80,190 research outputs found

    Are you a researcher as well as a medical illustrator?

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    When we list the areas of practice for medical illustrators we always include research, but how involved in research are we? The aim of this activity is to encourage your professional development not just as a medical illustrator but your involvement with research whether that is undertaking your own research, undertaking evidence based practice (1) , working as part of a research team, advising researchers on the value of medical illustration or supporting a student undertaking a research project for their degree or post-graduate qualification

    Free energies in the presence of electric and magnetic fields

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    We discuss different free energies for materials in static electric and magnetic fields. We explain what the corresponding Hamiltonians are, and describe which choice gives rise to which result for the free energy change, dF, in the thermodynamic identity. We also discuss which Hamiltonian is the most appropriate for calculations using statistical mechanics, as well as the relationship between the various free energies and the "Landau function", which has to be minimized to determine the equilibrium polarization or magnetization, and is central to Landau's theory of second order phase transitions

    An implementation of a reference symbol approach to generic modulation in fading channels

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    As mobile satellite communications systems evolve over the next decade, they will have to adapt to a changing tradeoff between bandwidth and power. This paper presents a flexible approach to digital modulation and coding that will accommodate both wideband and narrowband schemes. This architecture could be the basis for a family of modems, each satisfying a specific power and bandwidth constraint, yet all having a large number of common signal processing blocks. The implementation of this generic approach, with general purpose digital processors for transmission of 4.8 kilobits per sec. digitally encoded speech, is described

    The Molecular Gas Distribution and Schmidt Law in M33

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    The relationship between the star formation rate and surface density of neutral gas within the disk of M33 is examined with new imaging observations of CO J=1-0 emission gathered with the FCRAO 14m telescope and IRAS HiRes images of the 60 micron and 100 micron emission. The Schmidt law, Sigma_SFR ~ Sigma_gas^n, is constructed using radial profiles of the HI 21cm, CO, and far infrared emission. A strong correlation is identified between the star formation rate and molecular gas surface density. This suggests that the condensation of giant molecular clouds is the limiting step to star formation within the M33 disk. The corresponding molecular Schmidt index, n_{mol}, is 1.36 +/- 0.08. The star formation rate has a steep dependence on total mass gas surface density, (Sigma_{HI}+Sigma_{H_2}), owing to the shallow radial profile of the atomic gas which dominates the total gas surface density for most radii. The disk pressure of the gas is shown to play a prominent role in regulating the molecular gas fraction in M33.Comment: 19 pages + 5 figures. Accepted for publication in Ap

    A SPATIAL VIEW OF THE NEGATIVE BINOMIAL PARAMETER k WHEN DESCRIBING INSECT POPULATIONS

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    Measures of aggregation as applied to insect populations are reviewed. When these measures indicate strong aggregation, an aggregated spatial pattern is often assumed. The literature noting that the measure of aggregation does not necessarily indicate spatial aggregation, or the lack of it, is reviewed. Field data from four insect species are presented. In each case, the measures of aggregation indicated strong aggregation, but the spatial pattern was not significantly different from random

    THE 2-SPRT AS AN ALTERNATIVE TO WALD\u27S SPRT WHEN TESTING HYPOTHESES CONCERNING INSECT POPULATIONS

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    Exact and Wald\u27s approximations for the operating characteristic and average sample number functions are compared for a sequential probability ratio (SPRT) test commonly used in cotton integrated pest management (IPM) programs in southwestern Oklahoma. The 95th percentile of the sample size is also given. For the same set of hypotheses and stated error probabilities, the exact operating characteristic and average sample number functions and the 95th percentile of sample size are compared for the SPRT and 2-SPRT
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