No abstract

The gradual transitions that are found between unsuccessful and successful shock strengths in percent success or dose-response curves suggest that defibrillation is a probabilistic phenomenon. This concept appears to be reinforced by the fact that a frequency distribution is observed in defibrillation threshold data and that a dose-response relationship is also obtained by integration of the frequency distribution. The purpose of this study was to investigate whether a deterministic threshold model (based on experimental results) could produce 1) gradual transitions in dose-response curves, and 2) a threshold frequency distribution for individual subjects. In the experimental phase of the study, a linear deterministic relationship was found between transthoracic threshold current and defibrillation episode number (other variables held constant) in pentobarbital-anesthetized dogs. The correlation coefficient for each dog was between 0.77 and 0.98 (P less than 0.01), and both positive and negative slopes were found. Based on these results, threshold current was modeled for computer simulation as a linear function of episode number. The model was thus purely deterministic with no random variability. For each simulated experiment, several parameters were varied: order of shocks (increment, decrement, random order), slope of threshold function, and percent error of the initial threshold. Several hundred computer simulations were performed to determine the effect of varying these parameters. In all cases, threshold-frequency distributions and sigmoidal dose-response curves with gradual transitions were produced. The results of this investigation demonstrate that the apparent probabilistic behavior of defibrillation can be produced by a deterministic relationship.

This article, "Post What? The Liminality of Multi-Racial Identity," argues that the successes and failures of 21st-century satire reveal the myth of post-raciality while simultaneously dismissing racial essentialism. I focus on three critical moments: the commercial success of Mat Johnson's Loving Day, a text and forthcoming television show that examines the shifting self-identities of mixed-race individuals; the inability of a potential love interest on the television series, Louie, to accept a black woman as the ex-wife of the titular protagonist's phenotypically white daughters; and Barack Obama's self-designation as "black" on the census shortly after his election. I argue that the widespread reach of these instances, coupled with audience engagement and response, underscores the ways that the public realm frames a contemporary understanding of race as both meaningful and absurd.

The dispersion of hydroxyapatite, Ca 5 (PO 4 ) 3 OH, HAP, in aqueous systems in the presence of variety of polymers of different composition and ionic charge has been investigated. The dispersion data show that polymer effectiveness as HAP dispersant strongly depends upon polymer architecture. It has been found that anionic, non-ionic, amphoteric, and cationic surfactants are ineffective as HAP dispersants. Additionally, it has also been observed that cationic surfactant and cationic polymer exhibit antagonistic effect on the performance of anionic polymeric dispersants.