7,137 research outputs found
Combinatorics and formal geometry of the master equation
We give a general treatment of the master equation in homotopy algebras and
describe the operads and formal differential geometric objects governing the
corresponding algebraic structures. We show that the notion of Maurer-Cartan
twisting is encoded in certain automorphisms of these universal objects
Model reconstructions for the Si(337) orientation
Although unstable, the Si(337) orientation has been known to appear in
diverse experimental situations such as the nanoscale faceting of Si(112), or
in the case of miscutting a Si(113) surface. Various models for Si(337) have
been proposed over time, which motivates a comprehensive study of the structure
of this orientation. Such a study is undertaken in this article, where we
report the results of a genetic algorithm optimization of the Si(337)- surface. The algorithm is coupled with a highly optimized empirical
potential for silicon, which is used as an efficient way to build a set of
possible Si(337) models; these structures are subsequently relaxed at the level
of ab initio density functional methods. Using this procedure, we retrieve most
of the (337) reconstructions proposed in previous works, as well as a number of
novel ones.Comment: 5 figures (low res.); to appear in J. Appl. Phy
Limits to clock synchronization induced by completely dephasing communication channels
Clock synchronization procedures are analyzed in the presence of imperfect
communications. In this context we show that there are physical limitations
which prevent one from synchronizing distant clocks when the intervening medium
is completely dephasing, as in the case of a rapidly varying dispersive medium.Comment: 6 Pages. Revised version as published in PR
Inspiration from Intersecting D-branes: General Supersymmetry Breaking Soft Terms in No-Scale -
Motivated by D-brane model building, we evaluate the - model
with additional vector-like particle multiplets, referred to as flippons,
within the framework of No-Scale Supergravity with non-vanishing general
supersymmetry breaking soft terms at the string scale. The viable phenomenology
is uncovered by applying all current experimental constraints, including but
not limited to the correct light Higgs boson mass, WMAP and Planck relic
density measurements, and several LHC constraints on supersymmetric particle
spectra. Four interesting regions of the parameter space arise, as well as
mixed scenarios, given by: (i) light stop coannihilation; (ii) pure Higgsino
dark matter; (iii) Higgs funnel; and (iv) light stau coannihilation. All
regions can generate the observed value of the relic density commensurate with
a 125 GeV light Higgs boson mass, with the exception of the relatively small
relic density value for the pure Higgsino lightest supersymmetric particle
(LSP). This work is concluded by gauging the model against present LHC search
constraints and derivation of the final states observable at the LHC for each
of these scenarios.Comment: 13 pages, 4 Figures, 4 Table
The Response of a Hot-Wire Anemometer to a Bubble of Air in Water
The sensitivity of peak voltage drop and duration of the change In sensor voltages due to the impaction of different size bubbles are confuted and measured. Excellent agreement between these is found for bubbles somewhat larger than the sensor diameter and smaller than Its effective length in water streams in a range of 1.5 to 9 feet per second. The method suggests a reliable method for sizing bubbles in a water stream. The effects due to nondirect hits are not treated
Process reconstruction from incomplete and/or inconsistent data
We analyze how an action of a qubit channel (map) can be estimated from the
measured data that are incomplete or even inconsistent. That is, we consider
situations when measurement statistics is insufficient to determine consistent
probability distributions. As a consequence either the estimation
(reconstruction) of the channel completely fails or it results in an unphysical
channel (i.e., the corresponding map is not completely positive). We present a
regularization procedure that allows us to derive physically reasonable
estimates (approximations) of quantum channels. We illustrate our procedure on
specific examples and we show that the procedure can be also used for a
derivation of optimal approximations of operations that are forbidden by the
laws of quantum mechanics (e.g., the universal NOT gate).Comment: 9pages, 5 figure
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