Showing papers by "Banaras Hindu University published in 1969"
TL;DR: In this paper, a new lattice dynamical model of ionic solids has been suggested which is obtained by injecting the three-body coupling coefficients into the shell model of Woods et al. in a way that preserves symmetry in the wave vector space.
Abstract: The so-called S2-approximation in the Heitler-London theory of ionic crystals as developed by Lowdin gives rise to a three-body contribution in the cohesive energy. The present paper describes a method of deriving the coupling coefficients for the three-body potential from expressions given by Lundqvist. These coupling coefficients involve certain lattice sums which can be evaluated in terms of incomplete gamma functions by a method due to Born and Bradburn. A new lattice dynamical model of ionic solids has been suggested which is obtained by injecting the three-body coupling coefficients into the shell model of Woods et al. in a way that preserves symmetry in the wave vector space. Preliminary calculations show that this model can prove superior to other current models.
Die sogenannte S2-Naherung in der Theorie von Heitler-London der Ionenkristalle, wie sie von Lowdin entwickelt wurde, gibt Anlas zu einem Dreikorperbeitrag in der Anziehungsenergie. Die vorliegende Arbeit beschreibt eine Methode zur Ableitung der Kopplungskoeffizienten fur das Dreikorperpotential aus den Ausdrucken, die von Lundqvist gegeben wurden. Diese Kopplungskoeffizienten schliesen gewisse Gittersummen ein, die mit unvollstandigen Γ-Funktionen nach der Methode von Born und Bradburn berechnet werden konnen. Eine neues gitterdynamisches Modell der Ionenfestkorper wird vorgeschlagen, das durch das Einbeziehen der Dreikorperkopplungskoeffizienten in das Schalenmodell von Woods et al. in einer Weise erhalten wird, die die Symmetrie im Raum der Wellenvektoren erhalt. Vorlaufige Berechnungen zeigen, das dieses Modell sich anderen gelaufigen Modellen als uberlegen erweisen kann.
137 citations
TL;DR: It is suggested that changes in thyroid activity influence the output of the gonad-stimulating hormones from the adenohypophysis, which in turn regulate the annual and body weight cycles of Lal and Spotted Munia.
66 citations
TL;DR: The unequivocal identification of W chromosome in the females of five species of the present investigation further strengthens the generalisation that, at least in Carinatae, the sex chromosome constitutions are of ZZ and ZW types in males and females respectively.
Abstract: Karyotype analysis and morphometric measurement of the chromosomes of eleven species of Indian birds are described. The unequivocal identification of W chromosome in the females of five species of the present investigation further strengthens the generalisation that, at least in Carinatae, the sex chromosome constitutions are of ZZ and ZW types in males and females respectively. — The chromosomes of different species of birds so far worked out in each order have been compared using quantitative methods and tentative conclusions have been drawn regarding chromosomal affinities between species of different taxonomic categories.
48 citations
TL;DR: In this paper, a modified shell model has been used to compute the dispersion curves and the two phonon combined density of states (C.D.S.) curves of KBr and KI.
Abstract: The three-body coupling coefficients computed in an earlier paper [14] have been injected in the shell model of ionic solids treating both the ions as polarizable. This modified shell model has been used to compute the dispersion curves and the two phonon combined density of states (C.D.S.) curves of KBr and KI. Excellent agreements have been obtained with the results of neutron scattering and Raman scattering experiments.
Die Dreikorper-Kopplungskonstanten, die in einer fruheren Arbeit [14] berechnet worden waren, wurden als Ausgangsdaten fur Rechnungen im Schalenmodell fur heteropolare Festkorper benutzt, wobei beide Ionenarten als polarisierbar behandelt wurden. Dieses modifizierte Schalenmodell wurde benutzt, um die Dispersionskurven und die Kurven der kombinierten Zwei-Phononenzustandsdichte (C.D.S.) von KBr und KJ zu berechnen. Es wurde sehr gute Ubereinstimmung mit den Ergebnissen von Neutronenstreuungs- und Ramanstreuungsexperimenten erhalten.
40 citations
TL;DR: This is the first report of a mutation induced by ultraviolet irradiation leading to true branching in the typically unbranched genus Nostoc of the order Nostocales, although algae of the family Scytonemataceae of the latter order show false branching.
Abstract: SEVERAL authors1–3 have induced mutations in blue–green algae by ultraviolet irradiation, but the mutation reported here seems particularly significant because it obscures the criteria for delimitation of taxa in the Cyanophyceae4. True branching is a distinctive feature of the algae comprising the order Stigonematales4 and is absent in Nostocales, although algae of the family Scytonemataceae of the latter order show false branching. This is the first report of a mutation induced by ultraviolet irradiation leading to true branching in the typically unbranched genus Nostoc of the order Nostocales.
37 citations
TL;DR: In this article, the preparation of morpholine complexes of nickel(II), copper(II) and zinc(II)-sulphates is described, and possible structures for these complexes in the solid state are discussed.
36 citations
TL;DR: It appears that increased thyroid activity, in response to gonadal and adrenal steroids is independent of pituitary mediation.
30 citations
TL;DR: It is suggested that Robertsonian type of mechanism (centric fusion or fission) has played a major role in the karyotype evolution in the genus Pipistrellus.
Abstract: SUMMARYChromosome numbers have been determined from the bone marrow cells of the five vespertilionid bats. In three species of the genus Pipistrellus the diploid numbers are 2 n=34, 36 and 38. In two species of the genus Scotophilus the diploid number is 2 n=36. It is suggested that Robertsonian type of mechanism (centric fusion or fission) has played a major role in the karyotype evolution in the genus Pipistrellus.
25 citations
TL;DR: It is suggested that the existence of two distinct groups of portal vessels is correlated with the cytological differentiation of the pars distalis and may be widespread among birds.
19 citations
TL;DR: A series of hydrochloride salts of 5-diethylamino- acetamido-2-arylimino-3-aryl-4-thiazolidones synthesized as potential local anesthetic agents showed potent local anesthetics.
18 citations
TL;DR: Der Plasma- and the Urin-Askorbinsäurespiegel wurden während der postoperativen Periode nach täglicher Zufuhr von 500 mg Vitamin C bei Patienten kolorimetrisch gemessen gemessen.
Abstract: Der Plasma- und der Urin-Askorbinsaurespiegel wurden wahrend der postoperativen Periode nach taglicher Zufuhr von 500 mg Vitamin C bei Patienten kolorimetrisch gemessen. Der schnelle Verbrauch des Vitamins macht einen Askorbinsaurebedarf zur Kollagensynthese am Ort der Wunde wahrscheinlich.
TL;DR: The available evidence indicates that the neuroendocrine cause of the male-induced pregnancy failure in mice is the failure of prolactin secretion by the adenohypophysis with consequent failure of corpus luteum development and the return of the newly mated female to estrus as though mating has not occurred.
TL;DR: In this article, single crystals of CdS were grown from the vapour phase under varied conditions to detect the presence of growth faults and polytypic structures analogous to those exhibited by ZnS.
TL;DR: In this article, the lattice parameters of cadmium oxide at elevated temperatures were measured with a Unicam 19 cm dia. powder camera and the results of the measurements were expressed in the parabolic equation, a t = 4.6937 + 62.
TL;DR: A demonstrable increase of stainable neurosecretory material was noticed all along the hypothalamo-neurohypophysial complex of some specimens subjected to complete darkness, suggesting possible sites of release of neurohormones along the highly vascular hypothalamic region.
Abstract: The complicated architectural pattern of the preoptico-neurohypophysial neurosecretory system of Clarias batrachus is described using bulk staining procedure. The nucleus preopticus is U-shaped; its limbs constitute the PMC and PPC. The difference in staining intensities noticed among the PMC and PPC might suggest a possible functional difference within the system. Axons of the PMC diagonally pass through the PPC and emerge along with those of the latter to form the right and the left main tracts. The folds and recurrent curves of the neurosecretory axonal tracts, the formation of several pairs of lateral tracts and their union to form median tracts might be devices to increase the storing and releasing capacity for the neurosecretory material. The presence of prominent Herring bodies, and diffuse areas in the neurosecretory tract suggest possible sites of release of neurohormones along the highly vascular hypothalamic region. The common neurosecretory tract is divided into several smaller branches at the level of the pars distalis prior to entering the pars intermedia. Branches do penetrate into the pars distalis, but those entering the rostral component of the pituitary are relatively scarce. Regeneration of the anterior stump of the severed hypophysial stalk to form a neurohypophysis-like organ is also demonstrated in toto with the aid of the bulk staining procedure. A demonstrable increase of stainable neurosecretory material was noticed all along the hypothalamo-neurohypophysial complex of some specimens subjected to complete darkness. Total staining methods could be advantageously used to map the course of recurrent tracts and extra-hypophysial axonal endings. Since the neurosecretory system seems to exhibit a varied structural pattern in different fishes, extension of this study to a larger number of species may throw additional light on the function and the evolution of this important system.
TL;DR: In this paper, it is suggested that the grain growth in this case is assisted by thermal stresses which are set up as a result of local heating, and are thus different from those resulting from direct annealing treatment.
TL;DR: Two mutant strains of Phormidium mucicola were isolated which are stable and inheritable after exposures to UV and one is a photoheterotrophic mutant requiring addition of an organic growth factor to the basal medium which appears fulfilled by either casein hydrolysate, glucose, acetate or vitamin mixture.
Abstract: After exposures to UV, two mutant strains of Phormidium mucicola were isolated which are stable and inheritable:
TL;DR: The binding energies of the b.c. and c.h. phases of sodium have been computed using Hellmann-type and modified Coulomb pseudopotentials as mentioned in this paper, and the computed values give a fair agreement with the experimental results wherever available.
Abstract: The binding energies of the b.c.c. and c.p.h. phases of sodium have been computed using Hellmann-type and modified Coulomb pseudopotentials. The binding energy of the c.p.h. structure is found to be about 2% more at 5°K than that of the b.c.c. structure as calculated from these pseudopotentials. The compressibility of the b.c.c. phase has also been calculated. The computed values give a fair agreement with the experimental results wherever available.
Die Bindungsenergien der kubisch-raumzentrierten und hexagonal-dichtgepackten Phasen von Natrium wurden mit modifizierten Coulomb-Pseudopotentialen und Pseudopotentialen vom Hellmann-Typ berechnet. Die Bindungsenergien sind fur die hexagonaldichtgepackte Struktur bei 5°K etwa 2% groser als die der kubisch-raumzentrierten Struktur, wie aus diesen Pseudopotentialen berechnet wurde. Die Kompressibilitat der kubischraumzentrierten Phase wurde ebenfalls berechnet. Die berechneten Werte geben zufrieden stellende Ubereinstimmung mit den zuganglichen experimentellen Ergebnissen.
TL;DR: Evidence concerning the time of crossing over indicates that chiasma formation and genetic recombination do not occur during premeiotic DNA synthesis, which has been presumed primarily to affect DNA synthesis.
Abstract: WHENEVER it has been possible to test unambiguously the relationship between chiasmata and crossing over, they have been found to coincide in time and place. Evidence concerning the time of crossing over indicates that chiasma formation and genetic recombination do not occur during premeiotic DNA synthesis. Various physical and chemical agents affect recombination and chiasma formation and treatment is effective during the S phase (DNA synthesis) before leptotene and during the meiotic DNA synthesis at zygotene–pachytene. Treatment with mitomycin C and γ-rays during the S phase before leptotene has always caused a decline in chiasma frequency or recombination except in Chlamydomonas1. An increase of chiasma frequency or recombination has been found as a rule after treatment with deoxyadenosine at zygotene, again except with Chlamydomonas, when there was a decline in recombination. All these agents have been presumed primarily to affect DNA synthesis. The presence of cycloheximide at zygotene–pachytene prevents the formation of chiasmata2, which also happens when Trillium meiocytes are explantcd into culture at leptotene.
TL;DR: In this article, the authors considered possible deviations in the regular ABACA sequence of stacking (0004) close-packed planes in the double hexagonal close packed (d.h.c.p.) structure.
TL;DR: It is suggested that while day-length may induce gonadal development, in nature, some other environmental factor is responsible for bringing about annual gonadal regression.
Abstract: When black-headed Munia, Munia malacca malacca, were subjected to different photoperiods, testes started developing practically immediately under constant short (8 or 9 hrs.) days, but after a delay of three months under long (15-hr.) photoperiod. Under both the photoperiods, gonads were maintained permanently in a full breeding condition. Under natural photoperiod, tests began to grow six months later than those of short-day brids and attained their maximal size four months after their recrudescence. However, thereafter they showed a rapid regression in size.It is suggested that while day-length may induce gonadal development, in nature, some other environmental factor (s) is responsible for bringing about annual gonadal regression.
TL;DR: Observations on morphology, sterility and cytology of some interchangetrisomics obtained from the progeny of radiation induced interchangeheterozygotes in a 6-rowed barley are described.
Abstract: Observations on morphology, sterility and cytology of some interchangetrisomics obtained from the progeny of radiation induced interchangeheterozygotes in a 6-rowed barley (Hordeum vulgare L.) var. K12 are described. The different interchange trisomics show distinct phenotypic expression and have been classified as “bushy”, “slender”, “robust”, “semi-erect” and “pseudonormal” on the basis of their gross morphology, leaf characteristics, awn and spike lengths. All interchange trisomics show pollen and ovule sterility which varies between plants. Meiotic behaviour is described. The five different interchange trisomics appear to have different extra chromosomes.
TL;DR: In this paper, the equations for determining one- electron energy levels in a generalized diatomic lattice of rectangular potential barriers are given, which has been obtained by the method of the transfer matrix.
TL;DR: In Knochenmarkzellen wurden die Chromosomen eines männlichen Pangolins (Manis pentadactyla L.) untersucht, der Ansicht, dass man die Pangoline in eine besondere Ordnung der Pholidota einreiht.
Abstract: In Knochenmarkzellen wurden die Chromosomen eines mannlichen Pangolins (Manis pentadactyla L.) untersucht. Die Zahl der diploiden Chromosomen betragt 36. Dieser zytologische Befund unterstutzt die Ansicht, dass man die Pangoline in eine besondere Ordnung der Pholidota einreiht.
TL;DR: It is suggested that the 6-week-old rat is more efficient in eliminating its ammonia as urea than the old rat, which may be of significance in the ageing process of the rat.