The DØ experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DØ.

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Although most of the literature suggests that females are more cooperative than males, research on the Prisoner's Dilemma (PD) game has often found females more competitive. Analysis of the PD game suggests that the term "cooperation" has been used differently in that context than in other situations. Cooperation usually refers to a style of behavior characterized by fairness, equalit}', and sharing, while in the PD game it refers to one of two alternative choices. Other past research has indicated that males are primarily motivated to win in a competitive situation, while females are more concerned with interpersonal accommodation. Combining these two lines of research, it was predicted males'vvould make choices in the PD game in such a way as to maximize their winnings, while females would alter their choices on the basis of the social nature of the setting. Two PD game studies were undertaken in which, for half of the subjects, the cooperative response would lead to higher winnings, while for the remaining subjects the competitive choice was optimal. In the first study 40 subjects played with like-sex partners, while in the second study 80 subjects played with opposite-sex partners, whose physical attractiveness varied. Both studies found males more likely than females to make the optimal choice, while females were more likely to vary their choices as a function of the sex and attractiveness of their partner. The findings suggest that males and females do not have differential motives to cooperate, but respond to different cues.

In order to analyze data on joint charged-particle/photon distributions from an experimental search (T-864, MiniMax) for disoriented chiral condensate (DCC) at the Fermilab Tevatron collider, we have identified robust observables, ratios of normalized bivariate factorial moments, with many desirable properties. These include insensitivity to many efficiency corrections and the details of the modeling of the primary pion production, and sensitivity to the production of DCC, as opposed to the generic, binomial-distribution partition of pions into charged and neutral species. The relevant formalism is developed and tested in Monte-Carlo simulations of the MiniMax experimental conditions.

Two exploratory studies were conducted involving children's reports of parental behavior and parents' child-rearing and internal-external control (I-E) attitudes as antecedents of children's beliefs that the reinforcements they receive are a consequence of their own behavior (internals). Internals, as contrasted to those who believe that reinforcements tend to occur independently of their behavior (externals), reported their parents as showing less rejection, hostile control, and withdrawal of relations, and more positive involvement and consistent discipline. There were no direct relationships between children's I-E beliefs and parents' child-rearing and I-E attitudes. However, parents whose children had an I-E orientation similar to their own expressed less disciplinarian and more indulgent child-rearing attitudes than parents whose children had an I-E belief unlike their own. Parent-child I-E similarity may be mediated by nurturant, accepting parental behavior.

The purpose of this study was to evaluate the relative contributions of ankle and knee position to tension in the Achilles tendon and to determine whether there exists a position of plantarflexion at which the passive tensioning effect of knee extension is eliminated. Seven matched pairs of fresh-frozen cadaver lower extremities were tested. A buckle transducer was used to measure forces in the tendon throughout the full range of knee motion, with the hindfoot fixed. Positioning the hindfoot in 20 degrees to 25 degrees of plantarflexion effectively eliminates tension in the Achilles tendon, regardless of knee position. This information is directly applicable both to the nonoperative treatment of ruptures of the Achilles tendon employing a short leg cast and to surgical repairs, in which tension must be controlled precisely.

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