Mathematical Model of Ship Collision Probability

A mathematical model for estimating the probability of collision of ships passing through a uniform channel is proposed. The model takes into account the give-way motions of the encountered ships and the wake position characteristics under the given channel conditions such as width, length and centerline like buoys. The probability of collision is defined as the probability of an event where a ship fails to give way. Using this probability of collision, the “Collision Risk of Channel” is defined. The proposed model is examined by the collision statistics of some channels and straits in Japan. According to these statistics, the present model gives a good estimation of the collision risk of a channel. Since the proposed model takes account of traffic characteristics such as traffic volume, ship size distribution, and sailing velocity distribution, as well as channel conditions such as width, length and centerline mark like buoys, the effects of their change or control on the probability of collision can be easily predicted. Therefore, the proposed model is quite useful for the engineering planning and design of any channel

Reduced Nogo-P3 in adults with developmental coordination disorder (DCD)

Nogo-N2 is associated with the premotor cognitive process that precedes motor response (e.g., conflict monitoring), whereas Nogo-P3 is related to the inhibition of the actual motor response. We examined the influence of motor clumsiness of developmental coordination disorder (DCD) on components of the event-related potential in a Go/Nogo task. Participants were healthy adults (N = 81) that were classified into control and DCD groups based on the Movement Assessment Battery for Children Second Edition. We manipulated the difficulty in stopping a response by varying the frequency of Nogo stimuli in a response task into rare (20%) and frequent (80%) conditions, and Nogo-N2 and Nogo-P3 were calculated from electroencephalograms (EEGs) during the Go/Nogo tasks. The commission error rate in the rare condition was significantly higher in the DCD group than in the control group, indicating that motor clumsiness decreases task performance. There were no differences in Nogo-N2 between DCD and control groups. However, Nogo-P3 in the rare condition was reduced in the DCD group compared to the control group. These results suggest that the influence of motor clumsiness is limited to the cognitive process after the initiation of the actual motor response.Peer reviewe