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51.
A three-dimensional (3D) rock slope toppling occurred in a discontinuous rock mass. To simulate the failure process and study the mechanism of this rock failure with contact and large displacement in 3D, a new discrete numerical method has been developed called the 3D discontinuous deformation analysis (DDA). This article first introduces the basic principles and then derives the formulas in detail. Finally, the slope failure simulation is applied as an example to investigate the applicability of this new method to rock slope failure research. The simulation results indicate the advantages of using this new method to study the mechanism of a rock slope failure with 3D behavior.  相似文献   
52.
53.
A 51-year-old man inhaled sarin during a terrorist attack on the Tokyo subway system and died 15 months later. Neuropathologic examination revealed marked nerve fiber decrease in the sural nerve, moderate nerve fiber loss in the sciatic nerve, and unremarkable dorsal root ganglia, dorsal roots, and posterior column of the spinal cord. This pathology is consistent with dying-back degeneration of the peripheral nervous system and could represent a late sequela of sarin intoxication.  相似文献   
54.
OBJECTIVE: The American Diabetes Association has recommended that pregnant women with low-risk factors need not be tested for gestational diabetes mellitus (GDM). The aim of this study was to determine the prevalence of GDM in women with low-risk factors and to see if the pregnancy outcomes of women with GDM from a low-risk group were different from the outcomes of other women with GDM. RESEARCH DESION AND METHODS: Over an 18-month period, all pregnant women were offered a test for GDM using a 75-g glucose tolerance test at the beginning of the 3rd trimester. GDM was diagnosed if the 2-h glucose level was > or =8.0 mmol/l. The prevalence of GDM was determined in women with defined low-risk factors (Caucasian ethnic origin, age <25 years, and BMI <25 kg/m2). The pregnancy outcomes of women with GDM from a low-risk group were compared with those of other women with GDM. RESULTS: From a tested population of 2,907 women, 573 were identified as coming from a low-risk group. The prevalence of GDM in this low-risk group was 2.8%. The pregnancy outcomes of women with GDM from a low-risk group were no different from the pregnancy outcomes of other women with GDM, with respect to frequency of insulin use, units of insulin per day, morbidity, emergency caesarian section, and the percentage of both large- and small-for-gestational-age babies. In our population, if low-risk women were excluded, 80% of women would still require testing and nearly 10% of all cases of GDM would be missed. CONCLUSIONS: Women from a low-risk group have a 2.8% prevalence rate of GDM. The pregnancy outcomes of women with GDM from a low-risk group are similar to the outcomes of other women with GDM. Concerning the use of the 75-g glucose tolerance test in pregnancy, the recommendation not to test women from a low-risk group requires further evaluation in different populations before it can be endorsed.  相似文献   
55.
The authors present a near 1200 nm wavelength vertical-cavity surface-emitting laser (VCSEL) the active region of which is formed by GaInNAs/GaAs quantum wells grown by chemical beam epitaxy. Room temperature continuous-wave operation has been demonstrated with a high slope efficiency of 0.23 W/A, a high output power of over 1.0 mW, and a singlemode output power of 0.34 mW. The fabricated devices with different aperture sizes show low threshold currents of 1.2-2.1 mA and a record low threshold current density of 2.6 kA/cm2 in GaInNAs VCSELs  相似文献   
56.
Wireless mesh networks (WMNs) have attracted much attention due to their low up-front cost, easy network deployment, stable topology, robustness, reliable coverage, and so forth. These advantages are suitable for the disaster recovery applications in disaster areas, where WMNs can be advantageously utilized to restore network collapse after the disaster. In this paper, based on a new network infrastructure for WMNs, to guarantee high network performance, we focus on the issue of throughput optimization to improve the performance for WMNs. Owing to selecting different mesh router (MR) as the gateway will lead to different network throughput capacity, we propose a novel gateway selection technique to rapidly select the optimal MR as the gateway, in order to maximize the network throughput. In addition, we take into account the traffic distribution for the MR to eliminate traffic congestion in our method. The performance of our proposed method is evaluated by both numerical and simulated analysis. The simulation results demonstrate that the gateway selection method is effective and efficient to optimize the throughput for WMNs.  相似文献   
57.
Although iodine prevents goiter, enlarged thyroid glands continue to be detected in subjects, especially children, in spite of adequate iodine ingestion. Iodine may cause goiter in susceptible individuals by inhibiting the organic binding of iodine as is seen in adult asthmatics, neonates born of iodine ingesting mothers and in subjects residing along the littoral of Japan. Myxedema, especially in treated Graves' disease and Hashimoto's disease, may also be precipitated by iodine. On the other hand, iodine given to euthyroid subjects in areas of endemic goiter and to subjects with nontoxic nodular goiter may induce thyrotoxicosis by disclosing diffuse autonomously functioning thyroid tissue. An indirect adverse effect of iodine upon the thyroid gland may be manifested by lymphocyte glandular infiltrates and chronic thyroiditis which were sparse or absent in thyroid glands removed from subjects living in iodine deficient areas before iodine prophylaxis and therapy. Not only has the incidence of thyroiditis increased, but the histologic and clinical distinctions between treated Graves' disease and chronic thyroiditis have become indistinct. Experimentally, chronic thyroiditis has been produced in animals following large doses of iodine. Accumulated evidence supports the concept that iodine contributes to the genesis of chronic thyroiditis.  相似文献   
58.
Der f 2 is a major mite allergen composed of 129 amino acid residues. To determine the major epitopes on Der f 2 recognized by human IgE antibodies, artificial mutations were introduced to Der f 2 protein. The IgE-binding activity of Der f 2 was significantly decreased by deletion of 10 amino acids at the N-terminus or nine amino acids at the C-terminus. Site-directed mutagenesis with a single amino acid replacement by Ala or Leu in both N- and C-terminal regions as well as a central portion was performed to generate 42 single-site mutations. Amino acid replacement around a disulfide bond of Cys8-Cys119 caused a marked decrease in IgE-binding activity. Furthermore, a distinct decrease in IgE-binding was also caused by Ala-substitution close to a disulfide bond of Cys73-Cys78 and by mutations of a few charged residues. From these results, it was concluded that the two disulfide-forming regions of Der f 2 and several charged residues are important for forming major epitope structures recognized by human IgE antibodies.  相似文献   
59.
In recent time, a great deal of research effort has been directed toward promptly facilitating post-disaster communication by using wireless mesh networks (WMNs). WMN technology has been considered to be effectively exploited for this purpose as it provides multi-hop communication through an access network comprising wireless mesh routers, which are connected to the Internet through gateways (GWs). One of the critical challenges in using WMNs for establishing disaster-recovery networks is the issue of distributing traffic among the users in a balanced manner in order to avoid congestion at the GWs. To overcome this issue, we envision a disaster zone WMN comprising a network management center. First, we thoroughly investigate the problem of traffic load balancing amongst the GWs in our considered disaster zone WMN. Then, we develop traffic load distribution techniques from two perspectives. Our proposal from the first perspective hinges upon a balanced distribution of the bandwidth to be allocated per user. On the other hand, our second perspective considers the dynamic (i.e., varying) bandwidth demands from the disaster zone users that requires a more practical and refined distribution of the available bandwidth by following an intelligent forecasting method. The effectiveness of our proposals is evaluated through computer-based simulations.  相似文献   
60.
Oxygen incorporation for compensation of oxygen defects is investigated with La-silicate dielectrics in directly contacted with the Si substrate. The amount of oxygen is controlled by the temperature of annealing in oxygen atmosphere (oxygen annealing) and the thickness of the gate electrode. The positive shift in flatband voltage (VFB) by oxygen incorporation is an experimental evidence for defects compensation in La-silicate dielectrics. Optimum oxygen annealing provides the VFB shift toward positive direction without increasing equivalent oxide thickness (EOT). Although the oxygen annealing degrades the interfacial property at La-silicate/Si interface, subsequent forming gas annealing (FGA) can recover the interfacial property. It is experimentally revealed that the positive VFB shift of La-silicate dielectrics is stable even after subsequent FGA. The supplied oxygen in La-silicate is expected to maintain even after reducing process. Movement of Fermi level toward the Si valence band edge caused by oxygen incorporation is successfully observed by XPS. Moreover, no chemical reaction between La-silicate and Si substrate by oxygen annealing are confirmed from TEM observation and analyses of X-ray photoelectron spectra. It is experimentally demonstrated that effective hole mobility can be improved without increase in EOT by combination of oxygen annealing and FGA.  相似文献   
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