Nitrate and fluoride contamination in groundwater of an intensively managed agroecosystem: A functional relationship

A study was conducted to assess the potential of nitrate-nitrogen (NO₃-N) and fluoride (F) contamination in drinking groundwater as a function of lithology, soil characteristics and agricultural activities in an intensively cultivated district in India. Two hundred and fifty two groundwater samples were collected at different depths from various types of wells and analyzed for pH, electrical conductivity (EC), NO₃-N load and F content. Database on lithology, soil properties, predominant cropping systems, fertilizer and pesticide uses were also recorded for the district. The NO₃-N load in groundwater samples were low ranging from 0.12 to 6.58 μg mL^− 1 with only 8.7% of them contained greater than 3.0 μg mL^− 1 well below the 10 μg mL^− 1, the threshold limit fixed by WHO for drinking purpose. Samples from the habitational areas showed higher NO₃-N content over the agricultural fields. The content decreased with increasing depth of wells (r = − 0.25, P ≤ 0.01) and increased with increasing rate of nitrogenous fertilizer application (r = 0.90, P ≤ 0.01) and was higher in areas where shallow- rather than deep-rooted crops (r = − 0.28, P = ≤ 0.01, with average root depth) are grown. The NO₃-N load also decreased with increasing bulk density (r = − 0.73, P ≤ 0.01) and clay content (r = − 0.51, P ≤ 0.01) but increased with increasing hydraulic conductivity (r = 0.68, P ≤ 0.01), organic C (r = 0.78, P ≤ 0.01) and potential plant available N (r = 0.82, P ≤ 0.01) of soils. Fluoride content in groundwater was also low (0.02 to 1.15 μg mL^− 1) with only 4.0% of them exceeding 1.0 μg mL^− 1 posing a potential threat of fluorosis. On average, its content varied little spatially and along depth of sampling aquifers indicating little occurrence of F containing rocks/minerals in the geology of the district. The content showed a significant positive correlation (r = 0.234, P = ≤ 0.01) with the amount of phosphatic fertilizer (single super phosphate) used for agriculture. Results thus indicated that the groundwater of the study area is presently safe for drinking purpose but some anthropogenic activities associated with intensive cultivation had a positive influence on its loading with NO₃-N and F.     

An Algorithmic Approach to the Identification of Rigid Domains in Proteins

Many proteins undergo conformational changes to perform their functions. A simple mechanism of conformational change in proteins is a rigid domain motion, in which two parts of a structure move rigidly with respect to each other. The identification of rigid domains is therefore useful in understanding the structure-function relationship of proteins. Many algorithms, including those in [16], [22], [13], [10], and [19], have been developed to identify rigid domains. In this paper we complement these works by proposing a mathematical definition of a rigid domain. We argue that our definition more accurately captures the intuitive notion of rigid domain in the previous work, than the quantitative definition of a rigid domain introduced by Nichols et al. [19]. Furthermore, our definition admits a practical approximation algorithm. We can prove theoretical guarantee on the quality of the output of our algorithm. We implement a randomized version of our algorithm, and demonstrate its effectiveness on several known protein complexes.     

Kinetics of the Kreis test through response surface methodology

The Kreis test is one of the procedures for early detection of oxidative products of fats and oils. The reaction is complicated, sensitive and continuous. The kinetics of the Kreis test have been studied as a function of reagent, phloroglucinol, oil quantity and incubation period for three oils with different fatty acid profiles, storage life and presence of compounds other than triglycerides. A central composite rotatable design with each factor at five levels required 20 experiments for each oil. The results of experiments carried out in duplicate have been examined by analysis of variance, and polynomials of appropriate degree were fitted to the data. The polyhedron search method was used to compute optimum conditions for carrying out the test for each oil. Three-dimensional graphs were generated to bring out the differences in the oils and the kinetics for each oil. Though “compromised” optimized conditions have been reported, the results indicate the necessity of more detailed investigation into the reaction.     

Bi-objective approach for computer-aided diagnosis of schizophrenia patients using fMRI data

Multimedia Tools and Applications - Computer-aided diagnosis (CAD) of schizophrenia based on the analysis of brain images, captured using functional Magnetic Resonance Imaging (fMRI) technique, is...