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  • 1
    Electronic Resource
    Electronic Resource
    Using cavitation to measure statistics of low-pressure events in large-Reynolds-number turbulence (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 12 (2000), S. 1485-1496 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure of the pressure field of a turbulent water flow between counter-rotating disks is studied using cavitation. The flow is seeded with microscopic gas bubbles and the hydrostatic pressure is reduced until large negative pressure fluctuations trigger cavitation. Cavitation is detected via light scattering from cavitating bubbles. The spatial structure of the low-pressure events are visualized using a high-speed video system. A fast photo detector is used to measure the scaling of the cavitation statistics with the pressure. This data is used to determine the shape of the tail of the probability density function for the pressure. The tail is found to be exponential and scales more rapidly with Reynolds number than the standard deviation of the pressure. This may indicate the influence of internal intermittency. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.870397
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  • 2
    Electronic Resource
    Electronic Resource
    Spectral Analysis of RR and R-T Variabilities in Patients with Coronary Artery Disease (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of noninvasive electrocardiology 3 (1998), S. 0 
    Details
    ISSN: 1542-474X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: As the duration of the Q-T interval is dependent upon the length of the preceding cardiac cycle, changes in QT interval duration mainly reflect, in normal subjects, the physiological beat-by-beat variability of the sinus node. However, little information is available on short-term Q-T variability in patients with an abnormal neural modulation of the sinus node.Methods: We analyzed, with autoregressive techniques, RR and R-Tapex, and R-Tend variabilities in 12 patients after myocardial infarction, in 13 patients before and after percutaneous transluminal coronary angioplasty (PTCA), and in 10 age-matched controls.Results: No significant differences in mean value and variance of RR, R-Tapex, and R-Tend interval among the three groups of subjects were observed. Spectral analysis of RR variability was characterized by signs of sympathetic activation with a predominance of low frequency (LF) component in patients after myocardial infarction (69 ± 5 nu) and before PICA (74 ± 5 nu) in comparison to controls (50 ± 4 nu). Instead, spectral energy was equally distributed within LF and HF (high frequency) components of RTapex and R-Tend variabilities in the three groups of subjects.Conclusions: These data indicate that the predominance of LFRR in normalized units, indicating an increase of sympathetic modulation of sinus node activity in patients with coronary artery disease, are not accompanied by a parallel predominance of the LF component of R-Tapex and R-Tend variabilities. This difference reflects, in our opinion, a minor dependency of duration of ventricular repolarization from the preceding cardiac cycle in patients with coronary artery disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1542-474X.1998.tb00349.x
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  • 3
    Electronic Resource
    Electronic Resource
    Low and High Frequency Components of Blood Pressure Variability (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 783 (1996), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1996.tb26704.x
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  • 4
    Electronic Resource
    Electronic Resource
    Fluid particle accelerations in fully developed turbulence (2001)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 409 (2001), S. 1017-1019 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The motion of fluid particles as they are pushed along erratic trajectories by fluctuating pressure gradients is fundamental to transport and mixing in turbulence. It is essential in cloud formation and atmospheric transport, processes in stirred chemical reactors and combustion systems, and in ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35059027
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  • 5
    Electronic Resource
    Electronic Resource
    An inorganic coating process providing copper with an electrically insulating layer by anodisation in non-aqueous fluoride electrolytes
    Amsterdam : Elsevier
    Electrodeposition and Surface Treatments 1 (1973), S. 253-265 
    Details
    ISSN: 0300-9416
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0300-9416(73)90018-7
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  • 6
    Electronic Resource
    Electronic Resource
    Conditional entropy approach for the evaluation of the coupling strength (1999)
    Springer
    Biological cybernetics 81 (1999), S. 119-129 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract. A method that enables measurement of the degree of coupling between two signals is presented. The method is based on the definition of an uncoupling function calculating, by means of entropy rates, the minimum amount of independent information (i.e. the information carried by one signal which cannot be derived from the other). An estimator of the uncoupling function able to deal with short segments of data (a few hundred samples) is proposed, thus enabling the method to be used for usual experimental recordings. A synchronisation index is derived from the estimate of the uncoupling function by means of a minimisation procedure. It quantifies the maximum amount of information exchanged between the two signals. Simulations in which non-linear coordination schemes are produced and changes in the coupling strength are artificially induced are used to check the ability of the proposed index to measure the degree of synchronisation between signals. The synchronisation analysis is utilised to measure the coupling strength between the beat-to-beat variability of the sympathetic discharge and ventilation in decerebrate artificially ventilated cats and the degree of synchronisation between the beat-to-beat variability of the heart period and ventricular repolarisation interval in normal subjects and myocardial infarction patients. The sympathetic discharge and ventilation are strongly coupled and the coupling strength is not affected by manoeuvres capable of increasing or depressing sympathetic activity. The synchronisation is lost after spinalisation. The synchronisation analysis confirms that the heart period and ventricular repolarisation interval are well coordinated. In normal subjects, the synchronisation index is not modified by experimental conditions inducing changes in the sympathovagal balance. On the contrary, it strongly decreases after myocardial infarction, thus detecting and measuring the uncoupling between the heart period and ventricular repolarisation interval.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004220050549
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  • 7
    Electronic Resource
    Electronic Resource
    Classification of coupling patterns among spontaneous rhythms and ventilation in the sympathetic discharge of decerebrate cats (1996)
    Springer
    Biological cybernetics 75 (1996), S. 163-172 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract.  The spontaneous low- and high-frequency rhythms in the sympathetic discharge of decerebrate artificially ventilated cats are affected by external ventilation. Two graphical methods (i.e. the space-time separation plot and the frequency tracking locus) are used to classify the non-linear interactions. The observed behaviours in the sympathetic discharge consist of phase-locked periodic dynamics (at various frequency ratios with ventilation), quasiperiodic and aperiodic patterns. They depend on the experimental condition. In control condition the sympathetic discharge appears more frequently locked to each ventilatory cycle (1 : 1 dynamics). However, some cases of quasiperiodic dynamics are found. A sympathetic activation stimulus, such as inferior vena cava occlusion, is able to synchronise slow rhythms in the sympathetic discharge to a subharmonic of ventilation. During a sympathetic inhibition stimulus, such as aortic constriction, 1 : 1 dynamics is detected but the amplitude of the sympathetic responses can be modulated by unlocked slow rhythms. Moreover, some cases of aperiodic dynamics are observed. Vagotomy reduces the 1 : 1 coupling between sympathetic outflow and ventilation. Vagotomy plus spinalisation disrupts periodic dynamics in the sympathetic discharge so that irregular and complex patterns are found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004220050284
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  • 8
    Electronic Resource
    Electronic Resource
    Measuring regularity by means of a corrected conditional entropy in sympathetic outflow (1998)
    Springer
    Biological cybernetics 78 (1998), S. 71-78 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract. A new method for measuring the regularity of a process over short data sequences is reported. This method is based on the definition of a new function (the corrected conditional entropy) and on the extraction of its minimum. This value is taken as an index in the information domain quantifying the regularity of the process. The corrected conditional entropy is designed to decrease in relation to the regularity of the process (like other estimates of the entropy rate), but it is able to increase when no robust statistic can be performed as a result of a limited amount of available samples. As a consequence of the minimisation procedure, the proposed index is obtained without an a-priori definition of the pattern length (i.e. of the embedding dimension of the reconstructed phase space). The method is validated on simulations and applied to beat- to-beat sequences of the sympathetic discharge obtained from decerebrate artificially ventilated cats. At control, regular, both quasiperiodic and periodic (locked to ventilation) dynamics are observed. During the sympathetic activation induced by inferior vena cava occlusion, the presence of phase-locked patterns and the increase in regularity of the sympathetic discharge evidence an augmented coupling between the sympathetic discharge and ventilation. The reduction of complexity of the neural control obtained by spinalization decreases the regularity in the sympathetic outflow, thus pointing to a weaker coupling between the sympathetic discharge and ventilation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004220050414
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  • 9
    Electronic Resource
    Electronic Resource
    Pathotyping isolates of Newcastle disease virus using antipeptide antibodies to pathotype-specific regions of their fusion and hemagglutinin-neuraminidase proteins (1999)
    Springer
    Archives of virology 144 (1999), S. 55-72 
    Details
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary.  Antipeptide antibodies have been evaluated for their abilities to predict the characteristics of the cleavage motifs of the fusion protein precursors (F0) of 25 isolates of Newcastle disease virus (NDV) with a range of virulences, grouped into 12 sets according to their monoclonal antibody reactivities. A Western blot format was used to show that antisera to synthetic peptides representing sequences at the C-termini of the F2-polypeptides of defined pathotypes of NDV usually distinguish between pathotypes on the basis of their Fo cleavage sequences. However, exceptions were found with three groups of virulent isolates. Protein sequencing and mass spectral analysis of the F2-polypeptide of isolate Texas GB from one of these groups, identified an anomalous cleavage/activation process which removed the amino acids required for recognition by the antisera. This probably also explained the lack of reactivity of the Roakin isolate and low reactivity of the Komarov isolate from this group. The other exceptions involved isolates in groups with cleavage region variations from the usual motif of virulent isolates or isolates with undefined cleavage motifs. Antipeptide antisera were also raised to sections of the 45 residue C-terminal extension the hemagglutinin-neuraminidase precursor (HN0) encoded by the genes of some avirulent isolates. Western blot analysis showed that positive reactions with antibodies to peptides based on sequences between residues 577 and 613 of the HN0 was evidence for the presence of an avirulent isolate but did not exclude the presence of other pathotypes. Antisera designed to target residues 569–577 detected HN0 extensions of 6 residues on isolates known to encode such extensions. These antisera also enabled differentiation of isolates with HN0 extensions of 6 residues from those with no extension, however, it was not possible to determine the virulence of isolates based on reaction with these antisera.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007050050485
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  • 10
    Electronic Resource
    Electronic Resource
    Lipoprotein(a) levels and apolipoprotein(a) polymorphism in type 1 diabetes mellitus: relationships to microvascular and neurological complications (1998)
    Springer
    Acta diabetologica 35 (1998), S. 13-18 
    Details
    ISSN: 1432-5233
    Keywords: Key words Lipoprotein(a) ; Apolipoprotein(a) polymorphism ; Insulin-dependent diabetes mellitus ; Microangiopathy ; Neuropathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To investigate plasma concentrations of lipoprotein(a) [Lp(a)] and apolipoprotein(a) [apo(a)] polymorphism in relation to the presence of microvascular and neurological complications in type 1 diabetes mellitus, 118 young diabetic patients and 127 age-matched controls were recruited. Lp(a) levels were higher in patients than in controls, but the apo(a) isoforms distribution did not differ between the two groups [higher prevalence of isoforms of high relative molecular mass (RMM) in both groups]. Microalbuminuric patients had Lp(a) levels significantly greater than normoalbuminuric patients, and normoalbuminuric patients showed higher Lp(a) levels than controls. Patients with retinopathy or neuropathy showed similar Lp(a) levels to those without retinopathy or neuropathy. No differences in apo(a) isoforms frequencies were observed between subgroups with and without complications (higher prevalence of isoforms of high RMM in every subgroup). However, among patients with retinopathy, those with proliferative retinopathy had higher Lp(a) levels and a different apo(a) isoforms distribution (higher prevalence of isoforms of low RMM) than those with non-proliferative and background retinopathy (higher prevalence of isoforms of high RMM). Our data suggest that young type 1 diabetic patients without microalbuminuria have Lp(a) levels higher than healthy subjects of the same age. Lp(a) levels are further increased in microalbuminuric patients. High Lp(a) levels and apo(a) isoforms of low RMM seem to be associated with the presence of proliferative retinopathy, but have no relation to neuropathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005920050095
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