Signal Cables Research Articles

MRI dynamic range and its compatibility with signal transmission media

As the number of MRI phased array coil elements grows, interactions among cables connecting them to the system receiver become increasingly problematic. Fiber optic or wireless links would reduce electromagnetic interference, but their dynamic range (DR) is generally less than that of coaxial cables. Raw MRI signals, however, have a large DR because of the high signal amplitude near the center of k-space. Here, we study DR in MRI in order to determine the compatibility of MRI multicoil imaging with non-coaxial cable signal transmission. Since raw signal data are routinely discarded, we have developed an improved method for estimating the DR of MRI signals from conventional magnitude images. Our results indicate that the DR of typical surface coil signals at 3 T for human subjects is less than 88 dB, even for three-dimensional acquisition protocols. Cardiac and spine coil arrays had a maximum DR of less than 75 dB and head coil arrays less than 88 dB. The DR derived from magnitude images is in good agreement with that measured from raw data. The results suggest that current analog fiber optic links, with a spurious-free DR of 60–70 dB at 500 kHz bandwidth, are not by themselves adequate for transmitting MRI data from volume or array coils with DR ∼90 dB. However, combining analog links with signal compression might make non-coaxial cable signal transmission viable.

Differential-outputB-dot andD-dot monitors for current and voltage measurements on a 20-MA, 3-MV pulsed-power accelerator

We have developed a system of differential-output monitors that diagnose current and voltage in the vacuum section of a 20-MA 3-MV pulsed-power accelerator. The system includes 62 gauges: 3 current and 6 voltage monitors that are fielded on each of the accelerator's 4 vacuum-insulator stacks, 6 current monitors on each of the accelerator's 4 outer magnetically insulated transmission lines (MITLs), and 2 current monitors on the accelerator's inner MITL. The inner-MITL monitors are located 6 cm from the axis of the load. Each of the stack and outer-MITL current monitors comprises two separate $B$-dot sensors, each of which consists of four 3-mm-diameter wire loops wound in series. The two sensors are separately located within adjacent cavities machined out of a single piece of copper. The high electrical conductivity of copper minimizes penetration of magnetic flux into the cavity walls, which minimizes changes in the sensitivity of the sensors on the 100-ns time scale of the accelerator's power pulse. A model of flux penetration has been developed and is used to correct (to first order) the $B$-dot signals for the penetration that does occur. The two sensors are designed to produce signals with opposite polarities; hence, each current monitor may be regarded as a single detector with differential outputs. Common-mode-noise rejection is achieved by combining these signals in a $50\mathrm{\text{\ensuremath{-}}}\ensuremath{\Omega}$ balun. The signal cables that connect the $B$-dot monitors to the balun are chosen to provide reasonable bandwidth and acceptable levels of Compton drive in the bremsstrahlung field of the accelerator. A single $50\mathrm{\text{\ensuremath{-}}}\ensuremath{\Omega}$ cable transmits the output signal of each balun to a double-wall screen room, where the signals are attenuated, digitized ($0.5\mathrm{\text{\ensuremath{-}}}\mathrm{ns}/\mathrm{sample}$), numerically compensated for cable losses, and numerically integrated. By contrast, each inner-MITL current monitor contains only a single $B$-dot sensor. These monitors are fielded in opposite-polarity pairs. The two signals from a pair are not combined in a balun; they are instead numerically processed for common-mode-noise rejection after digitization. All the current monitors are calibrated on a 76-cm-diameter axisymmetric radial transmission line that is driven by a 10-kA current pulse. The reference current is measured by a current-viewing resistor (CVR). The stack voltage monitors are also differential-output gauges, consisting of one 1.8-cm-diameter $D$-dot sensor and one null sensor. Hence, each voltage monitor is also a differential detector with two output signals, processed as described above. The voltage monitors are calibrated in situ at 1.5 MV on dedicated accelerator shots with a short-circuit load. Faraday's law of induction is used to generate the reference voltage: currents are obtained from calibrated outer-MITL $B$-dot monitors, and inductances from the system geometry. In this way, both current and voltage measurements are traceable to a single CVR. Dependable and consistent measurements are thus obtained with this system of calibrated diagnostics. On accelerator shots that deliver 22 MA to a low-impedance $z$-pinch load, the peak lineal current densities at the stack, outer-MITL, and inner-MITL monitor locations are 0.5, 1, and $58\text{ }\text{ }\mathrm{MA}/\mathrm{m}$, respectively. On such shots the peak currents measured at these three locations agree to within 1%.

Ionization Chamber with Remote Preamplifier for Automatic Exposure Systems Used in X-Ray Diagnosis

efficiency and exposure dose decrease in the X ray detec tor plane. The sensitivity of automatic exposure units of digital X ray imaging systems should be substantially increased [1]. The problem of sensitivity increase is made quite difficult by increased requirements for X ray trans parency of media located between patient and X ray input detector plane. According to GOST R IEC 61223 3 1 2001, the attenuation factor of automatic exposure dose control system detector is 1.11 [2]. Distance between patient plane and input X ray detector plane should be reduced to decrease X ray image geometric unsharpness and radiation load on patient. This can be achieved by reducing the ionization chamber width. Within the last decade, the ionization chamber width in X ray appara tuses was decreased from 12 10 to 6 mm against the back ground of virtually invariable sensitivity per area of meas ured (dominant) zone of the radiation detector. The sen sitivity losses were 30 40% and were compensated by low noise high sensitivity electronics. The sensitivity of the electronics increased by an order of magnitude during recent time. In automatic exposure units of digital X ray imaging systems, the ionization chamber is installed before the X ray radiation detector (X ray film cassettes or digital panel) and is connected to an automatic exposure system or to a preliminary amplifier using a signal cable. Possible schemes of ionization chamber connection to an auto matic exposure system are shown in Fig. 1. Connection version (Fig. 1a) was used in X ray apparatuses of the past century but is not used any longer. This is due to requirements for patient radiation load decrease and recent progress in enhancement of sensitiv ity of X ray apparatuses. Sensitivity of X ray detector (ionization chamber) should be increased adequately. A preamplifier installed near the ionization chamber pro vides an economical solution to this problem. Two con nection versions (Figs. 1b and 1c) are presently used. In the connection version shown in Fig. 1b, the preamplifi er is installed directly on the ionization chamber housing. In the connection version shown in Fig. 1c, the preampli fier is installed close to the ionization chamber. Advantages and disadvantages of these versions were dis cussed at length in [1]. Biomedical Engineering, Vol. 42, No. 5, 2008, pp. 236 238. Translated from Meditsinskaya Tekhnika, Vol. 42, No. 5, 2008, pp. 13 15. Original article submitted April 11, 2008.

Vulnerability of spacecraft harnesses to hypervelocity impacts

Abstract During a study performed in framework of a European Space Agency contract, the vulnerability of spacecraft harnesses has been assessed. The harnesses consisted of three different space-grade cable types: power cables, screened twisted pair data cables and radio frequency (RF) cables. They were alternately shielded by two different types of representative spacecraft structure walls. Ten hypervelocity impact (HVI) tests at 0° incidence have been performed with impact velocities ranging from 6.4 km/s to 7.7 km/s. Projectiles have been aluminium spheres with diameters ranging from 1.5 mm to 4.0 mm. During the tests, all cables were operated at their representative conditions and the disturbances, induced by the impacts, were measured. The malfunction observed could be related to two physical failure mechanisms: (1) short circuits caused by a conducting cloud of molten and evaporated aluminium and, for the data cables, (2) strands being bent by impacting fragments creating a short circuit between screen and signal cable. The influence of a more complex structure wall to the failure mechanism in (1) is shown. Malfunction was dependent on mechanical damage, but no clear correlation between severity of malfunction and mechanical damage could be established. The data cables were the most vulnerable cable, while the RF cables were the most robust. The disturbances recorded could pose a significant threat to connected electronic equipment. Examples of electrical performance are given.

A Railway Signal Control System by Optical LAN and Design Simplification

When replace railway interlocking devices, setting up of large number of signal cables and confirming of wiring connections are required. So, it is worried that serious transport disorder caused by human error in wiring works would occur. We have developed a railway signal control system utilized optical LAN to reduce the signal cables and wiring works. Moreover, all signal devices operate independently, designers have to handle all devices one by one and pay great attention to avoid causing harmful influence each other. We propose the data-driven method to make easy to replace interlocking device. This logic is rearranged according to the field device in order to simplify and decrease design duties of designers. In this paper, we introduce this system, and describe network transmission, safety-related communication and software configuration of the system.

RF Photonics

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In parallel with the development of fiber optics for transmission of digital information, the 1970s and 1980s saw the development of techniques for the transmission of wide-bandwidth analog radio-frequency (RF) signals over optical fibers. The simultaneous need for high linearity and high signal-to-noise in RF photonic links spurred the development of lasers, modulators and detectors matched to the special needs of such links. RF photonics was also explored for the processing of RF signals by means of optically implemented filters and variable-delay lines. Commercial applications of RF photonics included cable television signal distribution and subcarrier-multiplexed digital signals. </para>

Retarding field analyzer for ion energy distribution measurements at a radio-frequency biased electrode

A retarding field energy analyzer designed to measure ion energy distributions impacting a radio-frequency biased electrode in a plasma discharge is examined. The analyzer is compact so that the need for differential pumping is avoided. The analyzer is designed to sit on the electrode surface, in place of the substrate, and the signal cables are fed out through the reactor side port. This prevents the need for modifications to the rf electrode--as is normally the case for analyzers built into such electrodes. The capabilities of the analyzer are demonstrated through experiments with various electrode bias conditions in an inductively coupled plasma reactor. The electrode is initially grounded and the measured distributions are validated with the Langmuir probe measurements of the plasma potential. Ion energy distributions are then given for various rf bias voltage levels, discharge pressures, rf bias frequencies--500 kHz to 30 MHz, and rf bias waveforms--sinusoidal, square, and dual frequency.

The JIP1 Scaffold Protein Regulates Axonal Development in Cortical Neurons

SummaryThe development of neuronal polarity is essential for the determination of neuron connectivity and for correct brain function. The c-Jun N-terminal kinase (JNK)-interacting protein-1 (JIP1) is highly expressed in neurons and has previously been characterized as a regulator of JNK signaling. JIP1 has been shown to localize to neurites in various neuronal models, but the functional significance of this localization is not fully understood [1–4]. JIP1 is also a cargo of the motor protein kinesin-1, which is important for axonal transport [2, 4]. Here we demonstrate that before primary cortical neurons become polarized, JIP1 specifically localizes to a single neurite and that after axonal specification, it accumulates in the emerging axon. JIP1 is necessary for normal axonal development and promotes axonal growth dependent upon its binding to kinesin-1 and via a newly described interaction with the c-Abl tyrosine kinase. JIP1 associates with and is phosphorylated by c-Abl, and the mutation of the c-Abl phosphorylation site on JIP1 abrogates its ability to promote axonal growth. JIP1 is therefore an important regulator of axonal development and is a key target of c-Abl-dependent pathways that control axonal growth.

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.

Phosphorylation of c-Abl by Protein Kinase Pak2 Regulates Differential Binding of ABI2 and CRK

The tyrosine kinase c-Abl is implicated in a variety of cellular processes that are tightly regulated by c-Abl kinase activity and/or by interactions between c-Abl and other signaling molecules. The interaction of c-Abl with the Abl interactor protein Abi2 is shown to be negatively regulated by phosphorylation of serines 637 and 638. These serines are adjacent to the PxxP motif (PTPPKRS637S638SFR) that binds the SH3 domain of Abi. Phosphorylation of the Abl 593-730 fragment by Pak2 dramatically reduces Abi2 binding ( approximately 90%). Mutation of serines 637-639 to alanine (3A) or aspartate (3D) results in an increased tyrosine kinase activity of c-Abl 3D, and a slight reduction of the activity of the 3A mutant, as compared to wild-type (WT) c-Abl. The interaction between Abi2 and c-Abl 3D is inhibited by 80%, as compared to WT c-Abl or c-Abl 3A. This is accompanied by a 2-fold increase in binding of Crk to c-Abl 3D. The data indicate a molecular mechanism whereby phosphorylation of c-Abl by Pak2 inhibits the interaction between the SH3 domain of Abi2 and the PxxP motif of c-Abl. This phosphorylation enhances the association of c-Abl with the substrate Crk and increases c-Abl-mediated phosphorylation of Crk, thus altering the association of Crk with other signaling molecules.

Titan: A new facility for ultraclean sampling of trace elements and isotopes in the deep oceans in the international Geotraces program

Towards more rapid ultraclean sampling of deep ocean waters for trace elements, a novel rectangular frame was constructed of titanium, holding two rows of 12 samplers, as well as various sensors. The frame is deployed to deep ocean waters by an 8000 m length Kevlar wire with internal power and signal cables. Closing of each sampler is by seawater hydraulics via silicone tubings connecting each sampler with a central 24 position Multivalve. Upon recovery the complete frame with 24 samplers is placed inside an ultraclean laboratory van, where water is drawn via filters into bottles. Previously the clean sampling of ocean waters has been very time-consuming by attachment of individual ultraclean bottle samplers one by one to a metal-free (e.g. all-Kevlar) hydrowire. The novel Titan system is 3–4 times faster and permits routine collection of deep ocean sections while economizing required shiptime. In a test of the new system in November 2005 in the Canary Basin excellent low dissolved Fe concentrations (∼ 0.1 to ∼ 0.4 nM) are consistent with values obtained of individual samplers on a simple wire, and previous values in a pilot study of 2002 in the same basin, as well as published dissolved Fe values elsewhere in the northeast Atlantic Ocean.

Development of Network Plug-in Actuator

We propose an intelligent connector (ICN) that uses a network plug-in actuator (NPA) or an intelligent connector (ICN) to reduce the number of signal and power cables and integrates an AC servomotor and motor drive with serial signal wires using a controller area Network (CAN). The ICN connects the NPA and a controller such as a personal computer and connects different networks such as the Ethernet, CAN, IEEE1394, or USB. We developed an NPA series from 5 W to 750 W and verified their functions. We also evaluated the ICN performance using the NPA. This system was installed on an “econovehicle” and its effectiveness was successfully demonstrated.

Analog integrator for the Korea superconducting tokamak advanced research magnetic diagnostics

An analog integrator, which automatically compensates an integrating drift, has been developed for the magnetic diagnostics in the Korea superconducting tokamak advanced research (KSTAR). The compensation of the drift is done by the analog to digital converter-register-digital to analog converter in the integrator. The integrator will be used in the equilibrium magnetic field measurements by using inductive magnetic sensors during a plasma discharge in the KSTAR machine. Two differential amplifiers are added to the signal path between each magnetic sensor and the integrator in order to improve the performance of the integrator because a long signal cable of 100 m will be used for the measurement in the KSTAR machine. In this work, the characteristics of the integrator with two differential amplifiers are experimentally investigated.

P1692 Environmental decontamination of an intensive care unit to control outbreaks of multidrug-resistant Gram-negative rods using hydrogen peroxide vapour

In this mini-review, various aspects of homeostasis of microbial cells and its perturbation by antimicrobial agents will be discussed. First, outlining the position that the physiological studies on microbial behaviour using the modern molecular tools should have in food science sets the scene for the studies. Subsequently, the advent of functional genomics is discussed that allows full coverage of cellular reactions at unprecedented levels. Examples of weak organic acid resistance, the stress response against natural antimicrobial agents and responses against physicochemical factors show how we can now “open the black box” that microbes are, look inside and begin to understand how different cellular signalling cables are wired together. Using the analogy with machines, it will be indicated how the use of various signalling systems depends on the availability of substrates “fuel” to let the systems act in the context of the minimum energetic requirement cells have to let their housekeeping systems run. The outlook illustrates how new insights might be used to device knowledge-based rather than empirical combinations of preservation systems and how risk assessment models might be deviced that link the mechanistic insight to risk distributions of events in food manufacturing.

Acetaldehyde Inhibits PPARγ via H 2O 2-Mediated c-Abl Activation in Human Hepatic Stellate Cells

Accumulating evidence indicates that acetaldehyde (AcCHO) is one of the main mediators of fibrogenesis in alcoholic liver disease. AcCHO stimulates synthesis of fibrillar collagens in hepatic stellate cells, but the molecular events directly involved in the activation of collagen genes are debatable. Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor that is expressed in stellate cells, and its activation by specific ligands inhibits collagen synthesis. In this study, we evaluated the effects of AcCHO on PPARgamma transcriptional activity and its correlation with the AcCHO-induced collagen synthesis in hepatic stellate cells. AcCHO treatment inhibited ligand-dependent and -independent PPARgamma transcriptional activity, and this effect was correlated with an increased phosphorylation of a mitogen-activated protein kinase site at serine 84 of the human PPARgamma. Transfection of the PPARgammaSer84Ala mutant completely prevented the effect of AcCHO on PPARgamma activity and in parallel abrogated the induction of collagen gene expression by AcCHO. The effect of AcCHO on PPARgamma activity and phosphorylation was blocked by extracellular signal-regulated kinase (ERK) 1/2 and protein kinase C (PKC)delta inhibitors as well as by catalase, suggesting that hydrogen peroxide is involved in the molecular cascade responsible for PPARgamma phosphorylation via activation of the PKCdelta/ERK pathway. Furthermore, inhibition of c-Abl completely abrogated the effect of AcCHO on either PPARgamma function or collagen synthesis; in addition, expression of the PPARgammaSer84Ala mutant prevented the profibrogenic signals mediated by c-Abl activation. Our results showed that the induction of collagen expression by AcCHO in stellate cells is dependent on PPARgamma phosphorylation induced by a hydrogen peroxide-mediated activation of the profibrogenic c-Abl signaling pathway.

Development of a miniature uniaxial pressure-acceleration probe for bioacoustic applications

The bioacoustics community has recently expressed an interest in using collocated measurements of the acoustic pressure and the particle velocity to categorize how certain species of marine life transmit and receive sound. For most applications the frequency range of interest spans from tens of hertz to a few kilohertz. Because the test specimens and the test facilities can be relatively small, a miniature pressure-acceleration (b−a) probe was developed. The probe conforms to the geometry of a cube having a principal side length of 31.75 mm (1.25 in.) and contains flexural mode piezoelectric transducers to measure the acoustic pressure and one component of the acoustic particle acceleration vector. The cube also houses a low-noise two-channel preamplifier and is compliantly suspended inside a light frame. This paper highlights the design evolution of a few prototypes and addresses issues associated with the electronic noise floor of the accelerometer, mechanical cross talk between the transducers, damping of the external suspension system and transducers, and the dynamics of the signal cable. [Work supported by Acoustech Corporation IR&amp;D.]

Insulated Joint for Corrosion Protection of Buried Subway Gallery Structure: Consideration on Cable Ground Connection

Protection against corrosion of a subway's metallic structure can be performed by insulated joints at the interface between galleries and stations. A preliminary analysis shows some differences in stray current flowing and a possible improvement of protection depending on the joint region configuration. This analysis is performed by means of a commercial three-dimensional finite-element method. A consequence of using insulated joints is a suitable grounding of the sheaths belonging to power and signal cables laying inside the gallery and particular care in connecting them to ground electrical masses or other metallic structures in order to avoid shunting insulated joints. Induced voltages and currents must be predicted to avoid any danger in both under-rated and fault conditions.

A Low-Crosstalk Design of 1.25 Gbps Optical Triplexer Module for FTTH Systems

In this paper, we analyzed and measured the electrical crosstalk characteristics of a 1.25 Gbps triplexer module for Ethernet passive optical networks to realize fiber-to-the-home services. Electrical crosstalk characteristic of the 1.25 Gbps optical triplexer module on a resistive silicon substrate should be more serious than on a dielectric substrate. Consequently, using the finite element method, we analyze the electrical crosstalk phenomena and propose a silicon substrate structure with a dummy ground line that is the simplest low-crosstalk layout configuration in the 1.25 Gbps optical triplexer module. The triplexer module consists of a laser diode as a transmitter, a digital photodetector as a digital data receiver, and an analog photodetector as a cable television signal receiver. According to IEEE 802.3ah and ITU-T G.9833, the digital receiver and analog receiver sensitivities have to meet -24 dBm at BER=10 -12 and -7.7 dBm at 44 dB SNR. The electrical crosstalk levels have to maintain less than -86 dB from DC to 3 GHz. From analysis and measurement results, the proposed silicon substrate structure that contains the dummy line with 100 μm space from the signal lines and 4 mm separations among the devices satisfies the electrical crosstalk level compared to a simple structure. This proposed structure can be easily implemented with design convenience and greatly reduce the silicon substrate size by about 50 %.

Cold electronics for the liquid argon hadronic end-cap calorimeter of ATLAS

This paper describes the on-detector electronics of the ATLAS hadronic end-cap calorimeter (HEC). The electronics is operated in liquid argon; therefore attention is paid to its performance at low temperatures. The core of the electronics are Gallium Arsenide (GaAs) preamplifiers. We present design, layout and results of various tests of the preamplifier chips and summing boards. The calibration and signal cables have been studied under laboratory conditions and the signal distortion is modeled. All parts of the electronics have been produced, tested and assembled on the calorimeter modules. The summary of the commissioning tests is presented.

An Investigation Into Measurement of Handset Antennas

This paper describes the investigation into the effects of signal cables on the operating frequencies, radiation patterns, and gains of handset antennas under test by using a proposed testing scheme. In this simple testing method, a coaxial signal cable feeds the handset antenna under test through a microstrip transmission-line etched onto a printed circuit board. The studies of the influences of different feeding schemes and cable arrangements on two commonly used handset antennas are carried out experimentally and numerically. Also, the distributions of the fields close to the antenna, handset chassis, and the cable are measured and simulated to explore the cable-related influences.