Multiple-Description Coding by Dithered Delta-Sigma Quantization

We address the connection between the multiple-description (MD) problem and Delta-Sigma quantization. The inherent redundancy due to oversampling in Delta-Sigma quantization, and the simple linear-additive noise model resulting from dithered lattice quantization, allow us to construct a symmetric and time-invariant MD coding scheme. We show that the use of a noise shaping filter makes it possible to trade off central distortion for side distortion. Asymptotically as the dimension of the lattice vector quantizer and order of the noise shaping filter approach infinity, the entropy rate of the dithered Delta-Sigma quantization scheme approaches the symmetric two-channel MD rate-distortion function for a memoryless Gaussian source and MSE fidelity criterion, at any side-to-central distortion ratio and any resolution. In the optimal scheme, the infinite-order noise shaping filter must be minimum phase and have a piece-wise flat power spectrum with a single jump discontinuity. An important advantage of the proposed design is that it is symmetric in rate and distortion by construction, so the coding rates of the descriptions are identical and there is therefore no need for source splitting.Comment: Revised, restructured, significantly shortened and minor typos has been fixed. Accepted for publication in the IEEE Transactions on Information Theor

Colored-Gaussian Multiple Descriptions: Spectral and Time-Domain Forms

It is well known that Shannon's rate-distortion function (RDF) in the colored quadratic Gaussian (QG) case can be parametrized via a single Lagrangian variable (the "water level" in the reverse water filling solution). In this work, we show that the symmetric colored QG multiple-description (MD) RDF in the case of two descriptions can be parametrized in the spectral domain via two Lagrangian variables, which control the trade-off between the side distortion, the central distortion, and the coding rate. This spectral-domain analysis is complemented by a time-domain scheme-design approach: we show that the symmetric colored QG MD RDF can be achieved by combining ideas of delta-sigma modulation and differential pulse-code modulation. Specifically, two source prediction loops, one for each description, are embedded within a common noise shaping loop, whose parameters are explicitly found from the spectral-domain characterization.Comment: Accepted for publications in the IEEE Transactions on Information Theory. Title have been shortened, abstract clarified, and paper significantly restructure

Incremental Refinements and Multiple Descriptions with Feedback

It is well known that independent (separate) encoding of K correlated sources may incur some rate loss compared to joint encoding, even if the decoding is done jointly. This loss is particularly evident in the multiple descriptions problem, where the sources are repetitions of the same source, but each description must be individually good. We observe that under mild conditions about the source and distortion measure, the rate ratio Rindependent(K)/Rjoint goes to one in the limit of small rate/high distortion. Moreover, we consider the excess rate with respect to the rate-distortion function, Rindependent(K, M) - R(D), in M rounds of K independent encodings with a final distortion level D. We provide two examples - a Gaussian source with mean-squared error and an exponential source with one-sided error - for which the excess rate vanishes in the limit as the number of rounds M goes to infinity, for any fixed D and K. This result has an interesting interpretation for a multi-round variant of the multiple descriptions problem, where after each round the encoder gets a (block) feedback regarding which of the descriptions arrived: In the limit as the number of rounds M goes to infinity (i.e., many incremental rounds), the total rate of received descriptions approaches the rate-distortion function. We provide theoretical and experimental evidence showing that this phenomenon is in fact more general than in the two examples above.Comment: 62 pages. Accepted in the IEEE Transactions on Information Theor

An Orthogonality Principle for Select-Maximum Estimation of Exponential Variables

It was recently proposed to encode the one-sided exponential source X via K parallel channels, Y1, ..., YK , such that the error signals X - Yi, i = 1,...,K, are one-sided exponential and mutually independent given X. Moreover, it was shown that the optimal estimator \hat{Y} of the source X with respect to the one-sided error criterion, is simply given by the maximum of the outputs, i.e., \hat{Y} = max{Y1,..., YK}. In this paper, we show that the distribution of the resulting estimation error X - \hat{Y} , is equivalent to that of the optimum noise in the backward test-channel of the one-sided exponential source, i.e., it is one-sided exponentially distributed and statistically independent of the joint output Y1,...,YK.Comment: 5 pages. Submitted to ISI

Sampling versus Random Binning for Multiple Descriptions of a Bandlimited Source

Random binning is an efficient, yet complex, coding technique for the symmetric L-description source coding problem. We propose an alternative approach, that uses the quantized samples of a bandlimited source as "descriptions". By the Nyquist condition, the source can be reconstructed if enough samples are received. We examine a coding scheme that combines sampling and noise-shaped quantization for a scenario in which only K < L descriptions or all L descriptions are received. Some of the received K-sets of descriptions correspond to uniform sampling while others to non-uniform sampling. This scheme achieves the optimum rate-distortion performance for uniform-sampling K-sets, but suffers noise amplification for nonuniform-sampling K-sets. We then show that by increasing the sampling rate and adding a random-binning stage, the optimal operation point is achieved for any K-set.Comment: Presented at the ITW'13. 5 pages, two-column mode, 3 figure

Where People Live and Die Makes a Difference: Individual and Geographic Disparities in Well-Being Progression at the End of Life

Lifespan psychological research has long been interested in the contextual embeddedness of individual development. To examine if and how regional factors relate to between-person disparities in the progression of late-life well-being, we applied three-level growth curve models to 24-year longitudinal data from deceased participants of the German Socio-Economic Panel Study (N = 3,427; age at death: 18 to 101 years). Results indicate steep declines in well-being with impending death, with some 8% of the between-person differences in both level and decline of well-being reflecting between-county differences. Exploratory analyses revealed that individuals living and dying in less affluent counties reported lower late-life well-being, controlling for key individual predictors including age at death, gender, education, and household income. The regional factors examined did not directly relate to well-being change, but were found to moderate (e.g., amplify) the disparities in change attributed to individual factors. Our results suggest that resource-poor counties provide relatively less fertile grounds for successful aging until the end of life and may serve to exacerbate disparities. We conclude that examinations of how individual and residential characteristics interact can further our understanding of individual psychological outcomes and suggest routes for future inquiry.Neighborhoods, Selective mortality, successful aging, differential aging, psychosocial factors, well-being, longitudinal methods

Field Trials of Rapid-Setting Repair Materials

The primary objective of the present study was to identify the critical properties (based on the laboratory tests) that could be correlated to the field performance of the rapid setting repair materials. The first phase of the project involved laboratory evaluation of six commercial rapid-setting repair materials (RMs). When tested in the laboratory, all but two exhibited acceptable rates of strength gain and three RMs displayed relatively poor freeze-thaw resistance. All the RMs exhibited acceptable values for free-shrinkage, high resistance to cracking and good bond to substrate concrete. The resistance to chloride ion penetration of one of the RMs was very poor. The second phase of the project involved field installation and performance evaluation of the RMs. It was seen that while, in most cases, the controlled laboratory conditions yielded consistent mixes and acceptable performance, the properties of mixes produced on site were more variable. This variability was the result of somewhat uncontrolled changes in the amount of aggregate extension used, moisture content of the aggregates, amount water added and ambient temperature conditions. Follow-up inspection of the repair patches indicated that all the patches except one underwent premature failures (primarily cracking and edge de-bonding). The ambient temperature during the repairs was around 10°C and this led to an extended set-time for all the materials. The 12-hr compressive strengths values of the specimens from the field-mixes were in some cases lower than the 4-hr compressive strength values of laboratory mixes. Since the repairs were open to traffic after approximately 4 hours after placement, the low early age strengths could be a potential reason for premature failures of some of the patches. In general, several materials were found to be very sensitive to excess water added during mixing resulted in a significant impact on the durability properties – especially the freeze-thaw resistance. In the field, for most of the materials, the consistency of the mixes varied from batch to batch – this can be attributed to the variations in the aggregate extension adopted, mix-water added and also the moisture content of the aggregates used. Construction related issues (consolidation and finishing) also played an important role in the performance of the repair patches. Based upon laboratory and field results, modifications to the current INDOT performance specifications for rapid-setting repair materials have been suggested. Some recommendations for improvements in quality control measures of field-mixes and construction related issues have been suggested. Future research directions involving the evaluation of the robustness of the repair materials with respect to the uncertainties present on site have also been highlighted

Immunogenicity of HLA Class i and II double restricted influenza a-derived peptides

The aim of the present study was to identify influenza A-derived peptides which bind to both HLA class I and-II molecules and by immunization lead to both HLA class I and class II restricted immune responses. Eight influenza A-derived 9-11mer peptides with simultaneous binding to both HLA-A02:01 and HLA-DRB101:01 molecules were identified by bioinformatics and biochemical technology. Immunization of transgenic HLA-A02:01/HLADRB101:01 mice with four of these double binding peptides gave rise to both HLA class I and class II restricted responses by CD8 and CD4 T cells, respectively, whereas four of the double binding peptides did result in HLA-A02:01 restricted responses only. According to their cytokine profile, the CD4 T cell responses were of the Th2 type. In influenza infected mice, we were unable to detect natural processing in vivo of the double restricted peptides and in line with this, peptide vaccination did not decrease virus titres in the lungs of intranasally influenza challenged mice. Our data show that HLA class I and class II double binding peptides can be identified by bioinformatics and biochemical technology. By immunization, double binding peptides can give rise to both HLA class I and class I restricted responses, a quality which might be of potential interest for peptide-based vaccine development.Fil: Pedersen, Sara Ram. Universidad de Copenhagen; DinamarcaFil: Christensen, Jan Pravsgaard. Universidad de Copenhagen; DinamarcaFil: Buus, Søren. Universidad de Copenhagen; DinamarcaFil: Rasmussen, Michael. Universidad de Copenhagen; DinamarcaFil: Korsholm, Karen Smith. Statens Serum Institute; DinamarcaFil: Nielsen, Morten. Technical University of Denmark; Dinamarca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; ArgentinaFil: Claesson, Mogens Helweg. Universidad de Copenhagen; Dinamarc