scholarly journals Constructions of Chiral Polytopes of Small Rank

2011 ◽  
Vol 63 (6) ◽  
pp. 1254-1283 ◽  
Author(s):  
Antonio Breda D’Azevedo ◽  
Gareth A. Jones ◽  
Egon Schulte

AbstractAn abstract polytope of rank n is said to be chiral if its automorphism group has precisely two orbits on the flags, such that adjacent flags belong to distinct orbits. This paper describes a general method for deriving new finite chiral polytopes from old finite chiral polytopes of the same rank. In particular, the technique is used to construct many new examples in ranks 3, 4, and 5.

10.37236/7070 ◽  
2017 ◽  
Vol 24 (3) ◽  
Author(s):  
Gabe Cunningham

An abstract polytope is flat if every facet is incident on every vertex. In this paper, we prove that no chiral polytope has flat finite regular facets and finite regular vertex-figures. We then determine the three smallest non-flat regular polytopes in each rank, and use this to show that for $n \geq 8$, a chiral $n$-polytope has at least $48(n-2)(n-2)!$ flags.


10.37236/2149 ◽  
2013 ◽  
Vol 20 (1) ◽  
Author(s):  
Tommaso Traetta

A $k$-factorization of $K_v$ of type $(r, s)$ consists of $k$-factors each of which is the disjoint union of $r$ copies of $K_{k+1}$ and $s$ copies of $K_{k,k}$. By means of what we call the patterned $k$-factorization $F_k(D)$ over an arbitrary group $D$ of order $2s + 1$, it is shown that a $k$-factorization of type $(1, s)$ exists for any $k\ge2$ and for any $s\ge1$ with $D$ being an automorphism group acting sharply transitively on the factor-set. The general method to construct a $k$-factorization $F$ of type $(1, s)$ over an arbitrary 1-factorization $S$ of $K_{2s+2}$ ($F$ is said to be based on $S$) is used to prove that the number of pairwise non-isomorphic $k$-factorizations of this type goes to infinity with $s$. In this paper, we show that the full automorphism group of $F$ is known as soon as we know the one of $S$. In particular, the full automorphism group of $F_k(D)$ is determined for any $k\ge2$, generalizing a result given by P. J. Cameron for patterned 1-factorizations [J London Math Soc 11 (1975), 189-201]. Finally, it is shown that $F_k(D)$ has exactly $(k!)2s+1(2s+1)|Aut(D)|$ automorphisms whenever $D$ is abelian.


Author(s):  
J. R. Fields

The energy analysis of electrons scattered by a specimen in a scanning transmission electron microscope can improve contrast as well as aid in chemical identification. In so far as energy analysis is useful, one would like to be able to design a spectrometer which is tailored to his particular needs. In our own case, we require a spectrometer which will accept a parallel incident beam and which will focus the electrons in both the median and perpendicular planes. In addition, since we intend to follow the spectrometer by a detector array rather than a single energy selecting slit, we need as great a dispersion as possible. Therefore, we would like to follow our spectrometer by a magnifying lens. Consequently, the line along which electrons of varying energy are dispersed must be normal to the direction of the central ray at the spectrometer exit.


Author(s):  
E. Naranjo

Equilibrium vesicles, those which are the stable form of aggregation and form spontaneously on mixing surfactant with water, have never been demonstrated in single component bilayers and only rarely in lipid or surfactant mixtures. Designing a simple and general method for producing spontaneous and stable vesicles depends on a better understanding of the thermodynamics of aggregation, the interplay of intermolecular forces in surfactants, and an efficient way of doing structural characterization in dynamic systems.


2019 ◽  
Vol 25 (2) ◽  
pp. 256-279 ◽  
Author(s):  
Amy Dawel ◽  
Tsz Ying Wong ◽  
Jodie McMorrow ◽  
Callin Ivanovici ◽  
Xuming He ◽  
...  

1991 ◽  
Vol 30 (01) ◽  
pp. 30-35 ◽  
Author(s):  
P. Dujols ◽  
P. Aubas ◽  
C. Baylon ◽  
F. Grémy
Keyword(s):  

This paper describes an automatic procedure for morphosemantic analysis and translation of compound medical terms. This analysis is of interest for the automatic indexation of medical discharge reports and summaries. Since words with the suffix -osis may have many different semantic interpretations, such -osis forms are taken as examples for a general method that avoids the difficulties in interpreting medical terms as reported in other studies.


2018 ◽  
Author(s):  
Victor Laserna ◽  
Tom Sheppard

A versatile approach to the valorization of propargylic alcohols is reported, enabling controlled access to three different products from the same starting materials. Firstly, a general method for the hydroamination of propargylic alcohols with anilines is described using gold catalysis to give 3-hydroxy imines with complete regioselectivity. These 3-hydroxyimines can be reduced to give 1,3-aminoalcohols with high syn seletivity. Alternatively, by using a catalytic quantity of aniline, 3-hydroxyketones can be obtained in high yield directly from propargylic alcohols. Further manipulation of the reaction conditions enables the selective formation of 3-aminoketones via a rearrangement/hydroamination pathway.<br>


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