In an attempt to evaluate the environmental quality of Marsa-Matrouh city which covered the most famous beaches in Egypt, an environmental risk assessment was performed, including a screening level ecological risk ass...In an attempt to evaluate the environmental quality of Marsa-Matrouh city which covered the most famous beaches in Egypt, an environmental risk assessment was performed, including a screening level ecological risk assessment. The aim of this work was to determine which metals could possibly pose toxic adverse ecological effects to marine organisms and to determine whether hot spots exist or not. To fulfill the goals of study, surfacial sediment and water samples were collected from ten different locations covering Marsa-Matrouh city during four seasons (2010-2011). The average concentrations of Cd, Cu, Fe, Ni, Pb and Zn were 2.381 ± 3.389, 9.307 ± 14.159, 68.969 ± 9.397, 2.642 ± 1.004, 16.712 ± 8.469, 31.168 ± 15.322 μg/l in water and 0.755 ± 0.240, 5.363 ± 1.581, 962.131 ± 975.084, 3.972 ± 2.180, 15.210 ± 4.434 and 24.608 ± 7.706 μg/g dry weight in sediment respectively. The concentrations of the investigated six metals in water were within the acceptable limits except for two stations (Cleopatra and El-Obayed) which exhibited higher values than the permissible level of Cd during autumn 2010. Metal pollution assessment for both water and sediment was studied. Heavy metal pollution index indicates that water is not critically polluted with respect to the investigated metals. For sediment samples, threshold effect concentrations (TEC HQ) were lower than 1 except for Cd which showed higher value than 1, indicating the possibility of occurrence of toxic adverse ecological effects to benthic organisms for Cd, while rare adverse ecological effects are expected to occur with respect to Cu, Ni, Pb and Zn.展开更多
The recent explosion of high-throughput technology has been accompanied by a corresponding rapid increase in the number of new statistical methods for developing prognostic and predictive signatures. Three commonly us...The recent explosion of high-throughput technology has been accompanied by a corresponding rapid increase in the number of new statistical methods for developing prognostic and predictive signatures. Three commonly used feature selection techniques for time-to-event data: single gene testing (SGT), Elastic net and the Maximizing R Square Algorithm (MARSA) are evaluated on simulated datasets that vary in the sample size, the number of features and the correlation between features. The results of each method are summarized by reporting the sensitivity and the Area Under the Receiver Operating Characteristic Curve (AUC). The performance of each of these algorithms depends heavily on the sample size while the number of features entered in the analysis has a much more modest impact. The coefficients estimated utilizing SGT are biased towards the null when the genes are uncorrelated and away from the null when the genes are correlated. The Elastic Net algorithms perform better than MARSA and almost as well as the SGT when the features are correlated and about the same as MARSA when the features are uncorrelated.展开更多
文摘In an attempt to evaluate the environmental quality of Marsa-Matrouh city which covered the most famous beaches in Egypt, an environmental risk assessment was performed, including a screening level ecological risk assessment. The aim of this work was to determine which metals could possibly pose toxic adverse ecological effects to marine organisms and to determine whether hot spots exist or not. To fulfill the goals of study, surfacial sediment and water samples were collected from ten different locations covering Marsa-Matrouh city during four seasons (2010-2011). The average concentrations of Cd, Cu, Fe, Ni, Pb and Zn were 2.381 ± 3.389, 9.307 ± 14.159, 68.969 ± 9.397, 2.642 ± 1.004, 16.712 ± 8.469, 31.168 ± 15.322 μg/l in water and 0.755 ± 0.240, 5.363 ± 1.581, 962.131 ± 975.084, 3.972 ± 2.180, 15.210 ± 4.434 and 24.608 ± 7.706 μg/g dry weight in sediment respectively. The concentrations of the investigated six metals in water were within the acceptable limits except for two stations (Cleopatra and El-Obayed) which exhibited higher values than the permissible level of Cd during autumn 2010. Metal pollution assessment for both water and sediment was studied. Heavy metal pollution index indicates that water is not critically polluted with respect to the investigated metals. For sediment samples, threshold effect concentrations (TEC HQ) were lower than 1 except for Cd which showed higher value than 1, indicating the possibility of occurrence of toxic adverse ecological effects to benthic organisms for Cd, while rare adverse ecological effects are expected to occur with respect to Cu, Ni, Pb and Zn.
文摘The recent explosion of high-throughput technology has been accompanied by a corresponding rapid increase in the number of new statistical methods for developing prognostic and predictive signatures. Three commonly used feature selection techniques for time-to-event data: single gene testing (SGT), Elastic net and the Maximizing R Square Algorithm (MARSA) are evaluated on simulated datasets that vary in the sample size, the number of features and the correlation between features. The results of each method are summarized by reporting the sensitivity and the Area Under the Receiver Operating Characteristic Curve (AUC). The performance of each of these algorithms depends heavily on the sample size while the number of features entered in the analysis has a much more modest impact. The coefficients estimated utilizing SGT are biased towards the null when the genes are uncorrelated and away from the null when the genes are correlated. The Elastic Net algorithms perform better than MARSA and almost as well as the SGT when the features are correlated and about the same as MARSA when the features are uncorrelated.
