11,840 research outputs found
The Coupling of Shape Dynamics to Matter
Shape Dynamics (SD) is a theory dynamically equivalent to vacuum General
Relativity (GR), which has a different set of symmetries. It trades refoliation
invariance, present in GR, for local 3-dimensional conformal invariance. This
contribution to the Loops 11 conference addresses one of the more urgent
questions regarding the equivalence: is it possible to incorporate normal
matter in the new framework? The answer is yes, in certain regimes. We present
general criteria for coupling and apply it to a few examples.The outcome
presents bounds and conditions on scalar densities (such as the Higgs potential
and the cosmological constant) not present in GR.Comment: 4 pages. Contribution to Loops '11 conference in Madrid, to appear in
Journal of Physics: Conference Series (JPCS
Enhanced graphene nonlinear response through geometrical plasmon focusing
We propose a simple approach to couple light into graphene plasmons and focus these excitations at
focal spots of a size determined by the plasmon wavelength, thus producing high optical field
enhancement that boosts the nonlinear response of the material. More precisely, we consider a
graphene structure in which incident light is coupled to its plasmons at the carbon edges and
subsequently focused on a spot of size comparable to the plasmon wavelength. We observe large
confinement of graphene plasmons, materializing in small, intense focal spots, in which the
extraordinary nonlinear response of this material leads to relatively intense harmonic generation.
This result shows the potential of plasmon focusing in suitably edged graphene structures to produce
large field confinement and nonlinear response without involving elaborated nanostructuring.Peer ReviewedPostprint (published version
On the classification and properties of noncommutative duplicates
We give an explicit description of the set of all factorization structures,
or twisting maps, existing between the algebras k^2 and k^2, and classify the
resulting algebras up to isomorphism. In the process we relate several
different approaches formerly taken to deal with this problem, filling a gap
that appeared in a recent paper by Cibils. We also provide a counterexample to
a result concerning the Hochschild (co)homology appeared in a paper by J.A.
Guccione and J.J. Guccione.Comment: 11 pages, no figure
Measuring the Dynamics of Young and Small Businesses: Integrating the Employer and Nonemployer Universes
We develop a preliminary version of an Integrated Longitudinal Business Database (ILBD) that combines administrative records and survey data for all employer and nonemployer business units in the United States. Unlike other large-scale business databases, the ILBD tracks business transitions from nonemployer to employer status. This feature of the ILBD opens a new frontier for the study of business formation, early lifecycle dynamics and the precursors to job creation in the U.S. economy. There are 5.4 million nonfarm business firms with employees as of 2000 and another 15.5 million with no employees. Our analysis focuses on 40 industries that account for nearly half of nonemployers and 36 percent of nonemployer revenues. Within these industries, nonemployers account for 14 percent of business revenues. About 220,000 of the seven million nonemployers in our selected industries hire workers and migrate to the employer universe over a three-year horizon. These Migrants account for 20 percent of revenue among young employers (three years or less since first hire). Compared to other nonemployers, the revenue of Migrants grows very rapidly in the year prior to and the year of transition to employer status.
Sexual Maturity and Spawning of the Greenland Halibut (Reinhardtius hippoglossoides) From Flemish Pass Area
10 páginas, 4 figuras, 3 tablas.-- Scientific Council MeetingPeer reviewe
Diffusion in a Granular Fluid - Simulation
The linear response description for impurity diffusion in a granular fluid
undergoing homogeneous cooling is developed in the preceeding paper. The
formally exact Einstein and Green-Kubo expressions for the self-diffusion
coefficient are evaluated there from an approximation to the velocity
autocorrelation function. These results are compared here to those from
molecular dynamics simulations over a wide range of density and inelasticity,
for the particular case of self-diffusion. It is found that the approximate
theory is in good agreement with simulation data up to moderate densities and
degrees of inelasticity. At higher density, the effects of inelasticity are
stronger, leading to a significant enhancement of the diffusion coefficient
over its value for elastic collisions. Possible explanations associated with an
unstable long wavelength shear mode are explored, including the effects of
strong fluctuations and mode coupling
Analytical solution of a one-dimensional Ising model with zero temperature dynamics
The one-dimensional Ising model with nearest neighbour interactions and the
zero-temperature dynamics recently considered by Lefevre and Dean -J. Phys. A:
Math. Gen. {\bf 34}, L213 (2001)- is investigated. By introducing a
particle-hole description, in which the holes are associated to the domain
walls of the Ising model, an analytical solution is obtained. The result for
the asymptotic energy agrees with that found in the mean field approximation.Comment: 6 pages, no figures; accepted in J. Phys. A: Math. Gen. (Letter to
the Editor
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