First-order PMD monitoring for NRZ data using RF clock regeneration techniques

We propose and demonstrate two novel techniques for 10 Gb/s polarization-mode-dispersion (PMD) monitoring for NRZ signals that use a regenerated RF clock tone as a monitoring signal. Our techniques regenerate the RF clock tone that is usually absent after square-law detection in the electrical NRZ data spectrum (in the absence of dispersion). Our first technique uses a dispersive element in the monitoring tap-line to put the beat terms between the optical clock sidebands and the carrier in phase and thus regenerates the RF clock tone after detection. Our second technique involves the use of an optical filter that is centered at the bit rate frequency on either the upper or lower sideband of the optical spectrum, removing one of the sidebands and thus preventing the beating that normally cancels the RF clock tone. We show (theoretically, via simulation, and experimentally) the effect that PMD has on these regenerated RF clock tones. We also demonstrate PMD compensation at 10 Gb/s using these techniques for monitoring and show a 6-dB improvement in the 1% power penalty tail. Our techniques are simple, do not require modification at the transmitter, and can be applied to WDM systems via the use of a multichannel dispersive element or a tunable filter swept across all channels.     

1.2 Gb/s closely-spaced FDMA-FSK direct-detection star network

For the frequency-division-multiple-access-frequency-shift-keying (FDMA-FSK) network, the FSK signal is converted to amplitude-shift-keyed (ASK) format by a tunable fiber Fabry-Perot (FFP) filter that acts simultaneously as a demodulator and demultiplexer. Frequency-tunable two-electrode distributed-feedback (DFB) laser transmitters produce distorted FSK spectra due to nonuniform FM response for modulation frequencies above ~200 Mb/s. The frequency-domain properties of the laser are related directly to the time-domain properties of the transmitted data stream. The critical dependence on the FFP passband width and center frequency location for undistorted signal recovery is shown. By optimizing these parameters, the data transmission rate can be increased while keeping the power penalty due to signal distortion below 1 dB     

The Application of Stimuli‐Responsive VEGF‐ and ATP‐Aptamer‐Based Microcapsules for the Controlled Release of an Anticancer Drug,and the Selective Targeted Cytotoxicity toward Cancer Cells

The synthesis of microcapsules consisting of DNA shells crosslinked by anti‐VEGF (vascular epithelial growth factor) or anti‐ATP (adenosine triphosphate) aptamers and loaded with tetramethylrhodamine‐modified dextran, TMR‐D, and Texas Red‐modified dextran, TR‐D, respectively, as fluorescence labels acting as models for drug loads, is described. The aptamer‐functionalized microcapsules act as stimuli‐responsive carriers for the triggered release of the fluorescent labels in the presence of the overexpressed cancer cell biomarkers VEGF or ATP. The VEGF‐ and ATP‐responsive microcapsules are, also, loaded with the anticancer drug doxorubicin (DOX), in the form of DOX‐functionalized dextran, DOX‐D. The release of DOX‐D from the respective microcapsules proceeds in the presence of VEGF or ATP as triggers. Preliminary cell experiments reveal that the ATP‐responsive DOX‐D‐loaded microcapsules undergo effective endocytosis into MDA‐MB‐231 cancer cells. The ATP‐responsive DOX‐D‐loaded microcapsules incorporated into the MDA‐MB‐231 cancer cells reveal impressive cytotoxicity as compared to normal epithelial MCF‐10A breast cells (50% vs 0% cell death after 24 h, respectively). The cytotoxicity of the ATP‐responsive DOX‐D‐loaded microcapsules toward the cancer cells is attributed to the effective unlocking of the microcapsules by overexpressed ATP, and to the subsequent release of DOX from the dextran backbone under acidic conditions present in cancer cells (pH = 6.2).     

Solar Cells with Enhanced Photocurrent Efficiencies Using Oligoaniline‐Crosslinked Au/CdS Nanoparticles Arrays on Electrodes

Different configurations of CdS nanoparticles (NPs) are linked to Au electrodes by electropolymerization of thioaniline‐functionalized CdS NPs onto thioaniline‐functionalized Au‐electrodes. In one configuration, thioaniline‐functionalized CdS NPs are electropolymerized in the presence of thioanline‐modified Au NPs to yield an oligoaniline‐crosslinked CdS/Au NPs array. The NP‐functionalized electrode generates a photocurrent with a quantum yield that corresponds to ca. 9%. The photocurrent intensities are controlled by the potential applied on the electrode, and the redox‐state of the oligoaniline bridge. In the oxidized quinoide state of the oligoaniline units, the bridges act as electron acceptors that trap the conduction‐band electrons that are transported to the electrode and lead to high quantum yield photocurrents. The reduced π‐donor oligoaniline bridges act as π‐donor sites that associate N,N′‐dimethyl‐4,4′‐bipyridinium, MV²⁺, by donor/acceptor interactions, K_a = 5270 M^?1. The associated MV²⁺ acts as an effective trap of the conduction‐band electrons, and in the presence of triethanolamine (TEOA) as an electron donor, high photocurrent values are measured (ca. 12% quantum yield). The electropolymerization of thioaniline‐functionalized Au NPs and thioaniline‐modified CdS NPs in the presence of MV²⁺ yields a MV²⁺‐imprinted NP array. The imprinted array exhibits enhanced affinities toward the association of MV²⁺ to the oligoaniline π‐donor sites, K_a = 2.29 × 10⁴ M^?1. This results in the effective trapping of the conduction‐band electrons and an enhanced quantum yield of the photocurrent, ca. 34%. The sacrificial electron donor, TEOA, was substituted with the reversible donor I₃^?. A solar cell consisting of the imprinted CdS/Au NPs array, with MV²⁺ and I₃^?, was constructed. The cell generated a photocurrent with a quantum yield of 4.7%.     

Optical Signal Processing Using Tunable Delay Elements Based on Slow Light

Tunable optical delay lines have many applications for high-performance optical switching and signal processing. Slow light has emerged as an enabling technology for achieving continuously tunable optical delays. Delay reconfigurability opens up a whole new field of nonlinear signal processing using slow light. In this paper, the authors review recent advances in slow-light-based optical signal processing, with a focus on the data fidelity after traversing the slow light elements. The concept of slow-light-induced data pattern dependence is introduced and is shown to be the main signal degrading effect. We then propose and experimentally demonstrate phase-preserving slow light by delaying 10 Gb/s differential phase-shift keying (DPSK) signals with reduced DPSK pattern dependence. Spectrally efficient slow light using advanced multilevel phase-modulated formats is further described. With this technique, doubled bit-rate signals can be transmitted through a bandwidth-limited slow light element. We finally show several novel slow-light-based signal processing modules. Unique features such as multichannel operation, variable bit-rate capability, and simultaneous multiple functions are highlighted.     

N-methyl-D-aspartate antagonist D-APV selectively disrupts taste-potentiated odor aversion learning.

Examined in 2 experiments the effects of the competitive N-methyl-{d}-aspartate (NMDA) antagonist {d}-APV ({d}-2-amino-5-phosphonovalerate) on rats' ability to acquire potentiated aversions to the odor element of a taste–odor compound. In Exp 1, pretreatment with {d}-APV (2.5 μg/side icv) caused stereospecific deficits in potentiated odor aversion learning but left simple taste and odor aversion learning intact. In Exp 2, pretreatment with {d}-APV had no effect on rats' acquisition of an illness-based odor discrimination task. These results parallel those previously obtained using a noncompetitive NMDA antagonist (G. S. Robinson et al, 1989) and show that interference with NMDA receptors can selectively impair potentiated odor aversion learning. These results suggest that NMDA receptors play a critical role in some, but not all, forms of learning and memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

600 mu m/min laser-induced nonthermal etching of GaAs in an HF solution

600 mu m/min room-temperature photochemical aqueous etching of n-type GaAs in an HF acid based solution is reported. This rapid etch rate is achieved under UV illumination and represents more than an order of magnitude enhancement over previously reported results for solutions containing no Hf acid. The process is used to fabricated deep large-area structures such as trench formations and through-wafer via holes which would otherwise be impractical with slower direct-write techniques.<>     

Screening for idiopathic scoliosis. Comparison of 90 cases shows less surgery by early diagnosis

Cutis marmorata telangiectatica congenita (CMTC), a rare benign condition usually present at birth, is characterized by areas of cutaneous marbling that often become more pronounced with low temperatures. The skin lesions typically become less prominent with age, but may be associated with a variety of abnormalities. Reported are three patients with vivid cutis marmorata who had leg length discrepancies (LLD) which, unlike most limb discrepancies caused by vascular malformations, involved relative growth retardation of the affected leg.     

Tunable wavelength spacing multi-wavelength ring laser using programmable DGD module as intra-cavity filter

A multi-wavelength fibre laser whose channel spacing can be dynamically and continuously tuned is demonstrated experimentally. A novel programmable magneto-optic-based DGD module is used as the intra-cavity optical filter to control the wavelength spacing. Channel spacing tunable from 0.4 to 1.6 nm is achieved.