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STUDY OBJECTIVES: This study aimed to identify prospectively the correlation between obstructive sleep apnea (OSA) severity, ocular microcirculation changes, and visual function changes in patients with glaucoma. METHODS: We prospectively enrolled patients with glaucoma who were willing to undergo overnight polysomnography. The enrolled patients were further divided into normal tension glaucoma, high-tension glaucoma, and control. Visual field progression was analyzed using sequential standard automated perimetry. Peripapillary and macular vessel density were assessed through optical coherence tomography angiography (OCT-angiography). The associations between polysomnography parameters, OCT-angiography parameters, and visual field progression were analyzed. RESULTS: A total of 22 patients with normal tension glaucoma, 30 patients with high-tension glaucoma, and 24 control patients were enrolled. Through regression analysis, glaucoma was found to be an independent predictor of moderate-to-severe OSA (P = .035); furthermore, moderate-to-severe OSA was significantly associated with visual field progression (P = .008 in the high-tension glaucoma subgroup and P = .008 in the overall glaucoma). Additionally, OSA severity was negatively correlated with the ganglion cell complex thinning rate in the normal tension glaucoma subgroup. CONCLUSIONS: Presence of glaucoma increased the risk of moderate-to-severe OSA compared with the control group. OSA severity was related to visual field deterioration in patients with glaucoma and further associated with structural progression in the normal tension glaucoma subgroup. Careful monitoring of the comorbid OSA status of patients with glaucoma is essential to prevent disease progression. CITATION: Chan Y-H, Chuang L-H, Yu C-C, et al. Prospective evaluation of the comorbidity of obstructive sleep apnea in patients with glaucoma. J Clin Sleep Med. 2022;18(1):47–56.

This retrospective cross-sectional study, which enrolled 124 normal tension glaucoma (NTG) eyes and 68 healthy eyes as the control, determined the association between central corneal thickness (CCT) and ocular parameters in NTG. CCT was measured using the Pentacam® system, optical coherence tomography angiography (OCT-A) was adopted to measure the peripapillary and macular area VDs, and spatial data were based on the Garway–Heath map as illustrated in OCT-A. Univariate and multivariate linear regressions were used to statistically analyze for associations between CCT and other factors. In this study, the mean age was similar for both the NTG and control groups. The mean CCT of the NTG group was significantly thinner than that of the control group (533.97 ± 33.11 µm vs. 546.78 ± 38.21 µm; p = .022). Considering all the factors, CCT negatively correlated with visual field (VF) pattern standard deviation (univariate, p = .045). To analyze structural and functional factors separately, we found a significant positive correlation between CCT and whole disc radial peripapillary capillary VD (VDRPC; multivariate, p = .019). To analyze the relationship between all factors and sectoral changes in VDRPC, a significant positive correlation was observed between CCT and inferior temporal VDRPC (univariate, p = .039) and inferior nasal VDRPC (VDRPC IN; univariate, p = .048). In conclusion, this novel study shows that among NTG participants, a thinner cornea correlated with weaker biomechanical properties susceptible to optic nerve tissue displacement, especially in response to mild transient elevation of IOP, leads to compromised ocular microcirculation.

This study characterized and evaluated normal tension glaucoma (NTG) in obstructive sleep apnea syndrome (OSAS).In this retrospective, cross-sectional study, all participants were examined with polysomnography (PSG). Functional parameters of standard automated perimetry (SAP) were recorded. Structural parameters in optical coherence tomography angiography (OCTA) included peripapillary superficial vessel density (VD RPC), peripapillary whole-layer (VD NH), and superficial and deep macular area VD. Participants were categorized into perimetric and nonperimetric groups by SAP result. Low reliability of SAP and signal strength index

This article presents a computational model for the optimum design of an urban inter-modal public transit network. A software tool based on this model was developed to provide useful reference for transport planners in carrying out service planning, routing, and scheduling for an inter-modal transit network. The development of this model is briefly described here. A numerical example is used to illustrate its implementation. Results of sensitivity analyses demonstrate that it is capable of providing reasonable solutions and is responsive to changes in the planning environment.

Many studies have focused mainly on the development of a single automatic incident detection algorithm to detect incident occurrences, and the performance obtained has often been mixed. In this study, an algorithm fusion method was developed using incident data collected from the Central Expressway in Singapore. This method explores the possibility of enhancing incident detection performance by combining the complementary advantages of a group of existing algorithms. It was found that the fused algorithm with the following options has outperformed the existing algorithms: Fusion Option II—selecting a combination of the best-performing algorithms, and Fusion Option III—applying different weightings to a group of algorithms. Compared with the existing dual variable/combined detector evaluation algorithms developed earlier for the same studied site, the fused algorithms performed significantly better, with false alarm rates between 0.2 and 1.0%. At a detection rate of 90%, these fused algorithms were able to...

In heavy traffic flow conditions, vehicles have limited manouverability which affects the magnitude of response to incident-induced traffic disturbances and how fast changes in these traffic variables can signal the occurrence of an incident. Such characteristics are usually used to formulate a loop-based algorithm. A recent study reported that some existing algorithms were not able to maintain a desired level of effectiveness when these algorithms were used to detect incidents with a video-based detector system. Two new video-based automatic incident detection algorithms, the INdividual Detection Evaluation (INDE) and COmbined Detection Evaluation (CODE) algorithms were, therefore, developed for the detection of lane-blocking incidents in heavy traffic flow conditions using the Central Expressway in Singapore as a case study. The algorithms detect incident-induced traffic speed and occupancy disturbances differently: INDE processes information at each individual detector station and CODE processes inform...

Globalisation has generated more shipping traffic and congestion at some seaports. The sea space capacity of a port is important to planning and operation. To assist in port planning, we present a decision support system. It has an interactive interface to facilitate entry and editing of data which include information for developing a sea space network, operational procedures, traffic pattern, etc. The system estimates the capacities of various port facilities and the entire sea space. By loading a traffic pattern onto the network, bottlenecks within the port waters can be identified. One can use it to assess the effectiveness of congestion management measures, and to study the impacts of planning concepts, operational procedures, etc. The logic and structure of the system are generic and can be applied to any sea space.

PURPOSE We evaluated the clinical results of nonsimultaneous penetrating keratoplasty, cataract extraction, and intraocular lens (IOL) implantation (two-stage surgery) for combined corneal disease and cataract. METHODS Twenty-six eyes of 24 patients with an average age of 46 years who underwent two-stage surgery were studied retrospectively. Variables included visual acuity, refractive status, specular microscopy before and after IOL implantation (6 months), and the occurrence of graft failure. Astigmatism was corrected by suture removal and relaxing incision. The mean follow-up after IOL placement was 16 months. RESULTS Unaided visual acuity was 20/100 or better in 22 (83%) eyes after the second procedure. Twenty-one (81%) eyes had an aided visual acuity of at least 20/40. The mean refractive and absolute errors were -1.49 +/- 1.39 diopters (D) and 1.55 +/- 1.30 D, respectively. The mean keratometric and refractive cylinders were 3.50 D and 2.26 D, respectively. Nineteen (73%) eyes had a spherical equivalent refraction within 2 D of emmetropia. Anisometropia (> or =3 D) occurred in four (15%) eyes. The endothelial cell density, the coefficient of variation, and the percentage of hexagonal cells documented by specular microscopy were not significantly different before and after IOL implantation. Complications included three rejections, two cases of herpetic recurrence, and one late decompensation. Two graft failures (8%) occurred after secondary surgery. CONCLUSION The two-stage surgery is a safe and effective modality.

Sea space planning and congestion management is receiving more attention. However, little work on sea space capacity and strategy analyses can be found in the literature. Compared to other transportation systems, a sea space system has some special features that require consideration. The system capacity also depends on the pattern of traffic using the system. In this paper, we model a sea space as a directional network and capacity models for berthing areas, anchorage areas, fairways and their intersections, as well as the entire sea space system are developed. These models can be used to compute capacity for any given traffic pattern which can be extracted from vessel trip records or from traffic forecasts. To implement these models, a software system called Sea Space Capacity and Strategy Analysis System (SCSAS) has been developed in Visual C + + and is now being used in Singapore.

Traffic volume and travel time data collected at a number of arterial roads in Singapore were used to analyze the speed-flow relationships for radial and ring arterial roads. A new travel time–density model was formulated by incorporating “minimum delay per intersection” and “frequency of intersections per kilometer” as model parameters. The appropriate values of these model parameters also were established. The adjusted R2 value of this model was higher than those for the journey speed–density and running speed–density relationships. The free-flow speed and maximum flow values of the travel time–density model also fitted favorably well with field data compared with those of the journey-speed models. The radial road capacity estimates range from 835 passenger cars per hour per lane (pc/h/l) for segments with uncoordinated (unlinked) traffic signals to 905 pc/h/l for segments with proper signal (linked) coordination. Not much difference in estimated capacities is observed between linked and unlinked segmen...

Estimation of parking generation of a proposed development is important in facility planning and traffic impact assessment. Studies of parking generation of various land uses have been conducted by many researchers in western countries but few for Asian conditions. In many cases, parking requirements of proposed developments in Asian cities are determined using rates developed for western cities. This may not be appropriate because there are differences in levels of vehicle ownership, public transport service, and traffic management as well as land-use planning. Such differences can result in poorly planned facilities. This paper reports the development of parking generation rates of commercial developments in Singapore. The study found that parking rates depend on the available floor area of the site and whether the site is well served by public transport. The estimated rates for Singapore are about one-quarter to one-third of those reported for similar developments in western cities. An evaluation of two methods of estimating parking generation rates indicated that the regression method provides better estimates.

The monosodium salt of Carbon-14 labeled paclitaxel (Taxol®) [N3′-14COPh] 2′-ethyl carbonate 7-phosphonooxymethyl ether, was prepared from C-14 labeled paclitaxel [N3′-14COPh] in 5 steps. The radiochemical purity of the final product was greater than 99% and the specific activity was 25 μCi/mg. © 1997 John Wiley & Sons, Ltd.

The synthesis, pharmacokinetic properties, and antitumor evaluation of novel paclitaxel phosphonooxymethyl ether derivatives 8–11 and salts thereof is described. These compounds exhibit improved water solubility as compared to paclitaxel (1) and upon incubation with plasma and alkaline phosphatase they readily release parent drug. The in vivo antitumor evaluation of compounds 8–11 established them as suitable pro-drugs of paclitaxel.

An area-wide traffic speed-flow model was developed for the Singapore CBD with the aim of providing an analytical framework for the evaluation of traffic management measures for the area (known as the Restricted Zone). A major survey of traffic speed and volume within the CBD was conducted in 1990. The speed data were collected using a fleet of floating cars which moved around two fixed survey circuits for 3 days. In the modelling process that followed, several approaches and mathematical models were studied. The final, recommended model relates journey speeds inside the Zone with the average traffic flow per lane inside the area which, in turn, is correlated with the cordon traffic volume. Thus, the model allows one to estimate average journey speed inside the Zone, based on the total traffic flow crossing the Zone cordon.

An HPLC method for the determination of diclofenac (DCF) and four of its metabolites (3'-hydroxydiclofenac, 4'-hydroxydiclofenac, 5-hydroxydiclofenac, and 3'-hydroxy-4'-methoxydiclofenac) in human urine is described. Following base hydrolysis, the samples were neutralized and extracted. Evaporated extracts were reconstituted in mobile phase containing ascorbic acid, and chromatographed, using flow-rate programming, on a reversed-phase column. Absolute recovery (average), was at least 78% for diclofenac and ranged from 75 to 85% for the four metabolites. Standard curves showed linearity over the range of concentrations of 0.2 to 40 ug/mL, using 0.25 mL of urine. Specificity was demonstrated by examining chromatograms of extracts of blank urine from 8 volunteers and 24 study subjects. Good accuracy was observed for all compounds over the concentration range of 0.2 to 40 ug/mL using 0.25 mL of urine. Based on accuracy and precision criteria, the limit of quantitation for all 5 analytes was 0.4 ug/mL, using 0.25 mL of urine. Analysis of urine from subjects with normal and reduced renal function who received diclofenac orally demonstrated that total diclofenac and metabolites excreted in the urine represented approximately 31% and 4% of an oral dose of diclofenac, respectively.

The estimation of runway capacity is important in airport planning and operational analysis. Standard procedures for capacity determination typically assume that there is no constraint on aircraft operations and do not provide good estimates when constraints exist. This paper presents a study of runway capacity at Singapore Changi Airport in which local operational constraints are taken into account. In addition, the impacts on capacity due to marine vessel crossings in a shipping channel near the airport, and the timing for implementation of simultaneous, independent instrument approach procedures are also investigated. The levels of annual aviation demand that could be served without excessive delays to aircraft under various operating scenarios are estimated.

The ground access system at Singapore Changi Airport is analyzed. The emphasis is on understanding traffic characteristics and utilization of access facilities. The applicability of typical ground access planning parameters recommended for western airports to Changi Airport is also investigated. Peak traffic levels are found to be manageable. The curbside is the critical link of the access system but congestion in peak periods do not last very long at present. Although the two public car parks together provide enough parking spaces, the closer-in car park is always full in the evening, while the cheaper car park is usually half empty even though it is only 250 m farther. This suggests convenience is more important than cost to most users.

Energy costs and availability are major concerns in most parts of the world. Various measures to reduce energy consumption have been proposed. This paper focuses on two strategies to control aircraft ground operations as fuel conservation measures: operating fewer engines while taxiing, and towing aircraft between terminal area and runways. The potential benefits, costs, safety and operational issues related to implementation are investigated. As an illustration, the implementation of these strategies at ten major US airports is analyzed. About 278 million liters of jet fuel could potentially be saved from aircraft towing at these airports at their 1987 operation levels. However, there are some concerns related to towing which would make implementation unlikely until there is more urgency in fuel conservation. A more readily implementable strategy would be operating fewer engines while taxiing. About 88 million liters of fuel could potentially be conserved at these airports at 1987 operation levels.

BACKGROUND AND OBJECTIVE: To assess the long-term results of Nd:YAG laser iridotomy in the treatment of patients with primary angle-closure glaucoma and occludable angles to evaluate the risk–benefit ratio and the role of gonioscopy in predicting the outcome after Nd:YAG laser iridotomy. PATIENTS AND METHODS: The records of 138 consecutive patients (231 eyes) who underwent Nd:YAG laser iridotomy in one hospital during 3 years (from 1989 to 1991) were reviewed. The mean follow-up period was 51 months. RESULTS: Of all eyes, 25.1% were treated for chronic angle-closure glaucoma and 10.8% were treated for acute angle-closure glaucoma; most eyes (64.1%) underwent prophylactic iridotomy for occludable angles. Decreased intraocular pressure (IOP) was noted in most eyes after Nd:YAG laser iridotomy; only 10 eyes required further filtration surgery. Visual acuity was unchanged or improved in 97.9% of all eyes at the 6-month visit. Cataract progression was primarily responsible for those eyes with decreased acuity. Ninety-seven percent of eyes had quantitatively wider angles after laser treatment; 8 of 14 eyes with peripheral anterior synechiae of more than 270° underwent further surgery to control IOP. Transient elevated IOP and iris bleeding occurred in 23.5% and 12.2% of the eyes, respectively; other complications were rare. CONCLUSION: Nd:YAG laser iridotomy is a safe and effective procedure for the treatment and prevention of angle-closure glaucoma. Gonioscopy is useful to predict the outcome after Nd:YAG laser iridotomy. [Ophthalmic Surg Lasers Imaging 2003;34:291–298.]

The microwave landing system (MLS) is scheduled to replace the existing instrument landing system as precision guidance for instrument operation by the turn of this century. This paper focuses on the impact of MLS on runway capacity. The advantage of MLS in this regard falls mainly on the more precise guidance and broader coverage possible. Capacity gains achievable for single‐runway, dual‐lane, and intersecting‐runway configurations using the multiple horizontal approach paths and variable glide slope capabilities of MLS are analyzed. The analysis considered mixed operations (i.e., both arrivals and departures) for a wide variety of aircraft mixes. With multiple horizontal approach paths, an increase of 5–8% in capacity can be expected for all runway configurations. With the use of different glide paths, capacity gains range from 4–12% for single and two‐intersecting runway configurations, to 10–35% for dual‐lane configurations, depending on minimum vertical separation requirement and angle of descent.

The movement of aircraft in the terminal airspace is simulated using a fast‐time, critical events model. The model tracks the flight of each aircraft within the airspace studied and estimates aircraft delays within the terminal airspace. It also provides other relevant statistics such as controller workload, flow rates and travel times. The airspace model is capable of simulating a multi‐airport, multi‐sector environment. It incorporates logic that minics controller coordination and anticipation, and includes consideration of conflict resolution, aircraft speed control, overtake situation, aircraft holding and dynamic runway assignment. Operational data collected in the field were used in a model evaluation exercise. Results indicated that the model is capable of simulating real‐world aircraft operations in the terminal airspace.

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