7,284 research outputs found
Een proef ter bepaling van de werking van het chloride in stalmest op de zetmeelopbrengst van fabrieksaardappelen
Photoresponse of epitaxial YBa2Cu3O7-x ultrathin films
The voltage photoresponse of YBa2CH307_ x/SrTiO3 10 nm-tlfick films\ud
on laser irradiation is studied using the low temperature scanning laser\ud
microscopy (LTSLM) teclmique. The irradiation wavelength is 633 run.\ud
The spatial response dependencies via temperature (4-100 K), beam\ud
intensity modulation frequency (0-150 kHz) and bias current are\ud
examined. The bolometric and non-bolometric components are\ud
separated. The amplitude of the non-bolometric component at 4.2 K is\ud
about 10 times higher than that of bolometric one measured near the\ud
midpoint of the superconducting transition. The non-bolometric\ud
component is presumably associated with weak links in the film due to\ud
interdiffusion of SrTiO3 into YBCO layer. The spatial irregularity in\ud
superconducting parameters is not resolved by the LTSLM method\ud
since the spacing between weak links is appeared to be less than 1 um
Concordant HIV Infection and Visceral Leishmaniasis in Ethiopia: The Influence of Antiretroviral Treatment and Other Factors on Outcome
Electric-field effect devices made of YBa2Cu3O7-x/SrTiO3 epitaxial multilayers
Three terminal superconducting electric-field effect devices, consisting of a bufferlayer of PrBa2Cu3O7-x, an ultrathin layer of YBa2Cu3O7-x and a SrTiO3 gate isolation layer were fabricated and successfully operated. Transmission electron microscopy and laser scanning microscopy showed that all layers are highly epitaxial and uniform over the device area. This is essentially important in the analysis of the mechanism of the electric field effect and for the reproducible fabrication of devices. With a 5 nm thick YBa2Cu3O7-x layer and an applied electric field of 0.85 MV/cm the critical current was decreased by 5% at low temperatures and up to 36% close to Tc. Also enhancement was obtained
A HREM study of the atomic structure and the growth mechanism of the YBa2Cu3O7/YSZ interface
The interface between yttria-stabilized zirconia (YSZ) substrate and YBa2Cu3O7 (YBCO) film was studied by high-resolution electron microscopy. In all specimens we have observed an intermediate layer of BaZrO3 located between the substrate YSZ and YBCO. The BaZrO3 layer is composed of almost equally aligned domains being 4¿8 nm in the lateral directions. Reaction products such as Y and Cu oxides were never observed in or close to the BaZrO3 reaction layer but they do occur in the YBCO film. The stacking sequence of BaZrO3/YBCO is predominantly (BaZrO3)-ZrO2-BaO/CuO-BaO-(YBCO) with CuO layer as the beginning YBCO layer. Sometimes a stacking sequence (BaZrO3)-ZrO2-BaO/BaO-CuO2-(YBCO) with a BaO layer as the beginning YBCO layer was observed. This stacking is related to a dislocation with Burgers vector a'/2 [111], where a' = 0.42 nm is the lattice constant of the cubic BaZrO3. Three main epitaxial relations (0°, 45°, 9°) between YSZ and YBCO were observed. These can be explained by near-coincidence site lattices ¿ = 25, ¿ = 49 and ¿ = 13 (for a YSZ substrate). Usually the (001) plane of the YBCO film is parallel to the (001) plane of the BaZrO3 layer and parallel to the substrate surface. In case YBCO is grown on an inclined YSZ substrate, the (001) plane of the YBCO film is parallel to the substrate surface and thus not parallel to the (001) plane of the YSZ substrate
Formation of a penumbra in a decaying sunspot
Context : Penumbrae are an important characteristic of sunspots, whose
formation is intricately related to the nature of sub-photospheric magnetic
fields. Aims : We study the formation of a penumbra in a decaying sunspot and
compare its properties with those seen during the development of a proto-spot.
Methods : High-resolution spectropolarimetric observations of active region
NOAA 11283 were obtained from the spectro-polarimeter on board Hinode. These
were complemented with full-disk filtergrams of continuum intensity,
line-of-sight magnetograms, and dopplergrams from the Helioseismic and Magnetic
Imager at high cadence. Results : The formation of a penumbra in the decaying
sunspot occurs after the coalescence of the sunspot with a magnetic
fragment/pore, which initially formed in the quiet Sun close to an emerging
flux region. At first, a smaller set of penumbral filaments develop near the
location of the merger with very bright penumbral grains with intensities of
1.2 I_QS, upflows of 4 km/s, and a lifetime of 10 hr. During the decay of these
filaments, a larger segment of a penumbra forms at the location of the
coalescence. These new filaments are characterized by nearly supersonic
downflows of 6.5 km/s that change to a regular Evershed flow nearly 3 hr later.
Conclusions : The coalescence of the pore with the decaying sunspot provided
sufficient magnetic flux for the penumbra to form in the sunspot. The emerging
flux region could have played a decisive role in this process because the
formation occurred at the location of the merger and not on the opposite side
of the sunspot.Comment: Accepted for publication in A&A Letters, 6 pages, 4 figure
A new result on the Klein-Gordon equation in the background of a rotating black hole
This short paper should serve as basis for further analysis of a previously
found new symmetry of the solutions of the wave equation in the gravitational
field of a Kerr black hole. Its main new result is the proof of essential
self-adjointness of the spatial part of a reduced normalized wave operator of
the Kerr metric in a weighted L^2-space. As a consequence, it leads to a purely
operator theoretic proof of the well-posedness of the initial value problem of
the reduced Klein-Gordon equation in that field in that L^2-space and in this
way generalizes a corresponding result of Kay (1985) in the case of the
Schwarzschild black hole. It is believed that the employed methods are
applicable to other separable wave equations
Probing the density dependence of the symmetry potential in intermediate energy heavy ion collisions
Based on the ultrarelativistic quantum molecular dynamics (UrQMD) model, the effects of the density-dependent symmetry potential for baryons and of the Coulomb potential for produced mesons are investigated for neutron-rich heavy ion collisions at intermediate energies. The calculated results of the Delta-/Delta++ and pi -/pi + production ratios show a clear beam-energy dependence on the density-dependent symmetry potential, which is stronger for the pi -/pi + ratio close to the pion production threshold. The Coulomb potential of the mesons changes the transverse momentum distribution of the pi -/pi + ratio significantly, though it alters only slightly the pi- and pi+ total yields. The pi- yields, especially at midrapidity or at low transverse momenta and the p-/pi+ ratios at low transverse momenta, are shown to be sensitive probes of the density-dependent symmetry potential in dense nuclear matter. The effect of the density-dependent symmetry potential on the production of both, K0 and K+ mesons, is also investigated
Proef over de effecten van stikstof, kalium en chloride op de zetmeelopbrengst van fabrieksaardappelen
- …