The rate distortion region for the multiple description problem

We derive the rate-distortion region for the two-channel multiple description problem on stationary discrete ergodic and nonergodic sources with alphabets admitting an ergodic decomposition. The results do not provide a single-letter representation for the rate-distortion region on i.i.d. sources

Rate-distortion with mixed types of side information

We present the rate-distortion function and bound the rate loss for a system with some side information (s.i.) known at both the encoder and decoder, and some known only at the decoder. We extend the corresponding Wyner-Ziv rate-distortion results to give a lower bound for jointly Gaussian sources and upper and lower bounds for binary symmetric sources. Applying the construction from our binary upper bound to the Heegard and Berger (HB) problem of decoding when s.i. may be present improves the best upper bound for that problem. Applying it to the two-receiver system with different s.i. at each decoder provides a new upper bound

On rate-distortion with mixed types of side information

In this correspondence, we consider rate-distortion examples in the presence of side information. For a system with some side information known at both the encoder and decoder, and some known only at the decoder, we evaluate the rate distortion function for both Gaussian and binary sources. While the Gaussian example is a straightforward generalization of the corresponding result by Wyner, the binary example proves more difficult and is solved using a multidimensional optimization approach. Leveraging the insights gained from the binary example, we then solve the more complicated binary Heegard and Berger problem of decoding when side information may be present. The results demonstrate the existence of a new type of successive refinement in which the refinement information is decoded together with side information that is not available for the initial description

Measuring treasury market liquidity

This paper was presented at the conference "Economic Statistics: New Needs for the Twenty-First Century," cosponsored by the Federal Reserve Bank of New York, the Conference on Research in Income and Wealth, and the National Association for Business Economics, July 11, 2002. Securities liquidity is important to those who transact in markets, those who monitor market conditions, and those who analyze market developments. This article estimates and evaluates a comprehensive set of liquidity measures for the U.S. Treasury securities market. The author finds that the commonly used bid-ask spread-the difference between bid and offer prices-is a useful measure for assessing and tracking liquidity. The spread is highly correlated with a more sophisticated price impact measure and is correlated with episodes of reported poor liquidity in the expected manner. He also finds that other measures correlate less strongly with episodes of poor liquidity and with the bid-ask spread and price impact measures, indicating that they are only modest proxies for market liquidity. Trading volume and trading frequency, in particular, are found to be weak proxies for market liquidity, as both high and low levels of trading activity are associated with periods of poor liquidity.Liquidity (Economics) ; Treasury bills ; Treasury notes ; Government securities

Who buys Treasury securities at auction?

The U.S. Treasury Department now releases fuller information about its auctions than in the past, including new information on investor class and bidder category. The investor class data shed light on the distribution of demand for government securities, and the bidder category data, released first, offer an early read on demand. Purchases by indirect bidders, in particular, are a fairly good proxy for foreign purchases of Treasury notes, but not Treasury bills.Auctions ; Treasury notes ; Treasury bills ; Government securities

The benchmark U.S. Treasury market: recent performance and possible alternatives

Forecasting ; Economic indicators ; Treasury bills ; Government securities ; Budget ; Debts, Public

Gravitational Coset Models

The algebra A(D-3)+++ dimensionally reduces to the E(D-1) symmetry algebra of (12-D)-dimensional supergravity. An infinite set of five-dimensional gravitational objects trivially embedded in D-dimensions is constructed by identifying the null geodesic motion on cosets embedded in the generalised Kac-Moody algebra A(D-3)+++. By analogy with supergravity these are bound states of dual gravitons. The metric interpolates continuously between exotic gravitational solutions generated by the action of the Geroch group but is not a continuously transforming solution of the Einstein-Hilbert action. We investigate mixed-symmetry fields in the brane sigma model, identify actions for the full interpolating bound state and understand the obstruction to the bound state being a solution of the Einstein-Hilbert action.Comment: 46 page

Integrated financial supervision : lessons of Northern European experience

Drawing on Northern European experience - where three Scandinavian countries have practiced integrated supervision for the past 10 years - the authors address three policy-related issues associated with the integrated model: a) Under what conditions should (or should not) a country consider moving toward an integrated model of financial supervision? Clearly, for a small transition or developing economy, or an economy with a small financial sector, the economies of scale from establishing an integrated agency outweigh the costs of moving to such a model. A strong case can also be made for an integrated approach in a financial sector dominated by banks, with little role for capital markets or a highly integrated financial sector. b) How should an integrated agency be structured, organized, and managed? There is no single obviously correct organizational structure, and existing agencies are experimenting with a variety of forms. An institutionally based structure has the virtue of simplicity and can be implemented fairly quickly, but tends to preserve the cultures and identities of the predecessor agencies more than is optimal. Whatever the structure, integrated supervision requires active management to secure the potential benefits that the approach offers. C) How should the integration process be implemented? While the decision to move to an integrated agency must be carefully thought through in the context of the country concerned, the more difficult part is implementation, which must be sensitively managed. Once the decision has been made, implementation should take place as quickly as possible. A well-conceived"change management"process should aim to overcome the cultural barriers associated with the previous fragmented structure. The authors'review of Northern European experience with integration of financial supervision raises a range of questions relevant to developing and transition economies, which they discuss.Financial Intermediation,Banks&Banking Reform,Insurance&Risk Mitigation,Environmental Economics&Policies,National Governance

Network vector quantization

We present an algorithm for designing locally optimal vector quantizers for general networks. We discuss the algorithm's implementation and compare the performance of the resulting "network vector quantizers" to traditional vector quantizers (VQs) and to rate-distortion (R-D) bounds where available. While some special cases of network codes (e.g., multiresolution (MR) and multiple description (MD) codes) have been studied in the literature, we here present a unifying approach that both includes these existing solutions as special cases and provides solutions to previously unsolved examples