The Cramér-Rao estimation error lower bound computation for deterministic nonlinear systems

For continuous-time nonlinear deterministic system models with discrete nonlinear measurements in additive Ganssian white noise, the extended Kalman filter (EKF) convariance propagation equations linearized about the true unknown trajectory provide the Cramér-Rao lower bound to the estimation error covariance matrix. A useful application is establishing the optimum filter performance for a given nonlinear estimation problem by developing a simulation of the nonlinear system and an EKF linearized about the true trajectory.     

Growth hormone, insulin and sugar in the blood plasma of bulls. Interrelated diurnal variations

Plasma growth hormone (GH) of eight young, sexually mature, pedigree bulls, observed at hourly intervals, varied during the day in a manner indicating intermittent secretion in peaks or bursts. The diurnal GH averages were about 10 ng/ml. GH averages for 2-3 h intervals showed minima following or during the periods of morning and afternoon feeding. A third minimum occurred between 10 and 12 p.m. Peak activity, estimated by the frequency of GH values greater than 10 ng/ml was significantly reduced during two of these low-GH-periods (afternoon and late night). The minima in GH followed after (morning) or coincided with (afternoon) maxima in plasma insulin (two materials, GH/insulin, 11 a. m.-10 p.m.: r=-0.31 and -3.34, P less than 0.01). This means that the two hormones behaved after food intake much in the same ways as in man in spite of the fact that plasma sugar decreased after feeding (GH/sugar, 11 a.m.-10 p.m.: r=0.27, two materials combined, P less than 0.001). The possibility of GH involvement in the hour-to-hour metabolic homoeostasis of the animals is discussed.     

The influence of molybdenum concentration on the magnetic permeability and kinetics of order formation in molybdenum permalloys

The initial magnetic permeabilities of molybdenum permalloys with a range of molybdenum concentrations have been measured as a function of isothermal annealing time in the temperature range 400 to 600° C. Annealing in the range from 400 to 460° C produces short-range ordering, leading to a maximum initial permeability when the magnetostriction is reduced to zero. From 460 to approximately 490 to 500° C it is suggested that microdomains of long-range order nucleate and grow in a short-range ordered matrix and these reduce the maximum initial permeability which can be obtained. Above about 490 to 500° C, long-range order does not form, but equilibrium values of short-range order are too small to produce initial magnetic permeabilities as large as in the lower temperature region. The rate of short-range order formation has been found to increase sharply at molybdenum concentrations of about 4 wt % (2.5 at. %) and the activation energy for short-range order formation falls sharply from about 180 kJ mol^–1 to 140 kJ mol^–1 at this molybdenum concentration. It is thought that different ordered structures and mechanisms of ordering occur below and above 4 wt% molybdenum. Quenching experiments suggest that quenched-in vacancies can increase the rates of short-range order production.     

Electromagnetic syringe

A device is described which can be used as a "hyperdermic syringe" to inject electromagnetic energy into deep-lying tissues.     

Evaporative analyser as a mass detector in the size-exclusion chromatography of coal extracts

The applicability of the evaporative analyser in the size-exclusion chromatography (SEC) of coal derivatives has been explored. The detector, in which the intensity is measured for the light scattered from the finely divided solute particles resulting from evaporation of droplets of chromatographic eluate, is mass responsive, sensitive, and linear for both narrow and gross coal-extract fractions. For molecular masses above 300 the mass response is almost uniform, and there are considerable advantages over the detectors commonly used in SEC. Application to lower molecular mass coal materials is limited by the evaporation of solute along with solvent in the detector.     

Aircraft keyboard ergonomics: a review

The increasing use of complex digital avionics systems has resulted in the aircraft pilot making ever greater use of keyboards. The designer has comparatively little coherent information or guidance to help him select the optimal physical and functional characteristics of the keyboard, but current technology gives him a very wide choice. Much of the current literature relates to studies based on static ground environments and, although there is some evidence derived from studies of aircraft, the majority of the ergonomics data relevant to keyboard design is not easily generalized to the airborne environment. A review of the current military standards underlines this as they are brief and they are not always rigidly adhered to in practice. The factors which are likely to affect keying performance are discussed and the state of ergonomics knowledge in the area reviewed.     

CERAMIC CARBIDE POWDER SYNTHESIS IN A NON-TRANSFERRED ARC PLASMA FLOW REACTOR

A method for the synthesis of fine, pure ceramic carbide powders such as silicon carbide, boron carbide and titanium carbide has been developed involving the thermal dissociation of silica, boron oxide or titanium oxide and methane in a thermal plasma, followed by the formation of the carbides in flight and rapid quenching. A non-transferred arc thermal plasma reactor has been designed, engineered, constructed and operated for this synthesis. The powders have been characterized chemically and physically. Thermodynamic calculations were performed to identify the appropriate experimental conditions and confirm the interpretations of the observed experimental results. A reaction mechanism is proposed based upon the experimental observations and results     

Effect of suramin on p34cdc2 kinase in vitro and in extracts from human H69 cells: evidence for a double mechanism of action

We examined the effect of suramin, an anticancer agent and a functional analog of naturally occuring glycosaminoglycans, on p34cdc2 kinase. We find that suramin strongly inhibits the catalytic activity of purified p34cdc2 kinase (IC50 approximately 4 microM), whereas it only weakly inhibits the p13-agarose precipitated kinase activity from nuclear and cytoplasmic extracts of the asynchronous H69 human small cell lung cancer cells. We also find that the tyrosine phosphorylation of p34cdc2 kinase in the nuclear extract is increased about twice when the extracts are preincubated with 50 microM of suramin prior to the p13-agarose precipitation. We propose that this increase might result from the inhibitory effect of suramin towards p34cdc2-specific tyrosine phosphatases. These results suggest both a direct and an indirect effect of suramin on p34cdc2 kinase. We also find that heparin is a potent inhibitor of purified cdc2 kinase (IC50 approximately 3.5 micrograms/ml). Therefore, glycosaminoglycans might be physiological regulators of p34cdc2 kinase in vivo.