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  • 1
    Electronic Resource
    Electronic Resource
    The investigation of an unstable convective flow using optical methods (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 10 (1998), S. 2995-3008 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The convective flow field in a vessel is investigated by laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV, namely Particle Tracking Velocimetry—PTV). The vessel is heated from below along a linear element at a temperature higher than that of the fluid. Hot fluid raises up and generates two counterrotating vortices. For a given aspect ratio, the two vortices become unstable and start to oscillate on a vertical plane (orthogonal to the heating element). This regime is investigated for increasing Rayleigh numbers to analyze the transition from regular to irregular conditions. The main transition mechanism is observed to be mostly connected to type II intermittency, a mechanism not frequently observed in experiments. However, at some Rayleigh numbers the present data does not definitely rule out type III intermittency. The phenomenon is analyzed by looking at the main frequencies in the spectrum of the horizontal velocity component and their changes with the Rayleigh number at a point above the heating element. Modifications in the local energy spectrum are analyzed by using the Wavelet Transform (WT) tool. Data obtained by PTV measurements make it possible to point out the spatial configuration of the flow and to determine the two velocity components on the measurement plane. These data are used to clarify the fundamental mechanisms of the transition. Instabilities are observed as sudden changes between two regimes of oscillations of the two counterrotating vortices: the first is characterized by oscillations centered on the vertical axis and the second by nonsymmetrical oscillations. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.869819
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  • 2
    Electronic Resource
    Electronic Resource
    The insidious effect of diatoms on copepod reproduction (1999)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 402 (1999), S. 173-176 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The productive regions of the ocean are characterized by seasonal blooms of phytoplankton which are generally dominated by diatoms. This algal class has, therefore, traditionally been regarded as providing the bulk of the food that sustains the marine food chain to top consumers and important ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/46023
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  • 3
    Electronic Resource
    Electronic Resource
    Physical state and biodegradation behavior of starch-polycaprolactone systems (1995)
    Springer
    Journal of polymers and the environment 3 (1995), S. 81-95 
    Details
    ISSN: 1572-8900
    Keywords: Biodegradation ; poly-ε-caprolactone ; starch ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The biodegradation behavior of insoluble crystalline polymers depends on both chemical structure and physical state. The physical state is strongly affected by the molding conditions; moreover the presence of natural hydrophylic substances such as starch can further influence the biodegradation process. This paper examines the biotic and abiotic degradation of thick injection-molded parts, made of pure poly-ε-caprolactone (PCL) at different molecular weights, and of PCL in the presence of starch in the case of a commercial grade of Mater-Bi, produced by Novamont. The abiotic degradation was studied at 25 and 50°C, whereas the biotic degradation was followed in conditions of SCAS (semicontinuous activated sludges) at 25 and 50°C, soil burial, and controlled composting. The physical-chemical modifications provoked at the surface and in the bulk of the samples by the different types of degradation were determined by differential scanning calorimetry, viscometric and gravimetric analysis, scanning electron microscopy, and dynamic mechanical analysis. The mechanical modifications induced by the different environments were followed by tensile tests. It was demonstrated that the presence of starch significantly increases the apparent biodegradation rate of PCL, making even thick parts of ZI01U compatible with the composting process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02067484
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  • 4
    Electronic Resource
    Electronic Resource
    New results in subdifferential calculus with applications to convex optimization (1995)
    Springer
    Applied mathematics & optimization 32 (1995), S. 213-234 
    Details
    ISSN: 1432-0606
    Keywords: Convex analysis ; Subdifferentials ; Chain rules ; Optimization ; Primary 4902 ; Secondary 49J52
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Chain and addition rules of subdifferential calculus are revisited in the paper and new proofs, providing local necessary and sufficient conditions for their validity, are presented. A new product rule pertaining to the composition of a convex functional and a Young function is also established and applied to obtain a proof of Kuhn-Tucker conditions in convex optimization under minimal assumptions on the data. Applications to plasticity theory are briefly outlined in the concluding remarks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01187900
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  • 5
    Electronic Resource
    Electronic Resource
    Very low density lipoprotein subfraction abnormalities in IDDM patients: any effect of blood glucose control? (1995)
    Springer
    Diabetologia 38 (1995), S. 1419-1424 
    Details
    ISSN: 1432-0428
    Keywords: Lipoproteins ; VLDL subfractions ; insulin-dependent diabetes mellitus ; blood glucose control ; lipid concentration ; lipolytic enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Normolipidaemic insulin-dependent diabetic (IDDM) patients are characterized by an increase in the smaller VLDL particles, considered to be the most atherogenic. Since blood glucose control is one of the main regulators of lipid metabolism in diabetic patients, it could influence the shift in the distribution of VLDL subfractions towards smaller particles. To evaluate this possibility, VLDL subfractions, post-heparin lipoprotein lipase and hepatic lipase activities have been evaluated in male IDDM patients with either unsatisfactory blood glucose control (group 1, HbA1c〉8%, n=18) or good blood glucose control (group 2, HbA1c〈8%, n=16) and in 16 normoglycaemic individuals. The three groups were comparable for sex, age, body mass index, and plasma lipid levels. Three VLDL subfractions (large, Svedberg flotation unit (Sf) 175–400; intermediate, Sf 100–175; small, Sf 20–100) were separated by density gradient ultracentrifugation and analysed for cholesterol, triglyceride, and phospholipid levels. When compared to control subjects both groups of IDDM patients showed a clear shift in VLDL subfraction distribution with a significant increase in the proportion of small VLDL (group 1; 49±2%; p〈0.005; group 2: 51±3%, p〈0.01; control subjects 40±2%) (mean ± SEM) in relation to total VLDL. By contrast, the absolute lipid concentration of small VLDL was higher only in group 1, compared to control subjects (35±4 vs 27±3 mg/dl, p=0.05). Post-heparin hepatic lipase activity was significantly reduced in both IDDM groups (group 1: 254±19 mU/ ml, p〈0.05; group 2: 202±19 mU/ml, p〈0.005; control subjects 317±31 mU/ml). In conclusion, normolipidaemic IDDM patients show an increase in the smallest VLDL, whatever their degree of blood glucose control. However, this abnormality may be clinically relevant only in patients with unsatisfactory blood glucose control, since absolute lipid concentration of these potentially atherogenic particles is only increased in this group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400602
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  • 6
    Electronic Resource
    Electronic Resource
    Increased activity of the insulin-like growth factor system in mesangial cells cultured in high glucose conditions. Relation to glucose-enhanced extracellular matrix production (1996)
    Springer
    Diabetologia 39 (1996), S. 775-784 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Insulin-like growth factor-I ; II ; binding proteins ; receptors ; transforming growth factor-b ; extracellular matrix ; mesangial cell ; diabetes mellitus.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent evidence suggests that several growth factors participate in diabetic glomerular disease by mediating increased extracellular matrix accumulation and altered cell growth and turnover leading to mesangial expansion. Transforming growth factor (TGF)-β has been demonstrated to be upregulated both in vivo and in vitro, whereas studies on the activity of the renal insulin-like growth factor (IGF) system in experimental diabetes have provided conflicting results. We investigated the effects of prolonged exposure (4 weeks) of cultured human and rat mesangial cells to high (30 mmol/l) glucose vs iso-osmolar mannitol or normal (5.5 mmol/l) glucose levels on: 1) the autocrine/paracrine activity of the IGF system (as assessed by measuring IGF-I and II, IGF-I and II receptors, and IGF binding proteins); and, in parallel, on 2) TGF-β1 gene expression; 3) matrix production; and 4) cell proliferation. High glucose levels progressively increased the medium content of IGF-I and the mRNA levels for IGF-I and IGF-II, increased IGF-I and IGF-II binding and IGF-I receptor gene expression, and reduced IGF binding protein production. TGF-β1 transcripts and matrix accumulation and gene expression were increased in parallel, whereas cell proliferation was reduced. Iso-osmolar mannitol did not affect any of the above parameters. These experiments demonstrated that high glucose levels induce enhanced mesangial IGF activity, together with enhanced TGF-β1 gene expression, increased matrix production, and reduced cell proliferation. It is possible that IGFs participate in mediating diabetes-induced changes in matrix turnover leading to mesangial expansion, by acting in a paracrine/autocrine fashion within the glomerulus. [Diabetologia (1996) 39: 775–784]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250050510
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  • 7
    Electronic Resource
    Electronic Resource
    Regulatory role of eicosanoids in extracellular matrix overproduction induced by long-term exposure to high glucose in cultured rat mesangial cells (1996)
    Springer
    Diabetologia 39 (1996), S. 1055-1062 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Extracellular matrix ; transforming growth factor-β ; prostaglandins ; thromboxane ; mesangial cell ; diabetes mellitus.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Accumulation of extracellular matrix in the mesangium and altered renal eicosanoid synthesis are two prominent features of diabetic glomerular disease. We investigated the relationship between eicosanoid and extracellular matrix production in rat mesangial cells cultured under high glucose vs normal glucose conditions. Long-term exposure of rat mesangial cells to high glucose, but not to iso-osmolar mannitol, significantly increased extracellular matrix accumulation and gene expression and transforming growth factor-β (TGF-β) mRNA levels, and decreased prostaglandin (PG) E2 synthesis without affecting production of either thromboxane (TX) B2 or PGF2 a, with respect to cells incubated in normal glucose. Addition of exogenous PGE2 resulted in a dose-dependent reduction of matrix protein and mRNA levels and TGF-β gene expression in cells cultured in either normal or high glucose conditions, whereas exposure to exogenous PGF2α produced a significant increment in matrix production and matrix and TGF-β gene expression in cells grown in normal glucose, but only a slight increase in those cultured in high glucose. Stimulation of endogenous endoperoxide metabolism towards PGE2 and PGF2α synthesis with FCE-22,178, a drug originally developed as TXA2 synthase inhibitor, resulted in a dose-dependent decrease in matrix accumulation and matrix and TGF-β gene expression which was suppressed by co-incubation with the cyclo-oxygenase inhibitor fenoprofen blocking the FCE-22,178-enhanced PG production. In both cell lines, the rate of synthesis of TXA2 was very low and the selective blockade of its synthesis (by two other TXA2 synthase inhibitors, OKY-046 and Ridogrel) or action (by the TXA2 receptor antagonist BM-13,177) did not alter matrix production or TGF-β mRNA levels. These results suggest that the cyclo-oxygenase pathway is involved in the regulation of matrix changes induced by high glucose in rat mesangial cells; the reduced production of PGE2 may enhance the synthesis or potentiate the effect of stimulators of ECM formation such as TGF-β, whereas TXA2 does not appear to be involved. These data also indicate that glucose-enhanced mesangial matrix accumulation may be prevented by exogenous PGE2 or by drugs capable of increasing endogenous PGE2 synthesis. [Diabetologia (1996) 39: 1055–1062]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400654
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  • 8
    Electronic Resource
    Electronic Resource
    Regulatory role of eicosanoids in extracellular matrix overproduction induced by long-term exposure to high glucose in cultured rat mesangial cells (1996)
    Springer
    Diabetologia 39 (1996), S. 1055-1062 
    Details
    ISSN: 1432-0428
    Keywords: Extracellular matrix ; transforming growth factor-Β ; prostaglandins ; thromboxane ; mesangial cell ; diabetes mellitus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Accumulation of extracellular matrix in the mesangium and altered renal eicosanoid synthesis are two prominent features of diabetic glomerular disease. We investigated the relationship between eicosanoid and extracellular matrix production in rat mesangial cells cultured under high glucose vs normal glucose conditions. Long-term exposure of rat mesangial cells to high glucose, but not to iso-osmolar mannitol, significantly increased extracellular matrix accumulation and gene expression and transforming growth factor-Β (TGF-Β) mRNA levels, and decreased prostaglandin (PG) E2 synthesis without affecting production of either thromboxane (TX) B2 or PGF2α, with respect to cells incubated in normal glucose. Addition of exogenous PGE2 resulted in a dose-dependent reduction of matrix protein and mRNA levels and TGF-Β gene expression in cells cultured in either normal or high glucose conditions, whereas exposure to exogenous PGF2α produced a significant increment in matrix production and matrix and TGF-Β gene expression in cells grown in normal glucose, but only a slight increase in those cultured in high glucose. Stimulation of endogenous endoperoxide metabolism towards PGE2 and PGF2α synthesis with FCE-22,178, a drug originally developed as TXA2 synthase inhibitor, resulted in a dose-dependent decrease in matrix accumulation and matrix and TGF-Β gene expression which was suppressed by co-incubation with the cyclo-oxygenase inhibitor feno-profen blocking the FCE-22,178-enhanced PG production. In both cell lines, the rate of synthesis of TXA2 was very low and the selective blockade of its synthesis (by two other TXA2 synthase inhibitors, OKY-046 and Ridogrel) or action (by the TXA2 receptor antagonist BM-13,177) did not alter matrix production or TGF-Β mRNA levels. These results suggest that the cyclo-oxygenase pathway is involved in the regulation of matrix changes induced by high glucose in rat mesangial cells; the reduced production of PGE2 may enhance the synthesis or potentiate the effect of stimulators of ECM formation such as TGF-Β, whereas TXA2 does not appear to be involved. These data also indicate that glucose-enhanced mesangial matrix accumulation may be prevented by exogenous PGE2 or by drugs capable of increasing endogenous PGE2 synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400654
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of dietary cholesterol on plasma lipoproteins and their subclasses in IDDM patients (1998)
    Springer
    Diabetologia 41 (1998), S. 193-200 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Dietary cholesterol ; plasma lipoproteins ; lipoprotein subclasses ; lipoprotein composition ; IDDM patients.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To compare the effects of dietary cholesterol supplementation in insulin-dependent diabetic (IDDM) patients and normal subjects, 10 male IDDM patients in good glycaemic control (HbA1 c 7.3 ± 0.9 %) (mean ± SD) and normal plasma lipid levels, and 11 control male subjects of similar age, body mass index and lipid plasma levels underwent a double blind, cross-over, sequential study. Cholesterol supplementation of 800 mg/day or placebo were given for consecutive periods of 3 weeks. The concentration of plasma total cholesterol increased significantly with the dietary cholesterol supplementation compared to placebo in IDDM patients by 6 % (p 〈 0.05) and in control subjects by 9 % (p 〈 0.05). No changes were observed in the concentration of plasma triglycerides in either group. The LDL cholesterol level increased by 12 % (p 〈 0.01) in patients and by 7 % (p 〈 0.05) in control subjects. In patients plasma HDL cholesterol concentration remained the same, while in control subjects it tended to increase after cholesterol supplementation (from 1.14 ± 0.26 to 1.23 ± 0.27 mmol/l, p = 0.06). During the cholesterol intake period the mean concentration of LDL1, LDL2 and LDL3 subclasses in patients showed a significant increase by 21.0 (p 〈 0.05), 20.4 (p 〈 0.001) and 11.1 % (p 〈 0.05), respectively, resulting in an 18.0 % increase in mean total LDL mass (p 〈 0.001) without major changes in LDL composition. In the control subjects the changes in the concentrations of LDL subclasses during cholesterol intake were less and not significant. In the IDDM patients the cholesterol intake did not affect the concentration or composition of HDL subclasses or total HDL mass. In contrast, in control subjects cholesterol intake increased the mean concentration of HDL2 a by 12.2.% (p 〈 0.05) and this increase was significantly different if compared to changes obtained in the patients. In conclusion, compared to normal subjects, in IDDM patients, dietary cholesterol intake increased the LDL particle mass significantly and had no positive effect on HDL. [Diabetologia (1998) 41: 193–200]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250050889
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  • 10
    Electronic Resource
    Electronic Resource
    CT and anal endosonography in the evaluation of electrically stimulated neoanal sphincter: a preliminary report (1996)
    Springer
    Abdominal imaging 21 (1996), S. 353-356 
    Details
    ISSN: 1432-0509
    Keywords: Key words: Fecal incontinence—Gracilis muscle transposition—Computed tomography—Anal endosonography.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We report a preliminary experience concerning the postoperative assessment of three patients who underwent gracilis neosphincter operation for severe fecal incontinence and were studied by computed tomography and anal endosonography soon after gracilis transposition and later after 6–8 weeks of neuromuscular training. Morphologic assessment was correlated with physiologic testing (manometry). Continence was satisfactorily improved in all patients. Both imaging techniques demonstrated the anatomy of the transposed muscle. Computed tomography also assessed lead placement onto the gracilis nerve root and the completeness of muscle transposition around the anal canal. Anal endosonography provided a more accurate assessment of the relation between the neosphincter and residual external sphincter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002619900080
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