ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Experimental data of the radial incorporation of labeled cholesterol [14C-4] into the artery wall is regressed against a mathematical model that predicts macromolecular transport in this biological system. Data is obtained using excised canine carotid arteries that are perfusedin vitro under pulsatile hemodynamic conditions for 2 hr. Vessels are exposed to either normotensive hemodynamics, hypertensive hemodynamics, or simulations in which the rate of flow or vessel compliance is deliberately altered. Several arteries are studied under normotensive conditions following balloon catheter deendothelialization. Transmural concentration profiles of [14C-4] activity are determined by microcryotomy of longitudinal sections of perfused vessels. Nonlinear Marquardt regression on 12 experimental cases yields parameter estimates of effective diffusivity,D and solute filtration velocity,V. Results of this experimental investigation support our hypothesis that hemodynamics and the endothelial lining influence wall flux in intact vessels. Exposure to altered (vs normotensive) hemodynamics is associated with increased incorporation of labeled cholesterol. A similar observation is made for deendothelialized vessels (e.g. a greater accumulation of label and a rise in convective flux). Based upon our companion measurements of vessel wall forces and endothelial cellular morphology accompanying hemodynamic simulations, we suggest that hemodynamically induced alterations to endothelial structures lead to the increased permeability, convection and incorporation that we observe in this work.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Mineralium deposita 3 (1968), S. 1-17 
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Die Notwendigkeit, Exploration zu treiben, ergibt sich aus der Tatsache, daß sich die Tonnage des Fördergutes im Bergbau alle zwölf Jahre verdoppelt. Die Abhängigkeit der Explorationskosten vom Profit und Kapitalfluß wird aufgezeigt. Tabelle 1 und 2 stellen die Kapitalauslagen für ausgewählte Grubenbetriebe in den U.S. und in Canada dar. Das zunehmende Explorationsrisiko, d. h. die Ausgaben pro Entdeckung, verlangt die Entwicklung von Kriterien zur Beurteilung von Explorationsprojekten auf einer Erfolgsaussichts-Basis, die den Zufall (Chance), daß das Vorkommen vorhanden ist, daß es auch wirklich entdeckt wird und daß es genügend abbauwürdig ist, einschließen. Diese Faktoren werden erörtert und ihre Ermittlung und Beurteilung wird erläutert. Es ergibt sich eine praktische Gleichung, mit der der Gewinn eines und einer Serie von Explorationswagnissen ermittelt und den negativen Faktoren gegenübergestellt wird. Es besteht somit die Möglichkeit, Explorationsprojekte im voraus zu beurteilen.
    Notes: Abstract The need for exploration and discovery is apparent from the doubling of tonnage mined about each 12 years. The dependency of exploration expenditure on profits and cash flow is indicated. The capital outlays for selected U.S. and Canadian mines are listed, Tables 1 and 2. The increasing exploration risk, i.e., money spent per discovery, necessitates that criteria be evolved to evaluate exploration projects on the basis of their profitability potential. This involves the chance of occurrence, the chance of actual discovery and the chance of sufficient economic value. These factors are discussed and their evaluation is outlined. An operational equation is set up, and the return on an exploration venture, and a series of exploration ventures, versus the odds against involved, are presented as a possible means of pre-evaluating exploration projects.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...