Bringing Packed Red Blood Cells to the Point of Combat Injury: Are We There Yet?

INTRODUCTION: Hemorrhage is the leading cause of injury related pre-hospital mortality. We investigated worst case scenarios and possible requirements of Turkish Military. As we plan to use blood resources during casualty transport, the impact of transport related mechanical stress on PRBC (packed red blood cell) were analyzed. MATERIAL AND METHODS: The in vitro experiment was performed in the environmental test laboratories of ASELSAN(R). Operational vibrations of potential casualty transport mediums such as Sikorsky Helicopters, Kirpi(R) Armoured Vehicle and NATO vibration standardsoftware MIL-STD-810G were recorded. The most powerful mechanical stress, which was created by the NATO standard, was applied to 15 units of fresh (7 day) PRBC in a blood cooler box. The vibrations were simulated by TDS v895 Medium-Force Shaker Device. On site blood samples were analyzed at 0, 6th and 24th hours for biochemical and biomechanical analyses. RESULTS: The mean age of fresh and old PRBCs was 4.9 (SD +/- 2.2) and 32.8 (SD +/- 11.8) days, respectively. Six-hour mechanical damage of fresh PRBC was demonstrated by increased erythrocyte fragmentation rates (p=0.015), hemolysis rates (p=0.003), supernatant potassium levels (p=0.003) and decreased hematocrit levels (p=0.015). Old PRBC hemolysis rates (p=0.015), supernatant potassium levels (p=0.015), supernatant Hb (p=0.015) were increased and Htc levels were decreased (p=0.015) within 6 hours. Two (%13) units of fresh and none of the old PRBC were eligible for transfusion after 6 hours of mechanical stress. CONCLUSION: When the austere combat environment was simulated for 24 hours, fresh and old PRBC hemolysis rates were above the quality criteria. Currently, a technology to overcome this mechanical damage does not seem to exist. In the light of the above data, a new national project is being performed

Existence and Computation of Equilibria in Games and Economies

In this dissertation we study the existence and computation of equilibria in games and economies. The results in this dissertation have been presented in the form of several papers, one of which have already been published. The first paper is entitled “Computation of Stationary Equilibrium Payoffs in Coalitional Bargaining.” In this paper, we provide an algorithm to compute the equilibrium payoffs in the coalitional bargaining model of Eraslan-McLennan (Journal of Economic Theory, 2013) by using recent developments in methods of numerical algebraic geometry. The Eraslan-McLennan model is a legisla- tive bargaining model which studies weighted voting games with players that are heterogeneous in their discount factors, voting weights and in terms of the probabilities of being selected as the proposer. Eraslan-McLennan characterizes the equilibria as fixed points of a set-valued function. In this paper, we show that the equilibria of the game can be characterized by solutions to a system of polynomial equations and provide an algorithm to compute the equilibrium payoffs. As an alternative approach, we show that all equilibria of such games can be characterized by fixed points of a continuous function, and use a variety of fixed point algorithms to execute this observation. These algorithms have implications for computing equilibria of dynamic models and should be useful in other applied work. The second paper is entitled “On the Nonemptiness of the α-core of Dis- continuous Games: Transferable and Nontransferable Utilities” (published in Journal of Economic Theory, 2015). The nonemptiness of the α-core of games with continuous payoff functions was proved by Scarf (1971) for nontransfer- able utilities and by Zhao (1999a) for transferable utilities. In this paper we present generalizations of their results to games with possibly discontinuous payoff functions. Our handling of discontinuity is based on Reny’s (1999) better- reply-security concept. We present examples to show that our generalizations are nonvacuous. The third paper is entitled “On the Nonemptiness of the Transferable Utility β-core of Discontinuous Games.” Zhao (1999) proved the nonemptiness of the transferable utility β-core of games with continuous payoff functions. In this paper we present generalizations of his result to games with possibly discontinuous payoff functions by applying the concepts and methods we introduced in the second paper. We rely on Reny’s (1999) concept of “better-reply-security” to handle any discontinuities that may arise. We present applications to show that our generalizations are nonvacuous. The fourth paper is entitled “On the Existence of Equilibrium with Discon- tinuous Preferences: Games and Economies.” In this paper, we present three fixed point theorems that can be seen as generalizations of the earlier works of Browder and Fan-Glicksberg and illustrate the use of these theorems as a ‘methodological toolkit’ for existence issues in a variety of economic settings. In particular, we present a synthetic treatment of the problem of the existence of an equilibrium in games and economies when the preferences of the individuals are not necessarily continuous or ordered. We also relate our results to those available in the antecedent literature

Welfare maximizing allocation without transfers

This paper studies welfare maximizing allocation of indivisible objects to ex-ante identical agents in the absence of monetary transfers. The agents, each with a unit demand, share a common ranking of the objects, and are privately informed about their own valuations. The structure of the optimal allocation policy depends on the agents’ relative valuation of the objects and the variation of this relative valuation across different types. When this variation is small, the required loss of welfare for eliciting agents’ private information exceeds its benefits. In this case, evenly randomized allocation is optimal. When this variation is significantly large, it is optimal to waste the less preferred object—not always allocate it to agents—to provide necessary incentives for information elicitation. The planner then uses this information to increase the frequency of allocating the more preferred object to the agent favored by the first best policy. Regardless of the size of the variation, it is never optimal to waste the more preferred object. We also propose an exchange game that implements the incentive efficient allocation