Relationship between spin squeezing and single-particle coherence in two-component Bose-Einstein condensates with Josephson coupling

We investigate spin squeezing of a two-mode boson system with a Josephson coupling. An exact relation between the squeezing and the single-particle coherence at the maximal-squeezing time is discovered, which provides a more direct way to measure the squeezing by readout the coherence in atomic interference experiments. We prove explicitly that the strongest squeezing is along the $J_z$ axis, indicating the appearance of atom number-squeezed state. Power laws of the strongest squeezing and the optimal coupling with particle number $N$ are obtained based upon a wide range of numerical simulations.Comment: 4 figures, revtex4, new refs. are adde

A flexible mandatory access control policy for XML databases

A flexible mandatory access control policy (MAC) for XML databases is presented in this paper. The label type and label access policy can be defined according to the requirements of applications. In order to preserve the integrity of data in XML databases, a constraint between a read access rule and a write access rule in label access policy is introduced. Rules for label assignment and propagation are proposed to alleviate the workload of label assignment. Also, a solution for resolving conflicts of label assignments is proposed. At last, operations for implementation of the MAC policy in a XML database are illustrated

A practical mandatory access control model for XML databases

A practical mandatory access control (MAC) model for XML databases is presented in this paper. The label type and label access policy can be defined according to the requirements of different applications. In order to preserve the integrity of data in XML databases, a constraint between a read-access rule and a write-access rule in label access policy is introduced. Rules for label assignment and propagation are presented to alleviate the workload of label assignments. Furthermore, a solution for resolving conflicts in label assignments is proposed. Rules for update-related operations, rules for exceptional privileges of ordinary users and the administrator are also proposed to preserve the security of operations in XML databases. The MAC model, we proposed in this study, has been implemented in an XML database. Test results demonstrated that our approach provides rational and scalable performance

Corruption and Cross-Border Investment: Firm-Level Evidence

This paper studies the impact of corruption on inward foreign direct investment using a unique firm-level data set. It examines two effects of corruption simultaneously: a reduction in the volume of foreign investment and a shift in the ownership structure. Corruption makes local bureaucracy less transparent and hence acts as a tax on foreign investors. Moreover, corruption affects the decision to take on a local partner. On the one hand, corruption increases the value of using a local partner to cut through the bureaucratic maze. On the other hand, corruption decreases the effective protection of investor’s intangible assets and lowers the probability that disputes between foreign and domestic partners will be adjudicated fairly, which reduces the value of having a local partner. The importance of protecting intangible assets increases with investor’s technological sophistication, which tilts the preference away from joint ventures in a corrupt country. Empirical evidence shows that corruption reduces inward FDI and shifts the ownership structure towards joint ventures. Technologically more advanced firms are found to be less likely to engage in joint ventures.http://deepblue.lib.umich.edu/bitstream/2027.42/39879/3/wp494.pd

Event-by-event simulation of the Hanbury Brown-Twiss experiment with coherent light

We present a computer simulation model for the Hanbury Brown-Twiss experiment that is entirely particle-based and reproduces the results of wave theory. The model is solely based on experimental facts, satisfies Einstein's criterion of local causality and does not require knowledge of the solution of a wave equation. The simulation model is fully consistent with earlier work and provides another demonstration that it is possible to give a particle-only description of wave phenomena, rendering the concept of wave-particle duality superfluous.Comment: Submitted to Commmun. Comput. Phy