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  • 1995-1999  (4)
  • 1985-1989
  • 1940-1944
  • 1930-1934
  • 1996  (4)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 8 (1996), S. 2678-2691 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Scalar mixing models are required to model turbulent molecular mixing in full probability density function (pdf) simulations of turbulent reacting flows. Despite the existence of direct numerical simulation (DNS) data suggesting the contrary, most scalar mixing models assume that molecular mixing is independent of the instantaneous velocity, i.e., 〈D∇2φ|V,ψ〉=〈D∇2φ|ψ〉. Since in a joint velocity, composition pdf calculation the velocity is known, this assumption is unnecessary and leads to a lack of local isotropy in the scalar field. Moreover, since velocity conditioning offers a numerically tractable approach for including the effects of local anisotropy and mean velocity gradients on scalar mixing, it should be of considerable interest for the numerical simulation of scalar mixing in inhomogeneous turbulent flows. An efficient numerical implementation of velocity-conditioned scalar mixing for full pdf simulations is proposed and verified against DNS data for homogeneous turbulence (isotropic and shear flow) with a uniform mean scalar gradient. A second-moment closure relating the velocity-conditioned scalar dissipation to the scalar fluxes and Reynolds stresses that is exact in the limit of a joint Gaussian pdf is also derived for use with moment closure models. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 51 (1996), S. 0 
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Twenty children (six female), median age 24 months (range 12–156) who presented for application of a plaster jacket for scoliosis were studied pre-operatively with pulse oximetry overnight and on the first postoperative night. Pre-operatively the median (range) arterial oxygen saturation was 97 (95–98)%, although eight children had short episodes of desaturation to 〈90%. Postoperatively the median saturation was unchanged, and nine children had short episodes of desaturation. Neither the presence of episodes of desaturation pre-operatively, nor the median or lowest saturation recorded were predictors of postoperative median saturation or the presence of episodes of desaturation. Despite the presumed reduction in chest wall compliance, the application of a plaster jacket for scoliosis in these young children was not associated with a significant change in their oxygenation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 781 (1996), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Myelographie ; Postpunktionelles Syndrom ; Nadelspitze ; Iotrolan ; Key words Myelography ; adverse effects ; Iotrolan ; Spinal puncture instrumentation ; Needle-stick injuries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Purpose: Myelography in combination with a postmyelography CT is an important presurgical examination because of its excellent visualisation of the disc, the bone and the contrast-filled dura. Side effects after myelography can be observed in up to 50 % of patients. The pathophysiological mechanism is thought to be increased cerebrospinal fluid leakage at the puncture site. Since the introduction by Sprotte in 1979 of the pencil-point needle, a modification of Whitacre's needle, fewer complaints after lumbar puncture have been reported. The aim of the study was to examine the influence of two types of needle points and the temperature (37 °C vs 21 °C) of the contrast medium (CM; iotrolan, Isovist) on the incidence of side effects of lumbar puncture for myelography. Material and methods: In a prospective randomized trial the incidence of complaints after lumbar puncture with intrathecal CM application was evaluated by the use of a 21-G pencil-point needle as modified by Sprotte compared to our usual 22-G needle with a Quincke bevel. Some 412 patients (201 female, 211 male; mean age 54.05 ± 7.4 years) were investigated. Directly after examination and 1, 3 and 5 days later the patients were questioned about complaints (headache, neck stiffness nausea, vomiting, buzzing in the ear and dizziness). The results were tested by the chi square test. Results: A significantly lower incidence of complaints was seen after lumbar puncture with the pencil-point needle/Quincke needle (headache: 6.3 %/18.9 %, P 〈 0.0001; headache lasting 3 days: 0.5 %/7.8 %, P 〈 0.0001; headache lasting 5 days: 0 %/2.4 %, P = 0.0305; nausea: 0 %/4.9 %, P = 0.0009; vomiting: 0 %/4.9 %, P = 0.0009; dizziness: 0 %/3.4 %, P = 0.0074; neck stiffness: 0 %/3.4 %, P = 0.0074). The temperature of the CM had no influence on the complaints. No influence was seen on the quality of the myelogram. No relation to sex and age was found. Conclusion: Complaints after lumbar puncture and myelography are caused by the cerebrospinal fluid leakage at the puncture site. The incidence of side effects related to this leakage can be reduced by using a pencil-point needle. The temperature of the CM has no influence on the complaints.
    Notes: Zusammenfassung Die Myelographie zusammen mit der Postmyelographie-CT ist eine wichtige Untersuchungsmethode in der präoperativen Diagnostik. Bei nahezu der Hälfte der Patienten können postpunktionelle Beschwerden bis zu einem Postmyelographie-Syndrom (PMS) auftreten. Pathophysiologisch kann dies durch ein Punktionsleck mit anschließendem Liquorverlust erklärt werden. Ziel der Studie ist es, den Einfluß zweier Nadeltypen (21 G Nadel nach Sprotte vs 22 G Nadel nach Quincke) auf die Inzidenz postpunktioneller Beschwerden zu überprüfen. In einer prospektiven randomisierten Studie wurden bei 412 Patienten nach lumbaler intrathekaler Kontrastmittelapplikation (Iotrolan, Fa. Schering) die Häufigkeit des PMS und postpunktioneller Nebenwirkungen in Abhängigkeit vom verwendeten Nadeltyp untersucht. Die Häufigkeit postpunktioneller Beschwerden nach lumbaler Punktion mit der bleistiftförmigen Nadel nach Sprotte im Vergleich zur geschliffenen Nadel nach Quincke lag deutlich niedriger (Kopfschmerzen: 6,3 % vs 18,9 %, p 〈 0,0001; Kofschmerzen für mindestens drei Tage: 0,5 % vs 7,8 %, p 〈 0,0001; Kopfschmerzen für mindestens 5 Tage: 0 % vs 2,4 %, p = 0,0305; Übelkeit: 0 % vs 4,9 %, p = 0,0009; Erbrechen: 0 % vs 4,9 %, p = 0,0009; Schwindel: 0 % vs 3,4 %, p = 0,0074; Nackensteife: 0 % vs 3,4 %, p = 0,0074; PMS: 0 % vs 3,4 %, p = 0,0074). Die Temperatur des Kontrastmittels beeinflußte die postmyelographischen Beschwerden nicht. Schlußfolgerung: Die Inzidenz des PMS und postpunktioneller Beschwerden kann durch den Einsatz einer „atraumatischen“Nadel nach Sprotte deutlich gesenkt werden.
    Type of Medium: Electronic Resource
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