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Sequencing contents is of great importance for instructional design within the teaching planning processes. We believe that it is key for a meaningful learning. Therefore, we propose to formally establish a partial order relation among the contents. We have chosen the binary relation "to be a prerequisite" for that purpose. We have applied this approach to the mathematical contents of the compulsory Secondary Education of the Spanish educational system and the information obtained has been modeled as a graph. The amount of contents considered (814) and the number of ordered pairs in the order relation considered (17,782) has produced a big graph. In order to work effectively with that amount of data, we have used software specialized in network analysis. More precisely, we have used the software packages Pajek and Gephi. This software, together with the use of techniques borrowed from graph theory, has allowed providing a tool for debugging curriculum developments (similar to rule based expert systems verification).

Introduction and Objectives: The optimum treatment for patients with ST-segment elevation acute myocardial infraction (AMI) is primary percutaneous coronary intervention (PCI), provided that the door-to-balloon time is less than 90 min. The aims of this study were to determine actual treatment times in our patients, to investigate the effect of different factors in reducing those times, and to evaluate the impact of any delay on prognosis., Methods: The study involved patients who underwent primary or rescue PCI at our center between January 2005 and October 2007. Treatment times, clinical and angiographic characteristics, and follow-up findings at 1 and 12 months were recorded prospectively., Results: Overall, 389 PCIs were performed: 361 primary and 28 rescue interventions. The median total duration of ischemia was 235 [interquartile range, 170-335] min. The median door-to-balloon time was 79 [53-104] min. The door-to-balloon time was shorter when the ambulance service was able to notify the on-duty cardiologist, who alerted the interventional cardiology team. The difference was 30 [60-90] min (P< .01). Patients who arrived at the emergency department by their own means had the longest door-to-balloon time (100 min vs. 74 min; P< .01). A door-to-balloon time >120 min was associated with higher mortality at 30 days; multivariate analysis showed a clearly increasing trend., Conclusions: The door-to-balloon time at our center was in line with current recommendations, with the time being markedly shorter for patients for whom the ambulance service was able to give advanced warning. A shorter time was associated with a trend towards lower 30-day mortality.