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61.
F. H. Clarke Yu. S. Ledyaev M. L. Radulescu 《Journal of Dynamical and Control Systems》1997,3(4):493-518
Consider a mappingF from a Hilbert spaceH to the subsets ofH, which is upper semicontinuous/Lipschitz, has nonconvex, noncompact values, and satisfies a linear growth condition. We give
the first necessary and sufficient conditions in this general setting for a subsetS ofH to be approximately weakly/strongly invariant with respect to approximate solutions of the differential inclusion
. The conditions are given in terms of the lower/upper Hamiltonians corresponding toF and involve nonsmooth analysis elements and techniques. The concept of approximate invariance generalizes the well-known
concept of invariance and in turn relies on the notion of an ∈-trajectory corresponding to a differential inclusion.
Dedicated to Professor R. V. Gamkrelidze
The first and the third authors are supported in part by the Natural Sciences and Engineering Research Council of Canada and
Le Fonds FCAR du Québec.
The second author is visiting Rutgers University. Supported in part by the Russian Foundation for Fundamental Research, Grant
96-01-00219, by the Natural Sciences and Engineering Research Council of Canada, Le Fonds FCAR du Québec, and by the Rutgers
Center for Systems and Control (SYCON). 相似文献
62.
Benthic invertebrate communities were examined in Compensation Creek, a man‐made stream in south‐central Newfoundland, Canada. Samples taken in September 2006 and September 2007 from large woody debris (LWD) were compared with samples from benthic environments to determine whether LWD supported a more diverse and abundant invertebrate community. Benthic habitats in a nearby natural stream were also sampled. Taxa composition was similar between the man‐made and the natural stream, highlighting successful colonization for the majority of taxa. Within Compensation Creek, taxa richness was higher in benthic habitats than on LWD, likely influenced by the successional age of the stream and surrounding habitat. The more complex benthic substrate provided refugia and allowed for the accumulation of fine detritus as a food source. Scrapers were almost completely absent from LWD and collector‐gatherer abundance was greater in the benthos. Collector‐filterer abundance was more than six times greater near the pond outflow than farther downstream when discharge was high, but abundances were almost equal when discharge was reduced. Riparian vegetation has not fully established around the man‐made stream, whereas it is overhanging and extensive at the natural stream, leading to more leaf‐litter input for shredders. As the morphology of Compensation Creek changes, the invertebrate community will continue to develop and likely increase utilization of accumulated detritus at LWD. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
63.
T. E. Kavanagh S. R. Steward R. P. Hildebrand B. J. Clarke F. J. Meeker 《Journal of the Institute of Brewing》1975,81(4):322-327
Dimethyl sulphide formation in malt occurs primarily during the kilning process, and is significantly dependent upon the maximum kilning temperature. During mashing a considerable fraction of the dimethyl sulphide of malt is transferred to the wort. Since this is not always completely removed by the wort boiling process, the remaining dimethyl sulphide, although decreased during fermentation, may be sufficient to impart a noticeable dimethyl sulphide aroma to the finished beer. 相似文献
64.
Tracey M. Clarke Amy M. Ballantyne Jenny Nelson Donal D. C. Bradley James R. Durrant 《Advanced functional materials》2008,18(24):4029-4035
The function of organic solar cells is based upon charge photogeneration at donor/acceptor heterojunctions. In this paper, the origin of the improvement in short circuit current of poly(3‐hexylthiophene)/6,6‐phenyl C61‐butyric acid methyl ester (P3HT/PCBM) solar cells with thermal annealing is examined. Transient absorption spectroscopy is employed to demonstrate that thermal annealing results in an approximate two‐fold increase in the yield of dissociated charges. The enhanced charge generation is correlated with a decrease in P3HT's ionization potential upon thermal annealing. These observations are in excellent quantitative agreement with a model in which efficient dissociation of the bound radical pair into free charges is dependent upon the bound radical state being thermally hot when initially generated, enabling it to overcome its coulombic binding energy. These observations provide strong evidence that the lowest unoccupied molecular orbital (LUMO) level offset of annealed P3HT/PCBM blends may be only just sufficient to drive efficient charge generation in polythiophene‐based solar cells. This has important implications for current strategies to optimize organic photovoltaic device performance based upon the development of smaller optical bandgap polymers. 相似文献
65.
Kennard Betsy D.; Clarke Greg N.; Weersing V. Robin; Asarnow Joan Rosenbaum; Shamseddeen Wael; Porta Giovanna; Berk Michele; Hughes Jennifer L.; Spirito Anthony; Emslie Graham J.; Keller Martin B.; Wagner Karen D.; Brent David A. 《Canadian Metallurgical Quarterly》2009,77(6):1033
In this report, we conducted a secondary analysis of the Treatment of SSRI-Resistant Depression in Adolescents (TORDIA) study to explore the impact of specific cognitive–behavioral therapy (CBT) treatment components on outcome. In TORDIA, 334 youths (ages 12 to 18 years) with major depressive disorder who had failed to respond to an adequate course of selective serotonin reuptake inhibitor (SSRI) medication were randomized to a medication switch (either to an alternative SSRI or venlafaxine) with or without 12 weeks of adjunctive CBT. Participants who had more than 9 CBT sessions were 2.5 times more likely to have adequate treatment response than those who had 9 or fewer sessions. CBT participants who received problem-solving and social skills treatment components, controlling for number of sessions and other confounding variables, were 2.3 and 2.6 times, respectively, more likely to have a positive response. These preliminary findings underscore the importance of receiving an adequate number of sessions to attain an adequate clinical response. Finally, social skills and problem solving may be active elements in CBT for adolescent depression and should be considered in treatment by those working with seriously depressed youths. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
66.
Within 12 months of the discovery of X rays in 1895, papers appeared in the literature reporting adverse effects from high exposure. In 1925, the first International Congress of Radiology, held in London, considered the need for a protection committee, which it established at its second congress in Stockholm in 1928. This paper celebrates the 80th anniversary of ICRP by tracing the history of the development of its policies, and identifying a few of the personalities involved from its inception up to the modern era. The paper follows the progress from the early controls on worker doses to avoid deterministic effects, through the identification of stochastic effects, to the concerns about public exposure and increasing stochastic risk estimates. The key features of the recommendations made by ICRP from 1928 up to the most recent in 2007 are identified. 相似文献
67.
LL Bestervelt JA Pitt CJ Nolan Y Cai DW Piper JA Dybowski GA Dayharsh WN Piper 《Canadian Metallurgical Quarterly》1998,44(2):107-115
Pharmacological effects of acute treatment with venlafaxine (VEN), a clinically active antidepressant [a noradrenaline (NA) and 5-hydroxytryptamine (5-HT) reuptake inhibitor without any affinity for neurotransmitter receptors] were studied in mice and rats. VEN inhibited the reserpine- or apomorphine-induced hypothermia and enhanced the L-5-HTP-induced head twitches in mice. It reduced the immobility time in Porsolt's test in mice and rats, but either did not change the locomotor activity (mice) or decreased it (rats). VEN reduced the locomotor hyperactivity induced by amphetamine (AMP), apomorphine (APO) and quinpirole (QUI), as well as the APO-induced stereotypy; the stereotypy induced by AMP in rats was prolonged. VEN neither changed the clonidine-induced aggressiveness in mice nor the behavioral syndrome induced by oxotremorine in rats. The obtained results indicate that VEN, given acutely, shows a pharmacological profile similar to that of tricyclic NA and 5-HT reuptake inhibitors. In contrast to the antidepressants mentioned above, VEN does not exhibit an alpha 1-adrenolytic or a cholinolytic activity (in vivo tests). 相似文献
68.
A new preprocessing technique which removes unwanted notches and random noise generated by electronic scanners is presented. Using a 3 element by 3 element mask, the central picture element is altered from black to white, or vice versa, if the surrounding elements correspond to a predetermined pattern. A significant improvement in both subjective image quality and coding efficiency is observed. 相似文献
69.
A simple regulator for stabilizing the temperature of a liquid (4)He bath near 4.2 K is described. The device controls the pressure of the (4)He gas, and achieves a stability of +/-50 muK for the hold-time of the cryostat. 相似文献
70.
R.J. Clarke 《Food chemistry》1979,4(1):81-96
The author describes the particular technical features of coffee standards used commercially and/or legislatively. Existing national standards on green coffee and their harmonisation of terminology, sampling and test method are described and discussed. Comparisons are made of the various legislative standards of different countries with respect to instant coffee and their harmonisation within the EEC member countries. Roasted coffee is considered to a lesser extent as it is not an important element in the world trade for coffee. The role of various international organisations in standardisation is described. It is emphasised that the flavour of coffee is not amenable to international standardisation. 相似文献