Showing papers by "Bar-Ilan University published in 1984"
TL;DR: The total daily flux of photosynthetically fixed carbon in light- and shade-adapted phenotypes of the symbiotic coral, Stylophora pistillata, was quantified and the ‘growth rate’ method emerged as superior to the conventional in vitro and in vivo methods.
Abstract: The total daily flux of photosynthetically fixed carbon in light- and shade-adapted phenotypes of the symbiotic coral, Stylophora pistillata, was quantified. Light adapted corals fixed four times as much carbon and respired twice as much as shade corals. Specific growth rates of zooxanthellae in situ were estimated from average daily mitotic indices and from ammonium uptake rates (nitrate uptake or nitrate reductase activity could not be demonstrated). Specific growth rates were very low, demonstrating that of the total net carbon fixed daily, only a small fraction (less than 5%) goes into zooxanthellae cell growth. The balance of the net fixed carbon (more than 95%) is translocated to the host. New and conventional methods of measuring total daily translocation were compared. The `growth rate' method, which does not employ $^{14}$C, emerged as superior to the conventional in vitro and in vivo methods. The contribution of translocated carbon to animal maintenance respiration (CZAR) was 143% in light corals and 58% in shade corals. Thus, translocation in the former could supply not only the total daily carbon needed for respiration but also a fraction of the carbon needed for growth. Whereas light-adapted corals released only 6%, shade-adapted corals released almost half of their total fixed carbon as dissolved or particulate organic material. This much higher throughput of organic carbon may possibly benefit the heterotrophic microbial community in shade environments.
497 citations
371 citations
TL;DR: In this paper, the social cost of monopoly power encompasses the resources expended by individuals seeking to become the beneficiaries of monopoly rents, and the indirect approach of taking the observed value of monopoly rent as indicative of the unobserved value of resources expended in rent seeking is adopted in approaches to evaluation of the social costs of such activity.
Abstract: There is now quite general recognition that the social cost of monopoly power encompasses the resources expended by individuals seeking to become the beneficiaries of monopoly rents. However, since the activity of rent seeking is generally not observable, direct estimates of resources expended in quests to acquire monopoly power are usually impossible to come by.1 As a consequence, the indirect approach of taking the observed value of monopoly rents as indicative of the unobserved value of the resources expended in rent seeking is quite generally adopted in approaches to evaluation of the social cost of such activity.
257 citations
TL;DR: It is shown that light-adapted Stylophora pistillata can acquire all of their basal metabolic carbon through photosynthesis and translocation, but that shade- Adapted St Sylophora colonies growing in shade acquire slightly less than half.
Abstract: Photoadaptation by photosynthetic organisms to lowered light intensities occurs in part through changes in pigment concentrations and in characteristics of the photosynthetic response curve. We have characterized photoadaptive responses of light- and shade-adapted colonies of the reef coral Stylophora pistillata , which possesses symbiotic algae (zooxanthellae) and grows naturally under a variety of light intensities in the highly cavernous reefs of the Red Sea. Shade-adapted corals have significantly more chlorophyll per individual zooxanthella cell than light-adapted corals (2.98 compared to 12.97 pg chlorophyll a per cell), but not a significantly different number of cells per unit area (1.00 × 10 6 cells per square centimetre), with the result that the mass of chlorophyll per unit area is greater for shade-adapted corals than for light-adapted corals. Tissue nitrogen content per unit area is significantly lower ( p p > 0.05) in shade forms. These biomass characteristics are concomitant with a variety of functional responses to natural light intensities. Rate of photosynthesis at saturating light intensities is the same per unit area in both forms (20.2 µgO 2 cm -2 h -1 for shade specimens; 18.8 for light specimens); but it is significantly different when measured by amount of chlorophyll (1.6 µg O 2 (chl a ) -1 h -1 for shade specimens compared with 5.0 for light specimens). The initial slope of the P: I curve, α , is significantly higher for shade specimens by area (0.21 for shade corals compared with 0.12 for light corals), but significantly lower for shade specimens by amount of chlorophyll a (0.01 for specimens from shade compared to 0.04 for specimens growing in the light). I k (the point at which maximum production begins) is significantly lower for shade specimens (138 µmol m -2 s -1 for shade compared to 273 for light), and likewise I c (the compensation point at which net coral photosynthesis = 0) is also significantly less for shade specimens (30 µmol m -2 s -1 for shade compared to 141 for light). The average nocturnal respiration rate is significantly higher for specimens growing in the light (13.9 µg O 2 cm -2 h -1 for light specimens compared to 7.6 for shade specimens). Corals in intense sunlight respire at almost twice the rate of shade corals, probably in response to their higher total gross production. Owing to higher production rates and lower respiration rates, integrated P c (gross)/ R c (24 h) ratios are greater for shade-adapted specimens either in direct sunlight (1.76 P/R for shade specimens in the light compared to 1.10 for light specimens in the light), or in the shade (0.43 for shade specimens in the cave compared to 0.10 for light specimen in the cave). By using previously defined equations and biomass assumptions, it can be shown that light-adapted Stylophora pistillata can acquire all of their basal metabolic carbon through photosynthesis and translocation, but that shade-adapted Stylophora colonies growing in shade acquire slightly less than half. These results also show that if there were no photoadaptive response, shade-adapted specimens would acquire less than 4 % of their carbon from photosynthesis
243 citations
TL;DR: This paper investigates the complexity status of these problems on various sub-classes of perfect graphs, including comparability graphs, chordal graphs, bipartite graphs, split graphs, cographs and κ-trees, where the k-cluster problem is polynomial and the weighted and connected versions are studied.
234 citations
TL;DR: In this study, a new approach for the evaluation of brain energy metabolism in awake animals became possible as UV transmitting optical fibers became available and the brain was exposed to various physiological and pathological conditions which resulted in the increase or decrease in the level of NADH.
190 citations
TL;DR: In this paper, a review of recent developments in the theory and measurement of electron-electron scattering and its contribution to the electrical and thermal resistivities for different types of conducting materials, such as extremely impure metals, one-dimensional and two-dimensional conductors, the simple metals, transition metals, semimetals, organic conductors and the A15 compounds are reviewed.
Abstract: Recent developments are reviewed in the theory and measurement of electron-electron scattering and its contribution to the electrical and thermal resistivities for different types of conducting materials, such as extremely impure metals, one-dimensional and two-dimensional conductors, the simple metals, transition metals, semimetals, organic conductors and the A15 compounds. The discussion includes the following topics: quantum corrections to the Fermi-liquid theory of electron-electron scattering (EES) due to static disorder, the effect of the dimensionality of the system on EES, the measurement and the calculation of the EES contribution to the resistivity of metals, the observed sample dependence of EES for the simple metals, the effect of EES on electron-surface scattering for thin wires, the contribution of EES to the anomalous surface impedance and to the optical relaxation time and the effect of a magnetic field on EES. Comparison is made between theory and recent experimental data for eac...
172 citations
TL;DR: The results suggest that during the transition from low-to-high growth-irradiance levels chlorophyll a is diluted by cell division and is not actively degraded, similar to other planktonic diatom groups.
Abstract: The marine planktonic diatom Thalassiosira weisflogii was grown in turbidostat culture under both continuous and 12 hL: 12 hD illumination regimes in order to study the kinetics of adaptation to growth-irradiance levels. In both illumination regimes adaptation to a higher growth-irradiance level was accompanied by an increase in cell division rates and a decrease in chlorophyll a cell-1. The rates of adaptation for both processes, derived from first order kinetic analysis, equaled each other in each experiment. The results suggest that during the transition from low-to-high growth-irradiance levels chlorophyll a is diluted by cell division and is not actively degraded. Introduction of a light/dark cycle lowered the rate of adaptation. In transitions from high-to-low growth-irradiance levels there was a sharp drop in growth rates and a slow increase in chlorophyll a cell-1 under both continuous and intermittent illumination. In the 12 hL:12hD cycle there was a circadian rhythm in chlorophyll a cell-1, where cellular chlorophyll contents increased during the light cycle and decreased during the dark cycle. This circadian rhythm was distinctly different from light intensity adaptation. For kinetic analysis of light intensity adaptation in a 12 hL: 12 hD cycle, the circadian periodicity was separated from the light intensity response by subjecting the data to a Kaiser window optimization digital filter. Kinetic parameters for light-intensity adaptation were resolved from the filtered data. The kinetics of lightintensity adaptation of marine phytoplankton are discussed in relation to their spatial variations and time scales of mixing.
159 citations
TL;DR: The specific absorption coefficient for chlorophyll a (kc) was measured in zooxanthellae from light- and shade-adapted colonies of the hermatypic coral, Stylophora pistillata from the Red Sea, to compare the quantum yields of photosynthesis in these corals.
Abstract: The specific absorption coefficient for chlorophyll a (k$\_{\text{c}}$) was measured in zooxanthellae from light- and shade-adapted colonies of the hermatypic coral, Stylophora pistillata from the Red Sea These data, together with measurements of photosynthetic rates and irradiance, were used to compare the quantum yields of photosynthesis in these corals Quantum yields varied from 010 CO$\_{2}$ per quantum at low light to less than 0001 CO$_{2}$ per quantum at maximal irradiances Shade-adapted corals had higher pigment content, which allowed them to have twice as much light harvesting capability as light-adapted corals In all cases, however, the quantum yield of the light-adapted corals was higher by a factor of about 15
150 citations
TL;DR: Verbal, physiological and behavioral differences were obtained showing that focus upon both the pain and the learning task yielded the strongest pain reactions, while focus upon the learning alone yielded the lowest pain reaction, but the largest learning errors.
Abstract: Despite its importance in pain perception, there is a paucity of research investigating the influence of anxiety This study tested the proposition that anxiety can lead to the exacerbation of pain perception when the source of anxiety is related to the pain experience When the source is related to something else, anxiety may even reduce the reaction to pain Sources of anxiety were manipulated in the laboratory — anxiety related to pain and anxiety related to successful learning or the combination of anxiety related to both pain and learning Verbal, physiological and behavioral differences were obtained showing that focus upon both the pain and the learning task yielded the strongest pain reactions, while focus upon the learning alone yielded the lowest pain reaction, but the largest learning errors Focus upon pain was in-between The theoretical implications of these data were discussed
137 citations
TL;DR: Two different questionnaire formats based on the semantic differential scale used in comparative image studies of countries are found to have nearly equal reliability, but they are not equivalent.
Abstract: Two different questionnaire formats based on the semantic differential scale have been used in comparative image studies of countries. The authors test the reliability and validity of each format a...
TL;DR: For instance, the authors found that interindividual variation in the exponent of magnitude estimation functions largely reflects differences in the ways that subjects use numbers to describe loudness and that the sensory representations of loudness are fairly uniform, though probably not wholly uniform, among people with normal hearing.
Abstract: Parameters of the psychophysical function for loudness (a 1000-Hz tone) were assessed for individual subjects in three experiments: (a) binaural loudness summation, (b) temporal loudness summation, and (c) judgments of loudness intervals. The loudness scales that underlay the additive binaural summation closely approximated S. S. Stevens's (1956) sone scale but were nonlinearly related to the scales that underlay the subtractive interval judgments, the latter approximating Garner's (1954) lambda scale. Interindividual differences in temporal summation were unrelated to differences in scaling performance or in binaural summation. Although the exponents of magnitude-estimation functions and the exponents underlying interval judgments varied considerably from subject to subject, exponents computed on the basis of underlying binaural summation varied less. The results suggest that interindividual variation in the exponent of magnitude-estimation functions largely reflects differences in the ways that subjects use numbers to describe loudnesses and that the sensory representations of loudness are fairly uniform, though probably not wholly uniform, among people with normal hearing. The magnitude of individual variation in at least one measure of auditory intensity processing, namely, temporal summation, seems at least as great as the magnitude of the variation in the underlying loudness scale.
TL;DR: Subjects made magnitude estimations of moving stimuli produced by a 10 X 10 factorial design of distances and durations, and Plotting subjective velocity against physical velocity with either duration or distance as the parameter resulted in families of converging psychophysical power functions.
Abstract: Subjects made magnitude estimations of moving stimuli produced by a 10 X 10 factorial design of distances and durations. Both group and individual data obeyed the bilinear interaction prediction of a simple ratio model. The relation between perceived and actual velocity, as well as the psychophysical contingencies constructed from the marginal means of the design, could be described by a power function with an exponent of about 0.63 as a representative figure. Plotting subjective velocity against physical velocity with either duration or distance as the parameter resulted, respectively, in families of converging psychophysical power functions. Some implications of the results for velocity research, especially the usefulness of specifying the correct metric structure, are discussed.
TL;DR: In the parent MBA‐14 cell line the growth of monocytes seemed to depend upon stimulating factor(s) produced by the fibroblastoid cells, which may constitute part of the mechanism controlling the activity of the hematopoietic microenvironment.
Abstract: Continuous cell lines were derived from primary cultures of adherent bone marrow cells from SJL/J, BALB/c, C3H/eb, RF, and nude-ICR mice. All these lines readily assumed a pure fibroblastoid appearance with the exception of the BALB/c line (MBA-14), which retained both fibroblastoid and monocytoid cells. This particular line could promote the proliferation of myeloid progenitors (CFU-C) in short-term bone-marrow cultures. The two cell types that composed the MBA-14 cell line were successfully isolated and grown separately; the monocytes as the 14M and 14M1 cell lines and the fibroblastoid cells as the 14F clones. The latter were found to be preadipocytes and accumulated fat in the absence of added hydrocortisone, in medium supplemented with fetal calf serum. Growth of the monocyte lines (14M and 14M1) was dependent upon the mononuclear phagocyte stimulator CSF-1. In the parent MBA-14 cell line the growth of monocytes seemed to depend upon stimulating factor(s) produced by the fibroblastoid cells. The 14M1 monocytes were able to process and degrade antigen as efficiently as primary macrophages. Furthermore, processed antigen produced by 14M1 cells evoked proliferative response by antigen-primed lymph-node cells. In addition to these immunological functions the 14M1 cells were capable of modulating the colony-stimulating activity and degree of adipogenesis exhibited by the fibroblastoid cells. These interactions between monocytes and fibroblastoid cells may constitute part of the mechanism controlling the activity of the hematopoietic microenvironment.
TL;DR: In this paper, a mean-field model of a Heisenberg spin-glass with weak random anisotropy was solved, and it was shown that an Ising-like phase transition in a finite magnetic field $H$ occurs at ${T}_{c}(H) \ensuremath{-}A{H}^{\frac{2}{3}}$ in the limit of small $H$.
Abstract: A mean-field model of a Heisenberg spin-glass with weak random anisotropy is solved. It is shown that an Ising-like phase transition in a finite magnetic field $H$ occurs at ${T}_{c}(H)\ensuremath{\sim}{T}_{c}(0)\ensuremath{-}A{H}^{\frac{2}{3}}$ in the limit of small $H$. The crossover to an Ising behavior occurs when $\frac{D}{J}g{(\frac{\ensuremath{\mu}H}{J})}^{\frac{2}{3}}$, where $D$ and $J$ are the anisotropy and exchange coupling constants, respectively.
TL;DR: In this article, the authors present a method for the study of random walks on disordered systems, and apply it to the problem of diffusion on percolation clusters at criticality, based on the exact enumeration of all possible random walks of a certain size on a given cluster.
Abstract: We present a useful method for the study of random walks on disordered systems, and apply it to the problem of diffusion on percolation clusters at criticality. The method is based on the exact enumeration of all possible random walks of a certain size on a given cluster. In particular, we calculate the meansquare end-to-end distance, the probability of return to the origin, and a diffusion chemical exponent ${d}_{w}^{l}$ (that describes the chemical distance traveled by the random walker) as functions of the number of steps. Also we present for the first time data showing clearly the difference between the myopic and blind ants, and find much more rapid convergence for the blind ant.
TL;DR: Aplysia fasciata were observed in a number of environments, and mating as a male produced arousal, expressed as an increased likelihood to respond to food or to mate as amale, while passive animals mated as females.
TL;DR: In this paper, the growth of carp T-like cells has been found in supernatants of mitogen (PHA)- and alloantigen (MLR)-stimulated carp leukocyte cultures.
Abstract: Activity promoting the growth of carp T-like cells has been found in supernatants of mitogen (PHA)- and alloantigen (MLR)-stimulated carp leukocyte cultures. Activity level in culture supernatants was elevated by phorbol myristate acetate. Proliferation of carp T-like lymphoblasts was also promoted in the presence of Il-2-containing supernatants of mammalian origin. The significance of these findings is discussed.
TL;DR: In this paper, the notion of strong discontinuity is introduced into the theory of international labour migration, and it is suggested that inter-country wage differentials alone may fail to induce international migration at the level of the decision making entity.
Abstract: SUMMARY
In this exploratory paper, the notion of (strong) discontinuity is introduced into the theory of international labour migration. It is suggested that inter-country wage differentials alone may fail to induce international migration at the level of the decision making entity. However, three factors - risk aversion, relative deprivation and asymmetric information - in conjunction with these wage differentials, may account for international migration.
ZUSAMMENFASSUNG
In dieser vorbereitenden Untersuchung wird der Begriff einer (starken) Unterbrechung der Theorie der internationalen Arbeitswanderung eingefuhrt. Es wird vorgeschtagen, dass Lohnunterschiede zwischen verschiedenen Landern selbst allein konnten internationale Abwanderung auf der Ebene der entscheidungsmachenden Gruppe nicht herbeifuhren. Jedoch drei Faktoren - Risikoabneigung, relative Entbehrung und asymmetrische Auskunfte - mogen im Zusammenhang mit diesen Lohnunterschieden die internationale Wanderungsbewegung erklaren.
RESUME
Dans cette elude exploratoire, la notion de discontinuite (forte) est introduite dans la theorie de la migration internationale travail. II est suggere que les diffeientiels sala-riaux d'entre-pays ne peuvent pas ȩ eux seule induire au niveau de l'entite de decisions, une migration internationale. Cependant, trois facteurs - l'aversion de risque, la deprivation relative et l'asymmetrie de l'information en conjonction avec ces diffe-rentiels salariaux, peuvent expliquer la migration internationale.
TL;DR: Theorem 1.1 and Corollary 1.2 of this paper state the final solution to the problem of classifying groups of type (H) as mentioned in this paper, and they prove the following:
TL;DR: The formation of an enzyme-fatty acid radical complex which reacts with the plant pigment appears to be necessary for bleaching to occur, and a scheme for the anaerobic bleaching of plant pigments during the lipoxygenase-catalyzed reaction is proposed.
TL;DR: It is suggested that while the PHA and ConA responsive cells may belong to the same lymphocyte subpopulation, they are distinct from the LPS-responsive subpopulation.
Abstract: Peripheral blood leukocytes (PBL) of carp respond in vitro to a variety of phytomitogens, shown to be T-cell specific or B-cell specific in mammalian systems. Some basic differences have been observed in the proliferative response of carp PBL to PHA (phytohemagglutinin), ConA (concanavalin A) and LPS (lipopolysaccharide): (1) The response to PHA and ConA was found to be highly dependent upon the continuous presence of mitogen in the medium, in contrast to LPS, where after the initial stimulation, cells could continue to proliferate for several days without mitogen. (2) Lymphoblasts grown in long term culture with either PHA or Con A could be transferred into medium containing the other mitogen without impairing cell proliferation, but cell growth was reduced to background level following transfer into LPS-containing medium. LPS grown cells continue to proliferate independently of the mitogen content of the medium. (3) Co-stimulation with LPS+PHA or LPS+ConA results in a synergistic response, while constimulation with PHA+ConA results in inhibition of DNA synthesis. (4) Several morphological differences have been observed between cells proliferating in the presence of PHA and those proliferating in the presence of LPS. It is suggested that while the PHA and ConA responsive cells may belong to the same lymphocyte subpopulation, they are distinct from the LPS-responsive subpopulation.
TL;DR: In this paper, the authors formulated and estimated a model designed to explain the allocation of intergovernmental grants to local authorities in Israel, taking into consideration the fact that this process is governed by mixed motivations associated with both the desire to adopt policies and actions based on the concept of public interest and with the desire for re-election.
Abstract: The empirical study and modelling of processes and motivations behind government behavior has been relatively meager. This paper has formulated and estimated a model designed to explain the allocation of intergovernmental grants to local authorities. The model takes into consideration the fact that this process is governed by mixed motivations associated with both the desire to adopt policies and actions based on the concept of public interest and with the desire for re-election. The model was applied to data pertaining to 52 local authorities in Israel under two governments. The principal findings of the foregoing analysis can be summarized as follows. First, the behavioral mechanism operating beyond intergovernmental grants allocation is inherent in the political system and equally applies to the two governments. Second, this mechanism is governed both by factors representing objective criteria describing the needs of the populations and by political factors representing the desire for re-election. Differences in the behavior of the two governments seem to be significant as far as some objective variables are concerned, but are almost insignificant as far as the political variable is concerned. Third, as in other studies conducted in the U.S., our findings support the hypothesis that in their attempt to maximize the prospects for re-election, governments find it preferable to pursue policies which reward their supporters rather than ‘buy-off’ their opponents. Lastly, by allowing per-capita grants to be a non-monotonous function of the political variable, it was found that indeed both governments have increased per-capita grants as a function of POL up to a certain level and decreased it thereafter.
TL;DR: In this paper, the authors provide a formal justification for qualified majority rules, in which individual preferences are identical but actual judgments may differ, special majority rules emerge as decision rules that maximize the probability of making correct decisions.
Abstract: This essay provides a formal justification for qualified majority rules. Specifically, within an uncertain dichotomous choice framework, in which individual preferences are identical but actual judgments may differ, special majority rules emerge as decision rules that maximize the probability of making correct decisions. The main result specifies the optimal special majority as a function of a priori bias in favor of the status quo, ability, and size of the decision-making body. The analysis of the relationships among these three variables in generating certain common qualified majority rules is then pursued.
TL;DR: Klein et al. as mentioned in this paper found that mothers' perceptions of their infants' temperament were differently related to their behavior toward boys as compared with girls, that is, intensity ratings were related to auditory stimulation and contingent positive vocalization for girls, and to increased physical contact for boys.
Abstract: KLEIN, PNINA S. Behavior of Israeli Mothers toward Infants in Relation to Infants' Perceived Temperament. CHILD DEVELOPMENT, 1984, 55, 1212-1218. The present study focused on the relations between mothers' perception of infants' temperament at 6 months and their behavior toward their infants at 6 and 12 months of age. Subjects were 40 firstborn Israeli infants, 21 boys and 19 girls. Carey's Infant Temperament Questionnaire (ITQ) was used for the evaluation of infants' perceived temperament, and Yarrow's time sampling technique was used for home observations of mothers' behavior. Infants rated as more adaptable, approaching, intense in response, and positive in mood received more sensory and social stimulation at the 6and the 12-month observations. Whereas no main effects for sex were found in the analysis of the observed maternal behavior, mothers' perceptions of their infants' temperament were differently related to their behavior toward boys as compared with girls, that is, intensity ratings were related to auditory stimulation and contingent positive vocalization for girls, and to increased physical contact for boys.
TL;DR: In this paper, the formation of α-tocopherol-lipoxygenase complex was elucidated using immobilized affinity purified soybean lipoxygenases and [ d - 3 H]α-toc-opherol.
TL;DR: Two-way and one-way mixed leukocyte reaction (MLR) was demonstrated in peripheral blood leukocytes (PBL) of carp, suggesting the usefulness of this method for genetic analysis of MLR-recognized histocompatibility antigens in carp.
Abstract: Two-way and one-way mixed leukocyte reaction (MLR) was demonstrated in peripheral blood leukocytes (PBL) of carp Primary two-way MLR in randomly selected donor pairs were highly variable Weak primary responses could be strongly augmented by mutual in vivo priming of the reacting donors One-way MLR was performed using irradiated (16,000 R) allogeneic PBL as stimulators Reciprocal responses of randomly paired donors were usually unequal, suggesting the usefulness of this method for genetic analysis of MLR-recognized histocompatibility antigens in carp Kinetics of the primary and secondary two-way MLR were studied, as well as the kinetics of primary one-way MLR against pooled allogenic stimulator cells