4,443 research outputs found

    Statistical mechanics of ontology based annotations

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    We present a statistical mechanical theory of the process of annotating an object with terms selected from an ontology. The term selection process is formulated as an ideal lattice gas model, but in a highly structured inhomogeneous field. The model enables us to explain patterns recently observed in real-world annotation data sets, in terms of the underlying graph structure of the ontology. By relating the external field strengths to the information content of each node in the ontology graph, the statistical mechanical model also allows us to propose a number of practical metrics for assessing the quality of both the ontology, and the annotations that arise from its use. Using the statistical mechanical formalism we also study an ensemble of ontologies of differing size and complexity; an analysis not readily performed using real data alone. Focusing on regular tree ontology graphs we uncover a rich set of scaling laws describing the growth in the optimal ontology size as the number of objects being annotated increases. In doing so we provide a further possible measure for assessment of ontologies.Comment: 27 pages, 5 figure

    Interpretations of the Accelerating Universe

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    It is generally argued that the present cosmological observations support the accelerating models of the universe, as driven by the cosmological constant or `dark energy'. We argue here that an alternative model of the universe is possible which explains the current observations of the universe. We demonstrate this with a reinterpretation of the magnitude-redshift relation for Type Ia supernovae, since this was the test that gave a spurt to the current trend in favour of the cosmological constant.Comment: 12 pages including 2 figures, minor revision, references added, a paragraph on the interpretation of the CMB anisotropy in the QSSC added in conclusion, general results unchanged. To appear in the October 2002 issue of the "Publications of the Astronmical Society of the Pacific

    The cosmological BCS mechanism and the Big Bang Singularity

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    We provide a novel mechanism that resolves the Big Bang Singularity present in FRW space-times without the need for ghost fields. Building on the fact that a four-fermion interaction arises in General Relativity when fermions are covariantly coupled, we show that at early times the decrease in scale factor enhances the correlation between pairs of fermions. This enhancement leads to a BCS-like condensation of the fermions and opens a gap dynamically driving the Hubble parameter HH to zero and results in a non-singular bounce, at least in some special cases.Comment: replaced to match the journal versio

    CHARACTERISTICS AND PURIFICATION OF INDOLEACETIC ACID OXIDASE IN YELLOW BIRCH

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    Properties of a future susy universe

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    In the string landscape picture, the effective potential is characterized by an enormous number of local minima of which only a minuscule fraction are suitable for the evolution of life. In this "multiverse", random transitions are continually made between the various minima with the most likely transitions being to minima of lower vacuum energy. The inflationary era in the very early universe ended with such a transition to our current phase which is described by a broken supersymmetry and a small, positive vacuum energy. However, it is likely that an exactly supersymmetric (susy) phase of zero vacuum energy as in the original superstring theory also exists and that, at some time in the future, there will be a transition to this susy world. In this article we make some preliminary estimates of the consequences of such a transition.Comment: 17 pages, 3 figures; intermediate extensions/revisions available at http://www.bama.ua.edu/~lclavell/Susyria.pd

    Elastomeric Adhesive Properties-Shear Strength, Shear Modulus, Creep, and Recovery

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    Three commercially available adhesives, approved for use in field glued floor systems, were evaluated for potential structural application in light frame wood buildings. All had adequate static shear strength for common floor and roof sheathing uses. Two were sufficiently rigid to generate useful composite action. One displayed relative creep compatible with wood structural design practice but two had excessive relative creep. The adhesive with good creep properties also had good recovery properties. The other two had poor recovery properties. One adhesive that had good shear strength in a conventional block shear test would not consistently sustain stress as low as 25 psi for more than four days. All tests were conducted on bonded wood specimens at 70 F (21 C) and 12% EMC

    Cosmic Needles versus Cosmic Microwave Background Radiation

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    It has been suggested by a number of authors that the 2.7K cosmic microwave background (CMB) radiation might have arisen from the radiation from Population III objects thermalized by conducting cosmic graphite/iron needle-shaped dust. Due to lack of an accurate solution to the absorption properties of exceedingly elongated grains, in existing literature which studies the CMB thermalizing process they are generally modelled as (1) needle-like spheroids in terms of the Rayleigh approximation; (2) infinite cylinders; and (3) the antenna theory. We show here that the Rayleigh approximation is not valid since the Rayleigh criterion is not satisfied for highly conducting needles. We also show that the available intergalactic iron dust, if modelled as infinite cylinders, is not sufficient to supply the required opacity at long wavelengths to obtain the observed isotropy and Planckian nature of the CMB. If appealing to the antenna theory, conducting iron needles with exceedingly large elongations (10^4) appear able to provide sufficient opacity to thermalize the CMB within the iron density limit. But the applicability of the antenna theory to exceedingly thin needles of nanometer/micrometer in thickness needs to be justified.Comment: 13 pages, 4 figures; submitted to ApJ

    What and how: doing good research with young people, digital intimacies, and relationships and sex education

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    © 2020, © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. As part of a project funded by the Wellcome Trust, we held a one-day symposium, bringing together researchers, practitioners, and policymakers, to discuss priorities for research on relationships and sex education (RSE) in a world where young people increasingly live, experience, and augment their relationships (whether sexual or not) within digital spaces. The introduction of statutory RSE in schools in England highlights the need to focus on improving understandings of young people and digital intimacies for its own sake, and to inform the development of learning resources. We call for more research that puts young people at its centre; foregrounds inclusivity; and allows a nuanced discussion of pleasures, harms, risks, and rewards, which can be used by those working with young people and those developing policy. Generating such research is likely to be facilitated by participation, collaboration, and communication with beneficiaries, between disciplines and across sectors. Taking such an approach, academic researchers, practitioners, and policymakers agree that we need a better understanding of RSE’s place in lifelong learning, which seeks to understand the needs of particular groups, is concerned with non-sexual relationships, and does not see digital intimacies as disconnected from offline everyday ‘reality’
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