Boolean Functions, Projection Operators and Quantum Error Correcting Codes

This paper describes a fundamental correspondence between Boolean functions and projection operators in Hilbert space. The correspondence is widely applicable, and it is used in this paper to provide a common mathematical framework for the design of both additive and non-additive quantum error correcting codes. The new framework leads to the construction of a variety of codes including an infinite class of codes that extend the original ((5,6,2)) code found by Rains [21]. It also extends to operator quantum error correcting codes.Comment: Submitted to IEEE Transactions on Information Theory, October 2006, to appear in IEEE Transactions on Information Theory, 200

Flow with PMD: Past and Future

Measurements of azimuthal distribution of inclusive photons using the fine granularity preshower photon multiplicity detector (PMD) at CERN SPS are used to obtain anisotropy in the azimuthal distributions. These results are used to estimate the anisotropy in the neutral pion distributions. The results are compared with results of charged particle data, both for first order and second order anisotropy. Assuming the same anisotropy for charged and neutral pions, the anisotropy in photons is estimated and compared with the measured anisotropy. The effect of neutral pion decay on the correlation between the first order and the second order event plane is also discussed. Data from PMD can also be used to estimate the reaction plane for studying any anisotropy in particle emission characteristics in the ALICE experiment at the Large Hadron Collider. In particular, we show that using the event plane from the PMD, it will be possible to measure the anisotropy in Jpsi absorption (if any) in the ALICE experiment.Comment: Invited talk in the Fourth International Conference on the Physics and Astrophysics of Quark Gluon Plasma, 26-30 Nov.2001, Jaipur, Indi

The Other Side of the Tradeoff: The Impact of Risk on Executive Compensation

The principal-agent model of executive compensation is of central importance to the modern theory of the firm and corporate governance, yet the existing empirical evidence supporting it is quite weak. The key predication of the model is that the executive's pay-performance sensitivity is decreasing in the variance of the firm's performance. We demonstrate strong empirical confirmation of this prediction using a comprehensive sample of executives at large corporations. In general, the pay-performance sensitivity for executives at firms with the least volatile stock prices is an order of magnitude greater than the pay-performance sensitivity for executives at firms with the most volatile stock prices. This result holds for both chief executive officers and for other highly compensated executives. We further show that estimates of the pay-performance sensitivity that do not explicitly account for the effect of the variance of firm performance are biased toward zero. We also test for relative performance evaluation of executives against the performance of other firms. We find little support for the relative performance evaluation model. Our findings suggest that executive compensation contracts incorporate the benefits of risk-sharing but do not incorporate the potential informational advantages of relative performance evaluation.

Executive Compensation, Strategic Competition, and Relative Performance Evaluation: Theory and Evidence

We argue that strategic interactions between firms in an oligopoly can explain the puzzling lack of high-powered incentives in executive compensation contracts written by shareholders whose objective is to maximize the value of their shares. We derive the optimal compensation contracts for managers and demonstrate that the use of high-powered incentives will be limited by the need to soften product market competition. In particular, when managers can be compensated based on their own and their rivals' performance, we show that there will be an inverse relationship between the magnitude of high-powered incentives and the degree of competition in the industry. More competitive industries are characterized by weaker pay-performance incentives. Empirically, we find strong evidence of this inverse relationship in the compensation of executives in the United States. Our econometric results are not consistent with alternative theories of the effect of competition on executive compensation. We conclude that strategic considerations can preclude the use of high-powered incentives, in contrast to the predictions of the standard principal-agent model.

Event-by-Event Search for Charged Neutral Fluctuations in Pb - Pb Collisions at 158-A-GeV

Results from the analysis of data obtained from the WA98 experiment at the CERN SPS have been presented. Some events have been filtered which show photon excess in limited $\eta-\phi$ zones within the overlap region of the charged particle and photon multiplicity detectors.Comment: 6 pages, 4 figure

PriPeARL: A Framework for Privacy-Preserving Analytics and Reporting at LinkedIn

Preserving privacy of users is a key requirement of web-scale analytics and reporting applications, and has witnessed a renewed focus in light of recent data breaches and new regulations such as GDPR. We focus on the problem of computing robust, reliable analytics in a privacy-preserving manner, while satisfying product requirements. We present PriPeARL, a framework for privacy-preserving analytics and reporting, inspired by differential privacy. We describe the overall design and architecture, and the key modeling components, focusing on the unique challenges associated with privacy, coverage, utility, and consistency. We perform an experimental study in the context of ads analytics and reporting at LinkedIn, thereby demonstrating the tradeoffs between privacy and utility needs, and the applicability of privacy-preserving mechanisms to real-world data. We also highlight the lessons learned from the production deployment of our system at LinkedIn.Comment: Conference information: ACM International Conference on Information and Knowledge Management (CIKM 2018

Empire-Builders and Shirkers: Investment, Firm Performance, and Managerial Incentives

Do firms systematically over- or underinvest as a result of agency problems? We develop a contracting model between shareholders and managers in which managers have private benefits or private costs of investment. Managers overinvest when they have private benefits and underinvest when they have private costs. Optimal incentive contracts mitigate the over- or underinvestment problem. We derive comparative static predictions for the equilibrium relationships between incentives from compensation, investment, and firm performance for both cases. The relationship between firm performance and managerial incentives, in isolation, is insufficient to identify whether managers have private benefits or private costs of investment. In order to identify whether managers have private benefits or costs, we estimate the joint relationships between incentives and firm performance and between incentives and investment. Our empirical results show that both firm performance and investment are increasing in managerial incentives. These results are consistent with managers having private costs of investment. We find no support for overinvestment based on private benefits.

Performance Incentives Within Firms: The Effect of Managerial Responsibility

Empirical research on executive compensation has focused almost exclusively on the incentives provided to chief executive officers. However, firms are run by teams of managers, and a theory of the firm should also explain the distribution of incentives and responsibilities for other members of the top management team. An extension of the standard principal-agent model to allow for multiple signals of effort predicts that executives who have other, more precise signals of their effort than firm performance will have compensation that is less sensitive to the overall performance of the firm. We test this prediction in a comprehensive panel dataset of executives at large corporations by comparing executives with explicit divisional responsibilities to those with broad oversight authority over the firm and to CEOs. Controlling for executive fixed effects and the level of compensation, we find that CEOs have pay-performance incentives that are $5.85 per thousand dollar increase in shareholder wealth higher than the pay-performance incentives of executives with divisional responsibility. Executives with oversight authority have pay-performance incentives that are$1.26 per thousand higher than those of executives with divisional responsibility. The aggregate pay-performance sensitivity of the top management team is quite substantial, at $30.24 per thousand dollar increase in shareholder wealth for the median firm in our sample. Our work sheds light on the alignment of responsibility and incentives within firms and suggests that the principal-agent model provides an appropriate characterization of the internal organization of the firm.