4,853 research outputs found
Evolving small-world networks with geographical attachment preference
We introduce a minimal extended evolving model for small-world networks which
is controlled by a parameter. In this model the network growth is determined by
the attachment of new nodes to already existing nodes that are geographically
close. We analyze several topological properties for our model both
analytically and by numerical simulations. The resulting network shows some
important characteristics of real-life networks such as the small-world effect
and a high clustering.Comment: 11 pages, 4 figure
High Dimensional Apollonian Networks
We propose a simple algorithm which produces high dimensional Apollonian
networks with both small-world and scale-free characteristics. We derive
analytical expressions for the degree distribution, the clustering coefficient
and the diameter of the networks, which are determined by their dimension
Vertex labeling and routing in expanded Apollonian networks
We present a family of networks, expanded deterministic Apollonian networks,
which are a generalization of the Apollonian networks and are simultaneously
scale-free, small-world, and highly clustered. We introduce a labeling of their
vertices that allows to determine a shortest path routing between any two
vertices of the network based only on the labels.Comment: 16 pages, 2 figure
Effects of the filter-feeding benthic bivalve corbicula fluminea on plankton community and water quality in aquatic ecosystems: A mesocosm study
The influence of filter-feeding bivalves on plankton communities, nutrients, and water quality in a given aquatic ecosystem is so profound that they can be considered ecosystem engineers. In a 70-day mesocosm experiment, we tested the hypothesis that Corbicula fluminea would change plankton community structure by reducing small zooplankton and large phytoplankton and improve water quality by reducing nutrients. We monitored levels of nitrogen and phosphorus, organic suspended solids (OSS), and light at the sediment surface. Within the plankton, phytoplankton biomass (as Chl a, >0.45 μm), the biomass of microphytoplankton (>20 μm), nanophytoplankton (2–20 μm), picophytoplankton (0.2–2 μm), and zooplankton were determined. Compared with the controls, C. fluminea reduced the abundance of rotifers and the biomass of phytoplankton, and picophytoplankton, thereby modifying the plankton community structure. We did not observe reductions in TN and TP concentration, but OSS concentrations were reduced, and light intensity at the sediment surface was increased as a result of the improved water transparency. Our research shows that colonization by C. fluminea may modify plankton community structure and improve water quality of eutrophic shallow lakes, shedding further light on the ecological roles of filter-feeding bivalves in aquatic ecosystems
Plasmapause surface wave oscillates the magnetosphere and diffuse aurora
Energy circulation in geospace lies at the heart of space weather research. In the inner
magnetosphere, the steep plasmapause boundary separates the cold dense plasmasphere,
which corotates with the planet, from the hot ring current/plasma sheet outside. Theoretical
studies suggested that plasmapause surface waves related to the sharp inhomogeneity exist
and act as a source of geomagnetic pulsations, but direct evidence of the waves and their role
in magnetospheric dynamics have not yet been detected. Here, we show direct observations
of a plasmapause surface wave and its impacts during a geomagnetic storm using multisatellite and ground-based measurements. The wave oscillates the plasmapause in the
afternoon-dusk sector, triggers sawtooth auroral displays, and drives outward-propagating
ultra-low frequency waves. We also show that the surface-wave-driven sawtooth auroras
occurred in more than 90% of geomagnetic storms during 2014–2018, indicating that they
are a systematic and crucial process in driving space energy dissipation
Non-Abelian Collective Excitations in Unlinearized Quark-Gluon Plasma Media
We study the effect of unlinearized medium on the collective excitations in
quark-gluon plasma. We present two kinds of non-Abelian oscillation solutions
which respectively correspond to weakly and strongly nonlinear coupling of
field components in color space. We also show that the weakly nonlinear
solution is similar to Abelian-like one but has the frequency shift, which is
of order , from eigenfrequency.Comment: 7 page
Measurement of the chi_{c2} Polarization in psi(2S) to gamma chi_{c2}
The polarization of the chi_{c2} produced in psi(2S) decays into gamma
chi_{c2} is measured using a sample of 14*10^6 psi(2S) events collected by
BESII at the BEPC. A fit to the chi_{c2} production and decay angular
distributions in psi(2S) to gamma chi_{c2}, chi_{c2} to pi pi and KK yields
values x=A_1/A_0=2.08+/-0.44 and y=A_2/A_0=3.03 +/-0.66, with a correlation
rho=0.92 between them, where A_{0,1,2} are the chi_{c2} helicity amplitudes.
The measurement agrees with a pure E1 transition, and M2 and E3 contributions
do not differ significantly from zero.Comment: 6 pages, 4 figures, 1 tabl
Measurement of the branching fractions of psi(2S) -> 3(pi+pi-) and J/psi -> 2(pi+pi-)
Using data samples collected at sqrt(s) = 3.686GeV and 3.650GeV by the BESII
detector at the BEPC, the branching fraction of psi(2S) -> 3(pi+pi-) is
measured to be [4.83 +- 0.38(stat) +- 0.69(syst)] x 10^-4, and the relative
branching fraction of J/psi -> 2(pi+pi-) to that of J/psi -> mu+mu- is measured
to be [5.86 +- 0.19(stat) +- 0.39(syst)]% via psi(2S) -> (pi+pi-)J/psi, J/psi
-> 2(pi+pi-). The electromagnetic form factor of 3(pi+pi-) is determined to be
0.21 +- 0.02 and 0.20 +- 0.01 at sqrt(s) = 3.686GeV and 3.650GeV, respectively.Comment: 17pages, 7 figures, submitted to Phys. Rev.
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