Reliability Of Signal Transmission Research Articles

The extracellular matrix molecule brevican is an integral component of the machinery mediating fast synaptic transmission at the calyx of Held.

The proteoglycan brevican is a major component of the extracellular matrix of perineuronal nets and is highly enriched in the perisynaptic space suggesting a role for synaptic transmission. We have introduced the calyx of Held in the auditory brainstem as a model system to study the impact of brevican on dynamics and reliability of synaptic transmission. In vivo extracellular single-unit recordings at the calyx of Held in brevican-deficient mice yielded a significant increase in the action potential (AP) transmission delay and a prolongation of pre- and postsynaptic APs. The changes in dynamics of signal transmission were accompanied by the reduction of presynaptic vGlut1 and ultrastructural changes in the perisynaptic space. These data show that brevican is an important mediator of fast synaptic transmission at the calyx of Held. The extracellular matrix is an integral part of the neural tissue. Its most conspicuous manifestation in the brain are the perineuronal nets (PNs) which surround somata and proximal dendrites of distinct neuron types. The chondroitin sulfate proteoglycan brevican is a major component of PNs. In contrast to other PN-comprising proteoglycans (e.g. aggrecan and neurocan), brevican is mainly expressed in the perisynaptic space closely associated with both the pre- and postsynaptic membrane. This specific localization prompted the hypothesis that brevican might play a role in synaptic transmission. In the present study we specifically investigated the role of brevican in synaptic transmission at a central synapse, the calyx of Held in the medial nucleus of the trapezoid body, by the use of in vivo electrophysiology, immunohistochemistry, biochemistry and electron microscopy. In vivo extracellular single-unit recordings were acquired in brevican-deficient mice and the dynamics and reliability of synaptic transmission were compared to wild-type littermates. In knockout mice, the speed of pre-to-postsynaptic action potential (AP) transmission was reduced and the duration of the respective pre- and postsynaptic APs increased. The reliability of signal transmission, however, was not affected by the lack of brevican. The changes in dynamics of signal transmission were accompanied by the reduction of (i) presynaptic vGlut1 and (ii) the size of subsynaptic cavities. The present results suggest an essential role of brevican for the functionality of high-speed synaptic transmission at the calyx of Held.

Optimal size of stochastic Hodgkin-Huxley neuronal systems for maximal energy efficiency in coding pulse signals.

The generation and conduction of action potentials (APs) represents a fundamental means of communication in the nervous system and is a metabolically expensive process. In this paper, we investigate the energy efficiency of neural systems in transferring pulse signals with APs. By analytically solving a bistable neuron model that mimics the AP generation with a particle crossing the barrier of a double well, we find the optimal number of ion channels that maximizes the energy efficiency of a neuron. We also investigate the energy efficiency of a neuron population in which the input pulse signals are represented with synchronized spikes and read out with a downstream coincidence detector neuron. We find an optimal number of neurons in neuron population, as well as the number of ion channels in each neuron that maximizes the energy efficiency. The energy efficiency also depends on the characters of the input signals, e.g., the pulse strength and the interpulse intervals. These results are confirmed by computer simulation of the stochastic Hodgkin-Huxley model with a detailed description of the ion channel random gating. We argue that the tradeoff between signal transmission reliability and energy cost may influence the size of the neural systems when energy use is constrained.

On the Computation of the Higher Order Statistics of the Channel Capacity for Amplify-and-Forward Multihop Transmission

Higher order statistics (HOS) of the channel capacity provide useful information regarding the level of reliability of signal transmission at a particular rate. In this paper, we propose a novel and unified analysis, which is based on the moment-generating function (MGF) approach, to efficiently and accurately compute the HOS of the channel capacity for amplify-and-forward (AF) multihop transmission over generalized fading channels. More precisely, our easy-to-use and tractable mathematical formalism requires only the reciprocal MGFs of the transmission hop signal-to-noise ratio (SNR). Numerical and simulation results, which are performed to exemplify the usefulness of the proposed MGF-based analysis, are shown to be in perfect agreement.

A framework for enabling patient monitoring via mobile ad hoc network

A critical component of comprehensive patient monitoring is reliability in communication between the patients and the healthcare professionals without any time and location dependencies. Patient monitoring applications largely rely on infrastructure based wireless networks for signal transmission. However, infrastructure based wireless networks till date, suffer from unpredictable network coverage and have thus been attributed to the unpredictable communication reliability of patient monitoring applications. This research investigates an approach based on leveraging mobile ad hoc network to address the challenge of enhancing communication reliability in the context of patient monitoring. Mobile ad hoc network, formed among patient monitoring devices, has the potential of enhancing network coverage and enabling signal transmission from an area which has low or non-existent coverage from infrastructure based networks. In order to utilize mobile ad hoc network in the context of patient monitoring we propose (1) power management protocols that address the challenge of managing the low battery power of patient monitoring devices while maximizing communication reliability and (2) a framework that models the complex decision logic involved in leveraging mobile ad hoc network for diverse patient monitoring scenarios. Analytical evaluation of the proposed approach supports the premise that mobile ad hoc network formed among patient monitoring devices can enhance the reliability of signal transmission thereby improving the quality of patient monitoring applications. Technical and managerial implications of the research findings and the direction of future research are discussed.

The Intelligent Building Entrance Machine Design and Realization Based on the Ethernet

On the basis of Ethernet technology and intelligent building controlling technology, the intelligent building entrance machine based on Ethernet is designed. Different from the traditional entrance machine, the device does not require a dedicated audio and video signal lines. All signal transmission can be completed by only one cable. Significantly reduce the cost of cable, wiring costs and installation costs, and the accuracy and reliability of signal transmission.

室内可见光通信中的分数间隔均衡技术

The Fractionally Spaced Equalization(FSE) technology is investigated to mitigate the effects of Inter-symbol Interference(ISI) on the indoor Visible Light Communication(VLC) systems.Based on the propagation properties and signal modulation characteristics of indoor VLC systems,a link model for the indoor VLC communications is described,then the FSE method is proposed by using the link model.Furthermore,based on the minimum Mean Square Error(MSE) criterion,the FSE is optimized.Finally,the performance of the proposed FSE theory is evaluated by computer simulation.Experimental results indicate that the performance of T/2-fractionally spaced equalizer has improved 1-2 dB than that of the symbol interval equalizer in the same Bit Error Ratio(BER).It can eliminate the effects of the ISI induced by the multipath effectively,and can improve the reliability of signal transmission.

Research of Initiative Personnel Orientation and Rescue System in Mine based on Synchronous Signal Sensei Technology

According to shortcomings of short-distance signal recognition, low signal transmission reliability, high rate of leakage reading and single function that exist in current underground personnel orientation system, a new system based on Synchronous Signal Sensei with initiative RFID technology has been designed. The system's hardware and software is detailed designed including its working principle. The initiative communication process is realized by the SoC chip of nRF9E5. An emergency alarm circuit is added to the identification card. Based on the analysis of characteristics of underground wireless communication, a deep research was done to synchronous signal sensei technology and its realization process in order to reduce power consumption. Signal transmission mechanism is improved to return the correct confirm signal for once a time. The test results show that the communication distance between the card and the wireless location substation can reach 80m with 10 dBm of transmission power and 433.6MHz of communication frequency.

Noise-driven signal transmission using nonlinearity of VO2 thin films

We demonstrated signal transmission using the nonlinearity of VO2 in the manner of stochastic resonance (SR). A correlated insulator state of VO2 changes nonlinearly to a metallic state when an applied bias voltage increases beyond a threshold. The transition of the states between insulator and metal is adaptable to the SR theory. In this study, the response to a weak pulse signal was optimized by a particular level of noise via SR. Numerical SR simulations suggests the existence of multiple threshold channels in the insulating state, spontaneously enhancing the reliability of signal transmission.

Physical model for the width distribution of axons

The distribution of widths of axons was recently investigated, and was found to have a distinct peak at an optimized value. The optimized axon width at the peak may arise from the conflicting demands of minimizing energy consumption and assuring signal transmission reliability. The distribution around this optimized value is found to have a distinct non-Gaussian shape, with an exponential "tail". We propose here a mechanical model whereby this distribution arises from the interplay between the elastic energy of the membrane surrounding the axon core, the osmotic pressure induced by the neurofilaments inside the axon bulk, and active processes that remodel the microtubules and neurofilaments inside the axon. The axon's radius of curvature can be determined by the cell's control of the osmotic pressure difference across the membrane, the membrane tension or by changing the composition of the different components of the membrane. We find that the osmotic pressure, determined by the neurofilaments, seems to be the dominant control parameter.

Reliability improvement for an RFID-based psychiatric patient localization system

Collaboration between Field Generators, Readers and Tags generates the required functions in using radio frequency identification (RFID) for psychiatric patient localization. The Field Generator continually transmits trigger signals within its transmission range. When a Tag, which a patient wears, receives a trigger signal from a Field Generator, the Tag responds to a Reader with its own ID and ID of the Field Generator that issues the trigger. Based on Field Generator IDs that a Tag responds to, the location of the patient wearing the Tag can be estimated approximately. However, in recent RFID based localization systems, certain phenomena impact the reliability of signal transmission and decrease the feasibility of the localization system. To eliminate interference from different Field Generators, this study presents a novel graph coloring with merging and deletion (GCMD) algorithm for such a localization system that eliminates interference from Field Generators located near each other. Experimental results indicate that the GCMD algorithm significantly improves localization system reliability, thereby increasing the feasibility of RFID for psychiatric patient localization.

Motifs in gene transcription regulatory networks

A brief overview is given of the structure and evolution of gene transcription regulatory networks (GTRNs) of simple organisms like Escherichia coli and yeast Saccharomyces cerevisiae. A prominent motif appearing in the GTRNs is the feed forward loop (FFL). The FFLs have essential functions in gene regulatory processes and it is desirable that the operational noise of a FFL be kept at the minimum for reliability of signal transmission. We calculate the variances around the mean protein levels in the steady states of Type-1 and Type-4 coherent FFLs using a stochastic model of gene expression and the Langevin formalism. The Type-1 FFL is found to be less noisy than the Type-4 FFL. Type-1 FFL motif is more abundant than Type-4 FFL motif in GTRNs. This leads to the conjecture that noise is one of the evolvable traits on which natural selection acts.

Effect of correlations on signal transmission in a population of spiking neurons

Biological neurons are noisy. Nevertheless, they are able to transfer information in a very reliable manner. We address the problem of signal transmission reliability using a network of stochastic neurons of the integrate-and-fire type. We have derived an analytical expression of the noise power and the signal-to-noise ratio as a function of different network parameters. If firing times of different neurons are anticorrelated, signal transmission can be improved over a broad frequency range beyond the single-neuron firing rate.

Omega System Performance Assessment

The system availability index is defined as the probability that an Omega user can effectively utilize three or more Omega station signals with a properly functioning Omega receiving system at any location in the user's operating area (which may include the entire earth's surface) and at any time (hour/month/year). This index (denoted as PSA) has been developed to provide a probabilistic measure of system performance from the user's viewpoint and to provide a standard for evaluating the operational performance of the Omega system. The system availability model, used to compute PSA, is structured to address four system elements: (1) signal transmission reliability, (2) signal reception reliability, (3) signal coverage, and (4) regional priorities for Omega usage. Sample calculations and results are presented for assumed alternative station power level assignments to illustrate the numerical characteristics of PSA. Although the model is applied to the Omega system, the methodology presented in this paper is general and could be applied to other radionavigation systems. The development of the model/algorithm and the calculations performed to obtain the sample results were supported by the U.S. Coast Guard Omega Navigation System Center.