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151.
Déchirures de variétés de dimension trois et la conjecture de Nash de rationalité en dimension trois
Sans résumé
Dédié à Heisuke Hironaka 相似文献
152.
De Lamo Marin S Martens T Mioskowski C Royer J 《The Journal of organic chemistry》2005,70(25):10592-10595
[reaction: see text] A new method of deprotection of N-p-methoxyphenylamines using anodic oxidation in acidic medium is presented. The process furnishes a high yield of amine and is compatible with several oxidable functional groups. 相似文献
153.
154.
The characterisation of the physical state of frozen and freeze dried biological products delivers powerful information for freeze-drying process optimisation. The influence of lactic acid bacterial cell size, shape and concentration on collapse temperature of concentrated bacterial suspensions was investigated. Lactobacillus bulgaricus (long rods), and Streptococcus thermophilus (small spherical cells) were used as cellular models for this study. Whatever the strain, when lactic acid bacterial cells were added to protective solutions, the collapse temperature increased, thus allowing the use of higher sublimation temperatures during primary drying than expected from the protective medium alone. Moreover, the higher the cell concentration, the greater the effect, linear relationships existing between the collapse temperatures and the total dried matter. Cells of both strains gave a kind of robustness to the freeze-dried product, but the increase observed in collapse temperature was considerably higher (3 - 5 degree C) for L. bulgaricus compared to S. thermophilus. This result was ascribed to the different size and shape of the strains. 相似文献
155.
We study the suppression of the small-scale power spectrum due to the decay of charged matter to dark matter prior to recombination. Prior to decay, the charged particles couple to the photon-baryon fluid and participate in its acoustic oscillations. However, after these charged particles decay to neutral dark matter, the photon-baryon fluid is coupled only gravitationally to the newly created dark matter. This generically leads to suppression of power on length scales that enter the horizon prior to decay. For decay times of approximately 3.5 yr this leads to suppression of power on subgalactic scales, bringing the observed number of galactic substructures in line with observation. Decay times of a few years are possible if the dark matter is purely gravitationally interacting, such as the gravitino in supersymmetric models or a massive Kaluza-Klein graviton in models with universal extra dimensions. 相似文献
156.
We have measured the intensity dependent rate and frequency shift of a photoassociation transition in a quantum degenerate gas of 7Li. The rate increases linearly with photoassociation laser intensity for low intensities, whereas saturation is observed at higher intensities. The measured rates and shifts agree reasonably well with theory within the estimated systematic uncertainties. Several theoretically predicted saturation mechanisms are discussed, but a theory in which saturation arises because of quantum mechanical unitarity agrees well with the data. 相似文献
157.
Nonlocal shaping effects in the time or spectral profiles of an entangled photon pair emerging from a pulsed parametric down-converter are observed by spectrally or temporally filtering one of the twin beams. In particular, we demonstrate the appearance of fourth-order ("ghost") interference fringes in the spectrum of one beam conditioned by photodetection at the output of an unbalanced Michelson interferometer placed in the path of the other beam. The coherence time of the pump is the limiting factor for the sharpness of the details in the shaped biphoton spectrum. 相似文献
158.
The full exploitation of single-molecule spectroscopy in disordered systems is often hampered by spectral diffusion processes of the optical transitions due to structural fluctuations in the local environment of the probe molecule which leads to temporal averaging of the signal. Multivariate statistical pattern recognition techniques, originally developed for single-molecule cryoelectron microscopy, allow us to retrieve detailed information from optical single-molecule spectra. As an example, we present the phonon side band of the B800 excitations of the light-harvesting 2 (LH2) complex from Rhodospirillum molischianum, revealing the electron-phonon coupling strength for these transitions. The measured Debye-Waller factors, ranging from 0.4 to 0.9, fall in the regime of weak electron-phonon coupling. 相似文献
159.
A fast algorithm for dealing with multiplicative stochastic processes such as dielectric relaxation is developed. This technique allows us to get a straightforward evaluation of the effects of non-linearity, expecially non-Gaussian behaviour. Its use jointly to computer “experiments” on non-Gaussian behaviour is shown to be of basic importance for establishing a new approach to molecular dynamics in terms of non-linear models. 相似文献
160.
Iuliu Pop Natalia Dihoiu Marin Coldea 《Journal of Physics and Chemistry of Solids》1982,43(2):125-128
The magnetic behaviour of the intermetallic compounds Gd2Ni17?xAlx, (0?x?2) has been investigated both in the ferrimagnetic and paramagnetic regions. The unusual temperature dependence of the intensity of magnetization may be interpreted as a second order phase transition of order-order type, i.e. from colinear to non-colinear ferrimagnetic structure. 相似文献