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81.
The effects of an applied electric field on an ionic autocatalyticreaction with a quadratic rate law are considered, where thereacting species, A+ and B+, are present in a system which alsoincludes non-reacting species C- and D+. The conditions areestablished under which the general terms which describe theelectric field effects in the reaction-diffusion equations canbe simplified to those used in previous studies, where theseeffects are modelled by linear advection terms. The resultingequations are then studied in detail by first obtaining conditionsfor the existence of travelling waves of permanent form. Thisdiscussion shows that B, the ratio of the diffusion coefficientsof B+ and A+, is a critical parameter, with different formsof behaviour arising for B < 1 and B > 1. This analysisis augmented by obtaining solutions valid for large times andlarge values of (the dirnensionless applied field). Numericalsolutions of initial-value problems are obtained for a rangeof values of and B, guided by and interpreted through the analysispreviously obtained. These numerical integrations show the formationof reaction fronts, with the possibility of greatly increasedreaction rates caused by the applied electric field, as wellas propagating electrophoretic fronts in B+ being formed incases where a reaction front is also initiated. There is alsothe possibility of separate electrophoretic fronts in A+ andB+ being formed, which become increasingly separated as timeincreases with the reaction being completely inhibited. 相似文献
82.
Schubert A Holzmann R Hlavác S Kulessa R Niebur W Simon RS Lautridou P Lefèvre F Marqués M Matulewicz T Mittig W Ostendorf RW Roussel-Chomaz P Schutz Y Löhner H van Pol JH Siemssen RH Wilschut HW Ballester F Díaz J Marín A Martínez G Metag V Novotny R Wagner V Québert J 《Physical review letters》1994,72(11):1608-1611
83.
Reaction-diffusion systems with zero-flux Neumann boundariesare widely used to model various kinds of interaction in, forexample, the scientific fields of ecology, biology, chemistry,medicine and industry. The physical systems within these fieldsare often known to be (conditionally or unconditionally) resilientwith respect to shocks, disturbances or catastrophies in theimmediate environment. In order to be good mathematical modelsof such situations the reaction-diffusion systems must havethe same resilient or asymptotic behaviour as that of the physicalsituation. Three fundamentally different kinds of reaction termsare usually distinguished according to the entry signs of thereaction Jacobian: mutualism, mixed (predator-prey) interactionand competition. The asymptotic stability (in the Poincarésense) of mutualistic systems has already been studied extensively,but the results cannot be generalized (globally) to the othertwo fundamental types, which are not order-preserving. A partial(local) generalization is, however given here for these twotypes, involving simple Jacobian inequalities and knowledge(often prompted by the underlying physical situation) of invariantsets in solution space. The return time of resilient systemsand the approach rate of asymptotically stable solutions arealso estimated. 相似文献
84.
V. Meyer S.N. Bagayev P.E.G. Baird P. Bakule M.G. Boshier A. Breitrück S.L. Cornish S. Dychkov G.H. Eaton A. Grossmann D. Hübl V.W. Hughes K. Jungmann I.C. Lane Yi Wei Liu D. Lucas Y. Matyugin J. Merkel G. zu Putlitz I. Reinhard P.G.H. Sandars R. Santra P. Schmidt C.A. Scott W.T. Toner M. Towrie K. Träger L. Willmann V. Yakhontov 《Hyperfine Interactions》2000,127(1-4):197-200
The 1s–2s energy interval in the muonium (μ+e−) atom has been measured by Doppler free two photon laser spectroscopy. A value of 2455528941.0(9.8) MHz has been obtained
in good agreement with quantum electrodynamics (QED). The muon-electron mass ratio can be extracted and is found to be 206.76838(17).
The measurement may also be interpreted as a determination of the muon-electron charge ratio as -1- 1.1(2.1)· 10−9. Corresponding measurements in deuterium using the same experimental setup confirmed the validity of the applied analysis
procedure.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
85.
86.
Background
The precise form of the light response of human cone photoreceptors in vivo has not been established with certainty. To investigate the response shape we compare the predictions of a recent model of transduction in primate cone photoreceptors with measurements extracted from human cones using the paired-flash electroretinogram method. As a check, we also compare the predictions with previous single-cell measurements of ground squirrel cone responses. 相似文献87.
The article presents a tree search algorithm (TRSA) for the strip packing problem in two and three dimensions with guillotine cutting constraint. In the 3D-SPP a set of rectangular items (boxes) and a container with fixed width and height but variable length are given. An arrangement of all boxes within the container has to be determined so that the required length is minimised. The 2D-SPP is analogously defined. The proposed TRSA is based on a tree search algorithm for the container loading problem by Fanslau and Bortfeldt (INFORMS J. Comput. 22:222?C235, 2010). The TRSA generates guillotine packing patterns throughout. In a comparison with all recently proposed 3D-SPP methods the TRSA performs very competitive. Fine results are also achieved for the 2D-SPP. 相似文献
88.
Lorenz Willmann Klaus Jungmann Cornelis J. G. Onderwater Rob G. E. Timmermans Hans W. Wilschut 《Hyperfine Interactions》2012,211(1-3):39-43
Discrete symmetries tested in high precision atomic physics experiments provide guidance to model building beyond the Standard Model (SM). Here experimental opportunities arise for searches for permanent electric dipole moments (EDMs) and measurements of atomic parity violation (APV). Heavy atoms are favorable for such experiments since symmetry violating effects in atoms increase faster than the third power of the nuclear charge Z. Of special interest are isotopes of the heavy alkaline earth element radium (Z=88) since they offer large enhancement factors for EDMs and provide a new experimental road towards high precision measurements of atomic parity violation. These opportunities are exploited at the TRIμP facility at KVI, Groningen. 相似文献
89.
Abbott T Akiba Y Alburger D Beavis D Betts RR Birstein L Bloomer MA Bond PD Chasman C Chu YY Cole BA Costales JB Crawford HJ Cumming JB Debbe R Duek E Engelage J Fung SY Grodzins L Gushue S Hamagaki H Hansen O Hayashi S Homma S Huang HZ Ikeda Y Katcoff S Kaufman S Kimura K Kitamura K Kurita K Ledoux RJ Levine MJ Miake Y Morse RJ Nagamiya S Olness J Parsons CG Remsberg LP Sarabura M Shor A Stankus P Steadman SG Stephans GS Sugitate T Tannenbaum MJ Torikoshi M van Dijk JH Videbaek F Vient M 《Physical review letters》1990,64(8):847-850
90.
Verheijen JC Deiman BA Yeheskiely E van Der Marel GA van Boom JH 《Angewandte Chemie (International ed. in English)》2000,39(2):369-372
The introduction of a urea bond linking a protected diethylenetriamine (DETA) unit and the terminal amino group of a resin-bound peptide nucleic acid (PNA) decamer gave access to a PNA - DETA adduct (shown here), which hydrolyzed the target 25-mer RNA rapidly and sequence specifically. 相似文献