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851.
M. Langthjem 《Structural and Multidisciplinary Optimization》1994,7(4):227-236
A non-uniform, elastic cantilever, with Kelvin-Voigt internal damping and viscous external damping, subjected to a follower load at its free end, is considered. The mass/stiffness distribution of the column is described by a limited number of orthogonal design functions. For different values of internal and external damping, the mass distribution maximizing the critical load is found. The design improvements are based on analytical sensitivity analysis and the optimal linear combination of the design functions is found by sequential linear programming. Interaction of eigenvalues and the transference of the instability branch during optimization are discussed. Finally, the energy relations for the critical modes are considered. 相似文献
852.
Staurosporine (STAR) is one of the most potent inhibitors of protein kinase C (PKC). It is known that in human polymorphonuclear leukocytes (PMNs), the phorbol ester-induced generation of superoxide anion (respiratory burst) is effectively inhibited by STAR in a dose-dependent manner, whereas superoxide generation induced by chemoattractants, e.g. n-formyl-methionyl-leucyl-phenylalanine (FMLP) or PAF, is regulated biphasically by STAR. We compared the effects of STAR and K252a on FMLP-induced superoxide production from PMNs and examined the effects of propranolol, a inhibitor of phosphatidic acid (PA) phosphohydrolase, on the potentiation of the production by STAR. We also examined the effects of some derivatives of STAR and K252a on the production and the alteration of the effects induced by propranolol pretreatment. When PMNs were stimulated with FMLP, STAR potentiated superoxide production by 240.5 +/- 30.9% at a low concentration (100 nmol/l). Propranolol pretreatment specifically inhibited the potentiation. When phorbol-12-myristate-13-acetate (PMA) was used as a stimulant, STAR inhibited superoxide production dose-dependently and did not enhance the production. K252a inhibited PMA or FMLP-induced superoxide production dose-dependently and did not enhance FMLP-induced superoxide production. STAR derivatives showed potentiation of FMLP-induced superoxide production similar to that of STAR at concentrations ranging from 10-100 nmol/l, and propranolol (200 mumol/l) effectively inhibited it. K252a derivative NA332 did not show any potentiative effect on the production. PMA-induced superoxide production was inhibited by all compounds dose-dependently.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
853.
854.
B Conrad E Weidmann G Trucco WA Rudert R Behboo C Ricordi H Rodriquez-Rilo D Finegold M Trucco 《Canadian Metallurgical Quarterly》1994,371(6495):351-355
Insulin-dependent diabetes mellitus (IDDM) is a T-cell-mediated autoimmune disease whose onset is believed to be triggered by unknown environmental factors acting on a predisposing genetic background. Islet-infiltrating T (IIT) cells from two IDDM patients, who had died at the onset of the disease from brain swelling as a complication of ketoacidosis, were analysed. The results provided evidence for the involvement of a pancreatic islet cell membrane-bound superantigen as a diabetes aetiopathogenetic factor. There was a selective expansion of a T-cell receptor (TCR) variable segment of the beta-chain (V beta 7) in these IIT cells in association with unselected V alpha-chain segments; extensive junctional diversity of the TCR V beta 7 chains; and evidence of positive selection, after exposure to diabetic islet cell membrane preparations, of V beta 7+ T-cell clones among peripheral blood lymphocytes from non-diabetic individuals. 相似文献
855.
Laparoscopic pelvic lymph node dissection has been applied as a minimally invasive staging technique for men with prostate cancer. This procedure has been shown to shorten markedly postoperative hospitalization, decrease analgesic requirements and shorten convalescence period compared to open pelvic node dissection. However, the laparoscopic procedure takes longer to perform and many disposable instruments are used, thus increasing the cost. We determine the overall cost of laparoscopic versus open pelvic lymph node dissection. Between January 1989 and April 1992, 61 men underwent only staging pelvic lymph node dissection for cancer of the prostate at a single university teaching hospital. Of these patients 11 and 50 underwent open and laparoscopic pelvic lymph node dissection, respectively. Information from the hospital business office was reorganized into preoperative, intraoperative and postoperative expenses. All individual charges were transformed up or down to the dollar amounts of the 1990 to 1991 fiscal year so as to correct for inflationary changes. Preoperative costs were not significantly different between the 2 operative approaches. Intraoperative expenses were 52% greater if laparoscopic pelvic lymph node dissection was performed and can be explained by the longer operative times and use of disposable instrumentation. However, the postoperative period lasted an average of 1.61 days following laparoscopic pelvic lymph node dissection. Postoperative nursing and analgesic requirements were significantly more for patients undergoing open pelvic lymph node dissection. The overall postoperative costs following open pelvic lymph node dissection were 280% more expensive than for the laparoscopic procedure. The overall total costs were approximately $1,250 more for laparoscopic pelvic lymph node dissection. Wages lost or earned during this period and rapid return to normal activity following laparoscopic pelvic lymph node dissection would, in our opinion, justify this additional cost. 相似文献
856.
A comparison of HIV-1 and HIV-2 indeterminate Western blot patterns of Ghanaian sera collected between 1989 and 1990 was made. Antibodies to group specific antigen (GAG) gene products were most frequently detected both HIV-1 and HIV-2 indeterminate sera. HIV-2 GAG gene product p26 was shown to be a non-specific indicator of infection. Antibody to gp120, and envelope gene product of HIV-1 never occurred in indeterminate sera whereas antibodies to all the envelope gene products of HIV-2 were detected in indeterminate sera. 相似文献
857.
858.
Experience with electrical diagnostic and high-potential tests, performed at the terminals of unshielded cables in older nuclear and thermal plants is presented. The three basic types of cable-low- and high-voltage power cables, control cables and instrumentation cables-that are important to the reliable operation of a generating station and large industrial plants are described, and their aging mechanisms are indicated. Dielectric testing of unshielded cables, the effect of grounding, field testing of station cables, and insulation characterization at low frequencies are discussed 相似文献
859.
Macaroni was prepared from semolina fortified with 3, 6 and 9% CMC-protein (CMC — carboxymethyl cellulose) or HEC-protein (HEC — hydroxyethyl cellulose) complexes from whey and corn steep liquor to increase the protein quality and quantity. Fortification increased the protein content up to 14.2% in DM (vs. 12.1% in control) for macaroni. Water absorption, dough weakening and mixing tolerance index were decreased, while dough development time and dough stability were increased when the amount of precipitated cellulose-protein complex from whey and corn steep liquor in the blends increased. Addition of both tested cellulose-protein complexes improved cooking quality by increasing the weight and volume of cooked macaroni, but cooking losses were greater. Sensory evaluation of the colour, flavour and appearance of macaroni were improved as a result of adding cellulose-protein complex from whey. Macaroni samples prepared from dough mixtures with 6 and 9% of cellulose-protein complex from corn steep liquor were less acceptable than those prepared from 100% semolina. 相似文献
860.