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  • Springer  (51)
  • 1995-1999  (51)
  • 1
    Electronic Resource
    Electronic Resource
    Full wave electromagnetic simulation of electrooptic high-speed probes (1996)
    Springer
    Optical and quantum electronics 28 (1996), S. 765-782 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract This paper outlines the process of modelling external electrooptic probes mounted on coplanar waveguides (CPW). The techniques used to describe the electromagnetic properties of the external probes are the finite difference time domain (FDTD) method and the finite difference transmission line method (FDTLM). These full wave techniques are time domain in nature that must be Fourier transformed to describe important frequency domain characteristics such as scattering parameters. The optical retardation of the probe is related to the full wave analysis through a commonly used grid size that results in a generalized basis for a complete electrooptic system analysis including a unique definition of an electrooptic transfer function,H(ω). Following the field simulation, the properties of the probe (invasiveness, retardation, signal distortion and group delay) are presented. Procedures for optimizing models for probe tips are discussed and related to a first-order model that has been developed. The results indicate that these probes can be simulated successfully on moderately sized Unix work stations and that the optimization of probe models must include the full wave simulation in the definition of the necessary gradients for the optimization process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00820148
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of fluorination of alumina support on activity of platinum catalysts for complete oxidation of benzene (1997)
    Springer
    Catalysis letters 49 (1997), S. 155-161 
    Details
    ISSN: 1572-879X
    Keywords: fluorination ; alumina ; platinum catalysts ; oxidation ; oxidation of benzene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Platinum supported on fluorinated alumina is more active for the total oxidation of benzene than is the catalyst with the same Pt loading supported on hydrophilic unfluorinated alumina. The Pt-F/alumina catalyst contains well-dispersed small Pt particles, in contrast to Pt/alumina. The high dispersion is a consequence of a strong metal-support interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019065507551
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  • 3
    Electronic Resource
    Electronic Resource
    Differences in Bone Resorption after Menopause in Japanese Women with Normal or Low Bone Mineral Density: Quantitation of Urinary Cross-Linked N-Telopeptides (1998)
    Springer
    Calcified tissue international 62 (1998), S. 395-399 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Type I-N-telopeptides — Bone resorption — Bone mineral density — Menopause — Osteoporosis.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The objective of this study was to examine the value of NTx, a urinary cross-linked N-telopeptides of type I collagen, as a marker of bone resorption. We assessed changes in pre- and postmenopausal bone resorption by evaluating the correlation of NTx with L2–4 bone mineral density (BMD) in a total of 1100 Japanese women, aged 19–80 years [272 premenopausal (45.2 ± 6.2 years) and 828 postmenopausal (59.5 ± 6.2 years)]. Postmenopausal women were divided into three groups based on the range of BMD (normal, osteopenic, and osteoporotic). Within each group, subjects were further segregated according to years since menopause (YSM). NTx values were then evaluated for each group. Our results showed that BMD was significantly decreased (P 〈 0.05) and NTx was significantly increased (P 〈 0.01) after menopause in age-matched analysis. Consistent with a previous report, NTx was inversely correlated with BMD for the entire cohort of study subjects (r =−0.299), although NTx correlated better with premenopausal than postmenopausal BMD (r =−0.240 versus r =−0.086). This may have been due to the fact that elevated values of NTx were exhibited over the entire range of BMD present in the postmenopausal women, suggesting that NTx might respond faster to the estrogen withdrawal than BMD. In all postmenopausal women, regardless of the range of BMD, the increase in NTx reached a peak within 5 YSM. After 11 YSM, however, NTx remained elevated in the osteoporotic group but it decreased in the osteopenic group, and showed no significant change in the group of postmenopausal women with normal BMD. These findings suggest that bone resorption is dramatically increased within 5 years after menopause but remains increased only in osteoporotic women.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900451
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  • 4
    Electronic Resource
    Electronic Resource
    Different spatial structures between network regions and active regions indicated by TRACE 171 Å observation (1999)
    Springer
    Solar physics 190 (1999), S. 79-90 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract By comparing TRACE 171 Å observations with photospheric magnetograms, we find that the root of TRACE 171 Å emission is centered in magnetic elements in simultaneous Huairou photospheric magnetogram and the luminosity of TRACE 171 Å emission is not always in proportion to the strength of the corresponding photospheric magnetic field. While TRACE emission from an active region shows an obvious upward extension as a whole, fibril-like emissions from network elements show little extension along the structure from the root of each emission to 40′′ higher up in the solar atmosphere. Together with previous studies by Zhang and Zhang (1999, 2000), it is suggested that the magnetic fields in active regions and quiet-Sun regions present different spatial structures from the solar photosphere to the chromosphere and maybe even in the corona.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005276217089
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  • 5
    Electronic Resource
    Electronic Resource
    Geostatistical scaling of canopy water content in a California salt marsh (1998)
    Springer
    Landscape ecology 13 (1998), S. 79-92 
    Details
    ISSN: 1572-9761
    Keywords: geostatistics ; scaling ; grain ; extent ; canopy water content ; salt marsh ; remote sensing ; Airborne ; Visible/Infrared Imaging Spectrometer (AVIRIS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Remote sensing data are typically collected at a scale which is larger in both grain and extent than traditional ecological measurements. To compare with remotely sensed data on a one-to-one basis, field measurements frequently must be rescaled to match the grain of image data. Once a one-to-one correspondence is established, it may be possible to extrapolate site based relationships over a wider extent. This paper presents a methodology for rescaling the grain of ecological field data to match the grain of remotely sensed data and gives an example of the method in verification of remote sensing estimates of canopy water content in a tidal salt marsh. We measured canopy water content at 169 points on a semi-regular grid in the Petaluma Marsh, CA. A variogram describing the spatial correlation structure of the canopy water content was calculated and modeled. Ordinary kriging estimates of the canopy water content were calculated over blocks corresponding to image pixels acquired by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). A water content index was determined from the reflectance data by calculating the area of a water absorption feature at 970 nm. A regression developed between the blocks and the pixels at the site was extrapolated over the image to obtain an estimate of canopy water content for the entire marsh. The patterns of canopy water content at the site and landscape levels suggest that different processes are important for determining patterns of canopy water content at different spatial extents. The errors involved in the rescaling procedures and the remote sensing interpretation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007961516096
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  • 6
    Electronic Resource
    Electronic Resource
    Stress effect and evidence of ferroelectric weakening in highly c-axis-oriented PbTiO3 thin films (1998)
    Springer
    Applied physics 66 (1998), S. 345-349 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 68.55.J; 78.30.Hv; 77.55.+f
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: 3 were successfully grown on Pt-coated SrTiO3 single-crystal substrates by metalorganic chemical vapor deposition (MOCVD) and were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. The as-deposited thin films were found to be highly (001)-oriented with an average grain size of about 0.3 μm. Both a decrease of the tetragonality and a frequency downshift of the long-wavelength optical phonons were observed and attributed to the effect of compressive stress in the thin films. However, Raman scattering studies estimated a stress value of 2.6 GPa, which is much larger than the value of 0.75 GPa obtained from the XRD analyses. Raman spectroscopic studies also confirmed the grain-size-related disorder feature in the as-grown PbTiO3 thin films. Structural investigations implied the weakening of ferroelectricity in the heteroepitaxial ferroelectric thin films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390050676
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  • 7
    Electronic Resource
    Electronic Resource
    E(transverse optical)-mode properties in the LiTaO3:Nd crystal at room temperature (1995)
    Springer
    Applied physics 60 (1995), S. 317-320 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 78.30.−j 63.20.−e
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. E(TO)-mode properties in LiTaO3:Nd crystal were examined by analyzing the Raman spectra measured. E(TO) modes appear in the transverse A 1 spectrum. Their intensities obviously increase in the E and E+A 1 mixed-symmetry spectra but decrease in the E spectrum which shows new vibrational modes. In particular, in the transverse-E spectrum of y(xz)y¯ geometry, the properties of E(TO) modes are similar to those of pure LiTaO3 of the same geometry, whereas in the transverse-E spectrum in x(yz)x¯ geometry these modes are turned into A 1 (TO) modes. We attribute these properties to both the surface strain produced by mechanical polishing of the sample and the microstructural change of the LiTaO3 crystal resulting from Nd doping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01538411
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  • 8
    Electronic Resource
    Electronic Resource
    E(transverse optical)-mode properties in the LiTaO3: Nd crystal at room temperature (1995)
    Springer
    Applied physics 60 (1995), S. 317-320 
    Details
    ISSN: 1432-0630
    Keywords: 78.30.-j ; 63.20.-e
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract E(TO)-mode properties in LiTaO3:Nd crystal were examined by analyzing the Raman spectra measured.E(TO) modes appear in the transverseA 1 spectrum. Their intensities obviously increase in theE andE+A 1 mixed-symmetry spectra but decrease in theE spectrum which shows new vibrational modes. In particular, in the transverse-E spectrum of y(xz) $$\bar y$$ geometry, the properties ofE(TO) modes are similar to those of pure LiTaO3 of the same geometry, whereas in the transverse-E spectrum in x(yz) $$\bar x$$ geometry these modes are turned intoA 1 (TO) modes. We attribute these properties to both the surface strain produced by mechanical polishing of the sample and the microstructural change of the LiTaO3 crystal resulting from Nd doping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01538411
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  • 9
    Electronic Resource
    Electronic Resource
    Raman-spectroscopy study of PbTiO3 thin films grown on Si substrates by metalorganic chemical vapor deposition (1996)
    Springer
    Applied physics 62 (1996), S. 281-284 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 78.30.Hv; 63.20. ; e; 81.15.Gh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract.  Raman spectra have been investigated in PbTiO3 thin films grown on Si by metalorganic chemical vapor deposition. A large grazing-angle scattering technique was taken to measure the temperature dependence of Raman spectra below room temperature. All Raman modes in the thin films are assigned and compared with those in the bulk single crystal, a new A 1(TO) soft mode at 104 cm-1 was recorded which satisfies the Curie-Weiss relation ω2=A(T c−T). Intensities of the A 1(1TO) and E(1TO) modes were anomalously strengthened with increasing temperature. Raman modes for the thin films exhibit remarkable frequency downshift and upshift which is related to the effect of internal stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01575095
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  • 10
    Electronic Resource
    Electronic Resource
    Raman-spectroscopy study of PbTiO3 thin films grown on Si substrates by metalorganic chemical vapor deposition (1996)
    Springer
    Applied physics 62 (1996), S. 281-284 
    Details
    ISSN: 1432-0630
    Keywords: 78.30.Hv ; 63.20. — e ; 81.15.Gh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Raman spectra have been investigated in PbTiO3 thin films grown on Si by metalorganic chemical vapor deposition. A large grazing-angle scattering technique was taken to measure the temperature dependence of Raman spectra below room temperature. All Raman modes in the thin films are assigned and compared with those in the bulk single crystal, a newA 1(TO) soft mode at 104 cm−1 was recorded which satisfies the Curie-Weiss relationω 2 =A(T c −T). Intensities of theA 1(1TO) andE(1TO) modes were anomalously strengthened with increasing temperature. Raman modes for the thin films exhibit remarkable frequency downshift and upshift which is related to the effect of internal stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01575095
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