1,163 research outputs found

    A Database for Case Histories and Numerical Modelling

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    This paper deals with a bibliographic database dedicated to the comparison between numerical results and in situ measurements for geotechnical structures. This database, called MOMIS, has been developed by LCPC and ECN for several years. To date, it comprises a total of 416 case histories. The generation of MOMIS has relied on a technologic watch in the field of numerical modelling. The database can be used to highlight modelling principles (in order to provide a guide for good modelling practice to users) and deviations between results given by numerical models and values measured on actual geotechnical structures. It also reflects the evolution of the accuracy of numerical computations

    Guided Quasicontinuous Atom Laser

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    We report the first realization of a guided quasicontinuous atom laser by rf outcoupling a Bose-Einstein condensate from a hybrid optomagnetic trap into a horizontal atomic waveguide. This configuration allows us to cancel the acceleration due to gravity and keep the de Broglie wavelength constant at 0.5 μ\mum during 0.1 s of propagation. We also show that our configuration, equivalent to pigtailing an optical fiber to a (photon) semiconductor laser, ensures an intrinsically good transverse mode matching.Comment: version published in Phys. Rev. Lett. 97, 200402 (2006

    Theoretical tools for atom laser beam propagation

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    We present a theoretical model for the propagation of non self-interacting atom laser beams. We start from a general propagation integral equation, and we use the same approximations as in photon optics to derive tools to calculate the atom laser beam propagation. We discuss the approximations that allow to reduce the general equation whether to a Fresnel-Kirchhoff integral calculated by using the stationary phase method, or to the eikonal. Within the paraxial approximation, we also introduce the ABCD matrices formalism and the beam quality factor. As an example, we apply these tools to analyse the recent experiment by Riou et al. [Phys. Rev. Lett. 96, 070404 (2006)]

    Fourfold oscillations and anomalous magnetic irreversibility of magnetoresistance in the non-metallic regime of Pr1.85Ce0.15CuO4

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    Using magnetoresistance measurements as a function of applied magnetic field and its direction of application, we present sharp angular-dependent magnetoresistance oscillations for the electron-doped cuprates in their low-temperature non-metallic regime. The presence of irreversibility in the magnetoresistance measurements and the related strong anisotropy of the field dependence for different in-plane magnetic field orientations indicate that magnetic domains play an important role for the determination of electronic properties. These domains are likely related to the stripe phase reported previously in hole-doped cuprates.Comment: 11 pages, 5 figure

    Nietzsche dans l’«Etoile de la Rédemption» de Rosenzweig. La figure historique de l’athéisme véritable

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    In this major work, Franz Rosenzweig delivers a startling reading of Nietzsche’s atheism as the first true atheism of philosophical history. While Hegel and other philosophers before him indissolubly bound God with the world, thereby preventing any true understanding of divine existence, Nietzsche puts an end to all of God’s substitutes and confronts God himself, that is, His intolerable liberty.  Franz Rosenzweig nos ofrece en su obra maestra, La estrella de la Redención, una lectura original del ateísmo de Nietzsche, ya que lo considera como el primer ateo genuino de la historia de la filosofía. Mientras Hegel, así como toda la tradición filosófica que le precede, une de manera indisoluble a Dios y al mundo, impidiendo así una comprensión verdadera de la existencia divina, Nietzsche termina con todos los substitutos de Dios y afronta a Dios mismo, es decir, a su intolerable libertad

    Constraints on a vacuum energy from both SNIa and CMB temperature observations

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    We investigate the cosmic thermal evolution with a vacuum energy which decays into photon at the low-redshift. We assume that the vacuum energy is a function of the scale factor that increases toward the early universe. We put on the constraints using recent observations of both type Ia supernovae (SNIa) by Union-2 compilation and the cosmic microwave background (CMB) temperature at the range of the redshift 0.01 < z < 3. From SNIa, we find that the effects of a decaying vacuum energy on the cosmic expansion rate should be very small but could be possible for z < 1.5. On the other hand, we obtain the severe constraints for parameters from the CMB temperature observations. Although the temperature can be still lower than the case of the standard cosmological model, it should only affect the thermal evolution at the early epoch.Comment: 9 pages, 3 figures, 1 tables, submitted to Advances in Astronom

    Impact of infection status and cyclosporine on voriconazole pharmacokinetics in an experimental model of cerebral scedosporiosis

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    Cerebral Scedosporium infections usually occur in lung transplant recipients as well as in immunocompetent patients in the context of near-drowning. Voriconazole is the first-line treatment. The diffusion of voriconazole through the blood-brain barriers in the context of cerebral infection and cyclosporine administration is crucial and remains a matter of debate. To address this issue, the pharmacokinetics of voriconazole were assessed in the plasma, cerebrospinal fluid (CSF), and brain, in an experimental model of cerebral scedosporiosis in rats receiving or not cyclosporine. A single dose of voriconazole (30 mg/kg, i.v.) was administrated to six groups of rats randomized according to the infection status and the cyclosporine dosing regimen (no cyclosporine, a single dose or three doses 15 mg/kg each). Voriconazole concentrations in plasma, CSF, and brain samples were quantified using UPLC-MS/MS and HPLC-UV methods and documented up to 48 hours after administration. Pharmacokinetic parameters were estimated using a non-compartmental approach. Voriconazole pharmacokinetic profiles were similar for plasma, CSF, and the brain in all groups studied. Voriconazole Cmax and AUC0=&gt;48h were significantly higher in the plasma than in the CSF (CSF/plasma ratio, median [range] = 0.5 [0.39-0.55] for AUC0=&gt;48h and 0.47 [0.35 and 0.75] for Cmax). Cyclosporine administration was significantly associated with an increase in voriconazole exposure in the plasma, CSF, and brain. In the plasma but not in the brain, an interaction between the infection and cyclosporine administration reduced the positive impact of cyclosporine on voriconazole exposure. Together these results emphasize the impact of cyclosporine on the brain voriconazole exposure

    Effects of structural factors on the pi-dimerization and/or disproportionation of the cation radical of extended TTF containing thiophene-based pi-conjugated spacers.

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    The electrochemical and chemical oxidation of extended TTF 4 and 5 are analysed by cyclic voltammetry, Visible/NIR and ESR spectroscopies, and the X-ray structures of the new salts 5·BF4(CH2Cl2) and 4·ClO4(THF)1/2 are presented. The effects of structural factors on the π-dimerization or the disproportionation reaction of the cation radical are shown. The oxidation of compound 4 presents the successive formation of stable cation radical and dication species both in dichloromethane (DCM) and in a CH3CN/THF mixture. In contrast, for compound 5, the stability of the oxidation states strongly depends on the nature of the solvent. In DCM, the oxidation of 5 proceeds by two close one-electron transfers while in CH3CN/THF the dication is directly formed via a two-electron process. The X-ray structures of the two salts reveal the formation of pi-dimers of cation radical. While the dimer (5(2))2+ is due mainly to π–π interactions between the conjugating spacer, the multiplication of the sulfur atoms in compound 4 contributes to stabilize the dimer by the combined effects of S–S and π–π interactions. Visible/NIR and ESR experiments confirm the higher tendency of 4+· to dimerize with the occurrence of dimer and monomer in solution, while for 5+· only the monomer is detected in DCM. On the other hand, by dissolution of 5·BF4(CH2Cl2) in CH3CN, only the neutral and the dicationic states of compounds 5 are observed owing to the disproportionation reaction
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