Search results for "Number"
showing 10 items of 3939 documents
Moduli spaces of rank two aCM bundles on the Segre product of three projective lines
2016
Let P^n be the projective space of dimension n on an algebraically closed field of characteristic 0 and F be the image of the Segre embedding of P^1xP^1xP^1 inside P^7. In the present paper we deal with the moduli spaces of locally free sheaves E on F of rank 2 with h^i(F,E(t))=0 for i=1,2 and each integer t.
Varieties of algebras with pseudoinvolution and polynomial growth
2017
Let A be an associative algebra with pseudoinvolution (Formula presented.) over an algebraically closed field of characteristic zero and let (Formula presented.) be its sequence of (Formula presented.) -codimensions. We shall prove that such a sequence is polynomially bounded if and only if the variety generated by A does not contain five explicitly described algebras with pseudoinvolution. As a consequence, we shall classify the varieties of algebras with pseudoinvolution of almost polynomial growth, i.e. varieties of exponential growth such that any proper subvariety has polynomial growth and, along the way, we shall give also the classification of their subvarieties. Finally, we shall de…
Lie Algebras Generated by Extremal Elements
1999
We study Lie algebras generated by extremal elements (i.e., elements spanning inner ideals of L) over a field of characteristic distinct from 2. We prove that any Lie algebra generated by a finite number of extremal elements is finite dimensional. The minimal number of extremal generators for the Lie algebras of type An, Bn (n>2), Cn (n>1), Dn (n>3), En (n=6,7,8), F4 and G2 are shown to be n+1, n+1, 2n, n, 5, 5, and 4 in the respective cases. These results are related to group theoretic ones for the corresponding Chevalley groups.
Exposing Empirical Links between COVID-19 Situation Report and Available Data: The Case of Nigeria
2020
Ever since the index case of COVID-19 was announced in Nigeria, the number of confirmed cases has gradually increased to 46,140 (about 4.5% of total confirmed cases in Africa) as the time of writing this article. This seemingly low number of confirmed cases has provoked heated debates among researchers. This cross-sectional study explores the Nigerian COVID-19 report to expose some links between the number of confirmed cases, testing, and some environmental conditions. The findings reveal that there is no state in Nigeria which has up to 12 confirmed cases per 10,000 population. That means, the number of confirmed COVID-19 cases is less than 0.15% of the population of people across each sta…
A model of COVID-19 pandemic evolution in African countries
2021
We studied the COVID-19 pandemic evolution in selected African countries. For each country considered, we modeled simultaneously the data of the active, recovered and death cases. In this study, we used a year of data since the first cases were reported. We estimated the time-dependent basic reproduction numbers, $R_0$, and the fractions of infected but unaffected populations, to offer insights into containment and vaccine strategies in African countries. We found that $R_0\leq 4$ at the start of the pandemic but has since fallen to $R_0 \sim 1$. The unaffected fractions of the populations studied vary between $1-10$\% of the recovered cases.
Genetic and Epigenetic Factors of Takotsubo Syndrome: A Systematic Review
2021
Takotsubo syndrome (TTS), recognized as stress’s cardiomyopathy, or as left ventricular apical balloon syndrome in recent years, is a rare pathology, described for the first time by Japanese researchers in 1990. TTS is characterized by an interindividual heterogeneity in onset and progression, and by strong predominance in postmenopausal women. The clear causes of these TTS features are uncertain, given the limited understanding of this intriguing syndrome until now. However, the increasing frequency of TTS cases in recent years, and particularly correlated to the SARS-CoV-2 pandemic, leads us to the imperative necessity both of a complete knowledge of TTS pathophysiology for identifying bi…
The average element order and the number of conjugacy classes of finite groups
2021
Abstract Let o ( G ) be the average order of the elements of G, where G is a finite group. We show that there is no polynomial lower bound for o ( G ) in terms of o ( N ) , where N ⊴ G , even when G is a prime-power order group and N is abelian. This gives a negative answer to a question of A. Jaikin-Zapirain.
Automorphisms of 2–dimensional right-angled Artin groups
2007
We study the outer automorphism group of a right-angled Artin group AA in the case where the defining graph A is connected and triangle-free. We give an algebraic description of Out.AA/ in terms of maximal join subgraphs in A and prove that the Tits’ alternative holds for Out.AA/. We construct an analogue of outer space for Out.AA/ and prove that it is finite dimensional, contractible, and has a proper action of Out.AA/. We show that Out.AA/ has finite virtual cohomological dimension, give upper and lower bounds on this dimension and construct a spine for outer space realizing the most general upper bound. 20F36; 20F65, 20F28
Maximal subgroups and PST-groups
2013
A subgroup H of a group G is said r to permute with a subgroup K of G if HK is a subgroup of G. H is said to be permutable (resp. S-permutable) if it permutes with all the subgroups (resp. Sylow subgroups) of G. Finite groups in which permutability (resp. S-permutability) is a transitive relation are called PT-groups (resp. PST-groups). PT-, PST- and T-groups, or groups in which normality is transitive, have been extensively studied and characterised. Kaplan [Kaplan G., On T-groups, supersolvable groups, and maxmial subgroups, Arch. Math. (Basel), 2011, 96(1), 19-25)] presented some new characterisations of soluble T-groups. The main goal of this paper is to establish PT- and PST-versions o…
Population of lead isotopes in binary reactions using a Rb 94 radioactive beam
2020
8 pags., 9 figs.