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31.
32.
Oscar Blasco 《Mathematische Zeitschrift》1988,199(1):109-114
Supported by the Grant C.A.I.C.Y.T. n 85-0338 相似文献
33.
34.
35.
In this article we obtain the boundedness of the periodic, discrete and ergodic
bilinear Hilbert transform, from
,
where
1$, and $p_3\ge 1$" align="middle" border="0">
. The main techniques are a bilinear version of the transference method of Coifman and Weiss and certain discretization of bilinear operators. In the periodic case, we also obtain the boundedness for
相似文献
36.
37.
Two new families of completely integrable perturbations of the N-dimensional isotropic harmonic oscillator Hamiltonian are presented. Such perturbations depend on arbitrary functions and N free parameters and their integrals of motion are explicitly constructed by making use of an underlying h6-coalgebra symmetry. Several known integrable Hamiltonians in low dimensions are obtained as particular specializations of the general results here presented. An alternative route for the integrability of all these systems is provided by a suitable canonical transformation which, in turn, opens the possibility of adding (N−1) ‘Rosochatius’ terms that preserve the complete integrability of all these models. 相似文献
38.
The design of a fiber coupler for high efficiency light coupling to silicon sandwiched slot waveguides is reported. The proposed fiber coupler is based on the inverted taper approach. Parameters have been optimized to maximize coupling efficiency for λ = 1550 nm and TM polarization. Maximum coupling efficiencies of 93% for a inverted taper length of 150 μm and a inverted taper tip width of 40 nm have been obtained by means of the overlap integral and 3D beam propagation method (BPM) simulations. 相似文献
39.
The air quality in the Aragón valley, in the central Pyrenees, has been assessed by evaluation of lichen biodiversity and
mapped by elaboration of the Index of Air Purity (IAP) based on observations of the presence and abundance of eight kinds
of lichen with different sensitivity to air pollution. The IAP values obtained have been compared with quantitative analytical
measures of 16 PAHs in the lichen Evernia prunastri, because this species was associated with a wide range of traffic exposure and levels of urbanization. Analyses of PAHs were
carried out by the DSASE method followed by an SPE clean-up step and GC–MS analysis. The concentration of total PAHs found
in lichen samples from the Aragón valley ranged from 692 to 6420 ng g−1 and the PAHs profile showed predominance of compounds with three aromatic rings. The influence of the road traffic in the
area has been shown because values over the median concentration of PAHs (>1092 ng g−1), percentage of combustion PAHs (>50%), and equivalent toxicity (>169) were found in lichens collected at places exposed
to the influence of traffic. The combination of both methods suggests IAP as a general method for evaluating the air pollution
referenced to PAHs because it can be correlated with the content of combustion PAHs and poor lichen biodiversity can be partly
explained by the air pollution caused by specific PAHs.
Figure Map of the air pollution level in the Aragón valley (Pyrenees) based on the Index of Air Purity (IAP) calculation (lichen
biodiversity) 相似文献
40.
Dixon IM Lopez F Tejera AM Estève JP Blasco MA Pratviel G Meunier B 《Journal of the American Chemical Society》2007,129(6):1502-1503