ABSTRACT
Reduction of bias in remotely sensed precipitation products is a major challenge in environment modeling, hydrology, and managing the water resources. Various bias correction techniques are applied to reduce the bias from pixel to gauge data. However, a successful methodology to improve bias correction on the daily scale is often challenging and limited. We present a methodology that can be used to correct the daily bias in remote sensing rainfall data, and to demonstrate the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) 3B42 data was used. The proposed bias correction method is based on the concept of similarity (homogeneous) conditions developed based on the periodicity and different percentile-based precipitation amount, and by identifying the best donor pixel to transfer bias correction factor to a specific ungauged pixel (the receptor pixel) based on the similarity (elevation, latitude, and longitude). Bias correction factors were obtained using the mean bias-removal (MBR) and multiplicative ratio (MR) techniques in the cells of the similarity matrix. The proposed methodology demonstrates a significant removal of bias associated with TMPA 3B42 data sets and it is capable of removing the bias in daily precipitation data on an average by 57% (51%) in the gauged pixels, and 25% (22%) in the ungauged pixels for MBR (MR) method.
ABSTRACT
BACKGROUND: Oxidative stress affects women fertility and influences on the sperm quality by alterating activities of cholinesterases, a molecular marker of stress-related infertility. The aim of the present study was to investigate the role of acetyl-cholinesterase (AChE), butyrylcholinesterase (BuChE) activities and phenotypes in patients with unexplained infertility (idiopathic). It's possible association with inflammation marker C-reactive protein (CRP) and other oxidative stress markers, i.e. before and after intra uterine insemination (IUI). METHODS: In this study, blood samples of 60 patients with unexplained infertility were collected the day before and 24 hr after IUI (between 8 AM and 9 AM after the overnight fasting) and activities of BuChE, AChE, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GpX) and serum levels of thiol proteins (TP), C-reactive protein (CRP), total antioxidant capacity (TAC) were measured. Statistical significance was assumed at p<0.05. RESULTS: Before IUI, there was a significant (p=0.048) positive correlation between BuChE activity and plasma TAC and a significant difference in the CAT activity between various BuChE (UU and non-UU) phenotypes. However, after IUI, a significant negative correlation between the AChE activity and BuChE activity was found (p=0.045) and the level of RBC AChE activity was significantly reduced (382.4± 163.19 vs. 586.7±384 IU/grHb, p=0.025). Meanwhile, after IUI, the activities of SOD (1568±847.5 IU/grHb vs. 1126±229.3, p=0.031) and CAT (310±53.4 IU/grHb vs. 338±73, p=0.025) were increased. CONCLUSION: This study suggests that decline in cholinesterases activities may be responsible for stimulation of oxidative stress and inflammation and reduction in fertility rates by IUI.