Fractal and Multifractal Analysis of the Rise of Oxygen in Earth's Early Atmosphere

The rise of oxygen in Earth's atmosphere that occurred 2.4 to 2.2 billion years ago is known as the Earth's Great Oxidation, and its impact on the development of life on Earth has been profound. Thereafter, the increase in Earth's oxygen level persisted, though at a more gradual pace. The proposed underlying mathematical models for these processes are based on physical parameters whose values are currently not well-established owing to uncertainties in geological and biological data. In this paper, a previously developed model of Earth's atmosphere is modified by adding different strengths of noise to account for the parameters' uncertainties. The effects of the noise on the time variations of oxygen, carbon and methane for the early Earth are investigated by using fractal and multifractal analysis. We show that the time variations following the Great Oxidation cannot properly be described by a single fractal dimension because they exhibit multifractal characteristics. The obtained results demonstrate that the time series as obtained exhibit multifractality caused by long-range time correlations.Comment: 20 pages, 3 figures, 3 tables; Chaos, Solitons & Fractals (in press

Benefits of Improved Groundnut Technologies to Resource-poor Farmers: A Participatory Approach

Considering that non-adoption of improved groundnut technologies by the small and resource-poor farmers is due to non-availability of quality seeds, poor knowledge, inappropriateness of technologies, etc., in the current study, improved groundnut technologies have been implemented through participatory mode so as to generate awareness about improved technologies among them. The participatory approach could make the farmers to learn, adopt and spread new technologies. The economic indicators have shown that a net return of Rs 7104 per ha was realized by adopting improved varieties and integrated crop management (ICM) package during kharif season, and it is higher than the returns realized by growing local variety (AK-12-24) with local practice (Rs 2010/ha). The cost of production has been found to be Rs 11.04/kg and 13.98/kg among the improved practice and farmers’ practice, respectively. A similar trend of higher net returns (Rs 13820/ha) and lower cost of production (Rs 8.86 per/kg) has been observed with improved practice during the rabi season, compared to the lower net returns (Rs 6309/ha) and higher cost of production (Rs 11.34 per/kg) with farmers’ practice. The informal seed supply system implemented through seed bank operation in a participatory mode has increased the improved groundnut seed availability at the village level. The seed multiplication programme could increase the spread of improved varieties from 32 ha to 69 ha in the adopted villages and from 15.9 ha to 85 ha in the neighbouring villages within a period of three years. It will help increase productivity levels of crops and income of farmers. The informal seed supply system implemented through seed bank operation has been found very successful in the faster technology spread. Hence, this model may be replicated in other areas to provide improved seeds to small and marginal farmers. It will also help in achieving self-sufficiency in improved varietal needs at the village level.Agricultural and Food Policy,

Amplification of localized body forces in channel flows of viscoelastic fluids

The study of nonmodal amplification of distributed body forces in channel flows of viscoelastic fluids has provided useful insights into the mechanisms that may govern the initial stages of transition to elastic turbulence. However, distributed body forces are not easy to implement in experiments and so there is a need to examine amplification of localized body forces. In this work, we use the linearized governing equations to examine such amplification in Poiseuille flow of FENE-CR fluids. We first identify the wall-normal location at which the impulsive excitations experience the largest amplification and then analyze the kinetic energy of the fluctuations and the resulting flow structures. For both a Newtonian fluid at high Reynolds numbers and a viscoelastic fluid at low Reynolds numbers, the largest amplification occurs for disturbances that are located near the channel wall. Our analysis of the energy evolution shows that a localized body force in the spanwise direction has the largest impact and that the streamwise velocity component is most affected. For viscoelastic fluids we observe the development of vortical structures away from the source of impulsive excitation. This feature is less prominent in Newtonian fluids and it may provide a mechanism for triggering the initial stages of transition to elastic turbulence.Comment: 25 pages; 9 figure

南インド、クラニュライ卜相炭酸塩岩の温度-圧力-流体履歴

博士(理学)大阪市立大