North Eastern Hill University

About: North Eastern Hill University is a education organization based out in Shillong, Meghalaya, India. It is known for research contribution in the topics: Population & Catalysis. The organization has 2318 authors who have published 4476 publications receiving 48894 citations.

Global Optimization by Differential Evolution and Particle Swarm Methods: Evaluation on Some Benchmark Functions

Abstract: In this paper we compare the performance of the Differential Evolution (DE) and the Repulsive Particle Swarm (RPS) methods of global optimization. To this end, seventy test functions have been chosen. Among these test functions, some are new while others are well known in the literature; some are unimodal, the others multi-modal; some are small in dimension (no. of variables, x in f(x)), while the others are large in dimension; some are algebraic polynomial equations, while the other are transcendental, etc. FORTRAN programs of DE and RPS have been appended. Among 70 functions, a few have been run for small as well as large dimensions. In total, 73 optimization exercises have been done. DE has succeeded in 65 cases while RPS has succeeded in 55 cases. In almost all cases, DE has converged faster and given much more accurate results. The convergence of RPS is much slower even for lesser stringency on accuracy. Some test functions have been hard for both the methods. These are: Zero-Sum (30D), Perm#1, Perm#2, Power-sum, and Bukin-6 functions. From what we find, one cannot reach at the definite conclusion that the DE performs better or worse than the RPS. None could assure a supremacy over the other. Each one faltered in some cases; each one succeeded in some others. However, DES is unquestionably faster, more accurate and more frequently successful than the RPS. It may be argued, nevertheless, that alternative choice of adjustable parameters could have yielded better results in either method's case. The protagonists of either method could suggest that. Our purpose is not to join with the one or the other. We simply want to highlight that in certain cases they both succeed, in certain other case they both fail and each one has some selective preference over some particular type of surfaces. What is needed is to identify such structures and surfaces that suit a particular method most. It is needed that we find out some criteria to classify the problems that suit (or does not suit) a particular method. This classification will highlight the comparative advantages of using a particular method for dealing with a particular class of problems.

Functional ureogenesis and adaptation to ammonia metabolism in Indian freshwater air-breathing catfishes

Abstract: The Indian freshwater air-breathing catfishes Heteropneustes fossilis and Clarias batrachus are hardy and capable of living in derelict water bodies and tolerating temporary water deprivation. Several studies have been made on their ureogenic adaptations, ureogenic metabolic machinery, and regulation under different physiological and environmental conditions. Both species are potentially ureogenic teleosts expressing the complete repertoire of ornithine-urea cycle (OUC) enzymes, not only in hepatic tissue but also in certain non-hepatic tissues. This review compiles the information available on the peculiarities of their ureogenic machinery and the induction of ureogenesis during adaptation to various stressful conditions such as exposure to high environmental ammonia, water deprivation, highly alkaline environment, etc. The biochemical profile and pattern of physiological adaptations, suggesting an intermediary status of these fishes in the evolution of ureotely in vertebrates, is discussed.

From jhum to broom: Agricultural land-use change and food security implications on the Meghalaya Plateau, India.

Abstract: Human population growth in the developing world drives land-use changes, impacting food security. In India, the dramatic change in demographic dynamics over the past century has reduced traditional agricultural land-use through increasing commercialization. Here, we analyze the magnitude and implications for the farming system by the introduction of cash-cropping, replacing the traditional slash and burn rotations (jhum), of the tribal people on the Meghalaya Plateau, northeast India, by means of agricultural census data and field surveys conducted in seven villages. Land-use change has brought major alterations in hill agricultural practices, enhanced cash-cropping, promoted mono-cropping, changed food consumption patterns, underpinned the emergence of a new food system, and exposed farmers and consumers to the precariousness of the market, all of which have both long- and short-term food security implications. We found dietary diversity to be higher under jhum compared to any of the cash-crop systems, and higher under traditional cash-cropping than under modern cash-cropping.