1,738 research outputs found
Self-organized criticality in a model of collective bank bankruptcies
The question we address here is of whether phenomena of collective
bankruptcies are related to self-organized criticality. In order to answer it
we propose a simple model of banking networks based on the random directed
percolation. We study effects of one bank failure on the nucleation of
contagion phase in a financial market. We recognize the power law distribution
of contagion sizes in 3d- and 4d-networks as an indicator of SOC behavior. The
SOC dynamics was not detected in 2d-lattices. The difference between 2d- and
3d- or 4d-systems is explained due to the percolation theory.Comment: For Int. J. Mod. Phys. C 13, No. 3, six pages including four figure
Ultra Luminous X-ray sources - new distance indicators?
In this paper we fit the NuSTAR and XMM-Newton data of three sources:
NGC7793~P13, NGC5907~ULX1, and Circinus~ULX5. Our single model contains
emission form non-spherical system: neutron star plus accretion disk directed
towards observer. We obtained the very good fit with the reduced per
degree of freedom equal 1.08 for P13, 1.01 for ULX1, and 1.14 for ULX5.The
normalization of our model constrains the distance to the source. The resulting
distances are , and
~Mpc for P13, ULX1 and ULX5 respectively. The distances
to P13 and ULX5 are in perfect agreement with previous distance measurements to
their host galaxies. Our results confirm that P13, ULX1 and ULX5 may contain
central hot neutron star. When the outgoing emission is computed by integration
over the emitting surface and successfully fitted to the data, then the
resulting model normalization is the direct distance indicator.Comment: 5 pages, 3 figures, accepted for publication in A&A Letter
Spatial distribution of soil water repellency in a grassland located in Lithuania
Soil water repellency (SWR) it is recognized to be very heterogeneous in time in space and depends on soil
type, climate, land use, vegetation and season (Doerr et al., 2002). It prevents or reduces water infiltration, with
important impacts on soil hydrology, influencing the mobilization and transport of substances into the soil profile.
The reduced infiltration increases surface runoff and soil erosion. SWR reduce also the seed emergency and
plant growth due the reduced amount of water in the root zone. Positive aspects of SWR are the increase of soil
aggregate stability, organic carbon sequestration and reduction of water evaporation (Mataix-Solera and Doerr,
2004; Diehl, 2013). SWR depends on the soil aggregate size. In fire affected areas it was founded that SWR was
more persistent in small size aggregates (Mataix-Solera and Doerr, 2004; Jordan et al., 2011). However, little
information is available about SWR spatial distribution according to soil aggregate size. The aim of this work
is study the spatial distribution of SWR in fine earth (<2 mm) and different aggregate sizes, 2-1 mm, 1-0.5 mm,
0.5-0.25 mm and <0.25 mm. The studied area is located near Vilnius (Lithuania) at 54 42ā N, 25 08 E, 158
masl. A plot with 400 m2 (20 x 20 m with 5 m space between sampling points) and 25 soil samples were collected
in the top soil (0-5 cm) and taken to the laboratory. Previously to SWR assessment, the samples were air dried.
The persistence of SWR was analysed according to the Water Drop Penetration Method, which involves placing
three drops of distilled water onto the soil surface and registering the time in seconds (s) required for the drop
complete penetration (Wessel, 1988). Data did not respected Gaussian distribution, thus in order to meet normality
requirements it was log-normal transformed. Spatial interpolations were carried out using Ordinary Kriging. The
results shown that SWR was on average in fine earth 2.88 s (Coeficient of variation % (CV%)=44.62), 2-1mm
1.73 s (CV%=45.10), 1-0.5 mm 2.02 s (CV%=93.75), 0.5-0.25 mm 3.12 s (CV%=233.68) and in <0.25 mm 15.54
mm (CV%=240.74). This suggests that SWR persistence and CV% is higher in small size aggregates than in the
coarser aggregate sizes. The interpolated maps showed that in fine earth SWR was higher in the western part of
the studied plot and lower in the central area. In the 2-1 mm aggregate size it was higher in the southwest and
lower at north and northwest area. In the 1-0.5 mm aggregate size it was lower in the central area and higher in the
southwest. In the 0.5-0.25 mm aggregate size it was higher in the west part and lower in the north of the plot and.
In the <0.25 mm no specific pattern was identified and the SWR was heterogeneously distributed. This suggests
that the spatial distribution of SWR is very different according to the aggregate size. Future studies are needed in
order to identify the causes and consequences of such dynamic.
Acknowledgements
The authors appreciated the support of the project āLitfireā, Fire effects in Lithuanian soils and ecosystems
(MIP-048/2011) funded by the Lithuanian Research Counci
On the Intermediate Line Region in AGNs
In this paper we explore the intermediate line region (ILR) by using the
photoionisation simulations of the gas clouds present at different radial
distances from the center, corresponding to the locations from BLR out to NLR
in four types of AGNs. We let for the presence of dust whenever conditions
allow for dust existence. All spectral shapes are taken from the recent
multi-wavelength campaigns. The cloud density decreases with distance as a
power law. We found that the slope of the power law density profile does not
affect the line emissivity radial profiles of major emission lines: H,
He~II, Mg~II, C~III] ~and [O~III]. When the density of the cloud at the
sublimation radius is as high as 10 cm, the ILR should clearly
be seen in the observations independently of the shape of the illuminating
radiation. Moreover, our result is valid for low ionization nuclear emission
regions of active galaxies.Comment: 8 pages, 2 figures, Accepted for publication in the Journal Frontiers
in Astronomy and Space Science
Analysis of complete positivity conditions for quantum qutrit channels
We present an analysis of complete positivity (CP) constraints on qutrit
quantum channels that have a form of affine transformations of generalized
Bloch vector. For diagonal (damping) channels we derive conditions analogous to
the ones that in qubit case produce tetrahedron structure in the channel
parameter space.Comment: 12 pages, 8 figures (.eps), minor changes in the text and formula
The prime spectrum of algebras of quadratic growth
We study prime algebras of quadratic growth. Our first result is that if
is a prime monomial algebra of quadratic growth then has finitely many
prime ideals such that has GK dimension one. This shows that prime
monomial algebras of quadratic growth have bounded matrix images. We next show
that a prime graded algebra of quadratic growth has the property that the
intersection of the nonzero prime ideals such that has GK dimension 2
is non-empty, provided there is at least one such ideal. From this we conclude
that a prime monomial algebra of quadratic growth is either primitive or has
nonzero locally nilpotent Jacobson radical. Finally, we show that there exists
a prime monomial algebra of GK dimension two with unbounded matrix images
and thus the quadratic growth hypothesis is necessary to conclude that there
are only finitely many prime ideals such that has GK dimension 1.Comment: 23 page
- ā¦