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981.
The Internet has revolutionized the way software systems work. Many applications, such as online games and instant messengers, have utilized Web-related technologies to cooperate over the Internet. Recently, some researchers have utilized Web-related technologies in computer-aided design to allow real-time collaboration between users over the Web. All these systems are based on the client-server model. In this kind of collaborative design environment, the system grouping, operation, and communication all have to rely on the central server. In order to improve accessibility and flexibility in collaborative design and to provide a more load-balanced and extensible environment, this paper presents a prototype implementation of collaborative design tools based on a peer-to-peer (P2P) model. The users can conveniently form design groups by connecting directly to each other, anytime and anywhere, without the presence of a central server. All peers are equal in functionalities and computing loads. In addition, application level multicast (ALM) technology is adopted in the proposed system to improve efficiency in Internet communication. Based on the P2P network model and ALM communication scheme, several mechanisms are proposed in this paper to form a working model of this system. Then, the object model design and implementation of this P2P system is presented. 相似文献
982.
Antiviral activity and toxicity of fialuridine in the woodchuck model of hepatitis B virus infection
BC Tennant BH Baldwin LA Graham MA Ascenzi WE Hornbuckle PH Rowland IA Tochkov AE Yeager HN Erb JM Colacino C Lopez JA Engelhardt RR Bowsher FC Richardson W Lewis PJ Cote BE Korba JL Gerin 《Canadian Metallurgical Quarterly》1998,28(1):179-191
The crystal structure of the mouse major histocompatibility complex (MHC) class I molecule H-2Dd with an immunodominant peptide, designated P18-I10 (RGPGRAFVTI), from human immunodeficiency virus envelope glycoprotein 120 was determined at 3.2 A resolution. A novel orientation of the alpha3 domain of Dd relative to the alpha1/alpha2 domains results in significantly fewer contacts between alpha3 and beta2-microglobulin compared with other MHC class I proteins. Four out of ten peptide residues (P2 Gly, P3 Pro, P5 Arg and P10 Ile) are nearly completely buried in the Dd binding groove. This is consistent with previous findings that Dd exploits a four-residue binding motif comprising a glycine at P2, a proline at P3, a positively charged residue at P5, and a C-terminal hydrophobic residue at P9 or P10. The side-chain of P5 Arg is directed toward the floor of the predominantly hydrophobic binding groove where it forms two salt bridges and one hydrogen bond with Dd residue Asp77. The selection of glycine at P2 appears to be due to a narrowing of the B pocket, relative to that of other class I molecules, caused by Arg66 whose side-chain folds down into the binding cleft. Residue P3 Pro of P18-I10 occupies part of pocket D, which in Dd is partially split by a prominent hydrophobic ridge in the floor of the binding groove formed by Trp97 and Trp114. Residues P6 through P9 form a solvent-exposed bulge, with P7 Phe protruding the most from the binding groove and thereby probably constituting a major site of interaction with T cell receptors. A comparison of H-2Dd/P18-I10 with other MHC class I/peptide complexes of known structure provides insights into the possible basis for the specificity of the natural killer cell receptor Ly-49A for several related class I molecules. 相似文献
983.
L Berglund JL Witztum NF Galeano AS Khouw HN Ginsberg R Ramakrishnan 《Canadian Metallurgical Quarterly》1998,39(4):913-924
OBJECTIVE: This study was designed to determine whether simultaneous antegrade/retrograde cardioplegia improves myocardial perfusion in areas supplied by occluded vessels. METHODS: Isolated pig hearts placed in a Langendorff preparation were divided into two groups. The left anterior descending coronary artery was occluded at its origin. In group 1 (n = 7), simultaneous antegrade/retrograde cardioplegia was conducted with use of a single perfusion unit with tubing in a Y-shaped configuration at the end, joined to the aorta and the coronary sinus. In group 2 (n = 8) simultaneous antegrade/retrograde cardioplegia was performed with two separate units, one for antegrade delivery of cardioplegic solution and the other for retrograde cardioplegic solution delivery. Myocardial perfusion in the region supplied by the left anterior descending artery and the region not supplied by this artery was assessed by magnetic resonance imaging, with use of a magnetic resonance contrast agent. The contrast agent was introduced into the common perfusion line in group 1 and into the aortic line only in group 2. RESULTS: Magnetic resonance images showed that the myocardium in the region supported by the left anterior descending artery could not be perfused with antegrade cardioplegic solution because of occlusion of the artery. During simultaneous antegrade/retrograde cardioplegia, however, the myocardium in the left anterior descending region was perfused by approximately 40% to 50% (group 1) or 20% to 30% (group 2) of the degree of perfusion in the region not perfused by the left anterior descending artery (100%). Almost no cardioplegic solution was delivered to the heart through the coronary sinus route during simultaneous antegrade/retrograde cardioplegia in both groups of hearts. Myocardial perfusion in the region supported by the left anterior descending artery was heterogeneous during simultaneous antegrade/retrograde cardioplegia. CONCLUSIONS: Simultaneous antegrade/retrograde cardioplegia significantly improved myocardial perfusion in jeopardized areas of the myocardium. The jeopardized myocardium was mainly perfused by the solution drained from the adjacent normal tissue. Elevated pressure at the coronary sinus during simultaneous antegrade/retrograde cardioplegia is responsible for the redistribution of antegradely delivered cardioplegic solution. 相似文献
984.
Tzu Yun Chang Tan Fu Lei Tien Sheng Chao Huang Chun Wen Hsiao Wei Chen 《Electron Device Letters, IEEE》2002,23(7):389-391
This study describes a novel technique to form low temperature oxide (<350°C). Low-temperature oxides were formed by N2 O plasma in the plasma-enhanced chemical vapor deposition (PECVD) system with a CF4 pretreatment. These oxides demonstrate excellent current-voltage (I-V) characteristics comparable to thermally grown oxides. Experimental results indicate that CF4 plasma treatment can significantly improve the reliability of low-temperature oxides. With excellent electrical properties, the technique is highly promising for low-temperature processes 相似文献
985.
986.
PF Foster H Gebel BC McLeod N Ebert S Jensik HN Sankary A Tambur JW Williams 《Canadian Metallurgical Quarterly》1996,11(2):55-60
Our aim was to study the influence of infection with the respiratory syncytial virus (RSV) in non-hospitalized infants on sensitization to aeroallergens and the early manifestation of atopy. Six hundred and nine infants from the prospective German Multicenter Cohort Study on Atopy were included, 38% of whom had an elevated atopic risk. RSV IgG and IgM antibodies were tested by ELISA with gradient purified RSV antigen. Specific IgE against mites, cat dandruff, birch and grass pollens and relevant nutritional antigens were tested with CAP-RAST-FEIA (Pharmacia, Sweden). Of the cord sera 99% were positive for RSV-IgG, 44.7% at one year and 64.2% (n = 265) at two years of age. The positivity rate after 12 months varied with the season of birth, the number of siblings and the degree of exposure to tobacco smoke; and correlated closely with attacks of wheezing during infancy. Twenty (2.8%) children were found to be sensitized against at least one aeroallergen at one year, and 28 (10.5%) at two years. By the first birthday, mite sensitization (n = 3) could only be seen in the RSV-infected children; grass pollen sensitization (n = 9) was associated with RSV seropositivity (logistic regression model including the confounders mentioned above: with RSV IgG < p = 0.048 > and IgM < p = 0.0006 >), as was birch sensitization (n = 5) with RSV IgM (p = 0.009). No such differences could be detected at two years. No correlation of RSV seropositivity to any allergic manifestation could be found. We conclude, that it is only in the first year of life, that RSV infection plays a significant role in promoting sensitization against aeroallergens, which do not at this time produce allergic symptoms. 相似文献
987.
RC Sharma HN Hodis WJ Mack A Sevanian DM Kramsch 《Canadian Metallurgical Quarterly》1996,9(6):577-590
Oxy-free radicals may be involved in the pathogenesis of accelerated atherosclerosis in hypertension. We evaluated the direct antioxidant potential of probucol in hypertensive arteries by studying the spatial immunohistochemical distribution of three primary antioxidant enzymes (AEs). Nineteen normocholesterolemic New Zealand White rabbits were divided into two groups: normotensive controls (NT; n = 6) and 13 animals rendered hypertensive by surgical coarctation of abdominal aorta. The hypertensive group was subdivided into hypertensive alone (HT; n = 8) and hypertensive treated with 1% probucol (PO) for 9 weeks (HT-P; n = 5). Blood pressure rose significantly in both hypertensive groups (P < .005). At autopsy, both hypertensive groups showed similarly significant increases in mean arterial intima-media thickness (IMT) whether or not they were treated with probucol. However, only HT rabbits revealed significant increases in the intima-media depth penetration of glutathione peroxidase, superoxide dismutase, and catalase AEs. By contrast, in HT-P animals probucol produced significant reductions of immunostaining of all three AEs compared to the HT group (P < .05). Additionally, specific macrophage immunostaining revealed that the arterial wall of HT rabbits had numerous (10 to 12 per high power field) subintimal and medial macrophages as compared to the HT-P animals (1 to 2 per high power field). The blood pressure level correlated significantly with IMT in all three groups, but with depth penetration of the three AEs only in the NT and HT groups. Probucol, therefore, appears to act in concert with the native arterial antioxidant enzymes as a potent free radical scavenger to reduce oxidative stress and thus attenuate the macrophage invasive response in hypertensive arteries. 相似文献
988.
DA Devine MA Pearce SE Gharbia HN Shah RA Dixon R Gmür 《Canadian Metallurgical Quarterly》1994,120(1-2):99-104
Prevotella intermedia and Prevotella nigrescens are not easily distinguished, making it difficult to assess their roles in disease. This study examined the specificity of three monoclonal antibodies (mAbs) for these species. Differentiation between P. intermedia (13 isolates) and P. nigrescens (24 isolates) was by the electrophoretic mobility of their malate and glutamate dehydrogenase enzymes or by DNA homology grouping. All P. intermedia reacted strongly with mAb 40BI3.2.2 whereas P. nigrescens strains did not. Monoclonal antibodies 37BI6.1 and 39BI1.1.2 recognised all strains of both species but most P. nigrescens reacted weakly with mAb 39BI1.1.2. Monoclonal antibody 40BI3.2.2 therefore recognises an antigen specific for P. intermedia but not P. nigrescens and provides an easy and reliable means of distinguishing between these species. Three vaginal isolates identified biochemically as P. intermedia had enzymes with mobilities corresponding to neither P. intermedia nor P. nigrescens. These isolates were not recognised by mAbs 39BI1.1.2 or 40BI3.2.2 and may represent an undescribed taxon within this group of organisms. 相似文献
989.
Tien‐Tsorng Shih Jau‐Ji Jou Shun‐Shien Chu 《International Journal of Numerical Modelling》2016,29(2):301-308
The TO‐46 header has been commonly used for vertical cavity surface emitting laser (VCSEL) and photodetector package. The high‐frequency characteristics of a TO‐46 header were measured using our special K‐type adaptors and simulated through a three‐dimensional full wave electromagnetic simulator. The measurement and simulation results show the TO‐46 header provides a resonance‐free transmission bandwidth over 40‐GHz and reflection loss below −10‐dB within 31‐GHz, with an ideal 50‐Ω terminal. The 25‐Gb/s and 40‐Gb/s eye diagrams through a TO‐46 header were measured using our measurement setup, and the eye diagrams are clear enough. In addition, the single‐end and differential‐end equivalent circuit models of a TO‐46 header were established and verified. The TO‐46 header provides a low‐cost and high‐speed package solution and can be applied in 21‐Gb/s fiber channel technology and 100‐Gb/s (4 × 25‐Gb/s) Ethernet (100 GbE) network. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
990.
A method to solve the convex problems of nondifferentiable optimization relying on the basic philosophy of the method of conjugate gradients and coinciding with it in the case of quadratic functions was presented. Its basic distinction from the earlier counterparts lies in the a priori fixed constraint on the memory size which is independent of the accuracy of the resulting solution. Numerical experiments suggest practically linear rate of convergence of this algorithm. 相似文献