8,084 research outputs found
Linking Shade Coffee Certification To Biodiversity Conservation: Butterflies And Birds In Chiapas, Mexico
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117232/1/eap2004143642.pd
An Index Of Management Intensity For Coffee Agroecosystems To Evaluate Butterfly Species Richness
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117238/1/eap20031351491.pd
Pulse propagation in decorated granular chains: An analytical approach
We study pulse propagation in one-dimensional chains of spherical granules
decorated with small grains placed between large granules. The effect of the
small granules can be captured by replacing the decorated chains by undecorated
chains of large granules of appropriately renormalized mass and effective
interaction between the large granules. This allows us to obtain simple
analytic expressions for the pulse propagation properties using a
generalization of the binary collision approximation introduced in our earlier
work [Phys. Rev. E in print (2009); Phys. Rev. E {\bf 69}, 037601 (2004)]Comment: 10 pages and 12 figure
Observation of two-wave structure in strongly nonlinear dissipative granular chains
In a strongly nonlinear viscous granular chain under conditions of loading
that exclude stationary waves (e.g., impact by a single grain) we observe a
pulse that consists of two interconnected but distinct parts. One is a leading
narrow "primary pulse" with properties similar to a solitary wave in a "sonic
vacuum." It arises from strong nonlinearity and discreteness in the absence of
dissipation, but now decays due to viscosity. The other is a broad, much more
persistent shock-like "secondary pulse" trailing the primary pulse and caused
by viscous dissipation. The medium behind the primary pulse is transformed from
a "sonic vacuum" to a medium with finite sound speed. When the rapidly decaying
primary pulse dies, the secondary pulse continues to propagate in the "sonic
vacuum," with an oscillatory front if the viscosity is relatively small, until
its eventual (but very slow) disintegration. Beyond a critical viscosity there
is no separation of the two pulses, and the dissipation and nonlinearity
dominate the shock-like attenuating pulse which now exhibits a nonoscillatory
front
Magnetic field-induced insulating behavior in highly oriented pyrolitic graphite
We propose an explanation for the apparent semimetal-insulator transition
observed in highly oriented pyrolitic graphite in the presence of magnetic
field perpendicular to the layers. We show that the magnetic field opens an
excitonic gap in the linear spectrum of the Coulomb interacting quasiparticles,
in a close analogy with the phenomenon of dynamical chiral symmetry breaking in
the relativistic theories of the 2+1-dimensional Dirac fermions. Our
strong-coupling appoach allows for a non-perturbative description of the
corresponding critical behavior
NMR C-NOT gate through Aharanov-Anandan's phase shift
Recently, it is proposed to do quantum computation through the Berry's
phase(adiabatic cyclic geometric phase) shift with NMR (Jones et al, Nature,
403, 869(2000)). This geometric quantum gate is hopefully to be fault tolerant
to certain types of errors because of the geometric property of the Berry
phase. Here we give a scheme to realize the NMR C-NOT gate through
Aharonov-Anandan's phase(non-adiabatic cyclic phase) shift on the dynamic phase
free evolution loop.
In our scheme, the gate is run non-adiabatically, thus it is less affected by
the decoherence. And, in the scheme we have chosen the the zero dynamic phase
time evolution loop in obtaining the gepmetric phase shift, we need not take
any extra operation to cancel the dynamic phase.Comment: 5 pages, 1 figur
Spatially extended emission around the Cepheid RS Puppis in near-infrared hydrogen lines. Adaptive optics imaging with VLT/NACO
It has been recently discovered that Cepheids harbor circumstellar envelopes
(CSEs). RS Pup is the Cepheid that presents the most prominent circumstellar
envelope known, the origin of which is not yet understood. Our purpose is to
estimate the flux contribution of the CSE around RS Pup at the one arcsecond
scale (~2000 AU) and to investigate its geometry, especially regarding
asymmetries, to constrain its physical properties. We obtained near-infrared
images in two narrow band filters centered on \lambda = 1.644 and 2.180 \mu m
(NB 1.64 and IB 2.18, respectively) that comprise two recombination lines of
hydrogen: the 12-4 and 7-4 (Brackett \gamma) transitions, respectively. We used
NACO's cube mode observations in order to improve the angular resolution with
the shift-and-add technique, and to qualitatively study the symmetry of the
spatially extended emission from the CSE with a statistical study of the
speckle noise. We probably detect at a 2\sigma level an extended emission with
a relative flux (compared with the star in the same filter) of 38 17% in
the NB 1.64 filter and 24 11% in the IB 2.18 filter. This emission is
centered on RS Pup and does not present any detectable asymmetry. We attribute
the detected emission to the likely presence of an hydrogen envelope
surrounding the star
Parallel
In this paper we present Parallel, a videogame with a powerful story of mystery, suspense and puzzle-solving. Parallel provides an interactive storyline where the actions players take throughout the game will define the course of the story and alter events. The environment created in the game is unique and it was improved from testing with several subjects on a prototype of the tutorial. Parallel’s main potential is the sense of immersion it can provide with its obscure environment, dynamic dialogs using an artificial intelligent agent and its interactive storyline.info:eu-repo/semantics/acceptedVersio
Cooling process for inelastic Boltzmann equations for hard spheres, Part II: Self-similar solutions and tail behavior
We consider the spatially homogeneous Boltzmann equation for inelastic hard
spheres, in the framework of so-called constant normal restitution
coefficients. We prove the existence of self-similar solutions, and we give
pointwise estimates on their tail. We also give general estimates on the tail
and the regularity of generic solutions. In particular we prove Haff 's law on
the rate of decay of temperature, as well as the algebraic decay of
singularities. The proofs are based on the regularity study of a rescaled
problem, with the help of the regularity properties of the gain part of the
Boltzmann collision integral, well-known in the elastic case, and which are
extended here in the context of granular gases.Comment: 41 page
- …