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  • 1
    Electronic Resource
    Electronic Resource
    Anisotropy beneath the Iberian Peninsula: The Contribution of the ILIHA-NARS Broad-band Experiment (1998)
    Springer
    Pure and applied geophysics 151 (1998), S. 395-405 
    Details
    ISSN: 1420-9136
    Keywords: Key words: Anisotropy, shear-wave splitting, Iberian Peninsula, regional variations.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —The presence of anisotropy beneath the Iberian Peninsula and its main distinctive features can be established through the analysis of teleseismic shear-wave splitting observed in the ILIHA-NARS experiment. In this experiment, an homogeneous data set is provided by a network of 14 broad-band stations deployed over the entire peninsula for about one year. Even if technical problems led to an amount of data smaller than expected, significant variations in the inferred fast velocity direction are observed for stations located in different Iberian domains. The stations in Central and East Iberia show a fast velocity direction oriented roughly E–W, coincident with previous results in Toledo. A clearly different NE–SW direction is observed in the Ossa-Morena zone, supporting the image from a previous regional experiment. The observed delay times lie between 0.5 and 1 s. Although large-scale mechanisms, such as the absolute plate motion of Eurasia, can be invoked to explain the origin of anisotropic features in many sites, the regional variations observed in some domains imply that differentiated origins of the anisotropy have to be considered, probably related to the particular tectonics in the area. An interesting example of this fact is provided by the stations in the Betic chain; the fast velocity direction inferred for a station located in the limit of the External Betics (South Iberian domain), oriented N80°E, is clearly different from the N15–35°E direction observed in the Internal Betics (Alboran crustal domain), the origin of which has to be related to the Alpine building of the chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050119
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  • 2
    Electronic Resource
    Electronic Resource
    Variation of Shear-wave Residuals and Splitting Parameters from Array Observations in Southern Tibet (1998)
    Springer
    Pure and applied geophysics 151 (1998), S. 407-431 
    Details
    ISSN: 1420-9136
    Keywords: Key words: Shear waves, anisotropy, Tibet.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —A tight array of seismographs spanning a 500 km traverse of southern Tibet resolved anisotropy from SKS with a spatial variation of its direction and an increase northward of the splitting delay, as well as of its first arrival residual. Both waves split by velocity anisotropy are slow relative to P and their waveform analysis may be interpreted to suggest attenuation anisotropy. The array here provides examples of residuals and splitting of other S waves which do not tightly conform to the anisotropy assumed in the simplest model of olivine of transverse isotropy with horizontal symmetry axis. S waves are also split, with parameters which vary along the array, and hence are relevant to near-receiver structure like those of SKS. Their splitting delay, for non-vertical incidence and polarization, appears larger than that for SKS. Residuals of S-wave first arrivals and splitting delays increase less northwards for S than SKS. Anisotropy with a slow vertical axis may account for these observations. Its origin may be related to horizontal shear or flow in low-velocity layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050120
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  • 3
    Electronic Resource
    Electronic Resource
    Utilization of yolk reserves during post-embryonic development in three teleostean species: the sea bream Sparus aurata, the sea bass Dicentrarchus labrax, and the pike-perch Stizostedion lucioperca (1996)
    Springer
    Marine biology 126 (1996), S. 539-547 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparative study of the use of yolk reserves during post-embryonic development was performed on three teleostean fishes of aquacultural interest: the sea bream Sparus aurata, the sea bass Dicentrarchus labrax, and the pike-perch Stizostedion lucioperca. The first part of the work was devoted to the structural development of the periblast, the vitellus and the oil globule during the endotrophic and endo-exotrophic phases of larval life. Observations using transmission electron microscopy revealed a perivitelline circulation system closely related to the liver, and suggested an important function of the periblast in the utilization of reserves. In the second part of the study, cytochemical reactions revealed the way in which the reserves are resorbed. Glycogen contained in the periblast at hatching was utilized during the endotrophic period. The successive appearance of lipoprotein particles in the periblast endoplasmic reticulum, Golgi apparatus, and perivetelline circulation zone is consistent with the mobilization of yolk and oil globule components. Comparison of fed and fasting individuals revealed that fasting tended to slow down rather than increase the utilization of reserves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00354636
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  • 4
    Electronic Resource
    Electronic Resource
    Allergic contact dermatitis from a beeswax nipple-protective (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Contact dermatitis 33 (1995), S. 0 
    Details
    ISSN: 1600-0536
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0536.1995.tb02093.x
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  • 5
    Electronic Resource
    Electronic Resource
    Visible blind GaN p-i-n photodiodes (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 3303-3305 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the growth and characterization of GaN p-i-n photodiodes with a very high degree of visible blindness. The thin films were grown by low-pressure metalorganic chemical vapor deposition. The room-temperature spectral response shows a high responsivity of 0.15 A/W up until 365 nm, above which the response decreases by six orders of magnitude. Current/voltage measurements supply us with a zero bias resistance of 1011 Ω. Lastly, the temporal response shows a rise and fall time of 2.5 μs measured at zero bias. This response time is limited by the measurement circuit. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121631
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  • 6
    Electronic Resource
    Electronic Resource
    A rat G protein-coupled receptor selectively expressed in myelin-forming cells (1998)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 10 (1998), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: By screening an olfactory bulb cDNA library using dopamine receptor probes, we isolated the cDNA coding for the rat counterpart of an orphan receptor known as Edg-2, homologous to G protein-coupled receptors. In situ hybridization analysis showed that Edg-2 mRNA expression is restricted to myelinated structures, e.g. corpus callosum or peripheral nerves. A weaker expression in various peripheral organs was also detected in newborns. A 3.8-kb transcript was found at high levels in highly myelinated brain structures and sciatic nerve, and, at lower levels, in poorly myelinated peripheral organs, consistent with its occurrence in Schwann cells in the peripheral nervous system. One hundred percent of Edg-2 mRNA-containing cells in the brain also expressed mRNA encoding myelin-basic-protein, a marker of oligodendrocytes. This restricted olygodendrocytes localization was confirmed by the absence of cellular colocalization of Edg-2 and glial fibrillary acidic protein, an astrocytic marker. During prenatal development, Edg-2 mRNA expression was high in the cortical neuroepithelium and meningeal layer at E16, extended later to other neuroepithelia, and disappeared shortly after birth. During brain postnatal development, Edg-2 mRNA expression in myelinated structures followed a caudo-rostral gradient, similar to that of myelination. Thus, Edg-2 is the first G protein-coupled receptor found to be selectively expressed in myelin-forming cells in the nervous system and its temporal expression pattern is consistent with a dual role (i) in neurogenesis, during embryonic development, and (ii) in myelination and myelin maintenance, during postnatal life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.1998.00117.x
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  • 7
    Electronic Resource
    Electronic Resource
    Nonspecific bronchial hyperresponsiveness and development of asthma in children with hay fever (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Pediatric allergy and immunology 6 (1995), S. 0 
    Details
    ISSN: 1399-3038
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: It has been suggested that patients with allergic rhinitis who present nonspecific bronchial hyperresponsiveness (BHR) are those most likely to develop asthma. Therefore, a study was conducted in children with rhinoconjunctivitis to ascertain whether BHR to methacholine might predict the development of asthma in these patients. Fifteen patients with hay fever and no previous symptoms of asthma were selected. All underwent clinical symptom tests and methacholine tests, during the pollen season in the 4 consecutive years following the start of the study. At the end of this period, 5 patients had developed asthma. It may thus be affirmed that, in this group, neither the presence nor the degree of previous BHR was useful for predicting which patients would later develop asthma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3038.1995.tb00285.x
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  • 8
    Electronic Resource
    Electronic Resource
    Comparison of gain and threshold current density for InGaAsP/GaAs (λ=808 nm) lasers with different quantum well thickness (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8832-8834 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated the quantum-size effects of quantum well (QW) on gain and threshold current density for InGaAsP/GaAs (λ=808 nm) laser diodes. In this work, a comparison is made of lasers with different QW thickness while keeping the optical confinement factors constant. We found that the threshold current density and differential efficiency were not affected by narrowing the QW thickness. The theoretical model taking into account the mixing of the valence bands and momentum relaxation for InGaAsP/GaAs lasers with spontaneous emission (optically pumped) measurement shows that the absence of difference between these structures can be attributed to the high relaxation rate. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362508
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  • 9
    Electronic Resource
    Electronic Resource
    High power asymmetrical InAsSb/InAsSbP/AlAsSb double heterostructure lasers emitting at 3.4 μm (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1194-1196 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Midinfrared lasers with an asymmetrical InPAsSb/InAsSb/AlAsSb double heterostructure are reported. Using the asymmetrical double heterostructure, p- and n-cladding layers are separately optimized; high energy-gap AlAsSb (Eg(approximate)1.5 eV) for the p-type cladding layer to reduce the leakage current, and thus to increase To, and low energy-gap InPAsSb (Eg(approximate)0.5 eV) for the n-cladding layer to have low turn-on voltage. 100-μm-width broad-area lasers with 1000 μm cavity length exhibited peak output powers of 1.88 W in pulse and 350 mW in continuous wave modes per two facets at T=80 K with To of 54 K and turn-on voltage of 0.36 V. Maximum peak output powers up to 6.7 W were obtained from a laser bar of total aperture of 400 μm width and cavity length of 1000 μm, with a differential efficiency of 34% and far-field beam divergence narrower than 40° at 80 K. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123496
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  • 10
    Electronic Resource
    Electronic Resource
    High-temperature continuous-wave operation of λ∼8 μm quantum cascade lasers (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 173-175 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report single-mode continuous-wave operation of a λ∼8 μm quantum cascade laser at 140 K. The threshold current density is 4.2 kA/cm2 at 300 K in pulsed mode and 2.5 kA/cm2 at 140 K in continuous wave for 2 mm long index-guided laser cavities of 20 μm width. Wide stripe (W∼100 μm), index-guided lasers from the same wafer in pulsed operation demonstrate an average T0 of 210 K with other wafers demonstrating a T0 as high as 290 K for temperatures from 80 to 300 K. This improvement in high-temperature performance is a direct result of three factors: excellent material quality, a low-loss waveguide design, and a low-leakage index-guided laser geometry. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123284
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