Ali Al-Ghamdi

Using logistic regression to estimate the influence of accident factors on accident severity

Logistic regression was applied to accident-related data collected from traffic police records in order to examine the contribution of several variables to accident severity. A total of 560 subjects involved in serious accidents were sampled. Accident severity (the dependent variable) in this study is a dichotomous variable with two categories, fatal and non-fatal. Therefore, each of the subjects sampled was classified as being in either a fatal or non-fatal accident. Because of the binary nature of this dependent variable, a logistic regression approach was found suitable. Of nine independent variables obtained from police accident reports, two were found most significantly associated with accident severity, namely, location and cause of accident. A statistical interpretation is given of the model-developed estimates in terms of the odds ratio concept. The findings show that logistic regression as used in this research is a promising tool in providing meaningful interpretations that can be used for future safety improvements in Riyadh.

Analysis of traffic accidents at urban intersections in Riyadh

Previous studies have shown that intersection-related accidents account for about 50% of all accidents registered annually in Riyadh, the capital of the Kingdom of Saudi Arabia (KSA). More than half of these accidents are classified as severe. In this study, an attempt was made to investigate traffic accidents that occurred at both intersections and non-intersection sites. The goal was to analyze the nature of such accidents to determine their characteristics so that remedies could be sought or at least future research could be suggested. For this purpose, a sample of 1774 reported accidents was collected in a systematic random manner for the period 1996-1998 (651 severe accidents (accidents resulting in at least one personal injury or fatality) and 1123 property-damage-only (PDO) accidents). Conditional probability and contingency table analyses were used to make inferences from the data. The study found that improper driving behavior is the primary cause of accidents at signalized urban intersections in Riyadh; running a red light and failing to yield are the primary contributing causes. The analysis indicates that there is an urgent need to review existing intersection geometry along with the traffic control devices installed at these sites. In addition, public education campaigns and law enforcement strategies are urgently needed.

Emergency medical service rescue times in Riyadh

The emergency medical service (EMS) in Saudi Arabia is managed by each hospital through the Saudi Red Crescent Society (SRCS). There are approximately 165 ambulance stations in the country, each with two ambulances. The SRCS collects data on EMS requests and ambulance arrival times at the accident scene. Each emergency incident has its own implications (accident, fire, injury, etc.) and must be dealt with individually. The aims of this study are to evaluate ambulance rescue time, which includes response time, in the city of Riyadh, the capital of Saudi Arabia; to analyze this time for road traffic accidents; and to compare the response time in Riyadh with corresponding times in other countries. A sample of 874 emergency calls was collected during 1999. Ambulance rescue time consists of three components: response time, time at the scene and travel time to the hospital. Data analysis showed that rescue time is, on average, 35.84 min (S.D. = 6.43 min). Within this time, the average response time is 10.23 min (S.D. = 5.66 min). Other service components (e.g. ambulance time at the accident scene and travel time to the hospital) are analyzed and detailed statistics are given. Ambulance speed to the accident averages approximately 55.05 km/h (S.D. = 27.42 km/h). One primary finding is that there is room for improvement in the rescue time in Riyadh, which would save more lives, through an increase in the efficiency of ambulance team performance. A test statistic is developed in this study to carry out a simple hypothesis testing for percentiles. This test statistic, which is generic and can be used for other applications, is used to compare EMS response time in Riyadh with that in other parts of the world.

Entering Headway for Through Movements at Urban Signalized Intersections

When vehicles in a queue start crossing a stop line (or any other reference line) at a signalized intersection after the signal turns green, the entering headway (discharge headway) is the time that elapses between consecutive vehicles. This headway is a factor in determining intersection capacity. The current study aims at analyzing the entering headway at selected signalized intersections in Riyadh (the capital of Saudi Arabia). It is unlikely that driver behavior is similar in different countries, and therefore it is unwise to use the values for headway times from other countries to fit traffic conditions in Saudi Arabia. To date, no research of this type has been conducted in Saudi Arabia. This study attempts to investigate the entering headway at intersections in Riyadh and to compare the results with corresponding results from international research. Eight signalized intersections (with two-lane and three-lane approaches) along eight major streets in Riyadh were selected for study. A total of 720 single-lane traffic platoons entering the intersections were observed. It was found that the average entering headways for Vehicles 1 through 15 at two-lane intersections in Riyadh after the light turned green were 3.23, 2.41, 2.29, 2.1, 2.02, 1.84, 1.72, 1.64, 1.53, 1.68, 1.58, 1.31, 1.13, 1.19, and 1.01 s. For the three-lane sites the headways for Vehicles 1 through 13 were as follows: 3.37, 2.23, 2.03, 1.92, 1.81, 1.81, 1.72, 1.69, 1.6, 1.48, 1.37, 1.33, and 1.46 s. The study found that the saturation flow rates were 2,293 and 2,195 vehicles/hour of green per lane for two-lane and three-lane sites, respectively. These intersection approaches appear to have higher saturation flow rates than those in previous studies from other countries.

Diabetic retinopathy and its risk factors in a society with a type 2 diabetes epidemic: a Saudi National Diabetes Registry-based study

To assess diabetic retinopathy prevalence and its risk factors in a society with type 2 diabetes epidemic using the Saudi National Diabetes Registry (SNDR).

Analysis and Comparison of Trends in Extreme Temperature Indices in Riyadh City, Kingdom of Saudi Arabia, 1985–2010

This study employed the time series of thirteen extreme temperature indices over the period 1985–2010 to analyze and compare temporal trends at two weather stations in Riyadh city, Saudi Arabia. The trend analysis showed warming of the local air for the city. Significant increasing trends were found in annual average maximum and minimum temperatures, maximum of minimum temperature, warm nights, and warm days for an urban and a rural station. Significant decreasing trends were detected in the number of cool nights and cool days at both stations. Comparison of the trends suggests that, in general, the station closer to the city center warmed at a slower rate than the rural station. Significant differences were found in a lot of the extreme temperature indices, suggesting that urbanization and other factors may have had negative effects on the rate of warming at the urban station.

INJURY SEVERITY AND DURATION OF HOSPITAL STAY FOR URBAN ROAD ACCIDENTS IN RIYADH

A sample of 1,831 victims of urban road accidents in Riyadh was analyzed. The analysis consisted of two parts. First, the injury severity of 1,006 subjects was measured by the abbreviated injury scale (AIS). More than half the subjects were scaled with severe injuries (AIS ≥ 3). Association analysis between injury severity and accident characteristics (e.g., accident time, type, and location) was performed. Second, duration of stay at the hospital was examined for cases of injury as well as deaths. The probability density functions of the length of these time periods for cases of injury and death were found to be satisfactorily described by the γ distribution and by exponential distribution, respectively.

Cultural Pluralism in the Context of the Knowledge Society Ecosystem: Reviews and Views

With Huntington’s warning of a “clash of civilizations†following the end of the cold war, “cultural pluralism†has become important for enhancing world peace and supporting development. In this paper, cultural pluralism is viewed as a “knowledge society†problem, where intercultural knowledge is produced, disseminated and used within an ecosystem of mutual understanding and respect. The authors present key cultural pluralisms efforts, providing an overall picture of the issues involved. These efforts include: the 2001 United Nations (UN) resolution on dialogue among civilizations; the 2001 UN Educational, Scientific and Cultural Organization (UNESCO) declaration on cultural diversity; the 2005 Rabat conference on dialogue among cultures and civilizations; and the 2008 Madrid world conference on dialogue. In the second part of this paper, cultural pluralism issues are restructured according to the knowledge society ecosystem framework, where they are organized according to the five STOPE domains: strategy, technology, organization, people and the environment, and where they interact with the intercultural knowledge activities. The resulting cultural pluralism ecosystem framework is useful as a tool for organizing and interrelating future studies on the subject and promoting peace and development.

Sympathetic ophthalmia after successful retinal reattachment surgery with vitrectomy

Purpose To report a case of sympathetic ophthalmia (SO) following one successful pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment. Methods Case report. Results A 50-year-old man developed SO 5 weeks after successful repair of rhegmatogenous retinal detachment with PPV and intraocular gas tamponade. The patient presented with bilateral multifocal exudative retinal detachments and inflamed optic nerve with characteristic changes of SO detected by fluorescein angiography, indocyanine green angiography, and optical coherence tomography. Prompt use of systemic steroids and cyclosporin A resulted in control of the uveitis with significant visual improvement. Conclusions PPV should be viewed as a major risk factor for development of SO.

A Framework for the Knowledge Society Ecosystem: A Tool for Development

With the increasing worldwide need for the development of the knowledge society, multi-disciplinary research concerned with the subject is becoming of increasing importance. This paper introduces a framework that provides a comprehensive scope of the knowledge society ecosystem that organizes and integrates its various issues. The framework gives a tool for identifying, structuring, and inter-relating, knowledge society problems that need to be investigated. At the core of the framework is the “knowledge circle”, with its activities of knowledge generation, diffusion, and utilization that can lead to sustainable development. The framework considers the basic domains, interacting with these activities, to be based on the STOPE view of “strategy, technology, organization, people, and the environment”. The paper addresses the use of the framework as a generic common base for future investigations on the development of the knowledge society.