31 research outputs found
Quivers of monoids with basic algebras
We compute the quiver of any monoid that has a basic algebra over an
algebraically closed field of characteristic zero. More generally, we reduce
the computation of the quiver over a splitting field of a class of monoids that
we term rectangular monoids (in the semigroup theory literature the class is
known as ) to representation theoretic computations for group
algebras of maximal subgroups. Hence in good characteristic for the maximal
subgroups, this gives an essentially complete computation. Since groups are
examples of rectangular monoids, we cannot hope to do better than this.
For the subclass of -trivial monoids, we also provide a semigroup
theoretic description of the projective indecomposables and compute the Cartan
matrix.Comment: Minor corrections and improvements to exposition were made. Some
theorem statements were simplified. Also we made a language change. Several
of our results are more naturally expressed using the language of Karoubi
envelopes and irreducible morphisms. There are no substantial changes in
actual result
Dust in Hot Environments: Giant Dusty Galactic Halos
I review some of the evidences for dust in the Local Bubble and in galactic
halos and show that a general mechanism based on radiation pressure is capable
of evacuating dust grains from regions dominated by massive star energy input
and thus originate huge dusty halos. A Monte Carlo/particle model has been
developed to study the dust dynamics above HII chimneys and the results, among
other findings, show that dust can travel several kpc away from the plane of
the parent galaxy. The cosmological implications of extragalactic dust are
briefly outlined.Comment: 10 pages, LaTeX (lamuphys.sty), 3 figures, IAU166, The Local Bubble
and Beyond, Highlight Tal