Three-dimensional image classification using hierarchical spatial decomposition: A study using retinal data

This thesis describes research conducted in the field of image mining especially volumetric image mining. The study investigates volumetric representation techniques based on hierarchical spatial decomposition to classify three-dimensional (3D) images. The aim of this study was to investigate the effectiveness of using hierarchical spatial decomposition coupled with regional homogeneity in the context of volumetric data representation. The proposed methods involve the following: (i) decomposition, (ii) representation, (iii) single feature vector generation and (iv) classifier generation. In the decomposition step, a given image (volume) is recursively decomposed until either homogeneous regions or a predefined maximum level are reached. For measuring the regional homogeneity, different critical functions are proposed. These critical functions are based on histograms of a given region. Once the image is decomposed, two representation methods are proposed: (i) to represent the decomposition using regions identified in the decomposition (region-based) or (ii) to represent the entire decomposition (whole image-based). The first method is based on individual regions, whereby each decomposed sub-volume (region) is represented in terms of different statistical and histogram-based techniques. Feature vector generation techniques are used to convert the set of feature vectors for each sub-volume into a single feature vector. In the whole image-based representation method, a tree is used to represent each image. Each node in the tree represents a region (sub-volume) using a single value and each edge describes the difference between the node and its parent node. A frequent sub-tree mining technique was adapted to identified a set of frequent sub-graphs. Selected sub-graphs are then used to build a feature vector for each image. In both cases, a standard classifier generator is applied, to the generated feature vectors, to model and predict the class of each image. Evaluation was conducted with respect to retinal optical coherence tomography images in terms of identifying Age-related Macular Degeneration (AMD). Two types of evaluation were used: (i) classification performance evaluation and (ii) statistical significance testing using ANalysis Of VAriance (ANOVA). The evaluation revealed that the proposed methods were effective for classifying 3D retinal images. It is consequently argued that the approaches are generic

Steady improvement of infection control services in six community hospitals in Makkah following annual audits during Hajj for four consecutive years

BACKGROUND: the objective of this study was to evaluate the impact of annual review of the infection control practice in all Ministry of Health hospitals in the holy city of Makkah, Saudi Arabia, during the Hajj period of four lunar Islamic years, 1423 to 1426 corresponding to 2003 to 2006. METHODS: audit of infection control service was conducted annually over a 10-day period in six community hospitals with bed capacities ranging from 140 to 557 beds. Data were collected on standardized checklists on various infection control service items during surprise visits to the medical, pediatric, surgical, and critical care units, and the kitchens. Percentage scores were calculated for audited items. The results of the audit for hospitals were confidentially sent to them within four weeks after the end of Hajj. RESULTS: deficiencies observed in the first audit included lack of infection control committees, infection control units, infection control educational activities, and surveillance system and shortage of staff. These deficiencies were resolved in the subsequent audits. The average (range) scores of hospitals in 11 infection control items increased from 43% (20–67%) in the first audit to 78% (61–93%) in the fourth audit. CONCLUSION: regular hospital infection control audits lead to significant improvement of infection control practice. There is a need to build a rigorous infection control audit into hospitals' ongoing monitoring and reporting to the Ministry of Health and to provide these hospitals with feed back on such audits to continuously strengthen the safety standards for patients, visitors, and employees

Biomimetic Whitening Effect of Polyphosphate-Bleaching Agents on Dental Enamel.

This in vitro study investigated the extrinsic tooth-whitening effect of bleaching products containing polyphosphates on the dental enamel surface compared to 10% carbamide peroxide (CP). Eighty human molars were randomly allocated into four whitening-products groups. Group A (control) was treated with 10% CP (Opalescence). The other groups with non-CP over-the-counter (OTC) products were group B = polyphosphates (iWhiteWhitening-Kit); group C = polyphosphates+fluoride (iWhite-toothpaste); and group D = sodium bicarbonate (24K-Whitening-Pen). L*, a*, b* color-parameters were spectrophotometer-recorded at baseline (T0), one day (T1), and one month (T2) post-treatment. Changes in teeth color (ΔEab) were calculated. Data were analyzed using ANOVA and the Bonferroni test (α = 0.05). Groups A, B, and D showed significant differences in ΔL*&Δa* parameters at T1, but not in Δb* at T0. Group C showed no difference for ΔL*, Δa*, Δb* at T0 and T1. Group A showed differences for ΔL*, Δa*, Δb*, at T2, while groups B, C, and D had no difference in any parameters at T0. At T1, ΔEab values = A > D> B > C (ΔEab = 13.4 > 2.4 > 2.1 > 1.2). At T2, ΔEab values increased = A > B > C > D (ΔEab = 12.2 > 10.6 > 9.2 > 2.4). In conclusion, the 10% CP and Biomimetic polyphosphate extrinsic whitening kit demonstrated the highest color change, while simulated brushing with dark stain toothpaste and a whitening pen demonstrated the lowest color change at both measurement intervals

Causes of admission to intensive care units in the Hajj period of the Islamic year 1424 (2004).

<b>Background: </b>Approximately 2 to 3 million pilgrims perform Hajj every year. We describe the pattern of diseases, complications, and outcome of pilgrims who required admission to intensive care units (ICUs) during the Hajj period of the Islamic year 1424 (2004). <b> Methods: </b>This was a cross-sectional study of all patients admitted to 104 ICU beds in four hospitals in Mena and three hospitals in Arafat during the Hajj. <b>Results: </b>Of 140 patients admitted to ICUs, 75 (54&#x0025;) patients were older than 60 years. The risk of complications and death increased with age, with the highest risk noticed among pilgrims older than 80 years. Ninety- four (67.6&#x0025;) patients were men. Eighty-nine (63.6&#x0025;) patients were admitted with cardiovascular diseases and 37 (26.4&#x0025;) patients with infections. Myocardial infarction (25&#x0025;) and pneumonia (22&#x0025;) were the most common admitting diagnoses. Trauma accounted for only 6.4&#x0025; (9 patients) of admissions. Sixty-three (45.0&#x0025;) patients recovered and were discharged or transferred to hospital wards in stable condition, 40 (28.6&#x0025;) were transferred to tertiary care centers for specialized services, 21 (15.0&#x0025;) were transferred to tertiary care centers after closure of the temporary hospitals in Mena and Arafat, 15 (10.7&#x0025;) patients died, and one (0.7&#x0025;) patient was discharged against medical advice. <b>Conclusion: </b>This study revealed information on the pattern of diseases and the most common causes of admission of pilgrims to ICUs and the required medical services during Hajj. It is hoped that this information will be of help to health care planners and officials to provide optimal and cost effective health care services to pilgrims in Hajj

Causes of hospitalization of pilgrims in the Hajj season of the Islamic year 1423 (2003)

<b>Background: </b> Approximately 2 to 3 million pilgrims perform Hajj every year. Planning for health care requires knowledge of the pattern of dis-eases, complications, and outcome of pilgrims who require hospitaliza-tion during the Hajj period. <b> Methods: </b> In a cross-sectional study we compiled data on all patients admitted to 1487 beds in four hospitals in Mena (793 beds) and three hos-pitals in Arafat (694 beds) from the seventh to the thirteenth day of the Hajj season of the Islamic year 1423, corresponding to 8 to 14 February 2003. <b> Results: </b> Of 808 patients hospitalized, most (79&#x0025;) were older than 40 years. There was no sex preponderance. A total of 575 (71.2&#x0025;) patients were admitted to medical wards, 105 (13.0&#x0025;) to surgical wards, and 76 (9.4&#x0025;) to intensive care units. Most patients (84.8&#x0025;) had one acute medical problem. Pneumonia (19.7&#x0025;), ischemic heart disease (12.3&#x0025;), and trauma (9.4&#x0025;) were the most common admitting diagnoses. More than one third (39&#x0025;) had co-morbid conditions. A total of 644 (79.7&#x0025;) pa-tients were discharged from the hospital in stable condition to continue therapy in their residential camps, 140 (17.3&#x0025;) were transferred to other hospitals in Makkah for specialized services or further care, 19 (2.3&#x0025;) were discharged against medical advice, and 5 (0.7&#x0025;) patients died. <b> Conclusion: </b> This study provided information on the most common causes of hospitalization, pattern of diseases, and required medical ser-vices for pilgrims in Hajj. It is hoped that this data will be of help to health sector planners and officials to provide optimal and cost-effective health care services to pilgrims in Hajj

Demographic risk factors for extra-pulmonary tuberculosis among adolescents and adults in Saudi Arabia.

Despite low infectious potential of extrapulmonary tuberculosis (EPTB), it poses significant clinical challenges in terms of diagnosis and treatment monitoring. Understanding the main demographical risk factors for disease characteristics of EPTB plays a crucial role in speeding up diagnosis process and improving overall clinical experience. The aim of this study was to investigate the main demographical and clinical risk factors for EPTB among adults and adolescents for the first time in Saudi Arabia. A cross-sectional multicenter study was carried out on a collection of 902 extrapulmonary Mycobacterium tuberculosis complex (MTBC) isolates with demographical and clinical data. All isolates were subjected to spoligotyping and 24-loci based MIRU-VNTR typing. The association between two potential variables was assessed using odd ratios (OR) calculations. Independent risk factors for EPTB and diseases characteristics of EPTB were identified using multivariate regression model analyses. Gender was found to be significantly associated with lymph node, gastrointestinal, central nervous system and urogenital TB. Lymph node TB showed statistical association to age group below 25 years, non-Saudis and South East Asian ethnicity. While gastrointestinal TB demonstrated an association with patients above 60 years old, and Saudis. Multivariate analysis showed that gender is an independent risk factor to urogenital TB (p 0.03) and lymph node TB (p 0.005). On the other hands, South Asian (p 0.01) and South East Asian (p 0.03) ethnicities were both identified as independent risk factors significantly associated with EPTB. MTBC lineages, site of infections, gender, HIV and smear positivity showed no significant association. Nationwide qualitative-studies are highly warranted in the future to further understand the main demographic risk factors for disease characteristics of EPTB