10,334 research outputs found
Families of Group Actions, Generic Isotriviality, and Linearization
We study families of reductive group actions on A2 parametrized by curves and show that every faithful action of a non-finite reductive group on A3 is linearizable, i.e. G-isomorphic to a representation of G. The difficulties arise for non-connected groups G. We prove a Generic Equivalence Theorem which says that two affine mor- phisms p: S â Y and q: T â Y of varieties with isomorphic (closed) fibers become isomorphic under a dominant Ìetale base change Ï : U â Y . A special case is the following result. Call a morphism Ï: X â Y a fibration with fiber F if Ï is flat and all fibers are (reduced and) isomorphic to F. Then an affine fibration with fiber F admits an Ìetale dominant morphism ÎŒ: U â Y such that the pull-back is a trivial fiber bundle: U ĂY X â U Ă F . As an application we give short proofs of the following two (known) results: (a) Every affine A1-fibration over a normal variety is locally trivial in the Zariski-topology; (b) Every affine A2-fibration over a smooth curve is locally trivial in the Zariski-topology
The NHS performance framework: taking account of economic behaviour
The provision of quantitative information has been given a key role in securing good performance in the new NHS. A new National Performance Framework has been proposed encompassing a number of dimensions of performance. Whilst this approach to managing the NHS is welcomed, it is essential to understand the strengths and limitations intrinsic to the use of performance indicators for this purpose. In particular, complex behavioural consequences may arise in response to the collection and dissemination of performance data, some of which may be unintended, potentially dysfunctional and damaging for the NHS. Results from a recent study on the performance of NHS Trusts are used to illustrate the sort of unintended side-effects which occur within the current system and which may in principle be replicated in the new system in future. Whilst the possibility of such consequences does not invalidate the potential of the new Performance Framework to secure the desired changes in the NHS, it does suggest that careful attention needs to be paid to the assessment of unanticipated side-effects.performance, NHS Trusts
A Solidification Phenomenon in Random Packings
We prove that uniformly random packings of copies of a certain
simply-connected figure in the plane exhibit global connectedness at all
sufficiently high densities, but not at low densities
Wage Labour Rates in Upper Canada, 1818-1840
Despite the heavy influx of immigrants into Upper Canada from 1815 to 1840, wage rates remained in general surprisingly stable. On the one hand, the range of rates offered to skilled tradesmen, such as carpenters and blacksmiths, narrowed with a gradual downward trend. Fluctuation over time of farm labourers' wages was less than variation due to distance from points of entry and seasonal employment. Day labourers' wages, on the other hand, seem to have actually increased marginally. Although female servants started with lower wages and saw the rate fall over time, male servants' wages rose to the general level of unskilled men's rates. These trends point to a steadier demand for male labour as the province became more heavily populated.
En dĂ©pit de lâafflux massif dâimmigrants venus sâĂ©tablir dans le Haut-Canada entre 1815 et 1840, la plupart des taux de salaires y sont demeurĂ©s Ă©tonnamment stables. Une grande partie des ouvriers qualifiĂ©s, tels les charpentiers et les forgerons, ont connu une rĂ©duction graduelle de lâĂ©ventail des salaires offerts. Par ailleurs, les salaires des ouvriers agricoles ont variĂ© davantage en fonction de lâĂ©loignement des points dâarrivĂ©e et des saisons que selon le cours des annĂ©es. Pour ce qui est des journaliers agricoles, leurs salaires semblent avoir augmentĂ© de façon marginale. Quant aux gages des domestiques masculins, ils se sont Ă©levĂ©s au niveau des salaires des ouvriers masculins non spĂ©cialisĂ©s, tandis que les gages des domestiques fĂ©minines, dĂ©jĂ moins Ă©levĂ©s au point de dĂ©part, se sont dĂ©tĂ©riorĂ©s avec le temps. Ces tendances laissent supposer que la demande de main-dâoeuvre masculine sâest rĂ©gularisĂ©e au fur et Ă mesure que la population augmentait
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