Foliations with few non-compact leaves

Let F be a foliation of codimension 2 on a compact manifold with at least one non-compact leaf. We show that then F must contain uncountably many non-compact leaves. We prove the same statement for oriented p-dimensional foliations of arbitrary codimension if there exists a closed p form which evaluates positively on every compact leaf. For foliations of codimension 1 on compact manifolds it is known that the union of all non-compact leaves is an open set [A Haefliger, Varietes feuilletes, Ann. Scuola Norm. Sup. Pisa 16 (1962) 367-397].Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol2/agt-2-12.abs.htm

Baseline Cold Matter Effects on J/psi Production in AA Collisions

We present baseline calculations of initial-state shadowing and final-state absorption effects on J/psi production in nucleus-nucleus collisions at the Relativistic Heavy Ion Collider. We show predictions for Au+Au and Cu+Cu collisions at \sqrt{S_{NN}}=200 GeV and Cu+Cu collisions at \sqrt{S_{NN}} = 62 GeV as a function of the rapidity, y, and the number of binary nucleon-nucleon collisions, N_{\rm coll}.Comment: 7 pages, 4 figures, uses hiph-art.sty, one figure replaced, some corrections to tex

Phenomenology of Charm and Bottom Production

We discuss the renormalization and factorization scale dependence of charm and bottom production both at fixed-target energies and at present and future colliders. We investigate whether distributions calculable at leading order can be extrapolated to next-to-leading order by a constant multiplicative factor.Comment: 18 pages, 10 Postscript figures, compressed and uuencoded, included in a separate file or available from the author. To be published in Z. Phys.

Abelian varieties isogenous to a power of an elliptic curve over a Galois extension

Given an elliptic curve $E/k$ and a Galois extension $k'/k$, we construct an exact functor from torsion-free modules over the endomorphism ring ${\rm End}(E_{k'})$ with a semilinear ${\rm Gal}(k'/k)$ action to abelian varieties over $k$ that are $k'$-isogenous to a power of $E$. As an application, we show that every elliptic curve with complex multiplication geometrically is isogenous over the ground field to one with complex multiplication by a maximal order.Comment: 6 pages, added reference

Are We All Scientific Experts Now

Book review of Harry Collins book 'Are we all scientific experts now?

Anchoring symbols to sensorimotor control

This paper investigates how robots may emerge a lexicon to communicate complex meanings about actions such as `I am going to the red target' using simple (one-word) utterances. The main issue of the paper concerns the way these complex meanings represent the actions that are performed. It is argued that the meaning of these utterances may be represented without the need for categorising a complex flow of sensorimotor data. To illustrate the point, a simulation is presented in which robots develop such a communication system. The paper concludes by confirming that it is well possible to construct such a lexicon once robots have a number of basic sensorimotor skills available

How fast should we innovate?

The role of speed in innovations needs to be explored more thoroughly. I advocate here that for innovations which rely on scarce materials, research into more abundant substitutes needs to be accelerated while a regulatory-driven extension of the product life should slow down the number of incremental innovations and reduce our overall footprint on scarce resources. Chemical elements need to be established as global commons whose overuse can be regulated if required. Part of the efficiency gains of innovations could be used for research to offset the ‘rebound effect’ and provide the public with a return on early infrastructure investments