Sample records for scattering signals due

  1. Comparison of collective Thomson scattering signals due to fast ions in ITER scenarios with fusion and auxiliary heating

    DEFF Research Database (Denmark)

    Salewski, Mirko; Asunta, O.; Eriksson, L.-G.


    Auxiliary heating such as neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH) will accelerate ions in ITER up to energies in the MeV range, i.e. energies which are also typical for alpha particles. Fast ions of any of these populations will elevate the collective Thomson...... is chosen such that near perpendicular and near parallel velocity components are resolved. In the investigated ICRH scenario, waves at 50MHz resonate with tritium at the second harmonic off-axis on the low field side. Effects of a minority heating scheme with He-3 are also considered. CTS scattering...... functions for fast deuterons, fast tritons, fast He-3 and the fusion born alphas are presented, revealing that fusion alphas dominate the measurable signal by an order of magnitude or more in the Doppler shift frequency ranges typical for fast ions. Hence the observable CTS signal can mostly be attributed...

  2. Wideband spectrum analysis of ultra-high frequency radio-wave signals due to advanced one-phonon non-collinear anomalous light scattering. (United States)

    Shcherbakov, Alexandre S; Arellanes, Adan Omar


    We present a principally new acousto-optical cell providing an advanced wideband spectrum analysis of ultra-high frequency radio-wave signals. For the first time, we apply a recently developed approach with the tilt angle to a one-phonon non-collinear anomalous light scattering. In contrast to earlier cases, now one can exploit a regime with the fixed optical wavelength for processing a great number of acoustic frequencies simultaneously in the linear regime. The chosen rutile-crystal combines a moderate acoustic velocity with low acoustic attenuation and allows us wide-band data processing within GHz-frequency acoustic waves. We have created and experimentally tested a 6-cm aperture rutile-made acousto-optical cell providing the central frequency 2.0 GHz, frequency bandwidth ∼0.52  GHz with the frequency resolution about 68.3 kHz, and ∼7620 resolvable spots. A similar cell permits designing an advanced ultra-high-frequency arm within a recently developed multi-band radio-wave acousto-optical spectrometer for astrophysical studies. This spectrometer is intended to operate with a few parallel optical arms for processing the multi-frequency data flows within astrophysical observations. Keeping all the instrument's advantages of the previous schematic arrangement, now one can create the highest-frequency arm using the developed rutile-based acousto-optical cell. It permits optimizing the performances inherent in that arm via regulation of both the central frequency and the frequency bandwidth for spectrum analysis.

  3. Decoherence due to elastic rayleigh scattering

    CSIR Research Space (South Africa)

    Uys, H


    Full Text Available for gates in quan- tum computing [1], the generation of spin squeezed states through laser-mediated interactions [2–6], and the trapping and manipulation of neutral atoms in optical lattices [7,8]. These experiments frequently involve superpositions... by [13] Ldu ~�SðtÞ ¼ ��du2 ð�^ ��^þ ~�SðtÞ � 2�^þ ~�SðtÞ�^� þ ~�SðtÞ�^��^þÞ; Lud ~�SðtÞ ¼ ��ud2 ð�^ þ�^� ~�SðtÞ � 2�^� ~�SðtÞ�^þ þ ~�SðtÞ�^þ�^�Þ: �ij is the rate for an ion initially in state jii to scatter a photon and end up in state jji...

  4. Notes on Rayleigh scattering in lidar signals. (United States)

    Adam, Mariana


    Classical and quantum formulations are used to estimate Rayleigh scattering within lidar signals. Within the classical approach, three scenarios are used to characterize atmospheric molecular composition: 2-component atmosphere (N2 and O2), 4-component atmosphere (N2, O2, Ar, and CO2), and 5-component atmosphere (N2, O2, Ar, CO2, and water vapor). First, analysis focuses on Rayleigh scattering, showing the relative difference between the three scenarios within classical approach. The relative difference in molecular scattering between 2(4)-component atmosphere and 5-component atmosphere is below ~1%. The second analysis focuses on the lidar retrieval of aerosol backscatter and extinction coefficients showing the effect of different molecular formulations. A relative difference of ±3% was found between the molecular formulation of 2-component atmosphere and the molecular formulation of 5-component atmosphere. Consideration of the Raman rotational lines blocked by the interference filter is important for the elastic channels, but of little significance in the N2 Raman channel. For lidar retrieval of aerosol profiles, the 5-component approximation is the best when the water vapor profile is known, but 2-component is still adequate and quite accurate when water vapor is only poorly known.

  5. Characteristic energy range of electron scattering due to plasmaspheric hiss (United States)

    Ma, Q.; Li, W.; Thorne, R. M.; Bortnik, J.; Reeves, G. D.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Spence, H. E.; Baker, D. N.; Blake, J. B.; Fennell, J. F.; Claudepierre, S. G.; Angelopoulos, V.


    We investigate the characteristic energy range of electron flux decay due to the interaction with plasmaspheric hiss in the Earth's inner magnetosphere. The Van Allen Probes have measured the energetic electron flux decay profiles in the Earth's outer radiation belt during a quiet period following the geomagnetic storm that occurred on 7 November 2015. The observed energy of significant electron decay increases with decreasing L shell and is well correlated with the energy band corresponding to the first adiabatic invariant μ = 4-200 MeV/G. The electron diffusion coefficients due to hiss scattering are calculated at L = 2-6, and the modeled energy band of effective pitch angle scattering is also well correlated with the constant μ lines and is consistent with the observed energy range of electron decay. Using the previously developed statistical plasmaspheric hiss model during modestly disturbed periods, we perform a 2-D Fokker-Planck simulation of the electron phase space density evolution at L = 3.5 and demonstrate that plasmaspheric hiss causes the significant decay of 100 keV-1 MeV electrons with the largest decay rate occurring at around 340 keV, forming anisotropic pitch angle distributions at lower energies and more flattened distributions at higher energies. Our study provides reasonable estimates of the electron populations that can be most significantly affected by plasmaspheric hiss and the consequent electron decay profiles.

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

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


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

  7. Dynamic Light Scattering Signal Conditioning for Data Processing (United States)

    Rei, Silviu; Chicea, Dan; Ilie, Beriliu; Olaru, Sorin


    When performing data acquisition for a Dynamic Light Scattering experiment, one of the most important aspect is the filtering and conditioning of the electrical signal. The signal is amplified first and then fed as input for the analog digital convertor. As a result a digital time series is obtained. The frequency spectrum is computed by the logical unit offering the basis for further Dynamic Light Scattering analysis methods. This paper presents a simple setup that can accomplish the signal conditioning and conversion to a digital time series.

  8. Digital signal processing based on inverse scattering transform. (United States)

    Turitsyna, Elena G; Turitsyn, Sergei K


    Through numerical modeling, we illustrate the possibility of a new approach to digital signal processing in coherent optical communications based on the application of the so-called inverse scattering transform. Considering without loss of generality a fiber link with normal dispersion and quadrature phase shift keying signal modulation, we demonstrate how an initial information pattern can be recovered (without direct backward propagation) through the calculation of nonlinear spectral data of the received optical signal.

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

    CERN Document Server

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


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

  10. Underwater object classification using scattering transform of sonar signals (United States)

    Saito, Naoki; Weber, David S.


    In this paper, we apply the scattering transform (ST)-a nonlinear map based off of a convolutional neural network (CNN)-to classification of underwater objects using sonar signals. The ST formalizes the observation that the filters learned by a CNN have wavelet-like structure. We achieve effective binary classification both on a real dataset of Unexploded Ordinance (UXOs), as well as synthetically generated examples. We also explore the effects on the waveforms with respect to changes in the object domain (e.g., translation, rotation, and acoustic impedance, etc.), and examine the consequences coming from theoretical results for the scattering transform. We show that the scattering transform is capable of excellent classification on both the synthetic and real problems, thanks to having more quasi-invariance properties that are well-suited to translation and rotation of the object.

  11. Application of Morlet wavelet in the extraction of Brillouin scattering signal envelope (United States)

    Wang, Xin; Huang, Cha-xiang; Zhou, Li


    The Brillouin scattering light signal is a wideband signal containing a lot of phase noises and amplitude noises. And the envelope of the Brillouin scattering signal will include some characteristics due to the influences of temperature and strain change on the sensing fiber. In order to obtain the useful temperature and strain change information, the amplitude demodulation of the noise signal should be conducted, and at the same time, it is necessary to effectively suppress the signal noise. In this paper, Morlet wavelet has been used to do the envelope detection since it has band-pass filtering function and signal demodulation function provided by the orthogonal characteristic between real part and imaginary part. Moreover, the Morlet wavelet function has the characteristic of time-frequency analysis, and it can analyze envelope of the signal and extract characteristic of the signal in the whole frequency range by changing the scale factor and translation factor. Meanwhile, it can also suppress the signal noise effectively. The simulation model has been built to verify the validity of envelope demodulation principle by Morlet wavelet algorithm. Theory analysis and experiment show the algorithm is reasonable and efficient.

  12. Empirical Doppler Characterization of Signals Scattered by Wind Turbines in the UHF Band under Near Field Condition

    Directory of Open Access Journals (Sweden)

    Itziar Angulo


    Full Text Available Time variability of the scattering signals from wind turbines may lead to degradation problems on the communication systems provided in the UHF band, especially under near field condition. In order to analyze the variability due to the rotation of the blades, this paper characterizes empirical Doppler spectra obtained from real samples of signals scattered by wind turbines with rotating blades under near field condition. A new Doppler spectrum model is proposed to fit the spectral characteristics of these signals, providing notable goodness of fit. Finally, the effect of this kind of time variability on the degradation of OFDM signals is studied.

  13. Light-scattering signal may indicate critical time zone to rescue brain tissue after hypoxia (United States)

    Kawauchi, Satoko; Sato, Shunichi; Uozumi, Yoichi; Nawashiro, Hiroshi; Ishihara, Miya; Kikuchi, Makoto


    A light-scattering signal, which is sensitive to cellular/subcellular structural integrity, is a potential indicator of brain tissue viability because metabolic energy is used in part to maintain the structure of cells. We previously observed a unique triphasic scattering change (TSC) at a certain time after oxygen/glucose deprivation for blood-free rat brains; TSC almost coincided with the cerebral adenosine triphosphate (ATP) depletion. We examine whether such TSC can be observed in the presence of blood in vivo, for which transcranial diffuse reflectance measurement is performed for rat brains during hypoxia induced by nitrogen gas inhalation. At a certain time after hypoxia, diffuse reflectance intensity in the near-infrared region changes in three phases, which is shown by spectroscopic analysis to be due to scattering change in the tissue. During hypoxia, rats are reoxygenated at various time points. When the oxygen supply is started before TSC, all rats survive, whereas no rats survive when the oxygen supply is started after TSC. Survival is probabilistic when the oxygen supply is started during TSC, indicating that the period of TSC can be regarded as a critical time zone for rescuing the brain. The results demonstrate that light scattering signal can be an indicator of brain tissue reversibility.

  14. Measurements and simulation of ionospheric scattering on VHF and UHF radar signals: Channel scattering function (United States)

    Rogers, Neil C.; Cannon, Paul S.; Groves, Keith M.


    The design and operation of transionospheric VHF and UHF radars requires knowledge of amplitude and phase scintillation due to ionospheric scattering. Phase coherence is of particular importance where long coherent integration periods and large bandwidths are required. A thin phase screen, parabolic equation based, Trans-Ionospheric Radio Propagation Simulator (TIRPS) is described. Modeled channel scattering functions (CSFs) are compared to experimental VHF and UHF data derived from the Advanced Research Projects Agency Long-range Tracking and Instrumentation Radar on Kwajalein Island (9.4°N, 166.8°E). TIRPS quantitatively reproduces the experimental results, including the quasi-parabolic profile observed in the measured CSFs under strong turbulence conditions. Variations in the simulated CSF with ionospheric phase screen parameters are also presented. Under conditions of high integrated strength of turbulence (CkL), a low phase spectral index (p = 1), indicating relatively dense small-scale irregularities, produces pronounced range spreading. Conversely, when the spectral index is high (p = 4), indicative of strong focusing/defocusing by large-scale irregularities, there is increased Doppler spreading and, when the outer scale of irregularities is large, a greater likelihood of asymmetry of the CSF about the zero Doppler axis.

  15. Dynamic Model of Signal Fading due to Swaying Vegetation

    Directory of Open Access Journals (Sweden)

    Torbjörn Ekman


    Full Text Available In this contribution, we use fading measurements at 2.45, 5.25, 29, and 60 GHz, and wind speed data, to study the dynamic effects of vegetation on propagating radiowaves. A new simulation model for generating signal fading due to a swaying tree has been developed by utilizing a multiple mass-spring system to represent a tree and a turbulent wind model. The model is validated in terms of the cumulative distribution function (CDF, autocorrelation function (ACF, level crossing rate (LCR, and average fade duration (AFD using measurements. The agreements found between the measured and simulated first- and second-order statistics of the received signals through vegetation are satisfactory. In addition, Ricean K-factors for different wind speeds are estimated from measurements. Generally, the new model has similar dynamical and statistical characteristics as those observed in measurements and can thus be used for synthesizing signal fading due to a swaying tree. The synthesized fading can be used for simulating different capacity enhancing techniques such as adaptive coding and modulation and other fade mitigation techniques.

  16. Distortion-induced scattering due to vacancies in NbC/sub 0. 72/

    Energy Technology Data Exchange (ETDEWEB)

    Ohshima, K.; Harada, J.; Morinaga, M.; Georgopoulos, P.; Cohen, J.B.


    The diffuse X-ray (and electron) scattering from NbC/sub 0.72/, previously thought to be due to vacancy octahedra, is shown to be dominated by the scattering due to mean-square atomic displacements with wave vectors near the Brillouin-zone boundary. The atomic displacements are similar to those produced by an optical phonon. On the basis of the sign and amplitude of the displacement parameters a model for the environment around a carbon vacancy is proposed. The Nb nearest neighbors to a vacancy move away from it, whereas the C neighbors move toward it, and this appears to be due to an enhancement of the strength of the Nb-C bond arising from the presence of vacancies on the C sublattice. There is evidence that these vacancies tend to be correlated along 211 vectors.

  17. Influence of Stimuled Raman Scattering on Transmitted Optical Signal in WDM System

    Directory of Open Access Journals (Sweden)

    Ján Ružbarský


    Full Text Available Paper is focused on simulations behavior of signals in high-speed networks. Huge amount of transmitted information and increase in transmission speed create unwanted events in optical fiber. The main influences comprise effects such as: stimulated Raman scattering and stimulated Brillouin scattering. This paper is focused only on Raman scattering. For transmitting a signal through optical fiber one needs to select an appropriate wavelength. This is one of goals the experiment in this article. Signals were transmitted accordance with Dense Wavelength Division Multiplexing (DWDM and spacing among channels 100GHz.

  18. Experimental Determination of Dual-Wavelength Mie Lidar Geometric form Factor Combining Side-Scatter and Back-Scatter Signals

    Directory of Open Access Journals (Sweden)

    Wang Zhenzhu


    Full Text Available In theory, lidar overlap factor can be derived from the difference between the particle backscatter coefficient retrieved from lidar elastic signal without overlap correction and the actual particle backscatter coefficient, which can be obtained by other measured techniques. The side-scatter signal using a CCD camera is testified to be a powerful tool to detect the particle backscatter coefficient in near ground layer during night time. In experiment, by combining side-scatter and backscatter signals the geometric form factor for vertically-pointing Mie lidar in 532 nm channel is determined successfully, which is corrected by an iteration algorithm combining the retrieved particle backscatter coefficient using CCD sidescatter method and Fernald method. In this study, the method will be expanded to 1064 nm channel in dual-wavelength Mie lidar during routine campaigns. The experimental results in different atmosphere conditions demonstrated that the method present in this study is available in practice.

  19. Joint Time-Frequency Signal Processing Scheme in Forward Scattering Radar with a Rotational Transmitter

    Directory of Open Access Journals (Sweden)

    Raja Syamsul Azmir Raja Abdullah


    Full Text Available This paper explores the concept of a Forward Scattering Radar (FSR system with a rotational transmitter for target detection and localization. Most of the research and development in FSR used a fixed dedicated transmitter; therefore, the detection of stationary and slow moving target is very difficult. By rotating the transmitter, the received signals at the receiver contain extra information carried by the Doppler due to the relative movement of the transmitter-target-receiver. Hence, rotating the transmitter enhances the detection capability especially for a stationary and slow-moving target. In addition, it increases the flexibility of the transmitter to control the signal direction, which broadens the coverage of FSR networks. In this paper, a novel signal processing for the new mode of FSR system based on the signal’s joint time-frequency is proposed and discussed. Additionally, the concept of the FSR system with the rotational transmitter is analyzed experimentally for the detection and localization of a stationary target, at very low speed and a low profile target crossing the FSR baseline. The system acts as a virtual fencing of a remote sensor for area monitoring. The experimental results show that the proposed mode with the new signal processing scheme can detect a human intruder. The potential applications for this system could be used for security and border surveillance, debris detection on an airport runway, ground aerial monitoring, intruder detection, etc.

  20. Near-end solution for lidar signals that includes a multiple-scattering component. (United States)

    Kovalev, Vladimir A


    A variant of the near-end solution is presented that allows one to consider a multiple-scattering component in lidar measurements of distant clouds or dense smoke. It is assumed that the lidar signal, contaminated by multiple scattering, obeys a single-scattering lidar equation in which an additional term, which is related to the range-dependent ratio of a multiple-to-single-scattering component, is included. For the inversion, a brink solution is proposed that does not require an a priori selection of the extinction-to-backscatter ratio in the optically dense aerosol formation under investigation. The solution requires either knowledge of the multiple-to-single-scattering ratio (e.g., determined experimentally with a multiangle lidar) or the use of the analytical dependence of the multiple-to-single-scattering ratio on the aerosol optical depth. In the latter case, an iterative technique is used.

  1. Blackening of unprotected dental X-ray films due to scattered radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sewerin, I.; Stoltze, K.


    Unexposed films awaiting exposure as well as exposed films awaiting processing are subjected to scattered radiation if kept unprotected in the dental X-ray clinic. The purpose of the present study was to analyze the influence of various storing principles, film speed, and distance from X-ray source upon the degree of film blackening. Test films were subjected to scattered radiation from 150 exposures. Maximum additional blackening (0.27 D) was recorded for type E films not protected by lead foil at the shortest distance studied (55 cm). At a distance of 200 cm blackening was reduced to 0.02 D and could be further reduced by utilizing the inherent protective effect of the lead foil. It is concluded that if dental X-ray films not in use are kept a distance of 200 cm from the X-ray source and protected by lead foil additional blackening due to scattered radiation is negligible and further protective precautions are unnecessary.

  2. Surface light scattering: integrated technology and signal processing

    DEFF Research Database (Denmark)

    Lading, L.; Dam-Hansen, C.; Rasmussen, E.


    systems representing increasing levels of integration are considered. It is demonstrated that efficient signal and data processing can be achieved by evaluation of the statistics of the derivative of the instantaneous phase of the detector signal. (C) 1997 Optical Society of America....

  3. VLF signal anomalies dues to TS and Hurricanes (United States)

    Nait Amor, Samir


    VLF signal propagates by multiples reflection in the Earth-Ionosphere wave guide. It constitutes a powerful tool to study the lower region of the ionosphere, the D region. This technique was applied to study perturbations related to the solar flares effect, TGF, the connection between TLEs and Early events.... In this contribution I will present a new results on the evidence of signal perturbations associated with TS and Hurricanes. A wavelet spectral analysis is applied to the signal amplitude to search for eventual Atmospheric Gravity wave which may be the origin of the signal perturbations.

  4. Nonuniqueness of the Phase Shift in Central Scattering due to Monodromy

    NARCIS (Netherlands)

    Dullin, Holger R.; Waalkens, Holger


    Scattering at a central potential is completely characterized by the phase shifts which are the differences in phase between outgoing scattered and unscattered partial waves. In this Letter, it is shown that, for 2D scattering at a repulsive central potential, the phase shift cannot be uniquely

  5. Suppressing interfering scattered signals in swept-frequency radar measurements by using frequency domain Wiener filtering (United States)

    Weissman, David E.; Staton, Leo D.


    A novel approach to the reduction of scattered, interfering signals that corrupt measurements of the signal backscattered from radar targets of interest is being developed. It is being explored with sphere measurements in an indoor microwave radar range. This method is based on the concept of Wiener filtering (which minimizes the difference between the signal plus noise and the desired signal in the time domain). In contrast to the traditional Wiener filter, in which the time domain error between two sequences are minimized, the approach reported uses the frequency domain phasor amplitudes of a swept frequency signal. It minimizes the difference (least-mean-square-magnitude) between the signal-plus-noise and the signal complex phasors, across the entire spectrum.

  6. Optimized signal-to-noise ratio with shot noise limited detection in Stimulated Raman Scattering microscopy

    NARCIS (Netherlands)

    Moester, M.J.B.; Ariese, F.; de Boer, J.F.


    We describe our set-up for Stimulated Raman Scattering (SRS) microscopy with shot noise limited detection for a broad window of biologically relevant laser powers. This set-up is used to demonstrate that the highest signal-to-noise ratio (SNR) in SRS with shot noise limited detection is achieved

  7. Polarization of Sunyaev-Zel'dovich signal due to electron pressure anisotropy in galaxy clusters (United States)

    Khabibullin, I.; Komarov, S.; Churazov, E.; Schekochihin, A.


    We describe polarization of the Sunyaev-Zel'dovich (SZ) effect associated with electron pressure anisotropy likely present in the intracluster medium (ICM). The ICM is an astrophysical example of a weakly collisional plasma where the Larmor frequencies of charged particles greatly exceed their collision frequencies. This permits formation of pressure anisotropies, driven by evolving magnetic fields via adiabatic invariance, or by heat fluxes. SZ polarization arises in the process of Compton scattering of the cosmic microwave background (CMB) photons off the thermal ICM electrons due to the difference in the characteristic thermal velocities of the electrons along two mutually orthogonal directions in the sky plane. The signal scales linearly with the optical depth of the region containing large-scale correlated anisotropy, and with the degree of anisotropy itself. It has the same spectral dependence as the polarization induced by cluster motion with respect to the CMB frame (kinematic SZ effect polarization), but can be distinguished by its spatial pattern. For the illustrative case of a galaxy cluster with a cold front, where electron transport is mediated by Coulomb collisions, we estimate the CMB polarization degree at the level of 10-8 (˜10 nK). An increase of the effective electron collisionality due to plasma instabilities will reduce the effect. Such polarization, therefore, may be an independent probe of the electron collisionality in the ICM, which is one of the key properties of a high-β weakly collisional plasma from the point of view of both astrophysics and plasma theory.

  8. Measurement of Rank and Other Properties of Direct and Scattered Signals

    Directory of Open Access Journals (Sweden)

    Svante Björklund


    Full Text Available We have designed an experiment for low-cost indoor measurements of rank and other properties of direct and scattered signals with radar interference suppression in mind. The signal rank is important also in many other applications, for example, DOA (Direction of Arrival estimation, estimation of the number of and location of transmitters in electronic warfare, and increasing the capacity in wireless communications. In real radar applications, such measurements can be very expensive, for example, involving airborne radars with array antennas. We have performed the measurements in an anechoic chamber with several transmitters, a receiving array antenna, and a moving reflector. Our experiment takes several aspects into account: transmitted signals with different correlation, decorrelation of the signals during the acquisition interval, covariance matrix estimation, noise eigenvalue spread, calibration, near-field compensation, scattering in a rough surface, and good control of the influencing factors. With our measurements we have observed rank, DOA spectrum, and eigenpatterns of direct and scattered signals. The agreement of our measured properties with theoretic and simulated results in the literature shows that our experiment is realistic and sound. The detailed description of our experiment could serve as help for conducting other well-controlled experiments.

  9. DOA estimation for local scattered CDMA signals by particle swarm optimization. (United States)

    Chang, Jhih-Chung


    This paper deals with the direction-of-arrival (DOA) estimation of local scattered code-division multiple access (CDMA) signals based on a particle swarm optimization (PSO) search. For conventional spectral searching estimators with local scattering, the searching complexity and estimating accuracy strictly depend on the number of search grids used during the search. In order to obtain high-resolution and accurate DOA estimation, a smaller grid size is needed. This is time consuming and it is unclear how to determine the required number of search grids. In this paper, a modified PSO is presented to reduce the required search grids for the conventional spectral searching estimator with the effects of local scattering. Finally, several computer simulations are provided for illustration and comparison.

  10. The No-Higgs Signal: Strong WW Scattering at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Michael S. Chanowitz


    Strong WW scattering at the LHC is discussed as a manifestation of electroweak symmetry breaking in the absence of a light Higgs bosom. The general framework of the Higgs mechanism--with or without a Higgs boson--is reviewed, and unitarity is shown to fix the scale of strong WW scattering. Strong WW scattering is also shown to be a possible outcome of five-dimensional models, which do not employ the usual Higgs mechanism at the TeV scale. Precision electroweak constraints are briefly discussed. Illustrative LHC signals are reviewed for models with QCD-like dynamics, stressing the complementarity of the W{sup {+-}}Z and like-charge W{sup +}W{sup +} + W{sup -}W{sup -} channels.

  11. Electron scattering due to dislocation wall strain field in GaN layers


    Krasavin, S. E.


    The effect of edge-type dislocation wall strain field on the Hall mobility in n-type epitaxial GaN was theoretically investigated through deformation potential within the relaxation time approach. It was found that this channel of scattering can play a considerable role in the low-temperature transport at the certain set of the model parameters. The low temperature experimental data were fitted by including this mechanism of scattering along with ionized impurities and charge dislocation ones.

  12. On the calculation of x-ray scattering signals from pairwise radial distribution functions

    DEFF Research Database (Denmark)

    Dohn, Asmus Ougaard; Biasin, Elisa; Haldrup, Kristoffer


    We derive a formulation for evaluating (time-resolved) x-ray scattering signals of solvated chemical systems, based on pairwise radial distribution functions, with the aim of this formulation to accompany molecular dynamics simulations. The derivation is described in detail to eliminate any...... possible ambiguities, and the result includes a modification to the atom-type formulation which to our knowledge is previously unaccounted for. The formulation is numerically implemented and validated....

  13. Numerical characterisation of guided wave scattering due to welds in rails

    CSIR Research Space (South Africa)

    Long, CS


    Full Text Available such analyses. This paper employs a hybrid SAFE-3D method to investigate the scattering of guided waves interacting with discontinuities, such as welds, in continuous welded train rails. The aim of the analysis is to predict transmission and reflection...

  14. Collective Thomson scattering measurements of fast-ion transport due to sawtooth crashes in ASDEX Upgrade

    DEFF Research Database (Denmark)

    Rasmussen, Jesper; Nielsen, Stefan Kragh; Pedersen, Morten Stejner


    . Here we present the first collective Thomson scattering (CTS) measurements of sawtooth-induced redistribution of fast ions at ASDEX Upgrade. These also represent the first localized fast-ion measurements on the high-field side of this device. The results indicate fast-ion losses in the phase...

  15. Estimation of Effective Transmission Loss Due to Subtropical Hydrometeor Scatters using a 3D Rain Cell Model for Centimeter and Millimeter Wave Applications (United States)

    Ojo, J. S.; Owolawi, P. A.


    The problem of hydrometeor scattering on microwave radio communication down links continues to be of interest as the number of the ground and earth space terminals continually grows The interference resulting from the hydrometeor scattering usually leads to the reduction in the signal-to-noise ratio ( SNR) at the affected terminal and at worst can even end up in total link outage. In this paper, an attempt has been made to compute the effective transmission loss due to subtropical hydrometeors on vertically polarized signals in Earth-satellite propagation paths in the Ku, Ka and V band frequencies based on the modified Capsoni 3D rain cell model. The 3D rain cell model has been adopted and modified using the subtropical log-normal distributions of raindrop sizes and introducing the equivalent path length through rain in the estimation of the attenuation instead of the usual specific attenuation in order to account for the attenuation of both wanted and unwanted paths to the receiver. The co-channels, interference at the same frequency is very prone to the higher amount of unwanted signal at the elevation considered. The importance of joint transmission is also considered.

  16. Solar Wind Strahl Observations and Their Implication to the Core-Halo Formation due to Scattering (United States)

    Vinas, Adolfo F.


    A study of the kinetic properties of the strahl electron velocity distribution functions (VDF?s) in the solar wind is presented. This study focuses on the mechanisms that control and regulate the electron VDF?s and the stability of the strahl electrons in the solar wind; mechanisms that are not yet well understood. Various parameters are investigated such as the strahl-electron density, temperature anisotropy, and electron heat-flux. These parameters are used to investigate the stability of the strahl population. The analysis check for whether the strahl electrons are constrained by some instability (e.g., the whistler or KAW instabilities), or are maintained by other types of processes. The electron heat-flux and temperature anisotropy are determined by modeling of the 3D-VDF?s from which the moments properties of the various populations are obtained. The results of this study have profound implication on the current hypothesis about the probable formation of the solar wind halo electrons produced from the scattering of the strahl population. This hypothesis is strengthened by direct observations of the strahl electrons being scattered into the core-halo in an isolated event. The observation implies that the scattering of the strahl is not a continuous process but occurs in bursts in regions where conditions for wave growth providing the scattering are optimum. Sometimes, observations indicate that the strahl component is anisotropic (Tper/Tpal approx. 2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism, however this condition is not always observed. The study is based on high time resolution data from the Cluster/PEACE electron spectrometer.

  17. Influence of Spectral Transfer Processes in Compressible Low Frequency Plasma Turbulence on Scattering and Refraction of Electromagnetic Signals (United States)



  18. Efficient Raw Signal Generation Based on Equivalent Scatterer and Subaperture Processing for SAR with Arbitrary Motion

    Directory of Open Access Journals (Sweden)

    H.T. Xie


    Full Text Available An efficient SAR raw signal generation method based on equivalent scatterer and subaperture processing is proposed in this paper. It considers the radar’s motion track, which can obtain the precise raw signal for the real SAR. First, the imaging geometry with arbitrary motion is established, and then the scene is divided into several equidistant rings. Based on the equivalent scatterer model, the approximate expression of the SAR system transfer function is derived, thus each pulse’s raw signal can be generated by the convolution of the transmitted signal and system transfer function, performed by the fast Fourier transform (FFT. To further improve the simulation efficiency, the subaperture and polar subscene processing is used. The system transfer function of pluses for the same subaperture is calculated simultaneously by the weighted sum of all subscenes’ equivalent backscattering coefficient in the same equidistant ring, performed by the nonuniform FFT (NUFFT. The method only involves the FFT, NUFFT and complex multiplication operations, which means the easier implementation and higher efficiency. Simulation results are given to prove the validity of this method.

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

    Bismarck, Jonas von; Fischer, Jürgen


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

  20. Determination of nanograms of proteins based on the amplified resonance light scattering signals of Tichromine (United States)

    Cai, Changqun; Chen, Xiaoming


    A new high-sensitivity detection of protein assay at the nanogram level is developed based on the amplified resonance light scattering signals (RLS) of Tichromine (TCM). In Walpole (NaAc-HCl) buffer (pH 4.05), TCM reacts with proteins to form large particles, which results in remarkable enhanced RLS signals characterized by three peaks at 293 nm, 399 nm and 553 nm. Mechanistic studies showed that the enhanced RLS stems from a large complex of TCM-BSA formed for the electrostatic effect between TCM and BSA. With the enhanced RLS signals at the three wavelengths, the enhanced RLS intensity is proportional to the concentration of proteins in an appropriate range. The lowest limit of determination was 7.4 ng mL -1. The proposed method was successfully applied to determine total protein in human serum samples.

  1. Two-magnon scattering in permalloy thin films due to rippled substrates (United States)

    Körner, M.; Lenz, K.; Gallardo, R. A.; Fritzsche, M.; Mücklich, A.; Facsko, S.; Lindner, J.; Landeros, P.; Fassbender, J.


    We report on the influence of correlated substrate roughness on the two-magnon scattering in 30 nm Ni81Fe19 thin films. Using ion beam erosion, periodically modulated substrates (ripple) were produced with wavelengths between 20 and 432nm. This surface corrugation is adopted by magnetic layers grown on top yielding dipolar stray fields if magnetization and ripple ridges are aligned perpendicular to each other. In case of λ≥222nm, the evolving periodic field pattern triggers two-magnon scattering, which depends strongly on the direction of magnetization with respect to the ripple pattern. In-plane broadband ferromagnetic resonance reveals prominent peaks in the frequency-dependent linewidth measured perpendicularly to the ripple ridges. These peaks can be switched off if the magnetization is aligned along the ripple ridges. Our results are compared to predictions obtained from recent theory on spin waves in periodically perturbed films.

  2. Anomalously Hot Electrons due to Rescatter of Stimulated Raman Scattering in the Kinetic Regime

    CERN Document Server

    Winjum, B J; Tsung, F S; Mori, W B


    Using particle-in-cell simulations, we examine hot electron generation from electron plasma waves excited by stimulated Raman scattering and rescattering in the kinetic regime where the wavenumber times the Debye length (k\\lambda_D) is greater than 0.3 for backscatter. We find that for laser and plasma conditions of possible relevance to experiments at the National Ignition Facility (NIF), anomalously energetic electrons can be produced through the interaction of a discrete spectrum of plasma waves generated from SRS (back and forward scatter), rescatter, and the Langmuir decay of the rescatter-generated plasma waves. Electrons are bootstrapped in energy as they propagate into plasma waves with progressively higher phase velocities.

  3. Influence of low concentrations of scatterers and signal detection time on the results of their measurements using dynamic light scattering (United States)

    Bunkin, N. F.; Shkirin, A. V.; Suyazov, N. V.; Chaikov, L. L.; Chirikov, S. N.; Kirichenko, M. N.; Nikiforov, S. D.; Tymper, S. I.


    The influence of limited detection time on the form of the autocorrelation function (ACF) has been analysed for measurements in low-concentration suspensions by dynamic light scattering with allowance for the spatial distribution of the laser beam intensity. The general view of the ACF of the scattered light intensity is obtained for a Gaussian beam and a finite measurement time. The results of the theoretical analysis are compared with the experimental data and the results obtained by computer simulation of the scattering from an ensemble of particles involved in Brownian motion in a Gaussian beam. It is shown that, in the case of low suspension concentrations, the ACF distortions related to finite detection time lead to underestimation of the particle sizes and occurrence of an artefact peak in the distribution of the scattered light intensity over scatterer sizes. An empirical dependence of the measured size of particles on their number in the scattering volume is found.

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

    Directory of Open Access Journals (Sweden)

    P. J. S. Williams

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

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

    Directory of Open Access Journals (Sweden)

    P. J. S. Williams


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

  6. Enhancement of Raman scattering signal of a few molecules using photonic nanojet mediated SERS technique

    Energy Technology Data Exchange (ETDEWEB)

    Das, G. M.; Parit, M. K.; Laha, R.; Dantham, V. R., E-mail: [Department of Physics, Indian Institute of Technology Patna, Bihta, Bihar, India 801103 (India)


    Now a days, single molecule surface enhanced Raman spectroscopy (SMSERS) has become a fascinating tool for studying the structural properties, static and dynamic events of single molecules (instead of ensemble average), with the help of efficient plasmonic nanostructures. This is extremely useful in the field of proteomics because the structural properties of protein molecules are heterogeneous. Even though, SMSERS provides wealthy information about single molecules, it demands high quality surface enhanced Raman scattering (SERS) substrates. So far, a very few researchers succeeded in demonstrating the single molecule Raman scattering using conventional SERS technique. However, the experimental S/N of the Raman signal has been found to be very poor. Recently, with the help of photonic nanojet of an optical microsphere, we were able to enhance the SERS signal of a few molecules adsorbed on the SERS substrates (gold symmetric and asymmetric nanodimers and trimers dispersed on a glass slide). Herein, we report a few details about photonic nanojet mediated SERS technique, a few experimental results and a detailed theoretical study on symmetric and asymmetric nanosphere dimers to understand the dependence of localised surface plasmon resonance (LSPR) wavelength of a nanodimer on the nanogap size and polarization of the excitation light.

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

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


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

  8. Exponential increase of signal crayfish in running waters in Sweden – due to illegal introductions?

    Directory of Open Access Journals (Sweden)

    Bohman P.


    Full Text Available Sweden has only one indigenous species of crayfish, the noble crayfish (Astacus astacus, Fabricius. There has been a steady decline of noble crayfish populations in Sweden since 1907, mainly due to the crayfish plague. To substitute the noble crayfish fishery lost, the Swedish government launched a large-scale introduction of the signal crayfish (Pacifastacus leniusculus Dana. Today, the signal crayfish is regarded as a chronic carrier of the crayfish plague, and an expansion of the species may seriously threaten the noble crayfish. This paper examines the decrease of noble crayfish populations, and the concurrent expansion of signal crayfish in running waters. Data from the Swedish Electrofishing RegiSter (SERS was used. We found that in 1980–1984 the noble crayfish occurred in 4.5% of the studied river sections. In 2008–2009 the occurrences had decreased to 1.9%. In contrast, the signal crayfish had increased in occurrence, from 0.2% (1980–1984 to 11.8% in (2008–2009. We studied the number of stocking permits for signal crayfish introductions, and the available signal crayfish population from the open fishery in Lake Vättern, as possible causes of this expansion. A negative correlation between stocking permits and increased occurrence in streams, and a positive correlation between the availability of crayfish in Lake Vättern and the occurrence in streams was found. This suggests that the expansion of signal crayfish may be due to illegal introductions, further endangering the endemic noble crayfish.

  9. Amplification of Surface-Enhanced Raman Scattering Due to Substrate-Mediated Localized Surface Plasmons in Gold Nanodimers

    KAUST Repository

    Yue, Weisheng


    Surface-enhanced Raman scattering (SERS) is ubiquitous in chemical and biochemical sensing, imaging and identification. Maximizing SERS enhancement is a continuous effort focused on the design of appropriate SERS substrates. Here we show that significant improvement in a SERS signal can be achieved with substrates combining localized surface plasmon resonances and a nonresonant plasmonic substrate. By introducing a continuous gold (Au) film underneath Au nanodimers antenna arrays, an over 10-fold increase in SERS enhancement is demonstrated. Triangular, rectangle and disc dimers were studied, with bowtie antenna providing highest SERS enhancement. Simulations of electromagnetic field distributions of the Au nanodimers on the Au film support the observed enhancement dependences. The hybridization of localized plasmonic modes with the image modes in a metal film provides a straightforward way to improve SERS enhancement in designer SERS substrate.

  10. Measurement of the sound velocity in fluids using the echo signals from scattering particles. (United States)

    Lenz, Michael; Bock, Martin; Kühnicke, Elfgard; Pal, Josef; Cramer, Andreas


    With conventional methods the sound velocity c in fluids can be determined using the back wall echo. This paper proposes a novel technique, in which the signals reflected by scattering particles suspended in a fluid are analysed instead. The basic idea is that the particles generate the strongest echo signal when being located in the sound field maximum. Therefore the position of the echo signal maximum is a measure for the propagation time to the sound field maximum. Provided that calibration data or sound field simulations for the ultrasonic transducer are available, this propagation time suffices to determine both sound velocity and the location of the sound field maximum. The feasibility of the new approach is demonstrated by different kinds of experiments: (i) Measurements of the sound velocity c in four fluids covering the wide range between 1116 and 2740m/s. The results show good agreement with values published elsewhere. (ii) Using the dependence of the sound velocity on temperature, it is possible to vary c over the comparatively small range between 1431 and 1555m/s with increments of less than 10m/s. The measured statistical variation of 1.4m/s corresponds to a relative uncertainty not worse than 0.1%. (iii) The focus position, i.e. the distance of the maximum of the sound field from the transducer, was varied by time-shifted superposition of the receive signals belonging to the different elements of an annular array. The results indicate that the novel method is even capable of measuring profiles of the sound velocity along the ultrasonic beam non-invasively. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Electron density increases due to Lightning activity as deduced from LWPC code and VLF signal perturbations. (United States)

    Samir, Nait Amor; Bouderba, Yasmina

    VLF signal perturbations in association with thunderstorm activity appear as changes in the signal amplitude and phase. Several papers reported on the characteristics of thus perturbations and their connection to the lightning strokes amplitude and polarity. In this contribution, we quantified the electrons density increases due to lightning activity by the use of the LWPC code and VLF signal perturbations parameters. The method is similar to what people did in studying the solar eruptions effect. the results showed that the reference height (h') decreased to lower altitudes (between 70 and 80 km). From the LWPC code results the maximum of the electron density was then deduced. Therefore, a numerical simulation of the atmospheric species times dependences was performed to study the recovery times of the electrons density at different heights. The results showed that the recovery time last for several minutes and explain the observation of long recovery Early signal perturbations.

  12. Spectral Dependent Degradation of the Solar Diffuser on Suomi-NPP VIIRS Due to Surface Roughness-Induced Rayleigh Scattering

    Directory of Open Access Journals (Sweden)

    Xi Shao


    Full Text Available The Visible Infrared Imaging Radiometer Suite (VIIRS onboard Suomi National Polar Orbiting Partnership (SNPP uses a solar diffuser (SD as its radiometric calibrator for the reflective solar band calibration. The SD is made of Spectralon™ (one type of fluoropolymer and was chosen because of its controlled reflectance in the Visible/Near-Infrared/Shortwave-Infrared region and its near-Lambertian reflectance property. On-orbit changes in VIIRS SD reflectance as monitored by the Solar Diffuser Stability Monitor showed faster degradation of SD reflectance for 0.4 to 0.6 µm channels than the longer wavelength channels. Analysis of VIIRS SD reflectance data show that the spectral dependent degradation of SD reflectance in short wavelength can be explained with a SD Surface Roughness (length scale << wavelength based Rayleigh Scattering (SRRS model due to exposure to solar UV radiation and energetic particles. The characteristic length parameter of the SD surface roughness is derived from the long term reflectance data of the VIIRS SD and it changes at approximately the tens of nanometers level over the operational period of VIIRS. This estimated roughness length scale is consistent with the experimental result from radiation exposure of a fluoropolymer sample and validates the applicability of the Rayleigh scattering-based model. The model is also applicable to explaining the spectral dependent degradation of the SDs on other satellites. This novel approach allows us to better understand the physical processes of the SD degradation, and is complementary to previous mathematics based models.

  13. Optimized Signal-To Ratio with Shot Noise Limited Detection in Stimulated Raman Scattering Microscopy (United States)

    Moester, M. J. B.; Ariese, F.; de Boer, J. F.


    We describe our set-up for Stimulated Raman Scattering (SRS) microscopy with shot noise limited detection for a broad window of biologically relevant laser powers. This set-up is used to demonstrate that the highest signal-to-noise ratio (SNR) in SRS with shot noise limited detection is achieved with a time-averaged laser power ratio of 1:2 of the unmodulated and modulated beam. In SRS, two different coloured laser beams are incident on a sample. If the energy difference between them matches a molecular vibration of a molecule, energy can be transferred from one beam to the other. By applying amplitude modulation to one of the beams, the modulation transfer to the other beam can be measured. The efficiency of this process is a direct measure for the number of molecules of interest in the focal volume. Combined with laser scanning microscopy, this technique allows for fast and sensitive imaging with sub-micrometre resolution. Recent technological advances have resulted in an improvement of the sensitivity of SRS applications, but few show shot noise limited detection. The dominant noise source in this SRS microscope is the shot noise of the unmodulated, detected beam. Under the assumption that photodamage is linear with the total laser power, the optimal SNR shifts away from equal beam powers, where the most signal is generated, to a 1:2 power ratio. Under these conditions the SNR is maximized and the total laser power that could induce photodamage is minimized. Compared to using a 1:1 laser power ratio, we show improved image quality and a signal-to-noise ratio improvement of 8 % in polystyrene beads and C. Elegans worms. Including a non-linear damage mechanism in the analysis, we find that the optimal power ratio converges to a 1:1 ratio with increasing order of the non-linear damage mechanism.

  14. Multifunctional microwave photonic signal processor based on dual-parallel Mach-Zehnder modulator and stimulated Brillouin scattering (United States)

    Shi, Zhan; Wang, Ling; Yang, Cheng Wu; Li, Ming; Zhu, Ning Hua; Li, Wei


    We report a multifunctional microwave photonic signal processor based on dual-parallel Mach-Zehnder modulator and stimulated Brillouin scattering. The signal processor acts as a microwave photonic filter (MPF) and microwave photonic phase shifter (MPS) simultaneously. The MPF and MPS can be tuned separately. Experimental results demonstrate that the central frequency of the bandpass MPF is tunable from 3 to 18 GHz while the MPS in the passband of the MPF is continuously adjustable over 360 deg.

  15. Ordinary mode reflectometry. Modification of the scattering and cut-off responses due to the shape of localized density fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Fanack, C.; Boucher, I.; Heuraux, S.; Leclert, G. [Centre National de la Recherche Scientifique (CNRS), 54 - Nancy (France). Lab. de Physique du Solide; Clairet, F.; Zou, X.L. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee


    Ordinary wave reflectometry in a plasma containing a localized density perturbation is studied with a 1-D model. The phase response is studied as a function of the wavenumber and position of the perturbation. It is shown that it strongly depends upon the perturbation shape and size. For a small perturbation wavenumber, the response is due to the oscillation of the cut-off layer. For larger wavenumbers, two regimes are found: for a broad perturbation, the phase response is an image of the perturbation itself; for a narrow perturbation, it is rather an image of the Fourier transform. For tokamak plasmas it turns out that, for the fluctuation spectra usually observed, the phase response comes primarily from those fluctuations that are localized at the cut-off. Results of a 2-D numerical model show that geometry effects are negligible for the scattering by radial fluctuations. (author). 18 refs.

  16. Absent Vascular Signal on Time-of-Flight Magnetic Resonance Angiography Due to Recent Ferumoxytol Infusion. (United States)

    Singhal, Aparna; Curé, Joel K

    Time-of-flight magnetic resonance angiography is used for craniocervical arterial evaluation. Absent flow-related signal may be the result of slow flow, complex flow, or focal susceptibility effects. We report a case with complete absence of flow-related signal in the intracranial and cervical vessels due to ferumoxytol infusion given 5 days before magnetic resonance angiography. Ferumoxytol is a newly approved parenteral therapy for iron-deficiency anemia in patients with renal failure and awareness of this drug-magnetic resonance imaging interaction is needed.

  17. Signal enhancement of surface enhanced Raman scattering and surface enhanced resonance Raman scattering using in situ colloidal synthesis in microfluidics. (United States)

    Wilson, Rab; Bowden, Stephen A; Parnell, John; Cooper, Jonathan M


    We demonstrate the enhanced analytical sensitivity of both surface enhanced Raman scattering (SERS) and surface enhanced resonance Raman scattering (SERRS) responses, resulting from the in situ synthesis of silver colloid in a microfluidic flow structure, where both mixing and optical interrogation were integrated on-chip. The chip-based sensor was characterized with a model Raman active label, rhodamine-6G (R6G), and had a limit of detection (LOD) of ca. 50 fM (equivalent to single molecule detection). The device was also used for the determination of the natural pigment, scytonemin, from cyanobacteria (as an analogue for extraterrestrial life existing in extreme environments). The observed LOD of approximately 10 pM (ca. <400 molecules) demonstrated the analytical advantages of working with freshly synthesized colloid in such a flow system. In both cases, sensitivities were between 1 and 2 orders of magnitude greater in the microfluidic system than those measured using the same experimental parameters, with colloid synthesized off-chip, under quiescent conditions.

  18. Conversion of phase-modulated signals to amplitude-modulated signals in SOAs due to mirror reflections

    DEFF Research Database (Denmark)

    Blaaberg, Søren; Mørk, Jesper


    We present theoretical results that show conversion of phase modulated signals to amplitude modulated signals in an SOA. Large-signal and small-signal calculations show significant conversion responses caused by even minute reflections at the end mirrors.......We present theoretical results that show conversion of phase modulated signals to amplitude modulated signals in an SOA. Large-signal and small-signal calculations show significant conversion responses caused by even minute reflections at the end mirrors....

  19. SU-E-I-55: The Contribution to Skin Dose Due to Scatter From the Patient Table and the Head Holder During Fluoroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Islam, N; Xiong, Z; Vijayan, S; Rudin, S; Bednarek, D [Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY (United States)


    Purpose: To determine contributions to skin dose due to scatter from the table and head holder used during fluoroscopy, and also to explore alternative design material to reduce the scatter dose. Methods: Measurements were made of the primary and scatter components of the xray beam exiting the patient table and a cylindrical head holder used on a Toshiba Infinix c-arm unit as a function of kVp for the various beam filters on the machine and for various field sizes. The primary component of the beam was measured in air with the object placed close to the x-ray tube with an air gap between it and a 6 cc parallel-plate ionization chamber and with the beam collimated to a size just larger than the chamber. The primary plus scatter radiation components were measured with the object moved to a position in the beam next to the chamber for larger field sizes. Both sets of measurements were preformed while keeping the source-to-chamber distance fixed. The scatter fraction was estimated by taking the ratio of the difference between the two measurements and the reading that included both primary and scatter. Similar measurements were also made for a 2.3 cm thick Styrofoam block which could substitute for the patient support. Results: The measured scatter fractions indicate that the patient table as well as the head holder contributes an additional 10–16% to the patient entrance dose depending on field size. Forward scatter was reduced with the Styrofoam block so that the scatter fraction was about 4–5%. Conclusion: The results of this investigation demonstrated that scatter from the table and head holder used in clinical fluoroscopy contribute substantially to the skin dose. The lower contribution of scatter from Styrofoam suggests that there is an opportunity to redesign patient support accessories to reduce the skin dose. Partial support from NIH grant R01EB002873 and Toshiba Medical Systems Corporation Equipment Grant.

  20. Study of the early signal perturbations due to GJ and Elves using the LWPC code (United States)

    Nait Amor, Samir; Ghalila, Hassen; Bouderba, Yasmina


    Early events are a Very Low Frequencies (VLF) signal perturbations recorded during a lightning activity. The properties of these signal perturbations and their association to the lightning peak current and/or Transient Luminous Events (TLEs) were widely studied. In a recently analysis a new early signal perturbations whose recovery time persists for several minutes were discovered. The underlying cause of these events is still unclear. In a recently published work, these events were attributed to the lightning peak current and the type of associated TLE. In others, and newly published papers, analyzes were done where all kind of early events were considered. Statistical results showed that the occurrence of long recovery events is independent of the lightning current amplitude and/or TLEs type. To understand which is the main cause of these events, we analyzed two types of early signal perturbations: One was a typical event (~200s time duration) in association with a Gigantic Jet and the second was a long recovery event in association with an elve recorded on December 12 2009 during the EuroSprite campaign. In addition to the VLF signal analysis, we used the Long Wave Propagation Capability (LWPC) code to simulate the unperturbed and perturbed signal parameters (amplitude and phase), to determine the signal modes attenuation coefficient and then to infer the electron density increases in the disturbed region. The results showed that the reference height was reduced from its ambient value (87km) to 66.4 km in the case of the GJ and 74.3 km for the elve. These reference heights decreases affected the propagating signal at the disturbed region by increasing the modes attenuation coefficient. Effectively, the number of modes was reduced from 28 at ambient condition to 9 modes (in the case of GJ) and 17 (in the case of elve). This high attenuation of modes leads to the appearance of null signal perturbations positions due to the interferences. Between two null positions

  1. Measuring the upset of CMOS and TTL due to HPM-signals

    Directory of Open Access Journals (Sweden)

    N. Esser


    Full Text Available To measure the performance of electronic components when stressed by High Power Microwave signals a setup was designed and tested which allows a well-defined voltage signal to enter the component during normal operation, and to discriminate its effect on the component. The microwave signal is fed to the outside conductor of a coaxial cable and couples into the inner signal line connected to the device under test (DUT. The disturbing HF-signal is transferred almost independent from frequency to maintain the pulse shape in the time domain. The configuration designed to perform a TEM-coupling within a 50 Ohm system prevents the secondary system from feeding back to the primary system and, due to the geometrical parameters chosen, the coupling efficiency is as high as 50–90%. Linear dimensions and terminations applied allow for pulses up to a width of 12ns and up to a voltage level of 4–5 kV on the outside conductor. These pulse parameters proved to be sufficient to upset the DUTs tested so far. In more than 400 measurements a rectangular pulse of increasing voltage level was applied to different types of CMOS and TTL until the individual DUT was damaged. As well the pulse width (3, 6 or 12 ns and its polarity were varied in single-shot or repetitive-shot experiments (500 shots per voltage at a repetition rate of 3 Hz. The state of the DUT was continuously monitored by measuring both the current of the DUT circuit and that of the oscillator providing the operating signal for the DUT. The results show a very good reproducibility within a set of identical samples, remarkable differences between manufacturers and lower thresholds for repetitive testing, which indicates a memory effect of the DUT to exist for voltage levels significantly below the single-shot threshold.

  2. Estimation of fuel loss due to idling of vehicles at a signalized intersection in Chennai, India (United States)

    Vasantha Kumar, S.; Gulati, Himanshu; Arora, Shivam


    The vehicles while waiting at signalized intersections are generally found to be in idling condition, i.e., not switching off their vehicles during red times. This phenomenon of idling of vehicles during red times at signalized intersections may lead to huge economic loss as lot of fuel is consumed by vehicles when they are in idling condition. The situation may even be worse in countries like India as different vehicle types consume varying amount of fuel. Only limited studies have been reported on estimation of fuel loss due to idling of vehicles in India. In the present study, one of the busy intersections in Chennai, namely, Tidel Park Junction in Rajiv Gandhi salai was considered. Data collection was carried out in one approach road of the intersection during morning and evening peak hours on a typical working day by manually noting down the red timings of each cycle and the corresponding number of two-wheelers, three-wheelers, passenger cars, light commercial vehicles (LCV) and heavy motorized vehicles (HMV) that were in idling mode. Using the fuel consumption values of various vehicles types suggested by Central Road Research Institute (CRRI), the total fuel loss during the study period was found to be Rs. 4,93,849/-. The installation of red timers, synchronization of signals, use of non-motorized transport for short trips and public awareness are some of the measures which government need to focus to save the fuel wasted at signalized intersections in major cities of India.

  3. Statistical properties of the Stokes signal in stimulated Brillouin scattering pulse compressors

    NARCIS (Netherlands)

    Velchev, I.; Ubachs, W.M.G.


    Spontaneous scattering noise is incorporated as a build-up source in a fully transient stimulated Brillouin scattering (SBS) model. This powerful simulation tool is successfully applied for a quantitative investigation of the fluctuations in the output pulse duration of SBS pulse compressors. The

  4. Determination of scattering center of multipath signals using geometric optics and Fresnel zone concepts

    Directory of Open Access Journals (Sweden)

    Kamil Yavuz Kapusuz


    Full Text Available In this study, a method for determining scattering center (or center of scattering points of a multipath is proposed, provided that the direction of arrival of the multipath is known by the receiver. The method is based on classical electromagnetic wave principles in order to determine scattering center over irregular terrain. Geometrical optics (GO along with Fresnel zone concept is employed, as the receiver, the transmitter positions and irregular terrain data are assumed to be provided. The proposed method could be used at UHF bands, especially, operations of radars and electronic warfare applications.

  5. Vertical spatial coherence model for a transient signal forward-scattered from the sea surface (United States)

    Yoerger, E.J.; McDaniel, S.T.


    The treatment of acoustic energy forward scattered from the sea surface, which is modeled as a random communications scatter channel, is the basis for developing an expression for the time-dependent coherence function across a vertical receiving array. The derivation of this model uses linear filter theory applied to the Fresnel-corrected Kirchhoff approximation in obtaining an equation for the covariance function for the forward-scattered problem. The resulting formulation is used to study the dependence of the covariance on experimental and environmental factors. The modeled coherence functions are then formed for various geometrical and environmental parameters and compared to experimental data.

  6. Direct Observations of GPS L1 Signal-to-Noise Degradation due to Solar Radio Bursts (United States)

    Cerruti, A. P.; Kintner, P. M.; Gary, D.; Lanzerotti, L.


    GPS signals, systems, and navigation accuracy are vulnerable to a variety of space weather effects mostly caused by the ionosphere. This paper considers a different class of space weather effects on GPS signals: solar radio bursts. We present the first direct observations of GPS L1 (1.6 GHz) carrier-to-noise degradation on two different models of GPS receivers due to the solar radio burst associated with the 7 September, 2005 solar flare. The solar radio burst consisted of two periods of 1.6 GHz activity at approximately 17:40 UT and again at 18:30 UT. All the receivers that were affected by the solar radio burst were in the sun-lit hemisphere: three identical receivers were collocated at the Arecibo Observatory, and four identical receivers of a different model were located in Brazil. For both models, all GPS satellites in view were affected similarly. In some cases the decrease in the GPS L1 signal-to-noise agreed perfectly with the solar radio burst amplitudes, while in other cases there was no association. Further analysis indicated that only the right hand circularly polarized (RHCP) emissions affected the GPS signals. Since GPS signals are RHCP and GPS antennas are also RHCP, the null effect of the LHCP power confirms our hypothesis that the solar radio bursts are causal. The maximum solar radio burst power associated with the 7 September 2005 flare had a peak intensity of about 8,700 solar flux units (SFU) RHCP at 1,600 MHz, which caused a corresponding decrease in the signal- to-noise of about 2.5 dB across all visible satellites. Furthermore, an event with a peak intensity of 5,000 SFU RHCP at 1,600 MHz caused a 2 dB fade for nearly 15 minutes. To further investigate the effect of solar radio bursts, we also examined the emissions associated with the 28 October 2003 flare. Although polarization data was not available for this even, a similar association was found between 1,400 MHz solar radio power and GPS signal-to-noise degradation. The maximum


    This report is a collection of three papers on two subjects: the scattering of acoustic waves from rough surfaces and the time variation of ambient ...experimental program to investigate the time variation of low-frequency ambient sea noise. (Author)

  8. A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner, E-mail: [Institut für Biophysik, Goethe-Universität Frankfurt am Main, Max-von Laue-Straße 1, D-60438 Frankfurt am Main (Germany)


    A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

  9. A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins (United States)

    Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner


    A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

  10. The signal in total-body plethysmography: errors due to adiabatic-isothermic difference. (United States)

    Chaui-Berlinck, J G; Bicudo, J E


    Total-body plethysmography is a technique often employed in comparative physiology studies because it avoids excessive handling of the animals. The pressure signal obtained is generated by an increase in internal energy of the gas phase of the system. Currently, this increase in internal energy is ascribed to heating (and water vapour saturation) of the inspired gas. The standard equation for computing tidal-volume implies that only temperature and saturation differences can be responsible for generating the ventilation signal. In this study, we were able to demonstrate that the difference between the external process of the thoracic expansion, which is adiabatic, and the internal process of it, which is isothermic, is an important factor of internal energy change in the total-body plethysmography method. In other words, organic tissues transfer heat to the entering gas but also to the present gas, in a way that keeps internal expansion an isothermic process. This extra amount of energy was never taken into account before. Therefore, experiments using such a technique to measure tidal-volume should be done using isothermic chambers. Moreover, due to uncertainties of the complementary measurements (ambient and lung temperatures, ambient water vapour saturation) needed to compute tidal-volume using total-body plethysmography, a minimal temperature difference about 15 degrees C between body and ambient should exist to keep uncertainties in tidal-volume values below 5%. However, this limit is not absolute, because it varies as a function of humidity and degree of uncertainty of the complementary measurements.

  11. Resonant absorption of electromagnetic radiation in a quantum channel due to the scattering of electrons by impurities (United States)

    Karpunin, V. V.; Margulis, V. A.


    We have found an analytical expression for the absorption coefficient of electromagnetic radiation in a quantum channel with a parabolic confinement potential. The calculation has been performed using the second-order perturbation theory taking into account the scattering of a quasi-one-dimensional electron gas by ionized impurities. We have analyzed the dependences of the absorption coefficient on the frequency of the electromagnetic radiation and the magnetic field. The appearance of additional resonant peaks, which are caused by scattering by impurities, has been found.

  12. Self phase modulation and stimulated raman scattering due to high power femtosecond pulse propagation in silicon-on-insulator waveguides

    NARCIS (Netherlands)

    Mégret, P.; Dekker, R.; Wuilpart, M.; Klein, E.J.; Niehusmann, J.; Bette, S.; Staquet, N.; Först, M.; Ondracek, F.; Ctyroky, J.; Usechak, N.; Driessen, A.


    Self Phase Modulation (SPM) and Stimulated Raman Scattering (SRS) in silicon waveguides have been observed and will be discussed theoretically using a modified Nonlinear Schrödinger Equation. The high optical peak powers needed for the experiments were obtained by coupling sub-picosecond (200fs)

  13. Extreme obesity due to impaired leptin signaling in mice does not cause knee osteoarthritis. (United States)

    Griffin, Timothy M; Huebner, Janet L; Kraus, Virginia B; Guilak, Farshid


    To test the hypothesis that obesity resulting from deletion of the leptin gene or the leptin receptor gene results in increased knee osteoarthritis (OA), systemic inflammation, and altered subchondral bone morphology. Leptin-deficient (ob/ob) and leptin receptor-deficient (db/db) female mice compared with wild-type mice were studied, to document knee OA via histopathology. The levels of serum proinflammatory and antiinflammatory cytokines were measured using a multiplex bead immunoassay. Cortical and trabecular subchondral bone changes were documented by microfocal computed tomography, and body composition was quantified by dual x-ray absorptiometry. Adiposity was increased by approximately 10-fold in ob/ob and db/db mice compared with controls, but it was not associated with an increased incidence of knee OA. Serum cytokine levels were unchanged in ob/ob and db/db mice relative to controls, except for the level of cytokine-induced neutrophil chemoattractant (keratinocyte chemoattractant; murine analog of interleukin-8), which was elevated. Leptin impairment was associated with reduced subchondral bone thickness and increased relative trabecular bone volume in the tibial epiphysis. Extreme obesity due to impaired leptin signaling induced alterations in subchondral bone morphology without increasing the incidence of knee OA. Systemic inflammatory cytokine levels remained largely unchanged in ob/ob and db/db mice. These findings suggest that body fat, in and of itself, may not be a risk factor for joint degeneration, because adiposity in the absence of leptin signaling is insufficient to induce systemic inflammation and knee OA in female C57BL/6J mice. These results imply a pleiotropic role of leptin in the development of OA by regulating both the skeletal and immune systems.

  14. [The Mie scattering lidar return signal denoising research based on EMD-DISPO]. (United States)

    Zhang, Yi-Kun; Ma, Xiao-Chang; Hua, Deng-Xin; Chen, Hao; Liu, Cai-Xuan


    Lidar echo signal is a typical non-steady-state, non-stationary signal, and difficult to be dealt with by the traditional filtering methods. As a new signal processing theory proposed in recent years, empirical mode decomposition method can adaptively divide the lidar echo signal into different intrinsic mode function (IMF) components according to different time scale, and noise mainly concentrates in the high-frequency component. However, when filtered with simply removing high frequency component, the useful signal will be possibly reduced. In the present paper, a new method which combines empirical mode decomposition (EMD) with Savitzky-Golay filter is proposed. With experiments, it is indicated that our approach not only removes the noise component effectively but also maintains the useful signal, then will improve the accuracy in the next phase of data processing.

  15. Effects of admittance and gyrotropy on the scattering due to chiro-ferrite medium coated microstructured PMC cylinder (United States)

    Iqbal, N.; Choudhury, P. K.


    The paper deals with scattering of electromagnetic (EM) waves by perfectly magnetic conducting (PMC) cylinder coated with chiro-ferrite medium under the assumption of oblique angle of incidence wave with perpendicular polarization (transverse electric; TE). An on-demand (in respect of orientation) kind of conducting sheath helix structure is assumed to exist at the outer surface of cylinder. The effects of sheath helix orientation, along with the material parameters, such as chirality admittance and gyrotropy, on the echo width as well as the magnitude and phase of the electric and magnetic fields are investigated. Control on the anisotropic property remains greatly useful in obtaining the required optical response from the scatterer - the feature which would find fabulous sensing related applications.

  16. Cortical light scattering during interictal epileptic spikes in frontal lobe epilepsy in children: A fast optical signal and electroencephalographic study. (United States)

    Manoochehri, Mana; Mahmoudzadeh, Mahdi; Bourel-Ponchel, Emilie; Wallois, Fabrice


    Interictal epileptic spikes (IES) represent a signature of the transient synchronous and excessive discharge of a large ensemble of cortical heterogeneous neurons. Epilepsy cannot be reduced to a hypersynchronous activation of neurons whose functioning is impaired, resulting on electroencephalogram (EEG) in epileptic seizures or IES. The complex pathophysiological mechanisms require a global approach to the interactions between neural synaptic and nonsynaptic, vascular, and metabolic systems. In the present study, we focused on the interaction between synaptic and nonsynaptic mechanisms through the simultaneous noninvasive multimodal multiscale recording of high-density EEG (HD-EEG; synaptic) and fast optical signal (FOS; nonsynaptic), which evaluate rapid changes in light scattering related to changes in membrane configuration occurring during neuronal activation of IES. To evaluate changes in light scattering occurring around IES, three children with frontal IES were simultaneously recorded with HD-EEG and FOS. To evaluate change in synchronization, time-frequency representation analysis of the HD-EEG was performed simultaneously around the IES. To independently evaluate our multimodal method, a control experiment with somatosensory stimuli was designed and applied to five healthy volunteers. Alternating increase-decrease-increase in optical signals occurred 200 ms before to 180 ms after the IES peak. These changes started before any changes in EEG signal. In addition, time-frequency domain EEG analysis revealed alternating decrease-increase-decrease in the EEG spectral power concomitantly with changes in the optical signal during IES. These results suggest a relationship between (de)synchronization and neuronal volume changes in frontal lobe epilepsy during IES. These changes in the neuronal environment around IES in frontal lobe epilepsy observed in children, as they have been in rats, raise new questions about the synaptic/nonsynaptic mechanisms that propel

  17. Study of probing beam enlargement due to forward-scattering under low wavenumber turbulence using a FDTD full-wave code

    Energy Technology Data Exchange (ETDEWEB)

    Silva, F. da [Associao EURATOM/IST, IPFN-LA, Instituto Superor Tecnico, Lisbon (Portugal); Heuraux, S. [Institut Jean Lamour, CNRS-Nancy-Universite, BP70239, Vandoeuvre-les-Nancy (France); Gusakov, E.; Popov, A. [Ioffe Institute, Polytekhnicheskaya, St Petersburg (Russian Federation)


    Forward-scattering under high level of turbulence or long propagation paths can induce significant effects, as predicted by theory, and impose a signature on the Doppler reflectometry response. Simulations using a FDTD (finite-difference time-domain) full-wave code have confirmed the main dependencies and general behavior described by theory but display a returned RMS power, at moderate amplitudes, half of the one predicted by theory due to the impossibility to reach the numerical requirements needed to describe the small wavenumber spectrum with the wanted accuracy.One justifying factor may be due to the splitting and enlargement of the probing beam. At high turbulence levels, the scattered power returning to the antenna is higher than the predicted by the theory probably due to the scattered zone being closer than the oblique cutoff. This loss of coherence of the wavefront induces a beam spreading, which is also responsible for a diminution of the wavenumber resolution. With a FDTD full-wave code we study the behavior of the probing beam under several amplitude levels of low wavenumber plasma turbulence, using long temporal simulations series to ensure statistical accuracy. (authors)

  18. Insulin signaling disruption in male mice due to perinatal bisphenol A exposure: Role of insulin signaling in the brain. (United States)

    Fang, Fangfang; Gao, Yue; Wang, Tingwei; Chen, Donglong; Liu, Jingli; Qian, Wenyi; Cheng, Jie; Gao, Rong; Wang, Jun; Xiao, Hang


    Bisphenol A (BPA), an environmental estrogenic endocrine disruptor, is widely used for producing polycarbonate plastics and epoxy resins. Available data have shown that perinatal exposure to BPA contributes to peripheral insulin resistance, while in the present study, we aimed to investigate the effects of perinatal BPA exposure on insulin signaling and glucose transport in the cortex of offspring mice. The pregnant mice were administrated either vehicle or BPA (100 μg/kg/day) at three perinatal stages. Stage I: from day 6 of gestation until parturition (P6-PND0 fetus exposure); Stage II: from lactation until delactation (PND0-PND21 newborn exposure) and Stage III: from day 6 of pregnancy until delactation (P6-PND21 fetus and newborn exposure). At 8 months of age for the offspring mice, the insulin signaling pathways and glucose transporters (GLUTs) were detected. Our data indicated that the insulin signaling including insulin, phosphorylated insulin receptor (IR), phosphorylated protein kinase B (p-AKT), phosphorylated glycogen synthase kinase 3β (p-GSK3β) and phosphorylated extracellular signal regulated protein kinase (p-ERK) were significantly decreased in the brain. In parallel, GLUTs (GLUT1/3/4) were obviously decreased as well in BPA-treated group in mice brain. Noteworthily, the phosphorylated tau (p-tau) and amyloid precursor protein (APP) were markedly up-regulated in all BPA-treated groups. These results, taken together, suggest the adverse effects of BPA on insulin signaling and GLUTs, which might subsequently contribute to the increment of p-tau and APP in the brain of adult offspring. Therefore, perinatal BPA exposure might be a risk factor for the long-term neurodegenerative changes in offspring male mice. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  19. Cortical T2 signal shortening in amyotrophic lateral sclerosis is not due to iron deposits

    Energy Technology Data Exchange (ETDEWEB)

    Hecht, M.J.; Neundoerfer, B. [University of Erlangen-Nurenberg, Department of Neurology, Erlangen (Germany); Fellner, C.; Fellner, F.A. [University of Erlangen-Nurenberg, Institute of Diagnostic Radiology, Erlangen (Germany); Landes-Nervenklinik Wagner-Jauregg, Institute of Radiology, Linz (Austria); Schmid, A. [University of Erlangen-Nurenberg, Institute of Diagnostic Radiology, Erlangen (Germany)


    Signal shortening of the motor cortex in T2-weighted MR images is a frequent finding in patients with amyotrophic lateral sclerosis (ALS). The cause of signal shortening in ALS is unknown, although iron deposits have been suggested. To test this hypothesis, we acquired T2*-weighted gradient-echo (GRE) MR images in addition to T2-weighted turbo spin-echo in 69 patients with ALS. Signal shortening in T2-weighted images was found in 31 patients. In T2*-weighted GRE images, only three patients had signal shortening. One patient with additional bifrontal haemorrhage had frontal but no motor cortex signal shortening. Iron deposits do not cause cortical signal shortening in patients with ALS predominantly. Other factors are presumably more important in the generation of cortical T2 shortening in ALS. (orig.)

  20. Relaxation of a kinetic hole due to carrier-carrier scattering in multisubband single-quantum-well semiconductors

    DEFF Research Database (Denmark)

    Dery, H.; Tromborg, Bjarne; Eisenstein, G.


    We describe a theoretical model for carrier-carrier scattering in an inverted semiconductor quantum well structure using a multisubband diagram. The model includes all possible nonvanishing interaction terms within the static screening approximation, and it enables one to calculate accurately...... the temporal evolution of the carrier densities and the gain following a perturbation by a short optical pulse. We present a theoretical formalism and detailed numerical calculations. The addition of more than one subband in each band as well as the use of all exchange terms yields several results. First...

  1. Degradation of spatial resolution in thin-foil x-ray microchemical analysis due to plural scattering of electrons

    Energy Technology Data Exchange (ETDEWEB)

    Twigg, Mark Erickson [Univ. of Illinois, Urbana-Champaign, IL (United States)


    A computer-based Monte Carlo simulation of incoherent plural scattering of electrons has been developed in order to estimate the broadening of an electron probe as it propagates through a solid. By applying this approach to modeling the spreading of a fine (50 A) probe focused on a thin foil in a scanning transmission electron microscope (STEM), we have estimated the spatial resolution of the compositional analysis obtainable using energy dispersive x-ray spectroscopy (EDS). Specifically, an attempt has been made to determine how the apparent microchemistry of a feature of finer dimensions than the broadened beam differs from the actual composition of the given feature. The apparent Ge concentration profile in the vicinity of a 200 A wide Ge platelet in a 5000 A thick Al foil was measured, using STEM and EDS, and compared with the profile predicted by Monte Carlo calculations. Results are presented and discussed.

  2. GPS Signal Scattering from Sea Surface: Wind Speed Retrieval Using Experimental Data and Theoretical Model (United States)

    Komjathy, Attila; Zavorotny, Valery U.; Axelrad, Penina; Born, George H.; Garrison, James L.


    Global Positioning System (GPS) signals reflected from the ocean surface have potential use for various remote sensing purposes. Some possibilities arc measurements of surface roughness characteristics from which ware height, wind speed, and direction could be determined. For this paper, GPS-reflected signal measurements collected at aircraft altitudes of 2 km to 5 km with a delay-Doppler mapping GPS receiver arc used to explore the possibility of determining wind speed. To interpret the GPS data, a theoretical model has been developed that describes the power of the reflected GPS signals for different time delays and Doppler frequencies as a function of geometrical and environmental parameters. The results indicate a good agreement between the measured and the modeled normalized signal power waveforms during changing surface wind conditions. The estimated wind speed using surface- reflected GPS data, obtained by comparing actual and modeled waveforms, shows good agreement (within 2 m/s) with data obtained from a nearby buoy and independent wind speed measurements derived from the TOPEX/Poseidon altimetric satellite.

  3. 1 Tbit/inch2 Recording in Angular-Multiplexing Holographic Memory with Constant Signal-to-Scatter Ratio Schedule (United States)

    Hosaka, Makoto; Ishii, Toshiki; Tanaka, Asato; Koga, Shogo; Hoshizawa, Taku


    We developed an iterative method for optimizing the exposure schedule to obtain a constant signal-to-scatter ratio (SSR) to accommodate various recording conditions and achieve high-density recording. 192 binary images were recorded in the same location of a medium in approximately 300×300 µm2 using an experimental system embedded with a blue laser diode with a 405 nm wavelength and an objective lens with a 0.85 numerical aperture. The recording density of this multiplexing corresponds to 1 Tbit/in.2. The recording exposure time was optimized through the iteration of a three-step sequence consisting of total reproduced intensity measurement, target signal calculation, and recording energy density calculation. The SSR of pages recorded with this method was almost constant throughout the entire range of the reference beam angle. The signal-to-noise ratio of the sampled pages was over 2.9 dB, which is higher than the reproducible limit of 1.5 dB in our experimental system.

  4. Coronary artery stent mimicking intracardiac thrombus on cardiac magnetic resonance imaging due to signal loss

    DEFF Research Database (Denmark)

    Qayyum, Abbas Ali; Vejlstrup, Niels Grove; Ahtarovski, Kiril Aleksov


    Since the introduction of percutaneous coronary intervention for coronary artery disease, thousands of patients have been treated with the implantation of coronary stents. Moreover, several of the patients with coronary stent undergo cardiac magnetic resonance (CMR) imaging every year. This case ...... the signal loss on MRI associated with implanted metallic devices is known, we report a case where an implanted coronary stent in the left circumflex artery led to an intracardiac signal loss mimicking intracardiac thrombus/tumor....

  5. Single Trial Classification of Evoked EEG Signals Due to RGB Colors

    Directory of Open Access Journals (Sweden)

    Eman Alharbi


    Full Text Available Recently, the impact of colors on the brain signals has become one of the leading researches in BCI systems. These researches are based on studying the brain behavior after color stimulus, and finding a way to classify its signals offline without considering the real time. Moving to the next step, we present a real time classification model (online for EEG signals evoked by RGB colors stimuli, which is not presented in previous studies. In this research, EEG signals were recorded from 7 subjects through BCI2000 toolbox. The Empirical Mode Decomposition (EMD technique was used at the signal analysis stage. Various feature extraction methods were investigated to find the best and reliable set, including Event-related spectral perturbations (ERSP, Target mean with Feast Fourier Transform (FFT, Wavelet Packet Decomposition (WPD, Auto Regressive model (AR and EMD residual. A new feature selection method was created based on the peak's time of EEG signal when red and blue colors stimuli are presented. The ERP image was used to find out the peak's time, which was around 300 ms for the red color and around 450 ms for the blue color. The classification was performed using the Support Vector Machine (SVM classifier, LIBSVM toolbox being used for that purpose. The EMD residual was found to be the most reliable method that gives the highest classification accuracy with an average of 88.5% and with an execution time of only 14 seconds.

  6. Analysis of guided wave scattering due to defects in rails using a hybrid FE-safe method (United States)

    Long, C. S.; Loveday, P. W.


    Analysis of travelling waves in elastic waveguides with complex cross-sections, such as train rails, can only conveniently be performed numerically. The semi-analytical finite element (SAFE) method has become a popular tool for performing such analyses. This paper employs a hybrid SAFE-3D FE method to investigate the scattering of guided waves at discontinuities such as welds or cracks, in continuous welded train rails. The aim of the analysis is to predict transmission and reflection coefficients for a given incident wave and known discontinuity. This characterisation is useful for predicting the long-range transmission characteristics of transducers in non-destructive evaluation (NDE) and monitoring systems, such as the ultrasonic broken rail detector (UBRD) system developed by the Institute for Maritime Technology (IMT) and the Council for Scientific and Industrial Research (CSIR). Furthermore, we investigate an extension of the current UBRD system to detect cracks before complete breaks occur, which will require distinguishing between reflections from cracks and other reflectors such as welds, in order to avoid false alarms.

  7. Ultrasound (US transducer of higher operating frequency detects photoacoustic (PA signals due to the contrast in elastic property

    Directory of Open Access Journals (Sweden)

    Mayanglambam Suheshkumar Singh


    Full Text Available We report our study that shows selection in operating frequency of US-transducer used for boundary detection of PA-signals, which result due to the contrast in elastic property distribution ( E ( r → in sample material other than that of optical absorption coefficient (μa. Studies were carried out, experimentally, in tissue-mimicking Agar phantoms employing acoustic resolution photoacoustic microscopy (AR-PAM system as an imaging unit. In the experiments, various transducers having different operating frequencies, ranging from 1MHz to 50MHz, were employed for studying frequency response of the photoacoustic signals. The study shows that, for detecting photoacoustic signals due to the contrast in elastic property, ultrasound transducer with higher operating frequency (∼50MHz is demanded.

  8. Beam loss and backgrounds in the CDF and D0 detectors due to nuclear elastic beam-gas scattering

    Energy Technology Data Exchange (ETDEWEB)

    Alexandr I. Drozhdin; Valery A. Lebedev; Nikolai V. Mokhov


    Detailed simulations were performed on beam loss rates in the vicinity of the Tevatron Collider detectors due to beam-gas nuclear elastic interactions. It turns out that this component can drive the accelerator-related background rates in the CDF and D0 detectors, exceeding those due to outscattering from collimation system, inelastic beam-gas interactions and other processes [1, 2]. Results of realistic simulations with the STRUCT and MARS codes are presented for the interaction region components and the CDF and D0 detectors. It is shown that a steel mask placed upstream of the detectors can reduce the background rates by almost an order of magnitude.

  9. Cetuximab insufficiently inhibits glioma cell growth due to persistent EGFR downstream signaling

    DEFF Research Database (Denmark)

    Hasselbalch, Benedikte; Lassen, Ulrik; Poulsen, Hans S


    Overexpression and/or amplification of the epidermal growth factor receptor (EGFR) is present in 35-45% of primary glioblastoma multiforme tumors and has been correlated with a poor prognosis. In this study, we investigated the effect of cetuximab and intracellular signaling pathways downstream...

  10. Electron density increase due to QEF and comparison between the reference height lifetime and the VLF signal perturbations (United States)

    Nait Amor, Samir; Bouderba, Yasmina


    In this contribution we will present a new result on the atmospheric ionisation due to QEF by considering the real values of the electric filed breakdown. Since the refence height of the VLF signal propagation is at 87 km, the numerical results showed that the ionisation started at 86 km and below for a lower QEF amplitudes. The reference height build-up time decreases to the stationary value of 20ms in agreement with the recorded ealry/fast VLF signal perturbations. For QEF values greater than 35 V/m the ionisation increase drastically and therefore the reference height is formed at lower altitudes (80 and 78 km). Since mutliple reference heights are formed and are capable to reflect the VLF signal, the corresponding signal perturbation time recovery is then the sum of all lifetimes of the reference heights.

  11. What can we learn from HF signal scattered from a discrete arc?

    Directory of Open Access Journals (Sweden)

    E. Séran


    Full Text Available We present observations of a discrete southward propagating arc which appeared in the mid-night sector at latitudes equatorward of main substorm activity. The arc observations were made simultaneously by the ALFA (Auroral Light Fine Analysis optical camera, the SuperDARN-CUTLASS HF radar and the Demeter satellite during a coordinated multi-instrumental campaign conducted at the KEOPS/ESRANGE site in December 2006. The SuperDARN HF signal which is often lost in the regions of strong electron precipitation yields in our case clear backscatter from an isolated arc of weak intensity. Consequently we are able to study arc dynamics, the formation of meso-scale irregularities of the electron density along the arc, compare the arc motion with the convection of surrounding plasma and discuss the contribution of ionospheric ions in the arc erosion and its propagation.

  12. Degradation of signal to noise ratio in optical free space data links due to background illumination. (United States)

    Leeb, W R


    In free space optical data transmission systems illumination of the receiver antenna by background radiation will decrease the signal to noise ratio. We derive expressions for that degradation both for direct and for heterodyne/homodyne receivers. Examples are given for cases where the sun, the moon, the earth, and Venus illuminate earth orbiting receivers operating at wavelengths of 0.85 microm, 1.3 microm, and 10.6 microm. Direct detection receivers will typically suffer a degradation of between 5 and 15 dB at lambda = 0.85 microm and lambda = 1.3 microm when illuminated by the sun. Heterodyne/homodyne receivers at 10.6 microm degrade more with sun radiation (typically 4 dB) than at the smaller wavelengths ( approximately 0.3 dB). The moon, earth, and Venus cause negligible reduction of signal to noise ratio.

  13. Infrared characterization of hot spots in solar cells with high precision due to signal treatment processing

    Energy Technology Data Exchange (ETDEWEB)

    Kaminski, A.; Jouglar, J.; Mergui, M.; Jourlin, Y.; Bouille, A.; Vuillermoz, P.L.; Laugier, A. [Institute National des Sciences Appliquees, Laboratoire de Physique de la Matiere-UMR, Villeurbanne (France)


    In this paper we show how to improve greatly the resolution of IR thermography by using two different signal treatment methods: a static treatment and a dynamical treatment. This signal processing allows the study of 100 cm{sup 2} cells under low-forward or reverse-polarization conditions. Static and dynamical methods have both good resolutions: static has the advantage of being fast, and dynamical method does not need any reference image nor cooling system. We have shown that IR thermography is an interesting method for investigating shunts in solar cells. Thermal maps and I-V characterization of the hot spots show that the origin and the behavior of the shunts are varied and their influence on the efficiency is probably more important than what is usually thought

  14. Diffuse light reflectance signals as potential indicators of loss of viability in brain tissue due to hypoxia: charge-coupled-device-based imaging and fiber-based measurement. (United States)

    Kawauchi, Satoko; Nishidate, Izumi; Uozumi, Yoichi; Nawashiro, Hiroshi; Ashida, Hiroshi; Sato, Shunichi


    Brain tissue is highly vulnerable to ischemia/hypoxia, and real-time monitoring of its viability is important. By fiber-based measurements for rat brain, we previously observed a unique triphasic reflectance change (TRC) after a certain period of time after hypoxia. After TRC, rats could not be rescued, suggesting that TRC can be used as an indicator of loss of brain tissue viability. In this study, we investigated this diffuse-reflectance change due to hypoxia in three parts. First, we developed and validated a theoretical method to quantify changes in the absorption and reduced scattering coefficients involved in TRC. Second, we performed charge-coupled-device-based reflectance imaging of the rat brain during hypoxia followed by reoxygenation to examine spatiotemporal characteristics of the reflectance and its correlation with reversibility of brain tissue damage. Third, we made simultaneous imaging and fiber-based measurement of the reflectance for the rat to compare signals obtained by these two modalities. We observed a nontriphasic reflectance change by the imaging, and it was associated with brain tissue viability. We found that TRC measured by the fibers preceded the reflectance-signal change captured by the imaging. This time difference is attributable to the different observation depths in the brain with these two methods.

  15. High-Efficiency Nanowire Solar Cells with Omnidirectionally Enhanced Absorption Due to Self-Aligned Indium-Tin-Oxide Mie Scatterers. (United States)

    van Dam, Dick; van Hoof, Niels J J; Cui, Yingchao; van Veldhoven, Peter J; Bakkers, Erik P A M; Gómez Rivas, Jaime; Haverkort, Jos E M


    Photovoltaic cells based on arrays of semiconductor nanowires promise efficiencies comparable or even better than their planar counterparts with much less material. One reason for the high efficiencies is their large absorption cross section, but until recently the photocurrent has been limited to less than 70% of the theoretical maximum. Here we enhance the absorption in indium phosphide (InP) nanowire solar cells by employing broadband forward scattering of self-aligned nanoparticles on top of the transparent top contact layer. This results in a nanowire solar cell with a photovoltaic conversion efficiency of 17.8% and a short-circuit current of 29.3 mA/cm(2) under 1 sun illumination, which is the highest reported so far for nanowire solar cells and among the highest reported for III-V solar cells. We also measure the angle-dependent photocurrent, using time-reversed Fourier microscopy, and demonstrate a broadband and omnidirectional absorption enhancement for unpolarized light up to 60° with a wavelength average of 12% due to Mie scattering. These results unambiguously demonstrate the potential of semiconductor nanowires as nanostructures for the next generation of photovoltaic devices.

  16. VLF signal perturbation due to the total solar eclipse of March 2015 (United States)

    Nait Amor, Samir; Bouderba, Yasmina


    On March 20 2015 a total Solar eclipse occurred and covered several regions in north America, Greenland, west of Europe and north Africa with different occultation rates. During this event, many VLF paths recorded at Algiers receiver were perturbed. In this contribution, we will present a qualitative analysis of two paths (GQD and DHO) which were disturbed differently since the occultation rate at the transmitter locations was different. In addition to the qualitative study, we determined the newly formed reference height and β values at different times during the eclipse transit. From these determined parameters the time profile of the electron density is then deduced. The results showed that the new reference height, β and the electron density are different from one transmitter analysis to other due to the occultation rate difference.

  17. Crustal movements due to Iceland's shrinking ice caps mimic magma inflow signal at Katla volcano. (United States)

    Spaans, Karsten; Hreinsdóttir, Sigrún; Hooper, Andrew; Ófeigsson, Benedikt Gunnar


    Many volcanic systems around the world are located beneath, or in close proximity to, ice caps. Mass change of these ice caps causes surface movements, which are typically neglected when interpreting surface deformation measurements around these volcanoes. These movements can however be significant, and may closely resemble movements due to magma accumulation. Here we show such an example, from Katla volcano, Iceland. Horizontal movements observed by GPS on the flank of Katla have led to the inference of significant inflow of magma into a chamber beneath the caldera, starting in 2000, and continuing over several years. We use satellite radar interferometry and GPS data to show that between 2001 and 2010, the horizontal movements seen on the flank can be explained by the response to the long term shrinking of ice caps, and that erratic movements seen at stations within the caldera are also not likely to signify magma inflow. It is important that interpretations of geodetic measurements at volcanoes in glaciated areas consider the effect of ice mass change, and previous studies should be carefully reevaluated.

  18. Improving detection and identification of seismic signals due to landslides: a methodology based on field scale controlled experiments (United States)

    Yfantis, G.; Carvajal, H. E.; Pytharouli, S.; Lunn, R. J.


    A number of published studies use seismic sensors to understand the physics involved in slope deformation. In this research we artificially induce failure to two meter scaled slopes in the field and use 12 short period 3D seismometers to monitor the failure. To our knowledge there has been no previous controlled experiments that can allow calibration and validation of the interpreted seismic signals. Inside the body of one of the artificial landslides we embed a pile of glass shards. During movement the pile deforms emitting seismic signals due to friction among the glass shards. Our aim is twofold: First we investigate whether the seismic sensors can record pre-cursory and failure signals. Secondly, we test our hypothesis that the glass shards produce seismic signals with higher amplitudes and a distinct frequency pattern, compared to those emitted by common landslide seismicity and local background noise. Two vertical faces, 2m high, were excavated 3m apart in high porous tropical clay. This highly attenuating material makes the detection of weak seismic signals challenging. Slope failure was induced by increasing the vertical load at the landslide's crown. Special care was taken in the design of all experimental procedures to not add to the area's seismic noise. Measurements took place during 18 hours (during afternoon and night) without any change in soil and weather conditions. The 3D sensors were placed on the ground surface close to the crown, forming a dense microseismic network with 5-to-10m spacing and two nanoseismic arrays, with aperture sizes of 10 and 20 m. This design allowed a direct comparison of the recorded signals emitted by the two landslides. The two faces failed for loading between 70 and 100kN and as a result the pile of glass shards was horizontally deformed allowing differential movement between the shards. After the main failure both landslides were continuing to deform due to soil compaction and horizontal displacement. We apply signal

  19. On the Inversion of the Scattering Polarization and the Hanle Effect Signals in the Hydrogen Lyalpha Line

    Czech Academy of Sciences Publication Activity Database

    Ishikawa, R.; Ramos, A.A.; Belluzzi, L.; Manso Sainz, R.; Štěpán, Jiří; Trujillo Bueno, J.; Goto, M.; Tsuneta, S.


    Roč. 787, č. 2 (2014), 159/1-159/11 ISSN 0004-637X R&D Projects: GA ČR GPP209/12/P741 Institutional support: RVO:67985815 Keywords : magnetic fields * polarization * scattering Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.993, year: 2014

  20. Inverse Compton Scattered Merger-nova: Late X-Ray Counterpart of Gravitational-wave Signals from NS–NS/BH Mergers (United States)

    Ai, Shunke; Gao, He


    The recent observations of GW170817 and its electromagnetic (EM) counterparts show that double neutron star mergers could lead to rich and bright EM emissions. Recent numerical simulations suggest that neutron star and neutron star/black hole (NS–NS/BH) mergers would leave behind a central remnant surrounded by a mildly isotropic ejecta. The central remnant could launch a collimated jet and when the jet propagates through the ejecta, a mildly relativistic cocoon would be formed and the interaction between the cocoon and the ambient medium would accelerate electrons via external shock in a wide angle, so that the merger-nova photons (i.e., thermal emission from the ejecta) would be scattered into higher frequency via an inverse Compton (IC) process when they propagate through the cocoon shocked region. We find that the IC scattered component peaks at the X-ray band and it will reach its peak luminosity on the order of days (simultaneously with the merger-nova emission). With current X-ray detectors, such a late X-ray component could be detected out to 200 Mpc, depending on the merger remnant properties. It could serve as an important electromagnetic counterpart of gravitational-wave signals from NS–NS/BH mergers. Nevertheless, simultaneous detection of such a late X-ray signal and the merger-nova signal could shed light on the cocoon properties and the concrete structure of the jet.

  1. Non-coherent continuum scattering as a line polarization mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Del Pino Alemán, T.; Manso Sainz, R.; Trujillo Bueno, J., E-mail:, E-mail:, E-mail: [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)


    Line scattering polarization can be strongly affected by Rayleigh scattering at neutral hydrogen and Thomson scattering at free electrons. Often a depolarization of the continuum results, but the Doppler redistribution produced by the continuum scatterers, which are light (hence, fast), induces more complex interactions between the polarization in spectral lines and in the continuum. Here we formulate and solve the radiative transfer problem of scattering line polarization with non-coherent continuum scattering consistently. The problem is formulated within the spherical tensor representation of atomic and light polarization. The numerical method of solution is a generalization of the Accelerated Lambda Iteration that is applied to both the atomic system and the radiation field. We show that the redistribution of the spectral line radiation due to the non-coherence of the continuum scattering may modify the shape of the emergent fractional linear polarization patterns significantly, even yielding polarization signals above the continuum level in intrinsically unpolarizable lines.

  2. On backward scattering of acoustic waves in a turbulent atmosphere and intensity of SODAR echo-signals

    Energy Technology Data Exchange (ETDEWEB)

    Rusakov, Yu.S. [Science and Production Association Typhoon, Obninsk (Russian Federation)


    The backscattering of acoustic waves in the atmosphere has been studied with an absolutely calibrated sodar and a measuring complex at a 300-m meteorological mast (HMM). It has been shown that the backward differential cross-section of the atmosphere and excess attenuation of sound are by an order of magnitude greater than formerly recognized. The effects have been qualitatively justified on the basis of consideration of the small-scale turbulence intermittence and a model of sound scattering on the ensemble of local inhomogeneities. (orig.)

  3. Influence of statistical surface models on dynamic scattering of high-frequency signals from the ocean surface (A)

    DEFF Research Database (Denmark)

    Bjerrum-Niese, Christian; Jensen, Leif Bjørnø


    ; the surface roughness is described by a spatial surface spectrum and the surface motion is described by the gravity-wave dispersion relation [D. Dowling and D. Jackson, J. Acoust. Soc. Am. 93, 3149–3157 (1993)]. Applying some modifications to this approach, the temporal coherence function is found...... for the Pierson–Moskowitz spectrum (for a fully developed sea) with computations for the JONSWAP spectrum (for fetch-limited seas). The following results, among other issues, have been obtained: As the fetch decreases, the surface waves become shorter, leading to increasing frequency shifting of the scattered...

  4. Adaptive adjustment of reference constellation for demodulating 16QAM signal with intrinsic distortion due to imperfect modulation. (United States)

    Inoue, Takashi; Namiki, Shu


    We find that an adaptive equalizer and a phase-locked loop operating with decision-directed mode exhibit degraded performances when they are used in a digital coherent receiver to demodulate a 16QAM signal with intrinsically distorted constellation, and that the degradation is more significant for the dual-polarization case. We then propose a scheme to correctly demodulate such a distorted 16QAM signal, where the reference constellation and the threshold for the decision are adaptively adjusted such that they fit to the distorted ones. We experimentally confirm the improved performance of the proposed scheme over the conventional one for single-and dual-polarization 16QAM signals with distortion. We also investigate the applicable range of the proposed scheme for the degree of distortion of the signal.

  5. A large Raman scattering cross-section molecular embedded SERS aptasensor for ultrasensitive Aflatoxin B1 detection using CS-Fe3O4 for signal enrichment (United States)

    Chen, Quansheng; Yang, Mingxiu; Yang, Xiaojing; Li, Huanhuan; Guo, Zhiming; Rahma, M. H.


    With growing concern on oil safety problems, developing a simple and sensitive method to detect Aflatoxin B1 (AFB1), a common mycotoxin in peanut oil, is very necessary. In this study, Surface-enhanced Raman Scattering (SERS) aptasensor was developed for ultrasensitive AFB1 detection using the amino-terminal AFB1 aptamer (NH2-DNA1); and thiol-terminal AFB1 complementary aptamer (SH-DNA2) conjugated magnetic-beads (CS-Fe3O4) as enrichment nanoprobe and AuNR@DNTB@Ag nanorods (ADANRs) as reporter nanoprobe respectively. 5,5‧-Dithiobis(2-nitrobenzoicacid) (DNTB) with large Raman scattering cross-section and no fluorescence interference was embedded in Au and Ag core/shell nanorods as Raman reporter molecules. CS-Fe3O4 possessed excellent biocompatibility and superparamagnetism for rapid signal enrichment. Therefore, NH2-DNA1-CS-Fe3O4 and SH-DNA2-ADANRs were fabricated via the hybrid reaction between aptamers and complementary aptamers. When there is AFB1, AFB1 would competitively combine with the NH2-DNA1-CS-Fe3O4 inducing the dissociation of SH-DNA2-ADANRs from CS-Fe3O4 and further decreasing the SERS signal. Based on this developed SERS aptasensor, a low limit of 0.0036 ng/mL and an effective linear detection range from 0.01 to 100 ng/mL with the correlation coefficient up to 0.986 for AFB1 detection were obtained. Moreover, the specificity of this SERS aptasensor was demonstrated by detecting other two mycotoxins and its accuracy for AFB1 detection in real peanut oil was further confirmed by standard addition recovery test.

  6. On the inversion of the scattering polarization and the Hanle effect signals in the hydrogen Lyα line

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, R. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Asensio Ramos, A.; Manso Sainz, R.; Trujillo Bueno, J. [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain); Belluzzi, L. [Istituto Ricerche Solari Locarno (IRSOL), via Patocchi, 6605 Locarno Monti (Switzerland); Štěpán, J. [Astronomical Institute of the Academy of Sciences, Fričova 298, 251 65 Ondřejov (Czech Republic); Goto, M. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Tsuneta, S., E-mail: [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan)


    Magnetic field measurements in the upper chromosphere and above, where the gas-to-magnetic pressure ratio β is lower than unity, are essential for understanding the thermal structure and dynamical activity of the solar atmosphere. Recent developments in the theory and numerical modeling of polarization in spectral lines have suggested that information on the magnetic field of the chromosphere-corona transition region could be obtained by measuring the linear polarization of the solar disk radiation at the core of the hydrogen Lyα line at 121.6 nm, which is produced by scattering processes and the Hanle effect. The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) sounding rocket experiment aims to measure the intensity (Stokes I) and the linear polarization profiles (Q/I and U/I) of the hydrogen Lyα line. In this paper, we clarify the information that the Hanle effect can provide by applying a Stokes inversion technique based on a database search. The database contains all theoretical Q/I and U/I profiles calculated in a one-dimensional semi-empirical model of the solar atmosphere for all possible values of the strength, inclination, and azimuth of the magnetic field vector, though this atmospheric region is highly inhomogeneous and dynamic. We focus on understanding the sensitivity of the inversion results to the noise and spectral resolution of the synthetic observations as well as the ambiguities and limitation inherent to the Hanle effect when only the hydrogen Lyα is used. We conclude that spectropolarimetric observations with CLASP can indeed be a suitable diagnostic tool for probing the magnetism of the transition region, especially when complemented with information on the magnetic field azimuth that can be obtained from other instruments.

  7. Advances in the FTU collective Thomson scattering system

    Energy Technology Data Exchange (ETDEWEB)

    Bin, W., E-mail:; Bruschi, A.; Grosso, G.; Alessi, E.; De Angeli, M.; Figini, L.; Garavaglia, S.; Granucci, G.; Lontano, M.; Mellera, V.; Minelli, D.; Moro, A.; Muraro, A.; Nardone, A.; Simonetto, A.; Tartari, U. [Istituto di Fisica del Plasma “P. Caldirola,” Consiglio Nazionale delle Ricerche, Milano (Italy); D’Arcangelo, O.; Castaldo, C.; Centioli, C.; Magagnino, S. [ENEA for EUROfusion, Frascati (Italy); and others


    The new collective Thomson scattering diagnostic installed on the Frascati Tokamak Upgrade device started its first operations in 2014. The ongoing experiments investigate the presence of signals synchronous with rotating tearing mode islands, possibly due to parametric decay processes, and phenomena affecting electron cyclotron beam absorption or scattering measurements. The radiometric system, diagnostic layout, and data acquisition system were improved accordingly. The present status and near-term developments of the diagnostic are presented.

  8. The electrical conductivity of the upper mantle and lithosphere from the magnetic signal due to ocean tidal flow

    DEFF Research Database (Denmark)

    Schnepf, Neesha Regmi; Kuvshinov, Alexey; Grayver, Alexander

    Oceans cover about seventy percent of the Earth and yet the overwhelming majority of seismological or electromagnetic (EM) observatories are found on continents. This provides a challenge for understanding composition, structure, and dynamics of Earth’s lithosphere and upper mantle in oceanic reg...... satellite and seafloor magnetic signals from the M2 ocean tide. With these data we also make an attempt to detect lateral variability of the Earth’s conductivity....

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

    Bixler, Joel N.; Yakovlev, Vladislav V.


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

  10. Scattered radiation in DBT geometries with flexible breast compression paddles: a Monte Carlo simulation study (United States)

    Díaz, Oliver; García, Eloy; Oliver, Arnau; Martí, Joan; Martí, Robert


    Scattered radiation is an undesired signal largely present in most digital breast tomosynthesis (DBT) projection images as no physically rejection methods, i.e. anti-scatter grids, are regularly employed, in contrast to full- field digital mammography. This scatter signal might reduce the visibility of small objects in the image, and potentially affect the detection of small breast lesions. Thus accurate scatter models are needed to minimise the scattered radiation signal via post-processing algorithms. All prior work on scattered radiation estimation has assumed a rigid breast compression paddle (RP) and reported large contribution of scatter signal from RP in the detector. However, in this work, flexible paddles (FPs) tilting from 0° to 10° will be studied using Monte Carlo simulations to analyse if the scatter distribution differs from RP geometries. After reproducing the Hologic Selenia Dimensions geometry (narrow angle) with two (homogeneous and heterogeneous) compressed breast phantoms, results illustrate that the scatter distribution recorded at the detector varies up to 22% between RP and FP geometries (depending on the location), mainly due to the decrease in thickness of the breast observed for FP. However, the relative contribution from the paddle itself (3-12% of the total scatter) remains approximately unchanged for both setups and their magnitude depends on the distance to the breast edge.

  11. Microscopie "CARS" (Coherent anti-Stokes Raman scattering). Génération du signal au voisinage d'interfaces et à l'intérieur d'une cavité Fabry-Perot.


    Gachet, D


    Coherent anti-Stokes Raman scattering (``CARS'') is a spectroscopic technique that gives access to intra-molecular vibrational information. It was first proposed as a contrast mechanism in microscopy in 1982, and was implemented under a convenient colinear configuration in 1999. Since then, the signal generation in CARS microscopy has been studied in the litterature on some simple configurations. In this PhD dissertation, we extend the CARS signal generation study in isotropic media using a f...

  12. v-Src-driven transformation is due to chromosome abnormalities but not Src-mediated growth signaling. (United States)

    Honda, Takuya; Morii, Mariko; Nakayama, Yuji; Suzuki, Ko; Yamaguchi, Noritaka; Yamaguchi, Naoto


    v-Src is the first identified oncogene product and has a strong tyrosine kinase activity. Much of the literature indicates that v-Src expression induces anchorage-independent and infinite cell proliferation through continuous stimulation of growth signaling by v-Src activity. Although all of v-Src-expressing cells are supposed to form transformed colonies, low frequencies of v-Src-induced colony formation have been observed so far. Using cells that exhibit high expression efficiencies of inducible v-Src, we show that v-Src expression causes cell-cycle arrest through p21 up-regulation despite ERK activation. v-Src expression also induces chromosome abnormalities and unexpected suppression of v-Src expression, leading to p21 down-regulation and ERK inactivation. Importantly, among v-Src-suppressed cells, only a limited number of cells gain the ability to re-proliferate and form transformed colonies. Our findings provide the first evidence that v-Src-driven transformation is attributed to chromosome abnormalities, but not continuous stimulation of growth signaling, possibly through stochastic genetic alterations.

  13. Modeling of very low frequency (VLF radio wave signal profile due to solar flares using the GEANT4 Monte Carlo simulation coupled with ionospheric chemistry

    Directory of Open Access Journals (Sweden)

    S. Palit


    Full Text Available X-ray photons emitted during solar flares cause ionization in the lower ionosphere (~60 to 100 km in excess of what is expected to occur due to a quiet sun. Very low frequency (VLF radio wave signals reflected from the D-region of the ionosphere are affected by this excess ionization. In this paper, we reproduce the deviation in VLF signal strength during solar flares by numerical modeling. We use GEANT4 Monte Carlo simulation code to compute the rate of ionization due to a M-class flare and a X-class flare. The output of the simulation is then used in a simplified ionospheric chemistry model to calculate the time variation of electron density at different altitudes in the D-region of the ionosphere. The resulting electron density variation profile is then self-consistently used in the LWPC code to obtain the time variation of the change in VLF signal. We did the modeling of the VLF signal along the NWC (Australia to IERC/ICSP (India propagation path and compared the results with observations. The agreement is found to be very satisfactory.

  14. Bone resorption deficiency affects tooth root development in RANKL mutant mice due to attenuated IGF-1 signaling in radicular odontoblasts. (United States)

    Huang, Hong; Wang, Jue; Zhang, Yan; Zhu, Guochun; Li, Yi-Ping; Ping, Ji; Chen, Wei


    The tooth root is essential for normal tooth physiological function. Studies on mice with mutations or targeted gene deletions revealed that osteoclasts (OCs) play an important role in tooth root development. However, knowledge on the cellular and molecular mechanism underlying how OCs mediate root formation is limited. During bone formation, growth factors (e.g. Insulin-like growth factor-1, IGF-1) liberated from bone matrix by osteoclastic bone resorption stimulate osteoblast differentiation. Thus, we hypothesize that OC-osteoblast coupling may also apply to OC-odontoblast coupling; therefore OCs may have a direct impact on odontoblast differentiation through the release of growth factor(s) from bone matrix, and consequently regulate tooth root formation. To test this hypothesis, we used a receptor activator of NF-κB ligand (RANKL) knockout mouse model in which OC differentiation and function was entirely blocked. We found that molar root formation and tooth eruption were defective in RANKL-/- mice. Disrupted elongation and disorganization of Hertwig's epithelial root sheath (HERS) was observed in RANKL-/- mice. Reduced expression of nuclear factor I C (NFIC), osterix, and dentin sialoprotein, markers essential for radicular (root) odontogenic cell differentiation indicated that odontoblast differentiation was disrupted in RANKL deficient mice likely contributing to the defect in root formation. Moreover, down-regulation of IGF/AKT/mTOR activity in odontoblast indicated that IGF signaling transduction in odontoblasts of the mutant mice was impaired. Treating odontoblast cells in vitro with conditioned medium from RANKL-/- OCs cultured on bone slices resulted in inhibition of odontoblast differentiation. Moreover, depletion of IGF-1 in bone resorption-conditioned medium (BRCM) from wild-type (WT) OC significantly compromised the ability of WT osteoclastic BRCM to induce odontoblast differentiation while addition of IGF-1 into RANKL-/- osteoclastic BRCM rescued

  15. Evidence of Spin Resonance Signal in Oxygen Free Superconducting CaFe0.88Co0.12AsF: An Inelastic Neutron Scattering Study (United States)

    Price, Stephen; Su, Yixi; Xiao, Yinguo; Adroja, Devashibhai T.; Guidi, Tatiana; Mittal, Ranjan; Nandi, Shibabrata; Matsuishi, Satoru; Hosono, Hideo; Brückel, Thomas


    The spin excitation spectrum of optimally doped superconducting CaFe0.88Co0.12AsF (Tc˜ 22 K) was studied by means of time-of-flight (ToF) inelastic neutron scattering experiments on a powder sample for temperatures above and below Tc and energies up to 15 meV. In the superconducting state, the spin resonance signal is observed as an enhancement of spectral weight of particle hole excitations of approximately 1.5 times relative to normal state excitations. The resonance energy ER˜ 7 meV scales to Tc via 3.7 kBTc which is in reasonable agreement to the scaling relation reported for other Fe-based compositions. For energies below 5 meV the spectrum of spin flip particle hole excitations in the superconducting state exhibits a strong reduction in spectral weight, indicating the opening of the spin gap. Nonetheless, a complete suppression of magnetic response cannot be observed. In contrast, the normal state spin excitations are not gapped and strongly two dimensional spin fluctuations persist up to temperatures at least as high as 150 K.

  16. Evolution of the Rayleigh scattering from mixed Ar/Kr clusters during their saturation with krypton atoms (United States)

    Zhvaniya, I. A.; Dzhidzhoev, M. S.; Balakin, A. V.; Kuzechkin, N. A.; Shkurinov, A. P.; Gordienko, V. M.


    The evolution of the Rayleigh scattering signal from mixed Ar/Kr clusters with variation in the partial Kr concentration in the initial gas mixture is investigated. An addition of krypton in small amounts to argon is found to cause an anomalously rapid increase in the Rayleigh scattering signal amplitude, which is due to a sharp increase in the size of clusters as a result of their saturation with krypton atoms. At a partial krypton concentration above 25% in the initial mixture, the scattering signal amplitude is stabilised because of the condensation saturation during the cluster formation.

  17. Neutron signal transfer analysis

    CERN Document Server

    Pleinert, H; Lehmann, E


    A new method called neutron signal transfer analysis has been developed for quantitative determination of hydrogenous distributions from neutron radiographic measurements. The technique is based on a model which describes the detector signal obtained in the measurement as a result of the action of three different mechanisms expressed by signal transfer functions. The explicit forms of the signal transfer functions are determined by Monte Carlo computer simulations and contain only the distribution as a variable. Therefore an unknown distribution can be determined from the detector signal by recursive iteration. This technique provides a simple and efficient tool for analysis of this type while also taking into account complex effects due to the energy dependency of neutron interaction and single and multiple scattering. Therefore this method provides an efficient tool for precise quantitative analysis using neutron radiography, as for example quantitative determination of moisture distributions in porous buil...

  18. Diffuse scattering

    Energy Technology Data Exchange (ETDEWEB)

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


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

  19. Seismic scatterers in the mid-lower mantle beneath Tonga-Fiji (United States)

    Kaneshima, Satoshi


    We analyze deep and intermediate-depth earthquakes at the Tonga-Fiji region in order to reveal the distribution of scattering objects in the mid-lower mantle. By array processing waveform data recorded at regional seismograph stations in the US, Alaska, and Japan, we investigate S-to-P scattering waves in the P coda, which arise from kilometer-scale chemically distinct objects in the mid-lower mantle beneath Tonga-Fiji. With ten scatterers previously reported by the author included, twenty-three mid-lower mantle scatterers have been detected below 900 km depth, while scatterers deeper than 1900 km have not been identified. Strong mid-lower mantle S-to-P scattering most frequently occurs at the scatterers located within a depth range between 1400 km and 1600 km. The number of scatterers decreases below 1600 km depth, and the deeper objects tend to be weaker. The scatterer distribution may reflect diminishing elastic anomalies of basaltic rocks with depth relative to the surrounding mantle rocks, which mineral physics has predicted to occur. The predominant occurrence of strong S-to-P scattering waves within a narrow depth range may reflect significant reduction of rigidity due to the ferro-elastic transformation of stishovite in basaltic rocks. Very large signals associated with mid-mantle scatterers are observed only for a small portion of the entire earthquake-array pairs. Such infrequent observations of large scattering signals, combined with quite large event-to-event differences in the scattering intensity for each scatterer, suggest both that the strong arrivals approximately represent ray theoretical S-to-P converted waves at objects with a plane geometry. The plane portions of the strong scatterers may often dip steeply, with the size exceeding 100 km. For a few strong scatterers, the range of receivers showing clear scattered waves varies substantially from earthquake-array pair to pair. Some of the scatterers are also observed at different arrays that have

  20. Perceptual consequences of different signal changes due to binaural noise reduction: do hearing loss and working memory capacity play a role? (United States)

    Neher, Tobias; Grimm, Giso; Hohmann, Volker


    In a previous study, ) investigated whether pure-tone average (PTA) hearing loss and working memory capacity (WMC) modulate benefit from different binaural noise reduction (NR) settings. Results showed that listeners with smaller WMC preferred strong over moderate NR even at the expense of poorer speech recognition due to greater speech distortion (SD), whereas listeners with larger WMC did not. To enable a better understanding of these findings, the main aims of the present study were (1) to explore the perceptual consequences of changes to the signal mixture, target speech, and background noise caused by binaural NR, and (2) to determine whether response to these changes varies with WMC and PTA. As in the previous study, four age-matched groups of elderly listeners (with N = 10 per group) characterized by either mild or moderate PTAs and either better or worse performance on a visual measure of WMC participated. Five processing conditions were tested, which were based on the previously used (binaural coherence-based) NR scheme designed to attenuate diffuse signal components at mid to high frequencies. The five conditions differed in terms of the type of processing that was applied (no NR, strong NR, or strong NR with restoration of the long-term stimulus spectrum) and in terms of whether the target speech and background noise were processed in the same manner or whether one signal was left unprocessed while the other signal was processed with the gains computed for the signal mixture. Comparison across these conditions allowed assessing the effects of changes in high-frequency audibility (HFA), SD, and noise attenuation and distortion (NAD). Outcome measures included a dual-task paradigm combining speech recognition with a visual reaction time (VRT) task as well as ratings of perceived effort and overall preference. All measurements were carried out using headphone simulations of a frontal target speaker in a busy cafeteria. Relative to no NR, strong NR was found

  1. Stray light analysis for the Thomson scattering diagnostic of the ETE Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Berni, L. A. [Instituto Nacional de Pesquisas Espaciais (INPE), Laboratorio Associado de Sensores e Materiais (LAS), 12.227-010 Sao Jose dos Campos, SP (Brazil); Albuquerque, B. F. C. [Instituto Nacional de Pesquisas Espaciais (INPE), Engenharia e Tecnologia Espaciais, Divisao de Eletronica Aeroespacial, 12.227-010 Sao Jose dos Campos, SP (Brazil)


    Thomson scattering is a well-established diagnostic for measuring local electron temperature and density in fusion plasma, but this technique is particularly difficult to implement due to stray light that can easily mask the scattered signal from plasma. To mitigate this problem in the multipoint Thomson scattering system implemented at the ETE (Experimento Tokamak Esferico) a detailed stray light analysis was performed. The diagnostic system was simulated in ZEMAX software and scattering profiles of the mechanical parts were measured in the laboratory in order to have near realistic results. From simulation, it was possible to identify the main points that contribute to the stray signals and changes in the dump were implemented reducing the stray light signals up to 60 times.

  2. Thomson Scattering

    NARCIS (Netherlands)

    Donne, A. J. H.


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

  3. Study of the mechanism for broadening of the spectrum of a low-frequency reverberation signal for sound scattering by near-surface inhomogeneities under conditions of intense wind waves (United States)

    Salin, B. M.; Kemarskaya, O. N.; Molchanov, P. A.; Salin, M. B.


    The paper considers the problem of backscattering of sound waves by near-surface volumetric inhomogeneities under conditions of intense wind waves. We calculate the expected share of the scattered signal spectrum based on the given wind-wave intensity and the depth distribution of volumetric inhomogeneities. For deep ocean conditions in the frequency range of 500-1000 Hz for a pulse duration of 10 s, we measure the levels and shape of the reverberation spectrum for time delays from 20 to 100 s. Comparison of the measured and calculated reverberation spectra has shown their good coincidence.

  4. Critical scattering

    Energy Technology Data Exchange (ETDEWEB)

    Stirling, W.G. [Liverpool Univ., Dep. of Physics, Liverpool (United Kingdom); Perry, S.C. [Keele Univ. (United Kingdom). Dept. of Physics


    We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO{sub 3} is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs.

  5. Analysis of Signal-to-Crosstalk Ratio Variations due to Four-Wave Mixing in Dense Wavelength Division Multiplexing Systems Implemented with Standard Single-Mode Fibers

    Directory of Open Access Journals (Sweden)

    Sait Eser KARLIK


    Full Text Available In this paper, variation of the signal-to-crosstalk ratio (SXR due to effects of four-wave mixing (FWM has been analyzed on center channels of 5-, 7-, 9-channel dense wavelength division multiplexing (DWDM systems implemented with G.652 standard single-mode fibers (SSMFs for 12.5 GHz, 25 GHz, 50 GHz and 100 GHz equal channel spacing values. Center channels on such systems are the most severely impacted channels by FWM. Therefore, results obtained are the worst-case values for the DWDM system performance and important for system design. Simulations have been performed for systems using three different commercially available SMFs having different design parameter values for chromatic dispersion, dispersion slope, nonlinearity coefficient and attenuation coefficient which are all in the scope of the G.652 Recommendation of Telecommunication Standardization Sector of International Telecommunication Union (ITU-T for SSMFs. In those simulations, under the impact of FWM, variation of SXR with variations in input powers, channel spacings and link lengths have been observed. Simulation results display the combined effect of the optical fiber and system design parameters on FWM performance of DWDM systems and give important clues for not only long-haul but also access network implementations of DWDM systems.

  6. Inversion assuming weak scattering

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Gerstoft, Peter; Mosegaard, Klaus


    due to the complex nature of the field. A method based on linear inversion is employed to infer information about the statistical properties of the scattering field from the obtained cross-spectral matrix. A synthetic example based on an active high-frequency sonar demonstrates that the proposed...

  7. Light scattering by soap films

    NARCIS (Netherlands)

    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

  8. Neutralino Inelastic Scattering with Subsequent Detection of Nuclear Gamma Rays


    Engel, J; Vogel, P


    We consider the potential benefits of searching for supersymmetric dark-matter through its inelastic excitation, via the "scalar current", of low-lying collective nuclear states in a detector. If such states live long enough so that the gamma radiation from their decay can be separated from the signal due to nuclear recoil, then background can be dramatically reduced. We show how the kinematics of neutralino-nucleus scattering is modified when the nucleus is excited and derive expressions for...

  9. Identification of scintillation signatures on GPS signals originating from plasma structures detected with EISCAT incoherent scatter radar along the same line of sight (United States)

    Forte, Biagio; Coleman, Chris; Skone, Susan; Häggström, Ingemar; Mitchell, Cathryn; Da Dalt, Federico; Panicciari, Tommaso; Kinrade, Joe; Bust, Gary


    Ionospheric scintillation originates from the scattering of electromagnetic waves through spatial gradients in the plasma density distribution, drifting across a given propagation direction. Ionospheric scintillation represents a disruptive manifestation of adverse space weather conditions through degradation of the reliability and continuity of satellite telecommunication and navigation systems and services (e.g., European Geostationary Navigation Overlay Service, EGNOS). The purpose of the experiment presented here was to determine the contribution of auroral ionization structures to GPS scintillation. European Incoherent Scatter (EISCAT) measurements were obtained along the same line of sight of a given GPS satellite observed from Tromso and followed by means of the EISCAT UHF radar to causally identify plasma structures that give rise to scintillation on the co-aligned GPS radio link. Large-scale structures associated with the poleward edge of the ionospheric trough, with auroral arcs in the nightside auroral oval and with particle precipitation at the onset of a substorm were indeed identified as responsible for enhanced phase scintillation at L band. For the first time it was observed that the observed large-scale structures did not cascade into smaller-scale structures, leading to enhanced phase scintillation without amplitude scintillation. More measurements and theory are necessary to understand the mechanism responsible for the inhibition of large-scale to small-scale energy cascade and to reproduce the observations. This aspect is fundamental to model the scattering of radio waves propagating through these ionization structures. New insights from this experiment allow a better characterization of the impact that space weather can have on satellite telecommunications and navigation services.

  10. Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Botto, D.J.; Pratt, R.H.


    The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A/sup -2/ based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required.

  11. Experimental Verification of a New Model Describing the Influence of Incomplete Signal Extinction Ratio on the Sensitivity Degradation due to Multiple Interferometric Crosstalk

    DEFF Research Database (Denmark)

    Liu, Fenghai; Rasmussen, Christian Jørgen; Pedersen, Rune Johan Skullerud


    analytical relations for crosstalk induced power penalties are derived taking the signal extinction ratio into account and excellent agreement with 10-Gb/s experiments is obtained. Both theory and experiment show the importance of the signal extinction ratio in connection with interferometric crosstalk....


    Energy Technology Data Exchange (ETDEWEB)

    Palliyaguru, Nipuni; McLaughlin, Maura [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Stinebring, Daniel [Department of Physics and Astronomy, Oberlin College, 110 North Professor Street, Oberlin, OH 44074 (United States); Demorest, Paul [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Jones, Glenn, E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [Department of Physics, Columbia University, New York, NY 10027 (United States)


    Light travel time changes due to gravitational waves (GWs) may be detected within the next decade through precision timing of millisecond pulsars. Removal of frequency-dependent interstellar medium (ISM) delays due to dispersion and scattering is a key issue in the detection process. Current timing algorithms routinely correct pulse times of arrival (TOAs) for time-variable delays due to cold plasma dispersion. However, none of the major pulsar timing groups correct for delays due to scattering from multi-path propagation in the ISM. Scattering introduces a frequency-dependent phase change in the signal that results in pulse broadening and arrival time delays. Any method to correct the TOA for interstellar propagation effects must be based on multi-frequency measurements that can effectively separate dispersion and scattering delay terms from frequency-independent perturbations such as those due to a GW. Cyclic spectroscopy, first described in an astronomical context by Demorest (2011), is a potentially powerful tool to assist in this multi-frequency decomposition. As a step toward a more comprehensive ISM propagation delay correction, we demonstrate through a simulation that we can accurately recover impulse response functions (IRFs), such as those that would be introduced by multi-path scattering, with a realistic signal-to-noise ratio (S/N). We demonstrate that timing precision is improved when scatter-corrected TOAs are used, under the assumptions of a high S/N and highly scattered signal. We also show that the effect of pulse-to-pulse “jitter” is not a serious problem for IRF reconstruction, at least for jitter levels comparable to those observed in several bright pulsars.

  13. SU-E-I-64: X-Ray Coherent Scatter Mammography Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, L R; MacDonald, C A [University at Albany, SUNY, Albany, NY (United States)


    Purpose: Conventional mammography has poor contrast between healthy and cancerous tissues due to the small difference in attenuation properties. Coherent scatter potentially provides more information because interference of coherently scattered radiation depends on the average intermolecular spacing, and can be used to characterize tissue types. However, typical coherent scatter analysis techniques are not compatible with rapid low dose screening modalities. Coherent scatter slot scan imaging is a novel imaging technique which provides new information with higher contrast. In this work a simulation was performed of coherent scatter slot scan imaging to assess its performance and provide system optimization. Methods: In coherent scatter imaging, the coherent scatter is exploited using a conventional slot scan mammography system with anti-scatter grids tilted at the characteristic angle of cancerous tissues. A Monte Carlo simulation was used to simulate the coherent scatter imaging. System optimization was performed across several parameters, including source voltage and filtration, tilt angle, source and grid distances, grid ratio, and shielding geometry. Results: The contrast was high and increased as the grid tilt angle was increased beyond the characteristic angle for the modeled carcinoma, and as the source voltage increased. Source filtration did not have a significant effect on contrast. Increasing grid ratio improved contrast at the expense of decreasing the signal to noise ratio (SNR). As the tumor size is decreased, additional shields to block the fat signal are necessary in order to detect the cancer signal. Conclusion: Coherent scatter analysis using a wide slot setup is promising as an enhancement for screening mammography. This work was supported by National Institutes of Health, # 7 R01EB009715.

  14. Development of general X-ray scattering model

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Joe, E-mail:; Wendt, Scott, E-mail: [Center for NDE, Iowa State University, Ames, IA 50011 (United States)


    X-ray scattering is a complex process made difficult to describe due to the effects of a complex energy spectrum interacting with a wide range of material types in complex geometry. The scattering is further complicated by the volume of material illuminated and the experimental configuration of the data acquisition. The importance of accounting for the key physics in scattering modeling is critical to the viability of the model. For example, scattering in the detector and the speed of the detector, as measured by the absorbed dose needed to produce a signal, are important in capturing undercut effects. Another example is the noise properties of the detectors are dependent on photon energy. We report on a semi-empirical treatment of x-ray scattering that includes a full energy treatment for a wide range of material types. We also include complex geometry effects that the part shape introduces. The treatment is based on experimental measurements using an energy dispersive germanium detector over energies from treatment is showing good results with experimental measurements of the scattering component agreeing with the model results to the 10% level over the range of x-ray energies and materials typical in industrial applications. Computation times for this model are in the 20 keV to 320 keV. Detector stripping routines for detector artifacts were developed. The computation time is in the range of a few minutes on a typical PC.

  15. 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)


    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.

  16. High signal in the adenohypophysis on T1-weighted images presumably due to manganese deposits in patients on long-term parenteral nutrition

    Energy Technology Data Exchange (ETDEWEB)

    Dietemann, J.L.; Diniz, R.L.F.C.; Reis, M. Jr.; Neugroschl, C.; Soehsten, S. von [Department of Radiology 2, University Hospital of Strasbourg (France); Reimund, J.M.; Baumann, R. [Department of Hepatogastroenterology, University Hospital of Strasbourg (France); Warter, J.M. [Department of Neurology, University Hospital of Strasbourg (France)


    Hypermanganesaemia is reported in patients on long-term parenteral nutrition. Deposition of manganese, giving high signal on T1-weighted images, may involve the basal ganglia. MRI in nine patients (mean age 51 years, range 31-75 years) on long-term parenteral nutrition (mean duration 30 months, range 6-126 months), demonstrated high signal in the anterior pituitary gland on T1-weighted sagittal and coronal images. The gland appeared normal on T2-weighted images. Signal intensity in the basal ganglia on T1-weighted images was increased in all patients. Endocrine assessment showed no significant abnormality. Neurological examination showed a mild parkinsonian movement disorder in one patient. Hypermanganaesemia was present in all nine (1.3-2.8 {mu}mol/l, mean 1.87 {mu}mol/l). The high signal in the anterior pituitary gland was probably related to deposition of paramagnetic substances, especially manganese. (orig.) With 2 figs., 1 tab., 17 refs.

  17. Assessing the osteoblast transcriptome in a model of enhanced bone formation due to constitutive G{sub s}–G protein signaling in osteoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Wattanachanya, Lalita, E-mail: [Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA (United States); Division of Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok (Thailand); Wang, Liping, E-mail: [Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA (United States); Millard, Susan M., E-mail: [Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA (United States); Lu, Wei-Dar, E-mail: [Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA (United States); O’Carroll, Dylan, E-mail: [Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA (United States); Hsiao, Edward C., E-mail: [Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Francisco, CA (United States); Conklin, Bruce R., E-mail: [Gladstone Institute of Cardiovascular Disease, San Francisco, CA (United States); Department of Medicine, University of California, San Francisco, CA (United States); Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA (United States); Nissenson, Robert A., E-mail: [Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA (United States)


    G protein-coupled receptor (GPCR) signaling in osteoblasts (OBs) is an important regulator of bone formation. We previously described a mouse model expressing Rs1, an engineered constitutively active G{sub s}-coupled GPCR, under the control of the 2.3 kb Col I promoter. These mice showed a dramatic age-dependent increase in trabecular bone of femurs. Here, we further evaluated the effects of enhanced G{sub s} signaling in OBs on intramembranous bone formation by examining calvariae of 1- and 9-week-old Col1(2.3)/Rs1 mice and characterized the in vivo gene expression specifically occurring in osteoblasts with activated G{sub s} G protein-coupled receptor signaling, at the cellular level rather than in a whole bone. Rs1 calvariae displayed a dramatic increase in bone volume with partial loss of cortical structure. By immunohistochemistry, Osterix was detected in cells throughout the inter-trabecular space while Osteocalcin was expressed predominantly in cells along bone surfaces, suggesting the role of paracrine mediators secreted from OBs driven by 2.3 kb Col I promoter could influence early OB commitment, differentiation, and/or proliferation. Gene expression analysis of calvarial OBs revealed that genes affected by Rs1 signaling include those encoding proteins important for cell differentiation, cytokines and growth factors, angiogenesis, coagulation, and energy metabolism. The set of G{sub s}-GPCRs and other GPCRs that may contribute to the observed skeletal phenotype and candidate paracrine mediators of the effect of G{sub s} signaling in OBs were also determined. Our results identify novel detailed in vivo cellular changes of the anabolic response of the skeleton to G{sub s} signaling in mature OBs. - Highlights: • OB expression of an engineered G{sub s}-coupled receptor dramatically increases bone mass. • We investigated the changes in gene expression in vivo in enhanced OB G{sub s} signaling. • Genes in cell cycle and transcription were increased in

  18. Scattering theory

    CERN Document Server

    Friedrich, Harald


    This corrected and updated second edition of "Scattering Theory" presents a concise and modern coverage of the subject. In the present treatment, special attention is given to the role played by the long-range behaviour of the projectile-target interaction, and a theory is developed, which is well suited to describe near-threshold bound and continuum states in realistic binary systems such as diatomic molecules or molecular ions. It is motivated by the fact that experimental advances have shifted and broadened the scope of applications where concepts from scattering theory are used, e.g. to the field of ultracold atoms and molecules, which has been experiencing enormous growth in recent years, largely triggered by the successful realization of Bose-Einstein condensates of dilute atomic gases in 1995. The book contains sections on special topics such as near-threshold quantization, quantum reflection, Feshbach resonances and the quantum description of scattering in two dimensions. The level of abstraction is k...

  19. Plasmonic Nanogap-Enhanced Raman Scattering with Nanoparticles. (United States)

    Nam, Jwa-Min; Oh, Jeong-Wook; Lee, Haemi; Suh, Yung Doug


    Plasmonic coupling-based electromagnetic field localization and enhancement are becoming increasingly important in chemistry, nanoscience, materials science, physics, and engineering over the past decade, generating a number of new concepts and applications. Among the plasmonically coupled nanostructures, metal nanostructures with nanogaps have been of special interest due to their ultrastrong electromagnetic fields and controllable optical properties that can be useful for a variety of signal enhancements such as surface-enhanced Raman scattering (SERS). The Raman scattering process is highly inefficient, with a very small cross-section, and Raman signals are often poorly reproducible, meaning that very strong, controllable SERS is needed to obtain reliable Raman signals with metallic nanostructures and thus open up new avenues for a variety of Raman-based applications. More specifically, plasmonically coupled metallic nanostructures with ultrasmall (∼1 nm or smaller) nanogaps can generate very strong and tunable electromagnetic fields that can generate strong SERS signals from Raman dyes in the gap, and plasmonic nanogap-enhanced Raman scattering can be defined as Raman signal enhancement from plasmonic nanogap particles with ∼1 nm gaps. However, these promising nanostructures with extraordinarily strong optical signals have shown limited use for practical applications, largely due to the lack of design principles, high-yield synthetic strategies with nanometer-level structural control and reproducibility, and systematic, reliable single-molecule/single-particle-level studies on their optical properties. All these are extremely important challenges because even small changes (plasmonic nanogaps can significantly affect the plasmon mode and signal intensity. In this Account, we examine and summarize recent breakthroughs and advances in plasmonic nanogap-enhanced Raman scattering with metal nanogap particles with respect to the design and synthesis of plasmonic

  20. Seamount acoustic scattering (United States)

    Boehlert, George W.

    The cover of the March 1 issue of Eos showed a time series of acoustic scattering above Southeast Hancock Seamount (29°48‧N, 178°05‧E) on July 17-18, 1984. In a comment on that cover Martin Hovland (Eos, August 2, p. 760) argued that gas or “other far reaching causes” may be involved in the observed acoustic signals. He favors a hypothesis that acoustic scattering observed above a seeping pockmark in the North Sea is a combination of bubbles, stable microbubbles, and pelagic organisms and infers that this may be a more general phenomenon and indeed plays a role in the attraction of organisms to seamounts

  1. Scatter correction for cone-beam CT in radiation therapy. (United States)

    Zhu, Lei; Xie, Yaoqin; Wang, Jing; Xing, Lei


    Cone-beam CT (CBCT) is being increasingly used in modern radiation therapy for patient setup and adaptive replanning. However, due to the large volume of x-ray illumination, scatter becomes a rather serious problem and is considered as one of the fundamental limitations of CBCT image quality. Many scatter correction algorithms have been proposed in literature, while a standard practical solution still remains elusive. In radiation therapy, the same patient is scanned repetitively during a course of treatment, a natural question to ask is whether one can obtain the scatter distribution on the first day of treatment and then use the data for scatter correction in the subsequent scans on different days. To realize this scatter removal scheme, two technical pieces must be in place: (i) A strategy to obtain the scatter distribution in on-board CBCT imaging and (ii) a method to spatially match a prior scatter distribution with the on-treatment CBCT projection data for scatter subtraction. In this work, simple solutions to the two problems are provided. A partially blocked CBCT is used to extract the scatter distribution. The x-ray beam blocker has a strip pattern, such that partial volume can still be accurately reconstructed and the whole-field scatter distribution can be estimated from the detected signals in the shadow regions using interpolation/extrapolation. In the subsequent scans, the patient transformation is determined using a rigid registration of the conventional CBCT and the prior partial CBCT. From the derived patient transformation, the measured scatter is then modified to adapt the new on-treatment patient geometry for scatter correction. The proposed method is evaluated using physical experiments on a clinical CBCT system. On the Catphan 600 phantom, the errors in Hounsfield unit (HU) in the selected regions of interest are reduced from about 350 to below 50 HU; on an anthropomorphic phantom, the error is reduced from 15.7% to 5.4%. The proposed method

  2. Quantum effets in nonresonant X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Slowik, Jan Malte


    Due to their versatile properties, X rays are a unique tool to investigate the structure and dynamics of matter. X-ray scattering is the fundamental principle of many imaging techniques. Examples are X-ray crystallography, which recently celebrated one hundred years and is currently the leading method in structure determination of proteins, as well as X-ray phase contrast imaging (PCI), which is an imaging technique with countless applications in biology, medicine, etc. The technological development of X-ray free electron lasers (XFEL) has brought X-ray imaging at the edge of a new scientific revolution. XFELs offer ultrashort X-ray pulses with unprecedented high X-ray fluence and excellent spatial coherence properties. These properties make them an outstanding radiation source for X-ray scattering experiments, providing ultrafast temporal resolution as well as atomic spatial resolution. However, the radiation-matter interaction in XFEL experiments also advances into a novel regime. This demands a sound theoretical fundament to describe and explore the new experimental possibilities. This dissertation is dedicated to the theoretical study of nonresonant X-ray scattering. As the first topic, I consider the near-field imaging by propagation based X-ray phase contrast imaging (PCI). I devise a novel theory of PCI, in which radiation and matter are quantized. Remarkably, the crucial interference term automatically excludes contributions from inelastic scattering. This explains the success of the classical description thus far. The second topic of the thesis is the X-ray imaging of coherent electronic motion, where quantum effects become particularly apparent. The electron density of coherent electronic wave packets - important in charge transfer and bond breaking - varies in time, typically on femto- or attosecond time scales. In the near future, XFELs are envisaged to provide attosecond X-ray pulses, opening the possibility for time-resolved ultrafast X-ray scattering

  3. Low-Dose and Scatter-Free Cone-Beam CT Imaging Using a Stationary Beam Blocker in a Single Scan: Phantom Studies

    Directory of Open Access Journals (Sweden)

    Xue Dong


    Full Text Available Excessive imaging dose from repeated scans and poor image quality mainly due to scatter contamination are the two bottlenecks of cone-beam CT (CBCT imaging. Compressed sensing (CS reconstruction algorithms show promises in recovering faithful signals from low-dose projection data but do not serve well the needs of accurate CBCT imaging if effective scatter correction is not in place. Scatter can be accurately measured and removed using measurement-based methods. However, these approaches are considered unpractical in the conventional FDK reconstruction, due to the inevitable primary loss for scatter measurement. We combine measurement-based scatter correction and CS-based iterative reconstruction to generate scatter-free images from low-dose projections. We distribute blocked areas on the detector where primary signals are considered redundant in a full scan. Scatter distribution is estimated by interpolating/extrapolating measured scatter samples inside blocked areas. CS-based iterative reconstruction is finally carried out on the undersampled data to obtain scatter-free and low-dose CBCT images. With only 25% of conventional full-scan dose, our method reduces the average CT number error from 250 HU to 24 HU and increases the contrast by a factor of 2.1 on Catphan 600 phantom. On an anthropomorphic head phantom, the average CT number error is reduced from 224 HU to 10 HU in the central uniform area.

  4. Disruption of TLR3 signaling due to cleavage of TRIF by the hepatitis A virus protease-polymerase processing intermediate, 3CD.

    Directory of Open Access Journals (Sweden)

    Lin Qu


    Full Text Available Toll-like receptor 3 (TLR3 and cytosolic RIG-I-like helicases (RIG-I and MDA5 sense viral RNAs and activate innate immune signaling pathways that induce expression of interferon (IFN through specific adaptor proteins, TIR domain-containing adaptor inducing interferon-β (TRIF, and mitochondrial antiviral signaling protein (MAVS, respectively. Previously, we demonstrated that hepatitis A virus (HAV, a unique hepatotropic human picornavirus, disrupts RIG-I/MDA5 signaling by targeting MAVS for cleavage by 3ABC, a precursor of the sole HAV protease, 3C(pro, that is derived by auto-processing of the P3 (3ABCD segment of the viral polyprotein. Here, we show that HAV also disrupts TLR3 signaling, inhibiting poly(I:C-stimulated dimerization of IFN regulatory factor 3 (IRF-3, IRF-3 translocation to the nucleus, and IFN-β promoter activation, by targeting TRIF for degradation by a distinct 3ABCD processing intermediate, the 3CD protease-polymerase precursor. TRIF is proteolytically cleaved by 3CD, but not by the mature 3C(pro protease or the 3ABC precursor that degrades MAVS. 3CD-mediated degradation of TRIF depends on both the cysteine protease activity of 3C(pro and downstream 3D(pol sequence, but not 3D(pol polymerase activity. Cleavage occurs at two non-canonical 3C(pro recognition sequences in TRIF, and involves a hierarchical process in which primary cleavage at Gln-554 is a prerequisite for scission at Gln-190. The results of mutational studies indicate that 3D(pol sequence modulates the substrate specificity of the upstream 3C(pro protease when fused to it in cis in 3CD, allowing 3CD to target cleavage sites not normally recognized by 3C(pro. HAV thus disrupts both RIG-I/MDA5 and TLR3 signaling pathways through cleavage of essential adaptor proteins by two distinct protease precursors derived from the common 3ABCD polyprotein processing intermediate.

  5. Nonlinear coda wave analysis of hysteretic elastic behavior in strongly scattering media (United States)

    Ouarabi, M. Ait; Boubenider, F.; Gliozzi, A. S.; Scalerandi, M.


    Strongly scattering elastic media, such as consolidated granular materials, respond to ultrasonic pulse excitations with a long response signal with peculiar properties. The portion of the signal at late times, termed coda, is due to multiple scattering. It contains information about the elastic properties of the material, and it has been proven to be very sensitive to small variations in the modulus. Here we propose a technique based on a nonlinear analysis of the coda of a signal, which might be applied to quantify the nonlinear elastic response in consolidated granular media exhibiting a hysteretic elastic behavior. The method proposed allows for an intrinsic definition of the reference signal which is normally needed for applying coda-based methods.

  6. Light Scattering Spectroscopy: From Elastic to Inelastic (United States)

    Perelman, Lev T.; Modell, Mark D.; Vitkin, Edward; Hanlon, Eugene B.

    This chapter reviews light scattering spectroscopic techniques in which coherent effects are critical because they define the structure of the spectrum. In the case of elastic light scattering spectroscopy, the targets themselves, such as aerosol particles in environmental science or cells and subcellular organelles in biomedical applications, play the role of microscopic optical resonators. In the case of inelastic light scattering spectroscopy or Raman spectroscopy, the spectrum is created due to light scattering from vibrations in molecules or optical phonons in solids. We will show that light scattering spectroscopic techniques, both elastic and inelastic, are emerging as very useful tools in material and environmental science and in biomedicine.

  7. Experimental elucidation: microscopic mechanism of resonant X-ray scattering in manganite films

    CERN Document Server

    Ohsumi, H; Kiyama, T


    Resonant X-ray scattering experiments have been performed on perovskite manganite La sub 0 sub . sub 5 Sr sub 0 sub . sub 5 MnO sub 3 thin films, which are grown on three distinct perovskite with a coherent epitaxial strain and have a forced ferro-type orbital ordering of Mn 3d orbitals. Using an interference technique, we have successfully observed the resonant X-ray scattering signal from the system having the ferro-type orbital ordering and also revealed the energy scheme of Mn 4p bands. For the forced ferro-type orbital ordering system, the present results evidence that the resonant X-ray scattering signal originates from the band structure effect due to the Jahn-Teller distortion of a MnO sub 6 octahedron, and not from the Coulomb interaction between 3d and 4p electrons. (author)

  8. Analysis of second order harmonic distortion due to transmitter non-linearity and chromatic and modal dispersion of optical OFDM SSB modulated signals in SMF-MMF fiber links (United States)

    Patel, Dhananjay; Singh, Vinay Kumar; Dalal, U. D.


    Single mode fibers (SMF) are typically used in Wide Area Networks (WAN), Metropolitan Area Networks (MAN) and also find applications in Radio over Fiber (RoF) architectures supporting data transmission in Fiber to the Home (FTTH), Remote Antenna Units (RAUs), in-building networks etc. Multi-mode fibers (MMFs) with low cost, ease of installation and low maintenance are predominantly (85-90%) deployed in-building networks providing data access in local area networks (LANs). The transmission of millimeter wave signals through the SMF in WAN and MAN, along with the reuse of MMF in-building networks will not levy fiber reinstallation cost. The transmission of the millimeter waves experiences signal impairments due to the transmitter non-linearity and modal dispersion of the MMF. The MMF exhibiting large modal dispersion limits the bandwidth-length product of the fiber. The second and higher-order harmonics present in the optical signal fall within the system bandwidth. This causes degradation in the received signal and an unwanted radiation of power at the RAU. The power of these harmonics is proportional to the non-linearity of the transmitter and the modal dispersion of the MMF and should be maintained below the standard values as per the international norms. In this paper, a mathematical model is developed for Second-order Harmonic Distortion (HD2) generated due to non-linearity of the transmitter and chromatic-modal dispersion of the SMF-MMF optic link. This is also verified using a software simulation. The model consists of a Mach Zehnder Modulator (MZM) that generates two m-QAM OFDM Single Sideband (SSB) signals based on phase shift of the hybrid coupler (90° and 120°). Our results show that the SSB signal with 120° hybrid coupler has suppresses the higher-order harmonics and makes the system more robust against the HD2 in the SMF-MMF optic link.

  9. Monte Carlo simulations of a novel coherent scatter materials discrimination system (United States)

    Hassan, Laila; Starr-Baier, Sean; MacDonald, C. A.; Petruccelli, Jonathan C.


    X-ray coherent scatter imaging has the potential to improve the detection of liquid and powder materials of concern in security screening. While x-ray attenuation is dependent on atomic number, coherent scatter is highly dependent on the characteristic angle for the target material, and thus offers an additional discrimination. Conventional coherent scatter analysis requires pixel-by-pixel scanning, and so could be prohibitively slow for security applications. A novel slot scan system has been developed to provide rapid imaging of the coherent scatter at selected angles of interest, simultaneously with the conventional absorption images. Prior experimental results showed promising capability. In this work, Monte Carlo simulations were performed to assess discrimination capability and provide system optimization. Simulation analysis performed using the measured ring profiles for an array of powders and liquids, including water, ethanol and peroxide. For example, simulations yielded a signal-to-background ratio of 1.63+/-0.08 for a sample consisting of two 10 mm diameter vials, one containing ethanol (signal) and one water (background). This high SBR value is due to the high angular separation of the coherent scatter between the two liquids. The results indicate that the addition of coherent scatter information to single or dual energy attenuation images improves the discrimination of materials of interest.


    African Journals Online (AJOL)

    Dr A.B.Ahmed

    ISSN 1597-6343. Numerical Solutions of Some Parametric Effects Due to Electromagnetic Wave. Scattering by an Infinite Circular Cylinder. NUMERICAL SOLUTIONS OF SOME PARAMETRIC EFFECTS DUE. TO ELECTROMAGNETIC WAVE SCATTERING BY AN INFINITE. CIRCULAR CYLINDER. *1 Suleiman A. B. and 1 ...

  11. Biological cell classification by multiangle light scattering (United States)

    Salzman, G.C.; Crowell, J.M.; Mullaney, P.F.


    The specification is directed to an apparatus and method for detecting light scattering from a biological cell. Light, preferably from a coherent source of radiation, intercepts an individual biological cell in a stream of cells passing through the beam. Light scattered from the cell is detected at a selected number of angles between 0 and 90/sup 0/ to the longitudinal axis of the beam with a circular array of light responsive elements which produce signals representative of the intensity of light incident thereon. Signals from the elements are processed to determine the light-scattering pattern of the cell and therefrom its identity.

  12. A Simple Scatter Reduction Method in Cone-Beam Computed Tomography for Dental and Maxillofacial Applications Based on Monte Carlo Simulation

    Directory of Open Access Journals (Sweden)

    Chalinee Thanasupsombat


    Full Text Available The quality of images obtained from cone-beam computed tomography (CBCT is important in diagnosis and treatment planning for dental and maxillofacial applications. However, X-ray scattering inside a human head is one of the main factors that cause a drop in image quality, especially in the CBCT system with a wide-angle cone-beam X-ray source and a large area detector. In this study, the X-ray scattering distribution within a standard head phantom was estimated using the Monte Carlo method based on Geant4. Due to small variation of low-frequency scattering signals, the scattering signals from the head phantom can be represented as the simple predetermined scattering signals from a patient’s head and subtracted the projection data for scatter reduction. The results showed higher contrast and less cupping artifacts on the reconstructed images of the head phantom and real patients. Furthermore, the same simulated scattering signals can also be applied to process with higher-resolution projection data.

  13. Optical scattering measurement and analysis

    CERN Document Server

    Stover, John C


    Newly included are scatter models for pits and particles as well as the use of wafer scanners to locate and size isolated surface features. New sections cover the multimillion-dollar wafer scanner business, establishing that microroughness is the noise, not the signal, in these systems. Scatter measurements, now routinely used to determine whether small-surface features are pits or particles and inspiring new technology that provides information on particle material, are also discussed. These new capabilities are now supported by a series of international standards, and a new chapter reviews t

  14. On scattered subword complexity

    CERN Document Server

    Kása, Zoltán


    Special scattered subwords, in which the gaps are of length from a given set, are defined. The scattered subword complexity, which is the number of such scattered subwords, is computed for rainbow words.

  15. Scatter corrections for cone beam optical CT

    Energy Technology Data Exchange (ETDEWEB)

    Olding, Tim; Holmes, Oliver [Department of Physics, Queen' s University (United Kingdom); Schreiner, L John [Medical Physics Department, Cancer Centre of Southeastern Ontario (Canada)], E-mail:


    Cone beam optical computed tomography (OptCT) employing the VISTA scanner (Modus Medical, London, ON) has been shown to have significant promise for fast, three dimensional imaging of polymer gel dosimeters. One distinct challenge with this approach arises from the combination of the cone beam geometry, a diffuse light source, and the scattering polymer gel media, which all contribute scatter signal that perturbs the accuracy of the scanner. Beam stop array (BSA), beam pass array (BPA) and anti-scatter polarizer correction methodologies have been employed to remove scatter signal from OptCT data. These approaches are investigated through the use of well-characterized phantom scattering solutions and irradiated polymer gel dosimeters. BSA corrected scatter solutions show good agreement in attenuation coefficient with the optically absorbing dye solutions, with considerable reduction of scatter-induced cupping artifact at high scattering concentrations. The application of BSA scatter corrections to a polymer gel dosimeter lead to an overall improvement in the number of pixel satisfying the (3%, 3mm) gamma value criteria from 7.8% to 0.15%.

  16. Non-labeled lensless micro-endoscopic approach for cellular imaging through highly scattering media. (United States)

    Wagner, Omer; Pandya, Aditya; Chemla, Yoav; Pinhas, Hadar; Schelkanova, Irina; Shahmoon, Asaf; Mandel, Yossi; Douplik, Alexandre; Zalevsky, Zeev


    We describe an imaging approach based on an optical setup made up of a miniature, lensless, minimally invasive endoscope scanning a sample and matching post processing techniques that enable enhanced imaging capabilities. The two main scopes of this article are that this approach enables imaging beyond highly scattering medium and increases the resolution and signal to noise levels reaching single cell imaging. Our approach has more advantages over ordinary endoscope setups and other imaging techniques. It is not mechanically limited by a lens, the stable but flexible fiber can acquire images over long time periods (unlike current imaging methods such as OCT etc.), and the imaging can be obtained at a certain working distance above the surface, without interference to the imaged object. Fast overlapping scans enlarge the region of interest, enhance signal to noise levels and can also accommodate post-processing, super-resolution algorithms. Here we present that due to the setup properties, the overlapping scans also lead to dramatic enhancement of non-scattered signal to scattered noise. This enables imaging through highly scattering medium. We discuss results obtained from in vitro investigation of weak signals of ARPE cells, rat retina, and scattered signals from polydimethylsiloxane (PDMS) microchannels filled with hemoglobin and covered by intralipids consequently mimicking blood capillaries and the epidermis of human skin. The development of minimally invasive procedures and methodologies for imaging through scattering medium such as tissues can vastly enhance biomedical diagnostic capabilities for imaging internal organs. We thereby propose that our method may be used for such tasks in vivo. © 2018 The Author(s).

  17. Putrescine protects hulless barley from damage due to UV-B stress via H2S- and H2O2-mediated signaling pathways. (United States)

    Li, Qien; Wang, Zhaofeng; Zhao, Yanning; Zhang, Xiaochen; Zhang, Shuaijun; Bo, Letao; Wang, Yao; Ding, Yingfeng; An, Lizhe


    In hulless barley, H 2 S mediated increases in H 2 O 2 induced by putrescine, and their interaction enhanced tolerance to UV-B by maintaining redox homeostasis and promoting the accumulation of UV-absorbing compounds. This study investigated the possible relationship between putrescence (Put), hydrogen sulfide (H2S) and hydrogen peroxide (H2O2) as well as the underlying mechanism of their interaction in reducing UV-B induced damage. UV-B radiation increased electrolyte leakage (EL) and the levels of malondialdehyde (MDA) and UV-absorbing compounds but reduced antioxidant enzyme activities and glutathione (GSH) and ascorbic acid (AsA) contents. Exogenous application of Put, H2S or H2O2 reduced some of the above-mentioned negative effects, but were enhanced by the addition of Put, H2S and H2O2 inhibitors. Moreover, the protective effect of Put against UV-B radiation-induced damage to hulless barley was diminished by DL-propargylglycine (PAG, a H2S biosynthesis inhibitor), hydroxylamine (HT, a H2S scavenger), diphenylene iodonium (DPI, a PM-NADPH oxidase inhibitor) and dimethylthiourea (DMTU, a ROS scavenger), and the effect of Put on H2O2 accumulation was abolished by HT. Taken together, as the downstream component of the Put signaling pathway, H2S mediated H2O2 accumulation, and H2O2 induced the accumulation of UV-absorbing compounds and maintained redox homeostasis under UV-B stress, thereby increasing the tolerance of hulless barley seedlings to UV-B stress.

  18. X-Ray Scatter Correction on Soft Tissue Images for Portable Cone Beam CT

    Directory of Open Access Journals (Sweden)

    Sorapong Aootaphao


    Full Text Available Soft tissue images from portable cone beam computed tomography (CBCT scanners can be used for diagnosis and detection of tumor, cancer, intracerebral hemorrhage, and so forth. Due to large field of view, X-ray scattering which is the main cause of artifacts degrades image quality, such as cupping artifacts, CT number inaccuracy, and low contrast, especially on soft tissue images. In this work, we propose the X-ray scatter correction method for improving soft tissue images. The X-ray scatter correction scheme to estimate X-ray scatter signals is based on the deconvolution technique using the maximum likelihood estimation maximization (MLEM method. The scatter kernels are obtained by simulating the PMMA sheet on the Monte Carlo simulation (MCS software. In the experiment, we used the QRM phantom to quantitatively compare with fan-beam CT (FBCT data in terms of CT number values, contrast to noise ratio, cupping artifacts, and low contrast detectability. Moreover, the PH3 angiography phantom was also used to mimic human soft tissues in the brain. The reconstructed images with our proposed scatter correction show significant improvement on image quality. Thus the proposed scatter correction technique has high potential to detect soft tissues in the brain.

  19. Bidirectional optical scattering facility (United States)

    Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI)The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from a...

  20. Shifts in the Gut Microbiota Composition Due to Depleted Bone Marrow Beta Adrenergic Signaling Are Associated with Suppressed Inflammatory Transcriptional Networks in the Mouse Colon. (United States)

    Yang, Tao; Ahmari, Niousha; Schmidt, Jordan T; Redler, Ty; Arocha, Rebeca; Pacholec, Kevin; Magee, Kacy L; Malphurs, Wendi; Owen, Jennifer L; Krane, Gregory A; Li, Eric; Wang, Gary P; Vickroy, Thomas W; Raizada, Mohan K; Martyniuk, Christopher J; Zubcevic, Jasenka


    chimera colon. Thus, sympathetic regulation of BM-derived immune cells plays a significant role in modifying inflammatory networks in the colon and the gut microbiota composition. To our knowledge, this study is the first to suggest a key role of BM b1/2-ARs signaling in host-microbiota interactions, and reveals specific molecular mechanisms that may lead to generation of novel anti-inflammatory treatments for many immune and autonomic diseases as well as gut dysbiosis across the board.

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

    Mullen, Linda; Alley, Derek; Cochenour, Brandon


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

  2. Kaons and antiproton-nucleus scattering

    CERN Document Server

    Haque, S; Rahman, S N


    The elastic scattering of Kaons and antiprotons from several nuclei is studied in the framework of the generalized diffraction model due to Frahn and Venter. The systematics of reaction cross section and the standard nuclear radius, as given by the model, are discussed. The parameters obtained from the elastic scattering analyses are used, without any adjustment, to reproduce some inelastic scattering angular distributions and the corresponding deformation parameters are determined.

  3. Chitosan nanofiber scaffold improves bone healing via stimulating trabecular bone production due to upregulation of the Runx2/osteocalcin/alkaline phosphatase signaling pathway. (United States)

    Ho, Ming-Hua; Yao, Chih-Jung; Liao, Mei-Hsiu; Lin, Pei-I; Liu, Shing-Hwa; Chen, Ruei-Ming


    Osteoblasts play critical roles in bone formation. Our previous study showed that chitosan nanofibers can stimulate osteoblast proliferation and maturation. This translational study used an animal model of bone defects to evaluate the effects of chitosan nanofiber scaffolds on bone healing and the possible mechanisms. In this study, we produced uniform chitosan nanofibers with fiber diameters of approximately 200 nm. A bone defect was surgically created in the proximal femurs of male C57LB/6 mice, and then the left femur was implanted with chitosan nanofiber scaffolds for 21 days and compared with the right femur, which served as a control. Histological analyses revealed that implantation of chitosan nanofiber scaffolds did not lead to hepatotoxicity or nephrotoxicity. Instead, imaging analyses by X-ray transmission and microcomputed tomography showed that implantation of chitosan nanofiber scaffolds improved bone healing compared with the control group. In parallel, microcomputed tomography and bone histomorphometric assays further demonstrated augmentation of the production of new trabecular bone in the chitosan nanofiber-treated group. Furthermore, implantation of chitosan nanofiber scaffolds led to a significant increase in the trabecular bone thickness but a reduction in the trabecular parameter factor. As to the mechanisms, analysis by confocal microscopy showed that implantation of chitosan nanofiber scaffolds increased levels of Runt-related transcription factor 2 (Runx2), a key transcription factor that regulates osteogenesis, in the bone defect sites. Successively, amounts of alkaline phosphatase and osteocalcin, two typical biomarkers that can simulate bone maturation, were augmented following implantation of chitosan nanofiber scaffolds. Taken together, this translational study showed a beneficial effect of chitosan nanofiber scaffolds on bone healing through stimulating trabecular bone production due to upregulation of Runx2-mediated alkaline

  4. Chitosan nanofiber scaffold improves bone healing via stimulating trabecular bone production due to upregulation of the Runx2/osteocalcin/alkaline phosphatase signaling pathway (United States)

    Ho, Ming-Hua; Yao, Chih-Jung; Liao, Mei-Hsiu; Lin, Pei-I; Liu, Shing-Hwa; Chen, Ruei-Ming


    Osteoblasts play critical roles in bone formation. Our previous study showed that chitosan nanofibers can stimulate osteoblast proliferation and maturation. This translational study used an animal model of bone defects to evaluate the effects of chitosan nanofiber scaffolds on bone healing and the possible mechanisms. In this study, we produced uniform chitosan nanofibers with fiber diameters of approximately 200 nm. A bone defect was surgically created in the proximal femurs of male C57LB/6 mice, and then the left femur was implanted with chitosan nanofiber scaffolds for 21 days and compared with the right femur, which served as a control. Histological analyses revealed that implantation of chitosan nanofiber scaffolds did not lead to hepatotoxicity or nephrotoxicity. Instead, imaging analyses by X-ray transmission and microcomputed tomography showed that implantation of chitosan nanofiber scaffolds improved bone healing compared with the control group. In parallel, microcomputed tomography and bone histomorphometric assays further demonstrated augmentation of the production of new trabecular bone in the chitosan nanofiber-treated group. Furthermore, implantation of chitosan nanofiber scaffolds led to a significant increase in the trabecular bone thickness but a reduction in the trabecular parameter factor. As to the mechanisms, analysis by confocal microscopy showed that implantation of chitosan nanofiber scaffolds increased levels of Runt-related transcription factor 2 (Runx2), a key transcription factor that regulates osteogenesis, in the bone defect sites. Successively, amounts of alkaline phosphatase and osteocalcin, two typical biomarkers that can simulate bone maturation, were augmented following implantation of chitosan nanofiber scaffolds. Taken together, this translational study showed a beneficial effect of chitosan nanofiber scaffolds on bone healing through stimulating trabecular bone production due to upregulation of Runx2-mediated alkaline

  5. Determination of optical scattering properties of highly-scattering media in optical coherence tomography images

    DEFF Research Database (Denmark)

    Levitz, D.; Thrane, L.; Frosz, Michael Henoch


    We developed a new algorithm that fits optical coherence tomography (OCT) signals as a function of depth to a general theoretical OCT model which takes into account multiple scattering effects. With use of this algorithm, it was possible to extract both the scattering coefficient and anisotropy...

  6. Modeling of Brillouin scattering in long-distance fiber optic links with bidirectional optical amplifiers (United States)

    Salwik, Karol; Śliwczyński, Łukasz; Krehlik, Przemysław


    For the dissemination of precise signals from atomic clocks (like e.g. cesium clocks/fountains, H-masers or optical clocks) an optical link operating bi-directionally over the same fiber is essential. In such a link stimulated Brillouin scattering is one of the non-linear effects that may reduce the power of forward optical signal and convert it into the noise that propagates in the backward direction. In the link that uses a number of bi-directional optical amplifiers, the conditions that trigger the Brillouin scattering process may occur relatively easily because of large effective length for the scattering process. Thus in the design phase of the link, checking of the conditions for Brillouin scattering should be a part of optimization procedure (i.e. optimizing bi-directional amplifiers gains). In the paper we consider the mathematical model of the stimulated Brillouin scattering in the long distance, fiber optic links with multiple bidirectional optical amplifiers. The model was implemented in Matlab and consists of the coupled differential equations describing the propagation of pump and scattered signals that develops due to spontaneous scattering. The presence of bi-directional optical amplifiers is modeled as point-like discontinuity of the α parameter that is used to represent the attenuation of the fiber. These discontinuities create an extra level of difficulty when numerically solving the coupled equations (the problem is stiff) so special algorithm is presented that iteratively searches for the solution. The obtained results were compared with the measurements of the real link to confirm the correctness of the solution.

  7. Elastic scattering, polarization and absorption of relativistic antiprotons on nuclei (United States)

    Larionov, A. B.; Lenske, H.


    We perform Glauber model calculations of the antiproton-nucleus elastic and quasielastic scattering and absorption in the beam momentum range ∼ 0.5 ÷ 10 GeV / c. A good agreement of our calculations with available LEAR data and with earlier Glauber model studies of the p bar A elastic scattering allows us to make predictions at the beam momenta of ∼10 GeV/c, i.e. at the regime of the PANDA experiment at FAIR. The comparison with the proton-nucleus elastic scattering cross sections shows that the diffractive minima are much deeper in the p bar A case due to smaller absolute value of the ratio of the real-to-imaginary part of the elementary elastic amplitude. Significant polarization signal for p bar A elastic scattering at 10 GeV/c is expected. We have also revealed a strong dependence of the p bar A absorption cross section on the slope parameter of the transverse momentum dependence of the elementary p bar N amplitude. The p bar A optical potential is discussed.

  8. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)


    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  9. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)


    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  10. Spontaneous Brillouin scattering in a microdroplet (United States)

    Ching, S. C.; Leung, P. T.; Young, K.


    Spontaneous Brillouin scattering in a micrometer-sized liquid droplet is analyzed from first principles, using the spherical-wave normal-mode basis. Instead of the conservation of linear momentum, this interaction is governed by a selection rule due to the conservation of angular momentum. The Brillouin spectrum is then calculated, both for observation at a given angle and for the sum over all angles, and compared with scattering in a bulk medium. Special attention is paid to the case where the incident and scattered radiation fall on an electromagnetic resonance of the droplet. The analysis lays the foundation for formulating stimulated Brillouin scattering in the same system.

  11. Enhanced Simultaneous Distributed Strain and Temperature Fiber Sensor Employing Spontaneous Brillouin Scattering and Optical Pulse Coding


    Soto, M A; Bolognini, G.; Di Pasquale, F.


    In this work, we propose the use of optical pulse coding techniques for simultaneous strain and temperature sensing based on spontaneous Brillouin scattering. Optical pulse coding provides a significant receiver signal-to-noise ratio enhancement, allowing for accurate Brillouin intensity and frequency shift measurements at low peak power levels. Due to the cross-sensitivity of these two parameters on both temperature and strain, optical pulse coding improves the temperature and strain resolut...

  12. A due

    DEFF Research Database (Denmark)

    to acknowledge the excellence of these two scholars by a double Festschrift, "A due". Both have been working at the Music Department of the University of Copenhagen and have collaborated with The Royal Library on various projects. This publication contains contributions from 44 colleagues, who thus - in topics...

  13. Recoil corrections in antikaon-deuteron scattering

    Directory of Open Access Journals (Sweden)

    Mai Maxim


    Full Text Available Using the non-relativistic effective field theory approach for K−d scattering, it is demonstrated that a systematic perturbative expansion of the recoil corrections in the parameter ξ = MK/mN is possible in spite of the fact that K−d scattering at low energies is inherently non-perturbative due to the large values of the K̄N scattering lengths. The first order correction to the K−d scattering length due to single insertion of the retardation term in the multiple-scattering series is calculated. The recoil effect turns out to be reasonably small even at the physical value of MK/mN ≃ 0:5.

  14. Resonances in pi-K scattering

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, David J. [Old Dominion University, Norfolk, VA


    We have obtained clear signals of resonances in coupled-channel pi K - eta K scattering. Using distillation and a large basis of operators we are able to extract a precise spectrum of energy levels using the variational method. These energies are analysed using inelastic extensions of the Luescher method to obtain scattering amplitudes that clearly describe S, P and D wave resonances, corresponding to the physical K_0^*(1430), the K^*(892) and the K_2^*(1430).

  15. Lectures in scattering theory

    CERN Document Server

    Sitenko, A G


    Lectures in Scattering Theory discusses problems in quantum mechanics and the principles of the non-relativistic theory of potential scattering. This book describes in detail the properties of the scattering matrix and its connection with physically observable quantities. This text presents a stationary formulation of the scattering problem and the wave functions of a particle found in an external field. This book also examines the analytic properties of the scattering matrix, dispersion relations, complex angular moments, as well as the separable representation of the scattering amplitude. Th

  16. Scattering of electromagnetic waves by vortex density structures associated with interchange instability: Analytical and large scale plasma simulation results

    Energy Technology Data Exchange (ETDEWEB)

    Sotnikov, V.; Kim, T.; Lundberg, J. [Air Force Research Laboratory (AFRL/RY), Wright Patterson AFB, Ohio 45433 (United States); Paraschiv, I. [University of Nevada at Reno, Nevada 89557 (United States); Mehlhorn, T. A. [Naval Research Laboratory, Washington, District of Columbia 20375 (United States)


    The presence of plasma turbulence can strongly influence propagation properties of electromagnetic signals used for surveillance and communication. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of coherent vortex structures. Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. These types of density irregularities play an important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics, and in many other applications. We will discuss scattering of high frequency electromagnetic waves on low frequency density irregularities due to the presence of vortex density structures associated with interchange instability. We will also present particle-in-cell simulation results of electromagnetic scattering on vortex type density structures using the large scale plasma code LSP and compare them with analytical results.

  17. Analysis of polarized pulse propagation through one-dimensional scattering medium (United States)

    Zhang, Yong; Yao, Feng-Ju; Xie, Ming; Yi, Hong-Liang


    This paper analyzes the polarized light propagation in a one-dimensional scattering medium with the upper surface subjected to an oblique incident short-pulsed laser beam using the natural element method (NEM). The NEM discretization scheme for the transient vector radiative transfer equation (TVRTE) is presented in detail. The accuracy of the natural element method for transient vector radiative transfer in the scattering medium is assessed. Numerical results show that the NEM is accurate, and effective in solving transient polarized radiative problems. We examine a square short-pulsed laser transport firstly in the atmosphere with Mie scattering and then within aerosol scattering medium. We then investigate the transient polarized radiative transfer problem in the atmosphere-ocean system. The time-resolved signals and the polarization state of the Stokes vector are presented and analyzed. It is found that the scattering types of the medium make greatly influence on the transient transportation of the polarized light. Critically, the polarization states of the backward and forward scattered photons show significantly different time varying trends. For the two-layer system with dissimilar refractive index distributions, due to the total-reflection effect, the existence of a Fresnel interface significantly changes the polarization state of the light, and discontinuous distribution features are observed on the interface.

  18. Microwave analog experiments on optically soft spheroidal scatterers with weak electromagnetic signature (United States)

    Saleh, H.; Charon, J.; Dauchet, J.; Tortel, H.; Geffrin, J.-M.


    Light scattering by optically soft particles is being theoretically investigated in many radiative studies. An interest is growing up to develop approximate methods when the resolution of Maxwell's equations is impractical due to time and/or memory size problems with objects of complex geometries. The participation of experimental studies is important to assess novel approximations when no reference solution is available. The microwave analogy represents an efficient solution to perform such electromagnetic measurements in controlled conditions. In this paper, we take advantage of the particular features of our microwave device to present an extensive experimental study on the electromagnetic scattering by spheroidal particles analogs with low refractive indices, as a first step toward the assessment of micro-organisms with low refractive index and heterogeneities. The spheroidal analogs are machined from a low density material and they mimic soft particles of interest to the light scattering community. The measurements are confronted to simulations obtained with Finite Element Method and T-Matrix method. A good agreement is obtained even with refractive index as low as 1.13. Scattered signals of low intensities are correctly measured and the position of the targets is precisely controlled. The forward scattering measurements show high sensitivity to noise and require careful extraction. The configuration of the measurement device reveals different technical requirements between forward and backward scattering directions. The results open interesting perspectives about novel measurement procedures as well as about the use of high prototyping technologies to manufacture analogs of precise refractive indices and shapes.

  19. Analysis of neutron scattering data: Visualization and parameter estimation

    Energy Technology Data Exchange (ETDEWEB)

    Beauchamp, J.J.; Fedorov, V.; Hamilton, W.A.; Yethiraj, M.


    Traditionally, small-angle neutron and x-ray scattering (SANS and SAXS) data analysis requires measurements of the signal and corrections due to the empty sample container, detector efficiency and time-dependent background. These corrections are then made on a pixel-by-pixel basis and estimates of relevant parameters (e.g., the radius of gyration) are made using the corrected data. This study was carried out in order to determine whether treatment of the detector efficiency and empty sample cell in a more statistically sound way would significantly reduce the uncertainties in the parameter estimators. Elements of experiment design are shortly discussed in this paper. For instance, we studied the way the time for a measurement should be optimally divided between the counting for signal, background and detector efficiency. In Section 2 we introduce the commonly accepted models for small-angle neutron and x-scattering and confine ourselves to the Guinier and Rayleigh models and their minor generalizations. The traditional approaches of data analysis are discussed only to the extent necessary to allow their comparison with the proposed techniques. Section 3 describes the main stages of the proposed method: visual data exploration, fitting the detector sensitivity function, and fitting a compound model. This model includes three additive terms describing scattering by the sampler, scattering with an empty container and a background noise. We compare a few alternatives for the first term by applying various scatter plots and computing sums of standardized squared residuals. Possible corrections due to smearing effects and randomness of estimated parameters are also shortly discussed. In Section 4 the robustness of the estimators with respect to low and upper bounds imposed on the momentum value is discussed. We show that for the available data set the most accurate and stable estimates are generated by models containing double terms either of Guinier's or Rayleigh

  20. Scattering Solar Thermal Concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Giebink, Noel C. [Pennsylvania State Univ., State College, PA (United States)


    concentrator optical efficiency was found to decrease significantly with increasing aperture width beyond 0.5 m due to parasitic waveguide out-coupling loss and low-level absorption that become dominant at larger scale. A heat transfer model was subsequently implemented to predict collector fluid heat gain and outlet temperature as a function of flow rate using the optical model as a flux input. It was found that the aperture width size limitation imposed by the optical efficiency characteristics of the waveguide limits the absolute optical power delivered to the heat transfer element per unit length. As compared to state-of-the-art parabolic trough CPV system aperture widths approaching 5 m, this limitation leads to an approximate factor of order of magnitude increase in heat transfer tube length to achieve the same heat transfer fluid outlet temperature. The conclusion of this work is that scattering solar thermal concentration cannot be implemented at the scale and efficiency required to compete with the performance of current parabolic trough CSP systems. Applied within the alternate context of CPV, however, the results of this work have likely opened up a transformative new path that enables quasi-static, high efficiency CPV to be implemented on rooftops in the form factor of traditional fixed-panel photovoltaics.

  1. Three-Dimensional Microwave Holographic Imaging Employing Forward-Scattered Waves Only

    Directory of Open Access Journals (Sweden)

    Reza K. Amineh


    Full Text Available We propose a three-dimensional microwave holographic imaging method based on the forward-scattered waves only. In the proposed method, one transmitter and multiple receivers perform together a two-dimensional scan on two planar apertures on opposite sides of the inspected domain. The ability to achieve three-dimensional imaging without back-scattered waves enables the imaging of high-loss objects, for example, tissues, where the back-scattered waves may not be available due to low signal-to-noise ratio or nonreciprocal measurement setup. The simulation and experimental results demonstrate the satisfactory performance of the proposed method in providing three-dimensional images. Resolution limits are derived and confirmed with simulation examples.

  2. A study of W W scattering at the LHC

    CERN Document Server

    Nauyock, Farahnaaz


    This thesis presents a study of scattering at the LHC, a proton-proton collider being built at CERN and due to start its first run in 2007. The case where no new particles are discovered before the start of the LHC is analysed. The elastic scattering of is considered and the semileptonic 1 decay channels of the bosons are investigated. Signals and backgrounds are simulated using Atlfast, a fast simulation programme for the ATLAS experiment. This specific channel causes violation of unitarity at 1.2 TeV. Therefore, unitarisation is performed and this leads to different resonance scenarios, five of which are investigated. The final signal to background ratio after applying various kinematic cuts on events is greater than one for all the five scenarios. A comparison between the algorithm and cone algorithm is also performed to find out which jet-finding analysis yields a better signal to background ratio. The algorithm proves very efficient in reducing the background by an approximate factor of 1.5 better than t...

  3. Elliptic scattering equations

    Energy Technology Data Exchange (ETDEWEB)

    Cardona, Carlos [Physics Division, National Center for Theoretical Sciences, National Tsing-Hua University,Hsinchu, Taiwan 30013 (China); Gomez, Humberto [Instituto de Fisica - Universidade de São Paulo,Caixa Postal 66318, 05315-970 São Paulo, SP (Brazil); Facultad de Ciencias Basicas, Universidad Santiago de Cali,Calle 5 62-00 Barrio Pampalinda, Cali, Valle (Colombia)


    Recently the CHY approach has been extended to one loop level using elliptic functions and modular forms over a Jacobian variety. Due to the difficulty in manipulating these kind of functions, we propose an alternative prescription that is totally algebraic. This new proposal is based on an elliptic algebraic curve embedded in a ℂP{sup 2} space. We show that for the simplest integrand, namely the n−gon, our proposal indeed reproduces the expected result. By using the recently formulated Λ−algorithm, we found a novel recurrence relation expansion in terms of tree level off-shell amplitudes. Our results connect nicely with recent results on the one-loop formulation of the scattering equations. In addition, this new proposal can be easily stretched out to hyperelliptic curves in order to compute higher genus.

  4. Deuterium microscopy using 17 MeV deuteron–deuteron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Reichart, Patrick, E-mail:; Moser, Marcus; Greubel, Christoph; Peeper, Katrin; Dollinger, Günther, E-mail:


    Using 17 MeV deuterons as a micrometer focused primary beam, we performed deuterium microscopy by using the deuteron–deuteron (dd) scattering reaction. We describe our new box like detector setup consisting of four double sided silicon strip detectors (DSSSD) with 16 strips on each side, each covering up to 0.5 sr solid angle for coincidence detection. This method becomes a valuable tool for studies of hydrogen incorporation or dynamic processes using deuterium tagging. The background from natural hydrocarbon or water contamination is reduced by the factor 150 ppm of natural abundance of deuterium in hydrogen. Deuterium energies of up to 25 MeV, available at the microprobe SNAKE, are ideal for the analysis of thin freestanding samples so that the scattered particles are transmitted to the detector. The differential cross section for the elastic scattering reaction is about the same as for pp-scattering (~100 mb/sr). The main background due to nuclear reactions is outside the energy window of interest. Deuteron–proton (dp) scattering events give an additional signal for hydrogen atoms, so the H/D-ratio can be monitored in parallel. A deuterium detection limit due to accidental coincidences of 3 at-ppm down to less than 1 at-ppm is demonstrated on deuterated polypropylen sheets as well as thick polycarbonate sheets after various stages of coincidence filtering that is possible with our granular detector.

  5. Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds (United States)

    Pope, Iestyn; Payne, Lukas; Zoriniants, George; Thomas, Evan; Williams, Oliver; Watson, Peter; Langbein, Wolfgang; Borri, Paola


    Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug delivery vehicles, and contrast agents in vivo. In the quest for superior photostability and bio-compatibility, nanodiamonds (NDs) are considered one of the best choices due to their unique structural, chemical, mechanical, and optical properties. So far, mainly fluorescent NDs have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centers with stable optical properties. Here, we show that single non-fluorescing NDs exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp3 vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and ND size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of NDs internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively. PMID:25305746

  6. Contrast enhancement for portal images by combination of subtraction and reprojection processes for Compton scattering. (United States)

    Hariu, Masatsugu; Suda, Yuhi; Chang, Weishan; Myojoyama, Atsushi; Saitoh, Hidetoshi


    For patient setup of the IGRT technique, various imaging systems are currently available. MV portal imaging is performed in identical geometry with the treatment beam so that the portal image provides accurate geometric information. However, MV imaging suffers from poor image contrast due to larger Compton scatter photons. In this work, an original image processing algorithm is proposed to improve and enhance the image contrast without increasing the imaging dose. Scatter estimation was performed in detail by MC simulation based on patient CT data. In the image processing, scatter photons were eliminated and then they were reprojected as primary photons on the assumption that Compton interaction did not take place. To improve the processing efficiency, the dose spread function within the EPID was investigated and implemented on the developed code. Portal images with and without the proposed image processing were evaluated by the image contrast profile. By the subtraction process, the image contrast was improved but the EPID signal was weakened because 15.2% of the signal was eliminated due to the contribution of scatter photons. Hence, these scatter photons were reprojected in the reprojection process. As a result, the tumor, bronchi, mediastinal space and ribs were observed more clearly than in the original image. It was clarified that image processing with the dose spread functions provides stronger contrast enhancement while maintaining a sufficient signal-to-noise ratio. This work shows the feasibility of improving and enhancing the contrast of portal images. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  7. X-ray scatter correction method for dedicated breast computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Sechopoulos, Ioannis [Department of Radiology and Imaging Sciences and Winship Cancer Institute, Emory University School of Medicine, 1701 Upper Gate Drive NE, Suite 5018, Atlanta, Georgia 30322 (United States)


    Purpose: To improve image quality and accuracy in dedicated breast computed tomography (BCT) by removing the x-ray scatter signal included in the BCT projections. Methods: The previously characterized magnitude and distribution of x-ray scatter in BCT results in both cupping artifacts and reduction of contrast and accuracy in the reconstructions. In this study, an image processing method is proposed that estimates and subtracts the low-frequency x-ray scatter signal included in each BCT projection postacquisition and prereconstruction. The estimation of this signal is performed using simple additional hardware, one additional BCT projection acquisition with negligible radiation dose, and simple image processing software algorithms. The high frequency quantum noise due to the scatter signal is reduced using a noise filter postreconstruction. The dosimetric consequences and validity of the assumptions of this algorithm were determined using Monte Carlo simulations. The feasibility of this method was determined by imaging a breast phantom on a BCT clinical prototype and comparing the corrected reconstructions to the unprocessed reconstructions and to reconstructions obtained from fan-beam acquisitions as a reference standard. One-dimensional profiles of the reconstructions and objective image quality metrics were used to determine the impact of the algorithm. Results: The proposed additional acquisition results in negligible additional radiation dose to the imaged breast ({approx}0.4% of the standard BCT acquisition). The processed phantom reconstruction showed substantially reduced cupping artifacts, increased contrast between adipose and glandular tissue equivalents, higher voxel value accuracy, and no discernible blurring of high frequency features. Conclusions: The proposed scatter correction method for dedicated breast CT is feasible and can result in highly improved image quality. Further optimization and testing, especially with patient images, is necessary to

  8. Rotational superradiant scattering in a vortex flow (United States)

    Torres, Theo; Patrick, Sam; Coutant, Antonin; Richartz, Maurício; Tedford, Edmund W.; Weinfurtner, Silke


    When an incident wave scatters off of an obstacle, it is partially reflected and partially transmitted. In theory, if the obstacle is rotating, waves can be amplified in the process, extracting energy from the scatterer. Here we describe in detail the first laboratory detection of this phenomenon, known as superradiance. We observed that waves propagating on the surface of water can be amplified after being scattered by a draining vortex. The maximum amplification measured was 14% +/- 8%, obtained for 3.70 Hz waves, in a 6.25-cm-deep fluid, consistent with the superradiant scattering caused by rapid rotation. We expect our experimental findings to be relevant to black-hole physics, since shallow water waves scattering on a draining fluid constitute an analogue of a black hole, as well as to hydrodynamics, due to the close relation to over-reflection instabilities.

  9. Survey of background scattering from materials found in small-angle neutron scattering. (United States)

    Barker, J G; Mildner, D F R


    Measurements and calculations of beam attenuation and background scattering for common materials placed in a neutron beam are presented over the temperature range of 300-700 K. Time-of-flight (TOF) measurements have also been made, to determine the fraction of the background that is either inelastic or quasi-elastic scattering as measured with a 3He detector. Other background sources considered include double Bragg diffraction from windows or samples, scattering from gases, and phonon scattering from solids. Background from the residual air in detector vacuum vessels and scattering from the 3He detector dome are presented. The thickness dependence of the multiple scattering correction for forward scattering from water is calculated. Inelastic phonon background scattering at small angles for crystalline solids is both modeled and compared with measurements. Methods of maximizing the signal-to-noise ratio by material selection, choice of sample thickness and wavelength, removal of inelastic background by TOF or Be filters, and removal of spin-flip scattering with polarized beam analysis are discussed.

  10. Simple model for molecular scattering (United States)

    Mehta, Nirav; Ticknor, Christopher; Hazzard, Kaden


    The collisions of ultracold molecules are qualitatively different from the collisions of ultracold atoms due to the high density of bimolecular resonances near the collision energy. We present results from a simple N-channel scattering model with square-well channel potentials and constant channel couplings (inside the well) designed to reproduce essential features of chaotic molecular scattering. The potential depths and channel splittings are tuned to reproduce the appropriate density of states for the short-range bimolecular collision complex (BCC), which affords a direct comparison of the resulting level-spacing distribution to that expected from random matrix theory (RMT), namely the so-called Wigner surmise. The density of states also sets the scale for the rate of dissociation from the BCC to free molecules, as approximated by transition state theory (TST). Our model affords a semi-analytic solution for the scattering amplitude in the open channel, and a determinantal equation for the eigenenergies of the short-ranged BCC. It is likely the simplest finite-ranged scattering model that can be compared to expectations from the approximations of RMT, and TST. The validity of these approximations has implications for the many-channel Hubbard model recently developed. This research was funded in part by the National Science Foundation under Grant No. NSF PHY-1125915.

  11. Elastic incoherent neutron scattering operating by varying instrumental energy resolution: principle, simulations, and experiments of the resolution elastic neutron scattering (RENS). (United States)

    Magazù, Salvatore; Migliardo, Federica; Benedetto, Antonio


    The main aim of this paper is to present the scientific case of the resolution elastic neutron scattering (RENS) method that is based on the collection of elastic neutron scattering intensity as a function of the instrumental energy resolution and that is able to extract information on the system dynamical properties from an elastic signal. In this framework, it is shown that in the measured elastic scattering law, as a function of the instrumental energy resolution, an inflection point occurs when the instrumental energy resolution intersects the system relaxation time, and in an equivalent way, a transition in the temperature behavior of the measured elastic scattering law occurs when the characteristic system relaxation time crosses the instrumental energy resolution time. With regard to the latter, an operative protocol to determine the system characteristic time by different elastic incoherent neutron scattering (EINS) thermal scans at different instrumental energy resolutions is also proposed. The proposed method, hence, is not primarily addressed to collect the measured elastic scattering intensity with a great accuracy, but rather relies on determining an inflection point in the measured elastic scattering law versus instrumental energy resolution. The RENS method is tested both numerically and experimentally. As far as numerical simulations are concerned, a simple model system for which the temperature behavior of the relaxation time follows an Arrhenius law, while its scattering law follows a Gaussian behavior, is considered. It is shown that the system relaxation time used as an input for the simulations coincides with the one obtained by the RENS approach. Regarding the experimental findings, due to the fact that a neutron scattering spectrometer working following the RENS method has not been constructed yet, different EINS experiments with different instrumental energy resolutions were carried out on a complex model system, i.e., dry and D(2)O hydrated

  12. Detuned surface plasmon resonance scattering of gold nanorods for continuous wave multilayered optical recording and readout. (United States)

    Taylor, Adam B; Kim, Jooho; Chon, James W M


    In a multilayered structure of absorptive optical recording media, continuous-wave laser operation is highly disadvantageous due to heavy beam extinction. For a gold nanorod based recording medium, the narrow surface plasmon resonance (SPR) profile of gold nanorods enables the variation of extinction through mulilayers by a simple detuning of the readout wavelength from the SPR peak. The level of signal extinction through the layers can then be greatly reduced, resulting more efficient readout at deeper layers. The scattering signal strength may be decreased at the detuned wavelength, but balancing these two factors results an optimal scattering peak wavelength that is specific to each layer. In this paper, we propose to use detuned SPR scattering from gold nanorods as a new mechanism for continuous-wave readout scheme on gold nanorod based multilayered optical storage. Using this detuned scattering method, readout using continuous-wave laser is demonstrated on a 16 layer optical recording medium doped with heavily distributed, randomly oriented gold nanorods. Compared to SPR on-resonant readout, this method reduced the required readout power more than one order of magnitude, with only 60 nm detuning from SPR peak. The proposed method will be highly beneficial to multilayered optical storage applications as well as applications using a continuous medium doped heavily with plasmonic nanoparticles.

  13. Scattering anomaly in optics

    CERN Document Server

    Silveirinha, Mario G


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

  14. Scattering of Skyrmions

    Directory of Open Access Journals (Sweden)

    David Foster


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

  15. Lidar measured vertical atmospheric scattering profiles

    NARCIS (Netherlands)

    Kunz, G.J.


    The vertical structure of the atmosphere, which is of invaluable interest to meteorologists, geo-physicists and environmental researchers, can be measured with LIDAR. A method has been proposed and applied to invert lidar signals from vertical soundings to height resolved scattering coefficients. In

  16. Studying the Bridge-Type Parametric Scatterer (United States)

    Babanov, N. Yu.; Klyuev, A. V.; Lartsov, S. V.; Samarin, V. P.


    We study a parametric scatterer representing a quadripole of four bridge-type parametric circuits with antennas connected to the circuit arms and tuned to the pump signal and its half-wave subharmonic on the basis of simulation and full-scale experiments in the frequency range near 800 MHz.

  17. Multiple Scatters in Single Site Gamma Backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, J. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    nEXO aims to reduce its gamma backgrounds by taking advantage of the fact that a large number of gammas that would otherwise be backgrounds will undergo multiple compton scattering in the TPC and produce spatially distinct signals. These multi-sited (MS) events can be excluded from the 0νββ search.

  18. Introduction to neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, W.E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)


    We give here an introduction to the theoretical principles of neutron scattering. The relationship between scattering- and correlation-functions is particularly emphasized. Within the framework of linear response theory (justified by the weakness of the basic interaction) the relation between fluctuation and dissipation is discussed. This general framework explains the particular power of neutron scattering as an experimental method. (author) 4 figs., 4 refs.

  19. Elastic scattering phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Mackintosh, R.S. [The Open University, School of Physical Sciences, Milton Keynes (United Kingdom)


    We argue that, in many situations, fits to elastic scattering data that were historically, and frequently still are, considered ''good'', are not justifiably so describable. Information about the dynamics of nucleon-nucleus and nucleus-nucleus scattering is lost when elastic scattering phenomenology is insufficiently ambitious. It is argued that in many situations, an alternative approach is appropriate for the phenomenology of nuclear elastic scattering of nucleons and other light nuclei. The approach affords an appropriate means of evaluating folding models, one that fully exploits available empirical data. It is particularly applicable for nucleons and other light ions. (orig.)

  20. Collective Thomson scattering energetic particle diagnostic in high performance tokamaks. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, P.Y.; Aamodt, R.E.; Russell, D.A.


    This report summarizes the work performed under DOE grant DE-FG03-95ER54334. Lodestar was an active participant in the low power Collective Thomson Scattering (CTS) diagnostic experiment at TFTR in collaboration with MIT. A simple and effective fitting technique was developed to extract key parameters from the scattered data. Utilizing this new technique, the concept of lower hybrid resonance scattering was adapted for a feasibility study of a low/medium power collective scattering diagnostic for ITER. The implementation and the testing of such a technique for actual parameter extraction using TFTR data, however, was severely limited due to experimental and instrumentation complications. Based on the studies the authors have performed up to date, it is believed that a combination of non-physics related effects such as multiple wall reflection of incident signal and spectral impurity problem o the gyrotron can account for the anomalous signal strength. A collaborative effort with GA was initiated and a feasibility study of developing and implementing a collective thomson scattering (CTS) diagnostic for the detection of energetic particles at DIII-D was completed. Specifically, the process of selecting an optimum receiver location for the diagnostic is discussed in detailed. Results presented here include detailed signal to noise calculations and ray-tracing studies. Critical physics issues and selection criteria are discussed and a procedure to detect anisotropic energetic ion temperatures is also outlined. Favorable results, obtained in the feasibility study, indicate that it should be possible to develop and implement a CTS diagnostic at DIII-D.

  1. Noncommutative quantum mechanics and skew scattering in ferromagnetic metals (United States)

    Ishizuka, Hiroaki; Nagaosa, Naoto


    The anomalous Hall effect is classified into two effects based on the mechanism. The first one is the intrinsic Hall effect due to the Berry curvature in momentum space. This is a Hall effect that solely arises from the band structure of solids. On the other hand, another contribution to the Hall effect, the so-called extrinsic mechanism, comes from impurity scatterings such as skew scattering and side jump. These two mechanisms are often discussed separately; the intrinsic Hall effect is related to the Berry curvature of the band while the skew scattering is studied using the scattering theory approaches. However, we here show that, in an electronic system with finite Berry curvature, the skew scattering by nonmagnetic impurities is described by the noncommutative nature of the real-space coordinates due to the Berry curvature of the Block wave functions. The anomalous Hall effect due to this skew scattering is estimated and compared with the intrinsic contribution.

  2. Quantitative considerations in medium energy ion scattering depth profiling analysis of nanolayers

    Energy Technology Data Exchange (ETDEWEB)

    Zalm, P.C.; Bailey, P. [International Institute for Accelerator Applications, University of Huddersfield, Queensgate, Huddersfield HD1 3DH (United Kingdom); Reading, M.A. [Physics and Materials Research Centre, University of Salford, Salford M5 4WT (United Kingdom); Rossall, A.K. [International Institute for Accelerator Applications, University of Huddersfield, Queensgate, Huddersfield HD1 3DH (United Kingdom); Berg, J.A. van den, E-mail: [International Institute for Accelerator Applications, University of Huddersfield, Queensgate, Huddersfield HD1 3DH (United Kingdom)


    The high depth resolution capability of medium energy ion scattering (MEIS) is becoming increasingly relevant to the characterisation of nanolayers in e.g. microelectronics. In this paper we examine the attainable quantitative accuracy of MEIS depth profiling. Transparent but reliable analytical calculations are used to illustrate what can ultimately be achieved for dilute impurities in a silicon matrix and the significant element-dependence of the depth scale, for instance, is illustrated this way. Furthermore, the signal intensity-to-concentration conversion and its dependence on the depth of scattering is addressed. Notably, deviations from the Rutherford scattering cross section due to screening effects resulting in a non-coulombic interaction potential and the reduction of the yield owing to neutralization of the exiting, backscattered H{sup +} and He{sup +} projectiles are evaluated. The former mainly affects the scattering off heavy target atoms while the latter is most severe for scattering off light target atoms and can be less accurately predicted. However, a pragmatic approach employing an extensive data set of measured ion fractions for both H{sup +} and He{sup +} ions scattered off a range of surfaces, allows its parameterization. This has enabled the combination of both effects, which provides essential information regarding the yield dependence both on the projectile energy and the mass of the scattering atom. Although, absolute quantification, especially when using He{sup +}, may not always be achievable, relative quantification in which the sum of all species in a layer adds up to 100%, is generally possible. This conclusion is supported by the provision of some examples of MEIS derived depth profiles of nanolayers. Finally, the relative benefits of either using H{sup +} or He{sup +} ions are briefly considered.

  3. Parity Violation in Forward Angle Elastic Electron-Proton Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Miller, IV, Grady Wilson [Princeton Univ., NJ (United States)


    We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton at Jefferson Laboratory. The kinematic point (θlab = 12.3 deg. and (Q2) = 0.48 (GeV/c)2) is chosen to provide sensitivity to the strange electric form factor GsE. A 3.36 GeV beam of longitudinally polarized electrons was scattered from protons in a liquid hydrogen target. The scattered flux was detected by a pair of spectrometers which focussed the elastically-scattered electrons onto total-absorption detectors. The detector signals were integrated and digitized by a custom data acquisition system. A feedback system reduced systematic errors by controlling helicity-correlated beam intensity differences at the sub-ppm (part per million) level. The experimental result, A = 14.5 +/- 2.0 (stat) ± 1.1 (syst) ppm, is consistent with the electroweak Standard Model with no additional contributions from strange quarks. In particular, the measurement implies GSE + 0.39 GsM = 0.023 ± 0.040 ± 0.026 (ζGnE), where the last uncertainty is due to the estimated uncertainty in the neutron electric form factor GnE . This result represents the first experimental constraint of the strange electric form factor.

  4. Alternative method for determining the constant offset in lidar signal. (United States)

    Kovalev, Vladimir A; Wold, Cyle; Petkov, Alexander; Hao, Wei Min


    We present an alternative method for determining the total offset in lidar signal created by a daytime background-illumination component and electrical or digital offset. Unlike existing techniques, here the signal square-range-correction procedure is initially performed using the total signal recorded by lidar, without subtraction of the offset component. While performing the square-range correction, the lidar-signal monotonic change due to the molecular component of the atmosphere is simultaneously compensated. After these corrections, the total offset is found by determining the slope of the above transformed signal versus a function that is defined as a ratio of the squared range and two molecular scattering components, the backscatter and transmittance. The slope is determined over a far end of the measurement range where aerosol loading is zero or, at least, minimum. An important aspect of this method is that the presence of a moderate aerosol loading over the far end does not increase dramatically the error in determining the lidar-signal offset. The comparison of the new technique with a conventional technique of the total-offset estimation is made using simulated and experimental data. The one-directional and multiangle measurements are analyzed and specifics in the estimate of the uncertainty limits due to remaining shifts in the inverted lidar signals are discussed. The use of the new technique allows a more accurate estimate of the signal constant offset, and accordingly, yields more accurate lidar-signal inversion results.

  5. Compton scatter correction for planner scintigraphic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Vaan Steelandt, E.; Dobbeleir, A.; Vanregemorter, J. [Algemeen Ziekenhuis Middelheim, Antwerp (Belgium). Dept. of Nuclear Medicine and Radiotherapy


    A major problem in nuclear medicine is the image degradation due to Compton scatter in the patient. Photons emitted by the radioactive tracer scatter in collision with electrons of the surrounding tissue. Due to the resulting loss of energy and change in direction, the scattered photons induce an object dependant background on the images. This results in a degradation of the contrast of warm and cold lesions. Although theoretically interesting, most of the techniques proposed in literature like the use of symmetrical photopeaks can not be implemented on the commonly used gamma camera due to the energy/linearity/sensitivity corrections applied in the detector. A method for a single energy isotope based on existing methods with adjustments towards daily practice and clinical situations is proposed. It is assumed that the scatter image, recorded from photons collected within a scatter window adjacent to the photo peak, is a reasonable close approximation of the true scatter component of the image reconstructed from the photo peak window. A fraction `k` of the image using the scatter window is subtracted from the image recorded in the photo peak window to produce the compensated image. The principal matter of the method is the right value for the factor `k`, which is determined in a mathematical way and confirmed by experiments. To determine `k`, different kinds of scatter media are used and are positioned in different ways in order to simulate a clinical situation. For a secondary energy window from 100 to 124 keV below a photo peak window from 126 to 154 keV, a value of 0.7 is found. This value has been verified using both an antropomorph thyroid phantom and the Rollo contrast phantom.

  6. Wave propagation, scattering and emission in complex media (United States)

    Jin, Ya-Qiu

    I. Polarimetric scattering and SAR imagery. EM wave propagation and scattering in polarimetric SAR interferometry / S. R. Cloude. Terrain topographic inversion from single-pass polarimetric SAR image data by using polarimetric stokes parameters and morphological algorithm / Y. Q. Jin, L. Luo. Road detection in forested area using polarimetric SAR / G. W. Dong ... [et al.]. Research on some problems about SAR radiometric resolution / G. Dong ... [et al.]. A fast image matching algorithm for remote sensing applications / Z. Q. Hou ... [et al.]. A new algorithm of noised remote sensing image fusion based on steerable filters / X. Kang ... [et al.]. Adaptive noise reduction of InSAR data based on anisotropic diffusion models and their applications to phase unwrapping / C. Wang, X. Gao, H. Zhang -- II. Scattering from randomly rough surfaces. Modeling tools for backscattering from rough surfaces / A. K. Fung, K. S. Chen. Pseudo-nondiffracting beams from rough surface scattering / E. R. Méndez, T. A. Leskova, A. A. Maradudin. Surface roughness clutter effects in GPR modeling and detection / C. Rappaport. Scattering from rough surfaces with small slopes / M. Saillard, G. Soriano. Polarization and spectral characteristics of radar signals reflected by sea-surface / V. A. Butko, V. A. Khlusov, L. I. Sharygina. Simulation of microwave scattering from wind-driven ocean surfaces / M. Y. Xia ... [et al.]. HF surface wave radar tests at the Eastern China Sea / X. B. Wu ... [et al.] -- III. Electromagnetics of complex materials. Wave propagation in plane-parallel metamaterial and constitutive relations / A. Ishimaru ... [et al.]. Two dimensional periodic approach for the study of left-handed metamaterials / T. M. Grzegorczyk ... [et al.]. Numerical analysis of the effective constitutive parameters of a random medium containing small chiral spheres / Y. Nanbu, T. Matsuoka, M. Tateiba. Wave propagation in inhomogeneous media: from the Helmholtz to the Ginzburg -Landau equation / M

  7. A practical cone-beam CT scatter correction method with optimized Monte Carlo simulations for image-guided radiation therapy (United States)

    Xu, Yuan; Bai, Ti; Yan, Hao; Ouyang, Luo; Pompos, Arnold; Wang, Jing; Zhou, Linghong; Jiang, Steve B.; Jia, Xun


    Cone-beam CT (CBCT) has become the standard image guidance tool for patient setup in image-guided radiation therapy. However, due to its large illumination field, scattered photons severely degrade its image quality. While kernel-based scatter correction methods have been used routinely in the clinic, it is still desirable to develop Monte Carlo (MC) simulation-based methods due to their accuracy. However, the high computational burden of the MC method has prevented routine clinical application. This paper reports our recent development of a practical method of MC-based scatter estimation and removal for CBCT. In contrast with conventional MC approaches that estimate scatter signals using a scatter-contaminated CBCT image, our method used a planning CT image for MC simulation, which has the advantages of accurate image intensity and absence of image truncation. In our method, the planning CT was first rigidly registered with the CBCT. Scatter signals were then estimated via MC simulation. After scatter signals were removed from the raw CBCT projections, a corrected CBCT image was reconstructed. The entire workflow was implemented on a GPU platform for high computational efficiency. Strategies such as projection denoising, CT image downsampling, and interpolation along the angular direction were employed to further enhance the calculation speed. We studied the impact of key parameters in the workflow on the resulting accuracy and efficiency, based on which the optimal parameter values were determined. Our method was evaluated in numerical simulation, phantom, and real patient cases. In the simulation cases, our method reduced mean HU errors from 44 to 3 HU and from 78 to 9 HU in the full-fan and the half-fan cases, respectively. In both the phantom and the patient cases, image artifacts caused by scatter, such as ring artifacts around the bowtie area, were reduced. With all the techniques employed, we achieved computation time of less than 30 s including the

  8. Neutron scattering from fractals

    DEFF Research Database (Denmark)

    Kjems, Jørgen; Freltoft, T.; Richter, D.


    -angle neutron scattering studies of the variation with aggregation rate are presented. These results allow a very detailed comparison to be made with the theoretical scattering curves. Preliminary incoherent inelastic data on the low-frequency dynamics of hydroxylated silica particle aggregates show a clear...

  9. Incoherent Thomson scattering

    NARCIS (Netherlands)

    Donne, A. J. H.


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

  10. Purely bianisotropic scatterers (United States)

    Albooyeh, M.; Asadchy, V. S.; Alaee, R.; Hashemi, S. M.; Yazdi, M.; Mirmoosa, M. S.; Rockstuhl, C.; Simovski, C. R.; Tretyakov, S. A.


    The polarization response of molecules or meta-atoms to external electric and magnetic fields, which defines the electromagnetic properties of materials, can either be direct (electric field induces electric moment and magnetic field induces magnetic moment) or indirect (magnetoelectric coupling in bianisotropic scatterers). Earlier studies suggest that there is a fundamental bound on the indirect response of all passive scatterers: It is believed to be always weaker than the direct one. In this paper, we prove that there exist scatterers which overcome this bound substantially. Moreover, we show that the amplitudes of electric and magnetic polarizabilities can be negligibly small as compared to the magnetoelectric coupling coefficients. However, we prove that if at least one of the direct-excitation coefficients vanishes, magnetoelectric coupling effects in passive scatterers cannot exist. Our findings open a way to a new class of electromagnetic scatterers and composite materials.

  11. Bistatic Forward Scattering Radar Detection and Imaging

    Directory of Open Access Journals (Sweden)

    Hu Cheng


    Full Text Available Forward Scattering Radar (FSR is a special type of bistatic radar that can implement image detection, imaging, and identification using the forward scattering signals provided by the moving targets that cross the baseline between the transmitter and receiver. Because the forward scattering effect has a vital significance in increasing the targets’ Radar Cross Section (RCS, FSR is quite advantageous for use in counter stealth detection. This paper first introduces the front line technology used in forward scattering RCS, FSR detection, and Shadow Inverse Synthetic Aperture Radar (SISAR imaging and key problems such as the statistical characteristics of forward scattering clutter, accurate parameter estimation, and multitarget discrimination are then analyzed. Subsequently, the current research progress in FSR detection and SISAR imaging are described in detail, including the theories and experiments. In addition, with reference to the BeiDou navigation satellite, the results of forward scattering experiments in civil aircraft detection are shown. Finally, this paper considers future developments in FSR target detection and imaging and presents a new, promising technique for stealth target detection.

  12. Narrowband Compton Scattering Yield Enhancement (United States)

    Rykovanov, Sergey; Seipt, Daniel; Kharin, Vasily


    Compton Scattering (CS) of laser light off high-energy electrons is a well-established source of X- and gamma-rays for applications in medicine, biology, nuclear and material sciences. Main advantage of CS photon sources is the possibility to generate narrow spectra as opposed to a broad continuum obtained when utilizing Bremsstrahlung. However, due to the low cross-section of the linear process, the total photon yield is quite low. The most straightforward way to increase the number of photon-electron beam scattering events is to increase the laser pulse intensity at the interaction point by harder focusing. This leads to an unfortunate consequence. Increase in the laser pulse normalized amplitude a0, leads to additional ponderomotive spectrum broadening of the scattered radiation. The ponderomotive broadening is caused by the v × B force, which slows the electron down near the peak of the laser pulse where the intensity is high, and can be neglected near the wings of the pulse, where the intensity is low. We show that laser pulse chirping, both nonlinear (laser pulse frequency ''following'' the envelope of the pulse) and linear, leads to compensation of the ponderomotive broadening and considerably enhances the yield of the nonlinear Compton sources. Work supported by the Helmholtz Association via Helmholtz Young Investigators Grant (VH-NG-1037).

  13. Manipulating scattering features by metamaterials

    Directory of Open Access Journals (Sweden)

    Lu Cui


    Full Text Available We present a review on manipulations of electromagnetic scattering features by using metamaterials or metasurfaces. Several approaches in controlling the scattered fields of objects are presented, including invisibility cloaks and radar illusions based on transformation optics, carpet cloak using gradient metamaterials, dc cloaks, mantle cloaks based on scattering cancellation, “skin” cloaks using phase compensation, scattering controls with coding/programmable metasurfaces, and scattering reductions by multilayered structures. Finally, the future development of metamaterials on scattering manipulation is predicted.

  14. Modelling Hyperboloid Sound Scattering

    DEFF Research Database (Denmark)

    Burry, Jane; Davis, Daniel; Peters, Brady


    The Responsive Acoustic Surfaces workshop project described here sought new understandings about the interaction between geometry and sound in the arena of sound scattering. This paper reports on the challenges associated with modelling, simulating, fabricating and measuring this phenomenon using...... both physical and digital models at three distinct scales. The results suggest hyperboloid geometry, while difficult to fabricate, facilitates sound scattering.......The Responsive Acoustic Surfaces workshop project described here sought new understandings about the interaction between geometry and sound in the arena of sound scattering. This paper reports on the challenges associated with modelling, simulating, fabricating and measuring this phenomenon using...

  15. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael


    We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...

  16. Epi-detection of vibrational phase contrast coherent anti-Stokes Raman scattering

    NARCIS (Netherlands)

    Garbacik, E.T.; Korterik, Jeroen P.; Otto, Cornelis; Herek, Jennifer Lynn; Offerhaus, Herman L.


    We demonstrate a system for the phase-resolved epi-detection of coherent anti-Stokes Raman scattering (CARS) signals in highly scattering and/or thick samples. With this setup, we measure the complex vibrational responses of multiple components in a thick, highly-scattering pharmaceutical tablet in

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

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


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

  18. Barrier distributions from elastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, N. [Manchester Univ. (United Kingdom). Dept. of Physics]|[Surrey Univ., Guildford (United Kingdom). Dept. of Physics; Timmers, H.; Leigh, J.R.; Masgupta, M.; Hinde, D.J.; Mein, J.C.; Morton, C.R.; Newton, J.O. [Australian National Univ., Canberra, ACT (Australia). Dept. of Nuclear Physics


    A new representation of the distribution of potential barriers present in heavy ion reactions is defined in terms of the elastic scattering excitation function. Its validity is demonstrated for the systems {sup 16}0 + {sup 144,} {sup 154}Sm, {sup 186}W, {sup 208}Pb, for which precise measurements have been made. Compared with fusion barrier distributions, which show structures characteristic of collective inelastic couplings, the elastic distributions are less detailed. This appears to be due to couplings to weaker direct reaction channels. 20 refs., 3 figs.

  19. Measurements of scattering and absorption in mammalian cell suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Mourant, J.R.; Johnson, T.M.; Freyer, J.P.


    During the past several years a range of spectroscopies, including fluorescence and elastic-scatter spectroscopy, have been investigated for optically based detection of cancer and other tissue pathologies. Both elastic-scatter and fluorescence signals depend, in part, on scattering and absorption properties of the cells in the tissue. Therefore an understanding of the scattering and absorption properties of cells is a necessary prerequisite for understanding and developing these techniques. Cell suspensions provide a simple model with which to begin studying the absorption and scattering properties of cells. In this study we have made preliminary measurements of the scattering and absorption properties of suspensions of mouse mammary carcinoma cells (EMT6) over a broad wavelength range (380 nm to 800 nm).

  20. Measurements of scattering and absorption in mammalian cell suspensions (United States)

    Mourant, Judith R.; Freyer, James P.; Johnson, Tamara M.


    During the past several years a range of spectroscopies, including fluorescence and elastic- scatter spectroscopy, have been investigated for optically based detection of cancer and other tissue pathologies. Both elastic-scatter and fluorescence signals depend, in part, on scattering and absorption properties of the cells in the tissue. Therefore an understanding of the scattering and absorption properties of cells is a necessary prerequisite for understanding and developing these techniques. Cell suspensions provide a simple model with which to begin studying the absorption and scattering properties of cells. In this study we have made preliminary measurements of the scattering and absorption properties of suspensions of mouse mammary carcinoma cells (EMT6) over a broad wavelength range (380 nm to 800 nm).

  1. Heterodyne x-ray diffuse scattering from coherent phonons. (United States)

    Kozina, M; Trigo, M; Chollet, M; Clark, J N; Glownia, J M; Gossard, A C; Henighan, T; Jiang, M P; Lu, H; Majumdar, A; Zhu, D; Reis, D A


    Here, we report Fourier-transform inelastic x-ray scattering measurements of photoexcited GaAs with embedded ErAs nanoparticles. We observe temporal oscillations in the x-ray scattering intensity, which we attribute to inelastic scattering from coherent acoustic phonons. Unlike in thermal equilibrium, where inelastic x-ray scattering is proportional to the phonon occupation, we show that the scattering is proportional to the phonon amplitude for coherent states. The wavevectors of the observed phonons extend beyond the excitation wavevector. The nanoparticles break the discrete translational symmetry of the lattice, enabling the generation of large wavevector coherent phonons. Elastic scattering of x-ray photons from the nanoparticles provides a reference for heterodyne mixing, yielding signals proportional to the phonon amplitude.

  2. Detection of volatile organic compounds using surface enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Chang, A S; Maiti, A; Ileri, N; Bora, M; Larson, C C; Britten, J A; Bond, T C


    The authors present the detection of volatile organic compounds directly in their vapor phase by surface-enhanced Raman scattering (SERS) substrates based on lithographically-defined two-dimensional rectangular array of nanopillars. The type of nanopillars is known as the tapered pillars. For the tapered pillars, SERS enhancement arises from the nanofocusing effect due to the sharp tip on top. SERS experiments were carried out on these substrates using various concentrations of toluene vapor. The results show that SERS signal from a toluene vapor concentration of ppm level can be achieved, and the toluene vapor can be detected within minutes of exposing the SERS substrate to the vapor. A simple adsorption model is developed which gives results matching the experimental data. The results also show promising potential for the use of these substrates in environmental monitoring of gases and vapors.

  3. Applied electromagnetic scattering theory

    CERN Document Server

    Osipov, Andrey A


    Besides classical applications (radar and stealth, antennas, microwave engineering), scattering and diffraction are enabling phenomena for some emerging research fields (artificial electromagnetic materials or metamaterials, terahertz technologies, electromagnetic aspects of nano-science). This book is a tutorial for advanced students who need to study diffraction theory. The textbook gives fundamental knowledge about scattering and diffraction of electromagnetic waves and provides some working examples of solutions for practical high-frequency scattering and diffraction problems. The book focuses on the most important diffraction effects and mechanisms influencing the scattering process and describes efficient and physically justified simulation methods - physical optics (PO) and the physical theory of diffraction (PTD) - applicable in typical remote sensing scenarios. The material is presented in a comprehensible and logical form, which relates the presented results to the basic principles of electromag...

  4. Gravitational Bhabha scattering (United States)

    Santos, A. F.; Khanna, Faqir C.


    Gravitoelectromagnetism (GEM) as a theory for gravity has been developed similar to the electromagnetic field theory. A weak field approximation of Einstein theory of relativity is similar to GEM. This theory has been quantized. Traditional Bhabha scattering, electron-positron scattering, is based on quantized electrodynamics theory. Usually the amplitude is written in terms of one photon exchange process. With the development of quantized GEM theory, the scattering amplitude will have an additional component based on an exchange of one graviton at the lowest order of perturbation theory. An analysis will provide the relative importance of the two amplitudes for Bhabha scattering. This will allow an analysis of the relative importance of the two amplitudes as the energy of the exchanged particles increases.

  5. Algorithmic scatter correction in dual-energy digital mammography

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xi; Mou, Xuanqin [Institute of Image Processing and Pattern Recognition, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Nishikawa, Robert M.; Lau, Beverly A. [Department of Radiology, The University of Chicago, Chicago, Illinois 60637 (United States); Chan, Suk-tak [Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hung Hom (Hong Kong); Zhang, Lei [Department of Computing, The Hong Kong Polytechnic University, Hung Hom (Hong Kong)


    Purpose: Small calcifications are often the earliest and the main indicator of breast cancer. Dual-energy digital mammography (DEDM) has been considered as a promising technique to improve the detectability of calcifications since it can be used to suppress the contrast between adipose and glandular tissues of the breast. X-ray scatter leads to erroneous calculations of the DEDM image. Although the pinhole-array interpolation method can estimate scattered radiations, it requires extra exposures to measure the scatter and apply the correction. The purpose of this work is to design an algorithmic method for scatter correction in DEDM without extra exposures.Methods: In this paper, a scatter correction method for DEDM was developed based on the knowledge that scattered radiation has small spatial variation and that the majority of pixels in a mammogram are noncalcification pixels. The scatter fraction was estimated in the DEDM calculation and the measured scatter fraction was used to remove scatter from the image. The scatter correction method was implemented on a commercial full-field digital mammography system with breast tissue equivalent phantom and calcification phantom. The authors also implemented the pinhole-array interpolation scatter correction method on the system. Phantom results for both methods are presented and discussed. The authors compared the background DE calcification signals and the contrast-to-noise ratio (CNR) of calcifications in the three DE calcification images: image without scatter correction, image with scatter correction using pinhole-array interpolation method, and image with scatter correction using the authors' algorithmic method.Results: The authors' results show that the resultant background DE calcification signal can be reduced. The root-mean-square of background DE calcification signal of 1962 μm with scatter-uncorrected data was reduced to 194 μm after scatter correction using the authors' algorithmic method

  6. Neutron scattering in dimers

    DEFF Research Database (Denmark)

    Gudel, H. U.; Furrer, A.; Kjems, Jørgen


    Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer excitati......Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer...

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

    Piwinski, Anton


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

  8. Study of multiple scattering effects in heavy ion RBS

    Energy Technology Data Exchange (ETDEWEB)

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


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

  9. Impact of ICRH on the measurement of fusion alphas by collective Thomson scattering in ITER

    DEFF Research Database (Denmark)

    Salewski, Mirko; Eriksson, L.-G.; Bindslev, Henrik


    Collective Thomson scattering (CTS) has been proposed for measuring the phase space distributions of confined fast ion populations in ITER plasmas. This study determines the impact of fast ions accelerated by ion cyclotron resonance heating (ICRH) on the ability of CTS to diagnose fusion alphas......, corresponding to an off-axis resonance. The sensitivities of the results to the He-3 concentration (0.1-4%) and the heating power (20-40 MW) are considered. Fusion born alphas dominate the total CTS signal for large Doppler shifts of the scattered radiation. The tritons generate a negligible fraction...... perpendicular velocities, it may be difficult to draw conclusions about the physics of alpha particles alone by CTS. With this exception, the CTS diagnostic can reveal the physics of the fusion alphas in ITER even under the presence of fast ions due to ICRH....

  10. Polarization dependence of tip-enhanced Raman and plasmon-resonance Rayleigh scattering spectra (United States)

    Kitahama, Yasutaka; Uemura, Shohei; Katayama, Ryota; Suzuki, Toshiaki; Itoh, Tamitake; Ozaki, Yukihiro


    Tip-enhanced Raman scattering (TERS) spectroscopy has high sensitivity and high spatial resolution, although it shows low reproducibility due to the variable optical properties of the tips. In the present study, polarized scattering spectra of localized surface plasmon resonance (LSPR) at the apex of the tip induced by conventional dark field illumination were compared with the corresponding TERS spectra, generated by excitation using polarization not only parallel and perpendicular to the tip, but also vertical to the sample plane (z-polarization). The polarization-dependence of LSPR was consistent with that of the TERS. Thus, the optical properties of the tip can be easily optimized before TERS measurement by excitation polarization that induces the largest LSPR signal.

  11. Impact of carbon nanotube geometrical volume on nonlinear absorption and scattering properties (United States)

    Nair, Vijayakumar Sadasivan; Pusala, Aditya; Hatamimoslehabadi, Maryam; Yelleswarapu, Chandra S.


    Nonlinear optical (NLO) properties of carbon nanostructures are of great interest due to their broadband spectral response. As carbon nanotubes (CNTs) can be synthesized with various lengths, thicknesses, and numbers of layers, their optical properties can also be different. We have performed side-by-side comparative studies of the relationship between the geometrical volume and NLO properties of CNTs. The real and imaginary components of the third order optical nonlinearity are obtained using well-known Z-scan technique. While the transmission and scattered light are detected using photodiodes, the generated photoacoustic signal is recorded simultaneously using an ultrasonic transducer. Results show an inverse relationship between the volume of CNTs and their NLO properties. This can be attributed to the availability of more nanoparticles within the laser beam profile and concurrent generation of scattering sites upon the absorption of incident radiation.

  12. Feasibility of Single Molecule DNA Sequencing using Surface-Enhanced Raman Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Talley, C E; Reboredo, F; Chan, J; Lane, S M


    We have used a combined theoretical and experimental approach in order to assess the feasibility of using surface-enhanced Raman scattering (SERS) for DNA sequencing at the single molecule level. We have developed a numerical tool capable of calculating the E-field and resulting SERS enhancement factors for metallic structures of arbitrary size and shape. Measurements of the additional SERS enhancement by combining SERS with coherent antistokes Raman scattering (CARS) show that only modest increases in the signal are achievable due to thermal damage at higher laser powers. Finally, measurements of the SERS enhancement from nanoparticles coated with an insulating layer show that the SERS enhancement is decreased by as much as two orders of magnitude when the molecule is not in contact with the metal surface.

  13. Extraction of scattering echo time by surf noise background subtracted autocorrelation. (United States)

    Li, Xiaolei; Chi, Jing; Gao, Dazhi; Li, Jie; Wang, Ning


    Extracting echo time is an important step in scatterer detection by ambient noise, while in general the scattered signal is weak and submerged in the background. An experiment of a Polyvinyl chloride pipe in a coastline surf noise environment is designed to extract the pipe's echo time by noise autocorrelation. As expected, the scattered wave of the pipe is submerged in an autocorrelation signal. A method called background subtracted autocorrelation is proposed in this paper, which can retrieve scattered echo time from autocorrelation signal effectively. And the biggest relative error of extracted echo time is less than 2% in the experiment.

  14. Rigorous numerical modeling of scattering-type scanning near-field optical microscopy and spectroscopy (United States)

    Chen, Xinzhong; Lo, Chiu Fan Bowen; Zheng, William; Hu, Hai; Dai, Qing; Liu, Mengkun


    Over the last decade, scattering-type scanning near-field optical microscopy and spectroscopy have been widely used in nano-photonics and material research due to their fine spatial resolution and broad spectral range. A number of simplified analytical models have been proposed to quantitatively understand the tip-scattered near-field signal. However, a rigorous interpretation of the experimental results is still lacking at this stage. Numerical modelings, on the other hand, are mostly done by simulating the local electric field slightly above the sample surface, which only qualitatively represents the near-field signal rendered by the tip-sample interaction. In this work, we performed a more comprehensive numerical simulation which is based on realistic experimental parameters and signal extraction procedures. By directly comparing to the experiments as well as other simulation efforts, our methods offer a more accurate quantitative description of the near-field signal, paving the way for future studies of complex systems at the nanoscale.

  15. Low-energy positron scattering upon endohedrals (United States)

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


    We investigate positron scattering upon endohedrals and compare it with electron-endohedral scattering. We show that the polarization of the fullerene shell considerably alters the polarization potential of an atom, stuffed inside a fullerene. This essentially affects both the positron and electron elastic scattering phases as well as corresponding cross sections. Of great importance is also the interaction between the incoming positron and the target electrons that leads to formation of the virtual positronium P˜s. We illustrate the general trend by concrete examples of positron and electron scattering upon endohedrals He@C60 and Ar@C60, and compare it to scattering upon fullerene C60. To obtain the presented results, we have employed new simplified approaches that permit to incorporate the effect of fullerenes polarizability into the He@C60 and Ar@C60 polarization potential and to take into account the virtual positronium formation. Using these approaches, we obtained numeric results that show strong variations in shape and magnitudes of scattering phases and cross sections due to effect of endohedral polarization and P˜s formation.

  16. Ultrasonic scattering and transmission properties of mammalian white matter in the detection of brain injury (United States)

    Mobley, Joel; Mathur, Anu N.; Vo-Dinh, Tuan


    In this work, we examine the orientation-dependent scattering and attenuation properties of white mater from mammalian brain tissue. We find that both the backscatter and attenuation of ultrasound in these tissues exhibit anisotropy. Furthermore, when extrapolated down to 1 MHz, it appears that the attenuation differences will be small but the backscatter differences are potentially resolvable. From a tissue characterization context, this means that the impact of changes due to the rotation of overlying tissues will be small compared to the changes in the strength of the backscatter signals from the regions of interest.

  17. Coherent anti-Stokes Raman scattering under electric field stimulation (United States)

    Capitaine, Erwan; Ould Moussa, Nawel; Louot, Christophe; Lefort, Claire; Pagnoux, Dominique; Duclère, Jean-René; Kaneyasu, Junya F.; Kano, Hideaki; Duponchel, Ludovic; Couderc, Vincent; Leproux, Philippe


    We introduce an experiment using electro-CARS, an electro-optical method based on the combination of ultrabroadband multiplex coherent anti-Stokes Raman scattering (M-CARS) spectroscopy and electric field stimulation. We demonstrate that this method can effectively discriminate the resonant CARS signal from the nonresonant background owing to a phenomenon of molecular orientation in the sample medium. Such molecular orientation is intrinsically related to the induction of an electric dipole moment by the applied static electric field. Evidence of the electro-CARS effect is obtained with a solution of n -alkanes (CnH2 n +2 , 15 ≤n ≤40 ), for which an enhancement of the CARS signal-to-noise ratio is achieved in the case of CH2 and CH3 symmetric/asymmetric stretching vibrations. Additionally, an electric-field-induced second-harmonic generation experiment is performed in order to corroborate the orientational organization of molecules due to the electric field excitation. Finally, we use a simple mathematical approach to compare the vibrational information extracted from electro-CARS measurements with spontaneous Raman data and to highlight the impact of electric stimulation on the vibrational signal.

  18. Determining Complex Structures using Docking Method with Single Particle Scattering Data

    Directory of Open Access Journals (Sweden)

    Haiguang Liu


    Full Text Available Protein complexes are critical for many molecular functions. Due to intrinsic flexibility and dynamics of complexes, their structures are more difficult to determine using conventional experimental methods, in contrast to individual subunits. One of the major challenges is the crystallization of protein complexes. Using X-ray free electron lasers (XFELs, it is possible to collect scattering signals from non-crystalline protein complexes, but data interpretation is more difficult because of unknown orientations. Here, we propose a hybrid approach to determine protein complex structures by combining XFEL single particle scattering data with computational docking methods. Using simulations data, we demonstrate that a small set of single particle scattering data collected at random orientations can be used to distinguish the native complex structure from the decoys generated using docking algorithms. The results also indicate that a small set of single particle scattering data is superior to spherically averaged intensity profile in distinguishing complex structures. Given the fact that XFEL experimental data are difficult to acquire and at low abundance, this hybrid approach should find wide applications in data interpretations.

  19. Determining Complex Structures using Docking Method with Single Particle Scattering Data. (United States)

    Wang, Hongxiao; Liu, Haiguang


    Protein complexes are critical for many molecular functions. Due to intrinsic flexibility and dynamics of complexes, their structures are more difficult to determine using conventional experimental methods, in contrast to individual subunits. One of the major challenges is the crystallization of protein complexes. Using X-ray free electron lasers (XFELs), it is possible to collect scattering signals from non-crystalline protein complexes, but data interpretation is more difficult because of unknown orientations. Here, we propose a hybrid approach to determine protein complex structures by combining XFEL single particle scattering data with computational docking methods. Using simulations data, we demonstrate that a small set of single particle scattering data collected at random orientations can be used to distinguish the native complex structure from the decoys generated using docking algorithms. The results also indicate that a small set of single particle scattering data is superior to spherically averaged intensity profile in distinguishing complex structures. Given the fact that XFEL experimental data are difficult to acquire and at low abundance, this hybrid approach should find wide applications in data interpretations.

  20. Light Scattering based detection of food pathogens (United States)

    The current methods for detecting foodborne pathogens are mostly destructive (i.e., samples need to be pretreated), and require time, personnel, and laboratories for analyses. Optical methods including light scattering based techniques have gained a lot of attention recently due to its their rapid a...

  1. Reproducibility of artificial multiple scattering media

    NARCIS (Netherlands)

    Marakis, Evangelos; van Harten, Wouter; Uppu, Ravitej; Pinkse, Pepijn Willemszoon Harry


    State of the art authentication systems depend on physical unclonable functions (PUF) [1], physical keys that are assumed unclonable due to technological constraints. Random scattering media, dielectric materials with rapid and random refractive index variations, are considered as ideal optical PUFs

  2. A model-based scatter artifacts correction for cone beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Wei; Zhu, Jun; Wang, Luyao [Department of Biomedical Engineering, Huazhong University of Science and Technology, Hubei 430074 (China); Vernekohl, Don; Xing, Lei, E-mail: [Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States)


    Purpose: Due to the increased axial coverage of multislice computed tomography (CT) and the introduction of flat detectors, the size of x-ray illumination fields has grown dramatically, causing an increase in scatter radiation. For CT imaging, scatter is a significant issue that introduces shading artifact, streaks, as well as reduced contrast and Hounsfield Units (HU) accuracy. The purpose of this work is to provide a fast and accurate scatter artifacts correction algorithm for cone beam CT (CBCT) imaging. Methods: The method starts with an estimation of coarse scatter profiles for a set of CBCT data in either image domain or projection domain. A denoising algorithm designed specifically for Poisson signals is then applied to derive the final scatter distribution. Qualitative and quantitative evaluations using thorax and abdomen phantoms with Monte Carlo (MC) simulations, experimental Catphan phantom data, and in vivo human data acquired for a clinical image guided radiation therapy were performed. Scatter correction in both projection domain and image domain was conducted and the influences of segmentation method, mismatched attenuation coefficients, and spectrum model as well as parameter selection were also investigated. Results: Results show that the proposed algorithm can significantly reduce scatter artifacts and recover the correct HU in either projection domain or image domain. For the MC thorax phantom study, four-components segmentation yields the best results, while the results of three-components segmentation are still acceptable. The parameters (iteration number K and weight β) affect the accuracy of the scatter correction and the results get improved as K and β increase. It was found that variations in attenuation coefficient accuracies only slightly impact the performance of the proposed processing. For the Catphan phantom data, the mean value over all pixels in the residual image is reduced from −21.8 to −0.2 HU and 0.7 HU for projection

  3. Scattering-initiated parametric noise in optical parametric chirped-pulse amplification. (United States)

    Wang, Jing; Ma, Jingui; Yuan, Peng; Tang, Daolong; Zhou, Binjie; Xie, Guoqiang; Qian, Liejia


    We experimentally study a new kind of parametric noise that is initiated from signal scattering and enhanced through optical parametric amplification. Such scattering-initiated parametric noise behaves similarly to parametric super-fluorescence in the spatial domain, yet is typically much stronger. In the time domain it inherits the chirp of signal pulses and can be well compressed. We demonstrate that scattering-initiated parametric noise has little influence on the pulse contrast but can degrade the energy conversion efficiency substantially.

  4. Retrieval of ozone profiles from GOMOS limb scattered measurements

    Directory of Open Access Journals (Sweden)

    S. Tukiainen


    Full Text Available The GOMOS (Global Ozone Monitoring by Occultation of Stars instrument on board the Envisat satellite measures the vertical composition of the atmosphere using the stellar occultation technique. While the night-time occultations of GOMOS have been proven to be of good quality, the daytime occultations are more challenging due to weaker signal-to-noise ratio. During daytime GOMOS measures limb scattered solar radiation in addition to stellar radiation. In this paper we introduce a retrieval method that determines ozone profiles between 20–60 km from GOMOS limb scattered solar radiances. GOMOS observations contain a considerable amount of stray light at high altitudes. We introduce a method for removing stray light and demonstrate its feasibility by comparing the corrected radiances against those measured by the OSIRIS (Optical Spectrograph & Infra Red Imaging System instrument. For the retrieval of ozone profiles, a standard onion peeling method is used. The first comparisons with other data sets suggest that the retrieved ozone profiles in 22–50 km are within 10% compared with the GOMOS night-time occultations and within 15% compared with OSIRIS. GOMOS has measured about 350 000 daytime profiles since 2002. The retrieval method presented here makes this large amount of data available for scientific use.

  5. Retrieval of ozone profiles from GOMOS limb scattered measurements (United States)

    Tukiainen, S.; Kyrölä, E.; Verronen, P. T.; Fussen, D.; Blanot, L.; Barrot, G.; Hauchecorne, A.; Lloyd, N.


    The GOMOS (Global Ozone Monitoring by Occultation of Stars) instrument on board the Envisat satellite measures the vertical composition of the atmosphere using the stellar occultation technique. While the night-time occultations of GOMOS have been proven to be of good quality, the daytime occultations are more challenging due to weaker signal-to-noise ratio. During daytime GOMOS measures limb scattered solar radiation in addition to stellar radiation. In this paper we introduce a retrieval method that determines ozone profiles between 20-60 km from GOMOS limb scattered solar radiances. GOMOS observations contain a considerable amount of stray light at high altitudes. We introduce a method for removing stray light and demonstrate its feasibility by comparing the corrected radiances against those measured by the OSIRIS (Optical Spectrograph & Infra Red Imaging System) instrument. For the retrieval of ozone profiles, a standard onion peeling method is used. The first comparisons with other data sets suggest that the retrieved ozone profiles in 22-50 km are within 10% compared with the GOMOS night-time occultations and within 15% compared with OSIRIS. GOMOS has measured about 350 000 daytime profiles since 2002. The retrieval method presented here makes this large amount of data available for scientific use.

  6. Pulsed holographic system for imaging through spatially extended scattering media (United States)

    Kanaev, A. V.; Judd, K. P.; Lebow, P.; Watnik, A. T.; Novak, K. M.; Lindle, J. R.


    Imaging through scattering media is a highly sought capability for military, industrial, and medical applications. Unfortunately, nearly all recent progress was achieved in microscopic light propagation and/or light propagation through thin or weak scatterers which is mostly pertinent to medical research field. Sensing at long ranges through extended scattering media, for example turbid water or dense fog, still represents significant challenge and the best results are demonstrated using conventional approaches of time- or range-gating. The imaging range of such systems is constrained by their ability to distinguish a few ballistic photons that reach the detector from the background, scattered, and ambient photons, as well as from detector noise. Holography can potentially enhance time-gating by taking advantage of extra signal filtering based on coherence properties of the ballistic photons as well as by employing coherent addition of multiple frames. In a holographic imaging scheme ballistic photons of the imaging pulse are reflected from a target and interfered with the reference pulse at the detector creating a hologram. Related approaches were demonstrated previously in one-way imaging through thin biological samples and other microscopic scale scatterers. In this work, we investigate performance of holographic imaging systems under conditions of extreme scattering (less than one signal photon per pixel signal), demonstrate advantages of coherent addition of images recovered from holograms, and discuss image quality dependence on the ratio of the signal and reference beam power.


    Directory of Open Access Journals (Sweden)

    S.Yu. Belov


    Full Text Available Monitoring of the earth’s surface by remote sensing in the short-wave band can provide quick identification of some characteristics of natural systems. This band range allows one to diagnose subsurface aspects of the earth, as the scattering parameter is affected by irregularities in the dielectric permittivity of subsurface structures. The new method is suggested. This method based on the organization of the monitoring probe may detect changes in these environments, for example, to assess seismic hazard, hazardous natural phenomena, changes ecosystems, as well as some man-made hazards and etc. The problem of measuring and accounting for the scattering power of the earth’s surface in the short-range of radio waves is important for a number of purposes, such as diagnosing properties of the medium, which is of interest for geological, environmental studies. In this paper, we propose a new method for estimating the parameters of incoherent signal/noise ratio. The paper presents the results of comparison of the measurement method from the point of view of their admissible relative analytical errors. A comparative analysis and shows that the analytical (relative accuracy of the determination of this parameter new method on the order exceeds the widely-used standard method. Analysis of admissible relative analytical error of estimation of this parameter allowed to recommend new method instead of standard method

  8. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael


    . In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus......We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...

  9. Electromagnetic scattering theory (United States)

    Bird, J. F.; Farrell, R. A.


    Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.

  10. 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...

  11. Λ scattering equations

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Humberto [Instituto de Fisica - Universidade de São Paulo,Caixa Postal 66318, 05315-970 São Paulo, SP (Brazil); Facultad de Ciencias Basicas, Universidad Santiago de Cali,Calle 5 62-00 Barrio Pampalinda, Cali, Valle (Colombia)


    The CHY representation of scattering amplitudes is based on integrals over the moduli space of a punctured sphere. We replace the punctured sphere by a double-cover version. The resulting scattering equations depend on a parameter Λ controlling the opening of a branch cut. The new representation of scattering amplitudes possesses an enhanced redundancy which can be used to fix, modulo branches, the location of four punctures while promoting Λ to a variable. Via residue theorems we show how CHY formulas break up into sums of products of smaller (off-shell) ones times a propagator. This leads to a powerful way of evaluating CHY integrals of generic rational functions, which we call the Λ algorithm.

  12. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael


    We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...


    Energy Technology Data Exchange (ETDEWEB)



    Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern

  14. Nanorough gold for enhanced Raman scattering. (United States)

    Kim, Jeonghwan; Kang, Kyung-Nam; Sarkar, Anirban; Malempati, Pallavi; Hah, Dooyoung; Daniels-Race, Theda; Feldman, Martin


    Conventional Raman scattering is a workhorse technique for detecting and identifying complex molecular samples. In surface enhanced Raman scattering, a nanorough metallic surface close to the sample enhances the Raman signal enormously. In this work, the surface is on a clear epoxy substrate. The epoxy is cast on a silicon wafer, using 20 nm of gold as a mold release. This single step process already produces useful enhanced Raman signals. However, the Raman signal is further enhanced by (1) depositing additional gold on the epoxy substrate and (2) by using a combination of wet and dry etches to roughen the silicon substrate before casting the epoxy. The advantage of a clear substrate is that the Raman signal may be obtained by passing light through the substrate, with opaque samples simply placed against the surface. Results were obtained with solutions of Rhodamine 6G in deionized water over a range of concentrations from 1 nM to 1 mM. In all cases, the signal to noise ratio was greater than 10:1.

  15. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)


    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  16. Realizing total reciprocity violation in the phase for photon scattering. (United States)

    Deák, László; Bottyán, László; Fülöp, Tamás; Merkel, Dániel Géza; Nagy, Dénes Lajos; Sajti, Szilárd; Schulze, Kai Sven; Spiering, Hartmut; Uschmann, Ingo; Wille, Hans-Christian


    Reciprocity is when wave or quantum scattering satisfies a symmetry property, connecting a scattering process with the reversed one. While reciprocity involves the interchange of source and detector, it is fundamentally different from rotational invariance, and is a generalization of time reversal invariance, occurring in absorptive media as well. Due to its presence at diverse areas of physics, it admits a wide variety of applications. For polarization dependent scatterings, reciprocity is often violated, but violation in the phase of the scattering amplitude is much harder to experimentally observe than violation in magnitude. Enabled by the advantageous properties of nuclear resonance scattering of synchrotron radiation, we have measured maximal, i.e., 180-degree, reciprocity violation in the phase. For accessing phase information, we introduced a new version of stroboscopic detection. The scattering setting was devised based on a generalized reciprocity theorem that opens the way to construct new types of reciprocity related devices.

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

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

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

  18. Intercomparison of gamma scattering, gammatography, and radiography techniques for mild steel nonuniform corrosion detection (United States)

    Priyada, P.; Margret, M.; Ramar, R.; Shivaramu, Menaka, M.; Thilagam, L.; Venkataraman, B.; Raj, Baldev


    This paper focuses on the mild steel (MS) corrosion detection and intercomparison of results obtained by gamma scattering, gammatography, and radiography techniques. The gamma scattering non-destructive evaluation (NDE) method utilizes scattered gamma radiation for the detection of corrosion, and the scattering experimental setup is an indigenously designed automated personal computer (PC) controlled scanning system consisting of computerized numerical control (CNC) controlled six-axis source detector system and four-axis job positioning system. The system has been successfully used to quantify the magnitude of corrosion and the thickness profile of a MS plate with nonuniform corrosion, and the results are correlated with those obtained from the conventional gammatography and radiography imaging measurements. A simple and straightforward reconstruction algorithm to reconstruct the densities of the objects under investigation and an unambiguous interpretation of the signal as a function of material density at any point of the thick object being inspected is described. In this simple and straightforward method the density of the target need not be known and only the knowledge of the target material's mass attenuation coefficients (composition) for the incident and scattered energies is enough to reconstruct the density of the each voxel of the specimen being studied. The Monte Carlo (MC) numerical simulation of the phenomena is done using the Monte Carlo N-Particle Transport Code (MCNP) and the quantitative estimates of the values of signal-to-noise ratio for different percentages of MS corrosion derived from these simulations are presented and the spectra are compared with the experimental data. The gammatography experiments are carried out using the same PC controlled scanning system in a narrow beam, good geometry setup, and the thickness loss is estimated from the measured transmitted intensity. Radiography of the MS plates is carried out using 160 kV x

  19. Study of erythrocyte membrane fluctuation using light scattering analysis (United States)

    Lee, Hoyoon; Lee, Sangyun; Park, YongKeun; Shin, Sehyun


    It is commonly known that alteration of erythrocyte deformability lead to serious microcirculatory diseases such as retinopathy, nephropathy, etc. Various methods and technologies have been developed to diagnose such membrane properties of erythrocytes. In this study, we developed an innovative method to measure hemorheological characteristics of the erythrocyte membrane using a light scattering analysis with simplified optic setting and multi-cell analysis as well. Light scattering intensity through multiple erythrocytes and its power density spectrum were obtained. The results of light scattering analyses were compared in healthy control and artificially hardened sample which was treated with glutaraldehyde. These results were further compared with conventional assays to measure deformable property in hemorheology. We found that light scattering information would reflect the disturbance of membrane fluctuation in artificially damaged erythrocytes. Therefore, measuring fluctuation of erythrocyte membrane using light scattering signal could facilitate simple and precise diagnose of pathological state on erythrocyte as well as related complications.

  20. Small Angle Neutron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Volker S [ORNL


    Small Angle Neutron Scattering (SANS) probes structural details at the nanometer scale in a non-destructive way. This article gives an introduction to scientists who have no prior small-angle scattering knowledge, but who seek a technique that allows elucidating structural information in challenging situations that thwart approaches by other methods. SANS is applicable to a wide variety of materials including metals and alloys, ceramics, concrete, glasses, polymers, composites and biological materials. Isotope and magnetic interactions provide unique methods for labeling and contrast variation to highlight specific structural features of interest. In situ studies of a material s responses to temperature, pressure, shear, magnetic and electric fields, etc., are feasible as a result of the high penetrating power of neutrons. SANS provides statistical information on significant structural features averaged over the probed sample volume, and one can use SANS to quantify with high precision the structural details that are observed, for example, in electron microscopy. Neutron scattering is non-destructive; there is no need to cut specimens into thin sections, and neutrons penetrate deeply, providing information on the bulk material, free from surface effects. The basic principles of a SANS experiment are fairly simple, but the measurement, analysis and interpretation of small angle scattering data involves theoretical concepts that are unique to the technique and that are not widely known. This article includes a concise description of the basics, as well as practical know-how that is essential for a successful SANS experiment.

  1. Critical fluid light scattering (United States)

    Gammon, Robert W.


    The objective is to measure the decay rates of critical density fluctuations in a simple fluid (xenon) very near its liquid-vapor critical point using laser light scattering and photon correlation spectroscopy. Such experiments were severely limited on Earth by the presence of gravity which causes large density gradients in the sample when the compressibility diverges approaching the critical point. The goal is to measure fluctuation decay rates at least two decades closer to the critical point than is possible on earth, with a resolution of 3 microK. This will require loading the sample to 0.1 percent of the critical density and taking data as close as 100 microK to the critical temperature. The minimum mission time of 100 hours will allow a complete range of temperature points to be covered, limited by the thermal response of the sample. Other technical problems have to be addressed such as multiple scattering and the effect of wetting layers. The experiment entails measurement of the scattering intensity fluctuation decay rate at two angles for each temperature and simultaneously recording the scattering intensities and sample turbidity (from the transmission). The analyzed intensity and turbidity data gives the correlation length at each temperature and locates the critical temperature. The fluctuation decay rate data from these measurements will provide a severe test of the generalized hydrodynamic theories of transport coefficients in the critical regions. When compared to equivalent data from binary liquid critical mixtures they will test the universality of critical dynamics.

  2. Inelastic magnon scattering

    Directory of Open Access Journals (Sweden)

    Robert de Mello Koch


    Full Text Available We study the worldsheet S-matrix of a string attached to a D-brane in AdS5×S5. The D-brane is either a giant graviton or a dual giant graviton. In the gauge theory, the operators we consider belong to the su(2|3 sector of the theory. Magnon excitations of open strings can exhibit both elastic (when magnons in the bulk of the string scatter and inelastic (when magnons at the endpoint of an open string participate scattering. Both of these S-matrices are determined (up to an overall phase by the su(2|22 global symmetry of the theory. In this note we study the S-matrix for inelastic scattering. We show that it exhibits poles corresponding to boundstates of bulk and boundary magnons. A crossing equation is derived for the overall phase. It reproduces the crossing equation for maximal giant gravitons, in the appropriate limit. Finally, scattering in the su(2 sector is computed to two loops. This two loop result, which determines the overall phase to two loops, will be useful when a unique solution to the crossing equation is to be selected.

  3. Inelastic magnon scattering (United States)

    de Mello Koch, Robert; van Zyl, Hendrik J. R.


    We study the worldsheet S-matrix of a string attached to a D-brane in AdS5 ×S5. The D-brane is either a giant graviton or a dual giant graviton. In the gauge theory, the operators we consider belong to the su (2 | 3) sector of the theory. Magnon excitations of open strings can exhibit both elastic (when magnons in the bulk of the string scatter) and inelastic (when magnons at the endpoint of an open string participate) scattering. Both of these S-matrices are determined (up to an overall phase) by the su(2 | 2) 2 global symmetry of the theory. In this note we study the S-matrix for inelastic scattering. We show that it exhibits poles corresponding to boundstates of bulk and boundary magnons. A crossing equation is derived for the overall phase. It reproduces the crossing equation for maximal giant gravitons, in the appropriate limit. Finally, scattering in the su (2) sector is computed to two loops. This two loop result, which determines the overall phase to two loops, will be useful when a unique solution to the crossing equation is to be selected.

  4. Photoacoustic Doppler flow measurement in optically scattering media


    Fang, Hui; Maslov, Konstantin; Wang, Lihong V.


    We recently observed the photoacoustic Doppler effect from flowing small light-absorbing particles. Here, we apply the effect to measure blood-mimicking fluid flow in an optically scattering medium. The light scattering in the medium decreases the amplitude of the photoacoustic Doppler signal but does not affect either the magnitude or the directional discrimination of the photoacoustic Doppler shift. This technology may hold promise for a new Doppler method for measuring blood flow in microc...

  5. Intrabeam scattering in the LHC

    CERN Document Server

    Mertens, Tom; Sousa Da Costa, Miguel


    Intrabeam Scattering (IBS) is the process where particles within an accelerator beam elastically scatter off each other. The effect of IBS is not to be confused with the Coulomb repulsion due to the fields generated by the other particles in the beam. The Coulomb repulsion effects are referred to as space-charge effects in Accelerator Physics and become less important than IBS at high energies because of the 1/gamma^2 that occurs in the space-charge equations making IBS one of the most important causes of beam size growth. At high energies (for example at 7 TeV or the LHC nominal operation energy) IBS effects are counteracted by Radiation Damping effects, in some cases leading to decrease in beam sizes instead of beam growth. But at the time of writing the operation energies were still low enough to neglect Radiation Damping Effects in comparison with IBS effects (Radiation Lifetimes were a factor five to ten higher than the IBS Lifetimes in the cases presented at the end of this text). Because of its effect ...

  6. Small angle neutron scattering

    Directory of Open Access Journals (Sweden)

    Cousin Fabrice


    Full Text Available Small Angle Neutron Scattering (SANS is a technique that enables to probe the 3-D structure of materials on a typical size range lying from ∼ 1 nm up to ∼ a few 100 nm, the obtained information being statistically averaged on a sample whose volume is ∼ 1 cm3. This very rich technique enables to make a full structural characterization of a given object of nanometric dimensions (radius of gyration, shape, volume or mass, fractal dimension, specific area… through the determination of the form factor as well as the determination of the way objects are organized within in a continuous media, and therefore to describe interactions between them, through the determination of the structure factor. The specific properties of neutrons (possibility of tuning the scattering intensity by using the isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons make it particularly interesting in the fields of soft matter, biophysics, magnetic materials and metallurgy. In particular, the contrast variation methods allow to extract some informations that cannot be obtained by any other experimental techniques. This course is divided in two parts. The first one is devoted to the description of the principle of SANS: basics (formalism, coherent scattering/incoherent scattering, notion of elementary scatterer, form factor analysis (I(q→0, Guinier regime, intermediate regime, Porod regime, polydisperse system, structure factor analysis (2nd Virial coefficient, integral equations, characterization of aggregates, and contrast variation methods (how to create contrast in an homogeneous system, matching in ternary systems, extrapolation to zero concentration, Zero Averaged Contrast. It is illustrated by some representative examples. The second one describes the experimental aspects of SANS to guide user in its future experiments: description of SANS spectrometer, resolution of the spectrometer, optimization of

  7. Simple and Efficient Decoupling of Compact Arrays With Parasitic Scatterers

    DEFF Research Database (Denmark)

    Lau, B.K.; Andersen, Jørgen Bach


    Compact arrays such as multiple antennas on a mobile terminal suffer from low efficiency and high correlation between antenna signals. In the present paper, a simple and rigorous procedure for decoupling two closely coupled antennas with a parasitic scatterer is proposed. The parasitic scatterer......, which can be an additional antenna, acts as a shield between two active antenna elements. In contrast to previous studies involving the use of parasitic scatterer for decoupling antennas, we demonstrate using antenna impedances the underlying decoupling mechanism for two arbitrary antennas. By a proper...

  8. Backward elastic light scattering of malaria infected red blood cells (United States)

    Lee, Seungjun; Lu, Wei


    We investigated the backward light scattering pattern of healthy and malaria (Plasmodium falciparum) parasitized red blood cells. The spectrum could clearly distinguish between predominant ring stage infected blood cells and healthy blood cells. Further, we found that infected samples mixed with different stages of P. falciparum showed different signals, suggesting that even variance in parasite stages could also be detected by the spectrum. These results together with the backward scattering technique suggest the potential of non-invasive diagnosis of malaria through light scattering of blood cells near the surface of human body, such as using eyes or skin surface.

  9. Numerical modelling of multiple scattering between two elastical particles

    DEFF Research Database (Denmark)

    Bjørnø, Irina; Jensen, Leif Bjørnø


    is higher than 20 g/l of sand particles. This paper reports an attempt to illuminate and to solve the proximity threshold question, by an in-depth numerical study of the interaction of ultrasonic signals with two canonically shaped elastic particles. Introductory experimental results seem to create evidence...... for the applicability of this new numerical model...... 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...

  10. Progress report on neutron scattering at JAERI

    Energy Technology Data Exchange (ETDEWEB)

    Morii, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    In the first half of fiscal year 1997, JRR-3M was operated for 97 days followed by a long term shut down for its annual maintenance. Three days were lost out of 100 scheduled operation days, due to a trouble in irradiation facility. Neutron scattering research activities at the JRR-3M have been extended from that of fiscal year 1996. In the Research Group for Quantum Condensed Matter System, experimental study under high pressures, low temperatures and high fields as well as coupling of these conditions were planned to find new quantum condensed matter systems. And, obtained experimental results were immediately provided to theorists for their investigations. In cooperation with new group, Research Group for Neutron Scattering of Strongly Correlated Electron Systems and Research Group for Neutron Scattering at Ultralow Temperatures were carrying neutron scattering experiments at JRR-3M. Research Group for Neutron Crystallography in Biology had opened a way for investigating biomatter neutron diffraction research with high experimental accuracy by growing a millimeter-class large single crystal. In fiscal year 1997, 39 research projects were conducted by these four groups and other staffs in JAERI, 27 projects collaborated with university researchers and 3 projects collaborated with private enterprises were also conducted as complementary researches. 2117 days of machine times were requested to use 8 neutron scattering instruments this year, which corresponded to 1.51 times larger than those planned at its beginning. (G.K.)

  11. Rayleigh's Scattering Revised (United States)

    Kolomiets, Sergey; Gorelik, Andrey

    This report is devoted to a discussion of applicability limits of Rayleigh’s scattering model. Implicitly, Rayleigh’s ideas are being used in a wide range of remote sensing applications. To begin with it must be noted that most techniques which have been developed to date for measurements by means of active instruments for remote sensing in case of the target is a set of distributed moving scatters are only hopes, to say so, on measurements per se. The problem is that almost all of such techniques use a priori information about the microstructure of the object of interest during whole measurement session. As one can find in the literature, this approach may happily be applied to systems with identical particles. However, it is not the case with respect to scattering targets that consist of particles of different kind or having a particle size distribution. It must be especially noted that the microstructure of most of such targets changes significantly with time and/or space. Therefore, the true measurement techniques designed to be applicable in such conditions must be not only adaptable in order to take into account a variety of models of an echo interpretation, but also have a well-developed set of clear-cut criteria of applicability and exact means of accuracy estimation. So such techniques will require much more parameters to be measured. In spite of the fact that there is still room for some improvements within classical models and approaches, it is multiwavelength approach that may be seen as the most promising way of development towards obtaining an adequate set of the measured parameters required for true measurement techniques. At the same time, Rayleigh’s scattering is an invariant in regard to a change of the wavelength as it follows from the point of view dominating nowadays. In the light of such an idea, the synergy between multivawelength measurements may be achieved - to a certain extent - by means of the synchronous usage of Rayleigh’s and

  12. Light scattering reviews 8 radiative transfer and light scattering

    CERN Document Server

    Kokhanovsky, Alexander A


    Light scattering review (vol 8) is aimed at the presentation of recent advances in radiative transfer and light scattering optics. The topics to be covered include: scattering of light by irregularly shaped particles suspended in atmosphere (dust, ice crystals), light scattering by particles much larger as compared the wavelength of incident radiation, atmospheric radiative forcing, astrophysical radiative transfer, radiative transfer and optical imaging in biological media, radiative transfer of polarized light, numerical aspects of radiative transfer.

  13. FDTD scattered field formulation for scatterers in stratified dispersive media. (United States)

    Olkkonen, Juuso


    We introduce a simple scattered field (SF) technique that enables finite difference time domain (FDTD) modeling of light scattering from dispersive objects residing in stratified dispersive media. The introduced SF technique is verified against the total field scattered field (TFSF) technique. As an application example, we study surface plasmon polariton enhanced light transmission through a 100 nm wide slit in a silver film.

  14. Patient-specific scatter correction in clinical cone beam computed tomography imaging made possible by the combination of Monte Carlo simulations and a ray tracing algorithm

    DEFF Research Database (Denmark)

    Slot Thing, Rune; Bernchou, Uffe; Mainegra-Hing, Ernesto


    _cbct), was used to perform MC simulations of an Elekta XVI CBCT imaging system. A 60keV x-ray source was used, and air kerma scored at the detector plane. Several variance reduction techniques (VRTs) were used to increase the scatter calculation efficiency. Three patient phantoms based on CT scans were simulated...... being fully implemented in a clinical setting. This study investigates the combination of using fast MC simulations to predict scatter distributions with a ray tracing algorithm to allow calibration between simulated and clinical CBCT images. Material and methods. An EGSnrc-based user code (egs......, namely a brain, a thorax and a pelvis scan. A ray tracing algorithm was used to calculate the detector signal due to primary photons. A total of 288 projections were simulated, one for each thread on the computer cluster used for the investigation. Results. Scatter distributions for the brain, thorax...

  15. Three-dimensional imaging of absolute blood flow velocity and blood vessel position under low blood flow velocity based on Doppler signal information included in scattered light from red blood cells (United States)

    Kyoden, Tomoaki; Akiguchi, Shunsuke; Tajiri, Tomoki; Andoh, Tsugunobu; Hachiga, Tadashi


    The development of a system for in vivo visualization of occluded distal blood vessels for diabetic patients is the main target of our research. We herein describe two-beam multipoint laser Doppler velocimetry (MLDV), which measures the instantaneous multipoint flow velocity and can be used to observe the blood flow velocity in peripheral blood vessels. By including a motorized stage to shift the measurement points horizontally and in the depth direction while measuring the velocity, the path of the blood vessel in the skin could be observed using blood flow velocity in three-dimensional space. The relationship of the signal power density between the blood vessel and the surrounding tissues was shown and helped us identify the position of the blood vessel. Two-beam MLDV can be used to simultaneously determine the absolute blood flow velocity distribution and identify the blood vessel position in skin.

  16. Electromagnetic scattering from random media

    CERN Document Server

    Field, Timothy R


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

  17. Enhanced incoherent scatter plasma lines

    Directory of Open Access Journals (Sweden)

    H. Nilsson

    Full Text Available Detailed model calculations of auroral secondary and photoelectron distributions for varying conditions have been used to calculate the theoretical enhancement of incoherent scatter plasma lines. These calculations are compared with EISCAT UHF radar measurements of enhanced plasma lines from both the E and F regions, and published EISCAT VHF radar measurements. The agreement between the calculated and observed plasma line enhancements is good. The enhancement from the superthermal distribution can explain even the very strong enhancements observed in the auroral E region during aurora, as previously shown by Kirkwood et al. The model calculations are used to predict the range of conditions when enhanced plasma lines will be seen with the existing high-latitude incoherent scatter radars, including the new EISCAT Svalbard radar. It is found that the detailed structure, i.e. the gradients in the suprathermal distribution, are most important for the plasma line enhancement. The level of superthermal flux affects the enhancement only in the region of low phase energy where the number of thermal electrons is comparable to the number of suprathermal electrons and in the region of high phase energy where the suprathermal fluxes fall to such low levels that their effect becomes small compared to the collision term. To facilitate the use of the predictions for the different radars, the expected signal- to-noise ratios (SNRs for typical plasma line enhancements have been calculated. It is found that the high-frequency radars (Søndre Strømfjord, EISCAT UHF should observe the highest SNR, but only for rather high plasma frequencies. The VHF radars (EISCAT VHF and Svalbard will detect enhanced plasma lines over a wider range of frequencies, but with lower SNR.

  18. Super-virtual Interferometric Separation and Enhancement of Back-scattered Surface Waves

    KAUST Repository

    Guo, Bowen


    Back-scattered surface waves can be migrated to detect near-surface reflectors with steep dips. A robust surface-wave migration requires the prior separation of the back-scattered surface-wave events from the data. This separation is often difficult to implement because the back-scattered surface waves are masked by the incident surface waves. We mitigate this problem by using a super-virtual interferometric method to enhance and separate the back-scattered surface waves. The key idea is to calculate the virtual back-scattered surface waves by stacking the resulting virtual correlated and convolved traces associated with the incident and back-scattered waves. Stacking the virtual back-scattered surface waves improves their signal-to-noise ratio and separates the back-scattered surface-waves from the incident field. Both synthetic and field data results validate the robustness of this method.

  19. DaMaSCUS: the impact of underground scatterings on direct detection of light dark matter (United States)

    Emken, Timon; Kouvaris, Chris


    Conventional dark matter direct detection experiments set stringent constraints on dark matter by looking for elastic scattering events between dark matter particles and nuclei in underground detectors. However these constraints weaken significantly in the sub-GeV mass region, simply because light dark matter does not have enough energy to trigger detectors regardless of the dark matter-nucleon scattering cross section. Even if future experiments lower their energy thresholds, they will still be blind to parameter space where dark matter particles interact with nuclei strongly enough that they lose enough energy and become unable to cause a signal above the experimental threshold by the time they reach the underground detector. Therefore in case dark matter is in the sub-GeV region and strongly interacting, possible underground scatterings of dark matter with terrestrial nuclei must be taken into account because they affect significantly the recoil spectra and event rates, regardless of whether the experiment probes DM via DM-nucleus or DM-electron interaction. To quantify this effect we present the publicly available Dark Matter Simulation Code for Underground Scatterings (DaMaSCUS), a Monte Carlo simulator of DM trajectories through the Earth taking underground scatterings into account. Our simulation allows the precise calculation of the density and velocity distribution of dark matter at any detector of given depth and location on Earth. The simulation can also provide the accurate recoil spectrum in underground detectors as well as the phase and amplitude of the diurnal modulation caused by this shadowing effect of the Earth, ultimately relating the modulations expected in different detectors, which is important to decisively conclude if a diurnal modulation is due to dark matter or an irrelevant background.

  20. Mode-converted ultrasonic scattering in polycrystals with elongated grains. (United States)

    Arguelles, Andrea P; Kube, Christopher M; Hu, Ping; Turner, Joseph A


    Elastic wave scattering is used to study polycrystalline media for a wide range of applications. Received signals, which include scattering from the randomly oriented grains comprising the polycrystal, contain information from which useful microstructural parameters may often be inferred. Recently, a mode-converted diffuse ultrasonic scattering model was developed for evaluating the scattered response of a transverse wave from an incident longitudinal wave in a polycrystalline medium containing equiaxed single-phase grains with cubic elastic symmetry. In this article, that theoretical mode-converted scattering model is modified to account for grain elongation within the sample. The model shows the dependence on scattering angle relative to the grain axis orientation. Experimental measurements were performed on a sample of 7475-T7351 aluminum using a pitch-catch transducer configuration. The results show that the mode-converted scattering can be used to determine the dimensions of the elongated grains. The average grain shape determined from the experimental measurements is compared with dimensions extracted from electron backscatter diffraction, an electron imaging technique. The results suggest that mode-converted diffuse ultrasonic scattering has the potential to quantify detailed information about grain microstructure.

  1. Electron scattering for exotic nuclei

    Indian Academy of Sciences (India)


    Nov 4, 2014 ... A brand-new electron scattering facility, the SCRIT Electron Scattering Facility, will soon start its operation at RIKEN RI Beam Factory, Japan. This is the world's first electron scattering facility dedicated to the structure studies of short-lived nuclei. The goal of this facility is to determine the charge density ...

  2. Double parton scattering theory overview

    NARCIS (Netherlands)

    Diehl, Markus; Gaunt, Jonathan R.


    The dynamics of double hard scattering in proton-proton collisions is quite involved compared with the familiar case of single hard scattering. In this contribution, we review our theoretical understanding of double hard scattering and of its interplay with other reaction mechanisms.

  3. Scattering problems in elastodynamics

    CERN Document Server

    Diatta, Andre; Wegener, Martin; Guenneau, Sebastien


    In electromagnetism, acoustics, and quantum mechanics, scattering problems can routinely be solved numerically by virtue of perfectly matched layers (PMLs) at simulation domain boundaries. Unfortunately, the same has not been possible for general elastodynamic wave problems in continuum mechanics. In this paper, we introduce a corresponding scattered-field formulation for the Navier equation. We derive PMLs based on complex-valued coordinate transformations leading to Cosserat elasticity-tensor distributions not obeying the minor symmetries. These layers are shown to work in two dimensions, for all polarizations, and all directions. By adaptative choice of the decay length, the deep subwavelength PMLs can be used all the way to the quasi-static regime. As demanding examples, we study the effectiveness of cylindrical elastodynamic cloaks of the Cosserat type and approximations thereof.

  4. Molecular-beam scattering

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, M.F.


    The molecular-beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces. Chapter 1 reports results of a low-energy (0.2 kcal/mole) elastic-scattering study of the He-Ar pair potential. The purpose of the study was to accurately characterize the shape of the potential in the well region, by scattering slow He atoms produced by expanding a mixture of He in N/sub 2/ from a cooled nozzle. Chapter 2 contains measurements of the vibrational predissociation spectra and product translational energy for clusters of water, benzene, and ammonia. The experiments show that most of the product energy remains in the internal molecular motions. Chapter 3 presents measurements of the reaction Na + HCl ..-->.. NaCl + H at collision energies of 5.38 and 19.4 kcal/mole. This is the first study to resolve both scattering angle and velocity for the reaction of a short lived (16 nsec) electronic excited state. Descriptions are given of computer programs written to analyze molecular-beam expansions to extract information characterizing their velocity distributions, and to calculate accurate laboratory elastic-scattering differential cross sections accounting for the finite apparatus resolution. Experimental results which attempted to determine the efficiency of optically pumping the Li(2/sup 2/P/sub 3/2/) and Na(3/sup 2/P/sub 3/2/) excited states are given. A simple three-level model for predicting the steady-state fraction of atoms in the excited state is included.

  5. Means on scattered compacta

    Czech Academy of Sciences Publication Activity Database

    Banakh, T.; Bonnet, R.; Kubiś, Wieslaw


    Roč. 2, č. 1 (2014), s. 5-10 ISSN 2299-3231 R&D Projects: GA ČR(CZ) GAP201/12/0290 Institutional support: RVO:67985840 Keywords : scattered compact space * mean operation Subject RIV: BA - General Mathematics xml

  6. K sup + - scattering

    CERN Document Server

    Farhan, A M


    A prescription is given to construct an effective interaction that may describe the scattering of K sup + by spin-zero nuclei in a more reliable way. This prescription is based on the Lorentz invariant representation of the meson-nucleon amplitude and the use of the Klein-Gordon equation of motion. Good results for K sup + - sup 1 sup 2 C as well as K sup + - D total cross sections at various energies have been obtained. (author)

  7. Electromagnetic wave dynamics in matter-wave superradiant scattering. (United States)

    Deng, L; Payne, M G; Hagley, E W


    We present a small-signal wave propagation theory on matter-wave superradiant scattering. We show, in a longitudinally excited condensate, that the backward-propagating, superradiantly generated optical field propagates with ultraslow group velocity and that the small-signal gain profile has a Bragg resonance. We further show a unidirectional suppression of optical superradiant scattering, and explain why matter-wave superradiance can occur only when the pump laser is red detuned. This is the first analytical theory on field propagation in matter-wave superradiance that can explain all matter-wave superradiance experiments to date that used a single-frequency, long-pulse, red-detuned laser.

  8. A multi-dimensional sampling method for locating small scatterers (United States)

    Song, Rencheng; Zhong, Yu; Chen, Xudong


    A multiple signal classification (MUSIC)-like multi-dimensional sampling method (MDSM) is introduced to locate small three-dimensional scatterers using electromagnetic waves. The indicator is built with the most stable part of signal subspace of the multi-static response matrix on a set of combinatorial sampling nodes inside the domain of interest. It has two main advantages compared to the conventional MUSIC methods. First, the MDSM is more robust against noise. Second, it can work with a single incidence even for multi-scatterers. Numerical simulations are presented to show the good performance of the proposed method.

  9. Neutron scattering in Australia

    Energy Technology Data Exchange (ETDEWEB)

    Knott, R.B. [Australian Nuclear Science and Technology Organisation, Menai (Australia)


    Neutron scattering techniques have been part of the Australian scientific research community for the past three decades. The High Flux Australian Reactor (HIFAR) is a multi-use facility of modest performance that provides the only neutron source in the country suitable for neutron scattering. The limitations of HIFAR have been recognized and recently a Government initiated inquiry sought to evaluate the future needs of a neutron source. In essence, the inquiry suggested that a delay of several years would enable a number of key issues to be resolved, and therefore a more appropriate decision made. In the meantime, use of the present source is being optimized, and where necessary research is being undertaken at major overseas neutron facilities either on a formal or informal basis. Australia has, at present, a formal agreement with the Rutherford Appleton Laboratory (UK) for access to the spallation source ISIS. Various aspects of neutron scattering have been implemented on HIFAR, including investigations of the structure of biological relevant molecules. One aspect of these investigations will be presented. Preliminary results from a study of the interaction of the immunosuppressant drug, cyclosporin-A, with reconstituted membranes suggest that the hydrophobic drug interdigitated with lipid chains.

  10. Scattering and; Delay, Scale, and Sum Migration

    Energy Technology Data Exchange (ETDEWEB)

    Lehman, S K


    the direction of arrival of a signal, and seismic migration in which wide band time series are shifted but not to form images per se. Section 3 presents a mostly graphically-based motivation and summary of delay, scale, and sum beamforming. The model for incident field propagation in free space is derived in Section 4 under specific assumptions. General object scattering is derived in Section 5 and simplified under the Born approximation in Section 6. The model of this section serves as the basis in the derivation of time-domain migration. The Foldy-Lax, full point scatterer scattering, method is derived in Section 7. With the previous forward models in hand, delay, scale, and sum beamforming is derived in Section 8. Finally, proof-of-principle experiments are present in Section 9.

  11. Diffusive scattering of electrons by electron holes around injection fronts (United States)

    Vasko, I. Y.; Agapitov, O. V.; Mozer, F. S.; Artemyev, A. V.; Krasnoselskikh, V. V.; Bonnell, J. W.


    Van Allen Probes have detected nonlinear electrostatic spikes around injection fronts in the outer radiation belt. These spikes include electron holes (EH), double layers, and more complicated solitary waves. We show that EHs can efficiently scatter electrons due to their substantial transverse electric fields. Although the electron scattering driven by EHs is diffusive, it cannot be evaluated via the standard quasi-linear theory. We derive analytical formulas describing local electron scattering by a single EH and verify them via test particle simulations. We show that the most efficiently scattered are gyroresonant electrons (crossing EH on a time scale comparable to the local electron gyroperiod). We compute bounce-averaged diffusion coefficients and demonstrate their dependence on the EH spatial distribution (latitudinal extent and spatial filling factor) and individual EH parameters (amplitude of electrostatic potential, velocity, and spatial scales). We show that EHs can drive pitch angle scattering of ≲5 keV electrons at rates 10-2-10-4 s-1 and, hence, can contribute to electron losses and conjugated diffuse aurora brightenings. The momentum and pitch angle scattering rates can be comparable, so that EHs can also provide efficient electron heating. The scattering rates driven by EHs at L shells L ˜ 5-8 are comparable to those due to chorus waves and may exceed those due to electron cyclotron harmonics.

  12. Plasma scattering of electromagnetic radiation

    CERN Document Server

    Sheffield, John


    Plasma Scattering of Electromagnetic Radiation covers the theory and experimental application of plasma scattering. The book discusses the basic properties of a plasma and of the interaction of radiation with a plasma; the relationship between the scattered power spectrum and the fluctuations in plasma density; and the incoherent scattering of low-temperature plasma. The text also describes the constraints and problems that arise in the application of scattering as a diagnostic technique; the characteristic performance of various dispersion elements, image dissectors, and detectors; and the ge

  13. Rational design of Raman-labeled nanoparticles for a dual-modality, light scattering immunoassay on a polystyrene substrate. (United States)

    Israelsen, Nathan D; Wooley, Donald; Hanson, Cynthia; Vargis, Elizabeth


    Surface-enhanced Raman scattering (SERS) is a powerful light scattering technique that can be used for sensitive immunoassay development and cell labeling. A major obstacle to using SERS is the complexity of fabricating SERS probes since they require nanoscale characterization and optical uniformity. The light scattering response of SERS probes may also be modulated by the substrate used for SERS analysis. A typical SERS substrate such as quartz can be expensive. Polystyrene is a cheaper substrate option but can decrease the SERS response due to interfering Raman emission peaks and high background fluorescence. The goal of this research is to develop an optimized process for fabricating Raman-labeled nanoparticles for a SERS-based immunoassay on a polystyrene substrate. We have developed a method for fabricating SERS nanoparticle probes for use in a light scattering immunoassay on a polystyrene substrate. The light scattering profile of both spherical gold nanoparticle and gold nanorod SERS probes were characterized using Raman spectroscopy and optical absorbance spectroscopy. The effects of substrate interference and autofluorescence were reduced by selecting a Raman reporter with a strong light scattering response in a spectral region where interfering substrate emission peaks are minimized. Both spherical gold nanoparticles and gold nanorods SERS probes used in the immunoassay were detected at labeling concentrations in the low pM range. This analytical sensitivity falls within the typical dynamic range for direct labeling of cell-surface biomarkers using SERS probes. SERS nanoparticle probes were fabricated to produce a strong light scattering signal despite substrate interference. The optical extinction and inelastic light scattering of these probes was detected by optical absorbance spectroscopy and Raman spectroscopy, respectively. This immunoassay demonstrates the feasibility of analyzing strongly enhanced Raman signals on polystyrene, which is an

  14. Influence of X-ray scatter radiation on image quality in Digital Breast Tomosynthesis (DBT) (United States)

    Rodrigues, M. J.; Di Maria, S.; Baptista, M.; Belchior, A.; Afonso, J.; Venâncio, J.; Vaz, P.


    Digital breast tomosynthesis (DBT) is a quasi-three-dimensional imaging technique that was developed to solve the principal limitation of mammography, namely the overlapping tissue effect. This issue in standard mammography (SM) leads to two main problems: low sensitivity (difficulty to detect lesions) and low specificity (non-negligible percentage of false positives). Although DBT is now being introduced in clinical practice the features of this technique have not yet been fully and accurately assessed. Consequently, optimization studies in terms of choosing the most suitable parameters which maximize image quality according to the known limits of breast dosimetry are currently performing. In DBT, scatter radiation can lead to a loss of contrast and to an increase of image noise by reducing the signal-to-difference-noise ratio (SDNR) of a lesion. Moreover the use of an anti-scatter grid is a concern due to the low exposure of the photon flux available per projection. For this reason the main aim of this study was to analyze the influence of the scatter radiation on image quality and the dose delivered to the breast. In particular a detailed analysis of the scatter radiation on the optimal energy that maximizes the SDNR was performed for different monochromatic energies and voltages. To reach this objective the PenEasy Monte Carlo (MC) simulation tool imbedded in the general-purpose main program PENELOPE, was used. After a successful validation of the MC model with measurements, 2D projection images of primary, coherent and incoherent photons were obtained. For that, a homogeneous breast phantom (2, 4, 6, 8 cm) with 25%, 50% and 75% glandular compositions was used, including a 5 mm thick tumor. The images were generated for each monochromatic X-ray energies in the range from 16 keV to 32 keV. For each angular projection considered (25 angular projections covering an arc of 50°) the scatter-to-primary ratio (SPR), the mean glandular dose (MGD) and the signal

  15. Gravitational scattering of electromagnetic radiation (United States)

    Brooker, J. T.; Janis, A. I.


    The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.

  16. Impurity Scattering and Mott's Formula in Graphene


    Lofwander, Tomas; Fogelstrom, Mikael


    We present calculations of the thermal and electric linear response in graphene, including disorder in the self-consistent t-matrix approximation. For strong impurity scattering, near the unitary limit, the formation of a band of impurity states near the Fermi level leads to that Mott's relation holds at low temperature. For higher temperatures, there are strong deviations due to the linear density of states. The low-temperature thermopower is proportional to the inverse of the impurity poten...

  17. Spatially distinct Raman scattering characteristics of individual ZnO nanorods under controlled polarization: intense end scattering from forbidden modes. (United States)

    Hansen, Matthew; Truong, Johnson; Xie, Tian; Hahm, Jong-In


    In this study, we characterize incident/scattered polarization-specific and NR position-resolved Raman scattering behaviors of individual zinc oxide nanorods (ZnO NRs). We quantify Raman signals from the five key ZnO phonon modes of E2L, E2H-2L, A1T, E1T, and E2H, and reveal the NR position-dependent Raman scattering characteristics of the phonon modes per given light-matter interaction geometry. We then present Raman intensity maps and elucidate Raman behaviors consistent and incongruous with Raman selection rules. In particular, we identify an intriguing Raman scattering phenomenon from the forbidden modes, distinctively occurring at the two NR ends. Their unexpectedly strong and localized scattering signals at the NR termini are contrasted by the scattering behaviors from the rest of the NR positions agreeing with the selection predictions. By carrying out control measurements on isotropic ZnO microparticles (MPs), we ascertain that the unique NR position-specific Raman responses observed on ZnO NRs originate from their high shape anisotropy. Owing to the superior optical property coupled with reduced dimensionality and high geometric anisotropy, ZnO NRs have gained much attention recently for use in optoelectronic, photonic, and biosensor technologies. Raman scattering has been increasingly exploited as a noninvasive and sensitive analytical tool to investigate NR properties pertinent to these applications. Hence, our endeavors, explicitly providing the spatially distinct, polarized Raman scattering behaviors from individual ZnO NRs, will be central to the correct interpretation of Raman data of both the individual and ensemble NRs as well as to the accurate correlation of the measurement outcomes to their chemical/physical/optical properties. Our efforts may also promote novel applications for polarized Raman scattering whose optical outputs on the various positions along the ZnO NRs can be selectively modulated.

  18. Interactive directional subsurface scattering and transport of emergent light

    DEFF Research Database (Denmark)

    Dal Corso, Alessandro; Frisvad, Jeppe Revall; Mosegaard, Jesper


    need to store elements of irradiance from specific directions. To include changes in subsurface scattering due to changes in the direction of the incident light, we instead sample incident radiance and store scattered radiosity. This enables us to accommodate not only the common distance......-based analytical models for subsurface scattering but also directional models. In addition, our method enables easy extraction of virtual point lights for transporting emergent light to the rest of the scene. Our method requires neither preprocessing nor texture parameterization of the translucent objects....... To build our maps of scattered radiosity, we progressively render the model from different directions using an importance sampling pattern based on the optical properties of the material. We obtain interactive frame rates, our subsurface scattering results are close to ground truth, and our technique...

  19. Scattering cross section of unequal length dipole arrays

    CERN Document Server

    Singh, Hema; Jha, Rakesh Mohan


    This book presents a detailed and systematic analytical treatment of scattering by an arbitrary dipole array configuration with unequal-length dipoles, different inter-element spacing and load impedance. It provides a physical interpretation of the scattering phenomena within the phased array system. The antenna radar cross section (RCS) depends on the field scattered by the antenna towards the receiver. It has two components, viz. structural RCS and antenna mode RCS. The latter component dominates the former, especially if the antenna is mounted on a low observable platform. The reduction in the scattering due to the presence of antennas on the surface is one of the concerns towards stealth technology. In order to achieve this objective, a detailed and accurate analysis of antenna mode scattering is required. In practical phased array, one cannot ignore the finite dimensions of antenna elements, coupling effect and the role of feed network while estimating the antenna RCS. This book presents the RCS estimati...

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

    Ahmadi, Farzad; Ida, Nathan


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

  1. Enhanced optical coupling and Raman scattering via microscopic interface engineering (United States)

    Thompson, Jonathan V.; Hokr, Brett H.; Kim, Wihan; Ballmann, Charles W.; Applegate, Brian E.; Jo, Javier A.; Yamilov, Alexey; Cao, Hui; Scully, Marlan O.; Yakovlev, Vladislav V.


    Spontaneous Raman scattering is an extremely powerful tool for the remote detection and identification of various chemical materials. However, when those materials are contained within strongly scattering or turbid media, as is the case in many biological and security related systems, the sensitivity and range of Raman signal generation and detection is severely limited. Here, we demonstrate that through microscopic engineering of the optical interface, the optical coupling of light into a turbid material can be substantially enhanced. This improved coupling facilitates the enhancement of the Raman scattering signal generated by molecules within the medium. In particular, we detect at least two-orders of magnitude more spontaneous Raman scattering from a sample when the pump laser light is focused into a microscopic hole in the surface of the sample. Because this approach enhances both the interaction time and interaction region of the laser light within the material, its use will greatly improve the range and sensitivity of many spectroscopic techniques, including Raman scattering and fluorescence emission detection, inside highly scattering environments.

  2. The Inclusion of Raman Scattering Effects in the Combined Ocean-Atmosphere Radiative Transfer Model MOMO to Estimate the Influence of Raman Scattering in Case 1 Waters on Satellite Ocean Remote Sensing Applications (United States)

    von Bismarck, J.; Fischer, J.


    Raman scattering of the solar lightfield, due to energy absorption by vibrational modes of water molecules, may contribute significantly to the signals observed by remote sensing satellites over water. The inelastic fraction of the water-leaving radiance for clear water reaches values of 30% in the red part of the visible spectrum, and still reaches values of several percent in moderately turbid waters. Furthermore, inelastic scattering due to chlorophyll and yellow substance fluorescence adds to this fraction. For these reasons the inclusion of inelastic scattering sources into radiative-transfer models, used in ocean remote sensing applications or atmosphere remote sensing over the ocean, can be important. MOMO is a computer code based on the matrix-operator method designed to calculate the lightfield in the stratified atmosphere-ocean system. It has been developed at the Institute for Space Sciences of the Freie Universität Berlin and provides the full polarization state (in the newest version) and an air-sea interface accounting for radiative effects of the wind roughened water surface. The inclusion of Raman scattering effects is done by a processing module, that starts a primary MOMO program run with a high spectral resolution, to calculate the radiative energy available for inelastic scattering at each model layer boundary. The processing module then calculates the first order Raman source-terms for every observation wavelength at every layer boundary, accounting for the non-isotropicity (including the azimuthal dependence) of the Raman phase-function, the spectral redistribution, and the spectral dependence of the Raman scattering coefficient. These elementary source-terms then serve as input for the second program run, which then calculates the source-terms of all model layers, using the doubling-adding method, and the resulting radiance field. Higher orders of the Raman contribution can be computed with additional program runs. Apart from the Raman

  3. Matched, mismatched, and robust scatter matrix estimation and hypothesis testing in complex t-distributed data (United States)

    Fortunati, Stefano; Gini, Fulvio; Greco, Maria S.


    Scatter matrix estimation and hypothesis testing are fundamental inference problems in a wide variety of signal processing applications. In this paper, we investigate and compare the matched, mismatched, and robust approaches to solve these problems in the context of the complex elliptically symmetric (CES) distributions. The matched approach is when the estimation and detection algorithms are tailored on the correct data distribution, whereas the mismatched approach refers to the case when the scatter matrix estimator and the decision rule are derived under a model assumption that is not correct. The robust approach aims at providing good estimation and detection performance, even if suboptimal, over a large set of possible data models, irrespective of the actual data distribution. Specifically, due to its central importance in both the statistical and engineering applications, we assume for the input data a complex t-distribution. We analyze scatter matrix estimators derived under the three different approaches and compare their mean square error (MSE) with the constrained Cramér-Rao bound (CCRB) and the constrained misspecified Cramér-Rao bound (CMCRB). In addition, the detection performance and false alarm rate (FAR) of the various detection algorithms are compared with that of the clairvoyant optimum detector.

  4. Studies of edge diffraction and scattering: Applications to room acoustics and auralization (United States)

    Torres, Rendell Reyes

    This thesis examines ways of including edge diffraction and surface scattering to improve room acoustics auralization, i.e., the binaural replication of an acoustic environment. The approach combines numerical and psychoacoustical studies to discern what level of computational accuracy is necessary to obtain perceptually adequate replication. In Paper I, a psychoacoustical investigation is performed on the ear's sensitivity to frequency-dependent changes in Lambert-modeled surface scattering. Using auralizations of a simulated concert hall, one finds that the frequency-dependent changes can be clearly audible over a wide frequency region and that its particular quality depends on the input signal. Frequency-dependent scattering, therefore, should be modeled, although not all auralization programs currently do this. Paper II delves into accurate modeling of edge diffraction. Using a validated time-domain model, computations are extended to include reflection/diffraction combinations, which significantly improve agreement with scale-model measurements of a stage house. Additionally, listening tests show that coloration changes due to edge diffraction are audible even for the conservative test geometry, but that second- order diffraction to non-shadowed receivers can often be neglected. Finally, a practical implementation for binaural simulation is proposed, completing a first major step toward computing edge diffraction for more accurate auralization. In Paper III, scattering is measured from various reflector arrays to allow study of physical diffraction phenomena and to gain new perspectives on modeling. This investigation also reveals general trends that can be of practical use in room acoustics when the wavelength is comparable to or greater than the individual panels. Results demonstrate (1)how the scattering from the array spreads over a considerably greater spatial extent than the ``specular reflection zone'' would predict, (2)how multi-element arrays

  5. Barrier distributions and scattering

    Energy Technology Data Exchange (ETDEWEB)

    Timmers, H.; Leigh, J.R.; Dasgupta, M.; Hinde, D.J.; Mein, J.C.; Morton, C.R.; Newton, J.O. [Department of Nuclear Physics, Australian National University, Canberra, ACT 0200 (Austria); Rowley, N. [Centre de Recherches Nucleaires, 23 Rue du Loess, F-67037 Strasbourg CEDEX 2 (France); Stefanini, A.M.; Ackermann, D.; Corradi, L.; He, J.H. [INFN, Laboratori Nazionali di Legnaro, Legnaro (PD) (Italy); Beghini, S.; Montagnoli, G.; Scarlassara, F.; Segato, G.F. [Universita di Padova and INFN Sezione di Padova, Padova (Italy)


    The extraction of representations of the fusion barrier distribution from backward-angle, quasi-elastic, elastic and transfer excitation functions is discussed. Such excitation functions have been measured for {sup 16}O, {sup 32}S and {sup 40}Ca projectiles incident on a variety of targets. The results are compared with representations obtained from fusion excitation functions. Varying in their sensitivity, all representations show evidence of the barrier structure. Differences between the scattering and the fusion representations can be related to the effects of coupling to residual, weak reaction channels. (author)

  6. Wave propagation scattering theory

    CERN Document Server

    Birman, M Sh


    The papers in this collection were written primarily by members of the St. Petersburg seminar in mathematical physics. The seminar, now run by O. A. Ladyzhenskaya, was initiated in 1947 by V. I. Smirnov, to whose memory this volume is dedicated. The papers in the collection are devoted mainly to wave propagation processes, scattering theory, integrability of nonlinear equations, and related problems of spectral theory of differential and integral operators. The book is of interest to mathematicians working in mathematical physics and differential equations, as well as to physicists studying va

  7. Raman scattering in crystals

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, D.F.


    A tutorial presentation is given of Raman scattering in crystals. The physical concepts are emphasized rather than the detailed mathematical formalism. Starting with an introduction to the concepts of phonons and conservation laws, the effects of photon-phonon interactions are presented. This interaction concept is shown for a simple cubic crystal and is extended to a uniaxial crystal. The correlation table method is used for determining the number and symmetry of the Raman active modes. Finally, examples are given to illustrate the relative ease of using this group theoretical method and the predictions are compared with measured Raman spectra. 37 refs., 17 figs., 6 tabs.

  8. Early detection of precancer using Polarized Light Scattering Spectroscopy (United States)

    Gurjar, Rajan; Backman, Vadim; Itzkan, Irving; Dasari, Ramachandra; Perelman, Lev; Feld, Michael; Badizadegan, Kamran


    We have developed a light scattering technique to detect early pre-cancerous changes in the tissues which, line the epithelial surfaces of the body. The majority of cancers are epithelial in nature. We use light reflection spectroscopy to observe the earliest sign, the enlargement of the index of the cells which, line this layer. Our method is based on the feature that single scattering in the backward direction retains the polarization of the light incident on nucleus in the epithelial layer whereas multiple scattering destroys the polarization. Collecting the backscattering spectral intensities of both polarizations, and taking their difference, we extract the single scattering component. The signals are analyzed to extract the nuclear density, size and the relative refractive index. The experimental results will be presented to illustrate the physical basis of the technique, and its biological application.

  9. Ultrathin aluminum sample cans for single crystal inelastic neutron scattering. (United States)

    Stone, M B; Loguillo, M J; Abernathy, D L


    Single crystal inelastic neutron scattering measurements are often performed using a sample environment for controlling sample temperature. One difficulty associated with this is establishing appropriate thermal coupling from the sample to the temperature controlled portion of the sample environment. This is usually accomplished via a sample can which thermally couples the sample environment to the sample can and the sample can to the sample via an exchange gas. Unfortunately, this can will contribute additional background signal to one's measurement. We present here the design of an ultrathin aluminum sample can based upon established technology for producing aluminum beverage cans. This design minimizes parasitic sample can scattering. Neutron scattering measurements comparing a machined sample can to our beverage can design clearly indicate a large reduction in scattering intensity and texture when using the ultrathin sample can design. We also examine the possibility of using standard commercial beverage cans as sample cans.

  10. Mechanical Design of the NSTX High-k Scattering Diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Feder, R.; Mazzucato, E.; Munsat, T.; Park, H,; Smith, D. R.; Ellis, R.; Labik, G.; Priniski, C.


    The NSTX High-k Scattering Diagnostic measures small-scale density fluctuations by the heterodyne detection of waves scattered from a millimeter wave probe beam at 280 GHz and {lambda}=1.07 mm. To enable this measurement, major alterations were made to the NSTX vacuum vessel and Neutral Beam armor. Close collaboration between the PPPL physics and engineering staff resulted in a flexible system with steerable launch and detection optics that can position the scattering volume either near the magnetic axis ({rho} {approx} .1) or near the edge ({rho} {approx} .8). 150 feet of carefully aligned corrugated waveguide was installed for injection of the probe beam and collection of the scattered signal in to the detection electronics.

  11. Wave scattering from statistically rough surfaces

    CERN Document Server

    Bass, F G; ter Haar, D


    Wave Scattering from Statistically Rough Surfaces discusses the complications in radio physics and hydro-acoustics in relation to wave transmission under settings seen in nature. Some of the topics that are covered include radar and sonar, the effect of variations in topographic relief or ocean waves on the transmission of radio and sound waves, the reproduction of radio waves from the lower layers of the ionosphere, and the oscillations of signals within the earth-ionosphere waveguide. The book begins with some fundamental idea of wave transmission theory and the theory of random processes a

  12. Time-domain electromagnetic scattering by a sphere in uniform translational motion. (United States)

    Garner, Timothy J; Lakhtakia, Akhlesh; Breakall, James K; Bohren, Craig F


    Scattering by a uniformly translating sphere of a pulse that modulates the amplitude of a linearly polarized plane wave was formulated using the frame-hopping method involving a laboratory inertial reference frame and the sphere's comoving inertial reference frame. The incident signal was defined in the laboratory frame and transformed to the comoving frame with the Lorentz transformation, thereby altering the incident signal's spectrum, direction of propagation of the carrier plane wave, and the direction of the incident electric field, depending on the sphere's velocity. In the comoving frame, the incident signal was Fourier-transformed to the frequency domain, and the scattered field phasors were computed in all directions using the constitutive parameters of the material of the sphere at rest. The scattered signal in the comoving frame was obtained using the inverse Fourier transform. Finally, the scattered signal in the laboratory frame was obtained by inverting the original Lorentz transformation. The backscattered signal was found to depend strongly on the sphere's velocity, when the sphere's speed is an appreciable fraction of the speed of light in free space. The change in the backscattered signal compared with the backscattered signal from a stationary sphere is the greatest when the sphere's velocity is either parallel or antiparallel to the direction of propagation of the incident signal. The backscattered signal is also affected by motion transverse to the incident signal's direction of propagation; then, the backscattered signal depends on whether or not the motion is aligned with the direction of the incident electric field.

  13. Signal Words (United States)

    SIGNAL WORDS TOPIC FACT SHEET NPIC fact sheets are designed to answer questions that are commonly asked by the ... making decisions about pesticide use. What are Signal Words? Signal words are found on pesticide product labels, ...

  14. Scatter factor and the c-met receptor: a paradigm for mesenchymal/epithelial interaction



    Epithelia and mesenchyme interact during various physiologic and pathologic processes. Scatter factor is a mesenchyme-derived cytokine that stimulates motility, proliferation, and morphogenesis of epithelia. Recent studies suggest that scatter factor and its receptor (c-met) mediate mesenchyme/epithelia signalling and even interconversion. In this mini-review, we will discuss how scatter factor and c-met may mediate interactions between mesenchyme and epithelia during embryogenesis, organ rep...

  15. Extracting chemical information from spectral data with multiplicative light scattering effects by optical path-length estimation and correction. (United States)

    Chen, Zeng-Ping; Morris, Julian; Martin, Elaine


    When analyzing complex mixtures that exhibit sample-to-sample variability using spectroscopic instrumentation, the variation in the optical path length, resulting from the physical variations inherent within the individual samples, will result in significant multiplicative light scattering perturbations. Although a number of algorithms have been proposed to address the effect of multiplicative light scattering, each has associated with it a number of underlying assumptions, which necessitates additional information relating to the spectra being attained. This information is difficult to obtain in practice and frequently is not available. Thus, with a view to removing the need for the attainment of additional information, a new algorithm, optical path-length estimation and correction (OPLEC), is proposed. The methodology is applied to two near-infrared transmittance spectral data sets (powder mixture data and wheat kernel data), and the results are compared with the extended multiplicative signal correction (EMSC) and extended inverted signal correction (EISC) algorithms. Within the study, it is concluded that the EMSC algorithm cannot be applied to the wheat kernel data set due to core information for the implementation of the algorithm not being available, while the analysis of the powder mixture data using EISC resulted in incorrect conclusions being drawn and hence a calibration model whose performance was unacceptable. In contrast, OPLEC was observed to effectively mitigate the detrimental effects of physical light scattering and significantly improve the prediction accuracy of the calibration models for the two spectral data sets investigated without any additional information pertaining to the calibration samples being required.

  16. Feasibility of field-based light scattering spectroscopy (United States)

    Yang, Changhuei; Perelman, Lev T.; Wax, Adam; Dasari, Ramachandra R.; Feld, Michael S.


    Light scattering spectroscopy (LSS) is a new technique capable of accurately measuring the features of nuclei and other cellular organelles in situ. We present the considerations required to implement and interpret field- based detection in LSS, where the scattered electric field is detected interferometrically, and demonstrate that the technique is experimentally feasible. A theoretical formalism for modeling field-based LSS signals based on Mie scattering is presented. Phase-front uniformity is shown to play an important and novel role. Results of heterodyne experiments with polystyrene microspheres that localize LSS signals to a region about 30 micrometers in axial extent are reported. In addition, differences between field-based LSS and the earlier intensity-based LSS are discussed.

  17. An improved laser-Rayleigh scattering photodetection system (United States)

    Dowling, D. R.; Lang, D. B.; Dimotakis, P. E.


    An improved photodetection system for high-resolution laser Rayleigh scattering measurements has been developed that utilizes a solid-state detector coupled to a custom-designed low-noise transimpedance amplifier. The resulting system, based on a PIN photodiode, is less expensive, inherently safer, less delicate, and, depending on the detected light level, may exhibit higher signal-to-noise ratios than photodetection systems based on photomultiplier tubes. The frequency response of the system was designed to be uniform (3 percent peak variation) from dc to nearly 100 kHz. Concentration fluctuation spectra of a high-scattering cross-section label gas discharging into a density-matched low-scattering-cross-section quiescent reservoir gas were measured using this system. Spectral signal-to-noise ratios as high as 7 decades were achieved under some conditions in parts of the spectrum.

  18. Photon-Photon Scattering at the Photon Linear Collider


    Jikia, G.; Tkabladze, A.


    Photon-photon scattering at the Photon Linear Collider is considered. Explicit formulas for helicity amplitudes due to $W$ boson loops are presented. It is shown that photon-photon scattering should be easily observable at PLC and separation of the $W$ loop contribution (which dominates at high energies) will be possible at $e^+e^-$ c.m. energy of 500~GeV or higher.

  19. Magnetic dipole transitions and spin currents in inelastic electron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Lipas, P.O.; Koskinen, M. (Jyvaeskylae Univ. (Finland). Dept. of Physics); Harter, H.; Nojarov, R.; Faessler, A. (Tuebingen Univ. (Germany, F.R.). Inst. fuer Theoretische Physik)


    We use the microscopic interacting-boson approximation (IBA-2) to calculate the nuclear M1 transition current density for excitation by inelastic electron scattering. Although the strong 1{sup +} excitations are commonly regarded as due to proton convection, we find, with {sup 164}Dy as a test case, that proton and neutron spins cause strong oscillations in the current and are responsible for high-q-scattering. (orig.).

  20. Prospects for electron scattering on unstable, exotic nuclei (United States)

    Suda, Toshimi; Simon, Haik


    Electron scattering off radioactive ions becomes feasible for the first time due to advances in storage ring and trapping techniques in conjunction with intense secondary beams from novel beam facilities. Using a point-like purely leptonic probe enables the investigation of charge distributions and electromagnetic excitations in β-unstable exotic nuclei with an enhanced overshoot in proton and neutron numbers and the use of QED, one of the most precisely studied theories, for describing the scattering process.

  1. Geometrical calibration of the NBS electron scattering apparatus. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Penner, S.; Fivozinsky, S.P.; Lightbody, J.W. Jr.; Cardman, L.S.; Trower, W.P.


    A comprehensive calibration of the geometry of the NBS electron scattering apparatus is described. A complete set of measured parameters is tabulated in this report. Combining these parameters with observed values of certain variables as described herein permits the accurate determination of the solid angle, scattering angle, and target angle for each cross section measurement made with the apparatus. The uncertainty in cross section measurement due to the imprecision of the geometry calibrations is less than one part in 1,000. (GRA)

  2. Nanostructured surface enhanced Raman scattering substrates for explosives detection

    DEFF Research Database (Denmark)

    Schmidt, Michael Stenbaek; Olsen, Jesper Kenneth; Boisen, Anja


    Here we present a method for trace detection of explosives in the gas phase using novel surface enhanced Raman scattering (SERS) spectroscopy substrates. Novel substrates that produce an exceptionally large enhancement of the Raman effect were used to amplify the Raman signal of explosives molecu...

  3. Benchmarking the inelastic neutron scattering soil carbon method (United States)

    The herein described inelastic neutron scattering (INS) method of measuring soil carbon was based on a new procedure for extracting the net carbon signal (NCS) from the measured gamma spectra and determination of the average carbon weight percent (AvgCw%) in the upper soil layer (~8 cm). The NCS ext...

  4. Efficient feature for classification of eye movements using electrooculography signals

    Directory of Open Access Journals (Sweden)

    Phukpattaranont Pornchai


    Full Text Available Electrooculography (EOG signal is widely and successfully used to detect activities of human eye. The advantages of the EOG-based interface over other conventional interfaces have been presented in the last two decades; however, due to a lot of information in EOG signals, the extraction of useful features should be done before the classification task. In this study, an efficient feature extracted from two directional EOG signals: vertical and horizontal signals has been presented and evaluated. There are the maximum peak and valley amplitude values, the maximum peak and valley position values, and slope, which are derived from both vertical and horizontal signals. In the experiments, EOG signals obtained from five healthy subjects with ten directional eye movements were employed: up, down, right, left, up-right, up-left, down-right down-left clockwise and counterclockwise. The mean feature values and their standard deviations have been reported. The difference between the mean values of the proposed feature from different eye movements can be clearly seen. Using the scatter plot, the differences in features can be also clearly observed. Results show that classification accuracy can approach 100% with a simple distinction feature rule. The proposed features can be useful for various advanced human-computer interface applications in future researches.

  5. Electromagnetic Scattering and Material Characterization

    CERN Document Server

    Omar, Abbas


    Based on the author's more-than 30 years of experience, this first-of-its-kind volume presents a comprehensive and systematic analysis of electromagnetic fields and their scattering by material objects. The book considers all three categories of scattering environments commonly used for material measurements – unbounded regions, waveguides, and cavity resonators. The book covers such essential topics as electromagnetic field propagation, radiation, and scattering, containing mathematically rigorous approaches for the computation of electromagnetic fields and the explanation of their behavior.

  6. Wavelength-independent constant period spin-echo modulated small angle neutron scattering

    NARCIS (Netherlands)

    Sales, Morten; Plomp, J.; Habicht, Klaus; Tremsin, Anton; Bouwman, W.G.; Strobl, Markus


    Spin-Echo Modulated Small Angle Neutron Scattering (SEMSANS) in Time-of-Flight (ToF) mode has been shown to be a promising technique for measuring (very) small angle neutron scattering (SANS) signals and performing quantitative Dark-Field Imaging (DFI), i.e., SANS with 2D spatial resolution.

  7. Discrimination of human cytotoxic lymphocytes from regulatory and B-lymphocytes by orthogonal light scattering

    NARCIS (Netherlands)

    Terstappen, Leonardus Wendelinus Mathias Marie; de Grooth, B.G.; ten Napel, C.H.H.; van Berkel, W.; Greve, Jan


    Light scattering properties of human lymphocyte subpopulations selected by immunofluorescence were studied with a flow cytometer. Regulatory and B-lymphocytes showed a low orthogonal light scatter signal, whereas cytotoxic lymphocytes identified with leu-7, leu-11 and leu-15 revealed a large

  8. Coherent detection of spontaneous Brillouin scattering for distributed temperature sensing using a Brillouin laser (United States)

    Lecoeuche, V.; Webb, David J.; Pannell, Christopher N.; Jackson, David A.


    Distributed temperature sensors based on Brillouin scattering are attractive because they offer very large sensing length. The intensity of spontaneous Brillouin scattering is directly proportional to the temperature of the fiber, and permits a measurement independent of the strain applied to it. We report on a novel system to detect this signal, incorporating a mode-locked Brillouin fiber ring laser.

  9. Modification of the collective Thomson scattering radiometer in the search for parametric decay on TEXTOR

    DEFF Research Database (Denmark)

    Nielsen, Stefan Kragh; Salewski, Mirko; Bongers, W.


    Strong scattering of high-power millimeter waves at 140 GHz has been shown to take place in heating and current-drive experiments at TEXTOR when a tearing mode is present in the plasma. The scattering signal is at present supposed to be generated by the parametric decay instability. Here we descr...... with independent backscattering radiometer data....

  10. Virtual-pion and two-photon production in pp scattering

    NARCIS (Netherlands)

    Scholten, O; Korchin, AY

    Two-photon production in pp scattering is proposed as a means of studying virtual-pion emission. Such a process is complementary to real-pion emission in pp scattering. The virtual-pion signal is embedded in a background of double-photon bremsstrahlung. We have developed a model to describe this

  11. Advances in total scattering analysis

    Energy Technology Data Exchange (ETDEWEB)

    Proffen, Thomas E [Los Alamos National Laboratory; Kim, Hyunjeong [Los Alamos National Laboratory


    In recent years the analysis of the total scattering pattern has become an invaluable tool to study disordered crystalline and nanocrystalline materials. Traditional crystallographic structure determination is based on Bragg intensities and yields the long range average atomic structure. By including diffuse scattering into the analysis, the local and medium range atomic structure can be unravelled. Here we give an overview of recent experimental advances, using X-rays as well as neutron scattering as well as current trends in modelling of total scattering data.

  12. Light scattering by small particles

    CERN Document Server

    Hulst, H C van de


    ""A must for researchers using the techniques of light scattering."" ? S. C. Snowdon, Journal of the Franklin InstituteThe measurement of light scattering of independent, homogeneous particles has many useful applications in physical chemistry, meteorology and astronomy. There is, however, a sizeable gap between the abstract formulae related to electromagnetic-wave-scattering phenomena, and the computation of reliable figures and curves. Dr. van de Hulst's book enables researchers to bridge that gap. The product of twelve years of work, it is an exhaustive study of light-scattering properties

  13. Dispersion Decay and Scattering Theory

    CERN Document Server

    Komech, Alexander


    A simplified, yet rigorous treatment of scattering theory methods and their applications Dispersion Decay and Scattering Theory provides thorough, easy-to-understand guidance on the application of scattering theory methods to modern problems in mathematics, quantum physics, and mathematical physics. Introducing spectral methods with applications to dispersion time-decay and scattering theory, this book presents, for the first time, the Agmon-Jensen-Kato spectral theory for the Schr?dinger equation, extending the theory to the Klein-Gordon equation. The dispersion decay plays a crucial role i

  14. Review of interferometric spectroscopy of scattered light for the quantification of subdiffractional structure of biomaterials (United States)

    Cherkezyan, Lusik; Zhang, Di; Subramanian, Hariharan; Capoglu, Ilker; Taflove, Allen; Backman, Vadim


    Optical microscopy is the staple technique in the examination of microscale material structure in basic science and applied research. Of particular importance to biology and medical research is the visualization and analysis of the weakly scattering biological cells and tissues. However, the resolution of optical microscopy is limited to ≥200 nm due to the fundamental diffraction limit of light. We review one distinct form of the spectroscopic microscopy (SM) method, which is founded in the analysis of the second-order spectral statistic of a wavelength-dependent bright-field far-zone reflected-light microscope image. This technique offers clear advantages for biomedical research by alleviating two notorious challenges of the optical evaluation of biomaterials: the diffraction limit of light and the lack of sensitivity to biological, optically transparent structures. Addressing the first issue, it has been shown that the spectroscopic content of a bright-field microscope image quantifies structural composition of samples at arbitrarily small length scales, limited by the signal-to-noise ratio of the detector, without necessarily resolving them. Addressing the second issue, SM utilizes a reference arm, sample arm interference scheme, which allows us to elevate the weak scattering signal from biomaterials above the instrument noise floor.

  15. Behavior of aqueous Tetrabutylammonium bromide - a combined approach of microscopic simulation and neutron scattering

    CERN Document Server

    Bhowmik, Debsindhu


    Aqueous solution of tetrabutylammonium bromide is studied by quasi-elastic neutron scattering, to give information on the dynamic modes involving the ions present. Using a careful combination of two techniques, time-of-flight (TOF) and neutron spin echo (NSE), we de- couple the dynamic information in both the coherently and incoherently scattered signal from this system. We take advantage of the different intensity ratio of the two signals, as detected by each of the techniques, to achieve this decoupling. By using heavy water as the sol- vent, the tetrabutylammonium cation is the only hydrogen-containing species in the system and gives rise to a significant incoherent scattered intensity. The dynamic analysis of the incoherent signal (measured by TOF) leads to a translational diffusion coefficient of the cation as that is in good agreement with previous NMR, neutron scattering and tracer diffusion measurements. The dynamic analysis of the coherent signal observed at wave-vectors < 0.6 angstrom^(-1) (measu...

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

    NARCIS (Netherlands)

    Macquart, JP

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

  17. The Probing Radio Signal Polarization Effect on Separation Efficiency of Surface Target Response

    Directory of Open Access Journals (Sweden)

    A. N. Pinchuk


    Full Text Available The aim of the study was a quantitative analysis of the level of interference with radar monitoring characteristics of surface targets, caused by the scattered electromagnetic field, arising due to the interaction between radio waves and sea surface, which is a study aspect a radiooceanography encompasses. Backscatter signal, arising from the interaction of radio waves and sea surface, extends in a direction opposite the probing radar signal of spread marine and coastal radar stations.With radar sounding of sea surface at high incidence angles of radio waves, a basic physical mechanism to form the received signal is resonant (Bragg scattering, and at small incidence angles of radio waves it is quasi-specular reflection. Consequently, the energy of electromagnetic radiation, backscattered by the sea surface, depends on the type of wave polarization: for horizontal polarization it is less than for vertical one.The paper presents a mathematical model, which describes dependence of interference level caused by interaction between radio waves and sea surface, on the radio wave polarization for the case when the same polarization is used to sent-out and receive a radio wave.To determine the noise reduction to be achievable with radar monitoring the surface targets by selecting the polarization of the probing radar signal, a signal/noise ratio is analyzed for its different polarizations.It is shown that in order to reduce the noise level caused by the interaction between radio waves and sea surface, it is possible to use the differences in the level of scattered radio signals of different polarization: with horizontally-polarized radar operation at incidence angles of 75°- 85° a signal/noise ratio is by 20-35 dB higher than that of vertically- polarized one.

  18. Surface enhanced Raman scattering

    CERN Document Server

    Furtak, Thomas


    In the course of the development of surface science, advances have been identified with the introduction of new diagnostic probes for analytical characterization of the adsorbates and microscopic structure of surfaces and interfaces. Among the most recently de­ veloped techniques, and one around which a storm of controversy has developed, is what has now been earmarked as surface enhanced Raman scattering (SERS). Within this phenomenon, molecules adsorbed onto metal surfaces under certain conditions exhibit an anomalously large interaction cross section for the Raman effect. This makes it possible to observe the detailed vibrational signature of the adsorbate in the ambient phase with an energy resolution much higher than that which is presently available in electron energy loss spectroscopy and when the surface is in contact with a much larger amount of material than that which can be tolerated in infrared absorption experiments. The ability to perform vibrational spectroscopy under these conditions would l...

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

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


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

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

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

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


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

  2. Directional Dipole Model for Subsurface Scattering

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall; Hachisuka, Toshiya; Kjeldsen, Thomas Kim


    Rendering translucent materials using Monte Carlo ray tracing is computationally expensive due to a large number of subsurface scattering events. Faster approaches are based on analytical models derived from diffusion theory. While such analytical models are efficient, they miss out on some...... translucency effects in the rendered result. We present an improved analytical model for subsurface scattering that captures translucency effects present in the reference solutions but remaining absent with existing models. The key difference is that our model is based on ray source diffusion, rather than...... point source diffusion. A ray source corresponds better to the light that refracts through the surface of a translucent material. Using this ray source, we are able to take the direction of the incident light ray and the direction toward the point of emergence into account. We use a dipole construction...

  3. Wave scattering in spatially inhomogeneous currents (United States)

    Churilov, Semyon; Ermakov, Andrei; Stepanyants, Yury


    We analytically study a scattering of long linear surface waves on stationary currents in a duct (canal) of constant depth and variable width. It is assumed that the background velocity linearly increases or decreases with the longitudinal coordinate due to the gradual variation of duct width. Such a model admits an analytical solution of the problem in hand, and we calculate the scattering coefficients as functions of incident wave frequency for all possible cases of sub-, super-, and transcritical currents. For completeness we study both cocurrent and countercurrent wave propagation in accelerating and decelerating currents. The results obtained are analyzed in application to recent analog gravity experiments and shed light on the problem of hydrodynamic modeling of Hawking radiation.

  4. Holographic Imaging and Iterative Phase Optimization Methods for Focusing and Transmitting Light in Scattering Media (United States)

    Purcell, Michael James

    Existing methods for focusing and imaging through strongly scattering materials are often limited by speed, the need for invasive feedback, and the shallow depth of penetration of photons into the material. These limitations have motivated the present research into the development of a new iterative phase optimization method for improving transmission of light through a sample of strongly scattering material. A new method, based on the detection of back-scattered light combined with active (phase-only) wavefront control was found to be partially successful, decreasing the power of backscattered incident light at 488 nm wavelength by approximately 35% in a 626 mum thick sample of Yttria (Y2O3) nanopowder (mean particle size 26 nm) in clear epoxy with transport mean free path length ˜116 mum. However, the observed transmitted power did not show simultaneous improvement. The conclusion was reached that scattering to the sides of the sample and polarization scrambling were responsible for the lack of improved transmission with this method. Some ideas for improvement are discussed in the thesis. This research subsequently led to the development of a lensless holographic imaging method based on a rotating diffuser for statistical averaging of the optical signal for overcoming speckle caused by reflection from a rough surface. This method made it possible to reduce background variations of intensity due to speckle and improve images reflected from rough, immobile surfaces with no direct path for photons between the object and camera. Improvements in the images obtained with this technique were evaluated quantitatively by comparing SSIM indices and were found to offer practical advances for transmissive and reflective geometries alike.

  5. The measurement of self-diffusion coefficients in liquid metals with quasielastic neutron scattering


    Meyer, A.


    Quasielastic incoherent neutron scattering (QENS) has proven to be a versatile tool to study self diffusion of atoms in liquid metals. Here it is shown, that coherent contributions to the signal in the small q limit appear as a flat and energy independent constant to the QENS signal in single-component liquid metals even for systems with a small incoherent scattering cross section, like aluminum. Container-less processing via electromagnetic or electrostatic levitation devices, especially des...

  6. Using phase for radar scatterer classification (United States)

    Moore, Linda J.; Rigling, Brian D.; Penno, Robert P.; Zelnio, Edmund G.


    Traditional synthetic aperture radar (SAR) systems tend to discard phase information of formed complex radar imagery prior to automatic target recognition (ATR). This practice has historically been driven by available hardware storage, processing capabilities, and data link capacity. Recent advances in high performance computing (HPC) have enabled extremely dense storage and processing solutions. Therefore, previous motives for discarding radar phase information in ATR applications have been mitigated. First, we characterize the value of phase in one-dimensional (1-D) radar range profiles with respect to the ability to correctly estimate target features, which are currently employed in ATR algorithms for target discrimination. These features correspond to physical characteristics of targets through radio frequency (RF) scattering phenomenology. Physics-based electromagnetic scattering models developed from the geometrical theory of diffraction are utilized for the information analysis presented here. Information is quantified by the error of target parameter estimates from noisy radar signals when phase is either retained or discarded. Operating conditions (OCs) of signal-tonoise ratio (SNR) and bandwidth are considered. Second, we investigate the value of phase in 1-D radar returns with respect to the ability to correctly classify canonical targets. Classification performance is evaluated via logistic regression for three targets (sphere, plate, tophat). Phase information is demonstrated to improve radar target classification rates, particularly at low SNRs and low bandwidths.

  7. 154 GHz collective Thomson scattering in LHD (United States)

    Tanaka, K.; Nishiura, M.; Kubo, S.; Shimozuma, T.; Saito, T.; Moseev, D.; Abramovic, I.


    Collective Thomson scattering (CTS) was developed by using a 154 GHz gyrotron, and the first data has been obtained. Already, 77 GHz CTS has worked successfully. However, in order to access higher density region, 154 GHz option enhances the usability that reduces the refraction effect, which deteriorates in the local measurements. The system in the down converted frequency was almost identical to the system for 77 GHz. Probing beam, a notch filter, a mixer, and a local oscillator in the receiver system for 77 GHz option were replaced to those for the 154 GHz option. 154 GHz gyrotron was originally prepared for the second harmonic electron cyclotron heating (ECRH) at 2.75 T. However, scattering signal was masked by the second harmonic electron cyclotron emission (ECE) at 2.75 T. Therefore, 154 GHz CTS was operated at 1.375 T with fourth harmonic ECE, and an acceptable signal to noise ratio was obtained. There is a signature of fast ion components with neutral beam (NB) injection. In addition, the CTS spectrum became broader in hydrogen discharge than in deuterium discharge, as the theoretical CTS spectrum expects. This observation indicates a possibility to identify ion species ratio by the 154 GHz CTS diagnostic.

  8. Exclusive scattering off the deuteron

    Energy Technology Data Exchange (ETDEWEB)

    Amrath, D.


    Exclusive processes are a special class of processes giving insight into the inner structure of hadrons. In this thesis we consider two exclusive processes and compute their total cross sections as well as the beam charge and beam polarization asymmetries for different kinematical constraints. These calculations o er the opportunity to get access to the nonperturbative GPDs. Theoretically they can be described with the help of models. The rst process we investigate contains a GPD of the pion, which is basically unknown so far. We include different models and make predictions for observables that could in principle be measured at HERMES at DESY and CLAS at JLab. The second process we consider is electron-deuteron scattering in the kinematical range where the deuteron breaks up into a proton and a neutron. This can be used to investigate the neutron, which cannot be taken as a target due to its lifetime of approximately 15 minutes. For the calculation of the electron-deuteron cross section we implement models for the proton and neutron GPDs. Once there are experimental data available our calculations are ready for comparison. (orig.)

  9. Dynamic measurement of forward scattering

    DEFF Research Database (Denmark)

    Appel-Hansen, Jørgen; Rusch, W.


    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...

  10. Quantum scattering at low energies

    DEFF Research Database (Denmark)

    Derezinski, Jan; Skibsted, Erik


    For a class of negative slowly decaying potentials, including V(x):=−γ|x|−μ with 0quantum mechanical scattering theory in the low-energy regime. Using appropriate modifiers of the Isozaki–Kitada type we show that scattering theory is well behaved on the whole continuous spectrum...

  11. Quantum scattering at low energies

    DEFF Research Database (Denmark)

    Derezinski, Jan; Skibsted, Erik

    For a class of negative slowly decaying potentials, including with , we study the quantum mechanical scattering theory in the low-energy regime. Using modifiers of the Isozaki--Kitada type we show that scattering theory is well behaved on the {\\it whole} continuous spectrum of the Hamiltonian...

  12. Light scattering in ophthalmic research (United States)

    Tuchin, Valery V.


    In the overview optical models of cornea, sclera, and crystalline lens humor will be presented. On the basis of these models eye tissue transmittance spectra and scattering indicatrices for the main informative elements of the mueller matrix will be analyzed. This paper will discuss some problems of eye tissue optical characteristics control, and possibilities and perspectives of elastic scattering spectroscopy in cataract diagnostics.

  13. Quantum scattering in one dimension

    Energy Technology Data Exchange (ETDEWEB)

    Barlette, Vania E. [Centro Universitario Franciscano, Santa Maria, RS (Brazil); Leite, Marcelo M. [Departamento de Fisica, Instituto Tecnologico de Aeronautica, Centro Tecnico Aeroespacial, Sao Jose dos Campos, SP (Brazil); Adhikari, Sadhan K. [Instituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, SP (Brazil)


    A self-contained discussion of non-relativistic quantum scattering is presented in the case of central potentials in one space dimension, which will facilitate the understanding of the more complex scattering theory in two and three dimensions. The present discussion illustrates in a simple way the concepts of partial-wave decomposition, phase shift, optical theorem and effective-range expansion. (author)

  14. Electron scattering for exotic nuclei

    Indian Academy of Sciences (India)


    Nov 4, 2014 ... determine the charge density distributions of short-lived exotic nuclei by elastic electron scattering. The first collision ... Electron scattering of highly unstable nuclei is not easy because it is difficult to produce ... both ends form a mirror potential to keep the ions longitudinally inside the SCRIT device, and the ...

  15. Surface scattering from ceramic phosphors (United States)

    Lenef, Alan; Kelso, John; Peters, Christopher


    Scattering from phosphor converters and epitaxial surfaces is critical for solid state lighting device performance. Volume and surface scattering in solid state lighting devices can play a critical role in efficiency/efficacy, color points, and color angular consistency. Surface scattering in particular has not been well characterized in solid state lighting devices and can be complex to model. Because large angle scattering is important in lighting applications, surface scattering models generally require vector electromagnetic theory to avoid ambiguities often associated with scalar theory at these angles. Furthermore, surface features are often on the order of a few wavelengths, bringing ray tracing approaches into question. In this work, experimental angular scattering measurements are made on ceramic phosphor components where surface scattering dominates. The surface ceramic grain structure is responsible for the scattering. The results are compared to approximate statistical vector theory predictions that use the height autocorrelation functions as input. The autocorrelation measurements were derived from atomic-force microscopy topography measurements. Resulting predictions are in fairly good agreement with measurements.

  16. Ligand-induced dynamical change of G-protein-coupled receptor revealed by neutron scattering (United States)

    Shrestha, Utsab R.; Bhowmik, Debsindhu; Mamontov, Eugene; Chu, Xiang-Qiang

    Light activation of the visual G-protein-coupled receptor rhodopsin leads to the significant change in protein conformation and structural fluctuations, which further activates the cognate G-protein (transducin) and initiates the biological signaling. In this work, we studied the rhodopsin activation dynamics using state-of-the-art neutron scattering technique. Our quasi-elastic neutron scattering (QENS) results revealed a broadly distributed relaxation rate of the hydrogen atom in rhodopsin on the picosecond to nanosecond timescale (beta-relaxation region), which is crucial for the protein function. Furthermore, the application of mode-coupling theory to the QENS analysis uncovers the subtle changes in rhodopsin dynamics due to the retinal cofactor. Comparing the dynamics of the ligand-free apoprotein, opsin versus the dark-state rhodopsin, removal of the retinal cofactor increases the relaxation time in the beta-relaxation region, which is due to the possible open conformation. Moreover, we utilized the concept of free-energy landscape to explain our results for the dark-state rhodopsin and opsin dynamics, which can be further applied to other GPCR systems to interpret various dynamic behaviors in ligand-bound and ligand-free protein.

  17. Real-time imaging through strongly scattering media: seeing through turbid media, instantly (United States)

    Sudarsanam, Sriram; Mathew, James; Panigrahi, Swapnesh; Fade, Julien; Alouini, Mehdi; Ramachandran, Hema


    Numerous everyday situations like navigation, medical imaging and rescue operations require viewing through optically inhomogeneous media. This is a challenging task as photons propagate predominantly diffusively (rather than ballistically) due to random multiple scattering off the inhomogenieties. Real-time imaging with ballistic light under continuous-wave illumination is even more challenging due to the extremely weak signal, necessitating voluminous data-processing. Here we report imaging through strongly scattering media in real-time and at rates several times the critical flicker frequency of the eye, so that motion is perceived as continuous. Two factors contributed to the speedup of more than three orders of magnitude over conventional techniques - the use of a simplified algorithm enabling processing of data on the fly, and the utilisation of task and data parallelization capabilities of typical desktop computers. The extreme simplicity of the technique, and its implementation with present day low-cost technology promises its utility in a variety of devices in maritime, aerospace, rail and road transport, in medical imaging and defence. It is of equal interest to the common man and adventure sportsperson like hikers, divers, mountaineers, who frequently encounter situations requiring realtime imaging through obscuring media. As a specific example, navigation under poor visibility is examined.

  18. Label-Free Biomedical Imaging Using High-Speed Lock-In Pixel Sensor for Stimulated Raman Scattering. (United States)

    Mars, Kamel; Lioe, De Xing; Kawahito, Shoji; Yasutomi, Keita; Kagawa, Keiichiro; Yamada, Takahiro; Hashimoto, Mamoru


    Raman imaging eliminates the need for staining procedures, providing label-free imaging to study biological samples. Recent developments in stimulated Raman scattering (SRS) have achieved fast acquisition speed and hyperspectral imaging. However, there has been a problem of lack of detectors suitable for MHz modulation rate parallel detection, detecting multiple small SRS signals while eliminating extremely strong offset due to direct laser light. In this paper, we present a complementary metal-oxide semiconductor (CMOS) image sensor using high-speed lock-in pixels for stimulated Raman scattering that is capable of obtaining the difference of Stokes-on and Stokes-off signal at modulation frequency of 20 MHz in the pixel before reading out. The generated small SRS signal is extracted and amplified in a pixel using a high-speed and large area lateral electric field charge modulator (LEFM) employing two-step ion implantation and an in-pixel pair of low-pass filter, a sample and hold circuit and a switched capacitor integrator using a fully differential amplifier. A prototype chip is fabricated using 0.11 μm CMOS image sensor technology process. SRS spectra and images of stearic acid and 3T3-L1 samples are successfully obtained. The outcomes suggest that hyperspectral and multi-focus SRS imaging at video rate is viable after slight modifications to the pixel architecture and the acquisition system.

  19. Label-Free Biomedical Imaging Using High-Speed Lock-In Pixel Sensor for Stimulated Raman Scattering

    Directory of Open Access Journals (Sweden)

    Kamel Mars


    Full Text Available Raman imaging eliminates the need for staining procedures, providing label-free imaging to study biological samples. Recent developments in stimulated Raman scattering (SRS have achieved fast acquisition speed and hyperspectral imaging. However, there has been a problem of lack of detectors suitable for MHz modulation rate parallel detection, detecting multiple small SRS signals while eliminating extremely strong offset due to direct laser light. In this paper, we present a complementary metal-oxide semiconductor (CMOS image sensor using high-speed lock-in pixels for stimulated Raman scattering that is capable of obtaining the difference of Stokes-on and Stokes-off signal at modulation frequency of 20 MHz in the pixel before reading out. The generated small SRS signal is extracted and amplified in a pixel using a high-speed and large area lateral electric field charge modulator (LEFM employing two-step ion implantation and an in-pixel pair of low-pass filter, a sample and hold circuit and a switched capacitor integrator using a fully differential amplifier. A prototype chip is fabricated using 0.11 μm CMOS image sensor technology process. SRS spectra and images of stearic acid and 3T3-L1 samples are successfully obtained. The outcomes suggest that hyperspectral and multi-focus SRS imaging at video rate is viable after slight modifications to the pixel architecture and the acquisition system.

  20. Polarized scattered light from self-luminous exoplanets. Three-dimensional scattering radiative transfer with ARTES (United States)

    Stolker, T.; Min, M.; Stam, D. M.; Mollière, P.; Dominik, C.; Waters, L. B. F. M.


    Context. Direct imaging has paved the way for atmospheric characterization of young and self-luminous gas giants. Scattering in a horizontally-inhomogeneous atmosphere causes the disk-integrated polarization of the thermal radiation to be linearly polarized, possibly detectable with the newest generation of high-contrast imaging instruments. Aims: We aim to investigate the effect of latitudinal and longitudinal cloud variations, circumplanetary disks, atmospheric oblateness, and cloud particle properties on the integrated degree and direction of polarization in the near-infrared. We want to understand how 3D atmospheric asymmetries affect the polarization signal in order to assess the potential of infrared polarimetry for direct imaging observations of planetary-mass companions. Methods: We have developed a three-dimensional Monte Carlo radiative transfer code (ARTES) for scattered light simulations in (exo)planetary atmospheres. The code is applicable to calculations of reflected light and thermal radiation in a spherical grid with a parameterized distribution of gas, clouds, hazes, and circumplanetary material. A gray atmosphere approximation is used for the thermal structure. Results: The disk-integrated degree of polarization of a horizontally-inhomogeneous atmosphere is maximal when the planet is flattened, the optical thickness of the equatorial clouds is large compared to the polar clouds, and the clouds are located at high altitude. For a flattened planet, the integrated polarization can both increase or decrease with respect to a spherical planet which depends on the horizontal distribution and optical thickness of the clouds. The direction of polarization can be either parallel or perpendicular to the projected direction of the rotation axis when clouds are zonally distributed. Rayleigh scattering by submicron-sized cloud particles will maximize the polarimetric signal whereas the integrated degree of polarization is significantly reduced with micron

  1. Automated detection of satellite contamination in incoherent scatter radar spectra

    Directory of Open Access Journals (Sweden)

    J. Porteous


    Full Text Available Anomalous ion line spectra have been identified in many experiments. Such spectra are defined as deviations from the standard symmetric "double-humped" spectra derived from incoherent scatter radar echoes from the upper atmosphere. Some anomalous spectra – where there are sharp enhancements of power over restricted height ranges – have been attributed to satellite contamination in the beam path. Here we outline a method for detecting such contamination, and review in detail a few cases where the method enables the identification of anomalous spectra as satellite echoes, subsequently ascribed to specific orbital objects. The methods used here to identify such satellites provide a useful way of distinguishing anomalous spectra due to satellites from those of geophysical origin. Analysis of EISCAT Svalbard Radar data reveals that an average of 8 satellites per hour are found to cross the beam. Based on a relatively small sample of the data set, it appears that at least half of the occurrences of anomalous spectra are caused by satellite contamination rather than being of geophysical origin.Key words. Ionosphere (auroral ionosphere, instruments and techniques – Radio Science (signal processing

  2. Relation between ultrasonic scattering and microstructure of polycrystalline materials

    Energy Technology Data Exchange (ETDEWEB)

    Dupond, O; Feuilly, N; Chassignole, B [EDF R and D, Material and Mecanics of Components Department, Site des Renardieres, 77818 Moret-sur-Loing (France); Fouquet, T [EDF R and D, Neutronics simulation, information technologies and scientific calculations department, Clamart (France); Moysan, J; Corneloup, G [Laboratoire de Caracterisation Non-Destructive, Universite de la Mediterranee, 13625 Aix-en-Provence (France)


    Ultrasonic testing is a very common volumetric technique used in industry in order to detect and characterized defects. Within the framework of the maintenance of its nuclear power stations, Electricite de France (EDF) uses this technique on various components. In the case of polycrystalline materials, the scattering of the ultrasonic wave can result in an important attenuation of the signal and the appearance of structural noise. In the present study, we propose to analyze scattering noise in relation to the microstructure of the material. Both experimental and 2D finite elements modelling results are presented for different controlled structure of an homogeneous and isotropic Ni-based alloy.

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

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


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

  4. Doppler Spectrum from Moving Scatterers in a Random Environment

    DEFF Research Database (Denmark)

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


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

  5. Nonreciprocal wave scattering on nonlinear string-coupled oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Lepri, Stefano, E-mail: [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, via Madonna del Piano 10, I-50019 Sesto Fiorentino (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino (Italy); Pikovsky, Arkady [Department of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str 24/25, Potsdam (Germany); Department of Control Theory, Nizhni Novgorod State University, Gagarin Av. 23, 606950, Nizhni Novgorod (Russian Federation)


    We study scattering of a periodic wave in a string on two lumped oscillators attached to it. The equations can be represented as a driven (by the incident wave) dissipative (due to radiation losses) system of delay differential equations of neutral type. Nonlinearity of oscillators makes the scattering non-reciprocal: The same wave is transmitted differently in two directions. Periodic regimes of scattering are analyzed approximately, using amplitude equation approach. We show that this setup can act as a nonreciprocal modulator via Hopf bifurcations of the steady solutions. Numerical simulations of the full system reveal nontrivial regimes of quasiperiodic and chaotic scattering. Moreover, a regime of a “chaotic diode,” where transmission is periodic in one direction and chaotic in the opposite one, is reported.

  6. Scattering in the ultrastrong regime: nonlinear optics with one photon. (United States)

    Sanchez-Burillo, E; Zueco, D; Garcia-Ripoll, J J; Martin-Moreno, L


    The scattering of a flying photon by a two-level system ultrastrongly coupled to a one-dimensional photonic waveguide is studied numerically. The photonic medium is modeled as an array of coupled cavities and the whole system is analyzed beyond the rotating wave approximation using matrix product states. It is found that the scattering is strongly influenced by the single- and multiphoton dressed bound states present in the system. In the ultrastrong coupling regime a new channel for inelastic scattering appears, where an incident photon deposits energy into the qubit, exciting a photon-bound state, and escaping with a lower frequency. This single-photon nonlinear frequency conversion process can reach up to 50% efficiency. Other remarkable features in the scattering induced by counterrotating terms are a blueshift of the reflection resonance and a Fano resonance due to long-lived excited states.

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

    KAUST Repository

    Zhang, Qiang


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

  8. First results of electron temperature measurements by the use of multi-pass Thomson scattering system in GAMMA 10

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, M., E-mail:; Nagasu, K.; Shimamura, Y.; Shima, Y.; Kohagura, J.; Sakamoto, M.; Nakashima, Y.; Imai, T.; Ichimura, M. [Plasma Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Yasuhara, R.; Yamada, I.; Funaba, H.; Kawahata, K. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Minami, T. [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)


    A multi-pass Thomson scattering (TS) has the advantage of enhancing scattered signals. We constructed a multi-pass TS system for a polarisation-based system and an image relaying system modelled on the GAMMA 10 TS system. We undertook Raman scattering experiments both for the multi-pass setting and for checking the optical components. Moreover, we applied the system to the electron temperature measurements in the GAMMA 10 plasma for the first time. The integrated scattering signal was magnified by approximately three times by using the multi-pass TS system with four passes. The electron temperature measurement accuracy is improved by using this multi-pass system.

  9. Time-resolved X-ray scattering by electronic wave packets: analytic solutions to the hydrogen atom

    DEFF Research Database (Denmark)

    Simmermacher, Mats; Henriksen, Niels Engholm; Møller, Klaus Braagaard


    description of time-resolved X-ray scattering by non-stationary electronic wave packets in atomic systems. A consistent application of the Waller-Hartree approximation is discussed and different contributions to the total differential scattering signal are identified and interpreted. Moreover......, it is demonstrated how the scattering signal of wave packets in the hydrogen atom can be expressed analytically. This permits simulations without numerical integration and establishes a benchmark for both efficiency and accuracy. Based on that, scattering patterns of an exemplary wave packet in the hydrogen atom...

  10. Heavy-ion nucleus scattering

    CERN Document Server

    Rahman, M A; Haque, S


    Heavy ion-nucleus scattering is an excellent laboratory to probe high spin phenomena, exotic nuclei and for the analysis of various exit channels. The Strong Absorption Model or the generalized diffraction models, which are semi-classical in nature, have been employed in the description of various heavy ion-nucleus scattering phenomena with reasonable success. But one needs to treat the deflection function (scattering angles) quantum mechanically in the Wave Mechanical picture for the appropriate description of the heavy-ion nucleus scattering phenomena. We have brought the mathematics for the cross-section of the heavy-ion nucleus scattering to an analytic expression taking account of the deflection function (scattering angles) quantum mechanically. sup 9 Be, sup 1 sup 6 O, sup 2 sup 0 Ne and sup 3 sup 2 S heavy-ion beams elastic scattering from sup 2 sup 8 Si, sup 2 sup 4 Mg and sup 4 sup 0 Ca target nuclei at various projectile energies over the range 20-151 MeV have been analysed in terms of the 2-paramet...

  11. Scattering of electromagnetic waves by obstacles

    CERN Document Server

    Kristensson, Gerhard


    The main purpose of Scattering of Electromagnetic Waves by Obstacles is to give a theoretical treatment of the scattering phenomena, and to illustrate numerical computations of some canonical scattering problems for different geometries and materials.

  12. Baseline-Subtraction-Free (BSF) Damage-Scattered Wave Extraction for Stiffened Isotropic Plates (United States)

    He, Jiaze; Leser, Patrick E.; Leser, William P.


    Lamb waves enable long distance inspection of structures for health monitoring purposes. However, this capability is diminished when applied to complex structures where damage-scattered waves are often buried by scattering from various structural components or boundaries in the time-space domain. Here, a baseline-subtraction-free (BSF) inspection concept based on the Radon transform (RT) is proposed to identify and separate these scattered waves from those scattered by damage. The received time-space domain signals can be converted into the Radon domain, in which the scattered signals from structural components are suppressed into relatively small regions such that damage-scattered signals can be identified and extracted. In this study, a piezoelectric wafer and a linear scan via laser Doppler vibrometer (LDV) were used to excite and acquire the Lamb-wave signals in an aluminum plate with multiple stiffeners. Linear and inverse linear Radon transform algorithms were applied to the direct measurements. The results demonstrate the effectiveness of the Radon transform as a reliable extraction tool for damage-scattered waves in a stiffened aluminum plate and also suggest the possibility of generalizing this technique for application to a wide variety of complex, large-area structures.

  13. Light scattering reviews 9 light scattering and radiative transfer

    CERN Document Server

    Kokhanovsky, Alexander A


    This book details modern methods of the radiative transfer theory. It presents recent advances in light scattering (measurements and theory) and highlights the newest developments in remote sensing of aerosol and cloud properties.

  14. Nuclear resonance scattering study of iridates, iridium and antimony based pyrochlores

    Energy Technology Data Exchange (ETDEWEB)

    Alexeev, P.


    This thesis shows the first synchrotron-based Moessbauer spectroscopy studies on iridium containing compounds and first vibrational spectroscopy on Sb containing compounds carried out at the P01 beamline of PETRA III. In this context, two types of X-ray monochromators have been developed: a monochromator for 73 keV photons with medium energy resolution, and a high-resolution backscattering monochromator based on a sapphire crystal. The monochromator for 73 keV X-rays is the key instrument for hyperfine spectroscopy on Iridium compounds, while the sapphire backscattering monochromator is purposed to vibrational spectroscopy on any Moessbauer resonances with the transition energies in the 20-50 keV range. Additionally, the signal detection for nuclear resonance scattering experiments at the beamline was significantly improved during this work, inspired by the high energies and low lifetimes of the employed resonances. The first synchrotron-based hyperfine spectroscopy on Iridium-containing compounds was demonstrated by NRS on 73 keV resonance in {sup 193}Ir. The results can be interpreted by dynamical theory of nuclear resonance scattering. In this work, special emphasis is set onto the electronic and magnetic properties of Ir nuclei in IrO{sub 2} and in Ruddlesden-Popper (RP) phases of strontium iridates Sr{sub n+1}Ir{sub n}O{sub 3n+1} (n=0,1). These systems are well-suited for studies with X-ray scattering techniques, since the scattered signal contains vast information about the widely tunable crystallographic and electronic structure of these systems; furthermore, studies with X-rays are less limited by absorption from iridium as it is the case for neutron scattering experiments. The hyperfine parameters in IrO{sub 2}, SrIrO{sub 3} and Sr{sub 2}IrO{sub 4} have been measured via Nuclear Forward Scattering for the first time. Using the dynamical theory of NRS, the temperature and magnetic field dependence of the electric field gradient and magnetic hyperfine field

  15. Global diagnostics of the ionospheric perturbations related to the seismic activity using the VLF radio signals collected on the DEMETER satellite

    Directory of Open Access Journals (Sweden)

    O. Molchanov


    Full Text Available The analysis of the VLF signals radiated by ground transmitters and received on board of the French DEMETER satellite, reveals a drop of the signals (scattering spot connected with the occurrence of large earthquakes. The extension of the "scattering spots" zone is large enough (1000–5000 km and, probably, it increases with the magnitude of the "relative" earthquake. A possible model to explain the phenomenology, based on the acoustic gravity waves and the ionosphere turbulence, is proposed. The method of diagnostics applied to this study has the advantage to be a global one due to the world wide location of the powerful VLF transmitters and of the satellite reception. However, a specific disadvantage exists because the method requires rather a long time period of analysis due to the large longitudinal displacements among the successive satellite orbits. At the moment, at least, one month seems to be necessary.

  16. Parity nonconserving asymmetry in neutron-deuteron and proton-deuteron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kloet, W.M.; Gibson, B.F.; Stephenson, G.J. Jr.; Henley, E.M.


    Parity nonconservation in nucleon (N )-deuteron(d) scattering is examined at low energies (< or =40 MeV), particularly at 15 MeV. A Faddeev treatment is employed. For the strong N-N force a separable interaction, which fits scattering cross sections up to 60--100 MeV, is used; for the weak parity nonconserving NN force, an isoscalar short range term due to rho and exchanges and an isovector pion exchange contribution are included. Comparisons with parity nonconserving experimental asymmetries in NN scattering are made. For the parity nonconserving asymmetry in N-d scattering the contributions of various terms are separated, so that the model dependence of our results can be discussed. It is found that multiple scattering effects are important. The energy dependence of the parity nonconserving asymmetry in N-d scattering is found to differ qualitatively from that in NN scattering.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  18. Synthetic Fourier transform light scattering. (United States)

    Lee, Kyeoreh; Kim, Hyeon-Don; Kim, Kyoohyun; Kim, Youngchan; Hillman, Timothy R; Min, Bumki; Park, Yongkeun


    We present synthetic Fourier transform light scattering, a method for measuring extended angle-resolved light scattering (ARLS) from individual microscopic samples. By measuring the light fields scattered from the sample plane and numerically synthesizing them in Fourier space, the angle range of the ARLS patterns is extended up to twice the numerical aperture of the imaging system with unprecedented sensitivity and precision. Extended ARLS patterns of individual microscopic polystyrene beads, healthy human red blood cells (RBCs), and Plasmodium falciparum-parasitized RBCs are presented.

  19. A Discrete Scatterer Technique for Evaluating Electromagnetic Scattering from Trees (United States)


    distribution is unlimited. 1 1. Introduction Developing sensing capabilities for the detection of ground targets concealed in a forest environment...scatterer simulation are 369 MB and 33 min/frequency, respectively, on a Dell Precision T7500 workstation with Intel Xeon CPU of 2.67 GHz, while those...2. Thirion L, Colin E, Dahon C. Capabilities of a forest coherent scattering model applied to radiometry, interferometry, and polarimetry at P

  20. Neutron scatter camera (United States)

    Mascarenhas, Nicholas; Marleau, Peter; Brennan, James S.; Krenz, Kevin D.


    An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4.pi.. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

  1. Elastodynamic wave scattering by finite-sized resonant scatterers at the surface of a horizontally layered halfspace. (United States)

    Lombaert, Geert; Clouteau, Didier


    The present paper deals with the multiple scattering by randomly distributed elastodynamic systems at the surface of a horizontally layered elastic halfspace due to an incident plane wave. Instead of solving this problem for a particular configuration of the system, multiple scattering theory is used to compute the ensemble response statistics. The Dyson equation is used to calculate the mean field, while the nonstationary second order statistics are obtained by means of the Bethe-Salpeter equation. This allows for the determination of the mean square response of the system in the time and frequency domains. This model is used to study multiple scattering between buildings under seismic excitation. The influence of multiple scattering on the seismic site response is verified. Furthermore, the influence of the footprint and the damping of the buildings are investigated. The results are compared to results of a coupled finite element/boundary element solution for a group of buildings.

  2. Predator and prey perception in copepods due to hydromechanical signals

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Visser, Andre


    large and rapidly swimming/sinking prey particles, and (4) that the model can accommodate the 3 orders of magnitude variation in clearance rates observed in the copepod Oithona similis feeding on motile protists and sinking particles. We finally discuss the implications of hydromechanical predator...... and prey perception to trophic interactions and vertical particle fluxes, and suggest important research questions that may be addressed....

  3. Collective phenomena in pp and ep scattering (United States)

    Celiberto, Francesco Giovanni; Fiore, Roberto; Jenkovszky, László


    Bjorken scaling violation in deep inelastic electron-proton scattering (DIS) is related to the rise of hadronic cross sections by using the additive quark model. Of special interest is the connection between saturation in the low-x behavior of the DIS structure functions (SF) and possible slow-down of the pp cross section rise due to saturation effects. We also identify saturation effects in the DIS SF with phase transition that can be described by the Van der Waals equation of state.

  4. Electromagnetic Scattering in Micro- and Nanostructured Materials

    DEFF Research Database (Denmark)

    de Lasson, Jakob Rosenkrantz

    The research fields of optical microstructures and plasmonic nanostructures are particularly active these years, and interesting applications in, e.g., quantum information technology in the former and novel types of solar cells in the latter, drive the investigations. Central in both fields...... dipoles, which is often alluded to in the literature, breaks down in the limit of closely spaced scattering objects. The study of metallic nanoparticles is particularly intriguing when these are in close proximity, due to the coupling of their near-fields, and the breakdown of the simpler approach reveals...

  5. Geometric phase coded metasurface: from polarization dependent directive electromagnetic wave scattering to diffusion-like scattering. (United States)

    Chen, Ke; Feng, Yijun; Yang, Zhongjie; Cui, Li; Zhao, Junming; Zhu, Bo; Jiang, Tian


    Ultrathin metasurface compromising various sub-wavelength meta-particles offers promising advantages in controlling electromagnetic wave by spatially manipulating the wavefront characteristics across the interface. The recently proposed digital coding metasurface could even simplify the design and optimization procedures due to the digitalization of the meta-particle geometry. However, current attempts to implement the digital metasurface still utilize several structural meta-particles to obtain certain electromagnetic responses, and requiring time-consuming optimization especially in multi-bits coding designs. In this regard, we present herein utilizing geometric phase based single structured meta-particle with various orientations to achieve either 1-bit or multi-bits digital metasurface. Particular electromagnetic wave scattering patterns dependent on the incident polarizations can be tailored by the encoded metasurfaces with regular sequences. On the contrast, polarization insensitive diffusion-like scattering can also been successfully achieved by digital metasurface encoded with randomly distributed coding sequences leading to substantial suppression of backward scattering in a broadband microwave frequency. The proposed digital metasurfaces provide simple designs and reveal new opportunities for controlling electromagnetic wave scattering with or without polarization dependence.

  6. Laser light scattering basic principles and practice

    CERN Document Server

    Chu, Benjamin


    Geared toward upper-level undergraduate and graduate students, this text introduces the interdisciplinary area of laser light scattering, focusing chiefly on theoretical concepts of quasielastic laser scattering.

  7. Impact Wave Monitoring in Soil Using a Dynamic Fiber Sensor Based on Stimulated Brillouin Scattering

    Directory of Open Access Journals (Sweden)

    Qingsong Cui


    Full Text Available The impact wave response of soil due to a ball drop is monitored on a 30.5 cm by 30.5 cm square soil box using a fiber sensor with dynamic strain sensing capability. The experiments are conducted in real time using a simple one-laser one-modulator configuration with stimulated Brillouin scattering. The embedded BOTDA sensor grid successfully monitored the distribution and evolution of the inner strains of a sand bed during a mass impact on its surface. The measurement of the distributed dynamic strains was possible in several milliseconds and with 1 cm actual location resolution. This paper presents a time-domain signal analysis utilized for determining the dynamic strains in embedded fiber sensor. The results demonstrate the method to be a promising one for detection of subsurface vibration and movement in geotechnical Structure Health Monitoring (SHM.

  8. Scattering of light by crystals

    CERN Document Server

    Hayes, William


    This authoritative graduate-level text describes inelastic light scattering by crystals and its use in the investigation of solid-state excitation, with experimental techniques common to all types of excitation. 1978 edition.

  9. Integration rules for scattering equations

    Energy Technology Data Exchange (ETDEWEB)

    Baadsgaard, Christian; Bjerrum-Bohr, N.E.J.; Bourjaily, Jacob L.; Damgaard, Poul H. [Niels Bohr International Academy and Discovery Center,Niels Bohr Institute, University of Copenhagen,Blegdamsvej 17, DK-2100 Copenhagen Ø (Denmark)


    As described by Cachazo, He and Yuan, scattering amplitudes in many quantum field theories can be represented as integrals that are fully localized on solutions to the so-called scattering equations. Because the number of solutions to the scattering equations grows quite rapidly, the contour of integration involves contributions from many isolated components. In this paper, we provide a simple, combinatorial rule that immediately provides the result of integration against the scattering equation constraints for any Möbius-invariant integrand involving only simple poles. These rules have a simple diagrammatic interpretation that makes the evaluation of any such integrand immediate. Finally, we explain how these rules are related to the computation of amplitudes in the field theory limit of string theory.

  10. Light Scattering in Solid IX

    CERN Document Server

    Cardona, Manuel


    This is the ninth volume of a well-established series in which expert practitioners discuss topical aspects of light scattering in solids. It reviews recent developments concerning mainly semiconductor nanostructures and inelastic x-ray scattering, including both coherent time-domain and spontaneous scattering studies. In the past few years, light scattering has become one of the most important research and characterization methods for studying carbon nanotubes and semiconducting quantum dots, and a crucial tool for exploring the coupled exciton--photon system in semiconductor cavities. Among the novel techniques discussed in this volume are pump--probe ultrafast measurements and those which use synchrotron radiation as light source. The book addresses improvements in the intensity, beam quality and time synchronization of modern synchrotron sources, which made it possible to measure the phonon dispersion in very small samples and to determine electronic energy bands as well as enabling real-time observations...

  11. Compton scattering at high intensities

    Energy Technology Data Exchange (ETDEWEB)

    Heinzl, Thomas, E-mail: [University of Plymouth, School of Mathematics and Statistics, Drake Circus, Plymouth PL4 8AA (United Kingdom)


    High-intensity Compton scattering takes place when an electron beam is brought into collision with a high power laser. We briefly review the main intensity signatures using the formalism of strong-field quantum electrodynamics.

  12. Neutron scattering and models: Titanium

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B.


    Differential neutron elastic-scattering cross sections of elemental titanium were measured from 4.5 {r_arrow} 10.0 MeV in incident energy increments of {approx} 0.5 MeV. At each energy the measurements were made at forty or more scattering angles distributed between {approx} 17 and 160{degree}. Concurrently, differential neutron inelastic-scattering cross sections were measured for observed excitations of 0.975 {+-} 0.034, 1.497 {+-} 0.033, 2.322 {+-} 0.058, 3.252 {+-} 0.043, 3.700 {+-} 0.093, 4.317 {+-} 0.075 and 4.795 {+-} 0.100 MeV. All of the observed inelastically-scattered neutron groups were composites of contributions from several isotopes and/or levels. The experimental results were used to develop energy-average optical, statistical and coupled-channels models.

  13. Modeling fluctuations in scattered waves

    CERN Document Server

    Jakeman, E


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

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

    Sarabandi, Kamal

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

  15. Radar interferometry persistent scatterer technique

    CERN Document Server

    Kampes, Bert M


    This volume is devoted to the Persistent Scatterer Technique, the latest development in radar interferometric data processing. It is the only book on Permanent Scatterer (PS) technique of radar interferometry, and it details a newly developed stochastic model and estimator algorithm to cope with possible problems for the application of the PS technique. The STUN (spatio-temporal unwrapping network) algorithm, developed to cope with these issues in a robust way, is presented and applied to two test sites.

  16. Isogeometric analysis of acoustic scattering


    Venås, Jon Vegard


    Acoustic scattering has been thoroughly analyzed with the use of finite element analysis (FEA). The problem at hand is a coupled fluid-structure interaction problem on an unbounded domain, where an object of elastic material is surrounded by fluid. Using physical assumptions, the fluid is described by the wave equation which is transformed to the Helmholtz equation. That is, the frequency domain is considered instead of the time domain. In particular one is interested in the scattered pressur...

  17. Double parton scattering in CMS

    CERN Document Server

    Sunar Cerci, Deniz


    Recent results on the double parton scattering measurements performed using the proton-proton collision data collected with the CMS detector are presented. The observables, which are sensitive to double parton scattering, are investigated after being corrected for detector effects and selection efficiencies. Multivariate analysis techniques are used for increasing the sensitivity. The effective cross section, $\\sigma_{eff}$ is also extracted using different processes at various center-of-mass energies.

  18. RCCC calculations for electron scattering on quasi-two electron targets (United States)

    Bostock, C.; Fursa, D. V.; Bray, I.


    We report on the recent extension of the RCCC method to accommodate electron scattering from quasi-two electron targets. We present results for electron scattering from mercury (Z = 80) which serves as a testing ground for relativistic theories due to its high atomic number. Furthermore electron-mercury scattering plays an important practical role in the physics of fluorescent and high intensity discharge lamps.

  19. A Stimulated Raman Scattering CMOS Pixel Using a High-Speed Charge Modulator and Lock-in Amplifier

    Directory of Open Access Journals (Sweden)

    De Xing Lioe


    Full Text Available A complementary metal-oxide semiconductor (CMOS lock-in pixel to observe stimulated Raman scattering (SRS using a high speed lateral electric field modulator (LEFM for photo-generated charges and in-pixel readout circuits is presented. An effective SRS signal generated after the SRS process is very small and needs to be extracted from an extremely large offset due to a probing laser signal. In order to suppress the offset components while amplifying high-frequency modulated small SRS signal components, the lock-in pixel uses a high-speed LEFM for demodulating the SRS signal, resistor-capacitor low-pass filter (RC-LPF and switched-capacitor (SC integrator with a fully CMOS differential amplifier. AC (modulated components remained in the RC-LPF outputs are eliminated by the phase-adjusted sampling with the SC integrator and the demodulated DC (unmodulated components due to the SRS signal are integrated over many samples in the SC integrator. In order to suppress further the residual offset and the low frequency noise (1/f noise components, a double modulation technique is introduced in the SRS signal measurements, where the phase of high-frequency modulated laser beam before irradiation of a specimen is modulated at an intermediate frequency and the demodulation is done at the lock-in pixel output. A prototype chip for characterizing the SRS lock-in pixel is implemented and a successful operation is demonstrated. The reduction effects of residual offset and 1/f noise components are confirmed by the measurements. A ratio of the detected small SRS to offset a signal of less than 10−5 is experimentally demonstrated, and the SRS spectrum of a Benzonitrile sample is successfully observed.

  20. A Stimulated Raman Scattering CMOS Pixel Using a High-Speed Charge Modulator and Lock-in Amplifier. (United States)

    Lioe, De Xing; Mars, Kamel; Kawahito, Shoji; Yasutomi, Keita; Kagawa, Keiichiro; Yamada, Takahiro; Hashimoto, Mamoru


    A complementary metal-oxide semiconductor (CMOS) lock-in pixel to observe stimulated Raman scattering (SRS) using a high speed lateral electric field modulator (LEFM) for photo-generated charges and in-pixel readout circuits is presented. An effective SRS signal generated after the SRS process is very small and needs to be extracted from an extremely large offset due to a probing laser signal. In order to suppress the offset components while amplifying high-frequency modulated small SRS signal components, the lock-in pixel uses a high-speed LEFM for demodulating the SRS signal, resistor-capacitor low-pass filter (RC-LPF) and switched-capacitor (SC) integrator with a fully CMOS differential amplifier. AC (modulated) components remained in the RC-LPF outputs are eliminated by the phase-adjusted sampling with the SC integrator and the demodulated DC (unmodulated) components due to the SRS signal are integrated over many samples in the SC integrator. In order to suppress further the residual offset and the low frequency noise (1/f noise) components, a double modulation technique is introduced in the SRS signal measurements, where the phase of high-frequency modulated laser beam before irradiation of a specimen is modulated at an intermediate frequency and the demodulation is done at the lock-in pixel output. A prototype chip for characterizing the SRS lock-in pixel is implemented and a successful operation is demonstrated. The reduction effects of residual offset and 1/f noise components are confirmed by the measurements. A ratio of the detected small SRS to offset a signal of less than 10(-)⁵ is experimentally demonstrated, and the SRS spectrum of a Benzonitrile sample is successfully observed.

  1. Imaging X-ray Thomson Scattering Spectrometer Design and Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Gamboa, E.J. [University of Michigan; Huntington, C.M. [University of Michigan; Trantham, M.R. [University of Michigan; Keiter, P.A [University of Michigan; Drake, R.P. [University of Michigan; Montgomery, David [Los Alamos National Laboratory; Benage, John F. [Los Alamos National Laboratory; Letzring, Samuel A. [Los Alamos National Laboratory


    In many laboratory astrophysics experiments, intense laser irradiation creates novel material conditions with large, one-dimensional gradients in the temperature, density, and ionization state. X-ray Thomson scattering is a powerful technique for measuring these plasma parameters. However, the scattered signal has previously been measured with little or no spatial resolution, which limits the ability to diagnose inhomogeneous plasmas. We report on the development of a new imaging x-ray Thomson spectrometer (IXTS) for the Omega laser facility. The diffraction of x-rays from a toroidally-curved crystal creates high-resolution images that are spatially resolved along a one-dimensional profile while spectrally dispersing the radiation. This focusing geometry allows for high brightness while localizing noise sources and improving the linearity of the dispersion. Preliminary results are presented from a scattering experiment that used the IXTS to measure the temperature profile of a shocked carbon foam.

  2. Scattered light characterization of FORTIS (United States)

    McCandliss, Stephan R.; Carter, Anna; Redwine, Keith; Teste, Stephane; Pelton, Russell; Hagopian, John; Kutyrev, Alexander; Li, Mary J.; Moseley, S. Harvey


    We describe our efforts to build a Wide-Field Lyman alpha Geocoronal simulator (WFLaGs) for characterizing the end-to-end sensitivity of FORTIS (Far-UV Off Rowland-circle Telescope for Imaging and Spectroscopy) to scattered Lyman α emission from outside of the nominal (1/2 degree)2 field-of-view. WFLaGs is a 50 mm diameter F/1 aluminum parabolic collimator fed by a hollow cathode discharge lamp with a 80 mm clear MgF2 window housed in a vacuum skin. It creates emission over a 10 degree FOV. WFLaGS will allow us to validate and refine a recently developed scattered light model and verify our scatter light mitigation strategies, which will incorporate low scatter baffle materials, and possibly 3-d printed light traps, covering exposed scatter centers. We present measurements of scattering intensity of Lyman alpha as a function of angle with respect to the specular reflectance direction for several candidate baffle materials. Initial testing of WFLaGs will be described.

  3. Urticaria due to antihistamines

    National Research Council Canada - National Science Library

    Sánchez Morillas, L; Rojas Pérez-Ezquerra, P; Reaño Martos, M; Sanz, M L; Laguna Martínez, J J


    .... We report a patient with urticaria due to ingestion of ebastine and fexofenadine. Skin prick tests, patch tests, and basophil activation tests with the implicated drugs and antihistamines from other families were negative...

  4. Quasiparticle scattering from a double vortex scatterer in d-wave superconductors (United States)

    Ganeshan, Sriram; Kulkarni, Manas; Durst, Adam C.


    The low energy quasiparticle excitations of a d-wave superconductor are massless Dirac fermions. In the presence of a magnetic field, the scattering of quasiparticles from vortices receives both a superflow contribution, due to interaction with the superflow circulating about each vortex, as well as a Berry phase contribution, due to the Berry phase acquired upon circling a vortex. Calculating the cross section for quasiparticle scattering from a double vortex provides a clean way of isolating and studying the two effects. We do so by making use of elliptical coordinates, a natural setting for studying this two-center problem. With proper gauge choice, the Berry phase contribution takes the form of a branch cut between vortex centers, providing a boundary condition for the spinor wave function across the line segment joining the foci of the elliptical coordinate system. We solve the quantum scattering of Dirac quasiparticles in elliptical coordinates. Our approach is to separate the free Dirac equation in elliptical coordinates. The separated angular and radial functions turn out to be the solutions of angular and modified Whittaker-Hill's equations. We summarize the technique to expand incident plane wave spinor in terms of Whittaker-Hill functions. We also present the asymptotic form of the separated solutions in order to setup an analytical formula for differential cross section.

  5. Nd:YAG Laser-Based Dual-Line Detection Rayleigh Scattering and Current Efforts on UV, Filtered Rayleigh Scattering (United States)

    Otugen, M. Volkan; Popovic, Svetozar


    Ongoing research in Rayleigh scattering diagnostics for variable density low speed flow applications and for supersonic flow measurements are described. During the past several years, the focus has been on the development and use of a Nd:YAG-based Rayleigh scattering system with improved signal-to-noise characteristics and with applicability to complex, confined flows. This activity serves other research projects in the Aerodynamics Laboratory which require the non-contact, accurate, time-frozen measurement of gas density, pressure, and temperature (each separately), in a fairly wide dynamic range of each parameter. Recently, with the acquisition of a new seed-injected Nd:YAG laser, effort also has been directed to the development of a high-speed velocity probe based on a spectrally resolved Rayleigh scattering technique.

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

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


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

  7. Molecular sensitivity on graphene decorated with noble metal nanoparticles: Graphene-mediated surface-enhanced Raman scattering (G-SERS) substrates (United States)

    Gupta, Sanju; Banaszak, Alexander; Smith, Tyler

    Raman scattering signal enhancement that uses graphene as support, graphene-enhanced Raman scattering (G-SERS), is a recent phenomenon. While SERS enhancement arises due to electromagnetic mechanism, G-SERS also relies on chemical mechanism and therefore it shows unique molecular sensitivity. In this work, we developed graphene materials decorated with silver and gold nanoparticles for detecting methylene blue (MB) and rhodamine 6G (Rh6G) in view of optical and biological importance. The results illustrate that silver and gold nanoparticles immobilized on multilayer graphene graphene oxide and reduced graphene oxide significantly enhance the signal, and as cascaded amplification of SERS signal on multilayer architecture, larger than those only on metal nanoparticles. The sensitivity can be tuned by controlling the size of nanoparticles and the highest SERS enhancement factor (four orders) is achieved at optimal 30 nm silver and 40 nm gold nanoparticles on reduced graphene oxide and multilayer graphene. They serve as `smart' SERS platforms capable of detecting MB and Rh6G below 10 pM concentration. The enhancement is discussed in 1. molecular structures (molecular symmetry; face-down and edge-on) 2. charge-transfer interaction between molecules and graphene and 3. graphene-metal nanoparticle interfacial hybridization. The signal enhancement is supported by change in UV-vis absorption spectra of molecules in contact with graphene guiding molecular detection and biotechnology. KY NSF EPSCoR.

  8. A drift chamber tracking system for muon scattering tomography applications (United States)

    Burns, J.; Quillin, S.; Stapleton, M.; Steer, C.; Snow, S.


    Muon scattering tomography (MST) allows the identification of shielded high atomic number (high-Z) materials by measuring the scattering angle of cosmic ray muons passing through an inspection region. Cosmic ray muons scatter to a greater degree due to multiple Coulomb scattering in high-Z materials than low-Z materials, which can be measured as the angular difference between the incoming and outgoing trajectories of each muon. Measurements of trajectory are achieved by placing position sensitive particle tracking detectors above and below the inspection volume. By localising scattering information, the point at which a series of muons scatter can be used to reconstruct an image, differentiating high, medium and low density objects. MST is particularly useful for differentiating between materials of varying density in volumes that are difficult to inspect visually or by other means. This paper will outline the experimental work undertaken to develop a prototype MST system based on drift chamber technology. The planar drift chambers used in this prototype measure the longitudinal interaction position of an ionising particle from the time taken for elections, liberated in the argon (92.5%), carbon dioxide (5%), methane (2.5%) gas mixture, to reach a central anode wire. Such a system could be used to enhance the detection of shielded radiological material hidden within regular shipping cargo.

  9. First operations with the new Collective Thomson Scattering diagnostic on the Frascati Tokamak Upgrade device

    DEFF Research Database (Denmark)

    Bin, W.; Bruschi, A.; D'Arcangelo, O.


    Anomalous emissions were found over the last few years in spectra of Collective Thomson Scattering (CTS) diagnostics in tokamak devices such as TEXTOR, ASDEX and FTU, in addition to real CTS signals. The signal frequency, down-shifted with respect to the probing one, suggested a possible origin...

  10. Rapid-scan Fourier-transform coherent anti-Stokes Raman scattering spectroscopy with heterodyne detection. (United States)

    Hiramatsu, Kotaro; Luo, Yizhi; Ideguchi, Takuro; Goda, Keisuke


    High-speed Raman spectroscopy has become increasingly important for analyzing chemical dynamics in real time. To address the need, rapid-scan Fourier-transform coherent anti-Stokes Raman scattering (FT-CARS) spectroscopy has been developed to realize broadband CARS measurements at a scan rate of more than 20,000 scans/s. However, the detection sensitivity of FT-CARS spectroscopy is inherently low due to the limited number of photons detected during each scan. In this Letter, we show our experimental demonstration of enhanced sensitivity in rapid-scan FT-CARS spectroscopy by heterodyne detection. Specifically, we implemented heterodyne detection by superposing the CARS electric field with an external local oscillator (LO) for their interference. The CARS signal was amplified by simply increasing the power of the LO without the need for increasing the incident power onto the sample. Consequently, we achieved enhancement in signal intensity and the signal-to-noise ratio by factors of 39 and 5, respectively, compared to FT-CARS spectroscopy with homodyne detection. The sensitivity-improved rapid-scan FT-CARS spectroscopy is expected to enable the sensitive real-time observation of chemical dynamics in a broad range of settings, such as combustion engines and live biological cells.

  11. Bound state in positron scattering by allene (United States)

    Barbosa, Alessandra Souza; Sanchez, Sergio d'Almeida; Bettega, Márcio H. F.


    We report integral and differential cross sections for positron collisions with allene, calculated with the Schwinger multichannel method. The cross sections were computed in the static-polarization approximation for energies up to 7 eV. We have tested a series of single-particle basis sets and different polarization schemes to improve the description of low-energy positron scattering by the allene molecule. We have found that the use of extra centers with no net charge with additional single-particle s - and p -type functions centered at them are essential in order to accurately reproduce the polarization potential and, hence, obtain proper scattering cross sections. The choice of the allene molecule was due to the fact that it is a highly symmetric molecule with no permanent dipole moment and would allow several different calculations. Our cross sections are compared to the available experimental data for the total cross section with a reasonable agreement after correcting their results due to the low angular discrimination of their apparatus. Also, a virtual state was observed in the integral cross section that became a bound state when the description of the polarization potential is improved. We also observed a Ramsauer-Townsend minimum in the cross section whose location varies from 2.7 to 3.4 eV, depending on the polarization scheme used in the calculations.

  12. Gated integrator PXI-DAQ system for Thomson scattering diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Kiran, E-mail:; Pillai, Vishal; Singh, Neha; Thomas, Jinto; Kumar, Ajai


    Gated Integrator (GI) PXI based data acquisition (DAQ) system has been designed and developed for the ease of acquiring fast Thomson Scattered signals (∼50 ns pulse width). The DAQ system consists of in-house designed and developed GI modules and PXI-1405 chassis with several PXI-DAQ modules. The performance of the developed system has been validated during the SST-1 campaigns. The dynamic range of the GI module depends on the integrating capacitor (C{sub i}) and the modules have been calibrated using 12 pF and 27 pF integrating capacitors. The developed GI module based data acquisition system consists of sixty four channels for simultaneous sampling using eight PXI based digitization modules having eight channels per module. The error estimation and functional tests of this unit are carried out using standard source and also with the fast detectors used for Thomson scattering diagnostics. User friendly Graphical User Interface (GUI) has been developed using LabVIEW on Windows platform to control and acquire the Thomson scattering signal. A robust, easy to operate and maintain with low power consumption, having higher dynamic range with very good sensitivity and cost effective DAQ system is developed and tested for the SST-1 Thomson scattering diagnostics.

  13. Refraction and Faraday rotation in the incoherent scatter radar technique (United States)

    Shpynev, Boris G.


    In this paper we consider the radiolocation equation for the incoherent scatter radar (ISR) method; the equation accounts for refraction effect and Faraday rotation in the VHF frequency domain. Our research shows that we cannot ignore refraction in processing the incoherent scatter data when lag-product is used to obtain the ionospheric characteristics. Effect of refraction can explain some uncertainties that arise during processing and interpretation of the ISR data. This effect shows that together with the "ion line" of incoherent scatter spectrum, a relatively small "electron line" also plays a significant role in forming the ionosphere response. The "electron line" behaves as an additional "radar induced" wideband radiolocation signal affected by refraction and Faraday rotation; it depends on the ionosphere temperature and ion composition. The presence of a wideband "electron line" produces specific distortions of the ISR spectrum during 3D-forming of the ionosphere response inside the ISR antenna diagram pattern. During testing, we found that the signal from the ISR "electron line" can be measured at much higher altitudes comparing to the "ion line." Hence, to improve the incoherent scatter technique, we can take the "electron line" and refraction into account.

  14. Signaling aggression. (United States)

    van Staaden, Moira J; Searcy, William A; Hanlon, Roger T


    From psychological and sociological standpoints, aggression is regarded as intentional behavior aimed at inflicting pain and manifested by hostility and attacking behaviors. In contrast, biologists define aggression as behavior associated with attack or escalation toward attack, omitting any stipulation about intentions and goals. Certain animal signals are strongly associated with escalation toward attack and have the same function as physical attack in intimidating opponents and winning contests, and ethologists therefore consider them an integral part of aggressive behavior. Aggressive signals have been molded by evolution to make them ever more effective in mediating interactions between the contestants. Early theoretical analyses of aggressive signaling suggested that signals could never be honest about fighting ability or aggressive intentions because weak individuals would exaggerate such signals whenever they were effective in influencing the behavior of opponents. More recent game theory models, however, demonstrate that given the right costs and constraints, aggressive signals are both reliable about strength and intentions and effective in influencing contest outcomes. Here, we review the role of signaling in lieu of physical violence, considering threat displays from an ethological perspective as an adaptive outcome of evolutionary selection pressures. Fighting prowess is conveyed by performance signals whose production is constrained by physical ability and thus limited to just some individuals, whereas aggressive intent is encoded in strategic signals that all signalers are able to produce. We illustrate recent advances in the study of aggressive signaling with case studies of charismatic taxa that employ a range of sensory modalities, viz. visual and chemical signaling in cephalopod behavior, and indicators of aggressive intent in the territorial calls of songbirds. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. High energy gravitational scattering: a numerical study

    CERN Document Server

    Marchesini, Giuseppe


    The S-matrix in gravitational high energy scattering is computed from the region of large impact parameters b down to the regime where classical gravitational collapse is expected to occur. By solving the equation of an effective action introduced by Amati, Ciafaloni and Veneziano we find that the perturbative expansion around the leading eikonal result diverges at a critical value signalling the onset of a new regime. We then discuss the main features of our explicitly unitary S-matrix down to the Schwarzschild's radius R=2G s^(1/2), where it diverges at a critical value b ~ 2.22 R of the impact parameter. The nature of the singularity is studied with particular attention to the scaling behaviour of various observables at the transition. The numerical approach is validated by reproducing the known exact solution in the axially symmetric case to high accuracy.

  16. Stimulated Brillouin scatter and stimulated ion Bernstein scatter during electron gyroharmonic heating experiments (United States)

    Fu, H.; Scales, W. A.; Bernhardt, P. A.; Samimi, A.; Mahmoudian, A.; Briczinski, S. J.; McCarrick, M. J.


    Results of secondary radiation, Stimulated Electromagnetic Emission (SEE), produced during ionospheric modification experiments using ground-based high-power radio waves are reported. These results obtained at the High Frequency Active Auroral Research Program (HAARP) facility specifically considered the generation of Magnetized Stimulated Brillouin Scatter (MSBS) and Stimulated Ion Bernstein Scatter (SIBS) lines in the SEE spectrum when the transmitter frequency is near harmonics of the electron gyrofrequency. The heater antenna beam angle effect was investigated on MSBS in detail and shows a new spectral line postulated to be generated near the upper hybrid resonance region due to ion acoustic wave interaction. Frequency sweeping experiments near the electron gyroharmonics show for the first time the transition from MSBS to SIBS lines as the heater pump frequency approaches the gyroharmonic. Significantly far from the gyroharmonic, MSBS lines dominate, while close to the gyroharmonic, SIBS lines strengthen while MSBS lines weaken. New possibilities for diagnostic information are discussed in light of these new observations.

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

    Yashchuk, Vasil P.


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

  18. Investigation of mass reconstruction techniques for resonances in the scattering of $W^{\\pm}W^{\\pm} \\to W^{\\pm}W^{\\pm}$ at the LHC

    CERN Document Server

    Todt, Stefanie; Zuber, Kai

    Physics scenarios of electroweak symmetry breaking beyond the Standard Model introduce new resonances in the scattering of massive, weak gauge bosons. Due to the best signal to background ratio, the like-sign "W^{\\pm}W^{\\pm}"jj channel is the most favourable final state for a first glance at resonances in vector boson scattering (VBS) at a hadron collider such as the LHC. Resonances in this scattering process can be modelled with the approach of an effective field theory and the K-matrix unitarisation method. This thesis presents a study of mass reconstruction of resonances in the fully leptonic decay channel of like-sign "W^{\\pm}W^{\\pm}" scattering. Special emphasis lies on the technique of constrained minimisation leading to mass bound variables. For different resonance types, variables providing the best discovery potential in proton-proton collisions at a centre-of-mass energy of "\\unit[8]{TeV}" and an integrated luminosity of "\\unit[20]{fb^{-1}}" are determined and characterised.

  19. Fundamentals of neutron scattering by condensed matter

    Energy Technology Data Exchange (ETDEWEB)

    Scherm, R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)


    The purpose of this introductory lecture is to give the basic facts about the scattering of neutrons by condensed matter. This lecture is restricted to nuclear scattering, whereas magnetic scattering will be dealt with in an other course. Most of the formalism, however, can also be easily extended to magnetic scattering. (author) 17 figs., 3 tabs., 10 refs.

  20. The vibrational spectrum of solid ferrocene by inelastic neutron scattering

    NARCIS (Netherlands)

    Kemner, E.; De Schepper, I.M.; Kearley, G.J.; Jayasooriya, U.A.


    We calculate the spectrum of internal vibrations of a single ferrocene Fe(C5H5)2 molecule using ab initio density functional theory (without free parameters) and compare this with inelastic neutron scattering data on ferrocene in the solid state at 28 K. Due to the good agreement, we can assign each

  1. Measurement of the stimulated thermal Rayleigh scattering instability

    Energy Technology Data Exchange (ETDEWEB)

    Karr, T.J.; Rushford, M.C.; Murray, J.R.; Morris, J.R.


    Growth of perturbations due to stimulated thermal Rayleigh scattering was observed on a laser beam propagating in a 1 meter cell of CC14. Initial sinusoidal irradiance perturbations were seeded onto the laser leam, and their amplification in the cell was recorded by a near field camera. The perturbation growth rate is in agreement with analytical predictions of linearized propagation theory.

  2. Differential Cross Sections Of Electron Silver Scattering At Varying

    African Journals Online (AJOL)

    dimensional space, a central potential does not depend on the angular variable and . Therefore, in a scattering experiment it is easier to work in the Centre of mass frame, where a spherically symmetric potential has the form V(r) with = | ⃗|, due to the quantum mechanical uncertainty (i.e we can only predict the probability of ...

  3. The Controlling Parameters for EMIC Wave Scattering of Relativistic Electrons (United States)

    Zhang, X.; Li, W.; Ma, Q.; Thorne, R. M.; Angelopoulos, V.; Bortnik, J.


    Although there is growing support for relativistic electron losses due to precipitation from electromagnetic ion cyclotron (EMIC) wave scattering, this mechanism is yet to be quantified. Such a quantification has been difficult in the past, because equatorial electron measurements simultaneous with EMIC waves have been limited, due to the highly localized presence of EMIC waves in the magnetosphere. In this study, we examine parameters controlling characteristics of EMIC wave induced relativistic (0.3-6 MeV) electron scattering, directly based on simultaneous wave and particle measurements from Van Allen Probes. We first present a case study when relativistic electrons respond differently during two intervals of intense ( 1 nT) EMIC wave observations: one with no scattering signature and one with efficient electron losses at >1.8 MeV. Based on the observed EMIC wave spectra and background plasma conditions, we calculate the wave diffusion rates and model the evolution of electron pitch angle distributions. By comparing the modeled results with local observations of pitch angle distributions, we demonstrate that fpe/fce is critical in controlling the effectiveness of EMIC waves in scattering multi-MeV electrons. We then expand our analysis to explore the conditions (such as fpe/fce, wave frequency spectra, and ring current ion temperature and anisotropy levels) favorable for EMIC wave scattering multi-MeV electrons through multi-event analyses. Our study is important for accurately modeling relativistic electron loss processes in radiation belt electron forecasts.

  4. Sensitivity of a fibre scattered-light interferometer to external phase perturbations in an optical fibre

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A E; Potapov, V T [V.A.Kotel' nikov Institute of Radio Engineering and Electronics, Russian Academy of Sciences, Fryazino Branch, Fryazino, Moscow region (Russian Federation); Gorshkov, B G [OOO ' Petrofaiber' , Russia, Tula region, Novomoskovsk (Russian Federation)


    Sensitivity of a fibre scattered-light interferometer to external phase perturbations is studied for the first time. An expression is derived for an average power of a useful signal at the interferometer output under external harmonic perturbations in a signal fibre of the interferometer. It is shown that the maximum sensitivity of the scattered-light interferometer depends on the dispersion of the interferogram intensity. An average signal-to-noise ratio is determined theoretically and experimentally at the output of the interferometer at different amplitudes of external perturbations. Using the measured dependences of the signal-to-noise ratio, the threshold sensitivity of the fibre scattered-light interferometer to external phase perturbations is found. The results obtained can be used to optimise characteristics of optical time-domain reflectometers and to design individual phase-sensitive fibre-optic sensors. (laser applications and other topics in quantum electronics)

  5. High frequency and pulse scattering physical acoustics

    CERN Document Server

    Pierce, Allan D


    High Frequency and Pulse Scattering investigates high frequency and pulse scattering, with emphasis on the phenomenon of echoes from objects. Geometrical and catastrophe optics methods in scattering are discussed, along with the scattering of sound pulses and the ringing of target resonances. Caustics and associated diffraction catastrophes are also examined.Comprised of two chapters, this volume begins with a detailed account of geometrically based approximation methods in scattering theory, focusing on waves transmitted through fluid and elastic scatterers and glory scattering; surface ray r

  6. Extracting heterogeneous compliance of a single fracture from seismic scattering coupled with perturbation theory

    NARCIS (Netherlands)

    Minato, S.; Ghose, R.


    We have presented a new methodology to model the scattered wavefield due to a heterogeneous distribution of compliance along a single fracture and then to invert this compliance distribution or its power spectral density (PSD) from the scattered seismic response. We illustrate the validity through

  7. Estimating the location of a tunnel using correlation and inversion of Rayleigh wave scattering

    NARCIS (Netherlands)

    Kasililar, A.; Harmankaya, U.; Wapenaar, C.P.A.; Draganov, D.S.


    The investigation of near-surface scatterers, such as cavities, tunnels, abandoned mine shafts, and buried objects, is important to mitigate geohazards and environmental hazards. By inversion of travel times of cross-correlated scattered waves, due to the incident Rayleigh waves, we estimate the

  8. A rotational diffusion coefficient of the 70s ribosome determined by depolarized laser light scattering

    NARCIS (Netherlands)

    Bruining, J.; Fijnaut, H.M.

    We have obtained a rotational diffusion coefficient of the 70S ribosome isolated from Escherichia-coli (MRE-600), from the depolarized light scattering spectrum measured by photon correlation spectroscopy. The intensity correlation function of depolarized scattered light contains contributions due

  9. Method and apparatus for detecting and/or imaging clusters of small scattering centers in the body (United States)

    Perez-Mendez, V.; Sommer, F.G.


    An ultrasonic method and apparatus are provided for detecting and imaging clusters of small scattering centers in the breast wherein periodic pulses are applied to an ultrasound emitting transducer and projected into the body, thereafter being received by at least one receiving transducer positioned to receive scattering from the scattering center clusters. The signals are processed to provide an image showing cluster extent and location. 6 figs.

  10. Facile synthesis of terminal-alkyne bioorthogonal molecules for live -cell surface-enhanced Raman scattering imaging through Au-core and silver/dopamine-shell nanotags. (United States)

    Chen, Meng; Zhang, Ling; Yang, Bo; Gao, Mingxia; Zhang, Xiangmin


    Alkyne is unique, specific and biocompatible in the Raman-silent region of the cell, but there still remains a challenge to achieve ultrasensitive detection in living systems due to its weak Raman scattering. Herein, a terminal alkyne ((E)-2-[4-(ethynylbenzylidene)amino]ethane-1-thiol (EBAE)) with surface-enhanced Raman scattering is synthesized. The EBAE molecule possesses S- and C-termini, which can be directly bonded to gold nanoparticles and dopamine/silver by forming the Au-S chemical bond and the carbon-metal bond, respectively. The distance between Raman reporter and AuNPs/AgNPs can be reduced, contributing to forming hot-spot-based SERS substrate. The alkyne functionalized nanoparticles are based on Au core and encapsulating polydopamine shell, defined as Au-core and dopamine/Ag-shell (ACDS). The bimetallic ACDS induce strong SERS signals for molecular imaging that arise from the strong electromagnetic field. Furthermore, the EBAE provides a distinct peak in the cellular Raman-silent region with nearly zero background interference. The EBAE Raman signals could be tremendously enhanced when the Raman reporter is located at the middle of the Au-core and dopamine/Ag-shell. Therefore, this work could have huge potential benefits for the highly sensitive detection of intercellular information delivery by connecting the recognition molecules in biomedical diagnostics. Graphical abstract Terminal-alkyne-functionalized Au-core and silver/dopamine-shell nanotags for live-cell surface-enhanced Raman scattering imaging.

  11. Experimental and Computational Studies on the Scattering of an Edge-Guided Wave by a Hidden Crack on a Racecourse Shaped Hole

    Directory of Open Access Journals (Sweden)

    Benjamin Steven Vien


    Full Text Available Reliable and quantitative non-destructive evaluation for small fatigue cracks, in particular those in hard-to-inspect locations, is a challenging problem. Guided waves are advantageous for structural health monitoring due to their slow geometrical decay of amplitude with propagating distance, which is ideal for rapid wide-area inspection. This paper presents a 3D laser vibrometry experimental and finite element analysis of the interaction between an edge-guided wave and a small through-thickness hidden edge crack on a racecourse shaped hole that occurs, in practice, as a fuel vent hole. A piezoelectric transducer is bonded on the straight edge of the hole to generate the incident wave. The excitation signal consists of a 5.5 cycle Hann-windowed tone burst of centre frequency 220 kHz, which is below the cut-off frequency for the first order Lamb wave modes (SH1. Two-dimensional fast Fourier transformation (2D FFT is applied to the incident and scattered wave field along radial lines emanating from the crack mouth, so as to identify the wave modes and determine their angular variation and amplitude. It is shown experimentally and computationally that mid-plane symmetric edge waves can travel around the hole’s edge to detect a hidden crack. Furthermore, the scattered wave field due to a small crack length, a, (compared to the wavelength λ of the incident wave is shown to be equivalent to a point source consisting of a particular combination of body-force doublets. It is found that the amplitude of the scattered field increases quadratically as a function of a/λ, whereas the scattered wave pattern is independent of crack length for small cracks a << λ. This study of the forward scattering problem from a known crack size provides a useful guide for the inverse problem of hidden crack detection and sizing.

  12. Investigation of ionospheric D-region aeronomy using incoherent scatter radar and optical measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ying, W.P.


    The results of complementary radar and optical observations of the lower ionosphere are presented. These studies were accomplished using the facilities at the Arecibo Observatory in Puerto Rico, including 430-MHz incoherent scatter radar, tilting-filter photometers and 1-m Ebert-Fastie spectrometer. The incoherent-scatter radar consists of two operational modes, the total power and ion-line power-spectrum measurements. When combined together, atmospheric and ionospheric parameters are accessible, to varying degrees, as functions of time and height. These include electron concentration, ion-neutral collision frequency, neutral atmosphere temperature, pressure and wind, and mean negative positive ion masses and concentrations. This is made possible by techniques suggested in this thesis. These techniques are based on the concept of mapping between experimental and theoretical power spectra, combined with electron concentration information from total power measurement, to extract the underlying aeronomical parameters. The optical observation of the atmospheric nightglow complements the incapability of radar telemetry during nighttime due to decreased signal strength.

  13. Thermal neutron scattering evaluation framework (United States)

    Chapman, Chris; Leal, Luiz; Rahnema, Farzad; Danon, Yaron; Arbanas, Goran


    A neutron scattering kernel data evaluation framework for computation of model-dependent predictions and their uncertainties is outlined. In this framework, model parameters are fitted to double-differential cross section measurements and their uncertainties. For convenience, the initial implementation of this framework uses the molecular dynamics model implemented in the GROMACS code. It is applied to light water using the TIP4P/2005f interaction model. These trajectories computed by GROMACS are then processed using nMOLDYN to compute the density of states, which is then used to calculate the scattering kernel using the Gaussian approximation. Double differential cross sections computed from the scattering kernel are then fitted to double-differential scattering data measured at the Spallation Neutron Source detector at Oak Ridge National Laboratory. The fitting procedure is designed to yield optimized model-parameters and their uncertainties in the form of a covariance matrix, from which new evaluations of thermal neutron scattering kernel will be generated. The Unified Monte Carlo method will be used to fit the simulation data to the experimental data.

  14. An Approach to Extended Fresnel Scattering for Modeling of Depolarizing Soil-Trunk Double-Bounce Scattering

    Directory of Open Access Journals (Sweden)

    Thomas Jagdhuber


    Full Text Available Focusing on scattering from natural media, dihedral (double bounce scattering is often characterized as a soil-trunk double Fresnel reflection, like for instance, in most model-based decompositions. As soils are predominantly rough in agriculture, the classical Rank 1 dihedral scattering component has to be extended to account for soil roughness-induced depolarization. Therefore, an azimuthal Line of Sight (LoS rotation is applied solely on the soil plane of the double-bounce reflection to generate a depolarized dihedral scattering signal in agriculture. The results of the sensitivity analysis are shown for a distributed target in coherency matrix representation. It reveals that the combination of coherency matrix elements T22XD + T33XD is quasi-independent of the roughness-induced depolarization, while (T22XD − T33XD/(T22XD + T33XD is quasi-independent of the dielectric properties of the reflecting media. Therefore, a depolarization-independent retrieval of soil moisture or a direct roughness retrieval from the extended dihedral scattering component might be possible in stalk-dominated agriculture under certain conditions (e.g., the influence of a differential phase stays at a low level: ϕ < 15°. The first analyses with L-band airborne-SAR data of DLR’s E-SAR and F-SAR systems in agricultural regions during the AgriSAR, OPAQUE, SARTEO and TERENO project campaigns state the existence and potential of the extended Fresnel scattering mechanism to represent dihedral scattering between a rough (tilled soil and the stalks of the agricultural plants.

  15. Electromagnetic wave scattering from a forest or vegetation canopy - Ongoing research at the University of Texas at Arlington (United States)

    Karam, Mostafa A.; Amar, Faouzi; Fung, Adrian K.


    The Wave Scattering Research Center at the University of Texas at Arlington has developed a scattering model for forest or vegetation, based on the theory of electromagnetic-wave scattering in random media. The model generalizes the assumptions imposed by earlier models, and compares well with measurements from several forest canopies. This paper gives a description of the model. It also indicates how the model elements are integrated to obtain the scattering characteristics of different forest canopies. The scattering characteristics may be displayed in the form of polarimetric signatures, represented by like- and cross-polarized scattering coefficients, for an elliptically-polarized wave, or in the form of signal-distribution curves. Results illustrating both types of scattering characteristics are given.

  16. Acoustic signal propagation characterization of conduit networks (United States)

    Khan, Muhammad Safeer

    may be intractable. A tractable approach is to develop an empirical model of the attenuation that has a stochastic component of a finite mean and variance to account for the random variable error akin to addition of a normally distributed random variable shadowing component in the path loss models of radio frequency (RF) wireless communication channels. This approach forms the crux of the present study. To develop an empirical model, a large number of measurements in conduit networks were made in the field and in a laboratory test set up to measure the variability of attenuation with variation in four parameters. These parameters include distance of the receiver from the source, frequency, numbers and lengths of side branches. Variation in signal attenuation with distance at each transmitted frequency is predicted by using linear regression through the scatter plot of the measured data. Variations in signal attenuation due to change in frequency, number and lengths of side branches are measured in the field and laboratory tests by comparing the reference transmitted pressure with the received pressure at either the open end or at some distance away from the source along the conduit length. Residuals between measured and predicted sound pressure levels are computed and tested for normal probability distribution through a graphical method as well as a statistical goodness of fit test for quantifiable results. The findings indicate that an empirical model of signal attenuation, which includes a normally distributed random variable component to account for random variable errors in the attenuation measurements, gives a more accurate prediction of received acoustic signal strength in a conduit compared to existing theoretical models.

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

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


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

  18. Proton-Nucleus Scattering Approximations and Implications for LHC Crystal Collimation

    Energy Technology Data Exchange (ETDEWEB)

    Noble, Robert; /SLAC


    In particle accelerators, scattered protons with energies close to the incident particles may travel considerable distances with the beam before impacting on accelerator components downstream. To analyze such problems, angular deflection and energy loss of scattered particles are the main quantities to be simulated since these lead to changes in the beam's phase space distribution and particle loss. Simple approximations for nuclear scattering processes causing limited energy loss to high-energy protons traversing matter are developed which are suitable for rapid estimates and reduced-description Monte Carlo simulations. The implications for proton loss in the Large Hadron Collider due to nuclear scattering on collimation crystals are discussed.

  19. Surface-Enhanced Raman Scattering Physics and Applications

    CERN Document Server

    Kneipp, Katrin; Kneipp, Harald


    Almost 30 years after the first reports on surface-enhanced Raman signals, the phenomenon of surface-enhanced Raman scattering (SERS) is now well established. Yet, explaining the enhancement of a spectroscopic signal by fouteen orders of magnitude continues to attract the attention of physicists and chemists alike. And, at the same time and rapidly growing, SERS is becoming a very useful spectroscopic tool with exciting applications in many fields. SERS gained particular interest after single-molecule Raman spectroscopy had been demonstrated. This bookl summarizes and discusses present theoretical approaches that explain the phenomenon of SERS and reports on new and exciting experiments and applications of the fascinating spectroscopic effect.

  20. Luminosity calibration from elastic scattering

    CERN Document Server

    Stenzel, H


    The absolute luminosity of the LHC at the ATLAS interaction point will be calibrated by the measurement of the t-distribution of elastic pp-scattering in the Coulomb-Nuclear interference region. The ALFA detector housed in Roman Pots located 240m away from IP1 is designed to approach the beam at mm distance and to measure elastic pp-scattering at micro-radian scattering angles. This measurement will be performed with dedicated runs using a special beam optics with high beta* and parallel-to-point focusing in order to access the Coulomb regime. In this note the expected performance of this method, evaluated with a simulation of the experimental set-up, is presented.

  1. Quantifying entanglement with scattering experiments (United States)

    Marty, O.; Epping, M.; Kampermann, H.; Bruß, D.; Plenio, M. B.; Cramer, M.


    We show how the entanglement contained in states of spins arranged on a lattice may be lower bounded with observables arising in scattering experiments. We focus on the partial differential cross section obtained in neutron scattering from magnetic materials but our results are sufficiently general such that they may also be applied to, e.g., optical Bragg scattering from ultracold atoms in optical lattices or from ion chains. We discuss resonating valence bond states and ground and thermal states of experimentally relevant models—such as the Heisenberg, Majumdar-Ghosh, and XY models—in different geometries and with different spin numbers. As a by-product, we find that for the one-dimensional XY model in a transverse field such measurements reveal factorization and the quantum phase transition at zero temperature.

  2. Helium atom scattering from surfaces

    CERN Document Server


    High resolution helium atom scattering can be applied to study a number of interesting properties of solid surfaces with great sensitivity and accuracy. This book treats in detail experimental and theoretical aspects ofthis method as well as all current applications in surface science. The individual chapters - all written by experts in the field - are devoted to the investigation of surface structure, defect shapes and concentrations, the interaction potential, collective and localized surface vibrations at low energies, phase transitions and surface diffusion. Over the past decade helium atom scattering has gained widespread recognitionwithin the surface science community. Points in its favour are comprehensiveunderstanding of the scattering theory and the availability of well-tested approximation to the rigorous theory. This book will be invaluable to surface scientists wishing to make an informed judgement on the actual and potential capabilities of this technique and its results.


    Directory of Open Access Journals (Sweden)



    Full Text Available Here, of great interest to us is a quantitative study of the scattering properties from ramified polymeric systems of arbitrary topology. We consider three types of systems, namely ramified polymers in solution, ramified polymer blends, or ternary mixtures made of two ramified polymers of different chemical nature immersed in a good solvent. To achieve the goal of the study, use is made of the Random Phase Approximation. First we determine the exact expression of the form factor of an ideal ramified polymer of any topology, from which we extract the exact expression of its gyration radius. Using the classical Zimm's formulae and the exact form factor, we determine all scattering properties of these three types of ramified polymeric systems. The main conclusion is that ramification of the chains induces drastic changes of the scattering properties.

  4. Scattering functions of Platonic solids

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xin [Rensselaer Polytechnic Institute; Shew, Chwen-Yang [City University of New York (CUNY); He, Lilin [ORNL; Meilleur, Flora [ORNL; Myles, Dean A A [ORNL; Liu, Emily [Rensselaer Polytechnic Institute; Zhang, Yang [ORNL; Smith, Greg [ORNL; Herwig, Kenneth W [ORNL; Pynn, Roger [ORNL; Chen, Wei-Ren [ORNL


    The single-particle small-angle scattering properties of five Platonic solids, including the tetrahedron, hexahedron, octahedron, dodecahedron and icosahedron, are systematically investigated. For each given geometry, the Debye spatial autocorrelation function, pair distance distribution function and intraparticle structure factor (form factor) are calculated and compared with the corresponding scattering function of a spherical reference system. From the theoretical models, the empirical relationship between the dodecahedral and icosahedral structural characteristics and those of the equivalent spheres is found. Moreover, the single-particle scattering properties of icosahedral and spherical shells with identical volume are investigated, and the prospect of using different data analysis approaches to explore their structural differences is presented and discussed.

  5. Scattering functions of Platonic solids

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei-Ren [ORNL; Herwig, Kenneth W [ORNL; Li, Xin [ORNL; Liu, Emily [Rensselaer Polytechnic Institute (RPI); Pynn, Roger [ORNL; Shew, Chwen-Yang [City University of New York (CUNY); Smith, Gregory Scott [ORNL; Myles, Dean A A [ORNL; He, Lilin [ORNL; Meilleur, Flora [ORNL


    In this report the single-particle scattering properties of five Platonic solids, including tetrahedron, hexahedron, octahedron, dodecahedron and icosahedron, are investigated in a systematic manner. For each given geometry, the Debye spatial autocorrelation function (r), pair distance distribution function (PDDF) p (r) and intraparticle structure factor (form factor) P (Q) are respectively calculated and compared to the corresponding scattering function of the spherical referential system. Based on our theoretical models, the empirical relationship between the dodecahedral and icosahedral structural characteristics and those of the equivalent spheres is found. Moreover, the single-particle scattering properties of the icosahedral and the spherical shells with the same volume are further investigated and the prospect of using different data analysis approaches to explore their structural difference is also presented and discussed.

  6. Pipe wall damage detection by electromagnetic acoustic transducer generated guided waves in absence of defect signals. (United States)

    Vasiljevic, Milos; Kundu, Tribikram; Grill, Wolfgang; Twerdowski, Evgeny


    Most investigators emphasize the importance of detecting the reflected signal from the defect to determine if the pipe wall has any damage and to predict the damage location. However, often the small signal from the defect is hidden behind the other arriving wave modes and signal noise. To overcome the difficulties associated with the identification of the small defect signal in the time history plots, in this paper the time history is analyzed well after the arrival of the first defect signal, and after different wave modes have propagated multiple times through the pipe. It is shown that the defective pipe can be clearly identified by analyzing these late arriving diffuse ultrasonic signals. Multiple reflections and scattering of the propagating wave modes by the defect and pipe ends do not hamper the defect detection capability; on the contrary, it apparently stabilizes the signal and makes it easier to distinguish the defective pipe from the defect-free pipe. This paper also highlights difficulties associated with the interpretation of the recorded time histories due to mode conversion by the defect. The design of electro-magnetic acoustic transducers used to generate and receive the guided waves in the pipe is briefly described in the paper.

  7. Ultra-sensitive molecular detection using surface-enhanced Raman scattering on periodic metal-dielectric nanostructures (United States)

    Nien, Chun; Li, Yi-Hsuan; Su, Vin-Cent; Kuan, Chieh-Hsiung


    Surface-enhanced Raman scattering (SERS) is a powerful technique for trace chemical analysis and single molecule detection in the application of biochemical monitoring and food safety due to its ability to enhance the Raman scattering of molecules near the metallic surface or nanostructures. Here, we present a comprehensive study of the SERS enhancement by the periodically nanostructured surface, where the thin film of silver is deposited onto the surface, except the sidewall of posts, of 1-D lamellar gratings with varying pitch to forming metal-dielectric composite nanostructures. By enhancing the localized and surface-propagating mode in the vicinity of the concaves, the SERS signal can be improved by amplifying the intensity of electric field and increasing the optical path length of the incident light. Experimental investigations show that the enhancement factor can be manipulated by varying the polarization of incident light and the pitch size of gratings. To demonstrate the SERS effects of the proposed structures, thin layers of benzoic acid, which is commonly used as a food preservative, are deposited on the SERS substrates by spin-coating a solution of benzoic acid and dried at room temperature. A Confocal Raman microscope with a 532 nm laser source is used to illuminate light and measure the Raman spectrum of benzoic acid. We demonstrate the Raman signal of benzoic acid can be enhanced on the order of 102 on the SERS substrates.

  8. Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

    Directory of Open Access Journals (Sweden)

    S. Schweitzer


    Full Text Available LEO-LEO infrared-laser occultation (LIO is a new occultation technique between Low Earth Orbit (LEO satellites, which applies signals in the short wave infrared spectral range (SWIR within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We

  9. Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites (United States)

    Schweitzer, S.; Kirchengast, G.; Proschek, V.


    LEO-LEO infrared-laser occultation (LIO) is a new occultation technique between Low Earth Orbit (LEO) satellites, which applies signals in the short wave infrared spectral range (SWIR) within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO) method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity) and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms) of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We conclude that

  10. Scatter correction for large non-human primate brain imaging using microPET

    Energy Technology Data Exchange (ETDEWEB)

    Naidoo-Variawa, S; Lehnert, W; Banati, R B; Meikle, S R, E-mail: [Discipline of Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, PO Box 170, Lidcombe, NSW 1825, Sydney (Australia)


    The baboon is well suited to pre-clinical evaluation of novel radioligands for positron emission tomography (PET). We have previously demonstrated the feasibility of using a high resolution animal PET scanner for this application in the baboon brain. However, the non-homogenous distribution of tissue density within the head may give rise to photon scattering effects that reduce contrast and compromise quantitative accuracy. In this study, we investigated the magnitude and distribution of scatter contributing to the final reconstructed image and its variability throughout the baboon brain using phantoms and Monte Carlo simulated data. The scatter fraction is measured up to 36% at the centre of the brain for a wide energy window (350-650 keV) and 19% for a narrow (450-650 keV) window. We observed less than 3% variation in the scatter fraction throughout the brain and found that scattered events arising from radioactivity outside the field of view contribute less than 1% of measured coincidences. In a contrast phantom, scatter and attenuation correction improved contrast recovery compared with attenuation correction on its own and reduced bias to less than 10% at the expense of the reduced signal-to-noise ratio. We conclude that scatter correction is a necessary step for ensuring high quality measurements of the radiotracer distribution in the baboon brain with a microPET scanner, while it is not necessary to model out of field of view scatter or a spatially variant scatter function.

  11. Quantum Interference and Entanglement Induced by Multiple Scattering of Light

    DEFF Research Database (Denmark)

    Ott, Johan Raunkjær; Mortensen, Asger; Lodahl, Peter


    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...... results suggest that multiple scattering provides a promising way of coherently interfering many independent quantum states of light of potential use in quantum information processing....

  12. On the coherent scattering length of natural gadolinium

    CERN Document Server

    Frank, A I; Kulin, G V; Kulina, O V


    Using the reflection of thermal neutrons from the surface of plane sample the coherent scattering length of natural gadolinium was measured. Due to the closeness of resonances in radiation capture cross section the imaginary part of coherent scattering length strongly depends on neutron wavelength. Its real part can be expressed as a sum of Re(b)=b sub 0 + b(lambda). For the constant component of the real part we experimentally obtained the value b sub 0 =(11.5+-0.7)Fm. This result should be considered as a preliminary.

  13. Optical Waveguide Scattering Reduction. II. (United States)


    straightforward (23)application of Fraunhofer diffraction theory: ik(z 4-a/2) . 1/2 A(y,z) = A oe 0 2ik an [ix(z-z 0)Io , 0 0 a/2 eikr f e iky ’ ,dy. (45) -a12 The...scattering analysis in the Rayleigh-Debye limit. 45 17 Definition of parameters for determining the scattered field in the Fraunhofer zone...They present photo- graphs showing lO-pm sized triangular and hexagonal inclusions which they describe as metal particles from the crucible. We have not

  14. Spectroscopic study of light scattering in linear alkylbenzene for liquid scintillator neutrino detectors

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiang, E-mail: [Hubei Nuclear Solid Physics Key Laboratory, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, 430072, Wuhan (China); Liu, Qian, E-mail: [School of Physics, University of Chinese Academy of Sciences, 100049, Beijing (China); Han, Junbo [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, 430074, Wuhan (China); Zhang, Zhenyu [Hubei Nuclear Solid Physics Key Laboratory, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, 430072, Wuhan (China); Zhang, Xuan; Ding, Yayun [Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing (China); Zheng, Yangheng [School of Physics, University of Chinese Academy of Sciences, 100049, Beijing (China); Zhou, Li; Cao, Jun; Wang, Yifang [Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing (China)


    We have set up a light scattering spectrometer to study the depolarization of light scattering in linear alkylbenzene. The scattering spectra show that the depolarized part of light scattering is due to Rayleigh scattering. The additional depolarized Rayleigh scattering can make the effective transparency of linear alkylbenzene much better than expected. Therefore, sufficient scintillation photons can transmit through large liquid scintillator detector, such as that of the JUNO experiment. Our study is crucial to achieving an unprecedented energy resolution of 3 %/√(E(MeV)) required for the JUNO experiment to determine the neutrino mass hierarchy. The spectroscopic method can also be used to examine the depolarization of other organic solvents used in neutrino experiments.

  15. Intrinsic and scattering attenuation of the Mt Fuji Region, Japan (United States)

    Chung, Tae Woong; Lees, Jonathan M.; Yoshimoto, Kazuo; Fujita, Eisuke; Ukawa, Motoo


    Mount Fuji is the focus of intense study because of its potential hazard signaled by seismic, geologic and historical activity. Based on extensive seismic data recorded in the vicinity of Mt Fuji, coda quality factor (Q-1C) using a single scattering model hypothesis, and intrinsic and scattering quality factor (Q-1i and Q-1S) using the Multiple Lapse Time Window (MLTW) method were measured. To focus the study on the magmatic structure below Mt Fuji, the data were separated into two groups: a near-Fuji region of rays traversing an area with radius 5 km around the summit (R 20 km). This classification shows the largest discrepancy of Q-1C at a range of sampling volumes corresponding to overlapped sampling depth of about 80 km. Further, the spatial division shows significant difference of Q-1i and Q-1s at hypocentral distance of 80 km. The large difference of Q-1s in bandwidths 2-4, and 4-8 Hz indicates lithospheric heterogeneity beneath Mt Fuji with a characteristic heterogeneity scale length of about 1 km. The results have a small error range due to the large data sample, showing that all Q-1 values in the near-Fuji area are greater than those of the far-Fuji area, and Q-1i for both the near and far-Fuji areas is higher than Q-1s at high frequencies. The Q-1i and Q-1s values for far-Fuji are in the range of values for typical non-volcanic areas. The Q-1i values of the near-Fuji area are lower than those of other volcanic areas considered, where as values of Q-1s are not. The low Q-1i for the volcanic region of near-Fuji suggests that the magmatic activity, indicated by percent partial melt, in the vicinity of Mt Fuji is not as active as hot spot volcanoes, such as Kilauea, Hawaii.

  16. Death due to asthma

    Directory of Open Access Journals (Sweden)

    Albert L. Sheffer


    Full Text Available The prevalence and fatality rate of asthma have increased worldwide. Underdiagnosis and undertreatment of asthma are central to the occurrence of fatal asthma. Atopy is the principal risk factor associated with asthma. However, consideration of the epidemiologic, physiologic, pharmacologic, pathologic and clinical parameters of asthma assessment may provide valuable insight into death due to asthma. Psychologic and socioeconomic factors may further aggravate the asthma status. Ethnic minorities are at increased risk of asthma. The perception of dyspnea may be blunted in asthma sufferers. Slow-onset fatal asthma may be associated with submucosal eosinophilic, whereas sudden-onset may be associated with submucosal neutrophilia. Fatal asthma occurs in patients abusing regular |32-agonist therapy. Peak flow assessment often provides insight into asthma deterioration prior to signs of respiratory distress. Markers of risk of death due to asthma further identify the fatality-prone asthma patient.

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

    Turner, J E; Hamm, R N


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

  18. Inelastic Scattering in STEM for Studying Structural and Electronic Properties of Chalcogenide-Based Semiconductor Nanocrystals (United States)

    Gunawan, Aloysius Andhika

    Transmission electron microscopy (TEM) relies upon elastic and inelastic scattering signals to perform imaging and analysis of materials. TEM images typically contain contributions from both types of scattering. The ability to separate the contributions from elastic and inelastic processes individually through energy filter or electron energy loss spectroscopy (EELS) allows unique analysis that is otherwise unachievable. Two prominent types of inelastic scattering probed by EELS, namely plasmon and core-loss excitations, are useful for elucidating structural and electronic properties of chalcogenide-based semiconductor nanocrystals. The elastic scattering, however, is still a critical part of the analysis and used in conjunction with the separated inelastic scattering signals. The capability of TEM operated in scanning mode (STEM) to perform localized atomic length scale analysis also permits the understanding of the nanocrystals unattainable by other techniques. Despite the pivotal role of inelastic scatterings, their contributions for STEM imaging, particularly high-angle annular dark field STEM (HAADF-STEM), are not completely understood. This is not surprising since it is currently impossible to experimentally separate the inelastic signals contributing to HAADF-STEM images although images obtained under bright-field TEM mode can be analyzed separately from their scattering contributions using energy-filtering devices. In order to circumvent such problem, analysis based on simulation was done. The existing TEM image simulation algorithm called Multislice method, however, only accounts for elastic scattering. The existing Multislice algorithm was modified to incorporate (bulk or volume) plasmon inelastic scattering. The results were verified based on data from convergent-beam electron diffraction (CBED), electron energy loss spectroscopy (EELS), and HAADF-STEM imaging as well as comparison to experimental data. Dopant atoms are crucial factors which control

  19. Death due to asthma


    Sheffer, Albert L.


    The prevalence and fatality rate of asthma have increased worldwide. Underdiagnosis and undertreatment of asthma are central to the occurrence of fatal asthma. Atopy is the principal risk factor associated with asthma. However, consideration of the epidemiologic, physiologic, pharmacologic, pathologic and clinical parameters of asthma assessment may provide valuable insight into death due to asthma. Psychologic and socioeconomic factors may further aggravate the asthma status. Ethnic minoriti...

  20. Human due diligence. (United States)

    Harding, David; Rouse, Ted


    Most companies do a thorough job of financial due diligence when they acquire other companies. But all too often, deal makers simply ignore or underestimate the significance of people issues in mergers and acquisitions. The consequences are severe. Most obviously, there's a high degree of talent loss after a deal's announcement. To make matters worse, differences in decision-making styles lead to infighting; integration stalls; and productivity declines. The good news is that human due diligence can help companies avoid these problems. Done early enough, it helps acquirers decide whether to embrace or kill a deal and determine the price they are willing to pay. It also lays the groundwork for smooth integration. When acquirers have done their homework, they can uncover capability gaps, points of friction, and differences in decision making. Even more important, they can make the critical "people" decisions-who stays, who goes, who runs the combined business, what to do with the rank and file-at the time the deal is announced or shortly thereafter. Making such decisions within the first 30 days is critical to the success of a deal. Hostile situations clearly make things more difficult, but companies can and must still do a certain amount of human due diligence to reduce the inevitable fallout from the acquisition process and smooth the integration. This article details the steps involved in conducting human due diligence. The approach is structured around answering five basic questions: Who is the cultural acquirer? What kind of organization do you want? Will the two cultures mesh? Who are the people you most want to retain? And how will rank-and-file employees react to the deal? Unless an acquiring company has answered these questions to its satisfaction, the acquisition it is making will be very likely to end badly.

  1. Consistent Signal Reconstruction and Convex Coding


    Moonen, Marc; De Moor, Bart; Thao, Nguyen Truong; Vetterli, Martin


    The field of signal processing has known tremendous progress with the development of digital signal processing. The first foundation of digital signal processing is due to Shannon's sampling theorem which shows that any bandlimited analog signal can...

  2. Pathlength Determination for Gas in Scattering Media Absorption Spectroscopy (United States)

    Mei, Liang; Somesfalean, Gabriel; Svanberg, Sune


    Gas in scattering media absorption spectroscopy (GASMAS) has been extensively studied and applied during recent years in, e.g., food packaging, human sinus monitoring, gas diffusion studies, and pharmaceutical tablet characterization. The focus has been on the evaluation of the gas absorption pathlength in porous media, which a priori is unknown due to heavy light scattering. In this paper, three different approaches are summarized. One possibility is to simultaneously monitor another gas with known concentration (e.g., water vapor), the pathlength of which can then be obtained and used for the target gas (e.g., oxygen) to retrieve its concentration. The second approach is to measure the mean optical pathlength or physical pathlength with other methods, including time-of-flight spectroscopy, frequency-modulated light scattering interferometry and the frequency domain photon migration method. By utilizing these methods, an average concentration can be obtained and the porosities of the material are studied. The last method retrieves the gas concentration without knowing its pathlength by analyzing the gas absorption line shape, which depends upon the concentration of buffer gases due to intermolecular collisions. The pathlength enhancement effect due to multiple scattering enables also the use of porous media as multipass gas cells for trace gas monitoring. All these efforts open up a multitude of different applications for the GASMAS technique. PMID:24573311

  3. Pathlength Determination for Gas in Scattering Media Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Liang Mei


    Full Text Available Gas in scattering media absorption spectroscopy (GASMAS has been extensively studied and applied during recent years in, e.g., food packaging, human sinus monitoring, gas diffusion studies, and pharmaceutical tablet characterization. The focus has been on the evaluation of the gas absorption pathlength in porous media, which a priori is unknown due to heavy light scattering. In this paper, three different approaches are summarized. One possibility is to simultaneously monitor another gas with known concentration (e.g., water vapor, the pathlength of which can then be obtained and used for the target gas (e.g., oxygen to retrieve its concentration. The second approach is to measure the mean optical pathlength or physical pathlength with other methods, including time-of-flight spectroscopy, frequency-modulated light scattering interferometry and the frequency domain photon migration method. By utilizing these methods, an average concentration can be obtained and the porosities of the material are studied. The last method retrieves the gas concentration without knowing its pathlength by analyzing the gas absorption line shape, which depends upon the concentration of buffer gases due to intermolecular collisions. The pathlength enhancement effect due to multiple scattering enables also the use of porous media as multipass gas cells for trace gas monitoring. All these efforts open up a multitude of different applications for the GASMAS technique.

  4. Concurrent determination of nanocrystal shape and amorphous phases in complex materials by diffraction scattering computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Birkbak, Mie Elholm; Nielsen, Ida Gjerlevsen; Frølich, Simon; Stock, Stuart R.; Kenesei, Peter; Almer, Jonathan D.; Birkedal, Henrik


    Advanced functional materials often contain multiple phases which are (nano)crystalline and/or amorphous. The spatial distribution of these phases and their properties, including nanocrystallite size and shape, often drives material function yet is difficult to obtain with current experimental techniques. This article describes the use of diffraction scattering computed tomography, which maps wide-angle scattering information onto sample space, to address this challenge. The wide-angle scattering signal contains information on both (nano)crystalline and amorphous phases. Rietveld refinement of reconstructed diffraction patterns is employed to determine anisotropic nanocrystal shapes. The background signal from refinements is used to identify contributing amorphous phases through multivariate curve resolution. Thus it is demonstrated that reciprocal space analysis in combination with diffraction scattering computed tomography is a very powerful tool for the complete analysis of complex multiphase materials such as energy devices.

  5. Physics Model Based Scatter Correction in Multi-source Interior Computed Tomography. (United States)

    Gong, Hao; Li, Bin; Jia, Xun; Gao, Guohua


    Multi-source interior computed tomography (CT) has a great potential to provide ultra-fast and organ-oriented imaging at low radiation dose. However, X-ray cross scattering from multiple simultaneously activated X-ray imaging chains compromises imaging quality. Previously, we published two hardware based scatter correction methods for multi-source interior CT. Here, we propose a software based scatter correction method, with the benefit of no need for hardware modifications. The new method is based on a physics model and an iterative framework. The physics model was derived analytically, and was used to calculate X-ray scattering signals in both forward direction and cross directions in multi-source interior CT. The physics model was integrated to an iterative scatter correction framework to reduce scatter artifacts. The method was applied to phantom data from both Monte Carlo simulations and physical experimentation that were designed to emulate the image acquisition in a multi-source interior CT architecture recently proposed by our team. The proposed scatter correction method reduced scatter artifacts significantly, even with only one iteration. Within a few iterations, the reconstructed images fast converged toward the "scatter-free" reference images. After applying the scatter correction method, the maximum CT number error at the region-of-interests (ROIs) was reduced to 46 HU in numerical phantom dataset and 48 HU in physical phantom dataset respectively, and the contrast-noise-ratio (CNR) at those ROIs increased by up to 44.3% and up to 19.7% respectively. The proposed physics model based iterative scatter correction method could be useful for scatter correction in dual-source or multi-source CT.

  6. Optimal and adaptive methods of processing hydroacoustic signals (review) (United States)

    Malyshkin, G. S.; Sidel'nikov, G. B.


    Different methods of optimal and adaptive processing of hydroacoustic signals for multipath propagation and scattering are considered. Advantages and drawbacks of the classical adaptive (Capon, MUSIC, and Johnson) algorithms and "fast" projection algorithms are analyzed for the case of multipath propagation and scattering of strong signals. The classical optimal approaches to detecting multipath signals are presented. A mechanism of controlled normalization of strong signals is proposed to automatically detect weak signals. The results of simulating the operation of different detection algorithms for a linear equidistant array under multipath propagation and scattering are presented. An automatic detector is analyzed, which is based on classical or fast projection algorithms, which estimates the background proceeding from median filtering or the method of bilateral spatial contrast.

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

    DEFF Research Database (Denmark)

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


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

  8. Reactor Antineutrino Signals at Morton and Boulby

    CERN Document Server

    Dye, Steve


    Increasing the distance from which an antineutrino detector is capable of monitoring the operation of a registered reactor, or discovering a clandestine reactor, strengthens the Non-Proliferation of Nuclear Weapons Treaty. This report presents calculations of reactor antineutrino interactions, from quasi-elastic neutrino-proton scattering and elastic neutrino-electron scattering, in a water-based detector operated >10 km from a commercial power reactor. It separately calculates signal from the proximal reactor and background from all other registered reactors. The main results are interaction rates and kinetic energy distributions of charged leptons scattered from quasi-elastic and elastic processes. Comparing signal and background distributions evaluates reactor monitoring capability. Scaling the results to detectors of different sizes, target media, and standoff distances is straightforward. Calculations are for two examples of a commercial reactor (P_th~3 GW) operating nearby (L~20 km) an underground facil...

  9. Direction of Arrival Estimation in the presence of Scatterer in noisy environment

    Directory of Open Access Journals (Sweden)

    T. Aslam


    Full Text Available We present an algorithm to estimate direction of arrival (DOA of an incoming wave received at an array antenna in the scenario where the incoming wave is contaminated by the additive white Gaussian noise and scattered by arbitrary shaped 3D scatterer(s. We present different simulation examples to show the validity of the proposed method. It is observed that the proposed algorithm is capable of closely estimating the DOA of an incoming wave irrespective of the shape of the scatterer provided the decision is made over multiple iterations. Moreover, presence of noise affects the estimate especially in the case of low signal-to-noise ratio (SNR that gives a relatively large estimation error. However, for larger SNR the DOA estimation is primarily dependent on the scatterer only.

  10. Measurement of very small hydrogen content in zirconium alloys by measuring thermal neutron incoherent scattering

    CERN Document Server

    Choi, Y N; Lee, C H; Oh, H S; Park, S D; Somenkov, V A


    In neutron-scattering experiments, the incoherent scattering contributes to the background signal, which is an unwelcome property of matter. Among natural nuclei, the hydrogen nucleus (proton) has a remarkably large value of incoherent neutron scattering cross section. Therefore, a very small amount of hydrogen in a material could be analyzed by measuring the neutron incoherent scattering of the material. The hydrogen content of a metal or semiconductor is a matter of concern because it can affect significantly the physical, mechanical or chemical properties of materials although the amount of hydrogen is very small. In this study, the neutron incoherent scattering was measured using a 1-D position-sensitive detector at 1.835 A. Estimated detection limits are about 5 and 2 mu g/g for 10-min and 1-h measurements, respectively. Using the calibration data obtained by measurement of artificial samples (zircaloy+polypropylene films), the relative amounts of hydrogen in three commercial zircaloy samples were estima...

  11. Experimental demonstration of singular-optical colouring of regularly scattered white light

    DEFF Research Database (Denmark)

    Angelsky, O.V.; Hanson, Steen Grüner; Maksimyak, P.P.


    Experimental interference modelling of the effects of colouring of a beam traversing a light-scattering medium is presented. It is shown that the result of colouring of the beam at the output of the medium depends on the magnitudes of the phase delays of the singly forward scattered partial signals....... The colouring mechanism has for the first time experimentally been illustrated for a forward propagating beam through a light-scattering medium. This is showed in video-fragments of the interferograms recorded within the zero interference fringe with a gradual change of the path difference of the interfering...... polychromatic wave trains. Spectral investigation of the effects of colouring has been carried out using a solution of liquid crystal in a polymer matrix. The amplitude ratio of the non-scattered and the singly forward scattered interfering components significantly affects the colour intensity. It has further...

  12. Forward modeling of an atmospheric scenario: path characterization in terms of scattering intensity

    Energy Technology Data Exchange (ETDEWEB)

    Bosisio, Ada Vittoria; Cadeddu, Maria P.; Fionda, Ermanno; Ciotti, Piero


    The knowledge of possible impairments due to atmospheric propagation is of importance in the framework of future 5G mobile networks that use spectrum resource up to the W band. Here, the authors propose the scalar Scatter Indicator (SI), defined as the difference between the simulated TB at 72 GHz and the TB value at the same frequency estimated from a combination of TBs values at 23.8 and 31.4 GHz under assumed scatter-free condition. On the basis of radiosonde profiles observed in Milan, Linate (Italy) in 2005, clear-sky scenarios are used as reference to define a scatter-free TB’s database. A second database of simulated TBs including scattering effects is generated with ARTS to build the SI. Numerical results show that the SI assumes significant positive values with increasing drop effective radius and total liquid water LWP and it can be used to identify the scattering due to hydrometeor

  13. Linearized least-square imaging of internally scattered data

    KAUST Repository

    Aldawood, Ali


    Internal multiples deteriorate the quality of the migrated image obtained conventionally by imaging single scattering energy. However, imaging internal multiples properly has the potential to enhance the migrated image because they illuminate zones in the subsurface that are poorly illuminated by single-scattering energy such as nearly vertical faults. Standard migration of these multiples provide subsurface reflectivity distributions with low spatial resolution and migration artifacts due to the limited recording aperture, coarse sources and receivers sampling, and the band-limited nature of the source wavelet. Hence, we apply a linearized least-square inversion scheme to mitigate the effect of the migration artifacts, enhance the spatial resolution, and provide more accurate amplitude information when imaging internal multiples. Application to synthetic data demonstrated the effectiveness of the proposed inversion in imaging a reflector that is poorly illuminated by single-scattering energy. The least-square inversion of doublescattered data helped delineate that reflector with minimal acquisition fingerprint.

  14. Vortex scattering and intercommuting cosmic strings on a noncommutative spacetime (United States)

    Joseph, Anosh; Trodden, Mark


    We study the scattering of noncommutative vortices, based on the noncommutative field theory developed in [A. P. Balachandran, T. R. Govindarajan, G. Mangano, A. Pinzul, B. A. Qureshi, and S. Vaidya, Phys. Rev. DPRVDAQ1550-7998 75, 045009 (2007).10.1103/PhysRevD.75.045009], as a way to understand the interaction of cosmic strings. In the center-of-mass frame, the effects of noncommutativity vanish, and therefore the reconnection of cosmic strings occurs in an identical manner to the commutative case. However, when scattering occurs in a frame other than the center-of-mass frame, strings still reconnect but the well-known 90° scattering no longer need correspond to the head-on collision of the strings, due to the breakdown of Lorentz invariance in the underlying noncommutative field theory.

  15. Spectral bandwidth reduction of Thomson scattered light by pulse chirping

    Directory of Open Access Journals (Sweden)

    Isaac Ghebregziabher


    Full Text Available Based on single particle tracking in the framework of classical Thomson scattering with incoherent superposition, we developed a relativistic, three-dimensional numerical model that calculates and quantifies the characteristics of emitted radiation when a relativistic electron beam interacts with an intense laser pulse. This model has been benchmarked against analytical expressions, based on the plane wave approximation to the laser field, derived by Esarey et al. [Phys. Rev. E 48, 3003 (1993PLEEE81063-651X10.1103/PhysRevE.48.3003]. For laser pulses of sufficient duration, we find that the scattered radiation spectrum is broadened due to interferences arising from the pulsed nature of the laser. We find that by appropriately chirping the scattering laser pulse, spectral broadening can be minimized, and the peak on-axis brightness of the emitted radiation is increased by a factor of approximately 5.

  16. Optical scattering in glass ceramics

    NARCIS (Netherlands)

    Mattarelli, M.; Montagna, M.; Verrocchio, P.


    The transparency of glass ceramics with nanocrystals is generally higher than that expected from the theory of Rayleigh scattering. We attribute this ultra-transparency to the spatial correlation of the nanoparticles. The structure factor is calculated for a simple model system, the random

  17. Nuclear matter and electron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sick, I. [Dept. fuer Physik und Astronomie, Univ. Basel (Switzerland)


    We show that inclusive electron scattering at large momentum transfer allows a measurement of short-range properties of nuclear matter. This provides a very valuable constraint in selecting the calculations appropriate for predicting nuclear matter properties at the densities of astrophysical interest. (orig.)

  18. Antiproton-Proton Glory Scattering

    CERN Multimedia


    This experiment measures @*p and K|-p backwards scattering between 8 and 16 GeV/c in the Omega spectrometer using the S1 beam, with sensitivities of several events per nanobarn. The mechanism responsible for backward scattering in channels not mediated by particle exchange is not understood, and could be almost energy-independent glory scattering, especially since relatively high cross sections of 190~(@*p) and 120~(K|-p)nb have been measured earlier at 5~GeV/c. @p|-p backwards scattering is measured for monitoring purposes. The trigger requires a forward particle of momentum close to the beam momentum. Absence of light in the two forward Cerenkov counters indicates that the particle is a proton. Combinations of an incident @p|- and an outgoing K|+, or an incident K|- or @* and an outgoing @p|+, cover the following byproducts: @*p~@A~@p|+@p|- which is an (allowed) baryon exchange reaction, and the exotic exchange reactions @p|-p~@A~K|+Y K|-p~@A~@p|+Y|-, where Y|- may be the @S|- or the Y*|-(1385).

  19. Coupling between minimum scattering antennas

    DEFF Research Database (Denmark)

    Andersen, J.; Lessow, H; Schjær-Jacobsen, Hans


    Coupling between minimum scattering antennas (MSA's) is investigated by the coupling theory developed by Wasylkiwskyj and Kahn. Only rotationally symmetric power patterns are considered, and graphs of relative mutual impedance are presented as a function of distance and pattern parameters. Crossed......-dipoles and helices are considered in order to establish a correspondence with simple antenna structures....

  20. Pentagon diagrams of Bhabha scattering

    Energy Technology Data Exchange (ETDEWEB)

    Fleischer, J. [Bielefeld Univ. (Germany). Fakultaet fuer Physik]|[Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Riemann, T. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Gluza, J.; Kajda, K. [Uniwersytet Slaski, Katowice (Poland). Inst. Fizyki


    We report on tensor reduction of five point integrals needed for the evaluation of loop-by-loop corrections to Bhabha scattering. As an example we demonstrate the calculation of the rank two tensor integral with cancellation of the spurious Gram determinant in the denominator. The reduction scheme is worked out for arbitrary five point processes. (orig.)

  1. Pauli Principle and Pion Scattering (United States)

    Bethe, H. A.


    It is pointed out that if the Pauli principle is taken into account in the discussion of pion scattering by complex nuclei (as it ought, of course, to be) some rather implausible consequences of some earlier treatments of this problem can be avoided. (auth)


    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT. Hydrogen peroxide oxidized guaiacol to form tetramer particles that exhibited a strong resonance scattering (RS) peak at 530 nm in the presence of horseradish peroxidase (HRP) in citric acid-Na2HPO4 buffer solution of pH 4.4. The RS peak increased when the concentration of hydrogen peroxide increased.

  3. Thermally stimulated scattering in plasmas

    DEFF Research Database (Denmark)

    Dysthe, K. B.; Mjølhus, E.; Pécseli, H. L.


    A theory for stimulated scattering of a laser beam is formulated where the dominant nonlinearity is the ohmic heating of the plasma. The analysis is carried out with particular reference to experimental investigations of CO2 laser heating of linear discharge plasma. In the conditions characterizing...

  4. [Onychomycoses due to molds]. (United States)

    Chabasse, D; Pihet, M


    Onychomycoses represent about 30% of superficial mycosis that are encountered in Dermatology consults. Fungi such as dermatophytes, which are mainly found on the feet nails, cause nearly 50% of these onychopathies. Yeasts are predominantly present on hands, whereas non-dermatophytic moulds are very seldom involved in both foot and hand nails infections. According to literature, these moulds are responsible for 2 to 17% of onychomycoses. Nevertheless, we have to differentiate between onychomycoses due to pseudodermatophytes such as Neoscytalidium (ex-Scytalidium) and Onychocola canadensis, which present a high affinity for keratin, and onychomycoses due to filamentous fungi such as Aspergillus, Fusarium, Scopulariopsis, Acremonium... These saprophytic moulds are indeed most of the time considered as colonizers rather than real pathogens agents. Mycology and histopathology laboratories play an important role. They allow to identify the species that is involved in nail infection, but also to confirm parasitism by the fungus in the infected nails. Indeed, before attributing any pathogenic role to non-dermatophytic moulds, it is essential to precisely evaluate their pathogenicity through samples and accurate mycological and/or histological analysis. The treatment of onychomycoses due to non-dermatophytic moulds is difficult, as there is today no consensus. The choice of an antifungal agent will first depend on the species that is involved in the infection, but also on the severity of nail lesions and on the patient himself. In most cases, the onychomycosis will be cured with chemical or mechanical removing of the infected tissues, followed by a local antifungal treatment. In some cases, a systemic therapy will be discussed. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  5. Autocorrelation of scattered laser light for ultrasound-modulated optical tomography in dense turbid media. (United States)

    Li, Hui; Wang, Lihong V


    Based on measurement of the intensity autocorrelation function, a new method to determine the modulation depth of scattered laser light modulated by an ultrasonic wave in turbid media was applied to ultrasound-modulated optical tomography. Good signal-to-noise ratios and high sensitivities were demonstrated. Images of double optically absorbing objects buried in a highly optically scattering gel sample were obtained. The contrast was more than 10%, and the spatial resolution was approximately 2 mm.

  6. Autocorrelation of scattered laser light for ultrasound-modulated optical tomography in dense turbid media


    Li, Hui; Wang, Lihong V.


    Based on measurement of the intensity autocorrelation function, a new method to determine the modulation depth of scattered laser light modulated by an ultrasonic wave in turbid media was applied to ultrasound-modulated optical tomography. Good signal-to-noise ratios and high sensitivities were demonstrated. Images of double optically absorbing objects buried in a highly optically scattering gel sample were obtained. The contrast was more than 10%, and the spatial resolution was approximately...

  7. Applications of Raman and Surface-Enhanced Raman Scattering to the Analysis of Eukaryotic Samples (United States)

    Schulte, Franziska; Joseph, Virginia; Panne, Ulrich; Kneipp, Janina

    In this chapter, we discuss Raman scattering and surface-enhanced Raman scattering (SERS) for the analysis of cellular samples of plant and animal origin which are several tens to hundreds of microns in size. As was shown in the past several years, the favorable properties of noble metal nanostructures can be used to generate SERS signals in very complex biological samples such as cells, and result in an improved sensitivity and spatial resolution. Pollen grains, the physiological containers that produce the male gametes of seed plants, consist of a few vegetative cells and one generative cell, surrounded by a biopolymer shell. Their chemical composition has been a subject of research of plant physiologists, biochemists [1, 2], and lately even materials scientists [3, 4] for various reasons. In spite of a multitude of applied analytical approaches it could not be elucidated in its entirety yet. Animal cells from cell cultures have been a subject of intense studies due to their application in virtually all fields of biomedical research, ranging from studies of basic biological mechanisms to models for pharmaceutical and diagnostic research. Many aspects of all kinds of cellular processes including signalling, transport, and gene regulation have been elucidated, but many more facts about cell biology will need to be understood in order to efficiently address issues such as cancer, viral infection or genetic disorder. Using the information from spectroscopic methods, in particular combining normal Raman spectroscopy and SERS may open up new perspectives on cellular biochemistry. New sensitive Raman-based tools are being developed for the biochemical analysis of cellular processes [5-8].

  8. Comparative Study of Light Scattering from Hepatoma Cells and Hepatocytes (United States)

    Lin, Xiaogang; Wang, Rongrong; Guo, Yongcai; Gao, Chao; Guo, Xiaoen


    Primary liver cancer is one of the highest mortality malignant tumors in the world. China is a high occurrence area of primary liver cancer. Diagnosis of liver cancer, especially early diagnosis, is essential for improving patients' survival. Light scattering and measuring method is an emerging technology developed in recent decades, which has attracted a large number of biomedical researchers due to its advantages, such as fast, simple, high accuracy, good repeatability, and non-destructive. The hypothesis of this project is that there may be some different light scattering information between hepatoma cells and hepatocyte. Combined with the advantages of the dynamic light scattering method and the biological cytology, an experimental scheme to measure the light scattering information of cells was formulated. Hepatoma cells and hepatic cells were irradiated by a semiconductor laser (532 nm). And the Brookhaven BI-200SM wide-angle light scattering device and temperature control apparatus were adopted. The light scattering information of hepatoma cells and hepatic cells in vitro within the 15°C to 30°C temperature range was processed by a BI-9000AT digital autocorrelator. The following points were found: (a) the scattering intensities of human hepatic cells and hepatoma cells are nearly not affected by the temperature factor, and the former is always greater than the latter and (b) the relaxation time of hepatoma cells is longer than that of hepatic cells, and both the relaxation time are shortened with increasing temperature from 15°C to 25°C. It can be concluded that hepatoma cells could absorb more incident light than hepatic cells. The reason may be that there exists more protein and nucleic acid in cancerous cells than normal cells. Furthermore, based on the length relaxation time, a conclusion can be inferred that the Brownian movement of cancer cells is greater.

  9. The thermal neutron scattering cross section of {sup 86}Kr

    Energy Technology Data Exchange (ETDEWEB)

    Terburg, B.P.


    The availability of 27 1 STP krypton-86 gas, an isotope with unknown thermal neutron scattering cross section, was an excellent occasion to determine the (bound atom) scattering cross section and its coherent part by application of the neutron transmission method and neutron interferometry. The transmission method was applied in a diffractometer, a Larmor spectrometer and a TOF-spectrometer. In addition to {sup 86}Kr also natural krypton ({sup n}Kr) was used for sample in the diffractometer. The diffractometer measurements result in bound atom scattering cross sections {sigma}{sub s}=8.92(46) b for {sup 86}Kr and {sigma}{sub s}=7.08(95) b for {sup n}Kr. The Larmor transmission measurements lead to a final result {sigma}{sub s}=8.44(9) b for {sup 86}Kr. In the TOF-spectrometer the wavelength-dependent total cross section of water was determined. Coherent neutron scattering lengths were determined using the neutron interferometry method with a skew symmetric neutron interferometer. Scans with {sup 86}Kr and {sup n}Kr led to b{sub c}=8.07(26) fm for {sup 86}Kr and 7.72(33) fm for {sup n}Kr, corresponding to coherent scattering cross sections {sigma}{sub c}=8.18(53) b and 7.49(64) b respectively. Due to the large errors in the bound atom scattering cross section and coherent scattering cross section of {sup 86}Kr and {sup n}Kr, the incoherent cross section of both gases, {sigma}{sub i} = 0 within its inaccuracy, {sigma}{sub i}=0.26(54) b for {sup 86}Kr and {sigma}{sub i}=0.41(1.15) b for {sup n}Kr. (orig.).

  10. Improvements to the MST Thomson Scattering Diagnostic (United States)

    Adams, D. T.; Borchardt, M. T.; den Hartog, D. J.; Holly, D. J.; Kile, T.; Kubala, S. Z.; Jacobson, C. M.; Thomas, M. A.; Wallace, J. P.; Young, W. C.; MST Thomson Scattering Team


    Multiple upgrades to the MST Thomson Scattering diagnostic have been implemented to expand capabilities of the system. In the past, stray laser light prevented electron density measurements everywhere and temperature measurements for -z/a >0.75. To mitigate stray light, a new laser beamline is being commissioned that includes a longer entrance flight tube, close-fitting apertures, and baffles. A polarizer has been added to the collection optics to further reduce stray light. An absolute density calibration using Rayleigh scattering in argon will be performed. An insertable integrating sphere will provide a full-system spectral calibration as well as maps optical fibers to machine coordinates. Reduced transmission of the collection optics due to coatings from plasma-surface interactions is regularly monitored to inform timely replacements of the first lens. Long-wavelength filters have been installed to better characterize non-Maxwellian electron distribution features. Previous work has identified residual photons not described by a Maxwellian distribution during m =0 magnetic bursts. Further effort to characterize the distribution function will be described. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences program under Award No. DE-FC02-05ER54814.

  11. Nanoparticulate Impurities in Pharmaceutical-Grade Sugars and their Interference with Light Scattering-Based Analysis of Protein Formulations. (United States)

    Weinbuch, Daniel; Cheung, Jason K; Ketelaars, Jurgen; Filipe, Vasco; Hawe, Andrea; den Engelsman, John; Jiskoot, Wim


    In the present study we investigated the root-cause of an interference signal (100-200 nm) of sugar-containing solutions in dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA) and its consequences for the analysis of particles in biopharmaceutical drug products. Different sugars as well as sucrose of various purity grades, suppliers and lots were analyzed by DLS and NTA before and (only for sucrose) after treatment by ultrafiltration and diafiltration. Furthermore, Fourier transform infrared (FTIR) microscopy, scanning electron microscopy coupled energy-dispersive X-ray spectroscopy (SEM-EDX), and fluorescence spectroscopy were employed. The intensity of the interference signal differed between sugar types, sucrose of various purity grades, suppliers, and batches of the same supplier. The interference signal could be successfully eliminated from a sucrose solution by ultrafiltration (0.02 μm pore size). Nanoparticles, apparently composed of dextrans, ash components and aromatic colorants that were not completely removed during the sugar refinement process, were found responsible for the interference and were successfully purified from sucrose solutions. The interference signal of sugar-containing solutions in DLS and NTA is due to the presence of nanoparticulate impurities. The nanoparticles present in sucrose were identified as agglomerates of various impurities originating from raw materials.

  12. Effects of moderate pump and Stokes chirp on chirped-probe pulse femtosecond coherent anti-Stokes Raman scattering thermometry

    KAUST Repository

    Gu, Mingming


    The effects of moderate levels of chirp in the pump and Stokes pulses on chirped-probe-pulse femtosecond coherent anti-Stokes Raman scattering (CPP fs CARS) were investigated. The frequency chirp in the pump and Stokes pulses was introduced by placing SF11 glass disks with thicknesses of 10 mm or 20 mm in the optical path for these beams. The magnitude of the chirp in the probe beam was much greater and was induced by placing a 30-cm rod of SF10 glass in the beam path. The temperature measurements were performed in hydrogen/air non-premixed flames stabilized on a Hencken burner at equivalence ratios of 0.3, 0.5, 0.7, and 1.0. We performed measurements with no disks in pump and Stokes beam paths, and then with disks of 10 mm and 20 mm placed in both beam paths. The spectrum of the nonresonant background four-wave mixing signal narrowed considerably with increasing pump and Stokes chirp, while the resonant CARS signal was relatively unaffected. Consequently, the interference of the nonresonant background with the resonant CARS signal in the frequency-spread dephasing region of the spectrum was minimized. The increased rate of decay of the resonant CARS signal with increasing temperature was thus readily apparent. We have started to analyze the CPP fs CARS thermometry data and initial results indicate improved accuracy and precision are obtained due to moderate chirp in the pump and Stokes laser pulses.

  13. Ultralong-range sounding of the ionospheric HF channel using an ionosonde/direction finder with chirp modulation of the signal (United States)

    G. Vertogradov, G.; Uryadov, V. P.; Vertogradova, E. G.; Ponyatov, A. A.


    We present the results of experimental studies of propagation of short radio waves on a long transequatorial path of Laverton (Australia) — Rostov-on-Don, which were obtained with the help of an ionosonde/direction finder with chirp modulation of the signal. It is shown that conditions for propagation of anomalous signals by means of sideband reflection of radio waves from the Himalayan Hills and the Plateau of Iran and also due to scattering of radio waves from the high-latitude ionosphere of the northern hemisphere are realized on the given path. The propagation of radio waves is modeled with allowance for their scattering by anisotropic magnetic field-aligned irregularities of a high-latitude ionosphere, which are located on the northern wall of the main ionospheric trough of the F layer. It is shown that the results of the experiment agree well with the calculated data.

  14. Adenovirus Particle Quantification in Cell Lysates Using Light Scattering. (United States)

    Hohl, Adrian; Ramms, Anne Sophie; Dohmen, Christian; Mantwill, Klaus; Bielmeier, Andrea; Kolk, Andreas; Ruppert, Andreas; Nawroth, Roman; Holm, Per Sonne


    Adenoviral vector production for therapeutic applications is a well-established routine process. However, current methods for measurement of adenovirus particle titers as a quality characteristic require highly purified virus preparations. While purified virus is typically obtained in the last step of downstream purification, rapid and reliable methods for adenovirus particle quantification in intermediate products and crude lysates to allow for optimization and validation of cell cultures and intermediate downstream processing steps are currently not at hand. Light scattering is an established process to measure virus particles' size, though due to cell impurities, adequate quantification of adenovirus particles in cell lysates by light scattering has been impossible until today. This report describes a new method using light scattering to measure virus concentration in nonpurified cell lysates. Here we report application of light scattering, a routine method to measure virus particle size, to virus quantification in enzymatically conditioned crude lysates. Samples are incubated with phospholipase A2 and benzonase and filtered through a 0.22 μm filter cartridge prior to quantification by light scattering. Our results show that this treatment provides a precise method for fast and easy determination of total adenovirus particle numbers in cell lysates and is useful to monitor virus recovery throughout all downstream processing.

  15. Neutron scattering and models: Iron. Nuclear data and measurements series

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.B. [Argonne National Lab., IL (United States)


    Differential elastic and inelastic neutron-scattering cross sections of elemental iron are measured from 4.5 to 10 MeV in increments of {approx} 0.5 MeV. At each incident energy the measurements are made at forty or more scattering angles distributed between {approx} 17{degrees} and 160{degrees}, with emphasis on elastic scattering and inelastic scattering due to the excitation of the yrast 2{sup +} state. The measured data is combined with earlier lower-energy results from this laboratory, with recent high-precision {approx} 9.5 {yields} 15 MeV results from the Physilalisch Technische Bundesanstalt and with selected values from the literature to provide a detailed neutron-scattering data base extending from {approx} 1.5 to 26 MeV. This data is interpreted in the context of phenomenological spherical-optical and coupled-channels (vibrational and rotational) models, and physical implications discussed. Deformation, coupling, asymmetry and dispersive effects are explored. It is shown that, particularly in a collective context, a good description of the interaction of neutrons with iron is achieved over the energy range {approx} 0 {yields} 26 MeV, avoiding the dichotomy between high and low-energy interpretations found in previous work.

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

    Karam, Mostafa A.; Fung, Adrian K.


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

  17. Performance bounds on micro-Doppler estimation and adaptive waveform design using OFDM signals (United States)

    Sen, Satyabrata; Barhen, Jacob; Glover, Charles W.


    We analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a target having multiple rotating scatterers (e.g., rotor blades of a helicopter, propellers of a submarine). The presence of rotating scatterers introduces Doppler frequency modulation in the received signal by generating sidebands about the transmitted frequencies. This is called the micro-Doppler effects. The use of a frequency-diverse OFDM signal in this context enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. Therefore, to characterize the accuracy of micro-Doppler frequency estimation, we compute the Craḿer-Rao Bound (CRB) on the angular-velocity estimate of the target while considering the scatterer responses as deterministic but unknown nuisance parameters. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the transmitting OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations at different values of the signal-to-noise ratio (SNR) and the number of OFDM subcarriers. The CRB values not only decrease with the increase in the SNR values, but also reduce as we increase the number of subcarriers implying the significance of frequency-diverse OFDM waveforms. The improvement in estimation accuracy due to the adaptive waveform design is also numerically analyzed. Interestingly, we find that the relative decrease in the CRBs on the angular-velocity estimate is more pronounced for larger number of OFDM subcarriers.

  18. Performance Bounds on Micro-Doppler Estimation and Adaptive Waveform Design Using OFDM Signals

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Satyabrata [ORNL; Barhen, Jacob [ORNL; Glover, Charles Wayne [ORNL


    We analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a target having multiple rotating scatterers (e.g., rotor blades of a helicopter, propellers of a submarine). The presence of rotating scatterers introduces Doppler frequency modulation in the received signal by generating sidebands about the transmitted frequencies. This is called the micro-Doppler effects. The use of a frequency-diverse OFDM signal in this context enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. Therefore, to characterize the accuracy of micro-Doppler frequency estimation, we compute the Cram er-Rao Bound (CRB) on the angular-velocity estimate of the target while considering the scatterer responses as deterministic but unknown nuisance parameters. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the transmitting OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations at different values of the signal-to-noise ratio (SNR) and the number of OFDM subcarriers. The CRB values not only decrease with the increase in the SNR values, but also reduce as we increase the number of subcarriers implying the significance of frequency-diverse OFDM waveforms. The improvement in estimation accuracy due to the adaptive waveform design is also numerically analyzed. Interestingly, we find that the relative decrease in the CRBs on the angular-velocity estimate is more pronounced for larger number of OFDM subcarriers.

  19. Levels of detail analysis of microwave scattering from human head models for brain stroke detection

    Directory of Open Access Journals (Sweden)

    Awais Munawar Qureshi


    Full Text Available In this paper, we have presented a microwave scattering analysis from multiple human head models. This study incorporates different levels of detail in the human head models and its effect on microwave scattering phenomenon. Two levels of detail are taken into account; (i Simplified ellipse shaped head model (ii Anatomically realistic head model, implemented using 2-D geometry. In addition, heterogenic and frequency-dispersive behavior of the brain tissues has also been incorporated in our head models. It is identified during this study that the microwave scattering phenomenon changes significantly once the complexity of head model is increased by incorporating more details using magnetic resonance imaging database. It is also found out that the microwave scattering results match in both types of head model (i.e., geometrically simple and anatomically realistic, once the measurements are made in the structurally simplified regions. However, the results diverge considerably in the complex areas of brain due to the arbitrary shape interface of tissue layers in the anatomically realistic head model. After incorporating various levels of detail, the solution of subject microwave scattering problem and the measurement of transmitted and backscattered signals were obtained using finite element method. Mesh convergence analysis was also performed to achieve error free results with a minimum number of mesh elements and a lesser degree of freedom in the fast computational time. The results were promising and the E-Field values converged for both simple and complex geometrical models. However, the E-Field difference between both types of head model at the same reference point differentiated a lot in terms of magnitude. At complex location, a high difference value of 0.04236 V/m was measured compared to the simple location, where it turned out to be 0.00197 V/m. This study also contributes to provide a comparison analysis between the direct and iterative

  20. Spontaneous and stimulated Brillouin scattering in single-mode silica optical fibers (United States)

    Yeniay, Aydin

    This thesis describes an experimental investigation of Brillouin scattering in silica based single mode optical fibers at IR communication wavelengths (λ = 1550nm). We have investigated the scattering process in spontaneous and stimulated regimes by taking into account of the gain spectrum evolution, stimulated Brillouin scattering (SBS) threshold and polarization properties using laser sources with different spectral lineshapes. We have shown that several acoustic resonance modes, depending on the waveguide properties, exist in the spontaneous regime, but they decay as the process becomes stimulated. In the stimulated regime, only the main Brillouin peak persists with a linewidth approximately 10 times narrower than that in the spontaneous regime. Our results on the linewidth narrowing are in an agreement with the theory, which considers thermal noise fluctuations as the origin of Brillouin scattering in undepleted-pump regime. Moreover, we have found that the lineshape of the SBS light is identical to the input laser lineshape, with a resolution bandwidth that is equal to the SBS linewidth of the medium (7-12 MHz), which makes SBS a practical tool for laser linewidth measurements. In the study of polarization properties of Brillouin scattering, we specifically determined the SBS threshold and Degree of Polarization (DOP) of Brillouin light with respect to the state of polarization (SOP) and DOP of the input laser source. It is found that, for linearly polarized input signal (100% DOP); Rayleigh and Spontaneous Brillouin scattered signals have the DOP of 33%, while the Stimulated Brillouin scattered light has a DOP of 95%. On the other hand, for a depolarized input signal (DOP of 0%); Rayleigh, Spontaneous and Stimulated Brillouin scattered light have the same DOP of 5%. We also found that the depolarized signal yields 1dB higher SBS threshold than the polarized signal as oppose to earlier prediction of 3dB. A possible explanation for the discrepancy is given by