502,589 research outputs found
Congener Host Selection by the Pre-Dispersal Seed Predator, \u3ci\u3eApion Rostrum\u3c/i\u3e (Coleoptera: Apionidae)
Apion rostrum Say (Coleoptera: Apionidae) is the major seed predator of the wild indigo congeners, Baptisia alba and B. bracteata in the Russell Kirt Tallgrass Prairie, a reconstructed prairie located at College of DuPage, Illinois. This study, conducted during 2006, investigated factors attracting A. rostrum to each congener. The two Baptisia differ in developmental period, stature, and patterns of dispersion. B. bracteata flowers and initiates pods usually along a single raceme during late spring, and is a shorter plant that grows in clusters. In contrast, B. alba flowers and initiates pods beginning a month after B. bracteata, produces a tall central raceme with often several satellite racemes, and does not grow in dense clusters. Mating and ovipositing A. rostrum were observed on B. bracteata during the first half of June, and with greater abundance on B. alba from early June through mid July. Results of stepwise multiple regression showed a positive relationship of weevil counts per plant to raceme counts per cluster for B. bracteata and to inflated pod counts per plant for B. alba. The developmental synchrony between A. rostrum and pods of B. alba is evidence of a closer evolutionary relationship than the seed predator has with B. bracteata. This can explain the greater number of reproductive weevils seen on B. alba as well as the higher levels of pod infestations
Stationary state solutions for a gently stochastic nonlinear wave equation with ultraviolet cutoffs
We consider a non-linear, one-dimensional wave equation system with
finite-dimensional stochastic driving terms and with weak dissipation. A
stationary process that solves the system is used to model steady-state
non-equilibrium heat flow through a non-linear medium. We show existence and
uniqueness of invariant measures for the system modified with ultraviolet
cutoffs, and we obtain estimates for the field covariances with respect to
these measures, estimates that are uniform in the cutoffs. Finally, we discuss
the limit of these measures as the ultraviolet cutoffs are removed.Comment: 19 page
Robust Multi-Criteria Optimal Fuzzy Control of Continuous-Time Nonlinear Systems
This paper presents a novel fuzzy control design of continuous-time nonlinear systems with multiple performance criteria. The purpose behind this work is to improve the traditional fuzzy controller performance to satisfy several performance criteria simultaneously to secure quadratic optimality with inherent stability property together with dissipativity type of disturbance reduction. The Takagi– Sugeno fuzzy model is used in our control system design. By solving the linear matrix inequality at each time step, the control solution can be found to satisfy the mixed performance criteria. The effectiveness of the proposed technique is demonstrated by simulation of the control of the inverted pendulum system
Identification of 331 quantum Hall states with Mach-Zehnder interferometry
It has been shown recently that non-Abelian states and the spin-polarized and
unpolarized versions of the Abelian 331 state may have identical signatures in
Fabry-P\'{e}rot interferometry in the quantum Hall effect at filling factor
5/2. We calculate the Fano factor for the shot noise in a Mach-Zehnder
interferometer in the 331 states and demonstrate that it differs from the Fano
factor in the proposed non-Abelian states. The Fano factor depends periodically
on the magnetic flux through the interferometer. Its maximal value is  for the 331 states with a symmetry between two flavors of quasiparticles.
In the absence of such symmetry the Fano factor can reach . On
the other hand, for the Pfaffian and anti-Pfaffian states the maximal Fano
factor is . The period of the flux dependence of the Fano factor
is one flux quantum. If only quasiparticles of one flavor can tunnel through
the interferometer then the period drops to one half of the flux quantum. We
also discuss transport signatures of a general Halperin state with the filling
factor .Comment: 13 pages, 4 figures; Appendix on the states with the filling factor
  2+k/(k+2) adde
Analysis of the vertex with the light-cone QCD sum rules
In this article, we analyze the vertex  with the light-cone QCD
sum rules. The strong coupling constant  is an important
parameter in evaluating the charmonium absorption cross sections in searching
for the quark-gluon plasmas. Our numerical value for the  is
consistent with the prediction of the effective SU(4) symmetry and vector meson
dominance theory.Comment: 6 pages, 1 figure, revised versio
The geometric structure of nonholonomic mechanics
Many important problems in multibody dynamics, the dynamics of wheeled vehicles and motion generation, involve nonholonomic mechanics. Many of these systems have symmetry, such as the group of Euclidean motions in the plane or in space and this symmetry plays an important role in the theory. Despite considerable advances on both Hamiltonian and Lagrangian sides of the theory, there remains much to do. We report on progress on two of these fronts. The first is a Poisson description of the equations that is equivalent to those given by Lagrangian reduction, and second, a deeper understanding of holonomy for such systems. These results promise to lead to further progress on the stability issues and on locomotion generatio
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