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  • 1
    Electronic Resource
    Electronic Resource
    ELECTROPHORETIC ISOLATION OF CONSTITUENTS OF RAGWEED POLLEN EXTRACTS* (1940)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 62 (1940), S. 1627-1627 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01863a513
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  • 2
    Electronic Resource
    Electronic Resource
    The source and action of histamine in the isolated guinea-pig gallbladder (1995)
    Springer
    Inflammation research 44 (1995), S. 447-453 
    Details
    ISSN: 1420-908X
    Keywords: Gallbladder ; Histamine ; Mast cells ; Contraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have investigated the effects of histamine on motility of the gallbladder and characterized the receptor types involved. Histamine and the histamine H1-receptor agonist, 2-thiazolylethylamine (2-TEA) contracted the isolated guinea-pig gallbladder strip in a dose dependent manner. The contractile response to histamine was shifted to the right by the H1-receptor antagonist, mepyramine. In pre-contracted gallbladder strips, the H2-receptor agonist dimaprit reduced the tension generated in a dose dependent fashion. The histamine H2-receptor antagonist, ranitidine shifted the histamine concentration effect curve to the left and attenuated the dose dependent relaxations elicited at high concentrations. The histamine H3-receptor agonist, (R)-α-methylhistamine (RMHA) elicited dose dependent contraction of the tissue which was significantly inhibited in the presence of mepyramine. The effects of electrical field stimulation (EFS) on the strips were not significantly altered by the presence of RMHA (10−10−10−7 M) indicating little pre-synaptic H3 activity in this tissue. Histamine immunoreactivity (IR) was detected in gallbladder whole mount preparations of the mucosa and the muscularis/serosa. The histamine IR appeared cell bound in cells of varying morphological characteristics but no IR was detected in nerve fibres or cell bodies (ganglia). Alcian blue staining was consistent with the distribution of histamine IR cells as mast cells. The results indicate that histamine is distributed in the guinea-pig gallbladder and it can regulate contractile activity via activation of H1 and H2 but not H3 receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01757702
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  • 3
    Electronic Resource
    Electronic Resource
    Integrin-mediated signal transduction (1998)
    Springer
    Cellular and molecular life sciences 54 (1998), S. 514-526 
    Details
    ISSN: 1420-9071
    Keywords: Key words. Integrin; cell adhesion; extracellular matrix; signalling; focal adhesion kinase.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Integrins, expressed on virtually every cell type, are proteins that mediate cellular interactions with components of the extracellular matrix (ECM) and cell surface integral plasma membrane proteins. In addition, integrins interact with the cytoskeleton and through this process participate in cell migration, tissue organization, cell growth, haemostasis, inflammation, target recognition of lymphocytes and the differentiation of many cell types. Signals generated from ligand-integrin interactions are propagated via the integrin cytoplasmic tails to signal transduction pathways within the cell (outside-in signalling). Information from within the cell can also be transmitted to the outside via integrin affinity modulation (inside-out signalling). Protein tyrosine phosphorylation has a central role in integrin-initiated cell signalling, leading to cytoskeletal organization and focal adhesion formation. This review will examine the current understanding of integrin function, focusing on the intracellular consequences of integrin-ligand interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000180050180
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  • 4
    Electronic Resource
    Electronic Resource
    A direct error analysis for least squares (1974)
    Springer
    Numerische Mathematik 22 (1974), S. 325-332 
    Details
    ISSN: 0945-3245
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A direct error analysis is given for orthogonal factorization methods for calculating the least squares solution of an overdetermined system of linear equations. The direct method has the interesting advantage in that it permits the separation of errors occurring in the transformation and back-substitution phases of solution. This shows the partial elimination of potentially significant terms occurring in different stages of the algorithm. Presumably it is prudent to minimize the error at each stage of the algorithm, so it is significant that numerical evidence shows column pivoting can reduce the magnitude of these terms. This is offered as an explanation for the common observation that column pivoting is beneficial in least squares calculations. We also summarize the corresponding error analysis for the calculation of the minimum norm solution of an underdetermined system using orthogonal transformations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01406971
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  • 5
    Electronic Resource
    Electronic Resource
    Simple estimates of the thermal diffuse scattering contribution to Bragg peaks (1970)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 26 (1970), S. 613-622 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The thermal diffuse scattering (TDS) contribution to X-ray Bragg peaks is discussed in terms of its two experimental components, the included and the background parts. The discussion is primarily directed toward situations where detailed elastic constant information and a large computer are not available. Graphs are displayed which, in the spherical average approximation, allow an accurate assessment of the influence of all the experimental variables on the TDS contribution. It is shown that, even in the general case where spherical averaging is a poor approximation, the included TDS varies linearly with length of scan for small scans. A technique for determining the constant of proportionality is suggested. Thus the included TDS may be evaluated even though the elastic constants are not known.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739470001559
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  • 6
    Electronic Resource
    Electronic Resource
    Current status of the IUCr powder intensity project (1969)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 25 (1969), S. 217-222 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The eventual objective of powder intensity measurements, in the present context, is to obtain absolute integrated Bragg intensities from specimens which are ideal with respect to all parameters such as extinction, preferred orientation, etc. At present, the Project has been limited to a comparison of X-ray techniques on a number of samples of carbonyl process nickel which are known to be non-ideal, but which were determined by actual measurement to yield identical integrated intensities using Cu Kα radiation. Eleven samples have been measured in ten laboratories and six of these have been standardized by measurement of the incident beam. The results show that integrated intensities may not be relied on to better than 5%, even on a relative basis. It appears that, at the present time, the techniques for making an accurate measurement of the incident beam may be more reliable than those for measuring relative intensities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739469000374
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  • 7
    Electronic Resource
    Electronic Resource
    Polarization of crystal monochromated X-rays (1968)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 24 (1968), S. 472-474 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The polarization ratio in a bent crystal monochromated X-ray beam has been measured by examining the scattering at 90° in two orthogonal planes. The value was found only not to be far removed from the value expected on the basis of an ideally mosaic monochromator, but not even to lie between this value and that expected on the basis of an ideally perfect monochromator. This result has the implication that the polarization factor lies outside the range usually assumed possible. An explanation of this result in terms of large secondary extinction is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739468000951
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  • 8
    Electronic Resource
    Electronic Resource
    The polarization ratio of crystal monochromators (1984)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 40 (1984), S. 12-16 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A tabulation of some 40 measured values of the polarization ratio K (a measure of the fractional polarization introduced into an X-ray beam by a crystal monochromator) is presented. The values may be represented through the parameter n given by K = cosn2θM. The measured values of n cluster around unity and the theoretical rationale for this result is discussed. Possible explanations of outlying values are considered. A recommendation is made that the polarization ratio of an apparatus be measured using a direct method whenever possible, but methods for estimating a value of K are also given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767384000039
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  • 9
    Electronic Resource
    Electronic Resource
    International Union of Crystallography Commission on Crystallographic Apparatus. Accuracy of structure factors from X-ray powder intensity measurements (1977)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 33 (1977), S. 1012-1027 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The accuracy of the determination of the structure factors from a powder diffraction measurement is studied in light of a representative example: nickel with Cu Kα radiation. Various sources of error in the absolute measurement and methods of sample characterization are discussed. The contributions of various extraneous scattering mechanisms are assessed. From these considerations it is possible to separate the Bragg scattering, providing measurements are made through virtually the entire angular range. Results are given in detail for a standard sample, a duplicate of which can be made available to interested workers. The relationship of these results to the structure factors of the sample is discussed in terms of a model calculation, in terms of line shape analysis, and in terms of some comparative measurements on various samples of Ni and MgO. All these analyses indicate the impossibility of preparing a single sample which is ideally mosaic. Thus it is incorrect to relate the measured integrated reflection to the structure factor with the customary simple formula when high accuracy is required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739477002447
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  • 10
    Electronic Resource
    Electronic Resource
    Extinction, polarization and crystal monochromators (1981)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 37 (1981), S. 584-593 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A number of theories are examined for their predictions of extinction coefficients at large values of extinction, especially as applied to polarization ratios. Although several theories give the behavior expected on the basis of physical reasoning (a polarization ratio approaching unity), the popular theories of Zachariasen [Acta Cryst. (1967), 23, 558-564] and Becker & Coppens [Acta Cryst. (1964), A30, 129-147, 148-153] do not show the correct asymptotic behavior. Although this shortcoming may be of no consequence in ordinary crystallographic applications, it is misleading in predicting the correct polarization factor to be used in connection with a crystal-monochromated apparatus, where the monochromator is usually adjusted to maximize its extinction. The importance of measuring, rather than estimating, the polarization ratio of a crystal monochromator is therefore reemphasized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739481001320
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