Non-Compact Geometries in 2D Euclidean Quantum Gravity
Gesser, Jens A
2010-01-01
This thesis discusses the worldsheet geometries in the (p,q) minimal model coupled to 2D euclidean Quantum Gravity with particular focus on non-compact geometries. We first calculate the FZZT-FZZT cylinder amplitudes for all pairs of Cardy matter states thereby generalizing the result obtained in arXiv:hep-th/0406030 and discuss the decompositions of the cylinder amplitudes in terms of solutions to the homogeneous Wheeler-DeWitt equation. We then show, that the principal ZZ boundary conditions in Liouville theory can be viewed as effective boundary conditions obtained by integrating out the matter degrees of freedom on the worldsheet. We now consider the (2,2m-1) minimal model coupled to 2D euclidean Quantum Gravity obtained in the scaling limit of dynamical triangulations, in which the mth multi-critical hyper-surface is approached and the conformal background is turned on. We show, that only one concrete realization of matter boundary condition, the (1,1) Cardy boundary condition, is obtained in this scalin...
Non-Compact Geometries in 2D Euclidean Quantum Gravity
Jens A. Gesser
2010-10-24
This thesis discusses the worldsheet geometries in the (p,q) minimal model coupled to 2D euclidean Quantum Gravity with particular focus on non-compact geometries. We first calculate the FZZT-FZZT cylinder amplitudes for all pairs of Cardy matter states thereby generalizing the result obtained in arXiv:hep-th/0406030 and discuss the decompositions of the cylinder amplitudes in terms of solutions to the homogeneous Wheeler-DeWitt equation. We then show, that the principal ZZ boundary conditions in Liouville theory can be viewed as effective boundary conditions obtained by integrating out the matter degrees of freedom on the worldsheet. We now consider the (2,2m-1) minimal model coupled to 2D euclidean Quantum Gravity obtained in the scaling limit of dynamical triangulations, in which the mth multi-critical hyper-surface is approached and the conformal background is turned on. We show, that only one concrete realization of matter boundary condition, the (1,1) Cardy boundary condition, is obtained in this scaling limit. Finally, we study the cylinder amplitude with fixed distance and provide some evidence of a transition from a FZZT-brane to a ZZ-brane on the exit loop in the limit, where the distance approaches infinity, and for particular values of the exit-boundary cosmological constant.
Collective motion of squirmers in a quasi-2D geometry
NASA Astrophysics Data System (ADS)
ZöTtl, Andreas; Stark, Holger
2013-03-01
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.
Facial biometrics based on 2D vector geometry
NASA Astrophysics Data System (ADS)
Malek, Obaidul; Venetsanopoulos, Anastasios; Androutsos, Dimitrios
2014-05-01
The main challenge of facial biometrics is its robustness and ability to adapt to changes in position orientation, facial expression, and illumination effects. This research addresses the predominant deficiencies in this regard and systematically investigates a facial authentication system in the Euclidean domain. In the proposed method, Euclidean geometry in 2D vector space is being constructed for features extraction and the authentication method. In particular, each assigned point of the candidates' biometric features is considered to be a 2D geometrical coordinate in the Euclidean vector space. Algebraic shapes of the extracted candidate features are also computed and compared. The proposed authentication method is being tested on images from the public "Put Face Database". The performance of the proposed method is evaluated based on Correct Recognition (CRR), False Acceptance (FAR), and False Rejection (FRR) rates. The theoretical foundation of the proposed method along with the experimental results are also presented in this paper. The experimental results demonstrate the effectiveness of the proposed method.
Maduri, Rajesh Kumar
2008-02-01
dofs. Pascal's rectangle, Pascal's triangle and Pascal's pyramid provide a systematic selection process for accomplishing this selection process for 2-D quadrilateral, 2-D triangular and 3-D hexahedral geometries respectively. Numerical studies...
Decaying 2D Turbulence in Bounded Domains: Influence of the Geometry
École Normale Supérieure
Decaying 2D Turbulence in Bounded Domains: Influence of the Geometry Kai Schneider1 and Marie Farge to a semiimplicit time discretization with adaptive time stepping. We study the influence of the geometry different geometries, a circle, a square, a triangle and a torus and we show that the geometry plays
3D Geometry Projection from 2D to 3D
Jacobs, David
n n n zzz yyy xxx P Points = y x tsss tsss S 3,22,21,2 3,12,11,1 Some matrix = n n vvv uuu I 21 21 of the points in P. #12;5 First, look at 2D rotation (easier) - n n yyy xxx 21 21 ... cossin sincos coordinates. That is, it's rotated. #12;6 Simple 3D Rotation - n n n zzz yyy xxx 21 21 21 ... 100 0cossin 0
Boundary treatments for 2D elliptic mesh generation in complex geometries
Technology Transfer Automated Retrieval System (TEKTRAN)
This paper presents a boundary treatment method for 2D elliptic mesh generation in complex geometries. Corresponding to Neumann- Dirichlet boundary conditions (sliding boundary conditions), the proposed method aims at achieving orthogonal and smooth nodal distribution along irregular boundaries. In ...
Paris-Sud XI, Université de
GEOMETRY-CONSTRAINED CORONARY ARTERIES MOTION ESTIMATION FROM 2D ANGIOGRAMS - APPLICATION of coronary arteries. It exploits the geometry of acquisition to strongly constrain the problem, thereby of an angiographic exam into right or left artery tree. Index Terms-- Coronary arteries, motion estimation. 1
Part I Euclidean Geometry 1 1 2D Computational Euclidean Geometry 3
Toronto, University of
Geometry 109 11.1 The Projective Line 109 11.2 The Projective Plane 112 11.3 The Projective Space 115 11 for Projective Geometry 119 12.1 The Projective Line 119 12.2 The Projective Plane 122 12.3 The Projective Space 146 14 Oriented Projective Geometry 149 14.1 Double-Sided Projection 149 14.2 The Oriented Projective
Animated Visualization of Causal Relations Through Growing 2D Geometry Niklas Elmqvist
Tsigas, Philippas
Animated Visualization of Causal Relations Through Growing 2D Geometry Niklas Elmqvist Philippas Tsigas Department of Computer Science and Engineering Chalmers University of Technology and G¨oteborg University 412 96 G¨oteborg, Sweden Abstract Causality visualization is an important tool for many sci
Cylindrical 2D ALE simulations of laser interactions with flyer targets
Kurien, Susan
Cylindrical 2D ALE simulations of laser interactions with flyer targets M. Kuchar´ik, J. Limpouch 1 April 2006 We have developed 2D Arbitrary Lagrangian Eulerian (ALE) code in the cylindrical r - z geometry. The ALE method overcomes problems with Lagrangian moving mesh distortion by mesh smoothing
Numerical simulations of annular wire-array z-pinches in (x,y), (r,{theta}), and (r,z) geometries
Marder, B.M.; Sanford, T.W.L.; Allshouse, G.O.
1997-12-01
The Total Immersion PIC (TIP) code has been used in several two-dimensional geometries to understand better the measured dynamics of annular, aluminum wire-array z-pinches. The areas investigated include the formation of the plasma sheath from current-induced individual wire explosions, the effects of wire number and symmetry on the implosion dynamics, and the dependence of the Rayleigh-Taylor instability growth on initial sheath thickness. A qualitative change in the dynamics with increasing wire number was observed, corresponding to a transition between a z-pinch composed of non-merging, self-pinching individual wires, and one characterized by the rapid formation and subsequent implosion of a continuous plasma sheath. A sharp increase in radiated power with increasing wire number has been observed experimentally near this calculated transition. Although two-dimensional codes have correctly simulated observed power pulse durations, there are indications that three dimensional effects are important in understanding the actual mechanism by which these pulse lengths are produced.
Westerly, David C.; Mo, Xiaohu; Tomé, Wolfgang A.; Mackie, Thomas R.; DeLuca, Paul M.
2013-01-01
Purpose: Pencil beam algorithms are commonly used for proton therapy dose calculations. Szymanowski and Oelfke [“Two-dimensional pencil beam scaling: An improved proton dose algorithm for heterogeneous media,” Phys. Med. Biol. 47, 3313–3330 (2002)10.1088/0031-9155/47/18/304] developed a two-dimensional (2D) scaling algorithm which accurately models the radial pencil beam width as a function of depth in heterogeneous slab geometries using a scaled expression for the radial kernel width in water as a function of depth and kinetic energy. However, an assumption made in the derivation of the technique limits its range of validity to cases where the input expression for the radial kernel width in water is derived from a local scattering power model. The goal of this work is to derive a generalized form of 2D pencil beam scaling that is independent of the scattering power model and appropriate for use with any expression for the radial kernel width in water as a function of depth. Methods: Using Fermi-Eyges transport theory, the authors derive an expression for the radial pencil beam width in heterogeneous slab geometries which is independent of the proton scattering power and related quantities. The authors then perform test calculations in homogeneous and heterogeneous slab phantoms using both the original 2D scaling model and the new model with expressions for the radial kernel width in water computed from both local and nonlocal scattering power models, as well as a nonlocal parameterization of Molière scattering theory. In addition to kernel width calculations, dose calculations are also performed for a narrow Gaussian proton beam. Results: Pencil beam width calculations indicate that both 2D scaling formalisms perform well when the radial kernel width in water is derived from a local scattering power model. Computing the radial kernel width from a nonlocal scattering model results in the local 2D scaling formula under-predicting the pencil beam width by as much as 1.4 mm (21%) at the depth of the Bragg peak for a 220 MeV proton beam in homogeneous water. This translates into a 32% dose discrepancy for a 5 mm Gaussian proton beam. Similar trends were observed for calculations made in heterogeneous slab phantoms where it was also noted that errors tend to increase with greater beam penetration. The generalized 2D scaling model performs well in all situations, with a maximum dose error of 0.3% at the Bragg peak in a heterogeneous phantom containing 3 cm of hard bone. Conclusions: The authors have derived a generalized form of 2D pencil beam scaling which is independent of the proton scattering power model and robust to the functional form of the radial kernel width in water used for the calculations. Sample calculations made with this model show excellent agreement with expected values in both homogeneous water and heterogeneous phantoms. PMID:23718585
Geometry dependence of field enhancement in 2D metallic photonic crystals.
Paudel, Hari P; Bayat, Khadijeh; Baroughi, Mahdi Farrokh; May, Stanley; Galipeau, David W
2009-11-23
Geometry dependence of surface plasmon resonance of 2D metallic photonic crystals (PCs) was assessed using rigorous 3D finite difference time domain analysis. PCs of noble metallic rectangular and cylindrical nanopillars in square and triangular lattices on thick noble metal film were simulated for maximum field enhancement. It was found that the period, size and thickness of the nanopillars can be tuned to excite of surface plasmons at desired wavelengths in visible and near-infrared ranges. Maximum electric field enhancement near the nanopillars was found to be greater than 10X. The detail analysis of PCs tuned for 750 nm wavelength showed that thickness of nanopillars was the most sensitive parameter for field enhancement, and triangular lattice PCs had the wider enhancement bandwidth than square lattice PCs. Results showed that these PCs are sensitive with incident angle (theta) but not with polarization angle (phi). PMID:19997464
Large-eddy simulation with complex 2-D geometries using a parallel finite-element/spectral algorithm
NASA Astrophysics Data System (ADS)
Snyder, D. O.; Degrez, G.
2003-04-01
A parallel stabilized finite-element/spectral formulation is presented for incompressible large-eddy simulation with complex 2-D geometries. A unique discretization scheme is developed consisting of a streamline-upwind Petrov-Galerkin/Pressure-Stabilized Petrov-Galerkin (SUPG/PSPG) finite-element discretization in the 2-D plane with a collocated spectral/pseudospectral discretization in the out-of-plane direction. This formulation provides an efficient approach for solving 3-D flows over arbitrary 2-D geometries. Utilizing this discretization and through explicit temporal treatment of the non-linear terms, the system of equations for each Fourier mode is decoupled within each time step. A novel parallelization approach is then taken, where the computational work is partitioned in Fourier space. A validation of the algorithm is presented via comparison of results for flow past a circular cylinder with published values for Re=195, 300, and 3900.
Immersed Boundary Method Based Lattice Boltzmann Method to Simulate 2d and 3d Complex Geometry Flows
NASA Astrophysics Data System (ADS)
Chen, Di-Jia; Lin, Kun-Hao; Lin, Chao-An
In this paper, the lattice Boltzmann method is combined with the immersed boundary technique to simulate complex geometry flows. The complex geometry is represented by Lagrangian markers and forces are exerted at the Lagrangian markers in order to satisfy the prescribed velocity of the boundary. This force at the Lagrangian markers is then distributed to the Eulerian grid by a well-chosen discretized delta function. With the known force field in the Eulerian grid to mimic the boundary, the lattice Boltzmann method is used to compute the flow field where the complex geometry is immersed inside the Cartesian computational domain. Numerical experiments show that the second-order accuracy of the adopted numerical scheme is degraded to 1.8 order. The proposed method is examined by computing decaying vortex, lid driven cavity flow and 2D and 3D flows over asymmetrically placed cylinder. All the numerical results are compatible with the benchmark solutions.
Evaluation of 2D shallow-water model for spillway flow with a complex geometry
Technology Transfer Automated Retrieval System (TEKTRAN)
Although the two-dimensional (2D) shallow water model is formulated based on several assumptions such as hydrostatic pressure distribution and vertical velocity is negligible, as a simple alternative to the complex 3D model, it has been used to compute water flows in which these assumptions may be ...
A distributional approach to the geometry of 2D dislocations at the mesoscale
Lisbon, University of
global 2D strain assumptions relying on the geometric measure theory. Our theory provides the appropriate, single crystals, multi-scale analysis, homogenisation, distri- bution theory, multivalued functions at the mesoscopic scale. In the continuation of previous work the distribution theory is used to represent concen
A distributional approach to the geometry of 2D dislocations at the mesoscale
Lisbon, University of
. The fundamental identity relating the incompatibility tensor to the Frank and Burgers vectors is proved in the 2D dislocation segment has a constant Burgers vector which exhibits additive properties at dislocation junctions and the associated Burgers vector (cf. the survey contributions of KrÂ¨oner 1980, 1990, Kleinert 1989 and Maugin 2003
Effects of Training Method and Gender on Learning 2D\\/3D Geometry
Samsudin Khairulanuar; Abd Rashid Nazre; Omar Khan Sairabanu; Fabil Norasikin
2010-01-01
This article reports the findings of an experimental study involving 36 primary school students (16 girls, 20 boys, Mean age = 9.5 years, age range: 8-10 years) in geometrical understanding of 2D and 3D objects. Students were assigned into two experimental groups and one control group based on a stratified random sampling procedure. The first experimental group trained in an
Reconstruction of 3D Geometry Using 2D Profiles and a Geometric Prior Model
Jyrki Lötjönen; Isabelle E. Magnin; Jukka Nenonen; Toivo Katila
1999-01-01
A method has been developed to reconstruct three-dimensional (3-D) surfaces from two-dimensional (2-D) projection data. It is used to produce individualized boundary element models, consisting of thorax and lung surfaces, for electro- and magnetocardiographic inverse problems. Two orthogonal projections are utilized. A geometrical prior model, built using segmented magnetic resonance images, is deformed according to profiles segmented from projection images.
Collective excitations in a 2D electron system: Canted field geometry
Marinescu, D.C. [Oak Ridge National Lab., TN (United States). Solid State Div.; Quinn, J.J.; Wojs, A. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics
1998-06-01
The authors investigate the charge and spin collective modes induced in a 2D electron gas by a weak electromagnetic perturbation in the presence of a dc magnetic field which makes an angle {theta} with the electron layer. The excitation frequencies are determined within the framework of the Landau-Silin theory of Fermi liquids by solving a semi-classical equation for transport in the self-consistent electromagnetic field associated with particle density fluctuations. The quasiparticle interaction is spin dependent and varies parametrically with the degree of spin polarization. In the long wavelength limit, they obtain analytic results for the frequencies of the collective modes as functions of {theta}.
Determining Transition State Geometries in Liquids Using 2D-IR
Harris, Charles; Cahoon, James F.; Sawyer, Karma R.; Schlegel, Jacob P.; Harris, Charles B.
2007-12-11
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.
Geometry induced potential on a 2D-section of a wormhole: catenoid
Rossen Dandoloff; Avadh Saxena; Bjorn Jensen
2009-12-11
We show that a two dimensional wormhole geometry is equivalent to a catenoid, a minimal surface. We then obtain the curvature induced geometric potential and show that the ground state with zero energy corresponds to a reflectionless potential. By introducing an appropriate coordinate system we also obtain bound states for different angular momentum channels. Our findings can be realized in suitably bent bilayer graphene sheets with a neck or in a honeycomb lattice with an array of dislocations or in nanoscale waveguides in the shape of a catenoid.
NASA Astrophysics Data System (ADS)
Moustafa, Salli; Févotte, François; Lathuilière, Bruno; Plagne, Laurent
2014-06-01
The past few years have been marked by a noticeable increase in the interest in 3D whole-core heterogeneous deterministic neutron transport solvers for reference calculations. Due to the extremely large problem sizes tackled by such solvers, they need to use adapted numerical methods and need to be efficiently implemented to take advantage of the full computing power of modern systems. As for numerical methods, one possible approach consists in iterating over resolutions of 2D and 1D MOC problems by taking advantage of prismatic geometries. The MICADO solver, developed at EDF R&D, is a parallel implementation of such a method in distributed and shared memory systems. However it is currently unable to use SIMD vectorization to leverage the full computing power of modern CPUs. In this paper, we describe our first effort to support vectorization in MICADO, typically targeting Intel© SSE CPUs. Both the 2D and 1D algorithms are vectorized, allowing for high expected speedups for the whole spatial solver. We present benchmark computations, which show nearly optimal speedups for our vectorized implementation on the TAKEDA case.
NASA Astrophysics Data System (ADS)
Ghazanfarian, J.; Abbassi, A.
2012-03-01
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.
NASA Astrophysics Data System (ADS)
Bai, Chao-ying; Li, Xing-wang; Huang, Guo-jiao
2015-02-01
Theoretically, Fresnel volume ray theory is more suitable for handling real seismic propagation problems because the traveltime depends not only on the velocity distribution along a traditional geometric ray but also on the velocity distribution within a vicinal region (referred to as first Fresnel volume, abbreviated as FFV) which embraces the geometric ray. In this study, we used an exact solution to calculate multi-phase FFV rays for both 2-D and 3-D cases and introduced a normalized coefficient to account for different contributions inside the FFV ray on the traveltimes. Furthermore, we draw a new formula to calculate the partial traveltime derivatives with respective to the velocity variations and depth changes of the reflectors and finally present a simultaneous inversion method for updating both velocity field and reflector geometry by using these multi-phase FFV rays for both in 2-D and 3-D cases. Using synthetic data examples, we compare the reconstructions of the velocity field and the reflector geometry using the FFV ray tomographic methods and the traditional ray tomography approaches. The simulated inversion results for both 2-D and 3-D cases show that the FFV ray tomographic method is advantageous over the traditional ray tomography method, especially when the ray density is relatively low. The other advantage for the FFV ray tomography method is that it can capture the coarse velocity structure and reflector geometry by starting with a low-frequency data set and then map the fine velocity structure and the detailed reflector geometry by using a high-frequency data set.
NASA Astrophysics Data System (ADS)
Bai, Chao-ying; Li, Xing-wang; Huang, Guo-jiao
2015-04-01
Theoretically, Fresnel volume ray theory is more suitable for handling real seismic propagation problems because the traveltime depends not only on the velocity distribution along a traditional geometric ray but also on the velocity distribution within a vicinal region (referred to as first Fresnel volume, abbreviated as FFV) which embraces the geometric ray. In this study, we used an exact solution to calculate multi-phase FFV rays for both 2-D and 3-D cases and introduced a normalized coefficient to account for different contributions inside the FFV ray on the traveltimes. Furthermore, we draw a new formula to calculate the partial traveltime derivatives with respective to the velocity variations and depth changes of the reflectors and finally present a simultaneous inversion method for updating both velocity field and reflector geometry by using these multi-phase FFV rays for both in 2-D and 3-D cases. Using synthetic data examples, we compare the reconstructions of the velocity field and the reflector geometry using the FFV ray tomographic methods and the traditional ray tomography approaches. The simulated inversion results for both 2-D and 3-D cases show that the FFV ray tomographic method is advantageous over the traditional ray tomography method, especially when the ray density is relatively low. The other advantage for the FFV ray tomography method is that it can capture the coarse velocity structure and reflector geometry by starting with a low-frequency data set and then map the fine velocity structure and the detailed reflector geometry by using a high-frequency data set.
NASA Astrophysics Data System (ADS)
Igonin, V. V.; Krasovsky, G. B.; Kuratov, S. E.; Lebedev, A. I.; Lebedeva, M. O.; Meshkov, E. E.; Myshkina, I. Yu; Ol'khov, O. V.; Polovnikov, A. A.; Polovnikov, E. A.
2010-12-01
This paper addresses features of hydrodynamic instability growth on shock arrival at a free surface of condensed matter with deterministic initial perturbations. Richtmyer-Meshkov instability growth processes with initial two-dimensional (2D) and 3D perturbations are considered. Experimental diagnostics included pulsed radiography and a two-piston shock-tube technique. It is shown experimentally that the growth of perturbations strongly depends on material compression in the shock tube. In the hydrodynamic approximation, when the shock Mach number is M>1, the growth rate of initial 2D and 3D perturbations is the same. Under weak shock compression conditions (M~1), it may happen that initial 3D perturbations will not grow at all. Our results conflict with theoretical concepts of perturbation growth associated with Richtmyer-Meshkov instability, according to which the growth rate of initial 3D perturbations at the nonlinear stage should always be higher than the growth rate of 2D perturbations for the same a/? ratios. A computational physics model of the process of interest was developed based on LEGAK simulations.
R. Zanino; G. Belgiorno; F. Subba
1998-01-01
Some of the essential features of plasma transport in the tokamak edge with realistic divertor geometry are simulated using\\u000a adaptive finite elements to solve a time-dependent scalar anisotropic conduction-convection-radiation problem. Solutions are\\u000a compared with those obtained on fixed finite element mesh and typically show comparable accuracy at a much lower cost or much\\u000a better accuracy at comparable cost.
NASA Astrophysics Data System (ADS)
Chaudhuri, A.; Sekhar, M.; Descloitres, M.; Godderis, Y.; Ruiz, L.; Braun, J. J.
2013-11-01
Stochastic modelling is a useful way of simulating complex hard-rock aquifers as hydrological properties (permeability, porosity etc.) can be described using random variables with known statistics. However, very few studies have assessed the influence of topological uncertainty (i.e. the variability of thickness of conductive zones in the aquifer), probably because it is not easy to retrieve accurate statistics of the aquifer geometry, especially in hard rock context. In this paper, we assessed the potential of using geophysical surveys to describe the geometry of a hard rock-aquifer in a stochastic modelling framework. The study site was a small experimental watershed in South India, where the aquifer consisted of a clayey to loamy-sandy zone (regolith) underlain by a conductive fissured rock layer (protolith) and the unweathered gneiss (bedrock) at the bottom. The spatial variability of the thickness of the regolith and fissured layers was estimated by electrical resistivity tomography (ERT) profiles, which were performed along a few cross sections in the watershed. For stochastic analysis using Monte Carlo simulation, the generated random layer thickness was made conditional to the available data from the geophysics. In order to simulate steady state flow in the irregular domain with variable geometry, we used an isoparametric finite element method to discretize the flow equation over an unstructured grid with irregular hexahedral elements. The results indicated that the spatial variability of the layer thickness had a significant effect on reducing the simulated effective steady seepage flux and that using the conditional simulations reduced the uncertainty of the simulated seepage flux. As a conclusion, combining information on the aquifer geometry obtained from geophysical surveys with stochastic modelling is a promising methodology to improve the simulation of groundwater flow in complex hard-rock aquifers.
NASA Astrophysics Data System (ADS)
Ahl Laamara, R.; Belhaj, A.; Drissi, L. B.; Saidi, E. H.
2007-08-01
Motivated by studies on 4d black holes and q-deformed 2d Yang-Mills theory, and borrowing ideas from compact geometry of the blowing up of affine ADE singularities, we build a class of local Calabi-Yau threefolds (CY 3) extending the local 2-torus model O(m)?O(-m)?T considered in [C. Gomez, S. Montanez, A comment on quantum distribution functions and the OSV conjecture, hep-th/0608162] to test OSV conjecture. We first study toric realizations of T and then build a toric representation of X using intersections of local Calabi-Yau threefolds O(m)?O(-m-2)?P. We develop the 2d N=2 linear ?-model for this class of toric CY 3s. Then we use these local backgrounds to study partition function of 4d black holes in type IIA string theory and the underlying q-deformed 2d quiver gauge theories. We also make comments on 4d black holes obtained from D-branes wrapping cycles in O(m)?O(-m-2)?B with m=(m,…,m) a k-dim integer vector and B a compact complex one dimension base consisting of the intersection of k 2-spheres Si2 with generic intersection matrix I. We give as well the explicit expression of the q-deformed path integral measure of the partition function of the 2d quiver gauge theory in terms of I. A comment on the link between our analysis and the construction of [N. Caporaso, M. Cirafici, L. Griguolo, S. Pasquetti, D. Seminara, R.J. Szabo, Topological strings, two-dimensional Yang-Mills theory and Chern-Simons theory on torus bundles, hep-th/0609129] is also given.
NASA Astrophysics Data System (ADS)
Schmiedel, T.; Breitkreuz, C.; Görz, I.; Ehling, B.-C.
2015-03-01
Well data and core samples from the Late Paleozoic Halle Volcanic Complex (HVC) have been used to describe the geometry of the rhyolitic porphyritic laccoliths and their margins. The HVC formed between 301 and 292 Ma in the intramontane Saale basin, and it comprises mainly rhyolitic subvolcanic bodies (~300 km3) as well as minor lava flows and volcaniclastic deposits. The major HVC laccolith units display aspect ratios ranging between 0.04 and 0.07, and they are separated by tilted and deformed Carboniferous-Permian host sediments. For the margin of the Landsberg laccolith, a major coarsely porphyritic unit of the HVC, an exceptional data set of 63 wells concentrated in an area of 10 km2 reaching to depth of 710 m exists. It was used to explore the 3D geometry and textures, and to deduce an intrusion model. For a 3D visualization of the Landsberg laccolith margin, Geological Object Computer Aided Design; Paradigm® software (GOCAD) was used. Curve objects have been derived from the intrusion-host contacts. Automated GOCAD® methods for 3D modelling failed. As a result, manual refinement was essential. A major finding of the 3D modelling is the presence of prolate sediment rafts, up to 1,400 m in length and up to 500 m in thickness, surrounded by Landsberg rhyolite. The sedimentary rafts dip away from the laccolith centre. The engulfing laccolith sheets reach thickness of 100-300 m. For other HVC laccolith units (Löbejün, Petersberg, Brachstedt), well data reveal vertical rhyolite/sediment contacts or magma lobes fingering into the host sediments. HVC laccolith contact textures include small-scale shearing of the intruding magma and of the host sediment. In addition, internal shear zones have been detected inside the rhyolite bodies. The present study suggests that the emplacement of successive magma sheets was an important process during laccolith growth in the HVC.
NSDL National Science Digital Library
Rusin, Dave
A short article designed to provide an introduction to geometry, including classical Euclidean geometry and synthetic (non-Euclidean) geometries; analytic geometry; incidence geometries (including projective planes); metric properties (lengths and angles); and combinatorial geometries such as those arising in finite group theory. Many results in this area are basic in either the sense of simple, or useful, or both. History; applications and related fields and subfields; textbooks, reference works, and tutorials; software and tables; other web sites with this focus.
GRAPHICS PROGRAMMING Section B Java 2D
Hill, Gary
GRAPHICS PROGRAMMING Section B Â Java 2D 20 - Graphics2D: Introduction 21 - Graphics2D: Shapes 22 2D: General Path Curves 29 - Graphics 2D: Constructive Area Geometry Gary Hill December 2003 Java 2 Java initially through the Abstract Window Toolkit, which was extended to include swing, shortly
Kolkoori, Sanjeevareddy; Chitti Venkata, Krishnamurthy; Balasubramaniam, Krishnan
2015-01-01
This article presents an analytical approach for simulation of ultrasonic diffracted wave signals from cracks in two-dimensional geometries based on a novel Huygens-Fresnel Diffraction Model (HFDM). The model employs the frequency domain far-field displacement expressions derived by Miller and Pursey in 2D for a line source located on the free surface boundary of a semi-infinite elastic medium. At each frequency in the bandwidth of a pulsed excitation, the complex diffracted field is obtained by summation of displacements due to the unblocked virtual sources located in the section containing a vertical crack. The time-domain diffracted wave signal amplitudes in a general isotropic solid are obtained by standard Fast Fourier Transform (FFT) procedures. The wedge based finite aperture transducer refracted beam profiles were modelled by treating the finite dimension transducer as an array of line sources. The proposed model is able to evaluate back-wall signal amplitude and lateral wave signal amplitude, quantitatively. The model predicted range-dependent diffracted amplitudes from the edge of a bottom surface-breaking crack in the isotropic steel specimen were compared with Geometrical Theory of Diffraction (GTD) results. The good agreement confirms the validity of the HFDM method. The simulated ultrasonic time-of-flight diffraction (TOFD) A-scan signals for surface-breaking crack lengths 2 mm and 4 mm in a 10 mm thick aluminium specimen were compared quantitatively with the experimental results. Finally, important applications of HFDM method to the ultrasonic quantitative non-destructive evaluation are discussed. PMID:25200698
NSDL National Science Digital Library
2014-09-18
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
NSDL National Science Digital Library
Weisstein, Eric W.
Basic geometry resources are always in demand, and educators and students alike will breathe an easy sigh of relief as they are introduced to this set of resources dedicated to this ancient branch of mathematics. Provided by Eric Weisstein at Wolfram Research, the site is simple to navigate and is divided into subtopics that include coordinate geometry, dissection, distance, line geometry, and several dozen other fields of interest. Within each of these subtopics, each topic is addressed in a language that is accessible, accompanied by graphs, charts, and other visual aids that complement the written explanations. Visitors are welcome to leave their own comments on each explanation, and hypertext links lead to other appropriate resources and definitions.
NSDL National Science Digital Library
Ms. Jackson
2008-03-24
We are going to review and sharpen our geometry skills with these fun activities and websites! This game is similar to memory. Practice making making matches with this fun memory game. Match the shape to its definition! Think back to what we have learned and practice identifying geometric shapes and lines by the clues given. This game is timed! Re-arrange the colored pieces given to fit them into the square in ...
NASA Astrophysics Data System (ADS)
Zhou, Yingfang; Helland, Johan Olav; Hatzignatiou, Dimitrios G.
2014-07-01
We present a semi-analytical, combinatorial approach to compute three-phase capillary entry pressures for gas invasion into pore throats with constant cross-sections of arbitrary shapes that are occupied by oil and/or water. For a specific set of three-phase capillary pressures, geometrically allowed gas/oil, oil/water and gas/water arc menisci are determined by moving two circles in opposite directions along the pore/solid boundary for each fluid pair such that the contact angle is defined at the front circular arcs. Intersections of the two circles determine the geometrically allowed arc menisci for each fluid pair. The resulting interfaces are combined systematically to allow for all geometrically possible three-phase configuration changes. The three-phase extension of the Mayer and Stowe - Princen method is adopted to calculate capillary entry pressures for all determined configuration candidates, from which the most favorable gas invasion configuration is determined. The model is validated by comparing computed three-phase capillary entry pressures and corresponding fluid configurations with analytical solutions in idealized triangular star-shaped pores. It is demonstrated that the model accounts for all scenarios that have been analyzed previously in these shapes. Finally, three-phase capillary entry pressures and associated fluid configurations are computed in throat cross-sections extracted from segmented SEM images of Bentheim sandstone. The computed gas/oil capillary entry pressures account for the expected dependence of oil/water capillary pressure in spreading and non-spreading fluid systems at the considered wetting conditions. Because these geometries are irregular and include constrictions, we introduce three-phase displacements that have not been identified previously in pore-network models that are based on idealized pore shapes. However, in the limited number of pore geometries considered in this work, we find that the favorable displacements are not generically different from those already encountered in network models previously, except that the size and shape of oil layers that are surrounded by gas and water are described more realistically. The significance of the results for describing oil connectivity in porous media accurately can only be evaluated by including throats with more complex cross-sections in three-phase pore-network models.
ERIC Educational Resources Information Center
Garber, Judy; Korelitz, Katherine; Samanez-Larkin, Silvia
2012-01-01
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…
NASA Astrophysics Data System (ADS)
Davidson, A.; Tableman, A.; An, W.; Tsung, F. S.; Lu, W.; Vieira, J.; Fonseca, R. A.; Silva, L. O.; Mori, W. B.
2015-01-01
For many plasma physics problems, three-dimensional and kinetic effects are very important. However, such simulations are very computationally intensive. Fortunately, there is a class of problems for which there is nearly azimuthal symmetry and the dominant three-dimensional physics is captured by the inclusion of only a few azimuthal harmonics. Recently, it was proposed [1] to model one such problem, laser wakefield acceleration, by expanding the fields and currents in azimuthal harmonics and truncating the expansion. The complex amplitudes of the fundamental and first harmonic for the fields were solved on an r-z grid and a procedure for calculating the complex current amplitudes for each particle based on its motion in Cartesian geometry was presented using a Marder's correction to maintain the validity of Gauss's law. In this paper, we describe an implementation of this algorithm into OSIRIS using a rigorous charge conserving current deposition method to maintain the validity of Gauss's law. We show that this algorithm is a hybrid method which uses a particles-in-cell description in r-z and a gridless description in ?. We include the ability to keep an arbitrary number of harmonics and higher order particle shapes. Examples for laser wakefield acceleration, plasma wakefield acceleration, and beam loading are also presented and directions for future work are discussed.
Criticism of authority in the writings of Moses Maimonides and Fakhr Al-D?n Al-R?z?.
Langermann, Y Tzvi
2002-01-01
Criticism of authority was a prominent feature of medieval philosophical writing. In this study the critiques of two contemporaneous scholars, Moses Maimonides and Fakhr al-D?n al-R?z?, are compared. Maimonides criticized Hellenistic authorities, mainly Aritotle. However, the starting point for his critique was Aristotle's admission of the limitations of his own inquiries. Maimonides admired Aristotle's questioning of his own conclusions, indeed, his own thought was characterized by constant selfdoubt. Al-R?z? criticized an earlier Muslim scholar, Ibn Sin? (Avicenna), an intellectual giant whose imprint was strongly felt in philosophy and medicine. Al R?z? used his commentaries on a number of Ibn S?n?'s books as a stage for criticizing the master and for arguing for his own, alternative viewpoints. PMID:15045993
Symplectic Geometry Metric geometry
Wolpert, Scott A.
surfaces, metric space geometry, as well as the analytic/algebraic geometry of curvature, characteristicBasics Symplectic Geometry Curvature Metric geometry Random geodesics Weil-Petersson sampler;Basics Symplectic Geometry Curvature Metric geometry Random geodesics Table of contents 1 Introduction
MULTI2D - a computer code for two-dimensional radiation hydrodynamics
NASA Astrophysics Data System (ADS)
Ramis, R.; Meyer-ter-Vehn, J.; Ramírez, J.
2009-06-01
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. Program summaryProgram title: MULTI2D 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.
NASA Astrophysics Data System (ADS)
Bagchi, Arjun; Gopakumar, Rajesh; Mandal, Ipsita; Miwa, Akitsugu
2010-08-01
We make a detailed study of the infinite dimensional Galilean Conformal Algebra (GCA) in the case of two spacetime dimensions. Classically, this algebra is precisely obtained from a contraction of the generators of the relativistic conformal symmetry in 2 d. Here we find quantum mechanical realisations of the (centrally extended) GCA by considering scaling limits of certain 2d CFTs. These parent CFTs are non-unitary and have their left and right central charges become large in magnitude and opposite in sign. We therefore develop, in parallel to the usual machinery for 2 d CFT, many of the tools for the analysis of the quantum mechanical GCA. These include the representation theory based on GCA primaries, Ward identities for their correlation functions and a nonrelativistic Kac table. In particular, the null vectors of the GCA lead to differential equations for the four point function. The solution to these equations in the simplest case is explicitly obtained and checked to be consistent with various requirements.
Diffusion Geometry Diffusion Geometry
Hirn, Matthew
Diffusion Geometry Diffusion Geometry for High Dimensional Data Matthew J. Hirn July 3, 2013 #12;Diffusion Geometry Introduction Embedding of closed curve Figure: Left: A closed, non-self-intersecting curve in 3 dimensions. Right: Its embedding as a circle. #12;Diffusion Geometry Introduction Cartoon
Lectures on 2D gravity and 2D string theory
P. Ginsparg; Gregory Moore
1992-01-01
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
Modeling the longitudinal wall impedance instability in heavy ion beams using an R-Z PIC code
Callahan, D.A.; Langdon, A.B.; Friedman, A.; Grote, D.P. (Lawrence Livermore National Lab., CA (USA)); Haber, I. (Naval Research Lab., Washington, DC (USA))
1991-02-22
The effects of the longitudinal wall impedance instability in a heavy ion beam are of great interest for heavy ion fusion drivers. We are studying this instability using the R-Z thread of the WARP PIC code. We describe the code and our model of the impedance due to the accelerating modules of the induction LINAC as a resistive wall. We present computer simulations which illustrate this instability. 2 refs., 2 figs., 1 tab.
Do Sam KIM; Nam Zin CHO
2003-01-01
The analytic function expansion nodal (AFEN) method has been successfully applied to the rectangular and hexag- onal 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
Do Sam KIM; Nam Zin CHO
2003-01-01
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
Qutb al-D?n Sh?r?z? (1236-1311), Persian polymath physician in the medieval period.
Nadim, Mostafa; Farjam, Mojtaba
2014-05-15
Qutb al-D?n Sh?r?z?, a great physician in the medieval period of the Iranian Islamic age, is also called All?ma (polymath) for his extraordinary expertise in almost all fields of contemporary sciences. The peaceful and cultural environment of his hometown and family contributed to his development despite a time of horror from Mongolian repeated invasions of the Islamic countries. Sh?r?z? never ceased learning and researching and migrated widely in order to find scientists to learn from them. He worked in many centres as a teacher and researcher. He practised medicine and educated students, and his books on other fields of science reflect his comprehensive mastery of most of the basic sciences and the humanities. Sh?r?z??'s social and political roles make him one of the paramount of Iranian elites who contributed to the re-establishment of the Iranian-Islamic civilisation after its destruction by the Mongolians in the thirteenth century. PMID:24833544
2D photonic-crystal optomechanical nanoresonator
K. Makles; T. Antoni; A. G. Kuhn; S. Deléglise; T. Briant; P. F. Cohadon; R. Braive; G. Beaudoin; L. Pinard; C. Michel; V. Dolique; R. Flaminio; G. Cagnoli; I. Robert-Philip; A. Heidmann
2014-10-23
We present the optical optimization of an optomechanical device based on a suspended InP membrane patterned with a 2D near-wavelength grating (NWG) based on a 2D photonic-crystal geometry. We first identify by numerical simulation a set of geometrical parameters providing a reflectivity higher than 99.8 % over a 50-nm span. We then study the limitations induced by the finite value of the optical waist and lateral size of the NWG pattern using different numerical approaches. The NWG grating, pierced in a suspended InP 265 nm-thick membrane, is used to form a compact microcavity involving the suspended nano-membrane as end mirror. The resulting cavity has a waist size smaller than 10 $\\mu$m and a finesse in the 200 range. It is used to probe the Brownian motion of the mechanical modes of the nanomembrane.
2D photonic-crystal optomechanical nanoresonator.
Makles, K; Antoni, T; Kuhn, A G; Deléglise, S; Briant, T; Cohadon, P-F; Braive, R; Beaudoin, G; Pinard, L; Michel, C; Dolique, V; Flaminio, R; Cagnoli, G; Robert-Philip, I; Heidmann, A
2015-01-15
We present the optical optimization of an optomechanical device based on a suspended InP membrane patterned with a 2D near-wavelength grating (NWG) based on a 2D photonic-crystal geometry. We first identify by numerical simulation a set of geometrical parameters providing a reflectivity higher than 99.8% over a 50-nm span. We then study the limitations induced by the finite value of the optical waist and lateral size of the NWG pattern using different numerical approaches. The NWG grating, pierced in a suspended InP 265-nm thick membrane, is used to form a compact microcavity involving the suspended nanomembrane as an end mirror. The resulting cavity has a waist size smaller than 10 ?m and a finesse in the 200 range. It is used to probe the Brownian motion of the mechanical modes of the nanomembrane. PMID:25679837
Spinning geometry = Twisted geometry
NASA Astrophysics Data System (ADS)
Freidel, Laurent; Ziprick, Jonathan
2014-02-01
It is well known that the SU(2)-gauge invariant phase space of loop gravity can be represented in terms of twisted geometries. These are piecewise-linear-flat geometries obtained by gluing together polyhedra, but the resulting geometries are not continuous across the faces. Here we show that this phase space can also be represented by continuous, piecewise-flat three-geometries called spinning geometries. These are composed of metric-flat three-cells glued together consistently. The geometry of each cell and the manner in which they are glued is compatible with the choice of fluxes and holonomies. We first remark that the fluxes provide each edge with an angular momentum. By studying the piecewise-flat geometries which minimize edge lengths, we show that these angular momenta can be literally interpreted as the spin of the edges: the geometries of all edges are necessarily helices. We also show that the compatibility of the gluing maps with the holonomy data results in the same conclusion. This shows that a spinning geometry represents a way to glue together the three-cells of a twisted geometry to form a continuous geometry which represents a point in the loop gravity phase space.
Algebraic Structures and Differential Geometry in 2D String Theory
Edward Witten; Barton Zwiebach
1992-01-01
A careful treatment of closed string BRST cohomology shows that there are\\u000amore discrete states and associated symmetries in $D=2$ string theory than has\\u000abeen recognized hitherto. The full structure, at the $SU(2)$ radius, has a\\u000anatural description in terms of abelian gauge theory on a certain three\\u000adimensional cone $Q$. We describe precisely how symmetry currents are\\u000aconstructed from
Towards enumeration of crystalline frameworks: the 2D hyperbolic approach
NASA Astrophysics Data System (ADS)
Hyde, S. T.; Delgado Friedrichs, O.; Ramsden, S. J.; Robins, V.
2006-07-01
Crystalline frameworks in 3D Euclidean space can be constructed by projecting tilings of 2D hyperbolic space onto three-periodic minimal surfaces, giving surface reticulations. The technique involves Delaney-Dress tiling theory, group theory, differential and non-Euclidean geometry. Preliminary results of this approach, found at http://epinet.anu.edu.au, are discussed and compared with other approaches.
4D and 2D Evaporating Dilatonic Black Holes
Yoav Peleg
1993-03-30
The picture of S-wave scatering from a 4D extremal dilatonic black hole is examined. Classically, a small matter shock wave will form a non-extremal black hole. In the "throat region" the r-t geometry is exactly that of a collapsing 2D black hole. The 4D Hawking radiation (in this classical background) gives the 2D Hawking radiation exactly in the throat region. Inclusion of the back-reaction changes this picture: the 4D solution can then be matched to the 2D one only if the Hawking radiation is very small and only at the beginning of the radiation. We give that 4D solution. When the total radiating energy approaches the energy carried by the shock wave, the 4D picture breaks down. This happens even before an apparent horizon is formed, which suggests that the 4D semi-classical solution is quite different from the 2D one.
What we've learned from 3-D and r,z intense-beam simulations using the WARP code
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
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.
Galax2d: 2D isothermal Euler equations solver
NASA Astrophysics Data System (ADS)
Mulder, Wim
2015-03-01
Galax2d computes the 2D stationary solution of the isothermal Euler equations of gas dynamics in a rotating galaxy with a weak bar. The gravitational potential represents a weak bar and controls the flow. A damped Newton method solves the second-order upwind discretization of the equations for a steady-state solution, using a consistent linearization and a direct solver. The code can be applied as a tool for generating flow models if used on not too fine meshes, up to 256 by 256 cells for half a disk in polar coordinates.
Compatible, energy and symmetry preserving 2D Lagrangian hydrodynamics in rz-cylindrical coordinates
Shashkov, Mikhail [Los Alamos National Laboratory; Wendroff, Burton [Los Alamos National Laboratory; Burton, Donald [Los Alamos National Laboratory; Barlow, A [AWE; Hongbin, Guo [ASU
2009-01-01
We present a new discretization for 2D Lagrangian hydrodynamics in rz geometry (cylindrical coordinates) that is compatible, energy conserving and symmetry preserving. We describe discretization of the basic Lagrangian hydrodynamics equations.
Fast electric field switched 2D-photonic liquid crystals.
Palto, S P; Barnik, M I; Geivandov, A R; Kasyanova, I V; Palto, V S; Shtykov, N M
2015-04-01
We demonstrate field-induced 2D-photonic liquid crystals (LC). The 2D spatially periodic modulation of the LC director field is achieved using a geometry with two crossed interdigitated systems of electrodes located at opposite sides of the LC layer. With a special method of dual-field driving, a very fast switching between different spatially periodic LC director distributions is achieved. The director field distribution and potential use of these photonic crystals for fast switched multidirectional lasing is discussed. PMID:25831306
NIKE2D. Static & Dynamic Response of 2D Solids
Hallquist, J.O. [Lawrence Livermore National Lab., CA (United States)
1992-01-24
NIKE2D is a vectorized, implicit, finite-deformation, large strain, finite-element code for analyzing the response of two-dimensional axisymmetric, plane strain, and plane stress solids. A variety of loading conditions can be handled including traction boundary conditions, displacement boundary conditions, concentrated nodal point loads, body force loads due to base accelerations, and body force loads due to spinning. Slide-lines with interface friction are available. Elastic, orthotropic-elastic, elastic-plastic, soil and crushable foam, thermo-elastic-plastic, linear viscoelastic thermo-orthotropic elastic, elastic-creep, and strain rate dependent material models are implemented. Nearly incompressible behavior that arises in plasticity problems and elasticity problems with Poisson`s ratio approaching 0.5 is accounted for in the element formulation to preclude mesh lock-ups and associated anomalous stress states. FISSLE (Fast Implicit Solver for Systems of Linear Equations), a set of subroutines used by NIKE2D, is included.
NIKE2D. Static & Dynamic Response of 2D Solids
Hallquist, J.O. [Lawrence Livermore National Lab., CA (United States)
1992-01-24
NIKE2D is a vectorized, implicit, finite-deformation, large strain, finite-element code for analyzing the response of two-dimensional axisymmetric,plane strain, and plane stress solids. A variety of loading conditions can be handled including traction boundary conditions, displacement boundary conditions, concentrated nodal point loads, body force loads due to base accelerations, and body force loads due to spinning. Slide-lines with interface friction are available. Elastic, orthotropic-elastic, elastic-plastic, soil and crushable foam, thermo-elastic-plastic, linear viscoelastic thermo-orthotropic elastic, elastic-creep, and strain rate dependent material models are implemented. Nearly incompressible behavior that arises in plasticity problems and elasticity problems with Poisson`s ratio approaching 0.5 is accounted for in the element formulation to preclude mesh lock-ups and associated anomalous stress states. FISSLE (Fast Implicit Solver for Systems of Linear Equations), a set of subroutines used by NIKE2D, is included.
Goldman, William
The Geometry of 2 Ã? 2 Matrices William M. Goldman Algebraicizing geometry Euclidean geometry William M. Goldman Algebraicizing geometry Euclidean geometry Spherical geometry Triangle tilings geometry Euclidean geometry Spherical geometry Triangle tilings Stereographic projection Hyperbolic
Pythagoras' Theorem on a 2D-Lattice from a \\
Jian Dai; Xing-Chang Song
2001-01-01
One of the key ingredients of A. Connes' noncommutative geometry is a\\u000ageneralized Dirac operator which induces a metric(Connes' distance) on the\\u000astate space. We generalize such a Dirac operator devised by A. Dimakis et al,\\u000awhose Connes' distance recovers the linear distance on a 1D lattice, into 2D\\u000alattice. This Dirac operator being \\
Conformal Geometry and the Universe By Anthony Lasenby
Cambridge, University of
of the transfer of a result from 2d non-Euclidean geometry to 4d de Sitter space (the Origin Lemma in the Poincar histories. Keywords: conformal geometry, geometric algebra, non-Euclidean geometry, de Sitter space to the case of non-Euclidean geometries, both spherical and hyperbolic, and in Lasenby & Lasenby (2003) have
Koshelkin, Andrey V. [Moscow Institute for Physics and Engineering, Russia] [Moscow Institute for Physics and Engineering, Russia; Wong, Cheuk-Yin [ORNL] [ORNL
2012-01-01
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.
JAMES W. CANNON; WILLIAM J. FLOYD; RICHARD KENYON; WALTER R. PARRY
Non-Euclidean, or hyperbolic, geometry was created in the first half of the nine- teenth century in the midst of attempts to understand Euclid's axiomatic basis for geometry. Einstein and Minkowski found in non-Euclidean geometry a geometric basis for the understanding of physical time and space. In the early part of the twentieth century every serious student of mathematics and physics
A Spot Segmentation Approach for 2D Gel Electrophoresis Images Based on 2D Histograms
Athens, University of
A Spot Segmentation Approach for 2D Gel Electrophoresis Images Based on 2D Histograms Eleni@bioacademy.gr Abstract Spot-Segmentation, an essential stage of processing 2D gel electrophoresis images, remains approach to spot segmentation in 2D gel electrophoresis images. The proposed approach is based on 2D
Ultrafast 2D IR Vibrational Echo Spectroscopy
Fayer, Michael D.
Ultrafast 2D IR Vibrational Echo Spectroscopy JUNRONG ZHENG, KYUNGWON KWAK, AND M. D. FAYER The experimental technique and applications of ultrafast two- dimensional infrared (2D IR) vibrational echo systems. The form and time evolution of the 2D IR spectrum permits examination of processes that cannot
NSDL National Science Digital Library
2010-01-01
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.
Michael Deering
1995-01-01
This paper introduces the concept of Geometry Compression, al- lowing 3D triangle data to be represented with a factor of 6 to 10 times fewer bits than conventional techniques, with only slight loss- es in object quality. The technique is amenable to rapid decompres- sion in both software and hardware implementations; if 3D render- ing hardware contains a geometry decompression
Dynamic unfolding of multilayers: 2D numerical approach and application to turbidites in SW Portugal
S. M. Lechmann; S. M. Schmalholz; J.-P. Burg; F. O. Marques
2010-01-01
Numerical algorithms for two-dimensional (2D) ductile multilayer folding are used (1) to unfold synthetically generated multilayer folds and natural multilayer folds in turbidites on the SW coast of Portugal and (2) to test how 2D ductile multilayer folding may generate collapsed hinges. A series of dynamic retro-deformation experiments with different viscosity ratios, rheological flow laws, boundary conditions and initial geometries
On 2D N = (4,4) superspace supergravity
NASA Astrophysics Data System (ADS)
Tartaglino-Mazzucchelli, Gabriele
2011-05-01
We review some recent results obtained in studying superspa.ee formulations of 2D N = (4,4) matter-coupled supergravity. For a superspace geometry described by the minimal supergravity multiplet, we first describe how to reduce to components the chiral integral by using "ectoplasm" superform techniques as in arXiv:0907.5264 and then we review the bi-projective superspace formalism introduced in arXiv:0911.2546. After that, we elaborate on the curved bi-projective formalism providing a new result: the solution of the covariant type-I twisted multiplet constraints in terms of a weight-(-1, -1) bi-projective superfield.
Eldar, Yonina
COMPRESSED 3D ULTRASOUND IMAGING WITH 2D ARRAYS Michael Birk*, Amir Burshtein*, Tanya Chernyakova's Nyquist rate, which greatly increases the volume of data that must be processed. In 3D ultrasound imaging extend previous work on frequency domain beamforming for 2D ultrasound imaging to the geometry imposed
NKG2D signaling in cancer immunosurveillance.
López-Soto, Alejandro; Huergo-Zapico, Leticia; Acebes-Huerta, Andrea; Villa-Alvarez, Mónica; Gonzalez, Segundo
2015-04-15
The immune system is able to detect and eliminate transformed cells. The activating receptor NKG2D is particularly relevant for cancer immunosurveillance. NKG2D ligand expression renders tumor cells more susceptible to be killed by NK and T cells, and correlates with the clinical outcome of the disease. However, tumors develop mechanisms to overcome the NKG2D-mediated immune response, which has been associated with poor prognosis and impairment of the clinical benefits of immunotherapy in many human cancers. The highly specific pattern of expression displayed by the NKG2D ligands, mainly confined to tumor cells, together with the strong immune response triggered by this receptor clearly supports the idea that the NKG2D-mediated pathway may be a powerful target for the treatment of cancer. This review draws together the most recent discoveries concerning the biology of the NKG2D signaling and their therapeutic relevance in the context of cancer. PMID:24615398
Purcaru, Elena
2012-01-01
The paper presents a solution for endcoding/decoding DNA information in 2D barcodes. First part focuses on the existing techniques and symbologies in 2D barcodes field. The 2D barcode PDF417 is presented as starting point. The adaptations and optimizations on PDF417 and on DataMatrix lead to the solution - DNA2DBC - DeoxyriboNucleic Acid Two Dimensional Barcode. The second part shows the DNA2DBC encoding/decoding process step by step. In conclusions are enumerated the most important features of 2D barcode implementation for DNA.
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.
Lajos Tamássy
\\u000a In the thirties of the 19th century János Bolyai and Nikolai Ivanovi? Lobacevskii created the hyperbolic geometry. Thus they proved that not only the\\u000a Euclidean but also other geometries may exist. Concerning its geometrical importance, this discovery can be compared to the\\u000a change which replaced the Ptolemaic geocentric concept of astronomy by the heliocentric point of view of Copernicus. Hyperbolic
Geometry of Generalized Depolarizing Channels
Christian K. Burrell
2009-09-10
A generalized depolarizing channel acts on an N-dimensional quantum system to compress the ``Bloch ball'' in N^2-1 directions; it has a corresponding compression vector. We investigate the geometry of these compression vectors and prove a conjecture of Dixit and Sudarshan [1], namely that when N=2^d (i.e. the system consists of d qubits) and we work in the Pauli basis then the set of all compression vectors forms a simplex. We extend this result by investigating the geometry in other bases; in particular we find precisely when the set of all compression vectors forms a simplex.
Image Representation Using 2D Gabor Wavelets
Tai Sing Lee
1996-01-01
This paper extends to two dimensions the frame criterion developed by Daubechies for one-dimensional wavelets, and itcomputes the frame bounds for the particular case of 2D Gabor wavelets. Completeness criteria for 2D Gabor imagerepresentations are important because of their increasing role in many computer vision applications and also in modeling biologicalvision, since recent neurophysiological evidence from the visual cortex of
BRS analysis of 2D gravity models
NASA Astrophysics Data System (ADS)
Yang, Z.
1990-06-01
Using the original BRS approach we determine, from the requirement of diffeomorphism invariance, the DDK action of 2D quantum gravity in conformal gauge. The necessity to take into account quantum corrections due to Liouville modes is pointed out. A quantum effective action for a pure 2D gravity with the classical action ?d 2x?- gNR is also determined.
Annotated Bibliography of EDGE2D Use
J.D. Strachan and G. Corrigan
2005-06-24
This annotated bibliography is intended to help EDGE2D users, and particularly new users, find existing published literature that has used EDGE2D. Our idea is that a person can find existing studies which may relate to his intended use, as well as gain ideas about other possible applications by scanning the attached tables.
1-D & 2-D Scans Epistasis Plots
Yandell, Brian S.
Outline Overview 1-D & 2-D Scans Anova Fit Epistasis Plots Conclusion Prototype QTL Strategy-D Scans Anova Fit Epistasis Plots Conclusion Overview Initialization 1-D & 2-D Scans Anova Fit Epistasis Plots Conclusion Brian S. Yandell, W. Whipple Neely, Nengjun Yi Prototype QTL Strategy: Phenotype
Staring 2-D hadamard transform spectral imager
Gentry, Stephen M. (Albuquerque, NM); Wehlburg, Christine M. (Albuquerque, NM); Wehlburg, Joseph C. (Albuquerque, NM); Smith, Mark W. (Albuquerque, NM); Smith, Jody L. (Albuquerque, NM)
2006-02-07
A staring imaging system inputs a 2D spatial image containing multi-frequency spectral information. This image is encoded in one dimension of the image with a cyclic Hadamarid S-matrix. The resulting image is detecting with a spatial 2D detector; and a computer applies a Hadamard transform to recover the encoded image.
2D conglomerate crystallization of heptahelicene.
Seibel, Johannes; Zoppi, Laura; Ernst, Karl-Heinz
2014-08-14
Two-dimensional (2D) nucleation and crystallization of the helical aromatic hydrocarbon heptahelicene on the single crystalline copper(100) surface has been studied with scanning tunnelling microscopy. In contrast to previously observed racemic 2D crystals on Cu(111), separation into homochiral domains is observed for Cu(100). PMID:24968343
Algebra = Geometry Sandor Kovacs
Kovács, Sándor
Algebra = Geometry S´andor Kov´acs University of Washington #12;Motto "To me, algebraic geometry is algebra with a kick" Solomon Lefschetz #12;Geometry Geometry = Space + Functions #12;Geometry Geometry = Space + Functions Type of function Type of Geometry #12;Geometry Geometry = Space + Functions Type
Design Application Translates 2-D Graphics to 3-D Surfaces
NASA Technical Reports Server (NTRS)
2007-01-01
Fabric Images Inc., specializing in the printing and manufacturing of fabric tension architecture for the retail, museum, and exhibit/tradeshow communities, designed software to translate 2-D graphics for 3-D surfaces prior to print production. Fabric Images' fabric-flattening design process models a 3-D surface based on computer-aided design (CAD) specifications. The surface geometry of the model is used to form a 2-D template, similar to a flattening process developed by NASA's Glenn Research Center. This template or pattern is then applied in the development of a 2-D graphic layout. Benefits of this process include 11.5 percent time savings per project, less material wasted, and the ability to improve upon graphic techniques and offer new design services. Partners include Exhibitgroup/Giltspur (end-user client: TAC Air, a division of Truman Arnold Companies Inc.), Jack Morton Worldwide (end-user client: Nickelodeon), as well as 3D Exhibits Inc., and MG Design Associates Corp.
Geometry Dependence of Stellarator Turbulence
H.E. Mynick, P. Xanthopoulos and A.H. Boozer
2009-08-10
Using the nonlinear gyrokinetic code package GENE/GIST, we study the turbulent transport in a broad family of stellarator designs, to understand the geometry-dependence of the microturbulence. By using a set of flux tubes on a given flux surface, we construct a picture of the 2D structure of the microturbulence over that surface, and relate this to relevant geometric quantities, such as the curvature, local shear, and effective potential in the Schrodinger-like equation governing linear drift modes.
2D and 3D Method of Characteristic Tools for Complex Nozzle Development
NASA Technical Reports Server (NTRS)
Rice, Tharen
2003-01-01
This report details the development of a 2D and 3D Method of Characteristic (MOC) tool for the design of complex nozzle geometries. These tools are GUI driven and can be run on most Windows-based platforms. The report provides a user's manual for these tools as well as explains the mathematical algorithms used in the MOC solutions.
NETGEN -An Advancing Front 2D/3D-Mesh Generator Based on Abstract Rules
Schoeberl, Joachim
NETGEN - An Advancing Front 2D/3D-Mesh Generator Based on Abstract Rules Joachim Schoberl Abstract In this paper, the algorithms of the automatic mesh generator NETGEN are described. The domain is provided by a Constructive Solid Geometry (CSG). The whole task of 3D mesh generation splits into four subproblems of special
High-Quality 2D Metal-Organic Coordination Network Providing Giant Cavities within Mesoscale Domains
Brune, Harald
High-Quality 2D Metal-Organic Coordination Network Providing Giant Cavities within Mesoscale of porous structures providing spaces with a well-defined geometry and chemical environment.1,2 However-directed assembly of nanomeshes, allowed for atomic resolution imaging of the atomic silver lattice therein. Thus we
Green’s function measurements of force transmission in 2D granular materials
Junfei Geng; G. Reydellet; E. Clément; R. P. Behringer
2003-01-01
We describe experiments that probe the response to a point force of 2D granular systems under a variety of conditions. Using photoelastic particles to determine forces at the grain scale, we obtain ensembles of responses for the following particle types, packing geometries and conditions: monodisperse ordered hexagonal packings of disks, bidisperse packings of disks with different amounts of disorder, disks
Particle shape and the strengthening transition in 2D granular shearing
Daniel W. Howell; R. P. Behringer
1999-01-01
We show experimentally that a slowly sheared 2D granular material undergoes a transition as the packing fraction gamma is increased through a critical value, gammac ~= 0.777 for disks and gammac ~= 0.725 for pentagons. The experiment consists of ~ 3000 photoelastic disks or pentagons confined to a plane Couette geometry by Plexiglas sheets, an inner disk, and an outer
NSDL National Science Digital Library
Rusin, David J., 1957-
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.
Choi, Suhyoung
Â Projective geometry Â Conformal geometry: Poincare extensions Â Hyperbolic geometry Lorentz group Geometry.4 Projective geometry Projective geometry Â· Projective geometry was first considered from fine art. Â· Desargues: http://www.math.poly.edu/courses/ projective_geometry/ Â· and http
Infrared spectra of the Nesbnd C2D4 and Arsbnd C2D4 complexes
NASA Astrophysics Data System (ADS)
Rezaei, M.; Michaelian, K. H.; McKellar, A. R. W.; Moazzen-Ahmadi, N.
2013-07-01
Spectra of Nesbnd C2D4 and Arsbnd C2D4 are studied in the ?11 fundamental band region of C2D4 (?2200 cm-1) using a tuneable quantum cascade laser to probe a pulsed supersonic slit jet expansion. The spectra are those of perpendicular bands of near-prolate asymmetric rotors, but with a doubling of transitions due to tunneling. These tunneling splittings are due to hindered internal rotation of C2D4 around its Csbnd C axis, and are more prominent for Nesbnd C2D4 than for Arsbnd C2D4. The analysis yields the first direct measurement of the A rotational constants for these complexes, and shows that the vibrational shifts are very small (<0.3 cm-1). Attempts to observe the spectrum of Hesbnd C2D4 were not successful.
Brittle damage models in DYNA2D
Faux, D.R.
1997-09-01
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.
Ginsparg, P.
1991-12-31
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.
1991-01-01
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.
Finite Heat conduction in 2D Lattices
Lei Yang; Yang Kongqing
2001-07-30
This paper gives a 2D hamonic lattices model with missing bond defects, when the capacity ratio of defects is enough large, the temperature gradient can be formed and the finite heat conduction is found in the model. The defects in the 2D harmonic lattices impede the energy carriers free propagation, by another words, the mean free paths of the energy carrier are relatively short. The microscopic dynamics leads to the finite conduction in the model.
Scaling relations for 2 D percolation
Harry Kesten
1987-01-01
We prove that the relations 2D-percolation hold for the usual critical exponents for 2D-percolation, provided the exponents d andv exist. Even without the last assumption various relations (inequalities) are obtained for the singular behavior near the critical point of the correlation length, the percolation probability, and the average cluster size. We show that in our models the above critical exponents
2d index and surface operators
NASA Astrophysics Data System (ADS)
Gadde, Abhijit; Gukov, Sergei
2014-03-01
In this paper we compute the superconformal index of 2d (2, 2) supersymmetric gauge theories. The 2d superconformal index, a.k.a. flavored elliptic genus, is computed by a unitary matrix integral much like the matrix integral that computes the 4d superconformal index. We compute the 2d index explicitly for a number of examples. In the case of abelian gauge theories we see that the index is invariant under flop transition and under CY-LG correspondence. The index also provides a powerful check of the Seiberg-type duality for non-abelian gauge theories discovered by Hori and Tong. In the later half of the paper, we study half-BPS surface operators in = 2 super-conformal gauge theories. They are engineered by coupling the 2d (2, 2) supersymmetric gauge theory living on the support of the surface operator to the 4d = 2 theory, so that different realizations of the same surface operator with a given Levi type are related by a 2d analogue of the Seiberg duality. The index of this coupled system is computed by using the tools developed in the first half of the paper. The superconformal index in the presence of surface defect is expected to be invariant under generalized S-duality. We demonstrate that it is indeed the case. In doing so the Seiberg-type duality of the 2d theory plays an important role.
GMC Collisions as Triggers of Star Formation. I. Parameter Space Exploration with 2D Simulations
Wu, Benjamin; Tan, Jonathan C; Bruderer, Simon
2015-01-01
We utilize magnetohydrodynamic (MHD) simulations to develop a numerical model for GMC-GMC collisions between nearly magnetically critical clouds. The goal is to determine if, and under what circumstances, cloud collisions can cause pre-existing magnetically subcritical clumps to become supercritical and undergo gravitational collapse. We first develop and implement new photodissociation region (PDR) based heating and cooling functions that span the atomic to molecular transition, creating a multiphase ISM and allowing modeling of non-equilibrium temperature structures. Then in 2D and with ideal MHD, we explore a wide parameter space of magnetic field strength, magnetic field geometry, collision velocity, and impact parameter, and compare isolated versus colliding clouds. We find factors of ~2-3 increase in mean clump density from typical collisions, with strong dependence on collision velocity and magnetic field strength, but ultimately limited by flux-freezing in 2D geometries. For geometries enabling flow a...
NSDL National Science Digital Library
Ms. Yost
2009-10-26
Let's practice some geometry skills. First, try to feed Billy Bug all the grubs in Billy Bug: Quadrant I. Just click on "Start," move Billy Bug with the arrow keys on the screen, and click "Feed" when you're at the coordinate where the grub is located. If you're up for a challenge, try Billy Bug: All Quadrants! Then, in Robo Packer, you will ...
TOPAZ2D heat transfer code users manual and thermal property data base
Shapiro, A.B.; Edwards, A.L.
1990-05-01
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.
'Graphenization' of 2D simple monatomic liquids.
Hoang, Vo Van
2014-05-21
We present molecular dynamics (MD) simulations of the formation of 2D materials with a honeycomb structure from 2D simple monatomic liquids with honeycomb interaction potential (Rechtsman et al 2005 Phys. Rev. Lett. 95 228301). Models are observed by cooling from the melt at various cooling rates. Thermodynamics of the phase transitions is analyzed in detail. Depending on the cooling rate, amorphous or crystalline honeycomb structures have been found. Structural properties of the crystalline honeycomb structure are studied via radial distribution function (RDF), coordination number and ring distribution, including 2D visualization of the atomic configurations. We find evidence for the existence of polycrystalline honeycomb structures and new structural defects, not previously reported. The atomic mechanism that forms the solid phase of a honeycomb structure from the liquid state has been analyzed by monitoring the spatio-temporal arrangement of atoms in 6-fold rings and/or atoms with the coordination number [Formula: see text], occurring upon cooling from the melt. Since knowledge of how real 2D solids with honeycomb structures form from the vapor or liquid phase is still completely lacking, our simulations highlight the situation and give a deeper understanding of the structure and thermodynamics of real 2D materials such as graphene, silicene, germanene, etc. PMID:24769527
Premixed Flame Dynamics in Narrow 2D Channels
Ayoobi, Mohsen
2015-01-01
Premixed flames propagating within small channels show complex combustion phenomena that differ from flame propagation at conventional scales. Available experimental and numerical studies have documented stationary/non-stationary and/or asymmetric modes that depend on properties of the incoming reactant flow as well as channel geometry and wall temperatures. The present work seeks to illuminate mechanisms leading to symmetry-breaking and limit cycle behavior that are fundamental to these combustion modes. Specifically, four cases of lean premixed methane/air combustion -- two equivalence ratios (0.53 and 0.7) and two channel widths (2 and 5mm) -- are investigated in a 2D configuration with constant channel length and bulk inlet velocity, where numerical simulations are performed using detailed chemistry. External wall heating is simulated by imposing a linear temperature gradient as a boundary condition on both walls. In the 2mm-channel, both equivalence ratios produce flames that stabilize with symmetric fla...
Interpretive 2-D treatment of scrape-off-layer plasmas
Umansky, M.; Allen, A.; Daughton, W. [MIT Plasma Fusion Center, Cambridge, MA (United States)] [and others
1996-12-31
The width of the scrape-off-layer in a tokamak is determined by cross field transport. In Alcator C-mod the plasma parameters in the scrape-off-layer are measured at upstream and divertor plate locations. We solve a 2-D scrape-off-layer heat conduction equation in the flux geometry (as determined by EFIT) of the C-mod experiment. Bolometric measurements are utilized for the radiative loss term. We use the end wall probe measurements of electron temperature as a boundary condition and the fast scanning probe measurements of upstream temperature are treated as constraints to determine the cross field transport and thermal conductivity. Results are compared with 1-D onion-skin-model predictions.
Grid generation for general 2-D regions using hyperbolic equations
NASA Technical Reports Server (NTRS)
Cordova, Jeffrey Q.; Barth, Timothy J.
1988-01-01
A method for applying a hyperbolic grid generation scheme to the construction of meshes in general 2-D regions has been developed. This approach, which follows the theory developed by Steger and Chaussee (1980) and the algorithm outlined by Kinsey and Barth (1984), is based on improving local grid control. This is accomplished by adding an angle control source term to the equations and using a new algorithm for computing the volume source term. These modifications lead to superior methods for fixing the 'local' problems of hyperbolic grid generation, namely, propagation of initial discontinuities and formation of grid shocks (crossing grid lines). More importantly, a method for solving the global problem of constraining the grid with more than one boundary (internal grid generation) has been developed. These algorithms have been implemented in an interactive grid generation program and the results for several geometries are presented and discussed.
2D microwave imaging reflectometer electronics
NASA Astrophysics Data System (ADS)
Spear, A. G.; Domier, C. W.; Hu, X.; Muscatello, C. M.; Ren, X.; Tobias, B. J.; Luhmann, N. C.
2014-11-01
A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program.
2D microwave imaging reflectometer electronics.
Spear, A G; Domier, C W; Hu, X; Muscatello, C M; Ren, X; Tobias, B J; Luhmann, N C
2014-11-01
A 2D microwave imaging reflectometer system has been developed to visualize electron density fluctuations on the DIII-D tokamak. Simultaneously illuminated at four probe frequencies, large aperture optics image reflections from four density-dependent cutoff surfaces in the plasma over an extended region of the DIII-D plasma. Localized density fluctuations in the vicinity of the plasma cutoff surfaces modulate the plasma reflections, yielding a 2D image of electron density fluctuations. Details are presented of the receiver down conversion electronics that generate the in-phase (I) and quadrature (Q) reflectometer signals from which 2D density fluctuation data are obtained. Also presented are details on the control system and backplane used to manage the electronics as well as an introduction to the computer based control program. PMID:25430247
2D Models for Dust-driven AGB Star Winds
Peter Woitke
2006-02-16
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 most simple case without stellar pulsation (hydrostatic inner boundary condition) these models reveal a more complex picture of the dust formation and wind acceleration as compared to earlier published spherically symmetric (1D) models. The so-called exterior $\\kappa$-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 result 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.
The 2D lingual appliance system.
Cacciafesta, Vittorio
2013-09-01
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
Inkjet printing of 2D layered materials.
Li, Jiantong; Lemme, Max C; Östling, Mikael
2014-11-10
Inkjet printing of 2D layered materials, such as graphene and MoS2, has attracted great interests for emerging electronics. However, incompatible rheology, low concentration, severe aggregation and toxicity of solvents constitute critical challenges which hamper the manufacturing efficiency and product quality. Here, we introduce a simple and general technology concept (distillation-assisted solvent exchange) to efficiently overcome these challenges. By implementing the concept, we have demonstrated excellent jetting performance, ideal printing patterns and a variety of promising applications for inkjet printing of 2D layered materials. PMID:25169938
Harmonic generation in 2D layered materials
NASA Astrophysics Data System (ADS)
Janisch, Corey; Ma, Ding; Mehta, Nikhil; Laura-Elias, Ana; Perea-Lopez, Nestor; Terrones, Mauricio; Liu, Zhiwen
2014-09-01
Two-Dimensional (2D) layered materials have garnered interest due to their novel optical and electronic properties. In this work, we investigate Second Harmonic Generation (SHG) in Tungsten Disulfide (WS2) monolayers grown on SiO2/Si substrates and suspended on a transmission electron microscopy grid; we find an unusually large second order susceptibility, which is nearly three orders of magnitude larger than common nonlinear crystals. We have also developed a Green's function based formalism to model the harmonic generation from a 2D layer .
Alain Connes
1994-01-01
Through algebraic geometry we became familiar with the correspondence between geometrical spaces and commutative algebra.\\u000a The aim of this talk is to show an analogous correspondence, in the domain of real analysis, between geometrical spaces and\\u000a algebras of functional analysis, going beyond the commutative case. This theory is based on three essential points:\\u000a \\u000a \\u000a 1. \\u000a \\u000a The existence of many examples of
Quasar Clustering and Spacetime Geometry
Piotr A. Popowski; David H. Weinberg; Barbara S. Ryden; Patrick S. Osmer
1997-07-15
The non-Euclidean geometry of spacetime induces an anisotropy in the apparent correlation function of high-redshift quasars. This effect can constrain the cosmological constant \\Lambda independent of any assumptions about evolution of luminosities, sizes, or clustering. We examine the prospects for distinguishing between low-density (\\Omega_0=0.1-0.4) cosmological models with flat and open space geometry using the quasar samples anticipated from the 2dF and Sloan redshift surveys. We show that even these large quasar surveys are likely to reside in the "sparse sampling" regime, so that measurement errors in the correlation function obey Poisson statistics. As a result: (a) one can devise a simple maximum-likelihood scheme for estimating clustering parameters, (b) one can generate Monte Carlo realizations of correlation function measurements without creating artificial quasar distributions, and (c) for fixed quasar number, a deeper survey over a smaller area has greater statistical power than a shallow, large-area survey. Adopting recent (quite uncertain) estimates of the quasar correlation length, we find that the 2dF and Sloan samples can provide clear discrimination between flat and open geometries for \\Omega <= 0.2 but only marginal discrimination for \\Omega = 0.4. Clear discrimination is possible for \\Omega = 0.4 if the true quasar correlation length is a factor of two larger, and a high-density survey of 30,000 quasars in 200 square degrees would provide clear discrimination even for the lower correlation length.
Double two-dimensional correlation analysis - 2D correlation of 2D spectra
NASA Astrophysics Data System (ADS)
Noda, Isao
2010-06-01
2D correlation analysis of 2D correlation spectra, i.e., double 2D correlation analysis, is carried out by a series of simple matrix multiplication operations. A new class of correlation spectra with higher selectivity and spectral resolution are generated. Quadrature 2D correlation enabled by the proper rescaling of double 2D correlation is especially useful for the analysis of the contravariant portion of spectral signals, which are 90 deg out of phase with the rest of data. The utility of double 2D correlation is most clearly demonstrated when it is applied to hetero-spectral or hetero-mode correlation analysis. Double hetero-correlation generates highly selective 2D spectra based on a portion of spectra which is projected onto a space spanned by other spectra or different spectral region. Illustrative examples are provided with Raman spectral monitoring of an emulsion polymerization process and a solution mixture undergoing compositional changes to show how double 2D correlation can be utilized.
A. Nicolaidis; V. Kiosses
2012-01-03
It has been proposed that quantum mechanics and string theory share a common inner syntax, the relational logic of C. S. Peirce. Along this line of thought we consider the relations represented by spinors. Spinor composition leads to the emergence of Minkowski spacetime. Inversely the Minkowski spacetime is istantiated by the Weyl spinors, while the merge of two Weyl spinors gives rise to a Dirac spinor. Our analysis is applied also to the string geometry. The string constraints are represented by real spinors, which create a parametrization of the string worldsheet identical to the Enneper-Weierstass representation of minimal surfaces. Further, a spinorial study of the AdS3 spacetime reveals a Hopf fibration AdS3 \\rightarrow AdS2. The conformal symmetry inherent in AdS3 is pointed out. Our work indicates the hidden ties between logic-quantum mechanics-string theory-geometry and vindicates the Wheeler's proposal of pregeometry as a large network of logical propositions.
Hiroko Kato; Keng Tiong Tan
2005-01-01
2D barcodes were designed to carry significantly more data than its ID counterpart. These codes are often used in industrial information tagging applications where high data capacity, mobility, and data robustness are required. Mobile phones have evolved from just a mobile voice communication device to what is now a mobile multimedia computing platform. Recent integration of these two mobile technologies
2D gravity and random matrices
P. Di Francesco; P. Ginsparg; J. Zinn-Justin
1995-01-01
We review recent progress in 2D gravity coupled to d < 1 conformal matter, based on a representation of discrete gravity in terms of random matrices. We discuss the saddle point approximation for these models, including a class of related O(n) matrix models. For d < 1 matter, the matrix problem can be completely solved in many cases by the
Projective Geometry Introduction
Giger, Christine
Projective Geometry #12;Introduction · What is projective geometry? · an alternative algebraic is it good for? · projective geometry more convenient than Euclidean geometry to describe central projection progress #12;Introduction · Historical development · ca. 340: first mention of projective relations
ERIC Educational Resources Information Center
Scott, P. R.
1977-01-01
The good and bad points of Euclidean geometry and transformation geometry are briefly surveyed with emphasis on the teachability of Euclidean geometry and the mathematics of transformation geometry. (MN)
Animation : 2D versus 3D and their combined effect
Au, Kristin C
2014-01-01
This thesis studies the differences in the perception of space and character movement between 2D and 3D animation. 2D animation is defined by elements constructed in a 2D environment while 3D animation by elements constructed ...
Geometries for CAGD Helmut Pottmanna
Nawratil, Georg
modeling and addresses Euclidean, affine and projective geometry, as well as differential geometry widely known. These are projective differential geometric methods, sphere geometries, line geometry areas such as projective geometry, differential geometry and algebraic geometry. 1. Curves and Surfaces
ERIC Educational Resources Information Center
Scott, Paul
1988-01-01
Discusses the use of computer graphics in the teaching of geometry. Describes five types of geometry: Euclidean geometry, transformation geometry, coordinate geometry, three-dimensional geometry, and geometry of convex sets. (YP)
MIchael A. Pope
2010-02-01
Six early cores of the MASURCA R-Z program were modeled using ERANOS 2.1. These cores were designed such that their neutron spectra would be similar to that of an oxide-fueled sodium-cooled fast reactor, some containing enriched uranium and others containing depleted uranium and plutonium. Effects of modeling assumptions and solution methods both in ECCO lattice calculations and in BISTRO Sn flux solutions were evaluated using JEFF-3.1 cross-section libraries. Reactivity effects of differences between JEFF-3.1 and ENDF/B-VI.8 were also quantified using perturbation theory analysis. The most important nuclide with respect to reactivity differences between cross-section libraries was 23Na, primarily a result of differences in the angular dependence of elastic scattering which is more forward-peaked in ENDF/B-VI.8 than in JEFF-3.1. Differences in 23Na inelastic scattering cross-sections between libraries also generated significant differences in reactivity, more due to the differences in magnitude of the cross-sections than the angular dependence. The nuclide 238U was also found to be important with regard to reactivity differences between the two libraries mostly due to a large effect of inelastic scattering differences and two smaller effects of elastic scattering and fission cross-sections. In the cores which contained plutonium, 239Pu fission cross-section differences contributed significantly to the reactivity differences between libraries.
Bandgaps and directional propagation of elastic waves in 2D square zigzag lattice structures
NASA Astrophysics Data System (ADS)
Wang, Yan-Feng; Wang, Yue-Sheng; Zhang, Chuanzeng
2014-12-01
In this paper we propose various types of two-dimensional (2D) square zigzag lattice structures, and we study their bandgaps and directional propagation of elastic waves. The band structures and the transmission spectra of the systems are calculated by using the finite element method. The effects of the geometry parameters of the 2D-zigzag lattices on the bandgaps are investigated and discussed. The mechanism of the bandgap generation is analyzed by studying the vibration modes at the bandgap edges. Multiple wide complete bandgaps are found in a wide porosity range owing to the separation of the degeneracy by introducing bending arms. The bandgaps are sensitive to the geometry parameters of the systems. The deformed displacement fields of the transient response of finite structures subjected to time-harmonic loads are presented to show the directional wave propagation. The research in this paper is relevant to the practical design of cellular structures with enhanced vibro-acoustics performance.
Image 2D et Matrices Frank NIELSEN
Nielsen, Frank
.) Â· Compiler et tester le programme TestJama.java. Regarder rapidement la documentation des diffÂ´erentes dINF555 TD2 Image 2D et Matrices Frank NIELSEN nielsen@lix.polytechnique.fr 21 Septembre 2011 1 DÂ´etection temps Â´ecoulÂ´e depuis le 01/01/1970 (La diffÂ´erence entre deux appels mesure donc la dur
Compact 2-D graphical representation of DNA
NASA Astrophysics Data System (ADS)
Randi?, Milan; Vra?ko, Marjan; Zupan, Jure; Novi?, Marjana
2003-05-01
We present a novel 2-D graphical representation for DNA sequences which has an important advantage over the existing graphical representations of DNA in being very compact. It is based on: (1) use of binary labels for the four nucleic acid bases, and (2) use of the 'worm' curve as template on which binary codes are placed. The approach is illustrated on DNA sequences of the first exon of human ?-globin and gorilla ?-globin.
2-D color code quantum computation
Austin G. Fowler
2011-01-10
We describe in detail how to perform universal fault-tolerant quantum computation on a 2-D color code, making use of only nearest neighbor interactions. Three defects (holes) in the code are used to represent logical qubits. Triple defect logical qubits are deformed into isolated triangular sections of color code to enable transversal implementation of all single logical qubit Clifford group gates. CNOT is implemented between pairs of triple defect logical qubits via braiding.
2D array based on fermat spiral
NASA Astrophysics Data System (ADS)
Martínez, O.; Martín, C. J.; Godoy, G.; Ullate, L. G.
2010-01-01
The main challenge faced by 3D ultrasonic imaging with 2D array transducer is the large number of elements required to achieve an acceptable level of quality in the images. Therefore, the optimization of the array layout to reduce the number of active elements in the aperture has been a research topic in the last years. Nowadays, CMUT array technology has made viable the production of 2D arrays with larger flexibility on elements size, shape and position. This is opening new options in 2D array design, allowing to revise as viable alternatives others layouts that had been studied in the past, like circular and Archimedes spiral layout. In this work the problem of designing an imaging system array with a diameter of 60 ? and a limited number of elements using the Fermat spiral layout has been studied. This study has been done for two different numbers of electronic channels (N = 128 and N = 256). As summary, a general discussion of the results and the most interesting cases are presented.
MAGNUM-2D computer code: user's guide
England, R.L.; Kline, N.W.; Ekblad, K.J.; Baca, R.G.
1985-01-01
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.
3D reconstruction of a carotid bifurcation from 2D transversal ultrasound images.
Yeom, Eunseop; Nam, Kweon-Ho; Jin, Changzhu; Paeng, Dong-Guk; Lee, Sang-Joon
2014-12-01
Visualizing and analyzing the morphological structure of carotid bifurcations are important for understanding the etiology of carotid atherosclerosis, which is a major cause of stroke and transient ischemic attack. For delineation of vasculatures in the carotid artery, ultrasound examinations have been widely employed because of a noninvasive procedure without ionizing radiation. However, conventional 2D ultrasound imaging has technical limitations in observing the complicated 3D shapes and asymmetric vasodilation of bifurcations. This study aims to propose image-processing techniques for better 3D reconstruction of a carotid bifurcation in a rat by using 2D cross-sectional ultrasound images. A high-resolution ultrasound imaging system with a probe centered at 40MHz was employed to obtain 2D transversal images. The lumen boundaries in each transverse ultrasound image were detected by using three different techniques; an ellipse-fitting, a correlation mapping to visualize the decorrelation of blood flow, and the ellipse-fitting on the correlation map. When the results are compared, the third technique provides relatively good boundary extraction. The incomplete boundaries of arterial lumen caused by acoustic artifacts are somewhat resolved by adopting the correlation mapping and the distortion in the boundary detection near the bifurcation apex was largely reduced by using the ellipse-fitting technique. The 3D lumen geometry of a carotid artery was obtained by volumetric rendering of several 2D slices. For the 3D vasodilatation of the carotid bifurcation, lumen geometries at the contraction and expansion states were simultaneously depicted at various view angles. The present 3D reconstruction methods would be useful for efficient extraction and construction of the 3D lumen geometries of carotid bifurcations from 2D ultrasound images. PMID:24965564
Toward an Efficient Icing CFD Process Using an Interactive Software Toolkit--SmaggIce 2D
Mary B. Vickerman; Yung K. Choo; Herbert W. Schilling; Marivell Baez; Donald C. Braun; Barbara J. Cotton
2002-01-01
Two-dimensional CFD analysis for iced airfoils can be a labor-intensive task. The software toolkit SmaggIce 2D is being developed to help streamline the CFD process and provide the unique features needed for icing. When complete, it will include a combination of partially automated and fully interactive tools for all aspects of the tasks leading up to the flow analysis: geometry
Interrogating Fiber Formation Kinetics with Automated 2D-IR Spectroscopy
NASA Astrophysics Data System (ADS)
Strasfeld, David B.; Ling, Yun L.; Shim, Sang-Hee; Zanni, Martin T.
A new method for collecting 2D-IR spectra that utilizes both a pump-probe beam geometry and a mid-IR pulse shaper is used to gain a fuller understanding of fiber formation in the human islet amyloid polypeptide (hIAPP). We extract structural kinetics in order to better understand aggregation in hIAPP, the protein component of the amyloid fibers found to inhibit insulin production in type II diabetes patients.
Yasuhiro Yamada; Ken McClay
2003-01-01
Fault geometry is a primary control on hanging wall deformation. In order to examine their geometrical relationships, a positive inversion analogue experiment was conducted using a rigid fault surface of listric geometry. The hanging wall deformation observed on a representative vertical section was examined with conventional 2D geometric models, and was restored to its pre-inversion phase with two techniques. These
Gideon, Rudy A.
Projective Geometry and Pappus' Theorem Kelly McKinnie History Pappus' Theorem Geometries Picturing the projective plane Lines in projective geometry Back to Pappus' Theorem Proof of Pappus' Theorem Projective Geometry and Pappus' Theorem Kelly McKinnie March 23, 2010 #12;Projective Geometry and Pappus' Theorem
CSY3019 -Graphics Programming Assignment 1: Development of 2D/3D graphics software: Java 2D (50%)
Hill, Gary
CSY3019 - Graphics Programming Assignment 1: Development of 2D/3D graphics software: Java 2D (50 Office). Brief: Produce a technical report and accompanying application using Java 2D. The Java Swing application is to include a Java 2D graphical representation of the instrument panel from a car. An image
CSY3019 -Graphics Programming Assignment 1: Development of 2D/3D graphics software: Java 2D (50%)
Hill, Gary
CSY3019 - Graphics Programming Assignment 1: Development of 2D/3D graphics software: Java 2D (50 Office). Brief: Produce a technical report and accompanying application using Java 2D. The Java Swing application is to include a Java 2D graphical representation of a disc rotor. A partial image of the disc
CSY3019 -Graphics Programming Assignment 1: Development of 2D/3D graphics software: Java 2D (50%)
Hill, Gary
CSY3019 - Graphics Programming Assignment 1: Development of 2D/3D graphics software: Java 2D (50 Office). Brief: Produce a technical report and accompanying application using Java 2D. The Java Swing application is to include a Java 2D graphical representation of a dartboard and a snooker table. Partial
WFR-2D: an analytical model for PWAS-generated 2D ultrasonic guided wave propagation
NASA Astrophysics Data System (ADS)
Shen, Yanfeng; Giurgiutiu, Victor
2014-03-01
This paper presents WaveFormRevealer 2-D (WFR-2D), an analytical predictive tool for the simulation of 2-D ultrasonic guided wave propagation and interaction with damage. The design of structural health monitoring (SHM) systems and self-aware smart structures requires the exploration of a wide range of parameters to achieve best detection and quantification of certain types of damage. Such need for parameter exploration on sensor dimension, location, guided wave characteristics (mode type, frequency, wavelength, etc.) can be best satisfied with analytical models which are fast and efficient. The analytical model was constructed based on the exact 2-D Lamb wave solution using Bessel and Hankel functions. Damage effects were inserted in the model by considering the damage as a secondary wave source with complex-valued directivity scattering coefficients containing both amplitude and phase information from wave-damage interaction. The analytical procedure was coded with MATLAB, and a predictive simulation tool called WaveFormRevealer 2-D was developed. The wave-damage interaction coefficients (WDICs) were extracted from harmonic analysis of local finite element model (FEM) with artificial non-reflective boundaries (NRB). The WFR-2D analytical simulation results were compared and verified with full scale multiphysics finite element models and experiments with scanning laser vibrometer. First, Lamb wave propagation in a pristine aluminum plate was simulated with WFR-2D, compared with finite element results, and verified by experiments. Then, an inhomogeneity was machined into the plate to represent damage. Analytical modeling was carried out, and verified by finite element simulation and experiments. This paper finishes with conclusions and suggestions for future work.
ENERGY LANDSCAPE OF 2D FLUID FORMS
Y. JIANG; ET AL
2000-04-01
The equilibrium states of 2D non-coarsening fluid foams, which consist of bubbles with fixed areas, correspond to local minima of the total perimeter. (1) The authors find an approximate value of the global minimum, and determine directly from an image how far a foam is from its ground state. (2) For (small) area disorder, small bubbles tend to sort inwards and large bubbles outwards. (3) Topological charges of the same sign repel while charges of opposite sign attract. (4) They discuss boundary conditions and the uniqueness of the pattern for fixed topology.
Algebraic geometry versus Kahler geometry Claire Voisin
Voisin, Claire
Algebraic geometry versus KÂ¨ahler geometry Claire Voisin CNRS, Institut de mathÂ´ematiques de THEORY AND GEOMETRY" organized by the Riemann International School of Mathematics in Verbania. The first, but topologi- cally non KÂ¨ahler. More precisely, the projective manifolds will have a Hodge structure
2-D or not 2-D, that is the question: A Northern California test
Mayeda, K; Malagnini, L; Phillips, W S; Walter, W R; Dreger, D
2005-06-06
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.
ERIC Educational Resources Information Center
Burn, Bob
1990-01-01
Compared is the use of Euclidean and synthetic geometry in American and European schools. Included is the history of the major developments in the teaching of geometry. Discussed is the demise of formal geometry since World War II. (KR)
A Computational Study of Metal-Contacts to Beyond-Graphene 2D Semiconductor Materials Jiahao Kang+
A Computational Study of Metal-Contacts to Beyond-Graphene 2D Semiconductor Materials Jiahao Kang. For applicability of these novel materials as transistors, a comprehensive understanding of metal contacts to them-TMD contacts with different geometries (end-contacts and side-contacts) by ab-initio density functional theory
Intermittency in 2D soap film turbulence
NASA Astrophysics Data System (ADS)
Cerbus, R. T.; Goldburg, W. I.
2013-10-01
The Reynolds number dependency of intermittency for 2D turbulence is studied in a flowing soap film. The Reynolds number used here is the Taylor microscale Reynolds number R?, which ranges from 20 to 800. Strong intermittency is found for both the inverse energy and direct enstrophy cascades as measured by (a) the pdf of velocity differences P(?u(r)) at inertial scales r, (b) the kurtosis of P(?xu), and (c) the scaling of the so-called intermittency exponent ?, which is zero if intermittency is absent. Measures (b) and (c) are quantitative, while (a) is qualitative. These measurements are in disagreement with some previous results but not all. The velocity derivatives are nongaussian at all R? but show signs of becoming gaussian as R? increases beyond the largest values that could be reached. The kurtosis of P(?u(r)) at various r indicates that the intermittency is scale dependent. The structure function scaling exponents also deviate strongly from the Kraichnan prediction. For the enstrophy cascade, the intermittency decreases as a power law in R?. This study suggests the need for a new look at the statistics of 2D turbulence.
A 2D driven 3D vessel segmentation algorithm for 3D digital subtraction angiography data
NASA Astrophysics Data System (ADS)
Spiegel, M.; Redel, T.; Struffert, T.; Hornegger, J.; Doerfler, A.
2011-10-01
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.
Christian Bar Differential Geometry
Baer, Christian
.5 Trigonometry in spaces of constant curvature . . . . . . . . . . . . . . . . 133 5 Riemannian Geometry 143 5 apply differential geometry to derive the laws of trigonometry on spaces of constant curvature. One
Novel Fermi Liquid of 2D Polar Molecules
Zhen-Kai Lu; G. V. Shlyapnikov
2011-11-30
We study Fermi liquid properties of a weakly interacting 2D gas of single-component fermionic polar molecules with dipole moments $d$ oriented perpendicularly to the plane of their translational motion. This geometry allows the minimization of inelastic losses due to chemical reactions for reactive molecules and, at the same time, provides a possibility of a clear description of many-body (beyond mean field) effects. The long-range character of the dipole-dipole repulsive interaction between the molecules, which scales as $1/r^3$ at large distances $r$, makes the problem drastically different from the well-known problem of the two-species Fermi gas with repulsive contact interspecies interaction. We solve the low-energy scattering problem and develop a many-body perturbation theory beyond the mean field. The theory relies on the presence of a small parameter $k_Fr_*$, where $k_F$ is the Fermi momentum, and $r_*=md^2/\\hbar^2$ is the dipole-dipole length, with $m$ being the molecule mass. We obtain thermodynamic quantities as a series of expansion up to the second order in $k_Fr_*$ and argue that many-body corrections to the ground-state energy can be identified in experiments with ultracold molecules, like it has been recently done for ultracold fermionic atoms. Moreover, we show that only many-body effects provide the existence of zero sound and calculate the sound velocity.
Defect formation and coarsening in hexagonal 2D curved crystals.
García, Nicolás A; Pezzutti, Aldo D; Register, Richard A; Vega, Daniel A; Gómez, Leopoldo R
2015-02-01
In this work we study the processes of defect formation and coarsening of two-dimensional (2D) curved crystal structures. These processes are found to strongly deviate from their counterparts in flat systems. In curved backgrounds the process of defect formation is deeply affected by the curvature, and at the onset of a phase transition the early density of defects becomes highly inhomogeneous. We observe that even a single growing crystal can produce varying densities of defects depending on its initial position and local orientation with regard to the substrate. This process is completely different from flat space, where grain boundaries are formed due to the impingement of different propagating crystals. Quenching the liquid into the crystal phase leads to the formation of a curved polycrystalline structure, characterized by complex arrays of defects. During annealing, mechanisms of geodesic curvature-driven grain boundary motion and defect annihilation lead to increasing crystalline order. Linear arrays of defects diffuse to regions of high curvature, where they are absorbed by disclinations. At the early stage of coarsening the density of dislocations is insensitive to the geometry while the population of isolated disclinations is deeply affected by curvature. The regions with high curvature act as traps for the diffusion of different structures of defects, including disclinations and domain walls. PMID:25491780
2D Fluidization of Nanomaterials by Biomimetic Membranes
NASA Astrophysics Data System (ADS)
Kelly, Kathleen; Forstner, Martin
2013-03-01
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.
2D Fluidization of Nanomaterials by Biomimetic Membranes
NASA Astrophysics Data System (ADS)
Kelly, Kathleen; Forstner, Martin
2012-02-01
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.
2D axisymmetric analysis of SRM ignition transient
NASA Astrophysics Data System (ADS)
Bai, S. D.; Han, Samuel S.; Pardue, B. A.
1993-06-01
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.
2D-fractal based algorithms for nanoparticles characterization
NASA Astrophysics Data System (ADS)
Bonifazi, Giuseppe; Serranti, Silvia
2014-02-01
Fractal geometry concerns the study of non-Euclidean geometrical figures generated by a recursive sequence of mathematical operations. The proposed 2D-fractal approach was applied to characterise the image structure and texture generated by fine and ultra-fine particles when impacting on a flat surface. The work was developed with reference to particles usually produced by ultra-fine milling addressed to generate nano-particles population. In order to generate different particle populations to utilize in the study, specific milling actions have been thus performed adopting different milling actions and utilising different materials, both in terms of original size class distribution and chemical-physical attributes. The aim of the work was to develop a simple, reliable and low cost analytical set of procedures with the ability to establish correlations between particles detected by fractal characteristics and their milled-induced-properties (i.e. size class distribution, shape, surface properties, etc.). Such logic should constitute the core of a control engine addressed to realize a full monitoring of the milling process as well as to establish correlation between operative parameters, fed and resulting products characteristics.
Comparative metabolic capabilities and inhibitory profiles of CYP2D6.1, CYP2D6.10, and CYP2D6.17.
Shen, Hongwu; He, Minxia M; Liu, Houfu; Wrighton, Steven A; Wang, Li; Guo, Bin; Li, Chuan
2007-08-01
Polymorphisms in the cytochrome P450 2D6 (CYP2D6) gene are a major cause of pharmacokinetic variability in human. Although the poor metabolizer phenotype is known to be caused by two null alleles leading to absence of functional CYP2D6 protein, the large variability among individuals with functional alleles remains mostly unexplained. Thus, the goal of this study was to examine the intrinsic enzymatic differences that exist among the several active CYP2D6 allelic variants. The relative catalytic activities (enzyme kinetics) of three functionally active human CYP2D6 allelic variants, CYP2D6.1, CYP2D6.10, and CYP2D6.17, were systematically investigated for their ability to metabolize a structurally diverse set of clinically important CYP2D6-metabolized drugs [atomoxetine, bufuralol, codeine, debrisoquine, dextromethorphan, (S)-fluoxetine, nortriptyline, and tramadol] and the effects of various CYP2D6-inhibitors [cocaine, (S)-fluoxetine, (S)-norfluoxetine, imipramine, quinidine, and thioridazine] on these three variants. The most significant difference observed was a consistent but substrate-dependent decease in the catalytic efficiencies of cDNA-expressed CYP2D6.10 and CYP2D6.17 compared with CYP2D6.1, yielding 1.32 to 27.9 and 7.33 to 80.4% of the efficiency of CYP2D6.1, respectively. The most important finding from this study is that there are mixed effects on the functionally reduced allelic variants in enzyme-substrate affinity or enzyme-inhibitor affinity, which is lower, higher, or comparable to that for CYP2D6.1. Considering the rather high frequencies of CYP2D6*10 and CYP2D6*17 alleles for Asians and African Americans, respectively, these data provide further insight into ethnic differences in CYP2D6-mediated drug metabolism. However, as with all in vitro to in vivo extrapolations, caution should be applied to the clinical consequences. PMID:17470523
Linear line spectropolarimetry as a new window to measure 2D and 3D wind geometries
NASA Astrophysics Data System (ADS)
Vink, Jorick S.
2015-01-01
Various theories have been proposed to predict how mass loss depends on the stellar rotation rate, both in terms of its strength, as well as its latitudinal dependence, crucial for our understanding of angular momentum evolution. Here we discuss the tool of linear spectropolarimetry that can probe the difference between mass loss from the pole versus the equator. Our results involve several groups of O stars and Wolf-Rayet stars, involving Oe stars, Of?p stars, Onfp stars, as well as the best candidate gamma-ray burst progenitors identified to date.
Pauli matrices and 2D electron gas
J. F. Geurdes
2013-02-07
In the present paper it will be argued that transport in a 2D electron gas can be implemented as 'local hidden instrument based' variables. With this concept of instrumentalism it is possible to explain the quantum correlation, the particle-wave duality and Wheeler's 'backward causation of a particle'. In the case of quantum correlation the spin measuring variant of the Einstein Podolsky and Rosen paradox is studied. In the case of particle-wave duality the system studied is single photon Mach-Zehnder (MZ) interferometry with a phase shift size $\\delta$. The idea that the instruments more or less neutrally may show us the way to the particle will be replaced by the concept of laboratory equipment contributing in an unexpected way to the measurement.
2-D gel electrophoresis: constructing 2D-gel proteome reference maps.
Simula, Maria Paola; Notarpietro, Agata; Toffoli, Giuseppe; De Re, Valli
2012-01-01
Two-dimensional gel electrophoresis (2-DE) is the most popular and versatile method of protein separation among a rapidly growing array of proteomic technologies. Based on two independent biochemical characteristics of proteins, it combines isoelectric focusing, which separates proteins according to their isoelectric point (pI), and SDS-PAGE, which separates them further according to their molecular mass. An evolution of conventional 2-DE is represented by the 2D-Difference in Gel Electrophoresis (2D-DIGE) that allows sample multiplexing and achieving more accurate and sensitive quantitative proteomic determinations. The 2-DE separation permits the generation of protein maps of different cells or tissues and the study, by differential proteomics, of protein expression changes associated to the different states of a biological system. In order to identify the molecular bases of pathological processes, it is also useful to characterize the physiological protein homeostasis in healthy cells or tissues. On these grounds, the availability of detailed 2D reference maps could be very useful for proteomic studies. The protocol described in this chapter is based on the 2D-DIGE technology and has been applied to obtain the first 2-DE reference map of the human small intestine. PMID:22130991
2D discrete Fourier transform on sliding windows.
Park, Chun-Su
2015-03-01
Discrete Fourier transform (DFT) is the most widely used method for determining the frequency spectra of digital signals. In this paper, a 2D sliding DFT (2D SDFT) algorithm is proposed for fast implementation of the DFT on 2D sliding windows. The proposed 2D SDFT algorithm directly computes the DFT bins of the current window using the precalculated bins of the previous window. Since the proposed algorithm is designed to accelerate the sliding transform process of a 2D input signal, it can be directly applied to computer vision and image processing applications. The theoretical analysis shows that the computational requirement of the proposed 2D SDFT algorithm is the lowest among existing 2D DFT algorithms. Moreover, the output of the 2D SDFT is mathematically equivalent to that of the traditional DFT at all pixel positions. PMID:25585421
PROJECTIVE GEOMETRY KRISTIN DEAN
May, J. Peter
PROJECTIVE GEOMETRY KRISTIN DEAN Abstract. This paper investigates the nature of finite geometries. It will focus on the finite geometries known as projective planes and conclude with the example of the Fano plane. Contents 1. Basic Definitions 1 2. Axioms of Projective Geometry 2 3. Linear Algebra
Baldwin, John T.
Analytic Structures Geometry and Categoricity John T. Baldwin January 8, 2012 #12;Geometry and Categoricity Homogeneity Zariski Structures Analytic Structures Whig History #12;Geometry and Categoricity John T. Baldwin in (C, +, Â·) by `analytically' definable. Response #12;Geometry and Categoricity John T. Baldwin
ERIC Educational Resources Information Center
Cukier, Mimi; Asdourian, Tony; Thakker, Anand
2012-01-01
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…
On 2D graphical representation of DNA sequence of nondegeneracy
NASA Astrophysics Data System (ADS)
Zhang, Yusen; Liao, Bo; Ding, Kequan
2005-08-01
Some two-dimensional (2D) graphical representations of DNA sequences have been given by Gates, Nandy, Leong and Mogenthaler, Randi?, and Liao et al., which give visual characterizations of DNA sequences. In this Letter, we introduce a nondegeneracy 2D graphical representation of DNA sequence, which is different from Randi?'s novel 2D representation and Liao's 2D representation. We also present the nondegeneracy forms corresponding to the representations of Gates, Nandy, Leong and Mogenthaler.
Monistic conception of geometry
Yuri A. Rylov
2010-09-15
One considers the monistic conception of a geometry, where there is only one fundamental quantity (world function). All other geometrical quantities a derivative quantities (functions of the world function). The monisitc conception of a geometry is compared with pluralistic conceptions of a geometry, where there are several independent fundamental geometrical quantities. A generalization of a pluralistic conception of the proper Euclidean geometry appears to be inconsistent, if the generalized geometry is inhomogeneous. In particular, the Riemannian geometry appears to be inconsistent, in general, if it is obtained as a generalization of the pluralistic conception of the Euclidean geometry.
Simplified 2D Bidomain Model of Whole Heart Electrical Activity and ECG Generation
NASA Astrophysics Data System (ADS)
Sovilj, Siniša; Magjarevi?, Ratko; Abed, Amr Al; Lovell, Nigel H.; Dokos, Socrates
2014-06-01
The aim of this study was the development of a geometrically simple and highly computationally-efficient two dimensional (2D) biophysical model of whole heart electrical activity, incorporating spontaneous activation of the sinoatrial node (SAN), the specialized conduction system, and realistic surface ECG morphology computed on the torso. The FitzHugh-Nagumo (FHN) equations were incorporated into a bidomain finite element model of cardiac electrical activity, which was comprised of a simplified geometry of the whole heart with the blood cavities, the lungs and the torso as an extracellular volume conductor. To model the ECG, we placed four electrodes on the surface of the torso to simulate three Einthoven leads VI, VII and VIII from the standard 12-lead system. The 2D model was able to reconstruct ECG morphology on the torso from action potentials generated at various regions of the heart, including the sinoatrial node, atria, atrioventricular node, His bundle, bundle branches, Purkinje fibers, and ventricles. Our 2D cardiac model offers a good compromise between computational load and model complexity, and can be used as a first step towards three dimensional (3D) ECG models with more complex, precise and accurate geometry of anatomical structures, to investigate the effect of various cardiac electrophysiological parameters on ECG morphology.
Computational Information Geometry From Euclidean to flat Pythagorean geometries
Nielsen, Frank
geometry: Customize geometries to datasets, generic non-Euclidean algorithmic toolboxes. George E. P. BoxComputational Information Geometry From Euclidean to flat Pythagorean geometries Frank Nielsen persistence), Recover intrinsic geometry (eg., distance learning, invariants) Computational information
NSDL National Science Digital Library
Mrs Burch
2006-12-08
Geometrical shapes can be the beginning of a strong geometrical foundation Geometry can be great fun. Check out these websites and start having some fun with shapes. Spend 10 minutes with this siteGeometry- Making Our Own Shapes. After you have made some shapes, check out this site Geometry is Great! to see that Geometry is Great. You can spend time on this site Groovy Geometry if you ...
Lott, Geoffrey A.; Perdomo-Ortiz, Alejandro; Utterback, James K.; Widom, Julia R.; Aspuru-Guzik, Alán; Marcus, Andrew H.
2011-01-01
By applying a phase-modulation fluorescence approach to 2D electronic spectroscopy, we studied the conformation-dependent exciton coupling of a porphyrin dimer embedded in a phospholipid bilayer membrane. Our measurements specify the relative angle and separation between interacting electronic transition dipole moments and thus provide a detailed characterization of dimer conformation. Phase-modulation 2D fluorescence spectroscopy (PM-2D FS) produces 2D spectra with distinct optical features, similar to those obtained using 2D photon-echo spectroscopy. Specifically, we studied magnesium meso tetraphenylporphyrin dimers, which form in the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine liposomes. Comparison between experimental and simulated spectra show that although a wide range of dimer conformations can be inferred by either the linear absorption spectrum or the 2D spectrum alone, consideration of both types of spectra constrain the possible structures to a “T-shaped” geometry. These experiments establish the PM-2D FS method as an effective approach to elucidate chromophore dimer conformation. PMID:21940499
2D/3D Visual Tracker for Rover Mast
NASA Technical Reports Server (NTRS)
Bajracharya, Max; Madison, Richard W.; Nesnas, Issa A.; Bandari, Esfandiar; Kunz, Clayton; Deans, Matt; Bualat, Maria
2006-01-01
A visual-tracker computer program controls an articulated mast on a Mars rover to keep a designated feature (a target) in view while the rover drives toward the target, avoiding obstacles. Several prior visual-tracker programs have been tested on rover platforms; most require very small and well-estimated motion between consecutive image frames a requirement that is not realistic for a rover on rough terrain. The present visual-tracker program is designed to handle large image motions that lead to significant changes in feature geometry and photometry between frames. When a point is selected in one of the images acquired from stereoscopic cameras on the mast, a stereo triangulation algorithm computes a three-dimensional (3D) location for the target. As the rover moves, its body-mounted cameras feed images to a visual-odometry algorithm, which tracks two-dimensional (2D) corner features and computes their old and new 3D locations. The algorithm rejects points, the 3D motions of which are inconsistent with a rigid-world constraint, and then computes the apparent change in the rover pose (i.e., translation and rotation). The mast pan and tilt angles needed to keep the target centered in the field-of-view of the cameras (thereby minimizing the area over which the 2D-tracking algorithm must operate) are computed from the estimated change in the rover pose, the 3D position of the target feature, and a model of kinematics of the mast. If the motion between the consecutive frames is still large (i.e., 3D tracking was unsuccessful), an adaptive view-based matching technique is applied to the new image. This technique uses correlation-based template matching, in which a feature template is scaled by the ratio between the depth in the original template and the depth of pixels in the new image. This is repeated over the entire search window and the best correlation results indicate the appropriate match. The program could be a core for building application programs for systems that require coordination of vision and robotic motion.
Black Hole Geometries in Noncommutative String Theory
Supriya Kar; Sumit Majumdar
2005-10-05
We obtain a generalized Schwarzschild (GS-) and a generalized Reissner-Nordstrom (GRN-) black hole geometries in (3+1)-dimensions, in a noncommutative string theory. In particular, we consider an effective theory of gravity on a curved $D_3$-brane in presence of an electromagnetic (EM-) field. Two different length scales, inherent in its noncommutative counter-part, are exploited to obtain a theory of effective gravity coupled to an U(1) noncommutative gauge theory to all orders in $\\Theta$. It is shown that the GRN-black hole geometry, in the Planckian regime, reduces to the GS-black hole. However in the classical regime it may be seen to govern both Reissner-Nordstrom and Schwarzschild geometries independently. The emerging notion of 2D black holes evident in the frame-work are analyzed. It is argued that the $D$-string in the theory may be described by the near horizon 2D black hole geometry, in the gravity decoupling limit. Finally, our analysis explains the nature of the effective force derived from the nonlinear EM-field and accounts for the Hawking radiation phenomenon in the formalism.
Intermittency in 2D soap film turbulence
Cerbus, R T
2013-01-01
The Reynolds number dependency of intermittency for 2D turbulence is studied in a flowing soap film. The Reynolds number used here is the Taylor microscale Reynolds number R_{\\lambda}, which ranges from 20 to 800. Strong intermittency is found for both the inverse energy and direct enstrophy cascades as measured by (a) the pdf of velocity differences P(\\delta u(r)) at inertial scales r, (b) the kurtosis of P(\\partial_x u), and (c) the scaling of the so-called intermittency exponent \\mu, which is zero if intermittency is absent. Measures (b) and (c) are quantitative, while (a) is qualitative. These measurements are in disagreement with some previous results but not all. The velocity derivatives are nongaussian at all R_{\\lambda} but show signs of becoming gaussian as R_{\\lambda} increases beyond the largest values that could be reached. The kurtosis of P(\\delta u(r)) at various r indicates that the intermittency is scale dependent. The structure function scaling exponents also deviate strongly from the Kraichn...
2D Radiative Processes Near Cloud Edges
NASA Technical Reports Server (NTRS)
Varnai, T.
2012-01-01
Because of the importance and complexity of dynamical, microphysical, and radiative processes taking place near cloud edges, the transition zone between clouds and cloud free air has been the subject of intense research both in the ASR program and in the wider community. One challenge in this research is that the one-dimensional (1D) radiative models widely used in both remote sensing and dynamical simulations become less accurate near cloud edges: The large horizontal gradients in particle concentrations imply that accurate radiative calculations need to consider multi-dimensional radiative interactions among areas that have widely different optical properties. This study examines the way the importance of multidimensional shortwave radiative interactions changes as we approach cloud edges. For this, the study relies on radiative simulations performed for a multiyear dataset of clouds observed over the NSA, SGP, and TWP sites. This dataset is based on Microbase cloud profiles as well as wind measurements and ARM cloud classification products. The study analyzes the way the difference between 1D and 2D simulation results increases near cloud edges. It considers both monochromatic radiances and broadband radiative heating, and it also examines the influence of factors such as cloud type and height, and solar elevation. The results provide insights into the workings of radiative processes and may help better interpret radiance measurements and better estimate the radiative impacts of this critical region.
AN INTRODUCTION TO SYMPLECTIC GEOMETRY,
Schürmann, Michael
AN INTRODUCTION TO SYMPLECTIC GEOMETRY, HAMILTON SYSTEMS, AND COMPLEX GEOMETRY Rainer Schimming Szczecin 2002 #12; AN INTRODUCTION TO SYMPLECTIC GEOMETRY, HAMILTON SYSTEMS, AND COMPLEX GEOMETRY Rainer Poisson and symplectic geometries 8 2.1 Poisson manifolds
Thermodynamic geometry and extremal black holes in string theory
Tapobrata Sarkar; Gautam Sengupta; Bhupendra Nath Tiwari
2008-01-01
We study a generalisation of thermodynamic geometry to degenerate quantum ground states at zero temperatures exemplified by charged extremal black holes in type II string theories. Several examples of extremal charged black holes with non degenerate thermodynamic geometries and regular but vanishingly small state space scalar curvatures are established. These include black holes described by D1-D5-P and D2-D6-NS5-P brane systems
Transmutation of Pure 2-D Supergravity Into Topological 2-D Gravity and Other Conformal Theories
Laurent Baulieu
1992-06-04
We consider the BRST and superconformal properties of the ghost action of 2-D supergravity. Using the background spin structure on the worldsheet, we show that this action can be transformed by canonical field transformations to reach other conformal models such as the 2-D topological gravity or the chiral models for which the gauge variation of the action reproduces the left or right conformal anomaly. Our method consists in using the gravitino and its ghost as fundamental blocks to build fields with different conformal weights and statistics. This indicates in particular that the twisting of a conformal model into another one can be classically interpreted as a change of "field representation" of the superconformal symmetry.
Position control using 2D-to-2D feature correspondences in vision guided cell micromanipulation.
Zhang, Yanliang; Han, Mingli; Shee, Cheng Yap; Ang, Wei Tech
2007-01-01
Conventional camera calibration that utilizes the extrinsic and intrinsic parameters of the camera and the objects has certain limitations for micro-level cell operations due to the presence of hardware deviations and external disturbances during the experimental process, thereby invalidating the extrinsic parameters. This invalidation is often neglected in macro-world visual servoing and affects the visual image processing quality, causing deviation from the desired position in micro-level cell operations. To increase the success rate of vision guided biological micromanipulations, a novel algorithm monitoring the changing image pattern of the manipulators including the injection micropipette and cell holder is designed and implemented based on 2 dimensional (2D)-to 2D feature correspondences and can adjust the manipulator and perform position control simultaneously. When any deviation is found, the manipulator is retracted to the initial focusing plane before continuing the operation. PMID:18002239
NKG2D CARs as Cell Therapy for Cancer
Sentman, Charles L.; Meehan, Kenneth R.
2014-01-01
The NKG2D cell receptor and its ligands have attracted considerable interest as a potential strategy to attack tumor cells. NKG2D ligands are expressed on most types of tumors, and they demonstrate relative selectivity of ligand expression on tumor cells compared with healthy cells. Several different variants of NKG2D-based chimeric antigen receptors (CAR) have been developed and extensive in vivo mechanistic studies performed demonstrating that cytotoxicity and cytokines are important for the efficacy NKG2D CAR adoptive T cell therapy. NKG2D CARs target tumor cells and they also target immunosuppressive cells within the tumor microenvironment. Under certain conditions, NKG2D ligand expression can be found on non-tumor tissue, so potential off-tumor toxicity remain. In this article, we review the use of NKG2D as a basis for CAR targeting of tumors. PMID:24667963
Amoeboid motion in confined geometry
Wu, Hao; Hu, Wei-Fan; Farutin, Alexander; Rafaï, Salima; Lai, Ming-Chih; Peyla, Philippe; Misbah, Chaouqi
2015-01-01
Cells of the immune system, as well as cancer cells, migrating in confined environment of tissues undergo frequent shape changes (described as amoeboid motion) that enable them to move forward through these porous media without the assistance of adhesion sites. In other words, they perform amoeboid swimming (AS) while using extracellular matrices and cells of tissues as support. We introduce a simple model of AS in a confined geometry solved by means of 2D numerical simulations. We find that confinement promotes AS, unless being so strong that it restricts shape change amplitude. A straight AS trajectory in the channel is found to be unstable, and ample lateral excursions of the swimmer prevail. For weak confinement, these excursions are symmetric, while they become asymmetric at stronger confinement, whereby the swimmer is located closer to one of the two walls. This is a spontaneous symmetry-breaking bifurcation. We find that there exists an optimal confinement for migration. We provide numerical results as...
Exploring Geometry Using Cabri Jr. Geometry App
Leah A. Nillas
2010-01-01
This is a Hands-on session and an introduction to the Cabri Jr. Geometry App. Participants will learn basic commands in using the Cabri Jr. Geometry App as well as explore geometric constructions and relationships. Activities in this session are designed to engage students in discovering geometric relationships and making mathematical connections. Topics that will be covered include lines, angles, triangles,
Learning Geometry through Dynamic Geometry Software
ERIC Educational Resources Information Center
Forsythe, Sue
2007-01-01
In this article, the author investigates effective teaching and learning of geometrical concepts using dynamic geometry software (DGS). Based from her students' reactions to her project, the author found that her students' understanding of the concepts was better than if they had learned geometry through paper-based tasks. However, mixing computer…
A Polyhedral Object's CSG-Rep Reconstruction From a Single 2D Line Drawing
NASA Astrophysics Data System (ADS)
Wang, Weidong; Grinstein, Georges G.
1990-03-01
The interpretation of a 2D line drawing as a 3D scene is an important area of study within the fields of artificial intelligence and machine vision. In the area of CAD/CAM, research has focused on the reconstruction of a 3D solid from its engineering drawings, either with two views or three views, or from its wireframe representation. We have been working on the problem of automatically reconstructing a 3D solid object's Constructive Solid Geometry (CSG) representation from a single 2D line drawing of the object. This paper describes our approach as well as some preliminary results. We validate our approach on a restricted set of objects consisting of simple rectilinear polyhedra. Using the Huffman-Clowes labeling scheme we are able to successfully identify the primitive blocks necessary for the CSG tree generation, as well as the set operations that must be applied to them. Extension to general polyhedra is also discussed.
Numerical investigation of convection-induced MHD waves interacting with a null point in 2D
NASA Astrophysics Data System (ADS)
Tarr, Lucas A.; Linton, Mark G.; Leake, James
2015-04-01
We use the LaRe2D MHD code to investigate the propagation of waves in a 2D geometry that includes a quadrupolar magnetic field with a single nullpoint. The simulation box spans the upper convection zone to the corona (y=[-3Mm,35.4Mm] ) and includes a stratified atmosphere. We model the upper convection zone by introducing an energy flux at the lower boundary, an ad-hoc Newton-cooling term to simulate the effect of radiation at the photosphere (y=0), and an initial condition that includes density and internal energy perturbations throughout the convection zone. This sets up the superadiabatic temperature gradient necessary to sustain convection and generate waves. We discuss the dynamic properties of these waves as they propagate through the atmosphere and interact at topologically important features of the magnetic field. This work is funded by the Chief of Naval Research.
Pythagoras' Theorem on a 2D-Lattice from a "Natural" Dirac Operator and Connes' Distance Formula
Jian Dai; Xing-Chang Song
2001-01-15
One of the key ingredients of A. Connes' noncommutative geometry is a generalized Dirac operator which induces a metric(Connes' distance) on the state space. We generalize such a Dirac operator devised by A. Dimakis et al, whose Connes' distance recovers the linear distance on a 1D lattice, into 2D lattice. This Dirac operator being "naturally" defined has the so-called "local eigenvalue property" and induces Euclidean distance on this 2D lattice. This kind of Dirac operator can be generalized into any higher dimensional lattices.
Pythagoras' Theorem on a 2D-Lattice from a "Natural" Dirac Operator and Connes' Distance Formula
Dai, J; Dai, Jian; Song, Xing-Chang
2001-01-01
One of the key ingredients of A. Connes' noncommutative geometry is a generalized Dirac operator which induces a metric(Connes' distance) on the state space. We generalize such a Dirac operator devised by A. Dimakis et al, whose Connes' distance recovers the linear distance on a 1D lattice, into 2D lattice. This Dirac operator being "naturally" defined has the so-called "local eigenvalue property" and induces Euclidean distance on this 2D lattice. This kind of Dirac operator can be generalized into any higher dimensional lattices.
H. Stachel, Professor A Way to Geometry Through Descriptive Geometry
Stachel, Hellmuth
motions in [9]. The correspondence be- tween non-Euclidean differential geometry and the geometryH. Stachel, Professor A Way to Geometry Through Descriptive Geometry Vienna University of geometry and on my contributions to Descriptive Geometry education. Descriptive Geometry in Austria
Digit ratio (2D:4D) in Klinefelter's syndrome.
Manning, J T; Kilduff, L P; Trivers, R
2013-01-01
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
Numerically robust geometry engine for compound solid geometries
NASA Astrophysics Data System (ADS)
Vlachoudis, V.; Sinuela-Pastor, D.
2014-06-01
Monte Carlo programs heavily rely on a fast and numerically robust solid geometry engines. However the success of solid modeling, depends on facilities for specifying and editing parameterized models through a user-friendly graphical front-end. Such a user interface has to be fast enough in order to be interactive for 2D and/or 3D displays, but at the same time numerically robust in order to display possible modeling errors at real time that could be critical for the simulation. The graphical user interface "flair"(1) for FLUKA(2,3) currently employs such an engine where special emphasis has been given on being fast and numerically robust. The numerically robustness is achieved by a novel method of estimating the floating precision of the operations, which dynamically adapts all the decision operations accordingly. Moreover a predictive caching mechanism is ensuring that logical errors in the geometry description are found online, without compromising the processing time by checking all regions.
Differential CYP 2D6 Metabolism Alters Primaquine Pharmacokinetics.
Potter, Brittney M J; Xie, Lisa H; Vuong, Chau; Zhang, Jing; Zhang, Ping; Duan, Dehui; Luong, Thu-Lan T; Bandara Herath, H M T; Dhammika Nanayakkara, N P; Tekwani, Babu L; Walker, Larry A; Nolan, Christina K; Sciotti, Richard J; Zottig, Victor E; Smith, Philip L; Paris, Robert M; Read, Lisa T; Li, Qigui; Pybus, Brandon S; Sousa, Jason C; Reichard, Gregory A; Marcsisin, Sean R
2015-04-01
Primaquine (PQ) metabolism by the cytochrome P450 (CYP) 2D family of enzymes is required for antimalarial activity in both humans (2D6) and mice (2D). Human CYP 2D6 is highly polymorphic, and decreased CYP 2D6 enzyme activity has been linked to decreased PQ antimalarial activity. Despite the importance of CYP 2D metabolism in PQ efficacy, the exact role that these enzymes play in PQ metabolism and pharmacokinetics has not been extensively studied in vivo. In this study, a series of PQ pharmacokinetic experiments were conducted in mice with differential CYP 2D metabolism characteristics, including wild-type (WT), CYP 2D knockout (KO), and humanized CYP 2D6 (KO/knock-in [KO/KI]) mice. Plasma and liver pharmacokinetic profiles from a single PQ dose (20 mg/kg of body weight) differed significantly among the strains for PQ and carboxy-PQ. Additionally, due to the suspected role of phenolic metabolites in PQ efficacy, these were probed using reference standards. Levels of phenolic metabolites were highest in mice capable of metabolizing CYP 2D6 substrates (WT and KO/KI 2D6 mice). PQ phenolic metabolites were present in different quantities in the two strains, illustrating species-specific differences in PQ metabolism between the human and mouse enzymes. Taking the data together, this report furthers understanding of PQ pharmacokinetics in the context of differential CYP 2D metabolism and has important implications for PQ administration in humans with different levels of CYP 2D6 enzyme activity. PMID:25645856
Functional Characterization of a First Avian Cytochrome P450 of the CYP2D Subfamily (CYP2D49)
Yang, Qi; Chen, Qingmei; Deng, Yiqun
2012-01-01
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. PMID:22675558
The Hartle-Hawking wave function in 2d causal set quantum gravity
Lisa Glaser; Sumati Surya
2014-11-13
We define the Hartle-Hawking no-boundary wave function for causal set quantum gravity over the discrete analogs of spacelike hypersurfaces. Using Markov Chain Monte Carlo and numerical integration methods we analyse this wave function in non perturbative 2d causal set quantum gravity. Our results provide new insights into the role of quantum gravity in the observable universe. We find that non-manifold contributions to the Hartle-Hawking wave function can play a significant role. These discrete geometries exhibit a rapid spatial expansion with respect to the proper time and also possess a spatial homogeneity consistent with our current understanding of the observable universe.
Sigle, Daniel O.; Mertens, Jan; Herrmann, Lars O.; Bowman, Richard W.; Ithurria, Sandrine; Dubertret, Benoit; Shi, Yumeng; Yang, Hui Ying; Tserkezis, Christos; Aizpurua, Javier; Baumberg, Jeremy J.
2014-12-17
.; Chang, M.-T.; Lin, C.-T.; Chang, K.-D.; Yu, Y.- C.; Wang, J. T.-W.; Chang, C.-S.; Li, L.-J.; et al. Synthesis of Large-Area MoS2 Atomic Layers with Chemical Vapor Deposition. Adv. Mater. 2012, 24, 2320–2325. (33) Lin, Y.-C.; Zhang, W.; Huang, J... this geometry allows for simple placement of ultrathin spacer materials into the gap and hence to create stable and well defined junctions with intriguing materials properties (Fig. 1a). Since the discovery of graphene and a range of other 2- dimensional (2D...
NSDL National Science Digital Library
Geometry and Topology is "a fully refereed international journal dealing with all aspects of geometry and topology and their applications." The publisher, Geometry & Topology Publications (GTP), is a non-profit organization based in the Mathematics Department of the University of Warwick at Coventry, UK. Visitors can browse the journal, available free of charge electronically, or search by keyword or author. The moderate collection within the Geometry and Topology Monographs series includes research monographs and refereed conference proceedings.
John Stillwell
\\u000a Surprisingly, the geometry of curved surfaces throws light on the geometry of the plane. More than 2000 years after Euclid\\u000a formulated axioms for plane geometry, differential geometry showed that the parallel axiom does not follow from the other axioms of Euclid. It had long been hoped that the parallel axiom followed from the others, but no proof had ever been
Jorge Stolfi
1987-01-01
Oriented projective geometry is a model for geometric computation that combines the elegance of classical projective geometry with the ability to talk about oriented lines and planes, signed angles, line segments, convex figures, and many other concepts that cannot be defined within the classical version. Classical projective geometry is the implicit framework of many geometric computations, since it underlies the
Algebraic Geometry Jean Gallier
Gallier, Jean
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 2 Dimension, Local Theory, Projective Geometry 69 2.1 Dimension TheoryAlgebraic Geometry Jean Gallier and Stephen S. Shatz Department of Computer and Information, 2011 #12;2 #12;Contents 1 Elementary Algebraic Geometry 7 1.1 History and Problems
Algebraic Geometry Jean Gallier
Gallier, Jean
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 2 Dimension, Local Theory, Projective Geometry 67 2.1 Dimension TheoryAlgebraic Geometry Jean Gallier and Stephen S. Shatz Department of Computer and Information #12;2 #12;Contents 1 Elementary Algebraic Geometry 5 1.1 History and Problems
TRIANGLES IN HYPERBOLIC GEOMETRY
LAURA VALAAS
This paper derives the Law of Cosines, Law of Sines, and the Pythagorean Theorem for triangles in Hyperbolic Geometry. The Poincar e model for Hyperbolic Geometry is used. In order to accomplish this the paper reviews Inversion in Hyperbolic Geometry, Radical Axes and Powers of circles and expressions for hyperbolic cosine, hyperbolic sine, and hyperbolic tangent. A brief history of
Spectral Geometry Bruno Iochum
Paris-Sud XI, Université de
Spectral Geometry Bruno Iochum Aix-Marseille Université, CNRS UMR 7332, CPT, 13288 Marseille France Abstract The goal of these lectures is to present some fundamentals of noncommutative geometry looking primary objects defined for manifolds will be generalized to reach the level of noncommutative geometry
NSDL National Science Digital Library
Levy, Silvio
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.
3-D/2-D registration by integrating 2-D information in 3-D.
Tomazevic, Dejan; Likar, Bostjan; Pernus, Franjo
2006-01-01
In image-guided therapy, high-quality preoperative images serve for planning and simulation, and intraoperatively as "background", onto which models of surgical instruments or radiation beams are projected. The link between a preoperative image and intraoperative physical space of the patient is established by image-to-patient registration. In this paper, we present a novel 3-D/2-D registration method. First, a 3-D image is reconstructed from a few 2-D X-ray images and next, the preoperative 3-D image is brought into the best possible spatial correspondence with the reconstructed image by optimizing a similarity measure (SM). Because the quality of the reconstructed image is generally low, we introduce a novel SM, which is able to cope with low image quality as well as with different imaging modalities. The novel 3-D/2-D registration method has been evaluated and compared to the gradient-based method (GBM) using standardized evaluation methodology and publicly available 3-D computed tomography (CT), 3-D rotational X-ray (3DRX), and magnetic resonance (MR) and 2-D X-ray images of two spine phantoms, for which gold standard registrations were known. For each of the 3DRX, CT, or MR images and each set of X-ray images, 1600 registrations were performed from starting positions, defined as the mean target registration error (mTRE), randomly generated and uniformly distributed in the interval of 0-20 mm around the gold standard. The capture range was defined as the distance from gold standard for which the final TRE was less than 2 mm in at least 95% of all cases. In terms of success rate, as the function of initial misalignment and capture range the proposed method outperformed the GBM. TREs of the novel method and the GBM were approximately the same. For the registration of 3DRX and CT images to X-ray images as few as 2-3 X-ray views were sufficient to obtain approximately 0.4 mm TREs, 7-9 mm capture range, and 80%-90% of successful registrations. To obtain similar results for MR to X-ray registrations, an image, reconstructed from at least 11 X-ray images was required. Reconstructions from more than 11 images had no effect on the registration results. PMID:16398411
Original article Impact of geometry and viewing angle
WÃ¼rtz, Rolf P.
of increasing the number of syndromes from 10 to 14 as compared to an earlier study. Second, we include a sideOriginal article Impact of geometry and viewing angle on classification accuracy of 2D based demonstrated to be effective in a small number of syndromes. In this paper we investigate several aspects
Proper time is stochastic time in 2d quantum gravity
J. Ambjorn; R. Loll; Y. Watabiki; W. Westra; S. Zohren
2009-11-21
We show that proper time, when defined in the quantum theory of 2d gravity, becomes identical to the stochastic time associated with the stochastic quantization of space. This observation was first made by Kawai and collaborators in the context of 2d Euclidean quantum gravity, but the relation is even simpler and more transparent in he context of 2d gravity formulated in the framework of CDT (causal dynamical triangulations).
Efficient 2D cartoon production with the TOON platform
TITUS ZAHARIA; OLFA TRIKI; FRANÇOISE PRÊTEUX; OLIVIER MARRE
Abstract : -This work has been carried out within the framework of the so-called TOON project, supported by the French National Agency for Valorization of Research,. The TOON platform proposes aunified framework for automating the 2D cartoon production chain involving 2D\\/3D reconstruction, registration and animation capabilities. Key-Words: - Virtual characters, 2D\\/3D reconstruction, registration, MPEG-4 bone-based animation, cartoon production. ,,,,,,,,,,,
3-D Ray-tracing and 2-D Fokker-Planck Simulations of Radiofrequency Application to Tokamak Plasmas
A. Cardinali; F. Paoletti; S. Bernabei
1999-05-01
A state of the art numerical tool has been developed to simulate the propagation and the absorption of coexisting different types of waves in a tokamak geometry. The code includes a numerical solution of the three-dimensional (R, Z, {Phi}) toroidal wave equation for the electric field of the different waves in the WKBJ approximation. At each step of integration, the two-dimensional (v{sub {parallel}}, v{sub {perpendicular}}) Fokker-Planck equation is solved in the presence of quasilinear diffusion coefficients. The electron Landau damping of the waves is modeled taking into account the interaction of the wave electric fields with the quasilinearly modified distribution function. Consistently, the code calculates the radial profiles of non-inductively generated current densities, the transmitted power traces and the total power damping curves. Synergistic effects among the different type of waves (e.g., lower hybrid and ion Bernstein waves) are studied through the separation of the contributions of the single wave from the effects due to their coexistence.
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
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.
MEF2D overexpression contributes to the progression of osteosarcoma.
Yu, Haichi; Sun, Honghui; Bai, Yunshen; Han, Jinhua; Liu, Guomin; Liu, Yi; Zhang, Nan
2015-06-01
The underlying molecular pathogenesis of osteosarcoma remains poorly understood. The transcription factor MEF2D promotes the survival of various types of cells and functions as an oncogene in liver cancer. However, its potential contribution to osteosarcoma has not been explored. In this study, we investigated MEF2D expression and function in osteosarcoma, finding that MEF2D elevation in osteosarcoma clinical specimens was associated with patients' poor prognosis. MEF2D suppression was shown to decrease the proliferation of osteosarcoma cells, while forced expression of MEF2D was able to promote the proliferation of normal bone fibroblast. Notably, MEF2D silencing abolished osteosarcoma tumorigenicity in an animal model. Mechanistic investigations revealed that MEF2D silencing triggered G2-M arrest in osteosarcoma cells by suppressing RPRM and CDKN1A. miR-144 was found to suppress the expression of MEF2D in osteosarcoma cells. Collectively, our results demonstrated that MEF2D is a candidate oncogene for osteosarcoma and a potential molecular target for cancer therapy. PMID:25814384
Quasar Clustering and Spacetime Geometry
NASA Astrophysics Data System (ADS)
Popowski, Piotr A.; Weinberg, David H.; Ryden, Barbara S.; Osmer, Patrick S.
1998-05-01
The non-Euclidean geometry of spacetime induces an anisotropy in the apparent correlation function of high-redshift objects, such as quasars, if redshifts and angles are converted to distances in ``naive'' Euclidean fashion. The degree of angular distortion depends on cosmological parameters, especially on the cosmological constant ?, so this effect can constrain ? independent of any assumptions about the evolution of luminosities, sizes, or clustering. We examine the prospects for distinguishing between low-density (?0 = 0.1-0.4) cosmological models with flat and open space geometry using the large quasar samples anticipated from the Two Degree Field Survey (2dF) and the Sloan Digital Sky Survey (SDSS). Along the way, we derive a number of results that are useful for studies of the quasar correlation function. In particular, we show that even these large quasar surveys are likely to reside in the ``sparse sampling'' regime for correlation function measurements, so that the statistical fluctuations in measurements are simply the Poisson fluctuations in the observed numbers of pairs. As a result, (1) one can devise a simple maximum likelihood scheme for estimating clustering parameters, (2) one can generate Monte Carlo realizations of correlation function measurements without specifying high-order correlation functions or creating artificial quasar distributions, and (3) for a fixed number of quasars, a deeper survey over a smaller area has greater statistical power than a shallow, large-area survey. If the quasar correlation length is equal to the value implied by recent (quite uncertain) estimates, then the 2dF and SDSS samples can provide clear discrimination between flat and open geometries for ?0 <= 0.2 but only marginal discrimination for ?0 = 0.4. Clear discrimination is possible for ?0 = 0.4 if the true quasar correlation length is a factor of 2 larger, and a high-density survey of 30,000 quasars in 200 deg2 would provide clear discrimination even for the lower correlation length. Detection of quasar clustering anisotropy would confirm the cosmological spacetime curvature that is a fundamental prediction of general relativity.
Communication: Determining the lowest-energy isomer of Au8: 2D, or not 2D
NASA Astrophysics Data System (ADS)
Hansen, Jared A.; Piecuch, Piotr; Levine, Benjamin G.
2013-09-01
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 Møller-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 5d106s1 valence and 5s25p6 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.
2D to 3D to 2D Dimensionality Crossovers in Thin BSCCO Films
NASA Astrophysics Data System (ADS)
Williams, Gary A.
2003-03-01
With increasing temperature the superfluid fraction in very thin BSCCO films undergoes a series of dimensionality crossovers. At low temperatures the strong anisotropy causes the thermal excitations to be 2D pancake-antipancake pairs in uncoupled layers. At higher temperatures where the c-axis correlation length becomes larger than a layer there is a crossover to 3D vortex loops. These are initially elliptical, but as the 3D Tc is approached they become more circular as the anisotropy scales away, as modeled by Shenoy and Chattopadhyay [1]. Close to Tc when the correlation length becomes comparable to the film thickness there is a further crossover to a 2D Kosterlitz-Thouless transition, with a drop of the superfluid fraction to zero at T_KT which can be of the order of 1 K below T_c. Good agreement with this model is found for experiments on thin BSCCO 2212 films [2]. 1. S. R. Shenoy and B. Chattopadhyay, Phys. Rev. B 51, 9129 (1995). 2. K. Osborn et al., cond-mat/0204417.
Functional characterization of CYP2D6 enhancer polymorphisms.
Wang, Danxin; Papp, Audrey C; Sun, Xiaochun
2015-03-15
CYP2D6 metabolizes nearly 25% of clinically used drugs. Genetic polymorphisms cause large inter-individual variability in CYP2D6 enzyme activity and are currently used as biomarker to predict CYP2D6 metabolizer phenotype. Previously, we had identified a region 115 kb downstream of CYP2D6 as enhancer for CYP2D6, containing two completely linked single nucleotide polymorphisms (SNPs), rs133333 and rs5758550, associated with enhanced transcription. However, the enhancer effect on CYP2D6 expression, and the causative variant, remained to be ascertained. To characterize the CYP2D6 enhancer element, we applied chromatin conformation capture combined with the next-generation sequencing (4C assays) and chromatin immunoprecipitation with P300 antibody, in HepG2 and human primary culture hepatocytes. The results confirmed the role of the previously identified enhancer region in CYP2D6 expression, expanding the number of candidate variants to three highly linked SNPs (rs133333, rs5758550 and rs4822082). Among these, only rs5758550 demonstrated regulating enhancer activity in a reporter gene assay. Use of clustered regularly interspaced short palindromic repeats mediated genome editing in HepG2 cells targeting suspected enhancer regions decreased CYP2D6 mRNA expression by 70%, only upon deletion of the rs5758550 region. These results demonstrate robust effects of both the enhancer element and SNP rs5758550 on CYP2D6 expression, supporting consideration of rs5758550 for CYP2D6 genotyping panels to yield more accurate phenotype prediction. PMID:25381333
NASA Astrophysics Data System (ADS)
Chae, Dongho; Constantin, Peter; Wu, Jiahong
2014-09-01
We give an example of a well posed, finite energy, 2D incompressible active scalar equation with the same scaling as the surface quasi-geostrophic equation and prove that it can produce finite time singularities. In spite of its simplicity, this seems to be the first such example. Further, we construct explicit solutions of the 2D Boussinesq equations whose gradients grow exponentially in time for all time. In addition, we introduce a variant of the 2D Boussinesq equations which is perhaps a more faithful companion of the 3D axisymmetric Euler equations than the usual 2D Boussinesq equations.
A shading pipeline for 2D animation techniques HEDLENA BEZERRA
-by- frame animation. The complete system provides a flexible framework for designing and generating new styles of 2D/3D animations. 4. References [Johnson] Johnson, Scott F. "Lumo: Illumination for CelA shading pipeline for 2D animation techniques HEDLENA BEZERRA 1 , LUIZ VELHO 2 , BRUNO FEIJÓ 1 1
Integrating Mobile Multimedia into Textbooks: 2D Barcodes
ERIC Educational Resources Information Center
Uluyol, Celebi; Agca, R. Kagan
2012-01-01
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…
Novel 2-D photonic bandgap structure for microstrip lines
Vesna Radisic; Yongxi Qian; Roberto Coccioli; Tatsuo Itoh
1998-01-01
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
Observer-based boundary control for 2D Burgers equation
Efe, Mehmet Ã?nder
equation (PDE) set ut 'o (uÃ?9)u0m92 u with u being 2)/1 vector function is described as the 2D BurgersObserver-based boundary control for 2D Burgers equation Mehmet OÂ¨ nder Efe TOBB University Burgers equation has extensively been considered as a benchmark problem by flow control researchers
Concepts and Methods of 2D Infrared Spectroscopy
NASA Astrophysics Data System (ADS)
Hamm, Peter; Zanni, Martin
2011-02-01
1. Introduction; 2. Designing multiple pulse experiments; 3. Mukamelian or perturbative expansion of the density matrix; 4. Basics of 2D IR spectroscopy; 5. Polarization control; 6. Molecular couplings; 7. 2D IR lineshapes; 8. Dynamic cross peaks; 9. Experimental designs, data collection and processing; 10. Simple simulation strategies; 11. Pulse sequence design: some examples; Appendices; References; Index.
A 2D Human Body Model Dressed in Eigen Clothing
Black, Michael J.
A 2D Human Body Model Dressed in Eigen Clothing Peng Guan Oren Freifeld Michael J. Black estimation of people in monocular images are widely studied. Two-dimensional mod- els of the human body. The resulting generative model captures realistic human forms in monocular images and is used to infer 2D body
AnisWave2D: User's Guide to the 2d Anisotropic Finite-DifferenceCode
Toomey, Aoife
2005-01-06
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.
Developing Mobile BIM/2D Barcode-Based Automated Facility Management System
Chen, Yen-Pei
2014-01-01
Facility management (FM) has become an important topic in research on the operation and maintenance phase. Managing the work of FM effectively is extremely difficult owing to the variety of environments. One of the difficulties is the performance of two-dimensional (2D) graphics when depicting facilities. Building information modeling (BIM) uses precise geometry and relevant data to support the facilities depicted in three-dimensional (3D) object-oriented computer-aided design (CAD). This paper proposes a new and practical methodology with application to FM that uses an integrated 2D barcode and the BIM approach. Using 2D barcode and BIM technologies, this study proposes a mobile automated BIM-based facility management (BIMFM) system for FM staff in the operation and maintenance phase. The mobile automated BIMFM system is then applied in a selected case study of a commercial building project in Taiwan to verify the proposed methodology and demonstrate its effectiveness in FM practice. The combined results demonstrate that a BIMFM-like system can be an effective mobile automated FM tool. The advantage of the mobile automated BIMFM system lies not only in improving FM work efficiency for the FM staff but also in facilitating FM updates and transfers in the BIM environment. PMID:25250373
Developing mobile BIM/2D barcode-based automated facility management system.
Lin, Yu-Cheng; Su, Yu-Chih; Chen, Yen-Pei
2014-01-01
Facility management (FM) has become an important topic in research on the operation and maintenance phase. Managing the work of FM effectively is extremely difficult owing to the variety of environments. One of the difficulties is the performance of two-dimensional (2D) graphics when depicting facilities. Building information modeling (BIM) uses precise geometry and relevant data to support the facilities depicted in three-dimensional (3D) object-oriented computer-aided design (CAD). This paper proposes a new and practical methodology with application to FM that uses an integrated 2D barcode and the BIM approach. Using 2D barcode and BIM technologies, this study proposes a mobile automated BIM-based facility management (BIMFM) system for FM staff in the operation and maintenance phase. The mobile automated BIMFM system is then applied in a selected case study of a commercial building project in Taiwan to verify the proposed methodology and demonstrate its effectiveness in FM practice. The combined results demonstrate that a BIMFM-like system can be an effective mobile automated FM tool. The advantage of the mobile automated BIMFM system lies not only in improving FM work efficiency for the FM staff but also in facilitating FM updates and transfers in the BIM environment. PMID:25250373
NSDL National Science Digital Library
Provided by David Eppstein, professor of Information and Computer Science at the University of California-Irvine, the Geometry Junkyard is a metasite covering classical geometry theory and current research in the area of computation geometry. A few examples of the many topics included in the Geometry Junkyard are: combination geometry, fractals, multi-dimensional geometry, and open problems (most of which are illustrated with diagrams). Dr. Eppstein's thoughtful selection of links point users to numerous discussions and solutions to problems; in addition, he has added several pages on topics not well covered (My Own Junk), and has highlighted newly added material (New Junk). This site is more of a gold mine than a junkyard, based on the vast amount of information provided and the fun spin placed on many of the topics.
Feng, Feng; Wu, Junchi; Wu, Changzheng; Xie, Yi
2015-02-01
Recent advancements in regulating the electrical behavior of 2D inorganic nanomaterials for energy applications are highlighted by C. Z. Wu and co-workers on page 654. Due to the synergetic advantages of their superior electrical conductivity and excellent reaction activity, highly conductive 2D nanomaterials open up prospects for enhancing performance in electrochemical applications towards energy conversion and storage. PMID:25656145
NKG2D CAR T-cell therapy inhibits the growth of NKG2D ligand heterogeneous tumors.
Spear, Paul; Barber, Amorette; Rynda-Apple, Agnieszka; Sentman, Charles L
2013-07-01
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
Developments in special geometry
Mohaupt, Thomas
2011-01-01
We review the special geometry of N = 2 supersymmetric vector and hypermultiplets with emphasis on recent developments and applications. A new formulation of the local c-map based on the Hesse potential and special real coordinates is presented. Other recent developments include the Euclidean version of special geometry, and generalizations of special geometry to non-supersymmetric theories. As applications we disucss the proof that the local r-map and c-map preserve geodesic completeness, and the construction of four- and five-dimensional static solutions through dimensional reduction over time. The shared features of the real, complex and quaternionic version of special geometry are stressed throughout.
Developments in special geometry
Thomas Mohaupt; Owen Vaughan
2012-01-19
We review the special geometry of N = 2 supersymmetric vector and hypermultiplets with emphasis on recent developments and applications. A new formulation of the local c-map based on the Hesse potential and special real coordinates is presented. Other recent developments include the Euclidean version of special geometry, and generalizations of special geometry to non-supersymmetric theories. As applications we disucss the proof that the local r-map and c-map preserve geodesic completeness, and the construction of four- and five-dimensional static solutions through dimensional reduction over time. The shared features of the real, complex and quaternionic version of special geometry are stressed throughout.
Developments in special geometry
NASA Astrophysics Data System (ADS)
Mohaupt, Thomas; Vaughan, Owen
2012-02-01
We review the special geometry of Script N = 2 supersymmetric vector and hypermultiplets with emphasis on recent developments and applications. A new formulation of the local c-map based on the Hesse potential and special real coordinates is presented. Other recent developments include the Euclidean version of special geometry, and generalizations of special geometry to non-supersymmetric theories. As applications we disucss the proof that the local r-map and c-map preserve geodesic completeness, and the construction of four- and five-dimensional static solutions through dimensional reduction over time. The shared features of the real, complex and quaternionic version of special geometry are stressed throughout.
Geometry of Thin Nematic Elastomer Sheets
NASA Astrophysics Data System (ADS)
Aharoni, Hillel; Sharon, Eran; Kupferman, Raz
2014-12-01
A thin sheet of nematic elastomer attains 3D configurations depending on the nematic director field upon heating. In this Letter, we describe the intrinsic geometry of such a sheet and derive an expression for the metric induced by general nematic director fields. Furthermore, we investigate the reverse problem of constructing a director field that induces a specified 2D geometry. We provide an explicit recipe for how to construct any surface of revolution using this method. Finally, we show that by inscribing a director field gradient across the sheet's thickness, one can obtain a nontrivial hyperbolic reference curvature tensor, which together with the prescription of a reference metric allows dictation of actual configurations for a thin sheet of nematic elastomer.
2D vs. 3D mammography observer study
NASA Astrophysics Data System (ADS)
Fernandez, James Reza F.; Hovanessian-Larsen, Linda; Liu, Brent
2011-03-01
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.
Almost but not quite 2D, Non-linear Bayesian Inversion of CSEM Data
NASA Astrophysics Data System (ADS)
Ray, A.; Key, K.; Bodin, T.
2013-12-01
The geophysical inverse problem can be elegantly stated in a Bayesian framework where a probability distribution can be viewed as a statement of information regarding a random variable. After all, the goal of geophysical inversion is to provide information on the random variables of interest - physical properties of the earth's subsurface. However, though it may be simple to postulate, a practical difficulty of fully non-linear Bayesian inversion is the computer time required to adequately sample the model space and extract the information we seek. As a consequence, in geophysical problems where evaluation of a full 2D/3D forward model is computationally expensive, such as marine controlled source electromagnetic (CSEM) mapping of the resistivity of seafloor oil and gas reservoirs, Bayesian studies have largely been conducted with 1D forward models. While the 1D approximation is indeed appropriate for exploration targets with planar geometry and geological stratification, it only provides a limited, site-specific idea of uncertainty in resistivity with depth. In this work, we extend our fully non-linear 1D Bayesian inversion to a 2D model framework, without requiring the usual regularization of model resistivities in the horizontal or vertical directions used to stabilize quasi-2D inversions. In our approach, we use the reversible jump Markov-chain Monte-Carlo (RJ-MCMC) or trans-dimensional method and parameterize the subsurface in a 2D plane with Voronoi cells. The method is trans-dimensional in that the number of cells required to parameterize the subsurface is variable, and the cells dynamically move around and multiply or combine as demanded by the data being inverted. This approach allows us to expand our uncertainty analysis of resistivity at depth to more than a single site location, allowing for interactions between model resistivities at different horizontal locations along a traverse over an exploration target. While the model is parameterized in 2D, we efficiently evaluate the forward response using 1D profiles extracted from the model at the common-midpoints of the EM source-receiver pairs. Since the 1D approximation is locally valid at different midpoint locations, the computation time is far lower than is required by a full 2D or 3D simulation. We have applied this method to both synthetic and real CSEM survey data from the Scarborough gas field on the Northwest shelf of Australia, resulting in a spatially variable quantification of resistivity and its uncertainty in 2D. This Bayesian approach results in a large database of 2D models that comprise a posterior probability distribution, which we can subset to test various hypotheses about the range of model structures compatible with the data. For example, we can subset the model distributions to examine the hypothesis that a resistive reservoir extends overs a certain spatial extent. Depending on how this conditions other parts of the model space, light can be shed on the geological viability of the hypothesis. Since tackling spatially variable uncertainty and trade-offs in 2D and 3D is a challenging research problem, the insights gained from this work may prove valuable for subsequent full 2D and 3D Bayesian inversions.
Practical Algorithm For Computing The 2-D Arithmetic Fourier Transform
NASA Astrophysics Data System (ADS)
Reed, Irving S.; Choi, Y. Y.; Yu, Xiaoli
1989-05-01
Recently, Tufts and Sadasiv [10] exposed a method for computing the coefficients of a Fourier series of a periodic function using the Mobius inversion of series. They called this method of analysis the Arithmetic Fourier Transform(AFT). The advantage of the AFT over the FN 1' is that this method of Fourier analysis needs only addition operations except for multiplications by scale factors at one stage of the computation. The disadvantage of the AFT as they expressed it originally is that it could be used effectively only to compute finite Fourier coefficients of a real even function. To remedy this the AFT developed in [10] is extended in [11] to compute the Fourier coefficients of both the even and odd components of a periodic function. In this paper, the improved AFT [11] is extended to a two-dimensional(2-D) Arithmetic Fourier Transform for calculating the Fourier Transform of two-dimensional discrete signals. This new algorithm is based on both the number-theoretic method of Mobius inversion of double series and the complex conjugate property of Fourier coefficients. The advantage of this algorithm over the conventional 2-D FFT is that the corner-turning problem needed in a conventional 2-D Discrete Fourier Transform(DFT) can be avoided. Therefore, this new 2-D algorithm is readily suitable for VLSI implementation as a parallel architecture. Comparing the operations of 2-D AFT of a MxM 2-D data array with the conventional 2-D FFT, the number of multiplications is significantly reduced from (2log2M)M2 to (9/4)M2. Hence, this new algorithm is faster than the FFT algorithm. Finally, two simulation results of this new 2-D AFT algorithm for 2-D artificial and real images are given in this paper.
Seven-degree-of-freedom, quantum scattering dynamics study of the H2D++H2 reaction
NASA Astrophysics Data System (ADS)
Wang, Dunyou; Xie, Zhen; Bowman, Joel M.
2010-02-01
A quantum scattering dynamics, time-dependent wavepacket propagation method is applied to study the reaction of H2D++H2?H3++HD on the Xie-Braams-Bowman potential energy surface. The reduced-dimensional, seven-degree-of-freedom approach is employed in this calculation by fixing one Jacobi and one torsion angle related to H2D+ at the lowest saddle point geometry of D2d on the potential energy surface. Initial state selected reaction probabilities are presented for various initial rovibrational states. The ground state reaction probability shows no threshold for this reaction, in other words, this reaction can occur without an activation barrier. The vibrational excitation shows that the stretching motion of H+-HD only has a small effect on the reaction probability; the vibrational excitation of HD in H2D+ hinders the reactivity. By contrast, rotational excitation of H+-HD greatly enhances the reactivity with the reaction probability increased double or triple at high rotational states compared to the ground state. Reactive resonances, seen in all the initial state selected reaction probabilities, are also found in the integral cross section for the ground state of H2D+ and H2. The thermal rate coefficient is also calculated and is found to be in semiquantitative agreement with experiment; however, quantum scattering approaches including more degrees of freedom, especially including all the angles, are necessary to study this reaction in the future.
Dynamic unfolding of multilayers: 2D numerical approach and application to turbidites in SW Portugal
NASA Astrophysics Data System (ADS)
Lechmann, S. M.; Schmalholz, S. M.; Burg, J.-P.; Marques, F. O.
2010-10-01
Numerical algorithms for two-dimensional (2D) ductile multilayer folding are used (1) to unfold synthetically generated multilayer folds and natural multilayer folds in turbidites on the SW coast of Portugal and (2) to test how 2D ductile multilayer folding may generate collapsed hinges. A series of dynamic retro-deformation experiments with different viscosity ratios, rheological flow laws, boundary conditions and initial geometries were able to restore digitized, natural multilayer folds to flat layers, except one particular collapsed hinge with closed limbs (i.e. no matrix material left between limbs). Consistently, 2D forward simulations of ductile multilayer folding produced always omega-shaped hinges with matrix material remaining stuffed between limbs. These numerical results suggested that 2D reverse ductile unfolding cannot retro-deform the fully closed, collapsed hinge. Having observed that one limb of this collapsed fold is ruptured, with a measured gap of about 4.9 m, additional calculations were made with implementation of this amount of stretching. Results were not more satisfactory. Since omega-shaped folds exist in other places in the field area, we concluded that in this specific case shales were likely squeezed out from the hinge in the third dimension, parallel to the fold axis. Dynamic retro-deformations indicate that the effective viscosity ratio between inter-layered quartzwackes and shales was between 25 and 100 during folding. They further point out where 3D flow and possibly fracturing were effective during folding. This work demonstrates the constructive feedback between numerical tests and field data and that dynamic retro-deformation offers rheological constraints that geometric retro-deformation of geological sections cannot provide.
Cluster algebras in scattering amplitudes with special 2D kinematics
NASA Astrophysics Data System (ADS)
Torres, Marcus A. C.
2014-02-01
We study the cluster algebra of the kinematic configuration space of an -particle scattering amplitude restricted to the special 2D kinematics. We found that the -point two-loop MHV remainder function in special 2D kinematics depends on a selection of the -coordinates that are part of a special structure of the cluster algebra related to snake triangulations of polygons. This structure forms a necklace of hypercube beads in the corresponding Stasheff polytope. Furthermore at , the cluster algebra and the selection of the -coordinates in special 2D kinematics replicates the cluster algebra and the selection of -coordinates of the two-loop MHV amplitude in 4D kinematics.
Bose-einstein condensation in quasi-2D trapped gases
Petrov; Holzmann; Shlyapnikov
2000-03-20
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 T
Azimuthal Reorientation of Pentacene upon 2D Condensation
NASA Astrophysics Data System (ADS)
Sun, L. D.; Gall, J.; Weidlinger, G.; Liu, C. Y.; Denk, M.; Zeppenfeld, P.
2013-03-01
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.
Comparison of 2D and 3D gamma analyses
Pulliam, Kiley B.; Huang, Jessie Y.; Howell, Rebecca M.; Followill, David; Bosca, Ryan; O’Daniel, Jennifer; Kry, Stephen F.
2014-01-01
Purpose: As clinics begin to use 3D metrics for intensity-modulated radiation therapy (IMRT) quality assurance, it must be noted that these metrics will often produce results different from those produced by their 2D counterparts. 3D and 2D gamma analyses would be expected to produce different values, in part because of the different search space available. In the present investigation, the authors compared the results of 2D and 3D gamma analysis (where both datasets were generated in the same manner) for clinical treatment plans. Methods: Fifty IMRT plans were selected from the authors’ clinical database, and recalculated using Monte Carlo. Treatment planning system-calculated (“evaluated dose distributions”) and Monte Carlo-recalculated (“reference dose distributions”) dose distributions were compared using 2D and 3D gamma analysis. This analysis was performed using a variety of dose-difference (5%, 3%, 2%, and 1%) and distance-to-agreement (5, 3, 2, and 1 mm) acceptance criteria, low-dose thresholds (5%, 10%, and 15% of the prescription dose), and data grid sizes (1.0, 1.5, and 3.0 mm). Each comparison was evaluated to determine the average 2D and 3D gamma, lower 95th percentile gamma value, and percentage of pixels passing gamma. Results: The average gamma, lower 95th percentile gamma value, and percentage of passing pixels for each acceptance criterion demonstrated better agreement for 3D than for 2D analysis for every plan comparison. The average difference in the percentage of passing pixels between the 2D and 3D analyses with no low-dose threshold ranged from 0.9% to 2.1%. Similarly, using a low-dose threshold resulted in a difference between the mean 2D and 3D results, ranging from 0.8% to 1.5%. The authors observed no appreciable differences in gamma with changes in the data density (constant difference: 0.8% for 2D vs 3D). Conclusions: The authors found that 3D gamma analysis resulted in up to 2.9% more pixels passing than 2D analysis. It must be noted that clinical 2D versus 3D datasets may have additional differences—for example, if 2D measurements are made with a different dosimeter than 3D measurements. Factors such as inherent dosimeter differences may be an important additional consideration to the extra dimension of available data that was evaluated in this study. PMID:24506601
Comparison of 2D and 3D gamma analyses
Pulliam, Kiley B.; Huang, Jessie Y.; Howell, Rebecca M.; Followill, David; Kry, Stephen F., E-mail: sfkry@mdanderson.org [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center and The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030 (United States); Bosca, Ryan [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center and The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030 (United States)] [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center and The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030 (United States); O’Daniel, Jennifer [Department of Radiation Oncology, Duke University, Durham, North Carolina 27705 (United States)] [Department of Radiation Oncology, Duke University, Durham, North Carolina 27705 (United States)
2014-02-15
Purpose: As clinics begin to use 3D metrics for intensity-modulated radiation therapy (IMRT) quality assurance, it must be noted that these metrics will often produce results different from those produced by their 2D counterparts. 3D and 2D gamma analyses would be expected to produce different values, in part because of the different search space available. In the present investigation, the authors compared the results of 2D and 3D gamma analysis (where both datasets were generated in the same manner) for clinical treatment plans. Methods: Fifty IMRT plans were selected from the authors’ clinical database, and recalculated using Monte Carlo. Treatment planning system-calculated (“evaluated dose distributions”) and Monte Carlo-recalculated (“reference dose distributions”) dose distributions were compared using 2D and 3D gamma analysis. This analysis was performed using a variety of dose-difference (5%, 3%, 2%, and 1%) and distance-to-agreement (5, 3, 2, and 1 mm) acceptance criteria, low-dose thresholds (5%, 10%, and 15% of the prescription dose), and data grid sizes (1.0, 1.5, and 3.0 mm). Each comparison was evaluated to determine the average 2D and 3D gamma, lower 95th percentile gamma value, and percentage of pixels passing gamma. Results: The average gamma, lower 95th percentile gamma value, and percentage of passing pixels for each acceptance criterion demonstrated better agreement for 3D than for 2D analysis for every plan comparison. The average difference in the percentage of passing pixels between the 2D and 3D analyses with no low-dose threshold ranged from 0.9% to 2.1%. Similarly, using a low-dose threshold resulted in a difference between the mean 2D and 3D results, ranging from 0.8% to 1.5%. The authors observed no appreciable differences in gamma with changes in the data density (constant difference: 0.8% for 2D vs 3D). Conclusions: The authors found that 3D gamma analysis resulted in up to 2.9% more pixels passing than 2D analysis. It must be noted that clinical 2D versus 3D datasets may have additional differences—for example, if 2D measurements are made with a different dosimeter than 3D measurements. Factors such as inherent dosimeter differences may be an important additional consideration to the extra dimension of available data that was evaluated in this study.
Geometry Here, Geometry There, Geomerty is EVERYWHERE!
NSDL National Science Digital Library
Miss Tiller
2012-02-05
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 ...
Interactive Geometry Dictionary: Areas in Geometry
NSDL National Science Digital Library
2011-01-01
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.
Julien, Pierre Y.
APPENDIX I I.1 CASC2D-SED Sub-routines List--------------------------------------------------------------------------I-2 I.2 CASC2D-SED Code----------------------------------------------------------------------------------------I-4 I.3 CASC2D-SED Input/Output Files
Continental rifting to seafloor spreading: 2D and 3D numerical modeling
NASA Astrophysics Data System (ADS)
Liao, Jie; Gerya, Taras
2014-05-01
Two topics related with continental extension is studied by using numerical modeling methods: (1) Lithospheric mantle stratification changes dynamics of craton extension (2D modeling) and (2) Initial lithospheric rheological structure influences the incipient geometry of the seafloor spreading (3D modeling). (Topic 1) Lithospheric mantle stratification is a common feature in cratonic areas which has been demonstrated by geophysical and geochemical studies. The influence of lithospheric mantle stratification during craton evolution remains poorly understood. We use a 2D thermo-mechanical coupled numerical model to study the influence of stratified lithospheric mantle on craton extension. A rheologically weak layer representing hydrated and/or metasomatized composition is implemented in the lithospheric mantle. Our results show that the weak mantle layer changes the dynamics of lithospheric extension by enhancing the deformation of the overlying mantle and crust and inhibiting deformation of the underlying mantle. Modeling results are compared with North China and North Atlantic cratons. Our work indicates that although the presence of a weak layer may not be sufficient to initiate craton deformation, it enhances deformation by lowering the required extensional plate boundary force. (Topic 2) The process from continental rifting to seafloor spreading is an important step in the Wilson Cycle. Since the rifting to spreading is a continuous process, understanding the inheritance of continental rifting in seafloor spreading is crucial to study the incipient geometry (on a map view) of the oceanic ridge and remains a big challenge. Large extension strain is required to simulate the rifting and spreading processes. Oceanic ridge has a 3D geometry on a map view in nature, which requires 3D studies. Therefore, we employ the three-dimensional numerical modeling method to study this problem. The initial lithospheric rheological structure and the perturbation geometry are two key parameters that we investigated. The modeling results show that the continental rifting history affects the incipient geometry of the seafloor spreading, leading to (1) single straight oceanic ridge, (2) overlapping oceanic ridge and (3) curved oceanic ridge.
Geometry Professionalized for Teachers.
ERIC Educational Resources Information Center
Christofferson, Halbert Carl
Written in 1933, this book grew out of the author's concern that college matehmatics sequences of the day, although appropriate in algebra preparation, did not adequately prepare teachers of geometry. This book describes a course intended to remedy this by providing for both a comprehensive study of geometry as an axiomatically defined structure…
Projective Geometry Image Analysis
Paris-Sud XI, Université de
Projective Geometry for Image Analysis A Tutorial given at ISPRS, Vienna, July 1996 Roger Mohr A Hierarchy of Geometries 25 4.1 From Projective to Affine Space and Bill Triggs GRAVIR, project MOVI INRIA, 655 avenue de l'Europe F-38330 Montbonnot St Martin France E
ERIC Educational Resources Information Center
Lyublinskaya, Irina; Funsch, Dan
2012-01-01
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…
Geometry of multihadron production
Bjorken, J.D.
1994-10-01
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.
Euclidean Geometry via Programming.
ERIC Educational Resources Information Center
Filimonov, Rossen; Kreith, Kurt
1992-01-01
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…
Advanced Review Geometry optimization
Schlegel, H. Bernhard
, line searches, trust radius, and rational function optimization techniques. Single-ended and double electronic structure packages have a selection of geometry op- timization algorithms. By discussing cases for optimizing equilibrium geometries38 and TSs.39 POTENTIAL ENERGY SURFACES The structure
Some links between turtle geometry and analytic geometry
Neil C. Rowe
1985-01-01
The computer language LOGO facilitates the teaching of analytic geometry and calculus from the notion of curvature, through its ‘turtle geometry’ facility [2]. We provide some theoretical basis for finding turtle geometry equivalents of familiar curves in analytic geometry, and vice versa, by some simple methods which apparently have not been noticed previously. In particular, we study turtle geometry programs
Frolov, Vadim A; Escalada, Artur; Akimov, Sergey A; Shnyrova, Anna V
2015-01-01
Cellular membranes define the functional geometry of intracellular space. Formation of new membrane compartments and maintenance of complex organelles require division and disconnection of cellular membranes, a process termed membrane fission. Peripheral membrane proteins generally control membrane remodeling during fission. Local membrane stresses, reflecting molecular geometry of membrane-interacting parts of these proteins, sum up to produce the key membrane geometries of fission: the saddle-shaped neck and hour-glass hemifission intermediate. Here, we review the fundamental principles behind the translation of molecular geometry into membrane shape and topology during fission. We emphasize the central role the membrane insertion of specialized protein domains plays in orchestrating fission in vitro and in cells. We further compare individual to synergistic action of the membrane insertion during fission mediated by individual protein species, proteins complexes or membrane domains. Finally, we describe how local geometry of fission intermediates defines the functional design of the protein complexes catalyzing fission of cellular membranes. PMID:25062896
U. Gran; J. Gutowski; G. Papadopoulos; D. Roest
2006-12-14
We review some aspects of the spinorial geometry approach to the classification of supersymmetric solutions of supergravity theories. In particular, we explain how spinorial geometry can be used to express the Killing spinor equations in terms of a linear system for the fluxes and the geometry of spacetime. The solutions of this linear system express some of the fluxes in terms of the spacetime geometry and determine the conditions on the spacetime geometry imposed by supersymmetry. We also present some of the recent applications like the classification of maximally supersymmetric G-backgrounds in IIB, this includes the most general pp-wave solution preserving 1/2 supersymmetry, and the classification of N=31 backgrounds in ten and eleven dimensions.
Van der Waals heterostructures: Stacked 2D materials shed light
NASA Astrophysics Data System (ADS)
Wang, Xiaomu; Xia, Fengnian
2015-03-01
A powerful strategy to leverage and combine the optoelectronic characteristics of different 2D materials is to stack them into vertical van der Waals heterostructures. This approach is now used to realize efficient light-emitting devices.
Reconstruction-based 3D/2D image registration.
Tomazevic, Dejan; Likar, Bostjan; Pernus, Franjo
2005-01-01
In this paper we present a novel 3D/2D registration method, where first, a 3D image is reconstructed from a few 2D X-ray images and next, the preoperative 3D image is brought into the best possible spatial correspondence with the reconstructed image by optimizing a similarity measure. Because the quality of the reconstructed image is generally low, we introduce a novel asymmetric mutual information similarity measure, which is able to cope with low image quality as well as with different imaging modalities. The novel 3D/2D registration method has been evaluated using standardized evaluation methodology and publicly available 3D CT, 3DRX, and MR and 2D X-ray images of two spine phantoms, for which gold standard registrations were known. In terms of robustness, reliability and capture range the proposed method outperformed the gradient-based method and the method based on digitally reconstructed radiographs (DRRs). PMID:16685964
Collective excitations in 2D hard-disc fluid.
Huerta, Adrian; Bryk, Taras; Trokhymchuk, Andrij
2015-07-01
Collective dynamics of a two-dimensional (2D) hard-disc fluid was studied by molecular dynamics simulations in the range of packing fractions that covers states up to the freezing. Some striking features concerning collective excitations in this system were observed. In particular, the short-wavelength shear waves while being absent at low packing fractions were observed in the range of high packing fractions, just before the freezing transition in a 2D hard-disc fluid. In contrast, the so-called "positive sound dispersion" typically observed in dense Lennard-Jones-like fluids, was not detected for the 2D hard-disc fluid. The ratio of specific heats in the 2D hard-disc fluid shows a monotonic increase with density approaching the freezing, resembling in this way the similar behavior in the vicinity of the Widom line in the case of supercritical fluids. PMID:25595625
STOCHASTIC 2-D NAVIER-STOKES EQUATION WITH ARTIFICIAL COMPRESSIBILITY
Menaldi, Jose-Luis
STOCHASTIC 2-D NAVIER-STOKES EQUATION WITH ARTIFICIAL COMPRESSIBILITY Navier-Stokes equation wi* *th artificial compressibility. The main results of this work operator and the nonlinearity. 1. Introduction The stochastic Navier-Stokes
Stability Enhancement by Boundary Control in 2D Channel Flow
Balogh, Andras - Department of Mathematics, University of Texas
- tuators and sensors only at the wall. The control of channel flow was previously considered by Speyer incompressible fluid flow in a 2D channel. Great advances have been made on this topic by Speyer and coworkers
Global Solutions to a Logarithmically Regularized 2 D Euler Equation
NASA Astrophysics Data System (ADS)
Dong, Hongjie; Li, Dong
2015-03-01
We construct global solutions to a logarithmically modified 2D Euler vorticity equation. Our main tool is a new logarithm interpolation inequality which exploits the L ?--conservation of the vorticity.
A 2d spray model with gyroscopic effects. Ayman Moussa
Sueur, Franck
A 2d spray model with gyroscopic effects. Ayman Moussa , Franck Sueur , December 15, 2011 Abstract-type equation and an Euler-type equation: the fluid acts on the dispersed phase through a gyroscopic force
Imaging with a 2D Transducer Hybrid Array
Ken Erikson; Jason Stockwell; Allen Hairston; Gary Rich; John Marciniec; Lee Walter; Kristin Clark; Tim White
Imaging with fully populated 2D arrays using acoustical lenses in the low MHz frequency range offers the potential for high resolution, real-time, 3D volume imaging together with low power and low cost. A 2D composite piezoelectric receiver array bonded directly to a large custom integrated circuit was discussed1 at the 23rd International Symposium on Acoustical Imaging. This 128 × 128
Dissipation in Turbulent Solutions of 2-D Euler
Gregory L. Eyink
2000-01-01
We establish local balance equations for smooth functions of the vorticity in\\u000athe DiPerna-Majda weak solutions of 2D incompressible Euler, analogous to the\\u000abalance proved by Duchon and Robert for kinetic energy in 3D. The anomalous\\u000aterm or defect distribution therein corresponds to the ``enstrophy cascade'' of\\u000a2D turbulence. It is used to define a rather natural notion of ``dissipative
Bose-Einstein Condensation in Quasi2D Trapped Gases
D. S. Petrov; M. Holzmann; G. V. Shlyapnikov
2000-01-01
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 T
Phylogenetic tree construction based on 2D graphical representation
NASA Astrophysics Data System (ADS)
Liao, Bo; Shan, Xinzhou; Zhu, Wen; Li, Renfa
2006-04-01
A new approach based on the two-dimensional (2D) graphical representation of the whole genome sequence [Bo Liao, Chem. Phys. Lett., 401(2005) 196.] is proposed to analyze the phylogenetic relationships of genomes. The evolutionary distances are obtained through measuring the differences among the 2D curves. The fuzzy theory is used to construct phylogenetic tree. The phylogenetic relationships of H5N1 avian influenza virus illustrate the utility of our approach.
Momentum Jumps in Quasi-2D Ballistic Systems
Daniela Dragoman
2004-10-07
It is shown that the depopulation of magnetoelectric subbands of ballistic electrons in quasi-2D systems, due to an increased magnetic field parallel to the 2D electron gas plane, produces a momentum jump of the ballistic electrons in a direction transverse to the magnetic field. The present technological achievements allow the observation of this new phenomenon, which can be used to implement qubit states or electron switches
Relaxation of 2D Turbulence to Vortex Crystals
C. F. Driscoll; D. A. Schecter; D. Z. Jin; D. H. E. Dubin; K. S. Fine; A. C. Cass
1999-01-01
A magnetically confined electron column evolves in (r,theta) as an essentially inviscid, incompressible 2D fluid with a single sign of vorticity. Turbulent initial states with 50-100 vortices relax due to vortex merger and filamentation, in general agreement with recent scaling theories. However, this relaxation is sometimes halted when 3-20 vortices ``anneal'' into a fixed pattern, or ``vortex crystal.'' 2D vortex-in-cell
Relaxation of 2D turbulence of vortex crystals
C. F. Driscoll; D. A. Schecter; D. Z. Jin; D. H. E. Dubin; K. S. Fine; A. C. Cass
1999-01-01
A magnetically confined electron column evolves in (r, ?) as an essentially inviscid, incompressible 2D fluid with a single sign of vorticity. Turbulent initial states with 50–100 vortices relax due to vortex merger and filamentation, in general agreement with recent scaling theories. However, this relaxation is sometimes halted when 3–20 vortices “anneal” into a fixed pattern, or “vortex crystal”. 2D
Implementation of 2D\\/3D Transformation for Clothing Panel
Xinrong Hu; Yan Bai; Shuqin Cui; Zhongmin Deng
2009-01-01
2D\\/3D transformation for clothing panel is one of most important steps for virtual clothing. And vector mesh generation is one of the basic tasks that complete 2D\\/3D transformation of clothing panel images and virtual clothing designs. Based on the classical methods of generating meshes, an algorithm for generating vector meshes which is suitable for garment panel images was presented. The
Generating a 2D Representation of a Complex Data Structure
NASA Technical Reports Server (NTRS)
James, Mark
2006-01-01
A computer program, designed to assist in the development and debugging of other software, generates a two-dimensional (2D) representation of a possibly complex n-dimensional (where n is an integer >2) data structure or abstract rank-n object in that other software. The nature of the 2D representation is such that it can be displayed on a non-graphical output device and distributed by non-graphical means.
On some 2D orthogonal q-polynomials
Mourad E. H. Ismail; Ruiming Zhang
2014-11-18
We introduce two q-analogues of the 2D-Hermite polynomials which are functions of two complex variables. We derive explicit formulas, orthogonality relations, raising and lowering operator relations, generating functions, and Rodrigues formulas for both families. We also introduce a q-2D analogue of the disk polynomials (Zernike polynomials) and derive similar formulas for them as well including evaluating certain connection coefficients. Some of the generating functions may be related to Rogers-Ramanujan type identities.
2dF grows up: Echidna for the AAT
Andrew McGrath; Sam Barden; Stan Miziarski; William Rambold; Greg Smith
2008-01-01
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
Analyse de Fourier: 2D DFT (FFT) Frank NIELSEN
Nielsen, Frank
INF555 TD7 Analyse de Fourier: 2D DFT (FFT) Frank NIELSEN nielsen@lix.polytechnique.fr 3 Novembre 2010 1 Prise en main de la FFT 2D Compiler le programme fftINF555.java qui implÂ´emente la FFT discr^ues `a la prÂ´ecision finie des nombres flottants (au format IEEE 754). Appliquez la FFT puis son inverse
Analyse de Fourier: 2D DFT (FFT) Frank NIELSEN
Nielsen, Frank
INF555 TD7 Analyse de Fourier: 2D DFT (FFT) Frank NIELSEN nielsen@lix.polytechnique.fr 2 Novembre 2011 1 Prise en main de la FFT 2D Compiler le programme fftINF555.java qui implÂ´emente la FFT discr^ues `a la prÂ´ecision finie des nombres flottants (au format IEEE 754). Appliquez la FFT puis son inverse
841 P.2d 990 Page 1 4 Cal.4th 389, 841 P.2d 990, 14 Cal.Rptr.2d 470
Kammen, Daniel M.
, 841 P.2d 990) Briefs and Other Related Documents Johnson v. BradleyCal. 1992.ROSS JOHNSON et al for partial public funding of campaigns for city elective offices. An action to enjoin implementation of Prop. 73, prohibited use of public money to fund political campaigns in local as well as statewide
Induced geometry from disformal transformation
Fang-Fang Yuan; Peng Huang
2015-02-08
In this note, we use the disformal transformation to induce a geometry from the manifold which is originally Riemannian. The new geometry obtained here can be considered as a generalization of Weyl integrable geometry. Based on these results, we further propose a geometry which is naturally a generalization of Weyl geometry.
Geometrie im Internet Wolfgang Rath
Stachel, Hellmuth
Geometrie im Internet Wolfgang Rath Institut fÃ¼r Geometrie, TU Wien rath@geometrie.tuwien.ac.at http://www.geometrie.tuwien.ac.at/rath Version 1999-11-15 #12;Geometrie im Internet - Wolfgang Rath......................................................................................... 5 1.1 SCHNELLER EINSTIEG INS INTERNET
The Bifurcation Approach Hyperbolic Geometry
Ungar, Abraham A.
to which Euclidean geometry bifurcates into two mutually dual branches of hyperbolic geometry in its transition to nonÂ Euclidean geometry. One of the two resulting branches turns out to be the standard of the geometry generate, that alÂ lows Euclidean and hyperbolic geometry to be unified in terms of analogies
Flavors of Geometry MSRI Publications
Kapovich, Misha
of non-Euclidean geometry, that is, a geometry that discards one of Euclid's axioms. Einstein and Minkowski found in non-Euclidean geometry a This work was supported in part by The Geometry Center of the twentieth century every serious student of mathematics and physics studied non-Euclidean geometry. This has
Amoeboid motion in confined geometry
Hao Wu; Marine Thiébaut; Wei-Fan Hu; Alexander Farutin; Salima Rafaï; Ming-Chih Lai; Philippe Peyla; Chaouqi Misbah
2015-02-13
Cells of the immune system, as well as cancer cells, migrating in confined environment of tissues undergo frequent shape changes (described as amoeboid motion) that enable them to move forward through these porous media without the assistance of adhesion sites. In other words, they perform amoeboid swimming (AS) while using extracellular matrices and cells of tissues as support. We introduce a simple model of AS in a confined geometry solved by means of 2D numerical simulations. We find that confinement promotes AS, unless being so strong that it restricts shape change amplitude. A straight AS trajectory in the channel is found to be unstable, and ample lateral excursions of the swimmer prevail. For weak confinement, these excursions are symmetric, while they become asymmetric at stronger confinement, whereby the swimmer is located closer to one of the two walls. This is a spontaneous symmetry-breaking bifurcation. We find that there exists an optimal confinement for migration. We provide numerical results as well as scaling laws. This study raises the question of the relevance of these scenarios to complex situations encountered in vivo.
NSDL National Science Digital Library
2007-12-12
This website focuses on Native American use of the physical, proportional geometry that originates from the simple circle. Aimed at 4th to 9th grade teachers, the site is divided into four sections: foundations, anthropology, designs, and education. It was selected by Britannica.com, February 2000, as a best Internet site. Other keywords: geometric shapes, geometric constructions, proportional geometry, proportional constants, polygons, hexagons, equilateral triangles, dodecagons, squares, octagons, connect the dot, art, square roots, irrational numbers, non-random geometry. (Includes about 25 relevant website links and 50 published references)
An automated pipeline to screen membrane protein 2D crystallization.
Kim, Changki; Vink, Martin; Hu, Minghui; Love, James; Stokes, David L; Ubarretxena-Belandia, Iban
2010-06-01
Electron crystallography relies on electron cryomicroscopy of two-dimensional (2D) crystals and is particularly well suited for studying the structure of membrane proteins in their native lipid bilayer environment. To obtain 2D crystals from purified membrane proteins, the detergent in a protein-lipid-detergent ternary mixture must be removed, generally by dialysis, under conditions favoring reconstitution into proteoliposomes and formation of well-ordered lattices. To identify these conditions a wide range of parameters such as pH, lipid composition, lipid-to-protein ratio, ionic strength and ligands must be screened in a procedure involving four steps: crystallization, specimen preparation for electron microscopy, image acquisition, and evaluation. Traditionally, these steps have been carried out manually and, as a result, the scope of 2D crystallization trials has been limited. We have therefore developed an automated pipeline to screen the formation of 2D crystals. We employed a 96-well dialysis block for reconstitution of the target protein over a wide range of conditions designed to promote crystallization. A 96-position magnetic platform and a liquid handling robot were used to prepare negatively stained specimens in parallel. Robotic grid insertion into the electron microscope and computerized image acquisition ensures rapid evaluation of the crystallization screen. To date, 38 2D crystallization screens have been conducted for 15 different membrane proteins, totaling over 3000 individual crystallization experiments. Three of these proteins have yielded diffracting 2D crystals. Our automated pipeline outperforms traditional 2D crystallization methods in terms of throughput and reproducibility. PMID:20349145
ERIC Educational Resources Information Center
Emenaker, Charles E.
1999-01-01
Describes a sixth-grade interdisciplinary geometry unit based on Charles Dickens's "A Christmas Carol". Focuses on finding area, volume, and perimeter, and working with estimation, decimals, and fractions in the context of making gingerbread houses. (ASK)
Functional Differential Geometry
Sussman, Gerald Jay
2005-02-02
Differential geometry is deceptively simple. It is surprisingly easyto get the right answer with unclear and informal symbol manipulation.To address this problem we use computer programs to communicate aprecise understanding ...
NSDL National Science Digital Library
Brown, Kevin
"Informal notes" by Kevin Brown on geometry: constructing the heptadecagon, what mirrors do, the golden pentagon, the grazing goat and the lune, Napoleon's theorem, chess boards, Diophantine geodesic boxes, Zeno's mice and the logarithmic spiral, and many more.
ERIC Educational Resources Information Center
Potter, Gretchen
1976-01-01
After a unit on Euclidean geometry which stresses both the development of intuition and the use of deductive methods, non-Euclidean concepts are introduced by having students read and consider science fiction stories. (SD)
Yuri A. Rylov
2000-01-01
The proper Euclidean geometry is considered to be metric space and described\\u000ain terms of only metric and finite metric subspaces (sigma-immanent\\u000adescription). Constructing the geometry, one does not use topology and\\u000atopological properties. For instance, the straight, passing through points A\\u000aand B, is defined as a set of such points R that the area S(A,B,R) of the\\u000atriangle
Quantum Computation as Geometry
Michael A. Nielsen; Mark R. Dowling; Mile Gu; Andrew C. Doherty
2006-03-21
Quantum computers hold great promise, but it remains a challenge to find efficient quantum circuits that solve interesting computational problems. We show that finding optimal quantum circuits is essentially equivalent to finding the shortest path between two points in a certain curved geometry. By recasting the problem of finding quantum circuits as a geometric problem, we open up the possibility of using the mathematical techniques of Riemannian geometry to suggest new quantum algorithms, or to prove limitations on the power of quantum computers.
José Natário
\\u000a In this chapter we discuss the non-Euclidean geometry of curved surfaces, using the sphere as our primary example. We find\\u000a that all the information about the geometry of the surface is contained in the expression for the distance between two nearby\\u000a points in some coordinate system, called the metric. For example, the distance between two distant points can be found
Sparse radar imaging using 2D compressed sensing
NASA Astrophysics Data System (ADS)
Hou, Qingkai; Liu, Yang; Chen, Zengping; Su, Shaoying
2014-10-01
Radar imaging is an ill-posed linear inverse problem and compressed sensing (CS) has been proved to have tremendous potential in this field. This paper surveys the theory of radar imaging and a conclusion is drawn that the processing of ISAR imaging can be denoted mathematically as a problem of 2D sparse decomposition. Based on CS, we propose a novel measuring strategy for ISAR imaging radar and utilize random sub-sampling in both range and azimuth dimensions, which will reduce the amount of sampling data tremendously. In order to handle 2D reconstructing problem, the ordinary solution is converting the 2D problem into 1D by Kronecker product, which will increase the size of dictionary and computational cost sharply. In this paper, we introduce the 2D-SL0 algorithm into the reconstruction of imaging. It is proved that 2D-SL0 can achieve equivalent result as other 1D reconstructing methods, but the computational complexity and memory usage is reduced significantly. Moreover, we will state the results of simulating experiments and prove the effectiveness and feasibility of our method.
Powerful Cherenkov oscillators with 2D distributed feedback
NASA Astrophysics Data System (ADS)
Ginzburg, N. S.; Zaslavskii, V. Yu.; Ilyakov, E. V.; Kulagin, I. S.; Malkin, A. M.; Peskov, N. Yu.; Sergeev, A. S.
2011-12-01
The feasibility of using 2D distributed feedback based on 2D planar and coaxial Bragg structures for generating spatially coherent radiation from rectilinear ribbon and tubular electron beams is studied. One-section and sectional Cherenkov masers are analyzed. In the former design, a 2D Bragg structure acts as a resonator and a periodic slow-wave system simultaneously. In the latter (sectional) design, radiation is synchronized in a 2D Bragg structure that is placed at the cathode end of the interaction space and couples longitudinal and transverse (azimuthal) wave flows. The wave is amplified by the electron beam mainly in the fairly long middle section. The output (collector) part contains a standard 1D Bragg structure that partially reflects the amplified radiation toward the cathode and closes the feedback circuit. It is shown that dissipation introduced into the 2D Bragg structure of the sectional design makes it possible to increase one of the transverse sizes of the system to ˜103 wavelengths with the energy exchange efficiency and one-frequency masing mode stability remaining the same. With such an overdimension, the millimeter-wave radiation integral power may reach a gigawatt level.
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.
NASA Astrophysics Data System (ADS)
McAteer, R. T. J.
2013-06-01
When Mandelbrot, the father of modern fractal geometry, made this seemingly obvious statement he was trying to show that we should move out of our comfortable Euclidean space and adopt a fractal approach to geometry. The concepts and mathematical tools of fractal geometry provides insight into natural physical systems that Euclidean tools cannot do. The benet from applying fractal geometry to studies of Self-Organized Criticality (SOC) are even greater. SOC and fractal geometry share concepts of dynamic n-body interactions, apparent non-predictability, self-similarity, and an approach to global statistics in space and time that make these two areas into naturally paired research techniques. Further, the iterative generation techniques used in both SOC models and in fractals mean they share common features and common problems. This chapter explores the strong historical connections between fractal geometry and SOC from both a mathematical and conceptual understanding, explores modern day interactions between these two topics, and discusses how this is likely to evolve into an even stronger link in the near future.
Simulation of 2D and 3Dcavity flow using the Lattice Boltzmann Method
NASA Astrophysics Data System (ADS)
Wang, Lubing; Qian, Yuehong; Zhao, Peng; Zhang, Dandan
2007-11-01
The lid-driven cavity flow is a well-known benchmark problem for fluid simulations. Due to the simplicity of the cavity geometry, numerical simulation is relatively easy and straightforward; in addition, it retains a rich flow physics manifested by the vortex structures in the center and corner regions varying with the Reynolds number (Re). Therefore, it has been studied extensively by different simulation approaches. But still there are some aspects which are not agreed upon and need further investigation. All simulations are conducted by using the Lattice Boltzmann Method in fine grid systems and with parallel algorithm. First, some detailed results are presented and compared with classic solutions found in literatures for code validation. Then the transition process from laminar to turbulent flow in 2D and 3D situations are conducted by increasing the Reynolds number; detailed results for time-velocity histories, and relative Fourier power spectra, phase diagram are given. Some accuracy estimation will be also included.
The role of the Beltrami parametrization of complex structures in 2-d Free Conformal Field Theory
Serge Lazzarini
2005-09-30
This talk gives a review on how complex geometry and a Lagrangian formulation of 2-d conformal field theory are deeply related. In particular, how the use of the Beltrami parametrization of complex structures on a compact Riemann surface fits perfectly with the celebrated locality principle of field theory, the latter requiring the use infinite dimensional spaces. It also allows a direct application of the local index theorem for families of elliptic operators due to J.-M. Bismut, H. Gillet and C. Soul\\'{e}. The link between determinant line bundles equipped with the Quillen\\'s metric and the so-called holomorphic factorization property will be addressed in the case of free spin $j$ b-c systems or more generally of free fields with values sections of a holomorphic vector bundles over a compact Riemann surface.
2D full wave modeling for a synthetic Doppler backscattering diagnostic
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
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.
An Integrative Model of Excitation Driven Fluid Flow in a 2D Uterine Channel
NASA Astrophysics Data System (ADS)
Maggio, Charles; Fauci, Lisa; Chrispell, John
2009-11-01
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.
Automatic Detection of 2D and 3D Lung Nodules in Chest Spiral CT Scans.
El-Baz, Ayman; Elnakib, Ahmed; Abou El-Ghar, Mohamed; Gimel'farb, Georgy; Falk, Robert; Farag, Aly
2013-01-01
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. PMID:23509444
Toward an Efficient Icing CFD Process Using an Interactive Software Toolkit: Smagglce 2D
NASA Technical Reports Server (NTRS)
Vickerman, Mary B.; Choo, Yung K.; Schilling, Herbert W.; Baez, Marivell; Braun, Donald C.; Cotton, Barbara J.
2001-01-01
Two-dimensional CID analysis for iced airfoils can be a labor-intensive task. The software toolkit SmaggIce 2D is being developed to help streamline the CID process and provide the unique features needed for icing. When complete, it will include a combination of partially automated and fully interactive tools for all aspects of the tasks leading up to the flow analysis: geometry preparation, domain decomposition. block boundary demoralization. gridding, and linking with a flow solver. It also includes tools to perform ice shape characterization, an important aid in determining the relationship between ice characteristics and their effects on aerodynamic performance. Completed tools, work-in-progress, and planned features of the software toolkit are presented here.
Toward an Efficient Icing CFD Process Using an Interactive Software Toolkit--SmaggIce 2D
NASA Technical Reports Server (NTRS)
Vickerman, Mary B.; Choo, Yung K.; Schilling, Herbert W.; Baez, Marivell; Braun, Donald C.; Cotton, Barbara J.
2002-01-01
Two-dimensional CFD analysis for iced airfoils can be a labor-intensive task. The software toolkit SmaggIce 2D is being developed to help streamline the CFD process and provide the unique features needed for icing. When complete, it will include a combination of partially automated and fully interactive tools for all aspects of the tasks leading up to the flow analysis: geometry preparation, domain decomposition, block boundary discretization. gridding, and linking with a flow solver. It also includes tools to perform ice shape characterization, an important aid in determining the relationship between ice characteristics and their effects on aerodynamic performance. Completed tools, work-in-progress, and planned features of the software toolkit are presented here.
Study of the mechanical behavior of a 2-D carbon-carbon composite
NASA Technical Reports Server (NTRS)
Avery, W. B.; Herakovich, C. T.
1987-01-01
The out-of-plane fracture of a 2-D carbon-carbon composite was observed and characterized to gain an understanding of the factors influencing the stress distribution in such a laminate. Finite element analyses of a two-ply carbon-carbon composite under in-plane, out-of-plane, and thermal loading were performed. Under in-plane loading all components of stress were strong functions of geometry. Additionally, large thermal stresses were predicted. Out-of-plane tensile tests revealed that failure was interlaminar, and that cracks propagated along the fiber-matrix interface. An elasticity solution was utilized to analyze an orthotropic fiber in an isotropic matrix under uniform thermal load. The analysis reveals that the stress distributions in a transversely orthotropic fiber are radically different than those predicted assuming the fiber to be transversely isotropic.
ARC2D - EFFICIENT SOLUTION METHODS FOR THE NAVIER-STOKES EQUATIONS (CRAY VERSION)
NASA Technical Reports Server (NTRS)
Pulliam, T. H.
1994-01-01
ARC2D is a computational fluid dynamics program developed at the NASA Ames Research Center specifically for airfoil computations. The program uses implicit finite-difference techniques to solve two-dimensional Euler equations and thin layer Navier-Stokes equations. It is based on the Beam and Warming implicit approximate factorization algorithm in generalized coordinates. The methods are either time accurate or accelerated non-time accurate steady state schemes. The evolution of the solution through time is physically realistic; good solution accuracy is dependent on mesh spacing and boundary conditions. The mathematical development of ARC2D begins with the strong conservation law form of the two-dimensional Navier-Stokes equations in Cartesian coordinates, which admits shock capturing. The Navier-Stokes equations can be transformed from Cartesian coordinates to generalized curvilinear coordinates in a manner that permits one computational code to serve a wide variety of physical geometries and grid systems. ARC2D includes an algebraic mixing length model to approximate the effect of turbulence. In cases of high Reynolds number viscous flows, thin layer approximation can be applied. ARC2D allows for a variety of solutions to stability boundaries, such as those encountered in flows with shocks. The user has considerable flexibility in assigning geometry and developing grid patterns, as well as in assigning boundary conditions. However, the ARC2D model is most appropriate for attached and mildly separated boundary layers; no attempt is made to model wake regions and widely separated flows. The techniques have been successfully used for a variety of inviscid and viscous flowfield calculations. The Cray version of ARC2D is written in FORTRAN 77 for use on Cray series computers and requires approximately 5Mb memory. The program is fully vectorized. The tape includes variations for the COS and UNICOS operating systems. Also included is a sample routine for CONVEX computers to emulate Cray system time calls, which should be easy to modify for other machines as well. The standard distribution media for this version is a 9-track 1600 BPI ASCII Card Image format magnetic tape. The Cray version was developed in 1987. The IBM ES/3090 version is an IBM port of the Cray version. It is written in IBM VS FORTRAN and has the capability of executing in both vector and parallel modes on the MVS/XA operating system and in vector mode on the VM/XA operating system. Various options of the IBM VS FORTRAN compiler provide new features for the ES/3090 version, including 64-bit arithmetic and up to 2 GB of virtual addressability. The IBM ES/3090 version is available only as a 9-track, 1600 BPI IBM IEBCOPY format magnetic tape. The IBM ES/3090 version was developed in 1989. The DEC RISC ULTRIX version is a DEC port of the Cray version. It is written in FORTRAN 77 for RISC-based Digital Equipment platforms. The memory requirement is approximately 7Mb of main memory. It is available in UNIX tar format on TK50 tape cartridge. The port to DEC RISC ULTRIX was done in 1990. COS and UNICOS are trademarks and Cray is a registered trademark of Cray Research, Inc. IBM, ES/3090, VS FORTRAN, MVS/XA, and VM/XA are registered trademarks of International Business Machines. DEC and ULTRIX are registered trademarks of Digital Equipment Corporation.
ARC2D - EFFICIENT SOLUTION METHODS FOR THE NAVIER-STOKES EQUATIONS (DEC RISC ULTRIX VERSION)
NASA Technical Reports Server (NTRS)
Biyabani, S. R.
1994-01-01
ARC2D is a computational fluid dynamics program developed at the NASA Ames Research Center specifically for airfoil computations. The program uses implicit finite-difference techniques to solve two-dimensional Euler equations and thin layer Navier-Stokes equations. It is based on the Beam and Warming implicit approximate factorization algorithm in generalized coordinates. The methods are either time accurate or accelerated non-time accurate steady state schemes. The evolution of the solution through time is physically realistic; good solution accuracy is dependent on mesh spacing and boundary conditions. The mathematical development of ARC2D begins with the strong conservation law form of the two-dimensional Navier-Stokes equations in Cartesian coordinates, which admits shock capturing. The Navier-Stokes equations can be transformed from Cartesian coordinates to generalized curvilinear coordinates in a manner that permits one computational code to serve a wide variety of physical geometries and grid systems. ARC2D includes an algebraic mixing length model to approximate the effect of turbulence. In cases of high Reynolds number viscous flows, thin layer approximation can be applied. ARC2D allows for a variety of solutions to stability boundaries, such as those encountered in flows with shocks. The user has considerable flexibility in assigning geometry and developing grid patterns, as well as in assigning boundary conditions. However, the ARC2D model is most appropriate for attached and mildly separated boundary layers; no attempt is made to model wake regions and widely separated flows. The techniques have been successfully used for a variety of inviscid and viscous flowfield calculations. The Cray version of ARC2D is written in FORTRAN 77 for use on Cray series computers and requires approximately 5Mb memory. The program is fully vectorized. The tape includes variations for the COS and UNICOS operating systems. Also included is a sample routine for CONVEX computers to emulate Cray system time calls, which should be easy to modify for other machines as well. The standard distribution media for this version is a 9-track 1600 BPI ASCII Card Image format magnetic tape. The Cray version was developed in 1987. The IBM ES/3090 version is an IBM port of the Cray version. It is written in IBM VS FORTRAN and has the capability of executing in both vector and parallel modes on the MVS/XA operating system and in vector mode on the VM/XA operating system. Various options of the IBM VS FORTRAN compiler provide new features for the ES/3090 version, including 64-bit arithmetic and up to 2 GB of virtual addressability. The IBM ES/3090 version is available only as a 9-track, 1600 BPI IBM IEBCOPY format magnetic tape. The IBM ES/3090 version was developed in 1989. The DEC RISC ULTRIX version is a DEC port of the Cray version. It is written in FORTRAN 77 for RISC-based Digital Equipment platforms. The memory requirement is approximately 7Mb of main memory. It is available in UNIX tar format on TK50 tape cartridge. The port to DEC RISC ULTRIX was done in 1990. COS and UNICOS are trademarks and Cray is a registered trademark of Cray Research, Inc. IBM, ES/3090, VS FORTRAN, MVS/XA, and VM/XA are registered trademarks of International Business Machines. DEC and ULTRIX are registered trademarks of Digital Equipment Corporation.
NASA Astrophysics Data System (ADS)
Le Roux, Olivier; Cornou, Cécile; Jongmans, Denis; Schwartz, Stéphane
2012-09-01
H/V spectral ratios are regularly used for estimating the bedrock depth in 1-D like basins exhibiting smooth lateral variations. In the case of 2-D or 3-D pronounced geometries, observational and numerical studies have shown that H/V curves exhibit peculiar shapes and that the H/V frequency generally overestimates 1-D theoretical resonance frequency. To investigate the capabilities of the H/V method in complex structures, a detailed comparison between measured and 3-D-simulated ambient vibrations was performed in the small-size lower Romanche valley (French Alps), which shows significant variations in geometry, downstream and upstream the Séchilienne basin. Analysing the H/V curve characteristics, two different wave propagation modes were identified along the valley. Relying on previous geophysical investigation, a power-law relationship was derived between the bedrock depth and the H/V peak frequency, which was used for building a 3-D model of the valley geometry. Simulated and experimental H/V curves were found to exhibit quite similar features in terms of curve shape and peak frequency values, validating the 3-D structure. This good agreement also evidenced two different propagation modes in the valley: 2-D resonance in the Séchilienne basin and 1-D resonance in the external parts. This study underlines the interest of H/V curves for investigating complex basin structures.
2D growth processes: SLE and Loewner chains
Michel Bauer; Denis Bernard
2006-02-20
This review provides an introduction to two dimensional growth processes. Although it covers a variety processes such as diffusion limited aggregation, it is mostly devoted to a detailed presentation of stochastic Schramm-Loewner evolutions (SLE) which are Markov processes describing interfaces in 2D critical systems. It starts with an informal discussion, using numerical simulations, of various examples of 2D growth processes and their connections with statistical mechanics. SLE is then introduced and Schramm's argument mapping conformally invariant interfaces to SLE is explained. A substantial part of the review is devoted to reveal the deep connections between statistical mechanics and processes, and more specifically to the present context, between 2D critical systems and SLE. Some of the SLE remarkable properties are explained, as well as the tools for computing with SLE. This review has been written with the aim of filling the gap between the mathematical and the physical literatures on the subject.
Azimuthal reorientation of pentacene upon 2D condensation.
Sun, L D; Gall, J; Weidlinger, G; Liu, C Y; Denk, M; Zeppenfeld, P
2013-03-01
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
The Galaxy Power Spectrum: 2dFGRS-SDSS tension?
Shaun Cole; Ariel G. Sanchez; Stephen Wilkins
2006-11-06
Published galaxy power spectra from the 2dFGRS and SDSS are not in good agreement. We revisit this issue by analyzing both the 2dFGRS and SDSS DR5 catalogues using essentially identical technqiues. We confirm that the 2dFGRS exhibits relatively more large scale power than the SDSS, or, equivalently, SDSS has more small scale power. We demonstrate that this difference is due the r-band selected SDSS catalogue being dominated by more strongly clustered red galaxies, due to these galaxies having a stronger scale dependent bias. The power spectra of galaxies of the same rest frame colours from the two surveys match well. It is therefore important to accurately model scale dependent bias to get accurate estimates of cosmological parameters from these power spectra.
Pseudo 2D random sampling for compressed sensing MRI.
Wang, Haifeng; Liang, Dong; Ying, Leslie
2009-01-01
The paper presents a novel approach of pseudo 2D random sampling scheme for application of compressed sensing in Cartesian magnetic resonance imaging (MRI). The proposed scheme is realized by a pulse sequence program which switches the directions of phase encoding and frequency encoding during data acquisition such that both k(x) and k(y) directions can be undersampled randomly. The resulting random sampling pattern approximates the ideal but impractical 2D patterns. Both the simulation and experiment results show the proposed method is superior to the existing 1D random sampling and similar to the ideal 2D random sampling in terms of the reconstruction quality. This method can potentially improve the MR imaging speed through the application of compressed sensing in conventional MRI. PMID:19964588
Dispersion analysis and engineering of 2D plasmonic waveguides
NASA Astrophysics Data System (ADS)
Mekawey, Hosam; Ismail, Yehea; Swillam, Mohamed A.
2015-01-01
A full investigation of the low-order guided modes in a two-dimensional (2D) hollow metallic waveguide is performed. The dispersion characteristics of the 2D hollow metallic waveguides are identified and analyzed. Manipulating the dispersion is proposed by either changing the geometrical shapes from rectangular to trapezoidal waveguide or changing the material of the cladding region to TiN. The dispersion analysis of the 2D plasmonic waveguide using TiN is investigated for the first time. The effect of varying the shape parameters on the cutoff in the modes dispersion is studied. The trapezoidal shape waveguide that causes the most significant shift in the cutoff is selected and detailed dispersion analysis of its guided modes is performed. The effect of changing the plasmonic material on the dispersion curve key characteristics is also identified. Finally, the effect of shifting the cutoff on the enhanced transmission phenomena is investigated.
Microscale 2D separation systems for proteomic analysis
Xu, Xin; Liu, Ke; Fan, Z. Hugh
2012-01-01
Microscale 2D separation systems have been implemented in capillaries and microfabricated channels. They offer advantages of faster analysis, higher separation efficiency and less sample consumption than the conventional methods, such as liquid chromatography (LC) in a column and slab gel electrophoresis. In this article, we review their recent advancement, focusing on three types of platforms, including 2D capillary electrophoresis (CE), CE coupling with capillary LC, and microfluidic devices. A variety of CE and LC modes have been employed to construct 2D separation systems via sophistically designed interfaces. Coupling of different separation modes has also been realized in a number of microfluidic devices. These separation systems have been applied for the proteomic analysis of various biological samples, ranging from a single cell to tumor tissues. PMID:22462786
Secretory pathways generating immunosuppressive NKG2D ligands
Baragaño Raneros, Aroa; Suarez-Álvarez, Beatriz; López-Larrea, Carlos
2014-01-01
Natural Killer Group 2 member D (NKG2D) activating receptor, present on the surface of various immune cells, plays an important role in activating the anticancer immune response by their interaction with stress-inducible NKG2D ligands (NKG2DL) on transformed cells. However, cancer cells have developed numerous mechanisms to evade the immune system via the downregulation of NKG2DL from the cell surface, including the release of NKG2DL from the cell surface in a soluble form. Here, we review the mechanisms involved in the production of soluble NKG2DL (sNKG2DL) and the potential therapeutic strategies aiming to block the release of these immunosuppressive ligands. Therapeutically enabling the NKG2D-NKG2DL interaction would promote immunorecognition of malignant cells, thus abrogating disease progression. PMID:25050215
Conformal invariance: From Weyl to SO(2,d)
NASA Astrophysics Data System (ADS)
Faci, S.
2013-02-01
The present work deals with two different but subtilely related kinds of conformal mappings: Weyl rescaling in d > 2 dimensional spaces and SO(2,d) transformations. We express how the difference between the two can be compensated by diffeomorphic transformations. This is well known in the framework of string theory but in the particular case of d = 2 spaces. Indeed, the Polyakov formalism describes world sheets in terms of two-dimensional conformal field theory (CFT). On the other hand, Zumino had shown that a classical four-dimensional Weyl-invariant field theory restricted to live in Minkowski space leads to an SO(2,4)-invariant field theory. We extend Zumino's result to relate Weyl and SO(2,d) symmetries in arbitrary conformally flat spaces (CFS). This allows us to assert that a classical SO(2,d)-invariant field does not distinguish, at least locally, between two different d-dimensional CFSs.
2D IR Spectroscopy of Protein Conformation, Folding, and Binding
NASA Astrophysics Data System (ADS)
Jones, Kevin; Tokmakoff, Andrei; Ganim, Ziad; Lessing, Joshua; Peng, C. Sam
2011-03-01
2D IR spectroscopy is an increasingly powerful tool for investigation of protein structure and dynamics. As an ultrafast spectroscopy, it provides information on protein structure and conformational variation with high time resolution, providing a tool to study the dynamics of folding and binding. Some of the unique characteristics of 2D IR result from the powerful structure based modeling that is available for amide vibrations. This talk will cover recent examples from our group in which different forms of protein 2D IR and computational spectroscopy are used to reveal conformational heterogeneity in peptides, the folding and binding of proteins, and protein-water interactions. When combined with temperature-jump experiments, the formation and interchange of these structures is probed.
Complex 2D photonic crystals with analogue local symmetry as 12-fold quasicrystals.
Cheng, Shih-Chieh; Zhu, Xuelian; Yang, Shu
2009-09-14
We construct fourteen complex periodic two-dimensional (2D) photonic structures with different structural symmetries by arranging the small portions of a 12-fold quasicrystal on square or hexagonal lattices. The corresponding reciprocal lattices confirm that all of them demonstrate the 12-fold-like characteristics due to the analogue short-range arrangements. We then investigate their photonic bandgap properties at different dielectric contrast levels (dielectric rods in air background). Our results suggest that all structures possess analogue transverse magnetic (TM) gaps in both Si and glass photonic crystals due to the similarity of their local geometries. However, the arrangements of the basic elements, total symmetries, and the coupling between the local and the lattice symmetries have greater impact on the glass photonic crystals, which show much larger deviation of gap sizes from different structures. Furthermore, we find that the minimal dielectric contrast to achieve the TM gap in the complex lattices (dielectric-in-air) can be as low as epsilon = 1.44, whereas the inverse structures may open a 2D complete gap in silicon nitride (epsilon = 4.1). PMID:19770885
Acoustic Receptivity of a Blasius Boundary Layer with 2-D and Oblique Surface Waviness
NASA Technical Reports Server (NTRS)
King, Rudolph A.; Breuer, Kenneth S.
2000-01-01
An experimental investigation was conducted to examine acoustic receptivity and subsequent boundary-layer instability evolution for a Blasius boundary layer formed on a flat plate in the presence of two-dimensional (2-D) and oblique (3-D) surface waviness. The effect of the non-localized surface roughness geometry and acoustic wave amplitude on the receptivity process was explored. The surface roughness had a well defined wavenumber spectrum with fundamental wavenumber k (sub w). A planar downstream traveling acoustic wave was created to temporally excite the flow near the resonance frequency of an unstable eigenmode corresponding to k (sub ts) = k (sub w). The range of acoustic forcing levels, epsilon, and roughness heights, DELTA h, examined resulted in a linear dependence of receptivity coefficients; however, the larger values of the forcing combination epsilon dot DELTA h resulted in subsequent nonlinear development of the Tollmien-Schlichting (T-S) wave. This study provided the first experimental evidence of a marked increase in the receptivity coefficient with increasing obliqueness of the surface waviness in excellent agreement with theory. Detuning of the 2-D and oblique disturbances was investigated by varying the streamwise wall-roughness wavenumber a,, and measuring the T-S response. For the configuration where laminar-to-turbulent breakdown occurred, the breakdown process was found to be dominated by energy at the fundamental and harmonic frequencies, indicative of K-type breakdown.
Noninvasive estimation of 2-D pressure gradients in steady flow using ultrasound.
Olesen, Jacob; Traberg, Marie; Pihl, Michael; Jensen, Jørgen
2014-08-01
A noninvasive method for estimating 2-D pressure gradients from ultrasound vector velocity data is presented. It relies on vector velocity fields acquired using the transverse oscillation method during steady flow conditions. The pressure gradients are calculated from the velocity fields using the Navier-Stokes equations. Scans of a carotid bifurcation phantom with a 70% constriction are performed using a linear transducer connected to a scanner. The performance of the estimator is evaluated by comparing its results to those of a computational fluid dynamics model of the carotid bifurcation phantom. The geometry of the model is determined from magnetic resonance imaging. The presented study is conducted assuming steady flow using velocity data acquired at 18 frames per second. The proposed method shows pressure gradients at the constricted region from -8 kPa/m to 9 kPa/m, with a maximum bias of -7% for the axial component and -8% for the lateral component. The relative standard deviation of the estimator is 5% (axial component) and 30% (lateral component) when studying the pressure gradient across the constriction using 3 velocity frames per pressure estimate. The study shows that 2-D pressure gradients can be achieved noninvasively using ultrasound data in a constant flow environment. PMID:25073147
NASA Astrophysics Data System (ADS)
Ray, Anandaroop; Key, Kerry; Bodin, Thomas; Myer, David; Constable, Steven
2014-12-01
We apply a reversible-jump Markov chain Monte Carlo method to sample the Bayesian posterior model probability density function of 2-D seafloor resistivity as constrained by marine controlled source electromagnetic data. This density function of earth models conveys information on which parts of the model space are illuminated by the data. Whereas conventional gradient-based inversion approaches require subjective regularization choices to stabilize this highly non-linear and non-unique inverse problem and provide only a single solution with no model uncertainty information, the method we use entirely avoids model regularization. The result of our approach is an ensemble of models that can be visualized and queried to provide meaningful information about the sensitivity of the data to the subsurface, and the level of resolution of model parameters. We represent models in 2-D using a Voronoi cell parametrization. To make the 2-D problem practical, we use a source-receiver common midpoint approximation with 1-D forward modelling. Our algorithm is transdimensional and self-parametrizing where the number of resistivity cells within a 2-D depth section is variable, as are their positions and geometries. Two synthetic studies demonstrate the algorithm's use in the appraisal of a thin, segmented, resistive reservoir which makes for a challenging exploration target. As a demonstration example, we apply our method to survey data collected over the Scarborough gas field on the Northwest Australian shelf.
NASA Astrophysics Data System (ADS)
Chatterjee, Monish R.; Feng, Le
2014-02-01
An analytic examination of 3D holography under a 90° recording geometry was carried out earlier in which 2D spatial Laplace transforms were introduced in order to develop transfer functions for the scattered outputs under readout [1,2]. Thereby, the resulting reconstructed output was obtained in the 2D Laplace domain whence the spatial information would be found only by performing a 2D Laplace inversion. Laplace inversion in 2D was attempted by testing a prototype function for which the analytic result was known using two known inversion algorithms, viz., the Brancik and the Abate [2]. The results indicated notable differences in the 3D plots between the algorithms and the analytic result, and hence were somewhat inconclusive. In this paper, we take a closer look at the Brancik algorithm in order to understand better the implications of the choices of key parameters such as the real and imaginary parts of the Bromwich contour and the grid sizes of the summation operations. To assess the inversion findings, three prototype test cases are considered for which the analytic solutions are known. For specific choices of the algorithm parameters, optimal values are determined that minimize errors in general. It is found that even though errors accumulate near the edges of the grid, overall reasonably accurate inversions are possible to obtain with optimal parameter choices that are verifiable via cross-sectional views. Further work is ongoing whereby the optimized algorithm is to be applied to the 3D holography problem.
SmaggIce 2D Version 1.8: Software Toolkit Developed for Aerodynamic Simulation Over Iced Airfoils
NASA Technical Reports Server (NTRS)
Choo, Yung K.; Vickerman, Mary B.
2005-01-01
SmaggIce 2D version 1.8 is a software toolkit developed at the NASA Glenn Research Center that consists of tools for modeling the geometry of and generating the grids for clean and iced airfoils. Plans call for the completed SmaggIce 2D version 2.0 to streamline the entire aerodynamic simulation process--the characterization and modeling of ice shapes, grid generation, and flow simulation--and to be closely coupled with the public-domain application flow solver, WIND. Grid generated using version 1.8, however, can be used by other flow solvers. SmaggIce 2D will help researchers and engineers study the effects of ice accretion on airfoil performance, which is difficult to do with existing software tools because of complex ice shapes. Using SmaggIce 2D, when fully developed, to simulate flow over an iced airfoil will help to reduce the cost of performing flight and wind-tunnel tests for certifying aircraft in natural and simulated icing conditions.
NASA Astrophysics Data System (ADS)
Tønning, Erik; Polders, Daniel; Callaghan, Paul T.; Engelsen, Søren B.
2007-09-01
This paper demonstrates how the multi-linear PARAFAC model can with advantage be used to decompose 2D diffusion-relaxation correlation NMR spectra prior to 2D-Laplace inversion to the T2- D domain. The decomposition is advantageous for better interpretation of the complex correlation maps as well as for the quantification of extracted T2- D components. To demonstrate the new method seventeen mixtures of wheat flour, starch, gluten, oil and water were prepared and measured with a 300 MHz nuclear magnetic resonance (NMR) spectrometer using a pulsed gradient stimulated echo (PGSTE) pulse sequence followed by a Carr-Purcell-Meiboom-Gill (CPMG) pulse echo train. By varying the gradient strength, 2D diffusion-relaxation data were recorded for each sample. From these double exponentially decaying relaxation data the PARAFAC algorithm extracted two unique diffusion-relaxation components, explaining 99.8% of the variation in the data set. These two components were subsequently transformed to the T2- D domain using 2D-inverse Laplace transformation and quantitatively assigned to the oil and water components of the samples. The oil component was one distinct distribution with peak intensity at D = 3 × 10 -12 m 2 s -1 and T2 = 180 ms. The water component consisted of two broad populations of water molecules with diffusion coefficients and relaxation times centered around correlation pairs: D = 10 -9 m 2 s -1, T2 = 10 ms and D = 3 × 10 -13 m 2 s -1, T2 = 13 ms. Small spurious peaks observed in the inverse Laplace transformation of original complex data were effectively filtered by the PARAFAC decomposition and thus considered artefacts from the complex Laplace transformation. The oil-to-water ratio determined by PARAFAC followed by 2D-Laplace inversion was perfectly correlated with known oil-to-water ratio of the samples. The new method of using PARAFAC prior to the 2D-Laplace inversion proved to have superior potential in analysis of diffusion-relaxation spectra, as it improves not only the interpretation, but also the quantification.
An interactive 2-D power-line modeling and simulation tool
NASA Astrophysics Data System (ADS)
Hull, David; Adelman, Ross
2012-06-01
The U.S. Army Research Laboratory's Power-Line unmanned aerial vehicle (UAV) Modeling and Simulation (ARL-PLUMS) is a tool for estimating and analyzing quasi-static electric and magnetic fields due to power lines. This tool consists of an interactive 2-D graphical user interface (GUI) and a compute engine that can be used to calculate and visualize the E-Field and H-Field due to as many as seven conductors (two 3-phase circuits and a ground wire). ARL-PLUMS allows the user to set the geometry of the lines and the load conditions on those lines, and then calculate Ey, Ez, Hy, or Hz along a linear path or cutting plane, or in the form of a movie. The path can be along the ground or in the air to simulate the fields that might be observed, for example, by a robotic vehicle or a UAV. ARL-PLUMS makes several simplifying assumptions in order to allow simulations to be completed on a laptop PC interactively. In most cases, the results are excellent, providing a "90% solution" in just a few minutes of total modeling and simulation time. This paper describes the physics used by ARL-PLUMS, including the simplifying assumptions and the 2-D Method of Moments solver. Examples of electric and magnetic fields for different wire configurations, including typical 3-phase distribution and transmissions lines, are provided. Comparisons to similar results using a full 3-D model are also shown, and a discussion of errors that may be expected from the 2-D simulations is provided.
Turbulent flow over a surface-mounted 2-D block: thermal stability effects
NASA Astrophysics Data System (ADS)
Zhang, Wei; Markfort, Corey; Porté-Agel, Fernando
2013-04-01
Momentum and scalar transport in turbulent boundary-layer flows over complex topography has been of great interest in the atmospheric sciences and wind engineering communities. The physical geometry of the topography, surface characteristics (e.g., roughness and temperature) and atmospheric thermal stability play important roles in momentum and scalar flux distribution. Numerous studies of flow over simplified topography, 2-D or 3-D blocks and sinusoidal hills have been conducted under neutral boundary-layer conditions. However, thermal stability effects are seldom taken into account due to the challenge of performing such laboratory simulations, for instance, wind-tunnel experiments. A limited number of experimental data sets are currently available, which severely hinders understanding of the underlying physics. Such data sets are also in high demand for development of new parameterization of surface fluxes and validation in numerical models such as Large-Eddy Simulation (LES). We present an experimental investigation of neutral and thermally-stratified boundary-layer flows over a surface-mounted 2-D block at the Saint Anthony Falls Laboratory boundary-layer wind tunnel. The 2-D block, with a width to height ratio of 2:1, was fully immersed in the surface layer of the turbulent boundary layer. Thermal stratification conditions were achieved by independently controlling the temperature of both the air flow and the test section floor and block surfaces. Measurements were obtained, using high-resolution PIV, x-wire/cold-wire anemometry and surface heat flux sensors, to quantify the thermal stability effects on the turbulent flow properties, especially the separation/recirculation zone, coherent vortex structures, the subsequent boundary layer recovery and spatial distribution of surface fluxes. This work aims to enhance our understanding of the thermal stability effects on the turbulent boundary-layer flows over complex topography, and provide a reliable database for validating and improving LES modeling.
Modeling and Control of 2-D Grasping of an Object with Arbitrary Shape under Rolling Contact
NASA Astrophysics Data System (ADS)
Arimoto, Suguru; Yoshida, Morio; Sekimoto, Masahiro; Tahara, Kenji
Modeling, control, and stabilization of dynamics of two-dimensional object grasping by using a pair of multi-joint robot fingers are investigated under rolling contact constraints and an arbitrary geometry of the object and fingertips. First, a fundamental testbed problem of modeling and control of rolling motion between 2-D rigid bodies with an arbitrary shape is treated under the assumption that the two contour curves coincide at the contact point and share the same tangent. The rolling constraint induces the Euler equation of motion that is parameterized by a common arclength parameter and constrained onto the kernel space orthogonally complemented to the image space spanned from the constraint gradient. By extending the analysis to the problem of stable grasp of a 2-D object with an arbitrary shape by a pair of robot fingers, the Euler-Lagrange equation of motion of the overall fingers/object system parametrized by arclength parameters is derived, together with a couple of first-order differential equations that express evolutions of contact points in terms of the second fundamental form. It is shown that 2-D rolling constraints are integrable in the sense of Frobonius even if their Pfaffian forms are characterized by arclength parameters. A control signal called “blind grasping” is introduced and shown to be effective in stabilization of grasping without using the details of the object shape and parameters or external sensing. An extension of the Dirichlet-Lagrange stability theorem to a class of systems with DOF-redundancy under constraints is suggested by using a Morse-Bott-Lyapunov function.
MATH 348 --TOPICS IN GEOMETRY FURTHER READING Euclidean Geometry
Do, Norman
MATH 348 -- TOPICS IN GEOMETRY FURTHER READING Euclidean Geometry The Elements by Euclid://faculty.evansville.edu/ck6/encyclopedia/ETC.html The Geometer's Sketchpad This is a program for drawing Euclidean geometry for drawing Euclidean geometry diagrams which I quite like. Unlike The Geometer's Sketchpad, the full program
Students Discovering Spherical Geometry Using Dynamic Geometry Software
ERIC Educational Resources Information Center
Guven, Bulent; Karatas, Ilhan
2009-01-01
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…
Investigations of flowfields found in typical combustor geometries
NASA Technical Reports Server (NTRS)
Lilley, D. G.
1982-01-01
Experimental and theoretical research undertaken on 2-D axisymmetric geometries under low speed, nonreacting, turbulent, swirling flow conditions is reported. The flow enters the test section and proceeds into a larger chamber (the expansion ratio D/d = 2) via a sudden or gradual expansion (sidewall angle alpha = 90 and 45 degrees). Inlet swirl vanes are adjustable to a variety of vane angles with values of phi = 0, 38, 45, 60 and 70 degrees being emphasized.
Radiative heat transfer in 2D Dirac materials
Pablo Rodriguez-Lopez; Wang-Kong Tse; Diego A. R. Dalvit
2015-02-02
We compute the radiative heat transfer between two sheets of 2D Dirac materials, including topological Chern insulators and graphene, within the framework of the local approximation for the optical response of these materials. In this approximation, which neglects spatial dispersion, we derive both numerically and analytically the short-distance asymptotic of the near-field heat transfer in these systems, and show that it scales as the inverse of the distance between the two sheets. Finally, we discuss the limitations to the validity of this scaling law imposed by spatial dispersion in 2D Dirac materials.
CH2D+, the Search for the Holy Grail
NASA Astrophysics Data System (ADS)
Roueff, Evelyne; Gerin, Maryvonne; Lis, Dariusz C.; Wootten, Alwyn; Marcelino, Nuria; Cernicharo, Jose; Tercero, Belen
2013-10-01
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.
CH2D(+), the search for the holy grail.
Roueff, Evelyne; Gerin, Maryvonne; Lis, Dariusz C; Wootten, Alwyn; Marcelino, Nuria; Cernicharo, Jose; Tercero, Belen
2013-10-01
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. PMID:23627602
2-D wavelet packet spectrum for texture analysis.
Atto, Abdourrahmane M; Berthoumieu, Yannick; Bolon, Philippe
2013-06-01
This brief derives a 2-D spectrum estimator from some recent results on the statistical properties of wavelet packet coefficients of random processes. It provides an analysis of the bias of this estimator with respect to the wavelet order. This brief also discusses the performance of this wavelet-based estimator, in comparison with the conventional 2-D Fourier-based spectrum estimator on texture analysis and content-based image retrieval. It highlights the effectiveness of the wavelet-based spectrum estimation. PMID:23412622
Design of the LRP airfoil series using 2D CFD
NASA Astrophysics Data System (ADS)
Zahle, Frederik; Bak, Christian; Sørensen, Niels N.; Vronsky, Tomas; Gaudern, Nicholas
2014-06-01
This paper describes the design and wind tunnel testing of a high-Reynolds number, high lift airfoil series designed for wind turbines. The airfoils were designed using direct gradient- based numerical multi-point optimization based on a Bezier parameterization of the shape, coupled to the 2D Navier-Stokes flow solver EllipSys2D. The resulting airfoils, the LRP2-30 and LRP2-36, achieve both higher operational lift coefficients and higher lift to drag ratios compared to the equivalent FFA-W3 airfoils.
Evaluation of 2D ceramic matrix composites in aeroconvective environments
NASA Technical Reports Server (NTRS)
Riccitiello, Salvatore R.; Love, Wendell L.; Balter-Peterson, Aliza
1992-01-01
An evaluation is conducted of a novel ceramic-matrix composite (CMC) material system for use in the aeroconvective-heating environments encountered by the nose caps and wing leading edges of such aerospace vehicles as the Space Shuttle, during orbit-insertion and reentry from LEO. These CMCs are composed of an SiC matrix that is reinforced with Nicalon, Nextel, or carbon refractory fibers in a 2D architecture. The test program conducted for the 2D CMCs gave attention to their subsurface oxidation.
2D Log-Gabor Wavelet Based Action Recognition
NASA Astrophysics Data System (ADS)
Li, Ning; Xu, De
The frequency response of log-Gabor function matches well the frequency response of primate visual neurons. In this letter, motion-salient regions are extracted based on the 2D log-Gabor wavelet transform of the spatio-temporal form of actions. A supervised classification technique is then used to classify the actions. The proposed method is robust to the irregular segmentation of actors. Moreover, the 2D log-Gabor wavelet permits more compact representation of actions than the recent neurobiological models using Gabor wavelet.
Magnetic structures of 2D and 3D nanoparticles
NASA Astrophysics Data System (ADS)
Levy, J.-C. S.
2015-01-01
The minimization of exchange interactions and dipolar interactions in 2D and 3D nanoparticles is obtained from a powerful variational approach of the local spin Hamiltonian and leads to a different set of equations which correspond to different levels of screening of the long range dipolar interactions. These equations are shown to introduce topological defects which are analyzed on the basis of elementary spin clusters. Four basic topological defects are deduced for 2D nanoparticles, as observed in magnetic samples and simulations and 10 basic topological defects are deduced for 3D nanoparticles. These singularities induce complex variations of magnetization around them and non-linear properties.
Modeling 2D Gyromagnetic Photonic Crystals by Modified FDTD Method
NASA Astrophysics Data System (ADS)
Li, Qing-Bo; Wu, Rui-Xin; Yang, Yan; Sun, Hui-Ling
2013-07-01
The band structures of two-dimensional (2D) gyromagnetic photonic crystals (PCs) are analyzed by a modified finite difference time domain (FDTD) method. A special implementation is used to tackle the magnetic constitution equation. This method avoids the discretizing complexity in the time domain caused by nonlinear frequency dependence of anisotropy permeability tensor, and therefore keeps the fully explicit nature of the original FDTD method. Our implementation is proved by the band structure calculations using other methods and the transmission measurements of 2D gyromagnetic PC involving circular ferrite rods and square rods.
NASA Astrophysics Data System (ADS)
Hosomichi, Kazuo; Lee, Sungjay
2015-01-01
We study the system of M2-branes suspended between parallel M5-branes using ABJM model with a natural half-BPS boundary condition. For small separation between M5-branes, the worldvolume theory is shown to reduce to a 2D super Yang-Mills theory with some similarity to q-deformed Yang-Mills theory. The gauge coupling is related to the position of the branes in an interesting manner. The theory is considerably different from the 2D theory proposed for multiple "M-strings". We make a detailed comparison of elliptic genus of the two descriptions and find only a partial agreement.
2dF grows up: Echidna for the AAT
NASA Astrophysics Data System (ADS)
McGrath, Andrew; Barden, Sam; Miziarski, Stan; Rambold, William; Smith, Greg
2008-07-01
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 capability of a redshift 1 survey of a large fraction of the southern sky, collecting five to ten thousand spectra per night for a million-galaxy survey.
Nomenclature for human CYP2D6 alleles.
Daly, A K; Brockmöller, J; Broly, F; Eichelbaum, M; Evans, W E; Gonzalez, F J; Huang, J D; Idle, J R; Ingelman-Sundberg, M; Ishizaki, T; Jacqz-Aigrain, E; Meyer, U A; Nebert, D W; Steen, V M; Wolf, C R; Zanger, U M
1996-06-01
To standardize CYP2D6 allele nomenclature, and to conform with international human gene nomenclature guidelines, an alternative to the current arbitrary system is described. Based on recommendations for human genome nomenclature, we propose that alleles be designated by CYP2D6 followed by an asterisk and a combination of roman letters and arabic numerals distinct for each allele with the number specifying the key mutation and, where appropriate, a letter specifying additional mutations. Criteria for classification as a separate allele and protein nomenclature are also presented. PMID:8807658
Noninvasive deep Raman detection with 2D correlation analysis
NASA Astrophysics Data System (ADS)
Kim, Hyung Min; Park, Hyo Sun; Cho, Youngho; Jin, Seung Min; Lee, Kang Taek; Jung, Young Mee; Suh, Yung Doug
2014-07-01
The detection of poisonous chemicals enclosed in daily necessaries is prerequisite essential for homeland security with the increasing threat of terrorism. For the detection of toxic chemicals, we combined a sensitive deep Raman spectroscopic method with 2D correlation analysis. We obtained the Raman spectra from concealed chemicals employing spatially offset Raman spectroscopy in which incident line-shaped light experiences multiple scatterings before being delivered to inner component and yielding deep Raman signal. Furthermore, we restored the pure Raman spectrum of each component using 2D correlation spectroscopic analysis with chemical inspection. Using this method, we could elucidate subsurface component under thick powder and packed contents in a bottle.
Submillimeter laboratory identification of CH+ and CH2D+
NASA Astrophysics Data System (ADS)
Amano, T.
2015-01-01
Laboratory identification of two basic and important interstellar molecular ions is presented. The J = 1 - 0 rotational transition of 12CH+ together with those of 13CH+ and 12CD+ was observed in the laboratory. The newly obtained frequencies were found to be different from those reported previously. Various experimental evidences firmly support the new measurements. In addition, the Zeeman effect and the spin-rotation hyperfine interaction enforce the laboratory identification with no ambiguity. Rotational lines of CH2D+ were observed in the submillimeter-wave region. This laboratory observation is consistent with a recent tentative identification of CH2D+ toward Ori IRc2.
NASA Astrophysics Data System (ADS)
Chen, Shang-Shang; Li, Ben-Wen
2014-12-01
A collocation spectral domain decomposition method (CSDDM) based on the influence matrix technique is developed to solve radiative transfer problems within a participating medium of 2D partitioned domains. In this numerical approach, the spatial domains of interest are decomposed into rectangular sub-domains. The radiative transfer equation (RTE) in each sub-domain is angularly discretized by the discrete ordinates method (DOM) with the SRAPN quadrature scheme and then is solved by the CSDDM directly. Three test geometries that include square enclosure and two enclosures with one baffle and one centered obstruction are used to validate the accuracy of the developed method and their numerical results are compared to the data obtained by other researchers. These comparisons indicate that the CSDDM has a good accuracy for all solutions. Therefore this method can be considered as a useful approach for the solution of radiative heat transfer problems in 2D partitioned domains.
Computation of neutron fluxes in clusters of fuel pins arranged in hexagonal assemblies (2D and 3D)
Prabha, H.; Marleau, G. [Institut de Genie Nucleaire, Ecole Polytechnique de Montreal, Stn. CV, P.O. Box 6079, Montreal, QC H3C 3A7 (Canada)
2012-07-01
For computations of fluxes, we have used Carvik's method of collision probabilities. This method requires tracking algorithms. An algorithm to compute tracks (in 2D and 3D) has been developed for seven hexagonal geometries with cluster of fuel pins. This has been implemented in the NXT module of the code DRAGON. The flux distribution in cluster of pins has been computed by using this code. For testing the results, they are compared when possible with the EXCELT module of the code DRAGON. Tracks are plotted in the NXT module by using MATLAB, these plots are also presented here. Results are presented with increasing number of lines to show the convergence of these results. We have numerically computed volumes, surface areas and the percentage errors in these computations. These results show that 2D results converge faster than 3D results. The accuracy on the computation of fluxes up to second decimal is achieved with fewer lines. (authors)
Integrable Background Geometries
NASA Astrophysics Data System (ADS)
Calderbank, David M. J.
2014-03-01
This work has its origins in an attempt to describe systematically the integrable geometries and gauge theories in dimensions one to four related to twistor theory. In each such dimension, there is a nondegenerate integrable geometric structure, governed by a nonlinear integrable differential equation, and each solution of this equation determines a background geometry on which, for any Lie group G, an integrable gauge theory is defined. In four dimensions, the geometry is selfdual conformal geometry and the gauge theory is selfdual Yang-Mills theory, while the lower-dimensional structures are nondegenerate (i.e., non-null) reductions of this. Any solution of the gauge theory on a k-dimensional geometry, such that the gauge group H acts transitively on an ?-manifold, determines a (k+?)-dimensional geometry (k+??4) fibering over the k-dimensional geometry with H as a structure group. In the case of an ?-dimensional group H acting on itself by the regular representation, all (k+?)-dimensional geometries with symmetry group H are locally obtained in this way. This framework unifies and extends known results about dimensional reductions of selfdual conformal geometry and the selfdual Yang-Mills equation, and provides a rich supply of constructive methods. In one dimension, generalized Nahm equations provide a uniform description of four pole isomonodromic deformation problems, and may be related to the {SU}(?) Toda and dKP equations via a hodograph transformation. In two dimensions, the {Diff}(S^1) Hitchin equation is shown to be equivalent to the hyperCR Einstein-Weyl equation, while the {SDiff}(?^2) Hitchin equation leads to a Euclidean analogue of Plebanski's heavenly equations. In three and four dimensions, the constructions of this paper help to organize the huge range of examples of Einstein-Weyl and selfdual spaces in the literature, as well as providing some new ! ones. The nondegenerate reductions have a long ancestry. More ! recently , degenerate or null reductions have attracted increased interest. Two of these reductions and their gauge theories (arguably, the two most significant) are also described.
Split Special Lagrangian Geometry
Harvey, F Reese
2010-01-01
One purpose of this article is to draw attention to the seminal work of J. Mealy in 1989 on calibrations in semi-riemannian geometry where split SLAG geometry was first introduced. The natural setting is provided by doing geometry with the complex numbers C replaced by the double numbers D, where i with i^2 = -1 is replaced by tau with tau^2 = 1. A rather surprising amount of complex geometry carries over, almost untouched, and this has been the subject of many papers. We briefly review this material and, in particular, we discuss Hermitian D-manifolds with trivial canonical bundle, which provide the background space for the geometry of split SLAG submanifolds. A removable singularities result is proved for split SLAG subvarieties. It implies, in particular, that there exist no split SLAG cones, smooth outside the origin, other than planes. This is in sharp contrast to the complex case. Parallel to the complex case, space-like Lagrangian submanifolds are stationary if and only if they are theta-split SLAG for...
Rickard Jonsson; Hans Westman
2007-08-21
We show that by employing the standard projected curvature as a measure of spatial curvature, we can make a certain generalization of optical geometry (Abramowicz and Lasota 1997, Class. Quantum Grav. 14 (1997) A23). This generalization applies to any spacetime that admits a hypersurface orthogonal shearfree congruence of worldlines. This is a somewhat larger class of spacetimes than the conformally static spacetimes assumed in standard optical geometry. In the generalized optical geometry, which in the generic case is time dependent, photons move with unit speed along spatial geodesics and the sideways force experienced by a particle following a spatially straight line is independent of the velocity. Also gyroscopes moving along spatial geodesics do not precess (relative to the forward direction). Gyroscopes that follow a curved spatial trajectory precess according to a very simple law of three-rotation. We also present an inertial force formalism in coordinate representation for this generalization. Furthermore, we show that by employing a new sense of spatial curvature (Jonsson, Class. Quantum Grav. 23 (2006) 1) closely connected to Fermat's principle, we can make a more extensive generalization of optical geometry that applies to arbitrary spacetimes. In general this optical geometry will be time dependent, but still geodesic photons move with unit speed and follow lines that are spatially straight in the new sense. Also, the sideways experienced (comoving) force on a test particle following a line that is straight in the new sense will be independent of the velocity.
Gressier, F; Verstuyft, C; Hardy, P; Becquemont, L; Corruble, E
2015-01-01
The cytochrome P450 2D6 (CYP2D6) is involved in the metabolism of most antidepressants. Comedication with a potent CYP2D6 inhibitor can convert patients with extensive metabolizer (EM) or ultra-rapid metabolizer (UM) genotypes into poor metabolizer (PM) phenotypes. Since comedication is frequent in depressed patients treated with antidepressants, we investigated the effect of the CYP2D6 composite phenotype on antidepressant efficacy, taking into account both the CYP2D6 genotype and comedication with CYP2D6 inhibitors. 87 Caucasian in patients with a major depressive episode were prospectively treated with flexible doses of antidepressant monotherapy as well as comedications and genotyped for the major CYP2D6 alleles (CYP2D6*3 rs35742686, *4 rs3892097, *5 del, *6 rs5030655, and *2xN). They were classified for CYP2D6 composite phenotype and assessed for antidepressant response after 4 weeks. In terms of genotypes (g), 6 subjects were UMg, 6 PMg, and 75 EMg. Ten patients were coprescribed a CYP2D6 inhibitor, resulting in the following composite phenotypes (cp): 5 UMcp, 16 PMcp, and 66 EMcp. Whereas none of the CYP2D6 genotypes were significantly associated with antidepressant response, UMcp had a lower antidepressant response than PMcp or EMcp (respectively: 39.0 ± 17.9, 50.0 ± 26.0, and 61.6 ± 23.4, p = 0.02). Despite small sample size, this study suggests that a CYP2D6 composite phenotype, taking into account both genotype and comedications with CYP2D6 inhibitors, could predict CYP2D6 substrate antidepressants response. Thus, to optimize antidepressant response, CYP2D6 genotype could be performed and comedications with CYP2D6 inhibitors should be avoided, when prescribing CYP2D6 substrate antidepressants. PMID:25047911
An Introduction to Projective Geometry
NSDL National Science Digital Library
Birchfield, Stan
The contents of this paper include: The Projective Plane; Projective Space; Projective Geometry Applied to Computer Vision; Demonstration of Cross Ratio in P^1; and a bibliography. (Euclidean geometry is a subset of projective geometry, and there are two geometries between them: similarity and affine.) Also at http://vision.stanford.edu/~birch/projective/.
Three-Dimensional Geometry and
Landweber, Laura
Three-Dimensional Geometry and Topology William P. Thurston This book was the ori- gin of a grand spaces. To do this, he had to establish the strong connection of geometry to topology--the study- pression "Thurston-type geometry" has become a commonplace. Three-Dimensional Geometry and Topology had its
Geometry, noncommutative algebra and representations
Wirosoetisno, Djoko
Geometry, noncommutative algebra and representations Iain Gordon http://www.maths.ed.ac.uk/~igordon/ University of Edinburgh 16th December 2006 1 Iain Gordon Geometry, noncommutative algebra and representations #12;2 Iain Gordon Geometry, noncommutative algebra and representations #12;Outline 1 Geometry
Topics in Geometry Olga Kharlampovich
Kharlampovich, Olga
. Symmetry in the real world Â² Euclidean and non-Euclidean geometry 1. History 2. Plane Euclidean geometry, 3 mathematics, AMS, Mathematical world, Vol. 5, 1996 P.J. Ryan, Euclidean and non-Euclidean geometry. AÂ±ne transformations in the Euclidean plane, 4. Finite groups of isometries of E2 , 5. Geometry
Matrix Models and 2D Critical String Theory --2D Black Hole by c=1 Matrix Model--
Tamiaki Yoneya
1992-11-18
(Lecture at the workshop "Basic Problems in String Theory", Yukawa Institute for Theoretical Physics, Kyoto, October 19-21) In this talk, we first review the possibility of matrix models toward a nonperturbative (critical) string theory. We then discuss whether the $c=1$ matrix model can describe the black hole solution of 2D critical string theory. We show that there exists a class of integral transformations which send the Virasoro condition for the tachyon field around the 2D black hole to that around the linear dilaton vacuum. In particular, we construct an explicit integral formula wihich describes a continuous deformation of the linear dilaton vacuum to the black hole background.
Discrepant Results in a 2-D Marble Collision
ERIC Educational Resources Information Center
Kalajian, Peter
2013-01-01
Video analysis of 2-D collisions is an excellent way to investigate conservation of linear momentum. The often-desired experimental design goal is to minimize the momentum loss in order to demonstrate the conservation law. An air table with colliding pucks is an ideal medium for this experiment, but such equipment is beyond the budget of many…
2D signature for detection and identification of drugs
NASA Astrophysics Data System (ADS)
Trofimov, Vyacheslav A.; Varentsova, Svetlana A.; Shen, Jingling; Zhang, Cunlin; Zhou, Qingli; Shi, Yulei
2011-06-01
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.
A Meshless Method for Variational Nonrigid 2-D Shape Registration
Ribeiro, Eraldo
A Meshless Method for Variational Nonrigid 2-D Shape Registration Wei Liu and Eraldo Ribeiro to a variational functional. Secondly, we in- troduce a meshless deformation model that can adapt computation and a meshless deformation model. Shape registration is an ill-posed problem as there can be many ambiguous
Pervasive 2D Barcodes for Camera Phone Applications
Hiroko Kato; Keng T. Tan
2007-01-01
In a previous study, we evaluated six 2D barcodes using eight criteria for standardization potential: omnidirectional symbol reading, support for low-resolution cameras, reading robustness under different lighting conditions, barcode reading distance, error correction capability, security, support for multiple character sets, and data capacity. We also considered the fidelity of the camera phone's captured image as a metric for gauging reading
INVERSE DESIGN OF 2-D AIRFOIL VIA VIBRATIONAL GENETIC ALGORITHM
Y. Volkan PEHLIVANOGLU; Abdurrahman HACIOGLU
Within this study, it is aimed to provide an efficient algorithm for inverse design of 2-D airfoil in different flow conditions. For this purpose, as a stochastic search method, current vibrational genetic algorithm (VGA) is improved and used to accelerate the algorithm for inverse design. From the results obtained, it is concluded that VGA decreased the required time for optimal
ADVANCES IN 2-D CORRELATION IN NIR SPECTROSCOPY
Technology Transfer Automated Retrieval System (TEKTRAN)
Two-dimensional (2-D) vibrational correlation spectroscopy has now advanced to the stage of realizing many of its touted advantages. Those advantages primarily are: elucidation of chemical interactions of functional groups, simplification of complex spectra, enhancement of spectral resolution by sp...
Motion indicators in the 2D standard map
NASA Astrophysics Data System (ADS)
Süli, Á.
2006-09-01
In this article four motion (chaos) indicators were analyzed and compared using the framework of the 2D standard map. These indicators, namely the LCE, FLI, RLI and SALI may provide a global picture of the phase space. Until now a detailed comparison of these methods have not been performed. To supersede this imperfection is the aim of the present paper.
Graphene band structure and its 2D Raman mode
NASA Astrophysics Data System (ADS)
Narula, Rohit; Reich, Stephanie
2014-08-01
High-precision simulations are used to generate the 2D Raman mode of graphene under a range of screening conditions and laser energies EL. We reproduce the decreasing trend of the 2D mode FWHM vs EL and the nearly linearly increasing dispersion ??2D/?EL seen experimentally in freestanding (unscreened) graphene, and propose relations between these experimentally accessible quantities and the local, two-dimensional gradients |? | of the electronic and TO phonon bands. In light of state-of-the-art electronic structure calculations that acutely treat the long-range e-e interactions of isolated graphene and its experimentally observed 2D Raman mode, our calculations determine a 40% greater slope of the TO phonons about K than given by explicit phonon measurements performed in graphite or GW phonon calculations in graphene. We also deduce the variation of the broadening energy ? [EL] for freestanding graphene and find a nominal value ? ˜140 meV, showing a gradually increasing trend for the range of frequencies available experimentally.
2D Parameterized Inversions of Marine CSEM Data
B. Wheelock; S. Constable
2008-01-01
As an alternative to the computational and algorithmic complexity of regularized inversion, we investigate the use of lightly parameterized 2D inversions of marine controlled source electromagnetic (CSEM) data. Since a priori information from seismics is often available, this overdetermined scheme offers a way to make use of additional information in an inversion that will run faster than a regularized, underdetermined
Inviscid Limit for 2D Stochastic Navier-Stokes equations
Fernanda Cipriano; Iván Torrecilla
2014-05-02
We consider stochastic Navier-Stokes equations in a 2D-bounded domain with the Navier with friction boundary condition. We establish the existence and the uniqueness of the solutions and study the vanishing viscosity limit. More precisely, we prove that solutions of stochastic Navier-Stokes equations converge, as the viscosity goes to zero, to solutions of the corresponding stochastic Euler equations.
ENVIRONMENTAL EFFECTS OF DREDGING AND DISPOSAL (E2-D2)
US Army Corps of Engineers public web site for the "Environmental Effects of Dredging and Disposal" ("E2-D2") searchable database of published reports and studies about environmental impacts associated with dredging and disposal operations. Many of the reports and studies are ava...
Motion-Synthesis Techniques for 2D Articulated Figures
Alex Fukunaga; Lloyd Hsu
In this paper we extend previous work on automatic motion syn- thesis for physically realistic 2D articulated figures in three ways. First, we describe an improved motion-synthesis algorithm that runs substantially faster than previously reported algorithms. Sec- ond, we present two new techniques for influencing the style of the motions generated by the algorithm. These techniques can be used by
Protein Folding in 3-d and 2-d
NSDL National Science Digital Library
Brian White (University of Massachusetts; )
2006-06-18
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.
RICE UNIVERSITY Millimeter Wave Transmission Spectroscopy of 2D
Natelson, Douglas
RICE UNIVERSITY Millimeter Wave Transmission Spectroscopy of 2D Electron and Hole Systems was accepted to Rice's Physics and Astronomy Department two weeks before classes started and arrived one week myself at Rice University with friends and mentors who have been invaluable resources. They have made
Responsive ionic liquidpolymer 2D photonic crystal gas sensors
Asher, Sanford A.
, ethylguanidine perchlorate (EGP) as the mobile phase. Because of the negligible ionic liquid vapor pressure(hydroxyethyl methacrylate) (pHEMA)-based polymer networks dispersed in EGP. The wavelength of the bright 2D photonic crystal of the EGPÂpHEMA system to water vapor or gaseous ammonia changes the 2DPC particle spacing, enabling
Limit current density in 2D metallic granular packings
S. Dorbolo; M. Ausloosand; N. Vandewalle
2003-01-01
The electrical properties of a 2D packed metallic pentagons have been studied. The electrical characterization of such metallic pentagon heaps, like i- V measurements, has been achieved. Two distinct regimes have been shown. They are separated by a transition line along which the system exhibits a memory effect behavior due to the irreversible improvement of electrical contacts between pentagons (hot
Point-Force Response in 2D Granular Materials
Junfei Geng; R. P. Behringer; G. Redellet; Eric Clément
2002-01-01
Competing theories based on substantially different mechanisms predict correspondingly different results for force propagation in static granular materials. We explore this issue through experiments using 2D arrays of photoelastic particles (disks and pentagons) for which we can determine the force on a particle. A local point force is applied to one particle and the change in the force chain network
Green's Function Measurement in a 2D Granular Material
Junfei Geng; Daniel W. Howell; Emily Longhi; R. P. Behringer; G. Reydellet; L. Vanel; E. Clement; S. Luding
2001-01-01
We experimentally determine ensemble-averaged responses of granular packings to point forces. We use 2D granular arrays consisting of photoelastic particles: either disks or pentagons, thus spanning the range from ordered to disordered packings. A key finding is that spatial ordering of the particles is a key factor in the force response. Ordered packings have a propagative component that does not
Silver Staining of 2D Electrophoresis Gels Thierry Rabilloud
Paris-Sud XI, UniversitÃ© de
Silver Staining of 2D Electrophoresis Gels Thierry Rabilloud CEA-DSV-iRTSV/LCBM and UMR CNRS separation on polyacrylamide gels. It combines excellent sensitivity (in the low nanogram range) with the use spectrometry, quantification, polyacrylamide gels, protein visualisation, silver staining #12;1. Introduction
INDEPENDENT COMPONENT ANALYSIS OF SIMULATED 2D ELECTROPHORESIS GELS
Adali, Tulay
INDEPENDENT COMPONENT ANALYSIS OF SIMULATED 2D ELECTROPHORESIS GELS Nicolle Correat, Haleh Safavit differentially expressed pro- teins in simulated two-dimensional electrophoresis (2DE) gels us- ing spatial in the spatial domain. 1. INTRODUCTION Two-dimensional electrophoresis (2DE) gel has been widely used to separate
2-D Imaging of Electron Temperature in Tokamak Plasmas
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
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.
ELLIPT2D: A Flexible Finite Element Code Written Python
Pletzer, A.; Mollis, J.C.
2001-03-22
The use of the Python scripting language for scientific applications and in particular to solve partial differential equations is explored. It is shown that Python's rich data structure and object-oriented features can be exploited to write programs that are not only significantly more concise than their counter parts written in Fortran, C or C++, but are also numerically efficient. To illustrate this, a two-dimensional finite element code (ELLIPT2D) has been written. ELLIPT2D provides a flexible and easy-to-use framework for solving a large class of second-order elliptic problems. The program allows for structured or unstructured meshes. All functions defining the elliptic operator are user supplied and so are the boundary conditions, which can be of Dirichlet, Neumann or Robbins type. ELLIPT2D makes extensive use of dictionaries (hash tables) as a way to represent sparse matrices.Other key features of the Python language that have been widely used include: operator over loading, error handling, array slicing, and the Tkinter module for building graphical use interfaces. As an example of the utility of ELLIPT2D, a nonlinear solution of the Grad-Shafranov equation is computed using a Newton iterative scheme. A second application focuses on a solution of the toroidal Laplace equation coupled to a magnetohydrodynamic stability code, a problem arising in the context of magnetic fusion research.
2D Static Light Scattering for Dairy Based Applications
2D Static Light Scattering for Dairy Based Applications Jacob Lercke Skytte Kongens Lyngby 2014 Ph an exploratory study in relation to dairy based applications, with a major emphasis on the microstructure for Strategic Research (contract no. 09-067039) within the Programme Commission on Health, Food and welfare
"Stem Cell Migration on 2D Biomaterials Platforms" Tyler Vlass
Mountziaris, T. J.
"Stem Cell Migration on 2D Biomaterials Platforms" Tyler Vlass Faculty Mentor: Dr. Shelly Peyton, Chemical Engineering The research project I will be working on this summer deals with stem cell motility. I will be building off of research done by the Peyton Lab. When testing stem cell movement on 3D scaffolds
Volume Calculation of Venous Thrombosis Using 2D Ultrasound Images.
Dhibi, M; Puentes, J; Bressollette, L; Guias, B; Solaiman, B
2005-01-01
Venous thrombosis screening exams use 2D ultrasound images, from which medical experts obtain a rough idea of the thrombosis aspect and infer an approximate volume. Such estimation is essential to follow up the thrombosis evolution. This paper proposes a method to calculate venous thrombosis volume from non-parallel 2D ultrasound images, taking advantage of a priori knowledge about the thrombosis shape. An interactive ellipse fitting contour segmentation extracts the 2D thrombosis contours. Then, a Delaunay triangulation is applied to the set of 2D segmented contours positioned in 3D, and the area that each contour defines, to obtain a global thrombosis 3D surface reconstruction, with a dense triangulation inside the contours. Volume is calculated from the obtained surface and contours triangulation, using a maximum unit normal component approach. Preliminary results obtained on 3 plastic phantoms and 3 in vitro venous thromboses, as well as one in vivo case are presented and discussed. An error rate of volume estimation inferior to 4,5% for the plastic phantoms, and 3,5% for the in vitro venous thromboses was obtained. PMID:17281109
Face Recognition Using 2D and 3D Facial Data
Kyong I. Chang; Kevin W. Bowyer; Patrick J. Flynn
2003-01-01
Results are presented for the largest experimental study to date that investigates the comparison and combination of 2D and 3D face recognition. To our knowledge, this is also the only such study to incorporate signicant time lapse be- tween gallery and probe image acquisition, and to look at the effect of depth resolution. Recognition results are ob- tained in (1)
The 2-D Leap-Frog: Integrability, Noise, and Digitization
Kozera, Ryszard
The 2-D Leap-Frog: Integrability, Noise, and Digitization Lyle Noakes a and Ryszard Kozera b and Software Engineering b , 35 Stirling Highway, Crawley WA 6009, Australia Summary. The 1-D Leap-Frog paper ? we adapt Leap- Frog to solve an optimization problem in computer vision. The vision problem
2D and 3D Elasticity Imaging Using Freehand Ultrasound
Drummond, Tom
2D and 3D Elasticity Imaging Using Freehand Ultrasound Joel Edward Lindop Pembroke College March to mechanical properties (e.g., stiffness) to which conventional forms of ultrasound, X-ray and magnetic that occur between the acquisition of multiple ultrasound images. Likely applications include improved
NASA Astrophysics Data System (ADS)
Ochiai, T.; Nacher, J. C.
2011-09-01
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.
Strings on Bubbling Geometries
Hai Lin; Alexander Morisse; Jonathan P. Shock
2011-07-27
We study gauge theory operators which take the form of a product of a trace with a Schur polynomial, and their string theory duals. These states represent strings excited on bubbling AdS geometries which are dual to the Schur polynomials. These geometries generically take the form of multiple annuli in the phase space plane. We study the coherent state wavefunction of the lattice, which labels the trace part of the operator, for a general Young tableau and their dual description on the droplet plane with a general concentric ring pattern. In addition we identify a density matrix over the coherent states on all the geometries within a fixed constraint. This density matrix may be used to calculate the entropy of a given ensemble of operators. We finally recover the BMN string spectrum along the geodesic near any circle from the ansatz of the coherent state wavefunction.
Holographic Entanglement Entropy from 2d CFT: Heavy States and Local Quenches
Curtis T. Asplund; Alice Bernamonti; Federico Galli; Thomas Hartman
2014-10-22
We consider the entanglement entropy in 2d conformal field theory in a class of excited states produced by the insertion of a heavy local operator. These include both high-energy eigenstates of the Hamiltonian and time-dependent local quenches. We compute the universal contribution from the stress tensor to the single interval Renyi entropies and entanglement entropy, and conjecture that this dominates the answer in theories with a large central charge and a sparse spectrum of low-dimension operators. The resulting entanglement entropies agree precisely with holographic calculations in three-dimensional gravity. High-energy eigenstates are dual to microstates of the BTZ black hole, so the corresponding holographic calculation is a geodesic length in the black hole geometry; agreement between these two answers demonstrates that entanglement entropy thermalizes in individual microstates of holographic CFTs. For local quenches, the dual geometry is a highly boosted black hole or conical defect. On the CFT side, the rise in entanglement entropy after a quench is directly related to the monodromy of a Virasoro conformal block.
Fully coupled nonlinear thermomechanical analysis including general contact in PALM2D
Engelmann, B.E.; Whirley, R.G.
1993-10-07
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.
Holographic entanglement entropy from 2d CFT: heavy states and local quenches
NASA Astrophysics Data System (ADS)
Asplund, Curtis T.; Bernamonti, Alice; Galli, Federico; Hartman, Thomas
2015-02-01
We consider the entanglement entropy in 2d conformal field theory in a class of excited states produced by the insertion of a heavy local operator. These include both high-energy eigenstates of the Hamiltonian and time-dependent local quenches. We compute the universal contribution from the stress tensor to the single interval Renyi entropies and entanglement entropy, and conjecture that this dominates the answer in theories with a large central charge and a sparse spectrum of low-dimension operators. The resulting entanglement entropies agree precisely with holographic calculations in three-dimensional gravity. High-energy eigenstates are dual to microstates of the BTZ black hole, so the corresponding holographic calculation is a geodesic length in the black hole geometry; agreement between these two answers demonstrates that these individual microstates of holographic CFTs effectively thermalize at the level of the single-interval entanglement entropy. For local quenches, the dual geometry is a highly boosted black hole or conical defect. On the CFT side, the rise in entanglement entropy after a quench is directly related to the monodromy of a Virasoro conformal block.
Cytochrome P450-2D6 Screening Among Elderly Using Antidepressants (CYSCE)
2015-01-06
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
NSDL National Science Digital Library
Eppstein, David
This metasite "collects various areas in which ideas from discrete and computational geometry (meaning mainly low-dimensional Euclidean geometry) meet some real world applications," according to the site's provider, Dr. David Eppstein of the University of California at Irvine. Categories available include Geometric References and Techniques, Design and Manufacturing, Graphics and Visualization, Information Systems, Medicine and Biology, Physical Sciences, Robotics, Other Applications, and Recent Additions. The types of links included are data sets, patents, journal articles, and research pages (note: a few of the links don't work, but overall the site is useful).
Noncommutative Geometry and Arithmetic
Matilde Marcolli
2010-03-18
This is an overview of recent results aimed at developing a geometry of noncommutative tori with real multiplication, with the purpose of providing a parallel, for real quadratic fields, of the classical theory of elliptic curves with complex multiplication for imaginary quadratic fields. This talk concentrates on two main aspects: the relation of Stark numbers to the geometry of noncommutative tori with real multiplication, and the shadows of modular forms on the noncommutative boundary of modular curves, that is, the moduli space of noncommutative tori. To appear in Proc. ICM 2010.
NASA Astrophysics Data System (ADS)
Kraloua, B.; Hennad, A.
2008-09-01
The aim of this paper is to determine electric and physical properties by 2D modelling of glow discharge low pressure in continuous regime maintained by term constant source. This electric discharge is confined in reactor plan-parallel geometry. This reactor is filled by Argon monatomic gas. Our continuum model the order two is composed the first three moments the Boltzmann's equations coupled with Poisson's equation by self consistent method. These transport equations are discretized by the finite volumes method. The equations system is resolved by a new technique, it is about the N-BEE explicit scheme using the time splitting method.
Kraloua, B.; Hennad, A. [Universite des Sciences et de la Technologie d'Oran Mohamed Boudiaf Faculte de Genie Electrique, Departement d'Electrotechnique Laboratoire de Modelisation de Systemes Electrotechniques et Systemes Experts (LMSE) BP. 1505 EL M'Naouar, 31000 Oran (Algeria)
2008-09-23
The aim of this paper is to determine electric and physical properties by 2D modelling of glow discharge low pressure in continuous regime maintained by term constant source. This electric discharge is confined in reactor plan-parallel geometry. This reactor is filled by Argon monatomic gas. Our continuum model the order two is composed the first three moments the Boltzmann's equations coupled with Poisson's equation by self consistent method. These transport equations are discretized by the finite volumes method. The equations system is resolved by a new technique, it is about the N-BEE explicit scheme using the time splitting method.
The Anglo-Australian Observatory's 2dF Facility
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
2002-02-08
The 2dF (Two-degree Field) facility at the prime focus of the Anglo-Australian Telescope provides multiple object spectroscopy over a 2 degree 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 440nm and 110nm respectively. The 2dF facility began routine observations in 1997. 2dF was designed primarily for galaxy redshift surveys and has a number of innovative features. The large corrector lens incorporates an atmospheric dispersion compensator, essential for wide wavelength coverage with small diameter fibres. The instrument has two full sets of fibres on separate field plates, so that re-configuring can be done in parallel with observing. The robot positioner places one fibre every 6 seconds, to a precision of 0.3 arcsec (20micron) over the full field. All components of 2dF, including the spectrographs, are mounted on a 5-m diameter telescope top-end ring for ease of handling and to keep the optical fibres short in order to maximise UV throughput . There is a pipeline data reduction system which allows each data set to be fully analysed while the next field is being observed. In this paper we provide the historical background to the 2dF facility, the design philosophy, a full technical description and a summary of the performance of the instrument. We also briefly review its scientific applications and possible future developments.
Euclidean geometry as algorithm for construction of generalized geometries
Yuri A. Rylov
2005-11-23
It is shown that the generalized geometries may be obtained as a deformation of the proper Euclidean geometry. Algorithm of construction of any proposition S of the proper Euclidean geometry E may be described in terms of the Euclidean world function sigma_E in the form S(sigma_E). Replacing the Euclidean world function sigma_E by the world function sigma of the geometry G, one obtains the corresponding proposition S(sigma) of the generalized geometry G. Such a construction of the generalized geometries (known as T-geometries) uses well known algorithms of the proper Euclidean geometry and nothing besides. This method of the geometry construction is very simple and effective. Using T-geometry as the space-time geometry, one can construct the deterministic space-time geometries with primordially stochastic motion of free particles and geometrized particle mass. Such a space-time geometry defined properly (with quantum constant as an attribute of geometry) allows one to explain quantum effects as a result of the statistical description of the stochastic particle motion (without a use of quantum principles).
Catadioptric Projective Geometry
Christopher Geyer; Konstantinos Daniilidis
2001-01-01
Catadioptric sensors are devices which utilize mirrors and lenses to form a projection onto the image plane of a camera. Central catadioptric sensors are the class of these devices having a single effective viewpoint. In this paper, we propose a unifying model for the projective geometry induced by these devices and we study its properties as well as its practical
Noncommutative Projective Geometry
J. T. Stafford
\\u000a The aim of the three lectures I gave at Constanta was to introduce the audience to the theory of “Noncommutative Pro- jective\\u000a Geometry.” The material for these talks was taken from the survey article (6) and so this abstract will give a very brief discussion of this material leaving the reader to see (6) for the details.
ERIC Educational Resources Information Center
Shilgalis, Thomas W.
1985-01-01
The results of investigations into finite geometries, prompted by questions raised in a course for secondary school mathematics teachers, are presented. The discussion of points, lines, and incidences led to consideration of graphs of second-degree equations in finite projective planes. (MNS)
Hsü, K J; Hsü, A J
1990-01-01
Music critics have compared Bach's music to the precision of mathematics. What "mathematics" and what "precision" are the questions for a curious scientist. The purpose of this short note is to suggest that the mathematics is, at least in part, Mandelbrot's fractal geometry and the precision is the deviation from a log-log linear plot. PMID:11607061
Spacetime and Euclidean geometry
NASA Astrophysics Data System (ADS)
Brill, Dieter; Jacobson, Ted
2006-04-01
Using only the principle of relativity and Euclidean geometry we show in this pedagogical article that the square of proper time or length in a two-dimensional spacetime diagram is proportional to the Euclidean area of the corresponding causal domain. We use this relation to derive the Minkowski line element by two geometric proofs of the spacetime Pythagoras theorem.
Spacetime and Euclidean Geometry
Dieter Brill; Ted Jacobson
2004-08-04
Using only the principle of relativity and Euclidean geometry we show in this pedagogical article that the square of proper time or length in a two-dimensional spacetime diagram is proportional to the Euclidean area of the corresponding causal domain. We use this relation to derive the Minkowski line element by two geometric proofs of the "spacetime Pythagoras theorem".
NSDL National Science Digital Library
Hardaker, Chris.
This Website, sprung from a gifted-and-talented program for K-12 students in Arizona, presents the interesting world of Native American geometry, a system based on the proportional relationship between the radius and circumference of a circle. The eye-pleasing site, divided into sections that include Foundations, Education, Designs, and Anthropology, would be appealing to curious Web surfers along with mathematics students. Geometric principles of proportions and angles are presented in the context of Native American designs, joining art and science and allowing students to learn in a creative, applied fashion. Some highlights of the site include illustrated examples of how corporate logos such as those of Mitsubishi or CBS Television are based on this geometry and a page on the architectural geometries of archaeologic sites such as Chaco Canyon, NM. A brief discussion of the history of circle-based ("string and two sticks") geometry throughout the world and a list of references for teachers are also important parts of this site.
Dragon Shapes: Geometry Challenge
NSDL National Science Digital Library
Lighthouse Learning Studios Ltd
2013-10-14
This iOS app requires users to apply their knowledge of geometry to solve Tangram puzzles. The app introduces the challenge through a brief episode and then provides challenges of increasing difficulty throughout level 1. There are fourteen free puzzles in all, with additional puzzles available through an in app purchase.
ERIC Educational Resources Information Center
Cooper, Brett D.; Barger, Rita
2009-01-01
The many connections between music and mathematics are well known. The length of a plucked string determines its tone, the time signature of a piece of music is a ratio, and note durations are measured in fractions. One connection commonly overlooked is that between music and geometry--specifically, geometric transformations, including…
Atiyah, Michael; Dijkgraaf, Robbert; Hitchin, Nigel
2010-01-01
We review the remarkably fruitful interactions between mathematics and quantum physics in the past decades, pointing out some general trends and highlighting several examples, such as the counting of curves in algebraic geometry, invariants of knots and four-dimensional topology. PMID:20123740
Creative Thinking with Geometry.
ERIC Educational Resources Information Center
Jean, Roger V.
1985-01-01
Argues that Euclidean geometry should assume the central role it once had in mathematics education, describing a teaching method that uses slides made with superimposed overhead projector transparencies. The method (constituting a game of clues and hints) assumes students understand deduction and the roles of postulates, theorems, and proofs. (JN)
Spacetime and Euclidean geometry
Dieter Brill; Ted Jacobson
2006-01-01
Using only the principle of relativity and Euclidean geometry we show in this pedagogical article that the square of proper time or length in a two-dimensional spacetime diagram is proportional to the Euclidean area of the corresponding causal domain. We use this relation to derive the Minkowski line element by two geometric proofs of the spacetime Pythagoras theorem.
Multifold Euclidean geometry codes
Shu Lin
1973-01-01
This paper presents a class of majority-logic decodable codes whose structure is based on the structural properties of Euclidean geometries (EG) and codes that are invariant under the affine group of permutations. This new class of codes contains the ordinary EG codes and some generalized EG codes as subclasses. One subclass of new codes is particularly interesting: they are the
Donald Black
2004-01-01
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
ERIC Educational Resources Information Center
Case, Christine L.
1991-01-01
Presented is an activity in which students make models of viruses, which allows them to visualize the shape of these microorganisms. Included are some background on viruses, the biology and geometry of viruses, directions for building viruses, a comparison of cells and viruses, and questions for students. (KR)
Perennnial Problems from Geometry
Tom Rike; Berkeley Math Circle
This geometry problem which is the major focus of the talk today dates back to at least 1815, when it appeared as question 1029 in The Gentleman's Diary. One of the solvers was W.G. Horner whose name is associated with Horner's Method of approximating zeros of polynomials. In R.A. Johnson's treatise of 1929 (11) ,a proof by Mackay from the
NSDL National Science Digital Library
Amy R. Taylor
2007-01-01
Advances in nanotechnology are due in part to the unique structure and properties of carbon nanotubes and buckyballs. These unusual structures are being studied for their potential use as vehicles for drug delivery, to strengthen materials, and as miniature circuits. Through an examination of the geometry of nanoscale materials, students explore the possibilities of nanoscale technologies.
Sliding vane geometry turbines
Sun, Harold Huimin; Zhang, Jizhong; Hu, Liangjun; Hanna, Dave R
2014-12-30
Various systems and methods are described for a variable geometry turbine. In one example, a turbine nozzle comprises a central axis and a nozzle vane. The nozzle vane includes a stationary vane and a sliding vane. The sliding vane is positioned to slide in a direction substantially tangent to an inner circumference of the turbine nozzle and in contact with the stationary vane.
Advanced geometries and regimes
Bulanov, S. S. [Univeristy of California, Berkeley, CA, 94720 (United States)] [Univeristy of California, Berkeley, CA, 94720 (United States); Bulanov, S. V. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan)] [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Turchetti, G. [Dipartimento di Fisica, Università di Bologna and INFN Sezione di Bologna, Via Irnerio, 46-I-40126 Bologna (Italy)] [Dipartimento di Fisica, Università di Bologna and INFN Sezione di Bologna, Via Irnerio, 46-I-40126 Bologna (Italy); Limpouch, J.; Klimo, O.; Psikal, J. [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague, Czech Republic and Czech Technical University in Prague, FNSPE, Brehova 7, 115 19 Prague (Czech Republic)] [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague, Czech Republic and Czech Technical University in Prague, FNSPE, Brehova 7, 115 19 Prague (Czech Republic); Antici, P. [Dipartimento di Energetica ed INFM, Università di Roma, La Sapienza, 00165 Roma (Italy)] [Dipartimento di Energetica ed INFM, Università di Roma, La Sapienza, 00165 Roma (Italy); Margarone, D.; Korn, G. [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague (Czech Republic)] [Institute of Physics of the ASCR, ELI-Beamlines/HiLASE project, Na Slovance 2, 18221 Prague (Czech Republic)
2013-07-26
We review and discuss different schemes of laser ion acceleration as well as advanced target geometries in connection with the development of the laser-driven proton source for hadron therapy of oncological diseases, which is a part of the ELIMED project.
E. Atzmon
In a one-dimensional lattice, the induced metric (from a noncommutative geometry calculation) breaks translation invariance. This leads to some inconsistencies among different spectator frames, in the observation of the hoppings of a test particle between lattice sites. To resolve the inconsistencies between the different spectator frames, we replace the test particle's bare mass by an effective locally dependent mass. This
Quantum Entanglement and Geometry
Andreas Gabriel
2010-03-19
The phenomenon of quantum entanglement is thoroughly investigated, focussing especially on geometrical aspects and on bipartite systems. After introducing the formalism and discussing general aspects, some of the most important separability criteria and entanglement measures are presented. Finally, the geometry of 2x2- and 3x3-dimensional state spaces is analysed and visualised.
ERIC Educational Resources Information Center
Martin, John
2010-01-01
The cycloid has been called the Helen of Geometry, not only because of its beautiful properties but also because of the quarrels it provoked between famous mathematicians of the 17th century. This article surveys the history of the cycloid and its importance in the development of the calculus.
NSDL National Science Digital Library
Terese Herrera
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.
2-D linear motion system. Innovative technology summary report
NONE
1998-11-01
The US Department of Energy's (DOE's) nuclear facility decontamination and decommissioning (D and D) program requires buildings to be decontaminated, decommissioned, and surveyed for radiological contamination in an expeditious and cost-effective manner. Simultaneously, the health and safety of personnel involved in the D and D activities is of primary concern. D and D workers must perform duties high off the ground, requiring the use of manlifts or scaffolding, often, in radiologically or chemically contaminated areas or in areas with limited access. Survey and decontamination instruments that are used are sometimes heavy or awkward to use, particularly when the worker is operating from a manlift or scaffolding. Finding alternative methods of performing such work on manlifts or scaffolding is important. The 2-D Linear Motion System (2-D LMS), also known as the Wall Walker{trademark}, is designed to remotely position tools and instruments on walls for use in such activities as radiation surveys, decontamination, and painting. Traditional (baseline) methods for operating equipment for these tasks require workers to perform duties on elevated platforms, sometimes several meters above the ground surface and near potential sources of contamination. The Wall Walker 2-D LMS significantly improves health and safety conditions by facilitating remote operation of equipment. The Wall Walker 2-D LMS performed well in a demonstration of its precision, accuracy, maneuverability, payload capacity, and ease of use. Thus, this innovative technology is demonstrated to be a viable alternative to standard methods of performing work on large, high walls, especially those that have potential contamination concerns. The Wall Walker was used to perform a final release radiological survey on over 167 m{sup 2} of walls. In this application, surveying using a traditional (baseline) method that employs an aerial lift for manual access was 64% of the total cost of the improved technology. However, for areas over approximately 600 m{sup 2}, the Wall Walker would cost less than the baseline. Using the Wall Walker 2-D LMS, ALARA exposure and worker safety is improved, and there is potential for increased productivity. This innovative technology performed better than the baseline by providing real-time monitoring of the tool or instrument position. Also, the Wall Walker 2-D LMS can traverse any two-dimensional path at constant speeds of up to 18.3 linear meters per minute (60 linear feet per minute). The survey production rate for the innovative technology was about 0.6 m{sup 2}/min (6 ft{sup 2}/min); the baseline production rate was approximately 0.3 m{sup 2}/min (3 ft{sup 2}/min), using the same surveying instrument and maximum scanning rate.
Textile geometry preprocessor for meso-mechanical models of woven composites
S. V. Lomov; A. V. Gusakov; G. Huysmans; A. Prodromou; I. Verpoest
2000-01-01
A mathematical model of the internal geometry of 2D and 3D woven fabrics is used as a unit-cell geometry preprocessor for meso-mechanical models of composite materials. The model computes a spatial placement of all yarns in a fabric repeat for a given weave structure (a special coding algorithm is employed) and given warp and weft yarns geometrical and mechanical parameters.
Koh, Kwi Hye; Pan, Xian; Shen, Hong-Wu; Arnold, Samuel L. M.; Yu, Ai-Ming; Gonzalez, Frank J.; Isoherranen, Nina; Jeong, Hyunyoung
2014-01-01
Substrates of a major drug-metabolizing enzyme CYP2D6 display increased elimination during pregnancy, but the underlying mechanisms are unknown in part due to a lack of experimental models. Here, we introduce CYP2D6-humanized (Tg-CYP2D6) mice as an animal model where hepatic CYP2D6 expression is increased during pregnancy. In the mouse livers, expression of a known positive regulator of CYP2D6, hepatocyte nuclear factor 4? (HNF4?), did not change during pregnancy. However, HNF4? recruitment to CYP2D6 promoter increased at term pregnancy, accompanied by repressed expression of small heterodimer partner (SHP). In HepG2 cells, SHP repressed HNF4? transactivation of CYP2D6 promoter. In transgenic (Tg)-CYP2D6 mice, SHP knockdown led to a significant increase in CYP2D6 expression. Retinoic acid, an endogenous compound that induces SHP, exhibited decreased hepatic levels during pregnancy in Tg-CYP2D6 mice. Administration of all-trans-retinoic acid led to a significant decrease in the expression and activity of hepatic CYP2D6 in Tg-CYP2D6 mice. This study provides key insights into mechanisms underlying altered CYP2D6-mediated drug metabolism during pregnancy, laying a foundation for improved drug therapy in pregnant women. PMID:24318876
NASA Astrophysics Data System (ADS)
Fatanat Didar, Tohid; Dolatabadi, Ali; Wüthrich, Rolf
2008-06-01
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.
On classification of geometries with SO(2,2) symmetry
NASA Astrophysics Data System (ADS)
Sadeghian, S.; Sheikh-Jabbari, M. M.; Yavartanoo, H.
2014-10-01
Motivated by the Extremal Vanishing Horizon (EVH) black holes, their near horizon geometry and the EVH/CFT proposal [1], we construct and classify solutions with (local) SO(2,2) symmetry to four and five dimensional Einstein-Maxwell-Dilaton (EMD) theory with positive, zero or negative cosmological constant ?, the EMD-? theory, and also U(1)4 gauged supergravity in four dimensions and U(1)3 gauged supergravity in five dimensions. In four dimensions the geometries are warped product of AdS3 with an interval or a circle. In five dimensions the geometries are of the form of warped product of AdS3 and a 2d surface ?2. For the Einsten-Maxwell-? theory we prove that ?2 should have a U(1) isometry, a rigidity theorem in this class of solutions. We also construct all d dimensional Einstein vacuum solutions with SO(2,2) × U(1) d-4 isometry.
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
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
Evaluation of imaging geometry for stationary chest tomosynthesis
NASA Astrophysics Data System (ADS)
Shan, Jing; Tucker, Andrew W.; Lee, Yueh Z.; Heath, Michael D.; Wang, Xiaohui; Foos, David; Lu, Jianping; Zhou, Otto
2014-03-01
We have recently demonstrated the feasibility of stationary digital chest tomosynthesis (s-DCT) using a dis- tributed carbon nanotube x-ray source array. The technology has the potential to increase the imaging resolution and speed by eliminating source motion. In addition, the flexibility in the spatial configuration of the individual sources allows new tomosynthesis imaging geometries beyond the linear scanning mode used in the conventional systems. In this paper, we report the preliminary results on the effects of the tomosynthesis imaging geometry on the image quality. The study was performed using a bench-top s-DCT system consisting of a CNT x-ray source array and a flat-panel detector. System MTF and ASF are used as quantitative measurement of the in-plane and in-depth resolution. In this study geometries with the x-ray sources arranged in linear, square, rectangular and circular configurations were investigated using comparable imaging doses. Anthropomorphic chest phantom images were acquired and reconstructed for image quality assessment. It is found that wider angular coverage results in better in-depth resolution, while the angular span has little impact on the in-plane resolution in the linear geometry. 2D source array imaging geometry leads to a more isotropic in-plane resolution, and better in-depth resolution compared to 1D linear imaging geometry with comparable angular coverage.
Wave propagation in pantographic 2D lattices with internal discontinuities
Madeo, A; Neff, P
2014-01-01
In the present paper we consider a 2D pantographic structure composed by two orthogonal families of Euler beams. Pantographic rectangular 'long' waveguides are considered in which imposed boundary displacements can induce the onset of traveling (possibly non-linear) waves. We performed numerical simulations concerning a set of dynamically interesting cases. The system undergoes large rotations which may involve geometrical non-linearities, possibly opening the path to appealing phenomena such as propagation of solitary waves. Boundary conditions dramatically influence the transmission of the considered waves at discontinuity surfaces. The theoretical study of this kind of objects looks critical, as the concept of pantographic 2D sheets seems to have promising possible applications in a number of fields, e.g. acoustic filters, vascular prostheses and aeronautic/aerospace panels.
A Meshless Method for Variational Nonrigid 2-D Shape Registration
Liu, Wei
2011-01-01
We present a method for nonrigid registration of 2-D geometric shapes. Our contribution is twofold. First, we extend the classic chamfer-matching energy to a variational functional. Secondly, we introduce a meshless deformation model that can handle significant high-curvature deformations. We represent 2-D shapes implicitly using distance transforms, and registration error is defined based on the shape contours' mutual distances. In addition, we model global shape deformation as an approximation blended from local deformation fields using partition-of-unity. The global deformation field is regularized by penalizing inconsistencies between local fields. The representation can be made adaptive to shape's contour, leading to registration that is both flexible and efficient. Finally, registration is achieved by minimizing a variational chamfer-energy functional combined with the consistency regularizer. We demonstrate the effectiveness of our method on a number of experiments.
2dF Spectroscopy of M104 Globular Clusters
Terry Bridges; Ken Freeman; Katherine Rhode; Steve Zepf
2002-11-18
We present preliminary results of 2dF spectroscopy of globular clusters in The Sombrero (M104). We find 56 new clusters, and compile a total sample of 103 velocities combined with previous data. Our 2dF data extend out to 20 arcmin radius (~50 kpc), much further than previous studies. In the combined sample, we tentatively find a steep drop in the velocity dispersion with radius, which might possibly indicate a truncated halo. There is no obvious solid-body rotation over all radii, but separate fits for those clusters inside and outside 25 kpc radius show tantalizing evidence for counter-rotation. The projected mass estimator with isotropic orbits yields an M104 mass of 1.2x10^12 solar masses inside 50 kpc, and a (M/L)_B = 30: solid evidence for a dark matter halo in this galaxy.
Visualization of 2-D and 3-D Tensor Fields
NASA Technical Reports Server (NTRS)
Hesselink, Lambertus
1997-01-01
In previous work we have developed a novel approach to visualizing second order symmetric 2-D tensor fields based on degenerate point analysis. At degenerate points the eigenvalues are either zero or equal to each other, and the hyper-streamlines about these points give rise to tri-sector or wedge points. These singularities and their connecting hyper-streamlines determine the topology of the tensor field. In this study we are developing new methods for analyzing and displaying 3-D tensor fields. This problem is considerably more difficult than the 2-D one, as the richness of the data set is much larger. Here we report on our progress and a novel method to find , analyze and display 3-D degenerate points. First we discuss the theory, then an application involving a 3-D tensor field, the Boussinesq problem with two forces.
Visualization of 2-D and 3-D Tensor Fields
NASA Technical Reports Server (NTRS)
Hesselink, Lambertus
1995-01-01
In previous work we have developed a novel approach to visualizing second order symmetric 2-D tensor fields based on degenerate point analysis. At degenerate points the eigenvalues are either zero or equal to each other, and the hyperstreamlines about these points give rise to trisector or wedge points. These singularities and their connecting hyperstreamlines determine the topology of the tensor field. In this study we are developing new methods for analyzing and displaying 3-D tensor fields. This problem is considerably more difficult than the 2-D one, as the richness of the data set is much larger. Here we report on our progress and a novel method to find, analyze and display 3-D degenerate points. First we discuss the theory, then an application involving a 3-D tensor field, the Boussinesq problem with two forces.
Implementation of 2-D DCT based on FPGA
NASA Astrophysics Data System (ADS)
Guo, Bao-Zeng; Niu, Li; Liu, Zhi-Ming
2010-08-01
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.
NSDL National Science Digital Library
1997-01-01
The Geometry Forum is "An Electronic Community for Lovers of Geometry." An NSF-funded project at Swarthmore College, the Geometry Forum is a great place for geometry and math teachers to locate curriculum ideas, software for mathematics, Internet math projects, and information about professional organizations. The student center offers a problem of the week, project of the month, the Internet geometry hunt, student hangouts on the Internet (where students talk about school and math), and students publications. The Geometry Forum has been re-designed and is attractive, easy to navigate, and very friendly. The site is searchable, a Help Desk is included, and the staff is available for questions.
Report of the 1988 2-D Intercomparison Workshop, chapter 3
NASA Technical Reports Server (NTRS)
Jackman, Charles H.; Brasseur, Guy; Soloman, Susan; Guthrie, Paul D.; Garcia, Rolando; Yung, Yuk L.; Gray, Lesley J.; Tung, K. K.; Ko, Malcolm K. W.; Isaken, Ivar
1989-01-01
Several factors contribute to the errors encountered. With the exception of the line-by-line model, all of the models employ simplifying assumptions that place fundamental limits on their accuracy and range of validity. For example, all 2-D modeling groups use the diffusivity factor approximation. This approximation produces little error in tropospheric H2O and CO2 cooling rates, but can produce significant errors in CO2 and O3 cooling rates at the stratopause. All models suffer from fundamental uncertainties in shapes and strengths of spectral lines. Thermal flux algorithms being used in 2-D tracer tranport models produce cooling rates that differ by as much as 40 percent for the same input model atmosphere. Disagreements of this magnitude are important since the thermal cooling rates must be subtracted from the almost-equal solar heating rates to derive the net radiative heating rates and the 2-D model diabatic circulation. For much of the annual cycle, the net radiative heating rates are comparable in magnitude to the cooling rate differences described. Many of the models underestimate the cooling rates in the middle and lower stratosphere. The consequences of these errors for the net heating rates and the diabatic circulation will depend on their meridional structure, which was not tested here. Other models underestimate the cooling near 1 mbar. Suchs errors pose potential problems for future interactive ozone assessment studies, since they could produce artificially-high temperatures and increased O3 destruction at these levels. These concerns suggest that a great deal of work is needed to improve the performance of thermal cooling rate algorithms used in the 2-D tracer transport models.
A 2D Barcode-Based Mobile Payment System
Jerry Gao; Vijay Kulkarni; Himanshu Ranavat; Lee Chang; Hsing Mei
2009-01-01
Mobile payment is very important and critical solution for mobile commerce. A user-friendly mobile payment solution is strongly needed to support mobile users to conduct secure and reliable payment transactions using mobile devices. This paper presents an innovative mobile payment system based on 2-dimensional (2D) barcodes for mobile users to improve mobile user experience in mobile payment.Unlike other existing mobile
The Kubo-Greenwood expression and 2d MIT transport
NASA Astrophysics Data System (ADS)
Castner, Theodore
2010-03-01
The 2d MIT in GaAs heterostructures (p- and n-type)features a mobility that drops continuously as the reduced density x= n/nc-1 is decreased. The Kubo-Greenwood result [1] predicts ? = (e?h/hnc)?^2(x) where ? is a normalized DOS. ?(x)is obtained from the data [p-type, Gao et al. [2]; n-type Lilly et al. [3
Growth of 2D heterostructures of graphene/BN
NASA Astrophysics Data System (ADS)
Hwang, Jeonghyun; Calderon, Brian R.; Alsalman, Hussain A.; Kwak, Joon Young; Kim, Moonkyung; Spencer, Michael G.
2014-06-01
Metal free direct growth of graphene on h-BN using a high temperature (~1550°C) chemical vapor deposition technique was done under Ar environment. Growth temperature, methane partial pressure, hydrogen/methane flow ratio, and growth time were varied and optimized. Raman spectroscopy clearly showed the signature of graphene with G- (~1580cm-1) and 2D-mode (~2700cm-1). The smallest width of G- and 2D-peak was 30 and 55cm-1, respectively, and the Raman I2D/IG ratio varied between 0.7 and 1.8. Raman D-peak (~1350cm-1) shows a strong dependence on growth temperature with the smallest ID/IG value of 0.15 at 1550°C. In the case of long growth, nitrogen and boron doping were detected by x-ray photoelectron spectroscopy with a small Raman D'-peak. A continuous graphene film with the rms roughness (1×1 ?m2 area) of 0.32nm was shown by atomic force microscopy. Early stage of growth revealed circular shaped nucleation islands, the density and heights of which are ~15/?m2 and 1-2 graphene monolayer (ML), respectively. The hydrogen/methane flow ratio was found to be a critical parameter to obtain smooth 2D growth. Growth of h-BN is performed with ammonia borane, hydrogen and Ar. The growth is found to be critically dependent on the conditions of the ammonia boran precursor. Reproducible continuous films of h-BN are reported.
2-D phase unwrapping and instantaneous frequency estimation
Umberto Spagnolini
1995-01-01
The phase of complex signals is wrapped since it can only be measured modulo-2?; unwrapping searches for the 2?-combinations that minimize the discontinuity of the unwrapped phase, as only the unwrapped phase can be analyzed and interpreted by further processing. Given an estimate of the phase gradient (i.e., of the instantaneous frequency), the 2-D unwrapped phase can be obtained as
T. L. Tan; M. G. Gabona; G. B. Lebron
2011-01-01
The Fourier transform infrared (FTIR) absorption spectrum of the nu12 fundamental band of ethylene-d4 (C2D4) was recorded in the 1017-1137 cm-1 region with an unapodized resolution of 0.0063 cm-1. Upper state (v12 = 1) rovibrational constants consisting of three rotational and five quartic constants were improved by assigning and fitting 2103 infrared transitions using Watson's A-reduced Hamiltonian in the Ir
Mock 2dF and SDSS galaxy redshift surveys
Shaun Cole; Steve Hatton; David H. Weinberg; Carlos S. Frenk
1998-01-01
We present a comprehensive set of mock 2dF and SDSS galaxy redshift surveys\\u000aconstructed from a set of large, high-resolution cosmological N-body\\u000asimulations. The radial selection functions and geometrical limits of the\\u000acatalogues mimic those of the genuine surveys. The catalogues span a wide range\\u000aof cosmologies, including both open and flat universes. In all the models the\\u000agalaxy distributions
Fermi liquid parameters of a 2D 3He film
NASA Astrophysics Data System (ADS)
Lusher, C. P.; Saunders, J.; Cowan, B. P.
1990-08-01
A temperature independent magnetic susceptibility has been observed for the second layer of 3He on graphite for second layer surface densities less than 0.055 Å -2, consistent with 2D Fermi liquid behaviour. The Landau parameter Foa is determined using known values of m ?/m. The relative dependence of these two parameters is in good agreement with almost localised Fermion theory, as is the case in bulk liquid 3He.
2-D constrained Navier-Stokes equation and intermediate asymptotics
E. Caglioti; M. Pulvirenti; F. Rousset
2008-07-14
We introduce a modified version of the two-dimensional Navier-Stokes equation, preserving energy and momentum of inertia, which is motivated by the occurrence of different dissipation time scales and related to the gradient flow structure of the 2-D Navier-Stokes equation. The hope is to understand intermediate asymptotics. The analysis we present here is purely formal. A rigorous study of this equation will be done in a forthcoming paper.
Human Face Analysis Based on Distributed 2d Appearance Models
Yasushi Sumi; Yuichi Ohta
1992-01-01
We propose a new framework, called DtTOPS (Dis- tributed Concurrent TOpdown Processing Scheme), for a computer vision system which is suitable in a parallel processing environment. A set of mu1 tiple top-down anal- yses are performed concurrently and distributively. Each of the analyses is based on a different 2D model cam- spanding to a different appearance of a 3D object.
Quantum Motion on 2D Surface of Nonspherical Topology
Q. H. Liu; J. X. Hou; Y. P. Xiao; L. X. Li
2004-01-01
An excess term exists when using hermitian form of Cartesian momentum pi (i = 1, 2, 3) in usual kinetic energy 1\\/(2µ) S pi2 for a particle moving on the 2D surface, and the correct kinetic energy turns to be 1\\/(2µ) S 1\\/fipi fi pi where the fi are dummy factors in classical mechanics and nontrivial in quantum mechanics. In
An Image-Based Shading Pipeline for 2D Animation
Hedlena M. De A. Bezerra; Bruno Feijó; Luiz Velho
2005-01-01
Shading for cel animation based on images is a recent research topic in computer-assisted animation. This paper proposes an image-based shading pipeline to give a 3D ap- pearance to a 2D character by inspecting the hand-drawn image directly. The proposed method estimates normal vec- tors on the character's outline and interpolates them over the remaining image. The method does not
Valley and electric photocurrents in 2D silicon and graphene
Tarasenko, S. A.; Ivchenko, E. L. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Olbrich, P.; Ganichev, S. D. [Terahertz Center, University of Regensburg, 93040 Regensburg (Germany)
2013-12-04
We show that the optical excitation of multi-valley systems leads to valley currents which depend on the light polarization. The net electric current, determined by the vector sum of single-valley contributions, vanishes for some peculiar distributions of carriers in the valley and momentum spaces forming a pure valley current. We report on the study of this phenomenon, both experimental and theoretical, for graphene and 2D electron channels on the silicon surface.
Burgers' equation in 2D SU(N) YM
H. Neuberger
2008-06-30
It is shown that the logarithmic derivative of the characteristic polynomial of a Wilson loop in two dimensional pure Yang Mills theory with gauge group SU(N) exactly satisfies Burgers' equation, with viscosity given by 1/(2N). The Wilson loop does not intersect itself and Euclidean space-time is assumed flat and infinite. This result provides a precise framework in 2D YM for recent observations of Blaizot and Nowak and was inspired by their work.
3D Garment Prototyping from 2D Drawings
Yueqi Zhong; JuanFen Jiang; Zhaoli Wang; Hongyan Liu
\\u000a In this paper, we propose a novel approach to transfer the designer’s 2D drawings into 3D virtual garment. The designer is\\u000a required to provide minimum two silhouettes for the front view and the back view of the original design. The silhouettes are\\u000a triangulated to form a mass-spring system. The virtual sewing of the silhouettes generates the initial shell of the
Improving VERITAS sensitivity by fitting 2D Gaussian image parameters
NASA Astrophysics Data System (ADS)
Christiansen, Jodi; VERITAS Collaboration
2012-12-01
Our goal is to improve the acceptance and angular resolution of VERITAS by implementing a camera image-fitting algorithm. Elliptical image parameters are extracted from 2D Gaussian distribution fits using a ?2 minimization instead of the standard technique based on the principle moments of an island of pixels above threshold. We optimize the analysis cuts and then characterize the improvements using simulations. We find an improvement of 20% less observing time to reach 5-sigma for weak point sources.
Reconstruction of Complex Buildings using LIDAR and 2D Maps
Tee-ann Teo; Jiann-Yeou Raul; Liang-chien Chen; Jin-king Liu; Wei-chen Hsu
2006-01-01
The extraction of the building models from remote-sensed data is an important work in the geographic information systems. This investigation describes an approach to integrate LIDAR data and 2D building boundaries for building reconstruction. The proposed scheme comprises of three major parts: (1) data pre-processing, (2) extraction of building primitive, and (3) shaping. In the data pre-processing, the LIDAR point
Differentiation of C2D Macrophage Cells after Adoptive Transfer
Betsey E. Potts; Marcia L. Hart; Laura L. Snyder; Dan Boyle; Derek A. Mosier; Stephen K. Chapes
2008-01-01
Received 8 August 2007\\/Returned for modification 7 October 2007\\/Accepted 5 December 2007 C2D macrophage cells protect immunocompromised mice from experimentally induced pneumonias after intraperitoneal (i.p.) adoptive transfer. These macrophage cells are immature and display minimal activity in vitro. Therefore, we wanted to understand how adoptive transfer affected these cells. We believe that the in vivo environment affects the phenotypic and
Limit current density in 2D metallic granular packings
NASA Astrophysics Data System (ADS)
Dorbolo, S.; Ausloos, M.; Vandewalle, N.
2003-07-01
The electrical properties of a 2D packed metallic pentagons have been studied. The electrical characterization of such metallic pentagon heaps, like i- V measurements, has been achieved. Two distinct regimes have been shown. They are separated by a transition line along which the system exhibits a memory effect behavior due to the irreversible improvement of electrical contacts between pentagons (hot spots). A limit current density has been found.
Submicrometric 2D ratchet effect in magnetic domain wall motion
NASA Astrophysics Data System (ADS)
Castán-Guerrero, C.; Herrero-Albillos, J.; Sesé, J.; Bartolomé, J.; Bartolomé, F.; Hierro-Rodriguez, A.; Valdés-Bango, F.; Martín, J. I.; Alameda, J. M.; García, L. M.
2014-12-01
Strips containing arrays of submicrometric triangular antidots with a 2D square periodicity have been fabricated by electron beam lithography. A clear ratchet effect of 180° domain wall motion under a varying applied field parallel to the walls has been observed. The direction is determined by the direction of the triangle vertices. In contrast, no ratchet effect is observed when the antidot array is constituted by symmetric rhomb-shaped antidots.
Electronic and magnetic properties of 2D BCN nanostructures
NASA Astrophysics Data System (ADS)
Park, Hyoungki
2013-03-01
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.
NASA High-Speed 2D Photogrammetric Measurement System
NASA Technical Reports Server (NTRS)
Dismond, Harriett R.
2012-01-01
The object of this report is to provide users of the NASA high-speed 2D photogrammetric measurement system with procedures required to obtain drop-model trajectory and impact data for full-scale and sub-scale models. This guide focuses on use of the system for vertical drop testing at the NASA Langley Landing and Impact Research (LandIR) Facility.
High precision calibration for 2D optical standard
NASA Astrophysics Data System (ADS)
Sun, Shuanghua; Gan, Xiaochuan; Xue, Zi; Ye, Xiaoyou; Wang, Heyan; Gao, Hongtang
2012-10-01
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).
An Intercomparison of 2-D Models Within a Common Framework
NASA Technical Reports Server (NTRS)
Weisenstein, Debra K.; Ko, Malcolm K. W.; Scott, Courtney J.; Jackman, Charles H.; Fleming, Eric L.; Considine, David B.; Kinnison, Douglas E.; Connell, Peter S.; Rotman, Douglas A.; Bhartia, P. K. (Technical Monitor)
2002-01-01
A model intercomparison among the Atmospheric and Environmental Research (AER) 2-D model, the Goddard Space Flight Center (GSFC) 2-D model, and the Lawrence Livermore National Laboratory 2-D model allows us to separate differences due to model transport from those due to the model's chemical formulation. This is accomplished by constructing two hybrid models incorporating the transport parameters of the GSFC and LLNL models within the AER model framework. By comparing the results from the native models (AER and e.g. GSFC) with those from the hybrid model (e.g. AER chemistry with GSFC transport), differences due to chemistry and transport can be identified. For the analysis, we examined an inert tracer whose emission pattern is based on emission from a High Speed Civil Transport (HSCT) fleet; distributions of trace species in the 2015 atmosphere; and the response of stratospheric ozone to an HSCT fleet. Differences in NO(y) in the upper stratosphere are found between models with identical transport, implying different model representations of atmospheric chemical processes. The response of O3 concentration to HSCT aircraft emissions differs in the models from both transport-dominated differences in the HSCT-induced perturbations of H2O and NO(y) as well as from differences in the model represent at ions of O3 chemical processes. The model formulations of cold polar processes are found to be the most significant factor in creating large differences in the calculated ozone perturbations
A 2D model for a gliding arc discharge
NASA Astrophysics Data System (ADS)
Kolev, St.; Bogaerts, A.
2015-02-01
In this study we report on a 2D fluid model of a gliding arc discharge in argon. Despite the 3D nature of the discharge, 2D models are found to be capable of providing very useful information about the operation of the discharge. We employ two models—an axisymmetric and a Cartesian one. We show that for the considered experiment and the conditions of a low current arc (around 30 mA) in argon, there is no significant heating of the cathode surface and the discharge is sustained by field electron emission from the cathode accompanied by the formation of a cathode spot. The obtained discharge power and voltage are relatively sensitive to the surface properties and particularly to the surface roughness, causing effectively an amplification of the normal electric field. The arc body and anode region are not influenced by this and depend mainly on the current value. The gliding of the arc is modelled by means of a 2D Cartesian model. The arc–electrode contact points are analysed and the gliding mechanism along the electrode surface is discussed. Following experimental observations, the cathode spot is simulated as jumping from one point to another. A complete arc cycle is modelled from initial ignition to arc decay. The results show that there is no interaction between the successive gliding arcs.
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
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
Euclidean geometry as algorithm for construction of generalized geometries
Yuri A. Rylov
2005-01-01
It is shown that the generalized geometries may be obtained as a deformation\\u000aof the proper Euclidean geometry. Algorithm of construction of any proposition\\u000aS of the proper Euclidean geometry E may be described in terms of the Euclidean\\u000aworld function sigma_E in the form S(sigma_E). Replacing the Euclidean world\\u000afunction sigma_E by the world function sigma of the geometry
Tobias Vollmar; Baerbel Maus; Rolf P. Wurtz; Gabriele Gillessen-Kaesbach; Bernhard Horsthemke; Dagmar Wieczorek; Stefan Boehringer
2008-01-01
Digital image analysis of faces has been demonstrated to be effective in a small number of syndromes. In this paper we investigate several aspects that help bringing these methods closer to clinical application. First, we investigate the impact of increasing the number of syndromes from 10 to 14 as compared to an earlier study. Second, we include a side-view pose
hal-00137965,version1-25Mar2007 A distributional approach to the geometry of 2D
Boyer, Edmond
relating the incompatibility tensor to the Frank and Burgers vectors are proved under global strain has a constant Burgers vector which exhibits additive properties at dislocation junctions;Aware of these principles and of the pioneer works of Volterra (1907) and Cosserat (1909), Burgers (1939
A 2D block-structured mesh partitioner for accurate flow simulations on non-rectangular geometries
E. Ahusborde; S. Glockner
2011-01-01
The motivation of this work is to carry out parallel simulations of incompressible flows on block-structured meshes. A new partitioning method is proposed. The quality of rectangular partitions is checked and compared with other methods, as regards load balance, edge-cut and block numbers. The partitioner is coupled with the massively parallel Hypre solver library and efficiency of the coupling is
Sebastian Schunert; Yousry Y. Azmy; Damien Fournier
2011-05-01
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.
NASA Technical Reports Server (NTRS)
Hua, Chongyu; Volakis, John L.
1990-01-01
AUTOMESH-2D is a computer program specifically designed as a preprocessor for the scattering analysis of two dimensional bodies by the finite element method. This program was developed due to a need for reproducing the effort required to define and check the geometry data, element topology, and material properties. There are six modules in the program: (1) Parameter Specification; (2) Data Input; (3) Node Generation; (4) Element Generation; (5) Mesh Smoothing; and (5) Data File Generation.
M. V. Umansky; B LaBombard
1999-01-01
A new 2-D interpretive code for the tokamak edge plasma, EDGEFIT, has been developed. It infers the anomalous cross-field heat diffusivity, ?, in the scrape-off layer (SOL) of Alcator C-Mod from the experimental data solving the heat conduction equation in the real magnetic geometry. Measurements of temperature from the Langmuir probes on the divertor target plates are used for setting
G. Villalobos; D. L. Linero; J. D. Munoz
2010-02-22
A 2D, hexagonal in geometry, statistical model of fracture is proposed. The model is based on the drying fracture process of the bamboo Guadua angustifolia. A network of flexible cells are joined by brittle junctures of different Young moduli that break at a fixed threshold in tensile force. The system is solved by means of the Finite Element Method (FEM). The distribution of avalanche breakings exhibits a power law with exponent -2.93(9), in agreement with the random fuse model.
Abstract. Geometry and Complex Numbers GEOMETRY AND COMPLEX NUMBERS
Lee, Carl
Abstract. Geometry and Complex Numbers GEOMETRY AND COMPLEX NUMBERS JERZY DYDAK Contents 1. Introduction 2 2. Solving equations 10 3. Geometric proofs 20 Key words and phrases. Complex numbers. 1 #12-Euclidean, Projective, and Discrete' by Michael Henle (2nd edition, Prentice Hall). (2) `Complex numbers and geometry
Cylindrical geometry hall thruster
Raitses, Yevgeny (Princeton, NJ); Fisch, Nathaniel J. (Princeton, NJ)
2002-01-01
An apparatus and method for thrusting plasma, utilizing a Hall thruster with a cylindrical geometry, wherein ions are accelerated in substantially the axial direction. The apparatus is suitable for operation at low power. It employs small size thruster components, including a ceramic channel, with the center pole piece of the conventional annular design thruster eliminated or greatly reduced. Efficient operation is accomplished through magnetic fields with a substantial radial component. The propellant gas is ionized at an optimal location in the thruster. A further improvement is accomplished by segmented electrodes, which produce localized voltage drops within the thruster at optimally prescribed locations. The apparatus differs from a conventional Hall thruster, which has an annular geometry, not well suited to scaling to small size, because the small size for an annular design has a great deal of surface area relative to the volume.
Failures of information geometry
NASA Astrophysics Data System (ADS)
Skilling, John
2015-01-01
Information H is a unique relationship between probabilities, based on the property of independence which is central to scientific methodology. Information Geometry makes the tempting but fallacious assumption that a local metric (conventionally based on information) can be used to endow the space of probability distributions with a preferred global Riemannian metric. No such global metric can conform to H, which is "from-to" asymmetric whereas geometrical length is by definition symmetric. Accordingly, any Riemannian metric will contradict the required structure of the very distributions which are supposedly being triangulated. It follows that probabilities do not form a metric space. We give counter-examples in which alternative formulations of information, and the use of information geometry, lead to unacceptable results.
ccsd00001948, 2D potential structures induced by RF sheaths
appear during a shot. In typical Tore Supra conditions near antenna corners potential structures less will be useful to obtain the potential structures in front of each part of the complex antenna's geometry antenna has been #28;rstly mo- tivated by the apparition, on antenna structure, of hot spots [1] [2
Freezing in confined geometries
NASA Technical Reports Server (NTRS)
Sokol, P. E.; Ma, W. J.; Herwig, K. W.; Snow, W. M.; Wang, Y.; Koplik, Joel; Banavar, Jayanth R.
1992-01-01
Results of detailed structural studies, using elastic neutron scattering, of the freezing of liquid O2 and D2 in porous vycor glass, are presented. The experimental studies have been complemented by computer simulations of the dynamics of freezing of a Lennard-Jones liquid in narrow channels bounded by molecular walls. Results point to a new simple physical interpretation of freezing in confined geometries.
Computational Geometry - A Survey
D. T. Lee; Franco P. Preparata
1984-01-01
We survey thestate oftheartofcomputational geometry, adiscipline that deals withthecomplexity ofgeometric problems within theframework oftheanalysis ofalgorithms. This newly emerged areaofactivities hasfound numerous applications invarious otherdisciplines, suchascomputer-aided design, computer graphics, operations research, pattern recognition, robotics, andstatistics. Fivemajorproblem areas -convex hulls, intersections, searching, proximity, andcombinatorial opti- mizations - arediscussed. Sevenalgorithmic techniques incremental construction, plane-sweep, locus, divide-and- conquer, geometric transformation, prune-and-search, and dynamization -
NON COMMUTATIVE DIFFERENTIAL GEOMETRY
Michel Dubois-Violette; Peter W. Michor
In commutative differential geometry the Frolicher-Nijenhuis bracket computes all kinds of curvatures and obstructions to integrability. In (1) the Frolicher- Nijenhuis bracket was developed for universal differential forms of non-commutative algebras, and several applications were given. In this paper this bracket and the Frolicher-Nijenhuis calculus will be developed for several kinds of differential graded algebras based on derivations, which were
Fuzzy Boundary Control of 2D Burgers Equation with an Observer Mehmet Onder Efe
Efe, Mehmet Ã?nder
u with u being 2-by-1 vector function is described as the 2D Burgers equation. The 2D BurgersFuzzy Boundary Control of 2D Burgers Equation with an Observer Mehmet Â¨Onder Efe Abstract-- Fuzzy boundary control of 2D Burgers Equation is considered in this paper. The Burgers equation has extensively
New Design of Integrated 2D Photonic Crystal Narrow Band Filters Using the FDTD-2D Method
NASA Astrophysics Data System (ADS)
Badaoui, Hadjira Abri; Abri, Mehadji
2014-11-01
In this paper, integrated 2D photonic crystal narrow band filter design is achieved based on transmission spectra shift. The presented effective technique for the design of narrow band resonant filters obtained by one-missing-row and by choosing proper radii of air holes of the waveguide is proposed. The 2D photonic crystals are designed by utilizing cascaded waveguides with different radii of air holes. The results are presented for normal incident wave with TE polarizations with a narrow spectral bandwidth centered at ? = 1.55 ?m. We also discuss the filtering process and its necessary modifications to achieve efficient filtering. A final synthesized filter topology is presented and a band from 1.53 ?m to 1.57 ?m around 1.55 ?m is transmitted with a maximum transmission of about 77% with better performances is achieved.
Projective geometry with Clifford algebra
David Hestenes; Renatus Ziegler
1991-01-01
Projective geometry is formulated in the language of geometric algebra, a unified mathematical language based on Clifford algebra. This closes the gap between algebraic and synthetic approaches to projective geometry and facilitates connections with the rest of mathematics.
Geometry for the Secondary School
ERIC Educational Resources Information Center
Moalem, D.
1977-01-01
A sequential but non-axiomatic high school geometry course which includes Euclidean, transformation, and analytic geometry and vectors and matrices, and emphasizes the invariance property of transformations, is outlined. Sample problems, solutions, and comments are included. (MN)
The CSMP Development of Geometry
ERIC Educational Resources Information Center
Educational Studies in Mathematics, 1971
1971-01-01
A tentative approach to geometry by the Comprehensive School Mathematics Program (CSMP) is discussed. Included are descriptions of the content for courses in the elementary, middle, and secondary school mathematics. Both Euclidean and affine plane geometry are included. (JG)
A Lorentz Covariant Noncommutative Geometry
A. Lewis Licht
2005-12-13
A noncommutative geometry that preserves lorentz covariance was introduced by Hartland Snyder in 1947. We show that this geometry has unusual properties under momentum translation, and derive for it a form of star product.
Koh, Kwi Hye; Pan, Xian; Zhang, Wei; McLachlan, Alan; Urrutia, Raul; Jeong, Hyunyoung
2014-12-01
Cytochrome P450 2D6 (CYP2D6), a major drug-metabolizing enzyme, is responsible for metabolism of approximately 25% of marketed drugs. Clinical evidence indicates that metabolism of CYP2D6 substrates is increased during pregnancy, but the underlying mechanisms remain unclear. To identify transcription factors potentially responsible for CYP2D6 induction during pregnancy, a panel of genes differentially expressed in the livers of pregnant versus nonpregnant CYP2D6-humanized (tg-CYP2D6) mice was compiled via microarray experiments followed by real-time quantitative reverse-transcription polymerase chain reaction(qRT-PCR) verification. As a result, seven transcription factors-activating transcription factor 5 (ATF5), early growth response 1 (EGR1), forkhead box protein A3 (FOXA3), JUNB, Krüppel-like factor 9 (KLF9), KLF10, and REV-ERB?-were found to be up-regulated in liver during pregnancy. Results from transient transfection and promoter reporter gene assays indicate that KLF9 itself is a weak transactivator of CYP2D6 promoter but significantly enhances CYP2D6 promoter transactivation by hepatocyte nuclear factor 4 (HNF4?), a known transcriptional activator of CYP2D6 expression. The results from deletion and mutation analysis of CYP2D6 promoter activity identified a KLF9 putative binding motif at -22/-14 region to be critical in the potentiation of HNF4?-induced transactivation of CYP2D6. Electrophoretic mobility shift assays revealed a direct binding of KLF9 to the putative KLF binding motif. Results from chromatin immunoprecipitation assay showed increased recruitment of KLF9 to CYP2D6 promoter in the livers of tg-CYP2D6 mice during pregnancy. Taken together, our data suggest that increased KLF9 expression is in part responsible for CYP2D6 induction during pregnancy via the potentiation of HNF4? transactivation of CYP2D6. PMID:25217496
NASA Astrophysics Data System (ADS)
Mikellides, I. G.; Tassis, K.; Yorke, H. W.
2011-02-01
The mechanisms that maintain thermal balance in the intracluster medium (ICM) and produce the observed spatial distribution of the plasma density and temperature in galaxy clusters remain a subject of debate. We present results from numerical simulations of the cooling-core cluster A2199 produced by the 2D resistive magnetohydrodynamics (MHD) code MACH2. In our simulations we explore the effect of anisotropic thermal conduction on the energy balance of the system. The results from idealized cases in 2D axisymmetric geometry underscore the importance of the initial plasma density in ICM simulations, especially the near-core values since the radiation cooling rate is proportional to ne2. Heat conduction is found to be non-effective in preventing catastrophic cooling in this cluster. In addition we performed 2D planar MHD simulations starting from initial conditions deliberately violating both thermal balance and hydrostatic equilibrium in the ICM, to assess contributions of the convective terms in the energy balance of the system against anisotropic thermal conduction. We find that in this case work done by the pressure on the plasma can dominate the early evolution of the internal energy over anisotropic thermal conduction in the presence of subsonic flows, thereby reducing the impact of the magnetic field. Deviations from hydrostatic equilibrium near the cluster core may be associated with transient activity of a central active galactic nucleus and/or remnant dynamical activity in the ICM and warrant further study in three dimensions.
Ren, Shiwei; Ma, Xiaochuan; Yan, Shefeng; Hao, Chengpeng
2013-01-01
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. PMID:23539031
NASA Astrophysics Data System (ADS)
Filik, Tansu; Tuncer, T. Engin
2010-06-01
A new technique is proposed for the solution of pairing problem which is observed when fast algorithms are used for two-dimensional (2-D) direction-of-arrival (DOA) estimation. Proposed method is integrated with array interpolation for efficient use of antenna elements. Two virtual arrays are generated which are positioned accordingly with respect to the real array. ESPRIT algorithm is used by employing both the real and virtual arrays. The eigenvalues of the rotational transformation matrix have the angle information at both magnitude and phase which allows the estimation of azimuth and elevation angles by using closed-form expressions. This idea is used to obtain the paired interpolated ESPRIT algorithm which can be applied for arbitrary arrays when there is no mutual coupling. When there is mutual coupling, two approaches are proposed in order to obtain 2-D paired DOA estimates. These blind methods can be applied for the array geometries which have mutual coupling matrices with a Toeplitz structure. The first approach finds the 2-D paired DOA angles without estimating the mutual coupling coefficients. The second approach estimates the coupling coefficients and iteratively improves both the coupling coefficients and the DOA estimates. It is shown that the proposed techniques solve the pairing problem for uniform circular arrays and effectively estimate the DOA angles in case of unknown mutual coupling.
About the Efficiency of Numerical 1-D and 2-D Modelling of Site Effects in Basin Structures
NASA Astrophysics Data System (ADS)
Riepl, J.; Zahradník, J.; Plicka, V.; Bard, P.-Y.
In the present study we compare results obtained from experimental estimates of local site amplification effects with those from numerical modelling using four different techniques. We benefit from an extremely precise knowledge of the near-surface structure and experimental estimates of the local amplification factors which are determined from seismic weak-motion data recorded by a dense array across a sedimentary basin at a European test-site in Northern Greece. The possibilities and limitations of the different modelling techniques (a 1-D technique, and three 2-D techniques) to model the effects of local amplification effects are tested. Amplifications calculated by the numerical techniques are only qualitatively compared with observed data from experimental studies in the time domain and directly in the frequency domain.As a result we conclude that, in the case of a complex subsurface geometry, 1-D modelling underestimates the amplification patterns in terms of absolute amplification level, and cannot correctly account for resonant frequencies, at least for modes higher than the fundamental mode. If a more realistic incident wave field than just a plane wave is taken into account, 2-D modelling reveals the fundamental frequency and shows adequate amplifications not only at the fundamental frequency but also at higher frequencies. The general trend of the amplifications at the lowest frequencies is well determined by the 2-D numerical modelling, and can therefore supply information for seismic risk analysis.
Geometry in Cryptography Luca Giuzzi
Giuzzi, Luca
, then compute h = g2 and return g · hk. Luca Giuzzi -- Geometry in Cryptography 10 #12;Elliptic curves/1 - ). Luca Giuzzi -- Geometry in Cryptography 11 #12;Elliptic curves/2 Elliptic curve over GF(2n): · non in Cryptography 12 #12;Elliptic curves/3:group law placements A B -(A + B) A + B 0 Luca Giuzzi -- Geometry
Computer-Aided Geometry Modeling
NASA Technical Reports Server (NTRS)
Shoosmith, J. N. (compiler); Fulton, R. E. (compiler)
1984-01-01
Techniques in computer-aided geometry modeling and their application are addressed. Mathematical modeling, solid geometry models, management of geometric data, development of geometry standards, and interactive and graphic procedures are discussed. The applications include aeronautical and aerospace structures design, fluid flow modeling, and gas turbine design.
Graded geometry and Poisson reduction
Cattaneo, A. S. [Institut fuer Mathematik, Universitaet Zuerich-Irchel, Winterthurerstr. 190, CH-8057 Zuerich (Switzerland); Zambon, M. [Centre de Recerca Matematica, Apartat de correus 50, 08193 Bellaterra (Spain)
2009-02-02
The main result extends the Marsden-Ratiu reduction theorem in Poisson geometry, and is proven by means of graded geometry. In this note we provide the background material about graded geometry necessary for the proof. Further, we provide an alternative algebraic proof for the main result.
ERIC Educational Resources Information Center
Instructional Objectives Exchange, Los Angeles, CA.
Behavioral objectives, each accompanied by six sample test items, for secondary school geometry are presented. Objectives were determined by surveying the most widely used secondary school geometry textbooks, and cover 14 major categories of geometry, with sections on set theory and introductory trigonometry. Answers are provided. Categories…
The geometry package Hideo Umeki
Gkioulekas, Eleftherios - Department of Mathematics, University of Texas
The geometry package Hideo Umeki hideo.umeki@toshiba.co.jp 1999/10/07 (v2.2) Abstract This package. Contents 1 Preface to Version 2 1 2 Introduction 2 3 Page Geometry 2 3.1 Layout Dimensions . . . . . . 2 3: · The geometry options using the keyval scheme can be set in the optional argument to the \\usepackage command
TOF Geometry TOF Software Review
Llope, William J.
TOF Geometry W.J. Llope TOF Software Review Nov. 2008, BNL · the "jigsaw puzzle" · simple acceptance simulation · final tray-local geometry · installed tray locations · many ~20mil effects from manufacturing tolerances · upVPD-local geometry · geant simulations · positioning · summary #12
Geometry, noncommutative algebra and representations
Gordon, Iain
Geometry, noncommutative algebra and representations Iain Gordon http://www.maths.ed.ac.uk/~igordon/ University of Edinburgh 16th December 2006 1 Iain Gordon Geometry, noncommutative algebra and representations Outline 1 Geometry and Commutative Algebra 2 Singularities and Resolutions 3 Noncommutative Algebra
Geometry Textures Rodrigo de Toledo
Paris-Sud XI, Université de
Geometry Textures Rodrigo de Toledo Tecgraf PUC-Rio Rio de Janeiro - RJ, Brasil rtoledo but applied to the whole object. Tessel- lated models are converted into geometry textures, a geo- metric with LOD speed-up while preserving original quality. 1 Introduction The goal of geometry textures
A novel time dependent gamma evaluation function for dynamic 2D and 3D dose distributions
NASA Astrophysics Data System (ADS)
Podesta, Mark; CGG Persoon, Lucas; Verhaegen, Frank
2014-10-01
Modern external beam radiotherapy requires detailed verification and quality assurance so that confidence can be placed on both the delivery of a single treatment fraction and on the consistency of delivery throughout the treatment course. To verify dose distributions, a comparison between prediction and measurement must be made. Comparisons between two dose distributions are commonly performed using a Gamma evaluation which is a calculation of two quantities on a pixel by pixel basis; the dose difference, and the distance to agreement. By providing acceptance criteria (e.g. 3%, 3?mm), the function will find the most appropriate match within its two degrees of freedom. For complex dynamic treatments such as IMRT or VMAT it is important to verify the dose delivery in a time dependent manner and so a gamma evaluation that includes a degree of freedom in the time domain via a third parameter, time to agreement, is presented here. A C++ (mex) based gamma function was created that could be run on either CPU and GPU computing platforms that would allow a degree of freedom in the time domain. Simple test cases were created in both 2D and 3D comprising of simple geometrical shapes with well-defined boundaries varying over time. Changes of varying magnitude in either space or time were introduced and repeated gamma analyses were performed varying the criteria. A clinical VMAT case was also included, artificial air bubbles of varying size were introduced to a patient geometry, along with shifts of varying magnitude in treatment time. For all test cases where errors in distance, dose or time were introduced, the time dependent gamma evaluation could accurately highlight the errors. The time dependent gamma function presented here allows time to be included as a degree of freedom in gamma evaluations. The function allows for 2D and 3D data sets which are varying over time to be compared using appropriate criteria without penalising minor offsets of subsequent radiation fields in time.
Stephan Heuel; Wolfgang Förstner
2001-01-01
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
Two-fluid magnetic island dynamics in slab geometry: I -Isolated islands
Fitzpatrick, Richard
Two-fluid magnetic island dynamics in slab geometry: I - Isolated islands Richard Fitzpatrick at Austin Austin, TX 78712 A set of reduced, 2-D, two-fluid, drift-MHD (magnetohydrodynami- cal) equations magnetic island propagating through a slab plasma with uniform but different ion and electron fluid veloc
Two-fluid magnetic island dynamics in slab geometry Richard Fitzpatrick
Fitzpatrick, Richard
Two-fluid magnetic island dynamics in slab geometry Richard Fitzpatrick and FranÂ¸cois L. Waelbroeck set of reduced, 2-D, two-fluid, drift-MHD (magnetohydrody- namical) equations is derived. Using propagating through a slab plasma with uniform but different ion and electron fluid veloc- ities. The ion
Semi-automatic abdominal aortic aneurysms geometry assessment based on 3D ultrasound
Paris-Sud XI, UniversitÃ© de
Semi-automatic abdominal aortic aneurysms geometry assessment based on 3D ultrasound Laurence Rouet of the size of abdominal aortic aneurysms (AAA). Use of 3D ultrasound imaging combined with semi% of the cases. The standard surveillance of AAA consists in monitoring its maximum diameter using 2D ultrasound
NASA Astrophysics Data System (ADS)
Tan, T. L.; Gabona, M. G.; Lebron, G. B.
2011-04-01
The Fourier transform infrared (FTIR) absorption spectrum of the ?12 fundamental band of ethylene- d4 (C 2D 4) was recorded in the 1017-1137 cm -1 region with an unapodized resolution of 0.0063 cm -1. Upper state ( v12 = 1) rovibrational constants consisting of three rotational and five quartic constants were improved by assigning and fitting 2103 infrared transitions using Watson's A-reduced Hamiltonian in the I r representation. The band centre of the A-type ?12 band is found to be 1076.98480 ± 0.00002 cm -1. The present analysis covering a wider wavenumber range and higher J and K c values yielded upper state constants including the band centre which are more accurate than previously reported. The rms deviation of the upper state fit is 0.00045 cm -1. Improved ground state rovibrational constants were also determined from the fit of 1247 ground state combination differences (GSCD) from the presently-assigned infrared transitions of the ?12 band of C 2D 4. The rms deviation of the GSCD fit is 0.00049 cm -1. In the rovibrational analysis, local frequency perturbations were not detected even at high J and K a values. The calculated inertial defect ? 12 is 0.32551 ± 0.00001 ?Å 2. The line intensities of the individual transitions in the ?12 band were measured and the band strength of 39.8 ± 2.0 cm -2 atm -1 was derived for the ?12 band of C 2D 4.
Efficient 2D inversion of long ERT sections
NASA Astrophysics Data System (ADS)
Tsourlos, Panagiotis; Papadopoulos, Nikos; Papazachos, Costas; Yi, Myeong-Jong; Kim, Jung-Ho
2014-06-01
In this work a new algorithm for the efficient and fast two dimensional (2D) inversion of long electrical resistivity tomography (ERT) sections is introduced. The algorithm is based on 2.5D finite element method (FEM) scheme to solve Poisson's equation that describes the current flow into the earth's subsurface. The adjoint equation technique was incorporated into the FEM framework to estimate the sensitivity values. The reconstructed 2D resistivity models are recovered through an iterative, non-linear smoothness constrained least-squares approach. The algorithm further incorporates an experimental procedure to avoid the calculation and storage of the entire Jacobian matrix. The basic concept of this new algorithm relies on the fact that for every measurement there is a number of model parameters which are located in parts of the 2-D model at distant locations from potential and current electrodes. The corresponding absolute Jacobian matrix values in such cases are very small (almost zero) and can be omitted by the Jacobian calculation. Around every measurement a fixed rectangular threshold region is defined a-priori based on geometrical criteria. The algorithm calculates only Jacobian matrix values for the model parameters that are included in this threshold area omitting the calculation of the Jacobian entries related to model parameters outside this region. This approach speeds up the Jacobian matrix calculations while the efficient storage of the sparse Jacobian and Smoothness matrices and the inversion using an iterative routine like LSQR method increase significantly the inversion speed and reduce the memory requirements. The new algorithm is almost more than one order of magnitude (~ 30 times) faster and consumes one order of magnitude (~ 90%) less storage memory than the original one based on full Jacobian calculations for typical applications. The application of the new algorithm to synthetic and real data sets shows that the reconstructed models exhibit comparable accuracy to the standard inversion approach.
Endoscopic navigation system using 2D/3D registration
NASA Astrophysics Data System (ADS)
Hummel, Johann; Figl, Michael; Bergmann, Helmar; Birkfellner, Wolfgang
2006-03-01
The paper describes a computer-aided navigation system using image fusion to support endoscopic intervention like accurate collection of biopsy specimen. In particular, an endoscope which provides the physician with real time ultrasound (US) and a video image, is equipped with an electromagnetic tracking sensor. An image slice that corresponds to the actual image of the US scan head is derived from a preoperative computed tomography (CT) volume data set by means of oblique reformatting. Both views are displayed side by side. The position of the image acquired by the US scanhead is determined by the miniatured electromagnetic tracking system (EMTS) after applying a calibration to the endoscope's scanhead. The relative orientation between the patient coordinate system and a preoperative dataset (such CT or magnetic resonance (MR) image) is derived from a 2D/3D registration. This was achieved by calibrating an interventional CT slice by means of an optical tracking system (OTS) using the same algorithm as for the US calibration. Then the interventional CT slice is used for a 2D/3D registration into the coordinate system of the preoperative CT. The fiducial registration error (FRE) for the US calibration amounted to 3.6 mm +/- 2.0 mm. For the interventional CT we found a FRE of 0.36 +/- 0.12 mm. The error for the 2D/3D registration was 2.3 +/- 0.5 mm. The point-to-point registration between to OTS and the EMTS was accomplished with an FRE of 0.6 mm.
Human erythrocytes analyzed by generalized 2D Raman correlation spectroscopy
NASA Astrophysics Data System (ADS)
Wese?ucha-Birczy?ska, Aleksandra; Kozicki, Mateusz; Czepiel, Jacek; ?abanowska, Maria; Nowak, Piotr; Kowalczyk, Grzegorz; Kurdziel, Magdalena; Birczy?ska, Malwina; Biesiada, Gra?yna; Mach, Tomasz; Garlicki, Aleksander
2014-07-01
The most numerous elements of the blood cells, erythrocytes, consist mainly of two components: homogeneous interior filled with hemoglobin and closure which is the cell membrane. To gain insight into their specific properties we studied the process of disintegration, considering these two constituents, and comparing the natural aging process of human healthy blood cells. MicroRaman spectra of hemoglobin within the single RBC were recorded using 514.5, and 785 nm laser lines. The generalized 2D correlation method was applied to analyze the collected spectra. The time passed from blood donation was regarded as an external perturbation. The time was no more than 40 days according to the current storage limit of blood banks, although, the average RBC life span is 120 days. An analysis of the prominent synchronous and asynchronous cross peaks allow us to get insight into the mechanism of hemoglobin decomposition. Appearing asynchronous cross-peaks point towards globin and heme separation from each other, while synchronous shows already broken globin into individual amino acids. Raman scattering analysis of hemoglobin “wrapping”, i.e. healthy erythrocyte ghosts, allows for the following peculiarity of their behavior. The increasing power of the excitation laser induced alterations in the assemblage of membrane lipids. 2D correlation maps, obtained with increasing laser power recognized as an external perturbation, allows for the consideration of alterations in the erythrocyte membrane structure and composition, which occurs first in the proteins. Cross-peaks were observed indicating an asynchronous correlation between the senescent-cell antigen (SCA) and heme or proteins vibrations. The EPR spectra of the whole blood was analyzed regarding time as an external stimulus. The 2D correlation spectra points towards participation of the selected metal ion centers in the disintegration process.
Apparent 2-D diffusivity in a ruffled cell membrane.
King, Michael R
2004-04-01
Most biological cell membranes have a microtopology that increases their surface area, including a highly ruffled surface in the case of leukocytes. Thus, molecular membrane diffusivities as measured by fluorescence recovery after photobleaching or other methods are decreased when projected onto a plane. We use a two-dimensional crested cycloid as a parameterized surface to simulate the random-walk diffusion of a molecule within a ruffled membrane. The apparent 2-D diffusivity was then calculated when the ruffled membrane is projected onto a plane. It is shown that the apparent diffusivity decreases as a function of the membrane area, to the -1.4 power. PMID:15019499
Exact solutions for the 2d one component plasma
Timothy D. Andersen
2013-02-13
The 2d one component gas of pointlike charges in a uniform neutralizing background interacting with a logarithmic potential is a common model for plasmas. In its classical equilibrium statistics at fixed temperature (canonical ensemble) it is formally related to certain types of random matrices with Gaussian distribution and complex eigenvalues. In this paper, I present an exact integration of this ensemble for $N$ such particles (or alternatively $N\\times N$ matrices) for all even non-negative temperatures, a significant open problem in statistical physics for several decades. I achieve this exact integration via an exact integration of a related ensemble, the two-dimensional Selberg integral.