82 research outputs found

    The Ising Susceptibility Scaling Function

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    We have dramatically extended the zero field susceptibility series at both high and low temperature of the Ising model on the triangular and honeycomb lattices, and used these data and newly available further terms for the square lattice to calculate a number of terms in the scaling function expansion around both the ferromagnetic and, for the square and honeycomb lattices, the antiferromagnetic critical point.Comment: PDFLaTeX, 50 pages, 5 figures, zip file with series coefficients and background data in Maple format provided with the source files. Vs2: Added dedication and made several minor additions and corrections. Vs3: Minor corrections. Vs4: No change to eprint. Added essential square-lattice series input data (used in the calculation) that were removed from University of Melbourne's websit

    EuFe2_2As2_2 under high pressure: an antiferromagnetic bulk superconductor

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    We report the ac magnetic susceptibility χac\chi_{ac} and resistivity ρ\rho measurements of EuFe2_2As2_2 under high pressure PP. By observing nearly 100% superconducting shielding and zero resistivity at PP = 28 kbar, we establish that PP-induced superconductivity occurs at Tc∌T_c \sim~30 K in EuFe2_2As2_2. ρ\rho shows an anomalous nearly linear temperature dependence from room temperature down to TcT_c at the same PP. χac\chi_{ac} indicates that an antiferromagnetic order of Eu2+^{2+} moments with TN∌T_N \sim~20 K persists in the superconducting phase. The temperature dependence of the upper critical field is also determined.Comment: To appear in J. Phys. Soc. Jpn., Vol. 78 No.

    Reference redox systems in tetrahydrofuran

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    Ferrocene and bis(biphenyl)chromium have been proposed as reference redox systems for non-aqueous electrochemistry. These materials have been tested for use in tetrahydrofuran solutions by cyclic voltammetry and polarography which confirmed the expected difference between their reaction potentials. Both materials are suitable for practical referencing, covering complementary potential ranges, but bis(biphenyl)chromium would normally be preferred

    Effective aerodynamic roughness estimated from airborne laser altimeter measurements of surface features

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    Aerodynamic roughness length (z0) and displacement height (d0) are important surface parameters for estimating surface fluxes in numerical models. These parameters are generally determined from wind flow characteristics using logarithmic wind profiles measured at a meteorological tower or by balloon release. It would be an advantage to use measurements of land surface characteristics instead of wind flow characteristics to estimate the z0 and d0 for large areas. Important land surface characteristics are the size and distribution of roughness elements (obstacles). This research evaluates the use of high resolution laser altimeter data to obtain these land surface characteristics. Data were collected at the US Department of Agriculture, Agricultural Research Service (USDA-ARS), Jornada Experimental Range in southern New Mexico, USA over a coppice dune dominated area. These dunes are covered by honey mesquite (Prosopis glandulosa Torr.) with flat and mostly bare interdunal areas. For this analysis, three 450m laser transects with a 2 cm measurement interval were used. The distribution and size of dunes were calculated from these laser transects and used to compute z0. Analysis gave an average z0=4.3 cm and d0=70 cm for the three laser transects, which compares to z0=7±4 cm and d0=98±48 cm calculated from wind profile data measured at a 10m tower near the laser transects. These results show that the estimation of z0 and d0 for a complex terrain is possible using simple land surface features computed from high resolution laser altimeter data.

    Measuring intracompartmental pressures for the chronic exertional compartment syndrome: Challenging commercially available devices and their respective accuracy

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    The aim of this study was to compare commercially available manometers and needles used for intracompartmental pressure measurements for accuracy. An experimental compartment simulation model was developed in order to compare four different terminal devices (Compass manometer, Stryker device, Meritrans transducer, and arterial line) and 22 types of needles. First, all possible device/needle combinations were introduced in rubber ports at the bottom of a water column. The water column was gradually drained three times for each device/needle combination and pressures were recorded by two researchers. This procedure was repeated after placement of a sample of homogenous porcine gluteal muscle tissue. When measuring the fluid column only, all Intraclass Correlation Coefficients were found to be ≄0.980, indicating good resemblance to the reference pressure. After addition of the muscle tissue to the experimental set up, accuracy of the Stryker device and arterial line remained the same. The accuracy of the Compass manometer and Meritrans transducer became less. Excellent reliability was found for 7 out of 22 needles when combined with the Stryker device and for 2 out of 22 needles when combined with the arterial line. The four terminal devices tested were all accurate when measuring pressure in a water column, whereas only the Stryker device and arterial line accurately represented the water column pressure in a porcine gluteal muscle model. Future research will have to verify whether these results can be repeated in human cadaver models and in vivo
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