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91.
On the Spectra of Striped Sign Patterns 总被引:4,自引:0,他引:4
J. J. McDonald D. D. Olesky M. J. Tsatsomeros P. van den Driessche 《Linear and Multilinear Algebra》2003,51(1):39-48
Sign patterns consisting of some positive and some negative columns, with at least one of each kind, are shown to allow any self-conjugate spectrum, and thus to allow any inertia. In the case of the n ×n sign pattern with all columns positive, given any self-conjugate multiset consisting of n -1 complex numbers supplemented by a sufficiently large positive number, it is shown how to construct a positive normal matrix whose spectrum is this multiset. Thus, the positive sign pattern allows any inertia with at least one positive eigenvalue. 相似文献
92.
O. Häusser T.K. Alexander D.L. Disdier A.J. Ferguson A.B. McDonald I.S. Towner 《Nuclear Physics A》1973,216(3):617-628
The α-decay of several unbound levels in 20Ne has been studied by 16O(α, α) elastic and inelastic scattering. A narrow resonance, Γc.m. = 13±4 eV, with Jπ = 5? was found at and is associated with the lowest K = 2? quasirotational band. Several new, narrow resonances were found between Ex = 16.0?18.4 MeV. Reduced α-decay widths have been obtained for the lowest K = 0+, 2? and 0?bands. For states described predominantly by the (8, 2) representation of SU(3) we note a reduction of the reduced widths with increasing spin. Reduced widths of positive parity bands are reviewed. 相似文献
93.
P. Darriulat P. Dittmann K. Eggert M. Holder K.T. McDonald T. Modis F.L. Navarria A. Seiden J. Strauss G. Vesztergombi E.G.H. Williams 《Nuclear Physics B》1976,107(3):429-456
We present a study of the final state structure in proton-proton collisions (√s = 53 GeV) where a large transverse momentum π0 (pt > 2 GeV/c) is produced at an angle of 90°. Charged secondaries have been detected and momentum analysed in the split field magnet detector at the CERN Intersecting Storage Rings. The large angular coverage of this detector extends over ±2.5 units of rapidity and ±30° of azimuth with respect to the trigger π0, both towards and away from it. In each of these directions, where we observe similar strong correlations, we present charged particle distributions, in rapidity and momentum. In the hemisphere containing the trigger π0 we have measured the cross section for inclusive production of large transverse momentum ?± mesons. In the opposite hemisphere the data exhibit several features predicted by hard scattering quark-parton models: coplanarity and short-range rapidity correlation for the large transverse momentum secondaries as well as a transverse momentum sharing distribution similar to that observed in deep inelastic electro-production and in e+e? collisions. 相似文献
94.
Ruthenium shows promise for use as a chemical modifier for the determination of ultratrace quantities of lead in solution when compared with the popular and widely used palladium. There is experimental evidence that ruthenium reacts with lead in the graphite tube to form the intermetallic compound PbRu2. The amount of ruthenium had a dramatic effect on the absorbance profile for the lead signal. 相似文献
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S. Thore S. L. McDonald R. Gonzalez N. P. Ritchey T. W. Ruefli K. K. Sinha 《Annals of Operations Research》1996,68(3):409-422
The gradual exhaustion of existing deposits of a depletable non-renewable resource such as oil tends to shift the supply price curve of the resource upwards, increasing its marginal cost. Advances in technologies for exploration and production act as a brake on such upward shifts. Thus, there is a tug-of-war between the gradual exhaustion of existing deposits and technological progress. Using a recently developed constrained least-squares regression technique, we demonstrate that technological progress was the dominant force of the two during the first part of this century, causing a secular drop in marginal costs, but that this situation eventually was reversed, and that the gradual exhaustion of deposits gained the upper hand, causing marginal costs to increase. The turning point occurred around 1971–72. We also discuss the forecasting of the possible current upward drift of marginal costs. 相似文献
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