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Feeding Network (feeding + network)

Distribution by Scientific Domains
Engineering71%

Selected Abstracts

Voltage-gated ionic currents in an identified modulatory cell type controlling molluscan feeding

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2002
Kevin Staras
Abstract An important modulatory cell type, found in all molluscan feeding networks, was investigated using two-electrode voltage- and current-clamp methods. In the cerebral giant cells of Lymnaea, a transient inward Na+ current was identified with activation at ,58 ± 2 mV. It was sensitive to tetrodotoxin only in high concentrations (, 50% block at 100 µm), a characteristic of Na+ channels in many molluscan neurons. A much smaller low-threshold persistent Na+ current (activation at <,,90 mV) was also identified. Two purely voltage-sensitive outward K+ currents were also found: (i) a transient A-current type which was activated at ,59 ± 4 mV and blocked by 4-aminopyridine; (ii) a sustained tetraethylammonium-sensitive delayed rectifier current which was activated at ,47 ± 2 mV. There was also evidence that a third, Ca2+ -activated, K+ channel made a contribution to the total outward current. No inwardly rectifying currents were found. Two Ca2+ currents were characterized: (i) a transient low-voltage (,65 ± 2 mV) activated T-type current, which was blocked in NiCl2 (2 mm) and was completely inactivated at ,,,50 mV; (ii) A sustained high voltage (,40 ± 1 mV) activated current, which was blocked in CdCl2 (100 µm) but not in ,-conotoxin GVIA (10 µm), ,-agatoxin IVA (500 nm) or nifedipine (10 µm). This current was enhanced in Ba2+ saline. Current-clamp experiments revealed how these different current types could define the membrane potential and firing properties of the cerebral giant cells, which are important in shaping the wide-acting modulatory influence of this neuron on the rest of the feeding network. [source]

A compact dual-element antenna array for adaptive MIMO system

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009
Xuan Wang
Abstract A novel compact dual-element antenna array is proposed for adaptive MIMO system. By four embedded PIN diodes in the feeding network, the antenna array has three different working states. It can operate as a dual-element antenna array or work as a single antenna while the unselected antenna is terminated to a lumped matched resistor. As a dual-element antenna array, it has a ,10 dB impedance bandwidth of 595 MHz covering UMTS band with mutual coupling lower than ,15 dB in the whole band. The measured radiation patterns show that the radiation property of the selected antenna keeps steady no matter the other antenna is selected or not. The proposed antenna array can achieve antenna selection scheme to adapt to the time-varying channel conditions. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 348,351, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24044 [source]

Wide coverage area of UHF-band RFID system using a pattern reconfigurable antenna

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2007
Hanphil Rhyu
Abstract A new type of a reader antenna for a UHF-band RFID system is proposed to cover a wider area. The proposed antenna consists of a circular polarized patch element, an omnidirectional electrical loop element, and a feeding network. By combining two antenna elements whose radiation patterns and half-power beamwidths (HPBW) are different from each other, the coverage area of the RFID system is increased. The experimental results show the proposed antenna has a HPBW of more than 120° and works well in the UHF band RFID system. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2154,2157, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22694 [source]

Design of a new wideband microstrip-fed circular slot antenna

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2006
Mohamed A. Habib
Abstract In this paper, a new ultra-wideband slot antenna with a simplified feeding network is presented. This antenna is composed of a circular slot coupled to a circular patch fed with 50, microstrip line. A proper parametric investigation was carried out for optimization of the proposed structure. Simulations and measurements show that a large bandwidth from 2.13 to 11.11 GHz can be achieved, which represents a relative bandwidth of 136.4%. Furthermore, good agreement between simulated and experimental results is obtained. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 919,923, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21519 [source]

Voltage-gated ionic currents in an identified modulatory cell type controlling molluscan feeding

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2002
Kevin Staras
Abstract An important modulatory cell type, found in all molluscan feeding networks, was investigated using two-electrode voltage- and current-clamp methods. In the cerebral giant cells of Lymnaea, a transient inward Na+ current was identified with activation at ,58 ± 2 mV. It was sensitive to tetrodotoxin only in high concentrations (, 50% block at 100 µm), a characteristic of Na+ channels in many molluscan neurons. A much smaller low-threshold persistent Na+ current (activation at <,,90 mV) was also identified. Two purely voltage-sensitive outward K+ currents were also found: (i) a transient A-current type which was activated at ,59 ± 4 mV and blocked by 4-aminopyridine; (ii) a sustained tetraethylammonium-sensitive delayed rectifier current which was activated at ,47 ± 2 mV. There was also evidence that a third, Ca2+ -activated, K+ channel made a contribution to the total outward current. No inwardly rectifying currents were found. Two Ca2+ currents were characterized: (i) a transient low-voltage (,65 ± 2 mV) activated T-type current, which was blocked in NiCl2 (2 mm) and was completely inactivated at ,,,50 mV; (ii) A sustained high voltage (,40 ± 1 mV) activated current, which was blocked in CdCl2 (100 µm) but not in ,-conotoxin GVIA (10 µm), ,-agatoxin IVA (500 nm) or nifedipine (10 µm). This current was enhanced in Ba2+ saline. Current-clamp experiments revealed how these different current types could define the membrane potential and firing properties of the cerebral giant cells, which are important in shaping the wide-acting modulatory influence of this neuron on the rest of the feeding network. [source]

Composite right/left handed artificial transmission line structures in CMOS for controlled insertion phase at 30 GHz

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2009
Symon K. Podilchak
Abstract Two CMOS integrated circuits are presented that utilize metamaterial composite right/left handed (CRLH) transmission lines (TLs) for zero insertion phase at 30 GHz. Specifically, 2 and 3 unit cell structures are presented with controlled insertion phase that is achieved by cascading lumped element capacitors and spiral inductors in an LC network configuration defining the TL unit cells. Furthermore, the fixed TL structures suggest the possibility of zero, advanced or delayed insertion phases by element variation, or by the use of simple active components. Simulation and measured results are in good agreement with CRLH TL theory, and display a linear insertion phase and flat group delay values that are dependent on the number of unit cells with an insertion loss of ,0.8 dB per cell. These findings suggest that such high speed CRLH TLs structures can be implemented for linear array feeding networks and compact antenna designs in CMOS at millimeter wave frequencies. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [source]

Design of waveguide microwave filters by means of artificial neural networks

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 6 2006
Antonio Luchetta
Abstract Cylindrical post-based waveguide filters are a relevant component of antenna feeding networks. Their synthesis performed via automatic optimization based on full-wave analyses can be very time consuming. In this article a novel fast-design approach based on Levy's and Moore's algorithms and an artificial neural network (ANN) architecture is presented. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006. [source]