Showing papers on "Elasticity (economics) published in 1979"
312 citations
TL;DR: In this paper, the authors consider government policies that insulate domestic producers and consumers from external price fluctuations, and study the effect of these policies on the elasticity of export demand.
Abstract: Johnson and Tweeten (1967, 1977) have provided estimates of the elasticity of export demand for specific agricultural commodities and aggregate agricultural exports. These estimates indicate the aggregate export demand for U.S. agricultural commodities is very elastic with respect to price, and the estimated elasticity is somewhat greater than 6.0 in both cases. The elasticities of export demand for specific commodities are also very large, ranging from -2.8 for soybeans to 10.18 for feed grains (Johnson). Theoretically, the elasticity of export demand may be quite large. However, the Johnson-Tweeten estimates do not consider government policies which insulate domestic producers and consumers from external price fluctuations. In order to study the effect of these policies on the elasticity of export demand, we (a) examine the formulation of the elasticity of export demand and the implication of price insulation policies, (b) review the trade policies of major importers and competing exporters, and (c) calculate the export demand elasticities for major agricultural commodities which incorporate price insulation policies. These export demand elasticities are much smaller than those of Johnson and
173 citations
TL;DR: In this article, a brand life cycle model is developed which incorporates carryover effects and obsolescence and allows for time-varying price responses, and an empirical study of 35 brands in seven different markets is conducted.
Abstract: A brand life cycle model is developed which incorporates carryover effects and obsolescence and allows for time-varying price responses. An empirical study of 35 brands in seven different markets s...
133 citations
TL;DR: It is concluded that human coronary and femoral arteries probably have similar elastic properties, i.e., Edyn, - 1.2 N.m−2 × 10−6, and six excised, human coronary arteries (subjects 14-40 years of age) were higher in comparison to the above in vivo data but agree with published values from other excised human vessels.
Abstract: We did this study to provide data on the elastic properties of coronary arteries, such being essential when considering the role of mechanical factors in coronary heart disease. In view of the necessity of using postmortem material to study human arteries, we made a preliminary study on the elasticity changes of a muscular artery (the femoral) after excision and cold storage. Dynamic (Edyn) and static (Edyn) incremental, elastic moduli of all arteries were calculated from simultaneously recorded pressure and diameter traces, the latter, in most instances, being obtained with an existing electrical caliper. A new, light-weight, strain-gauge caliper was developed to allow direct diameter records to be obtained from the left circumflex coronary artery (LCCA) on the beating canine heart. After excision and overnight cold storage, respectively, the canine femoral artery showed increases in diameter (9.2 and 11.6%), Edyn, (77 and 173%), and Edyn (46 and 99%). It is likely that these changes are applicable to the coronary arteries in view of the similarities in their medial structure. Ejyn for the canine LCCA was 1.23 ± 0.12 N.m−2 × 10−6 and was in excellent agreement with published data for femoral and carotid arteries. The mean and SBM values of Edyn and Edyn. for six excised, human coronary arteries (subjects 14-40 years of age) were 2.31 ± 0.49 and 4.46 ± 1.21 (SEM) N.m−2 × 10−6, respectively; these are higher in comparison to the above in vivo data but agree with published values from other excised human vessels. On the basis of the above reported postmortem increases in elasticity, it is concluded that human coronary and femoral arteries probably have similar elastic properties, i.e., Edyn, - 1.2 N.m"−2 × 10−6. Ore Res 45: 588-594, 1979
113 citations
TL;DR: In this paper, the quenching by an electric field of molecular orientation fluctuations in freely suspended ferroelectric smectic-$C$ films has been studied by light scattering, allowing absolute measurements of polarization, elastic constants, and viscosities.
Abstract: The quenching by an electric field of molecular-orientation fluctuations in freely suspended ferroelectric smectic-$C$ films has been studied by light scattering, allowing absolute measurements of polarization, elastic constants, and viscosities. Evidence is presented to demonstrate surface contributions to Frank elasticity and to show that Frank elasticity is nonlocal.
102 citations
85 citations
68 citations
TL;DR: In this article, the four independent material parameters of plane orthotropic elasti city are introduced as the effective stiffness, the effective Poisson ratio, the stiffness ratio and the shear parameter.
Abstract: The four independent material parameters of plane orthotropic elasti city are introduced as the effective stiffness, the effective Poisson ratio, the stiffness ratio and the shear parameter. It is proved that stress boundary value problems with zero resulting force on internal contours lead to stress fields that are independent of the effective stiffness and the effective Poisson ratio, and a general transformation is described which is equivalent to a change of the stiffness ratio. These properties suggest the importance of the remaining shear parameter, that has the interesting property of being invariant with respect to a 90 degree rotation of the principal axes of the material.
58 citations
57 citations
Patent•
03 Aug 1979
TL;DR: Improved bone connective prostheses are disclosed in this paper, where a reinforcement element carrying a polymer layer having varying modulus of elasticity is carried by the prosthesis and the interior surface of the polymer layer is attached to the reinforcement element.
Abstract: Improved bone connective prostheses are disclosed. The prostheses comprise a reinforcement element carrying a polymer layer having a varying modulus of elasticity. The exterior surface of the polymer layer constitutes the bone attachment surface of the prostheses and has the lowest modulus of elasticity. The interior surface of the polymer layer is attached to reinforcement element and has the highest modulus of elasticity. Portions of the polymer layer lying between the exterior and the interior surface of the polymer layer have moduli of elasticity which are intermediate with respect to the moduli of elasticity of the exterior and interior surface of the layer. The modulus of elasticity of the layer decreases in the direction of interior to exterior. The decrease in modulus of elasticity may be either continuous or incremental. The reinforcement element may have either a simple or a complex structure.
56 citations
TL;DR: A hand-held extensometer has been built for applying a uniform extension rate to skin in vivo and is currently being used in studies on the following groups of patients: Those being treated by the application of steroids to the skin and those receiving PUVA (photochemotherapy with long wavelength ultraviolet light) for psoriasis.
Abstract: A hand-held extensometer (see Figs i and 2) has been built for applying a uniform extension rate to skin in vivo. The apparatus is a development of one reported previously (Hutton, Ranu& Burlin, 1975). The motor and gearhead are now incorporated into the body of the extensometer and drive the lead screw direct, whereas before the lead screw was connected through a flexible drive to a remote motor and gearbox. This has eliminated excess vibration at high loads and provides much smoother extension of the skin. The apparatus is currently being used in studies on the following groups of patients: (1) Those being treated by the application of steroids to the skin. (2) Those receiving PUVA (photochemotherapy with long wavelength ultraviolet light) for psoriasis. The extensometer consists of two arms, one fixed the other movable, which are driven apart by means of the motor driven lead screw. Flat rectangular tabs at the end of the two arms are stuck to the skin surface by means of double sided adhesive tape. A number of attempts at the manufacture of the lead screw were required before mechanical vibration of the movable arm was eliminated. Finally, the lead screw was made with a central threaded portion, the rest being of cylindrical section. The carrier consists of a tube with polytetrafluoroethylene bushes at either end. The bushes are a running fit with the cylindrical section of the lead screw, while the central inner portion of the carrier is threaded to match the lead screw. The movable arm, which is attached to the carrier, runs in a slot in the outer housing. Thus, when the lead screw rotates, the carrier and movable arm slide along guided by the outer housing. Each end of the lead screw is located in a deep grooved ball bearing and one end is flexibly connected to the output gearhead shaft. The gearhead (240:1) is driven by a 12V d.c. reversible servomotor (18W, 8000 rev;min) so that the lead screw (40 t.p.i.) rotates at about 33 rev/min and the extension rate is 0-35 mm s. The motor and gearhead were chosen so that a load of up to 10 N on the movable arm did not cause a speed variation of more than i\",,. The force exerted on the skin by the fixed and movable arms is measured by means of two strain gauges attached at reduced sections on each of the two arms. The four strain gauges are wired as a
TL;DR: In this paper, the elastic constants of tourmaline crystals of known chemical composition have been measured by the ultrasonic phase-comparison method and the Debye temperature of the tourmalines derived from these constants is 785°K.
Abstract: Elastic constants of tourmaline crystals of known chemical composition have been measured by the ultrasonic phase‐comparison method. The values in 1012 dyn/cm2 are C11=3.050, C33=1.764, C44=0.648, C66=0.984, C14=−0.06, and C13=0.51. The Debye temperature of the tourmaline derived from the elastic constants is 785 °K.
Journal Article•
TL;DR: Small arterial resistance vessels have been mounted on a myograph that enabled their wall tension, T, and internal circumference, L, to be measured and controlled with a time resolution of about 4 ms, suggesting that the responses to isotonic and isometric releases may in part be due to active processes.
Posted Content•
TL;DR: In this paper, the elasticity of substitution between land and non-land input factors in the production of single-family housing over time is estimated using the CES production function, and the authors provide empirical estimates for 52 urban areas in 1967, 1971 and 1975.
Abstract: Production theory forms the basis of many models developed to examine urban spatial structure. The neoclassical concept of the elasticity of substitution between land and non-land (capital and land) input factors is at the heart of these models developed by Muth [1969], Mills [1972], and Kau and Lee [1976b]. Many urban problems, such as decentralization, cannot be completely understood without knowledge about the elasticity of substitution. The most common assumptions have been to arbitrarily constrain the elasticity of substitution to unity using the Cobb-Douglas production function or to assume that the elasticity of substitution is constant, but not necessarily unity, using the constant elasticity of substitution function.1 A number of studies have provided direct estimates based on the CES production function.2 As discussed by Hicks [1932] and Allen [1956], the elasticity of substitution (a) can be variable depending on output and/or factor combinations. Since the capital-land ratio varies significantly across cities, any a priori restriction may lead to possible specification bias. This study estimates the inter-urban variation in the elasticity of substitution between land and non-land input factors in the production of singlefamily housing over time. Section II of this paper develops a model of housing production using the variable elasticity of substitution (VES) production function developed by Revankar [1971]. Kau, Lee and Sirmans [1979] have used this approach to examine intra-urban variations in the elasticity of substitution. Section III provides some empirical estimates for 52 urban areas in 1967, 1971 and 1975. The elasticity of substitution is important in estimating the price elasticity of demand for urban residential land. Recent literature by Muth [1965, 1968, 1969] and Witte [1977] has estimated the price elasticity using aggregate data for the United States. Using the theory of derived demand, since land is an input into housing production, the price elasticity of urban residential land depends upon the price elasticity of demand for housing services, land's share of total value of housing, the elasticity of sub-
TL;DR: In this paper, the assumption of less than unity elasticity of substitution of substitution was considered when projecting the share of labor and factor shares, and the standard errors were shown to be remarkably low and the relatively small standard error and the close to 1.00 R2s leave very little room for bringing in another variable through which the hypothesis of variable elasticity in substitution would be tested.
Abstract: implies that Zarembka's (1970) suggestion that "for most empirical purposes the elasticity should be assumed to equal unity and the Cobb-Douglas Function employed rather than the CES Function" (p. 53) is unacceptable. On the contrary, since the estimated elasticities are long run elasticities the implication of less than unity elasticity of substitution should be seriously considered when projecting the share of labor. Finally, we want to praise the model used. Firstly, the standard errors are remarkably low. Secondly, in addition to the elasticity of substitution the other production function parameters (A and 8) are just identified. Hence (disregarding technological progress), predictions of value added and factor shares could be made once the physical quantities of labor and capital are known (exogenously given or predicted). Furthermore, the relatively small standard error and the close to 1.00 R2s leave very little room for bringing in another variable through which the hypothesis of variable elasticity of substitution would be tested. In principle, this possibility is not dismissed but according to the present experience, it probably would have to be tried with data of a lower level of aggregation. REFERENCES
TL;DR: ‘Kmetlcally-controlled’ throughout this drtlcle describes a diffusion-restricted series of movements that deliberately neglects the movement of all other cations.
TL;DR: In this paper, the distortions within beams and rods undergoing large displacements and rotations are derived from three-dimensional elasticity by an asymptotic procedure, based on the premise that strains vary more gradually along the rod than in transverse directions, taking full account of the shape of the cross section, the traction conditions on the lateral boundary and any material anisotropy.
TL;DR: In this paper, a revised formulation of guard cell mechanics, the material properties of the walls are re-examined and the estimated shear modulus of elasticity for guard cell walls is 2 MPa (20 bars) which is well within the limits of reported values for other biological tissues.
Abstract: In this revised formulation of guard cell mechanics, the material properties of the walls are re-examined. The observed elastic anisotropy of guard cell walls can be explained by non-random orientation of the cellulose micellae in the unstrained state. This micellar network is assumed to be loosely embedded in the wall matrix causing a two phase elongation process. In the first phase, the micellar network is ‘loose’ resulting in the walls behaving as an isotropic polymer when stretched. As the volume of the cell expands beyond some threshold, the network becomes ‘tightened’ and a second phase of elongation is initiated. During this anisotropic phase of cell expansion, wall elasticity reflectes changes in the orientation of the network to reduce its load.
Using the above theoretical analysis, a turgor-pressure versus lumen volume relationship is simulated for Vicia faba. The relationship between aperture and water potential for this species is also established. The simulated results agree with the experimental evidence reported for Vicia faba. The estimated shear modulus of elasticity for guard cell walls is 2 MPa (20 bars) which is well within the limits of reported values for other biological tissues.
01 Jan 1979
TL;DR: In this article, the problem of uniformly propagating finite crack in an infinite medium is solved using the dynamic equations of elasticity in 3-dimensions, and equal and opposite tractions are applied arbitrarily to the crack surfaces.
TL;DR: In this paper, the authors used the optical method of pseudocaustics for the experimental solution of plane elasticity, smooth contact problems for finite or infinite media in contact of arbitrary shape.
Abstract: T he optical method of pseudocaustics can be used for the experimental solution of plane elasticity, smooth contact problems for finite or infinite media in contact of arbitrary shape. This technique constitutes an alternative to the various numerical and experimental techniques for the approximate solution of plane elasticity contact problems. The success in the application of the method of pseudocaustics to plane elasticity contact problems is due to the possibility inherent in this method of the direct determination of the derivative Φ'( z ) of the complex potential Φ( z ) of N.I. Muskhelishvili along the boundaries of the media in contact. Then, the Muskhelishvili complex potentials, Φ( z ) and Ψ( z ), completely characterizing the state of stress and strain in a plane elastic medium, can easily be determined at any point of the media in contact after simple algebraic calculations. Two applications of the proposed method to contact problems of practical interest are also made.
TL;DR: In this article, the implications of equilibrium in a two-product, two-factor model for elasticity of product supply, which is found to depend upon input supply elasticities, alternative product demand elasticity, elasticity and substitution between production inputs, relative factor intensity, and relative importance of the product in its use of resources, are discussed.
Abstract: This paper draws out the implications of equilibrium in a two-product, two-factor model for elasticity of product supply, which is found to depend upon input supply elasticities, alternative product demand elasticity, elasticity of substitution between production inputs, relative factor intensity of the product, and relative importance of the product in its use of resources. These factors interact in a complex manner to determine supply elasticity. The author discusses related approaches of Buse, Muth, and Powell and Gruen, and considers several simplified examples in an attempt to provide an intuitive grasp of the workings of the model.