5,582 research outputs found
Electrochemical Data, Part IV Quarterly Report, Jul. 1 - Sep. 30, 1966
Electrolytic equivalent conductance values of hydrochloric aci
A new substrate for sampling deep river macroinvertebrates
We compared macroinvertebrate communities colonising multiplate samplers constructed from perspex or tempered hardboard (wood) with an alternative artificial substrate constructed from folded coconut fibre matting (coir) enclosed in nylon netting. Substrates were incubated for 62 days over January to March 2007 at six sites over 240 km along the Waikato River. The three substrates supported similar numbers of invertebrate taxa (27 - 29 taxa), but coir samples contained 71% of total invertebrate numbers from all substrates combined, compared with <17% for each type of multiplate sampler. Coir faunas were heavily dominated by the hydrobiid snail Potamopyrgus (84 % of numbers), and this taxon along with the amphipod Paracalliope comprised 58 - 66 % of invertebrates on both types of multiplate samplers. Analysis of a Bray-Curtis matrix suggested statistically significant differences in percent community composition between coir samplers and each type of multiplate sampler over the late summer study period. Densities per cm3 of Oligochaeta, Mollusca, and "other worms" (Platyhelminthes, Rhabdocoela, Nemertea and Hirudinea combined) were significantly higher in coir samples than one or both of the multiplate samplers. Results suggest coir samplers may provide a useful supplement to multiplate samplers for deep river invertebrate studies by collecting a different range of taxa, including those favouring cover and characteristic of depositional environments
Electrochemical data. Part 12 - Electrolytic conductivity of aqueous solutions of the sodium halides
Electrolytic conductivity of aqueous solutions of sodium halide
Electrochemical Data, Part V Quarterly Report, Oct. 1 - Dec. 31, 1966
Electrolytic conductance of hydriodic aci
Decoupled and linear quadratic regulator control of a large, flexible space antenna with an observer in the control loop
An analysis is performed to compare decoupled and linear quadratic regulator (LQR) procedures for the control of a large, flexible space antenna. Control objectives involve: (1) commanding changes in the rigid-body modes, (2) nulling initial disturbances in the rigid-body modes, or (3) nulling initial disturbances in the first three flexible modes. Control is achieved with two three-axis control-moment gyros located on the antenna column. Results are presented to illustrate various effects on control requirements for the two procedures. These effects include errors in the initial estimates of state variables, variations in the type, number, and location of sensors, and deletions of state-variable estimates for certain flexible modes after control activation. The advantages of incorporating a time lag in the control feedback are also illustrated. In addition, the effects of inoperative-control situations are analyzed with regard to control requirements and resultant modal responses. Comparisons are included which show the effects of perfect state feedback with no residual modes (ideal case). Time-history responses are presented to illustrate the various effects on the control procedures
Effect of low-level, low-frequency electric fields on EEG and behavior in Macaca nemestrina
Effect of low level, low frequency electric fields on EEG and behavior of Macaca nemestrin
Secular changes in mid-adulthood body mass index, waist circumference, and low HDL cholesterol between 1990, 2003, and 2018 in Great Britain
Objective:
To investigate the extent to which (1) secular changes in mid-adulthood WC are independent of BMI and (2) secular changes in low HDL-C are dependent on WC in each sex. /
Methods:
The sample comprised 19,406 adults (aged 43–47 years) from three birth cohort studies with BMI and WC measured in 1990, 2003, or 2018; 13,239 participants additionally had HDL-C measured in 2003 or 2018. Quantile regression was used to model differences between 1990–2003 and 2003–2018 in (1) BMI and WC internal Z-scores and (2) WC in cm before and after adjustment for BMI. Binary logistic regression was used to model differences between 2003 and 2018 in low HDL-C, before and after adjustment for BMI or WC. /
Results:
Secular increases in BMI and WC were larger between 1990 and 2003 than 2003 and 2018 and at the upper ends of the distributions. At the 85th quantile, effect sizes were larger for WC than BMI Z-scores in females but not males. Adjustment for BMI attenuated estimates of secular increases in WC in cm more in males than females. Odds ratios for low HDL-C in 2018 compared to 2003 were 1.73 (95% CI 1.32, 2.28) in males and 1.34 (1.01, 1.78) in females. Adjustment for WC did not substantially change the estimate in males but attenuated the estimate for females to 1.09 (0.81, 1.47). /
Conclusions:
In women much more so than in men, secular increases in mid-adulthood WC appear to have occurred independently of BMI and largely explain the observed rise in low HDL-C prevalence between 2003 and 2018
An Application of Feynman-Kleinert Approximants to the Massive Schwinger Model on a Lattice
A trial application of the method of Feynman-Kleinert approximants is made to
perturbation series arising in connection with the lattice Schwinger model. In
extrapolating the lattice strong-coupling series to the weak-coupling continuum
limit, the approximants do not converge well. In interpolating between the
continuum perturbation series at large fermion mass and small fermion mass,
however, the approximants do give good results. In the course of the
calculations, we picked up and rectified an error in an earlier derivation of
the continuum series coefficients.Comment: 16 pages, 4 figures, 5 table
Critical Behaviour of One-particle Spectral Weights in the Transverse Ising Model
We investigate the critical behaviour of the spectral weight of a single
quasiparticle, one of the key observables in experiment, for the particular
case of the transverse Ising model.Series expansions are calculated for the
linear chain and the square and simple cubic lattices. For the chain model, a
conjectured exact result is discovered. For the square and simple cubic
lattices, series analyses are used to estimate the critical exponents. The
results agree with the general predictions of Sachdev.Comment: 4 pages, 3 figure
Ground state parameters, finite-size scaling, and low-temperature properties of the two-dimensional S=1/2 XY model
We present high-precision quantum Monte Carlo results for the S=1/2 XY model
on a two-dimensional square lattice, in the ground state as well as at finite
temperature. The energy, the spin stiffness, the magnetization, and the
susceptibility are calculated and extrapolated to the thermodynamic limit. For
the ground state, we test a variety of finite-size scaling predictions of
effective Lagrangian theory and find good agreement and consistency between the
finite-size corrections for different quantities. The low-temperature behavior
of the susceptibility and the internal energy is also in good agreement with
theoretical predictions.Comment: 6 pages, 8 figure
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