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  • 1
    Electronic Resource
    Electronic Resource
    Crystal structure of poly(p-phenylene) prepared by organometallic technique (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 293-297 
    Details
    ISSN: 0887-6266
    Keywords: poly(p-phenylene) from organometallic polymerization, crystal structure of ; crystal structure of poly(p-phenylene) from organometallic preparation ; X-ray diffraction of organometallically produced poly(p-phenylene) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The two-dimensional crystal structure of poly(p-phenylene) is investigated by linkedatom Rietveld analysis of the x-ray diffraction powder profile. Two molecular chains are packed in a rectangular pgg unit cell (a = 0.779 nm; b = 0.551 nm) with a paracrystalline shift distortion along the chain axis. The molecular conformation is not rigidly planar; rotations between adjacent phenyl-ring planes in a molecule alternate with an angle of about 20°. The setting angle between the mean molecular plane and the a axis is 55.5°.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090300309
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  • 2
    Electronic Resource
    Electronic Resource
    Dual wavelength optical bistability and multistability in a symmetric self-electro-optic effect device based on Wannier–Stark localization (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1679-1681 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A tunable optical switch has been studied of a symmetric self-electro-optic effect device based on Wannier–Stark localization (WSL) in GaAs/AlAs superlattices. This device is driven by two different wavelengths for a signal beam and a control beam. Clear bistability and/or triple stability are demonstrated by controlling the illumination wavelengths. The tunability of the switching properties is clearly explained by the WSL mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107235
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of ordering on the operation of AlGaInP lasers grown by metalorganic chemical vapor deposition (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1959-1961 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed large differences in the lasing wavelength and threshold current for [11¯0]- and [110]-striped AlGaInP lasers that are fabricated from a single wafer grown by metalorganic chemical vapor deposition. With the laser stripe aligned parallel to the [110] direction, the lasing wavelength is about 6 nm shorter than that with the [11¯0] stripe. The threshold current (Ith) of the [110]-striped laser is 10 mA higher than that of the [11¯0]-striped laser. The differences are found to be well explained by the splitting of the valence band due to the (111) ordering in the AlGaInP lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108376
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  • 4
    Electronic Resource
    Electronic Resource
    Closure of the micropyle during embryonic development of some pelagic fish eggs (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 40 (1992), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The fine structure of the egg envelope and micropyle was studied in unfertilized and developing eggs of the flounder Paralichthys olivaceus (Temminck & Schlegel), the Alaska pollack Theragra chalcogramma (Pallas), the Japanese tilefish Branchiostegus japonicus (Houttuyn) and the porgy Pagrus major (Temminck & Schlegel). The outer envelope surface of the unfertilized egg was wrinkled, while the inner surface was folded. The micropyle of the unfertilized egg consisted of a shallow vestibule and a distinct canal. The micropylar region of the inner surface of the envelope had a conical- or bowl-shaped protrusion. In developing eggs, the thickness of the envelope decreased and showed smooth outer and inner surfaces which indicated that it had been stretched tangentially at the time of the perivitelline space formation. The lumen of the micropylar canal was invariably occupied with envelope material. We postulate that the blockage of the micropylar canal is a result of the stretching of the envelope. The closure of the micropyle inhibits sperm and external pathogens from penetrating into the perivitelline space and seems to be involved in both the permanent prevention of polyspermy and the protection of the developing embryo from bacterial infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1992.tb02569.x
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  • 5
    Electronic Resource
    Electronic Resource
    On the convergence of some quasi-Newton methods for nonlinear equations with nondifferentiable operators (1992)
    Springer
    Computing 49 (1992), S. 87-94 
    Details
    ISSN: 1436-5057
    Keywords: 65H10 ; 65G10 ; Nonlinear equations ; nondifferentiable operator ; quasi-Newton method ; convergence theorems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit wird die Konvergenz gewisser Quasi-Newton-Verfahren zur Lösung von nichtlinearen GleichungenAx+g(x)=0 aufD⊄R n untersucht, wobeiA eine (n×n)-Matrix undg ein nichtdifferenzierbarer, aber Lip-schitz-stetiger Operator ist. Mittels intervallanalytischer Techniken wird ein neuer Konvergenzsatz für die Verfahren hergeleitet.
    Notes: Abstract In this paper, we study the convergence of some quasi-Newton methods for solving nonlinear equationAx+g(x)=0 in a domainD⊄R n , whereA is ann×n matrix andg is a nondifferentiable but Lipschitz continuous operator. By interval analysis, we give a new convergence theorem of the methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02238652
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  • 6
    Electronic Resource
    Electronic Resource
    Pseudoenhancement of intervertebral disc herniation (1992)
    Springer
    Neuroradiology 34 (1992), S. 271-272 
    Details
    ISSN: 1432-1920
    Keywords: Disc herniation ; Gadolinium-DTPA-enhanced MRI ; Epidural venous plexus ; Epidural fibrosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two patients with intervertebral disc herniation appeared to demonstrate abnormally diffuse and intense enhancement of the disc after intravenous administration of gadolinium-DTPA for MRI. Surgery disclosed a dilated epidural venous plexus in one and vascular granulation tissue in the other, associated with the herniated disc material. The mechanism of this “pseudoenhancement” of the disc appears to be a partial volume effect of disc material and the adjacent veins or granulation tissue. Pseudoenhancement of a herniated disc should be included in the differential diagnosis of a diffusely enhancing epidural mass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588179
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  • 7
    Electronic Resource
    Electronic Resource
    Fundamental characteristics of human limb electrical impedance for biodynamic analysis (1992)
    Springer
    Medical & biological engineering & computing 30 (1992), S. 465-472 
    Details
    ISSN: 1741-0444
    Keywords: Biodynamic analysis ; Bioelectrical impedance ; Sports skill
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The paper describes the use of human-limb impedance for biodynamic analysis. The change of human-limb impedance during movement was measured, and was found to be related to kinematic and kinetic parameters. Strong relationships were found between the velocity of change of the forearm impedance and the angular velocity of the elbow joint (correlation coefficient r=−0·97), between the change of foream impedance and the acceleration of a human limb (r=0·86), and between the change of forearm impedance and the velocity of a human limb (r=0·79). A change of upper-limb impedance was caused by a change in a sectional area of muscular tissue in the measured part and a change of blood volume during movement of an upper limb. In tennis, there was a strong relationship between a change of forearm impedance and ball velocity (r=0·87). Impedance waveforms were useful for analysis of the movement pattern and the stability of movement in tennis. This method has the following characteristics: (a) it does not have a spatial and temporal limitation for measurement; (b) the subject is scarcely restricted in movement; (c) the data processing can be handled easily and quickly; (d) impedance waveforms inherently show magnitude, form and stability of movement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457823
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  • 8
    Electronic Resource
    Electronic Resource
    Impedance plethysmography for blood flow measurements in human limbs (1992)
    Springer
    Medical & biological engineering & computing 30 (1992), S. 518-524 
    Details
    ISSN: 1741-0444
    Keywords: Blood flow in human limb ; Cross-sectional area ; Impedance plethysmography ; Strain gauge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The cross-sectional area of a limb varies along the extremity. This is of great importance when impedance plethysmography is used for limb blood flow studies. The actual measurement site, as well as the interelectrode distance, must be carefully selected to avoid underestimation of the blood flow value. The distance between the potential electrodes should be less than 10 cm for an adult subject.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457831
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