Science.gov

Sample records for channel antikaon-nucleon system

  1. SIDDHARTA results and implications of the results on antikaon-nucleon interaction

    NASA Astrophysics Data System (ADS)

    Marton, J.; Bazzi, M.; Beer, G.; Berucci, C.; Bellotti, G.; Bosnar, D.; Bragadireanu, A. M.; Cargnelli, M.; Clozza, A.; Curceanu, C.; Butt, A. Dawood; Fiorini, C.; Ghio, F.; Guaraldo, C.; Hayano, R.; Iliescu, M.; Iwasaki, M.; Sandri, P. Levi; Okada, S.; Pietreanu, D.; Piscicchia, K.; Vidal, A. Romero; Scordo, A.; Shi, H.; Sirghi, D. L.; Sirghi, F.; Tatsuno, H.; Doce, O. Vazquez; Widmann, E.; Zmeskal, J.

    2016-05-01

    The interaction of antikaons (K-) with nucleons and nuclei in the low-energy regime represents an active research field in hadron physics. There are important open questions like the existence of antikaon nuclear bound states like the prototype system being K- pp. Unique and rather direct experimental access to the antikaon-nucleon scattering lengths is provided by precision X-ray spectroscopy of transitions in low-lying states in light kaonic atoms like kaonic hydrogen and helium isotopes. In the SIDDHARTA experiment at the electron-positron collider DAΦNE of LNF-INFN we measured the most precise values of the strong interaction observables, i.e. the strong interaction on the 1s ground state of the electromagnetically bound K-p atom leading to energy shift and broadening of the 1s state. The SIDDHARTA result triggered new theoretical work, which achieved major progress in the understanding of the low-energy strong interaction with strangeness reflected by the antikaon-nucleon scattering lengths calculated with the K--proton amplitudes constrained by the SIDDHARTA data. The most important open question is the experimental determination of the hadronic energy shift and width of kaonic deuterium which is planned by the SIDDHARTA-2 Collaboration.

  2. A Cloudy Quark Bag Model of S, P, and D wave interactions for the coupled channel antikaon-nucleon system

    SciTech Connect

    He, Guangliang.

    1992-05-15

    The Cloudy Quark Bag Model is extended from S-wave to P- and D-wave. The parameters of the model are determined by K{sup {minus}}p scattering cross section data, K{sup {minus}}p {yields}{Sigma}{pi}{pi}{pi} production data, K{sup {minus}}p threshold branching ratio data, and K{sup {minus}}p {yields}{Lambda}{pi}{pi}{pi} production data. The resonance structure of the {Lambda}(1405), {Sigma}(1385), and {Lambda}(1520) are studied in the model. The shift and width of kaonic hydrogen are calculated using the model.

  3. Lattice QCD evidence that the Λ(1405) resonance is an antikaon-nucleon molecule.

    PubMed

    Hall, Jonathan M M; Kamleh, Waseem; Leinweber, Derek B; Menadue, Benjamin J; Owen, Benjamin J; Thomas, Anthony W; Young, Ross D

    2015-04-01

    For almost 50 years the structure of the Λ(1405) resonance has been a mystery. Even though it contains a heavy strange quark and has odd parity, its mass is lower than any other excited spin-1/2 baryon. Dalitz and co-workers speculated that it might be a molecular state of an antikaon bound to a nucleon. However, a standard quark-model structure is also admissible. Although the intervening years have seen considerable effort, there has been no convincing resolution. Here we present a new lattice QCD simulation showing that the strange magnetic form factor of the Λ(1405) vanishes, signaling the formation of an antikaon-nucleon molecule. Together with a Hamiltonian effective-field-theory model analysis of the lattice QCD energy levels, this strongly suggests that the structure is dominated by a bound antikaon-nucleon component. This result clarifies that not all states occurring in nature can be described within a simple quark model framework and points to the existence of exotic molecular meson-nucleon bound states. PMID:25884122

  4. Development of a liquid 3He target for experimental studies of antikaon-nucleon interaction at J-PARC

    NASA Astrophysics Data System (ADS)

    Iio, M.; Ishimoto, S.; Sato, M.; Enomoto, S.; Hashimoto, T.; Suzuki, S.; Iwasaki, M.; Hayano, R. S.

    2012-09-01

    A liquid 3He target system was developed for experimental studies of kaonic atoms and kaonic nuclei at J-PARC. 3He gas is liquefied in a heat exchanger cooled below 3.2 K by decompression of liquid 4He. To maintain a large acceptance of the cylindrical detector system for decay particles of kaonic nuclei, efficient heat transport between the separate target cell and the main unit is realized using circulation of liquid 3He. To minimize the amount of material, a vacuum vessel containing a carbon fiber reinforced plastic cylinder having an inside diameter of 150 mm and a thickness of 1 mm was produced. A target cell made of pure beryllium and beryllium-aluminum alloy was developed not only to minimize the amount of material but also to obtain high X-ray transmission. During a cooling test, the target cell was kept at 1.3 K at a pressure of 33 mbar. The total estimated heat load to the components including the target cell and heat exchanger cooled by liquid 4He decompression, was 0.21 W, and the liquid 4He consumption rate was 50 L/day.

  5. Fluid channeling system

    NASA Technical Reports Server (NTRS)

    Davis, Donald Y. (Inventor); Hitch, Bradley D. (Inventor)

    1994-01-01

    A fluid channeling system includes a fluid ejector, a heat exchanger, and a fluid pump disposed in series flow communication The ejector includes a primary inlet for receiving a primary fluid, and a secondary inlet for receiving a secondary fluid which is mixed with the primary fluid and discharged therefrom as ejector discharge. Heat is removed from the ejector discharge in the heat exchanger, and the heat exchanger discharge is compressed in the fluid pump and channeled to the ejector secondary inlet as the secondary fluid In an exemplary embodiment, the temperature of the primary fluid is greater than the maximum operating temperature of a fluid motor powering the fluid pump using a portion of the ejector discharge, with the secondary fluid being mixed with the primary fluid so that the ejector discharge temperature is equal to about the maximum operating temperature of the fluid motor.

  6. A three channel telemetry system

    NASA Technical Reports Server (NTRS)

    Lesho, Jeffery C.; Eaton, Harry A. C.

    1993-01-01

    A three channel telemetry system intended for biomedical applications is described. The transmitter is implemented in a single chip using a 2 micron BiCMOS processes. The operation of the system and the test results from the latest chip are discussed. One channel is always dedicated to temperature measurement while the other two channels are generic. The generic channels carry information from transducers that are interfaced to the system through on-chip general purpose operational amplifiers. The generic channels have different bandwidths: one from dc to 250 Hz and the other from dc to 1300 Hz. Each generic channel modulates a current controlled oscillator to produce a frequency modulated signal. The two frequency modulated signals are summed and used to amplitude modulate the temperature signal which acts as a carrier. A near-field inductive link telemeters the combined signals over a short distance. The chip operates on a supply voltage anywhere from 2.5 to 3.6 Volts and draws less than 1 mA when transmitting a signal. The chip can be incorporated into ingestible, implantable and other configurations. The device can free the patient from tethered data collection systems and reduces the possibility of infection from subcutaneous leads. Data telemetry can increase patient comfort leading to a greater acceptance of monitoring.

  7. Multiple channel data acquisition system

    DOEpatents

    Crawley, H. Bert; Rosenberg, Eli I.; Meyer, W. Thomas; Gorbics, Mark S.; Thomas, William D.; McKay, Roy L.; Homer, Jr., John F.

    1990-05-22

    A multiple channel data acquisition system for the transfer of large amounts of data from a multiplicity of data channels has a plurality of modules which operate in parallel to convert analog signals to digital data and transfer that data to a communications host via a FASTBUS. Each module has a plurality of submodules which include a front end buffer (FEB) connected to input circuitry having an analog to digital converter with cache memory for each of a plurality of channels. The submodules are interfaced with the FASTBUS via a FASTBUS coupler which controls a module bus and a module memory. The system is triggered to effect rapid parallel data samplings which are stored to the cache memories. The cache memories are uploaded to the FEBs during which zero suppression occurs. The data in the FEBs is reformatted and compressed by a local processor during transfer to the module memory. The FASTBUS coupler is used by the communications host to upload the compressed and formatted data from the module memory. The local processor executes programs which are downloaded to the module memory through the FASTBUS coupler.

  8. Multiple channel data acquisition system

    DOEpatents

    Crawley, H.B.; Rosenberg, E.I.; Meyer, W.T.; Gorbics, M.S.; Thomas, W.D.; McKay, R.L.; Homer, J.F. Jr.

    1990-05-22

    A multiple channel data acquisition system for the transfer of large amounts of data from a multiplicity of data channels has a plurality of modules which operate in parallel to convert analog signals to digital data and transfer that data to a communications host via a FASTBUS. Each module has a plurality of submodules which include a front end buffer (FEB) connected to input circuitry having an analog to digital converter with cache memory for each of a plurality of channels. The submodules are interfaced with the FASTBUS via a FASTBUS coupler which controls a module bus and a module memory. The system is triggered to effect rapid parallel data samplings which are stored to the cache memories. The cache memories are uploaded to the FEBs during which zero suppression occurs. The data in the FEBs is reformatted and compressed by a local processor during transfer to the module memory. The FASTBUS coupler is used by the communications host to upload the compressed and formatted data from the module memory. The local processor executes programs which are downloaded to the module memory through the FASTBUS coupler. 25 figs.

  9. KATP Channels in the Cardiovascular System.

    PubMed

    Foster, Monique N; Coetzee, William A

    2016-01-01

    KATP channels are integral to the functions of many cells and tissues. The use of electrophysiological methods has allowed for a detailed characterization of KATP channels in terms of their biophysical properties, nucleotide sensitivities, and modification by pharmacological compounds. However, even though they were first described almost 25 years ago (Noma 1983, Trube and Hescheler 1984), the physiological and pathophysiological roles of these channels, and their regulation by complex biological systems, are only now emerging for many tissues. Even in tissues where their roles have been best defined, there are still many unanswered questions. This review aims to summarize the properties, molecular composition, and pharmacology of KATP channels in various cardiovascular components (atria, specialized conduction system, ventricles, smooth muscle, endothelium, and mitochondria). We will summarize the lessons learned from available genetic mouse models and address the known roles of KATP channels in cardiovascular pathologies and how genetic variation in KATP channel genes contribute to human disease. PMID:26660852

  10. Microprocessor based 32 channel PCM telemetry system

    NASA Astrophysics Data System (ADS)

    Murthy, N. N.

    1987-08-01

    The details of a 32 channel PCM telemetry system developed to acquire data from flight experiments conducted on Pushpak aircraft and to be conducted on LCRA aircraft are presented. The system is designed using Intel 8085A central processing unit with its associated peripherals like 8255, 8251 and 8155. The system can be programmed to handle up to 32 channels of analog data. The bit rate can also be varied up to 56 Kilobits/sec.

  11. A multi-channel waveform digitizer system

    SciTech Connect

    Bieser, F.; Muller, W.F.J. )

    1990-04-01

    The authors report on the design and performance of a multichannel waveform digitizer system for use with the Multiple Sample Ionization Chamber (MUSIC) Detector at the Bevalac. 128 channels of 20 MHz Flash ADC plus 256 word deep memory are housed in a single crate. Digital thresholds and hit pattern logic facilitate zero suppression during readout which is performed over a standard VME bus.

  12. Fading channel issues in system engineering

    NASA Astrophysics Data System (ADS)

    Stein, Seymour

    1987-02-01

    The character of multipath-induced propagational fading is reviewed, along with the interpretations underlying use of the Rayleigh fading model to describe the process statistics. The relationship between this model and contemporary laboratory fading simulators is also outlined. The effects of the fading upon data communications are described, along with the techniques of modulation, diversity, coding, and adaptive equalization used in modern modem designs for operation over such channels. Finally, the system engineering problems are discussed of attempting to provide quantitative estimates of long-term link or network performance that takes into account the longer term channel variabilities.

  13. [Synopsis about the hypothesis of "information channel" of channel-collateral system].

    PubMed

    Chang, Xi-Lang

    2008-10-01

    The author of the present paper founded a theorem about the "incompleteness of single channel structure" (nerve, blood vessel, lymphatic, interspace, aperture, etc.) through quantitative and qualitative analysis about the economic information channel in the human body, which eliminates the probability of single channel structure in the information channel of channel (meridian)-collateral system. After comprehensive analysis on the current researches, the author puts forward a neodoxy, i.e., the body "information channel" structure of the channel-collateral system, mainly follows the distribution regularity of systemic statistics, and is not a single specific entity; various layers of the information channel in the main stems of the channel-collaterals are composed of optimized structure tissues. Hence, the structure of this information channel of channel-collateral system is an overall-optimized, sequential and compatible systemic structure. From this neodoxy, the author brings forward a working principle of channel-collaterals, which is supported theoretically by bio-auxology. The longitudinal distribution of the main stems of meridian-collaterals is considered to result from that in the process of the animal evolution, in the animals moving forward, the microscopic complicated movement of intracorporeal information and energy molecules is related to the forward macroscopic and non-uniform movement of organism in trans-measure. Its impulse and kinetic momentum forms a main vector in the longitudinal direction of the body (the direction of the main stem of channel-collaterals). In order to adapt to and utilize natural regularities, the main stems of the channel-collaterals gradually differentiate and evolve in the living organism, forming a whole system. The "hypothesis of biological origin of channel-collateral system" and "that of information channel of the channel-collaterals in the body" constitute a relatively complete theoretical system framework. PMID

  14. Single-channel prototype terahertz endoscopic system

    NASA Astrophysics Data System (ADS)

    Doradla, Pallavi; Alavi, Karim; Joseph, Cecil; Giles, Robert

    2014-08-01

    We demonstrate the design and development of an innovative single-channel terahertz (THz) prototype endoscopic imaging system based on flexible metal-coated THz waveguides and a polarization specific detection technique. The continuous-wave (CW) THz imaging system utilizes a single channel to transmit and collect the reflected intrinsic THz signal from the sample. Since the prototype system relies on a flexible waveguide assembly that is small enough in diameter, it can be readily integrated with a conventional optical endoscope. This study aims to show the feasibility of waveguide enabled THz imaging. We image various objects in transmission and reflection modes. We also image normal and cancerous colonic tissues in reflectance mode using a polarization specific imaging technique. The resulting cross-polarized THz reflectance images showed contrast between normal and cancerous colonic tissues at 584 GHz. The level of contrast observed using endoscopic imaging correlates well with contrast levels observed in ex vivo THz reflectance studies of colon cancer. This indicates that the single-channel flexible waveguide-based THz endoscope presented here represents a significant step forward in clinical endoscopic application of THz technology to aid in in vivo cancer screening.

  15. Multi-channel medical imaging system

    DOEpatents

    Frangioni, John V.

    2016-05-03

    A medical imaging system provides simultaneous rendering of visible light and fluorescent images. The system may employ dyes in a small-molecule form that remain in a subject's blood stream for several minutes, allowing real-time imaging of the subject's circulatory system superimposed upon a conventional, visible light image of the subject. The system may provide an excitation light source to excite the fluorescent substance and a visible light source for general illumination within the same optical guide used to capture images. The system may be configured for use in open surgical procedures by providing an operating area that is closed to ambient light. The systems described herein provide two or more diagnostic imaging channels for capture of multiple, concurrent diagnostic images and may be used where a visible light image may be usefully supplemented by two or more images that are independently marked for functional interest.

  16. Multi-channel medical imaging system

    DOEpatents

    Frangioni, John V

    2013-12-31

    A medical imaging system provides simultaneous rendering of visible light and fluorescent images. The system may employ dyes in a small-molecule form that remain in the subject's blood stream for several minutes, allowing real-time imaging of the subject's circulatory system superimposed upon a conventional, visible light image of the subject. The system may provide an excitation light source to excite the fluorescent substance and a visible light source for general illumination within the same optical guide used to capture images. The system may be configured for use in open surgical procedures by providing an operating area that is closed to ambient light. The systems described herein provide two or more diagnostic imaging channels for capture of multiple, concurrent diagnostic images and may be used where a visible light image may be usefully supplemented by two or more images that are independently marked for functional interest.

  17. 47 CFR 22.1007 - Channels for offshore radiotelephone systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Channels for offshore radiotelephone systems. 22.1007 Section 22.1007 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Offshore Radiotelephone Service § 22.1007 Channels for offshore radiotelephone systems. The channels listed in...

  18. 16. VIEW NORTH FROM SWINGSPAN DECK, CHANNEL OPEN, FENDER SYSTEM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. VIEW NORTH FROM SWING-SPAN DECK, CHANNEL OPEN, FENDER SYSTEM AND ABUTMENT ON CHANNEL END OF NORTHERN FIXED SPAN; new bridge located on right - Tipers Bridge, Spanning Great Wicomico River at State Route 200, Kilmarnock, Lancaster County, VA

  19. The Discovery Channel Telescope optical coating system

    NASA Astrophysics Data System (ADS)

    Marshall, Heather K.; Ash, Gary S.; Parsley, William F.

    2010-07-01

    The Discovery Channel Telescope (DCT) is a project of Lowell Observatory, undertaken with support from Discovery Communications, Inc., to design and construct a 4-meter class telescope and support facility on a site approximately 40 miles southeast of Flagstaff, AZ. Lowell Observatory contracted with Dynavac of Hingham, MA to design and build an optical coating system for the DCT optics. The DCT Optical Coating System includes a mechanical roughing pump, two high-vacuum cryogenic pumps, a Meissner trap, evaporative filament aluminum deposition system, LabView software and PLC-based control system, and all ancillary support equipment. The system was installed at the site and acceptance testing was completed in October 2009. The Optical Coating System achieved near perfect reflectivity performance, thickness uniformity of 1000 angstroms +/-10%, and adhesion conforming to MIL-F-48616, Section 4.6.8.1. This paper discusses the design and analysis of the coating system, the process of transportation and assembly as well as testing results.

  20. Multiple channel optical data acquisition system

    DOEpatents

    Fasching, G.E.; Goff, D.R.

    1985-02-22

    A multiple channel optical data acquisition system is provided in which a plurality of remote sensors monitoring specific process variable are interrogated by means of a single optical fiber connecting the remote station/sensors to a base station. The remote station/sensors derive all power from light transmitted through the fiber from the base station. Each station/sensor is individually accessed by means of a light modulated address code sent over the fiber. The remote station/sensors use a single light emitting diode to both send and receive light signals to communicate with the base station and provide power for the remote station. The system described can power at least 100 remote station/sensors over an optical fiber one mile in length.

  1. Channel coding in the space station data system network

    NASA Technical Reports Server (NTRS)

    Healy, T.

    1982-01-01

    A detailed discussion of the use of channel coding for error correction, privacy/secrecy, channel separation, and synchronization is presented. Channel coding, in one form or another, is an established and common element in data systems. No analysis and design of a major new system would fail to consider ways in which channel coding could make the system more effective. The presence of channel coding on TDRS, Shuttle, the Advanced Communication Technology Satellite Program system, the JSC-proposed Space Operations Center, and the proposed 30/20 GHz Satellite Communication System strongly support the requirement for the utilization of coding for the communications channel. The designers of the space station data system have to consider the use of channel coding.

  2. Oxidation of ion channels in the aging nervous system.

    PubMed

    Patel, Rahul; Sesti, Federico

    2016-05-15

    Ion channels are integral membrane proteins that allow passive diffusion of ions across membranes. In neurons and in other excitable cells, the harmonious coordination between the numerous types of ion channels shape and propagate electrical signals. Increased accumulation of reactive oxidative species (ROS), and subsequent oxidation of proteins, including ion channels, is a hallmark feature of aging and may contribute to cell failure as a result. In this review we discuss the effects of ROS on three major types of ion channels of the central nervous system, namely the potassium (K(+)), calcium (Ca(2+)) and sodium (Na(+)) channels. We examine two general mechanisms through which ROS affect ion channels: via direct oxidation of specific residues and via indirect interference of pathways that regulate the channels. The overall status of the present studies indicates that the interaction of ion channels with ROS is multimodal and pervasive in the central nervous system and likely constitutes a general mechanism of aging susceptibility. PMID:26947620

  3. Calibration of Micro Channel Plate Detector Systems

    NASA Astrophysics Data System (ADS)

    Dekat, S.; Kypreos, T.; Moore, J.; Gay, D.; Wiedenhoever, I.

    2004-10-01

    Two position-sensitive micro-channel plate (MCP) detector systems have been assembled and tested at the University of North Florida. These detectors track heavy-ions in Florida State University's radioactive beam facility, RESOLUT. Plans for the systems were supplied by C. J. Gross and D. Shapira of ORNL. Each system consists of an aluminized 0.9-micron Mylar foil facing a 40-mm diameter MCP sensor head with a resistive anode encoder (RAE). Delta electrons emitted as a heavy ion passes through the foil are accelerated toward the sensor head by an electric field. The divergence of the electrons is limited by a magnetic field from a NdFeB magnet which is coaxial with and behind the sensor head. A digital oscilloscope has been programmed to convert amplified and shaped pulses from the RAE into position coordinates. Calibration experiments were performed with the foil replaced by an aluminum grid of 1 mm wide strips. Using alpha particles from a ^241Am source incident on the grid, optimum operating parameters were established by resolving aluminum strips separated by 1 mm.

  4. From natural to bioassisted and biomimetic artificial water channel systems.

    PubMed

    Barboiu, Mihail; Gilles, Arnaud

    2013-12-17

    Within biological systems, natural channels and pores transport metabolites across the cell membranes. Researchers have explored artificial ion-channel architectures as potential mimics of natural ionic conduction. All these synthetic systems have produced an impressive collection of alternative artificial ion-channels. Amazingly, researchers have made far less progress in the area of synthetic water channels. The development of synthetic biomimetic water channels and pores could contribute to a better understanding of the natural function of protein channels and could offer new strategies to generate highly selective, advanced water purification systems. Despite the imaginative work by synthetic chemists to produce sophisticated architectures that confine water clusters, most synthetic water channels have used natural proteins channels as the selectivity components, embedded in the diverse arrays of bioassisted artificial systems. These systems combine natural proteins that present high water conductance states under natural conditions with artificial lipidic or polymeric matrixes. Experimental results have demonstrated that natural biomolecules can be used as bioassisted building blocks for the construction of highly selective water transport through artificial membranes. A next step to further the potential of these systems was the design and construction of simpler compounds that maintain the high conduction activity obtained with natural compounds leading to fully synthetic artificial biomimetic systems. Such studies aim to use constitutional selective artificial superstructures for water/proton transport to select functions similar to the natural structures. Moving to simpler water channel systems offers a chance to better understand mechanistic and structural behaviors and to uncover novel interactive water-channels that might parallel those in biomolecular systems. This Account discusses the incipient development of the first artificial water channels

  5. Channel capacities of an exactly solvable spin-star system

    NASA Astrophysics Data System (ADS)

    Arshed, Nigum; Toor, A. H.; Lidar, Daniel A.

    2010-06-01

    We calculate the entanglement-assisted and -unassisted channel capacities of an exactly solvable spin star system, which models the quantum dephasing channel. The capacities for this non-Markovian model exhibit a strong dependence on the coupling strengths of the bath spins with the system, the bath temperature, and the number of bath spins. For equal couplings and bath frequencies, the channel becomes periodically noiseless.

  6. Channel capacities of an exactly solvable spin-star system

    SciTech Connect

    Arshed, Nigum; Toor, A. H.; Lidar, Daniel A.

    2010-06-15

    We calculate the entanglement-assisted and -unassisted channel capacities of an exactly solvable spin star system, which models the quantum dephasing channel. The capacities for this non-Markovian model exhibit a strong dependence on the coupling strengths of the bath spins with the system, the bath temperature, and the number of bath spins. For equal couplings and bath frequencies, the channel becomes periodically noiseless.

  7. Role of TRP channels in the cardiovascular system

    PubMed Central

    Yue, Zhichao; Xie, Jia; Yu, Albert S.; Stock, Jonathan; Du, Jianyang

    2014-01-01

    The transient receptor potential (TRP) superfamily consists of a large number of nonselective cation channels with variable degree of Ca2+-permeability. The 28 mammalian TRP channel proteins can be grouped into six subfamilies: canonical, vanilloid, melastatin, ankyrin, polycystic, and mucolipin TRPs. The majority of these TRP channels are expressed in different cell types including both excitable and nonexcitable cells of the cardiovascular system. Unlike voltage-gated ion channels, TRP channels do not have a typical voltage sensor, but instead can sense a variety of other stimuli including pressure, shear stress, mechanical stretch, oxidative stress, lipid environment alterations, hypertrophic signals, and inflammation products. By integrating multiple stimuli and transducing their activity to downstream cellular signal pathways via Ca2+ entry and/or membrane depolarization, TRP channels play an essential role in regulating fundamental cell functions such as contraction, relaxation, proliferation, differentiation, and cell death. With the use of targeted deletion and transgenic mouse models, recent studies have revealed that TRP channels are involved in numerous cellular functions and play an important role in the pathophysiology of many diseases in the cardiovascular system. Moreover, several TRP channels are involved in inherited diseases of the cardiovascular system. This review presents an overview of current knowledge concerning the physiological functions of TRP channels in the cardiovascular system and their contributions to cardiovascular diseases. Ultimately, TRP channels may become potential therapeutic targets for cardiovascular diseases. PMID:25416190

  8. Ion Channels as Drug Targets in Central Nervous System Disorders

    PubMed Central

    Waszkielewicz, A.M; Gunia, A; Szkaradek, N; Słoczyńska, K; Krupińska, S; Marona, H

    2013-01-01

    Ion channel targeted drugs have always been related with either the central nervous system (CNS), the peripheral nervous system, or the cardiovascular system. Within the CNS, basic indications of drugs are: sleep disorders, anxiety, epilepsy, pain, etc. However, traditional channel blockers have multiple adverse events, mainly due to low specificity of mechanism of action. Lately, novel ion channel subtypes have been discovered, which gives premises to drug discovery process led towards specific channel subtypes. An example is Na+ channels, whose subtypes 1.3 and 1.7-1.9 are responsible for pain, and 1.1 and 1.2 – for epilepsy. Moreover, new drug candidates have been recognized. This review is focusing on ion channels subtypes, which play a significant role in current drug discovery and development process. The knowledge on channel subtypes has developed rapidly, giving new nomenclatures of ion channels. For example, Ca2+ channels are not any more divided to T, L, N, P/Q, and R, but they are described as Cav1.1-Cav3.3, with even newer nomenclature α1A-α1I and α1S. Moreover, new channels such as P2X1-P2X7, as well as TRPA1-TRPV1 have been discovered, giving premises for new types of analgesic drugs. PMID:23409712

  9. Channel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03693 Channel

    This channel is located south of Iani Chaos.

    Image information: VIS instrument. Latitude -10.9N, Longitude 345.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  10. The new secondary channel control system at TRIUMF

    NASA Astrophysics Data System (ADS)

    Keitel, R.; Bishop, D.; Dale, D.; England, N.; Harrison, D.

    1990-08-01

    The control of the secondary channels at TRIUMF has been decentralized. Each channel is now controlled through a single CAMAC crate from an IBM PC in the experimental counting room. Intelligent motor controllers were developed to replace the ageing slit control system. Advanced features of the control software package TICS, such as computer optimization of channel parameters and high-voltage conditioning of the de separators, are described.

  11. Energy, time, and channel evolution in catastrophically disturbed fluvial systems

    USGS Publications Warehouse

    Simon, A.

    1992-01-01

    Specific energy is shown to decrease nonlinearly with time during channel evolution and provides a measure of reductions in available energy at the channel bed. Data from two sites show convergence towards a minimum specific energy with time. Time-dependent reductions in specific energy at a point act in concert with minimization of the rate of energy dissipation over a reach during channel evolution as the fluvial systems adjust to a new equilibrium.

  12. Ion Channel Expression in the Developing Enteric Nervous System

    PubMed Central

    Stamp, Lincon A.; Fegan, Emily; Dent, Stephan; Cooper, Edward C.; Lomax, Alan E.; Anderson, Colin R.; Bornstein, Joel C.; Young, Heather M.; McKeown, Sonja J.

    2015-01-01

    The enteric nervous system arises from neural crest-derived cells (ENCCs) that migrate caudally along the embryonic gut. The expression of ion channels by ENCCs in embryonic mice was investigated using a PCR-based array, RT-PCR and immunohistochemistry. Many ion channels, including chloride, calcium, potassium and sodium channels were already expressed by ENCCs at E11.5. There was an increase in the expression of numerous ion channel genes between E11.5 and E14.5, which coincides with ENCC migration and the first extension of neurites by enteric neurons. Previous studies have shown that a variety of ion channels regulates neurite extension and migration of many cell types. Pharmacological inhibition of a range of chloride or calcium channels had no effect on ENCC migration in cultured explants or neuritogenesis in vitro. The non-selective potassium channel inhibitors, TEA and 4-AP, retarded ENCC migration and neuritogenesis, but only at concentrations that also resulted in cell death. In summary, a large range of ion channels is expressed while ENCCs are colonizing the gut, but we found no evidence that ENCC migration or neuritogenesis requires chloride, calcium or potassium channel activity. Many of the ion channels are likely to be involved in the development of electrical excitability of enteric neurons. PMID:25798587

  13. 47 CFR 22.1007 - Channels for offshore radiotelephone systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Channels for offshore radiotelephone systems. 22.1007 Section 22.1007 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Offshore Radiotelephone Service § 22.1007 Channels for...

  14. Design and performance of the LANL 158-channel magnetoencephalography system

    SciTech Connect

    Matlachov, A. N.; Kraus, Robert H., Jr.; Espy, M. A.; Best, E. D.; Briles, M. Carolyn; Raby, E. Y.; Flynn, E. R.

    2002-01-01

    Design and performance for a recently completed whole-head magnetoencephalography (MEG) system using a superconducting imaging-surface (SIS) surrounding an array of SQUID magnetometers is reported. The helmet-like SIS is hemispherical in shape with a brim. The SIS images nearby sources while shields sensors from ambient magnetic noise. The shielding factor depends on magnetometer position and orientation. Typical shielding values of 200 in central sulcus area have been observed. Nine reference channels form three vector magnetometers, which are placed outside SIS. Signal channels consist of 149 SQUID magnetometers with 0.84nT/{Phi}{sub 0} field sensitivity and less then 3 fT/{radical}Hz noise. Typical SQUID - room temperature separations are about 20mm in the cooled state. Twelve 16-channel flux-lock loop units are connected to two 96-channel control units allowing up to 192 total SQUID channels. The control unit includes signal conditioning circuits as well as system test and control circuits. After conditioning all signals are fed to 192-channel, 24-bit data acquisition system capable of sampling up to 48kSa/sec/channel. The SIS-MEG system enables high-quality human functional brain data to be recorded in a one-layer magnetically shielded room.

  15. Note: Optical receiver system for 152-channel magnetoencephalography

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Mok; Kwon, Hyukchan; Yu, Kwon-kyu; Lee, Yong-Ho; Kim, Kiwoong

    2014-11-01

    An optical receiver system composing 13 serial data restore/synchronizer modules and a single module combiner converted optical 32-bit serial data into 32-bit synchronous parallel data for a computer to acquire 152-channel magnetoencephalography (MEG) signals. A serial data restore/synchronizer module identified 32-bit channel-voltage bits from 48-bit streaming serial data, and then consecutively reproduced 13 times of 32-bit serial data, acting in a synchronous clock. After selecting a single among 13 reproduced data in each module, a module combiner converted it into 32-bit parallel data, which were carried to 32-port digital input board in a computer. When the receiver system together with optical transmitters were applied to 152-channel superconducting quantum interference device sensors, this MEG system maintained a field noise level of 3 fT/√Hz @ 100 Hz at a sample rate of 1 kSample/s per channel.

  16. Note: Optical receiver system for 152-channel magnetoencephalography

    SciTech Connect

    Kim, Jin-Mok; Kwon, Hyukchan; Yu, Kwon-kyu; Lee, Yong-Ho; Kim, Kiwoong

    2014-11-15

    An optical receiver system composing 13 serial data restore/synchronizer modules and a single module combiner converted optical 32-bit serial data into 32-bit synchronous parallel data for a computer to acquire 152-channel magnetoencephalography (MEG) signals. A serial data restore/synchronizer module identified 32-bit channel-voltage bits from 48-bit streaming serial data, and then consecutively reproduced 13 times of 32-bit serial data, acting in a synchronous clock. After selecting a single among 13 reproduced data in each module, a module combiner converted it into 32-bit parallel data, which were carried to 32-port digital input board in a computer. When the receiver system together with optical transmitters were applied to 152-channel superconducting quantum interference device sensors, this MEG system maintained a field noise level of 3 fT/√Hz @ 100 Hz at a sample rate of 1 kSample/s per channel.

  17. KCNQ potassium channels in sensory system and neural circuits

    PubMed Central

    Wang, Jing-jing; Li, Yang

    2016-01-01

    M channels, an important regulator of neural excitability, are composed of four subunits of the Kv7 (KCNQ) K+ channel family. M channels were named as such because their activity was suppressed by stimulation of muscarinic acetylcholine receptors. These channels are of particular interest because they are activated at the subthreshold membrane potentials. Furthermore, neural KCNQ channels are drug targets for the treatments of epilepsy and a variety of neurological disorders, including chronic and neuropathic pain, deafness, and mental illness. This review will update readers on the roles of KCNQ channels in the sensory system and neural circuits as well as discuss their respective mechanisms and the implications for physiology and medicine. We will also consider future perspectives and the development of additional pharmacological models, such as seizure, stroke, pain and mental illness, which work in combination with drug-design targeting of KCNQ channels. These models will hopefully deepen our understanding of KCNQ channels and provide general therapeutic prospects of related channelopathies. PMID:26687932

  18. Multiple-channel Streaming Delivery for Omnidirectional Vision System

    NASA Astrophysics Data System (ADS)

    Iwai, Yoshio; Nagahara, Hajime; Yachida, Masahiko

    An omnidirectional vision is an imaging system that can capture a surrounding image in whole direction by using a hyperbolic mirror and a conventional CCD camera. This paper proposes a streaming server that can efficiently transfer movies captured by an omnidirectional vision system through the Internet. The proposed system uses multiple channels to deliver multiple movies synchronously. Through this method, the system enables clients to view the different direction of omnidirectional movies and also support the function to change the view are during playback period. Our evaluation experiments show that our proposed streaming server can effectively deliver multiple movies via multiple channels.

  19. Pre-experiment testing of the Multi Channel Systems 16-channel preamplifier CPA16

    SciTech Connect

    Patin, J B; Stoyer, M A; Moody, K J; Friensehner, A V

    2003-11-03

    The 16-channel preamplifier model CPA16 from Multi Channel Systems was studied. The CPA16 preamplifier/amplifier module is a candidate to be used as the preamplifiers and amplifiers for the focal plane detectors of the Mass Analyzer of Super Heavy Atoms (MASHA). The equipment used to test the CPA16, the results of testing the CPA16 with a pulser, a mixed {sup 229}Th/{sup 148}Gd source and a {sup 252}Cf source, and a summary of the results will be presented.

  20. Robust Read Channel System Directly Processing Asynchronous Sampling Data

    NASA Astrophysics Data System (ADS)

    Yamamoto, Akira; Mouri, Hiroki; Yamamoto, Takashi

    2006-02-01

    In this study, we describe a robust read channel employing a novel timing recovery system and a unique Viterbi detector which extracts channel timing and channel data directly from asynchronous sampling data. The timing recovery system in the proposed read channel has feed-forward architecture and consists entirely of digital circuits. Thus, it enables robust timing recovery at high-speed and has no performance deterioration caused by variations in analog circuits. The Viterbi detector not only detects maximum-likelihood data using a reference level generator, but also transforms asynchronous data into pseudosynchronous data using two clocks, such as an asynchronous clock generated by a frequency synthesizer and a pseudosynchronous clock generated by a timing detector. The proposed read channel has achieved a constant and fast frequency acquisition time against initial frequency error and has improved its bit error rate performance. This robust read channel system can be used for high-speed signal processing and LSIs using nanometer-scale semiconductor processes.

  1. Rearing channel catfish in a bioflac production system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Production of channel catfish in an intensively managed mixed suspended-growth, or biofloc, production system was investigated in two studies. Management of unassimilated feed nitrogen is important as feeding rate is increased in intensified production systems. In a mixed suspended-growth production...

  2. Channel simulation for direct-detection optical communication systems

    NASA Technical Reports Server (NTRS)

    Tycz, M.; Fitzmaurice, M. W.

    1974-01-01

    A technique is described for simulating the random modulation imposed by atmospheric scintillation and transmitter pointing jitter on a direct-detection optical communication system. The system is capable of providing signal fading statistics which obey log-normal, beta, Rayleigh, Ricean, or chi-square density functions. Experimental tests of the performance of the channel simulator are presented.

  3. Channel simulation for direct detection optical communication systems

    NASA Technical Reports Server (NTRS)

    Tycz, M.; Fitzmaurice, M. W.

    1974-01-01

    A technique is described for simulating the random modulation imposed by atmospheric scintillation and transmitter pointing jitter on a direct detection optical communication system. The system is capable of providing signal fading statistics which obey log normal, beta, Rayleigh, Ricean or chi-squared density functions. Experimental tests of the performance of the Channel Simulator are presented.

  4. A Fully Implantable 96-channel Neural Data Acquisition System

    PubMed Central

    Rizk, Michael; Bossetti, Chad A; Jochum, Thomas A; Callender, Stephen H; Nicolelis, Miguel A L; Turner, Dennis A; Wolf, Patrick D

    2009-01-01

    A fully implantable neural data acquisition system is a key component of a clinically viable brain-machine interface. This type of system must communicate with the outside world and obtain power without the use of wires that cross through the skin. We present a 96-channel fully implantable neural data acquisition system. This system performs spike detection and extraction within the body and wirelessly transmits data to an external unit. Power is supplied wirelessly through the use of inductively-coupled coils. The system was implanted acutely in sheep and successfully recorded, processed, and transmitted neural data. Bidirectional communication between the implanted system and an external unit was successful over a range of 2 m. The system is also shown to integrate well into a brain-machine interface. This demonstration of a high channel-count fully implanted neural data acquisition system is a critical step in the development of a clinically viable brain-machine interface. PMID:19255459

  5. Ultrasound Tested in Channel Catfish Production Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Data are provided demonstrating application of ultrasound technologies for enhancing water quality in aquaculture systems, including the potential use in hatchery and grow-out ponds. Experiments included demonstration of no-impact on fish growth, reduction of bacterial biomass in tank studies by 60...

  6. Wave-current interaction in evolution of rip channel system

    NASA Astrophysics Data System (ADS)

    Uchiyama, Y.; Miyazaki, D.; Kaida, H.

    2014-12-01

    Current effects on waves (CEW) have been recognized to play an essential role in attenuating offshore extent of rip currents (e.g., Haas et al., 1999; Yu and Slinn, 2003; Weir et al., 2011). This mechanism is presumed to be responsible for morphological processes of sandy beaches. The present study aims at analyzing influence of CEW on the evolution of rip channel system due to deformation of an alongshore-uniform barred topography. We exploit a phase-averaged barotropic numerical model based on ROMS with an Eulerian-averaged vortex force formalism (McWilliams et al., 2004) coupled with a refraction wave model (ROMS-WEC; Uchiyama et al., 2009; 2010). An empirical total sediment load model of Soulsby and Van Rijn (1997) with a diffusive downslope transport effect (e.g., Garnier et al., 2008) is implemented for evaluating sediment transport and associated morphological evolution. The coupled, wave-current-sediment model successfully reproduces development of the alongshore periodic rip channel topography with normal incident offshore waves. The initial alongshore-uniform barred topography evolves into a rhythmic rip channel system through intrinsic instability triggered by a small disturbance. We then exhibit the rip current reduction by CEW on an immobile single barred beach with equally spaced rip channels. Among the other CEW such as the Doppler shift and wave set-down/up, wave refraction on currents is found to be most important in modifying the wavenumber field and breaker dissipation, leading to a systematic modulation in the diagnostic momentum balance. We further demonstrate that CEW has the first-order effect on the morphological processes where the resultant rip channel spacing is elongated 25-50% as compared to the case without CEW. In particular, CEW is crucial in widening the rip channel spacing, shoaling the rip channel in the surfzone, and shrinking submerged crescent mounds in the offshore beneath rip heads.

  7. Channel Extension in Deep-Water Distributive Systems

    NASA Astrophysics Data System (ADS)

    Hoyal, D. C.; Sheets, B. A.

    2007-12-01

    acceleration to Fr'-critical conditions and the formation of a depositional hydraulic jump, which perturbs sediment transport and ends channel extension. Similar morphodynamic length scale controls are observed in shallow water fan-delta experiments (e.g., SAFL DB-03) and in 2-D depositional cyclic steps. The experiments seem to explain two interesting observations from the earlier self-organized fan experiments and from real submarine fans. Firstly, the observation of 'perched' fills at the steep entrances to salt withdrawal minibasins (e.g., in the Gulf of Mexico) suggesting higher sedimentation rates (or inefficient sediment transport) on higher slopes (initially higher than at the slope break downstream). Secondly, strong progradation as the fan evolves and slope decreases in 'perched' fans suggests increasing flow efficiency on lower slopes, at least over a certain window of parameter space. Apparently deep water systems have a tendency to self-regulate even when flows differ significantly in initial density. The observed modulation to Fr'-critical flow appears to be an important control on length scales in deep- water distributive channel systems, potentially explaining strong deepwater progradation or 'delta-like' patterns that have remained paradoxical. Near critical conditions have been inferred from observations of many active submarine fans but the extent to which these results from conservative density currents apply to non-conservative and potentially 'ignitive' turbidity currents is the subject of ongoing investigation.

  8. Embedded system of image storage based on fiber channel

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Su, Wanxin; Xing, Zhongbao; Wang, Hualong

    2008-03-01

    In domains of aerospace, aviation, aiming, and optic measure etc., the embedded system of imaging, processing and recording is absolutely necessary, which has small volume, high processing speed and high resolution. But the embedded storage technology becomes system bottleneck because of developing slowly. It is used to use RAID to promote storage speed, but it is unsuitable for the embedded system because of its big volume. Fiber channel (FC) technology offers a new method to develop the high-speed, portable storage system. In order to make storage subsystem meet the needs of high storage rate, make use of powerful Virtex-4 FPGA and high speed fiber channel, advance a project of embedded system of digital image storage based on Xilinx Fiber Channel Arbitrated Loop LogiCORE. This project utilizes Virtex- 4 RocketIO MGT transceivers to transmit the data serially, and connects many Fiber Channel hard drivers by using of Arbitrated Loop optionally. It can achieve 400MBps storage rate, breaks through the bottleneck of PCI interface, and has excellences of high-speed, real-time, portable and massive capacity.

  9. Visualization of an entangled channel spin-1 system

    SciTech Connect

    Sirsi, Swarnamala; Adiga, Veena

    2010-08-15

    Covariance matrix formalism gives powerful entanglement criteria for continuous as well as finite dimensional systems. We use this formalism to study a mixed channel spin-1 system which is well known in nuclear reactions. A spin-j state can be visualized as being made up of 2j spinors which are represented by a constellation of 2j points on a Bloch sphere using Majorana construction. We extend this formalism to visualize an entangled mixed spin-1 system.

  10. Integrated source and channel encoded digital communication system design study

    NASA Technical Reports Server (NTRS)

    Huth, G. K.; Trumpis, B. D.; Udalov, S.

    1975-01-01

    Various aspects of space shuttle communication systems were studied. The following major areas were investigated: burst error correction for shuttle command channels; performance optimization and design considerations for Costas receivers with and without bandpass limiting; experimental techniques for measuring low level spectral components of microwave signals; and potential modulation and coding techniques for the Ku-band return link. Results are presented.

  11. Channel systems and lobe construction in the Mississippi Fan

    USGS Publications Warehouse

    Garrison, L. E.; Kenyon, Neil H.; Bouma, A.H.

    1982-01-01

    Morphological features on the Mississippi Fan in the eastern Gulf of Mexico were mapped using GLORIA II, a long-range side-scan sonar system. Prominent is a sinuous channel flanked by well-developed levees and occasional crevasse splays. The channel follows the axis and thickest part of the youngest fan lobe; seismic-reflection profiles offer evidence that its course has remained essentially constant throughout lobe development. Local modification and possible erosion of levees by currents indicates a present state of inactivity. Superficial sliding has affected part of the fan lobe, but does not appear to have been a factor in lobe construction. ?? 1982 A. M. Dowden, Inc.

  12. Integrated source and channel encoded digital communications system design study

    NASA Technical Reports Server (NTRS)

    Huth, G. K.

    1974-01-01

    Studies on the digital communication system for the direct communication links from ground to space shuttle and the links involving the Tracking and Data Relay Satellite (TDRS). Three main tasks were performed:(1) Channel encoding/decoding parameter optimization for forward and reverse TDRS links,(2)integration of command encoding/decoding and channel encoding/decoding; and (3) modulation coding interface study. The general communication environment is presented to provide the necessary background for the tasks and to provide an understanding of the implications of the results of the studies.

  13. Athabasca Valles, Mars: A lava-draped channel system

    USGS Publications Warehouse

    Jaeger, W.L.; Keszthelyi, L.P.; McEwen, A.S.; Dundas, C.M.; Russell, P.S.

    2007-01-01

    Athabasca Valles is a young outflow channel system on Mars that may have been carved by catastrophic water floods. However, images acquired by the High-Resolution Imaging Science Experiment camera onboard the Mars Reconnaissance Orbiter spacecraft reveal that Athabasca Valles is now entirely draped by a thin layer of solidified lava - the remnant of a once-swollen river of molten rock. The lava erupted from a fissure, inundated the channels, and drained downstream in geologically recent times. Purported ice features in Athabasca Valles and its distal basin, Cerberus Palus, are actually composed of this lava. Similar volcanic processes may have operated in other ostensibly fluvial channels, which could explain in part why the landers sent to investigate sites of ancient flooding on Mars have predominantly found lava at the surface instead.

  14. Redundant uplink optical channel for visible light communication systems

    NASA Astrophysics Data System (ADS)

    Vladescu, Marian; Vuza, Dan Tudor

    2015-02-01

    The increased interest in optical wireless (OW), as a complementary solution for radio frequency (RF) wireless technology, in conjunction with the significant deployments in LED lighting technology, led to the need to achieve lighting and wireless communication simultaneously in indoor environments. Visible light communication (VLC) technology provides an opportunity and infrastructure for the high-speed low-cost wireless communication. There are still open issues in VLC such as: uplink channel, LED modulation bandwidth, and LED nonlinearity. In this paper we addressed the uplink channel implementation, being a key issue in the OW communication system in order to allow full connectivity for a terminal (duplex transmission). VLC in full duplex mode requires the usage of a hybrid technology, such as infrared optical uplink, retro-reflecting transceivers, or even RF. The solution we proposed is to create a redundant optical uplink channel, using near ultraviolet (UV) and near infrared (IR) spectra.

  15. Photoionization of few electron systems: a hybrid coupled channels approach

    NASA Astrophysics Data System (ADS)

    Pramod Majety, Vinay; Zielinski, Alejandro; Scrinzi, Armin

    2015-06-01

    We present the hybrid anti-symmetrized coupled channels method for the calculation of fully differential photo-electron spectra of multi-electron atoms and small molecules interacting with strong laser fields. The method unites quantum chemical few-body electronic structure with strong-field dynamics by solving the time dependent Schrödinger equation in a fully anti-symmetrized basis composed of multi-electron states from quantum chemistry and a one-electron numerical basis. Photoelectron spectra are obtained via the time dependent surface flux (tSURFF) method. Performance and accuracy of the approach are demonstrated for spectra from the helium and beryllium atoms and the hydrogen molecule in linearly polarized laser fields at wavelengths from 21 to 400 nm. At long wavelengths, helium and the hydrogen molecule at equilibrium inter-nuclear distance can be approximated as single channel systems whereas beryllium needs a multi-channel description.

  16. Joint Channel Estimation and Signal Detection for the OFDM System Without Cyclic Prefix Over Doubly-Selective Channels

    NASA Astrophysics Data System (ADS)

    Song, Lijun; Lei, Xia; Jin, Maozhu; Lv, Zhihan

    2015-12-01

    In the high-speed railway wireless communication, a joint channel estimation and signal detection algorithm is proposed for the orthogonal frequency division multiplexing (OFDM) system without cyclic prefix in the doubly-selective fading channels. Our proposed method first combines the basis expansion model (BEM) and the inter symbol interference (ISI) cancellation to overcome the situation that exists with the fast time-varying channel and the normalized maximum multipath channel exceeding the length of the cyclic prefix (CP). At first, the channel estimation and signal detection can be approximated without considering the ISI. Then, the channel parameters and signal detection are updated through ISI cancellation and circular convolution reconstruction from the frequency domain. The simulations show the algorithm can improve the performance of channel estimation and signal detection.

  17. A 96-channel neural stimulation system for driving AIROF microelectrodes.

    PubMed

    Hu, Z; Troyk, P; Cogan, S

    2004-01-01

    We present the design and testing of a 96-channel stimulation system to drive activated iridium oxide (AIROF) microelectrodes within safe charge-injection limits. Our system improves upon the traditional capacitively coupled, symmetric charge-balanced biphasic stimulation waveform so as to maximize charge-injection capacity without endangering the microelectrodes. It can deliver computer-controlled cathodic current pulse for to up to 96 AIROF microelectrodes and positively bias them during the inter-pulse interval. The stimulation system is comprised of (1) 12 custom-designed PCB boards each hosting an 8-channel ASIC chip, (2) a motherboard to communicate between these 12 boards and the PC, (3) the PC interface equipped with a DIO card and the corresponding software. We plan to use this system in animal experiments for intracortical neural stimulation of implanted electrodes within our visual prosthesis project. PMID:17271241

  18. Correcting Aberrations in Complex Magnet Systems for Muon Cooling Channels

    SciTech Connect

    J.A. Maloney, B. Erdelyi, A. Afanaciev, R.P. Johnson, Y.S. Derbenev, V.S. Morozov

    2011-03-01

    Designing and simulating complex magnet systems needed for cooling channels in both neutrino factories and muon colliders requires innovative techniques to correct for both chromatic and spherical aberrations. Optimizing complex systems, such as helical magnets for example, is also difficult but essential. By using COSY INFINITY, a differential algebra based code, the transfer and aberration maps can be examined to discover what critical terms have the greatest influence on these aberrations.

  19. Adaptive Channel-Tracking Method and Equalization for MC-CDMA Systems over Rapidly Fading Channel under Colored Noise

    NASA Astrophysics Data System (ADS)

    Yang, Chang-Yi; Chen, Bor-Sen

    2010-12-01

    A recursive maximum-likelihood (RML) algorithm for channel estimation under rapidly fading channel and colored noise in a multicarrier code-division multiple-access (MC-CDMA) system is proposed in this paper. A moving-average model with exogenous input (MAX) is given to describe the transmission channel and colored noise. Based on the pseudoregression method, the proposed RML algorithm can simultaneously estimate the parameters of channel and colored noise. Following the estimation results, these parameters can be used to enhance the minimum mean-square error (MMSE) equalizer. Considering high-speed mobile stations, a one-step linear trend predictor is added to improve symbol detection. Simulation results indicate that the proposed RML estimator can track the channel more precisely than the conventional estimator. Meanwhile, the performance of the proposed enhanced MMSE equalizer is robust to the rapidly Rayleigh fading channel under colored noise in the MC-CDMA systems.

  20. Sample Analysis Code System for the Dual Channel Counter.

    Energy Science and Technology Software Center (ESTSC)

    1994-09-14

    Version 00 RADCOMPT automates gross alpha and gross beta sample analysis calculations and, in many cases, warns the technologist when a hazard level is being approached or when it has been exceeded. The RADCOMPT program is unique in that it corrects for crosstalk between channels, and in this way provides increased accuracy and efficiency. Even though it is designed explicitly for the analyses of air samples and wipe samples, it can also be used formore » other sample types. It is designed to be used with a dual channel counter (in which one channel is used for alpha detection and the other for beta detection), but may be used with two single channel counters employed for the same purpose. In addition, it provides an automated means for the execution of the following radiological sample analyses protocol: A. Calibration of the counting system B. Calculation of sample activity or air activity concentrations (with the activities of air activity concentrations at the top and bottom of the two-sided 95 percent confidence interval also specified). C. Determination of minimum sample counting times required for detection and/or quantification of specified alpha and beta activities or air activity concentrations. In addition, alternate counting times are determined for alternate activities such that the specified alpha and beta activities are at the top of the 95% confidence interval, increasing the confidence that the activities measured are below the specified limits. D. Calculation of the minimum detectable activities or air activity concentrations. E. Determination of air sample volumes required for detection and/or quantification of specified alpha and beta air activity concentrations. F. Calculation of long-lived activities or air activity concentrations based on radon daughter and thoron daughter decay. G. Calculation of employees DAC-Hours and estimated Committed Effective Dose Equivalent. H. Varying calibration constants (to coincide with possible adjustments to

  1. Channel capacity of an array system for Gaussian channels with applications to combining and noise cancellation

    NASA Technical Reports Server (NTRS)

    Cheung, K. M.; Vilnrotter, V.

    1996-01-01

    A closed-form expression for the capacity of an array of correlated Gaussian channels is derived. It is shown that when signal and noise are independent, the array of observables can be replaced with a single observable without diminishing the capacity of the array channel. Examples are provided to illustrate the dependence of channel capacity on noise correlation for two- and three-channel arrays.

  2. Channel Capacity of an Array System for Gaussian Channels With Applications to Combining and Noise Cancellation

    NASA Technical Reports Server (NTRS)

    Cheung, K.-M.; Vilnrotter, V.

    1996-01-01

    A closed-form expression for the capacity of an array of correlated Gaussian channels is derived. It is shown that when signal and noise are independent, the array of observables can be replaced with a single observable without diminishing the capacity of the array channel. Examples are provided to illustrate the dependence of channel capacity on noise correlation for two- and three-channel arrays.

  3. A Multiple-Channel Sub-Band Transient Detection System

    SciTech Connect

    David A. Smith

    1998-11-01

    We have developed a unique multiple-channel sub-band transient detection system to record transient electromagnetic signals in carrier-dominated radio environments; the system has been used to make unique observations of weak, transient HF signals. The detection system has made these observations possible through improved sensitivity compared to conventional broadband transient detection systems; the sensitivity improvement is estimated to be at least 20 dB. The increase in sensitivity has been achieved through subdivision of the band of interest (an 18 MHz tunable bandwidth) into eight sub-band independent detection channels, each with a 400 kHz bandwidth and its own criteria. The system generates a system trigger signal when a predetermined number of channels (typically five) trigger within a predetermined window of time (typically 100 ~s). Events are recorded with a broadband data acquisition system sampling at 50 or 100 Msample/s, so despite the fact that the detection system operates on portions of the signal confined to narrow bands, data acquisition is broadband. Between May and September of 1994, the system was used to detect and record over six thousand transient events in the frequency band from 3 to 30 MHz. Approximately 500 of the events have been characterized as paired bursts of radio noise with individual durations of 2 to 10 ps and separations between the bursts of 5 to 160 ps. The paired transients are typically 5 to 40 dB brighter than the background electromagnetic spectrum between carrier signals. We have termed these events SubIonospheric Pulse Pairs (SIPPS) and presently have no explanation as to their source. Our observations of SIPPS resemble observations of TransIonospheric Pulse Pairs (TIPPs) recorded by the Blackboard instrument on the ALEXIS satellite; the source of TIPP events is also unknown. Most of the recorded SIPP events do not exhibit frequency dispersion, implying propagation along a line-of-sight (groundwave) path; but seven of

  4. Systems Modeling of a Hypothetical SSME Channel-Wall Nozzle

    NASA Technical Reports Server (NTRS)

    Greene, William D.; Thames, Mignon P.; Polsgrove, Robert H.

    2003-01-01

    A future upgrade to the Space Shuttle Main Engine (SSME) may be the replacement of the current regenerative cooled tube-wall nozzle with a nozzle using a regeneratively-cooled channel-wall design. The current tube-wall design represents the only major piece of SSME hardware that has not been dramatically updated throughout thc long history of the engine. There are a number of advantages to a channel-wall design including the promise of faster and lower cost fabrication and greater reliability in the field. The technical obstacles in the path of making this happen are many, particularly in the realms of metallurgy and manufacturing techniques. However, one technical area that can and should be addressed in the near term as part of the development of detailed component requirements is a systems type model of the fluid flow and heat transfer processes to which the new design will be exposed. This paper presents the results of an effort to develop a mathematical model of the internal flow for a generic channel-wall nozzle functioning as a direct replacement for the current tube-wall nozzle with a minimum of systems-level changes. Comparisons will be made to mathematical modeling results for the current tube-wall design and the results of various geometrical trade studies will be presented. It is the intent of this work to examine the feasibility of the concept of a direct replacement component with minimum systems-!eve impacts and to highlight potential areas of concern requiring further work in the future.

  5. Channeling power across ecological systems: social regularities in community organizing.

    PubMed

    Christens, Brian D; Inzeo, Paula Tran; Faust, Victoria

    2014-06-01

    Relational and social network perspectives provide opportunities for more holistic conceptualizations of phenomena of interest in community psychology, including power and empowerment. In this article, we apply these tools to build on multilevel frameworks of empowerment by proposing that networks of relationships between individuals constitute the connective spaces between ecological systems. Drawing on an example of a model for grassroots community organizing practiced by WISDOM—a statewide federation supporting local community organizing initiatives in Wisconsin—we identify social regularities (i.e., relational and temporal patterns) that promote empowerment and the development and exercise of social power through building and altering relational ties. Through an emphasis on listening-focused one-to-one meetings, reflection, and social analysis, WISDOM organizing initiatives construct and reinforce social regularities that develop social power in the organizing initiatives and advance psychological empowerment among participant leaders in organizing. These patterns are established by organizationally driven brokerage and mobilization of interpersonal ties, some of which span ecological systems.Hence, elements of these power-focused social regularities can be conceptualized as cross-system channels through which micro-level empowerment processes feed into macro-level exercise of social power, and vice versa. We describe examples of these channels in action, and offer recommendations for theory and design of future action research [corrected] . PMID:24398621

  6. Traveling Wave RF Systems for Helical Cooling Channels

    SciTech Connect

    Yonehara, K.; Lunin, A.; Moretti, A.; Popovic, M.; Romanov, G.; Neubauer, M.; Johnson, R.P.; Thorndahl, L.; /CERN

    2009-05-01

    The great advantage of the helical ionization cooling channel (HCC) is its compact structure that enables the fast cooling of muon beam 6-dimensional phase space. This compact aspect requires a high average RF gradient, with few places that do not have cavities. Also, the muon beam is diffuse and requires an RF system with large transverse and longitudinal acceptance. A traveling wave system can address these requirements. First, the number of RF power coupling ports can be significantly reduced compared with our previous pillbox concept. Secondly, by adding a nose on the cell iris, the presence of thin metal foils traversed by the muons can possibly be avoided. We show simulations of the cooling performance of a traveling wave RF system in a HCC, including cavity geometries with inter-cell RF power couplers needed for power propagation.

  7. Superchannel transmission system based on multi-channel equalization.

    PubMed

    Zeng, Tao

    2013-06-17

    We proposed a new method for superchannel transmission based on the newly proposed multi-channel equalization technique. This method allows us to realize tight channel spacing (equal to the baud rate) without using frequency-locked lasers and complex spectral shaping techniques at the transmitter. The inter-channel interference originated from the tight channel spacing is removed at the receiver by joint equalization of multiple adjacent channels. When the channel spacing is equal to the baud rate, our simulation results show that, with conventional oversample ratio (2 samples per symbol), realistic laser frequency offset and laser linewidth, the proposed multi-channel-equalization based method can achieve better performance than the traditional method using spectral shaping plus single channel equalization, although at the expense of a moderate increase in DSP complexity. The paper also gives a simple method to process the data after conventional chromatic dispersion compensation, which enables subsequent multi-channel equalization for long-haul transmissions. PMID:23787667

  8. 47 CFR 22.757 - Channels for basic exchange telephone radio systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Channels for basic exchange telephone radio... CARRIER SERVICES PUBLIC MOBILE SERVICES Rural Radiotelephone Service Basic Exchange Telephone Radio Systems § 22.757 Channels for basic exchange telephone radio systems. The channels listed in § 22.725...

  9. 47 CFR 22.757 - Channels for basic exchange telephone radio systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Channels for basic exchange telephone radio... CARRIER SERVICES PUBLIC MOBILE SERVICES Rural Radiotelephone Service Basic Exchange Telephone Radio Systems § 22.757 Channels for basic exchange telephone radio systems. The channels listed in § 22.725...

  10. 47 CFR 22.757 - Channels for basic exchange telephone radio systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Channels for basic exchange telephone radio... CARRIER SERVICES PUBLIC MOBILE SERVICES Rural Radiotelephone Service Basic Exchange Telephone Radio Systems § 22.757 Channels for basic exchange telephone radio systems. The channels listed in § 22.725...

  11. 47 CFR 22.757 - Channels for basic exchange telephone radio systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Channels for basic exchange telephone radio... CARRIER SERVICES PUBLIC MOBILE SERVICES Rural Radiotelephone Service Basic Exchange Telephone Radio Systems § 22.757 Channels for basic exchange telephone radio systems. The channels listed in § 22.725...

  12. 47 CFR 22.757 - Channels for basic exchange telephone radio systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Channels for basic exchange telephone radio... CARRIER SERVICES PUBLIC MOBILE SERVICES Rural Radiotelephone Service Basic Exchange Telephone Radio Systems § 22.757 Channels for basic exchange telephone radio systems. The channels listed in § 22.725...

  13. A portable fNIRS system with eight channels

    NASA Astrophysics Data System (ADS)

    Si, Juanning; Zhao, Ruirui; Zhang, Yujin; Zuo, Nianming; Zhang, Xin; Jiang, Tianzi

    2015-03-01

    Abundant study on the hemodynamic response of a brain have brought quite a few advances in technologies of measuring it. The most benefitted is the functional near infrared spectroscope (fNIRS). A variety of devices have been developed for different applications. Because portable fNIRS systems were more competent to measure responses either of special subjects or in natural environment, several kinds of portable fNIRS systems have been reported. However, they all required a computer for receiving data. The extra computer increases the cost of a fNIRS system. What's more noticeable is the space required to locate the computer even for a portable system. It will discount the portability of the fNIRS system. So we designed a self-contained eight channel fNIRS system, which does not demand a computer to receive data and display data in a monitor. Instead, the system is centered by an ARM core CPU, which takes charge in organizing data and saving data, and then displays data on a touch screen. The system has also been validated by experiments on phantoms and on subjects in tasks.

  14. Electromagnetic instability in an electron beam-ion channel system

    NASA Astrophysics Data System (ADS)

    Su, D.; Tang, C. J.

    2009-05-01

    The transverse electromagnetic instability in the electron beam-ion channel system is investigated using kinetic theory. The equilibrium distribution function of a relativistic electron beam, which takes into account a strong ion channel effect, is obtained. The linearized Vlasov equation is solved and the dispersion relation of the system is derived by perturbing the equilibrium with a high frequency electromagnetic wave (EMW). Analysis of the dispersion relation shows that the coupling of the electron beam with the transverse high frequency EMW is achieved through the deflection of the beam electrons due to the synergistic effects of the transverse high frequency EMW and transverse betatron oscillation. The numerical calculation finds that a branch of slow wave instability (SWI) with a wide frequency band is excited. The attenuation index of the SWI increases and its frequency band broadens as the normalized beam radii increases. Besides, the SWI will be suppressed as the longitudinal velocity of the electron beam increases to a certain value; meanwhile, a bunch of fast wave instability (FWI) is excited, which is equal to the increase of the relativistic factor. Also both the SWI and the FWI reach maximum when the EMW frequency meets a resonance condition.

  15. Application of a multi-channel system for continuous monitoring and an early warning system.

    PubMed

    Lee, J H; Song, C H; Kim, B C; Gu, M B

    2006-01-01

    A multi-channel continuous toxicity monitoring system developed in our laboratory, based on two-stage mini-bioreactors, was successfully implemented in the form of computer-based data acquisition. The multi-channel system consists of a series of a two-stage minibioreactor systems connected by a fiber optic probe to a luminometer, and uses genetically engineered bioluminescent bacteria for the detection of the potential toxicity from the soluble chemicals. This system can be stably and continuously operated due to the separation of the culture reactor from the test reactor and accomplish easy and long-term monitoring without system shut down by abrupt inflows of severe polluting chemicals. Four different recombinant bioluminescent bacteria were used in different channels so that the modes of the samples toxicities can be reasonably identified and evaluated based upon the response signature of each channel. The bioluminescent signatures were delivered from four channels by switching one at once, while the data is automatically logged to an IBM compatible computer. We also achieved the enhancement of the system through the manipulation of the dilution rate and the use of thermo-lux fusion strains. Finally, this system is now being implemented to a drinking water reservoir and river for remote sensing as an early warning system. PMID:16722085

  16. 47 CFR 22.1007 - Channels for offshore radiotelephone systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... channels are contained in UHF TV Channel 16. (c) Zone C—Southern Texas. The geographical area in Zone C is... Channel 17. (b) Zone B—Southern Louisiana—Texas. (1) The geographical area in Zone B is bounded as...

  17. Cascaded coherent tracking systems with time-varying channels. [for spacecraft

    NASA Technical Reports Server (NTRS)

    Weber, W. J., III; Yuen, J. H.

    1976-01-01

    A performance analysis is presented of a two-way coherent tracking system (of the type used for spacecraft tracking and navigation) in which the transmitted signals have pass through linear time-varying channels. The performance of the system is characterized by the steady state probability density function of the reduced phase error process in the second tracking loop, the system considered consisting of two first-order phase locked loops in cascade. While the log normal channel, which arises in communication through planetary atmospheres, was used as the channel model, the results can be extended to other channels, such as the Rice and Rayleigh channels.

  18. Study of dual-channel infrared spectroradiometer systems

    NASA Technical Reports Server (NTRS)

    Wrubel, J. A.

    1973-01-01

    A dual channel infrared spectroradiometer system was installed at a high altitude facility where spectral data were obtained from F2/H2, FLOX/CH4, FLOX/B2H6, OF2/CH4, and OF2/B2H6 propellant combinations. A good HF emission spectra was obtained for tests with the OF2B2H6 propellant combination. Subsequently, data were obtained on the LOX/GH2 propellant combination at sea level and altitude conditions that were inconsistent because the calculation of plume properties led to physically unrealistic results. The inconsistencies resulted from measurement accuracy not being within the narrow limits required by the data reduction scheme. Although the anticipated program results were not obtained, the data gathered are useful for guiding future experimental efforts and formulations of less sensitive analytical models.

  19. Single transmission line interrogated multiple channel data acquisition system

    DOEpatents

    Fasching, George E.; Keech, Jr., Thomas W.

    1980-01-01

    A single transmission line interrogated multiple channel data acquisition system is provided in which a plurality of remote station/sensor circuits each monitors a specific process variable and each transmits measurement values over a single transmission line to a master interrogating station when addressed by said master interrogating station. Typically, as many as 330 remote stations may be parallel connected to the transmission line which may exceed 7,000 feet. The interrogation rate is typically 330 stations/second. The master interrogating station samples each station according to a shared, charging transmit-receive cycle. All remote station address signals, all data signals from the remote stations/sensors and all power for all of the remote station/sensors are transmitted via a single continuous terminated coaxial cable. A means is provided for periodically and remotely calibrating all remote sensors for zero and span. A provision is available to remotely disconnect any selected sensor station from the main transmission line.

  20. Control system devices : architectures and supply channels overview.

    SciTech Connect

    Trent, Jason; Atkins, William Dee; Schwartz, Moses Daniel; Mulder, John C.

    2010-08-01

    This report describes a research project to examine the hardware used in automated control systems like those that control the electric grid. This report provides an overview of the vendors, architectures, and supply channels for a number of control system devices. The research itself represents an attempt to probe more deeply into the area of programmable logic controllers (PLCs) - the specialized digital computers that control individual processes within supervisory control and data acquisition (SCADA) systems. The report (1) provides an overview of control system networks and PLC architecture, (2) furnishes profiles for the top eight vendors in the PLC industry, (3) discusses the communications protocols used in different industries, and (4) analyzes the hardware used in several PLC devices. As part of the project, several PLCs were disassembled to identify constituent components. That information will direct the next step of the research, which will greatly increase our understanding of PLC security in both the hardware and software areas. Such an understanding is vital for discerning the potential national security impact of security flaws in these devices, as well as for developing proactive countermeasures.

  1. Emerging concepts for the role of TRP channels in the cardiovascular system

    PubMed Central

    Vennekens, Rudi

    2011-01-01

    Abstract The transient receptor potential (TRP) family of ion channels is a large family of cation selective ion channels, which are expressed and functional in a variety of tissues. In this review we focus on the most recent results detailing the role of TRP channels in the cardiovascular system. The presented results underscore the role of TRP channels in cardiomyocytes, smooth cells and endothelium, and in disease states such as hypertension, cardiac conduction block and cardiac hypertrophy. PMID:21173080

  2. In-service communication channel sensing based on reflectometry for TWDM-PON systems

    NASA Astrophysics Data System (ADS)

    Iida, Daisuke; Kuwano, Shigeru; Terada, Jun

    2014-05-01

    Many base stations are accommodated in TWDM-PON based mobile backhaul and fronthaul networks for future radio access, and failed connections in an optical network unit (ONU) wavelength channel severely degrade system performance. A cost effective in-service ONU wavelength channel monitor is essential to ensure proper system operation without failed connections. To address this issue we propose a reflectometry-based remote sensing method that provides wavelength channel information with the optical line terminal (OLT)-ONU distance. The method realizes real-time monitoring of ONU wavelength channels without signal quality degradation. Experimental results show it achieves wavelength channel distinction with high distance resolution.

  3. Flexible waveguide enabled single-channel terahertz endoscopic system

    NASA Astrophysics Data System (ADS)

    Doradla, Pallavi; Alavi, Karim; Joseph, Cecil S.; Giles, Robert H.

    2015-03-01

    Colorectal cancer is the third most commonly diagnosed cancer in the world. The current standard of care for colorectal cancer is the conventional colonoscopy, which relies exclusively on the Physician's experience. Continuous wave terahertz (THz) imaging has the potential to offer a safe, noninvasive medical imaging modality for detecting cancers. The current study demonstrates the design and development of a prototype terahertz endoscopic system based on flexible metal-coated terahertz waveguides. A CO2 pumped Far-Infrared molecular gas laser operating at 584 GHz frequency was used for illuminating the tissue, while the reflected signals were detected using liquid Helium cooled silicon bolometer. The continuous-wave terahertz imaging system utilizes a single waveguide channel to transmit the radiation and collect the back reflected intrinsic terahertz signal from the sample and is capable of operation in both transmission and reflection modalities. The two dimensional reflectance images obtained using a prototype terahertz endoscopic system showed intrinsic contrast between cancerous and normal regions of the colorectal tissue, thereby demonstrating the potential impact of terahertz imaging for in vivo cancer detection.

  4. Cluster system using fiber channel as an interconnection network analysis

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Cao, Mingcui; Luo, Zhixiang

    2005-02-01

    In the parallel processing system, large numbers of processors are interconnected in order to improve the performance of the computer, such as the symmetric multiprocessor (SMP) architecture. When the basic node is an SMP or a computer having a single processor, the characteristics of an interconnection networks are important factors which influence the performance of the entire system. Fibre Channel (FC) has a lot advantages, such as excellent scalability; the bandwidth is large; delay time is short and fault tolerance is large. It is assumed that an SMP is used for a basic node. We construct the cluster system using FC as interconnection network, which are a fabric method and a FC Arbitrated Loop (FC-AL) method. According the method, if the number of nodes supported by the interconnection network is small, the addition of extra nodes can be added at small expense. The bandwidth of each node is large, the delay time is short, and the fault tolerance effect is large in the interconnection network. In the case of connecting to a shared disk, a large bandwidth is provided and time required for gaining access to the shared disk becomes short.

  5. Speed of disentanglement in multiqubit systems under a depolarizing channel

    SciTech Connect

    Zhang, Fu-Lin Jiang, Yue; Liang, Mai-Lin

    2013-06-15

    We investigate the speed of disentanglement in the multiqubit systems under the local depolarizing channel, in which each qubit is independently coupled to the environment. We focus on the bipartition entanglement between one qubit and the remaining qubits constituting the system, which is measured by the negativity. For the two-qubit system, the speed for the pure state completely depends on its entanglement. The upper and lower bounds of the speed for arbitrary two-qubit states, and the necessary conditions for a state achieving them, are obtained. For the three-qubit system, we study the speed for pure states, whose entanglement properties can be completely described by five local-unitary-transformation invariants. An analytical expression of the relation between the speed and the invariants is derived. The speed is enhanced by the three-tangle which is the entanglement among the three qubits, but reduced by the two-qubit correlations outside the concurrence. The decay of the negativity can be restrained by the other two negativity with the coequal sense. The unbalance between two qubits can reduce the speed of disentanglement of the remaining qubit in the system, and even can retrieve the entanglement partially. For the k-qubit systems in an arbitrary superposition of Greenberger–Horne–Zeilinger state and W state, the speed depends almost entirely on the amount of the negativity when k increases to five or six. An alternative quantitative definition for the robustness of entanglement is presented based on the speed of disentanglement, with comparison to the widely studied robustness measured by the critical amount of noise parameter where the entanglement vanishes. In the limit of large number of particles, the alternative robustness of the Greenberger–Horne–Zeilinger-type states is inversely proportional to k, and the one of the W states approaches 1/√(k)

  6. A Study on Channel Estimation Methods for Time-Domain Spreading MC-CDMA Systems

    NASA Astrophysics Data System (ADS)

    Nagate, Atsushi; Fujii, Teruya

    As a candidate for the transmission technology of next generation mobile communication systems, time-domain spreading MC-CDMA systems have begun to attract much attention. In these systems, data and pilot symbols are spread in the time domain and code-multiplexed. To combat fading issues, we need to conduct channel estimation by using the code-multiplexed pilot symbols. Especially in next generation systems, frequency bands higher than those of current systems, which raise the maximum Doppler frequency, are expected to be used, so that a more powerful channel estimation method is expected. Considering this, we propose a channel estimation method for highly accurate channel estimation; it is a combination of a two-dimensional channel estimation method and an impulse response-based channel estimation method. We evaluate the proposed method by computer simulations.

  7. Channel coding and data compression system considerations for efficient communication of planetary imaging data

    NASA Technical Reports Server (NTRS)

    Rice, R. F.

    1974-01-01

    End-to-end system considerations involving channel coding and data compression which could drastically improve the efficiency in communicating pictorial information from future planetary spacecraft are presented.

  8. Validation of statistical channel models for 60 GHz radio systems in hospital environments.

    PubMed

    Kyrö, Mikko; Takizawa, Ken-ichi; Haneda, Katsuyuki; Vainikainen, Pertti

    2013-05-01

    Statistical channel models for 60 GHz communications systems in hospital environments are validated using channel capacity and throughput of a physical layer as figures of merit. The channel models are validated by comparing the performance figures with channels from the measurements and the channel models. The throughput evaluation is based on system specifications given by the IEEE 802.15.3 c standard for high data rate wireless personal area networks, namely orthogonal frequency division multiplexing and single carrier transmissions. The channel capacity serves as a metric of the potential of the two transmission schemes since it defines the upper bound of the throughput. The capacity is derived based on the signal formats of the transmission schemes. The capacity shows that 97 % of the measurement results are within 2σ range of the modeled results. The throughput shows that the channel models predict the maximum achievable throughput of the measured channels precisely, while the mean throughput in some cases shows difference because of the interpolation effect of the small-scale fading in the statistical channel models. Due to the interpolation effect, the channel model is more suitable for a precise analysis of the outage performance than the measurements where the number of channel samples is limited and the worst faded channels are not necessarily included. PMID:23221798

  9. Nicotine effect on cardiovascular system and ion channels.

    PubMed

    Hanna, Salma Toma

    2006-03-01

    Smoking is a leading cause of cardiovascular disease, hypertension, myocardial infarction, and stroke. Nicotine is one of the components of cigarette smoke. Nicotine effects on the cardiovascular system reflect the activity of the nicotine receptors centrally and on peripheral autonomic ganglia. It has been found that cigarette smoke extract-induced contraction of porcine coronary arteries is related to superoxide anion-mediated degradation of nitric oxide. Treatment of rabbit aortas with an oxygen free radicals scavenger attenuated cigarette smoke impairment of arterial relaxation. Treatment of smokers with vitamin C, an antioxidant, improved impaired endothelium-dependent reactivity of large peripheral arteries. Thus it appears that chronic smoking and acute exposure to cigarette smoke extract may alter endothelium-dependent reactivity via the production of oxygen derived free radicals. This review discusses the effects of nicotine on resistance arterioles, compliance arteries, smooth muscle cells, and ion channels in the cardiovascular system. We discuss studies performed on humans, nicotine-exposed animals, and cell cultures yielding varying and inconsistent results that may be due to differences in experimental design, species, and the dose of exposure. Nicotine exposure appears to induce a combination of free radical production, vascular wall adhesion, and a reduction of fibrinolytic activity in the plasma. PMID:16633075

  10. Viral potassium channels as a robust model system for studies of membrane-protein interaction.

    PubMed

    Braun, Christian J; Lachnit, Christine; Becker, Patrick; Henkes, Leonhard M; Arrigoni, Cristina; Kast, Stefan M; Moroni, Anna; Thiel, Gerhard; Schroeder, Indra

    2014-04-01

    The viral channel KcvNTS belongs to the smallest K(+) channels known so far. A monomer of a functional homotetramer contains only 82 amino acids. As a consequence of the small size the protein is almost fully submerged into the membrane. This suggests that the channel is presumably sensitive to its lipid environment. Here we perform a comparative analysis for the function of the channel protein embedded in three different membrane environments. 1. Single-channel currents of KcvNTS were recorded with the patch clamp method on the plasma membrane of HEK293 cells. 2. They were also measured after reconstitution of recombinant channel protein into classical planar lipid bilayers and 3. into horizontal bilayers derived from giant unilamellar vesicles (GUVs). The recombinant channel protein was either expressed and purified from Pichia pastoris or from a cell-free expression system; for the latter a new approach with nanolipoprotein particles was used. The data show that single-channel activity can be recorded under all experimental conditions. The main functional features of the channel like a large single-channel conductance (80pS), high open-probability (>50%) and the approximate duration of open and closed dwell times are maintained in all experimental systems. An apparent difference between the approaches was only observed with respect to the unitary conductance, which was ca. 35% lower in HEK293 cells than in the other systems. The reason for this might be explained by the fact that the channel is tagged by GFP when expressed in HEK293 cells. Collectively the data demonstrate that the small viral channel exhibits a robust function in different experimental systems. This justifies an extrapolation of functional data from these systems to the potential performance of the channel in the virus/host interaction. This article is part of a Special Issue entitled: Viral Membrane Proteins-Channels for Cellular Networking. PMID:23791706

  11. Compressive sensing based Bayesian sparse channel estimation for OFDM communication systems: high performance and low complexity.

    PubMed

    Gui, Guan; Xu, Li; Shan, Lin; Adachi, Fumiyuki

    2014-01-01

    In orthogonal frequency division modulation (OFDM) communication systems, channel state information (CSI) is required at receiver due to the fact that frequency-selective fading channel leads to disgusting intersymbol interference (ISI) over data transmission. Broadband channel model is often described by very few dominant channel taps and they can be probed by compressive sensing based sparse channel estimation (SCE) methods, for example, orthogonal matching pursuit algorithm, which can take the advantage of sparse structure effectively in the channel as for prior information. However, these developed methods are vulnerable to both noise interference and column coherence of training signal matrix. In other words, the primary objective of these conventional methods is to catch the dominant channel taps without a report of posterior channel uncertainty. To improve the estimation performance, we proposed a compressive sensing based Bayesian sparse channel estimation (BSCE) method which cannot only exploit the channel sparsity but also mitigate the unexpected channel uncertainty without scarifying any computational complexity. The proposed method can reveal potential ambiguity among multiple channel estimators that are ambiguous due to observation noise or correlation interference among columns in the training matrix. Computer simulations show that proposed method can improve the estimation performance when comparing with conventional SCE methods. PMID:24983012

  12. K/Ka-band channel characterization for mobile satellite systems

    NASA Technical Reports Server (NTRS)

    Pinck, Deborah S.; Rice, Michael D.

    1995-01-01

    Mobile satellite systems allow truly ubiquitous wireless communications to users anywhere and anytime. NASA's Advanced Communications Technology Satellite (ACTS) provides an ideal space-based platform for the measurement of K/Ka band propagation characteristics in a land mobile satellite application. Field tests conducted in Southern California during the first seven months of 1994 using JPL's ACTS Mobile Terminal (AMT) provided channel characterization data for the K/Ka-band link. A pilot tone was transmitted from a fixed station in Cleveland, Ohio through the satellite and downlinked at 20 GHz in the Southern California spot beam. The AMT was equipped with a narrow beam, high gain antenna which tracked the satellite in azimuth for a fixed elevation angle (46 degrees for this case). The field tests were conducted in three basic environments: clear line-of-sight (LOS) highways, lightly shadowed suburban, and heavily shadowed suburban. Preliminary results of these field tests indicate very little multipath for rural environments and for clear LOS links (as expected with a narrow beam antenna). Deep fades were experienced in shadowed areas, especially those where tree canopies covered the road.

  13. The activity of the TRP-like channel depends on its expression system

    PubMed Central

    Lev, Shaya; Katz, Ben; Minke, Baruch

    2012-01-01

    The Drosophila light activated TRP and TRPL channels have been a model for TRPC channel gating. Several gating mechanisms have been proposed following experiments conducted on photoreceptor and tissue cultured cells. However, conclusive evidence for any mechanism is still lacking. Here, we show that the Drosophila TRPL channel expressed in tissue cultured cells is constitutively active in S2 cells but is silent in HEK cells. Modulations of TRPL channel activity in different expression system by pharmacology or specific enzymes, which change the lipid content of the plasma membrane, resulted in conflicting effects. These findings demonstrate the difficulty in elucidating TRPC gating, as channel behavior is expression system dependent. However, clues on the gating mechanism may arise from understanding how different expression systems affect TRPC channel activation. PMID:22627924

  14. Average capacity for optical wireless communication systems over exponentiated Weibull distribution non-Kolmogorov turbulent channels.

    PubMed

    Cheng, Mingjian; Zhang, Yixin; Gao, Jie; Wang, Fei; Zhao, Fengsheng

    2014-06-20

    We model the average channel capacity of optical wireless communication systems for cases of weak to strong turbulence channels, using the exponentiation Weibull distribution model. The joint effects of the beam wander and spread, pointing errors, atmospheric attenuation, and the spectral index of non-Kolmogorov turbulence on system performance are included. Our results show that the average capacity decreases steeply as the propagation length L changes from 0 to 200 m and decreases slowly down or tends to a stable value as the propagation length L is greater than 200 m. In the weak turbulence region, by increasing the detection aperture, we can improve the average channel capacity and the atmospheric visibility as an important issue affecting the average channel capacity. In the strong turbulence region, the increase of the radius of the detection aperture cannot reduce the effects of the atmospheric turbulence on the average channel capacity, and the effect of atmospheric visibility on the channel information capacity can be ignored. The effect of the spectral power exponent on the average channel capacity in the strong turbulence region is higher than weak turbulence region. Irrespective of the details determining the turbulent channel, we can say that pointing errors have a significant effect on the average channel capacity of optical wireless communication systems in turbulence channels. PMID:24979434

  15. 47 CFR 22.857 - Channel plan for commercial aviation air-ground systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Channel plan for commercial aviation air-ground... CARRIER SERVICES PUBLIC MOBILE SERVICES Air-Ground Radiotelephone Service Commercial Aviation Air-Ground Systems § 22.857 Channel plan for commercial aviation air-ground systems. The 849-851 MHz and 894-896...

  16. 47 CFR 22.857 - Channel plan for commercial aviation air-ground systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Channel plan for commercial aviation air-ground... CARRIER SERVICES PUBLIC MOBILE SERVICES Air-Ground Radiotelephone Service Commercial Aviation Air-Ground Systems § 22.857 Channel plan for commercial aviation air-ground systems. The 849-851 MHz and 894-896...

  17. 47 CFR 22.857 - Channel plan for commercial aviation air-ground systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Channel plan for commercial aviation air-ground... CARRIER SERVICES PUBLIC MOBILE SERVICES Air-Ground Radiotelephone Service Commercial Aviation Air-Ground Systems § 22.857 Channel plan for commercial aviation air-ground systems. The 849-851 MHz and 894-896...

  18. 47 CFR 22.857 - Channel plan for commercial aviation air-ground systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Channel plan for commercial aviation air-ground... CARRIER SERVICES PUBLIC MOBILE SERVICES Air-Ground Radiotelephone Service Commercial Aviation Air-Ground Systems § 22.857 Channel plan for commercial aviation air-ground systems. The 849-851 MHz and 894-896...

  19. Performance of a temperate-zone channel catfish biofloc technology production system during winter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Channel catfish (Ictalurus punctatus) have been grown successfully in an outdoor biofloc technology production system. Outdoor biofloc production systems in the tropics are operated year-round, whereas the channel catfish studies were conducted only during the growing season and biofloc production t...

  20. 47 CFR 22.857 - Channel plan for commercial aviation air-ground systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Channel plan for commercial aviation air-ground systems. 22.857 Section 22.857 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Air-Ground Radiotelephone Service Commercial Aviation Air-Ground Systems § 22.857 Channel plan...

  1. Performance Characterization of a Hybrid Satellite-Terrestrial System with Co-Channel Interference over Generalized Fading Channels.

    PubMed

    Javed, Umer; He, Di; Liu, Peilin

    2016-01-01

    The transmission of signals in a hybrid satellite-terrestrial system (HSTS) in the presence of co-channel interference (CCI) is considered in this study. Specifically, we examine the problem of amplify-and-forward (AF)-based relaying in a hybrid satellite-terrestrial link, where the relay node is operating in the presence of a dominant co-channel interferer. It is assumed that direct connection between a source node (satellite) and a destination node (terrestrial receiver) is not available due to masking by obstacles in the surrounding. The destination node is only able to receive signals from the satellite with the help of a relay node located at the ground. In the proposed HSTS, the satellite-relay channel follows the shadowed Rice fading; and the channels of interferer-relay and relay-destination links experience generalized Nakagami-m fading. For the considered AF-based HSTS, we first develop the analytical expression for the moment generating function (MGF) of the overall output signal-to-interference-plus-noise ratio (SINR). Then, based on the derived exact MGF, we derive novel expressions for the average symbol error rate (SER) of the considered HSTS for the following digital modulation techniques: M-ary phase shift keying (M-PSK), M-ary quadrature amplitude modulation (M-QAM) and M-ary pulse amplitude modulation (M-PAM). To significantly reduce the computational complexity for utility in system-level simulations, simple analytical approximation for the exact SER in the high signal-to-noise ratio (SNR) regime is presented to provide key insights. Finally, numerical results and the corresponding analysis are presented to demonstrate the effectiveness of the developed performance evaluation framework and to view the impact of CCI on the considered HSTS under varying channel conditions and with different modulation schemes. PMID:27527182

  2. Drainage systems associated with mid-ocean channels and submarine Yazoos: Alternative to submarine fan depositional systems

    SciTech Connect

    Hesse, R. )

    1989-12-01

    Submarine drainage systems associated with mid-ocean channels and Yazoo River-type tributaries in small ocean basins represent a contrast to deep-sea fan depositional systems. Deep-sea fans are diverging sediment-dispersal systems of distributary fan valleys. Deep-sea channel-submarine-yazoo systems, on the other hand, form centripetally converging patterns of tributaries and yazoo-type satellite channels that join a major basin-draining (mid-ocean) channel. The facies model for such systems is characterized by randomly stacked fining-upward, gravelly, and sandy channel-fill and submarine point-bar sequences of the main channel encased in fine-grained overbank deposits. Second-order channels contain sandy proximal overbank deposits, whereas the levees of the main channel are predominantly composed of silt and clay. Second-order channels may be braided and may broaden into braid plains. Morphology and surficial sediment distribution have been studied within the Northwest Atlantic Mid-Ocean Channel of the Labrador Sea and its associated levees and yazoo-type (and other) tributaries.

  3. Linux-PC based 1024-Channel Transient Digitizer System for the DRIFT Experiment Acquisition System

    NASA Astrophysics Data System (ADS)

    Ayad, R.; Hanson-Hart, Z.; Hyatt, M.; Katz-Hyman, M.; Maher, P.; Martoff, C. J.; Posner, A.; Freytag, D.; Freytag, M.; Haller, G.; Nelson, D.

    2003-04-01

    The DRIFT Experiment [1] is an underground search for WIMP Dark Matter using a novel detector invented for this purpose: the Negative Ion TPC (NITPC). The data acquisition system for DRIFT had to allow acquisition of long duration time digitized data from the 1024 analog channels at an affordable price. This was accomplished with a system based on a Linux PC, the Comedi [2] open-source device driver software, the inexpensive PCI-DIO-32HS National Instruments high speed digital I/O board, and custom 32-channel preamp+digitizer boards built at SLAC. System architecture, testing, and performance will be discussed, as well as further upgrade plans. [1] Low Pressure Negative Ion TPC for Dark Matter Search. D. P. Snowden-Ifft, C. J. Martoff, J. M. Burwell, Phys Rev. D. Rapid Comm. 61, 101301 (2000) [2] Comedi: linux Control and MEasurement Device Interface : http://stm.lbl.gov/comedi/

  4. Modeling of nonstationary phenomena in the MHD-channel-inverter-substation system

    SciTech Connect

    Gusev, Y.P.; Zatelepin, V.N.; Kuznetsova, T.N.; Medin, S.A.; Pishchikov, V.I.

    1986-07-01

    A method for constructing a mathematical model of nonstationary phenomena in a system consisting of an MHD channel and an inverter substation, operating on a powerful ac grid, is examined. The variants of the realization of the model on a computer are discussed. Results of the solution of model problems with a diagonal MHD channel are presented. It is found that there is a significant coupling between the MHD channel and the inverter substation in transient processes.

  5. Design of all-reflective dual-channel foveated imaging systems based on freeform optics.

    PubMed

    Xu, Chen; Cheng, Dewen; Chen, Jinjin; Wang, Yongtian

    2016-03-20

    This paper presents a practical method to design all-reflective dual-channel foveated imaging systems. Such a system statically has two optical channels, one with a wider field-of-view for searching and another with a long focal length for fine reconnaissance. The two channels have a common center field angle. These systems may be useful for remote sensing where coarse searching and fine observation are simultaneously needed. To demonstrate the method, two corresponding systems are designed. The results reveal an angular resolution of finer than 4 arcsec for fine observation and a zoom ratio of 2.9× or 2.5× between the two channels. The modulation transfer function curves of both channels are above 0.3 at 100 line pairs per millimeter (lp/mm). Freeform surfaces are adopted to improve imaging quality and obtain a proper structure for fabrication. PMID:27140573

  6. RFI channels

    NASA Technical Reports Server (NTRS)

    Mceliece, R. J.

    1980-01-01

    A class of channel models is presented which exhibit varying burst error severity much like channels encountered in practice. An information-theoretic analysis of these channel models is made, and conclusions are drawn that may aid in the design of coded communication systems for realistic noisy channels.

  7. A three-channel miniaturized optical system for multi-resolution imaging

    NASA Astrophysics Data System (ADS)

    Belay, Gebirie Y.; Ottevaere, Heidi; Meuret, Youri; Thienpont, Hugo

    2013-09-01

    Inspired by the natural compound eyes of insects, multichannel imaging systems embrace many channels that scramble their entire Field-Of-View (FOV). Our aim in this work was to attain multi-resolution capability into a multi-channel imaging system by manipulating the available channels to possess different imaging properties (focal length, angular resolution). We have designed a three-channel imaging system where the first and third channels have highest and lowest angular resolution of 0.0096° and 0.078° and narrowest and widest FOVs of 7° and 80°, respectively. The design of the channels has been done for a single wavelength of 587.6 nm using CODE V. The three channels each consist of 4 aspherical lens surfaces and an absorbing baffle that avoids crosstalk among the neighbouring channels. The aspherical lens surfaces have been fabricated in PMMA by ultra-precision diamond tooling and the baffles by metal additive manufacturing. The profiles of the fabricated lens surfaces have been measured with an accurate multi-sensor coordinate measuring machine and compared with the corresponding profiles of the designed lens surfaces. The fabricated lens profiles are then incorporated into CODE V to realistically model the three channels and also compare their performances with those of the nominal design. We can conclude that the performances of the two latter models are in a good agreement.

  8. Progress towards a 256 channel multi-anode microchannel plate photomultiplier system with picosecond timing

    PubMed Central

    Lapington, J.S.; Ashton, T.J.R.; Ross, D.; Conneely, T.

    2012-01-01

    Despite the rapid advances in solid state technologies such as the silicon photomultiplier (SiPM), microchannel plate (MCP) photomultipliers still offer a proven and practical technological solution for high channel count pixellated photon-counting systems with very high time resolution. We describe progress towards a 256 channel optical photon-counting system using CERN-developed NINO and HTDC ASICs, and designed primarily for time resolved spectroscopy in life science applications. Having previously built and demonstrated a 18 mm diameter prototype tube with an 8×8 channel readout configuration and <43 ps rms single photon timing resolution, we are currently developing a 40 mm device with a 32×32 channel readout. Initially this will be populated with a 256 channel electronics system comprising four sets of modular 64 channel preamplifier/discriminator, and time-to-digital converter units, arranged in a compact three dimensional configuration. We describe the detector and electronics design and operation, and present performance measurements from the 256 channel development system. We discuss enhancements to the system including higher channel count and the use of application specific on-board signal processing capabilities. PMID:25843997

  9. BER analysis of TDD downlink multiuser MIMO systems with imperfect channel state information

    NASA Astrophysics Data System (ADS)

    Zhou, Baolong; Jiang, Lingge; Zhao, Shengjie; He, Chen

    2011-12-01

    In downlink multiuser multiple-input multiple-output (MU-MIMO) systems, the zero-forcing (ZF) transmission is a simple and effective technique for separating users and data streams of each user at the transmitter side, but its performance depends greatly on the accuracy of the available channel state information (CSI) at the transmitter side. In time division duplex (TDD) systems, the base station estimates CSI based on uplink pilots and then uses it through channel reciprocity to generate the precoding matrix in the downlink transmission. Because of the constraints of the TDD frame structure and the uplink pilot overhead, there inevitably exists CSI delay and channel estimation error between CSI estimation and downlink transmission channel, which degrades system performance significantly. In this article, by characterizing CSI inaccuracies caused by CSI delay and channel estimation error, we develop a novel bit error rate (BER) expression for M-QAM signal in TDD downlink MU-MIMO systems. We find that channel estimation error causes array gain loss while CSI delay causes diversity gain loss. Moreover, CSI delay causes more performance degradation than channel estimation error at high signal-to-noise ratio for time varying channel. Our research is especially valuable for the design of the adaptive modulation and coding scheme as well as the optimization of MU-MIMO systems. Numerical simulations show accurate agreement with the proposed analytical expressions.

  10. Instructional Design in Multi-Channel Learning System.

    ERIC Educational Resources Information Center

    Mukhopadhyay, Marmar; Parhar, Madhu

    2001-01-01

    Discusses instructional design and explains the multi-channel learning environment which was developed to allow the use of various media to provide alternative learning paths to accommodate differences in learning styles and media preferences. Highlights include taxonomies of learning; social aspects of learning; self-learning in distance…

  11. A wideband channel model for land mobile satellite systems

    NASA Technical Reports Server (NTRS)

    Jahn, Axel; Buonomo, Sergio; Sforza, Mario; Lutz, Erich

    1995-01-01

    A wideband channel model for Land Mobile Satellite (LMS) services is presented which characterizes the time-varying transmission channel between a satellite and a mobile user terminal. The channel model statistic parameters are the results of fitting procedures to measured data. The data used for fitting have a time resolution of 33 ns corresponding to a bandwidth of 30 MHz. Thus, the model is capable to characterize the channel behaviour for a wide range of services e.g., voice transmission, digital audio broadcasting (DAB), and spread spectrum modulation schemes. The model is presented for different environments and scenarios. The model is derived for a quasi-mobile user with hand-held terminal being in two different environments: rural and urban. The parameters needed for the description are (a) the number of echoes, (b) the distribution of the echo power, and (c) the distribution of the echo delay. It is shown that the direct path follows a Rician distribution whereas the reflected paths are Rayleigh/lognormal distributed. The parameters are given for an elevation angle of 25 deg.

  12. Pricing strategy in a dual-channel and remanufacturing supply chain system

    NASA Astrophysics Data System (ADS)

    Jiang, Chengzhi; Xu, Feng; Sheng, Zhaohan

    2010-07-01

    This article addresses the pricing strategy problems in a supply chain system where the manufacturer sells original products and remanufactured products via indirect retailer channels and direct Internet channels. Due to the complexity of that system, agent technologies that provide a new way for analysing complex systems are used for modelling. Meanwhile, in order to reduce the computational load of searching procedure for optimal prices and profits, a learning search algorithm is designed and implemented within the multi-agent supply chain model. The simulation results show that the proposed model can find out optimal prices of original products and remanufactured products in both channels, which lead to optimal profits of the manufacturer and the retailer. It is also found that the optimal profits are increased by introducing direct channel and remanufacturing. Furthermore, the effect of customer preference, direct channel cost and remanufactured unit cost on optimal prices and profits are examined.

  13. Formation of a helical channel in a 2D system in a quantum Hall regime

    NASA Astrophysics Data System (ADS)

    Kazakov, Aleksandr; Kolkovsky, V.; Adamus, Z.; Karczewski, G.; Wojtowicz, T.; Rokhinson, Leonid

    A two-dimensional system with reconfigurable network of one-dimensional p-wave superconducting channels is a perfect platform to perform braiding of non-Abelian excitations. Such channels can be realized in CdTe:Mn quantum wells in a quantum Hall effect regime, where counterpropagaring edge states with opposite spin polarization can be formed by electrostatic gating. These edges form helical channels similar to the edges of 2D topological insulators and, coupled to a superconductor, should support non-Abelian excitations. While long channels are localized at low temperatures, we found that resistance in short (<6 μm) helical channels remains finite at low temperatures. Transport data and resistance scaling with channel length will be presented. Work supported by ONR, National Science Centre (Poland) and Foundation for Polish Science.

  14. Wireless Channel Characterization in the 5 GHz Microwave Landing System Extension Band for Airport Surface Areas

    NASA Technical Reports Server (NTRS)

    Matolak, David W.

    2007-01-01

    In this project final report, entitled "Wireless Channel Characterization in the 5 GHz Microwave Landing System Extension Band for Airport Surface Areas," we provide a detailed description and model representation for the wireless channel in the airport surface environment in this band. In this executive summary, we review report contents, describe the achieved objectives and major findings, and highlight significant conclusions and recommendations.

  15. Destiny-yield relationship for channel catfish reared in a biofloc technology production system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of stocking density on yield of stocker channel catfish and water quality in a biofloc technology production system was studied in this completely randomized design experiment. Fingerling channel catfish (Ictalurus punctatus; 48.0 g/fish, 17.8 cm/fish) were stocked into nine continuously ...

  16. Solving non-Markovian open quantum systems with multi-channel reservoir coupling

    SciTech Connect

    Broadbent, Curtis J.; Jing, Jun; Yu, Ting; Eberly, Joseph H.

    2012-08-15

    We extend the non-Markovian quantum state diffusion (QSD) equation to open quantum systems which exhibit multi-channel coupling to a harmonic oscillator reservoir. Open quantum systems which have multi-channel reservoir coupling are those in which canonical transformation of reservoir modes cannot reduce the number of reservoir operators appearing in the interaction Hamiltonian to one. We show that the non-Markovian QSD equation for multi-channel reservoir coupling can, in some cases, lead to an exact master equation which we derive. We then derive the exact master equation for the three-level system in a vee-type configuration which has multi-channel reservoir coupling and give the analytical solution. Finally, we examine the evolution of the three-level vee-type system with generalized Ornstein-Uhlenbeck reservoir correlations numerically. - Highlights: Black-Right-Pointing-Pointer The concept of multi-channel vs. single-channel reservoir coupling is rigorously defined. Black-Right-Pointing-Pointer The non-Markovian quantum state diffusion equation for arbitrary multi-channel reservoir coupling is derived. Black-Right-Pointing-Pointer An exact time-local master equation is derived under certain conditions. Black-Right-Pointing-Pointer The analytical solution to the three-level system in a vee-type configuration is found. Black-Right-Pointing-Pointer The evolution of the three-level system under generalized Ornstein-Uhlenbeck noise is plotted for many parameter regimes.

  17. A tone-aided dual vestigial sideband system for digital communications on fading channels

    NASA Technical Reports Server (NTRS)

    Hladik, Stephen M.; Saulnier, Gary J.; Rafferty, William

    1989-01-01

    A spectrally efficient tone-aided dual vestigial sideband (TA/DVSB) system for digital data communications on fading channels is presented and described analytically. This PSK (phase-shift-keying) system incorporates a feed-forward, tone-aided demodulation technique to compensate for Doppler frequency shift and channel- induced, multipath fading. In contrast to other tone-in-band-type systems, receiver synchronization is derived from the complete data VSBs. Simulation results for the Rician fading channel are presented. These results demonstrate the receiver's ability to mitigate performance degradation due to fading and to obtain proper data carrier synchronization, suggesting that the proposed TA/DVSB system has promise for this application. Simulated BER (bit-error rate) data indicate that the TA/DVSB system effectively alleviates the channel distortions of the land mobile satellite application.

  18. Video-conversion channel of a synthesizing visualization system

    NASA Astrophysics Data System (ADS)

    Bogdaov, V. V.; Kovalev, A. M.; Nefedov, I. B.; Ponomarev, N. M.; Seroshtan, A. S.

    1986-08-01

    A video-conversion channel is described in which an analog video signal is generated according to the digital description of the video subject composed in terms of geometric primitives (line segments). The device contains units for the interpolation of object color, the simulation of atmospheric phenomena (e.g., fog and haze), the filtering of quantized images, and the gamma correction of the video signal.

  19. Global coverage Mobile Satellite Systems: System availability versus channel propagation impairments

    NASA Technical Reports Server (NTRS)

    Sforza, M.; Buonomo, S.; Poiaresbaptista, J. P. V.

    1993-01-01

    Mobile Satellite Systems (MSS) in Highly Elliptical (HEO) and circular Earth orbits at Medium (MEO) and Low (LEO) altitudes have been intensively studied in the last few years as an effective means of providing global communication services. Such global coverage MSS networks are also expected to mitigate typical channel impairments usually encountered in geostationary Land Mobile Satellite (LMS) systems. In the design stages of these satellite networks, information regarding the mobile propagation channel is needed to assess the overall link availability versus elevation angle and environmental scenarios. For multisatellite LMS configurations, the mobile user on the Earth surface sees, at any given time, more than one satellite of the constellation. In our paper, it is shown that, under certain working assumptions regarding the statistics of the propagation channel, an improvement of the link availability may be achieved through the use of a multisatellite constellation. The analyses have been carried out using the European Space Agency (ESA) LMS propagation data base which presently covers a wide range of elevation angles and environmental scenarios.

  20. Therapeutic targeting of two-pore-domain potassium (K(2P)) channels in the cardiovascular system.

    PubMed

    Wiedmann, Felix; Schmidt, Constanze; Lugenbiel, Patrick; Staudacher, Ingo; Rahm, Ann-Kathrin; Seyler, Claudia; Schweizer, Patrick A; Katus, Hugo A; Thomas, Dierk

    2016-05-01

    The improvement of treatment strategies in cardiovascular medicine is an ongoing process that requires constant optimization. The ability of a therapeutic intervention to prevent cardiovascular pathology largely depends on its capacity to suppress the underlying mechanisms. Attenuation or reversal of disease-specific pathways has emerged as a promising paradigm, providing a mechanistic rationale for patient-tailored therapy. Two-pore-domain K(+) (K(2P)) channels conduct outward K(+) currents that stabilize the resting membrane potential and facilitate action potential repolarization. K(2P) expression in the cardiovascular system and polymodal K2P current regulation suggest functional significance and potential therapeutic roles of the channels. Recent work has focused primarily on K(2P)1.1 [tandem of pore domains in a weak inwardly rectifying K(+) channel (TWIK)-1], K(2P)2.1 [TWIK-related K(+) channel (TREK)-1], and K(2P)3.1 [TWIK-related acid-sensitive K(+) channel (TASK)-1] channels and their role in heart and vessels. K(2P) currents have been implicated in atrial and ventricular arrhythmogenesis and in setting the vascular tone. Furthermore, the association of genetic alterations in K(2P)3.1 channels with atrial fibrillation, cardiac conduction disorders and pulmonary arterial hypertension demonstrates the relevance of the channels in cardiovascular disease. The function, regulation and clinical significance of cardiovascular K(2P) channels are summarized in the present review, and therapeutic options are emphasized. PMID:26993052

  1. Pulse-excited, auto-zeroing multiple channel data transmission system

    DOEpatents

    Fasching, George E.

    1987-01-01

    A multiple channel data transmission system is provided in which signals from a plurality of pulse operated transducers and a corresponding plurality of pulse operated signal processor channels are multiplexed for single channel FM transmission to a receiving station. The transducers and corresponding channel amplifiers are powered by pulsing the dc battery power to these devices to conserve energy and battery size for long-term data transmission from remote or inaccessible locations. Auto zeroing of the signal channel amplifiers to compensate for drift associated with temperature changes, battery decay, component aging, etc., in each channel is accomplished by means of a unique auto zero feature which between signal pulses holds a zero correction voltage on an integrating capacitor coupled to the corresponding channel amplifier output. Pseudo-continuous outputs for each channel are achieved by pulsed sample-and-hold circuits which are updated at the pulsed operation rate. The sample-and-hold outputs are multiplexed into an FM/FM transmitter for transmission to an FM receiver station for demultiplexing and storage in separate channel recorders.

  2. Pulse-excited, auto-zeroing multiple channel data transmission system

    DOEpatents

    Fasching, G.E.

    1985-02-22

    A multiple channel data transmission system is provided in which signals from a plurality of pulse operated transducers and a corresponding plurality of pulse operated signal processor channels are multiplexed for single channel FM transmission to a receiving station. The transducers and corresponding channel amplifiers are powered by pulsing the dc battery power to these devices to conserve energy and battery size for long-term data transmission from remote or inaccessible locations. Auto zeroing of the signal channel amplifiers to compensate for drift associated with temperature changes, battery decay, component aging, etc., in each channel is accomplished by means of a unique auto zero feature which between signal pulses holds a zero correction voltage on an integrating capacitor coupled to the corresponding channel amplifier output. Pseudo-continuous outputs for each channel are achieved by pulsed sample-and-hold circuits which are updated at the pulsed operation rate. The sample-and-hold outputs are multiplexed into an FM/FM transmitter for transmission to an FM receiver station for demultiplexing and storage in separate channel recorders.

  3. Proof-of-concept demonstration of a miniaturized three-channel multiresolution imaging system

    NASA Astrophysics Data System (ADS)

    Belay, Gebirie Y.; Ottevaere, Heidi; Meuret, Youri; Vervaeke, Michael; Van Erps, Jürgen; Thienpont, Hugo

    2014-05-01

    Multichannel imaging systems have several potential applications such as multimedia, surveillance, medical imaging and machine vision, and have therefore been a hot research topic in recent years. Such imaging systems, inspired by natural compound eyes, have many channels, each covering only a portion of the total field-of-view of the system. As a result, these systems provide a wide field-of-view (FOV) while having a small volume and a low weight. Different approaches have been employed to realize a multichannel imaging system. We demonstrated that the different channels of the imaging system can be designed in such a way that they can have each different imaging properties (angular resolution, FOV, focal length). Using optical ray-tracing software (CODE V), we have designed a miniaturized multiresolution imaging system that contains three channels each consisting of four aspherical lens surfaces fabricated from PMMA material through ultra-precision diamond tooling. The first channel possesses the largest angular resolution (0.0096°) and narrowest FOV (7°), whereas the third channel has the widest FOV (80°) and the smallest angular resolution (0.078°). The second channel has intermediate properties. Such a multiresolution capability allows different image processing algorithms to be implemented on the different segments of an image sensor. This paper presents the experimental proof-of-concept demonstration of the imaging system using a commercial CMOS sensor and gives an in-depth analysis of the obtained results. Experimental images captured with the three channels are compared with the corresponding simulated images. The experimental MTF of the channels have also been calculated from the captured images of a slanted edge target test. This multichannel multiresolution approach opens the opportunity for low-cost compact imaging systems that can be equipped with smart imaging capabilities.

  4. HYDRAULICS OF THE ATCHAFALAYA BASIN MAIN CHANNEL SYSTEM: CONSIDERATIONS FROM A MULTIUSE MANAGEMENT STANDPOINT

    EPA Science Inventory

    The report examines the relationships among hydraulic elements in the Atchafalaya Basin floodway system in terms of discharge regime, sediment load, channel form and size, flood control, water surface slope, bank elevation, overbank capacity, dredging requirements, and spoil disp...

  5. Single-channel color information security system using LU decomposition in gyrator transform domains

    NASA Astrophysics Data System (ADS)

    Abuturab, Muhammad Rafiq

    2014-07-01

    A novel single-channel color information security system based on LU decomposition in gyrator transform domains is proposed. The original color image to be encoded is separated into its red, green and blue channels. They are modulated by corresponding random phase functions and then independently Fourier transformed. The transformed images of red and green channels are multiplied and then inverse Fourier transformed. The resulting image is phase- and amplitude truncated to obtain an encrypted image and an asymmetric decryption key, respectively. The encrypted image is multiplied by transformed image of blue channel and then performed LU decomposition. Finally, L and U parts are individually gyrator transformed at different transformation angles, which can be assigned to two different authorized users. The proposed single-channel encryption system is more compact than conventional three-channel encryption systems. Additionally, the ciphertexts are not color images but they are gray images which have obscure properties. The presented LU form is asymmetric. The two transformation angles of GT, three decryption keys for three channels and one asymmetric decryption key significantly improve the security and robustness of the proposed method. The encryption system can be realized digitally or optically. Numerical simulations demonstrate the feasibility and effectiveness of the suggested algorithms.

  6. An error recovery technique for a satellite channel assignment system with distributed control

    NASA Astrophysics Data System (ADS)

    Emstad, P. J.; Halaas, A.

    1980-09-01

    A distributed control system for a set of earth stations sharing satellite communication channels is studied. The stations communicate by messages which may be corrupted by errors. A sufficient set of message types are defined to allow stations to enter and leave the system, to arbitrate for communication channels, and to recover from error situations. The error processes assumed are of a transient nature, mainly existing on the interstation control channels. The signaling communication protocols are informally described in a Pascal-like language. The protocols are simulated in Simula and are found to work correctly in all cases studied.

  7. A slow-speed multiple-channel analog-to-digital data logging system

    NASA Technical Reports Server (NTRS)

    Lloyd, T. C.; Flaherty, B. J.

    1973-01-01

    The system was developed to record from one up to a maximum of sixteen channels of analog data onto magnetic tape. Each analog channel of data can be sampled at rates of 1, 2, 6, 12, or 60 times per minute. The system is divided into three subunits: a digital clock, an incremental magnetic tape recorder, and a sequential converter. The interfacing requirements of these subunits are presented.

  8. Low-mobility channel tracking for MIMO-OFDM communication systems

    NASA Astrophysics Data System (ADS)

    Pagadarai, Srikanth; Wyglinski, Alexander M.; Anderson, Christopher R.

    2013-12-01

    It is now well understood that by exploiting the available additional spatial dimensions, multiple-input multiple-output (MIMO) communication systems provide capacity gains, compared to a single-input single-output systems without increasing the overall transmit power or requiring additional bandwidth. However, these large capacity gains are feasible only when the perfect knowledge of the channel is available to the receiver. Consequently, when the channel knowledge is imperfect, as is common in practical settings, the impact of the achievable capacity needs to be evaluated. In this study, we begin with a general MIMO framework at the outset and specialize it to the case of orthogonal frequency division multiplexing (OFDM) systems by decoupling channel estimation from data detection. Cyclic-prefixed OFDM systems have attracted widespread interest due to several appealing characteristics not least of which is the fact that a single-tap frequency-domain equalizer per subcarrier is sufficient due to the circulant structure of the resulting channel matrix. We consider a low-mobility wireless channel which exhibits inter-block channel variations and apply Kalman tracking when MIMO-OFDM communication is performed. Furthermore, we consider the signal transmission to contain a stream of training and information symbols followed by information symbols alone. By relying on predicted channel states when training symbols are absent, we aim to understand how the improvements in channel capacity are affected by imperfect channel knowledge. We show that the Kalman recursion procedure can be simplified by the optimal minimum mean square error training design. Using the simplified recursion, we derive capacity upper and lower bounds to evaluate the performance of the system.

  9. 47 CFR 22.1007 - Channels for offshore radiotelephone systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... East to longitude W.94°00′ on the West and from the 4.8 kilometer (3 mile) limit along the Gulf of....350 491.350 488.175 491.175 488.375 491.375 488.200 491.200 488.400 491.400 (2) These channels may be.... Central Subscriber Central Subscriber 489.000 492.000 489.200 492.200 489.025 492.025 489.225 492.225...

  10. 47 CFR 22.1007 - Channels for offshore radiotelephone systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... East to longitude W.94°00′ on the West and from the 4.8 kilometer (3 mile) limit along the Gulf of....350 491.350 488.175 491.175 488.375 491.375 488.200 491.200 488.400 491.400 (2) These channels may be.... Central Subscriber Central Subscriber 489.000 492.000 489.200 492.200 489.025 492.025 489.225 492.225...

  11. Multi-channel holographic birfurcative neural network system for real-time adaptive EOS data analysis

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang; Diep, J.; Huang, K.

    1991-01-01

    Viewgraphs on multi-channel holographic bifurcative neural network system for real-time adaptive Earth Observing System (EOS) data analysis are presented. The objective is to research and develop an optical bifurcating neuromorphic pattern recognition system for making optical data array comparisons and to evaluate the use of the system for EOS data classification, reduction, analysis, and other applications.

  12. Design of a communications system for multiple telemetry data channels operating simultaneously with a coherent turn-around ranging channel

    NASA Technical Reports Server (NTRS)

    Nguyen, Tien M.; Hinedi, Sami M.; Gevargiz, John M.

    1991-01-01

    This paper presents a simple technique to design a phase-modulated residual carrier communications link for optimum performance. The emphasis is on two data channels which are operated simultaneously with a ranging signal. The data channels employ PCM/PM and PCM/PSK/PM modulation schemes for high and low data rate channels, respectively. The technique proposed here selects the optimum (1) subcarrier frequency to minimize the interference between the two data channels, and (2) modulation indices for optimum balance of power between the two telemetry data channels and the coherent turn around ranging channel. The selected set of optimum modulation indices will allow for the specified bit error rate (BER) degradations in the two data channels. Although this technique is proposed to optimize the performance degradation for two data channels, generalizations can be made for more than two data channels.

  13. Integrated source and channel encoded digital communication system design study

    NASA Technical Reports Server (NTRS)

    Huth, G. K.; Udalov, S.

    1974-01-01

    This study investigated the configuration and integration of a wideband communication system with a Ku-band rendezvous radar system. The goal of the study was to provide as much commonality between the two systems as possible. The antenna design was described with the only change being the requirement for dual polarization (linear for the radar system and circular for the communication system).

  14. The channels of Mars

    NASA Technical Reports Server (NTRS)

    Baker, Victor R.

    1988-01-01

    The geomorphology of Mars is discussed, focusing on the Martian channels. The great flood channels of Mars, the processes of channel erosion, and dendritic channel networks, are examined. The topography of the Channeled Scabland region of the northwestern U.S. is described and compared to the Martian channels. The importance of water in the evolution of the channel systems is considered.

  15. Cloud and Aerosol Lidar Channel Design and Performance of the Geoscience Laser Altimeter System on the ICESat Mission

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Abshire, James B.; Krainak, Michael A.; Spinhirne, James D.; Palm, Steve S.; Lancaster, Redgie S.; Allan, Graham R.

    2004-01-01

    The design of the 532 and 1064nm wavelength atmosphere lidar channels of the Geoscience Laser Altimeter System on the ICESat spacecraft is described. The lidar channel performance per on orbit measurements data will be presented.

  16. System design for a million channel digital spectrum analyzer /MCSA/. [of bandpass filtering in SETI receivers

    NASA Technical Reports Server (NTRS)

    Peterson, A.; Narasimha, M.; Narayan, S.

    1980-01-01

    The system design of a wideband (8 MHz) million-channel digital spectrum analyzer for use with a SETI receiver is presented. The analyzer makes use of a digital bandpass filter bank for transforming the wideband input signal into a specified number (120) of uniform narrowband output channels by the use of a Fourier transform digital processor combined with a prototype digital weighting network (finite impulse response filter). The output is then processed separately by 120 microprocessor-based discrete Fourier transform computers, each producing 8190 output channels of approximately 8 Hz bandwidth by the use of an 8190-point prime factor algorithm.

  17. Coupled-rearrangement-channels calculation of the three-body system under the absorbing boundary condition

    NASA Astrophysics Data System (ADS)

    Iwasaki, M.; Otani, R.; Ito, M.; Kamimura, M.

    2016-05-01

    We formulate the method of the absorbing boundary condition (ABC) in the coupled-rearrangement-channels variational method (CRCMV) for the three-body problem. In the present study, we handle the simple three-boson system, and the absorbing potential is introduced in the Jacobi coordinate in the individual rearrangement channels. The resonance parameters and the strength of the monopole breakup are compared with the complex scaling method (CSM). We have found that the CRCVM + ABC method nicely works in the threebody problem with the rearrangement channels.

  18. Channel estimation algorithm for interference suppression in IMDD-OQAM-OFDM transmission systems

    NASA Astrophysics Data System (ADS)

    Zhang, Lu; Xiao, Shilin; Bi, Meihua; Liu, Ling; Zhou, Zhao

    2016-04-01

    In this paper, we investigate the intrinsic interference caused by intra-symbol data and channel noise in the intensity-modulation direct-detection OQAM-OFDM (IMDD-OQAM-OFDM) system by theoretical derivation. Based on the analysis, we proposed and experimentally demonstrated a channel estimation algorithm with the combination of IAM-C and frequency-averaging method to combat the effect of these noises. Experimental results show that compared to the common channel estimation algorithms, our algorithm can greatly reduce the error vector magnitude (EVM) and achieve ~1.5 dB sensitivity improvement.

  19. RBF multiuser detector with channel estimation capability in a synchronous MC-CDMA system.

    PubMed

    Ko, K; Choi, S; Kang, C; Hong, D

    2001-01-01

    The authors propose a multiuser detector with channel estimation capability using a radial basis function (RBF) network in a synchronous multicarrier-code division multiple access (MC-CDMA) system. The authors propose to connect an RBF network to the frequency domain to effectively utilize the frequency diversity. Simulations were performed over frequency-selective and multi-path fading channels. These simulations confirmed that the proposed receiver can be used both for the channel estimation and as a multi-user receiver, thus permitting an increase in the number of active users. PMID:18249987

  20. Note: Experimental observation of nano-channel pattern in light sheet laser interference nanolithography system

    NASA Astrophysics Data System (ADS)

    Mohan, Kavya; Mondal, Partha Pratim

    2016-06-01

    We experimentally observed nano-channel-like pattern in a light-sheet based interference nanolithography system. The optical system created nano-channel-like patterned illumination. Coherent counter-propagating light sheets are made to interfere at and near geometrical focus along the propagation z-axis. This results in the formation of nano-channel-like pattern (of size ≈ 300 nm and inter-channel periodicity of ≈337.5 nm) inside the sample due to constructive and destructive interference. In addition, the technique has the ability to generate large area patterning using larger light-sheets. Exciting applications are in the broad field of nanotechnology (nano-electronics and nano-fluidics).

  1. The multi-channel laser focusing transceiver system and analysis of the image quality

    NASA Astrophysics Data System (ADS)

    Sui, Xin; Sun, Hongri; Yang, Kun; Qu, Zhou; Zhang, Bo; Cui, Yihan

    2015-10-01

    This paper has investigated and designed a multi-channel laser focusing transceiver system based on the combination of the laser technology, the space technology and the modern photoelectric detection technology which has the feather of wide wave band, non-chromatic aberration and high quality of image quality etc. The system could be synchronized and can change the distance of detection in a particular direction and obtain the image of atmospheric echo signals at different distances. In this paper we established a multi-channel and variable range laser focusing transceiver system that consists of a single-channel laser focusing transmitter system and a dual-channel receiving telescope system. The three channels of the system depend on the same reference axis. We propose a new method that is capable to improve the laser focusing transceiver system performance. The method is implemented by using parabolic reflector design in the primary and secondary mirror of the variable range laser focusing transmitter system, dual-channel off-axis design in the receiver system and simultaneous imaging design in the different regions of the same CCD target surface of the subsequent imaging system. The detection by two channels using off-axis design would be convenient for computing follow up information. On the base of theoretical basis of the reflective double mirror system and the theory Gaussian beam propagation, this paper calculates the actual converging sot size of the transmitter system and analyzes the wavefront aberration the defocus incidence. The oblique incidence will introduce the certain astigmatism and a small amount of coma and the defocus incidence will produce the certain coma and a small amount of spherical aberration and astigmatism. Finally, an experimental multi-channel laser focusing transceiver system was established and the image quality of the transceiver system on the base of wavefront aberrations, the spot diagram and the MTF curve of some fields is

  2. Complexity analysis and control in joint channel protection system for wireless video communications

    NASA Astrophysics Data System (ADS)

    Jin, Xin; Zhu, Guangxi

    2007-02-01

    In wireless communications, channel coding and error control are essential to protect the video data from wireless interference. The power it consumed, which is determined by the protection method it used, will directly affect the system performance especially on the decoding side. In this paper, a channel coding and error control system, called joint channel protection (JCP) system here, is proposed as an improvement of the hybrid automatic repeat request (HARQ) system to integrate the complexity controllability. The complexity models of the encoder and decoder are established based on theoretical analysis and statistical data retrieval using the time complexity concept, and the relative variation in the computational complexity is carefully studied to provide a proportional variation reference for complexity control. Based on the models, strategies are designed to control the system complexity by adjusting the packet length, iterative decoding times and retransmission ratio according to the decoding quality and complexity level.

  3. Channel direction information probing for multi-antenna cognitive radio system

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Villardi, Gabriel Porto; Kojima, Fumihide; Yano, Hiroyuki

    2015-12-01

    This work studies the problem of channel direction information (CDI) probing for multi-antenna cognitive radio system. The CDI of the channel from the secondary transmitter (ST) to primary receiver (PR) is elementary information in designing the beamforming at the ST for mitigating the interference to the PR. However, lacking the explicit cooperation between primary and secondary systems, the CDI has to be acquired by probing at the ST, which is challenging. To solve this, we consider the line of sight (LoS) channel between the ST and the PR, and propose one CDI probing scheme for the ST. Specifically, the ST sends two types of probing signals by beamforming towards an interested region where both the secondary receiver (SR) and the PR are located and then actively learns the hidden feedback information from the primary system to acquire the CDI. The proposed scheme has a closed-form solution, and avoids the iteration between the probing and acquisition, which is desirable for practical system. Moreover, we show that the proposed probing scheme can be extended for primary systems working under multi-access channel and broadcasting channel. Simulation results demonstrate that the proposed scheme can improve the accuracy of the acquired CDI at the ST in cognitive ratio system remarkably.

  4. Integrated source and channel encoded digital communication system design study

    NASA Technical Reports Server (NTRS)

    Alem, W. K.; Huth, G. K.; Simon, M. K.

    1978-01-01

    The particular Ku-band carrier, PN despreading, and symbol synchronization strategies, which were selected for implementation in the Ku-band transponder aboard the orbiter, were assessed and evaluated from a systems performance viewpoint, verifying that system specifications were met. A study was performed of the design and implementation of tracking techniques which are suitable for incorporation into the Orbiter Ku-band communication system. Emphasis was placed on maximizing tracking accuracy and communication system flexibility while minimizing cost, weight, and system complexity of Orbiter and ground systems hardware. The payload communication study assessed the design and performance of the forward link and return link bent-pipe relay modes for attached and detached payloads. As part of this study, a design for a forward link bent-pipe was proposed which employs a residual carrier but which is tracked by the existing Costas loop.

  5. Reduced Complexity in Antenna Selection for Polarized MIMO System with SVD for the Practical MIMO Communication Channel Environment

    NASA Astrophysics Data System (ADS)

    Sann Maw, Maung; Sasase, Iwao

    In the conventional multi-input multi-output (MIMO) communication systems, most of the antenna selection methods considered are suitable only for spatially separated uni-polarized system under Rayleigh fading channel in non-line of sight (NLOS) condition. There have a few antenna selection schemes for the cross-polarized system in LOS condition and Ricean fading channel, and no antenna selection scheme for the MIMO channel with both LOS and NLOS. In the practical MIMO channel case, influence of LOS and NLOS conditions in the channel can vary from time to time according to the channel parameters and user movement in the system. Based on these influences and channel condition, uni-polarized system may outperform a cross-polarized. Thus, we should consider this kind of practical MIMO channel environment when developing the antenna selection scheme. Moreover, no research work has been done on reducing the complexity of antenna selection for this kind of practical MIMO channel environment. In this paper, reduced complexity in antenna selection is proposed to give the higher throughput in the practical MIMO channel environment. In the proposed scheme, suitable polarized antennas are selected based on the calculation of singular value decomposition (SVD) of channel matrix and then adaptive bit loading is applied. Simulation results show that throughput of the system can be improved under the constraint of target BER and total transmit power of the MIMO system.

  6. Growing stocker channel catfish in a biofloc technology production system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biofloc technology (BFT), or mixed suspended-growth, production systems are being used more frequently worldwide for culturing various aquatic animals because of the high yields that are possible. In an outdoor BFT production system, a complex of living organisms is closely associated with particula...

  7. Multiple channel secure communication using chaotic system encoding

    SciTech Connect

    Miller, S.L.

    1996-12-31

    fA new method to encrypt signals using chaotic systems has been developed that offers benefits over conventional chaotic encryption methods. The method simultaneously encodes multiple plaintext streams using a chaotic system; a key is required to extract the plaintext from the chaotic cipertext. A working prototype demonstrates feasibility of the method by simultaneously encoding and decoding multiple audio signals using electrical circuits.

  8. Solids management in a channel catfish biofloc technology production system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biofloc technology (BFT) production systems are being used more commonly to produce high yields of fish or shrimp because very high feed rates are possible. In an outdoor BFT production system, a complex of living organisms is closely associated with particulate organic matter and is maintained in s...

  9. Channel estimation for OFDM system in atmospheric optical communication based on compressive sensing

    NASA Astrophysics Data System (ADS)

    Zhao, Qingsong; Hao, Shiqi; Geng, Hongjian; Sun, Han

    2015-10-01

    Orthogonal frequency division multiplexing (OFDM) technique applied to the atmospheric optical communication can improve data transmission rate, restrain pulse interference, and reduce effect of multipath caused by atmospheric scattering. Channel estimation, as one of the important modules in OFDM, has been investigated thoroughly and widely with great progress. In atmospheric optical communication system, channel estimation methods based on pilot are common approaches, such as traditional least-squares (LS) algorithm and minimum mean square error (MMSE) algorithm. However, sensitivity of the noise effects and high complexity of computation are shortcomings of LS algorithm and MMSE algorithm, respectively. Here, a new method based on compressive sensing is proposed to estimate the channel state information of atmospheric optical communication OFDM system, especially when the condition is closely associated with turbulence. Firstly, time-varying channel model is established under the condition of turbulence. Then, in consideration of multipath effect, sparse channel model is available for compressive sensing. And, the pilot signal is reconstructed with orthogonal matching tracking (OMP) algorithm, which is used for reconstruction. By contrast, the work of channel estimation is completed by LS algorithm as well. After that, simulations are conducted respectively in two different indexes -signal error rate (SER) and mean square error (MSE). Finally, result shows that compared with LS algorithm, the application of compressive sensing can improve the performance of SER and MSE. Theoretical analysis and simulation results show that the proposed method is reasonable and efficient.

  10. Long-term morphological response to dredging including cut-across-shoal in a tidal channel-shoal system

    NASA Astrophysics Data System (ADS)

    Wang, Yu-Hai; Wang, Chong-Hao; Tang, Li-Qun; Liu, Da-Bin; Guo, Chuan-Sheng; Liu, Chun-Jing; Zhao, Hui-Ming

    2014-12-01

    This study examines long-term channel-shoal stability in the Tieshan Bay, which is located on the southwest coast of China. A large-scale channel-shoal system has historically existed in the outer Tieshan Bay. A navigation waterway is initiated by cutting and dredging a mid-channel shoal to supply coal to a power plant on the middle coast of the Tieshan Bay. Dredging of the access channel to the Tieshan Port was conducted in two stages followed by land reclamation. It is thus of practical meaning to explore how the channel-shoal system will evolve in long term afterwards. This study uses the process-based finite-volume coastal ocean model (FVCOM) to investigate long-term (centennial) morphological evolution of the channel-shoal system. After well calibration of hydrodynamics and sediment transport, the model forecasts morphodynamic evolution in hundred years. The simulations show that continuous erosion in tidal channels and accretion over shoals and intertidal flats occur. However, the cutting and access channels will be subjected to long-term siltation. A secondary channel indicating the reorientation of the access channel will emerge, and a localized channel-ridge system at the junction of the major channels will be formed. The overall erosion/accretion pattern demonstrates the combined effect of bottom friction and advective sediment transport processes to be responsible for the channel-shoal formation. Dredging of the tidal channels will stimulate the stability of the channel-shoal pattern. It suggests that the navigation waterway should be set up following the long-term morphological evolution of the channel-shoal system at a design stage and maintenance dredging volume might thus be minimized.

  11. Winter performance of an outdoor biofloc production system for channel catfish

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the tropics, outdoor biofloc technology production systems are operated year-round. While channel catfish (Ictalurus punctatus) have been grown successfully in an outdoor biofloc production system, these studies were conducted only during the growing season and production tanks were idled for the...

  12. Quantum-Mechanical Channel of Interactions between Macroscopic Systems

    SciTech Connect

    Sargsyan, R. Sh.; Karamyana, G. G.; Gevorkyan, A. S.

    2010-05-04

    The macroscopic experimental phenomena which cannot be explained in the frames of classical concepts are described. The attempt of qualitatively understanding of observed effects based on Bohm's representation of Schroedinger equation for arbitrary system of interacting particles is presented.

  13. An extremum-seeking MHD generator channel flow control system

    SciTech Connect

    Vasil`ev, V.V.

    1995-01-01

    Progress in the development and study of new electric energy generation methods, based on direct conversion of heat energy, raises the problem of more effective use of their power characteristics. A self-optimizing control system for an object with a unimodal quality function has been developed. The system consists of the object, a divider, a band-pass filter, an averaging filter, a multiplier, a final control element, an adder, and a search signal generator.

  14. Extended Horizon Liftings for Periodic Gain Adjustments in Control Systems, and for Equalization of Communication Channels

    NASA Technical Reports Server (NTRS)

    Bayard, David S. (Inventor)

    1996-01-01

    Periodic gain adjustment in plants of irreducible order, n, or for equalization of communications channels is effected in such a way that the plant (system) appears to be minimum phase by choosing a horizon time N greater then n of liftings in periodic input and output windows Pu and Py, respectively, where N is an integer chosen to define the extent (length) of each of the windows Pu and Py, and n is the order of an irreducible input/output plant. The plant may be an electrical, mechanical or chemical system, in which case output tracking (OT) is carried out for feedback control or a communication channel, in which case input tracking (IT) is carried out. Conditions for OT are distinct from IT in terms of zero annihilation, namely for OT and of IT, where the OT conditions are intended for gain adjustments in the control system, and IT conditions are intended for equalization for communication channels.

  15. Interactive multimedia systems as communication channels in color workshops

    NASA Astrophysics Data System (ADS)

    Gaudio, Alejandra; De Ponti, Javier

    2002-06-01

    Great technological advances can help us to recover communication areas that might otherwise be lost. Media competition and visual contamination frequently appear in daily communication. A notable anonymity in human relationship has emerged as a consequence of this. Educational establishments receive an overflowing number of students. Schools and students are overwhelmed by this situation. Teachers don't know their students and students usually don't know their own classmates, with all the consequences that this implies. In front of this inadequate structure of educational institutions, technology has improved the possibilities of instant answers and the dialogue between teachers and students; the unilateral exposition pronounced by teachers in front of the anonymous mass finds an alternative in multimedia systems. The present work describes Interactive Multimedia System's utilization for teaching the chromatic circle as a system of color organization. The proposed method intends to devise a theoretical and conceptual frame and its production for multimedia systems oriented to elaborate, represent, store, interact with and access to knowledge Its relevance comes from the potential contribution to build up knowledge systems that value cultural codes and at the same time make creative and motivating interactive experiences. This work concerns the realization and understanding of the chromatic circle, selection of different color systems, logical strategies for playing and studying theory and multimedia. Levels of visualization: theory, practice, developing skills, works and evaluation. Levels to study: teaching chromatic circle, multimedia supports, quality, application and linking screens, help, theory, etc; without losing the interdisciplinary nature of the work, specialist participation, and Multimedia Systems in the steps of its realization.

  16. A 64-channel ultra-low power system-on-chip for local field and action potentials recording

    NASA Astrophysics Data System (ADS)

    Rodríguez-Pérez, Alberto; Delgado-Restituto, Manuel; Darie, Angela; Soto-Sánchez, Cristina; Fernández-Jover, Eduardo; Rodríguez-Vázquez, Ángel

    2015-06-01

    This paper reports an integrated 64-channel neural recording sensor. Neural signals are acquired, filtered, digitized and compressed in the channels. Additionally, each channel implements an auto-calibration mechanism which configures the transfer characteristics of the recording site. The system has two transmission modes; in one case the information captured by the channels is sent as uncompressed raw data; in the other, feature vectors extracted from the detected neural spikes are released. Data streams coming from the channels are serialized by an embedded digital processor. Experimental results, including in vivo measurements, show that the power consumption of the complete system is lower than 330μW.

  17. Innovative RF Design Unites Benefits of Multiplexed and Multi-Channel System

    NASA Astrophysics Data System (ADS)

    Mavrič, Uroš

    2004-11-01

    The main advantages of the implemented innovative RF design are reproducibility, accuracy, low measurement uncertainty, and compact design. They were achieved by implementing the direct RF sampling and the completely new, patent pending technological approach of quasi-crossbar multiplexing and associated measurement method. The innovative quasi-crossbar switch matrix unites the benefits of both the multi-channel and the multiplexed system and at the same time compensates the disadvantages of the two. We achieve reproducibility and good "beam vs. current" dependence, which are multiplexed system characteristics and, using a multi-channel approach, we ensure a broader band of operation.

  18. Selective excitation, relaxation, and energy channeling in molecular systems

    SciTech Connect

    Rhodes, W.C.

    1993-08-01

    Research involves theoretical studies of response, relaxation, and correlated motion in time-dependent behavior of large molecular systems ranging from polyatomic molecules to protein molecules in their natural environment. Underlying theme is subsystem modulation dynamics. Main idea is that quantum mechanical correlations between components of a system develop with time, playing a major role in determining the balance between coherent and dissipative forces. Central theme is interplay of coherence and dissipation in determining the nature of dynamic structuring and energy flow in molecular transformation mechanisms. Subsystem equations of motion are being developed to show how nonlinear, dissipative dynamics of a particular subsystem arise from correlated interactions with the rest of the system (substituent groups, solvent, lattice modes, etc.); one consequence is resonance structures and networks. Quantum dynamics and thermodynamics are being applied to understand control and energy transfer mechanisms in biological functions of protein molecules; these mechanisms are both global and local. Besides the above theory, the research deals with phenomenological aspects of molecular systems.

  19. Single layer, multi-channel band-gear system for rotary joint

    NASA Technical Reports Server (NTRS)

    Kong, Kin Yuen (Inventor)

    1998-01-01

    A multi-channel band-gear system for a rotary joint has a ring gear assembly with a conducting ring band in electrical contact with corresponding conducting bands of a set of intermediary planetary gears, which in turn are in electrical contact with a conducting sun band of a sun gear assembly. The ring band is formed with a plurality of conducting segments which are electrically insulated from each other and positioned angularly in a circumferential direction of the ring gear, such that separate electrical power/signal channels are formed across the rotary joint. In a preferred embodiment having continuously connected channels, the ring band has four conducting segments at 90.degree. intervals, the sun band has two conducting segments at 180.degree. intervals, and three planetary bands are in rolling electrical contact at 120.degree. intervals between the ring band segments and the sun band segments, forming two continuously connected channels in a single layer of the band-gear system. Multiple sets of ring gear, planetary gear, and sun gear assemblies may be used in a stacked configuration in a single axial layer to further increase the number of channels provided through the band-gear system.

  20. Mix and match: Investigating heteromeric and heterotypic gap junction channels in model systems and native tissues

    PubMed Central

    Koval, Michael; Molina, Samuel A.; Burt, Janis M.

    2014-01-01

    This review is based in part on a roundtable discussion session: “Physiological roles for heterotypic/heteromeric channels” at the 2013 International Gap Junction Conference (IGJC 2013) in Charleston, South Carolina. It is well recognized that multiple connexins can specifically co-assemble to form mixed gap junction channels with unique properties as a means to regulate intercellular communication. Compatibility determinants for both heteromeric and heterotypic gap junction channel formation have been identified and associated with specific connexin amino acid motifs. Hetero-oligomerization is also a regulated process; differences in connexin quality control and monomer stability are likely to play integral roles to control interactions between compatible connexins. Gap junctions in oligodendrocyte:astrocyte communication and in the cardiovascular system have emerged as key systems where heterotypic and heteromeric channels have unique physiologic roles. There are several methodologies to study heteromeric and heterotypic channels that are best applied to either heterologous expression systems, native tissues or both. There remains a need to use and develop different experimental approaches in order to understand the prevalence and roles for mixed gap junction channels in human physiology. PMID:24561196

  1. Channel Equalization and Phase Estimation for Reduced-Guard-Interval CO-OFDM Systems

    NASA Astrophysics Data System (ADS)

    Zhuge, Qunbi

    Reduced-guard-interval (RGI) coherent optical (CO) orthogonal frequency-division multiplexing (OFDM) is a potential candidate for next generation 100G beyond optical transports, attributed to its advantages such as high spectral efficiency and high tolerance to optical channel impairments. First of all, we review the coherent optical systems with an emphasis on CO-OFDM systems as well as the optical channel impairments and the general digital signal processing techniques to combat them. This work focuses on the channel equalization and phase estimation of RGI CO-OFDM systems. We first propose a novel equalization scheme based on the equalization structure of RGI CO-OFDM to reduce the cyclic prefix overhead to zero. Then we show that intra-channel nonlinearities should be considered when designing the training symbols for channel estimation. Afterwards, we propose and analyze the phenomenon of dispersion-enhanced phase noise (DEPN) caused by the interaction between the laser phase noise and the chromatic dispersion in RGI CO-OFDM transmissions. DEPN induces a non-negligible performance degradation and limits the tolerant laser linewidth. However, it can be compensated by the grouped maximum-likelihood phase estimation proposed in this work.

  2. Indoor positioning system using WLAN channel estimates as fingerprints for mobile devices

    NASA Astrophysics Data System (ADS)

    Schmidt, Erick; Akopian, David

    2015-03-01

    With the growing integration of location based services (LBS) such as GPS in mobile devices, indoor position systems (IPS) have become an important role for research. There are several IPS methods such as AOA, TOA, TDOA, which use trilateration for indoor location estimation but are generally based on line-of-sight. Other methods rely on classification such as fingerprinting which uses WLAN indoor signals. This paper re-examines the classical WLAN fingerprinting accuracy which uses received signal strength (RSS) measurements by introducing channel estimates for improvements in the classification of indoor locations. The purpose of this paper is to improve existing classification algorithms used in fingerprinting by introducing channel estimates when there are a low number of APs available. The channel impulse response, or in this case the channel estimation from the receiver, should characterize a complex indoor area which usually has multipath, thus providing a unique signature for each location which proves useful for better pattern recognition. In this experiment, channel estimates are extracted from a Software-Defined Radio (SDR) environment, thus exploiting the benefits of SDR from a NI-USRP model and LabVIEW software. Measurements are taken from a known building, and several scenarios with one and two access points (APs) are used in this experiment. Also, three granularities in distance between locations are analyzed. A Support Vector Machine (SVM) is used as the algorithm for pattern recognition of different locations based on the samples taken from RSS and channel estimation coefficients.

  3. Multi-channel data acquisition system with absolute time synchronization

    NASA Astrophysics Data System (ADS)

    Włodarczyk, Przemysław; Pustelny, Szymon; Budker, Dmitry; Lipiński, Marcin

    2014-11-01

    We present a low-cost, stand-alone global-time-synchronized data acquisition system. Our prototype allows recording up to four analog signals with a 16-bit resolution in variable ranges and a maximum sampling rate of 1000 S/s. The system simultaneously acquires readouts of external sensors e.g. magnetometer or thermometer. A complete data set, including a header containing timestamp, is stored on a Secure Digital (SD) card or transmitted to a computer using Universal Serial Bus (USB). The estimated time accuracy of the data acquisition is better than ±200 ns. The device is intended for use in a global network of optical magnetometers (the Global Network of Optical Magnetometers for Exotic physics - GNOME), which aims to search for signals heralding physics beyond the Standard Model, that can be generated by ordinary spin coupling to exotic particles or anomalous spin interactions.

  4. Development of a 64 channel ultrasonic high frequency linear array imaging system.

    PubMed

    Hu, ChangHong; Zhang, Lequan; Cannata, Jonathan M; Yen, Jesse; Shung, K Kirk

    2011-12-01

    In order to improve the lateral resolution and extend the field of view of a previously reported 48 element 30 MHz ultrasound linear array and 16-channel digital imaging system, the development of a 256 element 30 MHz linear array and an ultrasound imaging system with increased channel count has been undertaken. This paper reports the design and testing of a 64 channel digital imaging system which consists of an analog front-end pulser/receiver, 64 channels of Time-Gain Compensation (TGC), 64 channels of high-speed digitizer as well as a beamformer. A Personal Computer (PC) is used as the user interface to display real-time images. This system is designed as a platform for the purpose of testing the performance of high frequency linear arrays that have been developed in house. Therefore conventional approaches were taken it its implementation. Flexibility and ease of use are of primary concern whereas consideration of cost-effectiveness and novelty in design are only secondary. Even so, there are many issues at higher frequencies but do not exist at lower frequencies need to be solved. The system provides 64 channels of excitation pulsers while receiving simultaneously at a 20-120 MHz sampling rate to 12-bits. The digitized data from all channels are first fed through Field Programmable Gate Arrays (FPGAs), and then stored in memories. These raw data are accessed by the beamforming processor to re-build the image or to be downloaded to the PC for further processing. The beamformer that applies delays to the echoes of each channel is implemented with the strategy that combines coarse (8.3 ns) and fine delays (2 ns). The coarse delays are integer multiples of the sampling clock rate and are achieved by controlling the write enable pin of the First-In-First-Out (FIFO) memory to obtain valid beamforming data. The fine delays are accomplished with interpolation filters. This system is capable of achieving a maximum frame rate of 50 frames per second. Wire phantom images

  5. Polarization Drift Channel Model for Coherent Fibre-Optic Systems

    PubMed Central

    Czegledi, Cristian B.; Karlsson, Magnus; Agrell, Erik; Johannisson, Pontus

    2016-01-01

    A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts, emulating a random walk on the Poincaré sphere, which has been successfully verified using experimental data. The model is described in the Jones, Stokes and real four-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future systems, where polarization-multiplexed transmission and sophisticated digital signal processing will be natural parts. The proposed polarization drift model is the first of its kind as prior work either models polarization drift as a deterministic process or focuses on polarization-mode dispersion in systems where the state of polarization does not affect the receiver performance. We expect the model to be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue. PMID:26905596

  6. Polarization Drift Channel Model for Coherent Fibre-Optic Systems.

    PubMed

    Czegledi, Cristian B; Karlsson, Magnus; Agrell, Erik; Johannisson, Pontus

    2016-01-01

    A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts, emulating a random walk on the Poincaré sphere, which has been successfully verified using experimental data. The model is described in the Jones, Stokes and real four-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future systems, where polarization-multiplexed transmission and sophisticated digital signal processing will be natural parts. The proposed polarization drift model is the first of its kind as prior work either models polarization drift as a deterministic process or focuses on polarization-mode dispersion in systems where the state of polarization does not affect the receiver performance. We expect the model to be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue. PMID:26905596

  7. Polarization Drift Channel Model for Coherent Fibre-Optic Systems

    NASA Astrophysics Data System (ADS)

    Czegledi, Cristian B.; Karlsson, Magnus; Agrell, Erik; Johannisson, Pontus

    2016-02-01

    A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts, emulating a random walk on the Poincaré sphere, which has been successfully verified using experimental data. The model is described in the Jones, Stokes and real four-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future systems, where polarization-multiplexed transmission and sophisticated digital signal processing will be natural parts. The proposed polarization drift model is the first of its kind as prior work either models polarization drift as a deterministic process or focuses on polarization-mode dispersion in systems where the state of polarization does not affect the receiver performance. We expect the model to be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue.

  8. Pairwise Quantum Discord for a Symmetric Multi-Qubit System in Different Types of Noisy Channels

    NASA Astrophysics Data System (ADS)

    Guo, You-Neng; Zeng, Ke; Wang, Guo-You

    2016-06-01

    We study the pairwise quantum discord (QD) for a symmetric multi-qubit system in different types of noisy channels, such as phase-flip, amplitude damping, phase-damping, and depolarizing channels. Using the QD and geometric quantum discord (GMQD) to quantify quantum correlations, some analytical and numerical results are presented. The results show that, the QD dynamics is strongly related to the number of spin particles N as well as the initial parameter 𝜃 of the one-axis twisting collective state. With the number of spin particles N increasing, the amount of the QD increases. However, when the amount of the QD arrives at a stable maximal value, the QD is independence of the number of spin particles N increasing. The behavior of the QD is symmetrical during a period 0 ≤ 𝜃 ≤ 2 π. Moreover, we compare the QD dynamics with the GMQD for a symmetric multi-qubit system in different types of noisy channels.

  9. Channel correlation of transmit diversity FSO systems with partially coherent optical beams

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoyang; Yao, Mingwu; Yi, Xiang; Liu, Zengji; Qiu, Zhiliang

    2015-01-01

    Spatial diversity, including transmit diversity, has been proven to be a promising technique to mitigate turbulence-induced signal fading. However, due to the limitation of size in compact FSO (free-space optical) terminals, the transmit antennas cannot always be separated far enough from each other, resulting in increased channel correlation and deteriorated diversity performance. In this paper, we focus on the channel correlation statistics of transmit diversity FSO systems with two transmit beams. Specifically, we consider partially coherent optical beams, which reduce scintillation over fully coherent optical beams. We perform theoretical analysis and obtain some interesting numerical results, such as the degree of channel correlation which changed mainly with source correlation radius from 0.001 to 0.1 m. These results can be helpful for designing transmit diversity FSO systems with partially coherent beams.

  10. A Four Channel Beam Current Monitor Data Acquisition System Using Embedded Processors

    SciTech Connect

    Wheat, Jr., Robert Mitchell; Dalmas, Dale A.; Dale, Gregory E.

    2015-08-11

    Data acquisition from multiple beam current monitors is required for electron accelerator production of Mo-99. A two channel system capable of recording data from two beam current monitors has been developed, is currently in use, and is discussed below. The development of a cost-effective method of extending this system to more than two channels and integrating of these measurements into an accelerator control system is the main focus of this report. Data from these current monitors is digitized, processed, and stored by a digital data acquisition system. Limitations and drawbacks with the currently deployed digital data acquisition system have been identified as have been potential solutions, or at least improvements, to these problems. This report will discuss and document the efforts we've made in improving the flexibility and lowering the cost of the data acquisition system while maintaining the minimum requirements.

  11. Correlation channel modeling for practical Slepian-Wolf distributed video compression system using irregular LDPC codes

    NASA Astrophysics Data System (ADS)

    Li, Li; Hu, Xiao; Zeng, Rui

    2007-11-01

    The development of practical distributed video coding schemes is based on the consequence of information-theoretic bounds established in the 1970s by Slepian and Wolf for distributed lossless coding, and by Wyner and Ziv for lossy coding with decoder side information. In distributed video compression application, it is hard to accurately describe the non-stationary behavior of the virtual correlation channel between X and side information Y although it plays a very important role in overall system performance. In this paper, we implement a practical Slepian-Wolf asymmetric distributed video compression system using irregular LDPC codes. Moreover, based on exploiting the dependencies of previously decode bit planes from video frame X and side information Y, we present improvement schemes to divide different reliable regions. Our simulation results show improving schemes of exploiting the dependencies between previously decoded bit planes can get better overall encoding rate performance as BER approach zero. We also show, compared with BSC model, BC channel model is more suitable for distributed video compression scenario because of the non-stationary properties of the virtual correlation channel and adaptive detecting channel model parameters from previously adjacent decoded bit planes can provide more accurately initial belief messages from channel at LDPC decoder.

  12. Channel aware HARQ scheme based on LDPC codes for land mobile satellite communication system

    NASA Astrophysics Data System (ADS)

    Yang, Yongli; Zhu, Guangxi; Wang, Desheng; Wu, Lifen

    2007-11-01

    In this paper, a channel aware HARQ (CA-HARQ) scheme based on data punctured rate compatible LDPC (DP-LDPC) codes, which might satisfy the demand for bandwidth and rate in land mobile communication system, is proposed. The scheme is based on type II HARQ technique cooperated with a DP- LDPC code. In the proposed scheme, the effective rate of the LDPC code is adapted according to the channel quality information (CQI) estimated at the receiver, so as to decrease the redundancy when the channel is good and vice versa, the retransmitted blocks are combined with the previous information transmitted to achieve high probability of successful decoding. In this paper, we use a 2-bit CQI feedback scheme. Simulation results, which based on a land mobile satellite channel, show that the proposed channel aware H-ARQ scheme based on DP-LDPC codes improved the throughput by 0.4dB at low SNR compared to a pure DP-LDPC type II HARQ, and it can also be an effective solution to compensate rain attenuation and multipath fading in land mobile satellite systems.

  13. Adaptive Resource Allocation for the PB/MC-CDMA System in Frequency Selective Fading Channels

    NASA Astrophysics Data System (ADS)

    Lee, Kyujin; Lee, Kyesan

    We propose Adaptive Resource Allocation for the Partial Block MC-CDMA (ARA-PB/MC-CDMA) system. The ARA-PB/MC-CDMA system aims to improve total throughput performance and frequency efficiency across various channel conditions. It adaptively changes the number of blocks to improve the throughput performance and frequency efficiency according to the Signal to Interference Ratio (SIR). Therefore, the proposed system supports various Quality of Service (QoS) requirements for various SIR values.

  14. Integrated source and channel encoded digital communication system design study. [for space shuttles

    NASA Technical Reports Server (NTRS)

    Huth, G. K.

    1976-01-01

    The results of several studies Space Shuttle communication system are summarized. These tasks can be divided into the following categories: (1) phase multiplexing for two- and three-channel data transmission, (2) effects of phase noise on the performance of coherent communication links, (3) analysis of command system performance, (4) error correcting code tradeoffs, (5) signal detection and angular search procedure for the shuttle Ku-band communication system, and (6) false lock performance of Costas loop receivers.

  15. Multi-Channel Data Acquisition System for Nuclear Pulse Processing

    SciTech Connect

    Myjak, Mitchell J.; Ma, Ding; Robinson, Dirk J.; La Rue, George S.

    2009-11-13

    We have developed a compact, inexpensive electronics package that can digitize pulse-mode or current-mode data from 32 detector outputs in parallel. The electronics package consists of two circuit boards: a custom acquisition board and an off-the-shelf processing board. The acquisition board features a custom-designed integrated circuit that contains an array of charge-to-pulse-width converters. The processing board contains a field programmable gate array that digitizes the pulse widths, performs event discrimination, constructs energy histograms, and executes any user-defined software. Together, the two boards cost around $1000. The module can transfer data to a computer or operate entirely as a standalone system. The design achieves 0.20% nonlinearity and 0.18% FWHM precision at full scale. However, the overall performance could be improved with some modifications to the integrated circuit.

  16. Integrated source and channel encoded digital communication system design study

    NASA Technical Reports Server (NTRS)

    Udalov, S.; Huth, G. K.

    1977-01-01

    The analysis of the forward link signal structure for the shuttle orbiter Ku-band communication system was carried out, based on the assumptions of a 3.03 Mcps PN code. It is shown that acquisition requirements for the forward link can be met at the acquisition threshold C/N0 sub 0 value of about 60 dB-Hz, which corresponds to a bit error rate (BER) of about 0.001. It is also shown that the tracking threshold for the forward link is at about 57 dB-Hz. The analysis of the bent pipe concept for the orbiter was carried out, along with the comparative analysis of the empirical data. The complexity of the analytical approach warrants further investigation to reconcile the empirical and theoretical results. Techniques for incorporating a text and graphics capability into the forward link data stream are considered and a baseline configuration is described.

  17. Evaluation of Various Feeding Regimens in A Multiple-Batch Cropping System of Channel Catfish Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A four-year pond study was conducted to compare gross production, feed conversion, processing yield, and body composition of channel catfish Ictalurus punctatus fed once daily or every other day to satiation, or # 110 kg/ha per day in a multiple-batch cropping system. The greatest amount of feed fed...

  18. Case Management Agency Systems of Administering Long-Term Care: Evidence from the Channeling Demonstration.

    ERIC Educational Resources Information Center

    Kemper, Peter

    1990-01-01

    Examines what was learned from channeling demonstration about potential of case management agency systems for administering home care benefits. Considers both advantages (substitution of lower cost for higher cost services, negotiation of lower prices for services, quality assurance) and disadvantages (difficulty controlling participation rates,…

  19. Channel Estimation and ISI/ICI Cancellation for MIMO-OFDM Systems with Insufficient Cyclic Prefix

    NASA Astrophysics Data System (ADS)

    Chiu, Yi-Jen; Chen, Chien-Sheng; Chang, Ting-Wei

    In multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems, the multipath components whose delays exceed cyclic prefix (CP) cause inter-symbol interference (ISI) and inter-carrier interference (ICI), which may degrade system performance severely. In this paper, we propose a joint channel estimation and ISI/ICI cancellation scheme in which a limited CP is used in a trade-off against high-rate performance in MIMO-OFDM systems. A channel estimation scheme based on the criterion of Expectation-Maximization (EM) algorithm can be proposed through the use of a training symbol. The EM algorithm uses an iterative procedure to estimate channel parameters and can estimate channel impulse response (CIR) accurately enough to mitigate ISI/ICI influences. Through the accurate CIR estimation, an efficient method has been developed to counteract ISI/ICI influences in signal detection in the case where the inserted CP length is less than the CIR length. Simulation results show that the proposed method can significantly enhance the overall MIMO-OFDM system performance after only a few iterations.

  20. Identifying and Quantifying Ecological Changes in Channel Bank Systems in a Small California Agricultural Watershed

    NASA Astrophysics Data System (ADS)

    Florsheim, J. L.; Nichols, A. L.; Ustin, S.; Lay, M.

    2011-12-01

    episodic floods, with likely responses dependent on complex interactions between the landscape-scale legacy of past landuse, such as channel incision, flood magnitude and duration, and current landuses that may include grazing or restoration. Floods may cause bank erosion, expose tree roots, undercut trees, modify bars, or incise the channel bed. In a resilient watershed, the spatial heterogeneity in these processes creates and maintains dynamic bank and aquatic ecosystems and biodiversity. In contrast, in watersheds where channels are incised and human activities have denuded riparian vegetation, the system may have crossed a threshold such that a flood causes a regime shift between resiliency and degradation of channel bank habitat.

  1. The importance of flow in the Mozambique Channel to seasonality in the Greater Agulhas Current System

    NASA Astrophysics Data System (ADS)

    Biastoch, A.; Reason, C. J. C.; Lutjeharms, J. R. E.; Boebel, O.

    The temporal variability of the greater Agulhas Current system has important climatological consequences. Some recent results have suggested that this variability contains a large seasonal component, due to changes in the circulation at latitudes poleward of Madagascar only. A model simulation shows that the contribution of Tropical Surface Water to Agulhas Current waters, via the Mozambique Channel, also has a distinct seasonal characteristic that is brought about by the seasonal wind stress over the tropical Indian Ocean. This simulated flow through the Channel contributes substantially to the seasonality of the Agulhas Current. This model result is shown to be not inconsistent with available hydrographic observations.

  2. A 128-channel picoammeter system and its application on charged particle beam current distribution measurements

    SciTech Connect

    Yu, Deyang Liu, Junliang; Xue, Yingli; Zhang, Mingwu; Cai, Xiaohong; Hu, Jianjun; Dong, Jinmei; Li, Xin

    2015-11-15

    A 128-channel picoammeter system is constructed based on instrumentation amplifiers. Taking advantage of a high electric potential and narrow bandwidth in DC energetic charged beam measurements, a current resolution better than 5 fA can be achieved. Two sets of 128-channel strip electrodes are implemented on printed circuit boards and are employed for ion and electron beam current distribution measurements. Tests with 60 keV O{sup 3+} ions and 2 keV electrons show that it can provide exact boundaries when a positive charged particle beam current distribution is measured.

  3. Development of superconducting contacts for the CRESST II 66-channel superconducting quantum interference device readout system.

    PubMed

    Majorovits, B; Henry, S; Kraus, H

    2007-07-01

    The CRESST experiment is designed to search for weakly interacting massive particle dark matter with cryogenic detectors. CRESST II will use up to 33 CaWO(4) crystals with a total mass of approximately 10 kg. These many detectors require a readout system based on 66-channel superconducting quantum interference devices (SQUIDs). In this article we report on the development of a modular superconducting connector for the 66-channel SQUID readout circuit. We show that the technique developed reliably produces superconducting contacts. PMID:17672757

  4. Development of superconducting contacts for the CRESST II 66-channel superconducting quantum interference device readout system

    SciTech Connect

    Majorovits, B.; Henry, S.; Kraus, H.

    2007-07-15

    The CRESST experiment is designed to search for weakly interacting massive particle dark matter with cryogenic detectors. CRESST II will use up to 33 CaWO{sub 4} crystals with a total mass of {approx}10 kg. These many detectors require a readout system based on 66-channel superconducting quantum interference devices (SQUIDs). In this article we report on the development of a modular superconducting connector for the 66-channel SQUID readout circuit. We show that the technique developed reliably produces superconducting contacts.

  5. A 128-channel picoammeter system and its application on charged particle beam current distribution measurements

    NASA Astrophysics Data System (ADS)

    Yu, Deyang; Liu, Junliang; Xue, Yingli; Zhang, Mingwu; Cai, Xiaohong; Hu, Jianjun; Dong, Jinmei; Li, Xin

    2015-11-01

    A 128-channel picoammeter system is constructed based on instrumentation amplifiers. Taking advantage of a high electric potential and narrow bandwidth in DC energetic charged beam measurements, a current resolution better than 5 fA can be achieved. Two sets of 128-channel strip electrodes are implemented on printed circuit boards and are employed for ion and electron beam current distribution measurements. Tests with 60 keV O3+ ions and 2 keV electrons show that it can provide exact boundaries when a positive charged particle beam current distribution is measured.

  6. Quantum interference of stored dual-channel spin-wave excitations in a single tripod system

    SciTech Connect

    Wang Hai; Li Shujing; Xu Zhongxiao; Zhao Xingbo; Zhang Lijun; Li Jiahua; Wu Yuelong; Xie Changde; Peng Kunchi; Xiao Min

    2011-04-15

    We present an experimental demonstration of dual-channel memory in a single tripod atomic system. The total readout signal exhibits either constructive or destructive interference when the dual-channel spin-wave excitations (SWEs) are retrieved by two reading beams with a controllable relative phase. When the two reading beams have opposite phases, the SWEs will remain in the medium, which can be retrieved later with two in-phase reading beams. Such a phase-sensitive storage and retrieval scheme can be used to measure and control the relative phase between the two SWEs in the memory medium, which may find applications in quantum-information processing.

  7. BER Performance for Downlink MC-CDMA Systems over Rician Fading Channels

    NASA Astrophysics Data System (ADS)

    Hou, Zhihua; Dubey, Vimal K.

    2005-12-01

    We consider downlink multicarrier code-division multiple-access (MC-CDMA) systems using binary phase-shift keying (BPSK) modulation scheme and maximal ratio combining (MRC) in frequency-selective Rician fading channels. A time-domain method to obtain bit error rate (BER) by calculating moment generating function (MGF) of the decision variable for a tapped-delay-line channel model is proposed. This method does not require any assumption regarding the statistical or spectral distribution of multiple access interference (MAI), and it is also not necessary to assume that the fading encountered by the subcarriers is independent of each other. The analytical formula is also verified by simulations.

  8. Novel control channel quality improvement in satellite communication systems employing high coding gain FEC

    NASA Astrophysics Data System (ADS)

    Morikura, Masahiro; Kubota, Shuji; Enomoto, Kiyoshi; Kato, Shuzo

    The authors propose a novel control channel quality improvement scheme for satellite communication systems using a majority decision method over convolutional coding and Viterbi decoding channels. To improve majority decision performance, which is degraded by burst errors due to Viterbi decoding in conventional serial transmission methods, a parallel transmission method is proposed. The performance of the parallel and serial transmission methods has been analyzed, and experiments have been carried out using rate-1/2 convolutional encoding and Viterbi decoding (constraint length 4 and 7). It is shown that the parallel transmission method has about 1010 times lower block-error performance at Pe = 1 x 10-4 than the conventional method.

  9. Channel migration patterns and related sequences in some alluvial fan systems

    NASA Astrophysics Data System (ADS)

    Viseras, C.; Fernández, J.

    1994-01-01

    The pendular displacement of a channel system, consisting of an area of higher channel density (trunk channel zone) on both sides of which channel density progressively decreases (secondary channel zone), can, under favourable subsidence conditions, lead to the development of alluvial fans. Characteristic sequences are found in these fans, depending on their position in the sedimentary body. A marginal position in the fan is thus recognized by the superposition of fining and thinning upwards (FTU) cycles, the upper part of which is made up of important thicknesses of overbank fines, all the backsets of bars dipping in the same direction (towards the centre of the cone). On the other hand, a central position is characterized by a higher number of FTU cycles, which are incomplete due to erosion of the upper parts (corresponding to the higher concentration of overbank fines), and the backsets in each cycle dip alternately in opposite directions. The displacement of the channel system in a constant direction may be caused by the preferential accumulation of bars on one of the banks of the channel. The change in migratory direction giving rise to the pendular movement is caused by the trunk channel reaching the basin margin or the sedimentation area of an adjoining fan. Palaeogeographic reconstructions of fans using this technique contribute to the analysis of ancient basins: small-radius fans with a high sweep angle (A S) are characteristic of basin margins subjected to a low sediment supply/subsidence ratio (S S /S B), whereas large-radius fans with a low A S characterize periods with a high S S /S B ratio on the basin margin. This model can be applied in economic geology studies, as the location of an ancient cone permits delimitation of the axial strip (with a higher proportion of coarse, highly porous, channelled facies) and the marginal sectors (where thick layers of less porous overbank fines are intercalated). We here present the example of the alluvial fans in

  10. SFO compensation by pilot-aided channel estimation for real-time DDO-OFDM system

    NASA Astrophysics Data System (ADS)

    Deng, Rui; He, Jing; Chen, Ming; Chen, Lin

    2015-11-01

    In this paper, we experimentally demonstrated a pilot-aided and linear interpolated channel estimation technique in the real-time direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) system using a cost-effective directly modulated laser (DML). It has been verified that the pilot-aided and linear interpolated channel estimation technique can help to compensate the sampling frequency offset (SFO) effect. The experimental results show that, based on the pilot-aided and linear interpolated channel estimation technique, even at a SFO of 170 ppm, a 16-QAM-OFDM signal can be successfully transmitted over 100-km SSMF under the hard-decision forward-error-correction (HD-FEC) threshold with a bit error rate of 3.8×10-3. And the effect of up to ~25 ppm SFO can be negligible.

  11. Sodium channel polypeptides in central nervous systems of various insects identified with site directed antibodies.

    PubMed

    Gordon, D; Moskowitz, H; Zlotkin, E

    1990-07-01

    Immunoprecipitation, radiophosphorylation and SDS-PAGE autoradiography enable the characterization of sodium channel polypeptides in the central nervous system of insects belonging to four phylogenetically distinct orders: grasshoppers, cockroaches, flies and moth larvae. It has been shown that the insect sodium channels: (1) Are recognized by the previously described (Gordon et al. (1988) Biochemistry 27, 7032-7038) site directed antibodies corresponding to a highly conserved segment linking the homologous domains III and IV in the vertebrate sodium channel alpha subunits. (2) Serve as substrates for phosphorylation by cAMP-dependent protein kinase. (3) Are devoid of disulfide linkage to smaller subunits unlike sodium channels in vertebrate brain. (4) Are glycoproteins as shown in the grasshopper by the decrease of apparent molecular weight following endoglycosidase F treatment and specific binding to the lectins concanavalin A and wheat germ agglutinin. (5) Reveal a diversity with regard to their (a) apparent molecular masses which range from 240 to 280 kDa and (b) V8 proteinase digestion phosphopeptides indicating either differences in the positioning of the enzymatic cleavage and/or phosphorylation sites. These results provide the first evidence for structural diversity of sodium channel subtypes among various insect orders and are compared to their mammalian counterparts. PMID:2165810

  12. Peptide-gated ion channels and the simple nervous system of Hydra.

    PubMed

    Gründer, Stefan; Assmann, Marc

    2015-02-15

    Neurons either use electrical or chemical synapses to communicate with each other. Transmitters at chemical synapses are either small molecules or neuropeptides. After binding to their receptors, transmitters elicit postsynaptic potentials, which can either be fast and transient or slow and longer lasting, depending on the type of receptor. Fast transient potentials are mediated by ionotropic receptors and slow long-lasting potentials by metabotropic receptors. Transmitters and receptors are well studied for animals with a complex nervous system such as vertebrates and insects, but much less is known for animals with a simple nervous system like Cnidaria. As cnidarians arose early in animal evolution, nervous systems might have first evolved within this group and the study of neurotransmission in cnidarians might reveal an ancient mechanism of neuronal communication. The simple nervous system of the cnidarian Hydra extensively uses neuropeptides and, recently, we cloned and functionally characterized an ion channel that is directly activated by neuropeptides of the Hydra nervous system. These results demonstrate the existence of peptide-gated ion channels in Hydra, suggesting they mediate fast transmission in its nervous system. As related channels are also present in the genomes of the cnidarian Nematostella, of placozoans and of ctenophores, it should be considered that the early nervous systems of cnidarians and ctenophores have co-opted neuropeptides for fast transmission at chemical synapses. PMID:25696818

  13. The LES of the channel flow in a non aligned system of coordinates

    NASA Astrophysics Data System (ADS)

    Germano, Massimo; Abbà, Antonella

    2010-11-01

    The plane channel flow continues to be a very important test case for the verification and the validation of LES. In the channel flow test there is a privileged direction, usually one reference axis is oriented along the stream and the size of the computational box is increased in the streamwise direction in order to capture correctly the dominant turbulent structures and to produce a fully developed flow. All that is peculiar of this particular test, and in this paper we will investigate the sensitivity of the channel test to the particular alignment of the coordinate system with the mean flow. In a non aligned system of coordinates there is no privileged direction, there are two components of the forcing term, the mean pressure gradient, and the homogeneities of the Reynolds stresses are destroyed. In our paper we simulate the channel flow in a rotated system of coordinates, and we compare the results with the stream aligned data. We think that this test could evidence the flexibility of different LES codes and LES subgrid models to simulate the turbulent flow and to capture the correct statistical values in non aligned conditions. The first preliminary results are slightly contradictory: the resolved Reynolds stresses seem degraded while the mean flow is better predicted. The dynamic anisotropic subgrid model of Abbà, Cercignani and Valdettaro seems well fitted to represent correctly the large scales in non aligned conditions.

  14. Channel estimation in DFT-based offset-QAM OFDM systems.

    PubMed

    Zhao, Jian

    2014-10-20

    Offset quadrature amplitude modulation (offset-QAM) orthogonal frequency division multiplexing (OFDM) exhibits enhanced net data rates compared to conventional OFDM, and reduced complexity compared to Nyquist FDM (N-FDM). However, channel estimation in discrete-Fourier-transform (DFT) based offset-QAM OFDM is different from that in conventional OFDM and requires particular study. In this paper, we derive a closed-form expression for the demultiplexed signal in DFT-based offset-QAM systems and show that although the residual crosstalk is orthogonal to the decoded signal, its existence degrades the channel estimation performance when the conventional least-square method is applied. We propose and investigate four channel estimation algorithms for offset-QAM OFDM that vary in terms of performance, complexity, and tolerance to system parameters. It is theoretically and experimentally shown that simple channel estimation can be realized in offset-QAM OFDM with the achieved performance close to the theoretical limit. This, together with the existing advantages over conventional OFDM and N-FDM, makes this technology very promising for optical communication systems. PMID:25401598

  15. Centralized Routing and Scheduling Using Multi-Channel System Single Transceiver in 802.16d

    NASA Astrophysics Data System (ADS)

    Al-Hemyari, A.; Noordin, N. K.; Ng, Chee Kyun; Ismail, A.; Khatun, S.

    This paper proposes a cross-layer optimized strategy that reduces the effect of interferences from neighboring nodes within a mesh networks. This cross-layer design relies on the routing information in network layer and the scheduling table in medium access control (MAC) layer. A proposed routing algorithm in network layer is exploited to find the best route for all subscriber stations (SS). Also, a proposed centralized scheduling algorithm in MAC layer is exploited to assign a time slot for each possible node transmission. The cross-layer optimized strategy is using multi-channel single transceiver and single channel single transceiver systems for WiMAX mesh networks (WMNs). Each node in WMN has a transceiver that can be tuned to any available channel for eliminating the secondary interference. Among the considered parameters in the performance analysis are interference from the neighboring nodes, hop count to the base station (BS), number of children per node, slot reuse, load balancing, quality of services (QoS), and node identifier (ID). Results show that the proposed algorithms significantly improve the system performance in terms of length of scheduling, channel utilization ratio (CUR), system throughput, and average end to end transmission delay.

  16. Stability assessment of QKD procedures in commercial quantum cryptography systems versus quality of dark channel

    NASA Astrophysics Data System (ADS)

    Jacak, Monika; Melniczuk, Damian; Jacak, Janusz; Jóźwiak, Ireneusz; Gruber, Jacek; Jóźwiak, Piotr

    2015-02-01

    In order to assess the susceptibility of the quantum key distribution (QKD) systems to the hacking attack including simultaneous and frequent system self-decalibrations, we analyze the stability of the QKD transmission organized in two commercially available systems. The first one employs non-entangled photons as flying qubits in the dark quantum channel for communication whereas the second one utilizes the entangled photon pairs to secretly share the cryptographic key. Applying standard methods of the statistical data analysis to the characteristic indicators of the quality of the QKD communication (the raw key exchange rate [RKER] and the quantum bit error rate [QBER]), we have estimated the pace of the self-decalibration of both systems and the repeatability rate in the case of controlled worsening of the dark channel quality.

  17. A Three-Channel DC SQUID System Using Time-Domain Multiplexing

    NASA Astrophysics Data System (ADS)

    Korn, Matthias; Mueck, Michael; Mugford, Chas; Kycia, Jan

    2004-03-01

    Conventional multichannel SQUID systems require SQUID readout electronics for each channel, as well as many wires connecting the individual SQUIDs and feedback coils to the room temperature electronics. We have studied a time domain multiplexed readout scheme which requires only a single SQUID readout which is successively switched between all SQUIDs. By connecting all SQUIDs and all feedback coils in series, the system requires only a few wires between SQUIDs and room temperature readout.

  18. Channel coding and data compression system considerations for efficient communication of planetary imaging data

    NASA Technical Reports Server (NTRS)

    Rice, R. F.

    1974-01-01

    End-to-end system considerations involving channel coding and data compression are reported which could drastically improve the efficiency in communicating pictorial information from future planetary spacecraft. In addition to presenting new and potentially significant system considerations, this report attempts to fill a need for a comprehensive tutorial which makes much of this very subject accessible to readers whose disciplines lie outside of communication theory.

  19. The Martain drainage system and the origin of valley networks and fretted channels

    NASA Astrophysics Data System (ADS)

    Carr, Michael H.

    1995-04-01

    Outflow channels provide strong evidence for abundant water near the Martian surface and an extensive groundwater system. Collapse of the surface into some channels suggests massive subsurface erosion and/or solution in addition to erosion by flow across the surface. Flat floors, steep walls, longitudinal striae and ridges, downstream deflection of striae from channel walls, and lack of river channels suggest that fretted channels form dominantly by mass wasting. A two-stage process is proposed. In the first stage, extension of valleys heads is favored by seepage of groundwater into debris shed from slopes. The debris moves downstream, aided by interstitial groundwater at the base of the debris, possibly with high pore pressures. In the second stage, because of climate change or a lower heat flow, groundwater can no longer seep into the debris flows in the valleys, their movement almost stops, and more viscous ice-lubricated debris aprons form. Almost all uplands at elevations greater than +1 km are dissected by valley networks, although the drainage densities are orders of magnitude less than is typical for the Earth. The valley networks resemble terrestrial river systems in planimetric shape, but U-shaped and rectangular-shaped cross sections, levee- like peripheral ridges, median ridges, patterns of branching and rejoining, and flat floors without river channels suggest that the networks may not be true analogs to terrestrial river valleys. It is proposed that they, like the fretted channels, formed mainly by mass wasting, aided by groundwater seepage into the mass-wasted debris. Movements of only millimeters to centimeters per year are needed to explain the channel lengths. Most valley formation ceased early at low latitudes because of progressive dehydration of the near surface, the result of sublimation of water and/or drainage of groundwater to regions of lower elevations. Valley formation persisted to later dates where aided by steep slopes, as on crater

  20. A parallel finite element simulator for ion transport through three-dimensional ion channel systems.

    PubMed

    Tu, Bin; Chen, Minxin; Xie, Yan; Zhang, Linbo; Eisenberg, Bob; Lu, Benzhuo

    2013-09-15

    A parallel finite element simulator, ichannel, is developed for ion transport through three-dimensional ion channel systems that consist of protein and membrane. The coordinates of heavy atoms of the protein are taken from the Protein Data Bank and the membrane is represented as a slab. The simulator contains two components: a parallel adaptive finite element solver for a set of Poisson-Nernst-Planck (PNP) equations that describe the electrodiffusion process of ion transport, and a mesh generation tool chain for ion channel systems, which is an essential component for the finite element computations. The finite element method has advantages in modeling irregular geometries and complex boundary conditions. We have built a tool chain to get the surface and volume mesh for ion channel systems, which consists of a set of mesh generation tools. The adaptive finite element solver in our simulator is implemented using the parallel adaptive finite element package Parallel Hierarchical Grid (PHG) developed by one of the authors, which provides the capability of doing large scale parallel computations with high parallel efficiency and the flexibility of choosing high order elements to achieve high order accuracy. The simulator is applied to a real transmembrane protein, the gramicidin A (gA) channel protein, to calculate the electrostatic potential, ion concentrations and I - V curve, with which both primitive and transformed PNP equations are studied and their numerical performances are compared. To further validate the method, we also apply the simulator to two other ion channel systems, the voltage dependent anion channel (VDAC) and α-Hemolysin (α-HL). The simulation results agree well with Brownian dynamics (BD) simulation results and experimental results. Moreover, because ionic finite size effects can be included in PNP model now, we also perform simulations using a size-modified PNP (SMPNP) model on VDAC and α-HL. It is shown that the size effects in SMPNP can

  1. Characterization of a mini-channel heat exchanger for a heat pump system

    NASA Astrophysics Data System (ADS)

    Arteconi, A.; Giuliani, G.; Tartuferi, M.; Polonara, F.

    2014-04-01

    In this paper a mini-channel aluminum heat exchanger used in a reversible heat pump is presented. Mini-channel finned heat exchangers are getting more and more interest for refrigeration systems, especially when compactness and low refrigerant charge are desired. Purpose of this paper was to characterize the mini-channel heat exchanger used as evaporator in terms of heat transfer performance and to study the refrigerant distribution in the manifold. The heat exchanger characterization was performed experimentally by means of a test rig built up for this purpose. It is composed of an air-to-air heat pump, air channels for the external and internal air circulation arranged in a closed loop, measurement sensors and an acquisition system. The overall heat transfer capacity was assessed. Moreover, in order to characterize the flow field of the refrigerant in the manifold of the heat exchanger, a numerical investigation of the fluid flow by means of CFD was performed. It was meant to evaluate the goodness of the present design and to identify possible solutions for the future improvement of the manifold design.

  2. Integrated optofluidic-microfluidic twin channels: toward diverse application of lab-on-a-chip systems

    PubMed Central

    Lv, Chao; Xia, Hong; Guan, Wei; Sun, Yun-Lu; Tian, Zhen-Nan; Jiang, Tong; Wang, Ying-Shuai; Zhang, Yong-Lai; Chen, Qi-Dai; Ariga, Katsuhiko; Yu, Yu-De; Sun, Hong-Bo

    2016-01-01

    Optofluidics, which integrates microfluidics and micro-optical components, is crucial for optical sensing, fluorescence analysis, and cell detection. However, the realization of an integrated system from optofluidic manipulation and a microfluidic channel is often hampered by the lack of a universal substrate for achieving monolithic integration. In this study, we report on an integrated optofluidic-microfluidic twin channels chip fabricated by one-time exposure photolithography, in which the twin microchannels on both surfaces of the substrate were exactly aligned in the vertical direction. The twin microchannels can be controlled independently, meaning that fluids could flow through both microchannels simultaneously without interfering with each other. As representative examples, a tunable hydrogel microlens was integrated into the optofluidic channel by femtosecond laser direct writing, which responds to the salt solution concentration and could be used to detect the microstructure at different depths. The integration of such optofluidic and microfluidic channels provides an opportunity to apply optofluidic detection practically and may lead to great promise for the integration and miniaturization of Lab-on-a-Chip systems. PMID:26823292

  3. Integrated optofluidic-microfluidic twin channels: toward diverse application of lab-on-a-chip systems.

    PubMed

    Lv, Chao; Xia, Hong; Guan, Wei; Sun, Yun-Lu; Tian, Zhen-Nan; Jiang, Tong; Wang, Ying-Shuai; Zhang, Yong-Lai; Chen, Qi-Dai; Ariga, Katsuhiko; Yu, Yu-De; Sun, Hong-Bo

    2016-01-01

    Optofluidics, which integrates microfluidics and micro-optical components, is crucial for optical sensing, fluorescence analysis, and cell detection. However, the realization of an integrated system from optofluidic manipulation and a microfluidic channel is often hampered by the lack of a universal substrate for achieving monolithic integration. In this study, we report on an integrated optofluidic-microfluidic twin channels chip fabricated by one-time exposure photolithography, in which the twin microchannels on both surfaces of the substrate were exactly aligned in the vertical direction. The twin microchannels can be controlled independently, meaning that fluids could flow through both microchannels simultaneously without interfering with each other. As representative examples, a tunable hydrogel microlens was integrated into the optofluidic channel by femtosecond laser direct writing, which responds to the salt solution concentration and could be used to detect the microstructure at different depths. The integration of such optofluidic and microfluidic channels provides an opportunity to apply optofluidic detection practically and may lead to great promise for the integration and miniaturization of Lab-on-a-Chip systems. PMID:26823292

  4. Integrated optofluidic-microfluidic twin channels: toward diverse application of lab-on-a-chip systems

    NASA Astrophysics Data System (ADS)

    Lv, Chao; Xia, Hong; Guan, Wei; Sun, Yun-Lu; Tian, Zhen-Nan; Jiang, Tong; Wang, Ying-Shuai; Zhang, Yong-Lai; Chen, Qi-Dai; Ariga, Katsuhiko; Yu, Yu-De; Sun, Hong-Bo

    2016-01-01

    Optofluidics, which integrates microfluidics and micro-optical components, is crucial for optical sensing, fluorescence analysis, and cell detection. However, the realization of an integrated system from optofluidic manipulation and a microfluidic channel is often hampered by the lack of a universal substrate for achieving monolithic integration. In this study, we report on an integrated optofluidic-microfluidic twin channels chip fabricated by one-time exposure photolithography, in which the twin microchannels on both surfaces of the substrate were exactly aligned in the vertical direction. The twin microchannels can be controlled independently, meaning that fluids could flow through both microchannels simultaneously without interfering with each other. As representative examples, a tunable hydrogel microlens was integrated into the optofluidic channel by femtosecond laser direct writing, which responds to the salt solution concentration and could be used to detect the microstructure at different depths. The integration of such optofluidic and microfluidic channels provides an opportunity to apply optofluidic detection practically and may lead to great promise for the integration and miniaturization of Lab-on-a-Chip systems.

  5. Compressed sensing theory-based channel estimation for optical orthogonal frequency division multiplexing communication system

    NASA Astrophysics Data System (ADS)

    Zhao, Hui; Li, Minghui; Wang, Ruyan; Liu, Yuanni; Song, Daiping

    2014-09-01

    Due to the spare multipath property of the channel, a channel estimation method, which is based on partial superimposed training sequence and compressed sensing theory, is proposed for line of sight optical orthogonal frequency division multiplexing communication systems. First, a continuous training sequence is added at variable power ratio to the cyclic prefix of orthogonal frequency division multiplexing symbols at the transmitter prior to transmission. Then the observation matrix of compressed sensing theory is structured by the use of the training symbols at receiver. Finally, channel state information is estimated using sparse signal reconstruction algorithm. Compared to traditional training sequences, the proposed partial superimposed training sequence not only improves the spectral efficiency, but also reduces the influence to information symbols. In addition, compared with classical least squares and linear minimum mean square error methods, the proposed compressed sensing theory based channel estimation method can improve both the estimation accuracy and the system performance. Simulation results are given to demonstrate the performance of the proposed method.

  6. Expression of K2P channels in sensory and motor neurons of the autonomic nervous system.

    PubMed

    Cadaveira-Mosquera, Alba; Pérez, Montse; Reboreda, Antonio; Rivas-Ramírez, Paula; Fernández-Fernández, Diego; Lamas, J Antonio

    2012-09-01

    Several types of neurons within the central and peripheral somatic nervous system express two-pore-domain potassium (K2P) channels, providing them with resting potassium conductances. We demonstrate that these channels are also expressed in the autonomic nervous system where they might be important modulators of neuronal excitability. We observed strong mRNA expression of members of the TRESK and TREK subfamilies in both the mouse superior cervical ganglion (mSCG) and the mouse nodose ganglion (mNG). Motor mSCG neurons strongly expressed mRNA transcripts for TRESK and TREK-2 subunits, whereas TASK-1 and TASK-2 subunits were only moderately expressed, with only few or very few transcripts for TREK-1 and TRAAK (TRESK ≈ TREK-2 > TASK-2 ≈ TASK-1 > TREK-1 > TRAAK). Similarly, the TRESK and TREK-1 subunits were the most strongly expressed in sensorial mNG neurons, while TASK-1 and TASK-2 mRNAs were moderately expressed, and fewer TREK-2 and TRAAK transcripts were detected (TRESK ≈ TREK-1 > TASK-1 ≈ TASK-2 > TREK-2 > TRAAK). Moreover, cell-attached single-channel recordings showed a major contribution of TRESK and TREK-1 channels in mNG. As the level of TRESK mRNA expression was not statistically different between the ganglia analysed, the distinct expression of TREK-1 and TREK-2 subunits was the main difference observed between these structures. Our results strongly suggest that TRESK and TREK channels are important modulators of the sensorial and motor information flowing through the autonomic nervous system, probably exerting a strong influence on vagal reflexes. PMID:22544515

  7. TRPV1 channel as a target for cancer therapy using CNT-based drug delivery systems.

    PubMed

    Ortega-Guerrero, Andres; Espinosa-Duran, John M; Velasco-Medina, Jaime

    2016-07-01

    Carbon nanotubes are being considered for the design of drug delivery systems (DDSs) due to their capacity to internalize molecules and control their release. However, for cellular uptake of drugs, this approach requires an active translocation pathway or a channel to transport the drug into the cell. To address this issue, it is suggested to use TRPV1 ion channels as a potential target for drug release by nano-DDSs since these channels are overexpressed in cancer cells and allow the permeation of large cationic molecules. Considering these facts, this work presents three studies using molecular dynamics simulations of a human TRPV1 (hTRPV1) channel built here. The purpose of these simulations is to study the interaction between a single-wall carbon nanotube (SWCNT) and hTRPV1, and the diffusion of doxorubicin (DOX) across hTRPV1 and across a POPC lipid membrane. The first study shows an attractive potential between the SWCNT surface and hTRPV1, tilting the adsorbed SWCNT. The second study shows low diffusion probability of DOX across the open hTRPV1 due to a high free energy barrier. Although, the potential energy between DOX and hTRPV1 reveals an attractive interaction while DOX is inside hTRPV1. These results suggest that if the channel is dilated, then DOX diffusion could occur. The third study shows a lower free energy barrier for DOX across the lipid membrane than for DOX across hTRPV1. Taking into account the results obtained, it is feasible to design novel nano-DDSs based on SWCNTs to accomplish controlled drug release into cells using as translocation pathway, the hTRPV1 ion channel. PMID:26872481

  8. The formation and maintenance of single-thread tie channels entering floodplain lakes: observations from three diverse river systems

    SciTech Connect

    Rowland, Joel C; Dietrich, William E; Day, Geoff; Parker, Gary

    2009-01-01

    Tie channels connect rivers to floodplain lakes on many lowland rivers and thereby play a central role in floodplain sedimentology and ecology, yet they are generally unrecognized and little studied. here we report the results of field studies focused on tie channel origin and morphodynamics in three contrasting systems: the Middle Fly River, Papua New Guinea, the Lower Mississippi River, and Birch Creek in Alaska. Across these river systems, tie channels vary by an order of magnitude in size but exhibit the same characteristic morphology and appear to develop and evolve by a similar set of processes. In all three systems, the channels are characterized by a narrow, leveed single-thread morphology with maximum width approximately one tenth the width of the mainstem river. The channels typically have a V shaped cross-section, unlike most fluvial channels. These channels develop as lakes become isolated from the river by sedimentation. Narrowing of the connection between river and lake causes a sediment-laden jet to develop. Levees develop along the margins of the jet leading to channel emergence and eventual levee aggradation to the height of the mainstem levees. Bi-directional flow in these channels is common. Outflows from the lake scour sediment and prevent channel blockage. We propose that channel geometry and size are then controlled by a dynamic balance between channel narrowing by suspended sediment deposition and incision and widening by mass failure of banks during outflows. Tie channels are laterally stable and may convey flow for hundreds to a few thousand of years.

  9. HCN1 Channels Enhance Rod System Responsivity in the Retina under Conditions of Light Exposure

    PubMed Central

    Sothilingam, Vithiyanjali; Michalakis, Stylianos; Garcia Garrido, Marina; Biel, Martin

    2016-01-01

    Purpose Vision originates in rods and cones at the outer retina. Already at these early stages, diverse processing schemes shape and enhance image information to permit perception over a wide range of lighting conditions. In this work, we address the role of hyperpolarization-activated and cyclic nucleotide-gated channels 1 (HCN1) in rod photoreceptors for the enhancement of rod system responsivity under conditions of light exposure. Methods To isolate HCN1 channel actions in rod system responses, we generated double mutant mice by crossbreeding Hcn1-/- mice with Cnga3-/- mice in which cones are non-functional. Retinal function in the resulting Hcn1-/- Cnga3-/- animals was followed by means of electroretinography (ERG) up to the age of four month. Retinal imaging via scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) was also performed to exclude potential morphological alterations. Results This study on Hcn1-/- Cnga3-/- mutant mice complements our previous work on HCN1 channel function in the retina. We show here in a functional rod-only setting that rod responses following bright light exposure terminate without the counteraction of HCN channels much later than normal. The resulting sustained signal elevation does saturate the retinal network due to an intensity-dependent reduction in the dynamic range. In addition, the lack of rapid adaptational feedback modulation of rod photoreceptor output via HCN1 in this double mutant limits the ability to follow repetitive (flicker) stimuli, particularly under mesopic conditions. Conclusions This work corroborates the hypothesis that, in the absence of HCN1-mediated feedback, the amplitude of rod signals remains at high levels for a prolonged period of time, leading to saturation of the retinal pathways. Our results demonstrate the importance of HCN1 channels for regular vision. PMID:26807953

  10. Geostationary Operational Environmental Satellite Imager infrared channel-to-channel co-registration characterization algorithm and its implementation in the ground system

    NASA Astrophysics Data System (ADS)

    Li, Zhenping; Grotenhuis, Michael; Wu, Xiangqian; Schmit, Timothy J.; Schmidt, Chris; Schreiner, Anthony J.; Nelson, James P.; Yu, Fangfang; Bysal, Hyre

    2014-01-01

    Channel-to-channel co-registration is an important performance metric for the Geostationary Operational Environmental Satellite (GOES) Imager, and large co-registration errors can have a significant impact on the reliability of derived products that rely on combinations of multiple infrared (IR) channels. Affected products include the cloud mask, fog and fire detection. This is especially the case for GOES-13, in which the co-registration error between channels 2 (3.9 μm) and 4 (10.7 μm) can be as large as 1 pixel (or ˜4 km) in the east-west direction. The GOES Imager IR channel-to-channel co-registration characterization (GII4C) algorithm is presented, which allows a systematic calculation of the co-registration error between GOES IR channel image pairs. The procedure for determining the co-registration error as a function of time is presented. The algorithm characterizes the co-registration error between corresponding images from two channels by spatially transforming one image using the fast Fourier transformation resampling algorithm and determining the distance of the transformation that yields the maximum correlation in brightness temperature. The GII4C algorithm is an area-based approach which does not depend on a fixed set of control points that may be impacted by the presence of clouds. In fact, clouds are a feature that enhances the correlations. The results presented show very large correlations over the majority of Earth-viewing pixels, with stable algorithm results. Verification of the algorithm output is discussed, and a global spatial-spectral gradient asymmetry parameter is defined. The results show that the spatial-spectral gradient asymmetry is strongly correlated to the co-registration error and can be an effective global metric for the quality of the channel-to-channel co-registration characterization algorithm. Implementation of the algorithm in the GOES ground system is presented. This includes an offline component to determine the time

  11. Episodic Channels: Effects of Regulation on Non-Equilibrium River Systems in California (Invited)

    NASA Astrophysics Data System (ADS)

    Kondolf, G. M.; Minear, J. T.

    2010-12-01

    Mediterranean-climate rivers are characterized by episodic channels, whose geomorphic work is concentrated in short, infrequent events (large floods), separated by long periods of quiescence in which the channel narrows and riparian vegetation can establish and mature, only to be disrupted by the next large disturbance. While not ‘pretty’ in conventional terms, such rivers support diverse assemblages of native species, adapted to the episodic regime. Because of the importance of irrigated agriculture in Mediterranean-climate regions, large reservoir storage projects are common, resulting in dam-induced reductions flood peaks, which have reduced dynamism in downstream channels. The result has been loss of habitat diversity and native species. A systems-level analysis of the Sacramento-San Joaquin and other rivers reveals that Q2 has commonly been reduced by 80%, sediment loads reduced, and vegetation encroached in formerly active channels. More profound have been hardening of banks and isolation of floodplains by levees. Restoration of ecological values in such rivers will require room for the river to move and flood, as well as floods sufficient to drive these processes. We identify a set of rivers with highest potential for re-activation or preservation of dynamic process in California.

  12. Method for Evaluation of Outage Probability on Random Access Channel in Mobile Communication Systems

    NASA Astrophysics Data System (ADS)

    Kollár, Martin

    2012-05-01

    In order to access the cell in all mobile communication technologies a so called random-access procedure is used. For example in GSM this is represented by sending the CHANNEL REQUEST message from Mobile Station (MS) to Base Transceiver Station (BTS) which is consequently forwarded as an CHANNEL REQUIRED message to the Base Station Controller (BSC). If the BTS decodes some noise on the Random Access Channel (RACH) as random access by mistake (so- called ‘phantom RACH') then it is a question of pure coincidence which èstablishment cause’ the BTS thinks to have recognized. A typical invalid channel access request or phantom RACH is characterized by an IMMEDIATE ASSIGNMENT procedure (assignment of an SDCCH or TCH) which is not followed by sending an ESTABLISH INDICATION from MS to BTS. In this paper a mathematical model for evaluation of the Power RACH Busy Threshold (RACHBT) in order to guaranty in advance determined outage probability on RACH is described and discussed as well. It focuses on Global System for Mobile Communications (GSM) however the obtained results can be generalized on remaining mobile technologies (ie WCDMA and LTE).

  13. Receptors, channels, and signalling in the urothelial sensory system in the bladder.

    PubMed

    Merrill, Liana; Gonzalez, Eric J; Girard, Beatrice M; Vizzard, Margaret A

    2016-04-01

    The storage and periodic elimination of urine, termed micturition, requires a complex neural control system to coordinate the activities of the urinary bladder, urethra, and urethral sphincters. At the level of the lumbosacral spinal cord, lower urinary tract reflex mechanisms are modulated by supraspinal controls with mechanosensory input from the urothelium, resulting in regulation of bladder contractile activity. The specific identity of the mechanical sensor is not yet known, but considerable interest exists in the contribution of transient receptor potential (TRP) channels to the mechanosensory functions of the urothelium. The sensory, transduction, and signalling properties of the urothelium can influence adjacent urinary bladder tissues including the suburothelial nerve plexus, interstitial cells of Cajal, and detrusor smooth muscle cells. Diverse stimuli, including those that activate TRP channels expressed by the urothelium, can influence urothelial release of chemical mediators (such as ATP). Changes to the urothelium are associated with a number of bladder pathologies that underlie urinary bladder dysfunction. Urothelial receptor and/or ion channel expression and the release of signalling molecules (such as ATP and nitric oxide) can be altered with bladder disease, neural injury, target organ inflammation, or psychogenic stress. Urothelial receptors and channels represent novel targets for potential therapies that are intended to modulate micturition function or bladder sensation. PMID:26926246

  14. Oxidation of KCNB1 K+ channels in central nervous system and beyond

    PubMed Central

    Sesti, Federico; Wu, Xilong; Liu, Shuang

    2014-01-01

    KCNB1, a voltage-gated potassium (K+) channel that conducts a major delayed rectifier current in the brain, pancreas and cardiovascular system is a key player in apoptotic programs associated with oxidative stress. As a result, this protein represents a bona fide drug target for limiting the toxic effects of oxygen radicals. Until recently the consensus view was that reactive oxygen species trigger a pro-apoptotic surge in KCNB1 current via phosphorylation and SNARE-dependent incorporation of KCNB1 channels into the plasma membrane. However, new evidence shows that KCNB1 can be modified by oxidants and that oxidized KCNB1 channels can directly activate pro-apoptotic signaling pathways. Hence, a more articulated picture of the pro-apoptotic role of KCNB1 is emerging in which the protein induces cell’s death through distinct molecular mechanisms and activation of multiple pathways. In this review article we discuss the diverse functional, toxic and protective roles that KCNB1 channels play in the major organs where they are expressed. PMID:24921000

  15. On the delay effects of different channels in Internet-based networked control systems

    NASA Astrophysics Data System (ADS)

    Zhao, Yun-Bo; Kim, Jongrae; Sun, Xi-Ming; Liu, Guo-Ping

    2013-11-01

    The sensor-to-controller and the controller-to-actuator delays in networked control systems (NCSs) are investigated for the first time with respect to their different effects on the system performance. This study starts with identifying the delay-independent and delay-dependent control laws in NCSs, and confirms that only two delay-dependent control laws can cause different delay effects in different channels. The conditions under which the different delays in different channels can cause different effects are then given for both delay-dependent control laws. The results are verified by numerical examples. Potentially, these results can be regarded as important design principles in the practical implementation of NCSs.

  16. Baseline defense system of commercial male king crab Lithodes santolla from the Beagle Channel.

    PubMed

    Schvezov, N; Lovrich, G A; Florentín, O; Romero, M C

    2015-03-01

    Environmental and physiological variations influence the steady-state concentration of free oxygen radicals in cells. Because of the seasonal life cycle of Lithodes santolla in the Beagle Channel, a baseline study of the antioxidant physiological variations along the seasons is necessary for a better understanding of its ecophysiology. The aim of this study was to evaluate the seasonal variations in gills, hemolymph, muscle and hepatopancreas of the: i) enzymatic activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione transferase; ii) ascorbic acid and total glutathione; iii) lipid peroxidation and protein oxidation; iv) glucose, proteins and pH. Seasonality found in the antioxidant defense system of L. santolla from the Beagle Channel acts in a collaborative way during the most relevant life cycle phases (reproduction and molting), avoiding a long term oxidative stress. The antioxidant system also shows changes in the enzymatic activities likely caused by the environmental factors, such as low temperatures during winter and spring seasons. PMID:25433337

  17. Implementation of multi-channel electronics system for astrophysical reaction studies at ORNL

    NASA Astrophysics Data System (ADS)

    Ahn, S. H.; Jones, K. L.; Matos, M.; Bardayan, D. W.; Chae, K. Y.; Smith, M. S.; Varner, R. J.; Elson, J. M.; Famiano, M. A.

    2010-11-01

    The development of large area, high-granularity silicon detector arrays has created opportunities to study transfer reactions in inverse kinematics with low-intensity radioactive beams. We are developing a new detector array comprised of 24 double-sided silicon strip detectors that will allow measurements with lower thresholds and better resolution than current detectors at ORNL. To instrument this new array, we are implementing ˜2000 channels of signal processing electronics based on application-specific integrated circuits (ASICs) designed at Washington University. The ASICs handle pulse shaping, timing, triggering, and digitization of 32 channels all on a single chip. In addition, a Real-Time Executive for Multiprocessor Systems (RTEMS) is used for a network communication between the electronics and data acquisition server. Details of the electronics setup and a status report on the devices will be presented. We will also discuss plans to utilize this system for experiments of transfer reactions using radioactive ion beams.

  18. A novel transform domain processing based channel estimation method for OFDM radio-over-fiber systems.

    PubMed

    Tao, Li; Yu, Jianjun; Yang, Qi; Shao, Yufeng; Zhang, Junwen; Chi, Nan

    2013-03-25

    In this paper, a transform domain processing (TDP) based channel estimation method for orthogonal frequency-division multiplexing (OFDM) Radio-over-Fiber (RoF) systems is proposed. Theoretically investigation shows that TDP can greatly reduce the number of required training symbols. An 8 x 4.65 Gb/s multi-user OFDM RoF system over 40 km fiber link and 60 GHz wireless link is experimentally demonstrated utilizing TDP scheme. Compared with conventional time domain averaging (TDA) scheme, the overhead can be reduced from several tens of training symbols to merely one symbol and the receiver sensitivity has been improved by 1.8 dB at BER of 3.8 x 10(-3). The calculated BER performance for 8 wireless users clearly validates the feasibility of this TDP-based channel estimation method. PMID:23546130

  19. Seismic features and evolution of a late Miocene submarine channel system in the Yinggehai basin, northwestern South China Sea

    NASA Astrophysics Data System (ADS)

    Sun, H.; Jiang, T.; Wang, Z.; Zhang, Y.

    2014-12-01

    Submarine channel is one of key conduits for coarse terrigenous clastic sediments to abyssal plain, which provides the possibility for deepwater hydrocarbon exploration. Recently, a new high-quality 3D seismic data is acquired in south Yinggehai basin (YGHB) and the detailed interpretations on those seismic profiles as well as RMS amplitude attributes and variance slices reveal a submarine channel system developed in late Miocene, which could be supplied from Hainan Island via turbidity currents so that it would be filled with sand-rich turbidites as good hydrocarbon reservoir. Based on the integration between regional seismic survey and some boreholes, the investigations on its infilling architectures and depositional processes are carried out. The results show that it composes two converged submarine channels with two channelized submarine fans to their west and the main submarine channel (MSC) is characterized by a downstream increasing width and is infilled by sediments with high amplitude seismic facies, which could be originated from channelized submarine fans. Furthermore, the complicated depositional processes around the confluence region of these two channels are pointed out and the interactions between the submarine channel system and nearby channelized submarine fans are discussed. The detailed illustration on the seismic features and depositional processes of the subsurface submarine system provides us better understanding deepwater sedimentary dynamics and would be more benefit for the hydrocarbon exploration in similar deepwater area around the world.

  20. Application of the Hardman methodology to the Single Channel Ground-Airborne Radio System (SINCGARS)

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The HARDMAN methodology was applied to the various configurations of employment for an emerging Army multipurpose communications system. The methodology was used to analyze the manpower, personnel and training (MPT) requirements and associated costs, of the system concepts responsive to the Army's requirement for the Single Channel Ground-Airborne Radio System (SINCGARS). The scope of the application includes the analysis of two conceptual designs Cincinnati Electronics and ITT Aerospace/Optical Division for operating and maintenance support addressed through the general support maintenance echelon.

  1. A model for the I/O-channel traffic in computer systems.

    NASA Technical Reports Server (NTRS)

    Kuemmerle, K.

    1972-01-01

    A new model is proposed which is based on the assumption that the actual traffic to be processed by an I/O channel system is generated as the overflow from a fictitious server system having Poisson traffic as the input. The number of servers and the mean arrival rate can be readily adjusted to verify the main value and the variance of the actual traffic to be handled. A closed solution for the stationary probabilities of state is obtained, and the parameters conventionally used to describe the grade of performance of queuing systems (such as mean queue length, mean waiting time, and probability of waiting) are defined.

  2. A simple three-channel dc SQUID system using time domain multiplexing

    NASA Astrophysics Data System (ADS)

    Mück, M.; Korn, M.; Mugford, C. G. A.; Kycia, J. B.

    2004-08-01

    Conventional multichannel superconducting quantum interference device (SQUID) systems require a SQUID read-out circuit for each channel, as well as many wires connecting each individual SQUID and feedback coil to the room temperature electronics. We present a simple time domain multiplexed read-out scheme which requires only a single SQUID read-out circuit that is successively switched between all the SQUIDs. By connecting all the SQUIDs and all the feedback coils in series, this time domain multiplexed system requires many fewer wires between the SQUIDs and the room temperature read-out circuit than other multichannel systems.

  3. Characterization and calibration of 8-channel E-band heterodyne radiometer system for SST-1 tokamak

    SciTech Connect

    Siju, Varsha; Kumar, Dharmendra; Shukla, Praveena; Pathak, S. K.

    2014-05-15

    An 8-channel E-band heterodyne radiometer system (74–86 GHz) is designed, characterized, and calibrated to measure the radial electron temperature profile by measuring Electron Cyclotron Emission spectrum at SST-1 Tokamak. The developed radiometer has a noise equivalent temperature of 1 eV and sensitivity of 5 × 10{sup 9} V/W. In order to precisely measure the absolute value of electron temperature, a calibration measurement of the radiometer system is performed using hot-cold Dicke switch method, which confirms the system linearity.

  4. 8-channel acquisition system for time-correlated single-photon counting

    NASA Astrophysics Data System (ADS)

    Antonioli, S.; Miari, L.; Cuccato, A.; Crotti, M.; Rech, I.; Ghioni, M.

    2013-06-01

    Nowadays, an increasing number of applications require high-performance analytical instruments capable to detect the temporal trend of weak and fast light signals with picosecond time resolution. The Time-Correlated Single-Photon Counting (TCSPC) technique is currently one of the preferable solutions when such critical optical signals have to be analyzed and it is fully exploited in biomedical and chemical research fields, as well as in security and space applications. Recent progress in the field of single-photon detector arrays is pushing research towards the development of high performance multichannel TCSPC systems, opening the way to modern time-resolved multi-dimensional optical analysis. In this paper we describe a new 8-channel high-performance TCSPC acquisition system, designed to be compact and versatile, to be used in modern TCSPC measurement setups. We designed a novel integrated circuit including a multichannel Time-to-Amplitude Converter with variable full-scale range, a D/A converter, and a parallel adder stage. The latter is used to adapt each converter output to the input dynamic range of a commercial 8-channel Analog-to-Digital Converter, while the integrated DAC implements the dithering technique with as small as possible area occupation. The use of this monolithic circuit made the design of a scalable system of very small dimensions (95 × 40 mm) and low power consumption (6 W) possible. Data acquired from the TCSPC measurement are digitally processed and stored inside an FPGA (Field-Programmable Gate Array), while a USB transceiver allows real-time transmission of up to eight TCSPC histograms to a remote PC. Eventually, the experimental results demonstrate that the acquisition system performs TCSPC measurements with high conversion rate (up to 5 MHz/channel), extremely low differential nonlinearity (<0.04 peak-to-peak of the time bin width), high time resolution (down to 20 ps Full-Width Half-Maximum), and very low crosstalk between channels.

  5. 8-Channel acquisition system for Time-Correlated Single-Photon Counting.

    PubMed

    Antonioli, S; Miari, L; Cuccato, A; Crotti, M; Rech, I; Ghioni, M

    2013-06-01

    Nowadays, an increasing number of applications require high-performance analytical instruments capable to detect the temporal trend of weak and fast light signals with picosecond time resolution. The Time-Correlated Single-Photon Counting (TCSPC) technique is currently one of the preferable solutions when such critical optical signals have to be analyzed and it is fully exploited in biomedical and chemical research fields, as well as in security and space applications. Recent progress in the field of single-photon detector arrays is pushing research towards the development of high performance multichannel TCSPC systems, opening the way to modern time-resolved multi-dimensional optical analysis. In this paper we describe a new 8-channel high-performance TCSPC acquisition system, designed to be compact and versatile, to be used in modern TCSPC measurement setups. We designed a novel integrated circuit including a multichannel Time-to-Amplitude Converter with variable full-scale range, a D∕A converter, and a parallel adder stage. The latter is used to adapt each converter output to the input dynamic range of a commercial 8-channel Analog-to-Digital Converter, while the integrated DAC implements the dithering technique with as small as possible area occupation. The use of this monolithic circuit made the design of a scalable system of very small dimensions (95 × 40 mm) and low power consumption (6 W) possible. Data acquired from the TCSPC measurement are digitally processed and stored inside an FPGA (Field-Programmable Gate Array), while a USB transceiver allows real-time transmission of up to eight TCSPC histograms to a remote PC. Eventually, the experimental results demonstrate that the acquisition system performs TCSPC measurements with high conversion rate (up to 5 MHz/channel), extremely low differential nonlinearity (<0.04 peak-to-peak of the time bin width), high time resolution (down to 20 ps Full-Width Half-Maximum), and very low crosstalk between channels

  6. A Parallel Double Front System along the Main Channel of a Barotropic Tidal Inlet

    NASA Astrophysics Data System (ADS)

    Li, C.

    2003-12-01

    In an estuary with a significant longitudinal density gradient, fronts can occur during flood stage if a cross channel shear of flow exists. In a wide estuary, models have suggested convergence on the right hand side when facing the downstream direction, because of Coriolis effect, favoring a single front line changing its position with tidal phase. If a front system occurs during different tidal stages including ebb and appears in pairs on both sides of a channel, then neither of the above mechanisms can explain it. Here I report such a front system observed in a barotropic tidal inlet - Sand Shoal Inlet, VA. The front system is observed during different tidal stages within a 13-hour observation period. A 25-ft boat is used to tow an acoustic Doppler current profiler (ADCP) to measure velocity profiles along an hour-glass shaped ship track. A harmonic-statistic analysis is used to analyze the tide, tidal velocity, and mean velocity. The transverse convergence and divergence of velocity are calculated. The rms errors of the harmonic-statistic analysis of the elevation and velocity are about 0.28 m and 0.13 m/s (with a maximum velocity of over 2 m/s), respectively. On average, about 83%, 95%, and 70% of the variabilities of the elevation, longitudinal and transverse velocities respectively can be explained by the M2 tidal and subtidal constituents. Strong transverse velocity convergences are identified by the analysis and are generally consistent with the observed front positions. The analysis shows that the front system is apparently generated by a combination of several mechanisms including (1) differential rotation of the tidal ellipses and spatial variations of the major axes of the tidal ellipses, owing to the strong bottom friction, and (2) a strong geometric convergence at the inlet. Density effect is found to be negligible and the planetary vorticity tilt effect is also unimportant because of a much higher relative vorticity. The observed front system is

  7. A dual-channel fusion system of visual and infrared images based on color transfer

    NASA Astrophysics Data System (ADS)

    Pei, Chuang; Jiang, Xiao-yu; Zhang, Peng-wei; Liang, Hao-cong

    2013-09-01

    A dual-channel fusion system of visual and infrared images based on color transfer The increasing availability and deployment of imaging sensors operating in multiple spectrums has led to a large research effort in image fusion, resulting in a plethora of pixel-level image fusion algorithms. However, most of these algorithms have gray or false color fusion results which are not adapt to human vision. Transfer color from a day-time reference image to get natural color fusion result is an effective way to solve this problem, but the computation cost of color transfer is expensive and can't meet the request of real-time image processing. We developed a dual-channel infrared and visual images fusion system based on TMS320DM642 digital signal processing chip. The system is divided into image acquisition and registration unit, image fusion processing unit, system control unit and image fusion result out-put unit. The image registration of dual-channel images is realized by combining hardware and software methods in the system. False color image fusion algorithm in RGB color space is used to get R-G fused image, then the system chooses a reference image to transfer color to the fusion result. A color lookup table based on statistical properties of images is proposed to solve the complexity computation problem in color transfer. The mapping calculation between the standard lookup table and the improved color lookup table is simple and only once for a fixed scene. The real-time fusion and natural colorization of infrared and visual images are realized by this system. The experimental result shows that the color-transferred images have a natural color perception to human eyes, and can highlight the targets effectively with clear background details. Human observers with this system will be able to interpret the image better and faster, thereby improving situational awareness and reducing target detection time.

  8. Environmental testing of a prototypic digital safety channel, phase I: System design and test methodology

    SciTech Connect

    Korsah, K.; Turner, G.W.; Mullens, J.A.

    1995-02-01

    A microprocessor-based reactor trip channel has been assembled for environmental testing under an Instrumentation and Control (I&C) Qualification Program sponsored by the U.S. Nuclear Regulatory Commission. The goal of this program is to establish the technical basis for the qualification of advanced I&C systems. The trip channel implemented for this study employs technologies and digital subsystems representative of those proposed for use in some advanced light-water reactors (ALNWS) such as the Simplified Boiling Water Reactor (SBNW) and AP600. It is expected that these tests will reveal any potential system vulnerabilities for technologies representative of those proposed for use in ALNWS. The experimental channel will be purposely stressed considerably beyond what it is likely to experience in a normal nuclear power plant environment, so that the tests can uncover the worst-case failure modes (i.e., failures that are likely to prevent an entire trip system from performing its safety function when required to do so). Based on information obtained from this study, it may be possible to recommend tests that are likely to indicate the presence of such failure mechanisms. Such recommendations would be helpful in augmenting current qualification guidelines.

  9. Transporters, channels, or simple diffusion? Dogmas, atypical roles and complexity in transport systems.

    PubMed

    Conde, Artur; Diallinas, George; Chaumont, François; Chaves, Manuela; Gerós, Hernâni

    2010-06-01

    The recent breakthrough discoveries of transport systems assigned with atypical functions provide evidence for complexity in membrane transport biochemistry. Some channels are far from being simple pores creating hydrophilic passages for solutes and can, unexpectedly, act as enzymes, or mediate high-affinity uptake, and some transporters are surprisingly able to function as sensors, channels or even enzymes. Furthermore, numerous transport studies have demonstrated complex multiphasic uptake kinetics for organic and mineral nutrients. The biphasic kinetics of glucose uptake in Saccharomyces cerevisiae, a result of several genetically distinct uptake systems operating simultaneously, is a classical example that is a subject of continuous debate. In contrast, some transporters display biphasic kinetics, being bona fidae dual-affinity transporters, their kinetic properties often modulated by post-translational regulation. Also, aquaporins have recently been reported to exhibit diverse transport properties and can behave as highly adapted, multifunctional channels, transporting solutes such as CO(2), hydrogen peroxide, urea, ammonia, glycerol, polyols, carbamides, purines and pyrimidines, metalloids, glycine, and lactic acid, rather than being simple water pores. The present review provides an overview on some atypical functions displayed by transporter proteins and discusses how this novel knowledge on cellular uptake systems may be related to complex multiphasic uptake kinetics often seen in a wide variety of living organisms and the intriguing diffusive uptake of sugars and other solutes. PMID:20026419

  10. Extended horizon lifting for periodic gain adjustment in control systems, and for equalization of communication channels

    NASA Technical Reports Server (NTRS)

    Bayard, David S. (Inventor)

    1994-01-01

    Periodic gain adjustment in plants of irreducible order, n, or for equalization of communications channels is effected in such a way that the plant (system) appears to be minimum phase by choosing a horizon time N is greater than n of liftings in periodic input and output windows rho sub u and rho sub y, respectively, where N is an integer chosen to define the extent (length) of each of the windows rho sub u and rho sub y, and n is the order of an irreducible input/output plant. The plant may be an electrical, mechanical, or chemical system, in which case output tracking (OT) is carried out for feedback control or a communication channel, in which case input tracking (IT) is performed. Conditions for OT are distinct from IT in terms of zero annihilation, namely H(sub s)H(sub s)(sup +) = I for OT and H(sub s)H(sub s)(sup +) = I of IT, where the OT conditions are intended for gain adjustments in the control system, and IT conditions are intended for equalization for communication channels.

  11. An automated injection system for sub-micron sized channels used in shear-driven-chromatography.

    PubMed

    De Malsche, Wim; Clicq, David; Eghbali, Hamed; Fekete, Veronika; Gardeniers, Han; Desmet, Gert

    2006-10-01

    This paper describes a method to automatically and reproducibly inject sharply delimited sample plugs in the shallow (i.e., sub-micron) channels typically used in shear driven chromatography. The formation of asymmetric plugs, which typically occurs during loading of the sample in wide channels, is circumvented by etching a slit in the middle of the channel that is connected to a micro-well and a vacuum system with syringes for the supply of both the analyte and the mobile phase. The design of the injection slit was supported by a series of CFD simulations to optimize its shape and that of the corresponding injection well. The system was intensively tested experimentally and showed good reproducibility, both for the width and the area of the injected peaks (relative standard deviations are max. 4 and 6%, respectively). The concentration of the injected plug was found to be approximately 80% of the original sample concentration. It was also observed that with the current setup the lower limit of the peak width was about 120 microm. This is a consequence of the fact that the peak width originating from the convection filling step becomes negligible to the contribution of diffusion during the filling and flushing time. Being fully automated and perfectly closed, the presently proposed injection system also paves the way to integrate other functionalities in shear driven chromatography, i.e. gradient elution and parallelization. PMID:17102846

  12. Environmental testing of a prototypic digital safety channel, Phase I: System design and test methodology

    SciTech Connect

    Korsah, K.; Turner, G.W.; Mullens, J.A.

    1995-04-01

    A microprocessor-based reactor trip channel has been assembled for environmental testing under an Instrumentation and Control (I&C) Qualification Program sponsored by the US Nuclear Regulatory Commission. The goal of this program is to establish the technical basis and acceptance criteria for the qualification of advanced I&C systems. The trip channel implemented for this study employs technologies and digital subsystems representative of those proposed for use in some advanced light-water reactors (ALWRs) such as the Simplified Boiling Water Reactor (SBWR). It is expected that these tests will reveal any potential system vulnerabilities for technologies representative of those proposed for use in ALWRs. The experimental channel will be purposely stressed considerably beyond what it is likely to experience in a normal nuclear power plant environment, so that the tests can uncover the worst-case failure modes (i.e., failures that are likely to prevent an entire trip system from performing its safety function when required to do so). Based on information obtained from this study, it may be possible to recommend tests that are likely to indicate the presence of such failure mechanisms. Such recommendations would be helpful in augmenting current qualification guidelines.

  13. A sophisticated, multi-channel data acquisition and processing system for high frequency noise research

    NASA Technical Reports Server (NTRS)

    Hall, David G.; Bridges, James

    1992-01-01

    A sophisticated, multi-channel computerized data acquisition and processing system was developed at the NASA LeRC for use in noise experiments. This technology, which is available for transfer to industry, provides a convenient, cost-effective alternative to analog tape recording for high frequency acoustic measurements. This system provides 32-channel acquisition of microphone signals with an analysis bandwidth up to 100 kHz per channel. Cost was minimized through the use of off-the-shelf components. Requirements to allow for future expansion were met by choosing equipment which adheres to established industry standards for hardware and software. Data processing capabilities include narrow band and 1/3 octave spectral analysis, compensation for microphone frequency response/directivity, and correction of acoustic data to standard day conditions. The system was used successfully in a major wind tunnel test program at NASA LeRC to acquire and analyze jet noise data in support of the High Speed Civil Transport (HSCT) program.

  14. Designing Effective Persuasive Systems Utilizing the Power of Entanglement: Communication Channel, Strategy and Affect

    NASA Astrophysics Data System (ADS)

    Li, Haiqing; Chatterjee, Samir

    With rapid advances in information and communication technology, computer-mediated communication (CMC) technologies are utilizing multiple IT platforms such as email, websites, cell-phones/PDAs, social networking sites, and gaming environments. However, no studies have compared the effectiveness of a persuasive system using such alternative channels and various persuasive techniques. Moreover, how affective computing impacts the effectiveness of persuasive systems is not clear. This study proposes (1) persuasive technology channels in combination with persuasive strategies will have different persuasive effectiveness; (2) Adding positive emotion to a message that leads to a better overall user experience could increase persuasive effectiveness. The affective computing or emotion information was added to the experiment using emoticons. The initial results of a pilot study show that computer-mediated communication channels along with various persuasive strategies can affect the persuasive effectiveness to varying degrees. These results also shows that adding a positive emoticon to a message leads to a better user experience which increases the overall persuasive effectiveness of a system.

  15. Performance analysis of a finite radon transform in OFDM system under different channel models

    SciTech Connect

    Dawood, Sameer A.; Anuar, M. S.; Fayadh, Rashid A.; Malek, F.; Abdullah, Farrah Salwani

    2015-05-15

    In this paper, a class of discrete Radon transforms namely Finite Radon Transform (FRAT) was proposed as a modulation technique in the realization of Orthogonal Frequency Division Multiplexing (OFDM). The proposed FRAT operates as a data mapper in the OFDM transceiver instead of the conventional phase shift mapping and quadrature amplitude mapping that are usually used with the standard OFDM based on Fast Fourier Transform (FFT), by the way that ensure increasing the orthogonality of the system. The Fourier domain approach was found here to be the more suitable way for obtaining the forward and inverse FRAT. This structure resulted in a more suitable realization of conventional FFT- OFDM. It was shown that this application increases the orthogonality significantly in this case due to the use of Inverse Fast Fourier Transform (IFFT) twice, namely, in the data mapping and in the sub-carrier modulation also due to the use of an efficient algorithm in determining the FRAT coefficients called the optimal ordering method. The proposed approach was tested and compared with conventional OFDM, for additive white Gaussian noise (AWGN) channel, flat fading channel, and multi-path frequency selective fading channel. The obtained results showed that the proposed system has improved the bit error rate (BER) performance by reducing inter-symbol interference (ISI) and inter-carrier interference (ICI), comparing with conventional OFDM system.

  16. Development of eight-channel methane gas optical fiber sensing system

    NASA Astrophysics Data System (ADS)

    Zhang, Tianyu; Wang, Weiqi; Gao, Liancong; Koscica, Thomas; Li, David

    2012-10-01

    This paper introduces an eight-channel methane gas optical fiber sensing system designed for underground coalmine methane gas monitoring. With eight self-designed gas sensor heads, this system can detect the concentration of methane gas at eight locations in a coal mine simultaneously. By wavelength modulation with the DFB laser diode, 1×8 WDM, a self-designed processing circuit, and data processing software, this system features a high sensitivity (10ppb). The response time of the system is less than 6 seconds. Extensive tests have been carried out on the system. It is shown that the performance of the optical fiber sensor system is generally better than conventional methane sensing systems currently in wide use in coalmines. It can be used in the coalmines for multi-point gas detecting using one light source and attendant central processing unit only, resulting in more versatility, reduced cost, and increased perational efficiency.

  17. Leader-following consensus of high-order multi-agent linear systems with bounded transmission channels

    NASA Astrophysics Data System (ADS)

    Ni, Wei; Xiong, Chun; Yang, Jie

    2013-09-01

    The leader-following consensus of high-order multi-agent linear systems with bounded transmission channels is considered. Agents modelled as LTI dynamics exchange information according to a network which can be described as a graph with agents as its vertices and information transmission channels as its edges. The transmission channels are bounded. The objective is leader-following in the sense that the state of all agents should converge to that of the leader vehicle. Detailed analysis of the leader-following consensus under bounded transmission channels is investigated for both fixed and switching network topologies.

  18. Effect of channel catfish stocking rate on yield and water quality in an intensive, mixed suspended-growth production system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to determine the effect of channel catfish (Ictalurus punctatus) stocking rate on yield and water quality in a mixed suspended-growth production system (bio-floc) with zero water exchange. Channel catfish (National Warmwater Aquaculture Center 103 strain; average weight = 13...

  19. Eight channel - 16 bit, bidirectional analog to digital monitoring and control system

    SciTech Connect

    Allen, J.C.; Callis, R.W.; Cary, W.P.; Harris, T.E.; Nerem, A.

    1991-11-01

    The DIII-D tokamak facility is currently upgrading its electron cyclotron resonance heating (ECH) system. The new system is based on 110 GHz gyrotrons developed by Varian. As part of this upgrade, the superconducting magnet power supplies were required to be remotely controlled and monitored accurately. The 110 GHz gyrotron superconducting magnet has eight coils, that are energized by current regulating power supplies. An analog to digital (A/D) system was designed to allow remote coil current monitoring and power supply programming. The A/D system is an eight channel multiplexed, 16 bit, bidirectional, fiber optically linked, analog to digital telemetry system. Design concerns and trade-offs will be discussed as will the results of in system use.

  20. Design and application of multi-channel simultaneous detection system for well-earth potential

    NASA Astrophysics Data System (ADS)

    Lei, Shao; Jun, Lin; Wei, Jianrong; Sui, Yangyi; Wu, Ziyu

    2007-07-01

    Well-earth ERT (electrical resistance tomography) technology is an important geophysical exploration method which studies the location distribution of remaining oil. Based on virtual instrument technology, the author designs a set of multi-channel simultaneous detection system. It adopts multi-channel simultaneous sampling, bipolar and differential inputs, analog LPF (low pass filter), FIR digital filter, and linear accumulated digital averaging method or techniques to suppress electromagnetic noise and improve SNR (signal-to-noise ratio); uses digital signal process method to remove the overshoot, avoided huge errors and improved accuracy of measurement; adopts feedback compensative method to exclude the influence of SP(spontaneous potential) and cover a wide dynamic measurable scope; spectrum analysis method is used for judging all electrodes earthing situation correctly; the USB2.0 technique is used to solve the problem of bulky multi-channel data transmission to achieve high-speed data transmission between hardware and PC. The Liao He oilfield survey results show that the system is characterized with high efficiency, portable and strong antijiamming capability.

  1. A wireless multi-channel bioimpedance measurement system for personalized healthcare and lifestyle.

    PubMed

    Ramos, Javier; Ausín, José Luis; Lorido, Antonio Manuel; Redondo, Francisco; Duque-Carrillo, Juan Francisco

    2013-01-01

    Miniaturized, noninvasive, wearable sensors constitute a fundamental prerequisite for pervasive, predictive, and preventive healthcare systems. In this sense, this paper presents the design, realization, and evaluation of a wireless multi-channel measurement system based on a cost-effective high-performance integrated circuit for electrical bioimpedance (EBI) measurements in the frequency range from 1 kHz to 1 MHz. The resulting on-chip spectrometer provides high measuring EBI capabilities and together with a low-cost, commercially available radio frequency transceiver device. It provides reliable wireless communication, constitutes the basic node to build EBI wireless sensor networks (EBI-WSNs). The proposed EBI-WSN behaves as a high-performance wireless multi-channel EBI spectrometer, where the number of channels is completely scalable and independently configurable to satisfy specific measurement requirements of each individual. A prototype of the EBI node leads to a very small printed circuit board of approximately 8 cm2 including chip-antenna, which can operate several years on one 3-V coin cell battery and make it suitable for long-term preventive healthcare monitoring. PMID:23739358

  2. Systems biology of ion channels and transporters in tumor angiogenesis: An omics view.

    PubMed

    Munaron, L

    2015-10-01

    Solid tumors require the formation of new blood vessels to support their growth, invasiveness and metastatic potential. Tumor neovascularization is achieved by vasculogenesis from endothelial precursors and by sprouting angiogenesis from preexisting vessels. The complex sequence of events driving these processes, including endothelial activation, proliferation, migration and differentiation, is associated with fluxes of ions, water and other small molecules mediated by a great pool of ion channels and transporters (ICT). This 'transportome' is regulated by environmental factors as well as intracellular signaling molecules. In turn, ICT play a prominent role in the response to angiogenesis-related stimuli through canonical and 'unconventional' activities: indeed, there is an increasing recognition of the multifunctionality of several ion channels that could also be annotated as receptors, enzymes, scaffolding proteins, mechanical and chemical sensors. The investigation of ICT structure and function has been far from the experimental oncology for long time and these two domains converged only very recently. Furthermore, the systems biology viewpoint has not received much attention in the biology of cancer transportome. Modulating angiogenesis by interference with membrane transport has a great potential in cancer treatment and the application of an 'omics' logic will hopefully contribute to the overall advancement in the field. This review is an attempt to apply the systems biology approach to the analysis of ICT involved in tumor angiogenesis, with a particular focus on endothelial transportome diversity. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers. PMID:25450338

  3. Performance Evaluation of Multi-Channel Wireless Mesh Networks with Embedded Systems

    PubMed Central

    Lam, Jun Huy; Lee, Sang-Gon; Tan, Whye Kit

    2012-01-01

    Many commercial wireless mesh network (WMN) products are available in the marketplace with their own proprietary standards, but interoperability among the different vendors is not possible. Open source communities have their own WMN implementation in accordance with the IEEE 802.11s draft standard, Linux open80211s project and FreeBSD WMN implementation. While some studies have focused on the test bed of WMNs based on the open80211s project, none are based on the FreeBSD. In this paper, we built an embedded system using the FreeBSD WMN implementation that utilizes two channels and evaluated its performance. This implementation allows the legacy system to connect to the WMN independent of the type of platform and distributes the load between the two non-overlapping channels. One channel is used for the backhaul connection and the other one is used to connect to the stations to wireless mesh network. By using the power efficient 802.11 technology, this device can also be used as a gateway for the wireless sensor network (WSN). PMID:22368482

  4. Performance evaluation of multi-channel wireless mesh networks with embedded systems.

    PubMed

    Lam, Jun Huy; Lee, Sang-Gon; Tan, Whye Kit

    2012-01-01

    Many commercial wireless mesh network (WMN) products are available in the marketplace with their own proprietary standards, but interoperability among the different vendors is not possible. Open source communities have their own WMN implementation in accordance with the IEEE 802.11s draft standard, Linux open80211s project and FreeBSD WMN implementation. While some studies have focused on the test bed of WMNs based on the open80211s project, none are based on the FreeBSD. In this paper, we built an embedded system using the FreeBSD WMN implementation that utilizes two channels and evaluated its performance. This implementation allows the legacy system to connect to the WMN independent of the type of platform and distributes the load between the two non-overlapping channels. One channel is used for the backhaul connection and the other one is used to connect to the stations to wireless mesh network. By using the power efficient 802.11 technology, this device can also be used as a gateway for the wireless sensor network (WSN). PMID:22368482

  5. One bit/s/Hz Spectrally Efficient Transmission for an Eight-Channel NRZ-Modulated DWDM System

    NASA Astrophysics Data System (ADS)

    Vij, Robin; Sharma, Neeraj

    2016-03-01

    The core of the global telecommunication network consists of wavelength-division multiplexed (WDM) optical transmission systems. WDM is the technology of choice as it allows for a high spectral efficiency. We propose an effective way to counter the nonlinearities like four-wave mixing and cross-phase modulation to achieve the spectral efficiency of 1 bit/s/Hz using non-return-to-zero (NRZ) modulation format. We use the concept of non-uniform channel spacing and non-uniform power assignment between adjacent channels of the WDM system. We have simulated an eight-channel WDM lightwave system with bit rates of 10 and 25 Gbit/s.

  6. Under-sampling in a Multiple-Channel Laser Vibrometry System

    SciTech Connect

    Corey, J

    2006-08-15

    Laser vibrometry is a technique used to detect vibrations on objects using the interference of coherent light with itself. Most vibrometry systems process only one target location at a time, but processing multiple locations simultaneously provides improved detection capabilities. Traditional laser vibrometry systems employ oversampling to sample the incoming modulated-light signal, however as the number of channels increases in these systems, certain issues arise such a higher computational cost, excessive heat, increased power requirements, and increased component cost. This thesis describes a novel approach to laser vibrometry that utilizes undersampling to control the undesirable issues associated with over-sampled systems. Undersampling allows for significantly less samples to represent the modulated-light signals, which offers several advantages in the overall system design. These advantages include an improvement in thermal efficiency, lower processing requirements, and a higher immunity to the relative intensity noise inherent in laser vibrometry applications. A unique feature of this implementation is the use of a parallel architecture to increase the overall system throughput. This parallelism is realized using a hierarchical multi-channel architecture based on off-the-shelf programmable logic devices (PLDs).

  7. Development of 200-channel mapping system for tissue oxygenation measured by near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Niwayama, Masatsugu; Kohata, Daisuke; Shao, Jun; Kudo, Nobuki; Hamaoka, Takatumi; Katsumura, Toshihito; Yamamoto, Katsuyuki

    2000-07-01

    Near-infrared spectroscopy (NIRS) is a very useful technique for noninvasive measurement of tissue oxygenation. Among various methods of NIRS, continuous wave near-infrared spectroscopy (CW- NIRS) is especially suitable for real-time measurement and for practical use. CW-NIRS has recently been applied in vivo reflectance imaging of muscle oxygenation and brain activity. However, conventional mapping systems do not have a sufficient mapping area at present. Moreover, they do not enable quantitative measurement of tissue oxygenation because conventional NIRS is based on the inappropriate assumption that tissue is homogeneous. In this study, we developed a 200-channel mapping system that enables measurement of changes in oxygenation and blood volume and that covers a wider area (30 cm x 20 cm) than do conventional systems. The spatial resolution (source- detector separation) of this system is 15 mm. As for the effcts of tissue inhomogeneity on muscle oxygenation measurement, subcutaneous adipose tissue greatly reduces measurement sensitivity. Therefore, we also used a correction method for influence of the subcutaneous fat layer so that we could obtain quantitative changes in concentrations of oxy- and deoxy- hemoglobin. We conducted exercise tests and measured the changed in hemoglobin concentration in the thigh using the new system. The working muscles in the exercises could be imaged, and the heterogeneity of the muscles was shown. These results demonstrated the new 200-channel mapping system enables observation of the distribution of muscle metabolism and localization of muscle function.

  8. Cat-eye target imaging system research and dual-channel DSP implementation

    NASA Astrophysics Data System (ADS)

    Zheng, Zheng; Zhang, Haiyang; Shi, Guang; Han, Lei; Zhao, Changming

    2013-09-01

    In modern warfare, well-equipped and trained snipers have become a mortal malady for the combat troops. How to accurately, timely and quickly find and destroy snipers becomes a research focus of national military experts. In order to effectively detect faint echo signal of cat-eye target and get the snipers' position information in the detection area, a small size of dual-channel active laser detection system with monochrome and color Charge-couple Devices(CCD) is designed, which is based on the laser imaging principle of cat-eye effect, associated tests are also conducted. The dual-channel video capture can obtain more information of target area, while taking advantage of the high sensitivity of monochrome CCD will also provide more accurate grayscale information for the video image processing. In order to achieve the miniaturization of system, we choose a video processing board whose size is only 54mm*90mm as hardware platform to complete the algorithm. For verifying the feasibility and accuracy of algorithm, we ultimately build a full set of experimental detection system. The test results show that the system can accurately detect and mark typical cat-eye target from background under different distances, which verifies the rationality and validity of the proposed system and has certain practicality and promotion in the active laser detection system research areas.

  9. Coupled-rearrangement-channels calculation of the three-body system under the absorbing boundary condition

    NASA Astrophysics Data System (ADS)

    Iwasaki, M.; Otani, R.; Ito, M.; Kamimura, M.

    2016-06-01

    We formulate the absorbing boundary condition (ABC) in the coupled rearrangement-channels variational method (CRCVM) for the three-body problem. The absorbing potential is introduced in the system of the identical three-bosons, on which the boson symmetry is explicitly imposed by considering the rearrangement channels. The resonance parameters and the strength of the monopole breakup are calculated by the CRCVM + ABC method, and the results are compared with the complex scaling method (CSM). We have found that the results of the ABC method are consistent with the CSM results. The effect of the boson symmetry, which is often neglected in the calculation of the triple α reactions, is also discussed.

  10. A multi-channel readout electronics system for GEM and MICROMEGAS

    NASA Astrophysics Data System (ADS)

    Deng, Z.; Li, Y. L.; Gong, G. H.; Gong, H.; Luo, J.; Liu, Y. N.

    2009-11-01

    A multi-channel readout electronics system for GEM and MICROMEGAS has been developed. It consists of a front-end ASIC, a multi-channel ADC and a FPGA to sample the signal waveforms in real time. The gain of the front-end ASIC can be programmable from 1 mV/fC to 19 mV/fC and the output pulse width can be adjusted from 200 ns to 800 ns. The ENC is measured to be below 2000 e for Cin < 20 pF and below 5000 e for Cin < 60 pF. Detailed circuit performance and test results with detectors will be described in this paper.

  11. Optical-network-connected multi-channel 96-GHz-band distributed radar system

    NASA Astrophysics Data System (ADS)

    Kanno, Atsushi; Kuri, Toshiaki; Kawanishi, Tetsuya

    2015-05-01

    The millimeter-wave (MMW) radar is a promising candidate for high-precision imaging because of its short wavelength and broad range of available bandwidths. In particular in the frequency range of 92-100 GHz, which is regulated for radiolocation, an atmospheric attenuation coefficient less than 1 dB/km limits the imaging range. Therefore, a combination of MMW radar and distributed antenna system directly connected to optical fiber networks can realize both high-precision imaging and large-area surveillance. In this paper, we demonstrate a multi-channel MMW frequency-modulated continuous-wave distributed radar system connected to an analog radio-over-fiber network.

  12. Eugenol dilates mesenteric arteries and reduces systemic BP by activating endothelial cell TRPV4 channels

    PubMed Central

    Peixoto-Neves, Dieniffer; Wang, Qian; Leal-Cardoso, Jose H; Rossoni, Luciana V; Jaggar, Jonathan H

    2015-01-01

    Background and Purpose Eugenol, a vanilloid molecule found in some dietary plants, relaxes vasculature in part via an endothelium-dependent process; however, the mechanisms involved are unclear. Here, we investigated the endothelial cell-mediated mechanism by which eugenol modulates rat mesenteric artery contractility and systemic BP. Experimental Approach The isometric tension of rat mesenteric arteries (size 200–300 μm) was measured using wire myography; non-selective cation currents (ICat) were recorded in endothelial cells using patch clamp electrophysiology. Mean arterial pressure (MAP) and heart rate (HR) were determined in anaesthetized rats. Key Results Eugenol relaxed endothelium-intact arteries in a concentration-dependent manner and this effect was attenuated by endothelium denudation. L-NAME, a NOS inhibitor, a combination of TRAM-34 and apamin, selective blockers of intermediate and small conductance Ca2+-activated K+ channels, respectively, and HC-067047, a TRPV4 channel inhibitor, but not indomethacin, a COX inhibitor, reduced eugenol-induced relaxation in endothelium-intact arteries. Eugenol activated HC-067047-sensitive ICat in mesenteric artery endothelial cells. Short interfering RNA (siRNA)-mediated TRPV4 knockdown abolished eugenol-induced ICat activation. An i.v. injection of eugenol caused an immediate, transient reduction in both MAP and HR, which was followed by prolonged, sustained hypotension in anaesthetized rats. This sustained hypotension was blocked by HC-067047. Conclusions and Implications Eugenol activates TRPV4 channels in mesenteric artery endothelial cells, leading to vasorelaxation, and reduces systemic BP in vivo. Eugenol may be therapeutically useful as an antihypertensive agent and is a viable molecular candidate from which to develop second-generation TRPV4 channel activators that reduce BP. PMID:25832173

  13. 4 channel, 20 ps resolution, monolithic time-to-amplitude converter for multichannel TCSPC systems

    NASA Astrophysics Data System (ADS)

    Crotti, Matteo; Rech, Ivan; Labanca, Ivan; Ghioni, Massimo

    2012-06-01

    Over the past years an always growing interest has arisen about the measurement technique of time-correlated single photon counting (TCSPC) and many applications exploiting TCSPC have been developing in several fields, such as medicine and chemistry. The use of multianode PMTs and of single photon avalanche diode arrays led to the development of acquisition systems with several parallel channels, to employ the TCSPC technique in even more applications. Since TCSPC basically consists in the photons arrival time measurement, the most important part of an acquisition chain is the time measurement block, which must have high resolution and low differential nonlinearity and, in order to implement multidimensional systems, it has to be integrated to reduce both cost and area. To accomplish all these specifications, we have designed and fabricated a 4 channel fully integrated time-to-amplitude converter (TAC), built in 0.35 μm Si-Ge technology, characterized by a variable full scale range from 11 ns to 89 ns, very good time resolution (better than 20 ps FWHM), low differential nonlinearity (better than 0.04 LSB peak-peak and less than 0.2% LSB rms), high counting rate (16 MHz), low and constant power dissipation (50 mW) and low area occupation (340 × 390 μm2 per channel). Our measurements also show a very little crosstalk between converters integrated on the same chip; this feature together with low power and low area make the fabricated converter suitable for parallelization, so that it can be the starting point for future acquisition chains with a high number of parallel channels.

  14. CCSDS Advanced Orbiting Systems Virtual Channel Access Service for QoS MACHETE Model

    NASA Technical Reports Server (NTRS)

    Jennings, Esther H.; Segui, John S.

    2011-01-01

    To support various communications requirements imposed by different missions, interplanetary communication protocols need to be designed, validated, and evaluated carefully. Multimission Advanced Communications Hybrid Environment for Test and Evaluation (MACHETE), described in "Simulator of Space Communication Networks" (NPO-41373), NASA Tech Briefs, Vol. 29, No. 8 (August 2005), p. 44, combines various tools for simulation and performance analysis of space networks. The MACHETE environment supports orbital analysis, link budget analysis, communications network simulations, and hardware-in-the-loop testing. By building abstract behavioral models of network protocols, one can validate performance after identifying the appropriate metrics of interest. The innovators have extended the MACHETE model library to include a generic link-layer Virtual Channel (VC) model supporting quality-of-service (QoS) controls based on IP streams. The main purpose of this generic Virtual Channel model addition was to interface fine-grain flow-based QoS (quality of service) between the network and MAC layers of the QualNet simulator, a commercial component of MACHETE. This software model adds the capability of mapping IP streams, based on header fields, to virtual channel numbers, allowing extended QoS handling at link layer. This feature further refines the QoS v existing at the network layer. QoS at the network layer (e.g. diffserv) supports few QoS classes, so data from one class will be aggregated together; differentiating between flows internal to a class/priority is not supported. By adding QoS classification capability between network and MAC layers through VC, one maps multiple VCs onto the same physical link. Users then specify different VC weights, and different queuing and scheduling policies at the link layer. This VC model supports system performance analysis of various virtual channel link-layer QoS queuing schemes independent of the network-layer QoS systems.

  15. Design and implementation of the parallel processing system of multi-channel polarization images

    NASA Astrophysics Data System (ADS)

    Li, Zhi-yong; Huang, Qin-chao

    2013-08-01

    Compared with traditional optical intensity image processing, polarization images processing has two main problems. One is that the amount of data is larger. The other is that processing tasks is more complex. To resolve these problems, the parallel processing system of multi-channel polarization images is designed by the multi-DSP technique. It contains a communication control unit (CCU) and a data processing array (DPA). CCU controls communications inside and outside the system. Its logics are designed by a FPGA chip. DPA is made up of four Digital Signal Processor (DSP) chips, which are interlinked by the loose coupling method. DPA implements processing tasks including images registration and images synthesis by parallel processing methods. The polarization images parallel processing model is designed on multi levels including the system task, the algorithm and the operation. Its program is designed by the assemble language. While the polarization image resolution is 782x582 pixels, the pixel data length is 12 bits in the experiment. After it received 3 channels of polarization image simultaneously, this system implements parallel task to acquire the target polarization characteristics. Experimental results show that this system has good real-time and reliability. The processing time of images registration is 293.343ms while the registration accuracy achieves 0.5 pixel. The processing time of images synthesis is 3.199ms.

  16. Real-Time Flood Forecasting System Using Channel Flow Routing Model with Updating by Particle Filter

    NASA Astrophysics Data System (ADS)

    Kudo, R.; Chikamori, H.; Nagai, A.

    2008-12-01

    A real-time flood forecasting system using channel flow routing model was developed for runoff forecasting at water gauged and ungaged points along river channels. The system is based on a flood runoff model composed of upstream part models, tributary part models and downstream part models. The upstream part models and tributary part models are lumped rainfall-runoff models, and the downstream part models consist of a lumped rainfall-runoff model for hillslopes adjacent to a river channel and a kinematic flow routing model for a river channel. The flow forecast of this model is updated by Particle filtering of the downstream part model as well as by the extended Kalman filtering of the upstream part model and the tributary part models. The Particle filtering is a simple and powerful updating algorithm for non-linear and non-gaussian system, so that it can be easily applied to the downstream part model without complicated linearization. The presented flood runoff model has an advantage in simlecity of updating procedure to the grid-based distributed models, which is because of less number of state variables. This system was applied to the Gono-kawa River Basin in Japan, and flood forecasting accuracy of the system with both Particle filtering and extended Kalman filtering and that of the system with only extended Kalman filtering were compared. In this study, water gauging stations in the objective basin were divided into two types of stations, that is, reference stations and verification stations. Reference stations ware regarded as ordinary water gauging stations and observed data at these stations are used for calibration and updating of the model. Verification stations ware considered as ungaged or arbitrary points and observed data at these stations are used not for calibration nor updating but for only evaluation of forecasting accuracy. The result confirms that Particle filtering of the downstream part model improves forecasting accuracy of runoff at

  17. Spectral Dynamics Inc., ships hybrid, 316-channel data acquisition system to Sandia Labs.

    SciTech Connect

    Schwartz, Douglas

    2003-09-01

    Spectral Dynamics announced the shipment of a 316-channel data acquisition system. The system was custom designed for the Light Initiated High Explosive (LIHE) facility at Sandia Labs in Albuquerque, New Mexico by Spectral Dynamics Advanced Research Products Group. This Spectral Dynamics data acquisition system was tailored to meet the unique LIHE environmental and testing requirements utilizing Spectral Dynamics commercial off the shelf (COTS) Jaguar and VIDAS products supplemented by SD Alliance partner's (COTS) products. 'This system is just the beginning of our cutting edge merged technology solutions,' stated Mark Remelman, Manager for the Spectral Dynamics Advanced Research Products Group. 'This Hybrid system has 316-channels of data acquisition capability, comprised of 102.4kHz direct to disk acquisition and 2.5MHz, 200Mhz & 500Mhz RAM based capabilities. In addition it incorporates the advanced bridge conditioning and dynamic configuration capabilities offered by Spectral Dynamics new Smart Interface Panel System (SIPS{trademark}).' After acceptance testing, Tony King, the Instrumentation Engineer facilitating the project for the Sandia LIHE group commented; 'The LIHE staff was very impressed with the design, construction, attention to detail and overall performance of the instrumentation system'. This system combines VIDAS, a leading edge fourth generation SD-VXI hardware and field-proven software system from SD's Advanced Research Products Group with SD's Jaguar, a multiple Acquisition Control Peripheral (ACP) system that allows expansion to hundreds of channels without sacrificing signal processing performance. Jaguar incorporates dedicated throughput disks for each ACP providing time streaming to disk at up to the maximum sample rate. Spectral Dynamics, Inc. is a leading worldwide supplier of systems and software for advanced computer-automated data acquisition, vibration testing, structural dynamics, explosive shock, high-speed transient capture

  18. Parthenolide inhibits nociception and neurogenic vasodilatation in the trigeminovascular system by targeting TRPA1 channel

    PubMed Central

    Materazzi, Serena; Benemei, Silvia; Fusi, Camilla; Gualdani, Roberta; De Siena, Gaetano; Vastani, Nisha; Andersson, David A.; Trevisan, Gabriela; Moncelli, Maria Rosa; Wei, Xiaomei; Dussor, Gregory; Pollastro, Federica; Patacchini, Riccardo; Appendino, Giovanni; Geppetti, Pierangelo; Nassini, Romina

    2013-01-01

    While feverfew has been used for centuries to treat pain and headaches and is recommended for migraine treatment, the mechanism for its protective action remains unknown. Migraine is triggered by calcitonin gene-related peptide (CGRP) release from trigeminal neurons. Peptidergic sensory neurons, express a series of transient receptor potential (TRP) channels, including the ankyrin 1 (TRPA1) channel. Recent findings have identified agents either inhaled from the environment or produced endogenously, which are known to trigger migraine or cluster headache attacks, as TRPA1 simulants. A major constituent of feverfew, parthenolide, may interact with TRPA1 nucleophilic sites, suggesting that feverfew antimigraine effect derives from its ability to target TRPA1. We found that parthenolide stimulates recombinant (transfected cells) or natively expressed (rat/mouse trigeminal neurons) TRPA1, where it, however, behaves as a partial agonist. Furthermore, in rodents, after initial stimulation, parthenolide desensitizes the TRPA1 channel, and renders peptidergic, TRPA1-expressing nerve terminals unresponsive to any stimulus. This effect of parthenolide abrogates nociceptive responses evoked by stimulation of peripheral trigeminal endings. TRPA1 targeting and neuronal desensitization by parthenolide inhibits CGRP release from trigeminal neurons and CGRP-mediated meningeal vasodilatation, evoked by either TRPA1 agonists or other unspecific stimuli. TRPA1 partial agonism, together with desensitization and nociceptor defunctionalization, ultimately resulting in inhibition of CGRP release within the trigeminovascular system, may contribute to the antimigraine effect of parthenolide. PMID:23933184

  19. High-throughput hyperpolarized 13C metabolic investigations using a multi-channel acquisition system

    NASA Astrophysics Data System (ADS)

    Lee, Jaehyuk; Ramirez, Marc S.; Walker, Christopher M.; Chen, Yunyun; Yi, Stacey; Sandulache, Vlad C.; Lai, Stephen Y.; Bankson, James A.

    2015-11-01

    Magnetic resonance imaging and spectroscopy of hyperpolarized (HP) compounds such as [1-13C]-pyruvate have shown tremendous potential for offering new insight into disease and response to therapy. New applications of this technology in clinical research and care will require extensive validation in cells and animal models, a process that may be limited by the high cost and modest throughput associated with dynamic nuclear polarization. Relatively wide spectral separation between [1-13C]-pyruvate and its chemical endpoints in vivo are conducive to simultaneous multi-sample measurements, even in the presence of a suboptimal global shim. Multi-channel acquisitions could conserve costs and accelerate experiments by allowing acquisition from multiple independent samples following a single dissolution. Unfortunately, many existing preclinical MRI systems are equipped with only a single channel for broadband acquisitions. In this work, we examine the feasibility of this concept using a broadband multi-channel digital receiver extension and detector arrays that allow concurrent measurement of dynamic spectroscopic data from ex vivo enzyme phantoms, in vitro anaplastic thyroid carcinoma cells, and in vivo in tumor-bearing mice. Throughput and the cost of consumables were improved by up to a factor of four. These preliminary results demonstrate the potential for efficient multi-sample studies employing hyperpolarized agents.

  20. Aircraft Engine On-Line Diagnostics Through Dual-Channel Sensor Measurements: Development of a Baseline System

    NASA Technical Reports Server (NTRS)

    Kobayashi, Takahisa; Simon, Donald L.

    2008-01-01

    In this paper, a baseline system which utilizes dual-channel sensor measurements for aircraft engine on-line diagnostics is developed. This system is composed of a linear on-board engine model (LOBEM) and fault detection and isolation (FDI) logic. The LOBEM provides the analytical third channel against which the dual-channel measurements are compared. When the discrepancy among the triplex channels exceeds a tolerance level, the FDI logic determines the cause of the discrepancy. Through this approach, the baseline system achieves the following objectives: (1) anomaly detection, (2) component fault detection, and (3) sensor fault detection and isolation. The performance of the baseline system is evaluated in a simulation environment using faults in sensors and components.

  1. The Santa Barbara Channel - Santa Maria Basin Study: A model for Coastal Ocean Observing Systems

    NASA Astrophysics Data System (ADS)

    Winant, C. D.

    2002-12-01

    The need to anticipate the potential impact of oil exploration and production activities on coastal resources, and the information needs of agencies charged with responding to coastal emergencies motivated the development of the oil-spill response system for the Santa Barbara Channel (SBC) and the Santa Maria Basin (SMB), along the California coast, between Ventura and Morro Bay. In the Santa Barbara Channel (SBC), moorings and drifter trajectories document a persistent cyclonic circulation with a typical re-circulation period between three and five days. In the spring currents near the mainland are weaker than near the Channel Islands and the overall flow is toward the southeast. Trajectories document the possibility for water parcels to leave the channel through the inter-island passes. In the late fall and winter, a poleward flow with velocities often exceeding 0.5 m/s is confined within 20 km of the mainland. Between these two seasons, the cyclonic tendency is enhanced although most of the drifters eventually migrate westward. The trajectories of drifters released at the same time from sites only 20 km apart can be remarkably different. In the Santa Maria Basin (SMB), the direction and amplitude of the flow is strongly depth dependent. Near the surface, moorings and drifters show the flow to be equatorward except during late fall and early winter when the surface flow is poleward. Beneath the surface layer the flow is poleward except in March and April, right after the spring transition. The observations provide a basis on which several data assimilating model of the circulation are based. The models reproduce all the major observed features of the circulation, including individual drifter trajectories. With little effort these models could be used to maintain an operational predictive capability with real predictive skills over periods of a few days.

  2. A new concept of stereoscopic imaging system using single optical channel and a deflector: pilot study

    NASA Astrophysics Data System (ADS)

    Jang, Won Hyuk; Kang, Heesung; Son, Taeyoon; Park, Jihoon; Jun, Eunkwon; Jung, Byungjo

    2014-03-01

    An imaging system was developed based on single-channel and transparent rotating deflector (TRD) to achieve stereoscopic video imaging. To acquire images at high frame rate, a CMOS camera was used with triggering function allowing image acquisition at certain time point. Stepping motor was controlled to rotate in an arc, stopping at the edge for image acquisition. The acquired 2D images were displayed in stereoscopic 3D using active shutter glasses and conventional display monitor. Using microcontroller (MCU) as centralized control system, system components were controlled and synchronized through using general purpose input/output (GPIO) ports. The created system was evaluated for two factors: motor rotation analysis based on MCU signal generation; and image property based on coefficient of variation calculation.

  3. Toward innovative management of canal systems: determining fundamental properties governing channel flow and transport.

    NASA Astrophysics Data System (ADS)

    Swanson, L. A.; Lunn, R. J.

    2003-04-01

    This research investigates current and future influences on the water quality of canal systems with the aim of designing innovative management strategies for their improvement. The implementation of the Water Framework Directive (WFD) will be particularly significant for canals as it is the first legislation to include artificial impoundments. The WFD requires that the quality of all water bodies is characterised and that ultimately they achieve “good ecological potential”; for such engineered artificial water bodies this potential is as yet undefined. The hydraulic properties of canals are uniquely different from that of natural river systems, influencing factors of particular importance are: the extremely low flow rates (enabling flow directions to be reversed during rainfall events or high winds); the multiple overflow discharge points; the interaction with groundwater; and the regular channel dredging. These lead to unpredictable flow directions, long residence times for pollutants, a lack of rapid dispersion processes and sudden mixing of bed sediment into the water column. This research uses the Union Canal, central Scotland as a case study for fundamental research of advection-dispersion processes in artificial channels. Detailed velocity profiles and dilution gauging experiments have produced unusual results: for example, maximum velocity measurements near the bed of the canal as opposed to just beneath the surface. Research is also focused on understanding the mechanisms governing canal baseline water quality: Sampling data show low levels of DO, coupled with ortho-phosphate concentrations up to 10 times greater than those normally found in rivers. Determining the hydraulic properties of canals and understanding the origins of canal water quality are fundamental to designing improved management strategies to meet the requirements of the WFD. Results of this research, in combination with channel flow and water quality modelling, will be used to provide

  4. Equalization enhanced phase noise in Nyquist-spaced superchannel transmission systems using multi-channel digital back-propagation

    NASA Astrophysics Data System (ADS)

    Xu, Tianhua; Liga, Gabriele; Lavery, Domaniç; Thomsen, Benn C.; Savory, Seb J.; Killey, Robert I.; Bayvel, Polina

    2015-09-01

    Superchannel transmission spaced at the symbol rate, known as Nyquist spacing, has been demonstrated for effectively maximizing the optical communication channel capacity and spectral efficiency. However, the achievable capacity and reach of transmission systems using advanced modulation formats are affected by fibre nonlinearities and equalization enhanced phase noise (EEPN). Fibre nonlinearities can be effectively compensated using digital back-propagation (DBP). However EEPN which arises from the interaction between laser phase noise and dispersion cannot be efficiently mitigated, and can significantly degrade the performance of transmission systems. Here we report the first investigation of the origin and the impact of EEPN in Nyquist-spaced superchannel system, employing electronic dispersion compensation (EDC) and multi-channel DBP (MC-DBP). Analysis was carried out in a Nyquist-spaced 9-channel 32-Gbaud DP-64QAM transmission system. Results confirm that EEPN significantly degrades the performance of all sub-channels of the superchannel system and that the distortions are more severe for the outer sub-channels, both using EDC and MC-DBP. It is also found that the origin of EEPN depends on the relative position between the carrier phase recovery module and the EDC (or MC-DBP) module. Considering EEPN, diverse coding techniques and modulation formats have to be applied for optimizing different sub-channels in superchannel systems.

  5. Equalization enhanced phase noise in Nyquist-spaced superchannel transmission systems using multi-channel digital back-propagation

    PubMed Central

    Xu, Tianhua; Liga, Gabriele; Lavery, Domaniç; Thomsen, Benn C.; Savory, Seb J.; Killey, Robert I.; Bayvel, Polina

    2015-01-01

    Superchannel transmission spaced at the symbol rate, known as Nyquist spacing, has been demonstrated for effectively maximizing the optical communication channel capacity and spectral efficiency. However, the achievable capacity and reach of transmission systems using advanced modulation formats are affected by fibre nonlinearities and equalization enhanced phase noise (EEPN). Fibre nonlinearities can be effectively compensated using digital back-propagation (DBP). However EEPN which arises from the interaction between laser phase noise and dispersion cannot be efficiently mitigated, and can significantly degrade the performance of transmission systems. Here we report the first investigation of the origin and the impact of EEPN in Nyquist-spaced superchannel system, employing electronic dispersion compensation (EDC) and multi-channel DBP (MC-DBP). Analysis was carried out in a Nyquist-spaced 9-channel 32-Gbaud DP-64QAM transmission system. Results confirm that EEPN significantly degrades the performance of all sub-channels of the superchannel system and that the distortions are more severe for the outer sub-channels, both using EDC and MC-DBP. It is also found that the origin of EEPN depends on the relative position between the carrier phase recovery module and the EDC (or MC-DBP) module. Considering EEPN, diverse coding techniques and modulation formats have to be applied for optimizing different sub-channels in superchannel systems. PMID:26365422

  6. Traveling waves for the FitzHugh-Nagumo system on an infinite channel

    NASA Astrophysics Data System (ADS)

    Chen, Chao-Nien; Chen, Chiun-Chuan; Huang, Chih-Chiang

    2016-09-01

    We are concerned with the traveling wave solutions for the FitzHugh-Nagumo system on an infinite channel. Based on a variational formulation in which a non-local term depends on a parameter, the speed of a traveling wave can be selected out. Furthermore, to show the existence of a traveling wave solution with such a speed, we seek a minimizer subject to a constraint. In the way of solving the variational problem, we apply a truncation technique to the nonlocal term to obtain a minimizer located in a bounded invariant region.

  7. 71. VIEW OF STANDARD QUINTRON SYSTEMS, INC., 20CHANNEL COMMUNICATIONS PANEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    71. VIEW OF STANDARD QUINTRON SYSTEMS, INC., 20-CHANNEL COMMUNICATIONS PANEL (RIGHT BOTTOM); AMPLIFIER (RIGHT MIDDLE); AND SLAVE COMMUNICATIONS PANEL (LEFT BOTTOM). TOP OF RIGHT PANEL CONTAINS AN AM/FM RADIO RECIEVER THAT IS NOT RELATED TO THE SLC-3 COMMUNICATIONS NETWORK. THESE PANELS LOCATED IN THE CENTER OF THE LONG CONSOLE NEAR THE SOUTHEAST CORNER OF THE SLC-3E CONTROL ROOM. (See background of CA-133-1-A-56.) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Operations Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  8. Space communication system for compressed data with a concatenated Reed-Solomon-Viterbi coding channel

    NASA Technical Reports Server (NTRS)

    Rice, R. F.; Hilbert, E. E. (Inventor)

    1976-01-01

    A space communication system incorporating a concatenated Reed Solomon Viterbi coding channel is discussed for transmitting compressed and uncompressed data from a spacecraft to a data processing center on Earth. Imaging (and other) data are first compressed into source blocks which are then coded by a Reed Solomon coder and interleaver, followed by a convolutional encoder. The received data is first decoded by a Viterbi decoder, followed by a Reed Solomon decoder and deinterleaver. The output of the latter is then decompressed, based on the compression criteria used in compressing the data in the spacecraft. The decompressed data is processed to reconstruct an approximation of the original data-producing condition or images.

  9. Effect of channel size on sweet potato storage root enlargement in the Tuskegee University hydroponic nutrient film system

    NASA Technical Reports Server (NTRS)

    Morris, Carlton E.; Martinez, Edwin; Bonsi, C. K.; Mortley, Desmond G.; Hill, Walter A.; Ogbuehi, Cyriacus R.; Loretan, Phil A.

    1989-01-01

    The potential of the sweet potato as a food source for future long term manned space missions is being evaluated for NASA's Controlled Ecological Life Support Systems (CELSS) program. Sweet potatoes have been successfully grown in a specially designed Tuskegee University nutrient film technique (TU NFT) system. This hydroponic system yielded storage roots as high as 1790 g/plant fresh weight. In order to determine the effect of channel size on the yield of sweet potatoes, the width and depth of the growing channels were varied in two separate experiments. Widths were studied using the rectangular TU NFT channels with widths of 15 cm (6 in), 30 cm (12 in) and 45 cm (18 in). Channel depths of 5 cm (2 in), 10 cm (4 in), and 15 cm (6 in) were studied using a standard NASA fan shaped Biomass Production Chamber (BPC) channel. A comparison of preliminary results indicated that, except for storage root number, the growth and yield of sweet potatoes were not affected by channel width. Storage root yield was affected by channel depth although storage root number and foliage growth were not. Both experiments are being repeated.

  10. In Vivo Testing of A Low Noise 32-Channel Wireless Neural Recording System

    PubMed Central

    Yin, Ming; Lee, Seung Bae

    2013-01-01

    We present a 32-channel wireless implantable neural recording system-on-a-chip (SoC) that operates based on time division multiplexing (TDM) of pulse width modulated (PWM) samples with minimal substrate noise and interference. We have utilized analog-to-time conversion (ATC) on the transmitter and time-to-digital conversion (TDC) on the receiver to reduce the size and power consumption of the implantable unit by moving the digitization circuitry to the external unit. We have managed the TDM switching times such that no switching occurs during sensitive sampling onsets. The chip has been implemented in the AMI 0.5-μm standard CMOS process, occupying 3.3 × 3.0 mm2 and consuming 5.6 mW at ±1.5 V when all channels are active. The measured input referred noise for the entire system, including the receiver at 1 m distance, is only 4.9 μVrms from 1 Hz~10 kHz. Finally, in vivo testing results on rats have been presented to validate the full functionality of the system. PMID:19964005

  11. In vivo testing of a low noise 32-channel wireless neural recording system.

    PubMed

    Yin, Ming; Lee, Seung Bae; Ghovanloo, Maysam

    2009-01-01

    We present a 32-channel wireless implantable neural recording system-on-a-chip (SoC) that operates based on time division multiplexing (TDM) of pulse width modulated (PWM) samples with minimal substrate noise and interference. We have utilized analog-to-time conversion (ATC) on the transmitter and time-to-digital conversion (TDC) on the receiver to reduce the size and power consumption of the implantable unit by moving the digitization circuitry to the external unit. We have managed the TDM switching times such that no switching occurs during sensitive sampling onsets. The chip has been implemented in the AMI 0.5-microm standard CMOS process, occupying 3.3 x 3.0 mm(2) and consuming 5.6 mW at +/-1.5 V when all channels are active. The measured input referred noise for the entire system, including the receiver at 1 m distance, is only 4.9 microV(rms) from 1 Hz approximately 10 kHz. Finally, in vivo testing results on rats have been presented to validate the full functionality of the system. PMID:19964005

  12. Equalization in redundant channels

    NASA Technical Reports Server (NTRS)

    Tulpule, Bhalchandra R. (Inventor); Collins, Robert E. (Inventor); Cominelli, Donald F. (Inventor); O'Neill, Richard D. (Inventor)

    1988-01-01

    A miscomparison between a channel's configuration data base and a voted system configuration data base in a redundant channel system having identically operating, frame synchronous channels triggers autoequalization of the channel's historical signal data bases in a hierarchical, chronological manner with that of a correctly operating channel. After equalization, symmetrization of the channel's configuration data base with that of the system permits upgrading of the previously degraded channel to full redundancy. An externally provided equalization command, e.g., manually actuated, can also trigger equalization.

  13. Do Voltage-Dependent K^+ Channels Require Ca2+? A Critical Test Employing a Heterologous Expression System

    NASA Astrophysics Data System (ADS)

    Armstrong, Clay M.; Miller, Christopher

    1990-10-01

    Removal of Ca2+ from the solution bathing neurons is known in many cases to alter the gating properties of voltage-dependent K^+ channels and to induce a large, nonselective "leak" conductance. We used a heterologous expression system to test whether the leak conductance observed in neurons is mediated by voltage-dependent K^+ channels in an altered, debased conformation. Voltage-dependent K^+ channels were expressed in an insect cell line infected with a recombinant baculovirus carrying the cDNA for Drosophila Shaker "A-type" K^+ channels. These expressed channels respond to low Ca2+ identically to voltage-dependent K^+ channels in native neuronal membranes; upon removal of external Ca2+, Shaker K^+ currents disappear and are replaced by a steady, nonselective leak conductance. However, control cells devoid of Shaker channels were free of any voltage-dependent conductances and did not generate a leak when external Ca2+ was removed. These results show that Ca2+ is essential for proper function of voltage-dependent K^+ channels and is required to stabilize the native conformations of these membrane proteins.

  14. The possible role of Coriolis forces in structuring large-scale sinuous patterns of submarine channel-levee systems.

    PubMed

    Wells, Mathew; Cossu, Remo

    2013-12-13

    Submarine channel-levee systems are among the largest sedimentary structures on the ocean floor. These channels have a sinuous pattern and are the main conduits for turbidity currents to transport sediment to the deep ocean. Recent observations have shown that their sinuosity decreases strongly with latitude, with high-latitude channels being much straighter than similar channels near the Equator. One possible explanation is that Coriolis forces laterally deflect turbidity currents so that at high Northern latitudes both the density interface and the downstream velocity maximum are deflected to the right-hand side of the channel (looking downstream). The shift in the velocity field can change the locations of erosion and deposition and introduce an asymmetry between left- and right-turning bends. The importance of Coriolis forces is defined by two Rossby numbers, Ro(W) = U/Wf and Ro(R) = U/Rf, where U is the mean downstream velocity, W is the width of the channel, R is the radius of curvature and f is the Coriolis parameter. In a bending channel, the density interface is flat when Ro(R) - -1, and Coriolis forces start to shift the velocity maximum when [Row] < 5. We review recent experimental and field observations and describe how Coriolis forces could lead to straighter channels at high latitudes. PMID:24471273

  15. Optically synchronized dual-channel terahertz signals for high-performance transmitter/receiver system

    NASA Astrophysics Data System (ADS)

    Shimizu, Naofumi; Oh, Kyoung-Hwan; Kohjiro, Satoshi; Kikuchi, Ken'ichi; Wakatsuki, Atsushi; Kukutsu, Naoya; Kado, Yuichi

    2010-02-01

    We developed a high-sweeping-speed optically synchronized dual-channel terahertz signal generator, in which the frequency difference between the two terahertz signals is independent of the frequency of the terahertz signals themselves. This feature is essential for heterodyne detection of terahertz signals with various frequencies. With this generator, a frequency-sweepable terahertz transmitter (Tx)/receiver (Rx) system with a wide dynamic range can be realized without sacrificing the high frequency-sweeping speed. Absorption line measurements for water vapor and nitrous oxide show that the developed Tx/Rx system can detect gas absorption with the optical depth of 0.04 or less. This result indicates the potential of the system as a remote gas sensor and gas analyzer.

  16. [Multi-channel data collection and visualization system for intramyocardial electrograms].

    PubMed

    Kastner, P; Wimmer, W; Hutten, H

    2000-11-01

    The aim of the project was to develop a multichannel data acquisition system for the recording and visualisation of intramyocardial electrograms (IEGM) from both the spontaneously beating and the artificially paced heart. Signal processing comprises multi-step amplification, filtering (0.05-800 Hz), and AD conversion (12 Bit max. 6.25 kHz). IEGMs can be obtained either in unipolar or bipolar mode. Stimulation of the heart is achieved by an incorporated programmable dual-chamber pacemaker that can be selectively switched to the input channels. A LabView-based graphical user interface permits the programming of all system parameters via a microcontroller, and supports data acquisition and visualisation. The system can be used in animal experiments to monitor the spread of excitation across the heart, to measure propagation velocity, or to measure the impact of drugs and pathological changes on the morphology of IEGMs. PMID:11155534

  17. MONSTIR II: A 32-channel, multispectral, time-resolved optical tomography system for neonatal brain imaging

    SciTech Connect

    Cooper, Robert J. Magee, Elliott; Everdell, Nick; Magazov, Salavat; Varela, Marta; Airantzis, Dimitrios; Gibson, Adam P.; Hebden, Jeremy C.

    2014-05-15

    We detail the design, construction and performance of the second generation UCL time-resolved optical tomography system, known as MONSTIR II. Intended primarily for the study of the newborn brain, the system employs 32 source fibres that sequentially transmit picosecond pulses of light at any four wavelengths between 650 and 900 nm. The 32 detector channels each contain an independent photo-multiplier tube and temporally correlated photon-counting electronics that allow the photon transit time between each source and each detector position to be measured with high temporal resolution. The system's response time, temporal stability, cross-talk, and spectral characteristics are reported. The efficacy of MONSTIR II is demonstrated by performing multi-spectral imaging of a simple phantom.

  18. MONSTIR II: a 32-channel, multispectral, time-resolved optical tomography system for neonatal brain imaging.

    PubMed

    Cooper, Robert J; Magee, Elliott; Everdell, Nick; Magazov, Salavat; Varela, Marta; Airantzis, Dimitrios; Gibson, Adam P; Hebden, Jeremy C

    2014-05-01

    We detail the design, construction and performance of the second generation UCL time-resolved optical tomography system, known as MONSTIR II. Intended primarily for the study of the newborn brain, the system employs 32 source fibres that sequentially transmit picosecond pulses of light at any four wavelengths between 650 and 900 nm. The 32 detector channels each contain an independent photo-multiplier tube and temporally correlated photon-counting electronics that allow the photon transit time between each source and each detector position to be measured with high temporal resolution. The system's response time, temporal stability, cross-talk, and spectral characteristics are reported. The efficacy of MONSTIR II is demonstrated by performing multi-spectral imaging of a simple phantom. PMID:24880351

  19. Multi-Channel Magnetocardiogardiography System Based on Low-Tc SQUIDs in an Unshielded Environment

    NASA Astrophysics Data System (ADS)

    Kong, Xiangyan; Zhang, Shulin; Wang, Yongliang; Zeng, Jia; Xie, Xiaoming

    Magnetocardiography (MCG) using superconducting quantum interference devices (SQUIDs) is a new medical diagnostic tool measuring biomagnetic signals that are generated by the electrical activity of the human heart. This technique is completely passive, contactless, and it has an advantage in the early diagnosis of heart diseases. We developed the first unshielded four-channel MCG system based on low-Tc DC SQUIDs in China. Instead of using a costly magnetically shielded room, the environmental noise suppression was realized by using second-order gradiometers and three-axis reference magnetometer. The measured magnetic field resolution of the system is better than 1 pT, and multi-cycle human heart signals can be recorded directly. Also, with the infrared positioning system, 48 points data collection can be realized by moving the non-magnetic bed nine times.

  20. Multiscale bloom dynamics from a high frequency autonomous measurement system in the Eastern English Channel

    NASA Astrophysics Data System (ADS)

    Derot, Jonathan; Schmitt, François; Gentilhomme, Valérie

    2014-05-01

    We consider here a dataset from an Eulerian automated system, located on the coastal area of the French side of the English Channel (Boulogne-sur-Mer), called MAREL Carnot, operated by IFREMER (France). This system records more than 15 physico-chemical parameters at 20 minutes intervals, and at the constant depth of -1,5m whatever the tidal range. Our study focuses on the period 2004 to 2011. The objective of this study is to have a better understanding of the bloom fluorescence multiscale dynamics, as regards the coastal area of English Channel and possible influence of temperature on this dynamics. Annual blooms are visible, superposed to multiscale fluctuations. The probability density function (PDF) of the fluorescence time series very nicely obeys a power law with slope -2. The PDF for annual portions obeys also power laws, with slopes which are related to the annual average. Empirical mode decomposition (EMD) is used to study the dynamics and display the power spectrum, which will be linked with these dynamics. EMD method is also used to extract a trend and isolate the blooms from the high frequency dynamics. We show that the high frequency part of the fluorescence dynamics has a very large variance during bloom events, compared to normal conditions. We also show that there is a link between the mean winter temperature and the strength of bloom next spring. These results contribute to statistically characterize the bloom dynamics and extract some possible universal relations. Keywords: English Channel; Autonomous monitoring; Power spectra; EMD method; Probability density functions; Power laws.

  1. An efficient system for reliably transmitting image and video data over low bit rate noisy channels

    NASA Technical Reports Server (NTRS)

    Costello, Daniel J., Jr.; Huang, Y. F.; Stevenson, Robert L.

    1994-01-01

    This research project is intended to develop an efficient system for reliably transmitting image and video data over low bit rate noisy channels. The basic ideas behind the proposed approach are the following: employ statistical-based image modeling to facilitate pre- and post-processing and error detection, use spare redundancy that the source compression did not remove to add robustness, and implement coded modulation to improve bandwidth efficiency and noise rejection. Over the last six months, progress has been made on various aspects of the project. Through our studies of the integrated system, a list-based iterative Trellis decoder has been developed. The decoder accepts feedback from a post-processor which can detect channel errors in the reconstructed image. The error detection is based on the Huber Markov random field image model for the compressed image. The compression scheme used here is that of JPEG (Joint Photographic Experts Group). Experiments were performed and the results are quite encouraging. The principal ideas here are extendable to other compression techniques. In addition, research was also performed on unequal error protection channel coding, subband vector quantization as a means of source coding, and post processing for reducing coding artifacts. Our studies on unequal error protection (UEP) coding for image transmission focused on examining the properties of the UEP capabilities of convolutional codes. The investigation of subband vector quantization employed a wavelet transform with special emphasis on exploiting interband redundancy. The outcome of this investigation included the development of three algorithms for subband vector quantization. The reduction of transform coding artifacts was studied with the aid of a non-Gaussian Markov random field model. This results in improved image decompression. These studies are summarized and the technical papers included in the appendices.

  2. The interaction between deepwater channel systems and growing thrusts and folds, toe-thrust region of the deepwater Niger Delta

    NASA Astrophysics Data System (ADS)

    Jolly, Byami; Whittaker, Alex; Lonergan, Lidia

    2015-04-01

    Gravity-driven seaward-verging thrusts, landward-verging back-thrusts and associated folds often characterize the slope and deepwater settings of passive margins. These structures, found in the 'toe-thrust' region of the system, exert a significant control on sediment gravity flows because they create and determine the location and configuration of sediment depocentres and transport systems. Consequently, a quantitative understanding of the interaction between sediment gravity flows and seabed topography is required to understand these systems effectively. Here we make quantitative measurements of the geomorphic response of submarine channels to growing tectonic structures with the aim of providing new constraints on the long-term erosional dynamics of submarine channel systems. This study exploits 3D seismic data in the outer toe-thrust region of the deepwater Niger Delta to analyze the interaction between Plio-Pleistocene channel systems and actively growing folds and thrusts. We mapped folds and thrusts from the seismic data and we used this data to reconstruct the history of fold growth. We then used the sea-bed seismic horizon to build a 50 m resolution Digital Elevation Model (DEM) of the sea floor in Arc-GIS. We extracted channel long- profiles across growing structures from the DEM, and made measurements of channel geometries at regular intervals along the channel length. This information was used to infer morphodyanamic processes that sculpted the channel systems through time, and to estimate the bed shear stresses and fluid velocities of typical flow events. The bathymetric long profiles of these channels are relatively linear with concavity that range from -0.08 to -0.34, and an average gradient of ~1o. Actively growing thrusts are typically associated with a local steepening in channel gradient by a factor of up to 3, and this effect extends 0.5 - 2 km upstream of the thrust. Within these knickzones, channel incision increases by approximately by a

  3. Channel nut tool

    DOEpatents

    Olson, Marvin

    2016-01-12

    A method, system, and apparatus for installing channel nuts includes a shank, a handle formed on a first end of a shank, and an end piece with a threaded shaft configured to receive a channel nut formed on the second end of the shaft. The tool can be used to insert or remove a channel nut in a channel framing system and then removed from the channel nut.

  4. ARA 290 relieves pathophysiological pain by targeting TRPV1 channel: Integration between immune system and nociception.

    PubMed

    Zhang, Wenjia; Yu, Guanling; Zhang, Mengyuan

    2016-02-01

    ARA 290 is an erythropoietin-derived polypeptide that possesses analgesic and tissue protective effect in many diseases such as diabetes and cancer. The analgesic effect of ARA 290 is mediated by its anti-inflammatory and immunomodulatory functions, or more specifically, by targeting the innate repair receptor (IRR) to down-regulate inflammation to alleviate neuropathic pain. However, whether other mechanisms or pathways are involved in ARA 290-mediated analgesic effect remains elusive. In this study, we are particularly interested in whether ARA 290 could directly target peripheral nociceptors by blocking or influencing receptors in pain sensation. Using calcium imaging, cell culture and behavioral tests, we demonstrated that ARA 290 was able to specifically inhibit TRPV1 channel activity, and relieve the mechanical hypersensitivity induced by capsaicin. Our study suggested that ARA 290 could potentially function as a novel antagonist for TRPV1 channel. This finding would not only contribute to the development of new pain treatment using ARA 290, but also help to improve our understanding of the integration between the immune system and the peripheral nervous system. PMID:26774587

  5. Joint Symbol Timing and CFO Estimation for OFDM/OQAM Systems in Multipath Channels

    NASA Astrophysics Data System (ADS)

    Fusco, Tilde; Petrella, Angelo; Tanda, Mario

    2009-12-01

    The problem of data-aided synchronization for orthogonal frequency division multiplexing (OFDM) systems based on offset quadrature amplitude modulation (OQAM) in multipath channels is considered. In particular, the joint maximum-likelihood (ML) estimator for carrier-frequency offset (CFO), amplitudes, phases, and delays, exploiting a short known preamble, is derived. The ML estimators for phases and amplitudes are in closed form. Moreover, under the assumption that the CFO is sufficiently small, a closed form approximate ML (AML) CFO estimator is obtained. By exploiting the obtained closed form solutions a cost function whose peaks provide an estimate of the delays is derived. In particular, the symbol timing (i.e., the delay of the first multipath component) is obtained by considering the smallest estimated delay. The performance of the proposed joint AML estimator is assessed via computer simulations and compared with that achieved by the joint AML estimator designed for AWGN channel and that achieved by a previously derived joint estimator for OFDM systems.

  6. Ultrafast STR Separations on Short-Channel Microfluidic Systems for Forensic Screening and Genotyping.

    PubMed

    Aboud, Maurice J; Gassmann, Marcus; McCord, Bruce

    2015-09-01

    There are situations in which it is important to quickly and positively identify an individual. Examples include suspects detained in the neighborhood of a bombing or terrorist incident, individuals detained attempting to enter or leave the country, and victims of mass disasters. Systems utilized for these purposes must be fast, portable, and easy to maintain. DNA typing methods provide the best biometric information yielding identity, kinship, and geographical origin, but they are not portable and rapid. This study details the development of a portable short-channel microfluidic device based on a modified Agilent 2100 bioanalyzer for applications in forensic genomics. The system utilizes a denaturing polymer matrix with dual-channel laser-induced fluorescence and is capable of producing a genotype in 80 sec. The device was tested for precision and resolution using an allelic ladder created from 6 short tandem repeat (STR) loci and a sex marker (amelogenin). The results demonstrated a precision of 0.09-0.21 bp over the entire size range and resolution values from 2.5 to 4.1 bp. Overall, the results demonstrate the chip provides a portable, rapid, and precise method for screening amplified short tandem repeats and human identification screening. PMID:26280913

  7. Real-time system design environment for multi-channel high-speed data acquisition system and pattern recognition

    SciTech Connect

    Crosetto, Dario B.

    1999-06-17

    The Design Real-Time 2.0 software environment provides the user with a set of tools to create a real-time fully programmable system which can sustain a rate of several MHz from multi-channel inputs, can extend processing time in a pipeline stage and can provide a result within a few hundred ns. The tool set allows the user to (a) create applications of different sizes with different throughput and filtering algorithms; (b) select the processor speed, internal bus width, lookup tables, number of input and output result bits for each set of data received at each channel for each algorithm execution; (c) simulate a specific parallel-processing system for a given algorithm on different sets of data; (d) monitor the system in real time via an RS232 interface; (e) create a hardware component (FPGA or ASIC) by means of interfacing to the Electronic Design Automation (EDA) tools. The advantage of these tools is that of allowing simulation, before construction, of an entire programmable high-speed data acquisition and processing system, and selection of the processor speed, bus width and real-time algorithm which is most cost effective for a specific application where general-purpose processors fail in speed and performance. Benefits derived from the use of the novel architecture and cost comparisons with respect to similar designs are also provided.

  8. SER Analysis of MPPM-Coded MIMO-FSO System over Uncorrelated and Correlated Gamma-Gamma Atmospheric Turbulence Channels

    NASA Astrophysics Data System (ADS)

    Khallaf, Haitham S.; Garrido-Balsells, José M.; Shalaby, Hossam M. H.; Sampei, Seiichi

    2015-12-01

    The performance of multiple-input multiple-output free space optical (MIMO-FSO) communication systems, that adopt multipulse pulse position modulation (MPPM) techniques, is analyzed. Both exact and approximate symbol-error rates (SERs) are derived for both cases of uncorrelated and correlated channels. The effects of background noise, receiver shot-noise, and atmospheric turbulence are taken into consideration in our analysis. The random fluctuations of the received optical irradiance, produced by the atmospheric turbulence, is modeled by the widely used gamma-gamma statistical distribution. Uncorrelated MIMO channels are modeled by the α-μ distribution. A closed-form expression for the probability density function of the optical received irradiance is derived for the case of correlated MIMO channels. Using our analytical expressions, the degradation of the system performance with the increment of the correlation coefficients between MIMO channels is corroborated.

  9. Structure of the voltage-dependent potassium channel is highly conserved from Drosophila to vertebrate central nervous systems.

    PubMed Central

    Baumann, A; Grupe, A; Ackermann, A; Pongs, O

    1988-01-01

    Voltage-sensitive potassium channels are found in vertebrate and invertebrate central nervous systems. We have isolated a rat brain cDNA by cross-hybridization with a probe of the Drosophila Shaker gene complex. Structural conservation of domains of the deduced protein indicate that the rat brain cDNA encodes a voltage-sensitive potassium channel. Of the deduced amino acid sequence, 82% is homologous to the Drosophila Shaker protein indicating that voltage-sensitive potassium channels have been highly conserved during evolution. Selective pressure was highest on sequences facing the intracellular side and on proposed transmembrane segments S4-S6, suggesting that these domains are crucial for voltage-dependent potassium channel function. The corresponding rat mRNA apparently belongs to a family of mRNA molecules which are preferentially expressed in the central nervous system. Images PMID:3191911

  10. Terrestrial analogs to lunar sinuous rilles - Kauhako Crater and channel, Kalaupapa, Molokai, and other Hawaiian lava conduit systems

    NASA Technical Reports Server (NTRS)

    Coombs, C. R.; Hawke, B. R.; Wilson, L.

    1990-01-01

    Two source vents, one explosive and one effusive erupted to form a cinder cone and low lava shield that together compose the Kalaupapa peninsula of Molokai, Hawaii, A 50-100-m-wide channel/tube system extends 2.3 km northward from kauhako crater in the center of the shield. Based on modeling, a volume of up to about 0.2 cu km of lava erupted at a rate of 260 cu m/sec to flow through the Kauhako conduit system in one of the last eruptive episodes on the peninsula. Channel downcutting by thermal erosion occurred at a rate of about 10 micron/sec to help form the 30-m-deep conduit. Two smaller, secondary tube systems formed east of the main lava channel/tube. Several other lava conduit systems on the islands of Oahu and Hawaii were also compared to the Kauhako and lunar sinuous rille systems. These other lava conduits include Whittington, Kupaianaha, and Mauna Ulu lava tubes. Morphologically, the Hawaiian tube systems studied are very similar to lunar sinuous rilles in that they have deep head craters, sinuous channels, and gentle slopes. Thermal erosion is postulated to be an important factor in the formation of these terrestrial channel systems and by analogy is inferred to be an important process involved in the formation of lunar sinuous rilles.

  11. Application of a four-channel vibrometer system for detection of arterial stiffness

    NASA Astrophysics Data System (ADS)

    Campo, Adriaan; Waz, Adam; Dudzik, Grzegorz; Dirckx, Joris; Abramski, Krzysztof

    2016-06-01

    Cardiovascular diseases (CD) are the most important cause of death in the world and their prevalence is only rising. A significant aspect in the etiology of CD is the stiffening of the large arteries (arteriosclerosis) and plaque formation (atherosclerosis) in the common carotid artery (CCA) in the neck. As shown by increasing evidence, both conditions can be detected by assessing pulse wave velocity (PWV) in the CCA, and several approaches allow local detection of PWV, including ultrasound (US) and magnetic resonance imaging (MRI). In previous studies, laser Doppler vibrometry (LDV) was introduced as an approach to assess arterial stiffness. In the present work, a new, compact four-channel LDV system is used for PWV detection in four phantom arteries mimicking real life CCA conditions. The high sensitivity of the LDV system allowed PWV to be assessed, and even local changes in phantom architecture could be detected. This method has potential for cardiovascular screening, as it allows arteriosclerosis assessment and plaque detection.

  12. Low-power high-resolution 32-channel neural recording system.

    PubMed

    Yun, Xiao; Kim, Donghwi; Stanaćević, Milutin; Mainen, Zachary

    2007-01-01

    A design of low-power 32-channel neural recording system with on-chip high-resolution A/D converters is presented. A neural front-end including low-noise fully differential pre-amplifier, gain stage, and buffer consumes only 56 mu W. Two 13-bits extended counting A/D converters running at 512KHz sampling rate are integrated with 32 neural front-ends on a chip. The experimental prototype was designed in 0.6 microm CMOS process. With a 3.3V power supply, total power consumption of a chip is 22mW and the whole system occupies an area of 3mm x 3mm. PMID:18002470

  13. SER performance analysis of MPPM FSO system with three decision thresholds over exponentiated Weibull fading channels

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Yang, Bensheng; Guo, Lixin; Shang, Tao

    2015-11-01

    In this work, the symbol error rate (SER) performance of the multiple pulse position modulation (MPPM) based free-space optical communication (FSO) system with three different decision thresholds, fixed decision threshold (FDT), optimized decision threshold (ODT) and dynamic decision threshold (DDT) over exponentiated Weibull (EW) fading channels has been investigated in detail. The effects of aperture averaging on each decision threshold under weak-to-strong turbulence conditions are further studied and compared. The closed-form SER expressions for three thresholds derived with the help of generalized Gauss-Laguerre quadrature rule are verified by the Monte Carlo simulations. This work is helpful for the design of receivers for FSO communication systems.

  14. SINR Analysis of Hexagonal Multicarrier Transmission Systems in the Presence of Insufficient Synchronization for Doubly Dispersive Channel

    NASA Astrophysics Data System (ADS)

    Xu, Kui; Xu, Youyun; Zhang, Dongmei

    2011-07-01

    This paper analyzes the effect of the insufficient synchronization (carrier frequency offset, timing offset) on hexagonal multicarrier transmission (HMT) systems for doubly dispersive channel. Exact SINR and demodulated symbol expressions for HMT systems in the presence of insufficient synchronization transmission conditions over doubly dispersive channel with exponential delay power profile and U-shape Doppler power spectrum and uniform delay power profile and uniform Doppler power spectrum are derived, respectively. Theoretical analysis shows that similar degradations on symbol amplitude and phase caused by insufficient synchronization are incurred as in traditional cyclic-prefix orthogonal frequency division multiplexing (CP-OFDM) transmission. HMT systems outperform traditional OFDM systems with respect to signal to interference-plus-noise-ratio (SINR) against inter-symbol interference (ISI) and inter-carrier interference (ICI) caused by insufficient synchronization and doubly dispersive(DD) channel. The BER performance of the HMT systems using Monte Carlo simulation match with the conclusion given by the proposed exact SINR expression.

  15. 47 CFR 90.721 - Other channels available for non-nationwide systems in the 220-222 MHz band.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) Channel Nos. A EA 2 and 13 B EA 3 and 16 C EA 5 and 18 D EA 8 and 19 E EA 171-180 F REAG 1, 6, and 11 G...-nationwide systems in the 220-222 MHz band. (a) The channel groups listed in the following Table are... equivalent or greater efficiency for non-commercial or commercial operations. Table 1—Phase I Trunked...

  16. 47 CFR 90.721 - Other channels available for non-nationwide systems in the 220-222 MHz band.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Channel Nos. A EA 2 and 13 B EA 3 and 16 C EA 5 and 18 D EA 8 and 19 E EA 171-180 F REAG 1, 6, and 11 G...-nationwide systems in the 220-222 MHz band. (a) The channel groups listed in the following Table are... equivalent or greater efficiency for non-commercial or commercial operations. Table 1—Phase I Trunked...

  17. Morphology of Red Creek, Wyoming, an arid-region anastomosing channel system

    USGS Publications Warehouse

    Schumann, R.R.

    1989-01-01

    The narrow, deep, and sinuous main channel is flanked by anastomosing flood channels, or anabranches. Most anabranches are initiated at meander bends. The primary mechanism of anabranch initiation is avulsion during overbank floods. -from Author

  18. A comprehensive study of channel estimation for WBAN-based healthcare systems: feasibility of using multiband UWB.

    PubMed

    Islam, S M Riazul; Kwak, Kyung Sup

    2012-06-01

    Wireless personal area network (WPAN) is an emerging in wireless technology for short range indoor and outdoor communication applications. A more specific category of WPAN is the wireless body area network (WBAN) used for health monitoring. On the other hand, multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) comes with a number of desirable features at the physical layer for wireless communications, for example, very high data rate. One big challenge in adoption of multiband UWB in WBAN is the fact that channel estimation becomes difficult under the constraint of extremely low transmission power. Moreover, the heterogeneous environment of WBAN causes a dense multipath wireless channel. Therefore, effective channel estimation is required in the receiver of WBAN-based healthcare system that uses multiband UWB. In this paper, we first outline the MB-OFDM UWB system. Then, we present an overview of channel estimation techniques proposed/investigated for multiband UWB communications with emphasis on their strengths and weaknesses. Useful suggestions are given to overcome the weaknesses so that these methods can be particularly useful for WBAN channels. Also, we analyze the comparative performances of the techniques using computer simulation in order to find the energy-efficient channel estimation methods for WBAN-based healthcare systems. PMID:21046206

  19. Iterative Frequency-Domain Channel Estimation and Equalization for Ultra-Wideband Systems with Short Cyclic Prefix

    NASA Astrophysics Data System (ADS)

    Bahçeci, Salim; Koca, Mutlu

    2010-12-01

    In impulse radio ultra-wideband (IR-UWB) systems where the channel lengths are on the order of a few hundred taps, conventional use of frequency-domain (FD) processing for channel estimation and equalization may not be feasible because the need to add a cyclic prefix (CP) to each block causes a significant reduction in the spectral efficiency. On the other hand, using no or short CP causes the interblock interference (IBI) and thus degradation in the receiver performance. Therefore, in order to utilize FD receiver processing UWB systems without a significant loss in the spectral efficiency and the performance, IBI cancellation mechanisms are needed in both the channel estimation and equalization operations. For this reason, in this paper, we consider the joint FD channel estimation and equalization for IR-UWB systems with short cyclic prefix (CP) and propose a novel iterative receiver employing soft IBI estimation and cancellation within both its FD channel estimator and FD equalizer components. We show by simulation results that the proposed FD receiver attains performances close to that of the full CP case in both line-of-sight (LOS) and non-line-of-sight (NLOS) UWB channels after only a few iterations.

  20. A Wireless Multi-Channel Recording System for Freely Behaving Mice and Rats

    PubMed Central

    Holtzman, Tahl; Ruther, Patrick; Dalley, Jeffrey W.; Lopez, Alberto; Rossi, Mark A.; Barter, Joseph W.; Salas-Meza, Daniel; Herwik, Stanislav; Holzhammer, Tobias; Morizio, James; Yin, Henry H.

    2011-01-01

    To understand the neural basis of behavior, it is necessary to record brain activity in freely moving animals. Advances in implantable multi-electrode array technology have enabled researchers to record the activity of neuronal ensembles from multiple brain regions. The full potential of this approach is currently limited by reliance on cable tethers, with bundles of wires connecting the implanted electrodes to the data acquisition system while impeding the natural behavior of the animal. To overcome these limitations, here we introduce a multi-channel wireless headstage system designed for small animals such as rats and mice. A variety of single unit and local field potential signals were recorded from the dorsal striatum and substantia nigra in mice and the ventral striatum and prefrontal cortex simultaneously in rats. This wireless system could be interfaced with commercially available data acquisition systems, and the signals obtained were comparable in quality to those acquired using cable tethers. On account of its small size, light weight, and rechargeable battery, this wireless headstage system is suitable for studying the neural basis of natural behavior, eliminating the need for wires, commutators, and other limitations associated with traditional tethered recording systems. PMID:21765934

  1. Operational experience with a long-range, multi-channel acoustic telemetry system

    SciTech Connect

    High, G.; Carman, R.J.

    1985-01-01

    This paper describes the design, installation, and long-term operation of a modular subsea acoustic data acquisition system in the Duncan/Argyll field, North Sea. This equipment is presently providing on-demand pressure data from eight satellite locations at ranges in excess of seven kilometres. The discussion covers the use of in-field noise measurements for optimizing system performance in a high noise environment. Two main sections cover firstly platform installation and seabed installation of the subsea transceiver. Secondly at the remote wellhead locations, the acoustic transponders are described. Cost factors, as compared with hardwired or diver-monitored data acquisition systems are discussed. Modular design permits convenient addition of other data channels and/or extra remote subsea units. The surface equipment installed at the platform is software controlled so that display and data logging can be configured according to operator needs. Variations of the same basis system are discussed, as currently in use for subsea pipeline valve actuation, and submersible flowline tow-out instrumentation. Results of several years of operational experience in various offshore applications give confidence that, when properly considered in system design, an acoustic telemetry system can function reliably at useful ranges in the offshore environment.

  2. A multi-channel telemetry system for brain microstimulation in freely roaming animals.

    PubMed

    Xu, Shaohua; Talwar, Sanjiv K; Hawley, Emerson S; Li, Lei; Chapin, John K

    2004-02-15

    A system is described that enables an experimenter to remotely deliver electrical pulse train stimuli to multiple different locations in the brains of freely moving rats. The system consists of two separate components: a transmitter base station that is controlled by a PC operator, and a receiver-microprocessor integrated pack worn on the back of the animals and which connects to suitably implanted brain locations. The backpack is small and light so that small animal subjects can easily carry it. Under remote command from the PC the backpack can be configured to provide biphasic pulse trains of arbitrarily specified parameters. A feature of the system is that it generates precise brain-stimulation behavioral effects using the direct constant-voltage TTL output of the backpack microprocessor. The system performs with high fidelity even in complex environments over a distance of about 300 m. Rat self-stimulation tests showed that this system produced the same behavioral responses as a conventional constant-current stimulator. This system enables a variety of multi-channel brain stimulation experiments in freely moving animals. We have employed it to develop a new animal behavior model ("virtual" conditioning) for the neurophysiological study of spatial learning, in which a rat can be accurately guided to navigate various terrains. PMID:14757345

  3. Surface current patterns in the Ibiza Channel with the use of High Frequency (HF) Radar system

    NASA Astrophysics Data System (ADS)

    Lana, Arancha; Fernández, Vicente; Troupin, Charles; Pascual, Ananda; Orfila, Alejandro; Tintoré, Joaquín

    2014-05-01

    The Ibiza Channel located between the East Coast of the Iberian Peninsula, and the West Coast of Ibiza, at the Balearic Islands, is a well-known biodiversity hot spot. This area is relevant due to the interaction of water masses coming from the Atlantic Ocean - ascending through the Iberian Peninsula coast - with the older Atlantic waters descending from the Gulf of Lion. In 2012, the installation of Coastal HF Radar in the area provides valuable information for the study of the surface transport along the channel. The Coastal HF Radar operates since June 2012, and provides hourly surface current maps with a spatial resolution of approximately 3 km and a range reaching up to 70 km offshore. The instrument forms part of a monitoring multi-platform system, which is completed with satellite-derived data, gliders, modelling and fixed and lagrangian buoys. All HF Radar data are processed with standard quality control methods. Drifter velocity obtained from lagrangian buoys for two oceanographic campaigns, satellite-derived data and currentmeter data from a fixed buoy in the Ibiza Channel are used to validate the HF Radar data. All surface current data are used to perform a spectrum analysis in order to show the physical processes, at the main temporal periods. The contribution of the different temporal scales to the total Kinetic Energy has been analysed for the first time at different seasonal intervals. This served to evaluate the energetic importance of the different components of the surface currents. The inertial currents have a lower contribution to the total KE during winter, compared with the summer period. Besides, the spatial distribution of the inertial component to the total KE varies seasonally, and according to the bathymetry of the area. The low-pass (sub-inertial) filtered HF Radar currents show a predominant northern current during the summer months in the channel, and a mean southern current during the winter period. These results are discussed and

  4. Microfabricated channel array electrophoresis for characterization and screening of enzymes using RGS-G protein interactions as a model system.

    PubMed

    Pei, Jian; Dishinger, John F; Roman, David L; Rungwanitcha, Chetwana; Neubig, Richard R; Kennedy, Robert T

    2008-07-01

    A microfluidic chip consisting of parallel channels designed for rapid electrophoretic enzyme assays was developed. Radial arrangement of channels and a common waste channel allowed chips with 16 and 36 electrophoresis units to be fabricated on a 7.62 x 7.62 cm(2) glass substrate. Fluorescence detection was achieved using a Xe arc lamp source and commercial charge-coupled device (CCD) camera to image migrating analyte zones in individual channels. Chip performance was evaluated by performing electrophoretic assays for G protein GTPase activity on chip using BODIPY-GTP as enzyme substrate. A 16-channel design proved to be useful in extracting kinetic information by allowing serial electrophoretic assays from 16 different enzyme reaction mixtures at 20 s intervals in parallel. This system was used to rapidly determine enzyme concentrations, optimal enzymatic reaction conditions, and Michaelis-Menten constants. A chip with 36 channels was used for screening for modulators of the G protein-RGS protein interaction by assaying the amount of product formed in enzyme reaction mixtures that contained test compounds. Thirty-six electrophoretic assays were performed in 30 s suggesting the potential throughput up to 4320 assays/h with appropriate sample handling procedures. Both designs showed excellent reproducibility of peak migration time and peak area. Relative standard deviations of normalized peak area of enzymatic product BODIPY-GDP were 5% and 11%, respectively, in the 16- and 36-channel designs. PMID:18465881

  5. Stratigraphic evolution of a long-lived submarine channel system in the Late Cretaceous Nanaimo Group, British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Bain, Heather A.; Hubbard, Stephen M.

    2016-05-01

    Submarine canyons and slope channel systems are important conveyers of sediment from uplifted catchments to oceanic sedimentary sinks. Long-lived conduits can be established through deep incision of submarine canyons, with bathymetric relief of hundreds of meters to greater than a kilometer in many instances. Alternatively, a combination of erosion of the continental slope and aggradation of levees can yield a broadly comparable stratigraphic product through evolution of channels with more subdued bathymetric relief. Despite differences in formative geomorphic elements on the paleo-seafloor, differentiating the stratigraphic architecture amongst these systems is challenging, particularly in outcrop datasets. Accurate stratigraphic interpretation has significant implications for understanding the frequency and magnitude of controlling processes such as mountain building and denudation or eustatic sea-level fluctuations. In this study, deep-water channel strata of the Late Cretaceous Nanaimo Group are examined at Hornby and Denman islands, British Columbia, Canada. Evidence for a long-lived submarine conduit records the history of sediment transfer at multiple temporal and spatial scales. The composite submarine channel system deposit is 19.5 km wide and 1500 m thick, which formed and filled over ~ 15 Ma. Facies scale analyses highlight conglomeratic channel fill juxtaposed against thin-bedded out-of-channel deposits. Erosional surfaces are commonly mantled by mass-transport deposits, which provide evidence for conduit wall reworking and maintenance. At a larger scale, a series of composite, conglomerate-prone channelform bodies are observed to stratigraphically stack in two distinct phases: (1) early persistence of laterally offset (migrated) channels; and (2) later vertically aligned and aggraded channels. This stratigraphic trend is comparable to composite, multi-phase degradational-aggradational submarine channel complexes observed globally. As such, we consider

  6. The Stacked Channel-Levee Systems at the Middle Bengal Fan Imaged by High Resolution Seismic Data

    NASA Astrophysics Data System (ADS)

    Schwenk, T.; Spiess, V.; Breitzke, M.; Huebscher, C.

    2001-12-01

    The Bengal Fan is the largest submarine fan on Earth and covers the whole Bay of Bengal. The fan is built up by the sediment load of the Ganges and Brahmaputra rivers, which drain the Himalayan and react to tectonic and climatic changes on land. Therefore the Bengal Fan is well suited to study the linkage between processes on land and the marine sedimentary record. The sediment reaches the deep sea through a canyon deeply incised into the shelf, acting as a temporary trap. Turbidity currents transport the sediment episodically on the fan building successively several channel-levee systems, but only one channel is active at a time. In 1997 during R/V Sonne Cruise SO 125 to the Bay of Bengal, the morphology and structure of the Bengal Fan were studied at different distances from the shelf. In addition, the seismic data were used for an ODP drilling proposal "Drilling in the Bengal Fan" by France-Lanord, Spiess, Molnar & Curray. A main objective of the SO 125 Cruise was the investigation of the middle Bengal Fan at 16.5° N, especially of the architecture of the active channel-levee system. A closely spaced grid of Parasound sediment echosounder, Hydrosweep Swath Sounder and very high-resolution seismic data were collected in the vicinity of the active channel, completed by two long W-E Profiles to the west and the east of the active channel. As seismic sources a watergun with frequencies between 200 and 1600 Hz and a GI Gun with frequencies between 100 and 400 Hz were used in an alternating operation mode. At the middle Bengal Fan, the active channel is characterised by a high sinuosity and an exceptionally low gradient. By a combined Parasound and Hydrosweep survey more than 20 cut-off loops could be identified. The sedimentation on the levees varies strongly and depends on the relative position to the channel loops. The base of the active channel is characterised by high amplitude reflections in the seismic data, which are interpreted as coarse-grained sediments

  7. Constraining the erosional response of deep-water channel systems to growing folds and thrusts, Niger Delta.

    NASA Astrophysics Data System (ADS)

    Whittaker, A. C.; Lonergan, L.; Jolly, B. A.

    2015-12-01

    Gravity-driven folds and thrusts often characterize the slope and deep-water settings of passive margins. These structures exert a significant control on sediment gravity flows because they determine the location and configuration of sediment depo-centres and transport systems. Here we exploit 3D seismic data in the outer toe-thrust region of the deep-water Niger Delta to analyse the interaction between Plio-Pleistocene channel systems and actively-growing folds and thrusts. We first map folds and thrusts from the seismic data and we use this data to reconstruct the history of fold growth in detail. We then make quantitative measurements of the geomorphic response of submarine channels to growing tectonic structures in order to provide new constraints on their long-term erosional dynamics. This information is used to infer morphodyanamic processes that sculpted the channel systems through time, and to estimate the bed shear stresses and fluid velocities of typical flow events. The bathymetric long profiles of these channels have concavities that range from -0.08 to -0.34, and an average gradient of ~1o. Thrusts are associated with a local steepening in channel gradient of up to 3 times, and this effect extends 0.5 - 2 km upstream of the thrust. Within these knickzones, channel incision increases by approximately by a factor of 2, with a corresponding width decrease of approximately 25%. Channel incision across growing structures is achieved through enhanced bed-shear stress driven incision (up to 200 Pa) and flow velocity (up to 5 ms-1) assuming typical bulk sediment concentrations of 0.6%. Comparison of structural uplift since 1.7 Ma, and channel incision over an equivalent period, shows that many of these channels are able to keep pace with the time-integrated uplift since 1.7 Ma, and may have reached a bathymetric steady-state. Generally, bed-shear stresses of ~150 Pa are sufficient to keep pace with structural strain rates of 10-15 s-1. More widely, our data

  8. Design of a 32-Channel EEG System for Brain Control Interface Applications

    PubMed Central

    Wang, Ching-Sung

    2012-01-01

    This study integrates the hardware circuit design and the development support of the software interface to achieve a 32-channel EEG system for BCI applications. Since the EEG signals of human bodies are generally very weak, in addition to preventing noise interference, it also requires avoiding the waveform distortion as well as waveform offset and so on; therefore, the design of a preamplifier with high common-mode rejection ratio and high signal-to-noise ratio is very important. Moreover, the friction between the electrode pads and the skin as well as the design of dual power supply will generate DC bias which affects the measurement signals. For this reason, this study specially designs an improved single-power AC-coupled circuit, which effectively reduces the DC bias and improves the error caused by the effects of part errors. At the same time, the digital way is applied to design the adjustable amplification and filter function, which can design for different EEG frequency bands. For the analog circuit, a frequency band will be taken out through the filtering circuit and then the digital filtering design will be used to adjust the extracted frequency band for the target frequency band, combining with MATLAB to design man-machine interface for displaying brain wave. Finally the measured signals are compared to the traditional 32-channel EEG signals. In addition to meeting the IFCN standards, the system design also conducted measurement verification in the standard EEG isolation room in order to demonstrate the accuracy and reliability of this system design. PMID:22778545

  9. Shannon information capacity of time reversal wideband multiple-input multiple-output system based on correlated statistical channels

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Bing-Zhong, Wang; Shuai, Ding

    2016-05-01

    Utilizing channel reciprocity, time reversal (TR) technique increases the signal-to-noise ratio (SNR) at the receiver with very low transmitter complexity in complex multipath environment. Present research works about TR multiple-input multiple-output (MIMO) communication all focus on the system implementation and network building. The aim of this work is to analyze the influence of antenna coupling on the capacity of wideband TR MIMO system, which is a realistic question in designing a practical communication system. It turns out that antenna coupling stabilizes the capacity in a small variation range with statistical wideband channel response. Meanwhile, antenna coupling only causes a slight detriment to the channel capacity in a wideband TR MIMO system. Comparatively, uncorrelated stochastic channels without coupling exhibit a wider range of random capacity distribution which greatly depends on the statistical channel. The conclusions drawn from information difference entropy theory provide a guideline for designing better high-performance wideband TR MIMO communication systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 61331007, 61361166008, and 61401065) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120185130001).

  10. Design and application of 8-channel SOI-based AWG demultiplexer for CWDM-system

    SciTech Connect

    Juhari, Nurjuliana; Menon, P. Susthitha; Ehsan, Abang Annuar; Shaari, Sahbudin

    2015-04-24

    Arrayed Waveguide Grating (AWG) serving as a demultiplexer (demux) has been designed on SOI platform and was utilized in a Coarse Wavelength Division Multiplexing (CWDM) system ranging from 1471 nm to 1611 nm. The investigation was carried out at device and system levels. At device level, 20 nm (∼ 2500 GHz) channel spacing was successfully simulated using beam propagation method (BPM) under TE mode polarization with a unique double S-shape pattern at arrays region. The performance of optical properties gave the low values of 0.96 dB dB for insertion loss and – 22.38 dB for optical crosstalk. AWG device was then successfully used as demultiplexer in CWDM system when 10 Gb/s data rate was applied in the system. Limitation of signal power due to attenuation and fiber dispersion detected by BER analyzer =10{sup −9} of the system was compared with theoretical value. Hence, the maximum distance of optical fiber can be achieved.

  11. A 160 μW 8-Channel Active Electrode System for EEG Monitoring.

    PubMed

    Jiawei Xu; Yazicioglu, R F; Grundlehner, B; Harpe, P; Makinwa, K A A; Van Hoof, C

    2011-12-01

    This paper presents an active electrode system for gel-free biopotential EEG signal acquisition. The system consists of front-end chopper amplifiers and a back-end common-mode feedback (CMFB) circuit. The front-end AC-coupled chopper amplifier employs input impedance boosting and digitally-assisted offset trimming. The former increases the input impedance of the active electrode to 2 GΩ at 1 Hz and the latter limits the chopping induced output ripple and residual offset to 2 mV and 20 mV, respectively. Thanks to chopper stabilization, the active electrode achieves 0.8 μVrms (0.5-100 Hz) input referred noise. The use of a back-end CMFB circuit further improves the CMRR of the active electrode readout to 82 dB at 50 Hz. Both front-end and back-end circuits are implemented in a 0.18 μm CMOS process and the total current consumption of an 8-channel readout system is 88 μA from 1.8 V supply. EEG measurements using the proposed active electrode system demonstrate its benefits compared to passive electrode systems, namely reduced sensitivity to cable motion artifacts and mains interference. PMID:23852553

  12. A New, Scalable and Low Cost Multi-Channel Monitoring System for Polymer Electrolyte Fuel Cells.

    PubMed

    Calderón, Antonio José; González, Isaías; Calderón, Manuel; Segura, Francisca; Andújar, José Manuel

    2016-01-01

    In this work a new, scalable and low cost multi-channel monitoring system for Polymer Electrolyte Fuel Cells (PEFCs) has been designed, constructed and experimentally validated. This developed monitoring system performs non-intrusive voltage measurement of each individual cell of a PEFC stack and it is scalable, in the sense that it is capable to carry out measurements in stacks from 1 to 120 cells (from watts to kilowatts). The developed system comprises two main subsystems: hardware devoted to data acquisition (DAQ) and software devoted to real-time monitoring. The DAQ subsystem is based on the low-cost open-source platform Arduino and the real-time monitoring subsystem has been developed using the high-level graphical language NI LabVIEW. Such integration can be considered a novelty in scientific literature for PEFC monitoring systems. An original amplifying and multiplexing board has been designed to increase the Arduino input port availability. Data storage and real-time monitoring have been performed with an easy-to-use interface. Graphical and numerical visualization allows a continuous tracking of cell voltage. Scalability, flexibility, easy-to-use, versatility and low cost are the main features of the proposed approach. The system is described and experimental results are presented. These results demonstrate its suitability to monitor the voltage in a PEFC at cell level. PMID:27005630

  13. A New, Scalable and Low Cost Multi-Channel Monitoring System for Polymer Electrolyte Fuel Cells

    PubMed Central

    Calderón, Antonio José; González, Isaías; Calderón, Manuel; Segura, Francisca; Andújar, José Manuel

    2016-01-01

    In this work a new, scalable and low cost multi-channel monitoring system for Polymer Electrolyte Fuel Cells (PEFCs) has been designed, constructed and experimentally validated. This developed monitoring system performs non-intrusive voltage measurement of each individual cell of a PEFC stack and it is scalable, in the sense that it is capable to carry out measurements in stacks from 1 to 120 cells (from watts to kilowatts). The developed system comprises two main subsystems: hardware devoted to data acquisition (DAQ) and software devoted to real-time monitoring. The DAQ subsystem is based on the low-cost open-source platform Arduino and the real-time monitoring subsystem has been developed using the high-level graphical language NI LabVIEW. Such integration can be considered a novelty in scientific literature for PEFC monitoring systems. An original amplifying and multiplexing board has been designed to increase the Arduino input port availability. Data storage and real-time monitoring have been performed with an easy-to-use interface. Graphical and numerical visualization allows a continuous tracking of cell voltage. Scalability, flexibility, easy-to-use, versatility and low cost are the main features of the proposed approach. The system is described and experimental results are presented. These results demonstrate its suitability to monitor the voltage in a PEFC at cell level. PMID:27005630

  14. Metallic contaminant detection system using multi-channel high Tc SQUIDs

    NASA Astrophysics Data System (ADS)

    Tanaka, Saburo; Kitamura, Yoshihiro; Hatsukade, Yoshimi; Ohtani, Takeyoshi; Suzuki, Shuichi

    2012-10-01

    We have developed the magnetic metallic contaminant detectors using multiple high Tc SQUID gradiometers for industrial products. Finding ultra-small metallic contaminants is a big issue for manufacturers producing commercial products. The quality of industrial products such as lithium ion batteries can deteriorate by the inclusion of tiny metallic contaminants. When the contamination does occur, the manufacturer of the product suffers a great loss to recall the tainted products. Metallic particles with outer dimension less than 50 μm cannot be detected by a conventional X-ray imaging. Therefore a high sensitive detection system for small foreign matters is required. However, in most of the cases, the matrix of an active material coated sheet electrode is magnetized and the magnetic signal from the matrix is large enough to mask the signal from contaminants. Thus we have developed a detection system based on a SQUID gradiometer and a horizontal magnetization to date. For practical use, we should increase the detection width of the system by employing multiple sensors. We successfully realized an eight-channel high-Tc SQUID gradiometer system for inspection of sheet electrodes of a lithium ion battery with width of at least 60 to 70 mm. Eight planar SQUID gradiometers were mounted with a separation of 9.0 mm. As a result, small iron particles of less than 50 μm were successfully measured. This result suggests that the system is a promising tool for the detection of contaminants in a lithium ion battery.

  15. Design and application of 8-channel SOI-based AWG demultiplexer for CWDM-system

    NASA Astrophysics Data System (ADS)

    Juhari, Nurjuliana; Menon, P. Susthitha; Ehsan, Abang Annuar; Shaari, Sahbudin

    2015-04-01

    Arrayed Waveguide Grating (AWG) serving as a demultiplexer (demux) has been designed on SOI platform and was utilized in a Coarse Wavelength Division Multiplexing (CWDM) system ranging from 1471 nm to 1611 nm. The investigation was carried out at device and system levels. At device level, 20 nm (˜ 2500 GHz) channel spacing was successfully simulated using beam propagation method (BPM) under TE mode polarization with a unique double S-shape pattern at arrays region. The performance of optical properties gave the low values of 0.96 dB dB for insertion loss and - 22.38 dB for optical crosstalk. AWG device was then successfully used as demultiplexer in CWDM system when 10 Gb/s data rate was applied in the system. Limitation of signal power due to attenuation and fiber dispersion detected by BER analyzer =10-9 of the system was compared with theoretical value. Hence, the maximum distance of optical fiber can be achieved.

  16. Wireless Channel Characterization: Modeling the 5 GHz Microwave Landing System Extension Band for Future Airport Surface Communications

    NASA Technical Reports Server (NTRS)

    Matolak, D. W.; Apaza, Rafael; Foore, Lawrence R.

    2006-01-01

    We describe a recently completed wideband wireless channel characterization project for the 5 GHz Microwave Landing System (MLS) extension band, for airport surface areas. This work included mobile measurements at large and small airports, and fixed point-to-point measurements. Mobile measurements were made via transmission from the air traffic control tower (ATCT), or from an airport field site (AFS), to a receiving ground vehicle on the airport surface. The point-to-point measurements were between ATCT and AFSs. Detailed statistical channel models were developed from all these measurements. Measured quantities include propagation path loss and power delay profiles, from which we obtain delay spreads, frequency domain correlation (coherence bandwidths), fading amplitude statistics, and channel parameter correlations. In this paper we review the project motivation, measurement coordination, and illustrate measurement results. Example channel modeling results for several propagation conditions are also provided, highlighting new findings.

  17. Semi-analytic modeling of FWM noise in dispersion-managed DWDM systems with DQPSK/DPSK/OOK channels

    NASA Astrophysics Data System (ADS)

    Du, Jianxin; Teng, Zhiyu; Shen, Ninghang

    2016-01-01

    Semi-analytic models are developed to deterministically calculate the variances of degenerate and non-degenerate four-wave-mixing (FWM) noises for dispersion-managed dense wavelength division multiplexing (DWDM) systems with pure and mixed differential quadrature-phase-shift keying (DQPSK)/differential phase-shift keying (DPSK)/on-off-keying (OOK) channels. The semi-analytic models include various important propagation effects for exact numerical results. The novel dispersion map used here for dispersion management is composed of effective-area-enlarged positive dispersion fiber (EE-PDF), dispersion slope and dispersion compensating fiber (SCDCF) and nonzero dispersion-shifted fiber (NZ-DSF). It is numerically validated with the new models that, under the condition that all channels have the same average launch powers and baud rates, the impact of FWM noise for mixed DQPSK/OOK channels are more severe than that for pure DQPSK and mixed DQPSK/DPSK channels. It is also shown that the FWM efficiency is strongly dependent on the peak power of launched optical pulse for a large number of channels, as can be mainly attributed to the quasi-linear evolution of pulse shapes in pump channels induced by cross-phase modulation (XPM). Compared with some commercial optical-fiber transmission simulators, massive time-consuming can be avoided by using the newly derived semi-analytic models when transmission performances of such DWDM systems are numerically optimized and evaluated.

  18. Diacetin, a reliable cue and private communication channel in a specialized pollination system

    PubMed Central

    Schäffler, Irmgard; Steiner, Kim E.; Haid, Mark; van Berkel, Sander S.; Gerlach, Günter; Johnson, Steven D.; Wessjohann, Ludger; Dötterl, Stefan

    2015-01-01

    The interaction between floral oil secreting plants and oil-collecting bees is one of the most specialized of all pollination mutualisms. Yet, the specific stimuli used by the bees to locate their host flowers have remained elusive. This study identifies diacetin, a volatile acetylated glycerol, as a floral signal compound shared by unrelated oil plants from around the globe. Electrophysiological measurements of antennae and behavioural assays identified diacetin as the key volatile used by oil-collecting bees to locate their host flowers. Furthermore, electrophysiological measurements indicate that only oil-collecting bees are capable of detecting diacetin. The structural and obvious biosynthetic similarity between diacetin and associated floral oils make it a reliable cue for oil-collecting bees. It is easily perceived by oil bees, but can’t be detected by other potential pollinators. Therefore, diacetin represents the first demonstrated private communication channel in a pollination system. PMID:26245141

  19. An Inflatable and Wearable Wireless System for Making 32-Channel Electroencephalogram Measurements.

    PubMed

    Yu, Yi-Hsin; Lu, Shao-Wei; Chuang, Chun-Hsiang; King, Jung-Tai; Chang, Che-Lun; Chen, Shi-An; Chen, Sheng-Fu; Lin, Chin-Teng

    2016-07-01

    Potable electroencephalography (EEG) devices have become critical for important research. They have various applications, such as in brain-computer interfaces (BCI). Numerous recent investigations have focused on the development of dry sensors, but few concern the simultaneous attachment of high-density dry sensors to different regions of the scalp to receive qualified EEG signals from hairy sites. An inflatable and wearable wireless 32-channel EEG device was designed, prototyped, and experimentally validated for making EEG signal measurements; it incorporates spring-loaded dry sensors and a novel gasbag design to solve the problem of interference by hair. The cap is ventilated and incorporates a circuit board and battery with a high-tolerance wireless (Bluetooth) protocol and low power consumption characteristics. The proposed system provides a 500/250 Hz sampling rate, and 24 bit EEG data to meet the BCI system data requirement. Experimental results prove that the proposed EEG system is effective in measuring audio event-related potential, measuring visual event-related potential, and rapid serial visual presentation. Results of this work demonstrate that the proposed EEG cap system performs well in making EEG measurements and is feasible for practical applications. PMID:26780814

  20. 10-channel fiber array fabrication technique for parallel optical coherence tomography system

    NASA Astrophysics Data System (ADS)

    Arauz, Lina J.; Luo, Yuan; Castillo, Jose E.; Kostuk, Raymond K.; Barton, Jennifer

    2007-02-01

    Optical Coherence Tomography (OCT) shows great promise for low intrusive biomedical imaging applications. A parallel OCT system is a novel technique that replaces mechanical transverse scanning with electronic scanning. This will reduce the time required to acquire image data. In this system an array of small diameter fibers is required to obtain an image in the transverse direction. Each fiber in the array is configured in an interferometer and is used to image one pixel in the transverse direction. In this paper we describe a technique to package 15μm diameter fibers on a siliconsilica substrate to be used in a 2mm endoscopic probe tip. Single mode fibers are etched to reduce the cladding diameter from 125μm to 15μm. Etched fibers are placed into a 4mm by 150μm trench in a silicon-silica substrate and secured with UV glue. Active alignment was used to simplify the lay out of the fibers and minimize unwanted horizontal displacement of the fibers. A 10-channel fiber array was built, tested and later incorporated into a parallel optical coherence system. This paper describes the packaging, testing, and operation of the array in a parallel OCT system.

  1. Performance analysis of 2D asynchronous hard-limiting optical code-division multiple access system through atmospheric scattering channel

    NASA Astrophysics Data System (ADS)

    Zhao, Yaqin; Zhong, Xin; Wu, Di; Zhang, Ye; Ren, Guanghui; Wu, Zhilu

    2013-09-01

    Optical code-division multiple access (OCDMA) systems usually allocate orthogonal or quasi-orthogonal codes to the active users. When transmitting through atmospheric scattering channel, the coding pulses are broadened and the orthogonality of the codes is worsened. In truly asynchronous case, namely both the chips and the bits are asynchronous among each active user, the pulse broadening affects the system performance a lot. In this paper, we evaluate the performance of a 2D asynchronous hard-limiting wireless OCDMA system through atmospheric scattering channel. The probability density function of multiple access interference in truly asynchronous case is given. The bit error rate decreases as the ratio of the chip period to the root mean square delay spread increases and the channel limits the bit rate to different levels when the chip period varies.

  2. Enhanced Handoff Scheme for Downlink-Uplink Asymmetric Channels in Cellular Systems

    PubMed Central

    2013-01-01

    In the latest cellular networks, data services like SNS and UCC can create asymmetric packet generation rates over the downlink and uplink channels. This asymmetry can lead to a downlink-uplink asymmetric channel condition being experienced by cell edge users. This paper proposes a handoff scheme to cope effectively with downlink-uplink asymmetric channels. The proposed handoff scheme exploits the uplink channel quality as well as the downlink channel quality to determine the appropriate timing and direction of handoff. We first introduce downlink and uplink channel models that consider the intercell interference, to verify the downlink-uplink channel asymmetry. Based on these results, we propose an enhanced handoff scheme that exploits both the uplink and downlink channel qualities to reduce the handoff-call dropping probability and the service interruption time. The simulation results show that the proposed handoff scheme reduces the handoff-call dropping probability about 30% and increases the satisfaction of the service interruption time requirement about 7% under high-offered load, compared to conventional mobile-assisted handoff. Especially, the proposed handoff scheme is more efficient when the uplink QoS requirement is much stricter than the downlink QoS requirement or uplink channel quality is worse than downlink channel quality. PMID:24501576

  3. The two-way time synchronization system via a satellite voice channel

    NASA Astrophysics Data System (ADS)

    Heng-Qiu, Zheng; Ren-Huan, Zhang; Yong-Hui, Hu

    1994-05-01

    A newly developed two-way time synchronization system is described in this paper. The system uses one voice channel at a SCPC satellite digital communication earth station, whose bandwidth is only 45 kHz, thus saving satellite resources greatly. The system is composed of one master station and one or several, up to sixty-two, secondary stations. The master and secondary stations are equipped with the same equipment, including a set of timing equipment, a synthetic data terminal for time synchronizing, and a interface unit between the data terminal and the satellite earth station. The synthetic data terminal for time synchronization also has an IRIG-B code generator and a translator. The data terminal of master station is the key part of whole system. The system synchronization process is full automatic, which is controlled by the master station. Employing an autoscanning technique and conversational mode, the system accomplishes the following tasks: linking up liaison with each secondary station in turn, establishing a coarse time synchronization, calibrating date (years, months, days) and time of day (hours, minutes, seconds), precisely measuring the time difference between local station and the opposite station, exchanging measurement data, statistically processing the data, rejecting error terms, printing the data, calculating the clock difference and correcting the phase, thus realizing real-time synchronization from one point to multiple points. We also designed an adaptive phase circuit to eliminate the phase ambiguity of the PSK demodulator. The experiments have shown that the time synchronization accuracy is better than 2 mu S. The system has been put into regular operation.

  4. The two-way time synchronization system via a satellite voice channel

    NASA Technical Reports Server (NTRS)

    Heng-Qiu, Zheng; Ren-Huan, Zhang; Yong-Hui, HU

    1994-01-01

    A newly developed two-way time synchronization system is described in this paper. The system uses one voice channel at a SCPC satellite digital communication earth station, whose bandwidth is only 45 kHz, thus saving satellite resources greatly. The system is composed of one master station and one or several, up to sixty-two, secondary stations. The master and secondary stations are equipped with the same equipment, including a set of timing equipment, a synthetic data terminal for time synchronizing, and a interface unit between the data terminal and the satellite earth station. The synthetic data terminal for time synchronization also has an IRIG-B code generator and a translator. The data terminal of master station is the key part of whole system. The system synchronization process is full automatic, which is controlled by the master station. Employing an autoscanning technique and conversational mode, the system accomplishes the following tasks: linking up liaison with each secondary station in turn, establishing a coarse time synchronization, calibrating date (years, months, days) and time of day (hours, minutes, seconds), precisely measuring the time difference between local station and the opposite station, exchanging measurement data, statistically processing the data, rejecting error terms, printing the data, calculating the clock difference and correcting the phase, thus realizing real-time synchronization from one point to multiple points. We also designed an adaptive phase circuit to eliminate the phase ambiguity of the PSK demodulator. The experiments have shown that the time synchronization accuracy is better than 2 mu S. The system has been put into regular operation.

  5. A dynamic multi-channel speech enhancement system for distributed microphones in a car environment

    NASA Astrophysics Data System (ADS)

    Matheja, Timo; Buck, Markus; Fingscheidt, Tim

    2013-12-01

    Supporting multiple active speakers in automotive hands-free or speech dialog applications is an interesting issue not least due to comfort reasons. Therefore, a multi-channel system for enhancement of speech signals captured by distributed distant microphones in a car environment is presented. Each of the potential speakers in the car has a dedicated directional microphone close to his position that captures the corresponding speech signal. The aim of the resulting overall system is twofold: On the one hand, a combination of an arbitrary pre-defined subset of speakers' signals can be performed, e.g., to create an output signal in a hands-free telephone conference call for a far-end communication partner. On the other hand, annoying cross-talk components from interfering sound sources occurring in multiple different mixed output signals are to be eliminated, motivated by the possibility of other hands-free applications being active in parallel. The system includes several signal processing stages. A dedicated signal processing block for interfering speaker cancellation attenuates the cross-talk components of undesired speech. Further signal enhancement comprises the reduction of residual cross-talk and background noise. Subsequently, a dynamic signal combination stage merges the processed single-microphone signals to obtain appropriate mixed signals at the system output that may be passed to applications such as telephony or a speech dialog system. Based on signal power ratios between the particular microphone signals, an appropriate speaker activity detection and therewith a robust control mechanism of the whole system is presented. The proposed system may be dynamically configured and has been evaluated for a car setup with four speakers sitting in the car cabin disturbed in various noise conditions.

  6. Optimal coding-decoding for systems controlled via a communication channel

    NASA Astrophysics Data System (ADS)

    Yi-wei, Feng; Guo, Ge

    2013-12-01

    In this article, we study the problem of controlling plants over a signal-to-noise ratio (SNR) constrained communication channel. Different from previous research, this article emphasises the importance of the actual channel model and coder/decoder in the study of network performance. Our major objectives include coder/decoder design for an additive white Gaussian noise (AWGN) channel with both standard network configuration and Youla parameter network architecture. We find that the optimal coder and decoder can be realised for different network configuration. The results are useful in determining the minimum channel capacity needed in order to stabilise plants over communication channels. The coder/decoder obtained can be used to analyse the effect of uncertainty on the channel capacity. An illustrative example is provided to show the effectiveness of the results.

  7. Precise SER Analysis and Performance Results of OSTBC MIMO-OFDM Systems over Uncorrelated Nakagami-m Fading Channels

    NASA Astrophysics Data System (ADS)

    Ahmad Ansari, Ejaz; Rajatheva, Nandana

    Although the topic of multiple-input multiple-output (MIMO) based orthogonal frequency division multiplexing (OFDM) over different fading channels is well investigated, its closed form symbol error rate (SER) expressions and performance results employing orthogonal space time block codes (OSTBCs) over uncorrelated frequency-selective Nakagami-m fading channels are still not available. The closed form expressions are extremely useful for evaluating system's performance without carrying out time consuming simulations. Similarly, the performance results are also quite beneficial for determining the system's performance in the sense that many practical wireless standards extensively employ MIMO-OFDM systems in conjunction with M-ary quadrature amplitude modulation (M-QAM) constellation. This paper thus, derives exact closed form expressions for the SER of M-ary Gray-coded one and two dimensional constellations when an OSTBC is employed and Nt transmit antennas are selected for transmission over frequency-selective Nakagami-m fading channels. For this purpose, first an exact closed-form of average SER expression of OSTBC based MIMO-OFDM system for M-ary phase shift keying (M-PSK) using traditional probability density function (PDF) approach is derived. We then compute exact closed form average SER expressions for M-ary pulse amplitude modulation (M-PAM) and M-QAM schemes by utilizing this generalized result. These expressions are valid over both frequency-flat and frequency-selective Nakagami-m fading MIMO channels and can easily be evaluated without using any numerical integration methods. We also show that average SER of MIMO-OFDM system using OSTBC in case of frequency-selective Rayleigh fading channels remains independent to the number of taps, L of that fading channel and the performance of the same system for two-tap un-correlated Rayleigh and Nakagami-m fading channels is better than that of the correlated one. Moreover, Monte Carlo simulation of MIMO-OFDM system

  8. Reducing interferences in wireless communication systems by mobile agents with recurrent neural networks-based adaptive channel equalization

    NASA Astrophysics Data System (ADS)

    Beritelli, Francesco; Capizzi, Giacomo; Lo Sciuto, Grazia; Napoli, Christian; Tramontana, Emiliano; Woźniak, Marcin

    2015-09-01

    Solving channel equalization problem in communication systems is based on adaptive filtering algorithms. Today, Mobile Agents (MAs) with Recurrent Neural Networks (RNNs) can be also adopted for effective interference reduction in modern wireless communication systems (WCSs). In this paper MAs with RNNs are proposed as novel computing algorithms for reducing interferences in WCSs performing an adaptive channel equalization. The method to provide it is so called MAs-RNNs. We perform the implementation of this new paradigm for interferences reduction. Simulations results and evaluations demonstrates the effectiveness of this approach and as better transmission performance in wireless communication network can be achieved by using the MAs-RNNs based adaptive filtering algorithm.

  9. Investigation of the phase fluctuation effect on the BER performance of DPSK space downlink optical communication system on fluctuation channel

    NASA Astrophysics Data System (ADS)

    Li, Mi; Li, Bowen; Zhang, Xuping; Song, Yuejiang; Chang, Lingqian; Chen, Yuan

    2016-05-01

    Phase fluctuation effect is an important phenomenon on bit error rate (BER) performance on fluctuation channel in space downlink optical communication system. During research process, both intensity scintillation and phase fluctuation caused by atmospheric turbulence have been considered on fluctuation channel. Through the analysis of simulation results, the influence of phase fluctuation is not sensitive for wavelength and APD gain factor at high data rate. Besides, receiving diameter and divergence angle can be adjusted properly in order to obtain optimal BER performance. This work is helpful to the research of phase fluctuation and the design of practical system.

  10. Signal acquisition module design for multi-channel surface magnetic resonance sounding system

    NASA Astrophysics Data System (ADS)

    Lin, Tingting; Chen, Wuqiang; Du, Wenyuan; Zhao, Jing

    2015-11-01

    To obtain a precise 2D/3D image of fissure or karst water, multi-channel magnetic resonance sounding (MRS) systems using edge-to-edge or overlapping receiving coils are needed. Thus, acquiring a nano-volt signal for a small amount of the aquifer and suppressing the mutual coupling between adjacent coils are two important issues for the design of the signal acquisition module in the system. In the present study, we propose to use a passive low pass filter, consisted of a resistance (R) and capacitance (C), to inhibit the mutual coupling effects of the coils. Four low-noise operational amplifiers LT1028, OPA124, AD745, and OP27 were compared with respect to achieving the lowest system noise. As a result, 3 pieces of LT1028 were chosen and connected in parallel to serve as preamplifier, with a sensitivity of 1.4 nV/√Hz at 2 kHz. Experimental results are presented for 2D MRS groundwater investigations conducted in the suburb of Changchun, China. The inversion result is consistent with the result of drilling log, suggesting that the signal acquisition module is well developed.

  11. Acid-Sensing Ion Channels as Potential Pharmacological Targets in Peripheral and Central Nervous System Diseases.

    PubMed

    Radu, Beatrice Mihaela; Banciu, Adela; Banciu, Daniel Dumitru; Radu, Mihai

    2016-01-01

    Acid-sensing ion channels (ASICs) are widely expressed in the body and represent good sensors for detecting protons. The pH drop in the nervous system is equivalent to ischemia and acidosis, and ASICs are very good detectors in discriminating slight changes in acidity. ASICs are important pharmacological targets being involved in a variety of pathophysiological processes affecting both the peripheral nervous system (e.g., peripheral pain, diabetic neuropathy) and the central nervous system (e.g., stroke, epilepsy, migraine, anxiety, fear, depression, neurodegenerative diseases, etc.). This review discusses the role played by ASICs in different pathologies and the pharmacological agents acting on ASICs that might represent promising drugs. As the majority of above-mentioned pathologies involve not only neuronal dysfunctions but also microvascular alterations, in the next future, ASICs may be also considered as potential pharmacological targets at the vasculature level. Perspectives and limitations in the use of ASICs antagonists and modulators as pharmaceutical agents are also discussed. PMID:26920689

  12. Signal acquisition module design for multi-channel surface magnetic resonance sounding system.

    PubMed

    Lin, Tingting; Chen, Wuqiang; Du, Wenyuan; Zhao, Jing

    2015-11-01

    To obtain a precise 2D/3D image of fissure or karst water, multi-channel magnetic resonance sounding (MRS) systems using edge-to-edge or overlapping receiving coils are needed. Thus, acquiring a nano-volt signal for a small amount of the aquifer and suppressing the mutual coupling between adjacent coils are two important issues for the design of the signal acquisition module in the system. In the present study, we propose to use a passive low pass filter, consisted of a resistance (R) and capacitance (C), to inhibit the mutual coupling effects of the coils. Four low-noise operational amplifiers LT1028, OPA124, AD745, and OP27 were compared with respect to achieving the lowest system noise. As a result, 3 pieces of LT1028 were chosen and connected in parallel to serve as preamplifier, with a sensitivity of 1.4 nV/√Hz at 2 kHz. Experimental results are presented for 2D MRS groundwater investigations conducted in the suburb of Changchun, China. The inversion result is consistent with the result of drilling log, suggesting that the signal acquisition module is well developed. PMID:26628154

  13. Objective research and application of multi-channel human meridian impedance dynamic testing system

    NASA Astrophysics Data System (ADS)

    Li, Bo; Zhang, Jun; Jiao, Jianling

    2008-10-01

    This paper is an in-depth study on the basis of the passed summary of relevant technologies. Multi-channel ring electrode has been developed to point impedance testing of the human body for the first time. Here, we build such a system, which bases on the hardware platform of AT89C52 combined with M82C54-2, besides, the integrated software development tools micro-soft visual c++ and the technical advantages such as multi-threading, databases, serial communication and the characteristics of real-time supported by Windows XP are used in here too. Except for the point impedance testing of the human body, the conductive volume of the human meridian and infrared-photoelectric absorption properties of physical quantities can also be detected by such an on-site data acquisition, analysis, display, record and communicate with the PC portable System. Currently, the system was being in the testing phase, we have collected some real data of human body with this vehicle, whose results are expected to be more satisfactory in the near future.

  14. In vivo 783-channel diffuse reflectance imaging system and its application

    NASA Astrophysics Data System (ADS)

    Yang, Joon-Mo; Han, Yong-Hui; Yoon, Gilwon; Ahn, Byung Soo; Lee, Byung-Cheon; Soh, Kwang-Sup

    2007-08-01

    A fiber-based reflectance imaging system was constructed to produce in vivo absorption spectroscopic images of biological tissues with diffuse light in the cw domain. The principal part of this system is the 783-channel fiber probe, composed of 253 illumination fibers and 530 detection fibers distributed in a 20×20 mm square region. During illumination with the 253 illumination fibers, diffuse reflected lights are collected by the 530 detection fibers and recorded simultaneously as an image with an electron multiplying CCD camera for fast data acquisition. After signal acquisition, a diffuse reflectance image was reconstructed by applying the spectral normalization method we devised. To test the applicability of the spectral normalization, we conducted two phantom experiments with chicken breast tissue and white Delrin resin by using animal blood as an optical inhomogeneity. In the Delrin phantom experiment, we present images produced by two methods, spectral normalization and reference signal normalization, along with a comparison of the two. To show the feasibility of our system for biomedical applications, we took images of a human vein in vivo with the spectral normalization method.

  15. Alternative splicing contributes to K+ channel diversity in the mammalian central nervous system.

    PubMed Central

    Luneau, C J; Williams, J B; Marshall, J; Levitan, E S; Oliva, C; Smith, J S; Antanavage, J; Folander, K; Stein, R B; Swanson, R

    1991-01-01

    In an attempt to define the molecular basis of the functional diversity of K+ channels, we have isolated overlapping rat brain cDNAs that encoded a neuronal delayed rectifier K+ channel, K,4, that is structurally related to the Drosophila Shaw protein. Unlike previously characterized mammalian K+ channel genes, which each contain a single protein-coding exon, K,4 arises from alternative exon usage at a locus that also encodes another mammalian Shaw homolog, NGK2. Thus, the enormous diversity of K+ channels in mammals can be generated not just through gene duplication and divergence but also through alternative splicing of RNA. Images PMID:2023941

  16. A Low-Complexity Bock Linear Smoothing Channel Estimation for SIMO-OFDM Systems without Cyclic Prefix

    NASA Astrophysics Data System (ADS)

    Yu, Jung-Lang; Chen, Chia-Hao

    Orthogonal frequency-division multiplexing (OFDM) systems often use a cyclic prefix (CP) to simplify the equalization design at the cost of bandwidth efficiency. To increase the bandwidth efficiency, we study the blind equalization with linear smoothing [1] for single-input multiple-output (SIMO) OFDM systems without CP insertion in this paper. Due to the block Toeplitz structure of channel matrix, the block matrix scheme is applied to the linear smoothing channel estimation, which equivalently increases the number of sample vectors and thus reduces the perturbation of sample autocorrelation matrix. Compared with the linear smoothing and subspace methods, the proposed block linear smoothing requires the lowest computational complexity. Computer simulations show that the block linear smoothing yields a channel estimation error smaller than that from linear smoothing, and close to that of the subspace method. Evaluating by the minimum mean-square error (MMSE) equalizer, the block linear smoothing and subspace methods have nearly the same bit-error-rates (BERs).

  17. Compact 32-channel time-resolved single-photon detection system

    NASA Astrophysics Data System (ADS)

    Cuccato, A.; Antonioli, S.; Gulinatti, A.; Labanca, I.; Rech, I.; Ghioni, M.

    2013-05-01

    Nowadays, many research fields like biology, chemistry, medicine and space technology rely on high sensitivity imaging instruments that allow to exploit modern measurement techniques; among these, Time-Correlated Single-Photon Counting (TCSPC) provides extremely high time resolution. Single-photon detectors play a key role in these advanced imaging systems, and in recent years Single-Photon Avalanche Diodes (SPADs) have become a valid alternative to Photo Multiplier Tubes (PMTs). Moreover scientific research has recently focused on single photon detector arrays, pushed by a growing demand for multichannel systems. In this scenario, we developed a compact, stand-alone, 32-channel system for time-resolved single-photon counting applications. The system core is represented by a 32×1 SPAD array built in custom technology, featuring high time resolution, high photon detection efficiency (> 45%) and low dark count rate. The SPAD avalanche signal is exported through an integrated inverter which is placed close to the photo detector, this way the avalanche event is detected with high time resolution while achieving negligible crosstalk between adjacent pixels. SPAD proper operation is guaranteed by a 32×1 mixed passive-active quenching circuit (AQC) array built in 0.18 μm HV-CMOS technology; its digital outputs are fed to an FPGA that performs on-board processing of photon counting information. On the contrary, photon timing information is directly extracted from the pixel array and exported in Current Mode Logic (CML) standard. Preliminary experiments have been carried out on the developed system, resulting in a high time resolution (< 60 ps FWHM) and mean dark count rate lower than 8500 counts/s at 25°C.

  18. Aircraft Engine On-Line Diagnostics Through Dual-Channel Sensor Measurements: Development of an Enhanced System

    NASA Technical Reports Server (NTRS)

    Kobayashi, Takahisa; Simon, Donald L.

    2008-01-01

    In this paper, an enhanced on-line diagnostic system which utilizes dual-channel sensor measurements is developed for the aircraft engine application. The enhanced system is composed of a nonlinear on-board engine model (NOBEM), the hybrid Kalman filter (HKF) algorithm, and fault detection and isolation (FDI) logic. The NOBEM provides the analytical third channel against which the dual-channel measurements are compared. The NOBEM is further utilized as part of the HKF algorithm which estimates measured engine parameters. Engine parameters obtained from the dual-channel measurements, the NOBEM, and the HKF are compared against each other. When the discrepancy among the signals exceeds a tolerance level, the FDI logic determines the cause of discrepancy. Through this approach, the enhanced system achieves the following objectives: 1) anomaly detection, 2) component fault detection, and 3) sensor fault detection and isolation. The performance of the enhanced system is evaluated in a simulation environment using faults in sensors and components, and it is compared to an existing baseline system.

  19. Functional implications of the localization and activity of acid-sensitive channels in rat peripheral nervous system

    PubMed Central

    Alvarez de la Rosa, Diego; Zhang, Ping; Shao, Deren; White, Fletcher; Canessa, Cecilia M.

    2002-01-01

    Acid-sensitive ion channels (ASIC) are proton-gated ion channels expressed in neurons of the mammalian central and peripheral nervous systems. The functional role of these channels is still uncertain, but they have been proposed to constitute mechanoreceptors and/or nociceptors. We have raised specific antibodies for ASIC1, ASIC2, ASIC3, and ASIC4 to examine the distribution of these proteins in neurons from dorsal root ganglia (DRG) and to determine their subcellular localization. Western blot analysis demonstrates that all four ASIC proteins are expressed in DRG and sciatic nerve. Immunohistochemical experiments and functional measurements of unitary currents from the ASICs with the patch–clamp technique indicate that ASIC1 localizes to the plasma membrane of small-, medium-, and large-diameter cells, whereas ASIC2 and ASIC3 are preferentially in medium to large cells. Neurons coexpressing ASIC2 and ASIC3 form predominantly heteromeric ASIC2–3 channels. Two spliced forms, ASIC2a and ASIC2b, colocalize in the same population of DRG neurons. Within cells, the ASICs are present mainly on the plasma membrane of the soma and cellular processes. Functional studies indicate that the pH sensitivity for inactivation of ASIC1 is much higher than the one for activation; hence, increases in proton concentration will inactivate the channel. These functional properties and localization in DRG have profound implications for the putative functional roles of ASICs in the nervous system. PMID:11842212

  20. Functional implications of the localization and activity of acid-sensitive channels in rat peripheral nervous system.

    PubMed

    Alvarez de la Rosa, Diego; Zhang, Ping; Shao, Deren; White, Fletcher; Canessa, Cecilia M

    2002-02-19

    Acid-sensitive ion channels (ASIC) are proton-gated ion channels expressed in neurons of the mammalian central and peripheral nervous systems. The functional role of these channels is still uncertain, but they have been proposed to constitute mechanoreceptors and/or nociceptors. We have raised specific antibodies for ASIC1, ASIC2, ASIC3, and ASIC4 to examine the distribution of these proteins in neurons from dorsal root ganglia (DRG) and to determine their subcellular localization. Western blot analysis demonstrates that all four ASIC proteins are expressed in DRG and sciatic nerve. Immunohistochemical experiments and functional measurements of unitary currents from the ASICs with the patch-clamp technique indicate that ASIC1 localizes to the plasma membrane of small-, medium-, and large-diameter cells, whereas ASIC2 and ASIC3 are preferentially in medium to large cells. Neurons coexpressing ASIC2 and ASIC3 form predominantly heteromeric ASIC2-3 channels. Two spliced forms, ASIC2a and ASIC2b, colocalize in the same population of DRG neurons. Within cells, the ASICs are present mainly on the plasma membrane of the soma and cellular processes. Functional studies indicate that the pH sensitivity for inactivation of ASIC1 is much higher than the one for activation; hence, increases in proton concentration will inactivate the channel. These functional properties and localization in DRG have profound implications for the putative functional roles of ASICs in the nervous system. PMID:11842212

  1. The Nucleolar Channel System of Human Endometrium Is Related to Endoplasmic Reticulum and R-Rings

    PubMed Central

    Kittur, Nupur; Zapantis, Gregory; Aubuchon, Mira; Santoro, Nanette; Bazett-Jones, David P.

    2007-01-01

    The nucleolar channel system (NCS) is a well-established ultrastructural hallmark of the postovulation endometrium. Its transient presence has been associated with human fertility. Nevertheless, the biogenesis, composition, and function of these intranuclear membrane cisternae are unknown. Membrane systems with a striking ultrastructural resemblance to the NCS, termed R-rings, are induced in nuclei of tissue culture cells by overexpression of the central repeat domain of the nucleolar protein Nopp140. Here we provide a first molecular characterization of the NCS and compare the biogenesis of these two enigmatic organelles. Like the R-rings, the NCS consists of endoplasmic reticulum harboring the marker glucose-6-phosphatase. R-ring formation initiates at the nuclear envelope, apparently by a calcium-mediated Nopp140-membrane interaction, as supported by the calcium-binding ability of Nopp140, the inhibition of R-ring formation by calcium chelators, and the concentration of Nopp140 and complexed calcium in R-rings. Although biogenesis of the NCS may initiate similarly, the reduced presence of complexed calcium and Nopp140 suggests the involvement of additional factors. PMID:17429075

  2. Real-time portable dual channel image fusion and data processing system

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Yang, Yong-ying; Wang, Dao-dang; Liu, Dong

    2009-05-01

    Presently electricity utilities make use of a number of inspection tools to survey their transmission lines and electrical distribution equipment. Visible and ultraviolet cameras are the latest visual diagnostic tools available to utilities to identify potential failures on electrical equipment. Based on the DSP and FPGA hardware platform, a system is designed to collect images from both visible and ultraviolet channels. Moreover, it performs image fusion, characteristic enhancement and image analysis as well. For detecting the corona, a ultra-violet quantum detector is used in the form of an image intensifier tube with a Cesium-Telluride photocathode, which is competent for single photon counting. For acquiring visible images, a high-speed industrial CCD is implemented to assure definition of images in terms of 1394 protocol. The real-time images is displayed on a LCD, compressed and saved for further analysis. Finally, several methods of program debugging are introduced. The experimental results in the field show that the designed system has good performance in the detection of corona radiation.

  3. On the performance analysis of SSC diversity system over η-μ fading channels

    NASA Astrophysics Data System (ADS)

    Khatalin, Sari

    2016-06-01

    In this paper, we study key performance measures of dual-branch switch-and-stay combining (SSC) system operating in ? fading environment. Specifically, analytical expressions for the kth order moment, average signal-to-noise ratio, amount of fading and outage probability are obtained for an SSC system operating over ? fading channels. Expressions of the average bit error rate (BER) for coherent detection and non-coherent detection were also derived with SSC for various modulation schemes. The BER expressions for the coherent detection case were derived using the moment generating function-based approach. Some of the final expressions are presented in the form of infinite series. Therefore, those series are truncated and upper bounds are derived for truncation errors. Expressions to determine the optimum adaptive switching thresholds are also presented. Corresponding results for Nakagami-q and Nakagami-m fading are derived in this paper as special cases. Numerical results are provided to demonstrate the applications of the new results.

  4. Test-retest reliability of a single-channel, wireless EEG system.

    PubMed

    Rogers, Jeffrey M; Johnstone, Stuart J; Aminov, Anna; Donnelly, James; Wilson, Peter H

    2016-08-01

    Recording systems to acquire electroencephalogram (EEG) data are traditionally lab-based. However, there are shortcomings to this method, and the ease of use and portability of emerging wireless EEG technologies offer a promising alternative. A previous validity study demonstrated data derived from a single-channel, wireless system (NeuroSky ThinkGear, San Jose, California) is comparable to EEG recorded from conventional lab-based equipment. The current study evaluated the reliability of this portable system using test-retest and reliable change analyses. Relative power (RP) of delta, theta, alpha, and beta frequency bands was derived from EEG data obtained from a single electrode over FP1 in 19 healthy youth (10-17years old), 21 healthy adults (18-28years old), and 19 healthy older adults (55-79years old), during eyes-open, eyes-closed, auditory oddball, and visual n-back conditions. Intra-class correlations (ICCs) and Coefficients of Repeatability (CRs) were calculated from RP data re-collected one-day, one-week, and one-month later. Participants' levels of mood and attention were consistent across sessions. Eyes-closed resting EEG measurements using the portable device were reproducible (ICCs 0.76-0.85) at short and longer retest intervals in all three participant age groups. While still of at least fair reliability (ICCs 0.57-0.85), EEG obtained during eyes-open paradigms was less stable, and any change observed over time during these testing conditions can be interpreted utilizing the CR values provided. Combined with existing validity data, these findings encourage application of the portable EEG system for the study of brain function. PMID:27318008

  5. 32-Channel System to Measure the Electrophysiological Properties of Bioengineered Cardiac Muscle.

    PubMed

    Salazar, Betsy H; Reddy, Anilkumar K; Zewei Tao; Madala, Sridhar; Birla, Ravi K

    2015-06-01

    The purpose of this study was to develop, assess, and validate a custom 32-channel system to analyze the electrical properties of 3-D artificial heart muscle (3D-AHM). In this study, neonatal rat cardiac cells were cultured in a fibrin gel to drive the formation of 3D-AHM. Once the tissues were fully formed, the customized electrocardiogram (EKG) sensing system was used to obtain the different electrophysiological characteristics of the muscle constructs. Additionally, this system was used to evaluate the electrical properties of native rat hearts, for comparison to the fabricated tissues and native values found in the literature. Histological evaluation showed extensive cellularization and cardiac tissue formation. EKG data analysis yielded time delays between the signals ranging from 0 to 7 ms. Optical maps exhibited slight trends in impulse propagation throughout the fabricated tissue. Conduction velocities were calculated longitudinally at 277.81 cm/s, transversely at 300.79 cm/s, and diagonally at 285.68 cm/s for 3D-AHM. The QRS complex exhibited an R-wave amplitude of 438.42 ± 36.96 μV and an average duration of 317.5 ± 16.5 ms for the tissue constructs. The data collected in this study provide a clearer picture about the intrinsic properties of the 3D-AHM while proving our system's efficacy for EKG data procurement. To achieve a viable and permanent solution, the bioengineered heart muscle must physiologically resemble native heart tissue as well as mimic its electrical properties for proper contractile function. This study allows us to monitor such properties and assess the necessary changes that will improve construct development and function. PMID:25667345

  6. Channel-wing System for Thrust Deflection and Force/Moment Generation

    NASA Technical Reports Server (NTRS)

    Englar, Robert J. (Inventor); Bushnell, Dennis M. (Inventor)

    2006-01-01

    An aircraft comprising a Channel Wing having blown c h - ne1 circulation control wings (CCW) for various functions. The blown channel CCW includes a channel that has a rounded or near-round trailing edge. The channel further has a trailing-edge slot that is adjacent to the rounded trailing edge of the channel. The trailing-edge slot has an inlet connected to a source of pressurized air and is capable of tangentially discharging pressurized air over the rounded trailing edge. The aircraft further has a propeller that is located in the channel and ahead of the rounded trailing edge of the channel. The propeller provides a propeller thrust exhaust stream across the channel wing to propel the aircraft through the air and to provide high lift. The pressurized air being discharged over the rounded trailing edge provides a high lift that is obtained independent of an aircraft angle of attack, thus preventing the asymmetry. separated flow, and stall experienced by the CC wing at the high angle of attack it required for high lift generation. The aircraft can further include blown outboard circulation control wings (CCW) that are synergistically connected to the blown channel CCWs. The blown outboard CCWs provide additional high lift, control thrust/drag interchange, and can provide all three aerodynamic moments when differential blowing is applied front-to-rear or left-to-right. Both the blown channel CCW and the outboard CCW also have leading-edge blowing slots to prevent flow separation or to provide aerodynamic moments for control.

  7. 47 CFR 22.725 - Channels for conventional rural radiotelephone stations and basic exchange telephone radio systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Channels for conventional rural radiotelephone stations and basic exchange telephone radio systems. 22.725 Section 22.725 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Rural Radiotelephone Service Conventional Rural...

  8. 47 CFR 22.725 - Channels for conventional rural radiotelephone stations and basic exchange telephone radio systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Channels for conventional rural radiotelephone stations and basic exchange telephone radio systems. 22.725 Section 22.725 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Rural Radiotelephone Service Conventional Rural...

  9. 47 CFR 22.725 - Channels for conventional rural radiotelephone stations and basic exchange telephone radio systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Channels for conventional rural radiotelephone stations and basic exchange telephone radio systems. 22.725 Section 22.725 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Rural Radiotelephone Service Conventional Rural...

  10. 47 CFR 22.725 - Channels for conventional rural radiotelephone stations and basic exchange telephone radio systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Channels for conventional rural radiotelephone stations and basic exchange telephone radio systems. 22.725 Section 22.725 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Rural Radiotelephone Service Conventional Rural...

  11. 47 CFR 22.725 - Channels for conventional rural radiotelephone stations and basic exchange telephone radio systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Channels for conventional rural radiotelephone stations and basic exchange telephone radio systems. 22.725 Section 22.725 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES PUBLIC MOBILE SERVICES Rural Radiotelephone Service Conventional Rural...

  12. 47 CFR 90.625 - Other criteria to be applied in assigning channels for use in conventional systems of communication.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Other criteria to be applied in assigning channels for use in conventional systems of communication. 90.625 Section 90.625 Telecommunication FEDERAL... in the 806-824 Mhz, 851-869 Mhz, 896-901 Mhz, and 935-940 Mhz Bands § 90.625 Other criteria to...

  13. 47 CFR 90.625 - Other criteria to be applied in assigning channels for use in conventional systems of communication.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Other criteria to be applied in assigning channels for use in conventional systems of communication. 90.625 Section 90.625 Telecommunication FEDERAL... in the 806-824 Mhz, 851-869 Mhz, 896-901 Mhz, and 935-940 Mhz Bands § 90.625 Other criteria to...

  14. 47 CFR 90.625 - Other criteria to be applied in assigning channels for use in conventional systems of communication.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Other criteria to be applied in assigning channels for use in conventional systems of communication. 90.625 Section 90.625 Telecommunication FEDERAL... in the 806-824 Mhz, 851-869 Mhz, 896-901 Mhz, and 935-940 Mhz Bands § 90.625 Other criteria to...

  15. 47 CFR 90.625 - Other criteria to be applied in assigning channels for use in conventional systems of communication.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Other criteria to be applied in assigning channels for use in conventional systems of communication. 90.625 Section 90.625 Telecommunication FEDERAL... in the 806-824 Mhz, 851-869 Mhz, 896-901 Mhz, and 935-940 Mhz Bands § 90.625 Other criteria to...

  16. 47 CFR 90.625 - Other criteria to be applied in assigning channels for use in conventional systems of communication.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Other criteria to be applied in assigning channels for use in conventional systems of communication. 90.625 Section 90.625 Telecommunication FEDERAL... in the 806-824 Mhz, 851-869 Mhz, 896-901 Mhz, and 935-940 Mhz Bands § 90.625 Other criteria to...

  17. The Possibility of Increasing the Throughput of a High-Frequency Radio-Communication Channel Using a Mimo System

    NASA Astrophysics Data System (ADS)

    Metelev, S. A.

    2014-09-01

    We consider the possibility of increasing the radio-channel throughput in the high-frequency range by using antenna arrays. The MIMO-system efficiency is studied with the help of the modified Watterson model by the simulation method. The signal parameters for which the MIMO processing yields the best results are determined.

  18. Statistical Characterisation of the Maximum Eigenvalue of a Wishart Distribution with Application to Multi-Channel SAR System

    NASA Astrophysics Data System (ADS)

    Erten, E.; Zandoná-Schneider, R.; Reigber, A.

    2009-04-01

    Multi-channel SAR system characterise the target with multicomponent Gaussian circular vector whose number of components m is equal to the number of polarimetric and/or interferometric channels of the system. In the case of the multivariate (multi-channel) Gaussian system, the second order statistics known as covariance matrix contains all the necessary information to characterise the target vector. In this framework, the eigendecomposition of the covariance matrix have demonstrated as a important analysis in the physical parameter estimation and target detection. Especially, the maximum eigenvalue related to the first eigenvector of the covariance matrix is the most interesting parameter in a wide selection of application, i.e. polarimetry, GMTI (ground moving target indication) and interferometric phase filtering. Related to this, the cornerstone study considering the statistical description of the covariance matrix eigendecomposition in polarimetry has been carried out in [1]. However, the majority of the analysis in [1] was performed on the basis of numerical methods. In this paper we support the results of [1] by addressing analytical solutions. Specifically, we derive new exact closed form expressions for Probability Density Function (PDF), for Cumulative Dis tribution Function (CDF) and for the Moment Generating Function (MGF) of the multi channel SAR system covariance matrix maximum eigenvalue, thus enabling the exact evaluation of the performance analysis of the estimation and the detection problem considering the number of averaged samples and different correlation scenario. Our results are analysed by means of simulated data.

  19. Co-evolution of Riparian Vegetation and Channel Dynamics in an Aggrading Braided River System, Mount Pinatubo, Philippines

    NASA Astrophysics Data System (ADS)

    Gran, K. B.; Michal, T.

    2014-12-01

    Increased bank stability by riparian vegetation in braided rivers can decrease bed reworking rates and focus the flow. The magnitude of influence and resulting channel morphology are functions of vegetation strength vs. channel dynamics, a concept encapsulated in a dimensionless ratio between timescales for vegetation growth and channel reworking known as T*. We investigate this relationship in an aggrading braided river at Mount Pinatubo, Philippines, and compare results to numerical and physical models. Gradual reductions in post-eruption sediment loads have reduced bed reworking rates, allowing vegetation to persist year-round and impact channel dynamics on the Pasig-Potrero and Sacobia Rivers. From 2009-2011, we collected data detailing vegetation extent, type, density, and root strength. Incorporating these data into RipRoot and BSTEM models shows cohesion due to roots increased from zero in unvegetated conditions to >10.2 kPa in densely-growing grasses. Field-based parameters were incorporated into a cellular model comparing vegetation growth and sediment mobility effects on braided channel dynamics. The model shows that both low sediment mobility and high vegetation strength lead to less active systems, reflecting trends observed in the field. An estimated T* between 0.8 - 2.3 for the Pasig-Potrero River suggests channels were mobile enough to maintain the braidplain width clear of vegetation and even experience slight gains in area through annual removal of existing vegetation. However, persistent vegetation focused flow and thus aggradation over the unvegetated fraction of braidplain, leading to an aggradational imbalance and transition to a more avulsive state. While physical models predict continued narrowing of the active braidplain as T* declines, the future trajectory of channel-vegetation interactions at Pinatubo as sedimentation rates decline appears more complicated due to strong seasonal variability in precipitation and sediment loads. By 2011

  20. Electro-optical channel drop switching in a photonic crystal waveguide-cavity side-coupling system

    NASA Astrophysics Data System (ADS)

    Chang, Kao-Der; Liu, Cheng-Yang

    2014-04-01

    The electro-optical channel drop switching in a photonic crystal waveguide-cavity side-coupling system is reported. The line waveguide is formed by removing a single row of dielectric cylinders. The twin optical microcavities side coupled between linear waveguides is studied by solving Maxwell's equations. We determine the general characteristics of the coupling element required to achieve channel drop tunneling. By modulating the conductance of the twin microcavities, the electrical tunability of the resonant modes is observed in the transmission spectrum. The spectral characteristics suggest a potential application for this switching device as an efficient multichannel optical switch in the photonic integrated circuits.

  1. Estimation of Symmetric Channels for Discrete Cosine Transform Type-I Multicarrier Systems: A Compressed Sensing Approach

    PubMed Central

    Domínguez-Jiménez, María Elena; Luengo, David; Sansigre-Vidal, Gabriela

    2015-01-01

    The problem of channel estimation for multicarrier communications is addressed. We focus on systems employing the Discrete Cosine Transform Type-I (DCT1) even at both the transmitter and the receiver, presenting an algorithm which achieves an accurate estimation of symmetric channel filters using only a small number of training symbols. The solution is obtained by using either matrix inversion or compressed sensing algorithms. We provide the theoretical results which guarantee the validity of the proposed technique for the DCT1. Numerical simulations illustrate the good behaviour of the proposed algorithm. PMID:26568981

  2. Vertical profiles of atmospheric fluorescent aerosols observed by a mutil-channel lidar spectrometer system

    NASA Astrophysics Data System (ADS)

    Huang, Z.; Huang, J.; Zhou, T.; Sugimoto, N.; Bi, J.

    2015-12-01

    Zhongwei Huang1*, Jianping Huang1, Tian Zhou1, Nobuo Sugimoto2, Jianrong Bi1 and Jinsen Shi11Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China. 2Atmospheric Environment Division, National Institutes for Environmental Studies, Tsukuba, Japan Email: huangzhongwei@lzu.edu.cn Abstract Atmospheric aerosols have a significant impact on regional and globe climate. The challenge in quantifying aerosol direct radiative forcing and aerosol-cloud interactions arises from large spatial and temporal heterogeneity of aerosol concentrations, compositions, sizes, shape and optical properties (IPCC, 2007). Lidar offers some remarkable advantages for determining the vertical structure of atmospheric aerosols and their related optical properties. To investigate the characterization of atmospheric aerosols (especially bioaerosols) with high spatial and temporal resolution, we developed a Raman/fluorescence/polarization lidar system employed a multi-channel spectrometer, with capabilities of providing measurements of Raman scattering and laser-induced fluorescence excitation at 355 nm from atmospheric aerosols. Meanwhile, the lidar system operated polarization measurements both at 355nm and 532nm wavelengths, aiming to obtain more information of aerosols. It employs a high power pulsed laser and a received telescope with 350mm diameter. The receiver could simultaneously detect a wide fluorescent spectrum about 178 nm with spectral resolution 5.7 nm, mainly including an F/3.7 Crossed Czerny-Turner spectrograph, a grating (1200 gr/mm) and a PMT array with 32 photocathode elements. Vertical structure of fluorescent aerosols in the atmosphere was observed by the developed lidar system at four sites across northwest China, during 2014 spring field observation that conducted by Lanzhou University. It has been proved that the developed lidar could detect the fluorescent aerosols with high temporal and

  3. Before-after environmental impact assessment of an artificial channel opening on a south-western Atlantic choked lagoon system.

    PubMed

    Prestrelo, L; Monteiro-Neto, C

    2016-07-01

    This study aimed to evaluate the human induced impact of a channel opening in a choked lagoon and attempted to establish the cause-effect links for the observed changes. The same lagoon system was sampled before and after the channel opening event, and the differences in fish and crustacean assemblages and environmental variables between these periods analysed. The opening of the artificial channel resulted in salinity increases, leading to a shift in species composition, favouring marine species and reducing abundance and diversity of previously dominant freshwater species. Furthermore, saltwater entrance into the choked lagoon caused an unexpected decrease in species richness and biomass, plus deterioration of ecosystem processes, reducing fishing capacity. The effects of salinity on the ecosystem vary depending on the ecosystem's composition and capacity to overcome salinity changes, thus specific monitoring projects are important strategies for developing coastal lagoon conservation management. PMID:27250914

  4. Microfluidic channel fabrication method

    DOEpatents

    Arnold, Don W.; Schoeniger, Joseph S.; Cardinale, Gregory F.

    2001-01-01

    A new channel structure for microfluidic systems and process for fabricating this structure. In contrast to the conventional practice of fabricating fluid channels as trenches or grooves in a substrate, fluid channels are fabricated as thin walled raised structures on a substrate. Microfluidic devices produced in accordance with the invention are a hybrid assembly generally consisting of three layers: 1) a substrate that can or cannot be an electrical insulator; 2) a middle layer, that is an electrically conducting material and preferably silicon, forms the channel walls whose height defines the channel height, joined to and extending from the substrate; and 3) a top layer, joined to the top of the channels, that forms a cover for the channels. The channels can be defined by photolithographic techniques and are produced by etching away the material around the channel walls.

  5. Characteristics and roles of the volume-sensitive outwardly rectifying (VSOR) anion channel in the central nervous system.

    PubMed

    Akita, T; Okada, Y

    2014-09-01

    Cell volume regulation (CVR) is essential for all types of cells in the central nervous system (CNS) to counteract cell volume changes that may be associated with neuronal activities or diseases and with osmosensing in the hypothalamus, to facilitate morphological changes during cell proliferation, differentiation and migration, and to execute apoptosis of cells. The regulation is attained by regulating the net influx or efflux of solutes and water across the plasma membrane. The volume-sensitive outwardly rectifying (VSOR) anion channel plays a major role in providing a pathway for anion flux during the regulation. The VSOR anion channel is permeable not only to Cl(-) ions but also to amino acids like glutamate and taurine. This property confers a means of intercellular communications through the opening of the channel in the CNS. Thus exploring the roles of VSOR anion channels is crucial to understand the basic principles of cellular functions in the CNS. Here we review biophysical and pharmacological characteristics of the VSOR anion channel in the CNS, discuss its activation mechanisms and roles in the CNS reported so far, and give some perspectives on the next issues to be examined in the near future. PMID:24937753

  6. SINCGARS (Single-Channel Ground/Airborne Radio System) operator performance decay

    NASA Astrophysics Data System (ADS)

    Palmer, Richard L.; Buckalew, Louis W.

    1988-11-01

    The Single-Channel Ground/Airborne Radio System (SINCGARS) is scheduled to replace the Army's VRC-12 and PRC-77 radios. However, SINCGARS is more complex to operate and requires more training. This study examined the decay of operational skills and knowledge in two groups of recently trained operators who went without exposure to SINCGARS for several weeks. Performance levels were measured with the SINCGARS Learning-Retention Test (SLRT), a simulated hands-on performance test emphasizing skills and operational knowledge retention. The results provided tentative indications that operators may lose about 10 percent of their prior performance levels within the first few weeks. This figure is expected to vary considerably, depending on the type of soldier, the length of the nonexposure period, and other conditions. It was also found that performance level was correlated with soldiers' Armed Services Vocational Aptitude Battery (ASVAB) General Technical (GT) scores. Correlations between GT and SLRT scores obtained at two different times were .43 and .50, respectively. However, no relation was observed between performance decay and GT. Further evaluation of operator performance decay needs to be done to determine the effect of longer periods of nonexposure (e.g., 60 and 90 days).

  7. Assessing the feasibility of detecting a hemorrhagic type stroke using a 16 channel magnetic induction system

    NASA Astrophysics Data System (ADS)

    Dekdouk, B.; Ktistis, C.; Armitage, D. W.; Peyton, A. J.

    2010-04-01

    Magnetic induction tomography (MIT) has been proposed as a possible method for imaging stroke in the human brain. Hemorrhagic stroke is characterized by local blood accumulation in the brain and exhibits a greater change in conductivity with frequency compared to other tissues which is observed in the frequency range of interest [1-10] MHz. In this study, we investigate the feasibility of detecting hemorrhagic stroke using absolute and frequency difference imaging. For this purpose, a model of the head originally obtained from MRI and X-ray data was used, to which a large stroke (50 ml) was added. In addition, a model of a 16 channel circular array MIT system was employed. The received coil induced voltages were computed using a custom eddy current solver, based on the finite difference method. For absolute imaging, the induced voltages at the receiver coils were calculated from various coil combinations at 10 MHz frequency together with anticipated systematic errors and biases (orientation and displacement of the coils, movement of the head). The induced voltage noise due to these systematic inaccuracies was compared with the voltage change due to the stroke. In order to decrease the impact of this noise, frequency difference was also considered, whereby measurements were performed at another frequency (1MHz) and subtracted. Comparison results are presented and a realistic picture is delivered with to regard the required mechanical stability and electronics accuracy for this particular medical application

  8. Communication and Control System for a 15-Channel Hermetic Retinal Prosthesis

    PubMed Central

    Kelly, Shawn K.; Shire, Douglas B.; Chen, Jinghua; Doyle, Patrick; Gingerich, Marcus D.; Cogan, Stuart F.; Drohan, William A.; Theogarajan, Luke S.; Wyatt, John L.; Rizzo, Joseph F.

    2011-01-01

    A small, hermetic, wirelessy-controlled retinal prosthesis has been developed for pre-clinical studies in Yucatan minipigs. The device was attached conformally to the outside of the eye in the socket and received both power and data wirelessly from external sources. Based on the received image data, the prosthesis drove a subretinal thin-film polyimide array of sputtered iridium oxide stimulating electrodes. The implanted device included a hermetic titanium case containing a 15-channel stimulator and receiver chip and discrete circuit components. Feedthroughs in the hermetic case connected the chip to secondary power- and data-receiving coils, which coupled to corresponding external power and data coils driven by power amplifiers. Power was delivered by a 125 KHz carrier, and data were delivered by amplitude shift keying of a 15.5 MHz carrier at 100 Kbps. Stimulation pulse strength, duration and frequency were programmed wirelessly from an external computer system. The final assembly was tested in vitro in physiological saline and in vivo in two minipigs for up to five and a half months by measuring stimulus artifacts generated by the implant’s current drivers. PMID:21927618

  9. Fetal cardiac activity analysis during twin pregnancy using a multi-channel SQUID system

    NASA Astrophysics Data System (ADS)

    Costa Monteiro, E.; Schleussner, E.; Kausch, S.; Grimm, B.; Schneider, A.; Hall Barbosa, C.; Haueisen, J.

    2001-05-01

    The use of SQUID magnetometers for non-invasive in utero assessment of cardiac electrical disturbances has already been shown to be a valuable clinical tool. In this way, its applicability also for the complicated case of twin pregnancy, in which the proximity of the cardiac magnetic source of each fetus can hamper the individual analysis of cardiac electrical activity, is of clinical interest. In this paper, we present fetal magnetocardiography performed on a mother pregnant of twins with 26 weeks gestational age, measured inside a magnetically shielded room, by using two identical 31-channel low- Tc SQUID magnetometer systems. Each sensor array has been positioned over one of the fetuses, according to its heart position previously assessed with the aid of ultrasound measurements. The raw data is initially averaged in time and, afterwards, analyzed by means of time plots and isofield maps. The time recordings allow the study of the morphology of each fetus’ cardiac signal and the cardiac time intervals. The resultant equivalent dipole obtained from the isofield maps indicates the position and orientation of each fetus heart. The results agree with the ultrasound analysis performed immediately before the measurements and used to obtain the approximate location of the fetuses’ hearts. Since a distinct analysis of the cardiac electrical activity of each fetus could be achieved, the results indicate the potential of the fetal magnetocardiography in the individual antenatal diagnosis of each one of the fetuses of a twin pregnancy.

  10. Evaluation of a limestone channel and wetland system for treating acid mine drainage

    SciTech Connect

    Brenner, F.J.; Pruent, P.

    1999-07-01

    The Carpentertown Coal and Coke Company operated two drift mines on the site for 17 years closing in December 1987, but the company continued to operate a cleaning plant and coal refuse disposal site until the company declared bankruptcy in June 1989. In summer of 1993, eight acid seeps developed from the 2 ha coal refuse site with a combined flow of 36 1/min with iron and manganese loading rates of 419 and 576 gm/day. In 1995, a 212 m (700 ft) open limestone channel (OLC) and a 344 m{sup 2} (1,142 ft{sup 2}) and a 2,110 m{sup 2}(43,750 ft{sup 2}) aerobic wetland was constructed as a passive treatment system. over the 34-month monitoring period, the acid loading to the receiving stream was reduced by 88% with a corresponding increase of 111% in alkalinity. The iron and manganese loading to the receiving stream was reduced by 91% and 57%, respectively.

  11. Channel based generating function approach to the stochastic Hodgkin-Huxley neuronal system.

    PubMed

    Ling, Anqi; Huang, Yandong; Shuai, Jianwei; Lan, Yueheng

    2016-01-01

    Internal and external fluctuations, such as channel noise and synaptic noise, contribute to the generation of spontaneous action potentials in neurons. Many different Langevin approaches have been proposed to speed up the computation but with waning accuracy especially at small channel numbers. We apply a generating function approach to the master equation for the ion channel dynamics and further propose two accelerating algorithms, with an accuracy close to the Gillespie algorithm but with much higher efficiency, opening the door for expedited simulation of noisy action potential propagating along axons or other types of noisy signal transduction. PMID:26940002

  12. Channel based generating function approach to the stochastic Hodgkin-Huxley neuronal system

    PubMed Central

    Ling, Anqi; Huang, Yandong; Shuai, Jianwei; Lan, Yueheng

    2016-01-01

    Internal and external fluctuations, such as channel noise and synaptic noise, contribute to the generation of spontaneous action potentials in neurons. Many different Langevin approaches have been proposed to speed up the computation but with waning accuracy especially at small channel numbers. We apply a generating function approach to the master equation for the ion channel dynamics and further propose two accelerating algorithms, with an accuracy close to the Gillespie algorithm but with much higher efficiency, opening the door for expedited simulation of noisy action potential propagating along axons or other types of noisy signal transduction. PMID:26940002

  13. Channel based generating function approach to the stochastic Hodgkin-Huxley neuronal system

    NASA Astrophysics Data System (ADS)

    Ling, Anqi; Huang, Yandong; Shuai, Jianwei; Lan, Yueheng

    2016-03-01

    Internal and external fluctuations, such as channel noise and synaptic noise, contribute to the generation of spontaneous action potentials in neurons. Many different Langevin approaches have been proposed to speed up the computation but with waning accuracy especially at small channel numbers. We apply a generating function approach to the master equation for the ion channel dynamics and further propose two accelerating algorithms, with an accuracy close to the Gillespie algorithm but with much higher efficiency, opening the door for expedited simulation of noisy action potential propagating along axons or other types of noisy signal transduction.

  14. Cut-off rate calculations for the outer channel in a concatenated cooling system

    NASA Technical Reports Server (NTRS)

    Herro, M. A.; Costello, D. J., Jr.; Hu, L.

    1984-01-01

    Concatenated codes were long used as a practical means of achieving long block or constraint lengths for combating errors on very noisy channels. The inner and outer encoders are normally separated by an interleaver, so that decoded error bursts coming from the inner decoder are randomized before entering the outer decoder. The effectiveness of this interleaver is examined by calculating the cut-off rate of the outer channel seen by the outer decoder with and without interleaving. Interleaving never hurts the performance of a concatenated code, and when the inner code rate is near the cut-off rate of the inner channel, interleaving significantly improves code performance.

  15. Exploring the Membrane Potential of Simple Dual-Membrane Systems as Models for Gap-Junction Channels.

    PubMed

    Escalona, Yerko; Garate, Jose A; Araya-Secchi, Raul; Huynh, Tien; Zhou, Ruhong; Perez-Acle, Tomas

    2016-06-21

    The conductance of ion channels can be modulated by a transmembrane potential difference, due to alterations on ion-mobility and also by changes in the pore structure. Despite the vast knowledge regarding the influence of voltage on transport properties of ion channels, little attention has been paid to describe, with atomic detail, the modulation of ionic transport in gap-junction channels (GJCs). Hence, molecular dynamics simulations were performed to explore the conductance of simple dual-membrane systems that account for the very basic features of GJCs. In doing so, we studied the influence of different charge distributions in the channel surface on these idealized systems under external electric fields, paying attention to the behavior of the electrostatic potential, ion density, ion currents, and equilibrium properties. Our results demonstrate that the incorporation of a charge distribution akin GJCs decreased anionic currents, favoring the transport of cationic species. Moreover, a thermodynamic characterization of ionic transport in these systems demonstrate the existence of a kinetic barrier that hinders anionic currents, reinforcing the role played by the internal arrangement of charges in GJCs. Overall, our results provide insights at the atomic scale on the effects of charge distributions over ionic transport, constituting a step forward into a better understanding of GJCs. PMID:27332126

  16. A New High Channel-Count, High Scan-Rate, Data Acquisition System for the NASA Langley Transonic Dynamics Tunnel

    NASA Technical Reports Server (NTRS)

    Ivanco, Thomas G.; Sekula, Martin K.; Piatak, David J.; Simmons, Scott A.; Babel, Walter C.; Collins, Jesse G.; Ramey, James M.; Heald, Dean M.

    2016-01-01

    A data acquisition system upgrade project, known as AB-DAS, is underway at the NASA Langley Transonic Dynamics Tunnel. AB-DAS will soon serve as the primary data system and will substantially increase the scan-rate capabilities and analog channel count while maintaining other unique aeroelastic and dynamic test capabilities required of the facility. AB-DAS is configurable, adaptable, and enables buffet and aeroacoustic tests by synchronously scanning all analog channels and recording the high scan-rate time history values for each data quantity. AB-DAS is currently available for use as a stand-alone data system with limited capabilities while development continues. This paper describes AB-DAS, the design methodology, and the current features and capabilities. It also outlines the future work and projected capabilities following completion of the data system upgrade project.

  17. The effects of receiver tracking phase error on the performance of the concatenated Reed-Solomon/Viterbi channel coding system

    NASA Technical Reports Server (NTRS)

    Liu, K. Y.

    1981-01-01

    Analytical and experimental results are presented of the effects of receiver tracking phase error, caused by weak signal conditions on either the uplink or the downlink or both, on the performance of the concatenated Reed-Solomon (RS) Viterbi channel coding system. The test results were obtained under an emulated S band uplink and X band downlink, two way space communication channel in the telecommunication development laboratory of JPL with data rates ranging from 4 kHz to 20 kHz. It is shown that, with ideal interleaving, the concatenated RS/Viterbi coding system is capable of yielding large coding gains at very low bit error probabilities over the Viterbi decoded convolutional only coding system. Results on the effects of receiver tracking phase errors on the performance of the concatenated coding system with antenna array combining are included.

  18. Phase locking of a seven-channel continuous wave fibre laser system by a stochastic parallel gradient algorithm

    SciTech Connect

    Volkov, M V; Garanin, S G; Dolgopolov, Yu V; Kopalkin, A V; Kulikov, S M; Sinyavin, D N; Starikov, F A; Sukharev, S A; Tyutin, S V; Khokhlov, S V; Chaparin, D A

    2014-11-30

    A seven-channel fibre laser system operated by the master oscillator – multichannel power amplifier scheme is the phase locked using a stochastic parallel gradient algorithm. The phase modulators on lithium niobate crystals are controlled by a multichannel electronic unit with the microcontroller processing signals in real time. The dynamic phase locking of the laser system with the bandwidth of 14 kHz is demonstrated, the time of phasing is 3 – 4 ms. (fibre and integrated-optical structures)

  19. Geomorphic (de-) coupling of hillslope and channel systems within headwater catchments in two subarctic tributary valleys, Nordfjord, Western Norway

    NASA Astrophysics Data System (ADS)

    Laute, Katja; Beylich, Achim A.

    2010-05-01

    Hillslopes occupy large areas of the earth surface. Studying the characteristics, development and interaction of hillslopes as components of the geomorphic hillslope-channel coupling process-response system will improve the understanding of the complex response of mountain landscape formation. The rates of hillslope processes are exceptionally varied and affected by many influences of varying intensity. Hillslope-channel coupling and sediment storage within slopes are important factors that influence sediment delivery through catchments, especially in steep environments. Within sediment transfers from sources to sinks in drainage basins, hillslopes function as a key element concerning sediment storage, both for short term periods as between rainstorms as well as for longer periods in colluvial deposits. This PhD project is part of the NFR funded SedyMONT-Norway project within the ESF TOPO-EUROPE SedyMONT (Timescales of sediment dynamics, climate and topographic change in mountain landscapes) programme. The focus of this study is on geomorphic hillslope-channel coupling or de-coupling and sediment transport within four distinct headwater areas of the Erdalen and Bødalen catchments in the Nordfjord valley-fjord system (inner Nordfjord, Western Norway). Both catchments can be described as steep, U-shaped and glacier-fed, subarctic tributary valleys. Approximately 14% of the 49 km2 large headwater area of Erdalen is occupied by hillslope deposits; in Bødalen hillslope deposits occupy 12% of the 42 km2 large headwater area. The main aims of the study are to present preliminary findings on (i) the identification of possible sediment sources and delivery pathways within the headwater areas of the catchments, (ii) to analyze the development of hillslope-channel coupling / de-coupling from postglacial to contemporary timescales as well as (iii) to investigate the current degree of geomorphic hillslope-channel coupling within the different headwater catchments and (iv) to

  20. Development of nine-channel 10-micrometer (Hg, Cd)Te pushbroom IR/CCD system

    NASA Technical Reports Server (NTRS)

    White, W. J.; Wasa, S.

    1977-01-01

    The engineering development of the 9-channel detector array is documented. The development of the array demonstrates the feasibility of a self scanned multi-element infrared detector focal plane. Procedures for operating the array are outlined.

  1. Ca2+ Permeable AMPA Channels in Diseases of the Nervous System

    PubMed Central

    Weiss, John H.

    2011-01-01

    Since the discovery and molecular characterization of Ca2+-permeable AMPA channels just over two decades ago, a large body of evidence has accumulated implicating contributions of these unusual glutamate activated channels to selective neurodegeneration in certain conditions, including ischemia and amyotrophic lateral sclerosis. Factors likely involved in their contributions to disease include their distinct patterns of expression in certain neuronal populations, their upregulation via various mechanisms in response to disease associated stresses, and their high permeability to Zn2+ as well as to Ca2+. However, full characterization of their contributions to certain diseases as well as development of therapeutics has been limited by the lack of selective and bioavailable blockers of these channels that can be employed in animals or humans. This review summarizes some of the clues that have emerged over recent years to the contributions of these channels in disease. PMID:22102834

  2. Development of a 150 000 channel MSGC tracking system for the experiment HERA-B

    NASA Astrophysics Data System (ADS)

    Zeuner, T.

    1997-02-01

    The universities of Heidelberg, Siegen and Zürich are preparing the inner tracker of the HERA-B experiment at DESY designed to measure CP violation in B meson decays. The system consists of 200 MSGC chambers of sizes up to 30 × 30 cm 2 with a total of 150 000 electronic channels. Rates up to 10 4 s -1 mm -2 have to be handled. The gold electrodes (300 μm pitch) are produced by a lift-off process on an alkali-free glass (300 μm thick). The glass is CVD coated with amorphous carbon with a surface resistivity of 10 14ω/□. It provides the required lifetime of 5 years with an integrated charge of 30 mC per cm of the anode length. Gains > 5000 are obtained. The efficiency is greater than 99% with negligible noise rate. Measures to avoid deterioration of the anodes by discharges caused by heavy ionizing particles are discussed. The MSGC detectors are connected to hybrid electronics via Kapton foils. A special bonding machine has been built which allows the adjustment by a video system and the chariots moved by micrometer screws and contains electronically steered glue dispenser and pressure pistons. Members of the collaboration are: T. Beckmann, C. Bresch, H.-B. Dreis, F. Eisele, S. Feuerstack, S. Hausmann, A. Hölscher, T. Hott, A. Lange, A. Maag, V. Myalitsin, P. Robmann, B. Schmidt, S. Schmidt, S. Steiner, U. Straumann, P. Truöl, S. Visbeck, A.-H. Walenta, T. Walter, U. Werthenbach, G. Zech and T. Zeuner.

  3. Multi-channel Data Acquisition System for a 500 m DC HTS Power Cable in Ishikari

    NASA Astrophysics Data System (ADS)

    Ivanov, Yury V.; Chikumoto, Noriko; Watanabe, Hirofumi; Takano, Hirohisa; Inoue, Noriyuki; Yamaguchi, Satarou

    Reduction of heat penetrating into the cryogenic region is the important method of optimization of superconducting devices. In the cases of short-range power transmission lines and compact HTS devices like magnets, the heat leakage through current leads is relatively large. In order to decrease this contribution, current leads equipped with Peltier elements can be used. The mentioned technology is being actively developed in the Chubu University. Commercial samples of Peltier current leads are installed at the terminals of 500-meter DC HTS cable in Ishikari (Hokkaido). This cable is designed for 5 kA. The inner conducting layer consists of 37 DI-BSCCO HTS tapes from Sumitomo Electric Industries, Ltd. with a critical current of 180 A; and the outer one consists of 35 tapes of the same type. Each end of the cable's tape is connected to the individual Peltier current lead. Accordingly, each of the two terminals is equipped with 72 Peltier current leads, 144 pieces in total. In order to examine behavior of the current leads in detail, each piece is supplied with two thermocouples; there are also voltage taps on feedthrough and on HTS tape end. In addition, current through Peltier current lead can be measured by means of individual current transformer. The hardware part of the data acquisition system includes four Keithley 3706A multimeters equipped with 60-channel model 3724 FET multiplexer cards. Therefore, 144 data blocks are formed. Furthermore, there are 72 measurements of a voltage drop across HTS tape. Sampling period is set to be 3 s. The program part of the data acquisition system was written using LabVIEW software solution (National Instruments Corp.).

  4. Photoacoustic imaging of brachytherapy seeds using a channel-domain ultrasound array system

    NASA Astrophysics Data System (ADS)

    Harrison, Tyler; Zemp, Roger J.

    2011-03-01

    Brachytherapy is a technique commonly used in the treatment of prostate cancer that relies on the precise placement of small radioactive seeds near the tumor location. The advantage of this technique over traditional radiation therapies is that treatment can be continuous and uniform, resulting in fewer clinic visits and a shorter treatment duration. Two important phases of this treatment are needle guidance for implantation, and post-placement verification for dosimetry. Ultrasound is a common imaging modality used for these purposes, but it can be difficult to distinguish the seeds from surrounding tissues, often requiring other imaging techniques such as MRI or CT. Photoacoustic imaging may offer a viable alternative. Using a photoacoustic system based on an L7- 4 array transducer and a realtime ultrasound array system capable of parallel channel data acquisition streamed to a multi-core computer via PCI-express, we have demonstrated imaging of these seeds at an ultrasound depth of 16 mm and laser penetration depths ranging up to 50 mm in chicken tissue with multiple optical wavelengths. Ultrasound and photoacoustic images are coregistered via an interlaced pulse sequence. Two laser pulses are used to form a photoacoustic image, and at these depths, the brachytherapy seeds are detected with a signal-to-noise ratio of over 26dB. To obtain this result, 1064nm light was used with a fluence of 100mJ/cm2, the ANSI limit for human skin exposure at this wavelength. This study demonstrates the potential for photoacoustic imaging as a candidate technology for brachytherapy seed placement guidance and verification.

  5. Gramicidin Channels: Versatile Tools

    NASA Astrophysics Data System (ADS)

    Andersen, Olaf S.; Koeppe, Roger E., II; Roux, Benoît

    Gramicidin channels are miniproteins in which two tryptophan-rich subunits associate by means of transbilayer dimerization to form the conducting channels. That is, in contrast to other ion channels, gramicidin channels do not open and close; they appear and disappear. Each subunit in the bilayer-spanning channel is tied to the bilayer/solution interface through hydrogen bonds that involve the indole NH groups as donors andwater or the phospholipid backbone as acceptors. The channel's permeability characteristics are well-defined: gramicidin channels are selective for monovalent cations, with no measurable permeability to anions or polyvalent cations; ions and water move through a pore whose wall is formed by the peptide backbone; and the single-channel conductance and cation selectivity vary when the amino acid sequence is varied, even though the permeating ions make no contact with the amino acid side chains. Given the plethora of available experimental information—for not only the wild-type channels but also for channels formed by amino acid-substituted gramicidin analogues—gramicidin channels continue to provide important insights into the microphysics of ion permeation through bilayer-spanning channels. For similar reasons, gramicidin channels constitute a system of choice for evaluating computational strategies for obtaining mechanistic insights into ion permeation through the more complex channels formed by integral membrane proteins.

  6. Fading channel simulator

    SciTech Connect

    Argo, P.E.; Fitzgerald, T.J.

    1991-12-31

    This invention relates to high frequency (HF) radio signal propagation through fading channels and, more particularly, to simulation of fading channels in order to characterize HF radio system performance in transmitting and receiving signals through such fading channels. Fading channel effects on a transmitted communication signal are simulated with both frequency and time variations using a channel scattering function to affect the transmitted signal. A conventional channel scattering function is converted to a series of channel realizations by multiplying the square root of the channel scattering function by a complex number of which the real and imaginary parts are each independent variables. The two-dimensional inverse-FFT of this complex-valued channel realization yields a matrix of channel coefficients that provide a complete frequency-time description of the channel. The transmitted radio signal is segmented to provide a series of transmitted signal and each segment is subject to FFT to generate a series of signal coefficient matrices. The channel coefficient matrices and signal coefficient matrices are then multiplied and subjected to inverse-FFT to output a signal representing the received affected radio signal. A variety of channel scattering functions can be used to characterize the response of a transmitter-receiver system to such atmospheric effects.

  7. Evaluation of the SHOALS 1000T Bathymetric LIDAR System for Monitoring Channel Sediment Within the Colorado River in Arizona

    NASA Astrophysics Data System (ADS)

    Davis, P. A.; Gonzales, F. M.; Brown, K. M.; Melis, T. S.

    2005-12-01

    The Grand Canyon Monitoring and Research Center of the U.S. Geological Survey monitors sediment transport and storage within the Colorado River ecosystem in Arizona in order to develop flow protocols for the Glen Canyon dam that preserve or restore aquatic and terrestrial habitats. Currently, monitoring the channel sediments is accomplished using acoustic multi-beam surveys, which are very time-consuming. We explored more efficient collection systems that could provide a 2-m point spacing and a vertical accuracy of 25 cm or better. The dual-beam SHOALS 1000T LIDAR system, which simultaneously collects bathymetric and topographic data, could meet these requirements if flown at a 300 m altitude. This low altitude required this fixed-wing system to be modified for helicopter collection to navigate the sinuous, steep-walled canyon. We tested the helicopter-based SHOALS on two segments of the Colorado River - the San Juan River confluence at Lake Powell and the southern portion of Glen Canyon near Lees Ferry. The test flights occurred in late November after a high-flow dam experiment. Early winter storms injected such large volumes of sediment into the unmanaged San Juan River that the SHOALS green laser could not penetrate the water's surface. The water at Lees Ferry was relatively clear (Secchi depths of 7-7.5 m) because there are no tributaries between Lees Ferry and Glen Canyon dam and because the dam maintained a low steady flow for a week following the high-flow experiment in order for ground and aerial surveys to collect monitoring data. At a 300 m altitude, the SHOALS scanner produced a 60-m ground swath. Seven separate flight lines were collected - more than necessary to cover the 100-m-wide channel. Three GPS stations were operated within 30 km of the test flights. Within the areas of overlap between each pair of the seven SHOALS flight lines we found the reproducibility of the SHOALS data to be 19 cm in the channel and 21 cm on land. At Lees Ferry, 20 land

  8. Orbital angular momentum in four channel spatial domain multiplexing system for multi-terabit per second communication architectures

    NASA Astrophysics Data System (ADS)

    Murshid, Syed H.; Muralikrishnan, Hari P.; Kozaitis, Samuel P.

    2012-06-01

    Bandwidth increase has always been an important area of research in communications. A novel multiplexing technique known as Spatial Domain Multiplexing (SDM) has been developed at the Optronics Laboratory of Florida Institute of Technology to increase the bandwidth to T-bits/s range. In this technique, space inside the fiber is used effectively to transmit up to four channels of same wavelength at the same time. Experimental and theoretical analysis shows that these channels follow independent helical paths inside the fiber without interfering with each other. Multiple pigtail laser sources of exactly the same wavelength are used to launch light into a single carrier fiber in a fashion that resulting channels follow independent helical trajectories. These helically propagating light beams form optical vortices inside the fiber and carry their own Orbital Angular Momentum (OAM). The outputs of these beams appear as concentric donut shaped rings when projected on a screen. This endeavor presents the experimental outputs and simulated results for a four channel spatially multiplexed system effectively increasing the system bandwidth by a factor of four.

  9. Outage capacity and outage rate performance of MIMO free-space optical system over strong turbulence channel

    NASA Astrophysics Data System (ADS)

    Hasan, Omar M.; Taha, Mohamed; Abu Sharkh, Osama

    2016-06-01

    In this paper, we investigate outage capacity, outage probability, and outage rate performance of multiple-input multiple-output (MIMO) free-space optical system operating over strong turbulence channels. The MIMO optical system employs intensity modulation direct detection with on-off signaling, and equal gain combining technique at the receiver. We derived novel closed-form expressions for three system metrics, namely, outage capacity, outage probability, and outage rate. Expressions derived here are based on the generalized Gamma-Gamma channel model, which is based on scintillation theory that assumes that the irradiance of the received optical wave is modeled as the product of small-scale and large-scale turbulence eddies. The results are evaluated for different values of received signal-to-noise ratios, strong turbulence conditions, and several values of transmit/receive diversity.

  10. Sequence stratigraphic model and Evolution of the Channelized depositional systems during Miocene in Ulleung Basin southeastern margin, East Sea

    NASA Astrophysics Data System (ADS)

    Baek, Y.; Lee, S. H.; Kim, H. J.; Jou, H. T.

    2015-12-01

    The southwestern margin of Ulleung Basin consists of broad and gentle slope continental shelf and shelf break. The sedimentary succession of the continental shelf is divided into nine sequences (S1-S9). The sedimentary succession is consists of the lower pro-graded sequences (from S2 to S6; 16.5-8.2 Ma) and upper channelized depositional sequences (S7 and S8; 8.2-5.5 Ma) in the Miocene. It progressively thickens northeast ward, suggesting a significant contribution of sediments into the basin margin. The channelized depositional system of S7 is divided into two subunits in which lower boundaries of each subunit are indicated by erosional truncation and channel incision. The underlying subunit 1 has two main streams; the progressive directions are to the NNE (a) and ENE (b). The main stream of subunit 2, developed after giving rise to the low-relief topography of the subunit 1, is only overlapping main stream (a) of subunit 1. The gentle sloped proximal-middle zone has different internal reflector, subunit 1 is characterized by parallel to chaotic reflections, whereas the subunit 2 is dominated by continuous and inclined reflectors, which can be interpreted that sediments supply is increase in subunit 2 than subunit 1. The steep sloped distal zone of channelized depositional systems connected the shelf break. The slope gradient is more slanted subunit 2 than 1. The internal structures are dis-continuous and inclined chaotic internal reflectors, which is interpreted mass transport deposits (MTDs). The slope failures commonly start near the shelf break, but some others are connected perpendicular to the main stream. The upper boundary of subunit 2 is truncated by transgressive surface. The stacking pattern of sequence 7 suggests the type-1 sequence controlled by sea level change, and the internal erosional surface in the channelized depositional systems can be interpreted that formed by tectonic or relative sea level flocculation during late Miocene in East Sea.

  11. Development of a 512-Channel Module for Digital X-Ray Imaging Systems with Silicon Strip Detectors

    SciTech Connect

    Bolanos, L.; Cabal, A. E.; Grybos, P.; Maj, P.; Swientek, K.; Szczygiel, R.; Marzari, A.; Prino, F.; Ramello, L.

    2008-08-11

    We present the development of a 512-channel module for high counting rate digital X-ray imaging systems. The module consists of 512 silicon micro-strips equipped with 8 64-channel readout ASICs called DEDIX. The detectors of 300 {mu}m thickness have strips with 100 micron pitch and strip length of 1 or 2 cm. Detectors were designed with the possibility of choosing the cutting edge distance from the active area in the range from 60 {mu}m down to 20 {mu}m. To obtain good detection efficiency at the relevant energies (10-50 keV) the module works in edge-on configuration: strips are oriented parallel to the incoming X-ray beam. The DEDIX ASIC has a binary readout architecture. Each channel is built of a charge sensitive amplifier (CSA) with pole-zero cancellation circuit, a shaper, two independent discriminators and two independent 20-bit counters. Internal correction DAC implemented in each channel independently ensures a low spread of discriminator effective threshold. This module has been characterized for noise and matching performance having in mind possible future applications like dual energy mammography and angiography. An equivalent noise charge is below 210 el rms for a 1 cm long strip detector and below 250 el. rms for 2 cm long strip detector with 100 {mu}m pitch. The spread of discriminator effective threshold for 512 channels is 16 el. rms, while the high counting rate performance has been demonstrated by the measurement up to 1 MHz average rate of input signals per single channel.

  12. Designing a Low-noise, High-resolution, and Portable Four Channel Acquisition System for Recording Surface Electromyographic Signal

    PubMed Central

    Pashaei, Akbar; Yazdchi, Mohammad Reza; Marateb, Hamid Reza

    2015-01-01

    In current years, the application of biopotential signals has received a lot of attention in literature. One of these signals is an electromyogram (EMG) generated by active muscles. Surface EMG (sEMG) signal is recorded over the skin, as the representative of the muscle activity. Since its amplitude can be as low as 50 μV, it is sensitive to undesirable noise signals such as power-line interferences. This study aims at designing a battery-powered portable four-channel sEMG signal acquisition system. The performance of the proposed system was assessed in terms of the input voltage and current noise, noise distribution, synchronization and input noise level among different channels. The results indicated that the designed system had several inbuilt operational merits such as low referred to input noise (lower than 0.56 μV between 8 Hz and 1000 Hz), considerable elimination of power-line interference and satisfactory recorded signal quality in terms of signal-to-noise ratio. The muscle conduction velocity was also estimated using the proposed system on the brachial biceps muscle during isometric contraction. The estimated values were in then normal ranges. In addition, the system included a modular configuration to increase the number of recording channels up to 96. PMID:26951952

  13. Expression of a Diverse Array of Ca2+-Activated K+ Channels (SK1/3, IK1, BK) that Functionally Couple to the Mechanosensitive TRPV4 Channel in the Collecting Duct System of Kidney.

    PubMed

    Li, Yue; Hu, Hongxiang; Butterworth, Michael B; Tian, Jin-Bin; Zhu, Michael X; O'Neil, Roger G

    2016-01-01

    The voltage- and Ca2+-activated, large conductance K+ channel (BK, maxi-K) is expressed in the collecting duct system of kidney where it underlies flow- and Ca2+-dependent K+ excretion. To determine if other Ca2+-activated K+ channels (KCa) may participate in this process, mouse kidney and the K+-secreting mouse cortical collecting duct (CCD) cell line, mCCDcl1, were assessed for TRPV4 and KCa channel expression and cross-talk. qPCR mRNA analysis and immunocytochemical staining demonstrated TRPV4 and KCa expression in mCCDcl1 cells and kidney connecting tubule (CNT) and CCD. Three subfamilies of KCa channels were revealed: the high Ca2+-binding affinity small-conductance SK channels, SK1and SK3, the intermediate conductance channel, IK1, and the low Ca2+-binding affinity, BK channel (BKα subunit). Apparent expression levels varied in CNT/CCD where analysis of CCD principal cells (PC) and intercalated cells (IC) demonstrated differential staining: SK1:PCIC, IK1:PC>IC, BKα:PC = IC, and TRPV4:PC>IC. Patch clamp analysis and fluorescence Ca2+ imaging of mCCDcl1 cells demonstrated potent TRPV4-mediated Ca2+ entry and strong functional cross-talk between TRPV4 and KCa channels. TRPV4-mediated Ca2+ influx activated each KCa channel, as evidenced by selective inhibition of KCa channels, with each active KCa channel enhancing Ca2+ entry (due to membrane hyperpolarization). Transepithelial electrical resistance (TEER) analysis of confluent mCCDcl1 cells grown on permeable supports further demonstrated this cross-talk where TRPV4 activation induce a decrease in TEER which was partially restored upon selective inhibition of each KCa channel. It is concluded that SK1/SK3 and IK1 are highly expressed along with BKα in CNT and CCD and are closely coupled to TRPV4 activation as observed in mCCDcl1 cells. The data support a model in CNT/CCD segments where strong cross talk between TRPV4-mediated Ca2+ influx and each KCa channel leads to enhance Ca2+ entry which

  14. Expression of a Diverse Array of Ca2+-Activated K+ Channels (SK1/3, IK1, BK) that Functionally Couple to the Mechanosensitive TRPV4 Channel in the Collecting Duct System of Kidney

    PubMed Central

    Li, Yue; Hu, Hongxiang; Butterworth, Michael B.; Tian, Jin-Bin; Zhu, Michael X.; O’Neil, Roger G.

    2016-01-01

    The voltage- and Ca2+-activated, large conductance K+ channel (BK, maxi-K) is expressed in the collecting duct system of kidney where it underlies flow- and Ca2+-dependent K+ excretion. To determine if other Ca2+-activated K+ channels (KCa) may participate in this process, mouse kidney and the K+-secreting mouse cortical collecting duct (CCD) cell line, mCCDcl1, were assessed for TRPV4 and KCa channel expression and cross-talk. qPCR mRNA analysis and immunocytochemical staining demonstrated TRPV4 and KCa expression in mCCDcl1 cells and kidney connecting tubule (CNT) and CCD. Three subfamilies of KCa channels were revealed: the high Ca2+-binding affinity small-conductance SK channels, SK1and SK3, the intermediate conductance channel, IK1, and the low Ca2+-binding affinity, BK channel (BKα subunit). Apparent expression levels varied in CNT/CCD where analysis of CCD principal cells (PC) and intercalated cells (IC) demonstrated differential staining: SK1:PCIC, IK1:PC>IC, BKα:PC = IC, and TRPV4:PC>IC. Patch clamp analysis and fluorescence Ca2+ imaging of mCCDcl1 cells demonstrated potent TRPV4-mediated Ca2+ entry and strong functional cross-talk between TRPV4 and KCa channels. TRPV4-mediated Ca2+ influx activated each KCa channel, as evidenced by selective inhibition of KCa channels, with each active KCa channel enhancing Ca2+ entry (due to membrane hyperpolarization). Transepithelial electrical resistance (TEER) analysis of confluent mCCDcl1 cells grown on permeable supports further demonstrated this cross-talk where TRPV4 activation induce a decrease in TEER which was partially restored upon selective inhibition of each KCa channel. It is concluded that SK1/SK3 and IK1 are highly expressed along with BKα in CNT and CCD and are closely coupled to TRPV4 activation as observed in mCCDcl1 cells. The data support a model in CNT/CCD segments where strong cross talk between TRPV4-mediated Ca2+ influx and each KCa channel leads to enhance Ca2+ entry which

  15. Hydromorphological parameters of natural channel behavior in conditions of the Hercynian System and the flysch belt of the Western Carpathians on the territory of the Czech Republic

    NASA Astrophysics Data System (ADS)

    Kujanová, Kateřina; Matoušková, Milada; Kliment, Zdeněk

    2016-04-01

    A fundamental prerequisite for assessing the current ecological status of streams is the establishment of reference conditions for each stream type that serve as a benchmark. The hydromorphological reference conditions reflect the natural channel behavior, which is extremely variable. Significant parameters of natural channel behavior were determined using a combination of four selected statistical methods: Principal Component Analysis, Agglomerative Hierarchical Clustering, correlation, and regression. Macroscale analyses of data about altitude, stream order, channel slope, valley floor slope, sinuosity, and characteristics of the hydrological regime were conducted for 3197 reaches of major rivers in the Czech Republic with total length of 15,636 km. On the basis of selected significant parameters and their threshold values, channels were classified into groups of river characteristics based on shared behaviors. The channel behavior within these groups was validated using hydromorphological characteristics of natural channels determined during field research at reference sites. Classification of channels into groups confirmed the fundamental differences between channel behavior under conditions of the Hercynian System and the flysch belt of the Western Carpathians in the Czech Republic and determined a specific group in the flattened high areas of mountains in the Bohemian Massif. Validating confirmed the distinctions between groups of river characteristics and the uniqueness of each one; it also emphasized the benefits of using qualitative data and riparian zone characteristics for describing channel behavior. Channel slope, entrenchment ratio, bed structure, and d50 were determined as quantitative characteristics of natural channel behavior.

  16. Numerical modeling and simulation of hot air jet anti-icing system employing channels for enhanced heat transfer

    NASA Astrophysics Data System (ADS)

    Ahmed, Kamran Zaki

    Aircraft icing is a serious concern for the aviation community since it is one of the major causes of fatal aircraft accidents. Aircrafts use different anti-icing systems and one such system is the hot-air anti-icing system, which utilizes hot-air from the engine compressor bleed to heat critical aircraft surfaces and prevent ice formation. Numerous experimental and numerical studies have been performed to increase the efficiency of the hot-air jet based anti-icing systems. Most of the investigations have focused on either orifice design or the impingement region of target surface geometry. Since the impingement surface heat transfer drops off sharply past the stagnation region, investigators have studied the use of multiple jets to enhance surface heat transfer over a larger area. However, use of multiple jets is a further strain on engine resources. One way to conserve engine resources is to use single jet in conjunction with various geometric and physical mechanisms to enhance heat transfer. The current study focuses on enhancing heat transfer using a single jet and a channel. The study investigates the effect of channel's height, inlet location and Reynolds number on heat transfer characteristics in terms of average Nusselt number distribution along the impingement surface. The commercial CFD code, FLUENT, is used to simulate the different cases. Results indicate that the heat transfer depends strongly on height and width of channel, jet-to-target spacing, inlet angle and jet Reynolds number.

  17. Dominant geomorphic controls on channel capacity and flood risk in a hydrologically variable fluvial system

    NASA Astrophysics Data System (ADS)

    Daley, James; Croke, Jacky; Thompson, Chris; Cohen, Tim

    2016-04-01

    Traditionally, particular emphasis has been placed on the hydrological characteristics of rivers to understand the role of channel morphology in flood risk. However, in regions of high hydrological variability, the relationship between channel characteristics and flood conveyance is often highly complex. Consequently in these settings, the applicability of stream discharge or steady-state form-process relationships, may be of less use to understanding flood conveyance. In the subtropical region of southeast Queensland, Australia, rivers are characterized by highly variable flows and entrenched channel morphologies. The latter are such dramatic features, they are termed 'macrochannels'. Following the extreme flood of 2011 in the Lockyer Creek in this region, longitudinal variations in the macrochannel form were found to be a significant factor in flood conveyance. Nine reaches were identified on a basis of flood inundation extent, with significant non-linear changes in channel capacity and discharge, alternating between flood expansion and contraction zones with associated increases and decreases in flood risk. Detailed geomorphic and chronostratigraphic analyses presented here indicate that macrochannel capacity is being strongly influenced by the antecedent bedrock topography, resistant valley-fill and abrupt downstream changes in sediment delivery. A large proportion of the valley fill represents a major Late Pleistocene aggradation phase of fine-grained alluvium that overlies older Pleistocene basal sediments. Subsequent channel incision at 10 ka reoccupied a pre-existing bedrock valley and resistant Pleistocene alluvium imposed substantial controls on the capacity for lateral adjustment. Abrupt changes in sediment supply associated with the location of tributaries provide further evidence for geomorphic controls on macrochannel form and capacity. Identification of the dominant geomorphic factors influencing the overall macrochannel form highlights the relative

  18. Strong nonlinear saturation absorption-induced optical pinhole channel and super-resolution effects: a multi-layer system model.

    PubMed

    Wei, Jingsong; Yan, Hui

    2014-11-15

    This work focuses on the strong nonlinear saturation absorption (NSA)-induced optical super-resolution effect. A multi-layer system model is proposed to understand the strong NSA-induced formation of an optical pinhole channel and the generation of a super-resolution spot. Taking a Sb2Te3 thin film as an example, numerical simulations were conducted. The results illustrate that an optical pinhole channel is clearly formed by the NSA characteristics. This pinhole channel is similar to a near-field light probe. Light travels through the pinhole channel, and a super-resolution spot is generated at its apex. The near-field spot scanning experimental results show that the reduction ratio of the spot is approximately 44.8%, which is basically consistent with the numerical simulation result of 43%. This work is helpful for understanding optical nonlinear super-resolution effects and developing nanolithography, nanodata storage, high-resolution optical imaging technologies with nonlinear thin films. PMID:25490475

  19. Cooperative Reformable Channel System with Unique Recognition of Small Gas Molecules in a two-dimensional ZIF-membrane

    NASA Astrophysics Data System (ADS)

    Motevalli, Benyamin; Taherifar, Neda; Liu, Zhe

    We report a cooperative reformable channel system in a coordination porous polymer, named as ZIF-L. Three types of local flexible ligands coexist in the crystal structure of this polymer, resulting in ultra-flexibility. The reformable channel is able to regulate permeation of a nonspherical guest molecule, such as N2 or CO2, based on its longer molecular dimension, which is in a striking contrast to conventional molecular sieves that regulate the shorter cross-sectional dimension of the guest molecules. Our density functional theory (DFT) calculations reveal that the guest molecule induces dynamic motion of the flexible ligands, leading to the channel reformation, and then the guest molecule reorientates itself to fit in the reformed channel. Such a unique ``induced fit-in'' mechanism causes the gas molecule to pass through 6 membered-ring windows in the c- crystal direction of ZIF-L with its longer axis parallel to the window plane. Our experimental permeance of N2 through the ZIF-L membranes is about three times greater than that of CO2, supporting the DFT simulation predictions.

  20. Using the plant vacuole as a biological system to investigate the functional properties of exogenous channels and transporters.

    PubMed

    Festa, M; Lagostena, L; Carpaneto, A

    2016-03-01

    Plant cells possess a large intracellular compartment that animal cells do not, the central vacuole, which has been investigated for a long time. The central vacuole can occupy up to 90% of the cellular volume and, differently from intracellular organelles from animal cells such as lysosomes or endosomes, it is easy to isolate. Because of its large dimension (up to 40μm diameter) it can be successfully studied using the classical patch-clamp technique. Following the idea that the vacuolar membrane could be used as a convenient model to characterize the functional properties of channel-forming peptides, we verified that the phytotoxic lipodepsipeptide Syringopeptin 25A from Pseudomonas syringae pv syringae was able to form ionic pores in sugar beet vacuoles and we performed a detailed biophysical analysis. Recently, we extended the use of plant vacuoles to the expression and functional characterization of animal intracellular transporters, namely rat CLC-7, and channels, i.e. human TPC2. Since endo-lysosomal transporters and channels are still largely unexplored, principally because their intracellular localization renders them difficult to study, we believe that this novel approach will prove to be a powerful system for the investigation of the molecular mechanisms of exogenous transporters and channels. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale. PMID:26431786

  1. Calcium channel ligand binding to intact, concanavalin A and cyclic AMP-treated cells of the immune system.

    PubMed

    Pinchuk, G V; Pinchuk, L N; Tkachenko, Y V; Rudenko, A E

    1990-12-01

    To examine whether the cells of immune system express calcium channel-forming proteins, we studied the binding of calcium channel ligands, known to detect certain types of the above channels in excitable tissues, to murine splenic and human peripheral blood mononuclear cells. Specific (i.e., displaceable by excess cold ligand) binding of the 3H-labelled dihydropyridine drugs PN200-110 and nitrendipine, was not detected in these cells. Specific binding of a phenylalkylamine drug, [3H]verapamil, was detected, but cannot be attributed to the existence of certain specialized receptors, since multiple [3H]verapamil binding sites (about 10(6) per cell) appeared to be occupied. [3H]Verapamil binding to murine splenic mononuclear cells was inhibited following exposure to either the polyclonal T-cell activator, concanavalin A, or a cell-permeable analogue of the second messenger, cyclic AMP, suggesting that processes of lymphocyte activation and/or intracellular signalling may down-modulate at least some of calcium channel ligand binding sites. PMID:1964929

  2. Involvement of ATP-sensitive potassium channels and the opioid system in the anticonvulsive effect of zolpidem in mice.

    PubMed

    Sheikhi, Mehdi; Shirzadian, Armin; Dehdashtian, Amir; Amiri, Shayan; Ostadhadi, Sattar; Ghasemi, Mehdi; Dehpour, Ahmad Reza

    2016-09-01

    Zolpidem is a hypnotic medication that mainly exerts its function through activating γ-aminobutyric acid (GABA)A receptors. There is some evidence that zolpidem may have anticonvulsive effects. However, the mechanisms underlying this effect have not been elucidated yet. In the present study, we used the pentylentetrazole (PTZ)-induced generalized seizure model in mice to investigate whether zolpidem can affect seizure threshold. We also further evaluated the roles of ATP-sensitive potassium (KATP) channels as well as μ-opioid receptors in the effects of zolpidem on seizure threshold. Our data showed that zolpidem in a dose-dependent manner increased the PTZ-induced seizure threshold. The noneffective (i.e., did not significantly alter the PTZ-induced seizure threshold by itself) doses of KATP channel blocker (glibenclamide) and nonselective opioid receptor antagonist (naloxone) were able to inhibit the anticonvulsive effect of zolpidem. Additionally, noneffective doses of either KATP channel opener (cromakalim) or nonselective μ-opioid receptor agonist (morphine) in combination with a noneffective dose of zolpidem exerted a significant anticonvulsive effect on PTZ-induced seizures in mice. A combination of noneffective doses of naloxone and glibenclamide, which separately did not affect zolpidem effect on seizure threshold, inhibited the anticonvulsive effects of zolpidem. These results suggest a role for KATP channels and the opioid system, alone or in combination, in the anticonvulsive effects of zolpidem. PMID:27521722

  3. Bit Error Rate Analysis for MC-CDMA Systems in Nakagami-[InlineEquation not available: see fulltext.] Fading Channels

    NASA Astrophysics Data System (ADS)

    Li, Zexian; Latva-aho, Matti

    2004-12-01

    Multicarrier code division multiple access (MC-CDMA) is a promising technique that combines orthogonal frequency division multiplexing (OFDM) with CDMA. In this paper, based on an alternative expression for the[InlineEquation not available: see fulltext.]-function, characteristic function and Gaussian approximation, we present a new practical technique for determining the bit error rate (BER) of multiuser MC-CDMA systems in frequency-selective Nakagami-[InlineEquation not available: see fulltext.] fading channels. The results are applicable to systems employing coherent demodulation with maximal ratio combining (MRC) or equal gain combining (EGC). The analysis assumes that different subcarriers experience independent fading channels, which are not necessarily identically distributed. The final average BER is expressed in the form of a single finite range integral and an integrand composed of tabulated functions which can be easily computed numerically. The accuracy of the proposed approach is demonstrated with computer simulations.

  4. New approach to information fusion for Lipschitz classifiers ensembles: Application in multi-channel C-OTDR-monitoring systems

    NASA Astrophysics Data System (ADS)

    Timofeev, Andrey V.; Egorov, Dmitry V.

    2016-06-01

    This paper presents new results concerning selection of an optimal information fusion formula for an ensemble of Lipschitz classifiers. The goal of information fusion is to create an integral classificatory which could provide better generalization ability of the ensemble while achieving a practically acceptable level of effectiveness. The problem of information fusion is very relevant for data processing in multi-channel C-OTDR-monitoring systems. In this case we have to effectively classify targeted events which appear in the vicinity of the monitored object. Solution of this problem is based on usage of an ensemble of Lipschitz classifiers each of which corresponds to a respective channel. We suggest a brand new method for information fusion in case of ensemble of Lipschitz classifiers. This method is called "The Weighing of Inversely as Lipschitz Constants" (WILC). Results of WILC-method practical usage in multichannel C-OTDR monitoring systems are presented.

  5. Implementation of a real-time multi-channel gateway server in ubiquitous integrated biotelemetry system for emergency care (UIBSEC).

    PubMed

    Cheon, Gyeongwoo; Shin, Il Hyung; Jung, Min Yang; Kim, Hee Chan

    2009-01-01

    We developed a gateway server to support various types of bio-signal monitoring devices for ubiquitous emergency healthcare in a reliable, effective, and scalable way. The server provides multiple channels supporting real-time N-to-N client connections. We applied our system to four types of health monitoring devices including a 12-channel electrocardiograph (ECG), oxygen saturation (SpO(2)), and medical imaging devices (a ultrasonograph and a digital skin microscope). Different types of telecommunication networks were tested: WIBRO, CDMA, wireless LAN, and wired internet. We measured the performance of our system in terms of the transmission rate and the number of simultaneous connections. The results show that the proposed network communication strategy can be successfully applied to the ubiquitous emergency healthcare service by providing a fast rate enough for real-time video transmission and multiple connections among patients and medical personnel. PMID:19964662

  6. Communication systems, transceivers, and methods for generating data based on channel characteristics

    DOEpatents

    Forman, Michael A; Young, Derek

    2012-09-18

    Examples of methods for generating data based on a communications channel are described. In one such example, a processing unit may generate a first vector representation based in part on at least two characteristics of a communications channel. A constellation having at least two dimensions may be addressed with the first vector representation to identify a first symbol associated with the first vector representation. The constellation represents a plurality of regions, each region associated with a respective symbol. The symbol may be used to generate data, which may stored in an electronic storage medium and used as a cryptographic key or a spreading code or hopping sequence in a modulation technique.

  7. Organization of the channel-switching process in parallel computer systems based on a matrix optical switch

    NASA Technical Reports Server (NTRS)

    Golomidov, Y. V.; Li, S. K.; Popov, S. A.; Smolov, V. B.

    1986-01-01

    After a classification and analysis of electronic and optoelectronic switching devices, the design principles and structure of a matrix optical switch is described. The switching and pair-exclusion operations in this type of switch are examined, and a method for the optical switching of communication channels is elaborated. Finally, attention is given to the structural organization of a parallel computer system with a matrix optical switch.

  8. The Sarcoglycan complex is expressed in the cerebrovascular system and is specifically regulated by astroglial Cx30 channels.

    PubMed

    Boulay, Anne-Cécile; Saubaméa, Bruno; Cisternino, Salvatore; Mignon, Virginie; Mazeraud, Aurélien; Jourdren, Laurent; Blugeon, Corinne; Cohen-Salmon, Martine

    2015-01-01

    Astrocytes, the most prominent glial cell type in the brain, send specialized processes called endfeet, around blood vessels and express a large molecular repertoire regulating the cerebrovascular system physiology. One of the most striking properties of astrocyte endfeet is their enrichment in gap junction proteins Connexin 43 and 30 (Cx43 and Cx30) allowing in particular for direct intercellular trafficking of ions and small signaling molecules through perivascular astroglial networks. In this study, we addressed the specific role of Cx30 at the gliovascular interface. Using an inactivation mouse model for Cx30 (Cx30(Δ/Δ); Δ means deleted allele) we showed that absence of Cx30 does not affect blood-brain barrier (BBB) organization and permeability. However, it results in the cerebrovascular fraction, in a strong upregulation of Sgcg encoding γ-Sarcoglycan (γ-SG), a member of the Dystrophin-associated protein complex (DAPC) connecting cytoskeleton and the extracellular matrix. The same molecular event occurs in Cx30(T5M/T5M) mutated mice, where Cx30 channels are closed, demonstrating that Sgcg regulation relied on Cx30 channel functions. We further characterized the expression of other Sarcoglycan complex (SGC) molecules in the cerebrovascular system and showed the presence of α-, β-, δ-, γ-, ε- and ζ- SG, as well as Sarcospan. Their expression was however not modified in Cx30(Δ/Δ). These results suggest that a full SGC might be present in the cerebrovascular system, and that expression of one of its member, γ-SG, depends on Cx30 channels. As described in skeletal muscles, the SGC may contribute to membrane stabilization and signal transduction in the cerebrovascular system, which may therefore be regulated by Cx30 channel-mediated functions. PMID:25698924

  9. More than 100 channel supercontinuum CW optical source with precise 25GHz spacing for 10Gbit/s DWDM systems

    NASA Astrophysics Data System (ADS)

    Wang, Jianping; Nan, Yinbo; Zhou, Xianwei

    2006-01-01

    We experimentally demonstrate the generation of supercontinuum (SC) with a 12.5GHz DFB/EAM ultrashort optical pulse broadened in the high nonlinear fiber (HNLF). Through longitudinal mode-carving of the SC spectrum, a novel multiwavelength continuous wave (CW) optical source with precise 25GHz channel spacing is realized. The bit error rate (BER) curve and eye diagram show that the multiwavelength CW optical source is promising for dense wavelength division multiplexing (DWDM) systems.

  10. The Sarcoglycan complex is expressed in the cerebrovascular system and is specifically regulated by astroglial Cx30 channels

    PubMed Central

    Boulay, Anne-Cécile; Saubaméa, Bruno; Cisternino, Salvatore; Mignon, Virginie; Mazeraud, Aurélien; Jourdren, Laurent; Blugeon, Corinne; Cohen-Salmon, Martine

    2015-01-01

    Astrocytes, the most prominent glial cell type in the brain, send specialized processes called endfeet, around blood vessels and express a large molecular repertoire regulating the cerebrovascular system physiology. One of the most striking properties of astrocyte endfeet is their enrichment in gap junction proteins Connexin 43 and 30 (Cx43 and Cx30) allowing in particular for direct intercellular trafficking of ions and small signaling molecules through perivascular astroglial networks. In this study, we addressed the specific role of Cx30 at the gliovascular interface. Using an inactivation mouse model for Cx30 (Cx30Δ/Δ; Δ means deleted allele) we showed that absence of Cx30 does not affect blood-brain barrier (BBB) organization and permeability. However, it results in the cerebrovascular fraction, in a strong upregulation of Sgcg encoding γ-Sarcoglycan (γ-SG), a member of the Dystrophin-associated protein complex (DAPC) connecting cytoskeleton and the extracellular matrix. The same molecular event occurs in Cx30T5M/T5M mutated mice, where Cx30 channels are closed, demonstrating that Sgcg regulation relied on Cx30 channel functions. We further characterized the expression of other Sarcoglycan complex (SGC) molecules in the cerebrovascular system and showed the presence of α-, β-, δ-, γ-, ε- and ζ- SG, as well as Sarcospan. Their expression was however not modified in Cx30Δ/Δ. These results suggest that a full SGC might be present in the cerebrovascular system, and that expression of one of its member, γ-SG, depends on Cx30 channels. As described in skeletal muscles, the SGC may contribute to membrane stabilization and signal transduction in the cerebrovascular system, which may therefore be regulated by Cx30 channel-mediated functions. PMID:25698924

  11. Arroyo channel head evolution in a flash-flood-dominated discontinuous ephemeral stream system

    USGS Publications Warehouse

    DeLong, Stephen B.; Johnson, Joel P.L.; Whipple, Kelin X.

    2014-01-01

    We study whether arroyo channel head retreat in dryland discontinuous ephemeral streams is driven by surface runoff, seepage erosion, mass wasting, or some combination of these hydrogeomorphic processes. We monitored precipitation, overland flow, soil moisture, and headcut migration over several seasonal cycles at two adjacent rangeland channel heads in southern Arizona. Erosion occurred by headward retreat of vertical to overhanging faces, driven dominantly by surface runoff. No evidence exists for erosion caused by shallow-groundwater–related processes, even though similar theater-headed morphologies are sometimes attributed to seepage erosion by emerging groundwater. At our field site, vertical variation in soil shear strength influenced the persistence of the characteristic theater-head form. The dominant processes of erosion included removal of grains and soil aggregates during even very shallow (1–3 cm) overland flow events by runoff on vertical to overhanging channel headwalls, plunge-pool erosion during higher-discharge runoff events, immediate postrunoff wet mass wasting, and minor intra-event dry mass wasting on soil tension fractures developing subparallel to the headwall. Multiple stepwise linear regression indicates that the migration rate is most strongly correlated with flow duration and total precipitation and is poorly correlated with peak flow depth or time-integrated flow depth. The studied channel heads migrated upslope with a self-similar morphologic form under a wide range of hydrological conditions, and the most powerful flash floods were not always responsible for the largest changes in landscape form in this environment. 

  12. Designing Effective Persuasive Systems Utilizing the Power of Entanglement: Communication Channel, Strategy & Affect

    ERIC Educational Resources Information Center

    Li, Haiqing

    2010-01-01

    With rapid advancements in information and communication technologies, computer-mediated communication channels such as email, web, mobile smart-phones with SMS, social networking websites (Facebook), multimedia websites, and OEM devices provide users with multiple technology choices to seek information. However, no study has compared the…

  13. Shale-filled channel system in Wilcox Group (Paleocene-Eocene), north-central south Louisiana

    SciTech Connect

    McCulloh, R.P.; Eversull, L.G.

    1986-09-01

    Anomalously thick shale intervals of limited extent within normally sandy facies of the Wilcox are evident on published regional electric log structure sections through south Louisiana. These intervals were investigated with a series of subregional stratigraphic electric log sections and by mapping. The stratigraphic sections show that in places the shale cuts out nearly 1000 ft (300 m) of adjacent interstratified sandstone and shale section and has lenticular, channel-like, cross-sectional geometry. The sections also indicate that the uppermost parts of the thick shale intervals are stratigraphically equivalent to, or at least contiguous with, a persistent subregional shale marker bed known informally as the Big Shale, but are distinguishable from it in places by more uniform log character. A map of the anomalously thick and uniform shale indicates a south-trending, relatively straight channel with a single bifurcation in southern Avoyelles Parish. The branches probably continue downdip, although they cannot be traced with confidence south of central St. Landry Parish because of the overall shalier Wilcox section and scarcity of adequately deep control wells. The channel shale is analogous to other early Cenozoic subsurface truncational shale masses that have been mostly interpreted as submarine canyon-channel fills. Stratigraphic trapping possibilities are evident from the truncation of bounding permeable units, but the possible continuation of the branches downdip suggests the potential for deep sandy equivalents and deep gas.

  14. Relationships among rotational and conventional grazing systems, stream channels, and macroinvertebrates

    USGS Publications Warehouse

    Raymond, K.L.; Vondracek, B.

    2011-01-01

    Cattle grazing in riparian areas can reduce water quality, alter stream channel characteristics, and alter fish and macroinvertebrate assemblage structure. The U.S. Department of Agriculture, Natural Resources Conservation Services has recommended Rotational Grazing (RG) as an alternative management method on livestock and dairy operations to protect riparian areas and water quality. We evaluated 13 stream channel characteristics, benthic macroinvertebrate larvae (BML), and chironomid pupal exuviae (CPE) from 18 sites in the Upper Midwest of the United States in relation to RG and conventional grazing (CG). A Biotic Composite Score comprised of several macroinvertebrate metrics was developed for both the BML assemblage and the CPE assemblage. Multi-Response Permutation Procedures (MRPP) indicated a significant difference in stream channel characteristics between RG and CG. Nonmetric Multidimensional Scaling indicated that RG sites were associated with more stable stream banks, higher quality aquatic habitat, lower soil compaction, and larger particles in the streambed. However, neither MRPP nor Mann-Whitney U tests demonstrated a difference in Biotic Composite Scores for BML or CPE along RG and CG sites. The BML and CPE metrics were significantly correlated, indicating that they were likely responding to similar variables among the study sites. Although stream channel characteristics appeared to respond to grazing management, BML and CPE may have responded to land use throughout the watershed, as well as local land use. ?? 2011 Springer Science+Business Media B.V. (outside the USA).

  15. The Nile Cone and Its Channel System : New Results From The Fanil Cruise

    NASA Astrophysics Data System (ADS)

    Bellaiche, G.; Loncke, L.; Gaullier, V.; Mascle, J.; Courp, T.; Moreau, A.; Radan, S.; Sardou, O.

    The FANIL cruise (R/V Le Suroit, 2000) completed the knowledge of the Nile Cone, by extending the previous studied areas (PRISMED II cruise, 1998) to the West and to the East. The used method was swath-bathymetry, acoustic imagery, multichannel seismic profiling and coring. Four domains can be clearly identified: A) A western domain shows, upslope, numerous normal growth faults resulting from the spreading of the Plio-Pleistocene sediments on the messinian salt. Beyond, very numerous mud volcanoes are recognized. The Nile deep-sea fan morphology displays a network of meanderous leveed channels showing clear evidence of avulsions and migrations. The westernmost channel is the well marked, and therefore the most recent. But the sam- pled cores show that none of the western channels is still active, since the turbidites are always covered by a thin layer of pelagic sediments. The fan sedimentary structure shows a series of acoustic lense-shaped units interbedded with transparent layers cor- responding to slump deposits. B) A central domain is characterized upslope by 1) very huge debris flow deposits associated with pock-marks to the west and 2) large growth faults to the east. Downslope, salt ridges, approximately oriented N-S, individualize small basins that trap sediments of probably hemipelagic origin. C) An eastern domain comprises a long (> 200 km) NW-SE corridor, bounded by narrow fault zones. Along dip, the corridor exhibits structures typical of salt-bearing passive margins undergoing gravity spreading (distal buckle folds, mid-slope minibasins surrounded by salt ridges, and proximal growth faults). The presence of a passive subsalt relief and/or of a but- tress (the Eratosthenes seamount) has probably caused the peculiar narrow NW-SE fault zones. Upslope, the eastern domain is marked by mud volcanoes and gas seeping tightly associated with faulting. In both central and eastern areas, the Nile meanderous deep-sea channels are still present but highly

  16. Do river channels decrease in width downstream on Distributive Fluvial Systems? An evaluation of modern mega-fans

    NASA Astrophysics Data System (ADS)

    Espinoza, T. N.; Scuderi, L. A.; Weissmann, G. S.; Hartley, A. J.

    2014-12-01

    Recent studies on aggradational continental sedimentary basins globally show that fluvial deposits in most modern sedimentary basins are dominated Distributive Fluvial Systems (DFS). DFS's are identified by: (1) pattern of channels and floodplain deposits that radiate outward from an apex located where the river enters the sedimentary basin, (2) deposition where an alluvial system becomes unconfined upon entering the sedimentary basin, (3) broadly fan shaped deposit that is convex upward across the DFS and concave upward down-fan, and (4) if the DFS is incised, an intersection point above which the alluvial system is held in an incised valley and below which it distributes sediment across an active depositional lobe. Several papers about DFS hypothesized that rivers on DFS decrease in size down-fan. We are testing this hypothesis through evaluation of LANDSAT and STRM data from large DFS described by Hartley et al (2010). We use ArcGIS to: (1) open the images and merge them together if there are more than one image corresponding to the DFS being studied, (2) use a Maximum Likelihood Analysis in six classes to segment different features on the DFS (e.g. exposed sands, water, vegetation, and other fan environments), (3) isolate the classes that correspond to the active channel belt (e.g., exposed sand bars and water), (4) divide the active channel belt into 1000 m long sections, (5) determine the area of active channel belt in each section, and (6) calculate the average width of the river in each section (e.g., W = area/1000m). We present our result for each DFS river on a graph that shows the change in width downstream. Our final product will be a dataset that contains width versus distance down-fan from the apex for as many of the large DFS from Hartley et al (2010) as possible. If the hypothesis is supported, the decrease in width could have a substantial predictive significance on sandstone geometry in fluvial successions.

  17. A deep crustal fluid channel into the San Andreas Fault system near Parkfield, California

    USGS Publications Warehouse

    Becken, M.; Ritter, O.; Park, S.K.; Bedrosian, P.A.; Weckmann, U.; Weber, M.

    2008-01-01

    Magnetotelluric (MT) data from 66 sites along a 45-km-long profile across the San Andreas Fault (SAF) were inverted to obtain the 2-D electrical resistivity structure of the crust near the San Andreas Fault Observatory at Depth (SAFOD). The most intriguing feature of the resistivity model is a steeply dipping upper crustal high-conductivity zone flanking the seismically defined SAF to the NE, that widens into the lower crust and appears to be connected to a broad conductivity anomaly in the upper mantle. Hypothesis tests of the inversion model suggest that upper and lower crustal and upper-mantle anomalies may be interconnected. We speculate that the high conductivities are caused by fluids and may represent a deep-rooted channel for crustal and/or mantle fluid ascent. Based on the chemical analysis of well waters, it was previously suggested that fluids can enter the brittle regime of the SAF system from the lower crust and mantle. At high pressures, these fluids can contribute to fault-weakening at seismogenic depths. These geochemical studies predicted the existence of a deep fluid source and a permeable pathway through the crust. Our resistivity model images a conductive pathway, which penetrates the entire crust, in agreement with the geochemical interpretation. However, the resistivity model also shows that the upper crustal branch of the high-conductivity zone is located NE of the seismically defined SAF, suggesting that the SAF does not itself act as a major fluid pathway. This interpretation is supported by both, the location of the upper crustal high-conductivity zone and recent studies within the SAFOD main hole, which indicate that pore pressures within the core of the SAF zone are not anomalously high, that mantle-derived fluids are minor constituents to the fault-zone fluid composition and that both the volume of mantle fluids and the fluid pressure increase to the NE of the SAF. We further infer from the MT model that the resistive Salinian block

  18. Retrieval of Temperature and Water Vapour From Multiple Channel Lidar Systems Using an Optimal Estimation Method

    NASA Astrophysics Data System (ADS)

    Sica, Robert; Haefele, Alexander

    2015-04-01

    While the application of optimal estimation methods (OEMs) is well-known for the retrieval of atmospheric parameters from passive instruments, active instruments have typically not employed the OEM. For instance, the measurement of temperature in the middle atmosphere with Rayleigh-scatter lidars is an important technique for assessing atmospheric change. Current retrieval schemes for these temperatures have several shortcomings which can be overcome using an OEM. Forward models have been constructed that fully characterize the measurement and allow the simultaneous retrieval of temperature, dead time and background. The OEM allows a full uncertainty budget to be obtained on a per profile basis that includes, in addition to the statistical uncertainties, the smoothing error and uncertainties due to Rayleigh extinction, ozone absorption, the lidar constant, nonlinearity in the counting system, variation of the Rayleigh-scatter cross section with altitude, pressure, acceleration due to gravity and the variation of mean molecular mass with altitude. The vertical resolution of the temperature profile is found at each height, and a quantitative determination is made of the maximum height to which the retrieval is valid. A single temperature profile can be retrieved from measurements with multiple channels that cover different height ranges, vertical resolutions and even different detection methods. The OEM employed is shown to give robust estimates of temperature consistent with previous methods, while requiring minimal computational time. Retrieval of water vapour mixing ratio from vibrational Raman scattering lidar measurements is another example where an OEM offers a considerable advantage over the standard analysis technique, with the same advantages as discussed above for Rayleigh-scatter temperatures but with an additional benefit. The conversion of the lidar measurement into mixing ratio requires a calibration constant to be employed. Using OEM the calibration

  19. Retrieval of Temperature and Water Vapour from Multiple Channel Lidar Systems Using an Optimal Estimation Method

    NASA Astrophysics Data System (ADS)

    Sica, Robert; Haefele, Alexander

    2016-04-01

    While the application of optimal estimation methods (OEMs) is well-known for the retrieval of atmospheric parameters from passive instruments, active instruments have typically not employed the OEM. For instance, the measurement of temperature in the middle atmosphere with Rayleigh-scatter lidars is an important technique for assessing atmospheric change. Current retrieval schemes for these temperatures have several shortcomings which can be overcome using an OEM. Forward models have been constructed that fully characterize the measurement and allow the simultaneous retrieval of temperature, dead time and background. The OEM allows a full uncertainty budget to be obtained on a per profile basis that includes, in addition to the statistical uncertainties, the smoothing error and uncertainties due to Rayleigh extinction, ozone absorption, the lidar constant, nonlinearity in the counting system, variation of the Rayleigh-scatter cross section with altitude, pressure, acceleration due to gravity and the variation of mean molecular mass with altitude. The vertical resolution of the temperature profile is found at each height, and a quantitative determination is made of the maximum height to which the retrieval is valid. A single temperature profile can be retrieved from measurements with multiple channels that cover different height ranges, vertical resolutions and even different detection methods. The OEM employed is shown to give robust estimates of temperature consistent with previous methods, while requiring minimal computational time. Retrieval of water vapour mixing ratio from vibrational Raman scattering lidar measurements is another example where an OEM offers a considerable advantage over the standard analysis technique, with the same advantages as discussed above for Rayleigh-scatter temperatures but with an additional benefit. The conversion of the lidar measurement into mixing ratio requires a calibration constant to be employed. Using OEM the calibration

  20. Climate variability and predictability associated with the Indo-Pacific Oceanic Channel Dynamics in the CCSM4 Coupled System Model

    NASA Astrophysics Data System (ADS)

    Yuan, Dongliang; Xu, Peng; Xu, Tengfei

    2016-03-01

    An experiment using the Community Climate System Model (CCSM4), a participant of the Coupled Model Intercomparison Project phase-5 (CMIP5), is analyzed to assess the skills of this model in simulating and predicting the climate variabilities associated with the oceanic channel dynamics across the Indo-Pacific Oceans. The results of these analyses suggest that the model is able to reproduce the observed lag correlation between the oceanic anomalies in the southeastern tropical Indian Ocean and those in the cold tongue in the eastern equatorial Pacific Ocean at a time lag of 1 year. This success may be largely attributed to the successful simulation of the interannual variations of the Indonesian Throughflow, which carries the anomalies of the Indian Ocean Dipole (IOD) into the western equatorial Pacific Ocean to produce subsurface temperature anomalies, which in turn propagate to the eastern equatorial Pacific to generate ENSO. This connection is termed the "oceanic channel dynamics" and is shown to be consistent with the observational analyses. However, the model simulates a weaker connection between the IOD and the interannual variability of the Indonesian Throughflow transport than found in the observations. In addition, the model overestimates the westerly wind anomalies in the western-central equatorial Pacific in the year following the IOD, which forces unrealistic upwelling Rossby waves in the western equatorial Pacific and downwelling Kelvin waves in the east. This assessment suggests that the CCSM4 coupled climate system has underestimated the oceanic channel dynamics and overestimated the atmospheric bridge processes.

  1. Potential effects of deepening the St. Johns River navigation channel on saltwater intrusion in the surficial aquifer system, Jacksonville, Florida

    USGS Publications Warehouse

    Bellino, Jason C.; Spechler, Rick M.

    2013-01-01

    The U.S. Army Corps of Engineers (USACE) has proposed dredging a 13-mile reach of the St. Johns River navigation channel in Jacksonville, Florida, deepening it to depths between 50 and 54 feet below North American Vertical Datum of 1988. The dredging operation will remove about 10 feet of sediments from the surficial aquifer system, including limestone in some locations. The limestone unit, which is in the lowermost part of the surficial aquifer system, supplies water to domestic wells in the Jacksonville area. Because of density-driven hydrodynamics of the St. Johns River, saline water from the Atlantic Ocean travels upstream as a saltwater “wedge” along the bottom of the channel, where the limestone is most likely to be exposed by the proposed dredging. A study was conducted to determine the potential effects of navigation channel deepening in the St. Johns River on salinity in the adjacent surficial aquifer system. Simulations were performed with each of four cross-sectional, variable-density groundwater-flow models, developed using SEAWAT, to simulate hypothetical changes in salinity in the surficial aquifer system as a result of dredging. The cross-sectional models were designed to incorporate a range of hydrogeologic conceptualizations to estimate the effect of uncertainty in hydrogeologic properties. The cross-sectional models developed in this study do not necessarily simulate actual projected conditions; instead, the models were used to examine the potential effects of deepening the navigation channel on saltwater intrusion in the surficial aquifer system under a range of plausible hypothetical conditions. Simulated results for modeled conditions indicate that dredging will have little to no effect on salinity variations in areas upstream of currently proposed dredging activities. Results also indicate little to no effect in any part of the surficial aquifer system along the cross section near River Mile 11 or in the water-table unit along the cross

  2. Development of information-measuring channels of the monitoring system of quality cut for technological process laser cutting of materials

    NASA Astrophysics Data System (ADS)

    Sukhov, Yuri T.; Matiushin, I. V.

    2001-01-01

    In the paper the researches on development of informational - measuring channels of quality indexes monitoring of laser cutting process with use of acoustic and optical signals of a different range are submitted. The estimations of their information significance and efficiency of use of acoustic and optical signals of a different range are submitted. The estimation of their information significance and efficiency of use are reduced. The structure of the informational - measuring research stand including the basic measuring channels for definition critical by criteria of quality and productivity of process parameters is offered. The carried out researches are aimed to system engineering of monitoring and the quality control of laser cutting processing of materials in real-time mode.

  3. Lateral tunneling through the controlled barrier between edge channels in a two-dimensional electron gas system

    NASA Astrophysics Data System (ADS)

    Shashkin, A. A.; Dolgopolov, V. T.; Deviatov, E. V.; Irmer, B.; Haubrich, A. G. C.; Kotthaus, J. P.; Bichler, M.; Wegscheider, W.

    1999-12-01

    We study the lateral tunneling through the gate-voltage-controlled barrier, which arises as a result of partial elimination of the donor layer of a heterostructure along a fine strip using an atomic force microscope, between edge channels at the depletion-induced edges of a gated two-dimensional electron system. For a sufficiently high barrier a typical current-voltage characteristic is found to be strongly asymmetric and includes, apart from a positive tunneling branch, the negative branch that corresponds to the current overflowing the barrier. We establish that the barrier height depends linearly on both gate voltage and magnetic field and we describe the data in terms of electron tunneling between the outermost edge channels.

  4. Analyzing the benefit of optical transmission systems based on Root Raised Cosine PS-QPSK and a flexible channel grid.

    PubMed

    Seck, A; Ramantanis, P; Vuong, J; Bendimerad, D F; Lepers, C; Benkelfat, B-E; Frignac, Y

    2013-05-01

    We numerically investigate the multi-channel transmission performance of Polarization Switched Quadrature Phase Shift Keying (PS-QPSK) and we compare it to the performance of Polarization-Division-Multiplexed QPSK (PDM-QPSK), using Root Raised Cosine (RRC) spectral shaping, in the context of a flexible channel grid. We point out the impact of the roll-off factor and the potential influence of different dispersion compensation scenarios. Finally, the advantage of PS-QPSK against PDM-QPSK is presented as a function of the system parameters, while we also discuss the benefit of a RRC spectral shaping against a tight filtering at the transmitter side with a 2nd order super-Gaussian-shaped filter. PMID:23669907

  5. Remote, PCM-controlled, multi-channel radio frequency FM telemetry system for cryogenic wind tunnel application

    NASA Technical Reports Server (NTRS)

    Diamond, John K.

    1989-01-01

    A telemetry system used in the NASA-Langley cryogenic transonic wind tunnel to obtain rotational strain and temperature data is described. The system consists of four FM transmitters allowing for a remotely controlled PCM combination. A rotating four-contact mercury slip-ring is used as an interface between the fixed and rotating mechnical structures. Over 60 channels of data on the main fan disk and blade structures have been obtained. These data are studied to verify computer predictions and mechanical life. A series of block diagrams are included.

  6. A Substrate-Fusion Protein Is Trapped inside the Type III Secretion System Channel in Shigella flexneri

    PubMed Central

    Dohlich, Kim; Zumsteg, Anna Brotcke; Goosmann, Christian; Kolbe, Michael

    2014-01-01

    The Type III Secretion System (T3SS) is a macromolecular complex used by Gram-negative bacteria to secrete effector proteins from the cytoplasm across the bacterial envelope in a single step. For many pathogens, the T3SS is an essential virulence factor that enables the bacteria to interact with and manipulate their respective host. A characteristic structural feature of the T3SS is the needle complex (NC). The NC resembles a syringe with a basal body spanning both bacterial membranes and a long needle-like structure that protrudes from the bacterium. Based on the paradigm of a syringe-like mechanism, it is generally assumed that effectors and translocators are unfolded and secreted from the bacterial cytoplasm through the basal body and needle channel. Despite extensive research on T3SS, this hypothesis lacks experimental evidence and the mechanism of secretion is not fully understood. In order to elucidate details of the T3SS secretion mechanism, we generated fusion proteins consisting of a T3SS substrate and a bulky protein containing a knotted motif. Because the knot cannot be unfolded, these fusions are accepted as T3SS substrates but remain inside the NC channel and obstruct the T3SS. To our knowledge, this is the first time substrate fusions have been visualized together with isolated NCs and we demonstrate that substrate proteins are secreted directly through the channel with their N-terminus first. The channel physically encloses the fusion protein and shields it from a protease and chemical modifications. Our results corroborate an elementary understanding of how the T3SS works and provide a powerful tool for in situ-structural investigations in the future. This approach might also be applicable to other protein secretion systems that require unfolding of their substrates prior to secretion. PMID:24453973

  7. Sand dispersal in the southeastern Austral Basin, Tierra del Fuego, Argentina: Outcrop insights from Eocene channeled turbidite systems

    NASA Astrophysics Data System (ADS)

    Torres Carbonell, Pablo J.; Olivero, Eduardo B.

    2012-02-01

    We made a detailed facies analysis of well exposed Eocene foredeep and wedge-top successions in the SE Austral Basin of eastern Tierra del Fuego, Argentina, contributing to a better understanding of its patterns of sand dispersal. The analysis reveals that these successions constitute portions of turbidite systems with recurrent facies associations, interpreted as channel, channel-margin and levée depositional elements. The channel facies, paleocurrents and interpreted paleogeography suggest that the studied successions form the transfer zone of the turbidite systems that fed the foreland basin. We hypothesize that the SE Austral Basin, which forms the transition between the Austral and Malvinas Basins, acted as an east-west conduit for sediments sourced at the Fuegian Andes and transported to a deeper depositional zone in the SW Malvinas Basin. The fill of the channels in the transfer zone involved a large amount of turbidity flows, which in addition to the evidence of levée confinement in the studied deposits suggests that the sandier portion of the flows was able to reach the depositional zone, were mostly unconfined (sheeted) sand bodies may have formed. In addition, overbank sand bodies were deposited within the transfer zone, associated to processes of flow overspill. Both types of sand bodies constitute potential reservoirs in this hydrocarbon producing basin, implying that the Eocene SE Austral Basin, and the ultimate zone of deposition in the SW Malvinas Basin may constitute major prospects for hydrocarbon exploration. The proposed model define a new perspective for future research on the sedimentologic and stratigraphic evolution of the SE portion of the Austral Basin.

  8. The 384-channel prototype of DM Electronics for ELT AO systems

    NASA Astrophysics Data System (ADS)

    Caputa, Kris; Atwood, Jenny; Herriot, Glen; Veran, Jean-Pierre; Spanò, Paolo; Zielinski, Adam

    2014-08-01

    High order AO subsystems of the ELT require technological advancements in the Deformable Mirror (DM) construction and corresponding improvements in the drive electronics. Advanced prototyping is currently under way at NSI-Herzberg to reduce risks of deploying untried technology in the TMT AO subsystem NFIRAOS. We have developed a 96-channel output module and constructed a sub-scale DM Electronics prototype NDME384 with 384 output channels based on 4 such modules. French DM vendor Cilas has fabricated the NFIRAOS DM Breadoboard with 360 piezoelectric actuators in a 60×6 matrix, to demonstrate the DM technology to be deployed in NFIRAOS wavefront correctors. We present the results of testing our NDME384 prototype while driving the NFIRAOS DM Breadoboard.

  9. Design and Simulation of a Matching System into the Helical Cooling Channel

    SciTech Connect

    Yoshikawa, C.; Ankenbrandt, C.; Johnson, R. P.; Kahn, S.; Marhauser, F.; Derbenev, Y.; Morozov, V.; Sy, A.; Alexahin, Y.; Neuffer, D.; Yonehara, K.

    2014-07-01

    Muon colliders could provide the most sensitive measurement of the Higgs mass and return the US back to the Energy Frontier. Central to the capabilities of muon colliders are the cooling channels that provide the extraordinary reduction in emittance required for the precise Higgs mass measurement and increased luminosity for enhanced discovery potential of an Energy Frontier Machine. The Helical Cooling Channel (HCC) is able to achieve such emittance reduction and matching sections within the HCC have been successfully designed in the past with lossless transmission and no emittance growth. However, matching into the HCC from a straight solenoid poses a challenge, since a large emittance beam must cross transition. We elucidate on the challenge and present evaluations of two solutions, along with concepts to integrate the operations of a Charge Separator and match into the HCC.

  10. CHANNEL RESPONSES AND MANAGEMENT STRATEGIES IN DISTURBED CHANNELS: A NUMERICAL SIMULATION APPROACH

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Yalobusha River watershed underwent extensive channelization and channel repositioning during the 1960s. The newly channelized system experienced channel degradation, rejuvenating tributaries and increasing bank heights above stable conditions, causing bank failures and the addition of vegetatio...

  11. Scalable time-correlated photon counting system with multiple independent input channels.

    PubMed

    Wahl, Michael; Rahn, Hans-Jürgen; Röhlicke, Tino; Kell, Gerald; Nettels, Daniel; Hillger, Frank; Schuler, Ben; Erdmann, Rainer

    2008-12-01

    Time-correlated single photon counting continues to gain importance in a wide range of applications. Most prominently, it is used for time-resolved fluorescence measurements with sensitivity down to the single molecule level. While the primary goal of the method used to be the determination of fluorescence lifetimes upon optical excitation by short light pulses, recent modifications and refinements of instrumentation and methodology allow for the recovery of much more information from the detected photons, and enable entirely new applications. This is achieved most successfully by continuously recording individually detected photons with their arrival time and detection channel information (time tagging), thus avoiding premature data reduction and concomitant loss of information. An important property of the instrumentation used is the number of detection channels and the way they interrelate. Here we present a new instrument architecture that allows scalability in terms of the number of input channels while all channels are synchronized to picoseconds of relative timing and yet operate independent of each other. This is achieved by means of a modular design with independent crystal-locked time digitizers and a central processing unit for sorting and processing of the timing data. The modules communicate through high speed serial links supporting the full throughput rate of the time digitizers. Event processing is implemented in programmable logic, permitting classical histogramming, as well as time tagging of individual photons and their temporally ordered streaming to the host computer. Based on the time-ordered event data, any algorithms and methods for the analysis of fluorescence dynamics can be implemented not only in postprocessing but also in real time. Results from recently emerging single molecule applications are presented to demonstrate the capabilities of the instrument. PMID:19123551

  12. A 96 channel receiver for the ILCTA LLRF system at Fermilab

    SciTech Connect

    Mavric, Uros; Chase, Brian; Branlard, Julien; Cullerton, Ed; Klepec, Dan; /Fermilab

    2007-06-01

    The present configuration of an ILC main LINAC RF station has 26 nine cell cavities driven from one klystron. With the addition of waveguide power coupler monitors, 96 RF signals will be down-converted and processed. A down-converter chassis is being developed that contains 12 eight channel analog modules and a single upconverter module. This chassis will first be deployed for testing a cryomodule composed of eight cavities located at New Muon Laboratory (NML) - Fermilab. Critical parts of the design for LLRF applications are identified and a detailed description of the circuit with various characteristic measurements is presented. The board is composed of an input band-pass filter centered at 1.3GHz, followed by a mixer, which down-converts the cavity probe signal to a proposed 13 MHz intermediate frequency. Cables with 8 channels per connector and good isolation between channels are being used to interconnect each down-converter module with a digital board. As mixers, amplifiers and power splitters are the most sensitive parts for noise, nonlinearities and crosstalk issues, special attention is given to these parts in the design of the LO port multiplication and distribution.

  13. Glia and TRPM2 Channels in Plasticity of Central Nervous System and Alzheimer's Diseases

    PubMed Central

    Wang, Jing; Jackson, Michael F.; Xie, Yu-Feng

    2016-01-01

    Synaptic plasticity refers to the ability of neurons to strengthen or weaken synaptic efficacy in response to activity and is the basis for learning and memory. Glial cells communicate with neurons and in this way contribute in part to plasticity in the CNS and to the pathology of Alzheimer's disease (AD), a neurodegenerative disease in which impaired synaptic plasticity is causally implicated. The transient receptor potential melastatin member 2 (TRPM2) channel is a nonselective Ca2+-permeable channel expressed in both glial cells (microglia and astrocytes) and neurons. Recent studies indicated that TRPM2 regulates synaptic plasticity as well as the activation of glial cells. TRPM2 also modulates oxidative stress and inflammation through interaction with glial cells. As both oxidative stress and inflammation have been implicated in AD pathology, this suggests a possible contribution of TRPM2 to disease processes. Through modulating the homeostasis of glutathione, TRPM2 is involved in the process of aging which is a risk factor of AD. These results potentially point TRPM2 channel to be involved in AD through glial cells. This review summarizes recent advances in studying the contribution of TRPM2 in health and in AD pathology, with a focus on contributions via glia cells. PMID:26942016

  14. Glia and TRPM2 Channels in Plasticity of Central Nervous System and Alzheimer's Diseases.

    PubMed

    Wang, Jing; Jackson, Michael F; Xie, Yu-Feng

    2016-01-01

    Synaptic plasticity refers to the ability of neurons to strengthen or weaken synaptic efficacy in response to activity and is the basis for learning and memory. Glial cells communicate with neurons and in this way contribute in part to plasticity in the CNS and to the pathology of Alzheimer's disease (AD), a neurodegenerative disease in which impaired synaptic plasticity is causally implicated. The transient receptor potential melastatin member 2 (TRPM2) channel is a nonselective Ca(2+)-permeable channel expressed in both glial cells (microglia and astrocytes) and neurons. Recent studies indicated that TRPM2 regulates synaptic plasticity as well as the activation of glial cells. TRPM2 also modulates oxidative stress and inflammation through interaction with glial cells. As both oxidative stress and inflammation have been implicated in AD pathology, this suggests a possible contribution of TRPM2 to disease processes. Through modulating the homeostasis of glutathione, TRPM2 is involved in the process of aging which is a risk factor of AD. These results potentially point TRPM2 channel to be involved in AD through glial cells. This review summarizes recent advances in studying the contribution of TRPM2 in health and in AD pathology, with a focus on contributions via glia cells. PMID:26942016

  15. Color DoG: a three-channel color feature detector for embedded systems

    NASA Astrophysics Data System (ADS)

    Fowers, Spencer; Lee, Dah Jye; Wilde, Doran K.

    2010-01-01

    A feature tracker is only as good as the features found by the feature detector. Common feature detectors such as Harris, Sobel, Canny, and Difference of Gaussians convolve an image with a specific kernel in order to identify "corners" or "edges". This convolution requires, however, that the source image contain only one value (or color channel) per pixel. This requirement has reduced the scope of feature detectors, trackers, and descriptors to the set of gray scale (and other single-channel) images. Due to the standard 3-channel RGB representation for color images, highly useful color information is typically discarded or averaged to create a gray scale image that current detectors can operate on. This removes a large amount of useful information from the image. We present in this paper the color Difference of Gaussians algorithm which outperforms the gray scale DoG in number and quality of features found. The color DoG utilizes the YCbCr color space to allow for separated processing of intesity and chrominance values. An embedded vision sensor based on a low power field programmable gate array (FPGA) platform is being developed to process color images using the color DoG with no reduction in processing speed. This low power vision sensor will be well suited for autonomous vehicle applications where size and power consumption are paramount.

  16. Combination of detection and estimation tasks using channelized scanning linear observer for CT imaging systems

    NASA Astrophysics Data System (ADS)

    Tseng, Hsin-Wu; Fan, Jiahua; Kupinski, Matthew A.

    2015-03-01

    Maintaining or even improving image quality while lowering patient dose is always the desire in clinical CT imaging. Iterative reconstruction (IR) algorithms have been designed to help reduce dose and/or provide better image quality. In this work, the channelized scanning linear observer (CSLO) is applied to study the combination of detection and estimation task performance using CT image data. The purpose of this work is to design a task-­-based approach to quantitatively evaluate image-­-quality for different reconstruction algorithms. Low-­-contrast objects embedded in head-­-size and body-­-size phantoms are imaged multiple times and reconstructed by FBP and an IR algorithm for this study. Independent signal present and absent ROIs cropped from images are channelized by Difference of Gauss channels for CSLO training and testing. Estimation receiver operating characteristic (EROC) curves and the area under EROC curve (EAUC) are calculated by CSLO as the figure of merit. The One-­- Shot method is used to compute the variance of the EAUC values. Results suggest that the IR algorithm studied in this work could efficiently reduce the dose approximately 54% to achieve an image quality comparable to conventional FBP reconstruction for the combined detection and estimation tasks.

  17. An experimental study of the concatenated Reed-Solomon/Viterbi channel coding system performance and its impact on space communications

    NASA Technical Reports Server (NTRS)

    Liu, K. Y.; Lee, J. J.

    1981-01-01

    The need for efficient space communication at very low bit error probabilities to the specification and implementation of a concatenated coding system using an interleaved Reed-Solomon code as the outer code and a Viterbi-decoded convolutional code as the inner code. Experimental results of this channel coding system are presented under an emulated S-band uplink and X-band downlink two-way space communication channel, where both uplink and downlink have strong carrier power. This work was performed under the NASA End-to-End Data Systems program at JPL. Test results verify that at a bit error probability of 10 to the -6 power or less, this concatenated coding system does provide a coding gain of 2.5 dB or more over the Viterbi-decoded convolutional-only coding system. These tests also show that a desirable interleaving depth for the Reed-Solomon outer code is 8 or more. The impact of this "virtually" error-free space communication link on the transmission of images is discussed and examples of simulation results are given.

  18. Symmetrization for redundant channels

    NASA Technical Reports Server (NTRS)

    Tulplue, Bhalchandra R. (Inventor); Collins, Robert E. (Inventor)

    1988-01-01

    A plurality of redundant channels in a system each contain a global image of all the configuration data bases in each of the channels in the system. Each global image is updated periodically from each of the other channels via cross channel data links. The global images of the local configuration data bases in each channel are separately symmetrized using a voting process to generate a system signal configuration data base which is not written into by any other routine and is available for indicating the status of the system within each channel. Equalization may be imposed on a suspect signal and a number of chances for that signal to heal itself are provided before excluding it from future votes. Reconfiguration is accomplished upon detecting a channel which is deemed invalid. A reset function is provided which permits an externally generated reset signal to permit a previously excluded channel to be reincluded within the system. The updating of global images and/or the symmetrization process may be accomplished at substantially the same time within a synchronized time frame common to all channels.

  19. Neogene evolution of the Pedro Channel carbonate system, northern Nicaragua Rise

    NASA Astrophysics Data System (ADS)

    Cunningham, Andrew David

    1998-11-01

    Pedro Channel is the deepest, central-most seaway on the northern Nicaragua Rise. A revised bathymetric map illustrates a seafloor dissected by numerous canyons and gullies as well as portions of a drowned carbonate bank with keep-up bank morphology. The 3.5 kHz echogram data interpretation in Pedro Channel indicates the banks provide both a line and point source of sediment to the channel floor. Concentric facies belts along the bank margins illustrate the line source concept. Localized zones of coarser-grained deposits at the bases of canyons along the bank margins depict the point source concept. The synthetic seismograms for ODP Site 1000 have low correlation coefficients (0.321). Visual correlation of the synthetic seismogram with SCS data indicates a good correlation of seismic facies with various lithologic intervals. An interpretation of SCCS and MCS data reveals that periplatform sedimentation has dominated Pedro Channel from the early Miocene to recent. Dredge haul analysis suggests that a neritic carbonate bank drowned partially in the middle Oligocene and finally in the early Miocene. Erosion affects the edges of this drowned bank in the middle Miocene. Faults in Pedro Channel illustrate characteristics typical of sinistral strike-slip faults including vertical to sub-vertical faults, faults that splay upward, forced folds, and linear fault traces in map view. ODP Site 998 was selected over a small portion of the Cayman Rise on a small topographic high. Synthetic seismograms for ODP Site 998 have low correlation coefficients (0.168). Despite the low correlation coefficients, turbidite-rich core intervals correlate with SCS intervals having low continuity seismic reflectors. The predominantly pelagic sedimentation at this Site results in a generally continuous seismic reflection character. ODP Site 1001 is located just north of the Hess Escarpment. Synthetic seismograms have low correlation coefficients (0.335), but do permit correlation of SCS Asp

  20. RF/microwave system high-fidelity modeling and simulation: application to airborne multi-channel receiver system for angle of arrival estimation

    NASA Astrophysics Data System (ADS)

    Wu, Chen; Rajan, Sreeraman; Young, Anne; O'Regan, Christina

    2014-06-01

    In this paper, a high-fidelity RF modeling and simulation framework is demonstrated to model an airborne multi-channel receiver system that is used to estimate the angle of arrival (AoA) of received signals from a stationary emitter. The framework is based on System Tool Kit (STK®), Matlab and SystemVue®. The SystemVue-based multi-channel receiver estimates the AoA of incoming signals using adjacent channel amplitude and phase comparisons, and it estimates the Doppler frequency shift of the aircraft by processing the transmitted and received signals. The estimated AoA and Doppler frequency are compared with the ground-truth data provided by STK to validate the efficacy of the modeling process. Unlike other current RF electronic warfare simulation frameworks, the received signal described herein is formed using the received power, the propagation delay and the transmitted waveform, and does not require information such as Doppler frequency shift or radial velocity of the moving platform from the scenario; hence, the simulation is more computationally efficient. In addition, to further reduce the overall modeling and simulation time, since the high-fidelity model computation is costly, the high-fidelity electronic system model is evoked only when the received power is higher than a predetermined threshold.

  1. Improved ankle and knee control with a dual-channel functional electrical stimulation system in chronic hemiplegia. A case report.

    PubMed

    Springer, S; Khamis, S; Laufer, Y

    2014-04-01

    The aim of tis report is to describe the effects of a dual-channel functional electrical stimulation (FES) system applied daily as an orthotic device to the dorsiflexors and hamstrings muscles in a subject with chronic hemiparesis. Prior to the application of FES, the patient's gait was characterized by a footdrop and knee hyperextension during stance. measurements of gait performance were collected before FES application, after a conditioning period of six weeks, and following ten months of daily use. Outcomes included lower limb kinematics and temporal gait measures. The kinematic assessments indicated significant benefits for gait with the dorsiflexors and hamstrings FES, as compared to no stimulation and peroneal FES alone. In addition ot improved ankle control, knee hyperextension was reduced during stance, and the self-selected comfortable gait velocity increased following ten months of daily use. The results of this report suggest that dual-channel FES for the dorsiflexors and hamstrings muscles may affect ankle and knee control beyond that witch can be attributed to peroneal stimulation alone. The positive effects observed in this case study point to the potential of dual-channel FES as a viable treatment options in the rehabilitation of patients with similar impairments. PMID:24967447

  2. Generating double emulsions W/O/W in a PDMS system by controlling locally the wetting properties of the channel

    NASA Astrophysics Data System (ADS)

    Willaime, Herve; Pannacci, Nicolas; Grasland-Mongrain, Pol; Soares, Emilie-Marie; Benzaquen, Michael; Tabeling, Patrick

    2008-11-01

    In microfluidic systems, it has been shown that wetting properties of the wall of the microchannel are of crucial importance for the generation of emulsions [1]: to generate an emulsion in a fluid, the continuous phase must wet the walls of the channel better than the dispersed phase. In the particular case of alternate double emulsions (water in oil in water), it is necessary to pattern the wetting properties of the channel. In this paper, we present preliminary works on the control of wetting properties on PDMS microchannels for the generation of double emulsion. The method we have chosen is inspired by the works of Allbritton [2] and Kumacheva [3] by UV-grafting a hydrophilic polymer onto the surface inside the microchannel. Once the channels are grafted, it is possible to obtain alternate double emulsions. We will present the objects obtained with such microchannels and will focus on their structures and on their stabilities. [1]^ Dreyfus R., Tabeling P., Willaime H., Physical Review Letters, 2003, 90(14). [2] Hu S., Ren X., Bachman M., Sims C., Li G.P., Allbritton N. Anal. Chem. 2004, 76, 1865-1870 [3] Seo M., Paquet C., Nie Z., Xua S., Kumacheva E. Soft Matter, 2007, 3, 986--992

  3. A decision support system for real-time management of dissolvedoxygen in the Stockton deep water ship channel

    SciTech Connect

    Quinn, N.W.T.; Chen, Carl W.; Stringfellow, William T.

    2003-07-16

    A decision support system(DSS)is under development to assistin the control and management of episodes of dissolved oxygen sag in aDeep Water Ship Channel (DWSC), located in Stockton, California. The DWSCwas formed by excavating the bed of the San Joaquin River in the 1950'sto allow navigation by ocean-going cargo ships to the Port of Stockton.The deepened channel has the effect of increasing hydraulic residencetime by a factor of ten. allowing accumulation of decaying algae andother oxygen demanding substances - which creates a barrier to themigration of anadromous fish. This problem, which manifests itself inlate summer and early autumn, is an impediment to a multimillion dollarhabitat restoration effort for the salmon fishery in the San JoaquinRiver basin (SJRB). A hydrodynamic and water quality model of the Deltaand San Joaquin River forms the basis of the DSS which will provideforecasts of dissolved oxygen sag in the DWSC and provide modelingsupport for management actions such as forced aeration to improvedissolved oxygen concentrations in the Ship Channel. A graphical userinterlace, currently used for displaying flow and salinity forecasts onthe San Joaquin River, is being adapted to allow the display of dissolvedoxygen forecasts and to encourage the formation of a stakeholder-ledentity or institution to adaptively manage the problem.

  4. Depositional architecture and evolution of the Late Miocene slope channel-fan-system in the northeastern shelf-margin of South China Sea

    NASA Astrophysics Data System (ADS)

    Jiang, Jing; Lin, Changsong; Zhang, Zhongtao; Tian, Hongxun; Tao, Ze; Liu, Hanyao

    2016-04-01

    The Upper Miocene in the Pearl River Mouth Basin of northwestern shelf-margin of South China Sea Basin contains a series of slope channel - fan systems. Their depositional architecture and evolution are documented in this investigation based on an integrated analysis of cores, logs, and seismic data. Four depositional-palaeogeomorphological elements have been identified in the slope channel-fan systems as follows: broad, shallow and unconfined or partly confined outer-shelf to shelf-break channels; deeply incised and confined unidirectionally migrating slope channels; broad or U-shaped, unconfined erosional-depositional channels; frontal splays-lobes and nonchannelized sheets. The slope channels are mostly oriented NW-SE, which migrated unidirectionally northeastwards and intensively eroded almost the whole shelf-slope zone. The channel infillings are mainly mudstones, interbedded with siltstones. They might be formed by gravity flow erosion as bypassing channels. They were filled with limited gravity flow sediments at the base and mostly filled with lateral accretionary packages of bottom current deposits. At the end of the channels, a series of small-scale slope fans developed and coalesced into fan aprons along the base of the slope. The unconfined erosional-depositional channels at the upper parts of the fan-apron-systems display compound infill patterns, and commonly have concave erosional bases and convex tops. The frontal splays-lobes representing middle to distal deposits of fan-apron-systems have flat-mounded or gull-wing geometries, and the internal architectures include bidirectional downlap, progradation, and chaotic infillings. The distal nonchannelized turbidite sheets are characterized by thin-bedded, parallel to sub-parallel sheet-like geometries. Three major unconformities or obvious erosional surfaces in the channel-fan systems of the Upper Miocene are recognized, and indicate the falling of sea-level. The depositional architecture of sequences

  5. Experimental Investigation and Flow Process Computer Simulation of the Single Mini Channel Condenser for Vapor Compression Refrigeration System

    NASA Astrophysics Data System (ADS)

    Pabilona, L. L.; Villanueva, E. P.

    2015-09-01

    This study is a computer simulation of the temperature profiles and experimental investigation of three 100 mm x 50 mm x 18 mm single mini channel condensers with hydraulic diameters of 3 mm, 2 mm, and 1mm. The mini channels which were made of copper were designed, fabricated and tested. Each unit was connected in a vapor compression cycle with R-134a as the refrigerant. The average refrigerant mass flow rates were varied from 1.296 - 69.471 g/s, and the average inlet and outlet condenser pressure variations were 102.5 - 121.8 kPa and 101.74 -121.23 kPa, respectively. Each condenser was placed inside a mini wind tunnel system where forced draft air was introduced to initiate convective heat transfer. Each condenser was tested and data were gathered every five minute interval for one hour using a Lab View Software. Computer simulations on the flow process were conducted using Solid Works software. The experimental results presented the inlet and outlet condenser pressures, and pressure drops. The experimental heat transfer coefficients were calculated at different mass fluxes during condensation. The values ranged from 3900 to 5200 W/m2-°K for the 3 mm, 2600 to 9000 W/m2-°K for the 2 mm, and 13 to 98 W/m2-°K for the 1 mm. The heat transfer coefficients calculated from experiments were then compared with the computed values using the correlations developed by Dittus-Boelter and Lee-Son. The results showed increasing deviation as the diameter decreased. The discrepancies could be attributed to the appropriateness of the Dittus-Boelter and Lee-Son correlations in small diameter channels, complexities in the flow process which involved two phase flow heat transfer in very small tubes, and the difficulties in attaining very accurate measurements in small channels.

  6. Deep-sea channel/submarine-yazoo system of the Labrador Sea: A new deep-water facies model

    SciTech Connect

    Hesse, R.; Rakofsky, A. )

    1992-05-01

    The deep-sea channel/submarine-yazoo system is a newly recognized deep-water depositional environment that is significantly different from previously documented turbidite environments. The new system is in many ways the antithesis of classical deep-sea fans. The purpose of this paper is to present the characteristics and elements of the system, develop a facies model for it, establish the system variables, and discuss its possible significance in the geologic record and in subsurface exploration. Previous investigators of deepwater turbidite sediments often faced difficulties in trying to fit their sequences into traditional single-source, deep-sea fan models. The present model fills part of an obvious gap in interpretation schemes for deep-water clastic sediments.

  7. The effects of receiver tracking phase error on the performance of the concatenated Reed-Solomon Viterbi channel coding system

    NASA Technical Reports Server (NTRS)

    Liu, K. Y.; Woo, K. T.

    1980-01-01

    In connection with attempts to achieve very low error probabilities, Odenwalder (1970) proposed a concatenated coding system using the Viterbi-decoded convolutional codes as the inner code and Reed-Solomon (RS) codes as the outer code. Analytical and experimental results are presented concerning the effects of the receiver tracking phase error on the performance of the concatenated RS/Viterbi channel coding system. On the basis of these results it is concluded that certain problems regarding communication operations on deep-space missions can be alleviated by employing the RS/Viterbi coding system. In one-way communication, an employment of RS/Viterbi coding will also provide greater data protection than the Viterbi-decoded convolutional-only coding system.

  8. Performance analysis of short-range NLOS UV communication system using Monte Carlo simulation based on measured channel parameters.

    PubMed

    Luo, Pengfei; Zhang, Min; Han, Dahai; Li, Qing

    2012-10-01

    The research presented in this paper is a performance study of short-range NLOS ultraviolet (UV) communication system, using a Monte-Carlo-based system-level model, in which the channel parameters, such as the path loss and the background noise are experimentally measured using an outdoor UV communication test-bed. Various transceiver geometry and background noise condition are considered. Furthermore, 4 modulation schemes are compared, which provides an insight into the performance prediction and the system trade-offs among the path loss, the optical power, the distance, the link geometry, the bit rate and the bit error rate. Finally, advices are given on UV system design and performance improvement. PMID:23188312

  9. Lithologic and hydrologic controls of mixed alluvial-bedrock channels in flood-prone fluvial systems: bankfull and macrochannels in the Llano River watershed, central Texas, USA

    USGS Publications Warehouse

    Heitmuller, Frank T.; Hudson, Paul F.; Asquith, William H.

    2015-01-01

    The rural and unregulated Llano River watershed located in central Texas, USA, has a highly variable flow regime and a wide range of instantaneous peak flows. Abrupt transitions in surface lithology exist along the main-stem channel course. Both of these characteristics afford an opportunity to examine hydrologic, lithologic, and sedimentary controls on downstream changes in channel morphology. Field surveys of channel topography and boundary composition are coupled with sediment analyses, hydraulic computations, flood-frequency analyses, and geographic information system mapping to discern controls on channel geometry (profile, pattern, and shape) and dimensions along the mixed alluvial-bedrock Llano River and key tributaries. Four categories of channel classification in a downstream direction include: (i) uppermost ephemeral reaches, (ii) straight or sinuous gravel-bed channels in Cretaceous carbonate sedimentary zones, (iii) straight or sinuous gravel-bed or bedrock channels in Paleozoic sedimentary zones, and (iv) straight, braided, or multithread mixed alluvial–bedrock channels with sandy beds in Precambrian igneous and metamorphic zones. Principal findings include: (i) a nearly linear channel profile attributed to resistant bedrock incision checkpoints; (ii) statistically significant correlations of both alluvial sinuosity and valley confinement to relatively high f (mean depth) hydraulic geometry values; (iii) relatively high b (width) hydraulic geometry values in partly confined settings with sinuous channels upstream from a prominent incision checkpoint; (iv) different functional flow categories including frequently occurring events (< 1.5-year return periods) that mobilize channel-bed material and less frequent events that determine bankfull channel (1.5- to 3-year return periods) and macrochannel (10- to 40-year return periods) dimensions; (v) macrochannels with high f values (most ≤ 0.45) that develop at sites with unit stream power values in excess

  10. Lithologic and hydrologic controls of mixed alluvial-bedrock channels in flood-prone fluvial systems: Bankfull and macrochannels in the Llano River watershed, central Texas, USA

    NASA Astrophysics Data System (ADS)

    Heitmuller, Franklin T.; Hudson, Paul F.; Asquith, William H.

    2015-03-01

    The rural and unregulated Llano River watershed located in central Texas, USA, has a highly variable flow regime and a wide range of instantaneous peak flows. Abrupt transitions in surface lithology exist along the main-stem channel course. Both of these characteristics afford an opportunity to examine hydrologic, lithologic, and sedimentary controls on downstream changes in channel morphology. Field surveys of channel topography and boundary composition are coupled with sediment analyses, hydraulic computations, flood-frequency analyses, and geographic information system mapping to discern controls on channel geometry (profile, pattern, and shape) and dimensions along the mixed alluvial-bedrock Llano River and key tributaries. Four categories of channel classification in a downstream direction include: (i) uppermost ephemeral reaches, (ii) straight or sinuous gravel-bed channels in Cretaceous carbonate sedimentary zones, (iii) straight or sinuous gravel-bed or bedrock channels in Paleozoic sedimentary zones, and (iv) straight, braided, or multithread mixed alluvial-bedrock channels with sandy beds in Precambrian igneous and metamorphic zones. Principal findings include: (i) a nearly linear channel profile attributed to resistant bedrock incision checkpoints; (ii) statistically significant correlations of both alluvial sinuosity and valley confinement to relatively high f (mean depth) hydraulic geometry values; (iii) relatively high b (width) hydraulic geometry values in partly confined settings with sinuous channels upstream from a prominent incision checkpoint; (iv) different functional flow categories including frequently occurring events (< 1.5-year return periods) that mobilize channel-bed material and less frequent events that determine bankfull channel (1.5- to 3-year return periods) and macrochannel (10- to 40-year return periods) dimensions; (v) macrochannels with high f values (mostly ≥ 0.45) that develop at sites with unit stream power values in excess

  11. Large eddy simulation of compressible turbulent channel and annular pipe flows with system and wall rotations

    NASA Astrophysics Data System (ADS)

    Lee, Joon Sang

    The compressible filtered Navier-Stokes equations were solved using a second order accurate finite volume method with low Mach number preconditioning. A dynamic subgrid-scale stress model accounted for the subgrid-scale turbulence. The study focused on the effects of buoyancy and rotation on the structure of turbulence and transport processes including heat transfer. Several different physical arrangements were studied as outlined below. The effects of buoyancy were first studied in a vertical channel using large eddy simulation (LES). The walls were maintained at constant temperatures, one heated and the other cooled. Results showed that aiding and opposing buoyancy forces emerge near the heated and cooled walls, respectively. In the aiding flow, the turbulent intensities and heat transfer were suppressed at large values of Grashof number. In the opposing flow, however, turbulence was enhanced with increased velocity fluctuations. Another buoyancy study considered turbulent flow in a vertically oriented annulus. Isoflux wall boundary conditions with low and high heating were imposed on the inner wall while the outer wall was adiabatic. The results showed that the strong heating and buoyancy force caused distortions of the flow structure resulting in reduction of turbulent intensities, shear stress, and turbulent heat flux, particularly near the heated wall. Flow in an annular pipe with and without an outer wall rotation about its axis was first investigated at moderate Reynolds numbers. When the outer pipe wall was rotated, a significant reduction of turbulent kinetic energy was realized near the rotating wall. Secondly, a large eddy simulation has been performed to investigate the effect of swirl on the heat and momentum transfer in an annular pipe flow with a rotating inner wall. The simulations indicated that the Nusselt number and the wall friction coefficient increased with increasing rotation speed of the wall. It was also observed that the axial velocity

  12. Generalized channeled polarimetry.

    PubMed

    Alenin, Andrey S; Tyo, J Scott

    2014-05-01

    Channeled polarimeters measure polarization by modulating the measured intensity in order to create polarization-dependent channels that can be demodulated to reveal the desired polarization information. A number of channeled systems have been described in the past, but their proposed designs often unintentionally sacrifice optimality for ease of algebraic reconstruction. To obtain more optimal systems, a generalized treatment of channeled polarimeters is required. This paper describes methods that enable handling of multi-domain modulations and reconstruction of polarization information using linear algebra. We make practical choices regarding use of either Fourier or direct channels to make these methods more immediately useful. Employing the introduced concepts to optimize existing systems often results in superficial system changes, like changing the order, orientation, thickness, or spacing of polarization elements. For the two examples we consider, we were able to reduce noise in the reconstruction to 34.1% and 57.9% of the original design values. PMID:24979633

  13. The Kongsfjorden Channel System offshore NW Spitsbergen, European Arctic: evidence of down-slope processes in a contour-current dominated setting on the continental margin

    NASA Astrophysics Data System (ADS)

    Forwick, Matthias; Sverre Laberg, Jan; Hass, H. Christian; Osti, Giacomo

    2016-04-01

    The Kongsfjorden Channel System (KCS) is located on the continental slope in the eastern Fram Strait, off northwest Spitsbergen. It provides evidence that the influence of down-slope sedimentary processes locally exceeds regional along-slope sedimentation. Compared to other submarine channel systems on and off glaciated continental margins, it is a relatively short system (~120 km) occurring at a large range of water depths (~250-4000 m). It originates with multiple gullies on the Kongsfjorden Trough Mouth Fan merging to small channels that further downslope merge to a main channel. The overall location of the channel system is controlled by variations in slope gradients (0-20°) and the ambient regional bathymetry: widest and deepest incisions occur in areas of steepest slope gradients. The KCS has probably been active since ~1 Ma when glacial activity on Svalbard increased and grounded ice expanded to the shelf break off Kongsfjorden repeatedly. Activity within the system was probably highest during glacials. However, reduced activity presumably took place also during interglacials. The presentation summarizes the work of Forwick et al. (2015). Reference: Forwick, M., Laberg, J.S., Hass, H.C. & Osti, C., 2015. The Kongsfjorden Channel System offshore NW Svalbard: downslope sedimentary processes in a contour-current-dominated setting. Arktos 1, DOI: 10.1007/s41063-015-0018-4.

  14. Long-term high frequency phytoplankton dynamics, recorded from a coastal water autonomous measurement system in the eastern English Channel

    NASA Astrophysics Data System (ADS)

    Derot, J.; Schmitt, F. G.; Gentilhomme, V.; Zongo, S. B.

    2015-10-01

    In this paper, high frequency fluorescence fluctuations, recorded from 2004 to 2011 using an autonomous underwater monitoring system in the eastern English Channel, at 20-min time resolutions, are analyzed. Annual blooms are superposed to multiscale fluctuations. The probability density function (pdf) of the fluorescence time series obeys a power law with slope -2. The pdf for annual portions also obeys power laws, with slopes related to the annual average. Empirical mode decomposition (EMD) is used to study the dynamics and display the power spectrum, which is different from the temperature power spectrum. EMD is also used to extract a trend and isolate the blooms from the high frequency dynamics.

  15. Catastrophic flooding origin of shelf valley systems in the English Channel.

    PubMed

    Gupta, Sanjeev; Collier, Jenny S; Palmer-Felgate, Andy; Potter, Graeme

    2007-07-19

    Megaflood events involving sudden discharges of exceptionally large volumes of water are rare, but can significantly affect landscape evolution, continental-scale drainage patterns and climate change. It has been proposed that a significant flood event eroded a network of large ancient valleys on the floor of the English Channel-the narrow seaway between England and France. This hypothesis has remained untested through lack of direct evidence, and alternative non-catastrophist ideas have been entertained for valley formation. Here we analyse a new regional bathymetric map of part of the English Channel derived from high-resolution sonar data, which shows the morphology of the valley in unprecedented detail. We observe a large bedrock-floored valley that contains a distinct assemblage of landforms, including streamlined islands and longitudinal erosional grooves, which are indicative of large-scale subaerial erosion by high-magnitude water discharges. Our observations support the megaflood model, in which breaching of a rock dam at the Dover Strait instigated catastrophic drainage of a large pro-glacial lake in the southern North Sea basin. We suggest that megaflooding provides an explanation for the permanent isolation of Britain from mainland Europe during interglacial high-sea-level stands, and consequently for patterns of early human colonisation of Britain together with the large-scale reorganization of palaeodrainage in northwest Europe. PMID:17637667

  16. A 20-Channel Receive-Only Mouse Array Coil for a 3T Clinical MRI System

    PubMed Central

    Keil, Boris; Wiggins, Graham C.; Triantafyllou, Christina; Wald, Lawrence L.; Meise, Florian M.; Schreiber, Laura M.; Klose, Klaus J.; Heverhagen, Johannes T.

    2010-01-01

    A 20-channel phased-array coil for Magnetic Resonance Imaging (MRI) of mice has been designed, constructed and validated with bench measurements and high resolution accelerated imaging. The technical challenges of designing a small, high density array have been overcome using individual small-diameter coil elements arranged on a cylinder in a hexagonal overlapping design with adjacent low impedance preamplifiers to further decouple the array elements. Signal-to-noise ratio (SNR) and noise amplification in accelerated imaging were simulated and quantitatively evaluated in phantoms and in vivo mouse images. Comparison between the 20-channel mouse array and a length-matched quadrature driven small animal birdcage coil showed an SNR increase at the periphery and in the center of the phantom of 3-fold and 1.3-fold, respectively. Comparison to a shorter but SNR-optimized birdcage coil (aspect ratio 1:1 and only half mouse coverage) showed an SNR gain of 2-fold at the edge of the phantom and similar SNR in the center. G-factor measurements indicate that the coil is well suited to acquire highly accelerated images. PMID:21433066

  17. Dissection of the peripheral motion channel in the visual system of Drosophila melanogaster.

    PubMed

    Rister, Jens; Pauls, Dennis; Schnell, Bettina; Ting, Chun-Yuan; Lee, Chi-Hon; Sinakevitch, Irina; Morante, Javier; Strausfeld, Nicholas J; Ito, Kei; Heisenberg, Martin

    2007-10-01

    In the eye, visual information is segregated into modalities such as color and motion, these being transferred to the central brain through separate channels. Here, we genetically dissect the achromatic motion channel in the fly Drosophila melanogaster at the level of the first relay station in the brain, the lamina, where it is split into four parallel pathways (L1-L3, amc/T1). The functional relevance of this divergence is little understood. We now show that the two most prominent pathways, L1 and L2, together are necessary and largely sufficient for motion-dependent behavior. At high pattern contrast, the two pathways are redundant. At intermediate contrast, they mediate motion stimuli of opposite polarity, L2 front-to-back, L1 back-to-front motion. At low contrast, L1 and L2 depend upon each other for motion processing. Of the two minor pathways, amc/T1 specifically enhances the L1 pathway at intermediate contrast. L3 appears not to contribute to motion but to orientation behavior. PMID:17920022

  18. Q-ary collision resolution algorithms in random-access systems with free or blocked channel access

    NASA Astrophysics Data System (ADS)

    Mathys, P.; Flajolet, P.

    1985-03-01

    The throughput characteristics of contention-based random-access systems (RAS's) which use Q-ary tree algorithms (where Q equal to or greater than 2 is the number of groups into which contending users are split) of the Capetanakis-Tsybakov-Mikhailov-Vvedenskaya type are analyzed for an infinite population of identical users generating packets according to a Poisson process. Both free and blocked channel-access protocols are considered in combination with Q-ary collision resoluton algorithms that exploit either binary ('collision/no collision') or ternary ('collision/success/idle') feedback. For the resulting RAS's, functional equations for transformed generating functions of the first two moments of the collision resolution interval length are obtained and solved. The maximum stable throughput as a function of Q is given. The results of a packet-delay analysis are also given, and the analyzed RAS's are compared among themselves and with the slotted ALOHA system in terms of both system throughput and packet delay. It is concluded that the 'practical optimum' RAS (in terms of ease of implementation combined with good performance) uses free (i.e., immediate) channel access and ternary splitting (i.e., Q = 3) with binary feedback.

  19. A Bed Load Monitoring System for Real Time Sediment Transport and Bed Morphology during Channel Altering Events

    NASA Astrophysics Data System (ADS)

    Curran, J. C.; Waters, K. A.; Cannatelli, K.

    2014-12-01

    A new technique is presented that provides continuous measurement of sediment movement over the length of a flume. Real-time measurements of bed changes over a reach are a missing piece needed to link bed morphology with sediment transport processes during unsteady flows when the bed adjusts quickly to changing transport rates or visual observation of the bed is precluded by fine sediment in the water column. A bed load monitoring system (BLMS) was developed that records the sediment and water loads over discrete bed lengths throughout a flow event. It was designed for laboratory application where controlled measurement methods are possible. Upon data processing, the BLMS provides a continuous measure of the sediment load across the bed from which sediment movement rates through the reach, including areas of temporary aggradation or degradation, can be reconstructed. Examples are provided of how the bed load monitoring system has been applied during sediment feed and sediment recirculation experiments to further the interpretation of channel processes occurring during large flows. We detail the use of the BLMS to measure bed slopes during unsteady flows and to measure the movement of sediment downstream following different methods of dam removal. We evaluate the BLMS for use where DEM differencing was also applied to illustrate the information provided by each measurement method. Exciting implications of future research that incorporates a BLMS include a more informed management of river systems as a result of improved temporal predictions of sediment movement and the associated changes in channel slope and morphology.

  20. Modified Fletcher's 3-channel brachytherapy system with vaginal line source loading versus uterine tandem and vaginal cylinder system in Stage IIIA cervical cancer

    PubMed Central

    Low, JSH; Ng, KB

    2006-01-01

    Purpose The uterine tandem with open-ended vaginal cylinder is the most commonly used brachytherapy system for Federation Internationale de Gynecologie et d'Obstetrique (FIGO) Stage IIIA cervix cancer at the National Cancer Centre, Singapore. Without the 3-channel ovoid system, the dose to the parametrium is often compromised. In this study, a vaginal cylinder that could potentially be incorporated with the 3-channel system was developed, hence addressing the problem of treating both the vaginal disease extension and the parametrium. Methods and materials A hollow cylinder of 3 cm in diameter was incorporated with the Fletcher's 3-channel tandem and ovoid system. Treatment plans were generated with the single tandem line source with a vaginal cylinder applicator and the modified Fletcher's system using the Abacus version 3 brachytherapy treatment planning software. A nominal dose of 5 Gy was prescribed to point H for both plans. The perpendicular distance of the 5 Gy isodose line from the uterine tandem plane at the centre of the ovoid and the vaginal cylinder plane 1 cm below the os guard were then compared. Results The 5 Gy isodose line was 1.7 cm from the uterine tandem source at the location lateral through the centre of the ovoids on the plan with the uterine tandem and vaginal cylinder system as compared to a distance of 3.3 cm using the modified 3-channel Fletcher system. The 5 Gy isodose line was 2 cm lateral to the central source at the vaginal cylinder plane 1 cm below the os guard on the uterine tandem and vaginal cylinder system as compared to a distance of 2.5 cm on the Modified-Fletcher system. This corresponds to an increase of 1.6 cm and 0.5 cm depth of treated parametrium on the uterine tandem plane and vaginal cylinder plane respectively with the modified Fletcher's applicator as compared with the single line source cylinder system. Conclusion As compared with the single uterine tandem and open-ended vaginal cylinder system, an addition of 1.6 cm

  1. Measurements and coupled reaction channels analysis of one- and two-proton transfer reactions for the 28Si + 90,94Zr systems

    NASA Astrophysics Data System (ADS)

    Kalkal, Sunil; Mandal, S.; Jhingan, A.; Gehlot, J.; Sugathan, P.; Golda, K. S.; Madhavan, N.; Garg, Ritika; Goyal, Savi; Mohanto, Gayatri; Sandal, Rohit; Chakraborty, Santosh; Verma, Shashi; Behera, Bivash; Eleonora, G.; Wollersheim, H. J.; Singh, R.

    2012-03-01

    Measurements of angular distributions for one- and two-proton stripping reactions for 28Si + 90,94Zr systems were performed at 120 MeV. The experiment was carried out with the 28Si beam at Inter University Accelerator Center, New Delhi. The theoretical calculations were performed using the quantum mechanical coupled reaction channels code fresco. The distorted wave Born approximation calculations reproduced the experimental angular distributions for the one-proton transfer channel for both the systems reasonably well but failed for the two-proton transfer channel. Coupled channels calculations including various intermediate states (involving target and projectile inelastic excitations before and/or after transfer) along with the sequential transfer were able to reproduce the two-proton transfer angular distributions for both the systems reasonably well. It seems that at an energy above the Coulomb barrier, there is significant contribution of the indirect multistep and sequential transfer to the two-proton stripping reaction.

  2. Transient and big are key features of an invertebrate T-type channel (LCav3) from the central nervous system of Lymnaea stagnalis.

    PubMed

    Senatore, Adriano; Spafford, J David

    2010-03-01

    Here we describe features of the first non-mammalian T-type calcium channel (LCa(v)3) expressed in vitro. This molluscan channel possesses combined biophysical properties that are reminiscent of all mammalian T-type channels. It exhibits T-type features such as "transient" kinetics, but the "tiny" label, usually associated with Ba(2+) conductance, is hard to reconcile with the "bigness" of this channel in many respects. LCa(v)3 is 25% larger than any voltage-gated ion channel expressed to date. It codes for a massive, 322-kDa protein that conducts large macroscopic currents in vitro. LCa(v)3 is also the most abundant Ca(2+) channel transcript in the snail nervous system. A window current at typical resting potentials appears to be at least as large as that reported for mammalian channels. This distant gene provides a unique perspective to analyze the structural, functional, drug binding, and evolutionary aspects of T-type channels. PMID:20056611

  3. Channel Efficiency with Security Enhancement for Remote Condition Monitoring of Multi Machine System Using Hybrid Huffman Coding

    NASA Astrophysics Data System (ADS)

    Datta, Jinia; Chowdhuri, Sumana; Bera, Jitendranath

    2015-07-01

    This paper presents a novel scheme of remote condition monitoring of multi machine system where a secured and coded data of induction machine with different parameters is communicated between a state-of-the-art dedicated hardware Units (DHU) installed at the machine terminal and a centralized PC based machine data management (MDM) software. The DHUs are built for acquisition of different parameters from the respective machines, and hence are placed at their nearby panels in order to acquire different parameters cost effectively during their running condition. The MDM software collects these data through a communication channel where all the DHUs are networked using RS485 protocol. Before transmitting, the parameter's related data is modified with the adoption of differential pulse coded modulation (DPCM) and Huffman coding technique. It is further encrypted with a private key where different keys are used for different DHUs. In this way a data security scheme is adopted during its passage through the communication channel in order to avoid any third party attack into the channel. The hybrid mode of DPCM and Huffman coding is chosen to reduce the data packet length. A MATLAB based simulation and its practical implementation using DHUs at three machine terminals (one healthy three phase, one healthy single phase and one faulty three phase machine) proves its efficacy and usefulness for condition based maintenance of multi machine system. The data at the central control room are decrypted and decoded using MDM software. In this work it is observed that Chanel efficiency with respect to different parameter measurements has been increased very much.

  4. Fading channel simulator

    DOEpatents

    Argo, Paul E.; Fitzgerald, T. Joseph

    1993-01-01

    Fading channel effects on a transmitted communication signal are simulated with both frequency and time variations using a channel scattering function to affect the transmitted signal. A conventional channel scattering function is converted to a series of channel realizations by multiplying the square root of the channel scattering function by a complex number of which the real and imaginary parts are each independent variables. The two-dimensional inverse-FFT of this complex-valued channel realization yields a matrix of channel coefficients that provide a complete frequency-time description of the channel. The transmitted radio signal is segmented to provide a series of transmitted signal and each segment is subject to FFT to generate a series of signal coefficient matrices. The channel coefficient matrices and signal coefficient matrices are then multiplied and subjected to inverse-FFT to output a signal representing the received affected radio signal. A variety of channel scattering functions can be used to characterize the response of a transmitter-receiver system to such atmospheric effects.

  5. Aram Dorsum, Candidate ExoMars Rover Landing Site: a Noachian Inverted Fluvial Channel System in Arabia Terra Mars

    NASA Astrophysics Data System (ADS)

    Balme, Matthew; Grindrod, Peter; Sefton-Nash, Elliot; Davis, Joel; Gupta, Sanjeev; Fawdon, Peter

    2016-04-01

    Much of Mars' Noachian-aged southern highlands is dissected by systems of fluvial channels and valleys > 3.7 Ga in age. Arabia Terra, lying between the southern highlands and the northern lowlands, is similarly ancient, yet apparently has few valley networks. This regional lack of valley networks only matches Noachian precipitation predictions from climate models if the Noachian climate was dry and cold [1]. In this scenario, highlands dissection was caused by transient flows of meltwater from large, regionally restricted ice-bodies. However, new results [2,3] show that Arabia Terra is not as poorly dissected as previously thought, and in fact there are extensive networks of inverted channel systems. Here, we describe an example of such a system - Aram Dorsum - which has been studied extensively as an ExoMars Rover candidate landing site. Aram Dorsum is an ~100 km long, 1-2 km wide, branching, flat-topped ridge system, in western Arabia Terra. We have mapped the system using CTX images, DEMs and other data. We interpret the ridge system to be fluvial in origin, preserved in positive relief due to infill and differential erosion; this working hypothesis is used as a conceptual framework for the study. Aram Dorsum is a branching, multi-level, contributory network, set in surrounding floodplains-like material. This demonstrates that it was a relatively long-lived, aggradational fluvial system, rather than an erosional outflow or bedrock-carved fluvial channel. Interestingly, the system shows little evidence for unconfined lateral channel migration, so there must have been significant bank stability. Aram Dorsum was therefore probably once a sizable river and, as just one example of many similar systems, is an exemplar for the middle part of a regional sediment transport system that could have extended from the southern highlands to the northern lowlands. Like Aram Dorsum, many of these other recently-recognized fluvial systems have an origin more consistent with

  6. Jamming in Vertical Channels

    NASA Astrophysics Data System (ADS)

    Baxter, G. William; Steel, Fiona

    2011-03-01

    We study jamming of low aspect-ratio cylindrical Delrin grains in a vertical channel. Grain heights are less than their diameter so the grains resemble antacid tablets, coins, or poker chips. These grains are allowed to fall through a vertical channel with a square cross section where the channel width is greater than the diameter of a grain and constant throughout the length of the channel with no obstructions or constrictions. Grains are sometimes observed to form jams, stable structures supported by the channel walls with no support beneath them. The probability of jam occurrence and the strength or robustness of a jam is effected by grain and channel sizes. We will present experimental measurements of the jamming probability and jam strength in this system and discuss the relationship of these results to other experiments and theories. Supported by an Undergraduate Research Grant from Penn State Erie, The Behrend College.

  7. Cocaine sensitization increases Ih current channel subunit 2 (HCN2) protein expression in structures of the Mesocorticolimbic System

    PubMed Central

    Santos-Vera, Bermary; Vázquez-Torres, Rafael; García Marrero, Hermes G.; Ramos Acevedo, Juan M.; Arencibia-Albite, Francisco; Vélez-Hernández, María E.; Miranda, Jorge D.; Jiménez-Rivera, Carlos A.

    2013-01-01

    Alteration of the biological activity among neuronal components of the Mesocorticolimbic (MCL) system has been implicated in the pathophysiology of drug abuse. Changes in the electrophysiological properties of neurons involved in the reward circuit seem to be of utmost importance in addiction. The Hyperpolarization-Activated Cyclic-Nucleotide Current, Ih, is a prominent mixed cation current present in neurons. The biophysical properties of the Ih and its potential modulatory role in cell excitability depend on the expression profile of the Hyperpolarization-activated cyclic nucleotide gated channel (HCN) subunits. We investigated whether cocaine-induced behavioral sensitization, an animal model of drug addiction, elicits region-specific changes in the expression of the HCN2 channel’s subunit in the MCL system. Tissue samples from the ventral tegmental area, prefrontal cortex, nucleus accumbens and hippocampus were analyzed using Western Blot. Our findings demonstrate that cocaine treatment induced a significant increase in the expression profile of the HCN2 subunit in both, its glycosylated and non-glycosylated protein isoforms, in all areas tested. The increase in the glycosylated isoform was only observed in the ventral tegmental area. Together, these data suggest that the observed changes in MCL excitability during cocaine addiction might be associated to alterations in the subunit composition of their HCN channels. PMID:23203153

  8. TRP Channels

    PubMed Central

    Venkatachalam, Kartik; Montell, Craig

    2011-01-01

    The TRP (Transient Receptor Potential) superfamily of cation channels is remarkable in that it displays greater diversity in activation mechanisms and selectivities than any other group of ion channels. The domain organizations of some TRP proteins are also unusual, as they consist of linked channel and enzyme domains. A unifying theme in this group is that TRP proteins play critical roles in sensory physiology, which include contributions to vision, taste, olfaction, hearing, touch, and thermo- and osmosensation. In addition, TRP channels enable individual cells to sense changes in their local environment. Many TRP channels are activated by a variety of different stimuli and function as signal integrators. The TRP superfamily is divided into seven subfamilies: the five group 1 TRPs (TRPC, TRPV, TRPM, TRPN, and TRPA) and two group 2 subfamilies (TRPP and TRPML). TRP channels are important for human health as mutations in at least four TRP channels underlie disease. PMID:17579562

  9. Channel formation in Pb-Sn, Pb-Sb, and Pb-Sn-Sb alloy ingots and comparison with the system NH4Cl-H2O

    NASA Technical Reports Server (NTRS)

    Hellawell, A.; Sarazin, J. R.

    1988-01-01

    The formation of segregation channels during the unidirectional solidification of base chilled ingots has been studied as a function of composition in binary Pb-Sn and Pb-Sb and ternary Pb-Sn-Sb alloys. The patterns of channel distribution were characterized in the binary and ternary systems and are described as functions of temperature gradients, growth rates, dendrite spacings, and interdendritic permeabilities. Channels appear to nucleate at random across a dendritic front and subsequently to interact as they propagate, decreasing in density across the front. Assuming that the interdendritic spacing is the characteristic distance for a liquid perturbation, yields critical effective Rayleigh numbers which lie within a factor of x 40 for both metallic and aqueous systems. This correlation is close, considering the sensitivity to any assumed dimension and the range of material properties involved, and is taken to support a model for channel nucleation occurring close to the dendritic growth front.

  10. Development of manufacturing systems for nanocrystalline and ultra-fine grain materials employing indexing equal channel angular pressing

    NASA Astrophysics Data System (ADS)

    Hester, Michael Wayne

    Nanotechnology offers significant opportunities in providing solutions to existing engineering problems as well as breakthroughs in new fields of science and technology. In order to fully realize benefits from such initiatives, nanomanufacturing methods must be developed to integrate enabling constructs into commercial mainstream. Even though significant advances have been made, widespread industrialization in many areas remains limited. Manufacturing methods, therefore, must continually be developed to bridge gaps between nanoscience discovery and commercialization. A promising technology for integration of top-down nanomanufacturing yet to receive full industrialization is equal channel angular pressing, a process transforming metallic materials into nanostructured or ultra-fine grained materials with significantly improved performance characteristics. To bridge the gap between process potential and actual manufacturing output, a prototype top-down nanomanufacturing system identified as indexing equal channel angular pressing (IX-ECAP) was developed. The unit was designed to capitalize on opportunities of transforming spent or scrap engineering elements into key engineering commodities. A manufacturing system was constructed to impose severe plastic deformation via simple shear in an equal channel angular pressing die on 1100 and 4043 aluminum welding rods. 1/4 fraction factorial split-plot experiments assessed significance of five predictors on the response, microhardness, for the 4043 alloy. Predictor variables included temperature, number of passes, pressing speed, back pressure, and vibration. Main effects were studied employing a resolution III design. Multiple linear regression was used for model development. Initial studies were performed using continuous processing followed by contingency designs involving discrete variable length work pieces. IX-ECAP offered a viable solution in severe plastic deformation processing. Discrete variable length work piece

  11. Model Based Prediction of Uplink Multi-Path Fading Channel Response for Pre-Equalization in Mobile MC-CDMA Systems

    NASA Astrophysics Data System (ADS)

    Mkrtchyan, Gagik; Naito, Katsuhiro; Mori, Kazuo; Kobayashi, Hideo

    Multi-carrier code division multiple access (MC-CDMA) has been considered as one of the promising techniques for the next generation of mobile communication systems because of its efficient bandwidth usage, robustness to the multi-path fading and simple channel-sharing scheme. However, MC-CDMA cannot be employed in the uplink communication where the transmitted signal from each user propagates through the different multi-path fading channel, and the received signals are no longer orthogonal at the base station. As a result, bit error rate (BER) performance in the uplink MC-CDMA communication would be strongly degraded due to the occurrence of multi-user interference (MUI). To solve the MUI problem in the uplink MC-CDMA, the pre-equalization method was proposed in which the uplink signal is pre-equalized at the user terminal by using the channel response estimated from the downlink. Although the pre-equalization method is very effective for the stationary uplink channel with fixed users, it is hard to be employed in the time varying fading channel with mobile users, because there is a big difference in the channel responses between downlink and uplink. For the efficient MUI compensation, each user terminal would be required to predict the future channel conditions based on the current observation. This paper proposes a method for model based uplink channel response prediction by employing the spectral decomposition of the downlink channel impulse response. Computer simulation results show that the proposed method can achieve the accurate prediction of channel response for mobile users during the uplink transmission and allows the effective MUI compensation.

  12. Parallel Multistage Decision Feedback Equalizer for Single-Carrier Layered Space-Time Systems in Frequency-Selective Channels

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Wang, Haifeng; Cheng, Shixin; Chen, Ming

    2004-12-01

    Space-time transmission techniques can greatly increase the spectral efficiency. In this paper, a parallel multistage decision feedback equalizer (PMDFE) is proposed for single-carrier layered space-time systems with a fixed cyclic prefix over frequency-selective channels. It is composed of a parallel interference canceller, a multiple-input single-output decision feedback equalizer (MISO-DFE), and a linear combiner. The soft output of the MISO-DFE is linearly combined with the previous tentative soft decision. In addition, an algorithm is proposed to obtain tentative soft and hard decisions for initializing the equalizer. The initializing complexity of the PMDFE is lower than that of MIMO-OFDM. Simulation results show that the PMDFE outperforms MIMO-OFDM and previously existing equalizers for single-carrier layered space-time systems.

  13. Ancient drainage basin of the Tharsis region, Mars: Potential source for outflow channel systems and putative oceans or paleolakes

    USGS Publications Warehouse

    Dohm, J.M.; Ferris, J.C.; Baker, V.R.; Anderson, R.C.; Hare, T.M.; Strom, R.G.; Barlow, N.G.; Tanaka, K.L.; Klemaszewski, J.E.; Scott, D.H.

    2001-01-01

    Paleotopographic reconstructions based on a synthesis of published geologic information and high-resolution topography, including topographic profiles, reveal the potential existence of an enormous drainage basin/aquifer system in the eastern part of the Tharsis region during the Noachian Period. Large topographic highs formed the margin of the gigantic drainage basin. Subsequently, lavas, sediments, and volatiles partly infilled the basin, resulting in an enormous and productive regional aquifer. The stacked sequences of water-bearing strata were then deformed locally and, in places, exposed by magmatic-driven uplifts, tectonic deformation, and erosion. This basin model provides a potential source of water necessary to carve the large outflow channel systems of the Tharsis and surrounding regions and to contribute to the formation of putative northern-plains ocean(s) and/or paleolakes. Copyright 2001 by the American Geophysical Union.

  14. Saga of renin-angiotensin system and calcium channels in hypertensive diabetics: does it have a therapeutic edge?

    PubMed

    Kumar, Arun H S; Ramarao, P

    2005-01-01

    Current understanding of the genesis of diabetic vascular disease suggests that vascular complications, such as atherosclerosis and hypertension, are associated with changes in structural and functional parameters. Experimental and epidemiological data suggest that activation of the renin-angiotensin-aldosterone system plays an important role in the development of micro- and macro-vascular complications. Most of the negative cardiovascular actions of angiotensin II are mediated through AT1 receptors, whereas the AT2 receptors mediate largely beneficial effects. Hence, compared to angiotensin converting enzyme inhibitors (ACEIs), selective AT1 receptor blockers (ARBs) should provide additional end organ protection via AT2 receptors activation. Although ACEIs are useful therapeutically, they are being currently displaced by ARBs. Enhanced calcium ion channel activity is reported in vascular smooth muscles from diabetic animal models. Clinical benefits of calcium channel blockers (CCBs) in diabetic hypertensive patients are controversial, but there is increasing experimental evidence for the beneficial effects of dihydropyridine-type CCBs. Although the treatment of hypertension in diabetics reduces cardiovascular and microvascular complications, the ideal strategy for treating hypertension in diabetics has not been well defined and warrants a combination approach. Only limited clinical data regarding the use of ARBs in combination with CCBs in diabetics are available. The experimental data suggest that combination of a CCB and an AT1 receptor blocker, or a hypothetical dual blocker of AT1 receptors as well as of calcium channels would be an ideal regimen. There is, however, no conclusive clinical evidence to support the combined use of these drugs. This review highlights the available experimental data that support the therapeutic benefits of this combination. PMID:16007228

  15. Athermalized channeled spectropolarimeter enhancement.

    SciTech Connect

    Jones, Julia Craven; Way, Brandyn Michael; Mercier, Jeffrey Alan; Hunt, Jeffery P.

    2013-09-01

    Channeled spectropolarimetry can measure the complete polarization state of light as a function of wavelength. Typically, a channeled spectropolarimeter uses high order retarders made of uniaxial crystal to amplitude modulate the measured spectrum with the spectrally-dependent Stokes polarization information. A primary limitation of conventional channeled spectropolarimeters is related to the thermal variability of the retarders. Thermal variation often forces frequent system recalibration, particularly for field deployed systems. However, implementing thermally stable retarders, made of biaxial crystal, results in an athermal channeled spectropolarimeter that relieves the need for frequent recalibration. This report presents experimental results for an anthermalized channeled spectropolarimeter prototype produced using potassium titanyl phosphate. The results of this prototype are compared to the current thermal stabilization state of the art. Finally, the application of the technique to the thermal infrared is studied, and the athermalization concept is applied to an infrared imaging spectropolarimeter design.

  16. An Inductively Powered Scalable 32-Channel Wireless Neural Recording System-on-a-Chip for Neuroscience Applications

    PubMed Central

    Lee, Seung Bae; Lee, Hyung-Min; Kiani, Mehdi; Jow, Uei-Ming; Ghovanloo, Maysam

    2014-01-01

    We present an inductively powered 32-channel wireless integrated neural recording (WINeR) system-on-a-chip (SoC) to be ultimately used for one or more small freely behaving animals. The inductive powering is intended to relieve the animals from carrying bulky batteries used in other wireless systems, and enables long recording sessions. The WINeR system uses time-division multiplexing along with a novel power scheduling method that reduces the current in unused low-noise amplifiers (LNAs) to cut the total SoC power consumption. In addition, an on-chip high-efficiency active rectifier with optimized coils help improve the overall system power efficiency, which is controlled in a closed loop to supply stable power to the WINeR regardless of the coil displacements. The WINeR SoC has been implemented in a 0.5-µm standard complementary metal–oxide semiconductor process, measuring 4.9 × 3.3 mm2 and consuming 5.85 mW at ± 1.5 V when 12 out of 32 LNAs are active at any time by power scheduling. Measured input-referred noise for the entire system, including the receiver located at 1.2 m, is 4.95 µVrms in the 1 Hz~10 kHz range when the system is inductively powered with 7-cm separation between aligned coils. PMID:23850753

  17. Performance improvement of FSO/CDMA systems over dispersive turbulence channel using multi-wavelength PPM signaling.

    PubMed

    Dang, Ngoc T; Pham, Anh T

    2012-11-19

    Previous studies show that, compared to on-off keying (OOK) signaling, pulse-position modulation (PPM) is favorable in FSO/CDMA systems thanks to its energy efficiency and simple detection. Nevertheless, when the system bit rate increases and the transmission distance is far, the FSO/CDMA systems using PPM signaling critically suffer from the impact of pulse broadening caused by dispersion, especially when the modulation level is high. In this paper, we therefore propose to use multi-wavelength PPM (MWPPM) signaling to overcome the limitation of PPM. To further improve the system performance, avalanche photodiode (APD) is also used. The performance of the proposed system is theoretically analyzed using a realistic model of Gaussian pulse propagation. To model the impact of intensity fluctuation caused by the atmospheric turbulence, the log-normal channel is used. We find that, by using MWPPM, the effects of both intensity fluctuation and pulse broadening are mitigated, the BER is therefore significantly improved. Additionally, we quantitatively show that the system performance is further improved by using APD, especially when the average APD gain is chosen properly. PMID:23187533

  18. Performance of single and dual-polarized optically preamplified M-ary PPM systems with finite extinction ratios over FSO fading channels

    NASA Astrophysics Data System (ADS)

    Landolsi, Taha; Elrefaie, Aly F.

    2016-05-01

    M-ary pulse position modulation (PPM) systems have been considered in free-space optical (FSO) communications, optical fiber links, and passive optical networks. In this paper, we study the error performance of direct-detection optically preamplified M-ary PPM systems over slowly fading FSO channels. The study considers the combined effects on the probability of bit error, Pb, of channel fading with a given scintillation index, σp2, the transmitter finite extinction ratio, r, and the preamplifier spontaneous emission (ASE) noise. We provide results for both single and dual-polarized systems with symbol sizes M ∈ { 2, 4, …, 1024 } at Pb =10-4 and Pb =10-9. The fading models considered in this study are the exponential, log-normal, and gamma-gamma channels. For single-polarized systems with infinite extinction ratios, we provide closed-form expressions for the bit error probabilities for the three channel models. For the dual-polarized systems we compute them numerically. The results indicate that gamma-gamma fading imposes a more severe penalty than the log-normal case. In this study, the power penalty at Pb =10-9 ranges between 1.8 and 14 dB for the log-normal channel, whereas it ranges between 2.2 and 30.7 dB for the gamma-gamma channel. The study also demonstrates that the power penalty due to the combined effects of transmitter finite r and channel fading is the sum of the penalty due to fading alone and the penalty due to a finite r alone, and that the power penalty for dual-polarized systems is about 0.4 dB larger than single-polarized ones.

  19. Systemic Administration of the TRPV3 Ion Channel Agonist Carvacrol Induces Hypothermia in Conscious Rodents

    PubMed Central

    Feketa, Viktor V.; Marrelli, Sean P.

    2015-01-01

    Therapeutic hypothermia is a promising new strategy for neuroprotection. However, the methods for safe and effective hypothermia induction in conscious patients are lacking. The current study explored the Transient Receptor Potential Vanilloid 3 (TRPV3) channel activation by the agonist carvacrol as a potential hypothermic strategy. It was found that carvacrol lowers core temperature after intraperitoneal and intravenous administration in mice and rats. However, the hypothermic effect at safe doses was modest, while higher intravenous doses of carvacrol induced a pronounced drop in blood pressure and substantial toxicity. Experiments on the mechanism of the hypothermic effect in mice revealed that it was associated with a decrease in whole-body heat generation, but not with a change in cold-seeking behaviors. In addition, the hypothermic effect was lost at cold ambient temperature. Our findings suggest that although TRPV3 agonism induces hypothermia in rodents, it may have a limited potential as a novel pharmacological method for induction of hypothermia in conscious patients due to suboptimal effectiveness and high toxicity. PMID:26528923

  20. Simulation of supercritical flows in rocket-motor engines: application to cooling channel and injection system

    NASA Astrophysics Data System (ADS)

    Ribert, G.; Taieb, D.; Petit, X.; Lartigue, G.; Domingo, P.

    2013-03-01

    To address physical modeling of supercritical multicomponent fluid flows, ideal-gas law must be changed to real-gas equation of state (EoS), thermodynamic and transport properties have to incorporate dense fluid corrections, and turbulence modeling has to be reconsidered compared to classical approaches. Real-gas thermodynamic is presently investigated with validation by NIST (National Institute of Standards and Technology) data. Two major issues of Liquid Rocket Engines (LRE) are also presented. The first one is the supercritical fluid flow inside small cooling channels. In a context of LRE, a strong heat flux coming from the combustion chamber (locally Φ ≈ 80 MW/m2) may lead to very steep density gradients close to the wall. These gradients have to be thermodynamically and numerically captured to properly reproduce in the simulation the mechanism of heat transfer from the wall to the fluid. This is done with a shock-capturing weighted essentially nonoscillatory (WENO) numerical discretization scheme. The second issue is a supercritical fluid injection following experimental conditions [1] in which a trans- or supercritical nitrogen is injected into warm nitrogen. The two-dimensional results show vortex structures with high fluid density detaching from the main jet and persisting in the low-speed region with low fluid density.

  1. From the channel model of an InSb-based superresolution optical disc system to impulse response and resolution limits.

    PubMed

    Hepper, Dietmar

    2011-06-10

    The signal model of a superresolution optical channel can be an efficient tool for developing components of an associated high-density optical disc system. While the behavior of the laser diode, aperture, lens, and detector are properly described, a general mathematical model of the superresolution disc itself has not yet been available until recently. Different approaches have been made to describe the properties of a mask layer, mainly based on temperature- or power-dependent nonlinear effects. A complete signal-based or phenomenological optical channel model--from non-return-to-zero inverted input to disc readout signal--has recently been developed including the reflectivity of a superresolution disc with InSb used for the mask layer. In this contribution, the model is now extended and applied to a moving disc including a land-and-pit structure, and results are compared with data read from real superresolution discs. Both impulse response and resolution limits are derived and discussed. Thus the model provides a bridge from physical to readout signal properties, which count after all. The presented approach allows judging of the suitability of a mask layer material for storage density enhancement already based on static experiments, i.e., even before developing an associated disc drive. PMID:21673750

  2. Multi-channel purge and trap system coupled with ion chromatography for the determination of alkylamines in cosmetics.

    PubMed

    Zhong, Zhixiong; Li, Gongke; Luo, Zhibin; Zhu, Binghui

    2012-02-17

    A new multi-channel purge and trap system coupled with ion chromatography for the determination of six alkylamines in cosmetics was developed. The proposed method, based on purge and trap of the volatile alkylamines, involved in a miniaturization and multi-channel integration of classical steam distillation and a simple approach for routine labs. The procedure was rapidly achieved within 10 min and the matrix interferences could be effectively eliminated. Sample pretreatment frequency was higher than 40 h(-1). The linear ranges were 0.1-15 mg L(-1) and the detection limits varied from 0.023 to 0.038 mg L(-1). This method was successfully utilized to determine the amounts of alkylamines in cosmetics with recoveries ranging from 80.3 to 105.5% and the relative standard deviations (RSDs) ranging from 0.78 to 7.5%. It was proved to be accurate, time-saving, and suitable for the determination of large numbers of cosmetics in a short time. PMID:22244166

  3. Structural controls on the development of submarine channel/fan systems since the Pleistocene in the accretionary wedge off SW Taiwan

    NASA Astrophysics Data System (ADS)

    Shen, Kang-Nien; Tien-Shun Lin, Andrew; Lin, Che-Chuan; Liu, Char-Shine; Wang, Yunshuen

    2016-04-01

    The accretionary wedge off SW Taiwan is the result of incipient arc-continent collision between the Luzon volcanic arc and the northern rifted margin of the South China Sea (SCS). Dynamic interactions of thrusting, folding and a rigorous sediment supply from the Taiwan mountain belts have resulted in two arrays of canyons/channels and slope-fan systems in the accretionary wedge. The Penghu canyon/fan system lies in the lower wedge and near the northern rifted margin of the SCS. The Penghu canyon is a river-fed canyon and receives sediments from southern Taiwan and SE China during eustatic lowstands. It becomes detached from river inputs during eustatic highstands as it is in the present-day. The Gaoping canyon/fan system in the south traverses both the upper slope and lower slope domains of the accretionary wedge. This system is a river-fed system during a full eustatic cycle and it drains sediments from the onshore Gaoping River. We interpreted multiple grids of multichannel seismic reflection data of MCS994, MCS1000-6, MCS1014, MCS1046 collected onboard Ocean Research I during 2012 April to 2013 August to map out thrust/fold structures and channel/fan systems in the study area. Seismic facies analyses were performed on seismic sections and key stratal surfaces of base of Pliocene and base of Pleistocene are correlated from boreholes drilled in the shelf of the northern SCS margin. Our results show that the upper Gaoping Canyon has been confined by structural ridges with limited switching of canyon courses, whereas the lower Gaoping canyon/fan system has been developed on lower slope with channel/levee deposition in multiple slope fans since early Pleistocene. Pleistocene lateral aggrading channel-and-levee systems are especially evident near the modern canyon course in the lower slope. The Penghu can/fan system in the lower accretionary wedge is also evident by seismic facies showing channel cut-and-fill, channel abandonment and channel-and-levee systems. This

  4. SEMICONDUCTOR INTEGRATED CIRCUITS: A four-channel microelectronic system for neural signal regeneration

    NASA Astrophysics Data System (ADS)

    Shushan, Xie; Zhigong, Wang; Xiaoying, Lü; Wenyuan, Li; Haixian, Pan

    2009-12-01

    This paper presents a microelectronic system which is capable of making a signal record and functional electric stimulation of an injured spinal cord. As a requirement of implantable engineering for the regeneration microelectronic system, the system is of low noise, low power, small size and high performance. A front-end circuit and two high performance OPAs (operational amplifiers) have been designed for the system with different functions, and the two OPAs are a low-noise low-power two-stage OPA and a constant-gm RTR input and output OPA. The system has been realized in CSMC 0.5-μm CMOS technology. The test results show that the system satisfies the demands of neuron signal regeneration.

  5. Implementation of a channelized Hotelling observer model to assess image quality of x-ray angiography systems

    PubMed Central

    Favazza, Christopher P.; Fetterly, Kenneth A.; Hangiandreou, Nicholas J.; Leng, Shuai; Schueler, Beth A.

    2015-01-01

    Abstract. Evaluation of flat-panel angiography equipment through conventional image quality metrics is limited by the scope of standard spatial-domain image quality metric(s), such as contrast-to-noise ratio and spatial resolution, or by restricted access to appropriate data to calculate Fourier domain measurements, such as modulation transfer function, noise power spectrum, and detective quantum efficiency. Observer models have been shown capable of overcoming these limitations and are able to comprehensively evaluate medical-imaging systems. We present a spatial domain-based channelized Hotelling observer model to calculate the detectability index (DI) of our different sized disks and compare the performance of different imaging conditions and angiography systems. When appropriate, changes in DIs were compared to expectations based on the classical Rose model of signal detection to assess linearity of the model with quantum signal-to-noise ratio (SNR) theory. For these experiments, the estimated uncertainty of the DIs was less than 3%, allowing for precise comparison of imaging systems or conditions. For most experimental variables, DI changes were linear with expectations based on quantum SNR theory. DIs calculated for the smallest objects demonstrated nonlinearity with quantum SNR theory due to system blur. Two angiography systems with different detector element sizes were shown to perform similarly across the majority of the detection tasks. PMID:26158086

  6. Ultrasonic Digital Communication System for a Steel Wall Multipath Channel: Methods and Results

    SciTech Connect

    TL Murphy

    2006-02-16

    As of the development of this thesis, no commercially available products have been identified for the digital communication of instrumented data across a thick ({approx} 6 n.) steel wall using ultrasound. The specific goal of the current research is to investigate the application of methods for digital communication of instrumented data (i.e., temperature, voltage, etc.) across the wall of a steel pressure vessel. The acoustic transmission of data using ultrasonic transducers prevents the need to breach the wall of such a pressure vessel which could ultimately affect its safety or lifespan, or void the homogeneity of an experiment under test. Actual digital communication paradigms are introduced and implemented for the successful dissemination of data across such a wall utilizing solely an acoustic ultrasonic link. The first, dubbed the ''single-hop'' configuration, can communicate bursts of digital data one-way across the wall using the Differential Binary Phase-Shift Keying (DBPSK) modulation technique as fast as 500 bps. The second, dubbed the ''double-hop'' configuration, transmits a carrier into the vessel, modulates it, and retransmits it externally. Using a pulsed carrier with Pulse Amplitude Modulation (PAM), this technique can communicate digital data as fast as 500 bps. Using a CW carrier, Least Mean-Squared (LMS) adaptive interference suppression, and DBPSK, this method can communicate data as fast as 5 kbps. A third technique, dubbed the ''reflected-power'' configuration, communicates digital data by modulating a pulsed carrier by varying the acoustic impedance at the internal transducer-wall interface. The paradigms of the latter two configurations are believed to be unique. All modulation methods are based on the premise that the wall cannot be breached in any way and can therefore be viably implemented with power delivered wirelessly through the acoustic channel using ultrasound. Methods, results, and considerations for future research are discussed

  7. ETV Report: Siemens Model V-40R-A150 Open Channel UV System

    EPA Science Inventory

    Verification testing of the Siemens Barrier Sunlight V-40R-A150 UV System was completed at the UV Validation and Research Center of New York (UV Center), located in Johnstown, NY. The V-40R System supplied by Siemens utilizes 40 high-output, low-pressure amalgam lamps, oriented ...

  8. ETV Report:Siemens Model H-4XE-HO Open Channel UV System

    EPA Science Inventory

    Verification testing of the Siemens Barrier Sunligt H-4XE-HO UV System was completed at the UV Validation and Research Center of New York (UV Center), located in Johnstown, NY. The H-4XE System utilizes 16 high-output, low-pressure lamps oriented horizontally and parallel to the...

  9. Error probabilities in optical data transmission systems with an atmospheric channel and pointing inaccuracies

    NASA Astrophysics Data System (ADS)

    Mal'Tsev, G. N.

    1991-11-01

    A study is made of the combined effect of atmospheric distortions and antenna pointing errors on the noise immunity of optical data transmission systems with direct detection. The possibility of compensating for the effect of perturbations by increasing the power potential of the system is analyzed. The relative importance of atmospheric distortions and pointing errors is estimated.

  10. Dual-channel telemetry system for recording vocalization-correlated neuronal activity in freely moving squirrel monkeys.

    PubMed

    Grohrock, P; Häusler, U; Jürgens, U

    1997-09-01

    A miniature telemetric system is described which allows simultaneous measurements of neural activity and vocalization in freely moving monkeys within their social group. Single and multi-unit activities were detected with medium impedance electrodes that were fixed to self-made microdrives allowing accurate vertical positioning over a range of 8 mm. Vocalizations were registered by means of a piezo-ceramic device sensing the vocalization-induced skull vibrations. This allowed identification of the vocalizing animal in a larger group and eliminated environmental noise. Neuronal activity and vocalization were transmitted via separate channels of a FM transmitter using different carrier frequencies. The signals were decoded in two conventional FM receivers equipped with an automatic frequency control. The signals were stored for off-line analysis on a HiFi videotape recorder. PMID:9334933

  11. Detection of zonal flow spectra in DIII-D by a dual-channel Doppler backscattering system

    SciTech Connect

    Schmitz, L.; Wang, G.; Hillesheim, J. C.; Rhodes, T. L.; Peebles, W. A.; White, A. E.; Zeng, L.; Carter, T. A.; Solomon, W.

    2008-10-15

    Doppler backscattering (DBS) has been successfully used to measure the ExB flow velocity and local intermediate wavenumber density fluctuation levels in the DIII-D tokamak. Depending on the launch angle and the frequency of the probing beam, the signal backscattered from the plasma cut-off layer is sensitive to density fluctuations at a specific perpendicular wavenumber (1{<=}k{sub perpendicular}{rho}{sub s}{<=}4). Due to the localization and high time resolution for poloidal flow measurements, DBS is well suited to detect stationary and time-dependent shear flows [zonal flows (ZFs)]. We present a novel scheme to measure ZF spectra using a dual-channel DBS system capable of simultaneously probing two minor radii separated by a distance of 0.2 cm<{delta}r<3 cm. Frequency spectra of geodesic acoustic modes and low frequency ZFs (f{<=}10 kHz) have been obtained for 0.6

  12. Development and characterization of 16-channel silicon photomultiplier prototype with sub-mm pixels for high-resolution PET system

    NASA Astrophysics Data System (ADS)

    Shimazoe, K.; Lipovec, A.; Takahashi, H.; Wiest, F.; Iskra, P.; Ganka, T.; Kamada, K.

    2014-11-01

    Silicon photomultipliers (SiPMs) are one of the most promising photodetectors for high-resolution PET systems because of their high gain and fast rise time. The resolution of a modern animal PET scanner is now in the sub-mm range; it has also been reported that an individual readout for pixels is necessary in order to achieve the theoretically best resolution. For achieving sub-mm resolution, a detector with pixelated crystals individually coupled to the photodetector is ideal. To this end, a prototype 16-channel SiPM with a pitch of 500μm was designed and fabricated, and its characteristics were studied. Several parameters, such as dark count rate (DCR), gain, crosstalk, and photon detection efficiency (PDE) are characterized in this study. The developed SiPM shows the performance required for future PET detector application.

  13. Development of phytoplankton communities and common off-flavors in a biofloc technology system used to culture channel catfish Ictalurus punctatus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of biofloc technology production systems continues to increase in the aquaculture industry worldwide. Recent research demonstrated that outdoor biofloc systems can be used to produce high yields of channel catfish (Ictalurus punctatus). However, studies have not yet been performed to deter...

  14. Development of phytoplankton communities and common off-flavors in a biofloc technology system used for the culture of channel catfish (Ictalurus punctatus)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of biofloc technology production systems continues to increase in the aquaculture industry worldwide. Recent research demonstrated that outdoor biofloc systems can be used to produce high yields of channel catfish (Ictalurus punctatus). However, studies have not yet been performed to deter...

  15. Interactive computer system for tuning the cochlear 22-channel implant in young children.

    PubMed

    Clarke, G P; Sandford, M D

    1995-09-01

    A computer system has been developed that has a games computer and a vibrotactile device linked into the Cochlear Diagnostic and Programming System. It uses a child's response to a computer game as a way of eliciting initial electrical thresholds and of maintaining attention, so that a large number of thresholds may be measured in a single session. Results have given times of 15 and 35 minutes for initial programming of all 22 electrodes in two 4-year-olds, and the system has been found to be useful in children from 3 years to early teens. PMID:7668618

  16. The Telecom 1 satellite system - Architecture of the common channel signalling network

    NASA Astrophysics Data System (ADS)

    Guenin, J. P.; Benard-Dende, J. C.; Choi, Y.; Hoang-van, A.

    The Telecom 1 satellite system will be the first French public multiservice digital network for large corporate and professional customers, rendering such services as telephony, low speed data transmission, high speed computer communications, and videoconferencing. Two novel features of the system, designated 'part-time leased-line service' and 'broadcast facility', are suitable for the implementation of advanced computer networking applications such as distributed data bases, network job entry systems, and backup or load-sharing among computer centers. Access to Telecom 1 services is by way of about 300 stations throughout Europe, concentrated in France.

  17. Experimental research and comparison of LDPC and RS channel coding in ultraviolet communication systems.

    PubMed

    Wu, Menglong; Han, Dahai; Zhang, Xiang; Zhang, Feng; Zhang, Min; Yue, Guangxin

    2014-03-10

    We have implemented a modified Low-Density Parity-Check (LDPC) codec algorithm in ultraviolet (UV) communication system. Simulations are conducted with measured parameters to evaluate the LDPC-based UV system performance. Moreover, LDPC (960, 480) and RS (18, 10) are implemented and experimented via a non-line-of-sight (NLOS) UV test bed. The experimental results are in agreement with the simulation and suggest that based on the given power and 10(-3)bit error rate (BER), in comparison with an uncoded system, average communication distance increases 32% with RS code, while 78% with LDPC code. PMID:24663882

  18. Space-for-time substitution and the evolution of a submarine canyon-channel system in a passive progradational margin

    NASA Astrophysics Data System (ADS)

    Micallef, Aaron; Ribó, Marta; Canals, Miquel; Puig, Pere; Lastras, Galderic; Tubau, Xavier

    2014-09-01

    Space-for-time substitution is a concept that has been widely applied, but not thoroughly tested, in some fields of geomorphology. The objective of this study is to test whether the concept of space-for-time substitution is valid in reconstructing the evolution of a submarine canyon-channel system in a passive progradational margin. We use multibeam echosounder data and in situ measurements from the south Ebro Margin to analyse the morphology and morphometry of a sequence of submarine valleys ordered in terms of increasing valley thalweg length. The morphological model of submarine valley evolution that we can propose from this analysis is very similar to established models in the literature, which leads us to conclude that time can be substituted by space when reconstructing the evolution of submarine canyon and channel systems in the south Ebro Margin. By extracting morphometric information from the application of the space-for-time substitution model to our data, we identify a series of morphological patterns as a submarine canyon evolves in a passive progradational margin. These include the geometric similarity of canyon planform shape, an increase in canyon draining efficiency and in the influence of flank slope failures, and an evolution towards equilibrium between canyon form and imposed water and sediment load without net erosion or deposition taking place. We also observe that canyon elongation is higher downslope and that the canyon undergoes an early stage of rapid incision similar to the process of "erosion narrowing" reported in terrestrial rivers. We demonstrate that the conclusions of our study are not limited to submarine valleys in the south Ebro Margin but are applicable to other margins around the world.

  19. Impact of organic nutrient load on biomass accumulation, feed channel pressure drop increase and permeate flux decline in membrane systems.

    PubMed

    Bucs, Sz S; Valladares Linares, R; van Loosdrecht, M C M; Kruithof, J C; Vrouwenvelder, J S

    2014-12-15

    The influence of organic nutrient load on biomass accumulation (biofouling) and pressure drop development in membrane filtration systems was investigated. Nutrient load is the product of nutrient concentration and linear flow velocity. Biofouling - excessive growth of microbial biomass in membrane systems - hampers membrane performance. The influence of biodegradable organic nutrient load on biofouling was investigated at varying (i) crossflow velocity, (ii) nutrient concentration, (iii) shear, and (iv) feed spacer thickness. Experimental studies were performed with membrane fouling simulators (MFSs) containing a reverse osmosis (RO) membrane and a 31 mil thick feed spacer, commonly applied in practice in RO and nanofiltration (NF) spiral-wound membrane modules. Numerical modeling studies were done with identical feed spacer geometry differing in thickness (28, 31 and 34 mil). Additionally, experiments were done applying a forward osmosis (FO) membrane with varying spacer thickness (28, 31 and 34 mil), addressing the permeate flux decline and biofilm development. Assessed were the development of feed channel pressure drop (MFS studies), permeate flux (FO studies) and accumulated biomass amount measured by adenosine triphosphate (ATP) and total organic carbon (TOC). Our studies showed that the organic nutrient load determined the accumulated amount of biomass. The same amount of accumulated biomass was found at constant nutrient load irrespective of linear flow velocity, shear, and/or feed spacer thickness. The impact of the same amount of accumulated biomass on feed channel pressure drop and permeate flux was influenced by membrane process design and operational conditions. Reducing the nutrient load by pretreatment slowed-down the biofilm formation. The impact of accumulated biomass on membrane performance was reduced by applying a lower crossflow velocity and/or a thicker and/or a modified geometry feed spacer. The results indicate that cleanings can be delayed

  20. An expert system for the selection of a suitable method for flow measurement in open channels

    NASA Astrophysics Data System (ADS)

    Simonovic, Slobodan P.

    1990-01-01

    The science of stream gaging has evolved through the years, mainly from the experiences and innovations of its practitioners. Stream-gaging procedures are standardized on the national and international level. However, the selection of a suitable method for flow measurement is still a fairly complex process. The knowledge-based system described in the paper is designed to aid the user in the selection process. Two aspects of selection are considered: physical characteristics of the gaging site and available equipment and/or structures at the gaging site. The system has been designed for the potential use in Environment Canada. The paper also discusses the rule-based expert system development tool, VP-Expert. Final conclusion of the research presented in the paper is that the expert system technology may help in the surface flow measurement process. The application seems to be natural, since stream gaging procedures are mainly derived from actual practice and experience.