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  • 11
    Electronic Resource
    Electronic Resource
    Characterization of a Dopaminergic Receptor that Modulates Adrenomedullary Catecholamine Release (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 47 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Nicotine evokes the release of catecholamines from bovine adrenal glands perfused with oxygenated Krebs-bicarbonate solution. Two 2-min pulses of 5 μM nicotine, at 40-min intervals (S1 and S2), gave net catecholamine outputs of 45.2 ± 3.6 and 29.1 ± 3.5 μg/8 min, respectively. Apomorphine (1 or 10 μM) markedly inhibited catecholamine release during S2 to 9.1 ± 2.2 and 0.5 μg/8 min, respectively. Haloperidol (0.5 μM) reversed the inhibitory effects of apomorphine. Haloperidol alone enhanced catecholamine release induced by nicotine to 67.9 ± 7.9 μg/8 min. [3H]Spiperone binds to adrenomedullary membranes with a KD of 0.24 nM and a Bmax of 117 fmol/mg of protein. Whereas spiperone and haloperidol potently displaced such binding, 3,4-dihydroxyphenylethylamine (dopamine) and sulpiride were poorer displacers, and SCH23390, prazosin, phenoxybenzamine, propranolol, BAY-K-8644, and nitrendipine did not displace [3H]spiperone bound. These data strongly suggest that, as in the cat, the bovine adrenal medulla chromaffin cell contains a dopaminergic receptor that modulates the catecholamine secretory process triggered by stimulation of the nicotinic cholinoceptor. Such a receptor seems to be of the D2 type and might be involved in a sympatho-adrenal cooperative mechanism contributing to the maintenance of cardiovascular homeostasis during stressful situations as well as to the pathogenesis of hypertension. If so, selective dopaminergic agonists might prove clinically useful in the treatment of hypertension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb04513.x
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  • 12
    Electronic Resource
    Electronic Resource
    A NEW FUNCTIONAL FORM FOR ESTIMATING LORENZ CURVES (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Review of income and wealth 37 (1991), S. 0 
    Details
    ISSN: 1475-4991
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: There are several functional forms for estimating Lorenz curves from grouped data. Based on studies of the Spanish distribution of income, we propose a new functional form which provides very good fits. Our specification contains the Pareto Lorenz curve as a particular case, and allows one to compute easily, with the provided formulae, the Gini, Kakwani, and Chakravarty Inequality Indexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1475-4991.1991.tb00383.x
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  • 13
    Electronic Resource
    Electronic Resource
    Genetic differences between natural populations of diploid and tetraploid Dactylis glomerata ssp. izcoi (1997)
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 52 (1997), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Twenty-one natural populations (thirteen tetraploids and eight diploids) of Dactylis glomerata ssp. izcoi (an Iberian endemic) were evaluated in the field for three consecutive years, using two clones per genotype, to separate genetic and environmental factors. Many traits showed significant differences between ploidy levels, but all of them overlapped. Therefore, it is justified to include both cytotypes in a subspecies in which tetraploids could be autopolyploids. In general, however, diploids had shorter stomatal guard cells, lower seed production and were later heading than tetraploids. Within tetraploids, most traits differed significantly between and within populations. There was less inter- and intrapopulation variation in the diploids. The range of plant dimensions exceeded that of former descriptions of the sub-species, bringing it closer to ssp. glomerata. Inland populations were not qualitatively different from one coastal population. Diploid populations showed less risk of hypomagnesemia than tetraploids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1997.tb02359.x
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  • 14
    Electronic Resource
    Electronic Resource
    Experimental evidence of a crossover in the vortex dimensionality in high-Tc superconductors : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 6589-6591 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Quantum motion of vortices in high-temperature superconductors (HTSCs) was studied via magnetic relaxation measurements performed with a commercial superconducting quantum interference device magnetometer. At a fixed temperature, the field dependence of the time-logarithmic magnetic relaxation rate normalized to the first magnetization value, R=||d(M/M0)/d ln(t)||, was investigated in different polycrystalline HTSCs: TlBaCaCuO (2212 and 2223 single phases), YBaCuO (123 phase), and (Hg,Tl)BaCaCuO (1223 phase). The results obtained for TlBaCaCuO 2223 phase and (Hg,Tl)BaCaCuO show a common trend: R increases linearly with magnetic field up to a certain value, the dimensional crossover field H3D-2D, above which it becomes field-independent. H3D-2D is a characteristic field which depends on the anisotropy parameter and the interlayer spacing of the material. The field dependence of R can be ascribed to a crossover in the dimensionality of the object involved in the quantum process: above H3D-2D, the longitudinal dimension of the tunneling object, Lc, is smaller than the interlayer distance, so the object is of two-dimensional (2D) nature (2D pancake vortices). Below H3D-2D, 2D vortices in neighboring layers become coupled, so the tunneling object becomes three-dimensional (3D) in nature (3D flux-lines). The field dependences of R obtained for TlBaCaCuO 2212 phase and YBaCuO show only the 2D and 3D vortex regimes, respectively. Well agreement between theoretical estimates and experimental values for the dimensional crossover field and normalized relaxation rates is achieved. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362568
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  • 15
    Electronic Resource
    Electronic Resource
    Threading dislocations in silicon layer produced by separation by implanted oxygen process (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2113-2120 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Threading dislocations in the silicon layer in three different types of the silicon on insulator samples produced by standard and improved separation by implanted oxygen (SIMOX) processes were investigated by synchrotron x-ray topography, scanning electron microscopy (SEM), and optical microscopy. The densities and Burgers vectors of the dislocations were first determined nondestructively by synchrotron x-ray topography. Then the line directions of the same dislocations were determined by SEM after chemical Secco etching. Some of these results were compared with results obtained from optical microscopy of Secco etched samples. The threading dislocations in the Si layer were found to occur mainly in pairs with densities of the order of 105 cm−2 in standard SIMOX samples and of the order of 104 cm−2 in improved SIMOX samples. These dislocations have an edge character. Other features of these dislocations, such as the distances between two dislocations forming a pair, orientations of these pairs, and dislocations that change their line direction, are also discussed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363104
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  • 16
    Electronic Resource
    Electronic Resource
    Quantum vortex motion in high-Tc superconductors : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 6516-6518 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic relaxation experiments at low temperatures were performed in different zero-field-cooled (ZFC) and field-cooled (FC) high-Tc superconductors (HTSCs): TlBaCaCuO (2212 and 2223 phases, polycrystalline and thin-film samples), (Hg,Tl)BaCaCuO (1223 phase, polycrystalline material), and (Bi,Pb)SrCaCuO (2212 phase, single crystal). For each system and in the whole temperature range investigated, the relaxation curves obtained after both cooling processes are linear with the logarithm of time. The temperature dependence of the relaxation rate normalized to the first magnetization value, R=||d(M/M0)/d ln(t)||, follows a trend which is common to all systems: R decreases linearly with decreasing temperature down to a value, which is called the crossover temperature, below which it levels off to a T-independent plateau. This behavior gives evidence of a transition in the mechanism responsible for the relaxation process at low temperatures, from thermally activated (linear dependence on T) to quantum vortex motion (T-independent regime). The experimental values for the crossover temperatures and normalized relaxation rates compare fairly well to numerical estimates in the framework of the theories of quantum vortex motion in layered HTSCs. Finally, the transition from one regime into another was studied in two samples of the TlBaCaCuO, 2223 phase, system in order to investigate the influence of dissipation on the quantum process. A clear conclusion on this point could not be drawn from these kinds of measurements. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361930
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  • 17
    Electronic Resource
    Electronic Resource
    Intra-4f-shell transitions at room temperature of Er3+ ions in Ca1−xErxF2+x thin films grown on Si(100) (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 1133-1137 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Intra-4f-shell transitions of Er3+ ions in Ca1−xErxF2+x thin films were studied by means of photoluminescence (PL) and cathodoluminescence (CL) measurements at room temperature. The samples, with x varying from 0.01 to 0.2, were epitaxially grown on Si(100) substrates by sublimation of solid solution powders. Using the 488-nm line of an Ar+-ion laser as the excitation source, it is shown that the films present strong PL lines corresponding to the internal transitions between the 4S3/2,4F9/2,4I11/2, and 4I13/2 excited levels and the 4I15/2 fundamental state of Er3+ (4f11) ions. Their centers of gravity were pointed out at λ=533, 650, 980, and 1530 nm, respectively. These electronic transitions were also evidenced by means of the CL technique. Moreover, this technique showed that the luminescence is uniform in all points of the layers. The PL intensities vary considerably as a function of the erbium substitution rate. In the visible range the strongest luminescence was found for x less than 0.01, while for the 1530-nm line (which presents evident potential applications for optical communications) the highest luminescence intensity corresponds to x close to 0.16. The refractive index (n) of the layers also varies with the erbium concentration. For a 1.3-μm incident radiation, n continuously increases from 1.425 to 1.466 when x varies from 0.035 to 0.19. This result shows that these structures can lead to the realization of plane optical waveguides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356497
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  • 18
    Electronic Resource
    Electronic Resource
    Magnetization processes in samples with modulated anisotropy under the action of nonuniform magnetic fields (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 3961-3964 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we study the magnetic behavior of amorphous ferromagnetic ribbons having helical anisotropy with the helix axis perpendicular to the sample surface. It is shown that the magnetization processes under the action of a longitudinal magnetic field can be controlled by the nonuniform field produced by an alternating current, of the same frequency than the exciting field, flowing through the sample. Hysteresis loops with very different susceptibilities and coercive fields have been obtained by varying the amplitude of the current intensity and the phase differences between the exciting magnetic field and the current through the sample. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359917
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  • 19
    Electronic Resource
    Electronic Resource
    Large critical current densities in YBa2Cu3O7−x thin films made at high deposition rates (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 523-525 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Critical current densities (Jc) in YBa2Cu3O7−x films made at deposition rates from 0.1 to 14.5 nm/s (∼50 μm/h) were measured using a direct transport method. As the deposition rate was increased by two orders of magnitude, the films exhibited no marked degradation in current carrying capability with Jc of ∼4×106 A/cm2 at 77 K and zero field. Jc for all the films showed similar behavior under a magnetic field up to 8 T, although extra structural defects were found in the films deposited at the higher rates. The results from this experiment indicate the feasibility for coating wires, tapes, and other macroscopic shapes with high Tc superconductors using proper vapor deposition techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104245
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  • 20
    Electronic Resource
    Electronic Resource
    Epitaxial CeO2 films as buffer layers for high-temperature superconducting thin films (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2165-2167 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have prepared epitaxial (100)CeO2 thin films on LaAlO3, sapphire, and yttria-stabilized zirconia using pulsed laser deposition. It is demonstrated in this letter that the CeO2 films are chemically and structurally compatible to the high-temperature superconductor YBa2Cu3O7−δ (YBCO). Epitaxial YBCO films on CeO2/LaAlO3 had a zero resistance temperature and critical current density in a zero field of 90 K and 5.9×106 A/cm2 at 75 K, respectively. Furthermore, epitaxial multilayers of CeO2/YBCO were prepared. This work demonstrated that CeO2 is an excellent buffer layer material for the high-temperature superconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104994
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