Showing papers by "Technion – Israel Institute of Technology published in 1981"
TL;DR: A survey of methods for imposition of radiation boundary conditions in numerical schemes is presented in this article, where combining of absorbing boundary conditions with damping (in particular, sponge filters) and with wave-speed modification are shown to offer significant improvements over earlier methods.
625 citations
TL;DR: A linear time approximation algorithm for the weighted set-covering problem is presented and produces a solution of weight which is at most twice the weight of an optimal solution.
450 citations
TL;DR: In this article, a multicomponent isotherm is derived based on the assumption that an exponential distribution of adsorption energies exists for each component in a k-component system.
318 citations
TL;DR: In 12 epileptic patients suffering from “absences” 8-channel EEG was recorded by telemetry and the autoregressive model was applied and the prediction coefficients being the basis for calculation of the poles of the predictor showed specific pattern linked with the occurrence of the siezure.
Abstract: In 12 epileptic patients suffering from "absences" 8-channel EEG was recorded by telemetry. The autoregressive model was applied to the signal and the prediction coefficients being the basis for calculation of the poles of the predictor. The location of the poles in thez- ands-planes was described as a function of time for 0.1 s steps along the pre-seizure EEG. In 10 of the 12 patients, and in 25 of the 28 recorded seizures this presentation of the poles of the predictor showed specific pattern linked with the occurrence of the siezure. The trajectory of the "most mobile pole" during the pre-seizure period could aid in the prediction of the seizure by several seconds.
283 citations
TL;DR: In this paper, the authors considered the general problem of root-clustering of a matrix in the complex plane and introduced two types of regions which constitute the largest class of S known to date.
Abstract: We consider the general problem of root-clustering of a matrix in the complex plane: Let A \in C^{n \times n} and S \subset C . Find the largest class of S and an algebraic criterion which is necessary and sufficient for \lambda_{i}[A] \in S, i=1,2,..., n . We introduce two types of regions which constitute the largest class of S known to date. The criterion is presented both for open regions and closed ones. The results are used to define a design methodology for control systems. Moreover, all classical results are shown to be special cases of the present theory.
262 citations
10 Jun 1981
TL;DR: A model for synchronized parallel computation is described in which all p processors have access to a common memory and this model is used to solve the problems of finding the maximum, merging, and sorting by p processors.
Abstract: A model for synchronized parallel computation is described in which all p processors have access to a common memory. this model is used to solve the problems of finding the maximum, merging, and sorting by p processors.
252 citations
TL;DR: A linear implementation of the optimal universal data compression methods of Lempel and Ziv is described and the main tool is McCreight's algorithm for constructing suffix trees.
Abstract: A linear implementation of the optimal universal data compression methods of Lempel and Ziv is described. The main tool is McCreight's algorithm for constructing suffix trees. Both bounded and unbounded memory are considered.
236 citations
TL;DR: All the elementary operations including allocation of processors to their jobs are taken into account in deriving the depth complexity and not only comparisons.
188 citations
TL;DR: In this paper, the qualitative nature of infinite clusters in percolation models is investigated and the results apply to both independent and correlated percolations in any dimension, concern the number and density of infinite cluster, the size of their external surface, the value of their (total) surface-to-volume ratio, and the fluctuations in their density.
Abstract: The qualitative nature of infinite clusters in percolation models is investigated. The results, which apply to both independent and correlated percolation in any dimension, concern the number and density of infinite clusters, the size of their external surface, the value of their (total) surface-to-volume ratio, and the fluctuations in their density. In particular it is shown thatN0, the number of distinct infinite clusters, is either 0, 1, or ∞ and the caseN0=∞ (which might occur in sufficiently high dimension) is analyzed.
177 citations
TL;DR: Two solution techniques are presented and applied to solve in a closed form realistic air combat problems modelled as perfect information zero-sum differential games and the method of singular perturbations is analyzed.
Abstract: : Two solution techniques are presented and applied to solve in a closed form realistic air combat problems modelled as perfect information zero-sum differential games. Optimal missile guidance and avoidance solved as a linear differential game with bounded control. Medium range air to air interception is analyzed applying the method of singular perturbations. For more complex problems the combination of the two techniques may be required. (Author)
165 citations
TL;DR: Messenger RNA obtained from spinach cotyledons directs the synthesis of all five CF1 subunits in vitro in a rabbit reticulocyte translation system indicating that they originate in the nucleus and are imported into the chloroplast.
Abstract: 1)
Messenger RNA obtained from spinach cotyledons directs the synthesis of all five CF1 subunits in vitro in a rabbit reticulocyte translation system. The alpha, beta and epsilon subunit polypeptides were found as translation products from ptRNA and whole-cell poly A−-RNA. The gamma and delta subunits were synthesized from whole-cell poly A+-RNA as precursors of substantially greater molecular weight indicating that they originate in the nucleus and are imported into the chloroplast. High resolution electrophoresis, immunoprecipitation with antibodies against individual CF1 subunits (Nelson et al. 1980), and proteolytic peptide mapping were employed to identify the products.
2)
The genes for alpha, beta and epsilon subunits of CF1 were located by hybrid-selected translation with matrix-immobilized ptDNA fragments of known map position. The genes for all three CF1 subunit polypeptides are located in the large single-copy segment (cf. Herrmann et al. 1980b) of the circular ptDNA and each gene appears to be present once on the chromosome. The genes for the beta and epsilon subunits lie near each other in immediate vicinity to the structural gene for the large subunit of ribulose bisphosphate carboxylase/oxygenase. The gene for the alpha subunit is separated by approximately 40 kbp from this gene cluster, and located near the gene for the 32 kd photosystem II polypeptide (Driesel et al. 1980).
3)
Restriction fragments of spinach ptDNA with CF1 subunit genes were cloned into pBR 322 and used to construct detailed maps.
TL;DR: In this article, the effect of tensial strength on the stability of slopes was evaluated using a variational approach to limiting equilibrium problems, and it was found that the maximum depth of tension cracks is 25% of the slope height, and this value occurs for vertical slopes.
TL;DR: It is suggested that in most cases, various forms of breathing disorders in sleep are responsible for EDS.
Abstract: Detailed data about sleep habits, sleep complaints, life style, work, past and present health were obtained from 1,502 industrial workers. In agreement with previous studies, one-third of the workers reported having problems with sleep. A relatively large percentage of workers complained of excessive daytime somnolence (EDS), which was unrelated to sex, age, education, and area of origin. Compared to the total population, workers complaining EDS had signficantly more pre- and postsleep complaints, midsleep disturbing phenomena, and work accidents, and they were less satisfied with their work. They also had a significantly higher prevalence of asthma, high blood pressure, headaches, and arthritis and ulcers, and they consumed significantly more medications. Based on the cluster of pre- and postsleep complaints of workers complaining of EDS, and on preliminary results from the second phase of this project (which includes laboratory polysomnographic recordings), it is suggested that in most cases, various forms of breathing disorders in sleep are responsible for EDS.
TL;DR: In this paper, two nonlinear transformations, the D-transformation to accelerate the convergence of infinite integrals and the d -transformation for infinite series, are presented, and the computational aspects of these transformations are described in detail.
TL;DR: It is suggested that increased upper airway resistance and increased nasal discharge are responsible for the disordered breathing in sleep and for the "microarousals' in patients with allergic rhinitis.
Abstract: The influence of obstructed nasal passages on deep was investigated in 14 patients with allerigic rhinitis. Disordered breathing in sleep was found in all patients in the form of periodic breathing...
TL;DR: In this article, the electrical resistivity of peroxide and radiation crosslinked polyethylene/carbon black compounds was studied as a function of black concentration and temperature in heating/cooling cycles.
Abstract: The electrical resistivity of peroxide and radiation crosslinked polyethylene/carbon black compounds was studied as a function of black concentration and, temperature in heating/cooling cycles. Different carbon blacks in compounds with polyethylene responded differently, regarding electrical resistivity, to the effect of crosslinking. In one case (fine black) the resistivity and PTC (positive temperature coefficient) effect did not significantly change, whereas in another case (coarse black) the effect of crosslinking-was to significantly increase the resistivity and reduce the PTC effect. The main advantages of crosslinking were to give compounds having good electrical reproducibility and to practically eliminate the NTC (negative temperature coefficient) effect in compounds containing fine, coarse, or mixtures of carbon blacks. Crosslinked compounds containing mixtures of carbon blacks have shown good conductivity, electrical reproducibility, and switching properties.
TL;DR: In this article, the authors developed criteria for the cushioning properties of plastic foams based on their stress-strain curves, and evaluated two flexible polyurethane foams and two semirigid bonded polyurethene chipfoams.
Abstract: Evaluation criteria for the cushioning properties of plastic foams were developed on the basis of their stress-strain curves. The energy-absorption efficiency and ideality parameters have maxima when plotted against stress. The maximum in the efficiency curve represents the strain range where maximum energy is absorbed by the foam at the corresponding stress; the higher and flatter this maximum, the better the cushioning properties of the foam. The maximum in the ideality curve represents the range where the foam transmits a constant force to the packaged product. Two flexible polyurethane foams and two semirigid bonded polyurethane chipfoams were evaluated by the proposed method.
TL;DR: In this article, the effects of the mass of sand impacted and the impact angle were determined and details of the surface damage were characterized, while progressive mass loss was observed on all materials and one glass-epoxy composite exhibited erosion which was less than that of the other composites by half an order of magnitude; this is attributed to better adhesion between the matrix and fibers, a higher percentage of fiber loading and lower porosity.
TL;DR: The present study has indicated that since the acetylenic compounds resemble the enzyme substrates the distance between the aromatic ring and the N‐propargyl terminal is crucial in designating the type A or type B MAO inhibitory property.
Abstract: 1 A number of aromatic-N-propargyl (acetylenic) compounds and indoleamines were tested for their inhibitory action on monoamine oxidase (MAO) type A and type B using the substrates 5-hydroxytryptamine (5-HT), beta-phenylethylamine (PEA) and dopamine. 2 Structure activity studies with aromatic-N-propragyl (acetylenic) derivatives have shown that MAO inhibitory potency is least dependent on the aromatic portion of the compounds. N-methylated propargyl derivatives are the most active and replacement of the methyl group with a higher alkyl or aromatic group results in significant reduction of activity. The triple bond in the N-propargyl portion is absolutely essential for activity and must be beta-to the nitrogen. It is the acetylenic group that gives these compounds their irreversible MAO inhibitory property. 3 The present study has indicated that since the acetylenic compounds resemble the enzyme substrates the distance between the aromatic ring and the N-propargyl terminal is crucial in designating the type A or type B MAO inhibitory property. For MAO type A inhibition, a distance equivalent to at least three carbon units is required, while for the inhibition of the B type enzyme this distance can be 1 or 2 carbon units. 4 The compounds AGN-1133 and AGN-1135 show most promise in Parkinson's disease or as anti-depressants because of their irreversible selective type B MAO inhibition in vitro and in vivo. 5 A number of indoleamine derivatives were found to be reversible selective type A inhibitors.
13 Jul 1981
TL;DR: Increasing stimulus presentation rate had a significant effect on detection of abnormality in ABEPs from the patients examined, and measures of the effect of rate may complement the traditional measures that are primarily sensitive to white matter lesions.
01 Jan 1981
TL;DR: Glucose fermentation by Saccharomyces cerevisiae immobilized by entrapment in agar, carrageenan, alginate and polyacrylamide gels, was compared to that of freely suspended cells at concentrations of 10–50% (w.w.) sugar.
Abstract: Glucose fermentation bySaccharomyces cerevisiae immobilized by entrapment in agar, carrageenan, alginate and polyacrylamide gels, was compared to that of freely suspended cells at concentrations of 10–50% (w.w.) sugar. The rate of ethanol production by the entrapped cells was 20–25% higher than that of the free cells. Concentrations of up to 14,5% w/w ethanol (30% glucose initial concentration) could be obtained. A number of hypotheses for the improved alcoholic fermentation are discussed.
TL;DR: AGN 1135 possesses tyramine antagonistic activity which is qualitatively similar to that of (−)‐deprenyl but which cannot satisfactorily be explained by inhibition of neuronal or granular amine uptake.
Abstract: 1 The effects of the irreversible monoamine oxidase (MAO) inhibitors, AGN 1133, AGN 1135 and (-)-deprenyl, on tyramine and noradrenaline responses and uptake of [3H]-metaraminol were investigated in the isolated vas deferens of the rat. Uptake of [3H]-metaraminol and [3H]-octopamine was compared in mouse vas deferens. The modification of tyramine and noradrenaline-induced pressor responses by AGN 1133 and AGN 1135 was examined in anaesthetized rats and cats. 2 AGN 1133 (7.5 x 10(-6)M) greatly potentiated responses to tyramine in the rat isolated vas deferens. Both AGN 1135 and (-)-deprenyl inhibited tyramine responses selectively at concentrations above 10(-5)M (which caused almost complete inhibition of MAO types A and B) but tyramine responses were potentiated on washing out the inhibitors. 3 AGN 1135 (10(-4)M) and (-)-deprenyl (10-5)M) inhibited [3H]-metaraminol uptake by about 20% in rat and mouse vas deferens; neither inhibitor affected [3H]-octopamine uptake in mouse vas deferens. Desmethylimipramine (10(-6)M) inhibited amine uptake by more than 70%. 4 AGN 1133 (1.5 mg/kg) potentiated pressor responses to tyramine in rats and cats whereas AGN 1135 (1.5 mg/kg) did not. 5 AGN 1135 possesses tyramine antagonistic activity which is qualitatively similar to that of (-)-deprenyl but which cannot satisfactorily be explained by inhibition of neuronal or granula amine uptake.
TL;DR: In the majority of instances spermatozoa lost their motility when mixed with fresh urine specimens and it is suggested that patients with retrograde ejaculation should adequately increase their fluid intake before recovery of sperm from their bladder for artificial insemination.
TL;DR: Both REM deprivation and total sleep deprivation disrupted the 100 min periodicity in stage 1 and modified the distribution of stage 2 toward a bimodal rather than a unimodal distribution.
TL;DR: In this paper, a computerized adaptive control grinding system was developed to optimize both the grinding and dressing conditions for maximum removal rate subject to constraints on workpiece burn and surface finish.
Abstract: A computerized adaptive control grinding system has been developed. The system is designed to optimize both the grinding and dressing conditions for maximum removal rate subject to constraints on workpiece burn and surface finish. The control strategy of the system is based upon online convergence along a predetermined optimal trajectory derived from grinding theory. A pilot system was developed and illustrative results are presented which demonstrate its performance and the practical feasibility of the optimization concept.
TL;DR: In this paper, the authors explain the formation of runoff during rainfall at low rates that do not exceed infiltration capacity, partial area contribution to runoff, net recharge of groundwater by low-rate rainfall, formation of rills and gullies in relatively dry area, delay of runoff after a certain total amount of rain irrespective of rain intensity, variations in soil formation in different parts of the landscape, poor distribution of irrigation water in nonplane fields, and leaching of the soil surface by water that was assumed to run only above the surface.
Abstract: Nonisotropic sloping soil leads to a horizontal flow component during rain and infiltration. Splashing of raindrops and flow in the transition zone between the soil bulk and the air also lead to lateral flow. The result is concentration of moisture in concave spots to the point of saturation and even seepage out of the soil. The same occurs at steep soil cuts. Such moisture concentration can explain the formation of runoff during rainfall at low rates that do not exceed infiltration capacity, partial area contribution to runoff, net recharge of groundwater by low-rate rainfall, the formation of rills and gullies in a relatively dry area, delay of runoff after a certain total amount of rain irrespective of rain intensity, variations in soil formation in different parts of the landscape, poor distribution of irrigation water in nonplane fields, and leaching of the soil surface by water that was assumed to run only above the surface.
01 Jan 1981
TL;DR: It was demonstrated that upon reconstitution of the proton ATPase into phospholipid vesicles, the enzyme system can utilize an artificial proton gradient for ATP formation, and it is still unknown whether phosphate is covalently bound to the enzyme during the phosphorylation activity of proton ATPases.
Abstract: Publisher Summary This chapter discusses proton–ATPase of chloroplasts. It was demonstrated that upon reconstitution of the proton ATPase into phospholipid vesicles, the enzyme system can utilize an artificial proton gradient for ATP formation. In a study described in the chapter, proton–ATPases were identified and isolated from several energy transducing membranes. They are composed of two distinct structures: (1) a catalytic sector that is hydrophilic in nature and (2) a membrane sector that is hydrophobic in nature. The chloroplast proton–ATPase complex possesses similar structures and thus, they are applicable for the rest of the energy transducing membranes. Chemical reactions must be involved in the translation of proton motive force into the chemical energy in ATP. There are strong indications that for every electron transferred from water to a Hill acceptor, two protons are pumped inside the thylakoid membrane. The measured ΔpH contained sufficient energy to drive phosphorylation against its maximum potential, provided three protons are used by the ATPase complex per one ATP formed. Therefore, there is a possibility that the P: 2e ratio for noncyclic photophosphorylation is about 1.3. The mechanism by which three protons are involved in a single chemical event is difficult to visualize, and it might be that the third proton imposes a proper conformation in one of the catalytic steps. However, it is still unknown whether phosphate is covalently bound to the enzyme during the phosphorylation activity of proton ATPases