A model of commodity money with minting and melting

We construct a random matching model of a monetary economy with commodity money in the form of potentially different types of silver coins that are distinguishable by the quantity of metal they contain. The quantity of silver in the economy is assumed to be fixed, but agents can mint and melt coins. Coins yield no utility, but can be traded. Uncoined silver yields direct utility to the holder. We find that optimal coin size increases with the probability of trade and with the stock of silver. We use these predictions of our model to analyze the coinage decisions of the monetary authorities in medieval Venice and England. Our model provides theoretical support for the view that decisions about coin sizes and types during the medieval period reflected a desire to improve the economic welfare of the general population, not just the desire for seigniorage revenue.

Coin sizes and payments in commodity money systems

Contemporaries, and economic historians, have noted several features of medieval and early modern European monetary systems that are hard to analyze using models of centralized exchange. For example, contemporaries complained of recurrent shortages of small change and argued that an abundance/dearth of money had real effects on exchange. To confront these facts, we build a random matching monetary model with two indivisible coins with different intrinsic values. The model shows that small change shortages can exist in the sense that adding small coins to an economy with only large coins is welfare improving. This effect is amplified by increases in trading opportunities. Further, changes in the quantity of monetary metals affect the real economy and the amount of exchange as well as the optimal denomination size. Finally, the model shows that replacing full-bodied small coins with tokens is not necessarily welfare improving.Coinage

Coin sizes and payments in commodity money systems

Commodity money standards in medieval and early modern Europe were characterized by recurring complaints of small change shortages and by numerous debasements of the coinage. To confront these facts, we build a random matching monetary model with two indivisible coins with different intrinsic values. The model shows that small change shortages can exist in the sense that changes in the size of the small coin affect ex ante welfare. Further, the optimal ratio of coin sizes is shown to depend upon the trading opportunities in a country and a country's wealth. Thus, coinage debasements can be interpreted as optimal responses to changes in fundamentals. Further, the model shows that replacing full-bodied small coins with tokens is not necessarily welfare-improving.Coinage

Unified connected theory of few-body reaction mechanisms in N-body scattering theory

A unified treatment of different reaction mechanisms in nonrelativistic N-body scattering is presented. The theory is based on connected kernel integral equations that are expected to become compact for reasonable constraints on the potentials. The operators T/sub +-//sup ab/(A) are approximate transition operators that describe the scattering proceeding through an arbitrary reaction mechanism A. These operators are uniquely determined by a connected kernel equation and satisfy an optical theorem consistent with the choice of reaction mechanism. Connected kernel equations relating T/sub +-//sup ab/(A) to the full T/sub +-//sup ab/ allow correction of the approximate solutions for any ignored process to any order. This theory gives a unified treatment of all few-body reaction mechanisms with the same dynamic simplicity of a model calculation, but can include complicated reaction mechanisms involving overlapping configurations where it is difficult to formulate models

Dominant partition method

By use of the L'Huillier, Redish, and Tandy (LRT) wave function formalism, a partially connected method, the dominant partition method (DPM) is developed for obtaining few body reductions of the many body problem in the LRT and Bencze, Redish, and Sloan (BRS) formalisms. The DPM maps the many body problem to a fewer body one by using the criterion that the truncated formalism must be such that consistency with the full Schroedinger equation is preserved. The DPM is based on a class of new forms for the irreducible cluster potential, which is introduced in the LRT formalism. Connectivity is maintained with respect to all partitions containing a given partition, which is referred to as the dominant partition. Degrees of freedom corresponding to the breakup of one or more of the clusters of the dominant partition are treated in a disconnected manner. This approach for simplifying the complicated BRS equations is appropriate for physical problems where a few body reaction mechanism prevails

Reinventing College Physics for Biologists: Explicating an epistemological curriculum

The University of Maryland Physics Education Research Group (UMd-PERG) carried out a five-year research project to rethink, observe, and reform introductory algebra-based (college) physics. This class is one of the Maryland Physics Department's large service courses, serving primarily life-science majors. After consultation with biologists, we re-focused the class on helping the students learn to think scientifically -- to build coherence, think in terms of mechanism, and to follow the implications of assumptions. We designed the course to tap into students' productive conceptual and epistemological resources, based on a theoretical framework from research on learning. The reformed class retains its traditional structure in terms of time and instructional personnel, but we modified existing best-practices curricular materials, including Peer Instruction, Interactive Lecture Demonstrations, and Tutorials. We provided class-controlled spaces for student collaboration, which allowed us to observe and record students learning directly. We also scanned all written homework and examinations, and we administered pre-post conceptual and epistemological surveys. The reformed class enhanced the strong gains on pre-post conceptual tests produced by the best-practices materials while obtaining unprecedented pre-post gains on epistemological surveys instead of the traditional losses.Comment: 35 pages including a 15 page appendix of supplementary material

Adjudication of Federal Causes of Action in State Court

The first section of this article considers the power of state courts to hear federal cases. Since it is now well established that state courts have the constitutional power to adjudicate federal causes of action if Congress so desires, the significant questions concern the method by which the judiciary is to decipher congressional intent. Although the courts have no difficulty where Congress has explicitly addressed the issue of state court jurisdiction, problems do arise in situations where Congress has remained silent on the question. The first section critically examines the traditional criteria employed by the courts for determining congressional intent in the face of congressional silence and then suggests a substantial alteration in the judiciary\u27s approach to the matter. The second section of the article considers the obligation of state courts to hear federal cases. After first evaluating constitutional questions surrounding such an obligation, this section wilI also examine difficult questions involving congressional intent-specifically, the circumstances under which Congress\u27 silence is intended to permit state courts to avoid hearing federal cases

Symbolic Manipulators Affect Mathematical Mindsets

Symbolic calculators like Mathematica are becoming more commonplace among upper level physics students. The presence of such a powerful calculator can couple strongly to the type of mathematical reasoning students employ. It does not merely offer a convenient way to perform the computations students would have otherwise wanted to do by hand. This paper presents examples from the work of upper level physics majors where Mathematica plays an active role in focusing and sustaining their thought around calculation. These students still engage in powerful mathematical reasoning while they calculate but struggle because of the narrowed breadth of their thinking. Their reasoning is drawn into local attractors where they look to calculation schemes to resolve questions instead of, for example, mapping the mathematics to the physical system at hand. We model the influence of Mathematica as an integral part of the constant feedback that occurs in how students frame, and hence focus, their work

Emerging technologies in physics education

Three emerging technologies in physics education are evaluated from the interdisciplinary perspective of cognitive science and physics education research. The technologies - Physlet Physics, the Andes Intelligent Tutoring System (ITS), and Microcomputer-Based Laboratory (MBL) Tools - are assessed particularly in terms of their potential at promoting conceptual change, developing expert-like problem-solving skills, and achieving the goals of the traditional physics laboratory. Pedagogical methods to maximize the potential of each educational technology are suggested.Comment: Accepted for publication in the Journal of Science Education and Technology; 20 page