Showing papers by "University of Valencia published in 1984"
TL;DR: In this paper, the Schmid model for homopolar optical-phonon scattering can explain the temperature dependence of electron mobility above 40 K and the optical phonon involved in the process is identified as the ${A}_{1}^{\ensuremath{'}}$ phonon with energy 143 meV.
Abstract: Electron scattering mechanisms in $n$-type indium selenide are investigated by means of the temperature dependence (4-500 K) of Hall mobility and the magnetic field dependence of Hall and magnetoresistance coefficients The Schmid model for homopolar optical-phonon scattering can explain the temperature dependence of electron mobility above 40 K The electron-phonon coupling constant is determined, ${g}^{2}=0054$ The optical phonon involved in the process is identified as the ${A}_{1}^{\ensuremath{'}}$ phonon with energy 143 meV The magnetic field dependence of Hall and magnetoresistance coefficients is discussed in terms of the Jones-Zener expansion
128 citations
TL;DR: Wall mannoproteins have been compared with those of the periplasmic space, most of the species being commonly present at both compartments and turnover of individual species has been studied by pulse and chase experiments.
95 citations
TL;DR: In this paper, the authors considered a version of the chiral bag model in which the interior quark sector is joined to an exterior meson sector through the requirement of continuity of the axial vector current at the bag surface.
76 citations
14 May 1984
TL;DR: It is shown here that termination of the rewriting relation and E-termination are the same whenever the used rewriting relation is E-commuting, a property inspired from Peterson and Stickel’s E-compatibility property.
Abstract: The problem of termination of a set R of rules modulo a set E of equations, called E-termination problem, arises when trying to complete the set of rules in order to get a Church-Rosser property for the rules modulo the equations. We first show here that termination of the rewriting relation and E-termination are the same whenever the used rewriting relation is E-commuting, a property inspired from Peterson and Stickel’s E-compatibility property. More precisely, their results can be obtained by requiring termination of the rewriting relation instead of E-termination if E-commutation is used instead of E-compatibility. When the rewriting relation is not E-commuting, we show how to reduce E-termination for the starting set of rules to classical termination of the rewriting relation of an extended set of rules that has the E-commutation property. This set can be classicaly constructed by computing critical pairs or extended pairs between rules and equations, according to the used rewriting relation. In addition we show that different orderings can be used for the starting set of rules and the added critical or extended pairs. Interesting issues for further research are also discussed.
53 citations
TL;DR: In this paper, gold-toned bipyramidal neurons of the dorsomedial cortex of Lacerta have been studied using light and electron microscopy, and the spines have been classified as stubby, mushroom-shaped or thin.
Abstract: Gold-toned bipyramidal neurons of the dorsomedial cortex of Lacerta have been studied using light and electron microscopy. The spines have been classified as stubby, mushroom-shaped or thin. Thin and mushroom-shaped spines are only found on proximal and intermediate dendritic segments, whereas stubby spines are found on distal dendritic segments. A Timm's method modification for electron microscopy (sulphide-osmium procedure) has been used. Timm-positive axonal endings usually synapse on thin and mushroom-shaped spines, whereas Timm-negative axonal endings usually synapse on stubby spines. Timm-positive afferents and their post-synaptic spines on bipyramidal neurons of Lacerta's dorsomedial cortex are compared with the corresponding elements on pyramidal neurons of the CA3 region of the hippocampus of mammals, on the basis of several histochemical and morphological studies. The possibility that these two neuronal types may be homologous is discussed.
41 citations
TL;DR: Changes in either pollinated or unpollinated and gibberellic acid (GA 3 )-treated ovaries were characterized by a rapid enlargement of mesocarpic cells and an increase in the number of cell ‘layers’ in the endocarp.
37 citations
01 Jan 1984
36 citations
TL;DR: The behaviour of the chromosomal polymorphism of D. subobscura was analyzed in relation to temporal changes, daily, seasonal and annual, in a natural population of Tibidabo.
Abstract: The behaviour of the chromosomal polymorphism of D. subobscura was analyzed in relation to temporal changes, daily, seasonal and annual. Firstly, chromosome analyses were carried out over a year in a natural population. Samples were taken at monthly intervals in Tibidabo, a locality close to Barcelona. In all the months except January, the number of individuals captured was enough to carry out a chromosome analysis of that population. The A, E and O chromosomes showed a great uniformity in the frequencies of gene arrangement over the year. However, significant changes occur in the frequencies of J and U chromosomes. The J1 and U1+2+8 arrangements showed a similar tendency, with two maxima, in June and February, and a minimum in September. These changes seem to be unrelated to the cyclical climatic changes. A chromosome analysis of the subsamples captured during the day, in the May sample, was done. In no case was the change in chromosome frequencies statistically significant. The behaviour of the Ust arrangement must be noted, the frequency of which decreased through the day. Finally, the data for the Tibidabo population were compared with samples captured in nearby localities over a period of 21 years. Significant differences were found in the frequencies of all the chromosomes, with the exception of J. The most differentiated population was the last sampled, from 1982. In this population the st arrangements tended to decrease in the A, E and O chromosomes and A2, E1+2+9+12 and O3+4+7 increase, respectively.
36 citations
TL;DR: The morphogenic capacity of Digitalis obscura leaf explants cultured in vitro has been studied, noting factors promoting the differentiation of roots, buds and shoots as well as those promoting callus proliferation.
Abstract: The morphogenic capacity of Digitalis obscura leaf explants cultured in vitro has been studied, noting factors promoting the differentiation of roots, buds and shoots as well as those promoting callus proliferation. Complete plant regeneration was obtained only by first culturing the leaf explants in a medium with NAA and BA to induce formation of buds, and subsequently transferring them to a medium without growth regulators to achieve the further development of shoots.
31 citations
TL;DR: In this paper, the pH dependence of the absorption and fluorescence spectra of the alkaloids harmaline and harmalol was investigated, and the p K a values associated with the ground state equilibria were determined spectrophotometrically.
29 citations
TL;DR: The combination of direct enrichment in NR10, followed by BSA or Hektoen enteric agar as plating media was most effective for the isolation of Salmonella.
Abstract: Alcaide, E., Martinez, J.P. & Garay, E. 1984. Comparative study on Salmonella isolation from sewage contaminated natural waters. Journal of Applied Bacteriology56, 365–371.
A comparative study of five factors influencing the isolation of salmonellas from sewage-contaminated natural waters was carried out. The effect of pre-enrichment in buffered peptone water was compared with single-step enrichment in NR10 broth incubated at 43dC. A modification of NR10 has been compared with the original composition. Bismuth sulphite agar (BSA), Hektoen enteric agar (HE) and brilliant green agar (BGA) have been used as plating media. Other factors considered have been temperature of the water and sampling site. A total of 759 salmonella strains belonging to 36 different serotypes has been recovered in a two-year study. All five factors considered in the study have shown a significant effect on the recovery of salmonellas. The combination of direct enrichment in NR10, followed by BSA or HE as plating media was most effective for the isolation of Salmonella. The influence of water temperature and characteristics of the sampling sites have also been discussed.
TL;DR: From the alcoholic extract of Centaurea aspera var stenophylla, the glucosides of sitosterol and stigmasterol were isolated and characterized as mentioned in this paper.
TL;DR: In this paper, the Steric interaction between the N-methyl group on the indole ring and the 1-substituent on the ethenyl group prevents the diene system adopting a coplanar cisoid configuration and thereby, inhibits the π4 + π2 cycloaddition reaction of the system with dimethyl acetylenedicarboxylate.
TL;DR: The anamorphic rotation-variant system produces a scaled Fourier transform F(u,mv) of an object f(x,y), where m is a scaling constant, and it is shown that the super resolution in one direction is gained by reducing the number of degrees of freedom of the optical message in the other.
Abstract: The idea of obtaining a nonsymmetric Fourier transform with crossed cylindrical lenses of different focal lengths is presented. The anamorphic rotation-variant system produces a scaled Fourier transform F(u,mv) of an object f(x,y), where m is a scaling constant. The system performs controlled angular magnification of an object spectrum. It is shown that the super resolution in one direction is gained by reducing the number of degrees of freedom of the optical message in the other. Experimental results are shown where the scaling constant m of up to 10 has been obtained.
TL;DR: It seems clear that the walls of yeast cells must be structurally and enzymatically a complex organelle, increased by the fact that different proteins with important roles in the cell economy as well as survival products are localized on the wall or in the periplasmic space.
Abstract: Yeast cells are covered by a rigid structure that protects the protoplast from osmotic changes and gives the characteristic shape to the cell. Studies on the composition of the wall of several species of yeast and other fungi have shown that they contain mainly polysaccharides with minor amounts of other materials. A completely rigid and continuous wall, nevertheless, would render growth impossible because cell extension would be restricted, so that an equilibrium must exist between softening (partial degradation) of wall and incorporation of new material into free ends of the polymers. From these considerations, it seems clear that the walls must be structurally and enzymatically a complex organelle. This complexity is increased by the fact that different proteins with important roles in the cell economy (e.g., invertase) and morphogenesis (β-glucanases) as well as survival products (e.g., killer, sexual factor) are localized on the wall or in the periplasmic space.
TL;DR: In this article, the second virial coefficients, A2, intrinsic viscosities, [η], and solvation preferential coefficients, γ, for the ternary systems n-hexane, HEX, (1)/butanone, MEK, (2)/poly(dimethylsiloxane), PDMS, (3) and n-heptane (HEP, HEP, 1)/MEK, 2)/PDMS (3), have been determined at 20.0°.
TL;DR: In this article, a lower bound for the ratio R>3.6×10−12|m2ν〉eμ|2 KeV4, where ǫ is the relevant off-diagonal leptonic mixing, was obtained.
TL;DR: In this article, the initial selectivity to cracking, isomerization and disproportionation, kinetic rate constants, activation energies and decay parameters have been calculated and compared with those obtained using a HY ultrastable zeolite as a catalyst.
TL;DR: In this paper, the energy barriers for internal rotation about the interannular single CC bond in bifurans were calculated by means of ab initio MO calculations.
Abstract: The energy barriers for internal rotation about the interannular single CC bond in bifurans were calculated by means of ab initio MO calculations. The STO-3G and 4-31G basis sets were used. Geometrical optimization of the most significant interannular internal parameters was performed with the STO-3G basis set. The calculated barrier heights, relative to cis conformer energies, follow the sequence 2,3′- > 2,2′- > 3,3′- and have the values of 4.2, 3.7 and 3.3 kcal mol−1, respectively. The same sequence holds for 4-31G calculations but very significant differences are obtained for the 3,3′-bifuran barrier height and for the 2,2′-bifuran relative cis—trans stability. The 4-31G barrier height values were 4.5, 3.4 and 0.8 kcal mol−1, respectively. In all calculations, trans conformers appeared to be more stable than cis except for 2,3′-bifuran, where the opposite is true. Finally, the MO structures of the highest occupied MOs of bifurans are discussed on the basis of the electronic structure of furan.
TL;DR: In this article, the sesquiterpene lactones have been synthesized from (-)-artemisin, including (+)-Temisin, (+)-melitensin, and related sesQUITENSIN.
TL;DR: It was shown that metal-containing boutons which would be labelled when using the Timm method, could be labelled by the sulphide-osmium procedure as well, i.e. perfusion and immersion in a glutaraldehyde fixative saturated with H2S vapour and then osmium postfixation.
TL;DR: In this article, the cosolvent character of n-undecane(1)/butanone(2)/poly(dimethylsiloxane) (3) has been determined at 20.0°C, as the inversion in λ and the maxima in A2 and in [η, at o 10 ⋍0.65, seem to indicate.
TL;DR: In this paper, a cyclometallation of a solution of the complex Rh(oq)(CO)(PCBr), (PCBr = 2-bromo-3,4,5,6-tetrafluorophenyldiphenylphosphine; oq = 8-hydroxyquinolinate) in toluene is refluxed.
TL;DR: In this article, the authors show that there is occupational preference for the two coordination sites in the crystalline structure of EDTA · 6H2O compounds, which can be described as ordered alternating-heterobimetallic polymeric coordination complexes.
Abstract: Polymetallic solid solutions of the ethylenediaminetetracetic acid (EDTA) and six divalent metal ions exist in the range: MgαMnβCoγZnδNieCuτ(EDTA) · 6H2O where α + β + γ + δ + e + τ=2, 0⩽τ⩽1, 0⩽γ,e,δ⩽2, 0⩽α, β⩽1. This type of structure is characterized by the presence of two different octahedral carboxylate-bridged coordination sites forming infinite zig-zag chains. Visible and i.r. spectra and t.g.a. analysis show that there is occupational preference for the two coordination sites in the crystalline structure. Due to this preference, and also to the structural features, the heterobimetallic MM′(EDTA) · 6H2O compounds constitute a structurally new class of materials which can be described as ordered alternating-heterobimetallic polymeric coordination complexes.
TL;DR: In this paper, the authors improved upon a previous analysis of the mixing in nuclei and provided an estimate, as reliable as possible, in the n n oscillation time τ n n exploiting the experimental data on nuclear stability.
TL;DR: The results suggest that the uterine inhibitory action of histamine and 4-methylhistamine is mediated through catecholamine release and direct stimulation of the H2-receptors, and the effect of 2-(2-pyridyl) ethylamine is only mediated by release catechlamine.
TL;DR: In this article, the π and σ-coordinated complexes for the copper-I-ethylene system were studied by a pseudopotential ab initio MO method and it was found that the lowest energy structure shows a bent C2v conformation.
TL;DR: In this article, a symmetrical C 2V hydrogen-bonded structure is found to be the most stable and a barrier height of 4.0 kcal mol −1 is obtained with the 4-31G basis set for the single-minimum hydrogen potential energy curve.
Abstract: Ab initio calculations have been performed on malonic and hydrogen malonate acids. The studied conformations were optimized at the STO-3G level and the STO-3G optimal geometries used for single point 4-31G calculations. For malonic acid the most stable conformation occurs in the absence of hydrogen bonding. In hydrogen malonate acid a symmetrical C 2V hydrogen-bonded structure is found to be the most stable and a barrier height of 4.0 kcal mol −1 is obtained with the 4-31G basis set for the single-minimum hydrogen potential energy curve.
TL;DR: In this article, the K and a constants of the Mark-Houwink equation have been evaluated over the whole composition range of the binary solvent mixtures, and polymer (mixed solvent) interaction parameters and unperturbed dimensions were evaluated both from A2 and [η] data, the feasibility of A2 evaluation from [ η] experimental data or vice versa being discussed.
TL;DR: In this paper, a chiral soliton mechanism was proposed for n-quark systems in the chiral bag model, where the hedgehog ansatz for the Goldstone pion field was used to handle the nonlinearities of the model.