10,871 research outputs found

    Comment on ``Two Time Scales and Violation of the Fluctuation-Dissipation Theorem in a Finite Dimensional Model for Structural Glasses''

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    In cond-mat/0002074 Ricci-Tersenghi et al. find two linear regimes in the fluctuation-dissipation relation between density-density correlations and associated responses of the Frustrated Ising Lattice Gas. Here we show that this result does not seem to correspond to the equilibrium quantities of the model, by measuring the overlap distribution P(q) of the density and comparing the FDR expected on the ground of the P(q) with the one measured in the off-equilibrium experiments.Comment: RevTeX, 1 page, 2 eps figures, Comment on F. Ricci-Tersenghi et al., Phys. Rev. Lett. 84, 4473 (2000

    PCA Tomography and its application to nearby galactic nuclei

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    With the development of modern technologies such as IFUs, it is possible to obtain data cubes in which one produces images with spectral resolution. To extract information from them can be quite complex, and hence the development of new methods of data analysis is desirable. We briefly describe a method of analysis of data cubes (data from single field observations, containing two spatial and one spectral dimension) that uses Principal Component Analysis (PCA) to express the data in the form of reduced dimensionality, facilitating efficient information extraction from very large data sets. We applied the method, for illustration purpose, to the central region of the low ionization nuclear emission region (LINER) galaxy NGC 4736, and demonstrate that it has a type 1 active nucleus, not known before. Furthermore, we show that it is displaced from the centre of its stellar bulge.Comment: 4 pages, 1 figure, 1 table, to be published in the Proceedings of the IAU Symposium no. 26

    Impairment of the autophagic flux in astrocytes intoxicated by trimethyltin

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    Autophagy is a lysosomal catabolic route for protein aggregates and damaged organelles which in different stress conditions, such as starvation, generally improves cell survival. An impairment of this degradation pathway has been reported to occur in many neurodegenerative processes. Trimethyltin (TMT) is a potent neurotoxin present as an environmental contaminant causing tremors, seizures and learning impairment in intoxicated subjects. The present data show that in rat primary astrocytes autophagic vesicles (AVs) appeared after few hours of TMT treatment. The analysis of the autophagic flux in TMT-treated astrocytes was consistent with a block of the late stages of autophagy and was accompanied by a progressive accumulation of the microtubule associated protein light chain 3 (LC3) and of p62/SQSTM1. Interestingly, an increased immunoreactivity for p62/SQSTM1 was also observed in hippocampal astrocytes detected in brain slices of TMT-intoxicated rats. The time-lapse recordings of AVs in EGFP-mCherry-LC3B transfected astrocytes demonstrated a reduced mobility of autophagosomes after TMT exposure respect to control cells. The observed block of the autophagic flux cannot be overcome by known autophagy inducers such as rapamycin or 0.5mM lithium. Although ineffective when used at 0.5mM, lithium at higher concentrations (2mM) was able to protect astrocyte cultures from TMT toxicity. This effect correlated well with its ability to determine the phosphorylation/inactivation of glycogen kinase synthase-3β (GSK-3β)

    Requirements of the authorized examinator physician (AME) for class II: interpretative doubts and suggestions

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    The purpose of this document is to clarify the requirements that a doctor must have for carrying out the Authorized Examiner (AME) activity for class II workers. We have consulted the normative sources that indicate the requisite that the authorized physicians must possess and subsequently we have compared the norms, the European Union regulations and the national ones issued by the National Civil Aviation Body (ENAC), as well as the guidelines indicated by the EASA. Finally, Authors give suggestions that can be given to ENAC regarding the issue of the authorization as AME examiner for class II workers

    1.4 GHz polarimetric observations of the two fields imaged by the DASI experiment

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    We present results of polarization observations at 1.4 GHz of the two fields imaged by the DASI experiment (α=23h30m\alpha = 23^{\rm h} 30^{\rm m}, δ=−55∘\delta = -55^{\circ} and α=00h30m\alpha = 00^{\rm h} 30^{\rm m}, δ=−55∘\delta = -55^{\circ}, respectively). Data were taken with the Australia Telescope Compact Array with 3.4 arcmin resolution and ∼0.18\sim 0.18 mJy beam−1^{-1} sensitivity. The emission is dominated by point sources and we do not find evidence for diffuse synchrotron radiation even after source subtraction. This allows to estimate an upper limit of the diffuse polarized emission. The extrapolation to 30 GHz suggests that the synchrotron radiation is lower than the polarized signal measured by the DASI experiment by at least 2 orders of magnitude. This further supports the conclusions drawn by the DASI team itself about the negligible Galactic foreground contamination in their data set, improving by a factor ∼5\sim 5 the upper limit estimated by Leitch et al. (2005). The dominant point source emission allows us to estimate the contamination of the CMB by extragalactic foregrounds. We computed the power spectrum of their contribution and its extrapolation to 30 GHz provides a framework where the CMB signal should dominate. However, our results do not match the conclusions of the DASI team about the negligibility of point source contamination, suggesting to take into account a source subtraction from the DASI data.Comment: 7 pages, six figures, submitted to MNRA
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