Library

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
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 6477-6493 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In order to address the problem of three-body interactions in gas–surface scattering, we considered the collision of a He atom with the (0001) surface of graphite coated by a monolayer of Xe. To eliminate the uncertainties connected with errors in the two-body He–Xe interaction, we determined the latter by crossed-beam differential collision cross-section measurements performed at two energies (67.2 and 22.35 meV). These scattering data together with room-temperature bulk diffusion data are then fitted with a Hartree–Fock–dispersion–type function to yield an interaction potential that explains most of the properties of this system within the experimental errors and represents an improvement on previously published He–Xe potentials. Helium diffraction measurements are then carried out from the Xe overlayer and the dependence of the specular intensity from the angle of incidence is carefully determined. Further, a He–surface potential is constructed by adding together the following terms: (1) the He–Xe pairwise sum, (2) the long-range He–(0001)C interaction, (3) the three-body contribution generated by the Axilrod–Teller–Muto term, (4) the so-called surface-mediated three-body interaction He–Xe–(0001)C first considered by A. D. McLachlan [Mol. Phys. 7, 381 (1964)], and finally (5) a small correction which is meant to take into account the nonstationary nature of the surface. Using this potential, well-converged close-coupling scattering calculations are carried out, and their results compared with the data. In general, good agreement is obtained. The agreement can, however, be improved by (a) an increase of about 30% in the contribution of three-body forces, (b) the lowering of the He–graphite long-range attraction coefficient by about 15%, or (c) a reduction of the two-body interaction well depth of 1.6% (the experimental error) together with any combination of the factors under (a) and (b) reduced by an adequate amount. Elimination of the contribution of the graphite surface by studying Xe multilayers is hindered by the uncertainties in the "thermal correction'' [point (5) above] which, due to the multilayer increased "softness,'' becomes an appreciable source of uncertainty.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 28 (1987), S. 1844-1847 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: It is shown that Einstein's equations are always linearization stable around any finite region of space-time. Let (Ω,g0ab ) be any region of space-time, admitting a compact Cauchy surface with nonempty smooth boundary, and with g0ab a sufficiently smooth solution of the vacuum Einstein equation. It is shown that for any solution g1ab of the linearized equation and any open region U⊆Ω, there exists a smooth one-parameter family gλab of solutions on U such that (gλab||λ=0 =g0ab ) ||U and ((d/dλ)gλab =g1ab )||U. By using a result of Choquet-Bruhat and York [The Cauchy Problem, General Relativity and Gravitation, edited by A. Held (Plenum, New York, 1980), Vol. 1] asserting the smoothness of the map that sends initial data into solutions of Einstein's evolution equations the proof of the above theorem is reduced to the proof of a similar theorem for Einstein's constraint equations. The proof of this latter theorem involves the use of the implicit function theorem in Hilbert spaces. This local result on linearization stability asserts, in contrast to the general global case, that linearization about any vacuum solution is locally physically meaningful.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1436-6304
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1436-6304
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    OR spectrum 11 (1989), S. 191-195 
    ISSN: 1436-6304
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Summary The technique of designing and constructing simulation models is difficult and requires a lot of knowledge and experience. In general, users of simulation models don't have this expert knowledge. Up to now, it has not been possible to incorporate the expert knowledge necessary for the overall modelling within an expert system which would then in turn make the techniques accessible to the inexperienced user. In general, the close cooperation among experts in the fields of application and simulation techniques remains — for the time being — the only guarantee for successfully scrutinizing a model study. It is, however, possible to combine expert systems and simulation models when using carefully chosen, closely defined fields of application. It is here that an important area of interest and study lies. There are three conceivable alternatives: 1. To provide a simulation model with an intelligent environment which supports the user in constructing as well as evaluating the results made. 2. An expert system contains a simulation model as a possible component. If the expert system needs information that is not directly available, a simulation model is accessed which in turn sends the necessary data back to the expert system. 3. A simulation model contains an expert system as a component. In this case, the model has specific strategies at its disposal that are to be taken into consideration. If the model reaches a point where decisions have to be made, the simulation model turns to the expert system in order to receive information on relevant decisions. These relevant decisions are then used to determine the further course of the model. All three alternatives assume that the expert system as well as the simulation system have an open architecture. The open architecture is a prerequisite for the possibility of coupling the two. Up to now, this requirement has rarely been achieved.
    Notes: Zusammenfassung Der Entwurf und der Aufbau von Simulationsmodellen ist eine schwierige Technik, die sehr viel Wissen und Erfahrung voraussetzt. Die Anwender von Simulationsmodellen verfügen in der Regel über dieses Expertenwissen nicht. Bisher ist es nicht möglich, das für die Modellierung insgesamt erforderliche Expertenwissen in ein Expertensystem zu inkorporieren um es auf diese Weise dem in der Simulationstechnik unerfahrenen Anwender zugänglich zu machen. Im allgemeinen bleibt die enge Zusammenarbeit zwischen Fachleuten auf dem Anwendungsgebiet und der Simulationstechnik bis auf weiteres die einzige Garantie für eine erfolgreiche Modelluntersuchung. In ausgewählten, sehr engen abgegrenzten Anwendungsgebieten ist es jedoch möglich, Expertensysteme und Simulationsmodelle zu vereinen. Hier entwickelt sich ein bedeutendes Arbeits- und Aufgabenfeld. Es sind drei Alternativen vorstellbar: 1. Ein Simulationsmodell erhält eine intelligente Umgebung, die den Anwender beim Modellaufbau und bei der Ergebnisauswertung unterstützt. 2. Ein Expertensystem enthält als eine mögliche Komponente ein Simulationsmodell. Falls das Expertensystem Informationen benötigt, die nicht direkt verfügbar sind, wird ein Simulationsmodell angestoßen, das die erforderlichen Daten an das Expertensystem zurückliefert. 3. Ein Simulationsmodell enthält als Komponente ein Expertensystem. In diesem Fall enthält das Modell Strategien, die zu berücksichtigen sind. Falls das Modell an einen Punkt kommt, an dem Entscheidungen getroffen werden müssen, wendet sich das Simulationsmodell an das Expertensystem und läßt sich die maßgebenden, den weiteren Modellablauf bestimmenden Entscheidungen mitteilen. Alle drei Alternativen verlangen vom Expertensystem und dem Simulationssystem eine offene Architektur. Die offene Architektur ist Voraussetzung dafür, daß sich beide Systeme koppeln lassen. Diese Forderung ist bisher kaum erfüllt.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    facet.materialart.
    Unknown
    Berlin : Periodicals Archive Online (PAO)
    Deutsche Zeitschrift für Philosophie. 37:3 (1989) 257 
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 61 (1983), S. 165-167 
    ISSN: 1432-1440
    Keywords: Platelet-associated IgG ; Micro-enzyme-linked immunoassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An enzyme linked immunoassay was developed using the microtiter system to measure platelet-associated IgG (PAIgG). One single determination needs 2×106 platelets usually obtained from 3 ml blood anticoagulated with EDTA. Platelets are incubated with peroxidase-conjugated anti-human IgG. Its unbound fraction is adsorbed to an IgG coated microtiter plate, quantitated by a colour reaction and found to be inversely related to the amount of PAIgG. Healthy donors (n=40, aged 1 day to 35 years) possessed 3.6±2.0 (mean±S.D.) fg IgG/platelet. Increased levels of PAIgG were found in patients with acute (n=16) and chronic (n=5) idiopathic thrombocytopenic purpura. Postrecovery platelets had normal values of PAIgG. Widely varying levels of PAIgG were found in patients with freshly diagnosed acute lymphocytic leukemia.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Urological research 17 (1989), S. 41-42 
    ISSN: 1434-0879
    Keywords: Prostatic carcinoma ; Metastasis ; Zn concentration in plasma ; Hormone therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Zinc in serum of both patients with prostatic carcinoma and men without prostatic cancer was analyzed by flame atomic absorption spectrometry (FAAS). No significant differences were found between the group with prostatic carcinoma without metastasis and the group used for comparison. The Zn level in serum of patients with both prostatic carcinoma and metastases was decreased in comparison to the other groups. A decrease in the Zn concentration was also found for men without metastases after orchiectomy and hormone therapy.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 312 (1984), S. 150-152 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Figure 1 shows the areas from which the samples are derived. The deciduous oaks ( Quercus petraea and Quercus robur) used for both the German and Irish tree-ring studies show several marked differences from the bristlecone pines. They all grew at low altitude (〈200 m in Ireland and 400 m in ...
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Inflammation research 15 (1984), S. 34-35 
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...