Positron production in crossed beams of bare uranium nuclei

Positron creation in crossed-beam collisions of high-energy, fully stripped heavy ions is investigated within the coupled-channel formalism. In comparison with fixed-target collisions of highly stripped heavy-ion projectiles positron production probabilities are enhanced by more than one order of magnitude. The increase results from the possibility to excite electrons from the negative energy continuum into all bound states. The positron spectrum is shifted towards higher energies because of the absence of electron screening. Rutherford scattering as well as nuclear collisions with time delay are investigated. We also discuss the filling of empty bound states by electrons from pair-production processes

Electron emission and positron production in deep inelastic heavy-ion reactions

Atomic excitations are used to obtain information on the course of a nuclear reaction. Employing a semiclassical picture we calculate the emission of δ electrons and positrons in deep inelastic nuclear reactions for the example of U+U collisions incorporating nuclear trajectories resulting from two different nuclear friction models. The emission spectra exhibit characteristic deviations from those expected for elastic Coulomb scattering. The theoretical probabilities are compared with recent experimental data by Backe et al. A simple model is used to estimate the influence of a threebody breakup of the compound system upon atomic excitations

Strategic Delegation in Experimental Markets

In this experiment, we analyze strategic delegation in a Cournot duopoly. Owners can choose among two different contracts which determine their managers' salaries. One contract simply gives managers incentives to maximize firm profits, while the second contract gives an additional sales bonus. Although theory predicts the second contract to be chosen, it is only rarely chosen in the experimental markets. This behavior is rational given that managers do not play according to the subgame perfect equilibrium prediction when asymmetric contracts are given.Strategic delegation, managerial incentives, experimental economics

To commit or not to commit: Endogenous timing in experimental duopoly markets

In this paper, we experimentally investigate the extended game with action commitment of Hamilton and Slutsky (1990). In their duopoly game, firms can choose their quantities in one of two periods before the market clears. If a firm commits to a quantity in period 1 it does not know whether the other firm also commits early. By waiting until period 2, a firm can observe the other firm's period 1 action. Hamilton and Slutsky predict the emergence of endogenous Stackelberg leadership. Our data, however, does not confirm the theory. While Stackelberg equilibria are extremely rare we often observe endogenous Cournot outcomes and sometimes collusive play. This is partly driven by the fact that endogenous Stackelberg followers learn to behave in a reciprocal fashion over time, i.e., they learn to reward cooperation and to punish exploitation.duoploly, endogenous timing, experimental economics

Output Commitment through Product Bundling: Experimental Evidence

We analyze the impact of product bundling in experimental markets. A firm has monopoly power in one market but faces competition by a second firm in another market. We compare treatments where the monopolist can bundle its two products to treatments where it cannot, and we contrast simultaneous and sequential order of moves. Our data indicate support for the theory of product bundling, even though substantial payoff differences between players exist. With bundling and simultaneous moves, the monopolist offers the predicted number of units. When the monopolist is the Stackelberg leader, the predicted equilibrium is better attained with bundling although in theory bundling should not make a difference here. In sum: bundling works as a commitment device that enables the transfer of market power from one market to another.

DIGITAL CONVERGENCE: EXAMINING THE DISSOLUTION OF INDUSTRIAL AND TECHNOLOGICAL BOUNDARIES

Digital convergence is frequently discussed in research. The concept of convergence describes how formerly separate areas are increasingly merging. So far, however, we have only a rudimentary understanding of digital convergence for several reasons. First, digital convergence is not clearly conceptualized and used differently across contexts. Second, we have little insight into what is converging and at what pace. We conceptualize digital convergence by arguing that its sociotechnical nature requires jointly considering technical and social aspects. Our analysis of a longitudinal patent data set covering 31 years and 677,045 patents from 124 industries shows that (1) industry boundaries defined by the Standard Industrial Classification (SIC) are dissolving as companies interact with technological knowledge outside their industrial boundaries. (2) Specific technology classes defined in the International Patent Classification (IPC) increasingly cite - and converge with - other technology classes. We close by highlighting promising avenues for future research on digital convergence

Randomized clinical trial evaluating the effect of bandaging on the healing of sole ulcers in dairy cattle

This randomized clinical trial investigated the effect of bandaging on 56 uncomplicated sole ulcers (SU) among a sample of 52 dairy cows. Following therapeutic hoof trimming and povidone-iodine treatment, all cows received a wooden block on the unaffected claw and were randomly assigned into either a bandaged or non-bandaged group. The bandaging process was standardized and applied by the same veterinarian. Wound size and locomotion were measured weekly. Overall, 19 of 32 SU (59.4%) in the non-bandaged group were healed at week 4 compared to 7 of 24 ulcers (29.2%) in the bandaged group. Healing was significantly higher for non-bandaged than bandaged SU (P = 0.024). Bandaging had no effect on locomotion (P = 0.9). Cows with a lower locomotion (Sprecher 1 + 2) had significantly smaller lesion sizes (median lesion size, 0.5 cm², IQR = 0.21 to 0.92 cm²) than animals with locomotion score 3–5 (median lesion size, 0.9 cm², IQR = 0.42 to 1.81 cm²; P < 0.001). A multivariate cox proportional hazard regression indicated that bandaging and parity had a significant effect on healing. Specifically, bandaged SU had a significantly lower hazard ratio (HR) to cure compared to non-bandaged SU (HR = 0.32; P = 0.01; 95% CI = 0.13 to 0.78). Furthermore, cows with parity ≥3 had a significantly higher HR to cure compared to cows in their first lactation (HR = 2.73; P = 0.025; 95% CI = 1.14 to 6.56)