Search

Your search keyword '"Loda B"' showing total 6 results
Start Over Author "Loda B"
6 results on '"Loda B"'

1. On the height and relational complexity of a finite permutation group

Author

Gill, N, Loda, B, Spiga, P, Gill N., Loda B., Spiga P., Gill, N, Loda, B, Spiga, P, Gill N., Loda B., and Spiga P.

Abstract

Let G be a permutation group on a set of size t. We say that is an independent set if its pointwise stabilizer is not equal to the pointwise stabilizer of any proper subset of. We define the height of G to be the maximum size of an independent set, and we denote this quantity. In this paper, we study for the case when G is primitive. Our main result asserts that either {H}(G) or else G is in a particular well-studied family (the primitive large-base groups). An immediate corollary of this result is a characterization of primitive permutation groups with large relational complexity, the latter quantity being a statistic introduced by Cherlin in his study of the model theory of permutation groups. We also study, the maximum length of an irredundant base of G, in which case we prove that if G is primitive, then either I(G) 7 log t or else, again, G is in a particular family (which includes the primitive large-base groups as well as some others).

Published
2022

5. On the height and relational complexity of a finite permutation group

Author

Pablo Spiga, Bianca Lodá, Nick Gill, Gill, N, Loda, B, and Spiga, P

Subjects
Model theory, relational complexity, 20B25, 20B15, General Mathematics, 0102 computer and information sciences, Group Theory (math.GR), Characterization (mathematics), Lambda, 01 natural sciences, Combinatorics, Set (abstract data type), Base (group theory), FOS: Mathematics, Mathematics - Combinatorics, 0101 mathematics, Mathematics, Pointwise, permutation group, base size, 010102 general mathematics, height of a permutation group, Permutation group, TheoryofComputation_MATHEMATICALLOGICANDFORMALLANGUAGES, 010201 computation theory & mathematics, Independent set, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Combinatorics (math.CO), Mathematics - Group Theory
Abstract

Let $G$ be a permutation group on a set $\Omega$ of size $t$. We say that $\Lambda\subseteq\Omega$ is an independent set if its pointwise stabilizer is not equal to the pointwise stabilizer of any proper subset of $\Lambda$. We define the height of $G$ to be the maximum size of an independent set, and we denote this quantity $\mathrm{H}(G)$. In this paper we study $\mathrm{H}(G)$ for the case when $G$ is primitive. Our main result asserts that either $\mathrm{H}(G)< 9\log t$, or else $G$ is in a particular well-studied family (the "primitive large--base groups"). An immediate corollary of this result is a characterization of primitive permutation groups with large "relational complexity", the latter quantity being a statistic introduced by Cherlin in his study of the model theory of permutation groups. We also study $\mathrm{I}(G)$, the maximum length of an irredundant base of $G$, in which case we prove that if $G$ is primitive, then either $\mathrm{I}(G), Comment: 26 pages; updated version based on reviewer's comments -- in particular Lemma 2.6 is new

Published
2020
Full Text
View/download PDF

6. Serotype distribution and antimicrobial susceptibilities of nasopharyngeal isolates of Streptococcus pneumoniae from healthy children in the 13-valent pneumococcal conjugate vaccine era.

Author

Zuccotti G, Mameli C, Daprai L, Garlaschi ML, Dilillo D, Bedogni G, Faccini M, Gramegna M, Torresani E, Ballerini E, Benincaso A, Bonvissuto M, Bricalli D, Brioschi M, Calloni CS, Camiletti MI, Colella G, De Angelis L, Decarlis S, Di Nello F, Dozzi M, Galli E, Gandini V, Giuliani MG, Laviola F, Loda B, Macedoni M, Mazzucchi E, Metta MG, Moscatiello A, Nannini P, Petruzzi M, Picicco D, Picciotti M, Pisanelli S, Porta N, Ramponi G, Redaelli F, Rubini R, Sala N, Saitta V, Scelza G, Tiso RM, Tomasetto M, Torcoletti M, Travaini M, Valentini M, and Vessia C

Subjects
Child, Preschool, Cross-Sectional Studies, Drug Resistance, Bacterial, Female, Humans, Infant, Italy, Male, Microbial Sensitivity Tests, Pneumococcal Vaccines administration & dosage, Streptococcus pneumoniae drug effects, Streptococcus pneumoniae isolation & purification, Carrier State microbiology, Nasopharynx microbiology, Pneumococcal Infections epidemiology, Streptococcus pneumoniae classification
Abstract

Few epidemiological data are available since the introduction of 13-valent pneumococcal vaccine (PCV13) in 2010. We conducted a cross-sectional study to estimate the prevalence of Streptococcus pneumoniae (SP) nasopharyngeal carriage in healthy Italian infants and young children and to evaluate the impact of PCV13 on pneumococcal colonization. In the trimester September-December 2011 nasopharyngeal swabs were collected from healthy children aged 3-59 months presenting for routine well careat 16 primary care pediatricians in Milan. SP carriage isolates were serotyped and tested for antimicrobial resistance using EUCAST breakpoints. Among 1250 enrolled children, 618 had received at least 1 dose of PCV13, 292 at least 1 dose of PCV7, 94 a combination of the two vaccines and 246 were not vaccinated. The prevalence of SP carriage was 27% (95% confidence interval [CI] 25-30). At multivariable analysis, age≥25 months (prevalence ratio [PR]=0.74) and use of antibiotics in the previous 3 months (PR=0.67) were associated with lower SP carriage prevalence. Having siblings (PR=1.79 for 1 sibling and PR=2.23 for ≥2 siblings), day-care attendance (PR=2.27) and respiratory tract infections in the previous 3 months (PR=1.39) were associated with higher SP carriage prevalence. The immunization status for SP was not associated with SP carriage at univariable or at multivariable analysis. The most common carriage isolates were 6C, 19A and 23A. The prevalence of the six additional PCV13 serotypes carriage in children appropriately vaccinated with PCV13 was lower than in children appropriately vaccinated with PCV7 (0 vs. 0.060); the greater reduction in prevalence of carriage was observed for serotype 19A (0 vs. 0.041). Serotype 6C was the most common drug-resistant serotype (17.2%). Further epidemiological studies are needed to assess changes in circulating SP serotypes following the large-scale introduction of PCV13., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Published
2014
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results