Pion broadening and low-mass dilepton production

We determine mass and transverse momentum spectra of dileptons produced in Pb+Au (158 GeV/u) collisions within a pion annihilation model. A fit to the data requires simultaneous mass reduction and broadening of the in-medium rho propagator. The introduction of a finite pion width, as required within self-consistent approaches to the interacting pion gas, further improves the agreement with the data.Comment: 11 pages, 5 figure

Birth, survival and death of languages by Monte Carlo simulation

Simulations of physicists for the competition between adult languages since 2003 are reviewed. How many languages are spoken by how many people? How many languages are contained in various language families? How do language similarities decay with geographical distance, and what effects do natural boundaries have? New simulations of bilinguality are given in an appendix.Comment: 24 pages review, draft for Comm.Comput.Phys., plus appendix on bilingualit

Ancient solutions in Lagrangian mean curvature flow

Ancient solutions of Lagrangian mean curvature flow in C^n naturally arise as Type II blow-ups. In this extended note we give structural and classification results for such ancient solutions in terms of their blow-down and, motivated by the Thomas-Yau Conjecture, focus on the almost calibrated case. In particular, we classify Type II blow-ups of almost calibrated Lagrangian mean curvature flow when the blow-down is a pair of transverse planes or, when n=2, a multiplicity two plane. We also show that the Harvey-Lawson Clifford torus cone in C^3 cannot arise as the blow-down of an almost calibrated Type II blow-up.Comment: 30 pages, v2: minor typos corrected, accepted in Ann. Sc. Norm. Super. Pisa Cl. Sc

Partial normalizations of coxeter arrangements and discriminants

We study natural partial normalization spaces of Coxeter arrangements and discriminants and relate their geometry to representation theory. The underlying ring structures arise from Dubrovin’s Frobenius manifold structure which is lifted (without unit) to the space of the arrangement. We also describe an independent approach to these structures via duality of maximal Cohen–Macaulay fractional ideals. In the process, we find 3rd order differential relations for the basic invariants of the Coxeter group. Finally, we show that our partial normalizations give rise to new free divisors

Perceived risk and the marginal value of safety.

[Dataset available: http://hdl.handle.net/10411/15662]

Matching Grants and Charitable Giving: Why People Sometimes Provide a Helping Hand to Fund Environmental Goods

Matching grants are a prevalent mechanism for funding environmental, conservation, and natural resource projects. However, economists have largely been silent regarding the potential benefits of these mechanisms at increasing voluntary contributions. To examine the behavioral responses to different match levels, this research uses controlled laboratory experiments with generically framed instructions and introduces a general-form matching-grant mechanism, referred to as the proportional contribution mechanism (PCM). Results show that contributions are positively correlated with both the match and the induced value of the public good even when a dominant strategy is free-riding. An implication of this partial demand revelation result is that manifestations of this type of “helping hand†social preference should be counted in benefit-cost analysis.matching grants, public goods, charitable giving, voluntary contributions, experimental economics, warm glow, helping hand, Environmental Economics and Policy, Public Economics,

Status-Quo-Bias and Voluntary Contributions: Can Lab Experiments Parallel Real World Outcomes for Generic Advertising?

Many commodities have programs assessing producers for generic advertising. Ads such as "Got Milk?" and the "Incredible Edible Egg" are a public good for producers. Most of these programs originally used the Voluntary Contribution Mechanism, but have now become mandatory because of free-riding. This research simulates both the economic and psychological details of the egg industry in experiments that produce strikingly realistic results. Because mandatory programs have recently been declared unconstitutional, we also the test the Provision Point Mechanism and show that observed low levels of free-riding for both mechanisms are the result of status quo bias.Marketing, H40, H41, M37,

ALTERNATIVE AUCTION INSTITUTIONS FOR ELECTRIC POWER MARKETS

Restructuring of electric power markets is proceeding across the United States and in many other nations around the world. The performance of these markets will influence everything from the prices faced by consumers to the reliability of the systems. The challenges of these changes present many important areas for research. For much of the northeastern United States, restructuring proposals include, at least for the short term, the formation of a single-sided auction mechanism for the wholesale market. This research uses experimental methods to analyze how these markets may function. In the experiments, the two basic uniform price auction rules are tested under three different market sizes. Early experimental results suggest the commonly proposed last-accepted-offer auction works well, but market power could be a real concern.Resource /Energy Economics and Policy,

CAN HYPOTHETICAL, QUESTIONS PREDICT ACTUAL, PARTICIPATION IN PUBLIC PROGRAMS? A FIELD VALIDITY TEST USING A PROVISION POINT MECHANISM

Niagara Mohawk Power Corporation utilized a demand revealing public good mechanism to implement a green electricity program for provision of renewable energy and planting trees. This GreenChoiceTM program provided an opportunity to test the reliability of contingent valuation for predicting actual participation levels. In this study, participation levels predicted by hypothetical open-ended and dichotomous choice questions are compared to a reference level obtained from the actual GreenChoiceTM program. This approach represents an important improvement over past public goods contingent valuation validity tests which have relied on voluntary contribution mechanisms to elicit actual willingness to pay, and thus are likely to overestimate hypothetical bias because of free riding. Yet, even with a demand revealing mechanism and controlling for awareness, hypothetical participation levels obtained from dichotomous choice responses are found to significantly exceed actual contributions. In contrast, open-ended responses predict actual contribution levels, in that hypothetical open-ended responses are not significantly different from actual responses. Calibration of hypothetical responses is also explored.Public Economics, Resource /Energy Economics and Policy,