397,871 research outputs found
Category equivalences involving graded modules over path algebras of quivers
Let kQ be the path algebra of a quiver Q with its standard grading. We show
that the category of graded kQ-modules modulo those that are the sum of their
finite dimensional submodules, QGr(kQ), is equivalent to several other
categories: the graded modules over a suitable Leavitt path algebra, the
modules over a certain direct limit of finite dimensional multi-matrix
algebras, QGr(kQ') where Q' is the quiver whose incidence matrix is the n^{th}
power of that for Q, and others. A relation with a suitable Cuntz-Krieger
algebra is established. All short exact sequences in the full subcategory of
finitely presented objects in QGr(kQ), split so that subcategory can be given
the structure of a triangulated category with suspension functor the Serre
degree twist (-1); it is shown that this triangulated category is equivalent to
the "singularity category" for the radical square zero algebra kQ/kQ_{\ge 2}.Comment: Several changes made as a result of the referee's report. Added Lemma
3.5 and Prop. 3.6 showing that O is a generato
Power and Practice in Academic Library Materials Selection Paradigms
This article examines the theoretical and practical implications of three methods of materials acquisitions in an academic library. First, it evaluates how traditional collection development, electronic patron driven acquisitions (PDA) and other older forms of PDA affect materials storage, preservation, purchase speed and usage. Then this paper employs Foucault’s theories about power to discuss the ramifications of these acquisitions methods for librarians and three major user groups: faculty, graduate students and undergraduates. The article concludes that each method presents different practical and theoretical advantages and disadvantages
DVCS with CLAS
Generalized parton distributions provide a unifying framework for the
interpretation of exclusive reactions at high . The most promising
reaction for the investigation of these distributions is the hard production of
photons using Deeply Virtual Compton Scattering (DVCS). This reaction can be
accessed experimentally by determining the production asymmetry using polarized
electrons on a proton target. Pioneering experiments with CLAS and HERMES have
produced the first measurements of this asymmetry. We will review the current
experimental program to study DVCS at Jefferson Lab. Recent high statistics
data taken with CLAS at 5.75 GeV allows us to determine this asymmetry at low
- in the valence region (=0.1-0.5) up to a of 4 GeV.Comment: 5 pages, 3 figures, Conference on the Intersections of Particle and
Nuclear Physics, New York City, May 19-24, 200
- …