Wavelength-multiplexed duplex transceiver based on III-V/Si hybrid integration for off-chip and on-chip optical interconnects

A six-channel wavelength-division-multiplexed optical transceiver with a compact footprint of 1.5 x 0.65 mm(2) for off-chip and on-chip interconnects is demonstrated on a single silicon-on-insulator chip. An arrayed waveguide grating is used as the (de)multiplexer, and III-V electroabsorption sections fabricated by hybrid integration technology are used as both modulators and detectors, which also enable duplex links. The 30-Gb/s capacity for each of the six wavelength channels for the off-chip transceiver is demonstrated. For the on-chip interconnect, an electrical-to-electrical 3-dB bandwidth of 13 GHz and a data rate of 30 Gb/s per wavelength are achieved

High-strength steel wires containing corrosion pits : stress analysis and critical distance based fatigue life estimation

The present paper deals with the problem of assessing the fatigue lifetime of high-strength steel wires containing corrosion pits, with this investigation being based on a large number of experimental data selected from the technical literature. To evaluate the stress concentration phenomena characterising corroded metallic wires, according to the state-of-the-art knowledge, pits were modelled either as semi-ellipsoidal cavities or as hemispherical notches. The stress concentration factors, Kt, associated with these simplified pit geometries were calculated numerically by solving numerous three-dimensional FE models. Subsequently, the Kt values being determined according to this standard numerical procedure were post-processed systematically to derive simple analytical solutions suitable for estimating, in situations of engineering interest, the stress concentration factors associated with pitting corrosion. Finally, after making some assumptions to derive the necessary fatigue properties, the Theory of Critical Distances was used in the form of the Point Method and the Line Method to re-analyse the literature data being collected. This systematic validation exercise allowed us to prove that the Theory of Critical Distances is successful also in assessing the fatigue lifetime of high-strength metallic cables containing corrosion pits, with the obtained estimates falling within an error factor of 3. Therefore, as far as wires weakened by corrosion pits are concerned, it was demonstrated that the Theory of Critical Distances can be used to post-process the local linear-elastic stress fields when they are not only determined numerically, but also estimated by using those standard analytical solutions which are strictly valid solely for conventional notches

Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay

The decay channel $\psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p})$ is studied using a sample of $1.06\times 10^8$ $\psi^\prime$ events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the $p\bar{p}$ invariant mass spectrum. The enhancement can be fit with an $S$-wave Breit-Wigner resonance function with a resulting peak mass of $M=1861^{+6}_{-13} {\rm (stat)}^{+7}_{-26} {\rm (syst)} {\rm MeV/}c^2$ and a narrow width that is $\Gamma<38 {\rm MeV/}c^2$ at the 90% confidence level. These results are consistent with published BESII results. These mass and width values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics

The Werner Syndrome Helicase/Exonuclease Processes Mobile D-Loops through Branch Migration and Degradation

RecQ DNA helicases are critical for preserving genome integrity. Of the five RecQ family members identified in humans, only the Werner syndrome protein (WRN) possesses exonuclease activity. Loss of WRN causes the progeroid disorder Werner syndrome which is marked by cancer predisposition. Cellular evidence indicates that WRN disrupts potentially deleterious intermediates in homologous recombination (HR) that arise in genomic and telomeric regions during DNA replication and repair. Precisely how the WRN biochemical activities process these structures is unknown, especially since the DNA unwinding activity is poorly processive. We generated biologically relevant mobile D-loops which mimic the initial DNA strand invasion step in HR to investigate whether WRN biochemical activities can disrupt this joint molecule. We show that WRN helicase alone can promote branch migration through an 84 base pair duplex region to completely displace the invading strand from the D-loop. However, substrate processing is altered in the presence of the WRN exonuclease activity which degrades the invading strand both prior to and after release from the D-loop. Furthermore, telomeric D-loops are more refractory to disruption by WRN, which has implications for tighter regulation of D-loop processing at telomeres. Finally, we show that WRN can recognize and initiate branch migration from both the 5′ and 3′ ends of the invading strand in the D-loops. These findings led us to propose a novel model for WRN D-loop disruption. Our biochemical results offer an explanation for the cellular studies that indicate both WRN activities function in processing HR intermediates

Experience-based behavioral and chemosensory changes in the generalist insect herbivore Helicoverpa armigera exposed to two deterrent plant chemicals

Behavioral and electrophysiological responses of larvae of the polyphagous moth species Helicoverpa armigera to two plant-derived allelochemicals were studied, both in larvae that had been reared on a diet devoid of these compounds and in larvae previously exposed to these compounds. In dual-choice cotton leaf disk and pepper fruit disk arena assays, caterpillars reared on a normal artificial diet were strongly deterred by strychnine and strophanthin-K. However, caterpillars reared on an artificial diet containing strychnine were insensitive to strychnine and strophanthin-K. Similarly, caterpillars reared on an artificial diet containing strophanthin-K were also desensitized to both deterrent chemicals. Electrophysiological tests revealed that the deterrent-sensitive neurons in taste sensilla on the maxillae of caterpillars reared on each deterrent-containing diet displayed reduced sensitivity to the two chemicals compared with the caterpillars reared on normal diets. We conclude that the experience-dependent behavioral plasticity was partly based on the reduced sensitivity of taste receptor neurons and that the desensitization of taste receptor neurons contributed to the cross-habituation to the two chemicals

miR-198 Inhibits HIV-1 Gene Expression and Replication in Monocytes and Its Mechanism of Action Appears To Involve Repression of Cyclin T1

Cyclin T1 is a regulatory subunit of a general RNA polymerase II elongation factor known as P-TEFb. Cyclin T1 is also required for Tat transactivation of HIV-1 LTR-directed gene expression. Translation of Cyclin T1 mRNA has been shown to be repressed in human monocytes, and this repression is relieved when cells differentiate to macrophages. We identified miR-198 as a microRNA (miRNA) that is strongly down-regulated when monocytes are induced to differentiate. Ectopic expression of miR-198 in tissue culture cells reduced Cyclin T1 protein expression, and plasmid reporter assays verified miR-198 target sequences in the 3′ untranslated region (3′UTR) of Cyclin T1 mRNA. Cyclin T1 protein levels increased when an inhibitor of miR-198 was transfected into primary monocytes, and overexpression of miR-198 in primary monocytes repressed the normal up-regulation of Cyclin T1 during differentiation. Expression of an HIV-1 proviral plasmid and HIV-1 replication were repressed in a monocytic cell line upon overexpression of miR-198. Our data indicate that miR-198 functions to restrict HIV-1 replication in monocytes, and its mechanism of action appears to involve repression of Cyclin T1 expression

Nicotine exposure and transgenerational impact: a prospective study on small regulatory microRNAs

Early developmental stages are highly sensitive to stress and it has been reported that pre-conditioning with tobacco smoking during adolescence predisposes those youngsters to become smokers as adults. However, the molecular mechanisms of nicotine-induced transgenerational consequences are unknown. In this study, we genome-widely investigated the impact of nicotine exposure on small regulatory microRNAs (miRNAs) and its implication on health disorders at a transgenerational aspect. Our results demonstrate that nicotine exposure, even at the low dose, affected the global expression profiles of miRNAs not only in the treated worms (F0 parent generation) but also in two subsequent generations (F1 and F2, children and grandchildren). Some miRNAs were commonly affected by nicotine across two or more generations while others were specific to one. The general miRNA patterns followed a “two-hit� model as a function of nicotine exposure and abstinence. Target prediction and pathway enrichment analyses showed daf-4, daf-1, fos-1, cmk-1, and unc-30 to be potential effectors of nicotine addiction. These genes are involved in physiological states and phenotypes that paralleled previously published nicotine induced behavior. Our study offered new insights and further awareness on the transgenerational effects of nicotine exposed during the vulnerable post-embryonic stages, and identified new biomarkers for nicotine addiction.ECU Open Access Publishing Support Fun

Removal of AU Bias from Microarray mRNA Expression Data Enhances Computational Identification of Active MicroRNAs

Elucidation of regulatory roles played by microRNAs (miRs) in various biological networks is one of the greatest challenges of present molecular and computational biology. The integrated analysis of gene expression data and 3′-UTR sequences holds great promise for being an effective means to systematically delineate active miRs in different biological processes. Applying such an integrated analysis, we uncovered a striking relationship between 3′-UTR AU content and gene response in numerous microarray datasets. We show that this relationship is secondary to a general bias that links gene response and probe AU content and reflects the fact that in the majority of current arrays probes are selected from target transcript 3′-UTRs. Therefore, removal of this bias, which is in order in any analysis of microarray datasets, is of crucial importance when integrating expression data and 3′-UTR sequences to identify regulatory elements embedded in this region. We developed visualization and normalization schemes for the detection and removal of such AU biases and demonstrate that their application to microarray data significantly enhances the computational identification of active miRs. Our results substantiate that, after removal of AU biases, mRNA expression profiles contain ample information which allows in silico detection of miRs that are active in physiological conditions