101 resultados para Reduction of Time


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This article considers the paradox of improvisation as a gift out of time, which is completely in tune with time, subject to time. It does so through an alignment of Jacques Derrida’s philosophy and the poetic writings of Hélène Cixous. Ever mindful of the possible impossibility of improvisation in Derrida’s work, improvisation here is given over to Cixous, to the side of life, and is theorised as a type of ‘feminine writing’, as an inventive strategy that calls forth the unknown other and dreams of a gift in life that is out of time.

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The voltammetry for the reduction of oxygen at a microdisk electrode is reported in six commonly used RTILs: [C(4)mim][NTf2], [C(4)mpyrr][NTf2], [C(4)dmim][NTf2], [C(4)mim][BF4], [C(4)mim][PF6], and [N-6.2.2.2][NTf2], where [C(4)mim](+) is 1-butyl-3-methylimidazolium, [NTf2](-) is bis(trifluoromethanesulfonyl)imide, [C(4)mpyrr](+) is N-butyl-N-methylpyrrolidinium, [C(4)dmim](+) is 1-butyl-2,3-methylimidazolium, [BF4](-) is tetrafluoroborate, [PF6](-) is hexafluorophosphate, and [N-6.2.2.2](+) is n-hexyltriethylammonium at varying scan rates (50-4000 mV s(-1)) and temperatures (293-318 K). Diffusion coefficients, D, of oxygen are deduced at each temperature from potential-step chronoamperometry, and diffusional activation energies are calculated. Oxygen solubilities are also reported as a function of temperature. In the six ionic liquids, the Stokes-Einstein relationship (D proportional to eta(-1)) was found to apply only very approximately for oxygen. This is considered in relationship to the behavior of other diverse solutes in RTILs.

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For the purpose of equalisation of rapidly time variant multipath channels, we derive a novel adaptive algorithm, the amplitude banded LMS (ABLMS); which implements a nonlinear adaptation based on a coefficient matrix. Then we develop the: ABLMS algorithm as the adaptation procedure for a linear transversal equaliser (LTE) and a decision feedback equaliser (DFE) where a parallel adaptation scheme is deployed. Computer simulations demonstrate that with a small increase of computational complexity, the ABLMS based parallel equalisers provide a significant improvement related to the conventional LMS DFE and the LMS LTE in the case of a second order Markov communication channel model.

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Surface plasmon resonance (SPR) based biosensor technology has been widely used in life science research for many applications. While the advantages of speed, ruggedness, versatility, sensitivity and reproducibility are often quoted, many researchers have experienced severe problem of non-specific binding (NSB) to chip surfaces when performing analysis of biological samples Such as bovine serum. Using the direct measurement of the bovine protein leptin, present in bovine serum samples as a model, a unique buffering system has been developed and optimised which was able to significantly reduce the non-specific interactions of bovine serum components with the carboxymethyl dextran chip (CM5) surface on a Biacore SPR The developed NSB buffering system comprised of HBS-EP buffer, containing 0.5 M NaCl, 0.005% CM-dextran pH 9.0. An average NSB reduction (n = 20) of 85.9% and 87.3% was found on an unmodified CM5 surface and a CM5 with bovine leptin immobilised on the chip surface, respectively. A reduction in NSB of up to 94% was observed on both surfaces. The concentration of the constitutive components and pH of the buffer were crucial in achieving this outcome. (C) 2008 Elsevier B.V. All rights reserved.

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Cantello, Barrier C. C.; Eggleston, Drake S.; Haigh, David; Haltiwanger, R. Curtis; Heath, Catherine M.; Hindley, Richard M.; Jennings, Keith R.; Sime, John T.; Woroniecki, Stefan R. SmithKline Beecham Pharmaceuticals, Surrey, UK. Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1994), (22), 3319-24. Publisher: Royal Society of Chemistry, CODEN: JCPRB4 ISSN: 0300-922X. Journal written in English. CAN 122:105736 AN 1995:237497 CAPLUS (Copyright (C) 2009 ACS on SciFinder (R)) Abstract A novel biotransformation system for the redn. of carbon-carbon double bonds in 5-benzylidenethiazolidine-2,4-diones to give the corresponding 5-benzylthiazolidine-1,4-diones, using whole cells of red yeasts, is described. These reduced compds., which are recovered in good yield, are of potential use in the treatment of non-insulin dependent diabetes mellitus. The mild reaction conditions developed allow redn. of 5-benzylidenethiazolidine-2,4-diones contg. other functionalities which are not compatible with alternative redn. methods. The biocatalytic redn. is enantioselective and the synthesis of R-(+)-5-(4-{2-[methyl(2-pyridyl)amino]ethoxy}benzyl)thiazolidine-2,4-dione by Rhodotorula rubra CBS 6469 and structure confirmation by X-ray crystallog. is detailed. Optimization of reaction conditions (including immobilization) for these whole cell redn. system is described.

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The reduction of guanine was studied by microelectrode voltammetry in the room temperature ionic liquids (RTILs) N-hexyltriethylammonium his (trifluoromethanesulfonyl) imide [N-6.2.2.2][N(Tf)(2)], 1-butyl-3-methylimidazolium hexafluorosphosphate [C(4)mim] [PF6], N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide [C(4)mpyrr][N(Tf)(2)], 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C-4mim][N(TF)(2)], N-butyl-N-methyl-pyrrolidinium dicyanamide [C(4)mpyrr][N(NC)(2)] and tris(P-hexyl)-tetradecylphosphonium trifluorotris(pentafluoroethyl)phosphate [P-14,P-6,(6,6)][FAP] on a platinum microelectrode. In [N-6,N-2,N-2,N-2][NTf2] and [P-14,P-6,P-6.6][FAP], but not in the other ionic liquids studied, guanine reduction involves a one-electron, diffusion-controlled process at very negative potential to produce an unstable radical anion. which is thought to undergo a dimerization reaction, probably after proton abstraction from the cation of the ionic liquid. The rate of this subsequent reaction depends on the nature of the ionic liquid, and it is faster in the ionic liquid [P-14,P-6,P-6.6[FAP], in which the formation of the resulting dimer can be voltammetrically monitored at less negative potentials than required for the reduction of the parent molecule. Adenine showed similar behaviour to guanine but the pyrimidines thymine and cytosine did not; thymine was not reduced at potentials less negative than required for solvent (RTIL) decomposition while only a poorly defined wave was seen for cytosine. The possibility for proton abstraction from the cation in [N-6,N-2,N-2,N-2],[NTF2] and [P-14,P-6,P-6.6][FAP] is noted and this is thought to aid the electrochemical dimerization process. The resulting rapid reaction is thought to shift the reduction potentials for guanine and adenine to lower values than observed in RTILs where the scope for proton abstraction is not present. Such shifts are characteristic of so-called EC processes where reversible electron transfer is followed by a chemical reaction. (C) 2009 Elsevier B.V. All rights reserved.

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OBJECTIVE: To clarify whether the increase in childhood type 1 diabetes is mirrored by a decrease in older age-groups, resulting in younger age at diagnosis.
RESEARCH DESIGN AND METHODS: We used data from two prospective research registers, the Swedish Childhood Diabetes Register, which included case subjects aged 0-14.9 years at diagnosis, and the Diabetes in Sweden Study, which included case subjects aged 15-34.9 years at diagnosis, covering birth cohorts between 1948 and 2007. The total database included 20,249 individuals with diabetes diagnosed between 1983 and 2007. Incidence rates over time were analyzed using Poisson regression models.
RESULTS: The overall yearly incidence rose to a peak of 42.3 per 100,000 person-years in male subjects aged 10-14 years and to a peak of 37.1 per 100,000 person-years in female subjects aged 5-9 years and decreased thereafter. There was a significant increase by calendar year in both sexes in the three age-groups <15 years; however, there were significant decreases in the older age-groups (25- to 29-years and 30- to 34-years age-groups). Poisson regression analyses showed that a cohort effect seemed to dominate over a time-period effect.
CONCLUSIONS: Twenty-five years of prospective nationwide incidence registration demonstrates a clear shift to younger age at onset rather than a uniform increase in incidence rates across all age-groups. The dominance of cohort effects over period effects suggests that exposures affecting young children may be responsible for the increasing incidence in the younger age-groups.