5,074 research outputs found
Automorphism groups of polycyclic-by-finite groups and arithmetic groups
We show that the outer automorphism group of a polycyclic-by-finite group is
an arithmetic group. This result follows from a detailed structural analysis of
the automorphism groups of such groups. We use an extended version of the
theory of the algebraic hull functor initiated by Mostow. We thus make
applicable refined methods from the theory of algebraic and arithmetic groups.
We also construct examples of polycyclic-by-finite groups which have an
automorphism group which does not contain an arithmetic group of finite index.
Finally we discuss applications of our results to the groups of homotopy
self-equivalences of K(\Gamma, 1)-spaces and obtain an extension of
arithmeticity results of Sullivan in rational homotopy theory
The effect of physical characteristics on cow price differentials in Kansas
A survey of cow sales was conducted in the fall of 1986 and spring of 1987 at seven Kansas cattle auctions. Several factors significantly influenced cow prices, including health, estimated dressing percentage, lot size, breed, and time of sale. Changes in dressing percentage explained the major portion of cow price variation
The effect of physical characteristics on the price of stocker and feeder cattle
A survey of feeder cattle sales was conducted at seven Kansas cattle auctions during 1986 and 1987. A wide variety of physical characteristics was found to influence feeder cattle prices. The price impact resulting from changes in fill and condition varied seasonally. Although calves showing any signs of health problems received severe price discounts, the presence of other undesirable characteristics also resulted in discounts, but to lesser degrees
Successful elimination of factor VIII inhibitor using cyclosporin A
No abstract available
Altered expression of T cell Immunoglobulin-Mucin (TIM) molecules in bronchoalveolar lavage CD4+ T cells in sarcoidosis
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Different HLA-DRB1 allele distributions in distinct clinical subgroups of sarcoidosis patients
<p>Abstract</p> <p>Background</p> <p>A strong genetic influence by the MHC class II region has been reported in sarcoidosis, however in many studies with different results. This may possibly be caused by actual differences between distinct ethnic groups, too small sample sizes, or because of lack of accurate clinical subgrouping.</p> <p>Subjects and methods</p> <p>In this study we HLA typed a large patient population (n = 754) recruited from one single centre. Patients were sub-grouped into those with Löfgren's syndrome (LS) (n = 302) and those without (non-Löfgren's) (n = 452), and the majority of them were clinically classified into those with recovery within two years (resolving) and those with signs of disease for more than two years (non-resolving). PCR was used for determination of HLA-DRB1 alleles. Swedish healthy blood donors (n = 1366) served as controls.</p> <p>Results</p> <p>There was a dramatic difference in the distribution of HLA alleles in LS compared to non-LS patients (p = 4 × 10<sup>-36</sup>). Most notably, DRB1*01, DRB1*03 and DRB1*14, clearly differed in LS and non-LS patients. In relation to disease course, DRB1*07, DRB1*14 and DRB1*15 generally associated with, while DRB1*01 and DRB1*03 protected against, a non-resolving disease. Interestingly, the clinical influence of DRB1*03 (good prognosis) dominated over that of DRB1*15 (bad prognosis).</p> <p>Conclusions</p> <p>We found several significant differences between LS and non-LS patients and we therefore suggest that genetic association studies in sarcoidosis should include a careful clinical characterisation and sub-grouping of patients, in order to reveal true genetic associations. This may be particularly accurate to do in the heterogeneous non-LS group of patients.</p
Lowest dimensional example on non-universality of generalized In\"on\"u-Wigner contractions
We prove that there exists just one pair of complex four-dimensional Lie
algebras such that a well-defined contraction among them is not equivalent to a
generalized IW-contraction (or to a one-parametric subgroup degeneration in
conventional algebraic terms). Over the field of real numbers, this pair of
algebras is split into two pairs with the same contracted algebra. The example
we constructed demonstrates that even in the dimension four generalized
IW-contractions are not sufficient for realizing all possible contractions, and
this is the lowest dimension in which generalized IW-contractions are not
universal. Moreover, this is also the first example of nonexistence of
generalized IW-contraction for the case when the contracted algebra is not
characteristically nilpotent and, therefore, admits nontrivial diagonal
derivations. The lower bound (equal to three) of nonnegative integer parameter
exponents which are sufficient to realize all generalized IW-contractions of
four-dimensional Lie algebras is also found.Comment: 15 pages, extended versio
Numerical Study of Length Spectra and Low-lying Eigenvalue Spectra of Compact Hyperbolic 3-manifolds
In this paper, we numerically investigate the length spectra and the
low-lying eigenvalue spectra of the Laplace-Beltrami operator for a large
number of small compact(closed) hyperbolic (CH) 3-manifolds. The first non-zero
eigenvalues have been successfully computed using the periodic orbit sum
method, which are compared with various geometric quantities such as volume,
diameter and length of the shortest periodic geodesic of the manifolds. The
deviation of low-lying eigenvalue spectra of manifolds converging to a cusped
hyperbolic manifold from the asymptotic distribution has been measured by
function and spectral distance.Comment: 19 pages, 18 EPS figures and 2 GIF figures (fig.10) Description of
cusped manifolds in section 2 is correcte
Expansion in perfect groups
Let Ga be a subgroup of GL_d(Q) generated by a finite symmetric set S. For an
integer q, denote by Ga_q the subgroup of Ga consisting of the elements that
project to the unit element mod q. We prove that the Cayley graphs of Ga/Ga_q
with respect to the generating set S form a family of expanders when q ranges
over square-free integers with large prime divisors if and only if the
connected component of the Zariski-closure of Ga is perfect.Comment: 62 pages, no figures, revision based on referee's comments: new ideas
are explained in more details in the introduction, typos corrected, results
and proofs unchange
Contractions of Low-Dimensional Lie Algebras
Theoretical background of continuous contractions of finite-dimensional Lie
algebras is rigorously formulated and developed. In particular, known necessary
criteria of contractions are collected and new criteria are proposed. A number
of requisite invariant and semi-invariant quantities are calculated for wide
classes of Lie algebras including all low-dimensional Lie algebras.
An algorithm that allows one to handle one-parametric contractions is
presented and applied to low-dimensional Lie algebras. As a result, all
one-parametric continuous contractions for the both complex and real Lie
algebras of dimensions not greater than four are constructed with intensive
usage of necessary criteria of contractions and with studying correspondence
between real and complex cases.
Levels and co-levels of low-dimensional Lie algebras are discussed in detail.
Properties of multi-parametric and repeated contractions are also investigated.Comment: 47 pages, 4 figures, revised versio
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