U-shaped Path Research Articles

The Environmental Kuznets Curve from Multiple Perspectives

The analysis finds that in addition to U-shaped paths of environmental quality arising for growth in income per capita, growth in population can also produce socially efficient patterns that are U-shaped. Sufficient conditions for both types of paths are identified for a range of models and parameters, including symmetrical models with homothetic, constant-returns functions such as with CES functions. Similar results are also shown to arise in decentralized economies under either homogeneous or heterogeneous income levels.

The Environmental Kuznets Curve from Multiple Perspectives

The analysis finds that in addition to U-shaped paths of environmental quality arising for growth in income per capita, growth in population can also produce socially efficient patterns that are U-shaped. Sufficient conditions for both types of paths are identified for a range of models and parameters, including symmetrical models with homothetic, constant-returns functions such as with CES functions. Similar results are also shown to arise in decentralized economies under either homogeneous or heterogeneous income levels.

Equity Overvaluation and Capital Misallocation? A Revealed Preference Approach

Many economists believe that the stock market plays an important role in efficiently allocating capital to its most productive uses. This standard story of the stock market was called into question by events in the late 1990s, when some observers believed that there was stock market misvaluation that led to a misallocation of capital. Both the standard and misallocation stories involve discount rates and, to differentiate between the two stories, this paper examines the discount rates used by firms in making their investment decisions. The most common story for how misvaluation might affect investment runs as follows. Investors become excited about particular firms. In their excitement, they bid up the prices of these firms. Overvalued shares lower the perceived cost of equity capital. If managers act on this lower perceived cost, they will issue new shares, lower the discount rate used in evaluating investment projects, and increase investment spending. This story could be wrong (or at least of minor importance). Firms with high stock market prices may simply be firms that have particularly good investment opportunities. The central core of the standard story of capital allocation involves rates of return and discount rates. Favorable shocks - an increase in demand or a technical improvement - raise returns to capital for the fortunate firm. A firm earning high returns (relative to its cost of capital or discount rate) increases its capital stock until the return on the marginal unit of capital again equals the discount rate. Absent externalities, capital is being allocated optimally. We use a revealed preference approach that relies on the pattern of investment spending - combined with investment theory - to estimate the discount rates used by managers. The standard story predicts that glamour firms should have discount rates equal to the risk-adjusted market rate. The misallocation story predicts that glamour firms should have discount rates below the market rate. The standard story also predicts the discount rates for glamour firms should have a flat time path, while the misallocation story predicts a U-shaped time path. Based on a panel dataset of over 50,000 firm-year observations, we find support for both stories. The behavior of glamour firms with good measured investment opportunities is best described by the standard story, while the misallocation story provides the most appropriate interpretation of the behavior of glamour firms with poor measured investment opportunities.

The 'Dynamic' of Job Competition During the ICT Revolution

Our paper seeks to gain insights on the e®ect of labor market institutions on the evolution of overeducation (job competition), unemployment inequalities and job instability during the polarization process of the labor market fostered by the di®usion of novel technologies. Based on micro data, we ¯rst present some stylized facts characterizing the occidental countries' labor markets. We then develop an endogenous job destruction framework µa la Mortensen and Pissarides (1994) where each individual is endowed with a given ability level. The process of contact between the set of heterogeneous workers and ¯rms is represented by a traditional matching function. The segmentation of the labor market between workers having the required ability to occupy cognitive jobs (where novel technologies are used) and the rest of the workers occupying simple jobs is endogenously determined. Firms o®ering a cognitive job support a set up cost but ICT are assumed to improve their productivity. When simulated the model manages to reproduce the U-shaped path followed by the ability requirements needed in cognitive positions as ICT got increasingly di®used. Furthermore, we also draw conclusions concerning the evolution of job stability, the size of each labor market segment and the unemployment rates.

Evolutionary Paths Underlying Flower Color Variation inAntirrhinum

To understand evolutionary paths connecting diverse biological forms, we defined a three-dimensional genotypic space separating two flower color morphs of Antirrhinum. A hybrid zone between morphs showed a steep cline specifically at genes controlling flower color differences, indicating that these loci are under selection. Antirrhinum species with diverse floral phenotypes formed a U-shaped cloud within the genotypic space. We propose that this cloud defines an evolutionary path that allows flower color to evolve while circumventing less-adaptive regions. Hybridization between morphs located in different arms of the U-shaped path yields low-fitness genotypes, accounting for the observed steep clines at hybrid zones.

Equity Financing and Investment in Technological Flexibility

We study the interactions between debt/equity financing and strategic (duopoly) technological flexibility choices of firms facing costly bankruptcy. We show that a firm's level of debt financing or financial hardship is an important determinant of the level and type of investment it chooses, either a less costly inflexible technology or a more expensive flexible technology. The level of financial hardship has a non-monotonic effect: as the level of equity financing increases, the choice of technology may switch and the level of investment may follow a bell-shaped or U-shaped path, depending on the differential investment cost, the bankruptcy cost, and whether or not the less costly technology is the best option for an all equity firm. We also show that the level of external financing (debt) may be used strategically in a non-cooperative tacitly collusive way to increase the expected profits of both firms, a firm may use debt as a commitment device to increase its own expected profit, and higher bankruptcy costs may be beneficial to both firms.

Reconfigurable Parts Feeding System Using Array of Vibrators

We propose a reconfigurable parts feeding system (RPFS) consisting of a large number of vibrators, each consisting of a vertical exciter having a piezoelectric element used as a drive source and a plate installed on the vertical exciter. The plate freely chooses a specific feed direction (forward and turn) by adjusting the thickness of the plate and the position of an elastic hinge. The RPSF features: (1) a variety of feed paths freely formed by adjusting plates on vertical exciters, and (2) positional adjustment for plates on vertical exciters automated using a robot to reduce time and cost. We analyzed the vibration of plates based on vibration modes of plates based on FEM analysis. Basic RPFS performance was evaluated in 3 feeding experiments, i.e., along an I-shaped feed path, along a U-shaped feed path, and with a feeding object larger than each plate, using an experimental RPFS.

The dynamic effects of general purpose technologies on Schumpeterian growth

General purpose technologies (GPTs) are drastic innovations characterized by pervasiveness in use and innovational complementarities. The dynamic effects of a GPT are analyzed within a quality-ladders model of scale-invariant Schumpeterian growth. The diffusion path of a GPT across a continuum of industries is governed by S-curve dynamics. The model generates a unique, saddle-path long-run equilibrium. Along the transition path, the measure of industries that adopt the new GPT increases, consumption per capita falls, and the interest rate rises. The growth rate of the stock market depends negatively on the rate of GPT diffusion and the magnitude of the GPT-ridden RD and positively on the rate of population growth. It also follows a U-shaped path during the diffusion process of the new GPT. Finally, the model generates transitional growth cycles of per capita GNP.

U or Inverted‐U? That Is the Question

Fields (The Economic Journal, vol. 103, 1993, pp. 1228–35) provides a forceful argument in favor of a U‐shaped path for inequality during a period of high‐income‐sector enlargement in a dual‐economy model. This paper explores the assumptions necessary to derive Fields’s controversial result and demonstrates that in fact a U‐shaped pattern is possible using the Atkinson index, but some bizarre assumptions about inequality aversion are required.

Subharmonic responses of ion-implanted arrays reflecting magnetostatic forward volume waves

A subharmonic response at twice a fundamental wavelength was observed by reflection of magnetostatic forward volume waves on 45° oblique incidence ion-implanted arrays. The waves were reflected by two nonperiodic arrays and traveled along a U-shaped path. Each array made of 25 bars with an average fundamental wavelength of 69 μm was implanted with 3×1015 11 B+ ions per cm2 at 150 keV. For such a dose the damaged propagation material was nonferrimagnetic and the subharmonic reflection is attributed to an energy storage consequence of the magnetic field distortion introduced by the crystalline-nonferrimagnetic material-interface corrugation. It vanished after an annealing at 620 °C without great degradation of the fundamental wavelength reflection level.

Trade with an exhaustible resource when demand reactions are lagged

This paper attempts to combine sluggish adjustments in demand with optimisation behaviour of resource exporting countries who invest their petrodollars in an imperfect capital market. An intertemporal competitive equilibrium is derived, in which a U-shaped path of the resource price can occur. A period of decreasing prices after an oil price shock can be explained without making use of the cartelisation hypothesis.

An Experimental Analysis of the Behaviour ofLittorina Littorea(L.) Under Natural Conditions and in the Laboratory

Winkles dwelling on horizontal surfaces orientate by means of a lightcompass reaction. As the tide recedes, most of the tracks in the sand are towards the sun but after a time each animal reverses its direction of crawling, so tracing out a roughly U-shaped path which leads it back, approximately, to its starting-point.When kept in an aquarium winkles tend to settle on the sides above the waterline and to become inactive. When stimulated, as by immersion, they crawl downwards, then horizontally and then upwards before settling above the waterline.Winkles collected from horizontal surfaces at first show no tendency to climb vertical surfaces in an aquarium. After a period which varies from a few hours up to 10 days they do climb the sides of the tank. Animals collected from vertical surfaces climb the sides of the aquarium at their first opportunity and then settle. It can be concluded that winkles have an inherent tendency to climb and settle in the head-up position on vertical or steeply sloping surfaces but that if this opportunity is denied them they become habituated to horizontal surfaces.The minimum angle to which winkles can react by gravitational responses is of the order of 10–20 degrees.In an aquarium starved winkles prolong their excursions below water when presented with suitable food but fully fed animals respond less strongly to the stimulus of immersion.Dark-adapted winkles from horizontal surfaces are at first positively phototactic, but after a time varying from 15 to 20 min, they become negatively phototactic. Tested with the ‘two-light’ experiment most animals disregard the second light (telotaxis).