25 research outputs found
Erratum
"Erratum on the article ‘A bi-level framework for pricing of high-occupancy toll lanes’." Transport, 29(4), p. 46
New Era of Air Quality Monitoring from Space: Geostationary Environment Monitoring Spectrometer (GEMS)
GEMS will monitor air quality over Asia at unprecedented spatial and temporal resolution from GEO for the first time, providing column measurements of aerosol, ozone and their precursors (nitrogen dioxide, sulfur dioxide and formaldehyde).
Geostationary Environment Monitoring Spectrometer (GEMS) is scheduled for launch in late 2019 - early 2020 to monitor Air Quality (AQ) at an unprecedented spatial and temporal resolution from a Geostationary Earth Orbit (GEO) for the first time. With the development of UV-visible spectrometers at sub-nm spectral resolution and sophisticated retrieval algorithms, estimates of the column amounts of atmospheric pollutants (O3, NO2, SO2, HCHO, CHOCHO and aerosols) can be obtained. To date, all the UV-visible satellite missions monitoring air quality have been in Low Earth orbit (LEO), allowing one to two observations per day. With UV-visible instruments on GEO platforms, the diurnal variations of these pollutants can now be determined. Details of the GEMS mission are presented, including instrumentation, scientific algorithms, predicted performance, and applications for air quality forecasts through data assimilation. GEMS will be onboard the GEO-KOMPSAT-2 satellite series, which also hosts the Advanced Meteorological Imager (AMI) and Geostationary Ocean Color Imager (GOCI)-2. These three instruments will provide synergistic science products to better understand air quality, meteorology, the long-range transport of air pollutants, emission source distributions, and chemical processes. Faster sampling rates at higher spatial resolution will increase the probability of finding cloud-free pixels, leading to more observations of aerosols and trace gases than is possible from LEO. GEMS will be joined by NASA's TEMPO and ESA's Sentinel-4 to form a GEO AQ satellite constellation in early 2020s, coordinated by the Committee on Earth Observation Satellites (CEOS)
Planning for Bus Rapid Transit in a Single Dedicated Bus Lane
Bus rapid transit (BRT) systems with dedicated lanes have shown advantages over traditional bus systems and have attracted more transit riders. However, it is not always possible to build BRT systems with double dedicated lanes because of physical and cost constraints. A BRT system with a single dedicated lane is more practical in such situations. In a single-lane configuration, buses approaching from opposite directions have to share the same road section and can overtake or pass each other only at the bus stops. An optimization model is proposed to describe the synchronization requirements of the BRT buses with the objective of minimizing the total travel and dwell time. The computational results show that a BRT system with a single dedicated lane yields total travel time that is similar to that of a BRT system with double dedicated lanes when the headway is not short (e.g., more than 20 min). In addition, to address possible delay at intersections, a simple speed control algorithm is implemented to adjust the bus speed in real time if the bus is delayed considerably. A microscopic simulation based on VISSIM is conducted to examine the impacts of the BRT bus on other traffic and the performance of the speed control. The simulation result shows that the speed control effectively handles the delay in the intersection and the other traffic is rarely affected by the speed control
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Evaluation of Cost-Effective Planning and Design Options for Bus Rapid Transit in Dedicated Bus Lanes
Bus Rapid Transit (BRT) systems with dedicated lanes have shown advantages over traditional bus systems and have attracted more transit riders. However, it is not always possible to build BRT systems with two dedicated lanes due to physical and cost constraints. A BRT system with a single dedicated lane is more practical and desirable in such situations. In a single lane configuration, buses approaching from opposite directions share the same road section and can overtake or pass each other only at the bus stops. We propose an optimization model to describe the synchronization requirements of the BRT buses with the objective to minimize the total travel and dwell time. The computational results show that a BRT system with a single dedicated lane yields similar total travel time to a BRT system with double dedicated lanes when the headway is not very short (e.g., more than 20 minutes). In addition, in order to manage the possible delay at intersections, a simple speed control algorithm is implemented to adjust the bus speed in real-time if the bus is delayed considerably. A microscopic simulation based on the simulation tool VISSIM is conducted to examine the impact of the BRT bus on other traffic and the performance of the speed control. The simulation result shows that the speed control effectively handles the delay at the intersection and that other traffic is rarely impacted by the speed control
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Improving Performance of Coordinated Signal Control Systems Using Signal and Loop Data
In this project, a traffic data collection system based-on the iDEN wireless network has been developed, lab tested and preliminarily tested in the field. The objective of the system is to provide a cost-effective and easy-to-maintain system that could still reliably provide traffic data over the wireless link.The project team developed an arterial performance measurement method that is based on the signal infrastructure data collected at PT2 Lab, U.C. Berkeley. The performance of the proposed model is illustrated by using a simulation study. The six-signal simulation network covers both heavily congested and light traffic intersections. The proposed model works well at both the intersection level and the arterial level. Estimation errors of travel time, number of stops and travel time reliability are insignificant.A general approach for robust signal optimization under demand uncertainty or flow fluctuations has been developed. The approach has been demonstrated in two different settings. The first one deals with the problem of synchronization of actuated signals along arterials along arterials. The other demonstration is to optimize the signal settings including the cycle length, green splits, offset points and phase sequences in an integrated manner, taking into account the day-to-day demand variations or uncertain further demand growth. The robust timing plans resulted from both models have been demonstrated in numerical tests to perform better against high-consequence scenarios without losing optimality in the average sense. Although the robust signal timing approach is applicable more widely, this report has been focused on timing models for pre-timed arterials
New Flavonolignan Glycosides from the Aerial Parts of Zizania latifolia
Two new flavonolignan glycosides, tricin-4\u27-O-(threo-β-guaiacylglyceryl) ether 7\u27\u27-O-β-D-glucopyranose (4) and tricin-4\u27-O-(erythro-β-guaiacylglyceryl) ether 7\u27\u27-O-β-D-glucopyranose (5) were isolated from the roots of Zizania latifolia, together with tricin-7-O-β-D-glucopyranose (1), tricin-4\u27-O-(threo-β-guaiacylglyceryl) ether 7-O-β-D-glucopyranose (2), and tricin-4\u27-O-(erythro-β-guaiacylglyceryl) ether 7-O-β-D-glucopyranose (3). Their structures were identified on the basis of spectroscopic techniques, including HR-ESI/MS, 1D-NMR (1H, 13C, DEPT), 2D-NMR (gCOSY, gHSQC, gHMBC), and IR spectroscopy
Wireless phototherapeutic contact lenses and glasses with red light-emitting diodes
Light-mediated therapeutics have attracted considerable attention as a method for the treatment of ophthalmologic diseases, such as age-related macular degeneration, because of their non-invasiveness and the effectiveness to ameliorate the oxidative stress of retinal cells. However, the current phototherapeutic devices are opaque, bulky, and tethered forms, so they are not feasible for use in continuous treatment during the patient's daily life. Herein, we report wireless, wearable phototherapeutic devices with red light-emitting diodes for continuous treatments. Red light-emitting diodes were formed to be conformal to three-dimensional surfaces of glasses and contact lenses. Furthermore, fabricated light-emitting diodes had either transparency or a miniaturized size so that the user's view is not obstructed. Also, these devices were operated wirelessly with control of the light intensity. In addition, in-vitro and in-vivo tests using human retinal epithelial cells and a live rabbit demonstrated the effectiveness and reliable operation as phototherapeutic devices
Outcome of cefazolin prophylaxis for total knee arthroplasty at an institution with high prevalence of methicillin-resistant Staphylococcus aureus infection
SummaryObjectivesThe aim of this study was to evaluate the outcome of cefazolin prophylaxis for total knee arthroplasty (TKA) in a hospital with a high prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infection.MethodsSince July 1, 2006, we have applied a ‘care bundle’ to TKA to prevent surgical site infection (SSI) without using vancomycin as antimicrobial prophylaxis, in accordance with the 1999 Hospital Infection Control Practices Advisory Committee guidelines. All patients undergoing TKA from July 1, 2006 to September 30, 2009 were enrolled. We reviewed data on SSI collected prospectively as part of routine infection control surveillance.ResultsOf 1323 TKAs, an SSI developed in 14 (1.06%) cases, which is comparable to the percentage obtained in other previous reports. When stratified by the National Nosocomial Infection Surveillance risk index, SSI rates were 0.86% (8/926), 1.30% (5/384), and 7.69% (1/13) in risk categories 0, 1, and 2, respectively. Of 14 SSIs, four (29%) were classified as superficial incisional, two (14%) as deep incisional, and eight (57%) as organ-space SSI.ConclusionsOur data suggest that antimicrobial prophylaxis using only cefazolin can maintain low SSI rates if other important infection management measures are employed, even where there is a high prevalence of MRSA infection
Outcomes of Split Liver Transplantation vs Living Donor Liver Transplantation in Pediatric Patients: A 5-Year Follow-Up Study in Korea
Background: The number of pediatric patients awaiting liver transplantation has decreased. Due to its increased use in Korea, split liver transplantation (SLT) may be a substitute for living donor liver transplantation (LDLT); however, the outcomes of pediatric SLT and LDLT in Korea remain unreported. Material/Methods: We reviewed data of Korean patients aged 18 years who received SLT from 2005 to 2014, based on the Korea national database and compared to recipients who underwent LDLTs at Seoul National University Hospital during the same period. Results: A total of 63 and 56 patients were included in SLT and LDLT, respectively. The most common indication for LT was biliary atresia (60.3% in SLT vs 67.9% in LDLT). The Pediatric End-Stage Liver Disease score did not differ between the groups (P 0.05). The 1-, 3-, and 5-year overall survival rates were 92.1%, 90.2%, and 86.6% in the SLT and 96.4%, 94.6%, and 94.6% in the LDLT groups, respectively (P=0.21); the corresponding graft survival rates were 88.9%, 87.1%, and 83.6% in the SLT and 92.9%, 91.0%, and 91.0% in the LDLT groups, respectively (P=0.31). Fulminant hepatic failure was a risk factor for graft failure [OR, 8.77 (1.08-70.92); P=0.042], but not Conclusions: The graft and overall survival rates of SLT and LDLT were not different in pediatric patients in Korea, and fulminant hepatic failure was the only risk factor affecting graft survival outcomes.N