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Chlorine monoxide (ClO) plays a key role in stratospheric ozone loss processes at midlatitudes. We present two balloonborne in situ measurements of ClO conducted in northern hemisphere midlatitudes during the period of the maximum of total inorganic chlorine loading in the atmosphere. Both ClO measurements were conducted on board the TRIPLE balloon payload, launched in November 1996 in Le´on, Spain, and in May 1999 in Aire sur l’Adour, France. For both flights a ClO daylight and night time vertical profile could be derived over an altitude range of approximately 15–31 km. ClO mixing ratios are compared to model simulations performed with the photochemical box model version of the Chemical Lagrangian Model of the Stratosphere (CLaMS). Simulations along 24-h backward trajectories were performed to study the diurnal variation of ClO in the midlatitude lower stratosphere. Model simulations for the flight launched in Aire sur l’Adour 1999 show a good agreement with the ClO measurements. For the flight launched in Le´on 1996, a similar good agreement is found, except at around ~ 650 K potential temperature (~26km altitude). However, a tendency is found that for solar zenith angles greater than 86°–87° the simulated ClO mixing ratios substantially overestimate measured ClO by approximately a factor of 2.5 or more for both flights. Therefore we conclude that no indication can be deduced from the presented ClO measurements that substantial uncertainties exist in midlatitude chlorine chemistry of the stratosphere. An exception is the situation at solar zenith angles greater than 86°–87° where model simulations substantial overestimate ClO observations.
Results are presented from a search for the decays D0 -> K min pi plus and D0 bar -> K plus pi min in a sample of 3.8x10^6 central Pb-Pb events collected with a beam energy of 158A GeV by NA49 at the CERN SPS. No signal is observed. An upper limit on D0 production is derived and compared to predictions from several models.
Particle production in central Pb+Pb collisions was studied with the NA49 large acceptance spectrometer at the CERN SPS at beam energies of 20, 30, 40, 80, and 158 GeV per nucleon. A change of the energy dependence is observed around 30A GeV for the yields of pions and strange particles as well as for the shapes of the transverse mass spectra. At present only a reaction scenario with onset of deconfinement is able to reproduce the measurements.
Despite a lot of re-structuring and many innovations in recent years, the securities transaction industry in the European Union is still a highly inefficient and inconsistently configured system for cross-border transactions. This paper analyzes the functions performed, the institutions involved and the parameters concerned that shape market and ownership structure in the industry. Of particular interest are microeconomic incentives of the main players that can be in contradiction to social welfare. We develop a framework and analyze three consistent systems for the securities transaction industry in the EU that offer superior efficiency than the current, inefficient arrangement. Some policy advice is given to select the 'best' system for the Single European Financial Market.
In recent years stock exchanges have been increasingly diversifying their operations into related business areas such as derivatives trading, post-trading services and software sales. This trend can be observed most notably among profit-oriented trading venues. While the pursuit for diversification is likely to be driven by the attractiveness of these investment opportunities, it is yet an open question whether certain integration activities are also efficient, both from a social welfare and from the exchanges' perspective. Academic contributions so far analyzed different business models primarily from the social welfare perspective, whereas there is only little literature considering their impact on the exchange itself. By employing a panel data set of 28 stock exchanges for the years 1999-2003 we seek to shed light on this topic by comparing the factor productivity of exchanges with different business models. Our findings suggest three conclusions: (1) Integration activity comes at the cost of increased operational complexity which in some cases outweigh the potential synergies between related activities and therefore leads to technical inefficiencies and lower productivity growth. (2) We find no evidence that vertical integration is more efficient and productive than other business models. This finding could contribute to the ongoing discussion about the merits of vertical integration from a social welfare perspective. (3) The existence of a strong in-house IT-competence seems to be beneficial to overcome.
Academic contributions on the demutualization of stock exchanges so far have been predominantly devoted to social welfare issues, whereas there is scarce empirical literature referring to the impact of a governance change on the exchange itself. While there is consensus that the case for demutualization is predominantly driven by the need to improve the exchange's competitiveness in a changing business environment, it remains unclear how different governance regimes actually affect stock exchange performance. Some authors propose that a public listing is the best suited governance arrangement to improve an exchange's competitiveness. By employing a panel data set of 28 stock exchanges for the years 1999-2003 we seek to shed light on this topic by comparing the efficiency and productivity of exchanges with differing governance arrangements. For this purpose we calculate in a first step individual efficiency and productivity values via DEA. In a second step we regress the derived values against variables that - amongst others - map the institutional arrangement of the exchanges in order to determine efficiency and productivity differences between (1) mutuals (2) demutualized but customer-owned exchanges and (3) publicly listed and thus at least partly outsider-owned exchanges. We find evidence that demutualized exchanges exhibit higher technical efficiency than mutuals. However, they perform relatively poor as far as productivity growth is concerned. Furthermore, we find no evidence that publicly listed exchanges possess higher efficiency and productivity values than demutualized exchanges with a customer-dominated structure. We conclude that the merits of outside ownership lie possibly in other areas such as solving conflicts of interest between too heterogeneous members.
It is widely believed that the ideal board in corporations is composed almost entirely of independent (outside) directors. In contrast, this paper shows that some lack of board independence can be in the interest of shareholders. This follows because a lack of board independence serves as a substitute for commitment. Boards that are dependent on the incumbent CEO adopt a less aggressive CEO replacement rule than independent boards. While this behavior is inefficient ex post, it has positive ex ante incentive effects. The model suggests that independent boards (dependent boards) are most valuable to shareholders if the problem of providing appropriate incentives to the CEO is weak (severe).
Wider participation in stockholding is often presumed to reduce wealth inequality. We measure and decompose changes in US wealth inequality between 1989 and 2001, a period of considerable spread of equity culture. Inequality in equity wealth is found to be important for net wealth inequality, despite equity's limited share. Our findings show that reduced wealth inequality is not a necessary outcome of the spread of equity culture. We estimate contributions of stockholder characteristics to levels and inequality in equity holdings, and we distinguish changes in configuration of the stockholder pool from changes in the influence of given characteristics. Our estimates imply that both the 1989 and the 2001 stockholder pools would have produced higher equity holdings in 1998 than were actually observed for 1998 stockholders. This arises from differences both in optimal holdings and in financial attitudes and practices, suggesting a dilution effect of the boom followed by a cleansing effect of the downturn. Cumulative gains and losses in stockholding are shown to be significantly influenced by length of household investment horizon and portfolio breadth but, controlling for those, use of professional advice is either insignificant or counterproductive. JEL Classification: E21, G11
We argue that the shape of the system-size dependence of strangeness production in nucleus-nucleus collisions can be understood in a picture that is based on the formation of clusters of overlapping strings. A string percolation model combined with a statistical description of the hadronization yields a quantitative agreement with the data at sqrt s_NN = 17.3 GeV. The model is also applied to RHIC energies.