Unstable phase singularities in noise contaminated images

2020 ◽  
Author(s):  
Astrid Lorena Villamizar Amado ◽  
Nelly Cap ◽  
Silvana Gallo ◽  
Hector Rabal ◽  
Myrian Tebaldi
Keyword(s):  
Unstable Phase ◽  
Phase Singularities

scholarly journals Optically Unstable Phase from Ion-Ion Interactions in an Erbium-Doped Crystal

2021 ◽  
Vol 126 (11) ◽  
Author(s):  
Yu-Hui Chen ◽  
Sebastian P. Horvath ◽  
Jevon J. Longdell ◽  
Xiangdong Zhang
Keyword(s):  
Ion Interactions ◽  
Unstable Phase ◽  
Erbium Doped

scholarly journals Moiré pattern of interference dislocations in condensate of indirect excitons

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J. R. Leonard ◽  
Lunhui Hu ◽  
A. A. High ◽  
A. T. Hammack ◽  
Congjun Wu ◽  
...  
Keyword(s):  
Long Range ◽  
Direct Measurement ◽  
Quantum Systems ◽  
Matter Waves ◽  
Moire Pattern ◽  
Indirect Excitons ◽  
Moiré Pattern ◽  
Moiré Effect ◽  
Phase Singularities ◽  
Bose Einstein

AbstractInterference patterns provide direct measurement of coherent propagation of matter waves in quantum systems. Superfluidity in Bose–Einstein condensates of excitons can enable long-range ballistic exciton propagation and can lead to emerging long-scale interference patterns. Indirect excitons (IXs) are formed by electrons and holes in separated layers. The theory predicts that the reduced IX recombination enables IX superfluid propagation over macroscopic distances. Here, we present dislocation-like phase singularities in interference patterns produced by condensate of IXs. We analyze how exciton vortices and skyrmions should appear in the interference experiments and show that the observed interference dislocations are not associated with these phase defects. We show that the observed interference dislocations originate from the moiré effect in combined interference patterns of propagating condensate matter waves. The interference dislocations are formed by the IX matter waves ballistically propagating over macroscopic distances. The long-range ballistic IX propagation is the evidence for IX condensate superfluidity.

scholarly journals Wavefront dislocations reveal the topology of quasi-1D photonic insulators

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Clément Dutreix ◽  
Matthieu Bellec ◽  
Pierre Delplace ◽  
Fabrice Mortessagne
Keyword(s):  
Local Density ◽  
Topological Defects ◽  
Wave Functions ◽  
Topological Classification ◽  
Local Density Of States ◽  
Topological Phase Transition ◽  
Interference Fringes ◽  
Classical Wave ◽  
Phase Singularities

AbstractPhase singularities appear ubiquitously in wavefields, regardless of the wave equation. Such topological defects can lead to wavefront dislocations, as observed in a humongous number of classical wave experiments. Phase singularities of wave functions are also at the heart of the topological classification of the gapped phases of matter. Despite identical singular features, topological insulators and topological defects in waves remain two distinct fields. Realising 1D microwave insulators, we experimentally observe a wavefront dislocation – a 2D phase singularity – in the local density of states when the systems undergo a topological phase transition. We show theoretically that the change in the number of interference fringes at the transition reveals the topological index that characterises the band topology in the insulator.

Healing of Carotid Stents: A Prospective Duplex Ultrasound Study

2003 ◽  
Vol 10 (3) ◽  
pp. 636-642 ◽  
Author(s):  
Andrea Willfort-Ehringer ◽  
Ramazanali Ahmadi ◽  
Michael E. Gschwandtner ◽  
Angelika Haumer ◽  
Gottfried Heinz ◽  
...  
Keyword(s):  
Carotid Arteries ◽  
Duplex Ultrasound ◽  
Stable Phase ◽  
Carotid Stent ◽  
Time Intervals ◽  
Unstable Phase ◽  
Ultrasound Study ◽  
Maximal Thickness ◽  
Second Year

Purpose: To study the dynamics of carotid stent healing over a 2-year period using duplex ultrasound imaging. Methods: One hundred twelve patients with 121 successfully stented carotid arteries were examined with color-coded duplex ultrasound the day after the stent procedure and at 1, 3, 6, 12, and 24 months in follow-up. The maximal thickness and echogenicity of the layer between the stent and the perfused lumen (SPL) were evaluated. Echogenicity was classified as echogenic if the SPL layer was clearly detected in B mode and echolucent if the SPL layer was barely visible in B mode, its border defined by assistance of color-coded flow. Results: At day 1, an echolucent SPL layer with a median thickness of 0.7 mm was interpreted as a thrombotic layer, which decreased at 1 month to practically zero (i.e., not detectable). In follow-up, increases in thickness (mainly up to 6 months) and echogenicity (up to 12 months) of the SPL layer were interpreted as neointimal ingrowth. At 3, 6, and 12 months, the median maximal thickness of the SPL layer was 0.5 mm, 0.9 mm, and 1.0 mm, respectively, whereas the percentage of patients with an echogenic SPL layer was 27% (32/119), 56% (66/117), and 95% (105/110), respectively, at the same time intervals. No further change was observed at the 24-month examination. Conclusions: Three phases of carotid stent incorporation are defined: (1) an early unstable period soon after stent placement with an echolucent (thrombotic) SPL layer, (2) a moderately unstable phase with ingrowing neointima (1–12 months), and (3) a stable phase from the second year on. These data may indicate the need for different intensities of therapy and surveillance intervals.

Identification of superconducting phases in the Ba-Ca-Cu-O system: an unstable phase with Tc≈126 K and its derivative with Tc≈90 K

1999 ◽  
Vol 9 (5) ◽  
pp. 1141-1148 ◽  
Author(s):  
T. Hosomi ◽  
H. Suematsu ◽  
H. Fjellvåg ◽  
M. Karppinen ◽  
H. Yamauchi
Keyword(s):  
Superconducting Phases ◽  
Unstable Phase

scholarly journals The atomic process in ferromagnetic Induction

1922 ◽  
Vol 100 (706) ◽  
pp. 449-460 ◽  
Keyword(s):  
Magnetic Particles ◽  
Strong Field ◽  
Molecular Magnets ◽  
Magnetic Element ◽  
Atomic Process ◽  
Dissipation Of Energy ◽  
Unstable Phase ◽  
Complete Alignment ◽  
The Stability ◽  
Ferromagnetic Substance

The object of this paper is to amend, in an important particular, the theory of ferromagnetic induction put forward by me more than 30 years ago, and to describe a new model. That theory was itself a modification of the earlier theory of Weber. To Weber is due the fundamental notion that a substance contains minute particles, each of which acts as a magnet, and that in the process of magnetising a ferromagnetic substance these are turned into more or less complete alignment. The ultimate magnetic particles use to be called “molecular magnets”: we now recognise them as attributes of the atom, not of the molecule, and (in all probability) they derive their magnetic moment from the circulation of electricity in electron orbits or in ring electrons. What turns is not the molecule nor the atom, but something within the atom. The characteristics which distinguish ferromagnetic substances from other paramagnetics are: (1) the much larger amount of magnetism they can acquire under the action of an impressed field; (2) the fact that the acquired magnetism tends towards a saturation limit when the field is progressively increased; (3) the fact that the acquired magnetism shows hysteresis with respect to variations of the field, except in certain small initial changes. Weber’s theory explained (1) and (2). My modification of it explained, in addition, (3) as an effect of the irreversible action which occurs when the equilibrium of a magnetic element becomes unstable through change in the externally impressed magnetic force, and it swings over, with dissipation of energy, into a new position of stability. The stability in both positions is sufficiently explained by magnetic forces only. In breaking away from one stable position it is deflected at first in a quasi­-elastic (reversible) manner until the external force reaches a certain value at which the equilibrium is upset. The essence of hysteresis is the turning from one position of stability to another, through a region of instability. If the conditions are such that there is no unstable phase in the turning, then there is no dissipation of energy, and consequently no hysteresis. This occurs in very feeble magnetisation, when the deflections are reversible; it also occurs if the piece be caused to rotate in a field of great strength. J. Swinburne pointed out that, as a consequence of my theory, hysteresis should vanish when a cylinder of ferromagnetic metal is rotated in a very strong field, and this curious result was confirmed experimentally by F. G. Baily.

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