340 research outputs found
Traffic on complex networks: Towards understanding global statistical properties from microscopic density fluctuations
We study the microscopic time fluctuations of traffic load and the global statistical properties of a dense traffic of particles on scale-free cyclic graphs. For a wide range of driving rates R the traffic is stationary and the load time series exhibits antipersistence due to the regulatory role of the superstructure associated with two hub nodes in the network. We discuss how the superstructure affects the functioning of the network at high traffic density and at the jamming threshold. The degree of correlations systematically decreases with increasing traffic density and eventually disappears when approaching a jamming density Rc. Already before jamming we observe qualitative changes in the global network-load distributions and the particle queuing times. These changes are related to the occurrence of temporary crises in which the network-load increases dramatically, and then slowly falls back to a value characterizing free flow
Disorder-induced critical behavior in driven diffusive systems
Using dynamic renormalization group we study the transport in driven
diffusive systems in the presence of quenched random drift velocity with
long-range correlations along the transport direction. In dimensions
we find fixed points representing novel universality classes of
disorder-dominated self-organized criticality, and a continuous phase
transition at a critical variance of disorder. Numerical values of the scaling
exponents characterizing the distributions of relaxation clusters are in good
agreement with the exponents measured in natural river networks
Graphene membrane as a pressure gauge
Straining graphene results in the appearance of a pseudo-magnetic field which
alters its local electronic properties. Applying a pressure difference between
the two sides of the membrane causes it to bend/bulge resulting in a resistance
change. We find that the resistance changes linearly with pressure for bubbles
of small radius while the response becomes non-linear for bubbles that stretch
almost to the edges of the sample. This is explained as due to the strong
interference of propagating electronic modes inside the bubble. Our
calculations show that high gauge factors can be obtained in this way which
makes graphene a good candidate for pressure sensing.Comment: 5 pages, 4 figure
Scaling of avalanche queues in directed dissipative sandpiles
We simulate queues of activity in a directed sandpile automaton in 1+1
dimensions by adding grains at the top row with driving rate .
The duration of elementary avalanches is exactly described by the distribution
, limited either by the system size or by
dissipation at defects . Recognizing the probability
as a distribution of service time of jobs arriving at a server with frequency
, the model represents a new example of the server
queue in the queue theory. We study numerically and analytically the tail
behavior of the distributions of busy periods and energy dissipated in the
queue and the probability of an infinite queue as a function of driving rate.Comment: 11 pages, 9 figures; To appear in Phys. Rev.
Finite driving rates in interface models of Barkhausen noise
We consider a single-interface model for the description of Barkhausen noise
in soft ferromagnetic materials. Previously, the model had been used only in
the adiabatic regime of infinitely slow field ramping. We introduce finite
driving rates and analyze the scaling of event sizes and durations for
different regimes of the driving rate. Coexistence of intermittency, with
non-trivial scaling laws, and finite-velocity interface motion is observed for
high enough driving rates. Power spectra show a decay , with
for finite driving rates, revealing the influence of the internal
structure of avalanches.Comment: 7 pages, 6 figures, RevTeX, final version to be published in Phys.
Rev.
Scale-free energy dissipation and dynamic phase transition in stochastic sandpiles
We study numerically scaling properties of the distribution of cumulative
energy dissipated in an avalanche and the dynamic phase transition in a
stochastic directed cellular automaton [B. Tadi\'c and D. Dhar, Phys. Rev.
Lett. {\bf 79}, 1519 (1997)] in d=1+1 dimensions. In the critical steady state
occurring for the probability of toppling = 0.70548, the
dissipated energy distribution exhibits scaling behavior with new scaling
exponents and D_E for slope and cut-off energy, respectively,
indicating that the sandpile surface is a fractal. In contrast to avalanche
exponents, the energy exponents appear to be p- dependent in the region
, however the product remains universal. We
estimate the roughness exponent of the transverse section of the pile as . Critical exponents characterizing the dynamic phase transition
at are obtained by direct simulation and scaling analysis of the
survival probability distribution and the average outflow current. The
transition belongs to a new universality class with the critical exponents
, and , with apparent violation of hyperscaling. Generalized hyperscaling
relation leads to , where is the exponent governed by the ultimate survival
probability
Global Jacquet-Langlands correspondence, multiplicity one and classification of automorphic representations
In this paper we show a local Jacquet-Langlands correspondence for all
unitary irreducible representations. We prove the global Jacquet-Langlands
correspondence in characteristic zero. As consequences we obtain the
multiplicity one and strong multiplicity one theorems for inner forms of GL(n)
as well as a classification of the residual spectrum and automorphic
representations in analogy with results proved by Moeglin-Waldspurger and
Jacquet-Shalika for GL(n).Comment: 49 pages; Appendix by N. Grba
Mathematical-geographical analysis of the orientation of St John's church of the Studenica monastery
Considering the fact that ecclesiastical rules do not precisely say that a church must be directed 'to the East' or 'to sunrise', it should always be checked if there is a connection between the orientation of a church and geometry of the Sun. In this paper, such examination is performed on the example of the church of St. John (the 13th century), one of four churches of the Studenica monastery, in the following way: 1) using gnomon method, the azimuth of the main longitudinal axis of the church is measured; 2) the altitude above the horizon of the point in which the extended axis of the church touches the true horizon is determined by cartometry; 3) the most probable dates when the Sun rises at that point are determined: May 7th according to Gregorian calendar, or April 30th according to Julian calendar, in the 13th century. The applied method is described in details and it can be applied for the analysis of the orientation of any other medieval church. This method can determine the time when the church was founded, as well as the fact if the church is original, or possibly erected on the foundations of some older sacral object
Network theory approach for data evaluation in the dynamic force spectroscopy of biomolecular interactions
Investigations of molecular bonds between single molecules and molecular
complexes by the dynamic force spectroscopy are subject to large fluctuations
at nanoscale and possible other aspecific binding, which mask the experimental
output. Big efforts are devoted to develop methods for effective selection of
the relevant experimental data, before taking the quantitative analysis of bond
parameters. Here we present a methodology which is based on the application of
graph theory. The force-distance curves corresponding to repeated pulling
events are mapped onto their correlation network (mathematical graph). On these
graphs the groups of similar curves appear as topological modules, which are
identified using the spectral analysis of graphs. We demonstrate the approach
by analyzing a large ensemble of the force-distance curves measured on:
ssDNA-ssDNA, peptide-RNA (system from HIV1), and peptide-Au surface. Within our
data sets the methodology systematically separates subgroups of curves which
are related to different intermolecular interactions and to spatial
arrangements in which the molecules are brought together and/or pulling speeds.
This demonstrates the sensitivity of the method to the spatial degrees of
freedom, suggesting potential applications in the case of large molecular
complexes and situations with multiple binding sites
RelativistiÄki model kvarkova
A general Lorentz-covariant quark model of mesons, whose nonrelativistic limit corresponds to Isgur-Scora-Grinstein-Wise model, is constructed. It possesses the heavy quark symmetry and can be easily applied to calculation of form factors. Besides it can be engaged in novel tasks, such a the investigation of the two photon decay of scalar mesons. Its behaviour in the infinite momentum frame and the light cone is discussed.Izveli smo poopÄeni Lorentz-kovarijantni model mezona Äiji nerelativistiÄki limes odgovara Isgur-Scora-Grinstein-Wiseovom modelu. Model ima teÅ”ko-kvarkovsku simetriju i može se primijeniti za raÄunanje faktora oblika. Osim toga u ovom se modelu mogu rjeÅ”avati nove zadaÄe kao Å”to je dvofotonski raspad skalarnih mezona. Raspravljamo svojstva modela u sustavu beskonaÄnog impulsa i na svjetlosnom stoÅ”cu
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