Stability Analysis of Nonlinear Machining Force Controllers

Model parameters vary significantly during a normal operation, thus, adaptive techniques have predominately been used. However, model-based techniques that carefully account for changes in the force process have again been examined due to the reduced complexity afforded by such techniques. In this paper, the effect of model parameter variations on the closed-loop stability for two model-based force controllers is examined. It was found that the stability boundary in the process parameter space can be exactly determined for force control systems designed for static force processes. For force control systems designed for first-order force processes, it was found that the stability boundary is sensitive to the estimate of the discrete-time pole. The analysis was verified via simulations and experimental studie

Biological Activities and Applications of Dioscorins, the Major Tuber Storage Proteins of Yam

AbstractYam tubers, a common tuber crop and an important traditional Chinese medicine in Taiwan, have many bioactive substances, including phenolic compounds, mucilage polysaccharides, steroidal saponins and proteins. Among the total soluble proteins, 80% of them are dioscorins. In the past two decades, many studies showed that dioscorins exhibited biological activities both in vitro and in vivo, including the enzymatic, antioxidant, antihypertensive, immunomodulatory, lectin activities and the protecting role on airway epithelial cells against allergens in vitro. Some of these activities are survived after chemical, heating process or enzymatic digestion. Despite of lacking the intact structural information and the detail action mechanisms in the cells, yam dioscorins are potential resources for developing as functional foods and interesting targets for food protein researchers

A Semipersistent Plant Virus Differentially Manipulates Feeding Behaviors of Different Sexes and Biotypes of Its Whitefly Vector.

It is known that plant viruses can change the performance of their vectors. However, there have been no reports on whether or how a semipersistent plant virus manipulates the feeding behaviors of its whitefly vectors. Cucurbit chlorotic yellows virus (CCYV) (genus Crinivirus, family Closteroviridae) is an emergent plant virus in many Asian countries and is transmitted specifically by B and Q biotypes of tobacco whitefly, Bemisia tabaci (Gennadius), in a semipersistent manner. In the present study, we used electrical penetration graph (EPG) technique to investigate the effect of CCYV on the feeding behaviors of B. tabaci. The results showed that CCYV altered feeding behaviors of both biotypes and sexes of B. tabaci with different degrees. CCYV had stronger effects on feeding behaviors of Q biotype than those of B biotype, by increasing duration of phloem salivation and sap ingestion, and could differentially manipulate feeding behaviors of males and females in both biotype whiteflies, with more phloem ingestion in Q biotype males and more non-phloem probing in B biotype males than their respective females. With regard to feeding behaviors related to virus transmission, these results indicated that, when carrying CCYV, B. tabaci Q biotype plays more roles than B biotype, and males make greater contribution than females

Heparinization on pericardial substitutes can reduce adhesion and epicardial inflammation in the dog

AbstractObjective: Primary concerns about currently available pericardial substitutes include adhesion and epicardial reaction. The purpose of this study is to evaluate host reaction to pericardial substitutes with and without incorporating slow heparin release. Methods: To avoid biologic variation among these pericardial patches, we made a composite of six membranes. The composite membrane consisted of epoxy-fixed patches with (1) or without (2) ionically bound heparin, a glutaraldehyde-fixed patch with (3) or without (4) ionically bound heparin, an expanded polytetrafluoroethylene patch (5), and a polyester polymeric patch (6). Ten recipient dogs weighing from 12 to 19 kg (mean 13.6 kg) were used to assess the composite membranes as pericardial substitutes. The implanted composite membranes were retrieved 1 week (one dog), 2 weeks (one dog), 4 weeks (one dog), 8 weeks (one dog), and 12 weeks (six dogs) after implantation. Results: Overall, the synthetic patches had a more notable inflammatory reaction than the biologic patches with or without ionically bound heparin. The heparin-bound patches caused significantly less inflammation than their nonheparinized counterparts. The heparinized porcine patches cross-linked with different compounds were found to have less fibrous formation than the nonheparinized patches and the synthetic patches. Conclusions: Heparinized pericardial substitutes may cause less adhesion and inflammatory reaction than nonheparinized material. (J Thorac Cardiovasc Surg 1998;115:1111-20

Wip1 and p53 contribute to HTLV-1 Tax-induced tumorigenesis

BACKGROUND: Human T-cell Leukemia Virus type 1 (HTLV-1) infects 20 million individuals world-wide and causes Adult T-cell Leukemia/Lymphoma (ATLL), a highly aggressive T-cell cancer. ATLL is refractory to treatment with conventional chemotherapy and fewer than 10% of afflicted individuals survive more than 5 years after diagnosis. HTLV-1 encodes a viral oncoprotein, Tax, that functions in transforming virus-infected T-cells into leukemic cells. All ATLL cases are believed to have reduced p53 activity although only a minority of ATLLs have genetic mutations in their p53 gene. It has been suggested that p53 function is inactivated by the Tax protein. RESULTS: Using genetically altered mice, we report here that Tax expression does not achieve a functional equivalence of p53 inactivation as that seen with genetic mutation of p53 (i.e. a p53(−/−) genotype). Thus, we find statistically significant differences in tumorigenesis between Tax(+)p53(+/+)versus Tax(+)p53(−/−) mice. We also find a role contributed by the cellular Wip1 phosphatase protein in tumor formation in Tax transgenic mice. Notably, Tax(+)Wip1(−/−) mice show statistically significant reduced prevalence of tumorigenesis compared to Tax(+)Wip1(+/+) counterparts. CONCLUSIONS: Our findings provide new insights into contributions by p53 and Wip1 in the in vivo oncogenesis of Tax-induced tumors in mice