939 research outputs found
Random Sierpinski network with scale-free small-world and modular structure
In this paper, we define a stochastic Sierpinski gasket, on the basis of
which we construct a network called random Sierpinski network (RSN). We
investigate analytically or numerically the statistical characteristics of RSN.
The obtained results reveal that the properties of RSN is particularly rich, it
is simultaneously scale-free, small-world, uncorrelated, modular, and maximal
planar. All obtained analytical predictions are successfully contrasted with
extensive numerical simulations. Our network representation method could be
applied to study the complexity of some real systems in biological and
information fields.Comment: 7 pages, 9 figures; final version accepted for publication in EPJ
Electronic States in Two-Dimensional Triangular Cobalt Oxides: Role of Electronic Correlation
We obtain the electronic states and structures of two-dimensional cobalt
oxides, NaCoO (x=0, 0.35, 0.5 and 0.75) by utilizing the
full-potential linear muffin-tin orbitals (FP-LMTO) methods, from which some
essential electronic interaction parameters are estimated: the bare on-site
Coulomb interaction of cobalt U=7.5 eV renormalizes to 5 eV for x=0.35,
the hybridizations t and t are -1.40 and 0.70 eV,
respectively. The density of states at E decreases from 6-7 states/eV in
the local density approximation (LDA) to about 1.0 states/eV in the LDA+U
scheme. The role of the intercalation of water molecules and the microscopic
mechanism of the superconductivity in NaCoOmHO is
discussed.Comment: minor errors correcte
The discovery and comparative expression analysis of three distinct type I interferons in the perciform fish, meagre (Argyrosomus regius)
Type I interferons (IFN) play an important role in anti-viral responses. In teleost fish multiple genes exist, that are classified by group/subgroup. That multiple subgroups are present in Acanthopterygian fish has only become apparent recently, and 3 subgroups are now known to be expressed, including a new subgroup termed IFNh. However, the potential to express multiple IFN subgroups and their interplay is not well defined. Hence this study aims to clarify the situation and undertook the first in-depth analysis into the nature and expression of IFNc, IFNd and IFNh in the perciform fish, meagre. Constitutive expression was analysed initially during larval development and in adult tissues (gills, mid-gut, head kidney, spleen). During early ontogeny IFNc was the highest expressed IFN, and this was also the case in adult tissues with the exception of gills where IFNd was highest. However, comparison between tissues for individual isoforms showed that spleen had high transcript levels of all three IFNs, IFNd/IFNh were also highly expressed in gills. The expression of each sub-group was increased significantly in the four tissues following injection of poly I:C, however, this increase was only seen in the mid-gut for IFNh. Following in vitro stimulation with poly I:C again all three isoforms were upregulated, although with differences in kinetics and the cell source used. For example, early induction was seen for IFNc/IFNh in gill cells, IFNd/IFNh in splenocytes and all three isoforms in head kidney cells. Induction was sustained in splenocytes and head kidney cells, but in gut cells only a late induction was seen. These results demonstrate a complex pattern of regulation between the different IFN isoforms present in meagre and highlights potential sub-functionalisation of these IFN subgroups during perciform anti-viral responses.info:eu-repo/semantics/acceptedVersio
Onset of magnetism in B2 transition metals aluminides
Ab initio calculation results for the electronic structure of disordered bcc
Fe(x)Al(1-x) (0.4<x<0.75), Co(x)Al(1-x) and Ni(x)Al(1-x) (x=0.4; 0.5; 0.6)
alloys near the 1:1 stoichiometry, as well as of the ordered B2 (FeAl, CoAl,
NiAl) phases with point defects are presented. The calculations were performed
using the coherent potential approximation within the Korringa-Kohn-Rostoker
method (KKR-CPA) for the disordered case and the tight-binding linear
muffin-tin orbital (TB-LMTO) method for the intermetallic compounds. We studied
in particular the onset of magnetism in Fe-Al and Co-Al systems as a function
of the defect structure. We found the appearance of large local magnetic
moments associated with the transition metal (TM) antisite defect in FeAl and
CoAl compounds, in agreement with the experimental findings. Moreover, we found
that any vacancies on both sublattices enhance the magnetic moments via
reducing the charge transfer to a TM atom. Disordered Fe-Al alloys are
ferromagnetically ordered for the whole range of composition studied, whereas
Co-Al becomes magnetic only for Co concentration >0.5.Comment: 11 pages with 9 embedded postscript figures, to be published in
Phys.Rev.
Investigating the topology of interacting networks - Theory and application to coupled climate subnetworks
Network theory provides various tools for investigating the structural or
functional topology of many complex systems found in nature, technology and
society. Nevertheless, it has recently been realised that a considerable number
of systems of interest should be treated, more appropriately, as interacting
networks or networks of networks. Here we introduce a novel graph-theoretical
framework for studying the interaction structure between subnetworks embedded
within a complex network of networks. This framework allows us to quantify the
structural role of single vertices or whole subnetworks with respect to the
interaction of a pair of subnetworks on local, mesoscopic and global
topological scales.
Climate networks have recently been shown to be a powerful tool for the
analysis of climatological data. Applying the general framework for studying
interacting networks, we introduce coupled climate subnetworks to represent and
investigate the topology of statistical relationships between the fields of
distinct climatological variables. Using coupled climate subnetworks to
investigate the terrestrial atmosphere's three-dimensional geopotential height
field uncovers known as well as interesting novel features of the atmosphere's
vertical stratification and general circulation. Specifically, the new measure
"cross-betweenness" identifies regions which are particularly important for
mediating vertical wind field interactions. The promising results obtained by
following the coupled climate subnetwork approach present a first step towards
an improved understanding of the Earth system and its complex interacting
components from a network perspective
Existence and uniqueness of solutions for systems of fractional differential equations with Riemann–Stieltjes integral boundary condition
In this article, we first establish an existence and uniqueness result for a class of systems of nonlinear operator equations under more general conditions by means of the cone theory and monotone iterative technique. Furthermore, the iterative sequence of the solution and the error estimation of the system are given. Then we use this new result to study the existence and uniqueness of the solution for boundary value problems of systems of fractional differential equations with a Riemann–Stieltjes integral boundary condition in real Banach spaces. The results obtained in this paper are more general than many previous results and complement them
О неустойчивости решений динамических уравнений на временной шкале
В роботi наведено результати аналiзу нестiйкостi динамiчних рiвнянь на часовiй шкалi. Застосовнiсть отриманого результату iлюструється на прикладi системи другого порядку.We present new results on the instability for dynamic equations on time scales. To demonstrate the applicability, we use some examples of dynamic equations of the second order
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