38,596 research outputs found

    The Attributes of Catholic Medical Education

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    The Blizzard Challenge 2009

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    The Blizzard Challenge 2009 was the fifth annual Blizzard Challenge. As in 2008, UK English and Mandarin Chinese were the chosen languages for the 2009 Challenge. The English corpus was the same one used in 2008. The Mandarin corpus was provided by iFLYTEK. As usual, participants with limited resources or limited experience in these languages had the option of using unaligned labels that were provided for both corpora and for the test sentences. An accent-specific pronunciation dictionary was also available for the English speaker. This year, the tasks were organised in the form of ‘hubs ’ and ‘spokes ’ where each hub task involved building a general-purpose voice and each spoke task involved building a voice for a specific application. A set of test sentences was released to participants, who were given a limited time in which to synthesise them and submit the synthetic speech. An online listening test was conducted to evaluate naturalness, intelligibility, degree of similarity to the original speaker and, for one of the spoke tasks, “appropriateness.

    Complex structures in galaxy cluster fields: implications for gravitational lensing mass models

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    The distribution of mass on galaxy cluster scales is an important test of structure formation scenarios, providing constraints on the nature of dark matter itself. Several techniques have been used to probe the mass distributions of clusters, sometimes yielding results which are discrepant, or at odds with clusters formed in simulations - for example giving NFW concentration parameters much higher than expected in the standard CDM model. In addition, the velocity fields of some well studied galaxy clusters reveal the presence of several structures close to the line-of-sight, often not dynamically bound to the cluster itself. We investigate what impact such neighbouring but unbound massive structures would have on the determination of cluster profiles using weak gravitational lensing. Depending on its concentration and mass ratio to the primary halo, one secondary halo close to the line-of-sight can cause the estimated NFW concentration parameter to be significantly higher than that of the primary halo, and also cause the estimated mass to be biased high. Although it is difficult to envisage how this mechanism alone could yield concentrations as high as reported for some clusters, multiple haloes close to the line-of-sight, such as in the case of Abell 1689, can substantially increase the concentration parameter estimate. Together with the fact that clusters are triaxial, and that including baryonic physics also leads to an increase in the concentration of a dark matter halo, the tension between observations and the standard CDM model is eased. If the alignment with the secondary structure is imprecise, then the estimated concentration parameter can also be even lower than that of the primary halo, reinforcing the importance of identifying structures in cluster fields.Comment: To appear in MNRAS letters, 5 pages, 3 figure

    Automatic continuum analysis of reflectance spectra

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    A continuum algorithm based on a Segmented Upper Hull method (SUH) is described. An upper hull is performed on segments of a spectrum defined by local minima and maxima. The segments making a complete spectrum are then combined. The definition of the upper hull allows the continuum to be both concave and/or convex, adapting to the shape of the spectrum. The method performs multiple passes on a spectrum by segmenting each local maximum to minimum and performing an upper hull. The algorithm naturally adapts to the widths of absorption features, so that all features are found, including the nature of doublets, triplets, etc. The algorithm is also reasonably fast on common minicomputers so that it might be applied to the large data sets from imaging spectrometers

    Causes of spurious features in spectral reflectance data

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    Several techniques are becoming common in the analysis of imaging spectrometer data that can lead to spurious absorption features or to changes in the position, width, and shape of actual absorption features. It is a common practice to calibrate AIS or other imaging spectrometer data by averaging each pixel along the flight line. The average is used to calibrate the spectral data by dividing the spectrum at each pixel by the average. If some pixels in the data set contain an absorption, then the average will also show an absorption. Some AIS data has had problems with wavelength stability from one scan line to the next which can produce spurious features with some analysis methods. If a pixel has a spectrum with an absorption having a different position or width than the spectrum used in a ratio, then the ratio can produce a spurious absorption at a different position and width than the true absorption feature. An average spectrum ratioed to each pixel will produce band shifts, and changes in width or shape. If continuum removal is performed by substraction rather than division, band positions can also be shifted

    Spectral evidence for carbonates on Mars: Hydrous carbonates

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    Although many of the spectral features of the Martian samples studied are not unique mineralogical indicators, much of the current spectral data is consistent with (possibly abundant) hydrous carbonates on the surface of Mars. The absorption features in the measured samples were quite weak compared with those of anhydrous carbonates. The weak features imply that significantly more hydrous carbonates can be incorporated onto the surface before becoming spectrally evident; however, exact limits have yet to be determined. The stability of these materials in the Martian environment is not known, but their formation and occurrence in low temperature terrestrial environments makes them appealing candidates for weathering products on Mars

    Magnetic blackbody shift of hyperfine transitions for atomic clocks

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    We derive an expression for the magnetic blackbody shift of hyperfine transitions such as the cesium primary reference transition which defines the second. The shift is found to be a complicated function of temperature, and has a T^2 dependence only in the high-temperature limit. We also calculate the shift of ground-state p_1/2 hyperfine transitions which have been proposed as new atomic clock transitions. In this case interaction with the p_3/2 fine-structure multiplet may be the dominant effect
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