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21.
Prepulse inhibition (PPI) refers to a reduction in the startle response to a strong sensory stimulus when this stimulus is preceded by a weaker stimulus--the prepulse. PPI reflects a nonlearned sensorimotor gating mechanism and also shows a robust gender difference, with women exhibiting lower PPI than men. The present study examined the eyeblink startle responses to acoustic stimuli of 59 healthy heterosexual and homosexual men and women. Homosexual women showed significantly masculinized PPI compared with heterosexual women, whereas no difference was observed in PPI between homosexual and heterosexual men. These data provide the first evidence for within-gender differences in basic sensorimotor gating mechanisms and implicate the known neural substrates of PPI in human sexual orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
22.
N‐p‐Bromophenylmaleimide (BrPMI) does not polymerize in solution by conventional free radical mechanism. However, it readily polymerized in bulk when mixed with a free radical initiator and heated in a microwave oven for 7–8 min. Copolymerization of ethyl methacrylate or butyl methacrylate with BrPMI was conducted in dioxane. The copolymers were characterized by IR and 1H NMR spectroscopy and gel permeation chromatography. The monomer reactivity ratios were calculated by a non‐linear least‐square analysis. Thermal analysis indicated a great improvement in thermal stability of the copolymers compared with the methacrylate homopolymers. BrPMI was also polymerized in bulk in the DSC pan, which allowed the calculation of the activation energy of its polymerization. Copyright © 2003 Society of Chemical Industry 相似文献
23.
The present classification systems of kerogens have many shortcomings, especially in respect of amorphous kerogens which have, so far, remained undifferentiated in relation to hydrocarbon generation. Hence, a practical classification method based on density separation, elemental composition and optical characteristics, which discriminatingly identifies kerogens with indications of their hydrocarbon potential, has been developed. The method first divides the whole range of kerogens into liptinite and humic groups. The liptinitic kerogens are subdivided into Hyperliptinites (prolific oil sources); Mesoliptinites (which are oil-prone); Metaliptinites (gas-prone); and Hypoliptinites (having no potential for hydrocarbons). The humic kerogens are similarly divided into subgroups consisting of Hyperhumics (with some gas potential); Mesohumics (mainly gas sources); and Hypohumics (organic materials with no potential for hydrocarbon generation). 相似文献
24.
Akon Mohammad Mursalin Asaduzzaman Shah Rahman Md. Saidur Matsumoto Mitsuji 《Telecommunication Systems》2004,25(3-4):287-298
A routing protocol chooses one of the several paths (routes) from a source node to a destination node in the computer network, to send a packet of information. In this paper, we propose a new routing protocol, which we call st-routing protocol, based on st-numbering of a graph. The protocol fits well in noisy environments where robustness of routing using alternative paths is a major issue. The proposed routing protocol provides a systematic way to retry alternative paths without generating any duplicate packets. The protocol works for only those networks that can be represented by biconnected graphs. 相似文献
25.
A complete model is presented in this article for design optimization of hydraulic fracturing to enhance reservoir production. The model integrates reservoir properties, various design constraints to avoid induced formation damage, a hydraulically driven fracture geometry model, a hydrocarbon production model, and an economic model in deciding on the optimum values of various treatment parameters. The design constraints are intended to ensure that an optimum design obtained from the model can be executed in the field using the specified surface equipment and without causing uncontrolled fracture growth and/or initiation of multiple secondary fractures. A pseudo-3D fracture model is improved to establish better compatibility relationships between reservoir properties, treatment parameters, and fracture growth. Features of Genetic Algorithm and Evolutionary Operation are combined to develop a robust optimization algorithm that executes complex interactions between the above-mentioned modules to achieve an optimum design. The capability and robustness of the proposed model is demonstrated by applications to a tight-gas reservoir. By trade-off analysis between production/NPV and treatment cost, it is shown that only a 13% sacrifice of the maximum possible production/net present value (NPV) over ten years can save up to 52% of the fracturing treatment cost. Various other design issues are also investigated by sensitivity analyses. 相似文献
26.
Rajarajan M. Rahman B.M.A. Wongcharoen T. Grattan K.T.V. 《Lightwave Technology, Journal of》1996,14(9):2078-2084
The accurate analysis of multimode interference (MMI) devices with two-dimensional (2-D) confinement has been demonstrated by using the least squares boundary residual (LSBR) method. Accurate modal propagation constants and spatial field profiles in the MMI section are obtained by using the vector H-field based finite element method. The accurate calculation of the excited modal coefficients is achieved by using the LSBR, which satisfies the continuity of the transverse field components more rigorously than using simple overlap integrals 相似文献
27.
HR Lieberman MZ Mays B Shukitt-Hale KS Chinn WJ Tharion 《Canadian Metallurgical Quarterly》1996,67(9):841-848
PURPOSE: We wanted to determine whether sleep is disrupted when soldiers sleep in a new chemical protective mask, the M40. Sleep quantity and quality, extent of protection provided by the mask during sleep, and next day performance were assessed. METHOD: After several days of training, 9 male soldiers slept with and without the M40 mask on four occasions. RESULTS: Soldiers were able to tolerate the mask for most or all of the night. However, sleep, as assessed by wrist-worn activity monitors, was significantly disturbed. Minutes (mean +/- SEM) of waking significantly increased, from 25 +/- 2.1 to 86 +/- 8.5 per night (p < 0.001), and number of awakenings rose from 8 +/- 0.6 to 20 +/- 0.9 (p < 0.0001). Soldiers reported that it took longer and was more difficult to fall asleep when wearing the mask. Errors on a choice reaction time task increased significantly and subjects reported greater fatigue and sleepiness the day after sleeping in the mask. Protection provided by the masks varied substantially among subjects and declined over the course of the study. Some soldiers were protected throughout the night but others were only protected intermittently. CONCLUSION: We conclude that sleeping in the chemical protective mask should only be done when necessary, given the adverse effects on sleep and daytime function, as well as the variability of protection, of the mask. 相似文献
28.
Preretinal neovascularization and chronic retinal oedema are the two major sight-threatening complications that can occur during diabetic retinopathy. Ocular neovascularization is strongly associated with retinal ischaemia, and growth factors have been implicated in its pathogenesis. The ischaemic retina is assumed to secrete growth factors that stimulate residual vessels to proliferate. Interest has focused on basic fibroblast growth factor (bFGF), insulin-like growth factor-1 (IGF-1), platelet-derived growth factor (PDGF), transforming growth factor beta (TGF beta) and more recently vascular endothelial cell growth factor (VEGF). Histologic studies have demonstrated the presence of growth factor proteins and receptors and/or their mRNA, mainly VEGF, PDGF, and bFGF, in preretinal membranes of patients with proliferative diabetic retinopathy. Elevated intravitreal levels of IGF-1 and VEGF correlating with neovascular activity have been found in some patients. However, a direct causal relationship between ischaemia, growth factors and neovascularization has not been clearly demonstrated despite considerable research work. To date, the growth factor correlating most closely with neovascularization is VEGF. As many growth factors seem to be produced during the neovascular process, their specific inhibition probably will have limited effects. Laser photocoagulation of the retina has proved beneficial for regression of new vessels, probably through destruction of the ischaemic retina producing neovascular growth factors, and is currently the only treatment for proliferative diabetic retinopathy. Inhibition of IGF-1 by somatostatin analogs has produced unsatisfactory results. Other vascular inhibitors are currently being studied. 相似文献
29.
This article presents application of a hybrid method for modelling discrete fracture network in an actual naturally fractured reservoir (NFRs) (Palm Valley, Australia). The hybrid method integrates features of geological, statistical, artificial intelligence, and conditional hierarchical stochastic simulation techniques. Both discrete and continuum fracture information could be utilized, such as statistical distributions of fracture orientations, spatial distributions of fracture density, and discrete multi-fractal dimensions. The final output is a 3D network model of discrete fractures, with their corresponding details of location, size, and orientation. The results show an improvement of the hybrid method over previous fracture models. 相似文献
30.