Search results for " Coding"
showing 10 items of 139 documents
Prior Precision Modulates the Minimization of Auditory Prediction Error
2019
International audience; The predictive coding model of perception proposes that successful representation of the perceptual world depends upon canceling out the discrepancy between prediction and sensory input (i.e., prediction error). Recent studies further suggest a distinction to be made between prediction error triggered by non-predicted stimuli of different prior precision (i.e., inverse variance). However, it is not fully understood how prediction error with different precision levels is minimized in the predictive process. Here, we conducted a magnetoencephalography (MEG) experiment which orthogonally manipulated prime-probe relation (for contextual precision) and stimulus repetition…
The Myriad Virtues of Wavelet Trees
2009
Wavelet Trees have been introduced in [Grossi, Gupta and Vitter, SODA '03] and have been rapidly recognized as a very flexible tool for the design of compressed full-text indexes and data compressors. Although several papers have investigated the beauty and usefulness of this data structure in the full-text indexing scenario, its impact on data compression has not been fully explored. In this paper we provide a complete theoretical analysis of a wide class of compression algorithms based on Wavelet Trees. We also show how to improve their asymptotic performance by introducing a novel framework, called Generalized Wavelet Trees, that aims for the best combination of binary compressors (like,…
Textual data compression in computational biology: Algorithmic techniques
2012
Abstract In a recent review [R. Giancarlo, D. Scaturro, F. Utro, Textual data compression in computational biology: a synopsis, Bioinformatics 25 (2009) 1575–1586] the first systematic organization and presentation of the impact of textual data compression for the analysis of biological data has been given. Its main focus was on a systematic presentation of the key areas of bioinformatics and computational biology where compression has been used together with a technical presentation of how well-known notions from information theory have been adapted to successfully work on biological data. Rather surprisingly, the use of data compression is pervasive in computational biology. Starting from…
Novel Iris Biometric Watermarking Based on Singular Value Decomposition and Discrete Cosine Transform
2014
Published version of an article in the journal: Mathematical Problems in Engineering. Also available from the publisher at: http://dx.doi.org/10.1155/2014/926170 A novel iris biometric watermarking scheme is proposed focusing on iris recognition instead of the traditional watermark for increasing the security of the digital products. The preprocess of iris image is to be done firstly, which generates the iris biometric template from person's eye images. And then the templates are to be on discrete cosine transform; the value of the discrete cosine is encoded to BCH error control coding. The host image is divided into four areas equally correspondingly. The BCH codes are embedded in the sing…
The Influence of Spatial Correlation and Severity of Fading on the Statistical Properties of the Capacity of OSTBC Nakagami-m MIMO Channels
2009
This paper deals with the analysis of statistical prop- erties of the capacity of spatially uncorrelated orthogonal space- time block coded (OSTBC) Nakagami-m multiple-input multiple- output (MIMO) channels. We have derived exact closed-form expressions for the probability density function (PDF), cumula- tive distribution function (CDF), level-crossing rate (LCR), and average duration of fades (ADF) of the channel capacity. We have also investigated the statistical properties of the approximated capacity of spatially correlated OSTBC Nakagami-m MIMO channels. The results are studied for different values of the fading parameter m, corresponding to different fading conditions. It is observed …
A Basis Set of Elementary Operations Captures Recombination of Neocortical Cell Assemblies During Basal Conditions and Learning
2019
Cell assemblies — subgroups within neuronal networks — are believed to serve as functional entities underlying cognitive capabilities such as categorical perception or memory formation and storage. However, little is known about their long-term dynamics. Using chronic in vivo calcium imaging in the mouse auditory cortex, we find that cell assemblies undergo continuous recombination, even under behaviorally stable conditions. We identify a basis set of elementary operations capturing the dynamics of cell assemblies, which involve plasticity of both the stimulus tuning of particular assemblies as well as the cellular composition of an assembly. Auditory fear conditioning introduces biases in …
Channel capacity of fading channels for differentially encoded transmission
1999
The capacity of flat fading channels when applying differential encoding with noncoherent reception and no channel state information available at the receiver is considered. Numerical results indicate the gains achievable by multiple symbol detection in the case of slowly time-varying channels and provide a comparison between schemes with different potential bandwidth efficiencies.
Analog joint source-channel Multiple Description coding scheme over AWGN parallel channels
2011
We propose a low complexity analog joint source channel coding Multiple Description (MD) scheme for transmitting the symbols of a Gaussian source across a pair of independent AWGN channels. The outputs of these channels have each a separated receiver, whereas a third receiver has both outputs available. At the transmitter side, a pair of bandwidth-reduction analog mappings are used for joint source-channel coding. The presented scheme has the inherent advantage over digital MD schemes based on separation, that coding and decoding can be performed by using a single-letter (or symbol), a strategy that is very suitable for applications where latency originated by the digital compression and th…
Toll-quality digital secraphone
2002
This paper describes the design and performance of a secraphone that, when plugged between any conventional telephone set and the public telephone network, protects the speech information travelling through the PSTN. The device has a transparent operating mode that does not alter the signal and a secure mode, accessed upon request of any of the speakers, that encrypts the speech with digital techniques, assuring privacy against unwanted listeners. At the transmission branch, voice is sampled, coded with a CELP scheme at 9600 bps (with a slow mode at 7200 bps), encrypted with a proprietary algorithm and interfaced to the line with a V.32 modem chip set. The keys for encryption are establishe…
Do Grading Gray Stimuli Help to Encode Letter Position?
2021
Numerous experiments in the past decades recurrently showed that a transposed-letter pseudoword (e.g., JUGDE) is much more wordlike than a replacement-letter control (e.g., JUPTE). Critically, there is an ongoing debate as to whether this effect arises at a perceptual level (e.g., perceptual uncertainty at assigning letter position of an array of visual objects) or at an abstract language-specific level (e.g., via a level of “open bigrams” between the letter and word levels). Here, we designed an experiment to test the limits of perceptual accounts of letter position coding. The stimuli in a lexical decision task were presented either with a homogeneous letter intensity or with a graded gra…