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  • 1995-1999  (4)
  • 1985-1989  (1)
  • Block downdating  (1)
  • Chemical Engineering  (1)
  • Codon usage  (1)
  • Cysteamine  (1)
  • Engineering  (1)
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Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Perturbation and error analyses for block downdating of a Cholesky decomposition (1996)
    Springer
    BIT 36 (1996), S. 247-263 
    Details
    ISSN: 1572-9125
    Keywords: Block downdating ; Cholesky decomposition ; condition number ; error analysis ; perturbation theory ; seminormal equations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A new perturbation result is presented for the problem of block downdating a Cholesky decompositionX T X = R T R. Then, a condition number for block downdating is proposed and compared to other downdating condition numbers presented in literature recently. This new condition number is shown to give a tighter bound in many cases. Using the perturbation theory, an error analysis is presented for the block downdating algorithms based on the LINPACK downdating algorithm and stabilized hyperbolic transformations. An error analysis is also given for block downdating using Corrected Seminormal Equations (CSNE), and it is shown that for ill-conditioned downdates this method gives more accurate results than the algorithms based on the LINPACK downdating algorithm or hyperbolic transformations. We classify the problems for which the CSNE downdating method produces a downdated upper triangular matrix which is comparable in accuracy to the upper triangular factor obtained from the QR decomposition by Householder transformations on the data matrix with the row block deleted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01731982
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of intrapancreatic neuronal activation on cholecystokinin-induced exocrine secretion of isolated perfused rat pancreas (1999)
    Springer
    Pflügers Archiv 437 (1999), S. 511-516 
    Details
    ISSN: 1432-2013
    Keywords: Key words Cholecystokinin ; Cysteamine ; Intrapancreatic neuron ; Islets ; Pancreatic secretion ; Pertussis toxin ; Somatostatin ; Somatostatin antagonist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The role of intrapancreatic neurons in the action of cholecystokinin (CCK) on pancreatic exocrine secretion of the totally isolated, perfused rat pancreas was investigated. Intrapancreatic neurons were activated by applying electrical field stimulation (EFS) to the isolated pancreas for 45 min. When applying EFS, spontaneous pancreatic secretions of fluid and amylase increased until the second 15-min period of EFS and then decreased during the third 15-min period. Atropine (2 µM) notably reduced the EFS-evoked pancreatic secretions of fluid and amylase. The CCK-induced (10 pM) pancreatic secretions of fluid and amylase elevated further in the first 15-min period of EFS and then gradually resumed to the levels observed during application of CCK alone in the third 15-min period of EFS. However, the CCK-induced pancreatic secretions remained elevated even in the third 15-min period of EFS when an action of endogenous somatostatin was inhibited by cyclo-(7-aminoheptanonyl-Phe-d-Trp-Lys-Thr[BZL]) (10 nM) or pertussis toxin (200 ng/ml). EFS further elevated spontaneous exocrine secretion by the cysteamine-treated (300 mg/kg) pancreas, but this was markedly reduced, to normal levels, by infusing somatostatin (100 pM). EFS increased the numbers of immunoreactive somatostatin cells in the Langerhans’ islets. The results indicate that intrapancreatic neuronal activation influences CCK-induced pancreatic secretions in a dual-phase pattern in the rat: an increase during the early phase and a decrease during the late phase. Endogenous somatostatin released from the islets appears to inhibit the enhancing effect of neuronal activation on CCK-induced pancreatic secretion. Of the intrapancreatic neurons, the cholinergic ones appear to predominate in EFS’s effects on CCK-induced pancreatic secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050811
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    NADH oxidase ofThermus thermophilus HB8 overproduced fromEscherichia coli (1995)
    Springer
    Protoplasma 184 (1995), S. 104-110 
    Details
    ISSN: 1615-6102
    Keywords: NADH oxidase ; Thermostable flavoprotein ; Affinity chromatography ; Codon usage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An NADH oxidase purified from the extreme thermophileThermus thermophilus HB8 is a monomeric flavoprotein with a 1 ∶ 1 ratio of flavin-adenine dinucleotide (FAD) to the polypeptide chain. It catalyzes in vitro the oxidation of reduced NADH or NADPH with the formation of H2O2. The gene encoding the NADH oxidase fromT. thermophilus HB8 was cloned, and its nucleotide sequence was determined. The molecular mass of 22,749 Da, as deduced from thenox gene, agrees with that of the purified NADH oxidase fromT. thermophilus HB8, as estimated by mass spectrometry. Thenox gene does not contain a GX4GK consensus sequence typical for nucleotide binding proteins. Thenox gene was overexpressed inEscherichia coli, and a protocol for the rapid purification of theE. coli-borneT. thermophilus NADH oxidase or its His6-tagged analogue was developed by using thermal denaturation step and affinity chromatography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276906
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    An efficient method of solving the Navier-Stokes equations for flow control (1998)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 41 (1998), S. 1133-1151 
    Details
    ISSN: 0029-5981
    Keywords: flow control ; numerical solution of Navier-Stokes equation ; Karhunen-Loève Galerkin procedure ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A new method of solving the Navier-Stokes equations efficiently by reducing their number of modes is proposed in the present paper. It is based on the Karhunen-Loève decomposition which is a technique of obtaining empirical eigenfunctions from the experimental or numerical data of a system. Employing these empirical eigenfunctions as basis functions of a Galerkin procedure, one can a priori limit the function space considered to the smallest linear subspace that is sufficient to describe the observed phenomena, and consequently reduce the Navier-Stokes equation defined on a complicated geometry to a set of ordinary differential equations with a minimum degree of freedom. The present algorithm is well suited for the problems of flow control or optimization, where one has to compute the flow field repeatedly using the Navier-Stokes equation but one can also estimate the approximate solution space of the flow field based on the range of control variables. The low-dimensional dynamic model of viscous fluid flow derived by the present method is shown to produce accurate flow fields at a drastically reduced computational cost when compared with the finite difference solution of the Navier-Stokes equation. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Rheological and mechanical characteristics of poly-p-phenylene terephthalamide/nylon molecular and particulate composites (1989)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 10 (1989), S. 429-438 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Poly-p-phenylene terephthalamide (PPTA) and nylons (nylon 6, 66, 11, and 12) molecular and particulate composites were examined with emphasis on rheological, mechanical, and morphological characteristics. These molecular composites were prepared by coagulation in water from isotropic ternary sulfuric acid solutions. Upon heating above the crystal melting temperatures of nylons, the molecular composites undergo phase separation and become two-phase particulate composites. Shear viscosity measurements indicate that the viscosity of nylon 6 and 66 systems has increased for an order of magnitude because of the presence of PPTA, but decreased in the case of nylon 11 and 12 systems. PPTA/nylon 6 and 66 systems exhibit yield behavior, particularly with high PPTA contents. Measurements show an extrudate swell of around 1 in all composition ranges and shear rates. Scanning electron microscopic investigations of low PPTA content particulate composites reveal spherical or long fibrillar morphology of PPTA phase dispersed in nylon matrices. Wide angle X-ray diffraction investigations show no preferred orientation in the extrudates, but biaxial orientation in the case of compressed films. The study on mechanical properties of extrudates of 5 to 10 wt.% PPTA compositions exhibits significant improvement in tensile modulus and tensile strength. The heat-treated extrudates show further increase in tensile modulus and tensile strength, as compared with the unannealed samples, but the elongation at break decreases.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750100607
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    Paper (German National Licenses)
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