An Economic Analysis of Tank Rehabilitation in Madurai District of Tamil Nadu

There has been a growing realization for rehabilitation and restoration of irrigation tanks with farmers’ participation. The study has presented the costs and benefits of tank rehabilitation and financial feasibility of investment in tank rehabilitation. The total annual income has been found higher in the rehabilitated tanks than the non-rehabilitated tanks and amongst the rehabilitated tanks, panchayat tanks with community well has depicted the highest annual income. The investment analysis has revealed the net present worth to be positive, the B-C ratio to be more than 1.5 and the internal rate of return to be more than the opportunity cost of capital. This shows that all the three investments in tank rehabilitation are economically viable. The study has suggested that rehabilitation work should be undertaken in all the non-rehabilitated tanks also. Besides, efforts should be made to provide supplemental irrigation to crops and to improve the PWD tank management regime.Agricultural and Food Policy,

Universal aging properties at a disordered critical point

We investigate, analytically near the dimension $d_{uc}=4$ and numerically in $d=3$, the non equilibrium relaxational dynamics of the randomly diluted Ising model at criticality. Using the Exact Renormalization Group Method to one loop, we compute the two times $t,t_w$ correlation function and Fluctuation Dissipation Ratio (FDR) for any Fourier mode of the order parameter, of finite wave vector $q$. In the large time separation limit, the FDR is found to reach a non trivial value $X^{\infty}$ independently of (small) $q$ and coincide with the FDR associated to the the {\it total} magnetization obtained previously. Explicit calculations in real space show that the FDR associated to the {\it local} magnetization converges, in the asymptotic limit, to this same value $X^{\infty}$. Through a Monte Carlo simulation, we compute the autocorrelation function in three dimensions, for different values of the dilution fraction $p$ at $T_c(p)$. Taking properly into account the corrections to scaling, we find, according to the Renormalization Group predictions, that the autocorrelation exponent $\lambda_c$ is independent on $p$. The analysis is complemented by a study of the non equilibrium critical dynamics following a quench from a completely ordered state.Comment: 8 pages, 5 figure

Ferromagnetism in nanoscale BiFeO3

A remarkably high saturation magnetization of ~0.4mu_B/Fe along with room temperature ferromagnetic hysteresis loop has been observed in nanoscale (4-40 nm) multiferroic BiFeO_3 which in bulk form exhibits weak magnetization (~0.02mu_B/Fe) and an antiferromagnetic order. The magnetic hysteresis loops, however, exhibit exchange bias as well as vertical asymmetry which could be because of spin pinning at the boundaries between ferromagnetic and antiferromagnetic domains. Interestingly, like in bulk BiFeO_3, both the calorimetric and dielectric permittivity data in nanoscale BiFeO_3 exhibit characteristic features at the magnetic transition point. These features establish formation of a true ferromagnetic-ferroelectric system with a coupling between the respective order parameters in nanoscale BiFeO_3.Comment: 13 pages including 4 figures; pdf only; submitted to Appl. Phys. Let

Induced spawning in sea urchins

The gonad wall of the sea urchin consists of an outer epithelium, the outer surface of which is bathed in the perivisceral fluid, a middle layer of conspicuous bands of smooth muscles and connective tissue and an inner layer of developing gametes with nutritive cells (Vivek Raja, 1980). The release of gametes, in nature is effected by the contraction of the muscular bands which is directly under the stimulatory effect of the radial nerve hormone (Cochran and Engelmann, 1972). The gamete discharge may be induced by acetylcholine, potassium chloride or by electrical stimulation