Caustics of plane curves, their birationality and matrix projections

After recalling the notion of caustics of plane curves and basic equations, we first show the birationality of the caustic map for a general source point S in the plane. Then we prove more generally a theorem for curves D in the projective space of 3x3 symmetric matrices B. For a general 3x1 vector S the projection to the plane given by B --- BS is birational on D, unless D is not a line and D is contained in a plane of the form Delta_v = {B | Bv = 0}.Comment: 10 pages, to appear in a Springer Verlag volume dedicated to Klaus Hulek on the occasion of his 60-th birthday. Final version, added some remarks by the refere

University Students Promoting Science in the Community

Project SEARCH (Science Education and Research for Children) has brought these undergraduate students here today. It is an outreach program designed to bring the science resources of a large research university to classrooms and community centers. For the past 9 years, SEARCH students have spent 4 hours each week doing hands-on-science experiments, dissecting frogs, demonstrating microscopes, lecturing about the planets, playing computer games, exploring the World Wide Web, and creating Web pages.published or submitted for publicationis peer reviewe

Sextonians and the magic square

Associated to any complex simple Lie algebra is a non-reductive complex Lie algebra which we call the intermediate Lie algebra. We propose that these algebras can be included in both the magic square and the magic triangle to give an additional row and column. The extra row and column in the magic square correspond to the sextonions. This is a six-dimensional subalgebra of the split octonions which contains the split quaternions

Computing Optimal Descriptions for Optimality Theory Grammars with Context-Free Position Structures

This paper describes an algorithm for computing optimal structural descriptions for Optimality Theory grammars with context-free position structures. This algorithm extends Tesar's dynamic programming approach [Tesar 1994][Tesar 1995] to computing optimal structural descriptions from regular to context-free structures. The generalization to context-free structures creates several complications, all of which are overcome without compromising the core dynamic programming approach. The resulting algorithm has a time complexity cubic in the length of the input, and is applicable to grammars with universal constraints that exhibit context-free locality.Comment: 7 pages, uses aclap.sty. To appear in ACL 199

Costs, outcomes, and cost-effectiveness of ovc interventions

This item is archived in the repository for materials published for the USAID supported Orphans and Vulnerable Children Comprehensive Action Research Project (OVC-CARE) at the Boston University Center for Global Health and Development.More than 1 out of every 10 children in sub-Saharan Africa and 1 out of 15 in Asia are orphans. A significant proportion of these children in sub-Saharan Africa were orphaned because one or both parents died from AIDS. Large numbers of other children are vulnerable to becoming orphans because one or both parents are HIV-infected. In response to the needs to children who are orphaned or made more vulnerable because of HIV/AIDS, the U.S. government through the U.S. President’s Emergency Plan for AIDS Relief (PEPFAR) spent about $1 billion during 2006-2008 on activities to improve the wellbeing of orphans and vulnerable children (OVC). Through the Reauthorization Act of 2008 (Lantos and Hyde. United States Global Leadership against HIV/AIDS, Tuberculosis, and Malaria Reauthorization Act of 2008. Public Law 110-293; July 30, 2008), significant sums will continue to be allocated to OVC programs between 2009 and 2013. Given the past and continuing magnitude of the U.S. public’s investment in PEPFAR-funded OVC programs, combined with several years of implementation experience, this report reviews existing literature addressing the costs, the impacts/outcomes, and cost-effectiveness of OVC programs/interventions.The USAID | Project SEARCH, Orphans and Vulnerable Children Comprehensive Action Research (OVC-CARE) Task Order, is funded by the U.S. Agency for International Development under Contract No. GHH-I-00-07-00023-00, beginning August 1, 2008. OVC-CARE Task Order is implemented by Boston University. The opinions expressed herein are those of the authors and do not necessarily reflect the views of the funding agency

Charm physics at Belle

This talk reviews an unrepresentative selection of Belle's open-charm and charmonium analyses, focussing on new developments and topics of interest to the DIS community. Highlights include an X(3872) analysis favoring J^PC = 1++, and the D0-D*0bar bound-state interpretation.Comment: 4 pages, 2 figures, talk presented at DIS'05, Madison, WI. v2: corrected a typo in the summar

Has Ambisonics come of age?

Ambisonics was developed in the 1970’s as a flexible, psycho-acoustically aware system1. Developed at the same time as Quadraphonics2, Ambisonics is an often mis-understood system that was far ahead of it’s time. Due to the ubiquity of surround sound equipment in modern computers and interest in live surround events becoming more widespread, is the time, finally, right for Ambisonics to come into its’ own? In this paper, the definition of what makes a system Ambisonic is clarified with reference made to the traditional energy and velocity vector theory, higher order systems and use in both the live and domestic environment. More recent developments by the author are discussed with respect to irregular Ambisonic decoder design (such as for the ITU 5.1 speaker array) and analysis using Head Related Transfer Function data showing the extra insight this can give into the performance of one, seemingly similar, decoder design over another. The freely available suite of VST plug-ins (comprising of decoders, panners and an Ambisonic reverb) created using this technology are also presented, with case studies of their use in student projects at the University of Derby