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Showing papers by "University of Madras published in 1974"


Journal ArticleDOI
TL;DR: The cytological characteristics of the major cell classes and the occurrence of the miniatures of some of these major cell types support the concept of Jones that these cell types might have different cell lineages and might not be capable of transforming into one another.
Abstract: Some of the cytological characteristics of the hemocytes of the scorpion, Palamnaeus swammerdami, were studied. The morphological features of the arachnid hemocytes were observed to be similar to those of hemocytes of insects, millipedes and isopods. Jones' system of hemocyte classification was extended to the arachnid hemocytes. The six classes of hemocytes indentified in the scorpion correspond to prohemocytes, plasmatocytes, granular hemoocytes, cystocytes, spherule cells and adipohemocytes of insects. A cell type comparable to oenocytoids of insects and crustaceans is absent. The prohemocytes can be subdivided into four categories that probably represent the precursors of the major cell types. The cytological characteristics of the major cell classes and the occurrence of the miniatures of some of these major cell types support the concept of Jones (62) that these cell types might have different cell lineages and might not be capable of transforming into one another. Some of the prohemocytes, plasmatocytes and granular hemocytes were amoeboid. The nature of the granules and the vacuoles of plasmatocytes and granular hemocytes were compared with the granules and vacuoles of corresponding hemocytes of other arthropods. Cystocytes did not bring about any visible coagulation similar to their counterparts in millipedes and crustaceans. Plasmatocytes, granular hemocytes and spherule cells were observed to occur in conglomerates. The cell types noted in the present study were compared with the hemocytes of other arachnids.

29 citations


Journal ArticleDOI
TL;DR: Oxygen-consumption values in water under different ambient partial pressures of oxygen indicate that all three species display equally efficient aquatic respiration despite variation in gill area and number, and the R-T response in the different species is no coherent.
Abstract: The gill-surface area and R-T (metabolic rate-temperature) response during aquatic and aerial respiration of three different species of crabs, the subtidal Scylla serrata, the intertidal Sesarma quadratum, and the supratidal Ocypoda platytarsis, were compared. Scylla serrata has the highest, Sesarma quadratum the second highest, and O.platytarsis the lowest gill-surface area. Oxygen-consumption values in water under different ambient partial pressures of oxygen indicate that all three species display equally efficient aquatic respiration despite variation in gill area and number. There is no coherent R-T response either inter- or intra-specifically. However, the ability to extract oxygen from the surrounding medium (respiratory efficiency) conditions the R-T response in the different species. The R-T trends in aquatic respiration of Scylla serrata and aerial respiration of O.platytarsis reveal a normal response to temperature. The proportion of aquaticoxygen uptake to total respiration in all sizes in both Scylla serrata and Sesarma quadratum remains more or less constant (between 88 and 92%), whereas in the supratidal O.platytarsis, this proportion decreases with increasing weight (from 88 to 64 %), indicating a progressive loss of gill respiration to total respiration. All three species are metabolically equally efficient; what one lacks in respiratory surface it compensates by respiratory efficiency.

27 citations


Journal ArticleDOI
TL;DR: In this article, the p-modular absolutely irreducible representations of the finite Chevalley groups have been constructed by Brauer and Nesbitt as early as 1941.

27 citations



Journal ArticleDOI
TL;DR: The morphological features of the hemocytes of the crustacean Ligia exotica are similar to hemocyte of insects and millipedes and it is suggested that the nomenclature based on morphological characters is more suited for crustACEan hemocytes than a nomenClaturebased on behavioural and physiological characters.
Abstract: The morphological features of the hemocytes of the crustacean Ligia exotica are similar to hemocytes of insects and millipedes. Jones system of hemocyte classification is extended to crustacean hemocytes. As in insects, seven classes of hemocytes, identified as prohemocytes, plasmatocytes, granular hemocytes, cystocytes, oenocytoids, spherule cells and adipohemocytes, occur. The prohemocytes can be subdivided into five categories that probably represent the precursor of major cell types. The structural and chemical features of other major cell classes are distinct and support the concept of Jones ('62) that these types might have different lineages and might not be capable of transforming into one another. Some of the prohemocytes, plasmatocytes and granular hemocytes are amoeboid. Cystocytes do not bring about any visible plasma coagulation similar to their counterpart in millipedes. Oneocytoids and adipohemocytes are rare. Plasmatocytes, cystocytes and oenocytoids occur in conglomerates, the significance of which is discussed. The cell types are compared with those of the hemocytes of other crustaceans. It is suggested that the nomenclature based on morphological characters is more suited for crustacean hemocytes than a nomenclature based on behavioural and physiological characters.

21 citations


Journal ArticleDOI
TL;DR: Untersucht wurde die Beschaffenheit der für das Funktionieren des Beutefang- and Geräuscherzeugungs-Mechanismus zuständigen Oberhaut am Tibia-Tarsus-Übergang der Zangen der SkorpionartPalamnaeus swammerdami.
Abstract: Untersucht wurde die Beschaffenheit der fur das Funktionieren des Beutefang- und Gerauscherzeugungs-Mechanismus zustandigen Oberhaut am Tibia-Tarsus-Ubergang der Zangen der SkorpionartPalamnaeus swammerdami. Im UV-Licht zeigt diese Oberhaut Autofluoreszenz. In Hydrolysaten wurden Dityrosin und Trityrosin nachgewiesen, was die Vermutung nahelegt, dass Resilin vorhanden ist.

20 citations


Journal ArticleDOI
TL;DR: The chemical composition of the cuticle in regions which are permeable and impermeable to water in 4 crustaceans was investigated, with special reference to the protein components.
Abstract: The chemical composition of the cuticle in regions which are permeable and impermeable to water in 4 crustaceans (Ocypode platytarsis, Metapenaeus monoceros, Emerita asiatica, Ligia exotica) was investigated, with special reference to the protein components. It was found that the cuticle which is permeable lacks the outer epicuticle or the entire epicuticle compared to the cuticle in the impermeable regions. The permeable cuticle is distinguished by the absence of a fuchsinophil protein, which is a precursor of tanning. Permeability of the cuticle is also associated with the presence of a simple protein, positive to the biuret test, and with a protein containing sulphydryl groups. It is considered that the cuticle protein may play a role in conferring permeability properties to the cuticle itself.

17 citations


Journal ArticleDOI
TL;DR: In this paper, the authors derived expressions for the resultant polarizations of 12 B nuclei obtained in the experimental arrangement of Louvain-Saclay collaboration and investigated how these polarizations are related to the average polarization, the longitudinal polarization and the nuclear recoil asymmetry.

11 citations



Journal ArticleDOI
01 Nov 1974
TL;DR: Two new species, Pyricularia vandalurensis and Spadicoides aggregata are described and four other species, including Circinotrichum fertile Pirozynski and Hodges, Endophragmia alternata Tubaki and Saito are reported for the first time from India.
Abstract: This paper presents descriptions of six hyphomycetes from litter. Two new species,Pyricularia vandalurensis andSpadicoides aggregata are described. Four other species,viz., Circinotrichum fertile Pirozynski and Hodges,Endophragmia alternata Tubaki and Saito,E. atra (Berk. & Br.) M. B. Ellis andPericonia sacchari Johnston are reported for the first time from India.

9 citations


Journal ArticleDOI
TL;DR: In this article, the stability constants of ternary uranyl ion complexes involving dicarboxylic acids were determined by pH metric titrations at a temperature of 31 ± 0·1°C and an ionic strength, μ = 0· 1 M (NaClO4).



Journal ArticleDOI
TL;DR: It is suggested that hardening of the cephalic and thoracic cuticles in C. olivaceous constitutes a protection during those periods when these parts are exposed to the environment.
Abstract: The structure and composition of the cephalic and thoracic cuticles of Clibanarius olivaceous Henderson are described. The cephalic cuticle is completely hardened due to tanning of the epicuticle and the outer part of the procuticle (pigmented Layer). The thoracic cuticle is partially hardened. The differences in extent of tanning reflect the chemical composition of the respective regions. The epicuticle of the cephalic region contains a protein rich in tyrosine, which combines with a sterol to form a lipoprotein complex. This in turn forms the precursor to sclerotin. Phenolic substances appear to be oxidized to quinones by the action of phenolase. The outer part of the procuticle of the cephalic region also contains phenolic substances, but this layer remains only partially tanned. This partial hardening is due to the presence of an inhibitory substance having the nature of ascorbic acid. In the epicuticle of the thoracic region, however, an arrest in tanning appears to be due not to the presence of an inhibitory substance, but to the absence of phenolase necessary for the oxidation of tanning material. In C. olivaceous, the tanning process is much abbreviated. The primary cause of hardening is calcification. The sulphydryl groups and acid mucopolysaccharide detected in the cephalic and thoracic cuticles of C. olivaceous are involved in calcification. It is suggested that hardening of the cephalic and thoracic cuticles in C. olivaceous constitutes a protection during those periods when these parts are exposed to the environment.

Journal ArticleDOI
TL;DR: In this article, the rate constants and activation parameters for the aquation of trans-halogenoaminebis (dimethylglyoximato)-cobalt(III) complexes have been determined at 30°C and 0·1 M ionic strength at 8 < pH < 13.

Journal ArticleDOI
TL;DR: In this paper, the structural parametric estimators of a linear explosive model generating a pair of related stochastic processes are discussed, and some results of similar interest on the structural estimators are discussed.
Abstract: Linear explosive stochastic difference equations have been studied by White [6], Anderson [1], Rao [3] and the author [4], [5], leading to the derivation of limit distributions of certain sample functions bearing on structural estimation and goodness of fit tests. In this paper the author discusses certain results of similar interest on the structural parametric estimators of a linear explosive model generating a pair of related stochastic processes.

Journal ArticleDOI
TL;DR: In this paper, the simultaneous uncertainties of generalized cosine and sine operators are studied, and the authors obtain states which minimize (ΔC)2 ( ΔS)2/2/ 2; these states are characterized by a complex number λ and form an over-complete set within an ellipse in the λ-plane.
Abstract: In this paper the simultaneous uncertainties of the generalized cosine and sine operators are studied. We obtain states which minimize (ΔC)2 (ΔS)2/ 2; these states are characterized by a complex number λ and form an over-complete set within an ellipse in the λ-plane.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the vector transformation property of the electromagnetic potentials, together with the invariance of their two-point Wightman functions (in momentum space) make it impossible to have any nontrivial scheme of quantization in which the metric is positive-definite or even semidefinite.
Abstract: Considering the little group of the Poincar\'e group associated with a lightlike four-vector, we determine explicitly, in global form, the representation of this little group over the space of covariant massless fields transforming according to some irreducible representation ${D}^{(m,n)}$ of the homogeneous Lorentz group. The little-group representation is indecomposable and nonunitary. Exploiting the knowledge of this representation for ${D}^{(\frac{1}{2},\frac{1}{2})}$ (i.e., vector fields), we prove that the vector transformation property of the electromagnetic potentials ${A}_{\ensuremath{\mu}}$ together with the invariance of their two-point Wightman functions (in momentum space) make it impossible to have any nontrivial scheme of quantization in which the metric is positive-definite or even semidefinite. The proof does not involve any axioms beyond those required for the definition and invariance of the Wightman functions; in particular, we do not assume the spectral condition, local commutativity, or any equations of motion or constraint.

Journal ArticleDOI
TL;DR: In this article, the Lagrangian density of a nonlinear water wave with the lagrangians density L = 1/2((( delta mu phi )( delta mphi )-m2 phi 2)/(1+ lambda phi) 2)).
Abstract: Whitham's theory of nonlinear water waves is applied to a classical field with the lagrangian density L=1/2((( delta mu phi )( delta mu phi )-m2 phi 2)/(1+ lambda phi 2)). This is the isoscalar analogue of a chiral invariant SU(2)(X)SU(2) lagrangian with symmetry breaking term included. The corresponding field equation admits simple harmonic plane-wave solutions. The author found that the important field quantities of these waves, namely the wavenumber k and amplitude A obey a system of first- order partial differential equations. When the coupling parameter lambda is negative in sign, the system is hyperbolic, which implies that any inhomogeneities in k and A propagate with certain (amplitude-dependent) velocities. These velocities, which are the nonlinear generalization of the group velocity in the Whitham sense, are calculated.

Journal ArticleDOI
01 Oct 1974-Pramana
TL;DR: In this article, the representations of the Poincare group realized over the space of covariant fields transforming according to any irreducible representation are constructed explicitly with reference to a helicity basis.
Abstract: The representations of the Poincare group realized over the space of covariant fields transforming according to any irreducible representationD (m,n) of the Lorentz group are constructed explicitly with reference to a helicity basis The representation is indecomposable in the massless case The form of this representation together with the invariance of two-point Wightman functions of the field (which follows from a weak set of axioms) determines the metric structure in the space of quantum states of the field This structure is explicitly determined for generalD (m,n) Certain particular cases (especially the symmetric traceless tensor field) are discussed in detail Finally we consider the representation pertaining to massive fields, and examine the passage to the limit of vanishing mass We present a limiting procedure which leads from the unitary representation of the massive field to the indecomposable non-unitary representation of the massless field