Showing papers by "Ben-Gurion University of the Negev published in 1978"
01 Jan 1978
181 citations
TL;DR: It is reported here that corticosteroids influence PG production by a mechanism involving RNA and protein synthesis, thus controlling the rate of synthesis of certain key proteins.
Abstract: THE finding that aspirin-like drugs act by inhibiting prostaglandin (PG) synthetase was reported by Vane et al.1, and the possible effects of anti-inflammatory steroids on PG production have since been a matter of controversy. Although some studies have indicated no appreciable effect of the corticosteroids on PG synthetase1–4, other investigators have presented evidence that corticosteroids may act by inhibiting the biosynthesis or release of PGs. The latter data were derived from studies on a variety of tissues such as skin5, adipose tissue4, inflamed synovia6,7, cultured fibroblasts8 and fibrosarcoma cells9. No satisfactory explanation for these controversial results has been offered, nor has the mechanism of this possible effect of corticosteroids on PG production been properly elucidated. The mechanism of action of the steroid hormones on their target organs has been clarified in recent years. These hormones are now thought to act primarily by stimulating transcription, thus controlling the rate of synthesis of certain key proteins (see ref. 10 for review). Many of the actions of the colt;rticosteroids on intermediary metabolism are indeed known to involve the induction of synthesis of specific enzyme proteins. We report here that corticosteroids influence PG production by a mechanism involving RNA and protein synthesis.
162 citations
TL;DR: In this article, a number of new conservation laws which make the solution process easier are presented, which can be used to obtain relativistic versions of the conservation of magnetic flux and of Kelvin's circulation theorem for an unmagnetized fluid, as well as a new flux conservation law for a charged fluid.
Abstract: The flow of magnetized plasma is governed by a large number of coupled equations (Maxwell's, Euler's, conservation of energy and of baryon number) so that the solution of a problem in general-relativistic magnetohydrodynamics is very complicated, even if symmetries are present. We present here a number of new conservation laws which make the solution process easier. We obtain the general criteria for a flux conservation law to exist. We apply them to obtain the relativistic versions of the conservation of magnetic flux and of Kelvin's circulation theorem for an unmagnetized fluid, as well as a new flux conservation law for a charged fluid. For stationary and axial symmetry we find conservation laws for each component of the Maxwell tensor; these are valid even if the plasma is nonperfect. For perfect plasma we find magnetic generalizations of the relativistic Bernoulli theorems for an unmagnetized fluid. We also find a new conservation law without previous analog. As an application of our results we show that extraction of rotational energy from a black hole by interaction with a magnetized plasma is not possible in the stationary state. This contradicts previous conclusions based on the approximation of geodesic flow. Finally, still for stationary and axial symmetry, we find the magnetic generalization of Kelvin's circulation theorem. With its help we reduce the problem of solving for the field of flow and for the magnetic field to the solution of two equations: baryon conservation and a Hamilton-Jacobi-type equation. A by-product of our derivations is an explicit formula for the strength of the magnetic field in terms of fluid variables.
115 citations
TL;DR: In this paper, the formation of magnesium hydride from pure activated magnesium and from some indium containing magnesium alloys has been studied and the experimental data fit the rate equation (1−2α/3)−(1−α)2/3] = Kt where α is the fraction of metal reacted at time t.
112 citations
TL;DR: Azoospermia was diagnosed in six factory workers who had been chronically exposed to 1,2-dibromo-3-chloropropane and selective atrophy of the germinal epithelium, intact Sertoli cells, and a normal appearance of a relatively increased number of Leydig cells were found.
102 citations
TL;DR: This work formulate VSP as a pure integer programming problem and provides an exact algorithm that examines a sequence of feasibility capacitated transportation problems with job splitting elimination side constraints and offers an approximate solution procedure based on the entropy principle of informational smoothing.
Abstract: We treat the following problem: There are n jobs with given processing times and an interval for each job's starting time. Each job must be processed, without interruption, on any one of an unlimited set of identical machines. A machine may process any job, but no more than one job at any point in time. We want to find the starting time of each job such that the number of machines required to process all jobs is minimal. In addition, the assignment of jobs to each machine must be found. If every job has a fixed starting time the interval is a point, the problem is well-known as a special case of Dilworth's problem. We term it the fixed job schedule problem FSP. When the job starting times are variable, the problem is referred to as the variable job schedule problem VSP, for which no known exact solution procedure exists. We introduce the problems by reviewing previous solution methods to Dilworth's problem. We offer an approximate solution procedure for solving VSP based on the entropy principle of informational smoothing. We then formulate VSP as a pure integer programming problem and provide an exact algorithm. This algorithm examines a sequence of feasibility capacitated transportation problems with job splitting elimination side constraints. Our computational experience demonstrates the utility of the entropy approach.
102 citations
TL;DR: Calliderived from the wild species grew better under salinity than those derived from the cultivated species, and accumulated more Cl − and Na + and less K + than the latter.
90 citations
TL;DR: The wild species Solanum pennellii accession Atico was found to be more salt tolerant than the cultivated tomato, although the growth of the wild species was not impaired by the high salinity.
Abstract: The cultivated tomato Lycopersicon esculentum, cultivar Rheinlands Ruhm, and the wild species Solanum pennellii accession Atico, were compared with respect to their salt tolerance The wild species was found to be more salt tolerant than the cultivated tomato In contrast to L esculentum plants, the growth of the wild species was not impaired by the high salinity (Table 1), although the latter accumulated more Cl− and Na+ ions and its K+ level decreased under salinity (Tables 3, 4, 5) The smaller increase in water deficit under salinity in the wild species, probably resulted from its higher accumulation of ions (Table 2)
86 citations
TL;DR: In this article, the authors deal with a model of duopoly pricing in the context of firms providing services to consumers and show that the Cournot-Nash equilibrium is such that the two firms charge in general different prices.
85 citations
TL;DR: In this paper, a long wave electromagnetic signal detection by glow-discharge plasma, based upon gas breakdown theory by high frequency electric fields, is developed to include internal signal amplification, upper and lower limits to response linearity, temporal and spectral response properties, and noise in the abnormal glow discharge.
Abstract: The mechanism of long wave electromagnetic signal detection by glow-discharge plasma, based upon gas breakdown theory by high frequency electric fields, is developed to include internal signal amplification of the order of that associated with the photomultiplier, upper and lower limits to response linearity, temporal and spectral response properties, and noise in the abnormal glow discharge. Agreement between signal-to-noise expressions in this analysis and measurements involving simple and inexpensive glow discharge indicator lamps exhibiting excellent sensitivity to microwave radiaion is quite good. An inherent ideal limit to speed of response is derived which indicates picosecond-order risetimes are theoretically possible if parasitic reactance effects which limit risetimes of present day devices to microsecond order can be overcome. Sensitivity can be improved further by increasing the number of free electrons. Enhanced diffusion current losses for a subnormal glow yield spectrally flat response which can be useful in radiometric applications.
77 citations
TL;DR: Jewish residents of Israel in 1960-72 with Hodgkin's disease and controls drawn from the general population showed a significant association between HD and parental consanguinity and pointed to the possible etiologic role of recessive inheritance.
Abstract: Jewish residents of Israel in 1960-72 with Hodgkin's disease (HD) were compared with controls drawn from the general population. The controls were individually matched by sex, age, origin, and date of immigration. The comparison showed a significant association between HD and parental consanguinity and pointed to the possible etiologic role of recessive inheritance. Females with HD tended to have a lower parity than did their controls. Associations between HD and a high educational level and the presence of a flush toilet in the childhood home were significant and gave limited support to the hypothesis that a high standard of living in childhood increases the risk of subsequent HD. Tonsillectomy and a history of work with wood or trees were significantly associated with mixed cellularity but not with other histologic subtypes. Differences between patients with HD and controls with respect to cigarette smoking, exposure to animals, marital status, previous blood transfusions or jaundice, contact with asbestos, residual or occupational mobility, or other characteristics were not significant.
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TL;DR: In this paper, the authors consider the infinite game between two players, Empty and Nonempty, and show that if ⋆n = 0xSn is empty then Empty wins, and if ↆn=0∞Sn is nonempty then Nonempty wins.
Abstract: Let us consider the following infinite game between two players, Empty and Nonempty. We are given a large set S. Empty opens the game by choosing a large subset S0 of S; then Nonempty chooses a large set S1 ⊆ S0; then Empty chooses large S2 ⊆ S, etc. The game is over after ω moves. If ⋂n=0xSn is empty then Empty wins, and if ⋂n=0∞Sn is nonempty then Nonempty wins.If “large” means “infinite”, then Empty can beat Nonempty rather easily: he chooses So countable, S0 = {a0, a1,…, an,…}, and then he chooses S2 such that a0 ∉ S2, S4 such that a1, ∉ S4 and so on.Next we assume that S is a set of uncountable cardinality, and that “large” means “of cardinality ∣S∣”. Then still Empty can win, but his winning strategy is somewhat more sophisticated: Let us identify S with a cardinal number κ. Thus each subset of S of size κ is a set of ordinals below κ. For each X ⊆ κ of size κ, let fx be the unique order-preserving mapping of X onto κ, and let F(X) = {x ϵ X: f(x) is a successor ordinal}. Empty's strategy is to play S0 = F(K), and when Nonempty plays S2k − 1, let S2k = F(S2k − 1).
TL;DR: In this paper, a clear PVC pond was placed within an insulated wooden container equipped with a hinged cover, which performed as a solar reflector during the day and was thermally insulated so as to enable the overnight storage of the heated water.
TL;DR: In this article, the background metric tensor is chosen on the basis of a model of the universe, in accordance with the perfect cosmological principle, it is taken as describing a space-time of constant curvature.
Abstract: In the bimetric theory of gravitation the background metric tensor γ
μν
, previously taken as describing flat space-time, is now chosen on the basis of a model of the universe. In accordance with the perfect cosmological principle, it is taken as describing a space-time of constant curvature. There are three possible forms, corresponding tok=0, 1, −1. Only fork=1 (a closed universe) does the model not go through a singular state; hence this is the appropriate choice. The isotropic solution of the field equations can be chosen to agree with the present cosmological observations. For small systems like the solar system the theory gives the same results as before, in agreement with those of general relativity.
TL;DR: Various models advanced to explain the relationship between cell dimensions and generation time are compared for rod-shaped bacteria growing under steady-state conditions and a more promising way of discriminating among the remaining models is suggested.
Patent•
15 Feb 1978TL;DR: In this paper, a method and apparatus for generating power utilizing reverse electrodialysis in which a concentrated ionic solution and a dilute ionic solutions are passed through two pathways in a reverse electrodes unit including a membrane stack, whereby solute from the concentrated solution passes through the membrane to the dilute solution accompanied by the generation of an output electrical current and voltage.
Abstract: A method and apparatus are described for generating power utilizing reverse electrodialysis in which a concentrated ionic solution and a dilute ionic solution are passed through two pathways in a reverse electrodialysis unit including a membrane stack, whereby solute from the concentrated solution passes through the membrane to the dilute solution accompanied by the generation of an output electrical current and voltage. The concentrated and dilute ionic solutions are regenerated by thermal separation from the solutions exiting from the unit and are recycled back through the unit.
TL;DR: A model for finding the maximum allowable allocation of seats on the various spans at each time prior to departure such that a maximum expected contribution to profit for the flight is obtained.
TL;DR: In this article, the authors measured the proton spin-lattice relaxation time of hydrogen in titanium hydride as a function of temperature and hydrogen concentration in the temperature range where the overriding relaxation mechanism is the interaction with the conduction electrons.
Abstract: The proton spin-lattice relaxation time ${T}_{1}$ of hydrogen in titanium hydride was measured as a function of temperature and hydrogen concentration in the temperature range where the overriding relaxation mechanism is the interaction with the conduction electrons. The hydrogen-concentration dependence and the temperature dependence of ${({T}_{1e}T)}^{\ensuremath{-}\frac{1}{2}}$ is presented. A break in the temperature dependence curve of ${({T}_{1e}T)}^{\ensuremath{-}\frac{1}{2}}$ was found for hydrogen concentrations having atomic ratios greater than 1.8. This is associated with a tetragonal deformation which is known to occur for the hydride. A phenomenological model of the electronic structure based on a semirigid band is proposed to explain the data. The concentration and temperature dependence of the susceptibility, hyperfine interactions, and transport properties are discussed in terms of the proposed model as well as the cause of the tetragonal deformation and the low-hydrogen-concentration limit of the hydride.
TL;DR: In this paper, it was shown that the rate of cell elongation or of envelope synthesis seems to increase abruptly at a particular age, and that hyphal density eventually begins to rise; when it reaches a critical value, new zones are formed.
Abstract: IN synchronous cultures of bacteria, the rate of cell elongation1 or of envelope synthesis2 seems to increase abruptly at a particular age. These and other findings suggest3–5 that bacterial envelope is formed at a constant rate, possibly by enzymes organised in zones, and that some event in the cell cycle leads to a discrete increase in the amount of enzymes or number of zones concerned. (The actual event involved has been variously identified with initiation of chromosome replication4, with termination1,5 and with the attainment of a critical cell length6.) Growth zones are known to occur in the filamentous fungi7. The rate at which these zones are able to add new envelope is limited, and since mass increases exponentially8, hyphal density eventually begins to rise; when it reaches a critical value, new zones are formed. Thus density (or indeed the concentration of any product synthesised exponentially9) could control the rate of surface growth, and we suggest that such is the case in bacteria.
TL;DR: The Aktivierungsenergie der Hydrierung von Mg wird durch einen Zusatz von unter 1 Atom-% Al, Ga oder In erheblich herabgesetzt, nimmt aber mit wachsendem Ubergangsmetallgehalt der Legierung bis etwa zu dem fur reines Mg geltenden Wert zu.
01 Jul 1978
TL;DR: In this paper, the simulation of a single fan component within an alluvial fan complex system is facilitated by observing contour offsets on topographic maps which indicate the position of the intersection point.
Abstract: Delimitation of a single fan component within an alluvial fan complex system is facilitated by observing contour offsets on topographic maps which indicate the position of the intersection point. Two different types of intersection points are discussed. Israeli topographic sheets of the Dead Sea area provide examples.
TL;DR: In this article, the universe of possible relationships among two predictors and a common criterion is analyzed following Conger's (1974) revised definition of suppressor variables, and a simple mapping of the possibl...
Abstract: Following Conger's (1974) revised definition of suppressor variables, the universe of possible relationships among two predictors and a common criterion is analyzed. A simple mapping of the possibl...
TL;DR: In this article, a finite element package is presented that is able to treat two-dimensional Schroedinger equation problems over a finite region with an arbitrary potential and homogeneous boundary conditions.
TL;DR: The mildly diminished overall left ventricular performance as shown by systolic time intervals appears to be related to the volume overload of the right ventricle and to the concomitantly diminished volume of the left ventricles rather than to any impairment of myocardial contractility.
Abstract: Eighteen patients with an atrial septal defect (Group I) and 45 patients whose defect had been repaired (Group II) were studied with echocardiography and systolic time Intervals. All patients In Group I had an increased right ventricular diameter (mean 24.5 mm/m2) that showed a direct linear relation to the size of the shunt (Qp/Qs ratio). In Group II the right ventricular diameter was significantly smaller (mean 15.6 mm/m2) (P < 0.001). The left ventricular diameter measured less than the mean normal value in 13 of the 18 patients in Group I (mean 23.2 mm/m2) and was significantly larger in the 45 in Group II (mean 27.7 mm/m2) (P < 0.001).
Comparison of systolic time intervals in Groups I and II showed that patients in the former group had shorter mean left ventricular ejection time index (LVETI) (407.9 versus 420.8 msec, P < 0.05), a longer mean preejection period index (PEPI) (140.9 versus 126.7 msec, P < 0.001) and a higher mean ratio of preejection period to ejection time (PEP/LVET) (0.39 versus 0.33, P < 0.001). A direct linear relation existed between both the preejection period index and the PEP/LVET ratio and the size of the shunt (Qp/Qs) in Group I. In three patients the abnormal systolic time intervals were consistent with mildly diminished left ventricular performance preoperatively but promptly returned to normal postoperatively. However, echocardiographic assessment revealed that left ventricular wall contractility was normal or hyperdynamic in all cases.
The mildly diminished overall left ventricular performance as shown by systolic time intervals appears to be related to the volume overload of the right ventricle and to the concomitantly diminished volume of the left ventricle rather than to any impairment of myocardial contractility. After closure of the defect the size of the ventricle and its performance return to normal.
TL;DR: The kinetics of nucleotide binding are strikingly altered upon activation of the protein as an ATPase, which suggests that activation involves lowering of the kinetic barriers to substrate and product binding-dissociation and has implications for the mechanism of energy transduction in photophosphorylation.
TL;DR: In this article, the authors present evidence that ABA can accumulate in the stomatal complex of Commelina communis L. The evidence is based on experiments involving the uptake, distribution and metabolism of exogenous 2-14C-ABA.
Abstract: THE plant hormone abscisic acid (ABA) is thought to be involved in the regulation of transpiration through its effects on stomatal aperture1. Application of synthetic ABA causes stomatal closure in whole plants2, shoots3 and leaf epidermal strips4. During water stress, levels of the hormone increase in plant tissues5, including the leaf epidermis6, and this is usually associated with stomatal closure7. There is evidence that ABA affects the ionic8,9 and metabolic9 status of the stomatal complex and it has been concluded that ABA acts directly on guard cells in effecting stomatal closure8,10,11. There is, however, little information about the distribution of ABA in specific cells of the epidermis or about the sensitivity of the stomatal complex to ABA. We present here evidence that ABA can accumulate in the stomatal complex of Commelina communis L., a species used extensively in studies of stomatal physiology12. The leaves of this plant yield relatively uncontaminated epidermal strips13 and this property has made it possible to calculate the apparent sensitivity of the stomatal complex to ABA. The evidence is based on experiments involving the uptake, distribution and metabolism of exogenous 2-14C-ABA.
TL;DR: Effects of exogenous hormonal treatments on these parameters, as well as on endogenous hormonal levels, provided further evidence for the interrelationships between hormones and for their roles in senescence.
Abstract: The objective of the present work was to describe the simultaneous changes in endogenous levels of cytokinins, abscisic acid, indoleacetic acid and ethylene in detached, senescing tobacco (Nicotiana rustica L.) leaves. These measurements were related to changes in chlorophyll contents, 14CO2 fixation and proline contents — three parameters which have been considered to reflect senescence. Effects of exogenous hormonal treatments on these parameters, as well as on endogenous hormonal levels, provided further evidence for the interrelationships between hormones and for their roles in senescence.
Starting with actively growing attached leaves and ending with well-advanced senescence in detached leaves, our data indicate a chronological sequence of three hormonal states: (a) cytokinins — high activity, abscisic acid, auxin and ethylene — low contents (actively growing, attached leaves); (b) cytokinins — low activity, abscisic acid — high, auxin and ethylene — low contents (apparent induction of senescence in detached leaves); and (c) cytokinins and abscisic acid — low, auxin and ethylene — high contents (senescence proper in detached leaves).
TL;DR: In this paper, the authors used neon in the pressure range 20-200 torr and achieved a working temperature of 1650 ± 50°C for the longitudinal copper vapor laser with an average power of 19.5 W with 0.7% efficiency.
TL;DR: In this article, a major pulse of andesitic volcanism lasting about 100 yr began in the Tongariro volcanic center at the southern end of the Taupo volcanic zone in North Island, New Zealand.
Abstract: About 9,800 yr ago a major pulse of andesitic volcanism lasting about 100 yr began in the Tongariro volcanic center at the southern end of the Taupo volcanic zone in North Island, New Zealand. Immediately following the onset of this intense period of andesitic volcanism, two voluminous rhyolitic eruptions from the Taupo volcanic center, located a few kilometres northeast of the Tongariro volcanic center, occurred after a period of quiescence of about 10,000 yr. The andesite volcanism marks a change in composition of titanomagnetite, which shows lower vanadium, chromium, cobalt, and nickel contents when compared with older andesites. Titanomagnetites analyzed from fresh rhyolite lapilli erupted from the Taupo volcanic center show a similar change in vanadium, nickel, and cobalt contents. Their composition falls into two distinct chemical groupings, which correspond to an older (about 9,800 to 8,850 yr) and younger (about 6,300 to 1,820 yr) rhyolitic Taupo magma previously distinguished on the basis of major-element glass chemistry and iron-titanium oxide equilibration temperatures. It is suggested that the timing of eruption of the andesite at about 9800 B.P. is related to that of the older Taupo rhyolitic magma, or that both were initiated by the same external trigger. Subsequent large-scale rhyolitic eruptions of the younger Taupo magma, however, showed no obvious temporal relationship to the later intermittent andesite activity.