15,819 research outputs found

    The Use of the Terms Negro and Black to Include Persons of Native American Ancestry in Anglo North America

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    In 1854 the California State Supreme Court sought to bar all non-Caucasians from equal citizenship and civil rights. The court stated: The word Black may include all Negroes, but the term Negro does not include all Black persons . . . . We are of the opinion that the words White, Negro, Mulatto and Black person, whenever they occur in our constitution . . . must be taken in their generic sense . . . that the words Black person, in the 14th section must be taken as contra distinguished from White, and necessarily includes all races other than the Caucasian.[1] As convoluted as the quote may be, it tends to express a strong tendency in the history of the United States, toward creating two broad classes of people: white and non-white, citizen and non-citizen (or semi-citizen)

    Theta Graph Designs

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    We solve the design spectrum problem for all theta graphs with 10, 11, 12, 13, 14 and 15 edges

    Icosahedron designs

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    It is known from the work of Adams and Bryant that icosahedron designs of order v exist for v ≡ 1 (mod 60) as well as for v = 16. Here we prove that icosahedron designs exist if and only if v ≡ 1, 16, 21 or 36 (mod 60), wit

    Fascism: A Review of Its History and Its Present Cultural Reality in the Americas

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    The Italians may have given us the word “fascismo,” but whether we use that word or the Spanish ”falangismo” or the German “National Socialism” (Naziism) we are talking about a form of social organization which has a complex history. Indeed, many persons wrongly believe that fascism as a political system first achieved state power in Italy in the 1920s. However, fascism in modern times first achieved independent (sovereign) power in the Americas -- in the Argentina of Juan Manuel de Rosas (1830s) and in the Confederate States of America (1860-1865)

    The Southern Vilnius Photometric System. IV. The E Regions Standard Stars

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    This paper is the fourth in a series on the extension of the Vilnius photometric system to the southern hemisphere. Observations were made of 60 stars in the Harvard Standard E regions to increase a set of standard stars.Comment: 6 pages, TeX, requires 2 macros (baltic2.tex, baltic4.tex) included no figures, to be published in Baltic Astronomy, Vol 6, pp1-6 (1997

    Formation of the Galactic globular clusters with He-rich stars in low-mass halos virialized at high redshift

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    Recent observations have reported that the Galactic globular clusters (GCs) with unusually extended horizontal-branch (EHB) morphologies show a significantly lower velocity dispersion compared with that of the entire Galactic GC system. We consider that the observed distinctive kinematics of GCs with EHB has valuable information on the formation epochs of GCs and accordingly discuss this observational result based on cosmological N-body simulations with a model of GC formation. We assume that GCs in galaxies were initially formed in low-mass halos at high redshifts and we investigate final kinematics of GCs in their host halos at z=0z=0. We find that GCs formed in halos virialized at z>10 show lower velocity dispersions on average than those formed at z>6 for halos with GCs at z=0. We thus suggest that the origin of the observed lower velocity dispersion for the Galactic GCs with EHBs is closely associated with earlier formation epochs (z>10) of halos initially hosting the GCs in the course of the Galaxy formation. Considering that the origin of EHBs can be due to the presence of helium-enhanced second-generation stars in GCs, we discuss the longstanding second parameter problem of GCs in the context of different degrees of chemical pollution in GC-forming gas clouds within low-mass halos virialized at different redshifts.Comment: 5 pages, 3 figures, accepted by MNRAS Letter

    Approximate Bayesian computation via the energy statistic

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    Approximate Bayesian computation (ABC) has become an essential part of the Bayesian toolbox for addressing problems in which the likelihood is prohibitively expensive or entirely unknown, making it intractable. ABC defines a pseudo-posterior by comparing observed data with simulated data, traditionally based on some summary statistics, the elicitation of which is regarded as a key difficulty. Recently, using data discrepancy measures has been proposed in order to bypass the construction of summary statistics. Here we propose to use the importance-sampling ABC (IS-ABC) algorithm relying on the so-called two-sample energy statistic. We establish a new asymptotic result for the case where both the observed sample size and the simulated data sample size increase to infinity, which highlights to what extent the data discrepancy measure impacts the asymptotic pseudo-posterior. The result holds in the broad setting of IS-ABC methodologies, thus generalizing previous results that have been established only for rejection ABC algorithms. Furthermore, we propose a consistent V-statistic estimator of the energy statistic, under which we show that the large sample result holds, and prove that the rejection ABC algorithm, based on the energy statistic, generates pseudo-posterior distributions that achieves convergence to the correct limits, when implemented with rejection thresholds that converge to zero, in the finite sample setting. Our proposed energy statistic based ABC algorithm is demonstrated on a variety of models, including a Gaussian mixture, a moving-average model of order two, a bivariate beta and a multivariate gg-and-kk distribution. We find that our proposed method compares well with alternative discrepancy measures.Comment: 25 pages, 6 figures, 5 table

    EM Algorithms for Weighted-Data Clustering with Application to Audio-Visual Scene Analysis

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    Data clustering has received a lot of attention and numerous methods, algorithms and software packages are available. Among these techniques, parametric finite-mixture models play a central role due to their interesting mathematical properties and to the existence of maximum-likelihood estimators based on expectation-maximization (EM). In this paper we propose a new mixture model that associates a weight with each observed point. We introduce the weighted-data Gaussian mixture and we derive two EM algorithms. The first one considers a fixed weight for each observation. The second one treats each weight as a random variable following a gamma distribution. We propose a model selection method based on a minimum message length criterion, provide a weight initialization strategy, and validate the proposed algorithms by comparing them with several state of the art parametric and non-parametric clustering techniques. We also demonstrate the effectiveness and robustness of the proposed clustering technique in the presence of heterogeneous data, namely audio-visual scene analysis.Comment: 14 pages, 4 figures, 4 table
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