Abstract – A study was initiated in 1993 to evaluate the potential effects of both above- and below-groundcompetition exclusion on yellow
birch (Betula alleghaniensis Britton), sugar maple (Acer saccharum Marsh.) and American beech (Fagus grandifolia Ehrh.) sapling growth along an understory light gradient ranging from 3% to 50% of full sunlight. We compared four different growth variables between a control and a treatment (trenching and manual removal of nearby vegetation). Height growth, diameter growth, height over stem diameter ratio, and crown area varied with light availability in all three species, whereas trenching treatment had no significant effect. Our results show that light is the main factor affecting understory sapling growth following a selection cut in this northern hardwood forest, at least up to 50% full sunlight. The unresponsiveness of these three species to below-groundcompetition is discussed in relation to a literature review in which both soil richness and species functional ecology are considered.
In order to more fully explore gains from trade and eﬃciency under monopolistic competi- tion, we must depart from the standard CES model. Doing so, however, has long been diﬃcult since variable elasticity of substitution (henceforth, VES) models have “not proved tractable, and from Dixit and Norman (1980) and Krugman (1980) onwards, most writers have used the CES speciﬁcation” (Neary, 2004, p.177). Building on the new general equilibrium model of monopolistic competition by Behrens and Murata (2007), we present a simple VES model of in- ternational trade featuring pro-competitive eﬀects (i.e., proﬁt-maximizing prices are decreasing in the mass of competing ﬁrms) and a competitive limit (i.e., proﬁt-maximizing prices converge to marginal costs when the mass of competing ﬁrms becomes arbitrarily large). Within this framework, we investigate the impact of trade on welfare and eﬃciency.
The recent implementation of the NSM Reg. and MiFID directive in the USA and Europe aim at fostering competition to decrease transaction costs, increase liquidity, and lower the cost of capital. However, competition among securities markets is a complex phenomenon since the market for trading services is embedded in the market for securities. Changes in the competitive regime determine sizeable redistribution of the profits from trading among market operators by shifting traded volumes from one venue to another. This suggests to adopt a political economy approach to explain changes in the competitive regimes. While competition could be beneficial for the trading services market and decrease explicit transaction costs such as commissions, it could harm the market for securities because of informational issues and then increase implicit transaction costs like spreads. Research particularly questions the effects of dark fragmentation The French regulatory reforms of 1893 and 1898 contribute to understanding these issues. They represent a unique natural experiment because they took place within a short period and affected markets located in the same financial center. We identified three regimes of competition between the transparent Parquet and the dark OTC-like Coulisse: i) a regime of “illegal” competition before 1893, when the Coulisse traded listed securities in violation of the Parquet’s legal monopoly; ii) a regime of free competition, between 1893 and 1898, when the government recognized Coulisse’s transactions on Parquet’s listed securities through a fiscal law; iii) a regime of strict monopoly granted to the Parquet after 1898, when a new fiscal law prevented the Coulisse from trading listed securities.
Furthermore, unlike the new trade theory, where more similar countries engage in more intra- industry trade, we show that countries become more similar due to trade, thus suggesting circular causation between similarity and intra-industry trade. Second, despite intersectoral heterogeneity, we establish the efficiency result, namely that intersectoral distortions are elim- inated as the population gets arbitrarily large in the integrated economy, while losses from intrasectoral distortions vanish in the limit as in the single-sector case. Finally, when either of the two sectors is nontraded, trade induces domestic exit, or a variety loss in the nontraded sector. Since the variety loss in the nontraded sector is not compensated by import varieties, this result suggests an important welfare implication: monopolistic competition models that abstract from nontraded varieties may overestimate gains from trade.
The Commission rejected this claim by stating that a
“measure may amount to a misuse of powers only if it appears, on the basis of objective, relevant and consistent factors, to have been taken with the exclusive purpose, or at any rate the main purpose, of achieving an end other than that stated or evading a procedure specifically prescribed by the Treaty for dealing with the circumstances of the case.” 44 These examples are a clear reminder that the role of competition authorities is not to regulate a sector or create a level playing field, but to prohibit breaches of competition rules and adopt (infringement decision) or accept (commitments decision) remedies that directly address the specific competition concerns it has identified.
atmosphere blocks most of the electromagnetic spectrum. These problems can be partially
alleviated by putting our observatories on the tops of carefully chosen mountains and high plateaux. It is interesting that one of the main arguments for putting telescopes in space has been partially overcome through technical innovations at ground level. A recent development now used at the Canada France Hawaii Telescope and others is “adaptive optics”. A thin, computer-deformable mirror is used to undo the distortions caused by the atmosphere. The basic principle is simple; the technology to do it is complex. So far it looks as though ground and space-based instruments will not replace each other, but their expanding capabilities will together help us to study the puzzles with which the universe is filled.
2. Assessing market power
A firm may enjoy a large market share either because it faces no competition or because it is more efficient than its competitors. In both cases, profitability is regarded as an element belonging to the bundle of indicators of market power. But, in markets driven by innovation, high ex-post returns on investment do not reveal anything about market power. Indeed, if such returns were unachievable, no one would take part in the race. The relevant criterion is expected return. This datum, however, is not easily calculable or straightforward to interpret. It is true of course that in mature industries as well, expected earnings rather past earnings are what matters. However, in the latter industries it is far more likely that the assets that made it possible to obtain these earnings in the past will not suddenly and thoroughly become obsolete in the near future. Therefore, looking backwards in order to gain an appreciation of future profits including profits from monopoly power is more revealing in a mature industry than in an innovative industry. When dealing with the latter one must also be careful to insure that the inferences about monopoly power drawn from profitability measures are adjusted for risk.
AlGaN/GaN HEMTs are very promising candidates for high frequency applications with high power and low noise, such as microwave and millimeter wave communica- tions, imaging and radars [ 1 ]. With the high ﬁeld strength oﬀered by GaN and the high mobility of the two dimen- sional electron gas (2DEG) in the HEMT, this device can reach high breakdown voltage with low ON-state resis- tance and high switching frequency, surpassing the limi- tation of conventional silicon devices. In the conventional HEMT, the triangular well, formed at AlGaN/GaN inter- face, is below the Fermi level at equilibrium. This makes the channel populated with electrons at zero gate voltage, hence making the HEMT normally-on. However, for power switching applications, normally-oﬀ operation is strongly required [ 2 ]. In order to achieve normally-oﬀ operation, the triangular well must be lifted above the Fermi level. Several structures have been proposed for the realization of normally-oﬀ AlGaN/GaN HEMTs, such as the recessed gate structures [ 3 ], ﬂuorine ion treatment [ 4 ], PN junction
the HC2(T) line (high-field result). The M(T, H) functional is not given explicitly.
Below Tc, Cho et al.  have observed in a Bi- 2212 single crystal surprising scalings M(T, H)/ M(T’, H) versus T and M(T, H)/M( T, H') versus H where (T’, H') is an arbitrary point in the reversible domain. They conclude that M(T, H) can be written as M( T, H) = f(T)g(H) and find that HC2 is quasi temperature independent in this temperature range.
Lastly, the taste for competing might change depending on whether one is part of a team or alone. NV found that, after controlling for differences in overconfidence, risk, ambiguity and feedback aversion, the gender gap in tournament entry was not entirely accounted for. They label the residual explanation as a gender dif- ference in the taste for performing in a competitive environment. The fact that the tournament is no longer an individual one could have a different impact on men’s and women’s thrill or fear of competition. Indeed, a literature interested in gender differences in economic decisions (Eckel and Grossman, 1998, 2001, 2008, Ortmann and Tichy, 1999) finds that women tend to be more socially-oriented and less individually-oriented than men as well as more cooperative and less selfish. If team competition succeeds in wiping out the gender gap in the taste for competition, it could show that institutional changes could be successful in making men and women equally willing to compete. The following subsection presents the Tasks the participants had to go through and explains how they allow one to control for the effects listed in the present subsection.