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Research Interests: Obesity, Diet, Saudi Arabia, Health, Public Health, and 26 moreAdolescent, Early Childhood, Fast Food, Overweight, Humans, Child, Developing Country, Public, Chronic Disease, Female, Male, Young Adult, Exercise, Food Frequency Questionnaire, Body Mass Index, Waist Circumference, Fruit and vegetables, School Children, Questionnaires, Body mass index (BMI), Food habits, Public health systems and services research, Dietary pattern, Multivariate Regression, Carbonated Beverages, and Dietary Habits
Research Interests: Genetics, Statistics, Monte Carlo Simulation, Saudi Arabia, Risk assessment, and 20 moreCongenital Heart Defects, Humans, Female, Male, Confidence intervals, Siblings, Incidence, Risk factors, Sample Size, Registries, Consanguinity, Risk Factors, Risk Assessment, Congenital Heart Disease, Reference Values, Family Study, Likelihood Functions, Monte Carlo Method, Confidence Interval, and Case Control Studies
There is marked regional variation in organ donation among the different regions of Saudi Arabia. Our aim was to study the dominating factors for these variations to improve organ donation in low-donation areas. This study was a... more
There is marked regional variation in organ donation among the different regions of Saudi Arabia. Our aim was to study the dominating factors for these variations to improve organ donation in low-donation areas. This study was a retrospective review of the Saudi Center for Organ Transplantation data for cadaveric organ donation from 2006 to 2012, with the number of cases reported, documented, consented, and harvested in various regions (northern, southern, eastern, western, and central). The region, number, and size of contributing intensive care units (ICUs), overall donation rate, and transplanted rate (potential donor and those harvested, respectively) were also reviewed. Between 2006 and 2012, a total of 512 cases were procured and analyzed from Saudi Arabia. From the central region, 393 were acquired, representing 76.7% of the total consented cases. These 393 cases came from 30 of 97 contributing ICUs (31%). The eastern region was ranked second, followed by the western region. ...
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Bubble behavior and mean bubble diameter in subcooled upward flow boiling in a vertical annular channel were investigated under low pressure and mass flux conditions. High-speed photographic results indicated that, contrary to the common... more
Bubble behavior and mean bubble diameter in subcooled upward flow boiling in a vertical annular channel were investigated under low pressure and mass flux conditions. High-speed photographic results indicated that, contrary to the common understanding, bubbles tend to detach from the heating surface upstream of the net vapor generation point. Digital image processing technique was used to measure the mean
Research Interests: Mechanical Engineering, Chemical Engineering, Image Processing, Photography, Two Phase Flow, and 15 moreHeat Transfer, Digital Image Processing, Porosity, Images, Flow Visualization, Heat Flux, Fluid flow, High Speed, Size, Heating, Interdisciplinary Engineering, Boiling, Low Pressure Boiler, Vapors, and Void Fraction
The objective of this study was to illustrate methods for investigating factors associated with seasonality, using milk-component production as an example. Milk-protein and fat percentages showed a seasonal pattern; percentages were... more
The objective of this study was to illustrate methods for investigating factors associated with seasonality, using milk-component production as an example. Milk-protein and fat percentages showed a seasonal pattern; percentages were lowest during June and July and highest in October and November. Graphical methods were used to compare herd calving patterns to seasonal production patterns and spectral analysis were used to compare seasonal production patterns between farm groups with different management practices. For the comparison of seasonality of production and herd calving patterns, data was obtained from archival records for all cows enrolled in Dairy Herd Improvement (DHI) milk recording in Ontario, Canada from 1990 to 1994. For comparisons of seasonality and management practices, monthly protein and fat percentages were obtained from the Dairy Farmers of Ontario from March 1985 to July 1994. Management information was obtained from responses to questionnaires completed by 364 dairy producers in Ontario. Graphical analyses provided a visualization of the relationship between herd calving patterns and seasonality of production – however, graphical methods alone did not allow statistical inferences to be made. Spectral analyses provided a formal statistical test of the null hypothesis of no association between an independent variable (farm management type) and seasonal production pattern in the data over time, provided that the outcome followed the same seasonal pattern regardless of covariate levels under the null hypothesis.
Research Interests: Reproduction, Animal Husbandry, Preventive Veterinary Medicine, Lipids, Seasonality, and 16 moreStatistical Inference, Animals, Ontario, Risk factors, Seasonal variation, Milk, Cattle, Questionnaires, Spectrum analysis, Risk Factors, Veterinary Sciences, Seasons, Farm management, Statistical Test, Dairying, and Milk proteins
Impeccable assessment of symptoms is central to palliative care (PC) practice. The study objectives are (1) to test the validity of the Arabic Questionnaire for Symptom Assessment (AQSA) as a self-administered (SA) tool for assessing the... more
Impeccable assessment of symptoms is central to palliative care (PC) practice. The study objectives are (1) to test the validity of the Arabic Questionnaire for Symptom Assessment (AQSA) as a self-administered (SA) tool for assessing the severity of the listed symptoms among PC patients and (2) to test the validity of AQSA when completed by a proxy. The AQSA is a tool for assessing the severity of 11 symptoms in addition to the overall suffering experience on a 0 to 10 numeric scale. Symptom scores on the SA AQSA were compared to scores obtained through interviews with patients. The same procedure was repeated with patients' sitters to explore the validity of using the tool for symptom assessment by proxy. The study involved 107 pairs (a patient and a sitter, each) with a mean age of 46.3 years (females 59.8%) for patients and 35.9 years (females 65.7%) for sitters. The correlation coefficient (r) for agreement between SA and interview-based (IB) scores for patients ranged from ...
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This symposium was sponsored by the Multiphase Flow Committee of the ASME Fluids Engineering Division. The objective of the symposium was to bring together researchers, and practicing engineers in the area of gas-liquid flows, to share... more
This symposium was sponsored by the Multiphase Flow Committee of the ASME Fluids Engineering Division. The objective of the symposium was to bring together researchers, and practicing engineers in the area of gas-liquid flows, to share their knowledge and discuss the state of the art. Gas-liquid flows appear in a multitude of settings, some natural and some designed to achieve desired functions. Examples of the latter type of two-phase flows are: spray, drying, atomization, boiling which occurs in scrubbers, fountains, boilers, etc. However, two-phase flow can also appear in systems which are in accident conditions such as inadvertent depressurization or heat up in nuclear reactors. The gas-liquid flows offer a challenge to our understanding, due to the complex and stochastic nature of the interface. the flow regime determination is crucial for estimating the interfacial transfer processes. The modeling of two-phase flow requires many empirical correlations such as interfacial area density or coefficients of transfer processes at the interface or at the wall. The scaling of two-phase flow provides another challenge as there are many length and time scales in every flow regime. Papers cover modeling, theory and experiments. The papers are arranged in six sessions. The first two sessions deal with the experiments and the remaining four describe the analytical effort. All papers were processed separately for inclusion on the data base.
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An approximate x2-test statistic tests the homogeneity of scale parameters of several exponential distributions from a Bayes viewpoint under types I and II censoring. The quantiles of the statistic are simulated and found to be very close... more
An approximate x2-test statistic tests the homogeneity of scale parameters of several exponential distributions from a Bayes viewpoint under types I and II censoring. The quantiles of the statistic are simulated and found to be very close to the exact quantiles of a x2 distribution.
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ABSTRACT The problem of estimating the intraclass correlation when the sampling design is unbalanced is discussed. The method of moments is used to derive an approximation to the distribution of the estimate of the intraclass correlation... more
ABSTRACT The problem of estimating the intraclass correlation when the sampling design is unbalanced is discussed. The method of moments is used to derive an approximation to the distribution of the estimate of the intraclass correlation obtained by the variance components approach. The maximum likelihood estimator is also presented, along with a simple procedure due to Richard (1961), for numerically maximizing a likelihood function of several parameters. Finally, the issue of optimal study design is considered for both balanced and unbalanced situations. For given power we determine the number of sets required to detect different values of the intraclass correlation.
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Vaginal penetration phobia is a common and distressing problem world.wide. It interferes with vaginal penetrative sexual relations, and leads to unconsummated marriage (UCM). This problem may be heightened in Arab women, due to cultural... more
Vaginal penetration phobia is a common and distressing problem world.wide. It interferes with vaginal penetrative sexual relations, and leads to unconsummated marriage (UCM). This problem may be heightened in Arab women, due to cultural taboos about pain and bleeding, that may be associated with the first coital experience after marriage. Data about this problem is scarce in Arab societies. The aim of this study was to evaluate the response of these women and their husbands to an individualized, psychotherapeutic assessment and treatment to resolve this problem. Retrospective descriptive in a general gynecology community setting over a 6-year period. The study involved a retrospective sequential cohort of 100 Arab couples with UCM due to the woman's VPP. They were evaluated by a female gynecologist in out patient clinics. Data was collected through chart review, and telephone interviews. Final analysis was performed on 100 Arab couples, who satisfied the inclusion criteria. They...
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The Petrifilm HEC test (3M Canada Inc., London, Ontario), a quantitative microbiological test for Escherichia coli O157:H7, was evaluated for its performance as a beef-carcass monitoring test. Test repeatability and agreement and... more
The Petrifilm HEC test (3M Canada Inc., London, Ontario), a quantitative microbiological test for Escherichia coli O157:H7, was evaluated for its performance as a beef-carcass monitoring test. Test repeatability and agreement and agreement with an E. coli O157:H7 detection method using a hydrophobic grid membrane filter (HGMF) overlaid onto cefixime-tellurite-sorbitol MacConkey agar (CT-SMAC) followed by a latex agglutination test for the O157 antigen were determined by using pure cultures of E. coli O157:H7, beef samples experimentally contaminated with bovine feces containing E. coli O157:H7, and naturally contaminated beef carcasses of unknown E. coli O157:H7 status from a local abattoir. The Petrifilm HEC test showed excellent repeatability and excellent agreement with the HGMF-CT-SMAC method when test samples were obtained from pure cultures and experimentally contaminated meat. All 125 naturally contaminated beef carcasses surveyed were negative for E. coli O157:H7 with both microbial methods. The Petrifilm HEC test, however, demonstrated a significantly lower proportion of cross-reactive organisms (false-positive reactions) than the HGMF-CT-SMAC method. Given the performance of this test coupled with its ease of use and compact size, it shows considerable promise for carcass testing where abattoir laboratory facilities are limited and as a substitute for more complex laboratory testing methods used in established laboratories.
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The purpose of this study was to assess agreement between a wet reagent and a dry reagent analyzer. Thirteen analytes (albumin, globulin, alkaline phosphatase, alanine aminotransferase, amylase, urea nitrogen, calcium, cholesterol,... more
The purpose of this study was to assess agreement between a wet reagent and a dry reagent analyzer. Thirteen analytes (albumin, globulin, alkaline phosphatase, alanine aminotransferase, amylase, urea nitrogen, calcium, cholesterol, creatinine, glucose, potassium, total bilirubin, and total protein) for both canine and feline serum were evaluated. Concordance correlations, linear regression, and plots of difference against mean were used to analyze the data. Concordance correlations were excellent for 8 of 13 analytes (r > or = 0.90); the correlations for albumin, potassium, and calcium were clinically unreliable. The linear regression analysis revealed that several analytes had slopes significantly different from unity, which was likely related to methodological differences. Compared to the wet reagent analyzer, the dry reagent analyzer showed excellent agreement for alkaline phosphatase, alanine aminotransferase, amylase (feline), urea nitrogen, cholesterol, creatinine, glucose, total bilirubin (canine), and total protein. However, it showed only slight to substantial agreement for amylase (canine), calcium, albumin, potassium, and total bilirubin (feline).
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To describe the Registry and report preliminary data for the prevalence of 5 prothrombotic gene mutations in the normal Saudi population. Blood from consenting healthy Saudi individuals and patients with venous thrombosis (VT) from... more
To describe the Registry and report preliminary data for the prevalence of 5 prothrombotic gene mutations in the normal Saudi population. Blood from consenting healthy Saudi individuals and patients with venous thrombosis (VT) from different regions of the Kingdom was collected from November 2001 until July 2007. The extracted DNA of each sample was kept at -70 degrees C until tested for 5 known prothrombotic factors using established methods. Only patients with confirmed VT were included. Data generated through direct interview were entered into the Saudi Thrombosis and Familial Thrombophilia (S-TAFT) Register. The consent and demographic data collection forms and the S-TAFT Register were developed using the SQL web based software. Nine hundred and two DNA samples of consenting healthy Saudi individuals were tested for factor V Leiden (FVL), prothrombin (PT) 20210 G>A, 5-10 methylenetetrahydrofolate reductase (MTHFR) 677 C>T, the 4G/5G polymorphism of Plasminogen activator in...
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ABSTRACT Although the role of folic acid (FA) in preventing neural tube defects (NTDs) is well documented, its optimal intake in pregnant women is still low in many countries. Here, we prospectively studied the prevalence of NTDs in the... more
ABSTRACT Although the role of folic acid (FA) in preventing neural tube defects (NTDs) is well documented, its optimal intake in pregnant women is still low in many countries. Here, we prospectively studied the prevalence of NTDs in the newborns and the patterns of FA intake in pregnant Saudi mothers.
Although hepatitis C virus (HCV) genotype 4 has been reported to be prevalent in some countries of the Middle East, the genotype distribution in some geographical areas is not conclusive. We aimed to perform a meta-analysis on available... more
Although hepatitis C virus (HCV) genotype 4 has been reported to be prevalent in some countries of the Middle East, the genotype distribution in some geographical areas is not conclusive. We aimed to perform a meta-analysis on available literature on this issue in an attempt to identify or confirm the prevailing HCV genotypes in Saudi Arabia. We searched for reports describing genotypes in Saudi Arabia. A meta-analysis was performed on the samples in 18 studies, published between 1995 and 2011, in which HCV genotypes were identified. A total of 2277 specimens from 18 studies showed that 617, 82, 119 and 1198 subjects were HCV-positive for genotypes 1, 2, 3 and 4, respectively. The meta-analyses showed that there is a great deal of heterogeneity in estimated prevalence among the studies. The highest prevalence was found in genotype HCV-4, followed by HCV-1, HCV-3, and HCV-2. Our meta-analysei emphasizes that HCV genotype 4 is the most prevalent, followed by genotype 1. Further studie...
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To describe the Registry and report preliminary data for the prevalence of 5 prothrombotic gene mutations in the normal Saudi population. Blood from consenting healthy Saudi individuals and patients with venous thrombosis (VT) from... more
To describe the Registry and report preliminary data for the prevalence of 5 prothrombotic gene mutations in the normal Saudi population. Blood from consenting healthy Saudi individuals and patients with venous thrombosis (VT) from different regions of the Kingdom was collected from November 2001 until July 2007. The extracted DNA of each sample was kept at -70 degrees C until tested for 5 known prothrombotic factors using established methods. Only patients with confirmed VT were included. Data generated through direct interview were entered into the Saudi Thrombosis and Familial Thrombophilia (S-TAFT) Register. The consent and demographic data collection forms and the S-TAFT Register were developed using the SQL web based software. Nine hundred and two DNA samples of consenting healthy Saudi individuals were tested for factor V Leiden (FVL), prothrombin (PT) 20210 G>A, 5-10 methylenetetrahydrofolate reductase (MTHFR) 677 C>T, the 4G/5G polymorphism of Plasminogen activator in...
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In this paper we propose the use of the within-subject coefficient of variation as an index of a measurement's reliability. For continuous variables and based on its maximum likelihood estimation we derive a variance-stabilizing... more
In this paper we propose the use of the within-subject coefficient of variation as an index of a measurement's reliability. For continuous variables and based on its maximum likelihood estimation we derive a variance-stabilizing transformation and discuss confidence interval construction within the framework of a one-way random effects model. We investigate sample size requirements for the within-subject coefficient of variation for continuous and binary variables. We investigate the validity of the approximate normal confidence interval by Monte Carlo simulations. In designing a reliability study, a crucial issue is the balance between the number of subjects to be recruited and the number of repeated measurements per subject. We discuss efficiency of estimation and cost considerations for the optimal allocation of the sample resources. The approach is illustrated by an example on Magnetic Resonance Imaging (MRI). We also discuss the issue of sample size estimation for dichotomo...
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Data recorded in a herd health management system were obtained from 32 registered Holstein dairy herds from British Columbia. Frequencies of disease were described, and the effect of herd, age, year, season, and the interrelationships... more
Data recorded in a herd health management system were obtained from 32 registered Holstein dairy herds from British Columbia. Frequencies of disease were described, and the effect of herd, age, year, season, and the interrelationships between diseases within a lactation on the occurrence of disease were evaluated. Lactational incidence rates were computed for diseases with a short period of risk (ie, udder edema, milk fever, retained placenta, metritis, displaced abomasum, and ketosis), whereas for diseases with a longer period of risk (ie, cystic ovaries, mastitis and stable footrot), incidence densities were calculated. Overall, the disease incidence was low and showed an increase in frequency by year, which we attributed to more observing and complete recording by the owner, rather than an actual increase in disease incidence. Most diseases occurred early in lactation and their frequency increased with lactation number; the exception was udder edema, which occurred mainly during ...
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The purpose of this study was to assess agreement between a wet reagent and a dry reagent analyzer. Thirteen analytes (albumin, globulin, alkaline phosphatase, alanine aminotransferase, amylase, urea nitrogen, calcium, cholesterol,... more
The purpose of this study was to assess agreement between a wet reagent and a dry reagent analyzer. Thirteen analytes (albumin, globulin, alkaline phosphatase, alanine aminotransferase, amylase, urea nitrogen, calcium, cholesterol, creatinine, glucose, potassium, total bilirubin, and total protein) for both canine and feline serum were evaluated. Concordance correlations, linear regression, and plots of difference against mean were used to analyze the data. Concordance correlations were excellent for 8 of 13 analytes (r > or = 0.90); the correlations for albumin, potassium, and calcium were clinically unreliable. The linear regression analysis revealed that several analytes had slopes significantly different from unity, which was likely related to methodological differences. Compared to the wet reagent analyzer, the dry reagent analyzer showed excellent agreement for alkaline phosphatase, alanine aminotransferase, amylase (feline), urea nitrogen, cholesterol, creatinine, glucose,...
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The objective of this study was to analyze the survivorship of dairy cows after displaced abomasum was diagnosed. Survivorship from the calving preceeding diagnosis of displaced abomasum to removal from the herd was investigated for cows... more
The objective of this study was to analyze the survivorship of dairy cows after displaced abomasum was diagnosed. Survivorship from the calving preceeding diagnosis of displaced abomasum to removal from the herd was investigated for cows that were diagnosed with displaced abomasum compared with herdmates. For cows that were diagnosed with displaced abomasum, factors that affected survivorship from the diagnosis of the disease to removal were investigated. Data from a total of 135 cows that had been diagnosed with displaced abomasum and 373 controls matched by herd and lactation number were available from a database at the University of Guelph. The hazard rate of removal from the herd was estimated using proportional hazard regression adjusted for intraherd correlation. Diagnosis of displaced abomasum significantly increased the hazarad rate of removal from the herd. For cows that were diagnosed with displaced abomasum the hazard rate of removal increased as parity increased. However...
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The Petrifilm HEC test (3M Canada Inc., London, Ontario), a quantitative microbiological test for Escherichia coli O157:H7, was evaluated for its performance as a beef-carcass monitoring test. Test repeatability and agreement and... more
The Petrifilm HEC test (3M Canada Inc., London, Ontario), a quantitative microbiological test for Escherichia coli O157:H7, was evaluated for its performance as a beef-carcass monitoring test. Test repeatability and agreement and agreement with an E. coli O157:H7 detection method using a hydrophobic grid membrane filter (HGMF) overlaid onto cefixime-tellurite-sorbitol MacConkey agar (CT-SMAC) followed by a latex agglutination test for the O157 antigen were determined by using pure cultures of E. coli O157:H7, beef samples experimentally contaminated with bovine feces containing E. coli O157:H7, and naturally contaminated beef carcasses of unknown E. coli O157:H7 status from a local abattoir. The Petrifilm HEC test showed excellent repeatability and excellent agreement with the HGMF-CT-SMAC method when test samples were obtained from pure cultures and experimentally contaminated meat. All 125 naturally contaminated beef carcasses surveyed were negative for E. coli O157:H7 with both m...
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The proximity of farms to badger setts was compared between farms that had experienced a tuberculosis breakdown and those that had not, over the 6 year period from 1988 to 1993. The data were derived from a badger removal study conducted... more
The proximity of farms to badger setts was compared between farms that had experienced a tuberculosis breakdown and those that had not, over the 6 year period from 1988 to 1993. The data were derived from a badger removal study conducted in East Offaly County in the Republic of Ireland. Badger removal began in 1989 and continued through 1993; by the end of 1990, approximately 80% of all badgers caught in the 6 year period had been removed. All badgers were examined, grossly, for evidence of tuberculosis. Tuberculosis status of the approximately 900 study herds was based on the results of the single intradermal comparative skin test and/or lesions of bovine tuberculosis. All herds were tested at least once annually. The number of herds experiencing bovine tuberculosis declined over the period, particularly in the years 1992 and 1993. The data on farm and badger sett location were stored and analysed, initially, in a geographical information system. Owing to the badger removal program...
Research Interests: Carnivora, Ireland, Logistic Regression, Multivariate Analysis, Preventive Veterinary Medicine, and 11 moreTuberculosis, Animals, Regression Analysis, Bovine Tuberculosis, Data Collection, Incidence, Cattle, Veterinary Sciences, Sensitivity and Specificity, Geographic Information System, and Tuberculin Test
Since Pearson’s linear correlation coefficient is not a complete and accurate description of the dependence structure between variables even when there exists a straight-line relationship between them, copulas as an alternative dependence... more
Since Pearson’s linear correlation coefficient is not a complete and accurate description of the dependence structure between variables even when there exists a straight-line relationship between them, copulas as an alternative dependence measure are described. Copulas allow modelling linear and non-linear dependence using any choice of marginal distributions. Since many families of copulas are known, the copula based approach provides flexibility in modelling and simulating data. We illustrate how to compute copula functions and use them to simulate data by considering a clinical trial of epileptic patients suffering from simple or complex partial seizures. A comparison with the correlation based analysis indicates that the suggested copula based methodology is more appropriate and is capable of modelling the skewed behaviour of measurements which the correlation model fails to do.