1,645 research outputs found
Effects of prostaglandin analog therapy on the ocular surface of glaucoma patients
Michael B Horsley, Malik Y KahookRocky Mountain Lions Eye Institute, Department of Ophthalmology, University of Colorado Denver, Aurora, CO, USAPurpose: To quantify changes in tear break-up time (TBUT), corneal staining and ocular surface disease index (OSDI) in glaucoma patients after switching therapy from latanoprost with 0.02% benzalkonium chloride (BAK) to travoprost with sofZia™.Methods: Prospective consecutive case series evaluating patients before and 8 weeks after switching from latanoprost with BAK to travoprost with sofZia™ in patients with baseline TBUT less than 6 seconds.Results: Forty eyes of 20 consecutive patients using latanoprost with BAK were switched to travoprost with sofZia™. Mean TBUT prior to starting travoprost was 2.02 ± 0.71 seconds and increased to 6.34 ± 1.31 seconds 8 weeks after the switch (p < 0.001). Mean inferior corneal staining scores decreased from 2.40 ± 0.87 to 1.38 ± 0.59 (p < 0.001). Mean OSDI scores decreased from 26.31 ± 8.25 to 16.56 ± 6.19 (p < 0.001).Discussion: This report focuses on the status of the ocular surface, as documented by TBUT, corneal staining and OSDI, in patients switched from latanoprost with BAK to travoprost without BAK. The switch resulted in a statistically significant increase in TBUT and decreases in corneal staining and OSDI in patients with low baseline TBUT values.Conclusion: BAK, a common preservative for glaucoma drops, may increase OSD by disrupting the tear film and increasing conjunctival inflammation. In this study, a change from a BAK-preserved prostaglandin analog (PGA) to a non-BAK-preserved PGA resulted in a measurable improvement of TBUT, corneal staining and OSDI. Further studies are needed to better understand the impact of BAK-preserved medications on the ocular surface.Keywords: ocular surface, glaucoma, benzalkonium chloride, prostaglandin analo
Time varying gratings model Hawking radiation
Diffraction gratings synthetically moving at trans-luminal velocities contain
points where wave and grating velocities are equal. We show these points can be
understood as a series of optical event horizons where wave energy can be
trapped and amplified, leading to radiation from the quantum vacuum state. We
calculate the spectrum of this emitted radiation, finding a quasi-thermal
spectrum with features that depend on the grating profile, and an effective
temperature that scales exponentially with the length of the grating, emitting
a measurable flux even for very small grating contrast.Comment: 13 pages, 4 figure
A lattice evaluation of four-quark operators in the nucleon
Nucleon matrix elements of various four-quark operators are evaluated in
quenched lattice QCD using Wilson fermions. Some of these operators give rise
to twist-four contributions to nucleon structure functions. Furthermore, they
bear valuable information about the diquark structure of the nucleon. Mixing
with lower-dimensional operators is avoided by considering appropriate
representations of the flavour group. We find that for a certain flavour
combination of baryon structure functions, twist-four contributions are very
small. This suggests that twist-four effects for the nucleon might be much
smaller than m_p^2/Q^2.Comment: 17 pages, 3 figure
Applied lattice gauge calculations: diquark content of the nucleon
As an example of an application of lattice QCD we describe a computation of
four-quark operators in the nucleon. The results are interpreted in a diquark
language.Comment: 6 pages, 1 figure, Invited talk given by M. G\"ockeler at the
European Workshop on the QCD Structure of the Nucleon (QCD - N'02), Ferrara,
Italy, 3-6 Apr 200
High-dimensional spatial mode sorting and optical circuit design using multi-plane light conversion
Multi-plane light converters (MPLCs) are an emerging class of optical device
capable of converting a set of input spatial light modes to a new target set of
output modes. This operation represents a linear optical transformation - a
much sought after capability in photonics. MPLCs have potential applications in
both the classical and quantum optics domains, in fields ranging from optical
communications, to optical computing and imaging. They consist of a series of
diffractive optical elements (the 'planes'), typically separated by free-space.
The phase delays imparted by each plane are determined by the process of
inverse-design, most often using an adjoint algorithm known as the wavefront
matching method (WMM), which optimises the correlation between the target and
actual MPLC outputs. In this work we investigate high mode capacity MPLCs to
create arbitrary spatial mode sorters and linear optical circuits. We focus on
designs possessing low numbers of phase planes to render these MPLCs
experimentally feasible. To best control light in this scenario, we develop a
new inverse-design algorithm, based on gradient ascent with a specifically
tailored objective function, and show how in the low-plane limit it converges
to MPLC designs with substantially lower modal cross-talk and higher fidelity
than achievable using the WMM. We experimentally demonstrate several prototype
few-plane high-dimensional spatial mode sorters, operating on up to 55 modes,
capable of sorting photons based on their Zernike mode, orbital angular
momentum state, or an arbitrarily randomized spatial mode basis. We discuss the
advantages and drawbacks of these proof-of-principle prototypes, and describe
future improvements. Our work points to a bright future for high-dimensional
MPLC-based technologies
A class of invisible inhomogeneous media and the control of electromagnetic waves
We propose a general method to arbitrarily manipulate an electromagnetic wave
propagating in a two-dimensional medium, without introducing any scattering.
This leads to a whole class of isotropic spatially varying permittivity and
permeability profiles that are invisible while shaping the field magnitude
and/or phase. In addition, we propose a metamaterial structure working in the
infrared that demonstrates deep sub-wavelength control of the electric field
amplitude and strong reduction of the scattering. This work offers an
alternative strategy to achieve invisibility with isotropic materials and paves
the way for tailoring the propagation of light at the nanoscal
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