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291.
292.
The interaction of water vapor with clean bulk gold surfaces was studied by means of measurement of work function changes. A work function decrease of as much as one volt occurred on exposure of gold to water vapor. Both physical adsorption and chemisorption contributions to this work function decrease could be distinguished. Water was found to chemisorb on the gold with an activation energy of 3 to 9 kcal/mole and had a desorption energy of about 25 kcal/mole. 相似文献
293.
S.?KraftEmail author A.?Günther P.?Wicke B.?Kasch C.?Zimmermann J.?Fortágh 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,35(1):119-123
We describe the realization of atom-optical elements as
magnetic waveguide potentials, beam splitters and gravitational
traps on a microchip. The microchip was produced by electroplating
gold conductors on an aluminium-oxide substrate. The conductors are
30–150 μm wide and allow for the generation of waveguides at
large distances to the chip surface, where surface effects are
negligible. We show that these elements can be integrated on a
single chip to achieve complex atom-optical circuits. 相似文献
294.
Laure?Verret Romain?Goutagny Patrice?Fort Laurène?Cagnon Denise?Salvert Lucienne?Léger Romuald?Boissard Paul?Salin Christelle?Peyron Pierre-Hervé?LuppiEmail author 《BMC neuroscience》2003,4(1):19
Background
Peptidergic neurons containing the melanin-concentrating hormone (MCH) and the hypocretins (or orexins) are intermingled in the zona incerta, perifornical nucleus and lateral hypothalamic area. Both types of neurons have been implicated in the integrated regulation of energy homeostasis and body weight. Hypocretin neurons have also been involved in sleep-wake regulation and narcolepsy. We therefore sought to determine whether hypocretin and MCH neurons express Fos in association with enhanced paradoxical sleep (PS or REM sleep) during the rebound following PS deprivation. Next, we compared the effect of MCH and NaCl intracerebroventricular (ICV) administrations on sleep stage quantities to further determine whether MCH neurons play an active role in PS regulation.Results
Here we show that the MCH but not the hypocretin neurons are strongly active during PS, evidenced through combined hypocretin, MCH, and Fos immunostainings in three groups of rats (PS Control, PS Deprived and PS Recovery rats). Further, we show that ICV administration of MCH induces a dose-dependant increase in PS (up to 200%) and slow wave sleep (up to 70%) quantities.Conclusion
These results indicate that MCH is a powerful hypnogenic factor. MCH neurons might play a key role in the state of PS via their widespread projections in the central nervous system.295.
Fallani L Cataliotti FS Catani J Fort C Modugno M Zawada M Inguscio M 《Physical review letters》2003,91(24):240405
We report the experimental observation of a lensing effect on a Bose-Einstein condensate expanding in a moving 1D optical lattice. The effect of the periodic potential can be described by an effective mass dependent on the condensate quasimomentum. By changing the velocity of the atoms in the frame of the optical lattice, we induce a focusing of the condensate along the lattice direction. The experimental results are compared with the numerical predictions of an effective 1D theoretical model. In addition, a precise band spectroscopy of the system is carried out by looking at the real-space propagation of the atomic wave packet in the optical lattice. 相似文献
296.
Collective excitations of a trapped Bose-Einstein condensate in the presence of a 1D optical lattice
Fort C Cataliotti FS Fallani L Ferlaino F Maddaloni P Inguscio M 《Physical review letters》2003,90(14):140405
We study low-lying collective modes of an elongated 87Rb condensate produced in a 3D magnetic harmonic trap with the addition of a 1D periodic potential which is provided by a laser standing wave along the axial direction. While the transverse breathing mode remains unperturbed, quadrupole and dipole oscillations along the optical lattice are strongly modified. Precise measurements of the collective mode frequencies at different heights of the optical barriers provide a stringent test of the theoretical model recently introduced [M. Kr?mer, Phys. Rev. Lett. 88, 180404 (2002)]]. 相似文献
297.
Effects of coherence in triplet exciton transport are analyzed in the context of measurements of steady-sdtate delayed fluorescence signals from molecular crystals excited through Ronchi rulings. 相似文献
298.
Ada Bottaro Aruffo 《Annali di Matematica Pura ed Applicata》1992,162(1):115-156
Summary
In this work we continue the study of functional inequality already started in [BA1];we study some properties of this condition, especially the connections between functional inequalities with respect to different functional classes and the connections between couples of functions verifying a condition of functional inequality. 相似文献
299.
We discuss the asymptotic behavior of certain models of dissipative systems obtained from a suitable modification of Kac caricature of a Maxwellian gas. It is shown that global equilibria different from concentration are possible if the energy is not finite. These equilibria are distributed like stable laws, and attract initial densities which belong to the normal domain of attraction. If the initial density is assumed of finite energy, with higher moments bounded, it is shown that the solution converges for large-time to a profile with power law tails. These tails are heavily dependent of the collision rule. 相似文献
300.