Evaluation of World Wide Web-based Lessons for a First Year Dental Biochemistry Course

First year dental students at The University of Texas Dental Branch at Houston (Dental Branch) are required to take a basic biochemistry course. To facilitate learning and allow student self-assessment of their progress, WWW-based lessons covering intermediary metabolism were developed as a supplement to traditional lectures. Lesson design combined text, graphics, and animations and included learner control, links to other learning resources, and practice exercises and exams with immediate feedback. Results from an on-line questionnaire completed by students in two different classes showed that they completed 50% of the lessons and spent an average of 4 hrs. on-line. A majority of the students either agreed or strongly agreed that practice exercises were helpful, that the ability to control the pace of the lessons was important, that the lesson structure and presentation was easy to follow, that the illustrations, animations, and hyperlinks were helpful, and that the lessons were effective as a review. The very positive response to the WWW-based lessons indicates the usefulness of this approach as a study aid for dental students

A duality principle for selection games

A dinner table seats k guests and holds n discrete morsels of food. Guests select morsels in turn until all are consumed. Each guest has a ranking of the morsels according to how much he would enjoy eating them; these rankings are commonly known. A gallant knight always prefers one food division over another if it provides strictly more enjoyable collections of food to one or more other players (without giving a less enjoyable collection to any other player) even if it makes his own collection less enjoyable. A boorish lout always selects the morsel that gives him the most enjoyment on the current turn, regardless of future consumption by himself and others. We show the way the food is divided when all guests are gallant knights is the same as when all guests are boorish louts but turn order is reversed. This implies and generalizes a classical result of Kohler and Chandrasekaran (1971) about two players strategically maximizing their own enjoyments. We also treat the case that the table contains a mixture of boorish louts and gallant knights. Our main result can also be formulated in terms of games in which selections are made by groups. In this formulation, the surprising fact is that a group can always find a selection that is simultaneously optimal for each member of the group.Comment: 8 pages, 2 figure

Comparison of approximate and numerical analyses of nonlinear combustion instability

At the present time, there are three general analytical techniques available to study problems of unsteady motions in rocket motors: linear stability analysis; approximate nonlinear analysis, founded on examining the behavior of coupled normal modes; and numerical calculations based on the conservation equations for one-dimensional flows. The last two yield the linear results as a limit. It is the main purpose of this paper to check the accuracy of the approximate analysis against the numerical analysis for some special cases. The results provide some justification for using the approximate analysis to study three dimensional problems

Condensation and coexistence in a two-species driven model

Condensation transition in two-species driven systems in a ring geometry is studied in the case where current-density relation of a domain of particles exhibits two degenerate maxima. It is found that the two maximal current phases coexist both in the fluctuating domains of the fluid and in the condensate, when it exists. This has a profound effect on the steady state properties of the model. In particular, phase separation becomes more favorable, as compared with the case of a single maximum in the current-density relation. Moreover, a selection mechanism imposes equal currents flowing out of the condensate, resulting in a neutral fluid even when the total number of particles of the two species are not equal. In this case the particle imbalance shows up only in the condensate

Stars in the USNO-B1 Catalog with Proper Motions Between 1.0 and 5.0 arcseconds per year

This paper examines a subset of objects from the USNO-B1 catalogue with listed proper motions between 1.0 and 5.0 arcseconds per year. We look at the degree of contamination within this range of proper motions, and point out the major sources of spurious high proper motion objects. Roughly 0.1% of the objects in the USNO-B1 catalogue with listed motions between 1.0 and 5.0 arcseconds per year are real. Comparison with the revised version of Luyten's Half Second catalogue indicates that USNO-B1 is only about 47% complete for stars in this range. Preliminary studies indicate that there may be a dip in completeness in USNO-B1 for objects with motions near 0.1 arcseconds per year. We also present two new stars with motions between 1.0 and 5.0 arcseconds per year, 36 new stars with confirmed motions between 0.1 and 1.0 arcseconds per year, several new common proper motion pairs, and the recovery of LHS237a (VBs3).Comment: 42 pages, 16 figures, uses AASTeX v5.2, accepted by A