Foreign body detection in food materials using compton scattered x-rays

NASA Astrophysics Data System (ADS)

McFarlane, Nigel James Bruce

This thesis investigated the application of X-ray Compton scattering to the problem of foreign body detection in food. The methods used were analytical modelling, simulation and experiment. A criterion was defined for detectability, and a model was developed for predicting the minimum time required for detection. The model was used to predict the smallest detectable cubes of air, glass, plastic and steel. Simulations and experiments were performed on voids and glass in polystyrene phantoms, water, coffee and muesli. Backscatter was used to detect bones in chicken meat. The effects of geometry and multiple scatter on contrast, signal-to-noise, and detection time were simulated. Compton scatter was compared with transmission, and the effect of inhomogeneity was modelled. Spectral shape was investigated as a means of foreign body detection. A signal-to-noise ratio of 7.4 was required for foreign body detection in food. A 0.46 cm cube of glass or a 1.19 cm cube of polystyrene were detectable in a 10 cm cube of water in one second. The minimum time to scan a whole sample varied as the 7th power of the foreign body size, and the 5th power of the sample size. Compton scatter inspection produced higher contrasts than transmission, but required longer measurement times because of the low number of photon counts. Compton scatter inspection of whole samples was very slow compared to production line speeds in the food industry. There was potential for Compton scatter in applications which did not require whole-sample scanning, such as surface inspection. There was also potential in the inspection of inhomogeneous samples. The multiple scatter fraction varied from 25% to 55% for 2 to 10 cm cubes of water, but did not have a large effect on the detection time. The spectral shape gave good contrasts and signal-to-noise ratios in the detection of chicken bones.

On the Concept of Random Orientation in Far-Field Electromagnetic Scattering by Nonspherical Particles

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Yurkin, Maxim A.

2017-01-01

Although the model of randomly oriented nonspherical particles has been used in a great variety of applications of far-field electromagnetic scattering, it has never been defined in strict mathematical terms. In this Letter we use the formalism of Euler rigid-body rotations to clarify the concept of statistically random particle orientations and derive its immediate corollaries in the form of most general mathematical properties of the orientation-averaged extinction and scattering matrices. Our results serve to provide a rigorous mathematical foundation for numerous publications in which the notion of randomly oriented particles and its light-scattering implications have been considered intuitively obvious.

Simulation electromagnetic scattering on bodies through integral equation and neural networks methods

NASA Astrophysics Data System (ADS)

Lvovich, I. Ya; Preobrazhenskiy, A. P.; Choporov, O. N.

2018-05-01

The paper deals with the issue of electromagnetic scattering on a perfectly conducting diffractive body of a complex shape. Performance calculation of the body scattering is carried out through the integral equation method. Fredholm equation of the second time was used for calculating electric current density. While solving the integral equation through the moments method, the authors have properly described the core singularity. The authors determined piecewise constant functions as basic functions. The chosen equation was solved through the moments method. Within the Kirchhoff integral approach it is possible to define the scattered electromagnetic field, in some way related to obtained electrical currents. The observation angles sector belongs to the area of the front hemisphere of the diffractive body. To improve characteristics of the diffractive body, the authors used a neural network. All the neurons contained a logsigmoid activation function and weighted sums as discriminant functions. The paper presents the matrix of weighting factors of the connectionist model, as well as the results of the optimized dimensions of the diffractive body. The paper also presents some basic steps in calculation technique of the diffractive bodies, based on the combination of integral equation and neural networks methods.

An O(N squared) method for computing the eigensystem of N by N symmetric tridiagonal matrices by the divide and conquer approach

NASA Technical Reports Server (NTRS)

Gill, Doron; Tadmor, Eitan

1988-01-01

An efficient method is proposed to solve the eigenproblem of N by N Symmetric Tridiagonal (ST) matrices. Unlike the standard eigensolvers which necessitate O(N cubed) operations to compute the eigenvectors of such ST matrices, the proposed method computes both the eigenvalues and eigenvectors with only O(N squared) operations. The method is based on serial implementation of the recently introduced Divide and Conquer (DC) algorithm. It exploits the fact that by O(N squared) of DC operations, one can compute the eigenvalues of N by N ST matrix and a finite number of pairs of successive rows of its eigenvector matrix. The rest of the eigenvectors--all of them or one at a time--are computed by linear three-term recurrence relations. Numerical examples are presented which demonstrate the superiority of the proposed method by saving an order of magnitude in execution time at the expense of sacrificing a few orders of accuracy.

Scattering from finite bodies of translation - Plates, curved surfaces, and noncircular cylinders

NASA Astrophysics Data System (ADS)

Medgyesi-Mitschang, L. N.; Putnam, J. M.

1983-11-01

Electromagnetic scattering from finite, conducting bodies of translation (BOT) is examined using a formulation based on the electric field integral equation (EFIE) and solved by the method of moments (MM). The present approach provides a systematic, unified treatment for a wide class of finite, thin scatterers at all angles of illumination and polarization. Both concave and convex surfaces are considered. An entire-domain Galerkin expansion along one dimension of the body and a piecewise continuous one along the other are used to represent the unknown current variations. The scattering cross sections, obtained with this formulation, are compared with published results using more specialized methods and further confirmed by experimental measurements.

Comparison of alloy disorder scatterings in Ga- and N-polar AlGaN/GaN heterostructures

NASA Astrophysics Data System (ADS)

Kang, He; Li, Hui-Jie; Yang, Shao-Yan; Zhang, Wei; Zhu, Ming; Liu, Li; Li, Nan

2018-01-01

The two-dimensional electron gas (2DEG) mobilities limited by alloy disorder (AD) scattering in both Ga- and N-polar AlGaN/GaN heterostructures are investigated. It was found that the AD scattering limited electron mobility in N-polar heterostructures is on the order of 103-104 cm2/Vs, which is comparable to the optical phonon scattering at room-temperature. In comparison, the AD scattering in Ga-polar samples is much less important. Moreover, the electron mobility decreases with the 2DEG density in the Ga-polar device but shows a reverse trend in the N-polar counterpart. This is found to be caused by the rather different electric field distributions in Ga- and N-polar AlGaN/GaN heterostructures. In addition, we find that an AlN interlayer can effectively reduce the alloy scattering, mainly due to the large band offset between AlN and GaN. The calculated mobilities have been compared with the experiment results and good agreements are found. We believe that our results are important for the design of AlGaN/GaN heterostructure-based devices, especially the N-polar ones.

Roy-Steiner equations for πN scattering

NASA Astrophysics Data System (ADS)

de Elvira, J. Ruiz; Ditsche, C.; Hoferichter, M.; Kubis, B.; Meißner, U.-G.

2015-10-01

In this talk, we briefly review our ongoing collaboration to precisely determine the low-energy πN scattering amplitude by means of Roy-Steiner equations. After giving a brief overview of this system of dispersive equations and their application to πN scattering, we proceed to solve for the lower partial waves of the s-channel (πN → πN) and the t-channel l( {π π to bar NN} right) sub-problems.

High-energy gravitational scattering and the general relativistic two-body problem

NASA Astrophysics Data System (ADS)

Damour, Thibault

2018-02-01

A technique for translating the classical scattering function of two gravitationally interacting bodies into a corresponding (effective one-body) Hamiltonian description has been recently introduced [Phys. Rev. D 94, 104015 (2016), 10.1103/PhysRevD.94.104015]. Using this technique, we derive, for the first time, to second-order in Newton's constant (i.e. one classical loop) the Hamiltonian of two point masses having an arbitrary (possibly relativistic) relative velocity. The resulting (second post-Minkowskian) Hamiltonian is found to have a tame high-energy structure which we relate both to gravitational self-force studies of large mass-ratio binary systems, and to the ultra high-energy quantum scattering results of Amati, Ciafaloni and Veneziano. We derive several consequences of our second post-Minkowskian Hamiltonian: (i) the need to use special phase-space gauges to get a tame high-energy limit; and (ii) predictions about a (rest-mass independent) linear Regge trajectory behavior of high-angular-momenta, high-energy circular orbits. Ways of testing these predictions by dedicated numerical simulations are indicated. We finally indicate a way to connect our classical results to the quantum gravitational scattering amplitude of two particles, and we urge amplitude experts to use their novel techniques to compute the two-loop scattering amplitude of scalar masses, from which one could deduce the third post-Minkowskian effective one-body Hamiltonian.

Compound matrices

NASA Astrophysics Data System (ADS)

Kravvaritis, Christos; Mitrouli, Marilena

2009-02-01

This paper studies the possibility to calculate efficiently compounds of real matrices which have a special form or structure. The usefulness of such an effort lies in the fact that the computation of compound matrices, which is generally noneffective due to its high complexity, is encountered in several applications. A new approach for computing the Singular Value Decompositions (SVD's) of the compounds of a matrix is proposed by establishing the equality (up to a permutation) between the compounds of the SVD of a matrix and the SVD's of the compounds of the matrix. The superiority of the new idea over the standard method is demonstrated. Similar approaches with some limitations can be adopted for other matrix factorizations, too. Furthermore, formulas for the n - 1 compounds of Hadamard matrices are derived, which dodge the strenuous computations of the respective numerous large determinants. Finally, a combinatorial counting technique for finding the compounds of diagonal matrices is illustrated.

Stochastic local operations and classical communication (SLOCC) and local unitary operations (LU) classifications of n qubits via ranks and singular values of the spin-flipping matrices

NASA Astrophysics Data System (ADS)

Li, Dafa

2018-06-01

We construct ℓ -spin-flipping matrices from the coefficient matrices of pure states of n qubits and show that the ℓ -spin-flipping matrices are congruent and unitary congruent whenever two pure states of n qubits are SLOCC and LU equivalent, respectively. The congruence implies the invariance of ranks of the ℓ -spin-flipping matrices under SLOCC and then permits a reduction of SLOCC classification of n qubits to calculation of ranks of the ℓ -spin-flipping matrices. The unitary congruence implies the invariance of singular values of the ℓ -spin-flipping matrices under LU and then permits a reduction of LU classification of n qubits to calculation of singular values of the ℓ -spin-flipping matrices. Furthermore, we show that the invariance of singular values of the ℓ -spin-flipping matrices Ω 1^{(n)} implies the invariance of the concurrence for even n qubits and the invariance of the n-tangle for odd n qubits. Thus, the concurrence and the n-tangle can be used for LU classification and computing the concurrence and the n-tangle only performs additions and multiplications of coefficients of states.

Development of a Body Shield for Small Animal PET System to Reduce Random and Scatter Coincidences

NASA Astrophysics Data System (ADS)

Wada, Yasuhiro; Yamamoto, Seiichi; Watanabe, Yasuyoshi

2015-02-01

For small animal positron emission tomography (PET) research using high radioactivity, such as dynamic studies, the resulting high random coincidence rate of the system degrades image quality. The random coincidence rate is increased not only by the gamma photons from inside the axial-field-of-view (axial-FOV) of the PET system but also by those from outside the axial-FOV. For brain imaging in small animal studies, significant interference is observed from gamma photons emitted from the body. Single gamma photons from the body enter the axial-FOV and increase the random and scatter coincidences. Shielding against the gamma photons from outside the axial-FOV would improve the image quality. For this purpose, we developed a body shield for a small animal PET system, the microPET Primate 4-ring system, and evaluated its performance. The body shield is made of 9-mm-thick lead and it surrounds most of a rat's body. We evaluated the effectiveness of the body shield using a head phantom and a body phantom with a radioactivity concentration ratio of 1:2 and a maximum total activity of approximately 250 MBq. The random coincidence rate was dramatically decreased to 1/10, and the noise equivalent count rate (NECR) was increased 6 times with an activity of 7 MBq in the head phantom. The true count rate was increased to 35% due to the decrease in system deadtime. The average scatter fraction was decreased to 1/2.5 with the body shield. Count rate measurements of rat were also conducted with an injection activity of approximately 25 MBq of [C-11]N,N-dimethyl-2-(2-amino-4-cyanophenylthio) benzylamine ([C-11]DASB) and approximately 70 and 310 MBq of 2-deoxy-2-(F-18)fluoro-D-glucose ([F-18]FDG). Using the body shield, [F-18]FDG images of rats were improved by increasing the amount of radioactivity injected. The body shield designed for small animal PET systems is a promising tool for improving image quality and quantitation accuracy in small animal molecular imaging research.

General integrable n-level, many-mode Janes-Cummings-Dicke models and classical r-matrices with spectral parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skrypnyk, T., E-mail: taras.skrypnyk@unimib.it, E-mail: tskrypnyk@imath.kiev.ua

Using the technique of classical r-matrices and quantum Lax operators, we construct the most general form of the quantum integrable “n-level, many-mode” spin-boson Jaynes-Cummings-Dicke-type hamiltonians describing an interaction of a molecule of N n-level atoms with many modes of electromagnetic field and containing, in general, additional non-linear interaction terms. We explicitly obtain the corresponding quantum Lax operators and spin-boson analogs of the generalized Gaudin hamiltonians and prove their quantum commutativity. We investigate symmetries of the obtained models that are associated with the geometric symmetries of the classical r-matrices and construct the corresponding algebra of quantum integrals. We consider in detailmore » three classes of non-skew-symmetric classical r-matrices with spectral parameters and explicitly obtain the corresponding quantum Lax operators and Jaynes-Cummings-Dicke-type hamiltonians depending on the considered r-matrix.« less

Modeling of light scattering by icy bodies

NASA Astrophysics Data System (ADS)

Kolokolova, L.; Mackowski, D.; Pitman, K.; Verbiscer, A.; Buratti, B.; Momary, T.

2014-07-01

As a result of ground-based, space-based, and in-situ spacecraft mission observations, a great amount of photometric, polarimetric, and spectroscopic data of icy bodies (satellites of giant planets, Kuiper Belt objects, comet nuclei, and icy particles in cometary comae and rings) has been accumulated. These data have revealed fascinating light-scattering phenomena, such as the opposition surge resulting from coherent backscattering and shadow hiding and the negative polarization associated with them. Near-infrared (NIR) spectra of these bodies are especially informative as the depth, width, and shape of the absorption bands of ice are sensitive not only to the ice abundance but also to the size of icy grains. Numerous NIR spectra obtained by Cassini's Visual and Infrared Mapping Spectrometer (VIMS) have been used to map the microcharacteristics of the icy satellites [1] and rings of Saturn [2]. VIMS data have also permitted a study of the opposition surge for icy satellites of Saturn [3], showing that coherent backscattering affects not only brightness and polarization of icy bodies but also their spectra [4]. To study all of the light-scattering phenomena that affect the photopolarimetric and spectroscopic characteristics of icy bodies, including coherent backscattering, requires computer modeling that rigorously considers light scattering by a large number of densely packed small particles that form either layers (in the case of regolith) or big clusters (ring and comet particles) . Such opportunity has appeared recently with a development of a new version MSTM4 of the Multi-Sphere T-Matrix code [5]. Simulations of reflectance and absorbance spectra of a ''target'' (particle layer or cluster) require that the dimensions of the target be significantly larger than the wavelength, sphere radius, and layer thickness. For wavelength-sized spheres and packing fractions typical of regolith, targets can contain dozens of thousands of spheres that, with the original MSTM

Phonon Lifetime Observation in Epitaxial ScN Film with Inelastic X-Ray Scattering Spectroscopy.

PubMed

Uchiyama, H; Oshima, Y; Patterson, R; Iwamoto, S; Shiomi, J; Shimamura, K

2018-06-08

Phonon-phonon scattering dominates the thermal properties in nonmetallic materials, and it directly influences device performance in applications. The understanding of the scattering has been progressing using computational approaches, and the direct and systematic observation of phonon modes that include momentum dependences is desirable. We report experimental data on the phonon dispersion curves and lifetimes in an epitaxially grown ScN film using inelastic x-ray scattering measurements. The momentum dependence of the optical phonon lifetimes is estimated from the spectral width, and the highest-energy phonon mode around the zone center is found to possess a short lifetime of 0.21 ps. A comparison with first-principles calculations shows that our observed phonon lifetimes are quantitatively explained by three-body phonon-phonon interactions.

Phonon Lifetime Observation in Epitaxial ScN Film with Inelastic X-Ray Scattering Spectroscopy

NASA Astrophysics Data System (ADS)

Uchiyama, H.; Oshima, Y.; Patterson, R.; Iwamoto, S.; Shiomi, J.; Shimamura, K.

2018-06-01

Phonon-phonon scattering dominates the thermal properties in nonmetallic materials, and it directly influences device performance in applications. The understanding of the scattering has been progressing using computational approaches, and the direct and systematic observation of phonon modes that include momentum dependences is desirable. We report experimental data on the phonon dispersion curves and lifetimes in an epitaxially grown ScN film using inelastic x-ray scattering measurements. The momentum dependence of the optical phonon lifetimes is estimated from the spectral width, and the highest-energy phonon mode around the zone center is found to possess a short lifetime of 0.21 ps. A comparison with first-principles calculations shows that our observed phonon lifetimes are quantitatively explained by three-body phonon-phonon interactions.

Many-Body Effect in Spin Dephasing in n-Type GaAs Quantum Wells

NASA Astrophysics Data System (ADS)

Weng, Ming-Qi; Wu, Ming-Wei

2005-03-01

By constructing and numerically solving the kinetic Bloch equations we perform a many-body study of the spin dephasing due to the D'yakonov-Perel' effect in n-type GaAs (100) quantum wells for high temperatures. In our study, we include the spin-conserving scattering such as the electron-phonon, the electron-nonmagnetic impurity as well as the electron-electron Coulomb scattering into consideration. The dephasing obtained from our theory contains both the single-particle and the many-body contributions with the latter originating from the inhomogeneous broadening introduced by the DP term [J. Supercond.: Incorp. Novel Magn. 14 (2001) 245 Eur. Phys. J. B 18 (2000) 373]. Our result agrees very well with the experimental data [Phys. Rev. B 62 (2000) 13034] of Malinowski et al. We further show that in the case we study, the spin dephasing is dominated by the many-body effect.

Anisotropic elastic scattering of stripe/line-shaped scatters to two-dimensional electron gas: Model and illustrations in a nonpolar AlGaN/GaN hetero-junction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jinfeng, E-mail: jfzhang@xidian.edu.cn; Li, Yao; Yan, Ran

In a semiconductor hetero-junction, the stripe/line-shaped scatters located at the hetero-interface lead to the anisotropic transport of two-dimensional electron gas (2DEG). The elastic scattering of infinitely long and uniform stripe/line-shaped scatters to 2DEG is theoretically investigated based on a general theory of anisotropic 2DEG transport [J. Schliemann and D. Loss, Phys. Rev. B 68(16), 165311 (2003)], and the resulting 2DEG mobility along the applied electrical field is modeled to be a function of the angle between the field and the scatters. The anisotropy of the scattering and the mobility originate in essence from that the stripe/line-shaped scatters act upon themore » injecting two-dimensional wave vector by changing only its component perpendicular to the scatters. Three related scattering mechanisms in a nonpolar AlGaN/GaN hetero-junction are discussed as illustrations, including the striated morphology caused interface roughness scattering, and the polarization induced line charge dipole scattering and the misfit dislocation scattering at the AlGaN/GaN interface. Different anisotropic behaviors of the mobility limited by these scattering mechanisms are demonstrated, but analysis shows that all of them are determined by the combined effects of the anisotropic bare scattering potential and the anisotropic dielectric response of the 2DEG.« less

Singularity in the Laboratory Frame Angular Distribution Derived in Two-Body Scattering Theory

ERIC Educational Resources Information Center

Dick, Frank; Norbury, John W.

2009-01-01

The laboratory (lab) frame angular distribution derived in two-body scattering theory exhibits a singularity at the maximum lab scattering angle. The singularity appears in the kinematic factor that transforms the centre of momentum (cm) angular distribution to the lab angular distribution. We show that it is caused in the transformation by the…

Improved Convergence Rate of Multi-Group Scattering Moment Tallies for Monte Carlo Neutron Transport Codes

NASA Astrophysics Data System (ADS)

Nelson, Adam

Multi-group scattering moment matrices are critical to the solution of the multi-group form of the neutron transport equation, as they are responsible for describing the change in direction and energy of neutrons. These matrices, however, are difficult to correctly calculate from the measured nuclear data with both deterministic and stochastic methods. Calculating these parameters when using deterministic methods requires a set of assumptions which do not hold true in all conditions. These quantities can be calculated accurately with stochastic methods, however doing so is computationally expensive due to the poor efficiency of tallying scattering moment matrices. This work presents an improved method of obtaining multi-group scattering moment matrices from a Monte Carlo neutron transport code. This improved method of tallying the scattering moment matrices is based on recognizing that all of the outgoing particle information is known a priori and can be taken advantage of to increase the tallying efficiency (therefore reducing the uncertainty) of the stochastically integrated tallies. In this scheme, the complete outgoing probability distribution is tallied, supplying every one of the scattering moment matrices elements with its share of data. In addition to reducing the uncertainty, this method allows for the use of a track-length estimation process potentially offering even further improvement to the tallying efficiency. Unfortunately, to produce the needed distributions, the probability functions themselves must undergo an integration over the outgoing energy and scattering angle dimensions. This integration is too costly to perform during the Monte Carlo simulation itself and therefore must be performed in advance by way of a pre-processing code. The new method increases the information obtained from tally events and therefore has a significantly higher efficiency than the currently used techniques. The improved method has been implemented in a code system

Encoding the structure of many-body localization with matrix product operators

NASA Astrophysics Data System (ADS)

Pekker, David; Clark, Bryan K.

2017-01-01

Anderson insulators are noninteracting disordered systems which have localized single-particle eigenstates. The interacting analog of Anderson insulators are the many-body localized (MBL) phases. The spectrum of the many-body eigenstates of an Anderson insulator is efficiently represented as a set of product states over the single-particle modes. We show that product states over matrix product operators of small bond dimension is the corresponding efficient description of the spectrum of an MBL insulator. In this language all of the many-body eigenstates are encoded by matrix product states (i.e., density matrix renormalization group wave functions) consisting of only two sets of low bond dimension matrices per site: the Gi matrices corresponding to the local ground state on site i and the Ei matrices corresponding to the local excited state. All 2n eigenstates can be generated from all possible combinations of these sets of matrices.

Ballistic Transport for Limit-Periodic Jacobi Matrices with Applications to Quantum Many-Body Problems

NASA Astrophysics Data System (ADS)

Fillman, Jake

2017-03-01

We study Jacobi matrices that are uniformly approximated by periodic operators. We show that if the rate of approximation is sufficiently rapid, then the associated quantum dynamics are ballistic in a rather strong sense; namely, the (normalized) Heisenberg evolution of the position operator converges strongly to a self-adjoint operator that is injective on the space of absolutely summable sequences. In particular, this means that all transport exponents corresponding to well-localized initial states are equal to one. Our result may be applied to a class of quantum many-body problems. Specifically, we establish a lower bound on the Lieb-Robinson velocity for an isotropic XY spin chain on the integers with limit-periodic couplings.

Deterministic matrices matching the compressed sensing phase transitions of Gaussian random matrices

PubMed Central

Monajemi, Hatef; Jafarpour, Sina; Gavish, Matan; Donoho, David L.; Ambikasaran, Sivaram; Bacallado, Sergio; Bharadia, Dinesh; Chen, Yuxin; Choi, Young; Chowdhury, Mainak; Chowdhury, Soham; Damle, Anil; Fithian, Will; Goetz, Georges; Grosenick, Logan; Gross, Sam; Hills, Gage; Hornstein, Michael; Lakkam, Milinda; Lee, Jason; Li, Jian; Liu, Linxi; Sing-Long, Carlos; Marx, Mike; Mittal, Akshay; Monajemi, Hatef; No, Albert; Omrani, Reza; Pekelis, Leonid; Qin, Junjie; Raines, Kevin; Ryu, Ernest; Saxe, Andrew; Shi, Dai; Siilats, Keith; Strauss, David; Tang, Gary; Wang, Chaojun; Zhou, Zoey; Zhu, Zhen

2013-01-01

In compressed sensing, one takes samples of an N-dimensional vector using an matrix A, obtaining undersampled measurements . For random matrices with independent standard Gaussian entries, it is known that, when is k-sparse, there is a precisely determined phase transition: for a certain region in the (,)-phase diagram, convex optimization typically finds the sparsest solution, whereas outside that region, it typically fails. It has been shown empirically that the same property—with the same phase transition location—holds for a wide range of non-Gaussian random matrix ensembles. We report extensive experiments showing that the Gaussian phase transition also describes numerous deterministic matrices, including Spikes and Sines, Spikes and Noiselets, Paley Frames, Delsarte-Goethals Frames, Chirp Sensing Matrices, and Grassmannian Frames. Namely, for each of these deterministic matrices in turn, for a typical k-sparse object, we observe that convex optimization is successful over a region of the phase diagram that coincides with the region known for Gaussian random matrices. Our experiments considered coefficients constrained to for four different sets , and the results establish our finding for each of the four associated phase transitions. PMID:23277588

Born scattering of long-period body waves

NASA Astrophysics Data System (ADS)

Dalkolmo, Jörg; Friederich, Wolfgang

2000-09-01

The Born approximation is applied to the modelling of the propagation of deeply turning long-period body waves through heterogeneities in the lowermost mantle. We use an exact Green's function for a spherically symmetric earth model that also satisfies the appropriate boundary conditions at internal boundaries and the surface of the earth. The scattered displacement field is obtained by a numerical quadrature of the product of the Green's function, the exciting wavefield and structural perturbations. We study three examples: scattering of long-period P waves from a plume rising from the core-mantle boundary (CMB), generation of long-period precursors to PKIKP by strong, localized scatterers at the CMB, and propagation of core-diffracted P waves through large-scale heterogeneities in D''. The main results are as follows: (1) the signals scattered from a realistic plume are small with relative amplitudes of less than 2 per cent at a period of 20s, rendering plume detection a fairly difficult task; (2) strong heterogeneities at the CMB of appropriate size may produce observable long-period precursors to PKIKP in spite of the presence of a diffraction from the PKP-B caustic; (3) core-diffracted P waves (Pdiff) are sensitive to structure in D'' far off the geometrical ray path and also far beyond the entry and exit points of the ray into and out of D'' sensitivity kernels exhibit ring-shaped patterns of alternating sign reminiscent of Fresnel zones; (4) Pdiff also shows a non-negligible sensitivity to shear wave velocity in D'' (5) down to periods of 40s, the Born approximation is sufficiently accurate to allow waveform modelling of Pdiff through large-scale heterogeneities in D'' of up to 5 per cent.

Expansion of Tabulated Scattering Matrices in Generalized Spherical Functions

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.; Geogdzhayev, Igor V.; Yang, Ping

2016-01-01

An efficient way to solve the vector radiative transfer equation for plane-parallel turbid media is to Fourier-decompose it in azimuth. This methodology is typically based on the analytical computation of the Fourier components of the phase matrix and is predicated on the knowledge of the coefficients appearing in the expansion of the normalized scattering matrix in generalized spherical functions. Quite often the expansion coefficients have to be determined from tabulated values of the scattering matrix obtained from measurements or calculated by solving the Maxwell equations. In such cases one needs an efficient and accurate computer procedure converting a tabulated scattering matrix into the corresponding set of expansion coefficients. This short communication summarizes the theoretical basis of this procedure and serves as the user guide to a simple public-domain FORTRAN program.

Further thoughts on the utility of risk matrices.

PubMed

Ball, David J; Watt, John

2013-11-01

Risk matrices are commonly encountered devices for rating hazards in numerous areas of risk management. Part of their popularity is predicated on their apparent simplicity and transparency. Recent research, however, has identified serious mathematical defects and inconsistencies. This article further examines the reliability and utility of risk matrices for ranking hazards, specifically in the context of public leisure activities including travel. We find that (1) different risk assessors may assign vastly different ratings to the same hazard, (2) even following lengthy reflection and learning scatter remains high, and (3) the underlying drivers of disparate ratings relate to fundamentally different worldviews, beliefs, and a panoply of psychosocial factors that are seldom explicitly acknowledged. It appears that risk matrices when used in this context may be creating no more than an artificial and even untrustworthy picture of the relative importance of hazards, which may be of little or no benefit to those trying to manage risk effectively and rationally. © 2013 Society for Risk Analysis.

Multiphoton Scattering Tomography with Coherent States.

PubMed

Ramos, Tomás; García-Ripoll, Juan José

2017-10-13

In this work we develop an experimental procedure to interrogate the single- and multiphoton scattering matrices of an unknown quantum system interacting with propagating photons. Our proposal requires coherent state laser or microwave inputs and homodyne detection at the scatterer's output, and provides simultaneous information about multiple-elastic and inelastic-segments of the scattering matrix. The method is resilient to detector noise and its errors can be made arbitrarily small by combining experiments at various laser powers. Finally, we show that the tomography of scattering has to be performed using pulsed lasers to efficiently gather information about the nonlinear processes in the scatterer.

A sensitivity analysis method for the body segment inertial parameters based on ground reaction and joint moment regressor matrices.

PubMed

Futamure, Sumire; Bonnet, Vincent; Dumas, Raphael; Venture, Gentiane

2017-11-07

This paper presents a method allowing a simple and efficient sensitivity analysis of dynamics parameters of complex whole-body human model. The proposed method is based on the ground reaction and joint moment regressor matrices, developed initially in robotics system identification theory, and involved in the equations of motion of the human body. The regressor matrices are linear relatively to the segment inertial parameters allowing us to use simple sensitivity analysis methods. The sensitivity analysis method was applied over gait dynamics and kinematics data of nine subjects and with a 15 segments 3D model of the locomotor apparatus. According to the proposed sensitivity indices, 76 segments inertial parameters out the 150 of the mechanical model were considered as not influent for gait. The main findings were that the segment masses were influent and that, at the exception of the trunk, moment of inertia were not influent for the computation of the ground reaction forces and moments and the joint moments. The same method also shows numerically that at least 90% of the lower-limb joint moments during the stance phase can be estimated only from a force-plate and kinematics data without knowing any of the segment inertial parameters. Copyright © 2017 Elsevier Ltd. All rights reserved.

On the extreme value statistics of normal random matrices and 2D Coulomb gases: Universality and finite N corrections

NASA Astrophysics Data System (ADS)

Ebrahimi, R.; Zohren, S.

2018-03-01

In this paper we extend the orthogonal polynomials approach for extreme value calculations of Hermitian random matrices, developed by Nadal and Majumdar (J. Stat. Mech. P04001 arXiv:1102.0738), to normal random matrices and 2D Coulomb gases in general. Firstly, we show that this approach provides an alternative derivation of results in the literature. More precisely, we show convergence of the rescaled eigenvalue with largest modulus of a normal Gaussian ensemble to a Gumbel distribution, as well as universality for an arbitrary radially symmetric potential. Secondly, it is shown that this approach can be generalised to obtain convergence of the eigenvalue with smallest modulus and its universality for ring distributions. Most interestingly, the here presented techniques are used to compute all slowly varying finite N correction of the above distributions, which is important for practical applications, given the slow convergence. Another interesting aspect of this work is the fact that we can use standard techniques from Hermitian random matrices to obtain the extreme value statistics of non-Hermitian random matrices resembling the large N expansion used in context of the double scaling limit of Hermitian matrix models in string theory.

Poles of the Zagreb analysis partial-wave T matrices

NASA Astrophysics Data System (ADS)

Batinić, M.; Ceci, S.; Švarc, A.; Zauner, B.

2010-09-01

The Zagreb analysis partial-wave T matrices included in the Review of Particle Physics [by the Particle Data Group (PDG)] contain Breit-Wigner parameters only. As the advantages of pole over Breit-Wigner parameters in quantifying scattering matrix resonant states are becoming indisputable, we supplement the original solution with the pole parameters. Because of an already reported numeric error in the S11 analytic continuation [Batinić , Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.57.1004 57, 1004(E) (1997); arXiv:nucl-th/9703023], we declare the old BATINIC 95 solution, presently included by the PDG, invalid. Instead, we offer two new solutions: (A) corrected BATINIC 95 and (B) a new solution with an improved S11 πN elastic input. We endorse solution (B).

Neutron Scattering Cross Section Measurements for 169Tm via the (n,n') Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alimeti, Afrim; Kegel, Gunter H.R.; Egan, James J.

2005-05-24

The neutron physics group at the University of Massachusetts Lowell (UML) has been involved in a program of scattering cross-section measurements for highly deformed nuclei such as 159Tb, 169Tm, 232Th, 235U, 238U, and 239Pu. Ko et al. have reported neutron inelastic scattering data from 169Tm for states above 100 keV via the (n,n'{gamma}) reaction at incident energies in the 0.2 MeV to 1.0 MeV range. In the present research, in which the time-of-flight method was employed, direct (n,n') measurements of neutrons scattered from 169Tm in the 0.2 to 1.0 MeV range were taken. It requires that our 5.5-MeV Van demore » Graaff accelerator be operated in the pulsed and bunched beam mode producing subnanosecond pulses at a 5-MHz repetition frequency. Neutrons are produced by the 7Li(p,n)7Be reaction using a thin metallic elemental lithium target.« less

Communication Optimal Parallel Multiplication of Sparse Random Matrices

DTIC Science & Technology

2013-02-21

Definition 2.1), and (2) the algorithm is sparsity- independent, where the computation is statically partitioned to processors independent of the sparsity...struc- ture of the input matrices (see Definition 2.5). The second assumption applies to nearly all existing al- gorithms for general sparse matrix-matrix...where A and B are n× n ER(d) matrices: Definition 2.1 An ER(d) matrix is an adjacency matrix of an Erdős-Rényi graph with parameters n and d/n. That

Method and apparatus for detecting and/or imaging clusters of small scattering centers in the body

DOEpatents

Perez-Mendez, V.; Sommer, F.G.

1982-07-13

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.

Method and apparatus for detecting and/or imaging clusters of small scattering centers in the body

DOEpatents

Perez-Mendez, Victor; Sommer, Frank G.

1982-01-01

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.

Fast method to compute scattering by a buried object under a randomly rough surface: PILE combined with FB-SA.

PubMed

Bourlier, Christophe; Kubické, Gildas; Déchamps, Nicolas

2008-04-01

A fast, exact numerical method based on the method of moments (MM) is developed to calculate the scattering from an object below a randomly rough surface. Déchamps et al. [J. Opt. Soc. Am. A23, 359 (2006)] have recently developed the PILE (propagation-inside-layer expansion) method for a stack of two one-dimensional rough interfaces separating homogeneous media. From the inversion of the impedance matrix by block (in which two impedance matrices of each interface and two coupling matrices are involved), this method allows one to calculate separately and exactly the multiple-scattering contributions inside the layer in which the inverses of the impedance matrices of each interface are involved. Our purpose here is to apply this method for an object below a rough surface. In addition, to invert a matrix of large size, the forward-backward spectral acceleration (FB-SA) approach of complexity O(N) (N is the number of unknowns on the interface) proposed by Chou and Johnson [Radio Sci.33, 1277 (1998)] is applied. The new method, PILE combined with FB-SA, is tested on perfectly conducting circular and elliptic cylinders located below a dielectric rough interface obeying a Gaussian process with Gaussian and exponential height autocorrelation functions.

In Situ Evaluation of Calcium Phosphate Nucleation Kinetics and Pathways during Intra- and Extrafibrillar Mineralization of Collagen Matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Doyoon; Lee, Byeongdu; Thomopoulos, Stavros

Calcium phosphate (CaP) nanocrystals nucleate and grow in intrafibrillar and/or extrafibrillar spaces of collagen fibrils during the mineralization of bones and teeth. Little is known about the early stages of CaP nucleation and distribution in fibrillar matrices, despite their significant influence on the physical and chemical structures of tissue-level constructs. Using in situ small angle X-ray scattering (SAXS), we examined the nucleation and growth of CaP within collagen matrices and elucidated how a nucleation inhibitor, polyaspartic acid (pAsp), governs mineralization kinetics and pathways at multiple length scales. In situ SAXS analysis clearly revealed that nucleation sites, kinetically-controlled by the nucleationmore » inhibitor, determined the pathways of CaP morphological transformation. Mineralization with pAsp led to intrafibrillar CaP plates with a spatial distribution gradient through the depth of the matrix. Mineralization without pAsp led initially to spherical aggregates of CaP in the entire extrafibrillar spaces. With time, the spherical aggregates transformed into plates at the outermost surface of the collagen matrix, preventing intrafibrillar mineralization inside. The results illuminate mineral nucleation kinetics and real-time nanoparticle distributions within organic matrices in solutions containing body fluid components. Because the macroscale mechanical properties of collagen matrices depend on their mineral content, phase, and arrangement at the nanoscale, this study contributes to better design and fabrication of biomaterials for regenerative medicine.« less

Reduction theorems for optimal unambiguous state discrimination of density matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raynal, Philippe; Luetkenhaus, Norbert; Enk, Steven J. van

2003-08-01

We present reduction theorems for the problem of optimal unambiguous state discrimination of two general density matrices. We show that this problem can be reduced to that of two density matrices that have the same rank n and are described in a Hilbert space of dimensions 2n. We also show how to use the reduction theorems to discriminate unambiguously between N mixed states (N{>=}2)

Mixed quantum/classical theory for inelastic scattering of asymmetric-top-rotor + atom in the body-fixed reference frame and application to the H₂O + He system.

PubMed

Semenov, Alexander; Dubernet, Marie-Lise; Babikov, Dmitri

2014-09-21

The mixed quantum/classical theory (MQCT) for inelastic molecule-atom scattering developed recently [A. Semenov and D. Babikov, J. Chem. Phys. 139, 174108 (2013)] is extended to treat a general case of an asymmetric-top-rotor molecule in the body-fixed reference frame. This complements a similar theory formulated in the space-fixed reference-frame [M. Ivanov, M.-L. Dubernet, and D. Babikov, J. Chem. Phys. 140, 134301 (2014)]. Here, the goal was to develop an approximate computationally affordable treatment of the rotationally inelastic scattering and apply it to H2O + He. We found that MQCT is somewhat less accurate at lower scattering energies. For example, below E = 1000 cm(-1) the typical errors in the values of inelastic scattering cross sections are on the order of 10%. However, at higher scattering energies MQCT method appears to be rather accurate. Thus, at scattering energies above 2000 cm(-1) the errors are consistently in the range of 1%-2%, which is basically our convergence criterion with respect to the number of trajectories. At these conditions our MQCT method remains computationally affordable. We found that computational cost of the fully-coupled MQCT calculations scales as n(2), where n is the number of channels. This is more favorable than the full-quantum inelastic scattering calculations that scale as n(3). Our conclusion is that for complex systems (heavy collision partners with many internal states) and at higher scattering energies MQCT may offer significant computational advantages.

Quasifree (p ,p N ) scattering of light neutron-rich nuclei near N =14

NASA Astrophysics Data System (ADS)

Díaz Fernández, P.; Alvarez-Pol, H.; Crespo, R.; Cravo, E.; Atar, L.; Deltuva, A.; Aumann, T.; Avdeichikov, V.; Beceiro-Novo, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Boillos, J. M.; Boretzky, K.; Borge, M. J. G.; Caamaño, M.; Cabanelas, P.; Caesar, C.; Casarejos, E.; Catford, W.; Cederkäll, J.; Chartier, M.; Chulkov, L. V.; Cortina-Gil, D.; Datta Pramanik, U.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estradé, A.; Farinon, F.; Fernández-Domínguez, B.; Fraile, L. M.; Freer, M.; Galaviz, D.; Geissel, H.; Gernhäuser, R.; Golubev, P.; Göbel, K.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Heinz, A.; Henriques, A.; Holl, M.; Hufnagel, A.; Ignatov, A.; Johansson, H. T.; Jonson, B.; Jurčiukonis, D.; Kalantar-Nayestanaki, N.; Kanungo, R.; Kelic-Heil, A.; Knyazev, A.; Kröll, T.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lindberg, S.; Machado, J.; Marganiec, J.; Moro, A. M.; Movsesyan, A.; Nacher, E.; Najafi, A.; Nikolskii, E.; Nilsson, T.; Nociforo, C.; Panin, V.; Paschalis, S.; Perea, A.; Petri, M.; Pietras, B.; Pietri, S.; Plag, R.; Reifarth, R.; Ribeiro, G.; Rigollet, C.; Rossi, D.; Röder, M.; Savran, D.; Scheit, H.; Simon, H.; Sorlin, O.; Syndikus, I.; Taylor, J. T.; Tengblad, O.; Thies, R.; Togano, Y.; Vandebrouck, M.; Velho, P.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Wheldon, C.; Wilson, G.; Winfield, J. S.; Woods, P.; Yakorev, D.; Zhukov, M.; Zilges, A.; Zuber, K.; R³B Collaboration

2018-02-01

Background: For many years, quasifree scattering reactions in direct kinematics have been extensively used to study the structure of stable nuclei, demonstrating the potential of this approach. The R 3B collaboration has performed a pilot experiment to study quasifree scattering reactions in inverse kinematics for a stable 12C beam. The results from that experiment constitute the first quasifree scattering results in inverse and complete kinematics. This technique has lately been extended to exotic beams to investigate the evolution of shell structure, which has attracted much interest due to changes in shell structure if the number of protons or neutrons is varied. Purpose: In this work we investigate for the first time the quasifree scattering reactions (p ,p n ) and (p ,2 p ) simultaneously for the same projectile in inverse and complete kinematics for radioactive beams with the aim to study the evolution of single-particle properties from N =14 to N =15 . Method: The structure of the projectiles 23O, 22O, and 21N has been studied simultaneously via (p ,p n ) and (p ,2 p ) quasifree knockout reactions in complete inverse kinematics, allowing the investigation of proton and neutron structure at the same time. The experimental data were collected at the R3B -LAND setup at GSI at beam energies of around 400 MeV/u. Two key observables have been studied to shed light on the structure of those nuclei: the inclusive cross sections and the corresponding momentum distributions. Conclusions: The knockout reactions (p ,p n ) and (p ,2 p ) with radioactive beams in inverse kinematics have provided important and complementary information for the study of shell evolution and structure. For the (p ,p n ) channels, indications of a change in the structure of these nuclei moving from N =14 to N =15 have been observed, i.e., from the 0 d5 /2 shell to the 1 s1 /2 . This supports previous observations of a subshell closure at N =14 for neutron-rich oxygen isotopes and its weakening

Online analysis of protein inclusion bodies produced in E. coli by monitoring alterations in scattered and reflected light.

PubMed

Ude, Christian; Ben-Dov, Nadav; Jochums, André; Li, Zhaopeng; Segal, Ester; Scheper, Thomas; Beutel, Sascha

2016-05-01

The online monitoring of recombinant protein aggregate inclusion bodies during microbial cultivation is an immense challenge. Measurement of scattered and reflected light offers a versatile and non-invasive measurement technique. Therefore, we investigated two methods to detect the formation of inclusion bodies and monitor their production: (1) online 180° scattered light measurement (λ = 625 nm) using a sensor platform during cultivation in shake flask and (2) online measurement of the light reflective interference using a porous Si-based optical biosensor (SiPA). It could be shown that 180° scattered light measurement allows monitoring of alterations in the optical properties of Escherichia coli BL21 cells, associated with the formation of inclusion bodies during cultivation. A reproducible linear correlation between the inclusion body concentration of the non-fluorescent protein human leukemia inhibitory factor (hLIF) carrying a thioredoxin tag and the shift ("Δamp") in scattered light signal intensity was observed. This was also observed for the glutathione-S-transferase-tagged green fluorescent protein (GFP-GST). Continuous online monitoring of reflective interference spectra reveals a significant increase in the bacterium refractive index during hLIF production in comparison to a non-induced reference that coincide with the formation of inclusion bodies. These online monitoring techniques could be applied for fast and cost-effective screening of different protein expression systems.

Search For Anomalous n-p Scattering At 60 eV-140 keV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreh, R.; Block, R. C.; Danon, Y.

2009-01-28

A search for an anomalous n-p scattering from a polyethylene sample (CH{sub 2}) at 8 final energies between 64 eV and 2.5 keV was carried out. The scattering intensities were compared to that from a graphite (C) sample. The results were found to confirm our previous n-p results on H{sub 2}O at a final energy of 24.3 keV where no n-p scattering anomaly was observed. The present results refute all proposed models attempting to explain the occurrence of any n-p scattering anomaly at keV neutron energies.

Scattering matrix elements of biological particles measured in a flow through system: theory and practice.

PubMed

Sloot, P M; Hoekstra, A G; van der Liet, H; Figdor, C G

1989-05-15

Light scattering techniques (including depolarization experiments) applied to biological cells provide a fast nondestructive probe that is very sensitive to small morphological differences. Until now quantitative measurement of these scatter phenomena were only described for particles in suspension. In this paper we discuss the symmetry conditions applicable to the scattering matrices of monodisperse biological cells in a flow cytometer and provide evidence that quantitative measurement of the elements of these scattering matrices is possible in flow through systems. Two fundamental extensions to the theoretical description of conventional scattering experiments are introduced: large cone integration of scattering signals and simultaneous implementation of the localization principle to account for scattering by a sharply focused laser beam. In addition, a specific calibration technique is proposed to account for depolarization effects of the highly specialized optics applied in flow through equipment.

Radiation and scattering from bodies of translation, volume 1

NASA Astrophysics Data System (ADS)

Medgyesi-Mitschang, L. N.

1980-04-01

An analytical formulation, based on the method of moments (MM) is described for solving electromagnetic problems associated with finite-length cylinders of arbitrary cross section, denoted in this report as bodies of translation (BOT). This class of bodies can be used to model structures with noncircular cross sections such as wings, fins, and aircraft fuselages. The theoretical development parallels in part the MM formulation developed earlier by Mautz and Harrington for bodies of revolution (BOR). Like the latter approach, a modal expansion is used to describe the unknown surface currents on the BOT. The present analysis has been developed to treat the far-field radiation and scattering from a BOT excited by active antennas or illuminated by a plane wave of arbitrary polarization and angle of incidence. In addition, the electric and magnetic near-field components are determined in the vicinity of active and passive apertures (slots). Using the Schelkunoff equivalence theorem, the aperture-coupled fields within a BOT are also obtained. The formulation has been implemented by a computer algorithm and validated using accepted data in the literature.

Periodic GMP Matrices

NASA Astrophysics Data System (ADS)

Eichinger, Benjamin

2016-07-01

We recall criteria on the spectrum of Jacobi matrices such that the corresponding isospectral torus consists of periodic operators. Motivated by those known results for Jacobi matrices, we define a new class of operators called GMP matrices. They form a certain Generalization of matrices related to the strong Moment Problem. This class allows us to give a parametrization of almost periodic finite gap Jacobi matrices by periodic GMP matrices. Moreover, due to their structural similarity we can carry over numerous results from the direct and inverse spectral theory of periodic Jacobi matrices to the class of periodic GMP matrices. In particular, we prove an analogue of the remarkable ''magic formula'' for this new class.

Making almost commuting matrices commute

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hastings, Matthew B

Suppose two Hermitian matrices A, B almost commute ({parallel}[A,B]{parallel} {<=} {delta}). Are they close to a commuting pair of Hermitian matrices, A', B', with {parallel}A-A'{parallel},{parallel}B-B'{parallel} {<=} {epsilon}? A theorem of H. Lin shows that this is uniformly true, in that for every {epsilon} > 0 there exists a {delta} > 0, independent of the size N of the matrices, for which almost commuting implies being close to a commuting pair. However, this theorem does not specifiy how {delta} depends on {epsilon}. We give uniform bounds relating {delta} and {epsilon}. The proof is constructive, giving an explicit algorithm to construct A'more » and B'. We provide tighter bounds in the case of block tridiagonal and tridiagnonal matrices. Within the context of quantum measurement, this implies an algorithm to construct a basis in which we can make a projective measurement that approximately measures two approximately commuting operators simultaneously. Finally, we comment briefly on the case of approximately measuring three or more approximately commuting operators using POVMs (positive operator-valued measures) instead of projective measurements.« less

Harmonic oscillator representation in the theory of scattering and nuclear reactions

NASA Technical Reports Server (NTRS)

Smirnov, Yuri F.; Shirokov, A. M.; Lurie, Yuri, A.; Zaitsev, S. A.

1995-01-01

The following questions, concerning the application of the harmonic oscillator representation (HOR) in the theory of scattering and reactions, are discussed: the formulation of the scattering theory in HOR; exact solutions of the free motion Schroedinger equation in HOR; separable expansion of the short range potentials and the calculation of the phase shifts; 'isolated states' as generalization of the Wigner-von Neumann bound states embedded in continuum; a nuclear coupled channel problem in HOR; and the description of true three body scattering in HOR. As an illustration the soft dipole mode in the (11)Li nucleus is considered in a frame of the (9)Li+n+n cluster model taking into account of three body continuum effects.

Proton-Nucleus Elastic Cross Sections Using Two-Body In-Medium Scattering Amplitudes

NASA Technical Reports Server (NTRS)

Tripathi, R. K.; Wilson, John W.; Cucinotta, Francis A.

2001-01-01

Recently, a method was developed of extracting nucleon-nucleon (NN) cross sections in the medium directly from experiment. The in-medium NN cross sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the Langley Research Center. The ratio of the real to the imaginary part of the two-body scattering amplitude in the medium was investigated. These ratios are used in combination with the in-medium NN cross sections to calculate elastic proton-nucleus cross sections. The agreement is excellent with the available experimental data. These cross sections are needed for the radiation risk assessment of space missions.

9Be+120Sn scattering at near-barrier energies within a four-body model

NASA Astrophysics Data System (ADS)

Arazi, A.; Casal, J.; Rodríguez-Gallardo, M.; Arias, J. M.; Lichtenthäler Filho, R.; Abriola, D.; Capurro, O. A.; Cardona, M. A.; Carnelli, P. F. F.; de Barbará, E.; Fernández Niello, J.; Figueira, J. M.; Fimiani, L.; Hojman, D.; Martí, G. V.; Martínez Heimman, D.; Pacheco, A. J.

2018-04-01

Cross sections for elastic and inelastic scattering of the weakly bound 9Be nucleus on a 120Sn target have been measured at seven bombarding energies around and above the Coulomb barrier. The elastic angular distributions are analyzed with a four-body continuum-discretized coupled-channels (CDCC) calculation, which considers 9Be as a three-body projectile (α +α +n ). An optical model analysis using the São Paulo potential is also shown for comparison. The CDCC analysis shows that the coupling to the continuum part of the spectrum is important for the agreement with experimental data even at energies around the Coulomb barrier, suggesting that breakup is an important process at low energies. At the highest incident energies, two inelastic peaks are observed at 1.19(5) and 2.41(5) MeV. Coupled-channels (CC) calculations using a rotational model confirm that the first inelastic peak corresponds to the excitation of the 21+ state in 120Sn, while the second one likely corresponds to the excitation of the 31- state.

Closed-loop multiple-scattering imaging with sparse seismic measurements

NASA Astrophysics Data System (ADS)

Berkhout, A. J. Guus

2018-03-01

In the theoretical situation of noise-free, complete data volumes (`perfect data'), seismic data matrices are fully filled and multiple-scattering operators have the minimum-phase property. Perfect data allow direct inversion methods to be successful in removing surface and internal multiple scattering. Moreover, under these perfect data conditions direct source wavefields realize complete illumination (no irrecoverable shadow zones) and, therefore, primary reflections (first-order response) can provide us with the complete seismic image. However, in practice seismic measurements always contain noise and we never have complete data volumes at our disposal. We actually deal with sparse data matrices that cannot be directly inverted. The message of this paper is that in practice multiple scattering (including source ghosting) must not be removed but must be utilized. It is explained that in the real world we badly need multiple scattering to fill the illumination gaps in the subsurface. It is also explained that the proposed multiple-scattering imaging algorithm gives us the opportunity to decompose both the image and the wavefields into order-based constituents, making the multiple scattering extension easy to apply. Last but not least, the algorithm allows us to use the minimum-phase property to validate and improve images in an objective way.

Effect of repulsive and attractive three-body forces on nucleus-nucleus elastic scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furumoto, T.; Sakuragi, Y.; Yamamoto, Y.

2009-10-15

The effect of the three-body force (TBF) is studied in nucleus-nucleus elastic scattering on the basis of Brueckner theory for nucleon-nucleon (NN) effective interaction (complex G matrix) in the nuclear matter. A new G matrix called CEG07 proposed recently by the present authors includes the TBF effect and reproduces a realistic saturation curve in the nuclear matter, and it is shown to well reproduce proton-nucleus elastic scattering. The microscopic optical potential for the nucleus-nucleus system is obtained by folding the G matrix with nucleon density distributions in colliding nuclei. We first analyze in detail the {sup 16}O+{sup 16}O elastic scatteringmore » at E/A=70 MeV. The observed cross sections are nicely reproduced up to the most backward scattering angles only when the TBF effect is included. The use of the frozen-density approximation (FDA) is essentially important to properly estimate the effect of the TBF in nucleus-nucleus scattering. Other prescriptions for defining the local density have also been tested, but only the FDA prescription gives a proper description of the experimental cross sections as well as the effect of the TBF. The effects of the three-body attraction and the {omega}-rearrangement term are also analyzed. The CEG07 interaction is compared with CDM3Y6, which is a reliable and successful effective density-dependent NN interaction used in the double-folding model. The CEG07 G matrix is also tested in the elastic scattering of {sup 16}O by the {sup 12}C, {sup 28}Si, and {sup 40}Ca targets at E/A=93.9 MeV, and in the elastic scattering of {sup 12}C by the {sup 12}C target at E/A=135 MeV with great success. The decisive effect of the TBF is clearly seen also in those systems. Finally, we have tested CEG07a, CEG07b, and CEG07c for the {sup 16}O+{sup 16}O system at various energies.« less

On Fluctuations of Eigenvalues of Random Band Matrices

NASA Astrophysics Data System (ADS)

Shcherbina, M.

2015-10-01

We consider the fluctuations of linear eigenvalue statistics of random band matrices whose entries have the form with i.i.d. possessing the th moment, where the function u has a finite support , so that M has only nonzero diagonals. The parameter b (called the bandwidth) is assumed to grow with n in a way such that . Without any additional assumptions on the growth of b we prove CLT for linear eigenvalue statistics for a rather wide class of test functions. Thus we improve and generalize the results of the previous papers (Jana et al., arXiv:1412.2445; Li et al. Random Matrices 2:04, 2013), where CLT was proven under the assumption . Moreover, we develop a method which allows to prove automatically the CLT for linear eigenvalue statistics of the smooth test functions for almost all classical models of random matrix theory: deformed Wigner and sample covariance matrices, sparse matrices, diluted random matrices, matrices with heavy tales etc.

Efimov effect for heteronuclear three-body systems at positive scattering length and finite temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2017-09-08

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

Energy spectra of small bosonic clusters having a large two-body scattering length

NASA Astrophysics Data System (ADS)

Gattobigio, M.; Kievsky, A.; Viviani, M.

2012-10-01

In this work we investigate small clusters of bosons using the hyperspherical harmonic basis. We consider systems with A=2,3,4,5,6 particles interacting through a soft interparticle potential. In order to make contact with a real system, we use an attractive Gaussian potential that reproduces the values of the dimer binding energy and the atom-atom scattering length obtained with one of the most widely used 4He-4He interactions, the LM2M2 potential of Aziz and Slaman. The intensity of the potential is varied in order to explore the clusters’ spectra in different regions with large positive and large negative values of the two-body scattering length. In addition, we include a repulsive three-body force to reproduce the trimer binding energy. With this model, consisting in the sum of a two- and three-body potential, we have calculated the spectrum of the four-, five-, and six-particle systems. In all the regions explored, we have found that these systems present two states, one deep and one shallow close to the A-1 threshold. Some universal relations between the energy levels are extracted; in particular, we have estimated the universal ratios between thresholds of the three-, four-, and five-particle continua using the two-body Gaussian potential. They agree with recent measurements and theoretical predictions.

On the Wigner law in dilute random matrices

NASA Astrophysics Data System (ADS)

Khorunzhy, A.; Rodgers, G. J.

1998-12-01

We consider ensembles of N × N symmetric matrices whose entries are weakly dependent random variables. We show that random dilution can change the limiting eigenvalue distribution of such matrices. We prove that under general and natural conditions the normalised eigenvalue counting function coincides with the semicircle (Wigner) distribution in the limit N → ∞. This can be explained by the observation that dilution (or more generally, random modulation) eliminates the weak dependence (or correlations) between random matrix entries. It also supports our earlier conjecture that the Wigner distribution is stable to random dilution and modulation.

Avatar body dimensions and men's body image.

PubMed

Cacioli, Jon-Paul; Mussap, Alexander J

2014-03-01

Two online surveys examined the significance of the visual analogues, or 'avatars', men (total N=266) create and use online. Two-dimensional (adiposity×muscle) somatomorphic matrices revealed that avatars are generally thinner than their creator's actual body and similar to their ideal, but more muscular than either their actual or ideal. Men's ratings of the importance of their avatar's appearance correlated with their actual weight and muscle concerns, and disparity between their avatar and actual body dimensions predicted their offline context body change concerns additional to that accounted for by disparity between their ideal and actual bodies. Together with the observation that men also reported higher self-esteem, less social interaction anxiety and less social phobia while online (which correlated with the time they spent online), these results suggest that the physical dimensions of avatars used in social interactions online may serve a compensatory function. Copyright © 2013 Elsevier Ltd. All rights reserved.

A boundary integral approach to the scattering of nonplanar acoustic waves by rigid bodies

NASA Technical Reports Server (NTRS)

Gallman, Judith M.; Myers, M. K.; Farassat, F.

1990-01-01

The acoustic scattering of an incident wave by a rigid body can be described by a singular Fredholm integral equation of the second kind. This equation is derived by solving the wave equation using generalized function theory, Green's function for the wave equation in unbounded space, and the acoustic boundary condition for a perfectly rigid body. This paper will discuss the derivation of the wave equation, its reformulation as a boundary integral equation, and the solution of the integral equation by the Galerkin method. The accuracy of the Galerkin method can be assessed by applying the technique outlined in the paper to reproduce the known pressure fields that are due to various point sources. From the analysis of these simpler cases, the accuracy of the Galerkin solution can be inferred for the scattered pressure field caused by the incidence of a dipole field on a rigid sphere. The solution by the Galerkin technique can then be applied to such problems as a dipole model of a propeller whose pressure field is incident on a rigid cylinder. This is the groundwork for modeling the scattering of rotating blade noise by airplane fuselages.

Quantum Entanglement and Reduced Density Matrices

NASA Astrophysics Data System (ADS)

Purwanto, Agus; Sukamto, Heru; Yuwana, Lila

2018-05-01

We investigate entanglement and separability criteria of multipartite (n-partite) state by examining ranks of its reduced density matrices. Firstly, we construct the general formula to determine the criterion. A rank of origin density matrix always equals one, meanwhile ranks of reduced matrices have various ranks. Next, separability and entanglement criterion of multipartite is determined by calculating ranks of reduced density matrices. In this article we diversify multipartite state criteria into completely entangled state, completely separable state, and compound state, i.e. sub-entangled state and sub-entangledseparable state. Furthermore, we also shorten the calculation proposed by the previous research to determine separability of multipartite state and expand the methods to be able to differ multipartite state based on criteria above.

Hydrodynamic outcomes of planet scattering in transitional discs

NASA Astrophysics Data System (ADS)

Moeckel, Nickolas; Armitage, Philip J.

2012-01-01

A significant fraction of unstable multiple planet systems are likely to scatter during the transitional disc phase as gas damping becomes ineffectual. Using a large ensemble of FARGO hydrodynamic simulations and MERCURY N-body integrations, we directly follow the dynamics of planet-disc and planet-planet interactions through the clearing phase and through 50 Myr of planetary system evolution. Disc clearing is assumed to occur as a result of X-ray-driven photoevaporation. We find that the hydrodynamic evolution of individual scattering systems is complex, and can involve phases in which massive planets orbit within eccentric gaps, or accrete directly from the disc without a gap. Comparing the results to a reference gas-free model, we find that the N-body dynamics and hydrodynamics of scattering into one- and two-planet final states are almost identical. The eccentricity distributions in these channels are almost unaltered by the presence of gas. The hydrodynamic simulations, however, also form a population of low-eccentricity three-planet systems in long-term stable configurations, which are not found in N-body runs. The admixture of these systems results in modestly lower eccentricities in hydrodynamic as opposed to gas-free simulations. The precise incidence of these three-planet systems is likely a function of the initial conditions; different planet set-ups (number or spacing) may change the quantitative character of this result. We analyse the properties of surviving multiple planet systems, and show that only a small fraction (a few per cent) enter mean motion resonances after scattering, while a larger fraction form stable resonant chains and avoid scattering entirely. Our results remain consistent with the hypothesis that exoplanet eccentricity results from scattering, though the detailed agreement between observations and gas-free simulation results is likely coincidental. We discuss the prospects for further tests of scattering models by observing planets

The role of polarization coulomb field scattering in the electron mobility of AlGaN/AlN/GaN heterostructure field-effect transistors

NASA Astrophysics Data System (ADS)

Liu, Yan; Lin, Zhaojun; Zhao, Jingtao; Yang, Ming; Shi, Wenjing; Lv, Yuanjie; Feng, Zhihong

2016-04-01

The electron mobility for the prepared AlGaN/AlN/GaN heterostructure field-effect transistor (HFET) with the ratio of the gate length to the drain-to-source distance being less than 1/2 has been studied by comparing the measured electron mobility with the theoretical value. The measured electron mobility is derived from the measured capacitance-voltage (C-V) and current-voltage (I-V) characteristics, and the theoretical mobility is determined by using Matthiessen's law, involving six kinds of important scattering mechanisms. For the prepared device at room temperature, longitudinal optical phonon scattering (LO scattering) was found to have a remarkable effect on the value of the electron mobility, and polarization Coulomb field scattering (PCF scattering ) was found to be important to the changing trend of the electron mobility versus the two-dimensional electron gas (2DEG) density.

Roy-Steiner equations for πN scattering

NASA Astrophysics Data System (ADS)

Ruiz de Elvira, J.; Ditsche, C.; Hoferichter, M.; Kubis, B.; Meißner, U.-G.

2014-06-01

In this talk, we present a coupled system of integral equations for the πN → πN (s-channel) and ππ → N̅N (t-channel) lowest partial waves, derived from Roy-Steiner equations for pion-nucleon scattering. After giving a brief overview of this system of equations, we present the solution of the t-channel sub-problem by means of Muskhelishvili-Omnès techniques, and solve the s-channel sub-problem after finding a set of phase shifts and subthreshold parameters which satisfy the Roy-Steiner equations.

Hurwitz numbers and products of random matrices

NASA Astrophysics Data System (ADS)

Orlov, A. Yu.

2017-09-01

We study multimatrix models, which may be viewed as integrals of products of tau functions depending on the eigenvalues of products of random matrices. We consider tau functions of the two-component Kadomtsev-Petviashvili (KP) hierarchy (semi-infinite relativistic Toda lattice) and of the B-type KP (BKP) hierarchy introduced by Kac and van de Leur. Such integrals are sometimes tau functions themselves. We consider models that generate Hurwitz numbers HE,F, where E is the Euler characteristic of the base surface and F is the number of branch points. We show that in the case where the integrands contain the product of n > 2 matrices, the integral generates Hurwitz numbers with E ≤ 2 and F ≤ n+2. Both the numbers E and F depend both on n and on the order of the factors in the matrix product. The Euler characteristic E can be either an even or an odd number, i.e., it can match both orientable and nonorientable (Klein) base surfaces depending on the presence of the tau function of the BKP hierarchy in the integrand. We study two cases, the products of complex and the products of unitary matrices.

Spectral density of mixtures of random density matrices for qubits

NASA Astrophysics Data System (ADS)

Zhang, Lin; Wang, Jiamei; Chen, Zhihua

2018-06-01

We derive the spectral density of the equiprobable mixture of two random density matrices of a two-level quantum system. We also work out the spectral density of mixture under the so-called quantum addition rule. We use the spectral densities to calculate the average entropy of mixtures of random density matrices, and show that the average entropy of the arithmetic-mean-state of n qubit density matrices randomly chosen from the Hilbert-Schmidt ensemble is never decreasing with the number n. We also get the exact value of the average squared fidelity. Some conjectures and open problems related to von Neumann entropy are also proposed.

Measurement of Off-Body Velocity, Pressure, and Temperature in an Unseeded Supersonic Air Vortex by Stimulated Raman Scattering

NASA Technical Reports Server (NTRS)

Herring, Gregory C.

2008-01-01

A noninvasive optical method is used to make time-averaged (30 sec) off-body measurements in a supersonic airflow. Seeding of tracer particles is not required. One spatial component of velocity, static pressure, and static temperature are measured with stimulated Raman scattering. The three flow parameters are determined simultaneously from a common sample volume (0.3 by 0.3 by 15 mm) using concurrent measurements of the forward and backward scattered line shapes of a N2 vibrational Raman transition. The capability of this technique is illustrated with laboratory and large-scale wind tunnel testing that demonstrate 5-10% measurement uncertainties. Because the spatial resolution of the present work was improved to 1.5 cm (compared to 20 cm in previous work), it was possible to demonstrate a modest one-dimensional profiling of cross-flow velocity, pressure, and translational temperature through the low-density core of a stream-wise vortex (delta-wing model at Mach 2.8 in NASA Langley's Unitary Plan Wind Tunnel).

Raman scattering from TO phonons in (GaAs)n/(AlAs)n superlattices

NASA Astrophysics Data System (ADS)

Wang, Z. P.; Han, H. X.; Li, G. H.; Jiang, D. S.; Ploog, K.

1988-10-01

(GaAS)n/(AlAs)n superlattices with n=4, 6, and 8 grown by molecular-beam epitaxy on (001)-oriented GaAs substrates were investigated by Raman scattering. In a strict backscattering geometry, confined TO-phonon modes with E symmetry are Raman forbidden. However, the effects due to near-Brewster-angle incidence and a large aperture of the scattering-light collecting lens create a small wave-vector component along the (110) orientation, and thus induce a Raman activity of TO phonons. When we take X∥[11¯0], Y∥[110], and Z∥[001], in the near-Z(YX)Z¯ backscattering configuration confined LO-phonon modes are Raman inactive. Using this configuration, we have for the first time observed both GaAs-like and AlAs-like confined TO-phonon modes at room temperature and under off-resonance conditions.

Migration of scattered teleseismic body waves

NASA Astrophysics Data System (ADS)

Bostock, M. G.; Rondenay, S.

1999-06-01

The retrieval of near-receiver mantle structure from scattered waves associated with teleseismic P and S and recorded on three-component, linear seismic arrays is considered in the context of inverse scattering theory. A Ray + Born formulation is proposed which admits linearization of the forward problem and economy in the computation of the elastic wave Green's function. The high-frequency approximation further simplifies the problem by enabling (1) the use of an earth-flattened, 1-D reference model, (2) a reduction in computations to 2-D through the assumption of 2.5-D experimental geometry, and (3) band-diagonalization of the Hessian matrix in the inverse formulation. The final expressions are in a form reminiscent of the classical diffraction stack of seismic migration. Implementation of this procedure demands an accurate estimate of the scattered wave contribution to the impulse response, and thus requires the removal of both the reference wavefield and the source time signature from the raw record sections. An approximate separation of direct and scattered waves is achieved through application of the inverse free-surface transfer operator to individual station records and a Karhunen-Loeve transform to the resulting record sections. This procedure takes the full displacement field to a wave vector space wherein the first principal component of the incident wave-type section is identified with the direct wave and is used as an estimate of the source time function. The scattered displacement field is reconstituted from the remaining principal components using the forward free-surface transfer operator, and may be reduced to a scattering impulse response upon deconvolution of the source estimate. An example employing pseudo-spectral synthetic seismograms demonstrates an application of the methodology.

Basal Cell Carcinoma With Matrical Differentiation: Clinicopathologic, Immunohistochemical, and Molecular Biological Study of 22 Cases.

PubMed

Kyrpychova, Liubov; Carr, Richard A; Martinek, Petr; Vanecek, Tomas; Perret, Raul; Chottová-Dvořáková, Magdalena; Zamecnik, Michal; Hadravsky, Ladislav; Michal, Michal; Kazakov, Dmitry V

2017-06-01

Basal cell carcinoma (BCC) with matrical differentiation is a fairly rare neoplasm, with about 30 cases documented mainly as isolated case reports. We studied a series of this neoplasm, including cases with an atypical matrical component, a hitherto unreported feature. Lesions coded as BCC with matrical differentiation were reviewed; 22 cases were included. Immunohistochemical studies were performed using antibodies against BerEp4, β-catenin, and epithelial membrane antigen (EMA). Molecular genetic studies using Ion AmpliSeq Cancer Hotspot Panel v2 by massively parallel sequencing on Ion Torrent PGM were performed in 2 cases with an atypical matrical component (1 was previously subjected to microdissection to sample the matrical and BCC areas separately). There were 13 male and 9 female patients, ranging in age from 41 to 89 years. Microscopically, all lesions manifested at least 2 components, a BCC area (follicular germinative differentiation) and areas with matrical differentiation. A BCC component dominated in 14 cases, whereas a matrical component dominated in 4 cases. Matrical differentiation was recognized as matrical/supramatrical cells (n=21), shadow cells (n=21), bright red trichohyaline granules (n=18), and blue-gray corneocytes (n=18). In 2 cases, matrical areas manifested cytologic atypia, and a third case exhibited an infiltrative growth pattern, with the tumor metastasizing to a lymph node. BerEP4 labeled the follicular germinative cells, whereas it was markedly reduced or negative in matrical areas. The reverse pattern was seen with β-catenin. EMA was negative in BCC areas but stained a proportion of matrical/supramatrical cells. Genetic studies revealed mutations of the following genes: CTNNB1, KIT, CDKN2A, TP53, SMAD4, ERBB4, and PTCH1, with some differences between the matrical and BCC components. It is concluded that matrical differentiation in BCC in most cases occurs as multiple foci. Rare neoplasms manifest atypia in the matrical areas

Measurement of the n-p elastic scattering angular distribution at E{sub n}=14.9 MeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boukharouba, N.; Bateman, F. B.; Carlson, A. D.

2010-07-15

The relative differential cross section for the elastic scattering of neutrons by protons was measured at an incident neutron energy E{sub n}=14.9 MeV and for center-of-mass scattering angles ranging from about 60 deg. to 180 deg. Angular distribution values were obtained from the normalization of the integrated data to the n-p total elastic scattering cross section. Comparisons of the normalized data to the predictions of the Arndt et al. phase-shift analysis, those of the Nijmegen group, and with the ENDF/B-VII.0 evaluation are sensitive to the value of the total elastic scattering cross section used to normalize the data. The resultsmore » of a fit to a first-order Legendre polynomial expansion are in good agreement in the backward scattering hemisphere with the predictions of the Arndt et al. phase-shift analysis, those of the Nijmegen group, and to a lesser extent, with the ENDF/B-VII.0 evaluation. A fit to a second-order expansion is in better agreement with the ENDF/B-VII.0 evaluation than with the other predictions, in particular when the total elastic scattering cross section given by Arndt et al. and the Nijmegen group is used to normalize the data. A Legendre polynomial fit to the existing n-p scattering data in the 14 MeV energy region, excluding the present measurement, showed that a best fit is obtained for a second-order expansion. Furthermore, the Kolmogorov-Smirnov test confirms the general agreement in the backward scattering hemisphere and shows that significant differences between the database and the predictions occur in the angular range between 60 deg. and 120 deg. and below 20 deg. Although there is good overall agreement in the backward scattering hemisphere, more precision small-angle scattering data and a better definition of the total elastic cross section are needed for an accurate determination of the shape and magnitude of the angular distribution.« less

Transformation matrices between non-linear and linear differential equations

NASA Technical Reports Server (NTRS)

Sartain, R. L.

1983-01-01

In the linearization of systems of non-linear differential equations, those systems which can be exactly transformed into the second order linear differential equation Y"-AY'-BY=0 where Y, Y', and Y" are n x 1 vectors and A and B are constant n x n matrices of real numbers were considered. The 2n x 2n matrix was used to transform the above matrix equation into the first order matrix equation X' = MX. Specially the matrix M and the conditions which will diagonalize or triangularize M were studied. Transformation matrices P and P sub -1 were used to accomplish this diagonalization or triangularization to return to the solution of the second order matrix differential equation system from the first order system.

Elastic scattering of 8He on 4He and 4 n system

NASA Astrophysics Data System (ADS)

Wolski, R.; Sidorchuk, S. I.; Ter-Akopian, G. M.; Fomichev, A. S.; Rodin, A. M.; Stepantsov, S. V.; Mittig, W.; Roussel-Chomaz, P.; Savajols, H.; Alamanos, N.; Auger, F.; Lapoux, V.; Raabe, R.; Tchuvil'sky, Yu. M.; Rusek, K.

2003-07-01

Elastic scattering of a 26A MeV beam of 8He on a gaseous helium target has been studied. In spite of efforts made for the observation of backward angle enhancement only upper limits could be obtained for the elastic scattering cross section at backward angles. The angular distribution of 8He nuclei scattered to CM 20°-80° was was analyzed in terms of a phenomenological Optical Model. Possible contributions from transfer reactions were estimated. The DWBA calculations indicate that the two step 2n transfer is more important than the one step 4n transfer. The transfer reaction d( 8He, 6Li)4n is discussed in terms of possible tests of a four-neutron system.

PoMiN: A Post-Minkowskian N-Body Solver

NASA Astrophysics Data System (ADS)

Feng, Justin; Baumann, Mark; Hall, Bryton; Doss, Joel; Spencer, Lucas; Matzner, Richard

2018-05-01

PoMiN is a lightweight N-body code based on the Post-Minkowskian N-body Hamiltonian of Ledvinka, Schafer, and Bicak, which includes General Relativistic effects up to first order in Newton's constant G, and all orders in the speed of light c. PoMiN is a single file written in C and uses a fourth-order Runge-Kutta integration scheme. PoMiN has also been written to handle an arbitrary number of particles (both massive and massless) with a computational complexity that scales as O(N^2).

Random density matrices versus random evolution of open system

NASA Astrophysics Data System (ADS)

Pineda, Carlos; Seligman, Thomas H.

2015-10-01

We present and compare two families of ensembles of random density matrices. The first, static ensemble, is obtained foliating an unbiased ensemble of density matrices. As criterion we use fixed purity as the simplest example of a useful convex function. The second, dynamic ensemble, is inspired in random matrix models for decoherence where one evolves a separable pure state with a random Hamiltonian until a given value of purity in the central system is achieved. Several families of Hamiltonians, adequate for different physical situations, are studied. We focus on a two qubit central system, and obtain exact expressions for the static case. The ensemble displays a peak around Werner-like states, modulated by nodes on the degeneracies of the density matrices. For moderate and strong interactions good agreement between the static and the dynamic ensembles is found. Even in a model where one qubit does not interact with the environment excellent agreement is found, but only if there is maximal entanglement with the interacting one. The discussion is started recalling similar considerations for scattering theory. At the end, we comment on the reach of the results for other convex functions of the density matrix, and exemplify the situation with the von Neumann entropy.

Inverse Scattering and Local Observable Algebras in Integrable Quantum Field Theories

NASA Astrophysics Data System (ADS)

Alazzawi, Sabina; Lechner, Gandalf

2017-09-01

We present a solution method for the inverse scattering problem for integrable two-dimensional relativistic quantum field theories, specified in terms of a given massive single particle spectrum and a factorizing S-matrix. An arbitrary number of massive particles transforming under an arbitrary compact global gauge group is allowed, thereby generalizing previous constructions of scalar theories. The two-particle S-matrix S is assumed to be an analytic solution of the Yang-Baxter equation with standard properties, including unitarity, TCP invariance, and crossing symmetry. Using methods from operator algebras and complex analysis, we identify sufficient criteria on S that imply the solution of the inverse scattering problem. These conditions are shown to be satisfied in particular by so-called diagonal S-matrices, but presumably also in other cases such as the O( N)-invariant nonlinear {σ}-models.

Rayleigh-Brillouin light scattering spectroscopy of nitrous oxide (N2O)

NASA Astrophysics Data System (ADS)

Wang, Y.; Liang, K.; van de Water, W.; Marques, W.; Ubachs, W.

2018-02-01

High signal-to-noise and high-resolution light scattering spectra are measured for nitrous oxide (N2O) gas at an incident wavelength of 403.00 nm, at 90° scattering, at room temperature and at gas pressures in the range 0.5 - 4 bar. The resulting Rayleigh-Brillouin light scattering spectra are compared to a number of models describing in an approximate manner the collisional dynamics and energy transfer in this gaseous medium of this polyatomic molecular species. The Tenti-S6 model, based on macroscopic gas transport coefficients, reproduces the scattering profiles in the entire pressure range at less than 2% deviation at a similar level as does the alternative kinetic Grad's 6-moment model, which is based on the internal collisional relaxation as a decisive parameter. A hydrodynamic model fails to reproduce experimental spectra for the low pressures of 0.5-1 bar, but yields very good agreement ( < 1%) in the pressure range 2 - 4 bar. While these three models have a different physical basis the internal molecular relaxation derived can for all three be described in terms of a bulk viscosity of ηb ∼(6 ± 2) ×10-5 Pa · s. A 'rough-sphere' model, previously shown to be effective to describe light scattering in SF6 gas, is not found to be suitable, likely in view of the non-sphericity and asymmetry of the N-N-O structured linear polyatomic molecule.

Compton scatter imaging: A promising modality for image guidance in lung stereotactic body radiation therapy

PubMed Central

Redler, Gage; Jones, Kevin C.; Templeton, Alistair; Bernard, Damian; Turian, Julius; Chu, James C. H.

2018-01-01

Purpose Lung stereotactic body radiation therapy (SBRT) requires delivering large radiation doses with millimeter accuracy, making image guidance essential. An approach to forming images of patient anatomy from Compton-scattered photons during lung SBRT is presented. Methods To investigate the potential of scatter imaging, a pinhole collimator and flat-panel detector are used for spatial localization and detection of photons scattered during external beam therapy using lung SBRT treatment conditions (6 MV FFF beam). MCNP Monte Carlo software is used to develop a model to simulate scatter images. This model is validated by comparing experimental and simulated phantom images. Patient scatter images are then simulated from 4DCT data. Results Experimental lung tumor phantom images have sufficient contrast-to-noise to visualize the tumor with as few as 10 MU (0.5 s temporal resolution). The relative signal intensity from objects of different composition as well as lung tumor contrast for simulated phantom images agree quantitatively with experimental images, thus validating the Monte Carlo model. Scatter images are shown to display high contrast between different materials (lung, water, bone). Simulated patient images show superior (~double) tumor contrast compared to MV transmission images. Conclusions Compton scatter imaging is a promising modality for directly imaging patient anatomy during treatment without additional radiation, and it has the potential to complement existing technologies and aid tumor tracking and lung SBRT image guidance. PMID:29360151

Computer program /P1-GAS/ calculates the P-0 and P-1 transfer matrices for neutron moderation in a monatomic gas

NASA Technical Reports Server (NTRS)

Collier, G.; Gibson, G.

1968-01-01

FORTRAN 4 program /P1-GAS/ calculates the P-O and P-1 transfer matrices for neutron moderation in a monatomic gas. The equations used are based on the conditions that there is isotropic scattering in the center-of-mass coordinate system, the scattering cross section is constant, and the target nuclear velocities satisfy a Maxwellian distribution.

Distribution of pesticides in n-hexane/water and n-hexane/acetonitrile systems and estimation of possibilities of their extraction isolation and preconcentration from various matrices.

PubMed

Zayats, M F; Leschev, S M; Petrashkevich, N V; Zayats, M A; Kadenczki, L; Szitás, R; Szemán Dobrik, H; Keresztény, N

2013-04-24

Distribution of 150 most widely used pesticides of different chemical classes (amides, anilinopirimidines, aromatics, benzenesulfonates, carbamates, dicarboximides, organophosphorus compounds, phenyl esters, phenylureas, pyrazoles, pyrethroids, pyrimidines, strobilurins, sulfamides, triazines, triazoles, etc.) in n-hexane/water and n-hexane/acetonitrile systems was investigated at 25°C. Distribution constants of pesticides (P) have been calculated as ratio of pesticide concentration in n-hexane to its concentration in water or acetonitrile phase. HPLC and GC methods were used for pesticides determination in phases. It was found that the overwhelming majority of pesticides are hydrophobic, i.e. in n-hexane/water system LgP≫0, and the difference in LgP values can reach 9.1 units. Replacement of water for acetonitrile leads to dramatic fall of LgP values reaching 9.5 units. The majority of LgP values in this case are negative and their differences is strongly leveled in comparison with a hexane/water system. Thus, maximal difference in pesticides LgP values for n-hexane/acetonitrile system is 3.2 units. It is shown that n-hexane can be used for selective and efficient extraction and preconcentration of pesticides from water matrices. On the other hand, acetonitrile is effective for the isolation and preconcentration of pesticides from hydrocarbon and vegetable oil matrices. The distribution constants described in the paper may be effectively used for the estimation of possibilities of extraction isolation, preconcentration and separation of pesticides. Copyright © 2013 Elsevier B.V. All rights reserved.

Invertible flexible matrices

NASA Astrophysics Data System (ADS)

Justino, Júlia

2017-06-01

Matrices with coefficients having uncertainties of type o (.) or O (.), called flexible matrices, are studied from the point of view of nonstandard analysis. The uncertainties of the afore-mentioned kind will be given in the form of the so-called neutrices, for instance the set of all infinitesimals. Since flexible matrices have uncertainties in their coefficients, it is not possible to define the identity matrix in an unique way and so the notion of spectral identity matrix arises. Not all nonsingular flexible matrices can be turned into a spectral identity matrix using Gauss-Jordan elimination method, implying that that not all nonsingular flexible matrices have the inverse matrix. Under certain conditions upon the size of the uncertainties appearing in a nonsingular flexible matrix, a general theorem concerning the boundaries of its minors is presented which guarantees the existence of the inverse matrix of a nonsingular flexible matrix.

New central configurations of the (n + 1) -body problem

NASA Astrophysics Data System (ADS)

Fernandes, Antonio Carlos; Garcia, Braulio Augusto; Llibre, Jaume; Mello, Luis Fernando

2018-01-01

In this article we study central configurations of the (n + 1) -body problem. For the planar (n + 1) -body problem we study central configurations performed by n ≥ 2 bodies with equal masses at the vertices of a regular n-gon and one body with null mass. We also study spatial central configurations considering n bodies with equal masses at the vertices of a regular polyhedron and one body with null mass.

Scatterings and Quantum Effects in (Al ,In )N /GaN Heterostructures for High-Power and High-Frequency Electronics

NASA Astrophysics Data System (ADS)

Wang, Leizhi; Yin, Ming; Khan, Asif; Muhtadi, Sakib; Asif, Fatima; Choi, Eun Sang; Datta, Timir

2018-02-01

Charge transport in the wide-band-gap (Al ,In )N /GaN heterostructures with high carrier density approximately 2 ×1013 cm-2 is investigated over a large range of temperature (270 mK ≤T ≤280 K ) and magnetic field (0 ≤B ≤18 T ). We observe the first evidence of weak localization in the two-dimensional electron gas in this system. From the Shubnikov-de Haas (SdH) oscillations a relatively light effective mass of 0.23 me is determined. Furthermore, the linear dependence with temperature (T <20 K ) of the inelastic scattering rate (τi-1∝T ) is attributed to the phase breaking by electron-electron scattering. Also in the same temperature range the less-than unit ratio of quantum lifetime to Hall transport time (τq/τt<1 ) is taken to signify the dominance of small-angle scattering. Above 20 K, with increasing temperature scattering changes from acoustic phonon to optical phonon scattering, resulting in a rapid decrease in carrier mobility and increase in sheet resistance. Suppression of such scatterings will lead to higher mobility and a way forward to high-power and high-frequency electronics.

Compton scatter imaging: A promising modality for image guidance in lung stereotactic body radiation therapy.

PubMed

Redler, Gage; Jones, Kevin C; Templeton, Alistair; Bernard, Damian; Turian, Julius; Chu, James C H

2018-03-01

Lung stereotactic body radiation therapy (SBRT) requires delivering large radiation doses with millimeter accuracy, making image guidance essential. An approach to forming images of patient anatomy from Compton-scattered photons during lung SBRT is presented. To investigate the potential of scatter imaging, a pinhole collimator and flat-panel detector are used for spatial localization and detection of photons scattered during external beam therapy using lung SBRT treatment conditions (6 MV FFF beam). MCNP Monte Carlo software is used to develop a model to simulate scatter images. This model is validated by comparing experimental and simulated phantom images. Patient scatter images are then simulated from 4DCT data. Experimental lung tumor phantom images have sufficient contrast-to-noise to visualize the tumor with as few as 10 MU (0.5 s temporal resolution). The relative signal intensity from objects of different composition as well as lung tumor contrast for simulated phantom images agree quantitatively with experimental images, thus validating the Monte Carlo model. Scatter images are shown to display high contrast between different materials (lung, water, bone). Simulated patient images show superior (~double) tumor contrast compared to MV transmission images. Compton scatter imaging is a promising modality for directly imaging patient anatomy during treatment without additional radiation, and it has the potential to complement existing technologies and aid tumor tracking and lung SBRT image guidance. © 2018 American Association of Physicists in Medicine.

Large-deviation theory for diluted Wishart random matrices

NASA Astrophysics Data System (ADS)

Castillo, Isaac Pérez; Metz, Fernando L.

2018-03-01

Wishart random matrices with a sparse or diluted structure are ubiquitous in the processing of large datasets, with applications in physics, biology, and economy. In this work, we develop a theory for the eigenvalue fluctuations of diluted Wishart random matrices based on the replica approach of disordered systems. We derive an analytical expression for the cumulant generating function of the number of eigenvalues IN(x ) smaller than x ∈R+ , from which all cumulants of IN(x ) and the rate function Ψx(k ) controlling its large-deviation probability Prob[IN(x ) =k N ] ≍e-N Ψx(k ) follow. Explicit results for the mean value and the variance of IN(x ) , its rate function, and its third cumulant are discussed and thoroughly compared to numerical diagonalization, showing very good agreement. The present work establishes the theoretical framework put forward in a recent letter [Phys. Rev. Lett. 117, 104101 (2016), 10.1103/PhysRevLett.117.104101] as an exact and compelling approach to deal with eigenvalue fluctuations of sparse random matrices.

PoMiN: A Post-Minkowskian N-body Solver

NASA Astrophysics Data System (ADS)

Feng, Justin; Baumann, Mark; Hall, Bryton; Doss, Joel; Spencer, Lucas; Matzner, Richard

2018-06-01

In this paper, we introduce PoMiN, a lightweight N-body code based on the post-Minkowskian N-body Hamiltonian of Ledvinka et al., which includes general relativistic effects up to first order in Newton’s constant G, and all orders in the speed of light c. PoMiN is written in C and uses a fourth-order Runge–Kutta integration scheme. PoMiN has also been written to handle an arbitrary number of particles (both massive and massless), with a computational complexity that scales as O(N 2). We describe the methods we used to simplify and organize the Hamiltonian, and the tests we performed (convergence, conservation, and analytical comparison tests) to validate the code.

Electromagnetic Scattering by Spheroidal Volumes of Discrete Random Medium

NASA Technical Reports Server (NTRS)

Dlugach, Janna M.; Mishchenko, Michael I.

2017-01-01

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

Faddeev-chiral unitary approach to the K-d scattering length

NASA Astrophysics Data System (ADS)

Mizutani, T.; Fayard, C.; Saghai, B.; Tsushima, K.

2013-03-01

Our earlier Faddeev three-body study in the K--deuteron scattering length, AK-d, is revisited here in light of the recent developments on two fronts: (i) the improved chiral unitary approach to the theoretical description of the coupled K¯N related channels at low energies, and (ii) the new and improved measurement from SIDDHARTA Collaboration of the strong interaction energy shift and width in the lowest K--hydrogen atomic level. Those two, in combination, have allowed us to produce a reliable two-body input to the three-body calculation. All available low-energy K-p observables are well reproduced and predictions for the K¯N scattering lengths and amplitudes, (πΣ)∘ invariant-mass spectra, as well as for AK-d are put forward and compared with results from other sources. The findings of the present work are expected to be useful in interpreting the forthcoming data from CLAS, HADES, LEPS, and SIDDHARTA Collaborations.

Computer code for scattering from impedance bodies of revolution. Part 3: Surface impedance with s and phi variation. Analytical and numerical results

NASA Technical Reports Server (NTRS)

Uslenghi, Piergiorgio L. E.; Laxpati, Sharad R.; Kawalko, Stephen F.

1993-01-01

The third phase of the development of the computer codes for scattering by coated bodies that has been part of an ongoing effort in the Electromagnetics Laboratory of the Electrical Engineering and Computer Science Department at the University of Illinois at Chicago is described. The work reported discusses the analytical and numerical results for the scattering of an obliquely incident plane wave by impedance bodies of revolution with phi variation of the surface impedance. Integral equation formulation of the problem is considered. All three types of integral equations, electric field, magnetic field, and combined field, are considered. These equations are solved numerically via the method of moments with parametric elements. Both TE and TM polarization of the incident plane wave are considered. The surface impedance is allowed to vary along both the profile of the scatterer and in the phi direction. Computer code developed for this purpose determines the electric surface current as well as the bistatic radar cross section. The results obtained with this code were validated by comparing the results with available results for specific scatterers such as the perfectly conducting sphere. Results for the cone-sphere and cone-cylinder-sphere for the case of an axially incident plane were validated by comparing the results with the results with those obtained in the first phase of this project. Results for body of revolution scatterers with an abrupt change in the surface impedance along both the profile of the scatterer and the phi direction are presented.

Some new concepts in the n-body and 3-body problems

NASA Astrophysics Data System (ADS)

Kyrala, A.

1982-06-01

A new approach to the n-body problem in terms of an rms particle velocity and a harmonic mean particle separation has been constructed by using averaging procedures formulated in terms of a single parameter. A systematic classification of escape and collision processes by means of specific polynomials, which can be used somewhat like generating functions, is introduced. For n-body problems with non-null total angular momentum, an rms angular momentum is defined which together with a harmonic mean centroidal moment of inertia characterizes the rotational kinetic energy. Finally, a graphical construction for the equipotentials of the three-body problem is given and attention is drawn to the use of the apex, defined as the point of least average separation, in this problem. It is supposed that the n-bodies interact with one another via the Newtonian potential in an inertial system.

Application of H-matrices method to the calculation of the stress field in a viscoelastic medium

NASA Astrophysics Data System (ADS)

Ohtani, M.; Hirahara, K.

2017-12-01

In SW Japan, the Philippine Sea plate subducts from the south and the large earthquakes around M (Magnitude) 8 repeatedly occur at the plate boundary along the Nankai Trough, called as Nankai/Tonankai earthquakes. Near the rupture area of these earthquakes, the active volcanoes lines in the Kyushu region SW Japan, such as Sakurajima volcano. There are also distributed in the Tokai-Kanto region SE Japan, such as Mt. Fuji. The eruption of Mt. Fuji in 1707, called as Hoei eruption, have occurred 49 days after the one of the series of Nankai/Tonankai earthquakes, 1707 Hoei earthquake (M8.4). It suggests that the stress field due to the earthquake sometimes helps the volcanoes to erupt. When we consider the stress change due to the earthquake, the effect of viscoelastic deformation of the crust will be important. FEM is always used for modeling such inelastic effect. However, it requires the high computational cost of O(N3), where N is the number of discretized cells of the inelastic medium. Recently, a new method based on BIEM is proposed by Barbot and Fialko (2010). In their method, calculation of the stress field due to the inelastic strain is replaced to solve the inhomogeneous Navier's equation with equivalent body forces of the inelastic strain. Then, using the stress-strain greenfunction in an elastic medium, we can take into account the inelastic effect. In this study, we employ their method to evaluate the stress change at the active volcanoes around the Nankai/Tonankai earthquakes. Their method requires the computational cost and memory storage of O(N2). We try to reduce the computational amount and the memory by applying the fast computation method of H-matrices method. With H-matrices method, a dense matrix is divided into hierarchical structure of submatrices, and each submatrix is approximated to be low rank. When we divide the viscoelastic medium into N = 8,640 or 69,120 uniform cuboid cells and apply the H-matrices method, the required storage memory for

A covariant multiple scattering series for elastic projectile-target scattering

NASA Technical Reports Server (NTRS)

Gross, Franz; Maung-Maung, Khin

1989-01-01

A covariant formulation of the multiple scattering series for the optical potential is presented. The case of a scalar nucleon interacting with a spin zero isospin zero A-body target through meson exchange, is considered. It is shown that a covariant equation for the projectile-target t-matrix can be obtained which sums the ladder and crossed ladder diagrams efficiently. From this equation, a multiple scattering series for the optical potential is derived, and it is shown that in the impulse approximation, the two-body t-matrix associated with the first order optical potential is the one in which one particle is kept on mass-shell. The meaning of various terms in the multiple scattering series is given. The construction of the first-order optical potential for elastic scattering calculations is described.

Analysis of composite/difference field scattering properties between a slightly rough optical surface and multi-body defects.

PubMed

Gong, Lei; Wu, Zhensen; Gao, Ming; Qu, Tan

2018-03-20

The effective extraction of optical surface roughness and defect characteristic provide important realistic values to improve optical system efficiency. Based on finite difference time domain/multi-resolution time domain (FDTD/MRTD) mixed approach, composite scattering between a slightly rough optical surface and multi-body defect particles with different positions is investigated. The scattering contribution of defect particles or the slightly rough optical surface is presented. Our study provides a theoretical and technological basis for the nondestructive examination and optical performance design of nanometer structures.

Absorption and scattering of light by nonspherical particles. [in atmosphere

NASA Technical Reports Server (NTRS)

Bohren, C. F.

1986-01-01

Using the example of the polarization of scattered light, it is shown that the scattering matrices for identical, randomly ordered particles and for spherical particles are unequal. The spherical assumptions of Mie theory are therefore inconsistent with the random shapes and sizes of atmospheric particulates. The implications for corrections made to extinction measurements of forward scattering light are discussed. Several analytical methods are examined as potential bases for developing more accurate models, including Rayleigh theory, Fraunhoffer Diffraction theory, anomalous diffraction theory, Rayleigh-Gans theory, the separation of variables technique, the Purcell-Pennypacker method, the T-matrix method, and finite difference calculations.

Field matric potential sensor

DOEpatents

Hubbell, Joel M.; Sisson, James B.

2001-01-01

A method of determining matric potential of a sample, the method comprising placing the sample in a container, the container having an opening; and contacting the sample with a tensiometer via the opening. An apparatus for determining matric potential of a sample, the apparatus comprising a housing configured to receive a sample; a portable matric potential sensing device extending into the housing and having a porous member; and a wall closing the housing to insulate the sample and at least a portion of the matric potential sensing device including the porous member.

Full wave two-dimensional modeling of scattering and inverse scattering for layered rough surfaces with buried objects

NASA Astrophysics Data System (ADS)

Kuo, Chih-Hao

Efficient and accurate modeling of electromagnetic scattering from layered rough surfaces with buried objects finds applications ranging from detection of landmines to remote sensing of subsurface soil moisture. The formulation of a hybrid numerical/analytical solution to electromagnetic scattering from layered rough surfaces is first presented in this dissertation. The solution to scattering from each rough interface is sought independently based on the extended boundary condition method (EBCM), where the scattered fields of each rough interface are expressed as a summation of plane waves and then cast into reflection/transmission matrices. To account for interactions between multiple rough boundaries, the scattering matrix method (SMM) is applied to recursively cascade reflection and transmission matrices of each rough interface and obtain the composite reflection matrix from the overall scattering medium. The validation of this method against the Method of Moments (MoM) and Small Perturbation Method (SPM) is addressed and the numerical results which investigate the potential of low frequency radar systems in estimating deep soil moisture are presented. Computational efficiency of the proposed method is also discussed. In order to demonstrate the capability of this method in modeling coherent multiple scattering phenomena, the proposed method has been employed to analyze backscattering enhancement and satellite peaks due to surface plasmon waves from layered rough surfaces. Numerical results which show the appearance of enhanced backscattered peaks and satellite peaks are presented. Following the development of the EBCM/SMM technique, a technique which incorporates a buried object in layered rough surfaces by employing the T-matrix method and the cylindrical-to-spatial harmonics transformation is proposed. Validation and numerical results are provided. Finally, a multi-frequency polarimetric inversion algorithm for the retrieval of subsurface soil properties

Light scattering and absorption by space weathered planetary bodies: Novel numerical solution

NASA Astrophysics Data System (ADS)

Markkanen, Johannes; Väisänen, Timo; Penttilä, Antti; Muinonen, Karri

2017-10-01

Airless planetary bodies are exposed to space weathering, i.e., energetic electromagnetic and particle radiation, implantation and sputtering from solar wind particles, and micrometeorite bombardment.Space weathering is known to alter the physical and chemical composition of the surface of an airless body (C. Pieters et al., J. Geophys. Res. Planets, 121, 2016). From the light scattering perspective, one of the key effects is the production of nanophase iron (npFe0) near the exposed surfaces (B. Hapke, J. Geophys. Res., 106, E5, 2001). At visible and ultraviolet wavelengths these particles have a strong electromagnetic response which has a major impact on scattering and absorption features. Thus, to interpret the spectroscopic observations of space-weathered asteroids, the model should treat the contributions of the npFe0 particles rigorously.Our numerical approach is based on the hierarchical geometric optics (GO) and radiative transfer (RT). The modelled asteroid is assumed to consist of densely packed silicate grains with npFe0 inclusions. We employ our recently developed RT method for dense random media (K. Muinonen, et al., Radio Science, submitted, 2017) to compute the contributions of the npFe0 particles embedded in silicate grains. The dense media RT method requires computing interactions of the npFe0 particles in the volume element for which we use the exact fast superposition T-matrix method (J. Markkanen, and A.J. Yuffa, JQSRT 189, 2017). Reflections and refractions on the grain surface and propagation in the grain are addressed by the GO. Finally, the standard RT is applied to compute scattering by the entire asteroid.Our numerical method allows for a quantitative interpretation of the spectroscopic observations of space-weathered asteroids. In addition, it may be an important step towards more rigorous a thermophysical model of asteroids when coupled with the radiative and conductive heat transfer techniques.Acknowledgments. Research supported by

Random matrix theory of singular values of rectangular complex matrices I: Exact formula of one-body distribution function in fixed-trace ensemble

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adachi, Satoshi; Toda, Mikito; Kubotani, Hiroto

The fixed-trace ensemble of random complex matrices is the fundamental model that excellently describes the entanglement in the quantum states realized in a coupled system by its strongly chaotic dynamical evolution [see H. Kubotani, S. Adachi, M. Toda, Phys. Rev. Lett. 100 (2008) 240501]. The fixed-trace ensemble fully takes into account the conservation of probability for quantum states. The present paper derives for the first time the exact analytical formula of the one-body distribution function of singular values of random complex matrices in the fixed-trace ensemble. The distribution function of singular values (i.e. Schmidt eigenvalues) of a quantum state ismore » so important since it describes characteristics of the entanglement in the state. The derivation of the exact analytical formula utilizes two recent achievements in mathematics, which appeared in 1990s. The first is the Kaneko theory that extends the famous Selberg integral by inserting a hypergeometric type weight factor into the integrand to obtain an analytical formula for the extended integral. The second is the Petkovsek-Wilf-Zeilberger theory that calculates definite hypergeometric sums in a closed form.« less

Encoding the structure of many-body localization with matrix product operators

NASA Astrophysics Data System (ADS)

Pekker, David; Clark, Bryan K.

2015-03-01

Anderson insulators are non-interacting disordered systems which have localized single particle eigenstates. The interacting analogue of Anderson insulators are the Many-Body Localized (MBL) phases. The natural language for representing the spectrum of the Anderson insulator is that of product states over the single-particle modes. We show that product states over Matrix Product Operators of small bond dimension is the corresponding natural language for describing the MBL phases. In this language all of the many-body eigenstates are encode by Matrix Product States (i.e. DMRG wave function) consisting of only two sets of low bond-dimension matrices per site: the Gi matrix corresponding to the local ground state on site i and the Ei matrix corresponding to the local excited state. All 2 n eigenstates can be generated from all possible combinations of these matrices.

Polarization characteristics of inhomogeneous models of nonstationary light-scattering media

NASA Astrophysics Data System (ADS)

Smolinskii, E. S.; Petruk, V. G.; Lavreniuk, V. I.

1990-09-01

The optical parameters of monodisperse layers of MgO and turpentine black with different surface particle densities are investigated using a polarization spectrum extinction meter. A method for determining the volume density of a real nonstationary scattering and absorbing medium is proposed which is based on the transfer equations. Graphical and spectroanalytical data are presented which allow for various optical and physical factors. Polarization measurements of the layers are carried out, and scattering matrices are obtained.

Correlations of π N partial waves for multireaction analyses

DOE PAGES

Doring, M.; Revier, J.; Ronchen, D.; ...

2016-06-15

In the search for missing baryonic resonances, many analyses include data from a variety of pion- and photon-induced reactions. For elastic πN scattering, however, usually the partial waves of the SAID (Scattering Analysis Interactive Database) or other groups are fitted, instead of data. We provide the partial-wave covariance matrices needed to perform correlated χ 2 fits, in which the obtained χ 2 equals the actual χ 2 up to nonlinear and normalization corrections. For any analysis relying on partial waves extracted from elastic pion scattering, this is a prerequisite to assess the significance of resonance signals and to assign anymore » uncertainty on results. Lastly, the influence of systematic errors is also considered.« less

Rotationally inelastic scattering of methyl radicals with Ar and N{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tkáč, Ondřej; Orr-Ewing, Andrew J., E-mail: a.orr-ewing@bristol.ac.uk; Ma, Qianli

2015-01-07

The rotationally inelastic scattering of methyl radical with Ar and N{sub 2} is examined at collision energies of 330 ± 25 cm{sup −1} and 425 ± 50 cm{sup −1}, respectively. Differential cross sections (DCSs) were measured for different final n′ rotational levels (up to n′ = 5) of the methyl radicals, averaged over k′ sub-levels, using a crossed molecular beam machine with velocity map imaging. For Ar as a collision partner, we present a newly constructed ab initio potential energy surface and quantum mechanical scattering calculations of state-resolved DCSs. These computed DCSs agree well with the measurements. The DCSs formore » both Ar and N{sub 2} collision partners are strongly forward peaked for all spectroscopic lines measured. For scattering angles below 60°, the theoretical CD{sub 3}–Ar DCSs show diffraction oscillations that become less pronounced as n′ increases, but these oscillations are not resolved experimentally. Comparisons are drawn with our recently reported DCSs for scattering of methyl radicals with He atoms.« less

Fast calculation of the light differential scattering cross section of optically soft and convex bodies

NASA Astrophysics Data System (ADS)

Gruy, Frédéric

2014-02-01

Depending on the range of size and the refractive index value, an optically soft particle follows Rayleigh-Debye-Gans or RDG approximation or Van de Hulst approximation. Practically the first one is valid for small particles whereas the second one works for large particles. Klett and Sutherland (Klett JD, Sutherland RA. App. Opt. 1992;31:373) proved that the Wentzel-Kramers-Brillouin or WKB approximation leads to accurate values of the differential scattering cross section of sphere and cylinder over a wide range of size. In this paper we extend the work of Klett and Sutherland by proposing a method allowing a fast calculation of the differential scattering cross section for any shape of particle with a given orientation and illuminated by unpolarized light. Our method is based on a geometrical approximation of the particle by replacing each geometrical cross section by an ellipse and then by exactly evaluating the differential scattering cross section of the newly generated body. The latter one contains only two single integrals.

The real and apparent convergence of N-body simulations of the dark matter structures: Is the Navarro-Frenk-White profile real?

NASA Astrophysics Data System (ADS)

Baushev, A. N.

2015-03-01

While N-body simulations suggest a cuspy profile in the centra of the dark matter halos of galaxies, the majority of astronomical observations favor a relatively soft cored density distribution of these regions. The routine method of testing the convergence of N-body simulations (in particular, the negligibility of two-body scattering effect) is to find the conditions under which formed structures is insensitive to numerical parameters. The results obtained with this approach suggest a surprisingly minor role of the particle collisions: the central density profile remains untouched and close to the Navarro-Frenk-White shape, even if the simulation time significantly exceeds the collisional relaxation time τr . In order to check the influence of the unphysical test body collisions we use the Fokker-Planck equation. It turns out that a profile ρ ∝r-β where β ≃ 1 is an attractor: the Fokker-Planck diffusion transforms any reasonable initial distribution into it in a time shorter than τr , and then the cuspy profile should survive much longer than τr , since the Fokker-Planck diffusion is self-compensated if β ≃ 1 . Thus the purely numerical effect of test body scattering may create a stable NFW-like pseudosolution. Moreover, its stability may be mistaken for the simulation convergence. We present analytical estimations for this potential bias effect and call for numerical tests. For that purpose, we suggest a simple test that can be performed as the simulation progresses and would indicate the magnitude of the collisional influence and the veracity of the simulation results.

The Naked Truth: The Face and Body Sensitive N170 Response Is Enhanced for Nude Bodies

PubMed Central

Hietanen, Jari K.; Nummenmaa, Lauri

2011-01-01

Recent event-related potential studies have shown that the occipitotemporal N170 component - best known for its sensitivity to faces - is also sensitive to perception of human bodies. Considering that in the timescale of evolution clothing is a relatively new invention that hides the bodily features relevant for sexual selection and arousal, we investigated whether the early N170 brain response would be enhanced to nude over clothed bodies. In two experiments, we measured N170 responses to nude bodies, bodies wearing swimsuits, clothed bodies, faces, and control stimuli (cars). We found that the N170 amplitude was larger to opposite and same-sex nude vs. clothed bodies. Moreover, the N170 amplitude increased linearly as the amount of clothing decreased from full clothing via swimsuits to nude bodies. Strikingly, the N170 response to nude bodies was even greater than that to faces, and the N170 amplitude to bodies was independent of whether the face of the bodies was visible or not. All human stimuli evoked greater N170 responses than did the control stimulus. Autonomic measurements and self-evaluations showed that nude bodies were affectively more arousing compared to the other stimulus categories. We conclude that the early visual processing of human bodies is sensitive to the visibility of the sex-related features of human bodies and that the visual processing of other people's nude bodies is enhanced in the brain. This enhancement is likely to reflect affective arousal elicited by nude bodies. Such facilitated visual processing of other people's nude bodies is possibly beneficial in identifying potential mating partners and competitors, and for triggering sexual behavior. PMID:22110574

Plane-dependent ML scatter scaling: 3D extension of the 2D simulated single scatter (SSS) estimate.

PubMed

Rezaei, Ahmadreza; Salvo, Koen; Vahle, Thomas; Panin, Vladimir; Casey, Michael; Boada, Fernando; Defrise, Michel; Nuyts, Johan

2017-07-24

Scatter correction is typically done using a simulation of the single scatter, which is then scaled to account for multiple scatters and other possible model mismatches. This scaling factor is determined by fitting the simulated scatter sinogram to the measured sinogram, using only counts measured along LORs that do not intersect the patient body, i.e. 'scatter-tails'. Extending previous work, we propose to scale the scatter with a plane dependent factor, which is determined as an additional unknown in the maximum likelihood (ML) reconstructions, using counts in the entire sinogram rather than only the 'scatter-tails'. The ML-scaled scatter estimates are validated using a Monte-Carlo simulation of a NEMA-like phantom, a phantom scan with typical contrast ratios of a 68 Ga-PSMA scan, and 23 whole-body 18 F-FDG patient scans. On average, we observe a 12.2% change in the total amount of tracer activity of the MLEM reconstructions of our whole-body patient database when the proposed ML scatter scales are used. Furthermore, reconstructions using the ML-scaled scatter estimates are found to eliminate the typical 'halo' artifacts that are often observed in the vicinity of high focal uptake regions.

Structure of 10 N in 9 C+p resonance scattering

DOE PAGES

Hooker, J.; Rogachev, G. V.; Goldberg, V. Z.; ...

2017-03-17

We studied the structure of exotic nucleus 10N using 9C+p resonance scattering. Two ℓ=0 resonances were found to be the lowest states in 10N. Furthermore, the ground state of 10N is unbound with respect to proton decay by 2.2(2) or 1.9(2) MeV depending on the 2 -or 1 -spin-parity assignment, and the first excited state is unbound by 2.8(2) MeV.

Reflection matrices with U q [osp(2) (2|2m)] symmetry

NASA Astrophysics Data System (ADS)

Vieira, R. S.; Lima-Santos, A.

2017-09-01

We propose a classification of the reflection K-matrices (solutions of the boundary Yang-Baxter equation) for the Uq[osp(2)(2\\vert 2m)]=Uq[C(2)(m+1)] vertex-model. We found four families of solutions, namely, the complete solutions, in which no elements of the reflection K-matrix is null, the block-diagonal solutions, the X-shape solutions and the diagonal solutions. We highlight that these diagonal K-matrices also hold for the Uq[osp(2)(2n+2\\vert 2m)]=Uq[D(2)(n+1, m)] vertex-model.

Probing the Topology of Density Matrices

NASA Astrophysics Data System (ADS)

Bardyn, Charles-Edouard; Wawer, Lukas; Altland, Alexander; Fleischhauer, Michael; Diehl, Sebastian

2018-01-01

The mixedness of a quantum state is usually seen as an adversary to topological quantization of observables. For example, exact quantization of the charge transported in a so-called Thouless adiabatic pump is lifted at any finite temperature in symmetry-protected topological insulators. Here, we show that certain directly observable many-body correlators preserve the integrity of topological invariants for mixed Gaussian quantum states in one dimension. Our approach relies on the expectation value of the many-body momentum-translation operator and leads to a physical observable—the "ensemble geometric phase" (EGP)—which represents a bona fide geometric phase for mixed quantum states, in the thermodynamic limit. In cyclic protocols, the EGP provides a topologically quantized observable that detects encircled spectral singularities ("purity-gap" closing points) of density matrices. While we identify the many-body nature of the EGP as a key ingredient, we propose a conceptually simple, interferometric setup to directly measure the latter in experiments with mesoscopic ensembles of ultracold atoms.

Medium-induced change of the optical response of metal clusters in rare-gas matrices

NASA Astrophysics Data System (ADS)

Xuan, Fengyuan; Guet, Claude

2017-10-01

Interaction with the surrounding medium modifies the optical response of embedded metal clusters. For clusters from about ten to a few hundreds of silver atoms, embedded in rare-gas matrices, we study the environment effect within the matrix random phase approximation with exact exchange (RPAE) quantum approach, which has proved successful for free silver clusters. The polarizable surrounding medium screens the residual two-body RPAE interaction, adds a polarization term to the one-body potential, and shifts the vacuum energy of the active delocalized valence electrons. Within this model, we calculate the dipole oscillator strength distribution for Ag clusters embedded in helium droplets, neon, argon, krypton, and xenon matrices. The main contribution to the dipole surface plasmon red shift originates from the rare-gas polarization screening of the two-body interaction. The large size limit of the dipole surface plasmon agrees well with the classical prediction.

Modeling light scattering by mineral dust particles using spheroids

NASA Astrophysics Data System (ADS)

Merikallio, Sini; Nousiainen, Timo

Suspended dust particles have a considerable influence on light scattering in both terrestrial and planetary atmospheres and can therefore have a large effect on the interpretation of remote sensing measurements. Assuming dust particles to be spherical is known to produce inaccurate results when modeling optical properties of real mineral dust particles. Yet this approximation is widely used for its simplicity. Here, we simulate light scattering by mineral dust particles using a distribution of model spheroids. This is done by comparing scattering matrices calculated from a dust optical database of Dubovik et al. [2006] with those measured in the laboratory by Volten et al. [2001]. Wavelengths of 441,6 nm and 632,8 nm and refractive indexes of Re = 1.55 -1.7 and Im = 0.001i -0.01i were adopted in this study. Overall, spheroids are found to fit the measurements significantly better than Mie spheres. Further, we confirm that the shape distribution parametrization developed in Nousiainen et al. (2006) significantly improves the accuracy of simulated single-scattering for small mineral dust particles. The spheroid scheme should therefore yield more reliable interpretations of remote sensing data from dusty planetary atmospheres. While the spheroidal scheme is superior to spheres in remote sensing applications, its performance is far from perfect especially for samples with large particles. Thus, additional advances are clearly possible. Further studies of the Martian atmosphere are currently under way. Dubovik et al. (2006) Application of spheroid models to account for aerosol particle nonspheric-ity in remote sensing of desert dust, JGR, Vol. 111, D11208 Volten et al. (2001) Scattering matrices of mineral aerosol particles at 441.6 nm and 632.8 nm, JGR, Vol. 106, No. D15, pp. 17375-17401 Nousiainen et al. (2006) Light scattering modeling of small feldspar aerosol particles using polyhedral prisms and spheroids, JQSRT 101, pp. 471-487

Scattered surface wave energy in the seismic coda

USGS Publications Warehouse

Zeng, Y.

2006-01-01

One of the many important contributions that Aki has made to seismology pertains to the origin of coda waves (Aki, 1969; Aki and Chouet, 1975). In this paper, I revisit Aki's original idea of the role of scattered surface waves in the seismic coda. Based on the radiative transfer theory, I developed a new set of scattered wave energy equations by including scattered surface waves and body wave to surface wave scattering conversions. The work is an extended study of Zeng et al. (1991), Zeng (1993) and Sato (1994a) on multiple isotropic-scattering, and may shed new insight into the seismic coda wave interpretation. The scattering equations are solved numerically by first discretizing the model at regular grids and then solving the linear integral equations iteratively. The results show that scattered wave energy can be well approximated by body-wave to body wave scattering at earlier arrival times and short distances. At long distances from the source, scattered surface waves dominate scattered body waves at surface stations. Since surface waves are 2-D propagating waves, their scattered energies should in theory follow a common decay curve. The observed common decay trends on seismic coda of local earthquake recordings particular at long lapse times suggest that perhaps later seismic codas are dominated by scattered surface waves. When efficient body wave to surface wave conversion mechanisms are present in the shallow crustal layers, such as soft sediment layers, the scattered surface waves dominate the seismic coda at even early arrival times for shallow sources and at later arrival times for deeper events.

Correlation effects in elastic e-N2 scattering

NASA Technical Reports Server (NTRS)

Huo, Winifred M.; Lima, Marco A. P.; Gibson, Thomas L.; Mckoy, Vincent

1987-01-01

The Schwinger multichannel formulation has been applied to study the role of electron correlation in low-energy e-N2 scattering. For the five nonresonant partial-wave channels studied here, angular correlation is found to be much more important than radial correlation. The calculated total and differential cross sections agree well with experiment except for the differential cross sections at 1.5 eV.

Three-body model for the two-neutron emission of Be 16 [Three-body model for the two-neutron decay of 16Be

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lovell, A. E.; Nunes, F. M.; Thompson, I. J.

While diproton emission was first theorized in 1960 and first measured in 2002, it was first observed only in 2012. The measurement of 14Be in coincidence with two neutrons suggests that 16Be does decay through the simultaneous emission of two strongly correlated neutrons. In this study, we construct a full three-body model of 16Be (as 14Be + n + n) in order to investigate its configuration in the continuum and, in particular, the structure of its ground state. Here, in order to describe the three-body system, effective n – 14Be potentials were constructed, constrained by the experimental information on 15Be.more » The hyperspherical R-matrix method was used to solve the three-body scattering problem, and the resonance energy of 16Be was extracted from a phase-shift analysis. As a result, in order to reproduce the experimental resonance energy of 16Be within this three-body model, a three-body interaction was needed. For extracting the width of the ground state of 16Be, we use the full width at half maximum of the derivative of the three-body eigenphase shifts and the width of the three-body elastic scattering cross section. In conclusion, our results confirm a dineutron structure for 16Be, dependent on the internal structure of the subsystem 15Be.« less

Three-body model for the two-neutron emission of Be 16 [Three-body model for the two-neutron decay of 16Be

DOE PAGES

Lovell, A. E.; Nunes, F. M.; Thompson, I. J.

2017-03-10

While diproton emission was first theorized in 1960 and first measured in 2002, it was first observed only in 2012. The measurement of 14Be in coincidence with two neutrons suggests that 16Be does decay through the simultaneous emission of two strongly correlated neutrons. In this study, we construct a full three-body model of 16Be (as 14Be + n + n) in order to investigate its configuration in the continuum and, in particular, the structure of its ground state. Here, in order to describe the three-body system, effective n – 14Be potentials were constructed, constrained by the experimental information on 15Be.more » The hyperspherical R-matrix method was used to solve the three-body scattering problem, and the resonance energy of 16Be was extracted from a phase-shift analysis. As a result, in order to reproduce the experimental resonance energy of 16Be within this three-body model, a three-body interaction was needed. For extracting the width of the ground state of 16Be, we use the full width at half maximum of the derivative of the three-body eigenphase shifts and the width of the three-body elastic scattering cross section. In conclusion, our results confirm a dineutron structure for 16Be, dependent on the internal structure of the subsystem 15Be.« less

Cryptohermitian Picture of Scattering Using Quasilocal Metric Operators

NASA Astrophysics Data System (ADS)

Znojil, Miloslav

2009-08-01

One-dimensional unitary scattering controlled by non-Hermitian (typically, PT-symmetric) quantum Hamiltonians H ≠ H† is considered. Treating these operators via Runge-Kutta approximation, our three-Hilbert-space formulation of quantum theory is reviewed as explaining the unitarity of scattering. Our recent paper on bound states [Znojil M., SIGMA 5 (2009), 001, 19 pages, arXiv:0901.0700] is complemented by the text on scattering. An elementary example illustrates the feasibility of the resulting innovative theoretical recipe. A new family of the so called quasilocal inner products in Hilbert space is found to exist. Constructively, these products are all described in terms of certain non-equivalent short-range metric operators Θ ≠ I represented, in Runge-Kutta approximation, by (2R-1)-diagonal matrices.

Green's function multiple-scattering theory with a truncated basis set: An augmented-KKR formalism

NASA Astrophysics Data System (ADS)

Alam, Aftab; Khan, Suffian N.; Smirnov, A. V.; Nicholson, D. M.; Johnson, Duane D.

2014-11-01

The Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an efficient site-centered, electronic-structure technique for addressing an assembly of N scatterers. Wave functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number Lmax=(l,mmax), while scattering matrices, which determine spectral properties, are truncated at Lt r=(l,mt r) where phase shifts δl >ltr are negligible. Historically, Lmax is set equal to Lt r, which is correct for large enough Lmax but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for Lmax>Lt r with δl >ltr set to zero [X.-G. Zhang and W. H. Butler, Phys. Rev. B 46, 7433 (1992), 10.1103/PhysRevB.46.7433]. We present a numerically efficient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R3 process with rank N (ltr+1 ) 2 ] and includes higher-L contributions via linear algebra [R2 process with rank N (lmax+1) 2 ]. The augmented-KKR approach yields properly normalized wave functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe, and L 1 0 CoPt and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus Lmax for a given Lt r.

Green's function multiple-scattering theory with a truncated basis set: An augmented-KKR formalism

DOE PAGES

Alam, Aftab; Khan, Suffian N.; Smirnov, A. V.; ...

2014-11-04

Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an ecient sitecentered, electronic-structure technique for addressing an assembly of N scatterers. Wave-functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number L max = (l,m) max, while scattering matrices, which determine spectral properties, are truncated at L tr = (l,m) tr where phase shifts δl>l tr are negligible. Historically, L max is set equal to L tr, which is correct for large enough L max but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for L maxmore » > L tr with δl>l tr set to zero [Zhang and Butler, Phys. Rev. B 46, 7433]. We present a numerically ecient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R 3 process with rank N(l tr + 1) 2] and includes higher-L contributions via linear algebra [R 2 process with rank N(l max +1) 2]. Augmented-KKR approach yields properly normalized wave-functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe and L1 0 CoPt, and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus L max for a given L tr.« less

Fungible Correlation Matrices: A Method for Generating Nonsingular, Singular, and Improper Correlation Matrices for Monte Carlo Research.

PubMed

Waller, Niels G

2016-01-01

For a fixed set of standardized regression coefficients and a fixed coefficient of determination (R-squared), an infinite number of predictor correlation matrices will satisfy the implied quadratic form. I call such matrices fungible correlation matrices. In this article, I describe an algorithm for generating positive definite (PD), positive semidefinite (PSD), or indefinite (ID) fungible correlation matrices that have a random or fixed smallest eigenvalue. The underlying equations of this algorithm are reviewed from both algebraic and geometric perspectives. Two simulation studies illustrate that fungible correlation matrices can be profitably used in Monte Carlo research. The first study uses PD fungible correlation matrices to compare penalized regression algorithms. The second study uses ID fungible correlation matrices to compare matrix-smoothing algorithms. R code for generating fungible correlation matrices is presented in the supplemental materials.

Emergent causality and the N-photon scattering matrix in waveguide QED

NASA Astrophysics Data System (ADS)

Sánchez-Burillo, E.; Cadarso, A.; Martín-Moreno, L.; García-Ripoll, J. J.; Zueco, D.

2018-01-01

In this work we discuss the emergence of approximate causality in a general setup from waveguide QED—i.e. a one-dimensional propagating field interacting with a scatterer. We prove that this emergent causality translates into a structure for the N-photon scattering matrix. Our work builds on the derivation of a Lieb-Robinson-type bound for continuous models and for all coupling strengths, as well as on several intermediate results, of which we highlight: (i) the asymptotic independence of space-like separated wave packets, (ii) the proper definition of input and output scattering states, and (iii) the characterization of the ground state and correlations in the model. We illustrate our formal results by analyzing the two-photon scattering from a quantum impurity in the ultrastrong coupling regime, verifying the cluster decomposition and ground-state nature. Besides, we generalize the cluster decomposition if inelastic or Raman scattering occurs, finding the structure of the S-matrix in momentum space for linear dispersion relations. In this case, we compute the decay of the fluorescence (photon-photon correlations) caused by this S-matrix.

Plane-dependent ML scatter scaling: 3D extension of the 2D simulated single scatter (SSS) estimate

NASA Astrophysics Data System (ADS)

Rezaei, Ahmadreza; Salvo, Koen; Vahle, Thomas; Panin, Vladimir; Casey, Michael; Boada, Fernando; Defrise, Michel; Nuyts, Johan

2017-08-01

Scatter correction is typically done using a simulation of the single scatter, which is then scaled to account for multiple scatters and other possible model mismatches. This scaling factor is determined by fitting the simulated scatter sinogram to the measured sinogram, using only counts measured along LORs that do not intersect the patient body, i.e. ‘scatter-tails’. Extending previous work, we propose to scale the scatter with a plane dependent factor, which is determined as an additional unknown in the maximum likelihood (ML) reconstructions, using counts in the entire sinogram rather than only the ‘scatter-tails’. The ML-scaled scatter estimates are validated using a Monte-Carlo simulation of a NEMA-like phantom, a phantom scan with typical contrast ratios of a 68Ga-PSMA scan, and 23 whole-body 18F-FDG patient scans. On average, we observe a 12.2% change in the total amount of tracer activity of the MLEM reconstructions of our whole-body patient database when the proposed ML scatter scales are used. Furthermore, reconstructions using the ML-scaled scatter estimates are found to eliminate the typical ‘halo’ artifacts that are often observed in the vicinity of high focal uptake regions.

Quantum Scattering Study of Ro-Vibrational Excitations in N+N(sub 2) Collisions under Re-entry Conditions

NASA Technical Reports Server (NTRS)

Wang, Dunyou; Stallcop, James R.; Dateo, Christopher E.; Schwenke, David W.; Huo, Winifred M.

2004-01-01

A three-dimensional time-dependent quantum dynamics approach using a recently developed ab initio potential energy surface is applied to study ro-vibrational excitation in N+N2 exchange scattering for collision energies in the range 2.1- 3.2 eV. State-to-state integral exchange cross sections are examined to determine the distribution of excited rotational states of N(sub 2). The results demonstrate that highly-excited rotational states are produced by exchange scattering and furthermore, that the maximum value of (Delta)j increases rapidly with increasing collision energies. Integral exchange cross sections and exchange rate constants for excitation to the lower (upsilon = 0-3) vibrational energy levels are presented as a function of the collision energy. Excited-vibrational-state distributions for temperatures at 2,000 K and 10,000 K are included.

VX fate on common matrices: evaporation versus degradation.

PubMed

Columbus, Ishay; Waysbort, Daniel; Marcovitch, Itzhak; Yehezkel, Lea; Mizrahi, Dana M

2012-04-03

A study of the volatilization rate of the nerve agent VX (O-ethyl S-2-(N,N-diisopropylamino)ethyl methylphosphonothiolate) from various urban matrices in a specially designed climatic chamber (model system) is described. The performance of the model system combined with the analytical procedure produced profiles of vapor concentration obtained from samples of VX dispersed as small droplets on the surfaces of the matrices. The results indicated that the bitumen-containing surfaces such as asphalt blocks and bitumen sheets conserve VX and slow-release part of it over a long period of time. No complete mass balance could be obtained for these surfaces. Influence of environmental and experimental parameters as well as the efficacy of decontamination procedure were also measured. From smooth surface tiles a fast release of VX was measured and almost a complete mass balance was obtained, which characterizes the behavior of inert surfaces. Experiments carried out on concrete blocks showed fast decay of the concentration profile along with a very poor reconstruction of the initial quantity of VX, implying that this matrix degraded VX actively due to its multiple basic catalytic sites. To complement this study, solid-state NMR measurements were compared to add data concerning agent-fate within the matrices.

Phase object retrieval through scattering medium

NASA Astrophysics Data System (ADS)

Zhao, Ming; Zhao, Meijing; Wu, Houde; Xu, Wenhai

2018-05-01

Optical imaging through a scattering medium has been an interesting and important research topic, especially in the field of biomedical imaging. However, it is still a challenging task due to strong scattering. This paper proposes to recover the phase object behind the scattering medium from one single-shot speckle intensity image using calibrated transmission matrices (TMs). We construct the forward model as a non-linear mapping, since the intensity image loses the phase information, and then a generalized phase retrieval algorithm is employed to recover the hidden object. Moreover, we show that a phase object can be reconstructed with a small portion of the speckle image captured by the camera. The simulation is performed to demonstrate our scheme and test its performance. Finally, a real experiment is set up, we measure the TMs from the scattering medium, and then use it to reconstruct the hidden object. We show that a phase object of size 32 × 32 is retrieved from 150 × 150 speckle grains, which is only 1/50 of the speckles area. We believe our proposed method can benefit the community of imaging through the scattering medium.

Human elastin polypeptides improve the biomechanical properties of three-dimensional matrices through the regulation of elastogenesis.

PubMed

Boccafoschi, Francesca; Ramella, Martina; Sibillano, Teresa; De Caro, Liberato; Giannini, Cinzia; Comparelli, Roberto; Bandiera, Antonella; Cannas, Mario

2015-03-01

The replacement of diseased tissues with biological substitutes with suitable biomechanical properties is one of the most important goal in tissue engineering. Collagen represents a satisfactory choice for scaffolds. Unfortunately, the lack of elasticity represents a restriction to a wide use of collagen for several applications. In this work, we studied the effect of human elastin-like polypeptide (HELP) as hybrid collagen-elastin matrices. In particular, we studied the biomechanical properties of collagen/HELP scaffolds considering several components involved in ECM remodeling (elastin, collagen, fibrillin, lectin-like receptor, metalloproteinases) and cell phenotype (myogenin, myosin heavy chain) with particular awareness for vascular tissue engineering applications. Elastin and collagen content resulted upregulated in collagen-HELP matrices, even showing an improved structural remodeling through the involvement of proteins to a ECM remodeling activity. Moreover, the hybrid matrices enhanced the contractile activity of C2C12 cells concurring to improve the mechanical properties of the scaffold. Finally, small-angle X-ray scattering analyses were performed to enable a very detailed analysis of the matrices at the nanoscale, comparing the scaffolds with native blood vessels. In conclusion, our work shows the use of recombinant HELP, as a very promising complement able to significantly improve the biomechanical properties of three-dimensional collagen matrices in terms of tensile stress and elastic modulus. © 2014 Wiley Periodicals, Inc.

Evaluation of dual polarization scattering matrix radar rain backscatter measurements in the X- and Q-bands

NASA Astrophysics Data System (ADS)

Agrawal, A. P.; Carnegie, D. W.; Boerner, W.-M.

This paper presents an evaluation of polarimetric rain backscatter measurements collected with coherent dual polarization radar systems in the X (8.9 GHz) and Q (45GHz) bands, the first being operated in a pulsed mode and the second being a FM-CW system. The polarimetric measurement data consisted for each band of fifty files of time-sequential scattering matrix measurements expressed in terms of a linear (H, V) antenna polarization state basis. The rain backscattering takes place in a rain cell defined by the beam widths and down range distances of 275 ft through 325 ft and the scattering matrices were measured far below the hydrometeoric scattering center decorrelation time so that ensemble averaging of time-sequential scattering matrices may be applied. In the data evaluation great care was taken in determining: (1) polarimetric Doppler velocities associated with the motion of descending oscillating raindrops and/or eddies within the moving swaths of coastal rain showers, and (2) also the properties of the associated co/cross-polarization rain clutter nulls and their distributions on the Poincare polarization sphere.

Nonperturbative NN scattering in {sup 3}S{sub 1}–{sup 3}D{sub 1} channels of EFT(⁄π)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Ji-Feng, E-mail: jfyang@phy.ecnu.edu.cn

2013-12-15

The closed-form T matrices in the {sup 3}S{sub 1}–{sup 3}D{sub 1} channels of EFT(⁄π) for NN scattering with the potentials truncated at order O(Q{sup 4}) are presented with the nonperturbative divergences parametrized in a general manner. The stringent constraints imposed by the closed form of the T matrices are exploited in the underlying theory perspective and turned into virtues in the implementation of subtractions and the manifestation of power counting rules in nonperturbative regimes, leading us to the concept of EFT scenario. A number of scenarios of the EFT description of NN scattering are compared with PSA data in termsmore » of effective range expansion and {sup 3}S{sub 1} phase shifts, showing that it is favorable to proceed in a scenario with conventional EFT couplings and sophisticated renormalization in order to have large NN scattering lengths. The informative utilities of fine tuning are demonstrated in several examples and naturally interpreted in the underlying theory perspective. In addition, some of the approaches adopted in the recent literature are also addressed in the light of EFT scenario. -- Highlights: •Closed-form unitary T matrices for NN scattering are obtained in EFT(⁄π). •Nonperturbative properties inherent in such closed-form T matrices are explored. •Nonperturbative renormalization is implemented through exploiting these properties. •Unconventional power counting of couplings is shown to be less favored by PSA data. •The ideas about nonperturbative renormalization here might have wider applications.« less

Atmospheric particulate analysis using angular light scattering

NASA Technical Reports Server (NTRS)

Hansen, M. Z.

1980-01-01

Using the light scattering matrix elements measured by a polar nephelometer, a procedure for estimating the characteristics of atmospheric particulates was developed. A theoretical library data set of scattering matrices derived from Mie theory was tabulated for a range of values of the size parameter and refractive index typical of atmospheric particles. Integration over the size parameter yielded the scattering matrix elements for a variety of hypothesized particulate size distributions. A least squares curve fitting technique was used to find a best fit from the library data for the experimental measurements. This was used as a first guess for a nonlinear iterative inversion of the size distributions. A real index of 1.50 and an imaginary index of -0.005 are representative of the smoothed inversion results for the near ground level atmospheric aerosol in Tucson.

Symmetry breaking and the geometry of reduced density matrices

NASA Astrophysics Data System (ADS)

Zauner, V.; Draxler, D.; Vanderstraeten, L.; Haegeman, J.; Verstraete, F.

2016-11-01

The concept of symmetry breaking and the emergence of corresponding local order parameters constitute the pillars of modern day many body physics. We demonstrate that the existence of symmetry breaking is a consequence of the geometric structure of the convex set of reduced density matrices of all possible many body wavefunctions. The surfaces of these convex bodies exhibit non-analyticities, which signal the emergence of symmetry breaking and of an associated order parameter and also show different characteristics for different types of phase transitions. We illustrate this with three paradigmatic examples of many body systems exhibiting symmetry breaking: the quantum Ising model, the classical q-state Potts model in two-dimensions at finite temperature and the ideal Bose gas in three-dimensions at finite temperature. This state based viewpoint on phase transitions provides a unique novel tool for studying exotic many body phenomena in quantum and classical systems.

A spectral geometric model for Compton single scatter in PET based on the single scatter simulation approximation

NASA Astrophysics Data System (ADS)

Kazantsev, I. G.; Olsen, U. L.; Poulsen, H. F.; Hansen, P. C.

2018-02-01

We investigate the idealized mathematical model of single scatter in PET for a detector system possessing excellent energy resolution. The model has the form of integral transforms estimating the distribution of photons undergoing a single Compton scattering with a certain angle. The total single scatter is interpreted as the volume integral over scatter points that constitute a rotation body with a football shape, while single scattering with a certain angle is evaluated as the surface integral over the boundary of the rotation body. The equations for total and sample single scatter calculations are derived using a single scatter simulation approximation. We show that the three-dimensional slice-by-slice filtered backprojection algorithm is applicable for scatter data inversion provided that the attenuation map is assumed to be constant. The results of the numerical experiments are presented.

ELECTRONIC SPECTRA OF AZA-AROMATICS IN POLYMER MATRICES.

DTIC Science & Technology

The absorption and fluorescence of acridine, phenazine , their cations, and phenazine -di-N-oxide were studied in polymer matrices. The correspondence...spectral properties are compared. The extent of solid solvent perturbation on spectral location and bandwidth is illustrated for acridine and phenazine

Immunohistochemical study of extracellular matrices and elastic fibers in a human sternoclavicular joint.

PubMed

Shimada, K; Takeshige, N; Moriyama, H; Miyauchi, Y; Shimada, S; Fujimaki, E

1997-12-01

In this study, we clarified the distribution of elastic and oxytalan fibers in a human sternoclavicular joint (SCJ) using a color image system and in extracellular matrices using immunoperoxidase staining. Fine elastic fibers (EFs) were scattered in the fibrous layer of the sternoclavicular disk. This articular disk was composed of a collagenous bundle on the sternum side of the articular disk in the SCJ and cellular components including connective tissue on the clavicular side of the articular disk. The thickness of the disk gradually increased from the inferior to superior portion. Collagen fibers type I, III and V and other extracellular matrices (ECMs) were detected in the hypertrophic zone in the clavicular and sternum side of the SCJ and in the connective tissue of the articulatio condylar. On the cervical surface of the articular disk, cellular activity was higher than on the sternum surface.

Limits on entanglement from rotationally invariant scattering of spin systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harshman, N. L.

2006-06-15

This paper investigates the dynamical generation of entanglement in scattering systems, in particular two spin systems that interact via rotationally invariant scattering. The spin degrees of freedom of the in states are assumed to be in unentangled, pure states, as defined by the entropy of entanglement. Because of the restriction of rotationally symmetric interactions, perfectly entangling S matrices, i.e., those that lead to a maximally entangled out state, only exist for a certain class of separable in states. Using Clebsch-Gordan coefficients for the rotation group, the scattering phases that determine the S matrix are determined for the case of spinmore » systems with {sigma}=1/2, 1, and 3/2.« less

LETTER TO THE EDITOR: Differential electron scattering from the (010) excited vibrational mode of N2O

NASA Astrophysics Data System (ADS)

Akther, P.; Johnstone, W. M.; El-Zein, A. A. A.; Campbell, L.; Teubner, P. J. O.; Brunger, M. J.; Newell, W. R.

2002-11-01

In this letter we report differential superelastic, elastic and inelastic electron scattering measurements from nitrous oxide (N2O) in its (010)* excited vibrational quantum. The incident electron energy was 2.5 eV and the scattered electron angular range was 10°- 40°. Unlike our previous results (1999 J. Phys. B: At. Mol. Opt. Phys. 32 5779) with the isoelectronic molecule carbon dioxide (CO2), where the elastic differential cross sections (DCSs) for scattering from the (010)* mode were 2.3 times larger than those for elastic scattering from the ground (000) state, in N2O the corresponding (010)* elastic cross sections are usually only a fraction of those for the ground state. To the best of our knowledge, the present data are the first DCSs which have been reported in the literature for electron scattering from an excited vibrational level of the N2O molecule.

Low energy scattering cross section ratios of 14N(p ,p ) 14N

NASA Astrophysics Data System (ADS)

deBoer, R. J.; Bardayan, D. W.; Görres, J.; LeBlanc, P. J.; Manukyan, K. V.; Moran, M. T.; Smith, K.; Tan, W.; Uberseder, E.; Wiescher, M.; Bertone, P. F.; Champagne, A. E.; Islam, M. S.

2015-04-01

Background: The slowest reaction in the first CNO cycle is 14N(p ,γ ) 15O , therefore its rate determines the overall energy production efficiency of the entire cycle. The cross section presents several strong resonance contributions, especially for the ground-state transition. Some of the properties of the corresponding levels in the 15O compound nucleus remain uncertain, which affects the uncertainty in extrapolating the capture cross section to the low energy range of astrophysical interest. Purpose: The 14N(p ,γ ) 15O cross section can be described by using the phenomenological R matrix. Over the energy range of interest, only the proton and γ -ray channels are open. Since resonance capture makes significant contributions to the 14N(p ,γ ) 15O cross section, resonant proton scattering data can be used to provide additional constraints on the R -matrix fit of the capture data. Methods: A 4 MV KN Van de Graaff accelerator was used to bombard protons onto a windowless gas target containing enriched 14N gas over the proton energy range from Ep=1.0 to 3.0 MeV. Scattered protons were detected at θlab=90 , 120∘, 135∘, 150∘, and 160∘ using ruggedized silicon detectors. In addition, a 10 MV FN Tandem Van de Graaff accelerator was used to accelerate protons onto a solid Adenine (C5H5N5 ) target, of natural isotopic abundance, evaporated onto a thin self-supporting carbon backing, over the energy range from Ep=1.8 to 4.0 MeV. Scattered protons were detected at 28 angles between θlab=30 .4∘ and 167 .7∘ by using silicon photodiode detectors. Results: Relative cross sections were extracted from both measurements. While the relative cross sections do not provide as much constraint as absolute measurements, they greatly reduce the dependence of the data on otherwise significant systematic uncertainties, which are more difficult to quantify. The data are fit simultaneously using an R -matrix analysis and level energies and proton widths are extracted. Even

Efficient nonparametric n -body force fields from machine learning

NASA Astrophysics Data System (ADS)

Glielmo, Aldo; Zeni, Claudio; De Vita, Alessandro

2018-05-01

We provide a definition and explicit expressions for n -body Gaussian process (GP) kernels, which can learn any interatomic interaction occurring in a physical system, up to n -body contributions, for any value of n . The series is complete, as it can be shown that the "universal approximator" squared exponential kernel can be written as a sum of n -body kernels. These recipes enable the choice of optimally efficient force models for each target system, as confirmed by extensive testing on various materials. We furthermore describe how the n -body kernels can be "mapped" on equivalent representations that provide database-size-independent predictions and are thus crucially more efficient. We explicitly carry out this mapping procedure for the first nontrivial (three-body) kernel of the series, and we show that this reproduces the GP-predicted forces with meV /Å accuracy while being orders of magnitude faster. These results pave the way to using novel force models (here named "M-FFs") that are computationally as fast as their corresponding standard parametrized n -body force fields, while retaining the nonparametric character, the ease of training and validation, and the accuracy of the best recently proposed machine-learning potentials.

A hypothetical learning trajectory for conceptualizing matrices as linear transformations

NASA Astrophysics Data System (ADS)

Andrews-Larson, Christine; Wawro, Megan; Zandieh, Michelle

2017-08-01

In this paper, we present a hypothetical learning trajectory (HLT) aimed at supporting students in developing flexible ways of reasoning about matrices as linear transformations in the context of introductory linear algebra. In our HLT, we highlight the integral role of the instructor in this development. Our HLT is based on the 'Italicizing N' task sequence, in which students work to generate, compose, and invert matrices that correspond to geometric transformations specified within the problem context. In particular, we describe the ways in which the students develop local transformation views of matrix multiplication (focused on individual mappings of input vectors to output vectors) and extend these local views to more global views in which matrices are conceptualized in terms of how they transform a space in a coordinated way.

An investigation of light transport through scattering bodies with non-scattering regions.

PubMed

Firbank, M; Arridge, S R; Schweiger, M; Delpy, D T

1996-04-01

Near-infra-red (NIR) spectroscopy is increasingly being used for monitoring cerebral oxygenation and haemodynamics. One current concern is the effect of the clear cerebrospinal fluid upon the distribution of light in the head. There are difficulties in modelling clear layers in scattering systems. The Monte Carlo model should handle clear regions accurately, but is too slow to be used for realistic geometries. The diffusion equation can be solved quickly for realistic geometries, but is only valid in scattering regions. In this paper we describe experiments carried out on a solid slab phantom to investigate the effect of clear regions. The experimental results were compared with the different models of light propagation. We found that the presence of a clear layer had a significant effect upon the light distribution, which was modelled correctly by Monte Carlo techniques, but not by diffusion theory. A novel approach to calculating the light transport was developed, using diffusion theory to analyze the scattering regions combined with a radiosity approach to analyze the propagation through the clear region. Results from this approach were found to agree with both the Monte Carlo and experimental data.

Medical applications of neutron inelastic scattering

NASA Astrophysics Data System (ADS)

Kehayias, Joseph J.; Banuk-Waitekus, Anathea; Valtuena, Silvia; Sheahan, Charles A.

1999-10-01

A sealed, D-T, pulsed neutron generator is used for the in vivo measurement of body carbon and oxygen by neutron inelastic scattering. The generator is operated at 10 KHz, at a neutron output of about 2 X 107 n/s/4(pi) . Gamma ray spectra are collected with two B4Ge3O12 crystal detectors. The measurements are used to measure fat and lean content and distribution in the body, with minimal radiation exposure (0.08 mSv). When combined with other measurements (such as total body potassium), this whole body scanning device provides us with the `quality of lean mass', a measurable outcome of treatments designed to improve nutritional status and function. The method is used in studies of human nutrition and for assessing the efficacy of new anti-obesity and anti-cachexia pharmaceuticals.

Improvement of Visuo-spatial Function Assessed by Raven’s Colored Progressive Matrices in Dementia with Lewy Bodies by Donepezil Treatment

PubMed Central

Yoshino, Yuta; Mori, Takaaki; Yoshida, Taku; Toyota, Yasutaka; Shimizu, Hideaki; Iga, Jun-ichi; Nishitani, Shusaku; Ueno, Shu-ichi

2017-01-01

Objective Donepezil is used to improve cognitive impairment of dementia with Lewy bodies (DLB). Visuo-spatial dysfunction is a well-known symptom of DLB. Non-verbal Raven’s Colored Progressive Matrices (RCPM) were used to assess both visual perception and reasoning ability in DLB subjects treated with donepezil. Methods Twenty-one DLB patients (mean age, 78.7±4.5 years) were enrolled. RCPM assessment was performed at the time of starting donepezil and within one year after starting donepezil. Results There were significant improvements of RCPM in the total scores between one year donepezil treatment (p=0.013), in both Set A score (p=0.002) and Set AB score (p=0.015), but trend in the Set B score (p=0.083). Conclusion Donepezil is useful for improving visuo-spatial impairment in DLB, but not for problem-solving impairment. PMID:28783933

Universality for 1d Random Band Matrices: Sigma-Model Approximation

NASA Astrophysics Data System (ADS)

Shcherbina, Mariya; Shcherbina, Tatyana

2018-02-01

The paper continues the development of the rigorous supersymmetric transfer matrix approach to the random band matrices started in (J Stat Phys 164:1233-1260, 2016; Commun Math Phys 351:1009-1044, 2017). We consider random Hermitian block band matrices consisting of W× W random Gaussian blocks (parametrized by j,k \\in Λ =[1,n]^d\\cap Z^d ) with a fixed entry's variance J_{jk}=δ _{j,k}W^{-1}+β Δ _{j,k}W^{-2} , β >0 in each block. Taking the limit W→ ∞ with fixed n and β , we derive the sigma-model approximation of the second correlation function similar to Efetov's one. Then, considering the limit β , n→ ∞, we prove that in the dimension d=1 the behaviour of the sigma-model approximation in the bulk of the spectrum, as β ≫ n , is determined by the classical Wigner-Dyson statistics.

Intrinsic character of Stokes matrices

NASA Astrophysics Data System (ADS)

Gagnon, Jean-François; Rousseau, Christiane

2017-02-01

Two germs of linear analytic differential systems x k + 1Y‧ = A (x) Y with a non-resonant irregular singularity are analytically equivalent if and only if they have the same eigenvalues and equivalent collections of Stokes matrices. The Stokes matrices are the transition matrices between sectors on which the system is analytically equivalent to its formal normal form. Each sector contains exactly one separating ray for each pair of eigenvalues. A rotation in S allows supposing that R+ lies in the intersection of two sectors. Reordering of the coordinates of Y allows ordering the real parts of the eigenvalues, thus yielding triangular Stokes matrices. However, the choice of the rotation in x is not canonical. In this paper we establish how the collection of Stokes matrices depends on this rotation, and hence on a chosen order of the projection of the eigenvalues on a line through the origin.

Synthesis and Raman scattering of GaN nanorings, nanoribbons and nanowires

NASA Astrophysics Data System (ADS)

Li, Z. J.; Chen, X. L.; Li, H. J.; Tu, Q. Y.; Yang, Z.; Xu, Y. P.; Hu, B. Q.

Low-dimensional GaN materials, including nanorings, nanoribbons and smooth nanowires have been synthesized by reacting gallium and ammonia using Ag particles as a catalyst on the substrate of MgO single crystals. They were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). EDX, XRD indicated that the low-dimensional nanomaterials were wurtzite GaN. New features are found in Raman scatterings for these low-dimensional GaN materials, which are different from the previous observations of GaN materials.

Exciton Scattering approach for conjugated macromolecules: from electronic spectra to electron-phonon coupling

NASA Astrophysics Data System (ADS)

Tretiak, Sergei

2014-03-01

The exciton scattering (ES) technique is a multiscale approach developed for efficient calculations of excited-state electronic structure and optical spectra in low-dimensional conjugated macromolecules. Within the ES method, the electronic excitations in the molecular structure are attributed to standing waves representing quantum quasi-particles (excitons), which reside on the graph. The exciton propagation on the linear segments is characterized by the exciton dispersion, whereas the exciton scattering on the branching centers is determined by the energy-dependent scattering matrices. Using these ES energetic parameters, the excitation energies are then found by solving a set of generalized ``particle in a box'' problems on the graph that represents the molecule. All parameters can be extracted from quantum-chemical computations of small molecular fragments and tabulated in the ES library for further applications. Subsequently, spectroscopic modeling for any macrostructure within considered molecular family could be performed with negligible numerical effort. The exciton scattering properties of molecular vertices can be further described by tight-binding or equivalently lattice models. The on-site energies and hopping constants are obtained from the exciton dispersion and scattering matrices. Such tight-binding model approach is particularly useful to describe the exciton-phonon coupling, energetic disorder and incoherent energy transfer in large branched conjugated molecules. Overall the ES applications accurately reproduce the optical spectra compared to the reference quantum chemistry results, and make possible to predict spectra of complex macromolecules, where conventional electronic structure calculations are unfeasible.

The Inverse of Banded Matrices

DTIC Science & Technology

2013-01-01

indexed entries all zeros. In this paper, generalizing a method of Mallik (1999) [5], we give the LU factorization and the inverse of the matrix Br,n (if it...r ≤ i ≤ r, 1 ≤ j ≤ r, with the remaining un-indexed entries all zeros. In this paper generalizing a method of Mallik (1999) [5...matrices and applications to piecewise cubic approximation, J. Comput. Appl. Math. 8 (4) (1982) 285–288. [5] R.K. Mallik , The inverse of a lower

Modal Ring Method for the Scattering of Electromagnetic Waves

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Kreider, Kevin L.

1993-01-01

The modal ring method for electromagnetic scattering from perfectly electric conducting (PEC) symmetrical bodies is presented. The scattering body is represented by a line of finite elements (triangular) on its outer surface. The infinite computational region surrounding the body is represented analytically by an eigenfunction expansion. The modal ring method effectively reduces the two dimensional scattering problem to a one-dimensional problem similar to the method of moments. The modal element method is capable of handling very high frequency scattering because it has a highly banded solution matrix.

pycola: N-body COLA method code

NASA Astrophysics Data System (ADS)

Tassev, Svetlin; Eisenstein, Daniel J.; Wandelt, Benjamin D.; Zaldarriagag, Matias

2015-09-01

pycola is a multithreaded Python/Cython N-body code, implementing the Comoving Lagrangian Acceleration (COLA) method in the temporal and spatial domains, which trades accuracy at small-scales to gain computational speed without sacrificing accuracy at large scales. This is especially useful for cheaply generating large ensembles of accurate mock halo catalogs required to study galaxy clustering and weak lensing. The COLA method achieves its speed by calculating the large-scale dynamics exactly using LPT while letting the N-body code solve for the small scales, without requiring it to capture exactly the internal dynamics of halos.

The collision singularity in a perturbed n-body problem.

NASA Technical Reports Server (NTRS)

Sperling, H. J.

1972-01-01

Collision of all bodies in a perturbed n-body problem is analyzed by an extension of the author's results for a perturbed two-body problem (1969). A procedure is set forth to prove that the absolute value of energy in a perturbed n-body system remains bounded until the moment of collision. It is shown that the characteristics of motion in both perturbed problems are basically the same.

Spin structure of the 'Forward' nucleon charge-exchange reaction n + p {yields} p + n and the deuteron charge-exchange breakup

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lyuboshitz, V. L., E-mail: Valery.Lyuboshitz@jinr.ru; Lyuboshitz, V. V.

2011-02-15

The structure of the nucleon charge-exchange process n + p {yields} p + n is investigated basing on the isotopic invariance of the nucleon-nucleon scattering. Using the operator of permutation of the spin projections of the neutron and proton, the connection between the spin matrices, describing the amplitude of the nucleon charge-exchange process at zero angle and the amplitude of the elastic scattering of the neutron on the proton in the 'backward' direction, has been considered. Due to the optical theorem, the spin-independent part of the differential cross section of the process n + p {yields} p + n atmore » zero angle for unpolarized particles is expressed through the difference of total cross sections of unpolarized proton-proton and neutron-proton scattering. Meantime, the spin-dependent part of this cross section is proportional to the differential cross section of the deuteron charge-exchange breakup d + p {yields} (pp) + n at zero angle at the deuteron momentum k{sub d} = 2 k{sub n} (k{sub n} is the initial neutron momentum). Analysis shows that, assuming the real part of the spin-independent term of the 'forward' amplitude of the process n + p {yields} p + n to be smaller or of the same order as compared with the imaginary part, in the wide range of neutron laboratory momenta k{sub n} > 700 MeV/c the main contribution into the differential cross section of the process n + p {yields} p + n at zero angle is provided namely by the spin-dependent term.« less

Location Prediction Based on Transition Probability Matrices Constructing from Sequential Rules for Spatial-Temporal K-Anonymity Dataset

PubMed Central

Liu, Zhao; Zhu, Yunhong; Wu, Chenxue

2016-01-01

Spatial-temporal k-anonymity has become a mainstream approach among techniques for protection of users’ privacy in location-based services (LBS) applications, and has been applied to several variants such as LBS snapshot queries and continuous queries. Analyzing large-scale spatial-temporal anonymity sets may benefit several LBS applications. In this paper, we propose two location prediction methods based on transition probability matrices constructing from sequential rules for spatial-temporal k-anonymity dataset. First, we define single-step sequential rules mined from sequential spatial-temporal k-anonymity datasets generated from continuous LBS queries for multiple users. We then construct transition probability matrices from mined single-step sequential rules, and normalize the transition probabilities in the transition matrices. Next, we regard a mobility model for an LBS requester as a stationary stochastic process and compute the n-step transition probability matrices by raising the normalized transition probability matrices to the power n. Furthermore, we propose two location prediction methods: rough prediction and accurate prediction. The former achieves the probabilities of arriving at target locations along simple paths those include only current locations, target locations and transition steps. By iteratively combining the probabilities for simple paths with n steps and the probabilities for detailed paths with n-1 steps, the latter method calculates transition probabilities for detailed paths with n steps from current locations to target locations. Finally, we conduct extensive experiments, and correctness and flexibility of our proposed algorithm have been verified. PMID:27508502

Radiation and scattering from bodies of translation. Volume 2: User's manual, computer program documentation

NASA Astrophysics Data System (ADS)

Medgyesi-Mitschang, L. N.; Putnam, J. M.

1980-04-01

A hierarchy of computer programs implementing the method of moments for bodies of translation (MM/BOT) is described. The algorithm treats the far-field radiation and scattering from finite-length open cylinders of arbitrary cross section as well as the near fields and aperture-coupled fields for rectangular apertures on such bodies. The theoretical development underlying the algorithm is described in Volume 1. The structure of the computer algorithm is such that no a priori knowledge of the method of moments technique or detailed FORTRAN experience are presupposed for the user. A set of carefully drawn example problems illustrates all the options of the algorithm. For more detailed understanding of the workings of the codes, special cross referencing to the equations in Volume 1 is provided. For additional clarity, comment statements are liberally interspersed in the code listings, summarized in the present volume.

Yang Baxter and anisotropic sigma and lambda models, cyclic RG and exact S-matrices

NASA Astrophysics Data System (ADS)

Appadu, Calan; Hollowood, Timothy J.; Price, Dafydd; Thompson, Daniel C.

2017-09-01

Integrable deformation of SU(2) sigma and lambda models are considered at the classical and quantum levels. These are the Yang-Baxter and XXZ-type anisotropic deformations. The XXZ type deformations are UV safe in one regime, while in another regime, like the Yang-Baxter deformations, they exhibit cyclic RG behaviour. The associ-ated affine quantum group symmetry, realized classically at the Poisson bracket level, has q a complex phase in the UV safe regime and q real in the cyclic RG regime, where q is an RG invariant. Based on the symmetries and RG flow we propose exact factorizable S-matrices to describe the scattering of states in the lambda models, from which the sigma models follow by taking a limit and non-abelian T-duality. In the cyclic RG regimes, the S-matrices are periodic functions of rapidity, at large rapidity, and in the Yang-Baxter case violate parity.

Properties of Tangential and Cyclic Polygons: An Application of Circulant Matrices

ERIC Educational Resources Information Center

Leung, Allen; Lopez-Real, Francis

2003-01-01

In this paper, the properties of tangential and cyclic polygons proposed by Lopez-Real are proved rigorously using the theory of circulant matrices. In particular, the concepts of slippable tangential polygons and conformable cyclic polygons are defined. It is shown that an n-sided tangential (or cyclic) polygon P[subscript n] with n even is…

Symmetries in N-body problem

NASA Astrophysics Data System (ADS)

Xia, Zhihong

2008-09-01

The purpose of this note is to introduce some of the basic techniques in group theory to the study the symmetries of the Newtonian n-body problem. The main tool is the representations of finite groups.

Ultrafast Independent N-H and N-C Bond Deformation Investigated with Resonant Inelastic X-Ray Scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eckert, Sebastian; Norell, Jesper; Miedema, Piter S.

Here, the femtosecond excited-state dynamics following resonant photoexcitation enable the selective deformation of N-H and N-C chemical bonds in 2-thiopyridone in aqueous solution with optical or X-ray pulses. In combination with multiconfigurational quantum-chemical calculations, the orbital-specific electronic structure and its ultrafast dynamics accessed with resonant inelastic X-ray scattering at the N 1s level using synchrotron radiation and the soft X-ray free-electron laser LCLS provide direct evidence for this controlled photoinduced molecular deformation and its ultrashort timescale.

Ultrafast Independent N-H and N-C Bond Deformation Investigated with Resonant Inelastic X-Ray Scattering

DOE PAGES

Eckert, Sebastian; Norell, Jesper; Miedema, Piter S.; ...

2017-04-04

Here, the femtosecond excited-state dynamics following resonant photoexcitation enable the selective deformation of N-H and N-C chemical bonds in 2-thiopyridone in aqueous solution with optical or X-ray pulses. In combination with multiconfigurational quantum-chemical calculations, the orbital-specific electronic structure and its ultrafast dynamics accessed with resonant inelastic X-ray scattering at the N 1s level using synchrotron radiation and the soft X-ray free-electron laser LCLS provide direct evidence for this controlled photoinduced molecular deformation and its ultrashort timescale.

The influence of the PCF scattering on the electrical properties of the AlGaN/AlN/GaN HEMTs after the Si3N4 surface passivation

NASA Astrophysics Data System (ADS)

Fu, Chen; Lin, Zhaojun; Cui, Peng; Lv, Yuanjie; Zhou, Yang; Dai, Gang; Luan, Chongbiao; Liu, Huan; Cheng, Aijie

2018-04-01

In this paper, the detailed device characteristics were investigated both before and after the Si3N4 passivation grown by plasma-enhanced chemical vapor deposition (PECVD). Better transport properties have been observed for the passivated devices compared with the same ones before passivation. The strain variation and the influence of the scattering mechanisms were analyzed and studied. The calculated results show that the non-uniform distribution of the additional polarization charges at the AlGaN/AlN/GaN interfaces has been weakened by the deposition of the Si3N4 layer. The numerical rise of the two-dimensional electron gas (2DEG) electron mobility and the decrease of the measured R on- A values were in a good consistency, and the weakening of the polarization Coulomb field (PCF) scattering after the passivation process is considered to be the main cause of these phenomena.

Raman scattering by H2 and N2 in the atmospheres of exoplanets

NASA Astrophysics Data System (ADS)

Oklopcic, Antonija; Hirata, Christopher M.; Heng, Kevin

2016-06-01

Rayleigh scattering is an important source of opacity in the atmospheres of exoplanets at short optical and near-UV wavelengths. Raman scattering is an inelastic process related to Rayleigh scattering, but with a weaker cross section. We analyze the signatures of Raman scattering imprinted in the reflected light and the geometric albedo of exoplanets. Raman scattering causes filling-in of absorption lines in the incident spectrum, thus producing sharp enhancements in the geometric albedo. It also shifts the wavelengths of spectral features in the reflected light causing the Raman ghost lines. Observing the albedo enhancements could be used to measure the column density of the scattering molecule and provide constrains on the presence of clouds and hazes in the atmosphere. Observing the Raman ghost lines could be used to spectroscopically identify the main scatterer in the atmosphere -- molecules like H2 or N2 which do not show prominent spectral signatures in the optical wavelength range. If detected, ghost lines could also provide information about the temperature of the atmosphere. Here we present how these signatures of Raman scattering in hydrogen- and nitrogen-dominated atmospheres can be used as probes of atmospheric pressure, temperature and composition. We analyze the feasibility of detecting these features in the albedo spectra of nearby exoplanets with the existing and future observational facilities.

Scattering Of Nonplanar Acoustic Waves

NASA Technical Reports Server (NTRS)

Gillman, Judith M.; Farassat, F.; Myers, M. K.

1995-01-01

Report presents theoretical study of scattering of nonplanar acoustic waves by rigid bodies. Study performed as part of effort to develop means of predicting scattering, from aircraft fuselages, of noise made by rotating blades. Basic approach was to model acoustic scattering by use of boundary integral equation to solve equation by the Galerkin method.

Genetic code, hamming distance and stochastic matrices.

PubMed

He, Matthew X; Petoukhov, Sergei V; Ricci, Paolo E

2004-09-01

In this paper we use the Gray code representation of the genetic code C=00, U=10, G=11 and A=01 (C pairs with G, A pairs with U) to generate a sequence of genetic code-based matrices. In connection with these code-based matrices, we use the Hamming distance to generate a sequence of numerical matrices. We then further investigate the properties of the numerical matrices and show that they are doubly stochastic and symmetric. We determine the frequency distributions of the Hamming distances, building blocks of the matrices, decomposition and iterations of matrices. We present an explicit decomposition formula for the genetic code-based matrix in terms of permutation matrices, which provides a hypercube representation of the genetic code. It is also observed that there is a Hamiltonian cycle in a genetic code-based hypercube.

Modal ring method for the scattering of sound

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Kreider, Kevin L.

1993-01-01

The modal element method for acoustic scattering can be simplified when the scattering body is rigid. In this simplified method, called the modal ring method, the scattering body is represented by a ring of triangular finite elements forming the outer surface. The acoustic pressure is calculated at the element nodes. The pressure in the infinite computational region surrounding the body is represented analytically by an eigenfunction expansion. The two solution forms are coupled by the continuity of pressure and velocity on the body surface. The modal ring method effectively reduces the two-dimensional scattering problem to a one-dimensional problem capable of handling very high frequency scattering. In contrast to the boundary element method or the method of moments, which perform a similar reduction in problem dimension, the model line method has the added advantage of having a highly banded solution matrix requiring considerably less computer storage. The method shows excellent agreement with analytic results for scattering from rigid circular cylinders over a wide frequency range (1 is equal to or less than ka is less than or equal to 100) in the near and far fields.

Kaon-nucleus scattering

NASA Technical Reports Server (NTRS)

Hong, Byungsik; Maung, Khin Maung; Wilson, John W.; Buck, Warren W.

1989-01-01

The derivations of the Lippmann-Schwinger equation and Watson multiple scattering are given. A simple optical potential is found to be the first term of that series. The number density distribution models of the nucleus, harmonic well, and Woods-Saxon are used without t-matrix taken from the scattering experiments. The parameterized two-body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to the imaginary part of the forward elastic scattering amplitude, are presented. The eikonal approximation was chosen as our solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

Ab initio many-body calculations of nucleon scattering on ^16O

NASA Astrophysics Data System (ADS)

Navratil, Petr; Quaglioni, Sofia; Roth, Robert

2008-10-01

We develop a new ab initio many-body approachootnotetextS. Quaglioni and P. Navratil, arXiv:0804.1560. capable of describing simultaneously both bound and scattering states in light nuclei, by combining the resonating-group methodootnotetextY. C. Tang et al., Phys. Rep. 47, 167 (1978); K. Langanke and H. Friedrich, Advances in Nuclear Physics, Plenum, New York, 1987. with the ab initio no-core shell model (NCSM).ootnotetextP. Navratil, J. P. Vary, and B. R. Barrett, Phys. Rev. Lett. 84, 5728 (2000); Phys. Rev. C 62, 054311 (2000). In this way, we complement a microscopic-cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, while preserving Pauli principle and translational symmetry. We will present results for low-energy nucleon scattering on ^16O and for A=17 bound states obtained using realistic nucleon-nucleon potentials. The ^16O wave functions are calculated within the importance-truncated NCSMootnotetextR. Roth and P. Navratil, Phys. Rev. Lett. 99, 092501 (2007). that allows the use of model spaces up to 18φ and ultimately enables to reach convergence of phase-shifts and other observables. Prepared by LLNL under Contract DE-AC52-07NA27344. Support from the U.S. DOE/SC/NP (Work Proposal No. SCW0498), and from the U. S. Department of Energy Grant DE-FC02-07ER41457 is acknowledged.

Application of the weighted total field-scattering field technique to 3D-PSTD light scattering model

NASA Astrophysics Data System (ADS)

Hu, Shuai; Gao, Taichang; Liu, Lei; Li, Hao; Chen, Ming; Yang, Bo

2018-04-01

PSTD (Pseudo Spectral Time Domain) is an excellent model for the light scattering simulation of nonspherical aerosol particles. However, due to the particularity of its discretization form of the Maxwell's equations, the traditional Total Field/Scattering Field (TF/SF) technique for FDTD (Finite Differential Time Domain) is not applicable to PSTD, and the time-consuming pure scattering field technique is mainly applied to introduce the incident wave. To this end, the weighted TF/SF technique proposed by X. Gao is generalized and applied to the 3D-PSTD scattering model. Using this technique, the incident light can be effectively introduced by modifying the electromagnetic components in an inserted connecting region between the total field and the scattering field region with incident terms, where the incident terms are obtained by weighting the incident field by a window function. To optimally determine the thickness of connection region and the window function type for PSTD calculations, their influence on the modeling accuracy is firstly analyzed. To further verify the effectiveness and advantages of the weighted TF/SF technique, the improved PSTD model is validated against the PSTD model equipped with pure scattering field technique in both calculation accuracy and efficiency. The results show that, the performance of PSTD seems to be not sensitive to variation of window functions. The number of the connection layer required decreases with the increasing of spatial resolution, where for spatial resolution of 24 grids per wavelength, a 6-layer region is thick enough. The scattering phase matrices and integral scattering parameters obtained by the improved PSTD show an excellent consistency with those well-tested models for spherical and nonspherical particles, illustrating that the weighted TF/SF technique can introduce the incident precisely. The weighted TF/SF technique shows higher computational efficiency than pure scattering technique.

Three-body unitarity with isobars revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mai, M.; Hu, B.; Döring, M.

The particle exchange model of hadron interactions can be used to describe three-body scattering under the isobar assumption. Here, we start from the 3->3 scattering amplitude for spinless particles, which contains an isobar-spectator scattering amplitude. Using a Bethe-Salpeter Ansatz for the latter, we derive a relativistic three-dimensional scattering equation that manifestly fulfills three-body unitarity and two-body unitarity for the sub-amplitudes. Furthermore, this property holds for energies above breakup and also in the presence of resonances in the sub-amplitudes.

Three-body unitarity with isobars revisited

DOE PAGES

Mai, M.; Hu, B.; Döring, M.; ...

2017-09-08

The particle exchange model of hadron interactions can be used to describe three-body scattering under the isobar assumption. Here, we start from the 3->3 scattering amplitude for spinless particles, which contains an isobar-spectator scattering amplitude. Using a Bethe-Salpeter Ansatz for the latter, we derive a relativistic three-dimensional scattering equation that manifestly fulfills three-body unitarity and two-body unitarity for the sub-amplitudes. Furthermore, this property holds for energies above breakup and also in the presence of resonances in the sub-amplitudes.

Light scattering by a nematic liquid crystal droplet: Wentzel–Kramers–Brillouin approximation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loiko, V. A., E-mail: loiko@dragon.bas-net.by; Konkolovich, A. V.; Miskevich, A. A.

2016-01-15

Light scattering by an optically anisotropic liquid crystal (LC) droplet of a nematic in an isotropic polymer matrix is considered in the Wentzel–Kramers–Brillouin (WKB) approximation. General relations are obtained for elements of the amplitude matrix of light scattering by a droplet of arbitrary shape and for the structure of the director field. Analytic expressions for the amplitude matrices are derived for spherical LC droplets with a uniformly oriented structure of local optical axes for strictly forward and strictly backward scattering. The efficiency factors of extinction and backward scattering for a spherical nonabsorbing LC droplet depending on the LC optical anisotropy,more » refractive index of the polymer, illumination conditions, and orientation of the optical axis of the droplet are analyzed. Verification of the obtained solutions has been performed.« less

Sound scattering by several zooplankton groups. I. Experimental determination of dominant scattering mechanisms.

PubMed

Stanton, T K; Chu, D; Wiebe, P H; Martin, L V; Eastwood, R L

1998-01-01

The acoustic scattering properties of live individual zooplankton from several gross anatomical groups have been investigated. The groups involve (1) euphausiids (Meganyctiphanes norvegica) whose bodies behave acoustically as a fluid material, (2) gastropods (Limacina retroversa) whose bodies include a hard elastic shell, and (3) siphonophores (Agalma okeni or elegans and Nanomia cara) whose bodies contain a gas inclusion (pneumatophore). The animals were collected from ocean waters off New England (Slope Water, Georges Bank, and the Gulf of Maine). The scattering properties were measured over parts or all of the frequency range 50 kHz to 1 MHz in a laboratory-style pulse-echo setup in a large tank at sea using live fresh specimens. Individual echoes as well as averages and ping-to-ping fluctuations of repeated echoes were studied. The material type of each group is shown to strongly affect both the overall echo level and pattern of the target strength versus frequency plots. In this first article of a two-part series, the dominant scattering mechanisms of the three animal types are determined principally by examining the structure of both the frequency spectra of individual broadband echoes and the compressed pulse (time series) output. Other information is also used involving the effect on overall levels due to (1) animal orientation and (2) tissue in animals having a gas inclusion (siphonophores). The results of this first paper show that (1) the euphausiids behave as weakly scattering fluid bodies and there are major contributions from at least two parts of the body to the echo (the number of contributions depends upon angle of orientation and shape), (2) the gastropods produce echoes from the front interface and possibly from a slow-traveling circumferential (Lamb) wave, and (3) the gas inclusion of the siphonophore dominates the echoes, but the tissue plays a role in the scattering and is especially important when analyzing echoes from individual animals on a

Improved scatter correction using adaptive scatter kernel superposition

NASA Astrophysics Data System (ADS)

Sun, M.; Star-Lack, J. M.

2010-11-01

Accurate scatter correction is required to produce high-quality reconstructions of x-ray cone-beam computed tomography (CBCT) scans. This paper describes new scatter kernel superposition (SKS) algorithms for deconvolving scatter from projection data. The algorithms are designed to improve upon the conventional approach whose accuracy is limited by the use of symmetric kernels that characterize the scatter properties of uniform slabs. To model scatter transport in more realistic objects, nonstationary kernels, whose shapes adapt to local thickness variations in the projection data, are proposed. Two methods are introduced: (1) adaptive scatter kernel superposition (ASKS) requiring spatial domain convolutions and (2) fast adaptive scatter kernel superposition (fASKS) where, through a linearity approximation, convolution is efficiently performed in Fourier space. The conventional SKS algorithm, ASKS, and fASKS, were tested with Monte Carlo simulations and with phantom data acquired on a table-top CBCT system matching the Varian On-Board Imager (OBI). All three models accounted for scatter point-spread broadening due to object thickening, object edge effects, detector scatter properties and an anti-scatter grid. Hounsfield unit (HU) errors in reconstructions of a large pelvis phantom with a measured maximum scatter-to-primary ratio over 200% were reduced from -90 ± 58 HU (mean ± standard deviation) with no scatter correction to 53 ± 82 HU with SKS, to 19 ± 25 HU with fASKS and to 13 ± 21 HU with ASKS. HU accuracies and measured contrast were similarly improved in reconstructions of a body-sized elliptical Catphan phantom. The results show that the adaptive SKS methods offer significant advantages over the conventional scatter deconvolution technique.

Kaon-nucleus scattering

NASA Technical Reports Server (NTRS)

Hong, Byungsik; Buck, Warren W.; Maung, Khin M.

1989-01-01

Two kinds of number density distributions of the nucleus, harmonic well and Woods-Saxon models, are used with the t-matrix that is taken from the scattering experiments to find a simple optical potential. The parameterized two body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to imaginary part of the forward elastic scattering amplitude, are shown. The eikonal approximation was chosen as the solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Escobar-Cerezo, J.; Palmer, C.; Muñoz, O.

The effect of internal inhomogeneities and surface roughness on the scattering behavior of large cosmic dust particles is studied by comparing model simulations with laboratory measurements. The present work shows the results of an attempt to model a dust sample measured in the laboratory with simulations performed by a ray-optics model code. We consider this dust sample as a good analogue for interplanetary and interstellar dust as it shares its refractive index with known materials in these media. Several sensitivity tests have been performed for both structural cases (internal inclusions and surface roughness). Three different samples have been selected tomore » mimic inclusion/coating inhomogeneities: two measured scattering matrices of hematite and white clay, and a simulated matrix for water ice. These three matrices are selected to cover a wide range of imaginary refractive indices. The selection of these materials also seeks to study astrophysical environments of interest such as Mars, where hematite and clays have been detected, and comets. Based on the results of the sensitivity tests shown in this work, we perform calculations for a size distribution of a silicate-type host particle model with inclusions and surface roughness to reproduce the experimental measurements of a dust sample. The model fits the measurements quite well, proving that surface roughness and internal structure play a role in the scattering pattern of irregular cosmic dust particles.« less

SAXS Combined with UV-vis Spectroscopy and QELS: Accurate Characterization of Silver Sols Synthesized in Polymer Matrices.

PubMed

Bulavin, Leonid; Kutsevol, Nataliya; Chumachenko, Vasyl; Soloviov, Dmytro; Kuklin, Alexander; Marynin, Andrii

2016-12-01

The present work demonstrates a validation of small-angle X-ray scattering (SAXS) combining with ultra violet and visible (UV-vis) spectroscopy and quasi-elastic light scattering (QELS) analysis for characterization of silver sols synthesized in polymer matrices. Polymer matrix internal structure and polymer chemical nature actually controlled the sol size characteristics. It was shown that for precise analysis of nanoparticle size distribution these techniques should be used simultaneously. All applied methods were in good agreement for the characterization of size distribution of small particles (less than 60 nm) in the sols. Some deviations of the theoretical curves from the experimental ones were observed. The most probable cause is that nanoparticles were not entirely spherical in form.

Hip-hop solutions of the 2N-body problem

NASA Astrophysics Data System (ADS)

Barrabés, Esther; Cors, Josep Maria; Pinyol, Conxita; Soler, Jaume

2006-05-01

Hip-hop solutions of the 2N-body problem with equal masses are shown to exist using an analytic continuation argument. These solutions are close to planar regular 2N-gon relative equilibria with small vertical oscillations. For fixed N, an infinity of these solutions are three-dimensional choreographies, with all the bodies moving along the same closed curve in the inertial frame.

Preparation and evaluation of silicon nitride matrices for silicon nitride-SiC fiber composites. M.S. Thesis Final Technical Report

NASA Technical Reports Server (NTRS)

Axelson, Scott R.

1988-01-01

Continuous silicon carbide (SiC) fiber was added to three types of silicon nitride (Si3N4) matrices. Efforts were aimed at producing a dense Si3N4 matrix from reaction-bonded silicon nitride (RBSN) by hot-isostatic-pressing (HIP) and pressureless sintering, and from Si3N4 powder by hot-pressing. The sintering additives utilized were chosen to allow for densification, while not causing severe degradation of the fiber. The ceramic microstructures were evaluated using scanning optical microscopy. Vickers indentation was used to determine the microhardness and fracture toughness values of the matrices. The RBSN matrices in this study did not reach more than 80 percent of theoretical density after sintering at various temperatures, pressures, and additive levels. Hot-pressing Si3N4 powder produced the highest density matrices; hardness and toughness values were within an order of magnitude of the best literature values. The best sintering aid composition chosen included Y2O3, SiO2, and Al2O3 or AlN. Photomicrographs demonstrate a significant reduction of fiber attack by this additive composition.

Million-body star cluster simulations: comparisons between Monte Carlo and direct N-body

NASA Astrophysics Data System (ADS)

Rodriguez, Carl L.; Morscher, Meagan; Wang, Long; Chatterjee, Sourav; Rasio, Frederic A.; Spurzem, Rainer

2016-12-01

We present the first detailed comparison between million-body globular cluster simulations computed with a Hénon-type Monte Carlo code, CMC, and a direct N-body code, NBODY6++GPU. Both simulations start from an identical cluster model with 106 particles, and include all of the relevant physics needed to treat the system in a highly realistic way. With the two codes `frozen' (no fine-tuning of any free parameters or internal algorithms of the codes) we find good agreement in the overall evolution of the two models. Furthermore, we find that in both models, large numbers of stellar-mass black holes (>1000) are retained for 12 Gyr. Thus, the very accurate direct N-body approach confirms recent predictions that black holes can be retained in present-day, old globular clusters. We find only minor disagreements between the two models and attribute these to the small-N dynamics driving the evolution of the cluster core for which the Monte Carlo assumptions are less ideal. Based on the overwhelming general agreement between the two models computed using these vastly different techniques, we conclude that our Monte Carlo approach, which is more approximate, but dramatically faster compared to the direct N-body, is capable of producing an accurate description of the long-term evolution of massive globular clusters even when the clusters contain large populations of stellar-mass black holes.

Symmetry considerations in the scattering of identical composite bodies

NASA Technical Reports Server (NTRS)

Norbury, J. W.; Townsend, L. W.; Deutchman, P. A.

1986-01-01

Previous studies of the interactions between composite particles were extended to the case in which the composites are identical. The form of the total interaction potential matrix elements was obtained, and guidelines for their explicit evaluation were given. For the case of elastic scattering of identical composites, the matrix element approach was shown to be equivalent to the scattering amplitude method.

Quantization of an electromagnetic field in two-dimensional photonic structures based on the scattering matrix formalism ( S-quantization)

NASA Astrophysics Data System (ADS)

Ivanov, K. A.; Nikolaev, V. V.; Gubaydullin, A. R.; Kaliteevski, M. A.

2017-10-01

Based on the scattering matrix formalism, we have developed a method of quantization of an electromagnetic field in two-dimensional photonic nanostructures ( S-quantization in the two-dimensional case). In this method, the fields at the boundaries of the quantization box are expanded into a Fourier series and are related with each other by the scattering matrix of the system, which is the product of matrices describing the propagation of plane waves in empty regions of the quantization box and the scattering matrix of the photonic structure (or an arbitrary inhomogeneity). The quantization condition (similarly to the onedimensional case) is formulated as follows: the eigenvalues of the scattering matrix are equal to unity, which corresponds to the fact that the set of waves that are incident on the structure (components of the expansion into the Fourier series) is equal to the set of waves that travel away from the structure (outgoing waves). The coefficients of the matrix of scattering through the inhomogeneous structure have been calculated using the following procedure: the structure is divided into parallel layers such that the permittivity in each layer varies only along the axis that is perpendicular to the layers. Using the Fourier transform, the Maxwell equations have been written in the form of a matrix that relates the Fourier components of the electric field at the boundaries of neighboring layers. The product of these matrices is the transfer matrix in the basis of the Fourier components of the electric field. Represented in a block form, it is composed by matrices that contain the reflection and transmission coefficients for the Fourier components of the field, which, in turn, constitute the scattering matrix. The developed method considerably simplifies the calculation scheme for the analysis of the behavior of the electromagnetic field in structures with a two-dimensional inhomogeneity. In addition, this method makes it possible to obviate

Light Scattering by Gaussian Particles: A Solution with Finite-Difference Time Domain Technique

NASA Technical Reports Server (NTRS)

Sun, W.; Nousiainen, T.; Fu, Q.; Loeb, N. G.; Videen, G.; Muinonen, K.

2003-01-01

The understanding of single-scattering properties of complex ice crystals has significance in atmospheric radiative transfer and remote-sensing applications. In this work, light scattering by irregularly shaped Gaussian ice crystals is studied with the finite-difference time-domain (FDTD) technique. For given sample particle shapes and size parameters in the resonance region, the scattering phase matrices and asymmetry factors are calculated. It is found that the deformation of the particle surface can significantly smooth the scattering phase functions and slightly reduce the asymmetry factors. The polarization properties of irregular ice crystals are also significantly different from those of spherical cloud particles. These FDTD results could provide a reference for approximate light-scattering models developed for irregular particle shapes and can have potential applications in developing a much simpler practical light scattering model for ice clouds angular-distribution models and for remote sensing of ice clouds and aerosols using polarized light. (copyright) 2003 Elsevier Science Ltd. All rights reserved.

NDMA formation kinetics from three pharmaceuticals in four water matrices.

PubMed

Shen, Ruqiao; Andrews, Susan A

2011-11-01

N, N-nitrosodimethylamine (NDMA) is an emerging disinfection by-product (DBP) that has been widely detected in many drinking water systems and commonly associated with the chloramine disinfection process. Some amine-based pharmaceuticals have been demonstrated to form NDMA during chloramination, but studies regarding the reaction kinetics are largely lacking. This study investigates the NDMA formation kinetics from ranitidine, chlorphenamine, and doxylamine under practical chloramine disinfection conditions. The formation profile was monitored in both lab-grade water and real water matrices, and a statistical model is proposed to describe and predict the NDMA formation from selected pharmaceuticals in various water matrices. The results indicate the significant impact of water matrix components and reaction time on the NDMA formation from selected pharmaceuticals, and provide fresh insights on the estimation of ultimate NDMA formation potential from pharmaceutical precursors. Copyright © 2011 Elsevier Ltd. All rights reserved.

Coupled-channel model for K ¯ N scattering in the resonant region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernández-Ramírez, Cesar; Danilkin, Igor V.; Manley, D. Mark

2016-02-18

Here, we present a unitary multichannel model formore » $$\\bar{K}$$N scattering in the resonance region that fulfills unitarity. It has the correct analytical properties for the amplitudes once they are extended to the complex-$s$ plane and the partial waves have the right threshold behavior. In order to determine the parameters of the model, we have fitted single-energy partial waves up to J = 7/2 and up to 2.15 GeV of energy in the center-of-mass reference frame obtaining the poles of the Λ* and Σ* resonances, which are compared to previous analyses. Furthermore, we provide the most comprehensive picture of the S = –1 hyperon spectrum to date. Here, important differences are found between the available analyses making the gathering of further experimental information on $$\\bar{K}$$N scattering mandatory to make progress in the assessment of the hyperon spectrum.« less

Miscellaneous methods for measuring matric or water potential

USGS Publications Warehouse

Scanlon, Bridget R.; Andraski, Brian J.; Bilskie, Jim; Dane, Jacob H.; Topp, G. Clarke

2002-01-01

A variety of techniques to measure matric potential or water potential in the laboratory and in the field are described in this section. The techniques described herein require equilibration of some medium whose matric or water potential can be determined from previous calibration or can be measured directly. Under equilibrium conditions the matric or water potential of the medium is equal to that of the soil. The techniques can be divided into: (i) those that measure matric potential and (ii) those that measure water potential (sum of matric and osmotic potentials). Matric potential is determined when the sensor matrix is in direct contact with the soil, so salts are free to diffuse in or out of the sensor matrix, and the equilibrium measurement therefore reflects matric forces acting on the water. Water potential is determined when the sensor is separated from the soil by a vapor gap, so salts are not free to move in or out of the sensor, and the equilibrium measurement reflects the sum of the matric and osmotic forces acting on the water.Seven different techniques are described in this section. Those that measure matric potential include (i) heat dissipation sensors, (ii) electrical resistance sensors, (iii) frequency domain and time domain sensors, and (iv) electro-optical switches. A method that can be used to measure matric potential or water potential is the (v) filter paper method. Techniques that measure water potential include (vi) the Dew Point Potentiameter (Decagon Devices, Inc., Pullman, WA1) (water activity meter) and (vii) vapor equilibration.The first four techniques are electronically based methods for measuring matric potential. Heat dissipation sensors and electrical resistance sensors infer matric potential from previously determined calibration relations between sensor heat dissipation or electrical resistance and matric potential. Frequency-domain and timedomain matric potential sensors measure water content, which is related to matric

Complex symmetric matrices with strongly stable iterates

NASA Technical Reports Server (NTRS)

Tadmor, E.

1985-01-01

Complex-valued symmetric matrices are studied. A simple expression for the spectral norm of such matrices is obtained, by utilizing a unitarily congruent invariant form. A sharp criterion is provided for identifying those symmetric matrices whose spectral norm is not exceeding one: such strongly stable matrices are usually sought in connection with convergent difference approximations to partial differential equations. As an example, the derived criterion is applied to conclude the strong stability of a Lax-Wendroff scheme.

Chemiluminescence in cryogenic matrices

NASA Astrophysics Data System (ADS)

Lotnik, S. V.; Kazakov, Valeri P.

1989-04-01

The literature data on chemiluminescence (CL) in cryogenic matrices have been classified and correlated for the first time. The role of studies on phosphorescence and CL at low temperatures in the development of cryochemistry is shown. The features of low-temperature CL in matrices of nitrogen and inert gases (fine structure of spectra, matrix effects) and the data on the mobility and reactivity of atoms and radicals at very low temperatures are examined. The trends in the development of studies on CL in cryogenic matrices, such as the search for systems involving polyatomic molecules and extending the forms of CL reactions, are followed. The reactions of active nitrogen with hydrocarbons that are accompanied by light emission and CL in the oxidation of carbenes at T >= 77 K are examined. The bibliography includes 112 references.

Electron mobility of two-dimensional electron gas in InGaN heterostructures: Effects of alloy disorder and random dipole scatterings

NASA Astrophysics Data System (ADS)

Hoshino, Tomoki; Mori, Nobuya

2018-04-01

InGaN has a smaller electron effective mass and is expected to be used as a channel material for high-electron-mobility transistors. However, it is an alloy semiconductor with a random distribution of atoms, which introduces additional scattering mechanisms: alloy disorder and random dipole scatterings. In this work, we calculate the electron mobility in InGaN- and GaN-channel high-electron-mobility transistors (HEMTs) while taking into account acoustic deformation potential, polar optical phonon, alloy disorder, and random dipole scatterings. For InGaN-channel HEMTs, we find that not only alloy disorder but also random dipole scattering has a strong impact on the electron mobility and it significantly decreases as the In mole fraction of the channel increases. Our calculation also shows that the channel thickness w dependence of the mobility is rather weak when w > 1 nm for In0.1Ga0.9N-channel HEMTs.

Equiangular tight frames and unistochastic matrices

NASA Astrophysics Data System (ADS)

Goyeneche, Dardo; Turek, Ondřej

2017-06-01

We demonstrate that a complex equiangular tight frame composed of N vectors in dimension d, denoted ETF (d, N), exists if and only if a certain bistochastic matrix, univocally determined by N and d, belongs to a special class of unistochastic matrices. This connection allows us to find new complex ETFs in infinitely many dimensions and to derive a method to introduce non-trivial free parameters in ETFs. We present an explicit six-parametric family of complex ETF(6,16), which defines a family of symmetric POVMs. Minimal and maximal possible average entanglement of the vectors within this qubit-qutrit family are described. Furthermore, we propose an efficient numerical procedure to compute the unitary matrix underlying a unistochastic matrix, which we apply to find all existing classes of complex ETFs containing up to 20 vectors.

Cosmological N-body Simulation

NASA Astrophysics Data System (ADS)

Lake, George

1994-05-01

.90ex> }}} The ``N'' in N-body calculations has doubled every year for the last two decades. To continue this trend, the UW N-body group is working on algorithms for the fast evaluation of gravitational forces on parallel computers and establishing rigorous standards for the computations. In these algorithms, the computational cost per time step is ~ 10(3) pairwise forces per particle. A new adaptive time integrator enables us to perform high quality integrations that are fully temporally and spatially adaptive. SPH--smoothed particle hydrodynamics will be added to simulate the effects of dissipating gas and magnetic fields. The importance of these calculations is two-fold. First, they determine the nonlinear consequences of theories for the structure of the Universe. Second, they are essential for the interpretation of observations. Every galaxy has six coordinates of velocity and position. Observations determine two sky coordinates and a line of sight velocity that bundles universal expansion (distance) together with a random velocity created by the mass distribution. Simulations are needed to determine the underlying structure and masses. The importance of simulations has moved from ex post facto explanation to an integral part of planning large observational programs. I will show why high quality simulations with ``large N'' are essential to accomplish our scientific goals. This year, our simulations have N >~ 10(7) . This is sufficient to tackle some niche problems, but well short of our 5 year goal--simulating The Sloan Digital Sky Survey using a few Billion particles (a Teraflop-year simulation). Extrapolating past trends, we would have to ``wait'' 7 years for this hundred-fold improvement. Like past gains, significant changes in the computational methods are required for these advances. I will describe new algorithms, algorithmic hacks and a dedicated computer to perform Billion particle simulations. Finally, I will describe research that can be enabled by

An order (n) algorithm for the dynamics simulation of robotic systems

NASA Technical Reports Server (NTRS)

Chun, H. M.; Turner, J. D.; Frisch, Harold P.

1989-01-01

The formulation of an Order (n) algorithm for DISCOS (Dynamics Interaction Simulation of Controls and Structures), which is an industry-standard software package for simulation and analysis of flexible multibody systems is presented. For systems involving many bodies, the new Order (n) version of DISCOS is much faster than the current version. Results of the experimental validation of the dynamics software are also presented. The experiment is carried out on a seven-joint robot arm at NASA's Goddard Space Flight Center. The algorithm used in the current version of DISCOS requires the inverse of a matrix whose dimension is equal to the number of constraints in the system. Generally, the number of constraints in a system is roughly proportional to the number of bodies in the system, and matrix inversion requires O(p exp 3) operations, where p is the dimension of the matrix. The current version of DISCOS is therefore considered an Order (n exp 3) algorithm. In contrast, the Order (n) algorithm requires inversion of matrices which are small, and the number of matrices to be inverted increases only linearly with the number of bodies. The newly-developed Order (n) DISCOS is currently capable of handling chain and tree topologies as well as multiple closed loops. Continuing development will extend the capability of the software to deal with typical robotics applications such as put-and-place, multi-arm hand-off and surface sliding.

Benchmark results for few-body hypernuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruffino, Fabrizio Ferrari; Lonardoni, Diego; Barnea, Nir

2017-03-16

Here, the Non-Symmetrized Hyperspherical Harmonics method (NSHH) is introduced in the hypernuclear sector and benchmarked with three different ab-initio methods, namely the Auxiliary Field Diffusion Monte Carlo method, the Faddeev–Yakubovsky approach and the Gaussian Expansion Method. Binding energies and hyperon separation energies of three- to five-body hypernuclei are calculated by employing the two-body ΛN component of the phenomenological Bodmer–Usmani potential, and a hyperon-nucleon interaction simulating the scattering phase shifts given by NSC97f. The range of applicability of the NSHH method is briefly discussed.

Generalized Eigenvalues for pairs on heritian matrices

NASA Technical Reports Server (NTRS)

Rublein, George

1988-01-01

A study was made of certain special cases of a generalized eigenvalue problem. Let A and B be nxn matrics. One may construct a certain polynomial, P(A,B, lambda) which specializes to the characteristic polynomial of B when A equals I. In particular, when B is hermitian, that characteristic polynomial, P(I,B, lambda) has real roots, and one can ask: are the roots of P(A,B, lambda) real when B is hermitian. We consider the case where A is positive definite and show that when N equals 3, the roots are indeed real. The basic tools needed in the proof are Shur's theorem on majorization for eigenvalues of hermitian matrices and the interlacing theorem for the eigenvalues of a positive definite hermitian matrix and one of its principal (n-1)x(n-1) minors. The method of proof first reduces the general problem to one where the diagonal of B has a certain structure: either diag (B) = diag (1,1,1) or diag (1,1,-1), or else the 2 x 2 principal minors of B are all 1. According as B has one of these three structures, we use an appropriate method to replace A by a positive diagonal matrix. Since it can be easily verified that P(D,B, lambda) has real roots, the result follows. For other configurations of B, a scaling and a continuity argument are used to prove the result in general.

Toward a better determination of dairy powders surface composition through XPS matrices development.

PubMed

Nikolova, Y; Petit, J; Sanders, C; Gianfrancesco, A; Scher, J; Gaiani, C

2015-01-01

The surface composition of dairy powders prepared by mixing various amounts of micellar casein (MC), whey proteins isolate (WPI), lactose, and anhydrous milk fat (AMF) was investigated by XPS measurements. The use of matrices are generally accepted to transform surface atomic composition (i.e., C, O, N contents) into surface component composition (i.e., lactose, proteins, lipids). These atomic-based matrices were revisited and two new matrices based on the surface bond composition were developed. Surface compositions obtained from atomic and bond-based matrices were compared. A successful matrix allowing good correlations between XPS predicted and theoretical surface composition for powders free from fat was identified. Nevertheless, samples containing milk fat were found to present a possible segregation of components owing to the AMF overrepresentation on the surface. Supplementary analyses (FTIR, SEM) were carried out in order to investigate the homogeneity of the mixtures. Copyright © 2014 Elsevier B.V. All rights reserved.

Nonrelativistic factorizable scattering theory and the Calogero-Sutherland model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, C.; Lee, K.; Nam, S.

1996-12-01

We solve the SU({ital N})-invariant Yang-Baxter equations imposing only the unitarity condition. The usual {ital S} matrices should satisfy the crossing symmetry which originates from the {ital CPT} invariance of relativistic quantum-field theory. In this paper, we consider nonrelativistic SU({ital N})-invariant factorizable {ital S} matrices by relaxing the crossing symmetry and making the amplitudes for creating and annihilating new particles vanish and find that these {ital S} matrices are exactly the same as those of the multicomponent Calogero-Sutherland model, the quantum-mechanical model with the hyperbolic potential between particles and antiparticles. This particular solution is of interest since it cannot bemore » obtained as a nonrelativistic limit of any known relativistic solutions of the SU({ital N})-invariant Yang-Baxter equations. {copyright} {ital 1996 The American Physical Society.}« less

Scattering Cross Section of Sound Waves by the Modal Element Method

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Kreider, Kevin L.

1994-01-01

#he modal element method has been employed to determine the scattered field from a plane acoustic wave impinging on a two dimensional body. In the modal element method, the scattering body is represented by finite elements, which are coupled to an eigenfunction expansion representing the acoustic pressure in the infinite computational domain surrounding the body. The present paper extends the previous work by developing the algorithm necessary to calculate the acoustics scattering cross section by the modal element method. The scattering cross section is the acoustical equivalent to the Radar Cross Section (RCS) in electromagnetic theory. Since the scattering cross section is evaluated at infinite distance from the body, an asymptotic approximation is used in conjunction with the standard modal element method. For validation, the scattering cross section of the rigid circular cylinder is computed for the frequency range 0.1 is less than or equal to ka is less than or equal to 100. Results show excellent agreement with the analytic solution.

OBERON: OBliquity and Energy balance Run on N-body systems

NASA Astrophysics Data System (ADS)

Forgan, Duncan H.

2016-08-01

OBERON (OBliquity and Energy balance Run on N-body systems) models the climate of Earthlike planets under the effects of an arbitrary number and arrangement of other bodies, such as stars, planets and moons. The code, written in C++, simultaneously computes N body motions using a 4th order Hermite integrator, simulates climates using a 1D latitudinal energy balance model, and evolves the orbital spin of bodies using the equations of Laskar (1986a,b).

Hydration-Induced Phase Separation in Amphiphilic Polymer Matrices and its Influence on Voclosporin Release

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, I. John; Murthy, N. Sanjeeva; Kohn, Joachim

2015-10-30

Voclosporin is a highly potent, new cyclosporine -- a derivative that is currently in Phase 3 clinical trials in the USA as a potential treatment for inflammatory diseases of the eye. Voclosporin represents a number of very sparingly soluble drugs that are difficult to administer. It was selected as a model drug that is dispersed within amphiphilic polymer matrices, and investigated the changing morphology of the matrices using neutron and x-ray scattering during voclosporin release and polymer resorption. The hydrophobic segments of the amphiphilic polymer chain are comprised of desaminotyrosyl-tyrosine ethyl ester (DTE) and desaminotyrosyl-tyrosine (DT), and the hydrophilic componentmore » is poly(ethylene glycol) (PEG). Water uptake in these matrices resulted in the phase separation of hydrophobic and hydrophilic domains that are a few hundred Angstroms apart. These water-driven morphological changes influenced the release profile of voclosporin and facilitated a burst-free release from the polymer. No such morphological reorganization was observed in poly(lactide-co-glycolide) (PLGA), which exhibits an extended lag period, followed by a burst-like release of voclosporin when the polymer was degraded. An understanding of the effect of polymer composition on the hydration behavior is central to understanding and controlling the phase behavior and resorption characteristics of the matrix for achieving long-term controlled release of hydrophobic drugs such as voclosporin.« less

Condition Number Estimation of Preconditioned Matrices

PubMed Central

Kushida, Noriyuki

2015-01-01

The present paper introduces a condition number estimation method for preconditioned matrices. The newly developed method provides reasonable results, while the conventional method which is based on the Lanczos connection gives meaningless results. The Lanczos connection based method provides the condition numbers of coefficient matrices of systems of linear equations with information obtained through the preconditioned conjugate gradient method. Estimating the condition number of preconditioned matrices is sometimes important when describing the effectiveness of new preconditionerers or selecting adequate preconditioners. Operating a preconditioner on a coefficient matrix is the simplest method of estimation. However, this is not possible for large-scale computing, especially if computation is performed on distributed memory parallel computers. This is because, the preconditioned matrices become dense, even if the original matrices are sparse. Although the Lanczos connection method can be used to calculate the condition number of preconditioned matrices, it is not considered to be applicable to large-scale problems because of its weakness with respect to numerical errors. Therefore, we have developed a robust and parallelizable method based on Hager’s method. The feasibility studies are curried out for the diagonal scaling preconditioner and the SSOR preconditioner with a diagonal matrix, a tri-daigonal matrix and Pei’s matrix. As a result, the Lanczos connection method contains around 10% error in the results even with a simple problem. On the other hand, the new method contains negligible errors. In addition, the newly developed method returns reasonable solutions when the Lanczos connection method fails with Pei’s matrix, and matrices generated with the finite element method. PMID:25816331

Condition number estimation of preconditioned matrices.

PubMed

Kushida, Noriyuki

2015-01-01

The present paper introduces a condition number estimation method for preconditioned matrices. The newly developed method provides reasonable results, while the conventional method which is based on the Lanczos connection gives meaningless results. The Lanczos connection based method provides the condition numbers of coefficient matrices of systems of linear equations with information obtained through the preconditioned conjugate gradient method. Estimating the condition number of preconditioned matrices is sometimes important when describing the effectiveness of new preconditionerers or selecting adequate preconditioners. Operating a preconditioner on a coefficient matrix is the simplest method of estimation. However, this is not possible for large-scale computing, especially if computation is performed on distributed memory parallel computers. This is because, the preconditioned matrices become dense, even if the original matrices are sparse. Although the Lanczos connection method can be used to calculate the condition number of preconditioned matrices, it is not considered to be applicable to large-scale problems because of its weakness with respect to numerical errors. Therefore, we have developed a robust and parallelizable method based on Hager's method. The feasibility studies are curried out for the diagonal scaling preconditioner and the SSOR preconditioner with a diagonal matrix, a tri-daigonal matrix and Pei's matrix. As a result, the Lanczos connection method contains around 10% error in the results even with a simple problem. On the other hand, the new method contains negligible errors. In addition, the newly developed method returns reasonable solutions when the Lanczos connection method fails with Pei's matrix, and matrices generated with the finite element method.

Enhancing Understanding of Transformation Matrices

ERIC Educational Resources Information Center

Dick, Jonathan; Childrey, Maria

2012-01-01

With the Common Core State Standards' emphasis on transformations, teachers need a variety of approaches to increase student understanding. Teaching matrix transformations by focusing on row vectors gives students tools to create matrices to perform transformations. This empowerment opens many doors: Students are able to create the matrices for…

nMoldyn: a program package for a neutron scattering oriented analysis of molecular dynamics simulations.

PubMed

Róg, T; Murzyn, K; Hinsen, K; Kneller, G R

2003-04-15

We present a new implementation of the program nMoldyn, which has been developed for the computation and decomposition of neutron scattering intensities from Molecular Dynamics trajectories (Comp. Phys. Commun 1995, 91, 191-214). The new implementation extends the functionality of the original version, provides a much more convenient user interface (both graphical/interactive and batch), and can be used as a tool set for implementing new analysis modules. This was made possible by the use of a high-level language, Python, and of modern object-oriented programming techniques. The quantities that can be calculated by nMoldyn are the mean-square displacement, the velocity autocorrelation function as well as its Fourier transform (the density of states) and its memory function, the angular velocity autocorrelation function and its Fourier transform, the reorientational correlation function, and several functions specific to neutron scattering: the coherent and incoherent intermediate scattering functions with their Fourier transforms, the memory function of the coherent scattering function, and the elastic incoherent structure factor. The possibility to compute memory function is a new and powerful feature that allows to relate simulation results to theoretical studies. Copyright 2003 Wiley Periodicals, Inc. J Comput Chem 24: 657-667, 2003

Pseudo-scalar pi N coupling and relativistic proton-nucleus scattering

NASA Technical Reports Server (NTRS)

Gross, Franz; Maung, Khin Maung; Tjon, J. A.; Townsend, L. W.; Wallace, S. J.

1988-01-01

Relativistic p-Ca-40 elastic scattering observables are calculated using relativistic NN amplitudes obtained from the solution of a two-body relativistic equation in which one particle is kept on its mass-shell. Results at 200 MeV are presented for two sets of NN amplitudes, one with pure pseudo-vector coupling for the pion and another with a 25 percent admixture of pseudo-scaling coupling. Both give a very good fit to the positive energy on-shell NN data. Differences between the predictions of these two models (which are shown to be due only to the differences in their corresponding negative energy amplitudes) provide a measure of the uncertainty in contructing Dirac optical potentials from NN amplitudes.

Aspects of Strongly Correlated Many-Body Fermi Systems

NASA Astrophysics Data System (ADS)

Porter, William J., III

A, by now, well-known signal-to-noise problem plagues Monte Carlo calculations of quantum-information-theoretic observables in systems of interacting fermions, particularly the Renyi entanglement entropies Sn, even in many cases where the infamous sign problem does not appear. Several methods have been put forward to circumvent this affliction including ensemble-switching techniques using auxiliary partition-function ratios. This dissertation presents an algorithm that modifies the recently proposed free-fermion decomposition in an essential way: we incorporate the entanglement-sensitive correlations directly into the probability measure in a natural way. Implementing this algorithm, we demonstrate that it is compatible with the hybrid Monte Carlo algorithm, the workhorse of the lattice quantum chromodynamics community and an essential tool for studying gauge theories that contain dynamical fermions. By studying a simple one-dimensional Hubbard model, we demonstrate that our method does not exhibit the same debilitating numerical difficulties that naive attempts to study entanglement often encounter. Following that, we illustrate some key probabilistic insights, using intuition derived from the previous method and its successes to construct a simpler, better behaved, and more elegant algorithm. Using this method, in combination with new identities which allow us to avoid seemingly necessary numerical difficulties, the inversion of the restricted one-body density matrices, we compute high order Renyi entropies and perform a thorough comparison to this new algorithm's predecessor using the Hubbard model mentioned before. Finally, we characterize non-perturbatively the Renyi entropies of degree n = 2,3,4, and 5 of three-dimensional, strongly coupled many-fermion systems in the scale-invariant regime of short interaction range and large scattering length, i.e. in the unitary limit using the algorithms detailed herein. We also detail an exact, few-body projective method

Beyond spatial correlation effect in micro-Raman light scattering: An example of zinc-blende GaN/GaAs hetero-interface

NASA Astrophysics Data System (ADS)

Ning, J. Q.; Zheng, C. C.; Zheng, L. X.; Xu, S. J.

2015-08-01

Spatially resolved Raman light scattering experiments were performed on a zinc-blende GaN/GaAs heterostructure with confocal micro-Raman scattering technique under the backscattering geometric configuration. By varying the illumination spot locations across the heterostructure interface, we found that the Raman light scattering spectral features change remarkably. The interface effect on the GaAs substrate manifested as a much broader lineshape of the transverse optical (TO) phonon mode. Two kinds of broadening mechanisms, namely, spatial correlation induced wave-vector relaxation effect and lattice-mismatch strain + compositional intermixing effect, have been identified. The former leads to the broadening of the TO mode at the low-energy side, whereas the latter accounts for the broadening at the high-energy side. The diffuse light scattering from the highly defective nucleation layer of GaN was found to produce a broad scattering background of the GaN TO mode. The methodology and conclusions of the present work could be applicable to Raman spectroscopic studies on other material interfaces.

The underexposed role of food matrices in probiotic products: Reviewing the relationship between carrier matrices and product parameters.

PubMed

Flach, Joost; van der Waal, Mark B; van den Nieuwboer, Maurits; Claassen, Eric; Larsen, Olaf F A

2017-06-13

Probiotic microorganisms are increasingly incorporated into food matrices in order to confer proposed health benefits on the consumer. It is important that the health benefits, sensory properties, shelf-life and probiotic gastrointestinal tract (GIT) survival of these products are carefully balanced as they determine functionality and drive consumer acceptance. The strain-specific effects of probiotic species are imperative in this process but carrier matrices may play a pivotal role as well. This study therefore recapitulates the wealth of knowledge on carrier matrices and their interaction with probiotic strains. The most substantiated carrier matrices, factors that influence probiotic functionality and matrix effects on shelf-life, GIT survival and clinical efficacy are reviewed. Results indicate that carrier matrices have a significant impact on the quality of probiotic products. Matrix components, such as proteins, carbohydrates and flavoring agents are shown to alter probiotic efficacy and viability. In vivo studies furthermore revealed strain-dependent matrix effects on the GIT survival of probiotic bacteria. However, only a limited number of studies have specifically addressed the effects of carrier matrices on the aforementioned product-parameters; most studies seem to focus solely on the strain-specific effects of probiotic microorganisms. This hampers the innovation of probiotic products. More human studies, comparing not only different probiotic strains but different carrier matrices as well, are needed to drive the innovation cycle.

A Keplerian-based Hamiltonian splitting for gravitational N-body simulations

NASA Astrophysics Data System (ADS)

Gonçalves Ferrari, G.; Boekholt, T.; Portegies Zwart, S. F.

2014-05-01

We developed a Keplerian-based Hamiltonian splitting for solving the gravitational N-body problem. This splitting allows us to approximate the solution of a general N-body problem by a composition of multiple, independently evolved two-body problems. While the Hamiltonian splitting is exact, we show that the composition of independent two-body problems results in a non-symplectic non-time-symmetric first-order map. A time-symmetric second-order map is then constructed by composing this basic first-order map with its self-adjoint. The resulting method is precise for each individual two-body solution and produces quick and accurate results for near-Keplerian N-body systems, like planetary systems or a cluster of stars that orbit a supermassive black hole. The method is also suitable for integration of N-body systems with intrinsic hierarchies, like a star cluster with primordial binaries. The superposition of Kepler solutions for each pair of particles makes the method excellently suited for parallel computing; we achieve ≳64 per cent efficiency for only eight particles per core, but close to perfect scaling for 16 384 particles on a 128 core distributed-memory computer. We present several implementations in SAKURA, one of which is publicly available via the AMUSE framework.

Comparison of local exchange potentials of electron-N2 scattering

NASA Astrophysics Data System (ADS)

Rumble, J. R., Jr.; Truhlar, D. G.

1980-05-01

Vibrationally and electronically elastic electron scattering by N2 at 2-30 eV impact energy is considered. Static, static-exchange, and static-exchange-plus-polarization potentials, Cade-Sales-Wahl and INDO/1s wave functions, and semiclassical exchange and Hara free-electron-gas exchange potentials are examined. It is shown that the semiclassical exchange approximation is too attractive at low energy for N2. It is also shown quantitatively by consideration of partial and total integral cross sections how the effects of approximations to exchange become smaller as the incident energy is increased until the differences are about 8% for the total integral cross section at 30 eV.

SECULAR BEHAVIOR OF EXOPLANETS: SELF-CONSISTENCY AND COMPARISONS WITH THE PLANET-PLANET SCATTERING HYPOTHESIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timpe, Miles; Barnes, Rory; Kopparapu, Ravikumar

2013-09-15

If mutual gravitational scattering among exoplanets occurs, then it may produce unique orbital properties. For example, two-planet systems that lie near the boundary between circulation and libration of their periapses could result if planet-planet scattering ejected a former third planet quickly, leaving one planet on an eccentric orbit and the other on a circular orbit. We first improve upon previous work that examined the apsidal behavior of known multiplanet systems by doubling the sample size and including observational uncertainties. This analysis recovers previous results that demonstrated that many systems lay on the apsidal boundary between libration and circulation. We thenmore » performed over 12,000 three-dimensional N-body simulations of hypothetical three-body systems that are unstable, but stabilize to two-body systems after an ejection. Using these synthetic two-planet systems, we test the planet-planet scattering hypothesis by comparing their apsidal behavior, over a range of viewing angles, to that of the observed systems and find that they are statistically consistent regardless of the multiplicity of the observed systems. Finally, we combine our results with previous studies to show that, from the sampled cases, the most likely planetary mass function prior to planet-planet scattering follows a power law with index -1.1. We find that this pre-scattering mass function predicts a mutual inclination frequency distribution that follows an exponential function with an index between -0.06 and -0.1.« less

Relativistic initial conditions for N-body simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fidler, Christian; Tram, Thomas; Crittenden, Robert

2017-06-01

Initial conditions for (Newtonian) cosmological N-body simulations are usually set by re-scaling the present-day power spectrum obtained from linear (relativistic) Boltzmann codes to the desired initial redshift of the simulation. This back-scaling method can account for the effect of inhomogeneous residual thermal radiation at early times, which is absent in the Newtonian simulations. We analyse this procedure from a fully relativistic perspective, employing the recently-proposed Newtonian motion gauge framework. We find that N-body simulations for ΛCDM cosmology starting from back-scaled initial conditions can be self-consistently embedded in a relativistic space-time with first-order metric potentials calculated using a linear Boltzmann code.more » This space-time coincides with a simple ''N-body gauge'' for z < 50 for all observable modes. Care must be taken, however, when simulating non-standard cosmologies. As an example, we analyse the back-scaling method in a cosmology with decaying dark matter, and show that metric perturbations become large at early times in the back-scaling approach, indicating a breakdown of the perturbative description. We suggest a suitable ''forwards approach' for such cases.« less

Analysis on Vertical Scattering Signatures in Forestry with PolInSAR

NASA Astrophysics Data System (ADS)

Guo, Shenglong; Li, Yang; Zhang, Jingjing; Hong, Wen

2014-11-01

We apply accurate topographic phase to the Freeman-Durden decomposition for polarimetric SAR interferometry (PolInSAR) data. The cross correlation matrix obtained from PolInSAR observations can be decomposed into three scattering mechanisms matrices accounting for the odd-bounce, double-bounce and volume scattering. We estimate the phase based on the Random volume over Ground (RVoG) model, and as the initial input parameter of the numerical method which is used to solve the parameters of decomposition. In addition, the modified volume scattering model introduced by Y. Yamaguchi is applied to the PolInSAR target decomposition in forest areas rather than the pure random volume scattering as proposed by Freeman-Durden to make best fit to the actual measured data. This method can accurately retrieve the magnitude associated with each mechanism and their vertical location along the vertical dimension. We test the algorithms with L- and P- band simulated data.

Inference for High-dimensional Differential Correlation Matrices *

PubMed Central

Cai, T. Tony; Zhang, Anru

2015-01-01

Motivated by differential co-expression analysis in genomics, we consider in this paper estimation and testing of high-dimensional differential correlation matrices. An adaptive thresholding procedure is introduced and theoretical guarantees are given. Minimax rate of convergence is established and the proposed estimator is shown to be adaptively rate-optimal over collections of paired correlation matrices with approximately sparse differences. Simulation results show that the procedure significantly outperforms two other natural methods that are based on separate estimation of the individual correlation matrices. The procedure is also illustrated through an analysis of a breast cancer dataset, which provides evidence at the gene co-expression level that several genes, of which a subset has been previously verified, are associated with the breast cancer. Hypothesis testing on the differential correlation matrices is also considered. A test, which is particularly well suited for testing against sparse alternatives, is introduced. In addition, other related problems, including estimation of a single sparse correlation matrix, estimation of the differential covariance matrices, and estimation of the differential cross-correlation matrices, are also discussed. PMID:26500380

Inference for High-dimensional Differential Correlation Matrices.

PubMed

Cai, T Tony; Zhang, Anru

2016-01-01

Motivated by differential co-expression analysis in genomics, we consider in this paper estimation and testing of high-dimensional differential correlation matrices. An adaptive thresholding procedure is introduced and theoretical guarantees are given. Minimax rate of convergence is established and the proposed estimator is shown to be adaptively rate-optimal over collections of paired correlation matrices with approximately sparse differences. Simulation results show that the procedure significantly outperforms two other natural methods that are based on separate estimation of the individual correlation matrices. The procedure is also illustrated through an analysis of a breast cancer dataset, which provides evidence at the gene co-expression level that several genes, of which a subset has been previously verified, are associated with the breast cancer. Hypothesis testing on the differential correlation matrices is also considered. A test, which is particularly well suited for testing against sparse alternatives, is introduced. In addition, other related problems, including estimation of a single sparse correlation matrix, estimation of the differential covariance matrices, and estimation of the differential cross-correlation matrices, are also discussed.

Precision determination of the πN scattering lengths and the charged πNN coupling constant

NASA Astrophysics Data System (ADS)

Ericson, T. E. O.; Loiseau, B.; Thomas, A. W.

2000-01-01

We critically evaluate the isovector GMO sumrule for the charged πNN coupling constant using recent precision data from π-p and π-d atoms and with careful attention to systematic errors. From the π-d scattering length we deduce the pion-proton scattering lengths 1/2(aπ-p + aπ-n) = (-20 +/- 6(statistic)+/-10 (systematic) .10-4m-1πc and 1/2(aπ-p - aπ-n) = (903 +/- 14) . 10-4m-1πc. From this a direct evaluation gives g2c(GMO)/4π = 14.20 +/- 0.07 (statistic)+/-0.13(systematic) or f2c/4π = 0.0786 +/- 0.0008.

Computer-Access-Code Matrices

NASA Technical Reports Server (NTRS)

Collins, Earl R., Jr.

1990-01-01

Authorized users respond to changing challenges with changing passwords. Scheme for controlling access to computers defeats eavesdroppers and "hackers". Based on password system of challenge and password or sign, challenge, and countersign correlated with random alphanumeric codes in matrices of two or more dimensions. Codes stored on floppy disk or plug-in card and changed frequently. For even higher security, matrices of four or more dimensions used, just as cubes compounded into hypercubes in concurrent processing.

Quantum mechanical prediction of four-phonon scattering rates and reduced thermal conductivity of solids

NASA Astrophysics Data System (ADS)

Feng, Tianli; Ruan, Xiulin

2016-01-01

Recently, first principle-based predictions of lattice thermal conductivity κ from perturbation theory have achieved significant success. However, it only includes three-phonon scattering due to the assumption that four-phonon and higher-order processes are generally unimportant. Also, directly evaluating the scattering rates of four-phonon and higher-order processes has been a long-standing challenge. In this work, however, we have developed a formalism to explicitly determine quantum mechanical scattering probability matrices for four-phonon scattering in the full Brillouin zone, and by mitigating the computational challenge we have directly calculated four-phonon scattering rates. We find that four-phonon scattering rates are comparable to three-phonon scattering rates at medium and high temperatures, and they increase quadratically with temperature. As a consequence, κ of Lennard-Jones argon is reduced by more than 60% at 80 K when four-phonon scattering is included. Also, in less anharmonic materials—diamond, silicon, and germanium—κ is still reduced considerably at high temperature by four-phonon scattering by using the classical Tersoff potentials. Also, the thermal conductivity of optical phonons is dominated by the fourth- and higher-orders phonon scattering even at low temperature.

Effect of body size and body mass on δ 13 C and δ 15 N in coastal fishes and cephalopods

NASA Astrophysics Data System (ADS)

Vinagre, C.; Máguas, C.; Cabral, H. N.; Costa, M. J.

2011-11-01

Carbon and nitrogen isotopes have been widely used in the investigation of trophic relations, energy pathways, trophic levels and migrations, under the assumption that δ 13C is independent of body size and that variation in δ 15N occurs exclusively due to ontogenetic changes in diet and not body size increase per se. However, several studies have shown that these assumptions are uncertain. Data from food-webs containing an important number of species lack theoretical support on these assumptions because very few species have been tested for δ 13C and δ 15N variation in captivity. However, if sampling comprises a wide range of body sizes from various species, the variation of δ 13C and δ 15N with body size can be investigated. While correlation between body size and δ 13C and δ 15N can be due to ontogenetic diet shifts, stability in such values throughout the size spectrum can be considered an indication that δ 13C and δ 15N in muscle tissues of such species is independent of body size within that size range, and thus the basic assumptions can be applied in the interpretation of such food webs. The present study investigated the variation in muscle δ 13C and δ 15N with body size and body mass of coastal fishes and cephalopods. It was concluded that muscle δ 13C and δ 15N did not vary with body size or mass for all bony fishes with only one exception, the dragonet Callionymus lyra. Muscle δ 13C and δ 15N also did not vary with body size or mass in cartilaginous fishes and cephalopods, meaning that body size/mass per se have no effect on δ 13C or δ 15N, for most species analysed and within the size ranges sampled. The assumption that δ 13C is independent of body size and that variation in δ 15N is not affected by body size increase per se was upheld for most organisms and can be applied to the coastal food web studied taking into account that C. lyra is an exception.

A scattering model for forested area

NASA Technical Reports Server (NTRS)

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

1988-01-01

A forested area is modeled as a volume of randomly oriented and distributed disc-shaped, or needle-shaped leaves shading a distribution of branches modeled as randomly oriented finite-length, dielectric cylinders above an irregular soil surface. Since the radii of branches have a wide range of sizes, the model only requires the length of a branch to be large compared with its radius which may be any size relative to the incident wavelength. In addition, the model also assumes the thickness of a disc-shaped leaf or the radius of a needle-shaped leaf is much smaller than the electromagnetic wavelength. The scattering phase matrices for disc, needle, and cylinder are developed in terms of the scattering amplitudes of the corresponding fields which are computed by the forward scattering theorem. These quantities along with the Kirchoff scattering model for a randomly rough surface are used in the standard radiative transfer formulation to compute the backscattering coefficient. Numerical illustrations for the backscattering coefficient are given as a function of the shading factor, incidence angle, leaf orientation distribution, branch orientation distribution, and the number density of leaves. Also illustrated are the properties of the extinction coefficient as a function of leaf and branch orientation distributions. Comparisons are made with measured backscattering coefficients from forested areas reported in the literature.

Two-Center Evaluation of Disinfectant Efficacy against Ebola Virus in Clinical and Laboratory Matrices.

PubMed

Smither, Sophie J; Eastaugh, Lin; Filone, Claire Marie; Freeburger, Denise; Herzog, Artemas; Lever, M Stephen; Miller, David M; Mitzel, Dana; Noah, James W; Reddick-Elick, Mary S; Reese, Amy; Schuit, Michael; Wlazlowski, Carly B; Hevey, Michael; Wahl-Jensen, Victoria

2018-01-01

Ebola virus (EBOV) in body fluids poses risk for virus transmission. However, there are limited experimental data for such matrices on the disinfectant efficacy against EBOV. We evaluated the effectiveness of disinfectants against EBOV in blood on surfaces. Only 5% peracetic acid consistently reduced EBOV titers in dried blood to the assay limit of quantification.

REBOUND-ing Off Asteroids: An N-body Particle Model for Ejecta Dynamics on Small Bodies

NASA Astrophysics Data System (ADS)

Larson, Jennifer; Sarid, Gal

2017-10-01

Here we describe our numerical approach to model the evolution of ejecta clouds. Modeling with an N-body particle method enables us to study the micro-dynamics while varying the particle size distribution. A hydrodynamic approach loses many of the fine particle-particle interactions included in the N-body particle approach (Artemieva 2008).We use REBOUND, an N-body integration package (Rein et al. 2012) developed to model various dynamical systems (planetary orbits, ring systems, etc.) with high resolution calculations at a lower performance cost than other N-body integrators (Rein & Tamayo 2017). It offers both symplectic (WHFast) and non-symplectic (IAS15) methods (Rein & Spiegel 2014, Rein & Tamayo 2015). We primarily use the IAS15 integrator due to its robustness and accuracy with short interaction distances and non-conservative forces. We implemented a wrapper (developed in Python) to handle changes in time step and integrator at different stages of ejecta particle evolution.To set up the system, each particle is given a velocity away from the target body’s surface at a given angle within a defined ejecta cone. We study the ejecta cloud evolution beginning immediately after an impact rather than the actual impact itself. This model considers effects such as varying particle size distribution, radiation pressure, perturbations from a binary component, particle-particle collisions and non-axisymmetric gravity of the target body. Restrictions on the boundaries of the target body’s surface define the physical shape and help count the number of particles that land on the target body. Later, we will build the central body from individual particles to allow for a wider variety of target body shapes and topographies.With our particle modeling approach, individual particle trajectories are tracked and predicted on short, medium and long timescales. Our approach will be applied to modeling of the ejecta cloud produced during the Double Asteroid Redirection Test

Electromagnetic scattering from a class of open-ended waveguide discontinuities

NASA Technical Reports Server (NTRS)

Altintas, A.; Pathak, P. H.; Burnside, Walter D.

1986-01-01

A relatively simple high frequency analysis of electromagnetic scattering from a class of open-ended waveguide discontinuites was developed. The waveguides are composed of perfectly-conducting sections in which the electromagnetic field can be written as the sum of waveguide modes. Junctions are formed at the open end and also within interior regions where different sections are joined. The reflection and transmission properties of each junction are described in terms of a scattering matrix which is determined by combining the modal ray picture with high frequency techniques such as the Geometrical Theory of Diffraction (GTD), the Equivalent Current Method (ECM), and modifications of the Physical Theory of Diffraction (PTD). A new set of equivalent circuits are employed in this ECM analysis which leads to a simple treatment of many types of junction discontinuities. Also, a new procedure is presented to improve the efficiency of the aperture integration at the open end which is required in the PTD procedure for finding the fields radiated from (or coupled to) the open end. Once the scattering matrices are determined, they are then combined using a self-consistent multiple scattering method to obtain the total scattered fields.

An N-body Integrator for Planetary Rings

NASA Astrophysics Data System (ADS)

Hahn, Joseph M.

2011-04-01

A planetary ring that is disturbed by a satellite's resonant perturbation can respond in an organized way. When the resonance lies in the ring's interior, the ring responds via an m-armed spiral wave, while a ring whose edge is confined by the resonance exhibits an m-lobed scalloping along the ring-edge. The amplitude of these disturbances are sensitive to ring surface density and viscosity, so modelling these phenomena can provide estimates of the ring's properties. However a brute force attempt to simulate a ring's full azimuthal extent with an N-body code will likely fail because of the large number of particles needed to resolve the ring's behavior. Another impediment is the gravitational stirring that occurs among the simulated particles, which can wash out the ring's organized response. However it is possible to adapt an N-body integrator so that it can simulate a ring's collective response to resonant perturbations. The code developed here uses a few thousand massless particles to trace streamlines within the ring. Particles are close in a radial sense to these streamlines, which allows streamlines to be treated as straight wires of constant linear density. Consequently, gravity due to these streamline is a simple function of the particle's radial distance to all streamlines. And because particles are responding to smooth gravitating streamlines, rather than discrete particles, this method eliminates the stirring that ordinarily occurs in brute force N-body calculations. Note also that ring surface density is now a simple function of streamline separations, so effects due to ring pressure and viscosity are easily accounted for, too. A poster will describe this N-body method in greater detail. Simulations of spiral density waves and scalloped ring-edges are executed in typically ten minutes on a desktop PC, and results for Saturn's A and B rings will be presented at conference time.

ZENO: N-body and SPH Simulation Codes

NASA Astrophysics Data System (ADS)

Barnes, Joshua E.

2011-02-01

The ZENO software package integrates N-body and SPH simulation codes with a large array of programs to generate initial conditions and analyze numerical simulations. Written in C, the ZENO system is portable between Mac, Linux, and Unix platforms. It is in active use at the Institute for Astronomy (IfA), at NRAO, and possibly elsewhere. Zeno programs can perform a wide range of simulation and analysis tasks. While many of these programs were first created for specific projects, they embody algorithms of general applicability and embrace a modular design strategy, so existing code is easily applied to new tasks. Major elements of the system include: Structured data file utilities facilitate basic operations on binary data, including import/export of ZENO data to other systems.Snapshot generation routines create particle distributions with various properties. Systems with user-specified density profiles can be realized in collisionless or gaseous form; multiple spherical and disk components may be set up in mutual equilibrium.Snapshot manipulation routines permit the user to sift, sort, and combine particle arrays, translate and rotate particle configurations, and assign new values to data fields associated with each particle.Simulation codes include both pure N-body and combined N-body/SPH programs: Pure N-body codes are available in both uniprocessor and parallel versions.SPH codes offer a wide range of options for gas physics, including isothermal, adiabatic, and radiating models. Snapshot analysis programs calculate temporal averages, evaluate particle statistics, measure shapes and density profiles, compute kinematic properties, and identify and track objects in particle distributions.Visualization programs generate interactive displays and produce still images and videos of particle distributions; the user may specify arbitrary color schemes and viewing transformations.

Two-Center Evaluation of Disinfectant Efficacy against Ebola Virus in Clinical and Laboratory Matrices

PubMed Central

Smither, Sophie J.; Eastaugh, Lin; Filone, Claire Marie; Freeburger, Denise; Herzog, Artemas; Lever, M. Stephen; Miller, David M.; Mitzel, Dana; Noah, James W.; Reddick-Elick, Mary S.; Reese, Amy; Schuit, Michael; Wlazlowski, Carly B.; Hevey, Michael

2018-01-01

Ebola virus (EBOV) in body fluids poses risk for virus transmission. However, there are limited experimental data for such matrices on the disinfectant efficacy against EBOV. We evaluated the effectiveness of disinfectants against EBOV in blood on surfaces. Only 5% peracetic acid consistently reduced EBOV titers in dried blood to the assay limit of quantification. PMID:29261093

Scattering transform for nonstationary Schroedinger equation with bidimensionally perturbed N-soliton potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boiti, M.; Pempinelli, F.; Pogrebkov, A. K.

2006-12-15

In the framework of the extended resolvent approach the direct and inverse scattering problems for the nonstationary Schroedinger equation with a potential being a perturbation of the N-soliton potential by means of a generic bidimensional smooth function decaying at large spaces are introduced and investigated. The initial value problem of the Kadomtsev-Petviashvili I equation for a solution describing N wave solitons on a generic smooth decaying background is then linearized, giving the time evolution of the spectral data.

Back scattering involving embedded silicon nitride (SiN) nanoparticles for c-Si solar cells

NASA Astrophysics Data System (ADS)

Ghosh, Hemanta; Mitra, Suchismita; Siddiqui, M. S.; Saxena, A. K.; Chaudhuri, Partha; Saha, Hiranmay; Banerjee, Chandan

2018-04-01

A novel material, structure and method of synthesis for dielectric light trapping have been presented in this paper. First, the light scattering behaviour of silicon nitride nanoparticles have been theoretically studied in order to find the optimized size for dielectric back scattering by FDTD simulations from Lumerical Inc. The optical results have been used in electrical analysis and thereby, estimate the effect of nanoparticles on efficiency of the solar cells depending on substrate thickness. Experimentally, silicon nitride (SiN) nanoparticles have been formed using hydrogen plasma treatment on SiN layer deposited by Plasma Enhanced Chemical Vapour Deposition (PECVD). The size and area coverage of the nanoparticles were controlled by varying the working pressure, power density and treatment duration. The nanoparticles were integrated with partial rear contact c-Si solar cells as dielectric back reflector structures for the light trapping in thin silicon solar cells. Experimental results revealed the increases of current density by 2.7% in presence of SiN nanoparticles.

Multiple Scattering in Planetary Regoliths Using Incoherent Interactions

NASA Astrophysics Data System (ADS)

Muinonen, K.; Markkanen, J.; Vaisanen, T.; Penttilä, A.

2017-12-01

We consider scattering of light by a planetary regolith using novel numerical methods for discrete random media of particles. Understanding the scattering process is of key importance for spectroscopic, photometric, and polarimetric modeling of airless planetary objects, including radar studies. In our modeling, the size of the spherical random medium can range from microscopic to macroscopic sizes, whereas the particles are assumed to be of the order of the wavelength in size. We extend the radiative transfer and coherent backscattering method (RT-CB) to the case of dense packing of particles by adopting the ensemble-averaged first-order incoherent extinction, scattering, and absorption characteristics of a volume element of particles as input. In the radiative transfer part, at each absorption and scattering process, we account for absorption with the help of the single-scattering albedo and peel off the Stokes parameters of radiation emerging from the medium in predefined scattering angles. We then generate a new scattering direction using the joint probability density for the local polar and azimuthal scattering angles. In the coherent backscattering part, we utilize amplitude scattering matrices along the radiative-transfer path and the reciprocal path. Furthermore, we replace the far-field interactions of the RT-CB method with rigorous interactions facilitated by the Superposition T-matrix method (STMM). This gives rise to a new RT-RT method, radiative transfer with reciprocal interactions. For microscopic random media, we then compare the new results to asymptotically exact results computed using the STMM, succeeding in the numerical validation of the new methods.Acknowledgments. Research supported by European Research Council with Advanced Grant No. 320773 SAEMPL, Scattering and Absorption of ElectroMagnetic waves in ParticuLate media. Computational resources provided by CSC - IT Centre for Science Ltd, Finland.

Electromagnetic scattering of large structures in layered earths using integral equations

NASA Astrophysics Data System (ADS)

Xiong, Zonghou; Tripp, Alan C.

1995-07-01

An electromagnetic scattering algorithm for large conductivity structures in stratified media has been developed and is based on the method of system iteration and spatial symmetry reduction using volume electric integral equations. The method of system iteration divides a structure into many substructures and solves the resulting matrix equation using a block iterative method. The block submatrices usually need to be stored on disk in order to save computer core memory. However, this requires a large disk for large structures. If the body is discretized into equal-size cells it is possible to use the spatial symmetry relations of the Green's functions to regenerate the scattering impedance matrix in each iteration, thus avoiding expensive disk storage. Numerical tests show that the system iteration converges much faster than the conventional point-wise Gauss-Seidel iterative method. The numbers of cells do not significantly affect the rate of convergency. Thus the algorithm effectively reduces the solution of the scattering problem to an order of O(N2), instead of O(N3) as with direct solvers.

Novel ionic liquid matrices for qualitative and quantitative detection of carbohydrates by matrix assisted laser desorption/ionization mass spectrometry.

PubMed

Zhao, Xiaoyong; Shen, Shanshan; Wu, Datong; Cai, Pengfei; Pan, Yuanjiang

2017-09-08

Analysis of carbohydrates based on matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is still challenging and researchers have been devoting themselves to efficient matrices discovery. In the present study, the design, synthesis, qualitative and quantitative performance of non-derivative ionic liquid matrices (ILMs) were reported. DHB/N-methylaniline (N-MA) and DHB/N-ethylaniline (N-EA), performing best for carbohydrate detection, have been screened out. The limit of detection for oligosaccharide provided by DHB/N-MA and DHB/N-EA were as low as 10 fmol. DHB/N-MA and DHB/N-EA showed significantly higher ion generation efficiency than DHB. The comparison of capacity to probe polysaccharide between these two ILMs and DHB also revealed their powerful potential. Their outstanding performance were probably due to lower proton affinities and stronger UV absorption at λ = 355 nm. What is more, taking DHB/N-MA as an example, quantitative analysis of fructo-oligosaccharide mixtures extracted and identified from rice noodles has been accomplished sensitively using an internal standard method. Overall, DHB/N-MA and DHB/N-EA exhibited excellent performance and might be significant sources as the carbohydrate matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

Three-dimensional neural differentiation of embryonic stem cells with ACM induction in microfibrous matrices in bioreactors.

PubMed

Liu, Ning; Ouyang, Anli; Li, Yan; Yang, Shang-Tian

2013-01-01

The clinical use of pluripotent stem cell (PSC)-derived neural cells requires an efficient differentiation process for mass production in a bioreactor. Toward this goal, neural differentiation of murine embryonic stem cells (ESCs) in three-dimensional (3D) polyethylene terephthalate microfibrous matrices was investigated in this study. To streamline the process and provide a platform for process integration, the neural differentiation of ESCs was induced with astrocyte-conditioned medium without the formation of embryoid bodies, starting from undifferentiated ESC aggregates expanded in a suspension bioreactor. The 3D neural differentiation was able to generate a complex neural network in the matrices. When compared to 2D differentiation, 3D differentiation in microfibrous matrices resulted in a higher percentage of nestin-positive cells (68% vs. 54%) and upregulated gene expressions of nestin, Nurr1, and tyrosine hydroxylase. High purity of neural differentiation in 3D microfibrous matrix was also demonstrated in a spinner bioreactor with 74% nestin + cells. This study demonstrated the feasibility of a scalable process based on 3D differentiation in microfibrous matrices for the production of ESC-derived neural cells. © 2013 American Institute of Chemical Engineers.

Simulation and analysis of light scattering by multilamellar bodies present in the human eye

PubMed Central

Méndez-Aguilar, Emilia M.; Kelly-Pérez, Ismael; Berriel-Valdos, L. R.; Delgado-Atencio, José A.

2017-01-01

A modified computational model of the human eye was used to obtain and compare different probability density functions, radial profiles of light pattern distributions, and images of the point spread function formed in the human retina under the presence of different kinds of particles inside crystalline lenses suffering from cataracts. Specifically, this work uses simple particles without shells and multilamellar bodies (MLBs) with shells. The emergence of such particles alters the formation of images on the retina. Moreover, the MLBs change over time, which affects properties such as the refractive index of their shell. Hence, this work not only simulates the presence of such particles but also evaluates the incidence of particle parameters such as particle diameter, particle thickness, and shell refractive index, which are set based on reported experimental values. In addition, two wavelengths (400 nm and 700 nm) are used for light passing through the different layers of the computational model. The effects of these parameters on light scattering are analyzed using the simulation results. Further, in these results, the effects of light scattering on image formation can be seen when single particles, early-stage MLBs, or mature MLBs are incorporated in the model. Finally, it is found that particle diameter has the greatest impact on image formation. PMID:28663924

Simulation and analysis of light scattering by multilamellar bodies present in the human eye.

PubMed

Méndez-Aguilar, Emilia M; Kelly-Pérez, Ismael; Berriel-Valdos, L R; Delgado-Atencio, José A

2017-06-01

A modified computational model of the human eye was used to obtain and compare different probability density functions, radial profiles of light pattern distributions, and images of the point spread function formed in the human retina under the presence of different kinds of particles inside crystalline lenses suffering from cataracts. Specifically, this work uses simple particles without shells and multilamellar bodies (MLBs) with shells. The emergence of such particles alters the formation of images on the retina. Moreover, the MLBs change over time, which affects properties such as the refractive index of their shell. Hence, this work not only simulates the presence of such particles but also evaluates the incidence of particle parameters such as particle diameter, particle thickness, and shell refractive index, which are set based on reported experimental values. In addition, two wavelengths (400 nm and 700 nm) are used for light passing through the different layers of the computational model. The effects of these parameters on light scattering are analyzed using the simulation results. Further, in these results, the effects of light scattering on image formation can be seen when single particles, early-stage MLBs, or mature MLBs are incorporated in the model. Finally, it is found that particle diameter has the greatest impact on image formation.

Conduction band fluctuation scattering due to alloy clustering in barrier layers in InAlN/GaN heterostructures

NASA Astrophysics Data System (ADS)

Li, Qun; Chen, Qian; Chong, Jing

2017-12-01

In InAlN/GaN heterostructures, alloy clustering-induced InAlN conduction band fluctuations interact with electrons penetrating into the barrier layers and thus affect the electron transport. Based on the statistical description of InAlN compositional distribution, a theoretical model of the conduction band fluctuation scattering (CBFS) is presented. The model calculations show that the CBFS-limited mobility decreases with increasing two-dimensional electron gas sheet density and is inversely proportional to the squared standard deviation of In distribution. The AlN interfacial layer can effectively suppress the CBFS via decreasing the penetration probability. This model is directed towards understanding the transport properties in heterostructure materials with columnar clusters.

A Brief Historical Introduction to Matrices and Their Applications

ERIC Educational Resources Information Center

Debnath, L.

2014-01-01

This paper deals with the ancient origin of matrices, and the system of linear equations. Included are algebraic properties of matrices, determinants, linear transformations, and Cramer's Rule for solving the system of algebraic equations. Special attention is given to some special matrices, including matrices in graph theory and electrical…

Medical imaging feasibility in body fluids using Markov chains

NASA Astrophysics Data System (ADS)

Kavehrad, M.; Armstrong, A. D.

2017-02-01

A relatively wide field-of-view and high resolution imaging is necessary for navigating the scope within the body, inspecting tissue, diagnosing disease, and guiding surgical interventions. As the large number of modes available in the multimode fibers (MMF) provides higher resolution, MMFs could replace the millimeters-thick bundles of fibers and lenses currently used in endoscopes. However, attributes of body fluids and obscurants such as blood, impose perennial limitations on resolution and reliability of optical imaging inside human body. To design and evaluate optimum imaging techniques that operate under realistic body fluids conditions, a good understanding of the channel (medium) behavior is necessary. In most prior works, Monte-Carlo Ray Tracing (MCRT) algorithm has been used to analyze the channel behavior. This task is quite numerically intensive. The focus of this paper is on investigating the possibility of simplifying this task by a direct extraction of state transition matrices associated with standard Markov modeling from the MCRT computer simulations programs. We show that by tracing a photon's trajectory in the body fluids via a Markov chain model, the angular distribution can be calculated by simple matrix multiplications. We also demonstrate that the new approach produces result that are close to those obtained by MCRT and other known methods. Furthermore, considering the fact that angular, spatial, and temporal distributions of energy are inter-related, mixing time of Monte- Carlo Markov Chain (MCMC) for different types of liquid concentrations is calculated based on Eigen-analysis of the state transition matrix and possibility of imaging in scattering media are investigated. To this end, we have started to characterize the body fluids that reduce the resolution of imaging [1].

Arrowheaded enhanced multivariance products representation for matrices (AEMPRM): Specifically focusing on infinite matrices and converting arrowheadedness to tridiagonality

NASA Astrophysics Data System (ADS)

Özdemir, Gizem; Demiralp, Metin

2015-12-01

In this work, Enhanced Multivariance Products Representation (EMPR) approach which is a Demiralp-and-his- group extension to the Sobol's High Dimensional Model Representation (HDMR) has been used as the basic tool. Their discrete form have also been developed and used in practice by Demiralp and his group in addition to some other authors for the decomposition of the arrays like vectors, matrices, or multiway arrays. This work specifically focuses on the decomposition of infinite matrices involving denumerable infinitely many rows and columns. To this end the target matrix is first decomposed to the sum of certain outer products and then each outer product is treated by Tridiagonal Matrix Enhanced Multivariance Products Representation (TMEMPR) which has been developed by Demiralp and his group. The result is a three-matrix- factor-product whose kernel (the middle factor) is an arrowheaded matrix while the pre and post factors are invertable matrices decomposed of the support vectors of TMEMPR. This new method is called as Arrowheaded Enhanced Multivariance Products Representation for Matrices. The general purpose is approximation of denumerably infinite matrices with the new method.

Systematic analysis of inelastic α scattering off self-conjugate A =4 n nuclei

NASA Astrophysics Data System (ADS)

Adachi, S.; Kawabata, T.; Minomo, K.; Kadoya, T.; Yokota, N.; Akimune, H.; Baba, T.; Fujimura, H.; Fujiwara, M.; Funaki, Y.; Furuno, T.; Hashimoto, T.; Hatanaka, K.; Inaba, K.; Ishii, Y.; Itoh, M.; Iwamoto, C.; Kawase, K.; Maeda, Y.; Matsubara, H.; Matsuda, Y.; Matsuno, H.; Morimoto, T.; Morita, H.; Murata, M.; Nanamura, T.; Ou, I.; Sakaguchi, S.; Sasamoto, Y.; Sawada, R.; Shimizu, Y.; Suda, K.; Tamii, A.; Tameshige, Y.; Tsumura, M.; Uchida, M.; Uesaka, T.; Yoshida, H. P.; Yoshida, S.

2018-01-01

We systematically measured the differential cross sections of inelastic α scattering off self-conjugate A =4 n nuclei at two incident energies Eα=130 MeV and 386 MeV at Research Center for Nuclear Physics, Osaka University. The measured cross sections were analyzed by the distorted-wave Born-approximation (DWBA) calculation using the single-folding potentials, which are obtained by folding macroscopic transition densities with the phenomenological α N interaction. The DWBA calculation with the density-dependent α N interaction systematically overestimates the cross sections for the Δ L =0 transitions. However, the DWBA calculation using the density-independent α N interaction reasonably well describes all the transitions with Δ L =0 -4. We examined uncertainties in the present DWBA calculation stemming from the macroscopic transition densities, distorting potentials, phenomenological α N interaction, and coupled channel effects in 12C. It was found that the DWBA calculation is not sensitive to details of the transition densities nor the distorting potentials, and the phenomenological density-independent α N interaction gives reasonable results. The coupled-channel effects are negligibly small for the 21+ and 31- states in 12C, but not for the 02+ state. However, the DWBA calculation using the density-independent interaction at Eα=386 MeV is still reasonable even for the 02+ state. We concluded that the macroscopic DWBA calculations using the density-independent interaction are reliably applicable to the analysis of inelastic α scattering at Eα˜100 MeV /u .

Stability of the Euler resting N-body relative equilibria

NASA Astrophysics Data System (ADS)

Scheeres, D. J.

2018-03-01

The stability of a system of N equal-sized mutually gravitating spheres resting on each other in a straight line and rotating in inertial space is considered. This is a generalization of the "Euler Resting" configurations previously analyzed in the finite density 3 and 4 body problems. Specific questions for the general case are how rapidly the system must spin for the configuration to stabilize, how rapidly it can spin before the components separate from each other, and how these results change as a function of N. This paper shows that the Euler Resting configuration can only be stable for up to 5 bodies and that for 6 or more bodies the configuration can never be stable. This places an ideal limit of 5:1 on the aspect ratio of a rubble pile body's shape.

ESTIMATION OF FUNCTIONALS OF SPARSE COVARIANCE MATRICES.

PubMed

Fan, Jianqing; Rigollet, Philippe; Wang, Weichen

High-dimensional statistical tests often ignore correlations to gain simplicity and stability leading to null distributions that depend on functionals of correlation matrices such as their Frobenius norm and other ℓ r norms. Motivated by the computation of critical values of such tests, we investigate the difficulty of estimation the functionals of sparse correlation matrices. Specifically, we show that simple plug-in procedures based on thresholded estimators of correlation matrices are sparsity-adaptive and minimax optimal over a large class of correlation matrices. Akin to previous results on functional estimation, the minimax rates exhibit an elbow phenomenon. Our results are further illustrated in simulated data as well as an empirical study of data arising in financial econometrics.

ESTIMATION OF FUNCTIONALS OF SPARSE COVARIANCE MATRICES

PubMed Central

Fan, Jianqing; Rigollet, Philippe; Wang, Weichen

2016-01-01

High-dimensional statistical tests often ignore correlations to gain simplicity and stability leading to null distributions that depend on functionals of correlation matrices such as their Frobenius norm and other ℓr norms. Motivated by the computation of critical values of such tests, we investigate the difficulty of estimation the functionals of sparse correlation matrices. Specifically, we show that simple plug-in procedures based on thresholded estimators of correlation matrices are sparsity-adaptive and minimax optimal over a large class of correlation matrices. Akin to previous results on functional estimation, the minimax rates exhibit an elbow phenomenon. Our results are further illustrated in simulated data as well as an empirical study of data arising in financial econometrics. PMID:26806986

Cluster Adjacency Properties of Scattering Amplitudes in N =4 Supersymmetric Yang-Mills Theory

NASA Astrophysics Data System (ADS)

Drummond, James; Foster, Jack; Gürdoǧan, Ömer

2018-04-01

We conjecture a new set of analytic relations for scattering amplitudes in planar N =4 super Yang-Mills theory. They generalize the Steinmann relations and are expressed in terms of the cluster algebras associated to Gr (4 ,n ). In terms of the symbol, they dictate which letters can appear consecutively. We study heptagon amplitudes and integrals in detail and present symbols for previously unknown integrals at two and three loops which support our conjecture.

Direct rapid analysis of trace bioavailable soil macronutrients by chemometrics-assisted energy dispersive X-ray fluorescence and scattering spectrometry.

PubMed

Kaniu, M I; Angeyo, K H; Mwala, A K; Mangala, M J

2012-06-04

Precision agriculture depends on the knowledge and management of soil quality (SQ), which calls for affordable, simple and rapid but accurate analysis of bioavailable soil nutrients. Conventional SQ analysis methods are tedious and expensive. We demonstrate the utility of a new chemometrics-assisted energy dispersive X-ray fluorescence and scattering (EDXRFS) spectroscopy method we have developed for direct rapid analysis of trace 'bioavailable' macronutrients (i.e. C, N, Na, Mg, P) in soils. The method exploits, in addition to X-ray fluorescence, the scatter peaks detected from soil pellets to develop a model for SQ analysis. Spectra were acquired from soil samples held in a Teflon holder analyzed using (109)Cd isotope source EDXRF spectrometer for 200 s. Chemometric techniques namely principal component analysis (PCA), partial least squares (PLS) and artificial neural networks (ANNs) were utilized for pattern recognition based on fluorescence and Compton scatter peaks regions, and to develop multivariate quantitative calibration models based on Compton scatter peak respectively. SQ analyses were realized with high CMD (R(2)>0.9) and low SEP (0.01% for N and Na, 0.05% for C, 0.08% for Mg and 1.98 μg g(-1) for P). Comparison of predicted macronutrients with reference standards using a one-way ANOVA test showed no statistical difference at 95% confidence level. To the best of the authors' knowledge, this is the first time that an XRF method has demonstrated utility in trace analysis of macronutrients in soil or related matrices. Copyright © 2012 Elsevier B.V. All rights reserved.

A simple quantum mechanical treatment of scattering in nanoscale transistors

NASA Astrophysics Data System (ADS)

Venugopal, R.; Paulsson, M.; Goasguen, S.; Datta, S.; Lundstrom, M. S.

2003-05-01

We present a computationally efficient, two-dimensional quantum mechanical simulation scheme for modeling dissipative electron transport in thin body, fully depleted, n-channel, silicon-on-insulator transistors. The simulation scheme, which solves the nonequilibrium Green's function equations self consistently with Poisson's equation, treats the effect of scattering using a simple approximation inspired by the "Büttiker probes," often used in mesoscopic physics. It is based on an expansion of the active device Hamiltonian in decoupled mode space. Simulation results are used to highlight quantum effects, discuss the physics of scattering and to relate the quantum mechanical quantities used in our model to experimentally measured low field mobilities. Additionally, quantum boundary conditions are rigorously derived and the effects of strong off-equilibrium transport are examined. This paper shows that our approximate treatment of scattering, is an efficient and useful simulation method for modeling electron transport in nanoscale, silicon-on-insulator transistors.

Update on the direct n-n scattering experiment at the reactor YAGUAR

NASA Astrophysics Data System (ADS)

Stephenson, S. L.; Crawford, B. E.; Furman, W. I.; Lychagin, E. V.; Muzichka, A. Yu.; Nekhaev, G. V.; Sharapov, E. I.; Shvetsov, V. N.; Strelkov, A. V.; Levakov, B. G.; Lyzhin, A. E.; Chernukhin, Yu. I.; Howell, C. R.; Mitchell, G. E.; Tornow, W.; Showalter-Bucher, R. A.

2013-10-01

The first direct measurement of the 1S0 neutron-neutron scattering experiment using the YAGUAR aperiodic reactor at the Russian Federal Nuclear Center - All Russian Research Institute of Technical Physics has preliminary results. Thermal neutrons are scattered from a thermal neutron ``gas'' within the scattering chamber of the reactor and measured via time-of-flight. These initial results show an unexpectedly large thermal neutron background now understood to be from radiation-induced desorption within the scattering chamber. Analysis of the neutron time-of-flight spectra suggests neutron scattering from H2 and possibly H2O molecules. An experimental value for the desorption yield ηγ of 0.02 molecules/gamma agrees with modeled results. Techniques to reduce the effect of the nonthermal desorption will be presented. This work was supported in part by ISTC project No. 2286, Russia Found. Grant 01-02-17181, the US DOE grants Nos. DE-FG02-97-ER41042 and DE-FG02-97-ER41033, and by the US NSF through Award Nos. 0107263 and 0555652.

Anisotropic scattering effect of the inclined misfit dislocation on the two-dimensional electron gas in Al(In)GaN/GaN heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Dong-Dong; Department of Physics, Tsinghua University, Beijing 100084; Wang, Lian-shan, E-mail: ls-wang@semi.ac.cn

In this paper, a theory is developed to study the anisotropic scattering effect of the inclined misfit dislocation on the two-dimensional electron gas in Al(In)GaN/GaN heterostructures. The inclined misfit dislocation, which differs from the well-known vertical threading dislocation, has a remarkable tilt angle from the vertical. The predicted electron mobility shows a remarkable anisotropy. It has a maximum mobility value along the direction perpendicular to the projection of the inclined dislocation line, and a minimum mobility value along the direction parallel to the projection. The degree of the anisotropic scattering effect will be even greater with the increase of themore » tilt angle.« less

Matric potential

Treesearch

Melvin T. Tyree

2003-01-01

Matric potential, r, is a component of water potential, ?, but has different meanings in plant physiology vs. soil science. A rigorous definition of r requires a reference to principles of thermodynamics (both classical and irreversible thermodynamics). A rigorous treatment is beyond the scope of this brief overview. Readers...

Plane wave packet formulation of atom-plus-diatom quantum reactive scattering.

PubMed

Althorpe, Stuart C

2004-07-15

We recently interpreted several reactive scattering experiments using a plane wave packet (PWP) formulation of quantum scattering theory [see, e.g., S. C. Althorpe, F. Fernandez-Alonso, B. D. Bean, J. D. Ayers, A. E. Pomerantz, R. N. Zare, and E. Wrede, Nature (London) 416, 67 (2002)]. This paper presents the first derivation of this formulation for atom-plus-diatom reactive scattering, and explains its relation to conventional time-independent reactive scattering. We generalize recent results for spherical-particle scattering [S. C. Althorpe, Phys. Rev. A 69, 042702 (2004)] to atom-rigid-rotor scattering in the space-fixed frame, atom-rigid-rotor scattering in the body-fixed frame, and finally A+BC rearrangement scattering. The reactive scattering is initiated by a plane wave packet, describing the A+BC reagents in center-of-mass scattering coordinates, and is detected by projecting onto a series of AC+B (or AB+C) plane wave "probe" packets. The plane wave packets are localized at the closest distance from the scattering center at which the interaction potential can be neglected. The time evolution of the initial plane wave packet provides a clear visualization of the scattering into space of the reaction products. The projection onto the probe packets yields the time-independent, state-to-state scattering amplitude, and hence the differential cross section. We explain how best to implement the PWP approach in a numerical computation, and illustrate this with a detailed application to the H+D2 reaction. (c) 2004 American Institute of Physics

Visualization of N-body Simulations in Virtual Worlds

NASA Astrophysics Data System (ADS)

Knop, Robert A.; Ames, J.; Djorgovski, G.; Farr, W.; Hut, P.; Johnson, A.; McMillan, S.; Nakasone, A.; Vesperini, E.

2010-01-01

We report on work to use virtual worlds for visualizing the results of N-body calculations, on three levels. First, we have written a demonstration 3-body solver entirely in the scripting language of the popularly used virtual world Second Life. Second, we have written a physics module for the open source virtual world OpenSim that performs N-body calculations as the physics engine for the server, allowing natural 3-d visualization of the solution as the solution is being performed. Finally, we give an initial report on the potential use of virtual worlds to visualize calculations which have previously been performed, or which are being performed in other processes and reported to the virtual world server. This work has been performed as part of the Meta-Institute of Computational Astrophysics (MICA). http://www.mica-vw.org

Thomson scattering density calibration by Rayleigh and rotational Raman scattering on NSTX.

PubMed

LeBlanc, B P

2008-10-01

The multipoint Thomson scattering diagnostic measures the profiles of the electron temperature T(e)(R) and density n(e)(R) on the horizontal midplane of NSTX. Normal operation makes use of Rayleigh scattering in nitrogen or argon to derive the density profile. While the Rayleigh scattering n(e)(R) calibration has been validated by comparison to other density measurements and through its correlation with plasma phenomena, it does require dedicated detectors at the laser wavelength in this filter polychromator based diagnostic. The presence of dust and/or stray laser light precludes routine use of these dedicated spectral channels for Thomson scattering measurement. Hence it is of interest to investigate the use of Raman scattering in nitrogen for the purpose of density calibration since it could free up detection equipment, which could then be used for the instrumentation of additional radial channels. In this paper the viewing optics "geometrical factor" profiles obtained from Rayleigh and Raman scattering are compared. While both techniques agree nominally, residual effects on the order of 10% remain and will be discussed.

Super central configurations of the n-body problem

NASA Astrophysics Data System (ADS)

Xie, Zhifu

2010-04-01

In this paper, we consider the inverse problem of central configurations of the n-body problem. For a given q =(q1,q2,…,qn)ε(Rd)n, let S(q ) be the admissible set of masses by S(q )={m =(m1,…,mn)∣miεR+, q is a central configurationfor m}. For a given m εS(q), let Sm(q) be the permutational admissible set about m =(m1,m2,…,mn) by Sm(q)={m'∣m'εS(q), m'≠m and m' is apermutation of m}. Here, q is called a super central configuration if there exists m such that Sm(q) is nonempty. For any q in the planar four-body problem, q is not a super central configuration as an immediate consequence of a theorem proved by MacMillan and Bartky ["Permanent configurations in the problem of four bodies," Trans. Am. Math. Soc. 34, 838 (1932)]. The main discovery in this paper is the existence of super central configurations in the collinear three-body problem. We proved that for any q in the collinear three-body problem and any m εS(q), Sm(q) has at most one element and the detailed classification of Sm(q) is provided.

Breakdown of Universality for Unequal-Mass Fermi Gases with Infinite Scattering Length

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blume, D.; Daily, K. M.

We treat small trapped unequal-mass two-component Fermi gases at unitarity within a nonperturbative microscopic framework and investigate the system properties as functions of the mass ratio {kappa}, and the numbers N{sub 1} and N{sub 2} of heavy and light fermions. While equal-mass Fermi gases with infinitely large interspecies s-wave scattering length a{sub s} are universal, we find that unequal-mass Fermi gases are, for sufficiently large {kappa} and in the regime where Efimov physics is absent, not universal. In particular, the (N{sub 1},N{sub 2})=(2,1) and (3, 1) systems exhibit three-body and four-body resonances at {kappa}=12.314(2) and 10.4(2), respectively, as well asmore » surprisingly large finite-range effects. These findings have profound implications for ongoing experimental efforts and quantum simulation proposals that utilize unequal-mass atomic Fermi gases.« less

Coherent backscattering of light by complex random media of spherical scatterers: numerical solution

NASA Astrophysics Data System (ADS)

Muinonen, Karri

2004-07-01

Novel Monte Carlo techniques are described for the computation of reflection coefficient matrices for multiple scattering of light in plane-parallel random media of spherical scatterers. The present multiple scattering theory is composed of coherent backscattering and radiative transfer. In the radiative transfer part, the Stokes parameters of light escaping from the medium are updated at each scattering process in predefined angles of emergence. The scattering directions at each process are randomized using probability densities for the polar and azimuthal scattering angles: the former angle is generated using the single-scattering phase function, whereafter the latter follows from Kepler's equation. For spherical scatterers in the Rayleigh regime, randomization proceeds semi-analytically whereas, beyond that regime, cubic spline presentation of the scattering matrix is used for numerical computations. In the coherent backscattering part, the reciprocity of electromagnetic waves in the backscattering direction allows the renormalization of the reversely propagating waves, whereafter the scattering characteristics are computed in other directions. High orders of scattering (~10 000) can be treated because of the peculiar polarization characteristics of the reverse wave: after a number of scatterings, the polarization state of the reverse wave becomes independent of that of the incident wave, that is, it becomes fully dictated by the scatterings at the end of the reverse path. The coherent backscattering part depends on the single-scattering albedo in a non-monotonous way, the most pronounced signatures showing up for absorbing scatterers. The numerical results compare favourably to the literature results for nonabsorbing spherical scatterers both in and beyond the Rayleigh regime.

Oligo p-Phenylenevinylene Derivatives as Electron Transfer Matrices for UV-MALDI

NASA Astrophysics Data System (ADS)

Castellanos-García, Laura J.; Agudelo, Brian Castro; Rosales, Hernando F.; Cely, Melissa; Ochoa-Puentes, Christian; Blanco-Tirado, Cristian; Sierra, Cesar A.; Combariza, Marianny Y.

2017-12-01

Phenylenevinylene oligomers (PVs) have outstanding photophysical characteristics for applications in the growing field of organic electronics. Yet, PVs are also versatile molecules, the optical and physicochemical properties of which can be tuned by manipulation of their structure. We report the synthesis, photophysical, and MS characterization of eight PV derivatives with potential value as electron transfer (ET) matrices for UV-MALDI. UV-vis analysis show the presence of strong characteristic absorption bands in the UV region and molar absorptivities at 355 nm similar or higher than those of traditional proton (CHCA) and ET (DCTB) MALDI matrices. Most of the PVs exhibit non-radiative quantum yields (φ) above 0.5, indicating favorable thermal decay. Ionization potential values (IP) for PVs, calculated by the Electron Propagator Theory (EPT), range from 6.88 to 7.96 eV, making these oligomers good candidates as matrices for ET ionization. LDI analysis of PVs shows only the presence of radical cations (M+.) in positive ion mode and absence of clusters, adducts, or protonated species; in addition, M+. threshold energies for PVs are lower than for DCTB. We also tested the performance of four selected PVs as ET MALDI matrices for analytes ranging from porphyrins and phthalocyanines to polyaromatic compounds. Two of the four PVs show S/N enhancement of 1961% to 304% in comparison to LDI, and laser energy thresholds from 0.17 μJ to 0.47 μJ compared to 0.58 μJ for DCTB. The use of PV matrices also results in lower LODs (low fmol range) whereas LDI LODs range from pmol to nmol. [Figure not available: see fulltext.

Accelerator-feasible N -body nonlinear integrable system

DOE PAGES

Danilov, V.; Nagaitsev, S.

2014-12-23

Nonlinear N-body integrable Hamiltonian systems, where N is an arbitrary number, attract the attention of mathematical physicists for the last several decades, following the discovery of some number of these systems. This research presents a new integrable system, which can be realized in facilities such as particle accelerators. This feature makes it more attractive than many of the previous such systems with singular or unphysical forces.

Resonant nuclear scattering of synchrotron radiation: Detector development and specular scattering from a thin layer of {sup 57}Fe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baron, A.Q.R.

1995-04-01

This thesis explores resonant nudear scattering of synchrotron radiation. An introductory chapter describes some useful concepts, such as speedup and coherent enhancement, in the context of some basic physical principles. Methods of producing highly monochromatic synchrotron beams usmg either electronic or nuclear scattering are also discussed. The body of the thesis concentrates on detector development and specular scattering from iynthetic layered materials. A detector employing n-dcrochannel plate electron multipliers is shown to have good ({approximately}50%) effidency for detecting 14.4 key x-rays incident at small ({approximately}0.5 degree) grazing angles onto Au or CsI photocathodes. However, being complicated to use, it wasmore » replaced with a large area (>=lan2) avalanche photodiode (APD) detector. The APD`s are simpler to use and have comparable (30--70%) efficiencies at 14.4 key, subnanosecond time resolution, large dynan-dc range (usable at rates up to {approximately}10{sup 8} photons/second) and low (<{approximately}0.01 cts/sec) background rates. Maxwell`s equations are used to derive the specular x-ray reflectivity of layered materials with resonant transitions and complex polarization dependencies. The effects of interfadal roughness are treated with some care, and the distorted wave Born approximation (DWBA) used to describe electronic scattering is generalized to the nuclear case. The implications of the theory are discussed in the context of grazing incidence measurements with emphasis on the kinematic and dynamical aspects of the scattering.« less

Computation of eigenpairs of Ax = lambda Bx for vibrations of spinning deformable bodies

NASA Technical Reports Server (NTRS)

Utku, S.; Clemente, J. L. M.

1984-01-01

It is shown that, when linear theory is used, the general eigenvalue problem related with the free vibrations of spinning deformable bodies is of the type AX = lambda Bx, where A is Hermitian, and B is real positive definite. Since the order n of the matrices may be large, and A and B are banded or block banded, due to the economics of the numerical solution, one is interested in obtaining only those eigenvalues which fall within the frequency band of interest of the problem. The paper extends the well known method of bisections and iteration of R to the n power to n dimensional complex spaces, i.e., to C to the n power, so that it can be applied to the present problem.

Homology search with binary and trinary scoring matrices.

PubMed

Smith, Scott F

2006-01-01

Protein homology search can be accelerated with the use of bit-parallel algorithms in conjunction with constraints on the values contained in the scoring matrices. Trinary scoring matrices (containing only the values -1, 0, and 1) allow for significant acceleration without significant reduction in the receiver operating characteristic (ROC) score of a Smith-Waterman search. Binary scoring matrices (containing the values 0 and 1) result in some reduction in ROC score, but result in even more acceleration. Binary scoring matrices and five-bit saturating scores can be used for fast prefilters to the Smith-Waterman algorithm.

Scattering amplitude and bosonization duality in general Chern-Simons vector models

NASA Astrophysics Data System (ADS)

Yokoyama, Shuichi

2016-09-01

We present the exact large N calculus of four point functions in general Chern-Simons bosonic and fermionic vector models. Applying the LSZ formula to the four point function we determine the two body scattering amplitudes in these theories taking a special care for a non-analytic term to achieve unitarity in the singlet channel. We show that the S-matrix enjoys the bosonization duality, an unusual crossing relation and a non-relativistic reduction to Aharonov-Bohm scattering. We also argue that the S-matrix develops a pole in a certain range of coupling constants, which disappears in the range where the theory reduces to the Chern-Simons theory interacting with free fermions.

Development of KSTAR Thomson scattering system.

PubMed

Lee, J H; Oh, S T; Wi, H M

2010-10-01

To measure the electron temperature (T(e)) and electron density (n(e)) profiles in the Korean Superconducting Tokamak Advanced Research (KSTAR) device for the KSTAR third campaign (September 2010), we designed and installed a Thomson scattering system. The KSTAR Thomson scattering system is designed as a tangential Thomson scattering system and utilizes the N-, L-, and B-ports. The N-port is designed for the collection optics with a cassette system, the L-port is the laser input port, and the B-port is the location of the beam dump. In this paper, we will describe the final design of the KSTAR Thomson scattering system.

Virial expansion for almost diagonal random matrices

NASA Astrophysics Data System (ADS)

Yevtushenko, Oleg; Kravtsov, Vladimir E.

2003-08-01

Energy level statistics of Hermitian random matrices hat H with Gaussian independent random entries Higeqj is studied for a generic ensemble of almost diagonal random matrices with langle|Hii|2rangle ~ 1 and langle|Hi\

On physical optics for calculating scattering from coated bodies

NASA Technical Reports Server (NTRS)

Baldauf, J.; Lee, S. W.; Ling, H.; Chou, R.

1989-01-01

The familiar physical optics (PO) approximation is no longer valid when the perfectly conducting scatterer is coated with dielectric material. This paper reviews several possible PO formulations. By comparing the PO formulation with the moment method solution based on the impedance boundary condition for the case of the coated cone-sphere, a PO formulation using both electric and magnetic currents consistently gives the best numerical results. Comparisons of the exact moment method with the PO formulations using the impedance boundary condition and the PO formulation using the Fresnel reflection coefficient for the case of scattering from the cone-ellipsoid demonstrate that the Fresnel reflection coefficient gives the best numerical results in general.

Particle Number Dependence of the N-body Simulations of Moon Formation

NASA Astrophysics Data System (ADS)

Sasaki, Takanori; Hosono, Natsuki

2018-04-01

The formation of the Moon from the circumterrestrial disk has been investigated by using N-body simulations with the number N of particles limited from 104 to 105. We develop an N-body simulation code on multiple Pezy-SC processors and deploy Framework for Developing Particle Simulators to deal with large number of particles. We execute several high- and extra-high-resolution N-body simulations of lunar accretion from a circumterrestrial disk of debris generated by a giant impact on Earth. The number of particles is up to 107, in which 1 particle corresponds to a 10 km sized satellitesimal. We find that the spiral structures inside the Roche limit radius differ between low-resolution simulations (N ≤ 105) and high-resolution simulations (N ≥ 106). According to this difference, angular momentum fluxes, which determine the accretion timescale of the Moon also depend on the numerical resolution.

Determination of arsenic species in solid matrices utilizing supercritical fluid extraction coupled with gas chromatography after derivatization with thioglycolic acid n-butyl ester.

PubMed

Wang, Zhifeng; Cui, Zhaojie

2016-12-01

A method using derivatization and supercritical fluid extraction coupled with gas chromatography was developed for the analysis of dimethylarsinate, monomethylarsonate and inorganic arsenic simultaneously in solid matrices. Thioglycolic acid n-butyl ester was used as a novel derivatizing reagent. A systematic discussion was made to investigate the effects of pressure, temperature, flow rate of the supercritical CO 2 , extraction time, concentration of the modifier, and microemulsion on extraction efficiency. The application for real environmental samples was also studied. Results showed that thioglycolic acid n-butyl ester was an effective derivatizing reagent that could be applied for arsenic speciation. Using methanol as modifier of the supercritical CO 2 can raise the extraction efficiency, which can be further enhanced by adding a microemulsion that contains Triton X-405. The optimum extraction conditions were: 25 MPa, 90°C, static extraction for 10 min, dynamic extraction for 25 min with a flow rate of 2.0 mL/min of supercritical CO 2 modified by 5% v/v methanol and microemulsion. The detection limits of dimethylarsinate, monomethylarsonate, and inorganic arsenic in solid matrices were 0.12, 0.26, and 1.1 mg/kg, respectively. The optimized method was sensitive, convenient, and reliable for the extraction and analysis of different arsenic species in solid samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Off-energy-shell p-p scattering at sub-Coulomb energies via the Trojan horse method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tumino, A.; Dipartimento di Metodologie Fisiche e Chimiche per l'Ingegneria, Universita di Catania, Catania; Universita Kore di Enna, Enna

2008-12-15

Two-proton scattering at sub-Coulomb energies has been measured indirectly via the Trojan horse method applied to the p + d{yields}p + p + n reaction to investigate off-energy shell effects for scattering processes. The three-body experiment was performed at 5 and 4.7 MeV corresponding to a p-p relative energy ranging from 80 to 670 keV. The free p-p cross section exhibits a deep minimum right within this relative energy region due to Coulomb plus nuclear destructive interference. No minimum occurs instead in the Trojan horse p-p cross section, which was extracted by employing a simple plane-wave impulse approximation. A detailedmore » formalism was developed to build up the expression of the theoretical half-off-shell p-p cross section. Its behavior agrees with the Trojan horse data and in turn formally fits the n-n, n-p, and nuclear p-p cross sections given the fact that in its expression the Coulomb amplitude is negligible with respect to the nuclear one. These results confirm the Trojan horse suppression of the Coulomb amplitude for scattering due to the off-shell character of the process.« less

Generalized Rayleigh scattering. I. Basic theory.

NASA Astrophysics Data System (ADS)

Ivanov, V. V.

1995-11-01

The classsical problem of multiple molecular (in particular, Rayleigh) scattering in plane-parallel atmospheres is considered from a somewhat broader viewpoint than usual. The general approach and ideology are borrowed from non-LTE line formation theory. The main emphasis is on the depth dependence of the corresponding source matrix rather than on the emergent radiation. We study the azimuth-averaged radiation field of polarized radiation in a semi-infinite atmosphere with embedded primary sources. The corresponding 2x2 phase matrix of molecular scattering is P=(1-W) P_I_+W P_R_, where P_I_ and P_R_ are the phase matrices of the scalar isotropic scattering and of the Rayleigh scattering, respectively, and W is the depolarization parameter. Contrary to the usual assumption that W{in}[0,1], we assume W{in} [0,{infinity}) and call this generalized Rayleigh scattering (GRS). Using the factorization of P which is intimately related to its diadic expansion, we reduce the problem to an integral equation for the source matrix S(τ) with a matrix displacement kernel. In operator form this equation is S={LAMBDA}S+S^*^, where {LAMBDA} is the matrix {LAMBDA}-operator and S^*^ is the primary source term. This leads to a new concept, the matrix albedo of single scattering λ =diag(λ_I_,λ_Q_), where λ_I_ is the usual (scalar) single scattering albedo and λ_Q_=0.7Wλ_I_. Its use enables one to formulate matrix equivalents of many of the results of the scalar theory in exactly the same form as in the scalar case. Of crucial importance is the matrix equivalent of the sqrt(ɛ) law of the scalar theory. Another useful new concept is the λ-plane, i.e., the plane with the axes (λ_I_,λ_Q_). Systematic use of the matrix sqrt(ɛ) law and of the λ-plane proved to be a useful instrument in classifying various limiting and particular cases of GRS and in discussing numerical data on the matrix source functions (to be given in Paper II of the series).

Synchronous correlation matrices and Connes’ embedding conjecture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dykema, Kenneth J., E-mail: kdykema@math.tamu.edu; Paulsen, Vern, E-mail: vern@math.uh.edu

In the work of Paulsen et al. [J. Funct. Anal. (in press); preprint arXiv:1407.6918], the concept of synchronous quantum correlation matrices was introduced and these were shown to correspond to traces on certain C*-algebras. In particular, synchronous correlation matrices arose in their study of various versions of quantum chromatic numbers of graphs and other quantum versions of graph theoretic parameters. In this paper, we develop these ideas further, focusing on the relations between synchronous correlation matrices and microstates. We prove that Connes’ embedding conjecture is equivalent to the equality of two families of synchronous quantum correlation matrices. We prove thatmore » if Connes’ embedding conjecture has a positive answer, then the tracial rank and projective rank are equal for every graph. We then apply these results to more general non-local games.« less

JANUS: a bit-wise reversible integrator for N-body dynamics

NASA Astrophysics Data System (ADS)

Rein, Hanno; Tamayo, Daniel

2018-01-01

Hamiltonian systems such as the gravitational N-body problem have time-reversal symmetry. However, all numerical N-body integration schemes, including symplectic ones, respect this property only approximately. In this paper, we present the new N-body integrator JANUS , for which we achieve exact time-reversal symmetry by combining integer and floating point arithmetic. JANUS is explicit, formally symplectic and satisfies Liouville's theorem exactly. Its order is even and can be adjusted between two and ten. We discuss the implementation of JANUS and present tests of its accuracy and speed by performing and analysing long-term integrations of the Solar system. We show that JANUS is fast and accurate enough to tackle a broad class of dynamical problems. We also discuss the practical and philosophical implications of running exactly time-reversible simulations.

Inclusion of electron correlation for the target wave function in low-energy e sup minus +N sub 2 scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, H.; Pal, S.; Riss, U.V.

1992-07-01

The interaction of a scattering electron with a correlated but frozen'' target may be called the correlated static-exchange interaction. There are two prior investigations (J.R. Rumble, W.J. Stevens, and D. Truhlar, J. Phys. B 17, 3151 (1984); C Weatherford, F.B. Brown, and A. Temkin, Phys. Rev. A 35, 4561 (1987)) on scattering off the correlated static-exchange potential. Both of these investigations concentrated on {ital e}{sup {minus}}+N{sub 2} scattering, and both have found that the correlated static-exchange potential is less attractive than the static-exchange potential. We will show, however, that the correlated static-exchange potential is more attractive than the static-exchange one---atmore » least for {ital e}{sup {minus}}+N{sub 2} scattering in {sup 2}{Pi}{sub {ital g}} symmetry. The two prior investigations were misled by an improper degree of correlation and by an improper treatment of the exchange.« less

Noisy covariance matrices and portfolio optimization II

NASA Astrophysics Data System (ADS)

Pafka, Szilárd; Kondor, Imre

2003-03-01

Recent studies inspired by results from random matrix theory (Galluccio et al.: Physica A 259 (1998) 449; Laloux et al.: Phys. Rev. Lett. 83 (1999) 1467; Risk 12 (3) (1999) 69; Plerou et al.: Phys. Rev. Lett. 83 (1999) 1471) found that covariance matrices determined from empirical financial time series appear to contain such a high amount of noise that their structure can essentially be regarded as random. This seems, however, to be in contradiction with the fundamental role played by covariance matrices in finance, which constitute the pillars of modern investment theory and have also gained industry-wide applications in risk management. Our paper is an attempt to resolve this embarrassing paradox. The key observation is that the effect of noise strongly depends on the ratio r= n/ T, where n is the size of the portfolio and T the length of the available time series. On the basis of numerical experiments and analytic results for some toy portfolio models we show that for relatively large values of r (e.g. 0.6) noise does, indeed, have the pronounced effect suggested by Galluccio et al. (1998), Laloux et al. (1999) and Plerou et al. (1999) and illustrated later by Laloux et al. (Int. J. Theor. Appl. Finance 3 (2000) 391), Plerou et al. (Phys. Rev. E, e-print cond-mat/0108023) and Rosenow et al. (Europhys. Lett., e-print cond-mat/0111537) in a portfolio optimization context, while for smaller r (around 0.2 or below), the error due to noise drops to acceptable levels. Since the length of available time series is for obvious reasons limited in any practical application, any bound imposed on the noise-induced error translates into a bound on the size of the portfolio. In a related set of experiments we find that the effect of noise depends also on whether the problem arises in asset allocation or in a risk measurement context: if covariance matrices are used simply for measuring the risk of portfolios with a fixed composition rather than as inputs to optimization, the

Time series, correlation matrices and random matrix models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinayak; Seligman, Thomas H.

2014-01-08

In this set of five lectures the authors have presented techniques to analyze open classical and quantum systems using correlation matrices. For diverse reasons we shall see that random matrices play an important role to describe a null hypothesis or a minimum information hypothesis for the description of a quantum system or subsystem. In the former case various forms of correlation matrices of time series associated with the classical observables of some system. The fact that such series are necessarily finite, inevitably introduces noise and this finite time influence lead to a random or stochastic component in these time series.more » By consequence random correlation matrices have a random component, and corresponding ensembles are used. In the latter we use random matrices to describe high temperature environment or uncontrolled perturbations, ensembles of differing chaotic systems etc. The common theme of the lectures is thus the importance of random matrix theory in a wide range of fields in and around physics.« less

Estimating soil matric potential in Owens Valley, California

USGS Publications Warehouse

Sorenson, Stephen K.; Miller, R.F.; Welch, M.R.; Groeneveld, D.P.; Branson, F.A.

1988-01-01

Much of the floor of the Owens Valley, California, is covered with alkaline scrub and alkaline meadow plant communities, whose existence is dependent partly on precipitation and partly on water infiltrated into the rooting zone from the shallow water table. The extent to which these plant communities are capable of adapting to and surviving fluctuations in the water table depends on physiological adaptations of the plants and on the water content, matric potential characteristics of the soils. Two methods were used to estimate soil matric potential in test sites in Owens Valley. The first was the filter-paper method, which uses water content of filter papers equilibrated to water content of soil samples taken with a hand auger. The other method of estimating soil matric potential was a modeling approach based on data from this and previous investigations. These data indicate that the base 10 logarithm of soil matric potential is a linear function of gravimetric soil water content for a particular soil. Estimates of soil water characteristic curves were made at two sites by averaging the gravimetric soil water content and soil matric potential values from multiple samples at 0.1 m depths derived by using the hand auger and filter paper method and entering these values in the soil water model. The characteristic curves then were used to estimate soil matric potential from estimates of volumetric soil water content derived from neutron-probe readings. Evaluation of the modeling technique at two study sites indicated that estimates of soil matric potential within 0.5 pF units of the soil matric potential value derived by using the filter paper method could be obtained 90 to 95% of the time in soils where water content was less than field capacity. The greatest errors occurred at depths where there was a distinct transition between soils of different textures. (Lantz-PTT)

Two-potential approach for electron-molecular collisions at intermediate and high energies - Application to e-N2 scatterings

NASA Technical Reports Server (NTRS)

Choi, B. H.; Poe, R. T.; Sun, J. C.; Shan, Y.

1979-01-01

A general theoretical approach is proposed for the calculation of elastic, vibrational, and rotational transitions for electron-molecule scattering at intermediate and high-electron-impact energies. In this formulation, contributions to the scattering process come from the incoherent sum of two dominant potentials: a short-range shielded nuclear Coulomb potential from individual atomic centers, and a permanent/induced long-range potential. Application to e-N2 scattering from 50-500 eV incident electron energies has yielded good agreement with absolutely calibrated experiments. Comparisons with other theoretical approaches are made. The physical picture as well as the general features of electron-molecule scattering process are discussed within the framework of the two-potential approach.

Tensor Sparse Coding for Positive Definite Matrices.

PubMed

Sivalingam, Ravishankar; Boley, Daniel; Morellas, Vassilios; Papanikolopoulos, Nikos

2013-08-02

In recent years, there has been extensive research on sparse representation of vector-valued signals. In the matrix case, the data points are merely vectorized and treated as vectors thereafter (for e.g., image patches). However, this approach cannot be used for all matrices, as it may destroy the inherent structure of the data. Symmetric positive definite (SPD) matrices constitute one such class of signals, where their implicit structure of positive eigenvalues is lost upon vectorization. This paper proposes a novel sparse coding technique for positive definite matrices, which respects the structure of the Riemannian manifold and preserves the positivity of their eigenvalues, without resorting to vectorization. Synthetic and real-world computer vision experiments with region covariance descriptors demonstrate the need for and the applicability of the new sparse coding model. This work serves to bridge the gap between the sparse modeling paradigm and the space of positive definite matrices.

Tensor sparse coding for positive definite matrices.

PubMed

Sivalingam, Ravishankar; Boley, Daniel; Morellas, Vassilios; Papanikolopoulos, Nikolaos

2014-03-01

In recent years, there has been extensive research on sparse representation of vector-valued signals. In the matrix case, the data points are merely vectorized and treated as vectors thereafter (for example, image patches). However, this approach cannot be used for all matrices, as it may destroy the inherent structure of the data. Symmetric positive definite (SPD) matrices constitute one such class of signals, where their implicit structure of positive eigenvalues is lost upon vectorization. This paper proposes a novel sparse coding technique for positive definite matrices, which respects the structure of the Riemannian manifold and preserves the positivity of their eigenvalues, without resorting to vectorization. Synthetic and real-world computer vision experiments with region covariance descriptors demonstrate the need for and the applicability of the new sparse coding model. This work serves to bridge the gap between the sparse modeling paradigm and the space of positive definite matrices.

Enantioselective determination of metconazole in multi matrices by high-performance liquid chromatography.

PubMed

He, Rujian; Fan, Jun; Tan, Qi; Lai, Yecai; Chen, Xiaodong; Wang, Tai; Jiang, Ying; Zhang, Yaomou; Zhang, Weiguang

2018-02-01

A reliable and effective HPLC analytical method has been developed to stereoselectively quantify metconazole in soil and flour matrices. Effects of polysaccharide chiral stationary phase, type and content of alcoholic modifier on separation of racemic metconazole have been discussed in detail. Resolution and quantitative determination of metconazole stereoisomers were performed by using an Enantiopak OD column, with the n-hexane-ethanol mixture (97:3, v/v) at the flow rate of 1.0mL/min. Then, extraction and cleanup procedures followed by the modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method were used for metconazole racemate in soil and flour matrices. The residual analysis method was validated. Good linearity (R 2 ≥ 0.9997) and recoveries (94.98-104.89%, RSD ≤ 2.0%) for four metconazole stereoisomers were obtained. In brief, this proposed method showed good accuracy and precision, which might be applied in enantioselective determination, residual quantitative analysis, and degradation of metconazole in food and environmental matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

Einstein-Yang-Mills scattering amplitudes from scattering equations

NASA Astrophysics Data System (ADS)

Cachazo, Freddy; He, Song; Yuan, Ellis Ye

2015-01-01

We present the building blocks that can be combined to produce tree-level S-matrix elements of a variety of theories with various spins mixed in arbitrary dimensions. The new formulas for the scattering of n massless particles are given by integrals over the positions of n points on a sphere restricted to satisfy the scattering equations. As applications, we obtain all single-trace amplitudes in Einstein-Yang-Mills (EYM) theory, and generalizations to include scalars. Also in EYM but extended by a B-field and a dilaton, we present all double-trace gluon amplitudes. The building blocks are made of Pfaffians and Parke-Taylor-like factors of subsets of particle labels.

Malware analysis using visualized image matrices.

PubMed

Han, KyoungSoo; Kang, BooJoong; Im, Eul Gyu

2014-01-01

This paper proposes a novel malware visual analysis method that contains not only a visualization method to convert binary files into images, but also a similarity calculation method between these images. The proposed method generates RGB-colored pixels on image matrices using the opcode sequences extracted from malware samples and calculates the similarities for the image matrices. Particularly, our proposed methods are available for packed malware samples by applying them to the execution traces extracted through dynamic analysis. When the images are generated, we can reduce the overheads by extracting the opcode sequences only from the blocks that include the instructions related to staple behaviors such as functions and application programming interface (API) calls. In addition, we propose a technique that generates a representative image for each malware family in order to reduce the number of comparisons for the classification of unknown samples and the colored pixel information in the image matrices is used to calculate the similarities between the images. Our experimental results show that the image matrices of malware can effectively be used to classify malware families both statically and dynamically with accuracy of 0.9896 and 0.9732, respectively.

Malware Analysis Using Visualized Image Matrices

PubMed Central

Im, Eul Gyu

2014-01-01

This paper proposes a novel malware visual analysis method that contains not only a visualization method to convert binary files into images, but also a similarity calculation method between these images. The proposed method generates RGB-colored pixels on image matrices using the opcode sequences extracted from malware samples and calculates the similarities for the image matrices. Particularly, our proposed methods are available for packed malware samples by applying them to the execution traces extracted through dynamic analysis. When the images are generated, we can reduce the overheads by extracting the opcode sequences only from the blocks that include the instructions related to staple behaviors such as functions and application programming interface (API) calls. In addition, we propose a technique that generates a representative image for each malware family in order to reduce the number of comparisons for the classification of unknown samples and the colored pixel information in the image matrices is used to calculate the similarities between the images. Our experimental results show that the image matrices of malware can effectively be used to classify malware families both statically and dynamically with accuracy of 0.9896 and 0.9732, respectively. PMID:25133202

A model for attenuation and scattering in the Earth's crust

NASA Astrophysics Data System (ADS)

Toksöz, M. Nafi; Dainty, Anton M.; Reiter, Edmund; Wu, Ru-Shan

1988-03-01

The mechanisms contributing to the attenuation of earthquake ground motion in the distance range of 10 to 200 km are studied with the aid of laboratory data, coda waves Rg attenuation, strong motion attenuation measurements in the northeast United States and Canada, and theoretical models. The frequency range 1 10 Hz has been studied. The relative contributions to attenuation of anelasticity of crustal rocks (constant Q), fluid flow and scattering are evaluated. Scattering is found to be strong with an albedo B 0=0.8 0.9 and a scattering extinction length of 17 32 km. The albedo is defined as the ratio of the total extinction length to the scattering extinction length. The Rg results indicate that Q increases with depth in the upper kilometer or two of the crust, at least in New England. Coda Q appears to be equivalent to intrinsic (anelastic) Q and indicates that this Q increases with frequency as Q=Q o f n , where n is in the range of 0.2 0.9. The intrinsic attenuation in the crust can be explained by a high constant Q (500≤ Q o≤2000) and a frequency dependent mechanism most likely due to fluid effects in rocks and cracks. A fluid-flow attenuation model gives a frequency dependence ( Q≃ Q o f 0.5) similar to those determined from the analysis of coda waves of regional seismograms. Q is low near the surface and high in the body of the crust.

Evaluation of scatter limitation correction: a new method of correcting photopenic artifacts caused by patient motion during whole-body PET/CT imaging.

PubMed

Miwa, Kenta; Umeda, Takuro; Murata, Taisuke; Wagatsuma, Kei; Miyaji, Noriaki; Terauchi, Takashi; Koizumi, Mitsuru; Sasaki, Masayuki

2016-02-01

Overcorrection of scatter caused by patient motion during whole-body PET/computed tomography (CT) imaging can induce the appearance of photopenic artifacts in the PET images. The present study aimed to quantify the accuracy of scatter limitation correction (SLC) for eliminating photopenic artifacts. This study analyzed photopenic artifacts in (18)F-fluorodeoxyglucose ((18)F-FDG) PET/CT images acquired from 12 patients and from a National Electrical Manufacturers Association phantom with two peripheral plastic bottles that simulated the human body and arms, respectively. The phantom comprised a sphere (diameter, 10 or 37 mm) containing fluorine-18 solutions with target-to-background ratios of 2, 4, and 8. The plastic bottles were moved 10 cm posteriorly between CT and PET acquisitions. All PET data were reconstructed using model-based scatter correction (SC), no scatter correction (NSC), and SLC, and the presence or absence of artifacts on the PET images was visually evaluated. The SC and SLC images were also semiquantitatively evaluated using standardized uptake values (SUVs). Photopenic artifacts were not recognizable in any NSC and SLC image from all 12 patients in the clinical study. The SUVmax of mismatched SLC PET/CT images were almost equal to those of matched SC and SLC PET/CT images. Applying NSC and SLC substantially eliminated the photopenic artifacts on SC PET images in the phantom study. SLC improved the activity concentration of the sphere for all target-to-background ratios. The highest %errors of the 10 and 37-mm spheres were 93.3 and 58.3%, respectively, for mismatched SC, and 73.2 and 22.0%, respectively, for mismatched SLC. Photopenic artifacts caused by SC error induced by CT and PET image misalignment were corrected using SLC, indicating that this method is useful and practical for clinical qualitative and quantitative PET/CT assessment.

Introducing capillary electrophoresis with laser-induced fluorescence (CE-LIF) as a potential analysis and quantification tool for galactooligosaccharides extracted from complex food matrices.

PubMed

Albrecht, Simone; Schols, Henk A; Klarenbeek, Bert; Voragen, Alphons G J; Gruppen, Harry

2010-03-10

The analysis and quantification of (galacto)oligosaccharides from food matrices demands both a reproducible extraction method as well as a sensitive and accurate analytical method. Three typical matrices, namely, infant formula, fruit juice, and a maltodextrin-rich preparation, to which a commercial galactooligosaccharide mixture was added in a product concentration range from 1.25 to 30%, served as model substrates. Solid-phase extraction on graphitized carbon material upon enzymatic amyloglucosidase pretreatment enabled a good recovery and a selective purification of the different galactooligosaccharide structures from the exceeding amounts of particularly lactose and maltodextrins. With the implementation of capillary electrophoresis in combination with laser-induced fluorescence (CE-LIF) detection, a new possibility facilitating a sensitive qualitative and quantitative determination of the galactooligosaccharide contents in the different food matrices is outlined. Simultaneous monitoring and quantifying prebiotic oligosaccharides embedded in food matrices presents a promising and important step toward an efficient monitoring of individual oligosaccharides and is of interest for research areas dealing with small quantities of oligosaccharides embedded in complex matrices, e.g., body liquids.

Acoustic Coherent Backscatter Enhancement from Aggregations of Point Scatterers

DTIC Science & Technology

2015-09-30

and far-field acoustic multiple scattering from two- and now three-dimensional aggregations of omnidirectional point scatterers to determine the...an aggregation of omnidirectional point scatterers [1]. If ψ(r) is the harmonic acoustic pressure field at frequency ω at the point r and ψ0(r) is... scattered field and is given by the sum in (1), N is the number of scatterers , gn is the scattering coefficient of the nth scatterer , ψn(rn) is the field

A model for pion-pion scattering in large- N QCD

NASA Astrophysics Data System (ADS)

Veneziano, G.; Yankielowicz, S.; Onofri, E.

2017-04-01

Following up on recent work by Caron-Huot et al. we consider a generalization of the old Lovelace-Shapiro model as a toy model for ππ scattering satisfying (most of) the properties expected to hold in ('t Hooft's) large- N limit of massless QCD. In particular, the model has asymptotically linear and parallel Regge trajectories at positive t, a positive leading Regge intercept α 0 < 1, and an effective bending of the trajectories in the negative- t region producing a fixed branch point at J = 0 for t < t 0 < 0. Fixed (physical) angle scattering can be tuned to match the power-like behavior (including logarithmic corrections) predicted by perturbative QCD: A( s, t) ˜ s - β log( s)-γ F ( θ). Tree-level unitarity (i.e. positivity of residues for all values of s and J ) imposes strong constraints on the allowed region in the α0- β-γ parameter space, which nicely includes a physically interesting region around α 0 = 0 .5, β = 2 and γ = 3. The full consistency of the model would require an extension to multi-pion processes, a program we do not undertake in this paper.

Computation of transform domain covariance matrices

NASA Technical Reports Server (NTRS)

Fino, B. J.; Algazi, V. R.

1975-01-01

It is often of interest in applications to compute the covariance matrix of a random process transformed by a fast unitary transform. Here, the recursive definition of fast unitary transforms is used to derive recursive relations for the covariance matrices of the transformed process. These relations lead to fast methods of computation of covariance matrices and to substantial reductions of the number of arithmetic operations required.

Body frame close coupling wave packet approach to gas phase atom-rigid rotor inelastic collisions

NASA Technical Reports Server (NTRS)

Sun, Y.; Judson, R. S.; Kouri, D. J.

1989-01-01

The close coupling wave packet (CCWP) method is formulated in a body-fixed representation for atom-rigid rotor inelastic scattering. For J greater than j-max (where J is the total angular momentum and j is the rotational quantum number), the computational cost of propagating the coupled channel wave packets in the body frame is shown to scale approximately as N exp 3/2, where N is the total number of channels. For large numbers of channels, this will be much more efficient than the space frame CCWP method previously developed which scales approximately as N-squared under the same conditions.

Decision Matrices: Tools to Enhance Middle School Engineering Instruction

ERIC Educational Resources Information Center

Gonczi, Amanda L.; Bergman, Brenda G.; Huntoon, Jackie; Allen, Robin; McIntyre, Barb; Turner, Sheri; Davis, Jen; Handler, Rob

2017-01-01

Decision matrices are valuable engineering tools. They allow engineers to objectively examine solution options. Decision matrices can be incorporated in K-12 classrooms to support authentic engineering instruction. In this article we provide examples of how decision matrices have been incorporated into 6th and 7th grade classrooms as part of an…

19 CFR 10.90 - Master records and metal matrices.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 19 Customs Duties 1 2011-04-01 2011-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301, containing...

19 CFR 10.90 - Master records and metal matrices.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 19 Customs Duties 1 2013-04-01 2013-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301, containing...

19 CFR 10.90 - Master records and metal matrices.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 19 Customs Duties 1 2014-04-01 2014-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301, containing...

19 CFR 10.90 - Master records and metal matrices.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 19 Customs Duties 1 2012-04-01 2012-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301, containing...

19 CFR 10.90 - Master records and metal matrices.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 1 2010-04-01 2010-04-01 false Master records and metal matrices. 10.90 Section... Master Records, and Metal Matrices § 10.90 Master records and metal matrices. (a) Consumption entries... made, of each master record or metal matrix covered thereby. (c) A bond on Customs Form 301, containing...

Nonorthogonal orbital based N-body reduced density matrices and their applications to valence bond theory. I. Hamiltonian matrix elements between internally contracted excited valence bond wave functions

NASA Astrophysics Data System (ADS)

Chen, Zhenhua; Chen, Xun; Wu, Wei

2013-04-01

In this series, the n-body reduced density matrix (n-RDM) approach for nonorthogonal orbitals and their applications to ab initio valence bond (VB) methods are presented. As the first paper of this series, Hamiltonian matrix elements between internally contracted VB wave functions are explicitly provided by means of nonorthogonal orbital based RDM approach. To this end, a more generalized Wick's theorem, called enhanced Wick's theorem, is presented both in arithmetical and in graphical forms, by which the deduction of expressions for the matrix elements between internally contracted VB wave functions is dramatically simplified, and the matrix elements are finally expressed in terms of tensor contractions of electronic integrals and n-RDMs of the reference VB self-consistent field wave function. A string-based algorithm is developed for the purpose of evaluating n-RDMs in an efficient way. Using the techniques presented in this paper, one is able to develop new methods and efficient algorithms for nonorthogonal orbital based many-electron theory much easier than by use of the first quantized formulism.

Laminin active peptide/agarose matrices as multifunctional biomaterials for tissue engineering.

PubMed

Yamada, Yuji; Hozumi, Kentaro; Aso, Akihiro; Hotta, Atsushi; Toma, Kazunori; Katagiri, Fumihiko; Kikkawa, Yamato; Nomizu, Motoyoshi

2012-06-01

Cell adhesive peptides derived from extracellular matrix components are potential candidates to afford bio-adhesiveness to cell culture scaffolds for tissue engineering. Previously, we covalently conjugated bioactive laminin peptides to polysaccharides, such as chitosan and alginate, and demonstrated their advantages as biomaterials. Here, we prepared functional polysaccharide matrices by mixing laminin active peptides and agarose gel. Several laminin peptide/agarose matrices showed cell attachment activity. In particular, peptide AG73 (RKRLQVQLSIRT)/agarose matrices promoted strong cell attachment and the cell behavior depended on the stiffness of agarose matrices. Fibroblasts formed spheroid structures on the soft AG73/agarose matrices while the cells formed a monolayer with elongated morphologies on the stiff matrices. On the stiff AG73/agarose matrices, neuronal cells extended neuritic processes and endothelial cells formed capillary-like networks. In addition, salivary gland cells formed acini-like structures on the soft matrices. These results suggest that the peptide/agarose matrices are useful for both two- and three-dimensional cell culture systems as a multifunctional biomaterial for tissue engineering. Copyright © 2012 Elsevier Ltd. All rights reserved.

An isogeometric boundary element method for electromagnetic scattering with compatible B-spline discretizations

NASA Astrophysics Data System (ADS)

Simpson, R. N.; Liu, Z.; Vázquez, R.; Evans, J. A.

2018-06-01

We outline the construction of compatible B-splines on 3D surfaces that satisfy the continuity requirements for electromagnetic scattering analysis with the boundary element method (method of moments). Our approach makes use of Non-Uniform Rational B-splines to represent model geometry and compatible B-splines to approximate the surface current, and adopts the isogeometric concept in which the basis for analysis is taken directly from CAD (geometry) data. The approach allows for high-order approximations and crucially provides a direct link with CAD data structures that allows for efficient design workflows. After outlining the construction of div- and curl-conforming B-splines defined over 3D surfaces we describe their use with the electric and magnetic field integral equations using a Galerkin formulation. We use Bézier extraction to accelerate the computation of NURBS and B-spline terms and employ H-matrices to provide accelerated computations and memory reduction for the dense matrices that result from the boundary integral discretization. The method is verified using the well known Mie scattering problem posed over a perfectly electrically conducting sphere and the classic NASA almond problem. Finally, we demonstrate the ability of the approach to handle models with complex geometry directly from CAD without mesh generation.

Diffuse Scattering from Lead-Containing Ferroelectric Perovskite Oxides

DOE PAGES

Goossens, D. J.

2013-01-01

Ferroelectric materials rely on some type of non-centrosymmetric displacement correlations to give rise to a macroscopic polarisation. These displacements can show short-range order (SRO) that is reflective of the local chemistry, and so studying it reveals important information about how the structure gives rise to the technologically useful properties. A key means of exploring this SRO is diffuse scattering. Conventional structural studies use Bragg peak intensitiesto determine the average structure. In a single crystal diffuse scattering (SCDS) experiment, the coherent scattered intensity is measured at non-integer Miller indices, and can be used to examine the population of local configurations. Thismore » is because the diffuse scattering is sensitive to two-body averages, whereas the Bragg intensity gives single-body averages. This review outlines key results of SCDS studies on several materials and explores the similarities and differences in their diffuse scattering. Random strains are considered, as are models based on a phonon-like picture or a more local-chemistry oriented picture. Limitations of the technique are discussed.« less

Estimating soil matric potential in Owens Valley, California

USGS Publications Warehouse

Sorenson, Stephen K.; Miller, Reuben F.; Welch, Michael R.; Groeneveld, David P.; Branson, Farrel A.

1989-01-01

Much of the floor of Owens Valley, California, is covered with alkaline scrub and alkaline meadow plant communities, whose existence is dependent partly on precipitation and partly on water infiltrated into the rooting zone from the shallow water table. The extent to which these plant communities are capable of adapting to and surviving fluctuations in the water table depends on physiological adaptations of the plants and on the water content, matric potential characteristics of the soils. Two methods were used to estimate soil matric potential in test sites in Owens Valley. The first, the filter-paper method, uses water content of filter papers equilibrated to water content of soil samples taken with a hand auger. The previously published calibration relations used to estimate soil matric potential from the water content of the filter papers were modified on the basis of current laboratory data. The other method of estimating soil matric potential was a modeling approach based on data from this and previous investigations. These data indicate that the base-10 logarithm of soil matric potential is a linear function of gravimetric soil water content for a particular soil. The slope and intercepts of this function vary with the texture and saturation capacity of the soil. Estimates of soil water characteristic curves were made at two sites by averaging the gravimetric soil water content and soil matric potential values from multiple samples at 0.1-m depth intervals derived by using the hand auger and filter-paper method and entering these values in the soil water model. The characteristic curves then were used to estimate soil matric potential from estimates of volumetric soil water content derived from neutron-probe readings. Evaluation of the modeling technique at two study sites indicated that estimates of soil matric potential within 0.5 pF units of the soil matric potential value derived by using the filter-paper method could be obtained 90 to 95 percent of the

N-MODY: A Code for Collisionless N-body Simulations in Modified Newtonian Dynamics

NASA Astrophysics Data System (ADS)

Londrillo, Pasquale; Nipoti, Carlo

2011-02-01

N-MODY is a parallel particle-mesh code for collisionless N-body simulations in modified Newtonian dynamics (MOND). N-MODY is based on a numerical potential solver in spherical coordinates that solves the non-linear MOND field equation, and is ideally suited to simulate isolated stellar systems. N-MODY can be used also to compute the MOND potential of arbitrary static density distributions. A few applications of N-MODY indicate that some astrophysically relevant dynamical processes are profoundly different in MOND and in Newtonian gravity with dark matter.

N-MODY: a code for collisionless N-body simulations in modified Newtonian dynamics.

NASA Astrophysics Data System (ADS)

Londrillo, P.; Nipoti, C.

We describe the numerical code N-MODY, a parallel particle-mesh code for collisionless N-body simulations in modified Newtonian dynamics (MOND). N-MODY is based on a numerical potential solver in spherical coordinates that solves the non-linear MOND field equation, and is ideally suited to simulate isolated stellar systems. N-MODY can be used also to compute the MOND potential of arbitrary static density distributions. A few applications of N-MODY indicate that some astrophysically relevant dynamical processes are profoundly different in MOND and in Newtonian gravity with dark matter.

N-body simulations in modified Newtonian dynamics

NASA Astrophysics Data System (ADS)

Nipoti, C.; Londrillo, P.; Ciotti, L.

We describe some results obtained with N-MODY, a code for N-body simulations of collisionless stellar systems in modified Newtonian dynamics (MOND). We found that a few fundamental dynamical processes are profoundly different in MOND and in Newtonian gravity with dark matter. In particular, violent relaxation, phase mixing and galaxy merging take significantly longer in MOND than in Newtonian gravity, while dynamical friction is more effective in a MOND system than in an equivalent Newtonian system with dark matter.

Intermediate energy proton-deuteron elastic scattering

NASA Technical Reports Server (NTRS)

Wilson, J. W.

1973-01-01

A fully symmetrized multiple scattering series is considered for the description of proton-deuteron elastic scattering. An off-shell continuation of the experimentally known twobody amplitudes that retains the exchange symmeteries required for the calculation is presented. The one boson exchange terms of the two body amplitudes are evaluated exactly in this off-shell prescription. The first two terms of the multiple scattering series are calculated explicitly whereas multiple scattering effects are obtained as minimum variance estimates from the 146-MeV data of Postma and Wilson. The multiple scattering corrections indeed consist of low order partial waves as suggested by Sloan based on model studies with separable interactions. The Hamada-Johnston wave function is shown consistent with the data for internucleon distances greater than about 0.84 fm.

Advanced Progressive Matrices and Sex Differences: Comment to Mackintosh and Bennett (2005)

ERIC Educational Resources Information Center

Colom, Roberto; Abad, Francisco J.

2007-01-01

Mackintosh and Bennett's [Mackintosh, N. J. and Bennett, E. S, (2005). ''What do Raven's Matrices measure? An analysis in terms of sex differences.'' Intelligence 33: 663-674.] study shows that males outperform females in some APM items but not in others, implicating that these items are measuring discriminable mental processes. The present…

Implicit-shifted Symmetric QR Singular Value Decomposition of 3x3 Matrices

DTIC Science & Technology

2016-04-01

Graph 33, 4, 138:1– 138:11. TREFETHEN, L. N., AND BAU III, D. 1997. Numerical linear algebra , vol. 50. Siam. XU, H., SIN, F., ZHU, Y., AND BARBIČ, J...matrices with minimal branching and elementary floating point operations. Tech. rep., University of Wisconsin- Madison. SAITO, S., ZHOU, Z.-Y., AND

CMV matrices in random matrix theory and integrable systems: a survey

NASA Astrophysics Data System (ADS)

Nenciu, Irina

2006-07-01

We present a survey of recent results concerning a remarkable class of unitary matrices, the CMV matrices. We are particularly interested in the role they play in the theory of random matrices and integrable systems. Throughout the paper we also emphasize the analogies and connections to Jacobi matrices.

Quantum Linear System Algorithm for Dense Matrices.

PubMed

Wossnig, Leonard; Zhao, Zhikuan; Prakash, Anupam

2018-02-02

Solving linear systems of equations is a frequently encountered problem in machine learning and optimization. Given a matrix A and a vector b the task is to find the vector x such that Ax=b. We describe a quantum algorithm that achieves a sparsity-independent runtime scaling of O(κ^{2}sqrt[n]polylog(n)/ε) for an n×n dimensional A with bounded spectral norm, where κ denotes the condition number of A, and ε is the desired precision parameter. This amounts to a polynomial improvement over known quantum linear system algorithms when applied to dense matrices, and poses a new state of the art for solving dense linear systems on a quantum computer. Furthermore, an exponential improvement is achievable if the rank of A is polylogarithmic in the matrix dimension. Our algorithm is built upon a singular value estimation subroutine, which makes use of a memory architecture that allows for efficient preparation of quantum states that correspond to the rows of A and the vector of Euclidean norms of the rows of A.

Quantum Linear System Algorithm for Dense Matrices

NASA Astrophysics Data System (ADS)

Wossnig, Leonard; Zhao, Zhikuan; Prakash, Anupam

2018-02-01

Solving linear systems of equations is a frequently encountered problem in machine learning and optimization. Given a matrix A and a vector b the task is to find the vector x such that A x =b . We describe a quantum algorithm that achieves a sparsity-independent runtime scaling of O (κ2√{n }polylog(n )/ɛ ) for an n ×n dimensional A with bounded spectral norm, where κ denotes the condition number of A , and ɛ is the desired precision parameter. This amounts to a polynomial improvement over known quantum linear system algorithms when applied to dense matrices, and poses a new state of the art for solving dense linear systems on a quantum computer. Furthermore, an exponential improvement is achievable if the rank of A is polylogarithmic in the matrix dimension. Our algorithm is built upon a singular value estimation subroutine, which makes use of a memory architecture that allows for efficient preparation of quantum states that correspond to the rows of A and the vector of Euclidean norms of the rows of A .

Multiple scattering in planetary regoliths using first-order incoherent interactions

NASA Astrophysics Data System (ADS)

Muinonen, Karri; Markkanen, Johannes; Väisänen, Timo; Penttilä, Antti

2017-10-01

We consider scattering of light by a planetary regolith modeled using discrete random media of spherical particles. The size of the random medium can range from microscopic sizes of a few wavelengths to macroscopic sizes approaching infinity. The size of the particles is assumed to be of the order of the wavelength. We extend the numerical Monte Carlo method of radiative transfer and coherent backscattering (RT-CB) to the case of dense packing of particles. We adopt the ensemble-averaged first-order incoherent extinction, scattering, and absorption characteristics of a volume element of particles as input for the RT-CB. The volume element must be larger than the wavelength but smaller than the mean free path length of incoherent extinction. In the radiative transfer part, at each absorption and scattering process, we account for absorption with the help of the single-scattering albedo and peel off the Stokes parameters of radiation emerging from the medium in predefined scattering angles. We then generate a new scattering direction using the joint probability density for the local polar and azimuthal scattering angles. In the coherent backscattering part, we utilize amplitude scattering matrices along the radiative-transfer path and the reciprocal path, and utilize the reciprocity of electromagnetic waves to verify the computation. We illustrate the incoherent volume-element scattering characteristics and compare the dense-medium RT-CB to asymptotically exact results computed using the Superposition T-matrix method (STMM). We show that the dense-medium RT-CB compares favorably to the STMM results for the current cases of sparse and dense discrete random media studied. The novel method can be applied in modeling light scattering by the surfaces of asteroids and other airless solar system objects, including UV-Vis-NIR spectroscopy, photometry, polarimetry, and radar scattering problems.Acknowledgments. Research supported by European Research Council with Advanced

Newton-Euler Dynamic Equations of Motion for a Multi-body Spacecraft

NASA Technical Reports Server (NTRS)

Stoneking, Eric

2007-01-01

The Magnetospheric MultiScale (MMS) mission employs a formation of spinning spacecraft with several flexible appendages and thruster-based control. To understand the complex dynamic interaction of thruster actuation, appendage motion, and spin dynamics, each spacecraft is modeled as a tree of rigid bodies connected by spherical or gimballed joints. The method presented facilitates assembling by inspection the exact, nonlinear dynamic equations of motion for a multibody spacecraft suitable for solution by numerical integration. The building block equations are derived by applying Newton's and Euler's equations of motion to an "element" consisting of two bodies and one joint (spherical and gimballed joints are considered separately). Patterns in the "mass" and L'force" matrices guide assembly by inspection of a general N-body tree-topology system. Straightforward linear algebra operations are employed to eliminate extraneous constraint equations, resulting in a minimum-dimension system of equations to solve. This method thus combines a straightforward, easily-extendable, easily-mechanized formulation with an efficient computer implementation.

Low energy peripheral scaling in nucleon-nucleon scattering and uncertainty quantification

NASA Astrophysics Data System (ADS)

Ruiz Simo, I.; Amaro, J. E.; Ruiz Arriola, E.; Navarro Pérez, R.

2018-03-01

We analyze the peripheral structure of the nucleon-nucleon interaction for LAB energies below 350 MeV. To this end we transform the scattering matrix into the impact parameter representation by analyzing the scaled phase shifts (L + 1/2) δ JLS (p) and the scaled mixing parameters (L + 1/2)ɛ JLS (p) in terms of the impact parameter b = (L + 1/2)/p. According to the eikonal approximation, at large angular momentum L these functions should become an universal function of b, independent on L. This allows to discuss in a rather transparent way the role of statistical and systematic uncertainties in the different long range components of the two-body potential. Implications for peripheral waves obtained in chiral perturbation theory interactions to fifth order (N5LO) or from the large body of NN data considered in the SAID partial wave analysis are also drawn from comparing them with other phenomenological high-quality interactions, constructed to fit scattering data as well. We find that both N5LO and SAID peripheral waves disagree more than 5σ with the Granada-2013 statistical analysis, more than 2σ with the 6 statistically equivalent potentials fitting the Granada-2013 database and about 1σ with the historical set of 13 high-quality potentials developed since the 1993 Nijmegen analysis.

Comparison between microwave coherent and incoherent scattering models for wetland vegetation in Poyang Lake area

NASA Astrophysics Data System (ADS)

Xu, Tao; Liao, Jingjuan

2014-11-01

In order to reveal more deeply the scattering characteristics of wetland vegetation and determine the microwave scattering model suitable for the inversion of wetland vegetation parameters, the comparison and analysis between microwave coherent and incoherent scattering models for wetland vegetation in Poyang Lake area were performed in this paper. In the research, we proposed a coherent scattering model exclusive for wetland vegetation, in which, Generalized Rayleigh-Gans (GRG) approach and infinite-length dielectric cylinder were used to calculate single-scattering matrices of wetland vegetation leaves and stalks. In addition, coherent components produced from interaction among the scattering mechanisms and different scatterers were also considered and this coherent model was compared with Michigan Microwave Canopy Scattering (MIMICS) model. The measured data collected in 2011 in Poyang Lake wetland were used as the input parameters of the coherent and incoherent models. We simulated backscattering coefficients of VV, VH and HH polarization at C band and made a comparison between the simulation results and C-band data from the Radarsat-2 satellite. For both coherent and incoherent scattering model, simulation results for HH and VV polarization were better than the simulation results for HV polarization. In addition, comparisons between coherent and incoherent scattering models proved that the coherence triggered by the scattering mechanism and different scatterers can't be ignored. In the research, we analyzed differences between coherent and incoherent scattering models with change of incident angle. In most instances, the difference between coherent and incoherent scattering models is of the order of several dB.

Solution of the determinantal assignment problem using the Grassmann matrices

NASA Astrophysics Data System (ADS)

Karcanias, Nicos; Leventides, John

2016-02-01

The paper provides a direct solution to the determinantal assignment problem (DAP) which unifies all frequency assignment problems of the linear control theory. The current approach is based on the solvability of the exterior equation ? where ? is an n -dimensional vector space over ? which is an integral part of the solution of DAP. New criteria for existence of solution and their computation based on the properties of structured matrices are referred to as Grassmann matrices. The solvability of this exterior equation is referred to as decomposability of ?, and it is in turn characterised by the set of quadratic Plücker relations (QPRs) describing the Grassmann variety of the corresponding projective space. Alternative new tests for decomposability of the multi-vector ? are given in terms of the rank properties of the Grassmann matrix, ? of the vector ?, which is constructed by the coordinates of ?. It is shown that the exterior equation is solvable (? is decomposable), if and only if ? where ?; the solution space for a decomposable ?, is the space ?. This provides an alternative linear algebra characterisation of the decomposability problem and of the Grassmann variety to that defined by the QPRs. Further properties of the Grassmann matrices are explored by defining the Hodge-Grassmann matrix as the dual of the Grassmann matrix. The connections of the Hodge-Grassmann matrix to the solution of exterior equations are examined, and an alternative new characterisation of decomposability is given in terms of the dimension of its image space. The framework based on the Grassmann matrices provides the means for the development of a new computational method for the solutions of the exact DAP (when such solutions exist), as well as computing approximate solutions, when exact solutions do not exist.

Arikan and Alamouti matrices based on fast block-wise inverse Jacket transform

NASA Astrophysics Data System (ADS)

Lee, Moon Ho; Khan, Md Hashem Ali; Kim, Kyeong Jin

2013-12-01

Recently, Lee and Hou (IEEE Signal Process Lett 13: 461-464, 2006) proposed one-dimensional and two-dimensional fast algorithms for block-wise inverse Jacket transforms (BIJTs). Their BIJTs are not real inverse Jacket transforms from mathematical point of view because their inverses do not satisfy the usual condition, i.e., the multiplication of a matrix with its inverse matrix is not equal to the identity matrix. Therefore, we mathematically propose a fast block-wise inverse Jacket transform of orders N = 2 k , 3 k , 5 k , and 6 k , where k is a positive integer. Based on the Kronecker product of the successive lower order Jacket matrices and the basis matrix, the fast algorithms for realizing these transforms are obtained. Due to the simple inverse and fast algorithms of Arikan polar binary and Alamouti multiple-input multiple-output (MIMO) non-binary matrices, which are obtained from BIJTs, they can be applied in areas such as 3GPP physical layer for ultra mobile broadband permutation matrices design, first-order q-ary Reed-Muller code design, diagonal channel design, diagonal subchannel decompose for interference alignment, and 4G MIMO long-term evolution Alamouti precoding design.

Introduction to the QIAT Self-Evaluation Matrices

ERIC Educational Resources Information Center

Zabala, Joy Smiley; Carl, Diana F.

2004-01-01

The QIAT Self-Evaluation Matrices (QILT, 2001) were developed in response to formative evaluation data indicating a need for a model that could assist in the application of the Quality Indicators for Assistive Technology Services in Schools (Zabala, et al, 2000). The QIAT Matrices are based on the idea that change does not happen immediately, but…

"G.P.S Matrices" programme: A method to improve the mastery level of social science students in matrices operations

NASA Astrophysics Data System (ADS)

Lee, Ken Voon

2013-04-01

The purpose of this action research was to increase the mastery level of Form Five Social Science students in Tawau II National Secondary School in the operations of addition, subtraction and multiplication of matrices in Mathematics. A total of 30 students were involved. Preliminary findings through the analysis of pre-test results and questionnaire had identified the main problem faced in which the students felt confused with the application of principles of the operations of matrices when performing these operations. Therefore, an action research was conducted using an intervention programme called "G.P.S Matrices" to overcome the problem. This programme was divided into three phases. 'Gift of Matrices' phase aimed at forming matrix teaching aids. The second and third phases were 'Positioning the Elements of Matrices' and 'Strenghtening the Concept of Matrices'. These two phases were aimed at increasing the level of understanding and memory of the students towards the principles of matrix operations. Besides, this third phase was also aimed at creating an interesting learning environment. A comparison between the results of pre-test and post-test had shown a remarkable improvement in students' performances after implementing the programme. In addition, the analysis of interview findings also indicated a positive feedback on the changes in students' attitude, particularly in the aspect of students' understanding level. Moreover, the level of students' memory also increased following the use of the concrete matrix teaching aids created in phase one. Besides, teachers felt encouraging when conducive learning environment was created through students' presentation activity held in third phase. Furthermore, students were voluntarily involved in these student-centred activities. In conclusion, this research findings showed an increase in the mastery level of students in these three matrix operations and thus the objective of the research had been achieved.

Action-minimizing solutions of the one-dimensional N-body problem

NASA Astrophysics Data System (ADS)

Yu, Xiang; Zhang, Shiqing

2018-05-01

We supplement the following result of C. Marchal on the Newtonian N-body problem: A path minimizing the Lagrangian action functional between two given configurations is always a true (collision-free) solution when the dimension d of the physical space R^d satisfies d≥2. The focus of this paper is on the fixed-ends problem for the one-dimensional Newtonian N-body problem. We prove that a path minimizing the action functional in the set of paths joining two given configurations and having all the time the same order is always a true (collision-free) solution. Considering the one-dimensional N-body problem with equal masses, we prove that (i) collision instants are isolated for a path minimizing the action functional between two given configurations, (ii) if the particles at two endpoints have the same order, then the path minimizing the action functional is always a true (collision-free) solution and (iii) when the particles at two endpoints have different order, although there must be collisions for any path, we can prove that there are at most N! - 1 collisions for any action-minimizing path.

Astrophysical N-body Simulations Using Hierarchical Tree Data Structures

NASA Astrophysics Data System (ADS)

Warren, M. S.; Salmon, J. K.

The authors report on recent large astrophysical N-body simulations executed on the Intel Touchstone Delta system. They review the astrophysical motivation and the numerical techniques and discuss steps taken to parallelize these simulations. The methods scale as O(N log N), for large values of N, and also scale linearly with the number of processors. The performance sustained for a duration of 67 h, was between 5.1 and 5.4 Gflop/s on a 512-processor system.

Enhanced light scattering of the forbidden longitudinal optical phonon mode studied by micro-Raman spectroscopy on single InN nanowires.

PubMed

Schäfer-Nolte, E O; Stoica, T; Gotschke, T; Limbach, F A; Sutter, E; Sutter, P; Grützmacher, D; Calarco, R

2010-08-06

In the literature, there are controversies on the interpretation of the appearance in InN Raman spectra of a strong scattering peak in the energy region of the unscreened longitudinal optical (LO) phonons, although a shift caused by the phonon-plasmon interaction is expected for the high conductance observed in this material. Most measurements on light scattering are performed on ensembles of InN nanowires (NWs). However, it is important to investigate the behavior of individual nanowires and here we report on micro-Raman measurements on single nanowires. When changing the polarization direction of the incident light from parallel to perpendicular to the wire, the expected reduction of the Raman scattering was observed for transversal optical (TO) and E(2) phonon scattering modes, while a strong symmetry-forbidden LO mode was observed independently on the laser polarization direction. Single Mg- and Si-doped crystalline InN nanowires were also investigated. Magnesium doping results in a sharpening of the Raman peaks, while silicon doping leads to an asymmetric broadening of the LO peak. The results can be explained based on the influence of the high electron concentration with a strong contribution of the surface accumulation layer and the associated internal electric field.

The quantum n-body problem in dimension d ⩾ n – 1: ground state

NASA Astrophysics Data System (ADS)

Miller, Willard, Jr.; Turbiner, Alexander V.; Escobar-Ruiz, M. A.

2018-05-01

We employ generalized Euler coordinates for the n body system in dimensional space, which consists of the centre-of-mass vector, relative (mutual) mass-independent distances r ij and angles as remaining coordinates. We prove that the kinetic energy of the quantum n-body problem for can be written as the sum of three terms: (i) kinetic energy of centre-of-mass, (ii) the second order differential operator which depends on relative distances alone and (iii) the differential operator which annihilates any angle-independent function. The operator has a large reflection symmetry group and in variables is an algebraic operator, which can be written in terms of generators of the hidden algebra . Thus, makes sense of the Hamiltonian of a quantum Euler–Arnold top in a constant magnetic field. It is conjectured that for any n, the similarity-transformed is the Laplace–Beltrami operator plus (effective) potential; thus, it describes a -dimensional quantum particle in curved space. This was verified for . After de-quantization the similarity-transformed becomes the Hamiltonian of the classical top with variable tensor of inertia in an external potential. This approach allows a reduction of the dn-dimensional spectral problem to a -dimensional spectral problem if the eigenfunctions depend only on relative distances. We prove that the ground state function of the n body problem depends on relative distances alone.

Tholins as Coloring Agents on Outer Solar System Bodies

NASA Technical Reports Server (NTRS)

Cruikshank, Dale P.; Imanaka, Hiroshi; DalleOre, Cristina M.

2005-01-01

The red colors of many solid bodies in outer Solar System may be caused by tholins, which are refractory organic complexes, incorporated in their surface materials. Tholins synthesized in the laboratory are shown to match the colors of these bodies when their optical properties are used in rigorous scattering models. We review recent successes in modeling the spectra of icy outer Solar System bodies with tholins as the coloring agents. New work on the systematic laboratory synthesis and analysis of tholins made by cold plasma discharge in mixtures of gaseous CH4/N2 shows that the composition of the tholin depends strongly on the pressure in the reaction chamber, and only weakly on the mixing fraction of CH4 relative to N2. In tholins made at high pressure (e.g., 23 hPa) the abundance of aliphatic hydrocarbons is greater and the abundance of aromatic hydrocarbons is less than in tholins made at low pressure (e.g., 0.13 hPa). Tholins made at low deposition pressures show a greater abundance of N-H bonds.

Efficient propagation-inside-layer expansion algorithm for solving the scattering from three-dimensional nested homogeneous dielectric bodies with arbitrary shape.

PubMed

Bellez, Sami; Bourlier, Christophe; Kubické, Gildas

2015-03-01

This paper deals with the evaluation of electromagnetic scattering from a three-dimensional structure consisting of two nested homogeneous dielectric bodies with arbitrary shape. The scattering problem is formulated in terms of a set of Poggio-Miller-Chang-Harrington-Wu integral equations that are afterwards converted into a system of linear equations (impedance matrix equation) by applying the Galerkin method of moments (MoM) with Rao-Wilton-Glisson basis functions. The MoM matrix equation is then solved by deploying the iterative propagation-inside-layer expansion (PILE) method in order to obtain the unknown surface current densities, which are thereafter used to handle the radar cross-section (RCS) patterns. Some numerical results for various structures including canonical geometries are presented and compared with those of the FEKO software in order to validate the PILE-based approach as well as to show its efficiency to analyze the full-polarized RCS patterns.

Rapid Quantification of N-Methyl-2-pyrrolidone in Polymer Matrices by Thermal Desorption-GC/MS.

PubMed

Kim, Young-Min; Kim, Jae Woo; Moon, Hye Mi; Lee, Min-Jin; Hosaka, Akihiko; Watanabe, Atsushi; Teramae, Norio; Park, Young-Kwon; Myung, Seung-Woon

2017-01-01

Analysis of a residual solvent in polymeric materials has become an important issue due to the increased regulations and standards for its use. N-Methyl-2-pyrrolidone (NMP) is a solvent widely used in many industries and restricted as one of the chemicals under EU REACH regulations due to its potential harmful effects. In this study, thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) is applied for the quantitative analysis of NMP with the use of a polymer-coated sample cup. By using the polymer-coated sample cup, the vaporization of NMP was prevented during waiting time before TD-GC/MS analysis. The calibration curve for the TD method showed good linearity (correlation coefficient, r 2 = 0.9998) and precision values (below 5.3% RSD). NMP recovery rates in different polymer matrices (PS, PMMA and PVC) were in the range of 98.8 to 106.6% with RSD values below 5.0%. The quantification result (600 mg NMP/kg PVC) for the blind NMP carrying sample in a PVC matrix by TD-GC/MS was higher than that (532 mg NMP/kg PVC) by solvent extraction-GC/MS method.

Structure-performance relationships of phenyl cinnamic acid derivatives as MALDI-MS matrices for sulfatide detection.

PubMed

Tambe, Suparna; Blott, Henning; Fülöp, Annabelle; Spang, Nils; Flottmann, Dirk; Bräse, Stefan; Hopf, Carsten; Junker, Hans-Dieter

2017-02-01

A key aspect for the further development of matrix-assisted laser desorption ionization (MALDI)-mass spectrometry (MS) is a better understanding of the working principles of MALDI matrices. To address this issue, a chemical compound library of 59 structurally related cinnamic acid derivatives was synthesized. Potential MALDI matrices were evaluated with sulfatides, a class of anionic lipids which are abundant in complex brain lipid mixtures. For each matrix relative mean S/N ratios of sulfatides were determined against 9-aminoacridine as a reference matrix using negative ion mass spectrometry with 355 and 337 nm laser systems. The comparison of matrix features with their corresponding relative mean S/N ratios for sulfatide detection identified correlations between matrix substitution patterns, their chemical functionality, and their MALDI-MS performance. Crystal structures of six selected matrices provided structural insight in hydrogen bond interactions in the solid state. Principal component analysis allowed the additional identification of correlation trends between structural and physical matrix properties like number of exchangeable protons at the head group, MW, logP, UV-Vis, and sulfatide detection sensitivity. Graphical abstract Design, synthesis and mass spectrometric evaluation of MALDI-MS matrix compound libraries allows the identification of matrix structure - MALDI-MS performance relationships using multivariate statistics as a tool.

Relativistic N-body simulations with massive neutrinos

NASA Astrophysics Data System (ADS)

Adamek, Julian; Durrer, Ruth; Kunz, Martin

2017-11-01

Some of the dark matter in the Universe is made up of massive neutrinos. Their impact on the formation of large scale structure can be used to determine their absolute mass scale from cosmology, but to this end accurate numerical simulations have to be developed. Due to their relativistic nature, neutrinos pose additional challenges when one tries to include them in N-body simulations that are traditionally based on Newtonian physics. Here we present the first numerical study of massive neutrinos that uses a fully relativistic approach. Our N-body code, gevolution, is based on a weak-field formulation of general relativity that naturally provides a self-consistent framework for relativistic particle species. This allows us to model neutrinos from first principles, without invoking any ad-hoc recipes. Our simulation suite comprises some of the largest neutrino simulations performed to date. We study the effect of massive neutrinos on the nonlinear power spectra and the halo mass function, focusing on the interesting mass range between 0.06 eV and 0.3 eV and including a case for an inverted mass hierarchy.

Occurrence and quantification of Shiga toxin-producing Escherichia coli from food matrices

PubMed Central

Sethulekshmi, C.; Latha, C.; Anu, C. J.

2018-01-01

Aim: The objective of the study was to detect Shiga toxin-producing Escherichia coli (STEC) and develop a quantitative polymerase chain reaction (qPCR) assay to quantify the bacterial DNA present in different food matrices. Materials and Methods: A total of 758 samples were collected during a period from January 2015 to December 2016 from Kozhikode, Thrissur, and Alappuzha districts of Kerala. The samples consisted of raw milk (135), pasteurized milk (100), beef (132), buffalo meat (130), chevon (104), beef kheema (115), and beef sausage (42). All the samples collected were subjected to isolation and identification of STEC by conventional culture technique. Confirmation of virulence genes was carried out using PCR. For the quantification of STEC in different food matrices, a qPCR was standardized against stx1 gene of STEC by the construction of standard curve using SYBR green chemistry. Results: The overall occurrence of STEC in raw milk (n=135), beef (n=132), buffalo meat (n=130), chevon (n=104), and beef kheema (n=115) samples collected from Kozhikode, Thrissur, and Alappuzha districts of Kerala was 19.26%, 41.6%, 16.92%, 28.85%, and 41.74%, respectively. PCR revealed the presence of stx 1 and stx 2 genes in 88.46 and 83.64 and 30.77 and 40.00% of STEC isolates from raw milk and beef samples, respectively, while 100% of the STEC isolates from buffalo beef and beef kheema samples carried stx 1 gene. Real-time qPCR assay was used to quantify the bacterial cells present in different food matrices. The standard curve was developed, and the slopes, intercept, and R2 of linear regression curves were −3.10, 34.24, and 0.99, respectively. Conclusion: The considerably high occurrence of STEC in the study confirms the importance of foods of animal origin as a vehicle of infection to humans. In the present study, on comparing the overall occurrence of STEC, the highest percentage of occurrence was reported in beef kheema samples. The study shows the need for rigid food

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

Flow Simulation of N3-X Hybrid Wing-Body Configuration

NASA Technical Reports Server (NTRS)

Kim, Hyoungjin; Liou, Meng-Sing

2013-01-01

System studies show that a N3-X hybrid wing-body aircraft with a turboelectric distributed propulsion system using a mail-slot inlet/nozzle nacelle can meet the environmental and performance goals for N+3 generation transports (three generations beyond the current air transport technology level) set by NASA s Subsonic Fixed Wing Project. In this study, a Navier-Stokes flow simulation of N3-X on hybrid unstructured meshes was conducted, including the mail-slot propulsor. The geometry of the mail-slot propulsor was generated by a CAD (Computer-Aided Design)-free shape parameterization. A body force approach was used for a more realistic and efficient simulation of the turning and loss effects of the fan blades and the inlet-fan interactions. Flow simulation results of the N3-X demonstrates the validity of the present approach.

M-matrices with prescribed elementary divisors

NASA Astrophysics Data System (ADS)

Soto, Ricardo L.; Díaz, Roberto C.; Salas, Mario; Rojo, Oscar

2017-09-01

A real matrix A is said to be an M-matrix if it is of the form A=α I-B, where B is a nonnegative matrix with Perron eigenvalue ρ (B), and α ≥slant ρ (B) . This paper provides sufficient conditions for the existence and construction of an M-matrix A with prescribed elementary divisors, which are the characteristic polynomials of the Jordan blocks of the Jordan canonical form of A. This inverse problem on M-matrices has not been treated until now. We solve the inverse elementary divisors problem for diagonalizable M-matrices and the symmetric generalized doubly stochastic inverse M-matrix problem for lists of real numbers and for lists of complex numbers of the form Λ =\\{λ 1, a+/- bi, \\ldots, a+/- bi\\} . The constructive nature of our results allows for the computation of a solution matrix. The paper also discusses an application of M-matrices to a capacity problem in wireless communications.

Laser Light Scattering by Shock Waves

NASA Technical Reports Server (NTRS)

Panda, J.; Adamovsky, G.

1995-01-01

Scattering of coherent light as it propagates parallel to a shock wave, formed in front of a bluff cylindrical body placed in a supersonic stream, is studied experimentally and numerically. Two incident optical fields are considered. First, a large diameter collimated beam is allowed to pass through the shock containing flow. The light intensity distribution in the resultant shadowgraph image, measured by a low light CCD camera, shows well-defined fringes upstream and downstream of the shadow cast by the shock. In the second situation, a narrow laser beam is brought to a grazing incidence on the shock and the scattered light, which appears as a diverging sheet from the point of interaction, is visualized and measured on a screen placed normal to the laser path. Experiments are conducted on shocks formed at various free-stream Mach numbers, M, and total pressures, P(sub 0). It is found that the widths of the shock shadows in a shadowgraph image become independent of M and P(sub 0) when plotted against the jump in the refractive index, (Delta)n, created across the shock. The total scattered light measured from the narrow laser beam and shock interaction also follows the same trend. In the numerical part of the study, the shock is assumed to be a 'phase object', which introduces phase difference between the upstream and downstream propagating parts of the light disturbances. For a given shape and (Delta)n of the bow shock the phase and amplitude modulations are first calculated by ray tracing. The wave front is then propagated to the screen using the Fresnet diffraction equation. The calculated intensity distribution, for both of the incident optical fields, shows good agreement with the experimental data.

Body Temperature Controlled Optical and Thermal Information Storage Light Scattering Display with Fluorescence Effect and High Mechanical Strength.

PubMed

Chen, Si; Tong, Xiaoqian; He, Huiwen; Ma, Meng; Shi, Yanqin; Wang, Xu

2017-04-05

A kind of body temperature controlled optical and thermal information storage light scattering display based on super strong liquid crystalline physical gel with special "loofah-like gel network" was successfully prepared. Such liquid crystal (LC) gel was obtained by mixing a dendritic gelator (POSS-G1-BOC), an azobenzene compound (2Azo2), and a phosphor tethered liquid crystalline host (5CB), which could show its best contrast ratio at around human body temperature under UV light because of the phosphor's fluorescence effect. The gel also has quite strong mechanical strength, which could be used in wearable device field especially under sunlight, even under the forcing conditions as harsh as being centrifuged for 10 min at the speed of 2000 r/min. The whole production process of such a display is quite simple and could lead to displays at any size through noncontact writing. We believe it will have wide applications in the future.

Analytical Applications Of High-Resolution Molecular Fluorescence Spectroscopy In Low Temperature Solid Matrices

NASA Astrophysics Data System (ADS)

Hofstraat, Johannes W.; van Zeijl, W. J.; Smedes, F.; Ariese, Freek; Gooijer, Cees; Velthorst, Nel H.; Locher, R.; Renn, Alois; Wild, Urs P.

1989-05-01

High-resolution fluorescence spectroscopy may be used to obtain highly specific, vibrationally resolved spectral signatures of molecules. Two techniques are presented that both make use of low temperature, solid matrices. In Shpol'skii spectroscopy highly resolved spectra are obtained by employing n-alkanes as solvents that form neat crystalline matrices at low temperatures in which the guest molecules occupy well defined substitutional sites. Fluorescence line-narrowing spectroscopy is based on the application of selective (mostly laser-) excitation of the guest molecules. Principles and analytical applications of both techniques will be discussed. Specific attention will be paid to the determination of pyrene in bird meat by means of Shpol'skii spectroscopy and to the possibilities of applying two-dimensional fluorescence line-narrowing spectroscopy.

Quantitative fluorescence and elastic scattering tissue polarimetry using an Eigenvalue calibrated spectroscopic Mueller matrix system.

PubMed

Soni, Jalpa; Purwar, Harsh; Lakhotia, Harshit; Chandel, Shubham; Banerjee, Chitram; Kumar, Uday; Ghosh, Nirmalya

2013-07-01

A novel spectroscopic Mueller matrix system has been developed and explored for both fluorescence and elastic scattering polarimetric measurements from biological tissues. The 4 × 4 Mueller matrix measurement strategy is based on sixteen spectrally resolved (λ = 400 - 800 nm) measurements performed by sequentially generating and analyzing four elliptical polarization states. Eigenvalue calibration of the system ensured high accuracy of Mueller matrix measurement over a broad wavelength range, either for forward or backscattering geometry. The system was explored for quantitative fluorescence and elastic scattering spectroscopic polarimetric studies on normal and precancerous tissue sections from human uterine cervix. The fluorescence spectroscopic Mueller matrices yielded an interesting diattenuation parameter, exhibiting differences between normal and precancerous tissues.

Influence of Surface Passivation on AlN Barrier Stress and Scattering Mechanism in Ultra-thin AlN/GaN Heterostructure Field-Effect Transistors.

PubMed

Lv, Y J; Song, X B; Wang, Y G; Fang, Y L; Feng, Z H

2016-12-01

Ultra-thin AlN/GaN heterostructure field-effect transistors (HFETs) with, and without, SiN passivation were fabricated by the same growth and device processes. Based on the measured DC characteristics, including the capacitance-voltage (C-V) and output current-voltage (I-V) curves, the variation of electron mobility with gate bias was found to be quite different for devices with, and without, SiN passivation. Although the AlN barrier layer is ultra thin (c. 3 nm), it was proved that SiN passivation induces no additional tensile stress and has no significant influence on the piezoelectric polarization of the AlN layer using Hall and Raman measurements. The SiN passivation was found to affect the surface properties, thereby increasing the electron density of the two-dimensional electron gas (2DEG) under the access region. The higher electron density in the access region after SiN passivation enhanced the electrostatic screening for the non-uniform distributed polarization charges, meaning that the polarization Coulomb field scattering has a weaker effect on the electron drift mobility in AlN/GaN-based devices.

Fast Multipole Methods for Three-Dimensional N-body Problems

NASA Technical Reports Server (NTRS)

Koumoutsakos, P.

1995-01-01

We are developing computational tools for the simulations of three-dimensional flows past bodies undergoing arbitrary motions. High resolution viscous vortex methods have been developed that allow for extended simulations of two-dimensional configurations such as vortex generators. Our objective is to extend this methodology to three dimensions and develop a robust computational scheme for the simulation of such flows. A fundamental issue in the use of vortex methods is the ability of employing efficiently large numbers of computational elements to resolve the large range of scales that exist in complex flows. The traditional cost of the method scales as Omicron (N(sup 2)) as the N computational elements/particles induce velocities at each other, making the method unacceptable for simulations involving more than a few tens of thousands of particles. In the last decade fast methods have been developed that have operation counts of Omicron (N log N) or Omicron (N) (referred to as BH and GR respectively) depending on the details of the algorithm. These methods are based on the observation that the effect of a cluster of particles at a certain distance may be approximated by a finite series expansion. In order to exploit this observation we need to decompose the element population spatially into clusters of particles and build a hierarchy of clusters (a tree data structure) - smaller neighboring clusters combine to form a cluster of the next size up in the hierarchy and so on. This hierarchy of clusters allows one to determine efficiently when the approximation is valid. This algorithm is an N-body solver that appears in many fields of engineering and science. Some examples of its diverse use are in astrophysics, molecular dynamics, micro-magnetics, boundary element simulations of electromagnetic problems, and computer animation. More recently these N-body solvers have been implemented and applied in simulations involving vortex methods. Koumoutsakos and Leonard (1995

Hierarchical Galaxy Growth and Scatter in the Stellar Mass-Halo Mass Relation

NASA Astrophysics Data System (ADS)

Gu, Meng; Conroy, Charlie; Behroozi, Peter

2016-12-01

The relation between galaxies and dark matter halos reflects the combined effects of many distinct physical processes. Observations indicate that the z = 0 stellar mass-halo mass (SMHM) relation has remarkably small scatter in stellar mass at fixed halo mass (≲0.2 dex), with little dependence on halo mass. We investigate the origins of this scatter by combining N-body simulations with observational constraints on the SMHM relation. We find that at the group and cluster scale ({M}{vir}\\gt {10}14 {M}⊙ ) the scatter due purely to hierarchical assembly is ≈ 0.16 dex, which is comparable to recent direct observational estimates. At lower masses, mass buildup since z≈ 2 is driven largely by in situ growth. We include a model for the in situ buildup of stellar mass and find that an intrinsic scatter in this growth channel of 0.2 dex produces a relation between scatter and halo mass that is consistent with observations from {10}12 {M}⊙ \\lt {M}{vir}\\lt {10}14.75 {M}⊙ . The approximately constant scatter across a wide range of halo masses at z = 0 thus appears to be a coincidence, as it is determined largely by in situ growth at low masses and by hierarchical assembly at high masses. These results indicate that the scatter in the SMHM relation can provide unique insight into the regularity of the galaxy formation process.

The Modern Origin of Matrices and Their Applications

ERIC Educational Resources Information Center

Debnath, L.

2014-01-01

This paper deals with the modern development of matrices, linear transformations, quadratic forms and their applications to geometry and mechanics, eigenvalues, eigenvectors and characteristic equations with applications. Included are the representations of real and complex numbers, and quaternions by matrices, and isomorphism in order to show…

Flux Jacobian Matrices For Equilibrium Real Gases

NASA Technical Reports Server (NTRS)

Vinokur, Marcel

1990-01-01

Improved formulation includes generalized Roe average and extension to three dimensions. Flux Jacobian matrices derived for use in numerical solutions of conservation-law differential equations of inviscid flows of ideal gases extended to real gases. Real-gas formulation of these matrices retains simplifying assumptions of thermodynamic and chemical equilibrium, but adds effects of vibrational excitation, dissociation, and ionization of gas molecules via general equation of state.

Controlled growth factor release from synthetic extracellular matrices

NASA Astrophysics Data System (ADS)

Lee, Kuen Yong; Peters, Martin C.; Anderson, Kenneth W.; Mooney, David J.

2000-12-01

Polymeric matrices can be used to grow new tissues and organs, and the delivery of growth factors from these matrices is one method to regenerate tissues. A problem with engineering tissues that exist in a mechanically dynamic environment, such as bone, muscle and blood vessels, is that most drug delivery systems have been designed to operate under static conditions. We thought that polymeric matrices, which release growth factors in response to mechanical signals, might provide a new approach to guide tissue formation in mechanically stressed environments. Critical design features for this type of system include the ability to undergo repeated deformation, and a reversible binding of the protein growth factors to polymeric matrices to allow for responses to repeated stimuli. Here we report a model delivery system that can respond to mechanical signalling and upregulate the release of a growth factor to promote blood vessel formation. This approach may find a number of applications, including regeneration and engineering of new tissues and more general drug-delivery applications.

Matrices. New Topics for Secondary School Mathematics: Materials and Software.

ERIC Educational Resources Information Center

North Carolina School of Science and Mathematics. Dept. of Mathematics and Computer Science.

This material on matrices is part of "Introduction to College Mathematics" (ICM), designed to prepare high school students who have students who have completed algebra II for the variety of mathematics they will encounter in college and beyond. The concept goals of this unit are to use matrices to model real-world phenomena, to use matrices as…

Interrelating meteorite and asteroid spectra at UV-Vis-NIR wavelengths using novel multiple-scattering methods

NASA Astrophysics Data System (ADS)

Martikainen, Julia; Penttilä, Antti; Gritsevich, Maria; Muinonen, Karri

2017-10-01

Asteroids have remained mostly the same for the past 4.5 billion years, and provide us information on the origin, evolution and current state of the Solar System. Asteroids and meteorites can be linked by matching their respective reflectance spectra. This is difficult, because spectral features depend strongly on the surface properties, and meteorite surfaces are free of regolith dust present in asteroids. Furthermore, asteroid surfaces experience space weathering which affects their spectral features.We present a novel simulation framework for assessing the spectral properties of meteorites and asteroids and matching their reflectance spectra. The simulations are carried out by utilizing a light-scattering code that takes inhomogeneous waves into account and simulates light scattering by Gaussian-random-sphere particles large compared to the wavelength of the incident light. The code uses incoherent input and computes phase matrices by utilizing incoherent scattering matrices. Reflectance spectra are modeled by combining olivine, pyroxene, and iron, the most common materials that dominate the spectral features of asteroids and meteorites. Space weathering is taken into account by adding nanoiron into the modeled asteroid spectrum. The complex refractive indices needed for the simulations are obtained from existing databases, or derived using an optimization that utilizes our ray-optics code and the measured spectrum of the material.We demonstrate our approach by applying it to the reflectance spectrum of (4) Vesta and the reflectance spectrum of the Johnstown meteorite measured with the University of Helsinki integrating-sphere UV-Vis-NIR spectrometer.Acknowledgments. The research is funded by the ERC Advanced Grant No. 320773 (SAEMPL).

Fluctuating volume-current formulation of electromagnetic fluctuations in inhomogeneous media: Incandescence and luminescence in arbitrary geometries

NASA Astrophysics Data System (ADS)

Polimeridis, Athanasios G.; Reid, M. T. H.; Jin, Weiliang; Johnson, Steven G.; White, Jacob K.; Rodriguez, Alejandro W.

2015-10-01

We describe a fluctuating volume-current formulation of electromagnetic fluctuations that extends our recent work on heat exchange and Casimir interactions between arbitrarily shaped homogeneous bodies [A. W. Rodriguez, M. T. H. Reid, and S. G. Johnson, Phys. Rev. B 88, 054305 (2013), 10.1103/PhysRevB.88.054305] to situations involving incandescence and luminescence problems, including thermal radiation, heat transfer, Casimir forces, spontaneous emission, fluorescence, and Raman scattering, in inhomogeneous media. Unlike previous scattering formulations based on field and/or surface unknowns, our work exploits powerful techniques from the volume-integral equation (VIE) method, in which electromagnetic scattering is described in terms of volumetric, current unknowns throughout the bodies. The resulting trace formulas (boxed equations) involve products of well-studied VIE matrices and describe power and momentum transfer between objects with spatially varying material properties and fluctuation characteristics. We demonstrate that thanks to the low-rank properties of the associated matrices, these formulas are susceptible to fast-trace computations based on iterative methods, making practical calculations tractable. We apply our techniques to study thermal radiation, heat transfer, and fluorescence in complicated geometries, checking our method against established techniques best suited for homogeneous bodies as well as applying it to obtain predictions of radiation from complex bodies with spatially varying permittivities and/or temperature profiles.

Unchained polygons and the N-body problem

NASA Astrophysics Data System (ADS)

Chenciner, A.; Féjoz, J.

2009-02-01

We study both theoretically and numerically the Lyapunov families which bifurcate in the vertical direction from a horizontal relative equilibrium in ℝ3. As explained in [1], very symmetric relative equilibria thus give rise to some recently studied classes of periodic solutions. We discuss the possibility of continuing these families globally as action minimizers in a rotating frame where they become periodic solutions with particular symmetries. A first step is to give estimates on intervals of the frame rotation frequency over which the relative equilibrium is the sole absolute action minimizer: this is done by generalizing to an arbitrary relative equilibrium the method used in [2] by V. Batutello and S. Terracini. In the second part, we focus on the relative equilibrium of the equal-mass regular N-gon. The proof of the local existence of the vertical Lyapunov families relies on the fact that the restriction to the corresponding directions of the quadratic part of the energy is positive definite. We compute the symmetry groups G r/s ( N, k, η) of the vertical Lyapunov families observed in appropriate rotating frames, and use them for continuing the families globally. The paradigmatic examples are the “Eight” families for an odd number of bodies and the “Hip- Hop” families for an even number. The first ones generalize Marchal’s P 12 family for 3 bodies, which starts with the equilateral triangle and ends with the Eight [1, 3-6]; the second ones generalize the Hip-Hop family for 4 bodies, which starts from the square and ends with the Hip-Hop [1, 7, 8]. We argue that it is precisely for these two families that global minimization may be used. In the other cases, obstructions to the method come from isomorphisms between the symmetries of different families; this is the case for the so-called “chain” choreographies (see [6]), where only a local minimization property is true (except for N = 3). Another interesting feature of these chains is the

Almost commuting self-adjoint matrices: The real and self-dual cases

NASA Astrophysics Data System (ADS)

Loring, Terry A.; Sørensen, Adam P. W.

2016-08-01

We show that a pair of almost commuting self-adjoint, symmetric matrices is close to a pair of commuting self-adjoint, symmetric matrices (in a uniform way). Moreover, we prove that the same holds with self-dual in place of symmetric and also for paths of self-adjoint matrices. Since a symmetric, self-adjoint matrix is real, we get a real version of Huaxin Lin’s famous theorem on almost commuting matrices. Similarly, the self-dual case gives a version for matrices over the quaternions. To prove these results, we develop a theory of semiprojectivity for real C*-algebras and also examine various definitions of low-rank for real C*-algebras.

Ab initio many-body calculations of nucleon- 4He scattering with three-nucleon forces

DOE PAGES

Hupin, Guillaume; Langhammer, Joachim; Navratil, Petr; ...

2013-11-27

We extend the ab initio no-core shell model/resonating-group method to include three-nucleon (3N) interactions for the description of nucleon-nucleus collisions. We outline the formalism, give algebraic expressions for the 3N-force integration kernels, and discuss computational aspects of two alternative implementations. The extended theoretical framework is then applied to nucleon- 4He elastic scattering using similarity-renormalization-group (SRG)-evolved nucleon-nucleon plus 3N potentials derived from chiral effective field theory. We analyze the convergence properties of the calculated phase shifts and explore their dependence upon the SRG evolution parameter. We include up to six excited states of the 4He target and find significant effects frommore » the inclusion of the chiral 3N force, e.g., it enhances the spin-orbit splitting between the 3/2 – and 1/2 – resonances and leads to an improved agreement with the phase shifts obtained from an accurate R-matrix analysis of the five-nucleon experimental data. As a result, we find remarkably good agreement with measured differential cross sections at various energies below the d+ 3H threshold, while analyzing powers manifest larger deviations from experiment for certain energies and angles.« less

Fidelity decay of the two-level bosonic embedded ensembles of random matrices

NASA Astrophysics Data System (ADS)

Benet, Luis; Hernández-Quiroz, Saúl; Seligman, Thomas H.

2010-12-01

We study the fidelity decay of the k-body embedded ensembles of random matrices for bosons distributed over two single-particle states. Fidelity is defined in terms of a reference Hamiltonian, which is a purely diagonal matrix consisting of a fixed one-body term and includes the diagonal of the perturbing k-body embedded ensemble matrix, and the perturbed Hamiltonian which includes the residual off-diagonal elements of the k-body interaction. This choice mimics the typical mean-field basis used in many calculations. We study separately the cases k = 2 and 3. We compute the ensemble-averaged fidelity decay as well as the fidelity of typical members with respect to an initial random state. Average fidelity displays a revival at the Heisenberg time, t = tH = 1, and a freeze in the fidelity decay, during which periodic revivals of period tH are observed. We obtain the relevant scaling properties with respect to the number of bosons and the strength of the perturbation. For certain members of the ensemble, we find that the period of the revivals during the freeze of fidelity occurs at fractional times of tH. These fractional periodic revivals are related to the dominance of specific k-body terms in the perturbation.

[Analysis of Scattered Radiation in an Irradiated Body by Means of the Monte Carlo Simulation: Variation of the Subjective Contrast Due to Difference in the Location of Inhomogeneous Region].

PubMed

Kato, Hideki; Sawada, Michito

2015-12-01

When an inhomogeneous medium such as bone, whose composition or density are clearly different from that of soft tissue of human body, exist in irradiated body, a subjective contrast of X-ray image changes by the location of these inhomogeneous medium. This cause due to the change of behavior of scattered photons in the body depends on the location of inhomogeneous medium besides due to the influence of a penumbra. But this mechanism is not explained clearly yet. In this paper, it was analyzed by means of the Monte Carlo simulation that what kind of difference occurs to a subjective contrast by the difference in location of inhomogeneous medium in water phantom and that a change in behavior of scattered photons in the phantom influences a subjective contrast by what kind of mechanism. In this case the inhomogeneous medium is bone, whose effective atomic number and density are higher than that of water, the subjective contrast of X-ray image degrades when bone is located near the entrance surface (upper position) than located near the exit surface (lower position). This is caused by the number of scattered photons, originated in primary photons incident upon the zone besides the region from entrance surface to exit surface including inhomogeneous medium and incident on the area of shadow of inhomogeneous medium on the image detector, is greater in case of the upper position than in case of the lower position. In the lower position, many of these scattered photons are interacted in bone located near the exit surface by the photo-electric absorption and only a small amount is incident on the image detector.

The Effect of Different Types of Perceptual Manipulations on the Dimensionality of Automatically Generated Figural Matrices

ERIC Educational Resources Information Center

Arendasy, M.; Sommer, M.

2005-01-01

Two pilot studies (n"1=155, n"2=451) are presented in this article, which were carried out within the development of an item generator for the automatic generation of figural matrices items. The focus of the presented studies was to compare two types of item designs with regard to the effect of variations of the property ''perceptual…

Acoustic scattering of a cylindrical quasi-Gaussian beam with arbitrary incidence focused on a rigid elliptical cylinder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitri, F. G., E-mail: F.G.Mitri@ieee.org

2015-11-14

Using the partial-wave series expansion method in cylindrical coordinates, a formal analytical solution for the acoustical scattering of a 2D cylindrical quasi-Gaussian beam with an arbitrary angle of incidence θ{sub i}, focused on a rigid elliptical cylinder in a non-viscous fluid, is developed. The cylindrical focused beam expression is an exact solution of the Helmholtz equation. The scattering coefficients for the elliptical cylinder are determined by forcing the expression of the total (incident + scattered) field to satisfy the Neumann boundary condition for a rigid immovable surface, and performing the product of matrices involving an inversion procedure. Computations for the matrices elementsmore » require a single numerical integration procedure for each partial-wave mode. Numerical results are performed with particular emphasis on the focusing properties of the incident beam and its angle of incidence with respect to the major axis a of the ellipse as well as the aspect ratio a/b where b is the minor axis (assuming a > b). The method is validated and verified against previous results obtained via the T-matrix for plane waves. The present analysis is the first to consider an acoustical beam on an elliptic cylinder of variable cross-section as opposed to plane waves of infinite extent. Other 2D non-spherical and Chebyshev surfaces are mentioned that may be examined throughout this analytical formalism assuming a small deformation parameter ε.« less

Feasibility for direct rapid energy dispersive X-ray fluorescence (EDXRF) and scattering analysis of complex matrix liquids by partial least squares.

PubMed

Angeyo, K H; Gari, S; Mustapha, A O; Mangala, J M

2012-11-01

The greatest challenge to material characterization by XRF technique is encountered in direct trace analysis of complex matrices. We exploited partial least squares (PLS) in conjunction with energy dispersive X-ray fluorescence and scattering (EDXRFS) spectrometry to rapidly (200 s) analyze lubricating oils. The PLS-EDXRFS method affords non-invasive quality assurance (QA) analysis of complex matrix liquids as it gave optimistic results for both heavy- and low-Z metal additives. Scatter peaks may further be used for QA characterization via the light elements. Copyright © 2012 Elsevier Ltd. All rights reserved.

Bunch-Kaufman factorization for real symmetric indefinite banded matrices

NASA Technical Reports Server (NTRS)

Jones, Mark T.; Patrick, Merrell L.

1989-01-01

The Bunch-Kaufman algorithm for factoring symmetric indefinite matrices was rejected for banded matrices because it destroys the banded structure of the matrix. Herein, it is shown that for a subclass of real symmetric matrices which arise in solving the generalized eigenvalue problem using Lanczos's method, the Bunch-Kaufman algorithm does not result in major destruction of the bandwidth. Space time complexities of the algorithm are given and used to show that the Bunch-Kaufman algorithm is a significant improvement over LU factorization.

Selective Adsorption Resonances in the Scattering of n-H2 p-H2 n-D2 and o-D2 from Ag(111)

NASA Astrophysics Data System (ADS)

Yu, Chien-Fan; Whaley, K. Birgitta; Hogg, Charles S.; Sibener, Steven J.

1983-12-01

Diffractive and rotationally mediated selective adsorption scattering resonances are reported for n-H2 p-H2 n-D2 and o-D2 on Ag(111). Small resonance shifts and line-width differences are observed between n-H2 and p-H2 indicating a weak orientation dependence of the laterally averaged H2/Ag(111) potential. The p-H2 and o-D2 levels were used to determine the isotropic component of this potential, yielding a well depth of ~ 32 meV.

Constructing high-quality bounding volume hierarchies for N-body computation using the acceptance volume heuristic

NASA Astrophysics Data System (ADS)

Olsson, O.

2018-01-01

We present a novel heuristic derived from a probabilistic cost model for approximate N-body simulations. We show that this new heuristic can be used to guide tree construction towards higher quality trees with improved performance over current N-body codes. This represents an important step beyond the current practice of using spatial partitioning for N-body simulations, and enables adoption of a range of state-of-the-art algorithms developed for computer graphics applications to yield further improvements in N-body simulation performance. We outline directions for further developments and review the most promising such algorithms.

New periodic solutions for some planar N + 3-body problems with Newtonian potentials

NASA Astrophysics Data System (ADS)

Yuan, Pengfei; Zhang, Shiqing

2018-03-01

For some planar Newtonian N + 3-body problems, we use variational minimization methods to prove the existence of new periodic solutions satisfying that N bodies chase each other on a curve, and the other 3 bodies chase each other on another curve. From the definition of orbit spaces in our paper, we can find that they are new solutions which are also different from all the examples of Ferrario and Terracini (2004).

Scattering of two spinning black holes in post-Minkowskian gravity, to all orders in spin, and effective-one-body mappings

NASA Astrophysics Data System (ADS)

Vines, Justin

2018-04-01

We demonstrate equivalences, under simple mappings, between the dynamics of three distinct systems—(i) an arbitrary-mass-ratio two-spinning-black-hole system, (ii) a spinning test black hole in a background Kerr spacetime, and (iii) geodesic motion in Kerr—when each is considered in the first post-Minkowskian (1PM) approximation to general relativity, i.e. to linear order G but to all orders in 1/c, and to all orders in the black holes’ spins, with all orders in the multipole expansions of their linearized gravitational fields. This is accomplished via computations of the net results of weak gravitational scattering encounters between two spinning black holes, namely the net O(G) changes in the holes’ momenta and spins as functions of the incoming state. The results are given in remarkably simple closed forms, found by solving effective Mathisson–Papapetrou–Dixon-type equations of motion for a spinning black hole in conjunction with the linearized Einstein equation, with appropriate matching to the Kerr solution. The scattering results fully encode the gauge-invariant content of a canonical Hamiltonian governing binary-black-hole dynamics at 1PM order, for generic (unbound and bound) orbits and spin orientations. We deduce one such Hamiltonian, which reproduces and resums the 1PM parts of all such previous post-Newtonian results, and which directly manifests the equivalences with the test-body limits via simple effective-one-body mappings.

Utilization of the multiple scattering model for the conception of heterogeneous materials with specific electromagnetic properties

NASA Astrophysics Data System (ADS)

Vignéras-Lefebvre, V.; Miane, J. L.; Parneix, J. P.

1993-03-01

A modelisation of the behaviour of heterogeneous structures, made with spherical particles, submitted to microwave fields, using multiple scattering, is presented. First of all, we expose the principle of scattering by a single sphere, using Mie's equations represented in the form of a transfer matrix. This matrix, generalized to a distribution of particles, allows the translation of an average behaviour of the material. As part of the limit of Rayleigh, the value of the effective permittivity thus obtained is compared to experimental results. Une modélisation du comportement de structures hétérogènes composées de particules sphériques, soumises à des champs hyperfréquences, utilisant la multidiffusion, est présentée. Dans un premier temps, nous exposons le principe de la diffusion par une seule sphère en utilisant les équations de Mie représentées sous forme matricielle. Cette matrice généralisée à une distribution de particules permet de traduire un comportement moyen du matériau. Dans le cadre de l'approximation de Rayleigh, la valeur de la permittivité ainsi calculée est comparée à des résultats expérimentaux.

Inverse eigenproblem for R-symmetric matrices and their approximation

NASA Astrophysics Data System (ADS)

Yuan, Yongxin

2009-11-01

Let be a nontrivial involution, i.e., R=R-1[not equal to]±In. We say that is R-symmetric if RGR=G. The set of all -symmetric matrices is denoted by . In this paper, we first give the solvability condition for the following inverse eigenproblem (IEP): given a set of vectors in and a set of complex numbers , find a matrix such that and are, respectively, the eigenvalues and eigenvectors of A. We then consider the following approximation problem: Given an n×n matrix , find such that , where is the solution set of IEP and ||[dot operator]|| is the Frobenius norm. We provide an explicit formula for the best approximation solution by means of the canonical correlation decomposition.

Quasi-Elastic Light Scattering in Ophthalmology

NASA Astrophysics Data System (ADS)

Ansari, Rafat R.

The eye is not just a "window to the soul"; it can also be a "window to the human body." The eye is built like a camera. Light which travels from the cornea to the retina traverses through tissues that are representative of nearly every tissue type and fluid type in the human body. Therefore, it is possible to diagnose ocular and systemic diseases through the eye. Quasi-elastic light scattering (QELS) also known as dynamic light scattering (DLS) is a laboratory technique routinely used in the characterization of macromolecular dispersions. QELS instrumentation has now become more compact, sensitive, flexible, and easy to use. These developments have made QELS/DLS an important tool in ophthalmic research where disease can be detected early and noninvasively before the clinical symptoms appear.

Quantum crystallography: A perspective.

PubMed

Massa, Lou; Matta, Chérif F

2018-06-30

Extraction of the complete quantum mechanics from X-ray scattering data is the ultimate goal of quantum crystallography. This article delivers a perspective for that possibility. It is desirable to have a method for the conversion of X-ray diffraction data into an electron density that reflects the antisymmetry of an N-electron wave function. A formalism for this was developed early on for the determination of a constrained idempotent one-body density matrix. The formalism ensures pure-state N-representability in the single determinant sense. Applications to crystals show that quantum mechanical density matrices of large molecules can be extracted from X-ray scattering data by implementing a fragmentation method termed the kernel energy method (KEM). It is shown how KEM can be used within the context of quantum crystallography to derive quantum mechanical properties of biological molecules (with low data-to-parameters ratio). © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Tensor discriminant color space for face recognition.

PubMed

Wang, Su-Jing; Yang, Jian; Zhang, Na; Zhou, Chun-Guang

2011-09-01

Recent research efforts reveal that color may provide useful information for face recognition. For different visual tasks, the choice of a color space is generally different. How can a color space be sought for the specific face recognition problem? To address this problem, this paper represents a color image as a third-order tensor and presents the tensor discriminant color space (TDCS) model. The model can keep the underlying spatial structure of color images. With the definition of n-mode between-class scatter matrices and within-class scatter matrices, TDCS constructs an iterative procedure to obtain one color space transformation matrix and two discriminant projection matrices by maximizing the ratio of these two scatter matrices. The experiments are conducted on two color face databases, AR and Georgia Tech face databases, and the results show that both the performance and the efficiency of the proposed method are better than those of the state-of-the-art color image discriminant model, which involve one color space transformation matrix and one discriminant projection matrix, specifically in a complicated face database with various pose variations.

Threshold e- p⟶ nνe scattering and the electron neutrino mass

NASA Astrophysics Data System (ADS)

Ciborowski, Jacek; Rembieliński, Jakub

2017-12-01

The most precise measurement of the electron neutrino mass has been obtained from the shape of the electron energy spectrum near the endpoint in tritium decay. The Mainz and Troitsk experiments indicated an excess instead of expected depletion of counts in that region. Results derived from such measurements are subject to numerous atomic corrections which are absent in the scattering e- p ⟶ nνe. This new idea is presented in the article, with its advantages and difficulties, and is compared to the method of tritium decay.

A combined finite element-boundary element formulation for solution of axially symmetric bodies

NASA Technical Reports Server (NTRS)

Collins, Jeffrey D.; Volakis, John L.

1991-01-01

A new method is presented for the computation of electromagnetic scattering from axially symmetric bodies. To allow the simulation of inhomogeneous cross sections, the method combines the finite element and boundary element techniques. Interior to a fictitious surface enclosing the scattering body, the finite element method is used which results in a sparce submatrix, whereas along the enclosure the Stratton-Chu integral equation is enforced. By choosing the fictitious enclosure to be a right circular cylinder, most of the resulting boundary integrals are convolutional and may therefore be evaluated via the FFT with which the system is iteratively solved. In view of the sparce matrix associated with the interior fields, this reduces the storage requirement of the entire system to O(N) making the method attractive for large scale computations. The details of the corresponding formulation and its numerical implementation are described.

Symmetries and "simple" solutions of the classical n-body problem

NASA Astrophysics Data System (ADS)

Chenciner, Alain

2006-03-01

The Lagrangian of the classical n-body problem has well known symmetries: isometries of the ambient Euclidean space (translations, rotations, reflexions) and changes of scale coming from the homogeneity of the potential. To these symmetries are associated "simple" solutions of the problem, the so-called homographic motions, which play a basic role in the global understanding of the dynamics. The classical subproblems (planar, isosceles) are also consequences of the existence of symmetries: invariance under reflexion through a plane in the first case, invariance under exchange of two equal masses in the second. In these two cases, the symmetry acts at the level of the "shape space" (the oriented one in the first case) whose existence is the main difference between the 2-body problem and the (n ≥ 3)-body problem. These symmetries of the Lagrangian imply symmetries of the action functional, which is defined on the space of regular enough loops of a given period in the configuration space of the problem. Minimization of the action under well-chosen symmetry constraints leads to remarkable solutions of the n-body problem which may also be called simple and could play after the homographic ones the role of organizing centers in the global dynamics. In [13] and [16], I have given a survey of the new classes of solutions which had been obtained in this way, mainly choreographies of n equal masses in a plane or in space and generalized Hip-Hops of at least 4 arbitrary masses in space. I give here an updated overview of the results and a quick glance at the methods of proofs.

Interband coupling and transport interband scattering in s ± superconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kogan, Vladimir; Prozorov, Ruslan

A two-band model with repulsive interband coupling and interband transport (potential) scattering is considered to elucidate their effects on material properties. In agreement with previous work, we find that the bands order parameters Δ 1,2 differ and the large is at the band with a smaller normal density of states (DOS), N n2 < N n1. However, the bands energy gaps, as determined by the energy dependence of the DOS, are equal due to scattering. For each temperature, the gaps turn zero at a certain critical interband scattering rate, i.e. for strong enough scattering the model material becomes gappless. Inmore » the gapless state, the DOS at the band 2 is close to the normal state value, whereas at the band 1 it has a V-shape with non-zero minimum. When the normal bands DOS' are mismatched, N n1 6= N n2, the critical temperature T c is suppressed even in the absence of interband scattering, T c(N n1) has a dome-like shape. With increasing interband scattering, the London penetration depth at low temperatures evolves from being exponentially at to the powerlaw and even to near linear behavior in the gapless state, the latter being easily misinterpreted as caused by order parameter nodes.« less

Application of electrically invisible antennas to the Modulated Scatterer Technique

DOE PAGES

Crocker, Dylan A.; Donnell, Kristen M.

2015-09-16

The modulated scatterer technique (MST) has shown promise for applications in microwave imaging, electric field mapping, and materials characterization. Traditionally, MST scatterers are dipoles centrally loaded with an element capable of modulation (e.g., a p-i-n diode). By modulating the load element, signals scattered from the MST scatterer are also modulated. However, due to the small size of such scatterers, it can be difficult to reliably detect the modulated signal. Increasing the modulation depth (MD; a parameter related to how well the scatterer modulates the scattered signal) may improve the detectability of the scattered signal. In an effort to improve themore » MD, the concept of electrically invisible antennas is applied to the design of MST scatterers. Our paper presents simulations and measurements of MST scatterers that have been designed to be electrically invisible during the reverse bias state of the modulated element (a p-i-n diode in this case), while producing detectable scattering during the forward bias state (i.e., operate in an electrically visible state). Furthermore, the results using the new design show significant improvement to the MD of the scattered signal as compared with a traditional MST scatterer (i.e., dipole centrally loaded with a p-i-n diode).« less

Excitons emissions and Raman scattering of ZnO nanoparticles embedded in BaF2 matrices by reactive magnetron sputtering.

PubMed

Zang, C H; Su, J F; Liu, Y C; Tang, C J; Fang, S J; Zhang, D M; Zhang, Y S

2011-11-01

ZnO nanoparticles embedded in BaF2 matrix were fabricated by rf magnetic sputtering technology. The optical properties of high quality ZnO nanoparticles, thermally post treated in a N2 atmosphere, were investigated by temperature-dependence photoluminescence measurement. Free exciton and localized exciton were observed at the low temperature. Free exciton peak was at 3.374 eV and localized exciton peak was at 3.420 eV, dominating the PL spectrum at 77 K. Free exciton transition was observed at 3.310 eV at room temperature, whereas the localized exciton transition was at 3.378 eV. The multiple-phonon Raman scattering spectrum showed that ZnO nanoparticles embedded in BaF2 matrix had a large deformation energy originated from lattice mismatch between ZnO and BaF2 matrix. Analysis of the fitting results from the temperature dependence of FWHM of ZnO exciton illustrated that the large value of gamma(ph) was good qualitative agreement with the large deformation potential.

Particle number dependence in the non-linear evolution of N-body self-gravitating systems

NASA Astrophysics Data System (ADS)

Benhaiem, D.; Joyce, M.; Sylos Labini, F.; Worrakitpoonpon, T.

2018-01-01

Simulations of purely self-gravitating N-body systems are often used in astrophysics and cosmology to study the collisionless limit of such systems. Their results for macroscopic quantities should then converge well for sufficiently large N. Using a study of the evolution from a simple space of spherical initial conditions - including a region characterized by so-called 'radial orbit instability' - we illustrate that the values of N at which such convergence is obtained can vary enormously. In the family of initial conditions we study, good convergence can be obtained up to a few dynamical times with N ∼ 103 - just large enough to suppress two body relaxation - for certain initial conditions, while in other cases such convergence is not attained at this time even in our largest simulations with N ∼ 105. The qualitative difference is due to the stability properties of fluctuations introduced by the N-body discretisation, of which the initial amplitude depends on N. We discuss briefly why the crucial role which such fluctuations can potentially play in the evolution of the N body system could, in particular, constitute a serious problem in cosmological simulations of dark matter.

Coupled π π , K K ¯ scattering in P -wave and the ρ resonance from lattice QCD

DOE PAGES

Wilson, David J.; Briceño, Raúl A.; Dudek, Jozef J.; ...

2015-11-02

In this study, we determine elastic and coupled-channel amplitudes for isospin-1 meson-meson scattering inmore » $P$-wave, by calculating correlation functions using lattice QCD with light quark masses such that $$m_\\pi = 236$$ MeV in a cubic volume of $$\\sim (4 \\,\\mathrm{fm})^3$$. Variational analyses of large matrices of correlation functions computed using operator constructions resembling $$\\pi\\pi$$, $$K\\overline{K}$$ and $$q\\bar{q}$$, in several moving frames and several lattice irreducible representations, leads to discrete energy spectra from which scattering amplitudes are extracted. In the elastic $$\\pi\\pi$$ scattering region we obtain a detailed energy-dependence for the phase-shift, corresponding to a $$\\rho$$ resonance, and we extend the analysis into the coupled-channel $$K\\overline{K}$$ region for the first time, finding a small coupling between the channels.« less

Estimation for the Linear Model With Uncertain Covariance Matrices

NASA Astrophysics Data System (ADS)

Zachariah, Dave; Shariati, Nafiseh; Bengtsson, Mats; Jansson, Magnus; Chatterjee, Saikat

2014-03-01

We derive a maximum a posteriori estimator for the linear observation model, where the signal and noise covariance matrices are both uncertain. The uncertainties are treated probabilistically by modeling the covariance matrices with prior inverse-Wishart distributions. The nonconvex problem of jointly estimating the signal of interest and the covariance matrices is tackled by a computationally efficient fixed-point iteration as well as an approximate variational Bayes solution. The statistical performance of estimators is compared numerically to state-of-the-art estimators from the literature and shown to perform favorably.

Noisy covariance matrices and portfolio optimization

NASA Astrophysics Data System (ADS)

Pafka, S.; Kondor, I.

2002-05-01

According to recent findings [#!bouchaud!#,#!stanley!#], empirical covariance matrices deduced from financial return series contain such a high amount of noise that, apart from a few large eigenvalues and the corresponding eigenvectors, their structure can essentially be regarded as random. In [#!bouchaud!#], e.g., it is reported that about 94% of the spectrum of these matrices can be fitted by that of a random matrix drawn from an appropriately chosen ensemble. In view of the fundamental role of covariance matrices in the theory of portfolio optimization as well as in industry-wide risk management practices, we analyze the possible implications of this effect. Simulation experiments with matrices having a structure such as described in [#!bouchaud!#,#!stanley!#] lead us to the conclusion that in the context of the classical portfolio problem (minimizing the portfolio variance under linear constraints) noise has relatively little effect. To leading order the solutions are determined by the stable, large eigenvalues, and the displacement of the solution (measured in variance) due to noise is rather small: depending on the size of the portfolio and on the length of the time series, it is of the order of 5 to 15%. The picture is completely different, however, if we attempt to minimize the variance under non-linear constraints, like those that arise e.g. in the problem of margin accounts or in international capital adequacy regulation. In these problems the presence of noise leads to a serious instability and a high degree of degeneracy of the solutions.

Nano-Fiber Reinforced Enhancements in Composite Polymer Matrices

NASA Technical Reports Server (NTRS)

Chamis, Christos C.

2009-01-01

Nano-fibers are used to reinforce polymer matrices to enhance the matrix dependent properties that are subsequently used in conventional structural composites. A quasi isotropic configuration is used in arranging like nano-fibers through the thickness to ascertain equiaxial enhanced matrix behavior. The nano-fiber volume ratios are used to obtain the enhanced matrix strength properties for 0.01,0.03, and 0.05 nano-fiber volume rates. These enhanced nano-fiber matrices are used with conventional fiber volume ratios of 0.3 and 0.5 to obtain the composite properties. Results show that nano-fiber enhanced matrices of higher than 0.3 nano-fiber volume ratio are degrading the composite properties.

Atom-dimer scattering in a heteronuclear mixture with a finite intraspecies scattering length

NASA Astrophysics Data System (ADS)

Gao, Chao; Zhang, Peng

2018-04-01

We study the three-body problem of two ultracold identical bosonic atoms (denoted by B ) and one extra atom (denoted by X ), where the scattering length aB X between each bosonic atom and atom X is resonantly large and positive. We calculate the scattering length aad between one bosonic atom and the shallow dimer formed by the other bosonic atom and atom X , and investigate the effect induced by the interaction between the two bosonic atoms. We find that even if this interaction is weak (i.e., the corresponding scattering length aB B is of the same order of the van der Waals length rvdW or even smaller), it can still induce a significant effect for the atom-dimer scattering length aad. Explicitly, an atom-dimer scattering resonance can always occur when the value of aB B varies in the region with | aB B|≲ rvdW . As a result, both the sign and the absolute value of aad, as well as the behavior of the aad-aB X function, depends sensitively on the exact value of aB B. Our results show that, for a good quantitative theory, the intraspecies interaction is required to be taken into account for this heteronuclear system, even if this interaction is weak.

Maple procedures for the coupling of angular momenta. IX. Wigner D-functions and rotation matrices

NASA Astrophysics Data System (ADS)

Pagaran, J.; Fritzsche, S.; Gaigalas, G.

2006-04-01

The Wigner D-functions, Dpqj(α,β,γ), are known for their frequent use in quantum mechanics. Defined as the matrix elements of the rotation operator Rˆ(α,β,γ) in R and parametrized in terms of the three Euler angles α, β, and γ, these functions arise not only in the transformation of tensor components under the rotation of the coordinates, but also as the eigenfunctions of the spherical top. In practice, however, the use of the Wigner D-functions is not always that simple, in particular, if expressions in terms of these and other functions from the theory of angular momentum need to be simplified before some computations can be carried out in detail. To facilitate the manipulation of such Racah expressions, here we present an extension to the RACAH program [S. Fritzsche, Comput. Phys. Comm. 103 (1997) 51] in which the properties and the algebraic rules of the Wigner D-functions and reduced rotation matrices are implemented. Care has been taken to combine the standard knowledge about the rotation matrices with the previously implemented rules for the Clebsch-Gordan coefficients, Wigner n-j symbols, and the spherical harmonics. Moreover, the application of the program has been illustrated below by means of three examples. Program summaryTitle of program:RACAH Catalogue identifier:ADFv_9_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADFv_9_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Catalogue identifier of previous version: ADFW, ADHW, title RACAH Journal reference of previous version(s): S. Fritzsche, Comput. Phys. Comm. 103 (1997) 51; S. Fritzsche, S. Varga, D. Geschke, B. Fricke, Comput. Phys. Comm. 111 (1998) 167; S. Fritzsche, T. Inghoff, M. Tomaselli, Comput. Phys. Comm. 153 (2003) 424. Does the new version supersede the previous one: Yes, in addition to the spherical harmonics and recoupling coefficients, the program now supports also the occurrence of the Wigner rotation matrices in the algebraic

Simulation of n-qubit quantum systems. IV. Parametrizations of quantum states, matrices and probability distributions

NASA Astrophysics Data System (ADS)

Radtke, T.; Fritzsche, S.

2008-11-01

Entanglement is known today as a key resource in many protocols from quantum computation and quantum information theory. However, despite the successful demonstration of several protocols, such as teleportation or quantum key distribution, there are still many open questions of how entanglement affects the efficiency of quantum algorithms or how it can be protected against noisy environments. The investigation of these and related questions often requires a search or optimization over the set of quantum states and, hence, a parametrization of them and various other objects. To facilitate this kind of studies in quantum information theory, here we present an extension of the FEYNMAN program that was developed during recent years as a toolbox for the simulation and analysis of quantum registers. In particular, we implement parameterizations of hermitian and unitary matrices (of arbitrary order), pure and mixed quantum states as well as separable states. In addition to being a prerequisite for the study of many optimization problems, these parameterizations also provide the necessary basis for heuristic studies which make use of random states, unitary matrices and other objects. Program summaryProgram title: FEYNMAN Catalogue identifier: ADWE_v4_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWE_v4_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 24 231 No. of bytes in distributed program, including test data, etc.: 1 416 085 Distribution format: tar.gz Programming language: Maple 11 Computer: Any computer with Maple software installed Operating system: Any system that supports Maple; program has been tested under Microsoft Windows XP, Linux Classification: 4.15 Does the new version supersede the previous version?: Yes Nature of problem: During the last decades

Orbital Dynamics of Exomoons During Planet–Planet Scattering

NASA Astrophysics Data System (ADS)

Hong, Yu-Cian; Lunine, Jonathan I.; Nicholson, Philip; Raymond, Sean N.

2018-04-01

Planet–planet scattering is the leading mechanism to explain the broad eccentricity distribution of observed giant exoplanets. Here we study the orbital stability of primordial giant planet moons in this scenario. We use N-body simulations including realistic oblateness and evolving spin evolution for the giant planets. We find that the vast majority (~80%–90% across all our simulations) of orbital parameter space for moons is destabilized. There is a strong radial dependence, as moons past are systematically removed. Closer-in moons on Galilean-moon-like orbits (<0.04 R Hill) have a good (~20%–40%) chance of survival. Destabilized moons may undergo a collision with the star or a planet, be ejected from the system, be captured by another planet, be ejected but still orbiting its free-floating host planet, or survive on heliocentric orbits as "planets." The survival rate of moons increases with the host planet mass but is independent of the planet's final (post-scattering) orbits. Based on our simulations, we predict the existence of an abundant galactic population of free-floating (former) moons.

The asymptotic spectra of banded Toeplitz and quasi-Toeplitz matrices

NASA Technical Reports Server (NTRS)

Beam, Richard M.; Warming, Robert F.

1991-01-01

Toeplitz matrices occur in many mathematical, as well as, scientific and engineering investigations. This paper considers the spectra of banded Toeplitz and quasi-Toeplitz matrices with emphasis on non-normal matrices of arbitrarily large order and relatively small bandwidth. These are the type of matrices that appear in the investigation of stability and convergence of difference approximations to partial differential equations. Quasi-Toeplitz matrices are the result of non-Dirichlet boundary conditions for the difference approximations. The eigenvalue problem for a banded Toeplitz or quasi-Toeplitz matrix of large order is, in general, analytically intractable and (for non-normal matrices) numerically unreliable. An asymptotic (matrix order approaches infinity) approach partitions the eigenvalue analysis of a quasi-Toeplitz matrix into two parts, namely the analysis for the boundary condition independent spectrum and the analysis for the boundary condition dependent spectrum. The boundary condition independent spectrum is the same as the pure Toeplitz matrix spectrum. Algorithms for computing both parts of the spectrum are presented. Examples are used to demonstrate the utility of the algorithms, to present some interesting spectra, and to point out some of the numerical difficulties encountered when conventional matrix eigenvalue routines are employed for non-normal matrices of large order. The analysis for the Toeplitz spectrum also leads to a diagonal similarity transformation that improves conventional numerical eigenvalue computations. Finally, the algorithm for the asymptotic spectrum is extended to the Toeplitz generalized eigenvalue problem which occurs, for example, in the stability of Pade type difference approximations to differential equations.

Non-destructive examination system of vitreous body

NASA Astrophysics Data System (ADS)

Shibata, Takuma; Gong, Jin; Watanabe, Yosuke; Kabir, M. Hasnat; Masato, Makino; Furukawa, Hidemitsu; Nishitsuka, Koichi

2014-04-01

Eyeball plays a quite important role in acquiring the vision. Vitreous body occupies the largest part of the eyeball and consists of biological, elastic, transparent, gel materials. In the present medical examination, the non-destructive examination method of the vitreous body has not been well established. Here, we focus on an application of dynamic light scattering to this topic. We tried to apply our lab-made apparatus, scanning microscopic light scattering (SMILS), which was specially designed for observing the nanometer-scale network structure in gel materials. In order to examine the vitreous body using SMILS method, a commercial apparatus, nano Partica (Horiba Co. Ltd.) was also customized. We analyzed vitreous body using both the SMILS and the customized nano Partica. We successfully examined the vitreous bodies of healthy pigs in non-destructive way.

Crosslinked type II collagen matrices: preparation, characterization, and potential for cartilage engineering.

PubMed

Pieper, J S; van der Kraan, P M; Hafmans, T; Kamp, J; Buma, P; van Susante, J L C; van den Berg, W B; Veerkamp, J H; van Kuppevelt, T H

2002-08-01

The limited intrinsic repair capacity of articular cartilage has stimulated continuing efforts to develop tissue engineered analogues. Matrices composed of type II collagen and chondroitin sulfate (CS), the major constituents of hyaline cartilage, may create an appropriate environment for the generation of cartilage-like tissue. In this study, we prepared, characterized, and evaluated type 11 collagen matrices with and without CS. Type II collagen matrices were prepared using purified, pepsin-treated, type II collagen. Techniques applied to prepare type I collagen matrices were found unsuitable for type II collagen. Crosslinking of collagen and covalent attachment of CS was performed using 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide. Porous matrices were prepared by freezing and lyophilization, and their physico-chemical characteristics (degree of crosslinking, denaturing temperature, collagenase-resistance, amount of CS incorporated) established. Matrices were evaluated for their capacity to sustain chondrocyte proliferation and differentiation in vitro. After 7 d of culture, chondrocytes were mainly located at the periphery of the matrices. In contrast to type I collagen, type II collagen supported the distribution of cells throughout the matrix. After 14 d of culture, matrices were surfaced with a cartilagenous-like layer, and occasionally clusters of chondrocytes were present inside the matrix. Chondrocytes proliferated and differentiated as indicated by biochemical analyses, ultrastructural observations, and reverse transcriptase PCR for collagen types I, II and X. No major differences were observed with respect to the presence or absence of CS in the matrices.

Asymptotics of eigenvalues and eigenvectors of Toeplitz matrices

NASA Astrophysics Data System (ADS)

Böttcher, A.; Bogoya, J. M.; Grudsky, S. M.; Maximenko, E. A.

2017-11-01

Analysis of the asymptotic behaviour of the spectral characteristics of Toeplitz matrices as the dimension of the matrix tends to infinity has a history of over 100 years. For instance, quite a number of versions of Szegő's theorem on the asymptotic behaviour of eigenvalues and of the so-called strong Szegő theorem on the asymptotic behaviour of the determinants of Toeplitz matrices are known. Starting in the 1950s, the asymptotics of the maximum and minimum eigenvalues were actively investigated. However, investigation of the individual asymptotics of all the eigenvalues and eigenvectors of Toeplitz matrices started only quite recently: the first papers on this subject were published in 2009-2010. A survey of this new field is presented here. Bibliography: 55 titles.

Rayleigh scattering in an emitter-nanofiber-coupling system

NASA Astrophysics Data System (ADS)

Tang, Shui-Jing; Gao, Fei; Xu, Da; Li, Yan; Gong, Qihuang; Xiao, Yun-Feng

2017-04-01

Scattering is a general process in both fundamental and applied physics. In this paper, we investigate Rayleigh scattering of a solid-state-emitter coupled to a nanofiber, by S -matrix-like theory in k -space description. Under this model, both Rayleigh scattering and dipole interaction are studied between a two-level artificial atom embedded in a nanocrystal and fiber modes (guided and radiation modes). It is found that Rayleigh scattering plays a critical role in the transport properties and quantum statistics of photons. On the one hand, Rayleigh scattering produces the transparency in the optical transmitted field of the nanofiber, accompanied by the change of atomic phase, population, and frequency shift. On the other hand, the interference between two kinds of scattering fields by Rayleigh scattering and dipole transition modifies the photon statistics (second-order autocorrelation function) of output fields, showing a strong wavelength dependence. This study provides guidance for the solid-state emitter acting as a single-photon source and can be extended to explore the scattering effect in many-body physics.

Analyzing power Ay(θ) of n-3He elastic scattering between 1.60 and 5.54 MeV.

PubMed

Esterline, J; Tornow, W; Deltuva, A; Fonseca, A C

2013-04-12

Comprehensive and high-accuracy n-3He elastic scattering analyzing power Ay(θ) angular distributions were obtained at five incident neutron energies between 1.60 and 5.54 MeV. The data are compared to rigorous four-nucleon calculations using high-precision nucleon-nucleon potential models; three-nucleon force effects are found to be very small. The agreement between data and calculations is fair at the lower energies and becomes less satisfactory with increasing neutron energy. Comparison to p-3He scattering over the same energy range exhibits unexpectedly large isospin effects.

Perceptual Optimization of DCT Color Quantization Matrices

NASA Technical Reports Server (NTRS)

Watson, Andrew B.; Statler, Irving C. (Technical Monitor)

1994-01-01

Many image compression schemes employ a block Discrete Cosine Transform (DCT) and uniform quantization. Acceptable rate/distortion performance depends upon proper design of the quantization matrix. In previous work, we showed how to use a model of the visibility of DCT basis functions to design quantization matrices for arbitrary display resolutions and color spaces. Subsequently, we showed how to optimize greyscale quantization matrices for individual images, for optimal rate/perceptual distortion performance. Here we describe extensions of this optimization algorithm to color images.

An Advanced N -body Model for Interacting Multiple Stellar Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brož, Miroslav

We construct an advanced model for interacting multiple stellar systems in which we compute all trajectories with a numerical N -body integrator, namely the Bulirsch–Stoer from the SWIFT package. We can then derive various observables: astrometric positions, radial velocities, minima timings (TTVs), eclipse durations, interferometric visibilities, closure phases, synthetic spectra, spectral energy distribution, and even complete light curves. We use a modified version of the Wilson–Devinney code for the latter, in which the instantaneous true phase and inclination of the eclipsing binary are governed by the N -body integration. If all of these types of observations are at one’s disposal,more » a joint χ {sup 2} metric and an optimization algorithm (a simplex or simulated annealing) allow one to search for a global minimum and construct very robust models of stellar systems. At the same time, our N -body model is free from artifacts that may arise if mutual gravitational interactions among all components are not self-consistently accounted for. Finally, we present a number of examples showing dynamical effects that can be studied with our code and we discuss how systematic errors may affect the results (and how to prevent this from happening).« less

Non-equilibrium many-body dynamics following a quantum quench

NASA Astrophysics Data System (ADS)

Vyas, Manan

2017-12-01

We study analytically and numerically the non-equilibrium dynamics of an isolated interacting many-body quantum system following a random quench. We model the system Hamiltonian by Embedded Gaussian Orthogonal Ensemble (EGOE) of random matrices with one plus few-body interactions for fermions. EGOE are paradigmatic models to study the crossover from integrability to chaos in interacting many-body quantum systems. We obtain a generic formulation, based on spectral variances, for describing relaxation dynamics of survival probabilities as a function of rank of interactions. Our analytical results are in good agreement with numerics.

Calibration and temperature correction of heat dissipation matric potential sensors

USGS Publications Warehouse

Flint, A.L.; Campbell, G.S.; Ellett, K.M.; Calissendorff, C.

2002-01-01

This paper describes how heat dissipation sensors, used to measure soil water matric potential, were analyzed to develop a normalized calibration equation and a temperature correction method. Inference of soil matric potential depends on a correlation between the variable thermal conductance of the sensor's porous ceramic and matric poten-tial. Although this correlation varies among sensors, we demonstrate a normalizing procedure that produces a single calibration relationship. Using sensors from three sources and different calibration methods, the normalized calibration resulted in a mean absolute error of 23% over a matric potential range of -0.01 to -35 MPa. Because the thermal conductivity of variably saturated porous media is temperature dependent, a temperature correction is required for application of heat dissipation sensors in field soils. A temperature correction procedure is outlined that reduces temperature dependent errors by 10 times, which reduces the matric potential measurement errors by more than 30%. The temperature dependence is well described by a thermal conductivity model that allows for the correction of measurements at any temperature to measurements at the calibration temperature.

ON THE EFFECT OF GIANT PLANETS ON THE SCATTERING OF PARENT BODIES OF IRON METEORITE FROM THE TERRESTRIAL PLANET REGION INTO THE ASTEROID BELT: A CONCEPT STUDY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haghighipour, Nader; Scott, Edward R. D., E-mail: nader@ifa.hawaii.edu

2012-04-20

In their model for the origin of the parent bodies of iron meteorites, Bottke et al. proposed differentiated planetesimals, formed in 1-2 AU during the first 1.5 Myr, as the parent bodies, and suggested that these objects and their fragments were scattered into the asteroid belt as a result of interactions with planetary embryos. Although viable, this model does not include the effect of a giant planet that might have existed or been growing in the outer regions. We present the results of a concept study where we have examined the effect of a planetary body in the orbit ofmore » Jupiter on the early scattering of planetesimals from the terrestrial region into the asteroid belt. We integrated the orbits of a large battery of planetesimals in a disk of planetary embryos and studied their evolutions for different values of the mass of the planet. Results indicate that when the mass of the planet is smaller than 10 M{sub Circled-Plus }, its effects on the interactions among planetesimals and planetary embryos are negligible. However, when the planet mass is between 10 and 50 M{sub Circled-Plus }, simulations point to a transitional regime with {approx}50 M{sub Circled-Plus} being the value for which the perturbing effect of the planet can no longer be ignored. Simulations also show that further increase of the mass of the planet strongly reduces the efficiency of the scattering of planetesimals from the terrestrial planet region into the asteroid belt. We present the results of our simulations and discuss their possible implications for the time of giant planet formation.« less

Inclusive neutrino scattering off the deuteron from threshold to GeV energies

NASA Astrophysics Data System (ADS)

Shen, G.; Marcucci, L. E.; Carlson, J.; Gandolfi, S.; Schiavilla, R.

2012-09-01

Background: Neutrino-nucleus quasi-elastic scattering is crucial to interpret the neutrino oscillation results in long baseline neutrino experiments. There are rather large uncertainties in the cross section, due to insufficient knowledge on the role of two-body weak currents.Purpose: Determine the role of two-body weak currents in neutrino-deuteron quasi-elastic scattering up to GeV energies.Methods: Calculate cross sections for inclusive neutrino scattering off deuteron induced by neutral and charge-changing weak currents, from threshold up to GeV energies, using the Argonne v18 potential and consistent nuclear electroweak currents with one- and two-body terms.Results: Two-body contributions are found to be small, and increase the cross sections obtained with one-body currents by less than 10% over the whole range of energies. Total cross sections obtained by describing the final two-nucleon states with plane waves differ negligibly, for neutrino energies ≳ MeV, from those in which interaction effects in these states are fully accounted for. The sensitivity of the calculated cross sections to different models for the two-nucleon potential and/or two-body terms in the weak current is found to be weak. Comparing cross sections to those obtained in a naive model in which the deuteron is taken to consist of a free proton and neutron at rest, nuclear structure effects are illustrated to be non-negligible.Conclusion: Contributions of two-body currents in neutrino-deuteron quasi-elastic scattering up to GeV are found to be smaller than 10%. Finally, it should be stressed that the results reported in this work do not include pion production channels.

Rotator Phases of n-Heptane under High Pressure: Raman Scattering and X-ray Diffraction Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

C Ma; Q Zhou; F Li

2011-12-31

We performed high-pressure Raman scattering and angle-dispersive synchrotron X-ray diffraction measurements on n-heptane at room temperature. It has been found that n-heptane undergoes a liquid to rotator phase III (R{sub III}) transition at 1.2 GPa and then transforms into another rotator phase R{sub IV} at about 3 GPa. As the pressure reaches 7.5 GPa, a transition from an orientationally disordered R{sub IV} phase to an ordered crystalline state starts and is completed around 14.5 GPa. Our results clearly present the high-pressure phase transition sequence (liquid-R{sub III}-R{sub IV}-crystal) of n-heptane, similar to that of normal alkanes.

Organized chaos: scatter in the relation between stellar mass and halo mass in small galaxies

NASA Astrophysics Data System (ADS)

Garrison-Kimmel, Shea; Bullock, James S.; Boylan-Kolchin, Michael; Bardwell, Emma

2017-01-01

We use Local Group galaxy counts together with the ELVIS N-body simulations to explore the relationship between the scatter and slope in the stellar mass versus halo mass relation at low masses, M⋆ ≃ 105-108 M⊙. Assuming models with lognormal scatter about a median relation of the form M_star ∝ M_halo^α, the preferred log-slope steepens from α ≃ 1.8 in the limit of zero scatter to α ≃ 2.6 in the case of 2 dex of scatter in M⋆ at fixed halo mass. We provide fitting functions for the best-fitting relations as a function of scatter, including cases where the relation becomes increasingly stochastic with decreasing mass. We show that if the scatter at fixed halo mass is large enough (≳ 1 dex) and if the median relation is steep enough (α ≳ 2), then the `too-big-to-fail' problem seen in the Local Group can be self-consistently eliminated in about ˜5-10 per cent of realizations. This scenario requires that the most massive subhaloes host unobservable ultra-faint dwarfs fairly often; we discuss potentially observable signatures of these systems. Finally, we compare our derived constraints to recent high-resolution simulations of dwarf galaxy formation in the literature. Though simulation-to-simulation scatter in M⋆ at fixed Mhalo is large among different authors (˜2 dex), individual codes produce relations with much less scatter and usually give relations that would overproduce local galaxy counts.

Study of morphological changes in scattering and optically anisotropic medium through correlation images

NASA Astrophysics Data System (ADS)

Jain, Neha; Shukla, Prashant; Singh, Jai

2018-05-01

Correlation images are very useful in determining the morphological changes. We have investigated the correlation image analysis on depolarization and retardance matrices of polystyrene and gelatine samples respectively. We observed that that correlation images have a potential to show a significant variation with change in the concentration of samples (polystyrene and gelatine). For polystyrene microspheres the correlation value decreases with increasing scattering coefficient. In gelatine samples the correlation also decreases with sample concentration. This variation in correlation for retardance shows the change in a birefringence property of gelatine solution.

The Approximation of Two-Mode Proximity Matrices by Sums of Order-Constrained Matrices.

ERIC Educational Resources Information Center

Hubert, Lawrence; Arabie, Phipps

1995-01-01

A least-squares strategy is proposed for representing a two-mode proximity matrix as an approximate sum of a small number of matrices that satisfy certain simple order constraints on their entries. The primary class of constraints considered defines Q-forms for particular conditions in a two-mode matrix. (SLD)

Search for elemental and mineral biomarkers using inelastic neutron scattering spectroscopy (INSS)

NASA Astrophysics Data System (ADS)

Wielopolski, Lucian; Hoover, Richard B.; Mitra, Sudeep

2004-02-01

Life on Earth is characterized by a select group of low Z elements: C, H, N, O, P, K, S, Na, Cl. The presence of these elements and their ratios can provide indications of possible biogenicity and thus they may constitute valuable biomarkers that may help determine the best locations to seek more definitive evidence of life. We discuss the possible applications and significance of the inelastic neutron scattering induced gamma spectroscopy (INSGS) for future Astrobiology Missions to Mars or other solar System bodies. The general requirements and capabilities of the proposed approach are presented.

CUBE: Information-optimized parallel cosmological N-body simulation code

NASA Astrophysics Data System (ADS)

Yu, Hao-Ran; Pen, Ue-Li; Wang, Xin

2018-05-01

CUBE, written in Coarray Fortran, is a particle-mesh based parallel cosmological N-body simulation code. The memory usage of CUBE can approach as low as 6 bytes per particle. Particle pairwise (PP) force, cosmological neutrinos, spherical overdensity (SO) halofinder are included.

Quantum non-Abelian hydrodynamics: Anyonic or spin-orbital entangled liquids, nonunitarity of scattering matrix and charge fractionalization

NASA Astrophysics Data System (ADS)

Pareek, Tribhuvan Prasad

2015-09-01

In this article, we develop an exact (nonadiabatic, nonperturbative) density matrix scattering theory for a two component quantum liquid which interacts or scatters off from a generic spin-dependent quantum potential. The generic spin dependent quantum potential [Eq. (1)] is a matrix potential, hence, adiabaticity criterion is ill-defined. Therefore the full matrix potential should be treated nonadiabatically. We succeed in doing so using the notion of vectorial matrices which allows us to obtain an exact analytical expression for the scattered density matrix (SDM), ϱsc [Eq. (30)]. We find that the number or charge density in scattered fluid, Tr(ϱsc), expressions in Eqs. (32) depends on nontrivial quantum interference coefficients, Qα β 0ijk, which arises due to quantum interference between spin-independent and spin-dependent scattering amplitudes and among spin-dependent scattering amplitudes. Further it is shown that Tr(ϱsc) can be expressed in a compact form [Eq. (39)] where the effect of quantum interference coefficients can be included using a vector Qαβ, which allows us to define a vector order parameterQ. Since the number density is obtained using an exact scattered density matrix, therefore, we do not need to prove that Q is non-zero. However, for sake of completeness, we make detailed mathematical analysis for the conditions under which the vector order parameterQ would be zero or nonzero. We find that in presence of spin-dependent interaction the vector order parameterQ is necessarily nonzero and is related to the commutator and anti-commutator of scattering matrix S with its dagger S† [Eq. (78)]. It is further shown that Q≠0, implies four physically equivalent conditions,i.e., spin-orbital entanglement is nonzero, non-Abelian scattering phase, i.e., matrices, scattering matrix is nonunitary and the broken time reversal symmetry for SDM. This also implies that quasi particle excitation are anyonic in nature, hence, charge fractionalization is a

Release and diffusional modeling of metronidazole lipid matrices.

PubMed

Ozyazici, Mine; Gökçe, Evren H; Ertan, Gökhan

2006-07-01

In this study, the first aim was to investigate the swelling and relaxation properties of lipid matrix on diffusional exponent (n). The second aim was to determine the desired release profile of metronidazole lipid matrix tablets. We prepared metronidazole lipid matrix granules using Carnauba wax, Beeswax, Stearic acid, Cutina HR, Precirol ATO 5, and Compritol ATO 888 by hot fusion method and pressed the tablets of these granules. In vitro release test was performed using a standard USP dissolution apparatus I (basket method) with a stirring rate of 100 rpm at 37 degrees C in 900 ml of 0.1 N hydrochloric acid, adjusted to pH 1.2, as medium for the formulations' screening. Hardness, diameter-height ratio, friability, and swelling ratio were determined. Target release profile of metronidazole was also drawn. Stearic acid showed the highest and Carnauba wax showed the lowest release rates in all formulations used. Swelling ratios were calculated after the dissolution of tablets as 9.24%, 6.03%, 1.74%, and 1.07% for Cutina HR, Beeswax, Precirol ATO 5, and Compritol ATO 888, respectively. There was erosion in Stearic acid, but neither erosion nor swelling in Carnauba wax, was detected. According to the power law analysis, the diffusion mechanism was expressed as pure Fickian for Stearic acid and Carnauba wax and the coupling of Fickian and relaxation contributions for other Cutina HR, Beeswax, Compritol ATO 888, and Precirol ATO 5 tablets. It was found that Beeswax (kd=2.13) has a very close drug release rate with the target profile (kt=1.95). Our results suggested that swelling and relaxation properties of lipid matrices should be examined together for a correct evaluation on drug diffusion mechanism of insoluble matrices.

Exploiting Universality in Atoms with Large Scattering Lengths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braaten, Eric

2012-05-31

The focus of this research project was atoms with scattering lengths that are large compared to the range of their interactions and which therefore exhibit universal behavior at sufficiently low energies. Recent dramatic advances in cooling atoms and in manipulating their scattering lengths have made this phenomenon of practical importance for controlling ultracold atoms and molecules. This research project was aimed at developing a systematically improvable method for calculating few-body observables for atoms with large scattering lengths starting from the universal results as a first approximation. Significant progress towards this goal was made during the five years of the project.

Repulsive nature of optical potentials for high-energy heavy-ion scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furumoto, T.; Sakuragi, Y.; Yamamoto, Y.

2010-10-15

The recent works by the present authors predicted that the real part of heavy-ion optical potentials changes its character from attraction to repulsion around the incident energy per nucleon E/A=200-300 MeV on the basis of the complex G-matrix interaction and the double-folding model (DFM) and revealed that the three-body force plays an important role there. In the present paper, we have precisely analyzed the energy dependence of the calculated DFM potentials and its relation to the elastic-scattering angular distributions in detail in the case of the {sup 12}C+{sup 12}C system in the energy range of E/A=100-400 MeV. The tensor forcemore » contributes substantially to the energy dependence of the real part of the DFM potentials and plays an important role to lower the attractive-to-repulsive transition energy. The nearside and farside (N/F) decompositions of the elastic-scattering amplitudes clarify the close relation between the attractive-to-repulsive transition of the potentials and the characteristic evolution of the calculated angular distributions with the increase of the incident energy. Based on the present analysis, we propose experimental measurements for the predicted strong diffraction phenomena of the elastic-scattering angular distribution caused by the N/F interference around the attractive-to-repulsive transition energy together with the reduced diffractions below and above the transition energy.« less

Developmental toxicity study in Sprague-Dawley rats by whole-body exposure to N,N-diethylethanolamine vapor.

PubMed

Leung, H W; Murphy, S R

1998-01-01

Timed-pregnant Sprague-Dawley rats were exposed whole body to N,N-diethylethanolamine vapor for 6 h per day on gestational days (GD) 6-15 at targeted concentrations of 33, 66 or 100 ppm. Dams were sacrificed on GD 21. There was no maternal mortality in any exposed groups. Maternal toxicity observed in the 100 ppm group included dry rales, reduced body weight (9.5%) on GD 15 and reduced weight gain (48%) during exposure. Suppression of body weight gain was also noted in the 66 ppm group during GD 12-15. There were no effects of treatment on gestational parameters, including pre- and post-implantation loss or sex ratio. Mean fetal body weights in treated groups were comparable to controls. There was no increase in the incidence of total malformations (external, visceral or skeletal) or individually by category. The incidence of a single developmental variation (hypoplastic bones of the forepaw) in the 100 ppm groups was statistically significantly decreased relative to that of controls. The no-observed-adverse-effect level was 33 ppm for maternal toxicity but greater than 100 ppm for embryofetal toxicity and teratogenicity.

Extracting the σ-term from low-energy pion-nucleon scattering

NASA Astrophysics Data System (ADS)

Ruiz de Elvira, Jacobo; Hoferichter, Martin; Kubis, Bastian; Meißner, Ulf-G.

2018-02-01

We present an extraction of the pion-nucleon (π N) scattering lengths from low-energy π N scattering, by fitting a representation based on Roy-Steiner equations to the low-energy data base. We show that the resulting values confirm the scattering-length determination from pionic atoms, and discuss the stability of the fit results regarding electromagnetic corrections and experimental normalization uncertainties in detail. Our results provide further evidence for a large π N σ-term, {σ }π N=58(5) {{MeV}}, in agreement with, albeit less precise than, the determination from pionic atoms.

Diffuse X-ray scattering near a two-dimensional solid–liquid phase transition at the n-hexane–water interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tikhonov, A. M.

According to experimental data on X-ray scattering and reflectometry with synchrotron radiation, a twodimensional crystallization phase transition in a monolayer of melissic acid at the n-hexane–water interface with a decrease in the temperature occurs after a wetting transition.

Use of job-exposure matrices to estimate occupational exposure to pesticides: A review.

PubMed

Carles, Camille; Bouvier, Ghislaine; Lebailly, Pierre; Baldi, Isabelle

2017-03-01

The health effects of pesticides have been extensively studied in epidemiology, mainly in agricultural populations. However, pesticide exposure assessment remains a key methodological issue for epidemiological studies. Besides self-reported information, expert assessment or metrology, job-exposure matrices still appear to be an interesting tool. We reviewed all existing matrices assessing occupational exposure to pesticides in epidemiological studies and described the exposure parameters they included. We identified two types of matrices, (i) generic ones that are generally used in case-control studies and document broad categories of pesticides in a large range of jobs, and (ii) specific matrices, developed for use in agricultural cohorts, that generally provide exposure metrics at the active ingredient level. The various applications of these matrices in epidemiological studies have proven that they are valuable tools to assess pesticide exposure. Specific matrices are particularly promising for use in agricultural cohorts. However, results obtained with matrices have rarely been compared with those obtained with other tools. In addition, the external validity of the given estimates has not been adequately discussed. Yet, matrices would help in reducing misclassification and in quantifying cumulated exposures, to improve knowledge about the chronic health effects of pesticides.

n-body simulations using message passing parallel computers.

NASA Astrophysics Data System (ADS)

Grama, A. Y.; Kumar, V.; Sameh, A.

The authors present new parallel formulations of the Barnes-Hut method for n-body simulations on message passing computers. These parallel formulations partition the domain efficiently incurring minimal communication overhead. This is in contrast to existing schemes that are based on sorting a large number of keys or on the use of global data structures. The new formulations are augmented by alternate communication strategies which serve to minimize communication overhead. The impact of these communication strategies is experimentally studied. The authors report on experimental results obtained from an astrophysical simulation on an nCUBE2 parallel computer.

Solvers for $$\\mathcal{O} (N)$$ Electronic Structure in the Strong Scaling Limit

DOE PAGES

Bock, Nicolas; Challacombe, William M.; Kale, Laxmikant

2016-01-26

Here we present a hybrid OpenMP/Charm\\tt++ framework for solving themore » $$\\mathcal{O} (N)$$ self-consistent-field eigenvalue problem with parallelism in the strong scaling regime, $$P\\gg{N}$$, where $P$ is the number of cores, and $N$ is a measure of system size, i.e., the number of matrix rows/columns, basis functions, atoms, molecules, etc. This result is achieved with a nested approach to spectral projection and the sparse approximate matrix multiply [Bock and Challacombe, SIAM J. Sci. Comput., 35 (2013), pp. C72--C98], and involves a recursive, task-parallel algorithm, often employed by generalized $N$-Body solvers, to occlusion and culling of negligible products in the case of matrices with decay. Lastly, employing classic technologies associated with generalized $N$-Body solvers, including overdecomposition, recursive task parallelism, orderings that preserve locality, and persistence-based load balancing, we obtain scaling beyond hundreds of cores per molecule for small water clusters ([H$${}_2$$O]$${}_N$$, $$N \\in \\{ 30, 90, 150 \\}$$, $$P/N \\approx \\{ 819, 273, 164 \\}$$) and find support for an increasingly strong scalability with increasing system size $N$.« less

Sparse Matrices in MATLAB: Design and Implementation

NASA Technical Reports Server (NTRS)

Gilbert, John R.; Moler, Cleve; Schreiber, Robert

1992-01-01

The matrix computation language and environment MATLAB is extended to include sparse matrix storage and operations. The only change to the outward appearance of the MATLAB language is a pair of commands to create full or sparse matrices. Nearly all the operations of MATLAB now apply equally to full or sparse matrices, without any explicit action by the user. The sparse data structure represents a matrix in space proportional to the number of nonzero entries, and most of the operations compute sparse results in time proportional to the number of arithmetic operations on nonzeros.

Matrices of carbonaceous chondrite meteorites

NASA Technical Reports Server (NTRS)

Buseck, Peter R.; Hua, Xin

1993-01-01

The morphology, classification, and chemistry of the matrices of carbonaceous chondrite (CC) meteorites is reviewed based on recent research results. The various kinds of CCs are examined in terms of their matrix mineralogy. Alteration processes in CCs are discussed.

Truncated Linear Statistics Associated with the Eigenvalues of Random Matrices II. Partial Sums over Proper Time Delays for Chaotic Quantum Dots

NASA Astrophysics Data System (ADS)

Grabsch, Aurélien; Majumdar, Satya N.; Texier, Christophe

2017-06-01

Invariant ensembles of random matrices are characterized by the distribution of their eigenvalues \\{λ _1,\\ldots ,λ _N\\}. We study the distribution of truncated linear statistics of the form \\tilde{L}=\\sum _{i=1}^p f(λ _i) with p<N. This problem has been considered by us in a previous paper when the p eigenvalues are further constrained to be the largest ones (or the smallest). In this second paper we consider the same problem without this restriction which leads to a rather different analysis. We introduce a new ensemble which is related, but not equivalent, to the "thinned ensembles" introduced by Bohigas and Pato. This question is motivated by the study of partial sums of proper time delays in chaotic quantum dots, which are characteristic times of the scattering process. Using the Coulomb gas technique, we derive the large deviation function for \\tilde{L}. Large deviations of linear statistics L=\\sum _{i=1}^N f(λ _i) are usually dominated by the energy of the Coulomb gas, which scales as ˜ N^2, implying that the relative fluctuations are of order 1 / N. For the truncated linear statistics considered here, there is a whole region (including the typical fluctuations region), where the energy of the Coulomb gas is frozen and the large deviation function is purely controlled by an entropic effect. Because the entropy scales as ˜ N, the relative fluctuations are of order 1/√{N}. Our analysis relies on the mapping on a problem of p fictitious non-interacting fermions in N energy levels, which can exhibit both positive and negative effective (absolute) temperatures. We determine the large deviation function characterizing the distribution of the truncated linear statistics, and show that, for the case considered here (f(λ )=1/λ ), the corresponding phase diagram is separated in three different phases.

Agricultural matrices affect ground ant assemblage composition inside forest fragments

PubMed Central

Dos Santos, Iracenir Andrade; Ramos, Flavio Nunes; Majer, Jonathan David; Vilela, Evaldo Ferreira

2018-01-01

The establishment of agricultural matrices generally involves deforestation, which leads to fragmentation of the remaining forest. This fragmentation can affect forest dynamics both positively and negatively. Since most animal species are affected, certain groups can be used to measure the impact of such fragmentation. This study aimed to measure the impacts of agricultural crops (matrices) on ant communities of adjacent lower montane Atlantic rainforest fragments. We sampled nine forest fragments at locations surrounded by different agricultural matrices, namely: coffee (3 replicates); sugarcane (3); and pasture (3). At each site we installed pitfall traps along a 500 m transect from the interior of the matrix to the interior of the fragment (20 pitfall traps ~25 m apart). Each transect was partitioned into four categories: interior of the matrix; edge of the matrix; edge of the fragment; and interior of the fragment. For each sample site, we measured ant species richness and ant community composition within each transect category. Ant richness and composition differed between fragments and matrices. Each sample location had a specific composition of ants, probably because of the influence of the nature and management of the agricultural matrices. Species composition in the coffee matrix had the highest similarity to its corresponding fragment. The variability in species composition within forest fragments surrounded by pasture was greatest when compared with forest fragments surrounded by sugarcane or, to a lesser extent, coffee. Functional guild composition differed between locations, but the most representative guild was ‘generalist’ both in the agricultural matrices and forest fragments. Our results are important for understanding how agricultural matrices act on ant communities, and also, how these isolated forest fragments could act as an island of biodiversity in an ‘ocean of crops’. PMID:29791493

Agricultural matrices affect ground ant assemblage composition inside forest fragments.

PubMed

Assis, Diego Santana; Dos Santos, Iracenir Andrade; Ramos, Flavio Nunes; Barrios-Rojas, Katty Elena; Majer, Jonathan David; Vilela, Evaldo Ferreira

2018-01-01

The establishment of agricultural matrices generally involves deforestation, which leads to fragmentation of the remaining forest. This fragmentation can affect forest dynamics both positively and negatively. Since most animal species are affected, certain groups can be used to measure the impact of such fragmentation. This study aimed to measure the impacts of agricultural crops (matrices) on ant communities of adjacent lower montane Atlantic rainforest fragments. We sampled nine forest fragments at locations surrounded by different agricultural matrices, namely: coffee (3 replicates); sugarcane (3); and pasture (3). At each site we installed pitfall traps along a 500 m transect from the interior of the matrix to the interior of the fragment (20 pitfall traps ~25 m apart). Each transect was partitioned into four categories: interior of the matrix; edge of the matrix; edge of the fragment; and interior of the fragment. For each sample site, we measured ant species richness and ant community composition within each transect category. Ant richness and composition differed between fragments and matrices. Each sample location had a specific composition of ants, probably because of the influence of the nature and management of the agricultural matrices. Species composition in the coffee matrix had the highest similarity to its corresponding fragment. The variability in species composition within forest fragments surrounded by pasture was greatest when compared with forest fragments surrounded by sugarcane or, to a lesser extent, coffee. Functional guild composition differed between locations, but the most representative guild was 'generalist' both in the agricultural matrices and forest fragments. Our results are important for understanding how agricultural matrices act on ant communities, and also, how these isolated forest fragments could act as an island of biodiversity in an 'ocean of crops'.

Elastic properties of nc-TiN /a-Si3N4 and nc-TiN /a-BN nanocomposite films by surface Brillouin scattering

NASA Astrophysics Data System (ADS)

Manghnani, Murli H.; Tkachev, Sergey N.; Zinin, Pavel V.; Glorieoux, Christ; Karvankova, Pavla; Veprek, Stan

2005-03-01

The hardness of nanocomposite (nc) films developed recently appears to reach the hardness of diamond. High hardness is commonly attributed to the granular structure of nanocomposites (Hall-Petch effect) [E. O. Hall, Proc. Phys. Soc. Lond. B 64, 747 (1951); N. J. Petch, J. Iron Steel Inst. 174, 25 (1953)]. However, grain size in nanocomposites is generally small (5-15nm) and falls in the region where the Hall-Petch effect does not apply. The objective of the present study is to report the elastic properties of the superhard nanocomposites determined by means of surface Brillouin scattering (SBS), and to compare the results with those obtained by nanoindentation. Two types of nanocomposite films were studied: nc-TiN /a-Si3N4 and nc-TiN /a-BN. The SBS measurements presented yield values of Young's modulus significantly larger than those obtained from the slope of unloading indentation curve. This discrepancy is attributed to the lack of the validity of the assumptions behind the Sneddon's derivation of the formula used for the calculation of the Young's modulus from the indentation data.

MALDI matrices for low molecular weight compounds: an endless story?

PubMed

Calvano, Cosima Damiana; Monopoli, Antonio; Cataldi, Tommaso R I; Palmisano, Francesco

2018-04-23

Since its introduction in the 1980s, matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) has gained a prominent role in the analysis of high molecular weight biomolecules such as proteins, peptides, oligonucleotides, and polysaccharides. Its application to low molecular weight compounds has remained for long time challenging due to the spectral interferences produced by conventional organic matrices in the low m/z window. To overcome this problem, specific sample preparation such as analyte/matrix derivatization, addition of dopants, or sophisticated deposition technique especially useful for imaging experiments, have been proposed. Alternative approaches based on second generation (rationally designed) organic matrices, ionic liquids, and inorganic matrices, including metallic nanoparticles, have been the object of intense and continuous research efforts. Definite evidences are now provided that MALDI MS represents a powerful and invaluable analytical tool also for small molecules, including their quantification, thus opening new, exciting applications in metabolomics and imaging mass spectrometry. This review is intended to offer a concise critical overview of the most recent achievements about MALDI matrices capable of specifically address the challenging issue of small molecules analysis. Graphical abstract An ideal Book of matrices for MALDI MS of small molecules.

A new strategy on utilizing nitrogen doped TiO{sub 2} in nanostructured solar cells: Embedded multifunctional N-TiO{sub 2} scattering particles in mesoporous photoanode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shogh, Shiva; Mohammadpour, Raheleh; Iraji zad, Azam, E-mail: Iraji@sharif.edu

2015-12-15

Highlights: • N-doped TiO{sub 2} scattering particles were synthesized for embedding into commercial photoanode of dye sensitized solar cells. • Embedded scatterers improved optical and electrical features of the cells. • These multifunctional scatterers increased cell performance up to 17%. - Abstract: Aggregated sub-micron size nitrogen doped TiO{sub 2} (N-TiO{sub 2}) particles with superior optical and electrical features were successfully synthesized for embedding into commercial mesoporous TiO{sub 2} photoelectrode of dye sensitized solar cells (DSSCs) as the light scattering particles compared to undoped one. X-ray photoelectron spectroscopy and absorption spectra confirmed that the titanium dioxide is sufficiently doped by nitrogenmore » in N-TiO{sub 2} sample. Employing these high-surface N-TiO{sub 2} in mesoporous photoelectrode of solar cells, the power conversion efficiency of 8% has been achieved which shows 17% improvement for the optimum embedded level of doping (30 wt%) compared to commercial photoelectrode without additive; while enhanced efficiency is only 3% embedding undoped sub-micron size TiO{sub 2} particles. These results can introduce the novel multifunctional photoelectrode for nanostructured solar cells with enhanced values of scattering efficiency and improved electrical features including trap states density reduction in comparison to commercial mesoporous photoelectrodes.« less

The recurrence sequences via Sylvester matrices

NASA Astrophysics Data System (ADS)

Karaduman, Erdal; Deveci, Ömür

2017-07-01

In this work, we define the Pell-Jacobsthal-Slyvester sequence and the Jacobsthal-Pell-Slyvester sequence by using the Slyvester matrices which are obtained from the characteristic polynomials of the Pell and Jacobsthal sequences and then, we study the sequences defined modulo m. Also, we obtain the cyclic groups and the semigroups from the generating matrices of these sequences when read modulo m and then, we derive the relationships among the orders of the cyclic groups and the periods of the sequences. Furthermore, we redefine Pell-Jacobsthal-Slyvester sequence and the Jacobsthal-Pell-Slyvester sequence by means of the elements of the groups and then, we examine them in the finite groups.

Performance Properties of Graphite Reinforced Composites with Advanced Resin Matrices

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A.

1980-01-01

This article looks at the effect of different resin matrices on thermal and mechanical properties of graphite composites, and relates the thermal and flammability properties to the anaerobic char yield of the resins. The processing parameters of graphite composites utilizing graphite fabric and epoxy or other advanced resins as matrices are presented. Thermoset resin matrices studied were: aminecured polyfunctional glycidyl aminetype epoxy (baseline), phenolicnovolac resin based on condensation of dihydroxymethyl-xylene and phenol cured with hexamine, two types of polydismaleimide resins, phenolic resin, and benzyl resin. The thermoplastic matrices studied were polyethersulfone and polyphenylenesulfone. Properties evaluated in the study included anaerobic char yield, limiting oxygen index, smoke evolution, moisture absorption, and mechanical properties at elevated temperatures including tensile, compressive, and short-beam shear strengths. Generally, it was determined that graphite composites with the highest char yield exhibited optimum fire-resistant properties.

Eigenvalue statistics for the sum of two complex Wishart matrices

NASA Astrophysics Data System (ADS)

Kumar, Santosh

2014-09-01

The sum of independent Wishart matrices, taken from distributions with unequal covariance matrices, plays a crucial role in multivariate statistics, and has applications in the fields of quantitative finance and telecommunication. However, analytical results concerning the corresponding eigenvalue statistics have remained unavailable, even for the sum of two Wishart matrices. This can be attributed to the complicated and rotationally noninvariant nature of the matrix distribution that makes extracting the information about eigenvalues a nontrivial task. Using a generalization of the Harish-Chandra-Itzykson-Zuber integral, we find exact solution to this problem for the complex Wishart case when one of the covariance matrices is proportional to the identity matrix, while the other is arbitrary. We derive exact and compact expressions for the joint probability density and marginal density of eigenvalues. The analytical results are compared with numerical simulations and we find perfect agreement.

Brain connectome modularity in weight-restored anorexia nervosa and body dysmorphic disorder

PubMed Central

Zhang, A; Leow, A; Zhan, L; GadElkarim, J; Moody, T; Khalsa, S; Strober, M; Feusner, JD

2017-01-01

Background Anorexia nervosa (AN) and body dysmorphic disorder (BDD) frequently co-occur, and have several overlapping phenomenological features. Little is known about their shared neurobiology. Aims To compare modular organization of brain structural connectivity. Methods We acquired diffusion-weighted magnetic resonance imaging data on unmedicated individuals with BDD (n=29), weight-restored AN (n=24), and healthy controls (HC) (n=31). We constructed connectivity matrices using whole-brain white matter tractography, and compared modular structures across groups. Results AN showed abnormal modularity involving frontal, basal ganglia, and posterior cingulate nodes. There was a trend in BDD for similar abnormalities, but no significant differences compared with AN. In AN, poor insight correlated with longer path length in right caudal anterior cingulate and right posterior cingulate. Conclusions Abnormal network organization patterns in AN, partially shared with BDD, may have implications for understanding integration between reward and habit/ritual formation, as well as conflict monitoring/error detection. PMID:27429183

Variations of cosmic large-scale structure covariance matrices across parameter space

NASA Astrophysics Data System (ADS)

Reischke, Robert; Kiessling, Alina; Schäfer, Björn Malte

2017-03-01

The likelihood function for cosmological parameters, given by e.g. weak lensing shear measurements, depends on contributions to the covariance induced by the non-linear evolution of the cosmic web. As highly non-linear clustering to date has only been described by numerical N-body simulations in a reliable and sufficiently precise way, the necessary computational costs for estimating those covariances at different points in parameter space are tremendous. In this work, we describe the change of the matter covariance and the weak lensing covariance matrix as a function of cosmological parameters by constructing a suitable basis, where we model the contribution to the covariance from non-linear structure formation using Eulerian perturbation theory at third order. We show that our formalism is capable of dealing with large matrices and reproduces expected degeneracies and scaling with cosmological parameters in a reliable way. Comparing our analytical results to numerical simulations, we find that the method describes the variation of the covariance matrix found in the SUNGLASS weak lensing simulation pipeline within the errors at one-loop and tree-level for the spectrum and the trispectrum, respectively, for multipoles up to ℓ ≤ 1300. We show that it is possible to optimize the sampling of parameter space where numerical simulations should be carried out by minimizing interpolation errors and propose a corresponding method to distribute points in parameter space in an economical way.

Quantitative mass spectrometry of unconventional human biological matrices

NASA Astrophysics Data System (ADS)

Dutkiewicz, Ewelina P.; Urban, Pawel L.

2016-10-01

The development of sensitive and versatile mass spectrometric methodology has fuelled interest in the analysis of metabolites and drugs in unconventional biological specimens. Here, we discuss the analysis of eight human matrices-hair, nail, breath, saliva, tears, meibum, nasal mucus and skin excretions (including sweat)-by mass spectrometry (MS). The use of such specimens brings a number of advantages, the most important being non-invasive sampling, the limited risk of adulteration and the ability to obtain information that complements blood and urine tests. The most often studied matrices are hair, breath and saliva. This review primarily focuses on endogenous (e.g. potential biomarkers, hormones) and exogenous (e.g. drugs, environmental contaminants) small molecules. The majority of analytical methods used chromatographic separation prior to MS; however, such a hyphenated methodology greatly limits analytical throughput. On the other hand, the mass spectrometric methods that exclude chromatographic separation are fast but suffer from matrix interferences. To enable development of quantitative assays for unconventional matrices, it is desirable to standardize the protocols for the analysis of each specimen and create appropriate certified reference materials. Overcoming these challenges will make analysis of unconventional human biological matrices more common in a clinical setting. This article is part of the themed issue 'Quantitative mass spectrometry'.

Boundary reflection matrices for nonsimply laced affine Toda field theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, J.D.

The boundary reflection matrices for nonsimply laced affine Toda field theories defined on a half line with the Neumann boundary condition are investigated. The boundary reflection matrices for some pairs of the models are evaluated up to one loop order by perturbation theory. Then the exact boundary reflection matrices which are consistent with the one loop result are found under the assumption of {open_quote}{open_quote}duality{close_quote}{close_quote} and tested against algebraic consistency such as the boundary bootstrap equation and boundary crossing-unitarity relation. {copyright} {ital 1996 The American Physical Society.}

Small-Angle Scatter Measurement.

NASA Astrophysics Data System (ADS)

Wein, Steven Jay

effects of contaminants and surface defects. The model for the surface statistics is investigated. A K_0 (modified Bessel function) autocorrelation function is shown to predict the scattered light distribution of these samples much better than the conventional negative -exponential function. Additionally, a sampling theory is developed that addresses the negative-exponentially correlated output of lock-in amplifiers, detectors, and electronic circuits in general. It is shown that the optimum sampling rate is approximately one sample per time constant and at this rate the improvement in SNR is sqrt {N/2} where N is the number of measurements.

Boundary transfer matrices and boundary quantum KZ equations

NASA Astrophysics Data System (ADS)

Vlaar, Bart

2015-07-01

A simple relation between inhomogeneous transfer matrices and boundary quantum Knizhnik-Zamolodchikov (KZ) equations is exhibited for quantum integrable systems with reflecting boundary conditions, analogous to an observation by Gaudin for periodic systems. Thus, the boundary quantum KZ equations receive a new motivation. We also derive the commutativity of Sklyanin's boundary transfer matrices by merely imposing appropriate reflection equations, in particular without using the conditions of crossing symmetry and unitarity of the R-matrix.

When do star clusters become multiple star systems? II. Toward a half-life formalism with four bodies

NASA Astrophysics Data System (ADS)

Ibragimov, Timur; Leigh, Nathan W. C.; Ryu, Taeho; Panurach, Teresa; Perna, Rosalba

2018-03-01

We present a half-life formalism for describing the disruption of gravitationally-bound few-body systems, with a focus on binary-binary scattering. For negative total encounter energies, the four-body problem has three possible decay products in the point particle limit. For each decay product and a given set of initial conditions, we obtain directly from numerical scattering simulations the half-life for the distribution of disruption times. As in radioactive decay, the half-lives should provide a direct prediction for the relative fractions of each decay product. We test this prediction with simulated data and find good agreement with our hypothesis. We briefly discuss applications of this feature of the gravitational four-body problem to populations of black holes in globular clusters. This paper, the second in the series, builds on extending the remarkable similarity between gravitational chaos at the macroscopic scale and radioactive decay at the microscopic scale to larger-N systems.

When do star clusters become multiple star systems? II. Towards a half-life formalism with four bodies

NASA Astrophysics Data System (ADS)

Ibragimov, Timur; Leigh, Nathan W. C.; Ryu, Taeho; Panurach, Teresa; Perna, Rosalba

2018-07-01

We present a half-life formalism for describing the disruption of gravitationally bound few-body systems, with a focus on binary-binary scattering. For negative total encounter energies, the four-body problem has three possible decay products in the point-particle limit. For each decay product and a given set of initial conditions, we obtain directly from numerical scattering simulations the half-life for the distribution of disruption times. As in radioactive decay, the half-lives should provide a direct prediction for the relative fractions of each decay product. We test this prediction with simulated data and find good agreement with our hypothesis. We briefly discuss applications of this feature of the gravitational four-body problem to populations of black holes in globular clusters. This paper, the second in the series, builds on extending the remarkable similarity between gravitational chaos at the macroscopic scale and radioactive decay at the microscopic scale to larger-N systems.

Analysing generator matrices G of similar state but varying minimum determinants

NASA Astrophysics Data System (ADS)

Harun, H.; Razali, M. F.; Rahman, N. A. Abdul

2016-10-01

Since Tarokh discovered Space-Time Trellis Code (STTC) in 1998, a considerable effort has been done to improve the performance of the original STTC. One way of achieving enhancement is by focusing on the generator matrix G, which represents the encoder structure for STTC. Until now, researchers have only concentrated on STTCs of different states in analyzing the performance of generator matrix G. No effort has been made on different generator matrices G of similar state. The reason being, it is difficult to produce a wide variety of generator matrices G with diverse minimum determinants. In this paper a number of generator matrices G with minimum determinant of four (4), eight (8) and sixteen (16) of the same state (i.e., 4-PSK) have been successfully produced. The performance of different generator matrices G in term of their bit error rate and signal-to-noise ratio for a Rayleigh fading environment are compared and evaluated. It is found from the MATLAB simulation that at low SNR (<8), the BER of generator matrices G with smaller minimum determinant is comparatively lower than those of higher minimum determinant. However, at high SNR (>14) there is no significant difference between the BER of these generator matrices G.

Computing partial traces and reduced density matrices

NASA Astrophysics Data System (ADS)

Maziero, Jonas

Taking partial traces (PTrs) for computing reduced density matrices, or related functions, is a ubiquitous procedure in the quantum mechanics of composite systems. In this paper, we present a thorough description of this function and analyze the number of elementary operations (ops) needed, under some possible alternative implementations, to compute it on a classical computer. As we note, it is worthwhile doing some analytical developments in order to avoid making null multiplications and sums, what can considerably reduce the ops. For instance, for a bipartite system ℋa⊗ℋb with dimensions da=dimℋa and db=dimℋb and for da,db≫1, while a direct use of PTr definition applied to ℋb requires 𝒪(da6db6) ops, its optimized implementation entails 𝒪(da2db) ops. In the sequence, we regard the computation of PTrs for general multipartite systems and describe Fortran code provided to implement it numerically. We also consider the calculation of reduced density matrices via Bloch’s parametrization with generalized Gell Mann’s matrices.

The Shortened Raven Standard Progressive Matrices: Item Response Theory-Based Psychometric Analyses and Normative Data

ERIC Educational Resources Information Center

Van der Elst, Wim; Ouwehand, Carolijn; van Rijn, Peter; Lee, Nikki; Van Boxtel, Martin; Jolles, Jelle

2013-01-01

The purpose of the present study was to evaluate the psychometric properties of a shortened version of the Raven Standard Progressive Matrices (SPM) under an item response theory framework (the one- and two-parameter logistic models). The shortened Raven SPM was administered to N = 453 cognitively healthy adults aged between 24 and 83 years. The…

Component Identification and Item Difficulty of Raven's Matrices Items.

ERIC Educational Resources Information Center

Green, Kathy E.; Kluever, Raymond C.

Item components that might contribute to the difficulty of items on the Raven Colored Progressive Matrices (CPM) and the Standard Progressive Matrices (SPM) were studied. Subjects providing responses to CPM items were 269 children aged 2 years 9 months to 11 years 8 months, most of whom were referred for testing as potentially gifted. A second…

Strategy use fully mediates the relationship between working memory capacity and performance on Raven's matrices.

PubMed

Gonthier, Corentin; Thomassin, Noémylle

2015-10-01

Working memory capacity consistently correlates with fluid intelligence. It has been suggested that this relationship is partly attributable to strategy use: Participants with high working memory capacity would use more effective strategies, in turn leading to higher performance on fluid intelligence tasks. However, this idea has never been directly investigated. In 2 experiments, we tested this hypothesis by directly manipulating strategy use in a combined experimental-correlational approach (Experiment 1; N = 250) and by measuring strategy use with a self-report questionnaire (Experiment 2; N = 93). Inducing all participants to use an effective strategy in Raven's matrices decreased the correlation between working memory capacity and performance; the strategy use measure fully mediated the relationship between working memory capacity and performance on the matrices task. These findings indicate that individual differences in strategic behavior drive the predictive utility of working memory. We interpret the results within a theoretical framework integrating the multiple mediators of the relationship between working memory capacity and high-level cognition. (c) 2015 APA, all rights reserved).

Alternative CHCA-based matrices for the analysis of low molecular weight compounds by UV-MALDI-tandem mass spectrometry.

PubMed

Porta, Tiffany; Grivet, Chantal; Knochenmuss, Richard; Varesio, Emmanuel; Hopfgartner, Gérard

2011-02-01

Analysis of low molecular weight compounds (LMWC) in complex matrices by vacuum matrix-assisted laser desorption/ionization (MALDI) often suffers from matrix interferences, which can severely degrade limits of quantitation. It is, therefore, useful to have available a range of suitable matrices, which exhibit complementary regions of interference. Two newly synthesized α-cyanocinnamic acid derivatives are reported here; (E)-2-cyano-3-(naphthalen-2-yl)acrylic acid (NpCCA) and (2E)-3-(anthracen-9-yl)-2-cyanoprop-2enoic acid (AnCCA). Along with the commonly used α-cyano-4-hydroxycinnamic acid (CHCA), and the recently developed 4-chloro-α-cyanocinnamic acid (Cl-CCA) matrices, these constitute a chemically similar series of matrices covering a range of molecular weights, and with correspondingly differing ranges of spectral interference. Their performance was compared by measuring the signal-to-noise ratios (S/N) of 47 analytes, mostly pharmaceuticals, with the different matrices using the selected reaction monitoring (SRM) mode on a triple quadrupole instrument equipped with a vacuum MALDI source. AnCCA, NpCCA and Cl-CCA were found to offer better signal-to-noise ratios in SRM mode than CHCA, but Cl-CCA yielded the best results for 60% of the compounds tested. To better understand the relative performance of this matrix series, the proton affinities (PAs) were measured using the kinetic method. Their relative values were: AnCCA > CHCA > NpCCA > Cl-CCA. This ordering is consistent with the performance data. The synthesis of the new matrices is straightforward and they provide (1) tunability of matrix background interfering ions and (2) enhanced analyte response for certain classes of compounds. Copyright © 2011 John Wiley & Sons, Ltd.

Use of the Wigner representation in scattering problems

NASA Technical Reports Server (NTRS)

Bemler, E. A.

1975-01-01

The basic equations of quantum scattering were translated into the Wigner representation, putting quantum mechanics in the form of a stochastic process in phase space, with real valued probability distributions and source functions. The interpretative picture associated with this representation is developed and stressed and results used in applications published elsewhere are derived. The form of the integral equation for scattering as well as its multiple scattering expansion in this representation are derived. Quantum corrections to classical propagators are briefly discussed. The basic approximation used in the Monte-Carlo method is derived in a fashion which allows for future refinement and which includes bound state production. Finally, as a simple illustration of some of the formalism, scattering is treated by a bound two body problem. Simple expressions for single and double scattering contributions to total and differential cross-sections as well as for all necessary shadow corrections are obtained.

Wave Scattering in Heterogeneous Media using the Finite Element Method

DTIC Science & Technology

2016-10-21

AFRL-AFOSR-JP-TR-2016-0086 Wave Scattering in Heterogeneous Media using the Finite Element Method Chiruvai Vendhan INDIAN INSTITUTE OF TECHNOLOGY...Scattering in Heterogeneous Media using the Finite Element Method 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-12-1-4026 5c.  PROGRAM ELEMENT NUMBER 61102F 6...14.  ABSTRACT The primary aim of this study is to develop a finite element model for elastic scattering by axisymmetric bodies submerged in a

Scatter characterization and correction for simultaneous multiple small-animal PET imaging.

PubMed

Prasad, Rameshwar; Zaidi, Habib

2014-04-01

ranged between 25 and 64% when imaging multiple subjects (three to five) of different size simultaneously in comparison to imaging a single subject. The spill-over ratio (SOR) increases with increasing the number of subjects in the FOV. Scatter correction improved the SOR for both water and air cold compartments of single and multiple imaging studies. The recovery coefficients for different body parts of the mouse whole-body and rat whole-body anatomical models were improved for multiple imaging studies following scatter correction. The magnitude and spatial distribution of the scatter component in small-animal PET imaging of single and multiple subjects simultaneously were characterized, and its impact was evaluated in different situations. Scatter correction improves PET image quality and quantitative accuracy for single rat and simultaneous multiple mice and rat imaging studies, whereas its impact is insignificant in single mouse imaging.