7,967 research outputs found
Extended Modified Observable Technique for a Multi-Parametric Trilinear Gauge Coupling Estimation at LEP II
This paper describes the extension of the Modified Observables technique in
estimating simultaneously more than one Trilinear Gauge Couplings. The optimal
properties, unbiasedness and consistent error estimation of this method are
demonstrated by Monte Carlo experimentation using four-fermion
final state topologies. Emphasis is given in the determination of the expected
sensitivities in estimating the and
pair of couplings with data from the 183
GeV LEPII run.Comment: (17 pages, 8 figures
Multidimensional Binning Techniques for a Two Parameter Trilinear Gauge Coupling Estimation at LEP II
This paper describes two generalization schemes of the Optimal Variables
technique in estimating simultaneously two Trilinear Gauge Couplings. The first
is an iterative procedure to perform a 2-dimensional fit using the linear terms
of the expansion of the probability density function with respect to the
corresponding couplings, whilst the second is a clustering method of
probability distribution representation in five dimensions. The pair production
of W's at 183 GeV center of mass energy, where one W decays leptonically and
the other hadronically, was used to demonstrate the optimal properties of the
proposed estimation techniques.Comment: (25 pages, 11 figures
Fast Magnetosonic Waves Driven by Gravitational Waves
The propagation of a gravitational wave (GW) through a magnetized plasma is
considered. In particular, we study the excitation of fast magnetosonic waves
(MSW) by a gravitational wave, using the linearized general-relativistic
hydromagnetic equations. We derive the dispersion relation for the plasma,
treating the gravitational wave as a perturbation in a Minkowski background
space-time. We show that the presence of gravitational waves will drive
magnetosonic waves in the plasma and discuss the potential astrophysical
implications.Comment: 12 pages, 2 figures, Astronomy and Astrophysics in pres
: Random Walk Diffusion meets Hashing for Scalable Graph Embeddings
Learning node representations is a crucial task with a plethora of
interdisciplinary applications. Nevertheless, as the size of the networks
increases, most widely used models face computational challenges to scale to
large networks. While there is a recent effort towards designing algorithms
that solely deal with scalability issues, most of them behave poorly in terms
of accuracy on downstream tasks. In this paper, we aim at studying models that
balance the trade-off between efficiency and accuracy. In particular, we
propose , a scalable embedding model that
computes binary node representations.
exploits random walk diffusion probabilities via stable random projection
hashing, towards efficiently computing embeddings in the Hamming space. Our
extensive experimental evaluation on various graphs has demonstrated that the
proposed model achieves a good balance between accuracy and efficiency compared
to well-known baseline models on two downstream tasks
The use of dolomite as foaming agent and its effect on the microstructure of aluminium metal foams—Comparison to titanium hydride
Proceedings of: 8th EUFOAM Conference. Borovets, Bulgaria, 14-16 July 2010.In this paper dolomite MgCa(CO₃)₂ a naturally occurring mineral was demonstrated to be an effective foaming and stabilizing agent for aluminium with several notable advantages relative to the currently used titanium hydride foaming agent. Characteristic cell structures and microstructural features of foams produced with a dolomite foaming agent are examined and the properties of dolomite based foams produced in a one step process are compared with those produced using titanium hydride based process. The most notable structural feature of dolomite based foams is a smaller cell size and thinner cell faces. Foaming with MgCa(CO₃)₂ also gives rise to a marked increase in the stability of molten foams with a large range of foaming temperatures possible, and an almost complete absence of melt drainage even with extended foaming times. Many of these properties are attributed to the cell surfaces being covered by a thin oxide film formed during the foaming process.Publicad
Matching characteristic codes: exploiting two directions
Combining incoming and outgoing characteristic formulations can provide
numerical relativists with a natural implementation of Einstein's equations
that better exploits the causal properties of the spacetime and gives access to
both null infinity and the interior region simultaneously (assuming the
foliation is free of caustics and crossovers). We discuss how this combination
can be performed and illustrate its behavior in the Einstein-Klein-Gordon field
in 1D.Comment: 10 pages, 9 postscript figures. To appear in Int. Journ. of Mod.
Phys.
Green synthesis and characterization of silver nanoparticles produced using 'Arbutus Unedo' leaf extract
Metallic nanoparticles have received great attention from chemists, physicists, biologists and engineers who wish to use them for the development of a new generation of nanodevices. In the present study silver nanoparticles were synthesized from aqueous silver nitrate through a simple and eco-friendly route using leaf broth of Arbutus unedo, which acted as a reductant and stabilizer simultaneously. The aqueous silver ions when exposed to the leaf broth were reduced and stabilized over long periods of time resulting in the green synthesis of surface functionalized silver nanoparticles. The bio-reduced silver nanoparticles were appropriately characterized. The results revealed the formation of single crystalline Ag nanoparticles with a narrow size distribution for each sample. The particles, although discrete, were predominately coated with the organic leaf extract forming small aggregates, which makes them stable over long time periods and highly appropriate for coatings or biotechnology applications.Publicad
On the absence of BPS preonic solutions in IIA and IIB supergravities
We consider the present absence of 31 out of 32 supersymmetric solutions in
supergravity i.e., of solutions describing BPS preons. A recent result
indicates that (bosonic) BPS preonic solutions do not exist in type IIB
supergravity. We reconsider this analysis by using the G-frame method, extend
it to the IIA supergravity case, and show that there are no (bosonic) preonic
solutions for type IIA either. For the classical D=11 supergravity no
conclusion can be drawn yet, although the negative IIA results permit
establishing the conditions that preonic solutions would have to satisfy. For
supergravities with `stringy' corrections, the existence of BPS preonic
solutions remains fully open.Comment: plain latex, 12 pages Minor misprints corrected. Published in JHEP 09
(2006) 00
Hidden geometric correlations in real multiplex networks
Real networks often form interacting parts of larger and more complex
systems. Examples can be found in different domains, ranging from the Internet
to structural and functional brain networks. Here, we show that these multiplex
systems are not random combinations of single network layers. Instead, they are
organized in specific ways dictated by hidden geometric correlations between
the individual layers. We find that these correlations are strong in different
real multiplexes, and form a key framework for answering many important
questions. Specifically, we show that these geometric correlations facilitate:
(i) the definition and detection of multidimensional communities, which are
sets of nodes that are simultaneously similar in multiple layers; (ii) accurate
trans-layer link prediction, where connections in one layer can be predicted by
observing the hidden geometric space of another layer; and (iii) efficient
targeted navigation in the multilayer system using only local knowledge, which
outperforms navigation in the single layers only if the geometric correlations
are sufficiently strong. Our findings uncover fundamental organizing principles
behind real multiplexes and can have important applications in diverse domains.Comment: Supplementary Materials available at
http://www.nature.com/nphys/journal/v12/n11/extref/nphys3812-s1.pd
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