753 research outputs found
Approximate solutions and scaling transformations for quadratic solitons
We study quadratic solitons supported by two- and three-wave parametric
interactions in chi-2 nonlinear media. Both planar and two-dimensional cases
are considered. We obtain very accurate, 'almost exact', explicit analytical
solutions, matching the actual bright soliton profiles, with the help of a
specially-developed approach, based on analysis of the scaling properties.
Additionally, we use these approximations to describe the linear tails of
solitary waves which are related to the properties of the soliton bound states.Comment: 11 pages, 9 figures; submitted for publicatio
Solitary-wave vortices in quadratic nonlinear media
We find families of vortex solitary waves in bulk quadratic nonlinear media under conditions for second-harmonic generation. We show that the vortex solitary waves are azimuthally unstable and that they decay into sets of stable spatial solitons. We calculate the growth rates of the azimuthal perturbations and show how those affect the pattern of output light.
© 1998 Optical Society of AmericaPeer ReviewedPostprint (published version
Sex Differential in 15-Hydroxyprostaglandin Dehydrogenase Levels in the Lumen of Human Intracranial Aneurysms.
BACKGROUND: Aspirin is a promising medical therapy for the prevention of intracranial aneurysm (IA) rupture. Recently, we found that men have a better response to aspirin than women. The purpose of this study was to determine whether a sex differential exists in the level of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in the lumen of human IAs.
METHODS AND RESULTS: Consecutive patients undergoing coiling or stent-assisted coiling for a saccular IA at our institution were enrolled. Two samples (A and B) were collected from IA lumens, and the plasma level of 15-PGDH was measured using an ELISA-based method. The study included 38 patients, with 20 women and 18 men. Women and men were comparable on baseline characteristics. The mean plasma concentration of 15-PGDH did not differ statistically between sample A (62.8±16.2 ng/mL) and sample B (61.8±17.9 ng/mL; 95% confidence interval -6.6 to 9.4). The mean plasma concentration of 15-PGDH in IA lumens of samples A and B was significantly higher in men (73.8±13.5 ng/mL) than women (49.6±7.8 ng/mL; P\u3c0.0001).
CONCLUSIONS: Higher enzyme levels of 15-PGDH exist in the lumen of IAs of men compared with women. This observation could explain why aspirin confers better protection against IA rupture in men than in women. The susceptibility of an individual to aspirin may differ according to the level of 15-PGDH
Enhanced soliton interactions by inhomogeneous nonlocality and nonlinearity
We address the interactions between optical solitons in the system with
longitudinally varying nonlocality degree and nonlinearity strength. We
consider a physical model describing light propagation in nematic liquid
crystals featuring a strongly nonlocal nonlinear response. We reveal that the
variation of the nonlocality and nonlinearity along the propagation direction
can substantially enhance or weaken the interaction between out-of-phase
solitons. This phenomenon manifests itself as a slowdown or acceleration of the
soliton collision dynamics in one-dimensional geometries or of the soliton
spiraling rate in bulk media. Therefore, one finds that by engineering the
nonlocality and nonlinearity variation rate one can control the output soliton
location.Comment: 22 pages, 5 figures, to appear in Physical Review
Topological dragging of solitons
We put forward properties of solitons supported by optical lattices featuring
topological dislocations, and show that solitons experience attractive and
repulsive forces around the dislocations. Suitable arrangements of dislocations
are even found to form soliton traps, and the properties of such solitons are
shown to crucially depend on the trap topology. The uncovered phenomenon opens
a new concept for soliton control and manipulation, e.g., in disk-shaped
Bose-Einstein condensates.Comment: 15 pages, 5 figures, to appear in Physical Review Letter
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