4,555 research outputs found
Sparse Graph Codes for Quantum Error-Correction
We present sparse graph codes appropriate for use in quantum
error-correction. Quantum error-correcting codes based on sparse graphs are of
interest for three reasons. First, the best codes currently known for classical
channels are based on sparse graphs. Second, sparse graph codes keep the number
of quantum interactions associated with the quantum error correction process
small: a constant number per quantum bit, independent of the blocklength.
Third, sparse graph codes often offer great flexibility with respect to
blocklength and rate. We believe some of the codes we present are unsurpassed
by previously published quantum error-correcting codes.Comment: Version 7.3e: 42 pages. Extended version, Feb 2004. A shortened
version was resubmitted to IEEE Transactions on Information Theory Jan 20,
200
Solution of a Braneworld Big Crunch/Big Bang Cosmology
We solve for the cosmological perturbations in a five-dimensional background
consisting of two separating or colliding boundary branes, as an expansion in
the collision speed V divided by the speed of light c. Our solution permits a
detailed check of the validity of four-dimensional effective theory in the
vicinity of the event corresponding to the big crunch/big bang singularity. We
show that the four-dimensional description fails at the first nontrivial order
in (V/c)^2. At this order, there is nontrivial mixing of the two relevant
four-dimensional perturbation modes (the growing and decaying modes) as the
boundary branes move from the narrowly-separated limit described by
Kaluza-Klein theory to the well-separated limit where gravity is confined to
the positive-tension brane. We comment on the cosmological significance of the
result and compute other quantities of interest in five-dimensional
cosmological scenarios.Comment: 54 pages, 12 figures, URL updated & 3 references adde
Conformal symmetry of brane world effective actions
A simple derivation of the low-energy effective action for brane worlds is
given, highlighting the role of conformal invariance. We show how to improve
the effective action for a positive- and negative-tension brane pair using the
AdS/CFT correspondence.Comment: 5 pages, published versio
On ordinal utility, cardinal utility, and random utility
Though the Random Utility Model (RUM) was conceived
entirely in terms of ordinal utility, the apparatus throughwhich it is widely practised exhibits properties of
cardinal utility. The adoption of cardinal utility as a
working operation of ordinal is perfectly valid, provided
interpretations drawn from that operation remain faithful
to ordinal utility. The paper considers whether the latterrequirement holds true for several measurements commonly
derived from RUM. In particular it is found that
measurements of consumer surplus change may depart from
ordinal utility, and exploit the cardinality inherent in
the practical apparatus.
Baseline performance and emissions data for a single-cylinder, direct-injected diesel engine
Comprehensive fuel consumption, mean effective cylinder pressure, and emission test results for a supercharged, single-cylinder, direct-injected, four-stroke-cycle, diesel test engine are documented. Inlet air-to-exhaust pressure ratios were varied from 1.25 to 3.35 in order to establish the potential effects of turbocharging techniques on engine performance. Inlet air temperatures and pressures were adjusted from 34 to 107 C and from 193 to 414 kPa to determine the effects on engine performance and emissions. Engine output ranged from 300 to 2100 kPa (brake mean effective pressure) in the speed range of 1000 to 3000 rpm. Gaseous and particulate emission rates were measured. Real-time values of engine friction and pumping loop losses were measured independently and compared with motored engine values
Effect of Dormant ‘MidIron’ Bermudagrass Colorant Applications on Clothing Blemishing
Minimal research exists on potential clothing blemishing when athletes contact turfgrass applied with colorants. Field trials were initiated February 16, 2017, and conducted to test the effect of turfgrass colorant applications on clothing blemishing if an athlete is to come in contact with the playing surface. Turfgrass colorants will adhere to turfgrass leaf blades and do not blemish clothing. However, tested turfgrass pigments did result in significant blemishing of clothing
Remote sensing of Pacific hurricane and radiometric measurements from foam and slicks
There are no author-identified significant results in this report
Holographic predictions for cosmological 3-point functions
We present the holographic predictions for cosmological 3-point correlators,
involving both scalar and tensor modes, for a universe which started in a
non-geometric holographic phase. Holographic formulae relate the cosmological
3-point functions to stress tensor correlation functions of a holographically
dual three-dimensional non-gravitational QFT. We compute these correlators at
1-loop order for a theory containing massless scalars, fermions and gauge
fields, and present an extensive analysis of the constraints due to Ward
identities showing that they uniquely determine the correlators up to a few
constants. We define shapes for all cosmological bispectra and compare the
holographic shapes to the slow-roll ones, finding that some are distinguishable
while others, perhaps surprisingly, are not.Comment: 51pp; 4 fig
The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN Spacecraft
We analyzed 44 passes of the MAVEN spacecraft through the magnetosphere,
arranged by the angle between electric field vector and the projection of
spacecraft position radius vector in the YZ plane in MSE coordinate system
( E ). All passes were divided into 3 angular sectors near 0{\deg},
90{\deg} and 180{\deg} E angles in order to estimate the role of IMF
direction in plasma and magnetic properties of dayside Martian magnetosphere.
The time interval chosen was from January 17 through February 4, 2016 when
MAVEN was crossing the dayside magnetosphere at SZA ~ 70{\deg}. Magnetosphere
as the region with prevailing energetic planetary ions is always found between
the magnetosheath and the ionosphere. 3 angular sectors of dayside interaction
region in MSE coordinate system with different orientation of the solar wind
electric field vector E = -1/c V x B showed that for each sector one can find
specific profiles of the magnetosheath, the magnetic barrier and the
magnetosphere. Plume ions originate in the northern MSE sector where motion
electric field is directed from the planet. This electric field ejects
magnetospheric ions leading to dilution of magnetospheric heavy ions
population, and this effect is seen in some magnetospheric profiles. Magnetic
barrier forms in front of the magnetosphere, and relative magnetic field
magnitudes in these two domains vary. The average height of the boundary with
ionosphere is ~530 km and the average height of the magnetopause is ~730 km. We
discuss the implications of the observed magnetosphere structure to the
planetary ions loss mechanism.Comment: 24 pages, 13 figure
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