disabilities, to (a) engage with leisure stimuli and request caregiver's procedures, (b) send out and listen to text messages for communication with distant partners, and (c) combine…
Varghese, Babu; Rajan, Vinayakrishnan; van Leeuwen, Ton G.; Steenbergen, Wiendelt
2007-01-01
In optical Doppler measurements, the path length of the light is unknown. To facilitate quantitative measurements, we develop a phase-modulated Mach-Zehnder interferometer with separate fibers for illumination and detection. With this setup, path-length-resolved dynamic light scattering measurements
Polarized Raman spectroscopy of bone tissue: watch the scattering
Raghavan, Mekhala; Sahar, Nadder D.; Wilson, Robert H.; Mycek, Mary-Ann; Pleshko, Nancy; Kohn, David H.; Morris, Michael D.
2010-02-01
Polarized Raman spectroscopy is widely used in the study of molecular composition and orientation in synthetic and natural polymer systems. Here, we describe the use of Raman spectroscopy to extract quantitative orientation information from bone tissue. Bone tissue poses special challenges to the use of polarized Raman spectroscopy for measurement of orientation distribution functions because the tissue is turbid and birefringent. Multiple scattering in turbid media depolarizes light and is potentially a source of error. Using a Raman microprobe, we show that repeating the measurements with a series of objectives of differing numerical apertures can be used to assess the contributions of sample turbidity and depth of field to the calculated orientation distribution functions. With this test, an optic can be chosen to minimize the systematic errors introduced by multiple scattering events. With adequate knowledge of the optical properties of these bone tissues, we can determine if elastic light scattering affects the polarized Raman measurements.
Light scattering by soap films
Vrij, A.
A theory is constructed describing the scattering from a liquid film (e.g., a soap film) of a light beam polarized normal to the plane of incidence. This scattering is due to the small irregular corrugations caused by thermal motion. The interference of the reflected incident beam with its multiple
Dynamic measurement of forward scattering
DEFF Research Database (Denmark)
Appel-Hansen, Jørgen; Rusch, W.
1975-01-01
A dynamic method for the measurement of forward scattering in a radio anechoic chamber is described. The quantity determined is the induced-field-ratio (IFR) of conducting cylinders. The determination of the IFR is highly sensitive to 1) multiple scattering between the cylinder and the obpring...
International Nuclear Information System (INIS)
Hategan, Cornel; Comisel, Horia; Ionescu, Remus A.
2004-01-01
The quasiresonant scattering consists from a single channel resonance coupled by direct interaction transitions to some competing reaction channels. A description of quasiresonant Scattering, in terms of generalized reduced K-, R- and S- Matrix, is developed in this work. The quasiresonance's decay width is, due to channels coupling, smaller than the width of the ancestral single channel resonance (resonance's direct compression). (author)
Donne, A. J. H.
1994-01-01
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
Katsi, Luckson; Siwadi, Japson; Guzha, Edward; Makoni, Fungai S.; Smits, Stef
Water with all its multiple uses plays a pivotal role in the sustenance of rural livelihoods, especially the poor. As such, the provision of water which go beyond domestic to include water for small-scale productive uses should be encouraged to enhance peoples’ livelihood options by making significant contribution to household income, food security, improved nutrition and health. All these multiple benefits, if combined can assist in the fight against hunger and poverty. This study was conducted in Mashonaland East province, covering Marondera, Murehwa and Uzumba Maramba Pfungwe districts in Zimbabwe for the period December 2005-May 2006 to assess factors which affect multiple uses of water sources at household level. Participatory Rural Appraisal tools such as discussions, observations and interviews were used for data collection. The survey found that people indeed require water for productive purposes apart from domestic uses, which are often given top priority. The study found out that multiple uses of water sources at household level can be affected by segmentation of water services into domestic and productive water supply schemes, technology and system design, water quality and quantity and distance to water sources among other factors. The study recommends that water service providers to be able to provide appropriate, efficient and sustainable services, they should understand and appreciate that people’s water needs are integrated and are part and parcel of their multifaceted livelihood strategies.
Directory of Open Access Journals (Sweden)
Sandra Guerra
2011-11-01
Full Text Available We analyze the simultaneous participation of directors in multiple companies and its effects on boards’ roles and activities. By sitting in multiple boards, directors may face time scarcity and they may be too busy to adequately perform their tasks. Using survey questionnaires about board’s activities, which were directly sent to firms and their directors, this paper founds that busy boards are considered to be less active, less independent and less relevant to firms. Additionally, these boards are less committed to their responsibilities, such as hiring/firing the CEO and evaluating executives’ performance. They also do not monitor the firm’s risk properly. Our results present an insider perception of the board’s roles and activities, which can be useful for market regulators and policy-makers.
Ondeck, Nathaniel T; Fu, Michael C; Skrip, Laura A; McLynn, Ryan P; Su, Edwin P; Grauer, Jonathan N
2018-03-01
Despite the advantages of large, national datasets, one continuing concern is missing data values. Complete case analysis, where only cases with complete data are analyzed, is commonly used rather than more statistically rigorous approaches such as multiple imputation. This study characterizes the potential selection bias introduced using complete case analysis and compares the results of common regressions using both techniques following unicompartmental knee arthroplasty. Patients undergoing unicompartmental knee arthroplasty were extracted from the 2005 to 2015 National Surgical Quality Improvement Program. As examples, the demographics of patients with and without missing preoperative albumin and hematocrit values were compared. Missing data were then treated with both complete case analysis and multiple imputation (an approach that reproduces the variation and associations that would have been present in a full dataset) and the conclusions of common regressions for adverse outcomes were compared. A total of 6117 patients were included, of which 56.7% were missing at least one value. Younger, female, and healthier patients were more likely to have missing preoperative albumin and hematocrit values. The use of complete case analysis removed 3467 patients from the study in comparison with multiple imputation which included all 6117 patients. The 2 methods of handling missing values led to differing associations of low preoperative laboratory values with commonly studied adverse outcomes. The use of complete case analysis can introduce selection bias and may lead to different conclusions in comparison with the statistically rigorous multiple imputation approach. Joint surgeons should consider the methods of handling missing values when interpreting arthroplasty research. Copyright © 2017 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Sitenko, A.
1991-01-01
This book emerged out of graduate lectures given by the author at the University of Kiev and is intended as a graduate text. The fundamentals of non-relativistic quantum scattering theory are covered, including some topics, such as the phase-function formalism, separable potentials, and inverse scattering, which are not always coverded in textbooks on scattering theory. Criticisms of the text are minor, but the reviewer feels an inadequate index is provided and the citing of references in the Russian language is a hindrance in a graduate text
Intermediate energy nucleon-deuteron scattering theory.
Wilson, J. W.
1973-01-01
Sloan's conclusion (1969) that terms of the multiple-scattering series beyond single scattering contribute only to S- and P-wave amplitudes in an S-wave separable model is examined. A comparison of experiments with the calculation at 146 MeV shows that the conclusion is valid in nucleon-deuteron scattering applications.
International Nuclear Information System (INIS)
Stirling, W.G.; Perry, S.C.
1996-01-01
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 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
Treacy, C.
2015-01-01
Sex is an important part of life for many people, therefore dealing with erectile problems, living with the effects of physical injury, changes in your appearance or side-effects of treatment can have an enormous impact on your sex life and relationships. Normal sexual behaviour and erectile function depends on a complex interaction between various body-systems, including the brain, nerves, blood-supply and hormones. All of these systems (alone or in combination) may be affected following mul...
Scattering by two spheres: Theory and experiment
DEFF Research Database (Denmark)
Bjørnø, Irina; Jensen, Leif Bjørnø
1998-01-01
of suspended sediments. The scattering properties of single regular-shaped particles have been studied in depth by several authors in the past. However, single particle scattering cannot explain all features of scattering by suspended sediment. When the concentration of particles exceeds a certain limit...... on three issues: (1) to develop a simplified theory for scattering by two elastical spheres; (2) to measure the scattering by two spheres in a water tank, and (3) to compare the theoretical/numerical results with the measured data. A number of factors influencing multiple scattering, including...
Wang, Lei; Baskin, Jerry M; Baskin, Carol C; Cornelissen, J Hans C; Dong, Ming; Huang, Zhenying
2012-09-25
Maternal effects may influence a range of seed traits simultaneously and are likely to be context-dependent. Disentangling the interactions of plant phenotype and growth environment on various seed traits is important for understanding regeneration and establishment of species in natural environments. Here, we used the seed-dimorphic plant Suaeda aralocaspica to test the hypothesis that seed traits are regulated by multiple maternal effects. Plants grown from brown seeds had a higher brown:black seed ratio than plants from black seeds, and germination percentage of brown seeds was higher than that of black seeds under all conditions tested. However, the coefficient of variation (CV) for size of black seeds was higher than that of brown seeds. Seeds had the smallest CV at low nutrient and high salinity for plants from brown seeds and at low nutrient and low salinity for plants from black seeds. Low levels of nutrients increased size and germinability of black seeds but did not change the seed morph ratio or size and germinability of brown seeds. High levels of salinity decreased seed size but did not change the seed morph ratio. Seeds from high-salinity maternal plants had a higher germination percentage regardless of level of germination salinity. Our study supports the multiple maternal effects hypothesis. Seed dimorphism, nutrient and salinity interacted in determining a range of seed traits of S. aralocaspica via bet-hedging and anticipatory maternal effects. This study highlights the importance of examining different maternal factors and various offspring traits in studies that estimate maternal effects on regeneration.
Sushida, Hirotoshi; Ishibashi, Naoki; Zendo, Takeshi; Wilaipun, Pongtep; Leelawatcharamas, Vichien; Nakayama, Jiro; Sonomoto, Kenji
2018-02-13
EnkT is a novel ATP-binding cassette (ABC) transporter responsible for secretion of four bacteriocins, enterocins NKR-5-3A, C, D, and Z (Ent53A, C, D, and Z), produced by Enterococcus faecium NKR-5-3. It is generally recognized that the secretion of a bacteriocin requires a dedicated ABC transporter, although molecular mechanisms of this secretion are yet to be revealed. In order to characterize the unique ability of EnkT to secrete multiple bacteriocins, the role of N-terminal leader peptides of bacteriocin precursors was evaluated using Ent53C precursor as a model. The 18-amino acid leader peptide of Ent53C (Lc) was modified by site-directed mutagenesis to generate various point mutations, truncations, or extensions, and substitutions with other leader peptides. The impact of these Lc mutations on Ent53C secretion was evaluated using a quantitative antimicrobial activity assay. We observed that Ent53C production increased with Ala substitution of the highly conserved C-terminal double glycine residues that are recognized as the cleavage site. In contrast, Ent53C antimicrobial activity decreased, with decrease in the length of the putative α-helix-forming region of Lc. Furthermore, EnkT recognized and transported Ent53C of the transformants possessing heterologous leader peptides of enterocin A, pediocin PA-1, brochocins A and B, and lactococcins Qα and Qβ. These results indicated that EnkT shows significant tolerance towards the sequence and length of leader peptides, to secrete multiple bacteriocins. This further demonstrates the functional diversity of bacteriocin ABC transporters and the importance of leader peptides as their recognition motif. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
de Jong, Simone; Chepelev, Iouri; Janson, Esther; Strengman, Eric; van den Berg, Leonard H; Veldink, Jan H; Ophoff, Roel A
2012-09-06
Chromosome 17q21.31 contains a common inversion polymorphism of approximately 900 kb in populations with European ancestry. Two divergent MAPT haplotypes, H1 and H2 are described with distinct linkage disequilibrium patterns across the region reflecting the inversion status at this locus. The MAPT H1 haplotype has been associated with progressive supranuclear palsy, corticobasal degeneration, Parkinson's disease and Alzheimer's disease, while the H2 is linked to recurrent deletion events associated with the 17q21.31 microdeletion syndrome, a disease characterized by developmental delay and learning disability. In this study, we investigate the effect of the inversion on the expression of genes in the 17q21.31 region. We find the expression of several genes in and at the borders of the inversion to be affected; specific either to whole blood or different regions of the human brain. The H1 haplotype was found to be associated with an increased expression of LRRC37A4, PLEKH1M and MAPT. In contrast, a decreased expression of MGC57346, LRRC37A and CRHR1 was associated with H1. Studies thus far have focused on the expression of MAPT in the inversion region. However, our results show that the inversion status affects expression of other genes in the 17q21.31 region as well. Given the link between the inversion status and different neurological diseases, these genes may also be involved in disease pathology, possibly in a tissue-specific manner.
Directory of Open Access Journals (Sweden)
Yi-Jin Chen
Full Text Available Pancreatic cancer is one of the most lethal types of cancer with a 5-year survival rate of ~5%. Histone deacetylases (HDACs participate in many cellular processes, including carcinogenesis, and pharmacological inhibition of HDACs has emerged as a potential therapeutic strategy. In this study, we explored antitumor activity of the novel HDAC inhibitor AR-42 in pancreatic cancer.Human pancreatic cancer cell lines BxPC-3 and PANC-1 were used in this study. Real-time PCR, RT-PCR, and western blotting were employed to investigate expression of specific genes and proteins, respectively. Translocation of apoptosis-inducing factor was investigated by immunofluorescence and subcellular fractionation. The number of apoptotic cells, cell cycle stages, and reactive oxygen species (ROS generation levels were determined by flow cytometry. Cell invasiveness was examined by the Matrigel invasion assay. Efficacy of AR-42 in vivo was evaluated by utilizing BxPC-3 xenograft mouse model.AR-42 inhibited pancreatic cancer cell proliferation by causing G2/M cell cycle arrest via regulating expression levels of genes and proteins involved in cell cycle. AR-42 also induced ROS generation and DNA damage, triggering apoptosis of pancreatic cancer cells via both caspase-3-dependent and caspase-3-independent pathways. In addition, AR-42 increased expression levels of negative regulators of p53 (miR-125b, miR-30d, and miR33, which could contribute to lower expression level of mutant p53 in pancreatic cancer cells. Cell invasion assay showed that AR-42 reduced cancer cell aggressiveness and significantly diminished BxPC-3 xenograft tumor growth in vivo.AR-42, a novel HDAC inhibitor, inhibited pancreatic cancer cells by regulating p53 expression, inducing cell cycle arrest, particularly at the G2/M stage, and activating multiple apoptosis pathways. Additionally, AR-42 inhibited cell invasiveness and potently suppressed pancreatic cancer tumors in vivo. We conclude that by
International Nuclear Information System (INIS)
Ferro Orozco, A.M.; Contreras, E.M.; Zaritzky, N.E.
2010-01-01
The objectives of the present work were: (i) to analyze the capacity of activated sludge to reduce hexavalent chromium using different carbon sources as electron donors in batch reactors, (ii) to determine the relationship between biomass growth and the amount of Cr(VI) reduced considering the effect of the nitrogen to carbon source ratio, and (iii) to determine the effect of the Cr(VI) acclimation stage on the performance of the biological chromium reduction assessing the stability of the Cr(VI) reduction capacity of the activated sludge. The highest specific Cr(VI) removal rate (q Cr ) was attained with cheese whey or lactose as electron donors decreasing in the following order: cheese whey ∼ lactose > glucose > citrate > acetate. Batch assays with different nitrogen to carbon source ratio demonstrated that biological Cr(VI) reduction is associated to the cell multiplication phase; as a result, maximum Cr(VI) removal rates occur when there is no substrate limitation. The biomass can be acclimated to the presence of Cr(VI) and generate new cells that maintain the ability to reduce chromate. Therefore, the activated sludge process could be applied to a continuous Cr(VI) removal process.
The Scattering Outcomes of Kepler Circumbinary Planets: Planet Mass Ratio
Energy Technology Data Exchange (ETDEWEB)
Gong, Yan-Xiang; Ji, Jianghui, E-mail: yxgong@pmo.ac.cn, E-mail: jijh@pmo.ac.cn [CAS Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)
2017-11-01
Recent studies reveal that the free eccentricities of Kepler-34b and Kepler-413b are much larger than their forced eccentricities, implying that scattering events may take place in their formation. The observed orbital configuration of Kepler-34b cannot be well reproduced in disk-driven migration models, whereas a two-planet scattering scenario can play a significant role of shaping the planetary configuration. These studies indicate that circumbinary planets discovered by Kepler may have experienced scattering process. In this work, we extensively investigate the scattering outcomes of circumbinary planets focusing on the effects of planet mass ratio . We find that the planetary mass ratio and the the initial relative locations of planets act as two important parameters that affect the eccentricity distribution of the surviving planets. As an application of our model, we discuss the observed orbital configurations of Kepler-34b and Kepler-413b. We first adopt the results from the disk-driven models as the initial conditions, then simulate the scattering process that occurs in the late evolution stage of circumbinary planets. We show that the present orbital configurations of Kepler-34b and Kepler-413b can be well reproduced when considering a two unequal-mass planet ejection model. Our work further suggests that some of the currently discovered circumbinary single-planet systems may be survivors of original multiple-planet systems. The disk-driven migration and scattering events occurring in the late stage both play an irreplaceable role in sculpting the final systems.
International Nuclear Information System (INIS)
Botto, D.J.; Pratt, R.H.
1979-05-01
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 -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
Energy Technology Data Exchange (ETDEWEB)
Botto, D.J.; Pratt, R.H.
1979-05-01
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.
International Nuclear Information System (INIS)
Michalon-Mentzer, Marie-Eve.
1979-01-01
From a study of the charged multiplicity distributions, antipd and antipn interactions in the range of incident momentum going from 3 to 15 GeV/c have been analysed. The antipd and antipn topological cross sections have been calculated. The behavior of the different statistical moments obtained from the charged multiplicities as function of the incident momentum have been studied. We have analysed rescattering phenomena inside the deuteron and the rescattering fraction per antipd collisions was found to be of the order of 20%. Data are in good agreement with the predictions of the energy flux cascade model and the coherent tube model. General features of the antipn annihilation processes have been also studied in particular by means of collective variables like sphericity and thrust which describe jets properties or alignment effects of interactions [fr
van den Akker, Lizanne E; Beckerman, Heleen; Collette, Emma H; Twisk, Jos Wr; Bleijenberg, Gijs; Dekker, Joost; Knoop, Hans; de Groot, Vincent
2017-10-01
Fatigue is a common symptom in multiple sclerosis (MS) and often restricts societal participation. Cognitive behavioral therapy (CBT) may alleviate MS-related fatigue, but evidence in literature is inconclusive. To evaluate the effectiveness of CBT to improve MS-related fatigue and participation. In a multi-center, assessor-masked, randomized controlled trial, participants with severe MS-related fatigue were assigned to CBT or control treatment. CBT consisted of 12 individual sessions with a psychologist trained in CBT, the control treatment consisted of three consultations with a MS nurse, both delivered over 16 weeks. Assessments were at baseline, 8, 16 (i.e. post-intervention), 26, and 52 weeks post-baseline. Primary outcomes were the Checklist Individual Strength-fatigue subscale (CIS20r fatigue) and the Impact on Participation and Autonomy questionnaire (IPA). Data were analyzed according to the intention-to-treat principle, using mixed-model analysis. Between 2011 and 2014, 91 patients were randomized (CBT: n = 44; control: n = 47). Between-group analysis showed a positive post-intervention effect for CBT on CIS20r fatigue (T16: -6.7 (95% confidence interval (CI) = -10.7; -2.7) points) that diminished during follow-up (T52: 0.5 (95% CI = -3.6; 4.4)). No clinically relevant effects were found on societal participation. Severe MS-related fatigue can be reduced effectively with CBT in the short term. More research is needed on how to maintain this effect over the long term.
Energy Technology Data Exchange (ETDEWEB)
Reinhold, C.O. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6373 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996-1200 (United States); Arbo, D.G. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6373 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996-1200 (United States); Instituto de Astronomia y Fisica del Espacio, C.C. 67, Suc. 28, 1428 Buenos Aires (Argentina); Burgdoerfer, J. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6373 (United States); Institute for Theoretical Physics, Vienna University of Technology, A-1040 Vienna (Austria); Gervais, B. [Centre Interdisciplinaire de Recherche Ions Lasers, Laboratoire Mixte, CEA-CNRS-ISMRA, BP 5133, 14070 Caen Cedex 05 (France); Lamour, E. [Centre Interdisciplinaire de Recherche Ions Lasers, Laboratoire Mixte, CEA-CNRS-ISMRA, BP 5133, 14070 Caen Cedex 05 (France); Groupe de Physique des Solides, CNRS UMR 75-88, Universites Paris 6 et Paris 7, 75251 Paris Cedex 05 (France); Vernhet, D.; Rozet, J.P. [Groupe de Physique des Solides, CNRS UMR 75-88, Universites Paris 6 et Paris 7, 75251 Paris Cedex 05 (France)
2000-02-28
We present a study of the sub-shell populations of 13.6 MeV/u Ar{sup 17+} ions after transmission through thin carbon foils. We show that the combined effect of the wake field induced by the ion in the solid and multiple collisions leads to a strongly enhanced population of high angular momentum states. These results explain new experimental data for absolute total line emission intensities. (author). Letter-to-the-editor.
Directory of Open Access Journals (Sweden)
Francesco Nazzi
2018-03-01
Full Text Available Any attempt to outline a logical framework in which to interpret the honey bee health decline and its contribution to elevated colony losses should recognize the importance of the multifactorial nature of the responsible syndrome and provide a functional model as a basis for defining and testing working hypotheses. We propose that covert infections by deformed wing virus (DWV represent a sword of Damocles permanently threatening the survival of honey bee colonies and suggest that any factor affecting the honey bee’s antiviral defenses can turn this pathogen into a killer. Here we discuss the available experimental evidence in the framework of a model based on honey bee immune competence as affected by multiple stress factors that is proposed as a conceptual tool for analyzing bee mortality and its underlying mechanisms.
Chakraborty, Satabdi; Bhatia, Triptish; Anderson, Carol; Nimgaonkar, Vishwajit L; Deshpande, Smita N
2013-01-01
There is considerable evidence that family psycho-education combined with pharmacological intervention for patients with schizophrenia increases family understanding of the illness, reduces the familial burden of care, and improves patient outcomes. However, no studies have determined whether the burden of care is greater for those families with more than one ill member (multiplex) than for families with a single-affected individual (simplex), and whether psycho-educational programs should be adapted to meet the specific needs of multiplex families. This study was conducted at a tertiary care postgraduate teaching hospital in New Delhi, India. Caregivers in simplex [n = 50] and multiplex families [n = 30] were compared with regard to levels of burden, coping, and the impact of psycho-education on family functioning. All the caregiver participants attended eight bimonthly, psycho-educational intervention sessions. They were assessed on the Burden Assessment Schedule (BAS) and the Coping Check List (CCL) before and after psycho-education. Caregivers from the multiplex families reported significantly more burden on two domains of the BAS, but there were no significant differences between the groups with regard to coping on the CCL. Following psycho-education, significant improvement occurred in the majority of domains of the BAS and the CCL; the effect sizes varied by domain and family type. Multiplex families face a greater burden of care compared with simplex families. Currently, available psycho-education programs are moderately effective for such families.
Generalized internal multiple imaging
Zuberi, M. A. H.
2014-08-05
Internal multiples deteriorate the image when the imaging procedure assumes only single scattering, especially if the velocity model does not have sharp contrasts to reproduce such scattering in the Green’s function through forward modeling. If properly imaged, internal multiples (internally scattered energy) can enhance the seismic image. Conventionally, to image internal multiples, accurate, sharp contrasts in the velocity model are required to construct a Green’s function with all the scattered energy. As an alternative, we have developed a generalized internal multiple imaging procedure that images any order internal scattering using the background Green’s function (from the surface to each image point), constructed from a smooth velocity model, usually used for conventional imaging. For the first-order internal multiples, the approach consisted of three steps, in which we first back propagated the recorded surface seismic data using the background Green’s function, then crosscorrelated the back-propagated data with the recorded data, and finally crosscorrelated the result with the original background Green’s function. This procedure images the contribution of the recorded first-order internal multiples, and it is almost free of the single-scattering recorded energy. The cost includes one additional crosscorrelation over the conventional single-scattering imaging application. We generalized this method to image internal multiples of any order separately. The resulting images can be added to the conventional single-scattering image, obtained, e.g., from Kirchhoff or reverse-time migration, to enhance the image. Application to synthetic data with reflectors illuminated by multiple scattering (double scattering) demonstrated the effectiveness of the approach.
Liu, Dajun; Shang, Huiping; Liu, Ying
2016-07-12
Stanniocalcin-1 (STC-1) protects against renal ischemia-reperfusion injury (RIRI). However, the molecular mechanisms remain widely unknown. STC-1 inhibits reactive oxygen species (ROS), whereas most ROS-mediated pathways are associated with ischemic injury. Therefore, to explore the mechanism, the effects of STC-1 on ROS-medicated pathways were studied. Non-traumatic vascular clamps were used to establish RIRI mouse models. The serum levels of STC-1, interleukin-6 (IL-6), interferon (IFN) γ, P53, and capase-3 were measured by ELISA kits. Superoxide dismutase (SOD) and malondialdehyde (MDA) were measured by fluorescence spectrofluorometer. All these molecules changed significantly in a RIRI model mouse when compared with those in a sham control. Kidney cells were isolated from sham and model mice. STC-1 was overexpressed or knockout in these kidney cells. The molecules in ROS-medicated pathways were measured by real-time quantitative PCR and Western blot. The results showed that STC-1 is an effective ROS scavenger. The serum levels of STC-1, MDA and SOD activity were increased while the serum levels of IL-6, iIFN-γ, P53, and capase-3 were decreased in a model group when compared with a sham control (p ROS-mediated molecules. Therefore, STC-1 maybe improve anti-inflammation, anti-oxidant and anti-apoptosis activities by affecting ROS-mediated pathways, especially the phospho-modifications of the respective proteins, resulting in the increase of SOD and reduce of capase-3, p53, IL-6 and IFN-γ.
Energy Technology Data Exchange (ETDEWEB)
Baltzer, Pascal A.T., E-mail: patbaltzer@gmail.com [Department of Biomedical Imaging and Imge-guided Therapy, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna (Austria); Kaiser, Werner Alois [Department of Diagnostic and Interventional Radiology, University Hospital Jena, Erlanger Allee 101, 07740 Jena (Germany); Dietzel, Matthias, E-mail: dietzelmatthias2@hotmail.com [Department of Neuroradiology, University Hospital Erlangen, Schwabachanlage 6, 91054 Erlangen (Germany)
2015-01-15
reader experience (P = 0.005) on diagnostic performance. Conclusions: Non-mass lesion type and low reader experience negatively affect the diagnostic performance of breast MRI in a non-screening setting.
Ram, Nilam; Conroy, David E; Pincus, Aaron L; Lorek, Amy; Rebar, Amanda; Roche, Michael J; Coccia, Michael; Morack, Jennifer; Feldman, Josh; Gerstorf, Denis
Human development is characterized by the complex interplay of processes that manifest at multiple levels of analysis and time-scales. We introduce the Intraindividual Study of Affect, Health and Interpersonal Behavior (iSAHIB) as a model for how multiple time-scale study designs facilitate more precise articulation of developmental theory. Combining age heterogeneity, longitudinal panel, daily diary, and experience sampling protocols, the study made use of smartphone and web-based technologies to obtain intensive longitudinal data from 150 persons age 18-89 years as they completed three 21-day measurement bursts ( t = 426 bursts, t = 8,557 days) wherein they provided reports on their social interactions ( t = 64,112) as they went about their daily lives. We illustrate how multiple time-scales of data can be used to articulate bioecological models of development and the interplay among more 'distal' processes that manifest at 'slower' time-scales (e.g., age-related differences and burst-to-burst changes in mental health) and more 'proximal' processes that manifest at 'faster' time-scales (e.g., changes in context that progress in accordance with the weekly calendar and family influence processes).
Vector boson scattering at CLIC
Energy Technology Data Exchange (ETDEWEB)
Kilian, Wolfgang; Fleper, Christian [Department Physik, Universitaet Siegen, 57068 Siegen (Germany); Reuter, Juergen [DESY Theory Group, 22603 Hamburg (Germany); Sekulla, Marco [Institut fuer Theoretische Physik, Karlsruher Institut fuer Technologie, 76131 Karlsruhe (Germany)
2016-07-01
Linear colliders operating in a range of multiple TeV are able to investigate the details of vector boson scattering and electroweak symmetry breaking. We calculate cross sections with the Monte Carlo generator WHIZARD for vector boson scattering processes at the future linear e{sup +} e{sup -} collider CLIC. By finding suitable cuts, the vector boson scattering signal processes are isolated from the background. Finally, we are able to determine exclusion sensitivities on the non-Standard Model parameters of the relevant dimension eight operators.
Directory of Open Access Journals (Sweden)
Aimin Zhou
2018-05-01
Full Text Available Plant SWEETs (Sugars Will Eventually be Exported Transporters affect the growth of plants by regulating the transport of sugar from source to sink and its intracellular transport between different organelles. In this study, DsSWEET17 from Dianthus spiculifolius was identified and characterized. Real-time quantitative PCR analysis revealed that the expression of DsSWEET17 was affected by exogenous application of fructose and glucose as well as under salt, osmotic, and oxidation stress. Colocalization experiments showed that the DsSWEET17-GFP (green fluorescent protein fusion protein was localized to the FM4-64-labeled tonoplasts in Arabidopsis. Compared to the wild type, the transgenic Arabidopsis seedlings overexpressing DsSWEET17 had longer roots, greater fresh weight, and a faster root growth upon exogenous application of fructose. Furthermore, transgenic Arabidopsis seedlings had significantly higher fructose accumulation than was observed for the wild-type seedlings. The analysis of root length revealed that transgenic Arabidopsis had higher tolerance to salt, osmotic, and oxidative stresses. Taken together, our results suggest that DsSWEET17 may be a tonoplast sugar transporter, and its overexpression affects sugar metabolism and confers multiple stress tolerance in Arabidopsis.
Zhou, Aimin; Ma, Hongping; Feng, Shuang; Gong, Shufang; Wang, Jingang
2018-05-24
Plant SWEETs (Sugars Will Eventually be Exported Transporters) affect the growth of plants by regulating the transport of sugar from source to sink and its intracellular transport between different organelles. In this study, DsSWEET17 from Dianthus spiculifolius was identified and characterized. Real-time quantitative PCR analysis revealed that the expression of DsSWEET17 was affected by exogenous application of fructose and glucose as well as under salt, osmotic, and oxidation stress. Colocalization experiments showed that the DsSWEET17-GFP (green fluorescent protein) fusion protein was localized to the FM4-64-labeled tonoplasts in Arabidopsis . Compared to the wild type, the transgenic Arabidopsis seedlings overexpressing DsSWEET17 had longer roots, greater fresh weight, and a faster root growth upon exogenous application of fructose. Furthermore, transgenic Arabidopsis seedlings had significantly higher fructose accumulation than was observed for the wild-type seedlings. The analysis of root length revealed that transgenic Arabidopsis had higher tolerance to salt, osmotic, and oxidative stresses. Taken together, our results suggest that DsSWEET17 may be a tonoplast sugar transporter, and its overexpression affects sugar metabolism and confers multiple stress tolerance in Arabidopsis .
International Nuclear Information System (INIS)
Leader, Elliot
1991-01-01
With very few unexplained results to challenge conventional ideas, physicists have to look hard to search for gaps in understanding. An area of physics which offers a lot more than meets the eye is elastic and diffractive scattering where particles either 'bounce' off each other, emerging unscathed, or just graze past, emerging relatively unscathed. The 'Blois' workshops provide a regular focus for this unspectacular, but compelling physics, attracting highly motivated devotees
International Nuclear Information System (INIS)
1991-02-01
The annual report on hand gives an overview of the research work carried out in the Laboratory for Neutron Scattering (LNS) of the ETH Zuerich in 1990. Using the method of neutron scattering, it is possible to examine in detail the static and dynamic properties of the condensed material. In accordance with the multidisciplined character of the method, the LNS has for years maintained a system of intensive co-operation with numerous institutes in the areas of biology, chemistry, solid-state physics, crystallography and materials research. In 1990 over 100 scientists from more than 40 research groups both at home and abroad took part in the experiments. It was again a pleasure to see the number of graduate students present, who were studying for a doctorate and who could be introduced into the neutron scattering during their stay at the LNS and thus were in the position to touch on central ways of looking at a problem in their dissertation using this modern experimental method of solid-state research. In addition to the numerous and interesting ways of formulating the questions to explain the structure, nowadays the scientific programme increasingly includes particularly topical studies in connection with high temperature-supraconductors and materials research
Friedrich, Harald
2016-01-01
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...
[Inelastic electron scattering from surfaces
International Nuclear Information System (INIS)
1993-01-01
This program uses ab-initio and multiple scattering to study surface dynamical processes; high-resolution electron-energy loss spectroscopy is used in particular. Off-specular excitation cross sections are much larger if electron energies are in the LEED range (50--300 eV). The analyses have been extended to surfaces of ordered alloys. Phonon eigenvectors and eigenfrequencies were used as inputs to electron-energy-loss multiple scattering cross section calculations. Work on low-energy electron and positron holography is mentioned
Determination of Atmospheric Aerosol Characteristics from the Polarization of Scattered Radiation
Harris, F. S., Jr.; McCormick, M. P.
1973-01-01
Aerosols affect the polarization of radiation in scattering, hence measured polarization can be used to infer the nature of the particles. Size distribution, particle shape, real and absorption parts of the complex refractive index affect the scattering. From Lorenz-Mie calculations of the 4-Stokes parameters as a function of scattering angle for various wavelengths the following polarization parameters were plotted: total intensity, intensity of polarization in plane of observation, intensity perpendicular to the plane of observation, polarization ratio, polarization (using all 4-Stokes parameters), plane of the polarization ellipse and its ellipticity. A six-component log-Gaussian size distribution model was used to study the effects of the nature of the polarization due to variations in the size distribution and complex refractive index. Though a rigorous inversion from measurements of scattering to detailed specification of aerosol characteristics is not possible, considerable information about the nature of the aerosols can be obtained. Only single scattering from aerosols was used in this paper. Also, the background due to Rayleigh gas scattering, the reduction of effects as a result of multiple scattering and polarization effects of possible ground background (airborne platforms) were not included.
Bursting behaviours in cascaded stimulated Brillouin scattering
International Nuclear Information System (INIS)
Liu Zhan-Jun; He Xian-Tu; Zheng Chun-Yang; Wang Yu-Gang
2012-01-01
Stimulated Brillouin scattering is studied by numerically solving the Vlasov—Maxwell system. A cascade of stimulated Brillouin scattering can occur when a linearly polarized laser pulse propagates in a plasma. It is found that a stimulated Brillouin scattering cascade can reduce the scattering and increase the transmission of light, as well as introduce a bursting behaviour in the evolution of the laser-plasma interaction. The bursting time in the reflectivity is found to be less than half the ion acoustic period. The ion temperature can affect the stimulated Brillouin scattering cascade, which can repeat several times at low ion temperatures and can be completely eliminated at high ion temperatures. For stimulated Brillouin scattering saturation, higher-harmonic generation and wave—wave interaction of the excited ion acoustic waves can restrict the amplitude of the latter. In addition, stimulated Brillouin scattering cascade can restrict the amplitude of the scattered light. (physics of gases, plasmas, and electric discharges)
Multiple sclerosis (MS) is a nervous system disease that affects your brain and spinal cord. It damages the myelin sheath, the material that surrounds and protects your nerve cells. This damage slows down ...
Rainone, Nunzia; Chiodi, Alessandro; Lanzillo, Roberta; Magri, Valeria; Napolitano, Anna; Morra, Vincenzo Brescia; Valerio, Paolo; Freda, Maria Francesca
2017-03-01
To investigate the moderating role of resilience in the relationship between affective disorders and Health-Related Quality of Life (HRQoL) for adolescents and young adults with multiple sclerosis (MS). A quantitative methodology was adopted. Fifty-three adolescents and young adults were interviewed to assess resilience as a personality trait (Ego-Resiliency Scale) and resilience as an interactive competence (CYRM-28), Health-Related Quality of Life (PedsQL 4.0), depression and anxiety (BDI-II and STAI-Y). Affective disorders, both depression (β = -.38, p moderating role of resilience competence using individual resources on the relationship between the Depression Cognitive Factor and Emotional Functioning. Data show that in step 2 of the regression analysis, we obtained a variation of β = -.45 (p moderating effect of resilience was significant regarding the increase in R 2 (p moderates the relationship between the Depression Cognitive Factor and Emotional Functioning in adolescents with MS. Our study suggests that to improve well-being for adolescents with MS resilience could play a key role.
Energy Technology Data Exchange (ETDEWEB)
Sun, Hongwei; Pistorius, Stephen [Department of Physics and Astronomy, University of Manitoba, CancerCare, Manitoba (Canada)
2016-08-15
PET images are affected by the presence of scattered photons. Incorrect scatter-correction may cause artifacts, particularly in 3D PET systems. Current scatter reconstruction methods do not distinguish between single and higher order scattered photons. A dual-scattered reconstruction method (GDS-MLEM) that is independent of the number of Compton scattering interactions and less sensitive to the need for high energy resolution detectors, is proposed. To avoid overcorrecting for scattered coincidences, the attenuation coefficient was calculated by integrating the differential Klein-Nishina cross-section over a restricted energy range, accounting only for scattered photons that were not detected. The optimum image can be selected by choosing an energy threshold which is the upper energy limit for the calculation of the cross-section and the lower limit for scattered photons in the reconstruction. Data was simulated using the GATE platform. 500,000 multiple scattered photon coincidences with perfect energy resolution were reconstructed using various methods. The GDS-MLEM algorithm had the highest confidence (98%) in locating the annihilation position and was capable of reconstructing the two largest hot regions. 100,000 photon coincidences, with a scatter fraction of 40%, were used to test the energy resolution dependence of different algorithms. With a 350–650 keV energy window and the restricted attenuation correction model, the GDS-MLEM algorithm was able to improve contrast recovery and reduce the noise by 7.56%–13.24% and 12.4%–24.03%, respectively. This approach is less sensitive to the energy resolution and shows promise if detector energy resolutions of 12% can be achieved.
Directory of Open Access Journals (Sweden)
Sara Carletto
2017-11-01
Full Text Available Purpose: Mindfulness interventions have been shown to treat depressive symptoms and improve quality of life in patients with several chronic diseases, including multiple sclerosis, but to date most evaluation of the effectiveness of mindfulness interventions in multiple sclerosis have used patients receiving standard care as the control group. Hence we decided to evaluate the effectiveness of a group-based body-affective mindfulness intervention by comparing it with a psycho-educational intervention, by means of a randomized controlled clinical trial. The outcome variables (i.e., depression, anxiety, perceived stress, illness perception, fatigue and quality of life were evaluated at the end of the interventions (T1 and after a further 6 months (T2.Methods: Of 90 multiple sclerosis patients with depressive symptoms (Beck Depression Inventory-II score greater than 13 who were randomized, 71 completed the intervention (mindfulness group n = 36; psycho-educational group n = 35. The data were analyzed with GLM repeated-measures ANOVA followed by pairwise comparisons.Results: Per-protocol analysis revealed a time by group interaction on Beck Depression Inventory-II score, with the mindfulness intervention producing a greater reduction in score than the psycho-educational intervention, both at T1 and at T2. Furthermore, the mindfulness intervention improved patients’ quality of life and illness perception at T1 relative to the baseline and these improvements were maintained at the follow-up assessment (T2. Lastly, both interventions were similarly effective in reducing anxiety and perceived stress; these reductions were maintained at T2. A whole-sample intention-to-treat (ITT analysis broadly confirmed the effectiveness of the mindfulness intervention.Conclusion: In conclusion, these results provide methodologically robust evidence that in multiple sclerosis patients with depressive symptoms mindfulness interventions improve symptoms of depression
Pion deuteron scattering at intermediate energies
International Nuclear Information System (INIS)
Ferreira, E.M.
1978-09-01
A comparison is made of results of calculations of πd elastic scattering cross section using multiple scattering and three-body equations, in relation to their ability to reproduce the experimental data at intermediate energies. It is shown that the two methods of theoretical calculation give quite similar curves for the elastic differential cross sections, and that both fail in reproducing backward scattering data above 200MeV. The new accurate experimental data on πd total cross section as a function of the energy are confronted with the theoretical values obtained from the multiple scattering calculation through the optical theorem. Comparison is made between the values of the real part of the forward amplitude evaluated using dispersion relations and using the multiple scattering method [pt
PLANET-PLANET SCATTERING LEADS TO TIGHTLY PACKED PLANETARY SYSTEMS
International Nuclear Information System (INIS)
Raymond, Sean N.; Barnes, Rory; Veras, Dimitri; Armitage, Philip J.; Gorelick, Noel; Greenberg, Richard
2009-01-01
The known extrasolar multiple-planet systems share a surprising dynamical attribute: they cluster just beyond the Hill stability boundary. Here we show that the planet-planet scattering model, which naturally explains the observed exoplanet eccentricity distribution, can reproduce the observed distribution of dynamical configurations. We calculated how each of our scattered systems would appear over an appropriate range of viewing geometries; as Hill stability is weakly dependent on the masses, the mass-inclination degeneracy does not significantly affect our results. We consider a wide range of initial planetary mass distributions and find that some are poor fits to the observed systems. In fact, many of our scattering experiments overproduce systems very close to the stability boundary. The distribution of dynamical configurations of two-planet systems may provide better discrimination between scattering models than the distribution of eccentricity. Our results imply that, at least in their inner regions which are weakly affected by gas or planetesimal disks, planetary systems should be 'packed', with no large gaps between planets.
Neutron Inelastic Scattering Study of Liquid Argon
Energy Technology Data Exchange (ETDEWEB)
Skoeld, K; Rowe, J M; Ostrowski, G [Solid State Science Div., Argonne National Laboratory, Argonne, Illinois (US); Randolph, P D [Nuclear Technology Div., Idaho Nuclear Corporation, Idaho Falls, Idaho (US)
1972-02-15
The inelastic scattering functions for liquid argon have been measured at 85.2 K. The coherent scattering function was obtained from a measurement on pure A-36 and the incoherent function was derived from the result obtained from the A-36 sample and the result obtained from a mixture of A-36 and A-40 for which the scattering is predominantly incoherent. The data, which are presented as smooth scattering functions at constant values of the wave vector transfer in the range 10 - 44/nm, are corrected for multiple scattering contributions and for resolution effects. Such corrections are shown to be essential in the derivation of reliable scattering functions from neutron scattering data. The incoherent data are compared to recent molecular dynamics results and the mean square displacement as a function of time is derived. The coherent data are compared to molecular dynamics results and also, briefly, to some recent theoretical models
Radiation scatter apparatus and method
International Nuclear Information System (INIS)
Molbert, J. L.; Riddle, E. R.
1985-01-01
A radiation scatter gauge includes multiple detector locations for developing separate and independent sets of data from which multiple physical characteristics of a thin material and underlying substrate may be determined. In an illustrated embodiment, the apparatus and method of the invention are directed to determining characteristics of resurfaced pavement by nondestructive testing. More particularly, the density and thickness of a thin asphalt overlay and the density of the underlying pavement may be determined
Ouyang, Yilan; Zeng, Yangyang; Yi, Lin; Tang, Hong; Li, Duxin; Linhardt, Robert J; Zhang, Zhenqing
2017-11-03
Heparin, a highly sulfated glycosaminoglycan, has been used as a clinical anticoagulant over 80 years. Low molecular weight heparins (LMWHs), heparins partially depolymerized using different processes, are widely used as clinical anticoagulants. Qualitative molecular weight (MW) and quantitative mass content analysis are two important factors that contribute to LMWH quality control. Size exclusion chromatography (SEC), relying on multiple angle laser scattering (MALS)/refractive index (RI) detectors, has been developed for accurate analysis of heparin MW in the absence of standards. However, the cations, which ion-pair with the anionic polysaccharide chains of heparin and LMWHs, had not been considered in previous reports. In this study, SEC with MALS/RI and inductively coupled plasma/mass spectrometry detectors were used in a comprehensive analytical approach taking both anionic polysaccharide and ion-paired cations heparin products. This approach was also applied to quantitative analysis of heparin and LMWHs. Full profiles of MWs and mass recoveries for three commercial heparin/LMWH products, heparin sodium, enoxaparin sodium and nadroparin calcium, were obtained and all showed higher MWs than previously reported. This important improvement more precisely characterized the MW properties of heparin/LMWHs and potentially many other anionic polysaccharides. Copyright © 2017 Elsevier B.V. All rights reserved.
Chaotic scattering and quantum dynamics
International Nuclear Information System (INIS)
Doron, Eyal.
1992-11-01
The main concern of this thesis is the application of the semiclassical approximation to quantum chaotic scattering systems. We deal with two separate, although interconnected, subjects. The first subject dealt with is the semiclassical characterization of the fluctuations of the S matrix. A particular important parameter is the magnetic field B, and we show how the correlation length and line shape of S matrix elements under a change of B may be derived. An effect which is present in many physical wave systems is absorption of energy flux. We show how absorption affects both the reflectivity and the scattering phase and time delay of a scattering system. In the second part of the thesis, we show how the formalism and results obtained from chaotic scattering can be applied to the investigation of closed chaotic systems, and in particular to chaotic billiards. The semiclassical expansion for billiards is presented. In the last part of the thesis we deal with the statistics of S matrices of chaotic scattering systems. The main message of this work is that scattering matrix, and its classical counterpart the Poincare Scattering Map can be used to yield a powerful formulation of the quantum mechanical dynamics of bounded systems. (author)
International Nuclear Information System (INIS)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner
2012-01-01
The following topics are dealt with: Neutron scattering in contemporary research, 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)
SAR Polarimetric Scattering from Natural Terrains
2017-02-17
land surfaces. In addition, NMM3D will also be useful for C-, X-, and Ku-bands. NMM3D results will also be implemented in the NASA Earth Observing...unlimited. (3) Multiple Scattering Effects with Cyclical Terms in Active Remote Sensing of Vegetated Surface Using Vector Radiative Transfer Theory...IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 9, pp. 1414-1429 (2016)) The multiple scattering and
Elastic wave scattering from multiple voids (porosity)
International Nuclear Information System (INIS)
Thompson, D.O.; Rose, J.H.; Thompson, R.B.; Wormley, S.J.
1983-01-01
This paper describes the development of an ultrasonic backscatter measurement technique which provides a convenient way to determine certain characteristics of a distribution of voids (porosity) in materials. A typical ultrasonic sample prepared by placing the ''frit'' in a crucible in an RF induction heater is shown. The results of the measurements were Fourier transformed into an amplitude-frequency description, and were then deconvolved with the transducer response function. Several properties needed to characterize a void distribution are obtained from the experimental results, including average void size, the spatial extent of the voids region, the average void separation, and the volume fraction of material contained in the void distribution. A detailed comparison of values obtained from the ultrasonic measurements with visually determined results is also given
Relativistic multiple scattering X-alpha calculations
International Nuclear Information System (INIS)
Chermette, H.; Goursot, A.
1986-01-01
The necessity to include self-consistent relativistic corrections in molecular calculations has been pointed out for all compounds involving heavy atoms. Most of the changes in the electronic properties are due to the mass-velocity and the so-called Darwin terms so that the use of Wood and Boring's Hamiltonian is very convenient for this purpose as it can be easily included in MSXalpha programs. Although the spin orbit operator effects are only obtained by perturbation theory, the results compare fairly well with experiment and with other relativistic calculations, namely Hartree-Fock-Slater calculations
Single and Multiple Scattered Solar Radiation
1982-08-30
quivalento of ANCLST and THrST I - oI O Caculate IIS I the rat in va at Zt FANC f(SltNZEN .PTIlZlNJ SCIANG of PTINZF N ) Figure 1,5 Flow chart of function...1.0 gene Va itv qna1,drntn re WCv ights t7 or OY1r011 2- LO 10 bdMv I)o j1!LS . The rslI L I 11g WCe igIILS C arco us ed to r a Gauss ,ian q 11/id
Filling a gap in multiple scattering theory
Hovenier, J.W.; Stam, D.M.; Videen, G.; et al,
2007-01-01
Horizontal incidence and reflection by a plane-parallel atmosphere is investigated. A peculiar discontinuity of the reflected intensity is discussed. Several interesting properties of the bidirectional reflection function are presented, together with some applications.
Cerchione, Claudio; Nappi, Davide; Pareto, Anna E; Romano, Alessandra; Martinelli, Vincenzo; Picardi, Marco; Pane, Fabrizio; Catalano, Lucio
2018-04-01
Renal impairment (RI) is a relevant complication of patients affected by multiple myeloma (MM); it can be present in up to 30-35% of newly diagnosed MM and is linked to a poor outcome. However, early recognition and early treatment with novel agents can overcome the negative impact of RI and even reverse kidney damage in most cases. Lenalidomide, available as an oral compound, is an immunomodulatory drug with both antiproliferative and immunomodulatory activity that is largely used in the management of MM. Dose reduction is mandatory in RI; however, there is no theoretical assumption against the possibility that protracting the time of full standard doses can be equally effective and tolerated by patients requiring reduced doses. In this report, we describe our retrospective experience, in 18 patients, with the administration of lenalidomide 25 mg every other day for patients with MM and RI. The overall response ratio was 66.5%. More than half (61.1%) of the patients had a renal response. The median progression-free survival was 8 months (range: 3-18 months). No serious adverse event occurred during treatment, and it was never necessary to disrupt or delay treatment for toxicity. These preliminary observations point to a significant therapeutic effect of lenalidomide, at the dose of 25 mg every other day for 21 days, with logistic and economic advantages. However, these results should be validated by controlled studies involving larger numbers of patients.
Khalili, Mohammad; Azimi, Amirreza; Izadi, Vajihe; Eghtesadi, Shahryar; Mirshafiey, Abbas; Sahraian, Mohamad Ali; Motevalian, Abbas; Norouzi, Abbas; Sanoobar, Meisam; Eskandari, Ghazaleh; Farhoudi, Mehdi; Amani, Firouz
2014-01-01
A limited amount of data exists regarding the effect of lipoic acid (LA), an oral antioxidant supplement, on cytokine profiles among multiple sclerosis (MS) patients. We aimed to assess the effect of daily consumption of LA on the cytokine profiles in MS patients. In this double-blind, placebo-controlled, randomized clinical trial, 52 relapsing-remitting MS patients with an age range of 18-50 years were recruited into 2 groups: LA consumption (1,200 mg/day) or placebo. Patients followed their prescribed supplements for 12 weeks. Fasting blood samples for cytokine profile measurement were collected at baseline and after the intervention. Anthropometric parameters were measured based on the standard guidelines. INF-γ, ICAM-1, TGF-β and IL-4 were significantly reduced in the LA group compared to the placebo group [(INF-γ: 0.82 ± 0.2 vs. 0.2 ± 0.2 pg/ml, p consumption of 1,200 mg LA per day beneficially affects several inflammatory cytokines including INF-γ, ICAM-1 TGF-β and IL-4. Further investigations are needed to verify the beneficial role of LA on other cytokine profiles among MS patients.
Kim, Sunmi; Kang, Jung-Youn; Cho, Dong-Im; Park, Ji Hye; Kim, Soo Young
2004-10-01
Phytohormone abscisic acid (ABA) regulates stress-responsive gene expression during vegetative growth, which is mediated largely by cis-elements sharing the ACGTGGC consensus. Although many transcription factors are known to bind the elements in vitro, only a few have been demonstrated to have in vivo functions and their specific roles in ABA/stress responses are mostly unknown. Here, we report that ABF2, an ABF subfamily member of bZIP proteins interacting with the ABA-responsive elements, is involved in ABA/stress responses. Its overexpression altered ABA sensitivity, dehydration tolerance, and the expression levels of ABA/stress-regulated genes. Furthermore, ABF2 overexpression promoted glucose-induced inhibition of seedling development, whereas its mutation impaired glucose response. The reduced sugar sensitivity was not observed with mutants of two other ABF family members, ABF3 and ABF4. Instead, these mutants displayed defects in ABA, salt, and dehydration responses, which were not observed with the abf2 mutant. Our data indicate distinct roles of ABF family members: whereas ABF3 and ABF4 play essential roles in ABA/stress responses, ABF2 is required for normal glucose response. We also show that ABF2 overexpression affects multiple stress tolerance.
Energy Technology Data Exchange (ETDEWEB)
Cole, Jacqueline M.; Cramer, Alisha J.; Shastri, Sarvjit D.; Mukaddem, Karim T.; Newport, Robert J
2018-04-26
A Gd K-edge anomalous X-ray scattering (AXS) study is performed on the rare-earth (R) phosphate glass, (Gd2O3)0.230(P2O5)0.770, in order to determine Gd…Gd separations in its local structure. The minimum rare-earth separation is of particular interest given that the optical properties of these glasses can quench when rare-earth ions become too close to each other. To this end, a weak Gd…Gd pairwise correlation is located at 4.2(1) Å which is representative of a meta-phosphate R…R separation. More intense first neighbor Gd…Gd pairwise correlations are found at the larger radial distributions, 4.8(1) Å, 5.1(1) Å and 5.4(1) Å. These reflect a mixed ultra-phosphate and meta-phosphate structural character, respectively. A second neighbor Gd…Gd pairwise correlation lies at 6.6(1) Å which is indicative of meta-phosphate structures. Meta- and ultra-phosphate classifications are made by comparing the R…R separations against those of rare-earth phosphate crystal structures, R(PO3)3 and RP5O14 respectively, or difference pair distribution function (PDF) features determined on similar glasses using difference neutron scattering methods. The local structure of this glass is therefore found to display multiple rare-earth ion environments, presumably because its composition lies between these two stoichiometric formulae. These Gd…Gd separations are well resolved in the PDFs that represent the AXS signal. Indeed, the spatial resolution is so good that it also enables the identification of R…X (X = R, P, O) pairwise correlations up to r ~ 9 Å; their average separations lie at r ~ 7.1(1) Å, 7.6(1) Å 7.9(1) Å, 8.4(1) Å and 8.7(1) Å. This is the first report of a Gd K-edge AXS study on an amorphous material. Its demonstrated ability to characterize the local structure of a glass up to such a long-range of r, heralds exciting prospects for AXS studies on other ternary non-crystalline materials. However, the technical challenge of such an experiment
International Nuclear Information System (INIS)
Groves-Kirkby, Christopher J.; Denman, Antony R.; Campbell, Jackie; Crockett, Robin G.M.; Phillips, Paul S.; Rogers, Stephen
2016-01-01
Multiple Sclerosis has been postulated to be triggered by elevated radon gas levels. • MS incidence analysed from 20 million person-years monitoring in radon affected areas. • Linear regression slope of ERR against radon level is 0.22 per 100 Bq·m −3 (R 2 = 0.25). • Linear fit 95% CI encompasses the Null Hypothesis and is therefore not significant. • Potential confounding processes are shown to have minimal impact on the results.
Exact and approximate multiple diffraction calculations
International Nuclear Information System (INIS)
Alexander, Y.; Wallace, S.J.; Sparrow, D.A.
1976-08-01
A three-body potential scattering problem is solved in the fixed scatterer model exactly and approximately to test the validity of commonly used assumptions of multiple scattering calculations. The model problem involves two-body amplitudes that show diffraction-like differential scattering similar to high energy hadron-nucleon amplitudes. The exact fixed scatterer calculations are compared to Glauber approximation, eikonal-expansion results and a noneikonal approximation
Bidirectional optical scattering facility
Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI)The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from a...
Scattered radiation in fan beam imaging systems
International Nuclear Information System (INIS)
Johns, P.C.; Yaffe, M.
1982-01-01
Scatter-to-primary energy fluence ratios (S/P) have been studied for fan x-ray beams as used in CT scanners and slit projection radiography systems. The dependence of S/P on phantom diameter, distance from phantom to image receptor, and kilovoltage is presented. An empirical equation is given that predicts S/P over a wide range of fan beam imaging configurations. For CT body scans on a 4th-generation machine, S/P is approximately 5%. Scattered radiation can produce a significant cupping artefact in CT images which is similar to that due to beam hardening. When multiple slices are used in scanned slit radiography, they can be arranged such that the increase in S/P is negligible. Calculations of scatter-to-primary ratios for first order scattering showed that for fan beams the contribution of coherent scatter is comparable to or greater than that of incoherent first scatter
Classical trajectory in non-relativistic scattering
International Nuclear Information System (INIS)
Williams, A.C.
1978-01-01
With the statistical interpretation of quantum mechanics as a guide, the classical trajectory is incorporated into quantum scattering theory. The Feynman path integral formalism is used as a starting point, and classical transformation theory is applied to the phase of the wave function so derived. This approach is then used to derive an expression for the scattering amplitude for potential scattering. It is found that the amplitude can be expressed in an impact parameter representation similar to the Glauber formalism. Connections are then made to the Glauber approximation and to semiclassical approximations derived from the Feynman path integral formalism. In extending this analysis to projectile-nucleus scattering, an approximation scheme is given with the first term being the same as in Glauber's multiple scattering theory. Higher-order approximations, thus, are found to give corrections to the fixed scatterer form of the impulse approximation inherent in the Glauber theory
On the analysis of Deep Inelastic Neutron Scattering Experiments
International Nuclear Information System (INIS)
Blostein, J.J.; Dawidowski, J.; Granada, J.R.
2001-01-01
We analyze the different steps that must be followed for data processing in Deep Inelastic Neutron Scattering Experiments. Firstly we discuss to what extent multiple scattering effects can affect the measured peak shape, concluding the an accurate calculation of these effects must be performed to extract the desired effective temperature from the experimental data. We present a Monte Carlo procedure to perform these corrections. Next, we focus our attention on experiments performed on light nuclei. We examine cases in which the desired information is obtained from the observed peak areas, and we analyze the procedure to obtain an effective temperature from the experimental peaks. As a consequence of the results emerging from those cases we trace the limits of validity of the convolution formalism usually employed, and propose a different treatment of the experimental data for this kind of measurements. (author)
On the analysis of Deep Inelastic Neutron Scattering Experiments
Energy Technology Data Exchange (ETDEWEB)
Blostein, J.J.; Dawidowski, J.; Granada, J.R. [Comision Nacional de Energia Atomica and CONICET, Centro Atomico Bariloche and Instituto Balseiro, Bariloche (Argentina)
2001-03-01
We analyze the different steps that must be followed for data processing in Deep Inelastic Neutron Scattering Experiments. Firstly we discuss to what extent multiple scattering effects can affect the measured peak shape, concluding the an accurate calculation of these effects must be performed to extract the desired effective temperature from the experimental data. We present a Monte Carlo procedure to perform these corrections. Next, we focus our attention on experiments performed on light nuclei. We examine cases in which the desired information is obtained from the observed peak areas, and we analyze the procedure to obtain an effective temperature from the experimental peaks. As a consequence of the results emerging from those cases we trace the limits of validity of the convolution formalism usually employed, and propose a different treatment of the experimental data for this kind of measurements. (author)
Characterization of porous materials by small-angle scattering
Indian Academy of Sciences (India)
With the availability of ultra small-angle scattering instruments, one can investigate porous materials in the sub-micron length scale. Because of the increased accessible length scale vis-a-vis the multiple scattering effect, conventional data analysis procedures based on single scattering approximation quite often fail.
Dynamics of liquid N2 studied by neutron inelastic scattering
DEFF Research Database (Denmark)
Pedersen, Karen Schou; Carneiro, Kim; Hansen, Flemming Yssing
1982-01-01
Neutron inelastic-scattering data from liquid N2 at wave-vector transfer κ between 0.18 and 2.1 Å-1 and temperatures ranging from T=65-77 K are presented. The data are corrected for the contribution from multiple scattering and incoherent scattering. The resulting dynamic structure factor S (κ,ω)...
Neutrino coherent forward scattering and its index of refraction
International Nuclear Information System (INIS)
Liu, J.
1992-01-01
It is pointed out that, if neutrinos are to maintain coherence over the required distance for the Mikheyev-Smirnov-Wolfenstein solutions to the solar-neutrino problem, effects arising from neutrino multiple scattering must be considered. We give a simple derivation for the neutrino index of refraction that takes into account this effect. The same method is also shown to be useful for situations with varying matter densities and neutrino mixing. We also examine the question whether the coherence of propagating neutrinos in matter will be affected by switching on an external magnetic field, assuming neutrinos have a large magnetic moment
Iserbyt, Peter; Schouppe, Gilles; Charlier, Nathalie
2015-04-01
Research investigating lifeguards' performance of Basic Life Support (BLS) with Automated External Defibrillator (AED) is limited. Assessing simulated BLS/AED performance in Flemish lifeguards and identifying factors affecting this performance. Six hundred and sixteen (217 female and 399 male) certified Flemish lifeguards (aged 16-71 years) performed BLS with an AED on a Laerdal ResusciAnne manikin simulating an adult victim of drowning. Stepwise multiple linear regression analysis was conducted with BLS/AED performance as outcome variable and demographic data as explanatory variables. Mean BLS/AED performance for all lifeguards was 66.5%. Compression rate and depth adhered closely to ERC 2010 guidelines. Ventilation volume and flow rate exceeded the guidelines. A significant regression model, F(6, 415)=25.61, p<.001, ES=.38, explained 27% of the variance in BLS performance (R2=.27). Significant predictors were age (beta=-.31, p<.001), years of certification (beta=-.41, p<.001), time on duty per year (beta=-.25, p<.001), practising BLS skills (beta=.11, p=.011), and being a professional lifeguard (beta=-.13, p=.029). 71% of lifeguards reported not practising BLS/AED. Being young, recently certified, few days of employment per year, practising BLS skills and not being a professional lifeguard are factors associated with higher BLS/AED performance. Measures should be taken to prevent BLS/AED performances from decaying with age and longer certification. Refresher courses could include a formal skills test and lifeguards should be encouraged to practise their BLS/AED skills. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Kaown, Dugin; Koh, Eun-Hee; Mayer, Bernhard; Kim, Heejung; Park, Dong Kyu; Park, Byeong-Hak; Lee, Kang-Kun
2018-01-01
The extent of denitrification in a small agricultural area near a river in Yangpyeong, South Korea, was determined using multiple isotopes, groundwater age, and physicochemical data for groundwater. The shallow groundwater at one monitoring site had high concentrations of NO3-N (74-83 mg L-1). The δ15N-NO3 values for groundwater in the study area ranged between +9.1 and +24.6‰ in June 2014 and +12.2 to +21.6‰ in October 2014. High δ15N-NO3 values (+10.7 to +12.5‰) in both sampling periods indicated that the high concentrations of nitrate in the groundwater originated from application of organic fertilizers and manure. In the northern part of the study area, some groundwater samples showed elevated δ15N-NO3 and δ18O-NO3 values, which suggest that nitrate was removed from the groundwater via denitrification, with N isotope enrichment factors ranging between -4.8 and -7.9‰ and O isotope enrichment factors varying between -3.8 and -4.9‰. Similar δD and δ18O values of the surface water and groundwater in the south appear to indicate that groundwater in that area was affected by surface-water infiltration. The mean residence times (MRTs) of groundwater showed younger ages in the south (10-20 years) than in the north (20-30 years). Hence, it was concluded that denitrification processes under anaerobic conditions with longer groundwater MRT in the northern part of the study area removed considerable amounts of nitrate. This study demonstrates that multi-isotope data combined with physicochemical data and age-dating information can be effectively applied to characterize nitrate contaminant sources and attenuation processes.
Cooperative scattering of scalar waves by optimized configurations of point scatterers
Schäfer, Frank; Eckert, Felix; Wellens, Thomas
2017-12-01
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.
Practical model for the calculation of multiply scattered lidar returns
International Nuclear Information System (INIS)
Eloranta, E.W.
1998-01-01
An equation to predict the intensity of the multiply scattered lidar return is presented. Both the scattering cross section and the scattering phase function can be specified as a function of range. This equation applies when the cloud particles are larger than the lidar wavelength. This approximation considers photon trajectories with multiple small-angle forward-scattering events and one large-angle scattering that directs the photon back toward the receiver. Comparisons with Monte Carlo simulations, exact double-scatter calculations, and lidar data demonstrate that this model provides accurate results. copyright 1998 Optical Society of America
Energy Technology Data Exchange (ETDEWEB)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner [eds.
2010-07-01
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)
International Nuclear Information System (INIS)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner
2013-01-01
The following topics are dealt with: Neutron sources, symmetry of crystals, nanostructures investigated by small-angle neutron scattering, structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic neutron scattering, strongly correlated electrons, polymer dynamics, applications of neutron scattering. (HSI)
International Nuclear Information System (INIS)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner
2010-01-01
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)
Polarization recovery through scattering media.
de Aguiar, Hilton B; Gigan, Sylvain; Brasselet, Sophie
2017-09-01
The control and use of light polarization in optical sciences and engineering are widespread. Despite remarkable developments in polarization-resolved imaging for life sciences, their transposition to strongly scattering media is currently not possible, because of the inherent depolarization effects arising from multiple scattering. We show an unprecedented phenomenon that opens new possibilities for polarization-resolved microscopy in strongly scattering media: polarization recovery via broadband wavefront shaping. We demonstrate focusing and recovery of the original injected polarization state without using any polarizing optics at the detection. To enable molecular-level structural imaging, an arbitrary rotation of the input polarization does not degrade the quality of the focus. We further exploit the robustness of polarization recovery for structural imaging of biological tissues through scattering media. We retrieve molecular-level organization information of collagen fibers by polarization-resolved second harmonic generation, a topic of wide interest for diagnosis in biomedical optics. Ultimately, the observation of this new phenomenon paves the way for extending current polarization-based methods to strongly scattering environments.
Scattering Correction For Image Reconstruction In Flash Radiography
International Nuclear Information System (INIS)
Cao, Liangzhi; Wang, Mengqi; Wu, Hongchun; Liu, Zhouyu; Cheng, Yuxiong; Zhang, Hongbo
2013-01-01
Scattered photons cause blurring and distortions in flash radiography, reducing the accuracy of image reconstruction significantly. The effect of the scattered photons is taken into account and an iterative deduction of the scattered photons is proposed to amend the scattering effect for image restoration. In order to deduct the scattering contribution, the flux of scattered photons is estimated as the sum of two components. The single scattered component is calculated accurately together with the uncollided flux along the characteristic ray, while the multiple scattered component is evaluated using correction coefficients pre-obtained from Monte Carlo simulations.The arbitrary geometry pretreatment and ray tracing are carried out based on the customization of AutoCAD. With the above model, an Iterative Procedure for image restORation code, IPOR, is developed. Numerical results demonstrate that the IPOR code is much more accurate than the direct reconstruction solution without scattering correction and it has a very high computational efficiency
Scattering Correction For Image Reconstruction In Flash Radiography
Energy Technology Data Exchange (ETDEWEB)
Cao, Liangzhi; Wang, Mengqi; Wu, Hongchun; Liu, Zhouyu; Cheng, Yuxiong; Zhang, Hongbo [Xi' an Jiaotong Univ., Xi' an (China)
2013-08-15
Scattered photons cause blurring and distortions in flash radiography, reducing the accuracy of image reconstruction significantly. The effect of the scattered photons is taken into account and an iterative deduction of the scattered photons is proposed to amend the scattering effect for image restoration. In order to deduct the scattering contribution, the flux of scattered photons is estimated as the sum of two components. The single scattered component is calculated accurately together with the uncollided flux along the characteristic ray, while the multiple scattered component is evaluated using correction coefficients pre-obtained from Monte Carlo simulations.The arbitrary geometry pretreatment and ray tracing are carried out based on the customization of AutoCAD. With the above model, an Iterative Procedure for image restORation code, IPOR, is developed. Numerical results demonstrate that the IPOR code is much more accurate than the direct reconstruction solution without scattering correction and it has a very high computational efficiency.
Energy Technology Data Exchange (ETDEWEB)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)
2010-07-01
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)
International Nuclear Information System (INIS)
Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner
2010-01-01
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)
Directory of Open Access Journals (Sweden)
Nancy L Saccone
2010-08-01
Full Text Available Recently, genetic association findings for nicotine dependence, smoking behavior, and smoking-related diseases converged to implicate the chromosome 15q25.1 region, which includes the CHRNA5-CHRNA3-CHRNB4 cholinergic nicotinic receptor subunit genes. In particular, association with the nonsynonymous CHRNA5 SNP rs16969968 and correlates has been replicated in several independent studies. Extensive genotyping of this region has suggested additional statistically distinct signals for nicotine dependence, tagged by rs578776 and rs588765. One goal of the Consortium for the Genetic Analysis of Smoking Phenotypes (CGASP is to elucidate the associations among these markers and dichotomous smoking quantity (heavy versus light smoking, lung cancer, and chronic obstructive pulmonary disease (COPD. We performed a meta-analysis across 34 datasets of European-ancestry subjects, including 38,617 smokers who were assessed for cigarettes-per-day, 7,700 lung cancer cases and 5,914 lung-cancer-free controls (all smokers, and 2,614 COPD cases and 3,568 COPD-free controls (all smokers. We demonstrate statistically independent associations of rs16969968 and rs588765 with smoking (mutually adjusted p-values<10(-35 and <10(-8 respectively. Because the risk alleles at these loci are negatively correlated, their association with smoking is stronger in the joint model than when each SNP is analyzed alone. Rs578776 also demonstrates association with smoking after adjustment for rs16969968 (p<10(-6. In models adjusting for cigarettes-per-day, we confirm the association between rs16969968 and lung cancer (p<10(-20 and observe a nominally significant association with COPD (p = 0.01; the other loci are not significantly associated with either lung cancer or COPD after adjusting for rs16969968. This study provides strong evidence that multiple statistically distinct loci in this region affect smoking behavior. This study is also the first report of association between rs588765
A Theory of Exoplanet Transits with Light Scattering
Energy Technology Data Exchange (ETDEWEB)
Robinson, Tyler D., E-mail: tydrobin@ucsc.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
2017-02-20
Exoplanet transit spectroscopy enables the characterization of distant worlds, and will yield key results for NASA's James Webb Space Telescope . However, transit spectra models are often simplified, omitting potentially important processes like refraction and multiple scattering. While the former process has seen recent development, the effects of light multiple scattering on exoplanet transit spectra have received little attention. Here, we develop a detailed theory of exoplanet transit spectroscopy that extends to the full refracting and multiple scattering case. We explore the importance of scattering for planet-wide cloud layers, where the relevant parameters are the slant scattering optical depth, the scattering asymmetry parameter, and the angular size of the host star. The latter determines the size of the “target” for a photon that is back-mapped from an observer. We provide results that straightforwardly indicate the potential importance of multiple scattering for transit spectra. When the orbital distance is smaller than 10–20 times the stellar radius, multiple scattering effects for aerosols with asymmetry parameters larger than 0.8–0.9 can become significant. We provide examples of the impacts of cloud/haze multiple scattering on transit spectra of a hot Jupiter-like exoplanet. For cases with a forward and conservatively scattering cloud/haze, differences due to multiple scattering effects can exceed 200 ppm, but shrink to zero at wavelength ranges corresponding to strong gas absorption or when the slant optical depth of the cloud exceeds several tens. We conclude with a discussion of types of aerosols for which multiple scattering in transit spectra may be important.
International Nuclear Information System (INIS)
Ahn, Ji Eun; Do, Kyung Hyun; Chae, Eun Jin; Seo, Joon Beom; Lee, Jin Seong; Song, Koun Sik; Song, Jae Wo; Kim, Kyu Rae; Lim, Tae Hwan
2007-01-01
A benign metastasizing leiomyoma is a rare condition that affects women with a history of uterine leiomyoma, usually after a myomectomy or hysterectomy. Typical radiographic findings include well-circumscribed solitary or multiple pulmonary nodules ranging from a few millimeters to several centimeters in diameter and scattered among the normal interstitium. We report a case of a benign metastasizing leiomyoma that manifested with multiple cavitary nodules in a 46-year-old woman with no previous history of a myomectomy or hysterectomy
Energy Technology Data Exchange (ETDEWEB)
Ahn, Ji Eun; Do, Kyung Hyun; Chae, Eun Jin; Seo, Joon Beom; Lee, Jin Seong; Song, Koun Sik; Song, Jae Wo; Kim, Kyu Rae; Lim, Tae Hwan [University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of)
2007-09-15
A benign metastasizing leiomyoma is a rare condition that affects women with a history of uterine leiomyoma, usually after a myomectomy or hysterectomy. Typical radiographic findings include well-circumscribed solitary or multiple pulmonary nodules ranging from a few millimeters to several centimeters in diameter and scattered among the normal interstitium. We report a case of a benign metastasizing leiomyoma that manifested with multiple cavitary nodules in a 46-year-old woman with no previous history of a myomectomy or hysterectomy.
A library least-squares approach for scatter correction in gamma-ray tomography
International Nuclear Information System (INIS)
Meric, Ilker; Anton Johansen, Geir; Valgueiro Malta Moreira, Icaro
2015-01-01
Scattered radiation is known to lead to distortion in reconstructed images in Computed Tomography (CT). The effects of scattered radiation are especially more pronounced in non-scanning, multiple source systems which are preferred for flow imaging where the instantaneous density distribution of the flow components is of interest. In this work, a new method based on a library least-squares (LLS) approach is proposed as a means of estimating the scatter contribution and correcting for this. The validity of the proposed method is tested using the 85-channel industrial gamma-ray tomograph previously developed at the University of Bergen (UoB). The results presented here confirm that the LLS approach can effectively estimate the amounts of transmission and scatter components in any given detector in the UoB gamma-ray tomography system. - Highlights: • A LLS approach is proposed for scatter correction in gamma-ray tomography. • The validity of the LLS approach is tested through experiments. • Gain shift and pulse pile-up affect the accuracy of the LLS approach. • The LLS approach successfully estimates scatter profiles
Plane wave scattering by bow-tie posts
Lech, Rafal; Mazur, Jerzy
2004-04-01
The theory of scattering in free space by a novel structure of a two-dimensional dielectric-metallic post is developed with the use of a combination of a modified iterative scattering procedure and an orthogonal expansion method. The far scattered field patterns for open structures are derived. The rotation of the post affects its scattered field characteristic, which permits to make adjustments in characteristic of the posts arrays.
High-energy proton scattering on nuclei
Klovning, A; Schlüpmann, K
1973-01-01
High-energy proton scattering on Be, C, Cu and Pb targets is studied using a single-arm spectrometer. The projectile momenta were 19 and 24 GeV/c, the square of the four-momentum transfer varied from t=0.1 to t =4.4 GeV/sup 2/. Momentum distributions of scattered protons are recorded in the high-momentum range. An application of multiple- scattering theory yielded agreement of calculation and experimental results to within a +or-30% uncertainty of the former. (15 refs).
Neutron scattering from fractals
DEFF Research Database (Denmark)
Kjems, Jørgen; Freltoft, T.; Richter, D.
1986-01-01
The scattering formalism for fractal structures is presented. Volume fractals are exemplified by silica particle clusters formed either from colloidal suspensions or by flame hydrolysis. The determination of the fractional dimensionality through scattering experiments is reviewed, and recent small...
Scatter from optical components
International Nuclear Information System (INIS)
Stover, J.C.
1989-01-01
This book is covered under the following topics: measurement and analysis techniques; BRDF standards, comparisons, and anomalies; scatter measurement of several materials; scatter from contaminations; and optical system contamination: effects, measurement, and control
Angular distribution of 662keV multiply-Compton scattered gamma rays in copper
International Nuclear Information System (INIS)
Singh, Manpreet; Singh, Gurvinderjit; Sandhu, B.S.; Singh, Bhajan
2007-01-01
The angular distribution of multiple Compton scattering of 662keV gamma photons, obtained from six Curie 137 Cs source, incident on copper scatterer of varying thickness is studied experimentally in both the forward and backward hemispheres. The scattered photons are detected by a 51mmx51mm NaI(Tl) scintillation detector. The full-energy peak corresponding to singly scattered events is reconstructed analytically. We observe that the numbers of multiply scattered events, having same energy as in the singly scattered distribution, first increases with increase in target thickness and then saturate. The optimum thickness at which the multiply scattered events saturate is determined at different scattering angles
Multiple intracranial hydatid cysts: MR findings
International Nuclear Information System (INIS)
Pumar, J.; Alvarez, M.; Leira, R.; Prieto, J.M.; Arrojo, L.; Pereira, J.; Vidal, J.
1992-01-01
Multiple intracranial hydatid cysts are uncommon and usually localized in the supratentorial compartment. We report a case studied by CT and MR of multiple intracranial hydatid cysts scattered in various anatomic sites: supratentorial, infratentorial and also intraventricular. (orig.)
Multiplicity distributions in inelastic reactions on nuclei
Caneschi, L; Schwimmer, A
1976-01-01
The multiplicity distribution of the number of knocked-out nucleons and the correlation of the former with the multiplicity of the produced mesons, in inelastic particle-nucleus scattering, are computed.
Scattering influence in mammographic image
International Nuclear Information System (INIS)
Poletti, Martin Eduardo; Almeida, Adelaide de
1996-01-01
The quantification of mammographic images affected by scattered radiation is studied. The average glandular dose as a function of kVp and breast thickness for breast composition 50/50% is also evaluated. The results show that the contrast decreases with increasing of kVp and breast thickness, and the average glandular dose increase with increasing breast thickness and decreases with increasing kVp
Electron scattering from tetrahydrofuran
International Nuclear Information System (INIS)
Fuss, M C; Sanz, A G; García, G; Muñoz, A; Oller, J C; Blanco, F; Do, T P T; Brunger, M J; Almeida, D; Limão-Vieira, P
2012-01-01
Electron scattering from Tetrahydrofuran (C 4 H 8 O) was investigated over a wide range of energies. Following a mixed experimental and theoretical approach, total scattering, elastic scattering and ionization cross sections as well as electron energy loss distributions were obtained.
International Nuclear Information System (INIS)
Doll, P.
1990-02-01
Neutron-proton scattering as fundamental interaction process below and above hundred MeV is discussed. Quark model inspired interactions and phenomenological potential models are described. The seminar also indicates the experimental improvements for achieving new precise scattering data. Concluding remarks indicate the relevance of nucleon-nucleon scattering results to finite nuclei. (orig.) [de
Home Page | Facilities | Reference | Software | Conferences | Announcements | Mailing Lists Neutron Scattering Banner Neutron Scattering Software A new portal for neutron scattering has just been established sets KUPLOT: data plotting and fitting software ILL/TAS: Matlab probrams for analyzing triple axis data
International Nuclear Information System (INIS)
Lovesey, S.W.
1987-05-01
The report reviews, at an introductory level, the theory of photon scattering from condensed matter. Magnetic scattering, which arises from first-order relativistic corrections to the Thomson scattering amplitude, is treated in detail and related to the corresponding interaction in the magnetic neutron diffraction amplitude. (author)
Roessli, B.; Böni, P.
2000-01-01
The technique of polarized neutron scattering is reviewed with emphasis on applications. Many examples of the usefulness of the method in various fields of physics are given like the determination of spin density maps, measurement of complex magnetic structures with spherical neutron polarimetry, inelastic neutron scattering and separation of coherent and incoherent scattering with help of the generalized XYZ method.
Double hard scattering without double counting
Energy Technology Data Exchange (ETDEWEB)
Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gaunt, Jonathan R. [VU Univ. Amsterdam (Netherlands). NIKHEF Theory Group; Schoenwald, Kay [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2017-02-15
Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.
Double hard scattering without double counting
International Nuclear Information System (INIS)
Diehl, Markus; Gaunt, Jonathan R.
2017-02-01
Double parton scattering in proton-proton collisions includes kinematic regions in which two partons inside a proton originate from the perturbative splitting of a single parton. This leads to a double counting problem between single and double hard scattering. We present a solution to this problem, which allows for the definition of double parton distributions as operator matrix elements in a proton, and which can be used at higher orders in perturbation theory. We show how the evaluation of double hard scattering in this framework can provide a rough estimate for the size of the higher-order contributions to single hard scattering that are affected by double counting. In a numeric study, we identify situations in which these higher-order contributions must be explicitly calculated and included if one wants to attain an accuracy at which double hard scattering becomes relevant, and other situations where such contributions may be neglected.
Magnetic X-Ray Scattering with Synchrotron Radiation
DEFF Research Database (Denmark)
Moncton, D. E.; Gibbs, D.; Bohr, Jakob
1986-01-01
With the availability of high-brilliance synchrotron radiation from multiple wigglers, magnetic X-ray scattering has become a powerful new probe of magnetic structure and phase transitions. Similar to the well-established magnetic neutron scattering technique, magnetic X-ray scattering methods have...... many complementary advantages. A brief review is presented of the history of magnetic X-ray scattering as well as recent results obtained in studies of the rare-earth magnet holmium with emphasis on instrumentational aspects. In particular, the development of a simple polarization analyzer...... to distinguish charge and magnetic scattering is described....
DISCUS, Neutron Single to Double Scattering Ratio in Inelastic Scattering Experiment by Monte-Carlo
International Nuclear Information System (INIS)
Johnson, M.W.
1993-01-01
1 - Description of problem or function: DISCUS calculates the ratio of once-scattered to twice-scattered neutrons detected in an inelastic neutron scattering experiment. DISCUS also calculates the flux of once-scattered neutrons that would have been observed if there were no absorption in the sample and if, once scattered, the neutron would emerge without further re-scattering or absorption. Three types of sample geometry are used: an infinite flat plate, a finite flat plate or a finite length cylinder. (The infinite flat plate is included for comparison with other multiple scattering programs.) The program may be used for any sample for which the scattering law is of the form S(/Q/, omega). 2 - Method of solution: Monte Carlo with importance sampling is used. Neutrons are 'forced' both into useful angular trajectories, and useful energy bins. Biasing of the collision point according to the point of entry of the neutron into the sample is also utilised. The first and second order scattered neutron fluxes are calculated in independent histories. For twice-scattered neutron histories a square distribution in Q-omega space is used to sample the neutron coming from the first scattering event, whilst biasing is used for the second scattering event. (A square distribution is used so as to obtain reasonable inelastic-inelastic statistics.) 3 - Restrictions on the complexity of the problem: Unlimited number of detectors. Max. size of (Q, omega) matrix is 39*149. Max. number of points in momentum space for the scattering cross section is 199
Dual scattering foil design for poly-energetic electron beams
International Nuclear Information System (INIS)
Kainz, K K; Antolak, J A; Almond, P R; Bloch, C D; Hogstrom, K R
2005-01-01
The laser wakefield acceleration (LWFA) mechanism can accelerate electrons to energies within the 6-20 MeV range desired for therapy application. However, the energy spectrum of LWFA-generated electrons is broad, on the order of tens of MeV. Using existing laser technology, the therapeutic beam might require a significant energy spread to achieve clinically acceptable dose rates. The purpose of this work was to test the assumption that a scattering foil system designed for a mono-energetic beam would be suitable for a poly-energetic beam with a significant energy spread. Dual scattering foil systems were designed for mono-energetic beams using an existing analytical formalism based on Gaussian multiple-Coulomb scattering theory. The design criterion was to create a flat beam that would be suitable for fields up to 25 x 25 cm 2 at 100 cm from the primary scattering foil. Radial planar fluence profiles for poly-energetic beams with energy spreads ranging from 0.5 MeV to 6.5 MeV were calculated using two methods: (a) analytically by summing beam profiles for a range of mono-energetic beams through the scattering foil system, and (b) by Monte Carlo using the EGS/BEAM code. The analytic calculations facilitated fine adjustments to the foil design, and the Monte Carlo calculations enabled us to verify the results of the analytic calculation and to determine the phase-space characteristics of the broadened beam. Results showed that the flatness of the scattered beam is fairly insensitive to the width of the input energy spectrum. Also, results showed that dose calculated by the analytical and Monte Carlo methods agreed very well in the central portion of the beam. Outside the useable field area, the differences between the analytical and Monte Carlo results were small but significant, possibly due to the small angle approximation. However, these did not affect the conclusion that a scattering foil system designed for a mono-energetic beam will be suitable for a poly