光纤电视传输系统

本文综述了光纤电视传输系统的原理、构成、优点、主要技术指标和发展方向,并与现有的电视信号传输手段进行了技术经济分析比较。因此对各地电台说来,光纤已不再是明天的技术,而是今天就可实用的传输媒介。     

Measurement of resting cytosolic Ca2+ concentrations and Ca2+ store size in HEK-293 cells transfected with malignant hyperthermia or central core disease mutant Ca2+ release channels

Malignant hyperthermia (MH) and central core disease (CCD) mutations were introduced into full-length rabbit Ca2+ release channel (RYR1) cDNA, which was then expressed transiently in HEK-293 cells. Resting Ca2+ concentrations were higher in HEK-293 cells expressing homotetrameric CCD mutant RyR1 than in cells expressing homotetrameric MH mutant RyR1. Cells expressing homotetrameric CCD or MH mutant RyR1 exhibited lower maximal peak amplitudes of caffeine-induced Ca2+ release than cells expressing wild type RyR1, suggesting that MH and CCD mutants might be "leaky." In cells expressing homotetrameric wild type or mutant RyR1, the amplitude of 10 mM caffeine-induced Ca2+ release was correlated significantly with the amplitude of carbachol- or thapsigargin-induced Ca2+ release, indicating that maximal drug-induced Ca2+ release depends on the size of the endoplasmic reticulum Ca2+ store. The content of endogenous sarco(endo)plasmic reticulum Ca2+-ATPase isoform 2b (SERCA2b), measured by enzyme-linked immunosorbent assay, 45Ca2+ uptake, and confocal microscopy, was increased in HEK-293 cells expressing wild type or mutant RyR1, supporting the view that endoplasmic reticulum Ca2+ storage capacity is increased as a compensatory response to an enhanced Ca2+ leak. When heterotetrameric (1:1) combinations of MH/CCD mutant and wild type RyR1 were expressed together with SERCA1 to enhance Ca2+ reuptake, the amplitude of Ca2+ release in response to low concentrations of caffeine and halothane was higher than that observed in cells expressing wild type RyR1 and SERCA1. In Ca2+-free medium, MH/CCD mutants were more sensitive to caffeine than wild type RyR1, indicating that caffeine hypersensitivity observed with a variety of MH/CCD mutant RyR1 proteins is not dependent on extracellular Ca2+ concentration.     

Automatic diagnosis of diabetic retinopathy with the aid of adaptive average filtering with optimized deep convolutional neural network

The most effective treatment for diabetic retinopathy (DR) is the early detection through regular screening, which is critical for a better prognosis. Automatic screening of the images would assist the physicians in diagnosing the condition of patients easily and accurately. This condition searches out for special importance of image processing technology in the way of processing the retinal fundus images. Accordingly, this article plans to develop an automatic DR detection model with the aid of three main stages like (a) image preprocessing, (b) blood vessel segmentation, and (c) classification. The preprocessing phase includes two steps: conversion of RGB to Lab, and contrast enhancement. The Histogram equalization process is done using the contrast enhancement of an image. To the next of preprocessing, the segmentation phase starts with a valuable procedure. It includes (a), thresholding the contrast-enhanced and filtered images, (b) thresholding the keypoints of contrast-enhanced and filtered images, and (c) adding both thresholded binary images. Here, the filtering process is performed by proposed adaptive average filtering, where the filter coefficients are tuned or optimized by an improved meta-heuristic algorithm called fitness probability-based CSO (FP-CSO). Finally, the classification part uses Deep CNN, where the improvement is exploited on the convolutional layer, which is optimized by the same improved FP-CSO. Since the conventional CSO depends on a fitness probability in the improved algorithm, the proposed algorithm termed as FP-CSO. Finally, valuable comparative and performance analysis has confirmed the effectiveness of the proposed model.     

Comparative aroma profiles using supercritical carbon dioxide and Likens–Nickerson extraction from a commercial brand of Basmati rice

A comparative evaluation of the extraction of the aroma constituents of a popular commercial brand of Basmati rice using Likens–Nickerson extraction and supercritical fluid extraction (SFE) with carbon dioxide was carried out. SFE at 50 °C and 120 bar for 2 h provided appreciable extraction of the volatile constituents of the rice as compared with Likens–Nickerson extraction. The advantages of smaller sample size, shorter time of extraction and negligible possibility of artefacts with the SFE technique merit its use for recovery of aroma volatiles from Basmati rice. Copyright © 2003 Society of Chemical Industry     

Platelet GPIIb-IIIa blockers

Regardless of the event that stimulates the aggregation of platelets, the receptor alpha(IIb)beta3--one of a family of adhesion receptors known as integrins--has a key role in the process. The past decade has seen the publication of 10 phase III (randomised) clinical trials of four members of a new class of antiplatelet drugs, the GPIIb-IIIa blockers, targeted at this important receptor. Three (abciximab, eptifibatide, and tirofiban) are licensed for human use. 10 other GbIIb-IIIa blockers are in phase II or III human studies. In all 10 placebo-controlled trials, done in the clinical settings of percutaneous coronary intervention or acute coronary syndrome in patients on aspirin, the endpoints favoured the active drug, with a risk reduction for death or non-fatal myocardial infarction of about 21% overall. With attention to heparin dose the risk of bleeding is not a major concern with these agents. The GPIIb-IIIa blockers are taking the clinician and patient out of the era of aspirin monotherapy when platelet inhibition is required.