214 research outputs found
Antibody levels against BK virus and prostate, kidney and bladder cancers in the EPIC-Oxford cohort
In a case–control study nested within the EPIC-Oxford cohort, there were no statistically significant differences in the prevalence or titre of antibodies against BK virus measured in plasma taken prior to diagnosis between cases with cancer of the prostate (n=31), kidney (n=5) or bladder (n=9) and controls (n=45)
Observation of wave turbulence in vibrating plates
The nonlinear interaction of waves in a driven medium may lead to wave
turbulence, a state such that energy is transferred from large to small
lengthscales. Here, wave turbulence is observed in experiments on a vibrating
plate. The frequency power spectra of the normal velocity of the plate may be
rescaled on a single curve, with power-law behaviors that are incompatible with
the weak turbulence theory of D{\"u}ring et al. [Phys. Rev. Lett. 97, 025503
(2006)]. Alternative scenarios are suggested to account for this discrepancy --
in particular the occurrence of wave breaking at high frequencies. Finally, the
statistics of velocity increments do not display an intermittent behavior
Study of the air-formed oxide layer at the copper surface and its impact on the copper corrosion in an aggressive chloride medium
The electrochemical behaviour of pre-oxidized copper surfaces prepared by heating in air at 90°C was studied to evaluate the impact of the air-formed oxide layer at the copper surface on the corrosion in an aggressive chloride medium. In a first part, the evolution of the chemical composition and the structure of the air-formed oxide layer with the heating time were investigated by cyclic voltammetry in an alkaline medium in which the different oxide species can be discriminated, X-ray photoelectrons spectroscopy experiments (XPS) and water contact angle measurements. It was demonstrated that short heating times produce Cu2O-rich films, while CuO-rich films were obtained after long heating-time periods. Furthermore, cyclic voltammetric data strongly support a stratification of the corrosion products in the mature oxide layer. In a second part, the protection efficiency of air-formed films, aged from 1 to 22 days, against the copper corrosion was study using a potentiodynamic technique and the electrochemical impedance spectroscopy (EIS) in an aerated 0.2 M NaCl aqueous electrolyte. Results demonstrate that the chemical composition of the air-formed oxide layer has an important impact in the overall corrosion process. Results are tentatively explained in terms of composition and structure of the oxide layer
A Non-Algebraic Patchwork
Itenberg and Shustin's pseudoholomorphic curve patchworking is in principle
more flexible than Viro's original algebraic one. It was natural to wonder if
the former method allows one to construct non-algebraic objects. In this paper
we construct the first examples of patchworked real pseudoholomorphic curves in
whose position with respect to the pencil of lines cannot be
realised by any homologous real algebraic curve.Comment: 6 pages, 1 figur
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