Unitary Quantum Physics with Time-Space Noncommutativity

In this work quantum physics in noncommutative spacetime is developed. It is based on the work of Doplicher et al. which allows for time-space noncommutativity. The Moyal plane is treated in detail. In the context of noncommutative quantum mechanics, some important points are explored, such as the formal construction of the theory, symmetries, causality, simultaneity and observables. The dynamics generated by a noncommutative Schrodinger equation is studied. We prove in particular the following: suppose the Hamiltonian of a quantum mechanical particle on spacetime has no explicit time dependence, and the spatial coordinates commute in its noncommutative form (the only noncommutativity being between time and a space coordinate). Then the commutative and noncommutative versions of the Hamiltonian have identical spectra.Comment: 18 pages, published versio

Financial Globalization and Economic Policies

We review the large literature on various economic policies that could help developing economies effectively manage the process of financial globalization. Our central findings indicate that policies promoting financial sector development, institutional quality and trade openness appear to help developing countries derive the benefits of globalization. Similarly, sound macroeconomic policies are an important prerequisite for ensuring that financial integration is beneficial. However, our analysis also suggests that the relationship between financial integration and economic policies is a complex one and that there are unavoidable tensions inherent in evaluating the risks and benefits associated with financial globalization. In light of these tensions, structural and macroeconomic policies often need to be tailored to take into account country specific circumstances to improve the risk-benefit tradeoffs of financial integration. Ultimately, it is essential to see financial integration not just as an isolated policy goal but as part of a broader package of reforms and supportive macroeconomic policies

WiFlex: Multi-Channel Cooperative Protocols for Heterogeneous Wireless Devices

protocols create complex coexistence and connectivity problems. If the same trend continues, similar interference and performance problems will continue to exist in future unlicensed bands. As new unlicensed bands open up, one can take a different approach to spectrum sharing. Instead of proposing a new MAC protocol for each type of application, we propose a family of parameterized MAC protocols called WiFlex that can tailor to different application needs ranging from wireless sensors to media center. Yet, these protocols within this family are compatible with each other to allow communication and spectrum-sharing coodination among different types of devices. We envision this family to be based on an OFDMlike multichannel physical layer. The contribution of this paper includes the discovery of an asynchronous split-phase protocol with dynamic priority support. This protocol enables powerful devices to achieve a high throughput and protects low power devices with urgent but only occasional transmissions. It is distributed and data collision-free. Moreover, it can support low delays for real time applications. The performance of the protocols are evaluated using an extension of NS-2. The results demonstrate the coexistence of devices with disparate radio characteristics and the support of applications with different requirements with good performance. I