A method to interpret the magnetic anomaly due to a dipping dike using the resultant of the horizontal and vertical gradients of the anomaly is suggested. The resultant of both the gradients is a vector quantity and is defined as the “complex gradient.” A few characteristic points defined on the amplitude and phase plots of the complex gradient are used to solve for the parameters of the dike. For a dike uniformly magnetized in the earth’s magnetic field, the amplitude plot is independent of [Formula: see text], the index parameter, which depends upon the strike and dip of the dike and the magnetic inclination of the area. The phase plot of the complex gradient is an antisymmetric curve with an offset value equal to [Formula: see text]. For a dike whose half‐width is greater than its depth of burial, two maxima at equal distances on either side of a minimum value appear on the amplitude plot. For a dike whose half‐width is equal to or less than its depth of burial, the amplitude plot is a bell‐shaped symmetric curve with its maximum appearing directly over the origin. In the case of a thin dike, the amplitude function falls off to half its maximum value at the same point on the abscissa where the phase function reaches, i.e., [Formula: see text]. A combined analysis of the amplitude and phase plots of the complex gradient yields all the parameters of the dike. The method is applicable for the magnetic anomaly in either the total, vertical, or horizontal field. A field example is included to show the applicability of the method.

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Field experiments for the integrated management of early leaf spot (ELS) and late leaf spot (LLS) diseases of groundnut were conducted during 1988 to 1990 rainy seasons. All treatments had significantly lower disease severity of ELS and LLS than unsprayed sole crop. Corresponding to the significantly lower severity of both the diseases in various treatments, monetary returns were also significantly higher than that of unsprayed sole crop. The severity of both diseases was significantly different among treatments, between varieties, and due to their interactions. Almost the same trend was followed for monetary returns. The treatments, application of a mixture of fungicides (carbendazim 0.05% + mancozeb 0.2%) at 40, 55 and 70 d.a.s., groundnut intercropped with pigeonpea + two sprays of fungicides at 55 and 70 d.a.s., and groundnut intercropped with pigeonpea + one spray each of neem leaf extract, fungicides and cell-free culture filtrate of Penicillium islandicum at 40, 55 and 70 d.a.s., respectively were equally effective in controlling ELS and LLS. The latter two treatments, and groundnut intercropped with pigeonpea and sprayed separately with neem leaf extract and P. islandicum inoculum at 55 and 70 d.a.s., gave significantly higher net monetary returns (Rs. 9569-11561/ha) with cost-benefit ratios ranging from 1:2·99 to 1:3.63 for Girnar 1 and 1:2·67 to 1:3·48 for JL 24 cultiver.

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All the varieties, advanced breeding lines, germplasm lines, and wild species used in the experiments differed significantly for their ability to allow invasion and aflatoxin production by an aflatoxigenicAspergillus flavus strain. Infection and colonisation were strongly correlated (r = 0.82), while there was no relation between infection and aflatoxin content or colonisation and aflatoxin content (r = 0.15). The varieties ICGS11 and S 206 supported less infection and colonisation (range 35 to 40%). Lowest aflatoxin content was recorded in Chitra (3,200 ppb), while it was highest in Kaushal (38,250 ppb). A cross derivative of GAUG1 × NC Ac 17133 R F showed lowest infection and colonisation (86,3 and 25,28%, respectively), and also supported moderate aflatoxin production (4,000 ppb). Among germplasm lines spancross supported lowest aflatoxin production (2,026 ppb) while both the wild species vz. ICG 8127 and ICG 8128 were highly susceptible to infection, colonisation, and aflatoxin production.

In conventional interpretation of electrical resistivity data, either one uses an empirical method (Moore, 1945) or an analytical method (Tagg, 1934; Roman, 1934; or Mooney and Wetzel, 1956). While the Tagg, Roman, and Mooney and Wetzel systems are based on theoretical considerations, they are tedious and time‐consuming. The Moore method, while it is very rapid, has the disadvantage of not yielding absolute values of resistivity. Sarma (1963) suggested a modification of the Moore method using Hummel’s (1931) principle, whereby one could obtain absolute values of resistivity. However it is seen that, under certain conditions, Sarma’s method yields resistivity values with a negative sign which cannot be interpreted as having any real physical significance in geological situations.

A study of the magnetic anomalies produced by sloping geologic contacts, thin dikes, and horizontal cylinders has revealed that a single relationship exists among the magnetic anomalies created by them. The magnetic anomaly due to a horizontal cylinder, the first horizontal derivative of the magnetic anomaly due to a thin dike, and the second horizontal derivative of the magnetic anomaly due to a sloping contact are found to be identical in shape. Gay (1963, 1965) presented standard curves to interpret the magnetic anomalies over long tabular bodies (1963) and long horizontal cylinders (1965). It is shown here that the same curves can also be used to interpret the total, vertical and horizontal magnetic anomalies due to sloping geologic contacts.

Effects of sinusoidal magnetic fields on chawki silkworm rearing have been studied. The experiment was conducted using a multi X Bi silkworm hybrid, PM x CSR 2. Disease-free layings were reared from hatching to cocooning and by subjecting first and second instar to three magnetic field frequencies: 0.1, 1.0, and 10 Hz at 1500 nT, pp, for six days at six hours per day. Controls were maintained simultaneously. Larval durations for both young-stage chawki (I and II) and late stage (III, IV, V) were calculated in days and hours, including the feeding and moulting periods for I to IV instars, and the feeding period for V instar up to the time of spinning. The study revealed that the magnetic exposures reduced both feeding and moulting times with no adverse effects on larval growth. The substantial reductions in time, 33 hours in instars I and II, and 64 hours in total larval duration, could be commercially important in chawki rearing, saving time, leaf consumption, and labor expenses.