Behavioral analysis of anisotropic diffusion in image processing

©1996 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.DOI: 10.1109/83.541424In this paper, we analyze the behavior of the anisotropic diffusion model of Perona and Malik (1990). The main idea is to express the anisotropic diffusion equation as coming from a certain optimization problem, so its behavior can be analyzed based on the shape of the corresponding energy surface. We show that anisotropic diffusion is the steepest descent method for solving an energy minimization problem. It is demonstrated that an anisotropic diffusion is well posed when there exists a unique global minimum for the energy functional and that the ill posedness of a certain anisotropic diffusion is caused by the fact that its energy functional has an infinite number of global minima that are dense in the image space. We give a sufficient condition for an anisotropic diffusion to be well posed and a sufficient and necessary condition for it to be ill posed due to the dense global minima. The mechanism of smoothing and edge enhancement of anisotropic diffusion is illustrated through a particular orthogonal decomposition of the diffusion operator into two parts: one that diffuses tangentially to the edges and therefore acts as an anisotropic smoothing operator, and the other that flows normally to the edges and thus acts as an enhancement operator

A viral CTL escape mutation leading to immunoglobulin-like transcript 4-mediated functional inhibition of myelomonocytic cells

Viral mutational escape can reduce or abrogate recognition by the T cell receptor (TCR) of virus-specific CD8+ T cells. However, very little is known about the impact of cytotoxic T lymphocyte (CTL) epitope mutations on interactions between peptide–major histocompatibility complex (MHC) class I complexes and MHC class I receptors expressed on other cell types. Here, we analyzed a variant of the immunodominant human leukocyte antigen (HLA)-B2705–restricted HIV-1 Gag KK10 epitope (KRWIILGLNK) with an L to M amino acid substitution at position 6 (L6M), which arises as a CTL escape variant after primary infection but is sufficiently immunogenic to elicit a secondary, de novo HIV-1–specific CD8+ T cell response with an alternative TCR repertoire in chronic infection. In addition to altering recognition by HIV-1–specific CD8+ T cells, the HLA-B2705–KK10 L6M complex also exhibits substantially increased binding to the immunoglobulin-like transcript (ILT) receptor 4, an inhibitory MHC class I–specific receptor expressed on myelomonocytic cells. Binding of the B2705–KK10 L6M complex to ILT4 leads to a tolerogenic phenotype of myelomonocytic cells with lower surface expression of dendritic cell (DC) maturation markers and co-stimulatory molecules. These data suggest a link between CTL-driven mutational escape, altered recognition by innate MHC class I receptors on myelomonocytic cells, and functional impairment of DCs, and thus provide important new insight into biological consequences of viral sequence diversificatio

Steplike electric conduction in a classical two-dimensional electron system through a narrow constriction in a microchannel

Using molecular dynamics simulation, we investigate transport properties of a classical two-dimensional electron system confined in a microchannel with a narrow constriction. As a function of the confinement strength of the constriction, the calculated conductance in the simulations exhibits steplike increases as reported in a recent experiment [D. G. Rees et al., Phys. Rev. Lett. 106, 026803 (2011)]. It is confirmed that the number of the steps corresponds to the number of stream lines of electrons through the constriction. We verify that density fluctuation plays a major role in smoothing the steps in the conductance.Comment: 11 pages, 9 figure

Field-induced structure transformation in electrorheological solids

We have computed the local electric field in a body-centered tetragonal (BCT) lattice of point dipoles via the Ewald-Kornfeld formulation, in an attempt to examine the effects of a structure transformation on the local field strength. For the ground state of an electrorheological solid of hard spheres, we identified a novel structure transformation from the BCT to the face-centered cubic (FCC) lattices by changing the uniaxial lattice constant c under the hard sphere constraint. In contrast to the previous results, the local field exhibits a non-monotonic transition from BCT to FCC. As c increases from the BCT ground state, the local field initially decreases rapidly towards the isotropic value at the body-centered cubic lattice, decreases further, reaching a minimum value and increases, passing through the isotropic value again at an intermediate lattice, reaches a maximum value and finally decreases to the FCC value. An experimental realization of the structure transformation is suggested. Moreover, the change in the local field can lead to a generalized Clausius-Mossotti equation for the BCT lattices.Comment: Submitted to Phys. Rev.

Vortex-antivortex wavefunction of a degenerate quantum gas

A mechanism of a pinning of the quantized matter wave vortices by optical vortices in a specially arranged optical dipole traps is discussed. The vortex-antivortex optical arrays of rectangular symmetry are shown to transfer angular orbital momentum and form the "antiferromagnet"-like matter waves. The separable Hamiltonian for matter waves in pancake trapping geometry is proposed and 3D-wavefunction is factorized in a product of wavefunctions of the 1D harmonic oscillator and 2D vortex-antivortex quantum state. The 2D wavefunction's phase gradient field associated via Madelung transform with the field of classical velocities forms labyrinth-like structure. The macroscopic quantum state composed of periodically spaced counter-rotating BEC superfluid vortices has zero angular momentum and nonzero rotational energy.Comment: 11 pages, 5 figure

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The impact of coherence on the nonlinear optical response and stationary transport is studied in quantum cascade laser structures. Nonequilibrium effects such as pump-probe signals, the spatio-temporally resolved electron density evolution, and the subband population dynamics (Rabi flopping) as well as the stationary current characteristics are investigated within a microscopic density-matrix approach. Focusing on the stationary current and the recently observed gain oscillations, it is found that the inclusion of coherence leads to observable coherent effects in opposite parameter regimes regarding the relation between the level broadening and the tunnel coupling across the main injection barrier. This shows that coherence plays a complementary role in stationary transport and nonlinear optical dynamics in the sense that it leads to measurable effects in opposite regimes. For this reason, a fully coherent consideration of such nonequilibrium structures is necessary to describe the combined optical and transport propertiesComment: 14 pages, 11 figures; final versio

3-D disks using photopolymer films

The recording characteristics of DuPont's HRF-150 photopolymer film are described. The application of these films for data storage using the 3-D holographic disk architecture is presented. The required system's bandwidth due to the photopolymer's limited thickness is shown to be the limiting factor of the storage capacity of these thin films and not the material's dynamic range. A new multiplexing method (peristrophic multiplexing) that significantly increases the film's capacity and changes the limiting factor from system bandwidth to material dynamic range is presented

Analytic Quantization of the QCD String

We perform an analytic semi-classical quantization of the straight QCD string with one end fixed and a massless quark on the other, in the limits of orbital and radial dominant motion. We compare our results to the exact numerical semi-classical quantization. We observe that the numerical semi-classical quantization agrees well with our exact numerical canonical quantization.Comment: RevTeX, 10 pages, 9 figure

Corotation: its influence on the chemical abundance pattern of the Galaxy

A simple theory for the chemical enrichment of the Galaxy which takes into account the effects of spiral arms on heavy elements output was developed. In the framework of the model with the corotation close to the position of the Sun in the Galaxy the observed abundance features are explained.Comment: LaTeX, 6 pages, 5 jpg figures, uses aastex.sty, submitted to ApJ Let