1,326 research outputs found
Nica-Toeplitz algebras associated with product systems over right LCM semigroups
We prove uniqueness of representations of Nica-Toeplitz algebras associated
to product systems of -correspondences over right LCM semigroups by
applying our previous abstract uniqueness results developed for
-precategories. Our results provide an interpretation of conditions
identified in work of Fowler and Fowler-Raeburn, and apply also to their
crossed product twisted by a product system, in the new context of right LCM
semigroups, as well as to a new, Doplicher-Roberts type -algebra
associated to the Nica-Toeplitz algebra. As a derived construction we develop
Nica-Toeplitz crossed products by actions with completely positive maps. This
provides a unified framework for Nica-Toeplitz semigroup crossed products by
endomorphisms and by transfer operators. We illustrate these two classes of
examples with semigroup -algebras of right and left semidirect products.Comment: Title changed from "Nica-Toeplitz algebras associated with right
tensor C*-precategories over right LCM semigroups: part II examples". The
manuscript accepted in J. Math. Anal. App
The benefits of combining seasonal anomalies and technical trading rules
Although many seasonal anomalies and technical trading rules have been shown to have predictive ability, investigations have focused only on them operating individually. We study the benefits of trading based on combinations of three of the best known effects: the moving average rule, the turn of the month effect, and the Halloween effect. We show that the rules can be combined effectively, giving significant levels of returns predictability with low risk and offering the possibility of profitable trading. This new investment approach is especially beneficial for a typical individual investor, who faces high transaction costs and is poorly diversified
A mathematical model for mechanically-induced deterioration of the binder in lithium-ion electrodes
This study is concerned with modeling detrimental deformations of the binder
phase within lithium-ion batteries that occur during cell assembly and usage. A
two-dimensional poroviscoelastic model for the mechanical behavior of porous
electrodes is formulated and posed on a geometry corresponding to a thin
rectangular electrode, with a regular square array of microscopic circular
electrode particles, stuck to a rigid base formed by the current collector.
Deformation is forced both by (i) electrolyte absorption driven binder
swelling, and; (ii) cyclic growth and shrinkage of electrode particles as the
battery is charged and discharged. The governing equations are upscaled in
order to obtain macroscopic effective-medium equations. A solution to these
equations is obtained, in the asymptotic limit that the height of the
rectangular electrode is much smaller than its width, that shows the
macroscopic deformation is one-dimensional. The confinement of macroscopic
deformations to one dimension is used to obtain boundary conditions on the
microscopic problem for the deformations in a 'unit cell' centered on a single
electrode particle. The resulting microscale problem is solved using numerical
(finite element) techniques. The two different forcing mechanisms are found to
cause distinctly different patterns of deformation within the microstructure.
Swelling of the binder induces stresses that tend to lead to binder
delamination from the electrode particle surfaces in a direction parallel to
the current collector, whilst cycling causes stresses that tend to lead to
delamination orthogonal to that caused by swelling. The differences between the
cycling-induced damage in both: (i) anodes and cathodes, and; (ii) fast and
slow cycling are discussed. Finally, the model predictions are compared to
microscopy images of nickel manganese cobalt oxide cathodes and a qualitative
agreement is found.Comment: 25 pages, 11 figure
Color octet scalars and high pT four-jet events at LHC
We study the effect of color octet scalars on the high transverse momenta
four-jet cross section at the LHC. We consider both weak singlet and doublet
scalars, concentrating on the case of small couplings to quarks. We find that a
relatively early discovery at the LHC is possible for a range of scalar masses.Comment: 5 pages, 9 figure
Capacities of Quantum Channels for Massive Bosons and Fermions
We consider the capacity of classical information transfer for noiseless
quantum channels carrying a finite average number of massive bosons and
fermions. The maximum capacity is attained by transferring the Fock states
generated from the grand-canonical ensemble. Interestingly, the channel
capacity for a Bose gas indicates the onset of a Bose-Einstein condensation, by
changing its qualitative behavior at the criticality, while for a channel
carrying weakly attractive fermions, it exhibits the signatures of
Bardeen-Cooper-Schrieffer transition. We also show that for noninteracting
particles, fermions are better carriers of information than bosons.Comment: 4 pages, 3 eps figures, RevTeX4; v2: discussions added, small
changes, published versio
Saturation of front propagation in a reaction-diffusion process describing plasma damage in porous low-k materials
We propose a three-component reaction-diffusion system yielding an asymptotic
logarithmic time-dependence for a moving interface. This is naturally related
to a Stefan-problem for which both one-sided Dirichlet-type and von
Neumann-type boundary conditions are considered. We integrate the dependence of
the interface motion on diffusion and reaction parameters and we observe a
change from transport behavior and interface motion \sim t^1/2 to logarithmic
behavior \sim ln t as a function of time. We apply our theoretical findings to
the propagation of carbon depletion in porous dielectrics exposed to a low
temperature plasma. This diffusion saturation is reached after about 1 minute
in typical experimental situations of plasma damage in microelectronic
fabrication. We predict the general dependencies on porosity and reaction
rates.Comment: Accepted for publication in Phys. Rev.
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