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11.
Walter D. Neumann Paul Norbury 《Transactions of the American Mathematical Society》2003,355(2):519-538
We show that although the fundamental group of the complement of an algebraic affine plane curve is not easy to compute, it possesses a more accessible quotient, which we call the Orevkov invariant.
12.
This article completes and simplifies earlier results on the derivation of best linear, or affine, unbiased estimates in the general Gauss-Markov model with a singular dispersion matrix and additional restrictions under very general conditions. We provide the class of all linear representations of the best affine unbiased estimator with precise statements concerning its indeterminacy. 相似文献
13.
Walter Feit 《Israel Journal of Mathematics》1993,82(1-3):141-156
LetK be a field and letG be a finite group.G isK-admissible if there exists a Galois extensionL ofK withG=Gal(L/K) such thatL is a maximal subfield of a centralK-division algebra. This paper contains a characterization of those number fields which areQ
16-admissible. This is the same class of number fields which are 2A
6=SL(2, 9) and 2A
7 admissible.
Dedicated to John Thompson to celebrate his Wolf Prize in Mathematics 1992 相似文献
14.
The sensitivity of neutron-proton scattering observables to the recently reported charge-independence breaking of the isospinT=13
P nucleon-nucleon interaction has been calculated. It is shown that only the analyzing powerA
y
() at extreme forward angles and at =90° c.m. and the spin-correlation coefficientA
zx
() at 90° c.m. exhibit a measurable sensitivity. It is concluded that the determination ofA
y
at 90° c.m. is currently the most accurate approach to verify independently charge-independence breaking in the3
P nucleon-nucleon phase shifts, considering the status of present experimental techniques. 相似文献
15.
Walter A. Carnielli 《Studies in Applied Mathematics》1990,82(1):59-69
A hyper-rook domain of an element x in the space (words of length n over alphabets with k elements) is a sphere with center x and fixed radius j in Hamming distance. The number j determines the dimension of the hyper-rook domain. The classical (and far from solved) problem of covering by rook domains (here considered as the 1-dimensional case) is the problem of finding minimal coverings of by such spheres. Very few results are known in the literature for dimensions ≥ 2. We prove in this paper certain classes of inequalities based on coverings using matrices, which give upper and lower bounds for several cases of the problem for higher dimensions. 相似文献
16.
17.
Richard A. Reid Walter A. StarkJr 《The Journal of the Operational Research Society》1988,39(2):135-139
Individual/group replacement models were used to identify the minimum-cost policy for replacing protective gloves that are utilized in product fabrication at a nuclear processing facility. Since historical data on glove longevity were not available to determine the failure-rate distribution, the classical replacement model for items that fail was modified to consider glove life as a normally distributed variable. Moreover, the absence of replacement-cost required that the classical model be transformed to incorporate the ratio of single to unit-group replacement cost. Sensitivity analysis on these two input parameter values provided guidance for the development of an appropriate replacement policy. 相似文献
18.
Elliott H. Lieb Israel M. Sigal Barry Simon Walter Thirring 《Communications in Mathematical Physics》1988,116(4):635-644
LetN(Z) denote the number of electrons which a nucleus of chargeZ can bind in non-relativistic quantum mechanics (assuming that electrons are fermions). We prove thatN(Z)/Z1 asZ.Research partially supported by the NSERC under Grant NA7901 and by the USNSF under Grants DMS-8416049 and PHY 85-15288-A01 相似文献
19.
E. Braun G. Jackel B. Roden J. G. Sereni D. Wohlleben 《Zeitschrift für Physik B Condensed Matter》1988,72(2):169-173
We have measured the specific heat, the electrical resistance and the magnetic susceptibility of YBa2Cu3O7–x in a superconducting (sc) and in a non-superconducting (nsc) version. The latter was obtained by inducing a small loss of oxygen. In the sc sample we find a jump of the specific heat with C=3.6 J mole–1 K–1. Below the maximum nearT
c
the specific heat of the sc version drops too fast for an electronic effect alone: there is a cross-over from excess to deficiency already at 0.9T
c
. The specific heat of the nsc version shows a change of slope in the temperature range between 70 and 80 K, which indicates the existence of a second specific heat anomaly, which apparently exists independently of that due to the onset of superconductivity and explains at least partially the premature crossover.Alexander von Humboldt fellow. On leave in absence from Centro Atomico Bariloche—CNEA Argentina 相似文献
20.