909 research outputs found

    Herschel-ATLAS: Blazars in the science demonstration phase field

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    To investigate the poorly constrained sub-mm counts and spectral properties of blazars we searched for these in the Herschel-ATLAS (H-ATLAS) science demonstration phase (SDP) survey catalog.

We cross-matched 500 μm sources brighter than 50 mJy with the FIRST radio catalogue. We found two blazars, both previously known. Our study is among the first blind blazar searches at sub-mm wavelengths, i.e., in the spectral regime where little is still known about the blazar SEDs, but where the synchrotron peak of the most luminous blazars is expected to occur. Our early results are consistent with educated extrapolations of lower frequency counts and question indications of substantial spectral curvature downwards and of spectral upturns at mm wavelengths. One of the two blazars is identified with a Fermi/LAT γ-ray source and a WMAP source. The physical parameters of the two blazars are briefly discussed. These observations demonstrate that the H-ATLAS survey will provide key information about the physics of blazars and their contribution to sub-mm counts

    Statistics of the fractional polarisation of compact radio sources in Planck maps

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    In this work we apply the stacking technique to estimate the average fractional polarisation from 30 to 353 GHz of a primary sample of 1560 compact sources - essentially all radio sources - detected in the 30 GHz Planck all-sky map and listed in the second version of the Planck Catalogue of Compact Sources (PCCS2). We divide our primary sample in two subsamples according to whether the sources lay (679 sources) or not (881 sources) inside the sky region defined by the Planck Galactic mask (fsky ~ 60 per cent) and the area around the Magellanic Clouds. We find that the average fractional polarisation of compact sources is approximately constant (with frequency) in both samples (with a weighted mean over all the channels of 3.08 per cent outside and 3.54 per cent inside the Planck mask). In the sky region outside the adopted mask, we also estimate the {\mu} and {\sigma} parameters for the log-normal distribution of the fractional polarisation, finding a weighted mean value over all the Planck frequency range of 1.0 for {\sigma} and 0.7 for {\mu} (that would imply a weighted mean value for the median fractional polarisation of 1.9 per cent).Comment: 12 pages, 7 figures, 2 tables, MNRAS in pres

    Real-time Quantum evolution in the Classical approximation and beyond

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    With the goal in mind of deriving a method to compute quantum corrections for the real-time evolution in quantum field theory, we analyze the problem from the perspective of the Wigner function. We argue that this provides the most natural way to justify and extend the classical approximation. A simple proposal is presented that can allow to give systematic quantum corrections to the evolution of expectation values and/or an estimate of the errors committed when using the classical approximation. The method is applied to the case of a few degrees of freedom and compared with other methods and with the exact quantum results. An analysis of the dependence of the numerical effort involved as a function of the number of variables is given, which allow us to be optimistic about its applicability in a quantum field theoretical context.Comment: 32 pages, 6 figure

    Intrusions of warm and salty waters onto the NW and N Iberian shelf in early spring and its relationship to climate variability

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    Temperature and salinity data from a series of cruises carried out on the NW and N Iberian shelf, between 1987 and 2005 during early spring, were analysed to investigate the inter-annual variability of the intrusions of warm and salty waters into the Cantabrian Sea, and its relationship with the meridional sea surface temperature (SST) gradient in the NE Atlantic and the main modes of climate variability affecting the Northern Hemisphere. A sub-surface front, that separates warmer and saltier (i.e. spicy) waters in the westernmost part of the Iberian shelf from the colder and fresher waters, characteristic of the easternmost part of the southern Bay of Biscay, was observed in all the analysed years. The location of this sub-surface front, which defines the limit of the influence of the Subtropical mode of Eastern North Atlantic Central Water (ENACWst) advected by the Iberian Poleward Current (IPC), varied approximately between Finisterre Cape (43ºN, 9ºW) and Penñas Cape (43.5ºN, 6ºW), being located on average around the Ortegal Cape (43.5ºN, 8ºW). Its position, alongshore the Southern Bay of Biscay shelf, is displaced westward as the spring season progresses, and showed a positive correlation with the summer–autumn (July–October, JASO) meridional SST gradient (measured between 36º N 15º W and 46º N 15º W) of the previous year. This gradient was in turn correlated with the values of the Eastern Atlantic (EA) climate index for the same period.FICY

    Overexpression of mitochondrial if1 prevents metastatic disease of colorectal cancer by enhancing anoikis and tumor infiltration of NK cells

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    Increasing evidences show that the ATPase Inhibitory Factor 1 (IF1), the physiological inhibitor of the ATP synthase, is overexpressed in a large number of carcinomas contributing to metabolic reprogramming and cancer progression. Herein, we show that in contrast to the findings in other carcinomas, the overexpression of IF1 in a cohort of colorectal carcinomas (CRC) predicts less chances of disease recurrence, IF1 being an independent predictor of survival. Bioinformatic and gene expression analyses of the transcriptome of colon cancer cells with differential expression of IF1 indicate that cells overexpressing IF1 display a less aggressive behavior than IF1 silenced (shIF1) cells. Proteomic and functional in vitro migration and invasion assays confirmed the higher tumorigenic potential of shIF1 cells. Moreover, shIF1 cells have increased in vivo metastatic potential. The higher metastatic potential of shIF1 cells relies on increased cFLIP-mediated resistance to undergo anoikis after cell detachment. Furthermore, tumor spheroids of shIF1 cells have an increased ability to escape from immune surveillance by NK cells. Altogether, the results reveal that the overexpression of IF1 acts as a tumor suppressor in CRC with an important anti-metastatic role, thus supporting IF1 as a potential therapeutic target in CRCThis research was funded by grants from Ministerio de Ciencia, Innovación y Universidades (SAF2013-41945-R, SAF2016-75916-R and SAF2016-75452-R), CIBERER-ISCIII (CB06/07/0017) and Fundación Ramón Areces, Spai

    A multifrequency method based on the Matched Multifilter for the detection of point sources in CMB maps

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    In this work we deal with the problem of simultaneous multifrequency detection of extragalactic point sources in maps of the Cosmic Microwave Background. We apply a linear filtering technique that uses spatial information and the cross-power spectrum. To make this, we simulate realistic and non-realistic flat patches of the sky at two frequencies of Planck: 44 and 100 GHz. We filter to detect and estimate the point sources and compare this technique with the monofrequency matched filter in terms of completeness, reliability, flux and spectral index accuracy. The multifrequency method outperforms the matched filter at the two frequencies and in all the studied cases in the work.Comment: 14 pages, 6 figures, 1 tabl

    Simplifying quality control and standardization of CTD data under SeaDataNet requirements

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    Sharing marine data through SeaDataNet infrastructure ensures preservation and promotes reusability. Submission of data to this infrastructure demands a set of technical tasks that cover quality control processing, adoption of common vocabularies, implement fle format standards and preparation of associated metadata. Although common software tools are made available to Data Centres and/or End Users to facilitate data and metadata preparation, these tasks continuous to be complex and time-consuming. To speed-up this process, a Python-Flask web application is presented here to quality check and create metadata and data according to SeaDataNet requirements. The web tool focuses on CTD vertical profles, although code could be easily adapted to process other type of records.Peer Reviewe
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