Atsu S.S. Dorvlo

Solar radiation estimation using artificial neural networks

Artificial Neural Network Methods are discussed for estimating solar radiation by first estimating the clearness index. Radial Basis Functions, RBF, and Multilayer Perceptron, MLP, models have been investigated using long-term data from eight stations in Oman. It is shown that both the RBF and MLP models performed well based on the root-mean-square error between the observed and estimated solar radiations. However, the RBF models are preferred since they require less computing power. The RBF model, obtained by training with data from the meteorological stations at Masirah, Salalah, Seeb, Sur, Fahud and Sohar, and testing with those from Buraimi and Marmul, was the best. This model can be used to estimate the solar radiation at any location in Oman.

Estimating wind speed distribution

The Weibull distribution is used to model wind speeds at four locations in Oman. The scale and shape parameters were estimated using three methods, the Chi-square method, method of moments and regression method. It was observed that the estimates using the Chi-squared method gave the best overall fit to the distribution of the wind data. Both the scale and shape parameters varied widely over the months.

Estimation of solar radiation from the number of sunshine hours

Several expressions have been used to estimate global solar radiation from sunshine hours for weather stations in Oman, an arid region. These included original (linear) and modified (linear-logarithmic) Angstrom-Black type regression functions, a quadratic function, a power relationship, a power-trigonometric equation and one from a new Angstrom-Black type logarithmic model. For the power-trigonometric model, the solar altitude of the station was used as additional information for estimating the solar radiation. All the models performed well as estimators of global solar-radiation from sunshine hours but the non-linear models were better than the basic linear model. The power-trigonometric model estimated the radiation values best. The quadratic and linear-logarithmic models are the preferred models when only the relative sunshine is used.

Perception of and attitude towards mental illness in Oman

Background: As conceptions of mental illness are often dictated by prevailing socio-cultural factors and the philosophy of the time, there is little research to substantiate how mental illness is perceived in the Arab world in the light of both traditional and more recent modernization and acculturation processes. Aims: To examine whether social factors exert an influence on a persons attitude towards people with mental illness (PWMI) in the rapidly changing country of Oman. Methods: This study compares the response elicited from medical students, relatives of psychiatric patients and the general Omani public on the causes of mental illness, attitudes toward PWMI and the care and management of people with mental illness. Results: This study found no relationship between attitudes towards PWMI, and demographic variables such as age, educational level, marital status, sex and personal exposure to people with mental illness. Both medical students and the public rejected a genetic factor as the cause of mental illness; instead they favoured the role of spirits as the aetiological factor for mental illness. There were favourable responses on statements regarding value of life, family life, decision-making ability, and the management and care of mental illness. However, both medical students and the public thought that PWMI tend to have peculiar and stereotypical appearances and the majority preferred that facilities for psychiatric care should be located away from the community. Although the relatives of psychiatric patients were concerned about the welfare of mental patients, their responses varied and were often contingent upon their expectations. Conclusions: The data suggest that neither socio-demographic factors nor previous exposure to PWMI was related to attitudes towards PWMI. Although the attitudes of Omanis toward PWMI appear to fluctuate in complex ways, traditional beliefs on mental illness have yet to be eroded by exposure to a biomedical model of mental illness. This study largely supports the view that the extent of stigma varies according to the cultural and sociological backgrounds of each society.

Presence and Severity of Anorexia and Bulimia Among Male and Female Omani and Non-Omani Adolescents

OBJECTIVE The population of Oman is a heterogeneous mix of nationalities providing a natural setting for studying the cross-cultural differences in the presence and severity of eating disorders as well as an opportunity for evaluating the performance of measurement instruments for these disorders. METHOD Disordered eating screening instruments (the Eating Attitude Test and the Bulimic Investigatory Test) were administered to Omani teenagers, non-Omani teenagers, and Omani adults. RESULTS On the Eating Attitude Test, 33% of Omani teenagers (29.4% females and 36.4% males) and 9% of non-Omani teenagers (7.5% of males and 10.6% females) showed a propensity for anorexic-like behavior. On the Bulimic Investigatory Test, 12.3% of Omani teenagers showed a propensity for binge eating or bulimia (13.7% females and 10.9% males). Among the non-Omani teenagers, 18.4% showed a tendency toward bulimia, with females showing a slightly greater tendency than males. In contrast, barely 2% of Omani adults showed either a presence of or a severity of disorderly behavior with food. CONCLUSION Omani teenagers scored significantly higher than other ethnic groups and Omani adults. This finding is discussed in the light of emerging evidence from many parts of the world suggesting that cultural transition, compounded by demographic constraints, plays a significant role in abnormal eating attitudes.

Eating attitudes and body dissatisfaction in adolescents: Cross‐cultural study

Aims:  Sociocultural factors are thought to be important in the pathogenesis of eating disorders. However, there have been few studies comparing eating behavior among various cultural populations. The aim of the present study is to compare attitudes towards bodyweight and shape, and desire for thinness in Japanese male and female subjects with those in people from other countries and of different ethnic origin.

Functional outcomes following anoxic brain injury: a comparison with traumatic brain injury

Primary objective: To compare the functional outcomes of patients with anoxic brain injury (ABI) and patients with traumatic brain injury (TBI) following inpatient rehabilitation. Research design: Retrospective chart review. Methods and procedures: Data on 68 patients with brain injury (34 with ABI and 34 with TBI) were collected. Main outcomes and results: The ABI and TBI groups were demographically similar, except that patients with ABI were more likely to be married. Both groups significantly improved their function and were similar upon discharge. For the ABI group, there were trends toward a shorter length of stay, increased total FIM efficiency and decreased cost of stay when compared with the TBI group. The patients with ABI tended to be discharged to a sub-acute rehabilitation facility more than those in the TBI group. Conclusions: This study is important because it shows that patients with ABI benefit from inpatient rehabilitation and made significant functional gains comparable to the gains of patients with TBI.

Monthly average daily solar radiation and clearness index contour maps over Oman

Using meteorological data spanning more than ten years in Oman, radial basis function neural networks were developed for estimation of the solar radiation and clearness index for any location in Oman, given its longitude, latitude, altitude, sunshine hours and month of the year. Data generated for 25 different locations were then used to plot contour maps for monthly average daily solar radiation and clearness index over Oman. These maps will serve as a much needed reference for design and performance evaluation of solar energy conversion systems in this region.

A survey of anorexia nervosa using the Arabic version of the EAT-26 and “gold standard” interviews among Omani adolescents

Objective: The purpose of this study was to assess the validity of the Eating Attitude Test (EAT) in identifying the presence and severity of eating pathology in male and female Omani urban adolescents and to establish cut-off scores that matched those of anorexia identified by gold standard interviews without fear of fatness criteria. Methods: Both females (n=126) and males (n=136) were screened using the Arabic version of the EAT- 26 and interviewed using a semi-structured, Composite International Diagnostic Interview (CIDI) in order to investigate the relationship between false positives and false negatives at various EAT-26 cut-off points. A receiver operating characteristics (ROC) curve was calculated to discriminate the power of the EAT-26 for every possible threshold score. Results: The EAT-26 identified 29% of the subjects as probable anorexic cases as against 9.5% identified during the structured interview based on the anorexia gold standard (32% males and 68% females). The sensitivity and specificity of the EAT-26 were respectively 24% and 69.6%. When using the ROC curve, a cut-off score of 10 gave the best compromise between sensitivity (64%) and specificity (38%). Discussion: Although the EAT-26 is the most widely used screening instrument in cross-cultural studies, it does not appear to be reliable in identifying probable cases of anorexia among Omani adolescents. The use of a gold standard interview without fat phobia criteria indicated that the rate of anorexia nervosa may be more prevalent among males than previously estimated. This intriguingly high preponderance of males is discussed in terms of prevailing demographic trends in Oman.

The detection of mood and anxiety in people with epilepsy using two-phase designs: Experiences from a tertiary care centre in Oman

BACKGROUND The detection of mood and anxiety disorders is of great clinical importance in patients with chronic disease but data on the occurrence of affective dysfunction is lacking among people with epilepsy (PWE) in non-western populations. Further compounding such situation, the validity of some of the common assessment measures has not been examined. OBJECTIVE The study aims to investigate the application of the Hospital Anxiety and Depression Scale (HADS) by identifying patients with comorbid affective dysfunctions in an Omani population. The semi structured interview, Composite International Diagnostic Interview (CIDI) will be used to establish the psychometric property of HADS in the Omani population. METHODS PWE (n=150) were screened with the semi-structured, (CIDI) and the HADS. A receiver operating characteristics (ROC) curve was calculated to discriminate the power of the HADS for every possible threshold score. RESULTS The semi-structured interview revealed the prevalence rate of 27% for depressive disorder and 45% for anxiety disorder. The best compromise using, the cut-off score of 7 or 8, gave a sensitivity of 99% for depression and 83-91% for anxiety and a specificity of 87.5-100% for depression and 85-94% for anxiety. CONCLUSIONS Findings suggest that HADS is a useful screening tool for this particular population. This finding is discussed from the socio-cultural perspective of Omani society.