Distribution,Sources and Characterization of Polycyclic Aromatic Hydrocarbons in the Sediment of the River Gomti,Lucknow, India

Sediment samples were collected for PAHs analysis (upstream, midstream and downstream) from the bank of the river Gomti in Lucknow city, India during 2005–2007. Total concentration of the PAHs ranged from 0.068 to 3.153 μg/g dry weight. A correlation existed between the sediment organic carbon content (f _OC) and the total PAHs concentration with a correlation coefficient (r ²) of 0.788, suggesting that sediment organic carbon content played an important role in controlling the PAHs levels in the sediments. According to observed molecular indices, PAHs contamination in the river Gomti seems to be originated both from the high temperature pyrolytic process as well as from the petrogenic source, indicating a mixed PAH input pattern.     

酸处理对光敏玻璃离子边缘封闭性的影响

研究酸蚀对光敏玻璃离子的微渗漏影响。方法：采用侵害性窝沟封闭技术处理36颗人离休磨牙，并随机分成3组，每组12颗，第Ⅰ组为对照组，用37％磷酸酸蚀后，用低粘稠度复合树脂Liquicoat封闭窝沟裂隙。第Ⅱ组处理同第Ⅰ组，用低粘稠度光敏玻璃离子PrimaFlow封闭窝沟裂隙。第Ⅲ组与第Ⅱ组不同之处，对牙釉质不进行酸蚀。每组半数牙齿进行热循环处理（5～55℃，2500周）。所有标本用0．5％亚甲基蓝着色，在立体显微镜下观察微渗漏等级。结果：微渗漏第Ⅰ组与第Ⅱ组相似（P＞0．05）。第Ⅰ、Ⅱ组较第Ⅲ组小（P＜0．001）。复合树脂经热循环处理后微渗漏有增加（P＜0．01），而光敏玻璃离子粘固粉经热循环处理后微渗漏没有增加（P＞0．05）。结论：光敏玻璃离子结合酸蚀技术能减少微渗漏。     

Compression of radiological images with 512, 1,024, and 2,048 matrices

A comprehensive study was performed using the full-frame bit-allocation compression technique on 78 radiological images, including digitized radiographs, computed radiographs, and computed tomography images. Each radiograph was digitized to 2,048 X 2,048 X 10, 1,024 X 1,024 X 10, and 512 X 512 X 10 matrices, respectively, with a laser scanner. Five compression ratios were used to compress each image, and reconstructed images from each compressed data set were obtained. Altogether, the authors studied 842 images, including the original and compressed-reconstructed images and the images obtained from the difference between the original and the reconstructed images. The results indicate that acceptable compression ratios for 2,048, 1,024, and 512 matrices are 25:1, 20:1, and 10:1, respectively, based on a mean-square error of 0.02%.     

Nitroglycerin-induced headache is not dependent on histamine release: support for a direct nociceptive action of nitric oxide

The molecular mechanisms of migraine pain have not yet been clarified. Monoamine and the peptide neurotransmitters involved in neurogenic inflammation do not cause significant head pain. Our previous studies of glyceryl trinitrate (GTN) and histamine-induced headaches have suggested that nitric oxide (NO) is the causative molecule in migraine pain. We furthermore suggest that substances capable of inducing experimental vascular headache do so via a common mediator which is NO. Finally, it is suggested that drugs exert their antimigraine activity by inhibiting NO or subsequent steps in the cascade of intracellular reactions triggered by NO. These novel observations change current views on vascular headache mechanisms and the importance of NO as an initiator of the migraine attacks dictates new approaches to the pharmacological treatment of migraine and other vascular headaches.     

Quantifying Coevolution of Nonstationary Biomedical Signals Using Time-Varying Phase Spectra

We present a novel time-varying phase spectrum (TVPS) method to quantify the dynamics of coevolution of two persistent nonstationary coupled signals. Based on the TVPS, an instantaneous intersignal phase shift is defined within the primary frequency range in which the two signals are highly correlated. The TVPS is estimated using a fixed-window method or an adaptive-window method. In the latter method, the window length changes dynamically and automatically as a function of change in frequency of the signals. The effects of altering window types and lengths on the accuracy of the estimation of the primary phase shift is assessed by analyzing synthesized linear chirp signals with decaying amplitude and constant relative phase shift or decaying amplitude and changing relative phase shifts. The methods developed are also used for determining the evolution of the primary phase shift among ventral root activities during fictive locomotion in an in vitro rat spinal cord preparation. The analyses indicate that the TVPS method in conjunction with the determination of the primary frequency range, allows determination of both the evolution of the coupling strength and the evolution of the phase shift between two persistent nonstationary rhythmic signals in the joint time–frequency domain. An adaptive window reduces the estimation bias and the estimation variability. © 2000 Biomedical Engineering Society. PAC00: 0230-f, 8780Tq     

Polymerization of acrylonitrile initiated by the redox system manganese (III) acetate/ethylene glycol

The kinetics of polymerization of acrylonitrile initiated by the redox system manganese (III) acetate/ethylene glycol was studied in aqueous sulfuric acid medium in the temperature range from 30 to 40°C. The effect of varying the concentrations of monomer (M), acetic acid, and sulfuric acid and the addition of some electrolytes on the rate of polymerization (R_p) was investigated. Based on the experimental observations of the dependence of (R_p) on various parameters, a suitable kinetic scheme could be proposed. The plot of R_p²[M]² vs. [M] was found to be linear, a striking general phenomenon observed for all the substrates we have studied in this laboratory.     

Regulation of protein synthesis in rabbit reticulocyte lysates: characteristics of inhibition of protein synthesis by a translational inhibitor from heme-deficient lysates and its relationship to the initiation factor which binds Met-tRNAf.

In heme-deficient reticulocyte lysates a translational inhibitor which regulates protein synthesis is formed or activated. To define the mechanism of action of the translational inhibitor (RI), RI was partially purified. We have utilized the isolated RI to examine its relationship to the translational inhibitor formed in situ in heme-deficiency, some quantitative aspects of inhibition of protein synthesis, and the relationship of RI concentration to the initiation factor (IF-MP) which forms a ternary complex with Met-tRNAf and GTP (IF-MP-Met-tRNAf-GTP). The results demonstrate that the activity of isolated RI is related to the in situ heme-deficiency inhibitor by several criteria: (a) the biphasic kinetics of inhibition manifested by RI in lysates containing optimal levels of hemin are very similar to those observed in heme-deficiency, i.e., an initial period in which several rounds of protein synthesis proceed at the control rate followed by an abrupt decline in the rate of protein synthesis. (b) Both inhibitions are accompanied by the disaggreagation of polyribosomes with a concomitant increase in 80S ribosomes. (c) Both inhibitions are reversed by IF-MP. The isolated RI blocked protein synthesis in lysates at temperatures ranging from 15 degrees to 30 degrees. Although the rate of protein synthesis was a function of the temperature of incubation, the number of rounds of protein synthesis prior to shut-off was essentially the same at various temperatures. When RI was added to lysates, at increasing intervals after the start of incubation, the period of synthesis before shut-off (lag) progressively decreased. The inhibition of protein synthesis by RI was immediately reversed by the addition of IF-MP. The extent of reversal increased with increasing concentrations of IF-MP; at low levels of RI almost complete reversal of inhibition by IF-MP was obtained. However, at high levels of RI which did not appreciably increase the degree of inhibition of protein synthesis, equivalent amounts of IF-MP were less effective in reversing inhibition. These results suggest that the inhibition of protein synthesis by the isolated inhibitor involves the initiation factor IF-MP.     

Noninvasive Detection of Coronary Artery Stenosis Using 16-slice Spiral CT：a Comparison with Selective X-ray Coronary Angiography

Multislice spiral CT(MSCT)has recently e-volved as a modalityfor non-invasive coronaryi ma-ging.16-slice MSCT allows excellent distal coro-nary coverage with higer temporal and spatial reso-lution.It can be usedto detect stenosis of coronaryartery with a diameter≥1.5cm[1,2].We investi-gated a group of coronary MSCT angiography(MSCTA)results,with those of selective X-raycoronary angiography(SCA)serving as the refer-ence standard.1MATERIALS AND METHODS1.1PatientsBetween July20…