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91.
Steiner quadruple systems are set systems in which every triple is contained in a unique quadruple. It is well known that Steiner quadruple systems of order v, or SQS(v), exist if and only if . Universal cycles, introduced by Chung, Diaconis, and Graham in 1992, are a type of cyclic Gray code. Overlap cycles are generalizations of universal cycles that were introduced in 2010 by Godbole, et al. Using Hanani's SQS constructions, we show that for every with there exists an SQS(v) that admits a 1‐overlap cycle. 相似文献
92.
A number of applications of Steiner triple systems (e.g. disk erasure codes) exist that require a special ordering of its blocks. Universal cycles, introduced by Chung, Diaconis, and Graham in 1992, and Gray codes are examples of listing elements of a combinatorial family in a specific manner, and Godbole invented the following generalization of these in 2010. 1-overlap cycles require a set of strings to be ordered so that the last letter of one string is the first letter of the next. In this paper, we prove the existence of 1-overlap cycles for automorphism free Steiner triple systems of each possible order. Since Steiner triple systems have the property that each block can be represented uniquely by a pair of points, these 1-overlap cycles can be compressed by omitting non-overlap points to produce rank two universal cycles on such designs, expanding on the results of Dewar. 相似文献
93.
94.
95.
left order in Q and Q is a semigroup of left quotients of S if every q∈Q can be written as q=a^*b for some a, b∈S where a^* denotes the inverse of a in a subgroup of Q and if,
in addition, every square-cancellable element of S lies in a subgroup of Q. Perhaps surprisingly, a semigroup, even a commutative
cancellative semigroup, can have non-isomorphic semigroups of left quotients. We show that if S is a cancellative left order
in Q then Q is completely regular and the {\cal D}-classes of Q are left groups. The semigroup S is right reversible and its
group of left quotients is the minimum semigroup of left quotients of S.
The authors are grateful to the ARC for its generous financial support. 相似文献
96.
Victoria Gesheva 《Applied biochemistry and biotechnology》2009,158(1):20-24
Experimental mathematical designs were applied for optimization of a nutrient medium for biosynthesis of the antifungal antibiotic
AK-111-81 by phosphate-deregulated mutant of Streptomyces hygroscopicus 111-81. Antifungal antibiotic AK-111-81 possesses well-expressed activity against Fusarium graminearum and other phytopathogenic fungi. The level of the production of the antibiotic AK-111-81 on this medium is more than three
times higher than on the initial medium. The optimized quantitative composition of the nutrient culture media is (g/l): glucose,
20; soy meal, 18; ammonium succinate, 3; CaCO3, 1. 相似文献
97.
Victoria Ivanova Thierry Boghosian Olivier Rabin 《Accreditation and quality assurance》2007,12(9):491-493
This article provides a brief perspective of the World Anti-Doping Agency (WADA) in the context of the fight against doping
in sport and of the WADA Proficiency Testing Program as an essential element of the World Anti-Doping Program. The WADA Proficiency
Testing Program exists within the framework of the WADA-accredited laboratories and is aimed at improving the effectiveness
of the fight against doping by testing the ability of the laboratories to reliably identify and measure the substances and
methods defined in the WADA Prohibited List. The paper provides an overview of the WADA Proficiency Testing scheme with respect
to organization, test composition and evaluation of anti-doping methods and techniques. Scientific research is mentioned in
the context of WADA’s involvement in generating reference materials for improvement of analytical activities of the WADA-accredited
laboratories. WADA’s funding of a reference material for 19-norandrosterone in human urine is illustrated as an example. 相似文献
98.
Victoria Volkis Elena Smolensky Anatoli Lisovskii Moris S. Eisen 《Journal of polymer science. Part A, Polymer chemistry》2005,43(19):4505-4516
The effect of solvents (toluene, dichloromethane, and hexane) was studied on the polymerization of propylene with the octahedral complexes bis(trimethylsilyl)benzamidinate titanium dichloride(a), bis(acetylacetonate) titanium dichloride(b), and bis(diethylamino) titanium di‐2‐(diphenylphosphanylamino)pyridine as catalytic precursors and methylalumoxane as the cocatalyst. For comparison, the polymerization was also performed in plain liquid propylene without the addition of any solvent. The obtained polymers were fractionated by refluxing hexane. The activity of the complexes and the molecular weights and tacticities of the whole polymers and their different fractions were the studied parameters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4505–4516, 2005 相似文献
99.
A semigroup with zero isidempotent bounded (IB) if it is the 0-direct union of idempotent generated principal left ideals and the 0-direct union of idempotent generated principal right ideals. Notable examples are completely 0-simple semigroups and the wider class of primitive abundant semigroups. Significant to the structure of these semigroups is that they are all categorical at zero. In this paper we describe IB semigroups that are categorical at zero in terms ofdouble blocked Rees matrix semigroups. This generalises Fountain's characterisation of primitive abundant semigroups via blocked Rees matrix semigroups [1], which in turn yields the Rees theorem for completely 0-simple semigroups. 相似文献
100.
Ravi P. Agarwal Victoria Otero-Espinar Kanishka Perera 《Journal of Mathematical Analysis and Applications》2007,331(2):1263-1274
The aim of this paper is to employ variational techniques and critical point theory to prove some sufficient conditions for the existence of multiple positive solutions to a nonlinear second order dynamic equation with homogeneous Dirichlet boundary conditions. 相似文献