13,175 research outputs found

    Stability of the Horizontal Curvature of the LHC Cryodipoles During Cold Tests

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    The LHC will be composed of 1232 horizontally curved, 15 meter long, superconducting dipole magnets cooled at 1.9 K. They are supported within their vacuum vessel by three Glass Fiber Reinforced Epoxy (GFRE) support posts. Each cryodipole is individually cold tested at CERN before its installation and interconnection in the LHC 27 km circumference tunnel. As the magnet geometry under cryogenic operation is extremely important for the LHC machine aperture, a new method has been developed at CERN in order to monitor the magnet curvature change between warm and cold states. It enabled us to conclude that there is no permanent horizontal curvature change of the LHC dipole magnet between warm and cold states, although a systematic horizontal transient deformation during cool-down was detected. This deformation generates loads in the dipole supporting system; further investigation permitted us to infer this behavior to the asymmetric thermal contraction of the rigid magnet thermal shield during cool-down. Controlling the helium flow rate in the thermal shield of the cryomagnet enabled us to reduce the maximal deformation by a factor of approximately two, thus increasing significantly the mechanical safety margin of the supporting system during the CERN cold tests

    Electrical compatibility of transmission fluids in electric vehicles

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    The in electrical vehicles, where the electric motor is inside the transmissielectrical compatibility of the automatic transmission fluids (ATFs) is very important on and in contact with the ATF. This work studies the influence of factors like temperature, time, and air exposition on the oxidation of three ATFs and their changes in electrical conductivity. The results showed that the higher content of additive the lower variations of electrical conductivity with the oxidation; the measurements of electrical conductivity are better than FT-IR ones for monitoring oil thermo-oxidative degradation at initial periods; the conventional ATFs could maintain good electrical compatibility in electrified drivelines, although their materials compatibility and copper corrosion protection of electrical components should be also tested

    Identification of candidate host serum and saliva biomarkers for a better diagnosis of active and latent tuberculosis infection

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    In our work, we aim to identify new candidate host biomarkers to discriminate between active TB patients (n = 28), latent infection (LTBI; n = 27) and uninfected (NoTBI; n = 42) individuals. For that, active TB patients and their contacts were recruited that donated serum and saliva samples. A multiplex assay was performed to study the concentration of different cytokines, chemokines and growth factors. Proteins with significant differences between groups were selected and logistic regression and the area under the ROC curve (AUC) was used to assess the diagnostic accuracy. The best marker combinations that discriminate active TB from NoTBI contacts were [IP-10 + IL-7] in serum and [Fractalkine + IP-10 + IL-1alpha + VEGF] in saliva. Best discrimination between active TB and LTBI was achieved using [IP-10 + BCA-1] in serum (AUC = 0.83) and IP-10 in saliva (p = 0.0007; AUC = 0.78). The levels of TNFalpha (p = 0.003; AUC = 0.73) in serum and the combination of [Fractalkine+IL-12p40] (AUC = 0.83) in saliva, were able to differentiate between NoTBI and LTBI contacts. In conclusion, different individual and combined protein markers could help to discriminate between active TB and both uninfected and latently-infected contacts. The most promising ones include [IP-10 + IL-7], [IP-10 + BCA-1] and TNFalpha in serum and [Fractalkine + IP-10 + IL-1alpha + VEGF], IP-10 and [Fractalkine+IL-12p40] in saliva

    Direct formulation of the supersonic acoustic intensity in space domain

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    International audienceThis paper proposes and examines a direct formulation in space domain of the so-called supersonic acoustic intensity. This quantity differs from the usual (active) intensity by excluding the circulating energy in the near-field of the source, providing a map of the acoustic energy that is radiated into the far field. To date, its calculation has been formulated in the wave number domain, filtering out the evanescent waves outside the radiation circle and reconstructing the acoustic field with only the propagating waves. In this study, the supersonic intensity is calculated directly in space domain by means of a two-dimensional convolution between the acoustic field and a spatial filter mask that corresponds to the space domain representation of the radiation circle. Therefore, the acoustic field that propagates effectively to the far field is calculated via direct filtering in space domain. This paper presents the theory, as well as a numerical example to illustrate some fundamental principles. An experimental study on planar radiators was conducted to verify the validity of the technique. The experimental results are presented, and serve to illustrate the usefulness of the analysis, its strengths and limitations

    Resolving galaxies in time and space: II: Uncertainties in the spectral synthesis of datacubes

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    In a companion paper we have presented many products derived from the application of the spectral synthesis code STARLIGHT to datacubes from the CALIFA survey, including 2D maps of stellar population properties and 1D averages in the temporal and spatial dimensions. Here we evaluate the uncertainties in these products. Uncertainties due to noise and spectral shape calibration errors and to the synthesis method are investigated by means of a suite of simulations based on 1638 CALIFA spectra for NGC 2916, with perturbations amplitudes gauged in terms of the expected errors. A separate study was conducted to assess uncertainties related to the choice of evolutionary synthesis models. We compare results obtained with the Bruzual & Charlot models, a preliminary update of them, and a combination of spectra derived from the Granada and MILES models. About 100k CALIFA spectra are used in this comparison. Noise and shape-related errors at the level expected for CALIFA propagate to 0.10-0.15 dex uncertainties in stellar masses, mean ages and metallicities. Uncertainties in A_V increase from 0.06 mag in the case of random noise to 0.16 mag for shape errors. Higher order products such as SFHs are more uncertain, but still relatively stable. Due to the large number statistics of datacubes, spatial averaging reduces uncertainties while preserving information on the history and structure of stellar populations. Radial profiles of global properties, as well as SFHs averaged over different regions are much more stable than for individual spaxels. Uncertainties related to the choice of base models are larger than those associated with data and method. Differences in mean age, mass and metallicity are ~ 0.15 to 0.25 dex, and 0.1 mag in A_V. Spectral residuals are ~ 1% on average, but with systematic features of up to 4%. The origin of these features is discussed. (Abridged)Comment: A&A, accepte

    A Uniform Analysis of the Ly-alpha forest at z = 0 - 5: II. Measuring the mean intensity of the extragalactic ionizing background using the proximity effect

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    A homogeneous sample of 99 moderate resolution QSO spectra at z > 1.7 were presented in Paper I, including 39 previously unpublished spectra from the Multiple Mirror Telescope. The statistics of the Lyman alpha forest were discussed. In this analysis, we demonstrate that a proximity effect is present in the data, ie. there exists a significant (5.5σ\sigma) deficit of lines at zabs≈zemz_{abs} \approx z_{em}. Within 1.5 h−1h^{-1} Mpc of the QSO emission redshift, the significance does depend on QSO luminosity, in accordance with the theory that this effect is caused by enhanced ionization of hydrogen in the vicinity of the QSO from UV photons from the QSO itself. The photoionization model of Bajtlik, Duncan, and Ostriker (1988) permits an estimate of the mean intensity of the extragalactic background radiation at the Lyman limit. We compare the results of this standard analysis with those obtained using a maximum likelihood technique. The best fit value for J(ν0)J(\nu_{0}) is 7.0−4.4+3.4^{+3.4}_{-4.4} x 10−22^{-22} ergs/s/cm2^{2}/Hz/sr, over the redshift range 1.7 < z < 3.8, using QSO redshifts based on narrow emission lines. The best fit value for the HI ionization rate is 1.9−1.0+1.2^{+1.2}_{-1.0} x 10−12^{-12} s−1^{-1}, in good agreement with models of the background which incorporate QSOs only. This large absorption line sample and these techniques for measuring the background and understanding the systematics involved allow us to place what we believe are are the firmest limits on the background at these redshifts.Comment: revised figures 13 and 14, and other minor corrections, 42 Latex pages, 23 encapsulated Postscript figures, uses emulateapj.sty, To appear in the Sept. 2000 ApJ

    Sperm Hyperactivation and Capacitation Induced By Light Stimuli in Cryopreserved Semen

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    In mammals, such as rabbits, there are some factors involved in possible fertilization, from complex changes in the membrane of the sperm to obstruction or non-existent of vas deferens, which creates problems in the number and quality of sperm. In this work, we report the effects of rabbit sperm motility and capacitation of cryopreserved semen samples under light stimuli. The sperm velocities were correlated with the percentage of capacitated and non-capacitated sperm seen with a fluorescent dye. Consequently, we analyzed the specific correlations between irradiation times, supplied energy, and fertility parameters. KEYWORDS THAT SEARCHED RELATED TO THE ARTICLE ON THE WEB sperm meaning, capacitation, human sperm, capacitation occurs in, what is sperm, capacitation of sperm, sperm lifetime, fertilization definition, fertilization meaning, capacitation meaning, mechanism of fertilization,sperm capacitation, capacitate meaning, fertilization takes place in, capacitate, capacitation of sperm occurs in, capacitation of sperms, capacitated, definition of fertilizatio
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