Simulating Ability: Representing Skills in Games

Throughout the history of games, representing the abilities of the various agents acting on behalf of the players has been a central concern. With increasingly sophisticated games emerging, these simulations have become more realistic, but the underlying mechanisms are still, to a large extent, of an ad hoc nature. This paper proposes using a logistic model from psychometrics as a unified mechanism for task resolution in simulation-oriented games

Mitochondria Exert a Negative Feedback on the Propagation of Intracellular Ca2+ Waves in Rat Cortical Astrocytes

We have used digital fluorescence imaging techniques to explore the interplay between mitochondrial Ca2+ uptake and physiological Ca2+ signaling in rat cortical astrocytes. A rise in cytosolic Ca2+ ([Ca2+]cyt), resulting from mobilization of ER Ca2+ stores was followed by a rise in mitochondrial Ca2+ ([Ca2+]m, monitored using rhod-2). Whereas [Ca2+]cyt recovered within ∼1 min, the time to recovery for [Ca2+]m was ∼30 min. Dissipating the mitochondrial membrane potential (Δψm, using the mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxy-phenyl-hydrazone [FCCP] with oligomycin) prevented mitochondrial Ca2+ uptake and slowed the rate of decay of [Ca2+]cyt transients, suggesting that mitochondrial Ca2+ uptake plays a significant role in the clearance of physiological [Ca2+]cyt loads in astrocytes. Ca2+ signals in these cells initiated either by receptor-mediated ER Ca2+ release or mechanical stimulation often consisted of propagating waves (measured using fluo-3). In response to either stimulus, the wave traveled at a mean speed of 22.9 ± 11.2 μm/s (n = 262). This was followed by a wave of mitochondrial depolarization (measured using tetramethylrhodamine ethyl ester [TMRE]), consistent with Ca2+ uptake into mitochondria as the Ca2+ wave traveled across the cell. Collapse of Δψm to prevent mitochondrial Ca2+ uptake significantly increased the rate of propagation of the Ca2+ waves by 50%. Taken together, these data suggest that cytosolic Ca2+ buffering by mitochondria provides a potent mechanism to regulate the localized spread of astrocytic Ca2+ signals

Barriers to evidence-based practice in primary care nursing - why viewing decision-making as a context is helpful

Aim: This paper reports a study examining the barriers associated with research knowledge transfer amongst primary care nurses in the context of clinical decision-making. Background: The research literature on barriers to nurses' use of research knowledge is characterized by studies that rely primarily on self-report data, making them prone to reporting biases. Studies of the barriers to evidence-based practice often fail to examine information use and behaviour in the context of clinical decision-making. Methods: A multi-site, mixed method, case study was carried out in 2001. Data were collected in three primary care organizations by means of interviews with 82 primary care nurses, 270 hours of non-participant observation and 122 Q-sorts. Nurses were selected using a published theoretical sampling frame. Between-methods triangulation was employed and data analysed according to the principles of constant comparison. Multiple linear regression was used to explore relationships between a number of independent demographic variables (such as length of clinical experience) and the dependent variable of nurses' perspectives on the barriers to their use of research knowledge. Results: Three perspectives on barriers to research information use emerged: the need to bridge the skills and knowledge gap for successful knowledge transfer; information formats need to maximize limited opportunities for consumption; and limited access in the context of limited time for decision-making and information consumption. Demographic variables largely failed to predict allegiance to any of the perspectives identified. Conclusions: Researchers should consider using decision-making as a contextual backdrop for exploring information use and behaviour, avoid relying solely on self-reported behaviour as data, and use a variety of research methods to provide a richer picture of information-related behaviour. Practice developers need to recognize that understanding the decisions to which research knowledge is to be applied should be a characteristic of any strategy to increase research uptake by nurses