549 research outputs found
Effect of additives on lithium doped magnesium oxide catalysts used in the oxidative coupling of methane
It has been found that it is possible to improve the activity and stability for the oxidative coupling of methane of a Li/MgO catalyst by the addition of small amounts of the oxides of various transition and rare earth metals. A number of these additives, e.g. SnO2, TiO2, Dy2O3 and Tb4O7, caused little or no difference in the selectivity to C2 products achieved with the resultant catalyst while considerably lowering the temperatures required to give the optimum yields of C2 products. Several other additives caused slight improvements (e.g. La2O3 and NiO) without changing the selectivity and some lowered the temperature for a particular conversion (e.g. CoO, MnO2, PbO and Bi2O3). A number of aspects of some of these catalysts are examined, including the nature of the phases present in the calcined materials, the decomposition of carbonate phases in the catalysts, the effect of promoter concentration and the ageing behaviour under oxidative coupling conditions. A comparison of the various systems shows that the Li/Sn/MgO is an extremely promising catalyst system for the oxidative coupling of methane
Draft guidelines concerning E&D issues: The TELSCAN handbook of design guidelines for usability of systems by elderly and disabled drivers and travellers. Version 2
Draft guidelines concerning E&D issues: The TELSCAN handbook of design guidelines for usability of systems by elderly and disabled drivers and travellers. Version
Signals of neutralinos and charginos from gauge boson fusion at the CERN Large Hadron Collider
We point out that interesting signals of the non-strongly interacting sector
of the supersymmetric standard model arise from the production of charginos and
neutralinos via vector boson fusion (VBF) at the Large Hadron Collider (LHC).
In particular, if R-parity is violated, the hadronically quiet signals of
charginos and neutralinos through direct production get considerably
suppressed. We show that in such cases, the VBF channel can be useful in
identifying this sector through clean and background-free final states.Comment: 10 pages Latex, 8 figures, minor changes in text and few references
added, to be published in Phys. Rev.
Like Sign Dilepton Signature for R-Parity Violating SUSY Search at the Tevatron Collider
The like sign dileptons provide the most promising signature for
superparticle search in a large category of -parity violating SUSY models.
We estimate the like sign dilepton signals at the Tevatron collider, predicted
by these models, over a wide region of the MSSM parameter space. One expects an
unambiguous signal upto a gluino mass of GeV ( GeV) with
the present (proposed) accumulated luminosity of .Comment: 12 page LaTeX file; 5 figures available upon request from the autho
Bottom-Tau Unification in SUSY SU(5) GUT and Constraints from b to s gamma and Muon g-2
An analysis is made on bottom-tau Yukawa unification in supersymmetric (SUSY)
SU(5) grand unified theory (GUT) in the framework of minimal supergravity, in
which the parameter space is restricted by some experimental constraints
including Br(b to s gamma) and muon g-2. The bottom-tau unification can be
accommodated to the measured branching ratio Br(b to s gamma) if superparticle
masses are relatively heavy and higgsino mass parameter \mu is negative. On the
other hand, if we take the latest muon g-2 data to require positive SUSY
contributions, then wrong-sign threshold corrections at SUSY scale upset the
Yukawa unification with more than 20 percent discrepancy. It has to be
compensated by superheavy threshold corrections around the GUT scale, which
constrains models of flavor in SUSY GUT. A pattern of the superparticle masses
preferred by the three requirements is also commented.Comment: 21pages, 6figure
Detailed insights into pan-European population structure and inbreeding in wild and hatchery Pacific oysters (Crassostrea gigas) revealed by genome-wide SNP data.
Cultivated bivalves are important not only because of their economic value, but also due to their impacts on natural ecosystems. The Pacific oyster (Crassostrea gigas) is the world's most heavily cultivated shellfish species and has been introduced to all continents except Antarctica for aquaculture. We therefore used a medium-density single nucleotide polymorphism (SNP) array to investigate the genetic structure of this species in Europe, where it was introduced during the 1960s and has since become a prolific invader of coastal ecosystems across the continent. We analyzed 21,499 polymorphic SNPs in 232 individuals from 23 localities spanning a latitudinal cline from Portugal to Norway and including the source populations of Japan and Canada. We confirmed the results of previous studies by finding clear support for a southern and a northern group, with the former being indistinguishable from the source populations indicating the absence of a pronounced founder effect. We furthermore conducted a large-scale comparison of oysters sampled from the wild and from hatcheries to reveal substantial genetic differences including significantly higher levels of inbreeding in some but not all of the sampled hatchery cohorts. These findings were confirmed by a smaller but representative SNP dataset generated using restriction site-associated DNA sequencing. We therefore conclude that genomic approaches can generate increasingly detailed insights into the genetics of wild and hatchery produced Pacific oysters
Random forest for gene selection and microarray data classification
A random forest method has been selected to perform both gene selection and classification of the microarray data. In this
embedded method, the selection of smallest possible sets of genes with lowest error rates is the key factor in achieving highest
classification accuracy. Hence, improved gene selection method using random forest has been proposed to obtain the smallest
subset of genes as well as biggest subset of genes prior to classification. The option for biggest subset selection is done to assist
researchers who intend to use the informative genes for further research. Enhanced random forest gene selection has performed
better in terms of selecting the smallest subset as well as biggest subset of informative genes with lowest out of bag error rates
through gene selection. Furthermore, the classification performed on the selected subset of genes using random forest has lead to
lower prediction error rates compared to existing method and other similar available methods
Effects of new physics in neutrino oscillations in matter
A new flavor changing electron neutrino interaction with matter would always
dominate the nu_e oscillation probability at sufficiently high neutrino
energies. Being suppressed by theta_{13}, the energy scale at which the new
effect starts to be relevant may be within the reach of realistic experiments,
where the peculiar dependence of the signal with energy could give rise to a
clear signature in the nu_e --> nu_tau channel. The latter could be observed by
means of a coarse large magnetized detector by exploiting tau --> mu decays. We
discuss the possibility of identifying or constraining such effects with a high
energy neutrino factory. We also comment on the model independent limits on
them.Comment: 11 pages, 5 figure
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