438 research outputs found

    Influences of Propagation Method, Rootstock, Number of Axes, and Cultivation Site on ‘Fuji’ Scions Grown as Single or Multi-Leader Trees in the Nursery

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    The adoption of high-density plantings (HDP) in apple orchards started with the introduction of dwarfing rootstocks from East Malling’s (UK) breeding program. A range of spindle-derived training systems have been developed to improve light interception/distribution with a variation in leader numbers. Many of these training systems cannot guarantee early, consistent, and uniform illumination of the entire canopy. For this reason, planar 2-D canopies have been developed with varying numbers of primary axes with numerous second-order shoots. In this trial, carried out at the nursery level, three sites were selected: one in New Zealand (Hawke’s Bay Research Centre) and two in Italy (Bologna and Trento). Trees were produced with a single-, bi-, and tri-axis system utilizing three rootstocks (‘M27’, ‘M9’, ‘MM106’), characterized by an increasing level of vigor. The cultivation site played an important role in modulating early tree performance. Multi-leader trees reduced average shoot length in the Italian sites in the first year after grafting. The number of shoots and total growth developed on multi-leader trees was higher than single-axis trees. This may benefit growers that seek to use canopy architecture manipulation to fill space and control vigor when establishing HDP orchards

    K-band luminosity (mass) segregation in AC118 at z=0.31

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    Using new observations of the galaxy cluster A118 at intermediate redshift (z=0.31) in the Ks band, we were able to detect the cluster from the center to half the Abell radius (1.5 Mpc, Ho=50 km/s/Mpc) and possibly to 2.0 Mpc. The analysis of both the spatial distribution of galaxies of various luminosities and of the luminosity function (LF) of galaxies in different cluster locations strongly confirms and extends to larger clustercentric radii the luminosity segregation found in a previous analysis of this cluster restricted to a smaller cluster area: there is an excess of bright galaxies in the cluster core (inside 250 Kpc) or a deficit of dwarfs in the remain part of the cluster. Outside the cluster core and as far as 1.5 or even 2 Mpc, the giant-to-dwarf ratio is constant. Because of the luminosity segregation, the LF of the AC118 shows a larger number of bright galaxies per unit dwarf in the core than in other cluster locations. All non-core LFs, computed at several cluster locations, are compatible each other. These results hold both including or excluding the galaxies located in an overdensity found in the far South of AC118 and in the second clump in galaxy density at the cluster North-West. Since the near-infrared emission is a good tracer of the stellar mass, we interpret the segregation found as a mass segregation.Comment: A&A in pres

    Use of Individual-Level Covariates to Improve Latent Class Analysis of Trypanosoma Cruzi Diagnostic Tests

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    Statistical methods such as latent class analysis can estimate the sensitivity and specificity of diagnostic tests when no perfect reference test exists. Traditional latent class methods assume a constant disease prevalence in one or more tested populations. When the risk of disease varies in a known way, these models fail to take advantage of additional information that can be obtained by measuring risk factors at the level of the individual. We show that by incorporating complex field-based epidemiologic data, in which the disease prevalence varies as a continuous function of individual-level covariates, our model produces more accurate sensitivity and specificity estimates than previous methods. We apply this technique to several simulated populations and to actual Chagas disease test data from a community near Arequipa, Peru. Results from our model estimate that the first-line enzyme-linked immunosorbent assay has a sensitivity of 78% (95% CI: 62-100%) and a specificity of 100% (95% CI: 99-100%). The confirmatory immunofluorescence assay is estimated to be 73% sensitive (95% CI: 65-81%) and 99% specific (95% CI: 96-100%)

    Theory and practice: bulk synthesis of C3B and its H2- and Li-storage capacity.

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    Previous theoretical studies of C3B have suggested that boron-doped graphite is a promising H2- and Li-storage material, with large maximum capacities. These characteristics could lead to exciting applications as a lightweight H2-storage material for automotive engines and as an anode in a new generation of batteries. However, for these applications to be realized a synthetic route to bulk C3B must be developed. Here we show the thermolysis of a single-source precursor (1,3-(BBr2)2C6H4) to produce graphitic C3B, thus allowing the characteristics of this elusive material to be tested for the first time. C3B was found to be compositionally uniform but turbostratically disordered. Contrary to theoretical expectations, the H2- and Li-storage capacities are lower than anticipated, results that can partially be explained by the disordered nature of the material. This work suggests that to model the properties of graphitic materials more realistically, the possibility of disorder must be considered.We thank the ERC (Advance Investigator awards for D.S.W., C.P.G.), the EPSRC (T.C.K., P.D.M., H.G., J.C.), and the Spanish Ministerio de Economia y Competitividad (under grants ENE2011-24-412 and IPT-2011-1553-420000). We thank John Bulmer for Raman spectroscopy and Keith Parmenter for glass blowing. We thank the Schlumberger Gould Research Centre for XPS analysis.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/anie.20141220

    Pandemic H1N1 in Canada and the use of evidence in developing public health policies e A policy analysis

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    a b s t r a c t When responding to a novel infectious disease outbreak, policies are set under time constraints and uncertainty which can limit the ability to control the outbreak and result in unintended consequences including lack of public confidence. The H1N1 pandemic highlighted challenges in public health decision-making during a public health emergency. Understanding this process to identify barriers and modifiable influences is important to improve the response to future emergencies. The purpose of this study is to examine the H1N1 pandemic decision-making process in Canada with an emphasis on the use of evidence for public health decisions. Using semi-structured key informant interviews conducted after the pandemic (JulyeNovember 2010) and a document analysis, we examined four highly debated pandemic policies: use of adjuvanted vaccine by pregnant women, vaccine priority groups and sequencing, school closures and personal protective equipment. Data were analysed for thematic content guided by Lomas' policy decision-making framework as well as indicative coding using iterative methods. We interviewed 40 public health officials and scientific advisors across Canada and reviewed 76 pandemic policy documents. Our analysis revealed that pandemic pre-planning resulted in strong beliefs, which defined the decision-making process. Existing ideological perspectives of evidence strongly influenced how information was used such that the same evidentiary sources were interpreted differently according to the ideological perspective. Participants recognized that current models for public health decision-making failed to make explicit the roles of scientific evidence in relation to contextual factors. Conflict avoidance theory explained policy decisions that went against the prevailing evidence. Clarification of roles and responsibilities within the public health system would reduce duplication and maintain credibility. A more transparent and iterative approach to incorporating evidence into public health decision-making that reflects the realities of the external pressures present during a public health emergency is needed

    A High Fidelity Sample of Cold Front Clusters from the Chandra Archive

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    This paper presents a sample of "cold front" clusters selected from the Chandra archive. The clusters are selected based purely on the existence of surface brightness edges in their Chandra images which are modeled as density jumps. A combination of the derived density and temperature jumps across the fronts is used to select nine robust examples of cold front clusters: 1ES0657-558, Abell 1201, Abell 1758N, MS1455.0+2232, Abell 2069, Abell 2142, Abell 2163, RXJ1720.1+2638, and Abell 3667. This sample is the subject of an ongoing study aimed at relating cold fronts to cluster merger activity, and understanding how the merging environment affects the cluster constituents. Here, temperature maps are presented along with the Chandra X-ray images. A dichotomy is found in the sample in that there exists a subsample of cold front clusters which are clearly mergers based on their X-ray morphologies, and a second subsample which harbor cold fronts, but have surprisingly relaxed X-ray morphologies, and minimal evidence for merger activity at other wavelengths. For this second subsample, the existence of a cold front provides the sole evidence for merger activity at X-ray wavelengths. We discuss how cold fronts can provide additional information which may be used to constrain merger histories, and also the possibility of using cold fronts to distinguish major and minor mergers.Comment: 25 pages, 10 figures. Accepted for publication in ApJ. A high resolution version is available for download at: http://www.astronomy.swin.edu.au/~mowers/cold_front_paper.ps.g
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