463 research outputs found

    CMB Polarization Data and Galactic Foregrounds: Estimation of Cosmological Parameters

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    We estimate the accuracy with which various cosmological parameters can be determined from the CMB temperature and polarization data when various galactic unpolarized and polarized foregrounds are included and marginalized using the multi-frequency Wiener filtering technique. We use the specifications of the future CMB missions MAP and PLANCK for our study. Our results are in qualitative agreement with earlier results obtained without foregrounds, though the errors in most parameters are higher because of degradation of the extraction of polarization signal in the presence of foregrounds.Comment: 6 pages, submitted to MNRA

    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 beam1^{-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

    Characterization of Botrytis cinerea populations associated with treated and untreated cv. Moscato vineyards

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    Three Botrytis cinerea populations, isolated from three vineyards, one untreated and two treated twice a year, respectively, with fenhexamid or cyprodinil+fludioxonil, were investigated to evaluate the effect of repeated fungicide treatments on the presence and distribution of the transposons Boty and Flipper, and on the phenotypic traits of each pathogen community. The vacuma individuals lacking the two transposons represented the majority of the 390 B. cinerea isolates followed by transposa strains containing Boty and Flipper, while the remaining 67 isolates harboured respectively only Boty (60) or Flipper (7). This research has demonstrated that fungicide application did not influence the transposon distribution patterns, the sensitivity towards various botryticides, or the growth rate of the isolates belonging to the three different populations, but did induced overall reduction of the population size and selected isolates characterized by an enhanced pathogenicity, especially on Vitis vinifera leaves

    NoPv1: a synthetic antimicrobial peptide aptamer targeting the causal agents of grapevine downy mildew and potato late blight

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    Grapevine (Vitis vinifera L.) is a crop of major economic importance. However, grapevine yield is guaranteed by the massive use of pesticides to counteract pathogen infections. Under temperate- humid climate conditions, downy mildew is a primary threat for viticulture. Downy mildew is caused by the biotrophic oomycete Plasmopara viticola Berl. & de Toni, which can attack grapevine green tissues. In lack of treatments and with favourable weather conditions, downy mildew can devastate up to 75% of grape cultivation in one season and weaken newly born shoots, causing serious economic losses. Nevertheless, the repeated and massive use of some fungicides can lead to environmental pollution, negative impact on non-targeted organisms, development of resistance, residual toxicity and can foster human health concerns. In this manuscript, we provide an innovative approach to obtain specific pathogen protection for plants. By using the yeast two-hybrid approach and the P. viticola cellulose synthase 2 (PvCesA2), as target enzyme, we screened a combinatorial 8 amino acid peptide library with the aim to identify interacting peptides, potentially able to inhibit PvCesa2. Here, we demonstrate that the NoPv1 peptide aptamer prevents P. viticola germ tube formation and grapevine leaf infection without affecting the growth of non-target organisms and without being toxic for human cells. Furthermore, NoPv1 is also able to counteract Phytophthora infestans growth, the causal agent of late blight in potato and tomato, possibly as a consequence of the high amino acid sequence similarity between P. viticola and P. infestans cellulose synthase enzymes

    Cosmic Complementarity: Joint Parameter Estimation from CMB Experiments and Redshift Surveys

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    We study the ability of future CMB anisotropy experiments and redshift surveys to constrain a thirteen-dimensional parameterization of the adiabatic cold dark matter model. Each alone is unable to determine all parameters to high accuracy. However, considered together, one data set resolves the difficulties of the other, allowing certain degenerate parameters to be determined with far greater precision. We treat in detail the degeneracies involving the classical cosmological parameters, massive neutrinos, tensor-scalar ratio, bias, and reionization optical depth as well as how redshift surveys can resolve them. We discuss the opportunities for internal and external consistency checks on these measurements. Previous papers on parameter estimation have generally treated smaller parameter spaces; in direct comparisons to these works, we tend to find weaker constraints and suggest numerical explanations for the discrepancies.Comment: Submitted to ApJ. LaTeX, 20 pages, emulateapj.sty and onecolfloat.sty. Minor errors in Table 8 corrected; reference adde

    A 20 GHz bright sample for {\delta} > +72{\deg}: I. Catalogue

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    During 2010-2011, the Medicina 32-m dish hosted the 7-feed 18-26.5 GHz receiver built for the Sardinia Radio Telescope, with the goal to perform its commissioning. This opportunity was exploited to carry out a pilot survey at 20 GHz over the area for {\delta} > + 72.3{\deg}. This paper describes all the phases of the observations, as they were performed using new hardware and software facilities. The map-making and source extraction procedures are illustrated. A customised data reduction tool was used during the follow-up phase, which produced a list of 73 confirmed sources down to a flux density of 115 mJy. The resulting catalogue, here presented, is complete above 200 mJy. Source counts are in agreement with those provided by the AT20G survey. This pilot activity paves the way to a larger project, the K-band Northern Wide Survey (KNoWS), whose final aim is to survey the whole Northern Hemisphere down to a flux limit of 50 mJy (5{\sigma}).Comment: 10 pages, 10 figures. Accepted by MNRA

    The pre-launch Planck Sky Model: a model of sky emission at submillimetre to centimetre wavelengths

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    We present the Planck Sky Model (PSM), a parametric model for the generation of all-sky, few arcminute resolution maps of sky emission at submillimetre to centimetre wavelengths, in both intensity and polarisation. Several options are implemented to model the cosmic microwave background, Galactic diffuse emission (synchrotron, free-free, thermal and spinning dust, CO lines), Galactic H-II regions, extragalactic radio sources, dusty galaxies, and thermal and kinetic Sunyaev-Zeldovich signals from clusters of galaxies. Each component is simulated by means of educated interpolations/extrapolations of data sets available at the time of the launch of the Planck mission, complemented by state-of-the-art models of the emission. Distinctive features of the simulations are: spatially varying spectral properties of synchrotron and dust; different spectral parameters for each point source; modeling of the clustering properties of extragalactic sources and of the power spectrum of fluctuations in the cosmic infrared background. The PSM enables the production of random realizations of the sky emission, constrained to match observational data within their uncertainties, and is implemented in a software package that is regularly updated with incoming information from observations. The model is expected to serve as a useful tool for optimizing planned microwave and sub-millimetre surveys and to test data processing and analysis pipelines. It is, in particular, used for the development and validation of data analysis pipelines within the planck collaboration. A version of the software that can be used for simulating the observations for a variety of experiments is made available on a dedicated website.Comment: 35 pages, 31 figure

    From M-ary Query to Bit Query: a new strategy for efficient large-scale RFID identification

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    The tag collision avoidance has been viewed as one of the most important research problems in RFID communications and bit tracking technology has been widely embedded in query tree (QT) based algorithms to tackle such challenge. Existing solutions show further opportunity to greatly improve the reading performance because collision queries and empty queries are not fully explored. In this paper, a bit query (BQ) strategy based Mary query tree protocol (BQMT) is presented, which can not only eliminate idle queries but also separate collided tags into many small subsets and make full use of the collided bits. To further optimize the reading performance, a modified dual prefixes matching (MDPM) mechanism is presented to allow multiple tags to respond in the same slot and thus significantly reduce the number of queries. Theoretical analysis and simulations are supplemented to validate the effectiveness of the proposed BQMT and MDPM, which outperform the existing QT-based algorithms. Also, the BQMT and MDPM can be combined to BQMDPM to improve the reading performance in system efficiency, total identification time, communication complexity and average energy cost

    Planck intermediate results: XVI. Profile likelihoods for cosmological parameters

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    We explore the 2013 Planck likelihood function with a high-precision multi-dimensional minimizer (Minuit). This allows a refinement of the CDM best-fit solution with respect to previously-released results, and the construction of frequentist confidence intervals using profile likelihoods. The agreement with the cosmological results from the Bayesian framework is excellent, demonstrating the robustness of the Planck results to the statistical methodology. We investigate the inclusion of neutrino masses, where more significant differences may appear due to the non-Gaussian nature of the posterior mass distribution. By applying the Feldman-Cousins prescription, we again obtain results very similar to those of the Bayesian methodology. However, the profile-likelihood analysis of the cosmic microwave background (CMB) combination (Planck+WP+highL) reveals a minimum well within the unphysical negative-mass region. We show that inclusion of the Planck CMB-lensing information regularizes this issue, and provide a robust frequentist upper limit σmv ≤0:26 eV (95% confidence) from the CMB+lensing+BAO data combination. © ESO 2014.The development of Planck has been supported by: ESA; CNES and CNRS/INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA); STFC and UKSA (UK); CSIC, MICINN and JA (Spain); Tekes, AoF and CSC (Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO (Switzerland); RCN (Norway); SFI (Ireland); FCT/MCTES (Portugal); and PRACE (EU).Peer Reviewe
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