51,085 research outputs found

    Multidimensional Scaling with Regional Restrictions for Facet Theory: An Application to Levi's Political Protest Data

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    Multidimensional scaling (MDS) is often used for the analysis of correlation matrices of items generated by a facet theory design. The emphasis of the analysis is on regional hypotheses on the location of the items in the MDS solution. An important regional hypothesis is the axial constraint where the items from different levels of a facet are assumed to be located in different parallel slices. The simplest approach is to do an MDS and draw the parallel lines separating the slices as good as possible by hand. Alternatively, Borg and Shye (1995) propose to automate the second step. Borg and Groenen (1997, 2005) proposed a simultaneous approach for ordered facets when the number of MDS dimensions equals the number of facets. In this paper, we propose a new algorithm that estimates an MDS solution subject to axial constraints without the restriction that the number of facets equals the number of dimensions. The algorithm is based on constrained iterative majorization of De Leeuw and Heiser (1980) with special constraints. This algorithm is applied to Levi’s (1983) data on political protests.Axial Partitioning;Constrained Estimation;Facet Theory;Iterative Majorization;Multidimensional Scaling;Regional Restrictions

    Borg’s Minimalism and the Problem of Paradox

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    According to Emma Borg, minimalism is (roughly) the view that natural language sentences have truth conditions, and that these truth conditions are fully determined by syntactic structure and lexical content. A principal motivation for her brand of minimalism is that it coheres well with the popular view that semantic competence is underpinned by the cognition of a minimal semantic theory. In this paper, I argue that the liar paradox presents a serious problem for this principal motivation. Two lines of response to the problem are discussed, and difficulties facing those responses are raised. I close by issuing a challenge: to construe the principal motivation for Borg’s version of minimalism in such a way so as to avoid the problem of paradox

    A spectroscopically confirmed z=1.327 galaxy-scale deflector magnifying a z~8 Lyman-Break galaxy in the Brightest of Reionizing Galaxies survey

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    We present a detailed analysis of an individual case of gravitational lensing of a z∼8z\sim8 Lyman-Break galaxy (LBG) in a blank field, identified in Hubble Space Telescope imaging obtained as part of the Brightest of Reionizing Galaxies survey. To investigate the close proximity of the bright (mAB=25.8m_{AB}=25.8) Y098Y_{098}-dropout to a small group of foreground galaxies, we obtained deep spectroscopy of the dropout and two foreground galaxies using VLT/X-Shooter. We detect H-α\alpha, H-β\beta, [OIII] and [OII] emission in the brightest two foreground galaxies (unresolved at the natural seeing of 0.80.8 arcsec), placing the pair at z=1.327z=1.327. We can rule out emission lines contributing all of the observed broadband flux in H160H_{160} band at 70σ70\sigma, allowing us to exclude the z∼8z\sim8 candidate as a low redshift interloper with broadband photometry dominated by strong emission lines. The foreground galaxy pair lies at the peak of the luminosity, redshift and separation distributions for deflectors of strongly lensed z∼8z\sim8 objects, and we make a marginal detection of a demagnified secondary image in the deepest (J125J_{125}) filter. We show that the configuration can be accurately modelled by a singular isothermal ellipsoidal deflector and a S\'{e}rsic source magnified by a factor of μ=4.3±0.2\mu=4.3\pm0.2. The reconstructed source in the best-fitting model is consistent with luminosities and morphologies of z∼8z\sim8 LBGs in the literature. The lens model yields a group mass of 9.62±0.31×1011M⊙9.62\pm0.31\times10^{11} M_{\odot} and a stellar mass-to-light ratio for the brightest deflector galaxy of M⋆/LB=2.3−0.6+0.8M⊙/L⊙M_{\star}/L_{B}=2.3^{+0.8}_{-0.6} M_{\odot}/L_{\odot} within its effective radius. The foreground galaxies' redshifts would make this one of the few strong lensing deflectors discovered at z>1z>1.Comment: Accepted for publication in MNRAS. 16 pages, 11 figures, 3 table
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