Browsing by Author "B.N. Prasad"

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Circadian basis of photoperiodically induced testicular growth in redheaded bunting, Emberiza bruniceps
(1982) P.D. Tewary; B.N. Prasad; V. Kumar
Short day (8L : 16D), pretreated adult male redheaded buntings were held on various light-dark cycles of 20 to 30 h duration, in which a fixed ultra-short photophase of 3 h was combined with scotophases of varying duration. A photoperiodic testicular response was obtained only in 28- and 30-h cycles (3L : 25D and 3L : 27D). The same photo-period (3 h) in 20- to 26-h cycles (3L : 17D, 3L : 19D, 3L : 21D and 3L : 23D) failed to stimulate testicular growth. The results can be interpreted on the assumption that the positive testicular response in this species, under ultra-short-day light cycles, is the result of an advance in the photosensitive phase of the photoperiodic response system so that it coincides at least partly with the external photophase. The results thus appear to conform with the Bünning hypothesis or external coincidence model. © 1982.
Electrometric study of Bismuth Trichloride Complexes with thiourea in organic solvents
(1959) V.D. Anand; B.N. Prasad
Complexes of bismuth with thiourea, phenyl thiourea, p‐toluyl thiourea and urea have been studied electrometrically, employing the Pt/W and Bi/W bimetallic electrode systems. Two complexes of the general type 2 BiCl3 · 3 CS(NH2)2 and BiCl3 · 3 CS(NH2)2 have been observed. A possible structural formula for the stable complex BiCl3 · 2 CS(NH2)2 has been proposed. Copyright © 1959 Verlag GmbH & Co. KGaA, Weinheim
Influence of the applied potential on the Joshi-effect
(1947) B.N. Prasad; T.C. Jain
The distribution of the total current i, as inerial which represents (owing to the low capacity of the aerial) the highest (mean) frequency; as iHF and iLF, the filtered high and low frequency parts of the tube current in the LT line has been studied in dark and in light at applied potentials varied in the range 5-9 kV, using a vacuo-junction and double diode as detectors. The relative Joshi-effect %Δi, i.e., the percentage photo-diminution of the current in dark in a given frequency region varies as iaeriai >iHF >iLT >iLF, which is also the order in respect of their mean frequencies. The 'threshold potential' Vm is found to be independent of the nature of both the detectors and also of the frequency regions; for each of these, % Δi is maximum near Vm. The decrease on increasing the applied potential, in % Δi is attributed to the corresponding preponderance of iLF which is comparatively insensitive to the production of this phenomenon. © 1947 Indian Academy of Sciences.
Production of the Joshi effect in mercury vapour [18]
(1949) B.N. Prasad
[No abstract available]
The photo‐gonadal response of a migratory bunting: Evidence of an external coincidence system
(1982) B.N. Prasad; Vinod Kumar; P.D. Tewary Reader
Male redheaded buntings (Emberiza bruniceps) were subjected to continuous darkness (DD) or short days (8L/16D) after photo‐stimulation (15L/9D) for either 15 or 30 days. Two groups of birds (four each), after photo‐stimulation for 30 days, were continued on a regimen of 15L/9D. Another two groups (of four each) of photo‐sensitive birds were also subjected to DD or 8L/16D; they served as controls. The effect of transfer to DD or 8L/16D on the size of testes was found not be dependent upon the size attained at the time of transfer. The rate of testicular regression was nearly the same under both the treatments, i.e., in those birds transferred either to DD or to 8L/16D. The birds that were maintained on 15L/9D maintained enlarged testes; this excluded the possibility of the onset of photo‐refractoriness during the treatment period. On the other hand, testes were not photo‐stimulated in the photo‐sensitive birds subjected to DD or 8L/16D. These results are consistent with the Bünning‐Pittendrigh avian external coincidence model, but could be explained alternatively by a relatively simple internal coincidence model. Nevertheless, the application of the law of parsimony suggests the acceptance of the hypothesis of the external coincidence model. Copyright © 1982 Wiley‐Liss, Inc., A Wiley Company