Na+ channel modulation and force-frequency relationship in human myocardium

Insect cell lines in culture are used for a variety of studies. In this laboratory imaginal disc cell lines have been established from primary cultures from third instar larvae, and used for a number of experiments. The effect of ageing on the morphology and physiology of Drosophila cell lines has received very little attention, although problems of genotypic or phenotypic changes in cell lines with age are recognized in other areas of animal cell culture. We tested our cell line Cl8+ for any difference in growth, morphology and response to 20-hydroxyecdysone (20HE) at different ages (passage numbers). The cells were found to multiply faster, adhere less firmly to the substrate and to lose the tendency to aggregate at higher passages. The response to 20HE in terms of cell numbers and induction of beta-galactosidase was similar at all passage numbers but morphological changes in hormone-treated cells were less obvious in the higher passages. Cell lines are likely to vary in the extent of ageing effects but workers are advised to be aware of the possibilities. We suggest the effects of age on cell lines should be established, and passage numbers noted in experimental reports.     

Intracranial and spinal dissemination of an ACTH secreting pituitary neoplasia. Case report and review of the literature

Smoking is associated with insulin resistance, dyslipidaemia and markers of the insulin resistance syndrome. This study investigated adipose tissue lipolysis in situ by subcutaneous microdialysis twice in 10 healthy, male smokers after smoking four cigarettes over 2 h and after the administration of an equal amount of nicotine given as nasal spray (NNS). Glucose and insulin levels, in situ lipolysis and adipose tissue blood flow were studied in the post-absorptive state and after a 75-g oral glucose tolerance test (OGTT). Post-absorptively, acute smoking and NNS increased neither subcutaneous adipose tissue glycerol production nor plasma free fatty acid (FFA) or glycerol levels. After the OGTT, plasma insulin and lactate levels were significantly higher after smoking, whereas FFA levels were higher after NNS. Normal smoking or the administration of a normal dose of NNS caused only minor metabolic changes. Thus, it does not seem likely that increased lipolysis is an important contributor to the dyslipidaemia seen in smokers.     

A novel method for elimination of line-current harmonics insingle-stage PFC switching regulators

This paper studies a particular single-stage power-factor-correction (PFC) switching regulator employing a discontinuous-conduction-mode (DCM) boost-input cell and a continuous-current-mode (CCM) forward output cell. Although this single-stage PFC regulator can provide a reasonably high power factor when its PFC stage is operating in discontinuous mode, substantial reduction in line-current harmonics is possible by applying a suitable frequency-modulation scheme. This paper derives a frequency-modulation scheme and proposes a practical implementation using a simple translinear analog circuit. A quantitative analysis on the total harmonic distortion (THD) of the line current when the circuit is subject to a limited range of frequency variations is presented along with some considerations for practical design. Experimental data obtained from a prototype confirms the effectiveness of the proposed frequency-modulation scheme. The proposed analog translinear circuit allows custom integrated circuit implementation, making it a viable low-cost solution to the elimination of line-current harmonics in switching regulators     

Fracture mechanics of oilseed rape pods

The basic theory of linear elastic fracture mechanics was applied to the fracture of pods from six genetic lines of oilseed rape (Brassica napus). An experiment was designed to allow the energetics of the fracture process to be accurately determined. The work of fracture, toughness and fracture toughness of five experimental varieties and one common commercial variety (Apex) were measured. The values for the toughness (0.006–0.271 kJ m-2) and fracture toughness (0.026–0.233 MN m-3/2) obtained from each line were distinct from each other but broadly similar to those of other brittle materials. The toughness and fracture toughness of Apex were approximately midway between the lowest and highest values measured. This result indicates that there is scope for improving the fracture resistance of oilseed rape crops so as to reduce seed loss before and during harvest. The approach described would be useful in selecting fracture-resistant genetic lines to help to develop such crops. This revised version was published online in November 2006 with corrections to the Cover Date.     

Electric field effects on roto-vibrational transitions of13CD3OH1

We used a Stark-Optoacoustic cell and hybrid waveguide resonators to perform an Infrared and Far Infrared Stark Spectroscopy study on some transitions of¹³CD₃OH. Different behaviours of the transitions in the presence of a d.c. electric field were observed. The Stark splittings of six FIR laser lines ranging from 34 to 136 MHz/kVcm^?1 were determined. The analysis of the behaviour of the IR and FIR transitions in the presence of the external electric fields gives important and exclusive information on the levels involved in the transitions.     

Neural networks,rational functions,and realization theory

The problem of parametrizing single hidden layer scalar neural networks with continuous activation functions is investigated. A connection is drawn between realization theory for linear dynamical systems, rational functions, and neural networks that appears to be new. A result of this connection is a general parametrization of such neural networks in terms of strictly proper rational functions. Some existence and uniqueness results are derived. Jordan decompositions are developed, which show how the general form can be expressed in terms of a sum of canonical second order sections. The parametrization may be useful for studying learning algorithms.This work was supported by the Australian Research Council, the Australian Telecommunications and Electronics Research Board, and the Boeing Commencai Aircraft Company (thanks to John Moore).     

Inhibiting and deactivating effects of water on the selective catalytic reduction of nitric oxide with ammonia over MnOx/Al2O3

The effect of water on the selective catalytic reduction (SCR) of nitric oxide with ammonia over alumina supported with 2–15 wt.-% manganese oxide was investigated in the temperature range 385–600 K, with the emphasis on the low side of this temperature window. Studies on the effect of 1–5 vol.-% water vapour on the SCR reaction rate and selectivity were combined with TPD experiments to reveal the influence of water on the adsorption of the single SCR reactants. It turned out that the activity decrease due to water addition can be divided into a reversible inhibition and an irreversible deactivation. Inhibition is caused by molecular adsorption of water. TPD studies showed that water can adsorb competitively with both ammonia and nitric oxide. Additional kinetic experiments revealed that adsorbed ammonia is present in excess on the catalyst surface, even in the presence of water. Reduced nitric oxide adsorption is responsible for the observed reversible decrease in the reaction rate; the fractional reaction order changes from 0.79 in the absence of water to 1.07 in its presence. Deactivation is probably due to the dissociative adsorption of water, resulting in the formation of additional surface hydroxyls. As the amount of surface hydroxyls formed is limited to a saturation level, the deactivating effect on the catalyst is limited too. The additional hydroxyls condense and desorb in the temperature range 525–775 K, resulting in a lower degree of deactivation at higher temperature. A high temperature treatment at 775 K results in a complete regeneration. The amount of surface hydroxyls formed per unit surface area decreases at increasing MnO_x-loading. The selectivity to the production of nitrogen is enhanced significantly by the presence of gas phase water.