Changing the Course of AIDS: Peer Education in South Africa and Its Lessons for the Global Crisis

[Excerpted from the Foreward by Charles Deutsch, Sc.D.] David Dickinson asks the question: How can we inject into the busy, distracted, difficult lives of the least educated and poorest among us the opportunity, and eventually the habit, to think critically about their social norms and behaviors; that is, about how to keep themselves and their loved ones healthy in a terribly dangerous environment? The answer is: Purposefully, persistently, with system and intent, through judicious infiltration of the social networks people live and act in. It requires intensive, sustainable face-to-face social strategies in which trusted people listen to what is being said and believed, and respond with stories that are not only accurate but also memorable and credible, and can compete successfully with the myths and beliefs that support dangerous norms. In some settings, such as schools, churches, mosques, and sports programs, peer education can be structured and scheduled. In other contexts, such as most workplaces, it is more informal and impromptu, but with many predictable opportunities to be prepared for. It is the why, what, and how of these latter contexts that Dickinson so ably addresses. He is especially eloquent about the need to work below the surface and behind the scenes, where peer education has few rivals. He documents aspects of the struggle against AIDS that are not usually subject to disciplined scrutiny. He culls from the experiences and wisdom of hundreds of dedicated adult peer educators across South Africa, reconciling and contrasting their insights with theories that have been the basis of social strategies to contain and control new infection and test and treat those currently infected. This book rests on a confidence in horizontal learning and a respect for what people who don\u27t have much formal education can know and do for one another. Those beliefs are not widely and deeply owned by decision makers in the United States or South Africa. As we cast about for more realistic ways to approach prevention, and settle on strategies that help people think and talk together about what they believe and what they do, these insights into peer education at the workplace will remind us that we have the resources in our midst to change our conversations, our norms, and our behavior

Mediation, Walrasian Tatonement, and Negotiations as an Exchange Economy

Alternative dispute resolution (ADR) procedures, such as mediation and arbitration, are becoming increasingly used to help resolve disputes in a variety of arenas. Among ADR procedures, mediation is the most utilized yet least analyzed procedure. This article examines negotiations and dispute resolution using the tools of general equilibrium theory. Specifically, mediators function as the Walrasian auctioneers of exchange theory by altering trade-off rates among bargaining issues. In this way, mediators facilitate a process leading towards voluntary settlement. This idea of Walrasian mediation is supported by the literature on mediation and mediator techniques, and so this insight opens up mediation to much more rigorous economic analysis. Among the implications of this approach are: 1) successful mediation leads to Pareto efficient settlements; 2) non-neutral mediators—those with a stake in the outcome—can guide negotiators towards preferred outcomes by introducing resources into mediation; 3) mediation Pareto dominates arbitration for resolving disputes.

Improving games AI performance using grouped hierarchical level of detail

Computer games are increasingly making use of large environments; however, these are often only sparsely populated with autonomous agents. This is, in part, due to the computational cost of implementing behaviour functions for large numbers of agents. In this paper we present an optimisation based on level of detail which reduces the overhead of modelling group behaviours, and facilitates the population of an expansive game world. We consider an environment which is inhabited by many distinct groups of agents. Each group itself comprises individual agents, which are organised using a hierarchical tree structure. Expanding and collapsing nodes within each tree allows the efficient dynamic abstraction of individuals, depending on their proximity to the player. Each branching level represents a different level of detail, and the system is designed to trade off computational performance against behavioural fidelity in a way which is both efficient and seamless to the player. We have developed an implementation of this technique, and used it to evaluate the associated performance benefits. Our experiments indicate a significant potential reduction in processing time, with the update for the entire AI system taking less than 1% of the time required for the same number of agents without optimisation

Cash or Credit? The importance of reward medium and experiment timing in classroom preferences for fairness

The author conducts experiments examining fairness preferences (Andreoni and Miller, 2002) and compares cash versus extra credit points as the reward medium. Additionally, he explores the role that classroom experiment timing—over the course of a semester—can have on outcomes. The results show that subjects are just as rational, if not more so, when the motivation is class points rather than cash. Also, preference classifications show that subjects are significantly more likely to be Selfish (and less likely to be Utilitarian) when the experiment is conducted early in the academic semester. One possible explanation is that is that the ultimate value of an extra credit point is more uncertain early in the semester, thus leading risk-averse students to make more selfish experiment allocations.

The Effects of Beliefs versus Risk Preferences on Bargaining Outcomes

In bargaining environments with uncertain impasse outcomes (e.g., litigation or labor strike outcomes), there is an identification problem that confounds data interpretation. In such environments, the minimally acceptable settlement value from a risk-averse (risk-loving) but unbiased bargainer is empirically indistinguishable from what one could get with risk-neutrality and pessimism (optimism). This paper reports data from a controlled bargaining experiment where risk preferences and beliefs are both measured in order to assess their relative importance in bargaining outcomes. The average lab subject is risk-averse, yet optimistic, which is consistent with existing studies that examine each in isolation. I also find that the effects of optimism dominate those of risk-aversion. Optimistic bargainers are significantly more likely to dispute and have aggressive final bargaining positions. Dispute rates are not statistically affected by risk preferences, but there is some evidence that risk aversion leads to less aggressive bargaining positions and lower payoff outcomes. A key implication is that increased settlement rates are more likely achieved by minimizing impasse uncertainty (to limit the potential for optimism) rather than maximizing uncertainty (to weaken the reservation point of risk-averse bargainers), as has been argued in the dispute resolution literature.risk preference, optimism, bargaining, experiments

Work effort effects in the classical labor supply model

This paper considers an extension of the classical static labor-leisure choice model to allow for an on-the-job leisure choice. The key result is that an income-compensated wage increase, while theoretically increasing hours worked, will likely increase on-the-job leisure.

Rotational accelerations stabilize leading edge vortices on revolving fly wings

The aerodynamic performance of hovering insects is largely explained by the presence of a stably attached leading edge vortex (LEV) on top of their wings. Although LEVs have been visualized on real, physically modeled, and simulated insects, the physical mechanisms responsible for their stability are poorly understood. To gain fundamental insight into LEV stability on flapping fly wings we expressed the Navier–Stokes equations in a rotating frame of reference attached to the wing's surface. Using these equations we show that LEV dynamics on flapping wings are governed by three terms: angular, centripetal and Coriolis acceleration. Our analysis for hovering conditions shows that angular acceleration is proportional to the inverse of dimensionless stroke amplitude, whereas Coriolis and centripetal acceleration are proportional to the inverse of the Rossby number. Using a dynamically scaled robot model of a flapping fruit fly wing to systematically vary these dimensionless numbers, we determined which of the three accelerations mediate LEV stability. Our force measurements and flow visualizations indicate that the LEV is stabilized by the `quasi-steady' centripetal and Coriolis accelerations that are present at low Rossby number and result from the propeller-like sweep of the wing. In contrast, the unsteady angular acceleration that results from the back and forth motion of a flapping wing does not appear to play a role in the stable attachment of the LEV. Angular acceleration is, however, critical for LEV integrity as we found it can mediate LEV spiral bursting, a high Reynolds number effect. Our analysis and experiments further suggest that the mechanism responsible for LEV stability is not dependent on Reynolds number, at least over the range most relevant for insect flight (100<Re<14,000). LEVs are stable and continue to augment force even when they burst. These and similar findings for propellers and wind turbines at much higher Reynolds numbers suggest that even large flying animals could potentially exploit LEV-based force augmentation during slow hovering flight, take-offs or landing. We calculated the Rossby number from single-wing aspect ratios of over 300 insects, birds, bats, autorotating seeds, and pectoral fins of fish. We found that, on average, wings and fins have a Rossby number close to that of flies (Ro=3). Theoretically, many of these animals should therefore be able to generate a stable LEV, a prediction that is supported by recent findings for several insects, one bat, one bird and one fish. This suggests that force augmentation through stably attached (leading edge) vortices could represent a convergent solution for the generation of high fluid forces over a quite large range in size

Biofluiddynamic scaling of flapping, spinning and translating fins and wings

Organisms that swim or fly with fins or wings physically interact with the surrounding water and air. The interactions are governed by the morphology and kinematics of the locomotory system that form boundary conditions to the Navier–Stokes (NS) equations. These equations represent Newton's law of motion for the fluid surrounding the organism. Several dimensionless numbers, such as the Reynolds number and Strouhal number, measure the influence of morphology and kinematics on the fluid dynamics of swimming and flight. There exists, however, no coherent theoretical framework that shows how such dimensionless numbers of organisms are linked to the NS equation. Here we present an integrated approach to scale the biological fluid dynamics of a wing that flaps, spins or translates. Both the morphology and kinematics of the locomotory system are coupled to the NS equation through which we find dimensionless numbers that represent rotational accelerations in the flow due to wing kinematics and morphology. The three corresponding dimensionless numbers are (1) the angular acceleration number, (2) the centripetal acceleration number, and (3) the Rossby number, which measures Coriolis acceleration. These dimensionless numbers consist of length scale ratios, which facilitate their geometric interpretation. This approach gives fundamental insight into the physical mechanisms that explain the differences in performance among flapping, spinning and translating wings. Although we derived this new framework for the special case of a model fly wing, the method is general enough to make it applicable to other organisms that fly or swim using wings or fins

Nonbinding Suggestions: The Relative Effects of Focal Points versus Uncertainty Reduction on Bargaining Outcomes

This paper focuses on the effects of nonbinding recommendations on bargaining outcomes. Recommendations are theorized to have two effects: they can create a focal point for final bargaining positions, and they can decrease outcome uncertainty should dispute persist. While the focal point effect may help lower dispute rates, the uncertainty reduction effect is predicted to do the opposite for risk-averse bargainers. Which of these effects dominates is of critical importance in the optimal design of alternative dispute resolution (ADR) procedures, which are becoming increasingly utilized to help resolve disputes in a variety of settings. We theoretically examine the effects of recommendations on the bargaining contract zone. Our theoretical framework, which allows bargainers’ final positions to influence a binding outcome should negotiations fail, provides for a more stringent test of focal points than previously considered. We also present data from controlled laboratory bargaining experiments that are consistent with our model of recommendation effects. Recommendations are empirically shown to influence final bargaining positions and negotiated settlement values. Furthermore, dispute rates are significantly lower when one includes recommendations, even where the recommendation is completely ignored in final-stage arbitration. This highlights a potentially significant role for the use of nonbinding procedures, such as mediation, as a preliminary stage in developing more efficient ADR procedures.

The Equivalence of Panel Data Estimators under Orthogonal Experimental Design

This paper demonstrates the equivalence between pooled OLS, Fixed Effects, and Random Effects estimates when applied to data generated from an orthogonal experimental design under certain conditions. We show that the point estimates of the treatment effects are identical between these three panel data estimators but that the estimated standard errors differ. Specifically, the estimated variance covariance matrices are identical between FE and RE but differ from that of OLS. Despite the equivalence it is meaningful to test for OLS vs FE/RE because the error distributional assumptions are different.