Mathematical approach towards non-stepwise performance assessment in HUASB reactor for wastewater treatment from pulp and paper mills

A lab-scale Hybrid Upflow Anaerobic Sludge Blanket (HUASB) reactor with a working volume of 6.5 litres has been taken for the performance analysis, in the treatability study of pulp and paper mill wastewater. In order to analyze the performance of the reactor, operational parameter like hydraulic retention time (HRT) was varied from 10, 20, 30 and 40 h. In addition to that, performance parameters like chemical oxygen demand (COD), pH, volatile fatty acids (VFA), alkalinity, gas production and VFA/alkalinity ratio are analyzed to check the reactor efficacy. The maximum COD removal efficiency of 81.3% is obtained at 40 h HRT, with gas production (methane content of 58%). Also, the obtained results are fitted to the kinetic models like the standard first order, first order and second order to evaluate the performance of the HUASB reactor

Mathematical approach towards non-stepwise performance assessment in HUASB reactor for wastewater treatment from pulp and paper mills

110-116A lab-scale Hybrid Upflow Anaerobic Sludge Blanket (HUASB) reactor with a working volume of 6.5 litres has been taken for the performance analysis, in the treatability study of pulp and paper mill wastewater. In order to analyze the performance of the reactor, operational parameter like hydraulic retention time (HRT) was varied from 10, 20, 30 and 40 h. In addition to that, performance parameters like chemical oxygen demand (COD), pH, volatile fatty acids (VFA), alkalinity, gas production and VFA/alkalinity ratio are analyzed to check the reactor efficacy. The maximum COD removal efficiency of 81.3% is obtained at 40 h HRT, with gas production (methane content of 58%). Also, the obtained results are fitted to the kinetic models like the standard first order, first order and second order to evaluate the performance of the HUASB reactor

Can Score Databanks Help Teaching?

Basic courses in most medical schools assess students' performance by conferring scores. The objective of this work is to use a large score databank for the early identification of students with low performance and to identify course trends based on the mean of students' grades. METHODOLOGY/PRINCIPAL FINDINGS: We studied scores from 2,398 medical students registered in courses over a period of 10 years. Students in the first semester were grouped into those whose ratings remained in the lower quartile in two or more courses (low-performance) and students who had up to one course in the lower quartile (high-performance). ROC curves were built, aimed at the identification of a cut-off average score in the first semesters that would be able to predict low performances in future semesters. Moreover, to follow the long-term pattern of each course, the mean of all scores conferred in a semester was compared to the overall course mean obtained by averaging 10 years of data. Individuals in the low-performance group had a higher risk of being in the lower quartile of at least one course in the second semester (relative risk 3.907; 95% CI: 3.378-4.519) and in the eighth semester (relative risk 2.873; 95% CI: 2.495-3.308). The prediction analysis revealed that an average score of 7.188 in the first semester could identify students that presented scores below the lower quartiles in both the second and eighth semesters (p<0.0001 for both AUC). When scores conferred by single courses were compared over time, three time-trend patterns emerged: low variation, upward trend and erratic pattern. CONCLUSION/SIGNIFICANCE: An early identification of students with low performance may be useful in promoting pedagogical strategies for these individuals. Evaluation of the time trend of scores conferred by courses may help departments monitoring changes in personnel and methodology that may affect a student's performance

Increased Corneal Epithelial Turnover Contributes to Abnormal Homeostasis in the Pax6(+/-) Mouse Model of Aniridia

We aimed to test previous predictions that limbal epithelial stem cells (LESCs) are quantitatively deficient or qualitatively defective in Pax6(+/-) mice and decline with age in wild-type (WT) mice. Consistent with previous studies, corneal epithelial stripe patterns coarsened with age in WT mosaics. Mosaic patterns were also coarser in Pax6(+/-) mosaics than WT at 15 weeks but not at 3 weeks, which excludes a developmental explanation and strengthens the prediction that Pax6(+/-) mice have a LESC-deficiency. To investigate how Pax6 genotype and age affected corneal homeostasis, we compared corneal epithelial cell turnover and label-retaining cells (LRCs; putative LESCs) in Pax6(+/-) and WT mice at 15 and 30 weeks. Limbal BrdU-LRC numbers were not reduced in the older WT mice, so this analysis failed to support the predicted age-related decline in slow-cycling LESC numbers in WT corneas. Similarly, limbal BrdU-LRC numbers were not reduced in Pax6(+/-) heterozygotes but BrdU-LRCs were also present in Pax6(+/-) corneas. It seems likely that Pax6(+/-) LRCs are not exclusively stem cells and some may be terminally differentiated CD31-positive blood vessel cells, which invade the Pax6(+/-) cornea. It was not, therefore, possible to use this approach to test the prediction that Pax6(+/-) corneas had fewer LESCs than WT. However, short-term BrdU labelling showed that basal to suprabasal movement (leading to cell loss) occurred more rapidly in Pax6(+/-) than WT mice. This implies that epithelial cell loss is higher in Pax6(+/-) mice. If increased corneal epithelial cell loss exceeds the cell production capacity it could cause corneal homeostasis to become unstable, resulting in progressive corneal deterioration. Although it remains unclear whether Pax6(+/-) mice have LESC-deficiency, we suggest that features of corneal deterioration, that are often taken as evidence of LESC-deficiency, might occur in the absence of stem cell deficiency if corneal homeostasis is destabilised by excessive cell loss