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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 71 (1988), S. 220-220 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0375-9474
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 1867-1872 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The heterogeneous nucleation and subsequent growth of chemical vapor deposited copper using hexafluoroacetylacetonate-Cu(I)-trimethylvinylsilane on physical vapor deposited tantalum and chemical vapor deposited titanium nitride was studied by means of electron microscopy and atomic force microscopy. It was found that the nucleation densities are about two orders of magnitude higher on TiN than on Ta. This leads to an increased roughness of films deposited on Ta compared to those produced on TiN. Moreover, the Cu films on the Ta substrate show a large number of voids, whereas no such voids were observable in the Cu films deposited on top of TiN. A simplified model for the influence of gas-surface reaction and surface self-diffusion on the shape of the Cu grains was developed. This model, which is supported by the experimental data, shows that if the grain shape changes from spherical to nonspherical before coalescence with neighboring grains, voids occur. A critical grain size and nucleation density of about 150 nm and 5×1013 m−2, respectively, were calculated for the deposition conditions used in this work. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5149-5154 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Extremely thin titanium nitride (TiN) barrier layers for Cu based interconnects were deposited using metal organic chemical vapor deposition. The effect of the subsequently performed nitrogen/hydrogen plasma treatment on the microstructure, composition, and electrical properties of these films is studied using conventional and high resolution transmission electron microscopy, Auger electron spectroscopy, and four point probe resistivity measurements. In the studied system the crystallization of the TiN film starts from an amorphous matrix and a polycrystalline morphology is developed upon the H2/N2 plasma treatment. After a short plasma treatment, most of the film is already crystalline and consists of grains of a few nanometers in diameter. Continued plasma treatment leads to grain growth and a significant reduction of contaminants such as oxygen and carbon. The resistivity of the films drops with plasma treatment time, and a correlation between resistivity and oxygen content is found, which suggests that oxygen in the grain boundaries plays a decisive role for the resistivity of the films. It is shown that the oxygen in the grain boundaries leads to an electron reflectance of 0.9. Thus, the oxygen accumulation in the grain boundaries is the limiting factor for the reduction of film resistivity by plasma treatment. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 184 (1999), S. 403-412 
    ISSN: 1432-1351
    Keywords: Key words Emmetropization ; Myopia ; Dopamine ; 6-Hydroxy-dopamine ; Crystalline lens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We investigated the suitability of fishes as animal models to study the involvement of the retinal dopaminergic system in the visually guided control of eye growth (emmetropization). Advantages of such a model system are (i) that all dopaminergic cells in the retina can be destroyed without apparent damage to other neurons, (ii) simple optical design and short depth of field of the eye, and (iii) continuous growth throughout life. Depleting the retina of dopamine in Aequidens pulcher (Cichlidae) had no apparent effect on refractive state, since size and focal length of the eye were reduced by the same amount. Furthermore, imposed defocus was compensated at a normal rate in spite of the absence of retinal dopamine. In A. pulcher, the dopaminergic system of the retina thus appears not to have an essential role in emmetropization. Our results furthermore suggest that in eyes of more complicated optical design, manipulation of the retinal dopaminergic system may lead to unrelated effects indistinguishable from direct interference with emmetropization. A major disadvantage of the fish model was that refractive state of the eye could not be measured accurately in vivo with standard methods.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 184 (1999), S. 361-369 
    ISSN: 1432-1351
    Keywords: Key words Color vision ; Chromatic aberration ; Spherical aberration ; Depth of field ; Pupil shape
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The focal length of the vertebrate eye is a function of wavelength, i.e. the eye suffers from longitudinal chromatic aberration. Chromatic defocus is a particularly severe problem in eyes with high light-gathering ability, since depth of field is small due to a pupillary opening that is large in relation to the focal length of the eye. Calculations show that in such eyes only a narrow spectral band of light can be in focus on the retina. For the major part of the visual spectrum, spatial resolution should be limited by the optics of the eye and far lower than the resolving power achievable by the retinal cone photoreceptor mosaic. To solve this problem, fishes with irises unresponsive to light have developed lenses with multiple focal lengths. Well-focused images are created at the wavelengths of maximum absorbance of all spectral cone types. Multifocal lenses also appear to be present in some terrestrial species. In eyes with mobile irises, multifocal lenses are correlated with pupil shapes that allow all zones of the lens, with different refractive powers, to participate in the imaging process, irrespective of the state of pupil constriction.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 179 (1996), S. 837-842 
    ISSN: 1432-1351
    Keywords: Eye growth ; Emmetropization ; Monochromatic light ; Fish ; Chromatic aberration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract By rearing fish in various monochromatic illuminations we investigated (1) the potential for compensation of refractive error due to chromatic aberration, (2) the contributions of the chromatic channels to emmetropization, and (3) the role of color cues in the control of eye growth. Cichlid fish (Aequidens pulcher) were reared for 6 months (12 h light/12 h dark) in monochromatic lights (623.5, 534.1, 485.0 nm; spectral purity 5–10 nm). Light levels were isoirradiant at 1.1·1012 quanta/s/cm2. Two control groups were reared in white light with down-welling illuminances of 0.2 and 33 lx. Nasotemporal diameters (NTDs) of the eyes were measured in relation to lens size. Due to the oblique axis of highest acuity vision in cichlids, NTD is considered to be a more important dimension than axial length. Variances in NTD were equally small in all rearing groups. NTDs were enlarged with increasing wavelengths of the rearing lights with highly significant values over controls in the red-light group. The wavelength-dependent size of the eyes matched the changes in focal length due to longitudinal chromatic aberration. Complete recovery from eye enlargement was observed after fish reared in red light were exposed to a white light regime for 5 weeks. Small variances in NTD in all groups indicated stringent control of eye growth in the absence of color cues. The reversibility of the increase in NTD in fish reared in red light suggests that the eyes were emmetropized by visually guided mechanisms. Eye size in fish reared in white light was intermediate between the values expected if only blue-sensitive single or the red- and green-sensitive double cones contributed to the control of eye growth. This suggests that all chromatic channels participate in emmetropizing the fish eye.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The transverse energy cross-sectiondσ/dE T has been measured in the pseudorapidity region 0.6〈η〈2.4 for hadron-lead collisions at 200 GeV/c incident hadron momentum. TheE T distribution extends to 40 GeV, which is twice the kinematic limit forp-p collisions at the same incident beam momentum. The distribution ofE T is found to shift towards low pseudorapidities with increasing total transverse energy.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In a study ofpp collisions at $$\sqrt s = 63$$ GeV with more than 29 GeV total transverse energy emitted into 1.8 units of rapidity in the central region, we have extracted a sample of 4-jet events and compared it with models of the two sources of 4-jet production: double bremsstrahlung and double parton scattering. The data cannot be described by bremsstrahlung alone, and we extract the fraction of 4-jet events attributed to double parton scattering for various definitions of the 4-jet sample. We determine the double parton scattering/2-jet yield ratio, and this leads to a determination of the proton radius. We discuss the implications of our observations for the general understanding of high-ΣE T events.
    Type of Medium: Electronic Resource
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