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Fresnel diffraction due to phase gradient singularity
Optics Letters, 2018In this Letter, a singularity in the phase gradient is introduced as a new origin of the diffraction from phase objects. The continuity in the amplitude and phase of the wave and the singularity in the phase gradient are assumed to describe this phenomenon.
Ehsan A. Akhlaghi +2 more
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Phase separation under a weak concentration gradient
Physical Review Letters, 1992Phase separation dynamics is studied in a density-matched liquid mixture in the presence of a weak linear concentration gradient. This novel situation enables nucleation and spinodal decomposition to be studied simultaneously. We observe at all quench depths (i) a central zone of nearly constant concentration width where interconnected domains grow ...
, Jayalakshmi, , Khalil, , Beysens
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Phase behavior of gradient copolymers
AIP Conference Proceedings, 2000Phase properties of gradient AB copolymer melts which consist of chains with the specified chemical distribution of A and B monomers have been studied within the Landau-Ginzburg model. All the melts with the linear distribution of the monomers exhibit only a direct continuous phase transition from disordered to the lamellar phase.
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Phase Transition as a Gradient Amplifier
Science's STKE, 2005Chemotactic cells can detect and move toward a shallow gradient of chemoattractant. This directional movement involves the localized synthesis of membrane lipids, specifically phosphatidylinositol 3,4,5-trisphosphate (PIP 3 ), which is formed in response to recruitment of phosphoinositide 3-kinase (PI3K) at the site
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Peak compression in reversed-phase gradient elution
Journal of Chromatography A, 2006Previous reports suggest that peak widths in linear gradient elution are consistently larger than predicted by theory; however, if gradient compression is ignored, experiment and theory are in reasonable agreement. This suggests that gradient compression might represent an incorrect or poorly understood concept.
Uwe D, Neue +2 more
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Phase-gradient–based initialization for lensless quantitative phase imaging
Optics LettersQuantitative phase imaging of transparent samples with large phase variations is fundamentally challenged by the nonconvex nature of phase retrieval from intensity-only measurements. In this regime, conventional algorithms with random initialization often converge to nonphysical solutions and fail to recover meaningful phase information, even when the ...
Huazheng Wu +8 more
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Generalized Gradient Theory for Silica Phase Transitions
Physical Review Letters, 1996Density functional theory based on the generalized gradient approximation to the exchange and correlation energy is shown to correct a qualitative error of the local density approximation in describing a high-pressure phase transition of ${\mathrm{SiO}}_{2}$.
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Phase Retrieval via Accelerated Gradient Descent
2019Phase retrieval, as a non-convex optimization problem arises in many areas of signal processing, is to recover the missed signal phase. Based on the Truncated Wirtinger Flow (TWF), where the updating can be regarded as stochastic gradient descent, we present the Accelerated Wirtinger Flow (AWF), which updates the iterative process with accelerated ...
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Development and Progress in Acoustic Phase-Gradient Metamaterials for Wavefront Modulation
Materials Today, 2023Jingwen Guo, Renhao Qu
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