Showing papers by "Tel Aviv University published in 1988"
TL;DR: It is found that the usual measuring procedure for preselected and postselected ensembles of quantum systems gives unusual results and under some natural conditions of weakness of the measurement, its result consistently defines a new kind of value for a quantum variable, which is called the weak value.
Abstract: We have found that the usual measuring procedure for preselected and postselected ensembles of quantum systems gives unusual results. Under some natural conditions of weakness of the measurement, its result consistently defines a new kind of value for a quantum variable, which we call the weak value. A description of the measurement of the weak value of a component of a spin for an ensemble of preselected and postselected spin-(1/2 particles is presented.
2,224 citations
TL;DR: In this article, the authors explore the determinants of corporate takeover methods and their outcomes and price effects and focus on the effect of leverage on the takeover method and outcome and obtain several other results on price effects.
771 citations
TL;DR: In this article, the authors derive conditions under which the simple majority voting rule for electing controlling management and one share-one vote constitute a socially optimal corporate governance rule and show that other majority rules and/or multiple classes of shares are not socially optimal.
720 citations
TL;DR: The analysis of referring expressions can be divided into two branches for our purposes as discussed by the authors : theories of definite descriptions and proper names, and theories of presupposition: existence and/or uniqueness.
Abstract: The analysis of referring expressions can be divided into two branches for our purposes. The first includes theories of definite descriptions and proper names. The key to the riddle of the appropriate use of such expressions, it was thought, is the notion of presupposition: existence and/or uniqueness. Indeed, this was the question that dominated the literature for many years, starting with the early philosophical analyses of Frege (1982), Russell (1919) and Strawson (1956, 1964), and ending with the much later pragmatically oriented linguistic analyses, such as Liberman (1973), Kempson (1975), Prince (1978, 1981b), Gazdar (1979), McCawley (1979), Hawkins (1974, 1984) and even Loftus (1972, 1974, 1975), although this last approach is more psychological. The second branch of research totally neglected the question of presupposition. Non-syntactic/semantic theories of anaphoric expressions, pronouns especially, were psychologically oriented, and hence saw the issue to be accounted for quite differently. In fact, the objective of these theories has been to elucidate processing procedures by examining anaphoric expressions, rather than to make claims about anaphoric expressions as such.
531 citations
TL;DR: It is shown that determining whether s(G) ≤ K, for a given integer K, is NP-hard for general graphs but can be solved in linear time for trees.
Abstract: T. Parsons originally proposed and studied the following pursuit-evasion problem on graphs: Members of a team of searchers traverse the edges of a graph G in pursuit of a fugitive, who moves along the edges of the graph with complete knowledge of the locations of the pursuers. What is the smallest number s(G) of searchers that will suffice for guaranteeing capture of the fugitive? It is shown that determining whether s(G) ≤ K, for a given integer K, is NP-complete for general graphs but can be solved in linear time for trees. We also provide a structural characterization of those graphs G with s(G) ≤ K for K = 1, 2, 3.
412 citations
TL;DR: In this article, the Boltzmann superposition principle based on the general standard linear solid rheology is implemented in the equation of motion by the introduction of memory variables, and the propagation in time is done by a direct expansion of the evolution operator by a Chebycheff polynomial series.
Abstract: SUMMARY A new approach for viscoacoustic wave propagation is developed. The Boltzmann’s superposition principle based on the general standard linear solid rheology is implemented in the equation of motion by the introduction of memory variables. This approach replaces the conventional convolutional rheological relation, and thus the complete time history of the material is no longer required, and the equations of motion become a coupled first-order linear system in time. The propagation in time is done by a direct expansion of the evolution operator by a Chebycheff polynomial series. The resulting method is highly accurate and effects such as the numerical dispersion often encountered in time-stepping methods are avoided. The numerical algorithm is tested in the problem of wave propagation in a homogeneous viscoacoustic medium. For this purpose the l-D and 2-D viscoacoustic analytical solutions were derived using the correspondence principle.
381 citations
TL;DR: Sarafotoxins, a group of 21-residue cardiotoxic peptides from snake venom that induce coronary vasoconstriction, show high-affinity binding to rat atrial and brain membranes and activate the hydrolysis of phosphoinositide phosphodiesterase system.
Abstract: Sarafotoxins, a group of 21-residue cardiotoxic peptides from snake venom that induce coronary vasoconstriction, show high-affinity binding to rat atrial and brain membranes and activate the hydrolysis of phosphoinositides. Neither their binding nor their activity is affected by blockers or activators of known receptors and ion channels, suggesting that sarafotoxins act either directly on the phosphoinositide phosphodiesterase system or on a novel receptor. Their amino acid sequence shows a high degree of homology with that of endothelin, a recently described 21-residue vasoconstrictor peptide found in porcine aortic endothelium. This is remarkable, since endothelin is a natural compound of the mammalian vascular system while sarafotoxins are highly toxic components of snake venom.
353 citations
TL;DR: Opsonophagocytosis can occur in three modes: in the first modes, only antibodies participate by reacting via their (Fab)2 combining sites with the appropriate antigenic determinants on the bacterial surface, and in the second mode, only the C3b or C3bi fragment of complement participates.
Abstract: serum factors enhance the rate of uptake of microorganisms by phagocytes. The serum factors were named opsonins (from opsonos, to eat, in Greek), and the process became known as opsonophagocytosis. Over the years it has been established that the primary role of the opsonins is to provide a means of recognition between the phagocytes and their targets, e.g., bacteria (26, 38). The opsonins function by binding specifically in a lock-and-key manner to integral surface membrane molecules on the phagocytes on the one hand and to the bacteria on the other. Two types of opsonin have been described: one is represented by the C3b and C3bi fragments of the third component of complement (C3), and the other is represented by antimicrobial antibodies (usually immunoglobulin G molecules). Opsonophagocytosis can occur in three modes. In the first, only antibodies participate by reacting via their (Fab)2 combining sites with the appropriate antigenic determinants on the bacterial surface. The Fc portion of the coating immunoglobulin G molecule binds the microorganisms to the corresponding Fc receptors on the surfaces of the phagocytes. In the second mode, only the C3b or C3bi fragment of complement participates. The C3b and C3bi fragments are generated from C3 as a result of its activation by contact with certain microbial surface constituents, a process known
315 citations
311 citations
TL;DR: Three experiments investigated the effects of acute amphetamine administration on LI in rats and showed that the abolition of LI was obtained when the preexposure and conditioning were given 24 hr apart but not when the two stages were given in one session.
Abstract: In the latent inhibition (LI) paradigm, nonreinforced preexposure to a stimulus retards subsequent conditioning to that stimulus. Three experiments investigated the effects of acute amphetamine administration on LI in rats. Experiments 1 and 3 used a conditioned emotional response (CER) procedure and Experiment 2 used two-way active avoidance procedure. Experiments 1 and 2 showed that, in both the CER and avoidance procedures, 1.5 mg/kg dl-amphetamine administered either in the preexposure or the conditioning stage alone did not disrupt LI. In contrast, amphetamine administered in both of the stages abolished LI. Experiment 3 showed that the abolition of LI was obtained when the preexposure and conditioning were given 24 hr apart but not when the two stages were given in one session.
293 citations
TL;DR: The present investigation was undertaken to verify that bone-like features were identifiable at the ultrastructural level and electron microprobe and electron and X-ray diffraction analysis confirmed the mineral to be hydroxyapatite.
TL;DR: In this paper, a Differential Scheme (DS) approximation for elastic properties of cracked materials is established by a limiting process on the basis of the DS for porous materials, which is applied to obtain stiffness reduction due to randomly oriented elliptical and penny-shaped crack distributions in isotropic matrix, and to the case of aligned plane cracks in orthotropic sheets.
Abstract: A Differential Scheme (DS) approximation for elastic properties of cracked materials is established by a limiting process on the basis of the DS for porous materials. The method is applied to obtain stiffness reduction due to randomly oriented elliptical and penny-shaped crack distributions in isotropic matrix, and to the case of aligned plane cracks in orthotropic sheets.
TL;DR: It is shown that twisted nematic liquid-crystal spatial light modulators behave as phase-only modulators when operated below the conventional optical threshold and behave as spatial amplitude modulator when used between crossed polarizers above the optical threshold.
Abstract: It is shown that twisted nematic liquid-crystal spatial light modulators behave as phase-only modulators when operated below the conventional optical threshold. Thus such devices, when operated in a reflection mode, behave as spatial amplitude modulators when used between crossed polarizers above the optical threshold; they behave as phase modulators when used between parallel polarizers and operated below that threshold.
TL;DR: In this article, an integrative model is proposed that posits that raising expectations and setting difficult goals are mutually reinforcing means that can boost productivity and that measuring expectancy as subjective probability of success has impeded expectancy research Comparative quantiles and amount of output expected are proposed as alternatives to SPS.
Abstract: The Pygmalion, goal-setting, and need-for-achievement approaches use effort-to-performance expectancy in order to explain work motivation. The motivation to expend effort is distinguished from the motivation to choose a task. Expectancy is conceptualized both as a stable trait and as a changing state. A resolution of rival hypotheses derived from expectancy theory and the theory of achievement motivation is proposed. An integrative model posits that raising expectations and setting difficult goals are mutually reinforcing means that can boost productivity. It is argued that measuring expectancy as subjective probability of success (SPS) has impeded expectancy research Comparative quantiles and amount of output expected are proposed as alternatives to SPS.
01 Jan 1988
TL;DR: An eigenstructure-based method for direction finding in the presence of sensor mutual coupling, gain and phase uncertainties is presented and its behaviour is illustrated by a numerical example.
Abstract: An eigenstructure-based method for direction finding in the presence of sensor mutual coupling, gain and phase uncertainties is presented. The method provides estimates of the directions of arrival of all the radiating sources as well as calibration of the gain and phase of each sensor and the mutual coupling in the receiving array. Calibration sources at known locations are not required. The proposed algorithm is described in detail, and its behaviour is illustrated by a numerical example.
TL;DR: In this paper, an approximate general method for calculating the effective dielectric function of a random composite in which there is a weakly nonlinear relation between electric displacement and electric field was proposed.
Abstract: We propose an approximate general method for calculating the effective dielectric function of a random composite in which there is a weakly nonlinear relation between electric displacement and electric field of the form $\mathbf{D}=\ensuremath{\epsilon}\mathbf{E}+\ensuremath{\chi}{|\mathbf{E}|}^{2}\mathbf{E}$, where $\ensuremath{\epsilon}$ and $\ensuremath{\chi}$ are position dependent. In a two-phase composite, to first order in the nonlinear coefficients ${\ensuremath{\chi}}_{1}$ and ${\ensuremath{\chi}}_{2}$, the effective nonlinear dielectric susceptibility is found to be ${\ensuremath{\chi}}_{e}=\ensuremath{\Sigma}{i=1,2}^{}(\frac{{\ensuremath{\chi}}_{i}}{{p}_{i}}){(\frac{\ensuremath{\partial}{\ensuremath{\epsilon}}_{e}}{\ensuremath{\partial}{\ensuremath{\epsilon}}_{i}})}_{0}{|\frac{\ensuremath{\partial}{\ensuremath{\epsilon}}_{e}}{\ensuremath{\partial}{\ensuremath{\epsilon}}_{i}}|}_{0}$, where ${\ensuremath{\epsilon}}_{e}^{(0)}$ is the effective dielectric constant in the linear limit (${\ensuremath{\chi}}_{i}=0,i=1,2$) and ${\ensuremath{\epsilon}}_{i}$ and ${p}_{i}$ are the dielectric function and volume fraction of the ith component. The approximation is applied to a calculation of ${\ensuremath{\chi}}_{e}$ in the Maxwell-Garnett approximation (MGA) and the effective-medium approximation. For low concentrations of nonlinear inclusions in a linear host medium, our MGA reduces to the results of Stroud and Hui. An exact calculation of ${\ensuremath{\chi}}_{e}$ is carried out for the Hashin-Shtrikman microgeometry and compared to our MG approximation.
TL;DR: A general class of Bayesian lower bounds on moments of the error in parameter estimation is formulated, and it is shown that the Cramer-Rao, the Bhattacharyya, the Bobrovsky-Zakai, and the Weiss-Weinstein lower bounds are special cases in the class.
Abstract: A general class of Bayesian lower bounds on moments of the error in parameter estimation is formulated, and it is shown that the Cramer-Rao, the Bhattacharyya, the Bobrovsky-Zakai, and the Weiss-Weinstein lower bounds are special cases in the class. The bounds can be applied to the estimation of vector parameters and any given function of the parameters. The extension of these bounds to multiple parameter is discussed. >
TL;DR: In this paper, the authors explored the origins of the unidirectionality of electron transfer between the excited singlet state of the bacteriochlorophyll dimer and the bacteriopheophytin (H) along the L protein subunit.
TL;DR: In this paper, the authors document a seasonal pattern in stock returns around quarterly earnings announcement dates: small firms show large positive abnormal returns and a sizable increase in the variability of returns around these dates.
TL;DR: A new technique for proving lower bounds in the synchronous model is presented, based on a string-producing mechanism from formal language theory, first introduced by Thue to study square-free words.
Abstract: The computational capabilities of a system of n indistinguishable (anonymous) processors arranged on a ring in the synchronous and asynchronous models of distributed computation are analyzed. A precise characterization of the functions that can be computed in this setting is given. It is shown that any of these functions can be computed in O(n2) messages in the asynchronous model. This is also proved to be a lower bound for such elementary functions as AND, SUM, and Orientation. In the synchronous model any computable function can be computed in O(n log n) messages. A ring can be oriented and start synchronized within the same bounds.The main contribution of this paper is a new technique for proving lower bounds in the synchronous model. With this technique tight lower bounds of t(n log n) (for particular n) are proved for XOR, SUM, Orientation, and Start Synchronization. The technique is based on a string-producing mechanism from formal language theory, first introduced by Thue to study square-free words. Two methods for generalizing the synchronous lower bounds to arbitrary ring sizes are presented.
01 Jan 1988
TL;DR: In this article, an asymptotic nonlinear integrodifferential equation for spontaneous instability of the plane front of a laminar flame is derived, and it is shown that in all cases spontaneous instability implies an increase in its propagation velocity.
Abstract: An asymptotic nonlinear integrodifferential equation is derived for spontaneous instability of the plane front of a laminar flame.
If the combustible mixture is deficient in the light component, spontaneous instability will lead to self-turbulization of the flame, and the flame front assumes a strongly nonstationary cellular structure.
If there is an excess of the light component, spontaneous instability produces stationary, irregular wrinkles on the flame front, and the flame continues to propagate in a laminar regime.
It is shown that in all cases spontaneous instability of the flame implies an increase in its propagation velocity.
TL;DR: This chapter presents a new concept concerning the mode of cellulose degradation, and the cellulosome concept can be considered to encompass the general organization of various complementary cellulases and related components into defined complexes, which may form larger polycellulosoma structures.
Abstract: Publisher Summary The accelerated interest in microbial cellulases stems from their potential industrial application. This area is an excellent example in which basic and applied science are closely interlinked: the better understood the mechanism of cellulase action; the better can be the applicative value as a biotechnological process. This chapter presents a new concept concerning the mode of cellulose degradation. In this mode, the model organism, the cellulosome is anchored to the cell surface in polycellulosomal centers, which also mediate the adherence of the bacterium to the insoluble substrate. Moreover, the cellulosome concept can be considered to encompass the general organization of various complementary cellulases and related components into defined complexes, which may form larger polycellulosoma structures. Finally, the cellulosome concept may bear particular relevance to other microbial systems wherein other structurally complex insoluble polymers (for example, starch, chitin, and various insoluble proteinaceous matrices) are degraded enzymatically.
TL;DR: A meta-analysis of experimental investigations of the effects of applicant gender (1842 subjects across 19 studies) and qualifications (1767 subjects across 20 studies) on hiring recommendations was conducted by as mentioned in this paper.
01 Aug 1988
TL;DR: This work presents an algorithm for finding all occurrences of the pattern in the text, each with at most k differences, given a text of length n, a pattern of length m, and an integer k.
Abstract: Consider the string matching problem where differences between characters of the pattern and characters of the text are allowed. Each difference is due to either a mismatch between a character of the text and a character of the pattern or a superfluous character in the text or a superfluous character in the pattern. Given a text of length n , a pattern of length m , and an integer k , we present an algorithm for finding all occurrences of the pattern in the text, each with at most k differences. It runs in O ( m + nk 2 ) time for an alphabet whose size is fixed. For general input the algorithm requires O ( m log m + nk 2 ) time. In both cases the space requirement is O ( m ).
TL;DR: In this article, the authors examined the ethical beliefs and behavior of a sample of Israeli managers (n=97) and comparable data from the United States, concluding that the best predictor of respondents' ethical behavior is their beliefs and perceptions concerning their peers' behavior.
Abstract: This study examines the ethical beliefs and behavior of a sample of Israeli managers (n=97) and comparable data from the United States. Israeli managers rated themselves both highly ethical and more ethical than their peers. These results are similar to those found for the U.S., and indicate that the best predictor of respondents' ethical behavior is their beliefs and perceptions concerning their peers' behavior. In addition, this study examines the managers' predisposition to promote social responsibility by joining social networks of managers and other business people, established for that purpose. Seventy-eight percent are of the opinion that networks for the promotion of social responsibility in business are needed and 57% are ready to join them.
TL;DR: Variations of the boxplot are suggested, in which the sides of the boxes are used to convey information about the density of the values in a batch, in a way designed to keep their ease of computation by computer.
Abstract: Variations of the boxplot are suggested, in which the sides of the box are used to convey information about the density of the values in a batch. The ease of computation by hand of the original boxplot had to be sacrificed, as the variations are computer-intensive. Still, the plots were implemented on a desktop personal computer (Apple Macintosh), in a way designed to keep their ease of computation by computer. The result is a dynamic display of densities and summaries.
TL;DR: The orbital magnetoconductance in the variable-range--hopping (VRH) regime is evaluated by use, for definiteness, of a model proposed by Nguyen, Spivak, and Shklovskii, which approximately takes into account the interference among random paths in the hopping process.
Abstract: The orbital magnetoconductance (MC) in the variable-range--hopping (VRH) regime is evaluated by use, for definiteness, of a model proposed by Nguyen, Spivak, and Shklovskii, which approximately takes into account the interference among random paths in the hopping process. Instead of logarithmic averaging which is shown to be inadequate for this case, the MC is obtained by the critical percolating resistor method of Ambegaokar, Halperin, and Langer. The small-field MC is quadratic in H; it is positive deep in the VRH regime and changes sign when the zero-field conductivity is high enough. This behavior (except for the sign change) and the relevant magnetic field scale are in agreement with recent experiments. The calculated MC is always positive for strong fields and is predicted to saturate at sufficiently large fields.
TL;DR: In 1:1 gas:(water vapor) mixtures, the competition among these gases on the available sites in the ice showed that the trapping capacity for the various gases is determined not only by the structure and dynamics of the ice, but is also influenced by the gas itself.
Abstract: Our studies on gas trapping in amorphous water ice at 24-100 K were extended, by using mixtures of CH4, CO, N2, and Ar, rather than single gases. In 1:1 gas:(water vapor) mixtures, the competition among these gases on the available sites in the ice showed that the trapping capacity for the various gases is determined not only by the structure and dynamics of the ice, but is also influenced by the gas itself. Whereas at 24-35 K all four gases are trapped in the ice indiscriminantly, at 50-75 K there is a clear enhancement, in the order of CH4 > CO > N2 > or approximately Ar. This order is influenced by the gas-water interaction energy, the size of the trapped gas atom or molecule, the type of clathrate-hydrate formed (I or II) and, possibly, other factors. It seems that the gas can be trapped in the amorphous ice in several different locations, each being affected in a different way by the deposition temperature and gas composition. Once a gas atom or molecule is trapped in a specific location, it is predestined to emerge in one of eight different temperature ranges, which are associated with changes in the ice. The experimentally observed enhancements, together with the findings on the gas composition of comet Halley, might enable an estimation of the gas composition in the region of comet formation.
TL;DR: The results suggest that the selective processing of targets specified by color or by shape is accomplished by attending to the targets’ locations.
Abstract: Subjects were presented with circular arrays of letters and were instructed to report first a given target (or targets) and then any other letters they could identify. The targets) was (were) a letter of a given color (Experiment 1) or a given shape (Experiment 2), or two letters of a given shape (Experiment 3). In all three experiments, the additional letters reported tended to be adjacent to the first reported target(s). The results suggest that the selective processing of targets specified by color or by shape is accomplished by attending to the targets’ locations.