Frequency stabilization and noise-induced spectral narrowing in resonators with zero dispersion.

Mechanical resonators are widely used as precision clocks and sensitive detectors that rely on the stability of their eigenfrequencies. The phase noise is determined by different factors including thermal noise, frequency noise of the resonator and noise in the feedback circuitry. Increasing the vibration amplitude can mitigate some of these effects but the improvements are limited by nonlinearities that are particularly strong for miniaturized micro- and nano-mechanical systems.

Aqueous humor glycation marker and plasma homocysteine in macular degeneration.

Background: We investigated concentrations of total homocysteine (tHcy) in elderly people without and those with age-related macular degeneration (AMD). In addition, we tested the association between plasma tHcy and one glycation marker in aqueous humor.

Methods: People with cataract only (n=48), patients with dry AMD (n=38) and those with wet AMD (n=31) were studied.

Results of excimer laser penetrating keratoplasty in aphakic eyes.

Background: Corneal grafting in aphakic eyes is often challenging. We report about the outcome of excimer laser trephination in aphakic eyes.

Methods: We examined 17 eyes of 17 patients.

Wilson ratio of a Tomonaga-Luttinger liquid in a spin-1/2 Heisenberg ladder.

Using micromechanical force magnetometry, we have measured the magnetization of the strong-leg spin-1/2 ladder compound (C(7)H(10)N)(2)CuBr(2) at temperatures down to 45 mK. Low-temperature magnetic susceptibility as a function of field exhibits a maximum near the critical field H(c) at which the magnon gap vanishes, as expected for a gapped one-dimensional antiferromagnet. Above H(c) a clear minimum appears in the magnetization as a function of temperature, as predicted by theory.

[Acute unilateral loss of vision in a 38-year-old male patient].

Although Valsalva retinopathy is a rare condition, it should be considered in the differential diagnosis of an acute macular hemorrhage in an otherwise healthy young patient. In most cases the patient presents with sudden, painless visual deterioration and a central scotoma. It is essential to immediately acquire a medical history because patients have typically undertaken strenuous physical activity in the recent past.

[Glaucoma with primary iris malformations. Axenfeld-Rieger syndromes, ICE syndromes (essential iris atrophy, Chandler's syndrome, Cogan-Reese syndrome), aniridia].

Iris malformations are often associated with malformations of the entire eye and systemic diseases. Malformations of the anterior chamber angle can lead to juvenile glaucoma. Axenfeld-Rieger syndromes have autosomal dominant transmission and are associated with juvenile glaucoma in 50-60% of patients.