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31.
Alexander?A.?DavydovEmail author Giorgio?Faina Fernanda?Pambianco 《Designs, Codes and Cryptography》2005,37(1):61-80
In the binary projective spaces PG(n,2) k-caps are called large if k > 2n-1 and smallif k ≤ 2n-1. In this paper we propose new constructions producing infinite families of small binary complete caps.AMS Classification: 51E21, 51E22, 94B05 相似文献
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Alexander A. Davydov Giorgio Faina Stefano Marcugini Fernanda Pambianco 《Journal of Geometry》2005,82(1-2):50-62
The spectrum of possible sizes k of complete k-arcs in finite projective planes PG(2, q) is investigated by computer search. Backtracking algorithms that try to construct complete arcs joining the orbits of some
subgroup of collineation group PΓ L (3, q) and randomized greedy algorithms are applied. New upper bounds on the smallest size of a complete arc are given for q = 41, 43, 47, 49, 53, 59, 64, 71 ≤ q ≤ 809, q ≠ 529, 625, 729, and q = 821. New lower bounds on the second largest size of a complete arc are given for q = 31, 41, 43, 47, 53, 125. Also, many new sizes of complete arcs are obtained for 31 ≤ q ≤ 167. 相似文献
35.
Jürgen Bierbrauer Daniele Bartoli Giorgio Faina Stefano Marcugini Fernanda Pambianco 《Designs, Codes and Cryptography》2018,86(3):611-621
We study a large family of semifields in odd characteristic, which contains the commutative Budaghyan–Helleseth semifields as well as semifields which are not isotopic to commutative semifields. Using a large group of autotopisms we obtain a complete classification result in certain parametric subcases. 相似文献
36.
Elena S. Zhitova Andrey A. Zolotarev Sergey V. Krivovichev Alexey G. Goncharov Faina A. Gabdrakhmanova Nikolay V. Vladykin Maria G. Krzhizhanovskaya Vladimir V. Shilovskikh Natalia S. Vlasenko Anatoly A. Zolotarev 《Hyperfine Interactions》2017,238(1):96
The high-temperature behavior of bafertisite was studied by combination of techniques in order to characterize the temperature-induced iron oxidation associated with deprotonation of an octahedral layer. The chemical formula of bafertisite from Darai-Pioz alkaline complex (Tajikistan) determined by electron-microprobe analyzes and Mössbauer spectroscopy is Ba 2.11(Fe\({}_{2.70}^{2+}\)Fe\({}_{0.17}^{3+}\)Mn 1.09Zr 0.04Na 0.03) (Ti 1.96Nb 0.07)(Si 2 O 7)2 O 2(OH 1.29 O 0.65 F 0.06)F 2. In situ high-temperature powder X-ray diffraction revealed abrupt shift of reflections to the high-angle region and reduction of their intensity at T >?525 °C. The Mössbauer spectroscopy studies indicated that the crystal structure of bafertisite contains Fe in octahedral sites as predominantly ferric ions with Fe 3+/ ΣFe =?0.06, whereas bafertisite annealed at T =?600 °C has Fe in the same position with Fe 3+/ ΣFe up to 0.39. The differential scanning calorimetry and thermogravimetric analyzes reveal the occurrence of a broad exothermic effect at T ~ 537 °C associated with the mass loss corresponding to deprotonation. Since in the studied sample of bafertisite, Fe 2+ apfu strongly prevails over OH apfu, the stoichiometric (charged-balanced) high-temperature oxidized modification cannot be obtained. In the paper, the high-temperature behavior of bafertisite is discussed and compared to that of astrophyllite. 相似文献
37.
Giorgio Faina 《Rendiconti del Circolo Matematico di Palermo》1994,43(2):285-302
LetE be an abstract infinite or finite set with |E|≥3 and letB be a non empty family of subsets ofE such that there exists at least a partitionF ofE withF?B. We callgeneralized cone some incidence structures (E,B,F) which comprehend ovoidal and Miquelian Laguerre planes, special Laguerre planes, Parabeln-Ebene and other interesting incidence structures. In this paper we investigate suchgeneralized cones and their automorphism groups and give some characterizations of ovoidal (Miquelian) Laguerre planes. 相似文献
38.
Minimax nonhomogeneous linear estimators of scalar linear parameter functions are studied in the paper under restrictions
on the parameters and variance-covariance matrix. The variance-covariance matrix of the linear model under consideration is
assumed to be unknown but from a specific set R of nonnegativedefinite matrices. It is shown under this assumption that, without
any restriction on the parameters, minimax estimators correspond to the least-squares estimators of the parameter functions
for the “worst” variance-covariance matrix. Then the minimax mean-square error of the estimator is derived using the Bayes
approach, and finally the exact formulas are derived for the calculation of minimax estimators under elliptical restrictions
on the parameter space and for two special classes of possible variance-covariance matrices R. For example, it is shown that
a special choice of a constant q
0
and a matrixW
0 defining one of the above classes R leads to the well known Kuks—Olman admissible estimator (see [16]) with a known variance-covariance
matrixW
0. Bibliography:32 titles.
Translated fromObchyslyuval'na ta Prykladna Matematyka, No. 81, 1997, pp. 79–92. 相似文献
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The increasing resistance of bacteria to antibiotics is a serious problem, caused in part by excessive and improper use of these drugs. One alternative to traditional antibiotic therapy is photodynamic antimicrobial chemotherapy (PACT) which is based on the use of a photosensitizer (PS), activated by illumination with visible light. The poor penetration of visible light through the skin limits the application of PACT to the treatment of skin infections or the use of invasive procedures. To overcome this problem we report the exploitation of light emitted as a result of the chemiluminescent reaction of luminol to excite the PS and we call this process chemiluminescent photodynamic antimicrobial therapy (CPAT). We studied the effect of free and liposome-encapsulated PS (methylene blue or toluidine blue) on bacteria under excitation by either white external light or chemiluminescence emitted by free or liposome-enclosed luminol. PACT showed slightly better performance that CPAT for free and encapsulated PS for both types of bacteria. CPAT resulted in a three log suppression of Staphylococcus aureus and two log suppression of Escherichia coli growth. The use of CPAT may prove to be a novel and more effective form of antimicrobial therapy, particularly for internal infections not easily accessible to traditional PACT. 相似文献