Micromechanical "Trampoline" magnetometers for use in large pulsed magnetic fields

A silicon micromechanical magnetometer was constructed and successfully used in 60-tesla pulsed magnetic fields of less than 100-millisecond duration. The device is small, inexpensive to fabricate, and easy to use. It features a fast mechanical response (up to 50,000 hertz) and extremely high sensitivity yet is relatively robust against electrical and mechanical noise. Quantum oscillations in the magnetization of a 1-microgram sample of an organic superconductor, kappa-[bis(ethylenedithio)tetrathiafulvalene]2Cu(NCS)2, have been observed with this device.     

Anesthetic effects of different volumes of lidocaine for spermatic cord block in cattle

Objective

To evaluate three volumes of lidocaine for spermatic cord block to perform castration in cattle.

Evidence of sedimentation inequality along riparian areas colonised by Impatiens glandulifera (Himalayan balsam)

Soil loss from riparian areas supporting the annual invasive weed, Impatiens glandulifera (Himalayan balsam), was measured and compared with equivalent values recorded at nearby, topographically similar areas supporting perennial vegetation over a cumulative seven-year period, along sections of two separate river systems; one in Switzerland, and one in the UK. Soil loss from colonised locations was significantly greater than from reference locations in four of the seven measurement periods. Despite contrasting results, standard deviations, based on soil losses and gains, were predominantly higher for colonised areas at both rivers over most monitoring periods. These findings indicated that areas colonised by Himalayan balsam experience higher sediment flux in comparison with areas free of invasion. Here, we test those original interpretations by reinterrogating the datasets using a more robust analysis of inequality. Nine datasets were tested, five of which (i.e. 56%) showed that sediment flux was significantly greater at Himalayan balsam-invaded areas than at reference areas. Three datasets showed no difference in sediment flux between invaded and reference areas (33%), and one (11%) showed higher sediment flux at reference areas. Most results uphold our original interpretations and support our hypothesis that hydrochory probably dictates where colonisation initially occurs, by depositing Himalayan balsam seeds in slack or depressional areas along river margins. Once Himalayan balsam becomes established and sufficient perennial vegetation is displaced, seasonal die-off and depleted vegetation cover may increase the risk that some areas will experience significantly higher sediment flux.     

The kinetics of insecticide action. Part IV: the in-vivo distribution of pyrethroid insecticides during insect poisoning

The distribution of pyrethroids in insects has been studied using a combination of mathematical modelling and experimental observation. This approach has resulted in the formulation of a physiological model of the pharmaco-kinetics of cypermethrin applied topically to larvae of Spodoptera littoralis. Development of this model from simpler two- and three-compartment models is described. Simple models, whilst capable of complex behaviour, consider only the average rates and magnitudes of pharmaco-kinetic processes over whole animals, and cannot account for differences in concentration of insecticide between individual tissues. This can be achieved by using physiological models, but these require more experimental information for their validation. Moreover, unless simplifying assumptions are made, analytical solutions are not feasible for the large number of equations necessary to define such models. The modelling studies prompted an investigation of (1) in-vivo binding of insecticide to insect tissues, (2) the sizes of body compartments, and (3) the factors which affect the distribution of toxicant between these compartments. Binding has a marked effect on pharmacokinetic profiles and may result in oscillatory behaviour. During poisoning, the total bound cypermethrin increases proportionally to the cube root of the elapsed time. This results in a rapid rate of increase over early elapsed times (< 3h) which slows to approach a more linear form thereafter. Average sizes for the body compartments of larvae of Spodoptera littoralis Boisd, and the steady-state distribution of cypermethrin in these compartments are described. Although the haemolymph, which acts as the main distributive phase during poisoning, forms the largest compartment by volume, it has a low affinity for cypermethrin and distribution reaches steady state within 5 min after topical application. The nerve cord (the target tissue), which is the smallest compartment, has the highest steady-state concentration of cypermethrin. The distribution of cypermethrin in larval tissues is related to the ratios of tissue dry matter to water content.     

Age- and size-related trends in woody plant shoot development: regulatory pathways and evidence for genetic control

Woody plants exhibit significant and predictable patterns of change in morphology and physiology as they become older and larger. Four models of potential pathways controlling these changes are presented: a stimulus-response model in which fully developed organs respond to changes in environment (defined here as everything external to the organ); an extrinsic model in which the attributes of developing organs are determined by environmental factors; an intrinsic model in which changes are a result of programmed changes in gene expression; and an extrinsic-intrinsic model in which changes in gene expression are induced by environmental factors. We review evidence that a genetic component is involved in controlling age- and size-related changes in foliar morphology and physiology and discuss the possibility of complex interactions among model pathways.     

Dynamic model for the effects of K fertilizer on crop growth, K-uptake and soil-K in arable cropping. 2. Field test of the model

Abstract. The validity of the model described in Greenwood & Karpinets (1997) was tested against the results of single year, multi level K fertilizer experiments. Measurements of plant mass, %K in the plant and K activity ratio in soil had been made at harvest and at intervals during the growing season on spring wheat, summer cabbage and turnips. Reasonably good agreement was obtained between these measurements and simulated values when the two 'crop' parameters (defining the dependence of critical and maximum possible %K on plant mass) were adjusted for each crop. Also good agreement was generally obtained for plant weight and plant %K at harvest in less detailed experiments on 10 other crops. Values of the two 'crop' parameters for 12 of the crops were strongly correlated with one another suggesting that a single 'crop' parameter may be all that is required to define most inter-species differences in plant-K demand.
Simulations with the model indicate that, in central England, no response of 10 crops to K fertilizer would be likely on soils containing more than 170 mg of 1 M ammonium nitrate extractable-K/kg of soil and having clay contents of between 15 and 45%. Shortcomings of the model and opportunities for advance are discussed.
A simplified version of the model runs on the Internet at: http://www.qpais.co.uk/moda-djg/potass.htm