446 research outputs found
The quadratic isoperimetric inequality for mapping tori of free group automorphisms II: The general case
If F is a finitely generated free group and \phi is an automorphism of F then
the mapping torus of \phi admits a quadratic isoperimetric inequality.
This is the third and final paper in a series proving this theorem. The first
two were math.GR/0211459 and math.GR/0507589.Comment: 73 page
Actions of higher-rank lattices on free groups
If is a semisimple Lie group of real rank at least 2 and is an
irreducible lattice in , then every homomorphism from to the outer
automorphism group of a finitely generated free group has finite image.Comment: 11 pages, no figures. Final version. To appear in Compositio Mat
On the algorithmic construction of classifying spaces and the isomorphism problem for biautomatic groups
We show that the isomorphism problem is solvable in the class of central
extensions of word-hyperbolic groups, and that the isomorphism problem for
biautomatic groups reduces to that for biautomatic groups with finite centre.
We describe an algorithm that, given an arbitrary finite presentation of an
automatic group , will construct explicit finite models for the skeleta
of and hence compute the integral homology and cohomology of
.Comment: 21 pages, 4 figure
Absolute profinite rigidity and hyperbolic geometry
We construct arithmetic Kleinian groups that are profinitely rigid in the
absolute sense: each is distinguished from all other finitely generated,
residually finite groups by its set of finite quotients. The Bianchi group
with is rigid in
this sense. Other examples include the non-uniform lattice of minimal co-volume
in and the fundamental group of the Weeks manifold
(the closed hyperbolic -manifold of minimal volume).Comment: v2: 35 pages. Final version. To appear in the Annals of Mathematics,
Vol. 192, no. 3, November 202
Commensurations of and its Torelli subgroup
For , the abstract commensurators of both and
its Torelli subgroup are isomorphic to
itself.Comment: 29 pages, 5 figure
Diacetyl in Australian dry red wines and its significance in wine quality
The diacetyl content of 466 Australian dry red table wines ranged from less than 0.1 ppm to 7.5 ppm with a mean of 2.4 ppm. Malo-lactic fermentation had occurred in 71 per cent of the wines, which had a mean diacetyl level of 2.8 ppm. In wines which had not undergone malo-lactic fermentation the mean diacetyl level 1.3 ppm.Taste threshold tests showed that a difference of as little as 1 ppm could be detected in a light dry red wine containing 0.3 ppm diacetyl. In a full flavoured darker wine of higher quality containing 3 ppm the minimum detectable addition was 1.3 ppm.It is considered that diacetyl in amounts up to 2 to 4 ppm, depending on the wine, improved quality by adding complexity to the flavour. Above these levels the aroma of diacetyl became identifiable as such and resulted in a reduction in quality. The diacetyl content of a range of red table wines stored at 15° C showed a mean decrease of 19 per cent in diacetyl content in 4 months, 22 per cent in 8 months, 26 per cent in 12 months and 28 per c ent in 18 months
Peripheral separability and cusps of arithmetic hyperbolic orbifolds
For X = R, C, or H it is well known that cusp cross-sections of finite volume
X-hyperbolic (n+1)-orbifolds are flat n-orbifolds or almost flat orbifolds
modelled on the (2n+1)-dimensional Heisenberg group N_{2n+1} or the
(4n+3)-dimensional quaternionic Heisenberg group N_{4n+3}(H). We give a
necessary and sufficient condition for such manifolds to be diffeomorphic to a
cusp cross-section of an arithmetic X-hyperbolic (n+1)-orbifold. A principal
tool in the proof of this classification theorem is a subgroup separability
result which may be of independent interest.Comment: Published by Algebraic and Geometric Topology at
http://www.maths.warwick.ac.uk/agt/AGTVol4/agt-4-32.abs.htm
Assessing Competence of NHS Consultants: Challenges and Possible Solutions
Even a mention of formal assessment of senior clinicians can be a contentious issue, to say least, when revalidation is said to be firmly in place in NHS-UK for almost half a decade. Since revalidation is accepted as a standard modality of assessment of performance, some colleagues in NHS wonder ‘stir up a hornets’ nest,’ when the authors allude to limitations of revalidation because poorly performing senior NHS clinicians may ‘slip through the net.’ NHS consultants have clinical as well as training roles. Fundamentally, this assessment (revalidation) is meant to ensure the safety of the public and mitigates the risk of disciplinary action by the GMC. Unfortunately, a disciplinary action is often the first sign of underperformance. In fact, the Bristol and Shipman inquiries have underscored the importance of the non-clinical and behavioural skills like communication, teamworking, personal organization and leadership are as important as clinical skills. Rather than considered an assessment tool, an annual appraisal is aimed to facilitate and improve the way NHS consultants work and provide services. The authors have to wait for five years, to assess the efficacy of the system that was introduced with much ‘fanfare’ since it was projected as a panacea for poor performance by ’bad doctors.’ The objectives of this article are to contextualize the issue of the underperformance among senior clinicians in the current NHS environment and to conceptualize the idea that their performance as trainers is directly related to their performance as clinicians. It is worth identifying the underlying factors of that are related to, or even better, can predict underperformance and will help evolve a strategy to help those consultants who are underperforming
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