A Jordan control canonical form for singular systems

A canonical form for controllable singular systems modulo restricted system equivalence is presented. The canonical form respects the decomposition of the singular system into a regular and an impulsive part. The construction is based on Popov's control canonical form and on the Jordan canonical form recently developed by Hinrichsen and Prätzel-Wolters. Continuity properties are analysed and the cellular partition of the orbit space induced by the canonical form is briefly discussed.     

直接转矩控制研究现状与前景

介绍了直接转矩控制的研究现状，就几个关键问题进行了讲座，并分析了其今后的发展方向。     

Management of upper urinary tract calculi with ureteroscopic techniques

Frequent loss of heterozygosity on chromosome 8p in a variety of human malignancies, including head and neck cancers, has suggested the presence of a tumor suppressor gene (or genes) associated with the pathogenesis of these cancers. To test the role of genetic alterations at 8p23 in oral carcinogenesis, we studied 51 squamous cell carcinomas of the head and neck and 29 oral squamous cell carcinoma cell lines for allelic loss using 7 microsatellite markers spanning approximately 5 cM of chromosome band 8p23. Twenty-three of 51 tumors (45%) and 23 of 29 cell lines (79%) showed allelic loss at 1 or more loci. Three cell lines showed homozygous deletion of loci within a 3 cM region defined by the markers D8S1781 and D8S262. Our results suggest that a tumor suppressor gene (or genes) is located in 8p23 and is associated with the development and/or progression of oral carcinomas.     

Comparison of arterialized venous sampling from the hand and foot in the assessment of in vivo glucose metabolism

To determine whether arterialized venous blood obtained from a foot vein could be substituted for arterialized venous blood obtained from a hand vein during studies using the glucose clamp technique, we simultaneously measured glucose concentrations and PO2 in blood samples obtained from the heated hands and feet of five normal volunteers during the euglycemic and hyperglycemic steps of a hyperinsulinemic clamp. Plasma glucose concentrations were found to be virtually identical in arterialized venous blood drawn from the hand and the foot under both euglycemic and hyperglycemic conditions. The correlation between these values was significant (R2 = .99, P < .001). PO2 measurements in blood drawn from the heated hand or foot were not statistically different. We conclude that the glucose concentration measured in arterialized venous blood drawn from the foot is equivalent to the concentration in arterialized venous blood drawn from the hand. These observations will allow investigators to study in vivo glucose metabolism in individuals with poor venous access in the upper extremities and to use protocols that make the arms of the subject inaccessible for blood sampling during the study.     

Human and monkey trabecular meshwork accumulate alpha B-crystallin in response to heat shock and oxidative stress

PURPOSE: Oxidative stress and other forms of injury to trabecular meshwork (TM) cells may contribute to changes seen with age and primary open-angle glaucoma. This study was designed to investigate if TM expresses alpha B-crystallin, a small heat-shock protein with chaperone activity, and whether it might be overexpressed under stress conditions. METHODS: The TM from human and monkey eyes, as well as organ and primary cell cultures derived from these eyes, were investigated for alpha B-crystallin by immunohistochemistry, two-dimensional gel electrophoresis, Northern and Western blot analysis. The TM cell cultures were stressed by heat shock (44 degrees C for 15 minutes) or hydrogen peroxide (200 mumol for 1 hour). Semiquantitation of alpha B-crystallin messenger RNA (mRNA) or protein was obtained by densitometry. RESULTS: In both species, alpha B-crystallin could be detected in fresh and cultured TM by two-dimensional gel electrophoresis in conjunction with Western blot analysis. Immunohistochemistry of fresh samples showed that alpha B-crystallin was expressed predominantly in the cribriform area. Protein expression was enhanced in 4- to 7-day organ cultures. Primary cultures from human TM cells expressed two sizes (approximately 0.8 and 1.1 kb) of alpha B-crystallin mRNA in Northern blots. In monkey TM cultures, a 0.8-kb band was observed, which comigrated with lens alpha B-crystallin. In both species, heat shock caused a significant increase in alpha B-crystallin mRNA with a peak after 4 hours. An increase in alpha B-crystallin mRNA also was observed after oxidative stress; however, the onset of mRNA induction was slower. After heat shock, but not after oxidative stress, a transient change in mRNA mobility was observed. Western dot blot analysis showed a 3.4-fold increase in protein 24 hours after heat shock and a 20-fold increase after 48 hours. No constitutive mRNA expression and only a minimal increase 4 hours after heat shock could be observed in simian virus 40 transformed cell lines from human TM. CONCLUSIONS: Overexpression of alpha B-crystallin might be an important mechanism for TM to prevent cellular damage associated with various stress conditions.     

云中基于蚁群算法改进的负载均衡策略

针对云计算虚拟化资源中,提高资源利用率、负载均衡度的问题,在蚁群算法的基础上,提出云中节点间负载均衡的改进算法。前向蚂蚁检测节点的类型、记录节点信息,遇到负载节点时留下觅食信息素;后向蚂蚁依据循迹信息素追溯回负载节点,合理分配超载节点任务。所有蚂蚁不再更新自己的结果集,而是致力于更新单个结果集,在搜索过程中依据节点类型动态地修改路径信息素。在Cloudsim平台下进行的仿真实验验证了改进算法的有效性。