Renormalization of Entanglement Entropy and the Gravitational Effective Action

The entanglement entropy associated with a spatial boundary in quantum field theory is UV divergent, with the leading term proportional to the area of the boundary. For a class of quantum states defined by a path integral, the Callan-Wilczek formula gives a geometrical definition of the entanglement entropy. We show that, for this class of quantum states, the entanglement entropy is rendered UV-finite by precisely the counterterms required to cancel the UV divergences in the gravitational effective action. In particular, the leading contribution to the entanglement entropy is given by the renormalized Bekenstein-Hawking formula, in accordance with a proposal of Susskind and Uglum. We show that the subleading UV-divergent terms in the entanglement entropy depend nontrivially on the quantum state. We compute new subleading terms in the entanglement entropy and find agreement with the Wald entropy formula for black hole spacetimes with bifurcate Killing horizons. We speculate that the entanglement entropy of an arbitrary spatial boundary may be a well-defined observable in quantum gravity.Comment: 26 pages, 2 figures. v2: minor corrections and clarification

Managerial Stock Ownership As A Corporate Control Device: When Is Enough, Enough?

It has long been accepted that managerial stock ownership, beyond some range of possible entrenchment, can be an effective means of aligning the interests of professional managers with those of a firm’s outside owners to the benefit of firm performance. In this paper, we offer evidence on the effectiveness of managerial stock ownership as a corporate control device by analyzing the behavior of 81 thrift institutions operating over the six-year period, 1989-1994. Based on the estimation of stochastic cost and profit frontiers, as well as other performance measures, our results suggest that managerial stock ownership provides an effective corporate control device. However, this device is only effective as managerial holdings surpass about 33% of outstanding shares for improvements in cost efficiency and about 40% for profit efficiency

The Determinants of Takeovers: Recent Evidence from U.S. Thrifts

This paper uses a two-step methodology to examine the relationship between managerial cost inefficiency and the takeover of U.S. thrifts during a period of market liberalization and widespread takeover activity, 1994 to 2000. In the first stage using stochastic cost frontiers, we estimate controllable managerial cost inefficiency scores for all stock firms operating each year in 1994 to 2000. In a second stage, we use these scores to examine correlates of takeovers, focusing on cost inefficiency. For takeovers by banks, we find a significant negative relationship between cost inefficiency and takeover, suggesting an exit of more cost efficient firms from the thrift industry during this period. However, takeovers by thrifts are associated with other characteristics

U.S. Muslims Concerned About Their Place in Society, but Continue to Believe in the American Dream

The early days of Donald Trump's presidency have been an anxious time for many Muslim Americans, according to a new Pew Research Center survey. Overall, Muslims in the United States perceive a lot of discrimination against their religious group, are leery of Trump and think their fellow Americans do not see Islam as part of mainstream U.S. society. At the same time, however, Muslim Americans express a persistent streak of optimism and positive feelings. Overwhelmingly, they say they are proud to be Americans, believe that hard work generally brings success in this country and are satisfied with the way things are going in their own lives – even if they are not satisfied with the direction of the country as a whole

Fast Monte Carlo Algorithms for Permutation Groups

AbstractWe introduce new, elementary Monte Carlo methods to speed up and greatly simplify the manipulation of permutation groups (given by a list of generators). The methods are of a combinatorial character, using only elementary group theory. The key idea is that under certain conditions, "random subproducts" of the generators successfully emulate truly random elements of a group. We achieve a nearly optimal O(n3 logcn) asymptotic running time for membership testing, where n is the size of the permutation domain. This is an improvement of two orders of magnitude compared to known elementary algorithms and one order of magnitude compared to algorithms which depend on heavy use of group theory. An even greater asymptotic speedup is achieved for normal closures, a key ingredient in group-theoretic computation, now constructible in Monte Carlo time O(n2 logcn), i.e., essentially linear time (as a function of the input length). Some of the new techniques are sufficiently general to allow polynomial-time implementations in the very general model of "black box groups" (group operations are performed by an oracle). In particular, the normal closure algorithm has a number of applications to matrix-group computation. It should be stressed that our randomized algorithms are not heuristic: the probability of error is guaranteed not to exceed a bound ϵ > 0, prescribed by the user. The cost of this requirement is a factor of |log ϵ| in the running time

Proximal Gastrojejunal Reconstruction after Pancreaticoduodenal Resection

Introduction. Reconstruction by proximal gastrojejunostomy, and distal biliary and pancreatic anastomoses is infrequently used after resection of the head of the pancreas because of fear of fistulas and cholangitis. Pancreaticoduodenectomy is being performed more frequently for cystic malignant and premalignant lesions. Because of this there is a need for endoscopic visualization and biopsy of the residual pancreatic duct, since multi-centricity is characteristic of some of these malignancies. Since endoscopic access of the bile duct and pancreatic duct is difficult and unsuccessful in 50–70% after B II or Roux Y reconstruction, we prospectively studied the merit and complications (early and late) of proximal gastrojejunal (PGJ) reconstruction after pancreaticoduodenal resection. Material and Methods. Thirty nine consecutive, non-radomized patients underwent pancreaticoduodenectomy and PGJ reconstruction over 14 mos. There were 21 males and 18 females. Results. 7 patients with IPMN have undergone repeat CT scanning for surveillance, with 3 requiring repeat EUS and ERCP. There were no technical difficulties accessing the pancreas or the pancreatic duct, supporting the PGJ reconstruction. Conclusion. Proximal gastrojejunal reconstruction following pancreaticoduodenal resection may be safely done with similar morbidity to traditional pancreaticojejunal reconstructions. PGJ reconstruction may be of greater value when direct visual access to the bile duct or pancreatic duct is necessary, and should be considered when doing resection for mucinous cysts or IPMN of the head of the pancreas

Managerial Stock Ownership As A Corporate Control Device: When Is Enough, Enough?

It has long been accepted that managerial stock ownership, beyond some range of possible entrenchment, can be an effective means of aligning the interests of professional managers with those of a firm’s outside owners to the benefit of firm performance. In this paper, we offer evidence on the effectiveness of managerial stock ownership as a corporate control device by analyzing the behavior of 81 thrift institutions operating over the six-year period, 1989-1994. Based on the estimation of stochastic cost and profit frontiers, as well as other performance measures, our results suggest that managerial stock ownership provides an effective corporate control device. However, this device is only effective as managerial holdings surpass about 33% of outstanding shares for improvements in cost efficiency and about 40% for profit efficiency

Conformal Tightness of Holographic Scaling in Black Hole Thermodynamics

The near-horizon conformal symmetry of nonextremal black holes is shown to be a mandatory ingredient for the holographic scaling of the scalar-field contribution to the black hole entropy. This conformal tightness is revealed by semiclassical first-principle scaling arguments through an analysis of the multiplicative factors in the entropy due to the radial and angular degrees of freedom associated with a scalar field. Specifically, the conformal SO(2,1) invariance of the radial degree of freedom conspires with the area proportionality of the angular momentum sums to yield a robust holographic outcome.Comment: 23 pages, 1 figure. v2 & v3: expanded explanations and proofs, references added, typos corrected; v3: published versio