280 research outputs found
Flexible and robust networks
We consider networks with two types of nodes. The v-nodes, called centers,
are hyper- connected and interact one to another via many u-nodes, called
satellites. This central- ized architecture, widespread in gene networks,
possesses two fundamental properties. Namely, this organization creates
feedback loops that are capable to generate practically any prescribed
patterning dynamics, chaotic or periodic, or having a number of equilib- rium
states. Moreover, this organization is robust with respect to random
perturbations of the system.Comment: Journal of Bioinformatics and Computational Biology, in pres
Toroidal Soliton Solutions in O(3)^N Nonlinear Sigma Model
A set of N three component unit scalar fields in (3+1) Minkowski space-time
is investigated. The highly nonlinear coupling between them is chosen to omit
the scaling instabilities. The multi-soliton static configurations with
arbitrary Hopf numbers are found. Moreover, the generalized version of the
Vakulenko-Kapitansky inequality is obtained. The possibility of attractive,
repulsing and noninteracting channels is discussed.Comment: to be published in Mod. Phys. Lett.
Glueball mass from quantized knot solitons and gauge-invariant gluon mass
We propose an approach which enables one to obtain simultaneously the
glueball mass and the gluon mass in the gauge-invariant way to shed new light
on the mass gap problem in Yang-Mills theory. First, we point out that the
Faddeev (Skyrme--Faddeev-Niemi) model can be induced through the
gauge-invariant vacuum condensate of mass dimension two from SU(2) Yang-Mills
theory. Second, we obtain the glueball mass spectrum by performing the
collective coordinate quantization of the topological knot soliton in the
Faddeev model. Third, we demonstrate that a relationship between the glueball
mass and the gluon mass is obtained, since the gauge-invariant gluon mass is
also induced from the relevant vacuum condensate. Finally, we determine
physical values of two parameters in the Faddeev model and give an estimate of
the relevant vacuum condensation in Yang-Mills theory. Our results indicate
that the Faddeev model can play the role of a low-energy effective theory of
the quantum SU(2) Yang-Mills theory.Comment: 17 pages, 2 figures, 3 tables; a version accepted for publication in
J. Phys. A: Math. Gen.; Sect. 2 and sect. 5 (old sect. 4) are modified. Sect.
4, Tables 1 and Table 3 are adde
The influence of environmental forcing on biodiversity and extinction in a resource competition model
In this paper, we study a model of many species that compete, directly or indirectly, for a pool of common resources under the influence of periodic, stochastic, and/or chaotic environmental forcing. Using numerical simulations, we find the number and sequence of species going extinct when the community is initially packed with a large number of species of random initial densities. Thereby, any species with a density below a given threshold is regarded to be extinct
Soliton in Gravitating Gas. Hoag's Object
We explore the possibility of creating of solitons in gravitating gas. It is
shown that the virial arguments does not put an obstacle for the existence of
localized static solutions. The simplest toroidal soliton of gravitating gas
could be the explanation of the peculiar galaxy named Hoag's object.Comment: 14 pages, 1 Figur
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