Tuning the range of spatial coupling in electrochemical systems: From local via nonlocal to global coupling

A specific feature of pattern formation in electrochemical systems is the occurrence of accelerated fronts; they can be attributed to long-range spatial coupling. In this paper we demonstrate that different coupling functions can be realized by tuning easily accessible parameters: The range of the coupling crucially depends on the length scales of the system, and the strength of the coupling is proportional to the conductivity of the electrolyte. Simulations in the bistable regime are presented which illustrate how the front behavior changes qualitatively when length scales or conductivity are varied

The Effect of Block Ownership on Future Firm Value and Performance

This paper examines the performance of the investment decisions of block owners. The block ownership data is obtained from Dlugosz, Fahlenbrach, Gompers, and Metrick (2006). We find that firm valuation (measured by Tobin's Q), operating performance (measured by changes in return on assets) and stock performance (measured by excess buy and hold returns) are positively and significantly related to the previous years' level of block ownership both in terms of the size of the ownership and the number of blockholders. Our results are robust to endogeneity concerns. Regarding whether a specific blockholder is an “insider” or an “outsider” to the firm, we find that the ownership of “outside” blockholders is a key determinant in explaining future firm performance. Note though that this category makes up about two-thirds of the aggregate amount of blockholding in Dlugosz et al. (2006) database, and also includes all blockholders not classified in other categories. In general, we attribute the superior performance to the presence of more blockholders. We also find an inverse association between the volatility in blockownership and the ex-post firm performance measures

Stock return comovement around the Dow Jones Islamic Market World Index revisions

We examine patterns of comovement in stock returns around the Dow Jones Islamic Market World Index (DJIMWI) quarterly revision events. Our analysis is based on a sample of 8250 companies from eighteen countries during the period May 1999–June 2012. We find that a stock’s comovement with the DJIMWI increases when it joins and decreases when it leaves the index. We also find that the comovement of newly added (deleted) stocks with the existing DJIMWI constituents increases (declines) during periods of high trading activity and during the month of Ramadan. Further tests reveal that changes in the fundamentals have no impact on the comovements of added and deleted stocks. Overall, our results indicate that stock returns respond to the emotional state of investors around information-free events

Breathing Current Domains in Globally Coupled Electrochemical Systems: A Comparison with a Semiconductor Model

Spatio-temporal bifurcations and complex dynamics in globally coupled intrinsically bistable electrochemical systems with an S-shaped current-voltage characteristic under galvanostatic control are studied theoretically on a one-dimensional domain. The results are compared with the dynamics and the bifurcation scenarios occurring in a closely related model which describes pattern formation in semiconductors. Under galvanostatic control both systems are unstable with respect to the formation of stationary large amplitude current domains. The current domains as well as the homogeneous steady state exhibit oscillatory instabilities for slow dynamics of the potential drop across the double layer, or across the semiconductor device, respectively. The interplay of the different instabilities leads to complex spatio-temporal behavior. We find breathing current domains and chaotic spatio-temporal dynamics in the electrochemical system. Comparing these findings with the results obtained earlier for the semiconductor system, we outline bifurcation scenarios leading to complex dynamics in globally coupled bistable systems with subcritical spatial bifurcations.Comment: 13 pages, 11 figures, 70 references, RevTex4 accepted by PRE http://pre.aps.or

L’Utilisation de L’Alliage CoCrMo En Biomécanique (cas de prothèse discal)

Les paramètres pour la production de la métallurgie des poudres classique d'un alliage CoCrMo pour les prothèses orthopédiques sont déterminés. Avec l'application de ces paramètres, un alliage ayant une densité à l’état brute, une faible porosité après frittage, la dureté considérable et comportement passif avec une résistance de frottement imporante

Underwriters' allocation with and without discretionary power: Evidence from the Hong Kong IPO market

This study uses a unique and extensive data set from the Hong Kong IPO market to examine the theory of adverse selection under two distinct regulatory regimes in relation to underwriters' discretionary power in IPO share allocation. Consistent with Rock's (1986) theory of adverse selection in the IPO market, we show that, prior to the introduction of the clawback provision; retail (uninformed) investors were allocated more of the overpriced offerings and less of the underpriced issues. However, after the provision is implemented, retail investors have been allocated significantly more of the underpriced offerings and less of the overpriced ones. Overall, we find that allocation-adjusted initial returns for the retail investors are lower (higher) than the risk-free rate pre- (post-) clawback provision. These findings imply that the mandatory clawback provision has enhanced the fairness in IPO share allocations among different investor groups and has reduced the winner's curse in the IPO market

A fitter code for Deep Virtual Compton Scattering and Generalized Parton Distributions

We have developped a fitting code based on the leading-twist handbag Deep Virtual Compton Scattering (DVCS) amplitude in order to extract the Generalized Parton Distributions (GPD) information from DVCS observables in the valence region. In a first stage, with simulations and pseudo-data, we show that the full GPD information can be recovered from experimental data if enough observables are measured. If only part of these observables are measured, valuable information can still be extracted, certain observables being particularly sensitive to certain GPDs. In a second stage, we make a practical application of this code to the recent DVCS Jefferson Lab Hall A data from which we can extract numerical constraints for the two $H$ GPD Compton Form Factors.Comment: 15 pages, 8 figure

Rosenbluth Separation of the π0 Electroproduction Cross Section Off the Neutron

We report the first longitudinal-transverse separation of the deeply virtual exclusive π0 electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions dσL/dt, dσT/dt, dσLT/dt, and dσTT/dt are extracted as a function of the momentum transfer to the recoil system at Q2 = 1.75 GeV2 and xB = 0.36. The ed -\u3e edπ0 cross sections are found compatible with the small values expected from theoretical models. The en -\u3e enπ0 cross sections show a dominance from the response to transversely polarized photons, and are in good agreement with calculations based on the transversity generalized parton distributions of the nucleon. By combining these results with previous measurements of π0 electroproduction off the proton, we present a flavor decomposition of the u and d quark contributions to the cross section

Scaling Tests of the Cross Section for Deeply Virtual Compton Scattering

We present the first measurements of the ep → epγ cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region. The Q2 dependence (from 1.5 to 2.3 GeV2) of the helicity-dependent cross section indicates the twist-2 dominance of DVCS, proving that generalized parton distributions (GPDs) are accessible to experiment at moderate Q2. The helicity-independent cross section is also measured at Q2=2.3 GeV2. We present the first model-independent measurement of linear combinations of GPDs and GPD integrals up to the twist-3 approximation

Generalized Parton Distributions from Hadronic Observables: Non-Zero Skewness

We propose a physically motivated parametrization for the unpolarized generalized parton distributions, H and E, valid at both zero and non-zero values of the skewness variable, \zeta. Our approach follows a previous detailed study of the \zeta=0 case where H and E were determined using constraints from simultaneous fits of the experimental data on both the nucleon elastic form factors and the deep inelastic structure functions in the non singlet sector. Additional constraints at \zeta \neq 0 are provided by lattice calculations of the higher moments of generalized parton distributions. We illustrate a method for extracting generalized parton distributions from lattice moments based on a reconstruction using sets of orthogonal polynomials. The inclusion in our fit of data on Deeply Virtual Compton Scattering is also discussed. Our method provides a step towards a model independent extraction of generalized distributions from the data. It also provides an alternative to double distributions based phenomenological models in that we are able to satisfy the polynomiality condition by construction, using a combination of experimental data and lattice, without resorting to any specific mathematical construct.Comment: 29 pages, 8 figures; added references, changed text in several place