149 research outputs found
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 âinsiderâ or an âoutsiderâ to the firm, we find that the ownership of âoutsideâ 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 1999âJune 2012. We find that a stockâs 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
LâUtilisation de LâAlliage CoCrMo En BiomĂ©canique (cas de prothĂšse discal)
Les paramĂštres pour la production de la mĂ©tallurgie des poudres classique d'un alliage CoCrMo pour les prothĂšses orthopĂ©diques sont dĂ©terminĂ©s. Avec l'application de ces paramĂštres, un alliage ayant une densitĂ© Ă lâĂ©tat brute, une faible porositĂ© aprĂšs frittage, la duretĂ© considĂ©rable et comportement passif avec une rĂ©sistance 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 GPD Compton Form
Factors.Comment: 15 pages, 8 figure
Rosenbluth Separation of the Ï0 Electroproduction Cross Section Off the Neutron
We report the first longitudinal-transverse separation of the deeply virtual exclusive Ï0 electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions dÏL/dt, dÏT/dt, dÏLT/dt, and dÏTT/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 edÏ0 cross sections are found compatible with the small values expected from theoretical models. The en -\u3e enÏ0 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 Ï0 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 â epÎł 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
- âŠ