5,278 research outputs found
Pressure test analysis of 200-inch multicell test tank
Pressure test analysis for large multiple cell tank with sectioned ski
Recovery of the biological activity in a vineyard soil after landscape redesign: A three-year study using the bait-lamina method
To detect changes in the biological activity (checked as soil animals feeding activity), the bait-lamina test (VON TÖRNE 1990) was used in a vineyard and a fallow soil (old meadow) during a three-year study. Situated in the vine-growing region of Rheinhessen near Mainz, Germany, the vineyard was part of an intensive redesign of the landscape accompanied by soil restoration. In 1994 new grapevines were planted in a two-row-system: 1) uncovered, 'open' soil, 2) green-covered soil (grass and clover). The new vineyard soil was in a 'raw' soil stage (humus: <1.7 %) whereas the fallow soil (reference soil) was undisturbed (humus: approx. 5 %). At the onset of the experiment in spring 1997 the soil faunal feeding activity in the vineyard soil was close to zero while in the fallow soil the activity was 23 %. In the following tests the feeding activity increased in both, the green-covered and uncovered soil; the highest level of feeding activity was finally found in the covered soil. The results indicate that under the local climatic conditions soil faunal activity recovers within a few years after soil restoration and that the rate of biological activity depends on soil management
Subtropical Real Root Finding
We describe a new incomplete but terminating method for real root finding for
large multivariate polynomials. We take an abstract view of the polynomial as
the set of exponent vectors associated with sign information on the
coefficients. Then we employ linear programming to heuristically find roots.
There is a specialized variant for roots with exclusively positive coordinates,
which is of considerable interest for applications in chemistry and systems
biology. An implementation of our method combining the computer algebra system
Reduce with the linear programming solver Gurobi has been successfully applied
to input data originating from established mathematical models used in these
areas. We have solved several hundred problems with up to more than 800000
monomials in up to 10 variables with degrees up to 12. Our method has failed
due to its incompleteness in less than 8 percent of the cases
Swift J053041.9-665426, a new Be/X-ray binary pulsar in the Large Magellanic Cloud
We observed the newly discovered X-ray source Swift J053041.9-665426 in the
X-ray and optical regime to confirm its proposed nature as a high mass X-ray
binary. We obtained XMM-Newton and Swift X-ray data, along with optical
observations with the ESO Faint Object Spectrograph, to investigate the
spectral and temporal characteristics of Swift J053041.9-665426. The XMM-Newton
data show coherent X-ray pulsations with a period of 28.77521(10) s (1 sigma).
The X-ray spectrum can be modelled by an absorbed power law with photon index
within the range 0.76 to 0.87. The addition of a black body component increases
the quality of the fit but also leads to strong dependences of the photon
index, black-body temperature and absorption column density. We identified the
only optical counterpart within the error circle of XMM-Newton at an angular
distance of ~0.8 arcsec, which is 2MASS J05304215-6654303. We performed optical
spectroscopy from which we classify the companion as a B0-1.5Ve star. The X-ray
pulsations and long-term variability, as well as the properties of the optical
counterpart, confirm that Swift J053041.9-665426 is a new Be/X-ray binary
pulsar in the Large Magellanic Cloud.Comment: 10 pages, 8 figures, accepted for publication in A&
High-ionization mid-infrared lines as black hole mass and bolometric luminosity indicators in active galactic nuclei
We present relations of the black hole mass and the optical luminosity with
the velocity dispersion and the luminosity of the [Ne V] and the [O IV]
high-ionization lines in the mid-infrared (MIR) for 28 reverberation-mapped
active galactic nuclei. We used high-resolution Spitzer Infrared Spectrograph
and Infrared Space Observatory Short Wavelength Spectrometer data to fit the
profiles of these MIR emission lines that originate from the narrow-line region
of the nucleus. We find that the lines are often resolved and that the velocity
dispersion of [Ne V] and [O IV] follows a relation similar to that between the
black hole mass and the bulge stellar velocity dispersion found for local
galaxies. The luminosity of the [Ne V] and the [O IV] lines in these sources is
correlated with that of the optical 5100A continuum and with the black hole
mass. Our results provide a means to derive black hole properties in various
types of active galactic nuclei, including highly obscured systems.Comment: accepted for publication in ApJ
The XMM-Newton view of the central degrees of the Milky Way
The deepest XMM-Newton mosaic map of the central 1.5 deg of the Galaxy is
presented, including a total of about 1.5 Ms of EPIC-pn cleaned exposures in
the central 15" and about 200 ks outside. This compendium presents broad-band
X-ray continuum maps, soft X-ray intensity maps, a decomposition into spectral
components and a comparison of the X-ray maps with emission at other
wavelengths. Newly-discovered extended features, such as supernova remnants
(SNRs), superbubbles and X-ray filaments are reported. We provide an atlas of
extended features within +-1 degree of Sgr A*. We discover the presence of a
coherent X-ray emitting region peaking around G0.1-0.1 and surrounded by the
ring of cold, mid-IR-emitting material known from previous work as the "Radio
Arc Bubble" and with the addition of the X-ray data now appears to be a
candidate superbubble. Sgr A's bipolar lobes show sharp edges, suggesting that
they could be the remnant, collimated by the circumnuclear disc, of a SN
explosion that created the recently discovered magnetar, SGR J1745-2900. Soft
X-ray features, most probably from SNRs, are observed to fill holes in the dust
distribution, and to indicate a direct interaction between SN explosions and
Galactic center (GC) molecular clouds. We also discover warm plasma at high
Galactic latitude, showing a sharp edge to its distribution that correlates
with the location of known radio/mid-IR features such as the "GC Lobe". These
features might be associated with an inhomogeneous hot "atmosphere" over the
GC, perhaps fed by continuous or episodic outflows of mass and energy from the
GC region.Comment: MNRAS published online. See www.mpe.mpg.de/heg/gc/ for a higher
resolution version of the figure
Simple test for quantum channel capacity
Basing on states and channels isomorphism we point out that semidefinite
programming can be used as a quick test for nonzero one-way quantum channel
capacity. This can be achieved by search of symmetric extensions of states
isomorphic to a given quantum channel. With this method we provide examples of
quantum channels that can lead to high entanglement transmission but still have
zero one-way capacity, in particular, regions of symmetric extendibility for
isotropic states in arbitrary dimensions are presented. Further we derive {\it
a new entanglement parameter} based on (normalised) relative entropy distance
to the set of states that have symmetric extensions and show explicitly the
symmetric extension of isotropic states being the nearest to singlets in the
set of symmetrically extendible states. The suitable regularisation of the
parameter provides a new upper bound on one-way distillable entanglement.Comment: 6 pages, no figures, RevTeX4. Signifficantly corrected version. Claim
on continuity of channel capacities removed due to flaw in the corresponding
proof. Changes and corrections performed in the part proposing a new upper
bound on one-way distillable etanglement which happens to be not one-way
entanglement monoton
On the connection between the number of nodal domains on quantum graphs and the stability of graph partitions
Courant theorem provides an upper bound for the number of nodal domains of
eigenfunctions of a wide class of Laplacian-type operators. In particular, it
holds for generic eigenfunctions of quantum graph. The theorem stipulates that,
after ordering the eigenvalues as a non decreasing sequence, the number of
nodal domains of the -th eigenfunction satisfies . Here,
we provide a new interpretation for the Courant nodal deficiency in the case of quantum graphs. It equals the Morse index --- at a
critical point --- of an energy functional on a suitably defined space of graph
partitions. Thus, the nodal deficiency assumes a previously unknown and
profound meaning --- it is the number of unstable directions in the vicinity of
the critical point corresponding to the -th eigenfunction. To demonstrate
this connection, the space of graph partitions and the energy functional are
defined and the corresponding critical partitions are studied in detail.Comment: 22 pages, 6 figure
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