Multichannel biotelemetry.

A summary of considerations for design and application of multichannel biotelemetry systems is given. The advantages but also the problems of wired, wireless, combined and storage telemetry are discussed in connection with its application. Modulation and multiplexing techniques are described extensively; however, this review focuses not only on the transmission of biological data but also on the important aspects of connection of the transmission equipment to the biological subject and display of the biological information. The topic of multichannel biotelemetry is rounded off by a few additional subjects such as telecontrol, information source and classification.     

Multichannel electrochemical microbial detection unit.

A compact multichannel unit for electrochemical detection of microorganisms that automatically displays detection time length is described. This unit was successfully tested with various members of the Enterobacteriaceae group.     

Multichannel electrochemical microbial detection unit.

A compact multichannel unit for electrochemical detection of microorganisms that automatically displays detection time length is described. This unit was successfully tested with various members of the Enterobacteriaceae group.     

Multichannel thin-film electrode for intramuscular electromyographic recordings.

It is currently not possible to record electromyographic (EMG) signals from many locations concurrently inside the muscle in a single wire electrode system. We developed a thin-film wire electrode system for multichannel intramuscular EMG recordings. The system was fabricated using a micromachining process, with a silicon wafer as production platform for polyimide-based electrodes. In the current prototype, the flexible polymer structure is 220 microm wide, 10 microm thick, and 1.5 cm long, and it has eight circular platinum-platinum chloride recording sites of 40-microm diameter distributed along the front and back surfaces with 1,500-microm intersite spacing. The system prototype was tested in six experiments where the electrode was implanted into the medial head of the gastrocnemius muscle of rabbits, perpendicular to the pennation angle of the muscle fibers. Asynchronous motor unit activity was induced by eliciting the withdrawal reflex or sequential crushes of the sciatic nerve using a pair of forceps. Sixty-seven motor units were identified from these recordings. In the bandwidth 200 Hz to 5 kHz, the peak-to-peak amplitude of the action potentials of the detected motor units was 75 +/- 12 muV and the root mean square of the noise was 1.6 +/- 0.4 muV. The noise level and amplitude of the action potentials were similar for measures separated by up to 40 min. The experimental tests demonstrated that thin film is a promising technology for a new type of flexible-wire intramuscular EMG recording system with multiple detection sites.     

Multichannel recordings from membranes which contain gap junctions.

We have studied multichannel patch-clamp recordings in earthworm axon septal membranes that contain gap junctions. Though all channels have the same conductance and selectivity, the probabilities of the conductance levels in the majority of the recordings could not be fit by assuming independent and identical channels; in these cases, we found that at least two different open probabilities were required to explain the data. The data thus suggest that, within one junctional membrane complex, there exists a heterogenous channel population of similar but not identical channel types. The analysis also revealed cases where cooperativity between individual channels was the only explanation for the amplitude histograms of the observed multichannel activity. The conclusions drawn are based on a theoretical analysis of multichannel current-amplitude histograms. We derive two tests for independent and identical channels. We analyze the effects of mode shifting. These results are based on the ratio of peaks in the histograms; they are independent of the number of channels in the patch and the model of channel gating. In some cases failure to fulfill the criteria of these tests implied an interdependence or cooperativity between channels. Lastly, we have devised statistical tests for stability of the recording in the presence of variance due to finite sample size.     

Multichannel subcarrier ECG, respiration, and temperature biotelemetry system.

A three-channel biotelemetry system measuring ECG, respiration, and body temperature is described. The transmitter employs a 6-kHz subcarrier oscillator and is small enough for surgical implantation in animals the size of rats or larger. The frequency modulated 6-kHz tone from the reciver can be demodulated directly or recorded on an inexpensive cassette tape recorder for future analysis. The transmitter cost is approximately $35.00 and measures 3 times 1 cm. A battery life of several weeks and transmitter range of 10-100 m is typical. Transmission is on the FM broadcast band (88-108 MHz) and reception from an inexpensive FM portable receiver is possible.     

Multichannel recordings from membranes which contain gap junctions. II. Substates and conductance shifts.

Substates which can last up to several seconds are found in the 100-pS channel of the earthworm septum, a putative gap junction channel. The conductance of these substates is highly variable from preparation to preparation, and they are found at almost every fraction of the whole channel conductance. Another phenomenon seen in multichannel recordings is the "conductance shift": here the current passed by several open channels differs from an integral multiple of the current when only one channel is open. These shifts can be modelled by 1) a resistance in series with the channel or 2) long-lived substates. Each of these models fails in particular cases to explain either the magnitude or direction of the shifts. It is possible that both effects are simultaneously present.     

Multichannel transmission of proprioceptive input to motoneurons

A model has been developed to simulate the parallel channels of muscle spindles and their monosynaptic connections to a homonymous motoneuron in the turtle. Input to the model is muscle length and stimulation, output is motoneuronal membrane potential. Quality of transmission is greatly dependent upon dispersive properties of the system. The contributions of different dispersive features are compared and also cumulative effects are considered. Reference is made to conditions which are found in actual movements.     

Multichannel Compressive Sensing MRI Using Noiselet Encoding

The incoherence between measurement and sparsifying transform matrices and the restricted isometry property (RIP) of measurement matrix are two of the key factors in determining the performance of compressive sensing (CS). In CS-MRI, the randomly under-sampled Fourier matrix is used as the measurement matrix and the wavelet transform is usually used as sparsifying transform matrix. However, the incoherence between the randomly under-sampled Fourier matrix and the wavelet matrix is not optimal, which can deteriorate the performance of CS-MRI. Using the mathematical result that noiselets are maximally incoherent with wavelets, this paper introduces the noiselet unitary bases as the measurement matrix to improve the incoherence and RIP in CS-MRI. Based on an empirical RIP analysis that compares the multichannel noiselet and multichannel Fourier measurement matrices in CS-MRI, we propose a multichannel compressive sensing (MCS) framework to take the advantage of multichannel data acquisition used in MRI scanners. Simulations are presented in the MCS framework to compare the performance of noiselet encoding reconstructions and Fourier encoding reconstructions at different acceleration factors. The comparisons indicate that multichannel noiselet measurement matrix has better RIP than that of its Fourier counterpart, and that noiselet encoded MCS-MRI outperforms Fourier encoded MCS-MRI in preserving image resolution and can achieve higher acceleration factors. To demonstrate the feasibility of the proposed noiselet encoding scheme, a pulse sequences with tailored spatially selective RF excitation pulses was designed and implemented on a 3T scanner to acquire the data in the noiselet domain from a phantom and a human brain. The results indicate that noislet encoding preserves image resolution better than Fouirer encoding.     

Multichannel circular dichroism investigations of the structural stability of bacterial cytochrome P-450.

The thermal unfolding of cytochrome P-450 LIN and P-450 CAM measured in presence and absence of their specific substrates was analyzed by circular dichroism (CD) and the alpha-helix content was estimated. Both proteins show, independent of the presence or absence of the substrates, nearly the same amount of loss of the CD in the peptide region. The comparison of the half transition temperatures determined from different chromophores and different methods indicates a non-two-state transition of the thermal unfolding. For such analysis we developed a new spectrometer, which is capable of measuring the CD simultaneously at all wavelengths in a limited wavelength region.     

Multichannel vacuum arc discharge used for Z-pinch formation

Results are presented from experimental studies of the implosion dynamics and radiative characteristics of an aluminum Z-pinch formed from a plasma shell (PS). The PS with an initial diameter of 4 cm was produced with the help of a multichannel vacuum arc discharge and formed due to the evaporation of the electrode material in ten parallel arc discharges. The PS composition depended on the electrode material in the arc discharge. The described experiments were performed with aluminum electrodes. The total arc current was 80 kA. The PS implosion was provided by an IMRI-5 high-current generator with a current amplitude of 450 kA and rise time of 500 ns. The PS implosion resulted in the formation of a 0.2-cm-diameter plasma column with an electron temperature of 700?C900 eV and average ion density of (5?C8) × 10¹⁷ cm^?3. The maximum radiation power per unit length in aluminum K-lines reached 300 MW/cm, the duration of the radiation pulse being 20 ns.     

A Physiology-Based Seizure Detection System for Multichannel EEG

Background

Epilepsy is a common chronic neurological disorder characterized by recurrent unprovoked seizures. Electroencephalogram (EEG) signals play a critical role in the diagnosis of epilepsy. Multichannel EEGs contain more information than do single-channel EEGs. Automatic detection algorithms for spikes or seizures have traditionally been implemented on single-channel EEG, and algorithms for multichannel EEG are unavailable.

Methodology

This study proposes a physiology-based detection system for epileptic seizures that uses multichannel EEG signals. The proposed technique was tested on two EEG data sets acquired from 18 patients. Both unipolar and bipolar EEG signals were analyzed. We employed sample entropy (SampEn), statistical values, and concepts used in clinical neurophysiology (e.g., phase reversals and potential fields of a bipolar EEG) to extract the features. We further tested the performance of a genetic algorithm cascaded with a support vector machine and post-classification spike matching.

Principal Findings

We obtained 86.69% spike detection and 99.77% seizure detection for Data Set I. The detection system was further validated using the model trained by Data Set I on Data Set II. The system again showed high performance, with 91.18% detection of spikes and 99.22% seizure detection.

Conclusion

We report a de novo EEG classification system for seizure and spike detection on multichannel EEG that includes physiology-based knowledge to enhance the performance of this type of system.     

Multichannel Thomson scattering diagnostics for the GOL-3 facility

A multichannel Thomson scattering diagnostics for measuring the plasma parameters in the GOL-3 facility was designed and created at the Budker Institute of Nuclear Physics of the Siberian Division of the Russian Academy of Sciences. The diagnostics operates at the fundamental harmonic of a neodymium laser (1.06 μm) and allows one to perform measurements over a wide range of electron temperatures and densities with high spatial and time resolutions. A special multipulse oscillator is developed that makes it possible to perform up to 20 measurements of the plasma temperature and density over a period of 300 μs during one shot. The laser used to generate probing radiation, the recording system, and the calibration procedure are described. Results from measurements of the temporal evolution of the plasma density in the GOL-3 in different stages of the discharge are presented to illustrate the system operation. Original Russian Text ? S.V. Polosatkin, A.V. Burdakov, M.V. Ivantsivskiĭ, V.S. Koĭdan, V.K. Ovchar, A.F. Rovenskikh, V.V. Semionov, M.G. Fedotov, 2006, published in Fizika Plazmy, 2006, Vol. 32, No. 2, pp. 128–133.     

Multi-Reception Strategy with Improved SNR for Multichannel MR Imaging

A multi-reception strategy with extended GRAPPA is proposed in this work to improve MR imaging performance at ultra-high field MR systems with limited receiver channels. In this method, coil elements are separated to two or more groups under appropriate grouping criteria. Those groups are enabled in sequence for imaging first, and then parallel acquisition is performed to compensate for the redundant scan time caused by the multiple receptions. To efficiently reconstruct the data acquired from elements of each group, a specific extended GRAPPA was developed. This approach was evaluated by using a 16-element head array on a 7 Tesla whole-body MRI scanner with 8 receive channels. The in-vivo experiments demonstrate that with the same scan time, the 16-element array with twice receptions and acceleration rate of 2 can achieve significant SNR gain in the periphery area of the brain and keep nearly the same SNR in the center area over an eight-element array, which indicates the proposed multi-reception strategy and extended GRAPPA are feasible to improve image quality for MRI systems with limited receive channels. This study also suggests that it is advantageous for a MR system with N receiver channels to utilize a coil array with more than N elements if an appropriate acquisition strategy is applied.     

Multichannel plating unit for high-throughput plating of cell cultures

High-throughput genomic approaches to gene function or target identification have led to the development and implementation of the 96-well format for many standard molecular biology manipulations. The apparatus described here, a Multichannel Plating Unit, is designed to plate out individual cultures efficientlyfrom standard 96-well culture blocks. Following transformation, aliquots of culture are loaded onto sterile beads that are rolled along individual channels of agar media. After the beads traverse the channel, they drop into the exit alley for disposal via an exit pore. The apparatus presented has 12 individual lanes, and the spacing is compatible with a standard 12-channel pipettor Thus, the unit allows for the rapid plating of 12 individual cultures at a time. For one 96-well block of transformants, this method reduces the labeling and plating effort from 96 culture dishes that are spread individually to eight multichannel plates. The savings in time, materials, and storage space is significant     

Multichannel,Line-Monitoring Sensing Approach Based on Long-Range Surface Plasmons

The refractive index resolution of a surface plasmon resonance (SPR) sensor has been significantly improved these years; however, higher sensing performance is always desired. In this work, we propose a line-monitoring, long-range SPR sensor whose resolution is much better than conventional SPR sensors. Also, in contrast to mono-channel detection, multichannel detection, using line-monitoring technique, can detect multiple channels concurrently. In this way, this system achieves a refractive index resolution of 4.0?×?10^??7 refractive index units and can monitor multiple molecular interactions simultaneously. Finally, a model experiment detecting the Escherichia coli bacteria has demonstrated the potential for biomedical applications of this system.     

Multichannel Nature of Synthesis of Carbon Nanostructures in Low-Temperature Plasma

Plasma Physics Reports - Results of experimental investigation of the influence of C:H ratio in precursor composition on properties of carbon nanostructures synthesized in helium plasma jets are...     

Multichannel microspectrofluorometry for topographic and spectral analysis of NAD(P)H fluorescence in single living cells.

Starting from a previously described prototype microspectrofluorometer a more versatile apparatus has been developed with rapid optional operation on a topographic mode for the simultaneous multisite evaluation of NAD(P) reduction-reoxidation transients or on a spectral mode for the analysis of natural and exogenous fluorochromes, in single living cells. On the topographic mode, adetailed kinetic analysis of NAD or NAD P-linked dehydrogenases can be made from 50-100 cell points imultaneously via automatic recording of topographic scans upt to 16 times a second, in correlation with microelectrophoretic intracellular inuection of metabolites (e.g. nearly immediate response to glucose 6-phosphate, 20-25 s delay for 6-phosphogluconate). Rapid shifts from topographic to spectral operation make possible the detection of a change in fluorescence intensity at a specific intracellular site and the immediate verification of its nature (NAD(P)H or exogenous fluorochrome) by spectral observations.