4,710 research outputs found
INCOMPOSITA: a MADS-box gene controlling prophyll development and floral meristem identity in Antirrhinum
Plankton ecology: The past two decades of progress
This is a selected account of recent developments
in plankton ecology. The examples have been
chosen for their degree of innovation during the
past two decades and for their general ecological
importance. They range from plankton autecology
over interactions between populations to community
ecology. The autecology of plankton is
represented by the hydromechanics of plankton
(the problem of life in a viscous environment) and
by the nutritional ecology of phyto- and zooplankton.
Population level studies are represented
by competition, herbivory (grazing), and zooplankton
responses to predation. Community
ecology is represented by the debate about bottom-
up vs. top-down control of community organization,
by the PEG model of seasonal plankton
succession, and by the recent discovery of the microbial
food web
Système intégré de gestion des stockages et d'alerte de crues dans les bassins versants urbains et les petits bassins versants
Topological superfluid of spinless Fermi gases in p-band honeycomb optical lattices with on-site rotation
In this paper, we put forward to another route realizing topological
superfluid (TS). In contrast to conventional method, spin-orbit coupling and
external magnetic field are not requisite. Introducing an experimentally
feasible technique called on-site rotation (OSR) into p-band honeycomb optical
lattices for spinless Fermi gases and considering CDW and pairing on the same
footing, we investigate the effects of OSR on superfluidity. The results
suggest that when OSR is beyond a critical value, where CDW vanishes, the
system transits from a normal superfluid (NS) with zero TKNN number to TS
labeled by a non-zero TKNN number. In addition, phase transitions between
different TS are also possible
Molecular and genetic interactions between STYLOSA and GRAMINIFOLIA in the control of Antirrhinum vegetative and reproductive development
Heavy quark action on the anisotropic lattice
We investigate the improved quark action on anisotropic lattice as a
potential framework for the heavy quark, which may enable precision computation
of hadronic matrix elements of heavy-light mesons. The relativity relations of
heavy-light mesons as well as of heavy quarkonium are examined on a quenched
lattice with spatial lattice cutoff 1.6 GeV and the
anisotropy . We find that the bare anisotropy parameter tuned for the
massless quark describes both the heavy-heavy and heavy-light mesons within 2%
accuracy for the quark mass , which covers the charm quark
mass. This bare anisotropy parameter also successfully describes the
heavy-light mesons in the quark mass region within the
same accuracy. Beyond this region, the discretization effects seem to grow
gradually. The anisotropic lattice is expected to extend by a factor the
quark mass region in which the parameters in the action tuned for the massless
limit are applicable for heavy-light systems with well controlled systematic
errors.Comment: 11 pages, REVTeX4, 11 eps figure
Entropic Tightening of Vibrated Chains
We investigate experimentally the distribution of configurations of a ring
with an elementary topological constraint, a ``figure-8'' twist. Using vibrated
granular chains, which permit controlled preparation and direct observation of
such a constraint, we show that configurations where one of the loops is tight
and the second is large are strongly preferred. This agrees with recent
predictions for equilibrium properties of topologically-constrained polymers.
However, the dynamics of the tightening process weakly violate detailed
balance, a signature of the nonequilibrium nature of this system.Comment: 4 pages, 4 figure
Nitrate- and silicate-competition among antarctic phytoplankton
Natural phytoplankton from antarctic waters in the Drake Passage were used for competition experiments in semicontinuous cultures. The outcome of interspecific competition for silicate and nitrate was studied at a range of Si:N ratios (from 2.6:1 to 425:1) and at three different dilution rates. For five species Monod kinetics of silicate-and nitrate-limited growth has been established. Comparison between theoretical predictions derived from Monod kinetics and the outcome of competition experiments showed only minor deviations. Contrary to literature data, considerable depletion of nitrate was found in antarctic seawater. Both the concentrations of soluble silicate and of nitrate were too low to support maximum growth rates of some of the diatom species under investigation
Influence of long-range correlated surface and near the surface disorder on the process of adsorption of long-flexible polymer chains
The influence of long-range correlated surface and decaying near surface
disorder with quenched defects is studied. We consider a correlation function
for the defects of the form , where and
being the coordinate in the direction perpendicular to the surface and
denotes the distance parallel to the surface. We investigate the process of
adsorption of long-flexible polymer chains with excluded volume interactions on
a "marginal" and attractive wall in the framework of renormalization group
field theoretical approach up to first order of perturbation theory in a double
(,)- expansion (, ) for the
semi-infinite model with the above mentioned type of
surface and near the surface disorder in the limit . In particular we
study two limiting cases. First, we investigate the scenario where the chain's
extension it much larger then . Second, we consider the case where the
chain's extension is of the order of . For both cases we obtained series
for bulk and the whole set of surface critical exponents, characterizing the
process of adsorption of long-flexible polymer chains at the surface. The
polymer linear dimensions parallel and perpendicular to the surface and the
corresponding partition functions as well as the behavior of monomer density
profiles and the fraction of adsorbed monomers at the surface and in the volume
are studied.Comment: 31 pages, 5 figures, 2 table
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