Suppression of Rayleigh-scattering-induced noise in OEOs.

Optoelectronic oscillators (OEOs) are hybrid RF-photonic devices that promise to be environmentally robust high-frequency RF sources with very low phase noise. Previously, we showed that Rayleigh-scattering-induced noise in optical fibers coupled with amplitude-to-phase noise conversion in photodetectors and amplifiers leads to fiber-length-dependent noise in OEOs. In this work, we report on two methods for the suppression of this fiber-length-dependent noise: altering the amplitude-dependent phase delay of the OEO loops and suppressing the Rayleigh-scattering-induced noise in optical fibers.

Spontaneous inelastic Rayleigh scattering in optical fibers.

Rayleigh scattering (RS) adds noise to signals that are transmitted over optical fibers and other optical waveguides. This noise can be the dominant noise source in a range between 10 Hz and 100 kHz from the carrier and can seriously degrade the performance of optical systems that require low close-in noise. Using heterodyne techniques, we demonstrate that the backscattered close-in noise spectrum in optical fibers is symmetric about the carrier and grows linearly with both input power and fiber length.

Side-hole fiber sensor based on surface plasmon resonance.

Surface plasmon resonance (SPR) is demonstrated in a microstructured optical fiber sensor for the first time (to our knowledge). SPR features were observed at 560 and 620 nm when sample fluids of refractive indices n=1.38 and n=1.

Acute medical management of the non-ST-segment elevation acute coronary syndromes (NSTE-ACS) in older patients.

Older patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) represent many clinical challenges. For example diagnosis can be difficult, and comorbidities are common. Furthermore, NSTE-ACS is particularly common in older patients (>60% of acute myocardial infarctions occurring in patients aged 65 years or older) and the mortality associated with NSTE-ACS is particularly high.

Antiresonant reflection and inhibited coupling in hollow-core square lattice optical fibres.

We propose a guidance mechanism in hollow-core optical fibres dominated by antiresonant reflection from struts of solid material in the cladding. Resonances with these struts determine the high loss bands of the fibres, and vector effects become important in determining the width of these bands through the non-degeneracy of the TE and TM polarised strut modes near cut-off. Away from resonances the light is confined through the inhibited coupling mechanism.

Collision-induced timing shifts in dispersion-managed soliton systems.

The frequency and timing shifts associated with dispersion-managed solitons in a wavelength-division multiplexed system are computed by the numerically efficient Poisson sum technique. Analytical formulas are attainable by use of this approach with a Gaussian approximation for the soliton. The results are favorably compared with known results for the frequency shift.

Asymptotic analysis of collision-induced timing shifts in return-to-zero quasi-linear systems with predispersion and postdispersion compensation.

An asymptotic method for calculating the collision-induced frequency and timing shifts for quasi-linear pulses in return-to-zero, wavelength-division multiplexed systems with predispersion and postdispersion compensation is developed. Predictions of the asymptotic theory agree well with quadrature and direct numerical simulations. Using this theory, computational savings of many orders of magnitude can be realized over direct numerical simulations.

Dissecting the role of matrix metalloproteinases (MMP) and integrin alpha(v)beta3 in angiogenesis in vitro: absence of hemopexin C domain bioactivity, but membrane-Type 1-MMP and alpha(v)beta3 are critical.

Matrix metalloproteinase (MMP)-2 and its hemopexin C domain autolytic fragment (also called PEX) have been proposed to be crucial for angiogenesis. Here, we have investigated the dependency of in vitro angiogenesis on MMP-mediated extracellular proteolysis and integrin alpha(v)beta3-mediated cell adhesion in a three-dimensional collagen I model. The hydroxamate-based synthetic inhibitors BB94, CT1399, and CT1847 inhibited endothelial cell invasion, as did neutralizing anti-membrane-type 1-MMP (MT1-MMP) antibodies and tissue inhibitor of MMP (TIMP)-2 and TIMP-3 but not TIMP-1.

Calculation, characterization, and application of the time shift function in wavelength-division-multiplexed return-to-zero systems.

We calculate the time shift function for collisions of pairs of pulses in different channels in a prototypical return-to-zero wavelength-division-multiplexed system with dispersion management and precompensation and postcompensation. Once the time shift function is known, the impairments that are due to collision-induced timing jitter can be rapidly determined. We characterize the shape of this function and determine how it scales with the initial pulse separation in time and with channel separation in wavelength.

Reduction of collision-induced timing shifts in dispersion-managed quasi-linear systems with periodic-group-delay dispersion compensation.

Periodic-group-delay (PGD) dispersion-compensation modules were recently proposed as mechanisms to alleviate collision-induced timing shifts in dispersion-managed (DM) systems. Frequency and timing shifts in quasi-linear DM systems with PGDs were obtained, and it is shown that significant reductions are achieved when even a small fraction of the total dispersion is compensated for by PGDs.

Incomplete collisions in strongly dispersion-managed return-to-zero communication systems.

Incomplete collisions in wavelength-division-multiplexed return-to-zero transmission systems are analyzed by asymptotic methods. Formulas for frequency and timing shifts are obtained. The results agree with direct numerical calculations.

Treatment of hypertensive patients with coexisting coronary arterial disease.

Despite clear guidelines and an array of available antihypertensive medications, patients with hypertension and coronary artery disease are often inadequately treated. New data from HOPE, LIFE, and ALLHAT underscores the importance of blood pressure reduction for patients with coronary artery disease. Despite our improved understanding of the mechanism by which the various classes of antihypertensive medications achieve their effect, it remains the case that blood pressure reduction remains more important than the medication used to achieve the reduction.

Pulmonary hypertension secondary to left ventricular dysfunction: the role of nitric oxide and endothelin-1 in the control of pulmonary vascular tone.

1. Using an in vivo model of pulmonary hypertension (PHT) secondary to left ventricular dysfunction (LVD), the pulmonary arterial response to the nitric oxide synthase (NOS) blocker L-NAME (30 micromol.min(-1) i.