Survey of Major Points of Interest About Reactions of Cholinesterases

Three areas of current interest and activity in the study of the cholinesterases have been chosen for comment: Aging of phosphorylated cholinesterases. Recent work indicates that aging (loss of groups attached to the phosphorus) can be brought about by at least two mechanisms. It now seems probable that aging is a more general reaction and is not restricted to the cholinesterases. Inhibition by excess substrate and other effects. An attempt has been made to bring together into one model experimental results from a number of different approaches. These include acceleration of hydrolysis and inhibition by quaternary ammonium compounds, differences in pH-rate profiles for various substrates and various inhibitors, substrate inhibition and inhibition by haloxon. Molecular weight of acetylcholinesterase in membranes. A recent paper indicating that acetylcholinesterase in membranes is monomeric is discussed

Noise-enabled precision measurements of a Duffing nanomechanical resonator

We report quantitative experimental measurements of the nonlinear response of a radiofrequency mechanical resonator, with very high quality factor, driven by a large swept-frequency force. We directly measure the noise-free transition dynamics between the two basins of attraction that appear in the nonlinear regime, and find good agreement with those predicted by the one-dimensional Duffing equation of motion. We then measure the response of the transition rates to controlled levels of white noise, and extract the activation energy from each basin. The measurements of the noise-induced transitions allow us to obtain precise values for the critical frequencies, the natural resonance frequency, and the cubic nonlinear parameter in the Duffing oscillator, with direct applications to high sensitivity parametric sensors based on these resonators.Comment: 5 pages, 5 figure

ABSORPTIOMETRIC DETERMINATION OF MERCURY Organo-tin -Dithizone Complexes The Colorimetric Determination of Diethyltin and Triethyltin Compounds

It has been demonstrated that some organo-tin compounds react with dithizone. The absorption maximum for the diethyltin -dithizone complex, after being shaken with 10 per cent. trichloroacetic acid, is a t 510 mp, whereas triethyltin does not react under these conditions. In the presence of borate buffer of pH 8.4, diethyltin and triethyltin compounds produce with dithizone absorption maxima a t 485 and 440 mp, respectively. At 510 m p the triethyltin -dithizone complex and dithizone have the same absorption. Based upon these findings and their distribution between chloroform and aqueous media, a method is described for the separation and determination of diethyltin and triethyltin compounds. Interference from other metals is avoided by the use of ethylenediaminetetra-acetic acid. RECENTLY interest has been shown in the biological activity of organo-tin compounds,1 ,2 after reports of their potential use as fungicides,3 as clearing agents in plastics and for the treatment of boils in France.4 A method was required for the determination of the dialkyltin and trialkyltin compounds and for estimating mixtures of these compounds. Although diphenylthiocarbazone (dithizone) is a well known reagent for detecting small amounts of metals, little use has been made of its reactivity with organo-metallic compounds. Miller, Polley and Gould5 and later Miller and Polley6 reported a method for determining mixtures of ethylmercuric and phenylmercuric compounds by using dithizone and stated that several other organo-mercuric compounds reacted with this reagent. Webb, Bhatia, Convin and Sharp7 also published analytical data on the reaction products of dithizone and organo-mercury compounds. In this paper it is shown that dithizone reacts with organo-tin compounds, and a method for the qualitative and quantitative differentiation of mixtures of triethyltin and diethyltin compounds is described. EXPERIMENTAL All optical measurements were made with a Unicam SP600 spectrophotometer. A preliminary investigation showed that , when a solution of diethyltin dichloride was shaken with a chloroform solution of dithizone in the presence of aqueous 10 per cent. trichloroacetic acid, a red colour was produced. Tetraethyltin and triethyltin sulphate did not react under these conditions. On the other hand, when shaken with borate buffer of pH 8-4, triethyltin sulphate gave a yellow colour and diethyltin dichloride an orange colour. Under these conditions neither tetraethyltin, monoethyltin nor stannic chloride produced any change of colour

Siren songs or path to salvation? Interpreting the visions of web technology at a UK regional newspaper in crisis, 2006-11

A 5-year case study of an established regional newspaper in Britain investigates journalists about their perceptions of convergence in digital technologies. This research is the first ethnographic longitudinal case study of a UK regional newspaper. Although conforming to some trends observed in the wider field of scholarship, the analysis adds to skepticism about any linear or directional views of innovation and adoption: the Northern Echo newspaper journalists were observed to have revised their opinions of optimum Web practices, and sometimes radically reversed policies. Technology is seen in the period as a fluid, amorphous entity. Central corporate authority appeared to diminish in the period as part of a wider reduction in formalism. Questioning functionalist notions of the market, the study suggests cause and effect models of change are often subverted by contradictory perceptions of particular actions. Meanwhile, during technological evolution, the ‘professional imagination’ can be understood as strongly reflecting the parent print culture and its routines, despite pioneering a new convergence partnership with an independent television company

Wind assessment for micro wind turbines in an urban environment

Wind flow in urban environments could be seen as a potential source of energy. This form of energy could be exploited by means of micro wind turbines placed along the existing infrastructures. To test this, an outdoor campaign was organised, which recorded the wind characteristics at different locations around a highway noise barrier in Delft, the Netherlands. The real-time data set was validated with a two-dimensional Computational Fluid Dynamics study. Both the influence of the high turbulence and the inflow angle on the positioning of the micro wind turbines are assessed for the case of perpendicular flow towards the plane of the noise barrier. Results indicated that integrating micro wind turbines with the noise barriers proves advantageous due to the flow velocity increment downstream. Lastly, a noise assessment was conducted in order to determine the optimal spacing between micro wind turbines, which impacts its social acceptance

The apparatus composition and architecture of Erismodus quadridactylus and the implications for element homology in prioniodinin conodonts

The apparatus composition and architecture of prioniodinin conodonts is poorly understood, largely because few prioniodinin taxa are represented by articulated oral feeding apparatuses (natural assemblages) in the fossil record, but also due to the highly variable gradational morphology of their constituent elements that makes apparatus reconstruction problematic. We describe here a natural assemblage of Erismodus quadridactylus (Stauffer), a prioniodinin, from the Sandbian (Late Ordovician) of North Dakota, USA. The assemblage demonstrates that the apparatus architecture of Erismodus is similar to those of late Palaeozoic prioniodinins namely, Kladognathus Rexroad and Hibbardella Bassler, but also has similarities with ozarkodinin apparatuses. In addition, there is evidence to suggest that E. quadridactylus shares topological similarities to balognathid architecture, with respect to the position of its inferred P elements. The apparatus composition and architecture presented here indicate that, at least with respect to the M–S array, an ‘ozarkodinin‐type’ bauplan is probably more widely representative across prioniodontids. The assemblage demonstrates that element morphotypes traditionally considered to lie within the S array are M elements, whereas others traditionally interpreted as P elements are found in the S array. These observations are used as a basis for refining concepts of element homology among prioniodinin conodonts and their closest relatives

An exploratory randomised controlled trial of a premises-level intervention to reduce alcohol-related harm including violence in the United Kingdom

<b>Background</b><p></p> To assess the feasibility of a randomised controlled trial of a licensed premises intervention to reduce severe intoxication and disorder; to establish effect sizes and identify appropriate approaches to the development and maintenance of a rigorous research design and intervention implementation.<p></p> <b>Methods</b><p></p> An exploratory two-armed parallel randomised controlled trial with a nested process evaluation. An audit of risk factors and a tailored action plan for high risk premises, with three month follow up audit and feedback. Thirty-two premises that had experienced at least one assault in the year prior to the intervention were recruited, match paired and randomly allocated to control or intervention group. Police violence data and data from a street survey of study premises’ customers, including measures of breath alcohol concentration and surveyor rated customer intoxication, were used to assess effect sizes for a future definitive trial. A nested process evaluation explored implementation barriers and the fidelity of the intervention with key stakeholders and senior staff in intervention premises using semi-structured interviews.<p></p> <b>Results</b><p></p> The process evaluation indicated implementation barriers and low fidelity, with a reluctance to implement the intervention and to submit to a formal risk audit. Power calculations suggest the intervention effect on violence and subjective intoxication would be raised to significance with a study size of 517 premises.<p></p> <b>Conclusions</b><p></p> It is methodologically feasible to conduct randomised controlled trials where licensed premises are the unit of allocation. However, lack of enthusiasm in senior premises staff indicates the need for intervention enforcement, rather than voluntary agreements, and on-going strategies to promote sustainability