Maximum expected survival rate model for public access defibrillator placement.

AIM: Mathematical optimization of automated external defibrillator (AED) placement has demonstrated potential to improve survival of out-of-hospital cardiac arrest (OHCA). Existing models mostly aim to improve accessibility based on coverage radius and do not account for detailed impact of delayed defibrillation on survival. We aimed to predict OHCA survival based on time to defibrillation and developed an AED placement model to directly maximize the expected survival rate. METHODS: We stratified OHCAs occurring in Singapore (2010-2017) based on time to defibrillation and developed a regression model to predict the Utstein survival rate. We then developed a novel AED placement model, the maximum expected survival rate (MESR) model. We compared the performance of MESR with a maximum coverage model developed for Canada that was shown to be generalizable to other settings (Denmark). The survival gain of MESR was assessed through 10-fold cross-validation for placement of 20 to 1000 new AEDs in Singapore. Statistical analysis was performed using χ2 and McNemar's tests. RESULTS: During the study period, 15,345 OHCAs occurred. The power-law approximation with R2 of 91.33% performed best among investigated models. It predicted a survival of 54.9% with defibrillation within the first two minutes after collapse that was reduced by more than 60% without defibrillation within the first 4 minutes. MESR outperformed the maximum coverage model with P-value < 0.05 (<0.0001 in 22 of 30 experiments). CONCLUSION: We developed a novel AED placement model based on the impact of time to defibrillation on OHCA outcomes. Mathematical optimization can improve OHCA survival.

Jamming transitions induced by an attraction in pedestrian flow.

We numerically study jamming transitions in pedestrian flow interacting with an attraction, mostly based on the social force model for pedestrians who can join the attraction. We formulate the joining probability as a function of social influence from others, reflecting that individual choice behavior is likely influenced by others. By controlling pedestrian influx and the social influence parameter, we identify various pedestrian flow patterns. For the bidirectional flow scenario, we observe a transition from the free flow phase to the freezing phase, in which oppositely walking pedestrians reach a complete stop and block each other. On the other hand, a different transition behavior appears in the unidirectional flow scenario, i.e., from the free flow phase to the localized jam phase and then to the extended jam phase. It is also observed that the extended jam phase can end up in freezing phenomena with a certain probability when pedestrian flux is high with strong social influence. This study highlights that attractive interactions between pedestrians and an attraction can trigger jamming transitions by increasing the number of conflicts among pedestrians near the attraction. In order to avoid excessive pedestrian jams, we suggest suppressing the number of conflicts under a certain level by moderating pedestrian influx especially when the social influence is strong.

A Concurrence of Adenocarcinoma with Micropapillary Features and Composite Glandular-Endocrine Cell Carcinoma in the Stomach.

We report a unique case of synchronous double primary gastric cancer consisting of adenocarcinoma components with micropapillary features and composite glandular-endocrine cell carcinoma components. The patient was a 53-year-old man presenting with a 6-month history of epigastric pain and diarrhea. A subtotal gastrectomy was performed. Histologically, one tumor was composed of micropapillary carcinoma components (50%) with tight clusters of micropapillary aggregates lying in the empty spaces, admixed with moderately differentiated adenocarcinoma components. MUC-1 was expressed at the stromal edge of the micropapillary component. The other tumor was composed of atypical carcinoid-like neuroendocrine carcinoma (50%), adenocarcinoid (30%), and adenocarcinoma components (20%). The neuroendocrine components were positive for CD56, synaptophysin, chromogranin, and creatine kinase. The adenocarcinoid components were positive for both carcinoembryonic antigen and neuroendocrine markers (amphicrine differentiation). This case is unique, due to the peculiar histologic micropapillary pattern and the histologic spectrum of adenocarcinoma adenocarcinoid-neuroendocrine carcinoma of the synchronous composite tumor.

Effects of Switching Behavior for the Attraction on Pedestrian Dynamics.

Walking is a fundamental activity of our daily life not only for moving to other places but also for interacting with surrounding environment. While walking on the streets, pedestrians can be aware of attractions like shopping windows. They can be influenced by the attractions and some of them might shift their attention towards the attractions, namely switching behavior. As a first step to incorporate the switching behavior, this study investigates collective effects of switching behavior for an attraction by developing a behavioral model. Numerical simulations exhibit different patterns of pedestrian behavior depending on the strength of the social influence and the average length of stay. When the social influence is strong along with a long length of stay, a saturated phase can be defined at which all the pedestrians have visited the attraction. If the social influence is not strong enough, an unsaturated phase appears where one can observe that some pedestrians head for the attraction while others walk in their desired direction. These collective patterns of pedestrian behavior are summarized in a phase diagram by comparing the number of pedestrians who visited the attraction to the number of passersby near the attraction. Measuring the marginal benefits with respect to the strength of the social influence and the average length of stay enables us to identify under what conditions enhancing these variables would be more effective. The findings from this study can be understood in the context of the pedestrian facility management, for instance, for retail stores.

Collective dynamics of pedestrians interacting with attractions.

In order to investigate collective effects of interactions between pedestrians and attractions, this study extends the social force model. Such interactions lead pedestrians to form stable clusters around attractions, or even to rush into attractions if the interaction becomes stronger. It is also found that for high pedestrian density and intermediate interaction strength, some pedestrians rush into attractions while others move to neighboring attractions. These collective patterns of pedestrian movements or phases and transitions between them are systematically presented in a phase diagram. The results suggest that safe and efficient use of pedestrian areas can be achieved by moderating the pedestrian density and the strength of attractive interaction, for example, in order to avoid situations involving extreme desire for limited resources.

An ASIC design for versatile receive front-end electronics of an ultrasonic medical imaging system--16 channel analog inputs and 4 dynamically focused beam outputs.

An ultra large-scale ASIC is designed for the receive front-end electronics of an ultrasonic medical imaging system. The chip receives 16 channel analog rf signals and outputs 4 sets of sample-point-wise dynamically focused partial beam data. Four complete beam data sets are obtained in parallel by simply cascading as many chips as needed in an array system. High resolution of the focusing delay is obtained by nonuniformly selecting each channel data from a quadruply-interpolated rf data stream. The proposed ASIC can be applied to most practical array transducers in the frequency range of 2 to 10 MHz. The digital part of the designed ASIC can be implemented on a chip area of 17.9 microm2 with 0.18 mm CMOS technology, leaving sufficient room for 16 ADCs of 8 bits, 50 MHz on the 5.7 mm x 5.7 mm chip with a 208 pin package.