Showing papers by "Ben-Gurion University of the Negev published in 1979"

Isolation and characterization of phycocyanins from the blue-green alga Spirulina platensis

Abstract: Two main biliproteins c-phycocyanin and allophycocyanin were identified and characterized in the blue-green alga Spirulina platensis. The specific absorbance, fluorescence maxima, sub-unit make-up and amino acid composition of the biliproteins in Spirulina platensis resemble those reported for other blue-green algae. However, the minimum molecular weights (44,000 for c-phycocyanin and 38,000 for the allophycocyanin) and the specific extinction coefficients (73, and 58 for c-phycocyanin and allophycocyanin respectively) of these biliproteins were different from these values in other blue-green algae.

The influence of austenite stability on the hydrogen embrittlement and stress- corrosion cracking of stainless steel

Abstract: A study has been made of the HE and SCC of a type 304 and a type 310 austenitic stainless steel, and the results correlated with the presence or absence of α′ martensite, determined by means of a ferrite detector. Hydrogen induced slow crack growth (SCG) was observed at room temperature when type 304 was stressed i) in 1 psig (∼105 N/m2) gaseous hydrogen, ii) after high temperature charging, and iii) while undergoing cathodic charging. The fracture surfaces corresponding to SCG were primarily transgranular and cleavage-like, and were found to be associated with α′. Conditions i) to iii) did not produce SCG in the type 310 steel, in which α′ martensite was not detected, nor did SCG occur when type 304 was stressed in gaseous hydrogen above the MD temperature (∼110°C). These observations indicated that the formation of the martensitic phase was a prerequisite for SCG under these test conditions. Stressing of type 310 while it was undergoing cathodic charging at room temperature was found to produce shallow, nonpropagating cracks, confirming earlier reports that austenite can be embrittled by hydrogen in the absence of α′. SCC occurred in both alloys in boiling aqueous MgCl2 (154°C) with no evidence for α′ formation. The results are discussed in terms of the mechanisms of HE and SCC.

The facilities layout problem: a multi-goal approach

Abstract: This paper presents a combined quantitative and qualitative (subjective) approach to the plant layout problem. The two objectives, which may be conflicting, are minimizing the material handling cost and maximizing a closeness rating measure. A heuristic algorithm is developed which results in a discrete efficient frontier set, including only 'efficient layouts’. By specifying the different weights, or range of weights, for these goals, the 'best’ solution (layout) is generated.

SALT TOLERANCE IN THE WILD RELATIVES OF THE CULTIVATED TOMATO: PROLINE ACCUMULATION IN LYCOPERSICON ESCULENTUM MILL., L. PERUVIANUM MILL. AND SOLANUM PENNELLI COR. TREATED WITH NaCI AND POLYETHYLENE GLYCOLE

Abstract: Summary The cultivated tomato Lycopersicon esculentum cv. Rhemlands Ruhm and the two wild species L. peruvianum and Solomon pelnnellii which originated in dry habitats were compared with respect to accumulation of free proline, chloride and succulence under NaCl stress, and accumulation of proline and succulence under water stress produced by polyethylene glycole. Proline accumulation increased in all three species under both types of stress. Increase under salinity stress, however, was smaller in the two wild species which accumulated more chloride and were more succulent. Under water stress, the increase of proline level was greatest in is. pennellii, in which succulence decreased drastically, and smallest in L. peruvianum. The possible role of salt tolerance in enabling wild tomato species to endure drought, and the difference between them with respect to proline accumulation, are discussed.

A simplified theory of the optogalvanic effect

Abstract: We present a simple phenomenological theory of the optogalvanic effect based on the multiplication of an electron within the plasma. The dependence of the signal on current and pressure and its temporal behavior are predicted for atoms irradiated by chopped CW lasers and pulsed lasers. Experimental data obtained by pulsed lasers are presented and interpreted.

Anisotropic Spin-Glass Behavior in Fe 2 Ti O 5

Abstract: It is shown that the insulating oxide ${\mathrm{Fe}}_{2}$Ti${\mathrm{O}}_{5}$ exhibits anisotropic (uniaxial) spin-glass behavior below 55 K. Extensive experimental results supporting this conclusion, including principal magnetic susceptibility, neutron scattering, ultrasonic, specific heat, and oriented single-crystal M\"ossbauer measurements, are described.

Mixing properties of Markov operators and ergodic transformations, and ergodicity of cartesian products

Abstract: LetT be a Markov operator onL 1(X, Σ,m) withT*=P. We connect properties ofP with properties of all productsP ×Q, forQ in a certain class: (a) (Weak mixing theorem)P is ergodic and has no unimodular eigenvalues ≠ 1 ⇔ for everyQ ergodic with finite invariant measureP ×Q is ergodic ⇔ for everyu ∈L 1 with∝ udm=0 and everyf ∈L ∞ we haveN −1Σ ≠1/ ||→0. (b) For everyu ∈L 1 with∝ udm=0 we have ‖T nu‖1 → 0 ⇔ for every ergodicQ, P ×Q is ergodic. (c)P has a finite invariant measure equivalent tom ⇔ for every conservativeQ, P ×Q is conservative. The recent notion of mild mixing is also treated.

Rotational distributions from photodissociations. I. Linear triatomic molecules

Abstract: The generalized Franck–Codon theory of the collinear dissociation of linear triatomic molecules is presented, including a proper description of the bending vibrations in the initial bound electronic state and of the rotational motions on both the initial and the final repulsive electronic surface. The nonseparable multidimensional bound–continuum Franck–Condon integrals are reduced to a rapidly convergent series of products of one dimensional integrals. Analytical expressions are derived for rotational and orbital angular momentum distributions of the products, for scalar coupling (as in predissociations), as well as parallel and perpendicular transitions (as in direct photodissociation). This fully quantum mechanical theory makes explicit the separate and interrelated roles played by angular momentum and energy conservation. The present work is applied in a separate paper to the photodissociation of ICN, and qualitative agrement with experiment is obtained.

Modest theory of short chains. ii

Abstract: We analyse here the monadic theory of the rational order, the monadic theory of the real line with quantification over "small" subsets and models of these theories. We prove that the results are in some sense the best possible. ?0. Introduction. A chain is a linearly ordered set. A chain is short iff it embeds neither Wi nor O1. Shortness is expressible in the monadic language of order. For convenience, we shall use the term "chain" to mean "short chain". Modest chains are defined in ?2. A chain is modest iff it is p-modest for every posi- tive integer p; p-modesty is expressible in the monadic theory of order. Let R be the real line. Set X c R will be called pseudo-meager iff it is a union of less than c (the cardinality of continuum) nowhere dense subsets. It is well known that the hypothesis "R is not pseudo-meager" can be neither proved nor disproved in ZFC. The Continuum Hypothesis (or Martin's Axiom, see (MS)) implies that each pseudo-meager set is meager. By the Baire Theorem, R is not meager. Let Q be the chain of rational numbers. The monadic theory of Q is decidable (see (Ra)) but not categorical. By (Sh), there exist nonseparable chains monadically equivalent to Q (i.e. having the same monadic theory as Q) and if R is not pseudo- meager then there are subchains of R of cardinality c monadically equivalent to Q. THEOREM 1 (SEE ?3). A chain is monadically equivalent to Q iff it is modest and has neither jumps nor endpoints. Moreover there exists an algorithm associating a pair (p, s) with each sentence SD in the monadic language of order in such a way that either = 0 and all p-modest chains without jumps and endpoints satisfy q or c = 1 and all these chains do not satisfy q.

Abnormal Stomatal Behavior and Hormonal Imbalance in flacca, a Wilty Mutant of Tomato: V. Effect of Abscisic Acid on Indoleacetic Acid Metabolism and Ethylene Evolution.

Abstract: The wilty tomato mutant flacca , the normal cultivar Lycopersicon esculentum Mill. Rheinlands Ruhm, and abscisic acid-induced phenotypic revertants were compared with respect to ethylene evolution, activity of tryptophan aminotransferase, and [1- 14 C]indoleacetic acid decarboxylation. The level of ethylene evolution was higher in flacca plants than in the normal cultivar. Ethylene evolution was reduced to the wild type level in abscisic acid-induced phenotypic revertants and to a lesser extent in mutant plants grown under humid conditions. Leaf epinasty, which characterized flacca plants in the present experiments, did not appear in absciscic acid-treated mutant plants, but did appear under high humidity. Tryptophan aminotransferase activity, similar to ethylene evolution, was higher in flacca plants and was reduced to the normal level by abscisic acid treatment. Indoleacetic acid decarboxylation was similar in mutant and normal plants, but was increased by abscisic acid treatment. The relationships among ethylene, auxin, and the morphological symptoms which characterize the mutant are discussed.

The Family as an Incomplete Annuities Market

Abstract: A new empirical study of the relation between money, nominal income, prices, and real output in postwar quarterly U.S. data rejects virtually all of the conclusions reached by Families provide individuals with risk sharing opportunities which may not otherwise be available. Within the family there is a degree of trust and a level of information which alleviates three key problems in the provision of insurance by markets open to the general public, namely, moral hazard, adverse selection, and deception. The informational advantages of pooling risk within families must be set against the inability of families to provide complete insurance because of the small size of the risk pooling group. This paper demonstrates how families can provide insurance against uncertain dates of death. Death risk sharing family arrangements effectively constitute an incomplete annuities market. Our analysis indicates that these arrangements even in small families can substitute by more than70% for complete annuities. Given the adverse selection problem and transactions costs in public annuity markets, risk pooling in families may well be preferred to purchasing market annuities. In the absence of organized public markets in annuities, these risk sharing arrangements provide powerful economic incentives for marriage and family formation. The paper suggests that inter-family transfers need have nothing to do with altruistic feelings; rather, they may simply reflect risk sharing behavior of completely selfish family members.

Rotational distributions from photodissociation. II. Results for ICN+hν→l+CN(X 2Σ+)

Abstract: The quantum theory of rotational, vibrational, translational and electronic energy distributions in photodissociation is applied to the A continuum photodissociation of ICN. Excited state potential energy surfaces are fitted to the available experimental data, and predictions are made of the product energy distributions. General results are discussed which are applicable to other photodissociations and predissociations. In particular, the calculated rotational energy distributions display a strong sensitivity to the details of the unbound potential surface. The results of the collinear approximation for vibrational distributions in photodissociation of linear molecules are shown to be considerably modified by including rotational degrees of freedom, especially at high photon energies.The quantum theory of rotational, vibrational, translational and electronic energy distributions in photodissociation is applied to the A continuum photodissociation of ICN. Excited state potential energy surfaces are fitted to the available experimental data, and predictions are made of the product energy distributions. General results are discussed which are applicable to other photodissociations and predissociations. In particular, the calculated rotational energy distributions display a strong sensitivity to the details of the unbound potential surface. The results of the collinear approximation for vibrational distributions in photodissociation of linear molecules are shown to be considerably modified by including rotational degrees of freedom, especially at high photon energies.

Binding of imipramine to plasma proteins: effect of hyperlipoproteinemia.

Abstract: The binding of imipramine to plasma proteins was studied by equilibrium gel filtration Imipramine was highly bound to lipoproteins as well as to other plasma proteins The binding to the lipoproteins was higher in hyperlipoproteinemic patients than in normal subjects and correlated well with both plasma cholesterol and triglyceride levels The overall percent binding of imipramine was also higher in hyperlipoproteinemic patients than in normal subjects It is concluded that the varying degree of binding of imipramine to plasma proteins as a result of varying lipoprotein concentrations, as well as the special nature of the binding to lipoproteins, may be of kinetic and possibly clinical significance in hyperlipoproteinemic individuals

Theoretical considerations on mechanical parameters of joint surfaces based on studies on ceramics

Abstract: Morphological features of brittle fracture in glass, ceramics and rocks include fracture origin, mirror plane, mist, hackle, radial striations and concentric undulations. The plume structure which characterizes many joint surfaces is analogous to striations or ‘grainy steps’ developed on fracture surfaces of ceramics. Joint surfaces with plumose structures result essentially from tensile failure, but may also be affected by shear stresses. The ellipticity of the plumose structure commonly observed reflects a region of secondary tensional strain parallel to bedding developed due to anisotropic elastic properties of the rock as a result of formational loading. Striations and hackles may have similar orientations. A distinction between them is important since hackles on a joint surface indicate a rapid fracture whereas striations can result from a slow fracture. Intense undulations without hackling may indicate a slow fracture. A smooth mirror plane on a joint surface indicates that while the fracture had been formed, stresses had reached a certain maximum and then subsided. On the other hand, a joint surface that shows a mirror plane with hackle around its boundaries indicates that no decrease of stresses occurred during fracture, and fracture was possibly produced under a constant stress. Since AH is a material property, the fracture stress σfresponsible for a rapid fracture may be calculated following a determination of the mirror constant AH of the rock by σfrH½=AH

The creation and diffusion of a professional ideology in nineteenth century england

Abstract: The emergence of industrial society in England in the late eighteenth and early nineteenth centuries signalled the dissolution of traditional social relationships based on dependence and deference. The perceptions of reality and values of the ruling aristocracy lost their hegemony, as other classes began to develop competing ideological systems/ Each class tried to construct a vision of society in which it and its values were central. The traditional interpretations of this process recognize two main contenders for ideological dominance in nineteenth century England —the old landed aristocracy and the new entrepreneurial classes, with the working classes waiting in the wings for their chance. A fourth group, the professions, while never completely ignored, have usually been relegated to a rather peripheral position in this whole process of social and ideological competition. As a result, one scholar has recently called them the 'Forgotten Middle Qass'.^ They have not been entirely forgotten, but nevertheless the professions have rarely been recognized as constituting a distinct social class, with a unique identity and ideology. On i3ie contrary—the members of the professions have become type-cast in supporting roles as allies of the aristocracy, or of the business classes, or even of the working classes.' The portrayal of the nineteendi century precessions as no more than auxiliary social groups is perhaps a logical consequence of the difficulties encountered by scholars who have tried to identify, describe, and define these occupations. Sociologists have struggled unsuccessfully to isolate those diaracteristics wfaich distinguish the professions from other occupational groups.̂ The professions have continually defied attempts to locate diem within the context of traditional social categories.'̂ Professional men were respectable and even gentlemanly, but they worked for a living. They did not conform fully to the ideals

A Versatile Voltage Controlled Three Phase Oscillator

Abstract: A new method for constructing three phase analog oscillators is suggested and dealt with. The new method is essentially an extension into the three phase domain of methods known previously for the generation of sinewaves in two phases. An electronic realization of the method has resulted in a successful instrument whose performance is tested in the present paper.

The potential of ripening mutants for extending the storage life of the tomato fruit.

Abstract: The effect of the fruit ripening mutants rin, gr, nor and Nr on storage life and pigmentation was investigated in homozygous material, in heterozygous F1 combinations between the mutants with the colour mutant hp and with the normal cv. Kewalo. Crosses with nor showed a 3-to 5-fold increase in storage life in comparison with the normal cv. or with hp. Maximum pigmentation of the fruits of crosses with nor was pale-red with vineripened fruit and pink with fruit harvested at the breaker stage and ripened on the shelf. The ripening inhibitory effect of rin in the different F1 combinations was less pronounced than that of nor, and the colour of the fruits was improved. Fruits of the F1 cross between rin and nor showed greatly improved storage life and developed pink or pale red colour. Most heterozygotes with hp showed improved pigmentation. Problems anticipated in utilizing ripening mutants in breeding for improved keeping quality are discussed.

Myeloproliferative disorders terminating in acute micromegakaryoblastic leukaemia.

Abstract: Summary. Two cases of myeloproliferative disorder—one of myelofibrosis with agnogenic myeloid metaplasia and one of chronic granulocytic leukaemia terminating in acute micromegakaryoblastic leukaemia—are presented. The clinical course is described, and results are reported of morphological, cytometric, cytochemical and cytogenetic studies, as well as cell culture of blood cells in soft agar and in fluid medium.