Showing papers by "Tel Aviv University published in 1982"
TL;DR: The extraction of chlorophylls in higher plant tissue using N,N-dimethylformamide expedites the process and enables the determination of small samples with low pigment level, and formulae for quantitative determination of pigments concentrations were developed.
Abstract: The extraction of chlorophylls in higher plant tissue using N,N-dimethylformamide expedites the process and enables the determination of small samples with low pigment level.Absorption spectra of Chl a, Chl b, and Pchl and of their acidified derivatives, the phaeophytins, were recorded. Conversion of Chl b to its corresponding acidified product occurs much more slowly than that of Chl a and Pchl. When acidified, Pchl differs from Chl a and Chl b by the disappearance of the red band in the absorption spectrum. Specific extinction coefficients were determined and formulae for quantitative determination of pigments concentrations were developed. When concentrations of pigments are low, as in etiolated plant material, the absorption spectra of the chlorophylls can be distorted due to the presence of other substances simultaneously extracted; formulae for pigment determination under such circumstances were also derived.
1,144 citations
TL;DR: In this article, the authors present a systematic expansion for studying an infrared-stable fixed point of gauge theories with massless fermions and show that the transition between chirally symmetric and asymmetric phases is generally first order.
911 citations
TL;DR: The effect of periodic two-dimensional excitation on the development of a turbulent mixing region was studied experimentally in this article, where controlled oscillations of variable ampli- tude and frequency were applied at the initiation of mixing between two parallel air streams.
Abstract: The effect of periodic two-dimensional excitation on the development of a turbulent mixing region was studied experimentally. Controlled oscillations of variable ampli- tude and frequency were applied at the initiation of mixing between two parallel air streams. The frequency of forcing was at least an order of magnitude lower than the initial instability frequency of the flow in order to test its effect far downstream. The effect of the velocity difference between the streams was also investigated in this experiment. A typical Reynolds number based on the velocity difference and the momentum thickness of the shear layer was l04.It was determined that the spreading rate of the mixing layer is sensitive to periodic surging even if the latter is so small that it does not contribute to the initial energy of the fluctuations. Oscillations at very small amplitudes tend to increase the spreading rate of the flow by enhancing the amalgamation of neighbouring eddies, but at higher amplitudes the flow resonates with the imposed oscillation. The resonance region can extend over a significant fraction of the test section depending on the Strouhal number and a dimensionless velocity-difference parameter. The flow in the resonance region consists of a single array of large, quasi-two-dimensional vortex lumps, which do not interact with one another. The exponential shape of the mean-velocity distribution is not affected in this region, but the spreading rate of the flow with increasing distance downstream is inhibited. The Reynolds stress in this region changes sign, indicating that energy is extracted from the turbulence to the mean motion; the intensity of the spanwise fluctuations is also reduced, suggesting that the flow tends to become more two-dimensional.Amalgamation of large coherent eddies is resumed beyond the resonance region, but the flow is not universally similar. There are many indications suggesting that the large eddies in the turbulent mixing layer at fairly large Re are governed by an inviscid instability.
648 citations
421 citations
TL;DR: In this article, a new approach to the understanding of sociological collective behaviour based on the framework of critical phenomena in physics is presented, where a simple mean-behaviour model is applied to a strike process in a plant.
Abstract: A new approach to the understanding of sociological collective behaviour, based on the framework of critical phenomena in physics, is presented. The first step consists of constructing a simple mean‐behaviour model and applying it to a strike process in a plant. The model comprises only a limited number of parameters characteristic of the plant considered and of the society. A dissatisfaction function is introduced with a basic principle stating that the stable state of the plant is a state which minimizes this function. It is found that the plant can be in one of two phases: the “collective phase” and the “individual phase.” These two phases are separated by a critical point, in the neighbourhood of which the system is very sensitive to small changes in the parameters. The collective phase includes a region of parameters for which the system has two possible states: a “work state” and a “strike state.” The actual state of the system depends on the parameters and on the “history of the system.” The irreve...
397 citations
TL;DR: In this article, strict separation by a cone is used to redefine proper efficiency and two versions of the properness, which unify and generalize known definitions, are presented, and necessary and sufficient conditions for the existence of the set of properly efficient decisions and characterization of this set in terms of the supports of the decision set are given.
Abstract: Strict separation by a cone is used here to redefine proper efficiency. Two versions of the properness, which unify and generalize known definitions, are presented. Necessary and sufficient conditions for the existence of the set of properly efficient decisions and characterization of this set in terms of the supports of the decision set are given.
277 citations
TL;DR: In this article, a family of boundary conditions which simulate outgoing radiation are derived and applied to the computation of steady state flows and are shown to significantly accelerate the convergence to steady state.
274 citations
TL;DR: In this article, the authors provided estimates on the dust transport to the eastern Mediterranean are provided, which were obtained from several studies concerned with dust storms in Israel including: ground and airborne particle mass concentration, vertical profiles, dust storm trajectories, particle deposition and the climatology of dust storms.
265 citations
TL;DR: In this paper, the bulk effective dielectric constant of a two-phase composite material is derived under various assumptions about the available information, and the question of optimality of the bounds and their connection to solvable microgeometries is discussed.
224 citations
TL;DR: It is shown that it is NP-hard to find r lines so as to minimize any isotone function of the distances between given points and their respective nearest lines.
202 citations
TL;DR: In this article, a higher order continuum theory with microstructure is derived for the modeling of the 3D motion of fiber-reinforced composites in which both the matrix and fibers constituents are assumed to be elastic-viscoplastic work-hardening materials.
TL;DR: The data demonstrate that the thin fimbriae of RAG-1 are a major factor in adherence to polystyrene and hydrocarbon, may be crucial in enabling growth of cells on hexadecane, and constitute the major cell surface agglutinogen.
Abstract: Acinetobacter calcoaceticus RAG-1, a hydrocarbon-degrading bacterium which adheres avidly to hydrocarbons and other hydrophobic surfaces, possesses numerous thin fimbriae (ca. 3.5-nm diameter) on the cell surface. MR-481, a nonadherent mutant of RAG-1 which is unable to grow on hexadecane under conditions of limited emulsification and low initial cell density, lacks these fimbriae. Prolonged incubation of MR-481 in hexadecane medium enriched for partial adherence revertants. The reappearance of thin fimbriae was observed in all such revertant strains. RAG-1 cells and partial revertant strains were agglutinated in the presence of antibody, whereas MR-481 cells were not. Another mutant, AB15, which was previously isolated on the basis of its nonagglutinability in the presence of antibody, also lacked thin fimbriae and was conditionally nonadherent. Furthermore, strain AB15 was unable to grow on hexadecane medium. Adherence of RAG-1 cells to hexadecane was considerably reduced after shearing treatment. The material removed from the cell surface by shearing of RAG-1 and the partial revertant strains yielded a single antigenic band in RAG-1 and partial revertant strains, as observed by crossed immunoelectrophoresis. This band was absent in both fimbriae-less mutants, MR-481 and AB15. The data demonstrate that the thin fimbriae of RAG-1 (i) are a major factor in adherence to polystyrene and hydrocarbon, (ii) may be crucial in enabling growth of cells on hexadecane, and (iii) constitute the major cell surface agglutinogen.
TL;DR: In this paper, the experimental results compare resonably well with the theoretical model for the prediction of flow pattern in vertical downward flow, and theoretically based transition criteria for the flow pattern are presented.
TL;DR: In this article, a field experiment was conducted in order to replicate the conventional Pygmalion effect and to test the effects on learning performance of directly inducing high self-expectancy among trainees themselves.
TL;DR: In this paper, the flow pattern transition for gas liquid flow in pipes for downward 0-90° inclination was studied and mathematical models were developed to predict the flow patterns in the whole range of downward inclination.
TL;DR: In this paper, a dynamic incentive generating penalty system was proposed for income tax evasion, which, if instituted, may reduce, at a given cost, the generation of undesirable externalities.
TL;DR: The results indicate that the brain sites for inhibitory effect of melatonin on dopamine neurosecretion overlap the sites reportedly involved in its modulation of neuroendocrine functions.
TL;DR: It is concluded that a bone biopsy provides useful information for the diagnosis, classification and staging of patients with multiple myeloma.
Abstract: A study has been made of 420 bone marrow biopsies from patients with multiple myeloma (220), idiopathic monoclonal gammapathy (50), reactive plasmacytosis (42) and solitary plasmacytoma (22) Histology and immunohistological parameters were more reliable than cytology in distinguishing a reactive from a neoplastic plasmacytosis Histological variables were correlated with the clinical features of the patients to determine the factors which were of value in predicting prognosis Plasma cell maturity and the extent of infiltration in the biopsy by myeloma cells proved to be highly significant in predicting the duration of survival On the basis of these criteria multiple myeloma was classified into two types: plasmacytic of low-grade malignancy and plasmablastic of high-grade malignancy; and into three stages which accurately reflected the progression of the disease We conclude that a bone biopsy provides useful information for the diagnosis, classification and staging of patients with multiple myeloma
TL;DR: In this article, the problem of obtaining maximum likelihood estimates (MLE) for the parameters of log-linear models under this type of incomplete data is addressed and the appropriate systems of equations are presented and the expectation-maximization (EM) algorithm (Dempster, Laird, and Rubin 1977) is suggested as one of the possible methods for solving them.
Abstract: In many studies the values of one or more variables are missing for subsets of the original sample. This article focuses on the problem of obtaining maximum likelihood estimates (MLE) for the parameters of log-linear models under this type of incomplete data. The appropriate systems of equations are presented and the expectation-maximization (EM) algorithm (Dempster, Laird, and Rubin 1977) is suggested as one of the possible methods for solving them. The algorithm has certain advantages but other alternatives may be computationally more effective. Tests of fit for log-linear models in the presence of incomplete data are considered. The data from the Protective Services Project for Older Persons (Blenkner, Bloom, and Nielsen 1971; Blenkner, Bloom, and Weber 1974) are used to illustrate the procedures discussed in the article.
TL;DR: The findings show that the combining site of the E. coli lectin is an extended one, corresponding to the size of a trisaccharide, that it contains a hydrophobic region, and that it is in the form of a pocket on the surface of the lectin.
TL;DR: Although both aliphatic and aromatic hydrocarbon emulsions were stabilized by emulsin, mixtures containing both aliphatics and aromatics were better substrates for emulsan than the individual hydrocarbon by themselves.
Abstract: Emulsan is a polymeric extracellular emulsifying agent produced by Acinetobacter RAG-1. Hydrocarbon-in-water emulsions (V(f) of hydrocarbon of 0.01-0.10) were stabilized by small quantities of emulsan (0.02-0.2 mg/mL). Although both aliphatic and aromatic hydrocarbon emulsions were stabilized by emulsan, mixtures containing both aliphatics and aromatics were better substrates for emulsan than the individual hydrocarbon by themselves. The emulsan remained tightly bound to the hydrocarbon even after centrifugation as determined by (a) residual emulsan in the aqueous phase and (b) the fact that the resulting "cream" readily dispersed in water to reform stable emulsions. With hexadecane-to-emulsan weight ratio of 39 and 155, the noncoalescing oil droplets had average droplet diameters of 2.0 and 4.0 microm, respectively. Dialysis studies showed that the water-soluble dye Rhodamine B adsorbed tightly to the interface of hexadecane-emulsan droplets although the dye did not bind to either hexadecane or emulsan alone. At saturating concentrations of dye, 2.2 micromol of dye were bound per mg emulsan.
TL;DR: Strain BD413 either produces a modified extracellular polysaccharide or excretes an additional substance(s) that is responsible for the emulsifying activity and emulsions induced by the ammonium sulfate-precipitated BD413extracellular emulsifier require the presence of magnesium ion and a mixture of an aliphatic and an aromatic hydrocarbon.
Abstract: The heavily encapsulated Acinetobacter calcoaceticus BD4 and the “miniencapsulated” single-step mutant A. calcoaceticus BD413 produced extracellular polysaccharides in addition to the capsular material. The molar ratio of rhamnose to glucose (3:1) in the extracellular BD413 polysaccharide fraction was similar to the composition of the capsular material. In both strains, the increase in capsular polysaccharide was parallel to cell growth and remained constant in stationary phase. The extracellular polysaccharides were detected starting from mid-logarithmic phase and continued to accumulate in the growth medium for 5 to 8 h after the onset of stationary phase. Strain BD413 produced one-fourth the total rhamnose exopolysaccharide per cell that strain BD4 did. Depending on the growth medium, 32 to 63% of the rhamnose polysaccharide produced by strain BD413 was extracellular, whereas in strain BD4 only 7 to 14% was extracellular. In all cases, strain BD413 produced more extracellular rhamnose polysaccharide than strain BD4 did. In glucose medium, strain BD413 also produced approximately 10 times more extracellular emulsifying activity than strain BD4 did. The isolated capsular polysaccharide obtained after shearing of BD4 cells showed no emulsifying activity. Thus, strain BD413 either produces a modified extracellular polysaccharide or excretes an additional substance(s) that is responsible for the emulsifying activity. Emulsions induced by the ammonium sulfate-precipitated BD413 extracellular emulsifier require the presence of magnesium ion and a mixture of an aliphatic and an aromatic hydrocarbon.
TL;DR: In this article, the rate of diffusion to ensembles of microelectrodes is calculated by digital simulation, based on the explicit finite-difference technique, and the results are compared with previous calculations based on analytical solutions, which were derived on the basis of different approximations.
TL;DR: In this article, the effect of complex coupling coefficients on the performance of distributed feedback (DFB) lasers is studied, and the physical origins of a complex coupling coefficient and its relation with gain or loss mechanisms which occur inside the laser are discussed.
Abstract: The effect of complex coupling coefficients on the performance of distributed feedback (DFB) lasers is studied. The physical origins of a complex coupling coefficient are specified, and its relation with gain or loss mechanisms which occur inside the laser is discussed. Numerical results are presented for the oscillation frequencies, threshold gains, and intensity patterns of the longitudinal modes of the DFB laser.
TL;DR: Although the survival ability of a dispersed offspring is reduced (compared to that of a non-dispersed offspring), the optimal strategy implies that a substantial part of the progeny will be dispersed.
TL;DR: The relationship between the undulatory nature of inclined thin film flows and the transfer characteristics have been demonstrated and qualitatively established as discussed by the authors, which provides a basis for future analytical treatments of the hydrodynamics of wavy flows and their influence on the transport phenomena.
TL;DR: In this paper, the authors extend the study of the highest weight representations of a finite-dimensional complex semisimple Lie algebra 9 to a Kac-Moody algebra and to a contragredient Lie algebra G(A) corresponding to a square matrix A over C.
TL;DR: The probability that tax evasion will be detected and fined appears to be a more effective deterrent than the size of such fines, although both the magnitude of finm and their probability affect tax evasion.
Abstract: In a pame-simulation context, tax evasion behavior of 13 subjects was observed. The probability that tax evasion will be detected and fined appears to be a more effective deterrent than the size of such fines, although both the magnitude of finm and their probability affect tax evasion. Vague information about the probability that fines will be imposed enhances the deterrent power of low probability audits and small fines.
TL;DR: Using the strong surface-tension approximation, an asymptotic equation which describes the evolution of the disturbed surface of a film ζ = Φ(ξ, η, τ) flowing down an infinite vertical column was derived in this paper.
Abstract: Using the strong surface-tension approximation, an asymptotic equation is derived which describes the evolution of the disturbed surface of a film ζ = Φ(ξ, η, τ) flowing down an infinite vertical column. In non-dimensional scaled variables this equation is Φτ + ΦΦξ + Φ ξξ + (1/μ2) ∇2Φ + ∇ 4Φ = 0, where (ξ, η) are cartesian coordinates on the surface of the cylinder, - ∞ μc the one-dimensional nature of the flow disappears, and at μ >> μc the film surface is expected to assume the form of down-flowing drops in a state of irregular splitting and merging.
TL;DR: In this paper, the authors analyzed job satisfaction and some of its correlates among Canadian chartered accounts (CAs) focusing on the formulation and examination of influence paths between professional commitment, work need deprivation, organizational commitment, job satisfaction, and intention to leave the organization (migrate).
Abstract: This study analyzes job satisfaction and some of its correlates among Canadian chartered accounts (CAs). It focuses on the formulation and examination of influence paths between professional commitment, work need deprivation, organizational commitment, job satisfaction and intention to leave the organization (migrate). The empirical model with respect to the total sample mostly replicated the theoretical one. Migration tendencies of partners and sole practitioners in public practice were found unrelated to their job satisfaction and organizational commitment. Such tendencies of CAs in industry and government as well as those of employees in CA firms were related to their organizational commitment only. Professional commitment of CAs in nonprofessional organizations was found unrelated to the study variables.