AEB effectiveness evaluation based on car-to-cyclist accident reconstructions using video of drive recorder

Objective: Though autonomous emergency braking (AEB) systems for car-to-cyclist collisions have been under development, an estimate of the benefit of AEB systems based on an analysis of accident data is needed for further enhancing their development. Compared to the data available from in-depth accident data files, data provided by drive recorders can be used to reconstruct car-to-cyclist collisions with greater accuracy because the position of cyclists can be observed from the videos. In this study, using data from drive recorders, the performance and limitations of AEB systems were investigated.

Method: Data of drive recorders involving taxi-to-cyclist collisions were collected. Using the images collected from the drive recorders of those taxis, 40 cases of 90° car-to-cyclist intersection collisions were reconstructed using PC-Crash. Then, the collisions were reconstructed again utilizing car models with AEB systems installed while changing the sensor’s field of view (FOV) and the delay time of initiating vehicle deceleration.

Results: The angle of FOV has a significant influence on avoiding car-to-cyclist collisions. Using a 50° FOV with a braking delay time of 0.5?s resulted in avoiding 6 collisions, and using a 90° FOV resulted in avoiding an additional 14 collisions. Even when installing an ideal AEB system providing 360° FOV and no delay time for braking, 8 collisions were not avoided, though the impact velocities were reduced for all of these remaining collisions. These collisions were caused by the cyclists’ sudden appearance in front of cars, and the time-to-collision (TTC) when the cyclists appeared was less than 0.9?s.

Conclusion: The AEB systems were effective for mitigating collisions that occurred due to driver perception delay. Because cyclists have a traveling velocity, a wide-angle FOV is effective for reduction of car-to-cyclist intersection collisions. The reduction of delay time in braking can reduce the number of collisions that are close to the braking performance limit. The collisions that remained even with an ideal AEB system in the PC-Crash simulation indicate that such collisions could still occur for autonomous cars if the traffic environment does not change.     

Fate estimation of estrogenic substances in an urban river by flux calculation.

This study investigated the fate of estrogenic substances in an urban river receiving discharge from wastewater treatment plants (WTPs) by flux calculation, focusing on the middle reaches of the Tama River in Tokyo, which is one of the most urbanized rivers in Japan. The level of estrogenic activity flux was almost negligibly small at the upstream station. The level was considerably raised after inflows from the WTPs and then the level declined in the lower reaches of the river. When contributions of estrogenic substances to estrogenic activity were estimated, estrone (E1) was the primary contributor to the total estrogenic activity in all the sampling stations, followed by estradiol (E2). The contribution of nonylphenol to estrogenic activity was small. The E1 and E2 accounted for approximately 90% or more of estrogenic activity in the Tama River. As for the total fluxes of the estrogenic substances in the study area in the Tama River, the proportion of flux associated with WTP discharge was approximately 100% of the total fluxes, and the effects of the tributaries flowing into the river were almost negligible. When the reduction ratios of estrogenic activity were calculated by the flux, the ratios were found to increase toward the lower reaches of the river. Similar changes were observed for E1. Meanwhile, the change of reduction ratios for E2 was different from that observed for estrogenic activity.     

Polybrominated diphenyl ethers and persistent organochlorines in Japanese human adipose tissues

The present study determined concentrations of polybrominated diphenyl ethers (PBDEs) and persistent organochlorines (OCs) in Japanese human adipose tissues collected during 2003–2004. Concentrations of PBDEs in adipose tissues were 1–2 orders of magnitude lower than those of OCs. However, observed PBDE congener levels in this study were relatively higher than those in Japanese human adipose tissues collected during 2000 reported previously, while OC levels were comparable to those in specimens collected during 1999 reported by our group. In addition, no age-dependent accumulation of PBDEs was observed, while OC levels except chlordane compounds increased with age. These results indicate recent human exposure to PBDEs in Japan. Among PBDE congeners accumulated in Japanese adipose tissues, BDE-153 was dominant, but this trend was different from those in human milk (BDE-47) and blood (BDE-209) reported previously in Japan, implying the congener-specific kinetics in human bodies. The significant positive correlations between PBDEs and OCs were observed in Japanese adipose tissues, indicating the similar exposure route of these contaminants for Japanese citizens, probably via fish intake.     

On illegal activities in the California state beverage container deposit system

One of the barriers to the effective use of a deposit-refund system is the burden borne by the system management actor, such as the government. The burden can be considered to increase if the system management actor collects unredeemed deposits which the system occasions. The deposit system of the state of California in the United States adopts this collection scheme to manage beverage containers. This article considers the burden of the system management actor by understanding the actual situation in the California beverage container deposit system. A variety of elements contributing to the burden was observed; however, the collection of unredeemed deposits is related to the suppression of illegal activities in the deposit system. Therefore, this article also considers the burden from the viewpoint of illegal activities and crackdowns. My conclusions with regard to the system management actor’s collection of unredeemed deposits are as follows: the collection requires that the right information regarding sales and returns be collected and the system management actor needs to verify whether the information is correct, e.g., by examining the business records of system participants.     

The Effect of Estrogens,River Water,and Treated Wastewater on Vitellogenin Induction of Japanese Medaka1

Abstract: The objective of this study is to evaluate the effect of estrogens on fish endocrine disruption in river water and treated wastewater. Endogenous estrogen estrone (E1), 17β‐estradiol (E2), river water, and treated wastewater were used for exposure tests on male Japanese medaka. Vitellogenin induction in male medaka was regarded as the endpoint of endocrine disruption. The effective concentrations of E1 and E2 on vitellogenin induction in medaka were evaluated by breeding medaka for 14 days in tanks with various concentrations of E1 or E2. Vitellogenin induction increased with elapse of time during exposure, with higher estrogen concentrations causing greater vitellogenin induction. According to the test results, the lowest observed effect concentrations (LOECs) of E1 and E2 were estimated to be 31.6 and 5.0 ng/l, respectively; and the E2 equivalent (EEQ) LOEC value of E1 was 5.2 ng‐E2/l, derived by multiplying the relative potency of E1 by that of E2 as estimated in this study. In continuous exposure tests using river water or treated wastewater, the estrogenic activity, an index of total estrogenic potential measured by yeast screen assay and expressed as EEQ, varied widely during the exposure tests, and significant vitellogenin induction was observed after several days of high levels of estrogenic activity in water. Vitellogenin concentration tended to significantly increase if EEQ exceeded the level of 5 ng‐E2/l. The threshold value was substantially the same as the results for E1 and E2 exposure tests of medaka. Consequently, EEQ over 5 ng‐E2/l was revealed to have the potential to cause endocrine disruption of male medaka. As estrogenic activity exceeding 5 ng‐E2/l was observed in some rivers in Japan, total estrogenic potential needs to be further decreased at wastewater treatment plants to prevent fish endocrine disruption.     

Trends in hazardous trace metal concentrations in aerosols collected in Beijing, China from 2001 to 2006

Daily observations of hazardous trace metal concentrations in aerosols in Beijing, China were made in the period from 2001 to 2006. We considered coal combustion as a major source of some anthropogenic metals by achieving a correlation analysis and by investigating enrichment factors and relative composition of metals. A possible extra source of some specific metals, such as Cu and Sb, was brake abrasion particles, however, we did not think the transport-related particle was a major source for the hazardous anthropogenic metals even though they could originate from vehicle exhaust and brake/tire abrasion particles. A time-trend model was used to describe temporal variations of chemical constituent concentrations during the five-year period. Several crustal elements, such as Al, Ti, V, Cr, Mn, Fe, and Co, did not show clear increases, with annual rates of change of -15.2% to 3.6%. On the other hand, serious increasing trends were noted from several hazardous trace metals. Cu, Zn, As, Cd, and Pb, which are derived mainly from anthropogenic sources, such as coal combustion, showed higher annual rate of change (4.9-19.8%, p<0.001) according to the regression model. In particular, the Cd and Pb concentrations increased remarkably. We hypothesize that the trend towards increasing concentrations of metals in the air reflects a change that has occurred in the process of burning coal, whereby the use of higher temperatures for coal combustion has resulted in increased emissions of these metals. The increasing use of low-rank coal may also explain the observed trends. In addition, nonferrous metal smelters are considered as a potential, albeit minor, reason for the increasing atmospheric concentrations of anthropogenic hazardous metals in Beijing city.     

Arsenic and Mn levels in Isaza (Gymnogobius isaza) during the mass mortality event in Lake Biwa, Japan

The present study measured the concentrations of 25 elements (Li, Mg, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, Pb and Bi) in the whole body of Isaza which is an endemic fish species to Lake Biwa, Japan, and compared the values in the specimens from the mass mortality Isaza (MMI) and normal fresh Isaza (NFI). The mean levels of Mn and total As (T-As) were relatively higher in MMI than in NFI. In the T-As, highly toxic inorganic As was detected in MMI. Moreover we found Mn and As concentrations in surface sediment were extremely high and temporally increased. From all these results, we could infer that the dissolution of Mn and As from surface sediment of Lake Biwa might have been one of the cause for the mass mortality of Isaza.     

Production of Poly(3-hydroxyalkanoate)s by Pseudomonas putida Cultivated in a Glycerol/Nonanoic Acid-Containing Medium

The biosynthesis of poly(3-hydroxyalkanoate) (PHA) by Pseudomonas putida (JCM6160) cultivated in a medium containing glycerol, nonanoic acid, or a glycerol/nonanoic acid mixture as the sole carbon sources was investigated. The PHA content was ~20 % when glycerol was the carbon source. This relatively low content can be attributed to the glycerol end-cap effect and the absence of enzymes that can directly synthesize PHA from acetyl CoA, which is the major metabolite of glycerol. Fatty acids, containing even numbered carbons, are synthesized from acetyl CoA, and they can be used as substrates for PHA synthesis. However, this process also results in decreasing PHA content as fatty acids are siphoned off into other pathways. However, addition of 5 mM nonanoic acid into a 20 mM glycerol-containing medium dramatically increased the PHA content in P. putida, which was 1.3 times larger than the sum of the values found when glycerol and nonanoic acid were each used as the sole carbon source. The PHA, synthesized in the glycerol/nonanoic acid medium, contains 3-hydroxy alkanoate units that have 5, 6, 7, 8, 9, or 10 carbons. The units that contain the even numbered carbons are derived from fatty acids that were produced from glycerol; whereas, the PHA units with the odd numbered carbons are derived from nonanoic acid. Pentanoate units were also found in the polyester derived from glycerol and nonanoic acid, and must have been synthesized indirectly via β-oxidation of nonanoic acid with the assistance of glycerol because pentanoate units were not found in PHA when P. putida was cultivated in the presence of only nonanoic acid.