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1.
In 1965 Knuth (J. Algebra 2 (1965) 182) noticed that a finite semifield was determined by a 3-cube array (aijk) and that any permutation of the indices would give another semifield. In this article we explain the geometrical significance of these permutations. It is known that a pair of functions (f,g) where f and g are functions from GF(q) to GF(q) with the property that f and g are linear over some subfield and g(x)2+4xf(x) is a non-square for all x∈GF(q)∗, q odd, give rise to certain semifields, one of which is commutative of rank 2 over its middle nucleus, one of which arises from a semifield flock of the quadratic cone, and another that comes from a translation ovoid of Q(4,q). We show that there are in fact six non-isotopic semifields that can be constructed from such a pair of functions, which will give rise to six non-isomorphic semifield planes, unless (f,g) are of linear type or of Dickson-Kantor-Knuth type. These six semifields fall into two sets of three semifields related by Knuth operations. 相似文献
2.
Vladislav?Tomi?i?Email author Vjekoslav?Butorac Jadranka?Viher Vladimir?Simeon 《Journal of solution chemistry》2005,34(6):613-616
The effect of temperature on the π∗←π transition band in the UV absorption spectrum of NO3−(aq) centered at ≈200 nm was studied in the temperature range 10–70 ∘C. The observed temperature independence of this band was in contrast to the significant influence of temperature on the nitrate π∗←n transition reported recently by us. However, taking into account the electronic states involved in both the transitions, it was concluded that this finding was in accordance with our previous assumption that interconversion between spectrally distinct (with respect to π∗←n band) nitrate species included the rupture/formation of hydrogen bond(s) in the hydration shell of the nitrate ion. 相似文献
3.
By an appropriate choice of cation, three of the four possible aldols from the reactions of the chiral α-silyloxy ketone 1 with aldehydes may be obtained. The , lithium enolate provides 6, the , boron enolate gives 7, and the magnesium enolate affords 8. 相似文献
4.
We propose finitely convergent methods for solving convex feasibility problems defined over a possibly infinite pool of constraints. Following other works in this area, we assume that the interior of the solution set is nonempty and that certain overrelaxation parameters form a divergent series. We combine our methods with a very general class of deterministic control sequences where, roughly speaking, we require that sooner or later we encounter a violated constraint if one exists. This requirement is satisfied, in particular, by the cyclic, repetitive and remotest set controls. Moreover, it is almost surely satisfied for random controls.
相似文献5.
Khaja Basheeruddin Vicki Rothman Simeon Margolis 《Applied biochemistry and biotechnology》1985,11(2):133-140
We have immobilized E.coli alkaline phosphatase (EC 3.1.3.1) by linking it covalently to sepharose 4B. This preparation has several advantages over
the soluble enzyme. The immobilized enzyme is easily separable from other constituents in incubation mixtures. The immobilized
enzyme can be reused repeatedly and is more stable than the soluble enzyme to heat treatment in the presence of 10 mM Mg2+. The insoluble and soluble phosphatases removed 75 and77%, respectively, of the inorganic phosphorus from casein. The immobilized enzyme inactivated two enzymes believed to be active
in the phosphorylated state, acyl-CoA : cholesterol acyltransferase (ACAT) by 39% and NADPH-cytochrome P-450 reductase by
89%. The utility of immobilized alkaline phosphatase for studying the phosphorylation and dephosphorylation of soluble or
membrane-bound enzymes and proteins is discussed. 相似文献
6.
We introduce the concept of a pentagonal geometry as a generalization of the pentagon and the Desargues configuration, in the same vein that the generalized polygons share the fundamental properties of ordinary polygons. In short, a pentagonal geometry is a regular partial linear space in which for all points x, the points not collinear with the point x, form a line. We compute bounds on their parameters, give some constructions, obtain some nonexistence results for seemingly feasible parameters and suggest a cryptographic application related to identifying codes of partial linear spaces. 相似文献
7.
Evgeniy Pustylnik Simeon Reich Alexander J. Zaslavski 《Journal of Approximation Theory》2012,164(5):611-624
We provide sufficient conditions for strong and uniform (on bounded subsets of initial points) convergence of infinite products of orthogonal projections and other (possibly nonlinear) nonexpansive operators in a Hilbert space. Our main tools are new estimates of the inclination of a finite tuple of closed linear subspaces. 相似文献
8.
The convergence of a finite element scheme approximating a nonlinear system of integro-differential equations is proven. This system arises in mathematical modeling of the process of a magnetic field penetrating into a substance. Properties of existence, uniqueness and asymptotic behavior of the solutions are briefly described. The decay of the numerical solution is compared with both the theoretical and finite difference results. 相似文献
9.
Simeon Reich Alexander J. Zaslavski 《Journal of Fixed Point Theory and Applications》2010,8(2):395-403
We use the concept of porosity in order to establish a generic stable convergence theorem for infinite products of nonexpansive
mappings in Banach spaces. 相似文献
10.
We present several results concerning the asymptotic behavior of (random) infinite products of generic sequences of positive linear operators on an ordered Banach space. In addition to a weak ergodic theorem we also obtain convergence to an operator of the formf(·) wheref is a continuous linear functional and is a common fixed point. 相似文献