WorldWideScience

Sample records for current resonant type

  1. Evaluation of Resonant Damping Techniques for Z-Source Current-Type Inverter

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Loh, Poh Chiang; Gajanayake, C.J.;

    2008-01-01

    for damping triggered resonant oscillations. In total, two compensators are needed for wave-shaping the inverter boost factor and modulation ratio, and they can conveniently be implemented using first-in first-out stacks and embedded timers of modern digital signal processors widely used in motion control...

  2. The effect of cavity tuning on oxygen beam currents of an A-ECR type 14 GHz electron cyclotron resonance ion source.

    Science.gov (United States)

    Tarvainen, O; Orpana, J; Kronholm, R; Kalvas, T; Laulainen, J; Koivisto, H; Izotov, I; Skalyga, V; Toivanen, V

    2016-09-01

    The efficiency of the microwave-plasma coupling plays a significant role in the production of highly charged ion beams with electron cyclotron resonance ion sources (ECRISs). The coupling properties are affected by the mechanical design of the ion source plasma chamber and microwave launching system, as well as damping of the microwave electric field by the plasma. Several experiments attempting to optimize the microwave-plasma coupling characteristics by fine-tuning the frequency of the injected microwaves have been conducted with varying degrees of success. The inherent difficulty in interpretation of the frequency tuning results is that the effects of microwave coupling system and the cavity behavior of the plasma chamber cannot be separated. A preferable approach to study the effect of the cavity properties of the plasma chamber on extracted beam currents is to adjust the cavity dimensions. The results of such cavity tuning experiments conducted with the JYFL 14 GHz ECRIS are reported here. The cavity properties were adjusted by inserting a conducting tuner rod axially into the plasma chamber. The extracted beam currents of oxygen charge states O(3+)-O(7+) were recorded at various tuner positions and frequencies in the range of 14.00-14.15 GHz. It was observed that the tuner position affects the beam currents of high charge state ions up to several tens of percent. In particular, it was found that at some tuner position / frequency combinations the plasma exhibited "mode-hopping" between two operating regimes. The results improve the understanding of the role of plasma chamber cavity properties on ECRIS performances.

  3. The effect of cavity tuning on oxygen beam currents of an A-ECR type 14 GHz electron cyclotron resonance ion source

    Science.gov (United States)

    Tarvainen, O.; Orpana, J.; Kronholm, R.; Kalvas, T.; Laulainen, J.; Koivisto, H.; Izotov, I.; Skalyga, V.; Toivanen, V.

    2016-09-01

    The efficiency of the microwave-plasma coupling plays a significant role in the production of highly charged ion beams with electron cyclotron resonance ion sources (ECRISs). The coupling properties are affected by the mechanical design of the ion source plasma chamber and microwave launching system, as well as damping of the microwave electric field by the plasma. Several experiments attempting to optimize the microwave-plasma coupling characteristics by fine-tuning the frequency of the injected microwaves have been conducted with varying degrees of success. The inherent difficulty in interpretation of the frequency tuning results is that the effects of microwave coupling system and the cavity behavior of the plasma chamber cannot be separated. A preferable approach to study the effect of the cavity properties of the plasma chamber on extracted beam currents is to adjust the cavity dimensions. The results of such cavity tuning experiments conducted with the JYFL 14 GHz ECRIS are reported here. The cavity properties were adjusted by inserting a conducting tuner rod axially into the plasma chamber. The extracted beam currents of oxygen charge states O3+-O7+ were recorded at various tuner positions and frequencies in the range of 14.00-14.15 GHz. It was observed that the tuner position affects the beam currents of high charge state ions up to several tens of percent. In particular, it was found that at some tuner position / frequency combinations the plasma exhibited "mode-hopping" between two operating regimes. The results improve the understanding of the role of plasma chamber cavity properties on ECRIS performances.

  4. The effect of cavity tuning on oxygen beam currents of an A-ECR type 14 GHz electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Tarvainen, O., E-mail: olli.tarvainen@jyu.fi; Orpana, J.; Kronholm, R.; Kalvas, T.; Laulainen, J.; Koivisto, H. [Department of Physics (JYFL), University of Jyväskylä, 40500 Jyväskylä (Finland); Izotov, I.; Skalyga, V. [Institute of Applied Physics, RAS, 46 Ul’yanova St., 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod (UNN), 23 Gagarina St., 603950 Nizhny Novgorod (Russian Federation); Toivanen, V. [European Organization for Nuclear Research (CERN), 1211 Geneva 23 (Switzerland)

    2016-09-15

    The efficiency of the microwave-plasma coupling plays a significant role in the production of highly charged ion beams with electron cyclotron resonance ion sources (ECRISs). The coupling properties are affected by the mechanical design of the ion source plasma chamber and microwave launching system, as well as damping of the microwave electric field by the plasma. Several experiments attempting to optimize the microwave-plasma coupling characteristics by fine-tuning the frequency of the injected microwaves have been conducted with varying degrees of success. The inherent difficulty in interpretation of the frequency tuning results is that the effects of microwave coupling system and the cavity behavior of the plasma chamber cannot be separated. A preferable approach to study the effect of the cavity properties of the plasma chamber on extracted beam currents is to adjust the cavity dimensions. The results of such cavity tuning experiments conducted with the JYFL 14 GHz ECRIS are reported here. The cavity properties were adjusted by inserting a conducting tuner rod axially into the plasma chamber. The extracted beam currents of oxygen charge states O{sup 3+}–O{sup 7+} were recorded at various tuner positions and frequencies in the range of 14.00–14.15 GHz. It was observed that the tuner position affects the beam currents of high charge state ions up to several tens of percent. In particular, it was found that at some tuner position / frequency combinations the plasma exhibited “mode-hopping” between two operating regimes. The results improve the understanding of the role of plasma chamber cavity properties on ECRIS performances.

  5. Load characteristics of wireless power transfer system with different resonant types and resonator numbers

    Science.gov (United States)

    Zhang, Yiming; Zhao, Zhengming; Chen, Kainan; Fan, Jun

    2017-05-01

    Wireless Power Transfer (WPT) has been the research focus and applied in many fields. Normally power is transferred wirelessly to charge the battery, which requires specific load characteristics. The load characteristics are essential for the design and operation of the WPT system. This paper investigates the load characteristics of the WPT system with different resonant types and resonator numbers. It is found that in a WPT system with series or LCL resonance under a constant voltage source, the load characteristic is determined by the number of inductors. Even number of inductors results in a constant current characteristic and odd number constant voltage characteristic. Calculations, simulations, and experiments verify the analysis.

  6. Electron cyclotron resonance heating and current drive

    Energy Technology Data Exchange (ETDEWEB)

    Fidone, I.; Castejon, F.

    1992-07-01

    A brief summary of the theory and experiments on electron- cyclotron heating and current drive is presented. The general relativistic formulation of wave propagation and linear absorption is considered in some detail. The O-mode and the X-mode for normal and oblique propagation are investigated and illustrated by several examples. The experimental verification of the theory in T-10 and D- III-D is briefly discussed. Quasilinear evolution of the momentum distribution and related applications as, for instance, non linear wave, damping and current drive, are also considered for special cases of wave frequencies, polarization and propagation. In the concluding section we present the general formulation of the wave damping and current drive in the absence of electron trapping for arbitrary values of the wave frequency. (Author) 13 refs.

  7. Piezoelectric resonators with mechanical damping and resistance in current conduction

    Institute of Scientific and Technical Information of China (English)

    Yook-Kong; YONG; Mihir; S; PATEL

    2007-01-01

    A novel design method for high Q piezoelectric resonators was presented and proposed using the 3-D equations of linear piezoelectricity with quasi-electrostatic approximation which include losses attributed to mechanical damping in solid and resistance in current conduction. There is currently no finite element software for estimating the Q of a resonator without apriori assumptions of the resonator impedance or damping. There is a necessity for better and more realistic modeling of resonators and filters due to miniaturization and the rapid advances in frequency ranges in telecommunication.We presented new three-dimensional finite element models of quartz and barium titanate resonators with mechanical damping and resistance in current conduction. Lee, Liu and Ballato's 3-D equations of linear piezoelectricity with quasi-electro- static approximation which include losses attributed to mechanical damping in solid and resistance in current conduction were formulated in a weak form and implemented in COMSOL. The resulting finite element model could predict the Q and other electrical parameters for any piezoelectric resonator without apriori assumptions of damping or resistance. Forced and free vibration analyses were performed and the results for the Q and other electrical parameters were obtained. Comparisons of the Q and other electrical parameters obtained from the free vibration analysis with their corresponding values from the forced vibration analysis were found to be in excellent agreement. Hence, the frequency spectra obtained from the free vibration analysis could be used for designing high Q resonators. Results for quartz thickness shear AT-cut and SC-cut resonators and thickness stretch poled barium titanate resonators were presented. An unexpected benefit of the model was the prediction of resonator Q with energy losses via the mounting supports.

  8. Tuning Coler Magnetic Current Apparatus with Magneto-Acoustic Resonance

    Science.gov (United States)

    Ludwig, Thorsten

    An attempt was made to tune the Coler magnetic current apparatus with the magneto acoustic resonance of the magnetic rods. Measurements with a replica of the famous Coler "Magnetstromapparat" were conducted. In order to tune the acoustic, magnetic and electric resonance circuits of the Coler device the magneto-acoustic resonance was measured with a frequency scan through a function generator and a lock-in amplifier. The frequency generator was powering a driving coil, while the lock-in was connected to a pickup coil. Both coils were placed on a magnetic rod. Resonances were observed up to the 17th harmonic. The quality Q of the observed resonances was 270. To study the magneto-acoustic resonance in the time domain a pair of Permendur rods were employed. The magneto-acoustic resonances of the Permendur rods were observed with an oscilloscope. Spectra of the magneto acoustic resonance were measured for the Permendur rods and for a Coler replica magnet in the frequency range from 25 kHz to 380 kHz. The next step was to bring the resonances of the Permendur rods close together so that they overlap. The 10thharmonic was chosen because it was close to the 180 kHz that Hans Coler related to ferromagnetism. Further more magneto-acoustic coupling between the Permendur rods was studied. Finally the question was explored if Hans Coler converted vacuum fluctuations via magnetic and acoustic resonance into electricity. There is a strong connection between magnetism and quantum field zero point energy (ZPE). An outlook is given on next steps in the experiments to unveil the working mechanism of the Coler magnetic current apparatus.

  9. Photonic currents in driven and dissipative resonator lattices

    Science.gov (United States)

    Mertz, Thomas; Vasić, Ivana; Hartmann, Michael J.; Hofstetter, Walter

    2016-07-01

    Arrays of coupled photonic cavities driven by external lasers represent a highly controllable setup to explore photonic transport. In this paper we address (quasi)-steady states of this system that exhibit photonic currents introduced by engineering driving and dissipation. We investigate two approaches: in the first one, photonic currents arise as a consequence of a phase difference of applied lasers and, in the second one, photons are injected locally and currents develop as they redistribute over the lattice. Effects of interactions are taken into account within a mean-field framework. In the first approach, we find that the current exhibits a resonant behavior with respect to the driving frequency. Weak interactions shift the resonant frequency toward higher values, while in the strongly interacting regime in our mean-field treatment the effect stems from multiphotonic resonances of a single driven cavity. For the second approach, we show that the overall lattice current can be controlled by incorporating few cavities with stronger dissipation rates into the system. These cavities serve as sinks for photonic currents and their effect is maximal at the onset of quantum Zeno dynamics.

  10. A resonant series counterpulse technique for high current opening switches

    Energy Technology Data Exchange (ETDEWEB)

    Dijk, E. van [Delft Univ. of Technology (Netherlands). Lab. for Power Electronics and Electrical Machines; Gelder, P. van [TNO PML-Pulse Physics Lab., Delft (Netherlands)

    1995-01-01

    A counterpulse technique for the controlled interruption of very high currents in inductive storage pulsed power systems is described and analyzed, and some simulation results of its performance are presented. The accompanying circuit comprises a pre-charged capacitor bank, connected in series with the inductive load, which has to be provided with a current pulse. Upon actuation, a resonant counterpulse current is created in the opening switch, connected in parallel with the current source and the load. In this way, the opening switch is opened at low current. A separate closing switch prevents closing of the opening switch at high voltage. Operation of the opening switch, often a mechanical switch, at low current and low voltage prevents arc erosion of the contacts. The advantage of this circuit compared to other counterpulse circuits is that the capacitor bank does not experience a voltage reversal. Electrolytic capacitors, which have a high energy density, are applied. The remaining energy of the capacitor bank after opening the opening switch, is transferred to the load. The required initial voltage of the capacitor bank is only a few hundred volts, whereas it may be above a kilovolt in other circuits. Another advantage of the method described here is that the load does not experience a pre-current, causing unwanted preheating of the load, before the resonant current is activated. At the moment, work is being performed at the Pulse Physics Laboratory to develop the resonant series counterpulse circuit for use with rail accelerators, which must be supplied with current pulses in the millisecond range up to the mega-ampere level.

  11. Current correlators and form factors in the resonance region

    Energy Technology Data Exchange (ETDEWEB)

    Rosell, I. [Departamento de Ciencias Fisicas, Matematicas y de la Computacion, Universidad CEU Cardenal Herrera, c/Sant Bartomeu 55, E-46115 Alfara del Patriarca, Valencia (Spain); IFIC, Universitat de Valencia - CSIC, Apt. Correus 22085, E-46071 Valencia (Spain)

    2009-01-15

    Within Resonance Chiral Theory and in the context of QCD current correlators at next-to-leading order in 1/N{sub C}, we have analyzed the two-body form factors which include resonances as a final state. The short-distance constraints have been studied. One of the main motivations is the estimation of the chiral low-energy constants at subleading order, that is, keeping full control of the renormalization scale dependence. As an application we show the resonance estimation of some coupling, L{sub 10}{sup r}({mu}{sub 0})=(-4.4{+-}0.9).10{sup -3} and C{sub 87}{sup r}({mu}{sub 0})=(3.1{+-}1.1).10{sup -5}.

  12. Exact temporal eddy current compensation in magnetic resonance imaging systems.

    Science.gov (United States)

    Morich, M A; Lampman, D A; Dannels, W R; Goldie, F D

    1988-01-01

    A step-response method has been developed to extract the properties (amplitudes and decay time constants) of intrinsic-eddy-current-sourced magnetic fields generated in whole-body magnetic resonance imaging systems when pulsed field gradients are applied. Exact compensation for the eddy-current effect is achieved through a polynomial rooting procedure and matrix inversion once the 2 N properties of the N-term decay process are known. The output of the inversion procedure yields the required characteristics of the filter for spectrum magnitude and phase equalization. The method is described for the general case along with experimental results for one-, two-, and three-term inversions. The method's usefulness is demonstrated for the usually difficult case of long-term (200-1000-ms) eddy-current compensation. Field-gradient spectral flatness measurements over 30 mHz-100 Hz are given to validate the method.

  13. Inner Current Loop Analysis and Design Based on Resonant Regulators for Isolated Microgrids

    DEFF Research Database (Denmark)

    Federico, de Bosio; de Sousa Ribeiro, Luiz Antonio; Soares Lima, Marcel

    2015-01-01

    coupling in the design of proportional resonant controllers for these inner loops in voltage source inverters operating in islanded microgrids. It is also shown that the state feedback coupling has an important effect in the performance of the control loops by increasing the steady-state error......Inner current and voltage loops are fundamental in achieving good performance of microgrids based on power electronics voltage source inverters. The analysis and design of these loops are essential for the adequate operation of these systems. This paper investigates the effect of state feedback....... A comparison between different types of proportional+resonant controllers is done. Experimental results verify the theoretical assumptions done....

  14. Multicusp type Electron Cyclotron Resonance ion source for plasma processing

    Energy Technology Data Exchange (ETDEWEB)

    Amemiya, Hiroshi; Shigueoka, Yoshyuki (Institute of Physical and Chemical Research, Wako, Saitama (Japan)); Ishii, Shigeyuki

    1991-02-01

    A multi-cusp type ECR (electron cyclotron resonance) ion source is built with use of SmCo magnets and 2.45 GHz-TE{sub 11} circular mode microwave. The ion source is operated at pressures from 10{sup -4} to 10{sup -3} Torr with the input microwave power from 100 to 400 W. In hydrogen, the current density of H{sup +} is higher than those of H{sub 2}{sup +} and H{sub 3}{sup +}. The dependence of the fraction of each ion species on the power and pressure is measured and explained by rate equations. The source is operated also in other gases. Mass spectra in He, N{sub 2}, O{sub 2}, Ar and CH{sub 4} are shown together with the pressure and power dependences. Multicharged state of up to 3 has been obtained. (author).

  15. Measuring ac losses in superconducting cables using a resonant circuit:Resonant current experiment (RESCUE)

    DEFF Research Database (Denmark)

    Däumling, Manfred; Olsen, Søren Krüger; Rasmussen, Carsten;

    1998-01-01

    be recorded using, for example, a digital oscilloscope. The amplitude decay of the periodic voltage or current accurately reflects the power loss in the system. It consists of two components-an ohmic purely exponential one (from leads, contacts, etc.), and a nonexponential component originating from......A simple way to obtain true ac losses with a resonant circuit containing a superconductor, using the decay of the circuit current, is described. For the measurement a capacitor is short circuited with a superconducting cable. Energy in the circuit is provided by either charging up the capacitors...... with a certain voltage, or letting a de flow in the superconductor. When the oscillations are started-either by opening a switch in case a de is flowing or by closing a switch to connect the charged capacitors with the superconductor-the current (via a Rogowski coil) or the voltage on the capacitor can...

  16. Resonant Strip Line BPM for Ultra Low Current Measurements

    CERN Document Server

    Dehler, M

    2005-01-01

    Proton beams used in proton therapy facilities like PROSCAN have extremely small currents of an order of 1 nA, which create a challenge for a precise beam position measurements due to their extremely low signal level und subsequent bad signal per noise ratios. For suitable power levels with thse currents, pickups need to have a high shunt impedance, something, which is difficult to design for wide band devices. So for a new stripline bpm design, the coupling of the signal outputs to the electrode was deliberately mismatched to create a resonance at the second harmonic of the RF frequency at 150 MHz. The optimum Q-factor to use is given by the coupling between the bpm electrodes leading to to a Q of 100, an overall shunt impedance of 4 kΩ and power output levels of an order of -120 dBm at the design current of 1 nA. A prototype of the devicehas been manufactured, first measurement results will be presented.

  17. Comparison of resonant current regulators for DFIG during grid voltage distortion

    Institute of Scientific and Technical Information of China (English)

    Yi-peng SONG; Heng NIAN

    2013-01-01

    We investigate two different kinds of resonant current regulators for a doubly fed induction generator (DFIG) under distorted grid voltage conditions:proportional integral resonant (PIR) regulator with traditional resonant part and vector propor-tional integral (VPI) regulator with VPI resonant part. Based on the mathematical model of DFIG under distorted grid voltage, the transfer function and frequency response characteristics of the two current regulators are analyzed and compared. The superiority of the VPI current regulator over the PIR regulator is pointed out, and the influence of discretization methods on the performance of the resonant current regulator is studied. All the results are validated by MATLAB simulation and experiments.

  18. Design and Analysis on a Cryogenic Current Amplifier with a Superconducting Microwave Resonator

    CERN Document Server

    Okazaki, Yuma

    2015-01-01

    We propose a new type of cryogenic current amplifiers, in which low-frequency power spectrum of current can be measured through a measurement of microwave response of a superconducting resonant circuit shunted by a series array of Josephson junctions. From numerical analysis on the equivalent circuit, the numerical value of the input-referred current noise of the proposed amplifier is found to be two orders of magnitude lower than the noise floor measured with the conventional cryogenic current amplifiers based on high-electron-mobility transistors or superconducting quantum interference devices. Our proposal can open new avenues for investigating low-temperature solid-state devices that require lower noise and wider bandwidth power spectrum measurements of current.

  19. Acute stroke magnetic resonance imaging: current status and future perspective.

    Science.gov (United States)

    Kloska, Stephan P; Wintermark, Max; Engelhorn, Tobias; Fiebach, Jochen B

    2010-03-01

    Cerebral stroke is one of the most frequent causes of permanent disability or death in the western world and a major burden in healthcare system. The major portion is caused by acute ischemia due to cerebral artery occlusion by a clot. The minority of strokes is related to intracerebral hemorrhage or other sources. To limit the permanent disability in ischemic stroke patients resulting from irreversible infarction of ischemic brain tissue, major efforts were made in the last decade. To extend the time window for thrombolysis, which is the only approved therapy, several imaging parameters in computed tomography and magnetic resonance imaging (MRI) have been investigated. However, the current guidelines neglect the fact that the portion of potentially salvageable ischemic tissue (penumbra) is not dependent on the time window but the individual collateral blood flow. Within the last years, the differentiation of infarct core and penumbra with MRI using diffusion-weighted images (DWI) and perfusion imaging (PI) with parameter maps was established. Current trials transform these technical advances to a redefined patient selection based on physiological parameters determined by MRI. This review article presents the current status of MRI for acute stroke imaging. A special focus is the ischemic stroke. In dependence on the pathophysiology of cerebral ischemia, the basic principle and diagnostic value of different MRI sequences are illustrated. MRI techniques for imaging of the main differential diagnoses of ischemic stroke are mentioned. Moreover, perspectives of MRI for imaging-based acute stroke treatment as well as monitoring of restorative stroke therapy from recent trials are discussed.

  20. Acute stroke magnetic resonance imaging: current status and future perspective

    Energy Technology Data Exchange (ETDEWEB)

    Kloska, Stephan P. [University of Erlangen-Nuernberg, Department of Neuroradiology, Erlangen (Germany); University of Muenster, Department of Clinical Radiology, Muenster (Germany); Wintermark, Max [University of Virginia, Department of Radiology, Neuroradiology Division, Charlottesville, VA (United States); Engelhorn, Tobias [University of Erlangen-Nuernberg, Department of Neuroradiology, Erlangen (Germany); Fiebach, Jochen B. [Charite, Universitaetsmedizin Berlin, Campus Benjamin Franklin, Center for Stroke Research Berlin (CSB), Department of Neurology, Berlin (Germany)

    2010-03-15

    Cerebral stroke is one of the most frequent causes of permanent disability or death in the western world and a major burden in healthcare system. The major portion is caused by acute ischemia due to cerebral artery occlusion by a clot. The minority of strokes is related to intracerebral hemorrhage or other sources. To limit the permanent disability in ischemic stroke patients resulting from irreversible infarction of ischemic brain tissue, major efforts were made in the last decade. To extend the time window for thrombolysis, which is the only approved therapy, several imaging parameters in computed tomography and magnetic resonance imaging (MRI) have been investigated. However, the current guidelines neglect the fact that the portion of potentially salvageable ischemic tissue (penumbra) is not dependent on the time window but the individual collateral blood flow. Within the last years, the differentiation of infarct core and penumbra with MRI using diffusion-weighted images (DWI) and perfusion imaging (PI) with parameter maps was established. Current trials transform these technical advances to a redefined patient selection based on physiological parameters determined by MRI. This review article presents the current status of MRI for acute stroke imaging. A special focus is the ischemic stroke. In dependence on the pathophysiology of cerebral ischemia, the basic principle and diagnostic value of different MRI sequences are illustrated. MRI techniques for imaging of the main differential diagnoses of ischemic stroke are mentioned. Moreover, perspectives of MRI for imaging-based acute stroke treatment as well as monitoring of restorative stroke therapy from recent trials are discussed. (orig.)

  1. Linear Resonance Compressor for Stirling-Type Cryocoolers Activated by Piezoelectric Stack-Type Elements

    Science.gov (United States)

    Sobol, S.; Grossman, G.

    2015-12-01

    A novel type of a PZT- based compressor operating at mechanical resonance, suitable for pneumatically-driven Stirling-type cryocoolers was developed theoretically and built practically during this research. A resonance operation at relatively low frequency was achieved by incorporating the piezo ceramics into the moving part, and by reducing the effective piezo stiffness using hydraulic amplification. The detailed concept, analytical model and the test results of the preliminary prototype were reported earlier and presented at ICC17 [2]. A fine agreement between the simulations and experiments spurred development of the current actual compressor designed to drive a miniature Pulse Tube cryocooler, particularly our MTSa model, which operates at 103 Hz and requires an average PV power of 11 W, filling pressure of 40 Bar and a pressure ratio of 1.3. The paper concentrates on design aspects and optimization of the governing parameters. The small stroke to diameter ratio (about 1:10) allows for the use of a composite diaphragm instead of a clearance-seal piston. The motivation is to create an adequate separation between the working fluid and the buffer gas of the compressor, thus preventing possible contamination in the cryocooler. Providing efficiency and power density similar to those of conventional linear compressors, the piezo compressor may serve as a good alternative for cryogenic applications requiring extreme reliability and absence of magnetic field interference.

  2. ON THE RESONANT GENERATION OF WEAKLY NONLINEAR STOKES WAVES IN REGIONS WITH FAST VARYING TOPOGRAPHY AND FREE SURFACE CURRENT

    Institute of Scientific and Technical Information of China (English)

    黄虎; 周锡礽

    2001-01-01

    The effect of nonlinearity on the free surface wave resonated by an incident flow over rippled beds, which consist of fast varying topography superimposed on an otherwise slowly varying mean depth, is studied using a WKBJ-type perturbation approach. Synchronous, superharmonic and in particular subharmonic resonance were selectively excited over the fast varying topography with corresponding wavelengths. For a steady current the dynamical system is autonomous and the possible nonlinear steady states and their stability were investigated. When the current has a small oscillatory component the dynamical system becomes non-autonomous, chaos is now possible.

  3. Ferromagnetic-resonance induced electromotive forces in Ni81Fe19 | p-type diamond

    Science.gov (United States)

    Fukui, Naoki; Morishita, Hiroki; Kobayashi, Satoshi; Miwa, Shinji; Mizuochi, Norikazu; Suzuki, Yoshishige

    2016-10-01

    We report on direct-current (DC) electromotive forces (emfs) in a nickel-iron alloy (Ni81 Fe19) | p-type diamond under the ferromagnetic resonance of the Ni81Fe19 layer at room temperature. The observed DC emfs take its maximum around the ferromagnetic resonant frequency of the Ni81Fe19, and their signs are reversed by reversing the direction of an externally-applied magnetic field; it shows that the observed DC emfs are spin-related emfs.

  4. Resonant tunneling and nonlinear current in heterobarrier with complex dispersion of carriers

    CERN Document Server

    Kim, C S; Shtenberg, V B

    2002-01-01

    The study of novel effects in resonant tunneling of electrons in GaAs/Al sub x Ga sub 1 sub - sub x As/GaAs single-barrier structures under an applied electric bias is carried out. GAMMA-X mixing of electron states at the interfaces is responsible for Fano resonance in the barrier transmittance. A motion of Fano resonances and the interaction between Fano and Breit-Wigner resonances in electric field have been investigated. The current-voltage characteristic of the heterobarrier is calculated. It is shown that the differential conductivity presents a way to get the Fano resonance profile and its parameters

  5. Charging of superconducting layers and resonance-related hysteresis in the current-voltage characteristics of coupled Josephson junctions

    Science.gov (United States)

    Shukrinov, Yu. M.; Gaafar, M. A.

    2011-09-01

    A manifestation of a resonance-type hysteresis related to the parametric resonance in the system of coupled Josephson junctions is demonstrated. In contrast with the McCumber and Steward hysteresis, we find that the width of this hysteresis is inversely proportional to the McCumber parameter and it also depends on the coupling between junctions and the boundary conditions. Investigation of the time dependence of the electric charge in superconducting layers allows us to explain the origin of this hysteresis by different charge dynamics for increasing and decreasing bias current processes. The effect of the wavelength of the longitudinal plasma wave created at the resonance on the charging of superconducting layers is demonstrated. We find a strong effect of the dissipation in the system on the amplitude of the charge oscillations at the resonance.

  6. Resonant scattering as a sensitive diagnostic of current collisional plasma models

    Science.gov (United States)

    Ogorzalek, Anna; Zhuravleva, Irina; Allen, Steven W.; Pinto, Ciro; Werner, Norbert; Mantz, Adam; Canning, Rebecca; Fabian, Andrew C.; Kaastra, Jelle S.; de Plaa, Jelle

    2017-08-01

    Resonant scattering is a subtle process that suppresses fluxes of some of the brightest optically thick X-ray emission lines produced by collisional plasmas in galaxy clusters and massive early-type galaxies. The amplitude of the effect depends on the turbulent structure of the hot gas, making it a sensitive velocity probe. It is therefore crucial to properly model this effect in order to correctly interpret high resolution X-ray spectra. Our measurements of resonant scattering with XMM-Newton Reflection Grating Spectrometer in giant elliptical galaxies and with Hitomi in the center of Perseus Cluster show that the potentially rich inference from this effect is limited by the uncertainties in the atomic data underlying plasma codes such as APEC and SPEX. Typically, the effect is of the order of 10-20%, while the discrepancy between the two codes is of similar order or even higher. Precise knowledge of the emissivity and oscillator strengths of lines emitted by Fe XVII and Fe XXV, as well as their respective uncertainties propagated through plasma codes are key to understanding gas dynamics and microphysics in giant galaxies and cluster ICM, respectively. This is especially crucial for massive ellipticals, where sub-eV resolution would be needed to measure line broadening precisely, making resonant scattering an important velocity diagnostic in these systems for the foreseeable future. In this poster, I will summarize current status of resonant scattering measurements and show how they depend on the assumed atomic data. I will also discuss which improvements are essential to maximize scientific inference from future high resolution X-ray spectra.

  7. Current-driven antivortex core resonance measured by the rectifying effect

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Minori, E-mail: mgoto@phys.keio.ac.jp [Graduate School of Engineering Science, Osaka University, J205, 1-3, Machikaneyamacho, Toyonaka, Osaka, 560-8531 (Japan); Nozaki, Yukio, E-mail: nozaki@phys.keio.ac.jp [Department of Physics, Keio University, 22-102, 3-14-1, Hiyoshi, Kohokuku, Yokohama, Kanagawa, 223-8522 (Japan)

    2016-02-15

    We demonstrate the current-driven resonance of a single antivortex core confined in a cross-shaped Ni{sub 81}Fe{sub 19} wire. The antivortex core dynamics can be excited purely by spin transfer torque; therefore, it is significant to understand the current-induced magnetization dynamics. The antivortex core resonance can be measured from the frequency dependence of a rectified voltage generated by an alternating current application. We found that the resonance frequency and peak amplitude greatly depend on the external magnetic field. This result is in good agreement with micromagnetic simulation.

  8. Ultra-thin wideband magnetic-type metamaterial absorber based on LC resonator at low frequencies

    Science.gov (United States)

    Zhang, Linbo; Zhou, Peiheng; Chen, Haiyan; Lu, Haipeng; Xie, Jianliang; Deng, Longjiang

    2015-10-01

    In this paper, we propose to realize a broad absorption band in the frequency regimes of 2-6 GHz based on multiple resonances. A magnetic-type metamaterial absorber with cross-arrow pattern is further demonstrated numerically and experimentally. Two absorption resonances are generated by LC resonance, leading to bandwidth expansion. The equivalent circuit theory and the surface current distributions of the proposed absorber are discussed to analyze the physical mechanism. Moreover, the broad bandwidth can be maintained as incident angle up to 30° for transverse electric polarization and 45° for transverse magnetic polarization. Finally, experimental results show that the proposed absorber with the total thickness of 2.4 mm exhibits a -10 dB absorption bandwidth by more than 70 %. The low-frequency absorber has potential applications in the area of eliminating microwave energy.

  9. Current at a distance and resonant transparency in Weyl semimetals

    Science.gov (United States)

    Stern, Ady; Baum, Yuval; Berg, Erez; Parameswaran, Siddharth

    Surface Fermi arcs are the most prominent manifestation of the topological nature of Weyl semimetals. In the presence of a static magnetic field oriented perpendicular to the sample surface, their existence leads to unique inter-surface cyclotron orbits. We propose two experiments which directly probe the Fermi arcs: a magnetic field dependent non-local DC voltage and sharp resonances in the transmission of electromagnetic waves at frequencies controlled by the field. We show that these experiments are insensitive to small momentum scattering and do not rely on quantum mechanical phase coherence, which renders them far more robust and experimentally accessible than quantum effects. We also comment on the applicability of these ideas to Dirac semimetals.

  10. Scattering-Type Surface-Plasmon-Resonance Biosensors

    Science.gov (United States)

    Wang, Yu; Pain, Bedabrata; Cunningham, Thomas; Seshadri, Suresh

    2005-01-01

    Biosensors of a proposed type would exploit scattering of light by surface plasmon resonance (SPR). Related prior biosensors exploit absorption of light by SPR. Relative to the prior SPR biosensors, the proposed SPR biosensors would offer greater sensitivity in some cases, enough sensitivity to detect bioparticles having dimensions as small as nanometers. A surface plasmon wave can be described as a light-induced collective oscillation in electron density at the interface between a metal and a dielectric. At SPR, most incident photons are either absorbed or scattered at the metal/dielectric interface and, consequently, reflected light is greatly attenuated. The resonance wavelength and angle of incidence depend upon the permittivities of the metal and dielectric. An SPR sensor of the type most widely used heretofore includes a gold film coated with a ligand a substance that binds analyte molecules. The gold film is thin enough to support evanescent-wave coupling through its thickness. The change in the effective index of refraction at the surface, and thus the change in the SPR response, increases with the number of bound analyte molecules. The device is illuminated at a fixed wavelength, and the intensity of light reflected from the gold surface opposite the ligand-coated surface is measured as a function of the angle of incidence. From these measurements, the angle of minimum reflection intensity is determined

  11. Current-voltage characteristic of a resonant tunneling diode under electromagnetic radiation

    National Research Council Canada - National Science Library

    N Hatefi Kargan

    2013-01-01

    In this paper, current-voltage characteristic of a resonant tunneling diode under electromagnetic radiation has been calculated and compared with the results when there is no electromagnetic radiation...

  12. Dual-frequency ferromagnetic resonance to measure spin current coupling in multilayers

    Science.gov (United States)

    Adur, Rohan; Du, Chunhui; Wang, Hailong; Manuilov, Sergei A.; Yang, Fengyuan; Hammel, P. Chris

    2014-08-01

    Spin pumping is a method for injecting a pure spin current into a non-magnetic metal (NM) by inducing precession of a neighboring ferromagnet (FM) at its ferromagnetic resonance frequency. A popular method to detect spin current uses the Inverse Spin Hall Effect (ISHE) to convert the spin current to a detectable charge current and hence a voltage. In order to better understand the role of time independent and high frequency contributions to spin pumping, we sought to detect we attempt to detect spin currents by using a second microwave frequency to detect changes in linewidth of a second ferromagnet due to the spin-torque induced by the spin current from the first ferromagnet. This dual resonance is achieved by pairing a custom broadband coplanar transmission line with the high-Q resonant cavity of a commercial electron paramagnetic resonance spectrometer. This technique is general enough that it should enable the investigation of spin currents in any FM-NM-FM system, for any orientation of external field, and is not sensitive to voltage artifacts often found in ISHE measurements. We find that the condition for simultaneous resonance generates a dc spin current that is too small to produce a measurable change in linewidth of the second ferromagnet, confirming the dominance of ac spin currents in linewidth enhancement measurements.

  13. Fast Reactive Power Sharing, Circulating Current and Resonance Suppression for Parallel Inverters Using Resistive-Capacitive Output Impedance

    DEFF Research Database (Denmark)

    Chen, Yandong; Guerrero, Josep M.; Shuai, Zhikang

    2016-01-01

    virtual impedance loop, the inverter provides fast transient response. Based on the RC-type inverter modeling, the comparative frequency-domain analysis of equivalent output impedances are discussed, and the impact of the virtual complex impedance over the circulating currents and high......In this paper, an inverter using resistivecapacitive output impedance (RC-type inverter) is proposed not only to provide fast reactive power sharing to support microgrid voltage, and but also to reduce circulating currents and damp high-frequency resonances among inverters. Introducing the RC...

  14. Current status of superparamagnetic iron oxide contrast agents for liver magnetic resonance imaging.

    Science.gov (United States)

    Wang, Yi-Xiang J

    2015-12-21

    Five types of superparamagnetic iron oxide (SPIO), i.e. Ferumoxides (Feridex(®) IV, Berlex Laboratories), Ferucarbotran (Resovist(®), Bayer Healthcare), Ferumoxtran-10 (AMI-227 or Code-7227, Combidex(®), AMAG Pharma; Sinerem(®), Guerbet), NC100150 (Clariscan(®), Nycomed,) and (VSOP C184, Ferropharm) have been designed and clinically tested as magnetic resonance contrast agents. However, until now Resovist(®) is current available in only a few countries. The other four agents have been stopped for further development or withdrawn from the market. Another SPIO agent Ferumoxytol (Feraheme(®)) is approved for the treatment of iron deficiency in adult chronic kidney disease patients. Ferumoxytol is comprised of iron oxide particles surrounded by a carbohydrate coat, and it is being explored as a potential imaging approach for evaluating lymph nodes and certain liver tumors.

  15. COMPARISON OF PERFORMANCE PIEZO RESONATORS BAW-TYPE TO CREATE CHEMICAL SENSOR

    Directory of Open Access Journals (Sweden)

    T. A. Kuchmenko

    2014-01-01

    Full Text Available Summary. Currently creation of small inexpensive analytical devices is very actual. Possibility of miniaturization vibrational gas sensors is associated with the possibility of using resonators smaller than the traditionally used sizes. The study used two types of sensors: sensors based on BAW resonators brand RK 169 with frequency of self-oscillation of 10 MHz and a mini - sensors, resonators based on BAW resonators brand MBC 10000 and MBC 15000 with frequencies of self-oscillation of 10 and 15 MHz respectively. As modifier of electrodes polyethylene glycol PEG 2000 was used. Check of sensitivity of microbalance and evaluation other performance properties of sensors was carried in pairs chloroform, 2-propanol and benzene. Mini -sensor has a smaller surface available sorption, whereby mini-sesors have a smaller analytical signal as compared traditional used resonators. Mass of coating which cause failure of self-oscillation for mini -sensors does not exceed 3 mcg and it is much smaller than for traditionally used sensors. It has been established that the analytical signal of mini-sensors in pairs of test compounds is higher than analytical signal of traditionally used sensors. Analytical signal is more for sensors with higher mass of coating and for sensors with higher selfoscillation frequency. The study found that the mini-sensors can be used for a narrow range of problems in the analysis. the sensitivity of mini-sensors is higher than that traditionally used sensors, but they have significant limitations on weight of coating.

  16. Optimized design of resonant controller for stator current harmonic compensation in DFIG wind turbine systems

    DEFF Research Database (Denmark)

    Liu, Changjin; Chen, Wenjie; Blaabjerg, Frede

    2012-01-01

    This paper presents an analytical method to optimize the parameters of resonant controller which is used in a Doubly-Fed Induction Generator (DFIG). In the DFIG control system, the fundamental current loop is controlled by PI-controllers, and the stator harmonic current loop is controlled by reso...... design procedure of the resonant controller parameters is presented. The maximum possible gain of the resonant controller can be directly evaluated from the procedure. Simulations and experiments are presented to validate the complete analysis....... by resonant controllers. The effects of the resonant controller on the system stability and the steady-state performance are discussed in details. The analysis shows that the resonant controller has an important impact on the system stability when the resonant frequency is close to the crossover frequency...... of the open loop gain. The gain of the resonant controller is mainly determined by the DFIG transient inductance, the proportional gain of the PI controller, and the required phase margin. Based on the analytical expression of the phase margin and the crossover frequency of the control system, a systematic...

  17. Theta-frequency resonance in hippocampal CA1 neurons in vitro demonstrated by sinusoidal current injection.

    Science.gov (United States)

    Leung, L S; Yu, H W

    1998-03-01

    Sinusoidal currents of various frequencies were injected into hippocampal CA1 neurons in vitro, and the membrane potential responses were analyzed by cross power spectral analysis. Sinusoidal currents induced a maximal (resonant) response at a theta frequency (3-10 Hz) in slightly depolarized neurons. As predicted by linear systems theory, the resonant frequency was about the same as the natural (spontaneous) oscillation frequency. However, in some cases, the resonant frequency was higher than the spontaneous oscillation frequency, or resonance was found in the absence of spontaneous oscillations. The sharpness of the resonance (Q), measured by the peak frequency divided by the half-peak power bandwidth, increased from a mean of 0.44 at rest to 0.83 during a mean depolarization of 6.5 mV. The phase of the driven oscillations changed most rapidly near the resonant frequency, and it shifted about 90 degrees over the half-peak bandwidth of 8.4 Hz. Similar results were found using a sinusoidal function of slowly changing frequency as the input. Sinusoidal currents of peak-to-peak intensity of >100 pA may evoke nonlinear responses characterized by second and higher harmonics. The theta-frequency resonance in hippocampal neurons in vitro suggests that the same voltage-dependent phenomenon may be important in enhancing a theta-frequency response when hippocampal neurons are driven by medial septal or other inputs in vivo.

  18. Current developments with TRIUMF’s titanium-sapphire laser based resonance ionization laser ion source

    Energy Technology Data Exchange (ETDEWEB)

    Lassen, J., E-mail: LASSEN@triumf.ca; Li, R. [TRIUMF (Canada); Raeder, S. [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Zhao, X.; Dekker, T. [TRIUMF (Canada); Heggen, H. [GSI Helmholtzzentrum für Schwerionenforschung GmbH (Germany); Kunz, P.; Levy, C. D. P.; Mostanmand, M.; Teigelhöfer, A.; Ames, F. [TRIUMF (Canada)

    2017-11-15

    Developments at TRIUMF’s isotope separator and accelerator (ISAC) resonance ionization laser ion source (RILIS) in the past years have concentrated on increased reliability for on-line beam delivery of radioactive isotopes to experiments, as well as increasing the number of elements available through resonance ionization and searching for ionization schemes with improved efficiency. The current status of these developments is given with a list of two step laser ionization schemes implemented recently.

  19. A Drabkin-type spin resonator as tunable neutron beam monochromator

    Energy Technology Data Exchange (ETDEWEB)

    Piegsa, F.M., E-mail: florian.piegsa@phys.ethz.ch [ETH Zürich, Institute for Particle Physics, CH-8093 Zürich (Switzerland); Ries, D. [ETH Zürich, Institute for Particle Physics, CH-8093 Zürich (Switzerland); Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Filges, U.; Hautle, P. [Paul Scherrer Institute, CH-5232 Villigen (Switzerland)

    2015-09-11

    A Drabkin-type spin resonator was designed and successfully implemented at the multi-purpose beam line BOA at the spallation neutron source SINQ at the Paul Scherrer Institute. The device selectively acts on the magnetic moment of neutrons within an adjustable velocity band and hence can be utilized as a tunable neutron beam monochromator. Several neutron time-of-flight (TOF) spectra have been recorded employing various settings in order to characterize its performance. In a first test application the velocity dependent transmission of a beryllium filter was determined. In addition, we demonstrate that using an exponential current distribution in the spin resonator coil the side-maxima in the TOF spectra usually associated with a Drabkin setup can be strongly suppressed.

  20. Self-exited gas oscillations in Helmholtz resonator type combustor

    Science.gov (United States)

    Larionov, V. M.; Saifullin, E. R.; Semenova, E. V.

    2016-01-01

    When the length of the resonance tube is much less and order of the acoustic wavelength is studied. Experimental set-up with a multiport burner is considered. The "energy balance" method is used to calculate the frequency and amplitude of the gas oscillations. The results of measurements and calculations show that increasing the length of the resonance tube causes the excitation oscillation with a first lower frequency. Further, there are no oscillations. When the length of the resonance tube becomes the order of the wavelength, the second resonant frequency is excited. The calculation results are in good agreement with the experimental data.

  1. Sensing Based on Fano-Type Resonance Response of All-Dielectric Metamaterials

    Directory of Open Access Journals (Sweden)

    Elena Semouchkina

    2015-04-01

    Full Text Available A new sensing approach utilizing Mie resonances in metamaterial arrays composed of dielectric resonators is proposed. These arrays were found to exhibit specific, extremely high-Q factor (up to 15,000 resonances at frequencies corresponding to the lower edge of the array second transmission band. The observed resonances possessed with features typical for Fano resonances (FRs, which were initially revealed in atomic processes and recently detected in macro-structures, where they resulted from interference between local resonances and a continuum of background waves. Our studies demonstrate that frequencies and strength of Fano-type resonances in all-dielectric arrays are defined by interaction between local Mie resonances and Fabry-Perot oscillations of Bloch eigenmodes that makes possible controlling the resonance responses by changing array arrangements. The opportunity for obtaining high-Q responses in compact arrays is investigated and promising designs for sensing the dielectric properties of analytes in the ambient are proposed.

  2. Current control loop design and analysis based on resonant regulators for microgrid applications

    DEFF Research Database (Denmark)

    Federico, de Bosio; Pastorelli, Michelle; de Sousa Ribeiro, Luiz Antonio

    2015-01-01

    Voltage and current control loops play an important role in the performance of microgrids employing power electronics voltage source inverters. Correct design of feedback loops is essential for the proper operation of these systems. This paper analyzes the influence of state feedback cross......-coupling in the design of resonant regulators for inner current loops in power converters operating in standalone microgrids. It is also demonstrated that the effect of state feedback cross-coupling degrades the performance of the control loops by increasing the steady-state error. Different resonant regulators...... structures are analyzed and compared, performing experimental tests to validate the results of the theoretical analysis....

  3. Potential of ion cyclotron resonance frequency current drive via fast waves in DEMO

    Science.gov (United States)

    Kazakov, Ye O.; Van Eester, D.; Wauters, T.; Lerche, E.; Ongena, J.

    2015-02-01

    For the continuous operation of future tokamak-reactors like DEMO, non-inductively driven toroidal plasma current is needed. Bootstrap current, due to the pressure gradient, and current driven by auxiliary heating systems are currently considered as the two main options. This paper addresses the current drive (CD) potential of the ion cyclotron resonance frequency (ICRF) heating system in DEMO-like plasmas. Fast wave CD scenarios are evaluated for both the standard midplane launch and an alternative case of exciting the waves from the top of the machine. Optimal ICRF frequencies and parallel wave numbers are identified to maximize the CD efficiency. Limitations of the high frequency ICRF CD operation are discussed. A simplified analytical method to estimate the fast wave CD efficiency is presented, complemented with the discussion of its dependencies on plasma parameters. The calculated CD efficiency for the ICRF system is shown to be similar to those for the negative neutral beam injection and electron cyclotron resonance heating.

  4. Strange Resonance and Charmed Particle Production in Muon-Associated Neutrino Neon Charged-Current Interactions

    Science.gov (United States)

    Hyatt, Eric Roy

    The production of strange resonances and charmed particles in nu_{mu} Ne charged-current interactions was measured in the 15 ft Bubble Chamber. The chamber, filled with a heavy Ne-H_2 mixture, was exposed at Fermilab to a wide-band horn-focussed neutrino beam with peak energy ~20 GeV. In a 390,000 expansion exposure of the chamber, ~125,000 charge-current events occurred within the fiducial volume. Among these events were 4381 (3676) well-reconstructed K _sp{s}{0} ( Lambda^0) decays. The events containing these neutral strange particle decays are examined to measure strange resonance and charmed particle production. Inclusive production rates or rate limits per charged-current event are measured for the K*(890) and Sigma^ {*}(1380) resonances. The production of any particular resonance is measured to be typically {cal O}(1%), and resonance decays are shown to account for 10-25% of K^0 /|{rm K}^0 's and Lambda^0's. Production rates or rate limits are measured for charmed particles via hadronic decays which include a neutral strange particle --these rates are typically {cal O} (1%) and are consistent with the rate at which charmed particle semileptonic decays were observed during the same experiment. ftn*Research supported by the National Science Foundation. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the graduate School of Arts and Sciences, Columbia University.

  5. Second-Order Resonant Interaction of Ring Current Protons with Whistler-Mode Waves

    Institute of Scientific and Technical Information of China (English)

    XIAO Fu-Liang; CHEN Liang-Xu; HE Hui-Yong; ZHOU Qing-Hua

    2008-01-01

    We present a study on the second-order resonant interaction between the ring current protons with Whistler-mode waves propagating near the quasi electrostatic limit following the previous second-order resonant theory.The diffusion coefficients are proportional to the electric field amplitude E,much greater than those for the regular first-order resonance.which are proportional to the electric field amplitudes square E2.Numerical calculations for the pitch angle scattering are performed for typical energies of protons Ek=50ke V and 100ke V at locations L=2 and L=3.5.The timescale for the loss process of protons by the Whistler waves is found to approach one hour,comparable to that by the EMIC waves,suggesting that Whistler waves may also contribute significantly to the ring current decay under appropriate conditions.

  6. Current-voltage characteristic of a resonant tunneling diode under electromagnetic radiation

    Directory of Open Access Journals (Sweden)

    N Hatefi Kargan

    2013-09-01

    Full Text Available  In this paper, current-voltage characteristic of a resonant tunneling diode under electromagnetic radiation has been calculated and compared with the results when there is no electromagnetic radiation. For calculating current -voltage characteristic, it is required to calculate the transmission coefficient of electrons from the well and barrier structures of this device. For calculating the transmission coefficient of electrons at the presence of electromagnetic radiation, Finite Difference Time Domain (FDTD method has been used and when there is no electromagnetic radiation Transfer Matrix Method (TMM and finite diffirence time domain method have been used. The results show that the presence of electromagnetic radiation causes resonant states other than principal resonant state (without presence of electromagnetic radiation to appear on the transmition coefficient curve where they are in distances from the principal peak and from each other. Also, the presence of electromagnetic radiation causes peaks other than principal peak to appear on the current-voltage characteristics of the device. Under electromagnetic radiation, the number of peaks on the current-voltage curve is smaller than the number of peaks on the current-voltage transmission coefficient. This is due to the fact that current-voltage curve is the result of integration on the energy of electrons, Thus, the sharper and low height peaks on the transmission coefficient do not appear on the current-voltage characteristic curve.

  7. Resonance Chiral Lagrangian Currents and Experimental Data for $\\tau^-\\to\\pi^{-}\\pi^{-}\\pi^{+}\

    CERN Document Server

    Nugent, I M; Roig, P; Shekhovtsova, O; Was, Z

    2013-01-01

    In this paper we document the modifications introduced to the previous version of the Resonance Chiral Lagrangian current ({\\it Phys.Rev.} {\\bf D86} (2012) 113008) of the $\\tau^\\pm \\to \\pi^\\pm \\pi^\\pm \\pi^\\mp \

  8. Ionic currents underlying difference in light response between type A and type B photoreceptors.

    Science.gov (United States)

    Blackwell, K T

    2006-05-01

    In Hermissenda crassicornis, the memory of light associated with turbulence is stored as changes in intrinsic and synaptic currents in both type A and type B photoreceptors. These photoreceptor types exhibit qualitatively different responses to light and current injection, and these differences shape the spatiotemporal firing patterns that control behavior. Thus the objective of the study was to identify the mechanisms underlying these differences. The approach was to develop a type B model that reproduced characteristics of type B photoreceptors recorded in vitro, and then to create a type A model by modifying a select number of ionic currents. Comparison of type A models with characteristics of type A photoreceptors recorded in vitro revealed that type A and type B photoreceptors have five main differences, three that have been characterized experimentally and two that constitute hypotheses to be tested with experiments in the future. The three differences between type A and type B photoreceptors previously characterized include the inward rectifier current, the fast sodium current, and conductance of calcium-dependent and transient potassium channels. Two additional changes were required to produce a type A photoreceptor model. The very fast firing frequency observed during the first second after light onset required a faster time constant of activation of the delayed rectifier. The fast spike adaptation required a fast, noninactivating calcium-dependent potassium current. Because these differences between type A and type B photoreceptors have not been confirmed in comparative experiments, they constitute hypotheses to be tested with future experiments.

  9. Studying the Effects of Transcranial Direct-Current Stimulation in Stroke Recovery Using Magnetic Resonance Imaging

    OpenAIRE

    Stagg, Charlotte J; Johansen-Berg, Heidi

    2013-01-01

    Transcranial direct-current stimulation (tDCS) is showing increasing promise as an adjunct therapy in stroke rehabilitation. However questions still remain concerning its mechanisms of action, which currently limit its potential. Magnetic resonance (MR) techniques are increasingly being applied to understand the neural effects of tDCS. Here, we review the MR evidence supporting the use of tDCS to aid recovery after stroke and discuss the important open questions that remain.

  10. Studying The Effects Of Transcranial Direct Current Stimulation In Stroke Recovery Using Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Charlotte J Stagg

    2013-12-01

    Full Text Available Transcranial direct current stimulation (tDCS is showing increasing promise as an adjunct therapy in stroke rehabilitation. However questions still remain concerning its mechanisms of action, which currently limit its potential. Magnetic Resonance (MR techniques are increasingly being applied to understand the neural effects of tDCS. Here, we review the MR evidence supporting the use of tDCS to aid recovery after stroke and discuss the important open questions that remain.

  11. Multi-frequency proportional-resonant (MFPR) current controller for PWM VSC under unbalanced supply conditions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This letter presents a multi-frequency proportional-resonant (MFPR) current controller developed for PWM voltage source converter (VSC) under the unbalanced supply voltage conditions. The delta operator is used in place of the shift operator for the implementation of MFPR by using a low-cost fixed-point DSP. The experimental results with an alternative control strategy validated the feasibility of the proposed MFPR current controller for the PWM VSC during voltage unbalance.

  12. Resonant Charge Current in a Rashba Ring Induced by Spin-Dependent Potential

    Institute of Scientific and Technical Information of China (English)

    JIANG Zhan-Feng; LI Hong

    2008-01-01

    A one-dimensional ring subject to Rashba spin-orbit coupling is investigated. When it is attached to a lead with spin-dependent chemical potential, there will be charge current in the ring. The charge current response is resonantly maximized when the Fermi energy of the lead is equal to any energy level of the 1D ring. And if two probes are attached to the ring, the electric voltage between them creates sawtooth-like wave, which indicates the direction of the charge current. A ferromagnetic lead can also induce persistent charge current, which can be detected by magnetization intensity measurement.

  13. Electrically tunable Fano-type resonance of an asymmetric metal wire pair.

    Science.gov (United States)

    Fu, Quanhong; Zhang, Fuli; Fan, Yuancheng; He, Xuan; Qiao, Tong; Kong, Botao

    2016-05-30

    We theoretically and experimentally investigate the electrically tunable Fano-type resonance of asymmetric metal wire pair loaded with varactor diodes. It is illustrated that Fano-type transmission spectrum with high quality factor Q appears as a result of interference between the dipole and quadrupole modes. The ohmic loss of series resistance in varactor diode makes major contribution to absorption. At the Fano-type resonance frequency, both the two metal wires exhibit the strongest electric resonance simultaneously, and the Fano-type resonance manifests a large group delay. As the bias voltage ranges from 0 V to 8 V, the Fano-type resonance frequency exhibits a prominent blueshift of 0.16 GHz and the transmission experiences a modulation with a modulation depth of 97%.

  14. Comparison of Return Stroke Current Profiles for Transmission-Line-Type and Traveling-Current-Source-Type Models

    Directory of Open Access Journals (Sweden)

    J.O. Adepitan

    2012-05-01

    Full Text Available The study is aimed at determining the dependence of the current along a channel on the model used, assuming the same base current. We compared three transmission-line-type models, namely: Transmission Line (TL, Modified Transmission Line with Linear decay, Modified Transmission Line with Exponential decay and two traveling-current-source-type models: Bruce-Golde (BG and Traveling Current Source (TCS models. The current profiles along the channel at different heights predicted by these models are presented and discussed. Comparison is based on the assumption that all the models have the same base current. It was found that at low heights and within a time window frame of 15 :s, the currents of the transmission-line-type models predict a zero value at one time or the other with a maximum turning point following some 1:s after. A linear relationship is predicted between the current peak and the channel height. A discontinuity of current peak was observed at high heights. No zero value of current was recorded in case of TCS both at low and high channel heights.

  15. Effect of Alfvén resonance on low-frequency fast wave current drive

    Science.gov (United States)

    Wang, C. Y.; Batchelor, D. B.; Carter, M. D.; Jaeger, E. F.; Stallings, D. C.

    1995-08-01

    The Alfvén resonances may occur on the low- and high-field sides for a low-frequency fast wave current drive scenario proposed for the International Thermonuclear Experimental Reactor (ITER) [Nucl. Fusion 31, 1135 (1991)]. At the resonance on the low-field side, the fast wave may be mode converted into a short-wavelength slow wave, which can be absorbed by electrons at the plasma edge, before the fast wave propagates into the core area of the plasma. Such absorption may cause a significant parasitic power loss.

  16. Effect of Alfven resonance on low-frequency fast wave current drive

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.Y.; Batchelor, D.B.; Carter, M.D.; Jaeger, E.F.; Stallings, D.C. [Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    1995-07-01

    The Alfven resonances may occur on the low- and high-field sides for a low-frequency fast wave current drive scenario proposed for the International Thermonuclear Experimental Reactor (ITER) [Nucl. Fusion {bold 31}, 1135 (1991)]. At the resonance on the low-field side, the fast wave may be mode converted into a short-wavelength slow wave, which can be absorbed by electrons at the plasma edge, before the fast wave propagates into the core area of the plasma. Such absorption may cause a significant parasitic power loss. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  17. Multiple resonances of a moving, oscillating surface disturbance on a shear current

    CERN Document Server

    Li, Yan

    2016-01-01

    We consider waves radiated by a disturbance of oscillating strength moving at constant velocity along the free surface of a shear flow which, when undisturbed, has uniform horizontal vorticity of magnitude $S$. When no current is present the problem is a classical one and much studied, and in deep water a resonance is known to occur when $\\tau=|\\boldsymbol{V}|\\omega_0/g$ equals the critical value $1/4$ ($\\boldsymbol{V}$: velocity of disturbance, $\\omega_0$: oscillation frequency, $g$: gravitational acceleration). We show that the presence of the sub-surface shear current can change this picture radically. Not only does the resonant value of $\\tau$ depend strongly on the angle between $\\boldsymbol{V}$ and the current's direction and the "shear-Froude number" $\\mathrm{Frs}=|\\boldsymbol{V}|S/g$; when $\\mathrm{Frs}>1/3$, multiple resonant values --- as many as $4$ --- can occur for some directions of motion. At sufficiently large values of $\\mathrm{Frs}$, the smallest resonance frequency tends to zero, representi...

  18. Stator Current Harmonic Control with Resonant Controller for Doubly Fed Induction Generator

    DEFF Research Database (Denmark)

    Liu, Changjin; Blaabjerg, Frede; Chen, Wenjie;

    2012-01-01

    Voltage harmonics in the grid can introduce stator current harmonics in a doubly fed induction generator (DFIG) wind turbine system, which may potentially impact the generated power quality. Therefore, wind turbine current controllers need to be designed to eliminate the impact of grid voltage...... rotor current control loop for harmonic suppression. The overall control scheme is implemented in dq frame. Based on a mathematical model of the DFIG control system, the effects on system stability using the resonant controller, an analysis of the steady-state error, and the dynamic performance...

  19. The design and fabrication on gate type resonant tunneling transistor

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In light of fabricating resonant tunneling diode(RTD),in this paper a GaAs-based resonant tunneling transistor with gate structure(GRTT)has been designed and fabricated successfully.A systematic depiction centers on the designs of material structure,device structure,photo lithography mask,fabrication of device and the measurement and analysis of parameters.The fabricated GRTT has a maximum PVCR of 46 and a maximum transconductance of 8 mS.The work lays the foundation for further improvement on the performance and parameters of RTT.

  20. Current molecular methods in epidemiological typing of Acinetobacter baumannii.

    Science.gov (United States)

    Rafei, Rayane; Kempf, Marie; Eveillard, Matthieu; Dabboussi, Fouad; Hamze, Monzer; Joly-Guillou, Marie-Laure

    2014-01-01

    The emergence of Acinetobacter baumannii during recent decades as an important nosocomial pathogen responsible of worldwide, intensively documented, outbreaks has resulted in a need for effective epidemiological typing methods. Throughout the years, many typing methods for A. baumannii epidemiological studies have been proposed from phenotypic to molecular methods. Currently, the use of phenotypic typing methods have declined considerably and been progressively replaced by molecular methods. In this review, we introduce the current molecular methods available for A. baumannii typing. Each method has its own advantages and disadvantages, and the selection of an appropriate genotyping method depends on studied objectives. This review sheds light on questions in different epidemiological settings and most molecular methods used to fit these objectives.

  1. Potassium currents in type II vestibular hair cells isolated from the guinea-pig's crista ampullaris.

    Science.gov (United States)

    Griguer, C; Kros, C J; Sans, A; Lehouelleur, J

    1993-11-01

    Type II vestibular hair cells were isolated from cristae ampullares of guinea-pig and maintained in vitro for 2-3 h. Outward membrane currents were studied under whole-cell voltage-clamp conditions. Type II hair cells had resting potentials of about -45 mV. Depolarizing voltage steps from a holding potential of -80 or -90 mV induced time- and voltage-dependent outward currents which slowly decayed to a sustained level. Tail currents reversed at about -70 mV, indicating that the outward currents were mainly carried by potassium ions. The currents had an activation threshold around -50 mV. The transient component was completely removed by a depolarizing pre-pulse positive to -10 mV. While bath application of 4-aminopyridine (5 mM) reduced both components, extracellular tetraethylammonium (10 mM) or zero calcium preferentially diminished the sustained current. We conclude that at least two potassium conductances are present, a delayed rectifier with a relatively fast inactivation and a calcium-dependent potassium current. Depolarizing current injections induced an electrical resonance in the voltage responses, with a frequency of 25-100 Hz, larger currents causing higher frequencies.

  2. Recognition of resonance type in periodically forced oscillators

    NARCIS (Netherlands)

    Broer, H.W.; Holtman, S.J.; Vegter, G.

    2010-01-01

    This paper deals with families of periodically forced oscillators undergoing a Hopf-Neimarck-Sacker bifurcation. The interest is in the corresponding resonance sets, regions in parameter space for which subharmonics occur. It is a classical result that the local geometry of these sets in the non-deg

  3. Euclidean resonance and a new type of nuclear reactions

    CERN Document Server

    Ivlev, B I

    2003-01-01

    The extremely small probability of quantum tunneling through an almost classical potential barrier may become not small under the action of the specially adapted nonstationary field. The tunneling rate has a sharp peak as a function of the particle energy when it is close to the certain resonant value defined by the nonstationary field (Euclidean resonance). Alpha decay of nuclei has a small probability since the alpha particle should tunnel through a very nontransparent Coulomb barrier. The incident proton, due to the Coulomb interaction with the tunneling alpha particle, plays the role of a nonstationary field which may result in Euclidean resonance in tunneling of the alpha particle. At the resonant proton energy, which is of the order of 0.2 Mev, the alpha particle escapes the nucleus and goes to infinity with no influence of the nuclear Coulomb barrier. The process is inelastic since the alpha particle releases energy and the proton gains it. This stimulation of alpha decay by a proton constitutes a new ...

  4. A new type of resonant neutrino conversions induced by magnetic fields

    CERN Document Server

    Sahu, S; Valle, José W F

    1995-01-01

    We consider resonant neutrino conversions in magnetised matter, such as a degenerate electron gas. We show how magnetisation effects caused by axial vector interactions of neutrinos with the charged leptons in the medium can induce a new type of resonant neutrino conversion which may occur even in situations where the MSW effect does not occur, such as the case of degenerate or inverted neutrino mass spectra. Our new resonance may simultaneously affect anti-neutrino \\bar{\

  5. High-frequency current oscillations in graphene-boron nitride resonant tunnel diodes

    Science.gov (United States)

    Greenaway, Mark; Gaskell, Jenn; Eaves, Laurence; Novoselov, Kostya; Mishchenko, Artem; Geim, Andre; Fromhold, Mark

    The successful realisation of multilayer graphene-hBN-graphene resonant tunnelling diodes (graphene- RTDs) with negative differential conductance (NDC) and MHz current oscillations offers the exciting possibility of exploiting them as high-frequency oscillators and mixers. In this paper, we examine their potential for generating higher frequencies by simulating the oscillations in the tunnel current and charge that arise when the device is biased in the NDC region and placed in a resonant circuit. Using the Bardeen transfer Hamiltonian method, we examine the effect on the device characteristics of the twist angle, θ, between the two graphene electrodes, the hBN barrier thickness and of the carrier density in the graphene electrodes, which can be adjusted by chemical doping or by an applied bias voltage. The simulations accurately reproduce our recently-reported measurements on these RTDs (Fig. 4,). The results of simulations show that frequencies of tens of GHz are achievable by optimising the device parameters. Leverhulme Trust, UK.

  6. Developments in near electrical resonance signal enhancement (NERSE) eddy-current methods

    Science.gov (United States)

    Hughes, Robert; Dixon, Steve

    2015-03-01

    In industry, the detection of small defects above a background noise threshold is always a limiting factor. This is true for even the most sensitivity and reliable of NDT techniques. However, defect signals in eddy-current (EC) inspections have the potential to be boosted above noise thresholds by exploiting the near electrical resonance signal enhancement (NERSE) phenomena, resulting from resonant frequency-shifting of an EC system as the coil passes over a defect. Following on from the observation and characterisation of this phenomenon, NERSE based EC methods are being investigated and developed for the detection of sub-millimeter surface defects in Aerospace superalloys. This paper discusses current advances in the development of such techniques and explores the potential of NERSE exploitation as well as examining its limitations.

  7. A High Voltage High Frequency Resonant Inverter for Supplying DBD Devices with Short Discharge Current Pulses

    OpenAIRE

    Bonnin, Xavier; Brandelero, Julio; Videau, Nicolas; Piquet, Hubert; Meynard, Thierry

    2014-01-01

    International audience; In this paper, the merits of a high-frequency resonant converter for supplying dielectric barrier discharges (DBD) devices are established. It is shown that, thanks to its high-frequency operating condition, such a converter allows to supply DBD devices with short discharge current pulses, a high repetition rate, and to control the injected power. In addition, such a topology eliminates the matter of connecting a high-voltage transformer directly across the DBD device ...

  8. The resonant, near-resonant, and off-resonant plasmon coupling effects for the bonding modes in two types of asymmetric dimer

    Science.gov (United States)

    Li, Quanshui; Hu, Jianling; Wang, Ziya; Wang, Fengping; Bao, Yongjun

    2014-07-01

    The resonant, near-resonant, and off-resonant plasmon coupling effects for the bonding modes in asymmetric dimers are illustrated by two types of configuration, one formed by a gold nanoparticle and a TiO2-Ag core-shell nanoparticle and the other formed by two TiO2-Ag core-shell nanoparticles with suitable sizes. The redshift and blueshift behaviours of the coupled bonding modes with decreasing gap are found under longitudinal and transverse polarization of light for these dimers in the resonant situation, respectively. Under the near-resonant situation, the redshift behaviours of the coupled bonding modes still remain under longitudinal polarization, whereas the two separated modes of monomers after coupling under transverse polarization exhibit no obvious peak-shift behaviours, and the one on the lower frequency side shows an apparent attenuation in the strength. Under the off-resonant situation, the redshift behaviours not only occur in the coupled modes under longitudinal polarization, but also occur in two separated modes under transverse polarization.

  9. Design study of a beta=0.09 high current superconducting half wave resonator

    CERN Document Server

    Zhong, Hu-Tan-Xiang; Fan, Pei-Liang; Quan, Sheng-Wen; Liu, Ke-Xin

    2016-01-01

    There's presently a growing demand for high current proton and deuteron linear accelerators based on superconducting technology to better support various fields of science. A \\b{eta}=0.09 162.5 MHz high current superconducting half wave resonator (HWR) has been designed at Peking University to accelerate 100 mA proton beam or 50 mA deuteron beam after the RFQ accelerating structure. The detailed electromagnetic design, multipacting simulation, mechanical analysis of the cavity will be given in this paper.

  10. Induced current magnetic resonance electrical impedance tomography with z-gradient coil.

    Science.gov (United States)

    Eroğlu, Hasan H; Eyüboğlu, B Murat

    2014-01-01

    Magnetic Resonance Electrical Impedance Tomography (MREIT) is a medical imaging method that provides images of electrical conductivity at low frequencies (0-1 kHz). In MREIT, electrical current is applied to the body via surface electrodes and corresponding magnetic flux density is measured by means of Magnetic Resonance (MR) phase imaging techniques. By utilizing the magnetic flux density measurements and surface potential measurements images of true conductivity distribution can be reconstructed. In order to overcome difficulties regarding current application via surface electrodes, Induced Current MREIT (ICMREIT) have been proposed in the past. In ICMREIT, electrical currents and corresponding magnetic flux density are generated in the object through electromagnetic induction by means of externally placed coils driven with time varying currents. In this study, use of z-gradient, z-Helmholtz, and circular coil configurations in ICMREIT are proposed and investigated. Finite Element Method (FEM) is used to solve the forward problem of ICMREIT. Consequently, excitation performances and clinical applicability of different coil configurations are analyzed.

  11. Enhanced infrared detectors using resonant structures combined with thin type-II superlattice absorbers

    Science.gov (United States)

    Goldflam, M. D.; Kadlec, E. A.; Olson, B. V.; Klem, J. F.; Hawkins, S. D.; Parameswaran, S.; Coon, W. T.; Keeler, G. A.; Fortune, T. R.; Tauke-Pedretti, A.; Wendt, J. R.; Shaner, E. A.; Davids, P. S.; Kim, J. K.; Peters, D. W.

    2016-12-01

    We examined the spectral responsivity of a 1.77 μm thick type-II superlattice based long-wave infrared detector in combination with metallic nanoantennas. Coupling between the Fabry-Pérot cavity formed by the semiconductor layer and the resonant nanoantennas on its surface enables spectral selectivity, while also increasing peak quantum efficiency to over 50%. Electromagnetic simulations reveal that this high responsivity is a direct result of field-enhancement in the absorber layer, enabling significant absorption in spite of the absorber's subwavelength thickness. Notably, thinning of the absorbing material could ultimately yield lower photodetector noise through a reduction in dark current while improving photocarrier collection efficiency. The temperature- and incident-angle-independent spectral response observed in these devices allows for operation over a wide range of temperatures and optical systems. This detector paradigm demonstrates potential benefits to device performance with applications throughout the infrared.

  12. Resonant dipolar relaxation in poly ( ɛ -caprolactone)—A thermally stimulated depolarization current study

    Science.gov (United States)

    Patidar, M. M.; Jain, D.; Nath, R.; Ganesan, V.

    2016-07-01

    Resonant dipolar relaxation in poly( ɛ-caprolactone) (PCL) is reported using thermally stimulated discharge current spectroscopy. PCL is a bio-medically known shape memory polymer having a well defined γ, β, α, and α ' relaxations, respectively, centered around 125 K, 170 K, 220 K, and 270 K as seen by the measurements. By employing a new protocol variable poling temperature at constant freezing temperature, resonant dipolar relaxation in PCL could be induced, especially in the vicinity of α relaxation. Such a protocol is useful in de-convoluting the features in a more meaningful fashion. By an analysis of activation process, we could show a clear contrast enhancement of the dynamics of the participating dipoles by means of a minimum in the activation energies situated around the glass transition region. The relevant parameters of interest such as activation energies and relaxation times are estimated and discussed.

  13. Coupling between Surface Plasmon Resonance and electric current in Au stripes

    Science.gov (United States)

    Garcia, Miguel Angel; Serrano, Aida; de La Venta, Jose

    2009-03-01

    Surface Plasmon Resonance (SPR) is the most outstanding feature of noble metal films. SPR consists on a collective oscillation of the conduction electrons when excited optically in the appropriate geometrical and energy conditions. The electrical current passing trough the metal film involves also the movement of conduction electrons. Thus, coupling effects are expected between SPR and electrical resistivity. A modification of the SPR when a electrical current passes through the film, could allow the modulation of an optical signal by a electrical one. Similarly, when the film is illuminated at the SPR conditions, the oscillation of the conduction electrons and local heating can induce an enhancement of the electric resistivity that can be used to translate an optical signal into a electric one. Those effects could be useful in the development of new fast optoelectronic transducers. We present here results on Au stripes illuminated to induce the SPR while electric currents flow with different orientation with respect to the light polarization

  14. Detectability of Neuronal Currents in Human Brain with Magnetic Resonance Spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Howland D. T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Thomas, Edward V. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Harper, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mayer, Andrew R. [Mind Research Network, Albuquerque, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States); Caprihan, Arvind [Mind Research Network, Albuquerque, NM (United States); Gasparovic, Charles [Mind Research Network, Albuquerque, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States); Blagoev, Krastan B. [Mind Research Network, Albuquerque, NM (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Haaland, David M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2012-09-01

    Magnetic resonance spectroscopy has been used in a high-risk, high-payoff search for neuronal current (NC) signals in the free induction decay (FID) data from the visual cortex of human subjects during visual stimulation. If successful, this approach could make possible the detection of neuronal currents in the brain at high spatial and temporal resolution. Our initial experiments indicated the presence of a statistically significant change in the FID containing the NC relative to FIDs with the NC absent, and this signal was consistent with the presence of NC. Unfortunately, two follow-on experiments were not able to confirm or replicate the positive findings of the first experiment. However, even if the result from the first experiment were evidence of NC in the FID, it is clear that its effect is so small, that a true NC imaging experiment would not be possible with the current instrumentation and experimental protocol used here.

  15. Electrically stimulated high-frequency replicas of a resonant current in GaAs/AlAs resonant-tunneling double-barrier THz nanostructures

    Science.gov (United States)

    Aleksanyan, A. A.; Karuzskii, A. L.; Kazakov, I. P.; Mityagin, Yu. A.; Murzin, V. N.; Perestoronin, A. V.; Shmelev, S. S.; Tskhovrebov, A. M.

    2016-12-01

    The periodical-in-voltage features of the negative differential conductance (NDC) region in the current-voltage characteristics of a high-quality GaAs/AlAs terahertz resonant-tunneling diode have been detected. The found oscillations are considered taking account of the LO-phonon excitation stimulated by tunneling of electrons through the quantum active region in the resonance nanostructure where an undoped quantum well layer is sandwiched between two undoped barrier layers. Rearrangements in the I-V characteristics of the resonant-tunneling diode as a consequence of the topological transformation of a measurement circuit from the circuit with the series resistance Rs to the circuit with the shunt Rp have been experimentally studied and analyzed. The revealed substantial changes in the current-voltage characteristics of the resonant-tunneling diode are discussed schematically using Kirchhoff's voltage law.

  16. Conductive shield for ultra-low-field magnetic resonance imaging: Theory and measurements of eddy currents

    Science.gov (United States)

    Zevenhoven, Koos C. J.; Busch, Sarah; Hatridge, Michael; Öisjöen, Fredrik; Ilmoniemi, Risto J.; Clarke, John

    2014-03-01

    Eddy currents induced by applied magnetic-field pulses have been a common issue in ultra-low-field magnetic resonance imaging. In particular, a relatively large prepolarizing field—applied before each signal acquisition sequence to increase the signal—induces currents in the walls of the surrounding conductive shielded room. The magnetic-field transient generated by the eddy currents may cause severe image distortions and signal loss, especially with the large prepolarizing coils designed for in vivo imaging. We derive a theory of eddy currents in thin conducting structures and enclosures to provide intuitive understanding and efficient computations. We present detailed measurements of the eddy-current patterns and their time evolution in a previous-generation shielded room. The analysis led to the design and construction of a new shielded room with symmetrically placed 1.6-mm-thick aluminum sheets that were weakly coupled electrically. The currents flowing around the entire room were heavily damped, resulting in a decay time constant of about 6 ms for both the measured and computed field transients. The measured eddy-current vector maps were in excellent agreement with predictions based on the theory, suggesting that both the experimental methods and the theory were successful and could be applied to a wide variety of thin conducting structures.

  17. Conductive shield for ultra-low-field magnetic resonance imaging: Theory and measurements of eddy currents.

    Science.gov (United States)

    Zevenhoven, Koos C J; Busch, Sarah; Hatridge, Michael; Oisjöen, Fredrik; Ilmoniemi, Risto J; Clarke, John

    2014-03-14

    Eddy currents induced by applied magnetic-field pulses have been a common issue in ultra-low-field magnetic resonance imaging. In particular, a relatively large prepolarizing field-applied before each signal acquisition sequence to increase the signal-induces currents in the walls of the surrounding conductive shielded room. The magnetic-field transient generated by the eddy currents may cause severe image distortions and signal loss, especially with the large prepolarizing coils designed for in vivo imaging. We derive a theory of eddy currents in thin conducting structures and enclosures to provide intuitive understanding and efficient computations. We present detailed measurements of the eddy-current patterns and their time evolution in a previous-generation shielded room. The analysis led to the design and construction of a new shielded room with symmetrically placed 1.6-mm-thick aluminum sheets that were weakly coupled electrically. The currents flowing around the entire room were heavily damped, resulting in a decay time constant of about 6 ms for both the measured and computed field transients. The measured eddy-current vector maps were in excellent agreement with predictions based on the theory, suggesting that both the experimental methods and the theory were successful and could be applied to a wide variety of thin conducting structures.

  18. Optimization of negative ion current in a compact microwave driven upper hybrid resonance multicusp plasma source.

    Science.gov (United States)

    Sahu, D; Bhattacharjee, S; Singh, M J; Bandyopadhyay, M; Chakraborty, A

    2012-02-01

    Performance of a microwave driven upper hybrid resonance multicusp plasma source as a volume negative ion source is reported. Microwaves are directly launched into the plasma chamber predominantly in the TE(11) mode. The source is operated at different discharge conditions to obtain the optimized negative H(-) ion current which is ∼33 μA (0.26 mA∕cm(2)). Particle balance equations are solved to estimate the negative ion density, which is compared with the experimental results. Future prospects of the source are discussed.

  19. Optimization of negative ion current in a compact microwave driven upper hybrid resonance multicusp plasma sourcea)

    Science.gov (United States)

    Sahu, D.; Bhattacharjee, S.; Singh, M. J.; Bandyopadhyay, M.; Chakraborty, A.

    2012-02-01

    Performance of a microwave driven upper hybrid resonance multicusp plasma source as a volume negative ion source is reported. Microwaves are directly launched into the plasma chamber predominantly in the TE11 mode. The source is operated at different discharge conditions to obtain the optimized negative H- ion current which is ˜33 μA (0.26 mA/cm2). Particle balance equations are solved to estimate the negative ion density, which is compared with the experimental results. Future prospects of the source are discussed.

  20. Semiclassical description of resonant tunnel effect: bifurcations and periodic orbits in the resonant current; Description semiclassique de l`effet tunnel resonant: bifurcations et orbites periodiques dans le courant resonant

    Energy Technology Data Exchange (ETDEWEB)

    Rouben, D.C

    1997-11-28

    A semiclassical method for resonant tunneling in a quantum well in the presence of a magnetic field tilted with regard to an electric field is developed. In particular a semiclassical formula is derived for the total current of electrons after the second barrier of the quantum well. The contribution of the stable and unstable orbits is studied. It appears that the parameters which describe the classical chaos in the quantum well have an important effect on the tunneling current. A numerical experiment is led, the contributions to the current of some particular orbits are evaluated and the results are compared with those given by the quantum theory. (A.C.) 70 refs.

  1. A 5 GHz high-temperature superconducting reaction-type transmitting filter based upon split open-ring resonators

    Energy Technology Data Exchange (ETDEWEB)

    Futatsumori, S; Hikage, T; Nojima, T [Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-0814 (Japan); Akasegawa, A; Nakanishi, T; Yamanaka, K [Fujitsu Limited, 10-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0197 (Japan)], E-mail: futatsumori@emwtinfo.ice.eng.hokudai.ac.jp

    2008-04-01

    A new kind of high-temperature superconducting (HTS) transmitting filter based on a reaction-type resonator is presented. The purpose of an HTS reaction-type filter (HTS-RTF) is to eliminate the intermodulation distortion noise generated by microwave power amplifiers such as those employed in mobile base stations. An HTS-RTF enables both higher power handling capability and sharper cutoff characteristics compared to existing planar-type HTS transmitting filters, since a reaction-type resonator does not resonate with high power fundamental signals. To achieve steep skirt characteristics and high power handling capability simultaneously, a 5 GHz three-pole HTS-RTF using a split open-ring resonator is designed. This split open-ring resonator offers low maximum current densities and a high-unloaded Q factor with low radiation. The designed prototype filter has Chebyshev characteristics with a centre frequency of 4.95 GHz and a bandwidth of 1.5 MHz. The HTS-RTF is fabricated using a double-sided YBa{sub 2}C{sub 3}O{sub 7-{delta}} thin film deposited on a 0.5 mm thick MgO substrate. The measured filter shows an insertion loss of less than 0.1 dB and a third intermodulation distortion value of -56.7 dBc for a 40 dBm passband signal. In addition, adjacent channel leakage power ratio (ACLR) measurements using an actual wideband CDMA signal confirm an ACLR improvement of about 10 dB for a four-carrier signal with power up to 40 dBm.

  2. Comparison of three EIT-type resonances formed in Rb nanocell

    Science.gov (United States)

    Sargsyan, Armen; Sarkisyan, David; Margalit, Leah; Wilson-Gordon, Arlene D.

    2016-09-01

    The electromagnetically induced transparency (EIT) phenomenon is studied using a nanometric thin (L = 795 nm) Rb vapour layer. EIT-type resonances that are formed in three different energy-level systems are reported. It is demonstrated that the EIT resonance which is formed in a Λ-system where the ground levels are separated by the hyperfine splitting (EITH-resonance) has the smallest linewidth (~10 MHz). The EIT resonance which is realized in a Λ-system formed by the Zeeman sublevels of the Fg = 2 → Fe = 1 transition (EITZ-resonance) has a larger linewidth (~14 MHz). The EITV-resonance which is formed in the V-system has the largest linewidth (~40 MHz). The uniqueness of the EIT phenomena reported here is that they can be formed in different types of Λ-systems even for L < 1 μm. The splitting of the EITZ-resonance into two components in a transverse magnetic field is reported. The theoretical model well describes the experiment.

  3. Cyclotron resonance of figure-of-eight orbits in a type-II Weyl semimetal

    Science.gov (United States)

    Koshino, Mikito

    2016-07-01

    We study the cyclotron resonance in the electron-hole joint Fermi surface of a type-II Weyl semimetal. In magnetic field, the electron and hole pockets touching at the Weyl node are hybridized to form quantized Landau levels corresponding to semiclassical 8-shaped orbits. We calculate the dynamical conductivities for the electric fields oscillating in x and y directions and find that the resonant frequencies in x and y differ by a factor of two, reflecting the figure-of-eight electron motion in real space. The peculiar anisotropy in the cyclotron resonance serves as a unique characteristic of the dumbbell-like Fermi surface.

  4. Magnetic resonance imaging in psoriatic arthritis -- update on current status and future perspectives

    DEFF Research Database (Denmark)

    Østergaard, Mikkel; Poggenborg, René Panduro

    2012-01-01

    Measures in Rheumatology) may contribute to facilitating research, identifying appropriate areas for use, and reaching consensus on the optimal examination technique. Accordingly, GRAPPA, a primary driver of international research in psoriasis and psoriatic arthritis (PsA), has focused on the current use......The potential of magnetic resonance imaging (MRI) for use in clinical practice and research has gained increasing interest over the last decade. International collaborative initiatives from GRAPPA (Group for Research and Assessment of Psoriasis and Psoriatic Arthritis) and/or OMERACT (Outcome...... and future development of MRI and other modern imaging modalities in PsA. This review, presented at the GRAPPA 2010 annual meeting, describes the current status of MRI in PsA, with a focus on its use in diagnosis, monitoring, and prediction of the disease course and treatment response. Important areas...

  5. Capacitor Current Feedback-Based Active Resonance Damping Strategies for Digitally-Controlled Inductive-Capacitive-Inductive-Filtered Grid-Connected Inverters

    Directory of Open Access Journals (Sweden)

    Iman Lorzadeh

    2016-08-01

    Full Text Available Inductive-capacitive-inductive (LCL-type line filters are widely used in grid-connected voltage source inverters (VSIs, since they can provide substantially improved attenuation of switching harmonics in currents injected into the grid with lower cost, weight and power losses than their L-type counterparts. However, the inclusion of third order LCL network complicates the current control design regarding the system stability issues because of an inherent resonance peak which appears in the open-loop transfer function of the inverter control system near the control stability boundary. To avoid passive (resistive resonance damping solutions, due to their additional power losses, active damping (AD techniques are often applied with proper control algorithms in order to damp the LCL filter resonance and stabilize the system. Among these techniques, the capacitor current feedback (CCF AD has attracted considerable attention due to its effective damping performance and simple implementation. This paper thus presents a state-of-the-art review of resonance and stability characteristics of CCF-based AD approaches for a digitally-controlled LCL filter-based grid-connected inverter taking into account the effect of computation and pulse width modulation (PWM delays along with a detailed analysis on proper design and implementation.

  6. Magnetic resonance electrical impedance tomography (MREIT): conductivity and current density imaging

    Science.gov (United States)

    Seo, Jin Keun; Kwon, Ohin; Woo, Eung Je

    2005-01-01

    This paper reviews the latest impedance imaging technique called Magnetic Resonance Electrical Impedance Tomography (MREIT) providing information on electrical conductivity and current density distributions inside an electrically conducting domain such as the human body. The motivation for this research is explained by discussing conductivity changes related with physiological and pathological events, electromagnetic source imaging and electromagnetic stimulations. We briefly summarize the related technique of Electrical Impedance Tomography (EIT) that deals with cross-sectional image reconstructions of conductivity distributions from boundary measurements of current-voltage data. Noting that EIT suffers from the ill-posed nature of the corresponding inverse problem, we introduce MREIT as a new conductivity imaging modality providing images with better spatial resolution and accuracy. MREIT utilizes internal information on the induced magnetic field in addition to the boundary current-voltage measurements to produce three-dimensional images of conductivity and current density distributions. Mathematical theory, algorithms, and experimental methods of current MREIT research are described. With numerous potential applications in mind, future research directions in MREIT are proposed.

  7. Resonance Type Instabilities in the Gaseous Disks of the Flat Galaxies I. The Acoustical Resonance Type Instability and the Absence of Vortex Sheet Stabilization on Shallow Water

    OpenAIRE

    Mustsevaya, J. V.; Mustsevoy, V. V.

    1998-01-01

    Linear analysis of vortex sheet stability in the rotating gaseous disk or shallow water layer shows that presence of a central reflecting surface changes system stability significantly. An effect of absence of vortex sheet stabilization has been found as compressibility exceeds Landau criterion. The properties of multimode short-scale instability of acoustical resonance type are investigated and probability of its influence upon experiments on the rotating shallow water is discussed.

  8. Resonance Type Instabilities in the Gaseous Disks of the Flat Galaxies 1 The Acoustical Resonance Type Instability and the Absence of Vortex Sheet Stabilization on Shallow Water

    CERN Document Server

    Mustsevaya, J V

    1998-01-01

    Linear analysis of vortex sheet stability in the rotating gaseous disk or shallow water layer shows that presence of a central reflecting surface changes system stability significantly. An effect of absence of vortex sheet stabilization has been found as compressibility exceeds Landau criterion. The properties of multimode short-scale instability of acoustical resonance type are investigated and probability of its influence upon experiments on the rotating shallow water is discussed.

  9. Current resonances and current platforms in a two-level InAs quantum dot with asymmetric terahertz irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, R.-Y., E-mail: yuanry@cnu.edu.cn [Center for Theoretical Physics, Department of Physics, Capital Normal University, Beijing 100048 (China); Zhao, X.; Ji, A.-C. [Center for Theoretical Physics, Department of Physics, Capital Normal University, Beijing 100048 (China); Guo, Y., E-mail: guoy66@tsinghua.edu.cn [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China); Yan, H. [Laboratory of Thin Film Materials, Beijing University of Technology, Beijing 100022 (China)

    2015-09-04

    Both the charging and orbital quantization energies of InAs quantum dot (QD) typically correspond to the terahertz (THz) region. In this letter, under the asymmetric THz irradiations on two leads, electron transport through a two-level InAs QD is theoretically discussed. We demonstrate that when both the frequencies and amplitudes of THz irradiations on two leads are different with the higher asymmetry, the photon–electron pump effect vanishes, even a negative platform appears on the left of the Coulomb peak and a positive platform occurs on the right of the Coulomb interaction related energy level, respectively. This behavior is favorable for the design of THz optoelectronic device. - Highlights: • Asymmetric terahertz waves are irradiated on two leads in two-level InAs QD system. • Only with different frequencies, a negative current resonance is obtained. • A negative platform appears on the left of the Coulomb peak with higher asymmetry. • For the low terahertz field strength, a positive platform occurs. • We report the behaviors are favorable for the design of THz optoelectronic device.

  10. Type 2 Diabetes Mellitus: A Review of Current Trends

    Directory of Open Access Journals (Sweden)

    Abdulfatai B. Olokoba

    2012-07-01

    Full Text Available Type 2 diabetes mellitus (DM is a chronic metabolic disorder in which prevalence has been increasing steadily all over the world. As a result of this trend, it is fast becoming an epidemic in some countries of the world with the number of people affected expected to double in the next decade due to increase in ageing population, thereby adding to the already existing burden for healthcare providers, especially in poorly developed countries. This review is based on a search of Medline, the Cochrane Database of Systemic Reviews, and citation lists of relevant publications. Subject heading and key words used include type 2 diabetes mellitus, prevalence, current diagnosis, and current treatment. Only articles in English were included. Screening and diagnosis is still based on World Health Organization (WHO and American Diabetes Association (ADA criteria which include both clinical and laboratory parameters. No cure has yet been found for the disease; however, treatment modalities include lifestyle modifications, treatment of obesity, oral hypoglycemic agents, and insulin sensitizers like metformin, a biguanide that reduces insulin resistance, is still the recommended first line medication especially for obese patients. Other effective medications include non-sulfonylurea secretagogues, thiazolidinediones, alpha glucosidase inhibitors, and insulin. Recent research into the pathophysiology of type 2 DM has led to the introduction of new medications like glucagon-like peptide 1 analogoues: dipeptidyl peptidase-IV inhibitors, inhibitors of the sodium-glucose cotransporter 2 and 11ß-hydroxysteroid dehydrogenase 1, insulin-releasing glucokinase activators and pancreatic-G-protein-coupled fatty-acid-receptor agonists, glucagon-receptor antagonists, metabolic inhibitors of hepatic glucose output and quick-release bromocriptine. Inhaled insulin was licensed for use in 2006 but has been withdrawn from the market because of low patronage.

  11. Shale characteristics impact on Nuclear Magnetic Resonance (NMR fluid typing methods and correlations

    Directory of Open Access Journals (Sweden)

    Mohamed Mehana

    2016-06-01

    Full Text Available The development of shale reservoirs has brought a paradigm shift in the worldwide energy equation. This entails developing robust techniques to properly evaluate and unlock the potential of those reservoirs. The application of Nuclear Magnetic Resonance techniques in fluid typing and properties estimation is well-developed in conventional reservoirs. However, Shale reservoirs characteristics like pore size, organic matter, clay content, wettability, adsorption, and mineralogy would limit the applicability of the used interpretation methods and correlation. Some of these limitations include the inapplicability of the controlling equations that were derived assuming fast relaxation regime, the overlap of different fluids peaks and the lack of robust correlation to estimate fluid properties in shale. This study presents a state-of-the-art review of the main contributions presented on fluid typing methods and correlations in both experimental and theoretical side. The study involves Dual Tw, Dual Te, and doping agent's application, T1-T2, D-T2 and T2sec vs. T1/T2 methods. In addition, fluid properties estimation such as density, viscosity and the gas-oil ratio is discussed. This study investigates the applicability of these methods along with a study of the current fluid properties correlations and their limitations. Moreover, it recommends the appropriate method and correlation which are capable of tackling shale heterogeneity.

  12. Growth and characterization of high current density, high-speed InAs/AlSb resonant tunneling diodes

    Science.gov (United States)

    Soderstrom, J. R.; Brown, E. R.; Parker, C. D.; Mahoney, L. J.; Yao, J. Y.

    1991-01-01

    InAs/AlSb double-barrier resonant tunneling diodes with peak current densities up to 370,000 A/sq cm and high peak-to-valley current ratios of 3.2 at room temperature have been fabricated. The peak current density is well-explained by a stationary-state transport model with the two-band envelope function approximation. The valley current density predicted by this model is less than the experimental value by a factor that is typical of the discrepancy found in other double-barrier structures. It is concluded that threading dislocations are largely inactive in the resonant tunneling process.

  13. Conductivity and current density image reconstruction using harmonic Bz algorithm in magnetic resonance electrical impedance tomography.

    Science.gov (United States)

    Oh, Suk Hoon; Lee, Byung Il; Woo, Eung Je; Lee, Soo Yeol; Cho, Min Hyoung; Kwon, Ohin; Seo, Jin Keun

    2003-10-07

    Magnetic resonance electrical impedance tomography (MREIT) is to provide cross-sectional images of the conductivity distribution sigma of a subject. While injecting current into the subject, we measure one component Bz of the induced magnetic flux density B = (Bx, By, Bz) using an MRI scanner. Based on the relation between (inverted delta)2 Bz and inverted delta sigma, the harmonic Bz algorithm reconstructs an image of sigma using the measured Bz data from multiple imaging slices. After we obtain sigma, we can reconstruct images of current density distributions for any given current injection method. Following the description of the harmonic Bz algorithm, this paper presents reconstructed conductivity and current density images from computer simulations and phantom experiments using four recessed electrodes injecting six different currents of 26 mA. For experimental results, we used a three-dimensional saline phantom with two polyacrylamide objects inside. We used our 0.3 T (tesla) experimental MRI scanner to measure the induced Bz. Using the harmonic Bz algorithm, we could reconstruct conductivity and current density images with 82 x 82 pixels. The pixel size was 0.6 x 0.6 mm2. The relative L2 errors of the reconstructed images were between 13.8 and 21.5% when the signal-to-noise ratio (SNR) of the corresponding MR magnitude images was about 30. The results suggest that in vitro and in vivo experimental studies with animal subjects are feasible. Further studies are requested to reduce the amount of injection current down to less than 1 mA for human subjects.

  14. Resonances

    DEFF Research Database (Denmark)

    an impetus or drive to that account: change, innovation, rupture, or discontinuity. Resonances: Historical Essays on Continuity and Change explores the historiographical question of the modes of interrelation between these motifs in historical narratives. The essays in the collection attempt to realize...... theoretical consciousness through historical narrative ‘in practice’, by discussing selected historical topics from Western cultural history, within the disciplines of history, literature, visual arts, musicology, archaeology, philosophy, and theology. The title Resonances indicates the overall perspective...

  15. Sub-natural $N$-type Resonance in Cesium Atomic Vapor: splitting in magnetic fields

    CERN Document Server

    Slavov, D; Sarkisyan, D; Mirzoyan, R; Krasteva, A; Wilson-Gordon, A D; Cartaleva, S

    2013-01-01

    The sub-natural-width $N$-type resonance in {\\Lambda}-system, on the $D_2$ line of Cs atoms is studied for the first time in the presence of a buffer gas (neon) and the radiations of two continuous narrow band diode lasers. $L$ = 1 cm long cell is used to investigate $N$-type process. The $N$-type resonance in a magnetic field for $^{133}$Cs atoms is shown to split into seven or eight components, depending on the magnetic field and laser radiation directions. The results obtained indicate that levels $F_g$ = 3, 4 are initial and final in the N resonance formation. The experimental results with magnetic field agree well with the theoretical curves.

  16. Molecular Dynamics Study on the Resonance Properties of a Nano Resonator Based on a Graphene Sheet with Two Types of Vacancy Defects

    Directory of Open Access Journals (Sweden)

    Wenchao Tian

    2017-01-01

    Full Text Available Due to the excellent electronic, optical, thermal, chemical, and mechanical properties of graphene, it has been applied in microdevices and nanodevices. However, there are some structural defects in graphene limiting its application in micro electromechanical systems (MEMS. These structural defects are inevitable during processing, and it is difficult to assess their effect on the micro/nano devices. Therefore, this communication used molecular dynamics to study the resonance properties of a nanoelectromechanical systems (NMES resonator based on a graphene sheet with a single vacancy defect and edge defects. This communication focuses on three factors: vacancy types, external force, and temperature. The resonance frequencies of both types of graphene increased with external stress loading, and the resonance frequency of the graphene showed a clear step-shaped variation. Nonlinear deformation of the sheet occurred between resonant processes. When the external force was less than 15.91 nN, the resonance frequencies of the two types of graphene showed a consistent trend. The maximum frequency was up to 132.90 GHz. When the external force was less than 90 nN, the resonance frequencies of graphene with edge defects were greater and changed more rapidly. Temperature did not have a huge influence on the resonance frequencies of either type of graphene structure. The resonance frequencies of graphene with two different vacancy defects showed a consistent trend.

  17. The role of magnetic resonance imaging in the evaluation of thalassemic syndromes: current practice and future perspectives

    Directory of Open Access Journals (Sweden)

    Sophie Mavrogeni

    2014-09-01

    Full Text Available Iron can be deposited in all internal organs, leading to different types of functional abnormalities. However, myocardial iron overload that contributes to heart failure remains one of the main causes of death in thalassemia major. Using magnetic resonance imaging, tissue iron is detected indirectly by the effects on relaxation times of ferritin and hemosiderin iron interacting with hydrogen nuclei. The presence of iron in the human body results in marked alterations of tissue relaxation times. Currently, cardiovascular magnetic resonance using T2* is routinely used in many countries to identify patients with myocardial iron loading and guide chelation therapy, specifically tailored to the heart. Myocardial T2* is the only clinically validated non-invasive measure of myocardial iron loading and is superior to surrogates such as serum ferritin, liver iron, ventricular ejection fraction and tissue Doppler parameters. Finally, the substantial amelioration of patients’ survival, allows the detection of other organs’ abnormalities due to iron overload, apart from the heart, missed in the past. Recent studies revealed that iron deposition has a different pattern in various parenchymal organs, which is independent from serum ferritin and follows an individual way after chelation treatment application. This new upcoming reality orders a closer monitoring of all organs of the body in order to detect preclinical lesions and early apply adequate treatment.

  18. Empirical compensation function for eddy current effects in pulsed field gradient nuclear magnetic resonance experiments.

    Science.gov (United States)

    Zhu, X X; Macdonald, P M

    1995-05-01

    An empirical compensation function for the correction of eddy current effects in the Stejskal-Tanner pulsed-gradient spin-echo (PGSE) nuclear magnetic resonance (NMR) experiments has been established. Eddy currents may arise as a result of the application of sharp and strong gradient pulses and may cause severe distortion of the NMR signals. In this method, the length of one gradient pulse is altered to compensate for the eddy current effects. The compensation is considered to be ideal when the position and the phase of the spin-echo maximum obtained from an aqueous solution of poly(ethylene glycol) (PEG) is the same in the presence and absence of a gradient pulse in the PGSE pulse sequence. We first characterized the functional dependence of the length of the required compensation on the three principal variables in the PGSE experiment: the gradient strength, the duration of the gradient pulse, and the interval between the two gradient pulses. Subsequently, we derived a model which successfully describes the general relationship between these variables and the size of the induced eddy current. The parameters extracted from fitting the model to the experimental compensation data may be used to predict the correct compensation for any combination of the three principal variables.

  19. Multiple endocrine neoplasia type 2: achievements and current challenges

    Directory of Open Access Journals (Sweden)

    Andreas Machens

    2012-01-01

    Full Text Available Incremental advances in medical technology, such as the development of sensitive hormonal assays for routine clinical care, are the drivers of medical progress. This principle is exemplified by the creation of the concept of multiple endocrine neoplasia type 2, encompassing medullary thyroid cancer, pheochromocytoma, and primary hyperparathyroidism, which did not emerge before the early 1960s. This review sets out to highlight key achievements, such as joint biochemical and DNA-based screening of individuals at risk of developing multiple endocrine neoplasia type 2, before casting a spotlight on current challenges which include: (i ill-defined upper limits of calcitonin assays for infants and young children, rendering it difficult to implement the biochemical part of the integrated DNA-based/biochemical concept; (ii our increasingly mobile society in which different service providers are caring for one individual at various stages in the disease process. With familial relationships disintegrating as a result of geographic dispersion, information about the history of the origin family may become sketchy or just unavailable. This is when DNA-based gene tests come into play, confirming or excluding an individual's genetic predisposition to multiple endocrine neoplasia type 2 even before there is any biochemical or clinical evidence of the disease. However, the unrivaled molecular genetic progress in multiple endocrine neoplasia type 2 does not come without a price. Screening may uncover unknown gene sequence variants representing either harmless polymorphisms or pathogenic mutations. In this setting, functional characterization of mutant cells in vitro may generate helpful ancillary evidence with regard to the pathogenicity of gene variants in comparison with established mutations.

  20. A New Current Mode SIMO-Type Universal Biquad Employing Multi-Output Current Conveyors (MOCCIIs

    Directory of Open Access Journals (Sweden)

    S. Du

    2009-04-01

    Full Text Available This study presents a new current-mode singleinput and multi-output (SIMO type universal biquad circuit using second generation multi-output current conveyors (MOCCII as the active components. The proposed circuit employs three MOCCIIs, two grounded capacitors and four grounded resistors, therefore offers electroning tuning possibilities. It can simultaneously realize second order low-pass, band-pass, high-pass, notch and all-pass filters. The circuit is cascadable and has low sensitivities. It provides independent control of ω0 (natural angular frequency and Q (quality factor. The influences of MOCCII parasitic elements have been analyzed and simulated using PSPICE. Experimental results including frequency responses of low-pass, high-pass, band-pass and band-stop filters, as well as frequency responses of filters with different ω0 (keeping Q invariable and different Q (keeping ω0 invariable are shown to be in agreement with theory.

  1. Current view from Alzheimer disease to type 2 diabetes mellitus.

    Science.gov (United States)

    Rasool, Mahmood; Malik, Arif; Qazi, Aamer M; Sheikh, Ishfaq A; Manan, Abdul; Shaheen, Sumaira; Qazi, Mahmood H; Chaudhary, Adeel G; Abuzenadah, Adel M; Asif, Muhammad; Alqahtani, Mohammed H; Iqbal, Zafar; Shaik, Munvar M; Gan, Siew H; Kamal, Mohammad A

    2014-04-01

    Alzheimer's disease (AD) is a neurodegenerative disorder that leads to memory problems. It has been associated with type 2 diabetes mellitus at both the molecular and biochemical level. Pancreatic cells have molecular similarities to the brain at the transcriptomic and proteomic levels. Several genes have been reported to be responsible for both AD and diabetes. Currently, no proper treatment is available but various therapeutic approaches are utilized worldwide for the management of these disorders and may be nanoparticles and herbal treatment of Bacopa monnieri will make promise for the treatment of AD in future. The formation of amyloids in neurons and the formation of amylin in pancreatic cells are potential links between these two disorders, which can be silent killers.

  2. Current-type flipped-Γ-source inverters

    DEFF Research Database (Denmark)

    Loh, Poh Chiang; Li, Ding; Blaabjerg, Frede

    2012-01-01

    Z-source inverters are innovative single-stage topologies proposed for flexible buck-boost energy conversion. To raise their gains and modulation ratios further, a number of variations have been introduced with some using magnetically coupled transformers or inductors. These variants are of inter......Z-source inverters are innovative single-stage topologies proposed for flexible buck-boost energy conversion. To raise their gains and modulation ratios further, a number of variations have been introduced with some using magnetically coupled transformers or inductors. These variants...... are of interest since they use lesser components. Their winding turns might however become too excessive for higher demanded gains. Avoiding this usual trend, a new family of current-type flipped-Γ-source inverters are proposed, whose common gain is raised by lowering, and not increasing, the winding turns...

  3. Two types of coherence resonance in an intracellular calcium oscillation system

    Science.gov (United States)

    Ma, Juan; Gao, Qingyu

    2017-09-01

    Two types of noise induced oscillations (NIOs) near Hopf bifurcation and coherence resonance (CR) have been studied analytically in a calcium system. One is NIOs with small amplitude and internal signal stochastic resonance (CR type I) occurs, and the other is noise induced spike and the regularity of which reaches a maximum at an optimal noise level (CR type II). For the first type, stochastic normal form theory is employed to analyze the signal to noise ratio of the NIOs depending on the noise intensity. For the second type, based on the independent assumption, activation time and excursion time have been split, and the sum of which reach a minimum with the variation of noise intensity. The theoretical evidence is also explained in detail. Numerical simulations show good agreements with the theoretical results. It may indicate some kind of transmit mechanism involved in stochastic calcium dynamics.

  4. Low-temperature-compatible tunneling-current-assisted scanning microwave microscope utilizing a rigid coaxial resonator

    Science.gov (United States)

    Takahashi, Hideyuki; Imai, Yoshinori; Maeda, Atsutaka

    2016-06-01

    We present a design for a tunneling-current-assisted scanning near-field microwave microscope. For stable operation at cryogenic temperatures, making a small and rigid microwave probe is important. Our coaxial resonator probe has a length of approximately 30 mm and can fit inside the 2-in. bore of a superconducting magnet. The probe design includes an insulating joint, which separates DC and microwave signals without degrading the quality factor. By applying the SMM to the imaging of an electrically inhomogeneous superconductor, we obtain the spatial distribution of the microwave response with a spatial resolution of approximately 200 nm. Furthermore, we present an analysis of our SMM probe based on a simple lumped-element circuit model along with the near-field microwave measurements of silicon wafers having different conductivities.

  5. High yield neutron generator based on a high-current gasdynamic electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Skalyga, V.; Sidorov, A. [Institute of Applied Physics of Russian Academy of Sciences, 46 Ulyanova St., Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod (UNN), 23 Gagarina St., Nizhny Novgorod (Russian Federation); Izotov, I.; Golubev, S.; Razin, S. [Institute of Applied Physics of Russian Academy of Sciences, 46 Ulyanova St., Nizhny Novgorod (Russian Federation); Strelkov, A. [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Tarvainen, O.; Koivisto, H.; Kalvas, T. [Department of Physics, University of Jyväskylä, Jyväskylä (Finland)

    2015-09-07

    In present paper, an approach for high yield compact D-D neutron generator based on a high current gasdynamic electron cyclotron resonance ion source is suggested. Results on dense pulsed deuteron beam production with current up to 500 mA and current density up to 750 mA/cm{sup 2} are demonstrated. Neutron yield from D{sub 2}O and TiD{sub 2} targets was measured in case of its bombardment by pulsed 300 mA D{sup +} beam with 45 keV energy. Neutron yield density at target surface of 10{sup 9} s{sup −1} cm{sup −2} was detected with a system of two {sup 3}He proportional counters. Estimations based on obtained experimental results show that neutron yield from a high quality TiD{sub 2} target bombarded by D{sup +} beam demonstrated in present work accelerated to 100 keV could reach 6 × 10{sup 10} s{sup −1} cm{sup −2}. It is discussed that compact neutron generator with such characteristics could be perspective for a number of applications like boron neutron capture therapy, security systems based on neutron scanning, and neutronography.

  6. Laboratory modelling of resonant wave-current interaction in the vicinity wind farm masts

    Science.gov (United States)

    Gunnoo, Hans; Abcha, Nizar; Garcia-Hermosa, Maria-Isabel; Ezersky, Alexander

    2015-04-01

    In the nearest future, by 2020, about 4% of electricity in Europe will be supplied by sea stations operating from renewable sources: ocean thermal energy, wave and tidal energy, wind farms. By now the wind stations located in the coastal zone, provide the most part of electricity in different European countries. Meanwhile, effects of wind farms on the environment are not sufficiently studied. We report results of laboratory simulations aimed at investigation of hydrodynamic fields arising in the vicinity of wind farm masts under the action of currents and surface waves. The main attention is paid to modeling the resonance effects when the amplitude of velocity pulsations in the vicinity of the masts under the joint action of currents and harmonic waves demonstrate significant growth. This resonance can lead to an increase in Reynolds stress on the bottom, intensification of sediment transport and sound generation. The experiments are performed in the 17 meters hydrodynamical channel of laboratory Morphodynamique Continentale et Côtière UMR CNRS 6143. Mast are modeled by vertical cylinder placed in a steady flow. Behind the cylinder turbulent Karman vortex street occurs. Results are obtained in interval of Reynolds numbers Re=103 - 104(Re=Ud/v, where U is the velocity of the flow, d is diameter of the cylinder, ν is cinematic viscosity). Harmonic surface waves of small amplitude propagating upstream are excited by computer controlled wave maker. In the absence of surface waves, turbulent Karman street with averaged frequency f is observed. It is revealed experimentally that harmonic surface waves with a frequencies closed to 2f can synchronize vortex shedding and increase the amplitude of velocity fluctuations in the wake of the cylinder. Map of regimes is found on the parameter plane amplitude of the surface wave - wave frequency. In order to distinguish the synchronization regimes, we defined phase of oscillations using the Hilbert transform technique. We

  7. Autonomous control of inverter-interfaced Distributed Generation units for harmonic current filtering and resonance damping in an islanded microgrid

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2012-01-01

    Harmonic current filtering and resonance damping have become important concerns on the control of an islanded microgrids. To address these challenges, this paper proposes a control method of inverter-interfaced Distributed Generation (DG) units, which can autonomously share harmonic currents and ...

  8. Reduction of diesel engine exhaust noise in the petroleum mining industry. [by resonator type diffuser

    Science.gov (United States)

    Marinov, T.

    1974-01-01

    An important noise source in a drilling plant is Diesel engine exhaust. In order to reduce this noise, a reactive silencer of the derivative resonator type was proposed, calculated from the acoustic and design point of view and applied. As a result of applying such a silencer on the exhaust conduit of a Diesel engine the noise level dropped down to 18 db.

  9. Squeezing and entanglement in doubly resonant, type II, second-harmonic generation

    DEFF Research Database (Denmark)

    Andersen, Ulrik Lund; Buchhave, Preben

    2003-01-01

    We investigate, theoretically, the generation of bright and vacuum-squeezed light as well as entanglement in intracavity, type II, phase-matched second-harmonic generation. The cavity in which the crystal is embedded is resonant at the fundamental frequency but not at the second-harmonic frequenc...

  10. Optically detected magnetic resonance study of a type-II GaAs/AlAs multiple quantum well

    Science.gov (United States)

    van Kesteren, H. W.; Cosman, E. C.; Greidanus, F. J. A. M.; Dawson, P.; Moore, K. J.; Foxon, C. T.

    1988-07-01

    In a type-II GaAs/AlAs multiple quantum well three optically detected magnetic resonance lines and two level anticrossings were observed. Two of the resonance lines and the two level anticrossings are in agreement with the electronic level scheme of the heavy-hole exciton. The third resonance line is in accordance with a magnetic spin resonance of an unbound electron. These optically detected magnetic resonance measurements open up the possibility to obtain detailed information about the excitons in and the band structure of type-II quantum wells.

  11. First Measurement of the Neutral Current Excitation of the Delta Resonance on a Proton Target

    CERN Document Server

    Androic, D; Arvieux, J; Bailey, S L; Beck, D H; Beise, E J; Benesch, J; Benmokhtar, F; Bimbot, L; Birchall, J; Bosted, P; Breuer, H; Capuano, C L; Chao, Y -C; Coppens, A; Davis, C A; Ellis, C; Flores, G; Franklin, G; Furget, C; Gaskell, D; Grames, J; Gericke, M T W; Guillard, G; Hansknecht, J; Horn, T; Jones, M K; King, P M; Korsch, W; Kox, S; Lee, L; Liu, J; Lung, A; Mammei, J; Martin, J W; McKeown, R D; Micherdzinska, A; Mihovilovic, M; Mkrtchyan, H; Muether, M; Page, S A; Papavassiliou, V; Pate, S F; Phillips, S K; Pillot, P; Pitt, M L; Poelker, M; Quinn, B; Ramsay, W D; Real, J -S; Roche, J; Roos, P; Schaub, J; Seva, T; Simicevic, N; Smith, G R; Spayde, D T; Stutzman, M; Suleiman, R; Tadevosyan, V; van Oers, W T H; Versteegen, M; Voutier, E; Vulcan, W; Wells, S P; Williamson, S E; Wood, S A

    2012-01-01

    The parity-violating asymmetry arising from inelastic electron-nucleon scattering at backward angle (~95 degrees) near the Delta(1232) resonance has been measured using a hydrogen target. From this asymmetry, we extracted the axial transition form factor G^A_{N\\Delta}, a function of the axial Adler form factors C^A_i. Though G^A_{N\\Delta} has been previously studied using charged current reactions, this is the first measurement of the weak neutral current excitation of the Delta using a proton target. For Q^2 = 0.34 (GeV/c)^2 and W = 1.18 GeV, the asymmetry was measured to be -33.4 \\pm (5.3)_{stat} \\pm (5.1)_{sys} ppm. The value of G^A_{N\\Delta} determined from the hydrogen asymmetry was -0.05 \\pm (0.35)_{stat} \\pm (0.34)_{sys} \\pm (0.06)_{theory}. These findings agree within errors with theoretical predictions for both the total asymmetry and the form factor. In addition to the hydrogen measurement, the asymmetry was measured at the same kinematics using a deuterium target. The asymmetry for deuterium was de...

  12. A new type of HTc superconducting film comb-shape resonator for radio frequency superconducting quantum interference devices

    Institute of Scientific and Technical Information of China (English)

    MAO Hai-yan; WANG Fu-ren; MENG Shu-chao; MAO Bo; LI Zhuang-zhi; NIE Rui-juan; LIU Xin-yuan; DAI Yuan-dong

    2006-01-01

    A new type of HTc superconducting film combshape resonator for radio frequency superconducting quantum interference devices (RF SQUID) has been designed.This new type of superconducting film comb-shape resonator is formed by a foursquare microstrip line without a flux concentrator.The range of the center frequency of this type of resonator varies from 800 MHz to 1300 MHz by changing the length of the teeth.In this paper,we report on simulating the relationship of the value of the center frequency and the length of the teeth,and testing the noise of HTc RF SQUID coupling this comb-shape resonator.

  13. Experimental characterization of cantilever-type piezoelectric generator operating at resonance for vibration energy harvesting

    Science.gov (United States)

    Montanini, Roberto; Quattrocchi, Antonino

    2016-06-01

    A cantilever-type resonant piezoelectric generator (RPG) has been designed by gluing a PZT patch working in d31 mode onto a glass fibre reinforced composite cantilever beam with a discrete mass applied on its free end. The electrical and dynamic behaviour of the RPG prototype has been investigated by carrying out laboratory tests aimed to assess the effect of definite design parameters, specifically the electric resistance load and the excitation frequency. Results showed that an optimum resistance load exists, at which power generation is maximized. Moreover, it has been showed that power generation is strongly influenced by the vibration frequency highlighting that, at resonance, output power can be increased by more than one order of magnitude. Possible applications include inertial resonant harvester for energy recovery from vibrating machines, sea waves or wind flux and self-powering of wireless sensor nodes.

  14. Experimental characterization of cantilever-type piezoelectric generator operating at resonance for vibration energy harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Montanini, Roberto, E-mail: rmontanini@unime.it; Quattrocchi, Antonino, E-mail: aquattrocchi@unime.it [University of Messina, Dept. of Engineering, Contrada di Dio, Messina (Italy)

    2016-06-28

    A cantilever-type resonant piezoelectric generator (RPG) has been designed by gluing a PZT patch working in d{sub 31} mode onto a glass fibre reinforced composite cantilever beam with a discrete mass applied on its free end. The electrical and dynamic behaviour of the RPG prototype has been investigated by carrying out laboratory tests aimed to assess the effect of definite design parameters, specifically the electric resistance load and the excitation frequency. Results showed that an optimum resistance load exists, at which power generation is maximized. Moreover, it has been showed that power generation is strongly influenced by the vibration frequency highlighting that, at resonance, output power can be increased by more than one order of magnitude. Possible applications include inertial resonant harvester for energy recovery from vibrating machines, sea waves or wind flux and self-powering of wireless sensor nodes.

  15. [Comments on current guidelines of type 2 diabetes mellitus treatment].

    Science.gov (United States)

    Martinka, Emil

    In an effort to facilitate the widest possible application of recent findings in diabetology and the related medical fields, with regard to characteristics of medicines and current possibilities of using modern procedures, but also to their limitations due to the financial capacities of health insurance companies, SDS innovates its therapeutic recommendations for the treatment of diabetes mellitus on a regular basis. The most recent recommendations were issued by SDS in August 2016. The review discusses and describes several factors which the authors considered during their preparation: (1) Compliance with the findings of evidence-based medicine, compliance with reference recommendations (therapeutic recommendations ADA/EASD), compliance with summary characteristics of active substances in the treatment of diabetes mellitus and approved possibilities of their use, and compliance with indica-tive restrictions (IO) which define medical and economic conditions for health insurance covered treatment. (2) Certain departure from the "glucocentric" approach to therapy, in favour of the approach preferring the selection of drugs based on clinical characteristics of the patient and proven benefits/risks of individual drugs (3) Preference of groups as well as individual active substances within groups based on evidence medicine regarding the individual active substances for specific patient groups. (4) Emphasis on individualization of goals for glycemic control (5) Emphasis on the right classification of diabetes mellitus as the basic condition for the selection of an optimum thera-peutic procedure, and (6) Emphasis on education and overcoming of clinical inertia, and patient medication adherence and medication "literacy" as the basic condition for successful therapy. The discussion also considers the outcomes of the most recent studies including of the studies focusing on empagliflozin and liraglutide, as well as recent modifications of the therapeutic recommendations of

  16. Magnetic resonance imaging of the chest: current and new applications, with an emphasis on pulmonology

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marcel Koenigkam; Mauad, Fernando Marum, E-mail: marcelk46@yahoo.com.b [Universidade de Sao Paulo (HC/FMRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina. Hospital das Clinicas; Elias Junior, Jorge; Muglia, Valdair Francisco [Universidade de Sao Paulo (FMRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina. Secao de Radiologia

    2011-03-15

    The objective of the present review study was to present the principal applications of magnetic resonance imaging (MRI) of the chest, including the description of new techniques. Over the past decade, this method has evolved considerably because of the development of new equipment, including the simultaneous interconnection of phased-array multiple radiofrequency receiver coils and remote control of the table movement, in addition to faster techniques of image acquisition, such as parallel imaging and partial Fourier acquisitions, as well as the introduction of new contrast agents. All of these advances have allowed MRI to gain ground in the study of various pathologies of the chest, including lung diseases. Currently, MRI is considered the modality of choice for the evaluation of lesions in the mediastinum and in the chest wall, as well as of superior sulcus tumors. However, it can also facilitate the diagnosis of lung, pleural, and cardiac diseases, as well as of those related to the pulmonary vasculature. Pulmonary MRI angiography can be used in order to evaluate various pulmonary vascular diseases, and it has played an ever greater role in the study of thromboembolism. Because cardiac MRI allows morphological and functional assessment in the same test, it has also become part of the clinical routine in the evaluation of various cardiac diseases. Finally, the role of MRI has been extended to the identification and characterization of pulmonary nodules, the evaluation of airway diseases, and the characterization of pleural effusion. (author)

  17. Current Role and Future Perspectives of Magnetic Resonance Spectroscopy in Radiation Oncology for Prostate Cancer

    Directory of Open Access Journals (Sweden)

    Aleksandra Zapotoczna

    2007-06-01

    Full Text Available Prostatic neoplasms are not uniformly distributed within the prostate volume. With recent developments in three-dimensional intensity-modulated and imageguided radiation therapy, it is possible to treat different volumes within the prostate to different thresholds of doses. This approach has the potential to adapt the dose to the biologic aggressiveness of various clusters of tumor cells within the gland. The definition of tumor burden volume in prostate cancer can be facilitated by the use of magnetic resonance spectroscopy (MRS. The increasing sensitivity and specificity of MRS to the prostate is causing new interest in its potential role in the definition of target subvolumes at higher risk of failure following radical radiotherapy. Prostate MRS might also play a role as a noninvasive predictive factor for tumor response and treatment outcome. We review the use of MRS in radiation therapy for prostate cancer by evaluating its accuracy in the classification of aggressive cancer regions and target definition; its current role in the radiotherapy planning process, with special interest in technical issues behind the successful inclusion of MRS in clinical use; and available early experiences as a prognostic tool.

  18. Magnetic resonance imaging biomarkers in patients with progressive ataxia: current status and future direction.

    Science.gov (United States)

    Currie, Stuart; Hadjivassiliou, Marios; Craven, Ian J; Wilkinson, Iain D; Griffiths, Paul D; Hoggard, Nigel

    2013-04-01

    A diagnostic challenge commonly encountered in neurology is that of an adult patient presenting with ataxia. The differential is vast and clinical assessment alone may not be sufficient due to considerable overlap between different causes of ataxia. Magnetic resonance (MR)-based biomarkers such as voxel-based morphometry, MR spectroscopy, diffusion-weighted and diffusion-tensor imaging and functional MR imaging are gaining great attention for their potential as indicators of disease. A number of studies have reported correlation with clinical severity and underlying pathophysiology, and in some cases, MR imaging has been shown to allow differentiation of conditions causing ataxia. However, despite recent advances, their sensitivity and specificity vary. In addition, questions remain over their validity and reproducibility, especially when applied in routine clinical practice. This article extensively reviews the current literature regarding MR-based biomarkers for the patient with predominantly adult-onset ataxia. Imaging features characteristic of a particular ataxia are provided and features differentiating ataxia groups and subgroups are discussed. Finally, discussion will turn to the feasibility of applying these biomarkers in routine clinical practice.

  19. Current density distributions and sputter marks in electron cyclotron resonance ion sources.

    Science.gov (United States)

    Panitzsch, Lauri; Peleikis, Thies; Böttcher, Stephan; Stalder, Michael; Wimmer-Schweingruber, Robert F

    2013-01-01

    Most electron cyclotron resonance ion sources use hexapolar magnetic fields for the radial confinement of the plasma. The geometry of this magnetic structure is then--induced by charged particles--mapped onto the inner side of the plasma electrode via sputtering and deposition. The resulting structures usually show two different patterns: a sharp triangular one in the central region which in some cases is even sputtered deep into the material (referred to as thin groove or sharp structure), and a blurred but still triangular-like one in the surroundings (referred to as broad halo). Therefore, both patterns seem to have different sources. To investigate their origins we replaced the standard plasma electrode by a custom-built plasma electrode acting as a planar, multi-segment current-detector. For different biased disc voltages, detector positions, and source biases (referred to the detector) we measured the electrical current density distributions in the plane of the plasma electrode. The results show a strong and sharply confined electron population with triangular shape surrounded by less intense and spatially less confined ions. Observed sputter- and deposition marks are related to the analysis of the results. Our measurements suggest that the two different patterns (thin and broad) indeed originate from different particle populations. The thin structures seem to be caused by the hot electron population while the broad marks seem to stem from the medium to highly charged ions. In this paper we present our measurements together with theoretical considerations and substantiate the conclusions drawn above. The validity of these results is also discussed.

  20. Low-Cost Digital Implementation of Proportional-Resonant Current Controllers for PV Inverter Applications Using Delta Operator

    DEFF Research Database (Denmark)

    Será, Dezsö; Kerekes, Tamas; Lungeanu, Marian

    2005-01-01

    of the P+Resonant controller with selective harmonic compensation on a low-cost fixed-point DSP. The resonant part of the P+R has been implemented as a second order filter based on Delta operator. The current controller, together with harmonic compensation for the 3rd, 5th, and 7th harmonics has been......The performances of the P+Resonant controller in case of current control for a single phase grid connected inverter have been proved to be superior to the PI controller, since it is able to remove the phase error of the control at the fundamental frequency of the grid. It offers also...... the possibility of selective harmonic compensation. However, in case of digital implementation on a low-cost fixedpoint DSP, the limited computational power and the limited numerical representation precision can restrict the utilization of it. The present paper proposes a different way of digital implementation...

  1. Overview of current multiparametric magnetic resonance imaging approach in the diagnosis and staging of prostate cancer

    Directory of Open Access Journals (Sweden)

    Hasan Aydın

    2015-04-01

    Full Text Available This article is primarily based on the utility and validity of multiparametric magnetic resonance imaging in the diagnosis and staging of prostate gland tumors. Multiparametric magnetic resonance imaging is an emerging, useful approach for evaluating and detecting prostate cancers. It also aids in the management of a tumor and improve the care and follow-up of patients.

  2. Magnetic resonance imaging in neuropsychiatric systemic lupus erythematosus: current state of the art and novel approaches.

    Science.gov (United States)

    Postal, M; Lapa, A Tamires; Reis, F; Rittner, L; Appenzeller, S

    2017-04-01

    Systemic lupus erythematosus is a chronic, inflammatory, immune-mediated disease affecting 0.1% of the general population. Neuropsychiatric manifestations in systemic lupus erythematosus have been more frequently recognized and reported in recent years, occurring in up to 75% of patients during the disease course. Magnetic resonance imaging is known to be a useful tool for the detection of structural brain abnormalities in neuropsychiatric systemic lupus erythematosus patients because of the excellent soft-tissue contrast observed with MRI and the ability to acquire multiplanar images. In addition to conventional magnetic resonance imaging techniques to evaluate the presence of atrophy and white matter lesions, several different magnetic resonance imaging techniques have been used to identify microstructural or functional abnormalities. This review will highlight different magnetic resonance imaging techniques, including the advanced magnetic resonance imaging methods used to determine central nervous system involvement in systemic lupus erythematosus.

  3. Active damping of LLCL-filter resonance based on LC-trap voltage and capacitor current feedback

    DEFF Research Database (Denmark)

    Huang, Min; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    . In this paper, different feedback coefficients like the proportional, derivative, integral, high pass and low pass feedback coefficients of the filter capacitor current and the LC-trap circuit voltage are investigated for damping the filter resonance. Active damping methods are analyzed by using the concept...

  4. Unified analytical expressions for calculating resonant frequencies, transimpedances, and equivalent input noise current densities of tuned receiver front ends

    DEFF Research Database (Denmark)

    Liu, Qing Zhong

    1992-01-01

    Unified analytical expressions have been derived for calculating the resonant frequencies, transimpedance and equivalent input noise current densities of the four most widely used tuned optical receiver front ends built with FETs and p-i-n diodes. A more accurate FET model has been used to improve...

  5. Autonomous Control of Inverter-Interfaced Distributed Generation Units for Harmonic Current Filtering and Resonance Damping in an Islanded Microgrid

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2014-01-01

    Harmonic current filtering and resonance damping have become important concerns in the operation and control of the islanded microgrids. To address these challenges, this paper proposes a control method for the inverter-interfaced Distributed Generation (DG) units, which can autonomously share th...

  6. Study of wavelet transform type high-current transformer

    Institute of Scientific and Technical Information of China (English)

    卢文科; 朱长纯; 刘君华; 张建军

    2002-01-01

    The wavelet transformation is applied to the high-current transformer.The high-current transformer elaborated in the paper is mainly applied to the measurement of AC/DC high-current.The principle of the transformer is the Hall direct-measurement principle.The transformer has the following three characteristics:firstly, the effect of the remnant field of the iron core on the measurement is decreased;secondly,because the temperature compensation is adopted,the transformer has good temperature charactreristic;thirdly,be-cause the wavelet transfomation technology is adopted,the transformer has the capacity of good antijanming.

  7. Magnetic resonance imaging segmentation techniques using batch-type learning vector quantization algorithms.

    Science.gov (United States)

    Yang, Miin-Shen; Lin, Karen Chia-Ren; Liu, Hsiu-Chih; Lirng, Jiing-Feng

    2007-02-01

    In this article, we propose batch-type learning vector quantization (LVQ) segmentation techniques for the magnetic resonance (MR) images. Magnetic resonance imaging (MRI) segmentation is an important technique to differentiate abnormal and normal tissues in MR image data. The proposed LVQ segmentation techniques are compared with the generalized Kohonen's competitive learning (GKCL) methods, which were proposed by Lin et al. [Magn Reson Imaging 21 (2003) 863-870]. Three MRI data sets of real cases are used in this article. The first case is from a 2-year-old girl who was diagnosed with retinoblastoma in her left eye. The second case is from a 55-year-old woman who developed complete left side oculomotor palsy immediately after a motor vehicle accident. The third case is from an 84-year-old man who was diagnosed with Alzheimer disease (AD). Our comparisons are based on sensitivity of algorithm parameters, the quality of MRI segmentation with the contrast-to-noise ratio and the accuracy of the region of interest tissue. Overall, the segmentation results from batch-type LVQ algorithms present good accuracy and quality of the segmentation images, and also flexibility of algorithm parameters in all the comparison consequences. The results support that the proposed batch-type LVQ algorithms are better than the previous GKCL algorithms. Specifically, the proposed fuzzy-soft LVQ algorithm works well in segmenting AD MRI data set to accurately measure the hippocampus volume in AD MR images.

  8. Seasonal affective disorder, winter type: current insights and treatment options

    National Research Council Canada - National Science Library

    Meesters Y; Gordijn MCM

    2016-01-01

    ...., Groningen, the Netherlands Abstract: Seasonal affective disorder (SAD), winter type, is a seasonal pattern of recurrent major depressive episodes most commonly occurring in autumn or winter and remitting in spring/summer...

  9. Insect-inspired wing actuation structures based on ring-type resonators

    Science.gov (United States)

    Bolsman, Caspar T.; Goosen, Johannes F. L.; van Keulen, Fred

    2008-03-01

    In this paper, we illustrate and study the opportunities of resonant ring type structures as wing actuation mechanisms for a flapping wing Micro Air Vehicle (MAV). Various design alternatives are presented and studied based on computational and physical models. Insects provide an excellent source of inspiration for the development of the wing actuation mechanisms for flapping wing MAVs. The insect thorax is a structure which in essence provides a mechanism to couple the wing muscles to the wings while offering weight reduction through application of resonance, using tailored elasticity. The resonant properties of the thorax are a very effective way to reducing the power expenditure of wing movement. The wing movement itself is fairly complex and is guided by a set of control muscles and thoracic structures which are present in proximity of the wing root. The development of flapping wing MAVs requires a move away from classical structures and actuators. The use of gears and rotational electric motors is hard to justify at the small scale. Resonant structures provide a large design freedom whilst also providing various options for actuation. The move away from deterministic mechanisms offers possibilities for mass reduction.

  10. Vibration Mode Observation of Piezoelectric Disk-type Resonator by High Frequency Laser Doppler Vibrometer

    Science.gov (United States)

    Matsumura, Takeshi; Esashi, Masayoshi; Harada, Hiroshi; Tanaka, Shuji

    For future mobile phones based on cognitive radio technology, a compact multi-band RF front-end architecture is strongly required and an integrated multi-band RF filter bank is a key component in it. Contour-mode resonators are receiving increased attention for a multi-band filter solution, because its resonant frequency is mainly determined by its size and shape, which are defined by lithography. However, spurious responses including flexural vibration are also excited due to its thin structure. To improve resonator performance and suppress spurious modes, visual observation with a laser probe system is very effective. In this paper, we have prototyped a mechanically-coupled disk-array filter, which consists of a Si disk and 2 disk-type resonators of higher-order wine-glass mode, and observed its vibration modes using a high-frequency laser-Doppler vibrometer (UHF-120, Polytec, Inc.). As a result, it was confirmed that higher order wine-glass mode vibration included a compound displacement, and that its out-of-plane vibration amplitude was much smaller than other flexural spurious modes. The observed vibration modes were compared with FEM (Finite Element Method) simulation results. In addition, it was also confirmed that the fabrication error, e.g. miss-alignment, induced asymmetric vibration.

  11. Modeling and Analysis of Resonance in LCL-Type Grid-Connected Inverters under Different Control Schemes

    Directory of Open Access Journals (Sweden)

    Yanxue Yu

    2017-01-01

    Full Text Available As a basic building block in power systems, the three-phase voltage-source inverter (VSI connects the distributed energy to the grid. For the inductor-capacitor-inductor (LCL-filter three-phase VSI, according to different current sampling position and different reference frame, there mainly exist four control schemes. Different control schemes present different impedance characteristics in their corresponding determined frequency range. To analyze the existing resonance phenomena due to the variation of grid impedances, the sequence impedance models of LCL-type grid-connected three-phase inverters under different control schemes are presented using the harmonic linearization method. The impedance-based stability analysis approach is then applied to compare the relative stability issues due to the impedance differences at some frequencies and to choose the best control scheme and the better controller parameters regulating method for the LCL-type three-phase VSI. The simulation and experiments both validate the resonance analysis results.

  12. Circular periodic orbits, resonance capture and inclination excitation during type II migration

    Science.gov (United States)

    Antoniadou, K. I.; Voyatzis, G.

    2017-03-01

    We consider planetary systems evolving under the effect of a Stokes-type dissipative force mimicking the outcome of a type II migration process. As inward migration proceeds and the planets follow the circular family (they start on circular orbits) and even though they are initially almost coplanar, resonance capture can be realized. Then, at the vertical critical orbits (VCOs), that the circular family possesses, the inclination excitation can abruptly take place. The planets are now guided by the spatial elliptic families, which bifurcate from those critical orbits. We herein, perform a direct link of mutually inclined stable planetary systems on circular orbits trapped in mean-motion resonance (MMR) with the existence of VCOs of high values of multiplicity. It is shown that the more the multiplicity of the periodic orbits of the circular family increases, the more VCOs (corresponding to more MMRs) appear. In this way, we can provide a justification for the existence of resonant planets on circular orbits, which could, even further to that, evolve stably if they were mutually inclined.

  13. Randomly Distributed Fabry-Pérot-type Metal Nanowire Resonators and Their Lasing Action

    Science.gov (United States)

    Kwon, Kyungmok; Jung, Youngho; Kim, Minkyung; Shim, Jaeho; Yu, Kyoungsik

    2016-04-01

    Optical feedback mechanisms are often obtained from well-defined resonator structures fabricated by top-down processes. Here, we demonstrate that two-dimensional networks of metallic nanowires dispersed on the semiconductor slab can provide strong in-plane optical feedback and, thus, form randomly-distributed Fabry-Pérot-type resonators that can achieve multi- or single-mode lasing action in the near infrared wavelengths. Albeit with their subwavelength-scale cross-sections and uncontrolled inter-nanowire distances, a cluster of nearly parallel metal nanowires acts as an effective in-situ reflector for the semiconductor-metal slab waveguide modes for coherent optical feedback in the lateral direction. Fabry-Pérot type resonance can be readily developed by a pair of such clusters coincidentally formed in the solution-processed random nanowire network. Our low-cost and large-area approach for opportunistic random cavity formation would open a new pathway for integrated planar light sources for low-coherence imaging and sensing applications.

  14. Seasonal affective disorder, winter type : current insights and treatment options

    NARCIS (Netherlands)

    Meesters, Ybe; Gordijn, Margaretha

    2016-01-01

    Seasonal affective disorder (SAD), winter type, is a seasonal pattern of recurrent major depressive episodes most commonly occurring in autumn or winter and remitting in spring/summer. The syndrome has been well-known for more than three decades, with light treatment being the treatment of first

  15. Membrane-type resonator as an effective miniaturized tuned vibration mass damper

    Directory of Open Access Journals (Sweden)

    Liang Sun

    2016-08-01

    Full Text Available Damping of low frequency vibration by lightweight and compact devices has been a serious challenge in various areas of engineering science. Here we report the experimental realization of a type of miniature low frequency vibration dampers based on decorated membrane resonators. At frequency around 150 Hz, two dampers, each with outer dimensions of 28 mm in diameter and 5 mm in height, and a total mass of 1.78 g which is less than 0.6% of the host structure (a nearly free-standing aluminum beam, can reduce its vibrational amplitude by a factor of 1400, or limit its maximum resonance quality factor to 18. Furthermore, the conceptual design of the dampers lays the foundation and demonstrates the potential of further miniaturization of low frequency dampers.

  16. Membrane-type resonator as an effective miniaturized tuned vibration mass damper

    Science.gov (United States)

    Sun, Liang; Au-Yeung, Ka Yan; Yang, Min; Tang, Suet To; Yang, Zhiyu; Sheng, Ping

    2016-08-01

    Damping of low frequency vibration by lightweight and compact devices has been a serious challenge in various areas of engineering science. Here we report the experimental realization of a type of miniature low frequency vibration dampers based on decorated membrane resonators. At frequency around 150 Hz, two dampers, each with outer dimensions of 28 mm in diameter and 5 mm in height, and a total mass of 1.78 g which is less than 0.6% of the host structure (a nearly free-standing aluminum beam), can reduce its vibrational amplitude by a factor of 1400, or limit its maximum resonance quality factor to 18. Furthermore, the conceptual design of the dampers lays the foundation and demonstrates the potential of further miniaturization of low frequency dampers.

  17. Pheochromocytoma associated with neurofibromatosis type 1: concepts and current trends

    OpenAIRE

    Vogiaki Sophia; Korkolis Dimitris; Aggeli Chrysanthi; Zagouri Flora; Vasiliadis George K; Zografos George N; Pagoni Matina K; Kaltsas Gregory; Piaditis George

    2010-01-01

    Abstract Background Neurofibromatosis Type 1(NF-1) has autosomal dominant inheritance with complete penetrance, variable expression and a high rate of new mutation. Pheochromocytoma occurs in 0.1%-5.7% of patients with NF-1. Case presentation We present the case of a 37-year-old patient with laparoscopically resected pheochromocytoma. He was investigated for hypertension, flushing and ectopic heart beat. Abdominal CT and MRI revealed a mass measuring 8 × 4 cm in the right adrenal gland. The d...

  18. Characteristics of electron cyclotron resonance plasma formed by lower hybrid current drive grill antenna

    Indian Academy of Sciences (India)

    P K Sharma; S L Rao; K Mishra; R G Trivedi; D Bora

    2008-03-01

    A 3.7 GHz system, which is meant for LHCD experiments on ADITYA tokamak, is used for producing ECR discharge. The ECR discharge is produced by setting the appropriate resonance magnetic field of 0.13 T, with hydrogen at a fill pressure of about 5 × 10-5 Torr. The RF powe r, up to 10 kW (of which ∼ 50% is reflected back), with a typical pulse length of 50 ms, is injected into the vacuum chamber of the ADITYA tokamak by a LHCD grill antenna and is used for plasma formation. The average coupled RF power density (the RF power/a typical volume of the plasma) is estimated to be ∼ 5 kW/m3. When the ECR appears inside the tokamak chamber for the given pumping frequency ( = 3.7 GHz) a plasma with a density () ∼ 4 × 1016 m-3 and electron temperature ∼ 8 eV is produced. The density and temperature during the RF pulse are measured by sets of Langmuir probes, located toroidally, on either side of the antenna. signals are also monitored to detect ionization. An estimate of density and temperature based on simple theoretical calculation agrees well with our experimental measurements. The plasma produced by the above mechanism is further used to characterize the ECR-assisted low voltage Ohmic start-up discharges. During this part of the experiments, Ohmic plasma is formed using capacitor banks. The plasma loop voltage is gradually decreased, till the discharge ceases to form. The same is repeated in the presence of ECR-formed plasma (RF pre-ionization), formed 10 ms prior to the loop voltage. We have observed that (with LHCD-induced) ECR-assisted Ohmic start-up discharges is reliably and repeatedly obtained with reduced loop voltage requirement and breakdown time decreases substantially. The current ramp-up rates also decrease with reduced loop voltage operation. These studies established that ECR plasma formed with LHCD system exhibits similar characteristics as reported earlier by dedicated ECR systems. This experiment also addresses the issue of whether ECR plasma

  19. Heat Generation by Electrical Current in Quantum Dot System with Fano Resonance

    Institute of Scientific and Technical Information of China (English)

    陈桥; 许迈昌; 屈喜龙

    2012-01-01

    We study the heat generation in quantum dot system with Fano resonance by nonequilibrium Green's functions method. The Fano resonance influences the heat generation significantly. As increases, the heat generation decreases gradually. From the study of Q-eV curves, we llnd that the linewidth function F has huge influence on the heat generation. The Q-eV curves display obvious steps when the linewidth function is small. However, these steps disappear with F increasing. As the source-drain bias eV increases, the Q-eVg curves also display interesting behaviors.

  20. Antiferromagentic resonance detected by direct current voltages in MnF{sub 2}/Pt bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Philipp, E-mail: philipp.ross.13@ucl.ac.uk [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Schreier, Michael, E-mail: michael.schreier@wmi.badw.de; Lotze, Johannes [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Physik-Department, Technische Universität München, Garching (Germany); Huebl, Hans; Goennenwein, Sebastian T. B. [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Nanosystems Initiative Munich, Munich (Germany); Gross, Rudolf [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Physik-Department, Technische Universität München, Garching (Germany); Nanosystems Initiative Munich, Munich (Germany)

    2015-12-21

    We performed coplanar waveguide-based broadband ferromagnetic resonance experiments on the antiferromagnetic insulator MnF{sub 2}, while simultaneously recording the DC voltage arising in a thin platinum film deposited onto the MnF{sub 2}. The antiferromagnetic resonance is clearly reflected in both the transmission through the waveguide as well as the DC voltage in the Pt strip. The DC voltage remains largely unaffected by field reversal and thus presumably stems from microwave rectification and/or heating effects. However, we identify a small magnetic field orientation dependent contribution, compatible with antiferromagnetic spin pumping theory.

  1. The Inclusive Production of the Meson Resonances in Neutrino Charged Current (cc) Interactions

    Science.gov (United States)

    Polyarush, A. Yu.

    2015-03-01

    The inclusive production of the meson resonances ρ0(770), f0(980), f2(1270), K*+(892) in neutrino-nucleon interactions has been studied with the NOMAD detector. For the first time the f0(980) meson is observed in neutrino interactions. The presence of f2(1270) in the neutrino interactions is reliably established. The average multiplicity of these three resonances is measured as a function of several kinematic variables. The experimental results are compared to the multiplicities obtained from a simulation based on the Lund model. Matrix element of spin density matrix for K*+(892) meson have been measured.

  2. Adaptive rotor current control for wind-turbine driven DFIG using resonant controllers in a rotor rotating reference frame

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper proposes an adaptive rotor current controller for doubly-fed induction generator (DFIG), which consists of a proportional (P) controller and two harmonic resonant (R) controllers implemented in the rotor rotating reference frame. The two resonant controllers are tuned at slip frequencies ωslip+ and ωslip-, respectively. As a result, the positive- and negative-sequence components of the rotor current are fully regulated by the PR controller without involving the positive- and negative-sequence decomposition, which in effect improves the fault ride-through (FRT) capability of the DFIG-based wind power generation system during the period of large transient grid voltage unbalance. Correctness of the theoretical analysis and feasibility of the proposed unbalanced control scheme are validated by simulation on a 1.5-MW DFIG wind power generation system.

  3. Unified analytical expressions for calculating resonant frequencies, transimpedances, and equivalent input noise current densities of tuned receiver front ends

    OpenAIRE

    1992-01-01

    Unified analytical expressions have been derived for calculating the resonant frequencies, transimpedance and equivalent input noise current densities of the four most widely used tuned optical receiver front ends built with FETs and p-i-n diodes. A more accurate FET model has been used to improve the accuracy of the analysis. The Miller capacitance has been taken into account, and its impact on the performances of the tuned front ends has been demonstrated. The accuracy of the expressions ha...

  4. MUSIC in triple-resonance experiments: amino acid type-selective (1)H-(15)N correlations

    Science.gov (United States)

    Schubert; Smalla; Schmieder; Oschkinat

    1999-11-01

    Amino acid type-selective triple-resonance experiments can be of great help for the assignment of protein spectra, since they help to remove ambiguities in either manual or automated assignment procedures. Here, modified triple-resonance experiments that yield amino acid type-selective (1)H-(15)N correlations are presented. They are based on novel coherence transfer schemes, the MUSIC pulse sequence elements, that replace the initial INEPT transfer and are selective for XH(2) or XH(3) (X can be (15)N or (13)C). The desired amino acid type is thereby selected based on the topology of the side chain. Experiments for Gly (G-HSQC); Ala (A-HSQC); Thr, Val, Ile, and Ala (TAVI-HSQC); Thr and Ala (TA-HSQC), as well as Asn and Gln (N-HSQC and QN-HSQC), are described. The new experiments are recorded as two-dimensional experiments and therefore need only small amounts of spectrometer time. The performance of the experiments is demonstrated with the application to two protein domains. Copyright 1999 Academic Press.

  5. Millimeter-wave FEL-oscillator with a new type Bragg resonator: advantages in efficiency and selectivity

    CERN Document Server

    Ginzburg, N S; Kaminsky, A K; Peskov, N Yu; Sedykh, S N; Sergeev, A P

    2000-01-01

    An FEL-oscillator with a new type of Bragg resonator was realized on the basis of linac LIU-3000 (JINR, Dubna) (0.8 MeV/200 A/200 ns). This resonator consists of two corrugated waveguide sections having a step of phase pi between the corrugations at the point of connection. The selective properties of a resonator of this type are significantly improved in comparison with a traditional two-mirror Bragg resonator. The output power was about 50 MW at a frequency of 30.7 GHz with the optimal parameters of the resonator, which corresponds to the efficiency of 35%, which is the highest for millimeter wavelength FEL. Radiation at the fundamental mode and the two side modes with the frequencies coincided to the 'cold' microwave testing was separately observed depending on the magnetic fields of the wiggler and solenoid.

  6. Longitudinal relaxation of mechanically free KH2PO4 type crystals. Piezoelectric resonance and sound attenuation

    Directory of Open Access Journals (Sweden)

    R.R.Levitskii

    2008-09-01

    Full Text Available Within the framework of proton model with taking into account the piezoelectric interaction with the shear strain ε6, a dynamic dielectric response of KD2PO4 type ferroelectrics is considered. Experimentally observed phenomena of crystal clamping by high frequency electric field, piezoelectric resonance and microwave dispersion are described. Ultrasound velocity and attenuation are calculated, peculiarities of their temperature dependence at the Curie points are described. Existence of a cut-off frequency in the frequency dependence of attenuation is predicted.

  7. Multicusp type machine for electron cyclotron resonance plasma with reduced dimensions

    Science.gov (United States)

    Amemiya, H.; Maeda, M.

    1996-03-01

    Plasmas are created in a cusp type magnetic trap using electron cyclotron resonance heating. The magnetic field is generated with permanent magnets forming a 12-pole, whereby the polarity at the ends of the rods has been reversed in order to obtain end plugs and to improve the plasma confinement. In this way, the plasma volume could be reduced such that the cross section was close to or smaller than the cutoff width of a circular waveguide. This increases the microwave power absorbed and gives a high plasma density even above the cutoff value.

  8. Multicusp type machine for electron cyclotron resonance plasma with reduced dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Amemiya, H.; Maeda, M. [The Institute of Physical and Chemical Research (RIKEN), Hirosawa 2-1, Wako-shi, Saitama-Pref., 351-01 (Japan)

    1996-03-01

    Plasmas are created in a cusp type magnetic trap using electron cyclotron resonance heating. The magnetic field is generated with permanent magnets forming a 12-pole, whereby the polarity at the ends of the rods has been reversed in order to obtain end plugs and to improve the plasma confinement. In this way, the plasma volume could be reduced such that the cross section was close to or smaller than the cutoff width of a circular waveguide. This increases the microwave power absorbed and gives a high plasma density even above the cutoff value. {copyright} {ital 1996 American Institute of Physics.}

  9. Cardiovascular magnetic resonance in rheumatology: Current status and recommendations for use

    NARCIS (Netherlands)

    Mavrogeni, S.I.; Kitas, G.D.; Dimitroulas, T.; Sfikakis, P.P.; Seo, P.; Gabriel, S.; Patel, A.R.; Gargani, L.; Bombardieri, S.; Matucci-Cerinic, M.; Lombardi, M.; Pepe, A.; Aletras, A.H.; Kolovou, G.; Miszalski, T.; Riel, P. van; Semb, A.; Gonzalez-Gay, M.A.; Dessein, P.; Karpouzas, G.; Puntmann, V.; Nagel, E.; Bratis, K.; Karabela, G.; Stavropoulos, E.; Katsifis, G.; Koutsogeorgopoulou, L.; Rossum, A. van; Rademakers, F.; Pohost, G.; Lima, J.A.

    2016-01-01

    Targeted therapies in connective tissue diseases (CTDs) have led to improvements of disease-associated outcomes, but life expectancy remains lower compared to general population due to emerging co-morbidities, particularly due to excess cardiovascular risk. Cardiovascular magnetic resonance (CMR) is

  10. Three-wave interaction during electron cyclotron resonance heating and current drive

    DEFF Research Database (Denmark)

    Nielsen, Stefan Kragh; Jacobsen, Asger Schou; Hansen, Søren Kjer

    2016-01-01

    Non-linear wave-wave interactions in fusion plasmas, such as the parametric decay instability (PDI) of gyrotron radiation, can potentially hamper the use of microwave diagnostics. Here we report on anomalous scattering in the ASDEX Upgrade tokamak during electron cyclotron resonance heating...

  11. 18-Electron Resonance Structures in the BCC Transition Metals and Their CsCl-type Derivatives.

    Science.gov (United States)

    Vinokur, Anastasiya I; Fredrickson, Daniel C

    2017-03-06

    Bonding in elemental metals and simple alloys has long been thought of as involving intense delocalization, with little connection to the localized bonds of covalent systems. In this Article, we show that the bonding in body-centered cubic (bcc) structures of the group 6 transition metals can in fact be represented, via the concepts of the 18-n rule and isolobal bonding, in terms of two balanced resonance structures. We begin with a reversed approximation Molecular Orbital (raMO) analysis of elemental Mo in its bcc structure. The raMO analysis indicates that, despite the low electron count (six valence electrons per Mo atom), nine electron pairs can be associated with any given Mo atom, corresponding to a filled 18-electron configuration. Six of these electron pairs take part in isolobal bonds along the second-nearest neighbor contacts, with the remaining three (based on the t2g d orbitals) interacting almost exclusively with first-nearest neighbors. In this way, each primitive cubic network defined by the second-nearest neighbor contacts comprises an 18-n electron system with n = 6, which essentially describes the full electronic structure of the phase. Of course, either of the two interpenetrating primitive cubic frameworks of the bcc structure can act as a basis for this discussion, leading us to write two resonance structures with equal weights for bcc-Mo. The electronic structures of CsCl-type variants with the same electron count can then be interpreted in terms of changing the relative weights of these two resonance structures, as is qualitatively confirmed with raMO analysis. This combination of raMO analysis with the resonance concept offers an avenue to extend the 18-n rule into other transition metal-rich structures.

  12. Seasonal affective disorder, winter type: current insights and treatment options

    Directory of Open Access Journals (Sweden)

    Meesters Y

    2016-11-01

    Full Text Available Ybe Meesters,1 Marijke CM Gordijn,2,3 1University Center for Psychiatry, University Medical Center Groningen, 2Department of Chronobiology, GeLifes, University of Groningen, Groningen, the Netherlands; 3Chrono@Work B.V., Groningen, the Netherlands Abstract: Seasonal affective disorder (SAD, winter type, is a seasonal pattern of recurrent major depressive episodes most commonly occurring in autumn or winter and remitting in spring/summer. The syndrome has been well-known for more than three decades, with light treatment being the treatment of first choice. In this paper, an overview is presented of the present insights in SAD. Description of the syndrome, etiology, and treatment options are mentioned. Apart from light treatment, medication and psychotherapy are other treatment options. The predictable, repetitive nature of the syndrome makes it possible to discuss preventive treatment options. Furthermore, critical views on the concept of SAD as a distinct diagnosis are discussed. Keywords: seasonal affective disorder, review, light treatment, medication, psychotherapy, prevention

  13. Molecular typing of Sarcocystis neurona: current status and future trends.

    Science.gov (United States)

    Elsheikha, Hany M; Mansfield, Linda S

    2007-10-21

    Sarcocystis neurona is an important protozoal pathogen because it causes the serious neurological disease equine protozoal myeloencephalitis (EPM). The capacity of this organism to cause a wide spectrum of neurological signs in horses and the broad geographic distribution of observed cases in the Americas drive the need for sensitive, reliable and rapid typing methods to characterize strains. Various molecular methods have been developed and used to diagnose EPM due to S. neurona, to identify S. neurona isolates and to determine the heterogeneity and evolutionary relatedness within this species and related Sarcocystis spp. These methods included sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), immuno-fluorescent assay (IFA), slide agglutination test (SAT), SnSAG-specific ELISA, random amplified polymorphic DNA (RAPD), PCR-based restriction fragment length polymorphism (RFLP), amplified fragment length polymorphism (AFLP) fingerprinting, and sequence analysis of surface protein genes, ribosomal genes, microsatellite alleles and other molecular markers. Here, the utility of these molecular methods is reviewed and evaluated with respect to the need for molecular approaches that utilize well-characterized polymorphic, simple, independent, and stable genetic markers. These tools have the potential to add to knowledge of the genetic population structure of S. neurona and to provide new insights into the pathogenesis of EPM and S. neurona epidemiology. In particular, these methods provide new tools to address the hypothesis that particular genetic variants are associated with adverse clinical outcomes (severe pathotypes). The ultimate goal is to utilize them in future studies to improve treatment and prevention strategies.

  14. Pheochromocytoma associated with neurofibromatosis type 1: concepts and current trends

    Directory of Open Access Journals (Sweden)

    Vogiaki Sophia

    2010-03-01

    Full Text Available Abstract Background Neurofibromatosis Type 1(NF-1 has autosomal dominant inheritance with complete penetrance, variable expression and a high rate of new mutation. Pheochromocytoma occurs in 0.1%-5.7% of patients with NF-1. Case presentation We present the case of a 37-year-old patient with laparoscopically resected pheochromocytoma. He was investigated for hypertension, flushing and ectopic heart beat. Abdominal CT and MRI revealed a mass measuring 8 × 4 cm in the right adrenal gland. The diagnosis of pheochromocytoma was confirmed by elevated 24-hour urine levels of VMA, metanephrines and catecholamines as well as positive MIBG scan. The patient presented with classic clinical features of NF-1, which was confirmed by pathologic evaluation of an excised skin nodule. The patient underwent laparoscopic right adrenalectomy through a transabdominal approach and was discharged on the second postoperative day, being normotensive. The patient is normotensive without antihypertensive therapy 11 years after the procedure. Conclusion Nowadays in the era of laparoscopy, patients with pheochromocytoma reach the operating theatre easier than in the past. Despite, the feasibility and oncological efficacy of the laparoscopic approach to the adrenals, continued long term follow-up is needed to establish the minimally invasive technique as the preferred approach. Furthermore, these patients should be further investigated for other neoplasias and stigmata of other neurocutaneous syndromes, taking into account the association of the familial pheochromo-cytoma with other familial basis inherited diseases.

  15. Development of dispersed-type sonophotocatalytic process using piezoelectric effect caused by ultrasonic resonance.

    Science.gov (United States)

    Hayashi, Naohito; Yasutomi, Ryosuke; Kasai, Eiki

    2010-06-01

    Recently, degradation of persistent organic pollutants (POPs) with low biodegradability in the environment and in industrial and municipal wastewaters has gained importance. In this study, a dispersed-type sonophotocatalysis (SP) process, which is a combination of sonolysis and photocatalysis with dispersed light sources, has been proposed for the effective and energy-efficient degradation of POPs. In this method, the piezoelectric effect caused by ultrasonic resonance in a piezoelectric element is used for producing luminescence in a LED. A luminescent device composed of eight UV-LEDs and a piezoelectric element was designed for dispersion of UV light in water; this device was confirmed to show luminescence under ultrasonic irradiation. Sonophotocatalytic degradation experiments were carried out using several such devices, and the results were compared with those obtained in sonolysis, photocatalysis, and fixed-type SP. The comparison showed that the degradation rate constants in fixed-type and dispersed-type SP were larger than the sum of the rate constants obtained for sonolysis and photocatalysis; further, the synergetic effect caused by the combination of sonolysis and photocatalysis was 7.5% and 18% in fixed-type and dispersed-type SP, respectively.

  16. 78 FR 44042 - Airworthiness Directives; Agusta S.p.A. Helicopters (Type Certificate Currently Held By...

    Science.gov (United States)

    2013-07-23

    ....A. Helicopters (Type Certificate Currently Held By AgustaWestland S.P.A) (AgustaWestland) AGENCY... Certificate Currently Held By Agustawestland S.p.A) (AgustaWestland): Docket No. FAA-2013-0643;...

  17. Current variables, definitions and endpoints of the European Cardiovascular Magnetic Resonance Registry

    Directory of Open Access Journals (Sweden)

    Schwitter Juerg

    2009-11-01

    Full Text Available Abstract Background Cardiovascular Magnetic Resonance (CMR is increasingly used in daily clinical practice. However, little is known about its clinical utility such as image quality, safety and impact on patient management. In addition, there is limited information about the potential of CMR to acquire prognostic information. Methods The European Cardiovascular Magnetic Resonance Registry (EuroCMR Registry will consist of two parts: 1 Multicenter registry with consecutive enrolment of patients scanned in all participating European CMR centres using web based online case record forms. 2 Prospective clinical follow up of patients with suspected coronary artery disease (CAD and hypertrophic cardiomyopathy (HCM every 12 months after enrolment to assess prognostic data. Conclusion The EuroCMR Registry offers an opportunity to provide information about the clinical utility of routine CMR in a large number of cases and a diverse population. Furthermore it has the potential to gather information about the prognostic value of CMR in specific patient populations.

  18. Cardiovascular magnetic resonance at 3.0T: Current state of the art

    Directory of Open Access Journals (Sweden)

    Gharib Ahmed M

    2010-10-01

    Full Text Available Abstract There are advantages to conducting cardiovascular magnetic resonance (CMR studies at a field strength of 3.0 Telsa, including the increase in bulk magnetization, the increase in frequency separation of off-resonance spins, and the increase in T1 of many tissues. However, there are significant challenges to routinely performing CMR at 3.0T, including the reduction in main magnetic field homogeneity, the increase in RF power deposition, and the increase in susceptibility-based artifacts. In this review, we outline the underlying physical effects that occur when imaging at higher fields, examine the practical results these effects have on the CMR applications, and examine methods used to compensate for these effects. Specifically, we will review cine imaging, MR coronary angiography, myocardial perfusion imaging, late gadolinium enhancement, and vascular wall imaging.

  19. Direct imaging of neural currents using ultra-low field magnetic resonance techniques

    Science.gov (United States)

    Volegov, Petr L.; Matlashov, Andrei N.; Mosher, John C.; Espy, Michelle A.; Kraus, Jr., Robert H.

    2009-08-11

    Using resonant interactions to directly and tomographically image neural activity in the human brain using magnetic resonance imaging (MRI) techniques at ultra-low field (ULF), the present inventors have established an approach that is sensitive to magnetic field distributions local to the spin population in cortex at the Larmor frequency of the measurement field. Because the Larmor frequency can be readily manipulated (through varying B.sub.m), one can also envision using ULF-DNI to image the frequency distribution of the local fields in cortex. Such information, taken together with simultaneous acquisition of MEG and ULF-NMR signals, enables non-invasive exploration of the correlation between local fields induced by neural activity in cortex and more `distant` measures of brain activity such as MEG and EEG.

  20. Spin-current resonances in a magnetically inhomogeneous 2D conducting system

    Science.gov (United States)

    Charkina, O. V.; Kalinenko, A. N.; Kopeliovich, A. I.; Pyshkin, P. V.; Yanovsky, A. V.

    2016-10-01

    The high-frequency transport in a two-dimensional conducting ring having an inhomogeneous collinear magnetic structure has been considered in the hydrodynamic approximation. It is shown that the frequency dependence on the radial electric conductivity of the ring exhibits resonances corresponding to new hybrid oscillations in such systems. The oscillation frequencies are essentially dependent on the applied electromagnetic field and the spin state of the system.

  1. Aluminum and boron nuclear quadrupole resonance with a direct current superconducting quantum interference device

    Science.gov (United States)

    Connor, C.; Chang, J.; Pines, A.

    1990-12-01

    We report the application of our dc SQUID (superconducting quantum interference device) spectrometer [C. Connor, J. Chang, and A. Pines, Rev. Sci. Instrum. 61, 1059(1990)] to nuclear quadrupole resonance (NQR) studies of aluminum-27, and boron-11 in crystalline and glassy solids. Our results give e2qQ/h=2.38 MHz and η=0.0 for α-Al2O3 at 4.2 K. For the natural mineral petalite (LiAlSi4O10), we obtain e2qQ/h=4.56 MHz and η=0.47. The quadrupole resonance frequency is 1467 kHz in boron nitride, and in the vicinity of 1300 kHz for various borates in the B2O3ṡxH2O system. The distribution of boron environments in a B2O3 glass gives rise to a linewidth of about 80 kHz in the SQUID detected resonance.

  2. Investigation of resonant Raman scattering in type II GaAs/AlAs superlattices

    CERN Document Server

    Choi, H

    2001-01-01

    GAMMA-related Type I outgoing RR spectra within several theoretical models. Thereby, the mechanisms of the Type II RR scattering, the origins of the RR lineshape and the polarisation dependence, are fully explained, clarifying the spectral features observed in the GaAs zone-centre optic phonon region. The Type II resonance also allows the observation of zone boundary (X-point) phonons from intervalley (IV) scattering. A model of the IV electron-phonon interaction involving X conduction band electrons and zone boundary phonons in Type II SLs is presented. With the predicted SL selection rules for IV scattering, the simultaneous observation of both the zone-boundary longitudinal acoustic and optic phonons can be understood and the spectral features quantitatively explained. As a consequence of the band alignment in GaAs/AIAs superlattices (SLs) and the indirect nature of bulk AIAs, quantum confinement can be used to engineer a Type II system. This produces an electron population in the AIAs longitudinal (X sub ...

  3. Energy transfer of surface wind-induced currents to the deep ocean via resonance with the Coriolis force

    Science.gov (United States)

    Ashkenazy, Yosef

    2017-03-01

    There are two main comparable sources of energy to the deep ocean-winds and tides. However, the identity of the most efficient mechanism that transfers wind energy to the deep ocean is still debated. Here we study, using oceanic general circulation model simulations and analytic derivations, the way that the wind directly supplies energy down to the bottom of the ocean when it is stochastic and temporally correlated or when it is periodic with a frequency that matches the Coriolis frequency. Basically, under these, commonly observed, conditions, one of the wind components resonates with the Coriolis frequency. Using reanalysis surface wind data and our simple model, we show that about one-third of the kinetic energy that is associated with wind-induced currents resides in the abyssal ocean, highlighting the importance of the resonance of the wind with the Coriolis force.

  4. Understanding and modeling Förster-type resonance energy transfer (FRET) introduction to FRET

    CERN Document Server

    Govorov, Alexander; Demir, Hilmi Volkan

    2016-01-01

    This Brief presents a historical overview of the Förster-type nonradiative energy transfer and a compilation of important progress in FRET research, starting from Förster until today, along with a summary of the current state-of-the-art. Here the objective is to provide the reader with a complete account of important milestones in FRET studies and FRET applications as well as a picture of the current status.

  5. Magnetic resonance imaging of athletic pubalgia and the sports hernia: current understanding and practice.

    Science.gov (United States)

    Khan, Waseem; Zoga, Adam C; Meyers, William C

    2013-02-01

    Magnetic resonance imaging (MRI) has become the standard imaging modality for activity-related groin pain. Lesions, including rectus abdominis/adductor aponeurosis injury and osteitis pubis, can be accurately identified and delineated in patients with clinical conditions termed athletic pubalgia, core injury, and sports hernia. A dedicated noncontrast athletic pubalgia MRI protocol is easy to implement and should be available at musculoskeletal MR imaging centers. This article will review pubic anatomy, imaging considerations, specific lesions, and common MRI findings encountered in the setting of musculoskeletal groin pain.

  6. Influence of Welding Current and Focal Position on the Resonant Absorption of Laser Radiation in a TIG Welding Arc

    Science.gov (United States)

    Emde, B.; Huse, M.; Hermsdorf, J.; Kaierle, S.; Wesling, V.; Overmeyer, L.

    The work presents the influence of welding current and focal position on the resonant absorption of diode laser radiation in a TIG welding arc. The laser beam is guided perpendicular to the electrical arc to avoid an interaction with the electrodes. Laser power measurements have shown a reduction of the measured laser power up to 18% after passing the electrical arc. This reduction results from the interaction of argon shielding gas atoms and laser radiation at 810.4 nm and 811.5 nm. The interaction is strongly affected by the adjusted welding current and the adjustment of the laser beam and the electrical arc. Lowering the welding current or shifting the laser beam out of the centerline of the electrical arc reduces the ionization probability. An increased ionization is necessary to decrease the resistance of the electrical arc.

  7. Current and future applications of magnetic resonance imaging and spectroscopy of the brain in hepatic encephalopathy

    Institute of Scientific and Technical Information of China (English)

    VP Bob Grover; M Alex Dresner; Daniel M Forton; Serena Counsell; David J Larkman; Nayna Patel; Howard C Thomas; Simon D Taylor-Robinson

    2006-01-01

    Hepatic encephalopathy (HE) is a common neuropsychiatric abnormality, which complicates the course of patients with liver disease and results from hepatocellular failure and/or portosystemic shunting.The manifestations of HE are widely variable and involve a spectrum from mild subclinical disturbance to deep coma. Research interest has focused on the role of circulating gut-derived toxins, particularly ammonia, the development of brain swelling and changes in cerebral neurotransmitter systems that lead to global CNS depression and disordered function. Until recently the direct investigation of cerebral function has been difficult in man. However, new magnetic resonance imaging (MRI) techniques provide a non-invasive means of assessment of changes in brain volume (coregistered MRI) and impaired brain function (fMRI), while proton magnetic resonance spectroscopy (1H MRS) detects changes in brain biochemistry, including direct measurement of cerebral osmolytes, such as myoinositol, glutamate and glutamine which govern processes intrinsic to cellular homeostasis, including the accumulation of intracellular water. The concentrations of these intracellular osmolytes alter with hyperammonaemia. MRS-detected metabolite abnormalities correlate with the severity of neuropsychiatric impairment and since MR spectra return towards normal after treatment, the technique may be of use in objective patient monitoring and in assessing the effectiveness of various treatment regimens.

  8. Fourier transform magnetic resonance current density imaging (FT-MRCDI) from one component of magnetic flux density.

    Science.gov (United States)

    Ider, Yusuf Ziya; Birgul, Ozlem; Oran, Omer Faruk; Arikan, Orhan; Hamamura, Mark J; Muftuler, L Tugan

    2010-06-01

    Fourier transform (FT)-based algorithms for magnetic resonance current density imaging (MRCDI) from one component of magnetic flux density have been developed for 2D and 3D problems. For 2D problems, where current is confined to the xy-plane and z-component of the magnetic flux density is measured also on the xy-plane inside the object, an iterative FT-MRCDI algorithm is developed by which both the current distribution inside the object and the z-component of the magnetic flux density on the xy-plane outside the object are reconstructed. The method is applied to simulated as well as actual data from phantoms. The effect of measurement error on the spatial resolution of the current density reconstruction is also investigated. For 3D objects an iterative FT-based algorithm is developed whereby the projected current is reconstructed on any slice using as data the Laplacian of the z-component of magnetic flux density measured for that slice. In an injected current MRCDI scenario, the current is not divergence free on the boundary of the object. The method developed in this study also handles this situation.

  9. Active Damping of LLCL-Filter Resonance Based on LC-Trap Voltage or Current Feedback

    DEFF Research Database (Denmark)

    Huang, Min; Wang, Xiongfei; Loh, Poh Chiang;

    2016-01-01

    . Active damping is presently more efficient, and can easily be realized by feeding back a state variable. For the LCL-filter, the variable is usually its middle capacitor current. However, with computational delays considered, a simple proportional damper cannot be used with the capacitor current. Instead...

  10. Grid-Current-Feedback Active Damping for LCL Resonance in Grid-Connected Voltage-Source Converters

    OpenAIRE

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2016-01-01

    This paper investigates active damping of LCL-filter resonance in a grid-connected voltage-source converter with only grid-current feedback control. Basic analysis in the s-domain shows that the proposed damping technique with a negative high-pass filter along its damping path is equivalent to adding a virtual impedance across the grid-side inductance. This added impedance is more precisely represented by a series RL branch in parallel with a negative inductance. The negative inductance helps...

  11. Nuclear magnetic resonance (NMR) imaging of Arnold-Chiari type I malformation with hydromyelia

    Energy Technology Data Exchange (ETDEWEB)

    DeLaPaz, R.L.; Brady, T.J.; Buonanno, F.S.; New, P.F.; Kistler, J.P.; McGinnis, B.D.; Pykett, I.L.; Taveras, J.M.

    1983-02-01

    Saturation recovery nuclear magnetic resonance (NMR) images and metrizamide computed tomography (CT) scans were obtained in an adult patient with a clinical history suggestive of syringomyelia. Both NMR and CT studies showed low lying cerebellar tonsils. The CT study demonstrated central cavitation of the spinal cord from the midthoracic to midcervical levels but could not exclude an intramedullary soft tissue mass at the cervico-medullary junction. The NMR images in transverse, coronal, and sagittal planes demonstrated extension of an enlarged central spinal cord cerebrospinal fluid space to the cervico-medullary junction. This was felt to be strong evidence for exclusion of an intramedullary soft tissue mass and in favor of a diagnosis of Arnold-Chiari Type I malformation with hydromyelia. The noninvasive nature of spinal cord and cervico-medullary junction evaluation with NMR is emphasized.

  12. Electron paramagnetic resonance spectroscopy in radiation research: Current status and perspectives

    Directory of Open Access Journals (Sweden)

    Sudha Rana

    2010-01-01

    Full Text Available Exposure to radiation leads to a number of health-related malfunctions. Ionizing radiation is more harmful than non-ionizing radiation, as it causes both direct and indirect effects. Irradiation with ionizing radiation results in free radical-induced oxidative stress. Free radical-mediated oxidative stress has been implicated in a plethora of diseased states, including cancer, arthritis, aging, Parkinson′s disease, and so on. Electron Paramagnetic Resonance (EPR spectroscopy has various applications to measure free radicals, in radiation research. Free radicals disintegrate immediately in aqueous environment. Free radicals can be detected indirectly by the EPR spin trapping technique in which these forms stabilize the radical adduct and produce characteristic EPR spectra for specific radicals. Ionizing radiation-induced free radicals in calcified tissues, for example, teeth, bone, and fingernail, can be detected directly by EPR spectroscopy, due to their extended stability. Various applications of EPR in radiation research studies are discussed in this review.

  13. Development of a resonant repeater tag for the enhancement of sensitivity and specificity in a wireless eddy current sensing scheme

    Science.gov (United States)

    Woo, Byungki; Andringa, Matthew; Wood, Sharon; Neikirk, Dean P.

    2006-03-01

    Eddy current sensing has been successfully used in various applications from testing heat exchange tubes for nuclear power plants to assessing dielectric thickness on printed circuit boards. However, in civil infrastructures cosmetic or cementitious surface material often keeps the probe or reader coil from accessing conductive medium inside the structure, resulting in reduced coupling as the distance increases between the DUT (device under test) and probe. Thus, the direct application of existing eddy current sensing technique is not very useful to detect flaws in civil infrastructures. To address this weak coupling problem, a simple scheme is proposed in which a resonant passive repeater tag is placed between the reader coil and the conducting test target. In this paper, the feasibility of detecting defects like cracks or fractures in conductive medium using a passive resonant tag and remote inductive pick-up as a method of interrogation is shown. Experimental data taken from simple setups to demonstrate the advantage of the proposed scheme are presented.

  14. Current tecniques and new perpectives research of magnetic resonance enterography in pediatric Crohn's disease.

    Science.gov (United States)

    Masselli, Gabriele; Mastroiacovo, Ilaria; De Marco, Emidio; Francione, Giulia; Casciani, Emanuele; Polettini, Elisabetta; Gualdi, Gianfranco

    2016-07-28

    Crohn's disease affects more than 500000 individuals in the United States, and about 25% of cases are diagnosed during the pediatric period. Imaging of the bowel has undergone dramatic changes in the past two decades. The endoscopy with biopsy is generally considered the diagnostic reference standard, this combination can evaluates only the mucosa, not inflammation or fibrosis in the mucosa. Actually, the only modalities that can visualize submucosal tissues throughout the small bowel are the computed tomography (CT) enterography (CTE) with the magnetic resonance enterography (MRE). CT generally is highly utilized, but there is growing concern over ionizing radiation and cancer risk; it is a very important aspect to keep in consideration in pediatric patients. In contrast to CTE, MRE does not subject patients to ionizing radiation and can be used to detect detailed morphologic information and functional data of bowel disease, to monitor the effects of medical therapy more accurately, to detect residual active disease even in patients showing apparent clinical resolution and to guide treatment more accurately.

  15. Current tecniques and new perpectives research of magnetic resonance enterography in pediatric Crohn’s disease

    Science.gov (United States)

    Masselli, Gabriele; Mastroiacovo, Ilaria; De Marco, Emidio; Francione, Giulia; Casciani, Emanuele; Polettini, Elisabetta; Gualdi, Gianfranco

    2016-01-01

    Crohn’s disease affects more than 500000 individuals in the United States, and about 25% of cases are diagnosed during the pediatric period. Imaging of the bowel has undergone dramatic changes in the past two decades. The endoscopy with biopsy is generally considered the diagnostic reference standard, this combination can evaluates only the mucosa, not inflammation or fibrosis in the mucosa. Actually, the only modalities that can visualize submucosal tissues throughout the small bowel are the computed tomography (CT) enterography (CTE) with the magnetic resonance enterography (MRE). CT generally is highly utilized, but there is growing concern over ionizing radiation and cancer risk; it is a very important aspect to keep in consideration in pediatric patients. In contrast to CTE, MRE does not subject patients to ionizing radiation and can be used to detect detailed morphologic information and functional data of bowel disease, to monitor the effects of medical therapy more accurately, to detect residual active disease even in patients showing apparent clinical resolution and to guide treatment more accurately. PMID:27551337

  16. Current tecniques and new perpectives research of magnetic resonance enterography in pediatric Crohn’s disease

    Institute of Scientific and Technical Information of China (English)

    Gabriele Masselli; Ilaria Mastroiacovo; Emidio De Marco; Giulia Francione; Emanuele Casciani; Elisabetta Polettini; Gianfranco Gualdi

    2016-01-01

    Crohn’s disease affects more than 500000 individuals in the United States, and about 25% of cases are diagnosed during the pediatric period. Imaging of the bowel has undergone dramatic changes in the past two decades. The endoscopy with biopsy is generally considered the diagnostic reference standard, this combination can evaluates only the mucosa, not inflammation or fibrosis in the mucosa. Actually, the only modalities that can visualize submucosal tissues throughout the small bowel are the computed tomography(CT) enterography(CTE) with the magnetic resonance enterography(MRE). CT generally is highly utilized, but there is growing concern over ionizing radiation and cancer risk; it is a very important aspect to keep in consideration in pediatric patients. In contrast to CTE, MRE does not subject patients to ionizing radiation and can be used to detect detailed morphologic information and functional data of bowel disease, to monitor the effects of medical therapy more accurately, to detect residual active disease even in patients showing apparent clinical resolution and to guide treatment more accurately.

  17. Implementation issues on the design of current loops based on resonant regulators for isolated microgrids

    DEFF Research Database (Denmark)

    Federico, de Bosio; Pastorelli, Michele; Antonio DeSouza Ribeiro, Luiz;

    2016-01-01

    This paper analyzes the influence of state feedback coupling between the capacitor voltage and inductor current in voltage source inverters (VSI) operating in stand-alone microgrids. A decoupling technique is proposed as an effective measure to enhance the dynamics. Further implementation issues ...

  18. Identify Structural Flaw Location and Type with an Inverse Algorithm of Resonance Inspection

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wei; Lai, Canhai; Sun, Xin

    2015-10-20

    To evaluate the fitness-for-service of a structural component and to quantify its remaining useful life, aging and service-induced structural flaws must be quantitatively determined in service or during scheduled maintenance shutdowns. Resonance inspection (RI), a non-destructive evaluation (NDE) technique, distinguishes the anomalous parts from the good parts based on changes in the natural frequency spectra. Known for its numerous advantages, i.e., low inspection cost, high testing speed, and broad applicability to complex structures, RI has been widely used in the automobile industry for quality inspection. However, compared to other contemporary direct visualization-based NDE methods, a more widespread application of RI faces a fundamental challenge because such technology is unable to quantify the flaw details, e.g. location, dimensions, and types. In this study, the applicability of a maximum correlation-based inverse RI algorithm developed by the authors is further studied for various flaw cases. It is demonstrated that a variety of common structural flaws, i.e. stiffness degradation, voids, and cracks, can be accurately retrieved by this algorithm even when multiple different types of flaws coexist. The quantitative relations between the damage identification results and the flaw characteristics are also developed to assist the evaluation of the actual state of health of the engineering structures.

  19. ABO Blood-Typing Using an Antibody Array Technique Based on Surface Plasmon Resonance Imaging

    Science.gov (United States)

    Houngkamhang, Nongluck; Vongsakulyanon, Apirom; Peungthum, Patjaree; Sudprasert, Krisda; Kitpoka, Pimpun; Kunakorn, Mongkol; Sutapun, Boonsong; Amarit, Ratthasart; Somboonkaew, Armote; Srikhirin, Toemsak

    2013-01-01

    In this study, readily available antibodies that are used in standard agglutination tests were evaluated for their use in ABO blood typing by a surface plasmon resonance imaging (SPR imaging) technique. Five groups of antibodies, including mixed clones of anti-A, anti-B, and anti-AB, and single clones of anti-A and anti-B, were used to construct the five-line detection arrays using a multichannel flow cell in the SPR imager. The red blood cell (RBC) samples were applied to a multichannel flow cell that was orthogonal to the detection line arrays for blood group typing. We found that the blood samples were correctly grouped in less than 12 min by the SPR imaging technique, and the results were consistent with those of the standard agglutination technique for all 60 samples. We found that mixed clones of antibodies provided 33%–68% greater change in the SPR signal than the single-clone antibodies. Applying the SPR imaging technique using readily available antibodies may reduce the costs of the antibodies, shorten the measurement time, and increase the throughput. PMID:24021965

  20. First results with the yin-yang type electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Suominen, P. [Department of Physics, University of Jyvaeskylae (JYFL), P.O. Box 35, FI-40014, Jyvaeskylae (Finland)]. E-mail: pekka.suominen@gmail.com; Ropponen, T.; Koivisto, H. [Department of Physics, University of Jyvaeskylae (JYFL), P.O. Box 35, FI-40014, Jyvaeskylae (Finland)

    2007-08-01

    Highly charged heavy-ion beams are often produced with Electron Cyclotron Resonance Ion Sources (ECRIS). The so-called conventional minimum-B ECRIS design includes two solenoid magnets and a multipole magnet (usually a hexapole). A minimum-B configuration can also be formed with 'yin-yang' ('baseball') type coils. Such a magnetic field configuration has been extensively tested in magnetic fusion experiments but not for the production of highly charged heavy ions. The application of the afore-mentioned coil structure to the production of multiply charged ion beams was studied. In this paper we present a design of a yin-yang type ion source known as the ARC-ECRIS and some preliminary experimental results. As a result of this work it was found that the ARC-ECRIS plasma is stable and capable of producing multiply charged ions. Many compromises were made in order to keep the costs of the prototype low. As a consequence, significant improvement can be expected in performance if the plasma size is increased and magnetic confinement is improved. At the end of this article an evolution model of the ARC-ECRIS and some future prospects are presented.

  1. Current technological advances in magnetic resonance with critical impact for clinical diagnosis and therapy.

    Science.gov (United States)

    Runge, Val M

    2013-12-01

    The last 5 years of technological advances with major impact on clinical magnetic resonance (MR) are discussed, with greater emphasis on those that are most recent. These developments have already had a critical positive effect on clinical diagnosis and therapy and presage continued rapid improvements for the next 5 years. This review begins with a discussion of 2 topics that encompass the breadth of MR, in terms of anatomic applications, contrast media, and MR angiography. Subsequently, innovations are discussed by anatomic category, picking the areas with the greatest development, starting with the brain, moving forward to the liver and kidney, and concluding with the musculoskeletal system, breast, and prostate. Two final topics are then considered, which will likely, with time, become independent major fields in their own right, interventional MR and MR positron emission tomography (PET).The next decade will bring a new generation of MR contrast media, with research focused on substantial improvements (>100-fold) in relaxivity (contrast effect), thus providing greater efficacy, safety, and tissue targeting. Magnetic resonance angiography will see major advances because of the use of compressed sensing, in terms of spatial and temporal resolution, with movement away from nondynamic imaging. The breadth of available techniques and tissue contrast has greatly expanded in brain imaging, benefiting both from the introduction of new basic categories of imaging techniques, such as readout-segmented echo planar imaging and 3D fast spin echo imaging with variable flip angles, and from new refinements specific to anatomic areas, such as double inversion recovery and MP2RAGE. Liver imaging has benefited from the development of techniques to easily and rapidly assess lipid, and will see, overall, a marked improvement in the next 5 years from new techniques on the verge of clinical introduction, such as controlled aliasing in parallel imaging results in higher acceleration

  2. Double injection, resonant-tunneling recombination, and current-voltage characteristics in double-graphene-layer structures

    Energy Technology Data Exchange (ETDEWEB)

    Ryzhii, M. [Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu 965-8580 (Japan); Ryzhii, V. [Research Institute for Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Institute of Ultra High Frequency Semiconductor Electronics, Russian Academy of Sciences, Moscow 111005 (Russian Federation); Otsuji, T. [Research Institute for Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Maltsev, P. P. [Institute of Ultra High Frequency Semiconductor Electronics, Russian Academy of Sciences, Moscow 111005 (Russian Federation); Leiman, V. G. [Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700 (Russian Federation); Ryabova, N. [Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu 965-8580 (Japan); Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University, Moscow 105005 (Russian Federation); Mitin, V. [Department of Electrical Engineering, University at Buffalo, Buffalo, New York 1460-1920 (United States)

    2014-01-14

    We evaluate the effect of the recombination associated with interlayer transitions in ungated and gated double-graphene-layer (GL) structures on the injection of electrons and holes. Using the proposed model, we derive analytical expressions for the spatial distributions of the electron and hole Fermi energies and the energy gap between the Dirac points in GLs as well as their dependences on the bias and gate voltages. The current-voltage characteristics are calculated as well. The model is based on hydrodynamic equations for the electron and hole transports in GLs under the self-consistent electric field. It is shown that in undoped double-GL structures with weak scattering of electrons and holes on disorder, the Fermi energies and the energy gap are virtually constant across the main portions of GLs, although their values strongly depend on the voltages and recombination parameters. In contrast, the electron and hole scattering on disorder lead to substantial nonuniformities. The resonant inter-GL tunneling enables N-shaped current-voltage characteristics provided that GLs are sufficiently short. The width of the current maxima is much larger than the broadening of the tunneling resonance. In the double-GL structures with relatively long GLs, the N-shaped characteristics transform into the Z-shaped characteristics. The obtained results are in line with the experimental observations [Britnell et al., Nat. Commun. 4, 1794–1799 (2013)] and might be useful for design and optimization of different devices based on double-GL structures, including field-effect transistors and terahertz lasers.

  3. Lipoprotein Particle Size and Concentration by Nuclear Magnetic Resonance and Incident Type 2 Diabetes in Women

    Science.gov (United States)

    Mora, Samia; Otvos, James D.; Rosenson, Robert S.; Pradhan, Aruna; Buring, Julie E.; Ridker, Paul M.

    2010-01-01

    OBJECTIVE Diabetic dyslipoproteinemia is characterized by low HDL cholesterol and high triglycerides. We examined the association of lipoprotein particle size and concentration measured by nuclear magnetic resonance (NMR) spectroscopy with clinical type 2 diabetes. RESEARCH DESIGN AND METHODS This was a prospective study of 26,836 initially healthy women followed for 13 years for incident type 2 diabetes (n = 1,687). Baseline lipids were measured directly and lipoprotein size and concentration by NMR. Cox regression models included nonlipid risk factors (age, race, smoking, exercise, education, menopause, blood pressure, BMI, family history, A1C, and C-reactive protein). NMR lipoproteins were also examined after further adjusting for standard lipids. RESULTS Incident diabetes was significantly associated with baseline HDL cholesterol, triglycerides, and NMR-measured size and concentration of LDL, IDL, HDL, and VLDL particles. The associations of these particles differed substantially by size. Small LDLNMR and small HDLNMR were positively associated with diabetes (quintile 5 vs. 1 [adjusted hazard ratios and 95% CIs], 4.04 [3.21–5.09] and 1.84 [1.54–2.19], respectively). By contrast, large LDLNMR and large HDLNMR were inversely associated (quintile 1 vs. 5, 2.50 [2.12–2.95] and 4.51 [3.68–5.52], respectively). For VLDLNMR, large particles imparted higher risk than small particles (quintile 5 vs. 1, 3.11 [2.35–4.11] and 1.31 [1.10–1.55], respectively). Lipoprotein particle size remained significant after adjusting for standard lipids and nonlipid factors. CONCLUSIONS In this prospective study of women, NMR lipoprotein size and concentrations were associated with incident type 2 diabetes and remained significant after adjustment for established risk factors, including HDL cholesterol and triglycerides. PMID:20185808

  4. Computed tomography and magnetic resonance imaging findings of nasal cavity hemangiomas according to histological type

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jun Ho; Park, Sun Won; Lim, Myung Kwan; Kim, Yeo Ju; Lee, Ha Young [Dept. of Radiology, Inha University School of Medicine, Incheon (Korea, Republic of); Kim, Soo Jin [Dept. of Radiology, Seoul National University College of Medicine, Seoul (Korea, Republic of); Jang, Tae Young [Dept. of Otolaryngology-Head and Neck Surgery, Inha University School of Medicine, Incheon (Korea, Republic of); Kang, Young Hye [Dept. of Radiology, nha University Hospital, Incheon (Korea, Republic of)

    2015-06-15

    To compare computed tomography (CT) and magnetic resonance imaging (MRI) findings between two histological types of nasal hemangiomas (cavernous hemangioma and capillary or lobular capillary hemangioma). CT (n = 20; six pre-contrast; 20 post-enhancement) and MRI (n = 7) images from 23 patients (16 men and seven women; mean age, 43 years; range, 13-73 years) with a pathologically diagnosed nasal cavity hemangioma (17 capillary and lobular capillary hemangiomas and six cavernous hemangiomas) were reviewed, focusing on lesion location, size, origin, contour, enhancement pattern, attenuation or signal intensity (SI), and bony changes. The 17 capillary and lobular hemangiomas averaged 13 mm (range, 4-37 mm) in size, and most (n = 13) were round. Fourteen capillary hemangiomas had marked or moderate early phase enhancement on CT, which dissipated during the delayed phase. Four capillary hemangiomas on MRI showed marked enhancement. Bony changes were usually not seen on CT or MRI (seen on five cases, 29.4%). Half of the lesions (2/4) had low SI on T1-weighted MRI images and heterogeneously high SI with signal voids on T2-weighted images. The six cavernous hemangiomas were larger than the capillary type (mean, 20.5 mm; range, 10-39 mm) and most had lobulating contours (n = 4), with characteristic enhancement patterns (three centripetal and three multifocal nodular), bony remodeling (n = 4, 66.7%), and mild to moderate heterogeneous enhancement during the early and delayed phases. CT and MRI findings are different between the two histological types of nasal hemangiomas, particularly in the enhancement pattern and size, which can assist in preoperative diagnosis and planning of surgical tumor excision.

  5. Civility and workplace bullying: resonance of Nightingale's persona and current best practices.

    Science.gov (United States)

    Lim, Fidelindo A; Bernstein, Ilya

    2014-01-01

    Conflict or aggression occurring between and among healthcare workers is undermining attempts to create a culture of safety in the workplace. Healthcare occupations have higher rates of workplace bullying (WPB), and intimidating behavior across healthcare settings has been shown to foster medical errors, increase the cost of care, and contribute to poor patient satisfaction and preventable adverse outcomes. WBP is also partially responsible for the high attrition among nurses, a particular concern in the current nursing shortage. Through a narrative that explores Florence Nightingale's professional persona and experience, this article outlines various factors that contribute to incivility and WPB, and provides suggestions for curriculum design that may help preempt incivility in tomorrow's nurses.

  6. ¹H magnetic resonance spectroscopy: a review of the current literature and its potential utility in veterinary oncology.

    Science.gov (United States)

    Lynch, Katherine; O'Brien, Robert

    2014-05-01

    Advanced imaging of veterinary cancer patients has evolved in recent years and modalities once limited to human medicine have now been described for diagnostic purposes in veterinary medicine (positron emission tomography/computed tomography, single-photon emission computed tomography, whole body magnetic resonance imaging). Magnetic resonance spectroscopy (MRS) is a non-invasive and non-ionizing technique that is well described in the human medical literature and is most frequently used to evaluate the metabolic activity of tissues with questionable malignant transformation. Differentiation of neoplastic tissue from surrounding normal tissue is dependent on variations in cellular metabolism. Positive identification of malignancy can be made when neoplastic alterations are occurring at the cellular level prior to gross anatomic changes. This improved, early detection of cancer occurrence (or recurrence) can improve patient survival and direct medical therapy. MRS techniques are largely underutilized in veterinary medicine, with current research predominantly limited to the brain (both evaluation of normal and diseased tissue). Given the clinical utility of MRS in humans, the technique may also be useful in the staging of cancer in veterinary medicine.

  7. Power requirements for electron cyclotron current drive and ion cyclotron resonance heating for sawtooth control in ITER

    CERN Document Server

    Chapman, I T; Sauter, O; Zucca, C; Asunta, O; Buttery, R J; Coda, S; Goodman, T; Igochine, V; Johnson, T; Jucker, M; La Haye, R J; Lennholm, M; Contributors, JET-EFDA

    2013-01-01

    13MW of electron cyclotron current drive (ECCD) power deposited inside the q = 1 surface is likely to reduce the sawtooth period in ITER baseline scenario below the level empirically predicted to trigger neo-classical tearing modes (NTMs). However, since the ECCD control scheme is solely predicated upon changing the local magnetic shear, it is prudent to plan to use a complementary scheme which directly decreases the potential energy of the kink mode in order to reduce the sawtooth period. In the event that the natural sawtooth period is longer than expected, due to enhanced alpha particle stabilisation for instance, this ancillary sawtooth control can be provided from > 10MW of ion cyclotron resonance heating (ICRH) power with a resonance just inside the q = 1 surface. Both ECCD and ICRH control schemes would benefit greatly from active feedback of the deposition with respect to the rational surface. If the q = 1 surface can be maintained closer to the magnetic axis, the efficacy of ECCD and ICRH schemes sig...

  8. A Quantitative Theoretical Framework For Protein-Induced Fluorescence Enhancement-Förster-Type Resonance Energy Transfer (PIFE-FRET)

    NARCIS (Netherlands)

    Lerner, Eitan; Ploetz, Evelyn; Hohlbein, Johannes; Cordes, Thorben; Weiss, Shimon

    2016-01-01

    Single-molecule, protein-induced fluorescence enhancement (PIFE) serves as a molecular ruler at molecular distances inaccessible to other spectroscopic rulers such as Förster-type resonance energy transfer (FRET) or photoinduced electron transfer. In order to provide two simultaneous measurements of

  9. A Quantitative Theoretical Framework for Protein-Induced Fluorescence Enhancement-Förster-Type Resonance Energy Transfer (PIFE-FRET)

    NARCIS (Netherlands)

    Lerner, Eitan; Ploetz, Evelyn; Hohlbein, Johannes; Cordes, Thorben; Weiss, Shimon

    2016-01-01

    Single-molecule, protein-induced fluorescence enhancement (PIFE) serves as a molecular ruler at molecular distances inaccessible to other spectroscopic rulers such as Förster-type resonance energy transfer (FRET) or photoinduced electron transfer. In order to provide two simultaneous measurements

  10. Myocardial Steatosis and Left Ventricular Function in Type 2 Diabetes Mellitus : Assessed with Magnetic Resonance Imaging and Spectroscopy

    NARCIS (Netherlands)

    Meer, Rutger Wouter van der

    2008-01-01

    The aim of the thesis was to provide more insight into the influence of myocardial steatosis on left ventricular function in healthy volunteers and in patients with type 2 diabetes mellitus. Therefore we developed a reproducible proton magnetic resonance (MR) spectroscopic technique with respiratory

  11. Coherent Zeeman resonance from electron spin coherence in a mixed-type GaAs/AlAs quantum well.

    Science.gov (United States)

    O'Leary, Shannon; Wang, Hailin; Prineas, John P

    2007-03-01

    Coherent Zeeman resonance from electron spin coherence is demonstrated in a Lambda-type three-level system, coupling electron spin states via trions. The optical control of electron density that is characteristic of a mixed-type quantum-well facilitates the study of trion formation as well as the effects of many-body interactions on the manifestation of electron spin coherence in the nonlinear optical response.

  12. Effects of relative phase on transient evolution in an open resonant ladder-type atomic system

    Institute of Scientific and Technical Information of China (English)

    Yang Yan-Ling; Liu Zhong-Bo; Wang Lei; Tong Dian-Min; Fan Xi-Jun

    2009-01-01

    In an open ladder-type resonant atomic system, variation in relative phase between probe and driving fields does not affect the transient evolution of populations, but it has remarkable effects on gain and dispersion of the probe field. No matter whether an incoherent pump is present or absent, transient and stationary gains without inversion (GWI) always can be obtained by choosing an appropriate value of the relative phase. When the incoherent pump is absent, the values of transient and stationary GWIs are much larger and the time interval required to reach the stationary value is longer than those when the incoherent pump is present. Varying the exit rate and the ratio between injection rates can obviously change the phase-dependent GWI. In addition, in the transient evolution process, the phenomenon of high dispersion (refractive index) without absorption occurs at some values of relative phase. In the corresponding closed system, the stationary GWI can be obtained by choosing an appropriate value of relative phase only when incoherent pump exists, moreover the gain is smaller than that in the open system.

  13. Muscle magnetic resonance imaging in spinal muscular atrophy type 3: Selective and progressive involvement.

    Science.gov (United States)

    Durmus, Hacer; Yilmaz, Ravza; Gulsen-Parman, Yesim; Oflazer-Serdaroglu, Piraye; Cuttini, Marina; Dursun, Memduh; Deymeer, Feza

    2017-05-01

    In this study we sought to identify magnetic resonance imaging (MRI) signs of selective muscle involvement and disease progression in patients with spinal muscular atrophy type 3b (SMA3b). Twenty-five patients with genetically confirmed SMA3b underwent MRI on a 1.5-Tesla MR scanner. MRI showed significantly more severe involvement of the iliopsoas than of the gluteus maximus muscles, and more severe involvement of the triceps brachii than of the biceps brachii muscles. The quadriceps femoris muscles were severely involved. The deltoid, adductor longus, portions of the hamstrings, gracilis, sartorius, and rectus abdominis muscles were well preserved. We found a significant positive correlation between MRI changes and disease duration for gluteus maximus and triceps brachii. Follow-up MRIs of 4 patients showed disease progression. This study confirms the pattern of selective muscle involvement suggested by previous studies and further refines muscle MRI changes in SMA3b. Progressive muscle involvement is implicated. Muscle Nerve 55: 651-656, 2017. © 2016 Wiley Periodicals, Inc.

  14. Structural and functional cardiac changes in myotonic dystrophy type 1: a cardiovascular magnetic resonance study

    Directory of Open Access Journals (Sweden)

    Hermans Mieke CE

    2012-07-01

    Full Text Available Abstract Background Myotonic dystrophy type 1 (MD1 is a neuromuscular disorder with potential involvement of the heart and increased risk of sudden death. Considering the importance of cardiomyopathy as a predictor of prognosis, we aimed to systematically evaluate and describe structural and functional cardiac alterations in patients with MD1. Methods Eighty MD1 patients underwent physical examination, electrocardiography (ECG, echocardiography and cardiovascular magnetic resonance (CMR. Blood samples were taken for determination of NT-proBNP plasma levels and CTG repeat length. Results Functional and structural abnormalities were detected in 35 patients (44%. Left ventricular systolic dysfunction was found in 20 cases, left ventricular dilatation in 7 patients, and left ventricular hypertrophy in 6 patients. Myocardial fibrosis was seen in 10 patients (12.5%. In general, patients had low left ventricular mass indexes. Right ventricular involvement was uncommon and only seen together with left ventricular abnormalities. Functional or structural cardiac involvement was associated with age (p = 0.04, male gender (p Conclusions CMR can be useful to detect early structural and functional myocardial abnormalities in patients with MD1. Myocardial involvement is strongly associated with conduction abnormalities, but a normal ECG does not exclude myocardial alterations. These findings lend support to the hypothesis that MD1 patients have a complex cardiac phenotype, including both myocardial and conduction system alteration.

  15. Electron paramagnetic resonance study on n-type electron-irradiated 3C-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, P; Rabia, K; Son, N T; Janzen, E [Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden); Ohshima, T; Morishita, N; Itoh, H [Japan Atomic Energy Research Institute, Takasaki 370-1292 (Japan); Isoya, J [University of Tsukuba, Tsukuba 305-8550 (Japan)], E-mail: paca@ifm.liu.se

    2008-03-15

    Electron Paramagnetic Resonance (EPR) was used to study defects in n-type 3C-SiC films irradiated by 3-MeV electrons at room temperature with a dose of 2x10{sup 18} cm{sup -2}. After electron irradiation, two new EPR spectra with an effective spin S = 1, labeled L5 and L6, were observed. The L5 center has C{sub 3v} symmetry with g = 2.004 and a fine-structure parameter D = 436.5x10{sup -4} cm{sup -1}. The L5 spectrum was only detected under light illumination and it could not be detected after annealing at {approx}550{sup 0}C. The principal z-axis of the D tensor is parallel to the <111>-directions, indicating the location of spins along the Si-C bonds. Judging from the symmetry and the fact that the signal was detected under illumination in n-type material, the L5 center may be related to the divacancy in the neutral charge state. The L6 center has a C{sub 2v}-symmetry with an isotropic g-value of g = 2.003 and the fine structure parameters D = 547.7x10{sup -4} cm{sup -1} and E = 56.2x10{sup -4} cm{sup -1}. The L6 center disappeared after annealing at a rather low temperature ({approx}200 deg. C), which is substantially lower than the known annealing temperatures for vacancy-related defects in 3C-SiC. This highly mobile defect may be related to carbon interstitials.

  16. Nonlinear Resonant Excitation of Fast Sausage Waves in Current-Carrying Coronal Loops

    Science.gov (United States)

    Mikhalyaev, B. B.; Bembitov, D. B.

    2014-11-01

    We consider a model of a coronal loop that is a cylindrical magnetic tube with two surface electric currents. Its principal sausage mode has no cut-off in the long-wavelength limit. For typical coronal conditions, the period of the mode is between one and a few minutes. The sausage mode of flaring loops could cause long-period pulsations observed in microwave and hard X-ray ranges. There are other examples of coronal oscillations: long-period pulsations of active-region quiet loops in the soft X-ray emission are observed. We assume that these can also be caused by sausage waves. The question arises of how the sausage waves are generated in quiet loops. We assume that they can be generated by torsional oscillations. This process can be described in the framework of the nonlinear three-wave interaction formalism. The periods of interacting torsional waves are similar to the periods of torsional oscillations observed in the solar atmosphere. The timescale of the sausage-wave excitation is not much longer than the periods of interacting waves, so that the sausage wave is excited before torsional waves are damped.

  17. Magnetic resonance visualization of conductive structures by sequence-triggered direct currents and spin-echo phase imaging

    Energy Technology Data Exchange (ETDEWEB)

    Eibofner, Frank; Wojtczyk, Hanne; Graf, Hansjörg, E-mail: hansjoerg.graf@med.uni-tuebingen.de, E-mail: drGraf@t-online.de [Section on Experimental Radiology, University Hospital Tübingen, Tübingen D-72076 (Germany); Clasen, Stephan [Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen D-72076 (Germany)

    2014-06-15

    Purpose: Instrument visualization in interventional magnetic resonance imaging (MRI) is commonly performed via susceptibility artifacts. Unfortunately, this approach suffers from limited conspicuity in inhomogeneous tissue and disturbed spatial encoding. Also, susceptibility artifacts are controllable only by sequence parameters. This work presents the basics of a new visualization method overcoming such problems by applying sequence-triggered direct current (DC) pulses in spin-echo (SE) imaging. SE phase images allow for background free current path localization. Methods: Application of a sequence-triggered DC pulse in SE imaging, e.g., during a time period between radiofrequency excitation and refocusing, results in transient field inhomogeneities. Dependent on the additional z-magnetic field from the DC, a phase offset results despite the refocusing pulse. False spatial encoding is avoided by DC application during periods when read-out or slice-encoding gradients are inactive. A water phantom containing a brass conductor (water equivalent susceptibility) and a titanium needle (serving as susceptibility source) was used to demonstrate the feasibility. Artifact dependence on current strength and orientation was examined. Results: Without DC, the brass conductor was only visible due to its water displacement. The titanium needle showed typical susceptibility artifacts. Applying triggered DC pulses, the phase offset of spins near the conductor appeared. Because SE phase images are homogenous also in regions of persistent field inhomogeneities, the position of the conductor could be determined with high reliability. Artifact characteristic could be easily controlled by amperage leaving sequence parameters unchanged. For an angle of 30° between current and static field visualization was still possible. Conclusions: SE phase images display the position of a conductor carrying pulsed DC free from artifacts caused by persistent field inhomogeneities. Magnitude and phase

  18. Structured exercise interventions for type 2 diabetes mellitus: Strength of current evidence

    Directory of Open Access Journals (Sweden)

    Mohammed Ejas Hussain

    2011-07-01

    Full Text Available Exercise, along with medical nutrition therapy and pharmacological interventions, is an important component in the clinical management of type 2 diabetes mellitus (T2D. Current clinical guidelines on type 2 diabetes provide no detailed information on the modalities of effective exercise intervention in the treatment of type 2 diabetes. Both endurance and resistance types of exercise seem to be equally effective in improving metabolic control in patients with type 2 diabetes. Determining the best method of providing exercise is clinically relevant to this population. This paper reviews the epidemiology of diabetes and problems of physical function associated with type 2 diabetes and discuss the benefits of exercise therapy on the parameters of glycemic control and function in type 2 diabetes patients, with special reference to Asian Indians. Based on the currently available literature, it is concluded that type 2 diabetes patients should be encouraged to participate in specifically designed exercise intervention programs. Attention should be paid to the avoidance of cardiovascular and musculoskeletal deconditioning. More clinical research is warranted to establish the efficacy of different dosages of exercise intervention in a holistic approach for type 2 diabetes subpopulations within different stages of the disease and various levels of co-morbidity.

  19. Boundary Conditions for 2D Boussinesq-type Wave-Current Interaction Equations

    Directory of Open Access Journals (Sweden)

    Mera M.

    2011-01-01

    Full Text Available This research focuses on the development of a set of two-dimensional boundary conditions for specific governing equations. The governing equations are existing Boussinesqtype equations which is capable of simulating wave-current interaction. The present boundary conditions consist of for waves only case and for currents only case. To simulate wave-current interaction, the two kinds of the present boundary conditions are then combined. A numerical model based on both the existing governing equations and the present boundary conditions is applied to simulation of currents only and of wave-current interaction propagating over a basin with a submerged shoal. The results of the numerical model show that the present boundary conditions go well with the existing Boussinesq-type wave-current interaction equations.

  20. Coherence-Resonance-Induced Neuronal Firing near a Saddle-Node and Homoclinic Bifurcation Corresponding to Type-I Excitability

    Institute of Scientific and Technical Information of China (English)

    JIA Bing; GU Hua-Guang; LI Yu-Ye

    2011-01-01

    @@ Excitability is an essential characteristic of excitable media such as nervous and cardiac systems.Different types of neuronal excitability are related to different bifurcation structures.We simulate the coherence resonance effect near a saddle-node and homoclinic bifurcation corresponding to type-I excitability in a theoretical neuron model,and recognize the obvious features of the corresponding firing pattern.Similar firing patterns are discovered in rat hippocampal CA1 pyramidal neurons.The results are not only helpful for understanding the dynamics of the saddle-node bifurcation and type-I excitability in a realistic nervous system,but also provide a practical indicator to identify types of excitability and bifurcation.%Excitability is an essential characteristic of excitable media such as nervous and cardiac systems. Different types of neuronal excitability are related to different bifurcation structures. We simulate the coherence resonance effect near a saddle-node and homoclinic bifurcation corresponding to type-I excitability in a theoretical neuron model, and recognize the obvious features of the corresponding firing pattern. Similar firing patterns are discovered in rat hippocampal CA1 pyramidal neurons. The results are not only helpful for understanding the dynamics of the saddle-node bifurcation and type-I excitability in a realistic nervous system, but also provide a practical indicator to identify types of excitability and bifurcation.

  1. Sandwich sign of Borrmann type 4 gastric cancer on diffusion-weighted magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiao-Peng, E-mail: zxp@bjcancer.org [Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiology, Peking University School of Oncology, Beijing Cancer Hospital and Institute, No. 52 Fu Cheng Road, Hai Dian District, Beijing 100142 (China); Tang, Lei; Sun, Ying-Shi [Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiology, Peking University School of Oncology, Beijing Cancer Hospital and Institute, No. 52 Fu Cheng Road, Hai Dian District, Beijing 100142 (China); Li, Zi-Yu; Ji, Jia-Fu [Department of Gastrointestinal Surgery, Peking University School of Oncology, Beijing Cancer Hospital and Institute, No. 52 Fu Cheng Road, Hai Dian District, Beijing 100142 (China); Li, Xiao-Ting [Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiology, Peking University School of Oncology, Beijing Cancer Hospital and Institute, No. 52 Fu Cheng Road, Hai Dian District, Beijing 100142 (China); Liu, Yi-Qiang [Department of Pathology, Peking University School of Oncology, Beijing Cancer Hospital and Institute, No. 52 Fu Cheng Road, Hai Dian District, Beijing 100142 (China); Wu, Qi [Department of Endoscopy, Peking University School of Oncology, Beijing Cancer Hospital and Institute, No. 52 Fu Cheng Road, Hai Dian District, Beijing 100142 (China)

    2012-10-15

    Objective: To assess the appearance of Borrmann type 4 (BT-4) gastric cancer on diffusion-weighted magnetic resonance imaging (DWI) and to investigate the potential of qualitative and quantitative DW images analysis to differentiate BT-4 gastric cancer from poorly distended normal stomach wall. Materials and methods: DWI was performed on 23 patients with BT-4 gastric cancer and 23 healthy volunteers. The signal characteristics and correlated histopathological basis of the cancers on DWI were investigated. The contrast-to-noise ratios (CNR) of cancer were compared between DWI and T1WI/T2WI{sub .} The thickness and apparent diffusion coefficient (ADC) of cancer and normal stomach wall were compared. Results: All of the gastric cancers displayed hyperintensity compared to the nearby normal gastric wall on DWI. A three-layer sandwich sign that demonstrated high signal intensity in the inner and outer layer, and low signal intensity in the intermediate layer was observed in 69.6% of cancers on DWI. The low signal intensity represents the muscularis propria through the comparison with pathology, and it is postulated that scattering distribution of the cancer cells in this layer causes less damage and subsequently less restriction of water movement, which causes the low signal intensity on DWI. The CNR obtained with DWI was higher than that with T1WI and T2WI (P < 0.001). The mean ADC value of BT-4 gastric cancer was significantly lower than the poorly distended normal stomach wall (1.12 ± 0.23 × 10{sup −3} mm{sup 2}/s vs. 1.93 ± 0.22 × 10{sup −3} mm{sup 2}/s, P < 0.01). Conclusion: DWI can highlight the signals of BT-4 gastric cancer which may present a characteristic three-layer sandwich sign, and ADC values are helpful in the discrimination of gastric cancer from poorly distended stomach wall.

  2. Coil-type Fano Resonances: a Plasmonic Approach to Magnetic Sub-diffraction Confinement

    KAUST Repository

    Panaro, Simone

    2015-05-10

    Matrices of nanodisk trimers are introduced as plasmonic platforms for the generation of localized magnetic hot-spots. In Fano resonance condition, the optical magnetic fields can be squeezed in sub-wavelength regions, opening promising scenarios for spintronics.

  3. Current limiting characteristics of transformer type SFCL with coupled secondary windings according to its winding direction

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sung Hun [Dept. of Electrical Engineering, Soongsil University, Seoul (Korea, Republic of); Han, Tae Hee [Dept. of Aero Materials Engineering, Jungwon University, Goesan (Korea, Republic of)

    2017-06-15

    In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding.

  4. Chemotransduction in the Carotid Body: K+ Current Modulated by Po2 in Type I Chemoreceptor Cells

    Science.gov (United States)

    Lopez-Barneo, Jose; Lopez-Lopez, Jose R.; Urena, Juan; Gonzalez, Constancio

    1988-07-01

    The ionic currents of carotid body type I cells and their possible involvement in the detection of oxygen tension (Po2) in arterial blood are unknown. The electrical properties of these cells were studied with the whole-cell patch clamp technique, and the hypothesis that ionic conductances can be altered by changes in Po2 was tested. The results show that type I cells have voltage-dependent sodium, calcium, and potassium channels. Sodium and calcium currents were unaffected by a decrease in Po2 from 150 to 10 millimeters of mercury, whereas, with the same experimental protocol, potassium currents were reversibly reduced by 25 to 50 percent. The effect of hypoxia was independent of internal adenosine triphosphate and calcium. Thus, ionic conductances, and particularly the O2-sensitive potassium current, play a key role in the transduction mechanism of arterial chemoreceptors.

  5. Monolithic MACS micro resonators

    Science.gov (United States)

    Lehmann-Horn, J. A.; Jacquinot, J.-F.; Ginefri, J. C.; Bonhomme, C.; Sakellariou, D.

    2016-10-01

    Magic Angle Coil Spinning (MACS) aids improving the intrinsically low NMR sensitivity of heterogeneous microscopic samples. We report on the design and testing of a new type of monolithic 2D MACS resonators to overcome known limitations of conventional micro coils. The resonators' conductors were printed on dielectric substrate and tuned without utilizing lumped element capacitors. Self-resonance conditions have been computed by a hybrid FEM-MoM technique. Preliminary results reported here indicate robust mechanical stability, reduced eddy currents heating and negligible susceptibility effects. The gain in B1 /√{ P } is in agreement with the NMR sensitivity enhancement according to the principle of reciprocity. A sensitivity enhancement larger than 3 has been achieved in a monolithic micro resonator inside a standard 4 mm rotor at 500 MHz. These 2D resonators could offer higher performance micro-detection and ease of use of heterogeneous microscopic substances such as biomedical samples, microscopic specimens and thin film materials.

  6. Differences in subthreshold resonance of hippocampal pyramidal cells and interneurons: the role of h-current and passive membrane characteristics

    OpenAIRE

    Zemankovics, Rita; Káli, Szabolcs; Paulsen, Ole; Freund, Tamás F.; Hájos, Norbert

    2010-01-01

    The intrinsic properties of distinct types of neuron play important roles in cortical network dynamics. One crucial determinant of neuronal behaviour is the cell's response to rhythmic subthreshold input, characterised by the input impedance, which can be determined by measuring the amplitude and phase of the membrane potential response to sinusoidal currents as a function of input frequency. In this study, we determined the impedance profiles of anatomically identified neurons in the CA1 reg...

  7. Current Limiting Performance of Three-Phase Concentric Transformer Type SFCL at Unbalanced Fault Conditions

    OpenAIRE

    Shirai, Yasuyuki; Noda, Syo; Yamabe, Kenta; Hattori, Keisuke; Baba, Jumpei; Nishihara, Taichi; Nitta, Tanzo; Kobayashi, Shinichi; Sato, Kenichi

    2013-01-01

    We have proposed a transformer type SFCL whose primary and secondary superconducting coils have rewound structure. The primary coil is connected to a power line. The secondary one is short-circuited and has fewer turns than the primary coil. For small fault current, only the secondary coil turns to normal state. Inductive component of impedance at the primary terminal mainly appears. For larger fault current, the primary coil also turns to normal state, resistive component additively appears....

  8. Observation of Current Structures at Type-III ELM Onset on EAST

    DEFF Research Database (Denmark)

    Yan, Ning; Naulin, Volker; Xu, G.

    In far scrape-o layer (SOL), alternating negative and positive burst structures in ion saturation current were detected at the onset of each type-III edge localized mode (ELM) on EAST. Different from the fast streaming phenomenon reported previously, one subsequent positive burst structure appears...... led generated by scrape-off layer current can ultimately trigger the ELM through the coupling with MHD modes inside the separatrix....

  9. Differences between spinocerebellar ataxias and multiple system atrophy-cerebellar type on proton magnetic resonance spectroscopy.

    Directory of Open Access Journals (Sweden)

    Jiing-Feng Lirng

    Full Text Available PURPOSE: A broad spectrum of diseases can manifest cerebellar ataxia. In this study, we investigated whether proton magnetic resonance spectroscopy (MRS may help differentiate spinocerebellar ataxias (SCA from multiple systemic atrophy- cerebellar type (MSA-C. MATERIAL AND METHODS: This prospective study recruited 156 patients with ataxia, including spinocerebellar ataxia (SCA types 1, 2, 3, 6 and 17 (N = 94 and MSA-C (N = 62, and 44 healthy controls. Single voxel proton MRS in the cerebellar hemispheres and vermis were measured. The differences were evaluated using nonparametric statistic tests. RESULTS: When compared with healthy controls, the cerebellar and vermis NAA/Cr and NAA/Cho were lower in all patients(p<0.002. The Cho/Cr was lower in SCA2 and MSA-C (p<0.0005. The NAA/Cr and Cho/Cr were lower in MSA-C or SCA2 comparing with SCA3 or SCA6. The MRS features of SCA1 were in between (p<0.018. The cerebellar NAA/Cho was lower in SCA2 than SCA1, SCA3 or SCA6 (p<0.04. The cerebellar NAA/Cho in MSA-C was lower than SCA3 (p<0.0005. In the early stages of diseases (SARA score<10, significant lower NAA/Cr and NAA/Cho in SCA2, SCA3, SCA6 or MSA-C were observed comparing with healthy controls (p<0.017. The Cho/Cr was lower in MSA-C or SCA2 (p<0.0005. Patients with MSA-C and SCA2 had lower NAA/Cr and Cho/Cr than SCA3 or SCA6 (p<0.016. CONCLUSION: By using MRS, significantly lower NAA/Cr, Cho/Cr and NAA/Cho in the cerebellar hemispheres and vermis were found in patients with ataxia (SCAs and MSA-C. Rapid neuronal degeneration and impairment of membrane activities were observed more often in patients with MSA-C than those with SCA, even in early stages. MRS could also help distinguish between SCA2 and other subtypes of SCAs. MRS ratios may be of use as biomarkers in early stages of disease and should be further assessed in a longitudinal study.

  10. Series transformer based diode-bridge-type solid state fault current limiter

    Institute of Scientific and Technical Information of China (English)

    Amir HEIDARY; Hamid RADMANESH; Seyed Hamid FATHI; G B GHAREHPETIAN

    2015-01-01

    We propose a novel series transformer based diode-bridge-type solid state fault current limiter (SSFCL). To control the fault current, a series RLC branch is connected to the secondary side of an isolation series transformer. Based on this RLC branch, two current limiting modes are created. In the first mode, R and C are bypassed via a paralleled power electronic switch (insulated-gate bipolar transistor, IGBT) and L remains connected to the secondary side of the transformer as a DC reactor. In the second mode, the series reactor impedance is not enough to limit the fault current. In this case, the fault current can be con-trolled by selecting a proper on-off duration of the parallel IGBT, across the series damping resistor (R) and capacitor, which inserts high impedance into the line to limit the fault current. Then, by controlling the magnitude of the DC reactor current, the fault current is reduced and the voltage of the point of common coupling (PCC) is kept at an acceptable level. In addition, in the new SSFCL, the series RC branch, connected in parallel with the IGBT, serves as a snubber circuit for decreasing the transient recovery voltage (TRV) of the IGBT during on-off states. Therefore, the power quality indices can be improved. The measure-ment results of a built prototype are presented to support the simulation and theoretical studies. The proposed SSFCL can limit the fault current without any delay and successfully smooth the fault current waveform.

  11. On the V-type asteroids outside the Vesta family. I. Interplay of nonlinear secular resonances and the Yarkovsky effect: the cases of 956 Elisa and 809 Lundia

    CERN Document Server

    Carruba, V; Roig, F; Ferraz-Mello, S; Nesvorny, D; Carruba, Valerio; Michtchenko, Tatiana; Roig, Fernando; Ferraz-Mello, Sylvio; Nesvorny', David

    2005-01-01

    Among the largest objects in the main belt, asteroid 4 Vesta is unique in showing a basaltic crust. It is also the biggest member of the Vesta family, which is supposed to originate from a large cratering event about 1 Gyr ago (Marzari et al. 1996). Most of the members of the Vesta family for which a spectral classification is available show a V-type spectra. Before the discovery of 1459 Magnya (Lazzaro et al. 2000) and of several V-type NEA (Xu 1995), all the known V-type asteroids were members of the Vesta family. Recently two V-type asteroids, 809 Lundia and 956 Elisa, (Florczak et al. 2002) have been discovered well outside the limits of the family, near the Flora family. We currently know 22 V-type asteroids outside the family, in the inner asteroid belt. In this work we investigate the possibility that these objects are former family members that migrated to their current positions via the interplay of Yarkovsky effect and nonlinear secular resonances. The main dynamical feature of 956 Elisa and 809 Lun...

  12. Co-current toroidal rotation-driven and turbulent stresses with resonant magnetic perturbations in the edge plasmas of the J-TEXT tokamak

    Science.gov (United States)

    Zhao, K. J.; Shi, Yuejiang; Liu, H.; Diamond, P. H.; Li, F. M.; Cheng, J.; Chen, Z. P.; Nie, L.; Ding, Y. H.; Wu, Y. F.; Chen, Z. Y.; Rao, B.; Cheng, Z. F.; Gao, L.; Zhang, X. Q.; Yang, Z. J.; Wang, N. C.; Wang, L.; Jin, W.; Xu, J. Q.; Yan, L. W.; Dong, J. Q.; Zhuang, G.; J-TEXT Team

    2016-07-01

    The acceleration of the co-current toroidal rotations around resonant surfaces by resonant magnetic perturbations (RMPs) through turbulence is presented. These experiments were performed using a Langmuir probe array in the edge plasmas of the J-TEXT tokamak. This study aims at understanding the RMP effects on edge toroidal rotations and exploring its control method. With RMPs, the flat electron temperature T e profile, due to magnetic islands, appears around resonant surfaces (Zhao et al 2015 Nucl. Fusion 55 073022). When the resonant surface is closer to the last closed flux surface, the flat T e profile vanishes with RMPs. In both cases, the toroidal rotations significantly increase in the direction of the plasma current around the resonant surfaces with RMPs. The characteristics of turbulence are significantly affected by RMPs around the resonant surfaces. The turbulence intensity profile changes and the poloidal wave vector k θ increases with RMPs. The power fraction of the turbulence components in the ion diamagnetic drift direction increases with RMPs. The measurements of turbulent Reynolds stresses are consistent with the toroidal flows that can be driven by turbulence. The estimations of the energy transfer between the turbulence and toroidal flows suggest that turbulence energy transfers into toroidal flows. The result has the implication of the intrinsic rotation being driven by RMPs via turbulence.

  13. Choice Of Input Data Type Of Artificial Neural Network To Detect Faults In Alternative Current Systems

    Directory of Open Access Journals (Sweden)

    T. Benslimane

    2006-01-01

    Full Text Available This paper present a study on different input data types of ANN used to detect faults such as over-voltage in AC systems (AC network , induction motor. The input data of ANN are AC voltage and current. In no fault condition, voltage and current are sinusoidal. The input data of the ANN may be the instantaneous values of voltage and current, their RMS values or their average values after been rectified. In this paper we presented different characteristics of each one of these data. A digital software C++ simulation program was developed and simulation results were presented.

  14. A design of novel type superconducting magnet for super-high field functional magnetic resonance imaging by using the harmonic analysis method of magnetic vector potentials

    Institute of Scientific and Technical Information of China (English)

    俎栋林; 郭华; 宋枭禹; 包尚联

    2002-01-01

    The approach of expanding the magnetic scalar potential in a series of Legendre polynomials is suitable for designing a conventional superconducting magnetic resonance imaging magnet of distributed solenoidal configuration. Whereas the approach of expanding the magnetic vector potential in associated Legendre harmonics is suitable for designing a single-solenoid magnet that has multiple tiers, in which each tier may have multiple layers with different winding lengths. A set of three equations to suppress some of the lowest higher-order harmonics is found. As an example, a 4T single-solenoid magnetic resonance imaging magnet with 4 × 6 layers of superconducting wires is de signed The degree of homogeneity in the 0.5m diameter sphere volume is better than 5.8 ppm. The same degree of homogeneity is retained after optimal integralization of turns in each correction layer. The ratio Bm/Bo in the single-solenoid magnet is 30%lower than that in the conventional six-solenoid magnet. This tolerates higher rated superconducting current in the coil. The Lorentz force of the coil in the single-solenoid system is also much lower than in the six-solenoid system. This novel type of magnet possesses significant advantage over conventional magnets, especially when used as a super-high field functional magnetic resonance imaging magnet.

  15. Development of a Direct Methanol Fuel Cell with Lightweight Disc Type Current Collectors

    Directory of Open Access Journals (Sweden)

    Yean-Der Kuan

    2014-05-01

    Full Text Available The direct methanol fuel cell (DMFC adopts methanol solution as a fuel suitable for low power portable applications. A miniature, lightweight, passive air-breathing design is therefore desired. This paper presents a novel planar disc-type DMFC with multiple cells containing a novel developed lightweight current collector at both the anode and cathode sides. The present lightweight current collector adopts FR4 Glass/Epoxy as the substrate with the current collecting areas located at the corresponding membrane electrolyte assembly (MEA areas. The current collecting areas are fabricated by sequentially coating a corrosion resistant layer and electrical conduction layer via the thermal evaporation technique. The anode current collector has carved flow channels for fuel transport and production. The cathode current collector has drilled holes for passive air breathing. In order to ensure feasibility in the present concept a 3-cell prototype DMFC module with lightweight disc type current collectors is designed and constructed. Experiments were conducted to measure the cell performance. The results show that the highest cell power output is 54.88 mW·cm−2 and successfully demonstrate the feasibility of this novel design.

  16. Spin and valley dependent line-type resonant peaks in electrically and magnetically modulated silicene quantum structures

    Science.gov (United States)

    Zhang, Yuanshan; Guo, Yong

    2017-02-01

    A barrier with a tunable spin-valley dependent energy gap in silicene could be used as a spin and valley filter. Meanwhile, special resonant modes in unique quantum structure can act as energy filters. Hence we investigate valley and spin transport properties in the potential silicene quantum structures, i.e., single ferromagnetic barrier, single electromagnetic barrier and double electric barriers. Our quantum transport calculation indicates that quantum devices of high accuracy and efficiency (100% polarization), based on modulated silicene quantum structures, can be designed for valley, spin and energy filtering. These intriguing features are revealed by the spin, valley dependent line-type resonant peaks. In addition, line-type peaks in different structure depend on spin and valley diversely. The filter we proposed is controllable by electric gating.

  17. Noether and Belinfante corrected types of currents for perturbations in the Einstein-Gauss-Bonnet gravity

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, A N, E-mail: anpetrov@rol.ru [Relativistic Astrophysics Group, Sternberg Astronomical Institute, Universitetskii Pr., 13, Moscow 119992 (Russian Federation)

    2011-11-07

    In the framework of an arbitrary D-dimensional metric theory, perturbations are considered on arbitrary backgrounds that are however solutions of the theory. Conserved currents for perturbations are presented following two known prescriptions: the canonical Noether theorem and the Belinfante symmetrization rule. Using generalized formulae, currents in the Einstein-Gauss-Bonnet (EGB) gravity for arbitrary types of perturbations on arbitrary curved backgrounds (not only vacuum) are constructed in an explicit covariant form. Special attention is paid to the energy-momentum tensors for perturbations which are an important part in the structure of the currents. We use the derived expressions for two applied calculations: (a) to present the energy density for weak flat gravitational waves in D-dimensional EGB gravity; (b) to construct the mass flux for the Maeda-Dadhich-Molina 3D radiating black holes of a Kaluza-Klein type in 6D EGB gravity. (paper)

  18. Noether and Belinfante corrected types of currents for perturbations in the Einstein-Gauss-Bonnet gravity

    CERN Document Server

    Petrov, A N

    2011-01-01

    In the framework of an arbitrary D-dimensional metric theory, perturbations are considered on arbitrary backgrounds, which, however, are solutions of the theory. Conserved currents for perturbations are presented following two known prescriptions: of the canonical Noether theorem and of the Belinfante symmetrization rule. On the basis of the generalized formulae, currents in the Einstein-Gauss-Bonnet (EGB) gravity for arbitrary types of perturbations on arbitrary curved backgrounds (not only vacuum) are constructed in the explicit covariant form. A more attention is paid to the energy-momentum tensors for perturbations as more important parts in the structure of the currents. To be tested the new expressions are used a) to present energy density for weak flat gravitational waves in D-dimensional EGB gravity; b) to present mass flux for the Maeda-Dadhich-Molina 3D radiating black holes of the Kaluza-Klein type in 6D EGB gravity.

  19. Pulsed Field Gradient Nuclear Magnetic Resonance and Applications in Yttrium Type Zeolites

    Science.gov (United States)

    Wu, Shaoxiong

    Molecular self-diffusion measurements by Pulsed Field Gradient Nuclear Magnetic Resonance (PFG NMR) spectroscopy can be applied to numerous fields. PFG NMR spectroscopy usually requires no special labeling for measuring hydrocarbon self-diffusion in a variety of samples. This is a significant advantage over using radioactive isotopes or photolabeled molecules since no special sample preparation or handling is required. A single set of experiments can yield diffusion coefficients and often can be performed in a few hours. The range of diffusion coefficients (10^{ -4} cm^2/s-10 ^{-10} cm^2/s) which can be determined by PFG NMR covers most ranges of molecular diffusion. This work describes the design of a PFG NMR spectrometer for measuring hydrocarbon self-diffusion in zeolites. The principles of PFG NMR spectroscopy are illustrated. A pulsed field gradient 60 MHz NMR spectrometer was constructed. Diffusion data were acquired by PFG NMR for standard samples of water, ammonia and glycerol and are in good agreement with those reported in the literature. Following verification of spectrometer performance, the self-diffusion coefficients of isobutane in cation exchanged Y type zeolites were determined. The results show that the mobility of molecules in zeolites depends on the nature of the cations. For small crystallite zeolites, intercrystalline and intracrystalline diffusion has been observed. The effective diffusion coefficients strongly depend on the concentration of adsorbate as well as the packing method. Large discrepancies between diffusion coefficients in zeolites measured by PFG NMR and by adsorption rate experiments have been reported. Surface area, crystallite size, percentage of water in the zeolite, percentage of cation exchanged into the zeolite and other physical chemical properties effect hydrocarbon diffusivity. Detailed methods for determining these properties are discussed. As an extended study of zeolite catalysts, the adsorption of ethylene on

  20. Are Participants Aware of the Type and Intensity of Transcranial Direct Current Stimulation?

    Directory of Open Access Journals (Sweden)

    Matthew F Tang

    Full Text Available Transcranial direct current stimulation (tDCS is commonly used to alter cortical excitability but no experimental study has yet determined whether human participants are able to distinguish between the different types (anodal, cathodal, and sham of stimulation. If they can then they are not blind to experimental conditions. We determined whether participants could identify different types of stimulation (anodal, cathodal, and sham and current strengths after experiencing the sensations of stimulation during current onset and offset (which are associated with the most intense sensations in Experiment 1 and also with a prolonged period of stimulation in Experiment 2. We first familiarized participants with anodal, cathodal, and sham stimulation at both 1 and 2 mA over either primary motor or visual cortex while their sensitivity to small changes in visual stimuli was assessed. The different stimulation types were then applied for a short (Experiment 1 or extended (Experiment 2 period with participants indicating the type and strength of the stimulation on the basis of the evoked sensations. Participants were able to identify the intensity of stimulation with shorter, but not longer periods, of stimulation at better than chance levels but identification of the different stimulation types was at chance levels. This result suggests that even after exposing participants to stimulation, and ensuring they are fully aware of the existence of a sham condition, they are unable to identify the type of stimulation from transient changes in stimulation intensity or from more prolonged stimulation. Thus participants are able to identify intensity of stimulation but not the type of stimulation.

  1. HLA typing in acute optic neuritis. Relation to multiple sclerosis and magnetic resonance imaging findings

    DEFF Research Database (Denmark)

    Frederiksen, J.L.; Madsen, H.O.; Ryder, L.P.

    1997-01-01

    OBJECTIVE: To study the association of brain magnetic resonance imaging (MRI) findings and HLA findings to clarify the relationship between monosymptomatic optic neuritis (ON) and ON as part of clinically definite multiple sclerosis (CDMS). DESIGN: Population-based cohort of patients with ON refe...

  2. Fano coil-type resonances: a plasmonic tool for magnetic field enhancement (Conference Presentation)

    Science.gov (United States)

    Panaro, Simone; Proietti Zaccaria, Remo; Toma, Andrea

    2016-09-01

    Spintronics and spin-based technology rely on the ultra-fast unbalance of the electronic spin population in quite localized spatial regions. However, as a matter of fact, the low susceptibility of conventional materials at high frequencies strongly limits these phenomena, rendering the efficiency of magnetically active devices insufficient for application purposes. Among the possible strategies which can be envisaged, plasmonics offers a direct approach to increase the effect of local electronic unbalancing processes. By confining and enhancing free radiation in nm-size spatial regions, plasmonic nano-assemblies have demonstrated to support very intense electric and magnetic hot-spots. In particular, very recent studies have proven the fine control of magnetic fields in Fano resonance condition. The near-field-induced out-of-phase oscillation of localized surface plasmons has manifested itself with the arising of magnetic sub-diffractive hot-spots. Here, we show how this effect can be further boosted in the mid-infrared regime via the introduction of higher order plasmonic modes. The investigated system, namely Moon Trimer Resonator, combines the high efficiency of a strongly coupled nano-assembly in Fano interferential condition with the elevated tunability of the quadrupolar resonance supported by a moon-like geometry. The fine control of the apical gap in this unique nanostructure, characterizes a plasmonic device able to tune its resonance without any consequence on the magnetic hot-spot size, thus enabling an efficient squeezing in the infrared.

  3. Fano coil-type resonances: a plasmonic tool for the magnetic field manipulation (Conference Presentation)

    Science.gov (United States)

    Panaro, Simone; Proietti Zaccaria, Remo; Toma, Andrea

    2017-02-01

    Spintronics and spin-based technology rely on the ultra-fast unbalance of the electronic spin population in quite localized spatial regions. However, as a matter of fact, the low susceptibility of conventional materials at high frequencies strongly limits these phenomena, rendering the efficiency of magnetically active devices insufficient for application purposes. Among the possible strategies which can be envisaged, plasmonics offers a direct approach to increase the effect of local electronic unbalancing processes. By confining and enhancing free radiation in nm-size spatial regions, plasmonic nano-assemblies have demonstrated to support very intense electric and magnetic hot-spots. In particular, very recent studies have proven the fine control of magnetic fields in Fano resonance condition. The near-field-induced out-of-phase oscillation of localized surface plasmons has manifested itself with the arising of magnetic sub-diffractive hot-spots. Here, we show how this effect can be further boosted in the mid-infrared regime via the introduction of higher order plasmonic modes. The investigated system, namely Moon Trimer Resonator (MTR), combines the high efficiency of a strongly coupled nano-assembly in Fano interferential condition with the elevated tunability of the quadrupolar resonance supported by a moon-like geometry. The fine control of the apical gap in this unique nanostructure, characterizes a plasmonic device able to tune its resonance without any consequence on the magnetic hot-spot size, thus enabling an efficient squeezing in the infrared.

  4. Proposal of rectifier type superconducting fault current limiter with non-inductive reactor (SFCL)

    Science.gov (United States)

    Mohammad Salim, Khosru; Muta, Itsuya; Hoshino, Tsutomu; Nakamura, Taketsune; Yamada, Masato

    2004-03-01

    A rectifier type superconducting fault current limiter (SFCL) with non-inductive reactor has been proposed. The concept behind this SFCL is the appearance of high impedance during non-superconducting state of the coil. In a hybrid bridge circuit, two superconducting coils connected in anti-parallel: a trigger coil and a limiting coil. Both the coils are magnetically coupled with each other and have same number of turns. There is almost zero flux inside the core and therefore the total inductance is small during normal operation. At fault time when the trigger coil current reaches to a certain level, the trigger coil changes from superconducting state to normal state. This super-to-normal transition of the trigger coil changes the current ratio of the coils and therefore the flux inside the reactor is no longer zero. So, the equivalent impedance of both the coils increased thus limits the fault current. We have carried out computer simulation using EMTDC and observed the results. A preliminary experiment has already been performed using copper wired reactor with simulated super-to-normal transition resistance and magnetic switches. Both the simulation and preliminary experiment shows good results. The advantage of using hybrid bridge circuit is that the SFCL can also be used as circuit breaker. Two separate bridge circuit can be used for both trigger coil and the limiter coil. In such a case, the trigger coil can be shutdown immediately after the fault to reduce heat and thus reduce the recovery time. Again, at the end of fault when the SFCL needs to re-enter to the grid, turning off the trigger circuit in the two-bridge configuration the inrush current can be reduced. This is because the current only flows through the limiting coil. Another advantage of this type of SFCL is that no voltage sag will appear during load increasing time as long as the load current stays below the trigger current level.

  5. Direct current superconducting quantum interference device spectrometer for pulsed nuclear magnetic resonance and nuclear quadrupole resonance at frequencies up to 5 MHz

    Science.gov (United States)

    TonThat, Dinh M.; Clarke, John

    1996-08-01

    A spectrometer based on a dc superconducting quantum interference device (SQUID) has been developed for the direct detection of nuclear magnetic resonance (NMR) or nuclear quadrupole resonance (NQR) at frequencies up to 5 MHz. The sample is coupled to the input coil of the niobium-based SQUID via a nonresonant superconducting circuit. The flux locked loop involves the direct offset integration technique with additional positive feedback in which the output of the SQUID is coupled directly to a low-noise preamplifier. Precession of the nuclear quadrupole spins is induced by a magnetic field pulse with the feedback circuit disabled; subsequently, flux locked operation is restored and the SQUID amplifies the signal produced by the nuclear free induction signal. The spectrometer has been used to detect 27Al NQR signals in ruby (Al2O3[Cr3+]) at 359 and 714 kHz.

  6. The dendritic location of the L-type current and its deactivation by the somatic AHP current both contribute to firing bistability in motoneurons.

    Science.gov (United States)

    Manuel, Marin; Zytnicki, Daniel; Meunier, Claude

    2014-01-01

    Spinal motoneurons may display a variety of firing patterns including bistability between repetitive firing and quiescence and, more rarely, bistability between two firing states of different frequencies. It was suggested in the past that firing bistability required that the persistent L-type calcium current be segregated in distal dendrites, far away from the spike generating currents. However, this is not supported by more recent data. Using a two compartment model of motoneuron, we show that the different firing patterns may also result from the competition between the more proximal dendritic component of the dendritic L-type conductance and the calcium sensitive potassium conductance responsible for afterhypolarization (AHP). Further emphasizing this point, firing bistability may be also achieved when the L-type current is put in the somatic compartment. However, this requires that the calcium-sensitive potassium conductance be triggered solely by the high threshold calcium currents activated during spikes and not by calcium influx through the L-type current. This prediction was validated by dynamic clamp experiments in vivo in lumbar motoneurons of deeply anesthetized cats in which an artificial L-type current was added at the soma. Altogether, our results suggest that the dynamical interaction between the L-type and afterhyperpolarization currents is as fundamental as the segregation of the calcium L-type current in dendrites for controlling the discharge of motoneurons.

  7. Some considerations on the current debate about typing resolution in solid organ transplantation

    OpenAIRE

    Vogiatzi, Paraskevi

    2016-01-01

    Background The shortage of suitable organs and achieved tolerance are uncontested main concerns in transplantation. Long waiting lists for deceased donors and limited numbers of living donors are the current scenarios. Kidney grafts from living donors have better overall survival compared to cadaveric and require less aggressive immunosuppressive regimens. The human leukocyte antigen (HLA) labs have the key role to test the recipient and donors compatibility based on typing and antibody profi...

  8. Optimization of a hot-cavity type resonant ionization laser ion source

    Energy Technology Data Exchange (ETDEWEB)

    Henares, J. L., E-mail: henares@ganil.fr; Lecesne, N.; Hijazi, L.; Bastin, B.; Leroy, R.; Osmond, B.; Vignet, J. L. [GANIL, BP 55027, 14076 Caen Cedex 5 (France); Kron, T.; Naubereit, P.; Wendt, K. [Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, 55099 Mainz (Germany); Lassen, J. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada); Le Blanc, F. [IPN Orsay, BP 1-91406 Orsay (France)

    2016-02-15

    Resonant Ionization Laser Ion Source (RILIS) is nowadays an important technique in many Radioactive Ion Beam (RIB) facilities for its reliability and ability to ionize efficiently and element selectively. Grand Accélérateur National d’Ions Lourds (GANIL) Ion Source using Electron Laser Excitation (GISELE) is an off-line test bench for RILIS developed to study a fully operational resonant laser ion source at GANIL facility. The ion source body has been designed as a modular system to investigate different experimental approaches by varying the design parameters, to develop the future on-line laser ion source. The aim of this project is to determine the best technical solution which combines high selectivity and ionization efficiency with small ion beam emittance and stable long term operation. Latest results concerning emittance and time profile development as a function of the temperature for different ion source versions will be presented.

  9. Multicusp type electron cyclotron resonance plasma with arrangement of permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Amemiya, H.; Maeda, M. [Institute of Physical and Chemical Research, Wako, Saitama (Japan)

    1995-09-01

    ECR (electron cyclotron resonance) plasmas are generated in a multicusp field of 12-pole formed by permanent magnets, where the polarity of the magnetic field at the end sections is reversed to reflect axially drifting electrons as in the mirror field. Furthermore, the radius of multicusp is contracted below the cut-off radius of the waveguide in vacuum. This is effective in increasing the microwave power absorbed in the plasma and the ion density. (author).

  10. Effect of Shenmai Injection on L-type Calcium Current of Diaphragmatic Muscle in Rats

    Institute of Scientific and Technical Information of China (English)

    赵丽敏; 熊盛道; 牛汝楫; 徐永健; 张珍祥

    2004-01-01

    In this study, whole cell patch clamp recording technique was employed to investigate the effect of Shenmai Injection (SMI) on L-type calcium current of diaphragmatic muscle in rats. The result showed that when the diaphragmatic muscle cell was held at -80 mV and depolarized to +60 mV, 10 μl/ml, 50 μl/ml and 100μl/ml SMI enhanced the inner peak L-type calcium current from -(6.8±0.7) pA/pF (n=7) to -(7.3±0.8) pA/pF (P>0.05, n=7), -(8.6±1.0) pA/pF (P<0.05, n=7) and -(9.4±1.2) pA/pF (P<0.05, n=7), respectively. The rates of L-type calcium current were increased by (7. 34±2.37) %, (25. 72±5.94)% , and (38. 16±7.33)% ,respectively. However, it had no significant effect on maximal activation potential and reversal potential. Our results suggested that SMI could activate the calcium channel of the diaphragmatic fibers of the rats, increase the influx of Ca2+ , and enhance the contractility of diaphragmatic muscles.

  11. Accessory subunit KChIP2 modulates the cardiac L-type calcium current

    DEFF Research Database (Denmark)

    Thomsen, Morten B; Wang, Chaojian; Ozgen, Nazira

    2009-01-01

    Complex modulation of voltage-gated Ca2+ currents through the interplay among Ca2+ channels and various Ca(2+)-binding proteins is increasingly being recognized. The K+ channel interacting protein 2 (KChIP2), originally identified as an auxiliary subunit for K(V)4.2 and a component of the transient...... outward K+ channel (I(to)), is a Ca(2+)-binding protein whose regulatory functions do not appear restricted to K(V)4.2. Consequently, we hypothesized that KChIP2 is a direct regulator of the cardiac L-type Ca2+ current (I(Ca,L)). We found that I(Ca,L) density from KChIP2(-/-) myocytes is reduced by 28......% compared to I(Ca,L) recorded from wild-type myocytes (Pchannel current, as shown in a transfected cell line devoid of confounding cardiac ion currents. I(Ca,L) regulation by KChIP2 was independent of Ca2+ binding...

  12. Some considerations on the current debate about typing resolution in solid organ transplantation.

    Science.gov (United States)

    Vogiatzi, Paraskevi

    2016-01-01

    The shortage of suitable organs and achieved tolerance are uncontested main concerns in transplantation. Long waiting lists for deceased donors and limited numbers of living donors are the current scenarios. Kidney grafts from living donors have better overall survival compared to cadaveric and require less aggressive immunosuppressive regimens. The human leukocyte antigen (HLA) labs have the key role to test the recipient and donors compatibility based on typing and antibody profile. The current standard molecular procedure in solid organ transplantation is low-resolution typing, at the antigen level. In this commentary, the merits of high versus low degree of typing resolution in solid organ transplantation are discussed. Critical questions and reasons to bring high-resolution typing as a routine test in health system are considered. Specifically, with the introduction of the next-generation sequencing (NGS) in HLA, the pros and cons in living donation and benefits after deceased donation are critically evaluated. NGS has the potential to improve the transplant rates and the overall graft survival. Alternative strategies to increase in demanding the number of transplants are briefly highlighted.

  13. A-current modifies the spike of C-type neurones in the rabbit nodose ganglion.

    Science.gov (United States)

    Ducreux, C; Puizillout, J J

    1995-07-15

    1. In the rabbit nodose ganglion, C-type fibre neurones (C neurones) can be divided into two subtypes according to their after-hyperpolarizing potential (AHP) i.e. those with a fast AHP only and those with a fast AHP and a subsequent slow AHP produced by a slow calcium-dependent potassium current. In addition we have shown that some C neurones can be divided into two groups according to the effect of membrane hyperpolarization on their spikes i.e. type 1 in which duration and amplitude do not change and type 2 in which duration and amplitude decrease significantly. 2. In the present report we studied the effect of A-current (IA) on spike duration, amplitude and slow AHP using intracellular recording techniques. 3. To detect the presence of IA, we first applied a series of increasing rectangular hyperpolarizing pulses to remove IA inactivation and then a short depolarizing pulse to trigger a spike. In type 1 C neurones the lag time of the spike in relation to hyperpolarization remains constant whereas in type 2 C neurones the spike only appears after IA inactivation and lag time in relation to hyperpolarization is lengthened. Thus, type 2 C neurones have an IA while type 1 C neurones do not. The fact that addition of cadmium did not change the lag time in type 2 C neurones shows that the IA is not calcium dependent. 4. Nodose neurones can be orthodromically activated by stimulation of the vagal peripheral process. In this way, after a hyperpolarizing pulse, IA can be fully activated by the orthodromic spike itself. Under these conditions it is possible to analyse the effects of IA on the spike. This was done by increasing either the hyperpolarizing potential, pulse duration, or the delay of the spike after the end of the pulse. We observed that maximum IA inactivation removal was always associated with the lowest duration and amplitude of the spike. 5. When IA inhibitors, 4-aminopyridine (4-AP) or catechol, were applied to type 2 C neurones, the delay of the spike

  14. Assessment of magnetic resonance images of displacement of the disc of the temporomandibular joint in different types of condylar fracture.

    Science.gov (United States)

    Zheng, JiSi; Zhang, ShanYong; Yang, Chi; Abdelrehem, Ahmed; He, DongMei; Chiu, HanHsuan

    2016-01-01

    To evaluate the displacement of the disc of the temporomandibular joint (TMJ) in different types of condylar fracture we studied 160 patients (222 joints) from May 2009-June 2014. All patients had computed tomographic scans (CT) and magnetic resonance images (MRI) taken preoperatively, and 24 patients (32 joints) had MRI postoperatively. CT scans were reviewed to categorise the types of condylar fracture (intracapsular, condylar neck, and subcondylar), and intracapsular condylar fractures were further classified into subtypes A, B, C, and M. MRI were then reviewed to record the position of the disc in each type of condylar fracture. The results were compared using the chi square test. There were 160 intracapsular condylar fractures, 40 fractures of the condylar neck, and 22 subcondylar fractures. Of the intracapsular condylar fractures, 75 were type A, 49 type B, 11 type C, and 25 type M. Discs were displaced in 153 intracapsular condylar fractures, 17 fractures of the condylar neck, and eight subcondylar fractures. Among the type A intracapsular condylar fractures, discs were displaced in 71/75, type B in 47/49, type C in 10/11, and in all 25 type M. The incidence of displaced discs between intracapsular condylar fractures on the one hand, and those of the condylar neck or subcondylar region on the other, was significant (pcondylar fractures. Postoperative MRI showed successful results in 28/32 joints. Intracapsular condylar fractures were more likely to have displaced discs than the other types. But there were no differences among different subtypes of intracapsular condylar fractures.

  15. Proportional integral plus multi-frequency resonant current controller for grid-connected voltage source converter under imbalanced and distorted supply voltage conditions

    Institute of Scientific and Technical Information of China (English)

    Jia-bing HU; Wei ZHANG; Hong-sheng WANG; Yi-kang HE; Lie XU

    2009-01-01

    This paper proposes a current control scheme for a grid-connected pulse width modulator (PWM) voltage source converter (GC-VSC) under imbalanced and distorted supply voltage conditions. The control scheme is implemented in the positive synchronously rotating reference frame and composed of a single proportional integral (PI) regulator and multi-frequency resonant controllers tuned at the frequencies of 2ω and 6ω, respectively. The experimental results, with the target of eliminating the active power oscillations and current harmonics on a prototype GC-VSC system, validate the feasibility of the proposed current control scheme during supply voltage imbalance and distortion.

  16. First operation and effect of a new tandem-type ion source based on electron cyclotron resonance

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Yushi, E-mail: kato@eei.eng.osaka-u.ac.jp; Kimura, Daiju; Yano, Keisuke; Kumakura, Sho; Imai, Youta; Nishiokada, Takuya; Nagaya, Tomoki; Hagino, Shogo; Otsuka, Takuro; Sato, Fuminobu [Division of Electrical, Electronic and Information Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka 565-0871 (Japan)

    2016-02-15

    A new tandem type source has been constructed on the basis of electron cyclotron resonance plasma for producing synthesized ion beams in Osaka University. Magnetic field in the first stage consists of all permanent magnets, i.e., cylindrically comb shaped one, and that of the second stage consists of a pair of mirror coil, a supplemental coil and the octupole magnets. Both stage plasmas can be individually operated, and produced ions in which is energy controlled by large bore extractor also can be transported from the first to the second stage. We investigate the basic operation and effects of the tandem type electron cyclotron resonance ion source (ECRIS). Analysis of ion beams and investigation of plasma parameters are conducted on produced plasmas in dual plasmas operation as well as each single operation. We describe construction and initial experimental results of the new tandem type ion source based on ECRIS with wide operation window for aiming at producing synthesized ion beams as this new source can be a universal source in future.

  17. An Evaluation of the Permittivity of Two Different Rock Types Using Microwave Resonator and Waveguide Cutoff Principles

    Science.gov (United States)

    Olkkonen, Martta-Kaisa; Eskelinen, Pekka; Huuskonen-Snicker, Eeva; Pellinen, Terhi; Olmos Martinez, Pablo

    2015-01-01

    Methods of measuring the complex permittivity of different rock types are demonstrated in the frequency range from 6 GHz to 17 GHz. The used methods are based on the cylindrical resonator and waveguide cutoff frequency principles. This study is part of a larger research project that aims to characterize the electrical properties of asphalt for road surveying purposes. The studied rock types are metavolcanic rock with intermediate composition and pegmatite. The permittivity values gained with the resonator method are 6.2 for the metavolcanic rock and 4.5 for the pegmatite rock type, whereas the imaginary parts are 0.04 and 0.02. The permittivity values gained with the cutoff frequency method are 6.17 and 4.76 respectively. A reference measurement was made only for the metavolcanic rock in a transmission configuration with two antennas and the permittivity result was 6.21. The three different methods provide consistent permittivity values and are suitable for reliable permittivity evaluation.

  18. Two outward potassium current types are expressed during the neural differentiation of neural stem cells**

    Institute of Scientific and Technical Information of China (English)

    Ruiying Bai; Guowei Gao; Ying Xing; Hong Xue

    2013-01-01

    The electrophysiological properties of potassium ion channels are regarded as a basic index for determining the functional differentiation of neural stem cells. In this study, neural stem cells from the hippocampus of newborn rats were induced to differentiate with neurotrophic growth factor, and the electrophysiological properties of the voltage-gated potassium ion channels were observed. Immunofluorescence staining showed that the rapidly proliferating neural stem cells formed spheres in vitro that expressed high levels of nestin. The differentiated neurons were shown to express neuron-specific enolase. Flow cytometric analysis revealed that the neural stem cells were actively dividing and the percentage of cells in the S + G2/M phase was high. However, the ratio of cells in the S + G2/M phase decreased obviously as differentiation proceeded. Whole-cellpatch-clamp re-cordings revealed apparent changes in potassium ion currents as the neurons differentiated. The potassium ion currents consisted of one transient outward potassium ion current and one delayed rectifier potassium ion current, which were blocked by 4-aminopyridine and tetraethylammonium, respectively. The experimental findings indicate that neural stem cells from newborn rat hippo-campus could be cultured and induced to differentiate into functional neurons under defined condi-tions in vitro. The differentiated neurons expressed two types of outward potassium ion currents similar to those of mature neurons in vivo.

  19. Adult onset glycogen storage disease type II (adult onset Pompe disease): report and magnetic resonance images of two cases

    Energy Technology Data Exchange (ETDEWEB)

    Del Gaizo, Andrew [Emory University School of Medicine, Radiology Resident, Atlanta, GA (United States); Banerjee, Sima [Emory University School of Medicine, Musculoskeletal Radiology Department, Atlanta, GA (United States); Terk, Michael [Emory University School of Medicine, Radiology, Division of Musculoskeletal Imaging, Atlanta, GA (United States)

    2009-12-15

    Glycogen storage disease type II (GSDII), also referred to as Pompe disease or acid maltase deficiency, is a rare inherited condition caused by a deficiency in acid alpha-glucosidase (GAA) enzyme activity. The condition is often classified by age of presentation, with infantile and late onset variants (Laforet et al. J Neurology 55:1122-8, 2000). Late onset tends to present with progressive proximal muscle weakness and respiratory insufficiency (Winkel et al. J Neurology 252:875-84, 2005). We report two cases of biopsy confirmed adult onset GSDII, along with key Magnetic Resonance (MR) images. (orig.)

  20. Electric and magnetic properties computed for valence bond structures: is there a link between pauling resonance energy and ring current?

    Science.gov (United States)

    Havenith, Remco W A

    2006-04-28

    To establish the link between the aromaticity descriptors based on the Pauling resonance energy and the molecular properties, the electric (polarizability) and magnetic (magnetizability) field response properties have been calculated using the valence bond approach for various molecules and their individual Kekulé resonance structures. The results show that there is no direct relationship between the Pauling resonance energy and the properties; the response properties are weighted averages of the properties of the individual structures. According to the aromaticity criteria based on molecular properties, one-structure benzene would be aromatic; thus, concerning molecular properties, spin-coupled bonds do not behave like localized bonds in Lewis structures, with which they are usually associated.

  1. A PAC Based Current Feedforward Control for Three-Phase PWM Voltage-Type Converter

    Institute of Scientific and Technical Information of China (English)

    屈克庆; 陈国呈; 孙承波

    2004-01-01

    This paper presents a novel current feedforward control strategy for a three-phase pulse-width modulation (PWM) DC voltage-type converter based on phase and amplitude control (PAC). With right-angle triangle relation of phasors and principle of conservation of energy, a phasor adjustment method and the relevant low-frequency mathematical model of the system are analyzed in detail, both in rectification and regeneration modes for the converter, are discussed. For improving the traditional PAC dynamic performance, variable load current is detected indirectly by the change of the DC voltage, which is fed to the control system as an additional control variable to generate modulation index and phase angle. Also, the algorithm is derived and the system principle is introduced. Experimental results from a 3 kw laboratory device are included to demonstrate the effectiveness of the proposed control strategy.

  2. Design of Diaphragm and Coil for Stable Performance of an Eddy Current Type Pressure Sensor.

    Science.gov (United States)

    Lee, Hyo Ryeol; Lee, Gil Seung; Kim, Hwa Young; Ahn, Jung Hwan

    2016-07-01

    The aim of this work was to develop an eddy current type pressure sensor and investigate its fundamental characteristics affected by the mechanical and electrical design parameters of sensor. The sensor has two key components, i.e., diaphragm and coil. On the condition that the outer diameter of sensor is 10 mm, two key parts should be designed so as to keep a good linearity and sensitivity. Experiments showed that aluminum is the best target material for eddy current detection. A round-grooved diaphragm is suggested in order to measure more precisely its deflection caused by applied pressures. The design parameters of a round-grooved diaphragm can be selected depending on the measuring requirements. A developed pressure sensor with diaphragm of t = 0.2 mm and w = 1.05 mm was verified to measure pressure up to 10 MPa with very good linearity and errors of less than 0.16%.

  3. Four types of potassium currents in motor nerve terminals of snake

    Institute of Scientific and Technical Information of China (English)

    施玉樑; 顾琛; 徐幼芬

    1997-01-01

    The experiments were perfomed on transvcrsus abdominis muscle of Elaphe dione by subendothelial recording. The results indicate that in snake motor nerve endings there exist four types of K* channels, i.e. voltage-dependent fast and slow K+ channels, Ca2 +-activated K+ channel and ATP-sensitive K+ channel, (i) The typical wave form of snake terminal current was the double-peaked negativity in standard solution. The first peak was at-tributed to Na influx (INa) in nodes of Ranvier. The second one was blocked by 3, 4-aminopyridine (3, 4-DAP) or te-traethylammonium (TEA), which corresponded to fast K+ outward current (IKF) through the fast K* channels in terminal part, (ii) After IKF as well as the slow K+ current (IKS) were blocked by 3, 4-DAP, the TEA-sensitive Ca2+-dependent K+ current (IK(Ca)) passing through Ca2+-activated K+ channel was revealed, whose amplitude depended on [K+ ]and [Ca2+ ] It was blocked by Ba2+ , Cd2+ or Co2+ . (iii) IK.F and IK(Ca) were blocked by TEA, while IK.S was retained. It

  4. Experimental results of current distribution in Rutherford-type LHC cables

    CERN Document Server

    Verweij, A P

    2000-01-01

    Current distribution among the wires of multi-strand superconducting cables is an important item for accelerator magnets. A non-uniform distribution could cause additional field distortions in the magnet bore and can as well be one of the reasons of premature quenching. Since two years electrical measurements on superconducting Rutherford-type cables are performed at CERN as part of the reception tests for the Large Hadron Collider (LHC). Cable samples of 2.4 m length are tested at currents up to 32 kA, temperatures around 1.9 and 4.3 K, and fields up to 10 T, applied perpendicularly as well as parallel to the broad face of the cable. Last year, an array of 24 Hall probes was installed in the test set-up in order to measure the self-field of the cable samples along one cable pitch. Each of the probes measures the local field generated by the current in the strands close by, and the results of the all probes reflect therefore the distribution of the strand currents. Experiments are done varying the applied fie...

  5. A Novel Crowbar Impulse Current Circuit for Testing the Switch-Type SPD

    Institute of Scientific and Technical Information of China (English)

    YAO Xueling; CHEN Jingliang; SUN Wei

    2008-01-01

    A crowbar impulse current circuit for testing the switch-type surge protective device (SPD) is presented. The crowbar circuit consists of a computer control circuit, a trigger voltage pulse generator, a main discharging switch, and a crowbar pseudospark switch. The active trigger technology was studied in the crowbar impulse current circuit. The circuit monitors the main discharging current and generates a trigger signal at a proper time for the crowbar pseudospark switch operation. The trigger characteristics of the main discharge switch and the crowbar pseudospark switch were investigated. By monitoring the preset applied capacitor voltage, the gap distance of the main discharging switch could be adjusted to ensure a discharging delay time less than 2 μs. Equipped with a surface flashover trigger device made of high relative perimittivity dielectric material BaTiO3 (εr = 3460), the discharge delay time of the crowbar pseudospark switch is less than 85 ns, and the minimum operating voltage is less than 1% of its self-breakdown voltage. With a storage capacitor of 9 μF , an inductor of 18 μH and a crowbar pseudospark switch, a load of 30 mΩ and an applied capacitor voltage of 40 kV, an impulse current wave form of maximum 25 kA was generated with a rise time and time to half peak value of 17.2/μs and 336 μs respectively.

  6. $\\gamma$ and $\\upsilon$ distributions for neutral current reactions of the Weinberg- type

    CERN Document Server

    Albright, C H

    1974-01-01

    The y and v distributions for inclusive neutrino and antineutrino reactions arising from a neutral current of the Weinberg-type are investigated in the framework of two quark parton models. While the v distributions appear of little use at present, it is shown that by making a cut in the y variable, one can determine sin/sup 2/ theta /sub W/ reasonably accurately, independent of the cross section determination, even with the present narrow-band dichromatic neutrino beam at NAL. (18 refs).

  7. NEW TYPES INDEX OF ACCOUNTING [ALL THAT CURRENTLY EXIST IN THE WORLD

    OpenAIRE

    Valdivia Ramos, Román Arturo; Facultad de Ciencias Contables, Universidad Nacional Mayor de San Marcos

    2014-01-01

    In this research, it signals a new World Ranking types of accounting that currently exist in the world. We do not know a rating as extensive and detailed as the one presented, the product of a long academic research. This classification should be the foundation and / or support of further work to be carried or led by other researchers in the field. This is a rather unique classification, unlike anything known today. This is the contribution to the School of Accounting and makes the world acco...

  8. Barnidipine block of L-type Ca2+ channel currents in rat ventricular cardiomyocytes

    OpenAIRE

    Wegener, Jörg W.; Meyrer, Hans; Rupp, Johanna; Nawrath, Hermann

    2000-01-01

    The effects of barnidipine and nifedipine on L-type Ca2+ current (ICa(L)) were investigated in ventricular cardiomyocytes from rats.Both barnidipine and nifedipine reduced ICa(L) in a concentration and voltage dependent manner; the EC50 were 80 and 130 nM at a holding potential of −80 mV, respectively, and 18 and 6 nM at −40 mV, respectively.Both drugs induced a leftward shift of the steady-state inactivation curve of ICa(L).Using a twin pulse protocol, the relationships between the amount of...

  9. Analysis of induction-type coilgun performance based on cylindrical current sheet model

    Energy Technology Data Exchange (ETDEWEB)

    He, J.L.; Levi, E.; Zabar, Z.; Birenbaum, L.; Naot, Y. (Polytechnic Univ., Brooklyn, NY (United States))

    1991-01-01

    This paper presents a method based on a cylindrical current sheet model for the analysis and design of induction-type coilguns. The paper starts with a derivation of closed-form formulas which relate the dimensions of the gun to the performance expressed in terms of propulsive and local maximum forces on the projectile, power factor and efficiency of the system, thermal stress of the projectile armature, distributions of the flux density around the launcher, and the system parameters in a multisection coilgun. The paper ends with a numerical example.

  10. Analysis of induction-type coilgun performance based on cylindrical current sheet model

    Science.gov (United States)

    He, J. L.; Levi, E.; Zabar, Z.; Birenbaum, L.; Naot, Y.

    1991-01-01

    A method which is based on a cylindrical current sheet model for the analysis and design of induction-type coilguns is presented. The work starts with a derivation of closed-form formulas which relate the dimensions of the gun to the performance expressed in terms of propulsive and local maximum forces on the projectile, power factor and efficiency of the system, thermal stress of the projectile armature, distributions of the flux density around the launcher, and the system parameters in a multisection coilgun. A numerical example is given.

  11. Effect of current glycemic control on qualitative body composition in sedentary ambulatory Type 2 diabetics

    Directory of Open Access Journals (Sweden)

    Jayesh Dalpatbhai Solanki

    2016-01-01

    Full Text Available Background: Obesity and Type 2 diabetes mellitus are on rise with cause–effect relationship. Diabetics monitor blood sugar, neglecting qualitative body composition, leaving residual threat of ectopic fat unattended. We tried to correlate glycemic triad with parameters of body composition derived objectively by bioelectrical impedance analysis (BIA. Materials and Methods: A sample of 78 under treatment sedentary Type 2 diabetics of either sex with known glycemic and lipidemic control from our city. Following baseline assessment measurement was done by instrument Omron Karada Scan (Model HBF-510, China using the principle of tetra poplar BIA to derive parameters of body composition. We tried to correlate glycemic triad with these parameters, both directly as well as after defining them as per established cutoff norms. Results: We found poor glycemic control in the study group (20% for Hb1AC, high body mass index, subcutaneous fat, visceral fat (VF, total body fat (TBF, and lesser mass of skeletal muscle in Type 2 diabetics. However, there were small, insignificant, and inconsistent difference of these parameters while directly correlating with the fasting blood sugar, postprandial blood sugar, and glycosylated hemoglobin. On qualitative assessment, the impact of glycemic control as per standard norms, the risk of high VF, high TBF, low skeletal muscle mass was though high (between 1 and 2 in Type 2 diabetics with poor glycemic control as compared to good glycemics, but each strength lacks statistical significance. Conclusion: BIA reveals that Type 2 diabetics have more ectopic fat on expense of skeletal muscle that do not correlate with current glycemic status, both quantitatively and qualitatively. Measurement of body composition can be included and subjects can be motivated for lifestyle modification strategies while managing metabolic derangements of Type 2 diabetes.

  12. Weight management in type 2 diabetes: current and emerging approaches to treatment.

    Science.gov (United States)

    Van Gaal, Luc; Scheen, André

    2015-06-01

    Diabetes is a growing global health concern, as is obesity. Diabetes and obesity are intrinsically linked: obesity increases the risk of diabetes and also contributes to disease progression and cardiovascular disease. Although the benefits of weight loss in the prevention of diabetes and as a critical component of managing the condition are well established, weight reduction remains challenging for individuals with type 2 diabetes due to a host of metabolic and psychological factors. For many patients, lifestyle intervention is not enough to achieve weight loss, and alternative options, such as pharmacotherapy, need to be considered. However, many traditional glucose-lowering medications may lead to weight gain. This article focuses on the potential of currently available pharmacological strategies and on emerging approaches in development to support the glycemic and weight-loss goals of individuals with type 2 diabetes. Two pharmacotherapy types are considered: those developed primarily for blood glucose control that have a favorable effect on body weight and those developed primarily to induce weight loss that have a favorable effect on blood glucose control. Finally, the potential of combination therapies for the management of obese patients with type 2 diabetes is discussed.

  13. Cardiac effects of 3 months treatment of acromegaly evaluated by magnetic resonance imaging and B-type natriuretic peptides

    DEFF Research Database (Denmark)

    Andreassen, Mikkel; Faber, Jens; Kjær, Andreas;

    2010-01-01

    of acromegaly is initiated. This was a three months prospective study investigating short-term cardiac effects of treatment in acromegalic patients. Cardiac function was evaluated by the gold standard method cardiac magnetic resonance imaging (CMRI) and circulating levels of B-type natriuretic peptides (BNP......Long-term treatment of acromegaly prevents aggravation and reverses associated heart disease. A previous study has shown a temporary increase in serum levels of the N-terminal fraction of pro B-type natriuretic peptide (NT-proBNP) suggesting an initial decline in cardiac function when treatment...... and NT-proBNP). CMRI was performed at baseline and after 3 months of treatment. Levels of IGF-I, BNP and NT-proBNP were measured after 0, 1, 2 and 3 months. Eight patients (5 males and 3 females, mean age 53 ± 12 years (range 30-70)) and 8 matched healthy control subjects were included. Median IGF-I Z...

  14. Electric and Magnetic properties Computed for Valence Bond Structures: Is There a Link between Pauling Resonance Energy and Ring Current?

    NARCIS (Netherlands)

    Havenith, R.W.A.

    2006-01-01

    To establish the link between the aromaticity descriptors based on the Pauling resonance energy and the molecular properties, the electric (polarizability) and magnetic (magnetizability) field response properties haven been calculated using the valence bond approach for various molecules and their i

  15. A wave guide model of lightning currents and their electromagnetic field

    Science.gov (United States)

    Volland, H.

    1980-01-01

    Lightning channels are considered as resonant wave guides in which only standing resonant wave modes can be excited. Two types of discharging currents develop. Type 1 is an aperiodic wave; type 2 is a damped oscillation. The electromagnetic radiation field of both types of currents is calculated and compared with the observation.

  16. Development of a surface plasmon resonance biosensing approach for the rapid detection of porcine circovirus type2 in sample solutions.

    Directory of Open Access Journals (Sweden)

    Jiandong Hu

    Full Text Available A sensitive and label-free analytical approach for the detection of porcine circovirus type 2 (PCV2 instead of PCV2 antibody in serum sample was systematically investigated in this research based on surface plasmon resonance (SPR with an establishment of special molecular identification membrane. The experimental device for constructing the biosensing analyzer is composed of an integrated biosensor, a home-made microfluidic module, and an electrical control circuit incorporated with a photoelectric converter. In order to detect the PCV2 using the surface plasmon resonance immunoassay, the mercaptopropionic acid has been used to bind the Au film in advance through the known form of the strong S-Au covalent bonds formed by the chemical radical of the mercaptopropionic acid and the Au film. PCV2 antibodies were bonded with the mercaptopropionic acid by covalent -CO-NH- amide bonding. For the purpose of evaluating the performance of this approach, the known concentrations of PCV2 Cap protein of 10 µg/mL, 7.5 µg/mL, 5 µg/mL, 2.5 µg/mL, 1 µg/mL, and 0.5 µg/mL were prepared by diluting with PBS successively and then the delta response units (ΔRUs were measured individually. Using the data collected from the linear CCD array, the ΔRUs gave a linear response over a wide concentration range of standard known concentrations of PCV2 Cap protein with the R-Squared value of 0.99625. The theoretical limit of detection was calculated to be 0.04 µg/mL for the surface plasmon resonance biosensing approach. Correspondingly, the recovery rate ranged from 81.0% to 89.3% was obtained. In contrast to the PCV2 detection kits, this surface plasmon resonance biosensing system was validated through linearity, precision and recovery, which demonstrated that the surface plasmon resonance immunoassay is reliable and robust. It was concluded that the detection method which is associated with biomembrane properties is expected to contribute much to determine the PCV2

  17. Development of a surface plasmon resonance biosensing approach for the rapid detection of porcine circovirus type2 in sample solutions.

    Science.gov (United States)

    Hu, Jiandong; Wang, Tingting; Wang, Shun; Chen, Mingwen; Wang, Manping; Mu, Linying; Chen, Hongyin; Hu, Xinran; Liang, Hao; Zhu, Juanhua; Jiang, Min

    2014-01-01

    A sensitive and label-free analytical approach for the detection of porcine circovirus type 2 (PCV2) instead of PCV2 antibody in serum sample was systematically investigated in this research based on surface plasmon resonance (SPR) with an establishment of special molecular identification membrane. The experimental device for constructing the biosensing analyzer is composed of an integrated biosensor, a home-made microfluidic module, and an electrical control circuit incorporated with a photoelectric converter. In order to detect the PCV2 using the surface plasmon resonance immunoassay, the mercaptopropionic acid has been used to bind the Au film in advance through the known form of the strong S-Au covalent bonds formed by the chemical radical of the mercaptopropionic acid and the Au film. PCV2 antibodies were bonded with the mercaptopropionic acid by covalent -CO-NH- amide bonding. For the purpose of evaluating the performance of this approach, the known concentrations of PCV2 Cap protein of 10 µg/mL, 7.5 µg/mL, 5 µg/mL, 2.5 µg/mL, 1 µg/mL, and 0.5 µg/mL were prepared by diluting with PBS successively and then the delta response units (ΔRUs) were measured individually. Using the data collected from the linear CCD array, the ΔRUs gave a linear response over a wide concentration range of standard known concentrations of PCV2 Cap protein with the R-Squared value of 0.99625. The theoretical limit of detection was calculated to be 0.04 µg/mL for the surface plasmon resonance biosensing approach. Correspondingly, the recovery rate ranged from 81.0% to 89.3% was obtained. In contrast to the PCV2 detection kits, this surface plasmon resonance biosensing system was validated through linearity, precision and recovery, which demonstrated that the surface plasmon resonance immunoassay is reliable and robust. It was concluded that the detection method which is associated with biomembrane properties is expected to contribute much to determine the PCV2 in sample

  18. High peak-to-valley current ratio In0.53Ga0.47As/AlAs resonant tunneling diode with a high doping emitter

    Institute of Scientific and Technical Information of China (English)

    Wang Wei; Sun Hao; Teng Teng; Sun Xiaowei

    2012-01-01

    An In0.53Ga0.47As/AlAs resonant tunneling diode (RTD) with a high doping emitter is designed and fabricated using air bridge technology.The RTD exhibits a high peak-to-valley current ratio (PVCR) of more than 40 at room temperature,with a peak current density of 24 kA/cm2.The extraction of device parameters from DC and microwave measurements is presented together with an RTD equivalent circuit.The high PVCR RTD with small intrinsic capacitance is favorable for microwave/THz applications.

  19. Current Status of Prescription in Type 2 Diabetic Patients from General Hospitals in Busan

    Directory of Open Access Journals (Sweden)

    Ji Hye Suk

    2014-06-01

    Full Text Available BackgroundData regarding the prescription status of individuals with diabetes are limited. This study was an analysis of participants from the relationship between cardiovascular disease and brachial-ankle pulse wave velocity in patients with type 2 diabetes (REBOUND Study, which was a prospective multicenter cohort study recruited from eight general hospitals in Busan, Korea. We performed this study to investigate the current status of prescription in Korean type 2 diabetic patients.MethodsType 2 diabetic patients aged 30 years or more were recruited and data were collected for demographics, medical history, medications, blood pressure, and laboratory tests.ResultsThree thousands and fifty-eight type 2 diabetic patients were recruited. Mean age, duration of diabetes, and HbA1c were 59 years, 7.6 years, and 7.2%, respectively. Prevalence of hypertension was 66%. Overall, 7.3% of patients were treated with diet and exercise only, 68.2% with oral hypoglycemic agents (OHAs only, 5.3% with insulin only, and 19.2% with both insulin and OHA. The percentage of patients using antihypertensive, antidyslipidemic, antiplatelet agents was similar as about 60%. The prevalence of statins and aspirin users was 52% and 32%, respectively.ConclusionIn our study, two thirds of type 2 diabetic patients were treated with OHA only, and one fifth with insulin plus OHA, and 5% with insulin only. More than half of the patients were using each of antihypertensive, antidyslipidemic, or antiplatelet agents. About a half of the patients were treated with statins and one third were treated with aspirin.

  20. Current status of bariatric surgery in the treatment of type 2 diabetes.

    Science.gov (United States)

    Pinkney, J; Kerrigan, D

    2004-02-01

    Bariatric surgery (from the Greek words baros meaning 'weight' and iatrikos 'the art of healing') is a rapidly evolving branch of surgical science. The aim is to induce major weight loss in those whose obesity places them at high risk of serious health problems. In an attempt to balance the risks of surgery against the benefits of weight loss, bariatric operations are currently performed only in the morbidly obese, or those with a body mass index (BMI) > 35 kgm(-2) who already have developed comorbidity such as type 2 diabetes. Although weight loss is beneficial for obese patients with diabetes, current medical treatment for obesity is difficult. In contrast, observational studies show a major impact of bariatric surgery on diabetes, raising the question whether this approach should be used more widely to treat diabetes in obese patients? If bariatric surgery were shown to be the best way to treat diabetes in obese subjects the implications for health services would be wide-ranging. Bariatric surgery leads to withdrawal of diabetic treatment in about 60% or more of patients, and reductions of therapy for many others. Although data on bariatric surgery in subjects with diabetes are provocative, most studies have been uncontrolled or flawed in other ways. Most importantly, bariatric surgery has not yet been compared against standard medical treatment for diabetes in randomized controlled trials with diabetes-specific endpoints in all relevant patient groups. Potential indications for bariatric surgery are discussed, and the unanswered questions that need to be addressed by clinical trials are summarized. Although small numbers of patients may be interested in bariatric surgery for type 2 diabetes, current data are insufficient to endorse its wide scale use for this indication. Until essential studies are undertaken the role and economics of bariatric surgery in the diabetic clinic will remain uncertain.

  1. Dixon-type and subtraction-type contrast-enhanced magnetic resonance angiography: A theoretical and experimental comparison of SNR and CNR.

    Science.gov (United States)

    Stinson, Eric G; Trzasko, Joshua D; Weavers, Paul T; Riederer, Stephen J

    2014-07-17

    The purpose of this work is to compare the behavior of the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in contrast-enhanced MR angiography with background suppression performed by either a Dixon-type or subtraction-type method. Theoretical expressions for the SNR and CNR for both background suppression techniques were derived. The theoretical Dixon:subtraction SNR and CNR ratios were compared to empirical ratios measured from phantom and in vivo studies for Dixon techniques utilizing one, two, and three echoes. Specifically, the SNR and CNR ratios were compared as the concentration of contrast material in the blood changed. Empirical measurements of the SNR and CNR ratios compared favorably with the ratios predicted by theory. As the contrast concentration was reduced, the SNR advantage of the Dixon techniques increased asymptotically. In the ideal case, the SNR improvement over subtraction contrast-enhanced MR angiography was at least twofold for one- and two-echo Dixon techniques and at least a factor of 6 for the three-echo Dixon technique. Expressions showing a contrast concentration-dependent SNR and CNR improvement of at least a factor of two when Dixon-type contrast-enhanced MR angiography is used in place of subtraction-type contrast-enhanced MR angiography were derived and validated with phantom and in vivo experiments. Magn Reson Med, 2014. © 2014 Wiley Periodicals, Inc. Copyright © 2014 Wiley Periodicals, Inc.

  2. Cardioprotective effects of 5-hydroxymethylfurfural mediated by inhibition of L-type Ca(2+) current.

    Science.gov (United States)

    Wölkart, G; Schrammel, A; Koyani, C N; Scherübel, S; Zorn-Pauly, K; Malle, E; Pelzmann, B; Andrä, M; Ortner, A; Mayer, B

    2017-08-02

    The antioxidant 5-hydroxymethylfurfural (5-HMF) exerts documented beneficial effects in several experimental pathologies and is currently tested as antisickling drug in clinical trials. In the present study we examined the cardiovascular effects of 5-HMF and elucidated the mode of action of the drug. The cardiovascular effects of 5-HMF were studied with precontracted porcine coronary arteries and isolated normoxic perfused rat hearts. Isolated hearts subjected to ischemia/reperfusion (I/R) injury were used to test for potential cardioprotective effects of the drug. The effects of 5-HMF on action potential (AP) and L-type Ca(2+) current (ICa,L ) were studied by patch-clamping isolated guinea pig ventricular cardiomyocytes. 5-HMF relaxed coronary arteries in a concentration-dependent manner and exerted negative inotropic, lusitropic and chronotropic effects in isolated perfused rat hearts. On the other hand, 5-HMF improved recovery of inotropic and lusitropic parameters in isolated hearts subjected to I/R. Patch clamp experiments revealed that 5-HMF inhibits L-type Ca(2+) channels. Reduced ICa,L density, shift of ICa,L steady state inactivation curves toward negative membrane potentials and slower recovery of ICa,L from inactivation in response to 5-HMF accounted for the observed cardiovascular effects. Our data revealed a cardioprotective effect of 5-HMF in I/R that is mediated by inhibition of L-type Ca(2+) channels. Thus, 5-HMF is suggested as beneficial additive to cardioplegic solutions, but adverse effects and contraindications of Ca(2+) channel blockers have to be considered in therapeutic application of the drug. This article is protected by copyright. All rights reserved.

  3. Impact of Current and Emerging Glucose-Lowering Drugs on Body Weight in Type 2 Diabetes.

    Science.gov (United States)

    Lau, David C W; Teoh, Hwee

    2015-12-01

    Type 2 diabetes is a progressive disease, and most people with diabetes will eventually require adjunctive pharmacotherapy to optimize their glycemic control. As the majority of people with type 2 diabetes are overweight or obese, weight management is an essential component of diabetes management to improve their overall health and quality of life. Many of the currently available glucose-lowering drugs are associated with weight gain, which makes it challenging for both prescribing clinicians and patients. The 2015 Canadian Diabetes Association Clinical Practice Guidelines interim update on the pharmacologic management of type 2 diabetes recommend individualization of therapy and glycemic targets. Clinicians should take into consideration not only the drug's efficacy and safety profiles but also its propensity for causing hypoglycemia and weight gain. Given that the number of glucose-lowering drugs is expanding rapidly, a better understanding of the impacts of current and emerging therapies on body weight will serve as a useful guide. Metformin remains the first-line drug after diet and exercise therapy. The next add-on agent could be selected from the incretin or sodium-glucose cotransporter-2 inhibitor class because these drugs rarely cause hypoglycemia and may lead to modest weight loss. When insulin therapy is considered, choosing a basal insulin that is associated with less nocturnal hypoglycemia and weight gain is recommended. Emerging therapies using combination therapy of an incretin-sodium-glucose cotransporter 2 inhibitor or glucagon-like peptide-1 agonist-basal insulin hold promise to achieve robust glycemic control with weight loss and low risk for hypoglycemia.

  4. The Measuring and Protection Method for the Abnormal Rise of Magnetizing Inrush Current in a Divided Type 3 CTs System

    Science.gov (United States)

    Iwasaki, Fumio; Ibe, Masayuki; Ninohei, Koichiro; Okamura, Seichiro

    This paper describes the measuring and protection method for the abnormal rise of magnetizing inrush current in a divided type 3 CTs system. By divided type 3 CTs system, it is possible to measure the primary phase current and zero phase current at the same time. In this reason, the divided type 3 CTs system is widely used for the measurement of high voltage distribution line by simply clamping the each phase lines with 3CTs. For the accurate measurement of the phase current and zero phase current, the internal residual current in CT should be small as possible. It is reported that the abnormal rise of the residual current is generated in the practical field use and several ten ampere (converted to the primary current value) is observed in some case. The abnormal rise of the residual current is caused by the primary magnetizing inrush current or by the sum of the influence by electromagnetic field of the nearby conductors. The magnetizing inrush current is caused by the magnetic saturation of the core of CT. It is difficult to eliminate the abnormal residual current by using the bigger size of core. In our test, we used the active elements and independent feed back coils around the right and left core of CT. By using the feed back current from these coils it was observed that the magnetic saturation of the core is improved and the magnetizing inrush current can be controlled.

  5. Dynamic Evaluation of LCL-type Grid-Connected Inverters with Different Current Feedback Control Schemes

    DEFF Research Database (Denmark)

    Han, Yang; Li, Zipeng; Guerrero, Josep M.

    2015-01-01

    Proportional-resonant (PR) compensator and LCL filter becomes a better choice in grid-connected inverter system with high performance and low costs. However, the resonance phenomenon caused by LCL filter affect the system stability significantly. In this paper, the stability problem of three...... of the controller and filter with different feedback configurations are provided. The impacts of digital delay, PR parameters and LCL parameters on different control strategies are also investigated. Finally, the theoretical analysis are validated by simulation results....

  6. Structural mapping of divergent regions in the type 1 ryanodine receptor using fluorescence resonance energy transfer.

    Science.gov (United States)

    Mahalingam, Mohana; Girgenrath, Tanya; Svensson, Bengt; Thomas, David D; Cornea, Razvan L; Fessenden, James D

    2014-09-02

    Ryanodine receptors (RyRs) release Ca(2+) to initiate striated muscle contraction. Three highly divergent regions (DRs) in the RyR protein sequence (DR1, DR2, and DR3) may confer isoform-specific functional properties to the RyRs. We used cell-based fluorescence resonance energy transfer (FRET) measurements to localize these DRs to the cryoelectron microscopic (cryo-EM) map of the skeletal muscle RyR isoform (RyR1). FRET donors were targeted to RyR1 using five different FKBP12.6 variants labeled with Alexa Fluor 488. FRET was then measured to the FRET acceptors, Cy3NTA or Cy5NTA, targeted to decahistidine tags introduced within the DRs. DR2 and DR3 were localized to separate positions within the "clamp" region of the RyR1 cryo-EM map, which is presumed to interface with Cav1.1. DR1 was localized to the "handle" region, near the regulatory calmodulin-binding site on the RyR. These localizations provide insights into the roles of DRs in RyR allosteric regulation during excitation contraction coupling. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Inhibition of K+ currents in type I vestibular hair cells by gentamicin and neomycin.

    Science.gov (United States)

    Mann, Scott E; Johnson, Matthew; Meredith, Frances L; Rennie, Katherine J

    2013-01-01

    Significant ototoxicity limits the use of aminoglycoside (AG) antibiotics. Several mechanisms may contribute to the death of both auditory and vestibular hair cells. In this study the effects of gentamicin and neomycin on K(+) currents in mature and early postnatal type I vestibular hair cells (HCI) were tested directly. The whole-cell patch clamp technique was used to assess the effects of AG and KCNQ channel modulators on K(+) currents (IK) in HCI acutely isolated from gerbil semicircular canals. Extracellular neomycin (1 mM) rapidly reduced peak outward IK by 16 ± 4% (n = 9) in mature HCI (postnatal days, P, 25-66). Gentamicin (5 mM) reduced outward IK by 16 ± 3% (n = 8). A similar reduction in outward current was seen in immature HCI (P5-9) that lacked the low-voltage-activated component of IK observed in mature cells. Intracellular application of gentamicin and neomycin also reduced IK in mature HCI. Modulators of KCNQ channels were used to probe KCNQ channel involvement. The selective KCNQ antagonist XE991 did not reduce IK and the neomycin-induced reduction in IK was not reversed by the KCNQ agonist flupirtine. Application of intracellular poly-D-lysine to sequester PIP2 did not reduce IK. Application of the K(+) channel blocker 4-aminopyridine (4-AP) strongly reduced IK, and extracellular AG in the presence of 4-AP gave no further inhibition of IK. In summary, AG significantly reduce the 4-AP-sensitive IK in early postnatal and mature HCI. K(+) current inhibition differs from that seen in outer hair cells, since it does not appear to involve PIP2 sequestration or KCNQ channels.

  8. T-type Ca2+ current activity during oocyte growth and maturation in the ascidian Styela plicata.

    Directory of Open Access Journals (Sweden)

    Alessandra Gallo

    Full Text Available Voltage-dependent calcium currents play a fundamental role during oocyte maturation, mostly L-type calcium currents, whereas T-type calcium currents are involved in sperm physiology and cell growth. In this paper, using an electrophysiological and pharmacological approach, we demonstrated, for the first time in oocytes, that T-type calcium currents are present with functional consequences on the plasma membrane of growing immature oocytes of the ascidian Styela plicata. We classified three subtypes of immature oocytes at the germinal vesicle stage on the basis of their size, morphology and accessory cellular structures. These stages were clearly associated with an increased activity of T-type calcium currents and hyperpolarization of the plasma membrane. We also observed that T-type calcium currents oscillate in the post-fertilization embryonic stages, with minimal amplitude of the currents in the zygote and maximal at 8-cell stage. In addition, chemical inhibition of T-type calcium currents, obtained by applying specific antagonists, induced a significant reduction in the rate of cleavage and absence of larval formation. We suggest that calcium entry via T-type calcium channels may act as a potential pacemaker in regulating cytosolic calcium involved in fertilization and early developmental events.

  9. Development of a resonant-type microwave reactor and its application to the synthesis of positron emission tomography radiopharmaceuticals.

    Science.gov (United States)

    Kimura, Hiroyuki; Yagi, Yusuke; Ohneda, Noriyuki; Odajima, Hiro; Ono, Masahiro; Saji, Hideo

    2014-10-01

    Microwave technology has been successfully applied to enhance the effectiveness of radiolabeling reactions. The use of a microwave as a source of heat energy can allow chemical reactions to proceed over much shorter reaction times and in higher yields than they would do under conventional thermal conditions. A microwave reactor developed by Resonance Instrument Inc. (Model 520/521) and CEM (PETWave) has been used exclusively for the synthesis of radiolabeled agents for positron emission tomography by numerous groups throughout the world. In this study, we have developed a novel resonant-type microwave reactor powered by a solid-state device and confirmed that this system can focus microwave power on a small amount of reaction solution. Furthermore, we have demonstrated the rapid and facile radiosynthesis of 16α-[(18)F]fluoroestradiol, 4-[(18)F]fluoro-N-[2-(1-methoxyphenyl)-1-piperazinyl]ethyl-N-2-pyridinylbenzamide, and N-succinimidyl 4-[(18)F]fluorobenzoate using our newly developed microwave reactor.

  10. Neutron absorbers and detector types for spent fuel verification using the self-interrogation neutron resonance densitometry

    Energy Technology Data Exchange (ETDEWEB)

    Rossa, Riccardo, E-mail: rrossa@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium); Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Borella, Alessandro, E-mail: aborella@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium); Labeau, Pierre-Etienne, E-mail: pelabeau@ulb.ac.be [Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Pauly, Nicolas, E-mail: nipauly@ulb.ac.be [Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Meer, Klaas van der, E-mail: kvdmeer@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium)

    2015-08-11

    The Self-Interrogation Neutron Resonance Densitometry (SINRD) is a passive non-destructive assay (NDA) technique that is proposed for the direct measurement of {sup 239}Pu in a spent fuel assembly. The insertion of neutron detectors wrapped with different neutron absorbing materials, or neutron filters, in the central guide tube of a PWR fuel assembly is envisaged to measure the neutron flux in the energy region close to the 0.3 eV resonance of {sup 239}Pu. In addition, the measurement of the fast neutron flux is foreseen. This paper is focused on the determination of the Gd and Cd neutron filters thickness to maximize the detection of neutrons within the resonance region. Moreover, several detector types are compared to identify the optimal condition and to assess the expected total neutron counts that can be obtained with the SINRD measurements. Results from Monte Carlo simulations showed that ranges between 0.1–0.3 mm and 0.5–1.0 mm ensure the optimal conditions for the Gd and Cd filters, respectively. Moreover, a {sup 239}Pu fission chamber is better suited to measure neutrons close to the 0.3 eV resonance and it has the highest sensitivity to {sup 239}Pu, in comparison with a {sup 235}U fission chamber, with a {sup 3}He proportional counter, and with a {sup 10}B proportional counter. The use of a thin Gd filter and a thick Cd filter is suggested for the {sup 239}Pu and {sup 235}U fission chambers to increase the total counts achieved in a measurement, while a thick Gd filter and a thin Cd filter are envisaged for the {sup 3}He and {sup 10}B proportional counters to increase the sensitivity to {sup 239}Pu. We concluded that an optimization process that takes into account measurement time, filters thickness, and detector size is needed to develop a SINRD detector that can meet the requirement for an efficient verification of spent fuel assemblies.

  11. Current issues in GLP-1 receptor agonist therapy for type 2 diabetes.

    Science.gov (United States)

    Bloomgarden, Zachary T; Blonde, Lawrence; Garber, Alan J; Wysham, Carol H

    2012-01-01

    The clinical management of hyperglycemia in patients with type 2 diabetes mellitus (T2DM) is guided not only by published treatment algorithms, but also by consideration of recent evidence and through consultation with colleagues and experts. Recent studies have dramatically increased the amount of information regarding the use of glucagon-like peptide-1 receptor agonists (GLP-1 RAs). Topics that may be of particular interest to clinicians who treat T2DM patients include relative glycemic control efficacy of GLP-1 RAs, use of GLP-1 RAs across T2DM progression and in combination with insulin, recent data regarding GLP-1 RA safety, nonglycemic actions of GLP-1 RAs, including weight effects, and impact of GLP-1 RAs on patient quality of life and treatment satisfaction. The following review includes expert consideration of these topics with emphasis on recent, relevant reports to illustrate current perspectives.

  12. Investigation of the cerebral energy status in patients with glutaric aciduria type I by 31P magnetic resonance spectroscopy.

    Science.gov (United States)

    Möller, H E; Koch, H G; Weglage, J; Freudenberg, F; Ullrich, K

    2003-04-01

    In vivo phosphorus magnetic resonance spectroscopy (MRS) was used to investigate markers of the cerebral energy status in two patients with glutaric aciduria type I (GA-I). Besides an increased concentration of phosphomonoesters in one patient, no other significant alterations from controls were found. This might indicate increased resynthesis of dendritic processes secondary to preceding metabolic crises. In contrast to previous cell-culture studies, no cerebral depletion of phosphocreatine (PCr) was observed. In conclusion, a severe global and permanent depletion of cerebral energy supplies must be ruled out. The benefit of a permanent creatine substitution to stabilize mitochondrial energy metabolism seems thus questionable. However, as MRS was performed during stable clinical conditions, the possibility of a PCr decrease during acute metabolic crises cannot be assessed.

  13. Comparison effects and electron spin resonance studies of α-Fe2O4 spinel type ferrite nanoparticles.

    Science.gov (United States)

    Bayrakdar, H; Yalçın, O; Cengiz, U; Özüm, S; Anigi, E; Topel, O

    2014-11-11

    α-Fe2O4 spinel type ferrite nanoparticles have been synthesized by cetyltrimethylammonium bromide (CTAB) and ethylenediaminetetraacetic acid (EDTA) assisted hydrothermal route by using NaOH solution. Electron spin resonance (ESR/EPR) measurements of α-Fe2O4 nanoparticles have been performed by a conventional x-band spectrometer at room temperature. The comparison effect of nanoparticles prepared by using CTAB and EDTA in different α-doping on the structural and morphological properties have been investigated in detail. The effect of EDTA-assisted synthesis for α-Fe2O4 nanoparticles are refined, and thus the spectroscopic g-factor are detected by using ESR signals. These samples can be considered as great benefits for magnetic recording media, electromagnetic and drug delivery applications.

  14. Temporal Bell-type inequalities for two-level Rydberg atoms coupled to a high-{ital Q} resonator

    Energy Technology Data Exchange (ETDEWEB)

    Huelga, S.F.; Marshall, T.W.; Santos, E. [Departamento de Fisica, Universidad de Oviedo, 33007 Oviedo (Spain)]|[Department of Mathematics, University of Manchester, Manchester M139PL, United Kingdom Departamento de Fisica Moderna, Universidad de Cantabria, 39005 Santander (Spain)

    1996-09-01

    Following the strategy of showing specific quantum effects by means of the violation of a classical inequality, a pair of Bell-type inequalities is derived on the basis of certain additional assumptions, whose plausibility is discussed in detail. Such inequalities are violated by the quantum mechanical predictions for the interaction of a two-level Rydberg atom with a single mode sustained by a high-{ital Q} resonator. The experimental conditions required in order to show the existence of forbidden values, according to a hidden variables formalism, in a real experiment are analyzed for various initial field statistics. In particular, the revival dynamics expected for the interaction with a coherent field leads to classically forbidden values, which would indicate a purely quantum effect. {copyright} {ital 1996 The American Physical Society.}

  15. Spontaneous Involution of a Non-Optic Astrocytoma in Neurofibromatosis Type I: Serial Magnetic Resonance Imaging Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Cakirer, S. [Istanbul Sisli Etfal Hospital (Turkey). Dept. of Radiology; Karaarslan, E. [VKV American Hospital, Istanbul (Turkey). Dept. of Radiology

    2004-10-01

    A patient with neurofibromatosis type I (NF1) was followed-up with serial magnetic resonance imaging (MRI) studies over a period of 6 years. A contrast-enhancing lesion of the internal capsule, histologically proven to be pilocytic astrocytoma through stereotactic brain biopsy with mass effect and associated edema, was detected to reveal spontaneous involution on follow-up MRI studies. Although spontaneous regression of gliomas of the optic pathway-hypothalamus in patients with NF1 is relatively common in the literature, spontaneous involution of non-optic (i.e. areas other than optic pathways and hypothalamus) gliomas is rarely reported. Conservative management with follow-up MRI studies should be considered for non-optic glial tumors and tumor-like masses in patients with NF1, and surgical treatment should not be considered unless the lesions exhibit a rapid or unrelenting growth on serial MRI studies or produce significant clinical deterioration.

  16. Copernicus observations of the N v resonance doublet in 53 early-type stars

    Science.gov (United States)

    Abbott, D. C.; Bohlin, R. C.; Savage, B. D.

    1982-01-01

    UV spectra in the wavelength interval 1170-1270 A are presented for 53 early-type stars ranging in spectral type from O6.5 V to B2.5 IV. The sample includes four Wolf-Rayet stars, seven known Oe-Be stars, and six galactic halo OB stars. A qualitative analysis of the stellar N v doublet reveals that: (1) N v is present in all stars hotter and more luminous than type B0 for the main sequence, B1 for giants, and B2 for supergiants; (2) shell components of N v and an unidentified absorption feature at 1230 A are present in about half of the stars; (3) the column density of N v is well correlated with bolometric luminosity over the spectral range O6 to B2; and (4) the ratio of emission to absorption equivalent width is a factor of 2 smaller in the main sequence stars than in supergiants, which suggests that the wind structure changes as a star evolves. For several stars, this ratio is too small to be explained by traditional wind models.

  17. Current and emerging quantitative magnetic resonance imaging methods for assessing and predicting the response of breast cancer to neoadjuvant therapy

    Directory of Open Access Journals (Sweden)

    Abramson RG

    2012-10-01

    Full Text Available Richard G Abramson,1,2,9 Lori R Arlinghaus,1,2 Jared A Weis,1,2 Xia Li,1,2 Adrienne N Dula,1,2 Eduard Y Chekmenev,1–4,9 Seth A Smith,1–3,5 Michael I Miga,1–3,6 Vandana G Abramson,7,9 Thomas E Yankeelov1–3,5,8,91Institute of Imaging Science, 2Department of Radiology and Radiological Sciences, 3Department of Biomedical Engineering, 4Department of Biochemistry, 5Department of Physics, 6Department of Neurosurgery, 7Department of Medical Oncology, 8Department of Cancer Biology, 9Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville,TN, USAAbstract: Reliable early assessment of breast cancer response to neoadjuvant therapy (NAT would provide considerable benefit to patient care and ongoing research efforts, and demand for accurate and noninvasive early-response biomarkers is likely to increase. Response assessment techniques derived from quantitative magnetic resonance imaging (MRI hold great potential for integration into treatment algorithms and clinical trials. Quantitative MRI techniques already available for assessing breast cancer response to neoadjuvant therapy include lesion size measurement, dynamic contrast-enhanced MRI, diffusion-weighted MRI, and proton magnetic resonance spectroscopy. Emerging yet promising techniques include magnetization transfer MRI, chemical exchange saturation transfer MRI, magnetic resonance elastography, and hyperpolarized MR. Translating and incorporating these techniques into the clinical setting will require close attention to statistical validation methods, standardization and reproducibility of technique, and scanning protocol design.Keywords: treatment response, presurgical treatment, neoadjuvant chemotherapy

  18. Effects of KCNQ2 gene truncation on M-type Kv7 potassium currents.

    Directory of Open Access Journals (Sweden)

    Jon Robbins

    Full Text Available The KCNQ2 gene product, Kv7.2, is a subunit of the M-channel, a low-threshold voltage-gated K(+ channel that regulates mammalian and human neuronal excitability. Spontaneous mutations one of the KCNQ2 genes cause disorders of neural excitability such as Benign Familial Neonatal Seizures. However there appear to be no reports in which both human KCNQ2 genes are mutated. We therefore asked what happens to M-channel function when both KCNQ2 genes are disrupted. We addressed this using sympathetic neurons isolated from mice in which the KCNQ2 gene was truncated at a position corresponding to the second transmembrane domain of the Kv7.2 protein. Since homozygote KCNQ2-/- mice die postnatally, experiments were largely restricted to neurons from late embryos. Quantitative PCR revealed an absence of KCNQ2 mRNA in ganglia from KCNQ2-/- embryos but 100-120% increase of KCNQ3 and KCNQ5 mRNAs; KCNQ2+/- ganglia showed ∼30% less KCNQ2 mRNA than wild-type (+/+ ganglia but 40-50% more KCNQ3 and KCNQ5 mRNA. Neurons from KCNQ2-/- embryos showed a complete absence of M-current, even after applying the Kv7 channel enhancer, retigabine. Neurons from heterozygote KCNQ2+/- embryos had ∼60% reduced M-current. In contrast, M-currents in neurons from adult KCNQ2+/- mice were no smaller than those in neurons from wild-type mice. Measurements of tetraethylammonium block did not indicate an increased expression of Kv7.5-containing subunits, implying a compensatory increase in Kv7.2 expression from the remaining KCNQ2 gene. We conclude that mouse embryonic M-channels have an absolute requirement for Kv7.2 subunits for functionality, that the reduced M-channel activity in heterozygote KCNQ2+/- mouse embryos results primarily from a gene-dosage effect, and that there is a compensatory increase in Kv7.2 expression in adult mice.

  19. Effect of resveratrol on L-type calcium current in rat ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    Li-ping ZHANG; Jing-xiang YIN; Zheng LIU; Yi ZHANG; Qing-shan WANG; Juan ZHAO

    2006-01-01

    Aim: To study the effect of resveratrol on L-type calcium current (ICa-L) in isolated rat ventricular myocytes and the mechanisms underlying these effects. Methods:ICa-L was examined in isolated single rat ventricular myocytes by using the whole cell patch-clamp recording technique. Results: Resveratrol (10-40 μmol/L) reduced the peak amplitude of ICa-L and shifted the current-voltage (I-V) curve upwards in a concentration-dependent manner. Resveratrol (10, 20, 40 μmol/L)decreased the peak amplitude of ICa-L from -14.2± 1.5 pA/pF to -10.5± 1.5 pA/pF (P<0.05), -7.5±2.4 pA/pF (P<0.01), and -5.2±1.2 pA/pF (P<0.01), respectively.Resveratrol (40 μmol/L) shifted the steady-state activation curve of ICa-L to the right and changed the half-activation potential (V0.5) from -19.4±0.4 mV to -15.4±1.9 mV (P<0.05). Resveratrol at a concentration of 40 μmol/L did not affect the steady-state inactivation curve of ICa-L, but did markedly shift the timedependent recovery curve of ICa-L to the right, and slow down the recovery of ICa-L from inactivation. Sodium orthovanadate (Na3VO4; 1 mmol/L), a potent inhibitor of tyrosine phosphatase, significantly inhibited the effects of resveratrol (P<0.01). Conclusion: Resveratrol inhibited ICa- L mainly by inhibiting the activation of L-type calcium channels and slowing down the recovery of L-type calcium channels from inactivation. This inhibitory effect of resveratrol was mediated by the inhibition of protein tyrosine kinase in rat ventricular myocytes.

  20. Understanding and modeling Förster-type resonance energy transfer (FRET)

    CERN Document Server

    Hernández Martínez, Pedro Ludwig; Demir, Hilmi Volkan

    2017-01-01

    This Brief presents a complete study of the generalized theory of Förster-type energy transfer in nanostructures with mixed dimensionality. Here the aim is to obtain a generalized theory of FRET including a comprehensive set of analytical equations for all combinations and configurations of nanostructures and deriving generic expressions for the dimensionality involved. In this brief, the modification of FRET mechanism with respect to the nanostructure serving as the donor vs. the acceptor will be included, focusing on the rate’s distance dependency and the role of the effective dielectric function in FRET, which will be a unique, useful source for those who study and model FRET.

  1. Quantification of Global Left Ventricular Function: Comparison of Multidetector Computed Tomography and Magnetic Resonance Imaging. A Meta-analysis and Review of the Current Literature

    Energy Technology Data Exchange (ETDEWEB)

    Vleuten, P.A. van der; Willems, T.P.; Goette, M.J.; Tio, R.A.; Greuter, M.J.; Zijlstra, F.; Oudkerk, M. [Univ. Medical Centre Groningen (Netherlands). Depts. of Cardiology and Radiology

    2006-12-15

    Cardiac morbidity and mortality are closely related to cardiac volumes and global left ventricular (LV) function, expressed as left ventricular ejection fraction. Accurate assessment of these parameters is required for the prediction of prognosis in individual patients as well as in entire cohorts. The current standard of reference for left ventricular function is analysis by short-axis magnetic resonance imaging. In recent years, major extensive technological improvements have been achieved in computed tomography. The most marked development has been the introduction of the multidetector CT (MDCT), which has significantly improved temporal and spatial resolutions. In order to assess the current status of MDCT for analysis of LV function, the current available literature on this subject was reviewed. The data presented in this review indicate that the global left ventricular functional parameters measured by contemporary multi-detector row systems combined with adequate reconstruction algorithms and post-processing tools show a narrow diagnostic window and are interchangeable with those obtained by MRI.

  2. A Cell-to-Cell Battery Equalizer With Zero-Current Switching and Zero-Voltage Gap Based on Quasi-Resonant LC Converter and Boost Converter

    DEFF Research Database (Denmark)

    Shang, Yunlong; Zhang, Chenghui; Cui, Naxin

    2015-01-01

    voltage gap for large balancing current and ZVG between cells. Instead of a dedicated equalizer for each cell, only one balancing converter is employed and shared by all cells, reducing the size and implementation cost. Moreover, the equalization current can be regulated as needed by controlling the duty...... cycle of the BDDC, which not only prevents efficiently over-equalization but also abridges the balancing time. Simulation and experimental results show the proposed scheme exhibits outstanding balancing performance, and the energy conversion efficiency is higher than 98%. The validity of the proposed...... these difficulties, an innovative direct cell-to-cell battery equalizer based on quasi-resonant LC converter (QRLCC) and boost DC-DC converter (BDDC) is proposed. The QRLCC is employed to gain zero-current switching (ZCS), leading to a reduction of power losses. The BDDC is employed to enhance the equalization...

  3. The NaI D resonance lines in main-sequence late-type stars

    Science.gov (United States)

    Díaz, Rodrigo F.; Cincunegui, Carolina; Mauas, Pablo J. D.

    2007-07-01

    We study the sodium D lines (D1: 5895.92Å D2: 5889.95Å) in late-type dwarf stars. The stars have spectral types between F6 and M5.5 (B - V between 0.457 and 1.807) and metallicity between [Fe/H] = -0.82 and 0.6. We obtained medium-resolution echelle spectra using the 2.15-m telescope at the Argentinian observatory Complejo Astronómico El Leoncito (CASLEO). The observations have been performed periodically since 1999. The spectra were calibrated in wavelength and in flux. A definition of the pseudo-continuum level is found for all our observations. We also define a continuum level for calibration purposes. The equivalent width of the D lines is computed in detail for all our spectra and related to the colour index (B - V) of the stars. When possible, we perform a careful comparison with previous studies. Finally, we construct a spectral index (R'D) as the ratio between the flux in the D lines and the bolometric flux. We find that, once corrected for the photospheric contribution, this index can be used as a chromospheric activity indicator in stars with a high level of activity. Additionally, we find that combining some of our results, we obtain a method to calibrate in flux stars of unknown colour.

  4. The Na I D resonance lines in main sequence late-type stars

    CERN Document Server

    Díaz, Rodrigo F; Mauas, Pablo J D

    2007-01-01

    We study the sodium D lines (D1: 5895.92 \\AA; D2: 5889.95 \\AA) in late-type dwarf stars. The stars have spectral types between F6 and M5.5 (B-V between 0.457 and 1.807) and metallicity between [Fe/H] = -0.82 and 0.6. We obtained medium resolution echelle spectra using the 2.15-m telescope at the argentinian observatory CASLEO. The observations have been performed periodically since 1999. The spectra were calibrated in wavelength and in flux. A definition of the pseudo-continuum level is found for all our observations. We also define a continuum level for calibration purposes. The equivalent width of the D lines is computed in detail for all our spectra and related to the colour index (B-V) of the stars. When possible, we perform a careful comparison with previous studies. Finally, we construct a spectral index (R_D') as the ratio between the flux in the D lines, and the bolometric flux. We find that, once corrected for the photospheric contribution, this index can be used as a chromospheric activity indicator...

  5. Nonlinear resonances

    CERN Document Server

    Rajasekar, Shanmuganathan

    2016-01-01

    This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...

  6. Types and severity of medication errors in Iran; a review of the current literature.

    Science.gov (United States)

    Mansouri, Ava; Ahmadvand, Alireza; Hadjibabaie, Molouk; Kargar, Mona; Javadi, Mohammadreza; Gholami, Kheirollah

    2013-06-20

    Medication error (ME) is the most common single preventable cause of adverse drug events which negatively affects patient safety. ME prevalence is a valuable safety indicator in healthcare system. Inadequate studies on ME, shortage of high-quality studies and wide variations in estimations from developing countries including Iran, decreases the reliability of ME evaluations. In order to clarify the status of MEs, we aimed to review current available literature on this subject from Iran. We searched Scopus, Web of Science, PubMed, CINAHL, EBSCOHOST and also Persian databases (IranMedex, and SID) up to October 2012 to find studies on adults and children about prescription, transcription, dispensing, and administration errors. Two authors independently selected and one of them reviewed and extracted data for types, definitions and severity of MEs. The results were classified based on different stages of drug delivery process. Eighteen articles (11 Persian and 7 English) were included in our review. All study designs were cross-sectional and conducted in hospital settings. Nursing staff and students were the most frequent populations under observation (12 studies; 66.7%). Most of studies did not report the overall frequency of MEs aside from ME types. Most of studies (15; 83.3%) reported prevalence of administration errors between 14.3%-70.0%. Prescribing error prevalence ranged from 29.8%-47.8%. The prevalence of dispensing and transcribing errors were from 11.3%-33.6% and 10.0%-51.8% respectively. We did not find any follow up or repeated studies. Only three studies reported findings on severity of MEs. The most reported types of and the highest percentages for any type of ME in Iran were administration errors. Studying ME in Iran is a new area considering the duration and number of publications. Wide ranges of estimations for MEs in different stages may be because of the poor quality of studies with diversity in definitions, methods, and populations. For gaining

  7. Types and Severity of Medication Errors in Iran; a Review of the Current Literature

    Directory of Open Access Journals (Sweden)

    Ava Mansouri

    2013-06-01

    Full Text Available Medication error (ME is the most common single preventable cause of adverse drug events which negatively affects patient safety. ME prevalence is a valuable safety indicator in healthcare system. Inadequate studies on ME, shortage of high-quality studies and wide variations in estimations from developing countries including Iran, decreases the reliability of ME evaluations. In order to clarify the status of MEs, we aimed to review current available literature on this subject from Iran. We searched Scopus, Web of Science, PubMed, CINAHL, EBSCOHOST and also Persian databases (IranMedex, and SID up to October 2012 to find studies on adults and children about prescription, transcription, dispensing, and administration errors. Two authors independently selected and one of them reviewed and extracted data for types, definitions and severity of MEs. The results were classified based on different stages of drug delivery process. Eighteen articles (11 Persian and 7 English were included in our review. All study designs were cross-sectional and conducted in hospital settings. Nursing staff and students were the most frequent populations under observation (12 studies; 66.7%. Most of studies did not report the overall frequency of MEs aside from ME types. Most of studies (15; 83.3% reported prevalence of administration errors between 14.3%-70.0%. Prescribing error prevalence ranged from 29.8%-47.8%. The prevalence of dispensing and transcribing errors were from 11.3%-33.6% and 10.0%-51.8% respectively. We did not find any follow up or repeated studies. Only three studies reported findings on severity of MEs. The most reported types of and the highest percentages for any type of ME in Iran were administration errors. Studying ME in Iran is a new area considering the duration and number of publications. Wide ranges of estimations for MEs in different stages may be because of the poor quality of studies with diversity in definitions, methods, and populations

  8. Profile of L-type Ca2+ current and Na+/Ca2+ exchange current during cardiac action potential in ventricular myocytes

    Science.gov (United States)

    Banyasz, Tamas; Horvath, Balazs; Jian, Zhong; Izu, Leighton T.; Chen-Izu, Ye

    2011-01-01

    Objective The L-type Ca2+ current (ICa,L) and the Na+/Ca2+ exchange current (INCX) are major inward currents that shape the cardiac action potential (AP). Previously, the profile of these currents during AP was determined from voltage-clamp experiments that used Ca2+ buffer. In this study, we aimed to obtain direct experimental measurement of these currents during cardiac AP with Ca2+ cycling. Method A newly developed AP-clamp sequential dissection method was used to record ionic currents in guinea pig ventricular myocytes under a triad of conditions: using the cell’s own AP as the voltage command, using internal and external solutions that mimic the cell’s ionic composition and, importantly, no exogenous Ca2+ buffer was used. Results The nifedipine-sensitive current (INIFE), which is composed of ICa,L and INCX, revealed hitherto unreported features during AP with Ca2+ cycling in the cell. We identified two peaks in the current profile followed by a long residual current extending beyond the AP, coinciding with a residual depolarization. The second peak and the residual current become apparent only when Ca2+ is not buffered. Pharmacological dissection of INIFE using SEA0400 shows that ICa,L is dominant during phase-1&2 whereas INCX contributes significantly to the inward current at phase-3&4 of AP. Conclusion These data provide the first direct experimental visualization of ICa,L and INCX during cardiac AP and Ca2+ cycle. The residual current reported here can serve as a potential substrate for afterdepolarizations when increased under pathologic conditions. PMID:21884673

  9. Time-domain measurement of terahertz frequency magnetoplasmon resonances in a two-dimensional electron system by the direct injection of picosecond pulsed currents

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jingbo; Mayorov, Alexander S.; Wood, Christopher D.; Mistry, Divyang; Li, Lianhe; Linfield, Edmund H.; Giles Davies, A.; Cunningham, John E., E-mail: j.e.cunningham@leeds.ac.uk [School of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); Sydoruk, Oleksiy [Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)

    2016-02-29

    We have investigated terahertz (THz) frequency magnetoplasmon resonances in a two-dimensional electron system through the direct injection of picosecond duration current pulses. The evolution of the time-domain signals was measured as a function of magnetic field, and the results were found to be in agreement with calculations using a mode-matching approach for four modes observed in the frequency range above 0.1 THz. This introduces a generic technique suitable for sampling ultrafast carrier dynamics in low-dimensional semiconductor nanostructures at THz frequencies.

  10. Real-time measurements of the redox states of c-type cytochromes in electroactive biofilms: a confocal resonance Raman Microscopy study.

    Science.gov (United States)

    Virdis, Bernardino; Millo, Diego; Donose, Bogdan C; Batstone, Damien J

    2014-01-01

    Confocal Resonance Raman Microscopy (CRRM) was used to probe variations of redox state of c-type cytochromes embedded in living mixed-culture electroactive biofilms exposed to different electrode polarizations, under potentiostatic and potentiodynamic conditions. In the absence of the metabolic substrate acetate, the redox state of cytochromes followed the application of reducing and oxidizing electrode potentials. Real-time monitoring of the redox state of cytochromes during cyclic voltammetry (CV) in a potential window where cytochromes reduction occurs, evidenced a measurable time delay between the oxidation of redox cofactors probed by CV at the electrode interface, and oxidation of distal cytochromes probed by CRRM. This delay was used to tentatively estimate the diffusivity of electrons through the biofilm. In the presence of acetate, the resonance Raman spectra of young (10 days, j = 208 ± 49 µA cm(-2)) and mature (57 days, j = 267 ± 73 µA cm(-2)) biofilms show that cytochromes remained oxidized homogeneously even at layers as far as 70 µm from the electrode, implying the existence of slow metabolic kinetics that do not result in the formation of a redox gradient inside the biofilm during anode respiration. However, old biofilms (80 days, j = 190 ± 37 µA cm(-2)) with thickness above 100 µm were characterized by reduced catalytic activity compared to the previous developing stages. The cytochromes in these biofilm were mainly in the reduced redox state, showing that only aged mixed-culture biofilms accumulate electrons during anode respiration. These results differ substantially from recent observations in pure Geobacter sulfurreducens electroactive biofilms, in which accumulation of reduced cytochromes is already observed in thinner biofilms, thus suggesting different bottlenecks in current production for mixed-culture and G. sulfurreducens biofilms.

  11. Real-time measurements of the redox states of c-type cytochromes in electroactive biofilms: a confocal resonance Raman Microscopy study.

    Directory of Open Access Journals (Sweden)

    Bernardino Virdis

    Full Text Available Confocal Resonance Raman Microscopy (CRRM was used to probe variations of redox state of c-type cytochromes embedded in living mixed-culture electroactive biofilms exposed to different electrode polarizations, under potentiostatic and potentiodynamic conditions. In the absence of the metabolic substrate acetate, the redox state of cytochromes followed the application of reducing and oxidizing electrode potentials. Real-time monitoring of the redox state of cytochromes during cyclic voltammetry (CV in a potential window where cytochromes reduction occurs, evidenced a measurable time delay between the oxidation of redox cofactors probed by CV at the electrode interface, and oxidation of distal cytochromes probed by CRRM. This delay was used to tentatively estimate the diffusivity of electrons through the biofilm. In the presence of acetate, the resonance Raman spectra of young (10 days, j = 208 ± 49 µA cm(-2 and mature (57 days, j = 267 ± 73 µA cm(-2 biofilms show that cytochromes remained oxidized homogeneously even at layers as far as 70 µm from the electrode, implying the existence of slow metabolic kinetics that do not result in the formation of a redox gradient inside the biofilm during anode respiration. However, old biofilms (80 days, j = 190 ± 37 µA cm(-2 with thickness above 100 µm were characterized by reduced catalytic activity compared to the previous developing stages. The cytochromes in these biofilm were mainly in the reduced redox state, showing that only aged mixed-culture biofilms accumulate electrons during anode respiration. These results differ substantially from recent observations in pure Geobacter sulfurreducens electroactive biofilms, in which accumulation of reduced cytochromes is already observed in thinner biofilms, thus suggesting different bottlenecks in current production for mixed-culture and G. sulfurreducens biofilms.

  12. Magnetic resonance imaging arthrography following type II superior labrum from anterior to posterior repair: interobserver and intraobserver reliability

    Directory of Open Access Journals (Sweden)

    Kurji HM

    2015-11-01

    Full Text Available Hafeez M Kurji,1 Yohei Ono,2,3 Atiba A Nelson,2 Kristie D More,2 Ben Wong,4 Corinne Dyke,4 Richard S Boorman,2 Gail M Thornton,2,5 Ian KY Lo2 1College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada; 2Department of Surgery, Section of Orthopaedic Surgery, McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada; 3Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan; 4Department of Radiology, University of Calgary, Calgary, AB, Canada; 5Department of Orthopaedics, University of British Columbia, Vancouver, BC, Canada Background: Arthroscopic repair of type II superior labrum from anterior to posterior (SLAP lesions is a common surgical procedure. However, anatomic healing following repair has rarely been investigated. The intraobserver and interobserver reliability of magnetic resonance imaging arthrography (MRA following type II SLAP repair has not previously been investigated. This is of particular interest due to recent reports of poor clinical results following type II SLAP lesion repair. Purpose: To evaluate the MRA findings following arthroscopic type II SLAP lesion repair and determine its intraobserver and interobserver reliability. Study design: Cohort study (diagnosis, Level of Evidence, 2. Methods: Twenty-five patients with an isolated type II SLAP lesion (confirmed via diagnostic arthroscopy underwent standard suture anchor-based repair. At a mean of 25.2 months postoperatively, patients underwent a standardized MRA protocol to investigate the integrity of the repair. MRAs were independently reviewed by two radiologists and a fellowship trained shoulder surgeon. The outcomes were classified as healed SLAP repair or re-torn SLAP repair. Results: On average, 54% of MRAs were interpreted as healed SLAP repairs while 46% of MRAs were interpreted as having a re-torn SLAP repair. Overall, only 43% of the studies had 100% agreement across all

  13. Cardiac effects of 3 months treatment of acromegaly evaluated by magnetic resonance imaging and B-type natriuretic peptides

    DEFF Research Database (Denmark)

    Andreassen, Mikkel; Faber, Jens; Kjær, Andreas

    2010-01-01

    Long-term treatment of acromegaly prevents aggravation and reverses associated heart disease. A previous study has shown a temporary increase in serum levels of the N-terminal fraction of pro B-type natriuretic peptide (NT-proBNP) suggesting an initial decline in cardiac function when treatment...... of acromegaly is initiated. This was a three months prospective study investigating short-term cardiac effects of treatment in acromegalic patients. Cardiac function was evaluated by the gold standard method cardiac magnetic resonance imaging (CMRI) and circulating levels of B-type natriuretic peptides (BNP......) (95% CI 3-14), P = 0.007) and an increase in levels of BNP (median (ranges) 7 (0.58-286) vs. 20 (1-489) pg/mL, P = 0.033) and of NT-proBNP (63 (20-1004) vs. 80 (20-3391) pg/mL, P = 0.027). Assessed by the highly sensitive and precise CMRI method, 3 months treatment of acromegaly resulted...

  14. Glucocorticoids specifically enhance L-type calcium current amplitude and affect calcium channel subunit expression in the mouse hippocampus.

    Science.gov (United States)

    Chameau, Pascal; Qin, Yongjun; Spijker, Sabine; Smit, August Benjamin; Smit, Guus; Joëls, Marian

    2007-01-01

    Previous studies have shown that corticosterone enhances whole cell calcium currents in CA1 pyramidal neurons, through a pathway involving binding of glucocorticoid receptor homodimers to the DNA. We examined whether glucocorticoids show selectivity for L- over N-type of calcium currents. Moreover, we addressed the putative gene targets that eventually lead to the enhanced calcium currents. Electrophysiological recordings were performed in nucleated patches that allow excellent voltage control. Calcium currents in these patches almost exclusively involve N- and L-type channels. We found that L- but not N-type calcium currents were largely enhanced after treatment with a high dose of corticosterone sufficient to activate glucocorticoid receptors. Voltage dependency and kinetic properties of the currents were unaffected by the hormone. Nonstationary noise analysis suggests that the increased current is not caused by a larger unitary conductance, but rather to a doubling of the number of functional channels. Quantitative real-time PCR revealed that transcripts of the Ca(v)1 subunits encoding for the N- or L-type calcium channels are not upregulated in the mouse CA1 area; instead, a strong, direct, and consistent upregulation of the beta4 subunit was observed. This indicates that the corticosteroid-induced increase in number of L-type calcium channels is not caused by a simple transcriptional regulation of the pore-forming subunit of the channels.

  15. Glucocorticoids specifically enhance L-type calcium current amplitude and affect calcium channel subunit expression in the mouse hippocampus.

    NARCIS (Netherlands)

    Chameau, P.J.P.; Qin, Y.J.; Smit, G.; Joëls, M.

    2007-01-01

    Previous studies have shown that corticosterone enhances whole cell calcium currents in CA1 pyramidal neurons, through a pathway involving binding of glucocorticoid receptor homodimers to the DNA. We examined whether glucocorticoids show selectivity for L- over N-type of calcium currents. Moreover,

  16. Pharmacology and therapeutic implications of current drugs for type 2 diabetes mellitus.

    Science.gov (United States)

    Tahrani, Abd A; Barnett, Anthony H; Bailey, Clifford J

    2016-10-01

    Type 2 diabetes mellitus (T2DM) is a global epidemic that poses a major challenge to health-care systems. Improving metabolic control to approach normal glycaemia (where practical) greatly benefits long-term prognoses and justifies early, effective, sustained and safety-conscious intervention. Improvements in the understanding of the complex pathogenesis of T2DM have underpinned the development of glucose-lowering therapies with complementary mechanisms of action, which have expanded treatment options and facilitated individualized management strategies. Over the past decade, several new classes of glucose-lowering agents have been licensed, including glucagon-like peptide 1 receptor (GLP-1R) agonists, dipeptidyl peptidase 4 (DPP-4) inhibitors and sodium/glucose cotransporter 2 (SGLT2) inhibitors. These agents can be used individually or in combination with well-established treatments such as biguanides, sulfonylureas and thiazolidinediones. Although novel agents have potential advantages including low risk of hypoglycaemia and help with weight control, long-term safety has yet to be established. In this Review, we assess the pharmacokinetics, pharmacodynamics and safety profiles, including cardiovascular safety, of currently available therapies for management of hyperglycaemia in patients with T2DM within the context of disease pathogenesis and natural history. In addition, we briefly describe treatment algorithms for patients with T2DM and lessons from present therapies to inform the development of future therapies.

  17. Morphological and optical properties of n-type porous silicon: effect of etching current density

    Indian Academy of Sciences (India)

    M DAS; D SARKAR

    2016-12-01

    Morphological and optical properties of porous silicon (PS) layer fabricated on n-type silicon wafer have been reported in the present article. Method of PS fabrication is by photo-assisted electrochemical etching with different etching current densities ($J$). Porosity and PS layer thickness, obtained by the gravimetric method, increase with increasing $J$. Pore morphology observed by FESEM shows the presence of randomly distributed pores with mostly spherical shape. Calculated pore size is also seen to increase with increasing value of $J$. XRD gives the characteristic amorphous peak of PS along with some peaks corresponding to crystalline silicon (c-Si). Calculated crystallite size shows decreasing trend with increasing $J$ value. The optical properties of these samples have been investigated by UV–visible reflectance, Raman spectroscopy and photoluminescence (PL) spectra. Reflectance measurement shows blue-shift of the spectrum with increased reflectivity for increasing $J$. Raman spectra show remarkable blue-shift with respect to the c-Si peak. PL spectra give the luminescence energy in the orange–red region of the visible spectrum and little change with variation of $J$.

  18. Design of shielded encircling send-receive type pulsed eddy current probe using numerical analysis method

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Young Kil [Dept. of Electircal Engineeirng, Kunsan National University, Kunsan (Korea, Republic of)

    2013-12-15

    An encircling send-receive type pulsed eddy current (PEC) probe is designed for use in aluminum tube inspection. When bare receive coils located away from the exciter were used, the peak time of the signal did not change although the distance from the exciter increased. This is because the magnetic flux from the exciter coil directly affects the receive coil signal. Therefore, in this work, both the exciter and the sensor coils were shielded in order to reduce the influence of direct flux from the exciter coil. Numerical simulation with the designed shielded encircling PEC probe showed the corresponding increase of the peak time as the sensor distance increased. Ferrite and carbon steel shields were compared and results of the ferrite shielding showed a slightly stronger peak value and a quicker peak time than those of the carbon steel shielding. Simulation results showed that the peak value increased as the defect size (such as depth and length) increased regardless of the sensor location. To decide a proper sensor location, the sensitivity of the peak value to defect size variation was investigated and found that the normalized peak value was more sensitive to defect size variation when the sensor was located closer to the exciter.

  19. CARDIOVASCULAR DISEASES TREATMENT IN PATIENTS WITH TYPE 2 DIABETES MELLITUS IN CURRENT CLINICAL PRACTICE

    Directory of Open Access Journals (Sweden)

    I. E. Sapozhnikova

    2016-01-01

    Full Text Available Aim. To evaluate cardiovascular diseases (CVD treatment in patients with type 2 diabetes mellitus (DM 2 in current clinical practice.Material and methods. A total of 200 patients with DM 2, who consented to take part in the questionnaire, were examined. Questionnaire, clinical and laboratory examinations were conducted.Results. There was a low frequency of CVD recognized and included into clinical diagnosis – angina, history of myocardial infarction and stroke. In majority of the patients decompensated carbohydrate metabolism was observed. This was due to lack of knowledge, inadequate or absent glucose self-monitoring, low frequency of combined glucoselowering therapy. Target level of blood pressure (BP was registered in 16% of hypertensive patients only. Basic reasons of this were: frequently prescribed mono-therapy, irrational combinations, inadequate dosage and frequent omissions of antihypertensive drugs intake and not appropriate BP self-monitoring. Low frequency of statins therapy and non-targeted cholesterol levels were also revealed in examined patients.Conclusion. Improvement of diagnostic tactics in patients with DM 2 is necessary as well as therapy correction taking into account these patients co-morbidity.

  20. CARDIOVASCULAR DISEASES TREATMENT IN PATIENTS WITH TYPE 2 DIABETES MELLITUS IN CURRENT CLINICAL PRACTICE

    Directory of Open Access Journals (Sweden)

    I. E. Sapozhnikova

    2009-01-01

    Full Text Available Aim. To evaluate cardiovascular diseases (CVD treatment in patients with type 2 diabetes mellitus (DM 2 in current clinical practice.Material and methods. A total of 200 patients with DM 2, who consented to take part in the questionnaire, were examined. Questionnaire, clinical and laboratory examinations were conducted.Results. There was a low frequency of CVD recognized and included into clinical diagnosis – angina, history of myocardial infarction and stroke. In majority of the patients decompensated carbohydrate metabolism was observed. This was due to lack of knowledge, inadequate or absent glucose self-monitoring, low frequency of combined glucoselowering therapy. Target level of blood pressure (BP was registered in 16% of hypertensive patients only. Basic reasons of this were: frequently prescribed mono-therapy, irrational combinations, inadequate dosage and frequent omissions of antihypertensive drugs intake and not appropriate BP self-monitoring. Low frequency of statins therapy and non-targeted cholesterol levels were also revealed in examined patients.Conclusion. Improvement of diagnostic tactics in patients with DM 2 is necessary as well as therapy correction taking into account these patients co-morbidity.

  1. Barnidipine block of L-type Ca(2+) channel currents in rat ventricular cardiomyocytes.

    Science.gov (United States)

    Wegener, J W; Meyrer, H; Rupp, J; Nawrath, H

    2000-08-01

    The effects of barnidipine and nifedipine on L-type Ca(2+) current (I(Ca(L))) were investigated in ventricular cardiomyocytes from rats. Both barnidipine and nifedipine reduced I(Ca(L)) in a concentration and voltage dependent manner; the EC(50) were 80 and 130 nM at a holding potential of -80 mV, respectively, and 18 and 6 nM at -40 mV, respectively. Both drugs induced a leftward shift of the steady-state inactivation curve of I(Ca(L)). Using a twin pulse protocol, the relationships between the amount of block of I(Ca(L)) by either drug, seen during the second pulse, and the length of the first pulse were described by monoexponential functions reflecting onset of block, dependent on drug concentration. The onset of block by barnidipine was three times faster than that by nifedipine. With both drugs, recovery of I(Ca(L)) was 50 times slower than under control conditions and described by monoexponential functions reflecting offset of block (independent of drug concentration). The offset of block with barnidipine was three times slower than that with nifedipine. The time constants of block and unblock of I(Ca(L)) by both drugs were used to calculate binding and unbinding and to predict their effects at two frequencies. It is suggested that barnidipine exhibits a higher affinity to the inactivated Ca(2+) channel state as compared to nifedipine.

  2. Barnidipine block of L-type Ca2+ channel currents in rat ventricular cardiomyocytes

    Science.gov (United States)

    Wegener, Jörg W; Meyrer, Hans; Rupp, Johanna; Nawrath, Hermann

    2000-01-01

    The effects of barnidipine and nifedipine on L-type Ca2+ current (ICa(L)) were investigated in ventricular cardiomyocytes from rats.Both barnidipine and nifedipine reduced ICa(L) in a concentration and voltage dependent manner; the EC50 were 80 and 130 nM at a holding potential of −80 mV, respectively, and 18 and 6 nM at −40 mV, respectively.Both drugs induced a leftward shift of the steady-state inactivation curve of ICa(L).Using a twin pulse protocol, the relationships between the amount of block of ICa(L) by either drug, seen during the second pulse, and the length of the first pulse were described by monoexponential functions reflecting onset of block, dependent on drug concentration. The onset of block by barnidipine was three times faster than that by nifedipine.With both drugs, recovery of ICa(L) was 50 times slower than under control conditions and described by monoexponential functions reflecting offset of block (independent of drug concentration). The offset of block with barnidipine was three times slower than that with nifedipine.The time constants of block and unblock of ICa(L) by both drugs were used to calculate binding and unbinding and to predict their effects at two frequencies.It is suggested that barnidipine exhibits a higher affinity to the inactivated Ca2+ channel state as compared to nifedipine. PMID:10952695

  3. Design of encircling send-receive type pulsed eddy current probe

    Science.gov (United States)

    Shin, Young-Kil

    2014-02-01

    An encircling send-receive type pulsed eddy current (PEC) probe is designed for use in the tube inspection. When bare receive coils, which are located away from the exciter, are used, the peak time of the signal does not change although the distance from the exciter increases. This is because the magnetic fields from exciter coil arrive directly at the receive coil without passing through the tube. Therefore, in this work, both exciter and sensor coils are shielded to reduce the influence of direct fields from the exciter coil. Numerical simulation with the designed shielded encircling PEC probe shows the corresponding increase of peak time as the sensor distance increases. Ferrite and carbon steel shields are compared and found that the ferrite shielding results in slightly stronger peak value and quicker peak time than the carbon steel shielding. Sensitivity of peak value to defect depth variation is also investigated and found that the normalized peak value is more sensitive when the sensor is located closer to the exciter for aluminum tube. In the case of magnetic tube, however, all the characteristics are opposite to those obtained from nonmagnetic aluminum tube.

  4. The current unmet need in type 2 diabetes mellitus: addressing glycemia and cardiovascular disease.

    Science.gov (United States)

    Levy, Philip

    2009-05-01

    The treatment of type 2 diabetes mellitus (T2DM) requires a multifaceted approach of both lifestyle modification (diet, exercise, weight control, smoking cessation) and pharmacological therapy. In addition to agents that improve hyperglycemia, patients often require treatments to address the additional cardiovascular (CV) risk factors of hypertension and dyslipidemia. Although the benefits of early, aggressive glycemic control are clearly established, treatment remains suboptimal. Many patients fail to achieve long-term glycemic control, with rates of patients with T2DM achieving target goals for hypertension and dyslipidemia also unsatisfactory. Several factors contribute to the failure to meet treatment goals. These include poor adherence by patients to lifestyle and pharmacological treatment, lack of understanding by patients of the long-term benefits of treatment, patient concerns about adverse effects leading to poor compliance, and failure of health care providers to initiate or intensify medications appropriately (termed clinical inertia). This article reviews the current state of T2DM treatment and the management of CV risk factors associated with T2DM, and identifies unmet treatment needs.

  5. Nanoelectronic devices--resonant tunnelling diodes grown on InP substrates by molecular beam epitaxy with peak to valley current ratio of 17 at room temperature

    Institute of Scientific and Technical Information of China (English)

    Zhang Yang; Zeng Yi-Ping; Ma Long; Wang Bao-Qiang; Zhu Zhan-Ping; Wang Liang-Chen; Yang Fu-Hua

    2006-01-01

    This paper reports that InAs/In0.53Ga0.47As/AlAs resonant tunnelling diodes have been grown on InP substrates by molecular beam epitaxy. Peak to valley current ratio of these devices is 17 at 300K. A peak current density of 3kA/cm2 has been obtained for diodes with AlAs barriers of ten monolayers, and an In0.53Ga0.47As well of eight monolayers with four monolayers of InAs insert layer. The effects of growth interruption for smoothing potential barrier interfaces have been investigated by high resolution transmission electron microscope.

  6. Resistance switching memory operation using the bistability in current-voltage characteristics of GaN/AlN resonant tunneling diodes

    Science.gov (United States)

    Nagase, Masanori; Takahashi, Tokio; Shimizu, Mitsuaki

    2016-10-01

    Resistance switching memory operations using the bistability in the current-voltage (I-V) characteristics of GaN/AlN resonant tunneling diodes (RTDs) were investigated to realize an ultrafast nonvolatile memory operating at a picosecond time scale. Resistance switching memory operations based on electron accumulation due to intersubband transitions and electron release due to tunneling current were demonstrated with high reproducibility at room temperature when the leakage of electrons accumulating in the quantum well from the deep level in the AlN barrier was suppressed. A nonvolatile memory for the processor core in a normally off computing system is expected to be realized using the bistability in the I-V characteristics of GaN/AlN RTDs.

  7. Discrimination between spin-dependent charge transport and spin-dependent recombination in π-conjugated polymers by correlated current and electroluminescence-detected magnetic resonance

    Science.gov (United States)

    Kavand, Marzieh; Baird, Douglas; van Schooten, Kipp; Malissa, Hans; Lupton, John M.; Boehme, Christoph

    2016-08-01

    Spin-dependent processes play a crucial role in organic electronic devices. Spin coherence can give rise to spin mixing due to a number of processes such as hyperfine coupling, and leads to a range of magnetic field effects. However, it is not straightforward to differentiate between pure single-carrier spin-dependent transport processes which control the current and therefore the electroluminescence, and spin-dependent electron-hole recombination which determines the electroluminescence yield and in turn modulates the current. We therefore investigate the correlation between the dynamics of spin-dependent electric current and spin-dependent electroluminescence in two derivatives of the conjugated polymer poly(phenylene-vinylene) using simultaneously measured pulsed electrically detected (pEDMR) and optically detected (pODMR) magnetic resonance spectroscopy. This experimental approach requires careful analysis of the transient response functions under optical and electrical detection. At room temperature and under bipolar charge-carrier injection conditions, a correlation of the pEDMR and the pODMR signals is observed, consistent with the hypothesis that the recombination currents involve spin-dependent electronic transitions. This observation is inconsistent with the hypothesis that these signals are caused by spin-dependent charge-carrier transport. These results therefore provide no evidence that supports earlier claims that spin-dependent transport plays a role for room-temperature magnetoresistance effects. At low temperatures, however, the correlation between pEDMR and pODMR is weakened, demonstrating that more than one spin-dependent process influences the optoelectronic materials' properties. This conclusion is consistent with prior studies of half-field resonances that were attributed to spin-dependent triplet exciton recombination, which becomes significant at low temperatures when the triplet lifetime increases.

  8. Effects of Angiotensin Ⅱ and ACE Inhibitor, Captopril on L-type Calcium Current and Sodium Current of Single Guinea Myocytes

    Institute of Scientific and Technical Information of China (English)

    徐延敏; 黄体钢; 陈元禄

    2002-01-01

    Objectives To investigateeffect of AngⅡ, captopril on single guinea myocytes onL - type calcium current and sodium current. MethodsMembrane patch clamp whole cell recording tech-nique was used to investigate effect of angⅡ, captoprilon L- Ca maximum current density and sodium maxi-mum current density. Resutls AngⅡ increased themaximum current density compared with control afterpeffused 5 min, 357.7±219.7 Vs 279.5±240.5PA/PF, increase rate is 27.9 %, the shape of current- voltage relationship curve was unchanged, peaked at+ 10 my, indicated that angⅡ increased L- Ca cur-rent density in voltage -dependent. After perfusedwith captopril, captopril ± angⅡ 3, 5 rmin, L-Cacurrent was recorded, results suggest L - Ca maximumcurrent density decreased significantly compared withcontrol, in captopril group, 128.4 ± 92.6Vs286.2 ±89.7, 66.7 ±68.3Vs 286.2 ± 89.7, respectively, rateof inhibition is 55.1%, 76.6 %, respectively. L - Cacurrent further decreased in captopril perfused 5 mincompared with 3 rmin, 66.7 ± 68.3 Vs 128.4 ± 92.6,in captopril + angⅡ group, L- Ca current decreasedgreatly in 3, 5 min than control, 143.4 ± 117.6Vs267.7±141.4, 96.4±82.5 Vs 267.7+141.4, re-spectively, rate of inhibition is 46.4 %, 63.9 % re-spectively. We also investigated effect of captopril onNa current, which decreased significantly in 1 rmin and3 rmin compared with control, 939.1 ±319. 1 Vs1398.0 ± 144.6 PA/PF, 469.95±314.9 Vs 1398.0±144.6 PA/PF, respectively, rate of inhibition is32.8 %, 66. 3 %, respectively. Na current density de-creased significantly in 3 min compared with 1 min,469.9 ± 314.9 Vs 939. 1 ± 319. 1PA/PF, rate of in-hibition is 49.9 % . Conclusions Angiotensin Ⅱexerts increased maximum current density of L - Ca involtage dependent, captopril decreased maximum cur-rent density of L - Ca in voltage dependent, decreasedsodium maximum current density, which is the promi-nently antiarrhythmia mechanisms through inhibition ofangiotensin Ⅱ evoked

  9. Theory and Applications of Surface Plasmon Resonance, Resonant Mirror, Resonant Waveguide Grating, and Dual Polarization Interferometry Biosensors

    Directory of Open Access Journals (Sweden)

    Billy W. Day

    2010-11-01

    Full Text Available Biosensors have been used extensively in the scientific community for several purposes, most notably to determine association and dissociation kinetics, protein-ligand, protein-protein, or nucleic acid hybridization interactions. A number of different types of biosensors are available in the field, each with real or perceived benefits over the others. This review discusses the basic theory and operational arrangements of four commercially available types of optical biosensors: surface plasmon resonance, resonant mirror, resonance waveguide grating, and dual polarization interferometry. The different applications these techniques offer are discussed from experiments and results reported in recently published literature. Additionally, recent advancements or modifications to the current techniques are also discussed.

  10. [Retinotopic mapping of the human visual cortex with functional magnetic resonance imaging - basic principles, current developments and ophthalmological perspectives].

    Science.gov (United States)

    Hoffmann, M B; Kaule, F; Grzeschik, R; Behrens-Baumann, W; Wolynski, B

    2011-07-01

    Since its initial introduction in the mid-1990 s, retinotopic mapping of the human visual cortex, based on functional magnetic resonance imaging (fMRI), has contributed greatly to our understanding of the human visual system. Multiple cortical visual field representations have been demonstrated and thus numerous visual areas identified. The organisation of specific areas has been detailed and the impact of pathophysiologies of the visual system on the cortical organisation uncovered. These results are based on investigations at a magnetic field strength of 3 Tesla or less. In a field-strength comparison between 3 and 7 Tesla, it was demonstrated that retinotopic mapping benefits from a magnetic field strength of 7 Tesla. Specifically, the visual areas can be mapped with high spatial resolution for a detailed analysis of the visual field maps. Applications of fMRI-based retinotopic mapping in ophthalmological research hold promise to further our understanding of plasticity in the human visual cortex. This is highlighted by pioneering studies in patients with macular dysfunction or misrouted optic nerves.

  11. The bridge-type fault current controller--a new facts controller

    Energy Technology Data Exchange (ETDEWEB)

    Boenig, Heinrich J.; Mielke, C. H. (Charles H.); Burley, B. L. (Burt L.); Chen, Hong; Waynert, J. A. (Joseph A.); Willis, J. O. (Jeffrey O.)

    2002-01-01

    The operation of a novel current controller, which can also function as a fault current limiter and as a solid-state ac circuit breaker, is presented. The controller, which consists of a thyristor bridge, an inductor, and an optional bias power supply, is installed in series with the voltage source and the load, For load current values smaller than a preset value, the inductor of the current controller presents no impedance to the ac current flow. For values higher than the preset current value, the inductor is switched automatically into the ac circuit and limits the amount of current flow. Theoretical results in the form of circuit simulations and experimental results with a single-phase unit, operating on a 13.7 kV three-phase system with peak short-circuit currents of 3140 Arms, are presented.

  12. Two dimensional simulation of direct methanol fuel cell : a new (embedded) type of current collectors

    OpenAIRE

    Kulikovsky, A. A.; Divisek, J.; Kornyshev, Yu. M.

    2000-01-01

    A two-dimensional numerical model of the direct methanol fuel cell with gas fuel is developed. Simulation of the cell with current collectors of conventional geometry reveal the formation of fuel-depleted, "shaded" regions in the cathode and anode catalyst layers. These regions are positioned in front of current collectors, farther from the gas channel windows. Another disadvantage of the conventional geometry is the concentration of electron current at the edges of current collectors. Based ...

  13. Type of tunable guided-mode resonance filter based on electro-optic characteristic of polymer-dispersed liquid crystal.

    Science.gov (United States)

    Wang, Qi; Zhang, Dawei; Huang, Yuanshen; Ni, Zhengji; Chen, Jiabi; Zhong, Yangwan; Zhuang, Songlin

    2010-04-15

    A narrowband guided-mode resonance filter (GMRF) incorporating polymer-dispersed liquid crystal (PDLC) is designed. Simulating the characteristics of the filter with rigorous coupled-wave analysis, we find that the resonance wavelength of the new kind of GMRF can be tuned from 672.4 to 698.4 nm by varying the refractive index of the PDLC layer with the applied voltage. Furthermore, the resonance wavelengths vary in a linear fashion with respect to the refractive index of the PDLC layer. Therefore, the desired resonance wavelength can be conveniently selected and tuned in a tuning range of 26 nm by using the applied voltage.

  14. Field-induced inversion of resonant tunneling currents through single molecule junctions and the directional photo-electric effect

    Science.gov (United States)

    Kuperman, Maayan; Peskin, Uri

    2017-03-01

    It has been known for several decades that the electric current through tunneling junctions is affected by irradiation. In particular, photon-assisted currents by asymmetric irradiation of the two leads was demonstrated and studied extensively in tunneling junctions of different compositions and for different radiation wavelengths. In this work, this phenomenon is revisited in the context of single molecule junctions. Restricting the theoretical discussion to adiabatic periodic driving of one lead with respect to the other within a non-interacting electron formulation, the main features of specific molecules are encoded in the discrete electronic energy levels. The detailed level structure of the molecule is shown to yield new effects in the presence of asymmetric driving of the leads. In particular, when the field-free tunneling process is dominated by a single electronic level, the electric current can be suppressed to zero or flow against the direction of an applied static bias. In the presence of a second electronic level, a directional photo-electric effect is predicted, where not only the magnitude but also the direction of the steady state electric current through the tunneling junction can be changed by a monotonous increase of the field intensity. These effects are analyzed and explained by outlying the relevant theory, using analytic expressions in the wide-band limit, as well as numerical simulations beyond this limit.

  15. Note: Modified π-type Butterworth-Van Dyke model for dual-mode Lamb-wave resonator with precise two-port Y-parameter characterizations

    Science.gov (United States)

    Wang, Yong; Hong, Yan; Goh, Wang Ling; Mu, Xiaojing

    2016-10-01

    Dual-mode Lamb-wave resonator has become a powerful component for clock reference and sensing applications, enabling efficient compensations of temperature effects, concurrent measurements of multiple environmental parameters, etc. An equivalent circuit model for the dual-mode Lamb-wave resonator is indispensable as it provides a means as well as being an effective tool for evaluating device characteristics and to aid the designing of circuitry for the resonators. This could be the first time ever that an efficient equivalent-circuit model, i.e., modified π-type Butterworth-Van Dyke model for dual-mode Lamb-wave resonators is reported. Evaluated by experiments, this model attains noteworthy agreements on both the magnitudes and phases of Y11 and Y21 of the measurement results. Compared to literature, the proposed model is capable of modeling the dual resonances efficiently. Moreover, this work also proves more accurate when viewing the Y-parameters across a wide frequency range. The gained features of this model are most beneficial for the analysis of the dual-mode Lamb-wave resonator and also for the designing of circuits.

  16. Note: Modified π-type Butterworth-Van Dyke model for dual-mode Lamb-wave resonator with precise two-port Y-parameter characterizations.

    Science.gov (United States)

    Wang, Yong; Hong, Yan; Goh, Wang Ling; Mu, Xiaojing

    2016-10-01

    Dual-mode Lamb-wave resonator has become a powerful component for clock reference and sensing applications, enabling efficient compensations of temperature effects, concurrent measurements of multiple environmental parameters, etc. An equivalent circuit model for the dual-mode Lamb-wave resonator is indispensable as it provides a means as well as being an effective tool for evaluating device characteristics and to aid the designing of circuitry for the resonators. This could be the first time ever that an efficient equivalent-circuit model, i.e., modified π-type Butterworth-Van Dyke model for dual-mode Lamb-wave resonators is reported. Evaluated by experiments, this model attains noteworthy agreements on both the magnitudes and phases of Y11 and Y21 of the measurement results. Compared to literature, the proposed model is capable of modeling the dual resonances efficiently. Moreover, this work also proves more accurate when viewing the Y-parameters across a wide frequency range. The gained features of this model are most beneficial for the analysis of the dual-mode Lamb-wave resonator and also for the designing of circuits.

  17. Extracting S-matrix poles for resonances from numerical scattering data: Type-II Padé reconstruction

    Science.gov (United States)

    Sokolovski, D.; Akhmatskaya, E.; Sen, S. K.

    2011-02-01

    We present a FORTRAN 77 code for evaluation of resonance pole positions and residues of a numerical scattering matrix element in the complex energy (CE) as well as in the complex angular momentum (CAM) planes. Analytical continuation of the S-matrix element is performed by constructing a type-II Padé approximant from given physical values (Bessis et al. (1994) [42]; Vrinceanu et al. (2000) [24]; Sokolovski and Msezane (2004) [23]). The algorithm involves iterative 'preconditioning' of the numerical data by extracting its rapidly oscillating potential phase component. The code has the capability of adding non-analytical noise to the numerical data in order to select 'true' physical poles, investigate their stability and evaluate the accuracy of the reconstruction. It has an option of employing multiple-precision (MPFUN) package (Bailey (1993) [45]) developed by D.H. Bailey wherever double precision calculations fail due to a large number of input partial waves (energies) involved. The code has been successfully tested on several models, as well as the F + H 2 → HF + H, F + HD → HF + D, Cl + HCl → ClH + Cl and H + D 2 → HD + D reactions. Some detailed examples are given in the text. Program summaryProgram title: PADE II Catalogue identifier: AEHO_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHO_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 19 959 No. of bytes in distributed program, including test data, etc.: 158 380 Distribution format: tar.gz Programming language: FORTRAN 77 Computer: Any computer equipped with a FORTRAN 90 compiler Operating system: UNIX, LINUX RAM: 256 Mb Classification: 16.8 External routines: NAG Program Library ( http://www.nag.co.uk/numeric/fl/FLdescription.asp) Nature of problem: The package extracts the positions and

  18. Hydrogen sulfide inhibits L-type calcium currents depending upon the protein sulfhydryl state in rat cardiomyocytes.

    Directory of Open Access Journals (Sweden)

    Rongyuan Zhang

    Full Text Available Hydrogen sulfide (H(2S is a novel gasotransmitter that inhibits L-type calcium currents (I (Ca, L. However, the underlying molecular mechanisms are unclear. In particular, the targeting site in the L-type calcium channel where H(2S functions remains unknown. The study was designed to investigate if the sulfhydryl group could be the possible targeting site in the L-type calcium channel in rat cardiomyocytes. Cardiac function was measured in isolated perfused rat hearts. The L-type calcium currents were recorded by using a whole cell voltage clamp technique on the isolated cardiomyocytes. The L-type calcium channel containing free sulfhydryl groups in H9C2 cells were measured by using Western blot. The results showed that sodium hydrosulfide (NaHS, an H(2S donor produced a negative inotropic effect on cardiac function, which could be partly inhibited by the oxidant sulfhydryl modifier diamide (DM. H(2S donor inhibited the peak amplitude of I( Ca, L in a concentration-dependent manner. However, dithiothreitol (DTT, a reducing sulfhydryl modifier markedly reversed the H(2S donor-induced inhibition of I (Ca, L in cardiomyocytes. In contrast, in the presence of DM, H(2S donor could not alter cardiac function and L type calcium currents. After the isolated rat heart or the cardiomyocytes were treated with DTT, NaHS could markedly alter cardiac function and L-type calcium currents in cardiomyocytes. Furthermore, NaHS could decrease the functional free sulfhydryl group in the L-type Ca(2+ channel, which could be reversed by thiol reductant, either DTT or reduced glutathione. Therefore, our results suggest that H(2S might inhibit L-type calcium currents depending on the sulfhydryl group in rat cardiomyocytes.

  19. Magnetic Resonance Imaging Plaque Hemorrhage for Risk Stratification in Carotid Artery Disease With Moderate Risk Under Current Medical Therapy.

    Science.gov (United States)

    Hosseini, Akram A; Simpson, Richard J; Altaf, Nishath; Bath, Philip M; MacSweeney, Shane T; Auer, Dorothee P

    2017-03-01

    Magnetic resonance imaging (MRI)-defined carotid plaque hemorrhage (MRIPH) can predict recurrent cerebrovascular ischemic events in severe symptomatic carotid stenosis. It is less clear whether MRIPH can improve risk stratification despite optimized medical secondary prevention in those with moderate risk. One-hundred fifty-one symptomatic patients with 30% to 99% carotid artery stenosis (median age: 77, 60.5% men) clinically deemed to not benefit from endarterectomy were prospectively recruited to undergo MRI and clinical follow-up (mean, 22 months). The clinical carotid artery risk score could be evaluated in 88 patients. MRIPH+ve was defined as plaque intensity >150% that of adjacent muscle. Survival analyses were performed with recurrent infarction (stroke or diffusion-positive cerebral ischemia) as the main end point. Fifty-five participants showed MRIPH+ve; 47 had low, 36 intermediate, and 5 high carotid artery risk scores. Cox regression showed MRIPH as a strong predictor of future infarction (hazard ratio, 5.2; 95% confidence interval, 1.64-16.34; P=0.005, corrected for degree of stenosis), also in the subgroup with 50% to 69% stenosis (hazard ratio, 4.1; 95% confidence interval, 1-16.8; P=0.049). The absolute risk of future infarction was 31.7% at 3 years in MRIPH+ve versus 1.8% in patients without (Pmedication with clinically uncertain benefit from recanalization, that is, those with moderate degree stenosis and intermediate carotid artery risk scores, MRIPH offers additional risk stratification. © 2017 American Heart Association, Inc.

  20. Mitigation of ion-induced drift instability in electron plasma by a transverse current through the Landau-resonant layer

    Science.gov (United States)

    Kabantsev, A. A.; Driscoll, C. F.

    2016-10-01

    Experiments and theory on electron columns have characterized an algebraic damping of diocotron modes, caused by a flux of electrons through the resonance (critical) layer. This flux-driven damping also eliminates the ion-induced exponential instability of diocotron modes. Our plasmas rotate at rate ωE × B, and the (nominally stable) diocotron modes are described by amplitude Ad ,kz = 0 ,mθ = 1 , 2 , . . , frequency ωd(mθ) , and a wave/plasma critical radius rc(mθ) , where ωE × B(rc) =ωd/mθ mθ. External fields produce a low density (1/100) halo of electrons moving radially outward from the plasma core, with flux rate F ≡(- 1/-1Ne) dNe/dt) dNe dt. We find that algebraicdamping of the diocotron modes begins when the halo reaches the critical radius rc(mθ) , proceeding as Ad(Δt) =Ad(0) - γΔt , with γ = β(mθ) F . We also investigated the diocotron instability which occurs when a small number of ions are transiting the electron plasma. Dissimilar bounce-averaged drifts of electrons and ions polarize the diocotron mode density perturbations, developing instability analogous to the classical flute instability. The exponential growth rate Γ is proportional to the fractional neutralization (Ni/Ne) and to the separation between electrons and ions in the wave perturbation. We have found that the algebraic damping can suppress the exponential ion-induced instability only for amplitudes satisfying Ad <= βF/Γ. Supported by NSF Grant PHY-1414570, DOE Grants DE-SC0002451.

  1. Mathematical Modeling of Subthreshold Resonant Properties in Pyloric Dilator Neurons

    Directory of Open Access Journals (Sweden)

    Babak Vazifehkhah Ghaffari

    2015-01-01

    Full Text Available Various types of neurons exhibit subthreshold resonance oscillation (preferred frequency response to fluctuating sinusoidal input currents. This phenomenon is well known to influence the synaptic plasticity and frequency of neural network oscillation. This study evaluates the resonant properties of pacemaker pyloric dilator (PD neurons in the central pattern generator network through mathematical modeling. From the pharmacological point of view, calcium currents cannot be blocked in PD neurons without removing the calcium-dependent potassium current. Thus, the effects of calcium ICa and calcium-dependent potassium IKCa currents on resonant properties remain unclear. By taking advantage of Hodgkin-Huxley-type model of neuron and its equivalent RLC circuit, we examine the effects of changing resting membrane potential and those ionic currents on the resonance. Results show that changing the resting membrane potential influences the amplitude and frequency of resonance so that the strength of resonance (Q-value increases by both depolarization and hyperpolarization of the resting membrane potential. Moreover, hyperpolarization-activated inward current Ih and ICa (in association with IKCa are dominant factors on resonant properties at hyperpolarized and depolarized potentials, respectively. Through mathematical analysis, results indicate that Ih and IKCa affect the resonant properties of PD neurons. However, ICa only has an amplifying effect on the resonance amplitude of these neurons.

  2. Mathematical modeling of subthreshold resonant properties in pyloric dilator neurons.

    Science.gov (United States)

    Vazifehkhah Ghaffari, Babak; Kouhnavard, Mojgan; Aihara, Takeshi; Kitajima, Tatsuo

    2015-01-01

    Various types of neurons exhibit subthreshold resonance oscillation (preferred frequency response) to fluctuating sinusoidal input currents. This phenomenon is well known to influence the synaptic plasticity and frequency of neural network oscillation. This study evaluates the resonant properties of pacemaker pyloric dilator (PD) neurons in the central pattern generator network through mathematical modeling. From the pharmacological point of view, calcium currents cannot be blocked in PD neurons without removing the calcium-dependent potassium current. Thus, the effects of calcium (I(Ca)) and calcium-dependent potassium (I(KCa)) currents on resonant properties remain unclear. By taking advantage of Hodgkin-Huxley-type model of neuron and its equivalent RLC circuit, we examine the effects of changing resting membrane potential and those ionic currents on the resonance. Results show that changing the resting membrane potential influences the amplitude and frequency of resonance so that the strength of resonance (Q-value) increases by both depolarization and hyperpolarization of the resting membrane potential. Moreover, hyperpolarization-activated inward current (I(h)) and I(Ca) (in association with I(KCa)) are dominant factors on resonant properties at hyperpolarized and depolarized potentials, respectively. Through mathematical analysis, results indicate that I h and I(KCa) affect the resonant properties of PD neurons. However, I(Ca) only has an amplifying effect on the resonance amplitude of these neurons.

  3. Nuclear magnetic resonance lipoprotein abnormalities in newly-diagnosed type 2 diabetes and their association with preclinical carotid atherosclerosis.

    Science.gov (United States)

    Amor, Antonio J; Catalan, Marta; Pérez, Antonio; Herreras, Zoe; Pinyol, Montserrat; Sala-Vila, Aleix; Cofán, Montserrat; Gilabert, Rosa; Ros, Emilio; Ortega, Emilio

    2016-04-01

    Atherogenic dyslipidemia is common in type 2 diabetes (T2DM) and predicts cardiovascular disease, but information on the association of its components with atherosclerosis is scarce. We aimed to assess differences in the lipoprotein profile in newly-diagnosed T2DM and matched control individuals and their associations with preclinical carotid atherosclerosis. In a case-control study, we evaluated lipoprotein profiles by nuclear magnetic resonance (NMR) spectroscopy and determined carotid intima-media thickness (IMT) and plaque presence (IMT ≥1.5 mm) by B-mode ultrasonography. We assessed 96 T2DM patients (median age 63 years, 44% women, 19% smokers, 54% hypertension, 38% dyslipidemia) and 90 non-diabetic controls matched for age, sex, and cardiovascular risk factors. In T2DM VLDL-particles (mainly large and enriched in cholesterol and triglycerides) were increased, and large HDL-particles (enriched in triglycerides and depleted in cholesterol) were reduced (p lipoprotein profile identifies lipid abnormalities associated with newly-diagnosed T2DM and preclinical atherosclerosis that are not captured by the traditional lipid profile. At this early stage of diabetes, NMR lipoproteins could be useful to identify candidates for a more comprehensive cardiovascular risk prevention strategy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  4. A Quantitative Theoretical Framework For Protein-Induced Fluorescence Enhancement-Förster-Type Resonance Energy Transfer (PIFE-FRET).

    Science.gov (United States)

    Lerner, Eitan; Ploetz, Evelyn; Hohlbein, Johannes; Cordes, Thorben; Weiss, Shimon

    2016-07-01

    Single-molecule, protein-induced fluorescence enhancement (PIFE) serves as a molecular ruler at molecular distances inaccessible to other spectroscopic rulers such as Förster-type resonance energy transfer (FRET) or photoinduced electron transfer. In order to provide two simultaneous measurements of two distances on different molecular length scales for the analysis of macromolecular complexes, we and others recently combined measurements of PIFE and FRET (PIFE-FRET) on the single molecule level. PIFE relies on steric hindrance of the fluorophore Cy3, which is covalently attached to a biomolecule of interest, to rotate out of an excited-state trans isomer to the cis isomer through a 90° intermediate. In this work, we provide a theoretical framework that accounts for relevant photophysical and kinetic parameters of PIFE-FRET, show how this framework allows the extraction of the fold-decrease in isomerization mobility from experimental data, and show how these results provide information on changes in the accessible volume of Cy3. The utility of this model is then demonstrated for experimental results on PIFE-FRET measurement of different protein-DNA interactions. The proposed model and extracted parameters could serve as a benchmark to allow quantitative comparison of PIFE effects in different biological systems.

  5. Brain metabolite changes on proton magnetic resonance spectroscopy in children with poorly controlled type 1 diabetes mellitus

    Energy Technology Data Exchange (ETDEWEB)

    Sarac, K.; Alkan, A.; Baysal, T. [Inonu University School of Medicine, Department of Radiology, Malatya (Turkey); Akinci, A.; Aslan, M. [Inonu University School of Medicine, Department of Paediatric Endocrinology, Malatya (Turkey); Oezcan, C. [Inonu University School of Medicine, Department of Neurology, Malatya (Turkey)

    2005-07-01

    The metabolite changes in the brains of children with poorly controlled type 1 diabetes mellitus (DM) were investigated by proton magnetic resonance spectroscopy (MRS). A total of 30 subjects and 14 age-matched healthy volunteers underwent single-voxel MRS (TE: 136). The duration of disease, medication, presence of hypoglycaemia episodes and the level of haemoglobin A1C (HbA1C) in the patients were noted. Voxels were placed in the pons, left basal ganglion (LBG) and left posterior parietal white matter (PPWM). N-acetylaspartate (NAA)/creatinine (Cr) and choline (Cho)/Cr ratios were calculated. The average HbA1c level was 11.9{+-}3.4 (8.2-19.4). The average number of keto-acidosis episodes was 1.9{+-}2.2 (0-9) and the average number of daily insulin injections was 2.8{+-}0.97 (2-4). MRS revealed lower NAA/Cr and Cho/Cr ratios in the pons and lower NAA/Cr ratio in the PPWM of patients with DM than in control subjects. No significant correlation was observed between the number of hypoglycaemia episodes and metabolite ratios. Metabolic abnormalities have been observed by MRS in the brain of poorly controlled type 1 DM children. These metabolic changes, in particular in the pons region, include a decrease in NAA, indicating neuronal loss or functional impairment, and likely explanations for a decrease in Cho may be dynamic changes in membrane lipids and/or decreased membrane turnover. (orig.)

  6. A numerical study on the feasibility evaluation of a hybrid type superconducting fault current limiter applying thyristors

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Seok Ho; Lee, Woo Seung; Lee, Ji Ho; Hwang, Young Jin; Ko, Tae Kuk [Yonsei University, Seoul (Korea, Republic of)

    2013-12-15

    Smart fault current controller (SFCC) proposed in our previous work consists of a power converter, a high temperature superconducting (HTS) DC reactor, thyristors, and a control unit [1]. SFCC can limit and control the current by adjusting firing angles of thyristors when a fault occurs. SFCC has complex structure because the HTS DC reactor generates the loss under AC. To use the DC reactor under AC, rectifier that consists of four thyristors is needed and it increases internal resistance of SFCC. For this reason, authors propose a hybrid type superconducting fault current limiter (SFCL). The hybrid type SFCL proposed in this paper consists of a non-inductive superconducting coil and two thyristors. To verify the feasibility of the proposed hybrid type SFCL, simulations about the interaction of the superconducting coil and thyristors are conducted when fault current flows in the superconducting coil. Authors expect that the hybrid type SFCL can control the magnitude of the fault current by adjusting the firing angles of thyristors after the superconducting coil limits the fault current at first peak.

  7. Microstrip Resonator for High Field MRI with Capacitor-Segmented Strip and Ground Plane

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Boer, Vincent; Petersen, Esben Thade

    2017-01-01

    ) segmenting stripe and ground plane of the resonator with series capacitors. The design equations for capacitors providing symmetric current distribution are derived. The performance of two types of segmented resonators are investigated experimentally. To authors’ knowledge, a microstrip resonator, where both......, strip and ground plane are capacitor-segmented, is shown here for the first time....

  8. Assessing Metabolism and Injury in Acute Human Traumatic Brain Injury with Magnetic Resonance Spectroscopy: Current and Future Applications

    Directory of Open Access Journals (Sweden)

    Matthew G. Stovell

    2017-09-01

    Full Text Available Traumatic brain injury (TBI triggers a series of complex pathophysiological processes. These include abnormalities in brain energy metabolism; consequent to reduced tissue pO2 arising from ischemia or abnormal tissue oxygen diffusion, or due to a failure of mitochondrial function. In vivo magnetic resonance spectroscopy (MRS allows non-invasive interrogation of brain tissue metabolism in patients with acute brain injury. Nuclei with “spin,” e.g., 1H, 31P, and 13C, are detectable using MRS and are found in metabolites at various stages of energy metabolism, possessing unique signatures due to their chemical shift or spin–spin interactions (J-coupling. The most commonly used clinical MRS technique, 1H MRS, uses the great abundance of hydrogen atoms within molecules in brain tissue. Spectra acquired with longer echo-times include N-acetylaspartate (NAA, creatine, and choline. NAA, a marker of neuronal mitochondrial activity related to adenosine triphosphate (ATP, is reported to be lower in patients with TBI than healthy controls, and the ratio of NAA/creatine at early time points may correlate with clinical outcome. 1H MRS acquired with shorter echo times produces a more complex spectrum, allowing detection of a wider range of metabolites.31 P MRS detects high-energy phosphate species, which are the end products of cellular respiration: ATP and phosphocreatine (PCr. ATP is the principal form of chemical energy in living organisms, and PCr is regarded as a readily mobilized reserve for its replenishment during periods of high utilization. The ratios of high-energy phosphates are thought to represent a balance between energy generation, reserve and use in the brain. In addition, the chemical shift difference between inorganic phosphate and PCr enables calculation of intracellular pH.13 C MRS detects the 13C isotope of carbon in brain metabolites. As the natural abundance of 13C is low (1.1%, 13C MRS is typically performed following

  9. Surface barrier effect on magnetization of a current-carrying type-II superconductor

    Science.gov (United States)

    Genenko, Yu. A.; Freyhardt, H. C.

    2000-10-01

    Vortex penetration in and exit from ideal flux-filled current-carrying superconductors are studied in the frame of the modified Meissner state model accounting for the vortex interactions with the sample surface, transport current, external field and the other vortices inside the sample. The generalized Silsbee's rule is first formulated and the M- H diagram of ideal current-carrying superconductors in a parallel field is estimated which is irreversible due to the surface effect alone. In general, magnetic behaviour of superconductors is shown to be more reversible in the presence of a transport current.

  10. Method for calculating coolant resonance frequencies under normal and accident conditions in nuclear power plants with WWER-type pressurized water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Proskuryakov, K.N. (Moskovskij Ehnergeticheskij Inst. (USSR))

    1983-03-01

    Mathematical models are proposed for calculating acoustic oscillation resonance frequencies in the coolant in various components of the WWER type primary circuit (core, steam generator, pressurizer, piping). Due to the correspondence between model calculations and experimental results obtained in operating nuclear power plants, the developed models can be used for practical calculations. The possibility of calculating the eigenfrequencies of the coolant oscillation under different operating conditions leads to the interpretation of operational data, to the analysis of operational conditions, to the detection of coolant boiling in the reactor, and to design changes in order to prevent resonance oscillations within the coolant.

  11. Past and current perspective on new therapeutic targets for Type-II diabetes.

    Science.gov (United States)

    Patil, Pradip D; Mahajan, Umesh B; Patil, Kalpesh R; Chaudhari, Sandip; Patil, Chandragouda R; Agrawal, Yogeeta O; Ojha, Shreesh; Goyal, Sameer N

    2017-01-01

    Loss of pancreatic β-cell function is a hallmark of Type-II diabetes mellitus (DM). It is a chronic metabolic disorder that results from defects in both insulin secretion and insulin action. Recently, United Kingdom Prospective Diabetes Study reported that Type-II DM is a progressive disorder. Although, DM can be treated initially by monotherapy with oral agent; eventually, it may require multiple drugs. Additionally, insulin therapy is needed in many patients to achieve glycemic control. Pharmacological approaches are unsatisfactory in improving the consequences of insulin resistance. Single therapeutic approach in the treatment of Type-II DM is unsuccessful and usually a combination therapy is adopted. Increased understanding of biochemical, cellular and pathological alterations in Type-II DM has provided new insight in the management of Type-II DM. Knowledge of underlying mechanisms of Type-II DM development is essential for the exploration of novel therapeutic targets. Present review provides an insight into therapeutic targets of Type-II DM and their role in the development of insulin resistance. An overview of important signaling pathways and mechanisms in Type-II DM is provided for the better understanding of disease pathology. This review includes case studies of drugs that are withdrawn from the market. The experience gathered from previous studies and knowledge of Type-II DM pathways can guide the anti-diabetic drug development toward the discovery of clinically viable drugs that are useful in Type-II DM.

  12. Study on Recovery Performance of High Tc Superconducting Tapes for Resistive Type Superconducting Fault Current Limiter Applications

    Science.gov (United States)

    kar, Soumen; Kulkarni, Sandeep; Dixit, Manglesh; Singh, Kuwar Pal; Gupta, Alok; Balasubramanyam, P. V.; Sarangi, S. K.; Rao, V. V.

    Recent advances in reliable production of long length high temperature superconducting (HTS) tapes have resulted in commercial application of superconducting fault current limiters (SFCLs) in electrical utility networks. SFCL gives excellent technical performance when compared to conventional fault current limiters. The fast self-recovery from normal state to superconducting state immediately after the fault removal is an essential criterion for resistive type SFCL operation. In this paper, results on AC over-current testing of 1st generation (1G) Bi2223 tapes and 2nd generation (2G) YBCO coated conductors operating at 77 K are reported. From these results, the recovery time is estimated for different available HTS tapes in the market. The current limiting tests have also been performed to study the effective current limitation. Further, the recovery characteristics after the current limitation are quantitatively discussed for repetitive faults for different time intervals in the range of 100 ms to few seconds.

  13. Effects of Losartan on L-type Calcium Current in Hypertrophied RatMyocytes

    Institute of Scientific and Technical Information of China (English)

    FuLiying; LiYang; ChengLan; WangFang; XiaGuojin; YaoWeixing

    2001-01-01

    Objective To investigate the alterations of L-type calcium current (IcaL) in abdominal aorticligation-induced hypertrophied rat hearts and the effect of losartan on these alterations. METHODS Cardiachypertrophy was induced by abdominal aortic ligation in rats. To record IcaL, whole-cell patch-clamp technique wasused. RESULTS Membrane capacitance was larger in hypertrophied cells (148±29 pF) than in sham-operated cells(102±14 pF, P<0.01) and losartan-treated cells (118±27, P<0.01). The maximal peak IcaL Was increased from-835±124 pA in sham-operated cells to -1404+_417 pA in hypertrophied cells (P<0.01), the corresponding IcaL density was increased from -7.5±1.8 pA.pF1 to -10.5±2.2 pA.pF1 (P<0.01), while they were reduced to -956-2:170pF (P<0.01) and -8.2±1.6 pA.pF1 (P<0.05) respectively in losartan-treated cells. The membrane potential of halfmaximal activation of the hypertrophied cells (-20.6±1.0 mV) shifted to more negative potentials than sham-operatedcells (-15.6±1.6 mV, P<0.01) and lorsartan-treated cells (-17.4±1.0 mV, P<0.01). The slope of the activation curveof hypertrophied cells (5.7±0.4) was decreased slightly than sham-operated cells (6.4±0.5, P<0.05). The membranepotential of half maximal inactivation of hypertrophied cells (-27.6±1.9 mV) shifted to more positive potentials thansham-operated cells (-31.4±2.2 mV, P<0.05). The slope of inactivation curves were not different in the three groups.

  14. Current Status of Management in Type 2 Diabetes Mellitus at General Hospitals in South Korea

    Directory of Open Access Journals (Sweden)

    Jin-Hee Jung

    2015-08-01

    Full Text Available BackgroundIn Korea, the prevalence, complications, and mortality rate of diabetes are rapidly increasing. However, investigations on the actual condition of diabetes management are very limited due to lack of nation-wide research or multicenter study. Hence, we have minutely inquired the current status of diabetes management and achievement of glucose target goal in general hospital offering education program. That way, we are able to furnish data for policy making of diabetes education and draw up guideline which may allow us to reduce the morbidity and mortality of diabetes.MethodsThe subjects consisted of 2,610 patients with type 2 diabetes who visited the 13 general hospital in Seoul or Gyeonggi region from March 19 to May 29, 2013. General characteristics, associated diseases, complications, and management status were investigated.ResultsThe mean age was 61.0±11.6 years, body mass index was 25.0±3.3 kg/m2, and family history of diabetes was 50.5%. The mean duration of diabetes was 10.7±7.9 years and 53% received education about diabetes. The prevalence of hypertension and dyslipidemia were 59.2% and 65.5%, respectively, and 18.3% of the subjects were accompanied by liver disease. Diabetic retinopathy appeared in 31.6%, nephropathy in 28.1%, and neuropathy in 19.9% of the subjects. The mean glycosylated hemoglobin (HbA1c level was 7.3%±1.3% and the achieving rate based on Korean Diabetes Association guideline (HbA1c <6.5% was 24.8%, blood pressure (130/80 mm Hg or less was 49.4%, and low density lipoprotein cholesterol (<100 mg/dL was 63.6%. The reaching rate to the target level in four parameters (blood glucose, blood pressure, lipids, and body weight was 7.8%.ConclusionThe blood glucose control rate was lower than other parameters, and the implementation rate of diabetes education was only 53%. Thus more appropriate glucose control and systematic diabetes education are imperative.

  15. Orexin-A potentiates L-type calcium/barium currents in rat retinal ganglion cells.

    Science.gov (United States)

    Liu, F; Weng, S-J; Yang, X-L; Zhong, Y-M

    2015-10-01

    Two neuropeptides, orexin-A and orexin-B (also called hypocretin-1 and -2), have been implicated in sleep/wake regulation, feeding behaviors via the activation of two subtypes of G-protein-coupled receptors: orexin 1 and orexin 2 receptors (OX1R and OX2R). While the expression of orexins and orexin receptors is immunohistochemically revealed in retinal neurons, the function of these peptides in the retina is largely unknown. Using whole-cell patch-clamp recordings in rat retinal slices, we demonstrated that orexin-A increased L-type-like barium currents (IBa,L) in ganglion cells (GCs), and the effect was blocked by the selective OX1R antagonist SB334867, but not by the OX2R antagonist TCS OX2 29. The orexin-A effect was abolished by intracellular dialysis of GDP-β-S/GPAnt-2A, a Gq protein inhibitor, suggesting the mediation of Gq. Additionally, during internal dialysis of the phosphatidylinositol (PI)-phospholipase C (PLC) inhibitor U73122, orexin-A did not change the IBa,L of GCs, whereas the orexin-A effect persisted in the presence of the phosphatidylcholine (PC)-PLC inhibitor D609. The orexin-A-induced potentiation was not seen with internal infusion of Ca(2+)-free solution or when inositol 1,4,5-trisphosphate (IP3)-sensitive Ca(2+) release from intracellular stores was blocked by heparin/xestospongins-C. Moreover, the orexin-A effect was mimicked by the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate, but was eliminated when PKC was inhibited by bisindolylmaleimide IV (Bis-IV)/Gö6976. Neither adenosine 3',5'-cyclic monophosphate (cAMP)-protein kinase A (PKA) nor guanosine 3',5'-cyclic monophosphate (cGMP)-protein kinase G (PKG) signaling pathway was likely involved, as orexin-A persisted to potentiate the IBa,L of GCs no matter these two pathways were activated or inhibited. These results suggest that, by activating OX1R, orexin-A potentiates the IBa,L of rat GCs through a distinct Gq/PI-PLC/IP3/Ca(2+)/PKC signaling pathway.

  16. Analysis and design of grid-current-feedback active damping for LCL resonance in grid-connected voltage source converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    the grid-side inductor, and the use of a high-pass filter with a negative sign shapes the virtual impedance by an RL damper paralleled by a negative inductance. It is further found that such a negative virtual inductance plays a critical role in mitigating the phase lag caused by the time delay...... in a digital control system. The instability induced by the negative virtual resistance, which is commonly experienced in the feedback-type active damping, can thus be avoided. A systematic design method of the highpass filter is also proposed by the help of root locus analysis in the discrete z-domain. Lastly...

  17. The role of hyperpolarization-activated cationic current in spike-time precision and intrinsic resonance in cortical neurons in vitro.

    Science.gov (United States)

    Gastrein, Philippe; Campanac, Emilie; Gasselin, Célia; Cudmore, Robert H; Bialowas, Andrzej; Carlier, Edmond; Fronzaroli-Molinieres, Laure; Ankri, Norbert; Debanne, Dominique

    2011-08-01

    Hyperpolarization-activated cyclic nucleotide modulated current (I(h)) sets resonance frequency within the θ-range (5–12 Hz) in pyramidal neurons. However, its precise contribution to the temporal fidelity of spike generation in response to stimulation of excitatory or inhibitory synapses remains unclear. In conditions where pharmacological blockade of I(h) does not affect synaptic transmission, we show that postsynaptic h-channels improve spike time precision in CA1 pyramidal neurons through two main mechanisms. I(h) enhances precision of excitatory postsynaptic potential (EPSP)--spike coupling because I(h) reduces peak EPSP duration. I(h) improves the precision of rebound spiking following inhibitory postsynaptic potentials (IPSPs) in CA1 pyramidal neurons and sets pacemaker activity in stratum oriens interneurons because I(h) accelerates the decay of both IPSPs and after-hyperpolarizing potentials (AHPs). The contribution of h-channels to intrinsic resonance and EPSP waveform was comparatively much smaller in CA3 pyramidal neurons. Our results indicate that the elementary mechanisms by which postsynaptic h-channels control fidelity of spike timing at the scale of individual neurons may account for the decreased theta-activity observed in hippocampal and neocortical networks when h-channel activity is pharmacologically reduced.

  18. 基于电流镜的电流型PUF电路设计%Design of current type PUF based on current mirror

    Institute of Scientific and Technical Information of China (English)

    张学龙; 汪鹏君; 张跃军

    2013-01-01

    By researching the Physical Unclonable Functions (PUF) and the current mirror,a current type PUF based on current mirror is proposed.Firstly,multipath currents are generated from multiple current mirrors.Then,two path currents are chosen as the input of the current type sense amplifier.After comparing the two currents,it outputs a random state.Following the fully custom flow,PUF is designed in SMIC 65nm technology and the minimum layout area of the PUF cell is 2.59μm×l.51μm.The outputs of the PUF are analyzed via Monte Carlo simulations under various supply voltages and temperatures by the tool of Spectre.Randomness and robustness of the PUF are observed from the experiment results.It can be effectively used for secret key generation and device authentication.%通过对物理不可克隆函数(Physical Unclonable Functions,PUF)电路和电流镜的研究,提出一种基于电流镜的电流型PUF电路设计方案.该方案首先利用多路电流镜产生随机电流,然后使用电流型敏感放大器比较两路电流的大小,最后产生随机的输出响应.在SMIC 65nm工艺下,利用全定制方法设计PUF电路,在最小尺寸下PUF单元的版图面积为2.59μm× 1.51 μm.通过Spectre软件,在不同电压、温度等工作环境下进行Monte Carlo仿真验证,分析PUF电路的识别能力.实验结果表明所设计的PUF电路逻辑功能正确,且具有良好的随机性和稳定性,可广泛应用于密钥产生和设备认证等领域.

  19. Spin-Density-Wave-Type Ordering of LaCoGe Revealed by 59Co- and 139La-Nuclear Magnetic Resonance Measurements

    Science.gov (United States)

    Karube, Kosuke; Hattori, Taisuke; Ishida, Kenji; Tamura, Nobuhiko; Deguchi, Kazuhiko; Sato, Noriaki K.

    2013-08-01

    The low-temperature magnetic properties of LaCoGe with the tetragonal CeFeSi-type structure were investigated by 59Co- and 139La-nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. The nuclear spin--lattice relaxation rate divided by the temperature, 1/(T1T), gradually increases with decreasing temperature and shows a kink at approximately 18 K, below which an inhomogeneous internal field appears at the Co nuclear site. These results indicate that antiferromagnetic ordering occurs below TN˜ 18 K. However, an internal field was not observed at the La nuclear site below TN. Taking all NMR results into account, we conclude that spin-density-wave (SDW)-type ordering occurs, where magnetic correlations are of the checkerboard type [\\mbi{Q}=(π,π)] in the ab-plane and have a long periodicity along the c-axis with inhomogeneous ordered moments pointing to the c-axis.

  20. Current opportunities and challenges of magnetic resonance spectroscopy, positron emission tomography, and mass spectrometry imaging for mapping cancer metabolism in vivo.

    Science.gov (United States)

    Lin, Gigin; Chung, Yuen-Li

    2014-01-01

    Cancer is known to have unique metabolic features such as Warburg effect. Current cancer therapy has moved forward from cytotoxic treatment to personalized, targeted therapies, with some that could lead to specific metabolic changes, potentially monitored by imaging methods. In this paper we addressed the important aspects to study cancer metabolism by using image techniques, focusing on opportunities and challenges of magnetic resonance spectroscopy (MRS), dynamic nuclear polarization (DNP)-MRS, positron emission tomography (PET), and mass spectrometry imaging (MSI) for mapping cancer metabolism. Finally, we highlighted the future possibilities of an integrated in vivo PET/MR imaging systems, together with an in situ MSI tissue analytical platform, may become the ultimate technologies for unraveling and understanding the molecular complexities in some aspects of cancer metabolism. Such comprehensive imaging investigations might provide information on pharmacometabolomics, biomarker discovery, and disease diagnosis, prognosis, and treatment response monitoring for clinical medicine.

  1. Qualification of Fin-Type Heat Exchangers for the ITER Current Leads

    CERN Document Server

    Ballarino, A; Bordini, B; Devred, A; Ding, K; Niu, E; Sitko, M; Taylor, T; Yang, Y; Zhou, T

    2015-01-01

    The ITER current leads will transfer large currents of up to 68 kA into the biggest superconducting magnets ever built. Following the development of prototypes and targeted trials of specific manufacturing processes through mock-ups, the ASIPP (Chinese Institute of Plasma Physics) is preparing for the series fabrication. A key component of the ITER HTS current leads are the resistive heat exchangers. Special R&D was conducted for these components at CERN and ASIPP in support of their designs. In particular several mock-ups were built and tested in room temperature gas to measure the dynamic pressure drop and compare to 3D CFD models.

  2. Calculations using the circuit equation for current and field distributions of type II superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Tominaka, Toshiharu [Ministry of Education, Culture, Sports, Science and Technology (MEXT), 2-5-1, Marunouchi, Chiyoda-ku, Tokyo 100-8959 (Japan)

    2006-10-15

    The current distributions of untwisted infinitely long superconductors have been studied during the current sweep and under an external field, using the inductance matrix among superconducting finite elements which are generated from a superconductor. The self- and mutual inductances of general polygonal conductors with a uniform current density over each cross section are precisely calculated from the analytical expressions for the geometrical mean distances. The current distributions among each superconducting element are obtained by solving the circuit equation with the Bean model and a nonlinear E-J relation based on the power law. In addition, the magnetic field and vector potential distributions of an untwisted superconducting composite are also obtained, using the analytical expressions for the magnetic field and vector potential due to polygonal conductors.

  3. Nuclear magnetic resonance-determined lipoprotein subclasses and carotid intima-media thickness in type 1 diabetes.

    Science.gov (United States)

    Basu, Arpita; Jenkins, Alicia J; Zhang, Ying; Stoner, Julie A; Klein, Richard L; Lopes-Virella, Maria F; Garvey, W Timothy; Lyons, Timothy J

    2016-01-01

    Dyslipidemia has been linked to vascular complications of Type 1 diabetes (T1DM). We investigated the prospective associations of nuclear magnetic resonance-determined lipoprotein subclass profiles (NMR-LSP) and conventional lipid profiles with carotid intima-media thickness (IMT) in T1DM. NMR-LSP and conventional lipids were measured in a subset of Diabetes Control and Complications Trial (DCCT) participants (n = 455) at study entry ('baseline', 1983-89), and were related to carotid IMT determined by ultrasonography during the observational follow-up of the DCCT, the Epidemiology of Diabetes Interventions and Complications (EDIC) study, at EDIC Year 12 (2004-2006). Associations were defined using multiple linear regression stratified by gender, and following adjustment for HbA1c, diabetes duration, body mass index, albuminuria, DCCT randomization group, smoking status, statin use, and ultrasound devices. In men, significant positive associations were observed between some baseline NMR-subclasses of LDL (total IDL/LDL and large LDL) and common and/or internal carotid IMT, and between conventional total- and LDL-cholesterol and non-HDL-cholesterol and common carotid IMT, at EDIC Year 12; these persisted in adjusted analyses (p < 0.05). Large LDL particles and conventional triglycerides were positively associated with common carotid IMT changes over 12 years (p < 0.05). Inverse associations of mean HDL diameter and large HDL concentrations, and positive associations of small LDL with common and/or internal carotid IMT (all p < 0.05) were found, but did not persist in adjusted analyses. No significant associations were observed in women. NMR-LSP-derived LDL particles, in addition to conventional lipid profiles, may help in identifying men with T1DM at highest risk for vascular disease. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  4. Quantitative and qualitative differences in subcutaneous adipose tissue stores across lipodystrophy types shown by magnetic resonance imaging

    Directory of Open Access Journals (Sweden)

    Little Cynthia

    2007-03-01

    Full Text Available Abstract Background Lipodystrophies are characterized by redistributed subcutaneous fat stores. We previously quantified subcutaneous fat by magnetic resonance imaging (MRI in the legs of two patients with familial partial lipodystrophy subtypes 2 and 3 (FPLD2 and FPLD3, respectively. We now extend the MRI analysis across the whole body of patients with different forms of lipodystrophy. Methods We studied five subcutaneous fat stores (supraclavicular, abdominal, gluteal, thigh and calf and the abdominal visceral fat stores in 10, 2, 1, 1 and 2 female subjects with, respectively, FPLD2, FPLD3, HIV-related partial lipodystrophy (HIVPL, acquired partial lipodystrophy (APL, congenital generalized lipodystrophy (CGL and in six normal control subjects. Results Compared with normal controls, FPLD2 subjects had significantly increased supraclavicular fat, with decreased abdominal, gluteal, thigh and calf subcutaneous fat. FPLD3 subjects had increased supraclavicular and abdominal subcutaneous fat, with less severe reductions in gluteal, thigh and calf fat compared to FPLD2 subjects. The repartitioning of fat in the HIVPL subject closely resembled that of FPLD3 subjects. APL and CGL subjects had reduced upper body, gluteal and thigh subcutaneous fat; the APL subject had increased, while CGL subjects had decreased subcutaneous calf fat. Visceral fat was markedly increased in FPLD2 and APL subjects. Conclusion Semi-automated MRI-based adipose tissue quantification indicates differences between various lipodystrophy types in these studied clinical cases and is a potentially useful tool for extended quantitative phenomic analysis of genetic metabolic disorders. Further studies with a larger sample size are essential for confirming these preliminary findings.

  5. Computation of a Single-phase Shell-Type Transformer Windings Forces Caused by Inrush and Short-circuit Currents

    Directory of Open Access Journals (Sweden)

    M. B.B. Sharifian

    2008-01-01

    Full Text Available This research studies the forces on the windings of transformer due to inrush current. These forces are compared with the corresponding forces due to short-circuit of the windings. Two-dimensional finite element computation of a single-phase shell-type transformer is carried out based on the maximum permissible inrush current value where its amplitude is the same as the rated short-circuit current. To verify the computation results, they are compared with those recently obtained using Artificial Neural Network (ANN.

  6. Influence of the optical fiber type on the performances of fiber-optics current sensor dedicated to plasma current measurement in ITER.

    Science.gov (United States)

    Aerssens, Matthieu; Descamps, Frédéric; Gusarov, Andrei; Mégret, Patrice; Moreau, Philippe; Wuilpart, Marc

    2015-07-01

    In this paper, we compare, by means of simulations using the Jones formalism, the performances of several optical fiber types (low birefringence and spun fibers) for the measurement of plasma current in international thermonuclear experimental reactor (ITER). The main results presented in this paper concern the minimum value of the ratio between the beat length and the spun period, which allows meeting the ITER current measurement specifications. Assuming a high-birefringence spun fiber with a beat length of 3 mm, we demonstrate that the minimum ratio between the beat length and the spun period is 4.4 when considering a 28 m long sensing fiber surrounding the vacuum vessel. This minimum ratio rises to 10.14 when a 100 m long lead fiber connecting the interrogating system to the sensing fiber is taken into account.

  7. Realization of cavity linewidth narrowing via interacting dark resonances in a tripod-type electromagnetically induced transparency system

    CERN Document Server

    Ying, Kang; Chen, Dijun; Cai, Haiwen; Qu, Ronghui

    2014-01-01

    Cavity linewidth narrowing via double-dark resonances has been experimentally observed using the 87Rb Zeeman splitting sublevels. With the steep dispersion led by the interacting dark resonances in the tripodtype electromagnetically induced transparency system, we narrow the cavity linewidth to 250 KHz at room temperature. Furthermore, the position of this ultranarrow cavity linewidth could be tuned in a 60 MHz coupling field detuning range.

  8. Is current serologic RhD typing of blood donors sufficient for avoiding immunization of recipients?

    DEFF Research Database (Denmark)

    Krog, Grethe Risum; Clausen, Frederik Banch; Berkowicz, Adela

    2011-01-01

    Avoiding immunization with clinically important antibodies is a primary objective in transfusion medicine. Therefore, it is central to identify the extent of D antigens that escape routine RhD typing of blood donors and to improve methodology if necessary.......Avoiding immunization with clinically important antibodies is a primary objective in transfusion medicine. Therefore, it is central to identify the extent of D antigens that escape routine RhD typing of blood donors and to improve methodology if necessary....

  9. T-type feedback network applied in resonance frequency locking of resonator fiber optic gyro%T型反馈网络在谐振式光纤陀螺频率锁定中的应用

    Institute of Scientific and Technical Information of China (English)

    李圣昆; 郑永秋; 安盼龙; 李小枫; 陈浩; 焦新泉; 刘俊; 闫树斌

    2014-01-01

    谐振式光纤陀螺(R-FOG)的频率锁定是陀螺信号检测的关键技术,尤其在长时间的测试中,谐振频率的锁定稳定度决定了陀螺的输出性能。根据光纤环形谐振腔的传输理论,分析了其谐振特性及其一次谐波特性;搭建了R-FOG测试系统,采用正弦波相位调制解调技术实现谐振谱线一次谐波的输出;在分析由运算放大器构成的传统模拟比例积分(PI)电路的漂移误差源的基础上,给出了可以有效抑制漂移误差的T型反馈网络,应用到谐振式光纤陀螺的谐振频率锁定中,得到了较好的锁定效果,经Allan方差分析,谐振频率长时间(4000 s)的锁定稳定度优于9×10-12。%For resonator fiber optic gyro ( R-FOG ) , resonance frequency locking is a key technique at detecting the gyro signal . The stability of resonance frequency locking determines the output performance of the gyro , especially in the long-term test . According to the transmission theory of fiber ring resonator ( FRR ) , the resonance characteristics and the first harmonic were analyzed; the R-FOG system was set up . The first harmonic demodulation signal derive from the experiments using the sine wave phase modulation technique; the drift errors of traditional analog proportional -integral PI consisting of operational amplifiers were analyzed . On this basis , T-type feedback network was applied in resonance frequency locking of R-FOG . The drift error was suppressed effectively and better result was obtained. The stability of resonance frequency locking for 4 000 s is superior to 9 ×10-12 by Allan variance analysis.

  10. Serotonin Regulates the Firing of Principal Cells of the Subiculum by Inhibiting a T-type Ca(2+) Current

    DEFF Research Database (Denmark)

    Petersen, Anders V; Jensen, Camilla S; Crépel, Valérie

    2017-01-01

    and calcium imaging, we demonstrate that 5-HT2C receptors reduce bursting activity by inhibiting a low-threshold calcium current mediated by T-type Ca(2+) channels in principal cells of the subiculum. In addition, we show that the activation of this novel pathway decreases bursting activity and the occurrence...

  11. A Measurement of the Effective Electron Neutral Current Coupling Parameters from Polarized Bhabha Scattering at the Z0 Resonance

    Energy Technology Data Exchange (ETDEWEB)

    Langston, Matthew D

    2003-07-15

    The effective electron neutral current coupling parameters, {bar g}{sub V}{sup 3} and {bar g}{sub A}{sup c}, have been measured from analyzing 43,222 polarized Bhabha scattered events (e{sup +}e{sup -} {yields} e{sup +}e{sup -}) using the SLAC Large Detector (SLD) experiment at the Stanford Linear Accelerator Center (SLAC). The SLAC Linear Collider (SLC) produced the Bhabha scattered events by colliding polarized electrons, with an average polarization of 74%, with unpolarized positrons at an average center-of-mass energy of 91.25 GeV. The analysis used the entire SLD data sample collected between 1994 and 1998 (the last year the SLD detector collected data). The results are {bar g}{sub V}{sup e} = -0.0469 {+-} 0.0024 (stat.) {+-} 0.0004 (sys.); {bar g}{sub A}{sup e} = -0.5038 {+-} 0.0010 (stat.) {+-} 0.0043 (sys.). All Bhabha scattered events within the angular acceptance of the SLD calorimeter subsystems were used in this analysis, including both small-angle events (28 mrad. {le} theta {le} 68 mrad.) measured by the Silicon/Tungsten Luminosity Monitor (LUM), and large angle events (0 {le} |cos{theta}| {le} 0.9655) measured by the Liquid Argon Calorimeter (LAC). Using all of the data in this manner allows for the high-precision measurement of the luminosity provided by the LUM to constrain the uncertainty on {bar g}{sub V}{sup e} and {bar g}{sub A}{sup e}. The measured integrated luminosity for the combined 1993 through 1998 SLD data sample is L{sub Integrated} = 19,247 {+-} 17 (stat.) {+-} 146 (sys.) nb{sup -1}. In contrast with other SLD precision measurements of the effective weak mixing angle, which are sensitive to the ratio {bar g}{sub V}{sup e}/{bar g}{sub A}{sup e}, this result independently determines {bar g}{sub V}{sup 3} and {bar g}{sub A}{sup c}. The analysis techniques to measure {bar g}{sub V}{sup 3} and {bar g}{sub A}{sup c} are described, and the results are compared with other SLD measurements as well as other experiments.

  12. Lysophosphatidic acid increases the electrophysiological instability of adult rabbit ventricular myocardium by augmenting L-type calcium current.

    Directory of Open Access Journals (Sweden)

    Yong Wei

    Full Text Available Lysophosphatidic acid (LPA has diverse actions on the cardiovascular system and is widely reported to modulate multiple ion currents in some cell types. However, little is known about its electrophysiological effects on cardiac myocytes. This study investigated whether LPA has electrophysiological effects on isolated rabbit myocardial preparations. The results indicate that LPA prolongs action potential duration at 90% repolarization (APD(90 in a concentration- and frequency-dependent manner in isolated rabbit ventricular myocytes. The application of extracellular LPA significantly increases the coefficient of APD(90 variability. LPA increased L-type calcium current (I(Ca,L density without altering its activation or deactivation properties. In contrast, LPA has no effect on two other ventricular repolarizing currents, the transient outward potassium current (I(to and the delayed rectifier potassium current (I(K. In arterially perfused rabbit left ventricular wedge preparations, the monophasic action potential duration, QT interval, and Tpeak-end are prolonged by LPA. LPA treatment also significantly increases the incidence of ventricular tachycardia induced by S(1S(2 stimulation. Notably, the effects of LPA on action potentials and I(Ca,L are PTX-sensitive, suggesting LPA action requires a G(i-type G protein. In conclusion, LPA prolongs APD and increases electrophysiological instability in isolated rabbit myocardial preparations by increasing I(Ca,L in a G(i protein-dependent manner.

  13. A use-dependent sodium current modification induced by type I pyrethroid insecticides in honeybee antennal olfactory receptor neurons.

    Science.gov (United States)

    Kadala, Aklesso; Charreton, Mercedes; Jakob, Ingrid; Le Conte, Yves; Collet, Claude

    2011-06-01

    We studied the mode of action of type I pyrethroids on the voltage-dependent sodium current from honeybee olfactory receptor neurons (ORNs), whose proper function in antenna is crucial for interindividual communication in this species. Under voltage-clamp, tetramethrin and permethrin induce a long lasting TTX-sensitive tail current upon repolarization, which is the hallmark of an abnormal prolongation of the open channel configuration. Permethrin and tetramethrin also slow down the sodium current fast inactivation. Tetramethrin and permethrin both bind to the closed state of the channel as suggested by the presence of an obvious tail current after the first single depolarization applied in the presence of either compounds. Moreover, at first sight, channel opening seems to promote tetramethrin and permethrin binding as evidenced by the progressive tail current summation along with trains of stimulations, tetramethrin being more potent at modifying channels than permethrin. However, a use-dependent increase in the sodium peak current along with stimulations suggests that the tail current accumulation could also be a consequence of progressively unmasked silent channels. Experiments with the sea anemone toxin ATX-II that suppresses sodium channels fast inactivation are consistent with the hypothesis that these silent channels are either in an inactivated state at rest, or that they normally inactivate before they open so that they do not participate to the control sodium current. In honeybee ORNs, three processes lead to a use-dependent pyrethroid-induced tail current accumulation: (i) a recruitment of silent channels that produces an increase in the peak sodium current, (ii) a slowing down of the sodium current inactivation produced by prolongation of channels opening and (iii) a typical deceleration in current deactivation. The use-dependent recruitment of silent sodium channels in honeybee ORNs makes pyrethroids more potent at modifying neuronal excitability.

  14. Anomalous Fluctuations of Currents in Sinai-Type Random Chains with Strongly Correlated Disorder

    Science.gov (United States)

    Oshanin, Gleb; Rosso, Alberto; Schehr, Grégory

    2013-03-01

    We study properties of a random walk in a generalized Sinai model, in which a quenched random potential is a trajectory of a fractional Brownian motion with arbitrary Hurst parameter H, 0segment of length L of such a chain decay as L-(1-H), independently of k, which suggests that despite a logarithmic confinement the average current is much higher than its Fickian counterpart in homogeneous systems. Our results reveal a paradoxical behavior such that, for fixed n and L, the mean-square displacement decreases when one varies H from 0 to 1, while the average current increases. This counterintuitive behavior is explained via an analysis of representative realizations of disorder.

  15. Phytobioactive compound-based nanodelivery systems for the treatment of type 2 diabetes mellitus - current status.

    Science.gov (United States)

    Ganesan, Palanivel; Arulselvan, Palanisamy; Choi, Dong-Kug

    2017-01-01

    Type 2 diabetes mellitus (T2DM) is a major chronic disease that is prevalent worldwide, and it is characterized by an increase in blood glucose, disturbances in the metabolism, and alteration in insulin secretion. Nowadays, food-based therapy has become an important treatment mode for type 2 diabetes, and phytobioactive compounds have gained an increasing amount of attention to this end because they have an effect on multiple biological functions, including the sustained secretion of insulin and regeneration of pancreatic islets cells. However, the poor solubility and lower permeability of these phyto products results in a loss of bioactivity during processing and oral delivery, leading to a significant reduction in the bioavailability of phytobioactive compounds to treat T2DM. Recently, nanotechnological systems have been developed for use as various types of carrier systems to improve the delivery of bioactive compounds and thus obtain a greater bioavailability. Furthermore, carrier systems in most nanodelivery systems are highly biocompatible, with nonimmunologic behavior, a high degree of biodegradability, and greater mucoadhesive strength. Therefore, this review focuses on the various types of nanodelivery systems that can be used for phytobioactive compounds in treating T2DM with greater antidiabetic effects. There is also additional focus on improving the effects of various phytobioactive compounds through nanotechnological delivery to ensure a highly efficient treatment of type 2 diabetes.

  16. Current data with inulin-type fructans and calcium, targeting bone health in adults.

    Science.gov (United States)

    Coxam, Véronique

    2007-11-01

    In humans, there is increasing evidence that the colon can absorb nutritionally significant amounts of calcium, and this process may be susceptible to dietary manipulation by fermentable substrates, especially inulin-type fructans. Inulin-type fructans can modulate calcium absorption because they are resistant to hydrolysis by mammalian enzymes and are fermented in the large intestine to produce short-chain fatty acids, which in turn reduce luminal pH and modify calcium speciation, and hence solubility, or exert a direct effect on the mucosal transport pathway. Quite a few intervention studies showed an improvement of calcium absorption in adolescents or young adults by inulin-type fructans. In the same way, a positive effect has been reported in older women.

  17. DNA typing in forensic medicine and in criminal investigations: a current survey

    Science.gov (United States)

    Benecke, Mark

    Since 1985 DNA typing of biological material has become one of the most powerful tools for personal identification in forensic medicine and in criminal investigations [1-6]. Classical DNA 〝fingerprinting'' is increasingly being replaced by polymerase chain reaction (PCR) based technology which detects very short polymorphic stretches of DNA [7-15]. DNA loci which forensic scientists study do not code for proteins, and they are spread over the whole genome [16, 17]. These loci are neutral, and few provide any information about individuals except for their identity. Minute amounts of biological material are sufficient for DNA typing. Many European countries are beginning to establish databases to store DNA profiles of crime scenes and known offenders. A brief overview is given of past and present DNA typing and the establishment of forensic DNA databases in Europe.

  18. Current position of vasoconstrictor and albumin infusion for type 1 hepatorenal syndrome

    Institute of Scientific and Technical Information of China (English)

    Abhasnee; Sobhonslidsuk

    2015-01-01

    Spontaneous bacterial peritonitis(SBP),refractory ascites,hepatorenal syndrome(HRS),hyponatremia and hepatic encephalopathy are complicationswhich frequently happen during a clinical course of decompensated cirrhosis.Splanchnic and peripheral vasodilatation,increased intrarenal vasoconstriction and impaired cardiac responsive function are pathological changes causing systemic and hemodynamic derangement.Extreme renal vasoconstriction leads to severe reduction of renal blood flow and glomerular filtration rate,which finally evolves into the clinical feature of HRS.Clinical manifestations of type 1 and type 2 HRS come to medical attention differently.Patients with type1 HRS present as acute kidney injury whereas those with type 2 HRS will have refractory ascites as the leading problem.Prompt diagnosis of type 1 HRS can halt the progression of HRS to acute tubular necrosis if the combined treatment of albumin infusion and vasoconstrictors is started timely.HRS reversal was seen in 34%-60%of patients,followed with decreasing mortality.Baseline serum levels of creatinine less than5 mg/dL,bilirubin less than 10 mg/dL,and increased mean arterial pressure of over 5 mmHg by day 3 of the combined treatment of vasoconstrictor and albumin are the predictors of good response.Type 1 HRS can be prevented in some conditions such as albumin infusion in SBP,prophylactic antibiotics for upper gastrointestinal hemorrhage,albumin replacement after large volume paracentesis in cirrhotic patients with massive ascites.The benefit of albumin infusion in infection with primary source other than SBP requires more studies.

  19. Six types of multistability in a neuronal model based on slow calcium current.

    Directory of Open Access Journals (Sweden)

    Tatiana Malashchenko

    Full Text Available BACKGROUND: Multistability of oscillatory and silent regimes is a ubiquitous phenomenon exhibited by excitable systems such as neurons and cardiac cells. Multistability can play functional roles in short-term memory and maintaining posture. It seems to pose an evolutionary advantage for neurons which are part of multifunctional Central Pattern Generators to possess multistability. The mechanisms supporting multistability of bursting regimes are not well understood or classified. METHODOLOGY/PRINCIPAL FINDINGS: Our study is focused on determining the bio-physical mechanisms underlying different types of co-existence of the oscillatory and silent regimes observed in a neuronal model. We develop a low-dimensional model typifying the dynamics of a single leech heart interneuron. We carry out a bifurcation analysis of the model and show that it possesses six different types of multistability of dynamical regimes. These types are the co-existence of 1 bursting and silence, 2 tonic spiking and silence, 3 tonic spiking and subthreshold oscillations, 4 bursting and subthreshold oscillations, 5 bursting, subthreshold oscillations and silence, and 6 bursting and tonic spiking. These first five types of multistability occur due to the presence of a separating regime that is either a saddle periodic orbit or a saddle equilibrium. We found that the parameter range wherein multistability is observed is limited by the parameter values at which the separating regimes emerge and terminate. CONCLUSIONS: We developed a neuronal model which exhibits a rich variety of different types of multistability. We described a novel mechanism supporting the bistability of bursting and silence. This neuronal model provides a unique opportunity to study the dynamics of networks with neurons possessing different types of multistability.

  20. Quantitative analysis of the reconstruction errors of the currently popular algorithm of magnetic resonance electrical property tomography at the interfaces of adjacent tissues.

    Science.gov (United States)

    Duan, Song; Xu, Chao; Deng, Guanhua; Wang, Jiajia; Liu, Feng; Xin, Sherman Xuegang

    2016-06-01

    This work quantitatively analyzed the reconstruction errors (REs) of electrical property (EP) images using a currently popular algorithm of magnetic resonance electrical property tomography (MREPT), which occurred along the tissue interfaces. Transmitted magnetic fields B1+ were acquired at 3 T using a birdcage coil loaded with a phantom consisting of various adjacent tissues. Homogeneous Helmholtz was employed to calculate the EP maps by Laplacian computation of central differences. The maps of absolute REs (aREs) and relative REs (rREs) were calculated. The maximum and mean rREs, in addition to rRE distributions at the interfaces, were presented. Reconstructed EP maps showed various REs along different interface boundaries. Among all the investigated tissue interfaces, the kidney-fat interface presented the maximum mean rREs for both conductivity and relative permittivity. The minimum mean rRE of conductivity was observed at the spleen-muscle interface, and the minimum mean rRE of relative permittivity was detected along the lung-heart interface. The mean rREs ranged from 0.3986 to 36.11 for conductivity and 0.2218 to 11.96 for relative permittivity. Overall, this research indicates that different REs occur at various tissue boundaries, as shown by the currently popular algorithm of MREPT. Thus, REs should be considered when applying MREPT to reconstruct the EP distributions inside the human body. Copyright © 2016 John Wiley & Sons, Ltd.

  1. Magnetic resonance imaging findings of periosteal interposition in a distal tibial Salter-Harris type I fracture with surgical correlation: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nara; Jung, Jee Young; Kang, Ki Ser [Chung-Ang University Hospital, Seoul (Korea, Republic of)

    2013-08-15

    The complication of growth disturbance after physeal fracture of the distal tibia has been well recognized. Although irreducible fractures of the physis due to trapped soft tissue, including periosteum, are not common, it could still cause growth disturbances. Therefore, the detection of periosteal interposition with physeal injury on imaging study is important. We present a case of a 10-year-old girl with surgically confirmed periosteal interposition in the distal tibial Salter-Harris type I fracture, through magnetic resonance imaging findings.

  2. Type 2 Endoleaks Post-EVAR: Current Evidence for Rupture Risk, Intervention and Outcomes of Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Raymond, E-mail: rchung@doctors.org.uk; Morgan, Robert A., E-mail: Robert.Morgan@stgeorges.nhs.uk [St. George’s Healthcare NHS Trust, Radiology, Ground Floor, St. James Wing (United Kingdom)

    2015-06-15

    Type 2 endoleaks (EL2) are the most commonly encountered endoleaks following EVAR. Despite two decades of experience, there remains considerable variation in the management of EL2 with controversies ranging from if to treat, when to treat and how to treat. Here, we summarise the available evidence, describe the treatment techniques available and offer guidelines for management.

  3. Molecular Epidemiologic Typing Systems of Bacterial Pathogens: Current Issues and Perpectives

    Directory of Open Access Journals (Sweden)

    Marc J Struelens

    1998-09-01

    Full Text Available The epidemiologic typing of bacterial pathogens can be applied to answer a number of different questions: in case of outbreak, what is the extent and mode of transmission of epidemic clone(s ? In case of long-term surveillance, what is the prevalence over time and the geographic spread of epidemic and endemic clones in the population? A number of molecular typing methods can be used to classify bacteria based on genomic diversity into groups of closely-related isolates (presumed to arise from a common ancestor in the same chain of transmission and divergent, epidemiologically-unrelated isolates (arising from independent sources of infection. Ribotyping, IS-RFLP fingerprinting, macrorestriction analysis of chromosomal DNA and PCR-fingerprinting using arbitrary sequence or repeat element primers are useful methods for outbreak investigations and regional surveillance. Library typing systems based on multilocus sequence-based analysis and strain-specific probe hybridization schemes are in development for the international surveillance of major pathogens like Mycobacterium tuberculosis. Accurate epidemiological interpretation of data obtained with molecular typing systems still requires additional research on the evolution rate of polymorphic loci in bacterial pathogens.

  4. Gentamicin Blocks the ACh-Induced BK Current in Guinea Pig Type II Vestibular Hair Cells by Competing with Ca2+ at the l-Type Calcium Channel

    Directory of Open Access Journals (Sweden)

    Hong Yu

    2014-04-01

    Full Text Available Type II vestibular hair cells (VHCs II contain big-conductance Ca2+-dependent K+ channels (BK and L-type calcium channels. Our previous studies in guinea pig VHCs II indicated that acetylcholine (ACh evoked the BK current by triggering the influx of Ca2+ ions through l-type Ca2+ channels, which was mediated by M2 muscarinic ACh receptor (mAChRs. Aminoglycoside antibiotics, such as gentamicin (GM, are known to have vestibulotoxicity, including damaging effects on the efferent nerve endings on VHCs II. This study used the whole-cell patch clamp technique to determine whether GM affects the vestibular efferent system at postsynaptic M2-mAChRs or the membrane ion channels. We found that GM could block the ACh-induced BK current and that inhibition was reversible, voltage-independent, and dose-dependent with an IC50 value of 36.3 ± 7.8 µM. Increasing the ACh concentration had little influence on GM blocking effect, but increasing the extracellular Ca2+ concentration ([Ca2+]o could antagonize it. Moreover, 50 µM GM potently blocked Ca2+ currents activated by (--Bay-K8644, but did not block BK currents induced by NS1619. These observations indicate that GM most likely blocks the M2 mAChR-mediated response by competing with Ca2+ at the l-type calcium channel. These results provide insights into the vestibulotoxicity of aminoglycoside antibiotics on mammalian VHCs II.

  5. Identification of Magnetizing Inrush and Internal Short-Circuit Fault Current in V/x-Type Traction Transformer

    Directory of Open Access Journals (Sweden)

    Y. H. Li

    2013-01-01

    Full Text Available This paper deals with the fault diagnosis methodology for the V/x-type traction transformer in railway passenger-dedicated lines. A kind of the protection methodology to combine empirical mode decomposition (EMD, energy weight, and information entropy is proposed. This method can sensitively reflect the dynamic information changes of traction transformer differential current, so it can not only effectively identify internal short-circuit fault current from magnetizing inrush but also better identify fault current accompanied with magnetizing inrush. In this method, the differential current is decomposed by EMD and the energy weight of each intrinsic mode function (IMF is calculated, and the feature vector of the fault pattern recognition is obtained by constructing IMF energy entropy. The field-measured data illustrate that the new method not only has the advantages of high sensitivity, faster identification speed, and clear concept but also is available for the diagnosis of the complicated dynamic system.

  6. A New Type Hi-Speed BLDC Control System Base on Indirect Current Control Strategy

    Science.gov (United States)

    Wang, D. P.; Wang, Y. C.; Zhang, F. G.; Jin, S.

    2017-05-01

    High speed BLDC has the characteristic as larger air gap smaller armature inductance, traditional PWM modulation will produce a great number of high frequency current harmonics which led problem like large torque ripple and serious motor heat. In the meantime traditional PWM modulation use the diode rectifier which cause harmonic pollution in electric power net. To solve the problem above, proposes a new motor controller topology. Using the IGBT device to replace the diode on frequency converter rectifier side, apply the power factor correction technology, reduce the pollution on the grid. Using busbar current modulation on the inverter, driving bridge-arm use 3-phase 6-state open as driving Mode, realize the control on a 10000r/min,10kw BLDC. The results of Simulation on matlab show the topological structure as proposed can effectively improve the network side power factor and reduce the motor armature winding harmonic and motor torque ripple.

  7. Low Dark Current Mesa-Type AlGaN Flame Detectors

    Directory of Open Access Journals (Sweden)

    Lung-Chien Chen

    2007-01-01

    Full Text Available This study characterizes and reports on the fabrication process of AlGaN flame photodetectors with an Al0.1Ga0.9N/GaN superlattice structure. The AlGaN flame photodetectors exhibited a low dark current (∼1.17×10−10 A at bias of −5 V and large rejection ratio of photocurrent (∼2.14×10−5 A at bias of -5 V to dark current, which is greater than five orders of magnitude. Responsivity at 350 nm at a bias of -5 V was 0.194 A/W. Quantum efficiency, η, was 0.687 at a reverse bias of 5 V.

  8. Protective Effect of Carvedilol on Abnormality of L-type Calcium Current Induced by Oxygen Free Radical in Cardiomyocytes

    Institute of Scientific and Technical Information of China (English)

    刘念; 喻荣辉; 阮燕菲; 周强; 卜军; 李泱

    2004-01-01

    The protective effect of carvedilol on abnormality of L-type calcium current induced by oxygen free radical in single guinea pig ventricular myocytes was studied. Whole-cell patch clamp technique was used to study the effect of H2 O2 (0.5 mmol/L) on L-type calcium current in single guinea pig ventricular myocytes and the action of pretreatment with carvedilol (0.5 μmol/L). 0.5μmol/L carvedilol had no significant effect on ICa,L and its channel dynamics. In the presence of 0.5 mmol/L H2O2, peak current of ICa,L was reduced significantly (P<0.001), the I-V curve of Ica,L was shifted upward, steady-state activation curve and steady-state deactivation curve of ICa,L were shifted left and recovery time of ICa,L was delayed significantly (P<0. 001). 0. 5 μmol/L carvedilol significantly alleviated the inhibitory effect of H2O2 on ICa,L as compared with that in H2O2 group (P<0.01). In addition, carvedilol reversed the changes of dynamics of ICa,L induced by H2O2. It was concluded that carvedilol could alleviate the abnormality of L-type calcium current induced by oxygen free radical in cardiomyocytes. It shows partly the possible mechanism of the special availability of carvedilol in chronic heart failure.

  9. Forster resonance energy transfer measurements of ryanodine receptor type 1 structure using a novel site-specific labeling method.

    Directory of Open Access Journals (Sweden)

    James D Fessenden

    Full Text Available BACKGROUND: While the static structure of the intracellular Ca(2+ release channel, the ryanodine receptor type 1 (RyR1 has been determined using cryo electron microscopy, relatively little is known concerning changes in RyR1 structure that accompany channel gating. Förster resonance energy transfer (FRET methods can resolve small changes in protein structure although FRET measurements of RyR1 are hampered by an inability to site-specifically label the protein with fluorescent probes. METHODOLOGY/PRINCIPAL FINDINGS: A novel site-specific labeling method is presented that targets a FRET acceptor, Cy3NTA to 10-residue histidine (His tags engineered into RyR1. Cy3NTA, comprised of the fluorescent dye Cy3, coupled to two Ni(2+/nitrilotriacetic acid moieties, was synthesized and functionally tested for binding to His-tagged green fluorescent protein (GFP. GFP fluorescence emission and Cy3NTA absorbance spectra overlapped significantly, indicating that FRET could occur (Förster distance = 6.3 nm. Cy3NTA bound to His(10-tagged GFP, quenching its fluorescence by 88%. GFP was then fused to the N-terminus of RyR1 and His(10 tags were placed either at the N-terminus of the fused GFP or between GFP and RyR1. Cy3NTA reduced fluorescence of these fusion proteins by 75% and this quenching could be reversed by photobleaching Cy3, thus confirming GFP-RyR1 quenching via FRET. A His(10 tag was then placed at amino acid position 1861 and FRET was measured from GFP located at either the N-terminus or at position 618 to Cy3NTA bound to this His tag. While minimal FRET was detected between GFP at position 1 and Cy3NTA at position 1861, 53% energy transfer was detected from GFP at position 618 to Cy3NTA at position 1861, thus indicating that these sites are in close proximity to each other. CONCLUSIONS/SIGNIFICANCE: These findings illustrate the potential of this site-specific labeling system for use in future FRET-based experiments to elucidate novel aspects of RyR1

  10. Development of Simple Dip-Stick-Type Uniaxial Stress Actuator for Alternating-Current Susceptibility Measurements

    Institute of Scientific and Technical Information of China (English)

    MYDEEN Kamal; YU Yong; JIN Chang-Qing

    2008-01-01

    A simple dip-stick type uniaxial stress actuator for ac-susceptibility measurement is designed. Target pressure can be achieved by smooth and continues work carried out using a combination of light weight micrometer and spring.The magnitude of the pressure is directly calculated from the force constant of the spring and the surface area of the sample. Benchmark on the quality of the data under uniaxial pressure is confirmed by the Piezo resistance measurements on [100] oriented n-type Si. The system is examined and calibrated with the standard paramagnetic Gd2O3. Further, the device performance, generation of constant uniaxial pressure against temperature variations,is assured by investigating the ac-magnetic susceptibility measurements on highly anisotropic La1.25 Sr1.75Mn2 O7bilayer single crystal.

  11. [Cation ions modulate the ACh-sensitive current in type II vestibular hair cells of guinea pigs].

    Science.gov (United States)

    Guo, Chang-Kai; Zhang, Song; Kong, Wei-Jia; Li, Qing-Tian; Li, Zhi-Wang

    2006-04-25

    Molecular biological studies and electrophysiological data have demonstrated that acetylcholine (ACh) is the principal cochlear and vestibular efferent neurotransmitter among mammalians. However, the functional roles of ACh in type II vestibular hair cells among mammalians are still unclear, with the exception of the well-known alpha9-containing nicotinic ACh receptor (alpha9-nAChR) in cochlear hair cells and frog saccular hair cells. In this study, the properties of the ACh-sensitive current were investigated by whole-cell patch clamp technique in isolated type II vestibular hair cells of guinea pigs. The direct effect of extracellular ACh was to induce a hyperpolarization effect in type II vestibular hair cells. Type II vestibular hair cells displayed a sustained outward current in response to the perfusion of ACh. It took about 60 s for the ACh-sensitive current to get a complete re-activation. The reversal potential of the ACh-sensitive current was (-66 +/- 8) mV, which indicated that potassium ion was the main carrier of this current. The blocking effect by the submillimolar concentration of tetraethylammonium (TEA) further indicated that extracellular ACh stimulated the calcium-dependent potassium current. Following replacement of the compartment of NaCl in the normal external solution with TrisCl, LiCl or saccharose respectively, the amplitude of the ACh-sensitive current was not affected. Blocking of the release of intracellular Ca(2+) stores by intracellular application of heparin failed to inhibit the ACh-sensitive current. Therefore, extracellular Na(+)and the inositol 1,4,5-trisphosphate (IP(3))-dependent intracellular Ca(2+)release were not involved in the activation of the ACh-sensitive current. However, the ACh-sensitive current was strongly affected by the concentration of the extracellular K(+), extracellular Ca(2+) and intracellular Mg(2+). The amplitude of the ACh- sensitive current was strongly inhibited by high concentration of extracellular K

  12. De novo development of gliomas in a child with neurofibromatosis type 1, fragile X and previously normal brain magnetic resonance imaging

    Science.gov (United States)

    Zafar, Rabia; Hsiao, Esther Y.; Botteron, Kelly N.; McKinstry, Robert C.; Gutmann, David H.

    2016-01-01

    Fifteen to 20% of children with neurofibromatosis type 1 develop low-grade glial neoplasms. However, since neuroimaging is not routinely obtained until a child is clinically symptomatic, little is known about presymptomatic radiographic characteristics of gliomas in this at-risk population. Herein, we describe a child with neurofibromatosis type 1 who initially had normal brain imaging before the development of multifocal gliomas. Comparison of these serial images demonstrated that brain tumors can arise de novo in children with this cancer predisposition syndrome, further underscoring the limited prognostic value of normal baseline magnetic resonance imaging. PMID:26973730

  13. De novo development of gliomas in a child with neurofibromatosis type 1, fragile X and previously normal brain magnetic resonance imaging

    Directory of Open Access Journals (Sweden)

    Rabia Zafar, MD, PhD

    2016-03-01

    Full Text Available Fifteen to 20% of children with neurofibromatosis type 1 develop low-grade glial neoplasms. However, since neuroimaging is not routinely obtained until a child is clinically symptomatic, little is known about presymptomatic radiographic characteristics of gliomas in this at-risk population. Herein, we describe a child with neurofibromatosis type 1 who initially had normal brain imaging before the development of multifocal gliomas. Comparison of these serial images demonstrated that brain tumors can arise de novo in children with this cancer predisposition syndrome, further underscoring the limited prognostic value of normal baseline magnetic resonance imaging.

  14. De novo development of gliomas in a child with neurofibromatosis type 1, fragile X and previously normal brain magnetic resonance imaging.

    Science.gov (United States)

    Zafar, Rabia; Hsiao, Esther Y; Botteron, Kelly N; McKinstry, Robert C; Gutmann, David H

    2016-03-01

    Fifteen to 20% of children with neurofibromatosis type 1 develop low-grade glial neoplasms. However, since neuroimaging is not routinely obtained until a child is clinically symptomatic, little is known about presymptomatic radiographic characteristics of gliomas in this at-risk population. Herein, we describe a child with neurofibromatosis type 1 who initially had normal brain imaging before the development of multifocal gliomas. Comparison of these serial images demonstrated that brain tumors can arise de novo in children with this cancer predisposition syndrome, further underscoring the limited prognostic value of normal baseline magnetic resonance imaging.

  15. Effects of insulin resistance and type 2 diabetes on lipoprotein subclass particle size and concentration determined by nuclear magnetic resonance.

    Science.gov (United States)

    Garvey, W Timothy; Kwon, Soonho; Zheng, Deyi; Shaughnessy, Sara; Wallace, Penny; Hutto, Amy; Pugh, Kimberly; Jenkins, Alicia J; Klein, Richard L; Liao, Youlian

    2003-02-01

    The insulin resistance syndrome (IRS) is associated with dyslipidemia and increased cardiovascular disease risk. A novel method for detailed analyses of lipoprotein subclass sizes and particle concentrations that uses nuclear magnetic resonance (NMR) of whole sera has become available. To define the effects of insulin resistance, we measured dyslipidemia using both NMR lipoprotein subclass analysis and conventional lipid panel, and insulin sensitivity as the maximal glucose disposal rate (GDR) during hyperinsulinemic clamps in 56 insulin sensitive (IS; mean +/- SD: GDR 15.8 +/- 2.0 mg. kg(-1). min(-1), fasting blood glucose [FBG] 4.7 +/- 0.3 mmol/l, BMI 26 +/- 5), 46 insulin resistant (IR; GDR 10.2 +/- 1.9, FBG 4.9 +/- 0.5, BMI 29 +/- 5), and 46 untreated subjects with type 2 diabetes (GDR 7.4 +/- 2.8, FBG 10.8 +/- 3.7, BMI 30 +/- 5). In the group as a whole, regression analyses with GDR showed that progressive insulin resistance was associated with an increase in VLDL size (r = -0.40) and an increase in large VLDL particle concentrations (r = -0.42), a decrease in LDL size (r = 0.42) as a result of a marked increase in small LDL particles (r = -0.34) and reduced large LDL (r = 0.34), an overall increase in the number of LDL particles (r = -0.44), and a decrease in HDL size (r = 0.41) as a result of depletion of large HDL particles (r = 0.38) and a modest increase in small HDL (r = -0.21; all P change in medium or small VLDL), which produced an increase in serum triglycerides; a decrease in LDL size as a result of an increase in small and a reduction in large LDL subclasses, plus an increase in overall LDL particle concentration, which together led to no difference (IS versus IR) or a minimal difference (IS versus diabetes) in LDL cholesterol; and a decrease in large cardioprotective HDL combined with an increase in the small HDL subclass such that there was no net significant difference in HDL cholesterol. We conclude that 1) insulin resistance had profound

  16. Current and Future Clinical Applications of Zinc Transporter-8 in Type 1 Diabetes Mellitus

    Institute of Scientific and Technical Information of China (English)

    Bo Yi; Gan Huang; Zhi-Guang Zhou

    2015-01-01

    Objective:To evaluate the utility of zinc transporter-8 (ZnT8) in the improvement of type 1 diabetes mellitus (T1DM) diagnosis and prediction,and to explore whether ZnT8 is a potential therapeutic target in T l DM.Data Sources:A search was conducted within the medical database PubMed for relevant articles published from 2001 to 2015.The search terms are as follows:"ZnT8," "type 1 diabetes," "latent autoimmune diabetes in adults," "type 2 diabetes," "islet autoantibodies," "zinc supplement," "T cells," "β cell," "immune therapy." We also searched the reference lists of selected articles.Study Selection:English-language original articles and critical reviews concerning ZnT8 and the clinical applications of islet autoantibodies in diabetes were reviewed.Results:The basic function of ZnT8 is maintaining intracellular zinc homeostasis,which modulates the process of insulin biosynthesis,storage,and secretion.Autoantibodies against ZnT8 (ZnT8A) and ZnT8-specific T cells are the reliable biomarkers for the identification,stratification,and characterization ofTl DM.Additionally,the results from the animal models and clinical trials have shown that ZnT8 is a diabetogenic antigen,suggesting the possibility of ZnT8-specific immunotherapy as an alternative for T1DM therapy.Conclusions:ZnT8 is a novel islet autoantigen with a widely potential for clinical applications in T1DM.However,before the large-scale clinical applications,there are still many problems to be solved.

  17. Microwave Resonators and Filters

    Science.gov (United States)

    2015-12-22

    Examples of planar superconducting resonators Superconducting resonators are usually one of two types either planar, or three dimensional most often...also been employed. The term lumped element is used because the resonator comprises separated inductor and capacitor. In superconducting resonators the...implementation often is a miniature version in which the capacitor and inductor are combined in the same structure. Fig. 5 shows an example for CPW

  18. Analytical magnetic torque calculations and experimental testing of radial flux permanent magnet-type eddy current brakes

    Science.gov (United States)

    Choi, Jang-Young; Jang, Seok-Myeong

    2012-04-01

    This paper reports on analytical magnetic torque calculations and experimental tests of a radial flux permanent magnet (RFPM)-type eddy current brake (ECB). Analytical solutions for permanent magnet-generated magnetic fields that consider the eddy current reaction are obtained by using a magnetic vector potential and a two dimensional (2D) polar coordinate system. On the basis of these solutions, the analytical expressions for a magnetic torque are also derived. All analytical results are validated extensively by non-linear finite element calculations. In particular, magnetic torque measurements are obtained in tests to confirm the analyses. Finally, practical issues related to the analytical study of RFPM-type ECBs are fully discussed.

  19. Type 1 diabetes: Awareness, management and challenges: Current scenario in India

    Directory of Open Access Journals (Sweden)

    K M Prasanna Kumar

    2015-01-01

    Full Text Available Type 1 diabetes mellitus (T1DM has a wide presence in children and has a high mortality rates. The disease, if left unmanaged, poses various challenges to the patient and healthcare providers, including development of diabetic complications and thus decreasing the life expectancy of the affected child. The challenges of T1DM include awareness of the disease that is very poor among the general public and also in parents of T1DM children along with the health care professionals. The challenge of lack of awareness of T1DM can be met by increasing public awareness programs, conducting workshops for diabetes educators regarding T1DM in children, newsletters, CMEs, online courses, and by structured teaching modules for diabetes educators. Diagnosis of T1DM was a challenge a few decades ago but the situation has improved today with diagnostic tests and facilities, made available even in villages. Investigation facilities and infrastructure, however, are very poor at the primary care level, especially in rural areas. Insulin availability, acceptability, and affordability are also major problems, compounded by the various types of insulin that are available in the market with a varied price range. But effective use of insulin remains a matter of utmost importance.

  20. Sex and regional differences in rabbit right ventricular L-type calcium current levels and mathematical modelling of arrhythmia vulnerability.

    Science.gov (United States)

    Kalik, Zane M; Mike, Joshua L; Slipski, Cassandra; Wright, Moriah; Jalics, Jozsi Z; Womble, Mark D

    2017-07-01

    What is the central question of this study? Regional variations of ventricular L-type calcium current (ICa-L ) amplitude may underlie the increased arrhythmia risk in adult females. Current amplitude variations have been described for the left ventricle but not for the right ventricle. What is the main finding and its importance? Adult female rabbit right ventricular base myocytes exhibit elevated ICa-L compared with female apex or male myocytes. Oestrogen upregulated ICa-L in cultured female myocytes. Mathematical simulations modelling long QT syndrome type 2 demonstrated that elevated ICa-L prolonged action potentials and induced early after-depolarizations. Thus, ventricular arrhythmias in adult females may be associated with an oestrogen-induced upregulation of ICa-L . Previous studies have shown that adult rabbit left ventricular myocytes exhibit sex and regional differences in L-type calcium current (ICa-L ) levels that contribute to increased female susceptibility to arrhythmogenic early after-depolarizations (EADs). We used patch-clamp recordings from isolated adult male and female rabbit right ventricular myocytes to determine apex-base differences in ICa-L density and used mathematical modelling to examine the contribution of ICa-L to EAD formation. Current density measured at 0 mV in female base myocytes was 67% higher than in male base myocytes and 55% higher than in female apex myocytes. No differences were observed between male and female apex myocytes, between male apex and base myocytes, or in the voltage dependences of ICa-L activation or inactivation. The role of oestrogen was investigated using cultured adult female right ventricular base myocytes. After 2 days, 17β-estradiol (1 nm) produced a 65% increase in ICa-L density compared with untreated control myocytes, suggesting an oestrogen-induced upregulation of ICa-L . Action potential simulations using a modified Luo-Rudy cardiomyocyte model showed that increased ICa-L density, at the level

  1. The skeletal L-type Ca(2+) current is a major contributor to excitation-coupled Ca(2+) entry.

    Science.gov (United States)

    Bannister, Roger A; Pessah, Isaac N; Beam, Kurt G

    2009-01-01

    The term excitation-coupled Ca(2+) entry (ECCE) designates the entry of extracellular Ca(2+) into skeletal muscle cells, which occurs in response to prolonged depolarization or pulse trains and depends on the presence of both the 1,4-dihydropyridine receptor (DHPR) in the plasma membrane and the type 1 ryanodine receptor in the sarcoplasmic reticulum (SR) membrane. The ECCE pathway is blocked by pharmacological agents that also block store-operated Ca(2+) entry, is inhibited by dantrolene, is relatively insensitive to the DHP antagonist nifedipine (1 microM), and is permeable to Mn(2+). Here, we have examined the effects of these agents on the L-type Ca(2+) current conducted via the DHPR. We found that the nonspecific cation channel antagonists (2-APB, SKF 96356, La(3+), and Gd(3+)) and dantrolene all inhibited the L-type Ca(2+) current. In addition, complete (>97%) block of the L-type current required concentrations of nifedipine >10 microM. Like ECCE, the L-type Ca(2+) channel displays permeability to Mn(2+) in the absence of external Ca(2+) and produces a Ca(2+) current that persists during prolonged ( approximately 10-second) depolarization. This current appears to contribute to the Ca(2+) transient observed during prolonged KCl depolarization of intact myotubes because (1) the transients in normal myotubes decayed more rapidly in the absence of external Ca(2+); (2) the transients in dysgenic myotubes expressing SkEIIIK (a DHPR alpha(1S) pore mutant thought to conduct only monovalent cations) had a time course like that of normal myotubes in Ca(2+)-free solution and were unaffected by Ca(2+) removal; and (3) after block of SR Ca(2+) release by 200 microM ryanodine, normal myotubes still displayed a large Ca(2+) transient, whereas no transient was detectable in SkEIIIK-expressing dysgenic myotubes. Collectively, these results indicate that the skeletal muscle L-type channel is a major contributor to the Ca(2+) entry attributed to ECCE.

  2. The Skeletal L-type Ca2+ Current Is a Major Contributor to Excitation-coupled Ca2+ entry

    Science.gov (United States)

    Bannister, Roger A.; Pessah, Isaac N.; Beam, Kurt G.

    2009-01-01

    The term excitation-coupled Ca2+ entry (ECCE) designates the entry of extracellular Ca2+ into skeletal muscle cells, which occurs in response to prolonged depolarization or pulse trains and depends on the presence of both the 1,4-dihydropyridine receptor (DHPR) in the plasma membrane and the type 1 ryanodine receptor in the sarcoplasmic reticulum (SR) membrane. The ECCE pathway is blocked by pharmacological agents that also block store-operated Ca2+ entry, is inhibited by dantrolene, is relatively insensitive to the DHP antagonist nifedipine (1 μM), and is permeable to Mn2+. Here, we have examined the effects of these agents on the L-type Ca2+ current conducted via the DHPR. We found that the nonspecific cation channel antagonists (2-APB, SKF 96356, La3+, and Gd3+) and dantrolene all inhibited the L-type Ca2+ current. In addition, complete (>97%) block of the L-type current required concentrations of nifedipine >10 μM. Like ECCE, the L-type Ca2+ channel displays permeability to Mn2+ in the absence of external Ca2+ and produces a Ca2+ current that persists during prolonged (∼10-second) depolarization. This current appears to contribute to the Ca2+ transient observed during prolonged KCl depolarization of intact myotubes because (1) the transients in normal myotubes decayed more rapidly in the absence of external Ca2+; (2) the transients in dysgenic myotubes expressing SkEIIIK (a DHPR α1S pore mutant thought to conduct only monovalent cations) had a time course like that of normal myotubes in Ca2+-free solution and were unaffected by Ca2+ removal; and (3) after block of SR Ca2+ release by 200 μM ryanodine, normal myotubes still displayed a large Ca2+ transient, whereas no transient was detectable in SkEIIIK-expressing dysgenic myotubes. Collectively, these results indicate that the skeletal muscle L-type channel is a major contributor to the Ca2+ entry attributed to ECCE. PMID:19114636

  3. Liver fibrosis in type I Gaucher disease: magnetic resonance imaging, transient elastography and parameters of iron storage.

    Directory of Open Access Journals (Sweden)

    Anneloes E Bohte

    Full Text Available Long term liver-related complications of type-1 Gaucher disease (GD, a lysosomal storage disorder, include fibrosis and an increased incidence of hepatocellular carcinoma. Splenectomy has been implicated as a risk factor for the development of liver pathology in GD. High ferritin concentrations are a feature of GD and iron storage in Gaucher cells has been described, but iron storage in the liver in relation to liver fibrosis has not been studied. Alternatively, iron storage in GD may be the result of iron supplementation therapy or regular blood transfusions in patients with severe cytopenia. In this pilot study, comprising 14 type-1 GD patients (7 splenectomized, 7 non-splenectomized and 7 healthy controls, we demonstrate that liver stiffness values, measured by Transient Elastography and MR-Elastography, are significantly higher in splenectomized GD patients when compared with non-splenectomized GD patients (p = 0.03 and p = 0.01, respectively. Liver iron concentration was elevated (>60±30 µmol/g in 4 GD patients of whom 3 were splenectomized. No relationship was found between liver stiffness and liver iron concentration. HFE gene mutations were more frequent in splenectomized (6/7 than in non-splenectomized (2/7 participants (p = 0.10. Liver disease appeared more advanced in splenectomized than in non-splenectomized patients. We hypothesize a relationship with excessive hepatic iron accumulation in splenectomized patients. We recommend that all splenectomized patients, especially those with evidence of substantial liver fibrosis undergo regular screening for HCC, according to current guidelines.

  4. Current and future constraints on Bekenstein-type models for varying couplings

    CERN Document Server

    Leite, A C O

    2016-01-01

    Astrophysical tests of the stability of dimensionless fundamental couplings, such as the fine-structure constant $\\alpha$ and the proton-to-electron mass ratio $\\mu$, are an optimal probe of new physics. There is a growing interest in these tests, following indications of possible spacetime variations at the few parts per million level. Here we make use of the latest astrophysical measurements, combined with background cosmological observations, to obtain improved constraints on Bekenstein-type models for the evolution of both couplings. These are arguably the simplest models allowing for $\\alpha$ and $\\mu$ variations, and are characterized by a single free dimensionless parameter, $\\zeta$, describing the coupling of the underlying dynamical degree of freedom to the electromagnetic sector. In the former case we find that this parameter is constrained to be $|\\zeta_\\alpha|<4.8\\times10^{-6}$ (improving previous constraints by a factor of 6), while in the latter (which we quantitatively compare to astrophysic...

  5. Satisfaction rates with the current Special Type Consultation (STC) reimbursement scheme among General Practitioners – A Mixed Methods Study.

    LENUS (Irish Health Repository)

    Kiely, A

    2017-03-01

    The Special Type Consultation (STC) scheme is a fee-for-service reimbursement scheme for General Practitioners (GPs) in Ireland. Introduced in 1989, the scheme includes specified patient services involving the application of a learned skill, e.g. suturing. This study aims to establish the extent to which GPs believe this scheme is appropriate for current General Practice. This is an embedded mixed-methods study combining quantitative data on GPs working experience of and qualitative data on GPs attitudes towards the scheme. Data were collected by means of an anonymous postal questionnaire. The response rate was 60.4% (n=159.) Twenty-nine percent (n=46) disagreed and 65% (n=104) strongly disagreed that the current list of special items is satisfactory. Two overriding themes were identified: economics and advancement of the STC process. This study demonstrates an overwhelming consensus among GPs that the current STC scheme is outdated and in urgent need of revision to reflect modern General Practice.

  6. Current limiting behavior in three-phase transformer-type SFCLs using an iron core according to variety of fault

    Science.gov (United States)

    Cho, Yong-Sun; Jung, Byung-Ik; Ha, Kyoung-Hun; Choi, Soo-Geun; Park, Hyoung-Min; Choi, Hyo-Sang

    To apply the superconducting fault current limiter (SFCL) to the power system, the reliability of the fault-current-limiting operation must be ensured in diverse fault conditions. The SFCL must also be linked to the operation of the high-speed recloser in the power system. In this study, a three-phase transformer-type SFCL, which has a neutral line to improve the simultaneous quench characteristics of superconducting elements, was manufactured to analyze the fault-current-limiting characteristic according to the single, double, and triple line-to-ground faults. The transformer-type SFCL, wherein three-phase windings are connected to one iron core, reduced the burden on the superconducting element as the superconducting element on the sound phase was also quenched in the case of the single line-to-ground fault. In the case of double or triple line-to-ground faults, the flux from the faulted phase winding was interlinked with other faulted or sound phase windings, and the fault-current-limiting rate decreased because the windings of three phases were inductively connected by one iron core.

  7. Hydrodynamic Performance Analysis on Different Airfoils of Straight Blade H Type of Vertical Axis Tidal Current Energy Turbine

    Directory of Open Access Journals (Sweden)

    Kan Kan

    2016-01-01

    Full Text Available Airfoil is a key factor that influences the hydrodynamic performance of vertical axis tidal current energy turbine. In order to explore the influences from the runner’s blade airfoil towards its hydrodynamic performance, three-dimensional unsteady flow numerical simulation on four airfoils of straight blade H type of tidal current energy turbines was carried out, under the precondition of same turbine compactness. Through investigating the influences from the four different airfoils of H blade towards the runner in terms of its dynamic torque feature and hydropower utilization coefficient, this research has analyzed the hydrodynamic performance of the tidal current energy turbine. As the research result indicates, the maximum dynamic torque value of the single-blade turbine with NACA0015 airfoil is significantly higher than that of the other three airfoils; while the maximum value of the overall runner torque is determined by the operating conditions such as different stream speed etc. As a whole, hydropower utilization coefficient of the turbine with asymmetric airfoil NACA4415 is better than that of the other three airfoils. This research has provided references for the design and airfoil selection for the new type of tidal current energy turbine.

  8. Current indicators of nutritional care in children with type 1 diabetes in India: Do we need a national nutritional guideline?

    Directory of Open Access Journals (Sweden)

    Sanjay Kalra

    2017-01-01

    Full Text Available Background: Nutrition is an important pillar of management in children with type 1 diabetes. Indian food is heavily influenced by region, religion, traditions, seasons, and cultural choices. This survey was done to assess current practices and the need for India specific nutritional guidelines for children with type 1 diabetes. Materials and Methods: Two 12-item questionnaires were administered to forty health-care professionals across India. The first questionnaire evaluated current clinical practice indicators for nutrition in these children and second assessed practices for counseling a child on dietary habits. Results: There is great heterogeneity across the country with regard to dietary advice offered to children with type 1 diabetes. 97.5% of the respondents feel there is a need for an Indian dietary guideline for children with type 1 diabetes. Conclusion: There is need of India specific nutritional guidelines that should be made considering key variants such as age, region, cultural preference, economic burden and psychosocial beliefs, to offer guidance to diabetes care professionals.

  9. Mechanism of accelerated current decay caused by an episodic ataxia type-1-associated mutant in a potassium channel pore.

    Science.gov (United States)

    Peters, Christian J; Werry, Daniel; Gill, Hira S; Accili, Eric A; Fedida, David

    2011-11-30

    In Kv1.1, single point mutants found below the channel activation gate at residue V408 are associated with human episodic ataxia type-1, and impair channel function by accelerating decay of outward current during periods of membrane depolarization and channel opening. This decay is usually attributed to C-type inactivation, but here we provide evidence that this is not the case. Using voltage-clamp fluorimetry in Xenopus oocytes, and single-channel patch clamp in mouse ltk- cells, of the homologous Shaker channel (with the equivalent mutation V478A), we have determined that the mutation may cause current decay through a local effect at the activation gate, by destabilizing channel opening. We demonstrate that the effect of the mutant is similar to that of trapped 4-aminopyridine in antagonizing channel opening, as the mutation and 10 mm 4-AP had similar, nonadditive effects on fluorescence recorded from the voltage-sensitive S4 helix. We propose a model where the Kv1.1 activation gate fails to enter a stabilized open conformation, from which the channel would normally C-type inactivate. Instead, the lower pore lining helix is able to enter an activated-not-open conformation during depolarization. These results provide an understanding of the molecular etiology underlying episodic ataxia type-1 due to V408A, as well as biophysical insights into the links between the potassium channel activation gate, the voltage sensor and the selectivity filter.

  10. Current understanding of the processes underlying the triggering of and energy loss associated with type I ELMs

    CERN Document Server

    Kirk, A; Dunne, M; Huijsmans, G; Pamela, S; Becoulet, M; Harrison, J R; Hillesheim, J; Roach, C; Saarelma, S

    2013-01-01

    The type I ELMy H-mode is the baseline operating scenario for ITER. While it is known that the type I ELM ultimately results from the peeling-ballooning instability, there is growing experimental evidence that a mode grows up before the ELM crash that may modify the edge plasma, which then leads to the ELM event due to the peeling-ballooning mode. The triggered mode results in the release of a large number of particles and energy from the core plasma but the precise mechanism by which these losses occur is still not fully understood and hence makes predictions for future devices uncertain. Our current understanding of the processes that trigger type I ELMs and the size of the resultant energy loss are reviewed and compared to experimental data and ideas for further development are discussed.

  11. Site-dependent cobalt electronic state in La-Co co-substituted magnetoplumbite-type ferrite: (59)Co nuclear magnetic resonance study.

    Science.gov (United States)

    Nakamura, Hiroyuki; Shimoda, Aiko; Waki, Takeshi; Tabata, Yoshikazu; Mény, Christian

    2016-09-01

    The nuclear magnetic resonance of (59)Co was measured over a wide frequency range in a powder sample crushed from a well-characterized single crystal of La-Co co-substituted magnetoplumbite-type strontium ferrite (SrFe12O19), a familiar base material for the ferrite permanent magnet. The simultaneous observation of both high- and low-frequency resonances suggests the coexistence of both high- and low-spin states of the substituted Co or the presence of Co orbital moment at a particular site. The possible presence of trivalent Co was also investigated. The results suggest that the Co atoms are distributed across different crystallographic sites with different local environments, and that the electronic state of Co is much more subtle than the conventional understanding.

  12. Type 2 diabetes mellitus in Malaysia: current trends and risk factors.

    Science.gov (United States)

    Tee, E-S; Yap, R W K

    2017-07-01

    This review discussed the prevalence of diabetes mellitus (DM) in Malaysia and the associated major risk factors, namely overweight/obesity, dietary practices and physical activity in both adults and school children. Detailed analyses of such information will provide crucial information for the formulation and implementation of programmes for the control and prevention of T2DM in the country. National studies from 1996-2015, and other recent nation-wide studies were referred to. The current prevalence of DM in 2015 is 17.5%, over double since 1996. Females, older age group, Indians, and urban residents had the highest risk of DM. The combined prevalence of overweight/obesity in 2015 is 47.7% for adults. Adults did not achieve the recommended intakes for majority of the foods groups in the Malaysian Food Pyramid especially fruits and vegetables. Adults also had moderate physical activity level. Three nation-wide studies showed a prevalence ranging from 27 to 31% for combined overweight/obesity in school children. The prevalence was higher among boys, primary school age, Indian ethnicity, and even rural children are not spared. Physical activity level was also low among school children. There must be serious systematic implementation of action plans to combat the high prevalence of diabetes and associated risk factors.

  13. Shaking the Tree: Multi-locus Sequence Typing Usurps Current Onchocercid (Filarial Nematode) Phylogeny

    Science.gov (United States)

    Lefoulon, Emilie; Bourret, Jérôme; Junker, Kerstin; Guerrero, Ricardo; Cañizales, Israel; Kuzmin, Yuriy; Satoto, Tri Baskoro T.; Cardenas-Callirgos, Jorge Manuel; de Souza Lima, Sueli; Raccurt, Christian; Mutafchiev, Yasen; Gavotte, Laurent; Martin, Coralie

    2015-01-01

    During the past twenty years, a number of molecular analyses have been performed to determine the evolutionary relationships of Onchocercidae, a family of filarial nematodes encompassing several species of medical or veterinary importance. However, opportunities for broad taxonomic sampling have been scarce, and analyses were based mainly on 12S rDNA and coxI gene sequences. While being suitable for species differentiation, these mitochondrial genes cannot be used to infer phylogenetic hypotheses at higher taxonomic levels. In the present study, 48 species, representing seven of eight subfamilies within the Onchocercidae, were sampled and sequences of seven gene loci (nuclear and mitochondrial) analysed, resulting in the hitherto largest molecular phylogenetic investigation into this family. Although our data support the current hypothesis that the Oswaldofilariinae, Waltonellinae and Icosiellinae subfamilies separated early from the remaining onchocercids, Setariinae was recovered as a well separated clade. Dirofilaria, Loxodontofilaria and Onchocerca constituted a strongly supported clade despite belonging to different subfamilies (Onchocercinae and Dirofilariinae). Finally, the separation between Splendidofilariinae, Dirofilariinae and Onchocercinae will have to be reconsidered. PMID:26588229

  14. Reading fluency estimates of current intellectual function: demographic factors and effects of type of stimuli.

    Science.gov (United States)

    Simos, Panagiotis G; Sideridis, Georgios D; Kasselimis, Dimitrios; Mouzaki, Angeliki

    2013-03-01

    The study explores the potential clinical value of reading fluency measures in complementing demographic variables as indices of current intellectual capacity. IQ estimates (based on the PPVT-R, WASI Vocabulary and Block Design subtests) were obtained from a representative, non-clinical sample of 386 Greek adults aged 48–87 years along with two measures of reading efficiency (one involving relatively high-frequency words—WRE—and the second comprised of phonotactically matched pseudowords—PsWRE). Both reading measures (number of items read correctly in 45 s) accounted for significant portions of variability in demographically adjusted verbal and performance IQ indices. Reading measures provided IQ estimates which were significantly closer to those predicted by demographic variables alone in up to 22% of individuals with fewer than 7 (across all ages) or 13 years of formal education (in the 70–87 year age range). PsWRE scores slightly outperformed WRE scores in predicting a person’s estimated verbal or performance IQ. Results are discussed in the context of previous findings using reading accuracy measures for low-frequency words with exceptional spellings in less transparent orthographic systems such as English.

  15. A microprocessor-based multichannel subsensory stochastic resonance electrical stimulator.

    Science.gov (United States)

    Chang, Gwo-Ching

    2013-01-01

    Stochastic resonance electrical stimulation is a novel intervention which provides potential benefits for improving postural control ability in the elderly, those with diabetic neuropathy, and stroke patients. In this paper, a microprocessor-based subsensory white noise electrical stimulator for the applications of stochastic resonance stimulation is developed. The proposed stimulator provides four independent programmable stimulation channels with constant-current output, possesses linear voltage-to-current relationship, and has two types of stimulation modes, pulse amplitude and width modulation.

  16. Mathematical Modeling of Subthreshold Resonant Properties in Pyloric Dilator Neurons

    OpenAIRE

    Vazifehkhah Ghaffari, Babak; Kouhnavard, Mojgan; Aihara, Takeshi; Kitajima, Tatsuo

    2015-01-01

    Various types of neurons exhibit subthreshold resonance oscillation (preferred frequency response) to fluctuating sinusoidal input currents. This phenomenon is well known to influence the synaptic plasticity and frequency of neural network oscillation. This study evaluates the resonant properties of pacemaker pyloric dilator (PD) neurons in the central pattern generator network through mathematical modeling. From the pharmacological point of view, calcium currents cannot be blocked in PD neur...

  17. Cognitive performance, psychological well-being, and brain magnetic resonance imaging in older patients with type 1 diabetes.

    NARCIS (Netherlands)

    Brands, A.M.; Kessels, R.P.C.; Hoogma, R.P.L.M.; Henselmans, J.M.L.; Beek-Boter, J.W. van der; Kappelle, L.J.; Haan, E.H.F. de; Biessels, G.J.

    2006-01-01

    Modest cognitive impairment has been reported in young-adult patients with type 1 diabetes. In older patients with type 2 diabetes, cognitive impairments are more pronounced, which might be due to age but also to differential effects of type 1 diabetes and type 2 diabetes on the brain. This study th

  18. Current state of type 1 diabetes immunotherapy: incremental advances, huge leaps, or more of the same?

    Science.gov (United States)

    Phillips, Brett; Trucco, Massimo; Giannoukakis, Nick

    2011-01-01

    Thus far, none of the preclinically successful and promising immunomodulatory agents for type 1 diabetes mellitus (T1DM) has conferred stable, long-term insulin independence to diabetic patients. The majority of these immunomodulators are humanised antibodies that target immune cells or cytokines. These as well as fusion proteins and inhibitor proteins all share varying adverse event occurrence and severity. Other approaches have included intact putative autoantigens or autoantigen peptides. Considerable logistical outlays have been deployed to develop and to translate humanised antibodies targeting immune cells, cytokines, and cytokine receptors to the clinic. Very recent phase III trials with the leading agent, a humanised anti-CD3 antibody, call into question whether further development of these biologics represents a step forward or more of the same. Combination therapies of one or more of these humanised antibodies are also being considered, and they face identical, if not more serious, impediments and safety issues. This paper will highlight the preclinical successes and the excitement generated by phase II trials while offering alternative possibilities and new translational avenues that can be explored given the very recent disappointment in leading agents in more advanced clinical trials.

  19. Current State of Type 1 Diabetes Immunotherapy: Incremental Advances, Huge Leaps, or More of the Same?

    Directory of Open Access Journals (Sweden)

    Brett Phillips

    2011-01-01

    Full Text Available Thus far, none of the preclinically successful and promising immunomodulatory agents for type 1 diabetes mellitus (T1DM has conferred stable, long-term insulin independence to diabetic patients. The majority of these immunomodulators are humanised antibodies that target immune cells or cytokines. These as well as fusion proteins and inhibitor proteins all share varying adverse event occurrence and severity. Other approaches have included intact putative autoantigens or autoantigen peptides. Considerable logistical outlays have been deployed to develop and to translate humanised antibodies targeting immune cells, cytokines, and cytokine receptors to the clinic. Very recent phase III trials with the leading agent, a humanised anti-CD3 antibody, call into question whether further development of these biologics represents a step forward or more of the same. Combination therapies of one or more of these humanised antibodies are also being considered, and they face identical, if not more serious, impediments and safety issues. This paper will highlight the preclinical successes and the excitement generated by phase II trials while offering alternative possibilities and new translational avenues that can be explored given the very recent disappointment in leading agents in more advanced clinical trials.

  20. [Adherence of Type 2 Diabetes Mellitus approach: Current situation and possible solutions].

    Science.gov (United States)

    Orozco-Beltrán, Domingo; Mata-Cases, Manel; Artola, Sara; Conthe, Pedro; Mediavilla, Javier; Miranda, Carlos

    2016-01-01

    Define the impact and causes of non-adherent type-2 diabetes mellitus (DM2) patients, possible solutions and the role of the different health care professionals involved in the treatment. Structured questionnaire rating by a two-round Delphi method. The study was conducted in the Primary Care settings. The expert panel consisted of renowned medical professionals with extensive experience in diabetes. Assessment through a 9-point Likert scale, of the degree of agreement or disagreement on 131 items grouped into 4 blocks: impact; causes of nonadherence; diagnosis of non-adherence, and possible causes, solutions and role of the different professionals involved in adherence. The participation rate was 76.31%. The primary care health professionals agreed on 110 of the 131 proposals statements (84%), showing agreement on 102 items (77.9%) and disagreement in 8 (6.1%). Consensus was not reached on 21 items. The lack of adherence of DM2 patients makes the achievement of therapeutic control difficult. The medical practice needs to have specific training and enough resources to reduce the impact of the lack of therapeutic compliance. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

  1. Native, discount, or premium brand cigarettes: what types of cigarettes are Canadian youth currently smoking?

    Science.gov (United States)

    Elton-Marshall, Tara; Leatherdale, Scott T; Burkhalter, Robin

    2013-02-01

    The objective of the study was to determine the brand distribution of premium, discount, and native cigarette brands and to identify the factors associated with smoking these brands among a nationally representative sample of Canadian youth smokers. Data from 3,137 current smokers in Grades 9-12 participating in the 2008-2009 Youth Smoking Survey (YSS) were used to examine the prevalence and factors associated with different cigarette brand preferences. The most prevalent brand of cigarette smoked was premium cigarettes (44.7%), followed by discount cigarettes (33.7%), and to be native cigarettes (7.3%). There was significant variability in brand preference by province with the majority of youth in Atlantic Canada and Quebec smoking a discount brand of cigarettes and higher prevalence rates of native cigarette use in Ontario and Quebec. Respondents were more likely to smoke discount cigarettes if they were female, daily smokers, or if they only had $1-20 a week in spending money. Respondents were more likely to smoke native cigarettes if they were Aboriginal, heavier smokers, or if they reported having no weekly spending money. A significant proportion of students from Grade 9 to 12 in Canada smoke cigarettes that are more affordable than premium brands and it appears that the market share for these more affordable cigarette options has increased in recent years. Given that the price of cigarettes is an important determinant in youth smoking behavior, it is critical to develop and continue to enforce tobacco control strategies designed to eliminate access to cheaper sources of cigarettes among youth populations.

  2. Quantitative and qualitative differences in subcutaneous adipose tissue stores across lipodystrophy types shown by magnetic resonance imaging

    OpenAIRE

    Little Cynthia; Walcarius Rhonda; Miskie Brooke A; Robinson John F; Pollex Rebecca L; Al-Attar Salam A; Rutt Brian K; Hegele Robert A

    2007-01-01

    Abstract Background Lipodystrophies are characterized by redistributed subcutaneous fat stores. We previously quantified subcutaneous fat by magnetic resonance imaging (MRI) in the legs of two patients with familial partial lipodystrophy subtypes 2 and 3 (FPLD2 and FPLD3, respectively). We now extend the MRI analysis across the whole body of patients with different forms of lipodystrophy. Methods We studied five subcutaneous fat stores (supraclavicular, abdominal, gluteal, thigh and calf) and...

  3. Type 2 diabetes as a risk factor for cognitive impairment: current insights

    Directory of Open Access Journals (Sweden)

    Umegaki H

    2014-06-01

    Full Text Available Hiroyuki Umegaki Department of Community Healthcare and Geriatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan Abstract: Type 2 diabetes mellitus (T2DM is a risk factor for cognitive dysfunction and dementia in the elderly. T2DM has been thought to be associated with vascular diseases, eventually leading to vascular dementia, but recent studies have established that T2DM is also associated with Alzheimer’s disease (AD. With the increase in the number of elderly individuals with T2DM, the number of diabetic patients with cognitive dysfunction has been increasing. T2DM may accelerate AD-associated pathologies through insulin resistance. Vascular pathologies may also be associated with cognitive dysfunction and dementia in T2DM subjects. Several other mechanisms also seem to be involved in T2DM-related cognitive dysfunction. More investigations to clarify the association of T2DM with cognitive impairment are warranted. These investigations may help to increase our understanding of AD and open a new door to the development of therapeutics. Recent pharmaceutical advancement in T2DM treatment has resulted in the availability of a wide range of antidiabetics. Some evidence has suggested that antidiabetic therapies help to prevent cognitive dysfunction. At present, however, the optimal level of blood glucose control and the best combination of medications to achieve it in terms of cognitive preservation have not been established. More investigation is warranted. Cognitive dysfunction is an emerging new complication of T2DM that requires further study. Keywords: insulin resistance, dementia, blood glucose, amyloid ß, tau, small vascular disease

  4. Effect of Chengzai Pill on the L-Type Ca2+ Channel Currents of Osteoblasts Pretreated with Methylprednisolone

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective: To observe the effect of the serum containing Chengzai Pill on the L-type voltage-sensitive calcium channels current (L-VSCCsC) of osteoblastic MC3T3-E1 cells pretreated with methylprednisolone (mPSL). Methods: A control group, a model group, a low dose group and a high dose group were set up. The whole cell patch clamp technique was used to record L-VSCCsC of 10 osteoblastic MC3T3-E1 cells in each group and their peak currents were determined. Results: The peak current of the control group was 0.2284±0.0209 nA; the peak current of the model group was 0.1839±0.0179 nA; decreased by 19.5% as compared with the control group (P<0.01); the peak current of the low and high dose groups was 0.2526±0.0093 nA and 0.2671±0.0120 nA respectively, increased by 37.4% and 45.2% as compared with the model group (P<0.01); the difference between the low and high dose groups was P<0.05. Conclusion: 1. mPSL inhibits L-VSCCsC of osteoblasts; and 2. The serum containing Chengzai Pill increases L-VSCCsC of osteoblasts pretreated with mPSL.

  5. Current Status and Development of Nuclear Magnetic Resonance Microgyroscopes%核磁共振微陀螺的现状与发展

    Institute of Scientific and Technical Information of China (English)

    李攀; 刘元正; 王继良

    2012-01-01

    Microgyroscopes based on the nuclear magnetic resonance (NMR) become the hot research topic in the field of inertial sensors due to its small size, low power and less cost. The development history of NMR gyroscopes is reviewed and the recent international research status of NMR microgyroscopes is introduced. The theoretical base and related physical effects are introduced from three points, I. E. The nuclear magnetic resonance, optical pump and spin-exchange collision. The microgyroscopes are classified into several types according to their different structures, and the operation principles and performance parameters are reviewed, respectively. Finally, the application fields of NMR microgyroscopes are analyzed, and the development tendency and challenges impacting on practical applications are prospected. It is pointed out that the magnetic field suppressing and shielding will be the bottleneck for the practical application of NMR microgyroscopes.%基于核磁共振的微型陀螺仪以其小体积、低功耗、低成本等优势成为了惯性传感器领域新的研究热点.回顾了核磁共振陀螺仪的发展历程,并跟踪了国际上基于核磁共振的微型陀螺仪的最新研究动态.从核磁共振、光抽运和自旋交换碰撞三个方面介绍了核磁共振微陀螺的理论基础和主要涉及的物理效应.针对核磁共振微陀螺的不同结构对其进行分类,并从工作原理和性能参数等方面分别进行了阐述.最后,分析了核磁共振微陀螺的应用领域,对其发展趋势和实际应用所面临的挑战进行了展望,并指出磁抑制和磁屏蔽技术将会成为制约核磁共振微陀螺实际应用的难点.

  6. Current methods of the modeling of experimental diabetes mellitus type 2: a literature review

    Directory of Open Access Journals (Sweden)

    Yu. M. Kolesnyk

    2016-01-01

    Full Text Available Background. Diabetes mellitus (DM became a major problem of the healthcare in Ukraine. The rapid increase in the incidence was noticed especially in recent decade. The treatment of diabetes and its complications become a difficult task. From this standpoint the experimental modeling of diabetes is rather essential. Using the experimental models gives the possibility to assess the significance of the activity of pharmacological substances or to find out new mechanism in the action of medicaments. The aim of this review is to light up the most studied and common experimental models of diabetes mellitus type 2 (T2DM in small rodents and find out their drawbacks. It is known the background of T2DM is the violation of the insulin homeostasis such as the resistance of peripheral tissues to insulin as well as the dysfunction of the pancreatic beta-cells, which both lead to appearance of such phenomena as the glucosetoxicity and the lipotoxicity. In the end they both could result in life threatening vascular complications. Considering the steady growth of T2DM patients, the development both of the drug and non-drug methods of its treatment with the high therapeutically efficiency and the perfect safety profile becomes essential. The most important stage of the search of new ways of influence on pathogenetic links of T2DM is the preclinical stage. From this standpoint the usage of experimental models of T2DM has a huge importance. There are a lot of models of T2DM developed by different scientists. These models could be spontaneous or be induced by different chemical diabetogenic substances, diet or surgical interventions or be a combination of methods listed above. Conclusions. We should underline the adequate modeling of DM2T is the necessary basis for the pre-clinical study of drug-based and not-drug methods of correction of the hyperglycemic states. Using different models makes it possible for infer the obtained experimental results to the society

  7. Enhanced currents through L-type calcium channels in cardiomyocytes disturb the electrophysiology of the dystrophic heart.

    Science.gov (United States)

    Koenig, Xaver; Rubi, Lena; Obermair, Gerald J; Cervenka, Rene; Dang, Xuan B; Lukacs, Peter; Kummer, Stefan; Bittner, Reginald E; Kubista, Helmut; Todt, Hannes; Hilber, Karlheinz

    2014-02-15

    Duchenne muscular dystrophy (DMD), induced by mutations in the gene encoding for the cytoskeletal protein dystrophin, is an inherited disease characterized by progressive muscle weakness. Besides the relatively well characterized skeletal muscle degenerative processes, DMD is also associated with cardiac complications. These include cardiomyopathy development and cardiac arrhythmias. The current understanding of the pathomechanisms in the heart is very limited, but recent research indicates that dysfunctional ion channels in dystrophic cardiomyocytes play a role. The aim of the present study was to characterize abnormalities in L-type calcium channel function in adult dystrophic ventricular cardiomyocytes. By using the whole cell patch-clamp technique, the properties of currents through calcium channels in ventricular cardiomyocytes isolated from the hearts of normal and dystrophic adult mice were compared. Besides the commonly used dystrophin-deficient mdx mouse model for human DMD, we also used mdx-utr mice, which are both dystrophin- and utrophin-deficient. We found that calcium channel currents were significantly increased, and channel inactivation was reduced in dystrophic cardiomyocytes. Both effects enhance the calcium influx during an action potential (AP). Whereas the AP in dystrophic mouse cardiomyocytes was nearly normal, implementation of the enhanced dystrophic calcium conductance in a computer model of a human ventricular cardiomyocyte considerably prolonged the AP. Finally, the described dystrophic calcium channel abnormalities entailed alterations in the electrocardiograms of dystrophic mice. We conclude that gain of function in cardiac L-type calcium channels may disturb the electrophysiology of the dystrophic heart and thereby cause arrhythmias.

  8. Nitrate-nitrite-nitrosamines exposure and the risk of type 1 diabetes: A review of current data.

    Science.gov (United States)

    Bahadoran, Zahra; Ghasemi, Asghar; Mirmiran, Parvin; Azizi, Fereidoun; Hadaegh, Farzad

    2016-10-15

    The potential toxic effects of nitrate-nitrite-nitrosamine on pancreatic β cell have remained a controversial issue over the past two decades. In this study, we reviewed epidemiological studies investigated the associations between nitrate-nitrite-nitrosamines exposure, from both diet and drinking water to ascertain whether these compounds may contribute to development of type 1 diabetes. To identify relevant studies, a systematic search strategy of PubMed, Scopus, and Science Direct was conducted using queries including the key words "nitrate", "nitrite", "nitrosamine" with "type 1 diabetes" or "insulin dependent diabetes mellitus". All searches were limited to studies published in English. Ecologic surveys, case-control and cohort studies have indicated conflicting results in relation to nitrate-nitrite exposure from drinking water and the risk of type 1 diabetes. A null, sometimes even negative association has been mainly reported in regions with a mean nitrate levels water, while increased risk of type 1 diabetes was observed in those with a maximum nitrate levels > 40-80 mg/L. Limited data are available regarding the potential diabetogenic effect of nitrite from drinking water, although there is evidence indicating dietary nitrite could be a risk factor for development of type 1 diabetes, an effect however that seems to be significant in a higher range of acceptable limit for nitrate/nitrite. Current data regarding dietary exposure of nitrosamine and development of type 1 diabetes is also inconsistent. Considering to an increasing trend of type 1 diabetes mellitus (T1DM) along with an elevated nitrate-nitrite exposure, additional research is critical to clarify potential harmful effects of nitrate-nitrite-nitrosamine exposure on β-cell autoimmunity and the risk of T1DM.

  9. Design and array signal suggestion of array type pulsed eddy current probe for health monitoring of metal tubes

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Young Kil [Dept. of Electrical Engineering, Kunsan National University, Kunsan (Korea, Republic of)

    2015-10-15

    An array type probe for monitoring metal tubes is proposed in this paper which utilizes peak value and peak time of a pulsed eddy current(PEC) signal. The probe consists of an array of encircling coils along a tube and the outside of coils is shielded by ferrite to prevent source magnetic fields from directly affecting sensor signals since it is the magnetic fields produced by eddy currents that reflect the condition of metal tubes. The positions of both exciter and sensor coils are consecutively moved automatically so that manual scanning is not necessary. At one position of send-receive coils, peak value and peak time are extracted from a sensor PEC signal and these data are accumulated for all positions to form an array type peak value signal and an array type peak time signal. Numerical simulation was performed using the backward difference method in time and the finite element method for spatial analysis. Simulation results showed that peak value increases and the peak appears earlier as the defect depth or length increases. The proposed array signals are shown to be excellent in reflecting the defect location as well as variations of defect depth and length within the array probe.

  10. Single-step metal-organic vapor-phase diffusion for low-dark-current planar-type avalanche photodiodes

    Science.gov (United States)

    Jun, Dong-Hwan; Jeong, Hae Yong; Kim, Youngjo; Shin, Chan-Soo; Park, Kyung Ho; Park, Won-Kyu; Kim, Min-Su; Kim, Sangin; Han, Sang Wook; Moon, Sung

    2016-10-01

    In this paper, a p-type diffusion process based literally on single-step metal-organic vapor-phase diffusion (MOVPD) employing diethyl zinc as the diffusion source in combination with the recessetching technique is developed to improve the dark-current characteristics of planar-type avalanche photodiodes (APDs). The developed single-step MOVPD process exhibits on excellent linear relationship between the diffusion depth and the square root of the diffusion time, which mainly results from maintaining constant source diffusion. The single-step MOVPD process without any additional thermal activation process achieves a surface doping concentration of 1.9 × 1018 cm -3, which is sufficient to form ohmic contact. The measured diffusion profiles of the APDs clearly reveal the presence of a two-dimensional diffusion front formed by the recess-etched and guard-ring regions. The impact of this p-type diffusion process on the performance of the APD devices has also been demonstrated by exhibiting improved dark-current characteristics for the fabricated APDs.

  11. Dilepton events with displaced vertices, double beta decay, and resonant leptogenesis with Type-II seesaw dominance, TeV scale $Z'$ and RH neutrinos

    CERN Document Server

    Nayak, Bidyut Prava

    2015-01-01

    In a class of Type-II seesaw dominated $SO(10)$ models proposed recently with heavy neutrinos, extra $Z'$ boson, and resonant leptogenesis, at first we show that the lightest first generation sterile neutrino that mediates dominant contributions to neutrinoless double beta decay also generates the displaced vertex leading to verifiable like-sign di-electron as well as di-muon production events outside the LHC detectors having suppressed standard model back-ground and missing energy. Resonant leptogenesis in this case is implemented by a pair of quasi-degenerate sterile neutrinos of the second and the third generations having masses of ${\\cal O}(500)$ GeV. Then we predict a new alternative scenario where the models allow the second generation sterile neutrino mass to be ${\\cal O}(10)$ GeV capable of mediating the dominant double beta decay as well as the displaced vertices for significantly improved number of like-sign dilepton events in different channels. Resonant leptogenesis in this alternative scenario is...

  12. Properties of resonant states in 18Ne relevant to key 14O(alpha,p)17F breakout reaction in type I x-ray bursts

    CERN Document Server

    Hu, J; Parikh, A; Xu, S W; Yamaguchi, H; Kahl, D; Ma, P; Su, J; Wang, H W; Nakao, T; Wakabayashi, Y; Teranishi, T; Hahn, K I; Moon, J Y; Sung, H S; Hashimoto, T; Chen, A A; Irvine, D; Lee, C S; Kubono, S

    2014-01-01

    The $^{14}$O($\\alpha$,$p$)$^{17}$F reaction is one of the key reactions involved in the breakout from the hot-CNO cycle to the rp-process in type I x-ray bursts. The resonant properties in the compound nucleus $^{18}$Ne have been investigated through resonant elastic scattering of $^{17}$F+$p$. The radioactive $^{17}$F beam was separated by the CNS Radioactive Ion Beam separator (CRIB) and bombarded a thick H$_2$ gas target at 3.6 MeV/nucleon. The recoiling light particles were measured by using three ${\\Delta}$E-E silicon telescopes at laboratory angles of $\\theta$$_{lab}$$\\approx$3$^\\circ$, 10$^\\circ$ and 18$^\\circ$, respectively. Five resonances at $E_{x}$=6.15, 6.28, 6.35, 6.85, and 7.05 MeV were observed in the excitation functions. Based on an $R$-matrix analysis, $J^{\\pi}$=1$^-$ was firmly assigned to the 6.15-MeV state. This state dominates the thermonuclear $^{14}$O($\\alpha$,$p$)$^{17}$F rate below 1 GK. We have also confirmed the existence and spin-parities of three states between 6.1 and 6.4 MeV. A...

  13. Initial time-dependent current growth phenomenon in n-type organic transistors induced by interfacial dipole effects

    Science.gov (United States)

    Lin, Yi-Sheng; Yeh, Bo-Liang; Tsai, Min-Ruei; Cheng, Horng-Long; Liu, Shyh-Jiun; Tang, Fu-Ching; Chou, Wei-Yang

    2015-03-01

    We describe an unusual phenomenon of time-dependent current growth in organic transistors, particularly n-type transistors. For an organic transistor based on N,N-ditridecyl-3,4,9,10-perylene tetracarboxylic diimide with a polyimide dielectric layer, the time-dependent increase in the drain current and an approximately hysteresis-free electricity were obtained under dc-bias stress. These phenomena could be attributed to (a) reduction in the trap-state density located at the interface between polyimide and semiconductor, (b) gate field effect enhanced by electric dipoles within polyimide, and (c) a low interface trap lifetime. This study reveals that polymer dielectrics with moderate polar groups are suitable for application in stable organic devices.

  14. Fault ride-through enhancement of fixed speed wind turbine using bridge-type fault current limiter

    Directory of Open Access Journals (Sweden)

    Mostafa I. Marei

    2016-05-01

    Full Text Available The interaction between wind energy turbines and the grid results in two main problems, increasing the short-circuit level and reducing the Fault Ride-Through (FRT capability during faults. The objective of this paper is to solve these problems, for fixed speed Wind Energy Systems (WECS, utilizing the bridge-type Fault Current Limiter (FCL with a discharging resistor. A simple cascaded control system is proposed for the FCL to regulate the terminal voltage of the generator and limit the current. The system is simulated on PSCAD/EMTDC software to evaluate the dynamic performance of the proposed WECS compensated by FCL. The simulation results show the potentials of the FCL as a simple and effective method for solving grid interconnection problems of WECS.

  15. Gain and Threshold Current in Type II In(AsSb Mid-Infrared Quantum Dot Lasers

    Directory of Open Access Journals (Sweden)

    Qi Lu

    2015-04-01

    Full Text Available In this work, we improved the performance of mid-infrared type II InSb/InAs quantum dot (QD laser diodes by incorporating a lattice-matched p-InAsSbP cladding layer. The resulting devices exhibited emission around 3.1 µm and operated up to 120 K in pulsed mode, which is the highest working temperature for this type of QD laser. The modal gain was estimated to be 2.9 cm−1 per QD layer. A large blue shift (~150 nm was observed in the spontaneous emission spectrum below threshold due to charging effects. Because of the QD size distribution, only a small fraction of QDs achieve threshold at the same injection level at 4 K. Carrier leakage from the waveguide into the cladding layers was found to be the main reason for the high threshold current at higher temperatures.

  16. Influences of Resistor-Type Superconducting Fault Current Limiter on Power System Transient Stability with Asymmetrical Short-Circuit Faults

    Institute of Scientific and Technical Information of China (English)

    Xue-Ping Gu; Zhi-Long Yang

    2008-01-01

    The transient stability of a single machine to infinite-busbar power system with resistor- type superconducting fault current limiters (SFCL) is analyzed under asymmetrical short-circuit fault conditions. The SFCL is considered to introduce a resistance into the three-phase circuits when faults occur. Based on the power-angle curves for different short-circuit conditions of the single-line to ground, double-line to ground and line to line short-circuit faults, the influences of the SFCLs on transient stability are analyzed in detail. The time-domain simulation of transient stability is carried out to verify the analytical results.

  17. Nitrate-nitrite-nitrosamines exposure and the risk of type 1 diabetes: A review of current data

    Science.gov (United States)

    Bahadoran, Zahra; Ghasemi, Asghar; Mirmiran, Parvin; Azizi, Fereidoun; Hadaegh, Farzad

    2016-01-01

    The potential toxic effects of nitrate-nitrite-nitrosamine on pancreatic β cell have remained a controversial issue over the past two decades. In this study, we reviewed epidemiological studies investigated the associations between nitrate-nitrite-nitrosamines exposure, from both diet and drinking water to ascertain whether these compounds may contribute to development of type 1 diabetes. To identify relevant studies, a systematic search strategy of PubMed, Scopus, and Science Direct was conducted using queries including the key words “nitrate”, “nitrite”, “nitrosamine” with “type 1 diabetes” or “insulin dependent diabetes mellitus”. All searches were limited to studies published in English. Ecologic surveys, case-control and cohort studies have indicated conflicting results in relation to nitrate-nitrite exposure from drinking water and the risk of type 1 diabetes. A null, sometimes even negative association has been mainly reported in regions with a mean nitrate levels 40-80 mg/L. Limited data are available regarding the potential diabetogenic effect of nitrite from drinking water, although there is evidence indicating dietary nitrite could be a risk factor for development of type 1 diabetes, an effect however that seems to be significant in a higher range of acceptable limit for nitrate/nitrite. Current data regarding dietary exposure of nitrosamine and development of type 1 diabetes is also inconsistent. Considering to an increasing trend of type 1 diabetes mellitus (T1DM) along with an elevated nitrate-nitrite exposure, additional research is critical to clarify potential harmful effects of nitrate-nitrite-nitrosamine exposure on β-cell autoimmunity and the risk of T1DM. PMID:27795817

  18. Magnetic resonance imaging for Human T-cell lymphotropic virus type 1 (HTLV1- associated myelopathy/tropical spastic paraparesis patients: a systematic review

    Directory of Open Access Journals (Sweden)

    Fariba Zemorshidi

    2015-06-01

    Full Text Available Introduction: Human T-cell lymphotropic virus type 1 (HTLV-1 associated myelopathy/tropical spastic paraparesis is a chronic progressive neurologic disease which might be associated by brain and spinal cord atrophy and lesions. Here we systematically reviewed the brain and spinal cord abnormalities reported by using magnetic resonance imaging modality on HTLV-1 associated myelopathy/tropical spastic paraparesis patients. Methods: PubMed was searched for all the relevant articles which used magnetic resonance imaging for patients with human HTLV-1 associated myelopathy/tropical spastic paraparesis disease. Included criteria were all the cohort and case series on with at least 10 patients. We had no time limitation for searched articles, but only English language articles were included in our systematic review. Exclusion criteria were none-English articles, case reports, articles with less than 10 patients, spastic paraparesis patients with unknown etiology, and patients with HTLVII. Results: Total of 14 relevant articles were extracted after studying title, abstracts, and full text of the irrelevant articles. Only 2/14 articles, reported brain atrophy incidence. 5/14 articles studied the brain lesions prevalence. Spinal cord atrophy and lesions, each were studied in 6/14 articles.Discussion: According to the extracted data, brain atrophy does not seem to happen frequently in patients with HTLV-1 associated myelopathy/tropical spastic paraparesis. None-specific brain lesions identified in articles are indicative of low specificity of magnetic resonance imaging technique despite its high sensitivity. Conclusion: Prevalence of spinal cord lesions and atrophy in these patients might be due to the degenerative processes associated with aging phenomenon. Further larger studies in endemic areas can more accurately reveal the specificity of magnetic resonance imaging for these patients.

  19. Effect of resonance frequency, power input, and saturation gas type on the oxidation efficiency of an ultrasound horn.

    Science.gov (United States)

    Rooze, Joost; Rebrov, Evgeny V; Schouten, Jaap C; Keurentjes, Jos T F

    2011-01-01

    The sonochemical oxidation efficiency (η(ox)) of a commercial titanium alloy ultrasound horn has been measured using potassium iodide as a dosimeter at its main resonance frequency (20 kHz) and two higher resonance frequencies (41 and 62 kHz). Narrow power and frequency ranges have been chosen to minimise secondary effects such as changing bubble stability, and time available for radical diffusion from the bubble to the liquid. The oxidation efficiency, η(ox), is proportional to the frequency and to the power transmitted to the liquid (275 mL) in the applied power range (1-6 W) under argon. Luminol radical visualisation measurements show that the radical generation rate increases and a redistribution of radical producing zones is achieved at increasing frequency. Argon, helium, air, nitrogen, oxygen, and carbon dioxide have been used as saturation gases in potassium iodide oxidation experiments. The highest η(ox) has been observed at 5 W under air at 62 kHz. The presence of carbon dioxide in air gives enhanced nucleation at 41 and 62 kHz and has a strong influence on η(ox). This is supported by the luminol images, the measured dependence of η(ox) on input power, and bubble images recorded under carbon dioxide. The results give insight into the interplay between saturation gas and frequency, nucleation, and their effect on η(ox).

  20. A fast BK-type KCa current acts as a postsynaptic modulator of temporal selectivity for communication signals

    Directory of Open Access Journals (Sweden)

    Tsunehiko eKohashi

    2014-09-01

    Full Text Available Temporal patterns of spiking often convey behaviorally relevant information. Various synaptic mechanisms and intrinsic membrane properties can influence neuronal selectivity to temporal patterns of input. However, little is known about how synaptic mechanisms and intrinsic properties together determine the temporal selectivity of neuronal output. We tackled this question by recording from midbrain electrosensory neurons in mormyrid fish, in which the processing of temporal intervals between communication signals can be studied in a reduced in vitro preparation. Mormyrids communicate by varying interpulse intervals (IPIs between electric pulses. Within the midbrain posterior exterolateral nucleus (ELp, the temporal patterns of afferent spike trains are filtered to establish single-neuron IPI tuning. We performed whole-cell recording from ELp neurons in a whole-brain preparation and examined the relationship between intrinsic excitability and IPI tuning. We found that spike frequency adaptation of ELp neurons was highly variable. Postsynaptic potentials (PSPs of strongly adapting (phasic neurons were more sharply tuned to IPIs than weakly adapting (tonic neurons. Further, the synaptic filtering of IPIs by tonic neurons was more faithfully converted into variation in spiking output, particularly at short IPIs. Pharmacological manipulation under current- and voltage-clamp revealed that tonic firing is mediated by a fast, large-conductance Ca2+-activated K+ (KCa current (BK that speeds up action potential repolarization. These results suggest that BK currents can shape the temporal filtering of sensory inputs by modifying both synaptic responses and PSP-to-spike conversion. Slow SK-type KCa currents have previously been implicated in temporal processing. Thus, both fast and slow KCa currents can fine-tune temporal selectivity.

  1. Resonance characteristic and its ionic basis of rat mesencephalic trigeminal neurons.

    Science.gov (United States)

    Yang, Jing; Hu, Sanjue; Li, Fujun; Xing, Junling

    2015-01-30

    Intrinsic resonant frequency properties of neurons in the brain provide a basis for different behavioral states and determine the responding modality (i.e. excitability) of different neurons. Previously, three types of excitability behaviors in rat Mesencephalic V neurons were found. To investigate the different resonant frequency and ionic current mechanisms underlying different resonances among three types of excitability, we performed whole-cell patch recordings and applied ZAP current on Mesencephalic V cells (N=70) in rat slices. The results show that: Class 2 neurons (30/30) have two resonances with U-shaped voltage dependence. One is a high frequency resonance (75.4 ± 2.11 Hz) significant at depolarized potentials (about -50 mV) and the other is a low frequency resonance (5.46 ± 0.31 Hz) significant at hyperpolarized potentials (about -70 mV). Voltage clamp experiments reveal two non-inactivating currents operating in the subthreshold voltage range: (1) 4-aminopyridine sensitive K(+) current, which activates at membrane potentials positive than -60 mV and was blocked by 4-AP (50 µM), was underlying the high frequency resonance of Class 2 neuron; (2) h-current, which activates negative than -60mV and was blocked by the hyperpolarization-activated cyclic nucleotide-gated channel blocker ZD7288 (10 µM), was underlying the low frequency resonance. Class 1 neurons do not show voltage-dependence resonant behaviors (10/10). Class 3 neurons (23/30) have two resonances, which are similar with Class 2 in both resonant frequency and currents. Our results provide clear evidence for the existence of multiple kinds of frequency resonances and how the relationship between the resonant frequency and the ionic current is based in Mesencephalic V neurons.

  2. Subclinical coronary and aortic atherosclerosis detected by magnetic resonance imaging in type 1 diabetes with and without diabetic nephropathy

    DEFF Research Database (Denmark)

    Kim, Won Yong; Astrup, Anne Sofie; Stuber, Matthias

    2007-01-01

    BACKGROUND: Patients with type 1 diabetes and nephropathy maintain an excess cardiovascular mortality compared with diabetic patients with normoalbuminuria. We sought to evaluate coronary and aortic atherosclerosis in a cohort of asymptomatic type 1 diabetic patients with and without diabetic nep...

  3. Application of a modified flux-coupling type superconducting fault current limiter to transient performance enhancement of micro-grid

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lei, E-mail: stclchen1982@163.com [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Zheng, Feng; Deng, Changhong; Li, Shichun; Li, Miao; Liu, Hui [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Zhu, Lin [Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville 37996 (United States); Guo, Fang [Department of Substation, Guang Dong Electric Power Design Institute, Guangzhou 510663 (China)

    2015-11-15

    Highlights: • A modified flux-coupling type SFCL is suggested to enhance the transient performance of a micro-grid. • The SFCL’s main contribution is to improve the micro-grid’s fault ride-through capability. • The SFCL also can make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. • The simulations show that the SFCL can availably strengthen the micro-grid’s voltage and frequency stability. - Abstract: Concerning the application and development of a micro-grid system which is designed to accommodate high penetration of intermittent renewable resources, one of the main issues is related to an increase in the fault-current level. It is crucial to ensure the micro-grid’s operational stability and service reliability when a fault occurs in the main network. In this paper, our research group suggests a modified flux-coupling type superconducting fault current limiter (SFCL) to enhance the transient performance of a typical micro-grid system. The SFCL is installed at the point of common coupling (PCC) between the main network and the micro-grid, and it is expected to actively improve the micro-grid’s fault ride-through capability. And for some specific faults, the micro-grid should disconnect from the main network, and the SFCL’s contribution is to make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. Related theory derivation, technical discussion and simulation analysis are performed. From the demonstrated results, applying the SFCL can effectively limit the fault current, maintain the power balance, and enhance the voltage and frequency stability of the micro-grid.

  4. Application of a modified flux-coupling type superconducting fault current limiter to transient performance enhancement of micro-grid

    Science.gov (United States)

    Chen, Lei; Zheng, Feng; Deng, Changhong; Li, Shichun; Li, Miao; Liu, Hui; Zhu, Lin; Guo, Fang

    2015-11-01

    Concerning the application and development of a micro-grid system which is designed to accommodate high penetration of intermittent renewable resources, one of the main issues is related to an increase in the fault-current level. It is crucial to ensure the micro-grid's operational stability and service reliability when a fault occurs in the main network. In this paper, our research group suggests a modified flux-coupling type superconducting fault current limiter (SFCL) to enhance the transient performance of a typical micro-grid system. The SFCL is installed at the point of common coupling (PCC) between the main network and the micro-grid, and it is expected to actively improve the micro-grid's fault ride-through capability. And for some specific faults, the micro-grid should disconnect from the main network, and the SFCL's contribution is to make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. Related theory derivation, technical discussion and simulation analysis are performed. From the demonstrated results, applying the SFCL can effectively limit the fault current, maintain the power balance, and enhance the voltage and frequency stability of the micro-grid.

  5. Frequency-temperature sensitivity reduction with optimized microwave Bragg resonators

    Science.gov (United States)

    Le Floch, J.-M.; Murphy, C.; Hartnett, J. G.; Madrangeas, V.; Krupka, J.; Cros, D.; Tobar, M. E.

    2017-01-01

    Dielectric resonators are employed to build state-of-the-art low-noise and high-stability oscillators operating at room and cryogenic temperatures. A resonator temperature coefficient of frequency is one criterion of performance. This paper reports on predictions and measurements of this temperature coefficient of frequency for three types of cylindrically symmetric Bragg resonators operated at microwave frequencies. At room temperature, microwave Bragg resonators have the best potential to reach extremely high Q-factors. Research has been conducted over the last decade on modeling, optimizing, and realizing such high Q-factor devices for applications such as filtering, sensing, and frequency metrology. We present an optimized design, which has a temperature sensitivity 2 to 4 times less than current whispering gallery mode resonators without using temperature compensating techniques and about 30% less than other existing Bragg resonators. Also, the performance of a new generation single-layered Bragg resonator, based on a hybrid-Bragg-mode, is reported with a sensitivity of about -12 ppm/K at 295 K. For a single reflector resonator, it achieves a similar level of performance as a double-Bragg-reflector resonator but with a more compact structure and performs six times better than whispering-gallery-mode resonators. The hybrid resonator promises to deliver a new generation of high-sensitivity sensors and high-stability room-temperature oscillators.

  6. Study of recovery characteristics of 2nd generation HTS tapes with different stabilizers for resistive type superconducting fault current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Jie, E-mail: 1988725sheng@163.com; Zeng, Weina; Ma, Jun; Yao, Zhihao; Li, Zhuyong; Jin, Zhijian; Hong, Zhiyong

    2016-02-15

    Highlights: • Three methods of measuring the recovery time of HTS tapes are compared. • Four tapes with different stabilizers were tested to compare their recovery characteristics. • The HTS tapes with thinner stabilizers have better recovery characteristics. • Encapsulation makes the recovery characteristics of HTS tapes worse. • The results can be reference of the re-reclosed operation time interval. - Abstract: The resistive type superconducting fault current limiter (SFCL) is one of the most important superconducting power applications nowadays. As known, this type of SFCL is settled directly in the power transmission line. When a short fault happens, the temperature of the superconductors in the SFCL will increase sharply due to the huge generated heat. This means the superconductors need time to recover the superconducting properties and be ready for the next short fault. So the recovery characteristics become one of the most crucial features of the resistive type SFCL. In this paper, several different kinds of measuring methods are presented to calculate the recovery time of the HTS tapes, and comparison of these methods is also carried out by a standard test. On basis of this, samples with different kinds of stabilizers are used to explore the influence of stabilizer on their recovery characteristics. In addition, the influence of the encapsulation technology is also discussed in this paper.

  7. Studies on the Performance of Different Coiled Column Configurations for Compact Type-I Counter-current Chromatography

    Science.gov (United States)

    Yang, Yi; Gu, Dongyu; Aisa, Haji Akber; Ito, Yoichiro

    2011-01-01

    Three types of novel coiled column configurations, i.e., a triangular coiled column and elliptical coiled columns I and II, were designed for type-I countercurrent chromatography and their performances were evaluated with two solvent systems each with suitable test samples. Three DNP-amino acids (DNP-DL-glu, DNP-β-ala and DNP-L-ala) were separated with a moderately hydrophobic two-phase solvent system composed of hexane-ethyl acetate-metanol-0.1M hydrochloric acid (1:1:1:1, v/v), while two dipeptides (tryptophyl tyrosine and valyl-tyrosine) were separated with a polar solvent system composed of 1-butanol-acetic acid-water (4.75:0.25:5, v/v). The overall results indicated that the performance of compact type-I counter-current chromatography was improved by elliptical coiled column II which was mounted with its maximum coil diameter perpendicular to the surface of the column holder. Hydrodynamic effects involved in these separations were discussed. PMID:21491597

  8. Research on magnetic integrated for zero-current quasi-resonant buck converter%零电流准谐振Buck变换器的磁集成研究

    Institute of Scientific and Technical Information of China (English)

    陈正一; 杨玉岗; 李洪珠

    2011-01-01

    Taking Buck converter as an example,the resonant inductor and resonant capacitor were introduced, which constituted the resonant switch with the converter power switch. Through the resonance,the waveform of current through the power switch became sinusoidal,which created zero-current switching condition for power switch. In this paper, the discrete resonant inductor and filter inductor were integrated to integration magnetic, and the principle of integration Buck converter works was described. The integration of circuit was simulated by Saber software, and the effect of coupling coefficient of the resonant inductor and filter inductor on the resonant frequency and output voltage was analyzed. The loosely coupled and tightly coupled integration approach Was applied to design a ZCS Buck converter,and the zero-current turn-on and zero-current turn-off of power switch was achieved, and was authenticated by saber.%以零电流准谐振Buck变换器为例,引入谐振电感和谐振电容与变换器中的功率开关管组成谐振开关.通过谐振,使流过功率开关管的电流呈正弦波形,为功率开关管创造了零电流开关条件.对分立的谐振电感和滤波电感进行磁集成,阐述集成后Buck变换器工作原理.用Saber软件对集成后的电路进行仿真.分析谐振电感和滤波电感的耦合系数对谐振频率和输出电压的影响.最后采用松耦合和紧耦合两种集成方法设计了一台零电流准谐振Buck变换器,通过Saber软件仿真验证功率开关管实现了零电流开通和零电流关断.

  9. Magneto-optical study of the intermediate state in type-I superconductors: Effects of sample shape and applied current

    Energy Technology Data Exchange (ETDEWEB)

    Hoberg, Jacob Ray [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    The magnetic flux structures in the intermediate state of bulk, pinning-free Type-I superconductors are studied using a high resolution magneto-optical imaging technique. Unlike most previous studies, this work focuses on the pattern formation of the coexisting normal and superconducting phases in the intermediate state. The influence of various parameters such as sample shape, structure defects (pinning) and applied current are discussed in relation to two distinct topologies: flux tubes (closed topology) and laminar (open topology). Imaging and magnetization measurements performed on samples of different shapes (cones, hemispheres and slabs), show that contrary to previous beliefs, the tubular structure is the equilibrium topology, but it is unstable toward defects and flux motion. Moreover, the application of current into a sample with the geometric barrier can replace an established laminar structure with flux tubes. At very high currents, however, there exists a laminar 'stripe pattern.' Quantitative analysis of the mean tube diameter is shown to be in good agreement with the prediction proposed by Goren and Tinkham. This is the first time that this model has been confirmed experimentally. Further research into the flux tube phase shows a direct correlation with the current loop model proposed in the 1990's by Goldstein, Jackson and Dorsey. There also appears a range of flux tube density that results in a suprafroth structure, a well-formed polygonal mesh, which behaves according to the physics of foams, following standard statistical laws such as von Neumann and Lewis. The reaction of flux structures to a fast-ramped magnetic field was also studied. This provided an alignment of the structure not normally observed at slow ramp rates.

  10. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... type your comment or suggestion into the following text box: Comment: E-mail: Area code: Phone no: ... Resonance, Functional (fMRI) - Brain Head and Neck Cancer Treatment Brain Tumor Treatment Magnetic Resonance Imaging ( ...

  11. Dynamically generated resonances

    CERN Document Server

    Oset, E; Sarkar, S; Sun, Bao Xi; Vacas, M J Vicente; González, P; Vijande, J; Jido, D; Sekihara, T; Torres, A Martinez; Khemchandani, K

    2009-01-01

    In this talk I report on recent work related to the dynamical generation of baryonic resonances, some made up from pseudoscalar meson-baryon, others from vector meson-baryon and a third type from two meson-one baryon systems. We can establish a correspondence with known baryonic resonances, reinforcing conclusions previously drawn and bringing new light on the nature of some baryonic resonances of higher mass.

  12. Mechanism for Muscarinic Inhibitory Regulation of the L-type Ca2 + Current in Cardiac Ventricular Myocytes

    Institute of Scientific and Technical Information of China (English)

    蒋彬; 杨向军; 惠杰; 蒋廷波; 宋建平; 刘志华

    2004-01-01

    @@ Objective The autonomic nervous system plays a key role in regulating cardiac function by modifying heart rate, contractility and impulse. The parasympathetic neurotransmitter acetyl-choline and muscarinic agonist carbachol (Cch) inhibit excitation-contraction coupling in cardiac ventricular myocytes. Muscarinic agonists suppress adenylyl cyclase (AC) acitivity and,by reducing activation of the cAMP/protein kinase A (PKA)cascade, inhibit the L-type Ca2+ current (ICa(L) ). They also increase the content of cGMP by stimulating guanylyl cyclase (GC) activity. The role of nitric oxide (NO)/cGMP in muscarinic inhibition has undergone considerable scrutiny. The role of the NO/cGMP pathway in the inhibition of ICa(L) by Cch was examined in guinea-pig ventricular myocytes.

  13. Intrinsic Differences in Backbone Dynamics between Wild Type and DNA-Contact Mutants of the p53 DNA Binding Domain Revealed by Nuclear Magnetic Resonance Spectroscopy.

    Science.gov (United States)

    Rasquinha, Juhi A; Bej, Aritra; Dutta, Shraboni; Mukherjee, Sujoy

    2017-09-07

    Mutations in p53's DNA binding domain (p53DBD) are associated with 50% of all cancers, making it an essential system to investigate and understand the genesis and progression of cancer. In this work, we studied the changes in the structure and dynamics of wild type p53DBD in comparison with two of its "hot-spot" DNA-contact mutants, R248Q and R273H, by analysis of backbone amide chemical shift perturbations and (15)N spin relaxation measurements. The results of amide chemical shift changes indicated significantly more perturbations in the R273H mutant than in wild type and R248Q p53DBD. Analysis of (15)N spin relaxation rates and the resulting nuclear magnetic resonance order parameters suggests that for most parts, the R248Q mutant exhibits limited conformational flexibility and is similar to the wild type protein. In contrast, R273H showed significant backbone dynamics extending up to its β-sandwich scaffold in addition to motions along the DNA binding interface. Furthermore, comparison of rotational correlation times between the mutants suggests that the R273H mutant, with a higher correlation time, forms an enlarged structural fold in comparison to the R248Q mutant and wild type p53DBD. Finally, we identify three regions in these proteins that show conformational flexibility to varying degrees, which suggests that the R273H mutant, in addition to being a DNA-contact mutation, exhibits properties of a conformational mutant.

  14. Abnormal sodium current properties contribute to cardiac electrical and contractile dysfunction in a mouse model of myotonic dystrophy type 1.

    Science.gov (United States)

    Algalarrondo, Vincent; Wahbi, Karim; Sebag, Frédéric; Gourdon, Geneviève; Beldjord, Chérif; Azibi, Kamel; Balse, Elise; Coulombe, Alain; Fischmeister, Rodolphe; Eymard, Bruno; Duboc, Denis; Hatem, Stéphane N

    2015-04-01

    Myotonic dystrophy type 1 (DM1) is the most common neuromuscular disorder and is associated with cardiac conduction defects. However, the mechanisms of cardiac arrhythmias in DM1 are unknown. We tested the hypothesis that abnormalities in the cardiac sodium current (INa) are involved, and used a transgenic mouse model reproducing the expression of triplet expansion observed in DM1 (DMSXL mouse). The injection of the class-I antiarrhythmic agent flecainide induced prominent conduction abnormalities and significantly lowered the radial tissular velocities and strain rate in DMSXL mice compared to WT. These abnormalities were more pronounced in 8-month-old mice than in 3-month-old mice. Ventricular action potentials recorded by standard glass microelectrode technique exhibited a lower maximum upstroke velocity [dV/dt](max) in DMSXL. This decreased [dV/dt](max) was associated with a 1.7 fold faster inactivation of INa in DMSXL myocytes measured by the whole-cell patch-clamp technique. Finally in the DMSXL mouse, no mutation in the Scn5a gene was detected and neither cardiac fibrosis nor abnormalities of expression of the sodium channel protein were observed. Therefore, alterations in the sodium current markedly contributed to electrical conduction block in DM1. This result should guide pharmaceutical and clinical research toward better therapy for the cardiac arrhythmias associated with DM1.

  15. Multi-scale model of resistive-type superconducting fault current limiters based on 2G HTS coated conductors

    Science.gov (United States)

    Bonnard, Charles-Henri; Sirois, Frédéric; Lacroix, Christian; Didier, Gaëtan

    2017-01-01

    In order to plan the integration of superconducting fault current limiters (SFCLs) in power systems, accurate models of SFCLs must be made available in commercial power system transient simulators. In this context, we developed such a model for the EMTP-RV software package, a power system transient simulator widely used by power utilities. The model can be used with any resistive-type SFCL (rSFCL) made of high temperature superconductor (HTS) tapes, which are discretized in ‘electro-thermal elements’. Those elements consist solely of electric circuit components, and are used to represent portions of tape of various sizes and dimensions (a ‘multi-scale’ approach). Both the electrical and thermal behaviors of the tape are modeled, including interfacial effects, nonlinear properties of materials and heat transfer to the surrounding environment. Such a multi-scale model can simulate accurately both the local quench dynamics of HTS tapes (microscopic scale) and the global impact of the rSFCL on the power system (macroscopic/system scale). In this paper, the model is used to compute phenomena such as propagation velocity of a hot spot and heat diffusion through the thickness of the tape. Results were verified by comparing EMTP-RV results with finite element simulations. In addition to the development of the multi-scale model itself, which is the major contribution of this paper, the use of the model allowed us to determine the conditions of validity of the commonly used ‘homogenization’ of the thermal properties across the tape thickness. Indeed, when the current flowing into the rSFCL is slightly above its critical current I c (and up to 2{I}{{c}}), very important errors in the power waveforms arise, leading to potentially wrong decisions of protection systems. Homogenized thermal models should thus be used with great care in practice.

  16. Enhanced effect of VEGF165 on L-type calcium currents in guinea-pig cardiac ventricular myocytes.

    Science.gov (United States)

    Xing, Wenlu; Gao, Chuanyu; Qi, Datun; Zhang, You; Hao, Peiyuan; Dai, Guoyou; Yan, Ganxin

    2017-01-01

    The mechanisms of vascular endothelial growth factor 165 (VEGF165) on electrical properties of cardiomyocytes have not been fully elucidated. The aim of this study is to test the hypothesis that VEGF165, an angiogenesis-initiating factor, affects L-type calcium currents (ICa,L) and cell membrane potential in cardiac myocytes by acting on VEGF type-2 receptors (VEGFR2). ICa,L and action potentials (AP) were recorded by the whole-cell patch clamp method in isolated guinea-pig ventricular myocytes treated with different concentrations of VEGF165 proteins. Using a VEGFR2 inhibitor, we also tested the receptor of VEGF165 in cardiomyocytes. We found that VEGF165 increased ICa,L in a concentration-dependent manner. SU5416, a VEGFR2 inhibitor, almost completely eliminated VEGF165-induced ICa,L increase. VEGF165 had no significant influence on action potential 90 (APD90) and other properties of AP. We conclude that in guinea-pig ventricular myocytes, ICa,L can be increased by VEGF165 in a concentration-dependent manner through binding to VEGFR2 without causing any significant alteration to action potential duration. Results of this study may further expound the safety of VEGF165 when used in the intervention of heart diseases.

  17. Capacitor Current Feedback-Based Active Resonance Damping Strategies for Digitally-Controlled Inductive-Capacitive-Inductive-Filtered Grid-Connected Inverters

    DEFF Research Database (Denmark)

    Lorzadeh, Iman; Askarian Abyaneh, Hossein; Savaghebi, Mehdi

    2016-01-01

    attracted considerable attention due to its effective damping performance and simple implementation. This paper thus presents a state-of-the-art review of resonance and stability characteristics of CCF-based AD approaches for a digitally-controlled LCL filter-based grid-connected inverter taking...

  18. Magnetic resonance energy and topological resonance energy.

    Science.gov (United States)

    Aihara, Jun-Ichi

    2016-04-28

    Ring-current diamagnetism of a polycyclic π-system is closely associated with thermodynamic stability due to the individual circuits. Magnetic resonance energy (MRE), derived from the ring-current diamagnetic susceptibility, was explored in conjunction with graph-theoretically defined topological resonance energy (TRE). For many aromatic molecules, MRE is highly correlative with TRE with a correlation coefficient of 0.996. For all π-systems studied, MRE has the same sign as TRE. The only trouble with MRE may be that some antiaromatic and non-alternant species exhibit unusually large MRE-to-TRE ratios. This kind of difficulty can in principle be overcome by prior geometry-optimisation or by changing spin multiplicity. Apart from the semi-empirical resonance-theory resonance energy, MRE is considered as the first aromatic stabilisation energy (ASE) defined without referring to any hypothetical polyene reference.

  19. Resonance frequency analysis

    Directory of Open Access Journals (Sweden)

    Rajiv K Gupta

    2011-01-01

    Full Text Available Initial stability at the placement and development of osseointegration are two major issues for implant survival. Implant stability is a mechanical phenomenon which is related to the local bone quality and quantity, type of implant, and placement technique used. The application of a simple, clinically applicable, non-invasive test to assess implant stability and osseointegration is considered highly desirable. Resonance frequency analysis (RFA is one of such techniques which is most frequently used now days. The aim of this paper was to review and analyze critically the current available literature in the field of RFA, and to also discuss based on scientific evidence, the prognostic value of RFA to detect implants at risk of failure. A search was made using the PubMed database to find all the literature published on "Resonance frequency analysis for implant stability" till date. Articles discussed in vivo or in vitro studies comparing RFA with other methods of implant stability measurement and articles discussing its reliability were thoroughly reviewed and discussed. A limited number of clinical reports were found. Various studies have demonstrated the feasibility and predictability of the technique. However, most of these articles are based on retrospective data or uncontrolled cases. Randomized, prospective, parallel-armed longitudinal human trials are based on short-term results and long-term follow up are still scarce in this field. Nonetheless, from available literature, it may be concluded that RFA technique evaluates implant stability as a function of stiffness of the implant bone interface and is influenced by factors such as bone type, exposed implant height above the alveolar crest. Resonance frequency analysis could serve as a non-invasive diagnostic tool for detecting the implant stability of dental implants during the healing stages and in subsequent routine follow up care after treatment. Future studies, preferably randomized

  20. A Landesman-Lazer Type Theorem for Periodic Solutions of the Resonant Asymmetric p-Laplacian Equation

    Institute of Scientific and Technical Information of China (English)

    Mei Yue JIANG

    2005-01-01

    In this paper, we give a Landesman-Lazer type theorem for periodic solutions of the asymmetric 1-dimensional p-Laplacian equation-(|x'|p-2x')' =λ|x|p-2x+ + μ|x|p-2x_ + f(t, x)with periodic boundary value.

  1. Cardiac effects of 3 months treatment of acromegaly evaluated by magnetic resonance imaging and B-type natriuretic peptides

    DEFF Research Database (Denmark)

    Andreassen, Mikkel; Faber, Jens Oscar; Kjær, Andreas;

    2010-01-01

    Long-term treatment of acromegaly prevents aggravation and reverses associated heart disease. A previous study has shown a temporary increase in serum levels of the N-terminal fraction of pro B-type natriuretic peptide (NT-proBNP) suggesting an initial decline in cardiac function when treatment...

  2. Nonlinear Goos-Haenchen shifts due to surface polariton resonance in Kretschmann configuration with a Kerr-type substrate

    Energy Technology Data Exchange (ETDEWEB)

    Xu Guoding, E-mail: guodingxu@163.co [Department of Physics, Suzhou University of Science and Technology, Suzhou 215009 (China); Zang Taocheng; Mao Hongmin; Pan Tao [Department of Physics, Suzhou University of Science and Technology, Suzhou 215009 (China)

    2010-07-26

    As the surface polaritons are excited in Kretschmann configuration with a Kerr-type substrate, the nonlinear Goos-Haenchen (GH) shifts exhibit the optically hysteretic response to the intensity of incident light. For thicker metal films, the GH shifts become very sensitive to the intensity of incident light and the angle of incidence.

  3. Magnetic resonance imaging in a juvenile type of distal and segmental muscular atrophy of the upper extremities

    Energy Technology Data Exchange (ETDEWEB)

    Hasuo, K. [Dept. of Radiology, Faculty of Medicine, Kyushu Univ., Fukuoka (Japan); Uchino, A. [Dept. of Radiology, Faculty of Medicine, Kyushu Univ., Fukuoka (Japan); Matsumoto, S. [Dept. of Radiology, Faculty of Medicine, Kyushu Univ., Fukuoka (Japan); Yoshida, K. [Dept. of Radiology, Faculty of Medicine, Kyushu Univ., Fukuoka (Japan); Kira, J. [Dept. of Neurology, Faculty of Medicine, Kyushu Univ., Fukuoka (Japan); Masuda, K. [Dept. of Radiology, Faculty of Medicine, Kyushu Univ., Fukuoka (Japan)

    1994-04-01

    Eight patients with a juvenile type of distal and segmental muscular atrophy of the upper extremities (DSMA), a type of cervical flexion myelopathy, were evaluated using MR imaging. In the neutral position there was no spinal cord compression, but in flexion the spinal cord was displaced anteriorly and was compressed by the posterior surfaces or margins of the vertebrae and/or any herniated disks in all cases. In flexion, compression of the cord was exaggerated in seven patients by the anterior displacement of the posterior margin of the thecal sac, which was accompanied by dilated posterior internal vertebral veins. In patients suspected of having DSMA, MR images made in flexion are regarded essential for verifying the diagnosis. (orig.)

  4. Nonclasssical Properties in Two-Mode Fields Resonantly Interacting with a Three-Level [Ⅰ]-Type Atom

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Some noclassical properties in electromagnetic Reid are investigated for the interaction of two-modes initially taken in coherent-state representation with the three-level [Ⅰ]-type atom, such as squeezing properties and violation of the Cauchy-Schwartz inequality. The enhancement of Geld squeezing is found by selective atomic measurement. The Cauchy-Schwartz inequality is violated by the application of the classical Geld followed by detection in excited state.

  5. Aortic stiffness is associated with cardiac function and cerebral small vessel disease in patients with type 1 diabetes mellitus: assessment by magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Elderen, Saskia G.C. van; Brandts, A.; Westenberg, J.J.M.; Grond, J. van der; Buchem, M.A. van; Kroft, L.J.M.; Roos, A. de [Leiden University Medical Center, Department of Radiology, Leiden (Netherlands); Tamsma, J.T.; Romijn, J.A.; Smit, J.W.A. [Leiden University Medical Center, Department of Endocrinology, Leiden (Netherlands)

    2010-05-15

    To evaluate, with the use of magnetic resonance imaging (MRI), whether aortic pulse wave velocity (PWV) is associated with cardiac left ventricular (LV) function and mass as well as with cerebral small vessel disease in patients with type 1 diabetes mellitus (DM). We included 86 consecutive type 1 DM patients (49 male, mean age 46.9 {+-} 11.7 years) in a prospective, cross-sectional study. Exclusion criteria included aortic/heart disease and general MRI contra-indications. MRI of the aorta, heart and brain was performed for assessment of aortic PWV, as a marker of aortic stiffness, systolic LV function and mass, as well as for the presence of cerebral white matter hyperintensities (WMHs), microbleeds and lacunar infarcts. Multivariate linear or logistic regression was performed to analyse the association between aortic PWV and outcome parameters, with covariates defined as age, gender, mean arterial pressure, heart rate, BMI, smoking, DM duration and hypertension. Mean aortic PWV was 7.1 {+-} 2.5 m/s. Aortic PWV was independently associated with LV ejection fraction (ss= -0.406, P = 0.006), LV stroke volume (ss=-0.407, P = 0.001), LV cardiac output (ss= -0.458, P = 0.001), and with cerebral WMHs (P < 0.05). There were no independent associations between aortic stiffness and LV mass, cerebral microbleeds or lacunar infarcts. Aortic stiffness is independently associated with systolic LV function and cerebral WMHs in patients with type 1 DM. (orig.)

  6. H-1 and N-15 resonance assignment of the second fibronectin type III module of the neural cell adhesion molecule

    DEFF Research Database (Denmark)

    Kiselyov, Vladislav V; Berezin, Vladimir; Bock, Elisabeth;

    2008-01-01

    We report here the NMR assignment of the second fibronectin type III module of the neural cell adhesion molecule (NCAM). This module has previously been shown to interact with the fibroblast growth factor receptor (FGFR), and the FGFR-binding site was mapped by NMR to the FG-loop region...... of the module. The FG-loop region also contains a putative nucleotide-binding motif, which was shown by NMR to interact with ATP. Furthermore, ATP was demonstrated to inhibit binding of the second F3 module of NCAM to FGFR....

  7. An all-optical switch of Mach-Zehnder interferometer type using an active fibre ring resonator

    Institute of Scientific and Technical Information of China (English)

    Li Jun-Qing; Alireza Bananej; Li Qiang-Hua; Chen Qiang; Li Chun-Fei

    2004-01-01

    We propose an all-optical switch of the Mach-Zehnder interferometer type using an active nonlinear ring resonatorand analyse the significance of the parameter A, a product of gain and total loss, for performing an ideal 1 by 2switch. We found that in the range of 1 - κ≤ A ≤√/1 - k, the increment of A can compensate the losses insidethe ring, therefore increase the finesse of the ring and enhance the nonlinearity contribution to reduce the switchingpower threshold effectively. We also emphasize the importance of the initial switching point and discuss the feasibilityof utilizing a high-nonlinear fibre in the ring.

  8. The Investigation of Separability of Particles Smaller Than 5 mm by Eddy Current Separation Technology. Part I: Rotating Type Eddy Current Separators

    NARCIS (Netherlands)

    Zhang, S.; Rem, P.C.; Forssberg, E.

    1999-01-01

    Owing to the growing emergence of the end-of-life electrical and electronic products with complex material structures and an ever-diminishing particle size of the valuable metals involved, development of eddy current separators (ECS) has been targeting selective separation of small non-ferrous metal

  9. Current medical treatment of diabetes type 2 and long term morbidity: how to balance efficacy and safety?

    Science.gov (United States)

    Carrera Boada, C A; Martínez-Moreno, J M

    2013-03-01

    Current medical treatment of type 2 diabetes mellitus (T2DM) requires special attention to different comorbidities that often are associated with hyperglycemia, such as overweight or obesity, dyslipidemia, hypertension, microvascular or macrovascular complications, etc. .. The control of these factors risk to health is as important as the glucose control in diabetes type 2, it is essential for the antidiabetes drugs consider these risk factors. The consensus statement published by the ADA/EASD and AACE emphasizes that the potential effects of antidiabetes medications on CV risk factors besides hyperglycemia (ie, overweight/obesity, hypertension, and dyslipidemia) should be considered in pharmacotherapy selection. Since T2DM is a progressive disease with worsening HbA1C values over time, monotherapy, even with different agents, will eventually fail to maintain the glycemic target. Because insulin resistance occurs in a variety of organs and tissues, many patients may achieve fasting glycemic control but develop postprandial hyperglycemia. Other issues include the risk for hypoglycaemia or weight gain with traditional glucose-lowering medications. The AACE/ACE algorithm for glycemic control is structured according to categories of HbA1C and suggests an HbA1C goal of =6.5%, although that may not be appropriate for all patients.42 The algorithm recommends monotherapy, dual therapy, or triple therapy based on initial HbA1C level of 6.5% to 7.5%, 7.6% to 9%, and >9% and reserves initiation of insulin therapy until treatment with oral or other injectable agents has failed. GLP-1 receptor agonists and DPP-4 inhibitors are novel options to improve glycemic control and reduce the incidence of weight gain. Combination therapy with newer and traditional agents improves glycemic control with a low incidence of hypoglycemia.

  10. Combination of high-resolution magic angle spinning proton magnetic resonance spectroscopy and microscale genomics to type brain tumor biopsies.

    Science.gov (United States)

    Tzika, A Aria; Astrakas, Loukas; Cao, Haihui; Mintzopoulos, Dionyssios; Andronesi, Ovidiu C; Mindrinos, Michael; Zhang, Jiangwen; Rahme, Laurence G; Blekas, Konstantinos D; Likas, Aristidis C; Galatsanos, Nikolas P; Carroll, Rona S; Black, Peter M

    2007-08-01

    Advancements in the diagnosis and prognosis of brain tumor patients, and thus in their survival and quality of life, can be achieved using biomarkers that facilitate improved tumor typing. We introduce and implement a combinatorial metabolic and molecular approach that applies state-of-the-art, high-resolution magic angle spinning (HRMAS) proton (1H) MRS and gene transcriptome profiling to intact brain tumor biopsies, to identify unique biomarker profiles of brain tumors. Our results show that samples as small as 2 mg can be successfully processed, the HRMAS 1H MRS procedure does not result in mRNA degradation, and minute mRNA amounts yield high-quality genomic data. The MRS and genomic analyses demonstrate that CNS tumors have altered levels of specific 1H MRS metabolites that directly correspond to altered expression of Kennedy pathway genes; and exhibit rapid phospholipid turnover, which coincides with upregulation of cell proliferation genes. The data also suggest Sonic Hedgehog pathway (SHH) dysregulation may play a role in anaplastic ganglioglioma pathogenesis. That a strong correlation is seen between the HRMAS 1H MRS and genomic data cross-validates and further demonstrates the biological relevance of the MRS results. Our combined metabolic/molecular MRS/genomic approach provides insights into the biology of anaplastic ganglioglioma and a new potential tumor typing methodology that could aid neurologists and neurosurgeons to improve the diagnosis, treatment, and ongoing evaluation of brain tumor patients.

  11. Fauna and habitat types driven by turbidity currents in the lobe complex of the Congo deep-sea fan

    Science.gov (United States)

    Sen, Arunima; Dennielou, Bernard; Tourolle, Julie; Arnaubec, Aurélien; Rabouille, Christophe; Olu, Karine

    2017-08-01

    This study characterizes the habitats and megafaunal community of the Congo distal lobe complex driven by turbidity currents through the use of remotely operated vehicle (ROV) still imagery transects covering distances in the order of kilometers. In this sedimentary, abyssal area about 5000 m deep and 750 km offshore from western Africa, large quantities of deposited organic material supplied by the Congo River canyon and channel support aggregations of large sized foraminifers (Bathysiphon sp.) and vesicomyid clams (Christineconcha regab, Abyssogena southwardae) often associated with methane cold seeps, as well as opportunistic deep-sea scavengers. Additionally, bacterial mats, assumed to be formed by large sulfur-oxidizing filamentous bacteria (Beggiatoa type), and black patches of presumably reduced sediment were seen which are, together with sulfur-oxidizing symbiont- bearing vesicomyids, indicators of sulfide-rich sediments. Habitat and faunal distribution were analyzed in relation to the microtopography obtained with the ROV multibeam echosounder, at three sites from the entrance of the lobe complex where the channel is still deep, to the main, flatter area of turbidite deposition. Specific characteristics of the system influence animal distributions: both the forams and the vesicomyid clams tended to avoid the channels characterized by high-speed currents, and are therefore preferentially located along channel flanks affected by sliding, and on levees formed by channel overspill. Foram fields are found in flat areas and form large fields, whereas the vesicomyids have a patchy distribution and appear to show a preference for regions of local topographical relief such as slide scars or collapsed blocks of sediments, which likely facilitate sulfide exhumation. The colonization of sulfide rich sediments by vesicomyids is limited, but nonetheless was seen to occur in the main deposition area where they have to cope with very high sedimentation rates (up to 20 cm

  12. Aging Reduces L-Type Calcium Channel Current and the Vasodilatory Response of Small Mesenteric Arteries to Calcium Channel Blockers

    Science.gov (United States)

    Albarwani, Sulayma A.; Mansour, Fathi; Khan, Abdul Aleem; Al-Lawati, Intisar; Al-Kaabi, Abdulla; Al-Busaidi, Al-Manar; Al-Hadhrami, Safa; Al-Husseini, Isehaq; Al-Siyabi, Sultan; Tanira, Musbah O.

    2016-01-01

    Calcium channel blockers (CCBs) are widely used to treat cardiovascular disease (CVD) including hypertension. As aging is an independent risk factor for CVD, the use of CCBs increases with increasing age. Hence, this study was designed to evaluate the effect of aging on the sensitivity of small mesenteric arteries to L-type voltage-gated calcium channel (LTCC) blockers and also to investigate whether there was a concomitant change in calcium current density. Third order mesenteric arteries from male F344 rats, aged 2.5–3 months (young) and 22–26 months (old) were mounted on wire myograph to measure the tension during isometric contraction. Arteries were contracted with 100 mM KCl and were then relaxed in a cumulative concentration-response dependent manner with nifedipine (0.1 nM–1 μM), verapamil (0.1 nM–10 μM), or diltiazem (0.1 nM–10 μM). Relaxation-concentration response curves produced by cumulative concentrations of three different CCBs in arteries of old rats were shifted to the right with statistically significant IC50s. pIC50 ± s.e.m: (8.37 ± 0.06 vs. 8.04 ± 0.05, 7.40 ± 0.07 vs. 6.81 ± 0.04, and 6.58 ± 0.07 vs. 6.34 ± 0.06) in young vs. old. It was observed that the maximal contractions induced by phenylephrine and reversed by sodium nitroprusside were not different between young and old groups. However, Bay K 8644 (1 μM) increased resting tension by 23 ± 4.8% in young arteries and 4.7 ± 1.6% in old arteries. LTCC current density were also significantly lower in old arteries (−2.77 ± 0.45 pA/pF) compared to young arteries (−4.5 ± 0.40 pA/pF); with similar steady-state activation and inactivation curves. Parallel to this reduction, the expression of Cav1.2 protein was reduced by 57 ± 5% in arteries from old rats compared to those from young rats. In conclusion, our results suggest that aging reduces the response of small mesenteric arteries to the vasodilatory effect of the CCBs and this may be due to, at least in part, reduced

  13. Aging Reduces L-type Calcium Channel Current and the Vasodilatory Response of Small Mesenteric Arteries to Calcium Channel Blockers

    Directory of Open Access Journals (Sweden)

    Sulayma A Albarwani

    2016-05-01

    Full Text Available Calcium channel blockers are widely used to treat cardiovascular disease (CVD including hypertension. As aging is an independent risk factor for CVD, the use of calcium channel blockers increases with increasing age. Hence, this study was designed to evaluate the effect of aging on the sensitivity of small mesenteric arteries to L-type voltage-gated calcium channel (LTCC blockers and also to investigate whether there was a concomitant change in calcium current density. Third order mesenteric arteries from male F344 rats, aged 2.5 - 3 months (young and 22 - 26 months (old were mounted on wire myograph to measure the tension during isometric contraction. Arteries were contracted with 100 mM KCl and were then relaxed in a cumulative concentration-response dependent manner with nifedipine (0.1nM - 10 µM, verapamil (0.1nM-10 µM or diltiazem (0.1nM - 10µM. Relaxation-concentration response curves produced by cumulative concentrations of three different calcium channel blockers (CCBs in arteries of old rats were shifted to the right with statistically significant IC50s. pEC50 ± s.e.m: (8.37 ± 0.06 vs 8.04 ± 0.05 , 7.40 ± 0.07 vs 6.81 ± 0.04 and 6.58 ± 0.07 vs 6.34 ± 0.06 in young vs old. It was observed that the maximal contractions induced by 100 mM KCl, phenylephrine and reversed by sodium nitroprusside were not different between young and old groups. However, Bay K 8644 increased resting tension by 23±4.8% in young arteries and 4.7±1.6% in old arteries. LTCC current density were also significantly lower in old arteries (-2.77 ± 0.45 pA/pF compared to young arteries (-4.5 ± 0.40 pA/pF; with similar steady-state activation and inactivation curves. Parallel to this reduction, the expression of Cav1.2 protein was reduced by 57 ± 5% in arteries from old rats compared to those from young rats. In conclusion, our results suggest that aging reduces the response of small mesenteric arteries to the vasodilatory effect of the CCBs and this may

  14. Quantum-size resonance tunneling in the field emission phenomenon

    Science.gov (United States)

    Litovchenko, V.; Evtukh, A.; Kryuchenko, Yu.; Goncharuk, N.; Yilmazoglu, O.; Mutamba, K.; Hartnagel, H. L.; Pavlidis, D.

    2004-07-01

    Theoretical analyses have been performed of the quantum-size (QS) resonance tunneling in the field-emission (FE) phenomenon for different models of the emitting structures. Such experimentally observed peculiarities have been considered as the enhancement of the FE current, the deviation from the Fowler-Nordheim law, the appearance of sharp current peaks, and a negative resistance. Different types of FE cathodes with QS structures (quantized layers, wires, or dots) have been studied experimentally. Resonance current peaks have been observed, from which the values of the energy-level splitting can be estimated.

  15. Ti/Pd/Ag Contacts to n-Type GaAs for High Current Density Devices

    Science.gov (United States)

    Huo, Pengyun; Rey-Stolle, Ignacio

    2016-06-01

    The metallization stack Ti/Pd/Ag on n-type Si has been readily used in solar cells due to its low metal/semiconductor specific contact resistance, very high sheet conductance, bondability, long-term durability, and cost-effectiveness. In this study, the use of Ti/Pd/Ag metallization on n-type GaAs is examined, targeting electronic devices that need to handle high current densities and with grid-like contacts with limited surface coverage (i.e., solar cells, lasers, or light emitting diodes). Ti/Pd/Ag (50 nm/50 nm/1000 nm) metal layers were deposited on n-type GaAs by electron beam evaporation and the contact quality was assessed for different doping levels (from 1.3 × 1018 cm-3 to 1.6 × 1019 cm-3) and annealing temperatures (from 300°C to 750°C). The metal/semiconductor specific contact resistance, metal resistivity, and the morphology of the contacts were studied. The results show that samples doped in the range of 1018 cm-3 had Schottky-like I- V characteristics and only samples doped 1.6 × 1019 cm-3 exhibited ohmic behavior even before annealing. For the ohmic contacts, increasing annealing temperature causes a decrease in the specific contact resistance ( ρ c,Ti/Pd/Ag ~ 5 × 10-4 Ω cm2). In regard to the metal resistivity, Ti/Pd/Ag metallization presents a very good metal conductivity for samples treated below 500°C ( ρ M,Ti/Pd/Ag ~ 2.3 × 10-6 Ω cm); however, for samples treated at 750°C, metal resistivity is strongly degraded due to morphological degradation and contamination in the silver overlayer. As compared to the classic AuGe/Ni/Au metal system, the Ti/Pd/Ag system shows higher metal/semiconductor specific contact resistance and one order of magnitude lower metal resistivity.

  16. The Profile of Patients and Current Practice of Treatment of Upper Limb Muscle Spasticity with Botulinum Toxin Type A: An International Survey

    Science.gov (United States)

    Bakheit, Abdel Magid

    2010-01-01

    To document the current practice in relation with the treatment of patients with upper limb spasticity with botulinum toxin type A to inform future research in this area. We designed an international, cross-sectional, noninterventional survey of current practice. Nine hundred and seventy-four patients from 122 investigational centres in 31…

  17. Current Transport in Copper Schottky Contacts to a-Plane/c-Plane n-Type MoSe2

    Institute of Scientific and Technical Information of China (English)

    C. K. Sumesh; K. D. Patel; V. M. Pathak; R. Srivastav

    2011-01-01

    @@ We identically prepared Cu-nMoSe2(a-plane) and Cu-nMoSe2(c-plane) Schottky barrier diodes(SBDs) on the same n-type MoSe2 single crystal.The effective Schottky barrier heights(SBHs) and ideality factors were obtained from the current-voltage-temperature(I-V-T) characteristics.The barrier height and ideality factor,estimated from the conventional thermionic emission model by assuming a Gaussian barrier distribution, are highly dependent on temperature.A notable deviation from the theoretical Richardson constant value is also observed in the conventional Richardson plot.The decrease in the experimental barrier height φBO and an increase in the ideality factor n with a decrease in temperature have been explained on the basis of barrier height inhomogeneities at the metal-semiconductor interface.It is proven that the presence of a distribution of barrier heights is responsible for the apparent decrease of the zero bias barrier height.The voltage dependence of the standard deviation causes the increase of the ideality factor at low temperatures.The value of the Richardson constant obtained without considering the inhomogeneous barrier heights is much closer than the theoretical value.The Cu-nMoSe2(a-plane) Schottky diode shows better results in comparison with the nMoSe2(c-plane)Schottky diode.

  18. Current Advances in the Biochemical and Physiological Aspects of the Treatment of Type 2 Diabetes Mellitus with Thiazolidinediones

    Science.gov (United States)

    Alemán-González-Duhart, D.; Tamay-Cach, F.; Álvarez-Almazán, S.

    2016-01-01

    The present review summarizes the current advances in the biochemical and physiological aspects in the treatment of type 2 diabetes mellitus (DM2) with thiazolidinediones (TZDs). DM2 is a metabolic disorder characterized by hyperglycemia, triggering the abnormal activation of physiological pathways such as glucose autooxidation, polyol's pathway, formation of advance glycation end (AGE) products, and glycolysis, leading to the overproduction of reactive oxygen species (ROS) and proinflammatory cytokines, which are responsible for the micro- and macrovascular complications of the disease. The treatment of DM2 has been directed toward the reduction of hyperglycemia using different drugs such as insulin sensitizers, as the case of TZDs, which are able to lower blood glucose levels and circulating triglycerides by binding to the nuclear peroxisome proliferator-activated receptor gamma (PPARγ) as full agonists. When TZDs interact with PPARγ, the receptor regulates the transcription of different genes involved in glucose homeostasis, insulin resistance, and adipogenesis. However, TZDs exhibit some adverse effects such as fluid retention, weight gain, hepatotoxicity, plasma-volume expansion, hemodilution, edema, bone fractures, and congestive heart failure, which limits their use in DM2 patients. PMID:27313601

  19. Value of dynamic 31p magnetic resonance spectroscopy technique in in vivo assessment of the skeletal muscle mitochondrial function in type 2 diabetes

    Institute of Scientific and Technical Information of China (English)

    WU Fei-yun; TU Hui-juan; QIN Bin; CHEN Ting; XU Hua-feng; QI Jing; WANG De-hang

    2012-01-01

    Background Phosphorous magnetic resonance spectroscopy (31p-MRS) has been successfully applied to study intracellular membrane compounds and high-energy phosphate metabolism.This study aimed to evaluate the capability of dynamic 31p-MRS for assessing energy metabolism and mitochondrial function in skeletal muscle from type 2 diabetic patients.Methods Dynamic 31p-MRS was performed on 22 patients with type 2 diabetes and 26 healthy volunteers.Spectra were acquired from quadriceps muscle while subjects were in a state of rest,at exercise and during recovery.The peak areas of inorganic phosphate (Pi),phosphocreatine (PCr),and adenosine triphosphate (ATP) were measured.The concentration of adenosine diphosphate (ADP) and the intracellular pH value were calculated from the biochemistry reaction equilibrium.The time constant and recovery rates of Pi,PCr,and ADP were analyzed using exponential curve fitting.Results As compared to healthy controls,type 2 diabetes patients had significantly lower skeletal muscle concentrations of Pi,PCr and β-ATP,and higher levels of ADP and Pi/PCr.During exercise,diabetics experienced a significant Pi peak increase and PCr peak decrease,and once the exercise was completed both Pi and PCr peaks returned to resting levels.Quantitatively,the mean recovery rates of Pi and PCr in diabetes patients were (10.74±1.26) mmol/s and (4.74±2.36) mmol/s,respectively,which was significantly higher than in controls.Conclusions Non-invasive quantitative 31P-MRS is able to detect energy metabolism inefficiency and mitochondrial function impairment in skeletal muscle of type 2 diabetics.

  20. Magnetic resonance of phase transitions

    CERN Document Server

    Owens, Frank J; Farach, Horacio A

    1979-01-01

    Magnetic Resonance of Phase Transitions shows how the effects of phase transitions are manifested in the magnetic resonance data. The book discusses the basic concepts of structural phase and magnetic resonance; various types of magnetic resonances and their underlying principles; and the radiofrequency methods of nuclear magnetic resonance. The text also describes quadrupole methods; the microwave technique of electron spin resonance; and the Mössbauer effect. Phase transitions in various systems such as fluids, liquid crystals, and crystals, including paramagnets and ferroelectrics, are also

  1. Development of cell-based quantitative evaluation method for cell cycle-arrest type cancer drugs for apoptosis by high precision surface plasmon resonance sensor

    Science.gov (United States)

    Ona, Toshihiro; Nishijima, Hiroshi; Kosaihira, Atsushi; Shibata, Junko

    2008-04-01

    In vitro rapid and quantitative cell-based assay is demanded to verify the efficacy prediction of cancer drugs since a cancer patient may have unconventional aspects of tumor development. Here, we show the rapid and non-label quantitative verifying method and instrumentation of apoptosis for cell cycle-arrest type cancer drugs (Roscovitine and D-allose) by reaction analysis of living liver cancer cells cultured on a sensor chip with a newly developed high precision (50 ndeg s -1 average fluctuation) surface plasmon resonance (SPR) sensor. The time-course cell reaction as the SPR angle change rate for 10 min from 30 min cell culture with a drug was significantly related to cell viability. By the simultaneous detection of differential SPR angle change and fluorescence by specific probes using the new instrument, the SPR angle was related to the nano-order potential decrease in inner mitochondrial membrane potential. The results obtained are universally valid for the cell cycle-arrest type cancer drugs, which mediate apoptosis through different cell-signaling pathways, by a liver cancer cell line of Hep G2 (P<0.001). This system towards the application to evaluate personal therapeutic potentials of drugs using cancer cells from patients in clinical use.

  2. Tumor segmentation of whole-body magnetic resonance imaging in neurofibromatosis type 1 patients: tumor burden correlates

    Energy Technology Data Exchange (ETDEWEB)

    Heffler, Michael A.; Xi, Yin; Chhabra, Avneesh [University of Texas Southwestern Medical Center, Department of Radiology, Dallas, TX (United States); Le, Lu Q. [University of Texas Southwestern Medical Center, Department of Dermatology, Dallas, TX (United States)

    2017-01-15

    Segmentation of whole-body MRI (WBMRI) to assess the feasibility, quantitate the total tumor volume (tumor burden) in patients with neurofibromatosis type 1 (NF1) and examine associations with demographic, disease-related and anthropomorphic features. A consecutive series of patients with NF1 underwent WBMRI and were reviewed for tumors. Tumors were segmented using a semiautomated software-based tool. Tumors were classified as superficial or deep and discrete or plexiform. Segmentation times were recorded. Segmentation yielded the quantity and tumor burden of superficial, internal and plexiform tumors. Correlations between segmentation data and demographic, disease-related and anthropomorphic features were examined. Fifteen patients were evaluated (42.3 ± 13.6 years, 10 female, 5 male). Segmentation times were a median of 30 min and yielded 2,328 tumors (1,582 superficial, 746 internal and 23 plexiform). One tumor was malignant. Tumor counts ranged from 14 to 397. Tumor burden ranged from 6.95 cm3 to 571 cm3. Individual tumor volume ranged from 0.0120 cm3 to 298 cm3. Significant correlation was found between the total volume of superficial tumors and height (ρ = 0.5966, p < 0.02). Male patients had higher overall tumor burdens (p < 0.05) and higher superficial tumor burden (p < 0.03). Patients with negative family history had more tumors (p < 0.05). Segmentation of WBMRI in patients with NF1 is feasible and elucidates meaningful relationships among disease phenotype, anthropomorphic and demographic features. (orig.)

  3. The Description of Extremely Short Pulses in Non-Resonant Media in Frame of Maxwell-Duffing-Type Models

    Science.gov (United States)

    Kazantseva, Elena V.

    The propagation of extremely short pulses of electromagnetic field (electromagnetic spikes) is considered in the framework of a model where the material medium is represented by anharmonic oscillators with cubic nonlinearities (Duffing model) and waves can propagate in both directions. The system of total Maxwell-Duffing equations admits two families of exact analytical solutions in the form of solitary waves. The single-cycle electromagnetic pulse propagation in a medium whose dispersion and nonlinear properties are described by the cubic-quintic Duffing model (oscillator with third- and fifth-order anharmonicity). A system of equations governing the evolution of a unidirectional electromagnetic wave is analyzed without using the approximation of slowly varying envelopes. Three types of solutions of this system describing stationary propagation of a pulse in such a medium are found. When the signs of the anharmonicity constants are different, the amplitude of a steady-state pulse is limited, but its energy may grow on account of an increase in its duration.

  4. Sequential NMR resonance assignment and structure determination of the Kunitz-type inhibitor domain of the Alzheimer's beta-amyloid precursor protein.

    Science.gov (United States)

    Heald, S L; Tilton, R F; Hammond, L J; Lee, A; Bayney, R M; Kamarck, M E; Ramabhadran, T V; Dreyer, R N; Davis, G; Unterbeck, A

    1991-10-29

    Certain precursor proteins (APP751 and APP770) of the amyloid beta-protein (AP) present in Alzheimer's disease contain a Kunitz-type serine protease inhibitor domain (APPI). In this study, the domain is obtained as a functional inhibitor through both recombinant (APPIr) and synthetic (APPIs) methodologies, and the solution structure of APPI is determined by 1H 2D NMR techniques. Complete sequence-specific resonance assignments (except for P13 and G37 NH) for both APPIr and APPIs are achieved using standard procedures. Ambiguities arising from degeneracies in the NMR resonances are resolved by varying sample conditions. Qualitative interpretation of short- and long-range NOEs reveals secondary structural features similar to those extensively documented by NMR for bovine pancreatic trypsin inhibitor (BPTI). A more rigorous interpretation of the NOESY spectra yields NOE-derived interresidue distance restraints which are used in conjunction with dynamic simulated annealing to generate a family of APPI structures. Within this family, the beta-sheet and helical regions are in good agreement with the crystal structure of BPTI, whereas portions of the protease-binding loops deviate from those in BPTI. These deviations are consistent with those recently described in the crystal structure of APPI (Hynes et al., 1990). Also supported in the NMR study is the hydrophobic patch in the protease-binding domain created by side chain-side chain NOE contacts between M17 and F34. In addition, the NMR spectra indicate that the rotation of the W21 ring in APPI is hindered, unlike Y21 in BPTI, showing a greater than 90% preference for one orientation in the hydrophobic groove.

  5. Minimum quench power dissipation and current non-uniformity in international thermonuclear experimental reactor type NbTi cable-in-conduit conductor samples under direct current conditions

    Science.gov (United States)

    Rolando, G.; van Lanen, E. P. A.; Nijhuis, A.

    2012-05-01

    The level of current non-uniformity in NbTi cable-in-conduit conductors (CICCs) sections near the joints in combination with the magnetic field profile needs attention in view of proper joint design. The strand joule power and current distribution at quench under DC conditions of two samples of ITER poloidal field coil conductors, as tested in the SULTAN facility, and of the so called PFCI model coil insert, have been analyzed with the numerical cable model JackPot. The precise trajectories of all individual strands, joint design, cabling configuration, spatial distribution of the magnetic field, sample geometry, and experimentally determined interstrand resistance distributions have been taken into account. Although unable to predict the quench point due to the lack of a thermal-hydraulic routine, the model allows to assess the instantaneous strand power at quench and its local distribution in the cable once the quench conditions in terms of current and temperature are experimentally known. The analysis points out the relation of the above mentioned factors with the DC quench stability of both short samples and coils. The possible small scale and local electrical-thermal interactions were ignored in order to examine the relevance of such effects in the overall prediction of the CICC performance. The electromagnetic code shows an excellent quantitative predictive potential for CICC transport properties, excluding any freedom for matching the results. The influence of the local thermal effects in the modeling is identified as being marginal and far less than the generally accepted temperature margin for safe operation.

  6. Pharmacological profile of the ATP-mediated increase in L-type calcium current amplitude and activation of a non-specific cationic current in rat ventricular cells.

    OpenAIRE

    Scamps, F.; Vassort, G.

    1994-01-01

    1. The pharmacological profile of the ATP-induced increase in ICa amplitude and of ATP activation of a non-specific cationic current, IATP, was investigated in rat ventricular cells. 2. The EC50 values for ICa increase and IATP activation were 0.36 microM and 0.76 microM respectively. Suramin (10 microM) and cibacron blue (1 microM) competitively antagonized both effects of ATP. 3. The rank order of efficacy and potency of ATP analogues in increasing ICa amplitude was 2-methylthio-ATP approxi...

  7. Phosphodiesterase 5 restricts NOS3/Soluble guanylate cyclase signaling to L-type Ca2+ current in cardiac myocytes.

    Science.gov (United States)

    Wang, Honglan; Kohr, Mark J; Traynham, Christopher J; Ziolo, Mark T

    2009-08-01

    Endothelial nitric oxide synthase (NOS3) regulates the functional response to beta-adrenergic (beta-AR) stimulation via modulation of the L-type Ca(2+) current (I(Ca)). However, the NOS3 signaling pathway modulating I(Ca) is unknown. This study investigated the contribution of soluble guanylate cyclase (sGC) and phosphodiesterase type 5 (PDE5), a cGMP-specific PDE, in the NOS3-mediated regulation of I(Ca). Myocytes were isolated from NOS3 knockout (NOS3(-/-)) and wildtype (WT) mice. We measured I(Ca) (whole-cell voltage-clamp), and simultaneously measured Ca(2+) transients (Fluo-4 AM) and cell shortening (edge detection). Zaprinast (selective inhibitor of PDE5), decreased beta-AR stimulated (isoproterenol, ISO)-I(Ca), and Ca(2+) transient and cell shortening amplitudes in WT myocytes. However, YC-1 (NO-independent activator of sGC) only reduced ISO-stimulated I(Ca), but not cardiac contraction. We further investigated the NOS3/sGC/PDE5 pathway in NOS3(-/-) myocytes. PDE5 is mislocalized in these myocytes and we observed dissimilar effects of PDE5 inhibition and sGC activation compared to WT. That is, zaprinast had no effect on ISO-stimulated I(Ca), or Ca(2+) transient and cell shortening amplitudes. Conversely, YC-1 significantly decreased both ISO-stimulated I(Ca), and cardiac contraction. Further confirming that PDE5 localizes NOS3/cGMP signaling to I(Ca); YC-1, in the presence of zaprinast, now significantly decreased ISO-stimulated Ca(2+) transient and cell shortening amplitudes in WT myocytes. The effects of YC-1 on I(Ca) and cardiac contraction were blocked by KT5823 (a selective inhibitor of the cGMP-dependent protein kinase, PKG). Our data suggests a novel physiological role for PDE5 in restricting the effects of NOS3/sGC/PKG signaling pathway to modulating beta-AR stimulated I(Ca), while limiting effects on cardiac contraction.

  8. The beta-adrenergic blocker carvedilol restores L-type calcium current in a myocardial infarction model of rabbit

    Institute of Scientific and Technical Information of China (English)

    LI Xia; HUANG Cong-xin; JIANG Hong; CAO Feng; WANG Teng

    2005-01-01

    Background Carvedilol, an antagonist of α1- and β-adrenergic receptors, has shown efficacy in reducing all-cause death and arrhythmia death for ischemic heart disease and congestive heart failure in several large-scale trials. It has been found to prevent ventricular remodeling, and recently was reported to reverse down-regulation of Na+ channel in a chronic heart failure model. This study was conducted to investigate whether carvedilol could reverse the ion remodeling in a myocardial infarction model of rabbit.Methods After the procedure of coronary ligation, animals were randomized to placebo or carvedilol treatment (5 mg/kg). Action potentials, L-type calcium current (Ica L) and the effect of isoproterenol stimulation on Ica L were measured using whole-cell patch method. Evaluation of the expression of calcium channel subunits was carried out by RT-PCR and Western blot. Results The results indicate that mean peak Ica L densities (pA/pF) at +10 mV was reduced in postinfarction myocytes (5.33±0.45, n=25) compared to sham myocytes (6.52±0.21, n=20). Treatment of myocardial infarction rabbits with carvedilol could restore it partially (5.91±0.39, n=20, P<0.05). However, steady-state activation parameters were similar in three groups. With stimulation by isoproterenol (1 μmol/L) Ica L increased in all three groups, but the increase was smaller in postinfarction myocytes. mRNA levels of calcium channel subunit CaA1 gene was decreased but CaB2a, CaB2b and CaB3 mRNA levels did not change after MI. Corresponding change in CaA1 protein was also observed. Conclusions The results demonstrate that carvedilol restores Ica L density and reverse the downregulation of CaA1 postinfarction.

  9. Effects of AMP579 and adenosine on L-type Ca2+ current in isolated rat ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    Xiong WANG; Bo-wei WU; Dong-mei WU

    2005-01-01

    Aim: To compare the effects of AMP579 and adenosine on L-type Ca2+ current (ICa- L) in rat ventricular myocytes and explore the mechanism by which AMP579 acts on ICa-L. Methods: ICa-L was recorded by patch-clamp technique in whole-cell configuration. Results: Adenosine (10 nmol/L to 50 μmol/L) showed no effect on basal ICa- L, but it inhibited the ICa-L induced by isoproterenol 10 nmol/L in a concen tration-dependent manner with the IC50 of 13.06 μmol/L. Similar to adenosine,AMP579 also showed an inhibitory effect on the ICa-L induced by isoproterenol.AMP579 and adenosine (both in 10 μmol/L) suppressed isoproterenol-induced ICa-L by 11.1% and 5.2%, respectively. In addition, AMP579 had a direct inhibitory effect on basal ICa-L in a concentration-dependent manner with IC50 (1.17 μmol/L).PD116948 (30 μmol/L), an adenosine A1 receptor blocker, showed no action on the inhibitory effect of AMP579 on basal ICa-L. However, GF109203X (0.4 μmol/L), a special protein kinase C (PKC) blocker, could abolish the inhibitory effect of AMP579 on basal ICa-L. So the inhibitory effect of AMP579 on basal ICa-L was induced through activating PKC, but not linked to adenosine A1 receptor. Conclusion:AMP579 shows a stronger inhibitory effect than adenosine on the ICa-L induced by isoproterenol. AMP579 also has a strong inhibitory effect on basal ICa-L in rat ventricular myocytes. Activation of PKC is involved in the inhibitory effect of AMP579 on basal ICa-L at downstream-mechanism.

  10. Mediation Role of C-Reactive Protein on the Association between Smoking Quantity and Type 2 Diabetes in Current Chinese Smokers

    Directory of Open Access Journals (Sweden)

    Dan Feng

    2014-01-01

    Full Text Available Objective. Previous studies have indicated that cigarette smokers are more likely to develop type 2 diabetes and that both smoking and type 2 diabetes are associated with C-reactive protein (CRP. This study examined whether CRP mediates the association between smoking quantity and type 2 diabetes. Methods. Nine hundred and eighty-four current Chinese smokers were selected from a community-based chronic disease survey conducted in Guangzhou and Zhuhai. Type 2 diabetes was defined according to the WHO 1999 criteria. CRP was measured with flow cytometry. Binary logistic regression was performed to assess the mediation. Results. A positive association was observed between smoking quantity and type 2 diabetes (P<0.05. After controlling for potential confounders, daily cigarette consumption was significantly associated with higher CRP levels. Current smokers with type 2 diabetes had higher CRP levels than smokers without type 2 diabetes. The association between the smoking quantity and type 2 diabetes was mediated by CRP, which accounted for 50.77% of the association. Conclusions. This study provides further evidence that smoking quantity is positively associated with type 2 diabetes and suggests that the association between smoking and type 2 diabetes might be mediated by CRP.

  11. A New Application of the Multi-Resonant Zero-Current Switching Buck Converter: Analysis and Simulation in a PMSG Based WECS

    Directory of Open Access Journals (Sweden)

    Tiara Freitas

    2015-09-01

    Full Text Available A new application of the three-phase buck-resonant converter is presented in this paper. It is shown that the analyzed converter is suitable to operate as the rectifier stage in low power wind energy conversion systems (WECS based on permanent magnet synchronous generators (PMSG with variable wind speed. As main features, it presents a single controlled switch, simple implementation and control, and operates with a high power factor and low harmonic distortion over all wind speed ranges. The converter topology, its design equations and its operation are presented, as well as the simulation results of the PMSG based conversion system. From the analysis carried out in the paper it is concluded that the converter is indicated to be employed in distributed generation and hybrid systems where wind generation is associated with other sources.

  12. Lipoprotein subclass measurements by Nuclear Magnetic Resonance Spectroscopy improve the prediction of Coronary Artery disease in type 1 diabetes. A prospective report from the Pittsburgh Epidemiology of Diabetes Complications study

    NARCIS (Netherlands)

    Soedamah-Muthu, S.S.; Chang, Y.F.; Otvos, J.; Evans, R.W.; Orchard, T.J.

    2003-01-01

    Aim/hypothesis. To examine whether nuclear magnetic resonance lipoprotein spectroscopy improves the prediction of coronary artery disease in patients with Type 1 diabetes, independently of conventional lipid and other risk factors. Methods. A prospective nested case-control design of subjects with

  13. Computational modeling of distinct neocortical oscillations driven by cell-type selective optogenetic drive: Separable resonant circuits controlled by low-threshold spiking and fast-spiking interneurons

    Directory of Open Access Journals (Sweden)

    Dorea Vierling-Claassen

    2010-11-01

    Full Text Available Selective optogenetic drive of fast spiking interneurons (FS leads to enhanced local field potential (LFP power across the traditional gamma frequency band (20-80Hz; Cardin et al., 2009. In contrast, drive to regular-spiking pyramidal cells (RS enhances power at lower frequencies, with a peak at 8 Hz. The first result is consistent with previous computational studies emphasizing the role of FS and the time constant of GABAA synaptic inhibition in gamma rhythmicity. However, the same theoretical models do not typically predict low-frequency LFP enhancement with RS drive. To develop hypotheses as to how the same network can support these contrasting behaviors, we constructed a biophysically principled network model of primary somatosensory neocortex containing FS, RS and low-threshold-spiking (LTS interneurons. Cells were modeled with detailed cell anatomy and physiology, multiple dendritic compartments, and included active somatic and dendritic ionic currents. Consistent with prior studies, the model demonstrated gamma resonance during FS drive, dependent on the time-constant of GABAA inhibition induced by synchronous FS activity. Lower frequency enhancement during RS drive was replicated only on inclusion of an inhibitory LTS population, whose activation was critically dependent on RS synchrony and evoked longer-lasting inhibition. Our results predict that differential recruitment of FS and LTS inhibitory populations is essential to the observed cortical dynamics and may provide a means for amplifying the natural expression of distinct oscillations in normal cortical processing.

  14. Self-monitoring of blood glucose in type 2 diabetic patients in China:current status and influential factors

    Institute of Scientific and Technical Information of China (English)

    Yuan Li; Guo Xiaohui; Xiong Zhenzhen; Lou Qingqing; Shen Li; Zhao Fang; Sun Zilin

    2014-01-01

    Background Self-monitoring of blood glucose (SMBG) by individuals with type 2 diabetes (T2D) is crucial for long-term health,yet numerous cultural,economic and health factors can reduce SMBG.Most studies on SMBG adherence have come out of the US and Europe,and their relevance to Asia is unclear.The aims of the present study were to assess the current state of SMBG in China and analyze demographic and diabetes-related characteristics that may influence it.Methods In this multi-center,cross-sectional study,5 953 individuals with T2D from 50 medical centers in 29 provinces across China filled out a standardized questionnaire that requested information on demographic characteristics,education level,occupation,income,lifestyle risk factors,duration of diabetes,chronic complications,and frequency of SMBG.Respondents were also asked whether their glycosylated hemoglobin (HbA1c) had been checked in the past 6 months.The most recent values for fasting plasma glucose,2-hour postprandial blood glucose and HbA1c were recovered from medical records.Results Only 1 130 respondents (18.98%) performed SMBG with the recommended frequency,while 4 823 (81.02%) did not.In fact,nearly 2 105 (35.36%) reported never performing SMBG.In the subset of 3 661 individuals on insulin therapy,only 266 (7.27%) performed SMBG at least once a day,while 1 210 (33.05%) never performed it.In contrast,895 of 2 292 individuals (39.05%) on diet/exercise therapy or oral hypoglycemic therapy never performed it.Multivariate Logistic regression identified several factors associated with SMBG adherence:female gender,higher education level,higher income,longer T2D duration and education about SMBG.Conclusions SMBG adherence in our Chinese population with T2D was less frequent than that in developed countries.Several factors influence SMBG adherence:gender,education level,income,T2D duration,therapy regimen and exposure to education about SMBG.

  15. Magnetic resonance diffusion tensor imaging (MRDTI) of the optic nerve and optic radiations at 3T in children with neurofibromatosis type I (NF-1)

    Energy Technology Data Exchange (ETDEWEB)

    Filippi, Christopher G.; Nickerson, Joshua P. [University of Vermont School of Medicine-FAHC, Department of Radiology, Burlington, VT (United States); Bos, Aaron [University of Vermont School of Medicine, Burlington, VT (United States); Salmela, Michael B. [University of Minnesota School of Medicine, Department of Radiology, Minneapolis, MN (United States); Koski, Chris J. [James Madison University, Department of Political Sciences, Harrisonburg, VA (United States); Cauley, Keith A. [University of Massachusetts Memorial Medical Center, Department of Radiology, Worcester, MA (United States)

    2012-02-15

    Optic pathway glioma (OPG) is a characteristic hallmark of neurofibromatosis type I (NF-I). To evaluate the feasibility of magnetic resonance diffusion tensor imaging (MRDTI) at 3T to detect abnormalities of the optic nerves and optic radiations in children with NF-I. 3-T MRDTI was prospectively performed in 9 children with NF-I (7 boys, 2 girls, average age 7.8 years, range 3-17 years) and 44 controls (25 boys, 19 girls, average age 8.1 years, range 3-17 years). Fractional anisotropy (FA) and mean diffusivity were determined by region-of-interest analysis for the optic nerves and radiations. Statistical analysis compared controls to NF-I patients. Two NF-I patients had bilateral optic nerve gliomas, three had chiasmatic gliomas and four had unidentified neurofibromatosis objects (UNOs) along the optic nerve pathways. All NF-I patients had statistically significant decreases in FA and elevations in mean diffusivity in the optic nerves and radiations compared to age-matched controls. MRDTI can evaluate the optic pathways in children with NF-I. Statistically significant abnormalities were detected in the diffusion tensor metrics of the optic nerves and radiations in children with NF-I compared to age-matched controls. (orig.)

  16. Quaternary ammonium oxidative demethylation: X-ray crystallographic, resonance Raman, and UV-visible spectroscopic analysis of a Rieske-type demethylase.

    Science.gov (United States)

    Daughtry, Kelly D; Xiao, Youli; Stoner-Ma, Deborah; Cho, Eunsun; Orville, Allen M; Liu, Pinghua; Allen, Karen N

    2012-02-08

    Herein, the structure resulting from in situ turnover in a chemically challenging quaternary ammonium oxidative demethylation reaction was captured via crystallographic analysis and analyzed via single-crystal spectroscopy. Crystal structures were determined for the Rieske-type monooxygenase, stachydrine demethylase, in the unliganded state (at 1.6 Å resolution) and in the product complex (at 2.2 Å resolution). The ligand complex was obtained from enzyme aerobically cocrystallized with the substrate stachydrine (N,N-dimethylproline). The ligand electron density in the complex was interpreted as proline, generated within the active site at 100 K by the absorption of X-ray photon energy and two consecutive demethylation cycles. The oxidation state of the Rieske iron-sulfur cluster was characterized by UV-visible spectroscopy throughout X-ray data collection in conjunction with resonance Raman spectra collected before and after diffraction data. Shifts in the absorption band wavelength and intensity as a function of absorbed X-ray dose demonstrated that the Rieske center was reduced by solvated electrons generated by X-ray photons; the kinetics of the reduction process differed dramatically for the liganded complex compared to unliganded demethylase, which may correspond to the observed turnover in the crystal.

  17. Förster Resonance Energy Transfer (FRET as a Tool for Dissecting the Molecular Mechanisms for Maturation of the Shigella Type III Secretion Needle Tip Complex

    Directory of Open Access Journals (Sweden)

    William D. Picking

    2012-11-01

    Full Text Available Förster resonance energy transfer (FRET provides a powerful tool for monitoring intermolecular interactions and a sensitive technique for studying Å-level protein conformational changes. One system that has particularly benefited from the sensitivity and diversity of FRET measurements is the maturation of the Shigella type III secretion apparatus (T3SA needle tip complex. The Shigella T3SA delivers effector proteins into intestinal cells to promote bacterial invasion and spread. The T3SA is comprised of a basal body that spans the bacterial envelope and a needle with an exposed tip complex that matures in response to environmental stimuli. FRET measurements demonstrated bile salt binding by the nascent needle tip protein IpaD and also mapped resulting structural changes which led to the recruitment of the translocator IpaB. At the needle tip IpaB acts as a sensor for host cell contact but prior to secretion, it is stored as a heterodimeric complex with the chaperone IpgC. FRET analyses showed that chaperone binding to IpaB’s N-terminal domain causes a conformational change in the latter. These FRET analyses, with other biophysical methods, have been central to understanding T3SA maturation and will be highlighted, focusing on the details of the FRET measurements and the relevance to this particular system.

  18. The lead acceptor in p-type natural 2H-polytype MoS2 crystals evidenced by electron paramagnetic resonance

    Science.gov (United States)

    Iacovo, S.; Stesmans, A.; Houssa, M.; Afanas'ev, V. V.

    2017-03-01

    A low-temperature (T  =  1.5-8 K) electron paramagnetic resonance study of p-type 2H-polytype natural MoS2 crystals reveals a previously unreported anisotropic signal of corresponding defect density (spin S  =  ½) ~5  ×  1014 cm-3. For the applied magnetic field B//c-axis, the response is comprised of a single central asymmetric Zeeman peak at zero-crossing g  =  2.102(1), amid a symmetrically positioned hyperfine doublet of splitting 6.6(2) G. Field angular observations reveal a two-branch g pattern, indicative of a defect of lower than axial symmetry, likely orthorhombic (C 2v). Based on the signal specifics, it is ascribed to a system of decoupled Pb impurities substituting for Mo, the defect operating as an acceptor, with estimated thermal activation energy  >10 meV. Supporting theoretical anticipation, the results pinpoint the conduct of the Pb impurity in layered MoS2.

  19. Combining magnetic resonance spectroscopy and molecular genomics offers better accuracy in brain tumor typing and prediction of survival than either methodology alone.

    Science.gov (United States)

    Astrakas, Loukas; Blekas, Konstantinos D; Constantinou, Caterina; Andronesi, Ovidiu C; Mindrinos, Michael N; Likas, Aristidis C; Rahme, Laurence G; Black, Peter M; Marcus, Karen J; Tzika, A Aria

    2011-04-01

    Recent advents in magnetic resonance spectroscopy (MRS) techniques permit subsequent microarray analysis over the entire human transcriptome in the same tissue biopsies. However, extracting information from such immense quantities of data is limited by difficulties in recognizing and evaluating the relevant patterns of apparent gene expression in the context of the existing knowledge of phenotypes by histopathology. Using a quantitative approach derived from a knowledge base of pathology findings, we present a novel methodology used to process genome-wide transcription and MRS data. This methodology was tested to examine metabolite and genome-wide profiles in MRS and RNA in 55 biopsies from human subjects with brain tumors with ~100% certainty. With the guidance of histopathology and clinical outcome, 15 genes with the assistance of 15 MRS metabolites were able to be distinguished by tumor categories and the prediction of survival was better than when either method was used alone. This new method, combining MRS, genomics, statistics and biological content, improves the typing and understanding of the complexity of human brain tumors, and assists in the search for novel tumor biomarkers. It is an important step for novel drug development, it generates testable hypotheses regarding neoplasia and promises to guide human brain tumor therapy provided improved in vivo methods for monitoring response to therapy are developed.

  20. Battery voltage-balancing applications of disk-type radial mode Pb(Zr • Ti)O3 ceramic resonator

    Science.gov (United States)

    Thenathayalan, Daniel; Lee, Chun-gu; Park, Joung-hu

    2017-10-01

    In this paper, we propose a novel technique to build a charge-balancing circuit for series-connected battery strings using various kinds of disk-type ceramic Pb(Zr • Ti)O3 piezoelectric resonators (PRs). The use of PRs replaces the whole external battery voltage-balancer circuit, which consists mainly of a bulky magnetic element. The proposed technique is validated using different ceramic PRs and the results are analyzed in terms of their physical properties. A series-connected battery string with a voltage rating of 61.5 V is set as a hardware prototype under test, then the power transfer efficiency of the system is measured at different imbalance voltages. The performance of the proposed battery voltage-balancer circuit employed with a PR is also validated through hardware implementation. Furthermore, the temperature distribution image of the PR is obtained to compare power transfer efficiency and thermal stress under different operating conditions. The test results show that the battery voltage-balancer circuit can be successfully implemented using PRs with the maximum power conversion efficiency of over 96% for energy storage systems.

  1. Current-induced destruction of type I superconductivity: The role of the one- and two-dimensional mixed state

    Science.gov (United States)

    Robin, D.; Rinderer, L.; Posada, E.

    1982-02-01

    New experimental and theoretical results on the current-induced phase transition in cylindrical wires (tin) are presented: The London model for the intermediate state of current-carrying superconductors has been modified, taking into account magnetoresistance, and has been extended to hollow cylinders. Evidence for the one- and two-dimensional mixed state first proposed by Landau has been obtained from the study of the quasistatic voltage-current curves of solid and hollow cylindrical specimens, respectively. The kinetic phenomena during the current-induced destruction of superconductivity in solid cylindrical wires have previously been studied by Posada and Rinderer, but only measurements on hollow wires of high purity presented in this paper confirm the isothermal electromagnetic theory of Rothen and Bestgen for a current-induced phase transition. For currents close to Silsbee's critical current, in pure specimens as well as for impure specimens, for any current above the critical, the dynamic destruction of superconductivity in wires is no longer isothermal. For these cases the nonisothermal theory of Posada and Rinderer has been extended to the case of hollow cylinders and successfully compared with experiments.

  2. Projection of bootstrap current in the ITER with standard type I ELMy H-mode and steady state scenarios

    Directory of Open Access Journals (Sweden)

    Thawatchai Onjun

    2012-02-01

    Full Text Available The investigation of bootstrap current formation in ITER is carried out using BALDUR integrated predictive modelingcode. The combination of Mixed B/gB anomalous transport model and NLCASS module together with the pedestal model isused in BALDUR code to simulate the time evolution of temperature, density, and plasma current profiles. It was found inthe simulations that without the presence of ITB, a minimal fraction of bootstrap current (as well as low fusion performancewas achieved. The enhancement due to ITB depends sensitively on the strength of toroidal velocity. A sensitivity study wasalso carried out to optimize the bootstrap current fraction and plasma performance. It was found that the bootstrap currentfraction slightly improved; while the plasma performance greatly improved with increasing of NBI power or pedestal temperature.On the other hand, higher impurity concentration resulted in a significant degradation of fusion performance, buta smaller degradation in bootstrap current.

  3. Triple-resonant transducers.

    Science.gov (United States)

    Butler, Stephen C

    2012-06-01

    A detailed analysis is presented of two novel multiple-resonant transducers which produce a wider transmit response than that of a conventional Tonpilz-type transducer. These multi-resonant transducers are Tonpilz-type longitudinal vibrators that produce three coupled resonances and are referred to as triple-resonant transducers (TRTs). One of these designs is a mechanical series arrangement of a tail mass, piezoelectric ceramic stack, central mass, compliant spring, second central mass, second compliant spring, and a piston-radiating head mass. The other TRT design is a mechanical series arrangement of a tail mass, piezoelectric ceramic stack, central mass, compliant spring, and head mass with a quarter-wave matching layer of poly(methyl methacrylate) on the head mass. Several prototype transducer element designs were fabricated that demonstrated proof-of-concept.

  4. Dual actions of enflurane on postsynaptic currents abolished by the gamma-aminobutyric acid type A receptor beta3(N265M) point mutation.

    Science.gov (United States)

    Drexler, Berthold; Jurd, Rachel; Rudolph, Uwe; Antkowiak, Bernd

    2006-08-01

    At concentrations close to 1 minimum alveolar concentration (MAC)-immobility, volatile anesthetics display blocking and prolonging effects on gamma-aminobutyric acid type A receptor-mediated postsynaptic currents. It has been proposed that distinct molecular mechanisms underlie these dual actions. The authors investigated whether the blocking or the prolonging effect of enflurane is altered by a point mutation (N265M) in the beta3 subunit of the gamma-aminobutyric acid type A receptor. Furthermore, the role of the beta3 subunit in producing the depressant actions of enflurane on neocortical neurons was elucidated. Spontaneous inhibitory postsynaptic currents were sampled from neocortical neurons in cultured slices derived from wild-type and beta3(N265M) mutant mice. The effects of 0.3 and 0.6 mm enflurane on decay kinetics, peak amplitude, and charge transfer were quantified. Furthermore, the impact of enflurane-induced changes in spontaneous action potential firing was evaluated by extracellular recordings in slices from wild-type and mutant mice. In slices derived from wild-type mice, enflurane prolonged inhibitory postsynaptic current decays and decreased peak amplitudes. Both effects were almost absent in slices from beta3(N265M) mutant mice. At clinically relevant concentrations between MAC-awake and MAC-immobility, the anesthetic was less effective in depressing spontaneous action potential firing in slices from beta3(N265M) mutant mice compared with wild-type mice. At concentrations between MAC-awake and MAC-immobility, beta3-containing gamma-aminobutyric acid type A receptors contribute to the depressant actions of enflurane in the neocortex. The beta3(N265M) mutation affects both the prolonging and blocking effects of enflurane on gamma-aminobutyric acid type A receptor-mediated inhibitory postsynaptic currents in neocortical neurons.

  5. High current H{sub 2}{sup +} and H{sub 3}{sup +} beam generation by pulsed 2.45 GHz electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yuan; Peng, Shixiang, E-mail: sxpeng@pku.edu.cn; Ren, Haitao; Zhao, Jie; Chen, Jia; Zhang, Tao; Guo, Zhiyu [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, Peking University, Beijing 100871 (China); Zhang, Ailin [University of Chinese Academy of Sciences, Beijing 100049 (China); Chen, Jia' er [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, Peking University, Beijing 100871 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2014-02-15

    The permanent magnet 2.45 GHz electron cyclotron resonance ion source at Peking University can produce more than 100 mA hydrogen ion beam working at pulsed mode. For the increasing requirements of cluster ions (H{sub 2}{sup +} and H{sub 3}{sup +}) in linac and cyclotron, experimental study was carried out to further understand the hydrogen plasma processes in the ion source for the generation of cluster ions. The constituents of extracted beam have been analyzed varying with the pulsed duration from 0.3 ms to 2.0 ms (repetition frequency 100 Hz) at different operation pressure. The fraction of cluster ions dramatically increased when the pulsed duration was lower than 0.6 ms, and more than 20 mA pure H{sub 3}{sup +} ions with fraction 43.2% and 40 mA H{sub 2}{sup +} ions with fraction 47.7% were obtained when the operation parameters were adequate. The dependence of extracted ion fraction on microwave power was also measured at different pressure as the energy absorbed by plasma will greatly influence electron temperature and electron density then the plasma processes in the ion source. More details will be presented in this paper.

  6. A feasibility study of full-bridge type superconducting fault current controller on electric machine power stability

    Science.gov (United States)

    Jang, J. Y.; Hwang, Y. J.; Lee, J.; Ko, T. K.

    2016-02-01

    Recently, because of the advent of Smart Grid and integration of distributed generations, electrical power grids are facing uncountable challenges. Increase of fault current is one of such serious challenges and there are some fault current limiters (FCLs) that can limit the fault current. Existing grid protection FCLs, however, simply limit the fault current passively and can allow the existing protection coordination schemes to fail. This phenomenon leads to catastrophic failure in the complex system and may cause unpredictable power grid operation. Unlike a FCL, a superconducting fault current controller (SFCC) employs a full-bridge thyristor rectifier, a high temperature superconducting (HTS) DC reactor, and an embedded control unit to maintain the fault current level at a proper value by adjusting the phase angle of thyristors. This paper contains experimental and numerical analysis to design and fabricate a SFCC system for protection and stability improvement in power grids. At first, fundamental characteristics of a SFCC system were introduced. System circuit diagram and operational principles were proposed. Secondly, the developed small-scale SFCC system was introduced and verified. A 40 Vrms/30 Arms class prototype SFCC employing HTS DC reactor was fabricated and short circuit tests that simulate various fault conditions were implemented to verify the control performance of the fault current. Finally, the practical feasibility of application of the SFCC system to the power system was studied. The problems caused by three-phase faults from the power grid were surveyed and transient stability analysis of the power system was conducted by simulations. From the experimental and simulation results, we can verify the feasibility of the SFCC in power system.

  7. Comparison of the quench and fault current limiting characteristics of the flux-coupling type SFCL with single and three-phase transformer

    Science.gov (United States)

    Jung, Byung Ik; Cho, Yong Sun; Park, Hyoung Min; Chung, Dong Chul; Choi, Hyo Sang

    2013-01-01

    The South Korean power grid has a network structure for the flexible operation of the system. The continuously increasing power demand necessitated the increase of power facilities, which decreased the impedance in the power system. As a result, the size of the fault current in the event of a system fault increased. As this increased fault current size is threatening the breaking capacity of the circuit breaker, the main protective device, a solution to this problem is needed. The superconducting fault current limiter (SFCL) has been designed to address this problem. SFCL supports the stable operation of the circuit breaker through its excellent fault-current-limiting operation [1-5]. In this paper, the quench and fault current limiting characteristics of the flux-coupling-type SFCL with one three-phase transformer were compared with those of the same SFCL type but with three single-phase transformers. In the case of the three-phase transformers, both the superconducting elements of the fault and sound phases were quenched, whereas in the case of the single-phase transformer, only that of the fault phase was quenched. For the fault current limiting rate, both cases showed similar rates for the single line-to-ground fault, but for the three-wire earth fault, the fault current limiting rate of the single-phase transformer was over 90% whereas that of the three-phase transformer was about 60%. It appears that when the three-phase transformer was used, the limiting rate decreased because the fluxes by the fault current of each phase were linked in one core. When the power loads of the superconducting elements were compared by fault type, the initial (half-cycle) load was great when the single-phase transformer was applied, whereas for the three-phase transformer, its power load was slightly lower at the initial stage but became greater after the half fault cycle.

  8. TRNFLOW: Integration of the COMIS air current simulation model in the TRNSYS building model TYPE 56; TRNFLOW: Integration des Luftstroemungsmodels COMIS in das TRNSYS Gebaeudemodel TYPE 56

    Energy Technology Data Exchange (ETDEWEB)

    Welfonder, T.; Hiller, M.; Holst, S. [TRANSSOLAR Energietechnik GmbH, Stuttgart (Germany); Weber, A.; Koschenz, M. [EMPA, Abt. Energiesysteme/Haustechnik, Duebendorf (Switzerland)

    2003-07-01

    In the thermal building model TRNSYS Type 56 the air flows between the zones and from the outside are defined by the user as input values. In natural ventilation systems these values depend on external wind pressures and the inside and outside temperatures. To meet these requirements there has to be a link to an airflow model. For these purposes in TRNFLOW the multizone air flow model COMIS has been integrated into Type 56. An internal solver algorithm optimized for this task iterates between the two models in every time step until the results are consistent. The capabilities of the existing user interface PREBID were enlarged to allow input of the necessary data for the air flow model. Therewith a user-friendly handling of the linked models will be guaranteed. With TRNFLOW the building simulation with TRNSYS has moved a major step forward. (orig.)

  9. 78 FR 33768 - Airworthiness Directives; Agusta S.p.A. (Type Certificate Currently Held by AgustaWestland S.p.A...

    Science.gov (United States)

    2013-06-05

    ... Directives; Agusta S.p.A. (Type Certificate Currently Held by AgustaWestland S.p.A.) Helicopters (Agusta...'' address between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. Examining the AD Docket... Operations Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD...

  10. Electrodynamic stabilization conditions for high-temperature superconducting composites with different types of current-voltage characteristic nonlinearity

    Science.gov (United States)

    Arkharov, A. M.; Lavrov, N. A.; Romanovskii, V. R.

    2014-06-01

    The current instability is studied in high-temperature superconducting current-carrying elements with I- V characteristics described by power or exponential equations. Stability analysis of the macroscopic states is carried out in terms of a stationary zero-dimensional model. In linear temperature approximation criteria are derived that allow one to find the maximum allowable values of the induced current, induced electric field intensity, and overheating of the superconductor. A condition is formulated for the complete thermal stabilization of the superconducting composite with regard to the nonlinearity of its I- V characteristic. It is shown that both subcritical and supercritical stable states may arise. In the latter case, the current and electric field intensity are higher than the preset critical parameters of the superconductor. Conditions for these states depending on the properties of the matrix, superconductor's critical current, fill factor, and nonlinearity of the I- V characteristic are discussed. The obtained results considerably augment the class of allowable states for high-temperature superconductors: it is demonstrated that there exist stable resistive conditions from which superconductors cannot pass to the normal state even if the parameters of these conditions are supercritical.

  11. Photothermal resonance

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a method for detecting photo-thermal absorbance of a material utilising a mechanically temperature sensitive resonator (20) and a sample being arrange in thermal communication with the temperature sensitive resonator. The present invention further relates to an ap......The present invention relates to a method for detecting photo-thermal absorbance of a material utilising a mechanically temperature sensitive resonator (20) and a sample being arrange in thermal communication with the temperature sensitive resonator. The present invention further relates...... to an apparatus for detecting photo-thermal absorbance of a sample....

  12. Current Type of Electrical Discharge Machining Pulse Generator%电流型电火花加工脉冲电源的研究

    Institute of Scientific and Technical Information of China (English)

    宋博岩; 赵万生; 邵革良

    2001-01-01

    In this paper, the disadvantages of traditional independent type of electrical discharge machining pulse generator and inverter electrical discharge machining pulse generator are analyzed, and then the principle of current type of electrical discharge machining pulse generator is proposed for the first time. A large quantity of contrast tests between current type of electrical discharge machining pulse generator and traditional independent type of electrical discharge machining pulse generator show that the current type is not only high efficient energy-saving, but also meet the needs of machining performances.%分析了传统独立式电火花加工脉冲电源和逆变式电火花加工脉冲电源的不足,论述了电流型电火花加工脉冲电源的工作原理。大量的样机和独立式脉冲电源的对比工艺试验表明,电流型脉冲电源不仅满足了电火花加工多项性能指标的要求,而且达到了高效节能的效果。

  13. Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor Lamb wave resonator with accurate two-port Y-parameter characterizations.

    Science.gov (United States)

    Wang, Yong; Goh, Wang Ling; Chai, Kevin T-C; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu

    2016-04-01

    The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for Lamb wave resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in Lamb-wave resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of Lamb-wave resonators, providing accurate simulation to Lamb-wave resonators and oscillators.

  14. Phytobioactive compound-based nanodelivery systems for the treatment of type 2 diabetes mellitus – current status

    Science.gov (United States)

    Ganesan, Palanivel; Arulselvan, Palanisamy; Choi, Dong-Kug

    2017-01-01

    Type 2 diabetes mellitus (T2DM) is a major chronic disease that is prevalent worldwide, and it is characterized by an increase in blood glucose, disturbances in the metabolism, and alteration in insulin secretion. Nowadays, food-based therapy has become an important treatment mode for type 2 diabetes, and phytobioactive compounds have gained an increasing amount of attention to this end because they have an effect on multiple biological functions, including the sustained secretion of insulin and regeneration of pancreatic islets cells. However, the poor solubility and lower permeability of these phyto products results in a loss of bioactivity during processing and oral delivery, leading to a significant reduction in the bioavailability of phytobioactive compounds to treat T2DM. Recently, nanotechnological systems have been developed for use as various types of carrier systems to improve the delivery of bioactive compounds and thus obtain a greater bioavailability. Furthermore, carrier systems in most nanodelivery systems are highly biocompatible, with nonimmunologic behavior, a high degree of biodegradability, and greater mucoadhesive strength. Therefore, this review focuses on the various types of nanodelivery systems that can be used for phytobioactive compounds in treating T2DM with greater antidiabetic effects. There is also additional focus on improving the effects of various phytobioactive compounds through nanotechnological delivery to ensure a highly efficient treatment of type 2 diabetes. PMID:28223801

  15. The use of ultrasound to diagnose hepatic steatosis in type 2 diabetes: Intra- and interobserver variability and comparison with magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Williamson, R.M., E-mail: rachel_m_williamson@hotmail.co [Metabolic Unit, Western General Hospital, Edinburgh (United Kingdom); Perry, E.; Glancy, S. [Department of Radiology, Western General Hospital, Edinburgh (United Kingdom); Marshall, I. [Scottish Funding Council Brain Imaging Research Centre, Western General Hospital, Edinburgh (United Kingdom); Gray, C. [Wellcome Trust Clinical Research Facility, Western General Hospital, Edinburgh (United Kingdom); Nee, L.D. [Department of Radiology, Western General Hospital, Edinburgh (United Kingdom); Hayes, P.C. [Department of Hepatology, Royal Infirmary of Edinburgh, Edinburgh (United Kingdom); Forbes, S. [Endocrinology Unit, University of Edinburgh, Queen' s Medical Research Institute, Edinburgh (United Kingdom); Frier, B.M. [Department of Diabetes, Royal Infirmary of Edinburgh, Edinburgh (United Kingdom); Johnston, G.I. [Pfizer Global R and D, Sandwich, Kent (United Kingdom); Lee, A.J. [Centre of Academic Primary Care, University of Aberdeen, Aberdeen (United Kingdom); Reynolds, R.M. [Endocrinology Unit, University of Edinburgh, Queen' s Medical Research Institute, Edinburgh (United Kingdom); Price, J.F. [Centre for Population Health Sciences, University of Edinburgh, Queen' s Medical Research Institute, Edinburgh (United Kingdom); Strachan, M.W.J. [Metabolic Unit, Western General Hospital, Edinburgh (United Kingdom)

    2011-05-15

    Aim: To compare ultrasound gradings of steatosis with fat fraction (FF) on magnetic resonance spectroscopy (MRS; the non-invasive reference standard for quantification of hepatic steatosis), and evaluate inter- and intraobserver variability in the ultrasound gradings. Materials and methods: Triple grading of hepatic ultrasound examination was performed by three independent graders on 131 people with type 2 diabetes. The stored images of 60 of these individuals were assessed twice by each grader on separate occasions. Fifty-eight patients were pre-selected on the basis of ultrasound grading (normal, indeterminate/mild steatosis, or severe steatosis) to undergo {sup 1}H-MRS. The sensitivity and specificity of the ultrasound gradings were determined with reference to MRS data, using two cut-offs of FF to define steatosis, {>=}9% and {>=}6.1%. Results: Median (intraquartile range) MRS FF (%) in the participants graded on ultrasound as normal, indeterminate/mild steatosis, and severe steatosis were 4.2 (1.2-5.7), 4.1 (3.1-8.5) and 19.4 (12.9-27.5), respectively. Using a liver FF of {>=}6.1% on MRS to denote hepatic steatosis, the unadjusted sensitivity and specificity of ultrasound gradings (severe versus other grades of steatosis) were 71 and 100%, respectively. Interobserver agreement within one grade was observed in 79% of cases. Exact intraobserver agreement ranged from 62 to 87%. Conclusion: Hepatic ultrasound provided a good measure of the presence of significant hepatic steatosis with good intra- and interobserver agreement. The grading of a mildly steatotic liver was less secure and, in particular, there was considerable overlap in hepatic FF with those who had a normal liver on ultrasound.

  16. Phytobioactive compound-based nanodelivery systems for the treatment of type 2 diabetes mellitus – current status

    Directory of Open Access Journals (Sweden)

    Ganesan P

    2017-02-01

    Full Text Available Palanivel Ganesan,1,2 Palanisamy Arulselvan,3 Dong-Kug Choi1,2 1Nanotechnology Research Center and Department of Applied Life Science, 2Department of Biotechnology, College of Biomedical and Health Science, Konkuk University, Chungju, Republic of Korea; 3Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, Serdang, Malaysia Abstract: Type 2 diabetes mellitus (T2DM is a major chronic disease that is prevalent worldwide, and it is characterized by an increase in blood glucose, disturbances in the metabolism, and alteration in insulin secretion. Nowadays, food-based therapy has become an important treatment mode for type 2 diabetes, and phytobioactive compounds have gained an increasing amount of attention to this end because they have an effect on multiple biological functions, including the sustained secretion of insulin and regeneration of pancreatic islets cells. However, the poor solubility and lower permeability of these phyto products results in a loss of bioactivity during processing and oral delivery, leading to a significant reduction in the bioavailability of phytobioactive compounds to treat T2DM. Recently, nanotechnological systems have been developed for use as various types of carrier systems to improve the delivery of bioactive compounds and thus obtain a greater bioavailability. Furthermore, carrier systems in most nanodelivery systems are highly biocompatible, with nonimmunologic behavior, a high degree of biodegradability, and greater mucoadhesive strength. Therefore, this review focuses on the various types of nanodelivery systems that can be used for phytobioactive compounds in treating T2DM with greater antidiabetic effects. There is also additional focus on improving the effects of various phytobioactive compounds through nanotechnological delivery to ensure a highly efficient treatment of type 2 diabetes. Keywords: type 2 diabetes, nanodelivery system, phytobioactive compounds

  17. Direct observation of current in type-I edge-localized-mode filaments on the ASDEX upgrade tokamak

    DEFF Research Database (Denmark)

    Vianello, N.; Zuin, M.; Cavazzana, R.;

    2011-01-01

    Magnetically confined plasmas in the high confinement regime are regularly subjected to relaxation oscillations, termed edge localized modes (ELMs), leading to large transport events. Present ELM theories rely on a combined effect of edge current and the edge pressure gradients which result in in...

  18. Critical current and strand stiffness of three types Nb3Sn strand subjected to spatial periodic bending

    NARCIS (Netherlands)

    Nijhuis, Arend; Ilyin, Y.; Wessel, Wilhelm A.J.; Abbas, Wouter

    2006-01-01

    Knowledge of the influence of bending on the critical current (Ic) of Nb3Sn strands is essential for the understanding of the reduction in performance due to transverse electromagnetic load. In particular, for the large cable-in-conduit conductors (CICCs) meant for the international thermonuclear

  19. Fast Resonance Frequency Modulation in Superconducting Stripline Resonator

    OpenAIRE

    Segev, Eran; Abdo, Baleegh; Shtempluck, Oleg; Buks, Eyal

    2006-01-01

    Fast resonance frequency modulation of a superconducting stripline resonator is investigated. The experiments are performed using a novel device which integrates a hot electron detector (HED) into a superconducting stripline ring resonator. Frequency modulation is demonstrated by both applying dc current or voltage to the HED, and by applying optical illumination, with modulation frequencies of up to 4.2GHz. Potential applications for such a device are in telecommunication, quantum cryptograp...

  20. A cross-sectional survey on current status of type 2 diabetes mellitus with overweight or obesity in Guangdong province

    Institute of Scientific and Technical Information of China (English)

    杨帆

    2013-01-01

    Objective To explore the glycemic control statusand related risk factors of overweight or obesity patients with type 2 diabetes mellitus(T2DM) in Guangdong province. Methods The medical records of overweight or obesity patients with T2DM from 60 tertiary and