12,401 research outputs found
Towards a theory of local Shimura varieties
This is a survey article that advertizes the idea that there should exist a
theory of p-adic local analogues of Shimura varieties. Prime examples are the
towers of rigid-analytic spaces defined by Rapoport-Zink spaces, and we also
review their theory in the light of this idea. We also discuss conjectures on
the -adic cohomology of local Shimura varieties.Comment: 53 page
Mapping grid points onto a square forces an arbitrarily large Lipschitz constant
We prove that the regular square grid of points in the integer
lattice cannot be recovered from an arbitrary -element
subset of via a mapping with prescribed Lipschitz constant
(independent of ). This answers negatively a question of Feige from 2002.
Our resolution of Feige's question takes place largely in a continuous setting
and is based on some new results for Lipschitz mappings falling into two broad
areas of interest, which we study independently. Firstly the present work
contains a detailed investigation of Lipschitz regular mappings on Euclidean
spaces, with emphasis on their bilipschitz decomposability in a sense
comparable to that of the well known result of Jones. Secondly, we build on
work of Burago and Kleiner and McMullen on non-realisable densities. We verify
the existence, and further prevalence, of strongly non-realisable densities
inside spaces of continuous functions.Comment: 60 pages (43 pages of the main part, 13 pages of appendices), 10
figures. This is a revised version according to referees' comments. Our
version of the proof of the theorem about bilipschitz decomposition of
Lipschitz regular mappings was greatly simplified. To appear in GAF
Knowledge management in the voluntary sector: A focus on sharing project know-how and expertise
Voluntary sector organisations are operated principally by volunteers who are not obliged to share their knowledge, as might be expected in a for profit company, with a greater consequent loss of knowledge should individuals leave. This research examines how a volunteer-led organisation, the Campaign for Real Ale (CAMRA), acquires, stores and shares its project knowledge in the context of event management. Three annual CAMRA festivals of different sizes and maturity were selected to see how volunteers' knowledge is managed in the process of organising their festivals. Key festival officers were interviewed and focus groups, comprising of festival volunteers, were conducted. While the maturity of a festival and its size seemed to influence the ways in which knowledge was managed there were some commonalities between festivals. Evident was a strong master-apprentice model of learning with little formal training or record keeping except, that is, where legislation and accountability in treasury and health and safety functions were necessary. Trust between volunteers and their need to know and to share information appeared to be dependent, in part, on their perception and confidence in the success of the overarching project organisation, and this helped shape volunteers' knowledge sharing practices. Whilst there was evidence of a laissez-faire approach to codification and the sharing of knowledge, this was less so when volunteers recognised a genuine lack of knowledge which would hinder the success of their festival. The analysis also highlighted factors related to the sharing of knowledge that, it is suggested, have not been identified in the for-profit sector
Effects of screened Coulomb impurities on autoionizing two-electron resonances in spherical quantum dots
In a recent paper (Phys. Rev. B {\bf 78}, 075316 (2008)), Sajeev and Moiseyev
demonstrated that the bound-to-resonant transitions and lifetimes of
autoionizing states in spherical quantum dots can be controlled by varying the
confinment strength. In the present paper, we report that such control can in
some cases be compromised by the presence of Coulomb impurities. It is
demonstrated that a screened Coulomb impurity placed in the vicinity of the dot
center can lead to bound-to-resonant transitions and to avoided crossings-like
behavior when the screening of the impurity charge is varied. It is argued that
these properties also can have impact on electron transport through quantum dot
arrays
Allergen extracts and calcitriol affect IL-8 and TGF-β1 secretion in a cell line of canine oral keratinocytes
Retrofitting O'Raifeartaigh Models with Dynamical Scales
We provide a method for obtaining simple models of supersymmetry breaking,
with all small mass scales generated dynamically, and illustrate it with
explicit examples. We start from models of perturbative supersymmetry breaking,
such as O'Raifeartaigh and Fayet models, that would respect an symmetry if
their small input parameters transformed as the superpotential does. By
coupling the system to a pure supersymmetric Yang-Mills theory (or a more
general supersymmetric gauge theory with dynamically small vacuum expectation
values), these parameters are replaced by powers of its dynamical scale in a
way that is naturally enforced by the symmetry. We show that supersymmetry
breaking in these models may be straightforwardly mediated to the
supersymmetric Standard Model, obtain complete models of direct gauge
mediation, and comment on related model building strategies that arise in this
simple framework.Comment: 15 pages, harvmac bi
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