A Spectral Factorization Approach to Pseudo-QMF Design

A new approach to the design of M-channel pseudoquadrature-mirror-filter (QMF) banks is presented. In this approach, the prototype filter is obtained as a spectral factor of a 2Mth band filter. This completely eliminates the need for optimization whereas in conventional pseudo-QMF designs, the main computational effort is in optimization of the prototype. As in the conventional approach, the aliasing cancellation (AC) constraint ensures that all the significant aliasing terms are canceled. The overall transfer function T(z) of the analysis/synthesis system has a linear phase and an approximately “flat” magnitude response in the frequency region ε ≤ ω ≤ (π - ε), where ε depends on the transition bandwidth of the prototype and 0 < ε < (π/2M). Three design examples are included

Invariance of density correlations with charge density in polyelectrolyte solutions

We present a theory for the equilibrium structure of polyelectrolyte solutions. The main element is a simple, new optimization scheme that allows theories such as the random phase approximation (RPA) to handle the harsh repulsive forces present in such systems. Comparison is made with data from recent neutron scattering experiments of randomly charged, hydrophilic polymers in salt-free, semi-dilute solution at various charge densities. Models with varying degrees of realism are examined. The usual explanation of the invariance observed at high charge density has been counterion condensation. However, when polymer-polymer correlations are treated properly, we find that modeling polymer-counterion correlations at the level of Debye-Huckel theory is sufficient.Comment: 4 pages, 2 figure

California Carbon Offsets and Working Forest Conservation Easements

California’s cap-and-trade system is a vital laboratory for testing the effectiveness of this market-driven approach in meeting greenhouse gas emission reduction goals and the use of forestry-based carbon offsets within these systems generally. Based on this experience, this Article explores one of the primary challenges, layering offsets with working forest conservation easements, which currently limits opportunities to effectively use these tools in concert. Ultimately, this market may need to foster and rely on natural linkages with working forest conservation easements to develop these offsets and to better ensure that the critical societal objectives of these projects are being met

Golden Rice: A Case Study in Intellectual Property Management and International Capacity Building

The authors examine the management of risks associated with intellectual property linked to agri-biotech products, with emphasis on the international movement of agri-biotech intellectual property from industrialized to developing nations

Quantum Uncertainty Considerations for Gravitational Lens Interferometry

The measurement of the gravitational lens delay time between light paths has relied, to date, on the source having sufficient variability to allow photometric variations from each path to be compared. However, the delay times of many gravitational lenses cannot be measured because the intrinsic source amplitude variations are too small to be detectable. At the fundamental quantum mechanical level, such photometric time stamps allow which-path knowledge, removing the ability to obtain an interference pattern. However, if the two paths can be made equal (zero time delay) then interference can occur. We describe an interferometric approach to measuring gravitational lens delay times using a quantum-eraser/restorer approach, whereby the time travel along the two paths may be rendered measurably equal. Energy and time being non-commuting observables, constraints on the photon energy in the energy-time uncertainty principle, via adjustments of the width of the radio bandpass, dictate the uncertainty of the time delay and therefore whether the path taken along one or the other gravitational lens geodesic is knowable. If one starts with interference, for example, which-path information returns when the bandpass is broadened (constraints on the energy are relaxed) to the point where the uncertainty principle allows a knowledge of the arrival time to better than the gravitational lens delay time itself, at which point the interference will disappear. We discuss the near-term feasibility of such measurements in light of current narrow-band radio detectors and known short time-delay gravitational lenses.Comment: 22 page

Golden Rice: A Case Study in Intellectual Property Management and International Capacity Building

In order for agricultural biotechnology (agri-biotech) to play a larger role in the development of sustainable agricultural systems, intellectual property (IP) rights management must be addressed. These issues are not limited to developing countries. With increased globalization, the management of agri-biotech IP rights affects both developing and industrialized countries. In industrialized countries, for example, IP rights risk management entails protection of inventions via strong patent portfolios. For developing countries, IP rights risk management includes the acquisition of rights requisite for the use of inventions essential to the basic welfare of the population. Strategies are needed to bridge these disparate IP management paradigms to facilitate the successful transfer of the agri-biotech from an industrialized country source to a developing country recipient. This paper examines IP management linked to agri-biotech products. Further, this paper examines Golden Rice, a genetically engineered rice strain that accumulates beta-carotene (i.e., pro-vitamin A) in the endosperm tissue of grain, as a case study for IP management, with emphasis on the international movement of agri-biotech from industrialized to developing countries. Topics discussed include: the application of agri-biotech to international development; the challenge of transferring this technology from industrialized to developing countries; a method for evaluating the IP constraints impinging on the deployment of Golden Rice; industrialized/developing country perspectives vis-a-vis IP rights management; six shorter-term options for the management of IP connected to Golden Rice; and a longer-term proposed path to sustainable transfers of agri-biotech products