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71.
72.
Optimal lower bounds for cubature error on the sphere 总被引:6,自引:1,他引:5
We show that the worst-case cubature error E(Qm;Hs) of an m-point cubature rule Qm for functions in the unit ball of the Sobolev space Hs=Hs(S2),s>1, has the lower bound , where the constant cs is independent of Qm and m. This lower bound result is optimal, since we have established in previous work that there exist sequences of cubature rules for which with a constant independent of n. The method of proof is constructive: given the cubature rule Qm, we construct explicitly a ‘bad’ function fmHs, which is a function for which Qmfm=0 and . The construction uses results about packings of spherical caps on the sphere. 相似文献
73.
A novel convenient synthetic route for poly-functional 21-monothiatetraphenylporphyrins of the type A4 und AB3 having base labile substituents in meso position was developed. Using this method a series of symmetric and asymmetric 21-thiaporphyrins containing different functional groups at the meso position is reported. The new products were characterized by NMR, UV-Vis and mass spectroscopy. 相似文献
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76.
Kerstin Zab Detlev Joachimi Eva Novotna Siegmar Diele Carsten Tschierske 《Liquid crystals》1995,18(4):631-637
Various trimeric co-oligomers combining 2-phenyl-1,3,4-thiadiazole mesogenic moieties with a biphenyl mesogenic moiety were synthesized and their mesomorphic behaviour investigated by polarizing microscopy, calorimetry and X-ray scattering. Such co-oligomeric structures provide an opportunity to combine different mesogenic units. Thus readily accessible homochiral biphenyl mesogenic units were connected with thiadiazole mesogenic units leading to an oligomeric liquid crystal material with ferroelectric properties. 相似文献
77.
Juha?M.?Saarela Torbj?rn?L?fqvist Kerstin?Ramser Per?Gren Erik?Olson Jan?Niemi Mikael?Sj?dahl 《Central European Journal of Physics》2010,8(2):235-241
This study is focused on exploring the feasibility of an all-optic surface scanning method in determining the size and position
of a submerged, laser generated, optoacoustic (OA) source. The optoacoustic effect in this case was generated when the absorption
of a short electromagnetic pulse in matter caused a dielectric breakdown, a plasma emission flash and a subsequent acoustic
wave. In the experiment, a laser pulse with λ = 1064 nm and 12 ns pulse length was aimed at a volume of deionized water. When
the laser beam was focused by a f = 16 mm lens, a single dielectric breakdown spot occurred. When a f = 40 mm was used several breakdowns in a row were induced. The breakdowns were photographed using a double shutter camera.
The acoustic wave generated by the dielectric breakdowns were detected at a point on the water surface using a laser Doppler
vibrometer (LDV). First, the LDV signal was used to calculate the speed of sound with an accuracy of 10 m/s. Secondly, the
location and length of the dielectric breakdown was calculated with an accuracy of 1 mm. The calculated position matched the
breakdown location recorded by a camera. The results show that it is possible to use LDV surface measurements from a single
spot to determine both the position and length of the OA source as well as the speed of sound in the medium. Furthermore,
the LDV measurements also show a secondary peak that originates from the OA source. To unravel the origin and properties of
this interesting feature, further investigations are necessary 相似文献
78.
Background
Infections with respiratory viruses can activate the innate immune response - an important host defence mechanism in the early stage of viral infection. Interferon (IFN) release, triggered by virus infection, is an important factor in establishing an antiviral state, where IFN activation occurs prior to the onset of the adaptive immune response. 相似文献79.
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