Ichthyofaunal Diversity of Dhansiri River, Dimapur, Nagaland, India

Northeastern India, one of the Ichthyofaunal hot spot areas of our country, is marked by the presence of varied freshwater fishes,a few adapted to torrential waterflow. River Dhansiri is an important river of Dimapur District of Nagaland, India, which flows through Nagaland –Assam border harbouring rich aquatic flora and fauna. Very little studies have been carried out to document the fish biodiversity of the Dhansiri river till date. In the present study an attempt has been made to access the piscine diversity of this river. The survey results in finding of species of 34 fishes belonging to five (5) orders, thirteen (13) families and twenty four (24) genera. Cyprniformes is the dominant order while Osteoglossiformes is the least common

Learning in presence of class imbalance and class overlapping by using one-class SVM and undersampling technique

The class imbalance problem engraves the traditional learning models by degrading performance and yielding erroneous outcomes. It is the scenario where one of the class representation is over-shadowed by other classes in a data space. Presence of class imbalance can cause a grave difficulty as misclassification cost of minority class tends to be very high. Presence of overlapping cases along with the case of imbalanced data, can lead to create grim situation for effective learning. In this study, an in-depth analysis of the effects of class imbalance and class overlapping in conventional learning models has been presented. A data level approach is adapted with one-class SVM-based anomaly detection to detect the cases of data overlapping while an adapted Tomek-link undersampling algorithm is defined to treat both overlapped and imbalanced cases. The proposed model evolves to eliminate borderline, redundant and overlapping cases with the account of Tomek-link pair and sparse neighbourhood. The proposed method has been evaluated with six state-of-the-art models for seven binary and two multiclass datasets, with respect to three standard learning models. The proposed model has been evaluated with cost-sensitive learning and extreme learning based approaches for imbalanced class learning. The proficiency of the proposed method over state-of-the-art models is established through experimental analyses

The effect of Lewis acidity in carbonyl coupling reactions

938-940Relative Lewis acidities of (+)-Pr(hfc)3, (+)-Eu(hfc)3 and (+)Yb(hfc)3 have been estimated by measuring the induced chemical shift of the aldehydic proton of benzaldehyde in the presence of these lanthanide complexes. The order has been estimated as Pr(hfc)3 > Yb(hfc)3 >>Eu(hfc)3. These lanthanide complexes and a few other non-lanthanide compounds such as BBr3, BF3, OEt2, TiCl4 and SnCl4 have been used as Lewis acid catalysts in a coupling reaction between an aldehyde and (E)-1-methoxy-1-(trimethylsilyloxy)propene. Results show that the chemical yield of the reaction is in the same order as the Lewis acidity of the catalyst used. The observation is in consonant with the expectation that higher is the Lewis acidity more should be degree of activation of the carbonyl base by the Lewis acid