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  • 1
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Panretinal photocoagulation has been demonstrated to have a beneficial effect on the natural history of diabetic retinopathy. However, it is associated with detectable loss of retinal function. To determine the best coagulation technique we conducted a prospective study in 32 eyes of 16 patients. We investigated retinal function in relation to spot size and scatter density after panretinal laser coagulation. One eye was treated with approximately 400 comparatively large laser spots (0.6–0.8 mm diameter), whereas the fellow eye was coagulated with approximately 1500 small spots (0.2–0.4 mm diameter), so that the total coagulated area was almost the same in both eyes. Subjective parameters (visual acuity, perimetry, dark adaptation, photostress), as well as objective functions (electroretinogram, ERG; electro-oculogram, EOG), were studied preoperatively and then postoperatively over a time span of 6 months. Pronounced impairment of retinal function was detected, which recovered after 3 months on the average. When the pairs of eyes were compared, persistent visual field scotomas as detected by computerized static perimetry, occurred less frequently in eyes subjected to small coagulation spots, although this tendency was not statistically significant.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1424
    Keywords: Key words: SR — Ryanodine receptor — Calpains — p94
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. A 94 kDa large subunit thiol-protease, as identified by anti-calpain antibodies, has been isolated from skeletal muscle junctional sarcoplasmic reticulum (SR). This protease cleaves specifically the skeletal muscle ryanodine receptor (RyR)/Ca2+ release channel at one site resulting in the 375 kDa and 150 kDa fragments. The 94 kDa thiol-protease degrades neither other SR proteins nor the ryanodine receptor of cardiac nor brain membranes. The partially purified 94 kDa protease, like the SR associated protease, had an optimal pH of about 7.0, was absolutely dependent on the presence of thiol reducing reagents, and was completely inhibited by HgCl2, leupeptin and the specific calpain I inhibitor. However, while the SR membrane-associated protease requires Ca2+ at a submicromolar concentration, the isolated thiol-protease has lost the Ca2+ requirement. The 94 kDa thiol-protease had no effect on ryanodine binding but modified the channel activity of RyR reconstituted into planar lipid bilayer: in a time-dependent manner, the channel activity decreases and within several minutes the channel is converted into a subconducting state. The protease-modified channel activity is still Ca2+-dependent and ryanodine sensitive. This 94 kDa thiol-protease cross react with anti-calpain antibodies thus, may represent the novel large subunit of the skeletal muscle specific calpain p94.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The resonant photorefractive devices using low temperature AlGaAs/GaAs multiple-quantum-well structures in a parallel field geometry are demonstrated. The samples are semi-insulating as grown. The AsGa-related defects incorporated into the samples during low temperature growth provide the required deep centers. No proton implantation, Cr doping, or annealing is needed for device fabrication. In the photorefractive wave mixing experiment, an output diffraction efficiency higher than 0.84% and a two-wave-mixing gain of more than 3000 cm−1 are obtained under a dc electric field of 15 kV/cm. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 256-258 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical characteristics of rapid thermal oxides on Si1−x−yGexCy layers are reported. X-ray photoelectron spectroscopy results indicate segregation of Ge at the SiO2/Si1−x−yGexCy interface, a thin GeO2 layer at the oxide surface, and elemental Ge at the interface and in the oxide. The interface state density of the samples ranges from 3.0×1011 to 3.6×1012 eV−1 cm−2. All the samples show electron trapping behavior and the trap generation rate decreases with increasing C concentration. The charge-to-breakdown value and the oxide breakdown field are higher for Si0.887Ge0.113 than for Si1−x−yGexCy samples, and these values decrease with increasing C concentration. © 2000 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1463-1465 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The low-temperature grown AlGaAs/GaAs multiple quantum well structures were characterized by photoluminescence (PL) spectroscopy. The samples were grown at 270–400 °C and annealed at 500–900 °C. After anneal, photoluminescence quenching was observed for the samples grown at temperatures below 350 °C, and found to show a strong dependence on the growth and anneal temperatures. The luminescence intensity for the PL-quenched sample exhibits a power law dependence on the excitation level with an exponent close to 2, indicating a bimolecular recombination process in parallel with strong nonradiative recombination. The photoluminescence quenching upon anneal is attributed to the formation of arsenic clusters that serve as new nonradiative recombination channels. © 1998 American Institute of Physics.
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  • 6
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0022-328X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-1383
    Keywords: distributed real-time systems ; communication protocols ; fault-tolerant systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Real-time embedded systems have evolved during the past several decades from small custom-designed digital hardware to large distributed processing systems. As these systems become more complex, their interoperability, evolvability and cost-effectiveness requirements motivate the use of commercial-off-the-shelf components. This raises the challenge of constructing dependable and predictable real-time services for application developers on top of the inexpensive hardware and software components which has minimal support for timeliness and dependability guarantees. We are addressing this challenge in the ARMADA project. ARMADA is set of communication and middleware services that provide support for fault-tolerance and end-to-end guarantees for embedded real-time distributed applications. Since real-time performance of such applications depends heavily on the communication subsystem, the first thrust of the project is to develop a predictable communication service and architecture to ensure QoS-sensitive message delivery. Fault-tolerance is of paramount importance to embedded safety-critical systems. In its second thrust, ARMADA aims to offload the complexity of developing fault-tolerant applications from the application programmer by focusing on a collection of modular, composable middleware for fault-tolerant group communication and replication under timing constraints. Finally, we develop tools for testing and validating the behavior of our services. We give an overview of the ARMADA project, describing the architecture and presenting its implementation status.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Rheologica acta 25 (1986), S. 440-443 
    ISSN: 1435-1528
    Keywords: Nonlinear elastic constitutive model ; strain stiffening behavior ; membrane inflation ; extension ; natural rubber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A nonlinear, two constant stress-deformation form is deduced for elastic materials. At very large stretch ratios of greater than about 3 or 4, the model exhibits the strain stiffening behavior common to many elastomers. The constitutive form is very simple since the two material constants enter it as multiplying constants times certain nonlinear deformation terms. The model is evaluated with respect to data upon natural rubber under both uniaxial and bi-axial stress conditions. The model is also used to evaluate data obtained from a nonlinear membrane inflation experiment. The latter experimental capability and corresponding data are new.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0029-5981
    Keywords: hybrid finite element ; plate/shell ; laminated composites ; stress analysis ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A degenerated plate/shell element based on the combined energy variational principle and the equivalent single-layer model is proposed. It is derived from the 3-D continuum equation by imposing one constraint on the 3-D isoparametric solid element: a straight line normal to the mid-surface before deformation remains straight but not normal after deformation. The continuities of interlaminar stresses are satisfied at the interlaminar surface and the number of degrees of freedom per node is independent of the number of layers. In this work, the combined energy variational principle is used to overcome transverse stress continuity limitations of single-layer models. The traction-free conditions are satisfied on the upper and lower surfaces of a laminate by assuming the transverse stress components independently. The transverse normal strain is taken into account in order to consider the full 3-D effect in a laminated composite. The iso-function method and the classification method of the stress modes are used to construct the assumed stress field which contains a minimum number of stress modes and guarantees no zero energy mode in the element stiffness matrix. Three examples are presented to illustrate the efficiency and accuracy of the element.
    Additional Material: 6 Ill.
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