Showing papers by "Tel Aviv University published in 1977"

Inflation and costs of price adjustment

Abstract: How MUCH? Companies that sell through catalogs run into a pricing problem. Fast rising prices threaten to make catalog quotes out of date. Montgomery Ward & Co. which bought cautiously for its winter catalog, says it is " keeping its fingers crossed " that prices won't surge much in the near future. An official of Oak Supply & Furniture Co., Chicago, complains that the company's catalogs have been obsolete in terms of prices before they got into customers' hands the past two years. Basco Inc., Cherry Hill, N.J. mailed its latest catalog just a few weeks ago but already is reviewing some prices. J. C. Penney Co. says it stands behind prices during the approximately sevenmonth life of its semiannual catalogs. Like other companies, it gets guarantees from many vendors that they won't raise their prices for specified periods. But more catalog sellers tell customers prices are subject to change. Jewelcor Inc. puts such a warning on its catalog's jewelry pages. Some companies, such as Basco, consider putting out catalogs more frequently to keep up with prices. For the last two years Sears Roebuck has issued some 20 special catalogs twice rather than once a year. (Wall Street Journal-10/31/74).

Diffusional-Thermal Theory of Cellular Flames

Abstract: It is shown that the formation of cellular structure in a flame is conditioned by diffusion and heat conduction effects and is independent of the hydrodynamics of the perturbed flame. It is proved that cellular flames are formed only when a sufficiently light reactant of the combustible mixture is present in a low concentration. If there is an excess of the light reactant, a plane flame front is absolutely stable (in the framework of the diffusional-thermal model) or shows a noncellular periodic structure (hydrodynamic model)

The dimension of almost spherical sections of convex bodies

Abstract: © Séminaire analyse fonctionnelle (dit \"Maurey-Schwartz\") (École Polytechnique), 1975-1976, tous droits réservés. L’accès aux archives du séminaire d’analyse fonctionnelle implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/legal.php). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright.

Critical Behavior of the Complex Dielectric Constant near the Percolation Threshold of a Heterogeneous Material

Abstract: The behavior of the effective bulk conductivity ${\ensuremath{\sigma}}_{e}$ and of the effective bulk dielectric constant ${\ensuremath{\epsilon}}_{e}$ of a heterogeneous mixture of a conducting phase and an insulating dielectric phase is analyzed in the vicinity of the percolation threshold. Exact considerations of a general nature lead to the conclusion that ${\ensuremath{\epsilon}}_{e}$ diverges as the conductivity threshold is approached from either side. The introduction of a homogeneity or scaling hypothesis leads to relations between the critical behavior of ${\ensuremath{\sigma}}_{e}$ and ${\ensuremath{\epsilon}}_{e}$.

Minimal coupling and the symplectic mechanics of a classical particle in the presence of a Yang-Mills field.

Abstract: This note is to show how to use symplectic geometry to write equations of motion of a “classical particle” in the presence of a Yang-Mills field, for any gauge group, G, and any differentiable manifold, M. In the case that M is Minkowski space and G = U(1), the equations reduce to the Lorentz equations for a charged particle in an electromagnetic field. Our procedure in the general case uses the connection form as defined on the principle bundle to introduce a symplectic structure on certain associated bundles and is automatically gauge invariant.

Relation between the gradient of the ATP/ADP ratio and the membrane potential across the mitochondrial membrane.

Abstract: The relation between the intramitochondrial and extramitochondrial ratio ATP/ADP, the transmembrane potential and pH gradient is investigated in the present communication. For this purpose mitochondria are equilibrated with added [14C]ATP in the presence of substrate and oligomycin for eliminating phosphate transfer by ATPase. The membrane potential was measured by the distribution of 86Rb+ in the presence of valinomycin, the deltapH by the distribution of [14C]acetate. In the energized state by varying deltapsi between 60 and 160 mV, the internal (ATP/ADP)i is decreased 30-fold, the external (ATP/ADP)e remains largely constant. As a result, the deltalog (ATP/ADP)e/(ATP/ADP)i = deltalogphi is increased linerly with deltapsi according to the following relation: deltalogphi = 0.85 deltapsi - 0.35. The deltapH was changed between 0.1 and 0.8 by increasing the Pi concentration causing only a minor decrease of deltalogphi would be expected if the ATP-ADP exchange has a significant electroneutral portion. Also in the uncoupled and respiration-inhibited state the same function between deltalogphi and deltapsi is found as in the energized states. It is concluded that under these conditions the ATP-ADP exchange is largely electrical.

Space partitioning by stony corals soft corals and benthic algae on the coral reefs of the northern Gulf of Eilat (Red Sea)

Abstract: The major faunistic and floristic components occupying space on the coral reefs of the northern Gulf of Eilat (Red Sea) are stony corals, soft corals and benthic algae. The percent living coverage of the three components and the relative abundance of the different species of each component were studied by line transects, on the reef flats and the upper forereef zones of nine localities. A wider and higher range of living coverage values of stony corals were recorded at the upper fore-reef zones (18.30–49.09%) compared with the reef flats (5.50–31.66%) at the different stations. The most abundant stony corals on the reef flats areCyphastrea microphthalma, Stylophora pistillata, Favia favus, Porites lutea, Platygyra lamellina and the hydrozoanMillepora dichotoma. The fire coralM. dichotoma dominates the upper fore-reef zone in most of the stations. The average percent living coverage of soft corals on the reef flats ranged between 0.20 and 17.06%, and on the upper fore-reef zones between 1.68 and 15.13%. Seventy percent of the total living coverage of the soft coral community is contributed by 2 to 3 species. They tend to form large monospecific “carpets”, such as those composed ofSinularia sp.,Sarcophyton glaucum andLobophytum pauciflorum. The common benthic algae on the coral reef studied occur as turfs or macroscopic noncalcareous algae. They play a significant role in occupying space, especially on the reef flats. The most abundant algae recorded in all localities are the turfsSphacelaria tribuloides, Jania sp. and the macroscopic non-calcareous algaeTurbinaria elatensis andColpomenia sinuosa. Comparison between reef flats and upper fore-reef zones, in terms of average living cover of stony corals, shows that the variation among the reef flats is grater than the variation among the upper fore-reef zones. However, there is no significant variation in the average living coverage of soft corals between these two zones. Annual living-coverage values of algae on the reef flats are significantly higher than those of the upper fore-reef zones. Extremely low tides occurring periodically but unpredictably at Eilat cause mass mortality of the benthic communities on the reef flats reopening new spaces for settlement. The coexistence of stony corals, soft corals and algae on the reef ecosystem is due to different biological properties of each component. Opportunistic life histories of certain stony corals and most algae enable quick colonization of newly opened spaces. Lack of predators, high tolerance against abiotic factors and ability to form large aggregates of colonies are suggested as possible factors supporting the existence of soft corals in shallow water. Biological factors such as competition, predation and grazing pressure play an increasingly important role in controlling space utilization by the components studied with the advancement of succession.

Circulating nucleic acids in higher organisms.

Abstract: Publisher Summary This chapter discusses the circulating nucleic acids in higher organisms. DNA is able to leave bacteria and enter other bacteria and the mechanisms and situations involved are readily understood. Bacterial DNA can move from members of one strain to those of another by means of conjugation or transduction, which does not strictly involve extracellular release of DNA. Bacteria possess several extra chromosomal factors including the F factor (the first fertility factor), R factors (antibiotic resistance transfer factors), and bacteriocinogenic factors, which are distinguishable by their molecular weight. F and R factors and some bacteriocinogens have a molecular weight of 6–140 × l0 6 , corresponding to 100 to 200 genes, while many bacteriocinogens have a molecular weight of 4–5 × 10 6 —about 15 genes. Transformation also has been achieved by providing one strain of bacteria with non-purified DNA found in the culture medium of another strain.

Gauge theory of gravity and supergravity on a group manifold

Abstract: The natural arena for the physics of gravity, supergravity and their enlargements appears to be the group manifold of the Poincare group P, the graded Poincare group GP of supersymmetry, and the corresponding enlargements. The dynamics of these theories correspond to geometrical algorithms in P and GP. Differential geometry on Lie groups is reviewed and results applied to P and GP. Curvature, gauge transformations and factorization are introduced. Also reviewed is the general coordinate transformation group and a hybrid gauge transformation, the anholonomized G.C.T. gauge. A study is made of the construction of an action, including the introduction of a set of special 2 forms, the ''pseudo curvatures.'' The possibilities of factorization in supersymmetry are analyzed. The version of supergravity is present which has now become a completely geometrical theory.

Anthropogenic impact on the albedo of the earth

Abstract: The impact of man and animal on the Earth's surface albedo (reflectivity), until recently believed to be quite small, or not considered at all, is analyzed. Discussion is presented of changes in the albedo due to the heat island effects of cities on snow cover, to agricultural cultivation, irrigation, and to overgrazing; the latter of which is emphasized. In arid climates, protected steppe areas have a low albedo due to dark plant debris accumulating on the crusted soil surface, whereas the same type of terrain, when overgrazed, exhibits a high albedo of trampled, crumbled soil. Extrapolating from observed spatial differences between overgrazed terrain and natural steppe, it is suggested that anthropogenic pressures mainly due to overgrazing could have had a very significant effect on the Earth's surface albedo both regionally and as a global average during the last few thousand years. The Earth's surface albedo presently might be 0.154 whereas it might have been 0.141 about 6000 years B.P. Thus, the surface albedo could have increased by Δa = 0.013, or by nearly 10% of its value when steppe areas were in their ‘virgin’ state. The hypothesized increase would be much larger in the Northern hemisphere than in the Southern. There are uncertainties even in the second digit of the suggested value for the present day albedo, and thus certainly for the albedo in the past. Seasonal mapping of the surface albedo from LANDSAT type satellites is recommended.

Critical exponents for percolation conductivity in resistor networks

Abstract: The conductivity of two-dimensional and of three-dimensional cubic binary random resistor networks is shown to obey a power-law dependence on the conductivity ratio at the percolation threshold. The relation recently derived by Straley between the exponent of this power law and the other two critical exponents of the conductivity above and below the percolation threshold is accurately obeyed. Extension of the scaling laws for a complex dielectric function of a binary network is provided.

On the Use of Double Sampling Schemes in Analyzing Categorical Data with Misclassification Errors

Abstract: In order to resolve the difficulties involved in inference from a sample of categorical data obtained by using a fallible classifying mechanism (usually inexpensive), we consider, as in Tenenbein (1970, 1971, 1972), the utilization of an additional sample. The second sample is subjected to a simultaneous cross-classification of its elements by the fallible mechanism and by some true (usually expensive) classifying mechanism. The setup is general; i.e., the discussion can be applied to any multidimensional cross-classified data obtained by unrestricted random sampling. Two methodologies are presented: (i) a combined maximum likelihood (ML) and least squares (LS) approach and (ii) a complete-LS approach. Both methodologies are illustrated using real data.

Tumor-bound immunoglobulins: in situ expressions of humoral immunity.

Abstract: Publisher Summary An accurate and precise evaluation of tumor-host relations is an essential prerequisite for a rational approach to cancer therapy, in particular immunotherapy, and to a correct assessment of prognosis The host–tumor relationship is assessed mainly by the capacity of immune components, such as lymphocytes, macrophages, or antibodies, to react in vitro against tumor cells It is noted that the expression of immunity is not equal in all sites of the body It is significant to evaluate in situ tumor immunity concerning the immune-histology of the malignant area in relation to prognosis or treatment This chapter summarizes the available data on the presence, properties, and functions of humoral immune components, mainly immunoglobulins, at the site of malignant tumors It focuses on the studies that deal with nonlymphoid malignancies Common methods used to detect tumor-associated immunoglobulins (TAIg) include (1) the treatment of tumor fragments with low pH buffers or with salt solutions of high molarity, (2) direct membrane immunofluorescence of tumor cells, (3) radioimmunofixation, and (4) mixed hemadsorption The chapter considers several TAIg such as Ig class and IgG subclass

Transitional boundary layer spot in a fully turbulent environment

Abstract: A spark was used to initiate and mark in time a turbulent spot in an initially laminar boundary layer. This marked spot of turbulence merged and interacted with the natural turbulent boundary layer generated by a row of spherical trips. By using a digital technique to align individual spot signatures, thus correcting for variations in the transit time to a given measurement station, a structure was tracked over a streamwise extent of 70 average turbulent boundary‐layer thicknesses. The scale of the structure is of the order of 10δ in the streamwise direction becoming 2−3δ in the interface region of the boundary layer and is less than 4δ in the spanwise direction, in spite of the fact that no spanwise alignment was performed. The structure is characterized by a convection speed of 0.9U∞. It exhibits features in detailed agreement with those at the outer region of the turbulent boundary layer (interface region) and is consistent with existing two‐ and three‐point space‐time correlations.

Sexual Arousal and Aggression: Recent Experiments and Theoretical Issues

Abstract: Despite considerable theorizing on the subject, empirical research focusing on hypothesized links between sexual arousal and aggression has been slow to follow. Recent studies have found that under differing experimental conditions there are both mutually facilitative and inverse relationships between sex and aggression. Available models designed to account for these findings are examined. An alternative model is proposed incorporating distinctions between hostile and assertive aggression and placing emphasis on the role of discriminative inhibitory and disinhibitory cues. Some implications and possible applications of this model for human sexual behavior are considered.