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,

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

Thin layer chromatographic separation of lipids in ovary, testis and gut of the sea urchin Salmacis virgulata

Sea urchins accumulate large amounts of lipid in ovary during its reproductive cycle (Giese, 1966 ; Vivek Raja, 1980); Lipids deposited in the developing gonads may be synthesized within the oocytes or transported from the gut. A variety of lipid classes are also found to occur in the ovary, testis, gut, body wall and coelomocytes of the sea urchins (Allen, 1974; Vivek Raja, 1980). The present experiment is designed to separate and identify the different lipid classes present in gut, testis and ovary of the sea urchin Salmacis virgulata employing thin layer chromatographic metho

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

Determination of reproductive activity in sea urchins

The most widely used quantitative method for assessing the reproductive activity is the gonad index (Giese and Pearse, 1974). But, in species such as sea urchins possessing considerable quantities of nutritive tissues in the gonad, both an increase and a decrease in gonad index may be a consequence of changes. in the number of nutritive cells without a corresponding change in gametogenic cell