1,623 research outputs found

    Dynamic and thermal analysis of high speed tapered roller bearings under combined loading

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    The development of a computer program capable of predicting the thermal and kinetic performance of high-speed tapered roller bearings operating with fluid lubrication under applied axial, radial and moment loading (five degrees of freedom) is detailed. Various methods of applying lubrication can be considered as well as changes in bearing internal geometry which occur as the bearing is brought to operating speeds, loads and temperatures

    Testing the proposed link between cosmic rays and cloud cover

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    A decrease in the globally averaged low level cloud cover, deduced from the ISCCP infra red data, as the cosmic ray intensity decreased during the solar cycle 22 was observed by two groups. The groups went on to hypothesise that the decrease in ionization due to cosmic rays causes the decrease in cloud cover, thereby explaining a large part of the presently observed global warming. We have examined this hypothesis to look for evidence to corroborate it. None has been found and so our conclusions are to doubt it. From the absence of corroborative evidence, we estimate that less than 23%, at the 95% confidence level, of the 11-year cycle change in the globally averaged cloud cover observed in solar cycle 22 is due to the change in the rate of ionization from the solar modulation of cosmic rays

    Erioflorin stabilizes the tumor suppressor Pdcd4 by inhibiting its interaction with the E3-ligase ÎČ-TrCP1

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    Loss of the tumor suppressor Pdcd4 was reported for various tumor entities and proposed as a prognostic marker in tumorigenesis. We previously characterized decreased Pdcd4 protein stability in response to mitogenic stimuli, which resulted from p70S6K1-dependent protein phosphorylation, ÎČ-TrCP1-mediated ubiquitination, and proteasomal destruction. Following high-throughput screening of natural product extract libraries using a luciferase-based reporter assay to monitor phosphorylation-dependent proteasomal degradation of the tumor suppressor Pdcd4, we succeeded in showing that a crude extract from Eriophyllum lanatum stabilized Pdcd4 from TPA-induced degradation. Erioflorin was identified as the active component and inhibited not only degradation of the Pdcd4-luciferase-based reporter but also of endogenous Pdcd4 at low micromolar concentrations. Mechanistically, erioflorin interfered with the interaction between the E3-ubiquitin ligase ÎČ-TrCP1 and Pdcd4 in cell culture and in in vitro binding assays, consequently decreasing ubiquitination and degradation of Pdcd4. Interestingly, while erioflorin stabilized additional ÎČ-TrCP-targets (such as IÎșBα and ÎČ-catenin), it did not prevent the degradation of targets of other E3-ubiquitin ligases such as p21 (a Skp2-target) and HIF-1α (a pVHL-target), implying selectivity for ÎČ-TrCP. Moreover, erioflorin inhibited the tumor-associated activity of known Pdcd4- and IÎșBα-regulated αtranscription factors, that is, AP-1 and NF-ÎșB, altered cell cycle progression and suppressed proliferation of various cancer cell lines. Our studies succeeded in identifying erioflorin as a novel Pdcd4 stabilizer that inhibits the interaction of Pdcd4 with the E3-ubiquitin ligase ÎČ-TrCP1. Inhibition of E3-ligase/target-protein interactions may offer the possibility to target degradation of specific proteins only as compared to general proteasome inhibition

    KASCADE: Astrophysical results and tests of hadronic interaction models

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    KASCADE is a multi-detector setup to get redundant information on single air shower basis. The information is used to perform multiparameter analyses to solve the threefold problem of the reconstruction of (i)the unknown primary energy, (ii) the primary mass, and (iii) to quantify the characteristics of the hadronic interactions in the air-shower development. In this talk recent results of the KASCADE data analyses are summarized concerning cosmic ray anisotropy studies, determination of flux spectra for different primary mass groups, and approaches to test hadronic interaction models. Neither large scale anisotropies nor point sources were found in the KASCADE data set. The energy spectra of the light element groups result in a knee-like bending and a steepening above the knee. The topology of the individual knee positions shows a dependency on the primary particle. Though no hadronic interaction model is fully able to describe the multi-parameter data of KASCADE consistently, the more recent models or improved versions of older models reproduce the data better than few years ago.Comment: to appear in Nucl. Phys. B (Proc. Suppl.), Proc. of the XIII ISVHECRI, Pylos 2004 - with a better quality of the figure

    Results from the KASCADE, KASCADE-Grande, and LOPES experiments

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    The origin of high-energy cosmic rays in the energy range from 10^14 to 10^18 eV is explored with the KASCADE and KASCADE-Grande experiments. Radio signals from air showers are measured with the LOPES experiment. An overview on results is given.Comment: Talk at The ninth International Conference on Topics in Astroparticle and Underground Physics, TAUP 2005, Zaragoza, September 10-14, 200

    Large scale cosmic-ray anisotropy with KASCADE

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    The results of an analysis of the large scale anisotropy of cosmic rays in the PeV range are presented. The Rayleigh formalism is applied to the right ascension distribution of extensive air showers measured by the KASCADE experiment.The data set contains about 10^8 extensive air showers in the energy range from 0.7 to 6 PeV. No hints for anisotropy are visible in the right ascension distributions in this energy range. This accounts for all showers as well as for subsets containing showers induced by predominantly light respectively heavy primary particles. Upper flux limits for Rayleigh amplitudes are determined to be between 10^-3 at 0.7 PeV and 10^-2 at 6 PeV primary energy.Comment: accepted by The Astrophysical Journa

    KASCADE-Grande Limits on the Isotropic Diffuse Gamma-Ray Flux between 100 TeV and 1 EeV

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    KASCADE and KASCADE-Grande were multi-detector installations to measure individual air showers of cosmic rays at ultra-high energy. Based on data sets measured by KASCADE and KASCADE-Grande, 90% C.L. upper limits to the flux of gamma-rays in the primary cosmic ray flux are determined in an energy range of 1014−1018{10}^{14} - {10}^{18} eV. The analysis is performed by selecting air showers with a low muon content as expected for gamma-ray-induced showers compared to air showers induced by energetic nuclei. The best upper limit of the fraction of gamma-rays to the total cosmic ray flux is obtained at 3.7×10153.7 \times {10}^{15} eV with 1.1×10−51.1 \times {10}^{-5}. Translated to an absolute gamma-ray flux this sets constraints on some fundamental astrophysical models, such as the distance of sources for at least one of the IceCube neutrino excess models.Comment: Published in The Astrophysical Journal, Volume 848, Number 1. Posted on: October 5, 201
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