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61.
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63.
Altewischer E Genet C van Exter MP Woerdman JP Alkemade PF van Zuuk A van der Drift EW 《Optics letters》2005,30(1):90-92
We report polarization tomography experiments on metallic nanohole arrays with square and hexagonal symmetry. As a main result we find that a fully polarized input beam is partly depolarized after transmission through a nanohole array. This loss of polarization coherence is found to be anisotropic; i.e., it depends on the polarization state of the input beam. The depolarization is ascribed to a combination of two factors: (i) the nonlocal response of the array as a result of surface-plasmon propagation and (ii) the non-plane-wave nature of a practical input beam. 相似文献
64.
It has been observed that noble gases, such as helium, neon and argon produce heat evolution when contacted with Pd powder partially saturated with hydrogen. These phenomena have been studied with flow-through adsorption microcalorimetry. The observed exothermic effects are comparable to those usually associated with the heat of sorption of hydrogen in palladium. It is suggested that the noble gases displace the adsorbed H species from the surface of Pd, causing their reabsorption in the Pd lattice with the exothermic heat of PdH bonds formation, or the formation of H2, both heat evolutions being observed with a flow-through microcalorimeter. 相似文献
65.
The effect of substances as possible inhibitors of the K+(Na+)/H+ exchanger in the human red cell membrane has been tested on the (ouabain+bumetanide+EGTA)-resistant K+ influx in both physiological (HIS) and low ionic strength (LIS) solution with tracer kinetic methods. It is demonstrated that high concentrations of quinacrine (1 mM) and chloroquine (2 mM) inhibit the residual K+ influx in LIS solution to 60% and 85%, respectively, but activate it in HIS solution. Thus, chloroquine suppressed the 10-fold LIS-induced activation of the flux nearly completely. Amiloride derivatives were able to inhibit the K+ influx in both HIS and LIS solution. EIPA (75 microM) reduced the flux by about 20% and 55% in HIS and LIS solution, respectively. Newly developed drugs (HOE 642, 1 mM; HOE 694, 0.5 mM) designed to inhibit Na+/H+ exchanger isoforms showed an inhibition of the residual K+ influx of 40% and 33% in HIS and 65% and 44% in LIS solution, respectively, without haemolysis. The inhibitory effect of HOE 642 persisted in HIS (24%) and LIS (48%) solutions when Cl- was replaced by CH3SO4-. The K(+)-Cl- cotransport inhibitor DIOA (100 microM) stimulated the residual K+ influx in both solutions. It is, therefore, concluded that the K(+)-Cl- cotransporter does not contribute to the residual K+ influx both in HIS and LIS media. Okadaic acid decreased the residual K+ influx by 40% and 25% in HIS and LIS solution, respectively, showing that the residual K+ influx is affected by phosphatases like other ion transport pathways. The results show that the residual K+ influx can be decreased further by inhibiting the K+(Na+)/H+ exchanger. It remains still unclear to what extent the K+(Na+)/H+ exchanger is inhibited by the different substances used. However, the ground state membrane permeability for K+ is much smaller than assumed so far. 相似文献
66.
Alexopoulos T Arenton M Barbosa RF Barker AR Bellantoni L Bellavance A Blucher E Bock GJ Cheu E Childress S Coleman R Corcoran MD Cox B Erwin AR Ford R Glazov A Golossanov A Graham J Hamm J Hanagaki K Hsiung YB Huang H Jejer V Jensen DA Kessler R Kobrak HG Kotera K LaDue J Ledovskoy A McBride PL Monnier E Nelson KS Nguyen H Niclasen R Prasad V Qi XR Ramberg EJ Ray RE Ronquest M Santos E Shanahan P Shields J Slater W Smith D Solomey N Swallow EC Toale PA Tschirhart R Wah YW Wang J White HB 《Physical review letters》2004,93(18):181802
We present a determination of the Cabibbo-Kobayashi-Maskawa parameter |V(us)| based on new measurements of the six largest K(L) branching fractions and semileptonic form factors by the KTeV (E832) experiment at Fermilab. We find |V(us)|=0.2252+/-0.0008(KTeV)+/-0.0021(ext), where the errors are from KTeV measurements and from external sources. We also use the measured branching fractions to determine the CP violation parameter |eta(+-)|=(2.228+/-0.005(KTeV)+/-0.009(ext))x10(-3). 相似文献
67.
We present experimental evidence for the spontaneous formation of a macroscopic spin polarization in overlapping regions of two independent Bose-Einstein condensates produced in different hyperfine states of 87Rb. The condensates are independent in the sense that we do not explicitly introduce a relative phase between them. A single "spin-tip" pulse maps the transverse spin polarization into longitudinal spin polarization, and the atomic density distributions are measured with a Stern-Gerlach imaging method. The resulting matter-wave interference patterns are anticorrelated. 相似文献
68.
We study the elasticity of a two-dimensional random network of rigid rods ("Mikado model"). The essential features incorporated into the model are the anisotropic elasticity of the rods and the random geometry of the network. We show that there are three distinct scaling regimes, characterized by two distinct length scales on the elastic backbone. In addition to a critical rigidity percolation region and a homogeneously elastic regime we find a novel intermediate scaling regime, where the elasticity is dominated by bending deformations. 相似文献
69.
Alavi-Harati A Alexopoulos T Arenton M Arisaka K Barbosa RF Barker AR Barrio M Bellantoni L Bellavance A Blucher E Bock GJ Bown C Bright S Cheu E Coleman R Corcoran MD Cox B Erwin AR Escobar CO Ford R Glazov A Golossanov A Gouffon P Graham J Hamm J Hanagaki K Hsiung YB Huang H Jejer V Jensen DA Kessler R Kobrak HG Kotera K LaDue J Lai N Ledovskoy A McBride PL Monnier E Nelson KS Nguyen H Prasad V Qi XR Quinn B Ramberg EJ Ray RE Santos E Senyo K Shanahan P Shields J Slater W Solomey N Swallow EC 《Physical review letters》2003,90(14):141801
The KTeV experiment at Fermilab has isolated a total of 132 events from the rare decay K(L)-->e+ e- mu+ mu-, with an estimated background of 0.8 events. The branching ratio of this mode is determined to be [2.69+/-0.24(stat)+/-0.12(syst)]x10(-9), with a radiative cutoff of M(2)(ee mu mu)/M(2)(K)>0.95. The first measurement using this mode of the parameter alpha from the D'Ambrosio-Isidori-Portolès (DIP) model of the K(L)gamma*gamma* vertex yields a result of -1.59+/-0.37, consistent with values obtained from other decay modes. Because of the limited statistics, no sensitivity is found to the DIP parameter beta. We use this decay mode to set limits on CP and lepton violation. 相似文献
70.
Finite element approximation of spectral problems with Neumann boundary conditions on curved domains
This paper deals with the finite element approximation of the spectral problem for the Laplace equation with Neumann boundary conditions on a curved nonconvex domain . Convergence and optimal order error estimates are proved for standard piecewise linear continuous elements on a discrete polygonal domain in the framework of the abstract spectral approximation theory.