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  • 1
    Electronic Resource
    Electronic Resource
    Effects of geometrical abberrations on intensities in powder diffractometry (1971)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 4 (1971), S. 37-43 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The effects of axial and equatorial divergences, of beam penetration, and of misalignment on the integrated Bragg reflections as well as on diffuse scattering and specimen fluorescence are calculated for the reflection and transmission methods of powder diffractometry. The formulation encompasses both the &thgr;0–2&thgr; case with stationary specimen and (wide) receiving slit and the usual &thgr;–2&thgr; scan with a narrow receiving slit. To a good approximation, the effects of the various aberrations may be separated and simple formulas which allow the corrections to be calculated to an accuracy of 0.1% are presented. Although almost all practical cases are included, the formulation is illustrated in detail for the important case of Bragg scattering in reflection geometry. The largest effects are in the low angle region where, for the &thgr;–2&thgr; scan, all the aberrations increase the observed intensity. For a realistic case of a low density sample near 20° 2&thgr;, the total correction may be well above 5%, but the results depend strongly on absorption coefficient and on scattering angle. The effects of the most serious aberrations are considerably reduced in the &thgr;0–2&thgr; case; for the above example the total is less than 2%. In the transmission method, within the useful range, the only significant aberrations arise from the deviation of the specimen center from the diffractometer axis and from axial divergences. In the case of diffuse scattering or specimen fluorescence, in either transmission or reflection geometries, the intensity is affected by the equatorial aberrations even more than in the Bragg case, but the effects of axial aberrations are usually negligible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889871006204
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  • 2
    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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  • 3
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    L'Amour-passion de Tristan à l'oeuvre proustienne: vicissitudes d'un mythe (1971)
    Syracuse, N.Y. : Periodicals Archive Online (PAO)
    Symposium. 25:2 (1971:Summer) 123 
    Details
    ISSN: 0039-7709
    Topics: Linguistics and Literary Studies
    Notes: MYTH
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:1222-1971-025-02-000002
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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Optimal control of singular systems with a cost on changing control (1996)
    Springer
    Dynamics and control 6 (1996), S. 63-89 
    Details
    ISSN: 1573-8450
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper, we consider a class of optimal control problems with a cost on changing control, where the system dynamics are described by singular differential equations. Using a constraint transcription coupled with a local smoothing technique, a penalty function, and the control parametrization technique, an efficient computational method is developed for solving this optimal control problem sequentially. The convergence performance of the proposed method is also established. For illustration, this method is used to find the optimal feeding policy for a fed-batch fermentation process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02169462
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  • 8
    Electronic Resource
    Electronic Resource
    Detection of Legionella DNA in Guinea Pig Peripheral Leukocytes, Urine and Plasma by the Polymerase Chain Reaction (1999)
    Springer
    European journal of clinical microbiology & infectious diseases 18 (1999), S. 445-447 
    Details
    ISSN: 1435-4373
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Legionella DNA has been detected in respiratory tract, serum and urine samples from patients with pneumonia by the polymerase chain reaction. A guinea pig model was used to assess whether Legionella DNA could also be detected in peripheral leukocytes during active infection. Ten guinea pigs were infected intraperitoneally with Legionella pneumophila serogroup 1, and leukocyte, plasma and urine samples were collected immediately before inoculation and on days 1, 3, 7 and 14 thereafter. All samples were tested for Legionella DNA by the polymerase chain reaction. Overall, Legionella DNA was detected in 55% of leukocyte samples, 28% of urine samples and 21% of plasma samples collected after inoculation. The sensitivity of the polymerase chain reaction on leukocytes was highest for samples collected within 3 days of inoculation. Further studies testing leukocyte samples from human Legionella infection are required to confirm these observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100960050316
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  • 9
    Electronic Resource
    Electronic Resource
    On a Class of Optimal Control Problems with State Jumps (1998)
    Springer
    Journal of optimization theory and applications 98 (1998), S. 65-82 
    Details
    ISSN: 1573-2878
    Keywords: Optimal control ; switching times ; state jumps ; transformations ; optimal parameter selection problem ; automatic differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, we consider a class of optimal control problems in which the dynamical system involves a finite number of switching times together with a state jump at each of these switching times. The locations of these switching times and a parameter vector representing the state jumps are taken as decision variables. We show that this class of optimal control problems is equivalent to a special class of optimal parameter selection problems. Gradient formulas for the cost functional and the constraint functional are derived. On this basis, a computational algorithm is proposed. For illustration, a numerical example is included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022684730236
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  • 10
    Electronic Resource
    Electronic Resource
    Co-localization of CD9 and GPIIb-IIIa (αIIb β3 integrin) on activated platelet pseudopods and α-granule membranes (1997)
    Springer
    Journal of molecular histology 29 (1997), S. 153-165 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract CD9 is a 24-kDa membrane glycoprotein expressed on the surface of human platelets and potentially involved in cellular activation and adhesion functions. This protein belongs to a recently delineated family of cell-surface antigens that span the membrane four times, called tetraspans, and found mainly in leucocytes and tumour cells. As a first approach to clarify the function of CD9, we used immunoelectron microscopy to determine the localization of this antigen in human platelets, and compared its distribution with that of the GPIIb-IIIa integrin, the platelet receptor for fibrinogen. Monoclonal antibodies against CD9 (MAb7) and GPIIb-- IIIa (HP1--1D) coupled to colloidal gold of different sizes (5 and 15 nm) were incubated with intact platelets in suspension or on ultrathin sections of platelets embedded in LR white. CD9 was found in association with GPIIb--IIIa on the inner face of α-granule membranes. These two antigens also co-localized on pseudopods of activated platelets and in contact regions between adjacent platelets. CD63, another member of the tetraspan family, was absent from α-granules but was associated with lysosomal structures. Flow cytometric analysis of platelet CD9 with a series of monoclonal antibodies revealed an increased expression upon thrombin stimulation, confirming the presence of an intracellular granular pool. The observation that CD9 and GPIIb-- IIIa are stored in the same intracellular structures and migrate to the same activation zones after platelet stimulation lends support to previous suggestions of a close association between CD9 and GPIIb--IIIa in human platelets and of a possible involvement of CD9 in adhesive functions of platelets
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026437522882
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