Equilibria of point charges on convex curves

We study the equilibrium positions of three points on a convex curve under influence of the Coulomb potential. We identify these positions as orthotripods, three points on the curve having concurrent normals. This relates the equilibrium positions to the caustic (evolute) of the curve. The concurrent normals can only meet in the core of the caustic, which is contained in the interior of the caustic. Moreover, we give a geometric condition for three points in equilibrium with positive charges only. For the ellipse we show that the space of orthotripods is homeomorphic to a 2-dimensional bounded cylinder.Comment: minor correction

Pulsars in FIRST Observations

We identified 16 pulsars from the Faint Images of the Radio Sky at Twenty-cm (FIRST) at 1.4 GHz. Their positions and total flux densities are extracted from the FIRST catalog. Comparing the source positions with those in the PSRcatalog, we obtained better determined positions of PSRs J1022+1001, J1518+4904, J1652+2651, and proper motion upper limits of another three pulsars PSRs J0751+1807, J1012+5307, J1640+2224. Proper motions of the other 10 pulsars are consistent with the values in the catalog.Comment: 6 pages, 2 figures, 3 tables, submited to CJA

Three Business School Faculty Awarded Endowed Positions

Van Ness is Moore Scholar of Finance, Dibrell and Bush named Gresham and Roberts lecturers, respectivel

Boundary tastes at work: the gendered effect of authority positions in the workplace on taste in clothing and food

In this article, we test three hypotheses about the gendered effect of authority positions in the workplace on tastes in the areas of food and clothing. We use the micro-interactionist model of Randall Collins to formulate new hypotheses on the development of aesthetic and practical taste patterns, as described by Pierre Bourdieu. This leads to the following hypotheses: (1) people in superordinate positions will develop more aesthetic tastes; (2) men in subordinate positions will develop more practical tastes; and (3) women in subordinate positions will develop more aesthetic tastes. Our results show that there is a significant effect of being in a superordinate position on food preferences but not on clothing preferences. Among people in subordinate positions, women score higher than men on a fashion taste in clothing, lower on practical taste in clothing, and lower on a conventional taste in food

Memory for the meaningless: How chunks help

It is a classic result in cognitive science that chess masters can recall briefly presented positions better than weaker players when these positions are meaningful, but that their superiority disappears with random positions. However, Gobet and Simon (1996a) have recently shown that there is a skill effect with random chess positions as well. The impact of this result for theories of expert memory is discussed. CHREST, a computational, chunking model of chess expertise based on EPAM (Feigenbaum & Simon, 1984) accounts for this skill difference. The model is also compared with human data from an experiment where the role of presentation time for random positions was systematically varied from 1 second to 60 seconds. Simulations show that the model captures the main features of the human data, thus adding support to the EPAM theory. They also corroborate earlier estimates that visual short-term memory may contain three or four chunks