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1

Extension of RAPTOR-M3G to r-?-z Geometry for Use in Reactor Dosimetry Applications  

NASA Astrophysics Data System (ADS)

The RAPTOR-M3G (RApid Parallel Transport Of Radiation - Multiple 3-D Geometries) is a new deterministic radiation transport code that was originally developed for x-y-z geometry. The development of the r-?-z version of RAPTOR-M3G and its application to determine ex-vessel neutron dosimetry responses in the cavity of a typical 2-loop pressurized water reactor is presented. The neutron dosimetry responses determined from RAPTOR-M3G and TORT 3-D r-?-z calculations are compared to actual measured responses.

Hunter, Melissa A.; Longoni, Gianluca; Anderson, Stanwood L.

2009-08-01

2

GBL-2D Version 1.0: a 2D geometry boolean library.  

SciTech Connect

This report describes version 1.0 of GBL-2D, a geometric Boolean library for 2D objects. The library is written in C++ and consists of a set of classes and routines. The classes primarily represent geometric data and relationships. Classes are provided for 2D points, lines, arcs, edge uses, loops, surfaces and mask sets. The routines contain algorithms for geometric Boolean operations and utility functions. Routines are provided that incorporate the Boolean operations: Union(OR), XOR, Intersection and Difference. A variety of additional analytical geometry routines and routines for importing and exporting the data in various file formats are also provided. The GBL-2D library was originally developed as a geometric modeling engine for use with a separate software tool, called SummitView [1], that manipulates the 2D mask sets created by designers of Micro-Electro-Mechanical Systems (MEMS). However, many other practical applications for this type of software can be envisioned because the need to perform 2D Boolean operations can arise in many contexts.

McBride, Cory L. (Elemental Technologies, American Fort, UT); Schmidt, Rodney Cannon; Yarberry, Victor R.; Meyers, Ray J. (Elemental Technologies, American Fort, UT)

2006-11-01

3

Collective motion of squirmers in a quasi-2D geometry  

NASA Astrophysics Data System (ADS)

Microorganisms like bacteria, algae or spermatozoa typically move in an aqueous environment where they interact via hydrodynamic flow fields. Recent experiments studied the collective motion of dense suspensions of bacteria where swarming and large-scale turbulence emerged. Moreover, spherical artificial microswimmers, so-called squirmers, have been constructed and studied in a quasi-2D geometry. Here we present a numerical study of the collective dynamics of squirmers confined in quasi-2D between two parallel walls. Because of their spherical shape the reorientation of squirmers is solely due to noise and hydrodynamic interactions via induced flow fields. This is in contrast to elongated swimmers like bacteria which locally align due to steric interactions. We study the collective motion of pushers, pullers and potential swimmers at different densities. At small densities the squirmers are oriented parallel to the walls and pairwise collisions determine the reorientation rate. In dense suspensions rotational diffusion is greatly enhanced and pushers, in particular, tend to orient perpendicular to the walls. This effects the dynamics of the emerging clusters. In very dense suspensions we observe active jamming and long-lived crystalline structures.

ZöTtl, Andreas; Stark, Holger

2013-03-01

4

GBL-2D Version 1.0: A 2D Geometry Boolean Library.  

National Technical Information Service (NTIS)

This report describes version 1.0 of GBL-2D, a geometric Boolean library for 2D objects. The library is written in C++ and consists of a set of classes and routines. The classes primarily represent geometric data and relationships. Classes are provided fo...

C. L. McBride V. Yarbeery R. C. Schmidt R. J. Meyers

2006-01-01

5

Cloaking of 2D particle geometries in a surface medium  

NASA Astrophysics Data System (ADS)

We theoretically examine the cloaking condition for two-dimensional particles with varying geometry embedded inside a surface medium. General solutions are obtained for multi-layer particle configurations with either all positive or partially negative constitutive parameters respectively. Cloaking of particle geometries that are large relative to the incident wavelength is demonstrated. Theoretical predictions are compared to full-wave numerical simulations for arrays of particles consisting of different geometries.

Alexopoulos, A.; Yau, K. S. B.

2013-06-01

6

Simulation of viscous 2D-planar cylindrical geometry deformation using DR-BEM  

Microsoft Academic Search

In this paper, a novel boundary element formulation for the deformation of a viscous 2D-planar cylindrical geometry, immersed in a different viscous fluid and moving towards a rigid wall, is proposed for moderate Reynolds number, considering surface tension effects. The boundary integral formulation for Stokes flow inside and outside the geometry is represented in terms of a combined distribution of

J. P. Hernandez; T. A. Osswald; D. A. Weiss

2003-01-01

7

Radiation transport calculation in high enthalpy environments for 2D-axisymmetric geometries  

SciTech Connect

The radiative source terms and boundary heat fluxes for generic, 2D-axisymmetric geometries are presently obtained via a Monte Carlo method whose geometrical discretization employs curvilinear structured grids. Attention is given to both the spectral behavior of gas radiation and the thermochemical nonequilibrium conditions of the medium, using the NEQAIR data base. The radiation-simulation method proceeds from a given flowfield solution for the given geometry; the radiative source terms are obtained in a form that is adequate for coupling with the flowfield energy equations. 20 refs.

Gogel, T.H.; Dupuis, M.; Messerschmid, E.W. (Stuttgart Univ. (Germany))

1993-01-01

8

Radiation transport calculation in high enthalpy environments for 2D-axisymmetric geometries  

NASA Astrophysics Data System (ADS)

The radiative source terms and boundary heat fluxes for generic, 2D-axisymmetric geometries are presently obtained via a Monte Carlo method whose geometrical discretization employs curvilinear structured grids. Attention is given to both the spectral behavior of gas radiation and the thermochemical nonequilibrium conditions of the medium, using the NEQAIR data base. The radiation-simulation method proceeds from a given flowfield solution for the given geometry; the radiative source terms are obtained in a form that is adequate for coupling with the flowfield energy equations.

Gogel, T. H.; Dupuis, M.; Messerschmid, E. W.

1993-07-01

9

Radiation transport calculation in high enthalpy environments for 2D-axisymmetric geometries  

Microsoft Academic Search

The radiative source terms and boundary heat fluxes for generic, 2D-axisymmetric geometries are presently obtained via a Monte Carlo method whose geometrical discretization employs curvilinear structured grids. Attention is given to both the spectral behavior of gas radiation and the thermochemical nonequilibrium conditions of the medium, using the NEQAIR data base. The radiation-simulation method proceeds from a given flowfield solution

T. H. Gogel; M. Dupuis; E. W. Messerschmid

1993-01-01

10

Ultracold dipolar collisions of KRb molecules in a 2D confined geometry  

NASA Astrophysics Data System (ADS)

Ultracold fermionic polar molecules of ^40K^87Rb in their absolute rovibronic and hyperfine ground state [1] have been recently created and pave the way to probe ultracold chemistry of polar molecules [2]. When an electric field is applied, KRb + KRb -> K2 + Rb2 chemical rates increase as the sixth power of the molecule induced dipole moment [3], due dominantly to head-to-tail collisions. As a consequence, chemical reactions are enhanced in an electric field and are unfavorable to long lifetimes of polar molecules. To prevent these collisions, an additional optical lattice can be used to confine the molecules in two dimensions. In this talk, we will present a theoretical investigation of ultracold dipolar collisions of indistinguishable KRb molecules in a presence of an electric field in a 2D confined geometry. We will present expected chemical rates as a function of the electric field and discuss if this will be favorable to achieve evaporative cooling of a dense sample of KRb molecules. [1] Ni et al., Science 322, 231 (2008) ; Ospelkaus et al., Phys. Rev. Lett. 104, 030402 (2010). [2] Ospelkaus et al., arXiv:0912.3854, Science, in press (2010). [3] Qu'em'ener et al., Phys. Rev. A, in press (2010) ; Ni et al., arXiv:1001.2809, submitted (2010).

Quemener, Goulven; Bohn, John

2010-03-01

11

A 2-D Floquet boundary condition for time-domain finite element analysis of periodic geometries  

Microsoft Academic Search

In this paper, we outline a derivation for an absorbing boundary condition (ABC) that, when used with a recently developed FEM-TD formulation, is capable of effectively truncating the computational domain due to higher-order Floquet modes for electromagnetic simulations of infinite periodic structures in 2D. We demonstrated the accuracy of the new ABC, as well as indicating that the inclusion of

L. E. R. Petersson; Zheng Lou; Jian-Ming An

2005-01-01

12

Fully Determined Fluid Velocity Fields for 2D Materials with Complex Geometries.  

NASA Astrophysics Data System (ADS)

The movement of fluid in geological structures is crucial to many geologic processes, yet we remain unable to accurately model transport in realistically complex media in either 2 or 3 dimensions. The essence of the problem is the scale invariance of natural materials, whose geometry directly governs fluid movement and makes the prediction of fluid velocities in realistic situations difficult. At present, discrete modelling techniques such as the Lattice Boltzmann scheme, offer the greatest potential for numerically simulating fluid flow in such geometries. A lack of accurate empirical data for flow through complex geometries, however, means that existing models can only be tested for simple scenarios and, as a consequence, are reliant on the assumption that the models accurately predict flow in the geometries of interest. In response to this, an experimental technique has been developed to measure high-resolution velocity fields in complex media. The media are created by numerically constructing a fractally correlated porous matrices and superimposing them with fractal fracture sets. A modified Lattice Boltzmann scheme can then be used to simulate the fluid velocity field through this numeric model. The experimental technique is based on the translation of this complex medium geometry into a physical model, or flow cell, capable of conducting fluid. To produce the flow cell, the Boolean digital map of the solid and void space in the medium is rendered in plastic using stereolithography. This technique produces a precise copy of the medium in a layer 200x200x2mm, held between 2 transparent plates. The flow cell is then enclosed in a purpose built rig that permits controlled fluid flow and direct observation of the fluid behaviour. The fluid is seeded with 0.01mm neutrally buoyant particles and the velocity of the fluid in 0.5mm interrogation areas is determined using high-resolution digital particle imaging velocimetry. Systematic analysis of all porous subareas using both cross-correlation and streak analysis techniques allows a complete, high-resolution velocity field to be mapped. This measured velocity field is then compared directly with the predicted velocity field, and the accuracy of the numeric scheme evaluated.

Cassidy, R.; McCloskey, J.; Morrow, P.

2001-12-01

13

Determining Transition State Geometries in Liquids Using 2D-IR  

SciTech Connect

Many properties of chemical reactions are determined by the transition state connecting reactant and product, yet it is difficult to directly obtain any information about these short-lived structures in liquids. We show that two-dimensional infrared (2D-IR) spectroscopy can provide direct information about transition states by tracking the transformation of vibrational modes as a molecule crossed a transition state. We successfully monitored a simple chemical reaction, the fluxional rearrangement of Fe(CO)5, in which the exchange of axial and equatorial CO ligands causes an exchange of vibrational energy between the normal modes of the molecule. This energy transfer provides direct evidence regarding the time scale, transition state, and mechanism of the reaction.

Harris, Charles; Cahoon, James F.; Sawyer, Karma R.; Schlegel, Jacob P.; Harris, Charles B.

2007-12-11

14

Manipulation of 3D Cluster Size and Geometry by Release from 2D Micropatterns  

PubMed Central

A novel method to control three-dimensional cell cluster size and geometry using two-dimensional patterning techniques is described. Cells were first cultured on two-dimensional micropatterned collagen using conventional soft lithography techniques. Collagenase was used to degrade the micropatterned collagen and release cells from the micropatterns, forming clusters of cells which were then resuspended in a three-dimensional collagen matrix. This method facilitated the formation of uniformly sized clusters within a single sample. By systematically varying the geometry of the two-dimensional micropatterned islands, final cluster size and cell number in three dimensions could be controlled. Using this technique, we showed that proliferation of cells within collagen gels depended on the size of clusters, suggesting an important role for multicellular structure on biological function. Furthermore, by utilizing more complex two-dimensional patterns, non-spherical structures could be produced. This technique demonstrates a simple way to exploit two-dimensional micro-patterning in order to create complex and structured multicellular clusters in a three-dimensional environment.

Leight, Jennifer L.; Liu, Wendy F.; Chaturvedi, Ritika R.; Chen, Sophia; Yang, Michael T.; Raghavan, Srivatsan; Chen, Christopher S.

2013-01-01

15

A numerical study on the thermal initiation of a confined explosive in 2-D geometry.  

PubMed

Insensitive munitions design against thermal stimuli like slow or fast cook-off has become a significant requirement for today's munitions. In order to achieve insensitive munitions characteristics, the response of the energetic material needs to be predicted against heating stimuli. In this study, a 2D numerical code was developed to simulate the slow and fast cook-off heating conditions of confined munitions and to obtain the response of the energetic materials. Computations were performed in order to predict the transient temperature distribution, the ignition time, and the location of ignition in the munitions. These predictions enable the designers to have an idea of when and at which location the energetic material ignites under certain adverse surrounding conditions. In the paper, the development of the code is explained and the numerical results are compared with available experimental and numerical data in the literature. Additionally, a parametric study was performed showing the effect of dimensional scaling of munitions and the heating rate on the ignition characteristics. PMID:21130568

Aydemir, Erdo?an; Ulas, Abdullah

2010-11-12

16

Investigation of 2D Transient Heat Transfer under the Effect of Dual-Phase-Lag Model in a Nanoscale Geometry  

NASA Astrophysics Data System (ADS)

Analytical and numerical solutions of the 2D transient dual-phase-lag (DPL) heat conduction equation are presented in this article. The geometry is that of a simplified metal oxide semiconductor field effect transistor with a heater placed on it. A temperature jump boundary condition is used on all boundaries in order to consider boundary phonon scattering at the micro- and nanoscale. A combination of a Laplace transformation technique and separation of variables is used to solve governing equations analytically, and a three-level finite difference scheme is employed to generate numerical results. The results are illustrated for three Knudsen numbers of 0.1, 1, and 10 at different instants of time. It is seen that the wave characteristic of the DPL model is strengthened by increasing the Knudsen number. It is found that the combination of the DPL model with the proposed mixed-type temperature boundary condition has the potential to accurately predict a 2D temperature distribution not only within the transistor itself but also in the near-boundary region.

Ghazanfarian, J.; Abbassi, A.

2012-03-01

17

Spontaneous wrinkling in azlactone-based functional polymer thin films in 2D and 3D geometries for guided nanopatterning  

SciTech Connect

We report a simple, one step process for developing wrinkling patterns in azlactone-based polymer thin films and brushes in 2D and 3D surfaces. The polymer used in this work wrinkles spontaneously upon deposition and solidification on a substrate without applying any external strain to the substrate, with the mode of deposition defining the direction of the wrinkles. Wrinkle formation is shown to occur on a variety of substrates over large areas. We also find that a very thin brush-like layer of an azlactone-containing block copolymer also exhibits wrinkled topology. Given the spontaneity and versatility of wrinkle formation, we further demonstrate two proofs-of-concept, i) that these periodic wrinkled structures are not limited to planar surfaces, but are also developed in complex geometries including tubes, cones and other 3D structures; and ii) that this one-step wrinkling process can be used to guide the deposition of metal nanoparticles and quantum dots, creating a periodic, nanopatterned film.

Ramanathan, Nathan Muruganathan [ORNL; Lokitz, Bradley S [ORNL; Messman, Jamie M [ORNL; Stafford, Christopher M [National Institute of Standards and Technology (NIST); Kilbey, II, S Michael [ORNL

2013-01-01

18

Detailed Characterization of 2D and 3D Scatter-to-Primary Ratios of Various Breast Geometries Using a Dedicated CT Mammotomography System  

PubMed Central

With a dedicated breast CT system using a quasi-monochromatic x-ray source and flat-panel digital detector, the 2D and 3D scatter to primary ratios (SPR) of various geometric phantoms having different densities were characterized in detail. Projections were acquired using geometric and anthropomorphic breast phantoms. Each phantom was filled with 700ml of 5 different water-methanol concentrations to simulate effective boundary densities of breast compositions from 100% glandular (1.0g/cm3) to 100% fat (0.79g/cm3). Projections were acquired with and without a beam stop array. For each projection, 2D scatter was determined by cubic spline interpolating the values behind the shadow of each beam stop through the object. Scatter-corrected projections were obtained by subtracting the scatter, and the 2D SPRs were obtained as a ratio of the scatter to scatter-corrected projections. Additionally the (un)corrected data were individually iteratively reconstructed. The (un)corrected 3D volumes were subsequently subtracted, and the 3D SPRs obtained from the ratio of the scatter volume-to-scatter-corrected (or primary) volume. Results show that the 2D SPR values peak in the center of the volumes, and were overall highest for the simulated 100% glandular composition. Consequently, scatter corrected reconstructions have visibly reduced cupping regardless of the phantom geometry, as well as more accurate linear attenuation coefficients. The corresponding 3D SPRs have increased central density, which reduces radially. Not surprisingly, for both 2D and 3D SPRs there was a dependency on both phantom geometry and object density on the measured SPR values, with geometry dominating for 3D SPRs. Overall, these results indicate the need for scatter correction given different geometries and breast densities that will be encountered with 3D cone beam breast CT.

Shah, Jainil; Pachon, Jan H.; Madhav, Priti; Tornai, Martin P.

2012-01-01

19

Feasibility study on the hybrid soft x-ray diagnostics with tomography and tangential 2-D array in toroidal geometry  

NASA Astrophysics Data System (ADS)

A hybrid diagnostic method based on the tangentially as well as poloidally arranged soft x-ray array detectors is studied to obtain toroidally-localized information of the plasma activity. Toroidally-localized MHD mode structure can be acquired by comparing the 2-D cross-sectional image by tomography with inverted 2-D slices from the tangentially-integrated 2-D imaging result and the toroidal weight matrix without using toroidally-separated arrays and magnetic diagnostics. Several MHD phantoms were chosen for the test to extract toroidal properties of the plasma. Tomographic reconstruction and 2-D mapping of the image from the tangential array are based on the bayesian pixon method and matrix operation. The pixon method, which allows the model parameter such as pixel size to change according to the information contained in each pixel, can reconstruct the image near the edge pedestal of the D-shaped plasma and sheared plasma profile. This hybrid method can be applied to identification of toroidal mode structure and toroidal component of impurity transport with soft x-ray imaging systems.

Kim, Junghee; Choe, W.

2004-11-01

20

From on-line sketching to 2D and 3D geometry: a system based on fuzzy knowledge  

Microsoft Academic Search

The paper describes the development of a fuzzy knowledge-based prototype system for conceptual design. This real time system is designed to infer user's sketching intentions, to segment sketched input and generate corresponding geometric primitives: straight lines, circles; arcs, ellipses, elliptical arcs, and B-spline curves. Topology information (connectivity, unitary constraints and pairwise constraints) is received dynamically from 2D sketched input and

Sheng Feng Qin; David K. Wright; Ivan N. Jordanov

2000-01-01

21

The influence of step geometry on the desorption characteristics of O2, D2, and H2O from stepped Pt surfaces  

NASA Astrophysics Data System (ADS)

We have compared the desorption characteristics of O2, D2, and H2O from the Pt(533) surface to the Pt(553) surface using temperature programmed desorption. Both surfaces consist of four atom wide (111) terraces interrupted by monoatomic steps of the different step geometries: (100) versus (110), respectively. We find that desorption is influenced significantly by the presence of step sites and the geometry of those sites. In general, molecules and atoms are thought to be bound more strongly to step sites than to terrace sites. Our D2 desorption data from Pt(553) provide an anomalous counterexample to this common belief since D atoms on this surface appear to be bound stronger by terrace sites. We also show that it is not possible to say a priori which step geometry will bind atoms or molecules stronger: recombinatively desorbing O atoms are bound stronger to (100) sites, whereas H2O molecules are bound stronger to (110) sites. Furthermore, the amount of adatoms or molecules that are affected by the presence of steps varies for the different species, as is evident from the various step: terrace ratios of ~1:1.3 for O2 (O), ~1:3 for D2 (D), and ~1:1 for H2O. This indicates that, in contrast to deuterium, more oxygen atoms and water molecules are affected by the presence of steps than would be expected on geometrical arguments alone.

van der Niet, Maria J. T. C.; den Dunnen, Angela; Juurlink, Ludo B. F.; Koper, Marc T. M.

2010-05-01

22

A Piecewise Linear Discontinuous Finite Element Spatial Discretization of the Transport Equation in 2D Cylindrical Geometry  

SciTech Connect

We present a new spatial discretization of the discrete-ordinates transport equation in two-dimensional cylindrical (RZ) geometry for arbitrary polygonal meshes. This discretization is a discontinuous finite element method that utilizes the piecewise linear basis functions developed by Stone and Adams. We describe an asymptotic analysis that shows this method to be accurate for many problems in the thick diffusion limit on arbitrary polygons, allowing this method to be applied to radiative transfer problems with these types of meshes. We also present numerical results for multiple problems on quadrilateral grids and compare these results to the well-known bi-linear discontinuous finite element method.

Bailey, T S; Adams, M L; Chang, J H

2008-10-01

23

Numerical Solution of the Boundary Problem for 2D Laplace Equation for Electrostatic Potential in Given Geometry  

NASA Astrophysics Data System (ADS)

This work has been performed as a student project for the upper division Electricity & Magnetism course. The objective was to numerically model the potential grid and the electric field of 2-dimensional capacitors of various geometries and compare them to the experimental data. This has been accomplished by the implementation of finite difference Gauss-Seidel iteration method through the use of the C programming language. Numeric results were then compared to experimental data. The expectations for this project were to successfully simulate the mapping of the experimental potential grid and electric field through the program code. The final results were satisfying since they closely resemble measured potentials.

Land, Jared; Land, Jeremy; Khan, Sheharyar

2012-03-01

24

2-D reconstruction of atmospheric concentration peaks from horizontal long path DOAS tomographic measurements: parametrisation and geometry within a discrete approach  

NASA Astrophysics Data System (ADS)

In this study, we theoretically investigate the reconstruction of 2-D cross sections through Gaussian concentration distributions, e.g. emission plumes, from long path DOAS measurements along a limited number of light paths. This is done systematically with respect to the extension of the up to four peaks and for six different measurement setups with 2-4 telescopes and 36 light paths each. We distinguish between cases with and without additional background concentrations. Our approach parametrises the unknown distribution by local piecewise constant or linear functions on a regular grid and solves the resulting discrete, linear system by a least squares minimum norm principle. We show that the linear parametrisation not only allows better representation of the distributions in terms of discretisation errors, but also better inversion of the system. We calculate area integrals of the concentration field (i.e. total emissions rates for non-vanishing perpendicular wind speed components) and show that reconstruction errors and reconstructed area integrals within the peaks for narrow distributions crucially depend on the resolution of the reconstruction grid. A recently suggested grid translation method for the piecewise constant basis functions, combining reconstructions from several shifted grids, is modified for the linear basis functions and proven to reduce overall reconstruction errors, but not the uncertainty of concentration integrals. We suggest a procedure to subtract additional background concentration fields before inversion. We find large differences in reconstruction quality between the geometries and conclude that, in general, for a constant number of light paths increasing the number of telescopes leads to better reconstruction results. It appears that geometries that give better results for negligible measurement errors and parts of the geometry that are better resolved are also less sensitive to increasing measurement errors.

Hartl, A.; Song, B. C.; Pundt, I.

2006-03-01

25

2-D reconstruction of atmospheric concentration peaks from horizontal long path DOAS tomographic measurements: parametrisation and geometry within a discrete approach  

NASA Astrophysics Data System (ADS)

In this study, we theoretically investigate the reconstruction of 2-D cross sections through Gaussian concentration distributions, e.g. emission plumes, from long path DOAS measurements along a limited number of light paths. This is done systematically with respect to the extension of the up to four peaks and for six different measurement setups with 2-4 telescopes and 36 light paths each. We distinguish between cases with and without additional background concentrations. Our approach parametrises the unknown distribution by local piecewise constant or linear functions on a regular grid and solves the resulting discrete, linear system by a least squares minimum norm principle. We show that the linear parametrisation not only allows better representation of the distributions in terms of discretisation errors, but also better inversion of the system. We calculate area integrals of the concentration field (i.e. total emissions rates for non-vanishing perpendicular wind speed components) and show that reconstruction errors and reconstructed area integrals within the peaks for narrow distributions crucially depend on the resolution of the reconstruction grid. A recently suggested grid translation method for the piecewise constant basis functions, combining reconstructions from several shifted grids, is modified for the linear basis functions and proven to reduce overall reconstruction errors, but not the uncertainty of concentration integrals. We suggest a procedure to subtract additional background concentration fields before inversion. We find large differences in reconstruction quality between the geometries and conclude that, in general, for a constant number of light paths increasing the number of telescopes leads to better reconstruction results. It appears that geometries that give better results for negligible measurement errors and parts of the geometry that are better resolved are also less sensitive to increasing measurement errors.

Hartl, A.; Song, B. C.; Pundt, I.

2005-11-01

26

Geometry  

NSDL National Science Digital Library

Geometry is the branch of mathematics which investigates the relations, properties, and measurement of solids, surfaces, lines, and angles. It is the science of the relations of space. Sourse: Webster's Dictionary

K-12 Outreach,

27

Geometry  

NSDL National Science Digital Library

Shapes, lines, and more! Here are some fun games to practice geometry and not get bored! Here\\'s a review to help you through the fun... Identify Geometric Shapes and then you will be on your way! After you have reviewed...show me all you know with this Shape Quiz and then all the fun begins!!! Is it a polygon or not? You tell me. Drag them into the bins and we will see! ...

Walker, Ms.

2008-03-31

28

Direct numerical solution of Poisson`s equation in cylindrical (r, z) coordinates  

SciTech Connect

A direct solver method is developed for solving Poisson`s equation numerically for the electrostatic potential {phi}(r,z) in a cylindrical region (r < R{sub wall}, 0 < z < L). The method assumes the charge density {rho}(r,z) and wall potential {phi}(r = R{sub wall}, z) are specified, and {partial_derivative}{phi}/{partial_derivative}z = 0 at the axial boundaries (z = 0, L).

Chao, E.H.; Paul, S.F.; Davidson, R.C. [Princeton Univ., NJ (United States). Princeton Plasma Physics Lab.; Fine, K.S. [Univ. of California, San Diego, La Jolla (Canada). Dept. of Physics

1997-07-22

29

2-D reconstruction of atmospheric concentration peaks from horizontal long path DOAS tomographic measurements: parametrisation and geometry within a discrete approach  

Microsoft Academic Search

In this study, we theoretically investigate the reconstruction of 2-D cross sections through Gaussian concentration distributions, e.g. emission plumes, from long path DOAS measurements along a limited number of light paths. This is done systematically with respect to the extension of the up to four peaks and for six different measurement setups with 2-4 telescopes and 36 light paths each.

A. Hartl; B. C. Song; I. Pundt

2005-01-01

30

2-D reconstruction of atmospheric concentration peaks from horizontal long path DOAS tomographic measurements: parametrisation and geometry within a discrete approach  

Microsoft Academic Search

In this study, we theoretically investigate the reconstruction of 2-D cross sections through Gaussian concentration distributions, e.g. emission plumes, from long path DOAS measurements along a limited number of light paths. This is done systematically with respect to the extension of the up to four peaks and for six different measurement setups with 2-4 telescopes and 36 light paths each.

A. Hartl; B. C. Song; I. Pundt

2006-01-01

31

Translating Basic Psychopathology Research to Preventive Interventions: A Tribute to John R. Z. Abela  

ERIC Educational Resources Information Center

This article highlights how the many important contributions of John R. Z. Abela's research program can inform the development and implementation of interventions for preventing depression in youth. Abela provided evidence of multiple vulnerabilities to depression including cognitive (e.g., inferential style, dysfunctional attitudes, ruminative…

Garber, Judy; Korelitz, Katherine; Samanez-Larkin, Silvia

2012-01-01

32

Translating Basic Psychopathology Research to Preventive Interventions: A Tribute to John R. Z. Abela  

ERIC Educational Resources Information Center

|This article highlights how the many important contributions of John R. Z. Abela's research program can inform the development and implementation of interventions for preventing depression in youth. Abela provided evidence of multiple vulnerabilities to depression including cognitive (e.g., inferential style, dysfunctional attitudes, ruminative…

Garber, Judy; Korelitz, Katherine; Samanez-Larkin, Silvia

2012-01-01

33

2-D analytic model for inductively coupled plasma sources. I. Electromagnetic model and kinetic analysis  

Microsoft Academic Search

Inductively coupled plasma sources (ICPS) have recently received increasing interest for semiconductor etching and deposition. A 2-D (r, z) electromagnetic (EM) model of ICPS is developed in terms of the mode analysis (MA) technique. Based upon the eigenmode expansion, a closed-form of the vector and scalar potentials of the EM fields is obtained, which provides exact and fast computing for

Fa Dai; Chwan-Hwa John Wu

1995-01-01

34

Efficient Computational Techniques for Toroidal Plasma Geometry in Transport Simulations  

NASA Astrophysics Data System (ADS)

Efficient algorithms for flux surface averaging and line tracking through a plasma are essential in many applications, e.g., pellet injection, beam deposition, current drive,geometry for transport equations and unfolding diagnostic measurements. These calculations may be fairly complicated and time consuming for more complex geometries. In this paper, an extensively revised version of the line tracking code TRACK( Attenberger, S., Houlberg, W., and Hirshman, S., J. Comput. Phys., 72), 435 (1987) is presented. Much of the original functionality has been improved with significant gains in speed. An efficient 3d flux surface averaging module, using an optimized grid, has been added to the suite of routines. The implementation, testing and application of the routines to the PELLET, BEAM and THRIFT (magnetic flux evolution) codes, in both 2d and 3d is discussed and illustrated. In addition, the related issue of obtaining flux surface averages from a ?(R,Z) representation is discussed in terms of a coordinate transform optimizing the averaging process. The PELLET and the modified TRACK modules are being prepared for submission to the NTCC module library.

Strand, Pär; Houlberg, Wayne

2000-10-01

35

A transient, quadratic nodal method for triangular-Z geometry  

Microsoft Academic Search

Many systematically-derived nodal methods have been developed for Cartesian geometry due to the extensive interest in Light Water Reactors. These methods typically model the transverse-integrated flux as either an analytic or low order polynomial function of position within the node. Recently, quadratic nodal methods have been developed for R-Z and hexagonal geometry. A static and transient quadratic nodal method is

DeLorey

1993-01-01

36

A transient, quadratic nodal method for triangular-Z geometry  

SciTech Connect

Many systematically-derived nodal methods have been developed for Cartesian geometry due to the extensive interest in Light Water Reactors. These methods typically model the transverse-integrated flux as either an analytic or low order polynomial function of position within the node. Recently, quadratic nodal methods have been developed for R-Z and hexagonal geometry. A static and transient quadratic nodal method is developed for triangular-Z geometry. This development is particularly challenging because the quadratic expansion in each node must be performed between the node faces and the triangular points. As a consequence, in the 2-D plane, the flux and current at the points of the triangles must be treated. Quadratic nodal equations are solved using a non-linear iteration scheme, which utilizes the corrected, mesh-centered finite difference equations, and forces these equations to match the quadratic equations by computing discontinuity factors during the solution. Transient nodal equations are solved using the improved quasi-static method, which has been shown to be a very efficient solution method for transient problems. Several static problems are used to compare the quadratic nodal method to the Coarse Mesh Finite Difference (CMFD) method. The quadratic method is shown to give more accurate node-averaged fluxes. However, it appears that the method has difficulty predicting node leakages near reactor boundaries and severe material interfaces. The consequence is that the eigenvalue may be poorly predicted for certain reactor configurations. The transient methods are tested using a simple analytic test problem, a heterogeneous heavy water reactor benchmark problem, and three thermal hydraulic test problems. Results indicate that the transient methods have been implemented correctly.

DeLorey, T.F.

1993-06-01

37

Blast wave simulation using AUTODYN2D: A parametric study  

Microsoft Academic Search

This paper is concerned with use of the hydrocode AUTODYN2D for the simulation of blast wave interactions with structures. A comprehensive parametric study is presented including an investigation of the effect of grid size on program output. Comparisons are made with well-established simple-geometry experimental data and with an experiment of more complex geometry. In both cases, results indicate that AUTODYN2D

T. C. Chapman; T. A. Rose; P. D. Smith

1995-01-01

38

The Analytic Function Expansion Nodal (AFEN) Method with Half-Interface Averaged Fluxes in Mixed Geometry Nodes for Analysis of Pebble Bed Modular Reactor (PBMR) Cores  

Microsoft Academic Search

The analytic function expansion nodal (AFEN) method has been successfully applied to the rectangular and hexagonal geometries in the cartesian coordinates system. In this paper, we extended the AFEN method to the cylindrical geometry in the R-Z coordinates for the analysis of pebble bed modular reactors (PBMRs). To treat the mixed geometry of rectangular and triangular nodes appearing in the

Do Sam KIM; Nam Zin CHO

2003-01-01

39

What we've learned from 3-D and r,z intense-beam simulations using the WARP code  

SciTech Connect

We describe a multi-dimensional discrete-particle simulation code, WARP, and its application to Heavy Ion Fusion beams. The code's 3-D package combines features of an accelerator code and a particle-in-cell plasma simulation, and can efficiently track beams through many lattice elements and around bends. The code's r, z package allows us to follow beams over very long times and models the accelerating module impedances. A number of applications are presented. These have led to an improved understanding of: Beam equilibria, and the approach to equilibrium; longitudinal beam dynamics and stability; electrostatic quadrupole (ESQ) injector aberrations; bending and recirculation of space-charge-dominated beams; and the drift-compression process. The code is being used for accelerator design, as well as for theoretical investigations.

Friedman, A.; Callahan, D.A.; Grote, D.P.; Langdon, A.B.; Lund, S.M. (Lawrence Livermore National Lab., CA (United States)); Haber, I. (Naval Research Lab., Washington, DC (United States))

1993-05-06

40

2D-RMHD Modeling of the Dynamics of a Ne Gas Puff Z Pinch  

NASA Astrophysics Data System (ADS)

Detailed spatially resolved spectroscopic analysis of a neon gas puff Z pinch on the Weizmann 1MA generator [1,2] indicates that the radius of the K-shell regions grows to a maximum and then decreases during the radiation pulse -- the opposite of that calculated by 1D-RMHD models. Here we compare Mach2 2D-RMHD [r-z, high resolution, moving grid, non-LTE atomic populations, 3D ray trace radiation transport] simulation results to the size of the K-shell emission region as inferred from the spectroscopic analysis. In addition 2D, 3-ns time gated visible light images recorded during the neon experiments give us the opportunity to compare with the evolution of the outer pinch radius, r(z,t), as calculated by the 2D-RMHD model. Comparisons with spectroscopically inferred results and simulation results will also be made for electron and ion temperatures as well as internal energy to study the weak ion and electron temperature equilibration observed in the data.[4pt] [1] E. Kroupp, et al., PRL, 98, 115001 (2007).[0pt] [2] D. Osin, Ph.D. Thesis (2008).

Thornhill, J.; Giuliani, J.; Dasgupta, A.; Velikovich, A.; Chong, Y.; Clark, R.; Kroupp, E.; Osin, D.; Maron, Y.; Starobinets, A.; Stambulchik, E.; Fisher, V.; Bernshtam, V.; Fisher, A.; Deeney, C.

2012-10-01

41

Lectures on 2D gravity and 2D string theory  

Microsoft Academic Search

This report discusses the following topics: loops and states in conformal field theory; brief review of the Liouville theory; 2D Euclidean quantum gravity 1 -- path integral approach; 2D Euclidean quantum gravity 2 -- canonical approach; states in 2D string theory; matrix model technology 1 -- method of orthogonal polynomials; matrix model technology 2 -- loops on the lattice; matrix

P. Ginsparg; Gregory Moore

1992-01-01

42

Stellar Aberration 2D  

NSDL National Science Digital Library

The Stellar Aberration 2D Model illustrates the phenomenon known as the aberration of starlight, first reported by James Bradley in 1729. Aberration occurs because light has a finite speed, and thus light from a star takes a finite amount of time to travel through the tube of a telescope. During this time, the telescope moves as a result of Earth's rotational and orbital motions (in this case, the orbital motion is more important because it is faster). Therefore, if the telescope is pointed directly at the star the starlight will hit the sides of the tube before reaching the eyepiece. To see the star the telescope must be pointed forward (i.e. in the direction of Earth's motion) very slightly. The simulation shows a telescope (depicted as a red rectangle) and a star (white point) directly overhead. When the simulation is run a pulse of light is emitted from the star and travels straight downward to Earth. The telescope moves to the right due to Earth's motion. As a result, if the telescope is pointed straight up (ie toward the actual location of the star) the pulse of light will not reach the bottom of the telescope. Controls allow the user to set the speed of Earth and the tilt of the telescope. The user can modify the tilt until the starlight reaches the bottom of the telescope. Alternately, the user can use the Options menu to set the telescope to the correct tilt for the current speed setting.

Timberlake, Todd

2011-05-18

43

A nodal integral method for the neutron diffusion equation in cylindrical geometry  

SciTech Connect

This Summary reports recent progress in deriving and numerically implementing a nodal integral method (NIM) for solving the neutron diffusion equation in cylindrical, r-z, geometry. Comparisons of numerical solutions to two test problems with those obtained by the code EXTERMINATOR-2 indicate the superior accuracy of the nodal integral method solutions on much coarser meshes. 6 refs., 1 fig., 1 tab.

Azmy, Y.Y.

1987-01-01

44

2D Mapping and LIF Tomography of an Expanding Magnetoplasma  

NASA Astrophysics Data System (ADS)

Previous experiments showed that adiabatic expansion of plasma provides high uniformity of ejected flux and up to 100 eV of ion energy from the electric field generated by the density gradient. Such plasmas are suitable for applications as plasma-based thrusters for spacecraft propulsion as well as energetic ion sources in plasma surface processing. We report on experiments performed in the expansion region between a steady state, high density, helicon plasma source and a large diffusion chamber (1.8 m diameter, 4.4 m length) in which the ion ? is below 10-2 but greater than m_e/m_i. 2D mapping has been accomplished by measuring the magnetic fluctuation spectrum, electron temperature, electron density, and plasma potential at different locations in the horizontal (r,z) plane. Furthermore, by using the rotation capability of our scanning probe we are able to obtain the entire 2D ion distribution function through tomographic inversion of chordal measurements. The ion flow results are consistent with the spontaneous formation of an electric double layer at the end of the helicon source.

Biloiu, C.; Compton, C.; Hardin, R.; Keesee, A.; McGeehan, B.; Scime, E.; Sun, X.

2003-10-01

45

Coupled electron\\/photon S[sub N] calculation in lattice geometry  

Microsoft Academic Search

The capabilities of the SMARTEPANTS (Simulating Many Accumulative Rutherford Trajectories Electron Photon and Neutral Transport Solver)-coupled charged\\/neutral particle transport S[sub N] Code have been extended from r-z and x-y-z geometry to x-y-z geometry with embedded cylinder. The basic idea is to accommodate cylindrical shapes using a rectangular mesh. To do this, the code allows for the replacement of any number

K. Hadad; W. L. Filippone

1993-01-01

46

Lectures on 2D gravity and 2D string theory  

SciTech Connect

This report the following topics: loops and states in conformal field theory; brief review of the Liouville theory; 2D Euclidean quantum gravity I: path integral approach; 2D Euclidean quantum gravity II: canonical approach; states in 2D string theory; matrix model technology I: method of orthogonal polynomials; matrix model technology II: loops on the lattice; matrix model technology III: free fermions from the lattice; loops and states in matrix model quantum gravity; loops and states in the C=1 matrix model; 6V model fermi sea dynamics and collective field theory; and string scattering in two spacetime dimensions.

Ginsparg, P. (Los Alamos National Lab., NM (United States)); Moore, G. (Yale Univ., New Haven, CT (United States). Dept. of Physics)

1992-09-17

47

2-D Finite Element Cable and Box IEMP Analysis  

SciTech Connect

A 2-D finite element code has been developed for the solution of arbitrary geometry cable SGEMP and box IEMP problems. The quasi- static electric field equations with radiation- induced charge deposition and radiation-induced conductivity y are numerically solved on a triangular mesh. Multiple regions of different dielectric materials and multiple conductors are permitted.

Scivner, G.J.; Turner, C.D.

1998-12-17

48

Random Walk 2D Model  

NSDL National Science Digital Library

The EJS Random Walk 2D Model simulates a 2-D random walk. You can change the number of walkers and probability of going a given direction. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The Random Walk 2D Model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_RandomWalk2D.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-04-27

49

2D NMR Metabonomic Analysis  

PubMed Central

Motivation Comparative metabolic profiling by nuclear magnetic resonance (NMR) is showing increasing promise for identifying inter-individual differences to drug response. Two dimensional (2D) 1H-13C NMR can reduce spectral overlap, a common problem of 1D 1H NMR. However, the peak alignment tools for 1D NMR spectra are not well suited for 2D NMR. An automated and statistically robust method for aligning 2D NMR peaks is required to enable comparative metabonomic analysis using 2D NMR. Results A novel statistical method was developed to align NMR peaks that represent the same chemical groups across multiple 2D NMR spectra. The degree of local pattern match among peaks in different spectra is assessed using a similarity measure, and a heuristic algorithm maximizes the similarity measure for peaks across the whole spectrum. This peak alignment method was used to align peaks in 2D NMR spectra of endogenous metabolites in liver extracts obtained from four inbred mouse strains in the study of acetaminophen-induced liver toxicity. This automated alignment method was validated by manual examination of the top fifty peaks as ranked by signal intensity. Manual inspection of 1872 peaks in 39 different spectra demonstrated that the automated algorithm correctly aligned 1810 (96.7%) peaks. Availability Algorithm is available upon request. Contact guochun.liao@roche.com

Zheng, Ming; Lu, Peng; Liu, Yanzhou; Pease, Joseph; Usuka, Jonathan; Liao, Guochun; Peltz, Gary

2007-01-01

50

Extensions of 2D gravity  

SciTech Connect

After reviewing some aspects of gravity in two dimensions, I show that non-trivial embeddings of sl(2) in a semi-simple (super) Lie algebra give rise to a very large class of extensions of 2D gravity. The induced action is constructed as a gauged WZW model and an exact expression for the effective action is given.

Sevrin, A.

1993-06-01

51

Turbulence in MESA-2D.  

National Technical Information Service (NTIS)

The MESA-2D Eulerian, compressible flow code has been extended to include the effects of turbulence. In this turbulence model, transport equations for the turbulent kinetic energy k, the turbulent scale s, and the turbulence mass flux components a(sub i) ...

B. Daly

1992-01-01

52

Synthesis and structural transformations of colloidal 2D layered metal chalcogenide nanocrystals.  

PubMed

This review presents recent advances in synthetic methods and structural transformations of colloidal 2D layered metal chalcogenide nanocrystals. Planar 2D anisotropy and interlayer van der Waals gaps are the important characteristics of these nanocrystals for pristine disc, plate or sheet morphologies. These 2D nanocrystals undergo unique chemical transformations upon exposure to external chemical stimuli and newly obtained structures are 2D nanostructures with high complexity in their morphological geometries and chemical compositions. Finally, future opportunities and potential applications of 2D layered metal chalcogenide nanocrystals are briefly discussed. PMID:23212120

Han, Jae Hyo; Lee, Sujeong; Cheon, Jinwoo

2013-04-01

53

Multi-Chart Geometry Images  

Microsoft Academic Search

We introduce multi-chart geometry images, a new representation for arbitrary surfaces. It is created by resampling a surface onto a regular 2D grid. Whereas the original scheme of Gu et al. maps the entire surface onto a single square, we use an atlas construction to map the surface piecewise onto charts of arbitrary shape. We demonstrate that this added flexibility

Pedro V. Sander; Zoë J. Wood; Steven J. Gortler; John Snyder; Hugues Hoppe

2003-01-01

54

Geometry Information  

NSDL National Science Digital Library

This article from New Zealand maths contains justifications for teaching geometry in the elementary grades and thoughts on how children learn geometry, including ideas from Piaget and the van Hieles. The article concludes with an example of how adults in a non-school setting would apply the van Hiele stages in an unfamiliar space.

2010-01-01

55

Projective Geometry  

NSDL National Science Digital Library

This site departs from the common themes taught in general geometry classes and introduces projective geometry, which has to do with special properties resulting from the intersection of lines, planes, and points. The coincidence of such elements is what is referred to as an incidence, and this is the basis of the topic. The site makes extensive use of animated figures to demonstrate principles involved in projective geometry, such as path curves, pivot transforms, and the curious concept of counter space. The author does a good job of explaining what is depicted in the figures as well as the underlying theory.

56

Systolic arrays for 2D digital filters  

NASA Astrophysics Data System (ADS)

Systolic architectures for 2D digital filters are presented. The structures are derived directly from the transfer function. The proposed 2D systolic arrays for 2D digital filters have several advantages over the existing 2D arrays, such as modularity and use of nearest neighbor interconnections. These two features make the proposed architecture versatile and more suitable for VLSI implementation.

Aggoun, Amar

1997-12-01

57

2D Gauge Field Theory  

SciTech Connect

We show from the action integral that under the assumption of longitudinal dominance and transverse confinement, QCD4 in (3+1) dimensional space-time can be approximately compactified into QCD2 in (1+1) dimensional space-time. In such a process, we find the relation between the coupling constant $g(2D)$ in QCD2 and the coupling constant $g(4D)$ in QCD4. We also show that quarks and gluons in QCD2 acquire masses as a result of the compactification.

Koshelkin, Andrey V. [Moscow Institute for Physics and Engineering, Russia; Wong, Cheuk-Yin [ORNL

2012-01-01

58

Geometry Sender  

NSDL National Science Digital Library

The Geometry Sender at Keio University includes many 3D object data, including WebOOGL, off, rwx format, tutorial on data formats, and information about external viewers for 3D object on Web are available.

59

Fast regular 2D algorithms for trigonometric transforms  

NASA Astrophysics Data System (ADS)

2D fast cosine and sine transforms with regular structure are developed for 2n X 2n data points. These algorithms are extended versions of the 1D fast regular algorithms introduced in our recent paper. The rationale for these 2D algorithms for sine/cosine transforms in a 2D decomposition of data sequences into 2D subblocks with reduced dimension, rather than 1D, separable treatments for the columns and rows of the data sets. As a result the number of multiplications is 25 percent less than in row- column approach. Numerous algorithms of these type were proposed previously for discrete Fourier transform (DFT) and discrete cosine transform of type 2 (DCT-II). In DCT-II case the algorithms do not have a regular structure as is the case in DFT algorithms and motivation of this work is to derive 2D algorithms for discrete sine and cosine transforms with regular constant geometry structures. Extension to 2n X 2m data points is straightforward.

Astola, Jaakko T.; Akopian, David

1997-01-01

60

Sacred Geometry  

NSDL National Science Digital Library

The material on this website is used for a course taught at Dartmouth University called, Geometry in Art and Architecture. The website presents several images of "polygons, tilings & sacred geometry" along with descriptions of the geometric patterns. Although the text is obviously written for students who follow a particular course and hasn't been updated since 2002, the author provides some interesting examples of how the fields of art and mathematics overlap. Information on the author's book on the subject and bibliographical references are also posted for anyone wanting to explore this topic further.

61

Algebraic Geometry  

NSDL National Science Digital Library

A short article designed to provide an introduction to algebraic geometry, which combines the algebraic with the geometric for the benefit of both. Thus the recent proof of "Fermat's Last Theorem" - ostensibly a statement in number theory - was proved with geometric tools. Conversely, the geometry of sets defined by equations is studied using quite sophisticated algebraic machinery. This is an enticing area but the important topics are quite deep. This area includes elliptic curves. Applications and related fields and subfields; textbooks, reference works, and tutorials; software and tables; other web sites with this focus.

Rusin, David J., 1957-

2007-12-18

62

2-D axisymmetric line transport  

SciTech Connect

The methods used in the ALTAIR code for computing the transfer of spectral line radiation in two-dimensional axially-symmetric geometry are described. ALTAIR uses a variable-Eddington-tensor approach, in which the transfer equation of non-coherent line scattering is written in moment form, and the moments are closed with an assumed tensor relating the monochromatic pressure tensor and energy density; this Eddington tensor is obtained self-consistently using an accurate angle-dependent solution of the transfer equation. The finite element method for solving the moment system, and the discontinuous finite element method for solving the S{sub n} equation of transfer are described. Two applications of the method are discussed: line formation in uniform cylinders with different length-diameter ratios, and monochromatic transfer on an irregular x-y mesh (the Mordant test problem). 13 refs., 2 figs.

Castor, J.I.; Dykema, P.G. (Lawrence Livermore National Lab., CA (USA)); Klein, R.I. (Lawrence Livermore National Lab., CA (USA) California Univ., Berkeley, CA (USA). Dept. of Astronomy)

1990-11-20

63

Synthesizing 2D directional moving texture  

Microsoft Academic Search

We present a novel patch-based algorithm for synthesizing a moving 2D texture, i.e. a sequence of frame-coherent 2D textures. In our method, the input are a sample texture and a 2D flow field. We first synthesize a 2D directional texture according to the direction information of the flow field and then let the texture move following the flow. Iteratively, the

Bin Wang; Wenping Wang; Junhai Yong; Jiaguang Sun

2005-01-01

64

2D Seismic Slope Tomography  

NASA Astrophysics Data System (ADS)

Stereotomography is an inverse method devoted to crustal velocity estimation from seismic data. Its specificity is to use not only sources to receivers travel times but also slopes both at sources and receivers. These data are automatically picked on semblance panels. Data modelling is based on ray theory in an istropic media. Model includes both velocity field and rays parameters in order to account for all the data uncertainties ( sources and receivers locations, travel times and slopes). The method, initially dedicated to invert reflections and diffractions from conventional marine acquisition, has already been applied on various real data set. In order to better constrain inversion, further developpements are necessary in a more general frame including alternative acquisitions geometries (OBC, OBS, walk-away, VSP). Final goal is to jointly invert direct and reflected arrivals from the whole data set. First, we concentrate on borehole direct arrivals. The specific parametrization of stereotomographic model, including both velocity field and rays parameters, leads us to propose an original way to process direct arrivals at well : pairs of first arrivals are created and processed as surface data. Such an approach allows to keep the same inversion formalism. Moreover, specific informations brought by direct arrivals, such as one way travel times, are introduced in inversion process as a priori information.

Gosselet, A.; Le Begat, S.

2002-12-01

65

NKG2D ligands as therapeutic targets.  

PubMed

The Natural Killer Group 2D (NKG2D) receptor plays an important role in protecting the host from infections and cancer. By recognizing ligands induced on infected or tumor cells, NKG2D modulates lymphocyte activation and promotes immunity to eliminate ligand-expressing cells. Because these ligands are not widely expressed on healthy adult tissue, NKG2D ligands may present a useful target for immunotherapeutic approaches in cancer. Novel therapies targeting NKG2D ligands for the treatment of cancer have shown preclinical success and are poised to enter into clinical trials. In this review, the NKG2D receptor and its ligands are discussed in the context of cancer, infection, and autoimmunity. In addition, therapies targeting NKG2D ligands in cancer are also reviewed. PMID:23833565

Spear, Paul; Wu, Ming-Ru; Sentman, Marie-Louise; Sentman, Charles L

2013-05-01

66

Fractal Geometry  

NSDL National Science Digital Library

This is a web site to support a first course in fractal geometry for students without a strong mathematical background. It covers a wide range of topics in fractals, modern dynamics, and chaos. Each of the topics contains examples of fractals in the arts, humanities, or social sciences. The site also contains lesson plans and software that can be used for a broad range of classes.

Frame, Michael; Mandelbrot, Benoit

2004-11-30

67

2-D and 3-D computations of curved accelerator magnets  

SciTech Connect

In order to save computer memory, a long accelerator magnet may be computed by treating the long central region and the end regions separately. The dipole magnets for the injector synchrotron of the Advanced Photon Source (APS), now under construction at Argonne National Laboratory (ANL), employ magnet iron consisting of parallel laminations, stacked with a uniform radius of curvature of 33.379 m. Laplace's equation for the magnetic scalar potential has a different form for a straight magnet (x-y coordinates), a magnet with surfaces curved about a common center (r-{theta} coordinates), and a magnet with parallel laminations like the APS injector dipole. Yet pseudo 2-D computations for the three geometries give basically identical results, even for a much more strongly curved magnet. Hence 2-D (x-y) computations of the central region and 3-D computations of the end regions can be combined to determine the overall magnetic behavior of the magnets. 1 ref., 6 figs.

Turner, L.R.

1991-01-01

68

VECTUM. Irregular 2D Velocity Vector Field Plotting Package  

SciTech Connect

VECTUM is a NCAR Graphics based package, for generating a plot of an irregular 2D velocity vector field. The program reads an ASCII database of x, y, u, v, data pairs and produces a plot in Computer Graphics Metafile (CGM) format. The program also uses an ASCII parameter file for controlling annotation details such as the plot title, arrowhead style, scale of vectors, windowing, etc. Simple geometry (i.e. lines, arcs, splines) can be defined to be included with the velocity vectors. NCAR Graphics drivers can be used to display the CGM file into PostScript, HPGL, HDF, etc, output.

McClurg, F.R.; Mousseau, V.A. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

1992-05-04

69

Fractal Geometry  

NSDL National Science Digital Library

This is one of the best online resources about fractals, and is "meant to support a first course in fractal geometry for students without especially strong mathematical preparation." The site is incredibly deep, providing everything from the most basic definitions and non-technical discussions to involved mathematical formulations. Interactive Java applets, downloadable software for the PC and Macintosh, and laboratory activities are also presented. A particularly interesting section of the site explores about 100 places in nature and society where fractals are found.

Frame, Michael; Mandelbrot, Benoit; Neger, Nial

70

Toward Broad Bandwidth 2-D Electronic Spectroscopy: Correction of Chirp From a Continuum Probe  

Microsoft Academic Search

Recent implementations of 2-D spectroscopy in the pump–probe geometry using a pulse-shaper demonstrate the ease with which frequency-resolved pump–probe experiments can be readily adapted to 2-D methods. Many frequency-resolved pump–probe experiments employ continuum probes to observe a broad range of electronic transitions. These continuum probes are often chirped, leading to distortions that can be postcorrected by characterizing the chirp and

Patrick A. Tekavec; Kristin L. M. Lewis; Franklin D. Fuller; Jeffrey A. Myers; Jennifer P. Ogilvie

2012-01-01

71

Iconic Indexing by 2-D Strings  

Microsoft Academic Search

In this paper, we describe a new way of representing a symbolic picture by a two-dimensional string. A picture query can also be specified as a 2-D string. The problem of pictorial information retrieval then becomes a problem of 2-D subsequence matching. We present algorithms for encoding a symbolic picture into its 2-D string representation, reconstructing a picture from its

Shi-Kuo Chang; Qing-Yun Shi; Cheng-Wen Yan

1987-01-01

72

Hamiltonian approach to 2D supergravity.  

National Technical Information Service (NTIS)

2D supergravity is studied in a covariant and gauge independent way. The theory is obtained from 2D bosonic gravity following the square root method and the diffeomorphism superalgebra is explicitly computed. This approach could be a procedure for introdu...

J. Gamboa C. Ramirez

1992-01-01

73

Tubular anisotropy for 2D vessel segmentation  

Microsoft Academic Search

In this paper, we present a new approach for segmentation of tubular structures in 2D images providing minimal interaction. The main objective is to extract centerlines and boundaries of the vessels at the same time. The first step is to represent the trajectory of the vessel not as a 2D curve but to go up a dimension and represent the

Fethallah Benmansour; Laurent D. Cohen; M. Law; A. Chung

2009-01-01

74

Tubular anisotropy for 2D vessel segmentation  

Microsoft Academic Search

In this paper, we present a new approach for segmenta- tion of tubular structures in 2D images providing minimal interaction. The main objective is to extract centerlines and boundaries of the vessels at the same time. The first step is to represent the trajectory of the vessel not as a 2D curve but to go up a dimension and represent

Fethallah Benmansour; Laurent D. Cohen; Max W. K. Law; Albert Chung

2009-01-01

75

Thermal-stress analysis by coupling NIKE2D and TACO2D. [Tank rubber tracks  

Microsoft Academic Search

Several tank track designs were evaluated for the heating of the rubber pads. NIKE2D was used to analyze the rubber pads under mechanical loading and TACO2D to calculate thermal distributions within the pads. (DLC)

1984-01-01

76

2D Radiation MHD K-shell Modeling of Single Wire Array Stainless Steel Experiments on the Z Machine  

SciTech Connect

Many physical effects can produce unstable plasma behavior that affect K-shell emission from arrays. Such effects include: asymmetry in the initial density profile, asymmetry in power flow, thermal conduction at the boundaries, and non-uniform wire ablation. Here we consider how asymmetry in the radiation field also contributes to the generation of multidimensional plasma behavior that affects K-shell power and yield. To model this radiation asymmetry, we have incorporated into the MACH2 r-z MHD code a self-consistent calculation of the non-LTE population kinetics based on radiation transport using multi-dimensional ray tracing. Such methodology is necessary for modeling the enhanced radiative cooling that occurs at the anode and cathode ends of the pinch during the run-in phase of the implosion. This enhanced radiative cooling is due to reduced optical depth at these locations producing an asymmetric flow of radiative energy that leads to substantial disruption of large initial diameter (>5 cm) pinches and drives 1D into 2D fluid (i.e., Rayleigh-Taylor like) flows. The impact of this 2D behavior on K-shell power and yield is investigated by comparing 1D and 2D model results with data obtained from a series of single wire array stainless steel experiments performed on the Z generator.

Thornhill, J. W.; Giuliani, J. L.; Apruzese, J. P.; Chong, Y. K.; Davis, J.; Dasgupta, A. [Plasma Physics Division, Naval Research Laboratory, Washington DC 20375 (United States); Whitney, K. G.; Clark, R. W. [Berkeley Research Associates, Beltsville Maryland 20705 (United States); Jones, B.; Coverdale, C. A.; Ampleford, D. J.; Cuneo, M. E. [Sandia National Laboratories, Albuquerque NM 87545 (United States); Deeney, C. [National Nuclear Security Administration, Washington DC 20585 (United States)

2009-01-21

77

Toward a 2-D magneto-optical trap for polar molecules  

NASA Astrophysics Data System (ADS)

The additional structure that arises from the rotational degree of freedom in diatomic molecules makes difficult the adaptation of a traditional atomic magneto-optical trap (MOT) for use with molecules. We describe progress toward development of a 2-D MOT for laser cooled yttrium monoxide molecules based on a resonant LC baseball coil geometry.

Hummon, Matthew; Stuhl, Benjamin; Yeo, Mark; Collopy, Alejandra; Ye, Jun

2012-06-01

78

Photoacoustic imaging for deep targets in the breast using a multichannel 2D array transducer  

Microsoft Academic Search

A photoacoustic (PA) imaging system was developed to achieve high sensitivity for the detection and characterization of vascular anomalies in the breast in the mammographic geometry. Signal detection from deep in the breast was achieved by a broadband 2D PVDF planar array that has a round shape with one side trimmed straight to improve fit near the chest wall. This

Zhixing Xie; Xueding Wang; Richard F. Morris; Frederic R. Padilla; Gerald L. Lecarpentier; Paul L. Carson

2011-01-01

79

Matrix models of 2d gravity  

NASA Astrophysics Data System (ADS)

These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date.

Ginsparg, P.

80

Matrix models of 2d gravity  

Microsoft Academic Search

These are introductory lectures for a general audience that give an overview of the subject of matrix models and their application to random surfaces, 2d gravity, and string theory. They are intentionally 1.5 years out of date.

P. Ginsparg

1991-01-01

81

Nexus 2D 2008 Team Description  

Microsoft Academic Search

This paper presents an overview of our 2D Soccer S imulation Team. The main development features were done on decision making, action selection, and coach agent strategy making module using fuzzy logic mechanism and game theory approach.

Amin Milani Fard; M. Hossein Ansari; Armin Ildermi; Sina Molavipour; Mahdi Aledaghi; Farid Seifi; Mahmoud Naghibzadeh

2008-01-01

82

Brittle damage models in DYNA2D  

SciTech Connect

DYNA2D is an explicit Lagrangian finite element code used to model dynamic events where stress wave interactions influence the overall response of the system. DYNA2D is often used to model penetration problems involving ductile-to-ductile impacts; however, with the advent of the use of ceramics in the armor-anti-armor community and the need to model damage to laser optics components, good brittle damage models are now needed in DYNA2D. This report will detail the implementation of four brittle damage models in DYNA2D, three scalar damage models and one tensor damage model. These new brittle damage models are then used to predict experimental results from three distinctly different glass damage problems.

Faux, D.R.

1997-09-01

83

A comprehensive 2-D divertor data set from DIII-D for edge theory validation  

SciTech Connect

A comprehensive set of experiments has been carried out on the DIII-D tokamak to measure the 2-D (R,Z) structure of the divertor plasma in a systematic way using new diagnostics. Measurements cover the divertor radially from inside the X-point to the outer target plate and vertically from the target plate to above the X-point. Identical, repeatable shots were made, each having radial sweeps of the X-point and divertor strike points, to allow complete plasma and radiation profile measurements. Data have been obtained in ohmic, L-mode, ELMing H-mode, and reversed B{sub T} operation ({gradient}B drift away from the X-point). In addition, complete measurements were made of radiative divertor plasmas with a Partially Detached Divertor (PDD) induced by D{sub 2} injection and with a Radiating Mantle induced by Impurity injection (RMI) using neon and nitrogen. The data set includes first observations of the radial and poloidal profiles of the X-point, inner and outer leg plasmas in PDD and RMI radiative divertor operation. Preliminary data analysis shows that intrinsic impurities play a critical role in determining the SOL and divertor conditions.

Fenstermacher, M.E.; Allen, S.L.; Hill, D.N. [and others

1996-02-01

84

Rat CYP2D2, not 2D1, is functionally conserved with human CYP2D6 in endogenous morphine formation.  

PubMed

The assumption that CYP2D1 is the corresponding rat cytochrome to human CYP2D6 has been revisited using recombinant proteins in direct enzyme assays. CYP2D1 and 2D2 were incubated with known CYP2D6 substrates, the three morphine precursors thebaine, codeine and (R)-reticuline. Mass spectrometric analysis showed that rat CYP2D2, not 2D1, catalyzed the 3-O-demethylation reaction of thebaine and codeine. In addition, CYP2D2 incubated with (R)-reticuline generated four products corytuberine, pallidine, salutaridine and isoboldine while rat CYP2D1 was completely inactive. This intramolecular phenol-coupling reaction follows the same mechanism as observed for CYP2D6. Michaelis-Menten kinetic parameters revealed high catalytic efficiencies for rat CYP2D2. These findings suggest a critical evaluation of other commonly accepted, however untested, CYP2D1 substrates. PMID:22641033

Grobe, Nadja; Kutchan, Toni M; Zenk, Meinhart H

2012-05-26

85

Rat CYP2D2, not 2D1, is functionally conserved with human CYP2D6 in endogenous morphine formation  

PubMed Central

The assumption that CYP2D1 is the corresponding rat cytochrome to human CYP2D6 has been revisited using recombinant proteins in direct enzyme assays. CYP2D1 and 2D2 were incubated with known CYP2D6 substrates, the three morphine precursors thebaine, codeine and (R)-reticuline. Mass spectrometric analysis showed that rat CYP2D2, not 2D1, catalyzed the 3-O-demethylation reaction of thebaine and codeine. In addition, CYP2D2 incubated with (R)-reticuline generated four products corytuberine, pallidine, salutaridine and isoboldine while rat CYP2D1 was completely inactive. This intramolecular phenol-coupling reaction follows the same mechanism as observed for CYP2D6. Michaelis-Menten kinetic parameters revealed high catalytic efficiencies for rat CYP2D2. These findings suggest a critical evaluation of other commonly accepted, however untested, CYP2D1 substrates.

Grobe, Nadja; Kutchan, Toni M.; Zenk, Meinhart H.

2012-01-01

86

Comparison between 2-D cross correlation with 2-D sub-sampling and 2-D tracking using beam steering.  

PubMed

We have previously presented multi-dimensional sub-sample motion estimation techniques that use multi-dimensional polynomial fitting to the discrete cross-correlation function to jointly estimate the sub-sample motion in all three spatial directions. Previous simulation and experimental results showed that these estimators significantly improve the performance of the motion estimation in 2-D and 3-D. In this short communication, we present additional simulation results and compare these techniques to 2-D tracking using beam steering. The results show that beam steering technique performs better in estimating the motion vector especially the lateral component. PMID:21859570

Azar, Reza; Goksel, Orcun; Salcudean, Septimiu

2011-08-01

87

Steady 2D Detonations and the DSD Theory  

NASA Astrophysics Data System (ADS)

In the framework of the simplest DSD theory we obtained ODEs describing steady 2D detonation front shapes for slab, cylinder, and rib geometries. It was found that one solution (a steady detonation front shape) corresponds to several combinations of the confinement material and the defining charge dimension (slab thickness, cylinder radius, or inner rib radius). Comparing experimental data for these combinations and analyzing the shape difference at the edge provide information on the D(?) relation at low D. The analysis of the data on IHE ribs detonation indicates that as D decreases total curvature ? tends to a limit of about 0.1 mm-1, i.e., double the reciprocal critical diameter. This correction makes the DSD theory consistent with the experimental critical diameter.

Lubyatinsky, S. N.; Loboiko, B. G.; Filin, V. P.; Kostitsin, O. V.; Smirnov, E. B.

2006-07-01

88

Aerodynamic shape optimization of Airfoils in 2-D incompressible flow  

NASA Astrophysics Data System (ADS)

An optimization framework was developed for maximizing the region of 2-D airfoil immersed in laminar flow with enhanced aerodynamic performance. It uses genetic algorithm over a population of 125, across 1000 generations, to optimize the airfoil. On a stand-alone computer, a run takes about an hour to obtain a converged solution. The airfoil geometry was generated using two Bezier curves; one to represent the thickness and the other the camber of the airfoil. The airfoil profile was generated by adding and subtracting the thickness curve from the camber curve. The coefficient of lift and drag was computed using potential velocity distribution obtained from panel code, and boundary layer transition prediction code was used to predict the location of onset of transition. The objective function of a particular design is evaluated as the weighted-average of aerodynamic characteristics at various angles of attacks. Optimization was carried out for several objective functions and the airfoil designs obtained were analyzed.

Rangasamy, Srinivethan; Upadhyay, Harshal; Somasekaran, Sandeep; Raghunath, Sreekanth

2010-11-01

89

EJS 2D-Ising Model  

NSDL National Science Digital Library

The EJS 2D Ising model displays a lattice of spins. You can change the lattice size, temperature, and external magnetic field. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The 2D-Ising model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_Ising2D.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-02-20

90

Simulations of 2D and 3D Scaled Supernova Jet Experiments at Omega*  

NASA Astrophysics Data System (ADS)

Over the last few years we have fielded numerous jet experiments on the NOVA and OMEGA lasers (invited talk by Foster et al., this conference). We are now transitioning these experiments to more closely simulate scaled supernova jets during the explosion phase. In particular, we have fielded shots on OMEGA that investigate the difference between jets created by ablating a 3D (r,z) cylindrical pin versus a 2D (x,y) finite linear ridge. The Brominated CH pin or ridge is mounted symmetrically on the axis at the end of a laser-heated halfraum such that the radiation ablation is symmetric. The jet enters a cylinder of carbon foam and transmission radiographs are taken at different times and at two angles perpendicular to the symmetry axis. The LLNL 2-dimensional ALE and the LANL 3-dimensional Adaptive-Mesh-Refinement RAGE codes were used to design these experiments. Although 2-dimensional calculations are sufficient for the 3D cylindrical pin, 3-dimensional calculations are required for the 2D linear ridge due to its finite nature. To minimize 3-dimensional effects for the ridge, only the central section was Brominated with the ends made out of polyimide at the same density. Brominated and polyimide parts were also used in the pin to act as tagging that allows tracking the motion of different parts of the pin. In this poster, the calculations by the different codes will be compared to each other and to the data. These kinds of jet experiments should prove to be useful as validation for the new 3-dimensional codes being developed by the astrophysical community. *This work is performed under the auspices of the U. S. Department of Energy by the Los Alamos National Laboratory Laboratory under Contract No. W-7405-ENG-36, Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48, and the Laboratory for Laser Energetics under Contract No. DE-FC03-92SF19460.

Wilde, B. H.; Edwards, M. J.; Rosen, P. A.; Foster, J. M.; Remington, B. A.; Perry, T. S.

2001-10-01

91

The 2D lingual appliance system.  

PubMed

The two-dimensional (2D) lingual bracket system represents a valuable treatment option for adult patients seeking a completely invisible orthodontic appliance. The ease of direct or simplified indirect bonding of 2D lingual brackets in combination with low friction mechanics makes it possible to achieve a good functional and aesthetic occlusion, even in the presence of a severe malocclusion. The use of a self-ligating bracket significantly reduces chair-side time for the orthodontist, and the low-profile bracket design greatly improves patient comfort. PMID:24005953

Cacciafesta, Vittorio

2013-09-01

92

TOPAZ2D heat transfer code users manual and thermal property data base  

SciTech Connect

TOPAZ2D is a two dimensional implicit finite element computer code for heat transfer analysis. This user's manual provides information on the structure of a TOPAZ2D input file. Also included is a material thermal property data base. This manual is supplemented with The TOPAZ2D Theoretical Manual and the TOPAZ2D Verification Manual. TOPAZ2D has been implemented on the CRAY, SUN, and VAX computers. TOPAZ2D can be used to solve for the steady state or transient temperature field on two dimensional planar or axisymmetric geometries. Material properties may be temperature dependent and either isotropic or orthotropic. A variety of time and temperature dependent boundary conditions can be specified including temperature, flux, convection, and radiation. Time or temperature dependent internal heat generation can be defined locally be element or globally by material. TOPAZ2D can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in material surrounding the enclosure. Additional features include thermally controlled reactive chemical mixtures, thermal contact resistance across an interface, bulk fluid flow, phase change, and energy balances. Thermal stresses can be calculated using the solid mechanics code NIKE2D which reads the temperature state data calculated by TOPAZ2D. A three dimensional version of the code, TOPAZ3D is available. The material thermal property data base, Chapter 4, included in this manual was originally published in 1969 by Art Edwards for use with his TRUMP finite difference heat transfer code. The format of the data has been altered to be compatible with TOPAZ2D. Bob Bailey is responsible for adding the high explosive thermal property data.

Shapiro, A.B.; Edwards, A.L.

1990-05-01

93

Modelling RF sources using 2-D PIC codes  

SciTech Connect

In recent years, many types of RF sources have been successfully modelled using 2-D PIC codes. Both cross field devices (magnetrons, cross field amplifiers, etc.) and pencil beam devices (klystrons, gyrotrons, TWT`S, lasertrons, etc.) have been simulated. All these devices involve the interaction of an electron beam with an RF circuit. For many applications, the RF structure may be approximated by an equivalent circuit, which appears in the simulation as a boundary condition on the electric field (``port approximation``). The drive term for the circuit is calculated from the energy transfer between beam and field in the drift space. For some applications it may be necessary to model the actual geometry of the structure, although this is more expensive. One problem not entirely solved is how to accurately model in 2-D the coupling to an external waveguide. Frequently this is approximated by a radial transmission line, but this sometimes yields incorrect results. We also discuss issues in modelling the cathode and injecting the beam into the PIC simulation.

Eppley, K.R.

1993-03-01

94

Modelling RF sources using 2-D PIC codes  

SciTech Connect

In recent years, many types of RF sources have been successfully modelled using 2-D PIC codes. Both cross field devices (magnetrons, cross field amplifiers, etc.) and pencil beam devices (klystrons, gyrotrons, TWT'S, lasertrons, etc.) have been simulated. All these devices involve the interaction of an electron beam with an RF circuit. For many applications, the RF structure may be approximated by an equivalent circuit, which appears in the simulation as a boundary condition on the electric field ( port approximation''). The drive term for the circuit is calculated from the energy transfer between beam and field in the drift space. For some applications it may be necessary to model the actual geometry of the structure, although this is more expensive. One problem not entirely solved is how to accurately model in 2-D the coupling to an external waveguide. Frequently this is approximated by a radial transmission line, but this sometimes yields incorrect results. We also discuss issues in modelling the cathode and injecting the beam into the PIC simulation.

Eppley, K.R.

1993-03-01

95

2D models for dust-driven AGB star winds  

NASA Astrophysics Data System (ADS)

New axisymmetric (2D) models for dust-driven winds of C-stars are presented which include hydrodynamics with radiation pressure on dust, equilibrium chemistry and time-dependent dust formation with coupled grey Monte Carlo radiative transfer. Considering the simplest case without stellar pulsation (hydrostatic inner boundary condition) these models reveal a more complex picture of the dust formation and wind acceleration than earlier published spherically symmetric (1D) models. The so-called exterior ?-mechanism causes radial oscillations with short phases of active dust formation between longer phases without appreciable dust formation, just like in the 1D models. However, in 2D geometry, the oscillations can be out-of-phase at different places above the stellar atmosphere which results in the formation of dust arcs or smaller caps that only occupy a certain fraction of the total solid angle. These dust structures are accelerated outward by radiation pressure, expanding radially and tangentially like mushroom clouds, while dust-poor matter is falling back towards the star at other places. A highly dynamical and turbulent dust formation zone is created in this way, which again leads to inhomogeneous dust production. Further away from the star, flow instabilities (e.g. Rayleigh-Taylor) have time to fragment the outward moving arcs and shells to produce numerous small-scale cloud-like sub-structures.

Woitke, P.

2006-06-01

96

2D Mesoscale Simulations of Projectile Penetration into Sand  

NASA Astrophysics Data System (ADS)

Physical Phenomena governing projectile instabilities during penetration of granular media (e.g. sand) are not well understood. To gain insight into projectile -- granular media interactions, 2-D mesoscale simulations were performed to examine projectile penetration into sand targets with explicit representation of sand grains and representative porosities. The computational procedure used to generate a mesoscale representation of a sand target is presented with emphasis on an energy minimization technique for grain placement and modified Voronoi tessellations to enforce desired grain size and geometry. Simulated sand targets are shown to reproduce grain size distributions and porosities as large as 30% in close agreement with input parameters. Further, initial results from 2D mesoscale simulations, using the ISP-TROTP code, of normal impact of ogive shaped impactors at 0.5 km/s, 1.0 km/s, and 1.5 km/s impact velocities show that heterogeneous deformation in a frictionless granular media can cause deviation of projectile motion from normal direction indicating projectile instability during penetration. Efforts to achieve an improved description of granular media are underway. Work supported by DOE and AFOSR.

Teeter, R. D.; Dwivedi, S. K.; Felice, C. W.; Gupta, Y. M.

2007-06-01

97

MORSE-CGA: a Monte Carlo radiation transport code with array geometry capability  

Microsoft Academic Search

The MORSE-CG computer code system has been revised to add a new geometry module MARS, which is the combinatorial geometry package that allows multiple arrays for specifying geometries. The new code system is known as MORSE-CGA where CGA indicates Combinatorial Geometry Array. The PICTURE code, which makes printer plots of 2-D slices through a combinatorial geometry mock-up, has also been

Emmett

1985-01-01

98

A Quasi 2-D Localized Corrosion Model  

Microsoft Academic Search

In 1996 Pots has written a two-dimensional (2-D) stochastic algorithm to simulate the morphology of localized attack. The rule based algorithm operates on the assumption that the morphology of corrosion attack depends on the balance of two processes: corrosion (leading to metal loss) and precipitation (leading to metal protection). The rules of the original algorithm were modified to enable simulation

Srdjan Nesic; Ying Xiao; Bernardus Pots

2004-01-01

99

Modeling of 2-D DNA display.  

PubMed

2-D display is a fast and economical way of visualizing polymorphism and comparing genomes, which is based on the separation of DNA fragments in two steps, first according to their size and then to their sequence composition. In this article, we present an exhaustive study of the numerical issues associated with a model aimed at predicting the final absolute locations of DNA fragments in 2-D display experiments. We show that simple expressions for the mobility of DNA fragments in both dimensions allow one to reproduce experimental final absolute locations better than experimental uncertainties. However, our simulations also point out that the results of 2-D display experiments are not sufficient to determine the best set of parameters for the modeling of fragments separation in the second dimension and that additional detailed measurements of the mobility of a few sequences are necessary to achieve this goal. We hope that this work will help in establishing simulations as a powerful tool to optimize experimental conditions without having to perform a large number of preliminary experiments and to estimate whether 2-D DNA display is suited to identify a mutation or a genetic difference that is expected to exist between the genomes of closely related organisms. PMID:19862742

Florescu, Ana-Maria; Joyeux, Marc; Lafay, Bénédicte

2009-11-01

100

2-1/2-D electromagnetic modeling of nodular defects in high-power multilayer optical coatings  

SciTech Connect

Advances in the design and production of high damage threshold optical coatings for use in mirrors and polarizers have been driven by the design requirements of high-power laser systems such as the proposed 1.8-MJ National Ignition Facility (NIF) and the prototype 12- kJ Beamlet laser system. The present design of the NIF will include 192 polarizers and more than 1100 mirrors. Currently, the material system of choice for high-power multilayer optical coatings with high damage threshold applications near 1.06 {mu}m are e-beam deposited HfO{sub 2}/Si0{sub 2} coatings. However, the optical performance and laser damage thresholds of these coatings are limited by micron-scale defects and insufficient control over layer thickness. In this report, we will discuss the results of our 2-1/2-D finite-element time- domain (FDTD) EM modeling effort for rotationally-symmetric nodular defects in multilayer dielectric HR coatings. We have added a new diagnostic to the 2-1/2-D FDTD EM code, AMOS, that enables us to calculate the peak steady-state electric fields throughout a 2-D planar region containing a 2-D r-z cross-section of the axisymmetric nodular defect and surrounding multilayer dielectric stack. We have also generated a series of design curves to identify the range of loss tangents for Si0{sub 2} and HfO{sub 2} consistent with the experimentally determined power loss of the HR coatings. In addition, we have developed several methods to provide coupling between the EM results and the thermal-mechanical simulation effort.

Molau, N.E.; Brand, H.R.; Kozlowski, M.R.; Shang, C.C.

1996-07-01

101

Geometry in Medias Res  

ERIC Educational Resources Information Center

Geometry provides a natural window into what it is like to do mathematics. In the world of geometry, playful experimentation is often more fruitful than following a procedure, and logic plus a few axioms can open new worlds. Nonetheless, teaching a geometry course in a way that combines both rigor and play can be difficult. Many geometry courses…

Cukier, Mimi; Asdourian, Tony; Thakker, Anand

2012-01-01

102

Dynamic Geometry on WWW.  

ERIC Educational Resources Information Center

The first section of this paper on World Wide Web applications related to dynamic geometry addresses dynamic geometry and teaching, including the relationship between dynamic geometry and direct manipulation, key features of dynamic geometry environments, the importance of direct engagement of the learner using construction software for…

Kuntz, Gilles

103

MULTI2D - a computer code for two-dimensional radiation hydrodynamics  

NASA Astrophysics Data System (ADS)

Simulation of radiation hydrodynamics in two spatial dimensions is developed, having in mind, in particular, target design for indirectly driven inertial confinement energy (IFE) and the interpretation of related experiments. Intense radiation pulses by laser or particle beams heat high-Z target configurations of different geometries and lead to a regime which is optically thick in some regions and optically thin in others. A diffusion description is inadequate in this situation. A new numerical code has been developed which describes hydrodynamics in two spatial dimensions (cylindrical R-Z geometry) and radiation transport along rays in three dimensions with the 4? solid angle discretized in direction. Matter moves on a non-structured mesh composed of trilateral and quadrilateral elements. Radiation flux of a given direction enters on two (one) sides of a triangle and leaves on the opposite side(s) in proportion to the viewing angles depending on the geometry. This scheme allows to propagate sharply edged beams without ray tracing, though at the price of some lateral diffusion. The algorithm treats correctly both the optically thin and optically thick regimes. A symmetric semi-implicit (SSI) method is used to guarantee numerical stability. Catalogue identifier: AECV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AECV_v1_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.: 151?098 No. of bytes in distributed program, including test data, etc.: 889?622 Distribution format: tar.gz Programming language: C Computer: PC (32 bits architecture) Operating system: Linux/Unix RAM: 2 Mbytes Word size: 32 bits Classification: 19.7 External routines: X-window standard library (libX11.so) and corresponding heading files (X11/*.h) are required. Nature of problem: In inertial confinement fusion and related experiments with lasers and particle beams, energy transport by thermal radiation becomes important. Under these conditions, the radiation field strongly interacts with the hydrodynamic motion through emission and absorption processes. Solution method: The equations of radiation transfer coupled with Lagrangian hydrodynamics, heat diffusion and beam tracing (laser or ions) are solved, in two-dimensional axial-symmetric geometry (R-Z coordinates) using a fractional step scheme. Radiation transfer is solved with angular resolution. Matter properties are either interpolated from tables (equations-of-state and opacities) or computed by user routines (conductivities and beam attenuation). Restrictions: The code has been designed for typical conditions prevailing in inertial confinement fusion (ns time scale, matter states close to local thermodynamical equilibrium, negligible radiation pressure, …). Although a wider range of situations can be treated, extrapolations to regions beyond this design range need special care. Unusual features: A special computer language, called r94, is used at top levels of the code. These parts have to be converted to standard C by a translation program (supplied as part of the package). Due to the complexity of code (hydro-code, grid generation, user interface, graphic post-processor, translator program, installation scripts) extensive manuals are supplied as part of the package. Running time: 567 seconds for the example supplied.

Ramis, R.; Meyer-Ter-Vehn, J.; Ramírez, J.

2009-06-01

104

Design of [R-(Z)]-(+)-alpha-(methoxyimino)-1-azabicyclo[2.2.2]octane-3-acetonitri le (SB 202026), a functionally selective azabicyclic muscarinic M1 agonist incorporating the N-methoxy imidoyl nitrile group as a novel ester bioisostere.  

PubMed

Loss of cholinergic function is believed to be implicated in the cognitive decline associated with senile dementia of the Alzheimer type (SDAT). The disease is characterized by progressive loss of muscarinic receptors located on nerve terminals while postsynaptic muscarinic M1 receptors appear to remain largely intact. Muscarinic agonists acting directly on postsynaptic receptors offer the prospect of countering the cholinergic deficit in SDAT. This study describes a novel series of azabicyclic muscarinic agonists, which incorporate an oxime ether or modified oxime ether group as an ester bioisostere. Modification of the oxime ether function by the introduction of electron withdrawing groups led to the finding that the (Z)-N-methoxy imidoyl nitrile group serves as a stable methyl ester bioisostere. This culminated in the discovery of the quinuclidinyl N-methoxy imidoyl nitrile R-(+)-(Z)-5g which is a functionally selective muscarinic M1 partial agonist currently in phase III clinical trials for the treatment of SDAT. The selective profile of R-(+)-(Z)-5g can be rationalized in terms of the relative affinity of the compound at muscarinic receptor subtypes, the degree of agonist efficacy, and brain penetrancy. PMID:9435896

Bromidge, S M; Brown, F; Cassidy, F; Clark, M S; Dabbs, S; Hadley, M S; Hawkins, J; Loudon, J M; Naylor, C B; Orlek, B S; Riley, G J

1997-12-19

105

Interface evolution: water waves in 2-D  

Microsoft Academic Search

We study the free boundary evolution between two irrotational, incompressible and inviscid fluids in 2-D without surface tension. We prove local-existence in Sobolev spaces when, initially, the difference of the gradients of the pressure in the normal direction has the proper sign, an assumption which is also known as the Rayleigh-Taylor condition. The well-posedness of the full water wave problem

Antonio Cordoba; Diego Cordoba; Francisco Gancedo

2008-01-01

106

Interface evolution: Water waves in 2-D  

Microsoft Academic Search

We study the free boundary evolution between two irrotational, incompressible and inviscid fluids in 2-D without surface tension. We prove local existence in Sobolev spaces when, initially, the difference of the gradients of the pressure in the normal direction has the proper sign, an assumption which is also known as the Rayleigh–Taylor condition. The well-posedness of the full water wave

Antonio Córdoba; Diego Córdoba; Francisco Gancedo

2010-01-01

107

Anomalies in diluted 2D antiferromagnets  

NASA Astrophysics Data System (ADS)

The spectrum of quasi-two-dimensional quantum antiferromagnet diluted with spinless impurities is not ``protected'' at long-wavelengths but rather is overdamped at arbitrary concentration of impurities. Specific heat of diluted quasi-2D antiferromagnets is predicted to have a very anomalous behavior due to contribution from the localized states. Other anomalies in the dynamical properties are analyzed and a close agreement of our theoretical results with the recent neutron scattering data for the correlation length is demonstrated.

Chernyshev, Sasha; Chen, Yu-Chang; Castro Neto, Antonio H.

2002-03-01

108

Tomosynthesis imaging with 2D scanning trajectories  

NASA Astrophysics Data System (ADS)

Tomosynthesis imaging in chest radiography provides volumetric information with the potential for improved diagnostic value when compared to the standard AP or LAT projections. In this paper we explore the image quality benefits of 2D scanning trajectories when coupled with advanced image reconstruction approaches. It is intuitively clear that 2D trajectories provide projection data that is more complete in terms of Radon space filling, when compared with conventional tomosynthesis using a linearly scanned source. Incorporating this additional information for obtaining improved image quality is, however, not a straightforward problem. The typical tomosynthesis reconstruction algorithms are based on direct inversion methods e.g. Filtered Backprojection (FBP) or iterative algorithms that are variants of the Algebraic Reconstruction Technique (ART). The FBP approach is fast and provides high frequency details in the image but at the same time introduces streaking artifacts degrading the image quality. The iterative methods can reduce the image artifacts by using image priors but suffer from a slow convergence rate, thereby producing images lacking high frequency details. In this paper we propose using a fast converging optimal gradient iterative scheme that has advantages of both the FBP and iterative methods in that it produces images with high frequency details while reducing the image artifacts. We show that using favorable 2D scanning trajectories along with the proposed reconstruction method has the advantage of providing improved depth information for structures such as the spine and potentially producing images with more isotropic resolution.

Khare, Kedar; Claus, Bernhard E. H.; Eberhard, Jeffrey W.

2011-03-01

109

MAGNUM-2D computer code: user's guide  

SciTech Connect

Information relevant to the general use of the MAGNUM-2D computer code is presented. This computer code was developed for the purpose of modeling (i.e., simulating) the thermal and hydraulic conditions in the vicinity of a waste package emplaced in a deep geologic repository. The MAGNUM-2D computer computes (1) the temperature field surrounding the waste package as a function of the heat generation rate of the nuclear waste and thermal properties of the basalt and (2) the hydraulic head distribution and associated groundwater flow fields as a function of the temperature gradients and hydraulic properties of the basalt. MAGNUM-2D is a two-dimensional numerical model for transient or steady-state analysis of coupled heat transfer and groundwater flow in a fractured porous medium. The governing equations consist of a set of coupled, quasi-linear partial differential equations that are solved using a Galerkin finite-element technique. A Newton-Raphson algorithm is embedded in the Galerkin functional to formulate the problem in terms of the incremental changes in the dependent variables. Both triangular and quadrilateral finite elements are used to represent the continuum portions of the spatial domain. Line elements may be used to represent discrete conduits. 18 refs., 4 figs., 1 tab.

England, R.L.; Kline, N.W.; Ekblad, K.J.; Baca, R.G.

1985-01-01

110

Relative Affine Structure: Canonical Model for 3D From 2D Geometry and Applications  

Microsoft Academic Search

. We propose an affine framework for perspective views, capturedby a single extremely simple equation based on a viewer-centeredinvariant we call relative affine structure. Via a number of corollaries ofour main results we show that our framework unifies previous work --- includingEuclidean, projective and affine --- in a natural and simple way,and introduces new, extremely simple, algorithms for the tasks

Amnon Shashua; Nassir Navab

1996-01-01

111

A simplified presentation of the multigroup analytic nodal method in 2-D Cartesian geometry  

Microsoft Academic Search

The nodal diffusion algorithms used in many production reactor simulation codes are originating from a common ancestry developed in the 1970s, the analytic nodal method (ANM) of the QUANDRY code. However, this original presentation of the ANM is complex and makes difficult the calculation of the nodal coupling matrices. Moreover, QUANDRY is limited to two-energy groups and its generalization to

Alain Hébert

2008-01-01

112

Nonvolatile Particle Transport from Etched Surface in 2-D CCP Modeling  

NASA Astrophysics Data System (ADS)

Byproducts in etching processes are strongly linked to the incident ion flux on a wafer. We first discuss the radial uniformity of the ion flux incident on a substrate of the powered electrode as a function of reactor geometry. Nonvolatile particles ejected by etching( physical sputtering ) from the substrate will be the origin of an absorbed layer on the etched surface as well as the particle growth in the plasma. We investigate the nonvolatile particle transport in a 2-D capacitively coupled plasma( CCP ) under gas flow by using the relaxation continuum ( RCT ) model. We use a difussion equation to analize the nonvolatile particle transport with the gas flow. CCP is mainly maintained at 13.56 MHz with amplitude of 300 V at 100 mTorr in Ar. We also show a series of 2-D space distributions of CCP in various reactor geometry and the nonvolatile particle transport.

Hasebe, M.; Nakano, N.; Makabe, T.

1997-10-01

113

Resistivity of dilute 2D electrons in GaAs in the metal-insulator regime  

Microsoft Academic Search

We report resistivity measurements as a function of temperature in a dilute 2D electron system (2DES). The 2DES is in an undoped GaAs heterostructure processed in an field-effect transistor geometry. With this technique, high mobilities are observed over a wide range of densities (0.16 to 8.0 × 10^10 cm-2). For high densities, the temperature dependence of the resistivity is quantitatively

M. P. Lilly; J. L. Reno; J. A. Simmons; I. B. Spielman; J. P. Eisenstein; L. N. Pfeiffer; K. W. West; E. H. Hwang; S. Das Sarma

2003-01-01

114

Choice of a 2-D causal autoregressive texture model using information criteria  

Microsoft Academic Search

In the context of parametric modeling for image processing, we derive an estimation method for both the order and the parameters of 2-D causal autoregressive model with different geometries of support. Model parameters are estimated from a lattice representation, i.e. based on reflection coefficients. Lattice parameter estimation algorithms offer advantages compared to the Yule–Walker method: they do not require matrix

Olivier Alata; Christian Olivier

2003-01-01

115

Isogeometric analysis of 2D gradient elasticity  

NASA Astrophysics Data System (ADS)

In the present contribution the concept of isogeometric analysis is extended towards the numerical solution of the problem of gradient elasticity in two dimensions. In gradient elasticity the strain energy becomes a function of the strain and its derivative. This assumption results in a governing differential equation which contains fourth order derivatives of the displacements. The numerical solution of this equation with a displacement-based finite element method requires the use of C 1-continuous elements, which are mostly limited to two dimensions and simple geometries. This motivates the implementation of the concept of isogeometric analysis for gradient elasticity. This NURBS based interpolation scheme naturally includes C 1 and higher order continuity of the approximation of the displacements and the geometry. The numerical approach is implemented for two-dimensional problems of linear gradient elasticity and its convergence behavior is studied.

Fischer, Paul; Klassen, Markus; Mergheim, Julia; Steinmann, Paul; Müller, Ralf

2011-03-01

116

2-d Microcavities: Theory and Experiments  

Microsoft Academic Search

An overview is provided over the physics of dielectric microcavities with\\u000anon-paraxial mode structure; examples are microdroplets and edge-emitting\\u000asemiconductor microlasers. Particular attention is given to cavities in which\\u000atwo spatial degrees of freedom are coupled via the boundary geometry. This\\u000agenerally necessitates numerical computations to obtain the electromagnetic\\u000acavity fields, and hence intuitive understanding becomes difficult. However, as\\u000ain

Jens U. Nockel; Richard K. Chang

2004-01-01

117

Spectroscopy of N2D+ hyperfine structur  

NASA Astrophysics Data System (ADS)

The analysis of the fully resolved Nitrogen hyperfine structure of N2D+ (1-0) observed toward L183, together with laboratory measurements of the same molecular transition, allowed an accurate determination of the hyperfine constants of both outer and inner Nitrogen. In addition, accurate rotational and centrifugal distortion constants were derived from submillimeter-wave laboratory measurements. The Tables list calculated hyperfine frequencies of J+1<--J transitions, with J in the range 1-11, which occur in the millimeter- and submillimeter-wave region. (5 data files).

Dore, L.; Caselli, P.; Beninati, S.; Bourke, T.; Myers, P. C.; Cazzoli, G.

2003-11-01

118

2D Circular Square Well Applet  

NSDL National Science Digital Library

This simulation shows time-dependent 2D quantum bound state wavefunctions for a circular hard-walled potential. Position, momentum, angular momentum, and energy of the states can all be viewed, with phase shown with color. Eigentstates can be selected using the energy level diagram. Multiple-energy-eigenstate wavefunctions can be created through changes in the amplitude and phase of the basis states using spinors, or through the creation of Gaussian wavefunctions with the mouse. The quantum numbers of the states are shown.

Falstad, Paul

2004-05-17

119

2D Quantum Harmonic Oscillator Applet  

NSDL National Science Digital Library

This simulation shows time-dependent 2D quantum bound state wavefunctions for a harmonic oscillator potential. Position, momentum, angular momentum (for symmetric potentials), and energy of the states can all be viewed, with phase shown with color. Eigentstates can be selected using the energy level diagram. Multiple-energy-eigenstate wavefunctions can be created through changes in the amplitude and phase of the basis states using spinors, or through the creation of Gaussian, elliptical, or square wavefunctions with the mouse. The quantum numbers of the states are shown.

Falstad, Paul

2004-05-17

120

Another solution of 2D Ising model  

SciTech Connect

The partition function of the Ising model on a two-dimensional regular lattice is calculated by using the matrix representation of a Clifford algebra (the Dirac algebra), with number of generators equal to the number of lattice sites. It is shown that the partition function over all loops in a 2D lattice including self-intersecting ones is the trace of a polynomial in terms of Dirac matrices. The polynomial is an element of the rotation group in the spinor representation. Thus, the partition function is a function of a character on an orthogonal group of a high degree in the spinor representation.

Vergeles, S. N. [Russian Academy of Sciences, Landau Institute for Theoretical Physics (Russian Federation)], E-mail: vergeles@itp.ac.ru

2009-04-15

121

MPS simulation of 2-D spontaneous dynamic rupture propagation  

NASA Astrophysics Data System (ADS)

In order to carry out numerical simulations of seismic motions, it is important to model earthquake faults. Several numerical methods have been developed for simulating spontaneous dynamic rupture on earthquake faults, obeying a certain fracture criterion or friction law. In such simulations, boundary conditions of dislocation are usually set on the fault. Traction-at-split-node (TSN) method (Andrews[1973]) is one of the most popular methods. So far, this method has introduced a boundary condition of dislocation mainly into a finite difference (FD) or a finite element (FE) method. However, the regular grid-based FD method is not so suitable for modeling "curved winding faults". The FE method can treat complex geometry, but it usually takes time to construct fine meshes suitable for keeping numerical accuracy in the complex geometry. Actually, faults in the nature are not always flat and have some complexities in geometry. In order to remedy this disadvantage, we develop a new method which introduces a boundary condition of dislocation into Moving Particle Semi-implicit (MPS) method. The MPS method, which is one of particle methods such as the SPH (Smoothed-Particle Hydrodynamics) method, was newly developed by Koshizuka and his colleagues in 1996 in order to simulate non-compressive fluid. Then, it has been applied for simulating deformation and wave propagation in elastic media since Chikazawa (1999). For instance, Takekawa et al. (2008) carried out simulation of elastic wave propagation and succeeded in simulating Hopkinson's effect. The MPS method is based on Lagrangian formulation and an elastic body is described as an aggregate of particles. The government equations for the elastic medium are interpreted into interactions among these particles. These interactions are equivalent to those of normal and tangential springs. Each particle interacts with its neighboring particles using a local weighting function. Therefore, it is quite easy to deal with heterogeneity and complex geometry. In this respect, MPS is similar to SPH. However, the MPS method applies simplified differential operator models solely based on a local weighted averaging process without taking the gradient of a kernel function, whereas the differential operators are applied to spatially weighting kernels in the SPH method. In this study, we introduced a boundary condition of "2-D curved winding faults" into a MPS method referring to the TSN method. To be specific, we set "fault particles" at both sides of the fault. In these particles, "interaction force" in the MPS method was substituted for "restoring force" in the TNS method. In addition we used a slip-dependent friction law which has a linear slip-weakening friction coefficient with a characteristic slip distance. In the presentation, we show the details of implementation of TSN on the earthquake fault into the MPS method, and discuss the feasibility and the accuracy of the MPS method for a 2-D spontaneous dynamic propagation problem.

Sakamoto, T.; Hirahara, K.

2009-12-01

122

Geometry Formulas and Facts  

NSDL National Science Digital Library

Rewritten and updated excerpts from the 30th Edition of the CRC Standard Mathematical Tables and Formulas. Covers all of geometry, minus differential geometry. Very complete collection of definitions, formulas, tables and diagrams, divided into two- and three- dimensional geometry, and further into 16 subdivisions such as transformations, polygons, coordinate systems, isometries, polyhedra and spheres.

Levy, Silvio

2007-12-07

123

A 2-D ECG compression algorithm based on modified SPIHT  

Microsoft Academic Search

A new two-dimensional (2-D) Electrocardiogram (ECG) signal compression algorithm named 2D Modified Set Partitioning In Hierarchical Trees (2-D MSPIHT), which is based on the SPIHT algorithm, has been proposed in this paper. According to the two correlativity of ECG signal, an ECG signal is cut and aligned to form a 2-D data array, and then 2-D MSPIHT can be applied.

Zhelong Wang; Pengfu Zhu; Ying Chen

2008-01-01

124

Effects of Bias Frequency on 2D Image of Net Production Rate in Two Frequency CCP  

NASA Astrophysics Data System (ADS)

Two frequency capacitively-coupled plasma(2f-CCP) is a major processing tool for SiO2 etching. It is important to optimize the bias frequency for both a control of the ion energy on the wafer and a radial uniformity of 2f-CCP. Effect of bias frequency on 2D(r,z) profiles of axisymmetric 2f-CCP in CF_4/Ar at 25mTorr is investigated by time-resolved OES. Bias frequency in a range of 339kHz ~2.71MHz is applied to the 2f-CCP excited at 13.56MHz. For bias frequencies of 339kHz and 678kHz, the radial uniformity of the net excitation rate of probed-Ar(2p_1) is strongly affected by the bias voltage amplitude due to the excess excitation caused by high energy electrons at the central axis. Radial uniformity is improved for the bias frequency higher than 1.35MHz. The effect of bias frequency is also shown for the temporal variation of the net excitation rate during one bias period. The net rate changes by 50% at 1.35MHz, while it changes by 200% at 678kHz. The effect of secondary electrons from the bias electrode is suppressed in case of 1.35MHz by a temporal trapping. Optimization of the bias frequency above 1MHz becomes a key to enable the bimodal energy distribution of ion on the wafer surface and the radial uniformity of 2f-CCP. Results of VHF(100MHz) excitation and the detail of the sustaining mechanism of 2f-CCP during one RF period are also discussed.

Kitajima, T.; Fujita, T.; Mano, T.; Makabe, T.

1999-10-01

125

Astronomical Parallax 2D JS Model  

NSDL National Science Digital Library

The Astronomical Parallax 2D Javascript Model illustrates This simulation illustrates the phenomenon of parallax in astronomy. Parallax is the apparent displacement of an object relative to the background that is caused by the motion of the observer (rather than the motion of the object itself, or of the background). This simulation illustrates the parallax of an object in space that results from the Earth's rotational or orbital motions. The simulation has two different modes. The default is an Earth Rotation Mode. In this mode the simulation illustrates the parallax caused by Earth's rotation on its axis. The other mode for the simulation is Earth Orbit Mode. In this mode the simulation illustrates the parallax caused by Earth's orbit around the Sun. Now the observer moves along Earth's orbital path (shown as a blue circle with the orange Sun in the center). The bottom window shows the apparent motion of the object being observed. The Astronomical Parallax 2D JS Model was developed using the Easy Java Simulations (EJS) version 5. It is distributed as a ready-to-run html page and requires only a browser with JavaScript support.

Timberlake, Todd; Belloni, Mario

2013-09-03

126

Phase Transitions in 2-D Dusty Plasmas  

NASA Astrophysics Data System (ADS)

Dust grains suspended in plasma sheaths typically arrange into a two-dimensional layer. The interactions in the plane have been shown both theoretically and experimentally to be well-characterized by the screened Coulomb, or Yukawa, potential. The macroscopic size of the systems, as well as the fast time scales relative to the comparable colloid systems, allow for convenient comparison with both the simulation and theory of phase transitions in two-dimensional systems. We have performed molecular dynamics simulations of the 2-D Yukawa system, analysis of which leads to bounds on the melting transition in the coupling-screening parameter space. In our studies of melting, we employ the voronoi construction for the analysis of defects and the bond-orientational order parameter for the determination of long-range orientational order. We have also developed a combined radial/angular distribution function, useful for the anisotropic systems near melting. Our goal is to compare simulation results with the competing dislocation-mediated and grain-boundary-mediated theories of 2-D melting in a parameter regime typical of dusty plasmas.

Jones, Christopher

2005-10-01

127

Passive Scalar in 2D Turbulence  

NASA Astrophysics Data System (ADS)

We examined the behavior of a passive scalar in a 2D turbulent flow and confirm the so-called Batchelor scaling. For large r, the second order structure function S2(r) = <(?(x+r) - ?(x))^2> ˜ log(r). For small r, S2(r) ˜ r^2. The logarithmic dependence of S2(r) is consistent with a power spectrum that goes as the inverse power of k, the wavenumber. These experiments are performed using a falling soap film as the 2D turbulent system and various colored dyes for the passive scalar, which is injected at a point. The decaying turbulence is generated using a comb oriented perpendicular to the film. It does not appear to matter whether the dye is injected above or below the comb. The measurements were made in the Eulerian frame at a single point. Time is then replaced by distance using the Taylor frozen turbulence hypothesis. The structure function is determined from the correlation function, which is calculated using a photon correlation scheme. The passive scalar measurements are compared with the behavior of thickness fluctuations in the soap film, which is another random variable.

Cerbus, Rory; Goldburg, Walter

2011-11-01

128

2-D or not 2-D, that is the question: A Northern California test  

SciTech Connect

Reliable estimates of the seismic source spectrum are necessary for accurate magnitude, yield, and energy estimation. In particular, how seismic radiated energy scales with increasing earthquake size has been the focus of recent debate within the community and has direct implications on earthquake source physics studies as well as hazard mitigation. The 1-D coda methodology of Mayeda et al. has provided the lowest variance estimate of the source spectrum when compared against traditional approaches that use direct S-waves, thus making it ideal for networks that have sparse station distribution. The 1-D coda methodology has been mostly confined to regions of approximately uniform complexity. For larger, more geophysically complicated regions, 2-D path corrections may be required. The complicated tectonics of the northern California region coupled with high quality broadband seismic data provides for an ideal ''apples-to-apples'' test of 1-D and 2-D path assumptions on direct waves and their coda. Using the same station and event distribution, we compared 1-D and 2-D path corrections and observed the following results: (1) 1-D coda results reduced the amplitude variance relative to direct S-waves by roughly a factor of 8 (800%); (2) Applying a 2-D correction to the coda resulted in up to 40% variance reduction from the 1-D coda results; (3) 2-D direct S-wave results, though better than 1-D direct waves, were significantly worse than the 1-D coda. We found that coda-based moment-rate source spectra derived from the 2-D approach were essentially identical to those from the 1-D approach for frequencies less than {approx}0.7-Hz, however for the high frequencies (0.7{le} f {le} 8.0-Hz), the 2-D approach resulted in inter-station scatter that was generally 10-30% smaller. For complex regions where data are plentiful, a 2-D approach can significantly improve upon the simple 1-D assumption. In regions where only 1-D coda correction is available it is still preferable over 2-D direct wave-based measures.

Mayeda, K; Malagnini, L; Phillips, W S; Walter, W R; Dreger, D

2005-06-06

129

Numerical tools for the stability analysis of 2D flows: application to the two- and four-sided lid-driven cavity  

Microsoft Academic Search

This paper deals with the numerical study of bifurcations in the two-dimensional (2D) lid-driven cavity (LDC). Two specific geometries are considered. The first geometry is the two-sided non-facing (2SNF) cavity: the velocity is imposed on the upper and the left side of the cavity. The second geometry is the four-sided (4S) cavity where all the sides have a prescribed motion.

J M Cadou; Y Guevel; G Girault

2012-01-01

130

DETACH: an Excel spreadsheet to simulate 2-D cross sections of detachment folds  

NASA Astrophysics Data System (ADS)

Structural geologists now recognize detachment folds as fundamental structural features in many contractional settings. Several two-dimensional geometric and kinematic models exist to describe the development of such detachment folds; however, most are not available in a computer-based format that permits the forward-modeling and graphical representation of the detachment fold geometry. We developed DETACH, a Microsoft Excel™ spreadsheet, to construct simple cross sections of detachment folds using published geometric and kinematic models. DETACH allows users to assess the range of possible fold geometries and detachment depths that can be constructed using a prescribed set of fold kinematics, and to quickly evaluate and select a best-fit kinematic model for folds of known geometry. We illustrate DETACH's capabilities by modeling a two-dimensional cross section of a natural detachment fold and by constructing pseudo-three-dimensional models of detachment fold terminations with the assistance of Geosec2D™ and Gocad™ structural modeling software.

Wilkerson, M. Scott; Wilson, Joshua M.; Poblet, Josep; Fischer, Mark P.

2004-11-01

131

Simple 2-D navigation for wheeled vehicles  

SciTech Connect

This paper describes a simple algorithm to perform navigation in a two-dimensional world model. The algorithm utilizes a simple geometric approach which is first applied to a bicycle. The equations are then expeanded to apply to 3- and 4-wheeled vehicles with ''conventional'' steering mechanism (such as the Ackerman steering geometry in the 4-wheeled case). Calculations for omnidirectional robots which utilize differential odometry and differential drive are described as well. Practical considerations and sources of error are discussed, as are possible extensions of this method to a three-dimensional world model. 5 refs., 8 figs.

Klarer, P.R.

1988-01-01

132

Simple 2-D navigation for wheeled vehicles  

SciTech Connect

This paper describes a simple algorithm to perform navigation in a two-dimensional world model. The algorithm utilizes a simple geometric approach which is first applied to a bicycle. The equations are then expanded to apply to 3- and 4-wheeled vehicles with ''conventional'' steering mechanisms (such as the Ackerman steering geometry in the 4-wheeled case). Calculations for omnidirectional robots which utilize differential odometry and differential drive are described as well. Practical considerations and sources of error are discussed, as are possible extensions of this method to a three-dimensional world model. 5 refs., 8 figs.

Klarer, P.R.

1988-04-01

133

2D axisymmetric analysis of SRM ignition transient  

NASA Astrophysics Data System (ADS)

To analyze ignition transient of Space Shuttle solid rocket motor, a transient two-dimensional numerical model based on turbulent compressible Navier-Stokes equations in a generalized coordinate system was developed. One-dimensional numerical models (Peretz et al., 1973; Han, 1992; Pardue and Han, 1992) with empirical correlations data obtained from steady turbulent boundary layer flows agrees reasonably well with test rocket data by adjusting a few parameters. However, a 1D model can not provide a physical insight into the complex multidimensional thermal fields and flowfields in the chamber and the converging-diverging rocket nozzle. As an interim step, a 2D model was developed and compared with test data. A modified version of SIMPLE algorithm was used for the numerical model, and the standard k-epsilon model with a wall function was used for turbulence closure. Transient flowfields and thermal fields in the combustion chamber and the attached nozzle were obtained for a selected rocket geometry and propellant. Transient behaviors of the flow and thermal fields were analyzed, and were found to be in good agreement with physical expectations.

Bai, S. D.; Han, Samuel S.; Pardue, B. A.

1993-06-01

134

2D Fluidization of Nanomaterials by Biomimetic Membranes  

NASA Astrophysics Data System (ADS)

The last decade has seen much progress in the synthesis and manufacturing of a large variety of nanometer sized particles of different materials, geometries and properties. If they can be assembled into larger structures, these manmade nano-objects are posed to be the ``atoms'' and ``molecules'' of new materials. In order to facilitate their dynamic rearrangements we have developed a method that uses material specific binding peptides to anchor nano-objects to lipids in supported bilayers (SLB). In this study we use single walled carbon nanotubes (CNT) with a mean length of 1 micrometer as model of a potential nano-building block. By fluorescently labeling CNTs we are able to use video-microscopy to investigate the dynamic behavior of membrane anchored CNTs. We show that the 2D fluidity of the lipid membrane can be successfully templated on the CNTs and that they stay laterally mobile while being confined to a plane. Furthermore, the dependence of CNT mobility on specific binding stoichiometries is discussed.

Kelly, Kathleen; Forstner, Martin

2012-02-01

135

2D Fluidization of Nanomaterials by Biomimetic Membranes  

NASA Astrophysics Data System (ADS)

The last decade has seen much progress in the synthesis and manufacturing of a large variety of nanometer sized particles of different materials, geometries and properties. If they can be assembled into larger structures, these manmade nano-objects are posed to be the ``atoms'' and ``molecules'' of new materials. In order to facilitate their dynamic rearrangements we have developed a method that uses material specific binding peptides to anchor nano-objects to lipids in supported bilayers (SLB). In this study we use single walled carbon nanotubes (CNT) with a mean length of 1 micrometer as model of a potential nano-building block. By fluorescently labeling CNTs we are able to use video-microscopy to investigate the dynamic behavior of membrane anchored CNTs. We show that the 2D fluidity of the lipid membrane can be successfully templated on the CNTs and that they stay laterally mobile while being confined to a plane. Furthermore, the dependence of CNT mobility on specific binding stoichiometries is discussed.

Kelly, Kathleen; Forstner, Martin

2013-03-01

136

Numerical models of 2-D and 3-D geophysical convection  

SciTech Connect

A suite of computational models has been developed which simulate thermal/chemical convection over a wide range of Rayleigh numbers both in 2-D annular and 3-D Cartesian geometries, for small Reynolds number flow, and a variety of boundary conditions. These simulators are revealing the patterns of convection that may occur in the earth, from mantle scale down to more localized regions such as mid-ocean spreading centers, on down to the scale of magma chambers. Features such as surface plates, variable viscosity and chemical buoyancy can have a dramatic impact on convective patterns compared to those seen in simple, constant property, free or fixed surface systems. In most cases, the nonlinear dynamics of these systems derive from thermal and chemical forces, rather than inertial. These models can be used to study general features and dynamics of convecting viscous fluids, and can also be used to constrain possible explanations for geophysical observations such as heat flow, gravity, topography, plate speeds, and isotopic distributions. Computational resources have reached a level at which numerical solutions of complex processes are feasible.

Travis, B.J.

1990-01-01

137

Steady 2d Detonations and the DSD Theory  

NASA Astrophysics Data System (ADS)

The simplest Detonation Shock Dynamics (DSD) theory assumes that the detonation normal velocity D is determined by the total front curvature k and that the edge angle, the angle between the normal to the front and the explosive edge, has a unique value for each explosive and confinement material combination. This model has been used to derive the ordinary differential equations describing steady 2D detonation front shapes in slab, cylinder and rib geometries. It was found that one solution (a steady detonation front shape) corresponds to several combinations of the confinement material and the defining charge dimension (slab thickness, cylinder radius, or inner rib radius). Comparing experimental data for these combinations and analyzing the shape difference at the edge provide valuable information on the D(k) relation at low D corresponding to forced detonation regimes. The analysis of the experimental data on IHE ribs detonation indicates that as D decreases k tends to a limit of about 0.05 1/mm, i.e., of the order of reciprocal critical diameter. This revises the present view of the D(k) relation making the DSD theory consistent with the experimentally observed critical diameter.

Lubyatinsky, Sergey N.

2005-07-01

138

Determination of the Effective Properties of Thermal Spray Coatings Using 2D and 3D Models  

NASA Astrophysics Data System (ADS)

Models, which are developed to determine the effective properties of thermal spray coatings, require the material properties of each constituent of the coating as well as the information about the spatial positions and the geometries of these constituents as input parameters. The complex microstructure of thermally sprayed Yttria-stabilized zirconia (YSZ) coatings consists of irregular voids which are distributed non-uniformly in the coating. It is a common practice in the literature to employ two-dimensional (2D) cross-sectional images of the coatings to derive the geometrical model of the microstructure and conduct the simulations in 2D. In the context of this study, contrary to the 2D approach, a new three-dimensional (3D) reconstruction approach has been developed to model the microstructure of thermally sprayed coatings in 3D. The effective properties of an YSZ coating have been calculated by means of asymptotic homogenization and virtual testing methods. The results of the models, which have been conducted in 2D and 3D, are compared with each other. Finally, the capabilities of these methods with respect to the modeling approach (in 3D and in 2D) are analyzed on the basis of reference measurements.

Bobzin, K.; Kopp, N.; Warda, T.; Öte, M.

2012-12-01

139

Falling Body On Rotating Earth 2D  

NSDL National Science Digital Library

The EJS Falling Body On Rotating Earth 2D model illustrates the trajectory of an object dropped from rest (relative to the rotating Earth) from a point above Earth's equator. The user can set the initial height of the object above (or below) the Earth's surface, as well as the rotational speed of Earth. The motion of the object can be viewed from an inertial reference frame, or from a frame that rotates with the Earth (illustrating the effects of the so-called "Coriolis force"). The simulation can be made to stop when the object hits Earth's surface, or it can allow the object to move through the Earth. The user can select from a variety of options that control the gravitational and resistive forces acting on the object as it falls. The simulation can also generate a plot of the object's longitude (initially assumed to be zero) as a function of time.

Timberlake, Todd

2012-07-26

140

Vortices in the 2D Kuramoto model  

NASA Astrophysics Data System (ADS)

We study the synchronization of oscillators in 2D lattices with nearest neighbor coupling. The boundaries between synchronized domains are due to the motion of vortices. Since the phase winds by 2pi around a vortex, it generates 2pi phase slips between oscillators across its path. Thus, the synchronization behavior of the system can be viewed in terms of the production, movement, and annihilation of vortex pairs. Although the Kuramoto model is nonlinear, we show how to use the steady state solution of the linearized model to predict where the vortices are produced and how they move. We also study vortex density as a function of system size and coupling. This vortex approach may lead to an analytical understanding of why the lower critical dimension for macroscopic entrainment is 2.

Lee, Tony; Tam, Heywood; Refael, Gil; Rogers, Jeffrey; Cross, Michael

2010-03-01

141

A 2D driven 3D vessel segmentation algorithm for 3D digital subtraction angiography data.  

PubMed

Cerebrovascular disease is among the leading causes of death in western industrial nations. 3D rotational angiography delivers indispensable information on vessel morphology and pathology. Physicians make use of this to analyze vessel geometry in detail, i.e. vessel diameters, location and size of aneurysms, to come up with a clinical decision. 3D segmentation is a crucial step in this pipeline. Although a lot of different methods are available nowadays, all of them lack a method to validate the results for the individual patient. Therefore, we propose a novel 2D digital subtraction angiography (DSA)-driven 3D vessel segmentation and validation framework. 2D DSA projections are clinically considered as gold standard when it comes to measurements of vessel diameter or the neck size of aneurysms. An ellipsoid vessel model is applied to deliver the initial 3D segmentation. To assess the accuracy of the 3D vessel segmentation, its forward projections are iteratively overlaid with the corresponding 2D DSA projections. Local vessel discrepancies are modeled by a global 2D/3D optimization function to adjust the 3D vessel segmentation toward the 2D vessel contours. Our framework has been evaluated on phantom data as well as on ten patient datasets. Three 2D DSA projections from varying viewing angles have been used for each dataset. The novel 2D driven 3D vessel segmentation approach shows superior results against state-of-the-art segmentations like region growing, i.e. an improvement of 7.2% points in precision and 5.8% points for the Dice coefficient. This method opens up future clinical applications requiring the greatest vessel accuracy, e.g. computational fluid dynamic modeling. PMID:21908904

Spiegel, M; Redel, T; Struffert, T; Hornegger, J; Doerfler, A

2011-09-09

142

No-hair conjecture in 2D dilaton supergravity.  

National Technical Information Service (NTIS)

Two dimensional dilaton gravity and supergravity are studied following Hamiltonian methods. The structure of constraints of 2D dilaton gravity and the 2D dilaton supergravity theory is discussed taking the square root of the bosonic constraints. The equat...

J. Gamboa Y. Georgelin

1993-01-01

143

Topology and Geometry Software  

NSDL National Science Digital Library

The Topology and Geometry Software site provides downloads for games and interactive simulations. These help the user to understand finitely infinite systems. Many are available in multiple languages.

Weeks, Jeff

2009-06-15

144

2-D phase contrast imaging of turbulence structure on LHD  

Microsoft Academic Search

CO2 laser-based phase contrast imaging (PCI) equipped with a 6 by 8 element two-dimensional (2-D) array of photoconductors is used on the large helical device (LHD) for studying plasma density microfluctuations. Observing 2-D structures of turbulence and strong magnetic shear along the viewing line on LHD permit conversion of a 2-D-PCI image to a 2-D picture of the radial distribution

Leonid N. Vyacheslavov; K. Tanaka; A. L. Sanin; K. Kawahata; C. Michael; T. Akiyama

2005-01-01

145

Improvements in the computerized analysis of 2D INADEQUATE spectra  

Microsoft Academic Search

Two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy has become a prominent technique for the determination of molecular structure. The 2D version of the incredible natural abundance double quantum transfer experiment (INADEQUATE) is one of the most elegant 2D structure elucidation techniques. The carbon skeleton of a molecule can be determined by using the powerful 2D INADEQUATE experiment, but the method

Reinhard. Dunkel; Charles L. Mayne; Ronald J. Pugmire; David M. Grant

1992-01-01

146

COMESH - A Corner Mesh Finite Difference Code to Solve Multigroup Diffusion Equations in Multidimensions.  

National Technical Information Service (NTIS)

A code called COMESH based on corner mesh finite difference scheme has been developed to solve multigroup diffusion theory equations. One can solve 1-D, 2-D or 3-D problems in Cartesian geometry and 1-D (r) or 2-D (r-z) problem in cylindrical geometry. On...

V. Jagannathan A. K. Kulkarni R. P. Jain

1987-01-01

147

2-D fiberoptic scanning microdisplay system  

NASA Astrophysics Data System (ADS)

This paper details the improvement of image quality of the previously developed piezoelectric driven 2D Optical Display system using an optical fiber waveguide. The current display system is able to produce a desired image (FPGA input) via the oscillation of a micro-fabricated cantilever waveguide or an optical fiber "pixel" driven by two piezoelectric actuators in perpendicular arrangements; however, the image produced is blurred and unstable. To sharpen the image and allow a more detailed image to be displayed, a more refined output "pixel" is needed. To obtain such a "pixel", optical fibers with a tapered tip and metallic deposits is to be used on the output end. The use of the tapered fiber as a waveguide reduces the light that was being misguided by the cladding of the fiber and produces a finer "pixel" at each point of the image, reducing the blurriness of the displayed image. A closed loop feedback control was also added because the existing system requires manual frequency calibration to find the proper frequency to display the image after each system reset. The added control will find the proper frequency by matching the input image and the output image via image recognition coding in MATLAB and adjust the system to the optimal display frequency at the initialization of the system.

Wang, Wei-Chih; Tsui, Chi-Leung; Lau, Fai-Hon; Perez, Alex; Chuang, Wei-Ching

2008-04-01

148

Interstitials in 2D colloidal crystals  

NASA Astrophysics Data System (ADS)

Point defects in crystalline solids are important in many areas of condensed matter physics, ranging from the mechanical properties of metals, to supersolidity in quantum solids, and most recently the magnetic properties of graphene. A key question to point defects is how they diffuse in the crystalline lattice. Colloidal crystals provide a perfect model system for studying the dynamics of point defects, since the kinetic pathways of diffusion can be identified in direct real-time video imaging experiments. Here we report an experimental study of another type of point defects: interstitials. We found that interstitial diffusion in a 2D colloidal crystal is also dominated by a dislocation pair unbinding-binding process. Similar to vacancies, interstitial diffusion exhibits strong memory effects. However, the contrast lies in the observation that the interstitials, as quasi-particles, diffuse faster than vacancies. We propose that higher diffusion constant of the interstitials is a result of the suppression of the Peierls barrier for the edge dislocations by the excess strain created by the extra particle(s). This work was supported by NSF-DMR.

Yu, Lichao; Kim, Sungcheol; Pertsinidis, Alexandros; Ling, Xinsheng

2013-03-01

149

Collective Variable Range Hopping in 2-D  

NASA Astrophysics Data System (ADS)

We have measured resistance v. temperature in ultra-thin quench-condensed metal films. Far from the metal-insulator transition, in the early stages of growth, all of our films exhibit the exponential form R?exp(T_o/T)^x, with x=0.8± 0.03. Due to a logarithmic interaction between electrons in 2-D, we can map a theory for vortex hopping in a superconductor by Fisher et al.(M. P. A. Fisher et. al.), Phys. Rev. Lett. 66, 2931 (1991). onto the problem of electron hopping. The long-range interaction results in a reduction of energy for a single hop if surrounding electrons also hop. If the number of electrons participating in this collective hop are contained in an area whose radius is the hopping distance, the theory gives x=4/5, in good agreement with our data. Preprint.

Grupp, Daniel E.; Martinez, G.; Markovic, N.; Mack, A. M.; Glazman, L.; Goldman, A. M.

1998-03-01

150

Interactive Geometry Dictionary: Areas in Geometry  

NSDL National Science Digital Library

The applets in this Interactive Geometry Dictionary (IGD) will allow students an opportunity to explore finding the area of some common shapes. The applets demonstrate how to find the area of a triangle using the area of a parallelogram, which in turn can be found using the area of a rectangle. This tool also supports the lesson "What's My Area" cataloged separately.

2011-01-01

151

Geometry Here, Geometry There, Geomerty is EVERYWHERE!  

NSDL National Science Digital Library

See if you know your geometry by using coordinate planes! GAME 1 Space Boy To The Rescue! See if you can fly through space using coordinate pairs if you dare! Directions: Double click on the space astronaut on the right hand side of the screen. Your astronaut should ...

Tiller, Miss

2012-02-05

152

Analysis of composite EM scattering based on accurate geometry modeling  

Microsoft Academic Search

An approach to studying composite EM scattering from 2-D rough surface and half-buried 3-D target is proposed in this paper, from accurate geometry modeling to RCS analysis. First, two dimensional rough surface is simulated with spectral method, which then is converted into a continuous curved surface through inverse engineering. Target model and rough surface model are combined together to be

Jie Li; Qiong He; Lixin Guo; Bing Wei

2011-01-01

153

The virtual geometry model  

Microsoft Academic Search

The Virtual Geometry Model (VGM) was introduced at CHEP in 2004 [1], where its concept, based on the abstract interfaces to geometry objects, has been presented. Since then, it has undergone a design evolution to pure abstract interfaces, it has been consolidated and completed with more advanced features. Currently it is used in Geant4 VMC for the support of TGeo

I. Hrivnácová; B. Viren

2008-01-01

154

Introduction to combinatorial geometry  

Microsoft Academic Search

The combinatorial geometry package as used in many three-dimensional multimedia Monte Carlo radiation transport codes, such as HETC, MORSE, and EGS, is becoming the preferred way to describe simple and complicated systems. Just about any system can be modeled using the package with relatively few input statements. This can be contrasted against the older style geometry packages in which the

T. A. Gabriel; M. B. Emmett

1985-01-01

155

Geometry + Technology = Proof  

ERIC Educational Resources Information Center

|Several interactive geometry software packages are available today to secondary school teachers. An example is The Geometer's Sketchpad[R] (GSP), also known as Dynamic Geometry[R] software, developed by Key Curriculum Press. This numeric based technology has been widely adopted in the last twenty years, and a vast amount of creativity has been…

Lyublinskaya, Irina; Funsch, Dan

2012-01-01

156

Geometry + Technology = Proof  

ERIC Educational Resources Information Center

Several interactive geometry software packages are available today to secondary school teachers. An example is The Geometer's Sketchpad[R] (GSP), also known as Dynamic Geometry[R] software, developed by Key Curriculum Press. This numeric based technology has been widely adopted in the last twenty years, and a vast amount of creativity has been…

Lyublinskaya, Irina; Funsch, Dan

2012-01-01

157

Geometry of multihadron production  

SciTech Connect

This summary talk only reviews a small sample of topics featured at this symposium: Introduction; The Geometry and Geography of Phase space; Space-Time Geometry and HBT; Multiplicities, Intermittency, Correlations; Disoriented Chiral Condensate; Deep Inelastic Scattering at HERA; and Other Contributions.

Bjorken, J.D.

1994-10-01

158

Euclidean Geometry via Programming.  

ERIC Educational Resources Information Center

Describes the Plane Geometry System computer software developed at the Educational Computer Systems laboratory in Sofia, Bulgaria. The system enables students to use the concept of "algorithm" to correspond to the process of "deductive proof" in the development of plane geometry. Provides an example of the software's capability and compares it to…

Filimonov, Rossen; Kreith, Kurt

1992-01-01

159

'Brukin2D': a 2D visualization and comparison tool for LC-MS data  

PubMed Central

Background Liquid Chromatography-Mass Spectrometry (LC-MS) is a commonly used technique to resolve complex protein mixtures. Visualization of large data sets produced from LC-MS, namely the chromatogram and the mass spectra that correspond to its compounds is the focus of this work. Results The in-house developed 'Brukin2D' software, built in Matlab 7.4, which is presented here, uses the compound data that are exported from the Bruker 'DataAnalysis' program, and depicts the mean mass spectra of all the chromatogram compounds from one LC-MS run, in one 2D contour/density plot. Two contour plots from different chromatograph runs can then be viewed in the same window and automatically compared, in order to find their similarities and differences. The results of the comparison can be examined through detailed mass quantification tables, while chromatogram compound statistics are also calculated during the procedure. Conclusion 'Brukin2D' provides a user-friendly platform for quick, easy and integrated view of complex LC-MS data. The software is available at .

Tsagkrasoulis, Dimosthenis; Zerefos, Panagiotis; Loudos, George; Vlahou, Antonia; Baumann, Marc; Kossida, Sophia

2009-01-01

160

Creation of a standardized geometry of the human nasal cavity.  

PubMed

A novel, standardized geometry of the human nasal cavity was created by aligning and processing 30 sets of computed tomography (CT) scans of nasal airways of healthy subjects. Digital three-dimensional (3-D) geometries of the 60 single human nasal cavities (30 right and 30 mirrored left cavities) were generated from the CT scans and measurements of physical parameters of each single nasal cavity were performed. A methodology was developed to scale, orient, and align the nasal geometries, after which 2-D digital coronal cross-sectional slices were generated. With the use of an innovative image processing algorithm, median cross-sectional geometries were created to match median physical parameters while retaining the unique geometric features of the human nasal cavity. From these idealized 2-D images, an original 3-D standardized median human nasal cavity was created. This new standardized geometry was compared against the original geometries of all subjects as well as limited existing data from the literature. The new model has potential for use as a geometric standard in future experimental and numerical studies of deposition of inhaled aerosols, as well as for use as a reference during diagnosis of unhealthy patients. The specific procedure developed could also be applied to build standard nasal geometries for different identifiable groups within the larger population. PMID:19131483

Liu, Y; Johnson, M R; Matida, E A; Kherani, S; Marsan, J

2009-01-08

161

Fosite: 2D advection problem solver  

NASA Astrophysics Data System (ADS)

Fosite implements a method for the solution of hyperbolic conservation laws in curvilinear orthogonal coordinates. It is written in Fortran 90/95 integrating object-oriented (OO) design patterns, incorporating the flexibility of OO-programming into Fortran 90/95 while preserving the efficiency of the numerical computation. Although mainly intended for CFD simulations, Fosite's modular design allows its application to other advection problems as well. Unlike other two-dimensional implementations of finite volume methods, it accounts for local conservation of specific angular momentum. This feature turns the program into a perfect tool for astrophysical simulations where angular momentum transport is crucial. Angular momentum transport is not only implemented for standard coordinate systems with rotational symmetry (i.e. cylindrical, spherical) but also for a general set of orthogonal coordinate systems allowing the use of exotic curvilinear meshes (e.g. oblate-spheroidal). As in the case of the advection problem, this part of the software is also kept modular, therefore new geometries may be incorporated into the framework in a straightforward manner.

Illenseer, Tobias

2012-04-01

162

A Comparison of 2D to 3D Hydro Simulations of Asteroid Mitigation by a Strong Surface Explosion  

NASA Astrophysics Data System (ADS)

Disruption of a potentially hazardous object (PHO) by an energetic surface or subsurface burst is considered as one possible method of impact-hazard mitigation. This technique of employing surface or subsurface explosions has been popularized in the media but is probably one of the lower priority deflection/disruption methods, unless the warning time is short. In all of our current simulation we use realistic RADAR shape models for the initial geometry, not merely spherical objects. The non-sphericity of the geometry is very important in the resultant shock hydrodynamic evolution. This work is a follow-on to previous 2D simulations with the RAGE hydrocode to simulate the imparted momentum as a function of depth-of-burial (DOB) on a non-spherical "rubble pile" composition. Specifically, here, we have started a full 3D simulation of a 1 Mt surface explosion on a porous (~40% porosity) "rubble pile" model in the shape of asteroid 25143 Itokawa. This simulation has progressed far enough to start comparisons between the 2D and 3D runs of this model. There are significant changes in the 3D geometry that reduce the momentum imparted to the asteroid in these RAGE simulations. I will discuss this set of simulations, give some background results from previous 2D simulations and indicate the differences between 2D and 3D simulations.

Weaver, R.; Dearholdt, W.

2011-12-01

163

Simulation of Solar Particle Dropouts in Slab+2D Spherical Harmonic Magnetic Fields  

NASA Astrophysics Data System (ADS)

The rapid changes in the intensity of solar energetic particles (SEPs) called dropouts, in which the intensity appears and disappears repeatedly, were measured by the ACE spacecraft for impulsive solar flare events and represent the filamentation of the particle distribution. We have explained these features using computer simulations. We evaluate the particle trajectories in slab + 2D spherical harmonic magnetic fields using the fundamental Newton-Lorentz equations in spherical geometry. We simulate the motion of charged particles at different energies in the same magnetic field, which shows that the low energy particles closely follow the slab + 2D spherical harmonic magnetic fields and exhibit dropout features. These features remain and the distribution is even more compact for high energy particles at about 1 AU. Partially supported by NSF SHINE ATM-0752135 and NASA Heliophysics Theory Program NNX08A147G.

Tooprakai, P.; Ruffolo, D. J.; Matthaeus, W. H.

2011-12-01

164

Grain Boundary Cohesive Laws as a Function of Geometry  

NASA Astrophysics Data System (ADS)

Cohesive laws are stress-strain curves used in finite element calculations to describe the debonding of interfaces such as grain boundaries. It would be convenient to describe cohesive laws as a function of the parameters needed to describe the grain boundary geometry; two parameters in 2D and 5 parameters in 3D. However, we find that the cohesive law is not a smooth function of these parameters. In fact, it is discontinuous at all geometries for which the two grains have repeat distances that are rational with respect to one another. Using atomistic simulations, we extract cohesive laws of grain boundary fracture in 2D with a Lennard-Jones potential for all possible geometries which can be simulated within periodic boundary conditions with a maximum box size. We connect the atomistic result to analytic calculations of fracture toughness as a function of dislocation density.

Coffman, Valerie; Sethna, James

2006-03-01

165

Expansion, geometry, and gravity  

NASA Astrophysics Data System (ADS)

In general-relativistic cosmological models, the expansion history, matter content, and geometry are closely intertwined. In this brief paper, we clarify the distinction between the effects of geometry and expansion history on the luminosity distance. We show that the cubic correction to the Hubble law, measured recently with high-redshift supernovae, is the first cosmological measurement, apart from the cosmic microwave background, that probes directly the effects of spatial curvature. We illustrate the distinction between geometry and expansion with a toy model for which the supernova results already indicate a curvature radius larger than the Hubble distance.

Caldwell, Robert R.; Kamionkowski, Marc

2004-09-01

166

Native American Geometry  

NSDL National Science Digital Library

A physical, proportional geometry that originates from the simple circle. A growing body of architectural and iconographic evidence suggests this geometry was a relatively common tradition and has been practiced for at least 2000 years. The site is divided into four areas: Foundations, Anthropology, Designs, and Education; it introduces this two-dimensional non-random geometry in a connect-the-point format, exploring the intellectual and cultural implications of pre-Columbian geometric traditions in the New World. It also provides a list of European mathematical ramifications of the designs.

Forum, Math; Hardaker, Chris

2000-01-01

167

2D gasdynamic simulation of the kinetics of an oxygen-iodine laser with electric-discharge generation of singlet oxygen  

SciTech Connect

The kinetic processes occurring in an electric-discharge oxygen-iodine laser are analyzed with the help of a 2D (r, z) gasdynamic model taking into account transport of excited oxygen, singlet oxygen, and radicals from the electric discharge and their mixing with the iodine-containing gas. The main processes affecting the dynamics of the gas temperature and gain are revealed. The simulation results obtained using the 2D model agree well with the experimental data on the mixture gain. A subsonic oxygen-iodine laser in which singlet oxygen is generated by a 350 W transverse RF discharge excited in an oxygen flow at a pressure P = 10 Torr and the discharge tube wall is covered with mercury oxide is simulated. The simulated mixing system is optimized in terms of the flow rate and the degree of preliminary dissociation of the iodine flow. The optimal regime of continuous operation of a subsonic electric-discharge oxygen-iodine laser is found.

Chukalovsky, A. A.; Rakhimova, T. V.; Klopovsky, K. S.; Mankelevich, Yu. A.; Proshina, O. V. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

2011-03-15

168

Digit ratio (2D:4D) in Klinefelter's syndrome.  

PubMed

The ratio of second to fourth digit length (2D:4D) is a correlate of prenatal testosterone. High 2D:4D is associated with low prenatal testosterone, and reduced sensitivity to testosterone. Klinefelter's syndrome (KS; 47 XXY) affects the endocrine system, such that low testosterone levels are found in KS foetuses, new-borns and adults. To date, there are no published data regarding the pattern of 2D:4D in KS males. Here we consider 2D:4D in KS individuals (n = 51), their relatives (16 fathers and 15 mothers) and an unaffected control sample of 153 men and 153 women. Adult KS individuals were taller than their fathers and had shorter fingers than fathers and male controls. Compared with fathers, male controls and mothers, KS males had shorter fingers relative to height. With regard to 2D:4D, KS individuals had higher 2D:4D than fathers (right and left hands), male controls (right and left hands) and mothers (left hands). Among KS males older than 13 years there were 34 individuals currently prescribed testosterone and nine not prescribed. In comparison to the former, the latter individuals had higher right 2D:4D and higher right-left 2D:4D. We conclude that KS males have mean 2D:4D values similar to those found in female population norms. In addition, testosterone supplementation in KS males may be most common for individuals with low right 2D:4D. PMID:23258636

Manning, J T; Kilduff, L P; Trivers, R

2012-10-09

169

Functional Characterization of a First Avian Cytochrome P450 of the CYP2D Subfamily (CYP2D49)  

PubMed Central

The CYP2D family members are instrumental in the metabolism of 20–25% of commonly prescribed drugs. Although many CYP2D isoforms have been well characterized in other animal models, research concerning the chicken CYP2Ds is limited. In this study, a cDNA encoding a novel CYP2D enzyme (CYP2D49) was cloned from the chicken liver for the first time. The CYP2D49 cDNA contained an open reading frame of 502 amino acids that shared 52%–57% identities with other CYP2Ds. The gene structure and neighboring genes of CYP2D49 are conserved and similar to those of human CYP2D6. Additionally, similar to human CYP2D6, CYP2D49 is un-inducible in the liver and expressed predominantly in the liver, kidney and small intestine, with detectable levels in several other tissues. Metabolic assays of the CYP2D49 protein heterologously expressed in E. coli and Hela cells indicated that CYP2D49 metabolized the human CYP2D6 substrate, bufuralol, but not debrisoquine. Moreover, quinidine, a potent inhibitor of human CYP2D6, only inhibited the bufuralol 1?-hydroxylation activity of CYP2D49 to a negligible degree. All these results indicated that CYP2D49 had functional characteristics similar to those of human CYP2D6 but measurably differed in the debrisoquine 4?-hydroxylation and quinidine inhibitory profile. Further structure-function investigations that employed site-directed mutagenesis and circular dichroism spectroscopy identified the importance of Val-126, Glu-222, Asp-306, Phe-486 and Phe-488 in keeping the enzymatic activity of CYP2D49 toward bufuralol as well as the importance of Asp-306, Phe-486 and Phe-488 in maintaining the conformation of CYP2D49 protein. The current study is only the first step in characterizing the metabolic mechanism of CYP2D49; further studies are still required.

Yang, Qi; Chen, Qingmei; Deng, Yiqun

2012-01-01

170

Communication: Determining the lowest-energy isomer of Au8: 2D, or not 2D.  

PubMed

A parallel numerical derivative code, combined with parallel implementation of the coupled-cluster method with singles, doubles, and non-iterative triples (CCSD(T)), is used to optimize the geometries of the low-energy structures of the Au8 particle. The effects of geometry relaxation at the CCSD(T) level and the combined effects of the basis set and core-valence correlations are examined and the results are compared with the corresponding second-order Mo?ller-Plesset perturbation theory calculations. The highest-level computations, in which the single-point CCSD(T) calculations employing the correlation-consistent basis set of the cc-pVTZ quality and the associated relativistic effective core potential (ECP), both optimized for gold, and correlating the 5d(10)6s(1) valence and 5s(2)5p(6) semi-core electrons, are combined with the geometrical information obtained with the corresponding CCSD(T)/cc-pVDZ/ECP approach, favor the planar configuration, with the next three non-planar structures separated by 4-6 kcal/mol. In agreement with the earlier work, smaller-basis set CCSD(T) computations provide unreliable results for the relative energetics, even when the geometries are optimized at the CCSD(T) level. PMID:24028093

Hansen, Jared A; Piecuch, Piotr; Levine, Benjamin G

2013-09-01

171

Integrating Transformation Geometry into Traditional High School Geometry.  

ERIC Educational Resources Information Center

Describes a geometry course that integrates transformation geometry into traditional high school geometry. Discussion of the scope and sequence of the course includes the topics of proof, congruence, translations, rotations, reflections, dilations, quadrilaterals, parallel lines, and similarity. (MDH)

Okolica, Steve; Macrina, Georgette

1992-01-01

172

Additional Invariants and Statistical Equilibria for the 2D Euler Equations on a Spherical Domain  

NASA Astrophysics Data System (ADS)

The role of the domain geometry for the statistical mechanics of 2D Euler flows is investigated. It is shown that for a spherical domain, there exists invariant subspaces in phase space which yield additional angular momentum, energy and enstrophy invariants. The microcanonical measure taking into account these invariants is built and a mean-field, Robert-Sommeria-Miller theory is developed in the simple case of the energy-enstrophy measure. The variational problem is solved analytically and a partial energy condensation is obtained. The thermodynamic properties of the system are also discussed.

Herbert, Corentin

2013-09-01

173

Observation of a 2D Bose Gas: From Thermal to Quasicondensate to Superfluid  

SciTech Connect

We present experimental results on a Bose gas in a quasi-2D geometry near the Berezinskii, Kosterlitz, and Thouless (BKT) transition temperature. By measuring the density profile after time of flight and the coherence length, we identify different states of the gas. We observe that the gas develops a bimodal distribution without long range order. In this regime, the gas presents a longer coherence length than the thermal cloud; it is quasicondensed but is not superfluid. Experimental evidence indicates that we also observe the superfluid transition (BKT transition). For a sufficiently long time of flight, we observe a trimodal distribution when the gas has developed a superfluid component.

Clade, P.; Ryu, C.; Ramanathan, A.; Helmerson, K.; Phillips, W. D. [Atomic Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8424 (United States) and Joint Quantum Institute, NIST and University of Maryland, College Park, Maryland 20742 (United States)

2009-05-01

174

Proof in Transformation Geometry  

ERIC Educational Resources Information Center

|The first of three articles showing how inductively-obtained results in transformation geometry may be organized into a deductive system. This article discusses two approaches to enlargement (dilatation), one using coordinates and the other using synthetic methods. (MM)|

Bell, A. W.

1971-01-01

175

Bupropion plasma levels and CYP2D6 phenotype.  

PubMed

All available antidepressants with the exception of fluvoxamine and nefazodone either are metabolized by cytochrome P450 2D6 (CYP2D6) and/or inhibit this isozyme. To date, nothing in this regard has been published concerning bupropion. We report that plasma level/dose ratios for bupropion, and its metabolites erythrohydrobupropion and threohydrobupropion, were not associated with debrisoquine metabolic status in 12 patients, three of whom were poor 2D6 metabolizers. The plasma level/dose ratios for the metabolite hydroxybupropion were, however, significantly higher in poor 2D6 metabolizers. In three patients, who received a second phenotyping test during treatment with bupropion, debrisoquine metabolic ratios were not increased. It is thus inferred that bupropion is neither metabolized by nor inhibits CYP2D6. The potential accumulation of hydroxybupropion after CYP2D6 inhibition may, however, contribute to toxicity and impair bupropion's therapeutic effectiveness. PMID:8885123

Pollock, B G; Sweet, R A; Kirshner, M; Reynolds, C F

1996-10-01

176

Optical correlation and convolution of real 2D inputs and real 2D filters  

NASA Astrophysics Data System (ADS)

Frequently in character recognition, there is a need to correlate or convolve purely real 2D inputs and real 2D filters. We propose two optical correlators. The first, basic real-input-real-filter optical correlator, adds x and y mirror images adjacent to the image to generate real and even images. This avoids the need for an offset reference to capture phase. Therefore, we have greater diffraction efficiency and a reduction in filter LCD pixel size. The second, Hilbert transform basic real-input-real-filter optical correlator, uses a Hilbert transform by masking in the filter plane to reduce the number elements in the filter LCD to that of the number of pixels in a filter image. An optical system can generate the mirror images in real time so that both the input LCD and the filter LCD can have only the same number of elements as their respective number of image pixels. We show how a spatial filter can be used to remove the intensity offset produced in the Hilbert transform and restore shift invariance if required. Finally, if desired, some rotation invariance can be achieved by overlapping the mirror images with the basic correlator. Advantages and disadvantages of the proposed correlators are discussed.

McAulay, Alastair D.

1999-10-01

177

Science U: Geometry Center  

NSDL National Science Digital Library

Science UTM offers online articles and activities for people who like science. Science U and the web-design and development company that owns and operates the website, Geometry Technologies, were formed as a result of the closure of The Geometry Center at the University of Minnesota. One of the conditions of that grant, which funded The Geometry Center and ended in 1998, was that the Center would find a way to keep their materials available to the public. In anticipation of the day when the Geometry Center goes offline, they are slowly migrating materials to this website. The Geometry Center section at Science U offers lessons on solids using interactive models, geometry tiling activities, an interactive fractal generator, and many other puzzles, articles and activities. Visitors can search their resources using an online query form or by browsing the topic index, subject listing or content listing. The content listing gives you an idea of the different types of resources available, such as articles, facts and figures, classroom materials, online simulations, hands-on-projects, or software. The Science U also offers other sections on astronomy, graphic arts, and a library with various online and print resources on science.

2007-12-12

178

A 2D simple attenuation model for EM waves in human tissues: Comparison with a FDTD 3D simulator for UWB medical radar  

Microsoft Academic Search

This paper describes a simple 2D model for the propagation of electro-magnetic (EM) pulses in human tissues. To assess the reliability of using this model for fast attenuation evaluation of UWB radar pulses in the body, the model is compared with a well known 3D FDTD numeric simulator using a simple multilayer geometry. Results from the 2D model were found

G. Varotto; E. M. Staderini

2008-01-01

179

Low-complexity 2D to 3D video conversion  

Microsoft Academic Search

3D film and 3D TV are becoming reality. More facilities and devices are now 3D capable. Compared to capture 3D video content directly, 2D to 3D video conversion is a low-cost, backward compatible alternate. There also exists a tremendous amount of monoscopic 2D video content that are of high interest to be displayed on 3D devices with noticeable immersiveness. 2D

Ying Chen; Rong Zhang; Marta Karczewicz

2011-01-01

180

CFD Investigation of 2D and 3D Dynamic Stall  

Microsoft Academic Search

1 ABSTRACT Numerical simulation has been performed for 2-D and 3-D dynamic stall cases. Square wings of NACA 0012 and NACA 0015 sections were employed and results have been compared against experimental data by Wernert et. al. [14] for the 2-D and Schreck and Helin [12] for the 3-D cases. The well-known flow configuration of the 2-D dynamic stall case

A. Spentzos; G. Barakos; K. Badcock; B. Richards; P. Wernert; S. Schreck; M. Raffel

181

Performance of mobile camera on colour 2D barcode  

Microsoft Academic Search

In recent years, colour 2D barcodes have emerged to increase the data capacity of the 2D barcode. Similarly, camera-equipped mobile phones have became more popular and their camera could act as an input device for a barcode decoder. In this paper, three Windows Mobile (WM) operated mobile phones are used to test their camera performance in reading the colour 2D

Siong Khai Ong; Douglas Chai; Keng T. Tan

2009-01-01

182

The effect of psychotropic drugs on cytochrome P450 2D (CYP2D) in rat brain.  

PubMed

The aim of the study was to investigate the influence of selected antidepressants and neuroleptics on the protein level and activity of cytochrome P450 2D (CYP2D) in rat brain. The obtained results showed that imipramine, fluoxetine, nefazodone, thioridazine and perazine, added to brain microsomes of control rats, inhibited CYP2D activity to a lower extent (K(i)=255-485?M) than when added to liver microsomes (K(i)=1-45?M), which may result from their stronger affinity for liver CYP2D2 (K(i)=2.7 and 1.25?M for imipramine and fluoxetine, respectively) than for brain CYP2D4 (K(i)=25 and 10?M for imipramine and fluoxetine, respectively), as well as from their high non-specific binding in brain microsomes. Two-week treatment with fluoxetine evoked decreases in the level and activity of CYP2D in the striatum and the nucleus accumbens. In contrast, fluoxetine increased CYP2D expression in the cerebellum, while nefazodone considerably enhanced the activity (but not the protein level) of CYP2D in the truncus cerebri. Imipramine and mirtazapine (active in the liver) did not affect brain CYP2D. Chronic thioridazine decreased CYP2D activity in the substantia nigra and nucleus accumbens, but significantly increased that activity in the striatum and cerebellum. Clozapine significantly enhanced CYP2D activity in the truncus cerebri. In conclusion, psychotropics influence CYP2D in the brain, but their effect is different than in the liver and depends on the cerebral structure. The observed psychotropics-brain CYP2D interactions may be important for the metabolism of neurosteroids and monoaminergic neurotransmitters, and for the local biotransformation of drugs. PMID:21115002

Haduch, Anna; Bromek, Ewa; Daniel, W?adys?awa A

2010-11-27

183

Complexities of CYP2D6 gene analysis and interpretation.  

PubMed

Abstract Cytochrome P450 2D6 (CYP2D6) plays an important role in the metabolism and bioactivation of about 25% of clinically used drugs including many antidepressants, antipsychotics and opioids. CYP2D6 activity is highly variably ranging from no activity in so-called poor metabolizers to ultrarapid metabolism at the other end of the extreme of the activity distribution. A large portion of this variability can be explained by the highly polymorphic nature of the CYP2D6 gene locus for which > 100 variants and subvariants identified to date. Allele frequencies vary markedly between ethnic groups; some have exclusively or predominantly only been observed in certain populations. Pharmacogenetic testing holds the promise of individualizing drug therapy by identifying patients with CYP2D6 diplotypes that puts them at an increased risk of experiencing dose-related adverse events or therapeutic failure. Inferring a patient's CYP2D6 metabolic capacity, or phenotype, however, is a challenging task due to the complexity of the CYP2D6 gene locus. Allelic variation includes SNPs, small insertions and deletions, gene copy number variation and rearrangements with CYP2D7, a highly related non-functional gene. This review provides a summary of the intricacies of CYP2D6 variation and genotype analysis, knowledge that is invaluable for the translation of genotype into clinically useful information. PMID:24151800

Gaedigk, Andrea

2013-10-01

184

Neutrino masses, dominant neutrinoless double beta decay, and observable lepton flavor violation in left-right models and SO(10) grand unification with low mass W R , Z R bosons  

NASA Astrophysics Data System (ADS)

While the detection of W R-boson at the Large Hadron Collider is likely to resolve the mystery of parity violation in weak interaction, observation of neutrinoless double beta decay (0 ???) is expected to determine whether neutrinos are Majorana fermions. In this work we consider a class of LR models with TeV scale W R , Z R bosons but having parity restoration at high scales where they originate from well known Pati-Salam symmetry or SO(10) grand unified theory minimally extended to accommodate inverse seesaw frame work for neutrino masses. Most dominant new contribution to neutrinoless double beta decay is noted to occur via mediation involving lighter sterile neutrino exchanges. The next dominant contribution is found to be through mediation involving both light and heavy right-handed neutrino or sterile neutrino exchanges. The quark-lepton symmetric origin of the computed value of the Dirac neutrino mass matrix is also found to play a crucial role in determining these and other results on lepton flavor violating branching ratios for ? ? e + ?, ? ? ? + ?, and ? ? e + ? accessible to ongoing search experiments. The underlying non-unitarity matrix is found to manifest in substantial CP-violating effects even when the leptonic Dirac phase ?CP ? 0 ,? ,2?. Finally we explore a possible origin of the model in non-supersymmetric SO(10) grand unified theory where, in addition to low mass and Z R bosons accessible to Large Hadron Collider, the model is found to predict observable neutron-antineutron oscillation and lepto-quark gauge boson(mediated rare kaon decay with ? 10-9 - 10-11).

Awasthi, Ram Lal; Parida, M. K.; Patra, Sudhanwa

2013-08-01

185

AnisWave2D: User's Guide to the 2d Anisotropic Finite-DifferenceCode  

SciTech Connect

This document describes a parallel finite-difference code for modeling wave propagation in 2D, fully anisotropic materials. The code utilizes a mesh refinement scheme to improve computational efficiency. Mesh refinement allows the grid spacing to be tailored to the velocity model, so that fine grid spacing can be used in low velocity zones where the seismic wavelength is short, and coarse grid spacing can be used in zones with higher material velocities. Over-sampling of the seismic wavefield in high velocity zones is therefore avoided. The code has been implemented to run in parallel over multiple processors and allows large-scale models and models with large velocity contrasts to be simulated with ease.

Toomey, Aoife

2005-01-06

186

Students Discovering Spherical Geometry Using Dynamic Geometry Software  

ERIC Educational Resources Information Center

|Dynamic geometry software (DGS) such as Cabri and Geometers' Sketchpad has been regularly used worldwide for teaching and learning Euclidean geometry for a long time. The DGS with its inductive nature allows students to learn Euclidean geometry via explorations. However, with respect to non-Euclidean geometries, do we need to introduce them to…

Guven, Bulent; Karatas, Ilhan

2009-01-01

187

Students discovering spherical geometry using dynamic geometry software  

Microsoft Academic Search

Dynamic geometry software (DGS) such as Cabri and Geometers’ Sketchpad has been regularly used worldwide for teaching and learning Euclidean geometry for a long time. The DGS with its inductive nature allows students to learn Euclidean geometry via explorations. However, with respect to non-Euclidean geometries, do we need to introduce them to students in a deductive manner? Do students have

Bulent Guven; Ilhan Karatas

2009-01-01

188

Sensitivity analysis of imaging geometries for prostate diffuse optical tomography  

NASA Astrophysics Data System (ADS)

Endoscopic and interstitial diffuse optical tomography have been studied in clinical investigations for imaging prostate tissues, yet, there is no comprehensive comparison of how these two imaging geometries affect the quality of the reconstruction images. In this study, the effect of imaging geometry is investigated by comparing the cross-section of the Jacobian sensitivity matrix and reconstructed images for three-dimensional mathematical phantoms. Next, the effect of source-detector configurations and number of measurements in both geometries is evaluated using singular value analysis. The amount of information contained for each source-detector configuration and different number of measurements are compared. Further, the effect of different measurements strategies for 3D endoscopic and interstitial tomography is examined. The pros and cons of using the in-plane measurements and off-plane measurements are discussed. Results showed that the reconstruction in the interstitial geometry outperforms the endoscopic geometry when deeper anomalies are present. Eight sources 8 detectors and 6 sources 12 detectors are sufficient for 2D reconstruction with endoscopic and interstitial geometry respectively. For a 3D problem, the quantitative accuracy in the interstitial geometry is significantly improved using off-plane measurements but only slightly in the endoscopic geometry.

Zhou, Xiaodong; Zhu, Timothy C.

2008-03-01

189

Integrating Mobile Multimedia into Textbooks: 2D Barcodes  

ERIC Educational Resources Information Center

The major goal of this study was to empirically compare text-plus-mobile phone learning using an integrated 2D barcode tag in a printed text with three other conditions described in multimedia learning theory. The method examined in the study involved modifications of the instructional material such that: a 2D barcode was used near the text, the…

Uluyol, Celebi; Agca, R. Kagan

2012-01-01

190

2D full field vibration analysis with multiplexed digital holograms  

Microsoft Academic Search

Opportunities for full field 2D amplitude and phase vibration analysis are presented. It is demonstrated that it is possible to simultaneously encode-decode 2D the amplitude and phase of harmonic mechanical vibrations. The process allows the determination of in plane and out of plane vibration components when the object is under a pure sinusoidal excitation. The principle is based on spatial

Pascal Picart; Julien Leval; Jean Claude Pascal; Jean Pierre Boileau; Michel Grill; Jean Marc Breteau; Benjamin Gautier; Stéphane Gillet

2005-01-01

191

2D-SEEP Computer Code User's Manual.  

National Technical Information Service (NTIS)

This report describes the 2D-SEEP computer code and presents the direction to use the code effectively. 2D-SEEP code can handle coupled groundwater flow and heat transport, and saturated-unsaturated groundwater flow in a permeable geologic media for the s...

H. Kimura

1988-01-01

192

Matrix Models of 2D Gravity and Isomonodromic Deformation  

Microsoft Academic Search

We study the double scaling limit of orthogonal polynomials arising in matrix models of 2D gravity. These ``Baker-Akhiezer functions'' satisfy linear differential equations whose compatibility conditions are the string and KP flow equations. Moreover, these functions may be interpreted as two-point functions for a 2D field theory on the eigenvalue plane.

Gregory Moore

1990-01-01

193

An Implicit Surface based 2-D \\/ 3-D Medial Extractor  

Microsoft Academic Search

ABSTRACT Medial axis of an ,object is an ,important property ,that is used ,in a ,variety of applications. Although many algorithms are available in 2-D, only a few algorithms are available for 3-D problems. Hence, a medial extractor applicable for both 2-D and 3-D problems, customized for future mesh generation applications, is desired. This thesis presents an implicit surface based

Ragunath Sankaranarayanan

2003-01-01

194

Thermal conduction in a 2-D FCT plasma hydrodynamic code  

Microsoft Academic Search

This paper presents an algorithm for inclusion of thermal conduction in a 2-D hydrodynamic code for compressible inviscid plasmas. The code is flexible for a wide series of applications in astrophysics, solves the hydrodynamic equations in conservative form in the most used coordinate systems and is based on an explicit fully 2-D flux corrected transport technique (FCT). The algorithm separates

F. Reale

1995-01-01

195

Integrating Mobile Multimedia into Textbooks: 2D Barcodes  

ERIC Educational Resources Information Center

|The major goal of this study was to empirically compare text-plus-mobile phone learning using an integrated 2D barcode tag in a printed text with three other conditions described in multimedia learning theory. The method examined in the study involved modifications of the instructional material such that: a 2D barcode was used near the text, the…

Uluyol, Celebi; Agca, R. Kagan

2012-01-01

196

Novel 2-D photonic bandgap structure for microstrip lines  

Microsoft Academic Search

A new two-dimensional (2-D) photonic bandgap (PBG) structure for microstrip lines is proposed, in which a periodic 2-D pattern consisting of circles is etched in the ground plane of microstrip line. No drilling through the substrate is required. Three PBG circuits were fabricated with different circle radii to determine the optimum dimensions, as well as a PBG circuit with the

Vesna Radisic; Yongxi Qian; Roberto Coccioli; Tatsuo Itoh

1998-01-01

197

Alhambra: A System for Producing 2D Animation  

Microsoft Academic Search

There is a great interest in producing computer animation that looks like 2D classic animation. The flat shading, silhouettes and inside contour lines are all visual characteristics that, joined to flexible expressiveness, constitute the basic elements of 2D animation. We have developed methods for obtaining the silhouettes and interior curves from polygonal models. Virtual lights is a new method for

Domingo Martín; Juan Carlos Torres

1999-01-01

198

A new method for quantification of liquid saturation in 2D translucent porous media systems using light transmission  

Microsoft Academic Search

Five physically based models for predicting liquid saturation from light transmission in 2D laboratory systems containing translucent porous media were developed and tested (Models A–E). The models were based upon various simplifying assumptions concerning pore geometry, wettability, and drainage. Models A–D assumed uniform-sized pores, and liquid saturation was an explicit function of light transmission. Model E considered a distribution of

Michael R. Niemet; John S. Selker

2001-01-01

199

2D cross-borehole resistivity tomographies below foundations as a tool to design proper remedial actions in covered karst  

Microsoft Academic Search

To assess the subsurface conditions beneath a 4-floor public building, where sinkhole collapses had already occurred, twenty-three 2D cross-borehole resistivity tomographies were conducted beneath the building foundations in January and February 2004. The aim of these geophysical investigations was to build a model of the complex subsurface geometry in order to estimate and minimize costs of remediation works.In cross-borehole resistivity

J. Deceuster; J. Delgranche; O. Kaufmann

2006-01-01

200

Regulation of ligands for the NKG2D activating receptor.  

PubMed

NKG2D is an activating receptor expressed by all NK cells and subsets of T cells. It serves as a major recognition receptor for detection and elimination of transformed and infected cells and participates in the genesis of several inflammatory diseases. The ligands for NKG2D are self-proteins that are induced by pathways that are active in certain pathophysiological states. NKG2D ligands are regulated transcriptionally, at the level of mRNA and protein stability, and by cleavage from the cell surface. In some cases, ligand induction can be attributed to pathways that are activated specifically in cancer cells or infected cells. We review the numerous pathways that have been implicated in the regulation of NKG2D ligands, discuss the pathologic states in which those pathways are likely to act, and attempt to synthesize the findings into general schemes of NKG2D ligand regulation in NK cell responses to cancer and infection. PMID:23298206

Raulet, David H; Gasser, Stephan; Gowen, Benjamin G; Deng, Weiwen; Jung, Heiyoun

2013-01-03

201

Quantum Geometry and Interferometry  

NASA Astrophysics Data System (ADS)

All existing experimental results are currently interpreted using classical geometry. However, there are theoretical reasons to suspect that at a deeper level, geometry emerges as an approximate macroscopic behavior of a quantum system at the Planck scale. If directions in emergent quantum geometry do not commute, new quantum-geometrical degrees of freedom can produce detectable macroscopic deviations from classicality: spatially coherent, transverse position indeterminacy between any pair of world lines, with a displacement amplitude much larger than the Planck length. Positions of separate bodies are entangled with each other, and undergo quantum-geometrical fluctuations that are not describable as metric fluctuations or gravitational waves. These fluctuations can either be cleanly identified or ruled out using interferometers. A Planck-precision test of the classical coherence of space-time on a laboratory scale is now underway at Fermilab.

Hogan, C.

2013-01-01

202

Geometry and Cloaking Devices  

NASA Astrophysics Data System (ADS)

Recently, the application of geometry and conformal mappings to artificial materials (metamaterials) has attracted the attention in various research communities. These materials, characterized by a unique man-made structure, have unusual optical properties, which materials found in nature do not exhibit. By applying the geometry and conformal mappings theory to metamaterial science, it may be possible to realize so-called ``Harry Potter cloaking device''. Although such a device is still in the science fiction realm, several works have shown that by using such metamaterials it may be possible to control the direction of the electromagnetic field at will. We could then make an object hidden inside of a cloaking device. Here, we will explain how to design invisibility device using differential geometry and conformal mappings.

Ochiai, T.; Nacher, J. C.

2011-09-01

203

Universality of geometry  

NASA Astrophysics Data System (ADS)

In models of emergent gravity the metric arises as the expectation value of some collective field. Usually, many different collective fields with appropriate tensor properties are candidates for a metric. Which collective field describes the "physical geometry"? We resolve this "metric ambiguity" by an investigation of the most general form of the quantum effective action for several metrics. In the long-distance limit the physical metric is universal and accounts for a massless graviton. Other degrees of freedom contained in the various metric candidates describe very massive scalars and symmetric second rank tensors. They only play a role at microscopic distances, typically around the Planck length. The universality of geometry at long distances extends to the vierbein and the connection. On the other hand, for distances and time intervals of Planck size geometry looses its universal meaning. Time is born with the big bang.

Wetterich, C.

2012-05-01

204

Aspects of global Riemannian geometry  

Microsoft Academic Search

In this article we survey some of the developments in Riemann- ian geometry. We place special emphasis on explaining the relationship be- tween curvature and topology for Riemannian manifolds with lower curvature bounds. We shall in this survey explain the development of the branch of Riemannian geometry called global Riemannian geometry. The main goal of this particular type of geometry

Peter Petersen

1999-01-01

205

High-frequency susceptibility of a superlattice with 2D inhomogeneities  

SciTech Connect

We investigate the high-frequency susceptibility (Green function) of an initially sinusoidal 1D superlattice with 2D phase inhomogeneities that model the deformations of the interfaces between the superlattice layers. For waves propagating along the superlattice axis (the geometry of a photon or magnon crystal), we have found a peculiar behavior of the imaginary part of the Green function that consists in a significant difference between the peaks corresponding to the edges of the band gap in the wave spectrum. The peak corresponding to the lower-frequency band edge remains essentially unchanged as the root-mean-square fluctuation of the 2D inhomogeneities {gamma}{sub 2} increases, while the peak corresponding to the higher-frequency band edge broaden and decreases sharply in height until its complete disappearance with increasing {gamma}{sub 2}. This behavior of the peaks corresponds to a band gap closure mechanism that differs from the traditional one characteristic of 1D and 3D inhomogeneities. These effects can be explained by a peculiarity of the energy conservation laws for the incident and scattered waves for 2D inhomogeneities in a 1D superlattice.

Ignatchenko, V. A.; Mankov, Yu. I. [Russian Academy of Sciences, Siberian Branch, L.V. Kirenskii Institute of Physics (Russian Federation)], E-mail: mankov@iph.krasn.ru; Tsikalov, D. S. [Siberian Federal University (Russian Federation)

2008-10-15

206

Semimetal–superfluid quantum phase transitions in 2D and 3D lattices with Dirac points  

NASA Astrophysics Data System (ADS)

We study the superfluid properties of attractively interacting fermions hopping in a family of 2D and 3D lattices in the presence of synthetic gauge fields having ?-flux per plaquette. The reason for such a choice is that the ?-flux cubic lattice displays Dirac points and that decreasing the hopping coefficient in a spatial direction (say, tz), these Dirac points are unaltered: it is then possible to study the 3D–2D interpolation towards the ?-flux square lattice. We also consider the lattice configuration providing the continuous interpolation between the 2D ?-flux square lattice and the honeycomb geometry. We investigate by a mean-field analysis the effects of interaction and dimensionality on the superfluid gap, chemical potential and critical temperature, showing that these quantities continuously vary along the patterns of interpolation. In the two-dimensional cases at zero temperature and half-filling, there is a quantum phase transition occurring at a critical (negative) interaction Uc presenting a linear critical exponent for the gap as a function of |U ? Uc|. We show that in three dimensions, this quantum phase transition is again retrieved, pointing out that the critical exponent for the gap changes from 1 to 1/2 for each finite value of tz.

Mazzucchi, G.; Lepori, L.; Trombettoni, A.

2013-07-01

207

Assessment of an ASTER-generated DEM for 2D hydrodynamic flood modeling  

NASA Astrophysics Data System (ADS)

Flood modeling often provides inputs to flood hazard management. In the present work we studied the flooding characteristics in the data scarce region of the Lake Tana basin at the source of the Blue Nile River. The study required to integrate remote sensing, GIS with a two-dimensional (2D) module of the SOBEK flood model. The resolution of the topographic data in many areas, such as the Lake Tana region, is commonly too poor to support detailed 2D hydrodynamic modeling. To overcome such limitations, we used a Digital Elevation Model (DEM) which was generated from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image. A GIS procedure is developed to reconstruct the river terrain and channel bathymetry. The results revealed that a representation of the river terrain largely affects the simulated flood characteristics. Simulations indicate that effects of Lake Tana water levels propagate up to 13 km along the Ribb River. We conclude that a 15 m resolution ASTER DEM can serve as an input to detailed 2D hydrodynamic modeling in data scarce regions. However, for this purpose it is necessary to accurately reconstruct the river terrain geometry and flood plain topography based on ground observations by means of a river terrain model.

Tarekegn, Tesfaye Haimanot; Haile, Alemseged Tamiru; Rientjes, Tom; Reggiani, P.; Alkema, Dinand

208

NKG2D CAR T-cell therapy inhibits the growth of NKG2D ligand heterogeneous tumors.  

PubMed

Tumor heterogeneity presents a substantial barrier to increasing clinical responses mediated by targeted therapies. Broadening the immune response elicited by treatments that target a single antigen is necessary for the elimination of tumor variants that fail to express the targeted antigen. In this study, it is shown that adoptive transfer of T cells bearing a chimeric antigen receptor (CAR) inhibited the growth of target-expressing and -deficient tumor cells within ovarian and lymphoma tumors. Mice bearing the ID8 ovarian or RMA lymphoma tumors were treated with T cells transduced with a NKG2D-based CAR (chNKG2D). NKG2D CAR T-cell therapy protected mice from heterogeneous RMA tumors. Moreover, adoptive transfer of chNKG2D T cells mediated tumor protection against highly heterogeneous ovarian tumors in which 50, 20 or only 7% of tumor cells expressed significant amounts of NKG2D ligands. CAR T cells did not mediate an in vivo response against tumor cells that did not express sufficient amounts of NKG2D ligands, and the number of ligand-expressing tumor cells correlated with therapeutic efficacy. In addition, tumor-free surviving mice were protected against a tumor re-challenge with NKG2D ligand-negative ovarian tumor cells. These data indicate that NKG2D CAR T-cell treatment can be an effective therapy against heterogeneous tumors and induce tumor-specific immunity against ligand-deficient tumor cells. PMID:23628805

Spear, Paul; Barber, Amorette; Rynda-Apple, Agnieszka; Sentman, Charles L

2013-04-30

209

Parallel Computational Geometry  

Microsoft Academic Search

We present efficient parallel algorithms for several basic problems in computational geometry: convex hulls, Voronoi diagrams,\\u000a detecting line segment intersections, triangulating simple polygons, minimizing a circumscribing triangle, and recursive data-structures\\u000a for three-dimensional queries.

Alok Aggarwal; Bernard Chazelle; Leonidas J. Guibas; Colm Ó'dúnlaing; Chee-keng Yap

1988-01-01

210

Geometry of Thermodynamic States  

Microsoft Academic Search

the canonical distribution of classical statistical mechanics. In this scheme thermodynamic states, or equivalently, statistical mechanical states, can be characterised concisely in terms of the geometry of a submanifold M of the unit sphere S in a real Hilbert space H. The measurement of a thermodynamic variable then corresponds to the reduction of a state vector in H to an

Dorje C. Brodyand

211

Geoff Giles and Geometry  

ERIC Educational Resources Information Center

Geoff Giles died suddenly in 2005. He was a highly original thinker in the field of geometry teaching. As early as 1964, when teaching at Strathallen School in Perth, he was writing in "MT27" about constructing tessellations by modifying the sides of triangles and (irregular) quadrilaterals to produce what he called "trisides" and "quadrisides".…

Fielker, David

2007-01-01

212

Geometry Scavenger Hunt  

NSDL National Science Digital Library

This activity allows learners to practice observation skills and to realize examples of geometric shapes are everywhere. This geometry scavenger hunt (PDF) contains a set of directions and a recording sheet to complete. Included also is a list of materials and extension ideas.

2010-01-01

213

The Geometry Tutor  

Microsoft Academic Search

The tutor for doing proofs in high school geometry consists of a cot of ideal and buggy rules (IRR), a tutor, and an interface. The IBR is responsible for ehiuertly computing matcher, to all the correct and incorrect rules The interface is responsible for interacting with the student and graphically representing the proof. The tutor is responsible for directing the

John R. Anderson; C. Franklin Boyle; Gregg Yost

1985-01-01

214

Geometry in 3-D  

NSDL National Science Digital Library

This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. The online resources featured in Geometry in 3-D actively engage students in exploring a variety of geometric shapes, at times through lessons that involve building models or creating paper nets that fold into three-dimensional shapes; at other times, through technology that allows students to rotate and zoom in on figures, noting their attributes and complexity. Other lessons offer problems on surface area and volume, a part of every middle school curriculum. The problems, each with a different twist on the subject, challenge students to reconsider their understanding of how to measure solids. Activities for developing spatial sense, another primary objective in teaching geometry, are also featured. Finally, there are online galleries of geometric solids, included for the rare opportunity they offer to show your students the beauty in mathematics. In Background Information, you will find workshop sessions developed for teachers and other materials that may interest you as a professional. Each resource deals specifically with three-dimensional geometry topics that align with the geometry and measurement standards recommended by NCTM.

Herrera, Terese

2006-09-01

215

Foundations of basic geometry  

Microsoft Academic Search

The basic notions of length, area and volume were not alien to the prehistoric civilizations. The pyramids, palaces and great\\u000a baths built more than 4000 years ago provide ample evidence. We begin our investigation of geometry with a discussion of areas\\u000a of simple geometric objects.

Jasbir S. Chahal

2006-01-01

216

Gravity is Geometry.  

ERIC Educational Resources Information Center

|Clarifies two concepts of gravity--those of a fictitious force and those of how space and time may have geometry. Reviews the position of Newton's theory of gravity in the context of special relativity and considers why gravity (as distinct from electromagnetics) lends itself to Einstein's revolutionary interpretation. (JN)|

MacKeown, P. K.

1984-01-01

217

Noncommutative geometry and reality  

Microsoft Academic Search

We introduce the notion of realstructure in our spectral geometry. This notion is motivated by Atiyah’s KR-theory and by Tomita’s involution J. It allows us to remove two unpleasant features of the ‘‘Connes–Lott’’ description of the standard model, namely, the use of bivector potentials and the asymmetry in the Poincare´ duality and in the unimodularity condition.

Alain Connes

1995-01-01

218

Geometry in Engineering Education.  

ERIC Educational Resources Information Center

|Discusses the importance of mathematical geometric education for engineers. Describes geometry as the basic platform to get involved with the creation of models in the forms of images which can offer an unprecedented basis for logical reasoning supported by practical applications. (Author/YDS)|

Velichova, Daniela

2002-01-01

219

Geometry-controlled kinetics  

Microsoft Academic Search

It has long been appreciated that the transport properties of molecules can control reaction kinetics. This effect can be characterized by the time it takes a diffusing molecule to reach a target-the first-passage time (FPT). Determining the FPT distribution in realistic confined geometries has until now, however, seemed intractable. Here, we calculate this FPT distribution analytically and show that transport

O. Bénichou; C. Chevalier; J. Klafter; B. Meyer; R. Voituriez

2010-01-01

220

The Geometry of Terrorism  

Microsoft Academic Search

Terrorism in its purest form is self-help by organized civilians who covertly inflict mass violence on other civilians. Pure sociology explains terrorism with its social geometry—its multidimensional location and direction in social space. Here Ibuild on the work of Senechal de la Roche (1996) and propose the following geometrical model: Pure terrorism arises intercollectively and upwardly across long distances in

Donald Black

2004-01-01

221

Algebraic Geometry and Physics  

Microsoft Academic Search

This article is an interdisciplinary review and an on-going progress report over the last few years made by myself and collaborators in certain fundamental subjects on two major theoretic branches in mathematics and theoretical physics: algebraic geometry and quantum physics. I shall take a practical approach, concentrating more on explicit examples rather than formal developments. Topics covered are divided in

Shi-shyr Roan

2000-01-01

222

Remarks on Euclidean Geometry  

Microsoft Academic Search

\\u000a You have studied geometry in high school, a version of what was assembled from knowledge of the ancient Greeks (around 300\\u000a BCE) by the Greek-speaking textbook writer Euclid, who lived in Alexandria, Egypt.

Matthias Beck; Ross Geoghegan

223

Geometry of Dupin Cyclides.  

National Technical Information Service (NTIS)

In the 19th century, the French geometer Charles Pierre Dupin discovered a nonspherical surface with circular lines of curvature. He called it cyclide in his book, Applications de Geometrie published in 1822. Recently, cyclides have been revived for use a...

V. Chandru D. Dutta C. M. Hoffmann

1989-01-01

224

2D vs. 3D mammography observer study  

NASA Astrophysics Data System (ADS)

Breast cancer is the most common type of non-skin cancer in women. 2D mammography is a screening tool to aid in the early detection of breast cancer, but has diagnostic limitations of overlapping tissues, especially in dense breasts. 3D mammography has the potential to improve detection outcomes by increasing specificity, and a new 3D screening tool with a 3D display for mammography aims to improve performance and efficiency as compared to 2D mammography. An observer study using a mammography phantom was performed to compare traditional 2D mammography with this ne 3D mammography technique. In comparing 3D and 2D mammography there was no difference in calcification detection, and mass detection was better in 2D as compared to 3D. There was a significant decrease in reading time for masses, calcifications, and normals in 3D compared to 2D, however, as well as more favorable confidence levels in reading normal cases. Given the limitations of the mammography phantom used, however, a clearer picture in comparing 3D and 2D mammography may be better acquired with the incorporation of human studies in the future.

Fernandez, James Reza F.; Hovanessian-Larsen, Linda; Liu, Brent

2011-03-01

225

Bose-einstein condensation in quasi-2D trapped gases  

PubMed

We discuss Bose-Einstein condensation (BEC) in quasi-2D trapped gases and find that well below the transition temperature T(c) the equilibrium state is a true condensate, whereas at intermediate temperatures T2D gas is sensitive to the frequency omega(0) of the (tight) confinement in the "frozen" direction, and one can switch the sign of the interaction by changing omega(0). Variation of omega(0) can also reduce the rates of inelastic processes. This offers promising prospects for tunable BEC in trapped quasi-2D gases. PMID:11017267

Petrov; Holzmann; Shlyapnikov

2000-03-20

226

2D electron cyclotron emission imaging at ASDEX Upgrade (invited)  

SciTech Connect

The newly installed electron cyclotron emission imaging diagnostic on ASDEX Upgrade provides measurements of the 2D electron temperature dynamics with high spatial and temporal resolution. An overview of the technical and experimental properties of the system is presented. These properties are illustrated by the measurements of the edge localized mode and the reversed shear Alfven eigenmode, showing both the advantage of having a two-dimensional (2D) measurement, as well as some of the limitations of electron cyclotron emission measurements. Furthermore, the application of singular value decomposition as a powerful tool for analyzing and filtering 2D data is presented.

Classen, I. G. J. [Max Planck Institut fuer Plasmaphysik, 85748 Garching (Germany); FOM-Institute for Plasma Physics, Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Boom, J. E.; Vries, P. C. de [FOM-Institute for Plasma Physics, Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Suttrop, W.; Schmid, E.; Garcia-Munoz, M.; Schneider, P. A. [Max Planck Institut fuer Plasmaphysik, 85748 Garching (Germany); Tobias, B.; Domier, C. W.; Luhmann, N. C. Jr. [University of California at Davis, Davis, California 95616 (United States); Donne, A. J. H. [FOM-Institute for Plasma Physics, Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Jaspers, R. J. E. [Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Park, H. K. [POSTECH, Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Munsat, T. [University of Colorado, Boulder, Colorado 80309 (United States)

2010-10-15

227

Nodal integral method for the neutron diffusion equation in cylindrical geometry  

SciTech Connect

The nodal methodology is based on retaining a higher a higher degree of analyticity in the process of deriving the discrete-variable equations compared to conventional numerical methods. As a result, extensive numerical testing of nodal methods developed for a wide variety of partial differential equations and comparison of the results to conventional methods have established the superior accuracy of nodal methods on coarse meshes. Moreover, these tests have shown that nodal methods are more computationally efficient than finite difference and finite-element methods in the sense that they require shorter CPU times to achieve comparable accuracy in the solutions. However, nodal formalisms and the final discrete-variable equations they produce are, in general, more complicated than their conventional counterparts. This, together with anticipated difficulties in applying the transverse-averaging procedure in curvilinear coordinates, has limited the applications of nodal methods, so far, to Cartesian geometry, and with additional approximations to hexagonal geometry. In this paper the authors report recent progress in deriving and numerically implementing a nodal integral method (NIM) for solving the neutron diffusion equation in cylindrical r-z geometry. Also, presented are comparisons of numerical solutions to two test problems with those obtained by the Exterminator-2 code, which indicate the superior accuracy of the nodal integral method solutions on much coarser meshes.

Azmy, Y.Y.

1987-01-01

228

Long ranged interactions in computer simulations and for quasi-2D systems  

NASA Astrophysics Data System (ADS)

Taking correctly into account long ranged interactions in molecular simulations of molecular models based on classical atomistic representations are essential to obtain reliable results on model systems and in simulations of biological systems. A lot of numerical methods have been developed to this end; the most important of them are reviewed in this paper. Particular attention is paid to the analytical relations between the methods, this allows comparisons on efficiency and accuracy between them and also to proceed to precise implementations of these techniques. While most of the methods have been developed for Coulomb interactions, we give also some analytical details to apply these methods to screened Coulomb (Yukawa interactions), inverse power law and dipolar interactions. Particular types of systems, the quasi-2D systems, are also considered in this paper. Quasi-2D systems represent a large class of physical systems where the spatial extension in one direction of the space is very small by comparison to the other two. These representations are very useful to describe the properties of interfaces, surfaces, fluids confined in slab geometry, etc. In computer simulations, these systems are studied with partial periodic boundary conditions: periodic boundary conditions are taken in directions where spatial extensions are large and some other boundary conditions are taken in directions with smaller extensions. In this review, we describe also the numerical methods developed to handle long ranged interactions in numerical simulations of quasi-2D systems. The properties of quasi-2D systems depend strongly on interactions between components; more specifically electrostatic and magnetic interactions and interactions with external fields are of particular interest in these systems.

Mazars, Martial

2011-03-01

229

Solid-state single-crystal-to-single-crystal transformation from a 2D layer to a 3D framework mediated by lattice iodine release.  

PubMed

We describe an exceedingly rare example of solid-state single-crystal-to-single-crystal transformation from a 2D layer to a known 3D framework via lattice iodine release, which involves the formation of a new Cu-O ligand bond and a change in the metal coordination geometry. PMID:22785388

He, Yuan-Chun; Yang, Jin; Yang, Guo-Cheng; Kan, Wei-Qiu; Ma, Jian-Fang

2012-07-02

230

Anticoagulant Citrate Phosphate Double Dextrose (CP2D) & ...  

Center for Biologics Evaluation and Research (CBER)

... Approved Products. New Drug Applications (NDAs). -. Anticoagulant Citrate Phosphate Double Dextrose (CP2D) & Additive Solution 3 (AS-3). ... More results from www.fda.gov/biologicsbloodvaccines/bloodbloodproducts/approvedproducts

231

2-D real time polarimetric spectrograph with 64-channel.  

NASA Astrophysics Data System (ADS)

A brief description of the multichannel birefringent filter and its three types is provided. A 2-D real time polarimetric spectrograph with 64-channel, an achromatic KD'P modulator, and an automatic supplement system for temperature change, are introduced.

Ai, Guoxiang

1991-01-01

232

Efficient framework for deformable 2D-3D registration  

NASA Astrophysics Data System (ADS)

Using 2D-3D registration it is possible to extract the body transformation between the coordinate systems of X-ray and volumetric CT images. Our initial motivation is the improvement of accuracy of external beam radiation therapy, an effective method for treating cancer, where CT data play a central role in radiation treatment planning. Rigid body transformation is used to compute the correct patient setup. The drawback of such approaches is that the rigidity assumption on the imaged object is not valid for most of the patient cases, mainly due to respiratory motion. In the present work, we address this limitation by proposing a flexible framework for deformable 2D-3D registration consisting of a learning phase incorporating 4D CT data sets and hardware accelerated free form DRR generation, 2D motion computation, and 2D-3D back projection.

Fluck, Oliver; Aharon, Shmuel; Khamene, Ali

2008-04-01

233

Constrained 3D navigation with 2D controllers  

Microsoft Academic Search

Navigation through 3D spaces is required in many interactive graphics and virtual reality applications. The authors consider the subclass of situations in which a 2D device such as a mouse controls smooth movements among viewpoints for a \\

Andrew J. Hanson; Eric A. Wernert

1997-01-01

234

Constrained 3D navigation with 2D controllers  

Microsoft Academic Search

Navigation through 3D spaces is required in many interactive graphics and virtual reality applications. We consider the subclass of situations in which a 2D device such as a mouse controls smooth movements among viewpoints for a \\

Andrew J. Hanson; Eric A. Wernert

1997-01-01

235

POISS2: A 2D Poisson Smoother of Structured Grids.  

National Technical Information Service (NTIS)

A 2D elliptic grid smoother has been developed. The smoother is based on solving two Poisson equations, one for each curvilinear direction. The Poisson equations formed on the physical region are first transformed to the computational (rectilinear) region...

R. Lehtimaeki

1992-01-01

236

Intensity-invariant 2D+T acoustic boundary detection  

Microsoft Academic Search

The authors address the problem of spatio-temporal acoustic boundary detection in echocardiography. They propose a phase-based feature detection method to be used as the front end to higher-level 2D+T\\/3D+T reconstruction algorithms. They develop a 2D+T version of this algorithm and illustrate its performance on some typical echocardiogram sequences. They show how their temporal-based algorithm helps to reduce the number of

Miguel Mulet-Parada; J. Alison Noble

1998-01-01

237

2D-3D face matching using CCA  

Microsoft Academic Search

In recent years, 3D face recognition has obtained much attention. Using 2D face image as probe and 3D face data as gallery is an alternative method to deal with computation complexity, expensive equipment and fussy pretreatment in 3D face recognition systems. In this paper we propose a learning based 2D-3D face matching method using the CCA to learn the mapping

Weilong Yang; Dong Yi; Zhen Lei; Jitao Sang; Stan Z. Li

2008-01-01

238

2dF grows up: Echidna for the AAT  

Microsoft Academic Search

We present the concept design of a new fibre positioner and spectrograph system for the Anglo-Australian Telescope, as a proposed enhancement to the Anglo-Australian Observatory's well-known 2dF facility. A four-fold multiplex enhancement is accomplished by replacing the 400-fibre 2dF fibre positioning robot with a 1600-fibre Echidna unit, feeding three clones of the AAOmega optical spectrograph. Such a facility has the

Andrew McGrath; Sam Barden; Stan Miziarski; William Rambold; Greg Smith

2008-01-01

239

2D Vessel Segmentation Using Local Adaptive Contrast Enhancement  

Microsoft Academic Search

\\u000a 2D vessel segmentation algorithms working on 2D digital subtraction angiography (DSA) images suffer from inhomogeneous contrast\\u000a agent distributions within the vessels. In this work, we present a novel semi-automatic vessel segmentation method based on\\u000a local adaptive contrast enhancement. Either a forward projected 3D centerline or a set of manual selected seed points define\\u000a the vessel branches to be segmented on

Dominik Schuldhaus; Martin Spiegel; Thomas Redel; Maria Polyanskaya; Tobias Struffert; Joachim Hornegger; Arnd Doerfler

240

Bose-Einstein Condensation in Quasi2D Trapped Gases  

Microsoft Academic Search

We discuss Bose-Einstein condensation (BEC) in quasi-2D trapped gases and find that well below the transition temperature Tc the equilibrium state is a true condensate, whereas at intermediate temperatures T2D gas is sensitive to the frequency omega0 of the (tight) confinement in the ``frozen'' direction, and

D. S. Petrov; M. Holzmann; G. V. Shlyapnikov

2000-01-01

241

Standardized evaluation methodology for 2-D-3-D registration  

Microsoft Academic Search

In the past few years, a number of two-dimensional (2-D) to three-dimensional (3-D) (2-D-3-D) registration algorithms have been introduced. However, these methods have been developed and evaluated for specific applications, and have not been directly compared. Understanding and evaluating their performance is therefore an open and important issue. To address this challenge we introduce a standardized evaluation methodology, which can

Everine B. Van De Kraats; Graeme P. Penney; Dejan Tomazevic; Theo Van Walsum; Wiro J. Niessen

2005-01-01

242

Codeine Intoxication Associated with Ultrarapid CYP2D6 Metabolism  

Microsoft Academic Search

Life-threatening opioid intoxication developed in a patient after he was given small doses of codeine for the treatment of a cough associated with bilateral pneumonia. Co- deine is bioactivated by CYP2D6 into morphine, which then undergoes further glucu- ronidation. CYP2D6 genotyping showed that the patient had three or more functional alleles, a finding consistent with ultrarapid metabolism of codeine. We

Yvan Gasche; Youssef Daali; Marc Fathi; Alberto Chiappe; Silvia Cottini; Pierre Dayer; Jules Desmeules

2004-01-01

243

Lossless image compression using 2D allpass filters  

Microsoft Academic Search

In this paper, a reversible integer-to-integer wavelet transform based on non-separable 2D allpass filters is proposed for lossless image coding. The number of rounding operations included in the reversible wavelet transform is reduced by using non-separable 2D allpass filters, thus it is expected to get better coding performance. The lossless coding performance of the proposed reversible wavelet transform is evaluated

Xi Zhang; Kosuke Ohno

2008-01-01

244

An automated pipeline to screen membrane protein 2D crystallization  

Microsoft Academic Search

Electron crystallography relies on electron cryomicroscopy of two-dimensional (2D) crystals and is particularly well suited\\u000a for studying the structure of membrane proteins in their native lipid bilayer environment. To obtain 2D crystals from purified\\u000a membrane proteins, the detergent in a protein–lipid–detergent ternary mixture must be removed, generally by dialysis, under\\u000a conditions favoring reconstitution into proteoliposomes and formation of well-ordered lattices.

Changki Kim; Martin Vink; Minghui Hu; James Love; David L. Stokes; Iban Ubarretxena-Belandia

2010-01-01

245

The Anglo-Australian Observatory 2dF facility  

Microsoft Academic Search

The 2dF (Two-degree Field) facility at the prime focus of the Anglo-Australian Telescope provides multiple-object spectroscopy over a 2° field of view. Up to 400 target fibres can be independently positioned by a complex robot. Two spectrographs provide spectra with resolutions of between 500 and 2000, over wavelength ranges of 440 and 110nm respectively. The 2dF facility began routine observations

I. J. Lewis; R. D. Cannon; K. Taylor; K. Glazebrook; J. A. Bailey; I. K. Baldry; J. R. Barton; T. J. Bridges; G. B. Dalton; T. J. Farrell; P. M. Gray; A. Lankshear; C. McCowage; I. R. Parry; R. M. Sharples; K. Shortridge; G. A. Smith; J. Stevenson; J. O. Straede; L. G. Waller; J. D. Whittard; J. K. Wilcox; K. C. Willis

2002-01-01

246

Mitochondrial Haplogroup U2d Phylogeny and Distribution  

Microsoft Academic Search

The sequencing of the entire mitochondrial DNA belonging to haplogroup U2d reveals that this clade is defined by four coding-region mutations at positions 1700, 4025, 11893, and 14926. Phylogenetic analysis suggests that western Eurasian haplogroup U2d appears to be a sister clade with the Indo-Pakistani haplogroup U2c. Results of a phylogeographic analysis of published population data on the distribution of

Boris Malyarchuk; Miroslava Derenko; Maria Perkova; Tomas Vanecek

2008-01-01

247

A geometry-based error estimation for cross-ratios  

Microsoft Academic Search

For choosing specific cross-ratios as 2D projective coordinates in various computer vision applications, a reasonable error analysis model is usually required. This investigation adopts the assumption of normal distribution for positioning errors of point features in an image to formulate the error variances of cross-ratios. Based on a geometry-based error analysis, a straightforward way of identifying the cross-ratios with minimum

Jain-shing Liu; Jen-hui Chuang

2002-01-01

248

Geometry of thermodynamic control.  

PubMed

A deeper understanding of nonequilibrium phenomena is needed to reveal the principles governing natural and synthetic molecular machines. Recent work has shown that when a thermodynamic system is driven from equilibrium then, in the linear response regime, the space of controllable parameters has a Riemannian geometry induced by a generalized friction tensor. We exploit this geometric insight to construct closed-form expressions for minimal-dissipation protocols for a particle diffusing in a one-dimensional harmonic potential, where the spring constant, inverse temperature, and trap location are adjusted simultaneously. These optimal protocols are geodesics on the Riemannian manifold and reveal that this simple model has a surprisingly rich geometry. We test these optimal protocols via a numerical implementation of the Fokker-Planck equation and demonstrate that the friction tensor arises naturally from a first-order expansion in temporal derivatives of the control parameters, without appealing directly to linear response theory. PMID:23214570

Zulkowski, Patrick R; Sivak, David A; Crooks, Gavin E; DeWeese, Michael R

2012-10-26

249

Geometry of thermodynamic control  

NASA Astrophysics Data System (ADS)

A fundamental problem in modern thermodynamics is how a molecular-scale machine performs useful work, while operating away from thermal equilibrium without excessive dissipation. We show that when a thermodynamic system is driven from equilibrium, in the linear response regime, the space of controllable parameters has a Riemannian geometry induced by a generalized friction tensor. This metric structure controls the dissipation of finite-time transformations, and bestows optimal protocols (geodesics on the Riemannian manifold) with many useful properties. We exploit this geometric insight to construct closed-form expressions for minimal-dissipation protocols for a model system of a particle diffusing in a one-dimensional harmonic potential, where the spring constant, inverse temperature, and trap location are adjusted simultaneously. This simple model has a surprisingly rich geometry, which we test via a numerical implementation of the Fokker-Planck equation.

Sivak, David; Zulkowski, Patrick; Deweese, Michael; Crooks, Gavin

2013-03-01

250

Inflation in warped geometries  

NASA Astrophysics Data System (ADS)

We argue that brane anti-brane inflation in string theory de-Sitter vacua of Kachru-Kallosh-Linde-Trivedi (KKLT) is captured by the dynamics of a D3-brane probe in the local KKLT model constructed in hep-th/0203041. This provides a framework to study in a controllable way corrections to the inflationary slow roll parameter ? due to conformal symmetry breaking in a warped geometry throat. We compute the leading correction to ? for the inflation in the Klebanov-Tseytlin throat geometry. We find that in certain regime this correction tends to decrease ?. Computations in a different regime suggest however that it is unlikely that ?<<1 can be achieved with the D3-brane throat inflation.

Buchel, Alex; Roiban, Radu

2004-06-01

251

State Sums and Geometry  

NASA Astrophysics Data System (ADS)

In this thesis I review the definition of topological quantum field theories through state sums on triangulated manifolds. I describe the construction of state sum invariants of 3-manifolds from a graphical calculus and show how to evaluate the invariants as boundary amplitudes. I review how to define such a graphical calculus through SU(2) representation theory. I then review various geometricity results for the representation theory of SU(2), Spin(4) and SL(2,C), and define coherent boundary manifolds for state sums based on these representations. I derive the asymptotic geometry of the SU(2) based Ponzano-Regge invariant in three dimensions, and the SU(2) based Ooguri models amplitude in four dimensions. As a corollary to the latter results I derive the asymptotic behaviour of various recently proposed spin foam models motivated from the Plebanski formulation of general relativity. Finally the asymptotic geometry of the SL(2,C) based model is derived.

Hellmann, Frank

2011-02-01

252

Brane Universe: Global Geometry  

SciTech Connect

The global geometries of bulk vacuum space-times in the brane-universe models are investigated and classified in terms of geometrical invariants. The corresponding Carter-Penrose diagrams and embedding diagrams are constructed. It is shown that for a given energy-momentum induced on the brane there can be different types of global geometries depending on the signs of a bulk cosmological term and surface energy density of the brane (the sign of the latter does not influence the internal cosmological evolution). It is shown that in the Randall-Sundrum scenario it is possible to have an asymmetric hierarchy splitting even with a Z{sub 2}-symmetric matching of 'our' brane to the bulk.

Berezin, Victor [Institute for Nuclear Research, Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, 117312, Moscow (Russian Federation)

2010-06-23

253

Multilevel geometry optimization  

SciTech Connect

Geometry optimization has been carried out for three test molecules using six multilevel electronic structure methods, in particular Gaussian-2, Gaussian-3, multicoefficient G2, multicoefficient G3, and two multicoefficient correlation methods based on correlation-consistent basis sets. In the Gaussian-2 and Gaussian-3 methods, various levels are added and subtracted with unit coefficients, whereas the multicoefficient Gaussian-x methods involve noninteger parameters as coefficients. The multilevel optimizations drop the average error in the geometry (averaged over the 18 cases) by a factor of about two when compared to the single most expensive component of a given multilevel calculation, and in all 18 cases the accuracy of the atomization energy for the three test molecules improves; with an average improvement of 16.7 kcal/mol. (c) 2000 American Institute of Physics.

Rodgers, Jocelyn M. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States); Fast, Patton L. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States); Truhlar, Donald G. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States)

2000-02-15

254

Geometry of thermodynamic control  

NASA Astrophysics Data System (ADS)

A deeper understanding of nonequilibrium phenomena is needed to reveal the principles governing natural and synthetic molecular machines. Recent work has shown that when a thermodynamic system is driven from equilibrium then, in the linear response regime, the space of controllable parameters has a Riemannian geometry induced by a generalized friction tensor. We exploit this geometric insight to construct closed-form expressions for minimal-dissipation protocols for a particle diffusing in a one-dimensional harmonic potential, where the spring constant, inverse temperature, and trap location are adjusted simultaneously. These optimal protocols are geodesics on the Riemannian manifold and reveal that this simple model has a surprisingly rich geometry. We test these optimal protocols via a numerical implementation of the Fokker-Planck equation and demonstrate that the friction tensor arises naturally from a first-order expansion in temporal derivatives of the control parameters, without appealing directly to linear response theory.

Zulkowski, Patrick R.; Sivak, David A.; Crooks, Gavin E.; DeWeese, Michael R.

2012-10-01

255

Codes on finite geometries  

Microsoft Academic Search

New algebraic methods for constructing codes based on hyperplanes of two different dimensions in finite geometries are presented. The new construction methods result in a class of multistep majority-logic decodable codes and three classes of low-density parity-check (LDPC) codes. Decoding methods for the class of majority-logic decodable codes, and a class of codes that perform well with iterative decoding in

Heng Tang; Jun Xu; Shu Lin; Khaled A. S. Abdel-ghaffar

2005-01-01

256

Geometry Constructions Language  

Microsoft Academic Search

Geometry Constructions Language (gcl) is a language for explicit descriptions of constructions in Euclidean plane and of their properties. Other mathematical\\u000a objects can also be described in the language. The language gcl is intuitive and simple, yet it supports arrays, flow control structures, user-defined procedures, etc. The processors for\\u000a the gcl language—applications gclc and Wingclc—enable visualization of described objects and

Predrag Janicic

2010-01-01

257

Genetic polymorphisms of cytochrome P450 2D6 (CYP2D6): clinical consequences, evolutionary aspects and functional diversity  

Microsoft Academic Search

CYP2D6 is of great importance for the metabolism of clinically used drugs and about 20–25% of those are metabolised by this enzyme. In addition, the enzyme utilises hydroxytryptamines as endogenous substrates. The polymorphism of the enzyme results in poor, intermediate, efficient or ultrarapid metabolisers (UMs) of CYP2D6 drugs. It is plausible that the UM genotype, where more than one active

M Ingelman-Sundberg

2005-01-01

258

A Nonrigid Kernel-Based Framework for 2D-3D Pose Estimation and 2D Image Segmentation  

Microsoft Academic Search

In this work, we present a nonrigid approach to jointly solving the tasks of 2D-3D pose estimation and 2D image segmentation. In general, most frameworks that couple both pose estimation and segmentation assume that one has exact knowledge of the 3D object. However, under nonideal conditions, this assumption may be violated if only a general class to which a given

Romeil Sandhu; Samuel Dambreville; Anthony J. Yezzi; Allen Tannenbaum

2011-01-01

259

Grade 2 Practice Problems: Geometry  

NSDL National Science Digital Library

This page contains 20 problems in geometry from the Port Angeles School District in Washington state. Links to state GLEs and revised standards are provided. Topics covered include shape in plane and solid geometry, bilateral symmetry, and logic.

2011-01-01

260

Circumference of Taxicab Geometry Circles.  

ERIC Educational Resources Information Center

Presented is an activity in which students apply familiar concepts of geometry to novel settings. Using square dot paper and isometric dot paper, students trace routes and determine the geometry of each circle. (KR)

Litwiller, Bonnie H.; Duncan, David R.

1991-01-01

261

Graphical debugging of combinational geometry.  

National Technical Information Service (NTIS)

A graphical debugger for combinatorial geometry being developed at Oak Ridge National Laboratory is described. The prototype debugger consists of two parts: a FORTRAN-based ''view'' generator and a Microsoft Windows application for displaying the geometry...

T. J. Burns M. S. Smith

1992-01-01

262

Geometry Is More Than Proof.  

ERIC Educational Resources Information Center

|Five basic skill areas needing more attention in standard high school geometry are discussed. Levels of student mental development in geometry and a need for less emphasis on formal proofs are reviewed. (MP)|

Hoffer, Alan

1981-01-01

263

RATIONAL CURVES AND PARABOLIC GEOMETRIES  

Microsoft Academic Search

The twistor transform of a parabolic geometry has two steps: lift up to a geometry of higher dimension, and then drop to a geometry of lower dimension. The rst step is a functor, but the second requires some compati- bility conditions. Local necessary conditions were uncovered by Andreas Cap (14). I prove necessary and sucient global conditions for complex parabolic

BENJAMIN MCKAY

264

2D/3D switchable LCD monitor with chromatic separation  

NASA Astrophysics Data System (ADS)

The 2D/3D switchable LCD stereoscopic display is based on the method of chromatic stereoscopic frame separation that occurs between the left and right eye with the use of two spectrally independent backlight sources with primary color sets RGBLeft and RGBRigth. Semiconductor lasers and/or LEDs with narrow band spectral filters could be used as backlight sources. In a 3D mode, the RGB sources illuminate alternatively and synchronously with the alternative displaying of stereo pair frames. Glasses with chromatic filters are used for watching in 3D mode and separate light from two RGB sources between the eyes of the viewer and in that way separate stereoscopic frames. In a 2D mode, any one of the RGB sources would work. In this case, the display looks like an ordinary display. Two RGB sources could be used for color enhancement in 2D mode. The quality of the images in 3D mode is the same as in 2D. Frame frequency is two times less in 3D mode as compared to 2D. The suggested method competes with two known methods for LCD that use glasses: "Shutter-Glasses Method" and "Polarization Method." It has certain advantages: image quality and stereo channel separation are independent from viewing angle or head tilt of viewer, and there are no active components in the glasses.

Gaskevich, Evgeny B.

2010-02-01

265

Automatic Detection of 2D and 3D Lung Nodules in Chest Spiral CT Scans  

PubMed Central

Automatic detection of lung nodules is an important problem in computer analysis of chest radiographs. In this paper, we propose a novel algorithm for isolating lung abnormalities (nodules) from spiral chest low-dose CT (LDCT) scans. The proposed algorithm consists of three main steps. The first step isolates the lung nodules, arteries, veins, bronchi, and bronchioles from the surrounding anatomical structures. The second step detects lung nodules using deformable 3D and 2D templates describing typical geometry and gray-level distribution within the nodules of the same type. The detection combines the normalized cross-correlation template matching and a genetic optimization algorithm. The final step eliminates the false positive nodules (FPNs) using three features that robustly define the true lung nodules. Experiments with 200?CT data sets show that the proposed approach provided comparable results with respect to the experts.

El-Baz, Ayman; Elnakib, Ahmed; Abou El-Ghar, Mohamed; Gimel'farb, Georgy; Falk, Robert; Farag, Aly

2013-01-01

266

An Integrative Model of Excitation Driven Fluid Flow in a 2D Uterine Channel  

NASA Astrophysics Data System (ADS)

We present a model of intra-uterine fluid flow in a sagittal cross-section of the uterus by inducing peristalsis in a 2D channel. This is an integrative multiscale computational model that takes as input fluid viscosity, passive tissue properties of the uterine channel and a prescribed wave of membrane depolarization. This voltage pulse is coupled to a model of calcium dynamics inside a uterine smooth muscle cell, which in turn drives a kinetic model of myosin phosphorylation governing contractile muscle forces. Using the immersed boundary method, these muscle forces are communicated to a fluid domain to simulate the contractions which occur in a human uterus. An analysis of the effects of model parameters on the flow properties and emergent geometry of the peristaltic channel will be presented.

Maggio, Charles; Fauci, Lisa; Chrispell, John

2009-11-01

267

2D non-LTE modeling for axisymmetric winds. Method and test cases  

NASA Astrophysics Data System (ADS)

Aims.This paper describes a code which is capable of modeling axisymmetric stellar winds. Methods: .At present the code uses a short characteristic technique for the continuum transfer, while bound-bound transitions are treated using the Sobolev approximation. The simultaneous solution of the transfer equations, and the equations of statistical equilibrium, is achieved by a combination of preconditioning and linearization. Results: .Extensive tests were performed which show that, in the extreme conditions of gray opacity or spherical symmetry, the code performs similar to other established codes. Simple 2D tests have been undertaken which confirm the performance of the code, and serve to illustrate simple effects that can occur in axisymmetric stellar winds. The code has been designed with flexibility in mind, with the radiation transport section treated, as far as possible, distinctly from the solution of the statistical equilibrium and energy balance equations. This will facilitate the inclusion of other transport solvers, and the treatment of more complex geometries.

Georgiev, L. N.; Hillier, D. J.; Zsargó, J.

2006-11-01

268

Symmetrized compact scheme for receptivity study of 2D transitional channel flow  

NASA Astrophysics Data System (ADS)

In many physical problems, one must maintain symmetry of numerical schemes the symmetry arising due to geometry and/or physical conditions defining the flow. The direct simulation of transitional plane Poiseuille flow presents one such case, that motivated the present study. It has been shown here, using the method of analyzing non-periodic problems in Sengupta et al. (2003), that compact and other high accuracy schemes display strong directionality of the algorithm and such methods cannot be used for direct simulation of the physical flow. This prevalent, but unacceptable situation for DNS is rectified in the present work and a new scheme is introduced that prevents this asymmetry from contaminating results. The simulated transitional flow past 2D channel here, using the new scheme, are in agreement with experimental results and other recent views of sub-critical instabilities.

Dipankar, A.; Sengupta, T. K.

2006-06-01

269

The transition matrix method for a 2D eddy current interaction problem  

NASA Astrophysics Data System (ADS)

A 2D model of the eddy current interaction problem that consists of an inhomogeneity in a conductive half space is presented. The applied analytical method of solution is the transition (T) matrix method. This involves use of the free space Green's function to generate a system of boundary integral relations. In this way, it is easy to identify the contributions to the total solution from each different scattering surface. The different parts are separated also in the computation of the impedance. This leads to low cost simulations in terms of computation time and qualify the method to be used to obtain probability of detection (POD) curves. The T matrix method is a building block method and the possibility to extend the geometry with several inhomogeneities and extra layers will be discussed. The model is compared with a Finite Element (FE) model and numerical examples for the case with a cylindrical inhomogeneity are given.

Larsson, Lars; Rosell, Anders

2012-05-01

270

2D divertor design calculations for the Nataional High-power Advanced Torus Experiment  

SciTech Connect

The National High Power Advanced Torus Experiment is a concept for a new facility to address the FESAC Theme of "Taming the Plasma-Material Interface." This concept exploits the compactness and excellent access provided by low aspect ratio to achieve a high ratio of exhaust power to major radius in order to study the integration of high-performance, long-pulse plasmas with a reactor-relevant high heat flux plasma boundary. Predictions of the scrape-off-layer plasma characteristics are presented, as calculated with the 2D edge modeling code SOLPS. Calculations in a variety of magnetic geometries indicate that very high levels of divertor heat flux can be expected, with peak values far in excess of the power handling capabilities of presently-used materials. Possible methods to reduce the heat flux to acceptable levels are discussed.

Canik, John [ORNL; Maingi, R. [Oak Ridge National Laboratory (ORNL); Owen, Larry W [ORNL; Menard, J. [Princeton Plasma Physics Laboratory (PPPL); Goldston, R. [Princeton Plasma Physics Laboratory (PPPL); Kotschenreuther, M. [University of Texas, Austin; Valanju, P. [University of Texas, Austin; Mahajan, S. [University of Texas, Austin

2009-01-01

271

Phase Mixing of Alfvén Waves Near a 2D Magnetic Null Point  

NASA Astrophysics Data System (ADS)

The propagation of linear Alfvén wave pulses in an inhomogeneous plasma near a 2D coronal null point is investigated. When a uniform plasma density is considered, it is seen that an initially planar Alfvén wavefront remains planar, despite the varying equilibrium Alfvén speed, and that all the wave collects at the separatrices. Thus, in the non-ideal case, these Alfvénic disturbances preferentially dissipate their energy at these locations. For a non-uniform equilibrium density, it is found that the Alfvén wavefront is significantly distorted away from the initially planar geometry, inviting the possibility of dissipation due to phase mixing. Despite this however, we conclude that for the Alfvén wave, current density accumulation and preferential heating still primarily occur at the separatrices, even when an extremely non-uniform density profile is considered.

McLaughlin, J. A.

2013-09-01

272

2D full wave modeling for a synthetic Doppler backscattering diagnostic  

SciTech Connect

Doppler backscattering (DBS) is a plasma diagnostic used in tokamaks and other magnetic confinement devices to measure the fluctuation level of intermediate wavenumber (k{sub {theta}}{rho}{sub s}{approx} 1) density fluctuations and the lab frame propagation velocity of turbulence. Here, a synthetic DBS diagnostic is described, which has been used for comparisons between measurements in the DIII-D tokamak and predictions from nonlinear gyrokinetic simulations. To estimate the wavenumber range to which a Gaussian beam would be sensitive, a ray tracing code and a 2D finite difference, time domain full wave code are used. Experimental density profiles and magnetic geometry are used along with the experimental antenna and beam characteristics. An example of the effect of the synthetic diagnostic on the output of a nonlinear gyrokinetic simulation is presented.

Hillesheim, J. C.; Schmitz, L.; Kubota, S.; Rhodes, T. L.; Carter, T. A. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); Holland, C. [University of California, San Diego, La Jolla, California 92093 (United States)

2012-10-15

273

2D full wave modeling for a synthetic Doppler backscattering diagnostic  

NASA Astrophysics Data System (ADS)

Doppler backscattering (DBS) is a plasma diagnostic used in tokamaks and other magnetic confinement devices to measure the fluctuation level of intermediate wavenumber (k??s ~ 1) density fluctuations and the lab frame propagation velocity of turbulence. Here, a synthetic DBS diagnostic is described, which has been used for comparisons between measurements in the DIII-D tokamak and predictions from nonlinear gyrokinetic simulations. To estimate the wavenumber range to which a Gaussian beam would be sensitive, a ray tracing code and a 2D finite difference, time domain full wave code are used. Experimental density profiles and magnetic geometry are used along with the experimental antenna and beam characteristics. An example of the effect of the synthetic diagnostic on the output of a nonlinear gyrokinetic simulation is presented.

Hillesheim, J. C.; Holland, C.; Schmitz, L.; Kubota, S.; Rhodes, T. L.; Carter, T. A.

2012-10-01

274

2D-CELL: image processing software for extraction and analysis of 2-dimensional cellular structures  

NASA Astrophysics Data System (ADS)

2D-CELL is a software package for the processing and analyzing of photographic images of cellular structures in a largely interactive way. Starting from a binary digitized image, the programs extract the line network (skeleton) of the structure and determine the graph representation that best models it. Provision is made for manually correcting defects such as incorrect node positions or dangling bonds. Then a suitable algorithm retrieves polygonal contours which define individual cells - local boundary curvatures are neglected for simplicity. Using elementary analytical geometry relations, a range of metric and topological parameters describing the population are then computed, organized into statistical distributions and graphically displayed. Presently at: LSG2M-URA159-Ecole des Mines, 54000 Nancy, France.

Righetti, F.; Telley, H.; Leibling, Th. M.; Mocellin, A.

1992-01-01

275

Azimuthal reorientation of pentacene upon 2D condensation.  

PubMed

We report a novel two-dimensional gas-solid phase transition of pentacene molecules on the Cu(110)-(2 × 1)O surface where the 2D condensation is accompanied by a reversible azimuthal rotation of the pentacene molecules. The change of the optical anisotropy associated with this reorientation allows us to explore the 2D condensation as a function of coverage and temperature by reflectance difference spectroscopy. As a result, the 2D heat of condensation of pentacene on Cu(110)-(2 × 1)O is determined to be 84 meV, which is more than one order of magnitude smaller than the respective value for 3D crystallization. PMID:23521273

Sun, L D; Gall, J; Weidlinger, G; Liu, C Y; Denk, M; Zeppenfeld, P

2013-03-06

276

Diffusion Limited Aggregation in Continuous 2D Space Model  

NSDL National Science Digital Library

The Diffusion Limited Aggregation in Continuous 2D Space Model simulates the formation of a cluster using a random-walk process called "diffusion limited aggregation" (DLA). The cluster formed by this process is an example of a fractal, and the simulation can be extended to calculate and analyze the fractal dimension. The Diffusion Limited Aggregation in Continuous 2D Space Model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_fmu_DLA_continuous_2D.jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item.

Engelhardt, Larry

2012-01-07

277

Real-Time 2-D Temperature Imaging Using Ultrasound  

PubMed Central

We have previously introduced methods for noninvasive estimation of temperature change using diagnostic ultrasound. The basic principle was validated both in vitro and in vivo by several groups worldwide. Some limitations remain, however, that have prevented these methods from being adopted in monitoring and guidance of minimally invasive thermal therapies, e.g., RF ablation and high-intensity-focused ultrasound (HIFU). In this letter, we present first results from a real-time system for 2-D imaging of temperature change using pulse-echo ultrasound. The front end of the system is a commercially available scanner equipped with a research interface, which allows the control of imaging sequence and access to the RF data in real time. A high-frame-rate 2-D RF acquisition mode, M2D, is used to capture the transients of tissue motion/deformations in response to pulsed HIFU. The M2D RF data is streamlined to the back end of the system, where a 2-D temperature imaging algorithm based on speckle tracking is implemented on a graphics processing unit. The real-time images of temperature change are computed on the same spatial and temporal grid of the M2D RF data, i.e., no decimation. Verification of the algorithm was performed by monitoring localized HIFU-induced heating of a tissue-mimicking elastography phantom. These results clearly demonstrate the repeatability and sensitivity of the algorithm. Furthermore, we present in vitro results demonstrating the possible use of this algorithm for imaging changes in tissue parameters due to HIFU-induced lesions. These results clearly demonstrate the value of the real-time data streaming and processing in monitoring, and guidance of minimally invasive thermotherapy.

Liu, Dalong; Ebbini, Emad S.

2010-01-01

278

Proterozoic Geomagnetic Field Geometry  

NASA Astrophysics Data System (ADS)

Pre-Mesozoic continental reconstructions and paleoclimatic inferences from paleomagnetism rely critically upon the assumption of a time-averaged geocentric axial dipole (GAD) magnetic field. We have been testing the GAD assumption and localized non-dipole components in a different manner, by observing directional variations within the Matachewan, Mackenzie and Franklin dyke swarms. Large dyke swarms, commonly emplaced within a few million years, provide the necessary broad areal coverage to perform a test of global geomagnetic field geometry. Our analysis varies the quadrupole and octupole values of the generalized paleolatitude equation to determine a minimal angular dispersion and maximum precision of paleopoles from each dyke swarm. As a control, paleomagnetic data from the central Atlantic magmatic province (CAMP) show the sensitivities of our method to non-GAD contributions to the ancient geomagnetic field. Within the uncertainties, CAMP data are consistent with independent estimates of non-GAD contributions derived from global tectonic reconstructions (Torsvik & Van der Voo, 2002). Current results from the three Proterozoic dyke swarms all have best fits that are non-dipolar, but they differ in their optimal quadrupole/ octupole components. Treated together under the hypothesis of a static Proterozoic field geometry, the data allow a pure GAD geodynamo within the uncertainty of the method. Current results were performed using Fisherian statistics, but Bingham statistics will be included to account for the ellipticity of data.

Panzik, J. E.; Evans, D. A.

2011-12-01

279

Inequalities detecting quantum entanglement for 2?d systems  

NASA Astrophysics Data System (ADS)

We present a set of inequalities for detecting quantum entanglement of 2?d quantum states. For 2?2 and 2?3 systems, the inequalities give rise to sufficient and necessary separability conditions for both pure and mixed states. For the case of d>3, these inequalities are necessary conditions for separability, which detect all entangled states that are not positive under partial transposition and even some entangled states with positive partial transposition. These inequalities are given by mean values of local observables and present an experimental way of detecting the quantum entanglement of 2?d quantum states and even multiqubit pure states.

Zhao, Ming-Jing; Ma, Teng; Fei, Shao-Ming; Wang, Zhi-Xi

2011-05-01

280

3D Blood Flow Reconstruction from 2D Angiograms  

NASA Astrophysics Data System (ADS)

A method for 3-d blood flow reconstruction is presented. Given a 3-d volume of a vessel tree and a 2-d sequence of angiograms, the propagation information can be back-projected into the 3-d vessel volume. In case of overlapping vessel segments in the 2-d projections, ambiguous back-projection results are obtained. We introduce a probabilistic blood flow model for solving these ambiguities. Based on the last estimated state and known system dynamics the next state is predicted, and predictions are judged by the back-projected information. The discrete realization is done with a particle filter. Experiments prove the efficiency of our method.

Platzer, Esther-S.; Deinzer, Frank; Paulus, Dietrich; Denzler, Joachim

281

Using 2-D arrays for sensing multimodal Lamb waves  

NASA Astrophysics Data System (ADS)

Monitoring structural integrity of large planar structures requires normally a relatively dense network of uniformly distributed ultrasonic sensors. A 2-D ultrasonic phased array with all azimuth angle coverage would be extremely useful for the structural health monitoring (SHM) of such structures. Known techniques for estimating direction of arriving (DOA) waves cannot efficiently cope with dispersive and multimodal Lamb waves (LWs). In the paper we propose an adaptive spectral estimation technique capable of handling broadband LWs sensed by 2-D arrays, the modified Capon method. Performance of the technique is evaluated using simulated multiple-mode LWs, and verified using experimental data.

Engholm, Marcus; Stepinski, Tadeusz

2010-03-01

282

The 2D large deformation analysis using Daubechies wavelet  

NASA Astrophysics Data System (ADS)

In this paper, Daubechies (DB) wavelet is used for solution of 2D large deformation problems. Because the DB wavelet scaling functions are directly used as basis function, no meshes are needed in function approximation. Using the DB wavelet, the solution formulations based on total Lagrangian approach for two-dimensional large deformation problems are established. Due to the lack of Kroneker delta properties in wavelet scaling functions, Lagrange multipliers are used for imposition of boundary condition. Numerical examples of 2D large deformation problems illustrate that this method is effective and stable.

Liu, Yanan; Qin, Fei; Liu, Yinghua; Cen, Zhangzhi

2010-01-01

283

Optical imaging systems analyzed with a 2D template.  

PubMed

Present determination of optical imaging systems specifications are based on performance values and modulation transfer function results carried with a 1D resolution template (such as the USAF resolution target or spoke templates). Such a template allows determining image quality, resolution limit, and contrast. Nevertheless, the conventional 1D template does not provide satisfactory results, since most optical imaging systems handle 2D objects for which imaging system response may be different by virtue of some not readily observable spatial frequencies. In this paper we derive and analyze contrast transfer function results obtained with 1D as well as 2D templates. PMID:22614498

Haim, Harel; Konforti, Naim; Marom, Emanuel

2012-05-10

284

Eulerian Moment Equations for 2-D Stochastic Immiscible Flow  

SciTech Connect

We solve statistical moment differential equations for immiscible flow in porous media in the limit of zero capillary pressure, with application to secondary oil recovery. Closure is achieved by Taylor expansion of the fractional flow function and a perturbation argument. Previous results in 1-D are extended to 2-D are extended to 2-D, in which bimodal profile is less evident. Mean and variance of (water) saturation exhibit a bimodel character; two shocks replace the single shock front evident in the classical Buckley-Leverett saturation profile. Comparison to Monte Carlo simulations (MCS) shows that the moment equations approach gives a good approximation to total oil production.

Jarman, Kenneth D.; Russell, Thomas F.

2003-10-01

285

CH2D+, the Search for the Holy Grail  

NASA Astrophysics Data System (ADS)

CH2D+, the singly deuterated counterpart of CH3+, offers an alternative way to mediate formation of deuterated species at temperatures of several tens of Kelvin, as compared to the release of deuterated species from grains. We report a longstanding observational search for this molecular ion, whose rotational spectroscopy is not yet completely secure. We summarize the main spectroscopic properties of this molecule and discuss the chemical network leading to the formation of CH2D+, with explicit account of the ortho/para forms of H2, H3+, and CH3+. Astrochemical models support the presence of this molecular ion in moderately warm environments at a marginal level.

Roueff, Evelyne; Gerin, Maryvonne; Lis, Dariusz C.; Wootten, Alwyn; Marcelino, Nuria; Cernicharo, Jose; Tercero, Belen

2013-10-01

286

The Anglo-Australian Observatory's 2dF Facility  

Microsoft Academic Search

The 2dF (Two-degree Field) facility at the prime focus of the\\u000aAnglo-Australian Telescope provides multiple object spectroscopy over a 2\\u000adegree field of view. Up to 400 target fibres can be independently positioned\\u000aby a complex robot. Two spectrographs provide spectra with resolutions of\\u000abetween 500 and 2000, over wavelength ranges of 440nm and 110nm respectively.\\u000aThe 2dF facility began

I. J. Lewis; R. D. Cannon; K. Taylor; K. Glazebrook; J. A. Bailey; I. K. Baldry; J. R. Barton; T. J. Bridges; G. B. Dalton; T. J. Farrell; P. M. Gray; A. Lankshear; C. McCowage; I. R. Parry; R. M. Sharples; K. Shortridge; G. A. Smith; J. Stevenson; J. O. Straede; L. G. Waller; J. D. Whittard; J. K. Wilcox; K. C. Willis

2002-01-01

287

How to Use 2D Gel Electrophoresis in Plant Proteomics.  

PubMed

Two-dimensional electrophoresis has nurtured the birth of proteomics. It is however no longer the exclusive setup used in proteomics, with the development of shotgun proteomics techniques that appear more fancy and fashionable nowadays.Nevertheless, 2D gel-based proteomics still has valuable features, and sometimes unique ones, which make it often an attractive choice when a proteomics strategy must be selected. These features are detailed in this chapter, as is the rationale for selecting or not 2D gel-based proteomics as a proteomic strategy. PMID:24136513

Rabilloud, Thierry

2014-01-01

288

Numerical study of diffusion induced transport in 2D systems  

NASA Astrophysics Data System (ADS)

Transport in a two-dimensional (2D) diffusive system with a `ratchet-like' potential is studied. An additive constant force is applied perpendicularly to the direction where the reflection symmetry of the potential is broken. It is demonstrated that a flow of Brownian particles orthogonally to the applied force is induced. Finite element method has been used as a tool for the solution of the corresponding Smoluchowski-equation. The results have been compared to Monte Carlo simulations and show good agreement. We also present the comparison of the 2D system with an 1D flashing ratchet.

Kostur, M.; Schimansky-Geier, L.

2000-02-01

289

Properties of Spitzer c2d dark clouds (Evans+, 2009)  

Microsoft Academic Search

The observations here were all obtained by the c2d project or by GTO observations that we have included in our data. They have been described in the publications given hereafter: Five large clouds were selected for the c2d project: Serpens (Eiroa et al., 2008hsf2.book..693E), Perseus (Bally et al., 2008hsf1.book..308B), Ophiuchus (Wilking et al., 2008hsf2.book..351W), Lupus (Comeron, 2008hsf2.book..295C), and Chamaeleon (Luhman,

N. J. Evans; M. M. Dunham; J. K. Jorgensen; M. L. Enoch; B. Merin; E. F. van Dishoeck; J. M. Alcala; P. C. Myers; K. R. Stapelfeldt; T. L. Huard; L. E. Allen; P. M. Harvey; T. van Kempen; G. A. Blake; D. W. Koerner; L. G. Mundy; D. L. Padgett; A. I. Sargent

2009-01-01

290

COMPARISON OF THE ACCURACY OF VARIOUS SPATIAL DISCRETIZATION SCHEMES OF THE DISCRETE ORDINATES EQUATIONS IN 2D CARTESIAN GEOMETRY  

SciTech Connect

We present a comprehensive error estimation of four spatial discretization schemes of the two-dimensional Discrete Ordinates (SN) equations on Cartesian grids utilizing a Method of Manufactured Solution (MMS) benchmark suite based on variants of Larsen’s benchmark featuring different orders of smoothness of the underlying exact solution. The considered spatial discretization schemes include the arbitrarily high order transport methods of the nodal (AHOTN) and characteristic (AHOTC) types, the discontinuous Galerkin Finite Element method (DGFEM) and the recently proposed higher order diamond difference method (HODD) of spatial expansion orders 0 through 3. While AHOTN and AHOTC rely on approximate analytical solutions of the transport equation within a mesh cell, DGFEM and HODD utilize a polynomial expansion to mimick the angular flux profile across each mesh cell. Intuitively, due to the higher degree of analyticity, we expect AHOTN and AHOTC to feature superior accuracy compared with DGFEM and HODD, but at the price of potentially longer grind times and numerical instabilities. The latter disadvantages can result from the presence of exponential terms evaluated at the cell optical thickness that arise from the semianalytical solution process. This work quantifies the order of accuracy and the magnitude of the error of all four discretization methods for different optical thicknesses, scattering ratios and degrees of smoothness of the underlying exact solutions in order to verify or contradict the aforementioned intuitive expectation.

Sebastian Schunert; Yousry Y. Azmy; Damien Fournier

2011-05-01

291

Symplectic geometry and physics: three introductory lectures.  

NASA Astrophysics Data System (ADS)

Contents: Lecture I: geometry and physics. Lecture II: the occurrence of symplectic geometry in optics and mechanics. Lecture III: three applications of symplectic geometry. Epilog: the cat's paradigm.

Provost, J.-P.

292

Challenging claims of nonjet ``higher harmonic'' components in 2D angular correlations from high-energy heavy-ion collisions  

NASA Astrophysics Data System (ADS)

Background: Possible evidence for triangular flow and other “higher harmonic flows” in high-energy nucleus-nucleus collisions has received much attention recently. It is conjectured that several higher harmonic flows vm may result from initial-state geometry fluctuations in A-A collisions coupled to a radially expanding medium. However, as with “elliptic flow” v2 measurements, nonhydrodynamic mechanisms such as jet production may contribute to other higher azimuth multipoles vm as biases.Purpose: Careful distinctions should be maintained between jet-related and nonjet (possibly hydrodynamic) contributions to vm (e.g., “nonflow” and “flow”). In this study we consider several questions. (a) To what extent do jetlike structures in two-dimensional (2D) angular correlations contribute to azimuth multipoles inferred from various vm methods? (b) If a multipole element is added to a 2D fit model, is a nonzero amplitude indicative of a corresponding flow component? (c) Can 2D correlations establish the necessity of nonjet contributions to some or all higher multipoles?Method: Model fits to 2D angular correlations are used to establish the origins of azimuth multipoles inferred from 1D projections onto azimuth or from nongraphical numerical methods.Results: We find that jetlike angular correlations, and specifically a 2D peak at the angular origin consistent with jet production, constitute the dominant contribution to inferred higher multipoles, and the data do not require higher multipoles in isolation from the jetlike 2D peak.Conclusions: The inference of “higher harmonic flows” results from identifying certain nominally jetlike structures as flow manifestations through unjustified application of 1D Fourier series analysis. Although the peak structure at the angular origin is strongly modified in more-central collisions, some properties remain compatible with relevant pQCD theory expectations for jet production.

Trainor, Thomas A.; Prindle, Duncan J.; Ray, R. L.

2012-12-01

293

What shape are dolphins? Building 3D morphable models from 2D images.  

PubMed

3D morphable models are low-dimensional parameterizations of 3D object classes which provide a powerful means of associating 3D geometry to 2D images. However, morphable models are currently generated from 3D scans, so for general object classes such as animals they are economically and practically infeasible. We show that, given a small amount of user interaction (little more than that required to build a conventional morphable model), there is enough information in a collection of 2D pictures of certain object classes to generate a full 3D morphable model, even in the absence of surface texture. The key restriction is that the object class should not be strongly articulated, and that a very rough rigid model should be provided as an initial estimate of the “mean shape.” The model representation is a linear combination of subdivision surfaces, which we fit to image silhouettes and any identifiable key points using a novel combined continuous-discrete optimization strategy. Results are demonstrated on several natural object classes, and show that models of rather high quality can be obtained from this limited information. PMID:22392707

Cashman, Thomas J; Fitzgibbon, Andrew W

2013-01-01

294

Efficient implementation of the rank correlation merit function for 2D/3D registration.  

PubMed

A growing number of clinical applications using 2D/3D registration have been presented recently. Usually, a digitally reconstructed radiograph is compared iteratively to an x-ray image of the known projection geometry until a match is achieved, thus providing six degrees of freedom of rigid motion which can be used for patient setup in image-guided radiation therapy or computer-assisted interventions. Recently, stochastic rank correlation, a merit function based on Spearman's rank correlation coefficient, was presented as a merit function especially suitable for 2D/3D registration. The advantage of this measure is its robustness against variations in image histogram content and its wide convergence range. The considerable computational expense of computing an ordered rank list is avoided here by comparing randomly chosen subsets of the DRR and reference x-ray. In this work, we show that it is possible to omit the sorting step and to compute the rank correlation coefficient of the full image content as fast as conventional merit functions. Our evaluation of a well-calibrated cadaver phantom also confirms that rank correlation-type merit functions give the most accurate results if large differences in the histogram content for the DRR and the x-ray image are present. PMID:20844334

Figl, M; Bloch, C; Gendrin, C; Weber, C; Pawiro, S A; Hummel, J; Markelj, P; Pernus, F; Bergmann, H; Birkfellner, W

2010-09-16

295

NOTE: Efficient implementation of the rank correlation merit function for 2D/3D registration  

NASA Astrophysics Data System (ADS)

A growing number of clinical applications using 2D/3D registration have been presented recently. Usually, a digitally reconstructed radiograph is compared iteratively to an x-ray image of the known projection geometry until a match is achieved, thus providing six degrees of freedom of rigid motion which can be used for patient setup in image-guided radiation therapy or computer-assisted interventions. Recently, stochastic rank correlation, a merit function based on Spearman's rank correlation coefficient, was presented as a merit function especially suitable for 2D/3D registration. The advantage of this measure is its robustness against variations in image histogram content and its wide convergence range. The considerable computational expense of computing an ordered rank list is avoided here by comparing randomly chosen subsets of the DRR and reference x-ray. In this work, we show that it is possible to omit the sorting step and to compute the rank correlation coefficient of the full image content as fast as conventional merit functions. Our evaluation of a well-calibrated cadaver phantom also confirms that rank correlation-type merit functions give the most accurate results if large differences in the histogram content for the DRR and the x-ray image are present.

Figl, M.; Bloch, C.; Gendrin, C.; Weber, C.; Pawiro, S. A.; Hummel, J.; Markelj, P.; Pernuš, F.; Bergmann, H.; Birkfellner, W.

2010-10-01

296

Zonal wind generation on the gas giant planets using a 2D quasigeostrophic model  

NASA Astrophysics Data System (ADS)

It has yet to be conclusively resolved how the mean zonal winds observed on the surfaces of Jupiter and Saturn, featuring a large prograde equatorial jet and smaller jets of alternating direction at higher latitudes, are generated. While results from numerical models of thermal convection in a thin spherical shell are broadly in agreement with observations, computational limits have restricted the resolution, and thus the physical parameters, of these simulations to relatively modest regimes. It is unclear whether these results are applicable to the gas giants where the non-dimensional parameters of the system differ by 10+ orders of magnitude from numerical models. A model capable of exploring more realistic parameters would complement existing work by allowing for an investigation of how the results vary in parameter space. As well, a numerically cheap model would make it possible to study the long time scale evolution of the zonal winds. In the current work we exploit the rigid columnar flow aligned with the rotation axis observed in results from 3D models, a consequence of the quasigeostrophic force balance under rapid rotation, to develop a 2D model of the system. By simulating the flow in the equatorial plane, while integrating over the small departures from rigid 2D flow, the essential dynamics can be captured while collapsing the problem into one fewer dimensions. To develop such a model, a generalization of the standard QG framework, to account for the geometry in the polar region where the flow is bounded from below by the inner shell surface, has been developed. Numerical results from our 2D model demonstrate that such an approach can generate a banded zonal flow similar to those observed on Jupiter and Saturn.

Laycock, D.; Dumberry, M.

2011-12-01

297

Titan2D simulations of dome-collapse pyroclastic flows for crisis assessments on Montserrat  

NASA Astrophysics Data System (ADS)

The Soufriere Hills Volcano (SHV), Montserrat, has experienced numerous episodes of lava dome collapses since 1995. Collapse volumes range from small rockfalls to major dome collapses (as much as ~200 M m3). Problems arise in hazards mitigation, particularly in zoning for populated areas. Determining the likely extent of flowage deposits in various scenarios is important for hazards zonation, provision of advice by scientists, and decision making by public officials. Towards resolution of this issue we have tested the TITAN2D code, calibrated parameters for an SHV database, and using updated topography have provided flowage maps for various scenarios and volume classes from SHV, for use in hazards assessments. TITAN2D is a map plane (depth averaged) simulator of granular flow and yields mass distributions over a DEM. Two Coulomb frictional parameters (basal and internal frictions) and initial source conditions (volume, source location, and source geometry) of single or multiple pulses in a dome-collapse type event control behavior of the flow. Flow kinematics are captured, so that the dynamics of flow can be examined spatially from frame to frame, or as a movie. Our hazard maps include not only the final deposit, but also areas inundated by moving debris prior to deposition. Simulations from TITAN2D were important for analysis of crises in the period 2007-2010. They showed that any very large mass released on the north slope would be strongly partitioned by local topography, and thus it was doubtful that flows of very large size (>20 M m3) could be generated in the Belham River drainage. This partitioning effect limited runout toward populated areas. These effects were interpreted to greatly reduce the down-valley risk of ash-cloud surges.

Widiwijayanti, C.; Voight, B.; Hidayat, D.; Patra, A.; Pitman, E.

2010-12-01

298

Piezoeffect in fluorographane-like 2D supracrystals  

NASA Astrophysics Data System (ADS)

The components of the tensor of piezoelectric constants of fluorographane-like 2D supracrystals have been calculated. It has been shown that their values can be higher than those of lithium niobate. The obtained results can be used in the development of piezotransducers for the excitation and detection of terahertz elastic waves in nanoribbons and nanotubes.

Brazhe, R. A.; Kochaev, A. I.; Sovetkin, A. A.

2013-10-01

299

The dynamics of skyrmion decay in 2D magnetic films  

Microsoft Academic Search

Skyrmions are the magnetic effects in an ultrathin magnetic film with a weak anisotropy, similar to the bubble domains in thicker films. We consider the dynamics of skyrmion decay in 2D magnetic films. A simple model for taking the lattice effects into account is proposed. We show that the discreteness of the lattice leads to a slow rotation of the

Artem G. Abanov; Valery L. Pokrovsky

1998-01-01

300

Linearization of electrostatically actuated surface micromachined 2-D optical scanner  

Microsoft Academic Search

This paper presents an effective method of linearizing the electrostatic transfer characteristics of micromachined two-dimensional (2-D) scanners. The orthogonal scan angles of surface micromachined polysilicon scanner are controlled by using quadrant electrodes for electrostatic actuation. By using a pair of differential voltages over a bias voltage, we could improve the distortion of projected images from 72% to only 13%. A

Hiroshi Toshiyoshi; Wibool Piyawattanametha; Cheng-Ta Chan; Ming C. Wu

2001-01-01

301

RADMC: A 2-D Continuum Radiative Transfer Tool  

NASA Astrophysics Data System (ADS)

RADMC is a 2-D Monte-Carlo code for dust continuum radiative transfer circumstellar disks and envelopes. It is based on the method of Bjorkman & Wood (ApJ 2001, 554, 615), but with several modifications to produce smoother results with fewer photon packages.

Dullemond, C. P.

2011-08-01

302

Validation and testing of the VAM2D computer code  

SciTech Connect

This document describes two modeling studies conducted by HydroGeoLogic, Inc. for the US NRC under contract no. NRC-04089-090, entitled, Validation and Testing of the VAM2D Computer Code.'' VAM2D is a two-dimensional, variably saturated flow and transport code, with applications for performance assessment of nuclear waste disposal. The computer code itself is documented in a separate NUREG document (NUREG/CR-5352, 1989). The studies presented in this report involve application of the VAM2D code to two diverse subsurface modeling problems. The first one involves modeling of infiltration and redistribution of water and solutes in an initially dry, heterogeneous field soil. This application involves detailed modeling over a relatively short, 9-month time period. The second problem pertains to the application of VAM2D to the modeling of a waste disposal facility in a fractured clay, over much larger space and time scales and with particular emphasis on the applicability and reliability of using equivalent porous medium approach for simulating flow and transport in fractured geologic media. Reflecting the separate and distinct nature of the two problems studied, this report is organized in two separate parts. 61 refs., 31 figs., 9 tabs.

Kool, J.B.; Wu, Y.S. (HydroGeoLogic, Inc., Herndon, VA (United States))

1991-10-01

303

Graphene as a platform to study 2D electronic transitions  

Microsoft Academic Search

The easily accessible 2D electron gas in graphene provides an ideal platform on which to tune, via application of an electrostatic gate, the coupling between electronically ordered dopants deposited on its surface. To demonstrate this concept, we have measured arrays of superconducting clusters deposited on Graphene capable to induce via the proximity effect a gate-tunable superconducting transition. Using a simple

Vincent Bouchiat; Brian Kessler; Caglar Girit; Alex Zettl

2010-01-01

304

2D Laser Velocimetry Near Helicopter Blades in DNW (NLR)  

Microsoft Academic Search

Tests achieved at DNW (wind- tunnel of NLR) on an helicopter in forward flight conditions had two main purposes: on the one hand to record the components of the velocity vector in a 2D vertical frame around the blade, and on the other hand to simultaneously measure the position of the 2 m long blade which is rotating at a

A. Boutier; J. Lefevre; D. Soulevant; F. Dunand

1993-01-01

305

Nuclear Regulatory Legislation, 109th Congress, 2d Session.  

National Technical Information Service (NTIS)

This compilation of statutes and materials pertaining to nuclear regulatory legislation through the 109th Congress, 2d Session, has been prepared by the Office of the General Counsel, U.S. Nuclear Regulatory Commission, with the assistance of staff, for u...

2006-01-01

306

On the sensitivity of the 2D electromagnetic invisibility cloak  

NASA Astrophysics Data System (ADS)

A computational study of the sensitivity of the two dimensional (2D) electromagnetic invisibility cloaks is performed with the finite element method. A circular metallic object is covered with the cloak and the effects of absorption, gain and disorder are examined. Also the effect of covering the cloak with a thin dielectric layer is studied.

Kaproulias, S.; Sigalas, M. M.

2012-10-01

307

Protein Folding in 3-d and 2-d  

NSDL National Science Digital Library

A workshop on protein folding. PowerPoint presentation of the major issues in protein folding. Demonstration of 3-d protein structure by looking at the structure of lysozyme and searching for ionic bonds between side chains. 2-d simulation of protein folding called the "Protein Investigator" which allows the user to enter amino acid sequences which are then folded in 2 dimensions.

Brian White (University of Massachusetts;)

2006-06-18

308

Time-dependent backgrounds of 2D string theory  

Microsoft Academic Search

We study possible backgrounds of 2D string theory using its equivalence with a system of fermions in upside-down harmonic potential. Each background corresponds to a certain profile of the Fermi sea, which can be considered as a deformation of the hyperbolic profile characterizing the linear dilaton background. Such a perturbation is generated by a set of commuting flows, which form

Sergei Yu. Alexandrov; Vladimir A. Kazakov; Ivan K. Kostov

2002-01-01

309

QSAR models for P450 (2D6) substrate activity.  

PubMed

Human Cytochrome P450 (CYP) is a large group of enzymes that possess an essential function in metabolising different exogenous and endogenous compounds. Humans have more than 50 different genes encoding CYP enzymes, among these a gene encoding for the CYP isoenzyme 2D6, a CYP able to metabolise drugs and other chemicals. A training set of 747 chemicals primarily based on in vivo human data for the CYP isoenzyme 2D6 was collected from the literature. QSAR models focusing on substrate/non-substrate activity were constructed by the use of MultiCASE, Leadscope and MDL quantitative structure-activity relationship (QSAR) modelling systems. They cross validated (leave-groups-out) with concordances of 71%, 81% and 82%, respectively. Discrete organic European Inventory of Existing Commercial Chemical Substances (EINECS) chemicals were screened to predict an approximate percentage of CYP 2D6 substrates. These chemicals are potentially present in the environment. The biological importance of the CYP 2D6 and the use of the software mentioned above were discussed. PMID:19544194

Ringsted, T; Nikolov, N; Jensen, G E; Wedebye, E B; Niemelä, J

2009-01-01

310

Polarization dependence of Raman 2D band in bilayer graphene  

NASA Astrophysics Data System (ADS)

The Raman intensity of the double-resonance 2D band in sigle-layer graphene has a strong polarization dependence(Yoon et al. Nano Lett.). The intensity is maximum when the excitation and detection polarization are parallel and minimum when they are orthogonal, whereas that of G band is isotropic. This strong polariztion dependence is the consequence of inhomogeneous optical absorption and emission mediated by electron-phonon interactions. Here, the polarization dependence of the Raman 2D band in bilayer graphene. The 2D band of bilayer graphene can be decomposed to 4 Lorentzian peaks corresponding to different scattering process involving 2 conduction and 2 valence bands. The 2D band in bialyer graphene shows a similar polarization dependence as that of single layer. Futhermore, the excitation energy dependence was investigated by using 4 different excitation laser wavelenghths. The polarization ratio of each of the 4 Lorentizan peaks seems to reflect the features of the electronic band structure of bilayer graphene in the energy range of the excitation laser.

Lee, Jae-Ung; Mbaye Seck, Ngor; Yoon, Duhee; Cheong, Hyeonsik

2013-03-01

311

2D vs 3D, Implications on Spatial Memory  

Microsoft Academic Search

Since the introduction of graphical user interfaces (GUI) and two-dimensional (2D ) displays, the concept of space has entered the information technology (IT) domain. Interactions with computers were re-encoded in terms of fidelity to the interactions with real environment and consequently in terms of fitness to cognitive and spatial abilities. A further step in this direction was the creation of

Monica Tavanti; Mats Lind

2001-01-01

312

NKG2D ligands link oncogenic RAS to innate immunity  

PubMed Central

RAS is constitutively active in multiple types of tumor cells. We have recently demonstrated that H-RASV12 enhances the translation of ligands for the activating immune receptor NKG2D, hence rendering cells more susceptible to natural killer (NK) cell-mediated lysis. This effect depends on MAPK and PI3K signaling, but not on the DNA damage response.

Ho, Samantha S.W.; Gasser, Stephan

2013-01-01

313

E-2D advanced hawkeye: primary flight display  

Microsoft Academic Search

This paper is a response to the challenge of providing a large area avionics display for the E-2D AHE aircraft. The resulting display design provides a pilot with high-resolution visual information content covering an image area of almost three square feet (Active Area of Samsung display = 33.792cm x 27.0336 cm = 13.304\\

Paul W. Paolillo; Ragini Saxena; Jonathan Garruba; Sanjay Tripathi; Randy Blanchard

2006-01-01

314

Creation of a scalar potential in 2D dilaton gravity  

NASA Astrophysics Data System (ADS)

The authors investigate quantum corrections of the 2D dilaton gravity near the singularity. Their motivation comes from a s-wave reduced cosmological solution which is classically singular in the scalar fields (dilaton and moduli). As a result they find, that the singularity disappears and a dilaton/moduli potential is created.

Behrndt, K.

1994-09-01

315

2-D Imaging of Electron Temperature in Tokamak Plasmas  

SciTech Connect

By taking advantage of recent developments in millimeter wave imaging technology, an Electron Cyclotron Emission Imaging (ECEI) instrument, capable of simultaneously measuring 128 channels of localized electron temperature over a 2-D map in the poloidal plane, has been developed for the TEXTOR tokamak. Data from the new instrument, detailing the MHD activity associated with a sawtooth crash, is presented.

T. Munsat; E. Mazzucato; H. Park; C.W. Domier; M. Johnson; N.C. Luhmann Jr.; J. Wang; Z. Xia; I.G.J. Classen; A.J.H. Donne; M.J. van de Pol

2004-07-08

316

Wave Propagation in a 2-D Optical Waveguide  

Microsoft Academic Search

Abstract: In this work, we consider a wave propagation problem in a 2-D waveguide. Theproblem arises in the study of light in optical fibers. We construct a transform theory as a frameworkfor studying this problem. An explicit representation for the solution to problems involving lightsources is derived. We derive a decay rate for the non-guided part of the solution in

Fadil Santosa; Rolando Magnanini

2001-01-01

317

Wave Propagation In A 2-D Optical Waveguide  

Microsoft Academic Search

. In this work, we consider a wave propagation problem in a 2-D waveguide. Theproblem arises in the study of light in optical fibers. We construct a transform theory as a frameworkfor studying this problem. An explicit representation for the solution to problems involving lightsources is derived. We derive a decay rate for the non-guided part of the solution in

Rolando Magnanini; Fadil Santosa

1999-01-01

318

[Denoising worm artifacts of elastogram using 2-D wavelet shrinkage].  

PubMed

This paper proposes a technique to denoise the worm artifacts of elastogram using 2-D wavelet shrinkage denoising method. Firstly, strain estimate matrix including worm artifacts was decomposed to 3 levels by 2-D discrete wavelet transform with Sym8 wavelet function, and the thresholds were obtained using Birg6-Massart algorithm. Secondly, all the high frequency coefficients on different levels were quantized by using hard threshold and soft threshold function. Finally, the strain estimate matrix was reconstructed by using the 3rd layer low frequency coefficients and other layer quantized high frequency coefficients. The simulation results illustrated that the present technique could efficiently denoise the worm artifacts, enhance the elastogram performance indices, such as elastographic signal-to-noise ratio (SNRe) and elastographic contrast-to-noise ratio (CNRe), and could increase the correlation coefficient between the denoised elastogram and the ideal elastogram. In comparison with 2-D low-pass filtering, it could also obtain the higher elastographic SNRe and CNRe, and have clearer hard lesion edge. In addition, the results demonstrated that the proposed technique could suppress worm artifacts of elastograms for various applied strains. This work showed that the 2-D wavelet shrinkage denoising could efficiently denoise the worm artifacts of elastogram and enhance the performance of elastogram. PMID:21774202

Cui, Shaoguo; Liu, Dongquan

2011-06-01

319

Structure and vertical modes in finite 2D plasma crystals  

Microsoft Academic Search

The formation of finite 2D plasma crystals was numerically simulated to allow the investigation of structural symmetries for systems with various Debye lengths. For the case of increasing Debye length, a transition was discovered between a fully hexagonal structure and a structure having concentric rings along the outer edge and a hexagonal lattice in the interior. Additionally, the vertical as

K. Qiao; T. W. Hyde

2007-01-01

320

NKG2D ligands link oncogenic RAS to innate immunity.  

PubMed

RAS is constitutively active in multiple types of tumor cells. We have recently demonstrated that H-RASV12 enhances the translation of ligands for the activating immune receptor NKG2D, hence rendering cells more susceptible to natural killer (NK) cell-mediated lysis. This effect depends on MAPK and PI3K signaling, but not on the DNA damage response. PMID:23482418

Ho, Samantha S W; Gasser, Stephan

2013-01-01

321

2D-Computation of an Axial Fan with Finflo.  

National Technical Information Service (NTIS)

The flowpattern of an axial fan has been simulated with a 2D-version of a flow calculation program called FINFLO. The program which originally has been developed for external flows has been modified. The modified version can handle internal two-dimensiona...

K. Eriksson

1992-01-01

322

The 2D lid-driven cavity problem revisited  

Microsoft Academic Search

Numerical simulations of the 2D lid-driven cavity flow are performed for a wide range of Reynolds numbers. Accurate benchmark results are provided for steady solutions as well as for periodic solutions around the critical Reynolds number. Numerous comparisons with the results available in the literature are given. The first Hopf bifurcation is localized by a study of the linearized problem.

Charles-Henri Bruneau; Mazen Saad

2006-01-01

323

Efficient generation of diagonal constraints for 2-D mask compaction  

Microsoft Academic Search

We propose a new efficient constraint generation technique for 2-D mask compaction based on Branch-and-Bound Optimization (BBO). To assure separation in X and Y between rectangles in a layout, we generate the so called “diagonal” constraints in addition to the usual simple constraints in the X and Y directions. A diagonal constraint consist of two constraints, one in each dimension.

Guy Bois; Eduard Cerny

1996-01-01

324

Submillimeter-wave spectrum of CH2D+  

NASA Astrophysics Data System (ADS)

Aims: Recently a tentative identification of CH2D+ in interstellar space has been reported. To facilitate astronomical identifications, laboratory measurements of precise rest frequencies for the rotational lines of CH2D+ should be carried out. Methods: A submillimeter-wave spectrometer is used for detection of CH2D+. The CH2D+ ion is generated in an extended negative glow discharge operated at liquid nitrogen temperature. The optimum gas mixture is found to be CH4 (~3 mTorr), CD4 (~1 mTorr), and H2 (~2 mTorr) in helium buffer. Results: Four rotational lines have been detected in the frequency range of 280-890 GHz. The measured frequencies agree very well within a MHz with the predictions given by Rösslein et al. from the infrared spectra. Conclusions: Two rotational lines of this ion have been tentatively identified toward Ori IRc2. The rest frequencies obtained here should facilitate identifications and analysis of astronomical spectra.

Amano, T.

2010-06-01

325

Analyzing Nonconvex 2D and 3D Patterns  

Microsoft Academic Search

A nonconvex pattern can be analyzed by describing its concavity regions. These can be identified by computing the difference between the convex hull of the pattern and the pattern itself. A suitable approximation of the convex hull can be obtained by repeatedly filling local concavities of the pattern. Parallel and sequential algorithms are proposed, to fill concavities of 2D and

Gunilla Borgefors; Gabriella Sanniti Di Baja

1996-01-01

326

2D signature for detection and identification of drugs  

NASA Astrophysics Data System (ADS)

The method of spectral dynamics analysis (SDA-method) is used for obtaining the2D THz signature of drugs. This signature is used for the detection and identification of drugs with similar Fourier spectra by transmitted THz signal. We discuss the efficiency of SDA method for the identification problem of pure methamphetamine (MA), methylenedioxyamphetamine (MDA), 3, 4-methylenedioxymethamphetamine (MDMA) and Ketamine.

Trofimov, Vyacheslav A.; Varentsova, Svetlana A.; Shen, Jingling; Zhang, Cunlin; Zhou, Qingli; Shi, Yulei

2011-05-01

327

Refraction of surface acoustic waves through 2D phononic crystals  

NASA Astrophysics Data System (ADS)

We report on the first experimental evidence of negative refraction of surface acoustic waves, through a prism-shaped 2D phononic crystal having a solid matrix. The sample is constituted by a periodic array of air holes drilled in a Si substrate. The experiments are performed using a laser-ultrasonic technique.

Pierre, J.; Bonello, B.; Boyko, O.; Belliard, L.

2010-03-01

328

Obstacle Detection and Tracking Using Laser 2D  

Microsoft Academic Search

An obstacle detection and tracking system using a 2D laser sensor and the Kalman filter is presented. This filter is not very efficient in case of severe disturbances in the measured position of the obstacle, as for instance, when an object being tracked is behind a barrier, thus interrupting the laser beam, making it impossible to receive the sensor information

Danilo Habermann; Claudio Garcia

2010-01-01

329

Evaluation of Stereoscopic Images: Beyond 2D Quality  

Microsoft Academic Search

Perceived image quality is a standard evaluation concept for 2D imaging systems. When applied to stereoscopic 3D imaging systems, however, it does not incorporate the added value of stereoscopic depth. Higher level evaluation concepts (natural- ness and viewing experience) are proposed that are sensitive to both image quality and stereoscopic depth. A 3D Quality Model is constructed in which such

Marc Lambooij; Wijnand IJsselsteijn; Don G. Bouwhuis; Ingrid Heynderickx

2011-01-01

330

A potential based panel method for 2-D hydrofoils  

Microsoft Academic Search

A potential based panel method for the hydrodynamic analysis of 2-D hydrofoils moving beneath the free surface with constant speed without considering cavitation is described. By applying Green's theorem and the Green function method, an integral equation for the perturbation velocity potential is obtained under the potential flow theory. Dirichlet type boundary condition is used instead of Neumann type boundary

Sakir Bal

1998-01-01

331

The toroidal Hausdorff dimension of 2d Euclidean quantum gravity  

NASA Astrophysics Data System (ADS)

The lengths of shortest non-contractible loops are studied numerically in 2d Euclidean quantum gravity on a torus coupled to conformal field theories with central charge less than one. We find that the distribution of these geodesic lengths displays a scaling in agreement with a Hausdorff dimension given by the formula of Y. Watabiki.

Ambjørn, J.; Budd, T.

2013-07-01

332

Abelian Lagrangian algebraic geometry  

NASA Astrophysics Data System (ADS)

This paper begins a detailed exposition of a geometric approach to quantization, which is presented in a series of preprints ([23], [24], ...) and which combines the methods of algebraic and Lagrangian geometry. Given a prequantization U (1)-bundle L on a symplectic manifold M, we introduce an infinite-dimensional Kähler manifold \\mathscr P^{\\mathrm{hw}} of half-weighted Planck cycles. With every Kähler polarization on M we canonically associate a map \\mathscr P^{\\mathrm{hw}}\\overset{\\gamma}{\\to}H^{0}(M,L) to the space of holomorphic sections of the prequantization bundle. We show that this map has a constant Kähler angle and its "twisting" to a holomorphic map is the Borthwick-Paul-Uribe map. The simplest non-trivial illustration of all these constructions is provided by the theory of Legendrian knots in S^3.

Gorodentsev, A. L.; Tyurin, A. N.

2001-06-01

333

Geometry from Gauge Theory  

SciTech Connect

We discuss how geometrical and topological aspects of certain (1/2)-BPS type IIB geometries are captured by their dual operators in N = 4 Super Yang-Mills theory. The type IIB solutions are characterized by arbitrary droplet pictures in a plane and we consider, in particular, axially symmetric droplets. The 1-loop anomalous dimension of the dual gauge theory operators probed with single traces is described by some bosonic lattice Hamiltonians. These Hamiltonians are shown to encode the topology of the droplets. In appropriate BMN limits, the Hamiltonians spectrum reproduces the spectrum of near-BPS string excitations propagating along each of the individual edges of the droplet. We also study semiclassical regimes for the Hamiltonians. For droplets having disconnected constituents, the Hamiltonian admits different complimentary semiclassical descriptions, each one replicating the semiclassical description for closed strings extending in each of the constituents.

Correa, Diego H. [DAMTP, Centre for Mathematical Sciences, University of Cambridge Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Silva, Guillermo A. [IFLP-CCT-La Plata, CONICET and Departamento de Fisica, Universidad Nacional de La Plata CC 67, (1900) La Plata (Argentina)

2008-07-28

334

Symplectic Geometry of Entanglement  

NASA Astrophysics Data System (ADS)

We present a description of entanglement in composite quantum systems in terms of symplectic geometry. We provide a symplectic characterization of sets of equally entangled states as orbits of group actions in the space of states. In particular, using the Kostant-Sternberg theorem, we show that separable states form a unique symplectic orbit, whereas orbits of entangled states are characterized by different degrees of degeneracy of the canonical symplectic form on the complex projective space. The degree of degeneracy may be thus used as a new geometric measure of entanglement. The above statements remain true for systems with an arbitrary number of components, moreover the presented method is general and can be applied also under different additional symmetry conditions stemming, e.g., from the indistinguishability of particles. We show how to calculate the degeneracy for various multiparticle systems providing also simple criteria of separability.

Sawicki, Adam; Huckleberry, Alan; Ku?, Marek

2011-07-01

335

Studies in quantum geometry  

NASA Astrophysics Data System (ADS)

The geometric defects associated with open strings have become a mainstay in the arsenal of the string theorist. These objects are intimately tied to the properties of spacetime. D-branes have been well studied in the nineties and orientifolds are only now been thoroughly investigated. This thesis is built on two different studies. The first, done with Koenraad Schalm and Chuck Doran attempts to analyze the possible Orientifolds and their moduli, starting from Gepner models of the spacetime. The main focus was on elliptical compactifications, as this could be used as building block for more complex geometries. It is noteworthy that the orientifolds place constraints on the possible spacetime geometries, whilst also being characterized by the geometrical nature of the involutions defining them. The second study of this thesis, which was done with Frederik Denef, is on the low energy manifestations of D-branes as supergravity attractor solutions. Four dimensional N = 2 supergravity has regular, stationary, asymptotically flat BPS solutions with intrinsic angular momentum, describing bound states of separate extremal black holes with mutually nonlocal charges. Though the existence and some properties of these solutions were established some time ago, fully explicit analytic solutions were lacking thus far. In this study this gap is filled. We found that in general explicit solutions can be constructed whenever an explicit formula is known in the theory at hand for the Bekenstein-Hawking entropy of a single black hole as a function of its charges, and illustrated this with some simple examples. We also found an example of moduli-dependent black hole entropy.

Bates, Brandon D.

336

Flood hazard assessment using 1D and 2D approaches  

NASA Astrophysics Data System (ADS)

The EU flood risk Directive (Directive 2007/60/EC) prescribes risk assessment and mapping to develop flood risk management plans. Flood hazard mapping may be carried out with mathematical models able to determine flood-prone areas once realistic conditions (in terms of discharge or water levels) are imposed at the boundaries of the case study. The deterministic models are mainly based on shallow water equations expressed in their 1D or 2D formulation. The 1D approach is widely used, especially in technical studies, due to its relative simplicity, its computational efficiency and also because it requires topographical data not as expensive as the ones needed by 2D models. Even if in a great number of practical situations, such as modeling in-channel flows and not too wide floodplains, the 1D approach may provide results close to the prediction of a more sophisticated 2D model, it must be pointed out that the correct use of a 1D model in practical situations is more complex than it may seem. The main issues to be correctly modeled in a 1D approach are the definition of hydraulic structures such as bridges and buildings interacting with the flow and the treatment of the tributaries. Clearly all these aspects have to be taken into account also in the 2D modeling, but with fewer difficulties. The purpose of this paper is to show how the above cited issues can be described using a 1D or 2D unsteady flow modeling. In particular the Authors will show the devices that have to be implemented in 1D modeling to get reliable predictions of water levels and discharges comparable to the ones obtained using a 2D model. Attention will be focused on an actual river (Crati river) located in the South of Italy. This case study is quite complicated since it deals with the simulation of channeled flows, overbank flows, interactions with buildings, bridges and tributaries. Accurate techniques, intentionally developed by the Authors to take into account all these peculiarities in 1D and 2D modeling, will be presented, compared and discussed.

Petaccia, Gabriella; Costabile, Pierfranco; Macchione, Francesco; Natale, Luigi

2013-04-01

337

Complex 2D matrix model and geometrical map on the complex-Nc plane  

NASA Astrophysics Data System (ADS)

We study the parameter dependence of the internal structure of resonance states by formulating a complex two-dimensional (2D) matrix model, where the two dimensions represent two levels of resonances. We calculate a critical value of the parameter at which a "nature transition" with character exchange occurs between two resonance states, from the viewpoint of geometry on complex-parameter space. Such a critical value is useful for identifying the internal structure of resonance states with variation of the parameter in the system. We apply the model to analyze the internal structure of hadrons with variation of the color number N_c from infty to a realistic value 3. By regarding 1/N_c as the variable parameter in our model, we calculate a critical color number of the nature transition between hadronic states in terms of a quark-antiquark pair and a mesonic molecule as exotics from the geometry on the complex-N_c plane. For large-N_c effective theory, we employ the chiral Lagrangian induced by holographic QCD with a D4/D8/overline {D8} multi-D brane system in type IIA superstring theory.

Nawa, Kanabu; Ozaki, Sho; Nagahiro, Hideko; Jido, Daisuke; Hosaka, Atsushi

2013-08-01

338

Fully coupled nonlinear thermomechanical analysis including general contact in PALM2D  

SciTech Connect

Fully coupled thermomechanical analysis solves the thermal problem on the deforming geometry and incorporates thermal loads into the mechanical problem. In contrast, traditional thermal stress analysis is based on an uncoupled approach in which the thermal problem is solved on a fixed geometry, and the resulting temperatures are then used to load a mechanical problem. Thermal contact, in which heat flow paths depend on the mechanical deformations of adjacent surfaces, is a major component of many fully coupled thermomechanical analyses. This paper presents the development of a thermomechanical finite element formulation, including contact. The proposed approach accommodates arbitrarily large relative motions of contact surfaces, fully unstructured meshes, pressure-dependent contact resistance, conduction across small gaps, and approximate models for convection and radiation. The theory described herein has been implemented in the Lawrence Livermore National Laboratory public code PALM2D and has been used to solve a diverse set of thermomechanical problems. Examples illustrating the performance of this code on large deformation thermomechanical problems are presented and discussed.

Engelmann, B.E.; Whirley, R.G.

1993-10-07

339

Infrared pushbroom camera breadboard using off-the-shelf 2D array of detector  

NASA Astrophysics Data System (ADS)

Performances for nowadays optronic systems require focal plane arrays (FPA) with an increasing number of detectors. The `push- broom' technic is well adapted to earth observation in the visible range with the availability of long linear CCD'S offering thousands of pixels. In the infrared, line scan systems are preferred at the present time because technological difficulties have to be overcome in order to get long linear arrays. Among the most important, are: (1) Difficulties to have a large cold focal plane with a temperature uniformity of a few degrees. (2) Difficulties to get good detection material over large surface. Mechanical or optical butting technology can be used there but with dead pixels and/or side effects. (3) Very low cold shield efficiency due to the geometry of the long linear array. (4) Very high development costs. MATRA DEFENSE UAO has made the design of a new infrared FPA concept which has the advantage to overcome all drawbacks listed previously (patented design). The idea consists to transform the pixel arrangement geometry of a 2D array which is available off the shelf into a long linear FPA using a coherent infrared fiber optic reformatter. In order to demonstrate the feasibility of this new FPA concept, a camera breadboard has been built. This task has been supported by the French MOD (STTE). This paper describes this breadboard and gives main technical performances.

Bernier, Joel; Plainchamp, Patrick; Bardon, Dominique

1994-09-01

340

A 2D flow visualization user study using explicit flow synthesis and implicit task design.  

PubMed

This paper presents a 2D flow visualization user study that we conducted using new methodologies to increase the objectiveness. We evaluated grid-based variable-size arrows, evenly spaced streamlines, and line integral convolution (LIC) variants (basic, oriented, and enhanced versions) coupled with a colorwheel and/or rainbow color map, which are representative of many geometry-based and texture-based techniques. To reduce data-related bias, template-based explicit flow synthesis was used to create a wide variety of symmetric flows with similar topological complexity. To suppress task-related bias, pattern-based implicit task design was employed, addressing critical point recognition, critical point classification, and symmetric pattern categorization. In addition, variable-duration and fixed-duration measurement schemes were utilized for lightweight precision-critical and heavyweight judgment intensive flow analysis tasks, respectively, to record visualization effectiveness. We eliminated outliers and used the Ryan REGWQ post-hoc homogeneous subset tests in statistical analysis to obtain reliable findings. Our study shows that a texture-based dense representation with accentuated flow streaks, such as enhanced LIC, enables intuitive perception of the flow, while a geometry-based integral representation with uniform density control, such as evenly spaced streamlines, may exploit visual interpolation to facilitate mental reconstruction of the flow. It is also shown that inappropriate color mapping (e.g., colorwheel) may add distractions to a flow representation. PMID:21690646

Liu, Zhanping; Cai, Shangshu; Swan, J Edward; Moorhead, Robert J; Martin, Joel P; Jankun-Kelly, T J

2012-05-01

341

Cloud geometry effects on atmospheric solar absorption  

SciTech Connect

A 3D broadband solar radiative transfer scheme is formulated by integrating a Monte Carlo photon transport algorithm with the Fu-Liou radiation model. It is applied to fields of tropical mesoscale convective clouds and subtropical marine boundary layer clouds that were generated by a 2D cloud-resolving model. The effects of cloud geometry on the radiative energy budget are examined by comparing the full-resolution Monte Carlo results with those from the independent column approximation (ICA) that applies the plane-parallel radiation model to each column. For the tropical convective cloud system, it is found that cloud geometry effects always enhance atmospheric solar absorption regardless of solar zenith angle. In a large horizontal domain (512 km), differences in domain-averaged atmospheric absorption between the Monte Carlo and the ICA are less than 4 W m{sup {minus}2} in the daytime. However, for a smaller domain (e.g., 75 km) containing a cluster of deep convective towers, domain-averaged absorption can be enhanced by more than 20 W m{sup {minus}2}. For a subtropical marine boundary layer cloud system during the stratus-to-cumulus transition, calculations show that the ICA works very well for domain-averaged fluxes of the stratocumulus cloud fields even for a very small domain (4.8 km). For the trade cumulus cloud field, the effects of cloud sides and horizontal transport of photons become more significant. Calculations have also been made for both cloud systems including black carbon aerosol and a water vapor continuum. It is found that cloud geometry produces no discernible effects on the absorption enhancement due to the black carbon aerosol and water vapor continuum. The current study indicates that the atmospheric absorption enhancement due to cloud-related 3D photon transport is small. This enhancement could not explain the excess absorption suggested by recent studies.

Fu, Q.; Cribb, M.C.; Barker, H.W.; Krueger, S.K.; Grossman, A.

2000-04-15

342

Direct comparison of 2D PIV and stereoscopic PIV measurements  

NASA Astrophysics Data System (ADS)

A stereoscopic particle image velocimetry (PIV) measurement system based on the translation configuration was developed and applied to the flow behind a forward-swept axial-fan with five blades in a water tank. The 3D calibration procedure was employed to compensate the distortion and refraction of particle images. The perspective error caused by the out-of-plane motion was estimated by direct comparison of the 2D PIV and stereoscopic PIV (SPIV) results. The SPIV and 2D PIV comparison was carried out for the particle images captured simultaneously. The difference of mean velocity data measured by 2D PIV and SPIV techniques is nearly proportional to the mean out-of-plane velocity component. The difference appears to be relatively large in the region near the fan blade having higher out-of-plane motion. The perspective error estimated from the calibration data and mean out-of-plane velocity data agrees with the mean velocity difference between the 2D PIV and SPIV results. The turbulence intensity measured by the 2D PIV method is overestimated in comparison to that of the SPIV method due to the projected velocity fluctuations of the out-of-plane velocity component. The turbulent fluctuations caused by the out-of-plane velocity component were estimated by multiplication of the incident angle obtained in the calibration procedure and out-of-plane velocity fluctuations. The estimated perspective fluctuation of the out-of-plane velocity component was compared with the difference measured by the two methods. In SPIV measurements of turbulent statistics, therefore, the ratio of out-of-plane to in-plane RMS error determined from the system set-up should be considered in order to obtain reliable results.

Yoon, Jong-Hwan; Lee, Sang-Joon

2002-10-01

343

Learning Geometry in Georgian England  

NSDL National Science Digital Library

How did people learn geometry in Georgian England? It was different than in our own time, to be sure. This feature from Loci, the online publication of the MAA Mathematical Sciences Digital Library offers a bit of detail on the matter, courtesy of the geometry copybook of a boy named Thomas Porcher. This particular feature was written by Benjamin Wardhaugh from the University of Oxford. In the six-part feature, Wardhaugh looks into why such a boy would learn geometry and also what the existing texts were at the time. The article contains sections like "Geometry and Measuring" and "Geometry and Practical Geometry." It's a fascinating study, and one that will be intriguing to those with a penchant for the history of mathematics and pedagogy.

Wardhaugh, Benjamin, 1979-; Porcher, Thomas

2012-09-21

344

2-D analytic model for inductively coupled plasma sources. Part 2: Effects of 2-D coupled damping and their applications  

Microsoft Academic Search

In Part 1, the authors developed the electromagnetic model and analyzed the plasma kinetic behavior for the recently developed inductively coupled plasma sources (ICPS). The analytic forms demonstrated that the induced RF wave in ICPS is primarily dampened by a collisionless dissipation mechanism. In this paper, the 2-D coupled damping effect is further discussed. A criterion is given to describe

C. H. J. Wu; F. Dai

1995-01-01

345

Cytochrome P450-2D6 Screening Among Elderly Using Antidepressants (CYSCE)  

ClinicalTrials.gov

Depression; Depressive Disorder; Poor Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Intermediate Metabolizer Due to Cytochrome P450 CYP2D6 Variant; Ultrarapid Metabolizer Due to Cytochrome P450 CYP2D6 Variant

2013-09-16

346

DRC2: A code with specialized applications for coupling localized Monte Carlo adjoint calculations with fluences from two-dimensional R-Z discrete ordinates air-over-ground calculations  

SciTech Connect

The DRC2 code, which couples MASH or MASHX adjoint leakages with DORT 2-D discrete ordinates forward directional fluences, is described. The forward fluences are allowed to vary both axially and radially over the coupling surface, as opposed to the strictly axial variation allowed by the predecessor DRC code. Input instructions are presented along with descriptions and results from several sample problems. Results from the sample problems are used to compare DRC2 with DRC, DRC2 with DORT, and DRC2 with itself for the case of x-y dependence versus no x-y dependence of the forward fluence. The test problems demonstrate that for small systems DRC and DRC2 give essentially the same results. Some significant differences are noted for larger systems. Additionally, DRC2 results with no x-y dependence of the forward directional fluences are practically the same as those calculated by DRC.

Slater, C.O.

1992-01-01

347

Comparison of aortic root dimensions and geometries before and after transcatheter aortic valve implantation by 2- and 3-dimensional transesophageal echocardiography and multislice computed tomography  

Microsoft Academic Search

BACKGROUND: 3D transesophageal echocardiography (TEE) may provide more accurate aortic annular and left ventricular outflow tract (LVOT) dimensions and geometries compared with 2D TEE. We assessed agreements between 2D and 3D TEE measurements with multislice computed tomography (MSCT) and changes in annular\\/LVOT areas and geometries after transcatheter aortic valve implantations (TAVI). METHODS AND RESULTS: Two-dimensional circular (pixr(2)), 3D circular, and

A. C. T. Ng; V. Delgado; F. van der Kley; M. Shanks; N. R. L. van de Veire; M. Bertini; G. Nucifora; R. J. van Bommel; L. F. Tops; A. de Weger; G. Tavilla; A. de Roos; L. J. Kroft; D. Y. Leung; J. Schuijf; M. J. Schalij; J. J. Bax

2010-01-01

348

Titan 2D: Understanding Titan’s Seasonal Atmospheric Cycles  

NASA Astrophysics Data System (ADS)

In this study, we present results from a novel two-dimensional (2D) model that simulates the physics and chemistry of Titan’s atmosphere. Despite being an icy moon of Saturn, Titan is the only Solar System object aside from Earth that is sheathed by a thick nitrogen-dominated atmosphere. This vulnerable gaseous envelope—an embodiment of a delicate coupling between photochemistry, radiation, and dynamics—is Nature’s laboratory for the synthesis of complex organic molecules. Titan’s large obliquity generates pronounced seasonal cycles in its atmosphere, and the Cassini spacecraft has been observing these variations since 2004. In particular, Cassini measurements show that the latitudinal distribution of Titan’s rich mélange of hydrocarbon species follows seasonal patterns. The mixing ratios of hydrocarbons increase with latitude towards the winter pole, suggesting a pole-to-pole circulation that reverses after equinox. Using a one-dimensional photochemical model of Titan’s atmosphere, we show that photochemistry alone cannot produce the observed meridional hydrocarbon distribution. This necessitates the employment of a 2D chemistry-transport model that includes meridional circulation as well as diffusive processes and photochemistry. Of additional concern, no previous 2D model of Titan extends beyond 500 km altitude—a critical limitation since the peak of methane photolysis is at 800 km. Our 2D model is the first to include Titan’s stratosphere, mesosphere, and thermosphere. The meridional circulation in our 2D model is derived from the outputs of two general circulation models (GCMs): the TitanWRF GCM (Newman et al. 2011) covering the troposphere, stratosphere, and lower mesosphere, and a thermosphere general circulation model (TGCM) covering the remainder of the atmosphere through the thermosphere (Müller-Wodarg et al. 2003; 2008). This presentation will focus on the utilization of these advances applied to the 2D Caltech/JPL KINETICS model to understand the seasonal and meridional distribution of hydrocarbons as well as other atmospheric cycles on Titan.

Wong, Michael; Zhang, X.; Li, C.; Hu, R.; Shia, R.; Newman, C.; Müller-Wodarg, I.; Yung, Y.

2013-10-01

349

Reformation of Perpendicular Shocks: 1-D VS 2-D Simulations  

NASA Astrophysics Data System (ADS)

Perpendicular shocks simulated using 1-D both hybrid and PIC codes are strongly non-stationary (exhibit self-reformation process) for a wide range of upstream parameters (low proton beta and/or high Mach numbers). We present new 2-D simulation results using both hybrid and PIC codes of the perpendicular shocks and compare them with the corresponding 1-D simulations. One striking feature observed in the simulations is that shocks which are self-reforming in 1-D reveal to be almost stationary in 2-D and their foot region is dominated by whistler waves propagating obliquely with respect to the shock normal and to the magnetic field. These simulations indicate that the emitted whistler waves inhibit the self-reformation process.

Hellinger, P.; Travnicek, P.; Lembege, B.; Savoini, P.

2007-05-01

350

Implementation of 2-D DCT based on FPGA  

NASA Astrophysics Data System (ADS)

Discrete Cosine Transform (DCT) plays an important role in the image and video compression, and it has been widely used in JPEG, MPEG, H.26x. DCT being implemented by hardware is crucial to improve the speed of image compression. This paper presents a method that 2-D DCT is implemented by FPGA, which is based on the algorithm of row-column decomposition, and the parallel structure is used to achieve high throughput. The design is achieved by top-down design methodology and described with Verilog HDL in RTL level. The hardware of 2-D DCT is implemented by the FPGA EP2C35F672C8 made by ALTERA. The experiment results show that the delay time is as low as 15 ns, and the clock frequency as high as 138.35 MHz, which can satisfy the requirements of the real-time video image compression.

Guo, Bao-Zeng; Niu, Li; Liu, Zhi-Ming

2010-08-01

351

Micro-structural Fluctuations in 2D Dusty Plasma Liquids  

NASA Astrophysics Data System (ADS)

We address structural fluctuations in a cold 2D dusty plasma liquid which is self-organized through the strong Coulomb coupling of the negatively charged micro-meter sized dust particles suspending in weakly ionized discharges. The 2D liquids consist of triangular type ordered domains surrounded by defect clusters, which can be reorganized through avalanche type hopping under the interplay of strong Coulomb coupling and thermal fluctuations. The spatio-temporal evolutions of the local bond-orientational order are directly tracked through digital optical microscopy. The power law scaling of the temporal persistence length of fluctuations is obtained for the cold liquid. The measurement of the conditional probability of the persistence lengths of the successive fluctuating cycles suggests certain types of the persistence length combinations are more preferred. The memory of persistence lasts a few fluctuating cycles.

I, Lin; Huang, Yu-Hsuan; Teng, Lee-Wen

2007-07-01

352

Development of 2D Ionization Chamber for Particle Therapy  

NASA Astrophysics Data System (ADS)

Recently rapid growth in particle therapy has imposed new detector developments for quality assurance (QA) purposes. Relatively high dose deposition from proton or carbon ion beam requires stringent performance from detectors. Cyclotron, synchrotron, or future laser driven accelerators represent DC and pulse sources which need different timing designs in electronics. Dose and position measurements of particle beams can serve clinical, beam diagnosis and QA purposes. We categorize the parameters of detectors - electronics, DAQ, and simulation--to serve for later optimizations. Gaseous detector is preferred because of its radiation hardness, and operation at ionization mode provides stable condition. We present our progresses in 2D ionization chamber development. Basic studies are carried out on 1D ionization chamber, which consists of 16 6-mm-wide strips. Results of measuring electron and proton beams are compared with MC simulations. 2D array ionization chamber design is optimized and based on 1D prototype measurements.

Ho, Chi-Li

2010-11-01

353

Spinfoam 2D quantum gravity and discrete bundles  

NASA Astrophysics Data System (ADS)

In four dimensions (4D), general relativity (GR) can be formulated as a constrained BF theory; we show that the same is true in 2D. We describe a spinfoam quantization of this constrained BF formulation of 2D Riemannian GR, obtained using the Barrett Crane technique of imposing the constraint as a restriction on the representations summed over. We obtain the expected partition function, thus providing support for the viability of the technique. The result requires the nontrivial topology of the bundle where the gravitational connection is defined to be taken into account. For this purpose, we study the definition of a principal bundle over a simplicial base space. The model also sheds light on several other features of spinfoam quantum gravity: the reality of the partition function, the geometrical interpretation of the Newton constant and the issue of possible finiteness of the partition function of quantum GR.

Oriti, Daniele; Rovelli, Carlo; Speziale, Simone

2005-01-01

354

A Better 2-D Mechanical Energy Conservation Experiment  

NASA Astrophysics Data System (ADS)

A variety of simple classical mechanics energy conservation experiments are used in teaching laboratories. Typical one-dimensional (1-D) setups may involve falling balls or oscillating springs. Many of these can be quite satisfying in that students can confirm--within a few percent--that mechanical energy is conserved. Students generally have little trouble identifying discrepancies such as the loss of a few percent of the gravitational potential energy due to air friction encountered by a falling ball. Two-dimensional (2-D) systems can require more sophisticated analysis for higher level laboratories, but such systems often incorporate complicating components that can make the exercise academically incomplete and experimentally less accurate. The following describes a simple 2-D energy conservation experiment based on the popular ``Newton's Cradle'' toy that allows students to account for nearly all of the mechanical energy in the system in an academically complete analysis.

Paesler, Michael

2012-02-01

355

Expression of Four Rat CYP2D Isoforms in Saccharomyces cerevisiaeand Their Catalytic Specificity  

Microsoft Academic Search

We cloned four cDNAs belonging to the CYP2D subfamily to express these enzymes in yeast cells and to compare their catalytic activities simultaneously. Three are believed to be alleles of CYP2D1, 2D2, and 2D3, respectively, based on high nucleotide sequence similarity, while CYP2D4 had both sequences of CYP2D4 and CYP2D18. Expression plasmids carrying CYP2D cDNAs were transformed intoSaccharomyces cerevisiae.Typical P450

Jie Wan; Susumu Imaoka; Toshio Chow; Toyoko Hiroi; Yoshiyasu Yabusaki; Yoshihiko Funae

1997-01-01

356

Texture Segmentation using 2-D Gabor Elementary Functions  

Microsoft Academic Search

Many texture-segmentation schemes use an elaborate bank of filters to decompose a textured image into a joint space\\/spatial-frequency representation. Although these schemes show promise, and although some analytical work has been done, the relationship between texture differences and the filter configurations required to distinguish them remain largely unknown. This paper examines the issue of designing individual filters. Using a 2-D

Dennis F. Dunn; William E. Higgins; Joseph Wakeley

1994-01-01

357

On the Expected Size of the 2D Visibility Complex  

Microsoft Academic Search

Abstract We study the expected size of the 2D visibility complex,of randomly,distributed objects in the plane. We prove that the asymptotic expected number,of free bitangents (which correspond to 0-faces of the visibility complex) among unit discs (or polygons,of bounded,aspect ratio and similar size) is linear and exhibit bounds,in terms of the density of the objects. We also make,an experimental assessment

Hazel Everett; Sylvain Lazard; Sylvain Petitjean; Linqiao Zhang

2007-01-01

358

Predicting 3D People from 2D Pictures  

Microsoft Academic Search

We propose a hierarchical process for inferring the 3D pose of a per- son from monocular images. First we infer a learned view-based 2D body model from a single image using non-parametric belief propagation. This approach integrates information from bottom-up body-part proposal processes and deals with self-occlusion to compute distributions over limb poses. Then, we exploit a learned Mixture of

Leonid Sigal; Michael J. Black

2006-01-01

359

2d electronic gas properties of epitaxial graphene  

Microsoft Academic Search

We present transport measurement on multi-layered epitaxial graphene grown on SiC. The films, a few to a few dozen layers thick, can be lithographically patterned and show remarkable 2d electron gas properties. In high mobility samples (up to 10^4 cm^2\\/Vs) perpendicular magnetoresistance measurements indicate micrometer long electronic phase coherence lengths at 4K, comparable to the sample size. Pronounced Shubnikov --de

Claire Berger; Cecile Naud; Zhimin Song; Xuebin Li; Walt de Heer

2006-01-01

360

CBEAM. 2-D: a two-dimensional beam field code  

SciTech Connect

CBEAM.2-D is a two-dimensional solution of Maxwell's equations for the case of an electron beam propagating through an air medium. Solutions are performed in the beam-retarded time frame. Conductivity is calculated self-consistently with field equations, allowing sophisticated dependence of plasma parameters to be handled. A unique feature of the code is that it is implemented on an IBM PC microcomputer in the BASIC language. Consequently, it should be available to a wide audience.

Dreyer, K.A.

1985-05-01

361

Stereoscopic highlighting: 2D graph visualization on stereo displays.  

PubMed

In this paper we present a new technique and prototype graph visualization system, stereoscopic highlighting, to help answer accessibility and adjacency queries when interacting with a node-link diagram. Our technique utilizes stereoscopic depth to highlight regions of interest in a 2D graph by projecting these parts onto a plane closer to the viewpoint of the user. This technique aims to isolate and magnify specific portions of the graph that need to be explored in detail without resorting to other highlighting techniques like color or motion, which can then be reserved to encode other data attributes. This mechanism of stereoscopic highlighting also enables focus+context views by juxtaposing a detailed image of a region of interest with the overall graph, which is visualized at a further depth with correspondingly less detail. In order to validate our technique, we ran a controlled experiment with 16 subjects comparing static visual highlighting to stereoscopic highlighting on 2D and 3D graph layouts for a range of tasks. Our results show that while for most tasks the difference in performance between stereoscopic highlighting alone and static visual highlighting is not statistically significant, users performed better when both highlighting methods were used concurrently. In more complicated tasks, 3D layout with static visual highlighting outperformed 2D layouts with a single highlighting method. However, it did not outperform the 2D layout utilizing both highlighting techniques simultaneously. Based on these results, we conclude that stereoscopic highlighting is a promising technique that can significantly enhance graph visualizations for certain use cases. PMID:22034353

Alper, Basak; Höllerer, Tobias; Kuchera-Morin, JoAnn; Forbes, Angus

2011-12-01

362

Possible Ordered States in the 2D Extended Hubbard Model  

Microsoft Academic Search

Possible ordered states in the 2D extended Hubbard model with on-site (U>0) and nearest-neighbor (V) interaction are examined near half filling, with emphasis on the effect of finite V.First, the phase diagram at absolute zero is determined in the mean field approximation. For V<0, a state wheredx2-y2-wave superconductivity (dSC),commensurate spin-density-wave (SDW) andpi-triplet pair coexist is seen to be stabilized.Here, the

Masakazu Murakami

2000-01-01

363

On the complexity of 2D discrete fixed point problem  

Microsoft Academic Search

We study a computational complexity version of the 2D Sperner problem, which states that any three coloring of vertices of a triangulated triangle, satisfying some boundary conditions, will have a trichromatic triangle. In introducing a complexity class PPAD, Papadimitriou [C.H. Papadimitriou, On graph-theoretic lemmata and complexity classes, in: Proceedings of the 31st Annual Symposium on Foundations of Computer Science, 1990,

Xi Chen; Xiaotie Deng

2009-01-01

364

Electromagnetic velocity inversion using 2-D Maxwell's equations  

Microsoft Academic Search

The authors adapt the wave-equation traveltime inversion (WT) method to the reconstruction of the dielectric distribution from crosswell radar traveltime data. The data misfit gradient is computed using finite-difference solutions to the 2-D Maxwell`s equations. An advantage of the wave-equation method over ray-tracing radar tomography is that it accounts for scattering and diffusion effects and works well in both resistive

Wenying Cai; F. Qin; G. T. Schuster

1996-01-01

365

DSD comparison between Parsivel and 2D video disdrometers  

Microsoft Academic Search

A low profile 2D video disdrometer (2DVD_lp) was installed in northern Alabama, USA, at a well-instrumented site in June 2007. The instrument has been precisely calibrated to measure size, fall velocity, and for fully melted hydrometeors, the orientation and shape of all particles falling through its 10 cm by 10 cm sensor area. Although meant originally for drop shape studies,

Merhala Thurai; Walter Petersen; Ali Tokay; Christopher Schultz; Patrick Gatlin

2010-01-01

366

A coaxial 2D-periodic perforated directional coupler  

NASA Astrophysics Data System (ADS)

We propose to couple two coaxial waveguides by 2D periodic perforation in the common wall in order to ensure selective coupling between two waves propagating in these waveguides. In the experiment at a frequency of 10 GHz, the H 01 mode of the internal waveguide was converted to the rotating H 51 mode of the external waveguide with a power loss of several percent.

Danilov, Yu. Yu.; Petelin, M. I.; Tantawi, S.

2012-04-01

367

On the transition between 2D and 3D dunes  

Microsoft Academic Search

Sediment transport in sand-bedded alluvial channels is strongly conditioned by bedforms, the planimetric morphology of which can be either two- or three- dimensional. Experiments were undertaken to examine the processes that transform the bed configuration from two-dimensional (2D) dunes to three- dimensional (3D) dunes. A narrowly graded, 500 lm size sand was subjected to a 0Æ15 m deep, non-varying mean

JEREMY G. VENDITTI; MICHAEL CHURCH; SEAN J. BENNETT

2005-01-01

368

Immunobiology of Human NKG2D and Its Ligands  

Microsoft Academic Search

The NKG2D-DAP10 receptor complex activates natural killer (NK) cells and costimulates effector T cell subsets upon engagement\\u000a of ligands that can be conditionally expressed under physiologically harmful conditions such as microbial infections and malignancies.\\u000a These characteristics have given rise to the widely embraced concept of immunorecognition of “induced or damaged self,” complementing\\u000a the “missing self” paradigm that is represented by

S. González; V. Groh; T. Spies

369

Backgrounds of 2D string theory from matrix model  

Microsoft Academic Search

In the Matrix Quantum Mechanical formulation of 2D string theory it is\\u000apossible to introduce arbitrary tachyonic perturbations. In the case when the\\u000atachyonic momenta form a lattice, the theory is known to be integrable and,\\u000atherefore, it can be used to describe the corresponding string theory. We study\\u000athe backgrounds of string theory obtained from these matrix model solutions.

Sergei Alexandrov; Ecole Normale Superieure; V. A. Fock

2003-01-01

370

PISCES-MC: a multiwindow, multimethod 2-D device simulator  

Microsoft Academic Search

A multiwindow, multimethod device analysis algorithm that combines the advantages of efficient drift-diffusion simulators and accurate physical models using Monte Carlo methods is described. The PISCES 2-D device analysis program is used whenever the drift-diffusion model is valid. In situations where the drift-diffusion model breaks down, a window is opened in the part of the device where the hot-carrier effects

D. Y. Cheng; Chang G. Hwang; Robert W. Dutton

1988-01-01

371

MULTIPAC - MULTIPACTING SIMULATION PACKAGE WITH 2D FEM  

Microsoft Academic Search

MultiPac is a multipacting simulation package for analyzing electron multipacting in axisymmetric RF structures with TM_0nl mode, such as RF cavities, coaxial input couplers and ceramic windows. The package includes a graphical MATLAB user interface and a 2D finite element electromagnetic field solver with third order basis functions. The multipacting simulations are carried out by combining the standard electron trajectory

P. Ylä-Oijala

372

Preparation of Plant Protein Samples for 2-D PAGE  

Microsoft Academic Search

\\u000a A critical step in the application of O’Farrell’s (1) two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) in plant biology research is the preparation of plant protein\\u000a samples free of artefactual protein modifications and without adversely affecting gel resolving power and reproducibility.\\u000a However, it is important to note that many problems could be encountered in this step. A large part of the

David W. M. Leung

373

An improved multicrystal 2-D BGO detector for PET  

Microsoft Academic Search

The authors evaluate and compare two 2-D array detectors for positron emission tomography (PET). Both consisted of an 8×8 array of small BGO crystals coupled to a 2×2 array of photomultiplier tubes. The depth of the crystals was 3 cm in one detector and 2 cm in the other. The 2-cm detector is superior in terms of material costs, in

J. G. Rogers; A. J. Taylor; M. F. Rahimi; R. Nutt; M. Andreaco; C. W. Williams

1992-01-01

374

GPGPU simulations of 2D lattice neutral models in ecology  

NASA Astrophysics Data System (ADS)

2D lattice neutral models in ecology are studied using general-purpose computing on graphic processing units (GPGPU). Processing times of GPGPU and CPU simulations are compared for various system sizes and it is found out that the larger the system size, the faster the GPGPU version, and the efficiency of GPGPU is maximally 263 times higher. Ecological significance of the GPGPU simulations and the lattice neutral model is also reported.

Oura, Takeshi; Tokita, Kei

2013-08-01

375

Dynamic 2D IR spectroscopy of poly(?-caprolactone)  

Microsoft Academic Search

Dynamic two-dimensional infrared (2D IR) spectroscopy evolved from the analysis of orthogonal spectral data sets generated by a rheo-optical dynamic IR linear dichroism (DIRLD) measurement of polymer films undergoing a small-amplitude oscillatory deformation. DIRLD spectroscopy has provided new insight into polymer deformation mechanisms and how they change as a function of temperature and deformation frequency. In general, we observe that

C. Marcott; A. E. Dowrey; G. M. Story; I. Noda

2000-01-01

376

Dynamic 2D IR spectroscopy of poly(&Vegr;-caprolactone)  

Microsoft Academic Search

Dynamic two-dimensional infrared (2D IR) spectroscopy evolved from the analysis of orthogonal spectral data sets generated by a rheo-optical dynamic IR linear dichroism (DIRLD) measurement of polymer films undergoing a small-amplitude oscillatory deformation. DIRLD spectroscopy has provided new insight into polymer deformation mechanisms and how they change as a function of temperature and deformation frequency. In general, we observe that

C. Marcott; A. E. Dowrey; G. M. Story; I. Noda

2000-01-01

377

Development of 2-D focusing Multilayer Bragg-Fresnel Optics  

Microsoft Academic Search

We developed a new 2-D focusing x-ray lens consisting of a linear thin film Fresnel zones fabricated on a multilayer mirror bent along the direction of the x-ray beam. This unique hybrid optic combines diffraction and geometric focusing elements in one single device and eliminates the need for a second mirror in conventional K-B mirror based x-ray microprobes. The linear

Youli Li; Mario Yasa; Cyrus Safinya; Ernie Caine; Evelyn Hu; Jen Als-Nielsen; Andreas Freund

2003-01-01

378

High-brightness pump sources using 2D VCSEL arrays  

Microsoft Academic Search

Many applications require laser pump sources with high output power (tens to hundreds of Watts) in the smallest spot, with the smallest divergence. Such high-brightness pump sources typically use edge-emitting semiconductor lasers. However, it is also possible to use high-power two-dimensional vertical-cavity surfaceemitting laser (VCSEL) arrays for this purpose. Using a single 976nm 2D VCSEL array chip in an external

Jean-Francois Seurin; Guoyang Xu; Qing Wang; Baiming Guo; Robert van Leeuwen; Alexander Miglo; Prachi Pradhan; James D. Wynn; Viktor Khalfin; Chuni Ghosh

2010-01-01

379

Easily Computable Optimum Grasps in 2-D and 3-D  

Microsoft Academic Search

We consider the problem of finding optimum forceclosure grasps of two and three-dimensional objects.Our focus is on grasps which are useful in practice,namely grasps with a small number of fingers, withfriction at the contacts. Assuming frictional contactand rounded finger tips---very mild assumptions inpractice---we give new upper (and lower) bounds onthe number of fingers necessary to achieve force closuregrasps of 2-D

Brian Mirtich; John F. Canny

1994-01-01

380

Unitary quantum lattice gas representation of 2D quantum turbulence  

Microsoft Academic Search

Quantum vortex structures and energy cascades are examined for two dimensional quantum turbulence (2D QT) using a special unitary evolution algorithm. The qubit lattice gas (QLG) algorithm, is employed to simulate the weakly-coupled Bose-Einstein condensate (BEC) governed by the Gross-Pitaevskii (GP) equation. A parameter regime is uncovered in which, as in 3D QT, there is a very short Poincare recurrence

Bo Zhang; George Vahala; Linda Vahala; Min Soe

2011-01-01

381

Adaptive Multicast Wormhole Routing in 2D Mesh Multicomputers  

Microsoft Academic Search

. We study the issues of adaptive multicast wormhole routingin 2D mesh multicomputers. Three adaptive multicast wormhole routingstrategies are proposed and studied, which include minimal partial adaptive,minimal fully adaptive and nonminimal multicast routing methods.All the algorithms are shown to be deadlock-free. These are the firstdeadlock-free adaptive multicast wormhole routing algorithms ever proposed.A simulation study has been conducted that compares the

Xiaola Lin; Philip K. Mckinley; Abdol-hossein Esfahanian

1993-01-01

382

Transition in a 2-D lid-driven cavity flow  

Microsoft Academic Search

Direct numerical simulations about the transition process from laminar to chaotic flow in square lid-driven cavity flows are considered in this paper. The chaotic flow regime is reached after a sequence of successive supercritical Hopf bifurcations to periodic, quasi-periodic, inverse period-doubling, period-doubling, and chaotic self-sustained flow regimes. The numerical experiments are conducted by solving the 2-D incompressible Navier–Stokes equations with

Yih-Ferng Peng; Yuo-Hsien Shiau; Robert R. Hwang

2003-01-01

383

Theory and Applications of 2D Microcavity Lasers  

Microsoft Academic Search

We report a demonstration of lasing in a two-dimensional (2D) microcavity which is a semiconductor diode structure with a stadium shape finely formed by reactive-ion-etching technique and pumped by electric current injection. The laser exhibits output over a wide angle, although the fundamental lasing modes have highly complex wave structures which do not correspond to any simple set of rays

Takahisa Harayama; Takehiro Fukushima

2007-01-01

384

The analytical characterization of 2-D braided textile composites  

Microsoft Academic Search

An analytical model based on the unit cell was developed for the prediction of the geometric characteristics and three-dimensional (3-D) engineering constants of 2-D braided textile composites. The crimp yarn angle and the fiber-volume fraction were obtained from the geometric model. The elastic model utilizes coordinate transformation and the averaging of stiffness and compliance constants on the basis of the

Joon-Hyung Byun

2000-01-01

385

Multicolor symbology for remotely scannable 2D barcodes  

NASA Astrophysics Data System (ADS)

There has been much recent interest in mobile systems for augmented reality. However, existing visual tagging solutions are not robust at the low resolutions typical of current camera phones or at the low solid angles needed for "across-the-room" reality augmentation. In this paper, we propose a new 2D barcode symbology that uses multiple colors in order to address these challenges. We present preliminary results, showing the detection of example barcodes in this scheme over a range of angles.

Wissner-Gross, Alexander D.; Sullivan, Timothy M.

2008-03-01

386

Electronic and magnetic properties of 2D BCN nanostructures  

NASA Astrophysics Data System (ADS)

Recent developments of two-dimensional (2D) nanomaterials hold great promises for future electronics, optics and spintronics. Since the isolation and electronic characterization of graphene, other layered 2D crystals also have been synthesized. In particular, carbon can be combined with its neighboring atoms in the periodic table, boron and nitrogen as hexagonal BN (h-BN), to obtain hybrid BCN configurations. These BCN 2D nanostructures show a rich variety of physical properties, distinct from parent materials. Their electronic properties can in principle be tuned by varying the concentration of each of the three elements. We study electronic structures of a variety of 2D BCN nanostructures using hybrid functional HSE in density functional theory (DFT). We show that their electronic properties can be gradually tuned by composition and the atomic configuration of three elements. We demonstrate that the substitution-induced impurity states, associated with carbon atoms, and their interactions dictate the electronic structure and properties of C-doped h-BN. Stacking of localized impurity states in small C clusters embedded in h-BN forms a set of discrete energy levels in the wide gap of h-BN, leading to electronic structures of quantum dots made of carbon nano-domains for applications in optics and opto-electronics. We also show that half-metallic electron transport can be achieved by low concentration substitutional doping of only one sublattice of graphene by nitrogen or boron atoms. The delocalized spin-densities induced by the unpaired electrons at substitutional sites permeate only through the sublattice where the nitrogen (boron) atoms belong. For interacting nitrogen (boron) atoms located along the ``zigzag'' direction and in the same sublattice the ferro-magnetic spin-ordering is energetically favored, and substitution-induced impurity states selectively disturb the spin-polarized ?-orbital of that same sublattice.

Park, Hyoungki

2013-03-01

387

Perkutane, 2D-fluoroskopisch navigierte Sakrumverschraubung in Rückenlage  

Microsoft Academic Search

ZusammenfassungEinleitung  Der Einsatz navigierter Verfahren am Becken bleibt in Deutschland derzeit wenigen Zentren vorbehalten, wobei die Navigation vorwiegend zur perkutanen Verschraubung des hinteren Beckenrings in Rückenlage genutzt wird. Zielsetzung dieser Studie war es, technische Möglichkeiten und Grenzen der 2D-fluoroskopischen Navigation für diese Indikation zu evaluieren.Methodik  Eine konsekutive Serie von Patienten mit nicht bzw. gering verschobenen Verletzungen wurde im Rahmen einer prospektiven Studie

D. Briem; J. Windolf; J. M. Rueger

2007-01-01

388

From 2D towards 3D cartography of hollow organs  

Microsoft Academic Search

Endoscopy is a standard imaging modality commonly used in different medical fields like lesion diagnosis in hollow organs or mini-invasive surgery. Meanwhile, endoscopic data suffer from the fact that each image of a video-sequence only corresponds to a small 2D field of view. This paper presents a mosaicing algorithm leading to visually coherent large field of view maps. The ability

Christian Daul; Walter Blondel; Achraf Ben-Hamadou; Rosebet Miranda-Luna; Charles Soussen; Didier Wolf; François Guillemin

2010-01-01

389

Migrating from 2D to 3D in "Autograph"  

ERIC Educational Resources Information Center

|With both "Cabri" and "Autograph" now venturing into 3D, the dimension that previously was only demonstrated in the classroom with a lot of arm waving and crude wire cages can now be explored dynamically on screen. "Cabri 3D" concentrates on constructions, using the principles of Euclidian geometry, whereas "Autograph" creates objects using a…

Butler, Douglas

2006-01-01

390

Matching, Reconstructing and Grouping 3D Lines From Multiple Views Using Uncertain Projective Geometry  

Microsoft Academic Search

We present a geometric method for (i) matching 2D line seg- ments from multiple oriented images, (ii) optimally recon- structing 3D line segments and (iii) grouping 3D line seg- ments to corners. The proposed algorithm uses two developments in combin- ing projective geometry and statistics, which are described in this article: (i) the geometric entities points, lines and planes in

Stephan Heuel; Wolfgang Förstner

2001-01-01

391

2D depiction of nonbonding interactions for protein complexes.  

PubMed

A program called the 2D-GraLab is described for automatically generating schematic representation of nonbonding interactions across the protein binding interfaces. The input file of this program takes the standard PDB format, and the outputs are two-dimensional PostScript diagrams giving intuitive and informative description of the protein-protein interactions and their energetics properties, including hydrogen bond, salt bridge, van der Waals interaction, hydrophobic contact, pi-pi stacking, disulfide bond, desolvation effect, and loss of conformational entropy. To ensure these interaction information are determined accurately and reliably, methods and standalone programs employed in the 2D-GraLab are all widely used in the chemistry and biology community. The generated diagrams allow intuitive visualization of the interaction mode and binding specificity between two subunits in protein complexes, and by providing information on nonbonding energetics and geometric characteristics, the program offers the possibility of comparing different protein binding profiles in a detailed, objective, and quantitative manner. We expect that this 2D molecular graphics tool could be useful for the experimentalists and theoreticians interested in protein structure and protein engineering. PMID:18942722

Zhou, Peng; Tian, Feifei; Shang, Zhicai

2009-04-30

392

2D luminescence imaging of pH in vivo.  

PubMed

Luminescence imaging of biological parameters is an emerging field in biomedical sciences. Tools to study 2D pH distribution are needed to gain new insights into complex disease processes, such as wound healing and tumor metabolism. In recent years, luminescence-based methods for pH measurement have been developed. However, for in vivo applications, especially for studies on humans, biocompatibility and reliability under varying conditions have to be ensured. Here, we present a referenced luminescent sensor for 2D high-resolution imaging of pH in vivo. The ratiometric sensing scheme is based on time-domain luminescence imaging of FITC and ruthenium(II)tris-(4,7-diphenyl-1,10-phenanthroline). To create a biocompatible 2D sensor, these dyes were bound to or incorporated into microparticles (aminocellulose and polyacrylonitrile), and particles were immobilized in polyurethane hydrogel on transparent foils. We show sensor precision and validity by conducting in vitro and in vivo experiments, and we show the versatility in imaging pH during physiological and chronic cutaneous wound healing in humans. Implementation of this technique may open vistas in wound healing, tumor biology, and other biomedical fields. PMID:21262842

Schreml, Stephan; Meier, Robert J; Wolfbeis, Otto S; Landthaler, Michael; Szeimies, Rolf-Markus; Babilas, Philipp

2011-01-24

393

Comparison of 2D melting criteria in a colloidal system.  

PubMed

We use super-paramagnetic spherical particles which are arranged in a two-dimensional monolayer at a water/air interface to investigate the crystal to liquid phase transition. According to the KTHNY theory a crystal melts in thermal equilibrium by two continuous phase transitions into the isotropic liquid state with an intermediate phase, commonly known as the hexatic phase. We verify the significance of several criteria based on dynamical and structural properties to identify the crystal-hexatic and hexatic-isotropic liquid phase transitions for the same experimental data of the given setup. The criteria are the bond orientational correlation function, the Larson-Grier criterion, the 2D dynamic Lindemann parameter, the bond orientational susceptibility, the 2D Hansen-Verlet rule, the Löwen-Palberg-Simon criterion as well as a criterion based on the shape factor of Voronoi cells and Minkowski functionals. For our system with long-range repulsion, the bond order correlation function and bond order susceptibility work best to identify the hexatic-isotropic liquid transition and the 2D dynamic Lindemann parameter identifies unambiguously the hexatic-crystalline transition. PMID:23114280

Dillmann, Patrick; Maret, Georg; Keim, Peter

2012-10-31

394

Sensitivity of 2D Circulation to Longshore Bathymetric Variability  

NASA Astrophysics Data System (ADS)

When modeling nearshore circulation, it is convenient to make an assumption of longshore uniformity whenever possible. The alternatives, 2DH or 3D models for forecasting of longshore nonuniform natural systems, typically involve coding that is much more complex, longshore boundary conditions that can be burdensome, the availability of full 2D bathymetry to specify the bottom boundary condition over the entire domain, and large computational resources. However, the level of longshore bathymetric variability that can be considered small and, indeed, the sensitivity of model results to small details of alongshore bathymetry is not well known. In this work, we will investigate the sensitivity of nearshore circulation to details of the bathymetry. To generalize the problem, we will adopt low-order parameterizations of the bathymetry with the aim of identifying 2D bathymetric features (e.g. bar position and height) that control the 2D circulation. Using a simple 2DH circulation model based on the shallow water equations, we test the adequacy of our parameterizations to simulate actual experimental conditions by comparing to remote-sensing measurements of longshore currents at Duck, NC, from 2004-5. Following this, the sensitivity of results to parameterized alongshore variations in bathymetry will be examined.

Wilson, G.; Holman, R.; Ozkan-Haller, H.

2006-12-01

395

Volumetric elasticity imaging with a 2-D CMUT array.  

PubMed

This article reports the use of a two-dimensional (2-D) capacitive micro-machined ultrasound transducer (CMUT) to acquire radio-frequency (RF) echo data from relatively large volumes of a simple ultrasound phantom to compare three-dimensional (3-D) elasticity imaging methods. Typical 2-D motion tracking for elasticity image formation was compared with three different methods of 3-D motion tracking, with sum-squared difference (SSD) used as the similarity measure. Differences among the algorithms were the degree to which they tracked elevational motion: not at all (2-D search), planar search, combination of multiple planes and plane independent guided search. The cross-correlation between the predeformation and motion-compensated postdeformation RF echo fields was used to quantify motion tracking accuracy. The lesion contrast-to-noise ratio was used to quantify image quality. Tracking accuracy and strain image quality generally improved with increased tracking sophistication. When used as input for a 3-D modulus reconstruction, high quality 3-D displacement estimates yielded accurate and low noise modulus reconstruction. PMID:20510188

Fisher, Ted G; Hall, Timothy J; Panda, Satchi; Richards, Michael S; Barbone, Paul E; Jiang, Jingfeng; Resnick, Jeff; Barnes, Steve

2010-06-01

396

High precision calibration for 2D optical standard  

NASA Astrophysics Data System (ADS)

Photomask is a kind of 2-D optical standard with etched orthogonal coordinates made of a glass substrate chrominged or filmed with other metal. In order to solve the problems of measurement and traceability of ultra precision photomasks used in advanced manufacturing industry, 2-D photomask optical standard was calibrated in high precision laser two coordinate standard device. A high precision differential laser interferometer system was used for a length standard, a high magnification optical micro vision system was used for precision optical positioning feedback. In this paper, a image measurement model was purposed; A sampling window auto identification algorithm was designed. Grid stripe image could be identified and aimed at automatically by this algorithm. An edge detection method based on bidirection progressive scanning and 3-sigma rule for eliminating outliers in sampling window was found. Dirty point could be removed with effect. Edge detection error could be lowered. By this means, the measurement uncertainty of 2-D optical standard's ruling span was less than 0.3 micrometer (k=2).

Sun, Shuanghua; Gan, Xiaochuan; Xue, Zi; Ye, Xiaoyou; Wang, Heyan; Gao, Hongtang

2012-10-01

397

Region-based Statistical Analysis of 2D PAGE Images  

PubMed Central

A new comprehensive procedure for statistical analysis of two-dimensional polyacrylamide gel electrophoresis (2D PAGE) images is proposed, including protein region quantification, normalization and statistical analysis. Protein regions are defined by the master watershed map that is obtained from the mean gel. By working with these protein regions, the approach bypasses the current bottleneck in the analysis of 2D PAGE images: it does not require spot matching. Background correction is implemented in each protein region by local segmentation. Two-dimensional locally weighted smoothing (LOESS) is proposed to remove any systematic bias after quantification of protein regions. Proteins are separated into mutually independent sets based on detected correlations, and a multivariate analysis is used on each set to detect the group effect. A strategy for multiple hypothesis testing based on this multivariate approach combined with the usual Benjamini-Hochberg FDR procedure is formulated and applied to the differential analysis of 2D PAGE images. Each step in the analytical protocol is shown by using an actual dataset. The effectiveness of the proposed methodology is shown using simulated gels in comparison with the commercial software packages PDQuest and Dymension. We also introduce a new procedure for simulating gel images.

Li, Feng; Seillier-Moiseiwitsch, Francoise; Korostyshevskiy, Valeriy R.

2011-01-01

398

Characterization and modeling of 2D-glass micro-machining by spark-assisted chemical engraving (SACE) with constant velocity  

NASA Astrophysics Data System (ADS)

Spark-assisted chemical engraving (SACE) is an unconventional micro-machining technology based on electrochemical discharge used for micro-machining nonconductive materials. SACE 2D micro-machining with constant speed was used to machine micro-channels in glass. Parameters affecting the quality and geometry of the micro-channels machined by SACE technology with constant velocity were presented and the effect of each of the parameters was assessed. The effect of chemical etching on the geometry of micro-channels under different machining conditions has been studied, and a model is proposed for characterization of the micro-channels as a function of machining voltage and applied speed.

Fatanat Didar, Tohid; Dolatabadi, Ali; Wüthrich, Rolf

2008-06-01

399

DEEP SEARCH IN LINGUISTIC GEOMETRY  

Microsoft Academic Search

This paper is a new step in the development and application of the Linguistic Geometry. We investigate heuristics extracted in the form of hierarchical networks of planning paths of autonomous agents. Employing Linguistic Geometry tools the dynamic hierarchy of networks is represented as a hierarchy of formal attribute languages. The main ideas of this methodology are shown in this paper

Boris Stilman

400

GPS: Geometry, Probability, and Statistics  

ERIC Educational Resources Information Center

|It might be said that for most occupations there is now less of a need for mathematics than there was say fifty years ago. But, the author argues, geometry, probability, and statistics constitute essential knowledge for everyone. Maybe not the geometry of Euclid, but certainly geometrical ways of thinking that might enable us to describe the…

Field, Mike

2012-01-01

401

PROP Profile of Poisson Geometry  

NASA Astrophysics Data System (ADS)

It is shown that some classical local geometries are of infinity origin, i.e. their smooth formal germs are (homotopy) representations of cofibrant (di) operads in spaces concentrated in degree zero. In particular, they admit natural infinity generalizations when one considers homotopy representations of the (di) operads in generic differential graded spaces. Poisson geometry provides us with a simplest manifestation of this phenomenon.

Merkulov, S. A.

2006-02-01

402

Hamiltonian Gravity and Noncommutative Geometry  

NASA Astrophysics Data System (ADS)

A version of foliated spacetime is constructed in which the spatial geometry is described as a time-dependent noncommutative geometry. The ADM version of the gravitational action is expressed in terms of these variables. It is shown that the vector constraint is obtained without the need for an extraneous shift vector in the action.

Hawkins, Eli

403

Achievement in Writing Geometry Proofs.  

ERIC Educational Resources Information Center

|In 1981 a nationwide assessment of achievement in writing geometry proofs was conducted by the Cognitive Development and Achievement in Secondary School Geometry project. Over 1,500 students in 11 schools in 5 states participated. This paper describes the sample, instruments, grading procedures, and selected results. Results include: (1) at the…

Senk, Sharon L.

404

2-D analytic model for inductively coupled plasma sources. II. Effects of 2-D coupled damping and their applications  

Microsoft Academic Search

For pt.I see ibid., vol.23, no.1, p.65-73 (1995). In part I, we developed the electromagnetic model and analyzed the plasma kinetic behavior for the recently developed inductively coupled plasma sources (ICPS). The analytic forms demonstrated that the induced RF wave in ICPS is primarily dampened by a collisionless dissipation mechanism, In this paper, the 2-D coupled damping effect is further

Chwan-Hwa John Wu; Fa Dai

1995-01-01

405

A Nonrigid Kernel-Based Framework for 2D-3D Pose Estimation and 2D Image Segmentation  

PubMed Central

In this work, we present a nonrigid approach to jointly solving the tasks of 2D-3D pose estimation and 2D image segmentation. In general, most frameworks that couple both pose estimation and segmentation assume that one has exact knowledge of the 3D object. However, under nonideal conditions, this assumption may be violated if only a general class to which a given shape belongs is given (e.g., cars, boats, or planes). Thus, we propose to solve the 2D-3D pose estimation and 2D image segmentation via nonlinear manifold learning of 3D embedded shapes for a general class of objects or deformations for which one may not be able to associate a skeleton model. Thus, the novelty of our method is threefold: First, we present and derive a gradient flow for the task of nonrigid pose estimation and segmentation. Second, due to the possible nonlinear structures of one’s training set, we evolve the preimage obtained through kernel PCA for the task of shape analysis. Third, we show that the derivation for shape weights is general. This allows us to use various kernels, as well as other statistical learning methodologies, with only minimal changes needing to be made to the overall shape evolution scheme. In contrast with other techniques, we approach the nonrigid problem, which is an infinite-dimensional task, with a finite-dimensional optimization scheme. More importantly, we do not explicitly need to know the interaction between various shapes such as that needed for skeleton models as this is done implicitly through shape learning. We provide experimental results on several challenging pose estimation and segmentation scenarios.

Sandhu, Romeil; Dambreville, Samuel; Yezzi, Anthony; Tannenbaum, Allen

2013-01-01

406

The cytochrome P450 2D6 (CYP2D6) enzyme polymorphism: Screening costs and influence on clinical outcomes in psychiatry  

Microsoft Academic Search

Objectives: This study examined factors that affect cost, reliability, and the value of determining the cytochrome P450 2D6 (CYP2D6) polymorphism in clinical practice.Study design: The method of deoxyribonucleic acid isolation, sample preparation, oligonucleotide primers, and polymerase chain reaction procedures were scrutinized for their effect on CYP2D6 genotyping efforts. The determination of the CYP2D6 A, B, D, E, and T alleles

Shuqing Chen; Wen-Hwei Chou; Robert A. Blouin; Zhongping Mao; Laurie L. Humphries; Q. Craig Meek; John R. Neill; Walter L. Martin; Lon R. Hays; Peter J. Wedlund

1996-01-01

407

Comparative Differences of Pore Geometry from Planar and Volumetric Computer Tomography Images of Marine Sands  

NASA Astrophysics Data System (ADS)

Pore geometry of marine sands (pore sizes, pore size distributions, tortuosity, and coordination number) is a fundamental three-dimensional (3D) property that determines sediment permeability, hydraulic conductivity, acoustic sound speed, heat flow, and electrical conduction. Pore geometry assessments by volumetric analysis and two-dimensional (2D) image analysis measurements do not always agree, perhaps because of inherent limitations in the techniques. Image analysis measurements made from 2D computer tomography "slices" of a homogeneous and isotropic marine sand cannot completely assess the three-dimensional pore space. To assess the limitations of 2D images in predicting 3D properties, 2D and 3D computer tomography images of resin-impregnated ooids and quartz sands were evaluated by the same means. The images were segmented and a medial axis was created with 3DMA software. An algorithm that operates on the medial axis files was used to search the pore space and determine pore body (junction of pore connections) and throat (connections between the pore bodies) sizes and size distributions. The distribution of the coordination numbers (average number of pore connections per pore body) was also determined. Results of the 2D and 3D determinations reflect the homogeneity and isotropy of the sample, the robustness of the algorithms, and the representative size of the sample (area and volume). Significant differences between geometric properties determined from 2D and 3D images may enable enhanced predictions of effective porosity, tortuosity, and permeability, particularly in less homogeneous sediments.

Reed, A. H.; Al-Raoush, R.; Willson, C. S.; Cable, J. E.

2002-05-01

408

MORSE-CGA: a Monte Carlo radiation transport code with array geometry capability  

SciTech Connect

The MORSE-CG computer code system has been revised to add a new geometry module MARS, which is the combinatorial geometry package that allows multiple arrays for specifying geometries. The new code system is known as MORSE-CGA where CGA indicates Combinatorial Geometry Array. The PICTURE code, which makes printer plots of 2-D slices through a combinatorial geometry mock-up, has also been revised to handle the MARS array capability. This report will document the changes required in MORSE-CG and in PICTURE. Readers are referred to Sect. M9 of the SCALE document for details on MARS and to Sect. M13 of the SCALE document for details on PICTURE.

Emmett, M.B.

1985-04-01

409

New results in 2-D systems theory, part II: 2-D state-space models—Realization and the notions of controllability, observability, and minimality  

Microsoft Academic Search

In this part, a comparison between the different state-space models is presented. We discuss proper definitions of state, controllability and observability and their relations to minimality of 2-D systems. We also present new circuit realizations and 2-D digital filter hardware implementation of 2-D transfer functions.

Sun-Yuan Kung; B. C. Levy; M. Morf; T. Kailath

1977-01-01

410

1D + 1D ? 1D polyrotaxane, 2D + 2D ? 3D interpenetrated, and 3D self-penetrated divalent metal terephthalate bis(pyridylformyl)piperazine coordination polymers.  

PubMed

Divalent metal coordination polymers containing terephthalate (tere) and bis(4-pyridylformyl)piperazine (bpfp) show diverse and interesting two-dimensional (2D) interpenetrated, three-dimensional (3D) self-penetrated, or one-dimensional (1D) polyrotaxane topological features. Isostructural {[M(tere)(bpfp)(H(2)O)(2)]•4H(2)O}(n) phases (1, Zn; 2, Co) exhibit mutually inclined 2D + 2D ? 3D interpenetration of gridlike layers. {[Cd(4)(tere)(4)(bpfp)(3)(H(2)O)(2)]·8H(2)O}(n) (3) possesses a novel 3,4,8-connected trinodal self-penetrated network with (4.6(2))(2)(4(2)6(16)8(7)10(3))(4(2)6(4))(2) topology. [Zn(2)Cl(2)(tere)(bpfp)(2)](n) (4) is the first example of a 1D + 1D ? 1D polyrotaxane coordination polymer, to the best of our knowledge. Metal coordination geometry plays a crucial role in dictating the overall dimensionality in this system. Thermal decomposition behavior and luminescent properties of the d(10) configuration metal derivatives are also presented herein. PMID:21776990

Wang, Curtis Y; Wilseck, Zachary M; LaDuca, Robert L

2011-07-21

411

Crankshafts: using simple, flat C2h-symmetric molecules to direct the assembly of chiral 2D nanopatterns.  

PubMed

Linear D2h-symmetric bisisophthalic acids 1 and 2 and related substances have well-defined flattened structures, high affinities for graphite, and strong abilities to engage in specific intermolecular interactions. Their adsorption produces characteristic nanopatterns that reveal how 2D molecular organization can be controlled by reliable interadsorbate interactions such as hydrogen bonds when properly oriented by molecular geometry. In addition, the behavior of these compounds shows how large-scale organization can be obstructed by programming molecules to associate strongly according to competing motifs that have similar stability and can coexist smoothly without creating significant defects. Analogous new bisisophthalic acids 3a and 4a have similar associative properties, and their unique C2h-symmetric crankshaft geometry gives them the added ability to probe the poorly understood effect of chirality on molecular organization. Their adsorption shows how nanopatterns composed predictably of a single enantiomer can be obtained by depositing molecules that can respect established rules of association only by accepting neighbors of the same configuration. In addition, an analysis of the adsorption of crankshaft compounds 3a and 4a and their derivatives by STM reveals directly on the molecular level how kinetics and thermodynamics compete to control the crystallization of chiral compounds. In such ways, detailed studies of the adsorption of properly designed compounds on surfaces are proving to be a powerful way to discover and test rules that broadly govern molecular organization in both 2D and 3D. PMID:23092394

Zhou, Hui; Wuest, James D

2012-11-02

412

A system for a new two-dimensional code: Secure 2D code  

Microsoft Academic Search

A new 2D code called Secure 2D code is de- signed in this paper, both encoder and decoder are also pro- posed. Secure 2D code can store any kind of data and pro- vides high security. With regard to security, the input data is divided into two parts: general and secret. The general data is transformed into a 2D code

Chung-tsai Yeh; Ling-hwei Chen

1998-01-01

413

Room- and low-temperature magnetic properties of 2-D magnetite particle arrays  

NASA Astrophysics Data System (ADS)

Palaeomagnetic observations are being used in increasingly sophisticated geological and geophysical interpretations. It is therefore important to test the theories behind palaeomagnetic recording by rocks, and this can only be achieved using samples containing precisely controlled magnetic mineralogy, grain size and interparticle spacing, the last of which controls the degree of magnetostatic interactions within the samples. Here we report the room- and low temperature magnetic behaviour of a set of samples produced by the nano-scale patterning technique electron beam lithography. The samples consist of 2-D arrays of near-identical magnetite dots of various sizes, geometries and spatial configurations, with dot sizes from ranging from near the single domain threshold of 74-333 nm. We have made a series of magnetic measurements including hysteresis, first-order-reversal curve measurements and remanence acquisition, many as a function of temperature between 20 and 300 K, to quantify the samples’ behaviour to routine palaeomagnetic measurement procedures. We have also examined the behaviour of saturation isothermal remanences (SIRM) to cooling and warming cycling of the sample below room temperature. In addition, we investigated the samples’ responses to alternating-field demagnetization of room temperature induced SIRM, anhysteretic remanent magnetization (ARM) and partial ARM. ARM was used as a non-heating analogue for natural thermoremanence. Given the 2-D spatial distribution of the samples, in all the experiments we conducted both in-plane and out-of-plane measurements. Generally, the samples were found to display pseudo-single-domain hysteresis characteristics, but were found to be reliable recorders of weak-field remanences like ARM. For the closely packed samples, the samples’ magnetic response was highly dependent on measurement orientation.

Krása, David; Muxworthy, Adrian R.; Williams, Wyn

2011-04-01

414

Unusual formation of a stable 2D copper porphyrin network.  

PubMed

Copper(II) 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrin was obtained and characterized by means of cyclic voltammetry, electron paramagnetic resonance, Fourier transform infrared, and UV-visible spectroscopy. Three crystalline forms were grown and studied by means of X-ray diffraction methods (single crystal and powder). The highly electron-withdrawing effect of phosphoryl groups attached directly to the porphyrin macrocycle results in a self-assembling process, with formation of a stable 2D coordination network, which is unusual for copper(II) porphyrins. The resulting 2D structure is a rare example of an assembly based on copper(II) porphyrins where the copper(II) central metal ion is six-coordinated because of a weak interaction with two phosphoryl groups of adjacent porphyrins. The other polymorph of copper(II) 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrin contains individual (isolated) porphyrin molecules with four-coordinated copper(II) in a distorted porphyrin core. This polymorph can be obtained only by slow diffusion of a copper acetate/methanol solution into solutions of free base 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrin in chloroform. It converts to the 2D structure after dissolution in chloroform followed by consecutive crystallizations, using slow diffusion of hexane. A six-coordinated copper(II) porphyrin containing two axially coordinated dioxane molecules was also obtained and characterized by X-ray diffraction crystallography. The association of copper(II) 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrin in solution was also studied. PMID:23297696

Sinelshchikova, Anna A; Nefedov, Sergey E; Enakieva, Yulia Yu; Gorbunova, Yulia G; Tsivadze, Aslan Yu; Kadish, Karl M; Chen, Ping; Bessmertnykh-Lemeune, Alla; Stern, Christine; Guilard, Roger

2013-01-08

415

Digit ratio (2D:4D), salivary testosterone, and handedness.  

PubMed

The length of the index finger relative to that of the ring finger, the 2D:4D ratio, has been taken to be a marker of the amount of testosterone (T) that was present in the foetal environment (Manning, Scutt, Wilson, & Lewis-Jones, 1998). It has also been suggested (Geschwind & Galaburda, 1987) that elevated levels of foetal T are associated with left-handedness and that adult levels of circulating T might relate to foetal levels (Jamison, Meier, & Campbell, 1993). We used multiple regression analyses to investigate whether there is any relationship between either left or right hand 2D:4D ratio and handedness. We also examined whether adult levels of salivary T (or cortisol, used as a control hormone) predict digit ratio and/or handedness. Although the 2D:4D ratio of neither the left nor the right hand was related to handedness, the difference between the digit ratios of the right and left hands, D(R-L), was a significant predictor of handedness and of the performance difference between the hands on a peg-moving task, supporting previous findings (Manning & Peters, 2009; Manning et al., 1998; Manning, Trivers, Thornhill, & Singh, 2000; Stoyanov, Marinov, & Pashalieva, 2009). Adult circulating T levels did not predict the digit ratio of the left or right hand; nor was there a significant relationship between concentrations of salivary T (or cortisol) and either hand preference or asymmetry in manual skill. We suggest that the association between D(R-L) and hand preference arises because D(R-L) is a correlate of sensitivity to T in the developing foetus. PMID:20094940

Beaton, Alan A; Rudling, Nick; Kissling, Christian; Taurines, Regine; Thome, Johannes

2010-01-20

416

2D hybrid meshes for direct simulation Monte Carlo solvers  

NASA Astrophysics Data System (ADS)

The efficiency of the direct simulation Monte Carlo (DSMC) method decreases considerably if gas is not rarefied. In order to extend the application range of the DSMC method towards non-rarefied gas regimes, the computational efficiency of the DSMC method should be increased further. One of the most time consuming parts of the DSMC method is to determine which DSMC molecules are in close proximity. If this information is calculated quickly, the efficiency of the DSMC method will be increased. Although some meshless methods are proposed, mostly structured or non-structured meshes are used to obtain this information. The simplest DSMC solvers are limited with the structured meshes. In these types of solvers, molecule indexing according to the positions can be handled very fast using simple arithmetic operations. But structured meshes are geometry dependent. Complicated geometries require the use of unstructured meshes. In this case, DSMC molecules are traced cell-by-cell. Different cell-by-cell tracing techniques exist. But, these techniques require complicated trigonometric operations or search algorithms. Both techniques are computationally expensive. In this study, a hybrid mesh structure is proposed. Hybrid meshes are both less dependent on the geometry like unstructured meshes and computationally efficient like structured meshes.

Sengil, N.; Sengil, U.

2013-02-01

417

Comparing 2-D Electrophoresis Gels Across Internet Databases  

Microsoft Academic Search

\\u000a In refs.\\u000a 1-3 and in the previous edition of this book, we described a computerassisted visual method, Flicker, for comparing two two-dimensional\\u000a (2-D) protein gel images across the Internet, http:\\/\\/www.lecb.ncifcrf.gov\\/flicker\\/. This approach may be useful for comparing similar samples created in different laboratories to help putatively identify\\u000a or suggest protein spot identification. Two-dimension gels and associated databases are increasingly appearing

Peter F. Lemkin; Gregory C. Thornwall

418

2D Magneto-Optical Trapping of Diatomic Molecules  

NASA Astrophysics Data System (ADS)

We demonstrate one- and two-dimensional transverse laser cooling and magneto-optical trapping of the polar molecule yttrium (II) oxide (YO). In a 1D magneto-optical trap (MOT), we characterize the magneto-optical trapping force and decrease the transverse temperature by an order of magnitude, from 25 to 2 mK, limited by interaction time. In a 2D MOT, we enhance the intensity of the YO beam and reduce the transverse temperature in both transverse directions. The approach demonstrated here can be applied to many molecular species and can also be extended to 3D.

Hummon, Matthew T.; Yeo, Mark; Stuhl, Benjamin K.; Collopy, Alejandra L.; Xia, Yong; Ye, Jun

2013-04-01

419

Anomalous Diffusion in Strongly Coupled Quasi-2D Dusty Plasmas  

NASA Astrophysics Data System (ADS)

The motions of dust particles in a strongly coupled quasi-2D dusty plasma system are studied using direct optical monitoring. After the short-time antipersistent caged stage, the series excitation and relaxation of rotational motions follow the random phase stick-slip rule for the harder melting state but are the non-stick-slip type for the softer liquid state. The former leads to the persistent and then normal diffusion, and the latter to the almost normal diffusion. Their effects on the spatial correlation of particle displacement are also studied.

Juan, Wen-Tau; Lin, I.

1998-04-01

420

Black liquor gasification phase 2D final report  

SciTech Connect

This report covers work conducted by Rockwell International under Amendment 5 to Subcontract STR/DOE-12 of Cooperative Agreement DE-AC-05-80CS40341 between St. Regis Corporation (now Champion International) and the Department of Energy (DOE). The work has been designated Phase 2D of the overall program to differentiate it from prior work under the same subcontract. The overall program is aimed at demonstrating the feasibility of and providing design data for the Rockwell process for gasifying Kraft black liquor. In this process, concentrated black liquor is converted into low-Btu fuel gas and reduced melt by reaction with air in a specially designed gasification reactor.

Kohl, A.L.; Stewart, A.E.

1988-06-01

421

Constructing the 2D Adventure Game-Based Assessment System  

NASA Astrophysics Data System (ADS)

Due to the advanced computer and network technologies, it could be helpful to conduct an advanced distance learning system for learners to process their learning activities in anytime and anywhere. However, according to many research issues which found that the learning motivation is the most important element to encourage people into their learning and assessment activities. In this paper, we proposed the 2D Adventure Game-Based Assessment System which not only could draw people into their learning activities, but could help instructors easily to design and manage the related learning and assessment content.

Tang, Jing-Yao; Chen, Jui-Hung; Ku, David Tawei; Chao, Louis R.; Shih, Timothy K.; Weng, Martin M.

422

Rotational Invariance of the 2d Spin - Spin Correlation Function  

NASA Astrophysics Data System (ADS)

At the critical temperature in the 2d Ising model on the square lattice, we establish the rotational invariance of the spin-spin correlation function using the asymptotics of the spin-spin correlation function along special directions (McCoy and Wu in the two dimensional Ising model. Harvard University Press, Cambridge, 1973) and the finite difference Hirota equation for which the spin-spin correlation function is shown to satisfy (Perk in Phys Lett A 79:3-5, 1980; Perk in Proceedings of III international symposium on selected topics in statistical mechanics, Dubna, August 22-26, 1984, JINR, vol II, pp 138-151, 1985).

Pinson, Haru

2012-09-01

423

Analysis of 2-D cloaking problem using wave flow method  

NASA Astrophysics Data System (ADS)

Control problems for 2-D model of electromagnetic field describing the scattering of H-polarized electromagnetic waves in unbounded homogeneous medium containing anisotropic permeable object with covered boundary are considered. The role of control in control problem under study is played by boundary impedance. Quadratic tracking-type functionals for the field play the role of cost functionals. Solvability of the initial mixed boundary value problem for Helmholtz equation and control problems are studied. The uniqueness and stability of optimal solutions with respect to certain perturbations of both cost functional and incident field are established.

Alekseev, G. V.; Lobanov, A. V.

2013-10-01

424

Convective patterns in a 2d mantle convection simulation  

NASA Astrophysics Data System (ADS)

One of the great challenges in deep mantle physics is to develop a quantitative understanding of the dynamic processes that govern mantle convection, so that we can ascertain their respective influence from the data we have available from seismic tomography as well as magnetic observations. In this context, we explore the behaviour of convection patterns in a 2d Boussinesq fluid and analyze the emerging convection patterns in detail, so that we can later quantify the influence of more complex processes like anelasticity, complex rheologies and mineralogical composition.

Weismüller, Jens; Mohr, Marcus; Bunge, Hans-Peter

2013-04-01

425

Frustration and ground state entanglement in 2D lattices  

NASA Astrophysics Data System (ADS)

We investigate frustrated 2D lattice systems with an Ising-type interaction using exact diagonalization and Tensor Network techniques. The geometric frustration in these systems is controlled by the couplings of the Hamiltonian. We study the ground state entanglement for the combination of model parameters inducing a higher degree of frustrated interactions, showing relations between the frustration and the amount of quantum correlations present along different partitions of the lattice. Using the connection between ground state entanglement and the classical simulation of quantum systems, these results point to scenarios where simulating local systems is supposed to be hard.

Garcia, Artur; Latorre, Jose I.

2013-03-01

426

Nonstationary 2D models of the electron-wave interaction  

NASA Astrophysics Data System (ADS)

A 2D nonstationary model of induced emission of ribbon-shaped electron beams and clusters in free space is developed in the quasi-optical approximation. On the basis of this model, the problem of enhancement of a short electromagnetic pulse propagating along a quasi-stationary ribbon electron flow, the theory of a BWT-type oscillator with radiation channeling by an electron beam, and the process of collective acceleration of a short electron cluster in the field of an intense cocurrent wave are considered.

Baryshev, V. R.; Ginzburg, N. S.; Sergeev, A. S.

2008-05-01

427

2-D Unitary ESPRIT-Like Direction-of-Arrival (DOA) Estimation for Coherent Signals with a Uniform Rectangular Array  

PubMed Central

A unitary transformation-based algorithm is proposed for two-dimensional (2-D) direction-of-arrival (DOA) estimation of coherent signals. The problem is solved by reorganizing the covariance matrix into a block Hankel one for decorrelation first and then reconstructing a new matrix to facilitate the unitary transformation. By multiplying unitary matrices, eigenvalue decomposition and singular value decomposition are both transformed into real-valued, so that the computational complexity can be reduced significantly. In addition, a fast and computationally attractive realization of the 2-D unitary transformation is given by making a Kronecker product of the 1-D matrices. Compared with the existing 2-D algorithms, our scheme is more efficient in computation and less restrictive on the array geometry. The processing of the received data matrix before unitary transformation combines the estimation of signal parameters via rotational invariance techniques (ESPRIT)-Like method and the forward-backward averaging, which can decorrelate the impinging signals more thoroughly. Simulation results and computational order analysis are presented to verify the validity and effectiveness of the proposed algorithm.

Ren, Shiwei; Ma, Xiaochuan; Yan, Shefeng; Hao, Chengpeng

2013-01-01

428

2-D HARMONIC RETRIEVAL IN MULTIPLICATIVE AND ADDITIVE NOISE BASED ON CHIRP Z-TRANSFORM  

Microsoft Academic Search

The two-dimensional (2-D) harmonic retrieval method in multiplicative and additive noise based on 2-D chirp z-transform (CZT) is discussed in this paper. Unlike 2-D FFT, the 2-D CZT can improve the spectral resolution without increasing the size of the observation data and fine the spectra of 2-D harmonics in multiplicative and additive noise. Hence, the resolution and accuracy of the

Shiyong Yang; Hongwei Li; Cheng Wu; Zhiming Li

2006-01-01

429

Expression of four rat CYP2D isoforms in Saccharomyces cerevisiae and their catalytic specificity.  

PubMed

We cloned four cDNAs belonging to the CYP2D subfamily to express these enzymes in yeast cells and to compare their catalytic activities simultaneously. Three are believed to be alleles of CYP2D1, 2D2, and 2D3, respectively, based on high nucleotide sequence similarity, while CYP2D4 had both sequences of CYP2D4 and CYP2D18. Expression plasmids carrying CYP2D cDNAs were transformed into Saccharomyces cerevisiae. Typical P450 CO-difference spectra with absorbance maximum at 448 nm were recorded with microsomal preparations from the yeast cells expressing the four CYP2D forms. A catalytic study of these CYP2D forms was done with debrisoquine, bufuralol, and lidocaine. CYP2D2 had the highest debrisoquine 4-hydroxylation (2.2 nmol/min/nmol P450) activity, similar to that (2.2 nmol/min/nmol) of human CYP2D6 expressed in yeast cells. CYP2D3 had high lidocaine N-deethylation (43 nmol/min/nmol P450) activity, and both CYP2D3 and 2D2 exhibited high lidocaine 3-hydroxylation (2.4 and 1.6 nmol/min/nmol P450, respectively) activity. Bufuralol 1'-hydroxylation catalytic capabilities were comparable among the four isoforms. The activity of CYP2D1 was relatively low toward the three substrates (debrisoquine, 0.091; bufuralol, 1.5; lidocaine 3-hydroxylation, 0.019; lidocaine N-deethylation, 2.8 nmol/min/nmol P450). These findings indicate that debrisoquine, a typical substrate for CYP2D forms, was mainly metabolized by CYP2D2 but not CYP2D1 in rat liver and that the CYP2D forms have different substrate specificity. PMID:9434752

Wan, J; Imaoka, S; Chow, T; Hiroi, T; Yabusaki, Y; Funae, Y

1997-12-15

430

Response to hydrocodone, codeine and oxycodone in a CYP2D6 poor metabolizer  

Microsoft Academic Search

Codeine is metabolized by the cytochrome P450 2D6 (CYP2D6) to morphine. Codeine is a much weaker agonist at ? opioid receptors than morphine. Therefore, codeine analgesia is highly dependent on CYP2D6 activity. Large prospective studies in the clinical environment do not exist, but it appears reasonable to avoid codeine use in CYP2D6 poor metabolizers (PMs). CYP2D6 metabolizes other opioid analgesics,

Margaret T. Susce; Elaina Murray-Carmichael; Jose de Leon

2006-01-01

431

Grade 1 Practice Problems: Geometry  

NSDL National Science Digital Library

This page contains 12 problems in geometry from the Port Angeles School District in Washington state. Links to state GLEs and revised standards are provided. Topics covered include position and shape.

2011-01-01

432

The Dilemma of Descriptive Geometry  

ERIC Educational Resources Information Center

Proposes that engineering students undergo a preparatory summer school training program in fundamentals of engineering drawing, descriptive geometry, and mathematics prior to being admitted to regular engineering studies. (SL)

Boleslavski, Moshe

1977-01-01

433

Lorentzian approach to noncommutative geometry  

NASA Astrophysics Data System (ADS)

This thesis concerns the research on a Lorentzian generalization of Alain Connes' noncommutative geometry. In the first chapter, we present an introduction to noncommutative geometry within the context of unification theories. The second chapter is dedicated to the basic elements of noncommutative geometry as the noncommutative integral, the Riemannian distance function and spectral triples. In the last chapter, we investigate the problem of the generalization to Lorentzian manifolds. We present a first step of generalization of the distance function with the use of a global timelike eikonal condition. Then we set the first axioms of a temporal Lorentzian spectral triple as a generalization of a pseudo-Riemannian spectral triple together with a notion of global time in noncommutative geometry.

Franco, Nicolas

2011-08-01

434

Emergent geometry from quantized spacetime  

SciTech Connect

We examine the picture of emergent geometry arising from a mass-deformed matrix model. Because of the mass deformation, a vacuum geometry turns out to be a constant curvature spacetime such as d-dimensional sphere and (anti-)de Sitter spaces. We show that the mass-deformed matrix model giving rise to the constant curvature spacetime can be derived from the d-dimensional Snyder algebra. The emergent geometry beautifully confirms all the rationale inferred from the algebraic point of view that the d-dimensional Snyder algebra is equivalent to the Lorentz algebra in (d+1)-dimensional flat spacetime. For example, a vacuum geometry of the mass-deformed matrix model is completely described by a G-invariant metric of coset manifolds G/H defined by the Snyder algebra. We also discuss a nonlinear deformation of the Snyder algebra.

Yang, Hyun Seok [School of Physics, Korea Institute for Advanced Study, Seoul 130-012 (Korea, Republic of); Institute for the Early Universe, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Sivakumar, M. [School of Physics, University of Hyderabad, Hyderabad 500046 (India)

2010-08-15

435

Cynomolgus monkey CYP2D44 newly identified in liver, metabolizes bufuralol, and dextromethorphan.  

PubMed

The cynomolgus monkey is used in drug metabolism studies, because of its evolutionary closeness to human, including cytochrome P450. Cynomolgus monkey CYP2D17, highly homologous to human CYP2D6, has been identified and characterized. Here, we report characterization of another CYP2D, CYP2D44, identified in cynomolgus monkey liver. The CYP2D44 cDNA contained an open reading frame of 497 amino acids sharing high sequence identity (87-93%) with other primate CYP2Ds. CYP2D44 mRNA was predominantly expressed in liver, similar to CYP2D17 mRNA. CYP2D17 and CYP2D44 form a gene cluster in the genome, similar to human CYP2Ds. Metabolic assays of the CYP2D17 and CYP2D44 proteins heterologously expressed in Escherichia coli indicated that CYP2D44 metabolized human CYP2D6 substrates, bufuralol and dextromethorphan (bufuralol 1'-hydroxylation and dextromethorphan O-demethylation) but to a lesser extent than CYP2D17. Kinetic analysis of dextromethorphan metabolism indicated that the apparent K(m) and V(max) of CYP2D17 and CYP2D44 catalyzed O-demethylation were similar, and, the V(max) values of CYP2D17 and CYP2D44 catalyzed N-demethylation (which human CYP2D6 catalyzes much less effectively) were similar, but the apparent K(m) of the CYP2D44 reaction was higher. Western blot analysis showed that CYP2D proteins were expressed in cynomolgus and rhesus monkey liver as well as in human and marmoset liver. Similar to CYP2D6, CYP2D44 copy number varied among the eight cynomolgus monkeys and four rhesus monkeys used in this study. These results indicated that CYP2D44, together with CYP2D17, had functional characteristics similar to those of human CYP2D6 but measurably differed in dextromethorphan N-demethylation, suggesting its importance for CYP2D-dependent drug metabolism in macaque. PMID:20501912

Uno, Yasuhiro; Uehara, Shotaro; Kohara, Sakae; Murayama, Norie; Yamazaki, Hiroshi

2010-05-25

436

2D/3D image (facial) comparison using camera matching.  

PubMed

A problem in forensic facial comparison of images of perpetrators and suspects is that distances between fixed anatomical points in the face, which form a good starting point for objective, anthropometric comparison, vary strongly according to the position and orientation of the camera. In case of a cooperating suspect, a 3D image may be taken using e.g. a laser scanning device. By projecting the 3D image onto a 2D image with the suspect's head in the same pose as that of the perpetrator, using the same focal length and pixel aspect ratio, numerical comparison of (ratios of) distances between fixed points becomes feasible. An experiment was performed in which, starting from two 3D scans and one 2D image of two colleagues, male and female, and using seven fixed anatomical locations in the face, comparisons were made for the matching and non-matching case. Using this method, the non-matching pair cannot be distinguished from the matching pair of faces. Facial expression and resolution of images were all more or less optimal, and the results of the study are not encouraging for the use of anthropometric arguments in the identification process. More research needs to be done though on larger sets of facial comparisons. PMID:16337353

Goos, Mirelle I M; Alberink, Ivo B; Ruifrok, Arnout C C

2005-12-06

437

2D NMR-spectroscopic screening reveals polyketides in ladybugs  

PubMed Central

Small molecules of biological origin continue to yield the most promising leads for drug design, but systematic approaches for exploring nature’s cache of structural diversity are lacking. Here, we demonstrate the use of 2D NMR spectroscopy to screen a library of biorationally selected insect metabolite samples for partial structures indicating the presence of new chemical entities. This NMR-spectroscopic survey enabled detection of novel compounds in complex metabolite mixtures without prior fractionation or isolation. Our screen led to discovery and subsequent isolation of two families of tricyclic pyrones in Delphastus catalinae, a tiny ladybird beetle that is employed commercially as a biological pest control agent. The D. catalinae pyrones are based on 23-carbon polyketide chains forming 1,11-dioxo-2,6,10-trioxaanthracene and 4,8-dioxo-1,9,13-trioxaanthracene derivatives, representing ring systems not previously found in nature. This study highlights the utility of 2D NMR-spectroscopic screening for exploring nature’s structure space and suggests that insect metabolomes remain vastly underexplored.

Deyrup, Stephen T.; Eckman, Laura E.; McCarthy, Patrick H.; Smedley, Scott R.; Meinwald, Jerrold; Schroeder, Frank C.

2011-01-01

438

Syndrome identification based on 2D analysis software.  

PubMed

Clinical evaluation of children with developmental delay continues to present a challenge to the clinicians. In many cases, the face provides important information to diagnose a condition. However, database support with respect to facial traits is limited at present. Computer-based analyses of 2D and 3D representations of faces have been developed, but it is unclear how well a larger number of conditions can be handled by such systems. We have therefore analysed 2D pictures of patients each being affected with one of 10 syndromes (fragile X syndrome; Cornelia de Lange syndrome; Williams-Beuren syndrome; Prader-Willi syndrome; Mucopolysaccharidosis type III; Cri-du-chat syndrome; Smith-Lemli-Opitz syndrome; Sotos syndrome; Microdeletion 22q11.2; Noonan syndrome). We can show that a classification accuracy of >75% can be achieved for a computer-based diagnosis among the 10 syndromes, which is about the same accuracy achieved for five syndromes in a previous study. Pairwise discrimination of syndromes ranges from 80 to 99%. Furthermore, we can demonstrate that the criteria used by the computer decisions match clinical observations in many cases. These findings indicate that computer-based picture analysis might be a helpful addition to existing database systems, which are meant to assist in syndrome diagnosis, especially as data acquisition is straightforward and involves off-the-shelf digital camera equipment. PMID:16773127

Boehringer, Stefan; Vollmar, Tobias; Tasse, Christiane; Wurtz, Rolf P; Gillessen-Kaesbach, Gabriele; Horsthemke, Bernhard; Wieczorek, Dagmar

2006-06-14

439

Dynamic sector processing using 2D assignment for rotating radars  

NASA Astrophysics Data System (ADS)

Electronically scanned array radars as well as mechanically steered rotating antennas return measurements with different time stamps during the same scan while sweeping form one region to another. Data association algorithms process the measurements at the end of the scan in order to satisfy the common one measurement per track assumption. Data processing at the end of a full scan resulted in delayed target state update. This issue becomes more apparent while tracking fast moving targets with low scan rate sensors. In this paper, we present new dynamic sector processing algorithm using 2D assignment for continuously scanning radars. A complete scan can be divided into sectors, which could be as small as a single detection, depending on the scanning rate and sparsity of targets. Data association followed by filtering and target state update is done dynamically while sweeping from one end to another. Along with the benefit of immediate track updates, continuous tracking results in challenges such as multiple targets spanning multiple sectors and targets crossing consecutive sectors. Also, associations performed in the current sector may require changes in association done in previous sectors. Such difficulties are resolved by the proposed 2D assignment algorithm that implements an incremental Hungarian assignment technique. The algorithm offers flexibility with respect to assignment variables for fusing of measurements received in consecutive sectors. Furthermore the proposed technique can be extended to multiframe assignment for jointly processing data from multiple scanning radars. Experimental results based on rotating radars are presented.

Habtemariam, Biruk K.; Tharmarasa, R.; Pelletier, M.; Kirubarajan, T.

2011-09-01

440

MAZE. Generates 2D Input for DYNA NIKE & TOPAZ  

SciTech Connect

MAZE is an interactive input generator for two-dimensional finite element codes. MAZE has three phases. In the first phase, lines and parts are defined. The first phase is terminated by the `ASSM` or `PASSM` command which merges all parts. In the second phase, boundary conditions may be specified, slidelines may be defined, parts may be merged to eliminate nodes along common interfaces, boundary nodes may be moved for graded zoning, the mesh may be smoothed, and load curves may be defined. The second phase is terminated by the `WBCD` command which causes MAZE to write the output file as soon as the `T` terminate command is typed. In the third phase, material properties may be defined. Commands that apply to the first phase may not be used in the second or third; likewise, commands that apply in the second may not be used in the first and third, or commands that apply in the third in the first and second. Nine commands - TV, Z, GSET, PLOTS, GRID, NOGRID, FRAME, NOFRAME, and RJET are available in all phases. Comments may be added anywhere in the input stream by prefacing the comment with `C`. Any DYNA2D or NIKE2D material and equation-of-state model may be defined via the MAT and EOS commands, respectively. MAZE may be terminated after phase two; it is not necessary to define the materials.

Hallquist, J.O. [Lawrence Livermore National Lab., CA (United States)

1992-02-10

441

Exactly solvable models for 2D interacting fermions  

NASA Astrophysics Data System (ADS)

I discuss many-body models for correlated fermions in two space dimensions which can be solved exactly using group theory. The simplest example is a model of a quantum Hall system: two-dimensional (2D) fermions in a constant magnetic field and a particular non-local four-point interaction. It is exactly solvable due to a dynamical symmetry corresponding to the Lie algebra glinfin oplus glinfin. There is an algorithm to construct all energy eigenvalues and eigenfunctions of this model. The latter are, in general, many-body states with spatial correlations. The model also has a non-trivial zero temperature phase diagram. I point out that this QH model can be obtained from a more realistic one using a truncation procedure generalizing a similar one leading to mean field theory. Applying this truncation procedure to other 2D fermion models I obtain various simplified models of increasing complexity which generalize mean field theory by taking into account non-trivial correlations but nevertheless are treatable by exact methods. Contribution to RAQIS'03, Annecy-le-Vieux, March 2003.

Langmann, Edwin

2004-01-01

442

2D Numerical MHD Models of Solar Explosive Events  

NASA Astrophysics Data System (ADS)

Observations of the Sun reveal a great variety of dynamic phenomena interpretable as a manifestation of magnetic reconnection. These range from small-scale 'Explosive events' seen in the 'quiet' Sun, through violent flares observed in active regions. The high degree of complexity of the magnetic field inferred from observations may locally produce a fruitful environment for the process of magnetic reconnection to take place. Explosive events are associated with regions undergoing magnetic flux cancellation. This thesis presents a 2-dimensional (2D) numerical study devoted to explore the idea that the salient spectral signatures seen in explosive events are most probably caused by bi-directional outflow jets as a results of an ongoing magnetic reconnection. In order to provide qualitative results needed for the better physical interpretation of solar explosive events, several models intended to represent a 'quiet' Sun transition of solar explosive events, several models intended to represent a 'quiet' Sun transition region undergoing magnetic reconnection are examined, in both unstratified and gravitationally stratified atmospheres. The magnetic reconnection is initiated in an ad hoc manner, and the dynamic evolution is followed by numerically solving the equations of 2D dissipative magnetohydrodynamics (MHD), including the effects of field-aligned thermal conduction, radiative losses, volumetric heating, and anomalous resistivity.

Roussev, I.

2001-10-01

443

2-D contour perception resulting from kinetic occlusion.  

PubMed

Kinetic occlusion, the progressive deletion or accretion of texture elements as one surface covers or uncovers another, has been shown to be an important source of information for determining depth order. In the present study, the importance of this information for 2-D contour perception was examined. In Experiment 1, subjects were asked to discriminate four different target shapes defined solely by kinetic occlusion. Discrimination increased with an increase in texture density and velocity, with density as the major factor. In Experiment 2, the targets were defined by static untextured regions as well as by kinetic occlusion. Overall, accuracy was similar to that found in Experiment 1, indicating that the presence of static information had little impact on accuracy. In Experiment 3, subjects were unable to discriminate among the four targets when presented with static versions of the displays used in Experiment 2. The results from these experiments indicate that kinetic occlusion can be used for discrimination of different 2-D shapes and that density has a more important role in determining accuracy than velocity. PMID:2755761

Andersen, G J; Cortese, J M

1989-07-01

444

Interactive 2D to 3D stereoscopic image synthesis  

NASA Astrophysics Data System (ADS)

Advances in stereoscopic display technologies, graphic card devices, and digital imaging algorithms have opened up new possibilities in synthesizing stereoscopic images. The power of today"s DirectX/OpenGL optimized graphics cards together with adapting new and creative imaging tools found in software products such as Adobe Photoshop, provide a powerful environment for converting planar drawings and photographs into stereoscopic images. The basis for such a creative process is the focus of this paper. This article presents a novel technique, which uses advanced imaging features and custom Windows-based software that utilizes the Direct X 9 API to provide the user with an interactive stereo image synthesizer. By creating an accurate and interactive world scene with moveable and flexible depth map altered textured surfaces, perspective stereoscopic cameras with both visible frustums and zero parallax planes, a user can precisely model a virtual three-dimensional representation of a real-world scene. Current versions of Adobe Photoshop provide a creative user with a rich assortment of tools needed to highlight elements of a 2D image, simulate hidden areas, and creatively shape them for a 3D scene representation. The technique described has been implemented as a Photoshop plug-in and thus allows for a seamless transition of these 2D image elements into 3D surfaces, which are subsequently rendered to create stereoscopic views.

Feldman, Mark H.; Lipton, Lenny

2005-03-01

445

Mass loss in 2D rotating stellar models  

SciTech Connect

Radiatively driven mass loss is an important factor in the evolution of massive stars . The mass loss rates depend on a number of stellar parameters, including the effective temperature and luminosity. Massive stars are also often rapidly rotating, which affects their structure and evolution. In sufficiently rapidly rotating stars, both the effective temperature and radius vary significantly as a function of latitude, and hence mass loss rates can vary appreciably between the poles and the equator. In this work, we discuss the addition of mass loss to a 2D stellar evolution code (ROTORC) and compare evolution sequences with and without mass loss. Preliminary results indicate that a full 2D calculation of mass loss using the local effective temperature and luminosity can significantly affect the distribution of mass loss in rotating main sequence stars. More mass is lost from the pole than predicted by 1D models, while less mass is lost at the equator. This change in the distribution of mass loss will affect the angular momentum loss, the surface temperature and luminosity, and even the interior structure of the star. After a single mass loss event, these effects are small, but can be expected to accumulate over the course of the main sequence evolution.

Lovekin, Caterine [Los Alamos National Laboratory; Deupree, Bob [ST MARY'S UNIV.

2010-10-05

446

CFD Modelling of Particle Mixtures in a 2D CFB  

NASA Astrophysics Data System (ADS)

The capability of Fluent 6.2.16 to simulate particle mixtures in a laboratory scale 2D circulating fluidized bed (CFB) unit has been tested. In the simulations, the solids were described as one or two particle phases. The loading ratio of small to large particles, particle diameters and the gas inflow velocity were varied. The 40 cm wide and 3 m high 2D CFB was modeled using a grid with 31080 cells. The outflow of particles at the top of the CFB was monitored and emanated particles were fed back to the riser through a return duct. The paper presents the segregation patterns of the particle phases obtained from the simulations. When the fraction of large particles was 50% or larger, large particles segregated, as expected, to the wall regions and to the bottom part of the riser. However, when the fraction of large particles was 10%, an excess of large particles was found in the upper half of the riser. The explanation for this unexpected phenomenon was found in the distribution of the large particles between the slow clusters and the faster moving lean suspension.

Seppälä, M.; Kallio, S.

447

Evidence for 2-D Turbulence in the Lower Thermosphere (Invited)  

NASA Astrophysics Data System (ADS)

One of the most remarkable observations during the last decade involves events in the polar regions after solstice launches of the space shuttle. Two well-documented events occurred in January 2003 and in August 2007. The experimental results will be summarized and include lidar and visual detection of noctilucent clouds (NLC), rapid expansion and net transport of the shuttle plume toward the poles, and intense iron atom and sporadic E layers over Antarctica in one event and over the Arctic in another. There are at least two competing explanations and perhaps others will be presented in this session. The rapid expansion of the plume can be explained by upward hydrogen transport where it then can diffuse horizontally. Other features seem more problematic. We argue that 2-D turbulence can explain a number of these features. The 90-110 km altitude range where the shuttle burns is known to have very high winds and wind shears. One experiment showed that these high winds were quite different only 400 km away, indicating horizontal shears. The 2-D turbulence theory, first studied by G. K. Batchelor, has two important features: (a) enhanced diffusion over 3-D turbulence and (b) an inverse cascade that leads to very large eddies in the flow, even if the input scale is modest. This process could thus explain the expansion and transport, even of the iron, which, it seems, cannot duplicate the hydrogen behavior. The idea that a magnetized Rossby wave might be the input source of mesoscale structure will be addressed.

Kelley, M. C.; Varney, R. H.; Seyler, C. E.

2010-12-01

448

Automatic segmentation of scaling in 2-D psoriasis skin images.  

PubMed

Psoriasis is a chronic inflammatory skin disease that affects over 3% of the population. Various methods are currently used to evaluate psoriasis severity and to monitor therapeutic response. The PASI system of scoring is widely used for evaluating psoriasis severity. It employs a visual analogue scale to score the thickness, redness (erythema), and scaling of psoriasis lesions. However, PASI scores are subjective and suffer from poor inter- and intra-observer concordance. As an integral part of developing a reliable evaluation method for psoriasis, an algorithm is presented for segmenting scaling in 2-D digital images. The algorithm is believed to be the first to localize scaling directly in 2-D digital images. The scaling segmentation problem is treated as a classification and parameter estimation problem. A Markov random field (MRF) is used to smooth a pixel-wise classification from a support vector machine (SVM) that utilizes a feature space derived from image color and scaling texture. The training sets for the SVM are collected directly from the image being analyzed giving the algorithm more resilience to variations in lighting and skin type. The algorithm is shown to give reliable segmentation results when evaluated with images with different lighting conditions, skin types, and psoriasis types. PMID:23288330

Lu, Juan; Kazmierczak, Ed; Manton, Jonathan H; Sinclair, Rodney

2012-12-24

449

Meshfree natural vibration analysis of 2D structures  

NASA Astrophysics Data System (ADS)

Determination of resonance frequencies and vibration modes of mechanical structures is one of the most important tasks in the product design procedure. The main goal of this paper is to describe a pioneering application of the solution structure method (SSM) to 2D structural natural vibration analysis problems and investigate the numerical properties of the method. SSM is a meshfree method which enables construction of the solutions to the engineering problems that satisfy exactly all prescribed boundary conditions. This method is capable of using spatial meshes that do not conform to the shape of a geometric model. Instead of using the grid nodes to enforce boundary conditions, it employs distance fields to the geometric boundaries and combines them with the basis functions and prescribed boundary conditions at run time. This defines unprecedented geometric flexibility of the SSM as well as the complete automation of the solution procedure. In the paper we will explain the key points of the SSM as well as investigate the accuracy and convergence of the proposed approach by comparing our results with the ones obtained using analytical methods or traditional finite element analysis. Despite in this paper we are dealing with 2D in-plane vibrations, the proposed approach has a straightforward generalization to model vibrations of 3D structures.

Kosta, Tomislav; Tsukanov, Igor

2013-08-01

450

MESH2D GRID GENERATOR DESIGN AND USE  

SciTech Connect

Mesh2d is a Fortran90 program designed to generate two-dimensional structured grids of the form [x(i),y(i,j)] where [x,y] are grid coordinates identified by indices (i,j). The x(i) coordinates alone can be used to specify a one-dimensional grid. Because the x-coordinates vary only with the i index, a two-dimensional grid is composed in part of straight vertical lines. However, the nominally horizontal y(i,j{sub 0}) coordinates along index i are permitted to undulate or otherwise vary. Mesh2d also assigns an integer material type to each grid cell, mtyp(i,j), in a user-specified manner. The complete grid is specified through three separate input files defining the x(i), y(i,j), and mtyp(i,j) variations. The overall mesh is constructed from grid zones that are typically then subdivided into a collection of smaller grid cells. The grid zones usually correspond to distinct materials or larger-scale geometric shapes. The structured grid zones are identified through uppercase indices (I,J). Subdivision of zonal regions into grid cells can be done uniformly, or nonuniformly using either a polynomial or geometric skewing algorithm. Grid cells may be concentrated backward, forward, or toward both ends. Figure 1 illustrates the above concepts in the context of a simple four zone grid.

Flach, G.; Smith, F.

2012-01-20

451

Performance analysis of 2D-barcode-enhanced documents  

NASA Astrophysics Data System (ADS)

Barcode-enhanced documents are used in office automation and in applications involving shipping manifests, vehicle registration forms, photo-ID, etc. They consist of human readable text and machine readable barcodes, which duplicates the text in a secure machine-readable form. Two-dimensional barcodes are used when it is beneficial to encode a large amount of data. The advantage of barcode-enhanced document over OCR is that the rejection and misdecode rates are several orders of magnitude smaller. This paper analyzes the performance of 2-D barcode-enhanced documents, characterized by the rates of correct decode, rejection, and misdecode of the 2-D barcode. Primarily using PDF417 as an example, we show how these rates are determined by the parameters used in the encoding process and the decoder design, and from the environment. We find that in real-world applications the misdecode rates are extremely low, and thus for all practical purposes the limiting parameter is the rejection rate.

He, Jackson D.; Li, Chung-Chi J.; Kumar, Sundeep; Katz, Joseph

1995-03-01

452

Drift waves in stellarator geometry  

SciTech Connect

Drift waves are investigated in a real three-dimensional stellarator geometry. A linear system, based on the cold ion fluid model and a ballooning mode formalism, is solved numerically in the geometry of the stellarator H1-NF. The spectra of stable and unstable modes, as well as localization, are discussed. The dependence of the spectrum of the unstable modes on the wavevector, plasma density variation, and the location in the plasma is presented.

Persson, M.; Nadeem, M.; Lewandowski, J.L.V.; Gardner, H.J.

2000-02-07

453

Tensor Network States and Geometry  

Microsoft Academic Search

Tensor network states are used to approximate ground states of local Hamiltonians on a lattice in D spatial dimensions. Different types of tensor network states can be seen to generate different geometries. Matrix product\\u000a states (MPS) in D=1 dimensions, as well as projected entangled pair states (PEPS) in D>1 dimensions, reproduce the D-dimensional physical geometry of the lattice model; in

G. Evenbly; G. Vidal

2011-01-01

454

Influence of the Geometry on Mantle Convection Models  

NASA Astrophysics Data System (ADS)

Modelling of geodynamic processes like mantle or core convection has strongly improved over the last two decades thanks to the steady development of numerical codes that tend to incorporate a more and more realistic physics. High-performance parallel computations allow the simulation of complex problems, such as the self-consistent generation of tectonic plates or the formation of planetary magnetic fields. However, the need to perform broad explorations of the parameter space and the large computational demands imposed by the non-linear, multi-scale nature of convection require several simplifications, in the domain geometry as well as in the physical complexity of the problem. A straightforward approach to limit the computational complexity of the simulations is to decrease the total number of degrees of freedom of the problem by reducing either the number of dimensions or the size of the model domain. On the one hand, for a given resolution, a 3D spherical shell clearly needs a much larger number of grid points than a 2D cylindrical shell or a 2D Cartesian box. At the resolutions typically employed to solve mantle convection problems, this difference amounts to at least a factor of a few hundreds. On the other hand, for certain problems, only a relatively small part of the mantle may be of interest, as in the case of the modelling of subduction [1], mid-ocean ridges or transform faults [2]. We adapted the code GAIA [3] to solve the Stokes problem in several different geometries (Cartesian box, cylindrical, spherical and regional-spherical) and dimensions (2D and 3D) and started a benchmark along the lines of [4] to assess the loss of accuracy when using reduced domains instead of a 3D spherical shell [5]. In general, upwellings in Cartesian geometry are rather flat, whereas the spherical geometry changes their shape to more mushroom-like structures. Furthermore, the number of plumes, which is representative of the characteristic wavelength of convection, varies strongly among the geometries used. The geometry and domain size further influence important parameters like the Nusselt number, the average mantle temperature and the root-mean square velocity. One reason for the observed differences is the mantle temperature itself, which depends on the ratio of heat flux into the mantle (at the core-mantle boundary) and loss of heat (at the surface). Since this ratio increases from 3D spherical domain over 2D cylindrical domain towards 2D and 3D box models, the mantle temperature increases as well, leading to a larger Nusselt number and convective velocity. This has not only an influence on the convective plan-form in the mantle, but on surface processes as the occurrence of plate tectonics and outgassing rates, as well.

Noack, L.; Tosi, N.

2012-04-01

455

Tensor Network States and Geometry  

NASA Astrophysics Data System (ADS)

Tensor network states are used to approximate ground states of local Hamiltonians on a lattice in D spatial dimensions. Different types of tensor network states can be seen to generate different geometries. Matrix product states (MPS) in D=1 dimensions, as well as projected entangled pair states (PEPS) in D>1 dimensions, reproduce the D-dimensional physical geometry of the lattice model; in contrast, the multi-scale entanglement renormalization ansatz (MERA) generates a ( D+1)-dimensional holographic geometry. Here we focus on homogeneous tensor networks, where all the tensors in the network are copies of the same tensor, and argue that certain structural properties of the resulting many-body states are preconditioned by the geometry of the tensor network and are therefore largely independent of the choice of variational parameters. Indeed, the asymptotic decay of correlations in homogeneous MPS and MERA for D=1 systems is seen to be determined by the structure of geodesics in the physical and holographic geometries, respectively; whereas the asymptotic scaling of entanglement entropy is seen to always obey a simple boundary law—that is, again in the relevant geometry. This geometrical interpretation offers a simple and unifying framework to understand the structural properties of, and helps clarify the relation between, different tensor network states. In addition, it has recently motivated the branching MERA, a generalization of the MERA capable of reproducing violations of the entropic boundary law in D>1 dimensions.

Evenbly, G.; Vidal, G.

2011-11-01

456

Comparison of Super Resolution Reconstruction Acquisition Geometries for Use in Mouse Phenotyping  

PubMed Central

3D isotropic imaging at high spatial resolution (30–100 microns) is important for comparing mouse phenotypes. 3D imaging at high spatial resolutions is limited by long acquisition times and is not possible in many in vivo settings. Super resolution reconstruction (SRR) is a postprocessing technique that has been proposed to improve spatial resolution in the slice-select direction using multiple 2D multislice acquisitions. Any 2D multislice acquisition can be used for SRR. In this study, the effects of using three different low-resolution acquisition geometries (orthogonal, rotational, and shifted) on SRR images were evaluated and compared to a known standard. Iterative back projection was used for the reconstruction of all three acquisition geometries. The results of the study indicate that super resolution reconstructed images based on orthogonally acquired low-resolution images resulted in reconstructed images with higher SNR and CNR in less acquisition time than those based on rotational and shifted acquisition geometries. However, interpolation artifacts were observed in SRR images based on orthogonal acquisition geometry, particularly when the slice thickness was greater than six times the inplane voxel size. Reconstructions based on rotational geometry appeared smoother than those based on orthogonal geometry, but they required two times longer to acquire than the orthogonal LR images.

Clymer, Bradley D.; Bratasz, Anna; Powell, Kimerly A.

2013-01-01

457

Interferometers as probes of Planckian quantum geometry  

NASA Astrophysics Data System (ADS)

A theory of position of massive bodies is proposed that results in an observable quantum behavior of geometry at the Planck scale, tP. Departures from classical world lines in flat spacetime are described by Planckian noncommuting operators for position in different directions, as defined by interactions with null waves. The resulting evolution of position wave functions in two dimensions displays a new kind of directionally coherent quantum noise of transverse position. The amplitude of the effect in physical units is predicted with no parameters, by equating the number of degrees of freedom of position wave functions on a 2D space-like surface with the entropy density of a black hole event horizon of the same area. In a region of size L, the effect resembles spatially and directionally coherent random transverse shear deformations on time scale ?L/c with typical amplitude ?ctPL. This quantum-geometrical “holographic noise” in position is not describable as fluctuations of a quantized metric, or as any kind of fluctuation, dispersion or propagation effect in quantum fields. In a Michelson interferometer the effect appears as noise that resembles a random Planckian walk of the beam splitter for durations up to the light-crossing time. Signal spectra and correlation functions in interferometers are derived, and predicted to be comparable with the sensitivities of current and planned experiments. It is proposed that nearly colocated Michelson interferometers of laboratory scale, cross-correlated at high frequency, can test the Planckian noise prediction with current technology.

Hogan, Craig J.

2012-03-01

458

Spatial integration in human geometry learning.  

PubMed

In a 2-D computer based search task, human participants were exposed to a compound stimulus containing both geometric and non-geometric information (a rectangle with colored walls) in such a way that a non-geometric cue, C1, was paired with a geometric cue, G1. Previous reinforcement of either kind of cue (geometric and non-geometric) resulted in second order conditioning (SOC) when the participants were tested with the cue that was never paired with reinforcement (Experiment 1). Similarly, if one of the cues was reinforced following the non-reinforced exposure to the compound, a sensory preconditioning (SPC) effect was observed (Experiment 3). These results show that associations can be formed between geometric and non-geometric cues, a finding that is incompatible with the concept of a geometric module impenetrable to non-geometric information. In Experiments 2 and 4, we found evidence for SOC and SPC using exclusively geometric cues, suggesting that the associative learning principles that apply to other domains also rule spatial geometry learning in humans. This research suggests that spatial representations can be enlarged by successively integrating information bits through the linkage of common elements. PMID:21689686

Prados, Jose; Alvarez, Beatriz; Reynolds, Glyn

2011-06-12

459

Rare events in a finite 2D Ising model  

NASA Astrophysics Data System (ADS)

The dynamics of physical systems are always subject to thermal fluctuations or noise. These perturbations will make the stable states of the deterministic part of the dynamical system become only metastable states. When the amplitude of the perturbation is small, the transitions from one metastable state to another are rare events. One such example is the magnetization switching between the two metastable states of 2D Ising model at T < Tc. The 2D Ising model displays two metastable states below the critical temperature Tc. These metastable states are characterized by spontaneous magnetization per spin that tend to m = +/-1 as temperature T ? 0. A finite-size Ising system performs transitions from one metastable phase to another due to thermal fluctuations. Such phase transitions often involve growth or birth of a thermally activated critical nucleus, which is statistically a rare event when the noise is small. It may occur via homogeneous nucleation or heterogeneous nucleation, depending on whether the nucleus is formed in system with periodic boundary condition or with boundary condition of Dirichlet or Neumann type. In this thesis, we study the influences of an applied bulk field and local boundary fields to the critical points (minimums and saddle) of noised-driven phase transitions arising in a finite 2D Ising system in both frameworks of the Ginzburg-Landau theory and lattice spins. We use the string method to numerically allocate the minimum energy path (MEP) and the profile of the energy barrier along it. In the framework of Ginzburg-Landau, we introduce an interface energy functional as a sharp interface limit of the Ginzburg-Landau energy, and compare the numerical results from the string method to the analytical results from this interface energy. In the framework of lattice spin model, we first applied the Transition Path Theory to the system to get the transition rate functional that is suitable for both theoretical and numerical purpose. Then the string method has been used to allocate the minimum free energy path (MFEP). The results from both frameworks are well consistent with each other.

Xuan, Ning

460

Experimental validation of 2D profile photoresist shrinkage model  

NASA Astrophysics Data System (ADS)

For many years, lithographic resolution has been the main obstacle in allowing the pace of transistor densification to meet Moore's Law. For the 32 nm node and beyond, new lithography techniques will be used, including immersion ArF (iArF) lithography and extreme ultraviolet lithography (EUVL). As in the past, these techniques will use new types of photoresists with the capability to print smaller feature widths and pitches. These smaller feature sizes will also require the use of thinner layers of photoresists, such as under 100 nm. In previous papers, we focused on ArF and iArF photoresist shrinkage. We evaluated the magnitude of shrinkage for both R&D and mature resists as a function of chemical formulation, lithographic sensitivity, scanning electron microscope (SEM) beam condition, and feature size. Shrinkage results were determined by the well accepted methodology described in SEMATECH's CD-SEM Unified Specification. In other associated works, we first developed a 1-D model for resist shrinkage for the bottom linewidth and then a 2-D profile model that accounted for shrinkage of all aspects of a trapezoidal profile along a given linescan. A fundamental understanding of the phenomenology of the shrinkage trends was achieved, including how the shrinkage behaves differently for different sized and shaped features. In the 1-D case, calibration of the parameters to describe the photoresist material and the electron beam was all that was required to fit the models to real shrinkage data, as long as the photoresist was thick enough that the beam could not penetrate the entire layer of resist. The later 2-D model included improvements for solving the CD shrinkage in thin photoresists, which is now of great interest for upcoming realistic lithographic processing to explore the change in resist profile with electron dose and to predict the influence of initial resist profile on shrinkage characteristics. The 2-D model also included shrinkage due to both the primary electron beam directly impacting the profile and backscattered electrons from the electron beam impacting the surrounding substrate. This dose from backscattering was shown to be an important component in the resist shrinkage process, such that at lower beam energies, it dominates linewidth shrinkage. In this work, results from a previous paper will be further explored with numerically simulated results and compared to experimental results to validate the model. With these findings, we can demonstrate the state of readiness of these models for predicting the shrinkage characteristics of photoresist measurements and estimating the errors in calculating the original CD from the shrinkage trend.

Bunday, Benjamin; Cordes, Aaron; Self, Andy; Ferry, Lorena; Danilevsky, Alex

2011-03-01