Information capacity

The repertoire of neural activity patterns that a cortical network can produce constrains the ability of the network to transfer and process information. Here, we measured activity patterns obtained from multisite local field potential recordings in cortex cultures, urethaneanesthetized rats, and awake macaque monkeys. First, we quantified the information capacity of the pattern repertoire of ongoing and stimulus-evoked activity using Shannon entropy. Next, we quantified the efficacy of information transmission between stimulus and response using mutual information. By systematically changing the ratio of excitation/inhibition (E/I) in vitro and in a network model, we discovered that both information capacity and information transmission are maximized at a particular intermediate E/I, at which ongoing activity emerges as neuronal avalanches. Next, we used our in vitro and model results to correctly predict in vivo information capacity and interactions between neuronal groups during ongoing activity. Close agreement between our experiments and model suggest that neuronal avalanches and peak information capacity arise because of criticality and are general properties of cortical networks with balanced E/I.

To date, the dominant approach to leadership research assumes that all aspects of the leadership role within a team are embodied by a single individual. In the real world, however, this is rarely the case. Rather, multiple individuals within the team may serve as leaders in both formal and informal capacities, and the shifting of leadership responsibilities is often rooted in which individual's expertise is most relevant to the given problem. In the present effort, we add to the rapidly growing body of work that focuses on the distribution of the leadership role among multiple individuals. We have reviewed relevant extant literature and proposed an integrated framework for understanding the collective leadership process. Also, in developing this framework we have taken an information and expertise-based approach such that we propose that collective leadership, or the distribution of the leadership role, is a function of selectively utilizing the information or specialized expertise that individuals within the network possess. In reviewing the framework, 55 propositions with regard to the collective leadership process are outlined and suggestions for future research are provided.

Coherent wave propagation in disordered media gives rise to many fascinating phenomena as diverse as universal conductance fluctuations in mesoscopic metals and speckle patterns in light scattering. Here, the theory of electromagnetic wave propagation in diffusive media is combined with information theory to show how interference affects the information transmission rate between antenna arrays. Nontrivial dependencies of the information capacity on the nature of the antenna arrays are found, such as the dimensionality of the arrays and their direction with respect to the local scattering medium. This approach provides a physical picture for understanding the importance of scattering in the transfer of information through wireless communications.

Author contributions: P.H. and M.N.M. contributed equally to this work; P.H., M.N.M., L.M., and S.R. designed research; P.H. and M.N.M. performed research; P.H. and M.N.M. contributed new reagents/analytic tools; P.H., M.N.M., and S.R. analyzed data; and P.H., M.N.M., and S.R. wrote the paper.

In the simplest view of transcriptional regulation, the expression of a gene is turned on or off by changes in the concentration of a transcription factor (TF). We use recent data on noise levels in gene expression to show that it should be possible to transmit much more than just one regulatory bit. Realizing this optimal information capacity would require that the dynamic range of TF concentrations used by the cell, the input/output relation of the regulatory module, and the noise levels of binding and transcription satisfy certain matching relations. This parameter-free prediction is in good agreement with recent experiments on the Bicoid/Hunchback system in the early Drosophila embryo, and this system achieves ∼ 90% of its theoretical maximum information transmission.

It is shown that the capacity scaling of wireless networks is subject to a fundamental limitation which is independent of power attenuation and fading models. It is a degrees of freedom limitation which is due to the laws of physics. By distributing uniformly an order of n users wishing to establish pairwise independent communications at fixed wavelength inside a two-dimensional domain of size of the order of n, there are an order of n communication requests originating from the central half of the domain to its outer half. Physics dictates that the number of independent information channels across these two regions is only of the order of p n, so the per-user information capacity must follow an inverse square-root of n law. This result shows that information-theoretic limits of wireless communication problems can be rigorously obtained without relying on stochastic fading channel models, but studying their physical geometric structure.

We derive optimal time-dependent adjustment rules from Shannon's (1948) Information Theory. In a continuous-time LQ prediction problem with a costly rate of information acquisitionprocessing, the optimal prediction evolves smoothly, but jumps at an optimally chosen frequency, when fresh information accrues. A more volatile and persistent target raises the information rate required to maintain a sampling frequency. This cost-e ect moderates and may even reverse the beneÿt-e ect on the value of information, so optimal inertia is unresponsive to and nonmonotonic in the predictability of the environment. Conventional models with a ÿxed cost per observation imply no such cost-e ect, so inertia rises quickly in the predictability of the environment. ?

We present a multiple-input multiple-output (MIMO) optical link based on coherent optics and its ability to exploit the inherent information capacity of multimode fiber. A coherent implementation differs from previous work in optical MIMO by allowing the system to tolerate smaller modal delay spreads, because of a much larger carrier frequency, and yet maintain the necessary diversity needed for MIMO operation. Furthermore, we demonstrate the use of MIMO adaptive equalization to mitigate intersymbol interference when exceeding the bandwidth-length product of the link. The impact of phase noise is studied with numerical simulation.

Thirty-two children with Developmental Coordination Disorder (DCD) and learning disabilities (LD) and their age-matched controls attending normal primary schools were investigated using kinematic movement analysis of fine-motor performance. Three hypotheses about the nature of the motor deficits observed in children with LD were tested: general slowness hypothesis, limited information capacity hypothesis, and the motor control mode hypothesis. Measures of drawing movements were analyzed under different task conditions using a Fitts' paradigm. In a reciprocal aiming task, the children drew straight-line segments between two targets 2.5 cm apart. Three Target Sizes were used (0.22, 0.44, and 0.88 cm). Children used an electronic pen that left no trace on the writing tablet. To manipulate the degree of openloop movement control, the aiming task was performed under two different control regimes: discrete aiming and cyclic aiming. The kinematic analysis of the writing movements of the 32 children with DCD/LD that took part in the experimental study confirmed that besides learning disabilities they have a motor learning problem as well. Overall, the two groups did not Human Movement Science 22 www.elsevier.com/locate/humov differ in response time, nor did they respond differently according to Fitts' Law. Both groups displayed a conventional trade-off between Target Size and average Movement Time. However, while movement errors for children with DCD/LD were minimal on the discrete task, they made significantly more errors on the cyclic task. This, together with faster endpoint velocities, suggests a reduced ability to use a control strategy that emphasizes the terminal control of accuracy. Taken together, the results suggest that children with DCD/LD rely more on feedback during movement execution and have difficulty switching to a feedforward or openloop strategy.

We study the statistics of optical data transmission in a noisy nonlinear fiber channel with a weak dispersion management and zero average dispersion. Applying analytical expressions for the output probability density functions both for a nonlinear channel and for a linear channel with additive and multiplicative noise we calculate in a closed form a lower bound estimate on the Shannon capacity for an arbitrary signal-to-noise ratio.

The concept of invariance of information capacity is discussed and applied to the resolution of an optical system. Methods of obtaining superresolution in microscopy are discussed, and scanning microscopy has many distinct advantages for such applications.

An outer bound on the rate region of noise-free information networks is given. This outer bound combines properties of entropy with a strong information inequality derived from the structure of the network. This blend of information theoretic and graph theoretic arguments generates many interesting results. For example, the capacity of directed cycles is characterized. Also, a gap between the sparsity of an undirected graph and its capacity is shown. Extending this result, it is shown that multicommodity flow solutions achieve the capacity in an infinite class of undirected graphs, thereby making progress on a conjecture of Li and Li. This result is in sharp contrast to the situation with directed graphs, where a family of graphs are presented in which the gap between the capacity and the rate achievable using multicommodity flows is linear in the size of the graph.

A new approach to digital signatures for imaging, which adapts well to multimedia communications in lossy channels is introduced. Rather than attaching the signature's bit-string as a file-header, it is invisibly etched into the image using a new watermarking algorithm. The watermark is "nonfragile," tolerating small distortions but not malicious tampering aimed at modifying the image's content. In particular, the rank-order relationship in local areas throughout the lowest level of the DWT is exploited to encode the watermark. An edge-based message digest is used. The signature is in the form of binary data and the wavelet decomposition coefficients are modified according to this binary sequence. The signature is also embedded and tested within the SPIHT compression algorithm. The information capacity is studied and the experimental results confirm a logarithm relation between the bit rate and the quantization level, which is similar to the Shannon's capacity theorem. Experiments are performed to examine the signature's transparencey and robustness.

Many problems in evolutionary theory are cast in dyadic terms, such as the polar oppositions of organism and environment. We argue that a triadic conceptual structure offers an alternative perspective under which the information generating role of evolution as a physical process can be analyzed, and propose a new diagrammatic approach. Peirce's natural philosophy was deeply influenced by his reception

Changes in a cell's external or internal conditions are usually reflected in the concentrations of the relevant transcription factors. These proteins in turn modulate the expression levels of the genes under their control and sometimes need to perform non-trivial computations that integrate several inputs and affect multiple genes. At the same time, the activities of the regulated genes would fluctuate even if the inputs were held fixed, as a consequence of the intrinsic noise in the system, and such noise must fundamentally limit the reliability of any genetic computation. Here we use information theory to formalize the notion of information transmission in simple genetic regulatory elements in the presence of physically realistic noise sources. The dependence of this "channel capacity" on noise parameters, cooperativity and cost of making signaling molecules is explored systematically. We find that, at least in principle, capacities higher than one bit should be achievable and that consequently genetic regulation is not limited the use of binary, or "on-off", components.

Paramyxoviruses cotranscriptionally edit their P gene mRNAs by expanding the number of Gs of a conserved A n G n run. Different viruses insert different distributions of guanylates, e.g., Sendai virus inserts a single G, whereas parainfluenza virus type 3 inserts one to six Gs. The sequences conserved at the editing site, as well as the experimental evidence, suggest that the insertions occur by a stuttering process, i.e., by pseudotemplated transcription. The number of times the polymerase "stutters" at the editing site before continuing strictly templated elongation is directed by a cis-acting sequence found upstream of the insertions. We have examined the stuttering process during natural virus infections by constructing recombinant Sendai viruses with mutations in their cis-acting sequences. We found that the template stutter site is precisely determined (C 1052 ) and that a relatively short region (ϳ6 nucleotides) just upstream of the A n G n run can modulate the overall frequency of mRNA editing as well as the distribution of the nucleotide insertions. The positions more proximal to the 5 A n G n run are the most important in this respect. We also provide evidence that the stability of the mRNA/template hybrid plays a determining role in the overall frequency and range of mRNA editing. When the template U run is extended all the way to the stutter site, adenylates rather than guanylates are added at the editing site and their distribution begins to resemble the polyadenylation associated with mRNA 3 end formation by the viral polymerase. Our data suggest how paramyxovirus mRNA editing and polyadenylation are related mechanistically and how editing sites may have evolved from poly(A)-termination sites or vice versa.

In Georgescu-Roegen's classical, though controversial discussion of entropy in relation to economics, the dualism of mechanical and subjective time plays a pivotal role. I argue that this fundamental distinction also inheres modern approaches to maximum entropy. Following Searle, I introduce the ontological dualism of observer independent and observer relative facts, and show that the notion of entropy also manifests this dualism, in the sense of the contextuality of measurements in experimental settings. Extending on the notion of observer relativity, I argue that the MaxEnt principle can be generalized into a framework of analyzing the evolution of (biological, technological etc.) functions under natural selection, if functions are equated with inference devices. Then, observer relativity is function relativity. In hierarchical evolutionary systems, this corresponds to the Maximum Entropy Production Principle, in the sense that functional evolution approximates gradients of maximum dissipation of energy. Against this background, the Georgescu-Roegen dualism of time translates into the dualism of observer independent entropy, which is the object of MEPP, and observer relative entropy, which is the object of MaxEnt. Both are two aspects under which evolution in general and economic evolution in particular can be analyzed.

The information capacity of wireless communication systems can be increased dramatically by employing multiple transmit and receive antennas [Foschini GJ, Gans MJ. On limits of wireless communications in a fading environment when using multiple antennas. An effective approach to increasing data rate over wireless channels is to employ coding techniques appropriate to multiple transmit antennas, that is space-time coding. Space-time codes introduce temporal and spatial correlation into signals transmitted from different antennas, in order to provide diversity at the receiver, and coding gain over an uncoded system. The spatial-temporal structure of these codes can be exploited to further increase the capacity of wireless systems with a relatively simple receiver structure. This paper provides an overview of space-time coding techniques and the associated signal processing framework.

Abstract A detailed analysis has showed that the quantum secret sharing protocol based on the Grover algorithm (Phys Rev A, 2003, 68: 022306) is insecure. A dishonest receiver may obtain the full information without being detected. A quantum secret-sharing protocol is ...

The paper evaluates a previous uni-axial creep testpiece design which has slitted extensometer ridges to relieve the constraint to axial deformation provided by conventional, or unslitted, ridges. The results of experiments are reported on slitted and unslitted ridged testpieees; and they are used together with theoretical studies to evaluate the effectiveness of the slitted ridged testpiece design for different specimen gauge lengths. Firstly, the test results are used to derive true constitutive equations (i.e. those equations for testpieces without ridges), these are then used to predict the response of the majority of the testpieces, using the creep Continuum Damage Mechanics (CDM) Finite Element solver DAMAGE XX. The creep rupture mechanisms, lifetimes and accuracy of the measured creep strains have been determined theoretically for testpieces with unslitted and slitted extensometer ridges and gauge lengths of 50, 30 and 10 ram. Close agreement has been obtained between the experimental and theoretical results for the creep failure mode and lifetimes. It has been shown how the accuracy of the creep behaviour measured using short gauge length testpieces (10 mm), of the type used in tension-compression testing, may be greatly improved by using slitted extensometer ridges.

We outline a theoretical framework to analyze information processing in biological sensory organs and in engineered microsystems. We employ the mathematical tools of communication theory and model natural or synthetic physical structures as microscale communication networks, studying them under physical constraints at two different levels of abstraction. At the functional level, we examine the operational and task specification, while at the physical level, we examine the material specification and realization. Both levels of abstraction are characterized by Shannon's channel capacity, as determined by the channel bandwidth, the signal power, and the noise power. The link between the functional level and the physical level of abstraction is established through models for transformations on the signal, physical constraints on the system, and noise that degrades the signal.

In this paper, we study a coherent optical MIMO (COMIMO) multi-mode fiber link proposed for enhancing the fiber information capacity. We examine the statistical characterization of the equivalent MIMO channel and the improvement in the fiber capacity due to MIMO transmission. It is shown that the equivalent channel behaves similarly to a complex Gaussian MIMO channel, suggesting that the available results on wireless MIMO communication systems can be applied to optical fiber links for capacity enhancement.

Although the relational representation of Entity-Relationship (ER) structures gained extensive coverage, scarce attention has been paid to the issue of correctness for such representations. Several mappings have been proposed for the representation of both ER and extended ER (EER) structures by relational schemas. The informal nature of most of these proposals, however, does not allow a precise evaluation of their correctness, nor a comparison of the various mappings. We propose a canonic4l relational representation for EER structures and prove its correctness. We claim that a relational schema represents correctly an EER structure if it has eqzliwalent information-capacity with the corresponding canonical representation.

In this work, we propose a new type of activation function for a complex valued neural network (CVNN). This activation function is a special Möbius transformation classified as reflection. It is bounded outside of the unit disk and has partial continuous derivatives but not differentiable since it does not satisfy the Cauchy-Riemann equalities. However, the fixed points set of this function is a circle. Therefore, we employ this activation to a specific complex valued Hopfield neural network (CVHNN) and increase the number of fixed points. Using of this activation function leads us also to guarantee the existence of fixed points of the CVHNN. It is shown that the fixed points are all attractive which indicates that storage capacity of the CVHNN is enlarged.

We consider the additivity of the minimal output entropy and the classical information capacity of a class of quantum channels. For this class of channels the norm of the output is maximized for the output being a normalized projection. We prove the additivity of the minimal output Renyi entropies with entropic parameters α ∈ [0, 2], generalizing an argument by Alicki and Fannes, and present a number of examples in detail. In order to relate these results to the classical information capacity, we introduce a weak form of covariance of a channel. We then identify several instances of weakly covariant channels for which we can infer the additivity of the classical information capacity. Both additivity results apply to the case of an arbitrary number of different channels. Finally, we relate the obtained results to instances of bi-partite quantum states for which the entanglement cost can be calculated.

The aim of the present study was to investigate the imaging transfer characteristics and the luminescence efficiency (XLE) of powder scintillator for use in X-ray mammography detectors. emits in the red part of the visible spectrum, having very good spectral compatibility with optical sensors employed in digital imaging systems. Three powder scintillating screens, with coating thicknesses 33.1, 46.4 and 63.1 , were prepared in our laboratory. The imaging performance of these screens was assessed by experimental determination of the modulation transfer function (MTF), the noise transfer function (NTF) and the detective quantum efficiency (DQE) as well as a single index image quality parameter such as the information capacity (IC). A theoretical model, describing radiation and light transfer, was used to fit experimental MTF data. This has allowed the estimation of optical attenuation coefficients of the scintillator. In addition, a previously validated Monte Carlo code, based on the X-ray attenuation properties and on the Mie light scattering theory, was used to estimate the X-ray detection efficiency, the Swank factor and the zero frequency DQE of the scintillator. Results showed that exhibits high MTF and DQE values, which are comparable to those of a commercially employed screen. In addition shows high compatibility (effective gain) to CCDs and to recently introduced CMOS based detectors. Considering our image quality parameters and luminescence efficiency results, this material can potentially be considered for use in digital X-ray mammography detectors.

Inspired by the local minority game, we propose a network Boolean game and investigate its dynamical properties on scale-free networks. The system can self-organize to a stable state with better performance than random choice game, although only the local information is available to the agent. By introducing the heterogeneity of local interactions, we find the system has the best performance when each agent's interaction frequency is linear correlated with its information capacity. Generally, the agents with more information gain more than those with less information, while in the optimal case, each agent almost has the same average profit. In addition, we investigate the role of irrational factor and find an interesting symmetrical behavior.

 In order to investigate the usefulness of unique synthetic DNA tracers in groundwater, a field experiment was conducted in Norway. DNA tracers and a sodium-chloride tracer were injected into an aquifer. The transport of DNA molecules was interpreted by comparing with the plume of chloride ions under forced-gradient steady-state flow conditions. Spatial concentration moments described the migration of conservative tracers. Mobility and migration of DNA in groundwater demonstrate that DNA tracers can be detected by using the polymerase chain reaction (PCR) and DNA sequence analysis. The results indicate that DNA tracers can be valuable tools as tracers in groundwater investigations. Afin d'analyser l'utilisation de traceurs ADN synthétiques uniques pour les eaux souterraines, une expérimentation a été conduite sur le terrain en Norvège. Des traceurs ADN et du chlorure de sodium ont été injectés dans un aquifère. Le transport des molécules d'ADN a été interprété par comparaison avec le panache d'ions chlorure soumis à des conditions d'écoulement en gradient imposé et en régime permanent. Les moments de la concentration spatiale décrivent la migration des traceurs conservatifs. La mobilité et la migration de l'ADN dans l'eau souterraine montrent que les traceurs ADN peuvent être détectés en utilisant une réaction polymérase en chaîne et l'analyse séquentielle de l'ADN. Les résultats indiquent que les traceurs ADN peuvent être des outils intéressants en tant que traceurs pour l'étude des eaux souterraines. Se realizó un experimento en Noruega para investigar la utilidad de un ADN sintético como trazador del agua subterránea en campo. Se inyectaron ADN y NaCl como trazadores bajo condiciones de flujo forzado estacionario, y se comparó el transporte de moléculas de ADN con el penacho de ion cloruro obtenido. La migración de los trazadores se describe mediante los momentos espaciales de la concentración. El ADN como trazador se detecta a partir de la reacción en cadena de polimerasa y la secuencia de análisis del ADN. Los resultados indican que el ADN puede ser un trazador útil para estudios hidrogeológicos.

In order to understand how populations of neurons encode information about external correlates, it is important to develop minimal models of the probability of neural population responses which capture all the salient changes of neural responses with stimuli. In this context, it is particularly useful to determine whether interactions among neurons responding to stimuli can be described by a pairwise interaction model, or whether an higher order interaction model is needed. To address this question, we compared real neural population activity obtained from the rat somatosensory cortex to maximum-entropy models which take into account only interaction of up any given order. By performing these comparisons, we found that interactions of order two were sufficient to explain a large amount of observed stimulus-response distributions, but not all of them. Triple-wise interactions were necessary to fully explain the data. We then used Shannon information to compute the impact of high order correlations on the amount of somatosensory information transmitted by the neural population. We found that correlations of order two gave a good approximation of information carried by the neural population, within 5% of the true value. Third order correlations did even better, providing an almost perfect approximation to the information carried by neural activity. Taken together, these results suggest that higher order interactions exist and shape the dynamics of cortical networks, but play a quantitatively minor role in determining the information capacity of neural populations.

We study the coherent storage and retrieval of a very short multimode light pulse in an atomic ensemble. We consider a quantum memory process based on the conversion of a signal pulse into a long-lived spin coherence via light matter interaction in an on-resonant Λ -type system. In order to study the writing and reading processes we analytically solve the partial differential equations describing the evolution of the field and of the atomic coherence in time as well as in space. We show how to optimize the process for writing as well as for reading. If the medium length is fixed, for each length, there is an optimal value of the pulse duration. We discuss the information capacity of this memory scheme and we estimate the number of transverse modes that can be stored as a quantum hologram.

Shannon's theory of information for communication channels is used to assess the performance of line-scan and sensor-array imaging systems and to optimize the design trade-offs involving sensitivity, spatial response, and sampling intervals. Formulations and computational evaluations account for spatial responses typical of line-scan and sensor-array mechanisms, lens diffraction and transmittance shading, defocus blur, and square and hexagonal sampling lattices.

We propose an order index, , which gives a quantitative measure of randomness and order of complete genomic sequences. It maps genomes to a number from 0 ͑random and of infinite length͒ to 1 ͑fully ordered͒ and applies regardless of sequence length. The 786 complete genomic sequences in GenBank were found to have values in a very narrow range, g = 0.031 −0.015 +0.028

As research instruments with large information capacities become a reality, automated systems for intelligent data analysis become a necessity. Scientific archives containing huge volumes of data preclude manual manipulation or intervention and require automated exploration and mining that can at least pre-classify information in categories. The large dataset from the radio plasma imager (RPI) instrument onboard the IMAGE satellite shows a critical need for such exploration in order to identify and archive features of interest in the volumes of visual information. In this research we have developed such a pre-classifier through a model of preattentive vision capable of detecting and extracting traces of echoes from the RPI plasmagrams. The overall design of our model complies with Marr's paradigm of vision where elements of increasing perceptual strength are built bottom up under the Gestalt constraints of good continuation and smoothness. The specifics of the RPI data, however, demanded extension of this paradigm to achieve greater robustness for signature analysis. Our pre-attentive model now employs a feedback neural network that refines alignment of the oriented edge elements (edgels) detected in the plasmagram image by subjecting them to collective global-scale optimization. The level of interaction between the oriented edgels is determined by their distance and mutual orientation in accordance with the Yen and Finkel model of the striate cortex that encompasses findings in psychophysical studies of human vision. The developed models have been implemented in an operational system "CORPRAL" (Cognitive Online RPI Plasmagram Ranking Algorithm) that currently scans daily submissions of the RPI plasmagrams for the presence of echo traces. Qualifying plasmagrams are tagged in the mission

Conceptual schemata each representing some component of a system in the making, can be integrated in a variety of ways. Herein, we explore some fundamental notions of this. In particular, we examine some ways in which integration using correspondence assertions affects the interrelationship of two component schemata. Our analysis of the logic leads us to reject the commonly asserted requirement of constraining correspondence assertions to single predicates from a source schema. Much previous work has focussed on dominance with regard to preservation of information capacity as a primary integration criterion. However, even though it is desirable that the information capacity of a combined schema dominate one or both of its constituent schemata, we here discuss some aspects of why domination based on information capacity alone is insufficient for the integration to be semantically satisfactory, and we provide a framework for detecting mappings that prevent schema domination.

Summary. Early physiological studies em- phasized changes in the discharge rate of basal ganglia in the pathophysiology of Parkinson's disease (PD), whereas recent studies stressed the role of the abnormal oscil- latory activity and neuronal synchronization of pallidal cells. However, human observa- tions cast doubt on the synchronization hypothesis since increased synchronization may be an epi-phenomenon of the tremor or

Recent renewed interest in the study of rhythmic behaviors and pattern-generating circuits has been inspired by the currently well-established role of oscillating neuronal networks in all aspects of the function of our nervous system: from sensory integration to central processing, and ...

Information-theoretically secure string oblivious transfer (OT) can be constructed based on discrete memoryless channel (DMC). The oblivious transfer capacity of a channel characterizes -similarly to the (standard) information capacity -how efficiently it can be exploited for secure oblivious transfer of strings. The OT capacity of a Generalized Erasure Channel (GEC) -which is a combination of a (general) DMC with the erasure channel -has been established by Ahlswede and Csizar at ISIT'07 in the case of passive adversaries. In this paper, we present the protocol that achieves this capacity against malicious adversaries for GEC with erasure probability at least 1/2. Our construction is based on the protocol of Crépeau and Savvides from Eurocrypt'06 which uses interactive hashing (IH). We solve an open question posed by the above paper, by basing it upon a constant round IH scheme (previously proposed by Ding et al at TCC'04). As a side result, we show that Ding et al IH protocol can deal with transmission errors.

For an involution h : R Ã ! R Ã over a finite alphabet R we consider involution codes: h-infix, h-comma-free, h-k -codes and h-subword-k-codes. These codes arise from questions on DNA strand design. We investigate conditions under which both X and X þ are same type of involution codes. General methods for generating such involution codes are given. The information capacity of these codes show to be optimized in most cases. A specific set of these codes was chosen for experimental testing and the results of these experiments are presented.

A low-cost, portable, video-camera system built by University of Bristol for the UK-DRA, Fort Halsteads, permits in-field acquisition of terrestrial hyper-spectral image sets. Each set is captured as a sequence of thirty-one images through a set of different interference filters which span the visible spectrum, at 10 nm intervals: effectively providing a spectrogram 256x256 pixels. The system is customised from of-the-shelf components. A database of twenty nine hyper-spectral images sets was acquired and analysed as a sample of natural environment. We report the manifest information capacity with respect to spatial and optical frequency drawing implications for management of hyper-spectral data and visual processing.

Capacity for information in biological molecules is traditionally thought to reside in the primary sequence of proteins and RNA, recorded in the DNA. With the exception of some RNA molecules, proteins, if not structural, carry their information in binding sites for substrates of reactions, or in binding sites for control molecules. Some proteins bind to complex carbohydrates in a carbohydrate-specific fashion, including enzymes, lectins and antibodies. These carbohydrates, assembled by sequential glycosyl transferases, also carry biological information, the other side of which is a binding protein that recognizes a specific sugar monosaccharides, sequence, anomerity, linkage, ring size, branching and substitution. It is the latter 7 parameters, however, that give carbohydrates a very large potential for information-carrying capacity in a short sequence. An exponentially growing body of knowledge exists in this aspect of carbohydrate function.

The goal of the paper is a discussion of possibilities, methods and results of application of the optimal signal processing technique to design and optimisation of the cyclic A/D converters (CADC). New effects appearing in CADC computing the codes of the input samples using optimal signal processing algorithms and long-word binary arithmetic, are analysed. There is shown that the intelligent CADC (ICADC) built on this principle most efficiently utilise the resources of their analogue and digital parts, and their performance may achieve theoretically available upper boundaries. Analytical expressions for upper boundaries of sub-optimal ICADC resolution, speed of conversion and information capacity are presented. Principles of ICADC computer analysis and assessment of their performance, as well as the questions of practical implementation of the converters are discussed.

The unprecedented access offered by the World Wide Web brings with it the potential to gather huge amounts of data on human activities. Here we exploit this by using a toy model of financial markets, the Minority Game (MG), to investigate human speculative trading behaviour and information capacity. Hundreds of individuals have played a total of tens of thousands of game turns against computer-controlled agents in the Web-based Interactive Minority Game. The analytical understanding of the MG permits fine-tuning of the market situations encountered, allowing for investigation of human behaviour in a variety of controlled environments. In particular, our results indicate a transition in players' decision-making, as the markets become more difficult, between deductive behaviour making use of short-term trends in the market, and highly repetitive behaviour that ignores entirely the market history, yet outperforms random decision-making.

Information-theoretic capacity notions for a slotted Aloha random-access system are considered in this paper, as well as joint power and retransmission controls for this protocol. The effect of the bursty nature of the arrival and transmission process on the information-carrying capability and spectral efficiency of the system is studied. The nature of the random-access protocol used to resolve decoding failures determines the system stability and dynamics, and in consequence its capacity. System control is carried out by dynamic control of retransmission probability and by power control. It is shown that substantial performance improvements can be achieved under this control scheme in terms of throughput and spectral efficiency for a range of channel parameters. The tradeoffs involving coding rate, system throughput, and spectral efficiency are analyzed from an information-theoretic point of view.

Recent progress in model-robust designs has focused on maximiz-1 ing estimation capacities. However, for a given design, two competing models may be both estimable and yet difficult or impossible to discriminate in the model selection procedure. In this paper, we propose several criteria for gauging the capability of a design for model discrimination. The criteria are then used to evaluate a class of 18-run orthogonal designs in terms of their model-discriminating capabilities.

Precursors of the superior information processing capabilities of our cortex can most probably be traced back to simple invertebrate systems. Using a unique set of newly developed neuronal preparations and state-of-the-art analysis tools, we show that insect neurons have the ability to self-regulate the information capacity of their electrical activity. We characterize the activity of a distinct population of neurons under progressive levels of structural and functional constraints: self-formed networks of neuron clusters in vitro; isolated ex vivo ganglions; in vivo task-free, and in vivo task-forced neuronal activity in the intact animal. We show common motifs and identify trends of increasing self-regulated complexity. This important principle may have played a key role in the gradual transition from simple neuronal motor control to complex information processing. Wiley Periodicals, Inc. Complexity 9: 25-32, 2004

Multiple antenna transmission methods are currently being developed all around the world for evolving 3G wireless standards. Space-Time Trellis Code (STTC) has been proven to use transmit diversity efficiently. It effectively exploits the effects of multipath fading to increase the information capacity of the multiple antenna transmission systems. STTC is a channel coding technique that maximises the 'distance' between different symbol matrices such that the probability of transmission errors are decreased when transmitting redundant symbol or in other words, to maximise the minimum determinant. Maximising the minimum determinant is equivalent to obtaining optimal generator matrix G. Instead of using state diagrams, optimal generator matrix G discussed in this paper is obtained using an improved algorithm which is based on Lisya tree structure. Optimal generator matrix G in this paper has a minimum determinant of 48 which is the highest coding gain obtained so far.

We propose an order index, phi, which quantifies the notion of ``life at the edge of chaos'' when applied to genome sequences. It maps genomes to a number from 0 (random and of infinite length) to 1 (fully ordered) and applies regardless of sequence length. The 786 complete genomic sequences in GenBank were found to have phi values in a very narrow range, 0.037+/-0.027. We show this implies that genomes are halfway towards being completely random, namely, at the edge of chaos. We argue that this narrow range represents the neighborhood of a fixed-point in the space of sequences, and genomes are driven there by the dynamics of a robust, predominantly neutral evolution process.

An on-chip intermodule self-timed communication system is considered in which symbols are encoded by means of phase difference between transitions of signals on parallel wires. The reliability of such a channel is governed and significantly lowered by capacitive crosstalk effects between adjacent wires. A more robust high-speed phase-encoded channel can be designed by minimizing its vulnerability to crosstalk noise. This paper investigates the impact of crosstalk on phase-encoded transmission channels. A functional fault model is presented to characterize the problem. Two fault-tolerant schemes are introduced which are based on information redundancy techniques and a partial-order coding concept. The area overheads, performance, and fault-tolerant capability of those methods are compared. It is shown that a substantial improvement in the performance can be obtained for four-wire channels when using the fault-tolerant design approach, at the expense of 25 percent of information capacity per symbol.