Decay of weak turbulence

Weak turbulence fields generated by single and multiple stage grids covering Reynolds numbers between 7 and 70 showing decay of energy spectr

A charging model for three-axis stabilized spacecraft

A charging model was developed for geosynchronous, three-axis stabilized spacecraft when under the influence of a geomagnetic substorm. The differential charging potentials between the thermally coated or blanketed outer surfaces and metallic structure of a spacecraft were determined when the spacecraft was immersed in a dense plasma cloud of energetic particles. The spacecraft-to-environment interaction was determined by representing the charged particle environment by equivalent current source forcing functions and by representing the spacecraft by its electrically equivalent circuit with respect to the plasma charging phenomenon. The charging model included a sun/earth/spacecraft orbit model that simulated the sum illumination conditions of the spacecraft outer surfaces throughout the orbital flight on a diurnal as well as a seasonal basis. Transient and steady-state numerical results for a three-axis stabilized spacecraft are presented

Discrete gravity and and its continuum limit

Recently Gambini and Pullin proposed a new consistent discrete approach to quantum gravity and applied it to cosmological models. One remarkable result of this approach is that the cosmological singularity can be avoided in a general fashion. However, whether the continuum limit of such discretized theories exists is model dependent. In the case of massless scalar field coupled to gravity with $\Lambda=0$, the continuum limit can only be achieved by fine tuning the recurrence constant. We regard this failure as the implication that cosmological constant should vary with time. For this reason we replace the massless scalar field by Chaplygin gas which may contribute an effective cosmological constant term with the evolution of the universe. It turns out that the continuum limit can be reached in this case indeed.Comment: 16 pages,revised version published in MPL

Cointegration and Price Discovery between Equity and Mortgage REITs

This study analyzes the relationship between equity and mortgage real estate investment trust (REIT) stock prices by performing cointegration tests and causality tests, and estimating an error correction model. Evidence is found that a stable long-run linear relationship exists based on their common reactions to changes in market returns, interest rates and other additional factors. Geweke causality test results indicate a causal relationship running from EREIT stock prices to MREIT stock prices. This may reflect the quicker response of equity REIT stock prices to changes including real estate returns. In addition, the results suggest overall linear dependence (total linear causality) and instantaneous linear feedback between changes in EREIT and MREIT stock prices. The results of the error correction model not only indicate a significant increase in the explanatory power of the model compared with the vector autoregression model but also reveals how the price discovery processes in REIT security markets maintain long-run equilibrium.

Effects of alcohol on subjective ratings of prospective and everyday memory deficits

Background: Research has shown that heavy alcohol use has a detrimental effect on retrospective memory. Less is known about the effect of alcohol on everyday memory. Methods: This study examined self-ratings of two aspects of memory performance: prospective memory (for example, forgetting to pass on a message) and everyday memory (measured by cognitive failures, such as telling someone a joke that you have told them before). To ensure anonymity and expand on the numbers of participants used in previous studies, data were collected by using the Internet. Data from 763 participants remained after data screening. Results: After controlling for other drug and strategy use, there was clear evidence that differential use of alcohol was associated with impairments in the long-term aspect of prospective memory and with an increased number of cognitive failures. Conclusions: These results support and extend the findings of previous research: our findings are consistent with the idea that heavy use of alcohol does have a significant and negative effect on everyday cognitive performance. Possible causes of these impairments are discussed

Weak UCP and perturbed monopole equations

We give a simple proof of weak Unique Continuation Property for perturbed Dirac operators, using the Carleman inequality. We apply the result to a class of perturbations of the Seiberg-Witten monopole equations that arise in Floer theory.Comment: 22 pages LaTeX, one .eps figur

Berry's phase for coherent states of Landau levels

The Berry phases for coherent states and squeezed coherent states of Landau levels are calculated. Coherent states of Landau levels are interpreted as a result of a magnetic flux moved adiabatically from infinity to a finite place on the plane. The Abelian Berry phase for coherent states of Landau levels is an analog of the Aharonov- Bohm effect. Moreover, the non-Abelian Berry phase is calculated for the adiabatic evolution of the magnetic field B.Comment: 4 pages, 1 figur

Anomalous Light Scattering by Topological PT{\mathcal{PT}}-symmetric Particle Arrays

Robust topological edge modes may evolve into complex-frequency modes when a physical system becomes non-Hermitian. We show that, while having negligible forward optical extinction cross section, a conjugate pair of such complex topological edge modes in a non-Hermitian $\mathcal{PT}$-symmetric system can give rise to an anomalous sideway scattering when they are simultaneously excited by a plane wave. We propose a realization of such scattering state in a linear array of subwavelength resonators coated with gain media. The prediction is based on an analytical two-band model and verified by rigorous numerical simulation using multiple-multipole scattering theory. The result suggests an extreme situation where leakage of classical information is unnoticeable to the transmitter and the receiver when such a $\mathcal{PT}$-symmetric unit is inserted into the communication channel.Comment: 16 pages, 8 figure