1,033 research outputs found
Demonstration of fundamental mode only propagation in highly multimode fibre for high power EDFAs
The use of short lengths of large core phosphate glass fibre, doped with high
concentrations of Er or Er:Yb represents an attractive route to achieving high
power erbium doped fibre amplifiers (EDFAs) and lasers (EDFLs). With the aim of
investigating the potential of achieving diffraction limited output from such
large core fibres, we present experimental results of fundamental mode
propagation through a 20 cm length of passive 300 micrometer core multimode
fibre when the input is a well-aligned Gaussian beam. Through careful control
of fibre geometry, input beam parameters and alignment, we measured an output M
squared of 1.1 + - 0.05. The fibre had a numerical aperture of 0.389, implying
a V number of 236.8. To our knowledge, this is the largest core fibre through
which diffraction limited fundamental mode propagation has been demonstrated.
Although the results presented here relate to undoped fibre, they do provide
the practical basis for a new generation of EDFAs and EDFLs.Comment: 5 figure
The relationship between SNPS in the genes of TLR signal transduction pathway downstream elements and rheumatoid arthritis susceptibility
Toll-like receptors (TLRs) play an important role in the induction and regulation of the innate immune system or adaptive immune responses. Genetic variations within human TLRs have been reported to be associated with rheumatoid arthritis (RA). This study was conducted to investigate correlation between SNP of downstream mononucleotide in signal transduction of Toll-like receptors and predisposing genes of RA. There was obviously correlative between single nucleotide polymorphism and predisposing genes of RA. G-type of IL-1RAP rs766442 may be protecting genes of RA, while T-type alleles of IL-6R rs11265618 and IL-1RAP rs766442 may be susceptible genes of RA. In conclusion, the studies on the nucleis acid polymorphism in TLRs signal pathway contribute to disclose genes’ influence on the attack mechanism of RA, early diagnosis and treatment of RA.Толл-подобные рецепторы (TLRs) играют важную роль в индукции и регуляции врожденной иммунной системы или адаптивных иммунных ответах. Показано, что что генетическая изменчивость TLRs человека связана с ревматоидным артритом (РА). Целью настоящей работы было изучение корреляций между однонуклеотидным полиморфизмом в сигнальной трансдукции TLRs и генами предрасположенности к РА. G-тип IL-1RAP rs766442 могут быть генами, предохраняющими от РА, в то время как аллели T-типа IL-6R rs11265618 и IL-1RAP rs766442 могут быть генами чувствительности к РА. Изучение полиморфизма нуклеиновых кислот в сигнальном пути TLRs может внести вклад в выявление участия генов в механизмах приступов РА, раннюю диагностику и лечение РА.The study was supported by Shandong Province young scientist in incentive fund (Grant № 2006BS03018) and National Natural Science Foundation of China (Grant № 30801025)
Percolation on two- and three-dimensional lattices
In this work we apply a highly efficient Monte Carlo algorithm recently
proposed by Newman and Ziff to treat percolation problems. The site and bond
percolation are studied on a number of lattices in two and three dimensions.
Quite good results for the wrapping probabilities, correlation length critical
exponent and critical concentration are obtained for the square, simple cubic,
HCP and hexagonal lattices by using relatively small systems. We also confirm
the universal aspect of the wrapping probabilities regarding site and bond
dilution.Comment: 15 pages, 6 figures, 3 table
Search for Invisible Decays of and in and
Using a data sample of decays collected with the BES
II detector at the BEPC, searches for invisible decays of and
in to and are performed.
The signals, which are reconstructed in final states, are used
to tag the and decays. No signals are found for the
invisible decays of either or , and upper limits at the 90%
confidence level are determined to be for the ratio
and for . These are the first
searches for and decays into invisible final states.Comment: 5 pages, 4 figures; Added references, Corrected typo
Observation of Two New N* Peaks in J/psi -> and Decays
The system in decays of is limited to be
isospin 1/2 by isospin conservation. This provides a big advantage in studying
compared with and experiments which mix
isospin 1/2 and 3/2 for the system. Using 58 million decays
collected with the Beijing Electron Positron Collider, more than 100 thousand
events are obtained. Besides two well known
peaks at 1500 MeV and 1670 MeV, there are two new, clear peaks in
the invariant mass spectrum around 1360 MeV and 2030 MeV. They are the
first direct observation of the peak and a long-sought "missing"
peak above 2 GeV in the invariant mass spectrum. A simple
Breit-Wigner fit gives the mass and width for the peak as MeV and MeV, and for the new peak above 2 GeV
as MeV and MeV, respectively
On manifolds with nonhomogeneous factors
We present simple examples of finite-dimensional connected homogeneous spaces
(they are actually topological manifolds) with nonhomogeneous and nonrigid
factors. In particular, we give an elementary solution of an old problem in
general topology concerning homogeneous spaces
On the deflection of asteroids with mirrors
This paper presents an analysis of an asteroid deflection method based on multiple solar concentrators. A model of the deflection through the sublimation of the surface material of an asteroid is presented, with simulation results showing the achievable orbital deflection with, and without, accounting for the effects of mirror contamination due to the ejected debris plume. A second model with simulation results is presented analyzing an enhancement of the Yarkovsky effect, which provides a significant deflection even when the surface temperature is not high enough to sublimate. Finally the dynamical model of solar concentrators in the proximity of an irregular celestial body are discussed, together with a Lyapunov-based controller to maintain the spacecraft concentrators at a required distance from the asteroid
Decay and Right-handed Top-bottom Charged Current
We introduce an anomalous top quark coupling (right-handed current) into
Standard Model Lagrangian. Based on this, a more complete calculation of decay including leading log QCD corrections from to
in addition to corrections from to is given. The inclusive decay
rate is found to be suppressed comparing with the case without QCD running from
to except at the time of small values of . e.g. when
, it is only of the value given before. As
goes smaller, this contribution is an enhancement like standard model case.
From the newly experiment of CLEO Collaboration, strict restrictions to
parameters of this top-bottom quark coupling are found.Comment: 20 Pages, 2 figures( ps file uuencoded)
Graviton production from extra dimensions
Graviton production due to collapsing extra dimensions is studied. The
momenta lying in the extra dimensions are taken into account. A -dimensional
background is matched to an effectively four-dimensional standard radiation
dominated universe. Using observational constraints on the present
gravitational wave spectrum, a bound on the maximal temperature at the
beginning of the radiation era is derived. This expression depends on the
number of extra dimensions, as well as on the -dimensional Planck mass.
Furthermore, it is found that the extra dimensions have to be large.Comment: LaTeX file, 14 pages, 4 figure
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