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  • 1
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This two-part paper is devoted to problems of structural-acoustic coupling with emphasis on analysis, design sensitivity analysis and optimization. Part II of the paper aims to (i) present consistent numerical techniques commonly used for treatment of coupled structural and acoustic dynamics, (ii) use the structural optimization tool ODESSY for solution of several coupled problems, and (iii) compare the numerical efficiency of alternative techniques and the relevance of selected objective functions.
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  • 2
    ISSN: 1615-1488
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper is devoted to problems of structuralacoustic coupling with emphasis on analysis, design sensitivity analysis and optimization. The paper is divided into two parts, and it is the aim of Part I to (i) give a brief survey of recent developments in sensitivity analysis and sound emission and NVH (Noise, Vibration and Harshness) design of acoustically loaded structures, and (ii) discuss alternative objective functions and optimization formulations for structural acoustics. The aims of Part II are to (i) present consistent numerical techniques commonly used for treatment of coupled structural and acoustic dynamics, (ii) use the structural optimization tool ODESSY for solution of several coupled problems, and (iii) compare the numerical efficiency of alternative techniques and the relevance of selected objective functions.
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  • 3
    ISSN: 1432-136X
    Keywords: Synthetic nutrient medium ; Cell multiplication ; Hemin ; Phospholipids ; Tetrahymena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ciliate Tetrahymena thermophila was grown in a synthetic nutrient medium at various amino acid concentrations. Before the beginning of the experiments the cells were starved for 4 h in a pH buffer. They were inoculated at an initial density of only 250 cells per ml. Under these conditions the cells grew and multiplied at only the two highest amino acid concentrations used. Hemin or phospholipids were found to stimulate cell growth at the lower amino acid concentrations. The mechanism behind this stimulatory effect is unknown, but may be connected with the maintenance of an adequate energy flow under adverse conditions. These additions represent an improvement of the synthetic medium for Tetrahymena.
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  • 4
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Die Ergebnisse von Experimenten mit Tieren führen zu der Feststellung, daß ein Fütterungszusatz von entweder Psyllium-Samenkernen oder Lignin das Verhältnis von Desoxycholsäure zu Chenodesoxycholsäure in der Galle ändert. In dieser Untersuchung scheint bei Patienten mit Gallensteinen eine akzeptable Dosis von Psyllium-Samenkernen oder Lignin die relativen Mengen von in der Galle befindlichem Cholesterin oder den einzeln verschiedenen Gallensäuren nicht zu ändern.
    Notes: Summary Animal experiments suggest that supplementing the diet with either psyllium seed husk or lignin alters the ratio of deoxycholic acid to chenodeoxycholic in bile. In this study dosages of psyllium seed husk or lignin acceptable to patients with gallstones do not appear to alter the relative amounts of cholesterol, or individual bile acids in the bile.
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  • 5
    ISSN: 1573-5036
    Keywords: ammonium ; nitrate ; split-roots ; root exudate ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of plant-root N-status on bacterial growth in the rhizosphere was studied with 5-week-old wheat plants grown in soil with low N content obtained by mixing 9:1 gravel:sandy loam. As a consequence of N limitation, significant increase in3Hthymidine (Tdr) incorporation rate occured 3 days after addition of 30 mM ammonium compared to controls without ammonium. Plants were grown with split-roots to separate the effect of soil N from effect of plant root derived organic matter-N on bacterial activity. The increase in nitrate concentration from 10 mM to 30 mM at one part of the root system led to significant increased3HT dr incorporation in the rhizosphere at the other part of root system after 4 days showing that the composition of root exudates became more favourable for bacterial growth when plants were fertilized with the higher level of nitrate.
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  • 6
    ISSN: 1572-9761
    Keywords: index ; dominance ; contagion ; fractal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantify aspects of spatial pattern that can be correlated with ecological processes. The present paper develops three indices of pattern derived from information theory and fractal geometry. Using digitized maps, the indices are calculated for 94 quadrangles covering most of the eastern United States. The indices are shown to be reasonably independent of each other and to capture major features of landscape pattern. One of the indices, the fractal dimension, is shown to be correlated with the degree of human manipulation of the landscape.
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  • 7
    ISSN: 1432-1424
    Keywords: Key words: Volume regulation — Phosphoinositidase C — Ins(1,4,5)P3— Ca2+signaling — K+ channels — Charybdotoxin — Clotrimazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. The putative role for Ca2+ entry and Ca2+ mobilization in the activation of the regulatory volume decrease (RVD) response has been assessed in Ehrlich cells. Following hypotonic exposure (50% osmolarity) there is: (i) no increase in cellular Ins(1,4,5)P3 content, as measured in extracts from [2-3H]myoinositol-labeled cells, a finding at variance with earlier reports from our group; (ii) no evidence of Ca2+-signaling recorded in a suspension of fura-2-loaded cells; (iii) Ca2+-signaling in only about 6% of the single, fura-2-loaded cells at 1-mm Ca2+ (1% only at 0.1-mm Ca2+ and in Ca2+-free medium), as monitored by fluorescence-ratio imaging; (iv) no effect of removing external Ca2+ upon the volume-induced K+ loss; (v) no significant inhibition of the RVD response in cells loaded with the Ca2+ chelator BAPTA when the BAPTA-loading is performed in K+ equilibrium medium; (vi) an inhibition of the swelling-induced K+ loss (about 50%) at 1-mm Ba2+, but almost no effect of charybdotoxin (100 nm) or of clotrimazole (10 μm), reported inhibitors of the K+ loss induced by Ca2+-mobilizing agonists. Thus, Ca2+signaling by Ca2+ release or Ca2+ entry appears to play no role in the activation mechanism for the RVD response in Ehrlich cells.
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  • 8
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyridoxylated adult human hemoglobin (HbAo) was prepared using a one molar equivalent of pyridoxal 5-phosphate (PLP) per heme and reduced with either NaCNBH3 or NaBH4. A separate sample was pyridoxylated and passed through a mixed-bed ion exchange column without reduction. All three preparations had a P50 of 29 ± 2 torr and a cooperativity of n = 2.4 ± 0.1. These preparations, in both the oxy and deoxy forms, were then treated with 7 equivalents of glutaraldehyde per tetramer at pH 6.8 at 4°C and at room temperature. The polymerization invariably reduced the P50 to 18 ± 2 torr with Hill coefficients of less than 2. These solutions, with or without further reduction using NaCNBH3, all retained the PLP in differing amounts (2-3 moles/tetramer). Methemoglobin concentrations were increased during the polymerization reaction. The normal pyridoxylation procedure, using sodium borohydride reduction, resulted in a number of different molecular species. Polymerization with glutaraldehyde caused a further proliferation of molecular species that could not be separated by anion exchange chromatography or by isoelectric focusing. The extent of polymerization, estimated by gel exclusion chromatography and SDS polyacrylamide gel electrophoresis, was from 40 to 50%. Analysis of the reverse phase chromatograms, which separate the heme and the α- and β-chains, showed extensive polymerization and distribution of the radioactively labeled PLP on the protein for all preparations. All of the polymerized and pyridoxylated samples were unstable, and showed different chromatographic patterns after storage at 4°C for 1 month. Attempts to stabilize these preparations by further reduction with NaCNBH3 gave products with a lower P50 and lower cooperativity. When the reactions were conducted with a purified HbAo, heterogeneity was somewhat decreased compared to the normally used stroma-free hemoglobin, but a large number of molecular species were still formed.
    Additional Material: 8 Ill.
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  • 9
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of chemically modified hemoglobin preparations have been proposed for use as an emergency resuscitation fluid. The purpose for forming these hemoglobin derivatives is to decrease the oxygen binding (i.e., to increase the P50) and to increase the intravascular retention time. These goals have been met with various degrees of success by using the reaction with pyridoxyl 5-phosphate to raise the P50, followed by the addition of glutaraldehyde to increase circulating half-life by polymerization.1,2 Other derivatives have been formed with polyethylene glycol,3,4 bis-(3,5-dibromosalicyl) fumarate,5,6 glycolaldehyde,7 and 2-nor-2-formylpyridoxal 5-phosphate,8,9 as well as with other compounds. All these derivatives introduce a foreign molecule into the hemoglobin, which may not always be desirable. Recently Tharp and Day10 used cyanogen to form intersubunit amide cross-links in hemoglobin without the incorporation of cyanogen. This approach is attractive if the appropriate functional properties can be attained. Takeda et al.11 showed that equimolar concentrations of amino acids and disuccinimidyloxalate could form peptide bonds in high yield. We report the characteristics of the hemoglobin molecule modified by internal covalent amide bonds, which may be a suitable candidate for a resuscitation fluid.
    Additional Material: 3 Ill.
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  • 10
    ISSN: 1432-1041
    Keywords: Lithium clearance ; furosemide ; circadian variations ; sodium ; potassium ; creatinine clearance ; electrolyte excretion ; renal tubular physiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of chronic furosemide treatment on the circadian cycle of lithium clearance (CLLi) and electrolyte excretion has been examined in 8 young, male volunteers, by performing two 24 h clearance experiments, before and after one week of treatment with furosemide 80 mg once daily. After 8 days on furosemide there was a significant decrease in creatinine clearance (−21%), plasma Na (−8.4 mM) and plasma K (−0.58 mM). At that time, however, there were no changes in 24 h-values of CLLi or Na excretion, although the magnitude of the circadian variation in CLLi and other renal parameters was increased. Both CLLi and CLNa were increased in the first 3 h following furosemide administration and thereafter they fell below the control level in the remaining hours of the experiment. From the absolute and fractional changes in CLLi it is suggested that compensatory Na conservation in response to chronic furosemide treatment occurs between doses, and that it involves decreased output from the proximal tubules combined with increased fractional Na reabsorption in the distal nephron.
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