光纤专用网中基于DSP的Q值在线检测模块的设计

基于误码率与Q值的对应关系，本文介绍一种Q值在线检测方法，模块设计采用DSP技术，并讨论了该模块在光纤工业专用网（FIN）中的应用。     

Spatial learning deficits in mice with a targeted glucocorticoid receptor gene disruption

Previous studies in rats using the Morris water maze suggested that the processing of spatial information is modulated by corticosteroid hormones through mineralocorticoid and glucocorticoid receptors in the hippocampus. Mineralocorticoid receptors appear to be involved in the modulation of explorative behaviour, while additional activation of glucocorticoid receptors facilitates the storage of information. In the present study we used the water maze task to examine spatial learning and memory in mice homozygous and heterozygous for a targeted disruption of the glucocorticoid receptor gene. Compared with wild-type controls, homozygous and heterozygous mice were impaired in the processing of spatial but not visual information. Homozygous mutants performed variably during training, without specific platform-directed search strategies. The spatial learning disability was partly compensated for by increased motor activity. The deficits were indicative of a dysfunction of glucocorticoid receptors as well as of mineralocorticoid receptors. Although the heterozygous mice performed similarly to wild-type mice with respect to latency to find the platform, their strategy was more similar to that of the homozygous mice. Glucocorticoid receptor-related long-term spatial memory was impaired. The increased behavioural reactivity of the heterozygous mice in the open field points to a more prominent mineralocorticoid receptor-mediated function. The findings indicate that (i) the glucocorticoid receptor is of critical importance for the control of spatial behavioural functions, and (ii) mineralocorticoid receptor-mediated effects on this behaviour require interaction with functional glucocorticoid receptors. Until the development of site-specific, inducible glucocorticoid receptor mutants, glucocorticoid receptor-knockout mice present the only animal model for the study of corticosteroid-mediated effects in the complete absence of a functional receptor.     

Experimental and model investigations of bleaching and saturation of fluorescence in flow cytometry

We investigated the fluorescence emission from three fluorophores commonly used for labeling cells in flow cytometry. We have demonstrated that the fluorescence emission from cells labeled with fluorescein-isothiocyanate (FITC), phycoerythrin (PE), and allophycocyanin (APC) is considerably saturated and bleached in standard flow cytometric conditions. Therefore, for optimization of fluorescence detection in a flow cytometer, it is important to know the emission kinetics in detail. We made a mathematical model of the optical processes involved: absorption, fluorescence emission, nonradiative decay, photodestruction, and triplet state occupation. The validity of the model was experimentally tested with a set of averaged fluorescence pulses, measured in a large range of intensities and illumination times. The fluorescence of APC could be completely described by the model and produced the following rate constants: photodestruction rate kb1 = 6 x 10(3) s(-1), triplet state population rate k12 = 2 x 10(5) s(-1), and depopulation rate k20 = 5 x 10(4) s(-1). The fluorescence kinetics of FITC- and PE-labeled cells could not be fitted with only three parameters over the entire range, indicating that other optical processes are involved. We used the model to determine the sensitivity of our flow cytometer and to calculate the optimum conditions for the detection of APC. The results show that in principle a single APC molecule on a cell can be detected in the presence of background, i.e., autofluorescence and Raman scattering by water.     

Mixture-proportioning of high-performance concrete

The paper presents a new approach to design concrete mixtures. It is based upon a set of models relating composition and engineering properties of concrete, to be implemented into software, linked with a material database. The principles underlying the various models are summarized, most of which focus on the granular structure of fresh/hardened concrete. A global approach to concrete is promoted, where performance specifications can be formulated in terms of fresh concrete (yield stress, plastic viscosity, slump and air content), hardening concrete (adiabatic temperature rise and autogenous shrinkage) and hardened concrete (compressive strength at any age, tensile strength, elastic modulus, creep and shrinkage). This approach is illustrated through the design of a special high-shrinkage high-performance concrete (HPC) for road application. To date, durability is lacking in the model and requires further research.     

Magnetic field effects on g-jitter induced flow and solute transport

Numerical modeling and analyses are presented of magnetic damping of g-jitter driven fluid flow and its effect on the solutal striation in a simplified Bridgman-Stockbarger crystal growth system under microgravity. The model development is based on the finite element solution of the momentum, energy and solute transport equations under g-jitter conditions in the presence of an external magnetic field. The numerical model is verified by comparison with analytical solutions obtained for a simple parallel plate channel flow driven by g-jitter in a transverse magnetic field. Simulations are carried out to study the behavior of convective flow and solutal transport induced by the combined g-jitter and magnetohydrodynamic forces. Both the idealized single frequency g-jitter force and the real g-jitter perturbation taken during space flight are considered. Results indicate that an applied magnetic field can effectively damp the velocity caused by g-jitter and help to reduce the time variation of solute redistribution. A stronger applied field is more effective in suppressing the convective flows and hence reducing concentration variation. It is found that g-jitter driven flows have the same oscillation period as the driving force with or without the applied field. However, an applied magnetic field shortens the transient period over which the flow field evolves into a quasi-steady state time harmonic oscillation after g-jitter sets in. The flow intensity increases with an increase in g-jitter magnitude but decreases with an increase in the applied field strength. The reduced convection in the liquid pool by the applied magnetic field results in a reduction of the concentration oscillation. The magnetic field is very useful in suppressing the spiking velocities that are induced by the spikes in the real g-jitter data. The damping effect is more pronounced if the magnetic field is switched on before the onset of g-jitter disturbances.     

Trypanosoma cruzi: nitrogenous-base-containing phosphatides in trypomastigote forms--isolation and chemical analysis

Increasingly clinicians attempt to base decisions regarding patient management on the results of clinical studies in addition to expert opinion and their own practical experience. In this article, the author reviews the published studies available to assist clinicians to make evidence-based decisions in three topics related to small volume red blood cell (RBC) transfusions for preterm infants; namely, studies examining the effects of RBC transfusions on possible symptoms of anemia such as tachypnea, apnea or other cardiorespiratory irregularities, studies investigating the collection and transfusion of umbilical cord blood and finally studies addressing the duration of storage and use of additive solutions for RBCs for transfusion to neonates. Based on the review of these studies, guidelines for small volume RBC transfusions in preterm infants are suggested.     

Opsonized zymosan stimulates the redistribution of protein kinase C isoforms in human neutrophils

We examined the ability of opsonized zymosan (OPZ) to stimulate translocation of protein kinase C (PKC) isoforms in human neutrophils. Neutrophils express five PKC isoforms (alpha, betaI, betaII, delta, and zeta), but little is known of their individual roles in neutrophil activation. As determined by immunoblotting, OPZ caused a time-dependent translocation of the predominant PKC isoforms (betaII, delta, and zeta) to neutrophil membranes, with a concomitant loss from the cytosol. Maximal translocation of all three isoforms occurred by 3 min. No PKC immunoreactivity was observed in a crude nuclear fraction, but PKC-delta and -zeta were found in the granule fraction after degranulation (10 min). PKC activity (Ca2+-dependent and -independent) increased 50- and 19-fold, respectively, by 10 min in the granules from OPZ-stimulated cells. Curiously, no immunoreactive cPKC (alpha and beta(I/II)) could be localized in the granule fraction to account for the Ca2+-dependent PKC activity. Localization of PKC isoforms in the neutrophil membranes and granules suggests their involvement in the regulation of functional responses triggered by OPZ. PKC isoform translocation to membranes from OPZ-stimulated cells preceded both p47phox (a cytosolic component of the NADPH oxidase) translocation and NADPH oxidase assembly. The presence of both PKC isoforms and p47phox in the membrane was transient, with the loss of p47phox occurring sooner than either the loss of membrane-associated PKC or that of NADPH oxidase activity. The apparent EC50 values for PKC translocation and NADPH oxidase assembly were similar. These data suggest that PKC isoforms regulate the assembly and activation of NADPH oxidase induced by OPZ.