scholarly journals A characterization of the Petersen-type geometry of the McLaughlin group

2000 ◽  
Vol 128 (1) ◽  
pp. 21-44 ◽  
Author(s):  
B. BAUMEISTER ◽  
A. A. IVANOV ◽  
D. V. PASECHNIK
Keyword(s):  
Automorphism Group ◽  
Universal Cover ◽  
Classification Problem ◽  
Alternating Group ◽  
Sporadic Simple Group ◽  
Mathieu Group ◽  
Transitive Automorphism Group ◽  
The Right ◽  
Simply Connected

The McLaughlin sporadic simple group McL is the flag-transitive automorphism group of a Petersen-type geometry [Gscr ] = [Gscr ](McL) with the diagramdiagram herewhere the edge in the middle indicates the geometry of vertices and edges of the Petersen graph. The elements corresponding to the nodes from the left to the right on the diagram P33 are called points, lines, triangles and planes, respectively. The residue in [Gscr ] of a point is the P3-geometry [Gscr ](Mat22) of the Mathieu group of degree 22 and the residue of a plane is the P3-geometry [Gscr ](Alt7) of the alternating group of degree 7. The geometries [Gscr ](Mat22) and [Gscr ](Alt7) possess 3-fold covers [Gscr ](3Mat22) and [Gscr ](3Alt7) which are known to be universal. In this paper we show that [Gscr ] is simply connected and construct a geometry [Gscr ]˜ which possesses a 2-covering onto [Gscr ]. The automorphism group of [Gscr ]˜ is of the form 323McL; the residues of a point and a plane are isomorphic to [Gscr ](3Mat22) and [Gscr ](3Alt7), respectively. Moreover, we reduce the classification problem of all flag-transitive Pmn-geometries with n, m [ges ] 3 to the calculation of the universal cover of [Gscr ]˜.

OD-Characterization of Certain Finite Groups Having Connected Prime Graphs

2010 ◽  
Vol 17 (01) ◽  
pp. 121-130 ◽  
Author(s):  
A. R. Moghaddamfar ◽  
A. R. Zokayi
Keyword(s):  
Finite Group ◽  
Automorphism Group ◽  
Symmetric Group ◽  
Finite Groups ◽  
Alternating Group ◽  
Degree Pattern ◽  
Prime Graphs ◽  
Group A ◽  
A Finite Group

The degree pattern of a finite group G denoted by D(G) was introduced in [5]. We say that G is k-fold OD-characterizable if there exist exactly k non-isomorphic finite groups having the same order and same degree pattern as G. In the present article, we show that the alternating group A10 and the automorphism group Aut (McL) are 2-fold OD-characterizable, while the automorphism group Aut (J2) is 3-fold OD-characterizable and the symmetric group S10 is 8-fold OD-characterizable. It is worth mentioning that the prime graphs associated to these groups are connected and, in fact, among the groups with this property, they are the first groups which are investigated for OD-characterizability.

scholarly journals Functional Characterization of the mazEF Toxin-Antitoxin System in the Pathogenic Bacterium Agrobacterium tumefaciens

2021 ◽  
Vol 9 (5) ◽  
pp. 1107
Author(s):  
Wonho Choi ◽  
Yoshihiro Yamaguchi ◽  
Ji-Young Park ◽  
Sang-Hyun Park ◽  
Hyeok-Won Lee ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Physiological Function ◽  
Functional Characterization ◽  
Site Directed Mutagenesis ◽  
In Vitro Assays ◽  
Cell Growth Inhibition ◽  
The Right

Agrobacterium tumefaciens is a pathogen of various plants which transfers its own DNA (T-DNA) to the host plants. It is used for producing genetically modified plants with this ability. To control T-DNA transfer to the right place, toxin-antitoxin (TA) systems of A. tumefaciens were used to control the target site of transfer without any unintentional targeting. Here, we describe a toxin-antitoxin system, Atu0939 (mazE-at) and Atu0940 (mazF-at), in the chromosome of Agrobacterium tumefaciens. The toxin in the TA system has 33.3% identity and 45.5% similarity with MazF in Escherichia coli. The expression of MazF-at caused cell growth inhibition, while cells with MazF-at co-expressed with MazE-at grew normally. In vivo and in vitro assays revealed that MazF-at inhibited protein synthesis by decreasing the cellular mRNA stability. Moreover, the catalytic residue of MazF-at was determined to be the 24th glutamic acid using site-directed mutagenesis. From the results, we concluded that MazF-at is a type II toxin-antitoxin system and a ribosome-independent endoribonuclease. Here, we characterized a TA system in A. tumefaciens whose understanding might help to find its physiological function and to develop further applications.

scholarly journals Characterization of Spatial Planning in Brazil: The Right to the City in Theory and Practice

2019 ◽  
Vol 34 (4) ◽  
pp. 419-437 ◽  
Author(s):  
Roberto Rocco ◽  
Luciana Royer ◽  
Fábio Mariz Gonçalves
Keyword(s):  
Spatial Planning ◽  
Theory And Practice ◽  
Right To The City ◽  
The Right ◽  
The City

scholarly journals HEYDE’S CHARACTERIZATION THEOREM FOR DISCRETE ABELIAN GROUPS

2010 ◽  
Vol 88 (1) ◽  
pp. 93-102 ◽  
Author(s):  
MARGARYTA MYRONYUK
Keyword(s):  
Abelian Group ◽  
Automorphism Group ◽  
Real Line ◽  
Linear Form ◽  
Conditional Distribution ◽  
Random Variables ◽  
Characterization Theorem ◽  
Gaussian Distributions ◽  
Discrete Abelian Group

AbstractLet X be a countable discrete abelian group with automorphism group Aut(X). Let ξ1 and ξ2 be independent X-valued random variables with distributions μ1 and μ2, respectively. Suppose that α1,α2,β1,β2∈Aut(X) and β1α−11±β2α−12∈Aut(X). Assuming that the conditional distribution of the linear form L2 given L1 is symmetric, where L2=β1ξ1+β2ξ2 and L1=α1ξ1+α2ξ2, we describe all possibilities for the μj. This is a group-theoretic analogue of Heyde’s characterization of Gaussian distributions on the real line.

Kleinian characterization of asymptotic symmetries of real general relativity

1993 ◽  
Vol 441 (1913) ◽  
pp. 465-471 ◽  
Keyword(s):  
General Relativity ◽  
Automorphism Group ◽  
Group Action ◽  
Radon Transform ◽  
Symmetry Groups ◽  
Asymptotic Symmetry ◽  
The Real ◽  
The Given ◽  
Asymptotic Symmetries

According to Klein’s Erlanger programme, one may (indirectly) specify a geometry by giving a group action. Conversely, given a group action, one may ask for the corresponding geometry. Recently, I showed that the real asymptotic symmetry groups of general relativity (in any signature) have natural ‘projective’ classical actions on suitable ‘Radon transform’ spaces of affine 3-planes in flat 4-space. In this paper, I give concrete models for these groups and actions. Also, for the ‘atomic’ cases, I give geometric structures for the spaces of affine 3-planes for which the given actions are the automorphism group.

Identification and characterization of the centromere from chromosome XIV in Saccharomyces cerevisiae

1985 ◽  
Vol 5 (11) ◽  
pp. 2887-2893
Author(s):  
M Neitz ◽  
J Carbon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Restriction Fragment ◽  
Dna Sequences ◽  
Yeast Genome ◽  
Ura3 Gene ◽  
Dna Restriction ◽  
Meiotic Analyses ◽  
The Right ◽  
In Cis

A functional centromere located on a small DNA restriction fragment from Saccharomyces cerevisiae was identified as CEN14 by integrating centromere-adjacent DNA plus the URA3 gene by homologous recombination into the yeast genome and then by localizing the URA3 gene to chromosome XIV by standard tetrad analysis. DNA sequence analysis revealed that CEN14 possesses sequences (elements I, II, and III) that are characteristic of other yeast centromeres. Mitotic and meiotic analyses indicated that the CEN14 function resides on a 259-base-pair (bp) RsaI-EcoRV restriction fragment, containing sequences that extend only 27 bp to the right of the element I to III region. In conjunction with previous findings on CEN3 and CEN11, these results indicate that the specific DNA sequences required in cis for yeast centromere function are contained within a region about 150 bp in length.

Role of MRI in Detecting and Characterizing Small Hepatic Focal Lesions

QJM ◽  
2021 ◽  
Vol 114 (Supplement_1) ◽  
Author(s):  
Rania Ali Maarouf ◽  
Ali Haggag Ali ◽  
Mahmoud Abdelatif Onsy
Keyword(s):  
Tumor Staging ◽  
Left Lobe ◽  
Diagnostic Process ◽  
Liver Imaging ◽  
Focal Lesions ◽  
Focal Hepatic Lesions ◽  
Malignant Lesions ◽  
Hepatic Lesions ◽  
The Right

Abstract Background Despite the recent advances in liver imaging, the detection and characterization of small hepatic focal lesions is still a real challenge. Particularly in cancer patients where the characterization of a small HFL as thus the precise tumor staging is critical for optimal treatment planning. Aim of the Work To explore the effectiveness, and hence the clinical utility, of MRI detection and characterization of small focal hepatic lesions either only discovered on MRI or as a further work up of CT/US-indeterminate lesions. Patients and Methods We reviewed our database for individuals who underwent liver MR imaging between March 2018 and March 2019 for the evaluation of small hepatic lesions that were discovered for the first time or had been previously visualized on routinely performed CT and had been considered indeterminate. Results The present study included 44 patients of which 26 were males (59.1%) and 18 were females (40.9%). The age range of the study group was 19 to 77 years. The mean age for Malignant lesions was 51 years. The right lobe of liver was involved in 23 cases (52.3%), left lobe in 5 cases (11.4%) and both lobes in 16 cases (36.4%). There were 30 (68.18%) benign, 13 (29.54%) malignant lesions and 1 (2.3%) indeterminate, hemangiomas were predominant in benign lesions whereas hepatocellular carcinomas were predominant in malignant lesions. N'TRI could characterize 92% cases. Conclusion The diagnostic process of small hepatic focal lesions, either detection or characterization or both, continues to represent a challenge. Contrast-enhanced MR can accurately detect and characterize majority of small hepatic focal lesions.

scholarly journals Cubic arc-transitive Cayley graphs on Frobenius groups

2018 ◽  
Vol 17 (07) ◽  
pp. 1850126 ◽  
Author(s):  
Hailin Liu ◽  
Lei Wang
Keyword(s):  
Automorphism Group ◽  
Cayley Graph ◽  
Cayley Graphs ◽  
Frobenius Groups

A Cayley graph [Formula: see text] is called arc-transitive if its automorphism group [Formula: see text] is transitive on the set of arcs in [Formula: see text]. In this paper, we give a characterization of cubic arc-transitive Cayley graphs on a class of Frobenius groups.

scholarly journals (M,β)-Stability of Positive Linear Systems

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Octavian Pastravanu ◽  
Mihaela-Hanako Matcovschi
Keyword(s):  
Linear System ◽  
Linear Systems ◽  
Transient Behavior ◽  
Short Term ◽  
Time Dynamics ◽  
The Right ◽  
Long Term Behavior ◽  
Stability Concept

The main purpose of this work is to show that the Perron-Frobenius eigenstructure of a positive linear system is involved not only in the characterization of long-term behavior (for which well-known results are available) but also in the characterization of short-term or transient behavior. We address the analysis of the short-term behavior by the help of the “(M,β)-stability” concept introduced in literature for general classes of dynamics. Our paper exploits this concept relative to Hölder vectorp-norms,1≤p≤∞, adequately weighted by scaling operators, focusing on positive linear systems. Given an asymptotically stable positive linear system, for each1≤p≤∞, we prove the existence of a scaling operator (built from the right and left Perron-Frobenius eigenvectors, with concrete expressions depending onp) that ensures the best possible values for the parametersMandβ, corresponding to an “ideal” short-term (transient) behavior. We provide results that cover both discrete- and continuous-time dynamics. Our analysis also captures the differences between the cases where the system dynamics is defined by matrices irreducible and reducible, respectively. The theoretical developments are applied to the practical study of the short-term behavior for two positive linear systems already discussed in literature by other authors.

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