7,773 research outputs found
Orbital approach to microstate free entropy
Motivated by Voiculescu's liberation theory, we introduce the orbital free
entropy for non-commutative self-adjoint random variables (also for
"hyperfinite random multi-variables"). Besides its basic properties the
relation of with the usual free entropy is shown. Moreover,
the dimension counterpart of is discussed, and we
obtain the relation of with the original free entropy
dimension with applications to itself.Comment: 38 pages; Section 5 was largely improved and Section 6 was adde
Mechanically-Induced Transport Switching Effect in Graphene-based Nanojunctions
We report a theoretical study suggesting a novel type of electronic switching
effect, driven by the geometrical reconstruction of nanoscale graphene-based
junctions. We considered junction struc- tures which have alternative
metastable configurations transformed by rotations of local carbon dimers. The
use of external mechanical strain allows a control of the energy barrier
heights of the potential profiles and also changes the reaction character from
endothermic to exothermic or vice-versa. The reshaping of the atomic details of
the junction encode binary electronic ON or OFF states, with ON/OFF
transmission ratio that can reach up to 10^4-10^5. Our results suggest the
possibility to design modern logical switching devices or mechanophore sensors,
monitored by mechanical strain and structural rearrangements.Comment: 10 pages, 4 figure
A Simple Model for Estimating Water Balance and Salinity of Reservoirs and Outflow
Reservoir storage reduces fluctuation in streamflow salinity, yet increases outflow salinity
because of water evaporation. These processes are highly relevant to developing water
management strategy, yet the method to predict outflow salinity has not been adequately
examined. The study reported here examined the water and salt balance in a reservoir using a
two-layer model. This model assumes that inflow blends with the storage, but the water
evaporation takes place from the surface layer, and the percolation losses from the subsurface.
The thickness of the first layer where salinity increases with evaporation was estimated through
calibration against the measured outflow salinity. The changes in salinity were computed using a
moving average method on a monthly time step. This model was applied first to Red Bluff
Reservoir of the Middle Pecos River, then to Elephant Butte, Amistad, and Falcon along the Rio
Grande. The outflow salinity projected by the model was in good agreement with the measured,
except under a few circumstances where mixing of inflow and reservoir storage was suspected to
be incomplete. The accuracy of prediction can be improved by improving the estimate of initial
salinity of reservoir storage, which is currently taken as being equal to outflow salinity at the onset
of the simulation
Free initial wave packets and the long-time behavior of the survival and nonescape probabilities
The behavior of both the survival S(t) and nonescape P(t) probabilities at
long times for the one-dimensional free particle system is shown to be closely
connected to that of the initial wave packet at small momentum. We prove that
both S(t) and P(t) asymptotically exhibit the same power-law decrease at long
times, when the initial wave packet in momentum representation behaves as O(1)
or O(k) at small momentum. On the other hand, if the integer m becomes greater
than 1, S(t) and P(t) decrease in different power-laws at long times.Comment: 4 pages, 3 figures, Title and organization changed, however the
results not changed, To appear in Phys. Rev.
Eficiência agronômica de rochas fontes de potássio para cultura da soja na região do arenito, Estado do Paraná.
Nonmeromorphic operator product expansion and C_2-cofiniteness for a family of W-algebras
We prove the existence and associativity of the nonmeromorphic operator
product expansion for an infinite family of vertex operator algebras, the
triplet W-algebras, using results from P(z)-tensor product theory. While doing
this, we also show that all these vertex operator algebras are C_2-cofinite.Comment: 21 pages, to appear in J. Phys. A: Math. Gen.; the exposition is
improved and one reference is adde
Darwin Tames an Andromeda Dwarf: Unraveling the Orbit of NGC 205 Using a Genetic Algorithm
NGC 205, a close satellite of the M31 galaxy, is our nearest example of a
dwarf elliptical galaxy. Photometric and kinematic observations suggest that
NGC 205 is undergoing tidal distortion from its interaction with M31. Despite
earlier attempts, the orbit and progenitor properties of NGC 205 are not well
known. We perform an optimized search for these unknowns by combining a genetic
algorithm with restricted N-body simulations of the interaction. This approach,
coupled with photometric and kinematic observations as constraints, allows for
an effective exploration of the parameter space. We represent NGC 205 as a
static Hernquist potential with embedded massless test particles that serve as
tracers of surface brightness. We explore 3 distinct, initially stable
configurations of test particles: cold rotating disk, warm rotating disk, and
hot, pressure-supported spheroid. Each model reproduces some, but not all, of
the observed features of NGC 205, leading us to speculate that a rotating
progenitor with substantial pressure support could match all of the
observables. Furthermore, plausible combinations of mass and scale length for
the pressure-supported spheroid progenitor model reproduce the observed
velocity dispersion profile. For all 3 models, orbits that best match the
observables place the satellite 11+/-9 kpc behind M31 moving at very large
velocities: 300-500 km/s on primarily radial orbits. Given that the observed
radial component is only 54 km/s, this implies a large tangential motion for
NGC 205, moving from the NW to the SE. These results suggest NGC 205 is not
associated with the stellar arc observed to the NE of NGC 205. Furthermore, NGC
205's velocity appears to be near or greater than its escape velocity,
signifying that the satellite is likely on its first M31 passage.Comment: 34 pages, 20 figures, accepted for publication in the Astrophysical
Journal, A pdf version with high-resolution figures may be obtained from
http://www.ucolick.org/~kirsten/ms.pd
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