125,437 research outputs found
Possible Suppression of Resonant Signals for Split-UED by Mixing at the LHC?
The mixing of the imaginary parts of the transition amplitudes of nearby
resonances via the breakdown of the Breit-Wigner approximation has been shown
to lead to potentially large modifications in the signal rates for new physics
at colliders. In the case of suppression, this effect may be significant enough
to lead to some new physics signatures being initially missed in searches at,
e.g., the LHC. Here we explore the influence of this `width mixing' on the
production of the nearly degenerate, level-2 Kaluza-Klein (KK) neutral gauge
bosons present in Split-UED. We demonstrate that in this particular case large
cross section modifications in the resonance region are necessarily absent and
explain why this is so based on the group theoretical structure of the SM.Comment: 10 pages, 2 figures; discussion and references adde
Gluon polarization in the proton
We combine heavy-quark renormalization group arguments with our understanding
of the nucleon's wavefunction to deduce a bound on the gluon polarization Delta
g in the proton. The bound is consistent with the values extracted from spin
experiments at COMPASS and RHIC.Comment: 4 page
Nondestructive testing techniques used in analysis of honeycomb structure bond strength
DOT /Driver-Displacement Oriented Transducer/, applicable to both lap shear type application and honeycomb sandwich structures, measures the displacement of the honeycomb composite face sheet. It incorporates an electromagnetic driver and a displacement measuring system into a single unit to provide noncontact bond strength measurements
EXAFS study of nickel tetracarbonyl and nickel clusters in zeolite Y
Adsorption and thermal decomposition of Ni(CO)4 in the cage system of zeolite Y
have been studied with EXAFS, electron microscopy and IR spectroscopy , Ni(CO)4
is adsorbed as an intact molecule in both cation - free zeolite Y and NaY. Symmetry
changes of the molecule in NaY are assigned to the formation of Na—OC-IMi bridges.
Thermal treatment of the Ni(CO)4/NaY adduct leads to loss of CO concomitant with
the formation of a binodal Ni phase. A major part of the forms clusters with
diameter between 0.5 and about 1.5 nm, in addition to larger crystallites
(5-30 nm), sticking at the outer surface of the zeolite matrix.,
The Ni-Ni scattering amplitude indicates increasing average particle size with
increasing temperature
Analytical Modeling of Uplink Cellular Networks
Cellular uplink analysis has typically been undertaken by either a simple
approach that lumps all interference into a single deterministic or random
parameter in a Wyner-type model, or via complex system level simulations that
often do not provide insight into why various trends are observed. This paper
proposes a novel middle way using point processes that is both accurate and
also results in easy-to-evaluate integral expressions based on the Laplace
transform of the interference. We assume mobiles and base stations are randomly
placed in the network with each mobile pairing up to its closest base station.
Compared to related recent work on downlink analysis, the proposed uplink model
differs in two key features. First, dependence is considered between user and
base station point processes to make sure each base station serves a single
mobile in the given resource block. Second, per-mobile power control is
included, which further couples the transmission of mobiles due to
location-dependent channel inversion. Nevertheless, we succeed in deriving the
coverage (equivalently outage) probability of a typical link in the network.
This model can be used to address a wide variety of system design questions in
the future. In this paper we focus on the implications for power control and
see that partial channel inversion should be used at low
signal-to-interference-plus-noise ratio (SINR), while full power transmission
is optimal at higher SINR.Comment: to appear, IEEE Transactions on Wireless Communication
Peeled film GaAs solar cells for space power
Gallium arsenide (GaAs) peeled film solar cells were fabricated, by Organo-Metallic Vapor Phase Epitaxy (OMVPE), incorporating an aluminum arsenide (AlAs) parting layer between the device structure and the GaAs substrate. This layer was selectively removed by etching in dilute hydrofloric (HF) acid to release the epitaxial film. Test devices exhibit high series resistance due to insufficient back contact area. A new design is presented which uses a coverglass superstrate for structural support and incorporates a coplanar back contact design. Devices based on this design should have a specific power approaching 700 W/Kg
Numerical calculations of a high brilliance synchrotron source and on issues with characterizing strong radiation damping effects in non-linear Thomson/Compton backscattering experiments
A number of theoretical calculations have studied the effect of radiation
reaction forces on radiation distributions in strong field counter-propagating
electron beam-laser interactions, but could these effects - including quantum
corrections - be observed in interactions with realistic bunches and focusing
fields, as is hoped in a number of soon to be proposed experiments? We present
numerical calculations of the angularly resolved radiation spectrum from an
electron bunch with parameters similar to those produced in laser wakefield
acceleration experiments, interacting with an intense, ultrashort laser pulse.
For our parameters, the effects of radiation damping on the angular
distribution and energy distribution of \emph{photons} is not easily
discernible for a "realistic" moderate emittance electron beam. However,
experiments using such a counter-propagating beam-laser geometry should be able
to measure such effects using current laser systems through measurement of the
\emph{electron beam} properties. In addition, the brilliance of this source is
very high, with peak spectral brilliance exceeding
photonssmmmrad% bandwidth with
approximately 2% efficiency and with a peak energy of 10 MeV.Comment: 11 figures, 11 page
Application of ERTS-1 data to integrated state planning in the state of Maryland
There are no author-identified significant results in this report
The principle of equivalence and projective structure in space-times
This paper discusses the extent to which one can determine the space-time
metric from a knowledge of a certain subset of the (unparametrised) geodesics
of its Levi-Civita connection, that is, from the experimental evidence of the
equivalence principle. It is shown that, if the space-time concerned is known
to be vacuum, then the Levi-Civita connection is uniquely determined and its
associated metric is uniquely determined up to a choice of units of
measurement, by the specification of these geodesics. It is further
demonstrated that if two space-times share the same unparametrised geodesics
and only one is assumed vacuum then their Levi-Civita connections are again
equal (and so the other metric is also a vacuum metric) and the first result
above is recovered.Comment: 23 pages, submitted to Classical and Quantum Gravit
Using presence-absence data to establish reserve selection procedures that are robust to temporal species turnover
Previous studies suggest that a network of nature reserves with maximum efficiency (obtained by selecting the minimum area such that each species is represented once) is likely to be insufficient to maintain species in the network over time. Here, we test the performance of three selection strategies which require presence-absence data, two of them previously proposed (multiple representations and selecting an increasing percentage of each species' range) and a novel one based on selecting the site where each species has exhibited a higher permanence rate in the past. Multiple representations appear to be a safer strategy than selecting a percentage of range because the former gives priority to rarer species while the latter favours the most widespread.
The most effective strategy was the one based on the permanence rate, indicating that the robustness of reserve networks can be improved by adopting reserve selection procedures that integrate information about the relative value of sites. This strategy was also very efficient, suggesting that the investment made in the monitoring schemes may be compensated for by a lower cost in reserve acquisition
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