1,723,538 research outputs found
Capital accumulation, unemployment, and the putty-clay
Full text linkThis note studies the dynamics of labor markets in a putty-clay framework. It analyzes the evolution of job creation and job destruction in an economy without market frictions. Unemployment and labor market flows emerge under putty-clay technologies because low productive jobs become unused factors. As capital accumulates, firms destruct low productive jobs by obsolescence. Simultaneously, the use of capital intensive technologies s new jobs by the low substitution between capital and labor.
A ‘putty-practically-clay’ vintage model with R&D driven biases in energy-saving technical change
Full text linkThis paper deals with the problem of tackling the adverse effect of output growth on environmental quality. For this purpose we use an intermediate sector that builds ‘putty-practically-clay’ capital consisting of an energy-raw capital amalgam used for final goods production. The putty-practically-clay model is a strongly simplified version of a full putty-clay model, that mimics all the relevant behaviour of a full putty-clay model, but that does not entail the administrative hassle of a full putty-clay vintage model. In addition to this, we introduce an R&D sector that develops renewable- and conventional energy-based technologies. The allocation of R&D activities over these two uses of R&D gives rise to an induced bias in technical change very much as in Kennedy (1964). In the context of our model, this implies that technological progress is primarily driven by the desire to counteract the upward pressure on production cost implied by a continuing price increase of conventional energy resources. Hotelling’s rule suggests that this price rise is unavoidable in the face of the ongoing depletion of conventional energy reserves. By means of some illustrative model simulations we study the effects of energy policy on the dynamics of the model for alternative policy options aimed at achieving GHG emission reductions. We identify the conditions under which energy policy might partly backfire and present some non-standard policy implications.macroeconomics ;
Technology Adoption under Relative Factor Price Uncertainty: The Putty-Clay Investment Model
Full text linkA plant has more flexibility in choosing among different technologies before undertaking an investment than after installing a specific machine. This paper argues that the irreversibility of factor intensity choice may play an important role in explaining the dynamics of investment in the presence of relative factor price uncertainty. A higher degree of irreversibility in the choice of factor intensity---characterized by the ex ante elasticity of substitution between different factors---leads to a larger negative effect of uncertainty in relative factor prices on investment. The empirical implications of the putty-clay investment model are examined using the plant-level Chilean manufacturing data for the period of time-varying exchange rate volatility. The econometric results show that the elasticity of substitution between imported materials and domestic materials is substantially higher at the time of a large investment and suggest that the irreversibility of factor intensity choice may potentially play an important role in explaining the impact of exchange rate volatility on investmentirreversible investment; putty-clay; technology adoption; uncertainty
Statutory Retirement Age and Lifelong Learning
Full text linkThe employability of an aging population in a world of continuous technical change is top of the political agenda. Due to endogenous human capital depreciation, the effective retirement age is often below statutory retirement age resulting in unemployment among older workers. We analyze this phenomenon in a putty-putty human capital vintage model and focus on education and the speed of human capital depreciation. Introducing a two-stage education system with initial schooling and lifelong learning, not even lifelong learning turns out to be capable of aligning economic and statutory retirement. However, lifelong learning can increase the number of people reaching statutory retirement age and hence reduce the problem of old age unemployment in an aging society.lifelong learning, retirement, unemployment, education system
Opportunity cost of CO2 emission reductions: developing vs. developed economies
Full text linkPresentamos evidencia empírica sobre convergencia en magnitudes medioambientales para países desarrollados y en vías de desarrollo. Además, partiendo de un modelo standard "putty-clay" de uso de energía, introducimos un stock de contaminación sobre el que se fija un objetivo de reducción de emisiones. El análisis teórico ofrece indicaciones sobre qué variables deberían ser objeto de futuros acuerdos de reducción de emisiones entre países heterogéneos.economía medioambiental, convergencia, reducción de emisiones, environment economy, convergence, emission reductions.
Models of energy use: putty-putty vs. putty-clay
Full text linkEnergy use is inelastic in time-series data, but elastic in international cross-section data. Two models of energy use reproduce these elasticities: a putty-putty model with adjustment costs developed by Pindyck and Rotemberg (1983) and a putty-clay model. In the Pindyck-Rotemberg model, capital and energy are highly complementary in both the short run and the long run. In the putty-clay model, capital and energy are complementary in the short run, but substitutable in the long run. We highlight the differences in the cross-section implications of the models by considering the effect of an energy tax on output in both models. In the putty-putty model, an energy tax that doubles the price of energy leads to a fall in output in the long run of 33%. In contrast, the same tax in the putty-clay model leads to a fall in output of only 5.3%.Power resources
Chalk putty: specimen preparation and aging properties
No full textChalk putty is a soil-like material that is formed when intact chalk is disturbed. Recently, it has become of special interest due to the development of offshore wind farms in the North and Baltic Seas, where in a number of sites piles are driven into chalk strata. Several pile tests reported in the literature show increased shaft capacity up to 4 months after driving. Although it is a widespread remark in the scientific publications that chalk properties improve over time, laboratory replications of this phenomenon are scarce and the results are inconclusive. The aim of this thesis is to develop a specimen preparation technique yielding representative specimens as well as feasible for commercial purposes. Thereafter, the evolution of the characteristics of chalk putty over time is assessed through laboratory tests. Triaxial with Bender Elements, Direct Simple Shear, Constant Rate of Strain and Thixotropy have been conducted on specimens aged up to 3 months. Finding that the behavior of chalk putty cannot be classified among the classic types of soils. On one hand, Constant Rate of Strain tests have shown that the response is comparable to silty soil, with a gradual transition between re-loading and virgin compression lines, leading to difficulty in the determination of the yield point. On the other hand, in shear, the critical state friction angle is in the range of dense sand. Regarding the volumetric response, there is an initial compressive response, succeeded by a constant volume phase during destructuration and eventual dilation or contraction at larger strains. Furthermore, it was determined that the material possesses thixotropic properties when mixed with de-ionized water. Finally, no increase in the shear strength or was recorded while the initial shear stiffness decreases with aging time -due to unconfined preservation of the samples. However, the ultimate dilatancy of the specimens increases over time, this may be a result of dissolved calcium carbonate during crushing and saturation which re-precipitates or re-cements around the grains.Applied Earth Science
Putty-clay capital and energy
Full text linkWe evaluate the ability of models with putty-clay capital and stochastic energy prices to account for the dynamics of energy use and output. Economists have noted a close relationship between changes in the price of energy and changes in output. Moreover, they have documents that this relationship is asymmetric: energy price increases are associated with large output charges while energy prices decreases are associated with small output changes. Finally, following energy price changes, energy use adjusts slowly over time. Standard models with putty-putty capital fail to reproduce the features of the data. In our study of putty-clay models, we first develop a simple characterization of equilibrium. We apply these results to solve a prototype model. Preliminary results suggest that models with putty-clay capital improve on putty-putty models in accounting for the data.Power resources
Aesthetic Correction of Peg Lateral with Resin Composite using Putty Index Technique : A Case Report
Full text linkMicrodontia involving only a single tooth is a rather common condition affecting mostly maxillary lateral incisor. One of the common forms of localised microdontia is that which affects maxillary lateral incisor, a condition that has been called the 'peg lateral'. Instead of exhibiting parallel or diverging mesial and distal surfaces, the sides converge or taper together incisally, forming a peg-shaped or cone-shaped crown. The root of such a tooth is frequently shorter than normal. The following case report describes a restorative protocol using direct composite resin build up using a putty index. Keywords: Peg lateral, Putty index, Direct veneer resin composit
On the Utilities of Putty and "Shippi" as Air-tight Materials in Woodenship Building
No full textThe author examined the strength of putty and "Shippi", which was locally used at Kushikino in Kagoshima prefecture, and proved that Shippi was superior in utility to putty as air-tight materials in wooden-ship building
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