Showing papers by "Bar-Ilan University published in 1971"
TL;DR: In this article, a detailed error analysis is presented showing that the over-all root-mean-square error in $a(q)$ never exceeds 2.5% for any value of the momentum transfer.
Abstract: Highly accurate x-ray diffraction measurements are presented for the static structure factor $a(q)$ for liquid Na (at 100 and 200 \ifmmode^\circ\else\textdegree\fi{}C) and liquid K (at 65 and 135 \ifmmode^\circ\else\textdegree\fi{}C). A detailed error analysis is presented showing that the over-all root-mean-square error in $a(q)$ never exceeds 2.5% for any value of the momentum transfer $q$ and the relative root-mean-square error in $a(q)$ between different temperatures is always less than 1.5%. We discuss and demonstrate the reliability of the tabulated values for the atomic form factor and the Compton-scattering correction. A brief discussion is included of the relative merits of x-ray vs neutron diffraction for obtaining the static structure factor.
244 citations
TL;DR: An improved direct spectrophotometric method is described that is suited to determinations of sulfide in enzyme mixtures and in biological materials and achieves major improvement in the method by quantitative precipitation of zinc sulfide and removal of the soluble components of the sample.
149 citations
TL;DR: The results lead to the conclusion that a low lipoxygenase activity may be due to the presence of antioxidants and definite conclusions cannot be drawn unless the enzyme is purified.
Abstract: SUMMARY The oxygen monitor was used in determining the linoleic acid oxidizing capacity of various plant tissues. Egg plant, potato, legume seeds, cauliflower and avocado contained considerable activity. The effects of nonionic detergents point to the presence of three types of lipoxygenase in the tissues tested. These are: (1) not affected by the detergent; (2) inhibited; and (3) either solubilized or stimulated by the detergent. Some tissues had considerable antioxidant activity as measured by their effect on commercial soybean lipoxygenase. These results lead to the conclusion that a low lipoxygenase activity may be due to the presence of antioxidants and definite conclusions cannot be drawn unless the enzyme is purified.
130 citations
TL;DR: In this paper, the authors compare enfants nes americains de families originaires d'Europe Orientale eleves dans la tradition juive a des enfs “purement” americains, de families anglo-axonnes e protestantes; les sujets sont [acaron]ges de 10 ans and sont equivalents du point de vue de l'intelligence and du milieu socio-economique.
Abstract: L'auteur teste l'hypothese scion laquelle l'appartenance a un sous-groupe dans un ensemble culturel influence le degre de differenciation psychologique. Il compare des enfants nes americains de families originaires d'Europe Orientale eleves dans la tradition juive a des enfants “purement” americains, de families anglosaxonnes e protestantes; les sujets sont [acaron]ges de 10 ans et sont equivalents du point de vue de l'intelligence et du milieu socio-economique. Un groupe d'enfants juifs, nettement plus “accultures”, a ete egalement etudie. Les resultats confirment l'hypothese: les enfants juifs (garcons) montrent proportionnellement moins de differenciation que les enfants anglo-saxons; ainsi le degre de differenciation psychologique refleterait le degre d' “acculturation”. Certains resultats permettraient de considerer que la differenciation psychologique est “multifacette”. L'auteur discute des implications des normes du WISC pour differentes sous-cultures.
62 citations
TL;DR: In this article, the authors present two proofs of an integral geometric formula concerning n-dimensional ellipsoids, based on a representation theorem for spherical functions due to Harish-Chandra.
Abstract: The paper presents two proofs of an integral geometric formula concerningn-dimensional ellipsoids. One of the proofs is based on a representation theorem for spherical functions due to Harish-Chandra.
27 citations
TL;DR: Investigation of intensive dispersal of sporangia of Pseudoperonospora cubensis (Berk & Curt.) Rostow from infected fields of cucumber in a hot, dry climate found that sporangial infectivity was reduced to nil only at 35 and 40°C, the highest temperatures tested.
Abstract: Intensive dispersal of sporangia of Pseudoperonospora cubensis (Berk & Curt.) Rostow from infected fields of cucumber in a hot, dry climate started between 06.00 and 07.00 h, reached a peak around 08.00 h, and subsided by noon. Infectivity of airborne sporangia to cucumber test plants diminished with high temperatures and high relative humidities during the interval between the time of dispersal and commencement of conditions favourable for infection. At the humidity levels tested during such an interval of 5 and 22 h, sporangial infectivity was reduced to nil only at 35 and 40°C, the highest temperatures tested. Infectivity of dispersed sporangia was greatly reduced when sporangia were wetted for a period too short to ensure infection and were then allowed to dry out. Most of the sporangia thus treated failed to release zoospores and this explained the decrease in their infectivity. Whether sporangia were dispersed by wind or by immediate contact with water did not alter the sensitivity of wetted sporangia to drying.
27 citations
TL;DR: It will follow that in order to deal adequately with induction, the authors must consider a factor which has usually not been taken into account, which can be said to correspond to an innate 'knowledge' which humans and animals have about the order, the regularity, of the world.
Abstract: There are a number of problems connected with induction which have not yet been satisfactorily resolved. In this paper, I shall discuss three of them and propose a solution. From our discussion it will follow that in order to deal adequately with induction, we must consider a factor which has usually not been taken into account. 1 Philosophically speaking, this factor can be said to correspond to an innate 'knowledge' which humans and animals have about the order, the regularity, of the world. The problems are: (1) The paradox of confirmation. (2) The low degree of confirmation which universal sentences usually obtain in inductive systems like that of Carnap (1950). (3) To define 'generally and rigorously' the difference between projectible and non-projectible predicates, i.e., between predicates that can be adequately used in inductive reasoning and those that cannot (Goodman, 1946, p. 383).
24 citations
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10 Mar 197118 citations
TL;DR: In tobacco pith culture, ABA promoted appearance of induced isoenzymes, the effect being completely checked by rifamycin, and GA3 promoted production of RNA in treated tobacco plants, suggesting effect on some preexisting RNA.
Abstract: By means of experimentation with the barley endosperm system and with peroxidase isoenzyme production during culture of tobacco pith the mode of action of abscisic acid (ABA) was investigated. Gibberellic acid (GA3) promoted reducing sugar production was significantly inhibited by ABA and bovine pancreas ribonuclease (RNase), while the specific RNA polymerase inhibitor rifamycin was without effect. In tobacco pith culture, ABA promoted appearance of induced isoenzymes, the effect being completely checked by rifamycin. Furthermore ABA significantly inhibited, and GA3 promoted production of RNA in treated tobacco plants. It is suggested that the mode of ABA action in these systems may be an inductive one on the degradative enzyme, RNase, and not necessarily a negative one on the promotive RNA polymerase. This conclusion implies effect on some preexisting RNA, the breakdown of which is mediated by ABA-activated RNase.
16 citations
01 Apr 1971
TL;DR: A full text retrieval system was designed for the responsa literature, which is a large corpus of Hebrew legal cases, and several methods were developed, among them "grammatical synthesis", which synthesizes all grammatical variants of a given keyword.
Abstract: A full text retrieval system was designed for the responsa literature, which is a large corpus of Hebrew legal cases. The unique problems of the data base --- mixture of Hebrew, Aramaic and vernaculars, lack of vowels and punctuation, extreme language inflection problems, homographs, existence of thousands of grammatical variants of any given keyword --- dictated development of new methods. Among them we list "grammatical synthesis", which synthesizes all grammatical variants of a given keyword; "Compact KWIC", which enables the user to have a glimpse of the nature of the search before having performed it; effective citation index imbedded in full text searches; and, in general, extensive use of both positive and negative feedback within a single search run. A number of searches performed on a relatively small data base gave in each case a recall of 100%. The average precision was 34%. A KWIC of strategic portions of retrieved documents usually enables a quick disposal of non-relevant material.
15 citations
TL;DR: The case of IBOLAND as discussed by the authors is a classic case study in the field of settlement geographies, and it has been studied extensively in the last few decades.
Abstract: (1971). DO WE HAVE A THEORY FOR SETTLEMENT GEOGRAPHY?—THE CASE OF IBOLAND. The Professional Geographer: Vol. 23, No. 3, pp. 197-203.
TL;DR: Isolierung zweier isomerer Vertreter der Flavongruppe aus Soyabohnenmehl: 6, 7, 4′Trihydroxyflavon aus frischem, Isoflavonglykosid aus gebrauntem material as mentioned in this paper.
Abstract: Isolierung zweier isomerer Vertreter der Flavongruppe aus Soyabohnenmehl: 6, 7, 4′Trihydroxyflavon aus frischem, Isoflavonglykosid aus gebrauntem Material.
TL;DR: The findings indicate that the respiratory wave comprises a superposition of two identical but inverse the one constituting a response to inspiration and the other to expiration.
Abstract: The respiratory modulation in the recordings of the arterial blood pressure and on the photoplethysmogram in the anesthetized cat, has been described so far as a uniform, periodic wave produced by one full cycle of breathing. The present study investigates the basic pattern of the respiratory wave which is obtained during artificial activation of the diaphragm of a cat by a rectangular stimulus to the phrenic nerves. The manner in which this artificial respiration was administered and the reason for its application are discussed. The findings indicate that the respiratory wave comprises a superposition of two identical but inverse the one constituting a response to inspiration and the other to expiration.
TL;DR: In this paper, a free-radical mechanism was proposed for the polymerization of acrylates and methacryls in methanol solution containing lithium acetate as electrolyte under currents ranging from 10 to 100 mA.
Abstract: Electrolytic polymerization of acrylates and methacrylates in methanol solution containing lithium acetate as electrolyte was investigated under currents ranging from 10 to 100 mA. Polymer yield increases up to a limiting current value, beyond which it decreases. This abnormal behavior is discussed. A free-radical mechanism is suggested.
TL;DR: The areal distribution of the mean minimum and maximum temperatures over Johannesburg in December 1966 and June 1967 are presented in this paper, where multiple regression analysis is used to determine the effects of topography and urban development on these distributions.
Abstract: The areal distribution of the mean minimum and maximum temperatures over Johannesburg in December 1966 and June 1967 are presented. Multiple regression analysis is used to determine the effects of topography and urban development on these distributions. Slope lapse rates in Johannesburg’s northern valleys are shown to reach 18°C/100 m on clear winter nights.
TL;DR: In this article, the nuclear resonant scattering of photons from several (n,γ) reactions, bounding nuclear levels in 141Pr were studied, and the results obtained in their de-excitation were presented.
TL;DR: In this paper, the temperature dependence near the α-β phase transition of the Raman spectra line widths of the two lowest A1 lines of crystalline quartz was studied.
TL;DR: The red-brown color obtained when peroxides react with ferrous ammonium thiocyanate permits identification and determination of lipoxygenase isoenzymes separated in cellulose acetate gel electrophoresis.
TL;DR: In this paper, the relationship between molecular weights and polymer yields as a function of current density, initial monomer concentration and dielectric constant of the solvent is described, and a kinetic scheme for the initiation, propagation, and termination is given.
Abstract: Methyl, ethyl, and n-butyl acrylates and methacrylates are polymerized by electroinitiation in methanol–, ethanol–, and n-propanol–electrolyte mixtures in which the monomers are soluble whereas the polymers obtained are insoluble. The technique of changing the polarity of the electrodes described earlier was used. The relationships between molecular weights and polymer yields as function of current density, initial monomer concentration and dielectric constant of the solvent are described. A kinetic scheme for the initiation, propagation, and termination is given.
TL;DR: In this article, it was demonstrated that by means of X-ray diffraction measurements in a transmission geometry, it is possible to determine very accurately the structure factor for liquid metals even in the low- q region.
TL;DR: In this article, the isomerization and dehydrogenation of terpinolene, (−)-limonene, α-terpinene over CaO was investigated at 290 and 380 °C.
TL;DR: The milk coagulating enzyme of Mucor pusillus compared to crude calf rennet was stimulated similarly by aluminium, ferric, calcium, and magnesium ions as discussed by the authors, suggesting two separate coagulation mechanisms.
TL;DR: In this article, the authors have studied the implementation of these principles in the classical teaching situation, that is, in the regular classroom as it has existed for many years and have found that this can be done through the question-andanswer method.
Abstract: Summary Recently, attempts to create a unified theory of learning have been made by psychologists, and one may try to approach practical problems via such a unified theory. We have adopted three principles from this theory: 1. Progress in small steps. 2. Active response. 3.Immediate confirmation and reinforcement. We have studied the implementation of these principles in the classical teaching situation, that is, in the regular classroom as it has existed for many years and have found that this can be done through the question‐and‐answer method. The mere fact that the entire lesson proceeds by way of questions and answers is not sufficient to ensure the three principles. Questions and answers alone do not yet constitute the question‐and‐answer method.To implement the three principles, the following additional rules must be adhered to: (a)The first principle requires that the questions split up the material into elements of knowledge (clauses) which lead in combination to a complete solution of our problem...
TL;DR: In this paper, a free-radical mechanism was proposed for the reaction and the relationship between molecular weight and monomer concentration, current densities, and time of the reaction as well as the yield as a function of current density, time of reaction and initial monomer concentrations were given.
Abstract: Ethyl methacrylate is polymerized by electroinitiation in methanol–electrolyte mixtures in which the monomer is soluble whereas the polymer obtained is insoluble. A technique of changing the polarity of the electrodes is used. With this technique a polymer of high molecular weight can be obtained. The relationships between molecular weight and monomer concentration, current densities, and time of the reaction as well as the yield as a function of current density, time of the reaction and initial monomer concentration are given. A free-radical mechanism is proposed for the reaction.
TL;DR: Acetylcholin erweiterte den Ast der Choroidarterie und vergrösserte stark das Abflussvolumen aus Ventrikeln und dem spinalen Subarachnoidalraum.
Abstract: Bei Perfusion der Liquorraume im Katzengehirn verschwindet Acetylcholin zu 90% aus dem Subarachnoidalraum, zu 60% aus den Ventrikeln. Eine fortlaufende Abnahme wurde im spinalen Subarachnoidalraum beobachtet. Acetylcholin erweiterte den Ast der Choroidarterie und vergrosserte stark das Abflussvolumen aus Ventrikeln und dem spinalen Subarachnoidalraum.
TL;DR: In this article, a Coulomb system with two time-retarded Green's functions is studied and a method of decoupling is proposed for obtaining collective effects and the thermodynamic potential.
Abstract: A Fermi system with Coulomb interactions is studied with two time-retarded Green’s functions. A method of decoupling is proposed for obtaining collective effects and the thermodynamic potential. The plasmon damping for low temperatures is calculated, as well as the momentum dependence of the occupation number in general and its discontinuity across the Fermi surface in particular.
TL;DR: The evidence accumulated is sufficient to establish that the ovaries of immature mice ‘devoid of corpora lutea’ are capable of converting exogenous pregnenolone to progesterone, and dehydroepiandrosterone to 4-androstenedione.
TL;DR: In the first stages of language acquisition, a child learns that the elements of a class C are named by the expression E by observing a few of these elements and noting that they are called E i...
Abstract: In the first stages of his language acquisition, a child learns that the elements of a class C are named by the expression E by observing a few of these elements and noting that they are called E i...