442 research outputs found

    United States Gypsum\u27s Heath Plant

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    The United States Gypsum Company\u27s Heath plant, which is located at Heath, Montana, is one of forty-six diversified production facilities for the development and production of gypsum products. The Heath plant is located about twelve miles southeast of Lewistown, Montana, and consists of a mine, a mill and a boardplant. The Heath plant was built in 1925 by the Northwestern Gypsum Company

    Leaching, Purification and Precipitation of Glen Scheelite Concentrates

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    The leaching, purification and precipitation of the Glen scheelite concentrates were performed to acquaint the student with the equipment and processes involved. The concentrates were obtained through the courtesy of the Minerals Engineering Company. Leaching was carried out in the high-pressure autoclave; whereas the purification and precipitation were carried out in laboratory beakers

    The Implications of the Working Memory Model for the Evolution of Modern Cognition

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    What distinguishes the cognition of biologically modern humans from that of more archaic populations such as Neandertals? The norm in paleoanthropology has been to emphasize the role of language and symbolism. But the modern mind is more than just an archaic mind enhanced by symbol use. It also possesses an important problem solving and planning component. In cognitive neuroscience these advanced planning abilities have been extensively investigated through a formal model known as working memory. The working memory model is now well-enough established to provide a powerful lens through which paleoanthropologists can view the fossil and archaeological records. The challenge is methodological. The following essay reviews the controversial hypothesis that a recent enhancement of working memory capacity was the final piece in the evolution of modern cognition

    Charles Leonard Bouton

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    Beyond Symbolism and Language

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    Despite 20 years of concerted attention, paleoanthropology has established little of substance concerning the evolution of the modern mind, if by substance we mean conclusions that would be of interest and use to scholars of human cognition. Part of this failure can be linked to a poverty of appropriate interpretive concepts. There is more to the modern mind than symbolism and language, the two "abilities" most often cited in the paleoanthropological literature. Modern humans have a sophisticated ability to make and execute elaborate plans of action, something known in the cognitive science literature as executive functions. Cognitive science has further established that these executive functions are enabled by working memory, an interpretive concept introduced by Alan Baddeley in 1974 and subsequently tested by more than 30 years of intensive research. Recently, Coolidge and Wynn have advanced a controversial hypothesis that it was an enhancement of working-memory capacity that powered the final evolution of the modern mind. Wenner-Gren International Symposium 139 met in March 2008 in Cascais, Portugal, to discuss this hypothesis and the evolution of working memory and executive reasoning in general. Consider the following scenarios: 1. A Kansas farmer planted 25% more acreage in maize despite having had a poor harvest the previous year and despite the marginal condition of his land (in terms of rainfall) for maize production. When asked why he had chosen to do this, he replied that the price of crude oil had risen above $100 a barrel. 2. Toward the end of the rainy season, a hunter-gatherer in Western Australia sets an intentional bushfire and burns a sizeable tract of land. This results in a second green-up, which attracts the herbivores that are an important component of his diet. A year later, he sets fire to a different tract of land; he does not return to the original tract for more than a decade

    The harmonic oscillator on Riemannian and Lorentzian configuration spaces of constant curvature

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    The harmonic oscillator as a distinguished dynamical system can be defined not only on the Euclidean plane but also on the sphere and on the hyperbolic plane, and more generally on any configuration space with constant curvature and with a metric of any signature, either Riemannian (definite positive) or Lorentzian (indefinite). In this paper we study the main properties of these `curved' harmonic oscillators simultaneously on any such configuration space, using a Cayley-Klein (CK) type approach, with two free parameters \ki, \kii which altogether correspond to the possible values for curvature and signature type: the generic Riemannian and Lorentzian spaces of constant curvature (sphere S2{\bf S}^2, hyperbolic plane H2{\bf H}^2, AntiDeSitter sphere {\bf AdS}^{\unomasuno} and DeSitter sphere {\bf dS}^{\unomasuno}) appear in this family, with the Euclidean and Minkowski spaces as flat limits. We solve the equations of motion for the `curved' harmonic oscillator and obtain explicit expressions for the orbits by using three different methods: first by direct integration, second by obtaining the general CK version of the Binet's equation and third, as a consequence of its superintegrable character. The orbits are conics with centre at the potential origin in any CK space, thereby extending this well known Euclidean property to any constant curvature configuration space. The final part of the article, that has a more geometric character, presents those results of the theory of conics on spaces of constant curvature which are pertinent.Comment: 29 pages, 6 figure

    Some integrals ocurring in a topology change problem

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    In a paper presented a few years ago, De Lorenci et al. showed, in the context of canonical quantum cosmology, a model which allowed space topology changes (Phys. Rev. D 56, 3329 (1997)). The purpose of this present work is to go a step further in that model, by performing some calculations only estimated there for several compact manifolds of constant negative curvature, such as the Weeks and Thurston spaces and the icosahedral hyperbolic space (Best space).Comment: RevTeX article, 4 pages, 1 figur

    The prehistory of number concept

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    AbstractCarey leaves unaddressed an important evolutionary puzzle: In the absence of a numeral list, how could a concept of natural number ever have arisen in the first place? Here we suggest that the initial development of natural number must have bootstrapped on a material culture scaffold of some sort, and illustrate how this might have occurred using strings of beads.</jats:p

    Counting and computing regions of DD-decomposition: algebro-geometric approach

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    New methods for DD-decomposition analysis are presented. They are based on topology of real algebraic varieties and computational real algebraic geometry. The estimate of number of root invariant regions for polynomial parametric families of polynomial and matrices is given. For the case of two parametric family more sharp estimate is proven. Theoretic results are supported by various numerical simulations that show higher precision of presented methods with respect to traditional ones. The presented methods are inherently global and could be applied for studying DD-decomposition for the space of parameters as a whole instead of some prescribed regions. For symbolic computations the Maple v.14 software and its package RegularChains are used.Comment: 16 pages, 8 figure

    Weisskopf-Wigner model for wave packet excitation

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    We consider a laser induced molecular excitation process as a decay of a single energy state into a continuum. The analytic results based on Weisskopf-Wigner approach and perturbation calculations are compared with numerical wave packet results. We find that the decay model describes the excitation process well within the expected parameter region.Comment: 14 pages, Latex2.09, 9 Postscript figures embedded using psfig, see also http://www.physics.helsinki.fi/~kasuomin
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