Using M∕M∕∞ Queueing Model in On-Street Parking Maneuvers

Abstract

This paper quantifies the influence badly parked vehicles and on-street parking maneuvers have on average link journey times as a function of the duration of the events and the number of designated maneuvers and flow, by applying an M / M / ϱ queueing model in which arrival and departure are all Poisson processes. The method has been validated using microsimulations calibrated by in-situ measurements taken in the streets of the city of Santander ͑Cantabria, Spain͒. The analysis on the delays shows a good fit for the M / M / ϱ model for flows of 60-70% of capacity where the error is always lower than 5%. This demonstrates the efficiency of the M / M / ϱ model for studying how on-street parking maneuvers and badly parked vehicles influence traffic flow and avoids the need to use generally more laborious microsimulation models. Microsimulations are used to calculate the reduction in link capacity for each case in the study and the increases in average journey times for the rest of the road users. This shows the effect that allowing on-street parking on arterial or main roads has on the rest of the traffic.

The use of sugar free chewing gum as a supplement in the prevention of dental caries. Narrative Review

“…The release of calcium and phosphate ions on the tooth surface causes a saturation of these elements on the enamel surface 22 , thus inhibiting demineralization and remineralization. Amorphous calcium phosphate (ACP) is an ideal system to prevent tooth decay and achieve incipient lesions remineralization 16 .…”

“…It is considered cariostatic since it diminishes the counts of Streptococcus mutans (SM) 5,11,[23][24][25] , the formation of dental plaque 22 and, therefore, dental caries incidence. Therefore, it is particularly effective in those conditions under which it is not possible to make a proper oral hygiene 25 .…”

“…a state of oversaturation with respect to the enamel of the teeth, which reduces demineralization and promotes remineralization 22,39 .…”

“…5 can provide anticaries protection. It has been stipulated that chewing gum sweetened with xylitol from three to five times a day, for a minimum time of five minutes, ideally after food intake, is effective to achieve the desired effect on cariogenic bacteria 5,21,22 .…”

“…Casein is a protein derived from milk 22,39 . It can stabilize ACP that is located in the medium 22 , substantially increasing calcium phosphate level in dental plaque.…”