Showing papers by "Banaras Hindu University published in 1972"

Evolution of karyotypes in snakes.

Abstract: Karyotype analysis and morphometric measurement of the chromosomes of 17 species of snakes have been done. Chromosomes of different species so far worked out in each family have been compared using quantitative methods to derive chromosomal affinities between species of different taxonomic categories. The following conclusions have been drawn: (i) It is suggested that the retention of Xenopeltidae as a separate family is unnecessary and the only species Xenopeltis unicolor referred to in that group should be included in the family Boidae. (ii) The subfamilies, Boinae and Pythoninae cannot be distinguished chromosomally. (iii) On the basis of chromosomal similarities, the cytologically known species of Colubridae. have been put into 13 different groupings which do not always correspond to the views of the present day colubrid taxonomists. (iv) In Hydrophiidae, speciation seems to have occurred through changes in the 4th pair of autosomes and sex chromosomes in general and the W chromosome in particular. Evidences are presented to show that fission and inversion have played an important role in bringing about the structural rearrangements in this group. (v) Family Viperidae according to taxonomists is divided into two subfamilies. Both the subfamilies are chromosomally very similar.

The lack of evidence for coadaptation in geographic populations of Drosophila ananassae

Abstract: Crosses were made between geographic races of Drosophila ananassas from different localities in India. All these strains employed in the present experiments were polymorphic for the gene arrangements in the second chromosome due to the occurrence of alpha (subterminal) inversion. After ten generations it was observed that the heterozygotes were the most superior genotype and their frequencies remained above fifty percent in all these strains which served as controls and in the hybrid populations of mixed geographic origin. Thus it was found that interracial hybridization does not lead to breakdown of heterosis. The chief conclusion from these experiments is that evidence for coadaptation is lacking in D. ananassae. This finding apparently conflicts with what has been claimed for other species.

Crystal Dynamics of Magnesium Oxide

Abstract: The crystal dynamics of magnesium oxide have been studied by incorporating the effect of three-body interactions in the framework of the shell model on the lines of the work of Singh and Verma [Phys. Rev. B 2, 4288 (1970)]. The theoretical dispersion curves in the three symmetry directions and specific-heat variation with temperature have been calculated and compared with the corresponding experimental results. The experimentally observed second-order infrared absorption and the Raman spectra have also been interpreted by using the critical-point analysis and the combined-density-of-states approach. An excellent agreement has been obtained with the recently measured neutron-scattering, specific-heat, and second-order infrared-absorption and Raman-scattering data.

["Thyroidectomy cells" and "castration cells" in the Japanese quail, Coturnix coturnix japonica. Ultrastructure and cytoenzymology].

Abstract: On compare l'ultrastructure et la localisation des phosphatases acides au niveau des cellules hypophysaires delta et beta, chez des Cailles mâles thyroidectomisees et maintenues en photoperiode courte ou bien castrees, puis placees en photoperiode longue. On etudie en outre, dans ces deux cas, les effets d'injections de doses croissantes de thyroxine.

On the existence and structure of gadolinium and samarium monoxides and their related lower oxides

Abstract: The monoxides of the rare earth metals are currently receiving attention because of the possibility of their being ‘n’ or ‘p’ type semiconductors [6]. Unlike the R2O3 type sesquioxides whose structures and existence have been well established, very little details regarding the existence, structure, and defect substructure of monoxides are available. The present investigation describes the existence and structural crystallography and defect substructure of gadolinium and samarium monoxides and of their reduced variants. The gadolinium and samarium monoxides were prepared in the form of thin film and were found to have zinc blende type structures with lattice parameters equal to (5.24 ± 0.05) A and (5.15 ± 0.05) A respectively. Annealing of the original material has been found to result in the formation of superlattices and the accompanying domain substructures. The superlattices as described on hexagonal axes have rhombohedral unit cells with lattice parameters and (ac being the lattice parameter of the fundamental zinc sulphide type unit cell). The detailed structure analysis of the superlattices has been carried out and it has been found that the superlattices are formed by the ordered arrangement of oxygen vacancies in the parent lattices, the nonstoichiometric variants are of the form ROx where R = Gd, Sm and x = 0.656. Den Monoxiden der Seltenen Erden wird wegen der Moglichkeit, „n”- oder „p”-leitende Halbleiter zu bilden, laufend starkere Beachtung geschenkt [6]. Im Gegensatz zu den R2O3-Sesquioxiden, deren Struktur und Existenz gut bekannt ist, sind nur wenige detaillierte Angaben uber die Existenz, Struktur und Defektsubstruktur der Monoxide erhaltlich. Die vorgelegte Untersuchung beschreibt die Existenz und strukturelle Kristallographie und Defektsubstruktur von Gadolinium- und Samariummonoxid und deren reduzierte Varianten. Die Gadolinium- und Samariummonoxide wurden in Form dunner Schichten erhalten. Es wurde gefunden, das sie Zinkblendestruktur besitzen mit Gitterparametern von (5,24 ± 0,05) bzw. (5,15 ± 0,05) A. Temperung von ursprunglichem Material ergab die Bildung von Ubergittern und der begleitenden Domanen-Substrukturen. Die Ubergitter, durch hexagonale Achsen beschrieben, haben rhomboedrische Einheitszellen mit den Gitterparametern und (ac ist der Gitterparameter der fundamentalen Einheitszelle vom Zinksulfidtyp). Es wurde eine genaue Strukturanalyse der Ubergitter durchgefuhrt und gefunden, das die Ubergitter durch die geordnete Anordnung von Sauerstofflucken im Gitter gebildet werden, wobei die nichtstochiometrischen Varianten von der Form ROx sind, mit R = Gd, Sm und x = 0,656.

Variable electronegativity SCF-MO calculations on the electronic structure and spectra of some substituted benzenes I. Monosubstitutions

Abstract: π-electron SCF-MO theory in its variable electronegativity formalism has been applied to some monosubstituted benzenes. Calculated charge densities and bond orders for the ground and the first excited electronic states are correlated with chemical reactivity and the changes in molecular geometry on electronic excitation. The calculated results for spectra are compared with those obtained using the PPP method and also with the available experimental data.

Calculation of the vertical gradient of the gravity field using the fourier transform

Abstract: Fourier transform techniques have been used to calculate the theoretical filter (amplitude) response function of Nth order vertical derivative continuation operation. The amplitude response functions of the vertical gradient and its continuation follow from the same. These response functions are subsequently used to calculate the weighting coefficients suitable for two dimensional equispaced data. A shortening operator has been incorporated to limit the extent of the operator. For comparative study, some of the developed coefficient sets and the one presented in this paper are analysed in the frequency domain and their merits and demerits are discussed.

Decomposition of the metastable phase in the silver-germanium system

Abstract: The decomposition behaviour of the metastable h.c.p. phase in a splatcooled silver-23 at. % germanium alloy was studied by differential thermal analysis, X-ray and electron metallographic techniques. A two-stage decomposition process was observed. The activation energies for the two stages were found to be 0·91±0·09 eV/atom and 1·95±0·19 eV/atom, respectively. The first stage is associated with the transformation from h.c.p. to metastable f.c.c. solid solution, the second stage represents the precipitation of germanium from this solid solution. The total enthalpy of transformation was found to be 2·21±0·22 meV/atom.

The Dynamical Behaviour of Silver Chloride with Modified Shell Model

Abstract: A detailed study is presented of the dynamical behaviour of silver chloride using the modified shell model, developed by Verma and Singh, which accounts for the deformation of electron shells introducing three-body interactions. The results obtained are in fair agreement with the experiments on phonon dispersion. Debye temperatures, second-order Raman scattering, and infrared absorption spectra of the solid under consideration. Es wird eine ausfuhrliche Untersuchung des dynamischen Verhaltens von Silberchlorid mit dem modifizierten Schalenmodell von Verma und Singh, das die Deformation der Elektronenschalen durch Einfuhrung von Drei-Ko-per-Wechselwirkungen berucksichtigt, angegeben. Die erzielten Ergebnisse sind in befriedigender Ubereinstimmung mit Experimenten uber die Phononendispersion, Debyetemperaturen, Raman-Streuung 2. Ordnung und Infrarot-Absorptionsspektren der betrachteten Festkorper.

The pituitary gland of the musk shrew. Suncus murinus L. (Insectivora), with special reference to the cytology of the adenohypophysis.

Abstract: The pituitary gland of the musk shrew, Suncus murinus L. was studied with special reference to the cytology of the adenohypophysis. In addition to the agranular cells (chromophobes), seven morphologically and tinctorially distinct chromophilic cell types (four mucoid and three acidophilic) were observed in the pars anterior. These cells have been tentatively named as types one to seven. On the basis of their morphology, topography and staining reactions, cells of types one to six were compared, respectively, with the TSH, FSH, ICSH (LH), LTH (prolactin), STH and ACTH cells of other mammals. The identity of type 7 cells could not be determined. Although mucoid cells (types 1, 2) are more concentrated in the rostroventral region of the pars anterior, a definite “zona tuberalis” seems to be lacking. Since the musk shrew is not a seasonal breeder, the gonadotropic cells (types 2, 3) of the adenohypophysis do not seem to fluctuate in structure during the different times of the year. However, conspicuous hypertrophy, hyperplasia and intense secretory activity of type 4 cells during pregnancy and lactation reinforces the postulation that these cells are lactotropic in function. Follicular cysts and colloid in the residual cleft were observed in a few instances. Their possible origin and significance are discussed.

A new leaf spot of maize incited byCurvularia clavata

Abstract: In September 1969 a leaf spot of maize ‘Composite Jawahar’, incited byC. lavata Jain, was observed at the College Farm of the Banaras Hindu University, Varanasi. The fungus seriously damages maize leaves and considerably reduces its fodder value. The symptoms of the disease and taxonomic characters of the pathogen are being described in detail.

Bremsstrählung as a Possible Source of UHF Emissions from Lightning

Abstract: FEW ultra high frequency (UHF) studies from lightning discharges have been made. Takagi and Takeuti1 reported measurements at 500 MHz; these were later extended by Brook and Kitagawa2 who, with the help of a ‘Polard type R’ microwave receiver, scanned the frequency range of 400 MHz to 1 GHz. They showed that most high frequency radiation was associated with the stepped and dart leaders and with the k-changes. By contrast, the return stroke radiated poorly. Kosarev et al.3,4 have reported measurements in the range 100 MHz to 1.3 GHz which indicated that at a distance of 1 km from the foot of the channel, the power received was independent of frequency and was in the order of 10−15 W/m2/Hz. Kosarev et al.4 suspected that the electron synchrotron process might be responsible for the observed high frequency emissions. Considering the highest channel temperatures so far measured (of the order of 104 K), it does not seem possible to associate relativistic velocities to the electrons present in the channel and the possibility of synchrotron radiation from lightning seems remote.

Disturbance-Variance Estimation in Simultaneous Equations When Disturbances are Small

Abstract: Employing the small-disturbance approach, I study the bias and mean squared error of a class of estimators of the variance of the disturbances in a simultaneous linear stochastic equation model. The estimator considered is the residual sum of squares after estimation of the structural parameters by a k-class estimator, divided by an arbitrary scalar. The scalar which minimizes the mean squared error is (T—n+2), regardless of which k-class estimator is used, where T is the number of observations and n is the number of structural parameters estimated. Using the scalar (T—n+2), the member of the k-class that minimizes the mean squared error is classical least squares.

MultipleW chromosome in a sea snake,Enhydrina schistosa daudin

Abstract: Un serpent marin (Enhydrina chistosa Daudin, Hydrophiidae) a 32 chromosomes chez le Ф, 33 chez la М, cette derniere ayant unW-chromosome supplementaire. La digametie serait: Ф-ZZ; МZ W1W2.