Information Transmission Capacity Research Articles

Experimental achievement of the entanglement-assisted capacity for the depolarizing channel

We experimentally demonstrate the achievement of the entanglement-assisted capacity for classical information transmission over a depolarizing channel. The implementation is based on the generation and local manipulation of two-qubit Bell states, which are finally measured at the receiver by realizing projective measurements in the Bell basis. The depolarizing channel is realized by introducing quantum noise in a controlled way on one of the two qubits. This work represents an investigation into the amount of information that can be shared in the presence of noise.

Olfactory Cues Are Subordinate to Visual Stimuli in a Neotropical Generalist Weevil

The tropical root weevil Diaprepes abbreviatus is a major pest of multiple crops in the Caribbean Islands and has become a serious constraint to citrus production in the United States. Recent work has identified host and conspecific volatiles that mediate host- and mate-finding by D. abbreviatus. The interaction of light, color, and odors has not been studied in this species. The responses of male and female D. abbreviatus to narrow bandwidths of visible light emitted by LEDs offered alone and in combination with olfactory stimuli were studied in a specially-designed multiple choice arena combined with a locomotion compensator. Weevils were more attracted to wavelengths close to green and yellow compared with blue or ultraviolet, but preferred red and darkness over green. Additionally, dim green light was preferred over brighter green. Adult weevils were also attracted to the odor of its citrus host + conspecifics. However, the attractiveness of citrus + conspecific odors disappeared in the presence of a green light. Photic stimulation induced males but not females to increase their speed. In the presence of light emitted by LEDs, turning speed decreased and path straightness increased, indicating that weevils tended to walk less tortuously. Diaprepes abbreviatus showed a hierarchy between chemo- and photo-taxis in the series of experiments presented herein, where the presence of the green light abolished upwind anemotaxis elicited by the pheromone + host plant odor. Insight into the strong responses to visual stimuli of chemically stimulated insects may be provided when the amount of information supplied by vision and olfaction is compared, as the information transmission capacity of compound eyes is estimated to be several orders of magnitude higher compared with the olfactory system. Subordination of olfactory responses by photic stimuli should be considered in the design of strategies aimed at management of such insects.

Engineered cell-cell communication via DNA messaging.

BackgroundEvolution has selected for organisms that benefit from genetically encoded cell-cell communication. Engineers have begun to repurpose elements of natural communication systems to realize programmed pattern formation and coordinate other population-level behaviors. However, existing engineered systems rely on system-specific small molecules to send molecular messages among cells. Thus, the information transmission capacity of current engineered biological communication systems is physically limited by specific biomolecules that are capable of sending only a single message, typically “regulate transcription.”ResultsWe have engineered a cell-cell communication platform using bacteriophage M13 gene products to autonomously package and deliver heterologous DNA messages of varying lengths and encoded functions. We demonstrate the decoupling of messages from a common communication channel via the autonomous transmission of various arbitrary genetic messages. Further, we increase the range of engineered DNA messaging across semisolid media by linking message transmission or receipt to active cellular chemotaxis.ConclusionsWe demonstrate decoupling of a communication channel from message transmission within engineered biological systems via the autonomous targeted transduction of user-specified heterologous DNA messages. We also demonstrate that bacteriophage M13 particle production and message transduction occurs among chemotactic bacteria. We use chemotaxis to improve the range of DNA messaging, increasing both transmission distance and communication bit rates relative to existing small molecule-based communication systems. We postulate that integration of different engineered cell-cell communication platforms will allow for more complex spatial programming of dynamic cellular consortia.

Small-worldness of functional networks in Alzheimer's disease

To construct the functional networks of human brains by resting-state functional magnetic resonance imaging (fMRI) and examine whether or not the small-world property of functional brain networks changes in patients with Alzheimer disease (AD). A total of 33 AD patients and 20 healthy old volunteers were recruited. Their cognitive functions were evaluated by the mini-mental state examination (MMSE) and Mattis dementia rating scale (DRS). The resting-state BOLD-fMRI data were acquired and preprocessed. Then the correlation coefficient of every pair of 90 regions was calculated and correlation matrix Z (N×N, N = 90) generated by Fisher Z transformation. The small-world property of functional brain networks was tested for AD patients and normal elders according to the definition of small-worldness. The changes of relevant parameters in AD patients were examined by two sample t-tests. Behavioral results: the MMSE scores of AD group and normal controls (NOR) were 20.60 ± 2.30 and 28.20 ± 1.80 respectively. The DRS scores of AD and NOR groups were 96.00 ± 10.82 and 123.22 ± 13.74 respectively. The MMSE and DRS scores were statistically different between two groups. Calculation of small-world parameters: Within the range of 0.1 ≤ Sparsity ≤ 0.4, both groups satisfied the small-world property. However, the clustering coefficient Cp and the average shortest path Lp of AD group were significantly higher than those of NOR group at each threshold (P < 0.05). The functional brain networks in AD patients still have the property of small-world. But the levels of Cp and Lp are higher in AD patients than those in normal controls. It suggests that the capacity of information transmission in functional brain networks and the ability of information integration in different brain regions in AD patients are impaired. This finding is of great importance in elucidating the pathological mechanisms of AD from the viewpoint of networks.

G.A. Cohen on the Feasibility of Socialism

G.A. Cohen attempts to provide a case for socialism that takes into consideration the reasons why socialism is desirable and some of the problems for its feasibility. He finds that the kind of community sentiment that socialism requires is possible, but the devices of social organization that can facilitate the growth of socialist sentiment along with the effective transmission of information are not currently known. In short, Cohen thinks social scientists and philosophers need to find out how to harness the information transmission capacity of market exchange without the motivational encouragement of rapacious self-interest that market exchange fosters. This paper argues that Cohen's appraisal of the ineffectiveness of informational transmission in socialist planned economies in incorrect. A democratically planned socialist economy can serve as the basis for the fostering of the socialist community sentiment that Cohen advocates along with the required transmission of economic information.

Information processing in the Drosophila Olfactory System: From Odors to Kenyon cells

Information processing in the Drosophila Olfactory System: From Odors to Kenyon cells

Design and Evaluation of Identifiable Key-Click Signals for Mobile Devices.

As touch based input becomes more popular in mobile devices, there is an increasing need for haptic feedback on key-less input surface. Four experiments were conducted to design and evaluate identifiable emulated key-click signals using a piezoelectric actuator. Experiments I and II assessed the information transmission capacity for the amplitude, frequency, and number of cycles of raised cosine waveforms used to drive the piezo actuators under fixed- and roving-background conditions, respectively. Experiment III estimated the total information transfer for all three parameters. The results were used to reduce the number of stimulus alternatives in the key-click signal set with the goal to achieve perfect identification performance. Experiment IV verified that up to 5 to 6 identifiable key-click signals could be achieved with the experimental setup. The present study outlines an information theoretic approach to conducting identification experiments to guide the design of and to evaluate a perfectly identifiable stimulus set. The methodology can be applied to other applications in need of perceptually identifiable stimulation patterns.

Generalized relative entropies and the capacity of classical-quantum channels

We provide lower and upper bounds on the information transmission capacity of one single use of a classical-quantum channel. The lower bound is expressed in terms of the Hoeffding capacity, which we define similarly to the Holevo capacity but replacing the relative entropy with the Hoeffding distance. Similarly, our upper bound is in terms of a quantity obtained by replacing the relative entropy with the recently introduced max-relative entropy in the definition of the divergence radius of a channel.

Geospatial Remote Sensing Using Advanced Sensor Systems

ABSTRACTRecently, various nanoscale materials, devices, and systems with remarkable properties have been developed, with numerous unique applications in chem.-bio sensors, nanophotonics, and nanobiotechnology. This presentation covers satellite and aerial remote sensing science and methodologies employing nanotechnology based advanced sensor systems to improve performance, resolutions, and security. Increased demand on monitoring, surveillance due to global war on terrorism, weather prediction, and environmental pollution detection and monitoring have necessitated geospatial sensing with high accuracy, speed, and authenticity. Plasmonic interactions on the nanoscale and nanophotonics have produced new phenomena and technologies surpassing the realms of possibilities with conventional photonics and electronics. These new technologies could include high spatial resolution near-field imaging, high efficiency information processing and transferring, high capacity optical data storage, flexible- and high contrast displays, and precise detection, control and manipulation of nanoscale devices and integrated systems. Elements utilizing refractive or diffractive surfaces have found applications in novel sub-wavelength nanostructures satellites. The nanophotonics structures coupled with lightweight structures and advanced nanotechnology based sensors have resulted in launching of nano-satellites by several countries. The use of nanophotonics in space through the combination of micro, nano, integrated and fibre-optic technologies is to reduce susceptibility of the system to EMI, reduction in the weight of the signal cables (&lt; 1/20 of electrical), higher information transmission capacity (GHz), reduced weight and volume, opto-isolation of critical spacecraft subsystems, high speed optical processing of RF and microwave signals, low propagation loss, and enhanced security encryption capabilities. Carbon Nanotubes (CNTs) based field emission electron gun (FEG) employ low voltage for emission and are actively researched as cold cathode microwave generation devices. CNTs based composites provide light-weight and compact platform with mechanical and thermal robustness. Such satellite system can be placed in low Earth orbit (LEO) to medium Earth orbit (MEO) as multi-sensor satellite imagers with panchromatic, multi-spectral, area and hyper spectral sensors on a single focal plane array (FPA), to achieve medium to high resolution (2.5m to 15m) spatial sampling, wide swaths (up to 45km) and noise equivalent reflectance (NER) values of less than 0.5%. An evaluation of security risks, vulnerability, and strategies is presented for communications technologies used in gathering, processing, storing, and disseminating global environmental micro and nano sensors and satellite data.

Interfirm Collaboration Networks: The Impact of Large-Scale Network Structure on Firm Innovation

The structure of alliance networks influences their potential for knowledge creation. Dense local clustering provides information transmission capacity in the network by fostering communication and cooperation. Nonredundant connections contract the distance between firms and give the network greater reach by tapping a wider range of knowledge resources. We propose that firms embedded in alliance networks that exhibit both high clustering and high reach (short average path lengths to a wide range of firms) will have greater innovative output than firms in networks that do not exhibit these characteristics. We find support for this proposition in a longitudinal study of the patent performance of 1,106 firms in 11 industry-level alliance networks.

Controlled dense coding for continuous variables using three-particle entangled states

In the development of theoretical and experimental studies of quantum information, the quantum teleportation that is the disembodied transport of an unknown quantum state from a sender to a remote receiver @1# and the dense coding in which the single bit sent from a sender to a receiver can successfully carry two bits of classical information @2#, have attracted extensive interests. The nonlocal quantum entanglement plays a determinant role in the quantum information processing. Towards possible applications in quantum communication, both theoretical and experimental investigations increasingly focus on quantum states of continuous variables in an infinite-dimensional Hilbert space, since the EinsteinPodolsky-Rosen ~EPR! entangled state can be efficiently generated using squeezed light and beam splitters, for instance, the entangled EPR pairs resulting from two-mode squeezed vacuum state have been successfully employed in demonstrating unconditional quantum teleportation @3#. Later, the schemes realizing highly efficient dense coding for continuous variables are theoretically proposed, in which the two-mode squeezed-state entanglement is utilized to achieve unconditional signal transmission @4–6#. The bright EPR beams have been experimentally produced with a nondegenerate optical parametric amplifier ~NOPA! @7# and the dense coding for continuous variables based on bright EPR beam has been demonstrated initially @8#. Loock and Braunstein have given that the superposition of more than independently squeezed states can yield multipartite entanglement for continuous variables and presented the scheme of quantum teleportation using entangled three-mode state @9#. The fidelity in this scheme depends on the measurement of the third particle. Controlled dense coding for discrete variables was proposed recently using the Greenberger-Horne-Zeilinger state ~GHZ! @10#. Inspired by the similarity and difference between dense coding and quantum teleportation, in this paper we study dense coding using the tripartite entangled state. It is shown that when using the tripartite entangled state, the information transmission capacity of dense coding is controlled by the measurement of the third particle. We introduce a simple, experimentally realizable, controlled dense coding protocol for continuous variables by exploring nondegenerate optical parametric amplifier. Due to adopting the

Universal quantum limits on single-channel information, entropy, and heat flow

We show that the recently discovered universal upper bound on the thermal conductance of a single channel comprising particles obeying arbitrary fractional statistics is in fact a consequence of a more general universal upper bound, involving the averaged entropy and energy currents of a single channel connecting heat reservoirs with arbitrary temperatures and chemical potentials. The latter upper bound in turn leads, via Holevo's theorem, to a universal (i.e., statistics independent) upper bound on the optimum capacity for classical information transmission down a single, wideband quantum channel.

Von Neumann capacity of noisy quantum channels

We discuss the capacity of quantum channels for information transmission and storage. Quantum channels have dual uses: they can be used to transmit known quantum states which code for classical information, and they can be used in a purely quantum manner, for transmitting or storing quantum entanglement. We propose here a definition of the von Neumann capacity of quantum channels, which is a quantum-mechanical extension of the Shannon capacity and reverts to it in the classical limit. As such, the von Neumann capacity assumes the role of a classical or quantum capacity depending on the usage of the channel. In analogy to the classical construction, this capacity is defined as the maximum von Neumann mutual entropy processed by the channel, a measure which reduces to the capacity for classical information transmission through quantum channels (the ``Kholevo capacity'') when known quantum states are sent. The quantum mutual entropy fulfills all basic requirements for a measure of information, and observes quantum data-processing inequalities. We also derive a quantum Fano inequality relating the quantum loss of the channel to the fidelity of the quantum code. The quantities introduced are calculated explicitly for the quantum depolarizing channel. The von Neumann capacity is interpreted within the context of superdense coding, and an extended Hamming bound is derived that is consistent with that capacity.

Specialised acousto-optical processor for input, display, and coherent-optical processing of multiparameter information from spaceborne telemetric systems

An acousto-optical system for input, display, and coherent-optical processing of information was implemented experimentally. The information transmission capacity, the structure of the information fluxes, and the efficiency of spaceborne telemetric systems were taken into account. The number of equivalent frequency-resolved channels corresponded to the structure of a telemetric frame of a two-step switch. The number of intensity levels of laser radiation corresponded to the scale of changes in the parameters. Use was made of the technology of a liquid optical contact between a wedge-shaped piezoelectric transducer made of lithium niobate and an anisotropic light-and-sound guide made of paratellurite with asymmetric scattering geometry. The simplest technique for optical filtering of multiparameter signals was analysed.

Ultimate information carrying limit of quantum systems.

The possible amount of information transfer between any source and any user via a quantum system is bounded through the quantum entropy function. In contrast to the classical case, this shows that infinite information transfer implies infinite entropy. The entropy bound is also applied to obtain the ultimate quantum information transmission capacity of the free electromagnetic field under a power and a bandwidth constraint.

The information capacity of the human motor system in controlling the amplitude of movement. 1954.

Information theory has recently been employed to specify more precisely than has hitherto been possible man's capacity in certain sensory, perceptual, and perceptual-motor functions (5, 10, 13, 15, 17, 18). The experiments reported in the present paper extend the theory to the human motor system. The applicability of only the basic concepts, amount of information, noise, channel capacity, and rate of information transmission, will be examined at this time. General familiarity with these concepts as formulated by recent writers (4, 11,20, 22) is assumed. Strictly speaking, we cannot study man's motor system at the behavioral level in isolation from its associated sensory mechanisms. We can only analyze the behavior of the entire receptor-neural-effector system. However, by asking 51 to make rapid and uniform responses that have been highly overlearned, and by holding all relevant stimulus conditions constant with the exception of those resulting from 5s own movements, we can create an experimental situation in which it is reasonable to assume that performance is limited primarily by the capacity of the motor system. The motor system in the present case is defined as including the visual and proprioceptive feedback loops that permit S to monitor his own activity. The information capacity of the motor system is specified by its ability to produce consistently one class of movement from among several alternative movement classes. The greater the number of alternative classes, the greater is the information capacity of a particular type of response. Since measurable aspects of motor responses, such as their force, direction, and amplitude, are continuous variables, their information capacity is limited only by the amount of statistical variability, or noise, that is characteristic of repeated efforts to produce the same response. The information capacity of the motor Editor's Note. This article is a reprint of an original work published in 1954 in the Journal of Experimental Psychology, 47, 381391.

Information capacity of additive white gaussian noise channel with practical constraints

The paper describes the determination of the additive white Gaussian noise channel information transmission capacity when the channel input and output are limited by certain constraints. The channel input constraints are those of signal amplitude, or signal amplitude and average power. The input signal amplitude and average power constraints are defined by restricting the channel input to values within the finite interval [—A, + A] and also to have average power equal to some specified value. The channel output constraint is that of signal clipping due to quantisation applied at the receiver. The input signal amplitude/output signal clipping constrained capacity, and the input signal amplitude and average power/output signal clipping constrained capacity are determined separately. It is found that there are unique, optimum and discrete input signal amplitude distributions, taking a finite number of values, and optimum output signal clippings that achieve these capacity values. The optimum input distribution values are also used to determine the optimum amplitude probability density function at the channel output.

Novel Techniques for Counteracting Multipath Interference Effects in Receiving Systems

Discrete maltipath propagation is generally considered to impose severe limitations on the performance of receiving systems, and hence, on the information transmission capacity of a communication link. Much work has been directed to the problems of relieving multipath effects, generally concentrating on correction of the performance realized with the resultant of the multiple-path outputs. In this paper, the emphasis is on separating the outputs of a small number of discrete paths not only for freeing the output of at least one usable path, but also possibly for combining the various path outputs in constructive ways to take advantage of the additional signal energy that each path provides. Novel techniques for accomplishing this are described, based on converting directional and propagation-delay differences into very distinctive frequency differences by synthetic Doppler methods. These techniques are of course applicable to facilitate the separation of various time and frequency overlapping signals arriving from different directions.

Operational Limitations of Charge Transfer Devices

The incomplete transfer of charge and the existence of random noise lead to the primary operational limitations of charge transfer devices. Owing to the signal dependence of the residual charge, which accumulates as a result of the incomplete transfer, signal detection with static detection levels becomes seriously impaired before the onset of significant signal attenuation or noise degradation. A scheme using dynamic detection levels is found to greatly extend the operational range of CTD's and achieves the minimum possible error rate for detecting uncorrelated charge packet sizes. By contrast, simple coding procedures are found to be ineffective in overcoming signal degradation due to incomplete transfer. Shannon's expression for maximum information transmission capacity is transformed into an expression for maximum information storage capacity. It is found that significantly larger storage capacities are possible with CTD's than have been achieved.

Studies on Periodic Signals in CNS Cells Under Spontaneous and Driven Conditions

This presentation summarizes work done during the past years on periodic signals recorded in the spontaneous activity of brain cells and in responses to stimuli. In some CNS cells periodic signals appear spontaneously or in responses to stimuli which are not periodic in nature. However, such periodic signals appear to possess information transmission capacity in sensory tissues only if they are part of a synchronous population response. A periodic signal in a brain cell is not likely to be transmitted across a synapse unless it arrives at the post-synaptic cell through other routes in the same phase.