56,626 research outputs found

    Design for diagnostics and prognostics:a physical- functional approach

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    Building info-skills by degrees : embedding information literacy in university study

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    Late last year teaching staff at Griffith University participated in a symposium entitled 'Spotlight on Generic Skills & Flexible Learning'. This event brought together academic staff as well as library staff, learning advisers and other support staff interested in teaching and learning issues. The discussion was based on the premise that the University has a responsibility to ensure that its courses emphasise broad educational values and 'produce highly sought after graduates with globally applicable skills for the international market'(1). It was acknowledged that the University consistently scores very highly with graduates for its development of generic skills. However at the same time staff expressed concern at the challenge of developing more flexible, student-centred learning environments that have generic skills embedded across all programs (2). As a result there has been much debate in the University about which skills are important, how they will be acquired and how they could effectively be built into the curriculum. One outcome of these discussions is the project described in this paper. What follows is an overview of the project and a discussion about the integration and development of information literacy as a generic attribute in the curriculum and some suggestions on ways forward

    Nonabelian Duality and Solvable Large N Lattice Systems

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    We introduce the basics of the nonabelian duality transformation of SU(N) or U(N) vector-field models defined on a lattice. The dual degrees of freedom are certain species of the integer-valued fields complemented by the symmetric groups' \otimes_{n} S(n) variables. While the former parametrize relevant irreducible representations, the latter play the role of the Lagrange multipliers facilitating the fusion rules involved. As an application, I construct a novel solvable family of SU(N) D-matrix systems graded by the rank 1\leq{k}\leq{(D-1)} of the manifest [U(N)]^{\oplus k} conjugation-symmetry. Their large N solvability is due to a hidden invariance (explicit in the dual formulation) which allows for a mapping onto the recently proposed eigenvalue-models \cite{Dub1} with the largest k=D symmetry. Extending \cite{Dub1}, we reconstruct a D-dimensional gauge theory with the large N free energy given (modulo the volume factor) by the free energy of a given proposed 1\leq{k}\leq{(D-1)} D-matrix system. It is emphasized that the developed formalism provides with the basis for higher-dimensional generalizations of the Gross-Taylor stringy representation of strongly coupled 2d gauge theories.Comment: TeX, 46 page

    Surface transects for arsenic speciation, antimony speciation, and alkaline phosphatase activity from R/V Knorr cruise KN204-01 in the Subtropical North Atlantic Ocean in 2011 (U.S. GEOTRACES NAT project)

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    Dataset: GT11 - As AP Surface TransectsSurface transects for arsenic speciation, antimony speciation, and alkaline phosphatase activity. Data for the concentrations of the dissolved (<0.4 µm) arsenic species: total inorganic As (III+V), arsenite (AsIII), As(V), monomethyl As, dimethyl As, and the activity of the enzyme alkaline phosphatase (unfiltered). For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3830NSF Division of Ocean Sciences (NSF OCE) OCE-0926423, NSF Division of Ocean Sciences (NSF OCE) OCE-092609

    A conjugation-free geometric presentation of fundamental groups of arrangements II: Expansion and some properties

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    A conjugation-free geometric presentation of a fundamental group is a presentation with the natural topological generators x1,...,xnx_1, ..., x_n and the cyclic relations: xikxik1...xi1=xik1...xi1xik=...=xi1xik...xi2x_{i_k}x_{i_{k-1}} ... x_{i_1} = x_{i_{k-1}} ... x_{i_1} x_{i_k} = ... = x_{i_1} x_{i_k} ... x_{i_2} with no conjugations on the generators. We have already proved that if the graph of the arrangement is a disjoint union of cycles, then its fundamental group has a conjugation-free geometric presentation. In this paper, we extend this property to arrangements whose graphs are a disjoint union of cycle-tree graphs. Moreover, we study some properties of this type of presentations for a fundamental group of a line arrangement's complement. We show that these presentations satisfy a completeness property in the sense of Dehornoy, if the corresponding graph of the arrangement has no edges. The completeness property is a powerful property which leads to many nice properties concerning the presentation (such as the left-cancellativity of the associated monoid and yields some simple criterion for the solvability of the word problem in the group).Comment: 17 pages, 9 figures; final version, which corrects a mistake in the published versio

    Ultrafilter spaces on the semilattice of partitions

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    The Stone-Cech compactification of the natural numbers bN, or equivalently, the space of ultrafilters on the subsets of omega, is a well-studied space with interesting properties. If one replaces the subsets of omega by partitions of omega, one can define corresponding, non-homeomorphic spaces of partition ultrafilters. It will be shown that these spaces still have some of the nice properties of bN, even though none is homeomorphic to bN. Further, in a particular space, the minimal height of a tree pi-base and P-points are investigated

    Fast Bayesian inference for slow-roll inflation

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    We present and discuss a new approach increasing by orders of magnitude the speed of performing Bayesian inference and parameter estimation within the framework of slow-roll inflation. The method relies on the determination of an effective likelihood for inflation which is a function of the primordial amplitude of the scalar perturbations complemented with the necessary number of the so-called Hubble flow functions to reach the desired accuracy. Starting from any cosmological data set, the effective likelihood is obtained by marginalisation over the standard cosmological parameters, here viewed as "nuisance" from the early Universe point of view. As being low-dimensional, basic machine-learning algorithms can be trained to accurately reproduce its multidimensional shape and then be used as a proxy to perform fast Bayesian inference on the inflationary models. The robustness and accuracy of the method are illustrated using the Planck Cosmic Microwave Background (CMB) data to perform primordial parameter estimation for the large field models of inflation. In particular, marginalised over all possible reheating history, we find the power index of the potential to verify p < 2.3 at 95% of confidence.Comment: 10 pages, 4 figures, uses mn2e. References added, matches published versio

    Dark Matter, Modified Gravity and the Mass of the Neutrino

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    It has been suggested that Einstein's theory of General Relativity can be modified to accomodate mismatches between the gravitational field and luminous matter on a wide range of scales. Covariant theories of modified gravity generically predict the existence of extra degrees of freedom which may be interpreted as dark matter. We study a subclass of these theories where the overall energy density in these extra degrees of freedom is subdominant relative to the baryon density and show that they favour the presence of massive neutrinos. For some specific cases (such as a flat Universes with a cosmological constant) one finds a conservative lower bound on the neutrinos mass of mν>0.31m_\nu>0.31 eV.Comment: 5 pages, 2 figures, 2 tables, submitted to Phys. Rev.

    A Note on Circle Compactification of Tensile Ambitwistor String

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    We discuss a number of problems associated with the circle compactification of the bosonic tensile ambitwistor string with the asymmetric vacuum choice. By considering the spectrum and physical state conditions, we show that the circle radius plays a role as a tuning parameter which determines the low energy effective field theory. At the self dual point, we construct the current operators and compute OPEs between them. While the final outcome remains as yet inconclusive, several new results are obtained. Through the current algebra analysis we show that there is a subsector of the massless states where the gauge symmetry is enhanced to ISO(2)L×SU(2)RISO(2)_L\times SU(2)_R. Using the fact that the one loop partition function is not modular invariant, we show that tensile ambitwistor string partition function is exactly the same as a field theory partition function. Our result proves that despite the existence of winding modes, which is a typical characteristic of a string, the tensile ambitwistor string behaves as a point particle theory.Comment: 31 pages, v2: minor corrections, reference added, published in Nucl.Phys.
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