8,508 research outputs found
Satellite detection of vegetative damage and alteration caused by pollutants emitted by a zinc smelter
The author has identified the following significant results. Field observations and data collected by low flying aircraft were used to verify the accuracy of maps produced from the satellite data. Although areas of vegetation as small as six acres can accurately be detected, a white pine stand that was severely damaged by sulfur dioxide could not be differentiated from a healthy white pine stand because spectral differences were not large enough. When winter data were used to eliminate interference from herbaceous and deciduous vegetation, the damage was still undetectable. The analysis was able to produce a character map that accurately delineated areas of vegetative alteration due to high zinc levels accumulating in the soil. The map depicted a distinct gradient of less damage and alteration as the distance from the smelter increased. Although the satellite data will probably not be useful for detecting small acreages of damaged vegetation, it is concluded that the data may be very useful as an inventory tool to detect and delineate large vegetative areas possessing differing spectral signatures
Correlating the nanostructure of Al-oxide with deposition conditions and dielectric contributions of two-level systems in perspective of superconducting quantum circuits
This work is concerned with Al/Al-oxide(AlO)/Al-layer systems which are
important for Josephson-junction-based superconducting devices such as quantum
bits. The device performance is limited by noise, which has been to a large
degree assigned to the presence and properties of two-level tunneling systems
in the amorphous AlO tunnel barrier. The study is focused on the
correlation of the fabrication conditions, nanostructural and nanochemical
properties and the occurrence of two-level tunneling systems with particular
emphasis on the AlO-layer. Electron-beam evaporation with two different
processes and sputter deposition were used for structure fabrication, and the
effect of illumination by ultraviolet light during Al-oxide formation is
elucidated. Characterization was performed by analytical transmission electron
microscopy and low-temperature dielectric measurements. We show that the
fabrication conditions have a strong impact on the nanostructural and
nanochemical properties of the layer systems and the properties of two-level
tunneling systems. Based on the understanding of the observed structural
characteristics, routes are derived towards the fabrication of
Al/AlO/Al-layers systems with improved properties.Comment: 28 pages, 4 figure
Tsirelson's problem and Kirchberg's conjecture
Tsirelson's problem asks whether the set of nonlocal quantum correlations
with a tensor product structure for the Hilbert space coincides with the one
where only commutativity between observables located at different sites is
assumed. Here it is shown that Kirchberg's QWEP conjecture on tensor products
of C*-algebras would imply a positive answer to this question for all bipartite
scenarios. This remains true also if one considers not only spatial
correlations, but also spatiotemporal correlations, where each party is allowed
to apply their measurements in temporal succession; we provide an example of a
state together with observables such that ordinary spatial correlations are
local, while the spatiotemporal correlations reveal nonlocality. Moreover, we
find an extended version of Tsirelson's problem which, for each nontrivial Bell
scenario, is equivalent to the QWEP conjecture. This extended version can be
conveniently formulated in terms of steering the system of a third party.
Finally, a comprehensive mathematical appendix offers background material on
complete positivity, tensor products of C*-algebras, group C*-algebras, and
some simple reformulations of the QWEP conjecture.Comment: 57 pages, to appear in Rev. Math. Phy
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Shock recovery experiments confirm the possibility of transferring viable microorganisms from Mars to Earth
Extract from introduction: With regard to the impact and ejection phase we tested the case for the transfer of microorganisms from Mars to Earth. Using a high explosive set-up thin layers of bacterial endospores of Bacillus subtilis, of the lichen Xanthoria elegans and of the cyanobacterium Chroococcidiopsis sp. embedded between two plates of gabbro were subjected to 10, 20, 30, 40 and 50 GPa which is the pressure range observed in Martian meteorites [1]
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Life after shock: the mission from Mars to Earth
Extract from introduction: The minerals of the Martian meteorites collected so far indicate an exposure to shock waves in the pressure range of 5 to 55 GPa [1]. As terrestrial rocks are frequently inhabited by microbial communities, rocks ejected from a planet by impact processes may carry with them endolithic microorganisms, if microbial life existed/exists on this planet
Quantification of myeloperoxidase from human granulocytes as an inflammation marker by enzyme.linked immunosorbent assay
HERschel Observations of Edge-on Spirals (HEROES). II: Tilted-ring modelling of the atomic gas disks
Context. Edge-on galaxies can offer important insights in galaxy evolution as
they are the only systems where the distribution of the different components
can be studied both radially and vertically. The HEROES project was designed to
investigate the interplay between the gas, dust, stars and dark matter (DM) in
a sample of 7 massive edge-on spiral galaxies.
Aims. In this second HEROES paper we present an analysis of the atomic gas
content of 6 out of 7 galaxies in our sample. The remaining galaxy was recently
analysed according to the same strategy. The primary aim of this work is to
constrain the surface density distribution, the rotation curve and the geometry
of the gas disks in a homogeneous way. In addition we identify peculiar
features and signs of recent interactions.
Methods. We construct detailed tilted-ring models of the atomic gas disks
based on new GMRT 21-cm observations of NGC 973 and UGC 4277 and re-reduced
archival HI data of NGC 5907, NGC 5529, IC 2531 and NGC 4217. Potential
degeneracies between different models are resolved by requiring a good
agreement with the data in various representations of the data cubes.
Results. From our modelling we find that all but one galaxy are warped along
the major axis. In addition, we identify warps along the line of sight in three
galaxies. A flaring gas layer is required to reproduce the data only for one
galaxy, but (moderate) flares cannot be ruled for the other galaxies either. A
coplanar ring-like structure is detected outside the main disk of NGC 4217,
which we suggest could be the remnant of a recent minor merger event. We also
find evidence for a radial inflow of 15 +- 5 km/s in the disk of NGC 5529,
which might be related to the ongoing interaction with two nearby companions.
(Abridged)Comment: 39 pages, 38 figures, Accepted for publication in Astronomy &
Astrophysic
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