Using dynamic programming to determine an optimal strategy in a contract bridge tournament

One form of contract bridge tournament comprises several rounds of matches in which players compete as pairs for ‘masterpoints’ awarded for each match won or drawn and for being highly placed at the end of the tournament. In the second and subsequent rounds, pairs are matched against other pairs that have been approximately equally successful so far. There has been vague discussion among bridge players of the possible advantages of ‘throwing’, that is, deliberately losing a match in round r so as to obtain a lower ranking and face an easier opponent in round r+1. This paper uses dynamic programming and data from one tournament to identify an optimal strategy (either ‘throw’ or ‘play to win’). The optimal strategy is a function of a pair's ability, its placing after each round, the relative rewards for winning a match and finishing high, the opponent's skill, and the round. For example, we find that a very weak pair should ‘throw’ and ‘play to win’ in alternate rounds.     

SINGLET OXYGEN PRODUCTION BY SOME FUROCOUMARIN DERIVATIVES IN THE PRESENCE OF DNA: TIME RESOLVED LUMINESCENCE MEASUREMENTS

Abstract— The yield of singlet oxygen (¹Δ_g) from some furocoumarins in the presence of DNA has been measured using time resolved techniques. For both psoralen and 4'-aminomethyl-4,5',8-trimethylpsoralen, increasing DNA concentration leads to a decrease in the yield of singlet oxygen. In addition, there is a linear dependence between the yield of singlet oxygen and the observed triplet yield determined by laser flash photolysis. In view of this observation it seems unlikely that singlet oxygen production occurs from these two furocoumarins when they are complexed with DNA. Preliminary, albeit inconclusive, results for 8-methoxypsoralen are also presented.     

Remotely powered distributed microfluidic pumps and mixers based on miniature diodes

We demonstrate new principles of microfluidic pumping and mixing by electronic components integrated into a microfluidic chip. The miniature diodes embedded into the microchannel walls rectify the voltage induced between their electrodes from an external alternating electric field. The resulting electroosmotic flows, developed in the vicinity of the diode surfaces, were utilized for pumping or mixing of the fluid in the microfluidic channel. The flow velocity of liquid pumped by the diodes facing in the same direction linearly increased with the magnitude of the applied voltage and the pumping direction could be controlled by the pH of the solutions. The transverse flow driven by the localized electroosmotic flux between diodes oriented oppositely on the microchannel was used in microfluidic mixers. The experimental results were interpreted by numerical simulations of the electrohydrodynamic flows. The techniques may be used in novel actively controlled microfluidic-electronic chips.