26,805 research outputs found

    Fluid velocity measuring device

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    A fluid velocity measuring device is described which, when placed in a freestream fluid flow, causes vortices to be formed at a frequency proportional to the flow rate of the fluid. Sensors on the device generate electric signals with frequency proportional to the rate of vortex creation and with relative mean amplitudes indicative of fluid flow direction. Electric circuitry translates the electric signals into indications of fluid speed and direction

    Loss of dependence on IGF-1 for proliferation of human thyroid adenoma cells.

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    The proliferative responses to IGF-1 (Somatomedin C) and TSH, as assessed by 3H-thymidine (3H-TdR) incorporation and autoradiographic labelling index (LI), of suspension and monolayer cultures of human thyroid follicular epithelium derived from both normal and adenoma tissue have been compared. In cultures of normal follicles, whilst neither TSH nor IGF-1 alone produced any effect, a combination of TSH (0.1 mU ml-1) together with IGF-1 (10 ng ml-1) induced a highly significant proliferative response as shown by a peak of 3HTdR incorporation and LI, 4-5 days after growth factor addition. The TSH concentration-effect curve was bell-shaped, a higher concentration of TSH (10 mU ml-1) resulting in a reduced response. In cultures derived from adenoma tissue, however, TSH alone at 0.1 mU ml-1 was sufficient to permit a highly significant proliferative response (equivalent to, or greater than the normal) in 4 out of 5 adenomas examined; again a higher concentration of TSH (10 mU ml-1) resulted in a diminished response. Addition of IGF-1 (10 ng ml-1) produced no significant change in the response to TSH (0.1 mU ml-1) in 3 of these 4 adenomas, and significantly inhibited the response in the fourth adenoma. It is concluded that escape from the requirement for an exogenous source of IGF-1 may be a key step in the development of human thyroid epithelial (follicular cell) neoplasia

    Scale-free networks in complex systems

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    In the past few years, several studies have explored the topology of interactions in different complex systems. Areas of investigation span from biology to engineering, physics and the social sciences. Although having different microscopic dynamics, the results demonstrate that most systems under consideration tend to self-organize into structures that share common features. In particular, the networks of interaction are characterized by a power law distribution, P(k)kαP(k)\sim k^{-\alpha}, in the number of connections per node, kk, over several orders of magnitude. Networks that fulfill this propriety of scale-invariance are referred to as ``scale-free''. In the present work we explore the implication of scale-free topologies in the antiferromagnetic (AF) Ising model and in a stochastic model of opinion formation. In the first case we show that the implicit disorder and frustration lead to a spin-glass phase transition not observed for the AF Ising model on standard lattices. We further illustrate that the opinion formation model produces a coherent, turbulent-like dynamics for a certain range of parameters. The influence, of random or targeted exclusion of nodes is studied.Comment: 9 pages, 4 figures. Proceeding to "SPIE International Symposium Microelectronics, MEMS, and Nanotechnology", 11-15 December 2005, Brisbane, Australi

    In-medium electron-nucleon scattering

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    In-medium nucleon electromagnetic form factors are calculated in the quark meson coupling model. The form factors are typically found to be suppressed as the density increases. For example, at normal nuclear density and Q20.3GeV2Q^2 \sim 0.3 { GeV}^2, the nucleon electric form factors are reduced by approximately 8% while the magnetic form factors are reduced by only 1 - 2%. These variations are consistent with current experimental limits but should be tested by more precise experiments in the near future.Comment: 14 pages, latex, 3 figure

    Phase transition from quark-meson coupling hyperonic matter to deconfined quark matter

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    We investigate the possibility and consequences of phase transitions from an equation of state (EOS) describing nucleons and hyperons interacting via mean fields of sigma, omega, and rho mesons in the recently improved quark-meson coupling (QMC) model to an EOS describing a Fermi gas of quarks in an MIT bag. The transition to a mixed phase of baryons and deconfined quarks, and subsequently to a pure deconfined quark phase, is described using the method of Glendenning. The overall EOS for the three phases is calculated for various scenarios and used to calculate stellar solutions using the Tolman-Oppenheimer-Volkoff equations. The results are compared with recent experimental data, and the validity of each case is discussed with consequences for determining the species content of the interior of neutron stars.Comment: 12 pages, 14 figures; minor typos correcte

    Precise determination of the strangeness magnetic moment of the nucleon

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    By combining the constraints of charge symmetry with new chiral extrapolation techniques and recent low mass lattice QCD simulations of the individual quark contributions to the magnetic moments of the nucleon octet, we obtain a precise determination of the strange magnetic moment of the proton. The result, namely G_M^s = -0.046 +/- 0.019 mu_N, is consistent with the latest experimental measurements but an order of magnitude more precise. This poses a tremendous challenge for future experiments.Comment: 4 pages, 7 figures. Submitted to Phys. Rev. Lett. Clairification of manuscript and improved correlation function analysi

    The Development of a Naturalistic Self-Management Inventory

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    The most common approach to self-management research has been to apply it to a specific target behavior, without attending to the generalizability of changes to other facets of one\u27s life. A procedure for measuring self-management effectiveness under real world conditions was developed which emphasized the successful application of self-change procedures. The Self-Description Form (SDF) was field-tested on a sample of four groups of college students (N=214). Results indicated that normative self-management scores increased as level of education increased. Females had higher self-management scores than males except on the leisure scale. The reliability of the self-description scale was confirmed although validity efforts are still in the preliminary stages of analysis. When fully developed, the form may be useful in evaluating counseling and educational programs and in predicting an individual\u27s future effectiveness in leisure, health, social and work activities. Several tables and figures are provided to illustrate SDF reliability and validity
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